1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // InstructionCombining - Combine instructions to form fewer, simple
11 // instructions. This pass does not modify the CFG This pass is where algebraic
12 // simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All cmp instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/IntrinsicInst.h"
39 #include "llvm/Pass.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/GlobalVariable.h"
42 #include "llvm/ParameterAttributes.h"
43 #include "llvm/Analysis/ConstantFolding.h"
44 #include "llvm/Target/TargetData.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Support/CallSite.h"
48 #include "llvm/Support/Debug.h"
49 #include "llvm/Support/GetElementPtrTypeIterator.h"
50 #include "llvm/Support/InstVisitor.h"
51 #include "llvm/Support/MathExtras.h"
52 #include "llvm/Support/PatternMatch.h"
53 #include "llvm/Support/Compiler.h"
54 #include "llvm/ADT/DenseMap.h"
55 #include "llvm/ADT/SmallVector.h"
56 #include "llvm/ADT/SmallPtrSet.h"
57 #include "llvm/ADT/Statistic.h"
58 #include "llvm/ADT/STLExtras.h"
62 using namespace llvm::PatternMatch;
64 STATISTIC(NumCombined , "Number of insts combined");
65 STATISTIC(NumConstProp, "Number of constant folds");
66 STATISTIC(NumDeadInst , "Number of dead inst eliminated");
67 STATISTIC(NumDeadStore, "Number of dead stores eliminated");
68 STATISTIC(NumSunkInst , "Number of instructions sunk");
71 class VISIBILITY_HIDDEN InstCombiner
72 : public FunctionPass,
73 public InstVisitor<InstCombiner, Instruction*> {
74 // Worklist of all of the instructions that need to be simplified.
75 std::vector<Instruction*> Worklist;
76 DenseMap<Instruction*, unsigned> WorklistMap;
78 bool MustPreserveLCSSA;
80 static char ID; // Pass identification, replacement for typeid
81 InstCombiner() : FunctionPass((intptr_t)&ID) {}
83 /// AddToWorkList - Add the specified instruction to the worklist if it
84 /// isn't already in it.
85 void AddToWorkList(Instruction *I) {
86 if (WorklistMap.insert(std::make_pair(I, Worklist.size())))
87 Worklist.push_back(I);
90 // RemoveFromWorkList - remove I from the worklist if it exists.
91 void RemoveFromWorkList(Instruction *I) {
92 DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
93 if (It == WorklistMap.end()) return; // Not in worklist.
95 // Don't bother moving everything down, just null out the slot.
96 Worklist[It->second] = 0;
98 WorklistMap.erase(It);
101 Instruction *RemoveOneFromWorkList() {
102 Instruction *I = Worklist.back();
104 WorklistMap.erase(I);
109 /// AddUsersToWorkList - When an instruction is simplified, add all users of
110 /// the instruction to the work lists because they might get more simplified
113 void AddUsersToWorkList(Value &I) {
114 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
116 AddToWorkList(cast<Instruction>(*UI));
119 /// AddUsesToWorkList - When an instruction is simplified, add operands to
120 /// the work lists because they might get more simplified now.
122 void AddUsesToWorkList(Instruction &I) {
123 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
124 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
128 /// AddSoonDeadInstToWorklist - The specified instruction is about to become
129 /// dead. Add all of its operands to the worklist, turning them into
130 /// undef's to reduce the number of uses of those instructions.
132 /// Return the specified operand before it is turned into an undef.
134 Value *AddSoonDeadInstToWorklist(Instruction &I, unsigned op) {
135 Value *R = I.getOperand(op);
137 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
138 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i))) {
140 // Set the operand to undef to drop the use.
141 I.setOperand(i, UndefValue::get(Op->getType()));
148 virtual bool runOnFunction(Function &F);
150 bool DoOneIteration(Function &F, unsigned ItNum);
152 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
153 AU.addRequired<TargetData>();
154 AU.addPreservedID(LCSSAID);
155 AU.setPreservesCFG();
158 TargetData &getTargetData() const { return *TD; }
160 // Visitation implementation - Implement instruction combining for different
161 // instruction types. The semantics are as follows:
163 // null - No change was made
164 // I - Change was made, I is still valid, I may be dead though
165 // otherwise - Change was made, replace I with returned instruction
167 Instruction *visitAdd(BinaryOperator &I);
168 Instruction *visitSub(BinaryOperator &I);
169 Instruction *visitMul(BinaryOperator &I);
170 Instruction *visitURem(BinaryOperator &I);
171 Instruction *visitSRem(BinaryOperator &I);
172 Instruction *visitFRem(BinaryOperator &I);
173 Instruction *commonRemTransforms(BinaryOperator &I);
174 Instruction *commonIRemTransforms(BinaryOperator &I);
175 Instruction *commonDivTransforms(BinaryOperator &I);
176 Instruction *commonIDivTransforms(BinaryOperator &I);
177 Instruction *visitUDiv(BinaryOperator &I);
178 Instruction *visitSDiv(BinaryOperator &I);
179 Instruction *visitFDiv(BinaryOperator &I);
180 Instruction *visitAnd(BinaryOperator &I);
181 Instruction *visitOr (BinaryOperator &I);
182 Instruction *visitXor(BinaryOperator &I);
183 Instruction *visitShl(BinaryOperator &I);
184 Instruction *visitAShr(BinaryOperator &I);
185 Instruction *visitLShr(BinaryOperator &I);
186 Instruction *commonShiftTransforms(BinaryOperator &I);
187 Instruction *visitFCmpInst(FCmpInst &I);
188 Instruction *visitICmpInst(ICmpInst &I);
189 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
190 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
193 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
194 ConstantInt *DivRHS);
196 Instruction *FoldGEPICmp(User *GEPLHS, Value *RHS,
197 ICmpInst::Predicate Cond, Instruction &I);
198 Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
200 Instruction *commonCastTransforms(CastInst &CI);
201 Instruction *commonIntCastTransforms(CastInst &CI);
202 Instruction *commonPointerCastTransforms(CastInst &CI);
203 Instruction *visitTrunc(TruncInst &CI);
204 Instruction *visitZExt(ZExtInst &CI);
205 Instruction *visitSExt(SExtInst &CI);
206 Instruction *visitFPTrunc(CastInst &CI);
207 Instruction *visitFPExt(CastInst &CI);
208 Instruction *visitFPToUI(CastInst &CI);
209 Instruction *visitFPToSI(CastInst &CI);
210 Instruction *visitUIToFP(CastInst &CI);
211 Instruction *visitSIToFP(CastInst &CI);
212 Instruction *visitPtrToInt(CastInst &CI);
213 Instruction *visitIntToPtr(CastInst &CI);
214 Instruction *visitBitCast(BitCastInst &CI);
215 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
217 Instruction *visitSelectInst(SelectInst &CI);
218 Instruction *visitCallInst(CallInst &CI);
219 Instruction *visitInvokeInst(InvokeInst &II);
220 Instruction *visitPHINode(PHINode &PN);
221 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
222 Instruction *visitAllocationInst(AllocationInst &AI);
223 Instruction *visitFreeInst(FreeInst &FI);
224 Instruction *visitLoadInst(LoadInst &LI);
225 Instruction *visitStoreInst(StoreInst &SI);
226 Instruction *visitBranchInst(BranchInst &BI);
227 Instruction *visitSwitchInst(SwitchInst &SI);
228 Instruction *visitInsertElementInst(InsertElementInst &IE);
229 Instruction *visitExtractElementInst(ExtractElementInst &EI);
230 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
232 // visitInstruction - Specify what to return for unhandled instructions...
233 Instruction *visitInstruction(Instruction &I) { return 0; }
236 Instruction *visitCallSite(CallSite CS);
237 bool transformConstExprCastCall(CallSite CS);
238 Instruction *transformCallThroughTrampoline(CallSite CS);
241 // InsertNewInstBefore - insert an instruction New before instruction Old
242 // in the program. Add the new instruction to the worklist.
244 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
245 assert(New && New->getParent() == 0 &&
246 "New instruction already inserted into a basic block!");
247 BasicBlock *BB = Old.getParent();
248 BB->getInstList().insert(&Old, New); // Insert inst
253 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
254 /// This also adds the cast to the worklist. Finally, this returns the
256 Value *InsertCastBefore(Instruction::CastOps opc, Value *V, const Type *Ty,
258 if (V->getType() == Ty) return V;
260 if (Constant *CV = dyn_cast<Constant>(V))
261 return ConstantExpr::getCast(opc, CV, Ty);
263 Instruction *C = CastInst::create(opc, V, Ty, V->getName(), &Pos);
268 // ReplaceInstUsesWith - This method is to be used when an instruction is
269 // found to be dead, replacable with another preexisting expression. Here
270 // we add all uses of I to the worklist, replace all uses of I with the new
271 // value, then return I, so that the inst combiner will know that I was
274 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
275 AddUsersToWorkList(I); // Add all modified instrs to worklist
277 I.replaceAllUsesWith(V);
280 // If we are replacing the instruction with itself, this must be in a
281 // segment of unreachable code, so just clobber the instruction.
282 I.replaceAllUsesWith(UndefValue::get(I.getType()));
287 // UpdateValueUsesWith - This method is to be used when an value is
288 // found to be replacable with another preexisting expression or was
289 // updated. Here we add all uses of I to the worklist, replace all uses of
290 // I with the new value (unless the instruction was just updated), then
291 // return true, so that the inst combiner will know that I was modified.
293 bool UpdateValueUsesWith(Value *Old, Value *New) {
294 AddUsersToWorkList(*Old); // Add all modified instrs to worklist
296 Old->replaceAllUsesWith(New);
297 if (Instruction *I = dyn_cast<Instruction>(Old))
299 if (Instruction *I = dyn_cast<Instruction>(New))
304 // EraseInstFromFunction - When dealing with an instruction that has side
305 // effects or produces a void value, we can't rely on DCE to delete the
306 // instruction. Instead, visit methods should return the value returned by
308 Instruction *EraseInstFromFunction(Instruction &I) {
309 assert(I.use_empty() && "Cannot erase instruction that is used!");
310 AddUsesToWorkList(I);
311 RemoveFromWorkList(&I);
313 return 0; // Don't do anything with FI
317 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
318 /// InsertBefore instruction. This is specialized a bit to avoid inserting
319 /// casts that are known to not do anything...
321 Value *InsertOperandCastBefore(Instruction::CastOps opcode,
322 Value *V, const Type *DestTy,
323 Instruction *InsertBefore);
325 /// SimplifyCommutative - This performs a few simplifications for
326 /// commutative operators.
327 bool SimplifyCommutative(BinaryOperator &I);
329 /// SimplifyCompare - This reorders the operands of a CmpInst to get them in
330 /// most-complex to least-complex order.
331 bool SimplifyCompare(CmpInst &I);
333 /// SimplifyDemandedBits - Attempts to replace V with a simpler value based
334 /// on the demanded bits.
335 bool SimplifyDemandedBits(Value *V, APInt DemandedMask,
336 APInt& KnownZero, APInt& KnownOne,
339 Value *SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts,
340 uint64_t &UndefElts, unsigned Depth = 0);
342 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
343 // PHI node as operand #0, see if we can fold the instruction into the PHI
344 // (which is only possible if all operands to the PHI are constants).
345 Instruction *FoldOpIntoPhi(Instruction &I);
347 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
348 // operator and they all are only used by the PHI, PHI together their
349 // inputs, and do the operation once, to the result of the PHI.
350 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
351 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
354 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
355 ConstantInt *AndRHS, BinaryOperator &TheAnd);
357 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
358 bool isSub, Instruction &I);
359 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
360 bool isSigned, bool Inside, Instruction &IB);
361 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocationInst &AI);
362 Instruction *MatchBSwap(BinaryOperator &I);
363 bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
365 Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
368 char InstCombiner::ID = 0;
369 RegisterPass<InstCombiner> X("instcombine", "Combine redundant instructions");
372 // getComplexity: Assign a complexity or rank value to LLVM Values...
373 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
374 static unsigned getComplexity(Value *V) {
375 if (isa<Instruction>(V)) {
376 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
380 if (isa<Argument>(V)) return 3;
381 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
384 // isOnlyUse - Return true if this instruction will be deleted if we stop using
386 static bool isOnlyUse(Value *V) {
387 return V->hasOneUse() || isa<Constant>(V);
390 // getPromotedType - Return the specified type promoted as it would be to pass
391 // though a va_arg area...
392 static const Type *getPromotedType(const Type *Ty) {
393 if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
394 if (ITy->getBitWidth() < 32)
395 return Type::Int32Ty;
400 /// getBitCastOperand - If the specified operand is a CastInst or a constant
401 /// expression bitcast, return the operand value, otherwise return null.
402 static Value *getBitCastOperand(Value *V) {
403 if (BitCastInst *I = dyn_cast<BitCastInst>(V))
404 return I->getOperand(0);
405 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
406 if (CE->getOpcode() == Instruction::BitCast)
407 return CE->getOperand(0);
411 /// This function is a wrapper around CastInst::isEliminableCastPair. It
412 /// simply extracts arguments and returns what that function returns.
413 static Instruction::CastOps
414 isEliminableCastPair(
415 const CastInst *CI, ///< The first cast instruction
416 unsigned opcode, ///< The opcode of the second cast instruction
417 const Type *DstTy, ///< The target type for the second cast instruction
418 TargetData *TD ///< The target data for pointer size
421 const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
422 const Type *MidTy = CI->getType(); // B from above
424 // Get the opcodes of the two Cast instructions
425 Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
426 Instruction::CastOps secondOp = Instruction::CastOps(opcode);
428 return Instruction::CastOps(
429 CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
430 DstTy, TD->getIntPtrType()));
433 /// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
434 /// in any code being generated. It does not require codegen if V is simple
435 /// enough or if the cast can be folded into other casts.
436 static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V,
437 const Type *Ty, TargetData *TD) {
438 if (V->getType() == Ty || isa<Constant>(V)) return false;
440 // If this is another cast that can be eliminated, it isn't codegen either.
441 if (const CastInst *CI = dyn_cast<CastInst>(V))
442 if (isEliminableCastPair(CI, opcode, Ty, TD))
447 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
448 /// InsertBefore instruction. This is specialized a bit to avoid inserting
449 /// casts that are known to not do anything...
451 Value *InstCombiner::InsertOperandCastBefore(Instruction::CastOps opcode,
452 Value *V, const Type *DestTy,
453 Instruction *InsertBefore) {
454 if (V->getType() == DestTy) return V;
455 if (Constant *C = dyn_cast<Constant>(V))
456 return ConstantExpr::getCast(opcode, C, DestTy);
458 return InsertCastBefore(opcode, V, DestTy, *InsertBefore);
461 // SimplifyCommutative - This performs a few simplifications for commutative
464 // 1. Order operands such that they are listed from right (least complex) to
465 // left (most complex). This puts constants before unary operators before
468 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
469 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
471 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
472 bool Changed = false;
473 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
474 Changed = !I.swapOperands();
476 if (!I.isAssociative()) return Changed;
477 Instruction::BinaryOps Opcode = I.getOpcode();
478 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
479 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
480 if (isa<Constant>(I.getOperand(1))) {
481 Constant *Folded = ConstantExpr::get(I.getOpcode(),
482 cast<Constant>(I.getOperand(1)),
483 cast<Constant>(Op->getOperand(1)));
484 I.setOperand(0, Op->getOperand(0));
485 I.setOperand(1, Folded);
487 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
488 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
489 isOnlyUse(Op) && isOnlyUse(Op1)) {
490 Constant *C1 = cast<Constant>(Op->getOperand(1));
491 Constant *C2 = cast<Constant>(Op1->getOperand(1));
493 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
494 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
495 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
499 I.setOperand(0, New);
500 I.setOperand(1, Folded);
507 /// SimplifyCompare - For a CmpInst this function just orders the operands
508 /// so that theyare listed from right (least complex) to left (most complex).
509 /// This puts constants before unary operators before binary operators.
510 bool InstCombiner::SimplifyCompare(CmpInst &I) {
511 if (getComplexity(I.getOperand(0)) >= getComplexity(I.getOperand(1)))
514 // Compare instructions are not associative so there's nothing else we can do.
518 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
519 // if the LHS is a constant zero (which is the 'negate' form).
521 static inline Value *dyn_castNegVal(Value *V) {
522 if (BinaryOperator::isNeg(V))
523 return BinaryOperator::getNegArgument(V);
525 // Constants can be considered to be negated values if they can be folded.
526 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
527 return ConstantExpr::getNeg(C);
531 static inline Value *dyn_castNotVal(Value *V) {
532 if (BinaryOperator::isNot(V))
533 return BinaryOperator::getNotArgument(V);
535 // Constants can be considered to be not'ed values...
536 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
537 return ConstantInt::get(~C->getValue());
541 // dyn_castFoldableMul - If this value is a multiply that can be folded into
542 // other computations (because it has a constant operand), return the
543 // non-constant operand of the multiply, and set CST to point to the multiplier.
544 // Otherwise, return null.
546 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
547 if (V->hasOneUse() && V->getType()->isInteger())
548 if (Instruction *I = dyn_cast<Instruction>(V)) {
549 if (I->getOpcode() == Instruction::Mul)
550 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
551 return I->getOperand(0);
552 if (I->getOpcode() == Instruction::Shl)
553 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
554 // The multiplier is really 1 << CST.
555 uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
556 uint32_t CSTVal = CST->getLimitedValue(BitWidth);
557 CST = ConstantInt::get(APInt(BitWidth, 1).shl(CSTVal));
558 return I->getOperand(0);
564 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
565 /// expression, return it.
566 static User *dyn_castGetElementPtr(Value *V) {
567 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
568 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
569 if (CE->getOpcode() == Instruction::GetElementPtr)
570 return cast<User>(V);
574 /// AddOne - Add one to a ConstantInt
575 static ConstantInt *AddOne(ConstantInt *C) {
576 APInt Val(C->getValue());
577 return ConstantInt::get(++Val);
579 /// SubOne - Subtract one from a ConstantInt
580 static ConstantInt *SubOne(ConstantInt *C) {
581 APInt Val(C->getValue());
582 return ConstantInt::get(--Val);
584 /// Add - Add two ConstantInts together
585 static ConstantInt *Add(ConstantInt *C1, ConstantInt *C2) {
586 return ConstantInt::get(C1->getValue() + C2->getValue());
588 /// And - Bitwise AND two ConstantInts together
589 static ConstantInt *And(ConstantInt *C1, ConstantInt *C2) {
590 return ConstantInt::get(C1->getValue() & C2->getValue());
592 /// Subtract - Subtract one ConstantInt from another
593 static ConstantInt *Subtract(ConstantInt *C1, ConstantInt *C2) {
594 return ConstantInt::get(C1->getValue() - C2->getValue());
596 /// Multiply - Multiply two ConstantInts together
597 static ConstantInt *Multiply(ConstantInt *C1, ConstantInt *C2) {
598 return ConstantInt::get(C1->getValue() * C2->getValue());
601 /// ComputeMaskedBits - Determine which of the bits specified in Mask are
602 /// known to be either zero or one and return them in the KnownZero/KnownOne
603 /// bit sets. This code only analyzes bits in Mask, in order to short-circuit
605 /// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that
606 /// we cannot optimize based on the assumption that it is zero without changing
607 /// it to be an explicit zero. If we don't change it to zero, other code could
608 /// optimized based on the contradictory assumption that it is non-zero.
609 /// Because instcombine aggressively folds operations with undef args anyway,
610 /// this won't lose us code quality.
611 static void ComputeMaskedBits(Value *V, const APInt &Mask, APInt& KnownZero,
612 APInt& KnownOne, unsigned Depth = 0) {
613 assert(V && "No Value?");
614 assert(Depth <= 6 && "Limit Search Depth");
615 uint32_t BitWidth = Mask.getBitWidth();
616 assert(cast<IntegerType>(V->getType())->getBitWidth() == BitWidth &&
617 KnownZero.getBitWidth() == BitWidth &&
618 KnownOne.getBitWidth() == BitWidth &&
619 "V, Mask, KnownOne and KnownZero should have same BitWidth");
620 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
621 // We know all of the bits for a constant!
622 KnownOne = CI->getValue() & Mask;
623 KnownZero = ~KnownOne & Mask;
627 if (Depth == 6 || Mask == 0)
628 return; // Limit search depth.
630 Instruction *I = dyn_cast<Instruction>(V);
633 KnownZero.clear(); KnownOne.clear(); // Don't know anything.
634 APInt KnownZero2(KnownZero), KnownOne2(KnownOne);
636 switch (I->getOpcode()) {
637 case Instruction::And: {
638 // If either the LHS or the RHS are Zero, the result is zero.
639 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
640 APInt Mask2(Mask & ~KnownZero);
641 ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, Depth+1);
642 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
643 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
645 // Output known-1 bits are only known if set in both the LHS & RHS.
646 KnownOne &= KnownOne2;
647 // Output known-0 are known to be clear if zero in either the LHS | RHS.
648 KnownZero |= KnownZero2;
651 case Instruction::Or: {
652 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
653 APInt Mask2(Mask & ~KnownOne);
654 ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, Depth+1);
655 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
656 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
658 // Output known-0 bits are only known if clear in both the LHS & RHS.
659 KnownZero &= KnownZero2;
660 // Output known-1 are known to be set if set in either the LHS | RHS.
661 KnownOne |= KnownOne2;
664 case Instruction::Xor: {
665 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
666 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
667 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
668 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
670 // Output known-0 bits are known if clear or set in both the LHS & RHS.
671 APInt KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
672 // Output known-1 are known to be set if set in only one of the LHS, RHS.
673 KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
674 KnownZero = KnownZeroOut;
677 case Instruction::Select:
678 ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
679 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
680 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
681 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
683 // Only known if known in both the LHS and RHS.
684 KnownOne &= KnownOne2;
685 KnownZero &= KnownZero2;
687 case Instruction::FPTrunc:
688 case Instruction::FPExt:
689 case Instruction::FPToUI:
690 case Instruction::FPToSI:
691 case Instruction::SIToFP:
692 case Instruction::PtrToInt:
693 case Instruction::UIToFP:
694 case Instruction::IntToPtr:
695 return; // Can't work with floating point or pointers
696 case Instruction::Trunc: {
697 // All these have integer operands
698 uint32_t SrcBitWidth =
699 cast<IntegerType>(I->getOperand(0)->getType())->getBitWidth();
701 MaskIn.zext(SrcBitWidth);
702 KnownZero.zext(SrcBitWidth);
703 KnownOne.zext(SrcBitWidth);
704 ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, Depth+1);
705 KnownZero.trunc(BitWidth);
706 KnownOne.trunc(BitWidth);
709 case Instruction::BitCast: {
710 const Type *SrcTy = I->getOperand(0)->getType();
711 if (SrcTy->isInteger()) {
712 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
717 case Instruction::ZExt: {
718 // Compute the bits in the result that are not present in the input.
719 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
720 uint32_t SrcBitWidth = SrcTy->getBitWidth();
723 MaskIn.trunc(SrcBitWidth);
724 KnownZero.trunc(SrcBitWidth);
725 KnownOne.trunc(SrcBitWidth);
726 ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, Depth+1);
727 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
728 // The top bits are known to be zero.
729 KnownZero.zext(BitWidth);
730 KnownOne.zext(BitWidth);
731 KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
734 case Instruction::SExt: {
735 // Compute the bits in the result that are not present in the input.
736 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
737 uint32_t SrcBitWidth = SrcTy->getBitWidth();
740 MaskIn.trunc(SrcBitWidth);
741 KnownZero.trunc(SrcBitWidth);
742 KnownOne.trunc(SrcBitWidth);
743 ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, Depth+1);
744 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
745 KnownZero.zext(BitWidth);
746 KnownOne.zext(BitWidth);
748 // If the sign bit of the input is known set or clear, then we know the
749 // top bits of the result.
750 if (KnownZero[SrcBitWidth-1]) // Input sign bit known zero
751 KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
752 else if (KnownOne[SrcBitWidth-1]) // Input sign bit known set
753 KnownOne |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
756 case Instruction::Shl:
757 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
758 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
759 uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
760 APInt Mask2(Mask.lshr(ShiftAmt));
761 ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, Depth+1);
762 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
763 KnownZero <<= ShiftAmt;
764 KnownOne <<= ShiftAmt;
765 KnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt); // low bits known 0
769 case Instruction::LShr:
770 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
771 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
772 // Compute the new bits that are at the top now.
773 uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
775 // Unsigned shift right.
776 APInt Mask2(Mask.shl(ShiftAmt));
777 ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero,KnownOne,Depth+1);
778 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
779 KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
780 KnownOne = APIntOps::lshr(KnownOne, ShiftAmt);
781 // high bits known zero.
782 KnownZero |= APInt::getHighBitsSet(BitWidth, ShiftAmt);
786 case Instruction::AShr:
787 // (ashr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
788 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
789 // Compute the new bits that are at the top now.
790 uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
792 // Signed shift right.
793 APInt Mask2(Mask.shl(ShiftAmt));
794 ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero,KnownOne,Depth+1);
795 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
796 KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
797 KnownOne = APIntOps::lshr(KnownOne, ShiftAmt);
799 APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
800 if (KnownZero[BitWidth-ShiftAmt-1]) // New bits are known zero.
801 KnownZero |= HighBits;
802 else if (KnownOne[BitWidth-ShiftAmt-1]) // New bits are known one.
803 KnownOne |= HighBits;
810 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
811 /// this predicate to simplify operations downstream. Mask is known to be zero
812 /// for bits that V cannot have.
813 static bool MaskedValueIsZero(Value *V, const APInt& Mask, unsigned Depth = 0) {
814 APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0);
815 ComputeMaskedBits(V, Mask, KnownZero, KnownOne, Depth);
816 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
817 return (KnownZero & Mask) == Mask;
820 /// ShrinkDemandedConstant - Check to see if the specified operand of the
821 /// specified instruction is a constant integer. If so, check to see if there
822 /// are any bits set in the constant that are not demanded. If so, shrink the
823 /// constant and return true.
824 static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
826 assert(I && "No instruction?");
827 assert(OpNo < I->getNumOperands() && "Operand index too large");
829 // If the operand is not a constant integer, nothing to do.
830 ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
831 if (!OpC) return false;
833 // If there are no bits set that aren't demanded, nothing to do.
834 Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
835 if ((~Demanded & OpC->getValue()) == 0)
838 // This instruction is producing bits that are not demanded. Shrink the RHS.
839 Demanded &= OpC->getValue();
840 I->setOperand(OpNo, ConstantInt::get(Demanded));
844 // ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
845 // set of known zero and one bits, compute the maximum and minimum values that
846 // could have the specified known zero and known one bits, returning them in
848 static void ComputeSignedMinMaxValuesFromKnownBits(const Type *Ty,
849 const APInt& KnownZero,
850 const APInt& KnownOne,
851 APInt& Min, APInt& Max) {
852 uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
853 assert(KnownZero.getBitWidth() == BitWidth &&
854 KnownOne.getBitWidth() == BitWidth &&
855 Min.getBitWidth() == BitWidth && Max.getBitWidth() == BitWidth &&
856 "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
857 APInt UnknownBits = ~(KnownZero|KnownOne);
859 // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
860 // bit if it is unknown.
862 Max = KnownOne|UnknownBits;
864 if (UnknownBits[BitWidth-1]) { // Sign bit is unknown
866 Max.clear(BitWidth-1);
870 // ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
871 // a set of known zero and one bits, compute the maximum and minimum values that
872 // could have the specified known zero and known one bits, returning them in
874 static void ComputeUnsignedMinMaxValuesFromKnownBits(const Type *Ty,
875 const APInt &KnownZero,
876 const APInt &KnownOne,
877 APInt &Min, APInt &Max) {
878 uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth(); BitWidth = BitWidth;
879 assert(KnownZero.getBitWidth() == BitWidth &&
880 KnownOne.getBitWidth() == BitWidth &&
881 Min.getBitWidth() == BitWidth && Max.getBitWidth() &&
882 "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
883 APInt UnknownBits = ~(KnownZero|KnownOne);
885 // The minimum value is when the unknown bits are all zeros.
887 // The maximum value is when the unknown bits are all ones.
888 Max = KnownOne|UnknownBits;
891 /// SimplifyDemandedBits - This function attempts to replace V with a simpler
892 /// value based on the demanded bits. When this function is called, it is known
893 /// that only the bits set in DemandedMask of the result of V are ever used
894 /// downstream. Consequently, depending on the mask and V, it may be possible
895 /// to replace V with a constant or one of its operands. In such cases, this
896 /// function does the replacement and returns true. In all other cases, it
897 /// returns false after analyzing the expression and setting KnownOne and known
898 /// to be one in the expression. KnownZero contains all the bits that are known
899 /// to be zero in the expression. These are provided to potentially allow the
900 /// caller (which might recursively be SimplifyDemandedBits itself) to simplify
901 /// the expression. KnownOne and KnownZero always follow the invariant that
902 /// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that
903 /// the bits in KnownOne and KnownZero may only be accurate for those bits set
904 /// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero
905 /// and KnownOne must all be the same.
906 bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
907 APInt& KnownZero, APInt& KnownOne,
909 assert(V != 0 && "Null pointer of Value???");
910 assert(Depth <= 6 && "Limit Search Depth");
911 uint32_t BitWidth = DemandedMask.getBitWidth();
912 const IntegerType *VTy = cast<IntegerType>(V->getType());
913 assert(VTy->getBitWidth() == BitWidth &&
914 KnownZero.getBitWidth() == BitWidth &&
915 KnownOne.getBitWidth() == BitWidth &&
916 "Value *V, DemandedMask, KnownZero and KnownOne \
917 must have same BitWidth");
918 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
919 // We know all of the bits for a constant!
920 KnownOne = CI->getValue() & DemandedMask;
921 KnownZero = ~KnownOne & DemandedMask;
927 if (!V->hasOneUse()) { // Other users may use these bits.
928 if (Depth != 0) { // Not at the root.
929 // Just compute the KnownZero/KnownOne bits to simplify things downstream.
930 ComputeMaskedBits(V, DemandedMask, KnownZero, KnownOne, Depth);
933 // If this is the root being simplified, allow it to have multiple uses,
934 // just set the DemandedMask to all bits.
935 DemandedMask = APInt::getAllOnesValue(BitWidth);
936 } else if (DemandedMask == 0) { // Not demanding any bits from V.
937 if (V != UndefValue::get(VTy))
938 return UpdateValueUsesWith(V, UndefValue::get(VTy));
940 } else if (Depth == 6) { // Limit search depth.
944 Instruction *I = dyn_cast<Instruction>(V);
945 if (!I) return false; // Only analyze instructions.
947 APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
948 APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne;
949 switch (I->getOpcode()) {
951 case Instruction::And:
952 // If either the LHS or the RHS are Zero, the result is zero.
953 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
954 RHSKnownZero, RHSKnownOne, Depth+1))
956 assert((RHSKnownZero & RHSKnownOne) == 0 &&
957 "Bits known to be one AND zero?");
959 // If something is known zero on the RHS, the bits aren't demanded on the
961 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero,
962 LHSKnownZero, LHSKnownOne, Depth+1))
964 assert((LHSKnownZero & LHSKnownOne) == 0 &&
965 "Bits known to be one AND zero?");
967 // If all of the demanded bits are known 1 on one side, return the other.
968 // These bits cannot contribute to the result of the 'and'.
969 if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
970 (DemandedMask & ~LHSKnownZero))
971 return UpdateValueUsesWith(I, I->getOperand(0));
972 if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
973 (DemandedMask & ~RHSKnownZero))
974 return UpdateValueUsesWith(I, I->getOperand(1));
976 // If all of the demanded bits in the inputs are known zeros, return zero.
977 if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
978 return UpdateValueUsesWith(I, Constant::getNullValue(VTy));
980 // If the RHS is a constant, see if we can simplify it.
981 if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero))
982 return UpdateValueUsesWith(I, I);
984 // Output known-1 bits are only known if set in both the LHS & RHS.
985 RHSKnownOne &= LHSKnownOne;
986 // Output known-0 are known to be clear if zero in either the LHS | RHS.
987 RHSKnownZero |= LHSKnownZero;
989 case Instruction::Or:
990 // If either the LHS or the RHS are One, the result is One.
991 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
992 RHSKnownZero, RHSKnownOne, Depth+1))
994 assert((RHSKnownZero & RHSKnownOne) == 0 &&
995 "Bits known to be one AND zero?");
996 // If something is known one on the RHS, the bits aren't demanded on the
998 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne,
999 LHSKnownZero, LHSKnownOne, Depth+1))
1001 assert((LHSKnownZero & LHSKnownOne) == 0 &&
1002 "Bits known to be one AND zero?");
1004 // If all of the demanded bits are known zero on one side, return the other.
1005 // These bits cannot contribute to the result of the 'or'.
1006 if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
1007 (DemandedMask & ~LHSKnownOne))
1008 return UpdateValueUsesWith(I, I->getOperand(0));
1009 if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
1010 (DemandedMask & ~RHSKnownOne))
1011 return UpdateValueUsesWith(I, I->getOperand(1));
1013 // If all of the potentially set bits on one side are known to be set on
1014 // the other side, just use the 'other' side.
1015 if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
1016 (DemandedMask & (~RHSKnownZero)))
1017 return UpdateValueUsesWith(I, I->getOperand(0));
1018 if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
1019 (DemandedMask & (~LHSKnownZero)))
1020 return UpdateValueUsesWith(I, I->getOperand(1));
1022 // If the RHS is a constant, see if we can simplify it.
1023 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1024 return UpdateValueUsesWith(I, I);
1026 // Output known-0 bits are only known if clear in both the LHS & RHS.
1027 RHSKnownZero &= LHSKnownZero;
1028 // Output known-1 are known to be set if set in either the LHS | RHS.
1029 RHSKnownOne |= LHSKnownOne;
1031 case Instruction::Xor: {
1032 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1033 RHSKnownZero, RHSKnownOne, Depth+1))
1035 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1036 "Bits known to be one AND zero?");
1037 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1038 LHSKnownZero, LHSKnownOne, Depth+1))
1040 assert((LHSKnownZero & LHSKnownOne) == 0 &&
1041 "Bits known to be one AND zero?");
1043 // If all of the demanded bits are known zero on one side, return the other.
1044 // These bits cannot contribute to the result of the 'xor'.
1045 if ((DemandedMask & RHSKnownZero) == DemandedMask)
1046 return UpdateValueUsesWith(I, I->getOperand(0));
1047 if ((DemandedMask & LHSKnownZero) == DemandedMask)
1048 return UpdateValueUsesWith(I, I->getOperand(1));
1050 // Output known-0 bits are known if clear or set in both the LHS & RHS.
1051 APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) |
1052 (RHSKnownOne & LHSKnownOne);
1053 // Output known-1 are known to be set if set in only one of the LHS, RHS.
1054 APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) |
1055 (RHSKnownOne & LHSKnownZero);
1057 // If all of the demanded bits are known to be zero on one side or the
1058 // other, turn this into an *inclusive* or.
1059 // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
1060 if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) {
1062 BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
1064 InsertNewInstBefore(Or, *I);
1065 return UpdateValueUsesWith(I, Or);
1068 // If all of the demanded bits on one side are known, and all of the set
1069 // bits on that side are also known to be set on the other side, turn this
1070 // into an AND, as we know the bits will be cleared.
1071 // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1072 if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) {
1074 if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) {
1075 Constant *AndC = ConstantInt::get(~RHSKnownOne & DemandedMask);
1077 BinaryOperator::createAnd(I->getOperand(0), AndC, "tmp");
1078 InsertNewInstBefore(And, *I);
1079 return UpdateValueUsesWith(I, And);
1083 // If the RHS is a constant, see if we can simplify it.
1084 // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
1085 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1086 return UpdateValueUsesWith(I, I);
1088 RHSKnownZero = KnownZeroOut;
1089 RHSKnownOne = KnownOneOut;
1092 case Instruction::Select:
1093 if (SimplifyDemandedBits(I->getOperand(2), DemandedMask,
1094 RHSKnownZero, RHSKnownOne, Depth+1))
1096 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
1097 LHSKnownZero, LHSKnownOne, Depth+1))
1099 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1100 "Bits known to be one AND zero?");
1101 assert((LHSKnownZero & LHSKnownOne) == 0 &&
1102 "Bits known to be one AND zero?");
1104 // If the operands are constants, see if we can simplify them.
1105 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1106 return UpdateValueUsesWith(I, I);
1107 if (ShrinkDemandedConstant(I, 2, DemandedMask))
1108 return UpdateValueUsesWith(I, I);
1110 // Only known if known in both the LHS and RHS.
1111 RHSKnownOne &= LHSKnownOne;
1112 RHSKnownZero &= LHSKnownZero;
1114 case Instruction::Trunc: {
1116 cast<IntegerType>(I->getOperand(0)->getType())->getBitWidth();
1117 DemandedMask.zext(truncBf);
1118 RHSKnownZero.zext(truncBf);
1119 RHSKnownOne.zext(truncBf);
1120 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1121 RHSKnownZero, RHSKnownOne, Depth+1))
1123 DemandedMask.trunc(BitWidth);
1124 RHSKnownZero.trunc(BitWidth);
1125 RHSKnownOne.trunc(BitWidth);
1126 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1127 "Bits known to be one AND zero?");
1130 case Instruction::BitCast:
1131 if (!I->getOperand(0)->getType()->isInteger())
1134 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1135 RHSKnownZero, RHSKnownOne, Depth+1))
1137 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1138 "Bits known to be one AND zero?");
1140 case Instruction::ZExt: {
1141 // Compute the bits in the result that are not present in the input.
1142 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
1143 uint32_t SrcBitWidth = SrcTy->getBitWidth();
1145 DemandedMask.trunc(SrcBitWidth);
1146 RHSKnownZero.trunc(SrcBitWidth);
1147 RHSKnownOne.trunc(SrcBitWidth);
1148 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
1149 RHSKnownZero, RHSKnownOne, Depth+1))
1151 DemandedMask.zext(BitWidth);
1152 RHSKnownZero.zext(BitWidth);
1153 RHSKnownOne.zext(BitWidth);
1154 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1155 "Bits known to be one AND zero?");
1156 // The top bits are known to be zero.
1157 RHSKnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
1160 case Instruction::SExt: {
1161 // Compute the bits in the result that are not present in the input.
1162 const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
1163 uint32_t SrcBitWidth = SrcTy->getBitWidth();
1165 APInt InputDemandedBits = DemandedMask &
1166 APInt::getLowBitsSet(BitWidth, SrcBitWidth);
1168 APInt NewBits(APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth));
1169 // If any of the sign extended bits are demanded, we know that the sign
1171 if ((NewBits & DemandedMask) != 0)
1172 InputDemandedBits.set(SrcBitWidth-1);
1174 InputDemandedBits.trunc(SrcBitWidth);
1175 RHSKnownZero.trunc(SrcBitWidth);
1176 RHSKnownOne.trunc(SrcBitWidth);
1177 if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits,
1178 RHSKnownZero, RHSKnownOne, Depth+1))
1180 InputDemandedBits.zext(BitWidth);
1181 RHSKnownZero.zext(BitWidth);
1182 RHSKnownOne.zext(BitWidth);
1183 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1184 "Bits known to be one AND zero?");
1186 // If the sign bit of the input is known set or clear, then we know the
1187 // top bits of the result.
1189 // If the input sign bit is known zero, or if the NewBits are not demanded
1190 // convert this into a zero extension.
1191 if (RHSKnownZero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits)
1193 // Convert to ZExt cast
1194 CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName(), I);
1195 return UpdateValueUsesWith(I, NewCast);
1196 } else if (RHSKnownOne[SrcBitWidth-1]) { // Input sign bit known set
1197 RHSKnownOne |= NewBits;
1201 case Instruction::Add: {
1202 // Figure out what the input bits are. If the top bits of the and result
1203 // are not demanded, then the add doesn't demand them from its input
1205 uint32_t NLZ = DemandedMask.countLeadingZeros();
1207 // If there is a constant on the RHS, there are a variety of xformations
1209 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
1210 // If null, this should be simplified elsewhere. Some of the xforms here
1211 // won't work if the RHS is zero.
1215 // If the top bit of the output is demanded, demand everything from the
1216 // input. Otherwise, we demand all the input bits except NLZ top bits.
1217 APInt InDemandedBits(APInt::getLowBitsSet(BitWidth, BitWidth - NLZ));
1219 // Find information about known zero/one bits in the input.
1220 if (SimplifyDemandedBits(I->getOperand(0), InDemandedBits,
1221 LHSKnownZero, LHSKnownOne, Depth+1))
1224 // If the RHS of the add has bits set that can't affect the input, reduce
1226 if (ShrinkDemandedConstant(I, 1, InDemandedBits))
1227 return UpdateValueUsesWith(I, I);
1229 // Avoid excess work.
1230 if (LHSKnownZero == 0 && LHSKnownOne == 0)
1233 // Turn it into OR if input bits are zero.
1234 if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) {
1236 BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
1238 InsertNewInstBefore(Or, *I);
1239 return UpdateValueUsesWith(I, Or);
1242 // We can say something about the output known-zero and known-one bits,
1243 // depending on potential carries from the input constant and the
1244 // unknowns. For example if the LHS is known to have at most the 0x0F0F0
1245 // bits set and the RHS constant is 0x01001, then we know we have a known
1246 // one mask of 0x00001 and a known zero mask of 0xE0F0E.
1248 // To compute this, we first compute the potential carry bits. These are
1249 // the bits which may be modified. I'm not aware of a better way to do
1251 const APInt& RHSVal = RHS->getValue();
1252 APInt CarryBits((~LHSKnownZero + RHSVal) ^ (~LHSKnownZero ^ RHSVal));
1254 // Now that we know which bits have carries, compute the known-1/0 sets.
1256 // Bits are known one if they are known zero in one operand and one in the
1257 // other, and there is no input carry.
1258 RHSKnownOne = ((LHSKnownZero & RHSVal) |
1259 (LHSKnownOne & ~RHSVal)) & ~CarryBits;
1261 // Bits are known zero if they are known zero in both operands and there
1262 // is no input carry.
1263 RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits;
1265 // If the high-bits of this ADD are not demanded, then it does not demand
1266 // the high bits of its LHS or RHS.
1267 if (DemandedMask[BitWidth-1] == 0) {
1268 // Right fill the mask of bits for this ADD to demand the most
1269 // significant bit and all those below it.
1270 APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
1271 if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
1272 LHSKnownZero, LHSKnownOne, Depth+1))
1274 if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
1275 LHSKnownZero, LHSKnownOne, Depth+1))
1281 case Instruction::Sub:
1282 // If the high-bits of this SUB are not demanded, then it does not demand
1283 // the high bits of its LHS or RHS.
1284 if (DemandedMask[BitWidth-1] == 0) {
1285 // Right fill the mask of bits for this SUB to demand the most
1286 // significant bit and all those below it.
1287 uint32_t NLZ = DemandedMask.countLeadingZeros();
1288 APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
1289 if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
1290 LHSKnownZero, LHSKnownOne, Depth+1))
1292 if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
1293 LHSKnownZero, LHSKnownOne, Depth+1))
1297 case Instruction::Shl:
1298 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1299 uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
1300 APInt DemandedMaskIn(DemandedMask.lshr(ShiftAmt));
1301 if (SimplifyDemandedBits(I->getOperand(0), DemandedMaskIn,
1302 RHSKnownZero, RHSKnownOne, Depth+1))
1304 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1305 "Bits known to be one AND zero?");
1306 RHSKnownZero <<= ShiftAmt;
1307 RHSKnownOne <<= ShiftAmt;
1308 // low bits known zero.
1310 RHSKnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt);
1313 case Instruction::LShr:
1314 // For a logical shift right
1315 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1316 uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
1318 // Unsigned shift right.
1319 APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
1320 if (SimplifyDemandedBits(I->getOperand(0), DemandedMaskIn,
1321 RHSKnownZero, RHSKnownOne, Depth+1))
1323 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1324 "Bits known to be one AND zero?");
1325 RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
1326 RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
1328 // Compute the new bits that are at the top now.
1329 APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
1330 RHSKnownZero |= HighBits; // high bits known zero.
1334 case Instruction::AShr:
1335 // If this is an arithmetic shift right and only the low-bit is set, we can
1336 // always convert this into a logical shr, even if the shift amount is
1337 // variable. The low bit of the shift cannot be an input sign bit unless
1338 // the shift amount is >= the size of the datatype, which is undefined.
1339 if (DemandedMask == 1) {
1340 // Perform the logical shift right.
1341 Value *NewVal = BinaryOperator::createLShr(
1342 I->getOperand(0), I->getOperand(1), I->getName());
1343 InsertNewInstBefore(cast<Instruction>(NewVal), *I);
1344 return UpdateValueUsesWith(I, NewVal);
1347 // If the sign bit is the only bit demanded by this ashr, then there is no
1348 // need to do it, the shift doesn't change the high bit.
1349 if (DemandedMask.isSignBit())
1350 return UpdateValueUsesWith(I, I->getOperand(0));
1352 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1353 uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
1355 // Signed shift right.
1356 APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
1357 // If any of the "high bits" are demanded, we should set the sign bit as
1359 if (DemandedMask.countLeadingZeros() <= ShiftAmt)
1360 DemandedMaskIn.set(BitWidth-1);
1361 if (SimplifyDemandedBits(I->getOperand(0),
1363 RHSKnownZero, RHSKnownOne, Depth+1))
1365 assert((RHSKnownZero & RHSKnownOne) == 0 &&
1366 "Bits known to be one AND zero?");
1367 // Compute the new bits that are at the top now.
1368 APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
1369 RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
1370 RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
1372 // Handle the sign bits.
1373 APInt SignBit(APInt::getSignBit(BitWidth));
1374 // Adjust to where it is now in the mask.
1375 SignBit = APIntOps::lshr(SignBit, ShiftAmt);
1377 // If the input sign bit is known to be zero, or if none of the top bits
1378 // are demanded, turn this into an unsigned shift right.
1379 if (RHSKnownZero[BitWidth-ShiftAmt-1] ||
1380 (HighBits & ~DemandedMask) == HighBits) {
1381 // Perform the logical shift right.
1382 Value *NewVal = BinaryOperator::createLShr(
1383 I->getOperand(0), SA, I->getName());
1384 InsertNewInstBefore(cast<Instruction>(NewVal), *I);
1385 return UpdateValueUsesWith(I, NewVal);
1386 } else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one.
1387 RHSKnownOne |= HighBits;
1393 // If the client is only demanding bits that we know, return the known
1395 if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask)
1396 return UpdateValueUsesWith(I, ConstantInt::get(RHSKnownOne));
1401 /// SimplifyDemandedVectorElts - The specified value producecs a vector with
1402 /// 64 or fewer elements. DemandedElts contains the set of elements that are
1403 /// actually used by the caller. This method analyzes which elements of the
1404 /// operand are undef and returns that information in UndefElts.
1406 /// If the information about demanded elements can be used to simplify the
1407 /// operation, the operation is simplified, then the resultant value is
1408 /// returned. This returns null if no change was made.
1409 Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts,
1410 uint64_t &UndefElts,
1412 unsigned VWidth = cast<VectorType>(V->getType())->getNumElements();
1413 assert(VWidth <= 64 && "Vector too wide to analyze!");
1414 uint64_t EltMask = ~0ULL >> (64-VWidth);
1415 assert(DemandedElts != EltMask && (DemandedElts & ~EltMask) == 0 &&
1416 "Invalid DemandedElts!");
1418 if (isa<UndefValue>(V)) {
1419 // If the entire vector is undefined, just return this info.
1420 UndefElts = EltMask;
1422 } else if (DemandedElts == 0) { // If nothing is demanded, provide undef.
1423 UndefElts = EltMask;
1424 return UndefValue::get(V->getType());
1428 if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
1429 const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
1430 Constant *Undef = UndefValue::get(EltTy);
1432 std::vector<Constant*> Elts;
1433 for (unsigned i = 0; i != VWidth; ++i)
1434 if (!(DemandedElts & (1ULL << i))) { // If not demanded, set to undef.
1435 Elts.push_back(Undef);
1436 UndefElts |= (1ULL << i);
1437 } else if (isa<UndefValue>(CP->getOperand(i))) { // Already undef.
1438 Elts.push_back(Undef);
1439 UndefElts |= (1ULL << i);
1440 } else { // Otherwise, defined.
1441 Elts.push_back(CP->getOperand(i));
1444 // If we changed the constant, return it.
1445 Constant *NewCP = ConstantVector::get(Elts);
1446 return NewCP != CP ? NewCP : 0;
1447 } else if (isa<ConstantAggregateZero>(V)) {
1448 // Simplify the CAZ to a ConstantVector where the non-demanded elements are
1450 const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
1451 Constant *Zero = Constant::getNullValue(EltTy);
1452 Constant *Undef = UndefValue::get(EltTy);
1453 std::vector<Constant*> Elts;
1454 for (unsigned i = 0; i != VWidth; ++i)
1455 Elts.push_back((DemandedElts & (1ULL << i)) ? Zero : Undef);
1456 UndefElts = DemandedElts ^ EltMask;
1457 return ConstantVector::get(Elts);
1460 if (!V->hasOneUse()) { // Other users may use these bits.
1461 if (Depth != 0) { // Not at the root.
1462 // TODO: Just compute the UndefElts information recursively.
1466 } else if (Depth == 10) { // Limit search depth.
1470 Instruction *I = dyn_cast<Instruction>(V);
1471 if (!I) return false; // Only analyze instructions.
1473 bool MadeChange = false;
1474 uint64_t UndefElts2;
1476 switch (I->getOpcode()) {
1479 case Instruction::InsertElement: {
1480 // If this is a variable index, we don't know which element it overwrites.
1481 // demand exactly the same input as we produce.
1482 ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2));
1484 // Note that we can't propagate undef elt info, because we don't know
1485 // which elt is getting updated.
1486 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
1487 UndefElts2, Depth+1);
1488 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
1492 // If this is inserting an element that isn't demanded, remove this
1494 unsigned IdxNo = Idx->getZExtValue();
1495 if (IdxNo >= VWidth || (DemandedElts & (1ULL << IdxNo)) == 0)
1496 return AddSoonDeadInstToWorklist(*I, 0);
1498 // Otherwise, the element inserted overwrites whatever was there, so the
1499 // input demanded set is simpler than the output set.
1500 TmpV = SimplifyDemandedVectorElts(I->getOperand(0),
1501 DemandedElts & ~(1ULL << IdxNo),
1502 UndefElts, Depth+1);
1503 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
1505 // The inserted element is defined.
1506 UndefElts |= 1ULL << IdxNo;
1509 case Instruction::BitCast: {
1510 // Vector->vector casts only.
1511 const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType());
1513 unsigned InVWidth = VTy->getNumElements();
1514 uint64_t InputDemandedElts = 0;
1517 if (VWidth == InVWidth) {
1518 // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
1519 // elements as are demanded of us.
1521 InputDemandedElts = DemandedElts;
1522 } else if (VWidth > InVWidth) {
1526 // If there are more elements in the result than there are in the source,
1527 // then an input element is live if any of the corresponding output
1528 // elements are live.
1529 Ratio = VWidth/InVWidth;
1530 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
1531 if (DemandedElts & (1ULL << OutIdx))
1532 InputDemandedElts |= 1ULL << (OutIdx/Ratio);
1538 // If there are more elements in the source than there are in the result,
1539 // then an input element is live if the corresponding output element is
1541 Ratio = InVWidth/VWidth;
1542 for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
1543 if (DemandedElts & (1ULL << InIdx/Ratio))
1544 InputDemandedElts |= 1ULL << InIdx;
1547 // div/rem demand all inputs, because they don't want divide by zero.
1548 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), InputDemandedElts,
1549 UndefElts2, Depth+1);
1551 I->setOperand(0, TmpV);
1555 UndefElts = UndefElts2;
1556 if (VWidth > InVWidth) {
1557 assert(0 && "Unimp");
1558 // If there are more elements in the result than there are in the source,
1559 // then an output element is undef if the corresponding input element is
1561 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
1562 if (UndefElts2 & (1ULL << (OutIdx/Ratio)))
1563 UndefElts |= 1ULL << OutIdx;
1564 } else if (VWidth < InVWidth) {
1565 assert(0 && "Unimp");
1566 // If there are more elements in the source than there are in the result,
1567 // then a result element is undef if all of the corresponding input
1568 // elements are undef.
1569 UndefElts = ~0ULL >> (64-VWidth); // Start out all undef.
1570 for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
1571 if ((UndefElts2 & (1ULL << InIdx)) == 0) // Not undef?
1572 UndefElts &= ~(1ULL << (InIdx/Ratio)); // Clear undef bit.
1576 case Instruction::And:
1577 case Instruction::Or:
1578 case Instruction::Xor:
1579 case Instruction::Add:
1580 case Instruction::Sub:
1581 case Instruction::Mul:
1582 // div/rem demand all inputs, because they don't want divide by zero.
1583 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
1584 UndefElts, Depth+1);
1585 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
1586 TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts,
1587 UndefElts2, Depth+1);
1588 if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
1590 // Output elements are undefined if both are undefined. Consider things
1591 // like undef&0. The result is known zero, not undef.
1592 UndefElts &= UndefElts2;
1595 case Instruction::Call: {
1596 IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
1598 switch (II->getIntrinsicID()) {
1601 // Binary vector operations that work column-wise. A dest element is a
1602 // function of the corresponding input elements from the two inputs.
1603 case Intrinsic::x86_sse_sub_ss:
1604 case Intrinsic::x86_sse_mul_ss:
1605 case Intrinsic::x86_sse_min_ss:
1606 case Intrinsic::x86_sse_max_ss:
1607 case Intrinsic::x86_sse2_sub_sd:
1608 case Intrinsic::x86_sse2_mul_sd:
1609 case Intrinsic::x86_sse2_min_sd:
1610 case Intrinsic::x86_sse2_max_sd:
1611 TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
1612 UndefElts, Depth+1);
1613 if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; }
1614 TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts,
1615 UndefElts2, Depth+1);
1616 if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; }
1618 // If only the low elt is demanded and this is a scalarizable intrinsic,
1619 // scalarize it now.
1620 if (DemandedElts == 1) {
1621 switch (II->getIntrinsicID()) {
1623 case Intrinsic::x86_sse_sub_ss:
1624 case Intrinsic::x86_sse_mul_ss:
1625 case Intrinsic::x86_sse2_sub_sd:
1626 case Intrinsic::x86_sse2_mul_sd:
1627 // TODO: Lower MIN/MAX/ABS/etc
1628 Value *LHS = II->getOperand(1);
1629 Value *RHS = II->getOperand(2);
1630 // Extract the element as scalars.
1631 LHS = InsertNewInstBefore(new ExtractElementInst(LHS, 0U,"tmp"), *II);
1632 RHS = InsertNewInstBefore(new ExtractElementInst(RHS, 0U,"tmp"), *II);
1634 switch (II->getIntrinsicID()) {
1635 default: assert(0 && "Case stmts out of sync!");
1636 case Intrinsic::x86_sse_sub_ss:
1637 case Intrinsic::x86_sse2_sub_sd:
1638 TmpV = InsertNewInstBefore(BinaryOperator::createSub(LHS, RHS,
1639 II->getName()), *II);
1641 case Intrinsic::x86_sse_mul_ss:
1642 case Intrinsic::x86_sse2_mul_sd:
1643 TmpV = InsertNewInstBefore(BinaryOperator::createMul(LHS, RHS,
1644 II->getName()), *II);
1649 new InsertElementInst(UndefValue::get(II->getType()), TmpV, 0U,
1651 InsertNewInstBefore(New, *II);
1652 AddSoonDeadInstToWorklist(*II, 0);
1657 // Output elements are undefined if both are undefined. Consider things
1658 // like undef&0. The result is known zero, not undef.
1659 UndefElts &= UndefElts2;
1665 return MadeChange ? I : 0;
1668 /// @returns true if the specified compare predicate is
1669 /// true when both operands are equal...
1670 /// @brief Determine if the icmp Predicate is true when both operands are equal
1671 static bool isTrueWhenEqual(ICmpInst::Predicate pred) {
1672 return pred == ICmpInst::ICMP_EQ || pred == ICmpInst::ICMP_UGE ||
1673 pred == ICmpInst::ICMP_SGE || pred == ICmpInst::ICMP_ULE ||
1674 pred == ICmpInst::ICMP_SLE;
1677 /// @returns true if the specified compare instruction is
1678 /// true when both operands are equal...
1679 /// @brief Determine if the ICmpInst returns true when both operands are equal
1680 static bool isTrueWhenEqual(ICmpInst &ICI) {
1681 return isTrueWhenEqual(ICI.getPredicate());
1684 /// AssociativeOpt - Perform an optimization on an associative operator. This
1685 /// function is designed to check a chain of associative operators for a
1686 /// potential to apply a certain optimization. Since the optimization may be
1687 /// applicable if the expression was reassociated, this checks the chain, then
1688 /// reassociates the expression as necessary to expose the optimization
1689 /// opportunity. This makes use of a special Functor, which must define
1690 /// 'shouldApply' and 'apply' methods.
1692 template<typename Functor>
1693 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
1694 unsigned Opcode = Root.getOpcode();
1695 Value *LHS = Root.getOperand(0);
1697 // Quick check, see if the immediate LHS matches...
1698 if (F.shouldApply(LHS))
1699 return F.apply(Root);
1701 // Otherwise, if the LHS is not of the same opcode as the root, return.
1702 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1703 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
1704 // Should we apply this transform to the RHS?
1705 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
1707 // If not to the RHS, check to see if we should apply to the LHS...
1708 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
1709 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
1713 // If the functor wants to apply the optimization to the RHS of LHSI,
1714 // reassociate the expression from ((? op A) op B) to (? op (A op B))
1716 BasicBlock *BB = Root.getParent();
1718 // Now all of the instructions are in the current basic block, go ahead
1719 // and perform the reassociation.
1720 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
1722 // First move the selected RHS to the LHS of the root...
1723 Root.setOperand(0, LHSI->getOperand(1));
1725 // Make what used to be the LHS of the root be the user of the root...
1726 Value *ExtraOperand = TmpLHSI->getOperand(1);
1727 if (&Root == TmpLHSI) {
1728 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
1731 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
1732 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
1733 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
1734 BasicBlock::iterator ARI = &Root; ++ARI;
1735 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
1738 // Now propagate the ExtraOperand down the chain of instructions until we
1740 while (TmpLHSI != LHSI) {
1741 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
1742 // Move the instruction to immediately before the chain we are
1743 // constructing to avoid breaking dominance properties.
1744 NextLHSI->getParent()->getInstList().remove(NextLHSI);
1745 BB->getInstList().insert(ARI, NextLHSI);
1748 Value *NextOp = NextLHSI->getOperand(1);
1749 NextLHSI->setOperand(1, ExtraOperand);
1751 ExtraOperand = NextOp;
1754 // Now that the instructions are reassociated, have the functor perform
1755 // the transformation...
1756 return F.apply(Root);
1759 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
1765 // AddRHS - Implements: X + X --> X << 1
1768 AddRHS(Value *rhs) : RHS(rhs) {}
1769 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1770 Instruction *apply(BinaryOperator &Add) const {
1771 return BinaryOperator::createShl(Add.getOperand(0),
1772 ConstantInt::get(Add.getType(), 1));
1776 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
1778 struct AddMaskingAnd {
1780 AddMaskingAnd(Constant *c) : C2(c) {}
1781 bool shouldApply(Value *LHS) const {
1783 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
1784 ConstantExpr::getAnd(C1, C2)->isNullValue();
1786 Instruction *apply(BinaryOperator &Add) const {
1787 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
1791 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
1793 if (CastInst *CI = dyn_cast<CastInst>(&I)) {
1794 if (Constant *SOC = dyn_cast<Constant>(SO))
1795 return ConstantExpr::getCast(CI->getOpcode(), SOC, I.getType());
1797 return IC->InsertNewInstBefore(CastInst::create(
1798 CI->getOpcode(), SO, I.getType(), SO->getName() + ".cast"), I);
1801 // Figure out if the constant is the left or the right argument.
1802 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
1803 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
1805 if (Constant *SOC = dyn_cast<Constant>(SO)) {
1807 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
1808 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
1811 Value *Op0 = SO, *Op1 = ConstOperand;
1813 std::swap(Op0, Op1);
1815 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
1816 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
1817 else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
1818 New = CmpInst::create(CI->getOpcode(), CI->getPredicate(), Op0, Op1,
1819 SO->getName()+".cmp");
1821 assert(0 && "Unknown binary instruction type!");
1824 return IC->InsertNewInstBefore(New, I);
1827 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
1828 // constant as the other operand, try to fold the binary operator into the
1829 // select arguments. This also works for Cast instructions, which obviously do
1830 // not have a second operand.
1831 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
1833 // Don't modify shared select instructions
1834 if (!SI->hasOneUse()) return 0;
1835 Value *TV = SI->getOperand(1);
1836 Value *FV = SI->getOperand(2);
1838 if (isa<Constant>(TV) || isa<Constant>(FV)) {
1839 // Bool selects with constant operands can be folded to logical ops.
1840 if (SI->getType() == Type::Int1Ty) return 0;
1842 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
1843 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
1845 return new SelectInst(SI->getCondition(), SelectTrueVal,
1852 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
1853 /// node as operand #0, see if we can fold the instruction into the PHI (which
1854 /// is only possible if all operands to the PHI are constants).
1855 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
1856 PHINode *PN = cast<PHINode>(I.getOperand(0));
1857 unsigned NumPHIValues = PN->getNumIncomingValues();
1858 if (!PN->hasOneUse() || NumPHIValues == 0) return 0;
1860 // Check to see if all of the operands of the PHI are constants. If there is
1861 // one non-constant value, remember the BB it is. If there is more than one
1862 // or if *it* is a PHI, bail out.
1863 BasicBlock *NonConstBB = 0;
1864 for (unsigned i = 0; i != NumPHIValues; ++i)
1865 if (!isa<Constant>(PN->getIncomingValue(i))) {
1866 if (NonConstBB) return 0; // More than one non-const value.
1867 if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi.
1868 NonConstBB = PN->getIncomingBlock(i);
1870 // If the incoming non-constant value is in I's block, we have an infinite
1872 if (NonConstBB == I.getParent())
1876 // If there is exactly one non-constant value, we can insert a copy of the
1877 // operation in that block. However, if this is a critical edge, we would be
1878 // inserting the computation one some other paths (e.g. inside a loop). Only
1879 // do this if the pred block is unconditionally branching into the phi block.
1881 BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
1882 if (!BI || !BI->isUnconditional()) return 0;
1885 // Okay, we can do the transformation: create the new PHI node.
1886 PHINode *NewPN = new PHINode(I.getType(), "");
1887 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
1888 InsertNewInstBefore(NewPN, *PN);
1889 NewPN->takeName(PN);
1891 // Next, add all of the operands to the PHI.
1892 if (I.getNumOperands() == 2) {
1893 Constant *C = cast<Constant>(I.getOperand(1));
1894 for (unsigned i = 0; i != NumPHIValues; ++i) {
1896 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
1897 if (CmpInst *CI = dyn_cast<CmpInst>(&I))
1898 InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
1900 InV = ConstantExpr::get(I.getOpcode(), InC, C);
1902 assert(PN->getIncomingBlock(i) == NonConstBB);
1903 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
1904 InV = BinaryOperator::create(BO->getOpcode(),
1905 PN->getIncomingValue(i), C, "phitmp",
1906 NonConstBB->getTerminator());
1907 else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
1908 InV = CmpInst::create(CI->getOpcode(),
1910 PN->getIncomingValue(i), C, "phitmp",
1911 NonConstBB->getTerminator());
1913 assert(0 && "Unknown binop!");
1915 AddToWorkList(cast<Instruction>(InV));
1917 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
1920 CastInst *CI = cast<CastInst>(&I);
1921 const Type *RetTy = CI->getType();
1922 for (unsigned i = 0; i != NumPHIValues; ++i) {
1924 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
1925 InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
1927 assert(PN->getIncomingBlock(i) == NonConstBB);
1928 InV = CastInst::create(CI->getOpcode(), PN->getIncomingValue(i),
1929 I.getType(), "phitmp",
1930 NonConstBB->getTerminator());
1931 AddToWorkList(cast<Instruction>(InV));
1933 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
1936 return ReplaceInstUsesWith(I, NewPN);
1939 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
1940 bool Changed = SimplifyCommutative(I);
1941 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1943 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1944 // X + undef -> undef
1945 if (isa<UndefValue>(RHS))
1946 return ReplaceInstUsesWith(I, RHS);
1949 if (!I.getType()->isFPOrFPVector()) { // NOTE: -0 + +0 = +0.
1950 if (RHSC->isNullValue())
1951 return ReplaceInstUsesWith(I, LHS);
1952 } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1953 if (CFP->isExactlyValue(ConstantFP::getNegativeZero
1954 (I.getType())->getValueAPF()))
1955 return ReplaceInstUsesWith(I, LHS);
1958 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
1959 // X + (signbit) --> X ^ signbit
1960 const APInt& Val = CI->getValue();
1961 uint32_t BitWidth = Val.getBitWidth();
1962 if (Val == APInt::getSignBit(BitWidth))
1963 return BinaryOperator::createXor(LHS, RHS);
1965 // See if SimplifyDemandedBits can simplify this. This handles stuff like
1966 // (X & 254)+1 -> (X&254)|1
1967 if (!isa<VectorType>(I.getType())) {
1968 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
1969 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
1970 KnownZero, KnownOne))
1975 if (isa<PHINode>(LHS))
1976 if (Instruction *NV = FoldOpIntoPhi(I))
1979 ConstantInt *XorRHS = 0;
1981 if (isa<ConstantInt>(RHSC) &&
1982 match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
1983 uint32_t TySizeBits = I.getType()->getPrimitiveSizeInBits();
1984 const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
1986 uint32_t Size = TySizeBits / 2;
1987 APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
1988 APInt CFF80Val(-C0080Val);
1990 if (TySizeBits > Size) {
1991 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
1992 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
1993 if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
1994 (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
1995 // This is a sign extend if the top bits are known zero.
1996 if (!MaskedValueIsZero(XorLHS,
1997 APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
1998 Size = 0; // Not a sign ext, but can't be any others either.
2003 C0080Val = APIntOps::lshr(C0080Val, Size);
2004 CFF80Val = APIntOps::ashr(CFF80Val, Size);
2005 } while (Size >= 1);
2007 // FIXME: This shouldn't be necessary. When the backends can handle types
2008 // with funny bit widths then this whole cascade of if statements should
2009 // be removed. It is just here to get the size of the "middle" type back
2010 // up to something that the back ends can handle.
2011 const Type *MiddleType = 0;
2014 case 32: MiddleType = Type::Int32Ty; break;
2015 case 16: MiddleType = Type::Int16Ty; break;
2016 case 8: MiddleType = Type::Int8Ty; break;
2019 Instruction *NewTrunc = new TruncInst(XorLHS, MiddleType, "sext");
2020 InsertNewInstBefore(NewTrunc, I);
2021 return new SExtInst(NewTrunc, I.getType(), I.getName());
2027 if (I.getType()->isInteger() && I.getType() != Type::Int1Ty) {
2028 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
2030 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
2031 if (RHSI->getOpcode() == Instruction::Sub)
2032 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
2033 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
2035 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
2036 if (LHSI->getOpcode() == Instruction::Sub)
2037 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
2038 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
2043 if (Value *V = dyn_castNegVal(LHS))
2044 return BinaryOperator::createSub(RHS, V);
2047 if (!isa<Constant>(RHS))
2048 if (Value *V = dyn_castNegVal(RHS))
2049 return BinaryOperator::createSub(LHS, V);
2053 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
2054 if (X == RHS) // X*C + X --> X * (C+1)
2055 return BinaryOperator::createMul(RHS, AddOne(C2));
2057 // X*C1 + X*C2 --> X * (C1+C2)
2059 if (X == dyn_castFoldableMul(RHS, C1))
2060 return BinaryOperator::createMul(X, Add(C1, C2));
2063 // X + X*C --> X * (C+1)
2064 if (dyn_castFoldableMul(RHS, C2) == LHS)
2065 return BinaryOperator::createMul(LHS, AddOne(C2));
2067 // X + ~X --> -1 since ~X = -X-1
2068 if (dyn_castNotVal(LHS) == RHS || dyn_castNotVal(RHS) == LHS)
2069 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
2072 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
2073 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
2074 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
2077 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
2079 if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
2080 return BinaryOperator::createSub(SubOne(CRHS), X);
2082 // (X & FF00) + xx00 -> (X+xx00) & FF00
2083 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
2084 Constant *Anded = And(CRHS, C2);
2085 if (Anded == CRHS) {
2086 // See if all bits from the first bit set in the Add RHS up are included
2087 // in the mask. First, get the rightmost bit.
2088 const APInt& AddRHSV = CRHS->getValue();
2090 // Form a mask of all bits from the lowest bit added through the top.
2091 APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
2093 // See if the and mask includes all of these bits.
2094 APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
2096 if (AddRHSHighBits == AddRHSHighBitsAnd) {
2097 // Okay, the xform is safe. Insert the new add pronto.
2098 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
2099 LHS->getName()), I);
2100 return BinaryOperator::createAnd(NewAdd, C2);
2105 // Try to fold constant add into select arguments.
2106 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
2107 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2111 // add (cast *A to intptrtype) B ->
2112 // cast (GEP (cast *A to sbyte*) B) ->
2115 CastInst *CI = dyn_cast<CastInst>(LHS);
2118 CI = dyn_cast<CastInst>(RHS);
2121 if (CI && CI->getType()->isSized() &&
2122 (CI->getType()->getPrimitiveSizeInBits() ==
2123 TD->getIntPtrType()->getPrimitiveSizeInBits())
2124 && isa<PointerType>(CI->getOperand(0)->getType())) {
2126 cast<PointerType>(CI->getOperand(0)->getType())->getAddressSpace();
2127 Value *I2 = InsertCastBefore(Instruction::BitCast, CI->getOperand(0),
2128 PointerType::get(Type::Int8Ty, AS), I);
2129 I2 = InsertNewInstBefore(new GetElementPtrInst(I2, Other, "ctg2"), I);
2130 return new PtrToIntInst(I2, CI->getType());
2134 // add (select X 0 (sub n A)) A ->
2137 SelectInst *SI = dyn_cast<SelectInst>(LHS);
2140 SI = dyn_cast<SelectInst>(RHS);
2144 Value *TV = SI->getTrueValue();
2145 Value *FV = SI->getFalseValue();
2148 // Can we fold the add into the argument of the select?
2149 // We check both true and false select arguments for a matching subtract.
2150 ConstantInt *C1, *C2;
2151 if (match(FV, m_ConstantInt(C1)) && C1->getValue() == 0 &&
2152 match(TV, m_Sub(m_ConstantInt(C2), m_Value(A))) &&
2154 // We managed to fold the add into the true select value.
2155 return new SelectInst(SI->getCondition(), C2, A);
2156 } else if (match(TV, m_ConstantInt(C1)) && C1->getValue() == 0 &&
2157 match(FV, m_Sub(m_ConstantInt(C2), m_Value(A))) &&
2159 // We managed to fold the add into the false select value.
2160 return new SelectInst(SI->getCondition(), A, C2);
2165 return Changed ? &I : 0;
2168 // isSignBit - Return true if the value represented by the constant only has the
2169 // highest order bit set.
2170 static bool isSignBit(ConstantInt *CI) {
2171 uint32_t NumBits = CI->getType()->getPrimitiveSizeInBits();
2172 return CI->getValue() == APInt::getSignBit(NumBits);
2175 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
2176 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2178 if (Op0 == Op1) // sub X, X -> 0
2179 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2181 // If this is a 'B = x-(-A)', change to B = x+A...
2182 if (Value *V = dyn_castNegVal(Op1))
2183 return BinaryOperator::createAdd(Op0, V);
2185 if (isa<UndefValue>(Op0))
2186 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
2187 if (isa<UndefValue>(Op1))
2188 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
2190 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
2191 // Replace (-1 - A) with (~A)...
2192 if (C->isAllOnesValue())
2193 return BinaryOperator::createNot(Op1);
2195 // C - ~X == X + (1+C)
2197 if (match(Op1, m_Not(m_Value(X))))
2198 return BinaryOperator::createAdd(X, AddOne(C));
2200 // -(X >>u 31) -> (X >>s 31)
2201 // -(X >>s 31) -> (X >>u 31)
2203 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1))
2204 if (SI->getOpcode() == Instruction::LShr) {
2205 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
2206 // Check to see if we are shifting out everything but the sign bit.
2207 if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
2208 SI->getType()->getPrimitiveSizeInBits()-1) {
2209 // Ok, the transformation is safe. Insert AShr.
2210 return BinaryOperator::create(Instruction::AShr,
2211 SI->getOperand(0), CU, SI->getName());
2215 else if (SI->getOpcode() == Instruction::AShr) {
2216 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
2217 // Check to see if we are shifting out everything but the sign bit.
2218 if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
2219 SI->getType()->getPrimitiveSizeInBits()-1) {
2220 // Ok, the transformation is safe. Insert LShr.
2221 return BinaryOperator::createLShr(
2222 SI->getOperand(0), CU, SI->getName());
2228 // Try to fold constant sub into select arguments.
2229 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
2230 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2233 if (isa<PHINode>(Op0))
2234 if (Instruction *NV = FoldOpIntoPhi(I))
2238 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
2239 if (Op1I->getOpcode() == Instruction::Add &&
2240 !Op0->getType()->isFPOrFPVector()) {
2241 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
2242 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
2243 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
2244 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
2245 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
2246 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
2247 // C1-(X+C2) --> (C1-C2)-X
2248 return BinaryOperator::createSub(Subtract(CI1, CI2),
2249 Op1I->getOperand(0));
2253 if (Op1I->hasOneUse()) {
2254 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
2255 // is not used by anyone else...
2257 if (Op1I->getOpcode() == Instruction::Sub &&
2258 !Op1I->getType()->isFPOrFPVector()) {
2259 // Swap the two operands of the subexpr...
2260 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
2261 Op1I->setOperand(0, IIOp1);
2262 Op1I->setOperand(1, IIOp0);
2264 // Create the new top level add instruction...
2265 return BinaryOperator::createAdd(Op0, Op1);
2268 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
2270 if (Op1I->getOpcode() == Instruction::And &&
2271 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
2272 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
2275 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
2276 return BinaryOperator::createAnd(Op0, NewNot);
2279 // 0 - (X sdiv C) -> (X sdiv -C)
2280 if (Op1I->getOpcode() == Instruction::SDiv)
2281 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
2283 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
2284 return BinaryOperator::createSDiv(Op1I->getOperand(0),
2285 ConstantExpr::getNeg(DivRHS));
2287 // X - X*C --> X * (1-C)
2288 ConstantInt *C2 = 0;
2289 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
2290 Constant *CP1 = Subtract(ConstantInt::get(I.getType(), 1), C2);
2291 return BinaryOperator::createMul(Op0, CP1);
2294 // X - ((X / Y) * Y) --> X % Y
2295 if (Op1I->getOpcode() == Instruction::Mul)
2296 if (Instruction *I = dyn_cast<Instruction>(Op1I->getOperand(0)))
2297 if (Op0 == I->getOperand(0) &&
2298 Op1I->getOperand(1) == I->getOperand(1)) {
2299 if (I->getOpcode() == Instruction::SDiv)
2300 return BinaryOperator::createSRem(Op0, Op1I->getOperand(1));
2301 if (I->getOpcode() == Instruction::UDiv)
2302 return BinaryOperator::createURem(Op0, Op1I->getOperand(1));
2307 if (!Op0->getType()->isFPOrFPVector())
2308 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
2309 if (Op0I->getOpcode() == Instruction::Add) {
2310 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
2311 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2312 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
2313 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2314 } else if (Op0I->getOpcode() == Instruction::Sub) {
2315 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
2316 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
2320 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
2321 if (X == Op1) // X*C - X --> X * (C-1)
2322 return BinaryOperator::createMul(Op1, SubOne(C1));
2324 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
2325 if (X == dyn_castFoldableMul(Op1, C2))
2326 return BinaryOperator::createMul(Op1, Subtract(C1, C2));
2331 /// isSignBitCheck - Given an exploded icmp instruction, return true if the
2332 /// comparison only checks the sign bit. If it only checks the sign bit, set
2333 /// TrueIfSigned if the result of the comparison is true when the input value is
2335 static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
2336 bool &TrueIfSigned) {
2338 case ICmpInst::ICMP_SLT: // True if LHS s< 0
2339 TrueIfSigned = true;
2340 return RHS->isZero();
2341 case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
2342 TrueIfSigned = true;
2343 return RHS->isAllOnesValue();
2344 case ICmpInst::ICMP_SGT: // True if LHS s> -1
2345 TrueIfSigned = false;
2346 return RHS->isAllOnesValue();
2347 case ICmpInst::ICMP_UGT:
2348 // True if LHS u> RHS and RHS == high-bit-mask - 1
2349 TrueIfSigned = true;
2350 return RHS->getValue() ==
2351 APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
2352 case ICmpInst::ICMP_UGE:
2353 // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
2354 TrueIfSigned = true;
2355 return RHS->getValue() ==
2356 APInt::getSignBit(RHS->getType()->getPrimitiveSizeInBits());
2362 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
2363 bool Changed = SimplifyCommutative(I);
2364 Value *Op0 = I.getOperand(0);
2366 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
2367 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2369 // Simplify mul instructions with a constant RHS...
2370 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
2371 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2373 // ((X << C1)*C2) == (X * (C2 << C1))
2374 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
2375 if (SI->getOpcode() == Instruction::Shl)
2376 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
2377 return BinaryOperator::createMul(SI->getOperand(0),
2378 ConstantExpr::getShl(CI, ShOp));
2381 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
2382 if (CI->equalsInt(1)) // X * 1 == X
2383 return ReplaceInstUsesWith(I, Op0);
2384 if (CI->isAllOnesValue()) // X * -1 == 0 - X
2385 return BinaryOperator::createNeg(Op0, I.getName());
2387 const APInt& Val = cast<ConstantInt>(CI)->getValue();
2388 if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
2389 return BinaryOperator::createShl(Op0,
2390 ConstantInt::get(Op0->getType(), Val.logBase2()));
2392 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
2393 if (Op1F->isNullValue())
2394 return ReplaceInstUsesWith(I, Op1);
2396 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
2397 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
2398 // We need a better interface for long double here.
2399 if (Op1->getType() == Type::FloatTy || Op1->getType() == Type::DoubleTy)
2400 if (Op1F->isExactlyValue(1.0))
2401 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
2404 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
2405 if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
2406 isa<ConstantInt>(Op0I->getOperand(1))) {
2407 // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
2408 Instruction *Add = BinaryOperator::createMul(Op0I->getOperand(0),
2410 InsertNewInstBefore(Add, I);
2411 Value *C1C2 = ConstantExpr::getMul(Op1,
2412 cast<Constant>(Op0I->getOperand(1)));
2413 return BinaryOperator::createAdd(Add, C1C2);
2417 // Try to fold constant mul into select arguments.
2418 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2419 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2422 if (isa<PHINode>(Op0))
2423 if (Instruction *NV = FoldOpIntoPhi(I))
2427 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
2428 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
2429 return BinaryOperator::createMul(Op0v, Op1v);
2431 // If one of the operands of the multiply is a cast from a boolean value, then
2432 // we know the bool is either zero or one, so this is a 'masking' multiply.
2433 // See if we can simplify things based on how the boolean was originally
2435 CastInst *BoolCast = 0;
2436 if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(0)))
2437 if (CI->getOperand(0)->getType() == Type::Int1Ty)
2440 if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(1)))
2441 if (CI->getOperand(0)->getType() == Type::Int1Ty)
2444 if (ICmpInst *SCI = dyn_cast<ICmpInst>(BoolCast->getOperand(0))) {
2445 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
2446 const Type *SCOpTy = SCIOp0->getType();
2449 // If the icmp is true iff the sign bit of X is set, then convert this
2450 // multiply into a shift/and combination.
2451 if (isa<ConstantInt>(SCIOp1) &&
2452 isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1), TIS) &&
2454 // Shift the X value right to turn it into "all signbits".
2455 Constant *Amt = ConstantInt::get(SCIOp0->getType(),
2456 SCOpTy->getPrimitiveSizeInBits()-1);
2458 InsertNewInstBefore(
2459 BinaryOperator::create(Instruction::AShr, SCIOp0, Amt,
2460 BoolCast->getOperand(0)->getName()+
2463 // If the multiply type is not the same as the source type, sign extend
2464 // or truncate to the multiply type.
2465 if (I.getType() != V->getType()) {
2466 uint32_t SrcBits = V->getType()->getPrimitiveSizeInBits();
2467 uint32_t DstBits = I.getType()->getPrimitiveSizeInBits();
2468 Instruction::CastOps opcode =
2469 (SrcBits == DstBits ? Instruction::BitCast :
2470 (SrcBits < DstBits ? Instruction::SExt : Instruction::Trunc));
2471 V = InsertCastBefore(opcode, V, I.getType(), I);
2474 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
2475 return BinaryOperator::createAnd(V, OtherOp);
2480 return Changed ? &I : 0;
2483 /// This function implements the transforms on div instructions that work
2484 /// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
2485 /// used by the visitors to those instructions.
2486 /// @brief Transforms common to all three div instructions
2487 Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
2488 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2491 if (isa<UndefValue>(Op0))
2492 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2494 // X / undef -> undef
2495 if (isa<UndefValue>(Op1))
2496 return ReplaceInstUsesWith(I, Op1);
2498 // Handle cases involving: div X, (select Cond, Y, Z)
2499 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
2500 // div X, (Cond ? 0 : Y) -> div X, Y. If the div and the select are in the
2501 // same basic block, then we replace the select with Y, and the condition
2502 // of the select with false (if the cond value is in the same BB). If the
2503 // select has uses other than the div, this allows them to be simplified
2504 // also. Note that div X, Y is just as good as div X, 0 (undef)
2505 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
2506 if (ST->isNullValue()) {
2507 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
2508 if (CondI && CondI->getParent() == I.getParent())
2509 UpdateValueUsesWith(CondI, ConstantInt::getFalse());
2510 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
2511 I.setOperand(1, SI->getOperand(2));
2513 UpdateValueUsesWith(SI, SI->getOperand(2));
2517 // Likewise for: div X, (Cond ? Y : 0) -> div X, Y
2518 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
2519 if (ST->isNullValue()) {
2520 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
2521 if (CondI && CondI->getParent() == I.getParent())
2522 UpdateValueUsesWith(CondI, ConstantInt::getTrue());
2523 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
2524 I.setOperand(1, SI->getOperand(1));
2526 UpdateValueUsesWith(SI, SI->getOperand(1));
2534 /// This function implements the transforms common to both integer division
2535 /// instructions (udiv and sdiv). It is called by the visitors to those integer
2536 /// division instructions.
2537 /// @brief Common integer divide transforms
2538 Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
2539 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2541 if (Instruction *Common = commonDivTransforms(I))
2544 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2546 if (RHS->equalsInt(1))
2547 return ReplaceInstUsesWith(I, Op0);
2549 // (X / C1) / C2 -> X / (C1*C2)
2550 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
2551 if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
2552 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
2553 return BinaryOperator::create(I.getOpcode(), LHS->getOperand(0),
2554 Multiply(RHS, LHSRHS));
2557 if (!RHS->isZero()) { // avoid X udiv 0
2558 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2559 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2561 if (isa<PHINode>(Op0))
2562 if (Instruction *NV = FoldOpIntoPhi(I))
2567 // 0 / X == 0, we don't need to preserve faults!
2568 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
2569 if (LHS->equalsInt(0))
2570 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2575 Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
2576 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2578 // Handle the integer div common cases
2579 if (Instruction *Common = commonIDivTransforms(I))
2582 // X udiv C^2 -> X >> C
2583 // Check to see if this is an unsigned division with an exact power of 2,
2584 // if so, convert to a right shift.
2585 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
2586 if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
2587 return BinaryOperator::createLShr(Op0,
2588 ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
2591 // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
2592 if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
2593 if (RHSI->getOpcode() == Instruction::Shl &&
2594 isa<ConstantInt>(RHSI->getOperand(0))) {
2595 const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
2596 if (C1.isPowerOf2()) {
2597 Value *N = RHSI->getOperand(1);
2598 const Type *NTy = N->getType();
2599 if (uint32_t C2 = C1.logBase2()) {
2600 Constant *C2V = ConstantInt::get(NTy, C2);
2601 N = InsertNewInstBefore(BinaryOperator::createAdd(N, C2V, "tmp"), I);
2603 return BinaryOperator::createLShr(Op0, N);
2608 // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
2609 // where C1&C2 are powers of two.
2610 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
2611 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
2612 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
2613 const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
2614 if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
2615 // Compute the shift amounts
2616 uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
2617 // Construct the "on true" case of the select
2618 Constant *TC = ConstantInt::get(Op0->getType(), TSA);
2619 Instruction *TSI = BinaryOperator::createLShr(
2620 Op0, TC, SI->getName()+".t");
2621 TSI = InsertNewInstBefore(TSI, I);
2623 // Construct the "on false" case of the select
2624 Constant *FC = ConstantInt::get(Op0->getType(), FSA);
2625 Instruction *FSI = BinaryOperator::createLShr(
2626 Op0, FC, SI->getName()+".f");
2627 FSI = InsertNewInstBefore(FSI, I);
2629 // construct the select instruction and return it.
2630 return new SelectInst(SI->getOperand(0), TSI, FSI, SI->getName());
2636 Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
2637 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2639 // Handle the integer div common cases
2640 if (Instruction *Common = commonIDivTransforms(I))
2643 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2645 if (RHS->isAllOnesValue())
2646 return BinaryOperator::createNeg(Op0);
2649 if (Value *LHSNeg = dyn_castNegVal(Op0))
2650 return BinaryOperator::createSDiv(LHSNeg, ConstantExpr::getNeg(RHS));
2653 // If the sign bits of both operands are zero (i.e. we can prove they are
2654 // unsigned inputs), turn this into a udiv.
2655 if (I.getType()->isInteger()) {
2656 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
2657 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
2658 // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
2659 return BinaryOperator::createUDiv(Op0, Op1, I.getName());
2666 Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
2667 return commonDivTransforms(I);
2670 /// GetFactor - If we can prove that the specified value is at least a multiple
2671 /// of some factor, return that factor.
2672 static Constant *GetFactor(Value *V) {
2673 if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
2676 // Unless we can be tricky, we know this is a multiple of 1.
2677 Constant *Result = ConstantInt::get(V->getType(), 1);
2679 Instruction *I = dyn_cast<Instruction>(V);
2680 if (!I) return Result;
2682 if (I->getOpcode() == Instruction::Mul) {
2683 // Handle multiplies by a constant, etc.
2684 return ConstantExpr::getMul(GetFactor(I->getOperand(0)),
2685 GetFactor(I->getOperand(1)));
2686 } else if (I->getOpcode() == Instruction::Shl) {
2687 // (X<<C) -> X * (1 << C)
2688 if (Constant *ShRHS = dyn_cast<Constant>(I->getOperand(1))) {
2689 ShRHS = ConstantExpr::getShl(Result, ShRHS);
2690 return ConstantExpr::getMul(GetFactor(I->getOperand(0)), ShRHS);
2692 } else if (I->getOpcode() == Instruction::And) {
2693 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
2694 // X & 0xFFF0 is known to be a multiple of 16.
2695 uint32_t Zeros = RHS->getValue().countTrailingZeros();
2696 if (Zeros != V->getType()->getPrimitiveSizeInBits())// don't shift by "32"
2697 return ConstantExpr::getShl(Result,
2698 ConstantInt::get(Result->getType(), Zeros));
2700 } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
2701 // Only handle int->int casts.
2702 if (!CI->isIntegerCast())
2704 Value *Op = CI->getOperand(0);
2705 return ConstantExpr::getCast(CI->getOpcode(), GetFactor(Op), V->getType());
2710 /// This function implements the transforms on rem instructions that work
2711 /// regardless of the kind of rem instruction it is (urem, srem, or frem). It
2712 /// is used by the visitors to those instructions.
2713 /// @brief Transforms common to all three rem instructions
2714 Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
2715 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2717 // 0 % X == 0, we don't need to preserve faults!
2718 if (Constant *LHS = dyn_cast<Constant>(Op0))
2719 if (LHS->isNullValue())
2720 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2722 if (isa<UndefValue>(Op0)) // undef % X -> 0
2723 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2724 if (isa<UndefValue>(Op1))
2725 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
2727 // Handle cases involving: rem X, (select Cond, Y, Z)
2728 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
2729 // rem X, (Cond ? 0 : Y) -> rem X, Y. If the rem and the select are in
2730 // the same basic block, then we replace the select with Y, and the
2731 // condition of the select with false (if the cond value is in the same
2732 // BB). If the select has uses other than the div, this allows them to be
2734 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
2735 if (ST->isNullValue()) {
2736 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
2737 if (CondI && CondI->getParent() == I.getParent())
2738 UpdateValueUsesWith(CondI, ConstantInt::getFalse());
2739 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
2740 I.setOperand(1, SI->getOperand(2));
2742 UpdateValueUsesWith(SI, SI->getOperand(2));
2745 // Likewise for: rem X, (Cond ? Y : 0) -> rem X, Y
2746 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
2747 if (ST->isNullValue()) {
2748 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
2749 if (CondI && CondI->getParent() == I.getParent())
2750 UpdateValueUsesWith(CondI, ConstantInt::getTrue());
2751 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
2752 I.setOperand(1, SI->getOperand(1));
2754 UpdateValueUsesWith(SI, SI->getOperand(1));
2762 /// This function implements the transforms common to both integer remainder
2763 /// instructions (urem and srem). It is called by the visitors to those integer
2764 /// remainder instructions.
2765 /// @brief Common integer remainder transforms
2766 Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
2767 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2769 if (Instruction *common = commonRemTransforms(I))
2772 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2773 // X % 0 == undef, we don't need to preserve faults!
2774 if (RHS->equalsInt(0))
2775 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2777 if (RHS->equalsInt(1)) // X % 1 == 0
2778 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2780 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
2781 if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
2782 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2784 } else if (isa<PHINode>(Op0I)) {
2785 if (Instruction *NV = FoldOpIntoPhi(I))
2788 // (X * C1) % C2 --> 0 iff C1 % C2 == 0
2789 if (ConstantExpr::getSRem(GetFactor(Op0I), RHS)->isNullValue())
2790 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2797 Instruction *InstCombiner::visitURem(BinaryOperator &I) {
2798 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2800 if (Instruction *common = commonIRemTransforms(I))
2803 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2804 // X urem C^2 -> X and C
2805 // Check to see if this is an unsigned remainder with an exact power of 2,
2806 // if so, convert to a bitwise and.
2807 if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
2808 if (C->getValue().isPowerOf2())
2809 return BinaryOperator::createAnd(Op0, SubOne(C));
2812 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
2813 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
2814 if (RHSI->getOpcode() == Instruction::Shl &&
2815 isa<ConstantInt>(RHSI->getOperand(0))) {
2816 if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
2817 Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
2818 Value *Add = InsertNewInstBefore(BinaryOperator::createAdd(RHSI, N1,
2820 return BinaryOperator::createAnd(Op0, Add);
2825 // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
2826 // where C1&C2 are powers of two.
2827 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
2828 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
2829 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
2830 // STO == 0 and SFO == 0 handled above.
2831 if ((STO->getValue().isPowerOf2()) &&
2832 (SFO->getValue().isPowerOf2())) {
2833 Value *TrueAnd = InsertNewInstBefore(
2834 BinaryOperator::createAnd(Op0, SubOne(STO), SI->getName()+".t"), I);
2835 Value *FalseAnd = InsertNewInstBefore(
2836 BinaryOperator::createAnd(Op0, SubOne(SFO), SI->getName()+".f"), I);
2837 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
2845 Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
2846 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2848 // Handle the integer rem common cases
2849 if (Instruction *common = commonIRemTransforms(I))
2852 if (Value *RHSNeg = dyn_castNegVal(Op1))
2853 if (!isa<ConstantInt>(RHSNeg) ||
2854 cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive()) {
2856 AddUsesToWorkList(I);
2857 I.setOperand(1, RHSNeg);
2861 // If the sign bits of both operands are zero (i.e. we can prove they are
2862 // unsigned inputs), turn this into a urem.
2863 if (I.getType()->isInteger()) {
2864 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
2865 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
2866 // X srem Y -> X urem Y, iff X and Y don't have sign bit set
2867 return BinaryOperator::createURem(Op0, Op1, I.getName());
2874 Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
2875 return commonRemTransforms(I);
2878 // isMaxValueMinusOne - return true if this is Max-1
2879 static bool isMaxValueMinusOne(const ConstantInt *C, bool isSigned) {
2880 uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
2882 return C->getValue() == APInt::getAllOnesValue(TypeBits) - 1;
2883 return C->getValue() == APInt::getSignedMaxValue(TypeBits)-1;
2886 // isMinValuePlusOne - return true if this is Min+1
2887 static bool isMinValuePlusOne(const ConstantInt *C, bool isSigned) {
2889 return C->getValue() == 1; // unsigned
2891 // Calculate 1111111111000000000000
2892 uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
2893 return C->getValue() == APInt::getSignedMinValue(TypeBits)+1;
2896 // isOneBitSet - Return true if there is exactly one bit set in the specified
2898 static bool isOneBitSet(const ConstantInt *CI) {
2899 return CI->getValue().isPowerOf2();
2902 // isHighOnes - Return true if the constant is of the form 1+0+.
2903 // This is the same as lowones(~X).
2904 static bool isHighOnes(const ConstantInt *CI) {
2905 return (~CI->getValue() + 1).isPowerOf2();
2908 /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
2909 /// are carefully arranged to allow folding of expressions such as:
2911 /// (A < B) | (A > B) --> (A != B)
2913 /// Note that this is only valid if the first and second predicates have the
2914 /// same sign. Is illegal to do: (A u< B) | (A s> B)
2916 /// Three bits are used to represent the condition, as follows:
2921 /// <=> Value Definition
2922 /// 000 0 Always false
2929 /// 111 7 Always true
2931 static unsigned getICmpCode(const ICmpInst *ICI) {
2932 switch (ICI->getPredicate()) {
2934 case ICmpInst::ICMP_UGT: return 1; // 001
2935 case ICmpInst::ICMP_SGT: return 1; // 001
2936 case ICmpInst::ICMP_EQ: return 2; // 010
2937 case ICmpInst::ICMP_UGE: return 3; // 011
2938 case ICmpInst::ICMP_SGE: return 3; // 011
2939 case ICmpInst::ICMP_ULT: return 4; // 100
2940 case ICmpInst::ICMP_SLT: return 4; // 100
2941 case ICmpInst::ICMP_NE: return 5; // 101
2942 case ICmpInst::ICMP_ULE: return 6; // 110
2943 case ICmpInst::ICMP_SLE: return 6; // 110
2946 assert(0 && "Invalid ICmp predicate!");
2951 /// getICmpValue - This is the complement of getICmpCode, which turns an
2952 /// opcode and two operands into either a constant true or false, or a brand
2953 /// new ICmp instruction. The sign is passed in to determine which kind
2954 /// of predicate to use in new icmp instructions.
2955 static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS) {
2957 default: assert(0 && "Illegal ICmp code!");
2958 case 0: return ConstantInt::getFalse();
2961 return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
2963 return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
2964 case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
2967 return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
2969 return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
2972 return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
2974 return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
2975 case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
2978 return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
2980 return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
2981 case 7: return ConstantInt::getTrue();
2985 static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
2986 return (ICmpInst::isSignedPredicate(p1) == ICmpInst::isSignedPredicate(p2)) ||
2987 (ICmpInst::isSignedPredicate(p1) &&
2988 (p2 == ICmpInst::ICMP_EQ || p2 == ICmpInst::ICMP_NE)) ||
2989 (ICmpInst::isSignedPredicate(p2) &&
2990 (p1 == ICmpInst::ICMP_EQ || p1 == ICmpInst::ICMP_NE));
2994 // FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
2995 struct FoldICmpLogical {
2998 ICmpInst::Predicate pred;
2999 FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
3000 : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
3001 pred(ICI->getPredicate()) {}
3002 bool shouldApply(Value *V) const {
3003 if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
3004 if (PredicatesFoldable(pred, ICI->getPredicate()))
3005 return (ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS ||
3006 ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS);
3009 Instruction *apply(Instruction &Log) const {
3010 ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
3011 if (ICI->getOperand(0) != LHS) {
3012 assert(ICI->getOperand(1) == LHS);
3013 ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
3016 ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
3017 unsigned LHSCode = getICmpCode(ICI);
3018 unsigned RHSCode = getICmpCode(RHSICI);
3020 switch (Log.getOpcode()) {
3021 case Instruction::And: Code = LHSCode & RHSCode; break;
3022 case Instruction::Or: Code = LHSCode | RHSCode; break;
3023 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
3024 default: assert(0 && "Illegal logical opcode!"); return 0;
3027 bool isSigned = ICmpInst::isSignedPredicate(RHSICI->getPredicate()) ||
3028 ICmpInst::isSignedPredicate(ICI->getPredicate());
3030 Value *RV = getICmpValue(isSigned, Code, LHS, RHS);
3031 if (Instruction *I = dyn_cast<Instruction>(RV))
3033 // Otherwise, it's a constant boolean value...
3034 return IC.ReplaceInstUsesWith(Log, RV);
3037 } // end anonymous namespace
3039 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
3040 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
3041 // guaranteed to be a binary operator.
3042 Instruction *InstCombiner::OptAndOp(Instruction *Op,
3044 ConstantInt *AndRHS,
3045 BinaryOperator &TheAnd) {
3046 Value *X = Op->getOperand(0);
3047 Constant *Together = 0;
3049 Together = And(AndRHS, OpRHS);
3051 switch (Op->getOpcode()) {
3052 case Instruction::Xor:
3053 if (Op->hasOneUse()) {
3054 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
3055 Instruction *And = BinaryOperator::createAnd(X, AndRHS);
3056 InsertNewInstBefore(And, TheAnd);
3058 return BinaryOperator::createXor(And, Together);
3061 case Instruction::Or:
3062 if (Together == AndRHS) // (X | C) & C --> C
3063 return ReplaceInstUsesWith(TheAnd, AndRHS);
3065 if (Op->hasOneUse() && Together != OpRHS) {
3066 // (X | C1) & C2 --> (X | (C1&C2)) & C2
3067 Instruction *Or = BinaryOperator::createOr(X, Together);
3068 InsertNewInstBefore(Or, TheAnd);
3070 return BinaryOperator::createAnd(Or, AndRHS);
3073 case Instruction::Add:
3074 if (Op->hasOneUse()) {
3075 // Adding a one to a single bit bit-field should be turned into an XOR
3076 // of the bit. First thing to check is to see if this AND is with a
3077 // single bit constant.
3078 const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
3080 // If there is only one bit set...
3081 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
3082 // Ok, at this point, we know that we are masking the result of the
3083 // ADD down to exactly one bit. If the constant we are adding has
3084 // no bits set below this bit, then we can eliminate the ADD.
3085 const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
3087 // Check to see if any bits below the one bit set in AndRHSV are set.
3088 if ((AddRHS & (AndRHSV-1)) == 0) {
3089 // If not, the only thing that can effect the output of the AND is
3090 // the bit specified by AndRHSV. If that bit is set, the effect of
3091 // the XOR is to toggle the bit. If it is clear, then the ADD has
3093 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
3094 TheAnd.setOperand(0, X);
3097 // Pull the XOR out of the AND.
3098 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS);
3099 InsertNewInstBefore(NewAnd, TheAnd);
3100 NewAnd->takeName(Op);
3101 return BinaryOperator::createXor(NewAnd, AndRHS);
3108 case Instruction::Shl: {
3109 // We know that the AND will not produce any of the bits shifted in, so if
3110 // the anded constant includes them, clear them now!
3112 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3113 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3114 APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
3115 ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShlMask);
3117 if (CI->getValue() == ShlMask) {
3118 // Masking out bits that the shift already masks
3119 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
3120 } else if (CI != AndRHS) { // Reducing bits set in and.
3121 TheAnd.setOperand(1, CI);
3126 case Instruction::LShr:
3128 // We know that the AND will not produce any of the bits shifted in, so if
3129 // the anded constant includes them, clear them now! This only applies to
3130 // unsigned shifts, because a signed shr may bring in set bits!
3132 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3133 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3134 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
3135 ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShrMask);
3137 if (CI->getValue() == ShrMask) {
3138 // Masking out bits that the shift already masks.
3139 return ReplaceInstUsesWith(TheAnd, Op);
3140 } else if (CI != AndRHS) {
3141 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
3146 case Instruction::AShr:
3148 // See if this is shifting in some sign extension, then masking it out
3150 if (Op->hasOneUse()) {
3151 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3152 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3153 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
3154 Constant *C = ConstantInt::get(AndRHS->getValue() & ShrMask);
3155 if (C == AndRHS) { // Masking out bits shifted in.
3156 // (Val ashr C1) & C2 -> (Val lshr C1) & C2
3157 // Make the argument unsigned.
3158 Value *ShVal = Op->getOperand(0);
3159 ShVal = InsertNewInstBefore(
3160 BinaryOperator::createLShr(ShVal, OpRHS,
3161 Op->getName()), TheAnd);
3162 return BinaryOperator::createAnd(ShVal, AndRHS, TheAnd.getName());
3171 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
3172 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
3173 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
3174 /// whether to treat the V, Lo and HI as signed or not. IB is the location to
3175 /// insert new instructions.
3176 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
3177 bool isSigned, bool Inside,
3179 assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
3180 ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
3181 "Lo is not <= Hi in range emission code!");
3184 if (Lo == Hi) // Trivially false.
3185 return new ICmpInst(ICmpInst::ICMP_NE, V, V);
3187 // V >= Min && V < Hi --> V < Hi
3188 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
3189 ICmpInst::Predicate pred = (isSigned ?
3190 ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
3191 return new ICmpInst(pred, V, Hi);
3194 // Emit V-Lo <u Hi-Lo
3195 Constant *NegLo = ConstantExpr::getNeg(Lo);
3196 Instruction *Add = BinaryOperator::createAdd(V, NegLo, V->getName()+".off");
3197 InsertNewInstBefore(Add, IB);
3198 Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
3199 return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
3202 if (Lo == Hi) // Trivially true.
3203 return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
3205 // V < Min || V >= Hi -> V > Hi-1
3206 Hi = SubOne(cast<ConstantInt>(Hi));
3207 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
3208 ICmpInst::Predicate pred = (isSigned ?
3209 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
3210 return new ICmpInst(pred, V, Hi);
3213 // Emit V-Lo >u Hi-1-Lo
3214 // Note that Hi has already had one subtracted from it, above.
3215 ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
3216 Instruction *Add = BinaryOperator::createAdd(V, NegLo, V->getName()+".off");
3217 InsertNewInstBefore(Add, IB);
3218 Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
3219 return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
3222 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
3223 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
3224 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
3225 // not, since all 1s are not contiguous.
3226 static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
3227 const APInt& V = Val->getValue();
3228 uint32_t BitWidth = Val->getType()->getBitWidth();
3229 if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
3231 // look for the first zero bit after the run of ones
3232 MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
3233 // look for the first non-zero bit
3234 ME = V.getActiveBits();
3238 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
3239 /// where isSub determines whether the operator is a sub. If we can fold one of
3240 /// the following xforms:
3242 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
3243 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
3244 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
3246 /// return (A +/- B).
3248 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
3249 ConstantInt *Mask, bool isSub,
3251 Instruction *LHSI = dyn_cast<Instruction>(LHS);
3252 if (!LHSI || LHSI->getNumOperands() != 2 ||
3253 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
3255 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
3257 switch (LHSI->getOpcode()) {
3259 case Instruction::And:
3260 if (And(N, Mask) == Mask) {
3261 // If the AndRHS is a power of two minus one (0+1+), this is simple.
3262 if ((Mask->getValue().countLeadingZeros() +
3263 Mask->getValue().countPopulation()) ==
3264 Mask->getValue().getBitWidth())
3267 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
3268 // part, we don't need any explicit masks to take them out of A. If that
3269 // is all N is, ignore it.
3270 uint32_t MB = 0, ME = 0;
3271 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
3272 uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
3273 APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
3274 if (MaskedValueIsZero(RHS, Mask))
3279 case Instruction::Or:
3280 case Instruction::Xor:
3281 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
3282 if ((Mask->getValue().countLeadingZeros() +
3283 Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
3284 && And(N, Mask)->isZero())
3291 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
3293 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
3294 return InsertNewInstBefore(New, I);
3297 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
3298 bool Changed = SimplifyCommutative(I);
3299 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3301 if (isa<UndefValue>(Op1)) // X & undef -> 0
3302 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3306 return ReplaceInstUsesWith(I, Op1);
3308 // See if we can simplify any instructions used by the instruction whose sole
3309 // purpose is to compute bits we don't care about.
3310 if (!isa<VectorType>(I.getType())) {
3311 uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
3312 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
3313 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
3314 KnownZero, KnownOne))
3317 if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
3318 if (CP->isAllOnesValue()) // X & <-1,-1> -> X
3319 return ReplaceInstUsesWith(I, I.getOperand(0));
3320 } else if (isa<ConstantAggregateZero>(Op1)) {
3321 return ReplaceInstUsesWith(I, Op1); // X & <0,0> -> <0,0>
3325 if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
3326 const APInt& AndRHSMask = AndRHS->getValue();
3327 APInt NotAndRHS(~AndRHSMask);
3329 // Optimize a variety of ((val OP C1) & C2) combinations...
3330 if (isa<BinaryOperator>(Op0)) {
3331 Instruction *Op0I = cast<Instruction>(Op0);
3332 Value *Op0LHS = Op0I->getOperand(0);
3333 Value *Op0RHS = Op0I->getOperand(1);
3334 switch (Op0I->getOpcode()) {
3335 case Instruction::Xor:
3336 case Instruction::Or:
3337 // If the mask is only needed on one incoming arm, push it up.
3338 if (Op0I->hasOneUse()) {
3339 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
3340 // Not masking anything out for the LHS, move to RHS.
3341 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
3342 Op0RHS->getName()+".masked");
3343 InsertNewInstBefore(NewRHS, I);
3344 return BinaryOperator::create(
3345 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
3347 if (!isa<Constant>(Op0RHS) &&
3348 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
3349 // Not masking anything out for the RHS, move to LHS.
3350 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
3351 Op0LHS->getName()+".masked");
3352 InsertNewInstBefore(NewLHS, I);
3353 return BinaryOperator::create(
3354 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
3359 case Instruction::Add:
3360 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
3361 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
3362 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
3363 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
3364 return BinaryOperator::createAnd(V, AndRHS);
3365 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
3366 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
3369 case Instruction::Sub:
3370 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
3371 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
3372 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
3373 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
3374 return BinaryOperator::createAnd(V, AndRHS);
3378 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
3379 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
3381 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3382 // If this is an integer truncation or change from signed-to-unsigned, and
3383 // if the source is an and/or with immediate, transform it. This
3384 // frequently occurs for bitfield accesses.
3385 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
3386 if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
3387 CastOp->getNumOperands() == 2)
3388 if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1)))
3389 if (CastOp->getOpcode() == Instruction::And) {
3390 // Change: and (cast (and X, C1) to T), C2
3391 // into : and (cast X to T), trunc_or_bitcast(C1)&C2
3392 // This will fold the two constants together, which may allow
3393 // other simplifications.
3394 Instruction *NewCast = CastInst::createTruncOrBitCast(
3395 CastOp->getOperand(0), I.getType(),
3396 CastOp->getName()+".shrunk");
3397 NewCast = InsertNewInstBefore(NewCast, I);
3398 // trunc_or_bitcast(C1)&C2
3399 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
3400 C3 = ConstantExpr::getAnd(C3, AndRHS);
3401 return BinaryOperator::createAnd(NewCast, C3);
3402 } else if (CastOp->getOpcode() == Instruction::Or) {
3403 // Change: and (cast (or X, C1) to T), C2
3404 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
3405 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
3406 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
3407 return ReplaceInstUsesWith(I, AndRHS);
3412 // Try to fold constant and into select arguments.
3413 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3414 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3416 if (isa<PHINode>(Op0))
3417 if (Instruction *NV = FoldOpIntoPhi(I))
3421 Value *Op0NotVal = dyn_castNotVal(Op0);
3422 Value *Op1NotVal = dyn_castNotVal(Op1);
3424 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
3425 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3427 // (~A & ~B) == (~(A | B)) - De Morgan's Law
3428 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
3429 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
3430 I.getName()+".demorgan");
3431 InsertNewInstBefore(Or, I);
3432 return BinaryOperator::createNot(Or);
3436 Value *A = 0, *B = 0, *C = 0, *D = 0;
3437 if (match(Op0, m_Or(m_Value(A), m_Value(B)))) {
3438 if (A == Op1 || B == Op1) // (A | ?) & A --> A
3439 return ReplaceInstUsesWith(I, Op1);
3441 // (A|B) & ~(A&B) -> A^B
3442 if (match(Op1, m_Not(m_And(m_Value(C), m_Value(D))))) {
3443 if ((A == C && B == D) || (A == D && B == C))
3444 return BinaryOperator::createXor(A, B);
3448 if (match(Op1, m_Or(m_Value(A), m_Value(B)))) {
3449 if (A == Op0 || B == Op0) // A & (A | ?) --> A
3450 return ReplaceInstUsesWith(I, Op0);
3452 // ~(A&B) & (A|B) -> A^B
3453 if (match(Op0, m_Not(m_And(m_Value(C), m_Value(D))))) {
3454 if ((A == C && B == D) || (A == D && B == C))
3455 return BinaryOperator::createXor(A, B);
3459 if (Op0->hasOneUse() &&
3460 match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
3461 if (A == Op1) { // (A^B)&A -> A&(A^B)
3462 I.swapOperands(); // Simplify below
3463 std::swap(Op0, Op1);
3464 } else if (B == Op1) { // (A^B)&B -> B&(B^A)
3465 cast<BinaryOperator>(Op0)->swapOperands();
3466 I.swapOperands(); // Simplify below
3467 std::swap(Op0, Op1);
3470 if (Op1->hasOneUse() &&
3471 match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
3472 if (B == Op0) { // B&(A^B) -> B&(B^A)
3473 cast<BinaryOperator>(Op1)->swapOperands();
3476 if (A == Op0) { // A&(A^B) -> A & ~B
3477 Instruction *NotB = BinaryOperator::createNot(B, "tmp");
3478 InsertNewInstBefore(NotB, I);
3479 return BinaryOperator::createAnd(A, NotB);
3484 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
3485 // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
3486 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
3489 Value *LHSVal, *RHSVal;
3490 ConstantInt *LHSCst, *RHSCst;
3491 ICmpInst::Predicate LHSCC, RHSCC;
3492 if (match(Op0, m_ICmp(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
3493 if (match(RHS, m_ICmp(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
3494 if (LHSVal == RHSVal && // Found (X icmp C1) & (X icmp C2)
3495 // ICMP_[GL]E X, CST is folded to ICMP_[GL]T elsewhere.
3496 LHSCC != ICmpInst::ICMP_UGE && LHSCC != ICmpInst::ICMP_ULE &&
3497 RHSCC != ICmpInst::ICMP_UGE && RHSCC != ICmpInst::ICMP_ULE &&
3498 LHSCC != ICmpInst::ICMP_SGE && LHSCC != ICmpInst::ICMP_SLE &&
3499 RHSCC != ICmpInst::ICMP_SGE && RHSCC != ICmpInst::ICMP_SLE &&
3501 // Don't try to fold ICMP_SLT + ICMP_ULT.
3502 (ICmpInst::isEquality(LHSCC) || ICmpInst::isEquality(RHSCC) ||
3503 ICmpInst::isSignedPredicate(LHSCC) ==
3504 ICmpInst::isSignedPredicate(RHSCC))) {
3505 // Ensure that the larger constant is on the RHS.
3506 ICmpInst::Predicate GT = ICmpInst::isSignedPredicate(LHSCC) ?
3507 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
3508 Constant *Cmp = ConstantExpr::getICmp(GT, LHSCst, RHSCst);
3509 ICmpInst *LHS = cast<ICmpInst>(Op0);
3510 if (cast<ConstantInt>(Cmp)->getZExtValue()) {
3511 std::swap(LHS, RHS);
3512 std::swap(LHSCst, RHSCst);
3513 std::swap(LHSCC, RHSCC);
3516 // At this point, we know we have have two icmp instructions
3517 // comparing a value against two constants and and'ing the result
3518 // together. Because of the above check, we know that we only have
3519 // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
3520 // (from the FoldICmpLogical check above), that the two constants
3521 // are not equal and that the larger constant is on the RHS
3522 assert(LHSCst != RHSCst && "Compares not folded above?");
3525 default: assert(0 && "Unknown integer condition code!");
3526 case ICmpInst::ICMP_EQ:
3528 default: assert(0 && "Unknown integer condition code!");
3529 case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
3530 case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
3531 case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
3532 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
3533 case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
3534 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
3535 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
3536 return ReplaceInstUsesWith(I, LHS);
3538 case ICmpInst::ICMP_NE:
3540 default: assert(0 && "Unknown integer condition code!");
3541 case ICmpInst::ICMP_ULT:
3542 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
3543 return new ICmpInst(ICmpInst::ICMP_ULT, LHSVal, LHSCst);
3544 break; // (X != 13 & X u< 15) -> no change
3545 case ICmpInst::ICMP_SLT:
3546 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
3547 return new ICmpInst(ICmpInst::ICMP_SLT, LHSVal, LHSCst);
3548 break; // (X != 13 & X s< 15) -> no change
3549 case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
3550 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
3551 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
3552 return ReplaceInstUsesWith(I, RHS);
3553 case ICmpInst::ICMP_NE:
3554 if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
3555 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
3556 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
3557 LHSVal->getName()+".off");
3558 InsertNewInstBefore(Add, I);
3559 return new ICmpInst(ICmpInst::ICMP_UGT, Add,
3560 ConstantInt::get(Add->getType(), 1));
3562 break; // (X != 13 & X != 15) -> no change
3565 case ICmpInst::ICMP_ULT:
3567 default: assert(0 && "Unknown integer condition code!");
3568 case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
3569 case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
3570 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
3571 case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
3573 case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
3574 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
3575 return ReplaceInstUsesWith(I, LHS);
3576 case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
3580 case ICmpInst::ICMP_SLT:
3582 default: assert(0 && "Unknown integer condition code!");
3583 case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
3584 case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
3585 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
3586 case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
3588 case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
3589 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
3590 return ReplaceInstUsesWith(I, LHS);
3591 case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
3595 case ICmpInst::ICMP_UGT:
3597 default: assert(0 && "Unknown integer condition code!");
3598 case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X > 13
3599 return ReplaceInstUsesWith(I, LHS);
3600 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
3601 return ReplaceInstUsesWith(I, RHS);
3602 case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
3604 case ICmpInst::ICMP_NE:
3605 if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
3606 return new ICmpInst(LHSCC, LHSVal, RHSCst);
3607 break; // (X u> 13 & X != 15) -> no change
3608 case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) ->(X-14) <u 1
3609 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, false,
3611 case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
3615 case ICmpInst::ICMP_SGT:
3617 default: assert(0 && "Unknown integer condition code!");
3618 case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15
3619 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
3620 return ReplaceInstUsesWith(I, RHS);
3621 case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
3623 case ICmpInst::ICMP_NE:
3624 if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
3625 return new ICmpInst(LHSCC, LHSVal, RHSCst);
3626 break; // (X s> 13 & X != 15) -> no change
3627 case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) ->(X-14) s< 1
3628 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true,
3630 case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
3638 // fold (and (cast A), (cast B)) -> (cast (and A, B))
3639 if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
3640 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
3641 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
3642 const Type *SrcTy = Op0C->getOperand(0)->getType();
3643 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
3644 // Only do this if the casts both really cause code to be generated.
3645 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
3647 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
3649 Instruction *NewOp = BinaryOperator::createAnd(Op0C->getOperand(0),
3650 Op1C->getOperand(0),
3652 InsertNewInstBefore(NewOp, I);
3653 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
3657 // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
3658 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
3659 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
3660 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
3661 SI0->getOperand(1) == SI1->getOperand(1) &&
3662 (SI0->hasOneUse() || SI1->hasOneUse())) {
3663 Instruction *NewOp =
3664 InsertNewInstBefore(BinaryOperator::createAnd(SI0->getOperand(0),
3666 SI0->getName()), I);
3667 return BinaryOperator::create(SI1->getOpcode(), NewOp,
3668 SI1->getOperand(1));
3672 // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
3673 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
3674 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) {
3675 if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
3676 RHS->getPredicate() == FCmpInst::FCMP_ORD)
3677 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
3678 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
3679 // If either of the constants are nans, then the whole thing returns
3681 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
3682 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
3683 return new FCmpInst(FCmpInst::FCMP_ORD, LHS->getOperand(0),
3684 RHS->getOperand(0));
3689 return Changed ? &I : 0;
3692 /// CollectBSwapParts - Look to see if the specified value defines a single byte
3693 /// in the result. If it does, and if the specified byte hasn't been filled in
3694 /// yet, fill it in and return false.
3695 static bool CollectBSwapParts(Value *V, SmallVector<Value*, 8> &ByteValues) {
3696 Instruction *I = dyn_cast<Instruction>(V);
3697 if (I == 0) return true;
3699 // If this is an or instruction, it is an inner node of the bswap.
3700 if (I->getOpcode() == Instruction::Or)
3701 return CollectBSwapParts(I->getOperand(0), ByteValues) ||
3702 CollectBSwapParts(I->getOperand(1), ByteValues);
3704 uint32_t BitWidth = I->getType()->getPrimitiveSizeInBits();
3705 // If this is a shift by a constant int, and it is "24", then its operand
3706 // defines a byte. We only handle unsigned types here.
3707 if (I->isShift() && isa<ConstantInt>(I->getOperand(1))) {
3708 // Not shifting the entire input by N-1 bytes?
3709 if (cast<ConstantInt>(I->getOperand(1))->getLimitedValue(BitWidth) !=
3710 8*(ByteValues.size()-1))
3714 if (I->getOpcode() == Instruction::Shl) {
3715 // X << 24 defines the top byte with the lowest of the input bytes.
3716 DestNo = ByteValues.size()-1;
3718 // X >>u 24 defines the low byte with the highest of the input bytes.
3722 // If the destination byte value is already defined, the values are or'd
3723 // together, which isn't a bswap (unless it's an or of the same bits).
3724 if (ByteValues[DestNo] && ByteValues[DestNo] != I->getOperand(0))
3726 ByteValues[DestNo] = I->getOperand(0);
3730 // Otherwise, we can only handle and(shift X, imm), imm). Bail out of if we
3732 Value *Shift = 0, *ShiftLHS = 0;
3733 ConstantInt *AndAmt = 0, *ShiftAmt = 0;
3734 if (!match(I, m_And(m_Value(Shift), m_ConstantInt(AndAmt))) ||
3735 !match(Shift, m_Shift(m_Value(ShiftLHS), m_ConstantInt(ShiftAmt))))
3737 Instruction *SI = cast<Instruction>(Shift);
3739 // Make sure that the shift amount is by a multiple of 8 and isn't too big.
3740 if (ShiftAmt->getLimitedValue(BitWidth) & 7 ||
3741 ShiftAmt->getLimitedValue(BitWidth) > 8*ByteValues.size())
3744 // Turn 0xFF -> 0, 0xFF00 -> 1, 0xFF0000 -> 2, etc.
3746 if (AndAmt->getValue().getActiveBits() > 64)
3748 uint64_t AndAmtVal = AndAmt->getZExtValue();
3749 for (DestByte = 0; DestByte != ByteValues.size(); ++DestByte)
3750 if (AndAmtVal == uint64_t(0xFF) << 8*DestByte)
3752 // Unknown mask for bswap.
3753 if (DestByte == ByteValues.size()) return true;
3755 unsigned ShiftBytes = ShiftAmt->getZExtValue()/8;
3757 if (SI->getOpcode() == Instruction::Shl)
3758 SrcByte = DestByte - ShiftBytes;
3760 SrcByte = DestByte + ShiftBytes;
3762 // If the SrcByte isn't a bswapped value from the DestByte, reject it.
3763 if (SrcByte != ByteValues.size()-DestByte-1)
3766 // If the destination byte value is already defined, the values are or'd
3767 // together, which isn't a bswap (unless it's an or of the same bits).
3768 if (ByteValues[DestByte] && ByteValues[DestByte] != SI->getOperand(0))
3770 ByteValues[DestByte] = SI->getOperand(0);
3774 /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
3775 /// If so, insert the new bswap intrinsic and return it.
3776 Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
3777 const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
3778 if (!ITy || ITy->getBitWidth() % 16)
3779 return 0; // Can only bswap pairs of bytes. Can't do vectors.
3781 /// ByteValues - For each byte of the result, we keep track of which value
3782 /// defines each byte.
3783 SmallVector<Value*, 8> ByteValues;
3784 ByteValues.resize(ITy->getBitWidth()/8);
3786 // Try to find all the pieces corresponding to the bswap.
3787 if (CollectBSwapParts(I.getOperand(0), ByteValues) ||
3788 CollectBSwapParts(I.getOperand(1), ByteValues))
3791 // Check to see if all of the bytes come from the same value.
3792 Value *V = ByteValues[0];
3793 if (V == 0) return 0; // Didn't find a byte? Must be zero.
3795 // Check to make sure that all of the bytes come from the same value.
3796 for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
3797 if (ByteValues[i] != V)
3799 const Type *Tys[] = { ITy };
3800 Module *M = I.getParent()->getParent()->getParent();
3801 Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
3802 return new CallInst(F, V);
3806 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
3807 bool Changed = SimplifyCommutative(I);
3808 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3810 if (isa<UndefValue>(Op1)) // X | undef -> -1
3811 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
3815 return ReplaceInstUsesWith(I, Op0);
3817 // See if we can simplify any instructions used by the instruction whose sole
3818 // purpose is to compute bits we don't care about.
3819 if (!isa<VectorType>(I.getType())) {
3820 uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
3821 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
3822 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
3823 KnownZero, KnownOne))
3825 } else if (isa<ConstantAggregateZero>(Op1)) {
3826 return ReplaceInstUsesWith(I, Op0); // X | <0,0> -> X
3827 } else if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
3828 if (CP->isAllOnesValue()) // X | <-1,-1> -> <-1,-1>
3829 return ReplaceInstUsesWith(I, I.getOperand(1));
3835 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3836 ConstantInt *C1 = 0; Value *X = 0;
3837 // (X & C1) | C2 --> (X | C2) & (C1|C2)
3838 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
3839 Instruction *Or = BinaryOperator::createOr(X, RHS);
3840 InsertNewInstBefore(Or, I);
3842 return BinaryOperator::createAnd(Or,
3843 ConstantInt::get(RHS->getValue() | C1->getValue()));
3846 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
3847 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
3848 Instruction *Or = BinaryOperator::createOr(X, RHS);
3849 InsertNewInstBefore(Or, I);
3851 return BinaryOperator::createXor(Or,
3852 ConstantInt::get(C1->getValue() & ~RHS->getValue()));
3855 // Try to fold constant and into select arguments.
3856 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3857 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3859 if (isa<PHINode>(Op0))
3860 if (Instruction *NV = FoldOpIntoPhi(I))
3864 Value *A = 0, *B = 0;
3865 ConstantInt *C1 = 0, *C2 = 0;
3867 if (match(Op0, m_And(m_Value(A), m_Value(B))))
3868 if (A == Op1 || B == Op1) // (A & ?) | A --> A
3869 return ReplaceInstUsesWith(I, Op1);
3870 if (match(Op1, m_And(m_Value(A), m_Value(B))))
3871 if (A == Op0 || B == Op0) // A | (A & ?) --> A
3872 return ReplaceInstUsesWith(I, Op0);
3874 // (A | B) | C and A | (B | C) -> bswap if possible.
3875 // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
3876 if (match(Op0, m_Or(m_Value(), m_Value())) ||
3877 match(Op1, m_Or(m_Value(), m_Value())) ||
3878 (match(Op0, m_Shift(m_Value(), m_Value())) &&
3879 match(Op1, m_Shift(m_Value(), m_Value())))) {
3880 if (Instruction *BSwap = MatchBSwap(I))
3884 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
3885 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
3886 MaskedValueIsZero(Op1, C1->getValue())) {
3887 Instruction *NOr = BinaryOperator::createOr(A, Op1);
3888 InsertNewInstBefore(NOr, I);
3890 return BinaryOperator::createXor(NOr, C1);
3893 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
3894 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
3895 MaskedValueIsZero(Op0, C1->getValue())) {
3896 Instruction *NOr = BinaryOperator::createOr(A, Op0);
3897 InsertNewInstBefore(NOr, I);
3899 return BinaryOperator::createXor(NOr, C1);
3903 Value *C = 0, *D = 0;
3904 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
3905 match(Op1, m_And(m_Value(B), m_Value(D)))) {
3906 Value *V1 = 0, *V2 = 0, *V3 = 0;
3907 C1 = dyn_cast<ConstantInt>(C);
3908 C2 = dyn_cast<ConstantInt>(D);
3909 if (C1 && C2) { // (A & C1)|(B & C2)
3910 // If we have: ((V + N) & C1) | (V & C2)
3911 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
3912 // replace with V+N.
3913 if (C1->getValue() == ~C2->getValue()) {
3914 if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
3915 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
3916 // Add commutes, try both ways.
3917 if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
3918 return ReplaceInstUsesWith(I, A);
3919 if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
3920 return ReplaceInstUsesWith(I, A);
3922 // Or commutes, try both ways.
3923 if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
3924 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
3925 // Add commutes, try both ways.
3926 if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
3927 return ReplaceInstUsesWith(I, B);
3928 if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
3929 return ReplaceInstUsesWith(I, B);
3932 V1 = 0; V2 = 0; V3 = 0;
3935 // Check to see if we have any common things being and'ed. If so, find the
3936 // terms for V1 & (V2|V3).
3937 if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
3938 if (A == B) // (A & C)|(A & D) == A & (C|D)
3939 V1 = A, V2 = C, V3 = D;
3940 else if (A == D) // (A & C)|(B & A) == A & (B|C)
3941 V1 = A, V2 = B, V3 = C;
3942 else if (C == B) // (A & C)|(C & D) == C & (A|D)
3943 V1 = C, V2 = A, V3 = D;
3944 else if (C == D) // (A & C)|(B & C) == C & (A|B)
3945 V1 = C, V2 = A, V3 = B;
3949 InsertNewInstBefore(BinaryOperator::createOr(V2, V3, "tmp"), I);
3950 return BinaryOperator::createAnd(V1, Or);
3955 // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
3956 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
3957 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
3958 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
3959 SI0->getOperand(1) == SI1->getOperand(1) &&
3960 (SI0->hasOneUse() || SI1->hasOneUse())) {
3961 Instruction *NewOp =
3962 InsertNewInstBefore(BinaryOperator::createOr(SI0->getOperand(0),
3964 SI0->getName()), I);
3965 return BinaryOperator::create(SI1->getOpcode(), NewOp,
3966 SI1->getOperand(1));
3970 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
3971 if (A == Op1) // ~A | A == -1
3972 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
3976 // Note, A is still live here!
3977 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
3979 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
3981 // (~A | ~B) == (~(A & B)) - De Morgan's Law
3982 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
3983 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
3984 I.getName()+".demorgan"), I);
3985 return BinaryOperator::createNot(And);
3989 // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
3990 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
3991 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
3994 Value *LHSVal, *RHSVal;
3995 ConstantInt *LHSCst, *RHSCst;
3996 ICmpInst::Predicate LHSCC, RHSCC;
3997 if (match(Op0, m_ICmp(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
3998 if (match(RHS, m_ICmp(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
3999 if (LHSVal == RHSVal && // Found (X icmp C1) | (X icmp C2)
4000 // icmp [us][gl]e x, cst is folded to icmp [us][gl]t elsewhere.
4001 LHSCC != ICmpInst::ICMP_UGE && LHSCC != ICmpInst::ICMP_ULE &&
4002 RHSCC != ICmpInst::ICMP_UGE && RHSCC != ICmpInst::ICMP_ULE &&
4003 LHSCC != ICmpInst::ICMP_SGE && LHSCC != ICmpInst::ICMP_SLE &&
4004 RHSCC != ICmpInst::ICMP_SGE && RHSCC != ICmpInst::ICMP_SLE &&
4005 // We can't fold (ugt x, C) | (sgt x, C2).
4006 PredicatesFoldable(LHSCC, RHSCC)) {
4007 // Ensure that the larger constant is on the RHS.
4008 ICmpInst *LHS = cast<ICmpInst>(Op0);
4010 if (ICmpInst::isSignedPredicate(LHSCC))
4011 NeedsSwap = LHSCst->getValue().sgt(RHSCst->getValue());
4013 NeedsSwap = LHSCst->getValue().ugt(RHSCst->getValue());
4016 std::swap(LHS, RHS);
4017 std::swap(LHSCst, RHSCst);
4018 std::swap(LHSCC, RHSCC);
4021 // At this point, we know we have have two icmp instructions
4022 // comparing a value against two constants and or'ing the result
4023 // together. Because of the above check, we know that we only have
4024 // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
4025 // FoldICmpLogical check above), that the two constants are not
4027 assert(LHSCst != RHSCst && "Compares not folded above?");
4030 default: assert(0 && "Unknown integer condition code!");
4031 case ICmpInst::ICMP_EQ:
4033 default: assert(0 && "Unknown integer condition code!");
4034 case ICmpInst::ICMP_EQ:
4035 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
4036 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
4037 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
4038 LHSVal->getName()+".off");
4039 InsertNewInstBefore(Add, I);
4040 AddCST = Subtract(AddOne(RHSCst), LHSCst);
4041 return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
4043 break; // (X == 13 | X == 15) -> no change
4044 case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
4045 case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
4047 case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
4048 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
4049 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
4050 return ReplaceInstUsesWith(I, RHS);
4053 case ICmpInst::ICMP_NE:
4055 default: assert(0 && "Unknown integer condition code!");
4056 case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
4057 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
4058 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
4059 return ReplaceInstUsesWith(I, LHS);
4060 case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
4061 case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
4062 case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
4063 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4066 case ICmpInst::ICMP_ULT:
4068 default: assert(0 && "Unknown integer condition code!");
4069 case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
4071 case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) ->(X-13) u> 2
4072 // If RHSCst is [us]MAXINT, it is always false. Not handling
4073 // this can cause overflow.
4074 if (RHSCst->isMaxValue(false))
4075 return ReplaceInstUsesWith(I, LHS);
4076 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false,
4078 case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
4080 case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
4081 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
4082 return ReplaceInstUsesWith(I, RHS);
4083 case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
4087 case ICmpInst::ICMP_SLT:
4089 default: assert(0 && "Unknown integer condition code!");
4090 case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
4092 case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) ->(X-13) s> 2
4093 // If RHSCst is [us]MAXINT, it is always false. Not handling
4094 // this can cause overflow.
4095 if (RHSCst->isMaxValue(true))
4096 return ReplaceInstUsesWith(I, LHS);
4097 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), true,
4099 case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
4101 case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
4102 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
4103 return ReplaceInstUsesWith(I, RHS);
4104 case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
4108 case ICmpInst::ICMP_UGT:
4110 default: assert(0 && "Unknown integer condition code!");
4111 case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
4112 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
4113 return ReplaceInstUsesWith(I, LHS);
4114 case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
4116 case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
4117 case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
4118 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4119 case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
4123 case ICmpInst::ICMP_SGT:
4125 default: assert(0 && "Unknown integer condition code!");
4126 case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
4127 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
4128 return ReplaceInstUsesWith(I, LHS);
4129 case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
4131 case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
4132 case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
4133 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4134 case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
4142 // fold (or (cast A), (cast B)) -> (cast (or A, B))
4143 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
4144 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
4145 if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
4146 const Type *SrcTy = Op0C->getOperand(0)->getType();
4147 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
4148 // Only do this if the casts both really cause code to be generated.
4149 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
4151 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
4153 Instruction *NewOp = BinaryOperator::createOr(Op0C->getOperand(0),
4154 Op1C->getOperand(0),
4156 InsertNewInstBefore(NewOp, I);
4157 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
4163 // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
4164 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
4165 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) {
4166 if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
4167 RHS->getPredicate() == FCmpInst::FCMP_UNO)
4168 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
4169 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
4170 // If either of the constants are nans, then the whole thing returns
4172 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
4173 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4175 // Otherwise, no need to compare the two constants, compare the
4177 return new FCmpInst(FCmpInst::FCMP_UNO, LHS->getOperand(0),
4178 RHS->getOperand(0));
4183 return Changed ? &I : 0;
4186 // XorSelf - Implements: X ^ X --> 0
4189 XorSelf(Value *rhs) : RHS(rhs) {}
4190 bool shouldApply(Value *LHS) const { return LHS == RHS; }
4191 Instruction *apply(BinaryOperator &Xor) const {
4197 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
4198 bool Changed = SimplifyCommutative(I);
4199 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4201 if (isa<UndefValue>(Op1))
4202 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
4204 // xor X, X = 0, even if X is nested in a sequence of Xor's.
4205 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
4206 assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
4207 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4210 // See if we can simplify any instructions used by the instruction whose sole
4211 // purpose is to compute bits we don't care about.
4212 if (!isa<VectorType>(I.getType())) {
4213 uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
4214 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
4215 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
4216 KnownZero, KnownOne))
4218 } else if (isa<ConstantAggregateZero>(Op1)) {
4219 return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X
4222 // Is this a ~ operation?
4223 if (Value *NotOp = dyn_castNotVal(&I)) {
4224 // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
4225 // ~(~X | Y) === (X & ~Y) - De Morgan's Law
4226 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
4227 if (Op0I->getOpcode() == Instruction::And ||
4228 Op0I->getOpcode() == Instruction::Or) {
4229 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
4230 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
4232 BinaryOperator::createNot(Op0I->getOperand(1),
4233 Op0I->getOperand(1)->getName()+".not");
4234 InsertNewInstBefore(NotY, I);
4235 if (Op0I->getOpcode() == Instruction::And)
4236 return BinaryOperator::createOr(Op0NotVal, NotY);
4238 return BinaryOperator::createAnd(Op0NotVal, NotY);
4245 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
4246 // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
4247 if (RHS == ConstantInt::getTrue() && Op0->hasOneUse()) {
4248 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
4249 return new ICmpInst(ICI->getInversePredicate(),
4250 ICI->getOperand(0), ICI->getOperand(1));
4252 if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
4253 return new FCmpInst(FCI->getInversePredicate(),
4254 FCI->getOperand(0), FCI->getOperand(1));
4257 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
4258 // ~(c-X) == X-c-1 == X+(-c-1)
4259 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
4260 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
4261 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
4262 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
4263 ConstantInt::get(I.getType(), 1));
4264 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
4267 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
4268 if (Op0I->getOpcode() == Instruction::Add) {
4269 // ~(X-c) --> (-c-1)-X
4270 if (RHS->isAllOnesValue()) {
4271 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
4272 return BinaryOperator::createSub(
4273 ConstantExpr::getSub(NegOp0CI,
4274 ConstantInt::get(I.getType(), 1)),
4275 Op0I->getOperand(0));
4276 } else if (RHS->getValue().isSignBit()) {
4277 // (X + C) ^ signbit -> (X + C + signbit)
4278 Constant *C = ConstantInt::get(RHS->getValue() + Op0CI->getValue());
4279 return BinaryOperator::createAdd(Op0I->getOperand(0), C);
4282 } else if (Op0I->getOpcode() == Instruction::Or) {
4283 // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
4284 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
4285 Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
4286 // Anything in both C1 and C2 is known to be zero, remove it from
4288 Constant *CommonBits = And(Op0CI, RHS);
4289 NewRHS = ConstantExpr::getAnd(NewRHS,
4290 ConstantExpr::getNot(CommonBits));
4291 AddToWorkList(Op0I);
4292 I.setOperand(0, Op0I->getOperand(0));
4293 I.setOperand(1, NewRHS);
4299 // Try to fold constant and into select arguments.
4300 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
4301 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
4303 if (isa<PHINode>(Op0))
4304 if (Instruction *NV = FoldOpIntoPhi(I))
4308 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
4310 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
4312 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
4314 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
4317 BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
4320 if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
4321 if (A == Op0) { // B^(B|A) == (A|B)^B
4322 Op1I->swapOperands();
4324 std::swap(Op0, Op1);
4325 } else if (B == Op0) { // B^(A|B) == (A|B)^B
4326 I.swapOperands(); // Simplified below.
4327 std::swap(Op0, Op1);
4329 } else if (match(Op1I, m_Xor(m_Value(A), m_Value(B)))) {
4330 if (Op0 == A) // A^(A^B) == B
4331 return ReplaceInstUsesWith(I, B);
4332 else if (Op0 == B) // A^(B^A) == B
4333 return ReplaceInstUsesWith(I, A);
4334 } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && Op1I->hasOneUse()){
4335 if (A == Op0) { // A^(A&B) -> A^(B&A)
4336 Op1I->swapOperands();
4339 if (B == Op0) { // A^(B&A) -> (B&A)^A
4340 I.swapOperands(); // Simplified below.
4341 std::swap(Op0, Op1);
4346 BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
4349 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && Op0I->hasOneUse()) {
4350 if (A == Op1) // (B|A)^B == (A|B)^B
4352 if (B == Op1) { // (A|B)^B == A & ~B
4354 InsertNewInstBefore(BinaryOperator::createNot(Op1, "tmp"), I);
4355 return BinaryOperator::createAnd(A, NotB);
4357 } else if (match(Op0I, m_Xor(m_Value(A), m_Value(B)))) {
4358 if (Op1 == A) // (A^B)^A == B
4359 return ReplaceInstUsesWith(I, B);
4360 else if (Op1 == B) // (B^A)^A == B
4361 return ReplaceInstUsesWith(I, A);
4362 } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && Op0I->hasOneUse()){
4363 if (A == Op1) // (A&B)^A -> (B&A)^A
4365 if (B == Op1 && // (B&A)^A == ~B & A
4366 !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
4368 InsertNewInstBefore(BinaryOperator::createNot(A, "tmp"), I);
4369 return BinaryOperator::createAnd(N, Op1);
4374 // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
4375 if (Op0I && Op1I && Op0I->isShift() &&
4376 Op0I->getOpcode() == Op1I->getOpcode() &&
4377 Op0I->getOperand(1) == Op1I->getOperand(1) &&
4378 (Op1I->hasOneUse() || Op1I->hasOneUse())) {
4379 Instruction *NewOp =
4380 InsertNewInstBefore(BinaryOperator::createXor(Op0I->getOperand(0),
4381 Op1I->getOperand(0),
4382 Op0I->getName()), I);
4383 return BinaryOperator::create(Op1I->getOpcode(), NewOp,
4384 Op1I->getOperand(1));
4388 Value *A, *B, *C, *D;
4389 // (A & B)^(A | B) -> A ^ B
4390 if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
4391 match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
4392 if ((A == C && B == D) || (A == D && B == C))
4393 return BinaryOperator::createXor(A, B);
4395 // (A | B)^(A & B) -> A ^ B
4396 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
4397 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
4398 if ((A == C && B == D) || (A == D && B == C))
4399 return BinaryOperator::createXor(A, B);
4403 if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
4404 match(Op0I, m_And(m_Value(A), m_Value(B))) &&
4405 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
4406 // (X & Y)^(X & Y) -> (Y^Z) & X
4407 Value *X = 0, *Y = 0, *Z = 0;
4409 X = A, Y = B, Z = D;
4411 X = A, Y = B, Z = C;
4413 X = B, Y = A, Z = D;
4415 X = B, Y = A, Z = C;
4418 Instruction *NewOp =
4419 InsertNewInstBefore(BinaryOperator::createXor(Y, Z, Op0->getName()), I);
4420 return BinaryOperator::createAnd(NewOp, X);
4425 // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
4426 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
4427 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
4430 // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
4431 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
4432 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
4433 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
4434 const Type *SrcTy = Op0C->getOperand(0)->getType();
4435 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
4436 // Only do this if the casts both really cause code to be generated.
4437 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
4439 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
4441 Instruction *NewOp = BinaryOperator::createXor(Op0C->getOperand(0),
4442 Op1C->getOperand(0),
4444 InsertNewInstBefore(NewOp, I);
4445 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
4449 return Changed ? &I : 0;
4452 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
4453 /// overflowed for this type.
4454 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
4455 ConstantInt *In2, bool IsSigned = false) {
4456 Result = cast<ConstantInt>(Add(In1, In2));
4459 if (In2->getValue().isNegative())
4460 return Result->getValue().sgt(In1->getValue());
4462 return Result->getValue().slt(In1->getValue());
4464 return Result->getValue().ult(In1->getValue());
4467 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
4468 /// code necessary to compute the offset from the base pointer (without adding
4469 /// in the base pointer). Return the result as a signed integer of intptr size.
4470 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
4471 TargetData &TD = IC.getTargetData();
4472 gep_type_iterator GTI = gep_type_begin(GEP);
4473 const Type *IntPtrTy = TD.getIntPtrType();
4474 Value *Result = Constant::getNullValue(IntPtrTy);
4476 // Build a mask for high order bits.
4477 unsigned IntPtrWidth = TD.getPointerSize()*8;
4478 uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
4480 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
4481 Value *Op = GEP->getOperand(i);
4482 uint64_t Size = TD.getABITypeSize(GTI.getIndexedType()) & PtrSizeMask;
4483 if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
4484 if (OpC->isZero()) continue;
4486 // Handle a struct index, which adds its field offset to the pointer.
4487 if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
4488 Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
4490 if (ConstantInt *RC = dyn_cast<ConstantInt>(Result))
4491 Result = ConstantInt::get(RC->getValue() + APInt(IntPtrWidth, Size));
4493 Result = IC.InsertNewInstBefore(
4494 BinaryOperator::createAdd(Result,
4495 ConstantInt::get(IntPtrTy, Size),
4496 GEP->getName()+".offs"), I);
4500 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
4501 Constant *OC = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
4502 Scale = ConstantExpr::getMul(OC, Scale);
4503 if (Constant *RC = dyn_cast<Constant>(Result))
4504 Result = ConstantExpr::getAdd(RC, Scale);
4506 // Emit an add instruction.
4507 Result = IC.InsertNewInstBefore(
4508 BinaryOperator::createAdd(Result, Scale,
4509 GEP->getName()+".offs"), I);
4513 // Convert to correct type.
4514 if (Op->getType() != IntPtrTy) {
4515 if (Constant *OpC = dyn_cast<Constant>(Op))
4516 Op = ConstantExpr::getSExt(OpC, IntPtrTy);
4518 Op = IC.InsertNewInstBefore(new SExtInst(Op, IntPtrTy,
4519 Op->getName()+".c"), I);
4522 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
4523 if (Constant *OpC = dyn_cast<Constant>(Op))
4524 Op = ConstantExpr::getMul(OpC, Scale);
4525 else // We'll let instcombine(mul) convert this to a shl if possible.
4526 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
4527 GEP->getName()+".idx"), I);
4530 // Emit an add instruction.
4531 if (isa<Constant>(Op) && isa<Constant>(Result))
4532 Result = ConstantExpr::getAdd(cast<Constant>(Op),
4533 cast<Constant>(Result));
4535 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
4536 GEP->getName()+".offs"), I);
4541 /// FoldGEPICmp - Fold comparisons between a GEP instruction and something
4542 /// else. At this point we know that the GEP is on the LHS of the comparison.
4543 Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS,
4544 ICmpInst::Predicate Cond,
4546 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
4548 if (CastInst *CI = dyn_cast<CastInst>(RHS))
4549 if (isa<PointerType>(CI->getOperand(0)->getType()))
4550 RHS = CI->getOperand(0);
4552 Value *PtrBase = GEPLHS->getOperand(0);
4553 if (PtrBase == RHS) {
4554 // As an optimization, we don't actually have to compute the actual value of
4555 // OFFSET if this is a icmp_eq or icmp_ne comparison, just return whether
4556 // each index is zero or not.
4557 if (Cond == ICmpInst::ICMP_EQ || Cond == ICmpInst::ICMP_NE) {
4558 Instruction *InVal = 0;
4559 gep_type_iterator GTI = gep_type_begin(GEPLHS);
4560 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
4562 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
4563 if (isa<UndefValue>(C)) // undef index -> undef.
4564 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
4565 if (C->isNullValue())
4567 else if (TD->getABITypeSize(GTI.getIndexedType()) == 0) {
4568 EmitIt = false; // This is indexing into a zero sized array?
4569 } else if (isa<ConstantInt>(C))
4570 return ReplaceInstUsesWith(I, // No comparison is needed here.
4571 ConstantInt::get(Type::Int1Ty,
4572 Cond == ICmpInst::ICMP_NE));
4577 new ICmpInst(Cond, GEPLHS->getOperand(i),
4578 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
4582 InVal = InsertNewInstBefore(InVal, I);
4583 InsertNewInstBefore(Comp, I);
4584 if (Cond == ICmpInst::ICMP_NE) // True if any are unequal
4585 InVal = BinaryOperator::createOr(InVal, Comp);
4586 else // True if all are equal
4587 InVal = BinaryOperator::createAnd(InVal, Comp);
4595 // No comparison is needed here, all indexes = 0
4596 ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
4597 Cond == ICmpInst::ICMP_EQ));
4600 // Only lower this if the icmp is the only user of the GEP or if we expect
4601 // the result to fold to a constant!
4602 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
4603 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
4604 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
4605 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
4606 Constant::getNullValue(Offset->getType()));
4608 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
4609 // If the base pointers are different, but the indices are the same, just
4610 // compare the base pointer.
4611 if (PtrBase != GEPRHS->getOperand(0)) {
4612 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
4613 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
4614 GEPRHS->getOperand(0)->getType();
4616 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
4617 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
4618 IndicesTheSame = false;
4622 // If all indices are the same, just compare the base pointers.
4624 return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
4625 GEPLHS->getOperand(0), GEPRHS->getOperand(0));
4627 // Otherwise, the base pointers are different and the indices are
4628 // different, bail out.
4632 // If one of the GEPs has all zero indices, recurse.
4633 bool AllZeros = true;
4634 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
4635 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
4636 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
4641 return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
4642 ICmpInst::getSwappedPredicate(Cond), I);
4644 // If the other GEP has all zero indices, recurse.
4646 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
4647 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
4648 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
4653 return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
4655 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
4656 // If the GEPs only differ by one index, compare it.
4657 unsigned NumDifferences = 0; // Keep track of # differences.
4658 unsigned DiffOperand = 0; // The operand that differs.
4659 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
4660 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
4661 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
4662 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
4663 // Irreconcilable differences.
4667 if (NumDifferences++) break;
4672 if (NumDifferences == 0) // SAME GEP?
4673 return ReplaceInstUsesWith(I, // No comparison is needed here.
4674 ConstantInt::get(Type::Int1Ty,
4675 isTrueWhenEqual(Cond)));
4677 else if (NumDifferences == 1) {
4678 Value *LHSV = GEPLHS->getOperand(DiffOperand);
4679 Value *RHSV = GEPRHS->getOperand(DiffOperand);
4680 // Make sure we do a signed comparison here.
4681 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
4685 // Only lower this if the icmp is the only user of the GEP or if we expect
4686 // the result to fold to a constant!
4687 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
4688 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
4689 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
4690 Value *L = EmitGEPOffset(GEPLHS, I, *this);
4691 Value *R = EmitGEPOffset(GEPRHS, I, *this);
4692 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
4698 Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
4699 bool Changed = SimplifyCompare(I);
4700 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4702 // Fold trivial predicates.
4703 if (I.getPredicate() == FCmpInst::FCMP_FALSE)
4704 return ReplaceInstUsesWith(I, Constant::getNullValue(Type::Int1Ty));
4705 if (I.getPredicate() == FCmpInst::FCMP_TRUE)
4706 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
4708 // Simplify 'fcmp pred X, X'
4710 switch (I.getPredicate()) {
4711 default: assert(0 && "Unknown predicate!");
4712 case FCmpInst::FCMP_UEQ: // True if unordered or equal
4713 case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal
4714 case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal
4715 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
4716 case FCmpInst::FCMP_OGT: // True if ordered and greater than
4717 case FCmpInst::FCMP_OLT: // True if ordered and less than
4718 case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal
4719 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 0));
4721 case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
4722 case FCmpInst::FCMP_ULT: // True if unordered or less than
4723 case FCmpInst::FCMP_UGT: // True if unordered or greater than
4724 case FCmpInst::FCMP_UNE: // True if unordered or not equal
4725 // Canonicalize these to be 'fcmp uno %X, 0.0'.
4726 I.setPredicate(FCmpInst::FCMP_UNO);
4727 I.setOperand(1, Constant::getNullValue(Op0->getType()));
4730 case FCmpInst::FCMP_ORD: // True if ordered (no nans)
4731 case FCmpInst::FCMP_OEQ: // True if ordered and equal
4732 case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
4733 case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
4734 // Canonicalize these to be 'fcmp ord %X, 0.0'.
4735 I.setPredicate(FCmpInst::FCMP_ORD);
4736 I.setOperand(1, Constant::getNullValue(Op0->getType()));
4741 if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef
4742 return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
4744 // Handle fcmp with constant RHS
4745 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
4746 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
4747 switch (LHSI->getOpcode()) {
4748 case Instruction::PHI:
4749 if (Instruction *NV = FoldOpIntoPhi(I))
4752 case Instruction::Select:
4753 // If either operand of the select is a constant, we can fold the
4754 // comparison into the select arms, which will cause one to be
4755 // constant folded and the select turned into a bitwise or.
4756 Value *Op1 = 0, *Op2 = 0;
4757 if (LHSI->hasOneUse()) {
4758 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
4759 // Fold the known value into the constant operand.
4760 Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
4761 // Insert a new FCmp of the other select operand.
4762 Op2 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
4763 LHSI->getOperand(2), RHSC,
4765 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
4766 // Fold the known value into the constant operand.
4767 Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
4768 // Insert a new FCmp of the other select operand.
4769 Op1 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
4770 LHSI->getOperand(1), RHSC,
4776 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
4781 return Changed ? &I : 0;
4784 Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
4785 bool Changed = SimplifyCompare(I);
4786 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4787 const Type *Ty = Op0->getType();
4791 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
4792 isTrueWhenEqual(I)));
4794 if (isa<UndefValue>(Op1)) // X icmp undef -> undef
4795 return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
4797 // (icmp cond (sub m A) 0) ->
4800 ConstantInt *C1, *C2;
4802 // Check both arguments of the compare for a matching subtract.
4803 if (match(Op0, m_ConstantInt(C1)) && C1->getValue() == 0 &&
4804 match(Op1, m_Sub(m_ConstantInt(C2), m_Value(A)))) {
4805 // We managed to fold the add into the RHS of the select condition.
4806 return new ICmpInst(I.getPredicate(), A, C2);
4807 } else if (match(Op1, m_ConstantInt(C1)) && C1->getValue() == 0 &&
4808 match(Op0, m_Sub(m_ConstantInt(C2), m_Value(A)))) {
4809 // We managed to fold the add into the LHS of the select condition.
4810 return new ICmpInst(I.getPredicate(), C2, A);
4814 // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
4815 // addresses never equal each other! We already know that Op0 != Op1.
4816 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
4817 isa<ConstantPointerNull>(Op0)) &&
4818 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
4819 isa<ConstantPointerNull>(Op1)))
4820 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
4821 !isTrueWhenEqual(I)));
4823 // icmp's with boolean values can always be turned into bitwise operations
4824 if (Ty == Type::Int1Ty) {
4825 switch (I.getPredicate()) {
4826 default: assert(0 && "Invalid icmp instruction!");
4827 case ICmpInst::ICMP_EQ: { // icmp eq bool %A, %B -> ~(A^B)
4828 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
4829 InsertNewInstBefore(Xor, I);
4830 return BinaryOperator::createNot(Xor);
4832 case ICmpInst::ICMP_NE: // icmp eq bool %A, %B -> A^B
4833 return BinaryOperator::createXor(Op0, Op1);
4835 case ICmpInst::ICMP_UGT:
4836 case ICmpInst::ICMP_SGT:
4837 std::swap(Op0, Op1); // Change icmp gt -> icmp lt
4839 case ICmpInst::ICMP_ULT:
4840 case ICmpInst::ICMP_SLT: { // icmp lt bool A, B -> ~X & Y
4841 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
4842 InsertNewInstBefore(Not, I);
4843 return BinaryOperator::createAnd(Not, Op1);
4845 case ICmpInst::ICMP_UGE:
4846 case ICmpInst::ICMP_SGE:
4847 std::swap(Op0, Op1); // Change icmp ge -> icmp le
4849 case ICmpInst::ICMP_ULE:
4850 case ICmpInst::ICMP_SLE: { // icmp le bool %A, %B -> ~A | B
4851 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
4852 InsertNewInstBefore(Not, I);
4853 return BinaryOperator::createOr(Not, Op1);
4858 // See if we are doing a comparison between a constant and an instruction that
4859 // can be folded into the comparison.
4860 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
4861 switch (I.getPredicate()) {
4863 case ICmpInst::ICMP_ULT: // A <u MIN -> FALSE
4864 if (CI->isMinValue(false))
4865 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4866 if (CI->isMaxValue(false)) // A <u MAX -> A != MAX
4867 return new ICmpInst(ICmpInst::ICMP_NE, Op0,Op1);
4868 if (isMinValuePlusOne(CI,false)) // A <u MIN+1 -> A == MIN
4869 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
4870 // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
4871 if (CI->isMinValue(true))
4872 return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
4873 ConstantInt::getAllOnesValue(Op0->getType()));
4877 case ICmpInst::ICMP_SLT:
4878 if (CI->isMinValue(true)) // A <s MIN -> FALSE
4879 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4880 if (CI->isMaxValue(true)) // A <s MAX -> A != MAX
4881 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4882 if (isMinValuePlusOne(CI,true)) // A <s MIN+1 -> A == MIN
4883 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
4886 case ICmpInst::ICMP_UGT:
4887 if (CI->isMaxValue(false)) // A >u MAX -> FALSE
4888 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4889 if (CI->isMinValue(false)) // A >u MIN -> A != MIN
4890 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4891 if (isMaxValueMinusOne(CI, false)) // A >u MAX-1 -> A == MAX
4892 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
4894 // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
4895 if (CI->isMaxValue(true))
4896 return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
4897 ConstantInt::getNullValue(Op0->getType()));
4900 case ICmpInst::ICMP_SGT:
4901 if (CI->isMaxValue(true)) // A >s MAX -> FALSE
4902 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4903 if (CI->isMinValue(true)) // A >s MIN -> A != MIN
4904 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4905 if (isMaxValueMinusOne(CI, true)) // A >s MAX-1 -> A == MAX
4906 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
4909 case ICmpInst::ICMP_ULE:
4910 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
4911 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4912 if (CI->isMinValue(false)) // A <=u MIN -> A == MIN
4913 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
4914 if (isMaxValueMinusOne(CI,false)) // A <=u MAX-1 -> A != MAX
4915 return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
4918 case ICmpInst::ICMP_SLE:
4919 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
4920 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4921 if (CI->isMinValue(true)) // A <=s MIN -> A == MIN
4922 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
4923 if (isMaxValueMinusOne(CI,true)) // A <=s MAX-1 -> A != MAX
4924 return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
4927 case ICmpInst::ICMP_UGE:
4928 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
4929 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4930 if (CI->isMaxValue(false)) // A >=u MAX -> A == MAX
4931 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
4932 if (isMinValuePlusOne(CI,false)) // A >=u MIN-1 -> A != MIN
4933 return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
4936 case ICmpInst::ICMP_SGE:
4937 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
4938 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4939 if (CI->isMaxValue(true)) // A >=s MAX -> A == MAX
4940 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
4941 if (isMinValuePlusOne(CI,true)) // A >=s MIN-1 -> A != MIN
4942 return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
4946 // If we still have a icmp le or icmp ge instruction, turn it into the
4947 // appropriate icmp lt or icmp gt instruction. Since the border cases have
4948 // already been handled above, this requires little checking.
4950 switch (I.getPredicate()) {
4952 case ICmpInst::ICMP_ULE:
4953 return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
4954 case ICmpInst::ICMP_SLE:
4955 return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
4956 case ICmpInst::ICMP_UGE:
4957 return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
4958 case ICmpInst::ICMP_SGE:
4959 return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
4962 // See if we can fold the comparison based on bits known to be zero or one
4963 // in the input. If this comparison is a normal comparison, it demands all
4964 // bits, if it is a sign bit comparison, it only demands the sign bit.
4967 bool isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
4969 uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
4970 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
4971 if (SimplifyDemandedBits(Op0,
4972 isSignBit ? APInt::getSignBit(BitWidth)
4973 : APInt::getAllOnesValue(BitWidth),
4974 KnownZero, KnownOne, 0))
4977 // Given the known and unknown bits, compute a range that the LHS could be
4979 if ((KnownOne | KnownZero) != 0) {
4980 // Compute the Min, Max and RHS values based on the known bits. For the
4981 // EQ and NE we use unsigned values.
4982 APInt Min(BitWidth, 0), Max(BitWidth, 0);
4983 const APInt& RHSVal = CI->getValue();
4984 if (ICmpInst::isSignedPredicate(I.getPredicate())) {
4985 ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min,
4988 ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min,
4991 switch (I.getPredicate()) { // LE/GE have been folded already.
4992 default: assert(0 && "Unknown icmp opcode!");
4993 case ICmpInst::ICMP_EQ:
4994 if (Max.ult(RHSVal) || Min.ugt(RHSVal))
4995 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4997 case ICmpInst::ICMP_NE:
4998 if (Max.ult(RHSVal) || Min.ugt(RHSVal))
4999 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
5001 case ICmpInst::ICMP_ULT:
5002 if (Max.ult(RHSVal))
5003 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
5004 if (Min.uge(RHSVal))
5005 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
5007 case ICmpInst::ICMP_UGT:
5008 if (Min.ugt(RHSVal))
5009 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
5010 if (Max.ule(RHSVal))
5011 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
5013 case ICmpInst::ICMP_SLT:
5014 if (Max.slt(RHSVal))
5015 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
5016 if (Min.sgt(RHSVal))
5017 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
5019 case ICmpInst::ICMP_SGT:
5020 if (Min.sgt(RHSVal))
5021 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
5022 if (Max.sle(RHSVal))
5023 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
5028 // Since the RHS is a ConstantInt (CI), if the left hand side is an
5029 // instruction, see if that instruction also has constants so that the
5030 // instruction can be folded into the icmp
5031 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
5032 if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
5036 // Handle icmp with constant (but not simple integer constant) RHS
5037 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
5038 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
5039 switch (LHSI->getOpcode()) {
5040 case Instruction::GetElementPtr:
5041 if (RHSC->isNullValue()) {
5042 // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
5043 bool isAllZeros = true;
5044 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
5045 if (!isa<Constant>(LHSI->getOperand(i)) ||
5046 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
5051 return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
5052 Constant::getNullValue(LHSI->getOperand(0)->getType()));
5056 case Instruction::PHI:
5057 if (Instruction *NV = FoldOpIntoPhi(I))
5060 case Instruction::Select: {
5061 // If either operand of the select is a constant, we can fold the
5062 // comparison into the select arms, which will cause one to be
5063 // constant folded and the select turned into a bitwise or.
5064 Value *Op1 = 0, *Op2 = 0;
5065 if (LHSI->hasOneUse()) {
5066 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
5067 // Fold the known value into the constant operand.
5068 Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
5069 // Insert a new ICmp of the other select operand.
5070 Op2 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
5071 LHSI->getOperand(2), RHSC,
5073 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
5074 // Fold the known value into the constant operand.
5075 Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
5076 // Insert a new ICmp of the other select operand.
5077 Op1 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
5078 LHSI->getOperand(1), RHSC,
5084 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
5087 case Instruction::Malloc:
5088 // If we have (malloc != null), and if the malloc has a single use, we
5089 // can assume it is successful and remove the malloc.
5090 if (LHSI->hasOneUse() && isa<ConstantPointerNull>(RHSC)) {
5091 AddToWorkList(LHSI);
5092 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
5093 !isTrueWhenEqual(I)));
5099 // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
5100 if (User *GEP = dyn_castGetElementPtr(Op0))
5101 if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
5103 if (User *GEP = dyn_castGetElementPtr(Op1))
5104 if (Instruction *NI = FoldGEPICmp(GEP, Op0,
5105 ICmpInst::getSwappedPredicate(I.getPredicate()), I))
5108 // Test to see if the operands of the icmp are casted versions of other
5109 // values. If the ptr->ptr cast can be stripped off both arguments, we do so
5111 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
5112 if (isa<PointerType>(Op0->getType()) &&
5113 (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
5114 // We keep moving the cast from the left operand over to the right
5115 // operand, where it can often be eliminated completely.
5116 Op0 = CI->getOperand(0);
5118 // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
5119 // so eliminate it as well.
5120 if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
5121 Op1 = CI2->getOperand(0);
5123 // If Op1 is a constant, we can fold the cast into the constant.
5124 if (Op0->getType() != Op1->getType())
5125 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
5126 Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
5128 // Otherwise, cast the RHS right before the icmp
5129 Op1 = InsertCastBefore(Instruction::BitCast, Op1, Op0->getType(), I);
5131 return new ICmpInst(I.getPredicate(), Op0, Op1);
5135 if (isa<CastInst>(Op0)) {
5136 // Handle the special case of: icmp (cast bool to X), <cst>
5137 // This comes up when you have code like
5140 // For generality, we handle any zero-extension of any operand comparison
5141 // with a constant or another cast from the same type.
5142 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
5143 if (Instruction *R = visitICmpInstWithCastAndCast(I))
5147 if (I.isEquality()) {
5148 Value *A, *B, *C, *D;
5149 if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
5150 if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
5151 Value *OtherVal = A == Op1 ? B : A;
5152 return new ICmpInst(I.getPredicate(), OtherVal,
5153 Constant::getNullValue(A->getType()));
5156 if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
5157 // A^c1 == C^c2 --> A == C^(c1^c2)
5158 if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
5159 if (ConstantInt *C2 = dyn_cast<ConstantInt>(D))
5160 if (Op1->hasOneUse()) {
5161 Constant *NC = ConstantInt::get(C1->getValue() ^ C2->getValue());
5162 Instruction *Xor = BinaryOperator::createXor(C, NC, "tmp");
5163 return new ICmpInst(I.getPredicate(), A,
5164 InsertNewInstBefore(Xor, I));
5167 // A^B == A^D -> B == D
5168 if (A == C) return new ICmpInst(I.getPredicate(), B, D);
5169 if (A == D) return new ICmpInst(I.getPredicate(), B, C);
5170 if (B == C) return new ICmpInst(I.getPredicate(), A, D);
5171 if (B == D) return new ICmpInst(I.getPredicate(), A, C);
5175 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
5176 (A == Op0 || B == Op0)) {
5177 // A == (A^B) -> B == 0
5178 Value *OtherVal = A == Op0 ? B : A;
5179 return new ICmpInst(I.getPredicate(), OtherVal,
5180 Constant::getNullValue(A->getType()));
5182 if (match(Op0, m_Sub(m_Value(A), m_Value(B))) && A == Op1) {
5183 // (A-B) == A -> B == 0
5184 return new ICmpInst(I.getPredicate(), B,
5185 Constant::getNullValue(B->getType()));
5187 if (match(Op1, m_Sub(m_Value(A), m_Value(B))) && A == Op0) {
5188 // A == (A-B) -> B == 0
5189 return new ICmpInst(I.getPredicate(), B,
5190 Constant::getNullValue(B->getType()));
5193 // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
5194 if (Op0->hasOneUse() && Op1->hasOneUse() &&
5195 match(Op0, m_And(m_Value(A), m_Value(B))) &&
5196 match(Op1, m_And(m_Value(C), m_Value(D)))) {
5197 Value *X = 0, *Y = 0, *Z = 0;
5200 X = B; Y = D; Z = A;
5201 } else if (A == D) {
5202 X = B; Y = C; Z = A;
5203 } else if (B == C) {
5204 X = A; Y = D; Z = B;
5205 } else if (B == D) {
5206 X = A; Y = C; Z = B;
5209 if (X) { // Build (X^Y) & Z
5210 Op1 = InsertNewInstBefore(BinaryOperator::createXor(X, Y, "tmp"), I);
5211 Op1 = InsertNewInstBefore(BinaryOperator::createAnd(Op1, Z, "tmp"), I);
5212 I.setOperand(0, Op1);
5213 I.setOperand(1, Constant::getNullValue(Op1->getType()));
5218 return Changed ? &I : 0;
5222 /// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
5223 /// and CmpRHS are both known to be integer constants.
5224 Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
5225 ConstantInt *DivRHS) {
5226 ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
5227 const APInt &CmpRHSV = CmpRHS->getValue();
5229 // FIXME: If the operand types don't match the type of the divide
5230 // then don't attempt this transform. The code below doesn't have the
5231 // logic to deal with a signed divide and an unsigned compare (and
5232 // vice versa). This is because (x /s C1) <s C2 produces different
5233 // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
5234 // (x /u C1) <u C2. Simply casting the operands and result won't
5235 // work. :( The if statement below tests that condition and bails
5237 bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
5238 if (!ICI.isEquality() && DivIsSigned != ICI.isSignedPredicate())
5240 if (DivRHS->isZero())
5241 return 0; // The ProdOV computation fails on divide by zero.
5243 // Compute Prod = CI * DivRHS. We are essentially solving an equation
5244 // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
5245 // C2 (CI). By solving for X we can turn this into a range check
5246 // instead of computing a divide.
5247 ConstantInt *Prod = Multiply(CmpRHS, DivRHS);
5249 // Determine if the product overflows by seeing if the product is
5250 // not equal to the divide. Make sure we do the same kind of divide
5251 // as in the LHS instruction that we're folding.
5252 bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
5253 ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
5255 // Get the ICmp opcode
5256 ICmpInst::Predicate Pred = ICI.getPredicate();
5258 // Figure out the interval that is being checked. For example, a comparison
5259 // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
5260 // Compute this interval based on the constants involved and the signedness of
5261 // the compare/divide. This computes a half-open interval, keeping track of
5262 // whether either value in the interval overflows. After analysis each
5263 // overflow variable is set to 0 if it's corresponding bound variable is valid
5264 // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
5265 int LoOverflow = 0, HiOverflow = 0;
5266 ConstantInt *LoBound = 0, *HiBound = 0;
5269 if (!DivIsSigned) { // udiv
5270 // e.g. X/5 op 3 --> [15, 20)
5272 HiOverflow = LoOverflow = ProdOV;
5274 HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false);
5275 } else if (DivRHS->getValue().isPositive()) { // Divisor is > 0.
5276 if (CmpRHSV == 0) { // (X / pos) op 0
5277 // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
5278 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
5280 } else if (CmpRHSV.isPositive()) { // (X / pos) op pos
5281 LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
5282 HiOverflow = LoOverflow = ProdOV;
5284 HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true);
5285 } else { // (X / pos) op neg
5286 // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
5287 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
5288 LoOverflow = AddWithOverflow(LoBound, Prod,
5289 cast<ConstantInt>(DivRHSH), true) ? -1 : 0;
5290 HiBound = AddOne(Prod);
5291 HiOverflow = ProdOV ? -1 : 0;
5293 } else { // Divisor is < 0.
5294 if (CmpRHSV == 0) { // (X / neg) op 0
5295 // e.g. X/-5 op 0 --> [-4, 5)
5296 LoBound = AddOne(DivRHS);
5297 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
5298 if (HiBound == DivRHS) { // -INTMIN = INTMIN
5299 HiOverflow = 1; // [INTMIN+1, overflow)
5300 HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
5302 } else if (CmpRHSV.isPositive()) { // (X / neg) op pos
5303 // e.g. X/-5 op 3 --> [-19, -14)
5304 HiOverflow = LoOverflow = ProdOV ? -1 : 0;
5306 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS), true) ?-1:0;
5307 HiBound = AddOne(Prod);
5308 } else { // (X / neg) op neg
5309 // e.g. X/-5 op -3 --> [15, 20)
5311 LoOverflow = HiOverflow = ProdOV ? 1 : 0;
5312 HiBound = Subtract(Prod, DivRHS);
5315 // Dividing by a negative swaps the condition. LT <-> GT
5316 Pred = ICmpInst::getSwappedPredicate(Pred);
5319 Value *X = DivI->getOperand(0);
5321 default: assert(0 && "Unhandled icmp opcode!");
5322 case ICmpInst::ICMP_EQ:
5323 if (LoOverflow && HiOverflow)
5324 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5325 else if (HiOverflow)
5326 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
5327 ICmpInst::ICMP_UGE, X, LoBound);
5328 else if (LoOverflow)
5329 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
5330 ICmpInst::ICMP_ULT, X, HiBound);
5332 return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
5333 case ICmpInst::ICMP_NE:
5334 if (LoOverflow && HiOverflow)
5335 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5336 else if (HiOverflow)
5337 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
5338 ICmpInst::ICMP_ULT, X, LoBound);
5339 else if (LoOverflow)
5340 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
5341 ICmpInst::ICMP_UGE, X, HiBound);
5343 return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
5344 case ICmpInst::ICMP_ULT:
5345 case ICmpInst::ICMP_SLT:
5346 if (LoOverflow == +1) // Low bound is greater than input range.
5347 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5348 if (LoOverflow == -1) // Low bound is less than input range.
5349 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5350 return new ICmpInst(Pred, X, LoBound);
5351 case ICmpInst::ICMP_UGT:
5352 case ICmpInst::ICMP_SGT:
5353 if (HiOverflow == +1) // High bound greater than input range.
5354 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5355 else if (HiOverflow == -1) // High bound less than input range.
5356 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5357 if (Pred == ICmpInst::ICMP_UGT)
5358 return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
5360 return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
5365 /// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
5367 Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
5370 const APInt &RHSV = RHS->getValue();
5372 switch (LHSI->getOpcode()) {
5373 case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
5374 if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
5375 // If this is a comparison that tests the signbit (X < 0) or (x > -1),
5377 if (ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0 ||
5378 ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue()) {
5379 Value *CompareVal = LHSI->getOperand(0);
5381 // If the sign bit of the XorCST is not set, there is no change to
5382 // the operation, just stop using the Xor.
5383 if (!XorCST->getValue().isNegative()) {
5384 ICI.setOperand(0, CompareVal);
5385 AddToWorkList(LHSI);
5389 // Was the old condition true if the operand is positive?
5390 bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
5392 // If so, the new one isn't.
5393 isTrueIfPositive ^= true;
5395 if (isTrueIfPositive)
5396 return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, SubOne(RHS));
5398 return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, AddOne(RHS));
5402 case Instruction::And: // (icmp pred (and X, AndCST), RHS)
5403 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
5404 LHSI->getOperand(0)->hasOneUse()) {
5405 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
5407 // If the LHS is an AND of a truncating cast, we can widen the
5408 // and/compare to be the input width without changing the value
5409 // produced, eliminating a cast.
5410 if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
5411 // We can do this transformation if either the AND constant does not
5412 // have its sign bit set or if it is an equality comparison.
5413 // Extending a relational comparison when we're checking the sign
5414 // bit would not work.
5415 if (Cast->hasOneUse() &&
5416 (ICI.isEquality() || AndCST->getValue().isPositive() &&
5417 RHSV.isPositive())) {
5419 cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
5420 APInt NewCST = AndCST->getValue();
5421 NewCST.zext(BitWidth);
5423 NewCI.zext(BitWidth);
5424 Instruction *NewAnd =
5425 BinaryOperator::createAnd(Cast->getOperand(0),
5426 ConstantInt::get(NewCST),LHSI->getName());
5427 InsertNewInstBefore(NewAnd, ICI);
5428 return new ICmpInst(ICI.getPredicate(), NewAnd,
5429 ConstantInt::get(NewCI));
5433 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
5434 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
5435 // happens a LOT in code produced by the C front-end, for bitfield
5437 BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
5438 if (Shift && !Shift->isShift())
5442 ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
5443 const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
5444 const Type *AndTy = AndCST->getType(); // Type of the and.
5446 // We can fold this as long as we can't shift unknown bits
5447 // into the mask. This can only happen with signed shift
5448 // rights, as they sign-extend.
5450 bool CanFold = Shift->isLogicalShift();
5452 // To test for the bad case of the signed shr, see if any
5453 // of the bits shifted in could be tested after the mask.
5454 uint32_t TyBits = Ty->getPrimitiveSizeInBits();
5455 int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
5457 uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
5458 if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
5459 AndCST->getValue()) == 0)
5465 if (Shift->getOpcode() == Instruction::Shl)
5466 NewCst = ConstantExpr::getLShr(RHS, ShAmt);
5468 NewCst = ConstantExpr::getShl(RHS, ShAmt);
5470 // Check to see if we are shifting out any of the bits being
5472 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != RHS) {
5473 // If we shifted bits out, the fold is not going to work out.
5474 // As a special case, check to see if this means that the
5475 // result is always true or false now.
5476 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
5477 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5478 if (ICI.getPredicate() == ICmpInst::ICMP_NE)
5479 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5481 ICI.setOperand(1, NewCst);
5482 Constant *NewAndCST;
5483 if (Shift->getOpcode() == Instruction::Shl)
5484 NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
5486 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
5487 LHSI->setOperand(1, NewAndCST);
5488 LHSI->setOperand(0, Shift->getOperand(0));
5489 AddToWorkList(Shift); // Shift is dead.
5490 AddUsesToWorkList(ICI);
5496 // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
5497 // preferable because it allows the C<<Y expression to be hoisted out
5498 // of a loop if Y is invariant and X is not.
5499 if (Shift && Shift->hasOneUse() && RHSV == 0 &&
5500 ICI.isEquality() && !Shift->isArithmeticShift() &&
5501 isa<Instruction>(Shift->getOperand(0))) {
5504 if (Shift->getOpcode() == Instruction::LShr) {
5505 NS = BinaryOperator::createShl(AndCST,
5506 Shift->getOperand(1), "tmp");
5508 // Insert a logical shift.
5509 NS = BinaryOperator::createLShr(AndCST,
5510 Shift->getOperand(1), "tmp");
5512 InsertNewInstBefore(cast<Instruction>(NS), ICI);
5514 // Compute X & (C << Y).
5515 Instruction *NewAnd =
5516 BinaryOperator::createAnd(Shift->getOperand(0), NS, LHSI->getName());
5517 InsertNewInstBefore(NewAnd, ICI);
5519 ICI.setOperand(0, NewAnd);
5525 case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
5526 ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
5529 uint32_t TypeBits = RHSV.getBitWidth();
5531 // Check that the shift amount is in range. If not, don't perform
5532 // undefined shifts. When the shift is visited it will be
5534 if (ShAmt->uge(TypeBits))
5537 if (ICI.isEquality()) {
5538 // If we are comparing against bits always shifted out, the
5539 // comparison cannot succeed.
5541 ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), ShAmt);
5542 if (Comp != RHS) {// Comparing against a bit that we know is zero.
5543 bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
5544 Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
5545 return ReplaceInstUsesWith(ICI, Cst);
5548 if (LHSI->hasOneUse()) {
5549 // Otherwise strength reduce the shift into an and.
5550 uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
5552 ConstantInt::get(APInt::getLowBitsSet(TypeBits, TypeBits-ShAmtVal));
5555 BinaryOperator::createAnd(LHSI->getOperand(0),
5556 Mask, LHSI->getName()+".mask");
5557 Value *And = InsertNewInstBefore(AndI, ICI);
5558 return new ICmpInst(ICI.getPredicate(), And,
5559 ConstantInt::get(RHSV.lshr(ShAmtVal)));
5563 // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
5564 bool TrueIfSigned = false;
5565 if (LHSI->hasOneUse() &&
5566 isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
5567 // (X << 31) <s 0 --> (X&1) != 0
5568 Constant *Mask = ConstantInt::get(APInt(TypeBits, 1) <<
5569 (TypeBits-ShAmt->getZExtValue()-1));
5571 BinaryOperator::createAnd(LHSI->getOperand(0),
5572 Mask, LHSI->getName()+".mask");
5573 Value *And = InsertNewInstBefore(AndI, ICI);
5575 return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
5576 And, Constant::getNullValue(And->getType()));
5581 case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
5582 case Instruction::AShr: {
5583 ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
5586 if (ICI.isEquality()) {
5587 // Check that the shift amount is in range. If not, don't perform
5588 // undefined shifts. When the shift is visited it will be
5590 uint32_t TypeBits = RHSV.getBitWidth();
5591 if (ShAmt->uge(TypeBits))
5593 uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
5595 // If we are comparing against bits always shifted out, the
5596 // comparison cannot succeed.
5597 APInt Comp = RHSV << ShAmtVal;
5598 if (LHSI->getOpcode() == Instruction::LShr)
5599 Comp = Comp.lshr(ShAmtVal);
5601 Comp = Comp.ashr(ShAmtVal);
5603 if (Comp != RHSV) { // Comparing against a bit that we know is zero.
5604 bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
5605 Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
5606 return ReplaceInstUsesWith(ICI, Cst);
5609 if (LHSI->hasOneUse() || RHSV == 0) {
5610 // Otherwise strength reduce the shift into an and.
5611 APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
5612 Constant *Mask = ConstantInt::get(Val);
5615 BinaryOperator::createAnd(LHSI->getOperand(0),
5616 Mask, LHSI->getName()+".mask");
5617 Value *And = InsertNewInstBefore(AndI, ICI);
5618 return new ICmpInst(ICI.getPredicate(), And,
5619 ConstantExpr::getShl(RHS, ShAmt));
5625 case Instruction::SDiv:
5626 case Instruction::UDiv:
5627 // Fold: icmp pred ([us]div X, C1), C2 -> range test
5628 // Fold this div into the comparison, producing a range check.
5629 // Determine, based on the divide type, what the range is being
5630 // checked. If there is an overflow on the low or high side, remember
5631 // it, otherwise compute the range [low, hi) bounding the new value.
5632 // See: InsertRangeTest above for the kinds of replacements possible.
5633 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
5634 if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
5640 // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
5641 if (ICI.isEquality()) {
5642 bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
5644 // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
5645 // the second operand is a constant, simplify a bit.
5646 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
5647 switch (BO->getOpcode()) {
5648 case Instruction::SRem:
5649 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
5650 if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
5651 const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
5652 if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
5653 Instruction *NewRem =
5654 BinaryOperator::createURem(BO->getOperand(0), BO->getOperand(1),
5656 InsertNewInstBefore(NewRem, ICI);
5657 return new ICmpInst(ICI.getPredicate(), NewRem,
5658 Constant::getNullValue(BO->getType()));
5662 case Instruction::Add:
5663 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
5664 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
5665 if (BO->hasOneUse())
5666 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
5667 Subtract(RHS, BOp1C));
5668 } else if (RHSV == 0) {
5669 // Replace ((add A, B) != 0) with (A != -B) if A or B is
5670 // efficiently invertible, or if the add has just this one use.
5671 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
5673 if (Value *NegVal = dyn_castNegVal(BOp1))
5674 return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
5675 else if (Value *NegVal = dyn_castNegVal(BOp0))
5676 return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
5677 else if (BO->hasOneUse()) {
5678 Instruction *Neg = BinaryOperator::createNeg(BOp1);
5679 InsertNewInstBefore(Neg, ICI);
5681 return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
5685 case Instruction::Xor:
5686 // For the xor case, we can xor two constants together, eliminating
5687 // the explicit xor.
5688 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
5689 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
5690 ConstantExpr::getXor(RHS, BOC));
5693 case Instruction::Sub:
5694 // Replace (([sub|xor] A, B) != 0) with (A != B)
5696 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
5700 case Instruction::Or:
5701 // If bits are being or'd in that are not present in the constant we
5702 // are comparing against, then the comparison could never succeed!
5703 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
5704 Constant *NotCI = ConstantExpr::getNot(RHS);
5705 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
5706 return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
5711 case Instruction::And:
5712 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
5713 // If bits are being compared against that are and'd out, then the
5714 // comparison can never succeed!
5715 if ((RHSV & ~BOC->getValue()) != 0)
5716 return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
5719 // If we have ((X & C) == C), turn it into ((X & C) != 0).
5720 if (RHS == BOC && RHSV.isPowerOf2())
5721 return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
5722 ICmpInst::ICMP_NE, LHSI,
5723 Constant::getNullValue(RHS->getType()));
5725 // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
5726 if (isSignBit(BOC)) {
5727 Value *X = BO->getOperand(0);
5728 Constant *Zero = Constant::getNullValue(X->getType());
5729 ICmpInst::Predicate pred = isICMP_NE ?
5730 ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
5731 return new ICmpInst(pred, X, Zero);
5734 // ((X & ~7) == 0) --> X < 8
5735 if (RHSV == 0 && isHighOnes(BOC)) {
5736 Value *X = BO->getOperand(0);
5737 Constant *NegX = ConstantExpr::getNeg(BOC);
5738 ICmpInst::Predicate pred = isICMP_NE ?
5739 ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
5740 return new ICmpInst(pred, X, NegX);
5745 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
5746 // Handle icmp {eq|ne} <intrinsic>, intcst.
5747 if (II->getIntrinsicID() == Intrinsic::bswap) {
5749 ICI.setOperand(0, II->getOperand(1));
5750 ICI.setOperand(1, ConstantInt::get(RHSV.byteSwap()));
5754 } else { // Not a ICMP_EQ/ICMP_NE
5755 // If the LHS is a cast from an integral value of the same size,
5756 // then since we know the RHS is a constant, try to simlify.
5757 if (CastInst *Cast = dyn_cast<CastInst>(LHSI)) {
5758 Value *CastOp = Cast->getOperand(0);
5759 const Type *SrcTy = CastOp->getType();
5760 uint32_t SrcTySize = SrcTy->getPrimitiveSizeInBits();
5761 if (SrcTy->isInteger() &&
5762 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
5763 // If this is an unsigned comparison, try to make the comparison use
5764 // smaller constant values.
5765 if (ICI.getPredicate() == ICmpInst::ICMP_ULT && RHSV.isSignBit()) {
5766 // X u< 128 => X s> -1
5767 return new ICmpInst(ICmpInst::ICMP_SGT, CastOp,
5768 ConstantInt::get(APInt::getAllOnesValue(SrcTySize)));
5769 } else if (ICI.getPredicate() == ICmpInst::ICMP_UGT &&
5770 RHSV == APInt::getSignedMaxValue(SrcTySize)) {
5771 // X u> 127 => X s< 0
5772 return new ICmpInst(ICmpInst::ICMP_SLT, CastOp,
5773 Constant::getNullValue(SrcTy));
5781 /// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
5782 /// We only handle extending casts so far.
5784 Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
5785 const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
5786 Value *LHSCIOp = LHSCI->getOperand(0);
5787 const Type *SrcTy = LHSCIOp->getType();
5788 const Type *DestTy = LHSCI->getType();
5791 // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
5792 // integer type is the same size as the pointer type.
5793 if (LHSCI->getOpcode() == Instruction::PtrToInt &&
5794 getTargetData().getPointerSizeInBits() ==
5795 cast<IntegerType>(DestTy)->getBitWidth()) {
5797 if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
5798 RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
5799 } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
5800 RHSOp = RHSC->getOperand(0);
5801 // If the pointer types don't match, insert a bitcast.
5802 if (LHSCIOp->getType() != RHSOp->getType())
5803 RHSOp = InsertCastBefore(Instruction::BitCast, RHSOp,
5804 LHSCIOp->getType(), ICI);
5808 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
5811 // The code below only handles extension cast instructions, so far.
5813 if (LHSCI->getOpcode() != Instruction::ZExt &&
5814 LHSCI->getOpcode() != Instruction::SExt)
5817 bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
5818 bool isSignedCmp = ICI.isSignedPredicate();
5820 if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
5821 // Not an extension from the same type?
5822 RHSCIOp = CI->getOperand(0);
5823 if (RHSCIOp->getType() != LHSCIOp->getType())
5826 // If the signedness of the two compares doesn't agree (i.e. one is a sext
5827 // and the other is a zext), then we can't handle this.
5828 if (CI->getOpcode() != LHSCI->getOpcode())
5831 // Likewise, if the signedness of the [sz]exts and the compare don't match,
5832 // then we can't handle this.
5833 if (isSignedExt != isSignedCmp && !ICI.isEquality())
5836 // Okay, just insert a compare of the reduced operands now!
5837 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
5840 // If we aren't dealing with a constant on the RHS, exit early
5841 ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
5845 // Compute the constant that would happen if we truncated to SrcTy then
5846 // reextended to DestTy.
5847 Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
5848 Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
5850 // If the re-extended constant didn't change...
5852 // Make sure that sign of the Cmp and the sign of the Cast are the same.
5853 // For example, we might have:
5854 // %A = sext short %X to uint
5855 // %B = icmp ugt uint %A, 1330
5856 // It is incorrect to transform this into
5857 // %B = icmp ugt short %X, 1330
5858 // because %A may have negative value.
5860 // However, it is OK if SrcTy is bool (See cast-set.ll testcase)
5861 // OR operation is EQ/NE.
5862 if (isSignedExt == isSignedCmp || SrcTy == Type::Int1Ty || ICI.isEquality())
5863 return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
5868 // The re-extended constant changed so the constant cannot be represented
5869 // in the shorter type. Consequently, we cannot emit a simple comparison.
5871 // First, handle some easy cases. We know the result cannot be equal at this
5872 // point so handle the ICI.isEquality() cases
5873 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
5874 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5875 if (ICI.getPredicate() == ICmpInst::ICMP_NE)
5876 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5878 // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
5879 // should have been folded away previously and not enter in here.
5882 // We're performing a signed comparison.
5883 if (cast<ConstantInt>(CI)->getValue().isNegative())
5884 Result = ConstantInt::getFalse(); // X < (small) --> false
5886 Result = ConstantInt::getTrue(); // X < (large) --> true
5888 // We're performing an unsigned comparison.
5890 // We're performing an unsigned comp with a sign extended value.
5891 // This is true if the input is >= 0. [aka >s -1]
5892 Constant *NegOne = ConstantInt::getAllOnesValue(SrcTy);
5893 Result = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_SGT, LHSCIOp,
5894 NegOne, ICI.getName()), ICI);
5896 // Unsigned extend & unsigned compare -> always true.
5897 Result = ConstantInt::getTrue();
5901 // Finally, return the value computed.
5902 if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
5903 ICI.getPredicate() == ICmpInst::ICMP_SLT) {
5904 return ReplaceInstUsesWith(ICI, Result);
5906 assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
5907 ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
5908 "ICmp should be folded!");
5909 if (Constant *CI = dyn_cast<Constant>(Result))
5910 return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
5912 return BinaryOperator::createNot(Result);
5916 Instruction *InstCombiner::visitShl(BinaryOperator &I) {
5917 return commonShiftTransforms(I);
5920 Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
5921 return commonShiftTransforms(I);
5924 Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
5925 if (Instruction *R = commonShiftTransforms(I))
5928 Value *Op0 = I.getOperand(0);
5930 // ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
5931 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
5932 if (CSI->isAllOnesValue())
5933 return ReplaceInstUsesWith(I, CSI);
5935 // See if we can turn a signed shr into an unsigned shr.
5936 if (MaskedValueIsZero(Op0,
5937 APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())))
5938 return BinaryOperator::createLShr(Op0, I.getOperand(1));
5943 Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
5944 assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
5945 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
5947 // shl X, 0 == X and shr X, 0 == X
5948 // shl 0, X == 0 and shr 0, X == 0
5949 if (Op1 == Constant::getNullValue(Op1->getType()) ||
5950 Op0 == Constant::getNullValue(Op0->getType()))
5951 return ReplaceInstUsesWith(I, Op0);
5953 if (isa<UndefValue>(Op0)) {
5954 if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
5955 return ReplaceInstUsesWith(I, Op0);
5956 else // undef << X -> 0, undef >>u X -> 0
5957 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
5959 if (isa<UndefValue>(Op1)) {
5960 if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
5961 return ReplaceInstUsesWith(I, Op0);
5962 else // X << undef, X >>u undef -> 0
5963 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
5966 // Try to fold constant and into select arguments.
5967 if (isa<Constant>(Op0))
5968 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
5969 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
5972 if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
5973 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
5978 Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
5979 BinaryOperator &I) {
5980 bool isLeftShift = I.getOpcode() == Instruction::Shl;
5982 // See if we can simplify any instructions used by the instruction whose sole
5983 // purpose is to compute bits we don't care about.
5984 uint32_t TypeBits = Op0->getType()->getPrimitiveSizeInBits();
5985 APInt KnownZero(TypeBits, 0), KnownOne(TypeBits, 0);
5986 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(TypeBits),
5987 KnownZero, KnownOne))
5990 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
5991 // of a signed value.
5993 if (Op1->uge(TypeBits)) {
5994 if (I.getOpcode() != Instruction::AShr)
5995 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
5997 I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
6002 // ((X*C1) << C2) == (X * (C1 << C2))
6003 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
6004 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
6005 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
6006 return BinaryOperator::createMul(BO->getOperand(0),
6007 ConstantExpr::getShl(BOOp, Op1));
6009 // Try to fold constant and into select arguments.
6010 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
6011 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
6013 if (isa<PHINode>(Op0))
6014 if (Instruction *NV = FoldOpIntoPhi(I))
6017 if (Op0->hasOneUse()) {
6018 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
6019 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
6022 switch (Op0BO->getOpcode()) {
6024 case Instruction::Add:
6025 case Instruction::And:
6026 case Instruction::Or:
6027 case Instruction::Xor: {
6028 // These operators commute.
6029 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
6030 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
6031 match(Op0BO->getOperand(1),
6032 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
6033 Instruction *YS = BinaryOperator::createShl(
6034 Op0BO->getOperand(0), Op1,
6036 InsertNewInstBefore(YS, I); // (Y << C)
6038 BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
6039 Op0BO->getOperand(1)->getName());
6040 InsertNewInstBefore(X, I); // (X + (Y << C))
6041 uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
6042 return BinaryOperator::createAnd(X, ConstantInt::get(
6043 APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
6046 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
6047 Value *Op0BOOp1 = Op0BO->getOperand(1);
6048 if (isLeftShift && Op0BOOp1->hasOneUse() &&
6050 m_And(m_Shr(m_Value(V1), m_Value(V2)),m_ConstantInt(CC))) &&
6051 cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse() &&
6053 Instruction *YS = BinaryOperator::createShl(
6054 Op0BO->getOperand(0), Op1,
6056 InsertNewInstBefore(YS, I); // (Y << C)
6058 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
6059 V1->getName()+".mask");
6060 InsertNewInstBefore(XM, I); // X & (CC << C)
6062 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
6067 case Instruction::Sub: {
6068 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
6069 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
6070 match(Op0BO->getOperand(0),
6071 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
6072 Instruction *YS = BinaryOperator::createShl(
6073 Op0BO->getOperand(1), Op1,
6075 InsertNewInstBefore(YS, I); // (Y << C)
6077 BinaryOperator::create(Op0BO->getOpcode(), V1, YS,
6078 Op0BO->getOperand(0)->getName());
6079 InsertNewInstBefore(X, I); // (X + (Y << C))
6080 uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
6081 return BinaryOperator::createAnd(X, ConstantInt::get(
6082 APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
6085 // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
6086 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
6087 match(Op0BO->getOperand(0),
6088 m_And(m_Shr(m_Value(V1), m_Value(V2)),
6089 m_ConstantInt(CC))) && V2 == Op1 &&
6090 cast<BinaryOperator>(Op0BO->getOperand(0))
6091 ->getOperand(0)->hasOneUse()) {
6092 Instruction *YS = BinaryOperator::createShl(
6093 Op0BO->getOperand(1), Op1,
6095 InsertNewInstBefore(YS, I); // (Y << C)
6097 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
6098 V1->getName()+".mask");
6099 InsertNewInstBefore(XM, I); // X & (CC << C)
6101 return BinaryOperator::create(Op0BO->getOpcode(), XM, YS);
6109 // If the operand is an bitwise operator with a constant RHS, and the
6110 // shift is the only use, we can pull it out of the shift.
6111 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
6112 bool isValid = true; // Valid only for And, Or, Xor
6113 bool highBitSet = false; // Transform if high bit of constant set?
6115 switch (Op0BO->getOpcode()) {
6116 default: isValid = false; break; // Do not perform transform!
6117 case Instruction::Add:
6118 isValid = isLeftShift;
6120 case Instruction::Or:
6121 case Instruction::Xor:
6124 case Instruction::And:
6129 // If this is a signed shift right, and the high bit is modified
6130 // by the logical operation, do not perform the transformation.
6131 // The highBitSet boolean indicates the value of the high bit of
6132 // the constant which would cause it to be modified for this
6135 if (isValid && I.getOpcode() == Instruction::AShr)
6136 isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
6139 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
6141 Instruction *NewShift =
6142 BinaryOperator::create(I.getOpcode(), Op0BO->getOperand(0), Op1);
6143 InsertNewInstBefore(NewShift, I);
6144 NewShift->takeName(Op0BO);
6146 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
6153 // Find out if this is a shift of a shift by a constant.
6154 BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
6155 if (ShiftOp && !ShiftOp->isShift())
6158 if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
6159 ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
6160 uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
6161 uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
6162 assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
6163 if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
6164 Value *X = ShiftOp->getOperand(0);
6166 uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
6167 if (AmtSum > TypeBits)
6170 const IntegerType *Ty = cast<IntegerType>(I.getType());
6172 // Check for (X << c1) << c2 and (X >> c1) >> c2
6173 if (I.getOpcode() == ShiftOp->getOpcode()) {
6174 return BinaryOperator::create(I.getOpcode(), X,
6175 ConstantInt::get(Ty, AmtSum));
6176 } else if (ShiftOp->getOpcode() == Instruction::LShr &&
6177 I.getOpcode() == Instruction::AShr) {
6178 // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
6179 return BinaryOperator::createLShr(X, ConstantInt::get(Ty, AmtSum));
6180 } else if (ShiftOp->getOpcode() == Instruction::AShr &&
6181 I.getOpcode() == Instruction::LShr) {
6182 // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
6183 Instruction *Shift =
6184 BinaryOperator::createAShr(X, ConstantInt::get(Ty, AmtSum));
6185 InsertNewInstBefore(Shift, I);
6187 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
6188 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6191 // Okay, if we get here, one shift must be left, and the other shift must be
6192 // right. See if the amounts are equal.
6193 if (ShiftAmt1 == ShiftAmt2) {
6194 // If we have ((X >>? C) << C), turn this into X & (-1 << C).
6195 if (I.getOpcode() == Instruction::Shl) {
6196 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
6197 return BinaryOperator::createAnd(X, ConstantInt::get(Mask));
6199 // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
6200 if (I.getOpcode() == Instruction::LShr) {
6201 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
6202 return BinaryOperator::createAnd(X, ConstantInt::get(Mask));
6204 // We can simplify ((X << C) >>s C) into a trunc + sext.
6205 // NOTE: we could do this for any C, but that would make 'unusual' integer
6206 // types. For now, just stick to ones well-supported by the code
6208 const Type *SExtType = 0;
6209 switch (Ty->getBitWidth() - ShiftAmt1) {
6216 SExtType = IntegerType::get(Ty->getBitWidth() - ShiftAmt1);
6221 Instruction *NewTrunc = new TruncInst(X, SExtType, "sext");
6222 InsertNewInstBefore(NewTrunc, I);
6223 return new SExtInst(NewTrunc, Ty);
6225 // Otherwise, we can't handle it yet.
6226 } else if (ShiftAmt1 < ShiftAmt2) {
6227 uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
6229 // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
6230 if (I.getOpcode() == Instruction::Shl) {
6231 assert(ShiftOp->getOpcode() == Instruction::LShr ||
6232 ShiftOp->getOpcode() == Instruction::AShr);
6233 Instruction *Shift =
6234 BinaryOperator::createShl(X, ConstantInt::get(Ty, ShiftDiff));
6235 InsertNewInstBefore(Shift, I);
6237 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
6238 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6241 // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
6242 if (I.getOpcode() == Instruction::LShr) {
6243 assert(ShiftOp->getOpcode() == Instruction::Shl);
6244 Instruction *Shift =
6245 BinaryOperator::createLShr(X, ConstantInt::get(Ty, ShiftDiff));
6246 InsertNewInstBefore(Shift, I);
6248 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
6249 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6252 // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
6254 assert(ShiftAmt2 < ShiftAmt1);
6255 uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
6257 // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
6258 if (I.getOpcode() == Instruction::Shl) {
6259 assert(ShiftOp->getOpcode() == Instruction::LShr ||
6260 ShiftOp->getOpcode() == Instruction::AShr);
6261 Instruction *Shift =
6262 BinaryOperator::create(ShiftOp->getOpcode(), X,
6263 ConstantInt::get(Ty, ShiftDiff));
6264 InsertNewInstBefore(Shift, I);
6266 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
6267 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6270 // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
6271 if (I.getOpcode() == Instruction::LShr) {
6272 assert(ShiftOp->getOpcode() == Instruction::Shl);
6273 Instruction *Shift =
6274 BinaryOperator::createShl(X, ConstantInt::get(Ty, ShiftDiff));
6275 InsertNewInstBefore(Shift, I);
6277 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
6278 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6281 // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
6288 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
6289 /// expression. If so, decompose it, returning some value X, such that Val is
6292 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
6294 assert(Val->getType() == Type::Int32Ty && "Unexpected allocation size type!");
6295 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
6296 Offset = CI->getZExtValue();
6298 return ConstantInt::get(Type::Int32Ty, 0);
6299 } else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
6300 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
6301 if (I->getOpcode() == Instruction::Shl) {
6302 // This is a value scaled by '1 << the shift amt'.
6303 Scale = 1U << RHS->getZExtValue();
6305 return I->getOperand(0);
6306 } else if (I->getOpcode() == Instruction::Mul) {
6307 // This value is scaled by 'RHS'.
6308 Scale = RHS->getZExtValue();
6310 return I->getOperand(0);
6311 } else if (I->getOpcode() == Instruction::Add) {
6312 // We have X+C. Check to see if we really have (X*C2)+C1,
6313 // where C1 is divisible by C2.
6316 DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
6317 Offset += RHS->getZExtValue();
6324 // Otherwise, we can't look past this.
6331 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
6332 /// try to eliminate the cast by moving the type information into the alloc.
6333 Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
6334 AllocationInst &AI) {
6335 const PointerType *PTy = cast<PointerType>(CI.getType());
6337 // Remove any uses of AI that are dead.
6338 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
6340 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
6341 Instruction *User = cast<Instruction>(*UI++);
6342 if (isInstructionTriviallyDead(User)) {
6343 while (UI != E && *UI == User)
6344 ++UI; // If this instruction uses AI more than once, don't break UI.
6347 DOUT << "IC: DCE: " << *User;
6348 EraseInstFromFunction(*User);
6352 // Get the type really allocated and the type casted to.
6353 const Type *AllocElTy = AI.getAllocatedType();
6354 const Type *CastElTy = PTy->getElementType();
6355 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
6357 unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
6358 unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
6359 if (CastElTyAlign < AllocElTyAlign) return 0;
6361 // If the allocation has multiple uses, only promote it if we are strictly
6362 // increasing the alignment of the resultant allocation. If we keep it the
6363 // same, we open the door to infinite loops of various kinds.
6364 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
6366 uint64_t AllocElTySize = TD->getABITypeSize(AllocElTy);
6367 uint64_t CastElTySize = TD->getABITypeSize(CastElTy);
6368 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
6370 // See if we can satisfy the modulus by pulling a scale out of the array
6372 unsigned ArraySizeScale;
6374 Value *NumElements = // See if the array size is a decomposable linear expr.
6375 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
6377 // If we can now satisfy the modulus, by using a non-1 scale, we really can
6379 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
6380 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
6382 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
6387 // If the allocation size is constant, form a constant mul expression
6388 Amt = ConstantInt::get(Type::Int32Ty, Scale);
6389 if (isa<ConstantInt>(NumElements))
6390 Amt = Multiply(cast<ConstantInt>(NumElements), cast<ConstantInt>(Amt));
6391 // otherwise multiply the amount and the number of elements
6392 else if (Scale != 1) {
6393 Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
6394 Amt = InsertNewInstBefore(Tmp, AI);
6398 if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
6399 Value *Off = ConstantInt::get(Type::Int32Ty, Offset, true);
6400 Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
6401 Amt = InsertNewInstBefore(Tmp, AI);
6404 AllocationInst *New;
6405 if (isa<MallocInst>(AI))
6406 New = new MallocInst(CastElTy, Amt, AI.getAlignment());
6408 New = new AllocaInst(CastElTy, Amt, AI.getAlignment());
6409 InsertNewInstBefore(New, AI);
6412 // If the allocation has multiple uses, insert a cast and change all things
6413 // that used it to use the new cast. This will also hack on CI, but it will
6415 if (!AI.hasOneUse()) {
6416 AddUsesToWorkList(AI);
6417 // New is the allocation instruction, pointer typed. AI is the original
6418 // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
6419 CastInst *NewCast = new BitCastInst(New, AI.getType(), "tmpcast");
6420 InsertNewInstBefore(NewCast, AI);
6421 AI.replaceAllUsesWith(NewCast);
6423 return ReplaceInstUsesWith(CI, New);
6426 /// CanEvaluateInDifferentType - Return true if we can take the specified value
6427 /// and return it as type Ty without inserting any new casts and without
6428 /// changing the computed value. This is used by code that tries to decide
6429 /// whether promoting or shrinking integer operations to wider or smaller types
6430 /// will allow us to eliminate a truncate or extend.
6432 /// This is a truncation operation if Ty is smaller than V->getType(), or an
6433 /// extension operation if Ty is larger.
6434 static bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
6435 unsigned CastOpc, int &NumCastsRemoved) {
6436 // We can always evaluate constants in another type.
6437 if (isa<ConstantInt>(V))
6440 Instruction *I = dyn_cast<Instruction>(V);
6441 if (!I) return false;
6443 const IntegerType *OrigTy = cast<IntegerType>(V->getType());
6445 // If this is an extension or truncate, we can often eliminate it.
6446 if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
6447 // If this is a cast from the destination type, we can trivially eliminate
6448 // it, and this will remove a cast overall.
6449 if (I->getOperand(0)->getType() == Ty) {
6450 // If the first operand is itself a cast, and is eliminable, do not count
6451 // this as an eliminable cast. We would prefer to eliminate those two
6453 if (!isa<CastInst>(I->getOperand(0)))
6459 // We can't extend or shrink something that has multiple uses: doing so would
6460 // require duplicating the instruction in general, which isn't profitable.
6461 if (!I->hasOneUse()) return false;
6463 switch (I->getOpcode()) {
6464 case Instruction::Add:
6465 case Instruction::Sub:
6466 case Instruction::And:
6467 case Instruction::Or:
6468 case Instruction::Xor:
6469 // These operators can all arbitrarily be extended or truncated.
6470 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
6472 CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
6475 case Instruction::Shl:
6476 // If we are truncating the result of this SHL, and if it's a shift of a
6477 // constant amount, we can always perform a SHL in a smaller type.
6478 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
6479 uint32_t BitWidth = Ty->getBitWidth();
6480 if (BitWidth < OrigTy->getBitWidth() &&
6481 CI->getLimitedValue(BitWidth) < BitWidth)
6482 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
6486 case Instruction::LShr:
6487 // If this is a truncate of a logical shr, we can truncate it to a smaller
6488 // lshr iff we know that the bits we would otherwise be shifting in are
6490 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
6491 uint32_t OrigBitWidth = OrigTy->getBitWidth();
6492 uint32_t BitWidth = Ty->getBitWidth();
6493 if (BitWidth < OrigBitWidth &&
6494 MaskedValueIsZero(I->getOperand(0),
6495 APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
6496 CI->getLimitedValue(BitWidth) < BitWidth) {
6497 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
6502 case Instruction::ZExt:
6503 case Instruction::SExt:
6504 case Instruction::Trunc:
6505 // If this is the same kind of case as our original (e.g. zext+zext), we
6506 // can safely replace it. Note that replacing it does not reduce the number
6507 // of casts in the input.
6508 if (I->getOpcode() == CastOpc)
6513 // TODO: Can handle more cases here.
6520 /// EvaluateInDifferentType - Given an expression that
6521 /// CanEvaluateInDifferentType returns true for, actually insert the code to
6522 /// evaluate the expression.
6523 Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
6525 if (Constant *C = dyn_cast<Constant>(V))
6526 return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
6528 // Otherwise, it must be an instruction.
6529 Instruction *I = cast<Instruction>(V);
6530 Instruction *Res = 0;
6531 switch (I->getOpcode()) {
6532 case Instruction::Add:
6533 case Instruction::Sub:
6534 case Instruction::And:
6535 case Instruction::Or:
6536 case Instruction::Xor:
6537 case Instruction::AShr:
6538 case Instruction::LShr:
6539 case Instruction::Shl: {
6540 Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
6541 Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
6542 Res = BinaryOperator::create((Instruction::BinaryOps)I->getOpcode(),
6543 LHS, RHS, I->getName());
6546 case Instruction::Trunc:
6547 case Instruction::ZExt:
6548 case Instruction::SExt:
6549 // If the source type of the cast is the type we're trying for then we can
6550 // just return the source. There's no need to insert it because it is not
6552 if (I->getOperand(0)->getType() == Ty)
6553 return I->getOperand(0);
6555 // Otherwise, must be the same type of case, so just reinsert a new one.
6556 Res = CastInst::create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
6560 // TODO: Can handle more cases here.
6561 assert(0 && "Unreachable!");
6565 return InsertNewInstBefore(Res, *I);
6568 /// @brief Implement the transforms common to all CastInst visitors.
6569 Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
6570 Value *Src = CI.getOperand(0);
6572 // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
6573 // eliminate it now.
6574 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
6575 if (Instruction::CastOps opc =
6576 isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
6577 // The first cast (CSrc) is eliminable so we need to fix up or replace
6578 // the second cast (CI). CSrc will then have a good chance of being dead.
6579 return CastInst::create(opc, CSrc->getOperand(0), CI.getType());
6583 // If we are casting a select then fold the cast into the select
6584 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
6585 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
6588 // If we are casting a PHI then fold the cast into the PHI
6589 if (isa<PHINode>(Src))
6590 if (Instruction *NV = FoldOpIntoPhi(CI))
6596 /// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
6597 Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
6598 Value *Src = CI.getOperand(0);
6600 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
6601 // If casting the result of a getelementptr instruction with no offset, turn
6602 // this into a cast of the original pointer!
6603 if (GEP->hasAllZeroIndices()) {
6604 // Changing the cast operand is usually not a good idea but it is safe
6605 // here because the pointer operand is being replaced with another
6606 // pointer operand so the opcode doesn't need to change.
6608 CI.setOperand(0, GEP->getOperand(0));
6612 // If the GEP has a single use, and the base pointer is a bitcast, and the
6613 // GEP computes a constant offset, see if we can convert these three
6614 // instructions into fewer. This typically happens with unions and other
6615 // non-type-safe code.
6616 if (GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
6617 if (GEP->hasAllConstantIndices()) {
6618 // We are guaranteed to get a constant from EmitGEPOffset.
6619 ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, CI, *this));
6620 int64_t Offset = OffsetV->getSExtValue();
6622 // Get the base pointer input of the bitcast, and the type it points to.
6623 Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
6624 const Type *GEPIdxTy =
6625 cast<PointerType>(OrigBase->getType())->getElementType();
6626 if (GEPIdxTy->isSized()) {
6627 SmallVector<Value*, 8> NewIndices;
6629 // Start with the index over the outer type. Note that the type size
6630 // might be zero (even if the offset isn't zero) if the indexed type
6631 // is something like [0 x {int, int}]
6632 const Type *IntPtrTy = TD->getIntPtrType();
6633 int64_t FirstIdx = 0;
6634 if (int64_t TySize = TD->getABITypeSize(GEPIdxTy)) {
6635 FirstIdx = Offset/TySize;
6638 // Handle silly modulus not returning values values [0..TySize).
6642 assert(Offset >= 0);
6644 assert((uint64_t)Offset < (uint64_t)TySize &&"Out of range offset");
6647 NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
6649 // Index into the types. If we fail, set OrigBase to null.
6651 if (const StructType *STy = dyn_cast<StructType>(GEPIdxTy)) {
6652 const StructLayout *SL = TD->getStructLayout(STy);
6653 if (Offset < (int64_t)SL->getSizeInBytes()) {
6654 unsigned Elt = SL->getElementContainingOffset(Offset);
6655 NewIndices.push_back(ConstantInt::get(Type::Int32Ty, Elt));
6657 Offset -= SL->getElementOffset(Elt);
6658 GEPIdxTy = STy->getElementType(Elt);
6660 // Otherwise, we can't index into this, bail out.
6664 } else if (isa<ArrayType>(GEPIdxTy) || isa<VectorType>(GEPIdxTy)) {
6665 const SequentialType *STy = cast<SequentialType>(GEPIdxTy);
6666 if (uint64_t EltSize = TD->getABITypeSize(STy->getElementType())){
6667 NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
6670 NewIndices.push_back(ConstantInt::get(IntPtrTy, 0));
6672 GEPIdxTy = STy->getElementType();
6674 // Otherwise, we can't index into this, bail out.
6680 // If we were able to index down into an element, create the GEP
6681 // and bitcast the result. This eliminates one bitcast, potentially
6683 Instruction *NGEP = new GetElementPtrInst(OrigBase,
6685 NewIndices.end(), "");
6686 InsertNewInstBefore(NGEP, CI);
6687 NGEP->takeName(GEP);
6689 if (isa<BitCastInst>(CI))
6690 return new BitCastInst(NGEP, CI.getType());
6691 assert(isa<PtrToIntInst>(CI));
6692 return new PtrToIntInst(NGEP, CI.getType());
6699 return commonCastTransforms(CI);
6704 /// Only the TRUNC, ZEXT, SEXT, and BITCAST can both operand and result as
6705 /// integer types. This function implements the common transforms for all those
6707 /// @brief Implement the transforms common to CastInst with integer operands
6708 Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
6709 if (Instruction *Result = commonCastTransforms(CI))
6712 Value *Src = CI.getOperand(0);
6713 const Type *SrcTy = Src->getType();
6714 const Type *DestTy = CI.getType();
6715 uint32_t SrcBitSize = SrcTy->getPrimitiveSizeInBits();
6716 uint32_t DestBitSize = DestTy->getPrimitiveSizeInBits();
6718 // See if we can simplify any instructions used by the LHS whose sole
6719 // purpose is to compute bits we don't care about.
6720 APInt KnownZero(DestBitSize, 0), KnownOne(DestBitSize, 0);
6721 if (SimplifyDemandedBits(&CI, APInt::getAllOnesValue(DestBitSize),
6722 KnownZero, KnownOne))
6725 // If the source isn't an instruction or has more than one use then we
6726 // can't do anything more.
6727 Instruction *SrcI = dyn_cast<Instruction>(Src);
6728 if (!SrcI || !Src->hasOneUse())
6731 // Attempt to propagate the cast into the instruction for int->int casts.
6732 int NumCastsRemoved = 0;
6733 if (!isa<BitCastInst>(CI) &&
6734 CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy),
6735 CI.getOpcode(), NumCastsRemoved)) {
6736 // If this cast is a truncate, evaluting in a different type always
6737 // eliminates the cast, so it is always a win. If this is a zero-extension,
6738 // we need to do an AND to maintain the clear top-part of the computation,
6739 // so we require that the input have eliminated at least one cast. If this
6740 // is a sign extension, we insert two new casts (to do the extension) so we
6741 // require that two casts have been eliminated.
6743 switch (CI.getOpcode()) {
6745 // All the others use floating point so we shouldn't actually
6746 // get here because of the check above.
6747 assert(0 && "Unknown cast type");
6748 case Instruction::Trunc:
6751 case Instruction::ZExt:
6752 DoXForm = NumCastsRemoved >= 1;
6754 case Instruction::SExt:
6755 DoXForm = NumCastsRemoved >= 2;
6760 Value *Res = EvaluateInDifferentType(SrcI, DestTy,
6761 CI.getOpcode() == Instruction::SExt);
6762 assert(Res->getType() == DestTy);
6763 switch (CI.getOpcode()) {
6764 default: assert(0 && "Unknown cast type!");
6765 case Instruction::Trunc:
6766 case Instruction::BitCast:
6767 // Just replace this cast with the result.
6768 return ReplaceInstUsesWith(CI, Res);
6769 case Instruction::ZExt: {
6770 // We need to emit an AND to clear the high bits.
6771 assert(SrcBitSize < DestBitSize && "Not a zext?");
6772 Constant *C = ConstantInt::get(APInt::getLowBitsSet(DestBitSize,
6774 return BinaryOperator::createAnd(Res, C);
6776 case Instruction::SExt:
6777 // We need to emit a cast to truncate, then a cast to sext.
6778 return CastInst::create(Instruction::SExt,
6779 InsertCastBefore(Instruction::Trunc, Res, Src->getType(),
6785 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
6786 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
6788 switch (SrcI->getOpcode()) {
6789 case Instruction::Add:
6790 case Instruction::Mul:
6791 case Instruction::And:
6792 case Instruction::Or:
6793 case Instruction::Xor:
6794 // If we are discarding information, rewrite.
6795 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
6796 // Don't insert two casts if they cannot be eliminated. We allow
6797 // two casts to be inserted if the sizes are the same. This could
6798 // only be converting signedness, which is a noop.
6799 if (DestBitSize == SrcBitSize ||
6800 !ValueRequiresCast(CI.getOpcode(), Op1, DestTy,TD) ||
6801 !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
6802 Instruction::CastOps opcode = CI.getOpcode();
6803 Value *Op0c = InsertOperandCastBefore(opcode, Op0, DestTy, SrcI);
6804 Value *Op1c = InsertOperandCastBefore(opcode, Op1, DestTy, SrcI);
6805 return BinaryOperator::create(
6806 cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
6810 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
6811 if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
6812 SrcI->getOpcode() == Instruction::Xor &&
6813 Op1 == ConstantInt::getTrue() &&
6814 (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
6815 Value *New = InsertOperandCastBefore(Instruction::ZExt, Op0, DestTy, &CI);
6816 return BinaryOperator::createXor(New, ConstantInt::get(CI.getType(), 1));
6819 case Instruction::SDiv:
6820 case Instruction::UDiv:
6821 case Instruction::SRem:
6822 case Instruction::URem:
6823 // If we are just changing the sign, rewrite.
6824 if (DestBitSize == SrcBitSize) {
6825 // Don't insert two casts if they cannot be eliminated. We allow
6826 // two casts to be inserted if the sizes are the same. This could
6827 // only be converting signedness, which is a noop.
6828 if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
6829 !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
6830 Value *Op0c = InsertOperandCastBefore(Instruction::BitCast,
6832 Value *Op1c = InsertOperandCastBefore(Instruction::BitCast,
6834 return BinaryOperator::create(
6835 cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
6840 case Instruction::Shl:
6841 // Allow changing the sign of the source operand. Do not allow
6842 // changing the size of the shift, UNLESS the shift amount is a
6843 // constant. We must not change variable sized shifts to a smaller
6844 // size, because it is undefined to shift more bits out than exist
6846 if (DestBitSize == SrcBitSize ||
6847 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
6848 Instruction::CastOps opcode = (DestBitSize == SrcBitSize ?
6849 Instruction::BitCast : Instruction::Trunc);
6850 Value *Op0c = InsertOperandCastBefore(opcode, Op0, DestTy, SrcI);
6851 Value *Op1c = InsertOperandCastBefore(opcode, Op1, DestTy, SrcI);
6852 return BinaryOperator::createShl(Op0c, Op1c);
6855 case Instruction::AShr:
6856 // If this is a signed shr, and if all bits shifted in are about to be
6857 // truncated off, turn it into an unsigned shr to allow greater
6859 if (DestBitSize < SrcBitSize &&
6860 isa<ConstantInt>(Op1)) {
6861 uint32_t ShiftAmt = cast<ConstantInt>(Op1)->getLimitedValue(SrcBitSize);
6862 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
6863 // Insert the new logical shift right.
6864 return BinaryOperator::createLShr(Op0, Op1);
6872 Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
6873 if (Instruction *Result = commonIntCastTransforms(CI))
6876 Value *Src = CI.getOperand(0);
6877 const Type *Ty = CI.getType();
6878 uint32_t DestBitWidth = Ty->getPrimitiveSizeInBits();
6879 uint32_t SrcBitWidth = cast<IntegerType>(Src->getType())->getBitWidth();
6881 if (Instruction *SrcI = dyn_cast<Instruction>(Src)) {
6882 switch (SrcI->getOpcode()) {
6884 case Instruction::LShr:
6885 // We can shrink lshr to something smaller if we know the bits shifted in
6886 // are already zeros.
6887 if (ConstantInt *ShAmtV = dyn_cast<ConstantInt>(SrcI->getOperand(1))) {
6888 uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
6890 // Get a mask for the bits shifting in.
6891 APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
6892 Value* SrcIOp0 = SrcI->getOperand(0);
6893 if (SrcI->hasOneUse() && MaskedValueIsZero(SrcIOp0, Mask)) {
6894 if (ShAmt >= DestBitWidth) // All zeros.
6895 return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
6897 // Okay, we can shrink this. Truncate the input, then return a new
6899 Value *V1 = InsertCastBefore(Instruction::Trunc, SrcIOp0, Ty, CI);
6900 Value *V2 = InsertCastBefore(Instruction::Trunc, SrcI->getOperand(1),
6902 return BinaryOperator::createLShr(V1, V2);
6904 } else { // This is a variable shr.
6906 // Turn 'trunc (lshr X, Y) to bool' into '(X & (1 << Y)) != 0'. This is
6907 // more LLVM instructions, but allows '1 << Y' to be hoisted if
6908 // loop-invariant and CSE'd.
6909 if (CI.getType() == Type::Int1Ty && SrcI->hasOneUse()) {
6910 Value *One = ConstantInt::get(SrcI->getType(), 1);
6912 Value *V = InsertNewInstBefore(
6913 BinaryOperator::createShl(One, SrcI->getOperand(1),
6915 V = InsertNewInstBefore(BinaryOperator::createAnd(V,
6916 SrcI->getOperand(0),
6918 Value *Zero = Constant::getNullValue(V->getType());
6919 return new ICmpInst(ICmpInst::ICMP_NE, V, Zero);
6929 Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
6930 // If one of the common conversion will work ..
6931 if (Instruction *Result = commonIntCastTransforms(CI))
6934 Value *Src = CI.getOperand(0);
6936 // If this is a cast of a cast
6937 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
6938 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
6939 // types and if the sizes are just right we can convert this into a logical
6940 // 'and' which will be much cheaper than the pair of casts.
6941 if (isa<TruncInst>(CSrc)) {
6942 // Get the sizes of the types involved
6943 Value *A = CSrc->getOperand(0);
6944 uint32_t SrcSize = A->getType()->getPrimitiveSizeInBits();
6945 uint32_t MidSize = CSrc->getType()->getPrimitiveSizeInBits();
6946 uint32_t DstSize = CI.getType()->getPrimitiveSizeInBits();
6947 // If we're actually extending zero bits and the trunc is a no-op
6948 if (MidSize < DstSize && SrcSize == DstSize) {
6949 // Replace both of the casts with an And of the type mask.
6950 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
6951 Constant *AndConst = ConstantInt::get(AndValue);
6953 BinaryOperator::createAnd(CSrc->getOperand(0), AndConst);
6954 // Unfortunately, if the type changed, we need to cast it back.
6955 if (And->getType() != CI.getType()) {
6956 And->setName(CSrc->getName()+".mask");
6957 InsertNewInstBefore(And, CI);
6958 And = CastInst::createIntegerCast(And, CI.getType(), false/*ZExt*/);
6965 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) {
6966 // If we are just checking for a icmp eq of a single bit and zext'ing it
6967 // to an integer, then shift the bit to the appropriate place and then
6968 // cast to integer to avoid the comparison.
6969 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
6970 const APInt &Op1CV = Op1C->getValue();
6972 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
6973 // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
6974 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
6975 (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())){
6976 Value *In = ICI->getOperand(0);
6977 Value *Sh = ConstantInt::get(In->getType(),
6978 In->getType()->getPrimitiveSizeInBits()-1);
6979 In = InsertNewInstBefore(BinaryOperator::createLShr(In, Sh,
6980 In->getName()+".lobit"),
6982 if (In->getType() != CI.getType())
6983 In = CastInst::createIntegerCast(In, CI.getType(),
6984 false/*ZExt*/, "tmp", &CI);
6986 if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
6987 Constant *One = ConstantInt::get(In->getType(), 1);
6988 In = InsertNewInstBefore(BinaryOperator::createXor(In, One,
6989 In->getName()+".not"),
6993 return ReplaceInstUsesWith(CI, In);
6998 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
6999 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
7000 // zext (X == 1) to i32 --> X iff X has only the low bit set.
7001 // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
7002 // zext (X != 0) to i32 --> X iff X has only the low bit set.
7003 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
7004 // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
7005 // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
7006 if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
7007 // This only works for EQ and NE
7008 ICI->isEquality()) {
7009 // If Op1C some other power of two, convert:
7010 uint32_t BitWidth = Op1C->getType()->getBitWidth();
7011 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
7012 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
7013 ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
7015 APInt KnownZeroMask(~KnownZero);
7016 if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
7017 bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
7018 if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
7019 // (X&4) == 2 --> false
7020 // (X&4) != 2 --> true
7021 Constant *Res = ConstantInt::get(Type::Int1Ty, isNE);
7022 Res = ConstantExpr::getZExt(Res, CI.getType());
7023 return ReplaceInstUsesWith(CI, Res);
7026 uint32_t ShiftAmt = KnownZeroMask.logBase2();
7027 Value *In = ICI->getOperand(0);
7029 // Perform a logical shr by shiftamt.
7030 // Insert the shift to put the result in the low bit.
7031 In = InsertNewInstBefore(
7032 BinaryOperator::createLShr(In,
7033 ConstantInt::get(In->getType(), ShiftAmt),
7034 In->getName()+".lobit"), CI);
7037 if ((Op1CV != 0) == isNE) { // Toggle the low bit.
7038 Constant *One = ConstantInt::get(In->getType(), 1);
7039 In = BinaryOperator::createXor(In, One, "tmp");
7040 InsertNewInstBefore(cast<Instruction>(In), CI);
7043 if (CI.getType() == In->getType())
7044 return ReplaceInstUsesWith(CI, In);
7046 return CastInst::createIntegerCast(In, CI.getType(), false/*ZExt*/);
7054 Instruction *InstCombiner::visitSExt(SExtInst &CI) {
7055 if (Instruction *I = commonIntCastTransforms(CI))
7058 Value *Src = CI.getOperand(0);
7060 // sext (x <s 0) -> ashr x, 31 -> all ones if signed
7061 // sext (x >s -1) -> ashr x, 31 -> all ones if not signed
7062 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) {
7063 // If we are just checking for a icmp eq of a single bit and zext'ing it
7064 // to an integer, then shift the bit to the appropriate place and then
7065 // cast to integer to avoid the comparison.
7066 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
7067 const APInt &Op1CV = Op1C->getValue();
7069 // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
7070 // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
7071 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
7072 (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())){
7073 Value *In = ICI->getOperand(0);
7074 Value *Sh = ConstantInt::get(In->getType(),
7075 In->getType()->getPrimitiveSizeInBits()-1);
7076 In = InsertNewInstBefore(BinaryOperator::createAShr(In, Sh,
7077 In->getName()+".lobit"),
7079 if (In->getType() != CI.getType())
7080 In = CastInst::createIntegerCast(In, CI.getType(),
7081 true/*SExt*/, "tmp", &CI);
7083 if (ICI->getPredicate() == ICmpInst::ICMP_SGT)
7084 In = InsertNewInstBefore(BinaryOperator::createNot(In,
7085 In->getName()+".not"), CI);
7087 return ReplaceInstUsesWith(CI, In);
7095 Instruction *InstCombiner::visitFPTrunc(CastInst &CI) {
7096 return commonCastTransforms(CI);
7099 Instruction *InstCombiner::visitFPExt(CastInst &CI) {
7100 return commonCastTransforms(CI);
7103 Instruction *InstCombiner::visitFPToUI(CastInst &CI) {
7104 return commonCastTransforms(CI);
7107 Instruction *InstCombiner::visitFPToSI(CastInst &CI) {
7108 return commonCastTransforms(CI);
7111 Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
7112 return commonCastTransforms(CI);
7115 Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
7116 return commonCastTransforms(CI);
7119 Instruction *InstCombiner::visitPtrToInt(CastInst &CI) {
7120 return commonPointerCastTransforms(CI);
7123 Instruction *InstCombiner::visitIntToPtr(CastInst &CI) {
7124 return commonCastTransforms(CI);
7127 Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
7128 // If the operands are integer typed then apply the integer transforms,
7129 // otherwise just apply the common ones.
7130 Value *Src = CI.getOperand(0);
7131 const Type *SrcTy = Src->getType();
7132 const Type *DestTy = CI.getType();
7134 if (SrcTy->isInteger() && DestTy->isInteger()) {
7135 if (Instruction *Result = commonIntCastTransforms(CI))
7137 } else if (isa<PointerType>(SrcTy)) {
7138 if (Instruction *I = commonPointerCastTransforms(CI))
7141 if (Instruction *Result = commonCastTransforms(CI))
7146 // Get rid of casts from one type to the same type. These are useless and can
7147 // be replaced by the operand.
7148 if (DestTy == Src->getType())
7149 return ReplaceInstUsesWith(CI, Src);
7151 if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
7152 const PointerType *SrcPTy = cast<PointerType>(SrcTy);
7153 const Type *DstElTy = DstPTy->getElementType();
7154 const Type *SrcElTy = SrcPTy->getElementType();
7156 // If we are casting a malloc or alloca to a pointer to a type of the same
7157 // size, rewrite the allocation instruction to allocate the "right" type.
7158 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
7159 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
7162 // If the source and destination are pointers, and this cast is equivalent
7163 // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
7164 // This can enhance SROA and other transforms that want type-safe pointers.
7165 Constant *ZeroUInt = Constant::getNullValue(Type::Int32Ty);
7166 unsigned NumZeros = 0;
7167 while (SrcElTy != DstElTy &&
7168 isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
7169 SrcElTy->getNumContainedTypes() /* not "{}" */) {
7170 SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
7174 // If we found a path from the src to dest, create the getelementptr now.
7175 if (SrcElTy == DstElTy) {
7176 SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
7177 return new GetElementPtrInst(Src, Idxs.begin(), Idxs.end(), "",
7178 ((Instruction*) NULL));
7182 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
7183 if (SVI->hasOneUse()) {
7184 // Okay, we have (bitconvert (shuffle ..)). Check to see if this is
7185 // a bitconvert to a vector with the same # elts.
7186 if (isa<VectorType>(DestTy) &&
7187 cast<VectorType>(DestTy)->getNumElements() ==
7188 SVI->getType()->getNumElements()) {
7190 // If either of the operands is a cast from CI.getType(), then
7191 // evaluating the shuffle in the casted destination's type will allow
7192 // us to eliminate at least one cast.
7193 if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
7194 Tmp->getOperand(0)->getType() == DestTy) ||
7195 ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
7196 Tmp->getOperand(0)->getType() == DestTy)) {
7197 Value *LHS = InsertOperandCastBefore(Instruction::BitCast,
7198 SVI->getOperand(0), DestTy, &CI);
7199 Value *RHS = InsertOperandCastBefore(Instruction::BitCast,
7200 SVI->getOperand(1), DestTy, &CI);
7201 // Return a new shuffle vector. Use the same element ID's, as we
7202 // know the vector types match #elts.
7203 return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
7211 /// GetSelectFoldableOperands - We want to turn code that looks like this:
7213 /// %D = select %cond, %C, %A
7215 /// %C = select %cond, %B, 0
7218 /// Assuming that the specified instruction is an operand to the select, return
7219 /// a bitmask indicating which operands of this instruction are foldable if they
7220 /// equal the other incoming value of the select.
7222 static unsigned GetSelectFoldableOperands(Instruction *I) {
7223 switch (I->getOpcode()) {
7224 case Instruction::Add:
7225 case Instruction::Mul:
7226 case Instruction::And:
7227 case Instruction::Or:
7228 case Instruction::Xor:
7229 return 3; // Can fold through either operand.
7230 case Instruction::Sub: // Can only fold on the amount subtracted.
7231 case Instruction::Shl: // Can only fold on the shift amount.
7232 case Instruction::LShr:
7233 case Instruction::AShr:
7236 return 0; // Cannot fold
7240 /// GetSelectFoldableConstant - For the same transformation as the previous
7241 /// function, return the identity constant that goes into the select.
7242 static Constant *GetSelectFoldableConstant(Instruction *I) {
7243 switch (I->getOpcode()) {
7244 default: assert(0 && "This cannot happen!"); abort();
7245 case Instruction::Add:
7246 case Instruction::Sub:
7247 case Instruction::Or:
7248 case Instruction::Xor:
7249 case Instruction::Shl:
7250 case Instruction::LShr:
7251 case Instruction::AShr:
7252 return Constant::getNullValue(I->getType());
7253 case Instruction::And:
7254 return Constant::getAllOnesValue(I->getType());
7255 case Instruction::Mul:
7256 return ConstantInt::get(I->getType(), 1);
7260 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
7261 /// have the same opcode and only one use each. Try to simplify this.
7262 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
7264 if (TI->getNumOperands() == 1) {
7265 // If this is a non-volatile load or a cast from the same type,
7268 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
7271 return 0; // unknown unary op.
7274 // Fold this by inserting a select from the input values.
7275 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
7276 FI->getOperand(0), SI.getName()+".v");
7277 InsertNewInstBefore(NewSI, SI);
7278 return CastInst::create(Instruction::CastOps(TI->getOpcode()), NewSI,
7282 // Only handle binary operators here.
7283 if (!isa<BinaryOperator>(TI))
7286 // Figure out if the operations have any operands in common.
7287 Value *MatchOp, *OtherOpT, *OtherOpF;
7289 if (TI->getOperand(0) == FI->getOperand(0)) {
7290 MatchOp = TI->getOperand(0);
7291 OtherOpT = TI->getOperand(1);
7292 OtherOpF = FI->getOperand(1);
7293 MatchIsOpZero = true;
7294 } else if (TI->getOperand(1) == FI->getOperand(1)) {
7295 MatchOp = TI->getOperand(1);
7296 OtherOpT = TI->getOperand(0);
7297 OtherOpF = FI->getOperand(0);
7298 MatchIsOpZero = false;
7299 } else if (!TI->isCommutative()) {
7301 } else if (TI->getOperand(0) == FI->getOperand(1)) {
7302 MatchOp = TI->getOperand(0);
7303 OtherOpT = TI->getOperand(1);
7304 OtherOpF = FI->getOperand(0);
7305 MatchIsOpZero = true;
7306 } else if (TI->getOperand(1) == FI->getOperand(0)) {
7307 MatchOp = TI->getOperand(1);
7308 OtherOpT = TI->getOperand(0);
7309 OtherOpF = FI->getOperand(1);
7310 MatchIsOpZero = true;
7315 // If we reach here, they do have operations in common.
7316 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
7317 OtherOpF, SI.getName()+".v");
7318 InsertNewInstBefore(NewSI, SI);
7320 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
7322 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
7324 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
7326 assert(0 && "Shouldn't get here");
7330 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
7331 Value *CondVal = SI.getCondition();
7332 Value *TrueVal = SI.getTrueValue();
7333 Value *FalseVal = SI.getFalseValue();
7335 // select true, X, Y -> X
7336 // select false, X, Y -> Y
7337 if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
7338 return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
7340 // select C, X, X -> X
7341 if (TrueVal == FalseVal)
7342 return ReplaceInstUsesWith(SI, TrueVal);
7344 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
7345 return ReplaceInstUsesWith(SI, FalseVal);
7346 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
7347 return ReplaceInstUsesWith(SI, TrueVal);
7348 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
7349 if (isa<Constant>(TrueVal))
7350 return ReplaceInstUsesWith(SI, TrueVal);
7352 return ReplaceInstUsesWith(SI, FalseVal);
7355 if (SI.getType() == Type::Int1Ty) {
7356 if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
7357 if (C->getZExtValue()) {
7358 // Change: A = select B, true, C --> A = or B, C
7359 return BinaryOperator::createOr(CondVal, FalseVal);
7361 // Change: A = select B, false, C --> A = and !B, C
7363 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
7364 "not."+CondVal->getName()), SI);
7365 return BinaryOperator::createAnd(NotCond, FalseVal);
7367 } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
7368 if (C->getZExtValue() == false) {
7369 // Change: A = select B, C, false --> A = and B, C
7370 return BinaryOperator::createAnd(CondVal, TrueVal);
7372 // Change: A = select B, C, true --> A = or !B, C
7374 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
7375 "not."+CondVal->getName()), SI);
7376 return BinaryOperator::createOr(NotCond, TrueVal);
7380 // select a, b, a -> a&b
7381 // select a, a, b -> a|b
7382 if (CondVal == TrueVal)
7383 return BinaryOperator::createOr(CondVal, FalseVal);
7384 else if (CondVal == FalseVal)
7385 return BinaryOperator::createAnd(CondVal, TrueVal);
7388 // Selecting between two integer constants?
7389 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
7390 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
7391 // select C, 1, 0 -> zext C to int
7392 if (FalseValC->isZero() && TrueValC->getValue() == 1) {
7393 return CastInst::create(Instruction::ZExt, CondVal, SI.getType());
7394 } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
7395 // select C, 0, 1 -> zext !C to int
7397 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
7398 "not."+CondVal->getName()), SI);
7399 return CastInst::create(Instruction::ZExt, NotCond, SI.getType());
7402 // FIXME: Turn select 0/-1 and -1/0 into sext from condition!
7404 if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
7406 // (x <s 0) ? -1 : 0 -> ashr x, 31
7407 if (TrueValC->isAllOnesValue() && FalseValC->isZero())
7408 if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) {
7409 if (IC->getPredicate() == ICmpInst::ICMP_SLT && CmpCst->isZero()) {
7410 // The comparison constant and the result are not neccessarily the
7411 // same width. Make an all-ones value by inserting a AShr.
7412 Value *X = IC->getOperand(0);
7413 uint32_t Bits = X->getType()->getPrimitiveSizeInBits();
7414 Constant *ShAmt = ConstantInt::get(X->getType(), Bits-1);
7415 Instruction *SRA = BinaryOperator::create(Instruction::AShr, X,
7417 InsertNewInstBefore(SRA, SI);
7419 // Finally, convert to the type of the select RHS. We figure out
7420 // if this requires a SExt, Trunc or BitCast based on the sizes.
7421 Instruction::CastOps opc = Instruction::BitCast;
7422 uint32_t SRASize = SRA->getType()->getPrimitiveSizeInBits();
7423 uint32_t SISize = SI.getType()->getPrimitiveSizeInBits();
7424 if (SRASize < SISize)
7425 opc = Instruction::SExt;
7426 else if (SRASize > SISize)
7427 opc = Instruction::Trunc;
7428 return CastInst::create(opc, SRA, SI.getType());
7433 // If one of the constants is zero (we know they can't both be) and we
7434 // have an icmp instruction with zero, and we have an 'and' with the
7435 // non-constant value, eliminate this whole mess. This corresponds to
7436 // cases like this: ((X & 27) ? 27 : 0)
7437 if (TrueValC->isZero() || FalseValC->isZero())
7438 if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
7439 cast<Constant>(IC->getOperand(1))->isNullValue())
7440 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
7441 if (ICA->getOpcode() == Instruction::And &&
7442 isa<ConstantInt>(ICA->getOperand(1)) &&
7443 (ICA->getOperand(1) == TrueValC ||
7444 ICA->getOperand(1) == FalseValC) &&
7445 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
7446 // Okay, now we know that everything is set up, we just don't
7447 // know whether we have a icmp_ne or icmp_eq and whether the
7448 // true or false val is the zero.
7449 bool ShouldNotVal = !TrueValC->isZero();
7450 ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
7453 V = InsertNewInstBefore(BinaryOperator::create(
7454 Instruction::Xor, V, ICA->getOperand(1)), SI);
7455 return ReplaceInstUsesWith(SI, V);
7460 // See if we are selecting two values based on a comparison of the two values.
7461 if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
7462 if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
7463 // Transform (X == Y) ? X : Y -> Y
7464 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
7465 // This is not safe in general for floating point:
7466 // consider X== -0, Y== +0.
7467 // It becomes safe if either operand is a nonzero constant.
7468 ConstantFP *CFPt, *CFPf;
7469 if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
7470 !CFPt->getValueAPF().isZero()) ||
7471 ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
7472 !CFPf->getValueAPF().isZero()))
7473 return ReplaceInstUsesWith(SI, FalseVal);
7475 // Transform (X != Y) ? X : Y -> X
7476 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
7477 return ReplaceInstUsesWith(SI, TrueVal);
7478 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7480 } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
7481 // Transform (X == Y) ? Y : X -> X
7482 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
7483 // This is not safe in general for floating point:
7484 // consider X== -0, Y== +0.
7485 // It becomes safe if either operand is a nonzero constant.
7486 ConstantFP *CFPt, *CFPf;
7487 if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
7488 !CFPt->getValueAPF().isZero()) ||
7489 ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
7490 !CFPf->getValueAPF().isZero()))
7491 return ReplaceInstUsesWith(SI, FalseVal);
7493 // Transform (X != Y) ? Y : X -> Y
7494 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
7495 return ReplaceInstUsesWith(SI, TrueVal);
7496 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7500 // See if we are selecting two values based on a comparison of the two values.
7501 if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal)) {
7502 if (ICI->getOperand(0) == TrueVal && ICI->getOperand(1) == FalseVal) {
7503 // Transform (X == Y) ? X : Y -> Y
7504 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
7505 return ReplaceInstUsesWith(SI, FalseVal);
7506 // Transform (X != Y) ? X : Y -> X
7507 if (ICI->getPredicate() == ICmpInst::ICMP_NE)
7508 return ReplaceInstUsesWith(SI, TrueVal);
7509 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7511 } else if (ICI->getOperand(0) == FalseVal && ICI->getOperand(1) == TrueVal){
7512 // Transform (X == Y) ? Y : X -> X
7513 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
7514 return ReplaceInstUsesWith(SI, FalseVal);
7515 // Transform (X != Y) ? Y : X -> Y
7516 if (ICI->getPredicate() == ICmpInst::ICMP_NE)
7517 return ReplaceInstUsesWith(SI, TrueVal);
7518 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7522 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
7523 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
7524 if (TI->hasOneUse() && FI->hasOneUse()) {
7525 Instruction *AddOp = 0, *SubOp = 0;
7527 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
7528 if (TI->getOpcode() == FI->getOpcode())
7529 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
7532 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
7533 // even legal for FP.
7534 if (TI->getOpcode() == Instruction::Sub &&
7535 FI->getOpcode() == Instruction::Add) {
7536 AddOp = FI; SubOp = TI;
7537 } else if (FI->getOpcode() == Instruction::Sub &&
7538 TI->getOpcode() == Instruction::Add) {
7539 AddOp = TI; SubOp = FI;
7543 Value *OtherAddOp = 0;
7544 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
7545 OtherAddOp = AddOp->getOperand(1);
7546 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
7547 OtherAddOp = AddOp->getOperand(0);
7551 // So at this point we know we have (Y -> OtherAddOp):
7552 // select C, (add X, Y), (sub X, Z)
7553 Value *NegVal; // Compute -Z
7554 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
7555 NegVal = ConstantExpr::getNeg(C);
7557 NegVal = InsertNewInstBefore(
7558 BinaryOperator::createNeg(SubOp->getOperand(1), "tmp"), SI);
7561 Value *NewTrueOp = OtherAddOp;
7562 Value *NewFalseOp = NegVal;
7564 std::swap(NewTrueOp, NewFalseOp);
7565 Instruction *NewSel =
7566 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
7568 NewSel = InsertNewInstBefore(NewSel, SI);
7569 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
7574 // See if we can fold the select into one of our operands.
7575 if (SI.getType()->isInteger()) {
7576 // See the comment above GetSelectFoldableOperands for a description of the
7577 // transformation we are doing here.
7578 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
7579 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
7580 !isa<Constant>(FalseVal))
7581 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
7582 unsigned OpToFold = 0;
7583 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
7585 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
7590 Constant *C = GetSelectFoldableConstant(TVI);
7591 Instruction *NewSel =
7592 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C);
7593 InsertNewInstBefore(NewSel, SI);
7594 NewSel->takeName(TVI);
7595 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
7596 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
7598 assert(0 && "Unknown instruction!!");
7603 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
7604 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
7605 !isa<Constant>(TrueVal))
7606 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
7607 unsigned OpToFold = 0;
7608 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
7610 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
7615 Constant *C = GetSelectFoldableConstant(FVI);
7616 Instruction *NewSel =
7617 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold));
7618 InsertNewInstBefore(NewSel, SI);
7619 NewSel->takeName(FVI);
7620 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
7621 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
7623 assert(0 && "Unknown instruction!!");
7628 if (BinaryOperator::isNot(CondVal)) {
7629 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
7630 SI.setOperand(1, FalseVal);
7631 SI.setOperand(2, TrueVal);
7638 /// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
7639 /// we can determine, return it, otherwise return 0. If PrefAlign is specified,
7640 /// and it is more than the alignment of the ultimate object, see if we can
7641 /// increase the alignment of the ultimate object, making this check succeed.
7642 static unsigned GetOrEnforceKnownAlignment(Value *V, TargetData *TD,
7643 unsigned PrefAlign = 0) {
7644 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
7645 unsigned Align = GV->getAlignment();
7646 if (Align == 0 && TD && GV->getType()->getElementType()->isSized())
7647 Align = TD->getPrefTypeAlignment(GV->getType()->getElementType());
7649 // If there is a large requested alignment and we can, bump up the alignment
7651 if (PrefAlign > Align && GV->hasInitializer()) {
7652 GV->setAlignment(PrefAlign);
7656 } else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
7657 unsigned Align = AI->getAlignment();
7658 if (Align == 0 && TD) {
7659 if (isa<AllocaInst>(AI))
7660 Align = TD->getPrefTypeAlignment(AI->getType()->getElementType());
7661 else if (isa<MallocInst>(AI)) {
7662 // Malloc returns maximally aligned memory.
7663 Align = TD->getABITypeAlignment(AI->getType()->getElementType());
7666 (unsigned)TD->getABITypeAlignment(Type::DoubleTy));
7669 (unsigned)TD->getABITypeAlignment(Type::Int64Ty));
7673 // If there is a requested alignment and if this is an alloca, round up. We
7674 // don't do this for malloc, because some systems can't respect the request.
7675 if (PrefAlign > Align && isa<AllocaInst>(AI)) {
7676 AI->setAlignment(PrefAlign);
7680 } else if (isa<BitCastInst>(V) ||
7681 (isa<ConstantExpr>(V) &&
7682 cast<ConstantExpr>(V)->getOpcode() == Instruction::BitCast)) {
7683 return GetOrEnforceKnownAlignment(cast<User>(V)->getOperand(0),
7685 } else if (User *GEPI = dyn_castGetElementPtr(V)) {
7686 // If all indexes are zero, it is just the alignment of the base pointer.
7687 bool AllZeroOperands = true;
7688 for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
7689 if (!isa<Constant>(GEPI->getOperand(i)) ||
7690 !cast<Constant>(GEPI->getOperand(i))->isNullValue()) {
7691 AllZeroOperands = false;
7695 if (AllZeroOperands) {
7696 // Treat this like a bitcast.
7697 return GetOrEnforceKnownAlignment(GEPI->getOperand(0), TD, PrefAlign);
7700 unsigned BaseAlignment = GetOrEnforceKnownAlignment(GEPI->getOperand(0),TD);
7701 if (BaseAlignment == 0) return 0;
7703 // Otherwise, if the base alignment is >= the alignment we expect for the
7704 // base pointer type, then we know that the resultant pointer is aligned at
7705 // least as much as its type requires.
7708 const Type *BasePtrTy = GEPI->getOperand(0)->getType();
7709 const PointerType *PtrTy = cast<PointerType>(BasePtrTy);
7710 unsigned Align = TD->getABITypeAlignment(PtrTy->getElementType());
7711 if (Align <= BaseAlignment) {
7712 const Type *GEPTy = GEPI->getType();
7713 const PointerType *GEPPtrTy = cast<PointerType>(GEPTy);
7714 Align = std::min(Align, (unsigned)
7715 TD->getABITypeAlignment(GEPPtrTy->getElementType()));
7724 /// visitCallInst - CallInst simplification. This mostly only handles folding
7725 /// of intrinsic instructions. For normal calls, it allows visitCallSite to do
7726 /// the heavy lifting.
7728 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
7729 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
7730 if (!II) return visitCallSite(&CI);
7732 // Intrinsics cannot occur in an invoke, so handle them here instead of in
7734 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
7735 bool Changed = false;
7737 // memmove/cpy/set of zero bytes is a noop.
7738 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
7739 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
7741 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
7742 if (CI->getZExtValue() == 1) {
7743 // Replace the instruction with just byte operations. We would
7744 // transform other cases to loads/stores, but we don't know if
7745 // alignment is sufficient.
7749 // If we have a memmove and the source operation is a constant global,
7750 // then the source and dest pointers can't alias, so we can change this
7751 // into a call to memcpy.
7752 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(II)) {
7753 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
7754 if (GVSrc->isConstant()) {
7755 Module *M = CI.getParent()->getParent()->getParent();
7757 if (CI.getCalledFunction()->getFunctionType()->getParamType(2) ==
7759 Name = "llvm.memcpy.i32";
7761 Name = "llvm.memcpy.i64";
7762 Constant *MemCpy = M->getOrInsertFunction(Name,
7763 CI.getCalledFunction()->getFunctionType());
7764 CI.setOperand(0, MemCpy);
7769 // If we can determine a pointer alignment that is bigger than currently
7770 // set, update the alignment.
7771 if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) {
7772 unsigned Alignment1 = GetOrEnforceKnownAlignment(MI->getOperand(1), TD);
7773 unsigned Alignment2 = GetOrEnforceKnownAlignment(MI->getOperand(2), TD);
7774 unsigned Align = std::min(Alignment1, Alignment2);
7775 if (MI->getAlignment()->getZExtValue() < Align) {
7776 MI->setAlignment(ConstantInt::get(Type::Int32Ty, Align));
7780 // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
7782 ConstantInt *MemOpLength = dyn_cast<ConstantInt>(CI.getOperand(3));
7784 unsigned Size = MemOpLength->getZExtValue();
7785 unsigned Align = cast<ConstantInt>(CI.getOperand(4))->getZExtValue();
7786 PointerType *NewPtrTy = NULL;
7787 // Destination pointer type is always i8 *
7788 // If Size is 8 then use Int64Ty
7789 // If Size is 4 then use Int32Ty
7790 // If Size is 2 then use Int16Ty
7791 // If Size is 1 then use Int8Ty
7792 if (Size && Size <=8 && !(Size&(Size-1)))
7793 NewPtrTy = PointerType::getUnqual(IntegerType::get(Size<<3));
7796 Value *Src = InsertCastBefore(Instruction::BitCast, CI.getOperand(2),
7798 Value *Dest = InsertCastBefore(Instruction::BitCast, CI.getOperand(1),
7800 Value *L = new LoadInst(Src, "tmp", false, Align, &CI);
7801 Value *NS = new StoreInst(L, Dest, false, Align, &CI);
7802 CI.replaceAllUsesWith(NS);
7804 return EraseInstFromFunction(CI);
7807 } else if (isa<MemSetInst>(MI)) {
7808 unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest(), TD);
7809 if (MI->getAlignment()->getZExtValue() < Alignment) {
7810 MI->setAlignment(ConstantInt::get(Type::Int32Ty, Alignment));
7815 if (Changed) return II;
7817 switch (II->getIntrinsicID()) {
7819 case Intrinsic::ppc_altivec_lvx:
7820 case Intrinsic::ppc_altivec_lvxl:
7821 case Intrinsic::x86_sse_loadu_ps:
7822 case Intrinsic::x86_sse2_loadu_pd:
7823 case Intrinsic::x86_sse2_loadu_dq:
7824 // Turn PPC lvx -> load if the pointer is known aligned.
7825 // Turn X86 loadups -> load if the pointer is known aligned.
7826 if (GetOrEnforceKnownAlignment(II->getOperand(1), TD, 16) >= 16) {
7828 InsertCastBefore(Instruction::BitCast, II->getOperand(1),
7829 PointerType::getUnqual(II->getType()), CI);
7830 return new LoadInst(Ptr);
7833 case Intrinsic::ppc_altivec_stvx:
7834 case Intrinsic::ppc_altivec_stvxl:
7835 // Turn stvx -> store if the pointer is known aligned.
7836 if (GetOrEnforceKnownAlignment(II->getOperand(2), TD, 16) >= 16) {
7837 const Type *OpPtrTy =
7838 PointerType::getUnqual(II->getOperand(1)->getType());
7839 Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(2),
7841 return new StoreInst(II->getOperand(1), Ptr);
7844 case Intrinsic::x86_sse_storeu_ps:
7845 case Intrinsic::x86_sse2_storeu_pd:
7846 case Intrinsic::x86_sse2_storeu_dq:
7847 case Intrinsic::x86_sse2_storel_dq:
7848 // Turn X86 storeu -> store if the pointer is known aligned.
7849 if (GetOrEnforceKnownAlignment(II->getOperand(1), TD, 16) >= 16) {
7850 const Type *OpPtrTy =
7851 PointerType::getUnqual(II->getOperand(2)->getType());
7852 Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
7854 return new StoreInst(II->getOperand(2), Ptr);
7858 case Intrinsic::x86_sse_cvttss2si: {
7859 // These intrinsics only demands the 0th element of its input vector. If
7860 // we can simplify the input based on that, do so now.
7862 if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), 1,
7864 II->setOperand(1, V);
7870 case Intrinsic::ppc_altivec_vperm:
7871 // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
7872 if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
7873 assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
7875 // Check that all of the elements are integer constants or undefs.
7876 bool AllEltsOk = true;
7877 for (unsigned i = 0; i != 16; ++i) {
7878 if (!isa<ConstantInt>(Mask->getOperand(i)) &&
7879 !isa<UndefValue>(Mask->getOperand(i))) {
7886 // Cast the input vectors to byte vectors.
7887 Value *Op0 = InsertCastBefore(Instruction::BitCast,
7888 II->getOperand(1), Mask->getType(), CI);
7889 Value *Op1 = InsertCastBefore(Instruction::BitCast,
7890 II->getOperand(2), Mask->getType(), CI);
7891 Value *Result = UndefValue::get(Op0->getType());
7893 // Only extract each element once.
7894 Value *ExtractedElts[32];
7895 memset(ExtractedElts, 0, sizeof(ExtractedElts));
7897 for (unsigned i = 0; i != 16; ++i) {
7898 if (isa<UndefValue>(Mask->getOperand(i)))
7900 unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
7901 Idx &= 31; // Match the hardware behavior.
7903 if (ExtractedElts[Idx] == 0) {
7905 new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp");
7906 InsertNewInstBefore(Elt, CI);
7907 ExtractedElts[Idx] = Elt;
7910 // Insert this value into the result vector.
7911 Result = new InsertElementInst(Result, ExtractedElts[Idx], i,"tmp");
7912 InsertNewInstBefore(cast<Instruction>(Result), CI);
7914 return CastInst::create(Instruction::BitCast, Result, CI.getType());
7919 case Intrinsic::stackrestore: {
7920 // If the save is right next to the restore, remove the restore. This can
7921 // happen when variable allocas are DCE'd.
7922 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
7923 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
7924 BasicBlock::iterator BI = SS;
7926 return EraseInstFromFunction(CI);
7930 // If the stack restore is in a return/unwind block and if there are no
7931 // allocas or calls between the restore and the return, nuke the restore.
7932 TerminatorInst *TI = II->getParent()->getTerminator();
7933 if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) {
7934 BasicBlock::iterator BI = II;
7935 bool CannotRemove = false;
7936 for (++BI; &*BI != TI; ++BI) {
7937 if (isa<AllocaInst>(BI) ||
7938 (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) {
7939 CannotRemove = true;
7944 return EraseInstFromFunction(CI);
7951 return visitCallSite(II);
7954 // InvokeInst simplification
7956 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
7957 return visitCallSite(&II);
7960 // visitCallSite - Improvements for call and invoke instructions.
7962 Instruction *InstCombiner::visitCallSite(CallSite CS) {
7963 bool Changed = false;
7965 // If the callee is a constexpr cast of a function, attempt to move the cast
7966 // to the arguments of the call/invoke.
7967 if (transformConstExprCastCall(CS)) return 0;
7969 Value *Callee = CS.getCalledValue();
7971 if (Function *CalleeF = dyn_cast<Function>(Callee))
7972 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
7973 Instruction *OldCall = CS.getInstruction();
7974 // If the call and callee calling conventions don't match, this call must
7975 // be unreachable, as the call is undefined.
7976 new StoreInst(ConstantInt::getTrue(),
7977 UndefValue::get(PointerType::getUnqual(Type::Int1Ty)),
7979 if (!OldCall->use_empty())
7980 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
7981 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
7982 return EraseInstFromFunction(*OldCall);
7986 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
7987 // This instruction is not reachable, just remove it. We insert a store to
7988 // undef so that we know that this code is not reachable, despite the fact
7989 // that we can't modify the CFG here.
7990 new StoreInst(ConstantInt::getTrue(),
7991 UndefValue::get(PointerType::getUnqual(Type::Int1Ty)),
7992 CS.getInstruction());
7994 if (!CS.getInstruction()->use_empty())
7995 CS.getInstruction()->
7996 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
7998 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
7999 // Don't break the CFG, insert a dummy cond branch.
8000 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
8001 ConstantInt::getTrue(), II);
8003 return EraseInstFromFunction(*CS.getInstruction());
8006 if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee))
8007 if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0)))
8008 if (In->getIntrinsicID() == Intrinsic::init_trampoline)
8009 return transformCallThroughTrampoline(CS);
8011 const PointerType *PTy = cast<PointerType>(Callee->getType());
8012 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
8013 if (FTy->isVarArg()) {
8014 // See if we can optimize any arguments passed through the varargs area of
8016 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
8017 E = CS.arg_end(); I != E; ++I)
8018 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
8019 // If this cast does not effect the value passed through the varargs
8020 // area, we can eliminate the use of the cast.
8021 Value *Op = CI->getOperand(0);
8022 if (CI->isLosslessCast()) {
8029 if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
8030 // Inline asm calls cannot throw - mark them 'nounwind'.
8031 CS.setDoesNotThrow();
8035 return Changed ? CS.getInstruction() : 0;
8038 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
8039 // attempt to move the cast to the arguments of the call/invoke.
8041 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
8042 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
8043 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
8044 if (CE->getOpcode() != Instruction::BitCast ||
8045 !isa<Function>(CE->getOperand(0)))
8047 Function *Callee = cast<Function>(CE->getOperand(0));
8048 Instruction *Caller = CS.getInstruction();
8050 // Okay, this is a cast from a function to a different type. Unless doing so
8051 // would cause a type conversion of one of our arguments, change this call to
8052 // be a direct call with arguments casted to the appropriate types.
8054 const FunctionType *FT = Callee->getFunctionType();
8055 const Type *OldRetTy = Caller->getType();
8057 const ParamAttrsList* CallerPAL = 0;
8058 if (CallInst *CallerCI = dyn_cast<CallInst>(Caller))
8059 CallerPAL = CallerCI->getParamAttrs();
8060 else if (InvokeInst *CallerII = dyn_cast<InvokeInst>(Caller))
8061 CallerPAL = CallerII->getParamAttrs();
8063 // If the parameter attributes are not compatible, don't do the xform. We
8064 // don't want to lose an sret attribute or something.
8065 if (!ParamAttrsList::areCompatible(CallerPAL, Callee->getParamAttrs()))
8068 // Check to see if we are changing the return type...
8069 if (OldRetTy != FT->getReturnType()) {
8070 if (Callee->isDeclaration() && !Caller->use_empty() &&
8071 // Conversion is ok if changing from pointer to int of same size.
8072 !(isa<PointerType>(FT->getReturnType()) &&
8073 TD->getIntPtrType() == OldRetTy))
8074 return false; // Cannot transform this return value.
8076 // If the callsite is an invoke instruction, and the return value is used by
8077 // a PHI node in a successor, we cannot change the return type of the call
8078 // because there is no place to put the cast instruction (without breaking
8079 // the critical edge). Bail out in this case.
8080 if (!Caller->use_empty())
8081 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
8082 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
8084 if (PHINode *PN = dyn_cast<PHINode>(*UI))
8085 if (PN->getParent() == II->getNormalDest() ||
8086 PN->getParent() == II->getUnwindDest())
8090 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
8091 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
8093 CallSite::arg_iterator AI = CS.arg_begin();
8094 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
8095 const Type *ParamTy = FT->getParamType(i);
8096 const Type *ActTy = (*AI)->getType();
8097 ConstantInt *c = dyn_cast<ConstantInt>(*AI);
8098 //Some conversions are safe even if we do not have a body.
8099 //Either we can cast directly, or we can upconvert the argument
8100 bool isConvertible = ActTy == ParamTy ||
8101 (isa<PointerType>(ParamTy) && isa<PointerType>(ActTy)) ||
8102 (ParamTy->isInteger() && ActTy->isInteger() &&
8103 ParamTy->getPrimitiveSizeInBits() >= ActTy->getPrimitiveSizeInBits()) ||
8104 (c && ParamTy->getPrimitiveSizeInBits() >= ActTy->getPrimitiveSizeInBits()
8105 && c->getValue().isStrictlyPositive());
8106 if (Callee->isDeclaration() && !isConvertible) return false;
8108 // Most other conversions can be done if we have a body, even if these
8109 // lose information, e.g. int->short.
8110 // Some conversions cannot be done at all, e.g. float to pointer.
8111 // Logic here parallels CastInst::getCastOpcode (the design there
8112 // requires legality checks like this be done before calling it).
8113 if (ParamTy->isInteger()) {
8114 if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
8115 if (VActTy->getBitWidth() != ParamTy->getPrimitiveSizeInBits())
8118 if (!ActTy->isInteger() && !ActTy->isFloatingPoint() &&
8119 !isa<PointerType>(ActTy))
8121 } else if (ParamTy->isFloatingPoint()) {
8122 if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
8123 if (VActTy->getBitWidth() != ParamTy->getPrimitiveSizeInBits())
8126 if (!ActTy->isInteger() && !ActTy->isFloatingPoint())
8128 } else if (const VectorType *VParamTy = dyn_cast<VectorType>(ParamTy)) {
8129 if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
8130 if (VActTy->getBitWidth() != VParamTy->getBitWidth())
8133 if (VParamTy->getBitWidth() != ActTy->getPrimitiveSizeInBits())
8135 } else if (isa<PointerType>(ParamTy)) {
8136 if (!ActTy->isInteger() && !isa<PointerType>(ActTy))
8143 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
8144 Callee->isDeclaration())
8145 return false; // Do not delete arguments unless we have a function body...
8147 // Okay, we decided that this is a safe thing to do: go ahead and start
8148 // inserting cast instructions as necessary...
8149 std::vector<Value*> Args;
8150 Args.reserve(NumActualArgs);
8152 AI = CS.arg_begin();
8153 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
8154 const Type *ParamTy = FT->getParamType(i);
8155 if ((*AI)->getType() == ParamTy) {
8156 Args.push_back(*AI);
8158 Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
8159 false, ParamTy, false);
8160 CastInst *NewCast = CastInst::create(opcode, *AI, ParamTy, "tmp");
8161 Args.push_back(InsertNewInstBefore(NewCast, *Caller));
8165 // If the function takes more arguments than the call was taking, add them
8167 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
8168 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
8170 // If we are removing arguments to the function, emit an obnoxious warning...
8171 if (FT->getNumParams() < NumActualArgs)
8172 if (!FT->isVarArg()) {
8173 cerr << "WARNING: While resolving call to function '"
8174 << Callee->getName() << "' arguments were dropped!\n";
8176 // Add all of the arguments in their promoted form to the arg list...
8177 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
8178 const Type *PTy = getPromotedType((*AI)->getType());
8179 if (PTy != (*AI)->getType()) {
8180 // Must promote to pass through va_arg area!
8181 Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, false,
8183 Instruction *Cast = CastInst::create(opcode, *AI, PTy, "tmp");
8184 InsertNewInstBefore(Cast, *Caller);
8185 Args.push_back(Cast);
8187 Args.push_back(*AI);
8192 if (FT->getReturnType() == Type::VoidTy)
8193 Caller->setName(""); // Void type should not have a name.
8196 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
8197 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
8198 Args.begin(), Args.end(), Caller->getName(), Caller);
8199 cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
8200 cast<InvokeInst>(NC)->setParamAttrs(CallerPAL);
8202 NC = new CallInst(Callee, Args.begin(), Args.end(),
8203 Caller->getName(), Caller);
8204 CallInst *CI = cast<CallInst>(Caller);
8205 if (CI->isTailCall())
8206 cast<CallInst>(NC)->setTailCall();
8207 cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
8208 cast<CallInst>(NC)->setParamAttrs(CallerPAL);
8211 // Insert a cast of the return type as necessary.
8213 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
8214 if (NV->getType() != Type::VoidTy) {
8215 const Type *CallerTy = Caller->getType();
8216 Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
8218 NV = NC = CastInst::create(opcode, NC, CallerTy, "tmp");
8220 // If this is an invoke instruction, we should insert it after the first
8221 // non-phi, instruction in the normal successor block.
8222 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
8223 BasicBlock::iterator I = II->getNormalDest()->begin();
8224 while (isa<PHINode>(I)) ++I;
8225 InsertNewInstBefore(NC, *I);
8227 // Otherwise, it's a call, just insert cast right after the call instr
8228 InsertNewInstBefore(NC, *Caller);
8230 AddUsersToWorkList(*Caller);
8232 NV = UndefValue::get(Caller->getType());
8236 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
8237 Caller->replaceAllUsesWith(NV);
8238 Caller->eraseFromParent();
8239 RemoveFromWorkList(Caller);
8243 // transformCallThroughTrampoline - Turn a call to a function created by the
8244 // init_trampoline intrinsic into a direct call to the underlying function.
8246 Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) {
8247 Value *Callee = CS.getCalledValue();
8248 const PointerType *PTy = cast<PointerType>(Callee->getType());
8249 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
8251 IntrinsicInst *Tramp =
8252 cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0));
8255 cast<Function>(IntrinsicInst::StripPointerCasts(Tramp->getOperand(2)));
8256 const PointerType *NestFPTy = cast<PointerType>(NestF->getType());
8257 const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
8259 if (const ParamAttrsList *NestAttrs = NestF->getParamAttrs()) {
8260 unsigned NestIdx = 1;
8261 const Type *NestTy = 0;
8262 uint16_t NestAttr = 0;
8264 // Look for a parameter marked with the 'nest' attribute.
8265 for (FunctionType::param_iterator I = NestFTy->param_begin(),
8266 E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
8267 if (NestAttrs->paramHasAttr(NestIdx, ParamAttr::Nest)) {
8268 // Record the parameter type and any other attributes.
8270 NestAttr = NestAttrs->getParamAttrs(NestIdx);
8275 Instruction *Caller = CS.getInstruction();
8276 std::vector<Value*> NewArgs;
8277 NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
8279 // Insert the nest argument into the call argument list, which may
8280 // mean appending it.
8283 CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
8285 if (Idx == NestIdx) {
8286 // Add the chain argument.
8287 Value *NestVal = Tramp->getOperand(3);
8288 if (NestVal->getType() != NestTy)
8289 NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller);
8290 NewArgs.push_back(NestVal);
8296 // Add the original argument.
8297 NewArgs.push_back(*I);
8303 // The trampoline may have been bitcast to a bogus type (FTy).
8304 // Handle this by synthesizing a new function type, equal to FTy
8305 // with the chain parameter inserted. Likewise for attributes.
8307 const ParamAttrsList *Attrs = CS.getParamAttrs();
8308 std::vector<const Type*> NewTypes;
8309 ParamAttrsVector NewAttrs;
8310 NewTypes.reserve(FTy->getNumParams()+1);
8312 // Add any function result attributes.
8313 uint16_t Attr = Attrs ? Attrs->getParamAttrs(0) : 0;
8315 NewAttrs.push_back (ParamAttrsWithIndex::get(0, Attr));
8317 // Insert the chain's type into the list of parameter types, which may
8318 // mean appending it. Likewise for the chain's attributes.
8321 FunctionType::param_iterator I = FTy->param_begin(),
8322 E = FTy->param_end();
8325 if (Idx == NestIdx) {
8326 // Add the chain's type and attributes.
8327 NewTypes.push_back(NestTy);
8328 NewAttrs.push_back(ParamAttrsWithIndex::get(NestIdx, NestAttr));
8334 // Add the original type and attributes.
8335 NewTypes.push_back(*I);
8336 Attr = Attrs ? Attrs->getParamAttrs(Idx) : 0;
8339 (ParamAttrsWithIndex::get(Idx + (Idx >= NestIdx), Attr));
8345 // Replace the trampoline call with a direct call. Let the generic
8346 // code sort out any function type mismatches.
8347 FunctionType *NewFTy =
8348 FunctionType::get(FTy->getReturnType(), NewTypes, FTy->isVarArg());
8349 Constant *NewCallee = NestF->getType() == PointerType::getUnqual(NewFTy) ?
8350 NestF : ConstantExpr::getBitCast(NestF, PointerType::getUnqual(NewFTy));
8351 const ParamAttrsList *NewPAL = ParamAttrsList::get(NewAttrs);
8353 Instruction *NewCaller;
8354 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
8355 NewCaller = new InvokeInst(NewCallee,
8356 II->getNormalDest(), II->getUnwindDest(),
8357 NewArgs.begin(), NewArgs.end(),
8358 Caller->getName(), Caller);
8359 cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
8360 cast<InvokeInst>(NewCaller)->setParamAttrs(NewPAL);
8362 NewCaller = new CallInst(NewCallee, NewArgs.begin(), NewArgs.end(),
8363 Caller->getName(), Caller);
8364 if (cast<CallInst>(Caller)->isTailCall())
8365 cast<CallInst>(NewCaller)->setTailCall();
8366 cast<CallInst>(NewCaller)->
8367 setCallingConv(cast<CallInst>(Caller)->getCallingConv());
8368 cast<CallInst>(NewCaller)->setParamAttrs(NewPAL);
8370 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
8371 Caller->replaceAllUsesWith(NewCaller);
8372 Caller->eraseFromParent();
8373 RemoveFromWorkList(Caller);
8378 // Replace the trampoline call with a direct call. Since there is no 'nest'
8379 // parameter, there is no need to adjust the argument list. Let the generic
8380 // code sort out any function type mismatches.
8381 Constant *NewCallee =
8382 NestF->getType() == PTy ? NestF : ConstantExpr::getBitCast(NestF, PTy);
8383 CS.setCalledFunction(NewCallee);
8384 return CS.getInstruction();
8387 /// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(c,d)]
8388 /// and if a/b/c/d and the add's all have a single use, turn this into two phi's
8389 /// and a single binop.
8390 Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
8391 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
8392 assert(isa<BinaryOperator>(FirstInst) || isa<GetElementPtrInst>(FirstInst) ||
8393 isa<CmpInst>(FirstInst));
8394 unsigned Opc = FirstInst->getOpcode();
8395 Value *LHSVal = FirstInst->getOperand(0);
8396 Value *RHSVal = FirstInst->getOperand(1);
8398 const Type *LHSType = LHSVal->getType();
8399 const Type *RHSType = RHSVal->getType();
8401 // Scan to see if all operands are the same opcode, all have one use, and all
8402 // kill their operands (i.e. the operands have one use).
8403 for (unsigned i = 0; i != PN.getNumIncomingValues(); ++i) {
8404 Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
8405 if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
8406 // Verify type of the LHS matches so we don't fold cmp's of different
8407 // types or GEP's with different index types.
8408 I->getOperand(0)->getType() != LHSType ||
8409 I->getOperand(1)->getType() != RHSType)
8412 // If they are CmpInst instructions, check their predicates
8413 if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
8414 if (cast<CmpInst>(I)->getPredicate() !=
8415 cast<CmpInst>(FirstInst)->getPredicate())
8418 // Keep track of which operand needs a phi node.
8419 if (I->getOperand(0) != LHSVal) LHSVal = 0;
8420 if (I->getOperand(1) != RHSVal) RHSVal = 0;
8423 // Otherwise, this is safe to transform, determine if it is profitable.
8425 // If this is a GEP, and if the index (not the pointer) needs a PHI, bail out.
8426 // Indexes are often folded into load/store instructions, so we don't want to
8427 // hide them behind a phi.
8428 if (isa<GetElementPtrInst>(FirstInst) && RHSVal == 0)
8431 Value *InLHS = FirstInst->getOperand(0);
8432 Value *InRHS = FirstInst->getOperand(1);
8433 PHINode *NewLHS = 0, *NewRHS = 0;
8435 NewLHS = new PHINode(LHSType, FirstInst->getOperand(0)->getName()+".pn");
8436 NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
8437 NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
8438 InsertNewInstBefore(NewLHS, PN);
8443 NewRHS = new PHINode(RHSType, FirstInst->getOperand(1)->getName()+".pn");
8444 NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
8445 NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
8446 InsertNewInstBefore(NewRHS, PN);
8450 // Add all operands to the new PHIs.
8451 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8453 Value *NewInLHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
8454 NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
8457 Value *NewInRHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(1);
8458 NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
8462 if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
8463 return BinaryOperator::create(BinOp->getOpcode(), LHSVal, RHSVal);
8464 else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
8465 return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(), LHSVal,
8468 assert(isa<GetElementPtrInst>(FirstInst));
8469 return new GetElementPtrInst(LHSVal, RHSVal);
8473 /// isSafeToSinkLoad - Return true if we know that it is safe sink the load out
8474 /// of the block that defines it. This means that it must be obvious the value
8475 /// of the load is not changed from the point of the load to the end of the
8478 /// Finally, it is safe, but not profitable, to sink a load targetting a
8479 /// non-address-taken alloca. Doing so will cause us to not promote the alloca
8481 static bool isSafeToSinkLoad(LoadInst *L) {
8482 BasicBlock::iterator BBI = L, E = L->getParent()->end();
8484 for (++BBI; BBI != E; ++BBI)
8485 if (BBI->mayWriteToMemory())
8488 // Check for non-address taken alloca. If not address-taken already, it isn't
8489 // profitable to do this xform.
8490 if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
8491 bool isAddressTaken = false;
8492 for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
8494 if (isa<LoadInst>(UI)) continue;
8495 if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
8496 // If storing TO the alloca, then the address isn't taken.
8497 if (SI->getOperand(1) == AI) continue;
8499 isAddressTaken = true;
8503 if (!isAddressTaken)
8511 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
8512 // operator and they all are only used by the PHI, PHI together their
8513 // inputs, and do the operation once, to the result of the PHI.
8514 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
8515 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
8517 // Scan the instruction, looking for input operations that can be folded away.
8518 // If all input operands to the phi are the same instruction (e.g. a cast from
8519 // the same type or "+42") we can pull the operation through the PHI, reducing
8520 // code size and simplifying code.
8521 Constant *ConstantOp = 0;
8522 const Type *CastSrcTy = 0;
8523 bool isVolatile = false;
8524 if (isa<CastInst>(FirstInst)) {
8525 CastSrcTy = FirstInst->getOperand(0)->getType();
8526 } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
8527 // Can fold binop, compare or shift here if the RHS is a constant,
8528 // otherwise call FoldPHIArgBinOpIntoPHI.
8529 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
8530 if (ConstantOp == 0)
8531 return FoldPHIArgBinOpIntoPHI(PN);
8532 } else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) {
8533 isVolatile = LI->isVolatile();
8534 // We can't sink the load if the loaded value could be modified between the
8535 // load and the PHI.
8536 if (LI->getParent() != PN.getIncomingBlock(0) ||
8537 !isSafeToSinkLoad(LI))
8539 } else if (isa<GetElementPtrInst>(FirstInst)) {
8540 if (FirstInst->getNumOperands() == 2)
8541 return FoldPHIArgBinOpIntoPHI(PN);
8542 // Can't handle general GEPs yet.
8545 return 0; // Cannot fold this operation.
8548 // Check to see if all arguments are the same operation.
8549 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8550 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
8551 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
8552 if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst))
8555 if (I->getOperand(0)->getType() != CastSrcTy)
8556 return 0; // Cast operation must match.
8557 } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
8558 // We can't sink the load if the loaded value could be modified between
8559 // the load and the PHI.
8560 if (LI->isVolatile() != isVolatile ||
8561 LI->getParent() != PN.getIncomingBlock(i) ||
8562 !isSafeToSinkLoad(LI))
8564 } else if (I->getOperand(1) != ConstantOp) {
8569 // Okay, they are all the same operation. Create a new PHI node of the
8570 // correct type, and PHI together all of the LHS's of the instructions.
8571 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
8572 PN.getName()+".in");
8573 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
8575 Value *InVal = FirstInst->getOperand(0);
8576 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
8578 // Add all operands to the new PHI.
8579 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8580 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
8581 if (NewInVal != InVal)
8583 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
8588 // The new PHI unions all of the same values together. This is really
8589 // common, so we handle it intelligently here for compile-time speed.
8593 InsertNewInstBefore(NewPN, PN);
8597 // Insert and return the new operation.
8598 if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
8599 return CastInst::create(FirstCI->getOpcode(), PhiVal, PN.getType());
8600 else if (isa<LoadInst>(FirstInst))
8601 return new LoadInst(PhiVal, "", isVolatile);
8602 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
8603 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
8604 else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
8605 return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(),
8606 PhiVal, ConstantOp);
8608 assert(0 && "Unknown operation");
8612 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
8614 static bool DeadPHICycle(PHINode *PN,
8615 SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
8616 if (PN->use_empty()) return true;
8617 if (!PN->hasOneUse()) return false;
8619 // Remember this node, and if we find the cycle, return.
8620 if (!PotentiallyDeadPHIs.insert(PN))
8623 // Don't scan crazily complex things.
8624 if (PotentiallyDeadPHIs.size() == 16)
8627 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
8628 return DeadPHICycle(PU, PotentiallyDeadPHIs);
8633 /// PHIsEqualValue - Return true if this phi node is always equal to
8634 /// NonPhiInVal. This happens with mutually cyclic phi nodes like:
8635 /// z = some value; x = phi (y, z); y = phi (x, z)
8636 static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
8637 SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
8638 // See if we already saw this PHI node.
8639 if (!ValueEqualPHIs.insert(PN))
8642 // Don't scan crazily complex things.
8643 if (ValueEqualPHIs.size() == 16)
8646 // Scan the operands to see if they are either phi nodes or are equal to
8648 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
8649 Value *Op = PN->getIncomingValue(i);
8650 if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
8651 if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
8653 } else if (Op != NonPhiInVal)
8661 // PHINode simplification
8663 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
8664 // If LCSSA is around, don't mess with Phi nodes
8665 if (MustPreserveLCSSA) return 0;
8667 if (Value *V = PN.hasConstantValue())
8668 return ReplaceInstUsesWith(PN, V);
8670 // If all PHI operands are the same operation, pull them through the PHI,
8671 // reducing code size.
8672 if (isa<Instruction>(PN.getIncomingValue(0)) &&
8673 PN.getIncomingValue(0)->hasOneUse())
8674 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
8677 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
8678 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
8679 // PHI)... break the cycle.
8680 if (PN.hasOneUse()) {
8681 Instruction *PHIUser = cast<Instruction>(PN.use_back());
8682 if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
8683 SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
8684 PotentiallyDeadPHIs.insert(&PN);
8685 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
8686 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
8689 // If this phi has a single use, and if that use just computes a value for
8690 // the next iteration of a loop, delete the phi. This occurs with unused
8691 // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
8692 // common case here is good because the only other things that catch this
8693 // are induction variable analysis (sometimes) and ADCE, which is only run
8695 if (PHIUser->hasOneUse() &&
8696 (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
8697 PHIUser->use_back() == &PN) {
8698 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
8702 // We sometimes end up with phi cycles that non-obviously end up being the
8703 // same value, for example:
8704 // z = some value; x = phi (y, z); y = phi (x, z)
8705 // where the phi nodes don't necessarily need to be in the same block. Do a
8706 // quick check to see if the PHI node only contains a single non-phi value, if
8707 // so, scan to see if the phi cycle is actually equal to that value.
8709 unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues();
8710 // Scan for the first non-phi operand.
8711 while (InValNo != NumOperandVals &&
8712 isa<PHINode>(PN.getIncomingValue(InValNo)))
8715 if (InValNo != NumOperandVals) {
8716 Value *NonPhiInVal = PN.getOperand(InValNo);
8718 // Scan the rest of the operands to see if there are any conflicts, if so
8719 // there is no need to recursively scan other phis.
8720 for (++InValNo; InValNo != NumOperandVals; ++InValNo) {
8721 Value *OpVal = PN.getIncomingValue(InValNo);
8722 if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
8726 // If we scanned over all operands, then we have one unique value plus
8727 // phi values. Scan PHI nodes to see if they all merge in each other or
8729 if (InValNo == NumOperandVals) {
8730 SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
8731 if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
8732 return ReplaceInstUsesWith(PN, NonPhiInVal);
8739 static Value *InsertCastToIntPtrTy(Value *V, const Type *DTy,
8740 Instruction *InsertPoint,
8742 unsigned PtrSize = DTy->getPrimitiveSizeInBits();
8743 unsigned VTySize = V->getType()->getPrimitiveSizeInBits();
8744 // We must cast correctly to the pointer type. Ensure that we
8745 // sign extend the integer value if it is smaller as this is
8746 // used for address computation.
8747 Instruction::CastOps opcode =
8748 (VTySize < PtrSize ? Instruction::SExt :
8749 (VTySize == PtrSize ? Instruction::BitCast : Instruction::Trunc));
8750 return IC->InsertCastBefore(opcode, V, DTy, *InsertPoint);
8754 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
8755 Value *PtrOp = GEP.getOperand(0);
8756 // Is it 'getelementptr %P, i32 0' or 'getelementptr %P'
8757 // If so, eliminate the noop.
8758 if (GEP.getNumOperands() == 1)
8759 return ReplaceInstUsesWith(GEP, PtrOp);
8761 if (isa<UndefValue>(GEP.getOperand(0)))
8762 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
8764 bool HasZeroPointerIndex = false;
8765 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
8766 HasZeroPointerIndex = C->isNullValue();
8768 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
8769 return ReplaceInstUsesWith(GEP, PtrOp);
8771 // Eliminate unneeded casts for indices.
8772 bool MadeChange = false;
8774 gep_type_iterator GTI = gep_type_begin(GEP);
8775 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI) {
8776 if (isa<SequentialType>(*GTI)) {
8777 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
8778 if (CI->getOpcode() == Instruction::ZExt ||
8779 CI->getOpcode() == Instruction::SExt) {
8780 const Type *SrcTy = CI->getOperand(0)->getType();
8781 // We can eliminate a cast from i32 to i64 iff the target
8782 // is a 32-bit pointer target.
8783 if (SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
8785 GEP.setOperand(i, CI->getOperand(0));
8789 // If we are using a wider index than needed for this platform, shrink it
8790 // to what we need. If the incoming value needs a cast instruction,
8791 // insert it. This explicit cast can make subsequent optimizations more
8793 Value *Op = GEP.getOperand(i);
8794 if (TD->getTypeSizeInBits(Op->getType()) > TD->getPointerSizeInBits())
8795 if (Constant *C = dyn_cast<Constant>(Op)) {
8796 GEP.setOperand(i, ConstantExpr::getTrunc(C, TD->getIntPtrType()));
8799 Op = InsertCastBefore(Instruction::Trunc, Op, TD->getIntPtrType(),
8801 GEP.setOperand(i, Op);
8806 if (MadeChange) return &GEP;
8808 // If this GEP instruction doesn't move the pointer, and if the input operand
8809 // is a bitcast of another pointer, just replace the GEP with a bitcast of the
8810 // real input to the dest type.
8811 if (GEP.hasAllZeroIndices()) {
8812 if (BitCastInst *BCI = dyn_cast<BitCastInst>(GEP.getOperand(0))) {
8813 // If the bitcast is of an allocation, and the allocation will be
8814 // converted to match the type of the cast, don't touch this.
8815 if (isa<AllocationInst>(BCI->getOperand(0))) {
8816 // See if the bitcast simplifies, if so, don't nuke this GEP yet.
8817 if (Instruction *I = visitBitCast(*BCI)) {
8820 BCI->getParent()->getInstList().insert(BCI, I);
8821 ReplaceInstUsesWith(*BCI, I);
8826 return new BitCastInst(BCI->getOperand(0), GEP.getType());
8830 // Combine Indices - If the source pointer to this getelementptr instruction
8831 // is a getelementptr instruction, combine the indices of the two
8832 // getelementptr instructions into a single instruction.
8834 SmallVector<Value*, 8> SrcGEPOperands;
8835 if (User *Src = dyn_castGetElementPtr(PtrOp))
8836 SrcGEPOperands.append(Src->op_begin(), Src->op_end());
8838 if (!SrcGEPOperands.empty()) {
8839 // Note that if our source is a gep chain itself that we wait for that
8840 // chain to be resolved before we perform this transformation. This
8841 // avoids us creating a TON of code in some cases.
8843 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
8844 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
8845 return 0; // Wait until our source is folded to completion.
8847 SmallVector<Value*, 8> Indices;
8849 // Find out whether the last index in the source GEP is a sequential idx.
8850 bool EndsWithSequential = false;
8851 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
8852 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
8853 EndsWithSequential = !isa<StructType>(*I);
8855 // Can we combine the two pointer arithmetics offsets?
8856 if (EndsWithSequential) {
8857 // Replace: gep (gep %P, long B), long A, ...
8858 // With: T = long A+B; gep %P, T, ...
8860 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
8861 if (SO1 == Constant::getNullValue(SO1->getType())) {
8863 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
8866 // If they aren't the same type, convert both to an integer of the
8867 // target's pointer size.
8868 if (SO1->getType() != GO1->getType()) {
8869 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
8870 SO1 = ConstantExpr::getIntegerCast(SO1C, GO1->getType(), true);
8871 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
8872 GO1 = ConstantExpr::getIntegerCast(GO1C, SO1->getType(), true);
8874 unsigned PS = TD->getPointerSizeInBits();
8875 if (TD->getTypeSizeInBits(SO1->getType()) == PS) {
8876 // Convert GO1 to SO1's type.
8877 GO1 = InsertCastToIntPtrTy(GO1, SO1->getType(), &GEP, this);
8879 } else if (TD->getTypeSizeInBits(GO1->getType()) == PS) {
8880 // Convert SO1 to GO1's type.
8881 SO1 = InsertCastToIntPtrTy(SO1, GO1->getType(), &GEP, this);
8883 const Type *PT = TD->getIntPtrType();
8884 SO1 = InsertCastToIntPtrTy(SO1, PT, &GEP, this);
8885 GO1 = InsertCastToIntPtrTy(GO1, PT, &GEP, this);
8889 if (isa<Constant>(SO1) && isa<Constant>(GO1))
8890 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
8892 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
8893 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
8897 // Recycle the GEP we already have if possible.
8898 if (SrcGEPOperands.size() == 2) {
8899 GEP.setOperand(0, SrcGEPOperands[0]);
8900 GEP.setOperand(1, Sum);
8903 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
8904 SrcGEPOperands.end()-1);
8905 Indices.push_back(Sum);
8906 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
8908 } else if (isa<Constant>(*GEP.idx_begin()) &&
8909 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
8910 SrcGEPOperands.size() != 1) {
8911 // Otherwise we can do the fold if the first index of the GEP is a zero
8912 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
8913 SrcGEPOperands.end());
8914 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
8917 if (!Indices.empty())
8918 return new GetElementPtrInst(SrcGEPOperands[0], Indices.begin(),
8919 Indices.end(), GEP.getName());
8921 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
8922 // GEP of global variable. If all of the indices for this GEP are
8923 // constants, we can promote this to a constexpr instead of an instruction.
8925 // Scan for nonconstants...
8926 SmallVector<Constant*, 8> Indices;
8927 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
8928 for (; I != E && isa<Constant>(*I); ++I)
8929 Indices.push_back(cast<Constant>(*I));
8931 if (I == E) { // If they are all constants...
8932 Constant *CE = ConstantExpr::getGetElementPtr(GV,
8933 &Indices[0],Indices.size());
8935 // Replace all uses of the GEP with the new constexpr...
8936 return ReplaceInstUsesWith(GEP, CE);
8938 } else if (Value *X = getBitCastOperand(PtrOp)) { // Is the operand a cast?
8939 if (!isa<PointerType>(X->getType())) {
8940 // Not interesting. Source pointer must be a cast from pointer.
8941 } else if (HasZeroPointerIndex) {
8942 // transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
8943 // into : GEP [10 x i8]* X, i32 0, ...
8945 // This occurs when the program declares an array extern like "int X[];"
8947 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
8948 const PointerType *XTy = cast<PointerType>(X->getType());
8949 if (const ArrayType *XATy =
8950 dyn_cast<ArrayType>(XTy->getElementType()))
8951 if (const ArrayType *CATy =
8952 dyn_cast<ArrayType>(CPTy->getElementType()))
8953 if (CATy->getElementType() == XATy->getElementType()) {
8954 // At this point, we know that the cast source type is a pointer
8955 // to an array of the same type as the destination pointer
8956 // array. Because the array type is never stepped over (there
8957 // is a leading zero) we can fold the cast into this GEP.
8958 GEP.setOperand(0, X);
8961 } else if (GEP.getNumOperands() == 2) {
8962 // Transform things like:
8963 // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
8964 // into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
8965 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
8966 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
8967 if (isa<ArrayType>(SrcElTy) &&
8968 TD->getABITypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
8969 TD->getABITypeSize(ResElTy)) {
8971 Idx[0] = Constant::getNullValue(Type::Int32Ty);
8972 Idx[1] = GEP.getOperand(1);
8973 Value *V = InsertNewInstBefore(
8974 new GetElementPtrInst(X, Idx, Idx + 2, GEP.getName()), GEP);
8975 // V and GEP are both pointer types --> BitCast
8976 return new BitCastInst(V, GEP.getType());
8979 // Transform things like:
8980 // getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
8981 // (where tmp = 8*tmp2) into:
8982 // getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
8984 if (isa<ArrayType>(SrcElTy) && ResElTy == Type::Int8Ty) {
8985 uint64_t ArrayEltSize =
8986 TD->getABITypeSize(cast<ArrayType>(SrcElTy)->getElementType());
8988 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
8989 // allow either a mul, shift, or constant here.
8991 ConstantInt *Scale = 0;
8992 if (ArrayEltSize == 1) {
8993 NewIdx = GEP.getOperand(1);
8994 Scale = ConstantInt::get(NewIdx->getType(), 1);
8995 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
8996 NewIdx = ConstantInt::get(CI->getType(), 1);
8998 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
8999 if (Inst->getOpcode() == Instruction::Shl &&
9000 isa<ConstantInt>(Inst->getOperand(1))) {
9001 ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
9002 uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
9003 Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmtVal);
9004 NewIdx = Inst->getOperand(0);
9005 } else if (Inst->getOpcode() == Instruction::Mul &&
9006 isa<ConstantInt>(Inst->getOperand(1))) {
9007 Scale = cast<ConstantInt>(Inst->getOperand(1));
9008 NewIdx = Inst->getOperand(0);
9012 // If the index will be to exactly the right offset with the scale taken
9013 // out, perform the transformation. Note, we don't know whether Scale is
9014 // signed or not. We'll use unsigned version of division/modulo
9015 // operation after making sure Scale doesn't have the sign bit set.
9016 if (Scale && Scale->getSExtValue() >= 0LL &&
9017 Scale->getZExtValue() % ArrayEltSize == 0) {
9018 Scale = ConstantInt::get(Scale->getType(),
9019 Scale->getZExtValue() / ArrayEltSize);
9020 if (Scale->getZExtValue() != 1) {
9021 Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
9023 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
9024 NewIdx = InsertNewInstBefore(Sc, GEP);
9027 // Insert the new GEP instruction.
9029 Idx[0] = Constant::getNullValue(Type::Int32Ty);
9031 Instruction *NewGEP =
9032 new GetElementPtrInst(X, Idx, Idx + 2, GEP.getName());
9033 NewGEP = InsertNewInstBefore(NewGEP, GEP);
9034 // The NewGEP must be pointer typed, so must the old one -> BitCast
9035 return new BitCastInst(NewGEP, GEP.getType());
9044 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
9045 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
9046 if (AI.isArrayAllocation()) // Check C != 1
9047 if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
9049 ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
9050 AllocationInst *New = 0;
9052 // Create and insert the replacement instruction...
9053 if (isa<MallocInst>(AI))
9054 New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
9056 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
9057 New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
9060 InsertNewInstBefore(New, AI);
9062 // Scan to the end of the allocation instructions, to skip over a block of
9063 // allocas if possible...
9065 BasicBlock::iterator It = New;
9066 while (isa<AllocationInst>(*It)) ++It;
9068 // Now that I is pointing to the first non-allocation-inst in the block,
9069 // insert our getelementptr instruction...
9071 Value *NullIdx = Constant::getNullValue(Type::Int32Ty);
9075 Value *V = new GetElementPtrInst(New, Idx, Idx + 2,
9076 New->getName()+".sub", It);
9078 // Now make everything use the getelementptr instead of the original
9080 return ReplaceInstUsesWith(AI, V);
9081 } else if (isa<UndefValue>(AI.getArraySize())) {
9082 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
9085 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
9086 // Note that we only do this for alloca's, because malloc should allocate and
9087 // return a unique pointer, even for a zero byte allocation.
9088 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
9089 TD->getABITypeSize(AI.getAllocatedType()) == 0)
9090 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
9095 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
9096 Value *Op = FI.getOperand(0);
9098 // free undef -> unreachable.
9099 if (isa<UndefValue>(Op)) {
9100 // Insert a new store to null because we cannot modify the CFG here.
9101 new StoreInst(ConstantInt::getTrue(),
9102 UndefValue::get(PointerType::getUnqual(Type::Int1Ty)), &FI);
9103 return EraseInstFromFunction(FI);
9106 // If we have 'free null' delete the instruction. This can happen in stl code
9107 // when lots of inlining happens.
9108 if (isa<ConstantPointerNull>(Op))
9109 return EraseInstFromFunction(FI);
9111 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
9112 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op)) {
9113 FI.setOperand(0, CI->getOperand(0));
9117 // Change free (gep X, 0,0,0,0) into free(X)
9118 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
9119 if (GEPI->hasAllZeroIndices()) {
9120 AddToWorkList(GEPI);
9121 FI.setOperand(0, GEPI->getOperand(0));
9126 // Change free(malloc) into nothing, if the malloc has a single use.
9127 if (MallocInst *MI = dyn_cast<MallocInst>(Op))
9128 if (MI->hasOneUse()) {
9129 EraseInstFromFunction(FI);
9130 return EraseInstFromFunction(*MI);
9137 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
9138 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
9139 const TargetData *TD) {
9140 User *CI = cast<User>(LI.getOperand(0));
9141 Value *CastOp = CI->getOperand(0);
9143 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(CI)) {
9144 // Instead of loading constant c string, use corresponding integer value
9145 // directly if string length is small enough.
9146 const std::string &Str = CE->getOperand(0)->getStringValue();
9148 unsigned len = Str.length();
9149 const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
9150 unsigned numBits = Ty->getPrimitiveSizeInBits();
9151 // Replace LI with immediate integer store.
9152 if ((numBits >> 3) == len + 1) {
9153 APInt StrVal(numBits, 0);
9154 APInt SingleChar(numBits, 0);
9155 if (TD->isLittleEndian()) {
9156 for (signed i = len-1; i >= 0; i--) {
9157 SingleChar = (uint64_t) Str[i];
9158 StrVal = (StrVal << 8) | SingleChar;
9161 for (unsigned i = 0; i < len; i++) {
9162 SingleChar = (uint64_t) Str[i];
9163 StrVal = (StrVal << 8) | SingleChar;
9165 // Append NULL at the end.
9167 StrVal = (StrVal << 8) | SingleChar;
9169 Value *NL = ConstantInt::get(StrVal);
9170 return IC.ReplaceInstUsesWith(LI, NL);
9175 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
9176 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
9177 const Type *SrcPTy = SrcTy->getElementType();
9179 if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
9180 isa<VectorType>(DestPTy)) {
9181 // If the source is an array, the code below will not succeed. Check to
9182 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
9184 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
9185 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
9186 if (ASrcTy->getNumElements() != 0) {
9188 Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
9189 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
9190 SrcTy = cast<PointerType>(CastOp->getType());
9191 SrcPTy = SrcTy->getElementType();
9194 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
9195 isa<VectorType>(SrcPTy)) &&
9196 // Do not allow turning this into a load of an integer, which is then
9197 // casted to a pointer, this pessimizes pointer analysis a lot.
9198 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
9199 IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
9200 IC.getTargetData().getTypeSizeInBits(DestPTy)) {
9202 // Okay, we are casting from one integer or pointer type to another of
9203 // the same size. Instead of casting the pointer before the load, cast
9204 // the result of the loaded value.
9205 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
9207 LI.isVolatile()),LI);
9208 // Now cast the result of the load.
9209 return new BitCastInst(NewLoad, LI.getType());
9216 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
9217 /// from this value cannot trap. If it is not obviously safe to load from the
9218 /// specified pointer, we do a quick local scan of the basic block containing
9219 /// ScanFrom, to determine if the address is already accessed.
9220 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
9221 // If it is an alloca it is always safe to load from.
9222 if (isa<AllocaInst>(V)) return true;
9224 // If it is a global variable it is mostly safe to load from.
9225 if (const GlobalValue *GV = dyn_cast<GlobalVariable>(V))
9226 // Don't try to evaluate aliases. External weak GV can be null.
9227 return !isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage();
9229 // Otherwise, be a little bit agressive by scanning the local block where we
9230 // want to check to see if the pointer is already being loaded or stored
9231 // from/to. If so, the previous load or store would have already trapped,
9232 // so there is no harm doing an extra load (also, CSE will later eliminate
9233 // the load entirely).
9234 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
9239 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
9240 if (LI->getOperand(0) == V) return true;
9241 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
9242 if (SI->getOperand(1) == V) return true;
9248 /// GetUnderlyingObject - Trace through a series of getelementptrs and bitcasts
9249 /// until we find the underlying object a pointer is referring to or something
9250 /// we don't understand. Note that the returned pointer may be offset from the
9251 /// input, because we ignore GEP indices.
9252 static Value *GetUnderlyingObject(Value *Ptr) {
9254 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) {
9255 if (CE->getOpcode() == Instruction::BitCast ||
9256 CE->getOpcode() == Instruction::GetElementPtr)
9257 Ptr = CE->getOperand(0);
9260 } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(Ptr)) {
9261 Ptr = BCI->getOperand(0);
9262 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
9263 Ptr = GEP->getOperand(0);
9270 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
9271 Value *Op = LI.getOperand(0);
9273 // Attempt to improve the alignment.
9274 unsigned KnownAlign = GetOrEnforceKnownAlignment(Op, TD);
9275 if (KnownAlign > LI.getAlignment())
9276 LI.setAlignment(KnownAlign);
9278 // load (cast X) --> cast (load X) iff safe
9279 if (isa<CastInst>(Op))
9280 if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
9283 // None of the following transforms are legal for volatile loads.
9284 if (LI.isVolatile()) return 0;
9286 if (&LI.getParent()->front() != &LI) {
9287 BasicBlock::iterator BBI = &LI; --BBI;
9288 // If the instruction immediately before this is a store to the same
9289 // address, do a simple form of store->load forwarding.
9290 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
9291 if (SI->getOperand(1) == LI.getOperand(0))
9292 return ReplaceInstUsesWith(LI, SI->getOperand(0));
9293 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
9294 if (LIB->getOperand(0) == LI.getOperand(0))
9295 return ReplaceInstUsesWith(LI, LIB);
9298 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
9299 if (isa<ConstantPointerNull>(GEPI->getOperand(0))) {
9300 // Insert a new store to null instruction before the load to indicate
9301 // that this code is not reachable. We do this instead of inserting
9302 // an unreachable instruction directly because we cannot modify the
9304 new StoreInst(UndefValue::get(LI.getType()),
9305 Constant::getNullValue(Op->getType()), &LI);
9306 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9309 if (Constant *C = dyn_cast<Constant>(Op)) {
9310 // load null/undef -> undef
9311 if ((C->isNullValue() || isa<UndefValue>(C))) {
9312 // Insert a new store to null instruction before the load to indicate that
9313 // this code is not reachable. We do this instead of inserting an
9314 // unreachable instruction directly because we cannot modify the CFG.
9315 new StoreInst(UndefValue::get(LI.getType()),
9316 Constant::getNullValue(Op->getType()), &LI);
9317 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9320 // Instcombine load (constant global) into the value loaded.
9321 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
9322 if (GV->isConstant() && !GV->isDeclaration())
9323 return ReplaceInstUsesWith(LI, GV->getInitializer());
9325 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
9326 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
9327 if (CE->getOpcode() == Instruction::GetElementPtr) {
9328 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
9329 if (GV->isConstant() && !GV->isDeclaration())
9331 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
9332 return ReplaceInstUsesWith(LI, V);
9333 if (CE->getOperand(0)->isNullValue()) {
9334 // Insert a new store to null instruction before the load to indicate
9335 // that this code is not reachable. We do this instead of inserting
9336 // an unreachable instruction directly because we cannot modify the
9338 new StoreInst(UndefValue::get(LI.getType()),
9339 Constant::getNullValue(Op->getType()), &LI);
9340 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9343 } else if (CE->isCast()) {
9344 if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
9349 // If this load comes from anywhere in a constant global, and if the global
9350 // is all undef or zero, we know what it loads.
9351 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(Op))) {
9352 if (GV->isConstant() && GV->hasInitializer()) {
9353 if (GV->getInitializer()->isNullValue())
9354 return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
9355 else if (isa<UndefValue>(GV->getInitializer()))
9356 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9360 if (Op->hasOneUse()) {
9361 // Change select and PHI nodes to select values instead of addresses: this
9362 // helps alias analysis out a lot, allows many others simplifications, and
9363 // exposes redundancy in the code.
9365 // Note that we cannot do the transformation unless we know that the
9366 // introduced loads cannot trap! Something like this is valid as long as
9367 // the condition is always false: load (select bool %C, int* null, int* %G),
9368 // but it would not be valid if we transformed it to load from null
9371 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
9372 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
9373 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
9374 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
9375 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
9376 SI->getOperand(1)->getName()+".val"), LI);
9377 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
9378 SI->getOperand(2)->getName()+".val"), LI);
9379 return new SelectInst(SI->getCondition(), V1, V2);
9382 // load (select (cond, null, P)) -> load P
9383 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
9384 if (C->isNullValue()) {
9385 LI.setOperand(0, SI->getOperand(2));
9389 // load (select (cond, P, null)) -> load P
9390 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
9391 if (C->isNullValue()) {
9392 LI.setOperand(0, SI->getOperand(1));
9400 /// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
9402 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
9403 User *CI = cast<User>(SI.getOperand(1));
9404 Value *CastOp = CI->getOperand(0);
9406 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
9407 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
9408 const Type *SrcPTy = SrcTy->getElementType();
9410 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
9411 // If the source is an array, the code below will not succeed. Check to
9412 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
9414 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
9415 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
9416 if (ASrcTy->getNumElements() != 0) {
9418 Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
9419 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
9420 SrcTy = cast<PointerType>(CastOp->getType());
9421 SrcPTy = SrcTy->getElementType();
9424 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
9425 IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
9426 IC.getTargetData().getTypeSizeInBits(DestPTy)) {
9428 // Okay, we are casting from one integer or pointer type to another of
9429 // the same size. Instead of casting the pointer before
9430 // the store, cast the value to be stored.
9432 Value *SIOp0 = SI.getOperand(0);
9433 Instruction::CastOps opcode = Instruction::BitCast;
9434 const Type* CastSrcTy = SIOp0->getType();
9435 const Type* CastDstTy = SrcPTy;
9436 if (isa<PointerType>(CastDstTy)) {
9437 if (CastSrcTy->isInteger())
9438 opcode = Instruction::IntToPtr;
9439 } else if (isa<IntegerType>(CastDstTy)) {
9440 if (isa<PointerType>(SIOp0->getType()))
9441 opcode = Instruction::PtrToInt;
9443 if (Constant *C = dyn_cast<Constant>(SIOp0))
9444 NewCast = ConstantExpr::getCast(opcode, C, CastDstTy);
9446 NewCast = IC.InsertNewInstBefore(
9447 CastInst::create(opcode, SIOp0, CastDstTy, SIOp0->getName()+".c"),
9449 return new StoreInst(NewCast, CastOp);
9456 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
9457 Value *Val = SI.getOperand(0);
9458 Value *Ptr = SI.getOperand(1);
9460 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
9461 EraseInstFromFunction(SI);
9466 // If the RHS is an alloca with a single use, zapify the store, making the
9468 if (Ptr->hasOneUse()) {
9469 if (isa<AllocaInst>(Ptr)) {
9470 EraseInstFromFunction(SI);
9475 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
9476 if (isa<AllocaInst>(GEP->getOperand(0)) &&
9477 GEP->getOperand(0)->hasOneUse()) {
9478 EraseInstFromFunction(SI);
9484 // Attempt to improve the alignment.
9485 unsigned KnownAlign = GetOrEnforceKnownAlignment(Ptr, TD);
9486 if (KnownAlign > SI.getAlignment())
9487 SI.setAlignment(KnownAlign);
9489 // Do really simple DSE, to catch cases where there are several consequtive
9490 // stores to the same location, separated by a few arithmetic operations. This
9491 // situation often occurs with bitfield accesses.
9492 BasicBlock::iterator BBI = &SI;
9493 for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
9497 if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
9498 // Prev store isn't volatile, and stores to the same location?
9499 if (!PrevSI->isVolatile() && PrevSI->getOperand(1) == SI.getOperand(1)) {
9502 EraseInstFromFunction(*PrevSI);
9508 // If this is a load, we have to stop. However, if the loaded value is from
9509 // the pointer we're loading and is producing the pointer we're storing,
9510 // then *this* store is dead (X = load P; store X -> P).
9511 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
9512 if (LI == Val && LI->getOperand(0) == Ptr && !SI.isVolatile()) {
9513 EraseInstFromFunction(SI);
9517 // Otherwise, this is a load from some other location. Stores before it
9522 // Don't skip over loads or things that can modify memory.
9523 if (BBI->mayWriteToMemory())
9528 if (SI.isVolatile()) return 0; // Don't hack volatile stores.
9530 // store X, null -> turns into 'unreachable' in SimplifyCFG
9531 if (isa<ConstantPointerNull>(Ptr)) {
9532 if (!isa<UndefValue>(Val)) {
9533 SI.setOperand(0, UndefValue::get(Val->getType()));
9534 if (Instruction *U = dyn_cast<Instruction>(Val))
9535 AddToWorkList(U); // Dropped a use.
9538 return 0; // Do not modify these!
9541 // store undef, Ptr -> noop
9542 if (isa<UndefValue>(Val)) {
9543 EraseInstFromFunction(SI);
9548 // If the pointer destination is a cast, see if we can fold the cast into the
9550 if (isa<CastInst>(Ptr))
9551 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
9553 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
9555 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
9559 // If this store is the last instruction in the basic block, and if the block
9560 // ends with an unconditional branch, try to move it to the successor block.
9562 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
9563 if (BI->isUnconditional())
9564 if (SimplifyStoreAtEndOfBlock(SI))
9565 return 0; // xform done!
9570 /// SimplifyStoreAtEndOfBlock - Turn things like:
9571 /// if () { *P = v1; } else { *P = v2 }
9572 /// into a phi node with a store in the successor.
9574 /// Simplify things like:
9575 /// *P = v1; if () { *P = v2; }
9576 /// into a phi node with a store in the successor.
9578 bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
9579 BasicBlock *StoreBB = SI.getParent();
9581 // Check to see if the successor block has exactly two incoming edges. If
9582 // so, see if the other predecessor contains a store to the same location.
9583 // if so, insert a PHI node (if needed) and move the stores down.
9584 BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
9586 // Determine whether Dest has exactly two predecessors and, if so, compute
9587 // the other predecessor.
9588 pred_iterator PI = pred_begin(DestBB);
9589 BasicBlock *OtherBB = 0;
9593 if (PI == pred_end(DestBB))
9596 if (*PI != StoreBB) {
9601 if (++PI != pred_end(DestBB))
9605 // Verify that the other block ends in a branch and is not otherwise empty.
9606 BasicBlock::iterator BBI = OtherBB->getTerminator();
9607 BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
9608 if (!OtherBr || BBI == OtherBB->begin())
9611 // If the other block ends in an unconditional branch, check for the 'if then
9612 // else' case. there is an instruction before the branch.
9613 StoreInst *OtherStore = 0;
9614 if (OtherBr->isUnconditional()) {
9615 // If this isn't a store, or isn't a store to the same location, bail out.
9617 OtherStore = dyn_cast<StoreInst>(BBI);
9618 if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1))
9621 // Otherwise, the other block ended with a conditional branch. If one of the
9622 // destinations is StoreBB, then we have the if/then case.
9623 if (OtherBr->getSuccessor(0) != StoreBB &&
9624 OtherBr->getSuccessor(1) != StoreBB)
9627 // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
9628 // if/then triangle. See if there is a store to the same ptr as SI that
9629 // lives in OtherBB.
9631 // Check to see if we find the matching store.
9632 if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
9633 if (OtherStore->getOperand(1) != SI.getOperand(1))
9637 // If we find something that may be using the stored value, or if we run
9638 // out of instructions, we can't do the xform.
9639 if (isa<LoadInst>(BBI) || BBI->mayWriteToMemory() ||
9640 BBI == OtherBB->begin())
9644 // In order to eliminate the store in OtherBr, we have to
9645 // make sure nothing reads the stored value in StoreBB.
9646 for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
9647 // FIXME: This should really be AA driven.
9648 if (isa<LoadInst>(I) || I->mayWriteToMemory())
9653 // Insert a PHI node now if we need it.
9654 Value *MergedVal = OtherStore->getOperand(0);
9655 if (MergedVal != SI.getOperand(0)) {
9656 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
9657 PN->reserveOperandSpace(2);
9658 PN->addIncoming(SI.getOperand(0), SI.getParent());
9659 PN->addIncoming(OtherStore->getOperand(0), OtherBB);
9660 MergedVal = InsertNewInstBefore(PN, DestBB->front());
9663 // Advance to a place where it is safe to insert the new store and
9665 BBI = DestBB->begin();
9666 while (isa<PHINode>(BBI)) ++BBI;
9667 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
9668 OtherStore->isVolatile()), *BBI);
9670 // Nuke the old stores.
9671 EraseInstFromFunction(SI);
9672 EraseInstFromFunction(*OtherStore);
9678 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
9679 // Change br (not X), label True, label False to: br X, label False, True
9681 BasicBlock *TrueDest;
9682 BasicBlock *FalseDest;
9683 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
9684 !isa<Constant>(X)) {
9685 // Swap Destinations and condition...
9687 BI.setSuccessor(0, FalseDest);
9688 BI.setSuccessor(1, TrueDest);
9692 // Cannonicalize fcmp_one -> fcmp_oeq
9693 FCmpInst::Predicate FPred; Value *Y;
9694 if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
9695 TrueDest, FalseDest)))
9696 if ((FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
9697 FPred == FCmpInst::FCMP_OGE) && BI.getCondition()->hasOneUse()) {
9698 FCmpInst *I = cast<FCmpInst>(BI.getCondition());
9699 FCmpInst::Predicate NewPred = FCmpInst::getInversePredicate(FPred);
9700 Instruction *NewSCC = new FCmpInst(NewPred, X, Y, "", I);
9701 NewSCC->takeName(I);
9702 // Swap Destinations and condition...
9703 BI.setCondition(NewSCC);
9704 BI.setSuccessor(0, FalseDest);
9705 BI.setSuccessor(1, TrueDest);
9706 RemoveFromWorkList(I);
9707 I->eraseFromParent();
9708 AddToWorkList(NewSCC);
9712 // Cannonicalize icmp_ne -> icmp_eq
9713 ICmpInst::Predicate IPred;
9714 if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
9715 TrueDest, FalseDest)))
9716 if ((IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
9717 IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
9718 IPred == ICmpInst::ICMP_SGE) && BI.getCondition()->hasOneUse()) {
9719 ICmpInst *I = cast<ICmpInst>(BI.getCondition());
9720 ICmpInst::Predicate NewPred = ICmpInst::getInversePredicate(IPred);
9721 Instruction *NewSCC = new ICmpInst(NewPred, X, Y, "", I);
9722 NewSCC->takeName(I);
9723 // Swap Destinations and condition...
9724 BI.setCondition(NewSCC);
9725 BI.setSuccessor(0, FalseDest);
9726 BI.setSuccessor(1, TrueDest);
9727 RemoveFromWorkList(I);
9728 I->eraseFromParent();;
9729 AddToWorkList(NewSCC);
9736 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
9737 Value *Cond = SI.getCondition();
9738 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
9739 if (I->getOpcode() == Instruction::Add)
9740 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
9741 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
9742 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
9743 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
9745 SI.setOperand(0, I->getOperand(0));
9753 /// CheapToScalarize - Return true if the value is cheaper to scalarize than it
9754 /// is to leave as a vector operation.
9755 static bool CheapToScalarize(Value *V, bool isConstant) {
9756 if (isa<ConstantAggregateZero>(V))
9758 if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
9759 if (isConstant) return true;
9760 // If all elts are the same, we can extract.
9761 Constant *Op0 = C->getOperand(0);
9762 for (unsigned i = 1; i < C->getNumOperands(); ++i)
9763 if (C->getOperand(i) != Op0)
9767 Instruction *I = dyn_cast<Instruction>(V);
9768 if (!I) return false;
9770 // Insert element gets simplified to the inserted element or is deleted if
9771 // this is constant idx extract element and its a constant idx insertelt.
9772 if (I->getOpcode() == Instruction::InsertElement && isConstant &&
9773 isa<ConstantInt>(I->getOperand(2)))
9775 if (I->getOpcode() == Instruction::Load && I->hasOneUse())
9777 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
9778 if (BO->hasOneUse() &&
9779 (CheapToScalarize(BO->getOperand(0), isConstant) ||
9780 CheapToScalarize(BO->getOperand(1), isConstant)))
9782 if (CmpInst *CI = dyn_cast<CmpInst>(I))
9783 if (CI->hasOneUse() &&
9784 (CheapToScalarize(CI->getOperand(0), isConstant) ||
9785 CheapToScalarize(CI->getOperand(1), isConstant)))
9791 /// Read and decode a shufflevector mask.
9793 /// It turns undef elements into values that are larger than the number of
9794 /// elements in the input.
9795 static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
9796 unsigned NElts = SVI->getType()->getNumElements();
9797 if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
9798 return std::vector<unsigned>(NElts, 0);
9799 if (isa<UndefValue>(SVI->getOperand(2)))
9800 return std::vector<unsigned>(NElts, 2*NElts);
9802 std::vector<unsigned> Result;
9803 const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
9804 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
9805 if (isa<UndefValue>(CP->getOperand(i)))
9806 Result.push_back(NElts*2); // undef -> 8
9808 Result.push_back(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
9812 /// FindScalarElement - Given a vector and an element number, see if the scalar
9813 /// value is already around as a register, for example if it were inserted then
9814 /// extracted from the vector.
9815 static Value *FindScalarElement(Value *V, unsigned EltNo) {
9816 assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
9817 const VectorType *PTy = cast<VectorType>(V->getType());
9818 unsigned Width = PTy->getNumElements();
9819 if (EltNo >= Width) // Out of range access.
9820 return UndefValue::get(PTy->getElementType());
9822 if (isa<UndefValue>(V))
9823 return UndefValue::get(PTy->getElementType());
9824 else if (isa<ConstantAggregateZero>(V))
9825 return Constant::getNullValue(PTy->getElementType());
9826 else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
9827 return CP->getOperand(EltNo);
9828 else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
9829 // If this is an insert to a variable element, we don't know what it is.
9830 if (!isa<ConstantInt>(III->getOperand(2)))
9832 unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
9834 // If this is an insert to the element we are looking for, return the
9837 return III->getOperand(1);
9839 // Otherwise, the insertelement doesn't modify the value, recurse on its
9841 return FindScalarElement(III->getOperand(0), EltNo);
9842 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
9843 unsigned InEl = getShuffleMask(SVI)[EltNo];
9845 return FindScalarElement(SVI->getOperand(0), InEl);
9846 else if (InEl < Width*2)
9847 return FindScalarElement(SVI->getOperand(1), InEl - Width);
9849 return UndefValue::get(PTy->getElementType());
9852 // Otherwise, we don't know.
9856 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
9858 // If vector val is undef, replace extract with scalar undef.
9859 if (isa<UndefValue>(EI.getOperand(0)))
9860 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9862 // If vector val is constant 0, replace extract with scalar 0.
9863 if (isa<ConstantAggregateZero>(EI.getOperand(0)))
9864 return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
9866 if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
9867 // If vector val is constant with uniform operands, replace EI
9868 // with that operand
9869 Constant *op0 = C->getOperand(0);
9870 for (unsigned i = 1; i < C->getNumOperands(); ++i)
9871 if (C->getOperand(i) != op0) {
9876 return ReplaceInstUsesWith(EI, op0);
9879 // If extracting a specified index from the vector, see if we can recursively
9880 // find a previously computed scalar that was inserted into the vector.
9881 if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
9882 unsigned IndexVal = IdxC->getZExtValue();
9883 unsigned VectorWidth =
9884 cast<VectorType>(EI.getOperand(0)->getType())->getNumElements();
9886 // If this is extracting an invalid index, turn this into undef, to avoid
9887 // crashing the code below.
9888 if (IndexVal >= VectorWidth)
9889 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9891 // This instruction only demands the single element from the input vector.
9892 // If the input vector has a single use, simplify it based on this use
9894 if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
9896 if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
9899 EI.setOperand(0, V);
9904 if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
9905 return ReplaceInstUsesWith(EI, Elt);
9907 // If the this extractelement is directly using a bitcast from a vector of
9908 // the same number of elements, see if we can find the source element from
9909 // it. In this case, we will end up needing to bitcast the scalars.
9910 if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
9911 if (const VectorType *VT =
9912 dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
9913 if (VT->getNumElements() == VectorWidth)
9914 if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
9915 return new BitCastInst(Elt, EI.getType());
9919 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
9920 if (I->hasOneUse()) {
9921 // Push extractelement into predecessor operation if legal and
9922 // profitable to do so
9923 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
9924 bool isConstantElt = isa<ConstantInt>(EI.getOperand(1));
9925 if (CheapToScalarize(BO, isConstantElt)) {
9926 ExtractElementInst *newEI0 =
9927 new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
9928 EI.getName()+".lhs");
9929 ExtractElementInst *newEI1 =
9930 new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
9931 EI.getName()+".rhs");
9932 InsertNewInstBefore(newEI0, EI);
9933 InsertNewInstBefore(newEI1, EI);
9934 return BinaryOperator::create(BO->getOpcode(), newEI0, newEI1);
9936 } else if (isa<LoadInst>(I)) {
9938 cast<PointerType>(I->getOperand(0)->getType())->getAddressSpace();
9939 Value *Ptr = InsertCastBefore(Instruction::BitCast, I->getOperand(0),
9940 PointerType::get(EI.getType(), AS), EI);
9941 GetElementPtrInst *GEP =
9942 new GetElementPtrInst(Ptr, EI.getOperand(1), I->getName() + ".gep");
9943 InsertNewInstBefore(GEP, EI);
9944 return new LoadInst(GEP);
9947 if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
9948 // Extracting the inserted element?
9949 if (IE->getOperand(2) == EI.getOperand(1))
9950 return ReplaceInstUsesWith(EI, IE->getOperand(1));
9951 // If the inserted and extracted elements are constants, they must not
9952 // be the same value, extract from the pre-inserted value instead.
9953 if (isa<Constant>(IE->getOperand(2)) &&
9954 isa<Constant>(EI.getOperand(1))) {
9955 AddUsesToWorkList(EI);
9956 EI.setOperand(0, IE->getOperand(0));
9959 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
9960 // If this is extracting an element from a shufflevector, figure out where
9961 // it came from and extract from the appropriate input element instead.
9962 if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
9963 unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
9965 if (SrcIdx < SVI->getType()->getNumElements())
9966 Src = SVI->getOperand(0);
9967 else if (SrcIdx < SVI->getType()->getNumElements()*2) {
9968 SrcIdx -= SVI->getType()->getNumElements();
9969 Src = SVI->getOperand(1);
9971 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9973 return new ExtractElementInst(Src, SrcIdx);
9980 /// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
9981 /// elements from either LHS or RHS, return the shuffle mask and true.
9982 /// Otherwise, return false.
9983 static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
9984 std::vector<Constant*> &Mask) {
9985 assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
9986 "Invalid CollectSingleShuffleElements");
9987 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
9989 if (isa<UndefValue>(V)) {
9990 Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
9992 } else if (V == LHS) {
9993 for (unsigned i = 0; i != NumElts; ++i)
9994 Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
9996 } else if (V == RHS) {
9997 for (unsigned i = 0; i != NumElts; ++i)
9998 Mask.push_back(ConstantInt::get(Type::Int32Ty, i+NumElts));
10000 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
10001 // If this is an insert of an extract from some other vector, include it.
10002 Value *VecOp = IEI->getOperand(0);
10003 Value *ScalarOp = IEI->getOperand(1);
10004 Value *IdxOp = IEI->getOperand(2);
10006 if (!isa<ConstantInt>(IdxOp))
10008 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
10010 if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
10011 // Okay, we can handle this if the vector we are insertinting into is
10012 // transitively ok.
10013 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
10014 // If so, update the mask to reflect the inserted undef.
10015 Mask[InsertedIdx] = UndefValue::get(Type::Int32Ty);
10018 } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
10019 if (isa<ConstantInt>(EI->getOperand(1)) &&
10020 EI->getOperand(0)->getType() == V->getType()) {
10021 unsigned ExtractedIdx =
10022 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
10024 // This must be extracting from either LHS or RHS.
10025 if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
10026 // Okay, we can handle this if the vector we are insertinting into is
10027 // transitively ok.
10028 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
10029 // If so, update the mask to reflect the inserted value.
10030 if (EI->getOperand(0) == LHS) {
10031 Mask[InsertedIdx & (NumElts-1)] =
10032 ConstantInt::get(Type::Int32Ty, ExtractedIdx);
10034 assert(EI->getOperand(0) == RHS);
10035 Mask[InsertedIdx & (NumElts-1)] =
10036 ConstantInt::get(Type::Int32Ty, ExtractedIdx+NumElts);
10045 // TODO: Handle shufflevector here!
10050 /// CollectShuffleElements - We are building a shuffle of V, using RHS as the
10051 /// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
10052 /// that computes V and the LHS value of the shuffle.
10053 static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
10055 assert(isa<VectorType>(V->getType()) &&
10056 (RHS == 0 || V->getType() == RHS->getType()) &&
10057 "Invalid shuffle!");
10058 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
10060 if (isa<UndefValue>(V)) {
10061 Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
10063 } else if (isa<ConstantAggregateZero>(V)) {
10064 Mask.assign(NumElts, ConstantInt::get(Type::Int32Ty, 0));
10066 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
10067 // If this is an insert of an extract from some other vector, include it.
10068 Value *VecOp = IEI->getOperand(0);
10069 Value *ScalarOp = IEI->getOperand(1);
10070 Value *IdxOp = IEI->getOperand(2);
10072 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
10073 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
10074 EI->getOperand(0)->getType() == V->getType()) {
10075 unsigned ExtractedIdx =
10076 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
10077 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
10079 // Either the extracted from or inserted into vector must be RHSVec,
10080 // otherwise we'd end up with a shuffle of three inputs.
10081 if (EI->getOperand(0) == RHS || RHS == 0) {
10082 RHS = EI->getOperand(0);
10083 Value *V = CollectShuffleElements(VecOp, Mask, RHS);
10084 Mask[InsertedIdx & (NumElts-1)] =
10085 ConstantInt::get(Type::Int32Ty, NumElts+ExtractedIdx);
10089 if (VecOp == RHS) {
10090 Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
10091 // Everything but the extracted element is replaced with the RHS.
10092 for (unsigned i = 0; i != NumElts; ++i) {
10093 if (i != InsertedIdx)
10094 Mask[i] = ConstantInt::get(Type::Int32Ty, NumElts+i);
10099 // If this insertelement is a chain that comes from exactly these two
10100 // vectors, return the vector and the effective shuffle.
10101 if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
10102 return EI->getOperand(0);
10107 // TODO: Handle shufflevector here!
10109 // Otherwise, can't do anything fancy. Return an identity vector.
10110 for (unsigned i = 0; i != NumElts; ++i)
10111 Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
10115 Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
10116 Value *VecOp = IE.getOperand(0);
10117 Value *ScalarOp = IE.getOperand(1);
10118 Value *IdxOp = IE.getOperand(2);
10120 // Inserting an undef or into an undefined place, remove this.
10121 if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
10122 ReplaceInstUsesWith(IE, VecOp);
10124 // If the inserted element was extracted from some other vector, and if the
10125 // indexes are constant, try to turn this into a shufflevector operation.
10126 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
10127 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
10128 EI->getOperand(0)->getType() == IE.getType()) {
10129 unsigned NumVectorElts = IE.getType()->getNumElements();
10130 unsigned ExtractedIdx =
10131 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
10132 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
10134 if (ExtractedIdx >= NumVectorElts) // Out of range extract.
10135 return ReplaceInstUsesWith(IE, VecOp);
10137 if (InsertedIdx >= NumVectorElts) // Out of range insert.
10138 return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
10140 // If we are extracting a value from a vector, then inserting it right
10141 // back into the same place, just use the input vector.
10142 if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
10143 return ReplaceInstUsesWith(IE, VecOp);
10145 // We could theoretically do this for ANY input. However, doing so could
10146 // turn chains of insertelement instructions into a chain of shufflevector
10147 // instructions, and right now we do not merge shufflevectors. As such,
10148 // only do this in a situation where it is clear that there is benefit.
10149 if (isa<UndefValue>(VecOp) || isa<ConstantAggregateZero>(VecOp)) {
10150 // Turn this into shuffle(EIOp0, VecOp, Mask). The result has all of
10151 // the values of VecOp, except then one read from EIOp0.
10152 // Build a new shuffle mask.
10153 std::vector<Constant*> Mask;
10154 if (isa<UndefValue>(VecOp))
10155 Mask.assign(NumVectorElts, UndefValue::get(Type::Int32Ty));
10157 assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing");
10158 Mask.assign(NumVectorElts, ConstantInt::get(Type::Int32Ty,
10161 Mask[InsertedIdx] = ConstantInt::get(Type::Int32Ty, ExtractedIdx);
10162 return new ShuffleVectorInst(EI->getOperand(0), VecOp,
10163 ConstantVector::get(Mask));
10166 // If this insertelement isn't used by some other insertelement, turn it
10167 // (and any insertelements it points to), into one big shuffle.
10168 if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
10169 std::vector<Constant*> Mask;
10171 Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
10172 if (RHS == 0) RHS = UndefValue::get(LHS->getType());
10173 // We now have a shuffle of LHS, RHS, Mask.
10174 return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask));
10183 Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
10184 Value *LHS = SVI.getOperand(0);
10185 Value *RHS = SVI.getOperand(1);
10186 std::vector<unsigned> Mask = getShuffleMask(&SVI);
10188 bool MadeChange = false;
10190 // Undefined shuffle mask -> undefined value.
10191 if (isa<UndefValue>(SVI.getOperand(2)))
10192 return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
10194 // If we have shuffle(x, undef, mask) and any elements of mask refer to
10195 // the undef, change them to undefs.
10196 if (isa<UndefValue>(SVI.getOperand(1))) {
10197 // Scan to see if there are any references to the RHS. If so, replace them
10198 // with undef element refs and set MadeChange to true.
10199 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
10200 if (Mask[i] >= e && Mask[i] != 2*e) {
10207 // Remap any references to RHS to use LHS.
10208 std::vector<Constant*> Elts;
10209 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
10210 if (Mask[i] == 2*e)
10211 Elts.push_back(UndefValue::get(Type::Int32Ty));
10213 Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
10215 SVI.setOperand(2, ConstantVector::get(Elts));
10219 // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
10220 // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
10221 if (LHS == RHS || isa<UndefValue>(LHS)) {
10222 if (isa<UndefValue>(LHS) && LHS == RHS) {
10223 // shuffle(undef,undef,mask) -> undef.
10224 return ReplaceInstUsesWith(SVI, LHS);
10227 // Remap any references to RHS to use LHS.
10228 std::vector<Constant*> Elts;
10229 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
10230 if (Mask[i] >= 2*e)
10231 Elts.push_back(UndefValue::get(Type::Int32Ty));
10233 if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
10234 (Mask[i] < e && isa<UndefValue>(LHS)))
10235 Mask[i] = 2*e; // Turn into undef.
10237 Mask[i] &= (e-1); // Force to LHS.
10238 Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
10241 SVI.setOperand(0, SVI.getOperand(1));
10242 SVI.setOperand(1, UndefValue::get(RHS->getType()));
10243 SVI.setOperand(2, ConstantVector::get(Elts));
10244 LHS = SVI.getOperand(0);
10245 RHS = SVI.getOperand(1);
10249 // Analyze the shuffle, are the LHS or RHS and identity shuffles?
10250 bool isLHSID = true, isRHSID = true;
10252 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
10253 if (Mask[i] >= e*2) continue; // Ignore undef values.
10254 // Is this an identity shuffle of the LHS value?
10255 isLHSID &= (Mask[i] == i);
10257 // Is this an identity shuffle of the RHS value?
10258 isRHSID &= (Mask[i]-e == i);
10261 // Eliminate identity shuffles.
10262 if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
10263 if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
10265 // If the LHS is a shufflevector itself, see if we can combine it with this
10266 // one without producing an unusual shuffle. Here we are really conservative:
10267 // we are absolutely afraid of producing a shuffle mask not in the input
10268 // program, because the code gen may not be smart enough to turn a merged
10269 // shuffle into two specific shuffles: it may produce worse code. As such,
10270 // we only merge two shuffles if the result is one of the two input shuffle
10271 // masks. In this case, merging the shuffles just removes one instruction,
10272 // which we know is safe. This is good for things like turning:
10273 // (splat(splat)) -> splat.
10274 if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
10275 if (isa<UndefValue>(RHS)) {
10276 std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
10278 std::vector<unsigned> NewMask;
10279 for (unsigned i = 0, e = Mask.size(); i != e; ++i)
10280 if (Mask[i] >= 2*e)
10281 NewMask.push_back(2*e);
10283 NewMask.push_back(LHSMask[Mask[i]]);
10285 // If the result mask is equal to the src shuffle or this shuffle mask, do
10286 // the replacement.
10287 if (NewMask == LHSMask || NewMask == Mask) {
10288 std::vector<Constant*> Elts;
10289 for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
10290 if (NewMask[i] >= e*2) {
10291 Elts.push_back(UndefValue::get(Type::Int32Ty));
10293 Elts.push_back(ConstantInt::get(Type::Int32Ty, NewMask[i]));
10296 return new ShuffleVectorInst(LHSSVI->getOperand(0),
10297 LHSSVI->getOperand(1),
10298 ConstantVector::get(Elts));
10303 return MadeChange ? &SVI : 0;
10309 /// TryToSinkInstruction - Try to move the specified instruction from its
10310 /// current block into the beginning of DestBlock, which can only happen if it's
10311 /// safe to move the instruction past all of the instructions between it and the
10312 /// end of its block.
10313 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
10314 assert(I->hasOneUse() && "Invariants didn't hold!");
10316 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
10317 if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
10319 // Do not sink alloca instructions out of the entry block.
10320 if (isa<AllocaInst>(I) && I->getParent() ==
10321 &DestBlock->getParent()->getEntryBlock())
10324 // We can only sink load instructions if there is nothing between the load and
10325 // the end of block that could change the value.
10326 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
10327 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
10329 if (Scan->mayWriteToMemory())
10333 BasicBlock::iterator InsertPos = DestBlock->begin();
10334 while (isa<PHINode>(InsertPos)) ++InsertPos;
10336 I->moveBefore(InsertPos);
10342 /// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
10343 /// all reachable code to the worklist.
10345 /// This has a couple of tricks to make the code faster and more powerful. In
10346 /// particular, we constant fold and DCE instructions as we go, to avoid adding
10347 /// them to the worklist (this significantly speeds up instcombine on code where
10348 /// many instructions are dead or constant). Additionally, if we find a branch
10349 /// whose condition is a known constant, we only visit the reachable successors.
10351 static void AddReachableCodeToWorklist(BasicBlock *BB,
10352 SmallPtrSet<BasicBlock*, 64> &Visited,
10354 const TargetData *TD) {
10355 std::vector<BasicBlock*> Worklist;
10356 Worklist.push_back(BB);
10358 while (!Worklist.empty()) {
10359 BB = Worklist.back();
10360 Worklist.pop_back();
10362 // We have now visited this block! If we've already been here, ignore it.
10363 if (!Visited.insert(BB)) continue;
10365 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
10366 Instruction *Inst = BBI++;
10368 // DCE instruction if trivially dead.
10369 if (isInstructionTriviallyDead(Inst)) {
10371 DOUT << "IC: DCE: " << *Inst;
10372 Inst->eraseFromParent();
10376 // ConstantProp instruction if trivially constant.
10377 if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
10378 DOUT << "IC: ConstFold to: " << *C << " from: " << *Inst;
10379 Inst->replaceAllUsesWith(C);
10381 Inst->eraseFromParent();
10385 IC.AddToWorkList(Inst);
10388 // Recursively visit successors. If this is a branch or switch on a
10389 // constant, only visit the reachable successor.
10390 TerminatorInst *TI = BB->getTerminator();
10391 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
10392 if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
10393 bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
10394 Worklist.push_back(BI->getSuccessor(!CondVal));
10397 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
10398 if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
10399 // See if this is an explicit destination.
10400 for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
10401 if (SI->getCaseValue(i) == Cond) {
10402 Worklist.push_back(SI->getSuccessor(i));
10406 // Otherwise it is the default destination.
10407 Worklist.push_back(SI->getSuccessor(0));
10412 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
10413 Worklist.push_back(TI->getSuccessor(i));
10417 bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
10418 bool Changed = false;
10419 TD = &getAnalysis<TargetData>();
10421 DEBUG(DOUT << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
10422 << F.getNameStr() << "\n");
10425 // Do a depth-first traversal of the function, populate the worklist with
10426 // the reachable instructions. Ignore blocks that are not reachable. Keep
10427 // track of which blocks we visit.
10428 SmallPtrSet<BasicBlock*, 64> Visited;
10429 AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
10431 // Do a quick scan over the function. If we find any blocks that are
10432 // unreachable, remove any instructions inside of them. This prevents
10433 // the instcombine code from having to deal with some bad special cases.
10434 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
10435 if (!Visited.count(BB)) {
10436 Instruction *Term = BB->getTerminator();
10437 while (Term != BB->begin()) { // Remove instrs bottom-up
10438 BasicBlock::iterator I = Term; --I;
10440 DOUT << "IC: DCE: " << *I;
10443 if (!I->use_empty())
10444 I->replaceAllUsesWith(UndefValue::get(I->getType()));
10445 I->eraseFromParent();
10450 while (!Worklist.empty()) {
10451 Instruction *I = RemoveOneFromWorkList();
10452 if (I == 0) continue; // skip null values.
10454 // Check to see if we can DCE the instruction.
10455 if (isInstructionTriviallyDead(I)) {
10456 // Add operands to the worklist.
10457 if (I->getNumOperands() < 4)
10458 AddUsesToWorkList(*I);
10461 DOUT << "IC: DCE: " << *I;
10463 I->eraseFromParent();
10464 RemoveFromWorkList(I);
10468 // Instruction isn't dead, see if we can constant propagate it.
10469 if (Constant *C = ConstantFoldInstruction(I, TD)) {
10470 DOUT << "IC: ConstFold to: " << *C << " from: " << *I;
10472 // Add operands to the worklist.
10473 AddUsesToWorkList(*I);
10474 ReplaceInstUsesWith(*I, C);
10477 I->eraseFromParent();
10478 RemoveFromWorkList(I);
10482 // See if we can trivially sink this instruction to a successor basic block.
10483 if (I->hasOneUse()) {
10484 BasicBlock *BB = I->getParent();
10485 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
10486 if (UserParent != BB) {
10487 bool UserIsSuccessor = false;
10488 // See if the user is one of our successors.
10489 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
10490 if (*SI == UserParent) {
10491 UserIsSuccessor = true;
10495 // If the user is one of our immediate successors, and if that successor
10496 // only has us as a predecessors (we'd have to split the critical edge
10497 // otherwise), we can keep going.
10498 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
10499 next(pred_begin(UserParent)) == pred_end(UserParent))
10500 // Okay, the CFG is simple enough, try to sink this instruction.
10501 Changed |= TryToSinkInstruction(I, UserParent);
10505 // Now that we have an instruction, try combining it to simplify it...
10509 DEBUG(std::ostringstream SS; I->print(SS); OrigI = SS.str(););
10510 if (Instruction *Result = visit(*I)) {
10512 // Should we replace the old instruction with a new one?
10514 DOUT << "IC: Old = " << *I
10515 << " New = " << *Result;
10517 // Everything uses the new instruction now.
10518 I->replaceAllUsesWith(Result);
10520 // Push the new instruction and any users onto the worklist.
10521 AddToWorkList(Result);
10522 AddUsersToWorkList(*Result);
10524 // Move the name to the new instruction first.
10525 Result->takeName(I);
10527 // Insert the new instruction into the basic block...
10528 BasicBlock *InstParent = I->getParent();
10529 BasicBlock::iterator InsertPos = I;
10531 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
10532 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
10535 InstParent->getInstList().insert(InsertPos, Result);
10537 // Make sure that we reprocess all operands now that we reduced their
10539 AddUsesToWorkList(*I);
10541 // Instructions can end up on the worklist more than once. Make sure
10542 // we do not process an instruction that has been deleted.
10543 RemoveFromWorkList(I);
10545 // Erase the old instruction.
10546 InstParent->getInstList().erase(I);
10549 DOUT << "IC: Mod = " << OrigI
10550 << " New = " << *I;
10553 // If the instruction was modified, it's possible that it is now dead.
10554 // if so, remove it.
10555 if (isInstructionTriviallyDead(I)) {
10556 // Make sure we process all operands now that we are reducing their
10558 AddUsesToWorkList(*I);
10560 // Instructions may end up in the worklist more than once. Erase all
10561 // occurrences of this instruction.
10562 RemoveFromWorkList(I);
10563 I->eraseFromParent();
10566 AddUsersToWorkList(*I);
10573 assert(WorklistMap.empty() && "Worklist empty, but map not?");
10575 // Do an explicit clear, this shrinks the map if needed.
10576 WorklistMap.clear();
10581 bool InstCombiner::runOnFunction(Function &F) {
10582 MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
10584 bool EverMadeChange = false;
10586 // Iterate while there is work to do.
10587 unsigned Iteration = 0;
10588 while (DoOneIteration(F, Iteration++))
10589 EverMadeChange = true;
10590 return EverMadeChange;
10593 FunctionPass *llvm::createInstructionCombiningPass() {
10594 return new InstCombiner();