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. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All SetCC 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/Target/TargetData.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Support/CallSite.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/GetElementPtrTypeIterator.h"
48 #include "llvm/Support/InstVisitor.h"
49 #include "llvm/Support/MathExtras.h"
50 #include "llvm/Support/PatternMatch.h"
51 #include "llvm/ADT/DepthFirstIterator.h"
52 #include "llvm/ADT/Statistic.h"
53 #include "llvm/ADT/STLExtras.h"
57 using namespace llvm::PatternMatch;
60 Statistic<> NumCombined ("instcombine", "Number of insts combined");
61 Statistic<> NumConstProp("instcombine", "Number of constant folds");
62 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
63 Statistic<> NumDeadStore("instcombine", "Number of dead stores eliminated");
64 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
66 class InstCombiner : public FunctionPass,
67 public InstVisitor<InstCombiner, Instruction*> {
68 // Worklist of all of the instructions that need to be simplified.
69 std::vector<Instruction*> WorkList;
72 /// AddUsersToWorkList - When an instruction is simplified, add all users of
73 /// the instruction to the work lists because they might get more simplified
76 void AddUsersToWorkList(Value &I) {
77 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
79 WorkList.push_back(cast<Instruction>(*UI));
82 /// AddUsesToWorkList - When an instruction is simplified, add operands to
83 /// the work lists because they might get more simplified now.
85 void AddUsesToWorkList(Instruction &I) {
86 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
87 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
88 WorkList.push_back(Op);
91 // removeFromWorkList - remove all instances of I from the worklist.
92 void removeFromWorkList(Instruction *I);
94 virtual bool runOnFunction(Function &F);
96 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
97 AU.addRequired<TargetData>();
101 TargetData &getTargetData() const { return *TD; }
103 // Visitation implementation - Implement instruction combining for different
104 // instruction types. The semantics are as follows:
106 // null - No change was made
107 // I - Change was made, I is still valid, I may be dead though
108 // otherwise - Change was made, replace I with returned instruction
110 Instruction *visitAdd(BinaryOperator &I);
111 Instruction *visitSub(BinaryOperator &I);
112 Instruction *visitMul(BinaryOperator &I);
113 Instruction *visitDiv(BinaryOperator &I);
114 Instruction *visitRem(BinaryOperator &I);
115 Instruction *visitAnd(BinaryOperator &I);
116 Instruction *visitOr (BinaryOperator &I);
117 Instruction *visitXor(BinaryOperator &I);
118 Instruction *visitSetCondInst(SetCondInst &I);
119 Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
121 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
122 Instruction::BinaryOps Cond, Instruction &I);
123 Instruction *visitShiftInst(ShiftInst &I);
124 Instruction *FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
126 Instruction *visitCastInst(CastInst &CI);
127 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
129 Instruction *visitSelectInst(SelectInst &CI);
130 Instruction *visitCallInst(CallInst &CI);
131 Instruction *visitInvokeInst(InvokeInst &II);
132 Instruction *visitPHINode(PHINode &PN);
133 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
134 Instruction *visitAllocationInst(AllocationInst &AI);
135 Instruction *visitFreeInst(FreeInst &FI);
136 Instruction *visitLoadInst(LoadInst &LI);
137 Instruction *visitStoreInst(StoreInst &SI);
138 Instruction *visitBranchInst(BranchInst &BI);
139 Instruction *visitSwitchInst(SwitchInst &SI);
140 Instruction *visitExtractElementInst(ExtractElementInst &EI);
142 // visitInstruction - Specify what to return for unhandled instructions...
143 Instruction *visitInstruction(Instruction &I) { return 0; }
146 Instruction *visitCallSite(CallSite CS);
147 bool transformConstExprCastCall(CallSite CS);
150 // InsertNewInstBefore - insert an instruction New before instruction Old
151 // in the program. Add the new instruction to the worklist.
153 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
154 assert(New && New->getParent() == 0 &&
155 "New instruction already inserted into a basic block!");
156 BasicBlock *BB = Old.getParent();
157 BB->getInstList().insert(&Old, New); // Insert inst
158 WorkList.push_back(New); // Add to worklist
162 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
163 /// This also adds the cast to the worklist. Finally, this returns the
165 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
166 if (V->getType() == Ty) return V;
168 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
169 WorkList.push_back(C);
173 // ReplaceInstUsesWith - This method is to be used when an instruction is
174 // found to be dead, replacable with another preexisting expression. Here
175 // we add all uses of I to the worklist, replace all uses of I with the new
176 // value, then return I, so that the inst combiner will know that I was
179 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
180 AddUsersToWorkList(I); // Add all modified instrs to worklist
182 I.replaceAllUsesWith(V);
185 // If we are replacing the instruction with itself, this must be in a
186 // segment of unreachable code, so just clobber the instruction.
187 I.replaceAllUsesWith(UndefValue::get(I.getType()));
192 // UpdateValueUsesWith - This method is to be used when an value is
193 // found to be replacable with another preexisting expression or was
194 // updated. Here we add all uses of I to the worklist, replace all uses of
195 // I with the new value (unless the instruction was just updated), then
196 // return true, so that the inst combiner will know that I was modified.
198 bool UpdateValueUsesWith(Value *Old, Value *New) {
199 AddUsersToWorkList(*Old); // Add all modified instrs to worklist
201 Old->replaceAllUsesWith(New);
202 if (Instruction *I = dyn_cast<Instruction>(Old))
203 WorkList.push_back(I);
204 if (Instruction *I = dyn_cast<Instruction>(New))
205 WorkList.push_back(I);
209 // EraseInstFromFunction - When dealing with an instruction that has side
210 // effects or produces a void value, we can't rely on DCE to delete the
211 // instruction. Instead, visit methods should return the value returned by
213 Instruction *EraseInstFromFunction(Instruction &I) {
214 assert(I.use_empty() && "Cannot erase instruction that is used!");
215 AddUsesToWorkList(I);
216 removeFromWorkList(&I);
218 return 0; // Don't do anything with FI
222 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
223 /// InsertBefore instruction. This is specialized a bit to avoid inserting
224 /// casts that are known to not do anything...
226 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
227 Instruction *InsertBefore);
229 // SimplifyCommutative - This performs a few simplifications for commutative
231 bool SimplifyCommutative(BinaryOperator &I);
233 bool SimplifyDemandedBits(Value *V, uint64_t Mask,
234 uint64_t &KnownZero, uint64_t &KnownOne,
237 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
238 // PHI node as operand #0, see if we can fold the instruction into the PHI
239 // (which is only possible if all operands to the PHI are constants).
240 Instruction *FoldOpIntoPhi(Instruction &I);
242 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
243 // operator and they all are only used by the PHI, PHI together their
244 // inputs, and do the operation once, to the result of the PHI.
245 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
247 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
248 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
250 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask,
251 bool isSub, Instruction &I);
252 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
253 bool Inside, Instruction &IB);
254 Instruction *PromoteCastOfAllocation(CastInst &CI, AllocationInst &AI);
257 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
260 // getComplexity: Assign a complexity or rank value to LLVM Values...
261 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
262 static unsigned getComplexity(Value *V) {
263 if (isa<Instruction>(V)) {
264 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
268 if (isa<Argument>(V)) return 3;
269 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
272 // isOnlyUse - Return true if this instruction will be deleted if we stop using
274 static bool isOnlyUse(Value *V) {
275 return V->hasOneUse() || isa<Constant>(V);
278 // getPromotedType - Return the specified type promoted as it would be to pass
279 // though a va_arg area...
280 static const Type *getPromotedType(const Type *Ty) {
281 switch (Ty->getTypeID()) {
282 case Type::SByteTyID:
283 case Type::ShortTyID: return Type::IntTy;
284 case Type::UByteTyID:
285 case Type::UShortTyID: return Type::UIntTy;
286 case Type::FloatTyID: return Type::DoubleTy;
291 /// isCast - If the specified operand is a CastInst or a constant expr cast,
292 /// return the operand value, otherwise return null.
293 static Value *isCast(Value *V) {
294 if (CastInst *I = dyn_cast<CastInst>(V))
295 return I->getOperand(0);
296 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
297 if (CE->getOpcode() == Instruction::Cast)
298 return CE->getOperand(0);
302 // SimplifyCommutative - This performs a few simplifications for commutative
305 // 1. Order operands such that they are listed from right (least complex) to
306 // left (most complex). This puts constants before unary operators before
309 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
310 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
312 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
313 bool Changed = false;
314 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
315 Changed = !I.swapOperands();
317 if (!I.isAssociative()) return Changed;
318 Instruction::BinaryOps Opcode = I.getOpcode();
319 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
320 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
321 if (isa<Constant>(I.getOperand(1))) {
322 Constant *Folded = ConstantExpr::get(I.getOpcode(),
323 cast<Constant>(I.getOperand(1)),
324 cast<Constant>(Op->getOperand(1)));
325 I.setOperand(0, Op->getOperand(0));
326 I.setOperand(1, Folded);
328 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
329 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
330 isOnlyUse(Op) && isOnlyUse(Op1)) {
331 Constant *C1 = cast<Constant>(Op->getOperand(1));
332 Constant *C2 = cast<Constant>(Op1->getOperand(1));
334 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
335 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
336 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
339 WorkList.push_back(New);
340 I.setOperand(0, New);
341 I.setOperand(1, Folded);
348 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
349 // if the LHS is a constant zero (which is the 'negate' form).
351 static inline Value *dyn_castNegVal(Value *V) {
352 if (BinaryOperator::isNeg(V))
353 return BinaryOperator::getNegArgument(V);
355 // Constants can be considered to be negated values if they can be folded.
356 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
357 return ConstantExpr::getNeg(C);
361 static inline Value *dyn_castNotVal(Value *V) {
362 if (BinaryOperator::isNot(V))
363 return BinaryOperator::getNotArgument(V);
365 // Constants can be considered to be not'ed values...
366 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
367 return ConstantExpr::getNot(C);
371 // dyn_castFoldableMul - If this value is a multiply that can be folded into
372 // other computations (because it has a constant operand), return the
373 // non-constant operand of the multiply, and set CST to point to the multiplier.
374 // Otherwise, return null.
376 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
377 if (V->hasOneUse() && V->getType()->isInteger())
378 if (Instruction *I = dyn_cast<Instruction>(V)) {
379 if (I->getOpcode() == Instruction::Mul)
380 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
381 return I->getOperand(0);
382 if (I->getOpcode() == Instruction::Shl)
383 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
384 // The multiplier is really 1 << CST.
385 Constant *One = ConstantInt::get(V->getType(), 1);
386 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
387 return I->getOperand(0);
393 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
394 /// expression, return it.
395 static User *dyn_castGetElementPtr(Value *V) {
396 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
397 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
398 if (CE->getOpcode() == Instruction::GetElementPtr)
399 return cast<User>(V);
403 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
404 static ConstantInt *AddOne(ConstantInt *C) {
405 return cast<ConstantInt>(ConstantExpr::getAdd(C,
406 ConstantInt::get(C->getType(), 1)));
408 static ConstantInt *SubOne(ConstantInt *C) {
409 return cast<ConstantInt>(ConstantExpr::getSub(C,
410 ConstantInt::get(C->getType(), 1)));
413 /// GetConstantInType - Return a ConstantInt with the specified type and value.
415 static ConstantIntegral *GetConstantInType(const Type *Ty, uint64_t Val) {
416 if (Ty->isUnsigned())
417 return ConstantUInt::get(Ty, Val);
418 else if (Ty->getTypeID() == Type::BoolTyID)
419 return ConstantBool::get(Val);
421 SVal <<= 64-Ty->getPrimitiveSizeInBits();
422 SVal >>= 64-Ty->getPrimitiveSizeInBits();
423 return ConstantSInt::get(Ty, SVal);
427 /// ComputeMaskedBits - Determine which of the bits specified in Mask are
428 /// known to be either zero or one and return them in the KnownZero/KnownOne
429 /// bitsets. This code only analyzes bits in Mask, in order to short-circuit
431 static void ComputeMaskedBits(Value *V, uint64_t Mask, uint64_t &KnownZero,
432 uint64_t &KnownOne, unsigned Depth = 0) {
433 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
434 // we cannot optimize based on the assumption that it is zero without changing
435 // it to be an explicit zero. If we don't change it to zero, other code could
436 // optimized based on the contradictory assumption that it is non-zero.
437 // Because instcombine aggressively folds operations with undef args anyway,
438 // this won't lose us code quality.
439 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V)) {
440 // We know all of the bits for a constant!
441 KnownOne = CI->getZExtValue() & Mask;
442 KnownZero = ~KnownOne & Mask;
446 KnownZero = KnownOne = 0; // Don't know anything.
447 if (Depth == 6 || Mask == 0)
448 return; // Limit search depth.
450 uint64_t KnownZero2, KnownOne2;
451 Instruction *I = dyn_cast<Instruction>(V);
454 switch (I->getOpcode()) {
455 case Instruction::And:
456 // If either the LHS or the RHS are Zero, the result is zero.
457 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
459 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
460 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
461 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
463 // Output known-1 bits are only known if set in both the LHS & RHS.
464 KnownOne &= KnownOne2;
465 // Output known-0 are known to be clear if zero in either the LHS | RHS.
466 KnownZero |= KnownZero2;
468 case Instruction::Or:
469 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
471 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
472 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
473 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
475 // Output known-0 bits are only known if clear in both the LHS & RHS.
476 KnownZero &= KnownZero2;
477 // Output known-1 are known to be set if set in either the LHS | RHS.
478 KnownOne |= KnownOne2;
480 case Instruction::Xor: {
481 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
482 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
483 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
484 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
486 // Output known-0 bits are known if clear or set in both the LHS & RHS.
487 uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
488 // Output known-1 are known to be set if set in only one of the LHS, RHS.
489 KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
490 KnownZero = KnownZeroOut;
493 case Instruction::Select:
494 ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
495 ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
496 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
497 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
499 // Only known if known in both the LHS and RHS.
500 KnownOne &= KnownOne2;
501 KnownZero &= KnownZero2;
503 case Instruction::Cast: {
504 const Type *SrcTy = I->getOperand(0)->getType();
505 if (!SrcTy->isIntegral()) return;
507 // If this is an integer truncate or noop, just look in the input.
508 if (SrcTy->getPrimitiveSizeInBits() >=
509 I->getType()->getPrimitiveSizeInBits()) {
510 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
514 // Sign or Zero extension. Compute the bits in the result that are not
515 // present in the input.
516 uint64_t NotIn = ~SrcTy->getIntegralTypeMask();
517 uint64_t NewBits = I->getType()->getIntegralTypeMask() & NotIn;
519 // Handle zero extension.
520 if (!SrcTy->isSigned()) {
521 Mask &= SrcTy->getIntegralTypeMask();
522 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
523 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
524 // The top bits are known to be zero.
525 KnownZero |= NewBits;
528 Mask &= SrcTy->getIntegralTypeMask();
529 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
530 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
532 // If the sign bit of the input is known set or clear, then we know the
533 // top bits of the result.
534 uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
535 if (KnownZero & InSignBit) { // Input sign bit known zero
536 KnownZero |= NewBits;
537 KnownOne &= ~NewBits;
538 } else if (KnownOne & InSignBit) { // Input sign bit known set
540 KnownZero &= ~NewBits;
541 } else { // Input sign bit unknown
542 KnownZero &= ~NewBits;
543 KnownOne &= ~NewBits;
548 case Instruction::Shl:
549 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
550 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) {
551 Mask >>= SA->getValue();
552 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
553 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
554 KnownZero <<= SA->getValue();
555 KnownOne <<= SA->getValue();
556 KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
560 case Instruction::Shr:
561 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
562 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) {
563 // Compute the new bits that are at the top now.
564 uint64_t HighBits = (1ULL << SA->getValue())-1;
565 HighBits <<= I->getType()->getPrimitiveSizeInBits()-SA->getValue();
567 if (I->getType()->isUnsigned()) { // Unsigned shift right.
568 Mask <<= SA->getValue();
569 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1);
570 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
571 KnownZero >>= SA->getValue();
572 KnownOne >>= SA->getValue();
573 KnownZero |= HighBits; // high bits known zero.
575 Mask <<= SA->getValue();
576 ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1);
577 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
578 KnownZero >>= SA->getValue();
579 KnownOne >>= SA->getValue();
581 // Handle the sign bits.
582 uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1);
583 SignBit >>= SA->getValue(); // Adjust to where it is now in the mask.
585 if (KnownZero & SignBit) { // New bits are known zero.
586 KnownZero |= HighBits;
587 } else if (KnownOne & SignBit) { // New bits are known one.
588 KnownOne |= HighBits;
597 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
598 /// this predicate to simplify operations downstream. Mask is known to be zero
599 /// for bits that V cannot have.
600 static bool MaskedValueIsZero(Value *V, uint64_t Mask, unsigned Depth = 0) {
601 uint64_t KnownZero, KnownOne;
602 ComputeMaskedBits(V, Mask, KnownZero, KnownOne, Depth);
603 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
604 return (KnownZero & Mask) == Mask;
607 /// ShrinkDemandedConstant - Check to see if the specified operand of the
608 /// specified instruction is a constant integer. If so, check to see if there
609 /// are any bits set in the constant that are not demanded. If so, shrink the
610 /// constant and return true.
611 static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
613 ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
614 if (!OpC) return false;
616 // If there are no bits set that aren't demanded, nothing to do.
617 if ((~Demanded & OpC->getZExtValue()) == 0)
620 // This is producing any bits that are not needed, shrink the RHS.
621 uint64_t Val = Demanded & OpC->getZExtValue();
622 I->setOperand(OpNo, GetConstantInType(OpC->getType(), Val));
626 // ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
627 // set of known zero and one bits, compute the maximum and minimum values that
628 // could have the specified known zero and known one bits, returning them in
630 static void ComputeSignedMinMaxValuesFromKnownBits(const Type *Ty,
633 int64_t &Min, int64_t &Max) {
634 uint64_t TypeBits = Ty->getIntegralTypeMask();
635 uint64_t UnknownBits = ~(KnownZero|KnownOne) & TypeBits;
637 uint64_t SignBit = 1ULL << (Ty->getPrimitiveSizeInBits()-1);
639 // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
640 // bit if it is unknown.
642 Max = KnownOne|UnknownBits;
644 if (SignBit & UnknownBits) { // Sign bit is unknown
649 // Sign extend the min/max values.
650 int ShAmt = 64-Ty->getPrimitiveSizeInBits();
651 Min = (Min << ShAmt) >> ShAmt;
652 Max = (Max << ShAmt) >> ShAmt;
655 // ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
656 // a set of known zero and one bits, compute the maximum and minimum values that
657 // could have the specified known zero and known one bits, returning them in
659 static void ComputeUnsignedMinMaxValuesFromKnownBits(const Type *Ty,
664 uint64_t TypeBits = Ty->getIntegralTypeMask();
665 uint64_t UnknownBits = ~(KnownZero|KnownOne) & TypeBits;
667 // The minimum value is when the unknown bits are all zeros.
669 // The maximum value is when the unknown bits are all ones.
670 Max = KnownOne|UnknownBits;
674 /// SimplifyDemandedBits - Look at V. At this point, we know that only the
675 /// DemandedMask bits of the result of V are ever used downstream. If we can
676 /// use this information to simplify V, do so and return true. Otherwise,
677 /// analyze the expression and return a mask of KnownOne and KnownZero bits for
678 /// the expression (used to simplify the caller). The KnownZero/One bits may
679 /// only be accurate for those bits in the DemandedMask.
680 bool InstCombiner::SimplifyDemandedBits(Value *V, uint64_t DemandedMask,
681 uint64_t &KnownZero, uint64_t &KnownOne,
683 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V)) {
684 // We know all of the bits for a constant!
685 KnownOne = CI->getZExtValue() & DemandedMask;
686 KnownZero = ~KnownOne & DemandedMask;
690 KnownZero = KnownOne = 0;
691 if (!V->hasOneUse()) { // Other users may use these bits.
692 if (Depth != 0) { // Not at the root.
693 // Just compute the KnownZero/KnownOne bits to simplify things downstream.
694 ComputeMaskedBits(V, DemandedMask, KnownZero, KnownOne, Depth);
697 // If this is the root being simplified, allow it to have multiple uses,
698 // just set the DemandedMask to all bits.
699 DemandedMask = V->getType()->getIntegralTypeMask();
700 } else if (DemandedMask == 0) { // Not demanding any bits from V.
701 if (V != UndefValue::get(V->getType()))
702 return UpdateValueUsesWith(V, UndefValue::get(V->getType()));
704 } else if (Depth == 6) { // Limit search depth.
708 Instruction *I = dyn_cast<Instruction>(V);
709 if (!I) return false; // Only analyze instructions.
711 uint64_t KnownZero2, KnownOne2;
712 switch (I->getOpcode()) {
714 case Instruction::And:
715 // If either the LHS or the RHS are Zero, the result is zero.
716 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
717 KnownZero, KnownOne, Depth+1))
719 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
721 // If something is known zero on the RHS, the bits aren't demanded on the
723 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~KnownZero,
724 KnownZero2, KnownOne2, Depth+1))
726 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
728 // If all of the demanded bits are known one on one side, return the other.
729 // These bits cannot contribute to the result of the 'and'.
730 if ((DemandedMask & ~KnownZero2 & KnownOne) == (DemandedMask & ~KnownZero2))
731 return UpdateValueUsesWith(I, I->getOperand(0));
732 if ((DemandedMask & ~KnownZero & KnownOne2) == (DemandedMask & ~KnownZero))
733 return UpdateValueUsesWith(I, I->getOperand(1));
735 // If all of the demanded bits in the inputs are known zeros, return zero.
736 if ((DemandedMask & (KnownZero|KnownZero2)) == DemandedMask)
737 return UpdateValueUsesWith(I, Constant::getNullValue(I->getType()));
739 // If the RHS is a constant, see if we can simplify it.
740 if (ShrinkDemandedConstant(I, 1, DemandedMask & ~KnownZero2))
741 return UpdateValueUsesWith(I, I);
743 // Output known-1 bits are only known if set in both the LHS & RHS.
744 KnownOne &= KnownOne2;
745 // Output known-0 are known to be clear if zero in either the LHS | RHS.
746 KnownZero |= KnownZero2;
748 case Instruction::Or:
749 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
750 KnownZero, KnownOne, Depth+1))
752 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
753 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~KnownOne,
754 KnownZero2, KnownOne2, Depth+1))
756 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
758 // If all of the demanded bits are known zero on one side, return the other.
759 // These bits cannot contribute to the result of the 'or'.
760 if ((DemandedMask & ~KnownOne2 & KnownZero) == DemandedMask & ~KnownOne2)
761 return UpdateValueUsesWith(I, I->getOperand(0));
762 if ((DemandedMask & ~KnownOne & KnownZero2) == DemandedMask & ~KnownOne)
763 return UpdateValueUsesWith(I, I->getOperand(1));
765 // If all of the potentially set bits on one side are known to be set on
766 // the other side, just use the 'other' side.
767 if ((DemandedMask & (~KnownZero) & KnownOne2) ==
768 (DemandedMask & (~KnownZero)))
769 return UpdateValueUsesWith(I, I->getOperand(0));
770 if ((DemandedMask & (~KnownZero2) & KnownOne) ==
771 (DemandedMask & (~KnownZero2)))
772 return UpdateValueUsesWith(I, I->getOperand(1));
774 // If the RHS is a constant, see if we can simplify it.
775 if (ShrinkDemandedConstant(I, 1, DemandedMask))
776 return UpdateValueUsesWith(I, I);
778 // Output known-0 bits are only known if clear in both the LHS & RHS.
779 KnownZero &= KnownZero2;
780 // Output known-1 are known to be set if set in either the LHS | RHS.
781 KnownOne |= KnownOne2;
783 case Instruction::Xor: {
784 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
785 KnownZero, KnownOne, Depth+1))
787 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
788 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
789 KnownZero2, KnownOne2, Depth+1))
791 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
793 // If all of the demanded bits are known zero on one side, return the other.
794 // These bits cannot contribute to the result of the 'xor'.
795 if ((DemandedMask & KnownZero) == DemandedMask)
796 return UpdateValueUsesWith(I, I->getOperand(0));
797 if ((DemandedMask & KnownZero2) == DemandedMask)
798 return UpdateValueUsesWith(I, I->getOperand(1));
800 // Output known-0 bits are known if clear or set in both the LHS & RHS.
801 uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
802 // Output known-1 are known to be set if set in only one of the LHS, RHS.
803 uint64_t KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
805 // If all of the unknown bits are known to be zero on one side or the other
806 // (but not both) turn this into an *inclusive* or.
807 // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
808 if (uint64_t UnknownBits = DemandedMask & ~(KnownZeroOut|KnownOneOut)) {
809 if ((UnknownBits & (KnownZero|KnownZero2)) == UnknownBits) {
811 BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
813 InsertNewInstBefore(Or, *I);
814 return UpdateValueUsesWith(I, Or);
818 // If all of the demanded bits on one side are known, and all of the set
819 // bits on that side are also known to be set on the other side, turn this
820 // into an AND, as we know the bits will be cleared.
821 // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
822 if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask) { // all known
823 if ((KnownOne & KnownOne2) == KnownOne) {
824 Constant *AndC = GetConstantInType(I->getType(),
825 ~KnownOne & DemandedMask);
827 BinaryOperator::createAnd(I->getOperand(0), AndC, "tmp");
828 InsertNewInstBefore(And, *I);
829 return UpdateValueUsesWith(I, And);
833 // If the RHS is a constant, see if we can simplify it.
834 // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
835 if (ShrinkDemandedConstant(I, 1, DemandedMask))
836 return UpdateValueUsesWith(I, I);
838 KnownZero = KnownZeroOut;
839 KnownOne = KnownOneOut;
842 case Instruction::Select:
843 if (SimplifyDemandedBits(I->getOperand(2), DemandedMask,
844 KnownZero, KnownOne, Depth+1))
846 if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
847 KnownZero2, KnownOne2, Depth+1))
849 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
850 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
852 // If the operands are constants, see if we can simplify them.
853 if (ShrinkDemandedConstant(I, 1, DemandedMask))
854 return UpdateValueUsesWith(I, I);
855 if (ShrinkDemandedConstant(I, 2, DemandedMask))
856 return UpdateValueUsesWith(I, I);
858 // Only known if known in both the LHS and RHS.
859 KnownOne &= KnownOne2;
860 KnownZero &= KnownZero2;
862 case Instruction::Cast: {
863 const Type *SrcTy = I->getOperand(0)->getType();
864 if (!SrcTy->isIntegral()) return false;
866 // If this is an integer truncate or noop, just look in the input.
867 if (SrcTy->getPrimitiveSizeInBits() >=
868 I->getType()->getPrimitiveSizeInBits()) {
869 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
870 KnownZero, KnownOne, Depth+1))
872 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
876 // Sign or Zero extension. Compute the bits in the result that are not
877 // present in the input.
878 uint64_t NotIn = ~SrcTy->getIntegralTypeMask();
879 uint64_t NewBits = I->getType()->getIntegralTypeMask() & NotIn;
881 // Handle zero extension.
882 if (!SrcTy->isSigned()) {
883 DemandedMask &= SrcTy->getIntegralTypeMask();
884 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
885 KnownZero, KnownOne, Depth+1))
887 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
888 // The top bits are known to be zero.
889 KnownZero |= NewBits;
892 uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
893 int64_t InputDemandedBits = DemandedMask & SrcTy->getIntegralTypeMask();
895 // If any of the sign extended bits are demanded, we know that the sign
897 if (NewBits & DemandedMask)
898 InputDemandedBits |= InSignBit;
900 if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits,
901 KnownZero, KnownOne, Depth+1))
903 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
905 // If the sign bit of the input is known set or clear, then we know the
906 // top bits of the result.
908 // If the input sign bit is known zero, or if the NewBits are not demanded
909 // convert this into a zero extension.
910 if ((KnownZero & InSignBit) || (NewBits & ~DemandedMask) == NewBits) {
911 // Convert to unsigned first.
913 NewVal = new CastInst(I->getOperand(0), SrcTy->getUnsignedVersion(),
914 I->getOperand(0)->getName());
915 InsertNewInstBefore(NewVal, *I);
916 // Then cast that to the destination type.
917 NewVal = new CastInst(NewVal, I->getType(), I->getName());
918 InsertNewInstBefore(NewVal, *I);
919 return UpdateValueUsesWith(I, NewVal);
920 } else if (KnownOne & InSignBit) { // Input sign bit known set
922 KnownZero &= ~NewBits;
923 } else { // Input sign bit unknown
924 KnownZero &= ~NewBits;
925 KnownOne &= ~NewBits;
930 case Instruction::Shl:
931 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) {
932 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask >> SA->getValue(),
933 KnownZero, KnownOne, Depth+1))
935 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
936 KnownZero <<= SA->getValue();
937 KnownOne <<= SA->getValue();
938 KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
941 case Instruction::Shr:
942 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) {
943 unsigned ShAmt = SA->getValue();
945 // Compute the new bits that are at the top now.
946 uint64_t HighBits = (1ULL << ShAmt)-1;
947 HighBits <<= I->getType()->getPrimitiveSizeInBits() - ShAmt;
948 uint64_t TypeMask = I->getType()->getIntegralTypeMask();
949 if (I->getType()->isUnsigned()) { // Unsigned shift right.
950 if (SimplifyDemandedBits(I->getOperand(0),
951 (DemandedMask << ShAmt) & TypeMask,
952 KnownZero, KnownOne, Depth+1))
954 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
955 KnownZero &= TypeMask;
956 KnownOne &= TypeMask;
959 KnownZero |= HighBits; // high bits known zero.
960 } else { // Signed shift right.
961 if (SimplifyDemandedBits(I->getOperand(0),
962 (DemandedMask << ShAmt) & TypeMask,
963 KnownZero, KnownOne, Depth+1))
965 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
966 KnownZero &= TypeMask;
967 KnownOne &= TypeMask;
968 KnownZero >>= SA->getValue();
969 KnownOne >>= SA->getValue();
971 // Handle the sign bits.
972 uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1);
973 SignBit >>= SA->getValue(); // Adjust to where it is now in the mask.
975 // If the input sign bit is known to be zero, or if none of the top bits
976 // are demanded, turn this into an unsigned shift right.
977 if ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) {
978 // Convert the input to unsigned.
980 NewVal = new CastInst(I->getOperand(0),
981 I->getType()->getUnsignedVersion(),
982 I->getOperand(0)->getName());
983 InsertNewInstBefore(NewVal, *I);
984 // Perform the unsigned shift right.
985 NewVal = new ShiftInst(Instruction::Shr, NewVal, SA, I->getName());
986 InsertNewInstBefore(NewVal, *I);
987 // Then cast that to the destination type.
988 NewVal = new CastInst(NewVal, I->getType(), I->getName());
989 InsertNewInstBefore(NewVal, *I);
990 return UpdateValueUsesWith(I, NewVal);
991 } else if (KnownOne & SignBit) { // New bits are known one.
992 KnownOne |= HighBits;
999 // If the client is only demanding bits that we know, return the known
1001 if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask)
1002 return UpdateValueUsesWith(I, GetConstantInType(I->getType(), KnownOne));
1006 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
1007 // true when both operands are equal...
1009 static bool isTrueWhenEqual(Instruction &I) {
1010 return I.getOpcode() == Instruction::SetEQ ||
1011 I.getOpcode() == Instruction::SetGE ||
1012 I.getOpcode() == Instruction::SetLE;
1015 /// AssociativeOpt - Perform an optimization on an associative operator. This
1016 /// function is designed to check a chain of associative operators for a
1017 /// potential to apply a certain optimization. Since the optimization may be
1018 /// applicable if the expression was reassociated, this checks the chain, then
1019 /// reassociates the expression as necessary to expose the optimization
1020 /// opportunity. This makes use of a special Functor, which must define
1021 /// 'shouldApply' and 'apply' methods.
1023 template<typename Functor>
1024 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
1025 unsigned Opcode = Root.getOpcode();
1026 Value *LHS = Root.getOperand(0);
1028 // Quick check, see if the immediate LHS matches...
1029 if (F.shouldApply(LHS))
1030 return F.apply(Root);
1032 // Otherwise, if the LHS is not of the same opcode as the root, return.
1033 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1034 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
1035 // Should we apply this transform to the RHS?
1036 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
1038 // If not to the RHS, check to see if we should apply to the LHS...
1039 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
1040 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
1044 // If the functor wants to apply the optimization to the RHS of LHSI,
1045 // reassociate the expression from ((? op A) op B) to (? op (A op B))
1047 BasicBlock *BB = Root.getParent();
1049 // Now all of the instructions are in the current basic block, go ahead
1050 // and perform the reassociation.
1051 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
1053 // First move the selected RHS to the LHS of the root...
1054 Root.setOperand(0, LHSI->getOperand(1));
1056 // Make what used to be the LHS of the root be the user of the root...
1057 Value *ExtraOperand = TmpLHSI->getOperand(1);
1058 if (&Root == TmpLHSI) {
1059 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
1062 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
1063 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
1064 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
1065 BasicBlock::iterator ARI = &Root; ++ARI;
1066 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
1069 // Now propagate the ExtraOperand down the chain of instructions until we
1071 while (TmpLHSI != LHSI) {
1072 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
1073 // Move the instruction to immediately before the chain we are
1074 // constructing to avoid breaking dominance properties.
1075 NextLHSI->getParent()->getInstList().remove(NextLHSI);
1076 BB->getInstList().insert(ARI, NextLHSI);
1079 Value *NextOp = NextLHSI->getOperand(1);
1080 NextLHSI->setOperand(1, ExtraOperand);
1082 ExtraOperand = NextOp;
1085 // Now that the instructions are reassociated, have the functor perform
1086 // the transformation...
1087 return F.apply(Root);
1090 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
1096 // AddRHS - Implements: X + X --> X << 1
1099 AddRHS(Value *rhs) : RHS(rhs) {}
1100 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1101 Instruction *apply(BinaryOperator &Add) const {
1102 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
1103 ConstantInt::get(Type::UByteTy, 1));
1107 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
1109 struct AddMaskingAnd {
1111 AddMaskingAnd(Constant *c) : C2(c) {}
1112 bool shouldApply(Value *LHS) const {
1114 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
1115 ConstantExpr::getAnd(C1, C2)->isNullValue();
1117 Instruction *apply(BinaryOperator &Add) const {
1118 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
1122 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
1124 if (isa<CastInst>(I)) {
1125 if (Constant *SOC = dyn_cast<Constant>(SO))
1126 return ConstantExpr::getCast(SOC, I.getType());
1128 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
1129 SO->getName() + ".cast"), I);
1132 // Figure out if the constant is the left or the right argument.
1133 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
1134 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
1136 if (Constant *SOC = dyn_cast<Constant>(SO)) {
1138 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
1139 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
1142 Value *Op0 = SO, *Op1 = ConstOperand;
1144 std::swap(Op0, Op1);
1146 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
1147 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
1148 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
1149 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
1151 assert(0 && "Unknown binary instruction type!");
1154 return IC->InsertNewInstBefore(New, I);
1157 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
1158 // constant as the other operand, try to fold the binary operator into the
1159 // select arguments. This also works for Cast instructions, which obviously do
1160 // not have a second operand.
1161 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
1163 // Don't modify shared select instructions
1164 if (!SI->hasOneUse()) return 0;
1165 Value *TV = SI->getOperand(1);
1166 Value *FV = SI->getOperand(2);
1168 if (isa<Constant>(TV) || isa<Constant>(FV)) {
1169 // Bool selects with constant operands can be folded to logical ops.
1170 if (SI->getType() == Type::BoolTy) return 0;
1172 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
1173 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
1175 return new SelectInst(SI->getCondition(), SelectTrueVal,
1182 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
1183 /// node as operand #0, see if we can fold the instruction into the PHI (which
1184 /// is only possible if all operands to the PHI are constants).
1185 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
1186 PHINode *PN = cast<PHINode>(I.getOperand(0));
1187 unsigned NumPHIValues = PN->getNumIncomingValues();
1188 if (!PN->hasOneUse() || NumPHIValues == 0 ||
1189 !isa<Constant>(PN->getIncomingValue(0))) return 0;
1191 // Check to see if all of the operands of the PHI are constants. If not, we
1192 // cannot do the transformation.
1193 for (unsigned i = 1; i != NumPHIValues; ++i)
1194 if (!isa<Constant>(PN->getIncomingValue(i)))
1197 // Okay, we can do the transformation: create the new PHI node.
1198 PHINode *NewPN = new PHINode(I.getType(), I.getName());
1200 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
1201 InsertNewInstBefore(NewPN, *PN);
1203 // Next, add all of the operands to the PHI.
1204 if (I.getNumOperands() == 2) {
1205 Constant *C = cast<Constant>(I.getOperand(1));
1206 for (unsigned i = 0; i != NumPHIValues; ++i) {
1207 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
1208 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
1209 PN->getIncomingBlock(i));
1212 assert(isa<CastInst>(I) && "Unary op should be a cast!");
1213 const Type *RetTy = I.getType();
1214 for (unsigned i = 0; i != NumPHIValues; ++i) {
1215 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
1216 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
1217 PN->getIncomingBlock(i));
1220 return ReplaceInstUsesWith(I, NewPN);
1223 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
1224 bool Changed = SimplifyCommutative(I);
1225 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1227 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1228 // X + undef -> undef
1229 if (isa<UndefValue>(RHS))
1230 return ReplaceInstUsesWith(I, RHS);
1233 if (!I.getType()->isFloatingPoint()) { // NOTE: -0 + +0 = +0.
1234 if (RHSC->isNullValue())
1235 return ReplaceInstUsesWith(I, LHS);
1236 } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1237 if (CFP->isExactlyValue(-0.0))
1238 return ReplaceInstUsesWith(I, LHS);
1241 // X + (signbit) --> X ^ signbit
1242 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
1243 uint64_t Val = CI->getZExtValue();
1244 if (Val == (1ULL << (CI->getType()->getPrimitiveSizeInBits()-1)))
1245 return BinaryOperator::createXor(LHS, RHS);
1248 if (isa<PHINode>(LHS))
1249 if (Instruction *NV = FoldOpIntoPhi(I))
1252 ConstantInt *XorRHS = 0;
1254 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
1255 unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
1256 int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
1257 uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
1259 uint64_t C0080Val = 1ULL << 31;
1260 int64_t CFF80Val = -C0080Val;
1263 if (TySizeBits > Size) {
1265 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
1266 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
1267 if (RHSSExt == CFF80Val) {
1268 if (XorRHS->getZExtValue() == C0080Val)
1270 } else if (RHSZExt == C0080Val) {
1271 if (XorRHS->getSExtValue() == CFF80Val)
1275 // This is a sign extend if the top bits are known zero.
1276 uint64_t Mask = ~0ULL;
1277 Mask <<= 64-(TySizeBits-Size);
1278 Mask &= XorLHS->getType()->getIntegralTypeMask();
1279 if (!MaskedValueIsZero(XorLHS, Mask))
1280 Size = 0; // Not a sign ext, but can't be any others either.
1287 } while (Size >= 8);
1290 const Type *MiddleType = 0;
1293 case 32: MiddleType = Type::IntTy; break;
1294 case 16: MiddleType = Type::ShortTy; break;
1295 case 8: MiddleType = Type::SByteTy; break;
1298 Instruction *NewTrunc = new CastInst(XorLHS, MiddleType, "sext");
1299 InsertNewInstBefore(NewTrunc, I);
1300 return new CastInst(NewTrunc, I.getType());
1306 if (I.getType()->isInteger()) {
1307 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
1309 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
1310 if (RHSI->getOpcode() == Instruction::Sub)
1311 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
1312 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
1314 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
1315 if (LHSI->getOpcode() == Instruction::Sub)
1316 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
1317 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
1322 if (Value *V = dyn_castNegVal(LHS))
1323 return BinaryOperator::createSub(RHS, V);
1326 if (!isa<Constant>(RHS))
1327 if (Value *V = dyn_castNegVal(RHS))
1328 return BinaryOperator::createSub(LHS, V);
1332 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
1333 if (X == RHS) // X*C + X --> X * (C+1)
1334 return BinaryOperator::createMul(RHS, AddOne(C2));
1336 // X*C1 + X*C2 --> X * (C1+C2)
1338 if (X == dyn_castFoldableMul(RHS, C1))
1339 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
1342 // X + X*C --> X * (C+1)
1343 if (dyn_castFoldableMul(RHS, C2) == LHS)
1344 return BinaryOperator::createMul(LHS, AddOne(C2));
1347 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
1348 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
1349 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
1351 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
1353 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
1354 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
1355 return BinaryOperator::createSub(C, X);
1358 // (X & FF00) + xx00 -> (X+xx00) & FF00
1359 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
1360 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
1361 if (Anded == CRHS) {
1362 // See if all bits from the first bit set in the Add RHS up are included
1363 // in the mask. First, get the rightmost bit.
1364 uint64_t AddRHSV = CRHS->getRawValue();
1366 // Form a mask of all bits from the lowest bit added through the top.
1367 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
1368 AddRHSHighBits &= C2->getType()->getIntegralTypeMask();
1370 // See if the and mask includes all of these bits.
1371 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
1373 if (AddRHSHighBits == AddRHSHighBitsAnd) {
1374 // Okay, the xform is safe. Insert the new add pronto.
1375 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
1376 LHS->getName()), I);
1377 return BinaryOperator::createAnd(NewAdd, C2);
1382 // Try to fold constant add into select arguments.
1383 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
1384 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1388 return Changed ? &I : 0;
1391 // isSignBit - Return true if the value represented by the constant only has the
1392 // highest order bit set.
1393 static bool isSignBit(ConstantInt *CI) {
1394 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
1395 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
1398 /// RemoveNoopCast - Strip off nonconverting casts from the value.
1400 static Value *RemoveNoopCast(Value *V) {
1401 if (CastInst *CI = dyn_cast<CastInst>(V)) {
1402 const Type *CTy = CI->getType();
1403 const Type *OpTy = CI->getOperand(0)->getType();
1404 if (CTy->isInteger() && OpTy->isInteger()) {
1405 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
1406 return RemoveNoopCast(CI->getOperand(0));
1407 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
1408 return RemoveNoopCast(CI->getOperand(0));
1413 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
1414 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1416 if (Op0 == Op1) // sub X, X -> 0
1417 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1419 // If this is a 'B = x-(-A)', change to B = x+A...
1420 if (Value *V = dyn_castNegVal(Op1))
1421 return BinaryOperator::createAdd(Op0, V);
1423 if (isa<UndefValue>(Op0))
1424 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
1425 if (isa<UndefValue>(Op1))
1426 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
1428 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
1429 // Replace (-1 - A) with (~A)...
1430 if (C->isAllOnesValue())
1431 return BinaryOperator::createNot(Op1);
1433 // C - ~X == X + (1+C)
1435 if (match(Op1, m_Not(m_Value(X))))
1436 return BinaryOperator::createAdd(X,
1437 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
1438 // -((uint)X >> 31) -> ((int)X >> 31)
1439 // -((int)X >> 31) -> ((uint)X >> 31)
1440 if (C->isNullValue()) {
1441 Value *NoopCastedRHS = RemoveNoopCast(Op1);
1442 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
1443 if (SI->getOpcode() == Instruction::Shr)
1444 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
1446 if (SI->getType()->isSigned())
1447 NewTy = SI->getType()->getUnsignedVersion();
1449 NewTy = SI->getType()->getSignedVersion();
1450 // Check to see if we are shifting out everything but the sign bit.
1451 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
1452 // Ok, the transformation is safe. Insert a cast of the incoming
1453 // value, then the new shift, then the new cast.
1454 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
1455 SI->getOperand(0)->getName());
1456 Value *InV = InsertNewInstBefore(FirstCast, I);
1457 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
1459 if (NewShift->getType() == I.getType())
1462 InV = InsertNewInstBefore(NewShift, I);
1463 return new CastInst(NewShift, I.getType());
1469 // Try to fold constant sub into select arguments.
1470 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1471 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1474 if (isa<PHINode>(Op0))
1475 if (Instruction *NV = FoldOpIntoPhi(I))
1479 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
1480 if (Op1I->getOpcode() == Instruction::Add &&
1481 !Op0->getType()->isFloatingPoint()) {
1482 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
1483 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
1484 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
1485 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
1486 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
1487 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
1488 // C1-(X+C2) --> (C1-C2)-X
1489 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
1490 Op1I->getOperand(0));
1494 if (Op1I->hasOneUse()) {
1495 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
1496 // is not used by anyone else...
1498 if (Op1I->getOpcode() == Instruction::Sub &&
1499 !Op1I->getType()->isFloatingPoint()) {
1500 // Swap the two operands of the subexpr...
1501 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
1502 Op1I->setOperand(0, IIOp1);
1503 Op1I->setOperand(1, IIOp0);
1505 // Create the new top level add instruction...
1506 return BinaryOperator::createAdd(Op0, Op1);
1509 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
1511 if (Op1I->getOpcode() == Instruction::And &&
1512 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
1513 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
1516 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
1517 return BinaryOperator::createAnd(Op0, NewNot);
1520 // -(X sdiv C) -> (X sdiv -C)
1521 if (Op1I->getOpcode() == Instruction::Div)
1522 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
1523 if (CSI->isNullValue())
1524 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
1525 return BinaryOperator::createDiv(Op1I->getOperand(0),
1526 ConstantExpr::getNeg(DivRHS));
1528 // X - X*C --> X * (1-C)
1529 ConstantInt *C2 = 0;
1530 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
1532 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
1533 return BinaryOperator::createMul(Op0, CP1);
1538 if (!Op0->getType()->isFloatingPoint())
1539 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
1540 if (Op0I->getOpcode() == Instruction::Add) {
1541 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
1542 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1543 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
1544 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1545 } else if (Op0I->getOpcode() == Instruction::Sub) {
1546 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
1547 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
1551 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1552 if (X == Op1) { // X*C - X --> X * (C-1)
1553 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
1554 return BinaryOperator::createMul(Op1, CP1);
1557 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1558 if (X == dyn_castFoldableMul(Op1, C2))
1559 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
1564 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
1565 /// really just returns true if the most significant (sign) bit is set.
1566 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
1567 if (RHS->getType()->isSigned()) {
1568 // True if source is LHS < 0 or LHS <= -1
1569 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
1570 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
1572 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
1573 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
1574 // the size of the integer type.
1575 if (Opcode == Instruction::SetGE)
1576 return RHSC->getValue() ==
1577 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
1578 if (Opcode == Instruction::SetGT)
1579 return RHSC->getValue() ==
1580 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
1585 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
1586 bool Changed = SimplifyCommutative(I);
1587 Value *Op0 = I.getOperand(0);
1589 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
1590 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1592 // Simplify mul instructions with a constant RHS...
1593 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
1594 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1596 // ((X << C1)*C2) == (X * (C2 << C1))
1597 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
1598 if (SI->getOpcode() == Instruction::Shl)
1599 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
1600 return BinaryOperator::createMul(SI->getOperand(0),
1601 ConstantExpr::getShl(CI, ShOp));
1603 if (CI->isNullValue())
1604 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
1605 if (CI->equalsInt(1)) // X * 1 == X
1606 return ReplaceInstUsesWith(I, Op0);
1607 if (CI->isAllOnesValue()) // X * -1 == 0 - X
1608 return BinaryOperator::createNeg(Op0, I.getName());
1610 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
1611 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
1612 uint64_t C = Log2_64(Val);
1613 return new ShiftInst(Instruction::Shl, Op0,
1614 ConstantUInt::get(Type::UByteTy, C));
1616 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
1617 if (Op1F->isNullValue())
1618 return ReplaceInstUsesWith(I, Op1);
1620 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
1621 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
1622 if (Op1F->getValue() == 1.0)
1623 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
1626 // Try to fold constant mul into select arguments.
1627 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1628 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1631 if (isa<PHINode>(Op0))
1632 if (Instruction *NV = FoldOpIntoPhi(I))
1636 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
1637 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
1638 return BinaryOperator::createMul(Op0v, Op1v);
1640 // If one of the operands of the multiply is a cast from a boolean value, then
1641 // we know the bool is either zero or one, so this is a 'masking' multiply.
1642 // See if we can simplify things based on how the boolean was originally
1644 CastInst *BoolCast = 0;
1645 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
1646 if (CI->getOperand(0)->getType() == Type::BoolTy)
1649 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
1650 if (CI->getOperand(0)->getType() == Type::BoolTy)
1653 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
1654 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
1655 const Type *SCOpTy = SCIOp0->getType();
1657 // If the setcc is true iff the sign bit of X is set, then convert this
1658 // multiply into a shift/and combination.
1659 if (isa<ConstantInt>(SCIOp1) &&
1660 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
1661 // Shift the X value right to turn it into "all signbits".
1662 Constant *Amt = ConstantUInt::get(Type::UByteTy,
1663 SCOpTy->getPrimitiveSizeInBits()-1);
1664 if (SCIOp0->getType()->isUnsigned()) {
1665 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
1666 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
1667 SCIOp0->getName()), I);
1671 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
1672 BoolCast->getOperand(0)->getName()+
1675 // If the multiply type is not the same as the source type, sign extend
1676 // or truncate to the multiply type.
1677 if (I.getType() != V->getType())
1678 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1680 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1681 return BinaryOperator::createAnd(V, OtherOp);
1686 return Changed ? &I : 0;
1689 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1690 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1692 if (isa<UndefValue>(Op0)) // undef / X -> 0
1693 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1694 if (isa<UndefValue>(Op1))
1695 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1697 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1699 if (RHS->equalsInt(1))
1700 return ReplaceInstUsesWith(I, Op0);
1703 if (RHS->isAllOnesValue())
1704 return BinaryOperator::createNeg(Op0);
1706 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1707 if (LHS->getOpcode() == Instruction::Div)
1708 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1709 // (X / C1) / C2 -> X / (C1*C2)
1710 return BinaryOperator::createDiv(LHS->getOperand(0),
1711 ConstantExpr::getMul(RHS, LHSRHS));
1714 // Check to see if this is an unsigned division with an exact power of 2,
1715 // if so, convert to a right shift.
1716 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1717 if (uint64_t Val = C->getValue()) // Don't break X / 0
1718 if (isPowerOf2_64(Val)) {
1719 uint64_t C = Log2_64(Val);
1720 return new ShiftInst(Instruction::Shr, Op0,
1721 ConstantUInt::get(Type::UByteTy, C));
1725 if (RHS->getType()->isSigned())
1726 if (Value *LHSNeg = dyn_castNegVal(Op0))
1727 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1729 if (!RHS->isNullValue()) {
1730 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1731 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1733 if (isa<PHINode>(Op0))
1734 if (Instruction *NV = FoldOpIntoPhi(I))
1739 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1740 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1741 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1742 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1743 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1744 if (STO->getValue() == 0) { // Couldn't be this argument.
1745 I.setOperand(1, SFO);
1747 } else if (SFO->getValue() == 0) {
1748 I.setOperand(1, STO);
1752 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1753 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1754 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1755 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1756 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1757 TC, SI->getName()+".t");
1758 TSI = InsertNewInstBefore(TSI, I);
1760 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1761 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1762 FC, SI->getName()+".f");
1763 FSI = InsertNewInstBefore(FSI, I);
1764 return new SelectInst(SI->getOperand(0), TSI, FSI);
1768 // 0 / X == 0, we don't need to preserve faults!
1769 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1770 if (LHS->equalsInt(0))
1771 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1773 if (I.getType()->isSigned()) {
1774 // If the sign bits of both operands are zero (i.e. we can prove they are
1775 // unsigned inputs), turn this into a udiv.
1776 uint64_t Mask = 1ULL << (I.getType()->getPrimitiveSizeInBits()-1);
1777 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
1778 const Type *NTy = Op0->getType()->getUnsignedVersion();
1779 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1780 InsertNewInstBefore(LHS, I);
1782 if (Constant *R = dyn_cast<Constant>(Op1))
1783 RHS = ConstantExpr::getCast(R, NTy);
1785 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1786 Instruction *Div = BinaryOperator::createDiv(LHS, RHS, I.getName());
1787 InsertNewInstBefore(Div, I);
1788 return new CastInst(Div, I.getType());
1791 // Known to be an unsigned division.
1792 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
1793 // Turn A / (C1 << N), where C1 is "1<<C2" into A >> (N+C2) [udiv only].
1794 if (RHSI->getOpcode() == Instruction::Shl &&
1795 isa<ConstantUInt>(RHSI->getOperand(0))) {
1796 unsigned C1 = cast<ConstantUInt>(RHSI->getOperand(0))->getRawValue();
1797 if (isPowerOf2_64(C1)) {
1798 unsigned C2 = Log2_64(C1);
1799 Value *Add = RHSI->getOperand(1);
1801 Constant *C2V = ConstantUInt::get(Add->getType(), C2);
1802 Add = InsertNewInstBefore(BinaryOperator::createAdd(Add, C2V,
1805 return new ShiftInst(Instruction::Shr, Op0, Add);
1815 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1816 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1817 if (I.getType()->isSigned()) {
1818 if (Value *RHSNeg = dyn_castNegVal(Op1))
1819 if (!isa<ConstantSInt>(RHSNeg) ||
1820 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1822 AddUsesToWorkList(I);
1823 I.setOperand(1, RHSNeg);
1827 // If the top bits of both operands are zero (i.e. we can prove they are
1828 // unsigned inputs), turn this into a urem.
1829 uint64_t Mask = 1ULL << (I.getType()->getPrimitiveSizeInBits()-1);
1830 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
1831 const Type *NTy = Op0->getType()->getUnsignedVersion();
1832 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1833 InsertNewInstBefore(LHS, I);
1835 if (Constant *R = dyn_cast<Constant>(Op1))
1836 RHS = ConstantExpr::getCast(R, NTy);
1838 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1839 Instruction *Rem = BinaryOperator::createRem(LHS, RHS, I.getName());
1840 InsertNewInstBefore(Rem, I);
1841 return new CastInst(Rem, I.getType());
1845 if (isa<UndefValue>(Op0)) // undef % X -> 0
1846 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1847 if (isa<UndefValue>(Op1))
1848 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1850 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1851 if (RHS->equalsInt(1)) // X % 1 == 0
1852 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1854 // Check to see if this is an unsigned remainder with an exact power of 2,
1855 // if so, convert to a bitwise and.
1856 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1857 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1858 if (!(Val & (Val-1))) // Power of 2
1859 return BinaryOperator::createAnd(Op0,
1860 ConstantUInt::get(I.getType(), Val-1));
1862 if (!RHS->isNullValue()) {
1863 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1864 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1866 if (isa<PHINode>(Op0))
1867 if (Instruction *NV = FoldOpIntoPhi(I))
1872 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1873 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1874 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1875 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1876 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1877 if (STO->getValue() == 0) { // Couldn't be this argument.
1878 I.setOperand(1, SFO);
1880 } else if (SFO->getValue() == 0) {
1881 I.setOperand(1, STO);
1885 if (!(STO->getValue() & (STO->getValue()-1)) &&
1886 !(SFO->getValue() & (SFO->getValue()-1))) {
1887 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1888 SubOne(STO), SI->getName()+".t"), I);
1889 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1890 SubOne(SFO), SI->getName()+".f"), I);
1891 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1895 // 0 % X == 0, we don't need to preserve faults!
1896 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1897 if (LHS->equalsInt(0))
1898 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1901 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
1902 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) [urem only].
1903 if (I.getType()->isUnsigned() &&
1904 RHSI->getOpcode() == Instruction::Shl &&
1905 isa<ConstantUInt>(RHSI->getOperand(0))) {
1906 unsigned C1 = cast<ConstantUInt>(RHSI->getOperand(0))->getRawValue();
1907 if (isPowerOf2_64(C1)) {
1908 Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
1909 Value *Add = InsertNewInstBefore(BinaryOperator::createAdd(RHSI, N1,
1911 return BinaryOperator::createAnd(Op0, Add);
1919 // isMaxValueMinusOne - return true if this is Max-1
1920 static bool isMaxValueMinusOne(const ConstantInt *C) {
1921 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1922 return CU->getValue() == C->getType()->getIntegralTypeMask()-1;
1924 const ConstantSInt *CS = cast<ConstantSInt>(C);
1926 // Calculate 0111111111..11111
1927 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1928 int64_t Val = INT64_MAX; // All ones
1929 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1930 return CS->getValue() == Val-1;
1933 // isMinValuePlusOne - return true if this is Min+1
1934 static bool isMinValuePlusOne(const ConstantInt *C) {
1935 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1936 return CU->getValue() == 1;
1938 const ConstantSInt *CS = cast<ConstantSInt>(C);
1940 // Calculate 1111111111000000000000
1941 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1942 int64_t Val = -1; // All ones
1943 Val <<= TypeBits-1; // Shift over to the right spot
1944 return CS->getValue() == Val+1;
1947 // isOneBitSet - Return true if there is exactly one bit set in the specified
1949 static bool isOneBitSet(const ConstantInt *CI) {
1950 uint64_t V = CI->getRawValue();
1951 return V && (V & (V-1)) == 0;
1954 #if 0 // Currently unused
1955 // isLowOnes - Return true if the constant is of the form 0+1+.
1956 static bool isLowOnes(const ConstantInt *CI) {
1957 uint64_t V = CI->getRawValue();
1959 // There won't be bits set in parts that the type doesn't contain.
1960 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1962 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1963 return U && V && (U & V) == 0;
1967 // isHighOnes - Return true if the constant is of the form 1+0+.
1968 // This is the same as lowones(~X).
1969 static bool isHighOnes(const ConstantInt *CI) {
1970 uint64_t V = ~CI->getRawValue();
1971 if (~V == 0) return false; // 0's does not match "1+"
1973 // There won't be bits set in parts that the type doesn't contain.
1974 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1976 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1977 return U && V && (U & V) == 0;
1981 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1982 /// are carefully arranged to allow folding of expressions such as:
1984 /// (A < B) | (A > B) --> (A != B)
1986 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1987 /// represents that the comparison is true if A == B, and bit value '1' is true
1990 static unsigned getSetCondCode(const SetCondInst *SCI) {
1991 switch (SCI->getOpcode()) {
1993 case Instruction::SetGT: return 1;
1994 case Instruction::SetEQ: return 2;
1995 case Instruction::SetGE: return 3;
1996 case Instruction::SetLT: return 4;
1997 case Instruction::SetNE: return 5;
1998 case Instruction::SetLE: return 6;
2001 assert(0 && "Invalid SetCC opcode!");
2006 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
2007 /// opcode and two operands into either a constant true or false, or a brand new
2008 /// SetCC instruction.
2009 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
2011 case 0: return ConstantBool::False;
2012 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
2013 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
2014 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
2015 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
2016 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
2017 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
2018 case 7: return ConstantBool::True;
2019 default: assert(0 && "Illegal SetCCCode!"); return 0;
2023 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
2024 struct FoldSetCCLogical {
2027 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
2028 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
2029 bool shouldApply(Value *V) const {
2030 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
2031 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
2032 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
2035 Instruction *apply(BinaryOperator &Log) const {
2036 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
2037 if (SCI->getOperand(0) != LHS) {
2038 assert(SCI->getOperand(1) == LHS);
2039 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
2042 unsigned LHSCode = getSetCondCode(SCI);
2043 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
2045 switch (Log.getOpcode()) {
2046 case Instruction::And: Code = LHSCode & RHSCode; break;
2047 case Instruction::Or: Code = LHSCode | RHSCode; break;
2048 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
2049 default: assert(0 && "Illegal logical opcode!"); return 0;
2052 Value *RV = getSetCCValue(Code, LHS, RHS);
2053 if (Instruction *I = dyn_cast<Instruction>(RV))
2055 // Otherwise, it's a constant boolean value...
2056 return IC.ReplaceInstUsesWith(Log, RV);
2060 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
2061 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
2062 // guaranteed to be either a shift instruction or a binary operator.
2063 Instruction *InstCombiner::OptAndOp(Instruction *Op,
2064 ConstantIntegral *OpRHS,
2065 ConstantIntegral *AndRHS,
2066 BinaryOperator &TheAnd) {
2067 Value *X = Op->getOperand(0);
2068 Constant *Together = 0;
2069 if (!isa<ShiftInst>(Op))
2070 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
2072 switch (Op->getOpcode()) {
2073 case Instruction::Xor:
2074 if (Op->hasOneUse()) {
2075 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
2076 std::string OpName = Op->getName(); Op->setName("");
2077 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
2078 InsertNewInstBefore(And, TheAnd);
2079 return BinaryOperator::createXor(And, Together);
2082 case Instruction::Or:
2083 if (Together == AndRHS) // (X | C) & C --> C
2084 return ReplaceInstUsesWith(TheAnd, AndRHS);
2086 if (Op->hasOneUse() && Together != OpRHS) {
2087 // (X | C1) & C2 --> (X | (C1&C2)) & C2
2088 std::string Op0Name = Op->getName(); Op->setName("");
2089 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
2090 InsertNewInstBefore(Or, TheAnd);
2091 return BinaryOperator::createAnd(Or, AndRHS);
2094 case Instruction::Add:
2095 if (Op->hasOneUse()) {
2096 // Adding a one to a single bit bit-field should be turned into an XOR
2097 // of the bit. First thing to check is to see if this AND is with a
2098 // single bit constant.
2099 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
2101 // Clear bits that are not part of the constant.
2102 AndRHSV &= AndRHS->getType()->getIntegralTypeMask();
2104 // If there is only one bit set...
2105 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
2106 // Ok, at this point, we know that we are masking the result of the
2107 // ADD down to exactly one bit. If the constant we are adding has
2108 // no bits set below this bit, then we can eliminate the ADD.
2109 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
2111 // Check to see if any bits below the one bit set in AndRHSV are set.
2112 if ((AddRHS & (AndRHSV-1)) == 0) {
2113 // If not, the only thing that can effect the output of the AND is
2114 // the bit specified by AndRHSV. If that bit is set, the effect of
2115 // the XOR is to toggle the bit. If it is clear, then the ADD has
2117 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
2118 TheAnd.setOperand(0, X);
2121 std::string Name = Op->getName(); Op->setName("");
2122 // Pull the XOR out of the AND.
2123 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
2124 InsertNewInstBefore(NewAnd, TheAnd);
2125 return BinaryOperator::createXor(NewAnd, AndRHS);
2132 case Instruction::Shl: {
2133 // We know that the AND will not produce any of the bits shifted in, so if
2134 // the anded constant includes them, clear them now!
2136 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
2137 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
2138 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
2140 if (CI == ShlMask) { // Masking out bits that the shift already masks
2141 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
2142 } else if (CI != AndRHS) { // Reducing bits set in and.
2143 TheAnd.setOperand(1, CI);
2148 case Instruction::Shr:
2149 // We know that the AND will not produce any of the bits shifted in, so if
2150 // the anded constant includes them, clear them now! This only applies to
2151 // unsigned shifts, because a signed shr may bring in set bits!
2153 if (AndRHS->getType()->isUnsigned()) {
2154 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
2155 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
2156 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
2158 if (CI == ShrMask) { // Masking out bits that the shift already masks.
2159 return ReplaceInstUsesWith(TheAnd, Op);
2160 } else if (CI != AndRHS) {
2161 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
2164 } else { // Signed shr.
2165 // See if this is shifting in some sign extension, then masking it out
2167 if (Op->hasOneUse()) {
2168 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
2169 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
2170 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
2171 if (CI == AndRHS) { // Masking out bits shifted in.
2172 // Make the argument unsigned.
2173 Value *ShVal = Op->getOperand(0);
2174 ShVal = InsertCastBefore(ShVal,
2175 ShVal->getType()->getUnsignedVersion(),
2177 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
2178 OpRHS, Op->getName()),
2180 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
2181 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
2184 return new CastInst(ShVal, Op->getType());
2194 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
2195 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
2196 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
2197 /// insert new instructions.
2198 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
2199 bool Inside, Instruction &IB) {
2200 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
2201 "Lo is not <= Hi in range emission code!");
2203 if (Lo == Hi) // Trivially false.
2204 return new SetCondInst(Instruction::SetNE, V, V);
2205 if (cast<ConstantIntegral>(Lo)->isMinValue())
2206 return new SetCondInst(Instruction::SetLT, V, Hi);
2208 Constant *AddCST = ConstantExpr::getNeg(Lo);
2209 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
2210 InsertNewInstBefore(Add, IB);
2211 // Convert to unsigned for the comparison.
2212 const Type *UnsType = Add->getType()->getUnsignedVersion();
2213 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
2214 AddCST = ConstantExpr::getAdd(AddCST, Hi);
2215 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2216 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2219 if (Lo == Hi) // Trivially true.
2220 return new SetCondInst(Instruction::SetEQ, V, V);
2222 Hi = SubOne(cast<ConstantInt>(Hi));
2223 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
2224 return new SetCondInst(Instruction::SetGT, V, Hi);
2226 // Emit X-Lo > Hi-Lo-1
2227 Constant *AddCST = ConstantExpr::getNeg(Lo);
2228 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
2229 InsertNewInstBefore(Add, IB);
2230 // Convert to unsigned for the comparison.
2231 const Type *UnsType = Add->getType()->getUnsignedVersion();
2232 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
2233 AddCST = ConstantExpr::getAdd(AddCST, Hi);
2234 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2235 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
2238 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
2239 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
2240 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
2241 // not, since all 1s are not contiguous.
2242 static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
2243 uint64_t V = Val->getRawValue();
2244 if (!isShiftedMask_64(V)) return false;
2246 // look for the first zero bit after the run of ones
2247 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
2248 // look for the first non-zero bit
2249 ME = 64-CountLeadingZeros_64(V);
2255 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
2256 /// where isSub determines whether the operator is a sub. If we can fold one of
2257 /// the following xforms:
2259 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
2260 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
2261 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
2263 /// return (A +/- B).
2265 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
2266 ConstantIntegral *Mask, bool isSub,
2268 Instruction *LHSI = dyn_cast<Instruction>(LHS);
2269 if (!LHSI || LHSI->getNumOperands() != 2 ||
2270 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
2272 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
2274 switch (LHSI->getOpcode()) {
2276 case Instruction::And:
2277 if (ConstantExpr::getAnd(N, Mask) == Mask) {
2278 // If the AndRHS is a power of two minus one (0+1+), this is simple.
2279 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
2282 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
2283 // part, we don't need any explicit masks to take them out of A. If that
2284 // is all N is, ignore it.
2286 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
2287 uint64_t Mask = RHS->getType()->getIntegralTypeMask();
2289 if (MaskedValueIsZero(RHS, Mask))
2294 case Instruction::Or:
2295 case Instruction::Xor:
2296 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
2297 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0 &&
2298 ConstantExpr::getAnd(N, Mask)->isNullValue())
2305 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
2307 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
2308 return InsertNewInstBefore(New, I);
2311 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
2312 bool Changed = SimplifyCommutative(I);
2313 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2315 if (isa<UndefValue>(Op1)) // X & undef -> 0
2316 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2320 return ReplaceInstUsesWith(I, Op1);
2322 // See if we can simplify any instructions used by the instruction whose sole
2323 // purpose is to compute bits we don't care about.
2324 uint64_t KnownZero, KnownOne;
2325 if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
2326 KnownZero, KnownOne))
2329 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
2330 uint64_t AndRHSMask = AndRHS->getZExtValue();
2331 uint64_t TypeMask = Op0->getType()->getIntegralTypeMask();
2332 uint64_t NotAndRHS = AndRHSMask^TypeMask;
2334 // Optimize a variety of ((val OP C1) & C2) combinations...
2335 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
2336 Instruction *Op0I = cast<Instruction>(Op0);
2337 Value *Op0LHS = Op0I->getOperand(0);
2338 Value *Op0RHS = Op0I->getOperand(1);
2339 switch (Op0I->getOpcode()) {
2340 case Instruction::Xor:
2341 case Instruction::Or:
2342 // If the mask is only needed on one incoming arm, push it up.
2343 if (Op0I->hasOneUse()) {
2344 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
2345 // Not masking anything out for the LHS, move to RHS.
2346 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
2347 Op0RHS->getName()+".masked");
2348 InsertNewInstBefore(NewRHS, I);
2349 return BinaryOperator::create(
2350 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
2352 if (!isa<Constant>(Op0RHS) &&
2353 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
2354 // Not masking anything out for the RHS, move to LHS.
2355 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
2356 Op0LHS->getName()+".masked");
2357 InsertNewInstBefore(NewLHS, I);
2358 return BinaryOperator::create(
2359 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
2364 case Instruction::Add:
2365 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
2366 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
2367 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
2368 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
2369 return BinaryOperator::createAnd(V, AndRHS);
2370 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
2371 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
2374 case Instruction::Sub:
2375 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
2376 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
2377 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
2378 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
2379 return BinaryOperator::createAnd(V, AndRHS);
2383 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2384 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
2386 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
2387 const Type *SrcTy = CI->getOperand(0)->getType();
2389 // If this is an integer truncation or change from signed-to-unsigned, and
2390 // if the source is an and/or with immediate, transform it. This
2391 // frequently occurs for bitfield accesses.
2392 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
2393 if (SrcTy->getPrimitiveSizeInBits() >=
2394 I.getType()->getPrimitiveSizeInBits() &&
2395 CastOp->getNumOperands() == 2)
2396 if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1)))
2397 if (CastOp->getOpcode() == Instruction::And) {
2398 // Change: and (cast (and X, C1) to T), C2
2399 // into : and (cast X to T), trunc(C1)&C2
2400 // This will folds the two ands together, which may allow other
2402 Instruction *NewCast =
2403 new CastInst(CastOp->getOperand(0), I.getType(),
2404 CastOp->getName()+".shrunk");
2405 NewCast = InsertNewInstBefore(NewCast, I);
2407 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
2408 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
2409 return BinaryOperator::createAnd(NewCast, C3);
2410 } else if (CastOp->getOpcode() == Instruction::Or) {
2411 // Change: and (cast (or X, C1) to T), C2
2412 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
2413 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
2414 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
2415 return ReplaceInstUsesWith(I, AndRHS);
2420 // Try to fold constant and into select arguments.
2421 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2422 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2424 if (isa<PHINode>(Op0))
2425 if (Instruction *NV = FoldOpIntoPhi(I))
2429 Value *Op0NotVal = dyn_castNotVal(Op0);
2430 Value *Op1NotVal = dyn_castNotVal(Op1);
2432 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
2433 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2435 // (~A & ~B) == (~(A | B)) - De Morgan's Law
2436 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2437 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
2438 I.getName()+".demorgan");
2439 InsertNewInstBefore(Or, I);
2440 return BinaryOperator::createNot(Or);
2443 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
2444 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
2445 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2448 Value *LHSVal, *RHSVal;
2449 ConstantInt *LHSCst, *RHSCst;
2450 Instruction::BinaryOps LHSCC, RHSCC;
2451 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2452 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2453 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
2454 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2455 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2456 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2457 // Ensure that the larger constant is on the RHS.
2458 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2459 SetCondInst *LHS = cast<SetCondInst>(Op0);
2460 if (cast<ConstantBool>(Cmp)->getValue()) {
2461 std::swap(LHS, RHS);
2462 std::swap(LHSCst, RHSCst);
2463 std::swap(LHSCC, RHSCC);
2466 // At this point, we know we have have two setcc instructions
2467 // comparing a value against two constants and and'ing the result
2468 // together. Because of the above check, we know that we only have
2469 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2470 // FoldSetCCLogical check above), that the two constants are not
2472 assert(LHSCst != RHSCst && "Compares not folded above?");
2475 default: assert(0 && "Unknown integer condition code!");
2476 case Instruction::SetEQ:
2478 default: assert(0 && "Unknown integer condition code!");
2479 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
2480 case Instruction::SetGT: // (X == 13 & X > 15) -> false
2481 return ReplaceInstUsesWith(I, ConstantBool::False);
2482 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
2483 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
2484 return ReplaceInstUsesWith(I, LHS);
2486 case Instruction::SetNE:
2488 default: assert(0 && "Unknown integer condition code!");
2489 case Instruction::SetLT:
2490 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
2491 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
2492 break; // (X != 13 & X < 15) -> no change
2493 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
2494 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
2495 return ReplaceInstUsesWith(I, RHS);
2496 case Instruction::SetNE:
2497 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
2498 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2499 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2500 LHSVal->getName()+".off");
2501 InsertNewInstBefore(Add, I);
2502 const Type *UnsType = Add->getType()->getUnsignedVersion();
2503 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2504 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
2505 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2506 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
2508 break; // (X != 13 & X != 15) -> no change
2511 case Instruction::SetLT:
2513 default: assert(0 && "Unknown integer condition code!");
2514 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
2515 case Instruction::SetGT: // (X < 13 & X > 15) -> false
2516 return ReplaceInstUsesWith(I, ConstantBool::False);
2517 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
2518 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
2519 return ReplaceInstUsesWith(I, LHS);
2521 case Instruction::SetGT:
2523 default: assert(0 && "Unknown integer condition code!");
2524 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
2525 return ReplaceInstUsesWith(I, LHS);
2526 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
2527 return ReplaceInstUsesWith(I, RHS);
2528 case Instruction::SetNE:
2529 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
2530 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
2531 break; // (X > 13 & X != 15) -> no change
2532 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
2533 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
2539 return Changed ? &I : 0;
2542 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
2543 bool Changed = SimplifyCommutative(I);
2544 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2546 if (isa<UndefValue>(Op1))
2547 return ReplaceInstUsesWith(I, // X | undef -> -1
2548 ConstantIntegral::getAllOnesValue(I.getType()));
2552 return ReplaceInstUsesWith(I, Op0);
2554 // See if we can simplify any instructions used by the instruction whose sole
2555 // purpose is to compute bits we don't care about.
2556 uint64_t KnownZero, KnownOne;
2557 if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
2558 KnownZero, KnownOne))
2562 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2563 ConstantInt *C1 = 0; Value *X = 0;
2564 // (X & C1) | C2 --> (X | C2) & (C1|C2)
2565 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2566 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
2568 InsertNewInstBefore(Or, I);
2569 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
2572 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
2573 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2574 std::string Op0Name = Op0->getName(); Op0->setName("");
2575 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
2576 InsertNewInstBefore(Or, I);
2577 return BinaryOperator::createXor(Or,
2578 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
2581 // Try to fold constant and into select arguments.
2582 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2583 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2585 if (isa<PHINode>(Op0))
2586 if (Instruction *NV = FoldOpIntoPhi(I))
2590 Value *A = 0, *B = 0;
2591 ConstantInt *C1 = 0, *C2 = 0;
2593 if (match(Op0, m_And(m_Value(A), m_Value(B))))
2594 if (A == Op1 || B == Op1) // (A & ?) | A --> A
2595 return ReplaceInstUsesWith(I, Op1);
2596 if (match(Op1, m_And(m_Value(A), m_Value(B))))
2597 if (A == Op0 || B == Op0) // A | (A & ?) --> A
2598 return ReplaceInstUsesWith(I, Op0);
2600 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
2601 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2602 MaskedValueIsZero(Op1, C1->getZExtValue())) {
2603 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
2605 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2608 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
2609 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2610 MaskedValueIsZero(Op0, C1->getZExtValue())) {
2611 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
2613 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2616 // (A & C1)|(B & C2)
2617 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2618 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
2620 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
2621 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
2624 // If we have: ((V + N) & C1) | (V & C2)
2625 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2626 // replace with V+N.
2627 if (C1 == ConstantExpr::getNot(C2)) {
2628 Value *V1 = 0, *V2 = 0;
2629 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2630 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2631 // Add commutes, try both ways.
2632 if (V1 == B && MaskedValueIsZero(V2, C2->getZExtValue()))
2633 return ReplaceInstUsesWith(I, A);
2634 if (V2 == B && MaskedValueIsZero(V1, C2->getZExtValue()))
2635 return ReplaceInstUsesWith(I, A);
2637 // Or commutes, try both ways.
2638 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2639 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2640 // Add commutes, try both ways.
2641 if (V1 == A && MaskedValueIsZero(V2, C1->getZExtValue()))
2642 return ReplaceInstUsesWith(I, B);
2643 if (V2 == A && MaskedValueIsZero(V1, C1->getZExtValue()))
2644 return ReplaceInstUsesWith(I, B);
2649 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2650 if (A == Op1) // ~A | A == -1
2651 return ReplaceInstUsesWith(I,
2652 ConstantIntegral::getAllOnesValue(I.getType()));
2656 // Note, A is still live here!
2657 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2659 return ReplaceInstUsesWith(I,
2660 ConstantIntegral::getAllOnesValue(I.getType()));
2662 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2663 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2664 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2665 I.getName()+".demorgan"), I);
2666 return BinaryOperator::createNot(And);
2670 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2671 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2672 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2675 Value *LHSVal, *RHSVal;
2676 ConstantInt *LHSCst, *RHSCst;
2677 Instruction::BinaryOps LHSCC, RHSCC;
2678 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2679 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2680 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2681 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2682 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2683 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2684 // Ensure that the larger constant is on the RHS.
2685 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2686 SetCondInst *LHS = cast<SetCondInst>(Op0);
2687 if (cast<ConstantBool>(Cmp)->getValue()) {
2688 std::swap(LHS, RHS);
2689 std::swap(LHSCst, RHSCst);
2690 std::swap(LHSCC, RHSCC);
2693 // At this point, we know we have have two setcc instructions
2694 // comparing a value against two constants and or'ing the result
2695 // together. Because of the above check, we know that we only have
2696 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2697 // FoldSetCCLogical check above), that the two constants are not
2699 assert(LHSCst != RHSCst && "Compares not folded above?");
2702 default: assert(0 && "Unknown integer condition code!");
2703 case Instruction::SetEQ:
2705 default: assert(0 && "Unknown integer condition code!");
2706 case Instruction::SetEQ:
2707 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2708 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2709 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2710 LHSVal->getName()+".off");
2711 InsertNewInstBefore(Add, I);
2712 const Type *UnsType = Add->getType()->getUnsignedVersion();
2713 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2714 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2715 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2716 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2718 break; // (X == 13 | X == 15) -> no change
2720 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2722 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2723 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2724 return ReplaceInstUsesWith(I, RHS);
2727 case Instruction::SetNE:
2729 default: assert(0 && "Unknown integer condition code!");
2730 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2731 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2732 return ReplaceInstUsesWith(I, LHS);
2733 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2734 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2735 return ReplaceInstUsesWith(I, ConstantBool::True);
2738 case Instruction::SetLT:
2740 default: assert(0 && "Unknown integer condition code!");
2741 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2743 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2744 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2745 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2746 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2747 return ReplaceInstUsesWith(I, RHS);
2750 case Instruction::SetGT:
2752 default: assert(0 && "Unknown integer condition code!");
2753 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2754 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2755 return ReplaceInstUsesWith(I, LHS);
2756 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2757 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2758 return ReplaceInstUsesWith(I, ConstantBool::True);
2764 return Changed ? &I : 0;
2767 // XorSelf - Implements: X ^ X --> 0
2770 XorSelf(Value *rhs) : RHS(rhs) {}
2771 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2772 Instruction *apply(BinaryOperator &Xor) const {
2778 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2779 bool Changed = SimplifyCommutative(I);
2780 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2782 if (isa<UndefValue>(Op1))
2783 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2785 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2786 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2787 assert(Result == &I && "AssociativeOpt didn't work?");
2788 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2791 // See if we can simplify any instructions used by the instruction whose sole
2792 // purpose is to compute bits we don't care about.
2793 uint64_t KnownZero, KnownOne;
2794 if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
2795 KnownZero, KnownOne))
2798 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2799 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2800 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2801 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2802 if (RHS == ConstantBool::True && SCI->hasOneUse())
2803 return new SetCondInst(SCI->getInverseCondition(),
2804 SCI->getOperand(0), SCI->getOperand(1));
2806 // ~(c-X) == X-c-1 == X+(-c-1)
2807 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2808 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2809 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2810 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2811 ConstantInt::get(I.getType(), 1));
2812 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2815 // ~(~X & Y) --> (X | ~Y)
2816 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2817 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2818 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2820 BinaryOperator::createNot(Op0I->getOperand(1),
2821 Op0I->getOperand(1)->getName()+".not");
2822 InsertNewInstBefore(NotY, I);
2823 return BinaryOperator::createOr(Op0NotVal, NotY);
2827 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2828 if (Op0I->getOpcode() == Instruction::Add) {
2829 // ~(X-c) --> (-c-1)-X
2830 if (RHS->isAllOnesValue()) {
2831 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2832 return BinaryOperator::createSub(
2833 ConstantExpr::getSub(NegOp0CI,
2834 ConstantInt::get(I.getType(), 1)),
2835 Op0I->getOperand(0));
2840 // Try to fold constant and into select arguments.
2841 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2842 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2844 if (isa<PHINode>(Op0))
2845 if (Instruction *NV = FoldOpIntoPhi(I))
2849 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2851 return ReplaceInstUsesWith(I,
2852 ConstantIntegral::getAllOnesValue(I.getType()));
2854 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2856 return ReplaceInstUsesWith(I,
2857 ConstantIntegral::getAllOnesValue(I.getType()));
2859 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2860 if (Op1I->getOpcode() == Instruction::Or) {
2861 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2862 cast<BinaryOperator>(Op1I)->swapOperands();
2864 std::swap(Op0, Op1);
2865 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2867 std::swap(Op0, Op1);
2869 } else if (Op1I->getOpcode() == Instruction::Xor) {
2870 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2871 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2872 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2873 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2876 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2877 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2878 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2879 cast<BinaryOperator>(Op0I)->swapOperands();
2880 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2881 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2882 Op1->getName()+".not"), I);
2883 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2885 } else if (Op0I->getOpcode() == Instruction::Xor) {
2886 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2887 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2888 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2889 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2892 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2893 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2894 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2897 return Changed ? &I : 0;
2900 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2901 /// overflowed for this type.
2902 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2904 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2905 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2908 static bool isPositive(ConstantInt *C) {
2909 return cast<ConstantSInt>(C)->getValue() >= 0;
2912 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2913 /// overflowed for this type.
2914 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2916 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2918 if (In1->getType()->isUnsigned())
2919 return cast<ConstantUInt>(Result)->getValue() <
2920 cast<ConstantUInt>(In1)->getValue();
2921 if (isPositive(In1) != isPositive(In2))
2923 if (isPositive(In1))
2924 return cast<ConstantSInt>(Result)->getValue() <
2925 cast<ConstantSInt>(In1)->getValue();
2926 return cast<ConstantSInt>(Result)->getValue() >
2927 cast<ConstantSInt>(In1)->getValue();
2930 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2931 /// code necessary to compute the offset from the base pointer (without adding
2932 /// in the base pointer). Return the result as a signed integer of intptr size.
2933 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2934 TargetData &TD = IC.getTargetData();
2935 gep_type_iterator GTI = gep_type_begin(GEP);
2936 const Type *UIntPtrTy = TD.getIntPtrType();
2937 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2938 Value *Result = Constant::getNullValue(SIntPtrTy);
2940 // Build a mask for high order bits.
2941 uint64_t PtrSizeMask = ~0ULL >> (64-TD.getPointerSize()*8);
2943 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2944 Value *Op = GEP->getOperand(i);
2945 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2946 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2948 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2949 if (!OpC->isNullValue()) {
2950 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2951 Scale = ConstantExpr::getMul(OpC, Scale);
2952 if (Constant *RC = dyn_cast<Constant>(Result))
2953 Result = ConstantExpr::getAdd(RC, Scale);
2955 // Emit an add instruction.
2956 Result = IC.InsertNewInstBefore(
2957 BinaryOperator::createAdd(Result, Scale,
2958 GEP->getName()+".offs"), I);
2962 // Convert to correct type.
2963 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2964 Op->getName()+".c"), I);
2966 // We'll let instcombine(mul) convert this to a shl if possible.
2967 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2968 GEP->getName()+".idx"), I);
2970 // Emit an add instruction.
2971 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2972 GEP->getName()+".offs"), I);
2978 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2979 /// else. At this point we know that the GEP is on the LHS of the comparison.
2980 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2981 Instruction::BinaryOps Cond,
2983 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2985 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2986 if (isa<PointerType>(CI->getOperand(0)->getType()))
2987 RHS = CI->getOperand(0);
2989 Value *PtrBase = GEPLHS->getOperand(0);
2990 if (PtrBase == RHS) {
2991 // As an optimization, we don't actually have to compute the actual value of
2992 // OFFSET if this is a seteq or setne comparison, just return whether each
2993 // index is zero or not.
2994 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2995 Instruction *InVal = 0;
2996 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2997 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2999 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
3000 if (isa<UndefValue>(C)) // undef index -> undef.
3001 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
3002 if (C->isNullValue())
3004 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
3005 EmitIt = false; // This is indexing into a zero sized array?
3006 } else if (isa<ConstantInt>(C))
3007 return ReplaceInstUsesWith(I, // No comparison is needed here.
3008 ConstantBool::get(Cond == Instruction::SetNE));
3013 new SetCondInst(Cond, GEPLHS->getOperand(i),
3014 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
3018 InVal = InsertNewInstBefore(InVal, I);
3019 InsertNewInstBefore(Comp, I);
3020 if (Cond == Instruction::SetNE) // True if any are unequal
3021 InVal = BinaryOperator::createOr(InVal, Comp);
3022 else // True if all are equal
3023 InVal = BinaryOperator::createAnd(InVal, Comp);
3031 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
3032 ConstantBool::get(Cond == Instruction::SetEQ));
3035 // Only lower this if the setcc is the only user of the GEP or if we expect
3036 // the result to fold to a constant!
3037 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
3038 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
3039 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
3040 return new SetCondInst(Cond, Offset,
3041 Constant::getNullValue(Offset->getType()));
3043 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
3044 // If the base pointers are different, but the indices are the same, just
3045 // compare the base pointer.
3046 if (PtrBase != GEPRHS->getOperand(0)) {
3047 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
3048 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
3049 GEPRHS->getOperand(0)->getType();
3051 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
3052 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
3053 IndicesTheSame = false;
3057 // If all indices are the same, just compare the base pointers.
3059 return new SetCondInst(Cond, GEPLHS->getOperand(0),
3060 GEPRHS->getOperand(0));
3062 // Otherwise, the base pointers are different and the indices are
3063 // different, bail out.
3067 // If one of the GEPs has all zero indices, recurse.
3068 bool AllZeros = true;
3069 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
3070 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
3071 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
3076 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
3077 SetCondInst::getSwappedCondition(Cond), I);
3079 // If the other GEP has all zero indices, recurse.
3081 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
3082 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
3083 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
3088 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
3090 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
3091 // If the GEPs only differ by one index, compare it.
3092 unsigned NumDifferences = 0; // Keep track of # differences.
3093 unsigned DiffOperand = 0; // The operand that differs.
3094 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
3095 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
3096 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
3097 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
3098 // Irreconcilable differences.
3102 if (NumDifferences++) break;
3107 if (NumDifferences == 0) // SAME GEP?
3108 return ReplaceInstUsesWith(I, // No comparison is needed here.
3109 ConstantBool::get(Cond == Instruction::SetEQ));
3110 else if (NumDifferences == 1) {
3111 Value *LHSV = GEPLHS->getOperand(DiffOperand);
3112 Value *RHSV = GEPRHS->getOperand(DiffOperand);
3114 // Convert the operands to signed values to make sure to perform a
3115 // signed comparison.
3116 const Type *NewTy = LHSV->getType()->getSignedVersion();
3117 if (LHSV->getType() != NewTy)
3118 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
3119 LHSV->getName()), I);
3120 if (RHSV->getType() != NewTy)
3121 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
3122 RHSV->getName()), I);
3123 return new SetCondInst(Cond, LHSV, RHSV);
3127 // Only lower this if the setcc is the only user of the GEP or if we expect
3128 // the result to fold to a constant!
3129 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
3130 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
3131 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
3132 Value *L = EmitGEPOffset(GEPLHS, I, *this);
3133 Value *R = EmitGEPOffset(GEPRHS, I, *this);
3134 return new SetCondInst(Cond, L, R);
3141 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
3142 bool Changed = SimplifyCommutative(I);
3143 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3144 const Type *Ty = Op0->getType();
3148 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
3150 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
3151 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
3153 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
3154 // addresses never equal each other! We already know that Op0 != Op1.
3155 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
3156 isa<ConstantPointerNull>(Op0)) &&
3157 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
3158 isa<ConstantPointerNull>(Op1)))
3159 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
3161 // setcc's with boolean values can always be turned into bitwise operations
3162 if (Ty == Type::BoolTy) {
3163 switch (I.getOpcode()) {
3164 default: assert(0 && "Invalid setcc instruction!");
3165 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
3166 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
3167 InsertNewInstBefore(Xor, I);
3168 return BinaryOperator::createNot(Xor);
3170 case Instruction::SetNE:
3171 return BinaryOperator::createXor(Op0, Op1);
3173 case Instruction::SetGT:
3174 std::swap(Op0, Op1); // Change setgt -> setlt
3176 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
3177 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
3178 InsertNewInstBefore(Not, I);
3179 return BinaryOperator::createAnd(Not, Op1);
3181 case Instruction::SetGE:
3182 std::swap(Op0, Op1); // Change setge -> setle
3184 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
3185 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
3186 InsertNewInstBefore(Not, I);
3187 return BinaryOperator::createOr(Not, Op1);
3192 // See if we are doing a comparison between a constant and an instruction that
3193 // can be folded into the comparison.
3194 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
3195 // Check to see if we are comparing against the minimum or maximum value...
3196 if (CI->isMinValue()) {
3197 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
3198 return ReplaceInstUsesWith(I, ConstantBool::False);
3199 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
3200 return ReplaceInstUsesWith(I, ConstantBool::True);
3201 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
3202 return BinaryOperator::createSetEQ(Op0, Op1);
3203 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
3204 return BinaryOperator::createSetNE(Op0, Op1);
3206 } else if (CI->isMaxValue()) {
3207 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
3208 return ReplaceInstUsesWith(I, ConstantBool::False);
3209 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
3210 return ReplaceInstUsesWith(I, ConstantBool::True);
3211 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
3212 return BinaryOperator::createSetEQ(Op0, Op1);
3213 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
3214 return BinaryOperator::createSetNE(Op0, Op1);
3216 // Comparing against a value really close to min or max?
3217 } else if (isMinValuePlusOne(CI)) {
3218 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
3219 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
3220 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
3221 return BinaryOperator::createSetNE(Op0, SubOne(CI));
3223 } else if (isMaxValueMinusOne(CI)) {
3224 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
3225 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
3226 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
3227 return BinaryOperator::createSetNE(Op0, AddOne(CI));
3230 // If we still have a setle or setge instruction, turn it into the
3231 // appropriate setlt or setgt instruction. Since the border cases have
3232 // already been handled above, this requires little checking.
3234 if (I.getOpcode() == Instruction::SetLE)
3235 return BinaryOperator::createSetLT(Op0, AddOne(CI));
3236 if (I.getOpcode() == Instruction::SetGE)
3237 return BinaryOperator::createSetGT(Op0, SubOne(CI));
3240 // See if we can fold the comparison based on bits known to be zero or one
3242 uint64_t KnownZero, KnownOne;
3243 if (SimplifyDemandedBits(Op0, Ty->getIntegralTypeMask(),
3244 KnownZero, KnownOne, 0))
3247 // Given the known and unknown bits, compute a range that the LHS could be
3249 if (KnownOne | KnownZero) {
3250 if (Ty->isUnsigned()) { // Unsigned comparison.
3252 uint64_t RHSVal = CI->getZExtValue();
3253 ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne,
3255 switch (I.getOpcode()) { // LE/GE have been folded already.
3256 default: assert(0 && "Unknown setcc opcode!");
3257 case Instruction::SetEQ:
3258 if (Max < RHSVal || Min > RHSVal)
3259 return ReplaceInstUsesWith(I, ConstantBool::False);
3261 case Instruction::SetNE:
3262 if (Max < RHSVal || Min > RHSVal)
3263 return ReplaceInstUsesWith(I, ConstantBool::True);
3265 case Instruction::SetLT:
3266 if (Max < RHSVal) return ReplaceInstUsesWith(I, ConstantBool::True);
3267 if (Min > RHSVal) return ReplaceInstUsesWith(I, ConstantBool::False);
3269 case Instruction::SetGT:
3270 if (Min > RHSVal) return ReplaceInstUsesWith(I, ConstantBool::True);
3271 if (Max < RHSVal) return ReplaceInstUsesWith(I, ConstantBool::False);
3274 } else { // Signed comparison.
3276 int64_t RHSVal = CI->getSExtValue();
3277 ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne,
3279 switch (I.getOpcode()) { // LE/GE have been folded already.
3280 default: assert(0 && "Unknown setcc opcode!");
3281 case Instruction::SetEQ:
3282 if (Max < RHSVal || Min > RHSVal)
3283 return ReplaceInstUsesWith(I, ConstantBool::False);
3285 case Instruction::SetNE:
3286 if (Max < RHSVal || Min > RHSVal)
3287 return ReplaceInstUsesWith(I, ConstantBool::True);
3289 case Instruction::SetLT:
3290 if (Max < RHSVal) return ReplaceInstUsesWith(I, ConstantBool::True);
3291 if (Min > RHSVal) return ReplaceInstUsesWith(I, ConstantBool::False);
3293 case Instruction::SetGT:
3294 if (Min > RHSVal) return ReplaceInstUsesWith(I, ConstantBool::True);
3295 if (Max < RHSVal) return ReplaceInstUsesWith(I, ConstantBool::False);
3302 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3303 switch (LHSI->getOpcode()) {
3304 case Instruction::And:
3305 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
3306 LHSI->getOperand(0)->hasOneUse()) {
3307 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
3308 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
3309 // happens a LOT in code produced by the C front-end, for bitfield
3311 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
3312 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
3314 // Check to see if there is a noop-cast between the shift and the and.
3316 if (CastInst *CI = dyn_cast<CastInst>(LHSI->getOperand(0)))
3317 if (CI->getOperand(0)->getType()->isIntegral() &&
3318 CI->getOperand(0)->getType()->getPrimitiveSizeInBits() ==
3319 CI->getType()->getPrimitiveSizeInBits())
3320 Shift = dyn_cast<ShiftInst>(CI->getOperand(0));
3323 ConstantUInt *ShAmt;
3324 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
3325 const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
3326 const Type *AndTy = AndCST->getType(); // Type of the and.
3328 // We can fold this as long as we can't shift unknown bits
3329 // into the mask. This can only happen with signed shift
3330 // rights, as they sign-extend.
3332 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
3335 // To test for the bad case of the signed shr, see if any
3336 // of the bits shifted in could be tested after the mask.
3337 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
3338 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
3340 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
3342 ConstantExpr::getShl(ConstantInt::getAllOnesValue(AndTy),
3344 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
3350 if (Shift->getOpcode() == Instruction::Shl)
3351 NewCst = ConstantExpr::getUShr(CI, ShAmt);
3353 NewCst = ConstantExpr::getShl(CI, ShAmt);
3355 // Check to see if we are shifting out any of the bits being
3357 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
3358 // If we shifted bits out, the fold is not going to work out.
3359 // As a special case, check to see if this means that the
3360 // result is always true or false now.
3361 if (I.getOpcode() == Instruction::SetEQ)
3362 return ReplaceInstUsesWith(I, ConstantBool::False);
3363 if (I.getOpcode() == Instruction::SetNE)
3364 return ReplaceInstUsesWith(I, ConstantBool::True);
3366 I.setOperand(1, NewCst);
3367 Constant *NewAndCST;
3368 if (Shift->getOpcode() == Instruction::Shl)
3369 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
3371 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
3372 LHSI->setOperand(1, NewAndCST);
3374 LHSI->setOperand(0, Shift->getOperand(0));
3376 Value *NewCast = InsertCastBefore(Shift->getOperand(0), AndTy,
3378 LHSI->setOperand(0, NewCast);
3380 WorkList.push_back(Shift); // Shift is dead.
3381 AddUsesToWorkList(I);
3389 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
3390 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
3391 switch (I.getOpcode()) {
3393 case Instruction::SetEQ:
3394 case Instruction::SetNE: {
3395 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
3397 // Check that the shift amount is in range. If not, don't perform
3398 // undefined shifts. When the shift is visited it will be
3400 if (ShAmt->getValue() >= TypeBits)
3403 // If we are comparing against bits always shifted out, the
3404 // comparison cannot succeed.
3406 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
3407 if (Comp != CI) {// Comparing against a bit that we know is zero.
3408 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
3409 Constant *Cst = ConstantBool::get(IsSetNE);
3410 return ReplaceInstUsesWith(I, Cst);
3413 if (LHSI->hasOneUse()) {
3414 // Otherwise strength reduce the shift into an and.
3415 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
3416 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
3419 if (CI->getType()->isUnsigned()) {
3420 Mask = ConstantUInt::get(CI->getType(), Val);
3421 } else if (ShAmtVal != 0) {
3422 Mask = ConstantSInt::get(CI->getType(), Val);
3424 Mask = ConstantInt::getAllOnesValue(CI->getType());
3428 BinaryOperator::createAnd(LHSI->getOperand(0),
3429 Mask, LHSI->getName()+".mask");
3430 Value *And = InsertNewInstBefore(AndI, I);
3431 return new SetCondInst(I.getOpcode(), And,
3432 ConstantExpr::getUShr(CI, ShAmt));
3439 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
3440 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
3441 switch (I.getOpcode()) {
3443 case Instruction::SetEQ:
3444 case Instruction::SetNE: {
3446 // Check that the shift amount is in range. If not, don't perform
3447 // undefined shifts. When the shift is visited it will be
3449 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
3450 if (ShAmt->getValue() >= TypeBits)
3453 // If we are comparing against bits always shifted out, the
3454 // comparison cannot succeed.
3456 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
3458 if (Comp != CI) {// Comparing against a bit that we know is zero.
3459 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
3460 Constant *Cst = ConstantBool::get(IsSetNE);
3461 return ReplaceInstUsesWith(I, Cst);
3464 if (LHSI->hasOneUse() || CI->isNullValue()) {
3465 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
3467 // Otherwise strength reduce the shift into an and.
3468 uint64_t Val = ~0ULL; // All ones.
3469 Val <<= ShAmtVal; // Shift over to the right spot.
3472 if (CI->getType()->isUnsigned()) {
3473 Val &= ~0ULL >> (64-TypeBits);
3474 Mask = ConstantUInt::get(CI->getType(), Val);
3476 Mask = ConstantSInt::get(CI->getType(), Val);
3480 BinaryOperator::createAnd(LHSI->getOperand(0),
3481 Mask, LHSI->getName()+".mask");
3482 Value *And = InsertNewInstBefore(AndI, I);
3483 return new SetCondInst(I.getOpcode(), And,
3484 ConstantExpr::getShl(CI, ShAmt));
3492 case Instruction::Div:
3493 // Fold: (div X, C1) op C2 -> range check
3494 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
3495 // Fold this div into the comparison, producing a range check.
3496 // Determine, based on the divide type, what the range is being
3497 // checked. If there is an overflow on the low or high side, remember
3498 // it, otherwise compute the range [low, hi) bounding the new value.
3499 bool LoOverflow = false, HiOverflow = 0;
3500 ConstantInt *LoBound = 0, *HiBound = 0;
3503 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
3505 Instruction::BinaryOps Opcode = I.getOpcode();
3507 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
3508 } else if (LHSI->getType()->isUnsigned()) { // udiv
3510 LoOverflow = ProdOV;
3511 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
3512 } else if (isPositive(DivRHS)) { // Divisor is > 0.
3513 if (CI->isNullValue()) { // (X / pos) op 0
3515 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
3517 } else if (isPositive(CI)) { // (X / pos) op pos
3519 LoOverflow = ProdOV;
3520 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
3521 } else { // (X / pos) op neg
3522 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
3523 LoOverflow = AddWithOverflow(LoBound, Prod,
3524 cast<ConstantInt>(DivRHSH));
3526 HiOverflow = ProdOV;
3528 } else { // Divisor is < 0.
3529 if (CI->isNullValue()) { // (X / neg) op 0
3530 LoBound = AddOne(DivRHS);
3531 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
3532 if (HiBound == DivRHS)
3533 LoBound = 0; // - INTMIN = INTMIN
3534 } else if (isPositive(CI)) { // (X / neg) op pos
3535 HiOverflow = LoOverflow = ProdOV;
3537 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
3538 HiBound = AddOne(Prod);
3539 } else { // (X / neg) op neg
3541 LoOverflow = HiOverflow = ProdOV;
3542 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
3545 // Dividing by a negate swaps the condition.
3546 Opcode = SetCondInst::getSwappedCondition(Opcode);
3550 Value *X = LHSI->getOperand(0);
3552 default: assert(0 && "Unhandled setcc opcode!");
3553 case Instruction::SetEQ:
3554 if (LoOverflow && HiOverflow)
3555 return ReplaceInstUsesWith(I, ConstantBool::False);
3556 else if (HiOverflow)
3557 return new SetCondInst(Instruction::SetGE, X, LoBound);
3558 else if (LoOverflow)
3559 return new SetCondInst(Instruction::SetLT, X, HiBound);
3561 return InsertRangeTest(X, LoBound, HiBound, true, I);
3562 case Instruction::SetNE:
3563 if (LoOverflow && HiOverflow)
3564 return ReplaceInstUsesWith(I, ConstantBool::True);
3565 else if (HiOverflow)
3566 return new SetCondInst(Instruction::SetLT, X, LoBound);
3567 else if (LoOverflow)
3568 return new SetCondInst(Instruction::SetGE, X, HiBound);
3570 return InsertRangeTest(X, LoBound, HiBound, false, I);
3571 case Instruction::SetLT:
3573 return ReplaceInstUsesWith(I, ConstantBool::False);
3574 return new SetCondInst(Instruction::SetLT, X, LoBound);
3575 case Instruction::SetGT:
3577 return ReplaceInstUsesWith(I, ConstantBool::False);
3578 return new SetCondInst(Instruction::SetGE, X, HiBound);
3585 // Simplify seteq and setne instructions...
3586 if (I.getOpcode() == Instruction::SetEQ ||
3587 I.getOpcode() == Instruction::SetNE) {
3588 bool isSetNE = I.getOpcode() == Instruction::SetNE;
3590 // If the first operand is (and|or|xor) with a constant, and the second
3591 // operand is a constant, simplify a bit.
3592 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
3593 switch (BO->getOpcode()) {
3594 case Instruction::Rem:
3595 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
3596 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
3598 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
3599 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
3600 if (isPowerOf2_64(V)) {
3601 unsigned L2 = Log2_64(V);
3602 const Type *UTy = BO->getType()->getUnsignedVersion();
3603 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
3605 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
3606 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
3607 RHSCst, BO->getName()), I);
3608 return BinaryOperator::create(I.getOpcode(), NewRem,
3609 Constant::getNullValue(UTy));
3614 case Instruction::Add:
3615 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
3616 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3617 if (BO->hasOneUse())
3618 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3619 ConstantExpr::getSub(CI, BOp1C));
3620 } else if (CI->isNullValue()) {
3621 // Replace ((add A, B) != 0) with (A != -B) if A or B is
3622 // efficiently invertible, or if the add has just this one use.
3623 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
3625 if (Value *NegVal = dyn_castNegVal(BOp1))
3626 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
3627 else if (Value *NegVal = dyn_castNegVal(BOp0))
3628 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
3629 else if (BO->hasOneUse()) {
3630 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
3632 InsertNewInstBefore(Neg, I);
3633 return new SetCondInst(I.getOpcode(), BOp0, Neg);
3637 case Instruction::Xor:
3638 // For the xor case, we can xor two constants together, eliminating
3639 // the explicit xor.
3640 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
3641 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
3642 ConstantExpr::getXor(CI, BOC));
3645 case Instruction::Sub:
3646 // Replace (([sub|xor] A, B) != 0) with (A != B)
3647 if (CI->isNullValue())
3648 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3652 case Instruction::Or:
3653 // If bits are being or'd in that are not present in the constant we
3654 // are comparing against, then the comparison could never succeed!
3655 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
3656 Constant *NotCI = ConstantExpr::getNot(CI);
3657 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
3658 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3662 case Instruction::And:
3663 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3664 // If bits are being compared against that are and'd out, then the
3665 // comparison can never succeed!
3666 if (!ConstantExpr::getAnd(CI,
3667 ConstantExpr::getNot(BOC))->isNullValue())
3668 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3670 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3671 if (CI == BOC && isOneBitSet(CI))
3672 return new SetCondInst(isSetNE ? Instruction::SetEQ :
3673 Instruction::SetNE, Op0,
3674 Constant::getNullValue(CI->getType()));
3676 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
3677 // to be a signed value as appropriate.
3678 if (isSignBit(BOC)) {
3679 Value *X = BO->getOperand(0);
3680 // If 'X' is not signed, insert a cast now...
3681 if (!BOC->getType()->isSigned()) {
3682 const Type *DestTy = BOC->getType()->getSignedVersion();
3683 X = InsertCastBefore(X, DestTy, I);
3685 return new SetCondInst(isSetNE ? Instruction::SetLT :
3686 Instruction::SetGE, X,
3687 Constant::getNullValue(X->getType()));
3690 // ((X & ~7) == 0) --> X < 8
3691 if (CI->isNullValue() && isHighOnes(BOC)) {
3692 Value *X = BO->getOperand(0);
3693 Constant *NegX = ConstantExpr::getNeg(BOC);
3695 // If 'X' is signed, insert a cast now.
3696 if (NegX->getType()->isSigned()) {
3697 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3698 X = InsertCastBefore(X, DestTy, I);
3699 NegX = ConstantExpr::getCast(NegX, DestTy);
3702 return new SetCondInst(isSetNE ? Instruction::SetGE :
3703 Instruction::SetLT, X, NegX);
3710 } else { // Not a SetEQ/SetNE
3711 // If the LHS is a cast from an integral value of the same size,
3712 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3713 Value *CastOp = Cast->getOperand(0);
3714 const Type *SrcTy = CastOp->getType();
3715 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3716 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3717 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3718 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3719 "Source and destination signednesses should differ!");
3720 if (Cast->getType()->isSigned()) {
3721 // If this is a signed comparison, check for comparisons in the
3722 // vicinity of zero.
3723 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3725 return BinaryOperator::createSetGT(CastOp,
3726 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3727 else if (I.getOpcode() == Instruction::SetGT &&
3728 cast<ConstantSInt>(CI)->getValue() == -1)
3729 // X > -1 => x < 128
3730 return BinaryOperator::createSetLT(CastOp,
3731 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3733 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3734 if (I.getOpcode() == Instruction::SetLT &&
3735 CUI->getValue() == 1ULL << (SrcTySize-1))
3736 // X < 128 => X > -1
3737 return BinaryOperator::createSetGT(CastOp,
3738 ConstantSInt::get(SrcTy, -1));
3739 else if (I.getOpcode() == Instruction::SetGT &&
3740 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3742 return BinaryOperator::createSetLT(CastOp,
3743 Constant::getNullValue(SrcTy));
3750 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3751 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3752 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3753 switch (LHSI->getOpcode()) {
3754 case Instruction::GetElementPtr:
3755 if (RHSC->isNullValue()) {
3756 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3757 bool isAllZeros = true;
3758 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3759 if (!isa<Constant>(LHSI->getOperand(i)) ||
3760 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3765 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3766 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3770 case Instruction::PHI:
3771 if (Instruction *NV = FoldOpIntoPhi(I))
3774 case Instruction::Select:
3775 // If either operand of the select is a constant, we can fold the
3776 // comparison into the select arms, which will cause one to be
3777 // constant folded and the select turned into a bitwise or.
3778 Value *Op1 = 0, *Op2 = 0;
3779 if (LHSI->hasOneUse()) {
3780 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3781 // Fold the known value into the constant operand.
3782 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3783 // Insert a new SetCC of the other select operand.
3784 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3785 LHSI->getOperand(2), RHSC,
3787 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3788 // Fold the known value into the constant operand.
3789 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3790 // Insert a new SetCC of the other select operand.
3791 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3792 LHSI->getOperand(1), RHSC,
3798 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3803 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3804 if (User *GEP = dyn_castGetElementPtr(Op0))
3805 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3807 if (User *GEP = dyn_castGetElementPtr(Op1))
3808 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3809 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3812 // Test to see if the operands of the setcc are casted versions of other
3813 // values. If the cast can be stripped off both arguments, we do so now.
3814 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3815 Value *CastOp0 = CI->getOperand(0);
3816 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3817 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3818 (I.getOpcode() == Instruction::SetEQ ||
3819 I.getOpcode() == Instruction::SetNE)) {
3820 // We keep moving the cast from the left operand over to the right
3821 // operand, where it can often be eliminated completely.
3824 // If operand #1 is a cast instruction, see if we can eliminate it as
3826 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3827 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3829 Op1 = CI2->getOperand(0);
3831 // If Op1 is a constant, we can fold the cast into the constant.
3832 if (Op1->getType() != Op0->getType())
3833 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3834 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3836 // Otherwise, cast the RHS right before the setcc
3837 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3838 InsertNewInstBefore(cast<Instruction>(Op1), I);
3840 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3843 // Handle the special case of: setcc (cast bool to X), <cst>
3844 // This comes up when you have code like
3847 // For generality, we handle any zero-extension of any operand comparison
3848 // with a constant or another cast from the same type.
3849 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3850 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3853 return Changed ? &I : 0;
3856 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3857 // We only handle extending casts so far.
3859 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3860 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3861 const Type *SrcTy = LHSCIOp->getType();
3862 const Type *DestTy = SCI.getOperand(0)->getType();
3865 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3868 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3869 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3870 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3872 // Is this a sign or zero extension?
3873 bool isSignSrc = SrcTy->isSigned();
3874 bool isSignDest = DestTy->isSigned();
3876 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3877 // Not an extension from the same type?
3878 RHSCIOp = CI->getOperand(0);
3879 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3880 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3881 // Compute the constant that would happen if we truncated to SrcTy then
3882 // reextended to DestTy.
3883 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3885 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3888 // If the value cannot be represented in the shorter type, we cannot emit
3889 // a simple comparison.
3890 if (SCI.getOpcode() == Instruction::SetEQ)
3891 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3892 if (SCI.getOpcode() == Instruction::SetNE)
3893 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3895 // Evaluate the comparison for LT.
3897 if (DestTy->isSigned()) {
3898 // We're performing a signed comparison.
3900 // Signed extend and signed comparison.
3901 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3902 Result = ConstantBool::False;
3904 Result = ConstantBool::True; // X < (large) --> true
3906 // Unsigned extend and signed comparison.
3907 if (cast<ConstantSInt>(CI)->getValue() < 0)
3908 Result = ConstantBool::False;
3910 Result = ConstantBool::True;
3913 // We're performing an unsigned comparison.
3915 // Unsigned extend & compare -> always true.
3916 Result = ConstantBool::True;
3918 // We're performing an unsigned comp with a sign extended value.
3919 // This is true if the input is >= 0. [aka >s -1]
3920 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3921 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3922 NegOne, SCI.getName()), SCI);
3926 // Finally, return the value computed.
3927 if (SCI.getOpcode() == Instruction::SetLT) {
3928 return ReplaceInstUsesWith(SCI, Result);
3930 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3931 if (Constant *CI = dyn_cast<Constant>(Result))
3932 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3934 return BinaryOperator::createNot(Result);
3941 // Okay, just insert a compare of the reduced operands now!
3942 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3945 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3946 assert(I.getOperand(1)->getType() == Type::UByteTy);
3947 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3948 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3950 // shl X, 0 == X and shr X, 0 == X
3951 // shl 0, X == 0 and shr 0, X == 0
3952 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3953 Op0 == Constant::getNullValue(Op0->getType()))
3954 return ReplaceInstUsesWith(I, Op0);
3956 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3957 if (!isLeftShift && I.getType()->isSigned())
3958 return ReplaceInstUsesWith(I, Op0);
3959 else // undef << X -> 0 AND undef >>u X -> 0
3960 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3962 if (isa<UndefValue>(Op1)) {
3963 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3964 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3966 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3969 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3971 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3972 if (CSI->isAllOnesValue())
3973 return ReplaceInstUsesWith(I, CSI);
3975 // Try to fold constant and into select arguments.
3976 if (isa<Constant>(Op0))
3977 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3978 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3981 // See if we can turn a signed shr into an unsigned shr.
3982 if (!isLeftShift && I.getType()->isSigned()) {
3983 if (MaskedValueIsZero(Op0,
3984 1ULL << (I.getType()->getPrimitiveSizeInBits()-1))) {
3985 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3986 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3988 return new CastInst(V, I.getType());
3992 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1))
3993 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
3998 Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
4000 bool isLeftShift = I.getOpcode() == Instruction::Shl;
4001 bool isSignedShift = Op0->getType()->isSigned();
4002 bool isUnsignedShift = !isSignedShift;
4004 // See if we can simplify any instructions used by the instruction whose sole
4005 // purpose is to compute bits we don't care about.
4006 uint64_t KnownZero, KnownOne;
4007 if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
4008 KnownZero, KnownOne))
4011 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
4012 // of a signed value.
4014 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
4015 if (Op1->getValue() >= TypeBits) {
4016 if (isUnsignedShift || isLeftShift)
4017 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
4019 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
4024 // ((X*C1) << C2) == (X * (C1 << C2))
4025 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
4026 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
4027 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
4028 return BinaryOperator::createMul(BO->getOperand(0),
4029 ConstantExpr::getShl(BOOp, Op1));
4031 // Try to fold constant and into select arguments.
4032 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
4033 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
4035 if (isa<PHINode>(Op0))
4036 if (Instruction *NV = FoldOpIntoPhi(I))
4039 if (Op0->hasOneUse()) {
4040 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
4041 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
4044 switch (Op0BO->getOpcode()) {
4046 case Instruction::Add:
4047 case Instruction::And:
4048 case Instruction::Or:
4049 case Instruction::Xor:
4050 // These operators commute.
4051 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
4052 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
4053 match(Op0BO->getOperand(1),
4054 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
4055 Instruction *YS = new ShiftInst(Instruction::Shl,
4056 Op0BO->getOperand(0), Op1,
4058 InsertNewInstBefore(YS, I); // (Y << C)
4060 BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
4061 Op0BO->getOperand(1)->getName());
4062 InsertNewInstBefore(X, I); // (X + (Y << C))
4063 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
4064 C2 = ConstantExpr::getShl(C2, Op1);
4065 return BinaryOperator::createAnd(X, C2);
4068 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
4069 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
4070 match(Op0BO->getOperand(1),
4071 m_And(m_Shr(m_Value(V1), m_Value(V2)),
4072 m_ConstantInt(CC))) && V2 == Op1 &&
4073 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
4074 Instruction *YS = new ShiftInst(Instruction::Shl,
4075 Op0BO->getOperand(0), Op1,
4077 InsertNewInstBefore(YS, I); // (Y << C)
4079 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
4080 V1->getName()+".mask");
4081 InsertNewInstBefore(XM, I); // X & (CC << C)
4083 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
4087 case Instruction::Sub:
4088 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
4089 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
4090 match(Op0BO->getOperand(0),
4091 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
4092 Instruction *YS = new ShiftInst(Instruction::Shl,
4093 Op0BO->getOperand(1), Op1,
4095 InsertNewInstBefore(YS, I); // (Y << C)
4097 BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
4098 Op0BO->getOperand(0)->getName());
4099 InsertNewInstBefore(X, I); // (X + (Y << C))
4100 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
4101 C2 = ConstantExpr::getShl(C2, Op1);
4102 return BinaryOperator::createAnd(X, C2);
4105 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
4106 match(Op0BO->getOperand(0),
4107 m_And(m_Shr(m_Value(V1), m_Value(V2)),
4108 m_ConstantInt(CC))) && V2 == Op1 &&
4109 cast<BinaryOperator>(Op0BO->getOperand(0))
4110 ->getOperand(0)->hasOneUse()) {
4111 Instruction *YS = new ShiftInst(Instruction::Shl,
4112 Op0BO->getOperand(1), Op1,
4114 InsertNewInstBefore(YS, I); // (Y << C)
4116 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
4117 V1->getName()+".mask");
4118 InsertNewInstBefore(XM, I); // X & (CC << C)
4120 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
4127 // If the operand is an bitwise operator with a constant RHS, and the
4128 // shift is the only use, we can pull it out of the shift.
4129 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
4130 bool isValid = true; // Valid only for And, Or, Xor
4131 bool highBitSet = false; // Transform if high bit of constant set?
4133 switch (Op0BO->getOpcode()) {
4134 default: isValid = false; break; // Do not perform transform!
4135 case Instruction::Add:
4136 isValid = isLeftShift;
4138 case Instruction::Or:
4139 case Instruction::Xor:
4142 case Instruction::And:
4147 // If this is a signed shift right, and the high bit is modified
4148 // by the logical operation, do not perform the transformation.
4149 // The highBitSet boolean indicates the value of the high bit of
4150 // the constant which would cause it to be modified for this
4153 if (isValid && !isLeftShift && isSignedShift) {
4154 uint64_t Val = Op0C->getRawValue();
4155 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
4159 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
4161 Instruction *NewShift =
4162 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), Op1,
4165 InsertNewInstBefore(NewShift, I);
4167 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
4174 // Find out if this is a shift of a shift by a constant.
4175 ShiftInst *ShiftOp = 0;
4176 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
4178 else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
4179 // If this is a noop-integer case of a shift instruction, use the shift.
4180 if (CI->getOperand(0)->getType()->isInteger() &&
4181 CI->getOperand(0)->getType()->getPrimitiveSizeInBits() ==
4182 CI->getType()->getPrimitiveSizeInBits() &&
4183 isa<ShiftInst>(CI->getOperand(0))) {
4184 ShiftOp = cast<ShiftInst>(CI->getOperand(0));
4188 if (ShiftOp && isa<ConstantUInt>(ShiftOp->getOperand(1))) {
4189 // Find the operands and properties of the input shift. Note that the
4190 // signedness of the input shift may differ from the current shift if there
4191 // is a noop cast between the two.
4192 bool isShiftOfLeftShift = ShiftOp->getOpcode() == Instruction::Shl;
4193 bool isShiftOfSignedShift = ShiftOp->getType()->isSigned();
4194 bool isShiftOfUnsignedShift = !isShiftOfSignedShift;
4196 ConstantUInt *ShiftAmt1C = cast<ConstantUInt>(ShiftOp->getOperand(1));
4198 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
4199 unsigned ShiftAmt2 = (unsigned)Op1->getValue();
4201 // Check for (A << c1) << c2 and (A >> c1) >> c2.
4202 if (isLeftShift == isShiftOfLeftShift) {
4203 // Do not fold these shifts if the first one is signed and the second one
4204 // is unsigned and this is a right shift. Further, don't do any folding
4206 if (isShiftOfSignedShift && isUnsignedShift && !isLeftShift)
4209 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
4210 if (Amt > Op0->getType()->getPrimitiveSizeInBits())
4211 Amt = Op0->getType()->getPrimitiveSizeInBits();
4213 Value *Op = ShiftOp->getOperand(0);
4214 if (isShiftOfSignedShift != isSignedShift)
4215 Op = InsertNewInstBefore(new CastInst(Op, I.getType(), "tmp"), I);
4216 return new ShiftInst(I.getOpcode(), Op,
4217 ConstantUInt::get(Type::UByteTy, Amt));
4220 // Check for (A << c1) >> c2 or (A >> c1) << c2. If we are dealing with
4221 // signed types, we can only support the (A >> c1) << c2 configuration,
4222 // because it can not turn an arbitrary bit of A into a sign bit.
4223 if (isUnsignedShift || isLeftShift) {
4224 // Calculate bitmask for what gets shifted off the edge.
4225 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
4227 C = ConstantExpr::getShl(C, ShiftAmt1C);
4229 C = ConstantExpr::getUShr(C, ShiftAmt1C);
4231 Value *Op = ShiftOp->getOperand(0);
4232 if (isShiftOfSignedShift != isSignedShift)
4233 Op = InsertNewInstBefore(new CastInst(Op, I.getType(),Op->getName()),I);
4236 BinaryOperator::createAnd(Op, C, Op->getName()+".mask");
4237 InsertNewInstBefore(Mask, I);
4239 // Figure out what flavor of shift we should use...
4240 if (ShiftAmt1 == ShiftAmt2) {
4241 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
4242 } else if (ShiftAmt1 < ShiftAmt2) {
4243 return new ShiftInst(I.getOpcode(), Mask,
4244 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
4245 } else if (isShiftOfUnsignedShift || isShiftOfLeftShift) {
4246 if (isShiftOfUnsignedShift && !isShiftOfLeftShift && isSignedShift) {
4247 // Make sure to emit an unsigned shift right, not a signed one.
4248 Mask = InsertNewInstBefore(new CastInst(Mask,
4249 Mask->getType()->getUnsignedVersion(),
4251 Mask = new ShiftInst(Instruction::Shr, Mask,
4252 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
4253 InsertNewInstBefore(Mask, I);
4254 return new CastInst(Mask, I.getType());
4256 return new ShiftInst(ShiftOp->getOpcode(), Mask,
4257 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
4260 // (X >>s C1) << C2 where C1 > C2 === (X >>s (C1-C2)) & mask
4261 Op = InsertNewInstBefore(new CastInst(Mask,
4262 I.getType()->getSignedVersion(),
4263 Mask->getName()), I);
4264 Instruction *Shift =
4265 new ShiftInst(ShiftOp->getOpcode(), Op,
4266 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
4267 InsertNewInstBefore(Shift, I);
4269 C = ConstantIntegral::getAllOnesValue(Shift->getType());
4270 C = ConstantExpr::getShl(C, Op1);
4271 Mask = BinaryOperator::createAnd(Shift, C, Op->getName()+".mask");
4272 InsertNewInstBefore(Mask, I);
4273 return new CastInst(Mask, I.getType());
4276 // We can handle signed (X << C1) >>s C2 if it's a sign extend. In
4277 // this case, C1 == C2 and C1 is 8, 16, or 32.
4278 if (ShiftAmt1 == ShiftAmt2) {
4279 const Type *SExtType = 0;
4280 switch (ShiftAmt1) {
4281 case 8 : SExtType = Type::SByteTy; break;
4282 case 16: SExtType = Type::ShortTy; break;
4283 case 32: SExtType = Type::IntTy; break;
4287 Instruction *NewTrunc = new CastInst(ShiftOp->getOperand(0),
4289 InsertNewInstBefore(NewTrunc, I);
4290 return new CastInst(NewTrunc, I.getType());
4305 /// getCastType - In the future, we will split the cast instruction into these
4306 /// various types. Until then, we have to do the analysis here.
4307 static CastType getCastType(const Type *Src, const Type *Dest) {
4308 assert(Src->isIntegral() && Dest->isIntegral() &&
4309 "Only works on integral types!");
4310 unsigned SrcSize = Src->getPrimitiveSizeInBits();
4311 unsigned DestSize = Dest->getPrimitiveSizeInBits();
4313 if (SrcSize == DestSize) return Noop;
4314 if (SrcSize > DestSize) return Truncate;
4315 if (Src->isSigned()) return Signext;
4320 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
4323 static bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
4324 const Type *DstTy, TargetData *TD) {
4326 // It is legal to eliminate the instruction if casting A->B->A if the sizes
4327 // are identical and the bits don't get reinterpreted (for example
4328 // int->float->int would not be allowed).
4329 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
4332 // If we are casting between pointer and integer types, treat pointers as
4333 // integers of the appropriate size for the code below.
4334 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
4335 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
4336 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
4338 // Allow free casting and conversion of sizes as long as the sign doesn't
4340 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
4341 CastType FirstCast = getCastType(SrcTy, MidTy);
4342 CastType SecondCast = getCastType(MidTy, DstTy);
4344 // Capture the effect of these two casts. If the result is a legal cast,
4345 // the CastType is stored here, otherwise a special code is used.
4346 static const unsigned CastResult[] = {
4347 // First cast is noop
4349 // First cast is a truncate
4350 1, 1, 4, 4, // trunc->extend is not safe to eliminate
4351 // First cast is a sign ext
4352 2, 5, 2, 4, // signext->zeroext never ok
4353 // First cast is a zero ext
4357 unsigned Result = CastResult[FirstCast*4+SecondCast];
4359 default: assert(0 && "Illegal table value!");
4364 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
4365 // truncates, we could eliminate more casts.
4366 return (unsigned)getCastType(SrcTy, DstTy) == Result;
4368 return false; // Not possible to eliminate this here.
4370 // Sign or zero extend followed by truncate is always ok if the result
4371 // is a truncate or noop.
4372 CastType ResultCast = getCastType(SrcTy, DstTy);
4373 if (ResultCast == Noop || ResultCast == Truncate)
4375 // Otherwise we are still growing the value, we are only safe if the
4376 // result will match the sign/zeroextendness of the result.
4377 return ResultCast == FirstCast;
4381 // If this is a cast from 'float -> double -> integer', cast from
4382 // 'float -> integer' directly, as the value isn't changed by the
4383 // float->double conversion.
4384 if (SrcTy->isFloatingPoint() && MidTy->isFloatingPoint() &&
4385 DstTy->isIntegral() &&
4386 SrcTy->getPrimitiveSize() < MidTy->getPrimitiveSize())
4392 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
4393 if (V->getType() == Ty || isa<Constant>(V)) return false;
4394 if (const CastInst *CI = dyn_cast<CastInst>(V))
4395 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
4401 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
4402 /// InsertBefore instruction. This is specialized a bit to avoid inserting
4403 /// casts that are known to not do anything...
4405 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
4406 Instruction *InsertBefore) {
4407 if (V->getType() == DestTy) return V;
4408 if (Constant *C = dyn_cast<Constant>(V))
4409 return ConstantExpr::getCast(C, DestTy);
4411 CastInst *CI = new CastInst(V, DestTy, V->getName());
4412 InsertNewInstBefore(CI, *InsertBefore);
4416 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
4417 /// expression. If so, decompose it, returning some value X, such that Val is
4420 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
4422 assert(Val->getType() == Type::UIntTy && "Unexpected allocation size type!");
4423 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(Val)) {
4424 Offset = CI->getValue();
4426 return ConstantUInt::get(Type::UIntTy, 0);
4427 } else if (Instruction *I = dyn_cast<Instruction>(Val)) {
4428 if (I->getNumOperands() == 2) {
4429 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I->getOperand(1))) {
4430 if (I->getOpcode() == Instruction::Shl) {
4431 // This is a value scaled by '1 << the shift amt'.
4432 Scale = 1U << CUI->getValue();
4434 return I->getOperand(0);
4435 } else if (I->getOpcode() == Instruction::Mul) {
4436 // This value is scaled by 'CUI'.
4437 Scale = CUI->getValue();
4439 return I->getOperand(0);
4440 } else if (I->getOpcode() == Instruction::Add) {
4441 // We have X+C. Check to see if we really have (X*C2)+C1, where C1 is
4444 Value *SubVal = DecomposeSimpleLinearExpr(I->getOperand(0), SubScale,
4446 Offset += CUI->getValue();
4447 if (SubScale > 1 && (Offset % SubScale == 0)) {
4456 // Otherwise, we can't look past this.
4463 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
4464 /// try to eliminate the cast by moving the type information into the alloc.
4465 Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
4466 AllocationInst &AI) {
4467 const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
4468 if (!PTy) return 0; // Not casting the allocation to a pointer type.
4470 // Remove any uses of AI that are dead.
4471 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
4472 std::vector<Instruction*> DeadUsers;
4473 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
4474 Instruction *User = cast<Instruction>(*UI++);
4475 if (isInstructionTriviallyDead(User)) {
4476 while (UI != E && *UI == User)
4477 ++UI; // If this instruction uses AI more than once, don't break UI.
4479 // Add operands to the worklist.
4480 AddUsesToWorkList(*User);
4482 DEBUG(std::cerr << "IC: DCE: " << *User);
4484 User->eraseFromParent();
4485 removeFromWorkList(User);
4489 // Get the type really allocated and the type casted to.
4490 const Type *AllocElTy = AI.getAllocatedType();
4491 const Type *CastElTy = PTy->getElementType();
4492 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
4494 unsigned AllocElTyAlign = TD->getTypeSize(AllocElTy);
4495 unsigned CastElTyAlign = TD->getTypeSize(CastElTy);
4496 if (CastElTyAlign < AllocElTyAlign) return 0;
4498 // If the allocation has multiple uses, only promote it if we are strictly
4499 // increasing the alignment of the resultant allocation. If we keep it the
4500 // same, we open the door to infinite loops of various kinds.
4501 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
4503 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
4504 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
4505 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
4507 // See if we can satisfy the modulus by pulling a scale out of the array
4509 unsigned ArraySizeScale, ArrayOffset;
4510 Value *NumElements = // See if the array size is a decomposable linear expr.
4511 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
4513 // If we can now satisfy the modulus, by using a non-1 scale, we really can
4515 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
4516 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
4518 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
4523 Amt = ConstantUInt::get(Type::UIntTy, Scale);
4524 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements))
4525 Amt = ConstantExpr::getMul(CI, cast<ConstantUInt>(Amt));
4526 else if (Scale != 1) {
4527 Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
4528 Amt = InsertNewInstBefore(Tmp, AI);
4532 if (unsigned Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
4533 Value *Off = ConstantUInt::get(Type::UIntTy, Offset);
4534 Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
4535 Amt = InsertNewInstBefore(Tmp, AI);
4538 std::string Name = AI.getName(); AI.setName("");
4539 AllocationInst *New;
4540 if (isa<MallocInst>(AI))
4541 New = new MallocInst(CastElTy, Amt, AI.getAlignment(), Name);
4543 New = new AllocaInst(CastElTy, Amt, AI.getAlignment(), Name);
4544 InsertNewInstBefore(New, AI);
4546 // If the allocation has multiple uses, insert a cast and change all things
4547 // that used it to use the new cast. This will also hack on CI, but it will
4549 if (!AI.hasOneUse()) {
4550 AddUsesToWorkList(AI);
4551 CastInst *NewCast = new CastInst(New, AI.getType(), "tmpcast");
4552 InsertNewInstBefore(NewCast, AI);
4553 AI.replaceAllUsesWith(NewCast);
4555 return ReplaceInstUsesWith(CI, New);
4559 // CastInst simplification
4561 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
4562 Value *Src = CI.getOperand(0);
4564 // If the user is casting a value to the same type, eliminate this cast
4566 if (CI.getType() == Src->getType())
4567 return ReplaceInstUsesWith(CI, Src);
4569 if (isa<UndefValue>(Src)) // cast undef -> undef
4570 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
4572 // If casting the result of another cast instruction, try to eliminate this
4575 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
4576 Value *A = CSrc->getOperand(0);
4577 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
4578 CI.getType(), TD)) {
4579 // This instruction now refers directly to the cast's src operand. This
4580 // has a good chance of making CSrc dead.
4581 CI.setOperand(0, CSrc->getOperand(0));
4585 // If this is an A->B->A cast, and we are dealing with integral types, try
4586 // to convert this into a logical 'and' instruction.
4588 if (A->getType()->isInteger() &&
4589 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
4590 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
4591 CSrc->getType()->getPrimitiveSizeInBits() <
4592 CI.getType()->getPrimitiveSizeInBits()&&
4593 A->getType()->getPrimitiveSizeInBits() ==
4594 CI.getType()->getPrimitiveSizeInBits()) {
4595 assert(CSrc->getType() != Type::ULongTy &&
4596 "Cannot have type bigger than ulong!");
4597 uint64_t AndValue = CSrc->getType()->getIntegralTypeMask();
4598 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
4600 AndOp = ConstantExpr::getCast(AndOp, A->getType());
4601 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
4602 if (And->getType() != CI.getType()) {
4603 And->setName(CSrc->getName()+".mask");
4604 InsertNewInstBefore(And, CI);
4605 And = new CastInst(And, CI.getType());
4611 // If this is a cast to bool, turn it into the appropriate setne instruction.
4612 if (CI.getType() == Type::BoolTy)
4613 return BinaryOperator::createSetNE(CI.getOperand(0),
4614 Constant::getNullValue(CI.getOperand(0)->getType()));
4616 // See if we can simplify any instructions used by the LHS whose sole
4617 // purpose is to compute bits we don't care about.
4618 if (CI.getType()->isInteger() && CI.getOperand(0)->getType()->isIntegral()) {
4619 uint64_t KnownZero, KnownOne;
4620 if (SimplifyDemandedBits(&CI, CI.getType()->getIntegralTypeMask(),
4621 KnownZero, KnownOne))
4625 // If casting the result of a getelementptr instruction with no offset, turn
4626 // this into a cast of the original pointer!
4628 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
4629 bool AllZeroOperands = true;
4630 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
4631 if (!isa<Constant>(GEP->getOperand(i)) ||
4632 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
4633 AllZeroOperands = false;
4636 if (AllZeroOperands) {
4637 CI.setOperand(0, GEP->getOperand(0));
4642 // If we are casting a malloc or alloca to a pointer to a type of the same
4643 // size, rewrite the allocation instruction to allocate the "right" type.
4645 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
4646 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
4649 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
4650 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
4652 if (isa<PHINode>(Src))
4653 if (Instruction *NV = FoldOpIntoPhi(CI))
4656 // If the source value is an instruction with only this use, we can attempt to
4657 // propagate the cast into the instruction. Also, only handle integral types
4659 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
4660 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
4661 CI.getType()->isInteger()) { // Don't mess with casts to bool here
4662 const Type *DestTy = CI.getType();
4663 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
4664 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
4666 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
4667 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
4669 switch (SrcI->getOpcode()) {
4670 case Instruction::Add:
4671 case Instruction::Mul:
4672 case Instruction::And:
4673 case Instruction::Or:
4674 case Instruction::Xor:
4675 // If we are discarding information, or just changing the sign, rewrite.
4676 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
4677 // Don't insert two casts if they cannot be eliminated. We allow two
4678 // casts to be inserted if the sizes are the same. This could only be
4679 // converting signedness, which is a noop.
4680 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
4681 !ValueRequiresCast(Op0, DestTy, TD)) {
4682 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4683 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
4684 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
4685 ->getOpcode(), Op0c, Op1c);
4689 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
4690 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
4691 Op1 == ConstantBool::True &&
4692 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
4693 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
4694 return BinaryOperator::createXor(New,
4695 ConstantInt::get(CI.getType(), 1));
4698 case Instruction::Shl:
4699 // Allow changing the sign of the source operand. Do not allow changing
4700 // the size of the shift, UNLESS the shift amount is a constant. We
4701 // mush not change variable sized shifts to a smaller size, because it
4702 // is undefined to shift more bits out than exist in the value.
4703 if (DestBitSize == SrcBitSize ||
4704 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
4705 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4706 return new ShiftInst(Instruction::Shl, Op0c, Op1);
4709 case Instruction::Shr:
4710 // If this is a signed shr, and if all bits shifted in are about to be
4711 // truncated off, turn it into an unsigned shr to allow greater
4713 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
4714 isa<ConstantInt>(Op1)) {
4715 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
4716 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
4717 // Convert to unsigned.
4718 Value *N1 = InsertOperandCastBefore(Op0,
4719 Op0->getType()->getUnsignedVersion(), &CI);
4720 // Insert the new shift, which is now unsigned.
4721 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
4722 Op1, Src->getName()), CI);
4723 return new CastInst(N1, CI.getType());
4728 case Instruction::SetNE:
4729 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4730 if (Op1C->getRawValue() == 0) {
4731 // If the input only has the low bit set, simplify directly.
4733 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4734 // cast (X != 0) to int --> X if X&~1 == 0
4735 if (MaskedValueIsZero(Op0,
4736 cast<ConstantIntegral>(Not1)->getZExtValue())) {
4737 if (CI.getType() == Op0->getType())
4738 return ReplaceInstUsesWith(CI, Op0);
4740 return new CastInst(Op0, CI.getType());
4743 // If the input is an and with a single bit, shift then simplify.
4744 ConstantInt *AndRHS;
4745 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
4746 if (AndRHS->getRawValue() &&
4747 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
4748 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
4749 // Perform an unsigned shr by shiftamt. Convert input to
4750 // unsigned if it is signed.
4752 if (In->getType()->isSigned())
4753 In = InsertNewInstBefore(new CastInst(In,
4754 In->getType()->getUnsignedVersion(), In->getName()),CI);
4755 // Insert the shift to put the result in the low bit.
4756 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
4757 ConstantInt::get(Type::UByteTy, ShiftAmt),
4758 In->getName()+".lobit"), CI);
4759 if (CI.getType() == In->getType())
4760 return ReplaceInstUsesWith(CI, In);
4762 return new CastInst(In, CI.getType());
4767 case Instruction::SetEQ:
4768 // We if we are just checking for a seteq of a single bit and casting it
4769 // to an integer. If so, shift the bit to the appropriate place then
4770 // cast to integer to avoid the comparison.
4771 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4772 // Is Op1C a power of two or zero?
4773 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
4774 // cast (X == 1) to int -> X iff X has only the low bit set.
4775 if (Op1C->getRawValue() == 1) {
4777 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4778 if (MaskedValueIsZero(Op0,
4779 cast<ConstantIntegral>(Not1)->getZExtValue())) {
4780 if (CI.getType() == Op0->getType())
4781 return ReplaceInstUsesWith(CI, Op0);
4783 return new CastInst(Op0, CI.getType());
4795 /// GetSelectFoldableOperands - We want to turn code that looks like this:
4797 /// %D = select %cond, %C, %A
4799 /// %C = select %cond, %B, 0
4802 /// Assuming that the specified instruction is an operand to the select, return
4803 /// a bitmask indicating which operands of this instruction are foldable if they
4804 /// equal the other incoming value of the select.
4806 static unsigned GetSelectFoldableOperands(Instruction *I) {
4807 switch (I->getOpcode()) {
4808 case Instruction::Add:
4809 case Instruction::Mul:
4810 case Instruction::And:
4811 case Instruction::Or:
4812 case Instruction::Xor:
4813 return 3; // Can fold through either operand.
4814 case Instruction::Sub: // Can only fold on the amount subtracted.
4815 case Instruction::Shl: // Can only fold on the shift amount.
4816 case Instruction::Shr:
4819 return 0; // Cannot fold
4823 /// GetSelectFoldableConstant - For the same transformation as the previous
4824 /// function, return the identity constant that goes into the select.
4825 static Constant *GetSelectFoldableConstant(Instruction *I) {
4826 switch (I->getOpcode()) {
4827 default: assert(0 && "This cannot happen!"); abort();
4828 case Instruction::Add:
4829 case Instruction::Sub:
4830 case Instruction::Or:
4831 case Instruction::Xor:
4832 return Constant::getNullValue(I->getType());
4833 case Instruction::Shl:
4834 case Instruction::Shr:
4835 return Constant::getNullValue(Type::UByteTy);
4836 case Instruction::And:
4837 return ConstantInt::getAllOnesValue(I->getType());
4838 case Instruction::Mul:
4839 return ConstantInt::get(I->getType(), 1);
4843 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
4844 /// have the same opcode and only one use each. Try to simplify this.
4845 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
4847 if (TI->getNumOperands() == 1) {
4848 // If this is a non-volatile load or a cast from the same type,
4850 if (TI->getOpcode() == Instruction::Cast) {
4851 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
4854 return 0; // unknown unary op.
4857 // Fold this by inserting a select from the input values.
4858 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
4859 FI->getOperand(0), SI.getName()+".v");
4860 InsertNewInstBefore(NewSI, SI);
4861 return new CastInst(NewSI, TI->getType());
4864 // Only handle binary operators here.
4865 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
4868 // Figure out if the operations have any operands in common.
4869 Value *MatchOp, *OtherOpT, *OtherOpF;
4871 if (TI->getOperand(0) == FI->getOperand(0)) {
4872 MatchOp = TI->getOperand(0);
4873 OtherOpT = TI->getOperand(1);
4874 OtherOpF = FI->getOperand(1);
4875 MatchIsOpZero = true;
4876 } else if (TI->getOperand(1) == FI->getOperand(1)) {
4877 MatchOp = TI->getOperand(1);
4878 OtherOpT = TI->getOperand(0);
4879 OtherOpF = FI->getOperand(0);
4880 MatchIsOpZero = false;
4881 } else if (!TI->isCommutative()) {
4883 } else if (TI->getOperand(0) == FI->getOperand(1)) {
4884 MatchOp = TI->getOperand(0);
4885 OtherOpT = TI->getOperand(1);
4886 OtherOpF = FI->getOperand(0);
4887 MatchIsOpZero = true;
4888 } else if (TI->getOperand(1) == FI->getOperand(0)) {
4889 MatchOp = TI->getOperand(1);
4890 OtherOpT = TI->getOperand(0);
4891 OtherOpF = FI->getOperand(1);
4892 MatchIsOpZero = true;
4897 // If we reach here, they do have operations in common.
4898 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4899 OtherOpF, SI.getName()+".v");
4900 InsertNewInstBefore(NewSI, SI);
4902 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4904 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4906 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4909 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4911 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4915 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4916 Value *CondVal = SI.getCondition();
4917 Value *TrueVal = SI.getTrueValue();
4918 Value *FalseVal = SI.getFalseValue();
4920 // select true, X, Y -> X
4921 // select false, X, Y -> Y
4922 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4923 if (C == ConstantBool::True)
4924 return ReplaceInstUsesWith(SI, TrueVal);
4926 assert(C == ConstantBool::False);
4927 return ReplaceInstUsesWith(SI, FalseVal);
4930 // select C, X, X -> X
4931 if (TrueVal == FalseVal)
4932 return ReplaceInstUsesWith(SI, TrueVal);
4934 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4935 return ReplaceInstUsesWith(SI, FalseVal);
4936 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4937 return ReplaceInstUsesWith(SI, TrueVal);
4938 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4939 if (isa<Constant>(TrueVal))
4940 return ReplaceInstUsesWith(SI, TrueVal);
4942 return ReplaceInstUsesWith(SI, FalseVal);
4945 if (SI.getType() == Type::BoolTy)
4946 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4947 if (C == ConstantBool::True) {
4948 // Change: A = select B, true, C --> A = or B, C
4949 return BinaryOperator::createOr(CondVal, FalseVal);
4951 // Change: A = select B, false, C --> A = and !B, C
4953 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4954 "not."+CondVal->getName()), SI);
4955 return BinaryOperator::createAnd(NotCond, FalseVal);
4957 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4958 if (C == ConstantBool::False) {
4959 // Change: A = select B, C, false --> A = and B, C
4960 return BinaryOperator::createAnd(CondVal, TrueVal);
4962 // Change: A = select B, C, true --> A = or !B, C
4964 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4965 "not."+CondVal->getName()), SI);
4966 return BinaryOperator::createOr(NotCond, TrueVal);
4970 // Selecting between two integer constants?
4971 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4972 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4973 // select C, 1, 0 -> cast C to int
4974 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4975 return new CastInst(CondVal, SI.getType());
4976 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4977 // select C, 0, 1 -> cast !C to int
4979 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4980 "not."+CondVal->getName()), SI);
4981 return new CastInst(NotCond, SI.getType());
4984 // If one of the constants is zero (we know they can't both be) and we
4985 // have a setcc instruction with zero, and we have an 'and' with the
4986 // non-constant value, eliminate this whole mess. This corresponds to
4987 // cases like this: ((X & 27) ? 27 : 0)
4988 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4989 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4990 if ((IC->getOpcode() == Instruction::SetEQ ||
4991 IC->getOpcode() == Instruction::SetNE) &&
4992 isa<ConstantInt>(IC->getOperand(1)) &&
4993 cast<Constant>(IC->getOperand(1))->isNullValue())
4994 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4995 if (ICA->getOpcode() == Instruction::And &&
4996 isa<ConstantInt>(ICA->getOperand(1)) &&
4997 (ICA->getOperand(1) == TrueValC ||
4998 ICA->getOperand(1) == FalseValC) &&
4999 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
5000 // Okay, now we know that everything is set up, we just don't
5001 // know whether we have a setne or seteq and whether the true or
5002 // false val is the zero.
5003 bool ShouldNotVal = !TrueValC->isNullValue();
5004 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
5007 V = InsertNewInstBefore(BinaryOperator::create(
5008 Instruction::Xor, V, ICA->getOperand(1)), SI);
5009 return ReplaceInstUsesWith(SI, V);
5013 // See if we are selecting two values based on a comparison of the two values.
5014 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
5015 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
5016 // Transform (X == Y) ? X : Y -> Y
5017 if (SCI->getOpcode() == Instruction::SetEQ)
5018 return ReplaceInstUsesWith(SI, FalseVal);
5019 // Transform (X != Y) ? X : Y -> X
5020 if (SCI->getOpcode() == Instruction::SetNE)
5021 return ReplaceInstUsesWith(SI, TrueVal);
5022 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
5024 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
5025 // Transform (X == Y) ? Y : X -> X
5026 if (SCI->getOpcode() == Instruction::SetEQ)
5027 return ReplaceInstUsesWith(SI, FalseVal);
5028 // Transform (X != Y) ? Y : X -> Y
5029 if (SCI->getOpcode() == Instruction::SetNE)
5030 return ReplaceInstUsesWith(SI, TrueVal);
5031 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
5035 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
5036 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
5037 if (TI->hasOneUse() && FI->hasOneUse()) {
5038 bool isInverse = false;
5039 Instruction *AddOp = 0, *SubOp = 0;
5041 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
5042 if (TI->getOpcode() == FI->getOpcode())
5043 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
5046 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
5047 // even legal for FP.
5048 if (TI->getOpcode() == Instruction::Sub &&
5049 FI->getOpcode() == Instruction::Add) {
5050 AddOp = FI; SubOp = TI;
5051 } else if (FI->getOpcode() == Instruction::Sub &&
5052 TI->getOpcode() == Instruction::Add) {
5053 AddOp = TI; SubOp = FI;
5057 Value *OtherAddOp = 0;
5058 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
5059 OtherAddOp = AddOp->getOperand(1);
5060 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
5061 OtherAddOp = AddOp->getOperand(0);
5065 // So at this point we know we have:
5066 // select C, (add X, Y), (sub X, ?)
5067 // We can do the transform profitably if either 'Y' = '?' or '?' is
5069 if (SubOp->getOperand(1) == AddOp ||
5070 isa<Constant>(SubOp->getOperand(1))) {
5072 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
5073 NegVal = ConstantExpr::getNeg(C);
5075 NegVal = InsertNewInstBefore(
5076 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
5079 Value *NewTrueOp = OtherAddOp;
5080 Value *NewFalseOp = NegVal;
5082 std::swap(NewTrueOp, NewFalseOp);
5083 Instruction *NewSel =
5084 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
5086 NewSel = InsertNewInstBefore(NewSel, SI);
5087 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
5093 // See if we can fold the select into one of our operands.
5094 if (SI.getType()->isInteger()) {
5095 // See the comment above GetSelectFoldableOperands for a description of the
5096 // transformation we are doing here.
5097 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
5098 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
5099 !isa<Constant>(FalseVal))
5100 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
5101 unsigned OpToFold = 0;
5102 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
5104 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
5109 Constant *C = GetSelectFoldableConstant(TVI);
5110 std::string Name = TVI->getName(); TVI->setName("");
5111 Instruction *NewSel =
5112 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
5114 InsertNewInstBefore(NewSel, SI);
5115 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
5116 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
5117 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
5118 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
5120 assert(0 && "Unknown instruction!!");
5125 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
5126 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
5127 !isa<Constant>(TrueVal))
5128 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
5129 unsigned OpToFold = 0;
5130 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
5132 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
5137 Constant *C = GetSelectFoldableConstant(FVI);
5138 std::string Name = FVI->getName(); FVI->setName("");
5139 Instruction *NewSel =
5140 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
5142 InsertNewInstBefore(NewSel, SI);
5143 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
5144 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
5145 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
5146 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
5148 assert(0 && "Unknown instruction!!");
5154 if (BinaryOperator::isNot(CondVal)) {
5155 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
5156 SI.setOperand(1, FalseVal);
5157 SI.setOperand(2, TrueVal);
5165 /// visitCallInst - CallInst simplification. This mostly only handles folding
5166 /// of intrinsic instructions. For normal calls, it allows visitCallSite to do
5167 /// the heavy lifting.
5169 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
5170 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
5171 if (!II) return visitCallSite(&CI);
5173 // Intrinsics cannot occur in an invoke, so handle them here instead of in
5175 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
5176 bool Changed = false;
5178 // memmove/cpy/set of zero bytes is a noop.
5179 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
5180 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
5182 // FIXME: Increase alignment here.
5184 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
5185 if (CI->getRawValue() == 1) {
5186 // Replace the instruction with just byte operations. We would
5187 // transform other cases to loads/stores, but we don't know if
5188 // alignment is sufficient.
5192 // If we have a memmove and the source operation is a constant global,
5193 // then the source and dest pointers can't alias, so we can change this
5194 // into a call to memcpy.
5195 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(II))
5196 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
5197 if (GVSrc->isConstant()) {
5198 Module *M = CI.getParent()->getParent()->getParent();
5199 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
5200 CI.getCalledFunction()->getFunctionType());
5201 CI.setOperand(0, MemCpy);
5205 if (Changed) return II;
5206 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(II)) {
5207 // If this stoppoint is at the same source location as the previous
5208 // stoppoint in the chain, it is not needed.
5209 if (DbgStopPointInst *PrevSPI =
5210 dyn_cast<DbgStopPointInst>(SPI->getChain()))
5211 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
5212 SPI->getColNo() == PrevSPI->getColNo()) {
5213 SPI->replaceAllUsesWith(PrevSPI);
5214 return EraseInstFromFunction(CI);
5217 switch (II->getIntrinsicID()) {
5219 case Intrinsic::stackrestore: {
5220 // If the save is right next to the restore, remove the restore. This can
5221 // happen when variable allocas are DCE'd.
5222 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
5223 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
5224 BasicBlock::iterator BI = SS;
5226 return EraseInstFromFunction(CI);
5230 // If the stack restore is in a return/unwind block and if there are no
5231 // allocas or calls between the restore and the return, nuke the restore.
5232 TerminatorInst *TI = II->getParent()->getTerminator();
5233 if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) {
5234 BasicBlock::iterator BI = II;
5235 bool CannotRemove = false;
5236 for (++BI; &*BI != TI; ++BI) {
5237 if (isa<AllocaInst>(BI) ||
5238 (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) {
5239 CannotRemove = true;
5244 return EraseInstFromFunction(CI);
5251 return visitCallSite(II);
5254 // InvokeInst simplification
5256 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
5257 return visitCallSite(&II);
5260 // visitCallSite - Improvements for call and invoke instructions.
5262 Instruction *InstCombiner::visitCallSite(CallSite CS) {
5263 bool Changed = false;
5265 // If the callee is a constexpr cast of a function, attempt to move the cast
5266 // to the arguments of the call/invoke.
5267 if (transformConstExprCastCall(CS)) return 0;
5269 Value *Callee = CS.getCalledValue();
5271 if (Function *CalleeF = dyn_cast<Function>(Callee))
5272 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
5273 Instruction *OldCall = CS.getInstruction();
5274 // If the call and callee calling conventions don't match, this call must
5275 // be unreachable, as the call is undefined.
5276 new StoreInst(ConstantBool::True,
5277 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
5278 if (!OldCall->use_empty())
5279 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
5280 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
5281 return EraseInstFromFunction(*OldCall);
5285 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
5286 // This instruction is not reachable, just remove it. We insert a store to
5287 // undef so that we know that this code is not reachable, despite the fact
5288 // that we can't modify the CFG here.
5289 new StoreInst(ConstantBool::True,
5290 UndefValue::get(PointerType::get(Type::BoolTy)),
5291 CS.getInstruction());
5293 if (!CS.getInstruction()->use_empty())
5294 CS.getInstruction()->
5295 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
5297 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
5298 // Don't break the CFG, insert a dummy cond branch.
5299 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
5300 ConstantBool::True, II);
5302 return EraseInstFromFunction(*CS.getInstruction());
5305 const PointerType *PTy = cast<PointerType>(Callee->getType());
5306 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
5307 if (FTy->isVarArg()) {
5308 // See if we can optimize any arguments passed through the varargs area of
5310 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
5311 E = CS.arg_end(); I != E; ++I)
5312 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
5313 // If this cast does not effect the value passed through the varargs
5314 // area, we can eliminate the use of the cast.
5315 Value *Op = CI->getOperand(0);
5316 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
5323 return Changed ? CS.getInstruction() : 0;
5326 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
5327 // attempt to move the cast to the arguments of the call/invoke.
5329 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
5330 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
5331 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
5332 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
5334 Function *Callee = cast<Function>(CE->getOperand(0));
5335 Instruction *Caller = CS.getInstruction();
5337 // Okay, this is a cast from a function to a different type. Unless doing so
5338 // would cause a type conversion of one of our arguments, change this call to
5339 // be a direct call with arguments casted to the appropriate types.
5341 const FunctionType *FT = Callee->getFunctionType();
5342 const Type *OldRetTy = Caller->getType();
5344 // Check to see if we are changing the return type...
5345 if (OldRetTy != FT->getReturnType()) {
5346 if (Callee->isExternal() &&
5347 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
5348 !Caller->use_empty())
5349 return false; // Cannot transform this return value...
5351 // If the callsite is an invoke instruction, and the return value is used by
5352 // a PHI node in a successor, we cannot change the return type of the call
5353 // because there is no place to put the cast instruction (without breaking
5354 // the critical edge). Bail out in this case.
5355 if (!Caller->use_empty())
5356 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
5357 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
5359 if (PHINode *PN = dyn_cast<PHINode>(*UI))
5360 if (PN->getParent() == II->getNormalDest() ||
5361 PN->getParent() == II->getUnwindDest())
5365 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
5366 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
5368 CallSite::arg_iterator AI = CS.arg_begin();
5369 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
5370 const Type *ParamTy = FT->getParamType(i);
5371 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
5372 if (Callee->isExternal() && !isConvertible) return false;
5375 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
5376 Callee->isExternal())
5377 return false; // Do not delete arguments unless we have a function body...
5379 // Okay, we decided that this is a safe thing to do: go ahead and start
5380 // inserting cast instructions as necessary...
5381 std::vector<Value*> Args;
5382 Args.reserve(NumActualArgs);
5384 AI = CS.arg_begin();
5385 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
5386 const Type *ParamTy = FT->getParamType(i);
5387 if ((*AI)->getType() == ParamTy) {
5388 Args.push_back(*AI);
5390 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
5395 // If the function takes more arguments than the call was taking, add them
5397 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
5398 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
5400 // If we are removing arguments to the function, emit an obnoxious warning...
5401 if (FT->getNumParams() < NumActualArgs)
5402 if (!FT->isVarArg()) {
5403 std::cerr << "WARNING: While resolving call to function '"
5404 << Callee->getName() << "' arguments were dropped!\n";
5406 // Add all of the arguments in their promoted form to the arg list...
5407 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
5408 const Type *PTy = getPromotedType((*AI)->getType());
5409 if (PTy != (*AI)->getType()) {
5410 // Must promote to pass through va_arg area!
5411 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
5412 InsertNewInstBefore(Cast, *Caller);
5413 Args.push_back(Cast);
5415 Args.push_back(*AI);
5420 if (FT->getReturnType() == Type::VoidTy)
5421 Caller->setName(""); // Void type should not have a name...
5424 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
5425 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
5426 Args, Caller->getName(), Caller);
5427 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
5429 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
5430 if (cast<CallInst>(Caller)->isTailCall())
5431 cast<CallInst>(NC)->setTailCall();
5432 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
5435 // Insert a cast of the return type as necessary...
5437 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
5438 if (NV->getType() != Type::VoidTy) {
5439 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
5441 // If this is an invoke instruction, we should insert it after the first
5442 // non-phi, instruction in the normal successor block.
5443 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
5444 BasicBlock::iterator I = II->getNormalDest()->begin();
5445 while (isa<PHINode>(I)) ++I;
5446 InsertNewInstBefore(NC, *I);
5448 // Otherwise, it's a call, just insert cast right after the call instr
5449 InsertNewInstBefore(NC, *Caller);
5451 AddUsersToWorkList(*Caller);
5453 NV = UndefValue::get(Caller->getType());
5457 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
5458 Caller->replaceAllUsesWith(NV);
5459 Caller->getParent()->getInstList().erase(Caller);
5460 removeFromWorkList(Caller);
5465 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
5466 // operator and they all are only used by the PHI, PHI together their
5467 // inputs, and do the operation once, to the result of the PHI.
5468 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
5469 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
5471 // Scan the instruction, looking for input operations that can be folded away.
5472 // If all input operands to the phi are the same instruction (e.g. a cast from
5473 // the same type or "+42") we can pull the operation through the PHI, reducing
5474 // code size and simplifying code.
5475 Constant *ConstantOp = 0;
5476 const Type *CastSrcTy = 0;
5477 if (isa<CastInst>(FirstInst)) {
5478 CastSrcTy = FirstInst->getOperand(0)->getType();
5479 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
5480 // Can fold binop or shift if the RHS is a constant.
5481 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
5482 if (ConstantOp == 0) return 0;
5484 return 0; // Cannot fold this operation.
5487 // Check to see if all arguments are the same operation.
5488 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
5489 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
5490 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
5491 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
5494 if (I->getOperand(0)->getType() != CastSrcTy)
5495 return 0; // Cast operation must match.
5496 } else if (I->getOperand(1) != ConstantOp) {
5501 // Okay, they are all the same operation. Create a new PHI node of the
5502 // correct type, and PHI together all of the LHS's of the instructions.
5503 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
5504 PN.getName()+".in");
5505 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
5507 Value *InVal = FirstInst->getOperand(0);
5508 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
5510 // Add all operands to the new PHI.
5511 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
5512 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
5513 if (NewInVal != InVal)
5515 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
5520 // The new PHI unions all of the same values together. This is really
5521 // common, so we handle it intelligently here for compile-time speed.
5525 InsertNewInstBefore(NewPN, PN);
5529 // Insert and return the new operation.
5530 if (isa<CastInst>(FirstInst))
5531 return new CastInst(PhiVal, PN.getType());
5532 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
5533 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
5535 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
5536 PhiVal, ConstantOp);
5539 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
5541 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
5542 if (PN->use_empty()) return true;
5543 if (!PN->hasOneUse()) return false;
5545 // Remember this node, and if we find the cycle, return.
5546 if (!PotentiallyDeadPHIs.insert(PN).second)
5549 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
5550 return DeadPHICycle(PU, PotentiallyDeadPHIs);
5555 // PHINode simplification
5557 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
5558 if (Value *V = PN.hasConstantValue())
5559 return ReplaceInstUsesWith(PN, V);
5561 // If the only user of this instruction is a cast instruction, and all of the
5562 // incoming values are constants, change this PHI to merge together the casted
5565 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
5566 if (CI->getType() != PN.getType()) { // noop casts will be folded
5567 bool AllConstant = true;
5568 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
5569 if (!isa<Constant>(PN.getIncomingValue(i))) {
5570 AllConstant = false;
5574 // Make a new PHI with all casted values.
5575 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
5576 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
5577 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
5578 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
5579 PN.getIncomingBlock(i));
5582 // Update the cast instruction.
5583 CI->setOperand(0, New);
5584 WorkList.push_back(CI); // revisit the cast instruction to fold.
5585 WorkList.push_back(New); // Make sure to revisit the new Phi
5586 return &PN; // PN is now dead!
5590 // If all PHI operands are the same operation, pull them through the PHI,
5591 // reducing code size.
5592 if (isa<Instruction>(PN.getIncomingValue(0)) &&
5593 PN.getIncomingValue(0)->hasOneUse())
5594 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
5597 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
5598 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
5599 // PHI)... break the cycle.
5601 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
5602 std::set<PHINode*> PotentiallyDeadPHIs;
5603 PotentiallyDeadPHIs.insert(&PN);
5604 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
5605 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
5611 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
5612 Instruction *InsertPoint,
5614 unsigned PS = IC->getTargetData().getPointerSize();
5615 const Type *VTy = V->getType();
5616 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
5617 // We must insert a cast to ensure we sign-extend.
5618 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
5619 V->getName()), *InsertPoint);
5620 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
5625 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
5626 Value *PtrOp = GEP.getOperand(0);
5627 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
5628 // If so, eliminate the noop.
5629 if (GEP.getNumOperands() == 1)
5630 return ReplaceInstUsesWith(GEP, PtrOp);
5632 if (isa<UndefValue>(GEP.getOperand(0)))
5633 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
5635 bool HasZeroPointerIndex = false;
5636 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
5637 HasZeroPointerIndex = C->isNullValue();
5639 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
5640 return ReplaceInstUsesWith(GEP, PtrOp);
5642 // Eliminate unneeded casts for indices.
5643 bool MadeChange = false;
5644 gep_type_iterator GTI = gep_type_begin(GEP);
5645 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
5646 if (isa<SequentialType>(*GTI)) {
5647 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
5648 Value *Src = CI->getOperand(0);
5649 const Type *SrcTy = Src->getType();
5650 const Type *DestTy = CI->getType();
5651 if (Src->getType()->isInteger()) {
5652 if (SrcTy->getPrimitiveSizeInBits() ==
5653 DestTy->getPrimitiveSizeInBits()) {
5654 // We can always eliminate a cast from ulong or long to the other.
5655 // We can always eliminate a cast from uint to int or the other on
5656 // 32-bit pointer platforms.
5657 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
5659 GEP.setOperand(i, Src);
5661 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
5662 SrcTy->getPrimitiveSize() == 4) {
5663 // We can always eliminate a cast from int to [u]long. We can
5664 // eliminate a cast from uint to [u]long iff the target is a 32-bit
5666 if (SrcTy->isSigned() ||
5667 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
5669 GEP.setOperand(i, Src);
5674 // If we are using a wider index than needed for this platform, shrink it
5675 // to what we need. If the incoming value needs a cast instruction,
5676 // insert it. This explicit cast can make subsequent optimizations more
5678 Value *Op = GEP.getOperand(i);
5679 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
5680 if (Constant *C = dyn_cast<Constant>(Op)) {
5681 GEP.setOperand(i, ConstantExpr::getCast(C,
5682 TD->getIntPtrType()->getSignedVersion()));
5685 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
5686 Op->getName()), GEP);
5687 GEP.setOperand(i, Op);
5691 // If this is a constant idx, make sure to canonicalize it to be a signed
5692 // operand, otherwise CSE and other optimizations are pessimized.
5693 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
5694 GEP.setOperand(i, ConstantExpr::getCast(CUI,
5695 CUI->getType()->getSignedVersion()));
5699 if (MadeChange) return &GEP;
5701 // Combine Indices - If the source pointer to this getelementptr instruction
5702 // is a getelementptr instruction, combine the indices of the two
5703 // getelementptr instructions into a single instruction.
5705 std::vector<Value*> SrcGEPOperands;
5706 if (User *Src = dyn_castGetElementPtr(PtrOp))
5707 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
5709 if (!SrcGEPOperands.empty()) {
5710 // Note that if our source is a gep chain itself that we wait for that
5711 // chain to be resolved before we perform this transformation. This
5712 // avoids us creating a TON of code in some cases.
5714 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
5715 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
5716 return 0; // Wait until our source is folded to completion.
5718 std::vector<Value *> Indices;
5720 // Find out whether the last index in the source GEP is a sequential idx.
5721 bool EndsWithSequential = false;
5722 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
5723 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
5724 EndsWithSequential = !isa<StructType>(*I);
5726 // Can we combine the two pointer arithmetics offsets?
5727 if (EndsWithSequential) {
5728 // Replace: gep (gep %P, long B), long A, ...
5729 // With: T = long A+B; gep %P, T, ...
5731 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
5732 if (SO1 == Constant::getNullValue(SO1->getType())) {
5734 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
5737 // If they aren't the same type, convert both to an integer of the
5738 // target's pointer size.
5739 if (SO1->getType() != GO1->getType()) {
5740 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
5741 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
5742 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
5743 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
5745 unsigned PS = TD->getPointerSize();
5746 if (SO1->getType()->getPrimitiveSize() == PS) {
5747 // Convert GO1 to SO1's type.
5748 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
5750 } else if (GO1->getType()->getPrimitiveSize() == PS) {
5751 // Convert SO1 to GO1's type.
5752 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
5754 const Type *PT = TD->getIntPtrType();
5755 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
5756 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
5760 if (isa<Constant>(SO1) && isa<Constant>(GO1))
5761 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
5763 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
5764 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
5768 // Recycle the GEP we already have if possible.
5769 if (SrcGEPOperands.size() == 2) {
5770 GEP.setOperand(0, SrcGEPOperands[0]);
5771 GEP.setOperand(1, Sum);
5774 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5775 SrcGEPOperands.end()-1);
5776 Indices.push_back(Sum);
5777 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
5779 } else if (isa<Constant>(*GEP.idx_begin()) &&
5780 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
5781 SrcGEPOperands.size() != 1) {
5782 // Otherwise we can do the fold if the first index of the GEP is a zero
5783 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5784 SrcGEPOperands.end());
5785 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
5788 if (!Indices.empty())
5789 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
5791 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
5792 // GEP of global variable. If all of the indices for this GEP are
5793 // constants, we can promote this to a constexpr instead of an instruction.
5795 // Scan for nonconstants...
5796 std::vector<Constant*> Indices;
5797 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
5798 for (; I != E && isa<Constant>(*I); ++I)
5799 Indices.push_back(cast<Constant>(*I));
5801 if (I == E) { // If they are all constants...
5802 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
5804 // Replace all uses of the GEP with the new constexpr...
5805 return ReplaceInstUsesWith(GEP, CE);
5807 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
5808 if (!isa<PointerType>(X->getType())) {
5809 // Not interesting. Source pointer must be a cast from pointer.
5810 } else if (HasZeroPointerIndex) {
5811 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
5812 // into : GEP [10 x ubyte]* X, long 0, ...
5814 // This occurs when the program declares an array extern like "int X[];"
5816 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
5817 const PointerType *XTy = cast<PointerType>(X->getType());
5818 if (const ArrayType *XATy =
5819 dyn_cast<ArrayType>(XTy->getElementType()))
5820 if (const ArrayType *CATy =
5821 dyn_cast<ArrayType>(CPTy->getElementType()))
5822 if (CATy->getElementType() == XATy->getElementType()) {
5823 // At this point, we know that the cast source type is a pointer
5824 // to an array of the same type as the destination pointer
5825 // array. Because the array type is never stepped over (there
5826 // is a leading zero) we can fold the cast into this GEP.
5827 GEP.setOperand(0, X);
5830 } else if (GEP.getNumOperands() == 2) {
5831 // Transform things like:
5832 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
5833 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
5834 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
5835 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
5836 if (isa<ArrayType>(SrcElTy) &&
5837 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
5838 TD->getTypeSize(ResElTy)) {
5839 Value *V = InsertNewInstBefore(
5840 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5841 GEP.getOperand(1), GEP.getName()), GEP);
5842 return new CastInst(V, GEP.getType());
5845 // Transform things like:
5846 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
5847 // (where tmp = 8*tmp2) into:
5848 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
5850 if (isa<ArrayType>(SrcElTy) &&
5851 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
5852 uint64_t ArrayEltSize =
5853 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
5855 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
5856 // allow either a mul, shift, or constant here.
5858 ConstantInt *Scale = 0;
5859 if (ArrayEltSize == 1) {
5860 NewIdx = GEP.getOperand(1);
5861 Scale = ConstantInt::get(NewIdx->getType(), 1);
5862 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
5863 NewIdx = ConstantInt::get(CI->getType(), 1);
5865 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
5866 if (Inst->getOpcode() == Instruction::Shl &&
5867 isa<ConstantInt>(Inst->getOperand(1))) {
5868 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
5869 if (Inst->getType()->isSigned())
5870 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
5872 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
5873 NewIdx = Inst->getOperand(0);
5874 } else if (Inst->getOpcode() == Instruction::Mul &&
5875 isa<ConstantInt>(Inst->getOperand(1))) {
5876 Scale = cast<ConstantInt>(Inst->getOperand(1));
5877 NewIdx = Inst->getOperand(0);
5881 // If the index will be to exactly the right offset with the scale taken
5882 // out, perform the transformation.
5883 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
5884 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
5885 Scale = ConstantSInt::get(C->getType(),
5886 (int64_t)C->getRawValue() /
5887 (int64_t)ArrayEltSize);
5889 Scale = ConstantUInt::get(Scale->getType(),
5890 Scale->getRawValue() / ArrayEltSize);
5891 if (Scale->getRawValue() != 1) {
5892 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
5893 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
5894 NewIdx = InsertNewInstBefore(Sc, GEP);
5897 // Insert the new GEP instruction.
5899 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5900 NewIdx, GEP.getName());
5901 Idx = InsertNewInstBefore(Idx, GEP);
5902 return new CastInst(Idx, GEP.getType());
5911 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
5912 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
5913 if (AI.isArrayAllocation()) // Check C != 1
5914 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
5915 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
5916 AllocationInst *New = 0;
5918 // Create and insert the replacement instruction...
5919 if (isa<MallocInst>(AI))
5920 New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
5922 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
5923 New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
5926 InsertNewInstBefore(New, AI);
5928 // Scan to the end of the allocation instructions, to skip over a block of
5929 // allocas if possible...
5931 BasicBlock::iterator It = New;
5932 while (isa<AllocationInst>(*It)) ++It;
5934 // Now that I is pointing to the first non-allocation-inst in the block,
5935 // insert our getelementptr instruction...
5937 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5938 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5939 New->getName()+".sub", It);
5941 // Now make everything use the getelementptr instead of the original
5943 return ReplaceInstUsesWith(AI, V);
5944 } else if (isa<UndefValue>(AI.getArraySize())) {
5945 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5948 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5949 // Note that we only do this for alloca's, because malloc should allocate and
5950 // return a unique pointer, even for a zero byte allocation.
5951 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5952 TD->getTypeSize(AI.getAllocatedType()) == 0)
5953 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5958 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5959 Value *Op = FI.getOperand(0);
5961 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5962 if (CastInst *CI = dyn_cast<CastInst>(Op))
5963 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5964 FI.setOperand(0, CI->getOperand(0));
5968 // free undef -> unreachable.
5969 if (isa<UndefValue>(Op)) {
5970 // Insert a new store to null because we cannot modify the CFG here.
5971 new StoreInst(ConstantBool::True,
5972 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5973 return EraseInstFromFunction(FI);
5976 // If we have 'free null' delete the instruction. This can happen in stl code
5977 // when lots of inlining happens.
5978 if (isa<ConstantPointerNull>(Op))
5979 return EraseInstFromFunction(FI);
5985 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5986 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5987 User *CI = cast<User>(LI.getOperand(0));
5988 Value *CastOp = CI->getOperand(0);
5990 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5991 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5992 const Type *SrcPTy = SrcTy->getElementType();
5994 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5995 // If the source is an array, the code below will not succeed. Check to
5996 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5998 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5999 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
6000 if (ASrcTy->getNumElements() != 0) {
6001 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
6002 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
6003 SrcTy = cast<PointerType>(CastOp->getType());
6004 SrcPTy = SrcTy->getElementType();
6007 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
6008 // Do not allow turning this into a load of an integer, which is then
6009 // casted to a pointer, this pessimizes pointer analysis a lot.
6010 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
6011 IC.getTargetData().getTypeSize(SrcPTy) ==
6012 IC.getTargetData().getTypeSize(DestPTy)) {
6014 // Okay, we are casting from one integer or pointer type to another of
6015 // the same size. Instead of casting the pointer before the load, cast
6016 // the result of the loaded value.
6017 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
6019 LI.isVolatile()),LI);
6020 // Now cast the result of the load.
6021 return new CastInst(NewLoad, LI.getType());
6028 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
6029 /// from this value cannot trap. If it is not obviously safe to load from the
6030 /// specified pointer, we do a quick local scan of the basic block containing
6031 /// ScanFrom, to determine if the address is already accessed.
6032 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
6033 // If it is an alloca or global variable, it is always safe to load from.
6034 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
6036 // Otherwise, be a little bit agressive by scanning the local block where we
6037 // want to check to see if the pointer is already being loaded or stored
6038 // from/to. If so, the previous load or store would have already trapped,
6039 // so there is no harm doing an extra load (also, CSE will later eliminate
6040 // the load entirely).
6041 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
6046 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
6047 if (LI->getOperand(0) == V) return true;
6048 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
6049 if (SI->getOperand(1) == V) return true;
6055 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
6056 Value *Op = LI.getOperand(0);
6058 // load (cast X) --> cast (load X) iff safe
6059 if (CastInst *CI = dyn_cast<CastInst>(Op))
6060 if (Instruction *Res = InstCombineLoadCast(*this, LI))
6063 // None of the following transforms are legal for volatile loads.
6064 if (LI.isVolatile()) return 0;
6066 if (&LI.getParent()->front() != &LI) {
6067 BasicBlock::iterator BBI = &LI; --BBI;
6068 // If the instruction immediately before this is a store to the same
6069 // address, do a simple form of store->load forwarding.
6070 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
6071 if (SI->getOperand(1) == LI.getOperand(0))
6072 return ReplaceInstUsesWith(LI, SI->getOperand(0));
6073 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
6074 if (LIB->getOperand(0) == LI.getOperand(0))
6075 return ReplaceInstUsesWith(LI, LIB);
6078 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
6079 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
6080 isa<UndefValue>(GEPI->getOperand(0))) {
6081 // Insert a new store to null instruction before the load to indicate
6082 // that this code is not reachable. We do this instead of inserting
6083 // an unreachable instruction directly because we cannot modify the
6085 new StoreInst(UndefValue::get(LI.getType()),
6086 Constant::getNullValue(Op->getType()), &LI);
6087 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
6090 if (Constant *C = dyn_cast<Constant>(Op)) {
6091 // load null/undef -> undef
6092 if ((C->isNullValue() || isa<UndefValue>(C))) {
6093 // Insert a new store to null instruction before the load to indicate that
6094 // this code is not reachable. We do this instead of inserting an
6095 // unreachable instruction directly because we cannot modify the CFG.
6096 new StoreInst(UndefValue::get(LI.getType()),
6097 Constant::getNullValue(Op->getType()), &LI);
6098 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
6101 // Instcombine load (constant global) into the value loaded.
6102 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
6103 if (GV->isConstant() && !GV->isExternal())
6104 return ReplaceInstUsesWith(LI, GV->getInitializer());
6106 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
6107 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
6108 if (CE->getOpcode() == Instruction::GetElementPtr) {
6109 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
6110 if (GV->isConstant() && !GV->isExternal())
6112 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
6113 return ReplaceInstUsesWith(LI, V);
6114 if (CE->getOperand(0)->isNullValue()) {
6115 // Insert a new store to null instruction before the load to indicate
6116 // that this code is not reachable. We do this instead of inserting
6117 // an unreachable instruction directly because we cannot modify the
6119 new StoreInst(UndefValue::get(LI.getType()),
6120 Constant::getNullValue(Op->getType()), &LI);
6121 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
6124 } else if (CE->getOpcode() == Instruction::Cast) {
6125 if (Instruction *Res = InstCombineLoadCast(*this, LI))
6130 if (Op->hasOneUse()) {
6131 // Change select and PHI nodes to select values instead of addresses: this
6132 // helps alias analysis out a lot, allows many others simplifications, and
6133 // exposes redundancy in the code.
6135 // Note that we cannot do the transformation unless we know that the
6136 // introduced loads cannot trap! Something like this is valid as long as
6137 // the condition is always false: load (select bool %C, int* null, int* %G),
6138 // but it would not be valid if we transformed it to load from null
6141 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
6142 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
6143 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
6144 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
6145 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
6146 SI->getOperand(1)->getName()+".val"), LI);
6147 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
6148 SI->getOperand(2)->getName()+".val"), LI);
6149 return new SelectInst(SI->getCondition(), V1, V2);
6152 // load (select (cond, null, P)) -> load P
6153 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
6154 if (C->isNullValue()) {
6155 LI.setOperand(0, SI->getOperand(2));
6159 // load (select (cond, P, null)) -> load P
6160 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
6161 if (C->isNullValue()) {
6162 LI.setOperand(0, SI->getOperand(1));
6166 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
6167 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
6168 bool Safe = PN->getParent() == LI.getParent();
6170 // Scan all of the instructions between the PHI and the load to make
6171 // sure there are no instructions that might possibly alter the value
6172 // loaded from the PHI.
6174 BasicBlock::iterator I = &LI;
6175 for (--I; !isa<PHINode>(I); --I)
6176 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
6182 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
6183 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
6184 PN->getIncomingBlock(i)->getTerminator()))
6189 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
6190 InsertNewInstBefore(NewPN, *PN);
6191 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
6193 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
6194 BasicBlock *BB = PN->getIncomingBlock(i);
6195 Value *&TheLoad = LoadMap[BB];
6197 Value *InVal = PN->getIncomingValue(i);
6198 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
6199 InVal->getName()+".val"),
6200 *BB->getTerminator());
6202 NewPN->addIncoming(TheLoad, BB);
6204 return ReplaceInstUsesWith(LI, NewPN);
6211 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
6213 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
6214 User *CI = cast<User>(SI.getOperand(1));
6215 Value *CastOp = CI->getOperand(0);
6217 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
6218 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
6219 const Type *SrcPTy = SrcTy->getElementType();
6221 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
6222 // If the source is an array, the code below will not succeed. Check to
6223 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
6225 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
6226 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
6227 if (ASrcTy->getNumElements() != 0) {
6228 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
6229 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
6230 SrcTy = cast<PointerType>(CastOp->getType());
6231 SrcPTy = SrcTy->getElementType();
6234 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
6235 IC.getTargetData().getTypeSize(SrcPTy) ==
6236 IC.getTargetData().getTypeSize(DestPTy)) {
6238 // Okay, we are casting from one integer or pointer type to another of
6239 // the same size. Instead of casting the pointer before the store, cast
6240 // the value to be stored.
6242 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
6243 NewCast = ConstantExpr::getCast(C, SrcPTy);
6245 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
6247 SI.getOperand(0)->getName()+".c"), SI);
6249 return new StoreInst(NewCast, CastOp);
6256 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
6257 Value *Val = SI.getOperand(0);
6258 Value *Ptr = SI.getOperand(1);
6260 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
6261 EraseInstFromFunction(SI);
6266 // Do really simple DSE, to catch cases where there are several consequtive
6267 // stores to the same location, separated by a few arithmetic operations. This
6268 // situation often occurs with bitfield accesses.
6269 BasicBlock::iterator BBI = &SI;
6270 for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
6274 if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
6275 // Prev store isn't volatile, and stores to the same location?
6276 if (!PrevSI->isVolatile() && PrevSI->getOperand(1) == SI.getOperand(1)) {
6279 EraseInstFromFunction(*PrevSI);
6285 // Don't skip over loads or things that can modify memory.
6286 if (BBI->mayWriteToMemory() || isa<LoadInst>(BBI))
6291 if (SI.isVolatile()) return 0; // Don't hack volatile stores.
6293 // store X, null -> turns into 'unreachable' in SimplifyCFG
6294 if (isa<ConstantPointerNull>(Ptr)) {
6295 if (!isa<UndefValue>(Val)) {
6296 SI.setOperand(0, UndefValue::get(Val->getType()));
6297 if (Instruction *U = dyn_cast<Instruction>(Val))
6298 WorkList.push_back(U); // Dropped a use.
6301 return 0; // Do not modify these!
6304 // store undef, Ptr -> noop
6305 if (isa<UndefValue>(Val)) {
6306 EraseInstFromFunction(SI);
6311 // If the pointer destination is a cast, see if we can fold the cast into the
6313 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
6314 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
6316 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
6317 if (CE->getOpcode() == Instruction::Cast)
6318 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
6322 // If this store is the last instruction in the basic block, and if the block
6323 // ends with an unconditional branch, try to move it to the successor block.
6325 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
6326 if (BI->isUnconditional()) {
6327 // Check to see if the successor block has exactly two incoming edges. If
6328 // so, see if the other predecessor contains a store to the same location.
6329 // if so, insert a PHI node (if needed) and move the stores down.
6330 BasicBlock *Dest = BI->getSuccessor(0);
6332 pred_iterator PI = pred_begin(Dest);
6333 BasicBlock *Other = 0;
6334 if (*PI != BI->getParent())
6337 if (PI != pred_end(Dest)) {
6338 if (*PI != BI->getParent())
6343 if (++PI != pred_end(Dest))
6346 if (Other) { // If only one other pred...
6347 BBI = Other->getTerminator();
6348 // Make sure this other block ends in an unconditional branch and that
6349 // there is an instruction before the branch.
6350 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
6351 BBI != Other->begin()) {
6353 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
6355 // If this instruction is a store to the same location.
6356 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
6357 // Okay, we know we can perform this transformation. Insert a PHI
6358 // node now if we need it.
6359 Value *MergedVal = OtherStore->getOperand(0);
6360 if (MergedVal != SI.getOperand(0)) {
6361 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
6362 PN->reserveOperandSpace(2);
6363 PN->addIncoming(SI.getOperand(0), SI.getParent());
6364 PN->addIncoming(OtherStore->getOperand(0), Other);
6365 MergedVal = InsertNewInstBefore(PN, Dest->front());
6368 // Advance to a place where it is safe to insert the new store and
6370 BBI = Dest->begin();
6371 while (isa<PHINode>(BBI)) ++BBI;
6372 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
6373 OtherStore->isVolatile()), *BBI);
6375 // Nuke the old stores.
6376 EraseInstFromFunction(SI);
6377 EraseInstFromFunction(*OtherStore);
6389 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
6390 // Change br (not X), label True, label False to: br X, label False, True
6392 BasicBlock *TrueDest;
6393 BasicBlock *FalseDest;
6394 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
6395 !isa<Constant>(X)) {
6396 // Swap Destinations and condition...
6398 BI.setSuccessor(0, FalseDest);
6399 BI.setSuccessor(1, TrueDest);
6403 // Cannonicalize setne -> seteq
6404 Instruction::BinaryOps Op; Value *Y;
6405 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
6406 TrueDest, FalseDest)))
6407 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
6408 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
6409 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
6410 std::string Name = I->getName(); I->setName("");
6411 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
6412 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
6413 // Swap Destinations and condition...
6414 BI.setCondition(NewSCC);
6415 BI.setSuccessor(0, FalseDest);
6416 BI.setSuccessor(1, TrueDest);
6417 removeFromWorkList(I);
6418 I->getParent()->getInstList().erase(I);
6419 WorkList.push_back(cast<Instruction>(NewSCC));
6426 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
6427 Value *Cond = SI.getCondition();
6428 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
6429 if (I->getOpcode() == Instruction::Add)
6430 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
6431 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
6432 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
6433 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
6435 SI.setOperand(0, I->getOperand(0));
6436 WorkList.push_back(I);
6443 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
6444 if (ConstantAggregateZero *C =
6445 dyn_cast<ConstantAggregateZero>(EI.getOperand(0))) {
6446 // If packed val is constant 0, replace extract with scalar 0
6447 const Type *Ty = cast<PackedType>(C->getType())->getElementType();
6448 EI.replaceAllUsesWith(Constant::getNullValue(Ty));
6449 return ReplaceInstUsesWith(EI, Constant::getNullValue(Ty));
6451 if (ConstantPacked *C = dyn_cast<ConstantPacked>(EI.getOperand(0))) {
6452 // If packed val is constant with uniform operands, replace EI
6453 // with that operand
6454 Constant *op0 = cast<Constant>(C->getOperand(0));
6455 for (unsigned i = 1; i < C->getNumOperands(); ++i)
6456 if (C->getOperand(i) != op0) return 0;
6457 return ReplaceInstUsesWith(EI, op0);
6459 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0)))
6460 if (I->hasOneUse()) {
6461 // Push extractelement into predecessor operation if legal and
6462 // profitable to do so
6463 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
6464 if (!isa<Constant>(BO->getOperand(0)) &&
6465 !isa<Constant>(BO->getOperand(1)))
6467 ExtractElementInst *newEI0 =
6468 new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
6470 ExtractElementInst *newEI1 =
6471 new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
6473 InsertNewInstBefore(newEI0, EI);
6474 InsertNewInstBefore(newEI1, EI);
6475 return BinaryOperator::create(BO->getOpcode(), newEI0, newEI1);
6477 switch(I->getOpcode()) {
6478 case Instruction::Load: {
6479 Value *Ptr = InsertCastBefore(I->getOperand(0),
6480 PointerType::get(EI.getType()), EI);
6481 GetElementPtrInst *GEP =
6482 new GetElementPtrInst(Ptr, EI.getOperand(1),
6483 I->getName() + ".gep");
6484 InsertNewInstBefore(GEP, EI);
6485 return new LoadInst(GEP);
6495 void InstCombiner::removeFromWorkList(Instruction *I) {
6496 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
6501 /// TryToSinkInstruction - Try to move the specified instruction from its
6502 /// current block into the beginning of DestBlock, which can only happen if it's
6503 /// safe to move the instruction past all of the instructions between it and the
6504 /// end of its block.
6505 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
6506 assert(I->hasOneUse() && "Invariants didn't hold!");
6508 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
6509 if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
6511 // Do not sink alloca instructions out of the entry block.
6512 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
6515 // We can only sink load instructions if there is nothing between the load and
6516 // the end of block that could change the value.
6517 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
6518 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
6520 if (Scan->mayWriteToMemory())
6524 BasicBlock::iterator InsertPos = DestBlock->begin();
6525 while (isa<PHINode>(InsertPos)) ++InsertPos;
6527 I->moveBefore(InsertPos);
6532 bool InstCombiner::runOnFunction(Function &F) {
6533 bool Changed = false;
6534 TD = &getAnalysis<TargetData>();
6537 // Populate the worklist with the reachable instructions.
6538 std::set<BasicBlock*> Visited;
6539 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
6540 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
6541 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
6542 WorkList.push_back(I);
6544 // Do a quick scan over the function. If we find any blocks that are
6545 // unreachable, remove any instructions inside of them. This prevents
6546 // the instcombine code from having to deal with some bad special cases.
6547 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
6548 if (!Visited.count(BB)) {
6549 Instruction *Term = BB->getTerminator();
6550 while (Term != BB->begin()) { // Remove instrs bottom-up
6551 BasicBlock::iterator I = Term; --I;
6553 DEBUG(std::cerr << "IC: DCE: " << *I);
6556 if (!I->use_empty())
6557 I->replaceAllUsesWith(UndefValue::get(I->getType()));
6558 I->eraseFromParent();
6563 while (!WorkList.empty()) {
6564 Instruction *I = WorkList.back(); // Get an instruction from the worklist
6565 WorkList.pop_back();
6567 // Check to see if we can DCE or ConstantPropagate the instruction...
6568 // Check to see if we can DIE the instruction...
6569 if (isInstructionTriviallyDead(I)) {
6570 // Add operands to the worklist...
6571 if (I->getNumOperands() < 4)
6572 AddUsesToWorkList(*I);
6575 DEBUG(std::cerr << "IC: DCE: " << *I);
6577 I->eraseFromParent();
6578 removeFromWorkList(I);
6582 // Instruction isn't dead, see if we can constant propagate it...
6583 if (Constant *C = ConstantFoldInstruction(I)) {
6584 Value* Ptr = I->getOperand(0);
6585 if (isa<GetElementPtrInst>(I) &&
6586 cast<Constant>(Ptr)->isNullValue() &&
6587 !isa<ConstantPointerNull>(C) &&
6588 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
6589 // If this is a constant expr gep that is effectively computing an
6590 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
6591 bool isFoldableGEP = true;
6592 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
6593 if (!isa<ConstantInt>(I->getOperand(i)))
6594 isFoldableGEP = false;
6595 if (isFoldableGEP) {
6596 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
6597 std::vector<Value*>(I->op_begin()+1, I->op_end()));
6598 C = ConstantUInt::get(Type::ULongTy, Offset);
6599 C = ConstantExpr::getCast(C, TD->getIntPtrType());
6600 C = ConstantExpr::getCast(C, I->getType());
6604 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
6606 // Add operands to the worklist...
6607 AddUsesToWorkList(*I);
6608 ReplaceInstUsesWith(*I, C);
6611 I->getParent()->getInstList().erase(I);
6612 removeFromWorkList(I);
6616 // See if we can trivially sink this instruction to a successor basic block.
6617 if (I->hasOneUse()) {
6618 BasicBlock *BB = I->getParent();
6619 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
6620 if (UserParent != BB) {
6621 bool UserIsSuccessor = false;
6622 // See if the user is one of our successors.
6623 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
6624 if (*SI == UserParent) {
6625 UserIsSuccessor = true;
6629 // If the user is one of our immediate successors, and if that successor
6630 // only has us as a predecessors (we'd have to split the critical edge
6631 // otherwise), we can keep going.
6632 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
6633 next(pred_begin(UserParent)) == pred_end(UserParent))
6634 // Okay, the CFG is simple enough, try to sink this instruction.
6635 Changed |= TryToSinkInstruction(I, UserParent);
6639 // Now that we have an instruction, try combining it to simplify it...
6640 if (Instruction *Result = visit(*I)) {
6642 // Should we replace the old instruction with a new one?
6644 DEBUG(std::cerr << "IC: Old = " << *I
6645 << " New = " << *Result);
6647 // Everything uses the new instruction now.
6648 I->replaceAllUsesWith(Result);
6650 // Push the new instruction and any users onto the worklist.
6651 WorkList.push_back(Result);
6652 AddUsersToWorkList(*Result);
6654 // Move the name to the new instruction first...
6655 std::string OldName = I->getName(); I->setName("");
6656 Result->setName(OldName);
6658 // Insert the new instruction into the basic block...
6659 BasicBlock *InstParent = I->getParent();
6660 BasicBlock::iterator InsertPos = I;
6662 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
6663 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
6666 InstParent->getInstList().insert(InsertPos, Result);
6668 // Make sure that we reprocess all operands now that we reduced their
6670 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
6671 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
6672 WorkList.push_back(OpI);
6674 // Instructions can end up on the worklist more than once. Make sure
6675 // we do not process an instruction that has been deleted.
6676 removeFromWorkList(I);
6678 // Erase the old instruction.
6679 InstParent->getInstList().erase(I);
6681 DEBUG(std::cerr << "IC: MOD = " << *I);
6683 // If the instruction was modified, it's possible that it is now dead.
6684 // if so, remove it.
6685 if (isInstructionTriviallyDead(I)) {
6686 // Make sure we process all operands now that we are reducing their
6688 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
6689 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
6690 WorkList.push_back(OpI);
6692 // Instructions may end up in the worklist more than once. Erase all
6693 // occurrences of this instruction.
6694 removeFromWorkList(I);
6695 I->eraseFromParent();
6697 WorkList.push_back(Result);
6698 AddUsersToWorkList(*Result);
6708 FunctionPass *llvm::createInstructionCombiningPass() {
6709 return new InstCombiner();