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())) {
2125 Value *I2 = InsertCastBefore(Instruction::BitCast, CI->getOperand(0),
2126 PointerType::get(Type::Int8Ty), I);
2127 I2 = InsertNewInstBefore(new GetElementPtrInst(I2, Other, "ctg2"), I);
2128 return new PtrToIntInst(I2, CI->getType());
2132 return Changed ? &I : 0;
2135 // isSignBit - Return true if the value represented by the constant only has the
2136 // highest order bit set.
2137 static bool isSignBit(ConstantInt *CI) {
2138 uint32_t NumBits = CI->getType()->getPrimitiveSizeInBits();
2139 return CI->getValue() == APInt::getSignBit(NumBits);
2142 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
2143 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2145 if (Op0 == Op1) // sub X, X -> 0
2146 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2148 // If this is a 'B = x-(-A)', change to B = x+A...
2149 if (Value *V = dyn_castNegVal(Op1))
2150 return BinaryOperator::createAdd(Op0, V);
2152 if (isa<UndefValue>(Op0))
2153 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
2154 if (isa<UndefValue>(Op1))
2155 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
2157 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
2158 // Replace (-1 - A) with (~A)...
2159 if (C->isAllOnesValue())
2160 return BinaryOperator::createNot(Op1);
2162 // C - ~X == X + (1+C)
2164 if (match(Op1, m_Not(m_Value(X))))
2165 return BinaryOperator::createAdd(X, AddOne(C));
2167 // -(X >>u 31) -> (X >>s 31)
2168 // -(X >>s 31) -> (X >>u 31)
2170 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1))
2171 if (SI->getOpcode() == Instruction::LShr) {
2172 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
2173 // Check to see if we are shifting out everything but the sign bit.
2174 if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
2175 SI->getType()->getPrimitiveSizeInBits()-1) {
2176 // Ok, the transformation is safe. Insert AShr.
2177 return BinaryOperator::create(Instruction::AShr,
2178 SI->getOperand(0), CU, SI->getName());
2182 else if (SI->getOpcode() == Instruction::AShr) {
2183 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
2184 // Check to see if we are shifting out everything but the sign bit.
2185 if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
2186 SI->getType()->getPrimitiveSizeInBits()-1) {
2187 // Ok, the transformation is safe. Insert LShr.
2188 return BinaryOperator::createLShr(
2189 SI->getOperand(0), CU, SI->getName());
2195 // Try to fold constant sub into select arguments.
2196 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
2197 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2200 if (isa<PHINode>(Op0))
2201 if (Instruction *NV = FoldOpIntoPhi(I))
2205 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
2206 if (Op1I->getOpcode() == Instruction::Add &&
2207 !Op0->getType()->isFPOrFPVector()) {
2208 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
2209 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
2210 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
2211 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
2212 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
2213 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
2214 // C1-(X+C2) --> (C1-C2)-X
2215 return BinaryOperator::createSub(Subtract(CI1, CI2),
2216 Op1I->getOperand(0));
2220 if (Op1I->hasOneUse()) {
2221 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
2222 // is not used by anyone else...
2224 if (Op1I->getOpcode() == Instruction::Sub &&
2225 !Op1I->getType()->isFPOrFPVector()) {
2226 // Swap the two operands of the subexpr...
2227 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
2228 Op1I->setOperand(0, IIOp1);
2229 Op1I->setOperand(1, IIOp0);
2231 // Create the new top level add instruction...
2232 return BinaryOperator::createAdd(Op0, Op1);
2235 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
2237 if (Op1I->getOpcode() == Instruction::And &&
2238 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
2239 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
2242 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
2243 return BinaryOperator::createAnd(Op0, NewNot);
2246 // 0 - (X sdiv C) -> (X sdiv -C)
2247 if (Op1I->getOpcode() == Instruction::SDiv)
2248 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
2250 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
2251 return BinaryOperator::createSDiv(Op1I->getOperand(0),
2252 ConstantExpr::getNeg(DivRHS));
2254 // X - X*C --> X * (1-C)
2255 ConstantInt *C2 = 0;
2256 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
2257 Constant *CP1 = Subtract(ConstantInt::get(I.getType(), 1), C2);
2258 return BinaryOperator::createMul(Op0, CP1);
2261 // X - ((X / Y) * Y) --> X % Y
2262 if (Op1I->getOpcode() == Instruction::Mul)
2263 if (Instruction *I = dyn_cast<Instruction>(Op1I->getOperand(0)))
2264 if (Op0 == I->getOperand(0) &&
2265 Op1I->getOperand(1) == I->getOperand(1)) {
2266 if (I->getOpcode() == Instruction::SDiv)
2267 return BinaryOperator::createSRem(Op0, Op1I->getOperand(1));
2268 if (I->getOpcode() == Instruction::UDiv)
2269 return BinaryOperator::createURem(Op0, Op1I->getOperand(1));
2274 if (!Op0->getType()->isFPOrFPVector())
2275 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
2276 if (Op0I->getOpcode() == Instruction::Add) {
2277 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
2278 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2279 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
2280 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2281 } else if (Op0I->getOpcode() == Instruction::Sub) {
2282 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
2283 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
2287 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
2288 if (X == Op1) // X*C - X --> X * (C-1)
2289 return BinaryOperator::createMul(Op1, SubOne(C1));
2291 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
2292 if (X == dyn_castFoldableMul(Op1, C2))
2293 return BinaryOperator::createMul(Op1, Subtract(C1, C2));
2298 /// isSignBitCheck - Given an exploded icmp instruction, return true if the
2299 /// comparison only checks the sign bit. If it only checks the sign bit, set
2300 /// TrueIfSigned if the result of the comparison is true when the input value is
2302 static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
2303 bool &TrueIfSigned) {
2305 case ICmpInst::ICMP_SLT: // True if LHS s< 0
2306 TrueIfSigned = true;
2307 return RHS->isZero();
2308 case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
2309 TrueIfSigned = true;
2310 return RHS->isAllOnesValue();
2311 case ICmpInst::ICMP_SGT: // True if LHS s> -1
2312 TrueIfSigned = false;
2313 return RHS->isAllOnesValue();
2314 case ICmpInst::ICMP_UGT:
2315 // True if LHS u> RHS and RHS == high-bit-mask - 1
2316 TrueIfSigned = true;
2317 return RHS->getValue() ==
2318 APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
2319 case ICmpInst::ICMP_UGE:
2320 // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
2321 TrueIfSigned = true;
2322 return RHS->getValue() ==
2323 APInt::getSignBit(RHS->getType()->getPrimitiveSizeInBits());
2329 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
2330 bool Changed = SimplifyCommutative(I);
2331 Value *Op0 = I.getOperand(0);
2333 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
2334 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2336 // Simplify mul instructions with a constant RHS...
2337 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
2338 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2340 // ((X << C1)*C2) == (X * (C2 << C1))
2341 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
2342 if (SI->getOpcode() == Instruction::Shl)
2343 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
2344 return BinaryOperator::createMul(SI->getOperand(0),
2345 ConstantExpr::getShl(CI, ShOp));
2348 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
2349 if (CI->equalsInt(1)) // X * 1 == X
2350 return ReplaceInstUsesWith(I, Op0);
2351 if (CI->isAllOnesValue()) // X * -1 == 0 - X
2352 return BinaryOperator::createNeg(Op0, I.getName());
2354 const APInt& Val = cast<ConstantInt>(CI)->getValue();
2355 if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
2356 return BinaryOperator::createShl(Op0,
2357 ConstantInt::get(Op0->getType(), Val.logBase2()));
2359 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
2360 if (Op1F->isNullValue())
2361 return ReplaceInstUsesWith(I, Op1);
2363 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
2364 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
2365 // We need a better interface for long double here.
2366 if (Op1->getType() == Type::FloatTy || Op1->getType() == Type::DoubleTy)
2367 if (Op1F->isExactlyValue(1.0))
2368 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
2371 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
2372 if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
2373 isa<ConstantInt>(Op0I->getOperand(1))) {
2374 // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
2375 Instruction *Add = BinaryOperator::createMul(Op0I->getOperand(0),
2377 InsertNewInstBefore(Add, I);
2378 Value *C1C2 = ConstantExpr::getMul(Op1,
2379 cast<Constant>(Op0I->getOperand(1)));
2380 return BinaryOperator::createAdd(Add, C1C2);
2384 // Try to fold constant mul into select arguments.
2385 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2386 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2389 if (isa<PHINode>(Op0))
2390 if (Instruction *NV = FoldOpIntoPhi(I))
2394 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
2395 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
2396 return BinaryOperator::createMul(Op0v, Op1v);
2398 // If one of the operands of the multiply is a cast from a boolean value, then
2399 // we know the bool is either zero or one, so this is a 'masking' multiply.
2400 // See if we can simplify things based on how the boolean was originally
2402 CastInst *BoolCast = 0;
2403 if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(0)))
2404 if (CI->getOperand(0)->getType() == Type::Int1Ty)
2407 if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(1)))
2408 if (CI->getOperand(0)->getType() == Type::Int1Ty)
2411 if (ICmpInst *SCI = dyn_cast<ICmpInst>(BoolCast->getOperand(0))) {
2412 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
2413 const Type *SCOpTy = SCIOp0->getType();
2416 // If the icmp is true iff the sign bit of X is set, then convert this
2417 // multiply into a shift/and combination.
2418 if (isa<ConstantInt>(SCIOp1) &&
2419 isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1), TIS) &&
2421 // Shift the X value right to turn it into "all signbits".
2422 Constant *Amt = ConstantInt::get(SCIOp0->getType(),
2423 SCOpTy->getPrimitiveSizeInBits()-1);
2425 InsertNewInstBefore(
2426 BinaryOperator::create(Instruction::AShr, SCIOp0, Amt,
2427 BoolCast->getOperand(0)->getName()+
2430 // If the multiply type is not the same as the source type, sign extend
2431 // or truncate to the multiply type.
2432 if (I.getType() != V->getType()) {
2433 uint32_t SrcBits = V->getType()->getPrimitiveSizeInBits();
2434 uint32_t DstBits = I.getType()->getPrimitiveSizeInBits();
2435 Instruction::CastOps opcode =
2436 (SrcBits == DstBits ? Instruction::BitCast :
2437 (SrcBits < DstBits ? Instruction::SExt : Instruction::Trunc));
2438 V = InsertCastBefore(opcode, V, I.getType(), I);
2441 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
2442 return BinaryOperator::createAnd(V, OtherOp);
2447 return Changed ? &I : 0;
2450 /// This function implements the transforms on div instructions that work
2451 /// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
2452 /// used by the visitors to those instructions.
2453 /// @brief Transforms common to all three div instructions
2454 Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
2455 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2458 if (isa<UndefValue>(Op0))
2459 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2461 // X / undef -> undef
2462 if (isa<UndefValue>(Op1))
2463 return ReplaceInstUsesWith(I, Op1);
2465 // Handle cases involving: div X, (select Cond, Y, Z)
2466 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
2467 // div X, (Cond ? 0 : Y) -> div X, Y. If the div and the select are in the
2468 // same basic block, then we replace the select with Y, and the condition
2469 // of the select with false (if the cond value is in the same BB). If the
2470 // select has uses other than the div, this allows them to be simplified
2471 // also. Note that div X, Y is just as good as div X, 0 (undef)
2472 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
2473 if (ST->isNullValue()) {
2474 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
2475 if (CondI && CondI->getParent() == I.getParent())
2476 UpdateValueUsesWith(CondI, ConstantInt::getFalse());
2477 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
2478 I.setOperand(1, SI->getOperand(2));
2480 UpdateValueUsesWith(SI, SI->getOperand(2));
2484 // Likewise for: div X, (Cond ? Y : 0) -> div X, Y
2485 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
2486 if (ST->isNullValue()) {
2487 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
2488 if (CondI && CondI->getParent() == I.getParent())
2489 UpdateValueUsesWith(CondI, ConstantInt::getTrue());
2490 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
2491 I.setOperand(1, SI->getOperand(1));
2493 UpdateValueUsesWith(SI, SI->getOperand(1));
2501 /// This function implements the transforms common to both integer division
2502 /// instructions (udiv and sdiv). It is called by the visitors to those integer
2503 /// division instructions.
2504 /// @brief Common integer divide transforms
2505 Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
2506 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2508 if (Instruction *Common = commonDivTransforms(I))
2511 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2513 if (RHS->equalsInt(1))
2514 return ReplaceInstUsesWith(I, Op0);
2516 // (X / C1) / C2 -> X / (C1*C2)
2517 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
2518 if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
2519 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
2520 return BinaryOperator::create(I.getOpcode(), LHS->getOperand(0),
2521 Multiply(RHS, LHSRHS));
2524 if (!RHS->isZero()) { // avoid X udiv 0
2525 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2526 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2528 if (isa<PHINode>(Op0))
2529 if (Instruction *NV = FoldOpIntoPhi(I))
2534 // 0 / X == 0, we don't need to preserve faults!
2535 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
2536 if (LHS->equalsInt(0))
2537 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2542 Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
2543 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2545 // Handle the integer div common cases
2546 if (Instruction *Common = commonIDivTransforms(I))
2549 // X udiv C^2 -> X >> C
2550 // Check to see if this is an unsigned division with an exact power of 2,
2551 // if so, convert to a right shift.
2552 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
2553 if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
2554 return BinaryOperator::createLShr(Op0,
2555 ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
2558 // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
2559 if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
2560 if (RHSI->getOpcode() == Instruction::Shl &&
2561 isa<ConstantInt>(RHSI->getOperand(0))) {
2562 const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
2563 if (C1.isPowerOf2()) {
2564 Value *N = RHSI->getOperand(1);
2565 const Type *NTy = N->getType();
2566 if (uint32_t C2 = C1.logBase2()) {
2567 Constant *C2V = ConstantInt::get(NTy, C2);
2568 N = InsertNewInstBefore(BinaryOperator::createAdd(N, C2V, "tmp"), I);
2570 return BinaryOperator::createLShr(Op0, N);
2575 // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
2576 // where C1&C2 are powers of two.
2577 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
2578 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
2579 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
2580 const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
2581 if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
2582 // Compute the shift amounts
2583 uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
2584 // Construct the "on true" case of the select
2585 Constant *TC = ConstantInt::get(Op0->getType(), TSA);
2586 Instruction *TSI = BinaryOperator::createLShr(
2587 Op0, TC, SI->getName()+".t");
2588 TSI = InsertNewInstBefore(TSI, I);
2590 // Construct the "on false" case of the select
2591 Constant *FC = ConstantInt::get(Op0->getType(), FSA);
2592 Instruction *FSI = BinaryOperator::createLShr(
2593 Op0, FC, SI->getName()+".f");
2594 FSI = InsertNewInstBefore(FSI, I);
2596 // construct the select instruction and return it.
2597 return new SelectInst(SI->getOperand(0), TSI, FSI, SI->getName());
2603 Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
2604 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2606 // Handle the integer div common cases
2607 if (Instruction *Common = commonIDivTransforms(I))
2610 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2612 if (RHS->isAllOnesValue())
2613 return BinaryOperator::createNeg(Op0);
2616 if (Value *LHSNeg = dyn_castNegVal(Op0))
2617 return BinaryOperator::createSDiv(LHSNeg, ConstantExpr::getNeg(RHS));
2620 // If the sign bits of both operands are zero (i.e. we can prove they are
2621 // unsigned inputs), turn this into a udiv.
2622 if (I.getType()->isInteger()) {
2623 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
2624 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
2625 // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
2626 return BinaryOperator::createUDiv(Op0, Op1, I.getName());
2633 Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
2634 return commonDivTransforms(I);
2637 /// GetFactor - If we can prove that the specified value is at least a multiple
2638 /// of some factor, return that factor.
2639 static Constant *GetFactor(Value *V) {
2640 if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
2643 // Unless we can be tricky, we know this is a multiple of 1.
2644 Constant *Result = ConstantInt::get(V->getType(), 1);
2646 Instruction *I = dyn_cast<Instruction>(V);
2647 if (!I) return Result;
2649 if (I->getOpcode() == Instruction::Mul) {
2650 // Handle multiplies by a constant, etc.
2651 return ConstantExpr::getMul(GetFactor(I->getOperand(0)),
2652 GetFactor(I->getOperand(1)));
2653 } else if (I->getOpcode() == Instruction::Shl) {
2654 // (X<<C) -> X * (1 << C)
2655 if (Constant *ShRHS = dyn_cast<Constant>(I->getOperand(1))) {
2656 ShRHS = ConstantExpr::getShl(Result, ShRHS);
2657 return ConstantExpr::getMul(GetFactor(I->getOperand(0)), ShRHS);
2659 } else if (I->getOpcode() == Instruction::And) {
2660 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
2661 // X & 0xFFF0 is known to be a multiple of 16.
2662 uint32_t Zeros = RHS->getValue().countTrailingZeros();
2663 if (Zeros != V->getType()->getPrimitiveSizeInBits())
2664 return ConstantExpr::getShl(Result,
2665 ConstantInt::get(Result->getType(), Zeros));
2667 } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
2668 // Only handle int->int casts.
2669 if (!CI->isIntegerCast())
2671 Value *Op = CI->getOperand(0);
2672 return ConstantExpr::getCast(CI->getOpcode(), GetFactor(Op), V->getType());
2677 /// This function implements the transforms on rem instructions that work
2678 /// regardless of the kind of rem instruction it is (urem, srem, or frem). It
2679 /// is used by the visitors to those instructions.
2680 /// @brief Transforms common to all three rem instructions
2681 Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
2682 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2684 // 0 % X == 0, we don't need to preserve faults!
2685 if (Constant *LHS = dyn_cast<Constant>(Op0))
2686 if (LHS->isNullValue())
2687 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2689 if (isa<UndefValue>(Op0)) // undef % X -> 0
2690 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2691 if (isa<UndefValue>(Op1))
2692 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
2694 // Handle cases involving: rem X, (select Cond, Y, Z)
2695 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
2696 // rem X, (Cond ? 0 : Y) -> rem X, Y. If the rem and the select are in
2697 // the same basic block, then we replace the select with Y, and the
2698 // condition of the select with false (if the cond value is in the same
2699 // BB). If the select has uses other than the div, this allows them to be
2701 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
2702 if (ST->isNullValue()) {
2703 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
2704 if (CondI && CondI->getParent() == I.getParent())
2705 UpdateValueUsesWith(CondI, ConstantInt::getFalse());
2706 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
2707 I.setOperand(1, SI->getOperand(2));
2709 UpdateValueUsesWith(SI, SI->getOperand(2));
2712 // Likewise for: rem X, (Cond ? Y : 0) -> rem X, Y
2713 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
2714 if (ST->isNullValue()) {
2715 Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
2716 if (CondI && CondI->getParent() == I.getParent())
2717 UpdateValueUsesWith(CondI, ConstantInt::getTrue());
2718 else if (I.getParent() != SI->getParent() || SI->hasOneUse())
2719 I.setOperand(1, SI->getOperand(1));
2721 UpdateValueUsesWith(SI, SI->getOperand(1));
2729 /// This function implements the transforms common to both integer remainder
2730 /// instructions (urem and srem). It is called by the visitors to those integer
2731 /// remainder instructions.
2732 /// @brief Common integer remainder transforms
2733 Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
2734 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2736 if (Instruction *common = commonRemTransforms(I))
2739 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2740 // X % 0 == undef, we don't need to preserve faults!
2741 if (RHS->equalsInt(0))
2742 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2744 if (RHS->equalsInt(1)) // X % 1 == 0
2745 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2747 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
2748 if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
2749 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2751 } else if (isa<PHINode>(Op0I)) {
2752 if (Instruction *NV = FoldOpIntoPhi(I))
2755 // (X * C1) % C2 --> 0 iff C1 % C2 == 0
2756 if (ConstantExpr::getSRem(GetFactor(Op0I), RHS)->isNullValue())
2757 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2764 Instruction *InstCombiner::visitURem(BinaryOperator &I) {
2765 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2767 if (Instruction *common = commonIRemTransforms(I))
2770 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2771 // X urem C^2 -> X and C
2772 // Check to see if this is an unsigned remainder with an exact power of 2,
2773 // if so, convert to a bitwise and.
2774 if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
2775 if (C->getValue().isPowerOf2())
2776 return BinaryOperator::createAnd(Op0, SubOne(C));
2779 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
2780 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
2781 if (RHSI->getOpcode() == Instruction::Shl &&
2782 isa<ConstantInt>(RHSI->getOperand(0))) {
2783 if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
2784 Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
2785 Value *Add = InsertNewInstBefore(BinaryOperator::createAdd(RHSI, N1,
2787 return BinaryOperator::createAnd(Op0, Add);
2792 // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
2793 // where C1&C2 are powers of two.
2794 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
2795 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
2796 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
2797 // STO == 0 and SFO == 0 handled above.
2798 if ((STO->getValue().isPowerOf2()) &&
2799 (SFO->getValue().isPowerOf2())) {
2800 Value *TrueAnd = InsertNewInstBefore(
2801 BinaryOperator::createAnd(Op0, SubOne(STO), SI->getName()+".t"), I);
2802 Value *FalseAnd = InsertNewInstBefore(
2803 BinaryOperator::createAnd(Op0, SubOne(SFO), SI->getName()+".f"), I);
2804 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
2812 Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
2813 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2815 // Handle the integer rem common cases
2816 if (Instruction *common = commonIRemTransforms(I))
2819 if (Value *RHSNeg = dyn_castNegVal(Op1))
2820 if (!isa<ConstantInt>(RHSNeg) ||
2821 cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive()) {
2823 AddUsesToWorkList(I);
2824 I.setOperand(1, RHSNeg);
2828 // If the sign bits of both operands are zero (i.e. we can prove they are
2829 // unsigned inputs), turn this into a urem.
2830 if (I.getType()->isInteger()) {
2831 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
2832 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
2833 // X srem Y -> X urem Y, iff X and Y don't have sign bit set
2834 return BinaryOperator::createURem(Op0, Op1, I.getName());
2841 Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
2842 return commonRemTransforms(I);
2845 // isMaxValueMinusOne - return true if this is Max-1
2846 static bool isMaxValueMinusOne(const ConstantInt *C, bool isSigned) {
2847 uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
2849 return C->getValue() == APInt::getAllOnesValue(TypeBits) - 1;
2850 return C->getValue() == APInt::getSignedMaxValue(TypeBits)-1;
2853 // isMinValuePlusOne - return true if this is Min+1
2854 static bool isMinValuePlusOne(const ConstantInt *C, bool isSigned) {
2856 return C->getValue() == 1; // unsigned
2858 // Calculate 1111111111000000000000
2859 uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
2860 return C->getValue() == APInt::getSignedMinValue(TypeBits)+1;
2863 // isOneBitSet - Return true if there is exactly one bit set in the specified
2865 static bool isOneBitSet(const ConstantInt *CI) {
2866 return CI->getValue().isPowerOf2();
2869 // isHighOnes - Return true if the constant is of the form 1+0+.
2870 // This is the same as lowones(~X).
2871 static bool isHighOnes(const ConstantInt *CI) {
2872 return (~CI->getValue() + 1).isPowerOf2();
2875 /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
2876 /// are carefully arranged to allow folding of expressions such as:
2878 /// (A < B) | (A > B) --> (A != B)
2880 /// Note that this is only valid if the first and second predicates have the
2881 /// same sign. Is illegal to do: (A u< B) | (A s> B)
2883 /// Three bits are used to represent the condition, as follows:
2888 /// <=> Value Definition
2889 /// 000 0 Always false
2896 /// 111 7 Always true
2898 static unsigned getICmpCode(const ICmpInst *ICI) {
2899 switch (ICI->getPredicate()) {
2901 case ICmpInst::ICMP_UGT: return 1; // 001
2902 case ICmpInst::ICMP_SGT: return 1; // 001
2903 case ICmpInst::ICMP_EQ: return 2; // 010
2904 case ICmpInst::ICMP_UGE: return 3; // 011
2905 case ICmpInst::ICMP_SGE: return 3; // 011
2906 case ICmpInst::ICMP_ULT: return 4; // 100
2907 case ICmpInst::ICMP_SLT: return 4; // 100
2908 case ICmpInst::ICMP_NE: return 5; // 101
2909 case ICmpInst::ICMP_ULE: return 6; // 110
2910 case ICmpInst::ICMP_SLE: return 6; // 110
2913 assert(0 && "Invalid ICmp predicate!");
2918 /// getICmpValue - This is the complement of getICmpCode, which turns an
2919 /// opcode and two operands into either a constant true or false, or a brand
2920 /// new ICmp instruction. The sign is passed in to determine which kind
2921 /// of predicate to use in new icmp instructions.
2922 static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS) {
2924 default: assert(0 && "Illegal ICmp code!");
2925 case 0: return ConstantInt::getFalse();
2928 return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
2930 return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
2931 case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
2934 return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
2936 return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
2939 return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
2941 return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
2942 case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
2945 return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
2947 return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
2948 case 7: return ConstantInt::getTrue();
2952 static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
2953 return (ICmpInst::isSignedPredicate(p1) == ICmpInst::isSignedPredicate(p2)) ||
2954 (ICmpInst::isSignedPredicate(p1) &&
2955 (p2 == ICmpInst::ICMP_EQ || p2 == ICmpInst::ICMP_NE)) ||
2956 (ICmpInst::isSignedPredicate(p2) &&
2957 (p1 == ICmpInst::ICMP_EQ || p1 == ICmpInst::ICMP_NE));
2961 // FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
2962 struct FoldICmpLogical {
2965 ICmpInst::Predicate pred;
2966 FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
2967 : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
2968 pred(ICI->getPredicate()) {}
2969 bool shouldApply(Value *V) const {
2970 if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
2971 if (PredicatesFoldable(pred, ICI->getPredicate()))
2972 return (ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS ||
2973 ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS);
2976 Instruction *apply(Instruction &Log) const {
2977 ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
2978 if (ICI->getOperand(0) != LHS) {
2979 assert(ICI->getOperand(1) == LHS);
2980 ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
2983 ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
2984 unsigned LHSCode = getICmpCode(ICI);
2985 unsigned RHSCode = getICmpCode(RHSICI);
2987 switch (Log.getOpcode()) {
2988 case Instruction::And: Code = LHSCode & RHSCode; break;
2989 case Instruction::Or: Code = LHSCode | RHSCode; break;
2990 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
2991 default: assert(0 && "Illegal logical opcode!"); return 0;
2994 bool isSigned = ICmpInst::isSignedPredicate(RHSICI->getPredicate()) ||
2995 ICmpInst::isSignedPredicate(ICI->getPredicate());
2997 Value *RV = getICmpValue(isSigned, Code, LHS, RHS);
2998 if (Instruction *I = dyn_cast<Instruction>(RV))
3000 // Otherwise, it's a constant boolean value...
3001 return IC.ReplaceInstUsesWith(Log, RV);
3004 } // end anonymous namespace
3006 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
3007 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
3008 // guaranteed to be a binary operator.
3009 Instruction *InstCombiner::OptAndOp(Instruction *Op,
3011 ConstantInt *AndRHS,
3012 BinaryOperator &TheAnd) {
3013 Value *X = Op->getOperand(0);
3014 Constant *Together = 0;
3016 Together = And(AndRHS, OpRHS);
3018 switch (Op->getOpcode()) {
3019 case Instruction::Xor:
3020 if (Op->hasOneUse()) {
3021 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
3022 Instruction *And = BinaryOperator::createAnd(X, AndRHS);
3023 InsertNewInstBefore(And, TheAnd);
3025 return BinaryOperator::createXor(And, Together);
3028 case Instruction::Or:
3029 if (Together == AndRHS) // (X | C) & C --> C
3030 return ReplaceInstUsesWith(TheAnd, AndRHS);
3032 if (Op->hasOneUse() && Together != OpRHS) {
3033 // (X | C1) & C2 --> (X | (C1&C2)) & C2
3034 Instruction *Or = BinaryOperator::createOr(X, Together);
3035 InsertNewInstBefore(Or, TheAnd);
3037 return BinaryOperator::createAnd(Or, AndRHS);
3040 case Instruction::Add:
3041 if (Op->hasOneUse()) {
3042 // Adding a one to a single bit bit-field should be turned into an XOR
3043 // of the bit. First thing to check is to see if this AND is with a
3044 // single bit constant.
3045 const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
3047 // If there is only one bit set...
3048 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
3049 // Ok, at this point, we know that we are masking the result of the
3050 // ADD down to exactly one bit. If the constant we are adding has
3051 // no bits set below this bit, then we can eliminate the ADD.
3052 const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
3054 // Check to see if any bits below the one bit set in AndRHSV are set.
3055 if ((AddRHS & (AndRHSV-1)) == 0) {
3056 // If not, the only thing that can effect the output of the AND is
3057 // the bit specified by AndRHSV. If that bit is set, the effect of
3058 // the XOR is to toggle the bit. If it is clear, then the ADD has
3060 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
3061 TheAnd.setOperand(0, X);
3064 // Pull the XOR out of the AND.
3065 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS);
3066 InsertNewInstBefore(NewAnd, TheAnd);
3067 NewAnd->takeName(Op);
3068 return BinaryOperator::createXor(NewAnd, AndRHS);
3075 case Instruction::Shl: {
3076 // We know that the AND will not produce any of the bits shifted in, so if
3077 // the anded constant includes them, clear them now!
3079 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3080 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3081 APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
3082 ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShlMask);
3084 if (CI->getValue() == ShlMask) {
3085 // Masking out bits that the shift already masks
3086 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
3087 } else if (CI != AndRHS) { // Reducing bits set in and.
3088 TheAnd.setOperand(1, CI);
3093 case Instruction::LShr:
3095 // We know that the AND will not produce any of the bits shifted in, so if
3096 // the anded constant includes them, clear them now! This only applies to
3097 // unsigned shifts, because a signed shr may bring in set bits!
3099 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3100 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3101 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
3102 ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShrMask);
3104 if (CI->getValue() == ShrMask) {
3105 // Masking out bits that the shift already masks.
3106 return ReplaceInstUsesWith(TheAnd, Op);
3107 } else if (CI != AndRHS) {
3108 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
3113 case Instruction::AShr:
3115 // See if this is shifting in some sign extension, then masking it out
3117 if (Op->hasOneUse()) {
3118 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3119 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3120 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
3121 Constant *C = ConstantInt::get(AndRHS->getValue() & ShrMask);
3122 if (C == AndRHS) { // Masking out bits shifted in.
3123 // (Val ashr C1) & C2 -> (Val lshr C1) & C2
3124 // Make the argument unsigned.
3125 Value *ShVal = Op->getOperand(0);
3126 ShVal = InsertNewInstBefore(
3127 BinaryOperator::createLShr(ShVal, OpRHS,
3128 Op->getName()), TheAnd);
3129 return BinaryOperator::createAnd(ShVal, AndRHS, TheAnd.getName());
3138 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
3139 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
3140 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
3141 /// whether to treat the V, Lo and HI as signed or not. IB is the location to
3142 /// insert new instructions.
3143 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
3144 bool isSigned, bool Inside,
3146 assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
3147 ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
3148 "Lo is not <= Hi in range emission code!");
3151 if (Lo == Hi) // Trivially false.
3152 return new ICmpInst(ICmpInst::ICMP_NE, V, V);
3154 // V >= Min && V < Hi --> V < Hi
3155 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
3156 ICmpInst::Predicate pred = (isSigned ?
3157 ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
3158 return new ICmpInst(pred, V, Hi);
3161 // Emit V-Lo <u Hi-Lo
3162 Constant *NegLo = ConstantExpr::getNeg(Lo);
3163 Instruction *Add = BinaryOperator::createAdd(V, NegLo, V->getName()+".off");
3164 InsertNewInstBefore(Add, IB);
3165 Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
3166 return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
3169 if (Lo == Hi) // Trivially true.
3170 return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
3172 // V < Min || V >= Hi -> V > Hi-1
3173 Hi = SubOne(cast<ConstantInt>(Hi));
3174 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
3175 ICmpInst::Predicate pred = (isSigned ?
3176 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
3177 return new ICmpInst(pred, V, Hi);
3180 // Emit V-Lo >u Hi-1-Lo
3181 // Note that Hi has already had one subtracted from it, above.
3182 ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
3183 Instruction *Add = BinaryOperator::createAdd(V, NegLo, V->getName()+".off");
3184 InsertNewInstBefore(Add, IB);
3185 Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
3186 return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
3189 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
3190 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
3191 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
3192 // not, since all 1s are not contiguous.
3193 static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
3194 const APInt& V = Val->getValue();
3195 uint32_t BitWidth = Val->getType()->getBitWidth();
3196 if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
3198 // look for the first zero bit after the run of ones
3199 MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
3200 // look for the first non-zero bit
3201 ME = V.getActiveBits();
3205 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
3206 /// where isSub determines whether the operator is a sub. If we can fold one of
3207 /// the following xforms:
3209 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
3210 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
3211 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
3213 /// return (A +/- B).
3215 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
3216 ConstantInt *Mask, bool isSub,
3218 Instruction *LHSI = dyn_cast<Instruction>(LHS);
3219 if (!LHSI || LHSI->getNumOperands() != 2 ||
3220 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
3222 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
3224 switch (LHSI->getOpcode()) {
3226 case Instruction::And:
3227 if (And(N, Mask) == Mask) {
3228 // If the AndRHS is a power of two minus one (0+1+), this is simple.
3229 if ((Mask->getValue().countLeadingZeros() +
3230 Mask->getValue().countPopulation()) ==
3231 Mask->getValue().getBitWidth())
3234 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
3235 // part, we don't need any explicit masks to take them out of A. If that
3236 // is all N is, ignore it.
3237 uint32_t MB = 0, ME = 0;
3238 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
3239 uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
3240 APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
3241 if (MaskedValueIsZero(RHS, Mask))
3246 case Instruction::Or:
3247 case Instruction::Xor:
3248 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
3249 if ((Mask->getValue().countLeadingZeros() +
3250 Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
3251 && And(N, Mask)->isZero())
3258 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
3260 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
3261 return InsertNewInstBefore(New, I);
3264 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
3265 bool Changed = SimplifyCommutative(I);
3266 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3268 if (isa<UndefValue>(Op1)) // X & undef -> 0
3269 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3273 return ReplaceInstUsesWith(I, Op1);
3275 // See if we can simplify any instructions used by the instruction whose sole
3276 // purpose is to compute bits we don't care about.
3277 if (!isa<VectorType>(I.getType())) {
3278 uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
3279 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
3280 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
3281 KnownZero, KnownOne))
3284 if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
3285 if (CP->isAllOnesValue()) // X & <-1,-1> -> X
3286 return ReplaceInstUsesWith(I, I.getOperand(0));
3287 } else if (isa<ConstantAggregateZero>(Op1)) {
3288 return ReplaceInstUsesWith(I, Op1); // X & <0,0> -> <0,0>
3292 if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
3293 const APInt& AndRHSMask = AndRHS->getValue();
3294 APInt NotAndRHS(~AndRHSMask);
3296 // Optimize a variety of ((val OP C1) & C2) combinations...
3297 if (isa<BinaryOperator>(Op0)) {
3298 Instruction *Op0I = cast<Instruction>(Op0);
3299 Value *Op0LHS = Op0I->getOperand(0);
3300 Value *Op0RHS = Op0I->getOperand(1);
3301 switch (Op0I->getOpcode()) {
3302 case Instruction::Xor:
3303 case Instruction::Or:
3304 // If the mask is only needed on one incoming arm, push it up.
3305 if (Op0I->hasOneUse()) {
3306 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
3307 // Not masking anything out for the LHS, move to RHS.
3308 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
3309 Op0RHS->getName()+".masked");
3310 InsertNewInstBefore(NewRHS, I);
3311 return BinaryOperator::create(
3312 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
3314 if (!isa<Constant>(Op0RHS) &&
3315 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
3316 // Not masking anything out for the RHS, move to LHS.
3317 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
3318 Op0LHS->getName()+".masked");
3319 InsertNewInstBefore(NewLHS, I);
3320 return BinaryOperator::create(
3321 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
3326 case Instruction::Add:
3327 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
3328 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
3329 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
3330 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
3331 return BinaryOperator::createAnd(V, AndRHS);
3332 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
3333 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
3336 case Instruction::Sub:
3337 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
3338 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
3339 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
3340 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
3341 return BinaryOperator::createAnd(V, AndRHS);
3345 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
3346 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
3348 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3349 // If this is an integer truncation or change from signed-to-unsigned, and
3350 // if the source is an and/or with immediate, transform it. This
3351 // frequently occurs for bitfield accesses.
3352 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
3353 if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
3354 CastOp->getNumOperands() == 2)
3355 if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1)))
3356 if (CastOp->getOpcode() == Instruction::And) {
3357 // Change: and (cast (and X, C1) to T), C2
3358 // into : and (cast X to T), trunc_or_bitcast(C1)&C2
3359 // This will fold the two constants together, which may allow
3360 // other simplifications.
3361 Instruction *NewCast = CastInst::createTruncOrBitCast(
3362 CastOp->getOperand(0), I.getType(),
3363 CastOp->getName()+".shrunk");
3364 NewCast = InsertNewInstBefore(NewCast, I);
3365 // trunc_or_bitcast(C1)&C2
3366 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
3367 C3 = ConstantExpr::getAnd(C3, AndRHS);
3368 return BinaryOperator::createAnd(NewCast, C3);
3369 } else if (CastOp->getOpcode() == Instruction::Or) {
3370 // Change: and (cast (or X, C1) to T), C2
3371 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
3372 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
3373 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
3374 return ReplaceInstUsesWith(I, AndRHS);
3379 // Try to fold constant and into select arguments.
3380 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3381 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3383 if (isa<PHINode>(Op0))
3384 if (Instruction *NV = FoldOpIntoPhi(I))
3388 Value *Op0NotVal = dyn_castNotVal(Op0);
3389 Value *Op1NotVal = dyn_castNotVal(Op1);
3391 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
3392 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3394 // (~A & ~B) == (~(A | B)) - De Morgan's Law
3395 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
3396 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
3397 I.getName()+".demorgan");
3398 InsertNewInstBefore(Or, I);
3399 return BinaryOperator::createNot(Or);
3403 Value *A = 0, *B = 0, *C = 0, *D = 0;
3404 if (match(Op0, m_Or(m_Value(A), m_Value(B)))) {
3405 if (A == Op1 || B == Op1) // (A | ?) & A --> A
3406 return ReplaceInstUsesWith(I, Op1);
3408 // (A|B) & ~(A&B) -> A^B
3409 if (match(Op1, m_Not(m_And(m_Value(C), m_Value(D))))) {
3410 if ((A == C && B == D) || (A == D && B == C))
3411 return BinaryOperator::createXor(A, B);
3415 if (match(Op1, m_Or(m_Value(A), m_Value(B)))) {
3416 if (A == Op0 || B == Op0) // A & (A | ?) --> A
3417 return ReplaceInstUsesWith(I, Op0);
3419 // ~(A&B) & (A|B) -> A^B
3420 if (match(Op0, m_Not(m_And(m_Value(C), m_Value(D))))) {
3421 if ((A == C && B == D) || (A == D && B == C))
3422 return BinaryOperator::createXor(A, B);
3426 if (Op0->hasOneUse() &&
3427 match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
3428 if (A == Op1) { // (A^B)&A -> A&(A^B)
3429 I.swapOperands(); // Simplify below
3430 std::swap(Op0, Op1);
3431 } else if (B == Op1) { // (A^B)&B -> B&(B^A)
3432 cast<BinaryOperator>(Op0)->swapOperands();
3433 I.swapOperands(); // Simplify below
3434 std::swap(Op0, Op1);
3437 if (Op1->hasOneUse() &&
3438 match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
3439 if (B == Op0) { // B&(A^B) -> B&(B^A)
3440 cast<BinaryOperator>(Op1)->swapOperands();
3443 if (A == Op0) { // A&(A^B) -> A & ~B
3444 Instruction *NotB = BinaryOperator::createNot(B, "tmp");
3445 InsertNewInstBefore(NotB, I);
3446 return BinaryOperator::createAnd(A, NotB);
3451 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
3452 // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
3453 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
3456 Value *LHSVal, *RHSVal;
3457 ConstantInt *LHSCst, *RHSCst;
3458 ICmpInst::Predicate LHSCC, RHSCC;
3459 if (match(Op0, m_ICmp(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
3460 if (match(RHS, m_ICmp(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
3461 if (LHSVal == RHSVal && // Found (X icmp C1) & (X icmp C2)
3462 // ICMP_[GL]E X, CST is folded to ICMP_[GL]T elsewhere.
3463 LHSCC != ICmpInst::ICMP_UGE && LHSCC != ICmpInst::ICMP_ULE &&
3464 RHSCC != ICmpInst::ICMP_UGE && RHSCC != ICmpInst::ICMP_ULE &&
3465 LHSCC != ICmpInst::ICMP_SGE && LHSCC != ICmpInst::ICMP_SLE &&
3466 RHSCC != ICmpInst::ICMP_SGE && RHSCC != ICmpInst::ICMP_SLE) {
3467 // Ensure that the larger constant is on the RHS.
3468 ICmpInst::Predicate GT = ICmpInst::isSignedPredicate(LHSCC) ?
3469 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
3470 Constant *Cmp = ConstantExpr::getICmp(GT, LHSCst, RHSCst);
3471 ICmpInst *LHS = cast<ICmpInst>(Op0);
3472 if (cast<ConstantInt>(Cmp)->getZExtValue()) {
3473 std::swap(LHS, RHS);
3474 std::swap(LHSCst, RHSCst);
3475 std::swap(LHSCC, RHSCC);
3478 // At this point, we know we have have two icmp instructions
3479 // comparing a value against two constants and and'ing the result
3480 // together. Because of the above check, we know that we only have
3481 // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
3482 // (from the FoldICmpLogical check above), that the two constants
3483 // are not equal and that the larger constant is on the RHS
3484 assert(LHSCst != RHSCst && "Compares not folded above?");
3487 default: assert(0 && "Unknown integer condition code!");
3488 case ICmpInst::ICMP_EQ:
3490 default: assert(0 && "Unknown integer condition code!");
3491 case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
3492 case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
3493 case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
3494 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
3495 case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
3496 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
3497 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
3498 return ReplaceInstUsesWith(I, LHS);
3500 case ICmpInst::ICMP_NE:
3502 default: assert(0 && "Unknown integer condition code!");
3503 case ICmpInst::ICMP_ULT:
3504 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
3505 return new ICmpInst(ICmpInst::ICMP_ULT, LHSVal, LHSCst);
3506 break; // (X != 13 & X u< 15) -> no change
3507 case ICmpInst::ICMP_SLT:
3508 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
3509 return new ICmpInst(ICmpInst::ICMP_SLT, LHSVal, LHSCst);
3510 break; // (X != 13 & X s< 15) -> no change
3511 case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
3512 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
3513 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
3514 return ReplaceInstUsesWith(I, RHS);
3515 case ICmpInst::ICMP_NE:
3516 if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
3517 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
3518 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
3519 LHSVal->getName()+".off");
3520 InsertNewInstBefore(Add, I);
3521 return new ICmpInst(ICmpInst::ICMP_UGT, Add,
3522 ConstantInt::get(Add->getType(), 1));
3524 break; // (X != 13 & X != 15) -> no change
3527 case ICmpInst::ICMP_ULT:
3529 default: assert(0 && "Unknown integer condition code!");
3530 case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
3531 case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
3532 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
3533 case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
3535 case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
3536 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
3537 return ReplaceInstUsesWith(I, LHS);
3538 case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
3542 case ICmpInst::ICMP_SLT:
3544 default: assert(0 && "Unknown integer condition code!");
3545 case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
3546 case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
3547 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
3548 case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
3550 case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
3551 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
3552 return ReplaceInstUsesWith(I, LHS);
3553 case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
3557 case ICmpInst::ICMP_UGT:
3559 default: assert(0 && "Unknown integer condition code!");
3560 case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X > 13
3561 return ReplaceInstUsesWith(I, LHS);
3562 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
3563 return ReplaceInstUsesWith(I, RHS);
3564 case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
3566 case ICmpInst::ICMP_NE:
3567 if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
3568 return new ICmpInst(LHSCC, LHSVal, RHSCst);
3569 break; // (X u> 13 & X != 15) -> no change
3570 case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) ->(X-14) <u 1
3571 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, false,
3573 case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
3577 case ICmpInst::ICMP_SGT:
3579 default: assert(0 && "Unknown integer condition code!");
3580 case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X s> 13
3581 return ReplaceInstUsesWith(I, LHS);
3582 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
3583 return ReplaceInstUsesWith(I, RHS);
3584 case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
3586 case ICmpInst::ICMP_NE:
3587 if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
3588 return new ICmpInst(LHSCC, LHSVal, RHSCst);
3589 break; // (X s> 13 & X != 15) -> no change
3590 case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) ->(X-14) s< 1
3591 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true,
3593 case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
3601 // fold (and (cast A), (cast B)) -> (cast (and A, B))
3602 if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
3603 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
3604 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
3605 const Type *SrcTy = Op0C->getOperand(0)->getType();
3606 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
3607 // Only do this if the casts both really cause code to be generated.
3608 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
3610 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
3612 Instruction *NewOp = BinaryOperator::createAnd(Op0C->getOperand(0),
3613 Op1C->getOperand(0),
3615 InsertNewInstBefore(NewOp, I);
3616 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
3620 // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
3621 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
3622 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
3623 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
3624 SI0->getOperand(1) == SI1->getOperand(1) &&
3625 (SI0->hasOneUse() || SI1->hasOneUse())) {
3626 Instruction *NewOp =
3627 InsertNewInstBefore(BinaryOperator::createAnd(SI0->getOperand(0),
3629 SI0->getName()), I);
3630 return BinaryOperator::create(SI1->getOpcode(), NewOp,
3631 SI1->getOperand(1));
3635 // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
3636 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
3637 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) {
3638 if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
3639 RHS->getPredicate() == FCmpInst::FCMP_ORD)
3640 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
3641 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
3642 // If either of the constants are nans, then the whole thing returns
3644 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
3645 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
3646 return new FCmpInst(FCmpInst::FCMP_ORD, LHS->getOperand(0),
3647 RHS->getOperand(0));
3652 return Changed ? &I : 0;
3655 /// CollectBSwapParts - Look to see if the specified value defines a single byte
3656 /// in the result. If it does, and if the specified byte hasn't been filled in
3657 /// yet, fill it in and return false.
3658 static bool CollectBSwapParts(Value *V, SmallVector<Value*, 8> &ByteValues) {
3659 Instruction *I = dyn_cast<Instruction>(V);
3660 if (I == 0) return true;
3662 // If this is an or instruction, it is an inner node of the bswap.
3663 if (I->getOpcode() == Instruction::Or)
3664 return CollectBSwapParts(I->getOperand(0), ByteValues) ||
3665 CollectBSwapParts(I->getOperand(1), ByteValues);
3667 uint32_t BitWidth = I->getType()->getPrimitiveSizeInBits();
3668 // If this is a shift by a constant int, and it is "24", then its operand
3669 // defines a byte. We only handle unsigned types here.
3670 if (I->isShift() && isa<ConstantInt>(I->getOperand(1))) {
3671 // Not shifting the entire input by N-1 bytes?
3672 if (cast<ConstantInt>(I->getOperand(1))->getLimitedValue(BitWidth) !=
3673 8*(ByteValues.size()-1))
3677 if (I->getOpcode() == Instruction::Shl) {
3678 // X << 24 defines the top byte with the lowest of the input bytes.
3679 DestNo = ByteValues.size()-1;
3681 // X >>u 24 defines the low byte with the highest of the input bytes.
3685 // If the destination byte value is already defined, the values are or'd
3686 // together, which isn't a bswap (unless it's an or of the same bits).
3687 if (ByteValues[DestNo] && ByteValues[DestNo] != I->getOperand(0))
3689 ByteValues[DestNo] = I->getOperand(0);
3693 // Otherwise, we can only handle and(shift X, imm), imm). Bail out of if we
3695 Value *Shift = 0, *ShiftLHS = 0;
3696 ConstantInt *AndAmt = 0, *ShiftAmt = 0;
3697 if (!match(I, m_And(m_Value(Shift), m_ConstantInt(AndAmt))) ||
3698 !match(Shift, m_Shift(m_Value(ShiftLHS), m_ConstantInt(ShiftAmt))))
3700 Instruction *SI = cast<Instruction>(Shift);
3702 // Make sure that the shift amount is by a multiple of 8 and isn't too big.
3703 if (ShiftAmt->getLimitedValue(BitWidth) & 7 ||
3704 ShiftAmt->getLimitedValue(BitWidth) > 8*ByteValues.size())
3707 // Turn 0xFF -> 0, 0xFF00 -> 1, 0xFF0000 -> 2, etc.
3709 if (AndAmt->getValue().getActiveBits() > 64)
3711 uint64_t AndAmtVal = AndAmt->getZExtValue();
3712 for (DestByte = 0; DestByte != ByteValues.size(); ++DestByte)
3713 if (AndAmtVal == uint64_t(0xFF) << 8*DestByte)
3715 // Unknown mask for bswap.
3716 if (DestByte == ByteValues.size()) return true;
3718 unsigned ShiftBytes = ShiftAmt->getZExtValue()/8;
3720 if (SI->getOpcode() == Instruction::Shl)
3721 SrcByte = DestByte - ShiftBytes;
3723 SrcByte = DestByte + ShiftBytes;
3725 // If the SrcByte isn't a bswapped value from the DestByte, reject it.
3726 if (SrcByte != ByteValues.size()-DestByte-1)
3729 // If the destination byte value is already defined, the values are or'd
3730 // together, which isn't a bswap (unless it's an or of the same bits).
3731 if (ByteValues[DestByte] && ByteValues[DestByte] != SI->getOperand(0))
3733 ByteValues[DestByte] = SI->getOperand(0);
3737 /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
3738 /// If so, insert the new bswap intrinsic and return it.
3739 Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
3740 const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
3741 if (!ITy || ITy->getBitWidth() % 16)
3742 return 0; // Can only bswap pairs of bytes. Can't do vectors.
3744 /// ByteValues - For each byte of the result, we keep track of which value
3745 /// defines each byte.
3746 SmallVector<Value*, 8> ByteValues;
3747 ByteValues.resize(ITy->getBitWidth()/8);
3749 // Try to find all the pieces corresponding to the bswap.
3750 if (CollectBSwapParts(I.getOperand(0), ByteValues) ||
3751 CollectBSwapParts(I.getOperand(1), ByteValues))
3754 // Check to see if all of the bytes come from the same value.
3755 Value *V = ByteValues[0];
3756 if (V == 0) return 0; // Didn't find a byte? Must be zero.
3758 // Check to make sure that all of the bytes come from the same value.
3759 for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
3760 if (ByteValues[i] != V)
3762 const Type *Tys[] = { ITy };
3763 Module *M = I.getParent()->getParent()->getParent();
3764 Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
3765 return new CallInst(F, V);
3769 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
3770 bool Changed = SimplifyCommutative(I);
3771 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3773 if (isa<UndefValue>(Op1)) // X | undef -> -1
3774 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
3778 return ReplaceInstUsesWith(I, Op0);
3780 // See if we can simplify any instructions used by the instruction whose sole
3781 // purpose is to compute bits we don't care about.
3782 if (!isa<VectorType>(I.getType())) {
3783 uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
3784 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
3785 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
3786 KnownZero, KnownOne))
3788 } else if (isa<ConstantAggregateZero>(Op1)) {
3789 return ReplaceInstUsesWith(I, Op0); // X | <0,0> -> X
3790 } else if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
3791 if (CP->isAllOnesValue()) // X | <-1,-1> -> <-1,-1>
3792 return ReplaceInstUsesWith(I, I.getOperand(1));
3798 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3799 ConstantInt *C1 = 0; Value *X = 0;
3800 // (X & C1) | C2 --> (X | C2) & (C1|C2)
3801 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
3802 Instruction *Or = BinaryOperator::createOr(X, RHS);
3803 InsertNewInstBefore(Or, I);
3805 return BinaryOperator::createAnd(Or,
3806 ConstantInt::get(RHS->getValue() | C1->getValue()));
3809 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
3810 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
3811 Instruction *Or = BinaryOperator::createOr(X, RHS);
3812 InsertNewInstBefore(Or, I);
3814 return BinaryOperator::createXor(Or,
3815 ConstantInt::get(C1->getValue() & ~RHS->getValue()));
3818 // Try to fold constant and into select arguments.
3819 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3820 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3822 if (isa<PHINode>(Op0))
3823 if (Instruction *NV = FoldOpIntoPhi(I))
3827 Value *A = 0, *B = 0;
3828 ConstantInt *C1 = 0, *C2 = 0;
3830 if (match(Op0, m_And(m_Value(A), m_Value(B))))
3831 if (A == Op1 || B == Op1) // (A & ?) | A --> A
3832 return ReplaceInstUsesWith(I, Op1);
3833 if (match(Op1, m_And(m_Value(A), m_Value(B))))
3834 if (A == Op0 || B == Op0) // A | (A & ?) --> A
3835 return ReplaceInstUsesWith(I, Op0);
3837 // (A | B) | C and A | (B | C) -> bswap if possible.
3838 // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
3839 if (match(Op0, m_Or(m_Value(), m_Value())) ||
3840 match(Op1, m_Or(m_Value(), m_Value())) ||
3841 (match(Op0, m_Shift(m_Value(), m_Value())) &&
3842 match(Op1, m_Shift(m_Value(), m_Value())))) {
3843 if (Instruction *BSwap = MatchBSwap(I))
3847 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
3848 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
3849 MaskedValueIsZero(Op1, C1->getValue())) {
3850 Instruction *NOr = BinaryOperator::createOr(A, Op1);
3851 InsertNewInstBefore(NOr, I);
3853 return BinaryOperator::createXor(NOr, C1);
3856 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
3857 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
3858 MaskedValueIsZero(Op0, C1->getValue())) {
3859 Instruction *NOr = BinaryOperator::createOr(A, Op0);
3860 InsertNewInstBefore(NOr, I);
3862 return BinaryOperator::createXor(NOr, C1);
3866 Value *C = 0, *D = 0;
3867 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
3868 match(Op1, m_And(m_Value(B), m_Value(D)))) {
3869 Value *V1 = 0, *V2 = 0, *V3 = 0;
3870 C1 = dyn_cast<ConstantInt>(C);
3871 C2 = dyn_cast<ConstantInt>(D);
3872 if (C1 && C2) { // (A & C1)|(B & C2)
3873 // If we have: ((V + N) & C1) | (V & C2)
3874 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
3875 // replace with V+N.
3876 if (C1->getValue() == ~C2->getValue()) {
3877 if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
3878 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
3879 // Add commutes, try both ways.
3880 if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
3881 return ReplaceInstUsesWith(I, A);
3882 if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
3883 return ReplaceInstUsesWith(I, A);
3885 // Or commutes, try both ways.
3886 if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
3887 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
3888 // Add commutes, try both ways.
3889 if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
3890 return ReplaceInstUsesWith(I, B);
3891 if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
3892 return ReplaceInstUsesWith(I, B);
3895 V1 = 0; V2 = 0; V3 = 0;
3898 // Check to see if we have any common things being and'ed. If so, find the
3899 // terms for V1 & (V2|V3).
3900 if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
3901 if (A == B) // (A & C)|(A & D) == A & (C|D)
3902 V1 = A, V2 = C, V3 = D;
3903 else if (A == D) // (A & C)|(B & A) == A & (B|C)
3904 V1 = A, V2 = B, V3 = C;
3905 else if (C == B) // (A & C)|(C & D) == C & (A|D)
3906 V1 = C, V2 = A, V3 = D;
3907 else if (C == D) // (A & C)|(B & C) == C & (A|B)
3908 V1 = C, V2 = A, V3 = B;
3912 InsertNewInstBefore(BinaryOperator::createOr(V2, V3, "tmp"), I);
3913 return BinaryOperator::createAnd(V1, Or);
3918 // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
3919 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
3920 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
3921 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
3922 SI0->getOperand(1) == SI1->getOperand(1) &&
3923 (SI0->hasOneUse() || SI1->hasOneUse())) {
3924 Instruction *NewOp =
3925 InsertNewInstBefore(BinaryOperator::createOr(SI0->getOperand(0),
3927 SI0->getName()), I);
3928 return BinaryOperator::create(SI1->getOpcode(), NewOp,
3929 SI1->getOperand(1));
3933 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
3934 if (A == Op1) // ~A | A == -1
3935 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
3939 // Note, A is still live here!
3940 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
3942 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
3944 // (~A | ~B) == (~(A & B)) - De Morgan's Law
3945 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
3946 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
3947 I.getName()+".demorgan"), I);
3948 return BinaryOperator::createNot(And);
3952 // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
3953 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
3954 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
3957 Value *LHSVal, *RHSVal;
3958 ConstantInt *LHSCst, *RHSCst;
3959 ICmpInst::Predicate LHSCC, RHSCC;
3960 if (match(Op0, m_ICmp(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
3961 if (match(RHS, m_ICmp(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
3962 if (LHSVal == RHSVal && // Found (X icmp C1) | (X icmp C2)
3963 // icmp [us][gl]e x, cst is folded to icmp [us][gl]t elsewhere.
3964 LHSCC != ICmpInst::ICMP_UGE && LHSCC != ICmpInst::ICMP_ULE &&
3965 RHSCC != ICmpInst::ICMP_UGE && RHSCC != ICmpInst::ICMP_ULE &&
3966 LHSCC != ICmpInst::ICMP_SGE && LHSCC != ICmpInst::ICMP_SLE &&
3967 RHSCC != ICmpInst::ICMP_SGE && RHSCC != ICmpInst::ICMP_SLE &&
3968 // We can't fold (ugt x, C) | (sgt x, C2).
3969 PredicatesFoldable(LHSCC, RHSCC)) {
3970 // Ensure that the larger constant is on the RHS.
3971 ICmpInst *LHS = cast<ICmpInst>(Op0);
3973 if (ICmpInst::isSignedPredicate(LHSCC))
3974 NeedsSwap = LHSCst->getValue().sgt(RHSCst->getValue());
3976 NeedsSwap = LHSCst->getValue().ugt(RHSCst->getValue());
3979 std::swap(LHS, RHS);
3980 std::swap(LHSCst, RHSCst);
3981 std::swap(LHSCC, RHSCC);
3984 // At this point, we know we have have two icmp instructions
3985 // comparing a value against two constants and or'ing the result
3986 // together. Because of the above check, we know that we only have
3987 // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
3988 // FoldICmpLogical check above), that the two constants are not
3990 assert(LHSCst != RHSCst && "Compares not folded above?");
3993 default: assert(0 && "Unknown integer condition code!");
3994 case ICmpInst::ICMP_EQ:
3996 default: assert(0 && "Unknown integer condition code!");
3997 case ICmpInst::ICMP_EQ:
3998 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
3999 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
4000 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
4001 LHSVal->getName()+".off");
4002 InsertNewInstBefore(Add, I);
4003 AddCST = Subtract(AddOne(RHSCst), LHSCst);
4004 return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
4006 break; // (X == 13 | X == 15) -> no change
4007 case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
4008 case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
4010 case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
4011 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
4012 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
4013 return ReplaceInstUsesWith(I, RHS);
4016 case ICmpInst::ICMP_NE:
4018 default: assert(0 && "Unknown integer condition code!");
4019 case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
4020 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
4021 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
4022 return ReplaceInstUsesWith(I, LHS);
4023 case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
4024 case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
4025 case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
4026 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4029 case ICmpInst::ICMP_ULT:
4031 default: assert(0 && "Unknown integer condition code!");
4032 case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
4034 case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) ->(X-13) u> 2
4035 // If RHSCst is [us]MAXINT, it is always false. Not handling
4036 // this can cause overflow.
4037 if (RHSCst->isMaxValue(false))
4038 return ReplaceInstUsesWith(I, LHS);
4039 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false,
4041 case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
4043 case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
4044 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
4045 return ReplaceInstUsesWith(I, RHS);
4046 case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
4050 case ICmpInst::ICMP_SLT:
4052 default: assert(0 && "Unknown integer condition code!");
4053 case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
4055 case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) ->(X-13) s> 2
4056 // If RHSCst is [us]MAXINT, it is always false. Not handling
4057 // this can cause overflow.
4058 if (RHSCst->isMaxValue(true))
4059 return ReplaceInstUsesWith(I, LHS);
4060 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), true,
4062 case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
4064 case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
4065 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
4066 return ReplaceInstUsesWith(I, RHS);
4067 case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
4071 case ICmpInst::ICMP_UGT:
4073 default: assert(0 && "Unknown integer condition code!");
4074 case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
4075 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
4076 return ReplaceInstUsesWith(I, LHS);
4077 case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
4079 case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
4080 case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
4081 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4082 case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
4086 case ICmpInst::ICMP_SGT:
4088 default: assert(0 && "Unknown integer condition code!");
4089 case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
4090 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
4091 return ReplaceInstUsesWith(I, LHS);
4092 case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
4094 case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
4095 case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
4096 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4097 case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
4105 // fold (or (cast A), (cast B)) -> (cast (or A, B))
4106 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
4107 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
4108 if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
4109 const Type *SrcTy = Op0C->getOperand(0)->getType();
4110 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
4111 // Only do this if the casts both really cause code to be generated.
4112 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
4114 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
4116 Instruction *NewOp = BinaryOperator::createOr(Op0C->getOperand(0),
4117 Op1C->getOperand(0),
4119 InsertNewInstBefore(NewOp, I);
4120 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
4126 // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
4127 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
4128 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) {
4129 if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
4130 RHS->getPredicate() == FCmpInst::FCMP_UNO)
4131 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
4132 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
4133 // If either of the constants are nans, then the whole thing returns
4135 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
4136 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4138 // Otherwise, no need to compare the two constants, compare the
4140 return new FCmpInst(FCmpInst::FCMP_UNO, LHS->getOperand(0),
4141 RHS->getOperand(0));
4146 return Changed ? &I : 0;
4149 // XorSelf - Implements: X ^ X --> 0
4152 XorSelf(Value *rhs) : RHS(rhs) {}
4153 bool shouldApply(Value *LHS) const { return LHS == RHS; }
4154 Instruction *apply(BinaryOperator &Xor) const {
4160 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
4161 bool Changed = SimplifyCommutative(I);
4162 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4164 if (isa<UndefValue>(Op1))
4165 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
4167 // xor X, X = 0, even if X is nested in a sequence of Xor's.
4168 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
4169 assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
4170 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4173 // See if we can simplify any instructions used by the instruction whose sole
4174 // purpose is to compute bits we don't care about.
4175 if (!isa<VectorType>(I.getType())) {
4176 uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
4177 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
4178 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
4179 KnownZero, KnownOne))
4181 } else if (isa<ConstantAggregateZero>(Op1)) {
4182 return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X
4185 // Is this a ~ operation?
4186 if (Value *NotOp = dyn_castNotVal(&I)) {
4187 // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
4188 // ~(~X | Y) === (X & ~Y) - De Morgan's Law
4189 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
4190 if (Op0I->getOpcode() == Instruction::And ||
4191 Op0I->getOpcode() == Instruction::Or) {
4192 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
4193 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
4195 BinaryOperator::createNot(Op0I->getOperand(1),
4196 Op0I->getOperand(1)->getName()+".not");
4197 InsertNewInstBefore(NotY, I);
4198 if (Op0I->getOpcode() == Instruction::And)
4199 return BinaryOperator::createOr(Op0NotVal, NotY);
4201 return BinaryOperator::createAnd(Op0NotVal, NotY);
4208 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
4209 // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
4210 if (RHS == ConstantInt::getTrue() && Op0->hasOneUse()) {
4211 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
4212 return new ICmpInst(ICI->getInversePredicate(),
4213 ICI->getOperand(0), ICI->getOperand(1));
4215 if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
4216 return new FCmpInst(FCI->getInversePredicate(),
4217 FCI->getOperand(0), FCI->getOperand(1));
4220 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
4221 // ~(c-X) == X-c-1 == X+(-c-1)
4222 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
4223 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
4224 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
4225 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
4226 ConstantInt::get(I.getType(), 1));
4227 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
4230 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
4231 if (Op0I->getOpcode() == Instruction::Add) {
4232 // ~(X-c) --> (-c-1)-X
4233 if (RHS->isAllOnesValue()) {
4234 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
4235 return BinaryOperator::createSub(
4236 ConstantExpr::getSub(NegOp0CI,
4237 ConstantInt::get(I.getType(), 1)),
4238 Op0I->getOperand(0));
4239 } else if (RHS->getValue().isSignBit()) {
4240 // (X + C) ^ signbit -> (X + C + signbit)
4241 Constant *C = ConstantInt::get(RHS->getValue() + Op0CI->getValue());
4242 return BinaryOperator::createAdd(Op0I->getOperand(0), C);
4245 } else if (Op0I->getOpcode() == Instruction::Or) {
4246 // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
4247 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
4248 Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
4249 // Anything in both C1 and C2 is known to be zero, remove it from
4251 Constant *CommonBits = And(Op0CI, RHS);
4252 NewRHS = ConstantExpr::getAnd(NewRHS,
4253 ConstantExpr::getNot(CommonBits));
4254 AddToWorkList(Op0I);
4255 I.setOperand(0, Op0I->getOperand(0));
4256 I.setOperand(1, NewRHS);
4262 // Try to fold constant and into select arguments.
4263 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
4264 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
4266 if (isa<PHINode>(Op0))
4267 if (Instruction *NV = FoldOpIntoPhi(I))
4271 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
4273 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
4275 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
4277 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
4280 BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
4283 if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
4284 if (A == Op0) { // B^(B|A) == (A|B)^B
4285 Op1I->swapOperands();
4287 std::swap(Op0, Op1);
4288 } else if (B == Op0) { // B^(A|B) == (A|B)^B
4289 I.swapOperands(); // Simplified below.
4290 std::swap(Op0, Op1);
4292 } else if (match(Op1I, m_Xor(m_Value(A), m_Value(B)))) {
4293 if (Op0 == A) // A^(A^B) == B
4294 return ReplaceInstUsesWith(I, B);
4295 else if (Op0 == B) // A^(B^A) == B
4296 return ReplaceInstUsesWith(I, A);
4297 } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && Op1I->hasOneUse()){
4298 if (A == Op0) { // A^(A&B) -> A^(B&A)
4299 Op1I->swapOperands();
4302 if (B == Op0) { // A^(B&A) -> (B&A)^A
4303 I.swapOperands(); // Simplified below.
4304 std::swap(Op0, Op1);
4309 BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
4312 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && Op0I->hasOneUse()) {
4313 if (A == Op1) // (B|A)^B == (A|B)^B
4315 if (B == Op1) { // (A|B)^B == A & ~B
4317 InsertNewInstBefore(BinaryOperator::createNot(Op1, "tmp"), I);
4318 return BinaryOperator::createAnd(A, NotB);
4320 } else if (match(Op0I, m_Xor(m_Value(A), m_Value(B)))) {
4321 if (Op1 == A) // (A^B)^A == B
4322 return ReplaceInstUsesWith(I, B);
4323 else if (Op1 == B) // (B^A)^A == B
4324 return ReplaceInstUsesWith(I, A);
4325 } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && Op0I->hasOneUse()){
4326 if (A == Op1) // (A&B)^A -> (B&A)^A
4328 if (B == Op1 && // (B&A)^A == ~B & A
4329 !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
4331 InsertNewInstBefore(BinaryOperator::createNot(A, "tmp"), I);
4332 return BinaryOperator::createAnd(N, Op1);
4337 // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
4338 if (Op0I && Op1I && Op0I->isShift() &&
4339 Op0I->getOpcode() == Op1I->getOpcode() &&
4340 Op0I->getOperand(1) == Op1I->getOperand(1) &&
4341 (Op1I->hasOneUse() || Op1I->hasOneUse())) {
4342 Instruction *NewOp =
4343 InsertNewInstBefore(BinaryOperator::createXor(Op0I->getOperand(0),
4344 Op1I->getOperand(0),
4345 Op0I->getName()), I);
4346 return BinaryOperator::create(Op1I->getOpcode(), NewOp,
4347 Op1I->getOperand(1));
4351 Value *A, *B, *C, *D;
4352 // (A & B)^(A | B) -> A ^ B
4353 if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
4354 match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
4355 if ((A == C && B == D) || (A == D && B == C))
4356 return BinaryOperator::createXor(A, B);
4358 // (A | B)^(A & B) -> A ^ B
4359 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
4360 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
4361 if ((A == C && B == D) || (A == D && B == C))
4362 return BinaryOperator::createXor(A, B);
4366 if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
4367 match(Op0I, m_And(m_Value(A), m_Value(B))) &&
4368 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
4369 // (X & Y)^(X & Y) -> (Y^Z) & X
4370 Value *X = 0, *Y = 0, *Z = 0;
4372 X = A, Y = B, Z = D;
4374 X = A, Y = B, Z = C;
4376 X = B, Y = A, Z = D;
4378 X = B, Y = A, Z = C;
4381 Instruction *NewOp =
4382 InsertNewInstBefore(BinaryOperator::createXor(Y, Z, Op0->getName()), I);
4383 return BinaryOperator::createAnd(NewOp, X);
4388 // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
4389 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
4390 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
4393 // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
4394 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
4395 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
4396 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
4397 const Type *SrcTy = Op0C->getOperand(0)->getType();
4398 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
4399 // Only do this if the casts both really cause code to be generated.
4400 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
4402 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
4404 Instruction *NewOp = BinaryOperator::createXor(Op0C->getOperand(0),
4405 Op1C->getOperand(0),
4407 InsertNewInstBefore(NewOp, I);
4408 return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
4412 return Changed ? &I : 0;
4415 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
4416 /// overflowed for this type.
4417 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
4418 ConstantInt *In2, bool IsSigned = false) {
4419 Result = cast<ConstantInt>(Add(In1, In2));
4422 if (In2->getValue().isNegative())
4423 return Result->getValue().sgt(In1->getValue());
4425 return Result->getValue().slt(In1->getValue());
4427 return Result->getValue().ult(In1->getValue());
4430 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
4431 /// code necessary to compute the offset from the base pointer (without adding
4432 /// in the base pointer). Return the result as a signed integer of intptr size.
4433 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
4434 TargetData &TD = IC.getTargetData();
4435 gep_type_iterator GTI = gep_type_begin(GEP);
4436 const Type *IntPtrTy = TD.getIntPtrType();
4437 Value *Result = Constant::getNullValue(IntPtrTy);
4439 // Build a mask for high order bits.
4440 unsigned IntPtrWidth = TD.getPointerSize()*8;
4441 uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
4443 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
4444 Value *Op = GEP->getOperand(i);
4445 uint64_t Size = TD.getABITypeSize(GTI.getIndexedType()) & PtrSizeMask;
4446 if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
4447 if (OpC->isZero()) continue;
4449 // Handle a struct index, which adds its field offset to the pointer.
4450 if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
4451 Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
4453 if (ConstantInt *RC = dyn_cast<ConstantInt>(Result))
4454 Result = ConstantInt::get(RC->getValue() + APInt(IntPtrWidth, Size));
4456 Result = IC.InsertNewInstBefore(
4457 BinaryOperator::createAdd(Result,
4458 ConstantInt::get(IntPtrTy, Size),
4459 GEP->getName()+".offs"), I);
4463 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
4464 Constant *OC = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
4465 Scale = ConstantExpr::getMul(OC, Scale);
4466 if (Constant *RC = dyn_cast<Constant>(Result))
4467 Result = ConstantExpr::getAdd(RC, Scale);
4469 // Emit an add instruction.
4470 Result = IC.InsertNewInstBefore(
4471 BinaryOperator::createAdd(Result, Scale,
4472 GEP->getName()+".offs"), I);
4476 // Convert to correct type.
4477 if (Op->getType() != IntPtrTy) {
4478 if (Constant *OpC = dyn_cast<Constant>(Op))
4479 Op = ConstantExpr::getSExt(OpC, IntPtrTy);
4481 Op = IC.InsertNewInstBefore(new SExtInst(Op, IntPtrTy,
4482 Op->getName()+".c"), I);
4485 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
4486 if (Constant *OpC = dyn_cast<Constant>(Op))
4487 Op = ConstantExpr::getMul(OpC, Scale);
4488 else // We'll let instcombine(mul) convert this to a shl if possible.
4489 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
4490 GEP->getName()+".idx"), I);
4493 // Emit an add instruction.
4494 if (isa<Constant>(Op) && isa<Constant>(Result))
4495 Result = ConstantExpr::getAdd(cast<Constant>(Op),
4496 cast<Constant>(Result));
4498 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
4499 GEP->getName()+".offs"), I);
4504 /// FoldGEPICmp - Fold comparisons between a GEP instruction and something
4505 /// else. At this point we know that the GEP is on the LHS of the comparison.
4506 Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS,
4507 ICmpInst::Predicate Cond,
4509 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
4511 if (CastInst *CI = dyn_cast<CastInst>(RHS))
4512 if (isa<PointerType>(CI->getOperand(0)->getType()))
4513 RHS = CI->getOperand(0);
4515 Value *PtrBase = GEPLHS->getOperand(0);
4516 if (PtrBase == RHS) {
4517 // As an optimization, we don't actually have to compute the actual value of
4518 // OFFSET if this is a icmp_eq or icmp_ne comparison, just return whether
4519 // each index is zero or not.
4520 if (Cond == ICmpInst::ICMP_EQ || Cond == ICmpInst::ICMP_NE) {
4521 Instruction *InVal = 0;
4522 gep_type_iterator GTI = gep_type_begin(GEPLHS);
4523 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
4525 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
4526 if (isa<UndefValue>(C)) // undef index -> undef.
4527 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
4528 if (C->isNullValue())
4530 else if (TD->getABITypeSize(GTI.getIndexedType()) == 0) {
4531 EmitIt = false; // This is indexing into a zero sized array?
4532 } else if (isa<ConstantInt>(C))
4533 return ReplaceInstUsesWith(I, // No comparison is needed here.
4534 ConstantInt::get(Type::Int1Ty,
4535 Cond == ICmpInst::ICMP_NE));
4540 new ICmpInst(Cond, GEPLHS->getOperand(i),
4541 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
4545 InVal = InsertNewInstBefore(InVal, I);
4546 InsertNewInstBefore(Comp, I);
4547 if (Cond == ICmpInst::ICMP_NE) // True if any are unequal
4548 InVal = BinaryOperator::createOr(InVal, Comp);
4549 else // True if all are equal
4550 InVal = BinaryOperator::createAnd(InVal, Comp);
4558 // No comparison is needed here, all indexes = 0
4559 ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
4560 Cond == ICmpInst::ICMP_EQ));
4563 // Only lower this if the icmp is the only user of the GEP or if we expect
4564 // the result to fold to a constant!
4565 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
4566 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
4567 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
4568 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
4569 Constant::getNullValue(Offset->getType()));
4571 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
4572 // If the base pointers are different, but the indices are the same, just
4573 // compare the base pointer.
4574 if (PtrBase != GEPRHS->getOperand(0)) {
4575 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
4576 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
4577 GEPRHS->getOperand(0)->getType();
4579 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
4580 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
4581 IndicesTheSame = false;
4585 // If all indices are the same, just compare the base pointers.
4587 return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
4588 GEPLHS->getOperand(0), GEPRHS->getOperand(0));
4590 // Otherwise, the base pointers are different and the indices are
4591 // different, bail out.
4595 // If one of the GEPs has all zero indices, recurse.
4596 bool AllZeros = true;
4597 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
4598 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
4599 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
4604 return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
4605 ICmpInst::getSwappedPredicate(Cond), I);
4607 // If the other GEP has all zero indices, recurse.
4609 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
4610 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
4611 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
4616 return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
4618 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
4619 // If the GEPs only differ by one index, compare it.
4620 unsigned NumDifferences = 0; // Keep track of # differences.
4621 unsigned DiffOperand = 0; // The operand that differs.
4622 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
4623 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
4624 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
4625 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
4626 // Irreconcilable differences.
4630 if (NumDifferences++) break;
4635 if (NumDifferences == 0) // SAME GEP?
4636 return ReplaceInstUsesWith(I, // No comparison is needed here.
4637 ConstantInt::get(Type::Int1Ty,
4638 isTrueWhenEqual(Cond)));
4640 else if (NumDifferences == 1) {
4641 Value *LHSV = GEPLHS->getOperand(DiffOperand);
4642 Value *RHSV = GEPRHS->getOperand(DiffOperand);
4643 // Make sure we do a signed comparison here.
4644 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
4648 // Only lower this if the icmp is the only user of the GEP or if we expect
4649 // the result to fold to a constant!
4650 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
4651 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
4652 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
4653 Value *L = EmitGEPOffset(GEPLHS, I, *this);
4654 Value *R = EmitGEPOffset(GEPRHS, I, *this);
4655 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
4661 Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
4662 bool Changed = SimplifyCompare(I);
4663 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4665 // Fold trivial predicates.
4666 if (I.getPredicate() == FCmpInst::FCMP_FALSE)
4667 return ReplaceInstUsesWith(I, Constant::getNullValue(Type::Int1Ty));
4668 if (I.getPredicate() == FCmpInst::FCMP_TRUE)
4669 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
4671 // Simplify 'fcmp pred X, X'
4673 switch (I.getPredicate()) {
4674 default: assert(0 && "Unknown predicate!");
4675 case FCmpInst::FCMP_UEQ: // True if unordered or equal
4676 case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal
4677 case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal
4678 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
4679 case FCmpInst::FCMP_OGT: // True if ordered and greater than
4680 case FCmpInst::FCMP_OLT: // True if ordered and less than
4681 case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal
4682 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 0));
4684 case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
4685 case FCmpInst::FCMP_ULT: // True if unordered or less than
4686 case FCmpInst::FCMP_UGT: // True if unordered or greater than
4687 case FCmpInst::FCMP_UNE: // True if unordered or not equal
4688 // Canonicalize these to be 'fcmp uno %X, 0.0'.
4689 I.setPredicate(FCmpInst::FCMP_UNO);
4690 I.setOperand(1, Constant::getNullValue(Op0->getType()));
4693 case FCmpInst::FCMP_ORD: // True if ordered (no nans)
4694 case FCmpInst::FCMP_OEQ: // True if ordered and equal
4695 case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
4696 case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
4697 // Canonicalize these to be 'fcmp ord %X, 0.0'.
4698 I.setPredicate(FCmpInst::FCMP_ORD);
4699 I.setOperand(1, Constant::getNullValue(Op0->getType()));
4704 if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef
4705 return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
4707 // Handle fcmp with constant RHS
4708 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
4709 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
4710 switch (LHSI->getOpcode()) {
4711 case Instruction::PHI:
4712 if (Instruction *NV = FoldOpIntoPhi(I))
4715 case Instruction::Select:
4716 // If either operand of the select is a constant, we can fold the
4717 // comparison into the select arms, which will cause one to be
4718 // constant folded and the select turned into a bitwise or.
4719 Value *Op1 = 0, *Op2 = 0;
4720 if (LHSI->hasOneUse()) {
4721 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
4722 // Fold the known value into the constant operand.
4723 Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
4724 // Insert a new FCmp of the other select operand.
4725 Op2 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
4726 LHSI->getOperand(2), RHSC,
4728 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
4729 // Fold the known value into the constant operand.
4730 Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
4731 // Insert a new FCmp of the other select operand.
4732 Op1 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
4733 LHSI->getOperand(1), RHSC,
4739 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
4744 return Changed ? &I : 0;
4747 Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
4748 bool Changed = SimplifyCompare(I);
4749 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4750 const Type *Ty = Op0->getType();
4754 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
4755 isTrueWhenEqual(I)));
4757 if (isa<UndefValue>(Op1)) // X icmp undef -> undef
4758 return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
4760 // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
4761 // addresses never equal each other! We already know that Op0 != Op1.
4762 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
4763 isa<ConstantPointerNull>(Op0)) &&
4764 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
4765 isa<ConstantPointerNull>(Op1)))
4766 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
4767 !isTrueWhenEqual(I)));
4769 // icmp's with boolean values can always be turned into bitwise operations
4770 if (Ty == Type::Int1Ty) {
4771 switch (I.getPredicate()) {
4772 default: assert(0 && "Invalid icmp instruction!");
4773 case ICmpInst::ICMP_EQ: { // icmp eq bool %A, %B -> ~(A^B)
4774 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
4775 InsertNewInstBefore(Xor, I);
4776 return BinaryOperator::createNot(Xor);
4778 case ICmpInst::ICMP_NE: // icmp eq bool %A, %B -> A^B
4779 return BinaryOperator::createXor(Op0, Op1);
4781 case ICmpInst::ICMP_UGT:
4782 case ICmpInst::ICMP_SGT:
4783 std::swap(Op0, Op1); // Change icmp gt -> icmp lt
4785 case ICmpInst::ICMP_ULT:
4786 case ICmpInst::ICMP_SLT: { // icmp lt bool A, B -> ~X & Y
4787 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
4788 InsertNewInstBefore(Not, I);
4789 return BinaryOperator::createAnd(Not, Op1);
4791 case ICmpInst::ICMP_UGE:
4792 case ICmpInst::ICMP_SGE:
4793 std::swap(Op0, Op1); // Change icmp ge -> icmp le
4795 case ICmpInst::ICMP_ULE:
4796 case ICmpInst::ICMP_SLE: { // icmp le bool %A, %B -> ~A | B
4797 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
4798 InsertNewInstBefore(Not, I);
4799 return BinaryOperator::createOr(Not, Op1);
4804 // See if we are doing a comparison between a constant and an instruction that
4805 // can be folded into the comparison.
4806 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
4807 switch (I.getPredicate()) {
4809 case ICmpInst::ICMP_ULT: // A <u MIN -> FALSE
4810 if (CI->isMinValue(false))
4811 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4812 if (CI->isMaxValue(false)) // A <u MAX -> A != MAX
4813 return new ICmpInst(ICmpInst::ICMP_NE, Op0,Op1);
4814 if (isMinValuePlusOne(CI,false)) // A <u MIN+1 -> A == MIN
4815 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
4816 // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
4817 if (CI->isMinValue(true))
4818 return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
4819 ConstantInt::getAllOnesValue(Op0->getType()));
4823 case ICmpInst::ICMP_SLT:
4824 if (CI->isMinValue(true)) // A <s MIN -> FALSE
4825 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4826 if (CI->isMaxValue(true)) // A <s MAX -> A != MAX
4827 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4828 if (isMinValuePlusOne(CI,true)) // A <s MIN+1 -> A == MIN
4829 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
4832 case ICmpInst::ICMP_UGT:
4833 if (CI->isMaxValue(false)) // A >u MAX -> FALSE
4834 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4835 if (CI->isMinValue(false)) // A >u MIN -> A != MIN
4836 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4837 if (isMaxValueMinusOne(CI, false)) // A >u MAX-1 -> A == MAX
4838 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
4840 // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
4841 if (CI->isMaxValue(true))
4842 return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
4843 ConstantInt::getNullValue(Op0->getType()));
4846 case ICmpInst::ICMP_SGT:
4847 if (CI->isMaxValue(true)) // A >s MAX -> FALSE
4848 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4849 if (CI->isMinValue(true)) // A >s MIN -> A != MIN
4850 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4851 if (isMaxValueMinusOne(CI, true)) // A >s MAX-1 -> A == MAX
4852 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
4855 case ICmpInst::ICMP_ULE:
4856 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
4857 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4858 if (CI->isMinValue(false)) // A <=u MIN -> A == MIN
4859 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
4860 if (isMaxValueMinusOne(CI,false)) // A <=u MAX-1 -> A != MAX
4861 return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
4864 case ICmpInst::ICMP_SLE:
4865 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
4866 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4867 if (CI->isMinValue(true)) // A <=s MIN -> A == MIN
4868 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
4869 if (isMaxValueMinusOne(CI,true)) // A <=s MAX-1 -> A != MAX
4870 return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
4873 case ICmpInst::ICMP_UGE:
4874 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
4875 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4876 if (CI->isMaxValue(false)) // A >=u MAX -> A == MAX
4877 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
4878 if (isMinValuePlusOne(CI,false)) // A >=u MIN-1 -> A != MIN
4879 return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
4882 case ICmpInst::ICMP_SGE:
4883 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
4884 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4885 if (CI->isMaxValue(true)) // A >=s MAX -> A == MAX
4886 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
4887 if (isMinValuePlusOne(CI,true)) // A >=s MIN-1 -> A != MIN
4888 return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
4892 // If we still have a icmp le or icmp ge instruction, turn it into the
4893 // appropriate icmp lt or icmp gt instruction. Since the border cases have
4894 // already been handled above, this requires little checking.
4896 switch (I.getPredicate()) {
4898 case ICmpInst::ICMP_ULE:
4899 return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
4900 case ICmpInst::ICMP_SLE:
4901 return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
4902 case ICmpInst::ICMP_UGE:
4903 return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
4904 case ICmpInst::ICMP_SGE:
4905 return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
4908 // See if we can fold the comparison based on bits known to be zero or one
4909 // in the input. If this comparison is a normal comparison, it demands all
4910 // bits, if it is a sign bit comparison, it only demands the sign bit.
4913 bool isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
4915 uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
4916 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
4917 if (SimplifyDemandedBits(Op0,
4918 isSignBit ? APInt::getSignBit(BitWidth)
4919 : APInt::getAllOnesValue(BitWidth),
4920 KnownZero, KnownOne, 0))
4923 // Given the known and unknown bits, compute a range that the LHS could be
4925 if ((KnownOne | KnownZero) != 0) {
4926 // Compute the Min, Max and RHS values based on the known bits. For the
4927 // EQ and NE we use unsigned values.
4928 APInt Min(BitWidth, 0), Max(BitWidth, 0);
4929 const APInt& RHSVal = CI->getValue();
4930 if (ICmpInst::isSignedPredicate(I.getPredicate())) {
4931 ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min,
4934 ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min,
4937 switch (I.getPredicate()) { // LE/GE have been folded already.
4938 default: assert(0 && "Unknown icmp opcode!");
4939 case ICmpInst::ICMP_EQ:
4940 if (Max.ult(RHSVal) || Min.ugt(RHSVal))
4941 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4943 case ICmpInst::ICMP_NE:
4944 if (Max.ult(RHSVal) || Min.ugt(RHSVal))
4945 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4947 case ICmpInst::ICMP_ULT:
4948 if (Max.ult(RHSVal))
4949 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4950 if (Min.uge(RHSVal))
4951 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4953 case ICmpInst::ICMP_UGT:
4954 if (Min.ugt(RHSVal))
4955 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4956 if (Max.ule(RHSVal))
4957 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4959 case ICmpInst::ICMP_SLT:
4960 if (Max.slt(RHSVal))
4961 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4962 if (Min.sgt(RHSVal))
4963 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4965 case ICmpInst::ICMP_SGT:
4966 if (Min.sgt(RHSVal))
4967 return ReplaceInstUsesWith(I, ConstantInt::getTrue());
4968 if (Max.sle(RHSVal))
4969 return ReplaceInstUsesWith(I, ConstantInt::getFalse());
4974 // Since the RHS is a ConstantInt (CI), if the left hand side is an
4975 // instruction, see if that instruction also has constants so that the
4976 // instruction can be folded into the icmp
4977 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
4978 if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
4982 // Handle icmp with constant (but not simple integer constant) RHS
4983 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
4984 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
4985 switch (LHSI->getOpcode()) {
4986 case Instruction::GetElementPtr:
4987 if (RHSC->isNullValue()) {
4988 // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
4989 bool isAllZeros = true;
4990 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
4991 if (!isa<Constant>(LHSI->getOperand(i)) ||
4992 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
4997 return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
4998 Constant::getNullValue(LHSI->getOperand(0)->getType()));
5002 case Instruction::PHI:
5003 if (Instruction *NV = FoldOpIntoPhi(I))
5006 case Instruction::Select: {
5007 // If either operand of the select is a constant, we can fold the
5008 // comparison into the select arms, which will cause one to be
5009 // constant folded and the select turned into a bitwise or.
5010 Value *Op1 = 0, *Op2 = 0;
5011 if (LHSI->hasOneUse()) {
5012 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
5013 // Fold the known value into the constant operand.
5014 Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
5015 // Insert a new ICmp of the other select operand.
5016 Op2 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
5017 LHSI->getOperand(2), RHSC,
5019 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
5020 // Fold the known value into the constant operand.
5021 Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
5022 // Insert a new ICmp of the other select operand.
5023 Op1 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
5024 LHSI->getOperand(1), RHSC,
5030 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
5033 case Instruction::Malloc:
5034 // If we have (malloc != null), and if the malloc has a single use, we
5035 // can assume it is successful and remove the malloc.
5036 if (LHSI->hasOneUse() && isa<ConstantPointerNull>(RHSC)) {
5037 AddToWorkList(LHSI);
5038 return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
5039 !isTrueWhenEqual(I)));
5045 // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
5046 if (User *GEP = dyn_castGetElementPtr(Op0))
5047 if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
5049 if (User *GEP = dyn_castGetElementPtr(Op1))
5050 if (Instruction *NI = FoldGEPICmp(GEP, Op0,
5051 ICmpInst::getSwappedPredicate(I.getPredicate()), I))
5054 // Test to see if the operands of the icmp are casted versions of other
5055 // values. If the ptr->ptr cast can be stripped off both arguments, we do so
5057 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
5058 if (isa<PointerType>(Op0->getType()) &&
5059 (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
5060 // We keep moving the cast from the left operand over to the right
5061 // operand, where it can often be eliminated completely.
5062 Op0 = CI->getOperand(0);
5064 // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
5065 // so eliminate it as well.
5066 if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
5067 Op1 = CI2->getOperand(0);
5069 // If Op1 is a constant, we can fold the cast into the constant.
5070 if (Op0->getType() != Op1->getType())
5071 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
5072 Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
5074 // Otherwise, cast the RHS right before the icmp
5075 Op1 = InsertCastBefore(Instruction::BitCast, Op1, Op0->getType(), I);
5077 return new ICmpInst(I.getPredicate(), Op0, Op1);
5081 if (isa<CastInst>(Op0)) {
5082 // Handle the special case of: icmp (cast bool to X), <cst>
5083 // This comes up when you have code like
5086 // For generality, we handle any zero-extension of any operand comparison
5087 // with a constant or another cast from the same type.
5088 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
5089 if (Instruction *R = visitICmpInstWithCastAndCast(I))
5093 if (I.isEquality()) {
5094 Value *A, *B, *C, *D;
5095 if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
5096 if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
5097 Value *OtherVal = A == Op1 ? B : A;
5098 return new ICmpInst(I.getPredicate(), OtherVal,
5099 Constant::getNullValue(A->getType()));
5102 if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
5103 // A^c1 == C^c2 --> A == C^(c1^c2)
5104 if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
5105 if (ConstantInt *C2 = dyn_cast<ConstantInt>(D))
5106 if (Op1->hasOneUse()) {
5107 Constant *NC = ConstantInt::get(C1->getValue() ^ C2->getValue());
5108 Instruction *Xor = BinaryOperator::createXor(C, NC, "tmp");
5109 return new ICmpInst(I.getPredicate(), A,
5110 InsertNewInstBefore(Xor, I));
5113 // A^B == A^D -> B == D
5114 if (A == C) return new ICmpInst(I.getPredicate(), B, D);
5115 if (A == D) return new ICmpInst(I.getPredicate(), B, C);
5116 if (B == C) return new ICmpInst(I.getPredicate(), A, D);
5117 if (B == D) return new ICmpInst(I.getPredicate(), A, C);
5121 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
5122 (A == Op0 || B == Op0)) {
5123 // A == (A^B) -> B == 0
5124 Value *OtherVal = A == Op0 ? B : A;
5125 return new ICmpInst(I.getPredicate(), OtherVal,
5126 Constant::getNullValue(A->getType()));
5128 if (match(Op0, m_Sub(m_Value(A), m_Value(B))) && A == Op1) {
5129 // (A-B) == A -> B == 0
5130 return new ICmpInst(I.getPredicate(), B,
5131 Constant::getNullValue(B->getType()));
5133 if (match(Op1, m_Sub(m_Value(A), m_Value(B))) && A == Op0) {
5134 // A == (A-B) -> B == 0
5135 return new ICmpInst(I.getPredicate(), B,
5136 Constant::getNullValue(B->getType()));
5139 // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
5140 if (Op0->hasOneUse() && Op1->hasOneUse() &&
5141 match(Op0, m_And(m_Value(A), m_Value(B))) &&
5142 match(Op1, m_And(m_Value(C), m_Value(D)))) {
5143 Value *X = 0, *Y = 0, *Z = 0;
5146 X = B; Y = D; Z = A;
5147 } else if (A == D) {
5148 X = B; Y = C; Z = A;
5149 } else if (B == C) {
5150 X = A; Y = D; Z = B;
5151 } else if (B == D) {
5152 X = A; Y = C; Z = B;
5155 if (X) { // Build (X^Y) & Z
5156 Op1 = InsertNewInstBefore(BinaryOperator::createXor(X, Y, "tmp"), I);
5157 Op1 = InsertNewInstBefore(BinaryOperator::createAnd(Op1, Z, "tmp"), I);
5158 I.setOperand(0, Op1);
5159 I.setOperand(1, Constant::getNullValue(Op1->getType()));
5164 return Changed ? &I : 0;
5168 /// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
5169 /// and CmpRHS are both known to be integer constants.
5170 Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
5171 ConstantInt *DivRHS) {
5172 ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
5173 const APInt &CmpRHSV = CmpRHS->getValue();
5175 // FIXME: If the operand types don't match the type of the divide
5176 // then don't attempt this transform. The code below doesn't have the
5177 // logic to deal with a signed divide and an unsigned compare (and
5178 // vice versa). This is because (x /s C1) <s C2 produces different
5179 // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
5180 // (x /u C1) <u C2. Simply casting the operands and result won't
5181 // work. :( The if statement below tests that condition and bails
5183 bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
5184 if (!ICI.isEquality() && DivIsSigned != ICI.isSignedPredicate())
5186 if (DivRHS->isZero())
5187 return 0; // The ProdOV computation fails on divide by zero.
5189 // Compute Prod = CI * DivRHS. We are essentially solving an equation
5190 // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
5191 // C2 (CI). By solving for X we can turn this into a range check
5192 // instead of computing a divide.
5193 ConstantInt *Prod = Multiply(CmpRHS, DivRHS);
5195 // Determine if the product overflows by seeing if the product is
5196 // not equal to the divide. Make sure we do the same kind of divide
5197 // as in the LHS instruction that we're folding.
5198 bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
5199 ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
5201 // Get the ICmp opcode
5202 ICmpInst::Predicate Pred = ICI.getPredicate();
5204 // Figure out the interval that is being checked. For example, a comparison
5205 // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
5206 // Compute this interval based on the constants involved and the signedness of
5207 // the compare/divide. This computes a half-open interval, keeping track of
5208 // whether either value in the interval overflows. After analysis each
5209 // overflow variable is set to 0 if it's corresponding bound variable is valid
5210 // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
5211 int LoOverflow = 0, HiOverflow = 0;
5212 ConstantInt *LoBound = 0, *HiBound = 0;
5215 if (!DivIsSigned) { // udiv
5216 // e.g. X/5 op 3 --> [15, 20)
5218 HiOverflow = LoOverflow = ProdOV;
5220 HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false);
5221 } else if (DivRHS->getValue().isPositive()) { // Divisor is > 0.
5222 if (CmpRHSV == 0) { // (X / pos) op 0
5223 // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
5224 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
5226 } else if (CmpRHSV.isPositive()) { // (X / pos) op pos
5227 LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
5228 HiOverflow = LoOverflow = ProdOV;
5230 HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true);
5231 } else { // (X / pos) op neg
5232 // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
5233 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
5234 LoOverflow = AddWithOverflow(LoBound, Prod,
5235 cast<ConstantInt>(DivRHSH), true) ? -1 : 0;
5236 HiBound = AddOne(Prod);
5237 HiOverflow = ProdOV ? -1 : 0;
5239 } else { // Divisor is < 0.
5240 if (CmpRHSV == 0) { // (X / neg) op 0
5241 // e.g. X/-5 op 0 --> [-4, 5)
5242 LoBound = AddOne(DivRHS);
5243 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
5244 if (HiBound == DivRHS) { // -INTMIN = INTMIN
5245 HiOverflow = 1; // [INTMIN+1, overflow)
5246 HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
5248 } else if (CmpRHSV.isPositive()) { // (X / neg) op pos
5249 // e.g. X/-5 op 3 --> [-19, -14)
5250 HiOverflow = LoOverflow = ProdOV ? -1 : 0;
5252 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS), true) ?-1:0;
5253 HiBound = AddOne(Prod);
5254 } else { // (X / neg) op neg
5255 // e.g. X/-5 op -3 --> [15, 20)
5257 LoOverflow = HiOverflow = ProdOV ? 1 : 0;
5258 HiBound = Subtract(Prod, DivRHS);
5261 // Dividing by a negative swaps the condition. LT <-> GT
5262 Pred = ICmpInst::getSwappedPredicate(Pred);
5265 Value *X = DivI->getOperand(0);
5267 default: assert(0 && "Unhandled icmp opcode!");
5268 case ICmpInst::ICMP_EQ:
5269 if (LoOverflow && HiOverflow)
5270 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5271 else if (HiOverflow)
5272 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
5273 ICmpInst::ICMP_UGE, X, LoBound);
5274 else if (LoOverflow)
5275 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
5276 ICmpInst::ICMP_ULT, X, HiBound);
5278 return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
5279 case ICmpInst::ICMP_NE:
5280 if (LoOverflow && HiOverflow)
5281 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5282 else if (HiOverflow)
5283 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
5284 ICmpInst::ICMP_ULT, X, LoBound);
5285 else if (LoOverflow)
5286 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
5287 ICmpInst::ICMP_UGE, X, HiBound);
5289 return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
5290 case ICmpInst::ICMP_ULT:
5291 case ICmpInst::ICMP_SLT:
5292 if (LoOverflow == +1) // Low bound is greater than input range.
5293 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5294 if (LoOverflow == -1) // Low bound is less than input range.
5295 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5296 return new ICmpInst(Pred, X, LoBound);
5297 case ICmpInst::ICMP_UGT:
5298 case ICmpInst::ICMP_SGT:
5299 if (HiOverflow == +1) // High bound greater than input range.
5300 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5301 else if (HiOverflow == -1) // High bound less than input range.
5302 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5303 if (Pred == ICmpInst::ICMP_UGT)
5304 return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
5306 return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
5311 /// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
5313 Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
5316 const APInt &RHSV = RHS->getValue();
5318 switch (LHSI->getOpcode()) {
5319 case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
5320 if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
5321 // If this is a comparison that tests the signbit (X < 0) or (x > -1),
5323 if (ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0 ||
5324 ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue()) {
5325 Value *CompareVal = LHSI->getOperand(0);
5327 // If the sign bit of the XorCST is not set, there is no change to
5328 // the operation, just stop using the Xor.
5329 if (!XorCST->getValue().isNegative()) {
5330 ICI.setOperand(0, CompareVal);
5331 AddToWorkList(LHSI);
5335 // Was the old condition true if the operand is positive?
5336 bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
5338 // If so, the new one isn't.
5339 isTrueIfPositive ^= true;
5341 if (isTrueIfPositive)
5342 return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, SubOne(RHS));
5344 return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, AddOne(RHS));
5348 case Instruction::And: // (icmp pred (and X, AndCST), RHS)
5349 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
5350 LHSI->getOperand(0)->hasOneUse()) {
5351 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
5353 // If the LHS is an AND of a truncating cast, we can widen the
5354 // and/compare to be the input width without changing the value
5355 // produced, eliminating a cast.
5356 if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
5357 // We can do this transformation if either the AND constant does not
5358 // have its sign bit set or if it is an equality comparison.
5359 // Extending a relational comparison when we're checking the sign
5360 // bit would not work.
5361 if (Cast->hasOneUse() &&
5362 (ICI.isEquality() || AndCST->getValue().isPositive() &&
5363 RHSV.isPositive())) {
5365 cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
5366 APInt NewCST = AndCST->getValue();
5367 NewCST.zext(BitWidth);
5369 NewCI.zext(BitWidth);
5370 Instruction *NewAnd =
5371 BinaryOperator::createAnd(Cast->getOperand(0),
5372 ConstantInt::get(NewCST),LHSI->getName());
5373 InsertNewInstBefore(NewAnd, ICI);
5374 return new ICmpInst(ICI.getPredicate(), NewAnd,
5375 ConstantInt::get(NewCI));
5379 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
5380 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
5381 // happens a LOT in code produced by the C front-end, for bitfield
5383 BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
5384 if (Shift && !Shift->isShift())
5388 ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
5389 const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
5390 const Type *AndTy = AndCST->getType(); // Type of the and.
5392 // We can fold this as long as we can't shift unknown bits
5393 // into the mask. This can only happen with signed shift
5394 // rights, as they sign-extend.
5396 bool CanFold = Shift->isLogicalShift();
5398 // To test for the bad case of the signed shr, see if any
5399 // of the bits shifted in could be tested after the mask.
5400 uint32_t TyBits = Ty->getPrimitiveSizeInBits();
5401 int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
5403 uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
5404 if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
5405 AndCST->getValue()) == 0)
5411 if (Shift->getOpcode() == Instruction::Shl)
5412 NewCst = ConstantExpr::getLShr(RHS, ShAmt);
5414 NewCst = ConstantExpr::getShl(RHS, ShAmt);
5416 // Check to see if we are shifting out any of the bits being
5418 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != RHS) {
5419 // If we shifted bits out, the fold is not going to work out.
5420 // As a special case, check to see if this means that the
5421 // result is always true or false now.
5422 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
5423 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5424 if (ICI.getPredicate() == ICmpInst::ICMP_NE)
5425 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5427 ICI.setOperand(1, NewCst);
5428 Constant *NewAndCST;
5429 if (Shift->getOpcode() == Instruction::Shl)
5430 NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
5432 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
5433 LHSI->setOperand(1, NewAndCST);
5434 LHSI->setOperand(0, Shift->getOperand(0));
5435 AddToWorkList(Shift); // Shift is dead.
5436 AddUsesToWorkList(ICI);
5442 // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
5443 // preferable because it allows the C<<Y expression to be hoisted out
5444 // of a loop if Y is invariant and X is not.
5445 if (Shift && Shift->hasOneUse() && RHSV == 0 &&
5446 ICI.isEquality() && !Shift->isArithmeticShift() &&
5447 isa<Instruction>(Shift->getOperand(0))) {
5450 if (Shift->getOpcode() == Instruction::LShr) {
5451 NS = BinaryOperator::createShl(AndCST,
5452 Shift->getOperand(1), "tmp");
5454 // Insert a logical shift.
5455 NS = BinaryOperator::createLShr(AndCST,
5456 Shift->getOperand(1), "tmp");
5458 InsertNewInstBefore(cast<Instruction>(NS), ICI);
5460 // Compute X & (C << Y).
5461 Instruction *NewAnd =
5462 BinaryOperator::createAnd(Shift->getOperand(0), NS, LHSI->getName());
5463 InsertNewInstBefore(NewAnd, ICI);
5465 ICI.setOperand(0, NewAnd);
5471 case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
5472 ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
5475 uint32_t TypeBits = RHSV.getBitWidth();
5477 // Check that the shift amount is in range. If not, don't perform
5478 // undefined shifts. When the shift is visited it will be
5480 if (ShAmt->uge(TypeBits))
5483 if (ICI.isEquality()) {
5484 // If we are comparing against bits always shifted out, the
5485 // comparison cannot succeed.
5487 ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), ShAmt);
5488 if (Comp != RHS) {// Comparing against a bit that we know is zero.
5489 bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
5490 Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
5491 return ReplaceInstUsesWith(ICI, Cst);
5494 if (LHSI->hasOneUse()) {
5495 // Otherwise strength reduce the shift into an and.
5496 uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
5498 ConstantInt::get(APInt::getLowBitsSet(TypeBits, TypeBits-ShAmtVal));
5501 BinaryOperator::createAnd(LHSI->getOperand(0),
5502 Mask, LHSI->getName()+".mask");
5503 Value *And = InsertNewInstBefore(AndI, ICI);
5504 return new ICmpInst(ICI.getPredicate(), And,
5505 ConstantInt::get(RHSV.lshr(ShAmtVal)));
5509 // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
5510 bool TrueIfSigned = false;
5511 if (LHSI->hasOneUse() &&
5512 isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
5513 // (X << 31) <s 0 --> (X&1) != 0
5514 Constant *Mask = ConstantInt::get(APInt(TypeBits, 1) <<
5515 (TypeBits-ShAmt->getZExtValue()-1));
5517 BinaryOperator::createAnd(LHSI->getOperand(0),
5518 Mask, LHSI->getName()+".mask");
5519 Value *And = InsertNewInstBefore(AndI, ICI);
5521 return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
5522 And, Constant::getNullValue(And->getType()));
5527 case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
5528 case Instruction::AShr: {
5529 ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
5532 if (ICI.isEquality()) {
5533 // Check that the shift amount is in range. If not, don't perform
5534 // undefined shifts. When the shift is visited it will be
5536 uint32_t TypeBits = RHSV.getBitWidth();
5537 if (ShAmt->uge(TypeBits))
5539 uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
5541 // If we are comparing against bits always shifted out, the
5542 // comparison cannot succeed.
5543 APInt Comp = RHSV << ShAmtVal;
5544 if (LHSI->getOpcode() == Instruction::LShr)
5545 Comp = Comp.lshr(ShAmtVal);
5547 Comp = Comp.ashr(ShAmtVal);
5549 if (Comp != RHSV) { // Comparing against a bit that we know is zero.
5550 bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
5551 Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
5552 return ReplaceInstUsesWith(ICI, Cst);
5555 if (LHSI->hasOneUse() || RHSV == 0) {
5556 // Otherwise strength reduce the shift into an and.
5557 APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
5558 Constant *Mask = ConstantInt::get(Val);
5561 BinaryOperator::createAnd(LHSI->getOperand(0),
5562 Mask, LHSI->getName()+".mask");
5563 Value *And = InsertNewInstBefore(AndI, ICI);
5564 return new ICmpInst(ICI.getPredicate(), And,
5565 ConstantExpr::getShl(RHS, ShAmt));
5571 case Instruction::SDiv:
5572 case Instruction::UDiv:
5573 // Fold: icmp pred ([us]div X, C1), C2 -> range test
5574 // Fold this div into the comparison, producing a range check.
5575 // Determine, based on the divide type, what the range is being
5576 // checked. If there is an overflow on the low or high side, remember
5577 // it, otherwise compute the range [low, hi) bounding the new value.
5578 // See: InsertRangeTest above for the kinds of replacements possible.
5579 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
5580 if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
5586 // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
5587 if (ICI.isEquality()) {
5588 bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
5590 // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
5591 // the second operand is a constant, simplify a bit.
5592 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
5593 switch (BO->getOpcode()) {
5594 case Instruction::SRem:
5595 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
5596 if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
5597 const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
5598 if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
5599 Instruction *NewRem =
5600 BinaryOperator::createURem(BO->getOperand(0), BO->getOperand(1),
5602 InsertNewInstBefore(NewRem, ICI);
5603 return new ICmpInst(ICI.getPredicate(), NewRem,
5604 Constant::getNullValue(BO->getType()));
5608 case Instruction::Add:
5609 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
5610 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
5611 if (BO->hasOneUse())
5612 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
5613 Subtract(RHS, BOp1C));
5614 } else if (RHSV == 0) {
5615 // Replace ((add A, B) != 0) with (A != -B) if A or B is
5616 // efficiently invertible, or if the add has just this one use.
5617 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
5619 if (Value *NegVal = dyn_castNegVal(BOp1))
5620 return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
5621 else if (Value *NegVal = dyn_castNegVal(BOp0))
5622 return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
5623 else if (BO->hasOneUse()) {
5624 Instruction *Neg = BinaryOperator::createNeg(BOp1);
5625 InsertNewInstBefore(Neg, ICI);
5627 return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
5631 case Instruction::Xor:
5632 // For the xor case, we can xor two constants together, eliminating
5633 // the explicit xor.
5634 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
5635 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
5636 ConstantExpr::getXor(RHS, BOC));
5639 case Instruction::Sub:
5640 // Replace (([sub|xor] A, B) != 0) with (A != B)
5642 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
5646 case Instruction::Or:
5647 // If bits are being or'd in that are not present in the constant we
5648 // are comparing against, then the comparison could never succeed!
5649 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
5650 Constant *NotCI = ConstantExpr::getNot(RHS);
5651 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
5652 return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
5657 case Instruction::And:
5658 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
5659 // If bits are being compared against that are and'd out, then the
5660 // comparison can never succeed!
5661 if ((RHSV & ~BOC->getValue()) != 0)
5662 return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
5665 // If we have ((X & C) == C), turn it into ((X & C) != 0).
5666 if (RHS == BOC && RHSV.isPowerOf2())
5667 return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
5668 ICmpInst::ICMP_NE, LHSI,
5669 Constant::getNullValue(RHS->getType()));
5671 // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
5672 if (isSignBit(BOC)) {
5673 Value *X = BO->getOperand(0);
5674 Constant *Zero = Constant::getNullValue(X->getType());
5675 ICmpInst::Predicate pred = isICMP_NE ?
5676 ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
5677 return new ICmpInst(pred, X, Zero);
5680 // ((X & ~7) == 0) --> X < 8
5681 if (RHSV == 0 && isHighOnes(BOC)) {
5682 Value *X = BO->getOperand(0);
5683 Constant *NegX = ConstantExpr::getNeg(BOC);
5684 ICmpInst::Predicate pred = isICMP_NE ?
5685 ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
5686 return new ICmpInst(pred, X, NegX);
5691 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
5692 // Handle icmp {eq|ne} <intrinsic>, intcst.
5693 if (II->getIntrinsicID() == Intrinsic::bswap) {
5695 ICI.setOperand(0, II->getOperand(1));
5696 ICI.setOperand(1, ConstantInt::get(RHSV.byteSwap()));
5700 } else { // Not a ICMP_EQ/ICMP_NE
5701 // If the LHS is a cast from an integral value of the same size,
5702 // then since we know the RHS is a constant, try to simlify.
5703 if (CastInst *Cast = dyn_cast<CastInst>(LHSI)) {
5704 Value *CastOp = Cast->getOperand(0);
5705 const Type *SrcTy = CastOp->getType();
5706 uint32_t SrcTySize = SrcTy->getPrimitiveSizeInBits();
5707 if (SrcTy->isInteger() &&
5708 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
5709 // If this is an unsigned comparison, try to make the comparison use
5710 // smaller constant values.
5711 if (ICI.getPredicate() == ICmpInst::ICMP_ULT && RHSV.isSignBit()) {
5712 // X u< 128 => X s> -1
5713 return new ICmpInst(ICmpInst::ICMP_SGT, CastOp,
5714 ConstantInt::get(APInt::getAllOnesValue(SrcTySize)));
5715 } else if (ICI.getPredicate() == ICmpInst::ICMP_UGT &&
5716 RHSV == APInt::getSignedMaxValue(SrcTySize)) {
5717 // X u> 127 => X s< 0
5718 return new ICmpInst(ICmpInst::ICMP_SLT, CastOp,
5719 Constant::getNullValue(SrcTy));
5727 /// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
5728 /// We only handle extending casts so far.
5730 Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
5731 const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
5732 Value *LHSCIOp = LHSCI->getOperand(0);
5733 const Type *SrcTy = LHSCIOp->getType();
5734 const Type *DestTy = LHSCI->getType();
5737 // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
5738 // integer type is the same size as the pointer type.
5739 if (LHSCI->getOpcode() == Instruction::PtrToInt &&
5740 getTargetData().getPointerSizeInBits() ==
5741 cast<IntegerType>(DestTy)->getBitWidth()) {
5743 if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
5744 RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
5745 } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
5746 RHSOp = RHSC->getOperand(0);
5747 // If the pointer types don't match, insert a bitcast.
5748 if (LHSCIOp->getType() != RHSOp->getType())
5749 RHSOp = InsertCastBefore(Instruction::BitCast, RHSOp,
5750 LHSCIOp->getType(), ICI);
5754 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
5757 // The code below only handles extension cast instructions, so far.
5759 if (LHSCI->getOpcode() != Instruction::ZExt &&
5760 LHSCI->getOpcode() != Instruction::SExt)
5763 bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
5764 bool isSignedCmp = ICI.isSignedPredicate();
5766 if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
5767 // Not an extension from the same type?
5768 RHSCIOp = CI->getOperand(0);
5769 if (RHSCIOp->getType() != LHSCIOp->getType())
5772 // If the signedness of the two compares doesn't agree (i.e. one is a sext
5773 // and the other is a zext), then we can't handle this.
5774 if (CI->getOpcode() != LHSCI->getOpcode())
5777 // Likewise, if the signedness of the [sz]exts and the compare don't match,
5778 // then we can't handle this.
5779 if (isSignedExt != isSignedCmp && !ICI.isEquality())
5782 // Okay, just insert a compare of the reduced operands now!
5783 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
5786 // If we aren't dealing with a constant on the RHS, exit early
5787 ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
5791 // Compute the constant that would happen if we truncated to SrcTy then
5792 // reextended to DestTy.
5793 Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
5794 Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
5796 // If the re-extended constant didn't change...
5798 // Make sure that sign of the Cmp and the sign of the Cast are the same.
5799 // For example, we might have:
5800 // %A = sext short %X to uint
5801 // %B = icmp ugt uint %A, 1330
5802 // It is incorrect to transform this into
5803 // %B = icmp ugt short %X, 1330
5804 // because %A may have negative value.
5806 // However, it is OK if SrcTy is bool (See cast-set.ll testcase)
5807 // OR operation is EQ/NE.
5808 if (isSignedExt == isSignedCmp || SrcTy == Type::Int1Ty || ICI.isEquality())
5809 return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
5814 // The re-extended constant changed so the constant cannot be represented
5815 // in the shorter type. Consequently, we cannot emit a simple comparison.
5817 // First, handle some easy cases. We know the result cannot be equal at this
5818 // point so handle the ICI.isEquality() cases
5819 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
5820 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
5821 if (ICI.getPredicate() == ICmpInst::ICMP_NE)
5822 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
5824 // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
5825 // should have been folded away previously and not enter in here.
5828 // We're performing a signed comparison.
5829 if (cast<ConstantInt>(CI)->getValue().isNegative())
5830 Result = ConstantInt::getFalse(); // X < (small) --> false
5832 Result = ConstantInt::getTrue(); // X < (large) --> true
5834 // We're performing an unsigned comparison.
5836 // We're performing an unsigned comp with a sign extended value.
5837 // This is true if the input is >= 0. [aka >s -1]
5838 Constant *NegOne = ConstantInt::getAllOnesValue(SrcTy);
5839 Result = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_SGT, LHSCIOp,
5840 NegOne, ICI.getName()), ICI);
5842 // Unsigned extend & unsigned compare -> always true.
5843 Result = ConstantInt::getTrue();
5847 // Finally, return the value computed.
5848 if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
5849 ICI.getPredicate() == ICmpInst::ICMP_SLT) {
5850 return ReplaceInstUsesWith(ICI, Result);
5852 assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
5853 ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
5854 "ICmp should be folded!");
5855 if (Constant *CI = dyn_cast<Constant>(Result))
5856 return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
5858 return BinaryOperator::createNot(Result);
5862 Instruction *InstCombiner::visitShl(BinaryOperator &I) {
5863 return commonShiftTransforms(I);
5866 Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
5867 return commonShiftTransforms(I);
5870 Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
5871 return commonShiftTransforms(I);
5874 Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
5875 assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
5876 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
5878 // shl X, 0 == X and shr X, 0 == X
5879 // shl 0, X == 0 and shr 0, X == 0
5880 if (Op1 == Constant::getNullValue(Op1->getType()) ||
5881 Op0 == Constant::getNullValue(Op0->getType()))
5882 return ReplaceInstUsesWith(I, Op0);
5884 if (isa<UndefValue>(Op0)) {
5885 if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
5886 return ReplaceInstUsesWith(I, Op0);
5887 else // undef << X -> 0, undef >>u X -> 0
5888 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
5890 if (isa<UndefValue>(Op1)) {
5891 if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
5892 return ReplaceInstUsesWith(I, Op0);
5893 else // X << undef, X >>u undef -> 0
5894 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
5897 // ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
5898 if (I.getOpcode() == Instruction::AShr)
5899 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
5900 if (CSI->isAllOnesValue())
5901 return ReplaceInstUsesWith(I, CSI);
5903 // Try to fold constant and into select arguments.
5904 if (isa<Constant>(Op0))
5905 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
5906 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
5909 // See if we can turn a signed shr into an unsigned shr.
5910 if (I.isArithmeticShift()) {
5911 if (MaskedValueIsZero(Op0,
5912 APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()))) {
5913 return BinaryOperator::createLShr(Op0, Op1, I.getName());
5917 if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
5918 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
5923 Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
5924 BinaryOperator &I) {
5925 bool isLeftShift = I.getOpcode() == Instruction::Shl;
5927 // See if we can simplify any instructions used by the instruction whose sole
5928 // purpose is to compute bits we don't care about.
5929 uint32_t TypeBits = Op0->getType()->getPrimitiveSizeInBits();
5930 APInt KnownZero(TypeBits, 0), KnownOne(TypeBits, 0);
5931 if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(TypeBits),
5932 KnownZero, KnownOne))
5935 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
5936 // of a signed value.
5938 if (Op1->uge(TypeBits)) {
5939 if (I.getOpcode() != Instruction::AShr)
5940 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
5942 I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
5947 // ((X*C1) << C2) == (X * (C1 << C2))
5948 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
5949 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
5950 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
5951 return BinaryOperator::createMul(BO->getOperand(0),
5952 ConstantExpr::getShl(BOOp, Op1));
5954 // Try to fold constant and into select arguments.
5955 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
5956 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
5958 if (isa<PHINode>(Op0))
5959 if (Instruction *NV = FoldOpIntoPhi(I))
5962 if (Op0->hasOneUse()) {
5963 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
5964 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
5967 switch (Op0BO->getOpcode()) {
5969 case Instruction::Add:
5970 case Instruction::And:
5971 case Instruction::Or:
5972 case Instruction::Xor: {
5973 // These operators commute.
5974 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
5975 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
5976 match(Op0BO->getOperand(1),
5977 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
5978 Instruction *YS = BinaryOperator::createShl(
5979 Op0BO->getOperand(0), Op1,
5981 InsertNewInstBefore(YS, I); // (Y << C)
5983 BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
5984 Op0BO->getOperand(1)->getName());
5985 InsertNewInstBefore(X, I); // (X + (Y << C))
5986 uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
5987 return BinaryOperator::createAnd(X, ConstantInt::get(
5988 APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
5991 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
5992 Value *Op0BOOp1 = Op0BO->getOperand(1);
5993 if (isLeftShift && Op0BOOp1->hasOneUse() &&
5995 m_And(m_Shr(m_Value(V1), m_Value(V2)),m_ConstantInt(CC))) &&
5996 cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse() &&
5998 Instruction *YS = BinaryOperator::createShl(
5999 Op0BO->getOperand(0), Op1,
6001 InsertNewInstBefore(YS, I); // (Y << C)
6003 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
6004 V1->getName()+".mask");
6005 InsertNewInstBefore(XM, I); // X & (CC << C)
6007 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
6012 case Instruction::Sub: {
6013 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
6014 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
6015 match(Op0BO->getOperand(0),
6016 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
6017 Instruction *YS = BinaryOperator::createShl(
6018 Op0BO->getOperand(1), Op1,
6020 InsertNewInstBefore(YS, I); // (Y << C)
6022 BinaryOperator::create(Op0BO->getOpcode(), V1, YS,
6023 Op0BO->getOperand(0)->getName());
6024 InsertNewInstBefore(X, I); // (X + (Y << C))
6025 uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
6026 return BinaryOperator::createAnd(X, ConstantInt::get(
6027 APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
6030 // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
6031 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
6032 match(Op0BO->getOperand(0),
6033 m_And(m_Shr(m_Value(V1), m_Value(V2)),
6034 m_ConstantInt(CC))) && V2 == Op1 &&
6035 cast<BinaryOperator>(Op0BO->getOperand(0))
6036 ->getOperand(0)->hasOneUse()) {
6037 Instruction *YS = BinaryOperator::createShl(
6038 Op0BO->getOperand(1), Op1,
6040 InsertNewInstBefore(YS, I); // (Y << C)
6042 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
6043 V1->getName()+".mask");
6044 InsertNewInstBefore(XM, I); // X & (CC << C)
6046 return BinaryOperator::create(Op0BO->getOpcode(), XM, YS);
6054 // If the operand is an bitwise operator with a constant RHS, and the
6055 // shift is the only use, we can pull it out of the shift.
6056 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
6057 bool isValid = true; // Valid only for And, Or, Xor
6058 bool highBitSet = false; // Transform if high bit of constant set?
6060 switch (Op0BO->getOpcode()) {
6061 default: isValid = false; break; // Do not perform transform!
6062 case Instruction::Add:
6063 isValid = isLeftShift;
6065 case Instruction::Or:
6066 case Instruction::Xor:
6069 case Instruction::And:
6074 // If this is a signed shift right, and the high bit is modified
6075 // by the logical operation, do not perform the transformation.
6076 // The highBitSet boolean indicates the value of the high bit of
6077 // the constant which would cause it to be modified for this
6080 if (isValid && !isLeftShift && I.getOpcode() == Instruction::AShr) {
6081 isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
6085 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
6087 Instruction *NewShift =
6088 BinaryOperator::create(I.getOpcode(), Op0BO->getOperand(0), Op1);
6089 InsertNewInstBefore(NewShift, I);
6090 NewShift->takeName(Op0BO);
6092 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
6099 // Find out if this is a shift of a shift by a constant.
6100 BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
6101 if (ShiftOp && !ShiftOp->isShift())
6104 if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
6105 ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
6106 uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
6107 uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
6108 assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
6109 if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
6110 Value *X = ShiftOp->getOperand(0);
6112 uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
6113 if (AmtSum > TypeBits)
6116 const IntegerType *Ty = cast<IntegerType>(I.getType());
6118 // Check for (X << c1) << c2 and (X >> c1) >> c2
6119 if (I.getOpcode() == ShiftOp->getOpcode()) {
6120 return BinaryOperator::create(I.getOpcode(), X,
6121 ConstantInt::get(Ty, AmtSum));
6122 } else if (ShiftOp->getOpcode() == Instruction::LShr &&
6123 I.getOpcode() == Instruction::AShr) {
6124 // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
6125 return BinaryOperator::createLShr(X, ConstantInt::get(Ty, AmtSum));
6126 } else if (ShiftOp->getOpcode() == Instruction::AShr &&
6127 I.getOpcode() == Instruction::LShr) {
6128 // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
6129 Instruction *Shift =
6130 BinaryOperator::createAShr(X, ConstantInt::get(Ty, AmtSum));
6131 InsertNewInstBefore(Shift, I);
6133 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
6134 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6137 // Okay, if we get here, one shift must be left, and the other shift must be
6138 // right. See if the amounts are equal.
6139 if (ShiftAmt1 == ShiftAmt2) {
6140 // If we have ((X >>? C) << C), turn this into X & (-1 << C).
6141 if (I.getOpcode() == Instruction::Shl) {
6142 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
6143 return BinaryOperator::createAnd(X, ConstantInt::get(Mask));
6145 // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
6146 if (I.getOpcode() == Instruction::LShr) {
6147 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
6148 return BinaryOperator::createAnd(X, ConstantInt::get(Mask));
6150 // We can simplify ((X << C) >>s C) into a trunc + sext.
6151 // NOTE: we could do this for any C, but that would make 'unusual' integer
6152 // types. For now, just stick to ones well-supported by the code
6154 const Type *SExtType = 0;
6155 switch (Ty->getBitWidth() - ShiftAmt1) {
6162 SExtType = IntegerType::get(Ty->getBitWidth() - ShiftAmt1);
6167 Instruction *NewTrunc = new TruncInst(X, SExtType, "sext");
6168 InsertNewInstBefore(NewTrunc, I);
6169 return new SExtInst(NewTrunc, Ty);
6171 // Otherwise, we can't handle it yet.
6172 } else if (ShiftAmt1 < ShiftAmt2) {
6173 uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
6175 // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
6176 if (I.getOpcode() == Instruction::Shl) {
6177 assert(ShiftOp->getOpcode() == Instruction::LShr ||
6178 ShiftOp->getOpcode() == Instruction::AShr);
6179 Instruction *Shift =
6180 BinaryOperator::createShl(X, ConstantInt::get(Ty, ShiftDiff));
6181 InsertNewInstBefore(Shift, I);
6183 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
6184 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6187 // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
6188 if (I.getOpcode() == Instruction::LShr) {
6189 assert(ShiftOp->getOpcode() == Instruction::Shl);
6190 Instruction *Shift =
6191 BinaryOperator::createLShr(X, ConstantInt::get(Ty, ShiftDiff));
6192 InsertNewInstBefore(Shift, I);
6194 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
6195 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6198 // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
6200 assert(ShiftAmt2 < ShiftAmt1);
6201 uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
6203 // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
6204 if (I.getOpcode() == Instruction::Shl) {
6205 assert(ShiftOp->getOpcode() == Instruction::LShr ||
6206 ShiftOp->getOpcode() == Instruction::AShr);
6207 Instruction *Shift =
6208 BinaryOperator::create(ShiftOp->getOpcode(), X,
6209 ConstantInt::get(Ty, ShiftDiff));
6210 InsertNewInstBefore(Shift, I);
6212 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
6213 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6216 // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
6217 if (I.getOpcode() == Instruction::LShr) {
6218 assert(ShiftOp->getOpcode() == Instruction::Shl);
6219 Instruction *Shift =
6220 BinaryOperator::createShl(X, ConstantInt::get(Ty, ShiftDiff));
6221 InsertNewInstBefore(Shift, I);
6223 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
6224 return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
6227 // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
6234 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
6235 /// expression. If so, decompose it, returning some value X, such that Val is
6238 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
6240 assert(Val->getType() == Type::Int32Ty && "Unexpected allocation size type!");
6241 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
6242 Offset = CI->getZExtValue();
6244 return ConstantInt::get(Type::Int32Ty, 0);
6245 } else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
6246 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
6247 if (I->getOpcode() == Instruction::Shl) {
6248 // This is a value scaled by '1 << the shift amt'.
6249 Scale = 1U << RHS->getZExtValue();
6251 return I->getOperand(0);
6252 } else if (I->getOpcode() == Instruction::Mul) {
6253 // This value is scaled by 'RHS'.
6254 Scale = RHS->getZExtValue();
6256 return I->getOperand(0);
6257 } else if (I->getOpcode() == Instruction::Add) {
6258 // We have X+C. Check to see if we really have (X*C2)+C1,
6259 // where C1 is divisible by C2.
6262 DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
6263 Offset += RHS->getZExtValue();
6270 // Otherwise, we can't look past this.
6277 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
6278 /// try to eliminate the cast by moving the type information into the alloc.
6279 Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
6280 AllocationInst &AI) {
6281 const PointerType *PTy = cast<PointerType>(CI.getType());
6283 // Remove any uses of AI that are dead.
6284 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
6286 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
6287 Instruction *User = cast<Instruction>(*UI++);
6288 if (isInstructionTriviallyDead(User)) {
6289 while (UI != E && *UI == User)
6290 ++UI; // If this instruction uses AI more than once, don't break UI.
6293 DOUT << "IC: DCE: " << *User;
6294 EraseInstFromFunction(*User);
6298 // Get the type really allocated and the type casted to.
6299 const Type *AllocElTy = AI.getAllocatedType();
6300 const Type *CastElTy = PTy->getElementType();
6301 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
6303 unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
6304 unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
6305 if (CastElTyAlign < AllocElTyAlign) return 0;
6307 // If the allocation has multiple uses, only promote it if we are strictly
6308 // increasing the alignment of the resultant allocation. If we keep it the
6309 // same, we open the door to infinite loops of various kinds.
6310 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
6312 uint64_t AllocElTySize = TD->getABITypeSize(AllocElTy);
6313 uint64_t CastElTySize = TD->getABITypeSize(CastElTy);
6314 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
6316 // See if we can satisfy the modulus by pulling a scale out of the array
6318 unsigned ArraySizeScale;
6320 Value *NumElements = // See if the array size is a decomposable linear expr.
6321 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
6323 // If we can now satisfy the modulus, by using a non-1 scale, we really can
6325 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
6326 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
6328 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
6333 // If the allocation size is constant, form a constant mul expression
6334 Amt = ConstantInt::get(Type::Int32Ty, Scale);
6335 if (isa<ConstantInt>(NumElements))
6336 Amt = Multiply(cast<ConstantInt>(NumElements), cast<ConstantInt>(Amt));
6337 // otherwise multiply the amount and the number of elements
6338 else if (Scale != 1) {
6339 Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
6340 Amt = InsertNewInstBefore(Tmp, AI);
6344 if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
6345 Value *Off = ConstantInt::get(Type::Int32Ty, Offset, true);
6346 Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
6347 Amt = InsertNewInstBefore(Tmp, AI);
6350 AllocationInst *New;
6351 if (isa<MallocInst>(AI))
6352 New = new MallocInst(CastElTy, Amt, AI.getAlignment());
6354 New = new AllocaInst(CastElTy, Amt, AI.getAlignment());
6355 InsertNewInstBefore(New, AI);
6358 // If the allocation has multiple uses, insert a cast and change all things
6359 // that used it to use the new cast. This will also hack on CI, but it will
6361 if (!AI.hasOneUse()) {
6362 AddUsesToWorkList(AI);
6363 // New is the allocation instruction, pointer typed. AI is the original
6364 // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
6365 CastInst *NewCast = new BitCastInst(New, AI.getType(), "tmpcast");
6366 InsertNewInstBefore(NewCast, AI);
6367 AI.replaceAllUsesWith(NewCast);
6369 return ReplaceInstUsesWith(CI, New);
6372 /// CanEvaluateInDifferentType - Return true if we can take the specified value
6373 /// and return it as type Ty without inserting any new casts and without
6374 /// changing the computed value. This is used by code that tries to decide
6375 /// whether promoting or shrinking integer operations to wider or smaller types
6376 /// will allow us to eliminate a truncate or extend.
6378 /// This is a truncation operation if Ty is smaller than V->getType(), or an
6379 /// extension operation if Ty is larger.
6380 static bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
6381 unsigned CastOpc, int &NumCastsRemoved) {
6382 // We can always evaluate constants in another type.
6383 if (isa<ConstantInt>(V))
6386 Instruction *I = dyn_cast<Instruction>(V);
6387 if (!I) return false;
6389 const IntegerType *OrigTy = cast<IntegerType>(V->getType());
6391 // If this is an extension or truncate, we can often eliminate it.
6392 if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
6393 // If this is a cast from the destination type, we can trivially eliminate
6394 // it, and this will remove a cast overall.
6395 if (I->getOperand(0)->getType() == Ty) {
6396 // If the first operand is itself a cast, and is eliminable, do not count
6397 // this as an eliminable cast. We would prefer to eliminate those two
6399 if (!isa<CastInst>(I->getOperand(0)))
6405 // We can't extend or shrink something that has multiple uses: doing so would
6406 // require duplicating the instruction in general, which isn't profitable.
6407 if (!I->hasOneUse()) return false;
6409 switch (I->getOpcode()) {
6410 case Instruction::Add:
6411 case Instruction::Sub:
6412 case Instruction::And:
6413 case Instruction::Or:
6414 case Instruction::Xor:
6415 // These operators can all arbitrarily be extended or truncated.
6416 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
6418 CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
6421 case Instruction::Shl:
6422 // If we are truncating the result of this SHL, and if it's a shift of a
6423 // constant amount, we can always perform a SHL in a smaller type.
6424 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
6425 uint32_t BitWidth = Ty->getBitWidth();
6426 if (BitWidth < OrigTy->getBitWidth() &&
6427 CI->getLimitedValue(BitWidth) < BitWidth)
6428 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
6432 case Instruction::LShr:
6433 // If this is a truncate of a logical shr, we can truncate it to a smaller
6434 // lshr iff we know that the bits we would otherwise be shifting in are
6436 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
6437 uint32_t OrigBitWidth = OrigTy->getBitWidth();
6438 uint32_t BitWidth = Ty->getBitWidth();
6439 if (BitWidth < OrigBitWidth &&
6440 MaskedValueIsZero(I->getOperand(0),
6441 APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
6442 CI->getLimitedValue(BitWidth) < BitWidth) {
6443 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
6448 case Instruction::ZExt:
6449 case Instruction::SExt:
6450 case Instruction::Trunc:
6451 // If this is the same kind of case as our original (e.g. zext+zext), we
6452 // can safely replace it. Note that replacing it does not reduce the number
6453 // of casts in the input.
6454 if (I->getOpcode() == CastOpc)
6459 // TODO: Can handle more cases here.
6466 /// EvaluateInDifferentType - Given an expression that
6467 /// CanEvaluateInDifferentType returns true for, actually insert the code to
6468 /// evaluate the expression.
6469 Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
6471 if (Constant *C = dyn_cast<Constant>(V))
6472 return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
6474 // Otherwise, it must be an instruction.
6475 Instruction *I = cast<Instruction>(V);
6476 Instruction *Res = 0;
6477 switch (I->getOpcode()) {
6478 case Instruction::Add:
6479 case Instruction::Sub:
6480 case Instruction::And:
6481 case Instruction::Or:
6482 case Instruction::Xor:
6483 case Instruction::AShr:
6484 case Instruction::LShr:
6485 case Instruction::Shl: {
6486 Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
6487 Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
6488 Res = BinaryOperator::create((Instruction::BinaryOps)I->getOpcode(),
6489 LHS, RHS, I->getName());
6492 case Instruction::Trunc:
6493 case Instruction::ZExt:
6494 case Instruction::SExt:
6495 // If the source type of the cast is the type we're trying for then we can
6496 // just return the source. There's no need to insert it because it is not
6498 if (I->getOperand(0)->getType() == Ty)
6499 return I->getOperand(0);
6501 // Otherwise, must be the same type of case, so just reinsert a new one.
6502 Res = CastInst::create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
6506 // TODO: Can handle more cases here.
6507 assert(0 && "Unreachable!");
6511 return InsertNewInstBefore(Res, *I);
6514 /// @brief Implement the transforms common to all CastInst visitors.
6515 Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
6516 Value *Src = CI.getOperand(0);
6518 // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
6519 // eliminate it now.
6520 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
6521 if (Instruction::CastOps opc =
6522 isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
6523 // The first cast (CSrc) is eliminable so we need to fix up or replace
6524 // the second cast (CI). CSrc will then have a good chance of being dead.
6525 return CastInst::create(opc, CSrc->getOperand(0), CI.getType());
6529 // If we are casting a select then fold the cast into the select
6530 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
6531 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
6534 // If we are casting a PHI then fold the cast into the PHI
6535 if (isa<PHINode>(Src))
6536 if (Instruction *NV = FoldOpIntoPhi(CI))
6542 /// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
6543 Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
6544 Value *Src = CI.getOperand(0);
6546 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
6547 // If casting the result of a getelementptr instruction with no offset, turn
6548 // this into a cast of the original pointer!
6549 if (GEP->hasAllZeroIndices()) {
6550 // Changing the cast operand is usually not a good idea but it is safe
6551 // here because the pointer operand is being replaced with another
6552 // pointer operand so the opcode doesn't need to change.
6554 CI.setOperand(0, GEP->getOperand(0));
6558 // If the GEP has a single use, and the base pointer is a bitcast, and the
6559 // GEP computes a constant offset, see if we can convert these three
6560 // instructions into fewer. This typically happens with unions and other
6561 // non-type-safe code.
6562 if (GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
6563 if (GEP->hasAllConstantIndices()) {
6564 // We are guaranteed to get a constant from EmitGEPOffset.
6565 ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, CI, *this));
6566 int64_t Offset = OffsetV->getSExtValue();
6568 // Get the base pointer input of the bitcast, and the type it points to.
6569 Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
6570 const Type *GEPIdxTy =
6571 cast<PointerType>(OrigBase->getType())->getElementType();
6572 if (GEPIdxTy->isSized()) {
6573 SmallVector<Value*, 8> NewIndices;
6575 // Start with the index over the outer type. Note that the type size
6576 // might be zero (even if the offset isn't zero) if the indexed type
6577 // is something like [0 x {int, int}]
6578 const Type *IntPtrTy = TD->getIntPtrType();
6579 int64_t FirstIdx = 0;
6580 if (int64_t TySize = TD->getABITypeSize(GEPIdxTy)) {
6581 FirstIdx = Offset/TySize;
6584 // Handle silly modulus not returning values values [0..TySize).
6588 assert(Offset >= 0);
6590 assert((uint64_t)Offset < (uint64_t)TySize &&"Out of range offset");
6593 NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
6595 // Index into the types. If we fail, set OrigBase to null.
6597 if (const StructType *STy = dyn_cast<StructType>(GEPIdxTy)) {
6598 const StructLayout *SL = TD->getStructLayout(STy);
6599 if (Offset < (int64_t)SL->getSizeInBytes()) {
6600 unsigned Elt = SL->getElementContainingOffset(Offset);
6601 NewIndices.push_back(ConstantInt::get(Type::Int32Ty, Elt));
6603 Offset -= SL->getElementOffset(Elt);
6604 GEPIdxTy = STy->getElementType(Elt);
6606 // Otherwise, we can't index into this, bail out.
6610 } else if (isa<ArrayType>(GEPIdxTy) || isa<VectorType>(GEPIdxTy)) {
6611 const SequentialType *STy = cast<SequentialType>(GEPIdxTy);
6612 if (uint64_t EltSize = TD->getABITypeSize(STy->getElementType())){
6613 NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
6616 NewIndices.push_back(ConstantInt::get(IntPtrTy, 0));
6618 GEPIdxTy = STy->getElementType();
6620 // Otherwise, we can't index into this, bail out.
6626 // If we were able to index down into an element, create the GEP
6627 // and bitcast the result. This eliminates one bitcast, potentially
6629 Instruction *NGEP = new GetElementPtrInst(OrigBase,
6631 NewIndices.end(), "");
6632 InsertNewInstBefore(NGEP, CI);
6633 NGEP->takeName(GEP);
6635 if (isa<BitCastInst>(CI))
6636 return new BitCastInst(NGEP, CI.getType());
6637 assert(isa<PtrToIntInst>(CI));
6638 return new PtrToIntInst(NGEP, CI.getType());
6645 return commonCastTransforms(CI);
6650 /// Only the TRUNC, ZEXT, SEXT, and BITCAST can both operand and result as
6651 /// integer types. This function implements the common transforms for all those
6653 /// @brief Implement the transforms common to CastInst with integer operands
6654 Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
6655 if (Instruction *Result = commonCastTransforms(CI))
6658 Value *Src = CI.getOperand(0);
6659 const Type *SrcTy = Src->getType();
6660 const Type *DestTy = CI.getType();
6661 uint32_t SrcBitSize = SrcTy->getPrimitiveSizeInBits();
6662 uint32_t DestBitSize = DestTy->getPrimitiveSizeInBits();
6664 // See if we can simplify any instructions used by the LHS whose sole
6665 // purpose is to compute bits we don't care about.
6666 APInt KnownZero(DestBitSize, 0), KnownOne(DestBitSize, 0);
6667 if (SimplifyDemandedBits(&CI, APInt::getAllOnesValue(DestBitSize),
6668 KnownZero, KnownOne))
6671 // If the source isn't an instruction or has more than one use then we
6672 // can't do anything more.
6673 Instruction *SrcI = dyn_cast<Instruction>(Src);
6674 if (!SrcI || !Src->hasOneUse())
6677 // Attempt to propagate the cast into the instruction for int->int casts.
6678 int NumCastsRemoved = 0;
6679 if (!isa<BitCastInst>(CI) &&
6680 CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy),
6681 CI.getOpcode(), NumCastsRemoved)) {
6682 // If this cast is a truncate, evaluting in a different type always
6683 // eliminates the cast, so it is always a win. If this is a zero-extension,
6684 // we need to do an AND to maintain the clear top-part of the computation,
6685 // so we require that the input have eliminated at least one cast. If this
6686 // is a sign extension, we insert two new casts (to do the extension) so we
6687 // require that two casts have been eliminated.
6689 switch (CI.getOpcode()) {
6691 // All the others use floating point so we shouldn't actually
6692 // get here because of the check above.
6693 assert(0 && "Unknown cast type");
6694 case Instruction::Trunc:
6697 case Instruction::ZExt:
6698 DoXForm = NumCastsRemoved >= 1;
6700 case Instruction::SExt:
6701 DoXForm = NumCastsRemoved >= 2;
6706 Value *Res = EvaluateInDifferentType(SrcI, DestTy,
6707 CI.getOpcode() == Instruction::SExt);
6708 assert(Res->getType() == DestTy);
6709 switch (CI.getOpcode()) {
6710 default: assert(0 && "Unknown cast type!");
6711 case Instruction::Trunc:
6712 case Instruction::BitCast:
6713 // Just replace this cast with the result.
6714 return ReplaceInstUsesWith(CI, Res);
6715 case Instruction::ZExt: {
6716 // We need to emit an AND to clear the high bits.
6717 assert(SrcBitSize < DestBitSize && "Not a zext?");
6718 Constant *C = ConstantInt::get(APInt::getLowBitsSet(DestBitSize,
6720 return BinaryOperator::createAnd(Res, C);
6722 case Instruction::SExt:
6723 // We need to emit a cast to truncate, then a cast to sext.
6724 return CastInst::create(Instruction::SExt,
6725 InsertCastBefore(Instruction::Trunc, Res, Src->getType(),
6731 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
6732 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
6734 switch (SrcI->getOpcode()) {
6735 case Instruction::Add:
6736 case Instruction::Mul:
6737 case Instruction::And:
6738 case Instruction::Or:
6739 case Instruction::Xor:
6740 // If we are discarding information, rewrite.
6741 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
6742 // Don't insert two casts if they cannot be eliminated. We allow
6743 // two casts to be inserted if the sizes are the same. This could
6744 // only be converting signedness, which is a noop.
6745 if (DestBitSize == SrcBitSize ||
6746 !ValueRequiresCast(CI.getOpcode(), Op1, DestTy,TD) ||
6747 !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
6748 Instruction::CastOps opcode = CI.getOpcode();
6749 Value *Op0c = InsertOperandCastBefore(opcode, Op0, DestTy, SrcI);
6750 Value *Op1c = InsertOperandCastBefore(opcode, Op1, DestTy, SrcI);
6751 return BinaryOperator::create(
6752 cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
6756 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
6757 if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
6758 SrcI->getOpcode() == Instruction::Xor &&
6759 Op1 == ConstantInt::getTrue() &&
6760 (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
6761 Value *New = InsertOperandCastBefore(Instruction::ZExt, Op0, DestTy, &CI);
6762 return BinaryOperator::createXor(New, ConstantInt::get(CI.getType(), 1));
6765 case Instruction::SDiv:
6766 case Instruction::UDiv:
6767 case Instruction::SRem:
6768 case Instruction::URem:
6769 // If we are just changing the sign, rewrite.
6770 if (DestBitSize == SrcBitSize) {
6771 // Don't insert two casts if they cannot be eliminated. We allow
6772 // two casts to be inserted if the sizes are the same. This could
6773 // only be converting signedness, which is a noop.
6774 if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
6775 !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
6776 Value *Op0c = InsertOperandCastBefore(Instruction::BitCast,
6778 Value *Op1c = InsertOperandCastBefore(Instruction::BitCast,
6780 return BinaryOperator::create(
6781 cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
6786 case Instruction::Shl:
6787 // Allow changing the sign of the source operand. Do not allow
6788 // changing the size of the shift, UNLESS the shift amount is a
6789 // constant. We must not change variable sized shifts to a smaller
6790 // size, because it is undefined to shift more bits out than exist
6792 if (DestBitSize == SrcBitSize ||
6793 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
6794 Instruction::CastOps opcode = (DestBitSize == SrcBitSize ?
6795 Instruction::BitCast : Instruction::Trunc);
6796 Value *Op0c = InsertOperandCastBefore(opcode, Op0, DestTy, SrcI);
6797 Value *Op1c = InsertOperandCastBefore(opcode, Op1, DestTy, SrcI);
6798 return BinaryOperator::createShl(Op0c, Op1c);
6801 case Instruction::AShr:
6802 // If this is a signed shr, and if all bits shifted in are about to be
6803 // truncated off, turn it into an unsigned shr to allow greater
6805 if (DestBitSize < SrcBitSize &&
6806 isa<ConstantInt>(Op1)) {
6807 uint32_t ShiftAmt = cast<ConstantInt>(Op1)->getLimitedValue(SrcBitSize);
6808 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
6809 // Insert the new logical shift right.
6810 return BinaryOperator::createLShr(Op0, Op1);
6818 Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
6819 if (Instruction *Result = commonIntCastTransforms(CI))
6822 Value *Src = CI.getOperand(0);
6823 const Type *Ty = CI.getType();
6824 uint32_t DestBitWidth = Ty->getPrimitiveSizeInBits();
6825 uint32_t SrcBitWidth = cast<IntegerType>(Src->getType())->getBitWidth();
6827 if (Instruction *SrcI = dyn_cast<Instruction>(Src)) {
6828 switch (SrcI->getOpcode()) {
6830 case Instruction::LShr:
6831 // We can shrink lshr to something smaller if we know the bits shifted in
6832 // are already zeros.
6833 if (ConstantInt *ShAmtV = dyn_cast<ConstantInt>(SrcI->getOperand(1))) {
6834 uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
6836 // Get a mask for the bits shifting in.
6837 APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
6838 Value* SrcIOp0 = SrcI->getOperand(0);
6839 if (SrcI->hasOneUse() && MaskedValueIsZero(SrcIOp0, Mask)) {
6840 if (ShAmt >= DestBitWidth) // All zeros.
6841 return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
6843 // Okay, we can shrink this. Truncate the input, then return a new
6845 Value *V1 = InsertCastBefore(Instruction::Trunc, SrcIOp0, Ty, CI);
6846 Value *V2 = InsertCastBefore(Instruction::Trunc, SrcI->getOperand(1),
6848 return BinaryOperator::createLShr(V1, V2);
6850 } else { // This is a variable shr.
6852 // Turn 'trunc (lshr X, Y) to bool' into '(X & (1 << Y)) != 0'. This is
6853 // more LLVM instructions, but allows '1 << Y' to be hoisted if
6854 // loop-invariant and CSE'd.
6855 if (CI.getType() == Type::Int1Ty && SrcI->hasOneUse()) {
6856 Value *One = ConstantInt::get(SrcI->getType(), 1);
6858 Value *V = InsertNewInstBefore(
6859 BinaryOperator::createShl(One, SrcI->getOperand(1),
6861 V = InsertNewInstBefore(BinaryOperator::createAnd(V,
6862 SrcI->getOperand(0),
6864 Value *Zero = Constant::getNullValue(V->getType());
6865 return new ICmpInst(ICmpInst::ICMP_NE, V, Zero);
6875 Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
6876 // If one of the common conversion will work ..
6877 if (Instruction *Result = commonIntCastTransforms(CI))
6880 Value *Src = CI.getOperand(0);
6882 // If this is a cast of a cast
6883 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
6884 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
6885 // types and if the sizes are just right we can convert this into a logical
6886 // 'and' which will be much cheaper than the pair of casts.
6887 if (isa<TruncInst>(CSrc)) {
6888 // Get the sizes of the types involved
6889 Value *A = CSrc->getOperand(0);
6890 uint32_t SrcSize = A->getType()->getPrimitiveSizeInBits();
6891 uint32_t MidSize = CSrc->getType()->getPrimitiveSizeInBits();
6892 uint32_t DstSize = CI.getType()->getPrimitiveSizeInBits();
6893 // If we're actually extending zero bits and the trunc is a no-op
6894 if (MidSize < DstSize && SrcSize == DstSize) {
6895 // Replace both of the casts with an And of the type mask.
6896 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
6897 Constant *AndConst = ConstantInt::get(AndValue);
6899 BinaryOperator::createAnd(CSrc->getOperand(0), AndConst);
6900 // Unfortunately, if the type changed, we need to cast it back.
6901 if (And->getType() != CI.getType()) {
6902 And->setName(CSrc->getName()+".mask");
6903 InsertNewInstBefore(And, CI);
6904 And = CastInst::createIntegerCast(And, CI.getType(), false/*ZExt*/);
6911 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) {
6912 // If we are just checking for a icmp eq of a single bit and zext'ing it
6913 // to an integer, then shift the bit to the appropriate place and then
6914 // cast to integer to avoid the comparison.
6915 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
6916 const APInt &Op1CV = Op1C->getValue();
6918 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
6919 // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
6920 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
6921 (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())){
6922 Value *In = ICI->getOperand(0);
6923 Value *Sh = ConstantInt::get(In->getType(),
6924 In->getType()->getPrimitiveSizeInBits()-1);
6925 In = InsertNewInstBefore(BinaryOperator::createLShr(In, Sh,
6926 In->getName()+".lobit"),
6928 if (In->getType() != CI.getType())
6929 In = CastInst::createIntegerCast(In, CI.getType(),
6930 false/*ZExt*/, "tmp", &CI);
6932 if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
6933 Constant *One = ConstantInt::get(In->getType(), 1);
6934 In = InsertNewInstBefore(BinaryOperator::createXor(In, One,
6935 In->getName()+".not"),
6939 return ReplaceInstUsesWith(CI, In);
6944 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
6945 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
6946 // zext (X == 1) to i32 --> X iff X has only the low bit set.
6947 // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
6948 // zext (X != 0) to i32 --> X iff X has only the low bit set.
6949 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
6950 // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
6951 // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
6952 if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
6953 // This only works for EQ and NE
6954 ICI->isEquality()) {
6955 // If Op1C some other power of two, convert:
6956 uint32_t BitWidth = Op1C->getType()->getBitWidth();
6957 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
6958 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
6959 ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
6961 APInt KnownZeroMask(~KnownZero);
6962 if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
6963 bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
6964 if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
6965 // (X&4) == 2 --> false
6966 // (X&4) != 2 --> true
6967 Constant *Res = ConstantInt::get(Type::Int1Ty, isNE);
6968 Res = ConstantExpr::getZExt(Res, CI.getType());
6969 return ReplaceInstUsesWith(CI, Res);
6972 uint32_t ShiftAmt = KnownZeroMask.logBase2();
6973 Value *In = ICI->getOperand(0);
6975 // Perform a logical shr by shiftamt.
6976 // Insert the shift to put the result in the low bit.
6977 In = InsertNewInstBefore(
6978 BinaryOperator::createLShr(In,
6979 ConstantInt::get(In->getType(), ShiftAmt),
6980 In->getName()+".lobit"), CI);
6983 if ((Op1CV != 0) == isNE) { // Toggle the low bit.
6984 Constant *One = ConstantInt::get(In->getType(), 1);
6985 In = BinaryOperator::createXor(In, One, "tmp");
6986 InsertNewInstBefore(cast<Instruction>(In), CI);
6989 if (CI.getType() == In->getType())
6990 return ReplaceInstUsesWith(CI, In);
6992 return CastInst::createIntegerCast(In, CI.getType(), false/*ZExt*/);
7000 Instruction *InstCombiner::visitSExt(SExtInst &CI) {
7001 if (Instruction *I = commonIntCastTransforms(CI))
7004 Value *Src = CI.getOperand(0);
7006 // sext (x <s 0) -> ashr x, 31 -> all ones if signed
7007 // sext (x >s -1) -> ashr x, 31 -> all ones if not signed
7008 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) {
7009 // If we are just checking for a icmp eq of a single bit and zext'ing it
7010 // to an integer, then shift the bit to the appropriate place and then
7011 // cast to integer to avoid the comparison.
7012 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
7013 const APInt &Op1CV = Op1C->getValue();
7015 // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
7016 // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
7017 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
7018 (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())){
7019 Value *In = ICI->getOperand(0);
7020 Value *Sh = ConstantInt::get(In->getType(),
7021 In->getType()->getPrimitiveSizeInBits()-1);
7022 In = InsertNewInstBefore(BinaryOperator::createAShr(In, Sh,
7023 In->getName()+".lobit"),
7025 if (In->getType() != CI.getType())
7026 In = CastInst::createIntegerCast(In, CI.getType(),
7027 true/*SExt*/, "tmp", &CI);
7029 if (ICI->getPredicate() == ICmpInst::ICMP_SGT)
7030 In = InsertNewInstBefore(BinaryOperator::createNot(In,
7031 In->getName()+".not"), CI);
7033 return ReplaceInstUsesWith(CI, In);
7041 Instruction *InstCombiner::visitFPTrunc(CastInst &CI) {
7042 return commonCastTransforms(CI);
7045 Instruction *InstCombiner::visitFPExt(CastInst &CI) {
7046 return commonCastTransforms(CI);
7049 Instruction *InstCombiner::visitFPToUI(CastInst &CI) {
7050 return commonCastTransforms(CI);
7053 Instruction *InstCombiner::visitFPToSI(CastInst &CI) {
7054 return commonCastTransforms(CI);
7057 Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
7058 return commonCastTransforms(CI);
7061 Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
7062 return commonCastTransforms(CI);
7065 Instruction *InstCombiner::visitPtrToInt(CastInst &CI) {
7066 return commonPointerCastTransforms(CI);
7069 Instruction *InstCombiner::visitIntToPtr(CastInst &CI) {
7070 return commonCastTransforms(CI);
7073 Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
7074 // If the operands are integer typed then apply the integer transforms,
7075 // otherwise just apply the common ones.
7076 Value *Src = CI.getOperand(0);
7077 const Type *SrcTy = Src->getType();
7078 const Type *DestTy = CI.getType();
7080 if (SrcTy->isInteger() && DestTy->isInteger()) {
7081 if (Instruction *Result = commonIntCastTransforms(CI))
7083 } else if (isa<PointerType>(SrcTy)) {
7084 if (Instruction *I = commonPointerCastTransforms(CI))
7087 if (Instruction *Result = commonCastTransforms(CI))
7092 // Get rid of casts from one type to the same type. These are useless and can
7093 // be replaced by the operand.
7094 if (DestTy == Src->getType())
7095 return ReplaceInstUsesWith(CI, Src);
7097 if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
7098 const PointerType *SrcPTy = cast<PointerType>(SrcTy);
7099 const Type *DstElTy = DstPTy->getElementType();
7100 const Type *SrcElTy = SrcPTy->getElementType();
7102 // If we are casting a malloc or alloca to a pointer to a type of the same
7103 // size, rewrite the allocation instruction to allocate the "right" type.
7104 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
7105 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
7108 // If the source and destination are pointers, and this cast is equivalent
7109 // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
7110 // This can enhance SROA and other transforms that want type-safe pointers.
7111 Constant *ZeroUInt = Constant::getNullValue(Type::Int32Ty);
7112 unsigned NumZeros = 0;
7113 while (SrcElTy != DstElTy &&
7114 isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
7115 SrcElTy->getNumContainedTypes() /* not "{}" */) {
7116 SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
7120 // If we found a path from the src to dest, create the getelementptr now.
7121 if (SrcElTy == DstElTy) {
7122 SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
7123 return new GetElementPtrInst(Src, Idxs.begin(), Idxs.end(), "",
7124 ((Instruction*) NULL));
7128 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
7129 if (SVI->hasOneUse()) {
7130 // Okay, we have (bitconvert (shuffle ..)). Check to see if this is
7131 // a bitconvert to a vector with the same # elts.
7132 if (isa<VectorType>(DestTy) &&
7133 cast<VectorType>(DestTy)->getNumElements() ==
7134 SVI->getType()->getNumElements()) {
7136 // If either of the operands is a cast from CI.getType(), then
7137 // evaluating the shuffle in the casted destination's type will allow
7138 // us to eliminate at least one cast.
7139 if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
7140 Tmp->getOperand(0)->getType() == DestTy) ||
7141 ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
7142 Tmp->getOperand(0)->getType() == DestTy)) {
7143 Value *LHS = InsertOperandCastBefore(Instruction::BitCast,
7144 SVI->getOperand(0), DestTy, &CI);
7145 Value *RHS = InsertOperandCastBefore(Instruction::BitCast,
7146 SVI->getOperand(1), DestTy, &CI);
7147 // Return a new shuffle vector. Use the same element ID's, as we
7148 // know the vector types match #elts.
7149 return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
7157 /// GetSelectFoldableOperands - We want to turn code that looks like this:
7159 /// %D = select %cond, %C, %A
7161 /// %C = select %cond, %B, 0
7164 /// Assuming that the specified instruction is an operand to the select, return
7165 /// a bitmask indicating which operands of this instruction are foldable if they
7166 /// equal the other incoming value of the select.
7168 static unsigned GetSelectFoldableOperands(Instruction *I) {
7169 switch (I->getOpcode()) {
7170 case Instruction::Add:
7171 case Instruction::Mul:
7172 case Instruction::And:
7173 case Instruction::Or:
7174 case Instruction::Xor:
7175 return 3; // Can fold through either operand.
7176 case Instruction::Sub: // Can only fold on the amount subtracted.
7177 case Instruction::Shl: // Can only fold on the shift amount.
7178 case Instruction::LShr:
7179 case Instruction::AShr:
7182 return 0; // Cannot fold
7186 /// GetSelectFoldableConstant - For the same transformation as the previous
7187 /// function, return the identity constant that goes into the select.
7188 static Constant *GetSelectFoldableConstant(Instruction *I) {
7189 switch (I->getOpcode()) {
7190 default: assert(0 && "This cannot happen!"); abort();
7191 case Instruction::Add:
7192 case Instruction::Sub:
7193 case Instruction::Or:
7194 case Instruction::Xor:
7195 case Instruction::Shl:
7196 case Instruction::LShr:
7197 case Instruction::AShr:
7198 return Constant::getNullValue(I->getType());
7199 case Instruction::And:
7200 return Constant::getAllOnesValue(I->getType());
7201 case Instruction::Mul:
7202 return ConstantInt::get(I->getType(), 1);
7206 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
7207 /// have the same opcode and only one use each. Try to simplify this.
7208 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
7210 if (TI->getNumOperands() == 1) {
7211 // If this is a non-volatile load or a cast from the same type,
7214 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
7217 return 0; // unknown unary op.
7220 // Fold this by inserting a select from the input values.
7221 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
7222 FI->getOperand(0), SI.getName()+".v");
7223 InsertNewInstBefore(NewSI, SI);
7224 return CastInst::create(Instruction::CastOps(TI->getOpcode()), NewSI,
7228 // Only handle binary operators here.
7229 if (!isa<BinaryOperator>(TI))
7232 // Figure out if the operations have any operands in common.
7233 Value *MatchOp, *OtherOpT, *OtherOpF;
7235 if (TI->getOperand(0) == FI->getOperand(0)) {
7236 MatchOp = TI->getOperand(0);
7237 OtherOpT = TI->getOperand(1);
7238 OtherOpF = FI->getOperand(1);
7239 MatchIsOpZero = true;
7240 } else if (TI->getOperand(1) == FI->getOperand(1)) {
7241 MatchOp = TI->getOperand(1);
7242 OtherOpT = TI->getOperand(0);
7243 OtherOpF = FI->getOperand(0);
7244 MatchIsOpZero = false;
7245 } else if (!TI->isCommutative()) {
7247 } else if (TI->getOperand(0) == FI->getOperand(1)) {
7248 MatchOp = TI->getOperand(0);
7249 OtherOpT = TI->getOperand(1);
7250 OtherOpF = FI->getOperand(0);
7251 MatchIsOpZero = true;
7252 } else if (TI->getOperand(1) == FI->getOperand(0)) {
7253 MatchOp = TI->getOperand(1);
7254 OtherOpT = TI->getOperand(0);
7255 OtherOpF = FI->getOperand(1);
7256 MatchIsOpZero = true;
7261 // If we reach here, they do have operations in common.
7262 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
7263 OtherOpF, SI.getName()+".v");
7264 InsertNewInstBefore(NewSI, SI);
7266 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
7268 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
7270 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
7272 assert(0 && "Shouldn't get here");
7276 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
7277 Value *CondVal = SI.getCondition();
7278 Value *TrueVal = SI.getTrueValue();
7279 Value *FalseVal = SI.getFalseValue();
7281 // select true, X, Y -> X
7282 // select false, X, Y -> Y
7283 if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
7284 return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
7286 // select C, X, X -> X
7287 if (TrueVal == FalseVal)
7288 return ReplaceInstUsesWith(SI, TrueVal);
7290 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
7291 return ReplaceInstUsesWith(SI, FalseVal);
7292 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
7293 return ReplaceInstUsesWith(SI, TrueVal);
7294 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
7295 if (isa<Constant>(TrueVal))
7296 return ReplaceInstUsesWith(SI, TrueVal);
7298 return ReplaceInstUsesWith(SI, FalseVal);
7301 if (SI.getType() == Type::Int1Ty) {
7302 if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
7303 if (C->getZExtValue()) {
7304 // Change: A = select B, true, C --> A = or B, C
7305 return BinaryOperator::createOr(CondVal, FalseVal);
7307 // Change: A = select B, false, C --> A = and !B, C
7309 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
7310 "not."+CondVal->getName()), SI);
7311 return BinaryOperator::createAnd(NotCond, FalseVal);
7313 } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
7314 if (C->getZExtValue() == false) {
7315 // Change: A = select B, C, false --> A = and B, C
7316 return BinaryOperator::createAnd(CondVal, TrueVal);
7318 // Change: A = select B, C, true --> A = or !B, C
7320 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
7321 "not."+CondVal->getName()), SI);
7322 return BinaryOperator::createOr(NotCond, TrueVal);
7327 // Selecting between two integer constants?
7328 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
7329 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
7330 // select C, 1, 0 -> zext C to int
7331 if (FalseValC->isZero() && TrueValC->getValue() == 1) {
7332 return CastInst::create(Instruction::ZExt, CondVal, SI.getType());
7333 } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
7334 // select C, 0, 1 -> zext !C to int
7336 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
7337 "not."+CondVal->getName()), SI);
7338 return CastInst::create(Instruction::ZExt, NotCond, SI.getType());
7341 // FIXME: Turn select 0/-1 and -1/0 into sext from condition!
7343 if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
7345 // (x <s 0) ? -1 : 0 -> ashr x, 31
7346 if (TrueValC->isAllOnesValue() && FalseValC->isZero())
7347 if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) {
7348 if (IC->getPredicate() == ICmpInst::ICMP_SLT && CmpCst->isZero()) {
7349 // The comparison constant and the result are not neccessarily the
7350 // same width. Make an all-ones value by inserting a AShr.
7351 Value *X = IC->getOperand(0);
7352 uint32_t Bits = X->getType()->getPrimitiveSizeInBits();
7353 Constant *ShAmt = ConstantInt::get(X->getType(), Bits-1);
7354 Instruction *SRA = BinaryOperator::create(Instruction::AShr, X,
7356 InsertNewInstBefore(SRA, SI);
7358 // Finally, convert to the type of the select RHS. We figure out
7359 // if this requires a SExt, Trunc or BitCast based on the sizes.
7360 Instruction::CastOps opc = Instruction::BitCast;
7361 uint32_t SRASize = SRA->getType()->getPrimitiveSizeInBits();
7362 uint32_t SISize = SI.getType()->getPrimitiveSizeInBits();
7363 if (SRASize < SISize)
7364 opc = Instruction::SExt;
7365 else if (SRASize > SISize)
7366 opc = Instruction::Trunc;
7367 return CastInst::create(opc, SRA, SI.getType());
7372 // If one of the constants is zero (we know they can't both be) and we
7373 // have an icmp instruction with zero, and we have an 'and' with the
7374 // non-constant value, eliminate this whole mess. This corresponds to
7375 // cases like this: ((X & 27) ? 27 : 0)
7376 if (TrueValC->isZero() || FalseValC->isZero())
7377 if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
7378 cast<Constant>(IC->getOperand(1))->isNullValue())
7379 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
7380 if (ICA->getOpcode() == Instruction::And &&
7381 isa<ConstantInt>(ICA->getOperand(1)) &&
7382 (ICA->getOperand(1) == TrueValC ||
7383 ICA->getOperand(1) == FalseValC) &&
7384 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
7385 // Okay, now we know that everything is set up, we just don't
7386 // know whether we have a icmp_ne or icmp_eq and whether the
7387 // true or false val is the zero.
7388 bool ShouldNotVal = !TrueValC->isZero();
7389 ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
7392 V = InsertNewInstBefore(BinaryOperator::create(
7393 Instruction::Xor, V, ICA->getOperand(1)), SI);
7394 return ReplaceInstUsesWith(SI, V);
7399 // See if we are selecting two values based on a comparison of the two values.
7400 if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
7401 if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
7402 // Transform (X == Y) ? X : Y -> Y
7403 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
7404 // This is not safe in general for floating point:
7405 // consider X== -0, Y== +0.
7406 // It becomes safe if either operand is a nonzero constant.
7407 ConstantFP *CFPt, *CFPf;
7408 if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
7409 !CFPt->getValueAPF().isZero()) ||
7410 ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
7411 !CFPf->getValueAPF().isZero()))
7412 return ReplaceInstUsesWith(SI, FalseVal);
7414 // Transform (X != Y) ? X : Y -> X
7415 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
7416 return ReplaceInstUsesWith(SI, TrueVal);
7417 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7419 } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
7420 // Transform (X == Y) ? Y : X -> X
7421 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
7422 // This is not safe in general for floating point:
7423 // consider X== -0, Y== +0.
7424 // It becomes safe if either operand is a nonzero constant.
7425 ConstantFP *CFPt, *CFPf;
7426 if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
7427 !CFPt->getValueAPF().isZero()) ||
7428 ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
7429 !CFPf->getValueAPF().isZero()))
7430 return ReplaceInstUsesWith(SI, FalseVal);
7432 // Transform (X != Y) ? Y : X -> Y
7433 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
7434 return ReplaceInstUsesWith(SI, TrueVal);
7435 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7439 // See if we are selecting two values based on a comparison of the two values.
7440 if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal)) {
7441 if (ICI->getOperand(0) == TrueVal && ICI->getOperand(1) == FalseVal) {
7442 // Transform (X == Y) ? X : Y -> Y
7443 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
7444 return ReplaceInstUsesWith(SI, FalseVal);
7445 // Transform (X != Y) ? X : Y -> X
7446 if (ICI->getPredicate() == ICmpInst::ICMP_NE)
7447 return ReplaceInstUsesWith(SI, TrueVal);
7448 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7450 } else if (ICI->getOperand(0) == FalseVal && ICI->getOperand(1) == TrueVal){
7451 // Transform (X == Y) ? Y : X -> X
7452 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
7453 return ReplaceInstUsesWith(SI, FalseVal);
7454 // Transform (X != Y) ? Y : X -> Y
7455 if (ICI->getPredicate() == ICmpInst::ICMP_NE)
7456 return ReplaceInstUsesWith(SI, TrueVal);
7457 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
7461 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
7462 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
7463 if (TI->hasOneUse() && FI->hasOneUse()) {
7464 Instruction *AddOp = 0, *SubOp = 0;
7466 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
7467 if (TI->getOpcode() == FI->getOpcode())
7468 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
7471 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
7472 // even legal for FP.
7473 if (TI->getOpcode() == Instruction::Sub &&
7474 FI->getOpcode() == Instruction::Add) {
7475 AddOp = FI; SubOp = TI;
7476 } else if (FI->getOpcode() == Instruction::Sub &&
7477 TI->getOpcode() == Instruction::Add) {
7478 AddOp = TI; SubOp = FI;
7482 Value *OtherAddOp = 0;
7483 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
7484 OtherAddOp = AddOp->getOperand(1);
7485 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
7486 OtherAddOp = AddOp->getOperand(0);
7490 // So at this point we know we have (Y -> OtherAddOp):
7491 // select C, (add X, Y), (sub X, Z)
7492 Value *NegVal; // Compute -Z
7493 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
7494 NegVal = ConstantExpr::getNeg(C);
7496 NegVal = InsertNewInstBefore(
7497 BinaryOperator::createNeg(SubOp->getOperand(1), "tmp"), SI);
7500 Value *NewTrueOp = OtherAddOp;
7501 Value *NewFalseOp = NegVal;
7503 std::swap(NewTrueOp, NewFalseOp);
7504 Instruction *NewSel =
7505 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
7507 NewSel = InsertNewInstBefore(NewSel, SI);
7508 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
7513 // See if we can fold the select into one of our operands.
7514 if (SI.getType()->isInteger()) {
7515 // See the comment above GetSelectFoldableOperands for a description of the
7516 // transformation we are doing here.
7517 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
7518 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
7519 !isa<Constant>(FalseVal))
7520 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
7521 unsigned OpToFold = 0;
7522 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
7524 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
7529 Constant *C = GetSelectFoldableConstant(TVI);
7530 Instruction *NewSel =
7531 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C);
7532 InsertNewInstBefore(NewSel, SI);
7533 NewSel->takeName(TVI);
7534 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
7535 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
7537 assert(0 && "Unknown instruction!!");
7542 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
7543 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
7544 !isa<Constant>(TrueVal))
7545 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
7546 unsigned OpToFold = 0;
7547 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
7549 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
7554 Constant *C = GetSelectFoldableConstant(FVI);
7555 Instruction *NewSel =
7556 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold));
7557 InsertNewInstBefore(NewSel, SI);
7558 NewSel->takeName(FVI);
7559 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
7560 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
7562 assert(0 && "Unknown instruction!!");
7567 if (BinaryOperator::isNot(CondVal)) {
7568 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
7569 SI.setOperand(1, FalseVal);
7570 SI.setOperand(2, TrueVal);
7577 /// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
7578 /// we can determine, return it, otherwise return 0. If PrefAlign is specified,
7579 /// and it is more than the alignment of the ultimate object, see if we can
7580 /// increase the alignment of the ultimate object, making this check succeed.
7581 static unsigned GetOrEnforceKnownAlignment(Value *V, TargetData *TD,
7582 unsigned PrefAlign = 0) {
7583 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
7584 unsigned Align = GV->getAlignment();
7585 if (Align == 0 && TD && GV->getType()->getElementType()->isSized())
7586 Align = TD->getPrefTypeAlignment(GV->getType()->getElementType());
7588 // If there is a large requested alignment and we can, bump up the alignment
7590 if (PrefAlign > Align && GV->hasInitializer()) {
7591 GV->setAlignment(PrefAlign);
7595 } else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
7596 unsigned Align = AI->getAlignment();
7597 if (Align == 0 && TD) {
7598 if (isa<AllocaInst>(AI))
7599 Align = TD->getPrefTypeAlignment(AI->getType()->getElementType());
7600 else if (isa<MallocInst>(AI)) {
7601 // Malloc returns maximally aligned memory.
7602 Align = TD->getABITypeAlignment(AI->getType()->getElementType());
7605 (unsigned)TD->getABITypeAlignment(Type::DoubleTy));
7608 (unsigned)TD->getABITypeAlignment(Type::Int64Ty));
7612 // If there is a requested alignment and if this is an alloca, round up. We
7613 // don't do this for malloc, because some systems can't respect the request.
7614 if (PrefAlign > Align && isa<AllocaInst>(AI)) {
7615 AI->setAlignment(PrefAlign);
7619 } else if (isa<BitCastInst>(V) ||
7620 (isa<ConstantExpr>(V) &&
7621 cast<ConstantExpr>(V)->getOpcode() == Instruction::BitCast)) {
7622 return GetOrEnforceKnownAlignment(cast<User>(V)->getOperand(0),
7624 } else if (User *GEPI = dyn_castGetElementPtr(V)) {
7625 // If all indexes are zero, it is just the alignment of the base pointer.
7626 bool AllZeroOperands = true;
7627 for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
7628 if (!isa<Constant>(GEPI->getOperand(i)) ||
7629 !cast<Constant>(GEPI->getOperand(i))->isNullValue()) {
7630 AllZeroOperands = false;
7634 if (AllZeroOperands) {
7635 // Treat this like a bitcast.
7636 return GetOrEnforceKnownAlignment(GEPI->getOperand(0), TD, PrefAlign);
7639 unsigned BaseAlignment = GetOrEnforceKnownAlignment(GEPI->getOperand(0),TD);
7640 if (BaseAlignment == 0) return 0;
7642 // Otherwise, if the base alignment is >= the alignment we expect for the
7643 // base pointer type, then we know that the resultant pointer is aligned at
7644 // least as much as its type requires.
7647 const Type *BasePtrTy = GEPI->getOperand(0)->getType();
7648 const PointerType *PtrTy = cast<PointerType>(BasePtrTy);
7649 unsigned Align = TD->getABITypeAlignment(PtrTy->getElementType());
7650 if (Align <= BaseAlignment) {
7651 const Type *GEPTy = GEPI->getType();
7652 const PointerType *GEPPtrTy = cast<PointerType>(GEPTy);
7653 Align = std::min(Align, (unsigned)
7654 TD->getABITypeAlignment(GEPPtrTy->getElementType()));
7663 /// visitCallInst - CallInst simplification. This mostly only handles folding
7664 /// of intrinsic instructions. For normal calls, it allows visitCallSite to do
7665 /// the heavy lifting.
7667 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
7668 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
7669 if (!II) return visitCallSite(&CI);
7671 // Intrinsics cannot occur in an invoke, so handle them here instead of in
7673 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
7674 bool Changed = false;
7676 // memmove/cpy/set of zero bytes is a noop.
7677 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
7678 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
7680 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
7681 if (CI->getZExtValue() == 1) {
7682 // Replace the instruction with just byte operations. We would
7683 // transform other cases to loads/stores, but we don't know if
7684 // alignment is sufficient.
7688 // If we have a memmove and the source operation is a constant global,
7689 // then the source and dest pointers can't alias, so we can change this
7690 // into a call to memcpy.
7691 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(II)) {
7692 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
7693 if (GVSrc->isConstant()) {
7694 Module *M = CI.getParent()->getParent()->getParent();
7696 if (CI.getCalledFunction()->getFunctionType()->getParamType(2) ==
7698 Name = "llvm.memcpy.i32";
7700 Name = "llvm.memcpy.i64";
7701 Constant *MemCpy = M->getOrInsertFunction(Name,
7702 CI.getCalledFunction()->getFunctionType());
7703 CI.setOperand(0, MemCpy);
7708 // If we can determine a pointer alignment that is bigger than currently
7709 // set, update the alignment.
7710 if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) {
7711 unsigned Alignment1 = GetOrEnforceKnownAlignment(MI->getOperand(1), TD);
7712 unsigned Alignment2 = GetOrEnforceKnownAlignment(MI->getOperand(2), TD);
7713 unsigned Align = std::min(Alignment1, Alignment2);
7714 if (MI->getAlignment()->getZExtValue() < Align) {
7715 MI->setAlignment(ConstantInt::get(Type::Int32Ty, Align));
7719 // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
7721 ConstantInt *MemOpLength = dyn_cast<ConstantInt>(CI.getOperand(3));
7723 unsigned Size = MemOpLength->getZExtValue();
7724 unsigned Align = cast<ConstantInt>(CI.getOperand(4))->getZExtValue();
7725 PointerType *NewPtrTy = NULL;
7726 // Destination pointer type is always i8 *
7727 // If Size is 8 then use Int64Ty
7728 // If Size is 4 then use Int32Ty
7729 // If Size is 2 then use Int16Ty
7730 // If Size is 1 then use Int8Ty
7731 if (Size && Size <=8 && !(Size&(Size-1)))
7732 NewPtrTy = PointerType::get(IntegerType::get(Size<<3));
7735 Value *Src = InsertCastBefore(Instruction::BitCast, CI.getOperand(2),
7737 Value *Dest = InsertCastBefore(Instruction::BitCast, CI.getOperand(1),
7739 Value *L = new LoadInst(Src, "tmp", false, Align, &CI);
7740 Value *NS = new StoreInst(L, Dest, false, Align, &CI);
7741 CI.replaceAllUsesWith(NS);
7743 return EraseInstFromFunction(CI);
7746 } else if (isa<MemSetInst>(MI)) {
7747 unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest(), TD);
7748 if (MI->getAlignment()->getZExtValue() < Alignment) {
7749 MI->setAlignment(ConstantInt::get(Type::Int32Ty, Alignment));
7754 if (Changed) return II;
7756 switch (II->getIntrinsicID()) {
7758 case Intrinsic::ppc_altivec_lvx:
7759 case Intrinsic::ppc_altivec_lvxl:
7760 case Intrinsic::x86_sse_loadu_ps:
7761 case Intrinsic::x86_sse2_loadu_pd:
7762 case Intrinsic::x86_sse2_loadu_dq:
7763 // Turn PPC lvx -> load if the pointer is known aligned.
7764 // Turn X86 loadups -> load if the pointer is known aligned.
7765 if (GetOrEnforceKnownAlignment(II->getOperand(1), TD, 16) >= 16) {
7766 Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
7767 PointerType::get(II->getType()), CI);
7768 return new LoadInst(Ptr);
7771 case Intrinsic::ppc_altivec_stvx:
7772 case Intrinsic::ppc_altivec_stvxl:
7773 // Turn stvx -> store if the pointer is known aligned.
7774 if (GetOrEnforceKnownAlignment(II->getOperand(2), TD, 16) >= 16) {
7775 const Type *OpPtrTy = PointerType::get(II->getOperand(1)->getType());
7776 Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(2),
7778 return new StoreInst(II->getOperand(1), Ptr);
7781 case Intrinsic::x86_sse_storeu_ps:
7782 case Intrinsic::x86_sse2_storeu_pd:
7783 case Intrinsic::x86_sse2_storeu_dq:
7784 case Intrinsic::x86_sse2_storel_dq:
7785 // Turn X86 storeu -> store if the pointer is known aligned.
7786 if (GetOrEnforceKnownAlignment(II->getOperand(1), TD, 16) >= 16) {
7787 const Type *OpPtrTy = PointerType::get(II->getOperand(2)->getType());
7788 Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
7790 return new StoreInst(II->getOperand(2), Ptr);
7794 case Intrinsic::x86_sse_cvttss2si: {
7795 // These intrinsics only demands the 0th element of its input vector. If
7796 // we can simplify the input based on that, do so now.
7798 if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), 1,
7800 II->setOperand(1, V);
7806 case Intrinsic::ppc_altivec_vperm:
7807 // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
7808 if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
7809 assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
7811 // Check that all of the elements are integer constants or undefs.
7812 bool AllEltsOk = true;
7813 for (unsigned i = 0; i != 16; ++i) {
7814 if (!isa<ConstantInt>(Mask->getOperand(i)) &&
7815 !isa<UndefValue>(Mask->getOperand(i))) {
7822 // Cast the input vectors to byte vectors.
7823 Value *Op0 = InsertCastBefore(Instruction::BitCast,
7824 II->getOperand(1), Mask->getType(), CI);
7825 Value *Op1 = InsertCastBefore(Instruction::BitCast,
7826 II->getOperand(2), Mask->getType(), CI);
7827 Value *Result = UndefValue::get(Op0->getType());
7829 // Only extract each element once.
7830 Value *ExtractedElts[32];
7831 memset(ExtractedElts, 0, sizeof(ExtractedElts));
7833 for (unsigned i = 0; i != 16; ++i) {
7834 if (isa<UndefValue>(Mask->getOperand(i)))
7836 unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
7837 Idx &= 31; // Match the hardware behavior.
7839 if (ExtractedElts[Idx] == 0) {
7841 new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp");
7842 InsertNewInstBefore(Elt, CI);
7843 ExtractedElts[Idx] = Elt;
7846 // Insert this value into the result vector.
7847 Result = new InsertElementInst(Result, ExtractedElts[Idx], i,"tmp");
7848 InsertNewInstBefore(cast<Instruction>(Result), CI);
7850 return CastInst::create(Instruction::BitCast, Result, CI.getType());
7855 case Intrinsic::stackrestore: {
7856 // If the save is right next to the restore, remove the restore. This can
7857 // happen when variable allocas are DCE'd.
7858 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
7859 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
7860 BasicBlock::iterator BI = SS;
7862 return EraseInstFromFunction(CI);
7866 // If the stack restore is in a return/unwind block and if there are no
7867 // allocas or calls between the restore and the return, nuke the restore.
7868 TerminatorInst *TI = II->getParent()->getTerminator();
7869 if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) {
7870 BasicBlock::iterator BI = II;
7871 bool CannotRemove = false;
7872 for (++BI; &*BI != TI; ++BI) {
7873 if (isa<AllocaInst>(BI) ||
7874 (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) {
7875 CannotRemove = true;
7880 return EraseInstFromFunction(CI);
7887 return visitCallSite(II);
7890 // InvokeInst simplification
7892 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
7893 return visitCallSite(&II);
7896 // visitCallSite - Improvements for call and invoke instructions.
7898 Instruction *InstCombiner::visitCallSite(CallSite CS) {
7899 bool Changed = false;
7901 // If the callee is a constexpr cast of a function, attempt to move the cast
7902 // to the arguments of the call/invoke.
7903 if (transformConstExprCastCall(CS)) return 0;
7905 Value *Callee = CS.getCalledValue();
7907 if (Function *CalleeF = dyn_cast<Function>(Callee))
7908 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
7909 Instruction *OldCall = CS.getInstruction();
7910 // If the call and callee calling conventions don't match, this call must
7911 // be unreachable, as the call is undefined.
7912 new StoreInst(ConstantInt::getTrue(),
7913 UndefValue::get(PointerType::get(Type::Int1Ty)), OldCall);
7914 if (!OldCall->use_empty())
7915 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
7916 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
7917 return EraseInstFromFunction(*OldCall);
7921 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
7922 // This instruction is not reachable, just remove it. We insert a store to
7923 // undef so that we know that this code is not reachable, despite the fact
7924 // that we can't modify the CFG here.
7925 new StoreInst(ConstantInt::getTrue(),
7926 UndefValue::get(PointerType::get(Type::Int1Ty)),
7927 CS.getInstruction());
7929 if (!CS.getInstruction()->use_empty())
7930 CS.getInstruction()->
7931 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
7933 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
7934 // Don't break the CFG, insert a dummy cond branch.
7935 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
7936 ConstantInt::getTrue(), II);
7938 return EraseInstFromFunction(*CS.getInstruction());
7941 if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee))
7942 if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0)))
7943 if (In->getIntrinsicID() == Intrinsic::init_trampoline)
7944 return transformCallThroughTrampoline(CS);
7946 const PointerType *PTy = cast<PointerType>(Callee->getType());
7947 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
7948 if (FTy->isVarArg()) {
7949 // See if we can optimize any arguments passed through the varargs area of
7951 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
7952 E = CS.arg_end(); I != E; ++I)
7953 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
7954 // If this cast does not effect the value passed through the varargs
7955 // area, we can eliminate the use of the cast.
7956 Value *Op = CI->getOperand(0);
7957 if (CI->isLosslessCast()) {
7964 return Changed ? CS.getInstruction() : 0;
7967 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
7968 // attempt to move the cast to the arguments of the call/invoke.
7970 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
7971 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
7972 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
7973 if (CE->getOpcode() != Instruction::BitCast ||
7974 !isa<Function>(CE->getOperand(0)))
7976 Function *Callee = cast<Function>(CE->getOperand(0));
7977 Instruction *Caller = CS.getInstruction();
7979 // Okay, this is a cast from a function to a different type. Unless doing so
7980 // would cause a type conversion of one of our arguments, change this call to
7981 // be a direct call with arguments casted to the appropriate types.
7983 const FunctionType *FT = Callee->getFunctionType();
7984 const Type *OldRetTy = Caller->getType();
7986 const FunctionType *ActualFT =
7987 cast<FunctionType>(cast<PointerType>(CE->getType())->getElementType());
7989 // If the parameter attributes don't match up, don't do the xform. We don't
7990 // want to lose an sret attribute or something.
7991 if (FT->getParamAttrs() != ActualFT->getParamAttrs())
7994 // Check to see if we are changing the return type...
7995 if (OldRetTy != FT->getReturnType()) {
7996 if (Callee->isDeclaration() && !Caller->use_empty() &&
7997 // Conversion is ok if changing from pointer to int of same size.
7998 !(isa<PointerType>(FT->getReturnType()) &&
7999 TD->getIntPtrType() == OldRetTy))
8000 return false; // Cannot transform this return value.
8002 // If the callsite is an invoke instruction, and the return value is used by
8003 // a PHI node in a successor, we cannot change the return type of the call
8004 // because there is no place to put the cast instruction (without breaking
8005 // the critical edge). Bail out in this case.
8006 if (!Caller->use_empty())
8007 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
8008 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
8010 if (PHINode *PN = dyn_cast<PHINode>(*UI))
8011 if (PN->getParent() == II->getNormalDest() ||
8012 PN->getParent() == II->getUnwindDest())
8016 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
8017 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
8019 CallSite::arg_iterator AI = CS.arg_begin();
8020 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
8021 const Type *ParamTy = FT->getParamType(i);
8022 const Type *ActTy = (*AI)->getType();
8023 ConstantInt *c = dyn_cast<ConstantInt>(*AI);
8024 //Some conversions are safe even if we do not have a body.
8025 //Either we can cast directly, or we can upconvert the argument
8026 bool isConvertible = ActTy == ParamTy ||
8027 (isa<PointerType>(ParamTy) && isa<PointerType>(ActTy)) ||
8028 (ParamTy->isInteger() && ActTy->isInteger() &&
8029 ParamTy->getPrimitiveSizeInBits() >= ActTy->getPrimitiveSizeInBits()) ||
8030 (c && ParamTy->getPrimitiveSizeInBits() >= ActTy->getPrimitiveSizeInBits()
8031 && c->getValue().isStrictlyPositive());
8032 if (Callee->isDeclaration() && !isConvertible) return false;
8034 // Most other conversions can be done if we have a body, even if these
8035 // lose information, e.g. int->short.
8036 // Some conversions cannot be done at all, e.g. float to pointer.
8037 // Logic here parallels CastInst::getCastOpcode (the design there
8038 // requires legality checks like this be done before calling it).
8039 if (ParamTy->isInteger()) {
8040 if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
8041 if (VActTy->getBitWidth() != ParamTy->getPrimitiveSizeInBits())
8044 if (!ActTy->isInteger() && !ActTy->isFloatingPoint() &&
8045 !isa<PointerType>(ActTy))
8047 } else if (ParamTy->isFloatingPoint()) {
8048 if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
8049 if (VActTy->getBitWidth() != ParamTy->getPrimitiveSizeInBits())
8052 if (!ActTy->isInteger() && !ActTy->isFloatingPoint())
8054 } else if (const VectorType *VParamTy = dyn_cast<VectorType>(ParamTy)) {
8055 if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
8056 if (VActTy->getBitWidth() != VParamTy->getBitWidth())
8059 if (VParamTy->getBitWidth() != ActTy->getPrimitiveSizeInBits())
8061 } else if (isa<PointerType>(ParamTy)) {
8062 if (!ActTy->isInteger() && !isa<PointerType>(ActTy))
8069 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
8070 Callee->isDeclaration())
8071 return false; // Do not delete arguments unless we have a function body...
8073 // Okay, we decided that this is a safe thing to do: go ahead and start
8074 // inserting cast instructions as necessary...
8075 std::vector<Value*> Args;
8076 Args.reserve(NumActualArgs);
8078 AI = CS.arg_begin();
8079 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
8080 const Type *ParamTy = FT->getParamType(i);
8081 if ((*AI)->getType() == ParamTy) {
8082 Args.push_back(*AI);
8084 Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
8085 false, ParamTy, false);
8086 CastInst *NewCast = CastInst::create(opcode, *AI, ParamTy, "tmp");
8087 Args.push_back(InsertNewInstBefore(NewCast, *Caller));
8091 // If the function takes more arguments than the call was taking, add them
8093 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
8094 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
8096 // If we are removing arguments to the function, emit an obnoxious warning...
8097 if (FT->getNumParams() < NumActualArgs)
8098 if (!FT->isVarArg()) {
8099 cerr << "WARNING: While resolving call to function '"
8100 << Callee->getName() << "' arguments were dropped!\n";
8102 // Add all of the arguments in their promoted form to the arg list...
8103 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
8104 const Type *PTy = getPromotedType((*AI)->getType());
8105 if (PTy != (*AI)->getType()) {
8106 // Must promote to pass through va_arg area!
8107 Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, false,
8109 Instruction *Cast = CastInst::create(opcode, *AI, PTy, "tmp");
8110 InsertNewInstBefore(Cast, *Caller);
8111 Args.push_back(Cast);
8113 Args.push_back(*AI);
8118 if (FT->getReturnType() == Type::VoidTy)
8119 Caller->setName(""); // Void type should not have a name.
8122 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
8123 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
8124 Args.begin(), Args.end(), Caller->getName(), Caller);
8125 cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
8127 NC = new CallInst(Callee, Args.begin(), Args.end(),
8128 Caller->getName(), Caller);
8129 if (cast<CallInst>(Caller)->isTailCall())
8130 cast<CallInst>(NC)->setTailCall();
8131 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
8134 // Insert a cast of the return type as necessary.
8136 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
8137 if (NV->getType() != Type::VoidTy) {
8138 const Type *CallerTy = Caller->getType();
8139 Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
8141 NV = NC = CastInst::create(opcode, NC, CallerTy, "tmp");
8143 // If this is an invoke instruction, we should insert it after the first
8144 // non-phi, instruction in the normal successor block.
8145 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
8146 BasicBlock::iterator I = II->getNormalDest()->begin();
8147 while (isa<PHINode>(I)) ++I;
8148 InsertNewInstBefore(NC, *I);
8150 // Otherwise, it's a call, just insert cast right after the call instr
8151 InsertNewInstBefore(NC, *Caller);
8153 AddUsersToWorkList(*Caller);
8155 NV = UndefValue::get(Caller->getType());
8159 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
8160 Caller->replaceAllUsesWith(NV);
8161 Caller->eraseFromParent();
8162 RemoveFromWorkList(Caller);
8166 // transformCallThroughTrampoline - Turn a call to a function created by the
8167 // init_trampoline intrinsic into a direct call to the underlying function.
8169 Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) {
8170 Value *Callee = CS.getCalledValue();
8171 const PointerType *PTy = cast<PointerType>(Callee->getType());
8172 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
8174 IntrinsicInst *Tramp =
8175 cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0));
8178 cast<Function>(IntrinsicInst::StripPointerCasts(Tramp->getOperand(2)));
8179 const PointerType *NestFPTy = cast<PointerType>(NestF->getType());
8180 const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
8182 if (const ParamAttrsList *NestAttrs = NestFTy->getParamAttrs()) {
8183 unsigned NestIdx = 1;
8184 const Type *NestTy = 0;
8185 uint16_t NestAttr = 0;
8187 // Look for a parameter marked with the 'nest' attribute.
8188 for (FunctionType::param_iterator I = NestFTy->param_begin(),
8189 E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
8190 if (NestAttrs->paramHasAttr(NestIdx, ParamAttr::Nest)) {
8191 // Record the parameter type and any other attributes.
8193 NestAttr = NestAttrs->getParamAttrs(NestIdx);
8198 Instruction *Caller = CS.getInstruction();
8199 std::vector<Value*> NewArgs;
8200 NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
8202 // Insert the nest argument into the call argument list, which may
8203 // mean appending it.
8206 CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
8208 if (Idx == NestIdx) {
8209 // Add the chain argument.
8210 Value *NestVal = Tramp->getOperand(3);
8211 if (NestVal->getType() != NestTy)
8212 NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller);
8213 NewArgs.push_back(NestVal);
8219 // Add the original argument.
8220 NewArgs.push_back(*I);
8226 // The trampoline may have been bitcast to a bogus type (FTy).
8227 // Handle this by synthesizing a new function type, equal to FTy
8228 // with the chain parameter inserted. Likewise for attributes.
8230 const ParamAttrsList *Attrs = FTy->getParamAttrs();
8231 std::vector<const Type*> NewTypes;
8232 ParamAttrsVector NewAttrs;
8233 NewTypes.reserve(FTy->getNumParams()+1);
8235 // Add any function result attributes.
8236 uint16_t Attr = Attrs ? Attrs->getParamAttrs(0) : 0;
8238 NewAttrs.push_back (ParamAttrsWithIndex::get(0, Attr));
8240 // Insert the chain's type into the list of parameter types, which may
8241 // mean appending it. Likewise for the chain's attributes.
8244 FunctionType::param_iterator I = FTy->param_begin(),
8245 E = FTy->param_end();
8248 if (Idx == NestIdx) {
8249 // Add the chain's type and attributes.
8250 NewTypes.push_back(NestTy);
8251 NewAttrs.push_back(ParamAttrsWithIndex::get(NestIdx, NestAttr));
8257 // Add the original type and attributes.
8258 NewTypes.push_back(*I);
8259 Attr = Attrs ? Attrs->getParamAttrs(Idx) : 0;
8262 (ParamAttrsWithIndex::get(Idx + (Idx >= NestIdx), Attr));
8268 // Replace the trampoline call with a direct call. Let the generic
8269 // code sort out any function type mismatches.
8270 FunctionType *NewFTy =
8271 FunctionType::get(FTy->getReturnType(), NewTypes, FTy->isVarArg(),
8272 ParamAttrsList::get(NewAttrs));
8273 Constant *NewCallee = NestF->getType() == PointerType::get(NewFTy) ?
8274 NestF : ConstantExpr::getBitCast(NestF, PointerType::get(NewFTy));
8276 Instruction *NewCaller;
8277 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
8278 NewCaller = new InvokeInst(NewCallee,
8279 II->getNormalDest(), II->getUnwindDest(),
8280 NewArgs.begin(), NewArgs.end(),
8281 Caller->getName(), Caller);
8282 cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
8284 NewCaller = new CallInst(NewCallee, NewArgs.begin(), NewArgs.end(),
8285 Caller->getName(), Caller);
8286 if (cast<CallInst>(Caller)->isTailCall())
8287 cast<CallInst>(NewCaller)->setTailCall();
8288 cast<CallInst>(NewCaller)->
8289 setCallingConv(cast<CallInst>(Caller)->getCallingConv());
8291 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
8292 Caller->replaceAllUsesWith(NewCaller);
8293 Caller->eraseFromParent();
8294 RemoveFromWorkList(Caller);
8299 // Replace the trampoline call with a direct call. Since there is no 'nest'
8300 // parameter, there is no need to adjust the argument list. Let the generic
8301 // code sort out any function type mismatches.
8302 Constant *NewCallee =
8303 NestF->getType() == PTy ? NestF : ConstantExpr::getBitCast(NestF, PTy);
8304 CS.setCalledFunction(NewCallee);
8305 return CS.getInstruction();
8308 /// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(c,d)]
8309 /// and if a/b/c/d and the add's all have a single use, turn this into two phi's
8310 /// and a single binop.
8311 Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
8312 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
8313 assert(isa<BinaryOperator>(FirstInst) || isa<GetElementPtrInst>(FirstInst) ||
8314 isa<CmpInst>(FirstInst));
8315 unsigned Opc = FirstInst->getOpcode();
8316 Value *LHSVal = FirstInst->getOperand(0);
8317 Value *RHSVal = FirstInst->getOperand(1);
8319 const Type *LHSType = LHSVal->getType();
8320 const Type *RHSType = RHSVal->getType();
8322 // Scan to see if all operands are the same opcode, all have one use, and all
8323 // kill their operands (i.e. the operands have one use).
8324 for (unsigned i = 0; i != PN.getNumIncomingValues(); ++i) {
8325 Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
8326 if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
8327 // Verify type of the LHS matches so we don't fold cmp's of different
8328 // types or GEP's with different index types.
8329 I->getOperand(0)->getType() != LHSType ||
8330 I->getOperand(1)->getType() != RHSType)
8333 // If they are CmpInst instructions, check their predicates
8334 if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
8335 if (cast<CmpInst>(I)->getPredicate() !=
8336 cast<CmpInst>(FirstInst)->getPredicate())
8339 // Keep track of which operand needs a phi node.
8340 if (I->getOperand(0) != LHSVal) LHSVal = 0;
8341 if (I->getOperand(1) != RHSVal) RHSVal = 0;
8344 // Otherwise, this is safe to transform, determine if it is profitable.
8346 // If this is a GEP, and if the index (not the pointer) needs a PHI, bail out.
8347 // Indexes are often folded into load/store instructions, so we don't want to
8348 // hide them behind a phi.
8349 if (isa<GetElementPtrInst>(FirstInst) && RHSVal == 0)
8352 Value *InLHS = FirstInst->getOperand(0);
8353 Value *InRHS = FirstInst->getOperand(1);
8354 PHINode *NewLHS = 0, *NewRHS = 0;
8356 NewLHS = new PHINode(LHSType, FirstInst->getOperand(0)->getName()+".pn");
8357 NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
8358 NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
8359 InsertNewInstBefore(NewLHS, PN);
8364 NewRHS = new PHINode(RHSType, FirstInst->getOperand(1)->getName()+".pn");
8365 NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
8366 NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
8367 InsertNewInstBefore(NewRHS, PN);
8371 // Add all operands to the new PHIs.
8372 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8374 Value *NewInLHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
8375 NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
8378 Value *NewInRHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(1);
8379 NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
8383 if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
8384 return BinaryOperator::create(BinOp->getOpcode(), LHSVal, RHSVal);
8385 else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
8386 return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(), LHSVal,
8389 assert(isa<GetElementPtrInst>(FirstInst));
8390 return new GetElementPtrInst(LHSVal, RHSVal);
8394 /// isSafeToSinkLoad - Return true if we know that it is safe sink the load out
8395 /// of the block that defines it. This means that it must be obvious the value
8396 /// of the load is not changed from the point of the load to the end of the
8399 /// Finally, it is safe, but not profitable, to sink a load targetting a
8400 /// non-address-taken alloca. Doing so will cause us to not promote the alloca
8402 static bool isSafeToSinkLoad(LoadInst *L) {
8403 BasicBlock::iterator BBI = L, E = L->getParent()->end();
8405 for (++BBI; BBI != E; ++BBI)
8406 if (BBI->mayWriteToMemory())
8409 // Check for non-address taken alloca. If not address-taken already, it isn't
8410 // profitable to do this xform.
8411 if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
8412 bool isAddressTaken = false;
8413 for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
8415 if (isa<LoadInst>(UI)) continue;
8416 if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
8417 // If storing TO the alloca, then the address isn't taken.
8418 if (SI->getOperand(1) == AI) continue;
8420 isAddressTaken = true;
8424 if (!isAddressTaken)
8432 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
8433 // operator and they all are only used by the PHI, PHI together their
8434 // inputs, and do the operation once, to the result of the PHI.
8435 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
8436 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
8438 // Scan the instruction, looking for input operations that can be folded away.
8439 // If all input operands to the phi are the same instruction (e.g. a cast from
8440 // the same type or "+42") we can pull the operation through the PHI, reducing
8441 // code size and simplifying code.
8442 Constant *ConstantOp = 0;
8443 const Type *CastSrcTy = 0;
8444 bool isVolatile = false;
8445 if (isa<CastInst>(FirstInst)) {
8446 CastSrcTy = FirstInst->getOperand(0)->getType();
8447 } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
8448 // Can fold binop, compare or shift here if the RHS is a constant,
8449 // otherwise call FoldPHIArgBinOpIntoPHI.
8450 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
8451 if (ConstantOp == 0)
8452 return FoldPHIArgBinOpIntoPHI(PN);
8453 } else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) {
8454 isVolatile = LI->isVolatile();
8455 // We can't sink the load if the loaded value could be modified between the
8456 // load and the PHI.
8457 if (LI->getParent() != PN.getIncomingBlock(0) ||
8458 !isSafeToSinkLoad(LI))
8460 } else if (isa<GetElementPtrInst>(FirstInst)) {
8461 if (FirstInst->getNumOperands() == 2)
8462 return FoldPHIArgBinOpIntoPHI(PN);
8463 // Can't handle general GEPs yet.
8466 return 0; // Cannot fold this operation.
8469 // Check to see if all arguments are the same operation.
8470 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8471 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
8472 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
8473 if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst))
8476 if (I->getOperand(0)->getType() != CastSrcTy)
8477 return 0; // Cast operation must match.
8478 } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
8479 // We can't sink the load if the loaded value could be modified between
8480 // the load and the PHI.
8481 if (LI->isVolatile() != isVolatile ||
8482 LI->getParent() != PN.getIncomingBlock(i) ||
8483 !isSafeToSinkLoad(LI))
8485 } else if (I->getOperand(1) != ConstantOp) {
8490 // Okay, they are all the same operation. Create a new PHI node of the
8491 // correct type, and PHI together all of the LHS's of the instructions.
8492 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
8493 PN.getName()+".in");
8494 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
8496 Value *InVal = FirstInst->getOperand(0);
8497 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
8499 // Add all operands to the new PHI.
8500 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
8501 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
8502 if (NewInVal != InVal)
8504 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
8509 // The new PHI unions all of the same values together. This is really
8510 // common, so we handle it intelligently here for compile-time speed.
8514 InsertNewInstBefore(NewPN, PN);
8518 // Insert and return the new operation.
8519 if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
8520 return CastInst::create(FirstCI->getOpcode(), PhiVal, PN.getType());
8521 else if (isa<LoadInst>(FirstInst))
8522 return new LoadInst(PhiVal, "", isVolatile);
8523 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
8524 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
8525 else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
8526 return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(),
8527 PhiVal, ConstantOp);
8529 assert(0 && "Unknown operation");
8533 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
8535 static bool DeadPHICycle(PHINode *PN,
8536 SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
8537 if (PN->use_empty()) return true;
8538 if (!PN->hasOneUse()) return false;
8540 // Remember this node, and if we find the cycle, return.
8541 if (!PotentiallyDeadPHIs.insert(PN))
8544 // Don't scan crazily complex things.
8545 if (PotentiallyDeadPHIs.size() == 16)
8548 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
8549 return DeadPHICycle(PU, PotentiallyDeadPHIs);
8554 /// PHIsEqualValue - Return true if this phi node is always equal to
8555 /// NonPhiInVal. This happens with mutually cyclic phi nodes like:
8556 /// z = some value; x = phi (y, z); y = phi (x, z)
8557 static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
8558 SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
8559 // See if we already saw this PHI node.
8560 if (!ValueEqualPHIs.insert(PN))
8563 // Don't scan crazily complex things.
8564 if (ValueEqualPHIs.size() == 16)
8567 // Scan the operands to see if they are either phi nodes or are equal to
8569 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
8570 Value *Op = PN->getIncomingValue(i);
8571 if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
8572 if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
8574 } else if (Op != NonPhiInVal)
8582 // PHINode simplification
8584 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
8585 // If LCSSA is around, don't mess with Phi nodes
8586 if (MustPreserveLCSSA) return 0;
8588 if (Value *V = PN.hasConstantValue())
8589 return ReplaceInstUsesWith(PN, V);
8591 // If all PHI operands are the same operation, pull them through the PHI,
8592 // reducing code size.
8593 if (isa<Instruction>(PN.getIncomingValue(0)) &&
8594 PN.getIncomingValue(0)->hasOneUse())
8595 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
8598 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
8599 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
8600 // PHI)... break the cycle.
8601 if (PN.hasOneUse()) {
8602 Instruction *PHIUser = cast<Instruction>(PN.use_back());
8603 if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
8604 SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
8605 PotentiallyDeadPHIs.insert(&PN);
8606 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
8607 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
8610 // If this phi has a single use, and if that use just computes a value for
8611 // the next iteration of a loop, delete the phi. This occurs with unused
8612 // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
8613 // common case here is good because the only other things that catch this
8614 // are induction variable analysis (sometimes) and ADCE, which is only run
8616 if (PHIUser->hasOneUse() &&
8617 (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
8618 PHIUser->use_back() == &PN) {
8619 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
8623 // We sometimes end up with phi cycles that non-obviously end up being the
8624 // same value, for example:
8625 // z = some value; x = phi (y, z); y = phi (x, z)
8626 // where the phi nodes don't necessarily need to be in the same block. Do a
8627 // quick check to see if the PHI node only contains a single non-phi value, if
8628 // so, scan to see if the phi cycle is actually equal to that value.
8630 unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues();
8631 // Scan for the first non-phi operand.
8632 while (InValNo != NumOperandVals &&
8633 isa<PHINode>(PN.getIncomingValue(InValNo)))
8636 if (InValNo != NumOperandVals) {
8637 Value *NonPhiInVal = PN.getOperand(InValNo);
8639 // Scan the rest of the operands to see if there are any conflicts, if so
8640 // there is no need to recursively scan other phis.
8641 for (++InValNo; InValNo != NumOperandVals; ++InValNo) {
8642 Value *OpVal = PN.getIncomingValue(InValNo);
8643 if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
8647 // If we scanned over all operands, then we have one unique value plus
8648 // phi values. Scan PHI nodes to see if they all merge in each other or
8650 if (InValNo == NumOperandVals) {
8651 SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
8652 if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
8653 return ReplaceInstUsesWith(PN, NonPhiInVal);
8660 static Value *InsertCastToIntPtrTy(Value *V, const Type *DTy,
8661 Instruction *InsertPoint,
8663 unsigned PtrSize = DTy->getPrimitiveSizeInBits();
8664 unsigned VTySize = V->getType()->getPrimitiveSizeInBits();
8665 // We must cast correctly to the pointer type. Ensure that we
8666 // sign extend the integer value if it is smaller as this is
8667 // used for address computation.
8668 Instruction::CastOps opcode =
8669 (VTySize < PtrSize ? Instruction::SExt :
8670 (VTySize == PtrSize ? Instruction::BitCast : Instruction::Trunc));
8671 return IC->InsertCastBefore(opcode, V, DTy, *InsertPoint);
8675 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
8676 Value *PtrOp = GEP.getOperand(0);
8677 // Is it 'getelementptr %P, i32 0' or 'getelementptr %P'
8678 // If so, eliminate the noop.
8679 if (GEP.getNumOperands() == 1)
8680 return ReplaceInstUsesWith(GEP, PtrOp);
8682 if (isa<UndefValue>(GEP.getOperand(0)))
8683 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
8685 bool HasZeroPointerIndex = false;
8686 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
8687 HasZeroPointerIndex = C->isNullValue();
8689 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
8690 return ReplaceInstUsesWith(GEP, PtrOp);
8692 // Eliminate unneeded casts for indices.
8693 bool MadeChange = false;
8695 gep_type_iterator GTI = gep_type_begin(GEP);
8696 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI) {
8697 if (isa<SequentialType>(*GTI)) {
8698 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
8699 if (CI->getOpcode() == Instruction::ZExt ||
8700 CI->getOpcode() == Instruction::SExt) {
8701 const Type *SrcTy = CI->getOperand(0)->getType();
8702 // We can eliminate a cast from i32 to i64 iff the target
8703 // is a 32-bit pointer target.
8704 if (SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
8706 GEP.setOperand(i, CI->getOperand(0));
8710 // If we are using a wider index than needed for this platform, shrink it
8711 // to what we need. If the incoming value needs a cast instruction,
8712 // insert it. This explicit cast can make subsequent optimizations more
8714 Value *Op = GEP.getOperand(i);
8715 if (TD->getTypeSizeInBits(Op->getType()) > TD->getPointerSizeInBits())
8716 if (Constant *C = dyn_cast<Constant>(Op)) {
8717 GEP.setOperand(i, ConstantExpr::getTrunc(C, TD->getIntPtrType()));
8720 Op = InsertCastBefore(Instruction::Trunc, Op, TD->getIntPtrType(),
8722 GEP.setOperand(i, Op);
8727 if (MadeChange) return &GEP;
8729 // If this GEP instruction doesn't move the pointer, and if the input operand
8730 // is a bitcast of another pointer, just replace the GEP with a bitcast of the
8731 // real input to the dest type.
8732 if (GEP.hasAllZeroIndices()) {
8733 if (BitCastInst *BCI = dyn_cast<BitCastInst>(GEP.getOperand(0))) {
8734 // If the bitcast is of an allocation, and the allocation will be
8735 // converted to match the type of the cast, don't touch this.
8736 if (isa<AllocationInst>(BCI->getOperand(0))) {
8737 // See if the bitcast simplifies, if so, don't nuke this GEP yet.
8738 if (Instruction *I = visitBitCast(*BCI)) {
8741 BCI->getParent()->getInstList().insert(BCI, I);
8742 ReplaceInstUsesWith(*BCI, I);
8747 return new BitCastInst(BCI->getOperand(0), GEP.getType());
8751 // Combine Indices - If the source pointer to this getelementptr instruction
8752 // is a getelementptr instruction, combine the indices of the two
8753 // getelementptr instructions into a single instruction.
8755 SmallVector<Value*, 8> SrcGEPOperands;
8756 if (User *Src = dyn_castGetElementPtr(PtrOp))
8757 SrcGEPOperands.append(Src->op_begin(), Src->op_end());
8759 if (!SrcGEPOperands.empty()) {
8760 // Note that if our source is a gep chain itself that we wait for that
8761 // chain to be resolved before we perform this transformation. This
8762 // avoids us creating a TON of code in some cases.
8764 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
8765 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
8766 return 0; // Wait until our source is folded to completion.
8768 SmallVector<Value*, 8> Indices;
8770 // Find out whether the last index in the source GEP is a sequential idx.
8771 bool EndsWithSequential = false;
8772 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
8773 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
8774 EndsWithSequential = !isa<StructType>(*I);
8776 // Can we combine the two pointer arithmetics offsets?
8777 if (EndsWithSequential) {
8778 // Replace: gep (gep %P, long B), long A, ...
8779 // With: T = long A+B; gep %P, T, ...
8781 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
8782 if (SO1 == Constant::getNullValue(SO1->getType())) {
8784 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
8787 // If they aren't the same type, convert both to an integer of the
8788 // target's pointer size.
8789 if (SO1->getType() != GO1->getType()) {
8790 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
8791 SO1 = ConstantExpr::getIntegerCast(SO1C, GO1->getType(), true);
8792 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
8793 GO1 = ConstantExpr::getIntegerCast(GO1C, SO1->getType(), true);
8795 unsigned PS = TD->getPointerSizeInBits();
8796 if (TD->getTypeSizeInBits(SO1->getType()) == PS) {
8797 // Convert GO1 to SO1's type.
8798 GO1 = InsertCastToIntPtrTy(GO1, SO1->getType(), &GEP, this);
8800 } else if (TD->getTypeSizeInBits(GO1->getType()) == PS) {
8801 // Convert SO1 to GO1's type.
8802 SO1 = InsertCastToIntPtrTy(SO1, GO1->getType(), &GEP, this);
8804 const Type *PT = TD->getIntPtrType();
8805 SO1 = InsertCastToIntPtrTy(SO1, PT, &GEP, this);
8806 GO1 = InsertCastToIntPtrTy(GO1, PT, &GEP, this);
8810 if (isa<Constant>(SO1) && isa<Constant>(GO1))
8811 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
8813 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
8814 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
8818 // Recycle the GEP we already have if possible.
8819 if (SrcGEPOperands.size() == 2) {
8820 GEP.setOperand(0, SrcGEPOperands[0]);
8821 GEP.setOperand(1, Sum);
8824 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
8825 SrcGEPOperands.end()-1);
8826 Indices.push_back(Sum);
8827 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
8829 } else if (isa<Constant>(*GEP.idx_begin()) &&
8830 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
8831 SrcGEPOperands.size() != 1) {
8832 // Otherwise we can do the fold if the first index of the GEP is a zero
8833 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
8834 SrcGEPOperands.end());
8835 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
8838 if (!Indices.empty())
8839 return new GetElementPtrInst(SrcGEPOperands[0], Indices.begin(),
8840 Indices.end(), GEP.getName());
8842 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
8843 // GEP of global variable. If all of the indices for this GEP are
8844 // constants, we can promote this to a constexpr instead of an instruction.
8846 // Scan for nonconstants...
8847 SmallVector<Constant*, 8> Indices;
8848 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
8849 for (; I != E && isa<Constant>(*I); ++I)
8850 Indices.push_back(cast<Constant>(*I));
8852 if (I == E) { // If they are all constants...
8853 Constant *CE = ConstantExpr::getGetElementPtr(GV,
8854 &Indices[0],Indices.size());
8856 // Replace all uses of the GEP with the new constexpr...
8857 return ReplaceInstUsesWith(GEP, CE);
8859 } else if (Value *X = getBitCastOperand(PtrOp)) { // Is the operand a cast?
8860 if (!isa<PointerType>(X->getType())) {
8861 // Not interesting. Source pointer must be a cast from pointer.
8862 } else if (HasZeroPointerIndex) {
8863 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
8864 // into : GEP [10 x ubyte]* X, long 0, ...
8866 // This occurs when the program declares an array extern like "int X[];"
8868 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
8869 const PointerType *XTy = cast<PointerType>(X->getType());
8870 if (const ArrayType *XATy =
8871 dyn_cast<ArrayType>(XTy->getElementType()))
8872 if (const ArrayType *CATy =
8873 dyn_cast<ArrayType>(CPTy->getElementType()))
8874 if (CATy->getElementType() == XATy->getElementType()) {
8875 // At this point, we know that the cast source type is a pointer
8876 // to an array of the same type as the destination pointer
8877 // array. Because the array type is never stepped over (there
8878 // is a leading zero) we can fold the cast into this GEP.
8879 GEP.setOperand(0, X);
8882 } else if (GEP.getNumOperands() == 2) {
8883 // Transform things like:
8884 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
8885 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
8886 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
8887 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
8888 if (isa<ArrayType>(SrcElTy) &&
8889 TD->getABITypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
8890 TD->getABITypeSize(ResElTy)) {
8892 Idx[0] = Constant::getNullValue(Type::Int32Ty);
8893 Idx[1] = GEP.getOperand(1);
8894 Value *V = InsertNewInstBefore(
8895 new GetElementPtrInst(X, Idx, Idx + 2, GEP.getName()), GEP);
8896 // V and GEP are both pointer types --> BitCast
8897 return new BitCastInst(V, GEP.getType());
8900 // Transform things like:
8901 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
8902 // (where tmp = 8*tmp2) into:
8903 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
8905 if (isa<ArrayType>(SrcElTy) &&
8906 (ResElTy == Type::Int8Ty || ResElTy == Type::Int8Ty)) {
8907 uint64_t ArrayEltSize =
8908 TD->getABITypeSize(cast<ArrayType>(SrcElTy)->getElementType());
8910 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
8911 // allow either a mul, shift, or constant here.
8913 ConstantInt *Scale = 0;
8914 if (ArrayEltSize == 1) {
8915 NewIdx = GEP.getOperand(1);
8916 Scale = ConstantInt::get(NewIdx->getType(), 1);
8917 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
8918 NewIdx = ConstantInt::get(CI->getType(), 1);
8920 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
8921 if (Inst->getOpcode() == Instruction::Shl &&
8922 isa<ConstantInt>(Inst->getOperand(1))) {
8923 ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
8924 uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
8925 Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmtVal);
8926 NewIdx = Inst->getOperand(0);
8927 } else if (Inst->getOpcode() == Instruction::Mul &&
8928 isa<ConstantInt>(Inst->getOperand(1))) {
8929 Scale = cast<ConstantInt>(Inst->getOperand(1));
8930 NewIdx = Inst->getOperand(0);
8934 // If the index will be to exactly the right offset with the scale taken
8935 // out, perform the transformation.
8936 if (Scale && Scale->getZExtValue() % ArrayEltSize == 0) {
8937 if (isa<ConstantInt>(Scale))
8938 Scale = ConstantInt::get(Scale->getType(),
8939 Scale->getZExtValue() / ArrayEltSize);
8940 if (Scale->getZExtValue() != 1) {
8941 Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
8943 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
8944 NewIdx = InsertNewInstBefore(Sc, GEP);
8947 // Insert the new GEP instruction.
8949 Idx[0] = Constant::getNullValue(Type::Int32Ty);
8951 Instruction *NewGEP =
8952 new GetElementPtrInst(X, Idx, Idx + 2, GEP.getName());
8953 NewGEP = InsertNewInstBefore(NewGEP, GEP);
8954 // The NewGEP must be pointer typed, so must the old one -> BitCast
8955 return new BitCastInst(NewGEP, GEP.getType());
8964 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
8965 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
8966 if (AI.isArrayAllocation()) // Check C != 1
8967 if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
8969 ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
8970 AllocationInst *New = 0;
8972 // Create and insert the replacement instruction...
8973 if (isa<MallocInst>(AI))
8974 New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
8976 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
8977 New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
8980 InsertNewInstBefore(New, AI);
8982 // Scan to the end of the allocation instructions, to skip over a block of
8983 // allocas if possible...
8985 BasicBlock::iterator It = New;
8986 while (isa<AllocationInst>(*It)) ++It;
8988 // Now that I is pointing to the first non-allocation-inst in the block,
8989 // insert our getelementptr instruction...
8991 Value *NullIdx = Constant::getNullValue(Type::Int32Ty);
8995 Value *V = new GetElementPtrInst(New, Idx, Idx + 2,
8996 New->getName()+".sub", It);
8998 // Now make everything use the getelementptr instead of the original
9000 return ReplaceInstUsesWith(AI, V);
9001 } else if (isa<UndefValue>(AI.getArraySize())) {
9002 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
9005 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
9006 // Note that we only do this for alloca's, because malloc should allocate and
9007 // return a unique pointer, even for a zero byte allocation.
9008 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
9009 TD->getABITypeSize(AI.getAllocatedType()) == 0)
9010 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
9015 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
9016 Value *Op = FI.getOperand(0);
9018 // free undef -> unreachable.
9019 if (isa<UndefValue>(Op)) {
9020 // Insert a new store to null because we cannot modify the CFG here.
9021 new StoreInst(ConstantInt::getTrue(),
9022 UndefValue::get(PointerType::get(Type::Int1Ty)), &FI);
9023 return EraseInstFromFunction(FI);
9026 // If we have 'free null' delete the instruction. This can happen in stl code
9027 // when lots of inlining happens.
9028 if (isa<ConstantPointerNull>(Op))
9029 return EraseInstFromFunction(FI);
9031 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
9032 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op)) {
9033 FI.setOperand(0, CI->getOperand(0));
9037 // Change free (gep X, 0,0,0,0) into free(X)
9038 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
9039 if (GEPI->hasAllZeroIndices()) {
9040 AddToWorkList(GEPI);
9041 FI.setOperand(0, GEPI->getOperand(0));
9046 // Change free(malloc) into nothing, if the malloc has a single use.
9047 if (MallocInst *MI = dyn_cast<MallocInst>(Op))
9048 if (MI->hasOneUse()) {
9049 EraseInstFromFunction(FI);
9050 return EraseInstFromFunction(*MI);
9057 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
9058 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
9059 const TargetData *TD) {
9060 User *CI = cast<User>(LI.getOperand(0));
9061 Value *CastOp = CI->getOperand(0);
9063 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(CI)) {
9064 // Instead of loading constant c string, use corresponding integer value
9065 // directly if string length is small enough.
9066 const std::string &Str = CE->getOperand(0)->getStringValue();
9068 unsigned len = Str.length();
9069 const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
9070 unsigned numBits = Ty->getPrimitiveSizeInBits();
9071 // Replace LI with immediate integer store.
9072 if ((numBits >> 3) == len + 1) {
9073 APInt StrVal(numBits, 0);
9074 APInt SingleChar(numBits, 0);
9075 if (TD->isLittleEndian()) {
9076 for (signed i = len-1; i >= 0; i--) {
9077 SingleChar = (uint64_t) Str[i];
9078 StrVal = (StrVal << 8) | SingleChar;
9081 for (unsigned i = 0; i < len; i++) {
9082 SingleChar = (uint64_t) Str[i];
9083 StrVal = (StrVal << 8) | SingleChar;
9085 // Append NULL at the end.
9087 StrVal = (StrVal << 8) | SingleChar;
9089 Value *NL = ConstantInt::get(StrVal);
9090 return IC.ReplaceInstUsesWith(LI, NL);
9095 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
9096 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
9097 const Type *SrcPTy = SrcTy->getElementType();
9099 if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
9100 isa<VectorType>(DestPTy)) {
9101 // If the source is an array, the code below will not succeed. Check to
9102 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
9104 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
9105 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
9106 if (ASrcTy->getNumElements() != 0) {
9108 Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
9109 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
9110 SrcTy = cast<PointerType>(CastOp->getType());
9111 SrcPTy = SrcTy->getElementType();
9114 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
9115 isa<VectorType>(SrcPTy)) &&
9116 // Do not allow turning this into a load of an integer, which is then
9117 // casted to a pointer, this pessimizes pointer analysis a lot.
9118 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
9119 IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
9120 IC.getTargetData().getTypeSizeInBits(DestPTy)) {
9122 // Okay, we are casting from one integer or pointer type to another of
9123 // the same size. Instead of casting the pointer before the load, cast
9124 // the result of the loaded value.
9125 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
9127 LI.isVolatile()),LI);
9128 // Now cast the result of the load.
9129 return new BitCastInst(NewLoad, LI.getType());
9136 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
9137 /// from this value cannot trap. If it is not obviously safe to load from the
9138 /// specified pointer, we do a quick local scan of the basic block containing
9139 /// ScanFrom, to determine if the address is already accessed.
9140 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
9141 // If it is an alloca it is always safe to load from.
9142 if (isa<AllocaInst>(V)) return true;
9144 // If it is a global variable it is mostly safe to load from.
9145 if (const GlobalValue *GV = dyn_cast<GlobalVariable>(V))
9146 // Don't try to evaluate aliases. External weak GV can be null.
9147 return !isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage();
9149 // Otherwise, be a little bit agressive by scanning the local block where we
9150 // want to check to see if the pointer is already being loaded or stored
9151 // from/to. If so, the previous load or store would have already trapped,
9152 // so there is no harm doing an extra load (also, CSE will later eliminate
9153 // the load entirely).
9154 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
9159 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
9160 if (LI->getOperand(0) == V) return true;
9161 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
9162 if (SI->getOperand(1) == V) return true;
9168 /// GetUnderlyingObject - Trace through a series of getelementptrs and bitcasts
9169 /// until we find the underlying object a pointer is referring to or something
9170 /// we don't understand. Note that the returned pointer may be offset from the
9171 /// input, because we ignore GEP indices.
9172 static Value *GetUnderlyingObject(Value *Ptr) {
9174 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) {
9175 if (CE->getOpcode() == Instruction::BitCast ||
9176 CE->getOpcode() == Instruction::GetElementPtr)
9177 Ptr = CE->getOperand(0);
9180 } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(Ptr)) {
9181 Ptr = BCI->getOperand(0);
9182 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
9183 Ptr = GEP->getOperand(0);
9190 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
9191 Value *Op = LI.getOperand(0);
9193 // Attempt to improve the alignment.
9194 unsigned KnownAlign = GetOrEnforceKnownAlignment(Op, TD);
9195 if (KnownAlign > LI.getAlignment())
9196 LI.setAlignment(KnownAlign);
9198 // load (cast X) --> cast (load X) iff safe
9199 if (isa<CastInst>(Op))
9200 if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
9203 // None of the following transforms are legal for volatile loads.
9204 if (LI.isVolatile()) return 0;
9206 if (&LI.getParent()->front() != &LI) {
9207 BasicBlock::iterator BBI = &LI; --BBI;
9208 // If the instruction immediately before this is a store to the same
9209 // address, do a simple form of store->load forwarding.
9210 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
9211 if (SI->getOperand(1) == LI.getOperand(0))
9212 return ReplaceInstUsesWith(LI, SI->getOperand(0));
9213 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
9214 if (LIB->getOperand(0) == LI.getOperand(0))
9215 return ReplaceInstUsesWith(LI, LIB);
9218 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
9219 if (isa<ConstantPointerNull>(GEPI->getOperand(0))) {
9220 // Insert a new store to null instruction before the load to indicate
9221 // that this code is not reachable. We do this instead of inserting
9222 // an unreachable instruction directly because we cannot modify the
9224 new StoreInst(UndefValue::get(LI.getType()),
9225 Constant::getNullValue(Op->getType()), &LI);
9226 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9229 if (Constant *C = dyn_cast<Constant>(Op)) {
9230 // load null/undef -> undef
9231 if ((C->isNullValue() || isa<UndefValue>(C))) {
9232 // Insert a new store to null instruction before the load to indicate that
9233 // this code is not reachable. We do this instead of inserting an
9234 // unreachable instruction directly because we cannot modify the CFG.
9235 new StoreInst(UndefValue::get(LI.getType()),
9236 Constant::getNullValue(Op->getType()), &LI);
9237 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9240 // Instcombine load (constant global) into the value loaded.
9241 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
9242 if (GV->isConstant() && !GV->isDeclaration())
9243 return ReplaceInstUsesWith(LI, GV->getInitializer());
9245 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
9246 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
9247 if (CE->getOpcode() == Instruction::GetElementPtr) {
9248 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
9249 if (GV->isConstant() && !GV->isDeclaration())
9251 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
9252 return ReplaceInstUsesWith(LI, V);
9253 if (CE->getOperand(0)->isNullValue()) {
9254 // Insert a new store to null instruction before the load to indicate
9255 // that this code is not reachable. We do this instead of inserting
9256 // an unreachable instruction directly because we cannot modify the
9258 new StoreInst(UndefValue::get(LI.getType()),
9259 Constant::getNullValue(Op->getType()), &LI);
9260 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9263 } else if (CE->isCast()) {
9264 if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
9269 // If this load comes from anywhere in a constant global, and if the global
9270 // is all undef or zero, we know what it loads.
9271 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(Op))) {
9272 if (GV->isConstant() && GV->hasInitializer()) {
9273 if (GV->getInitializer()->isNullValue())
9274 return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
9275 else if (isa<UndefValue>(GV->getInitializer()))
9276 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
9280 if (Op->hasOneUse()) {
9281 // Change select and PHI nodes to select values instead of addresses: this
9282 // helps alias analysis out a lot, allows many others simplifications, and
9283 // exposes redundancy in the code.
9285 // Note that we cannot do the transformation unless we know that the
9286 // introduced loads cannot trap! Something like this is valid as long as
9287 // the condition is always false: load (select bool %C, int* null, int* %G),
9288 // but it would not be valid if we transformed it to load from null
9291 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
9292 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
9293 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
9294 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
9295 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
9296 SI->getOperand(1)->getName()+".val"), LI);
9297 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
9298 SI->getOperand(2)->getName()+".val"), LI);
9299 return new SelectInst(SI->getCondition(), V1, V2);
9302 // load (select (cond, null, P)) -> load P
9303 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
9304 if (C->isNullValue()) {
9305 LI.setOperand(0, SI->getOperand(2));
9309 // load (select (cond, P, null)) -> load P
9310 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
9311 if (C->isNullValue()) {
9312 LI.setOperand(0, SI->getOperand(1));
9320 /// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
9322 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
9323 User *CI = cast<User>(SI.getOperand(1));
9324 Value *CastOp = CI->getOperand(0);
9326 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
9327 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
9328 const Type *SrcPTy = SrcTy->getElementType();
9330 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
9331 // If the source is an array, the code below will not succeed. Check to
9332 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
9334 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
9335 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
9336 if (ASrcTy->getNumElements() != 0) {
9338 Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
9339 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
9340 SrcTy = cast<PointerType>(CastOp->getType());
9341 SrcPTy = SrcTy->getElementType();
9344 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
9345 IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
9346 IC.getTargetData().getTypeSizeInBits(DestPTy)) {
9348 // Okay, we are casting from one integer or pointer type to another of
9349 // the same size. Instead of casting the pointer before
9350 // the store, cast the value to be stored.
9352 Value *SIOp0 = SI.getOperand(0);
9353 Instruction::CastOps opcode = Instruction::BitCast;
9354 const Type* CastSrcTy = SIOp0->getType();
9355 const Type* CastDstTy = SrcPTy;
9356 if (isa<PointerType>(CastDstTy)) {
9357 if (CastSrcTy->isInteger())
9358 opcode = Instruction::IntToPtr;
9359 } else if (isa<IntegerType>(CastDstTy)) {
9360 if (isa<PointerType>(SIOp0->getType()))
9361 opcode = Instruction::PtrToInt;
9363 if (Constant *C = dyn_cast<Constant>(SIOp0))
9364 NewCast = ConstantExpr::getCast(opcode, C, CastDstTy);
9366 NewCast = IC.InsertNewInstBefore(
9367 CastInst::create(opcode, SIOp0, CastDstTy, SIOp0->getName()+".c"),
9369 return new StoreInst(NewCast, CastOp);
9376 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
9377 Value *Val = SI.getOperand(0);
9378 Value *Ptr = SI.getOperand(1);
9380 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
9381 EraseInstFromFunction(SI);
9386 // If the RHS is an alloca with a single use, zapify the store, making the
9388 if (Ptr->hasOneUse()) {
9389 if (isa<AllocaInst>(Ptr)) {
9390 EraseInstFromFunction(SI);
9395 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
9396 if (isa<AllocaInst>(GEP->getOperand(0)) &&
9397 GEP->getOperand(0)->hasOneUse()) {
9398 EraseInstFromFunction(SI);
9404 // Attempt to improve the alignment.
9405 unsigned KnownAlign = GetOrEnforceKnownAlignment(Ptr, TD);
9406 if (KnownAlign > SI.getAlignment())
9407 SI.setAlignment(KnownAlign);
9409 // Do really simple DSE, to catch cases where there are several consequtive
9410 // stores to the same location, separated by a few arithmetic operations. This
9411 // situation often occurs with bitfield accesses.
9412 BasicBlock::iterator BBI = &SI;
9413 for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
9417 if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
9418 // Prev store isn't volatile, and stores to the same location?
9419 if (!PrevSI->isVolatile() && PrevSI->getOperand(1) == SI.getOperand(1)) {
9422 EraseInstFromFunction(*PrevSI);
9428 // If this is a load, we have to stop. However, if the loaded value is from
9429 // the pointer we're loading and is producing the pointer we're storing,
9430 // then *this* store is dead (X = load P; store X -> P).
9431 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
9432 if (LI == Val && LI->getOperand(0) == Ptr && !SI.isVolatile()) {
9433 EraseInstFromFunction(SI);
9437 // Otherwise, this is a load from some other location. Stores before it
9442 // Don't skip over loads or things that can modify memory.
9443 if (BBI->mayWriteToMemory())
9448 if (SI.isVolatile()) return 0; // Don't hack volatile stores.
9450 // store X, null -> turns into 'unreachable' in SimplifyCFG
9451 if (isa<ConstantPointerNull>(Ptr)) {
9452 if (!isa<UndefValue>(Val)) {
9453 SI.setOperand(0, UndefValue::get(Val->getType()));
9454 if (Instruction *U = dyn_cast<Instruction>(Val))
9455 AddToWorkList(U); // Dropped a use.
9458 return 0; // Do not modify these!
9461 // store undef, Ptr -> noop
9462 if (isa<UndefValue>(Val)) {
9463 EraseInstFromFunction(SI);
9468 // If the pointer destination is a cast, see if we can fold the cast into the
9470 if (isa<CastInst>(Ptr))
9471 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
9473 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
9475 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
9479 // If this store is the last instruction in the basic block, and if the block
9480 // ends with an unconditional branch, try to move it to the successor block.
9482 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
9483 if (BI->isUnconditional())
9484 if (SimplifyStoreAtEndOfBlock(SI))
9485 return 0; // xform done!
9490 /// SimplifyStoreAtEndOfBlock - Turn things like:
9491 /// if () { *P = v1; } else { *P = v2 }
9492 /// into a phi node with a store in the successor.
9494 /// Simplify things like:
9495 /// *P = v1; if () { *P = v2; }
9496 /// into a phi node with a store in the successor.
9498 bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
9499 BasicBlock *StoreBB = SI.getParent();
9501 // Check to see if the successor block has exactly two incoming edges. If
9502 // so, see if the other predecessor contains a store to the same location.
9503 // if so, insert a PHI node (if needed) and move the stores down.
9504 BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
9506 // Determine whether Dest has exactly two predecessors and, if so, compute
9507 // the other predecessor.
9508 pred_iterator PI = pred_begin(DestBB);
9509 BasicBlock *OtherBB = 0;
9513 if (PI == pred_end(DestBB))
9516 if (*PI != StoreBB) {
9521 if (++PI != pred_end(DestBB))
9525 // Verify that the other block ends in a branch and is not otherwise empty.
9526 BasicBlock::iterator BBI = OtherBB->getTerminator();
9527 BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
9528 if (!OtherBr || BBI == OtherBB->begin())
9531 // If the other block ends in an unconditional branch, check for the 'if then
9532 // else' case. there is an instruction before the branch.
9533 StoreInst *OtherStore = 0;
9534 if (OtherBr->isUnconditional()) {
9535 // If this isn't a store, or isn't a store to the same location, bail out.
9537 OtherStore = dyn_cast<StoreInst>(BBI);
9538 if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1))
9541 // Otherwise, the other block ended with a conditional branch. If one of the
9542 // destinations is StoreBB, then we have the if/then case.
9543 if (OtherBr->getSuccessor(0) != StoreBB &&
9544 OtherBr->getSuccessor(1) != StoreBB)
9547 // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
9548 // if/then triangle. See if there is a store to the same ptr as SI that
9549 // lives in OtherBB.
9551 // Check to see if we find the matching store.
9552 if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
9553 if (OtherStore->getOperand(1) != SI.getOperand(1))
9557 // If we find something that may be using the stored value, or if we run
9558 // out of instructions, we can't do the xform.
9559 if (isa<LoadInst>(BBI) || BBI->mayWriteToMemory() ||
9560 BBI == OtherBB->begin())
9564 // In order to eliminate the store in OtherBr, we have to
9565 // make sure nothing reads the stored value in StoreBB.
9566 for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
9567 // FIXME: This should really be AA driven.
9568 if (isa<LoadInst>(I) || I->mayWriteToMemory())
9573 // Insert a PHI node now if we need it.
9574 Value *MergedVal = OtherStore->getOperand(0);
9575 if (MergedVal != SI.getOperand(0)) {
9576 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
9577 PN->reserveOperandSpace(2);
9578 PN->addIncoming(SI.getOperand(0), SI.getParent());
9579 PN->addIncoming(OtherStore->getOperand(0), OtherBB);
9580 MergedVal = InsertNewInstBefore(PN, DestBB->front());
9583 // Advance to a place where it is safe to insert the new store and
9585 BBI = DestBB->begin();
9586 while (isa<PHINode>(BBI)) ++BBI;
9587 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
9588 OtherStore->isVolatile()), *BBI);
9590 // Nuke the old stores.
9591 EraseInstFromFunction(SI);
9592 EraseInstFromFunction(*OtherStore);
9598 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
9599 // Change br (not X), label True, label False to: br X, label False, True
9601 BasicBlock *TrueDest;
9602 BasicBlock *FalseDest;
9603 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
9604 !isa<Constant>(X)) {
9605 // Swap Destinations and condition...
9607 BI.setSuccessor(0, FalseDest);
9608 BI.setSuccessor(1, TrueDest);
9612 // Cannonicalize fcmp_one -> fcmp_oeq
9613 FCmpInst::Predicate FPred; Value *Y;
9614 if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
9615 TrueDest, FalseDest)))
9616 if ((FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
9617 FPred == FCmpInst::FCMP_OGE) && BI.getCondition()->hasOneUse()) {
9618 FCmpInst *I = cast<FCmpInst>(BI.getCondition());
9619 FCmpInst::Predicate NewPred = FCmpInst::getInversePredicate(FPred);
9620 Instruction *NewSCC = new FCmpInst(NewPred, X, Y, "", I);
9621 NewSCC->takeName(I);
9622 // Swap Destinations and condition...
9623 BI.setCondition(NewSCC);
9624 BI.setSuccessor(0, FalseDest);
9625 BI.setSuccessor(1, TrueDest);
9626 RemoveFromWorkList(I);
9627 I->eraseFromParent();
9628 AddToWorkList(NewSCC);
9632 // Cannonicalize icmp_ne -> icmp_eq
9633 ICmpInst::Predicate IPred;
9634 if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
9635 TrueDest, FalseDest)))
9636 if ((IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
9637 IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
9638 IPred == ICmpInst::ICMP_SGE) && BI.getCondition()->hasOneUse()) {
9639 ICmpInst *I = cast<ICmpInst>(BI.getCondition());
9640 ICmpInst::Predicate NewPred = ICmpInst::getInversePredicate(IPred);
9641 Instruction *NewSCC = new ICmpInst(NewPred, X, Y, "", I);
9642 NewSCC->takeName(I);
9643 // Swap Destinations and condition...
9644 BI.setCondition(NewSCC);
9645 BI.setSuccessor(0, FalseDest);
9646 BI.setSuccessor(1, TrueDest);
9647 RemoveFromWorkList(I);
9648 I->eraseFromParent();;
9649 AddToWorkList(NewSCC);
9656 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
9657 Value *Cond = SI.getCondition();
9658 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
9659 if (I->getOpcode() == Instruction::Add)
9660 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
9661 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
9662 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
9663 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
9665 SI.setOperand(0, I->getOperand(0));
9673 /// CheapToScalarize - Return true if the value is cheaper to scalarize than it
9674 /// is to leave as a vector operation.
9675 static bool CheapToScalarize(Value *V, bool isConstant) {
9676 if (isa<ConstantAggregateZero>(V))
9678 if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
9679 if (isConstant) return true;
9680 // If all elts are the same, we can extract.
9681 Constant *Op0 = C->getOperand(0);
9682 for (unsigned i = 1; i < C->getNumOperands(); ++i)
9683 if (C->getOperand(i) != Op0)
9687 Instruction *I = dyn_cast<Instruction>(V);
9688 if (!I) return false;
9690 // Insert element gets simplified to the inserted element or is deleted if
9691 // this is constant idx extract element and its a constant idx insertelt.
9692 if (I->getOpcode() == Instruction::InsertElement && isConstant &&
9693 isa<ConstantInt>(I->getOperand(2)))
9695 if (I->getOpcode() == Instruction::Load && I->hasOneUse())
9697 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
9698 if (BO->hasOneUse() &&
9699 (CheapToScalarize(BO->getOperand(0), isConstant) ||
9700 CheapToScalarize(BO->getOperand(1), isConstant)))
9702 if (CmpInst *CI = dyn_cast<CmpInst>(I))
9703 if (CI->hasOneUse() &&
9704 (CheapToScalarize(CI->getOperand(0), isConstant) ||
9705 CheapToScalarize(CI->getOperand(1), isConstant)))
9711 /// Read and decode a shufflevector mask.
9713 /// It turns undef elements into values that are larger than the number of
9714 /// elements in the input.
9715 static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
9716 unsigned NElts = SVI->getType()->getNumElements();
9717 if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
9718 return std::vector<unsigned>(NElts, 0);
9719 if (isa<UndefValue>(SVI->getOperand(2)))
9720 return std::vector<unsigned>(NElts, 2*NElts);
9722 std::vector<unsigned> Result;
9723 const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
9724 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
9725 if (isa<UndefValue>(CP->getOperand(i)))
9726 Result.push_back(NElts*2); // undef -> 8
9728 Result.push_back(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
9732 /// FindScalarElement - Given a vector and an element number, see if the scalar
9733 /// value is already around as a register, for example if it were inserted then
9734 /// extracted from the vector.
9735 static Value *FindScalarElement(Value *V, unsigned EltNo) {
9736 assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
9737 const VectorType *PTy = cast<VectorType>(V->getType());
9738 unsigned Width = PTy->getNumElements();
9739 if (EltNo >= Width) // Out of range access.
9740 return UndefValue::get(PTy->getElementType());
9742 if (isa<UndefValue>(V))
9743 return UndefValue::get(PTy->getElementType());
9744 else if (isa<ConstantAggregateZero>(V))
9745 return Constant::getNullValue(PTy->getElementType());
9746 else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
9747 return CP->getOperand(EltNo);
9748 else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
9749 // If this is an insert to a variable element, we don't know what it is.
9750 if (!isa<ConstantInt>(III->getOperand(2)))
9752 unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
9754 // If this is an insert to the element we are looking for, return the
9757 return III->getOperand(1);
9759 // Otherwise, the insertelement doesn't modify the value, recurse on its
9761 return FindScalarElement(III->getOperand(0), EltNo);
9762 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
9763 unsigned InEl = getShuffleMask(SVI)[EltNo];
9765 return FindScalarElement(SVI->getOperand(0), InEl);
9766 else if (InEl < Width*2)
9767 return FindScalarElement(SVI->getOperand(1), InEl - Width);
9769 return UndefValue::get(PTy->getElementType());
9772 // Otherwise, we don't know.
9776 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
9778 // If vector val is undef, replace extract with scalar undef.
9779 if (isa<UndefValue>(EI.getOperand(0)))
9780 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9782 // If vector val is constant 0, replace extract with scalar 0.
9783 if (isa<ConstantAggregateZero>(EI.getOperand(0)))
9784 return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
9786 if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
9787 // If vector val is constant with uniform operands, replace EI
9788 // with that operand
9789 Constant *op0 = C->getOperand(0);
9790 for (unsigned i = 1; i < C->getNumOperands(); ++i)
9791 if (C->getOperand(i) != op0) {
9796 return ReplaceInstUsesWith(EI, op0);
9799 // If extracting a specified index from the vector, see if we can recursively
9800 // find a previously computed scalar that was inserted into the vector.
9801 if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
9802 unsigned IndexVal = IdxC->getZExtValue();
9803 unsigned VectorWidth =
9804 cast<VectorType>(EI.getOperand(0)->getType())->getNumElements();
9806 // If this is extracting an invalid index, turn this into undef, to avoid
9807 // crashing the code below.
9808 if (IndexVal >= VectorWidth)
9809 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9811 // This instruction only demands the single element from the input vector.
9812 // If the input vector has a single use, simplify it based on this use
9814 if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
9816 if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
9819 EI.setOperand(0, V);
9824 if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
9825 return ReplaceInstUsesWith(EI, Elt);
9827 // If the this extractelement is directly using a bitcast from a vector of
9828 // the same number of elements, see if we can find the source element from
9829 // it. In this case, we will end up needing to bitcast the scalars.
9830 if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
9831 if (const VectorType *VT =
9832 dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
9833 if (VT->getNumElements() == VectorWidth)
9834 if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
9835 return new BitCastInst(Elt, EI.getType());
9839 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
9840 if (I->hasOneUse()) {
9841 // Push extractelement into predecessor operation if legal and
9842 // profitable to do so
9843 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
9844 bool isConstantElt = isa<ConstantInt>(EI.getOperand(1));
9845 if (CheapToScalarize(BO, isConstantElt)) {
9846 ExtractElementInst *newEI0 =
9847 new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
9848 EI.getName()+".lhs");
9849 ExtractElementInst *newEI1 =
9850 new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
9851 EI.getName()+".rhs");
9852 InsertNewInstBefore(newEI0, EI);
9853 InsertNewInstBefore(newEI1, EI);
9854 return BinaryOperator::create(BO->getOpcode(), newEI0, newEI1);
9856 } else if (isa<LoadInst>(I)) {
9857 Value *Ptr = InsertCastBefore(Instruction::BitCast, I->getOperand(0),
9858 PointerType::get(EI.getType()), EI);
9859 GetElementPtrInst *GEP =
9860 new GetElementPtrInst(Ptr, EI.getOperand(1), I->getName() + ".gep");
9861 InsertNewInstBefore(GEP, EI);
9862 return new LoadInst(GEP);
9865 if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
9866 // Extracting the inserted element?
9867 if (IE->getOperand(2) == EI.getOperand(1))
9868 return ReplaceInstUsesWith(EI, IE->getOperand(1));
9869 // If the inserted and extracted elements are constants, they must not
9870 // be the same value, extract from the pre-inserted value instead.
9871 if (isa<Constant>(IE->getOperand(2)) &&
9872 isa<Constant>(EI.getOperand(1))) {
9873 AddUsesToWorkList(EI);
9874 EI.setOperand(0, IE->getOperand(0));
9877 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
9878 // If this is extracting an element from a shufflevector, figure out where
9879 // it came from and extract from the appropriate input element instead.
9880 if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
9881 unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
9883 if (SrcIdx < SVI->getType()->getNumElements())
9884 Src = SVI->getOperand(0);
9885 else if (SrcIdx < SVI->getType()->getNumElements()*2) {
9886 SrcIdx -= SVI->getType()->getNumElements();
9887 Src = SVI->getOperand(1);
9889 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9891 return new ExtractElementInst(Src, SrcIdx);
9898 /// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
9899 /// elements from either LHS or RHS, return the shuffle mask and true.
9900 /// Otherwise, return false.
9901 static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
9902 std::vector<Constant*> &Mask) {
9903 assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
9904 "Invalid CollectSingleShuffleElements");
9905 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
9907 if (isa<UndefValue>(V)) {
9908 Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
9910 } else if (V == LHS) {
9911 for (unsigned i = 0; i != NumElts; ++i)
9912 Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
9914 } else if (V == RHS) {
9915 for (unsigned i = 0; i != NumElts; ++i)
9916 Mask.push_back(ConstantInt::get(Type::Int32Ty, i+NumElts));
9918 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
9919 // If this is an insert of an extract from some other vector, include it.
9920 Value *VecOp = IEI->getOperand(0);
9921 Value *ScalarOp = IEI->getOperand(1);
9922 Value *IdxOp = IEI->getOperand(2);
9924 if (!isa<ConstantInt>(IdxOp))
9926 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
9928 if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
9929 // Okay, we can handle this if the vector we are insertinting into is
9931 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
9932 // If so, update the mask to reflect the inserted undef.
9933 Mask[InsertedIdx] = UndefValue::get(Type::Int32Ty);
9936 } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
9937 if (isa<ConstantInt>(EI->getOperand(1)) &&
9938 EI->getOperand(0)->getType() == V->getType()) {
9939 unsigned ExtractedIdx =
9940 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
9942 // This must be extracting from either LHS or RHS.
9943 if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
9944 // Okay, we can handle this if the vector we are insertinting into is
9946 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
9947 // If so, update the mask to reflect the inserted value.
9948 if (EI->getOperand(0) == LHS) {
9949 Mask[InsertedIdx & (NumElts-1)] =
9950 ConstantInt::get(Type::Int32Ty, ExtractedIdx);
9952 assert(EI->getOperand(0) == RHS);
9953 Mask[InsertedIdx & (NumElts-1)] =
9954 ConstantInt::get(Type::Int32Ty, ExtractedIdx+NumElts);
9963 // TODO: Handle shufflevector here!
9968 /// CollectShuffleElements - We are building a shuffle of V, using RHS as the
9969 /// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
9970 /// that computes V and the LHS value of the shuffle.
9971 static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
9973 assert(isa<VectorType>(V->getType()) &&
9974 (RHS == 0 || V->getType() == RHS->getType()) &&
9975 "Invalid shuffle!");
9976 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
9978 if (isa<UndefValue>(V)) {
9979 Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
9981 } else if (isa<ConstantAggregateZero>(V)) {
9982 Mask.assign(NumElts, ConstantInt::get(Type::Int32Ty, 0));
9984 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
9985 // If this is an insert of an extract from some other vector, include it.
9986 Value *VecOp = IEI->getOperand(0);
9987 Value *ScalarOp = IEI->getOperand(1);
9988 Value *IdxOp = IEI->getOperand(2);
9990 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
9991 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
9992 EI->getOperand(0)->getType() == V->getType()) {
9993 unsigned ExtractedIdx =
9994 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
9995 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
9997 // Either the extracted from or inserted into vector must be RHSVec,
9998 // otherwise we'd end up with a shuffle of three inputs.
9999 if (EI->getOperand(0) == RHS || RHS == 0) {
10000 RHS = EI->getOperand(0);
10001 Value *V = CollectShuffleElements(VecOp, Mask, RHS);
10002 Mask[InsertedIdx & (NumElts-1)] =
10003 ConstantInt::get(Type::Int32Ty, NumElts+ExtractedIdx);
10007 if (VecOp == RHS) {
10008 Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
10009 // Everything but the extracted element is replaced with the RHS.
10010 for (unsigned i = 0; i != NumElts; ++i) {
10011 if (i != InsertedIdx)
10012 Mask[i] = ConstantInt::get(Type::Int32Ty, NumElts+i);
10017 // If this insertelement is a chain that comes from exactly these two
10018 // vectors, return the vector and the effective shuffle.
10019 if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
10020 return EI->getOperand(0);
10025 // TODO: Handle shufflevector here!
10027 // Otherwise, can't do anything fancy. Return an identity vector.
10028 for (unsigned i = 0; i != NumElts; ++i)
10029 Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
10033 Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
10034 Value *VecOp = IE.getOperand(0);
10035 Value *ScalarOp = IE.getOperand(1);
10036 Value *IdxOp = IE.getOperand(2);
10038 // Inserting an undef or into an undefined place, remove this.
10039 if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
10040 ReplaceInstUsesWith(IE, VecOp);
10042 // If the inserted element was extracted from some other vector, and if the
10043 // indexes are constant, try to turn this into a shufflevector operation.
10044 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
10045 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
10046 EI->getOperand(0)->getType() == IE.getType()) {
10047 unsigned NumVectorElts = IE.getType()->getNumElements();
10048 unsigned ExtractedIdx =
10049 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
10050 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
10052 if (ExtractedIdx >= NumVectorElts) // Out of range extract.
10053 return ReplaceInstUsesWith(IE, VecOp);
10055 if (InsertedIdx >= NumVectorElts) // Out of range insert.
10056 return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
10058 // If we are extracting a value from a vector, then inserting it right
10059 // back into the same place, just use the input vector.
10060 if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
10061 return ReplaceInstUsesWith(IE, VecOp);
10063 // We could theoretically do this for ANY input. However, doing so could
10064 // turn chains of insertelement instructions into a chain of shufflevector
10065 // instructions, and right now we do not merge shufflevectors. As such,
10066 // only do this in a situation where it is clear that there is benefit.
10067 if (isa<UndefValue>(VecOp) || isa<ConstantAggregateZero>(VecOp)) {
10068 // Turn this into shuffle(EIOp0, VecOp, Mask). The result has all of
10069 // the values of VecOp, except then one read from EIOp0.
10070 // Build a new shuffle mask.
10071 std::vector<Constant*> Mask;
10072 if (isa<UndefValue>(VecOp))
10073 Mask.assign(NumVectorElts, UndefValue::get(Type::Int32Ty));
10075 assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing");
10076 Mask.assign(NumVectorElts, ConstantInt::get(Type::Int32Ty,
10079 Mask[InsertedIdx] = ConstantInt::get(Type::Int32Ty, ExtractedIdx);
10080 return new ShuffleVectorInst(EI->getOperand(0), VecOp,
10081 ConstantVector::get(Mask));
10084 // If this insertelement isn't used by some other insertelement, turn it
10085 // (and any insertelements it points to), into one big shuffle.
10086 if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
10087 std::vector<Constant*> Mask;
10089 Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
10090 if (RHS == 0) RHS = UndefValue::get(LHS->getType());
10091 // We now have a shuffle of LHS, RHS, Mask.
10092 return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask));
10101 Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
10102 Value *LHS = SVI.getOperand(0);
10103 Value *RHS = SVI.getOperand(1);
10104 std::vector<unsigned> Mask = getShuffleMask(&SVI);
10106 bool MadeChange = false;
10108 // Undefined shuffle mask -> undefined value.
10109 if (isa<UndefValue>(SVI.getOperand(2)))
10110 return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
10112 // If we have shuffle(x, undef, mask) and any elements of mask refer to
10113 // the undef, change them to undefs.
10114 if (isa<UndefValue>(SVI.getOperand(1))) {
10115 // Scan to see if there are any references to the RHS. If so, replace them
10116 // with undef element refs and set MadeChange to true.
10117 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
10118 if (Mask[i] >= e && Mask[i] != 2*e) {
10125 // Remap any references to RHS to use LHS.
10126 std::vector<Constant*> Elts;
10127 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
10128 if (Mask[i] == 2*e)
10129 Elts.push_back(UndefValue::get(Type::Int32Ty));
10131 Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
10133 SVI.setOperand(2, ConstantVector::get(Elts));
10137 // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
10138 // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
10139 if (LHS == RHS || isa<UndefValue>(LHS)) {
10140 if (isa<UndefValue>(LHS) && LHS == RHS) {
10141 // shuffle(undef,undef,mask) -> undef.
10142 return ReplaceInstUsesWith(SVI, LHS);
10145 // Remap any references to RHS to use LHS.
10146 std::vector<Constant*> Elts;
10147 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
10148 if (Mask[i] >= 2*e)
10149 Elts.push_back(UndefValue::get(Type::Int32Ty));
10151 if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
10152 (Mask[i] < e && isa<UndefValue>(LHS)))
10153 Mask[i] = 2*e; // Turn into undef.
10155 Mask[i] &= (e-1); // Force to LHS.
10156 Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
10159 SVI.setOperand(0, SVI.getOperand(1));
10160 SVI.setOperand(1, UndefValue::get(RHS->getType()));
10161 SVI.setOperand(2, ConstantVector::get(Elts));
10162 LHS = SVI.getOperand(0);
10163 RHS = SVI.getOperand(1);
10167 // Analyze the shuffle, are the LHS or RHS and identity shuffles?
10168 bool isLHSID = true, isRHSID = true;
10170 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
10171 if (Mask[i] >= e*2) continue; // Ignore undef values.
10172 // Is this an identity shuffle of the LHS value?
10173 isLHSID &= (Mask[i] == i);
10175 // Is this an identity shuffle of the RHS value?
10176 isRHSID &= (Mask[i]-e == i);
10179 // Eliminate identity shuffles.
10180 if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
10181 if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
10183 // If the LHS is a shufflevector itself, see if we can combine it with this
10184 // one without producing an unusual shuffle. Here we are really conservative:
10185 // we are absolutely afraid of producing a shuffle mask not in the input
10186 // program, because the code gen may not be smart enough to turn a merged
10187 // shuffle into two specific shuffles: it may produce worse code. As such,
10188 // we only merge two shuffles if the result is one of the two input shuffle
10189 // masks. In this case, merging the shuffles just removes one instruction,
10190 // which we know is safe. This is good for things like turning:
10191 // (splat(splat)) -> splat.
10192 if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
10193 if (isa<UndefValue>(RHS)) {
10194 std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
10196 std::vector<unsigned> NewMask;
10197 for (unsigned i = 0, e = Mask.size(); i != e; ++i)
10198 if (Mask[i] >= 2*e)
10199 NewMask.push_back(2*e);
10201 NewMask.push_back(LHSMask[Mask[i]]);
10203 // If the result mask is equal to the src shuffle or this shuffle mask, do
10204 // the replacement.
10205 if (NewMask == LHSMask || NewMask == Mask) {
10206 std::vector<Constant*> Elts;
10207 for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
10208 if (NewMask[i] >= e*2) {
10209 Elts.push_back(UndefValue::get(Type::Int32Ty));
10211 Elts.push_back(ConstantInt::get(Type::Int32Ty, NewMask[i]));
10214 return new ShuffleVectorInst(LHSSVI->getOperand(0),
10215 LHSSVI->getOperand(1),
10216 ConstantVector::get(Elts));
10221 return MadeChange ? &SVI : 0;
10227 /// TryToSinkInstruction - Try to move the specified instruction from its
10228 /// current block into the beginning of DestBlock, which can only happen if it's
10229 /// safe to move the instruction past all of the instructions between it and the
10230 /// end of its block.
10231 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
10232 assert(I->hasOneUse() && "Invariants didn't hold!");
10234 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
10235 if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
10237 // Do not sink alloca instructions out of the entry block.
10238 if (isa<AllocaInst>(I) && I->getParent() ==
10239 &DestBlock->getParent()->getEntryBlock())
10242 // We can only sink load instructions if there is nothing between the load and
10243 // the end of block that could change the value.
10244 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
10245 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
10247 if (Scan->mayWriteToMemory())
10251 BasicBlock::iterator InsertPos = DestBlock->begin();
10252 while (isa<PHINode>(InsertPos)) ++InsertPos;
10254 I->moveBefore(InsertPos);
10260 /// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
10261 /// all reachable code to the worklist.
10263 /// This has a couple of tricks to make the code faster and more powerful. In
10264 /// particular, we constant fold and DCE instructions as we go, to avoid adding
10265 /// them to the worklist (this significantly speeds up instcombine on code where
10266 /// many instructions are dead or constant). Additionally, if we find a branch
10267 /// whose condition is a known constant, we only visit the reachable successors.
10269 static void AddReachableCodeToWorklist(BasicBlock *BB,
10270 SmallPtrSet<BasicBlock*, 64> &Visited,
10272 const TargetData *TD) {
10273 std::vector<BasicBlock*> Worklist;
10274 Worklist.push_back(BB);
10276 while (!Worklist.empty()) {
10277 BB = Worklist.back();
10278 Worklist.pop_back();
10280 // We have now visited this block! If we've already been here, ignore it.
10281 if (!Visited.insert(BB)) continue;
10283 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
10284 Instruction *Inst = BBI++;
10286 // DCE instruction if trivially dead.
10287 if (isInstructionTriviallyDead(Inst)) {
10289 DOUT << "IC: DCE: " << *Inst;
10290 Inst->eraseFromParent();
10294 // ConstantProp instruction if trivially constant.
10295 if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
10296 DOUT << "IC: ConstFold to: " << *C << " from: " << *Inst;
10297 Inst->replaceAllUsesWith(C);
10299 Inst->eraseFromParent();
10303 IC.AddToWorkList(Inst);
10306 // Recursively visit successors. If this is a branch or switch on a
10307 // constant, only visit the reachable successor.
10308 TerminatorInst *TI = BB->getTerminator();
10309 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
10310 if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
10311 bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
10312 Worklist.push_back(BI->getSuccessor(!CondVal));
10315 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
10316 if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
10317 // See if this is an explicit destination.
10318 for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
10319 if (SI->getCaseValue(i) == Cond) {
10320 Worklist.push_back(SI->getSuccessor(i));
10324 // Otherwise it is the default destination.
10325 Worklist.push_back(SI->getSuccessor(0));
10330 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
10331 Worklist.push_back(TI->getSuccessor(i));
10335 bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
10336 bool Changed = false;
10337 TD = &getAnalysis<TargetData>();
10339 DEBUG(DOUT << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
10340 << F.getNameStr() << "\n");
10343 // Do a depth-first traversal of the function, populate the worklist with
10344 // the reachable instructions. Ignore blocks that are not reachable. Keep
10345 // track of which blocks we visit.
10346 SmallPtrSet<BasicBlock*, 64> Visited;
10347 AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
10349 // Do a quick scan over the function. If we find any blocks that are
10350 // unreachable, remove any instructions inside of them. This prevents
10351 // the instcombine code from having to deal with some bad special cases.
10352 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
10353 if (!Visited.count(BB)) {
10354 Instruction *Term = BB->getTerminator();
10355 while (Term != BB->begin()) { // Remove instrs bottom-up
10356 BasicBlock::iterator I = Term; --I;
10358 DOUT << "IC: DCE: " << *I;
10361 if (!I->use_empty())
10362 I->replaceAllUsesWith(UndefValue::get(I->getType()));
10363 I->eraseFromParent();
10368 while (!Worklist.empty()) {
10369 Instruction *I = RemoveOneFromWorkList();
10370 if (I == 0) continue; // skip null values.
10372 // Check to see if we can DCE the instruction.
10373 if (isInstructionTriviallyDead(I)) {
10374 // Add operands to the worklist.
10375 if (I->getNumOperands() < 4)
10376 AddUsesToWorkList(*I);
10379 DOUT << "IC: DCE: " << *I;
10381 I->eraseFromParent();
10382 RemoveFromWorkList(I);
10386 // Instruction isn't dead, see if we can constant propagate it.
10387 if (Constant *C = ConstantFoldInstruction(I, TD)) {
10388 DOUT << "IC: ConstFold to: " << *C << " from: " << *I;
10390 // Add operands to the worklist.
10391 AddUsesToWorkList(*I);
10392 ReplaceInstUsesWith(*I, C);
10395 I->eraseFromParent();
10396 RemoveFromWorkList(I);
10400 // See if we can trivially sink this instruction to a successor basic block.
10401 if (I->hasOneUse()) {
10402 BasicBlock *BB = I->getParent();
10403 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
10404 if (UserParent != BB) {
10405 bool UserIsSuccessor = false;
10406 // See if the user is one of our successors.
10407 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
10408 if (*SI == UserParent) {
10409 UserIsSuccessor = true;
10413 // If the user is one of our immediate successors, and if that successor
10414 // only has us as a predecessors (we'd have to split the critical edge
10415 // otherwise), we can keep going.
10416 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
10417 next(pred_begin(UserParent)) == pred_end(UserParent))
10418 // Okay, the CFG is simple enough, try to sink this instruction.
10419 Changed |= TryToSinkInstruction(I, UserParent);
10423 // Now that we have an instruction, try combining it to simplify it...
10427 DEBUG(std::ostringstream SS; I->print(SS); OrigI = SS.str(););
10428 if (Instruction *Result = visit(*I)) {
10430 // Should we replace the old instruction with a new one?
10432 DOUT << "IC: Old = " << *I
10433 << " New = " << *Result;
10435 // Everything uses the new instruction now.
10436 I->replaceAllUsesWith(Result);
10438 // Push the new instruction and any users onto the worklist.
10439 AddToWorkList(Result);
10440 AddUsersToWorkList(*Result);
10442 // Move the name to the new instruction first.
10443 Result->takeName(I);
10445 // Insert the new instruction into the basic block...
10446 BasicBlock *InstParent = I->getParent();
10447 BasicBlock::iterator InsertPos = I;
10449 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
10450 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
10453 InstParent->getInstList().insert(InsertPos, Result);
10455 // Make sure that we reprocess all operands now that we reduced their
10457 AddUsesToWorkList(*I);
10459 // Instructions can end up on the worklist more than once. Make sure
10460 // we do not process an instruction that has been deleted.
10461 RemoveFromWorkList(I);
10463 // Erase the old instruction.
10464 InstParent->getInstList().erase(I);
10467 DOUT << "IC: Mod = " << OrigI
10468 << " New = " << *I;
10471 // If the instruction was modified, it's possible that it is now dead.
10472 // if so, remove it.
10473 if (isInstructionTriviallyDead(I)) {
10474 // Make sure we process all operands now that we are reducing their
10476 AddUsesToWorkList(*I);
10478 // Instructions may end up in the worklist more than once. Erase all
10479 // occurrences of this instruction.
10480 RemoveFromWorkList(I);
10481 I->eraseFromParent();
10484 AddUsersToWorkList(*I);
10491 assert(WorklistMap.empty() && "Worklist empty, but map not?");
10493 // Do an explicit clear, this shrinks the map if needed.
10494 WorklistMap.clear();
10499 bool InstCombiner::runOnFunction(Function &F) {
10500 MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
10502 bool EverMadeChange = false;
10504 // Iterate while there is work to do.
10505 unsigned Iteration = 0;
10506 while (DoOneIteration(F, Iteration++))
10507 EverMadeChange = true;
10508 return EverMadeChange;
10511 FunctionPass *llvm::createInstructionCombiningPass() {
10512 return new InstCombiner();