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 if (SimplifyDemandedBits(I->getOperand(0),
893 DemandedMask & SrcTy->getIntegralTypeMask(),
894 KnownZero, KnownOne, Depth+1))
896 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
898 // If the sign bit of the input is known set or clear, then we know the
899 // top bits of the result.
900 uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
902 // If the input sign bit is known zero, or if the NewBits are not demanded
903 // convert this into a zero extension.
904 if ((KnownZero & InSignBit) || (NewBits & ~DemandedMask) == NewBits) {
905 // Convert to unsigned first.
907 NewVal = new CastInst(I->getOperand(0), SrcTy->getUnsignedVersion(),
908 I->getOperand(0)->getName());
909 InsertNewInstBefore(NewVal, *I);
910 // Then cast that to the destination type.
911 NewVal = new CastInst(NewVal, I->getType(), I->getName());
912 InsertNewInstBefore(NewVal, *I);
913 return UpdateValueUsesWith(I, NewVal);
914 } else if (KnownOne & InSignBit) { // Input sign bit known set
916 KnownZero &= ~NewBits;
917 } else { // Input sign bit unknown
918 KnownZero &= ~NewBits;
919 KnownOne &= ~NewBits;
924 case Instruction::Shl:
925 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) {
926 if (SimplifyDemandedBits(I->getOperand(0), DemandedMask >> SA->getValue(),
927 KnownZero, KnownOne, Depth+1))
929 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
930 KnownZero <<= SA->getValue();
931 KnownOne <<= SA->getValue();
932 KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
935 case Instruction::Shr:
936 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) {
937 unsigned ShAmt = SA->getValue();
939 // Compute the new bits that are at the top now.
940 uint64_t HighBits = (1ULL << ShAmt)-1;
941 HighBits <<= I->getType()->getPrimitiveSizeInBits() - ShAmt;
942 uint64_t TypeMask = I->getType()->getIntegralTypeMask();
943 if (I->getType()->isUnsigned()) { // Unsigned shift right.
944 if (SimplifyDemandedBits(I->getOperand(0),
945 (DemandedMask << ShAmt) & TypeMask,
946 KnownZero, KnownOne, Depth+1))
948 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
949 KnownZero &= TypeMask;
950 KnownOne &= TypeMask;
953 KnownZero |= HighBits; // high bits known zero.
954 } else { // Signed shift right.
955 if (SimplifyDemandedBits(I->getOperand(0),
956 (DemandedMask << ShAmt) & TypeMask,
957 KnownZero, KnownOne, Depth+1))
959 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
960 KnownZero &= TypeMask;
961 KnownOne &= TypeMask;
962 KnownZero >>= SA->getValue();
963 KnownOne >>= SA->getValue();
965 // Handle the sign bits.
966 uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1);
967 SignBit >>= SA->getValue(); // Adjust to where it is now in the mask.
969 // If the input sign bit is known to be zero, or if none of the top bits
970 // are demanded, turn this into an unsigned shift right.
971 if ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) {
972 // Convert the input to unsigned.
974 NewVal = new CastInst(I->getOperand(0),
975 I->getType()->getUnsignedVersion(),
976 I->getOperand(0)->getName());
977 InsertNewInstBefore(NewVal, *I);
978 // Perform the unsigned shift right.
979 NewVal = new ShiftInst(Instruction::Shr, NewVal, SA, I->getName());
980 InsertNewInstBefore(NewVal, *I);
981 // Then cast that to the destination type.
982 NewVal = new CastInst(NewVal, I->getType(), I->getName());
983 InsertNewInstBefore(NewVal, *I);
984 return UpdateValueUsesWith(I, NewVal);
985 } else if (KnownOne & SignBit) { // New bits are known one.
986 KnownOne |= HighBits;
993 // If the client is only demanding bits that we know, return the known
995 if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask)
996 return UpdateValueUsesWith(I, GetConstantInType(I->getType(), KnownOne));
1000 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
1001 // true when both operands are equal...
1003 static bool isTrueWhenEqual(Instruction &I) {
1004 return I.getOpcode() == Instruction::SetEQ ||
1005 I.getOpcode() == Instruction::SetGE ||
1006 I.getOpcode() == Instruction::SetLE;
1009 /// AssociativeOpt - Perform an optimization on an associative operator. This
1010 /// function is designed to check a chain of associative operators for a
1011 /// potential to apply a certain optimization. Since the optimization may be
1012 /// applicable if the expression was reassociated, this checks the chain, then
1013 /// reassociates the expression as necessary to expose the optimization
1014 /// opportunity. This makes use of a special Functor, which must define
1015 /// 'shouldApply' and 'apply' methods.
1017 template<typename Functor>
1018 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
1019 unsigned Opcode = Root.getOpcode();
1020 Value *LHS = Root.getOperand(0);
1022 // Quick check, see if the immediate LHS matches...
1023 if (F.shouldApply(LHS))
1024 return F.apply(Root);
1026 // Otherwise, if the LHS is not of the same opcode as the root, return.
1027 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1028 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
1029 // Should we apply this transform to the RHS?
1030 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
1032 // If not to the RHS, check to see if we should apply to the LHS...
1033 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
1034 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
1038 // If the functor wants to apply the optimization to the RHS of LHSI,
1039 // reassociate the expression from ((? op A) op B) to (? op (A op B))
1041 BasicBlock *BB = Root.getParent();
1043 // Now all of the instructions are in the current basic block, go ahead
1044 // and perform the reassociation.
1045 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
1047 // First move the selected RHS to the LHS of the root...
1048 Root.setOperand(0, LHSI->getOperand(1));
1050 // Make what used to be the LHS of the root be the user of the root...
1051 Value *ExtraOperand = TmpLHSI->getOperand(1);
1052 if (&Root == TmpLHSI) {
1053 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
1056 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
1057 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
1058 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
1059 BasicBlock::iterator ARI = &Root; ++ARI;
1060 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
1063 // Now propagate the ExtraOperand down the chain of instructions until we
1065 while (TmpLHSI != LHSI) {
1066 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
1067 // Move the instruction to immediately before the chain we are
1068 // constructing to avoid breaking dominance properties.
1069 NextLHSI->getParent()->getInstList().remove(NextLHSI);
1070 BB->getInstList().insert(ARI, NextLHSI);
1073 Value *NextOp = NextLHSI->getOperand(1);
1074 NextLHSI->setOperand(1, ExtraOperand);
1076 ExtraOperand = NextOp;
1079 // Now that the instructions are reassociated, have the functor perform
1080 // the transformation...
1081 return F.apply(Root);
1084 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
1090 // AddRHS - Implements: X + X --> X << 1
1093 AddRHS(Value *rhs) : RHS(rhs) {}
1094 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1095 Instruction *apply(BinaryOperator &Add) const {
1096 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
1097 ConstantInt::get(Type::UByteTy, 1));
1101 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
1103 struct AddMaskingAnd {
1105 AddMaskingAnd(Constant *c) : C2(c) {}
1106 bool shouldApply(Value *LHS) const {
1108 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
1109 ConstantExpr::getAnd(C1, C2)->isNullValue();
1111 Instruction *apply(BinaryOperator &Add) const {
1112 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
1116 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
1118 if (isa<CastInst>(I)) {
1119 if (Constant *SOC = dyn_cast<Constant>(SO))
1120 return ConstantExpr::getCast(SOC, I.getType());
1122 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
1123 SO->getName() + ".cast"), I);
1126 // Figure out if the constant is the left or the right argument.
1127 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
1128 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
1130 if (Constant *SOC = dyn_cast<Constant>(SO)) {
1132 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
1133 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
1136 Value *Op0 = SO, *Op1 = ConstOperand;
1138 std::swap(Op0, Op1);
1140 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
1141 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
1142 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
1143 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
1145 assert(0 && "Unknown binary instruction type!");
1148 return IC->InsertNewInstBefore(New, I);
1151 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
1152 // constant as the other operand, try to fold the binary operator into the
1153 // select arguments. This also works for Cast instructions, which obviously do
1154 // not have a second operand.
1155 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
1157 // Don't modify shared select instructions
1158 if (!SI->hasOneUse()) return 0;
1159 Value *TV = SI->getOperand(1);
1160 Value *FV = SI->getOperand(2);
1162 if (isa<Constant>(TV) || isa<Constant>(FV)) {
1163 // Bool selects with constant operands can be folded to logical ops.
1164 if (SI->getType() == Type::BoolTy) return 0;
1166 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
1167 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
1169 return new SelectInst(SI->getCondition(), SelectTrueVal,
1176 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
1177 /// node as operand #0, see if we can fold the instruction into the PHI (which
1178 /// is only possible if all operands to the PHI are constants).
1179 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
1180 PHINode *PN = cast<PHINode>(I.getOperand(0));
1181 unsigned NumPHIValues = PN->getNumIncomingValues();
1182 if (!PN->hasOneUse() || NumPHIValues == 0 ||
1183 !isa<Constant>(PN->getIncomingValue(0))) return 0;
1185 // Check to see if all of the operands of the PHI are constants. If not, we
1186 // cannot do the transformation.
1187 for (unsigned i = 1; i != NumPHIValues; ++i)
1188 if (!isa<Constant>(PN->getIncomingValue(i)))
1191 // Okay, we can do the transformation: create the new PHI node.
1192 PHINode *NewPN = new PHINode(I.getType(), I.getName());
1194 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
1195 InsertNewInstBefore(NewPN, *PN);
1197 // Next, add all of the operands to the PHI.
1198 if (I.getNumOperands() == 2) {
1199 Constant *C = cast<Constant>(I.getOperand(1));
1200 for (unsigned i = 0; i != NumPHIValues; ++i) {
1201 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
1202 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
1203 PN->getIncomingBlock(i));
1206 assert(isa<CastInst>(I) && "Unary op should be a cast!");
1207 const Type *RetTy = I.getType();
1208 for (unsigned i = 0; i != NumPHIValues; ++i) {
1209 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
1210 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
1211 PN->getIncomingBlock(i));
1214 return ReplaceInstUsesWith(I, NewPN);
1217 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
1218 bool Changed = SimplifyCommutative(I);
1219 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1221 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1222 // X + undef -> undef
1223 if (isa<UndefValue>(RHS))
1224 return ReplaceInstUsesWith(I, RHS);
1227 if (!I.getType()->isFloatingPoint()) { // NOTE: -0 + +0 = +0.
1228 if (RHSC->isNullValue())
1229 return ReplaceInstUsesWith(I, LHS);
1230 } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1231 if (CFP->isExactlyValue(-0.0))
1232 return ReplaceInstUsesWith(I, LHS);
1235 // X + (signbit) --> X ^ signbit
1236 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
1237 uint64_t Val = CI->getZExtValue();
1238 if (Val == (1ULL << (CI->getType()->getPrimitiveSizeInBits()-1)))
1239 return BinaryOperator::createXor(LHS, RHS);
1242 if (isa<PHINode>(LHS))
1243 if (Instruction *NV = FoldOpIntoPhi(I))
1246 ConstantInt *XorRHS = 0;
1248 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
1249 unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
1250 int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
1251 uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
1253 uint64_t C0080Val = 1ULL << 31;
1254 int64_t CFF80Val = -C0080Val;
1257 if (TySizeBits > Size) {
1259 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
1260 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
1261 if (RHSSExt == CFF80Val) {
1262 if (XorRHS->getZExtValue() == C0080Val)
1264 } else if (RHSZExt == C0080Val) {
1265 if (XorRHS->getSExtValue() == CFF80Val)
1269 // This is a sign extend if the top bits are known zero.
1270 uint64_t Mask = ~0ULL;
1271 Mask <<= 64-(TySizeBits-Size);
1272 Mask &= XorLHS->getType()->getIntegralTypeMask();
1273 if (!MaskedValueIsZero(XorLHS, Mask))
1274 Size = 0; // Not a sign ext, but can't be any others either.
1281 } while (Size >= 8);
1284 const Type *MiddleType = 0;
1287 case 32: MiddleType = Type::IntTy; break;
1288 case 16: MiddleType = Type::ShortTy; break;
1289 case 8: MiddleType = Type::SByteTy; break;
1292 Instruction *NewTrunc = new CastInst(XorLHS, MiddleType, "sext");
1293 InsertNewInstBefore(NewTrunc, I);
1294 return new CastInst(NewTrunc, I.getType());
1300 if (I.getType()->isInteger()) {
1301 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
1303 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
1304 if (RHSI->getOpcode() == Instruction::Sub)
1305 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
1306 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
1308 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
1309 if (LHSI->getOpcode() == Instruction::Sub)
1310 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
1311 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
1316 if (Value *V = dyn_castNegVal(LHS))
1317 return BinaryOperator::createSub(RHS, V);
1320 if (!isa<Constant>(RHS))
1321 if (Value *V = dyn_castNegVal(RHS))
1322 return BinaryOperator::createSub(LHS, V);
1326 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
1327 if (X == RHS) // X*C + X --> X * (C+1)
1328 return BinaryOperator::createMul(RHS, AddOne(C2));
1330 // X*C1 + X*C2 --> X * (C1+C2)
1332 if (X == dyn_castFoldableMul(RHS, C1))
1333 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
1336 // X + X*C --> X * (C+1)
1337 if (dyn_castFoldableMul(RHS, C2) == LHS)
1338 return BinaryOperator::createMul(LHS, AddOne(C2));
1341 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
1342 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
1343 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
1345 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
1347 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
1348 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
1349 return BinaryOperator::createSub(C, X);
1352 // (X & FF00) + xx00 -> (X+xx00) & FF00
1353 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
1354 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
1355 if (Anded == CRHS) {
1356 // See if all bits from the first bit set in the Add RHS up are included
1357 // in the mask. First, get the rightmost bit.
1358 uint64_t AddRHSV = CRHS->getRawValue();
1360 // Form a mask of all bits from the lowest bit added through the top.
1361 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
1362 AddRHSHighBits &= C2->getType()->getIntegralTypeMask();
1364 // See if the and mask includes all of these bits.
1365 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
1367 if (AddRHSHighBits == AddRHSHighBitsAnd) {
1368 // Okay, the xform is safe. Insert the new add pronto.
1369 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
1370 LHS->getName()), I);
1371 return BinaryOperator::createAnd(NewAdd, C2);
1376 // Try to fold constant add into select arguments.
1377 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
1378 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1382 return Changed ? &I : 0;
1385 // isSignBit - Return true if the value represented by the constant only has the
1386 // highest order bit set.
1387 static bool isSignBit(ConstantInt *CI) {
1388 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
1389 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
1392 /// RemoveNoopCast - Strip off nonconverting casts from the value.
1394 static Value *RemoveNoopCast(Value *V) {
1395 if (CastInst *CI = dyn_cast<CastInst>(V)) {
1396 const Type *CTy = CI->getType();
1397 const Type *OpTy = CI->getOperand(0)->getType();
1398 if (CTy->isInteger() && OpTy->isInteger()) {
1399 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
1400 return RemoveNoopCast(CI->getOperand(0));
1401 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
1402 return RemoveNoopCast(CI->getOperand(0));
1407 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
1408 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1410 if (Op0 == Op1) // sub X, X -> 0
1411 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1413 // If this is a 'B = x-(-A)', change to B = x+A...
1414 if (Value *V = dyn_castNegVal(Op1))
1415 return BinaryOperator::createAdd(Op0, V);
1417 if (isa<UndefValue>(Op0))
1418 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
1419 if (isa<UndefValue>(Op1))
1420 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
1422 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
1423 // Replace (-1 - A) with (~A)...
1424 if (C->isAllOnesValue())
1425 return BinaryOperator::createNot(Op1);
1427 // C - ~X == X + (1+C)
1429 if (match(Op1, m_Not(m_Value(X))))
1430 return BinaryOperator::createAdd(X,
1431 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
1432 // -((uint)X >> 31) -> ((int)X >> 31)
1433 // -((int)X >> 31) -> ((uint)X >> 31)
1434 if (C->isNullValue()) {
1435 Value *NoopCastedRHS = RemoveNoopCast(Op1);
1436 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
1437 if (SI->getOpcode() == Instruction::Shr)
1438 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
1440 if (SI->getType()->isSigned())
1441 NewTy = SI->getType()->getUnsignedVersion();
1443 NewTy = SI->getType()->getSignedVersion();
1444 // Check to see if we are shifting out everything but the sign bit.
1445 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
1446 // Ok, the transformation is safe. Insert a cast of the incoming
1447 // value, then the new shift, then the new cast.
1448 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
1449 SI->getOperand(0)->getName());
1450 Value *InV = InsertNewInstBefore(FirstCast, I);
1451 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
1453 if (NewShift->getType() == I.getType())
1456 InV = InsertNewInstBefore(NewShift, I);
1457 return new CastInst(NewShift, I.getType());
1463 // Try to fold constant sub into select arguments.
1464 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1465 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1468 if (isa<PHINode>(Op0))
1469 if (Instruction *NV = FoldOpIntoPhi(I))
1473 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
1474 if (Op1I->getOpcode() == Instruction::Add &&
1475 !Op0->getType()->isFloatingPoint()) {
1476 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
1477 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
1478 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
1479 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
1480 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
1481 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
1482 // C1-(X+C2) --> (C1-C2)-X
1483 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
1484 Op1I->getOperand(0));
1488 if (Op1I->hasOneUse()) {
1489 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
1490 // is not used by anyone else...
1492 if (Op1I->getOpcode() == Instruction::Sub &&
1493 !Op1I->getType()->isFloatingPoint()) {
1494 // Swap the two operands of the subexpr...
1495 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
1496 Op1I->setOperand(0, IIOp1);
1497 Op1I->setOperand(1, IIOp0);
1499 // Create the new top level add instruction...
1500 return BinaryOperator::createAdd(Op0, Op1);
1503 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
1505 if (Op1I->getOpcode() == Instruction::And &&
1506 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
1507 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
1510 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
1511 return BinaryOperator::createAnd(Op0, NewNot);
1514 // -(X sdiv C) -> (X sdiv -C)
1515 if (Op1I->getOpcode() == Instruction::Div)
1516 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
1517 if (CSI->isNullValue())
1518 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
1519 return BinaryOperator::createDiv(Op1I->getOperand(0),
1520 ConstantExpr::getNeg(DivRHS));
1522 // X - X*C --> X * (1-C)
1523 ConstantInt *C2 = 0;
1524 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
1526 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
1527 return BinaryOperator::createMul(Op0, CP1);
1532 if (!Op0->getType()->isFloatingPoint())
1533 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
1534 if (Op0I->getOpcode() == Instruction::Add) {
1535 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
1536 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1537 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
1538 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1539 } else if (Op0I->getOpcode() == Instruction::Sub) {
1540 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
1541 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
1545 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1546 if (X == Op1) { // X*C - X --> X * (C-1)
1547 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
1548 return BinaryOperator::createMul(Op1, CP1);
1551 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1552 if (X == dyn_castFoldableMul(Op1, C2))
1553 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
1558 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
1559 /// really just returns true if the most significant (sign) bit is set.
1560 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
1561 if (RHS->getType()->isSigned()) {
1562 // True if source is LHS < 0 or LHS <= -1
1563 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
1564 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
1566 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
1567 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
1568 // the size of the integer type.
1569 if (Opcode == Instruction::SetGE)
1570 return RHSC->getValue() ==
1571 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
1572 if (Opcode == Instruction::SetGT)
1573 return RHSC->getValue() ==
1574 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
1579 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
1580 bool Changed = SimplifyCommutative(I);
1581 Value *Op0 = I.getOperand(0);
1583 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
1584 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1586 // Simplify mul instructions with a constant RHS...
1587 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
1588 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1590 // ((X << C1)*C2) == (X * (C2 << C1))
1591 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
1592 if (SI->getOpcode() == Instruction::Shl)
1593 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
1594 return BinaryOperator::createMul(SI->getOperand(0),
1595 ConstantExpr::getShl(CI, ShOp));
1597 if (CI->isNullValue())
1598 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
1599 if (CI->equalsInt(1)) // X * 1 == X
1600 return ReplaceInstUsesWith(I, Op0);
1601 if (CI->isAllOnesValue()) // X * -1 == 0 - X
1602 return BinaryOperator::createNeg(Op0, I.getName());
1604 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
1605 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
1606 uint64_t C = Log2_64(Val);
1607 return new ShiftInst(Instruction::Shl, Op0,
1608 ConstantUInt::get(Type::UByteTy, C));
1610 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
1611 if (Op1F->isNullValue())
1612 return ReplaceInstUsesWith(I, Op1);
1614 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
1615 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
1616 if (Op1F->getValue() == 1.0)
1617 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
1620 // Try to fold constant mul into select arguments.
1621 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1622 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1625 if (isa<PHINode>(Op0))
1626 if (Instruction *NV = FoldOpIntoPhi(I))
1630 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
1631 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
1632 return BinaryOperator::createMul(Op0v, Op1v);
1634 // If one of the operands of the multiply is a cast from a boolean value, then
1635 // we know the bool is either zero or one, so this is a 'masking' multiply.
1636 // See if we can simplify things based on how the boolean was originally
1638 CastInst *BoolCast = 0;
1639 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
1640 if (CI->getOperand(0)->getType() == Type::BoolTy)
1643 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
1644 if (CI->getOperand(0)->getType() == Type::BoolTy)
1647 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
1648 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
1649 const Type *SCOpTy = SCIOp0->getType();
1651 // If the setcc is true iff the sign bit of X is set, then convert this
1652 // multiply into a shift/and combination.
1653 if (isa<ConstantInt>(SCIOp1) &&
1654 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
1655 // Shift the X value right to turn it into "all signbits".
1656 Constant *Amt = ConstantUInt::get(Type::UByteTy,
1657 SCOpTy->getPrimitiveSizeInBits()-1);
1658 if (SCIOp0->getType()->isUnsigned()) {
1659 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
1660 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
1661 SCIOp0->getName()), I);
1665 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
1666 BoolCast->getOperand(0)->getName()+
1669 // If the multiply type is not the same as the source type, sign extend
1670 // or truncate to the multiply type.
1671 if (I.getType() != V->getType())
1672 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1674 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1675 return BinaryOperator::createAnd(V, OtherOp);
1680 return Changed ? &I : 0;
1683 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1684 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1686 if (isa<UndefValue>(Op0)) // undef / X -> 0
1687 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1688 if (isa<UndefValue>(Op1))
1689 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1691 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1693 if (RHS->equalsInt(1))
1694 return ReplaceInstUsesWith(I, Op0);
1697 if (RHS->isAllOnesValue())
1698 return BinaryOperator::createNeg(Op0);
1700 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1701 if (LHS->getOpcode() == Instruction::Div)
1702 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1703 // (X / C1) / C2 -> X / (C1*C2)
1704 return BinaryOperator::createDiv(LHS->getOperand(0),
1705 ConstantExpr::getMul(RHS, LHSRHS));
1708 // Check to see if this is an unsigned division with an exact power of 2,
1709 // if so, convert to a right shift.
1710 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1711 if (uint64_t Val = C->getValue()) // Don't break X / 0
1712 if (isPowerOf2_64(Val)) {
1713 uint64_t C = Log2_64(Val);
1714 return new ShiftInst(Instruction::Shr, Op0,
1715 ConstantUInt::get(Type::UByteTy, C));
1719 if (RHS->getType()->isSigned())
1720 if (Value *LHSNeg = dyn_castNegVal(Op0))
1721 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1723 if (!RHS->isNullValue()) {
1724 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1725 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1727 if (isa<PHINode>(Op0))
1728 if (Instruction *NV = FoldOpIntoPhi(I))
1733 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1734 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1735 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1736 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1737 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1738 if (STO->getValue() == 0) { // Couldn't be this argument.
1739 I.setOperand(1, SFO);
1741 } else if (SFO->getValue() == 0) {
1742 I.setOperand(1, STO);
1746 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1747 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1748 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1749 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1750 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1751 TC, SI->getName()+".t");
1752 TSI = InsertNewInstBefore(TSI, I);
1754 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1755 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1756 FC, SI->getName()+".f");
1757 FSI = InsertNewInstBefore(FSI, I);
1758 return new SelectInst(SI->getOperand(0), TSI, FSI);
1762 // 0 / X == 0, we don't need to preserve faults!
1763 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1764 if (LHS->equalsInt(0))
1765 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1767 if (I.getType()->isSigned()) {
1768 // If the sign bits of both operands are zero (i.e. we can prove they are
1769 // unsigned inputs), turn this into a udiv.
1770 uint64_t Mask = 1ULL << (I.getType()->getPrimitiveSizeInBits()-1);
1771 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
1772 const Type *NTy = Op0->getType()->getUnsignedVersion();
1773 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1774 InsertNewInstBefore(LHS, I);
1776 if (Constant *R = dyn_cast<Constant>(Op1))
1777 RHS = ConstantExpr::getCast(R, NTy);
1779 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1780 Instruction *Div = BinaryOperator::createDiv(LHS, RHS, I.getName());
1781 InsertNewInstBefore(Div, I);
1782 return new CastInst(Div, I.getType());
1785 // Known to be an unsigned division.
1786 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
1787 // Turn A / (C1 << N), where C1 is "1<<C2" into A >> (N+C2) [udiv only].
1788 if (RHSI->getOpcode() == Instruction::Shl &&
1789 isa<ConstantUInt>(RHSI->getOperand(0))) {
1790 unsigned C1 = cast<ConstantUInt>(RHSI->getOperand(0))->getRawValue();
1791 if (isPowerOf2_64(C1)) {
1792 unsigned C2 = Log2_64(C1);
1793 Value *Add = RHSI->getOperand(1);
1795 Constant *C2V = ConstantUInt::get(Add->getType(), C2);
1796 Add = InsertNewInstBefore(BinaryOperator::createAdd(Add, C2V,
1799 return new ShiftInst(Instruction::Shr, Op0, Add);
1809 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1810 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1811 if (I.getType()->isSigned()) {
1812 if (Value *RHSNeg = dyn_castNegVal(Op1))
1813 if (!isa<ConstantSInt>(RHSNeg) ||
1814 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1816 AddUsesToWorkList(I);
1817 I.setOperand(1, RHSNeg);
1821 // If the top bits of both operands are zero (i.e. we can prove they are
1822 // unsigned inputs), turn this into a urem.
1823 uint64_t Mask = 1ULL << (I.getType()->getPrimitiveSizeInBits()-1);
1824 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
1825 const Type *NTy = Op0->getType()->getUnsignedVersion();
1826 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1827 InsertNewInstBefore(LHS, I);
1829 if (Constant *R = dyn_cast<Constant>(Op1))
1830 RHS = ConstantExpr::getCast(R, NTy);
1832 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1833 Instruction *Rem = BinaryOperator::createRem(LHS, RHS, I.getName());
1834 InsertNewInstBefore(Rem, I);
1835 return new CastInst(Rem, I.getType());
1839 if (isa<UndefValue>(Op0)) // undef % X -> 0
1840 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1841 if (isa<UndefValue>(Op1))
1842 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1844 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1845 if (RHS->equalsInt(1)) // X % 1 == 0
1846 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1848 // Check to see if this is an unsigned remainder with an exact power of 2,
1849 // if so, convert to a bitwise and.
1850 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1851 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1852 if (!(Val & (Val-1))) // Power of 2
1853 return BinaryOperator::createAnd(Op0,
1854 ConstantUInt::get(I.getType(), Val-1));
1856 if (!RHS->isNullValue()) {
1857 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1858 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1860 if (isa<PHINode>(Op0))
1861 if (Instruction *NV = FoldOpIntoPhi(I))
1866 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1867 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1868 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1869 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1870 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1871 if (STO->getValue() == 0) { // Couldn't be this argument.
1872 I.setOperand(1, SFO);
1874 } else if (SFO->getValue() == 0) {
1875 I.setOperand(1, STO);
1879 if (!(STO->getValue() & (STO->getValue()-1)) &&
1880 !(SFO->getValue() & (SFO->getValue()-1))) {
1881 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1882 SubOne(STO), SI->getName()+".t"), I);
1883 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1884 SubOne(SFO), SI->getName()+".f"), I);
1885 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1889 // 0 % X == 0, we don't need to preserve faults!
1890 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1891 if (LHS->equalsInt(0))
1892 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1895 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
1896 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) [urem only].
1897 if (I.getType()->isUnsigned() &&
1898 RHSI->getOpcode() == Instruction::Shl &&
1899 isa<ConstantUInt>(RHSI->getOperand(0))) {
1900 unsigned C1 = cast<ConstantUInt>(RHSI->getOperand(0))->getRawValue();
1901 if (isPowerOf2_64(C1)) {
1902 Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
1903 Value *Add = InsertNewInstBefore(BinaryOperator::createAdd(RHSI, N1,
1905 return BinaryOperator::createAnd(Op0, Add);
1913 // isMaxValueMinusOne - return true if this is Max-1
1914 static bool isMaxValueMinusOne(const ConstantInt *C) {
1915 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1916 return CU->getValue() == C->getType()->getIntegralTypeMask()-1;
1918 const ConstantSInt *CS = cast<ConstantSInt>(C);
1920 // Calculate 0111111111..11111
1921 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1922 int64_t Val = INT64_MAX; // All ones
1923 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1924 return CS->getValue() == Val-1;
1927 // isMinValuePlusOne - return true if this is Min+1
1928 static bool isMinValuePlusOne(const ConstantInt *C) {
1929 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1930 return CU->getValue() == 1;
1932 const ConstantSInt *CS = cast<ConstantSInt>(C);
1934 // Calculate 1111111111000000000000
1935 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1936 int64_t Val = -1; // All ones
1937 Val <<= TypeBits-1; // Shift over to the right spot
1938 return CS->getValue() == Val+1;
1941 // isOneBitSet - Return true if there is exactly one bit set in the specified
1943 static bool isOneBitSet(const ConstantInt *CI) {
1944 uint64_t V = CI->getRawValue();
1945 return V && (V & (V-1)) == 0;
1948 #if 0 // Currently unused
1949 // isLowOnes - Return true if the constant is of the form 0+1+.
1950 static bool isLowOnes(const ConstantInt *CI) {
1951 uint64_t V = CI->getRawValue();
1953 // There won't be bits set in parts that the type doesn't contain.
1954 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1956 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1957 return U && V && (U & V) == 0;
1961 // isHighOnes - Return true if the constant is of the form 1+0+.
1962 // This is the same as lowones(~X).
1963 static bool isHighOnes(const ConstantInt *CI) {
1964 uint64_t V = ~CI->getRawValue();
1965 if (~V == 0) return false; // 0's does not match "1+"
1967 // There won't be bits set in parts that the type doesn't contain.
1968 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1970 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1971 return U && V && (U & V) == 0;
1975 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1976 /// are carefully arranged to allow folding of expressions such as:
1978 /// (A < B) | (A > B) --> (A != B)
1980 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1981 /// represents that the comparison is true if A == B, and bit value '1' is true
1984 static unsigned getSetCondCode(const SetCondInst *SCI) {
1985 switch (SCI->getOpcode()) {
1987 case Instruction::SetGT: return 1;
1988 case Instruction::SetEQ: return 2;
1989 case Instruction::SetGE: return 3;
1990 case Instruction::SetLT: return 4;
1991 case Instruction::SetNE: return 5;
1992 case Instruction::SetLE: return 6;
1995 assert(0 && "Invalid SetCC opcode!");
2000 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
2001 /// opcode and two operands into either a constant true or false, or a brand new
2002 /// SetCC instruction.
2003 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
2005 case 0: return ConstantBool::False;
2006 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
2007 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
2008 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
2009 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
2010 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
2011 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
2012 case 7: return ConstantBool::True;
2013 default: assert(0 && "Illegal SetCCCode!"); return 0;
2017 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
2018 struct FoldSetCCLogical {
2021 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
2022 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
2023 bool shouldApply(Value *V) const {
2024 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
2025 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
2026 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
2029 Instruction *apply(BinaryOperator &Log) const {
2030 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
2031 if (SCI->getOperand(0) != LHS) {
2032 assert(SCI->getOperand(1) == LHS);
2033 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
2036 unsigned LHSCode = getSetCondCode(SCI);
2037 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
2039 switch (Log.getOpcode()) {
2040 case Instruction::And: Code = LHSCode & RHSCode; break;
2041 case Instruction::Or: Code = LHSCode | RHSCode; break;
2042 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
2043 default: assert(0 && "Illegal logical opcode!"); return 0;
2046 Value *RV = getSetCCValue(Code, LHS, RHS);
2047 if (Instruction *I = dyn_cast<Instruction>(RV))
2049 // Otherwise, it's a constant boolean value...
2050 return IC.ReplaceInstUsesWith(Log, RV);
2054 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
2055 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
2056 // guaranteed to be either a shift instruction or a binary operator.
2057 Instruction *InstCombiner::OptAndOp(Instruction *Op,
2058 ConstantIntegral *OpRHS,
2059 ConstantIntegral *AndRHS,
2060 BinaryOperator &TheAnd) {
2061 Value *X = Op->getOperand(0);
2062 Constant *Together = 0;
2063 if (!isa<ShiftInst>(Op))
2064 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
2066 switch (Op->getOpcode()) {
2067 case Instruction::Xor:
2068 if (Op->hasOneUse()) {
2069 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
2070 std::string OpName = Op->getName(); Op->setName("");
2071 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
2072 InsertNewInstBefore(And, TheAnd);
2073 return BinaryOperator::createXor(And, Together);
2076 case Instruction::Or:
2077 if (Together == AndRHS) // (X | C) & C --> C
2078 return ReplaceInstUsesWith(TheAnd, AndRHS);
2080 if (Op->hasOneUse() && Together != OpRHS) {
2081 // (X | C1) & C2 --> (X | (C1&C2)) & C2
2082 std::string Op0Name = Op->getName(); Op->setName("");
2083 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
2084 InsertNewInstBefore(Or, TheAnd);
2085 return BinaryOperator::createAnd(Or, AndRHS);
2088 case Instruction::Add:
2089 if (Op->hasOneUse()) {
2090 // Adding a one to a single bit bit-field should be turned into an XOR
2091 // of the bit. First thing to check is to see if this AND is with a
2092 // single bit constant.
2093 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
2095 // Clear bits that are not part of the constant.
2096 AndRHSV &= AndRHS->getType()->getIntegralTypeMask();
2098 // If there is only one bit set...
2099 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
2100 // Ok, at this point, we know that we are masking the result of the
2101 // ADD down to exactly one bit. If the constant we are adding has
2102 // no bits set below this bit, then we can eliminate the ADD.
2103 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
2105 // Check to see if any bits below the one bit set in AndRHSV are set.
2106 if ((AddRHS & (AndRHSV-1)) == 0) {
2107 // If not, the only thing that can effect the output of the AND is
2108 // the bit specified by AndRHSV. If that bit is set, the effect of
2109 // the XOR is to toggle the bit. If it is clear, then the ADD has
2111 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
2112 TheAnd.setOperand(0, X);
2115 std::string Name = Op->getName(); Op->setName("");
2116 // Pull the XOR out of the AND.
2117 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
2118 InsertNewInstBefore(NewAnd, TheAnd);
2119 return BinaryOperator::createXor(NewAnd, AndRHS);
2126 case Instruction::Shl: {
2127 // We know that the AND will not produce any of the bits shifted in, so if
2128 // the anded constant includes them, clear them now!
2130 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
2131 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
2132 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
2134 if (CI == ShlMask) { // Masking out bits that the shift already masks
2135 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
2136 } else if (CI != AndRHS) { // Reducing bits set in and.
2137 TheAnd.setOperand(1, CI);
2142 case Instruction::Shr:
2143 // We know that the AND will not produce any of the bits shifted in, so if
2144 // the anded constant includes them, clear them now! This only applies to
2145 // unsigned shifts, because a signed shr may bring in set bits!
2147 if (AndRHS->getType()->isUnsigned()) {
2148 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
2149 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
2150 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
2152 if (CI == ShrMask) { // Masking out bits that the shift already masks.
2153 return ReplaceInstUsesWith(TheAnd, Op);
2154 } else if (CI != AndRHS) {
2155 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
2158 } else { // Signed shr.
2159 // See if this is shifting in some sign extension, then masking it out
2161 if (Op->hasOneUse()) {
2162 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
2163 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
2164 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
2165 if (CI == AndRHS) { // Masking out bits shifted in.
2166 // Make the argument unsigned.
2167 Value *ShVal = Op->getOperand(0);
2168 ShVal = InsertCastBefore(ShVal,
2169 ShVal->getType()->getUnsignedVersion(),
2171 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
2172 OpRHS, Op->getName()),
2174 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
2175 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
2178 return new CastInst(ShVal, Op->getType());
2188 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
2189 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
2190 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
2191 /// insert new instructions.
2192 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
2193 bool Inside, Instruction &IB) {
2194 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
2195 "Lo is not <= Hi in range emission code!");
2197 if (Lo == Hi) // Trivially false.
2198 return new SetCondInst(Instruction::SetNE, V, V);
2199 if (cast<ConstantIntegral>(Lo)->isMinValue())
2200 return new SetCondInst(Instruction::SetLT, V, Hi);
2202 Constant *AddCST = ConstantExpr::getNeg(Lo);
2203 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
2204 InsertNewInstBefore(Add, IB);
2205 // Convert to unsigned for the comparison.
2206 const Type *UnsType = Add->getType()->getUnsignedVersion();
2207 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
2208 AddCST = ConstantExpr::getAdd(AddCST, Hi);
2209 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2210 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2213 if (Lo == Hi) // Trivially true.
2214 return new SetCondInst(Instruction::SetEQ, V, V);
2216 Hi = SubOne(cast<ConstantInt>(Hi));
2217 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
2218 return new SetCondInst(Instruction::SetGT, V, Hi);
2220 // Emit X-Lo > Hi-Lo-1
2221 Constant *AddCST = ConstantExpr::getNeg(Lo);
2222 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
2223 InsertNewInstBefore(Add, IB);
2224 // Convert to unsigned for the comparison.
2225 const Type *UnsType = Add->getType()->getUnsignedVersion();
2226 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
2227 AddCST = ConstantExpr::getAdd(AddCST, Hi);
2228 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2229 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
2232 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
2233 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
2234 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
2235 // not, since all 1s are not contiguous.
2236 static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
2237 uint64_t V = Val->getRawValue();
2238 if (!isShiftedMask_64(V)) return false;
2240 // look for the first zero bit after the run of ones
2241 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
2242 // look for the first non-zero bit
2243 ME = 64-CountLeadingZeros_64(V);
2249 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
2250 /// where isSub determines whether the operator is a sub. If we can fold one of
2251 /// the following xforms:
2253 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
2254 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
2255 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
2257 /// return (A +/- B).
2259 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
2260 ConstantIntegral *Mask, bool isSub,
2262 Instruction *LHSI = dyn_cast<Instruction>(LHS);
2263 if (!LHSI || LHSI->getNumOperands() != 2 ||
2264 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
2266 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
2268 switch (LHSI->getOpcode()) {
2270 case Instruction::And:
2271 if (ConstantExpr::getAnd(N, Mask) == Mask) {
2272 // If the AndRHS is a power of two minus one (0+1+), this is simple.
2273 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
2276 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
2277 // part, we don't need any explicit masks to take them out of A. If that
2278 // is all N is, ignore it.
2280 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
2281 uint64_t Mask = RHS->getType()->getIntegralTypeMask();
2283 if (MaskedValueIsZero(RHS, Mask))
2288 case Instruction::Or:
2289 case Instruction::Xor:
2290 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
2291 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0 &&
2292 ConstantExpr::getAnd(N, Mask)->isNullValue())
2299 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
2301 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
2302 return InsertNewInstBefore(New, I);
2305 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
2306 bool Changed = SimplifyCommutative(I);
2307 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2309 if (isa<UndefValue>(Op1)) // X & undef -> 0
2310 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2314 return ReplaceInstUsesWith(I, Op1);
2316 // See if we can simplify any instructions used by the instruction whose sole
2317 // purpose is to compute bits we don't care about.
2318 uint64_t KnownZero, KnownOne;
2319 if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
2320 KnownZero, KnownOne))
2323 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
2324 uint64_t AndRHSMask = AndRHS->getZExtValue();
2325 uint64_t TypeMask = Op0->getType()->getIntegralTypeMask();
2326 uint64_t NotAndRHS = AndRHSMask^TypeMask;
2328 // Optimize a variety of ((val OP C1) & C2) combinations...
2329 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
2330 Instruction *Op0I = cast<Instruction>(Op0);
2331 Value *Op0LHS = Op0I->getOperand(0);
2332 Value *Op0RHS = Op0I->getOperand(1);
2333 switch (Op0I->getOpcode()) {
2334 case Instruction::Xor:
2335 case Instruction::Or:
2336 // If the mask is only needed on one incoming arm, push it up.
2337 if (Op0I->hasOneUse()) {
2338 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
2339 // Not masking anything out for the LHS, move to RHS.
2340 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
2341 Op0RHS->getName()+".masked");
2342 InsertNewInstBefore(NewRHS, I);
2343 return BinaryOperator::create(
2344 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
2346 if (!isa<Constant>(Op0RHS) &&
2347 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
2348 // Not masking anything out for the RHS, move to LHS.
2349 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
2350 Op0LHS->getName()+".masked");
2351 InsertNewInstBefore(NewLHS, I);
2352 return BinaryOperator::create(
2353 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
2358 case Instruction::Add:
2359 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
2360 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
2361 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
2362 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
2363 return BinaryOperator::createAnd(V, AndRHS);
2364 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
2365 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
2368 case Instruction::Sub:
2369 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
2370 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
2371 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
2372 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
2373 return BinaryOperator::createAnd(V, AndRHS);
2377 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2378 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
2380 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
2381 const Type *SrcTy = CI->getOperand(0)->getType();
2383 // If this is an integer truncation or change from signed-to-unsigned, and
2384 // if the source is an and/or with immediate, transform it. This
2385 // frequently occurs for bitfield accesses.
2386 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
2387 if (SrcTy->getPrimitiveSizeInBits() >=
2388 I.getType()->getPrimitiveSizeInBits() &&
2389 CastOp->getNumOperands() == 2)
2390 if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1)))
2391 if (CastOp->getOpcode() == Instruction::And) {
2392 // Change: and (cast (and X, C1) to T), C2
2393 // into : and (cast X to T), trunc(C1)&C2
2394 // This will folds the two ands together, which may allow other
2396 Instruction *NewCast =
2397 new CastInst(CastOp->getOperand(0), I.getType(),
2398 CastOp->getName()+".shrunk");
2399 NewCast = InsertNewInstBefore(NewCast, I);
2401 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
2402 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
2403 return BinaryOperator::createAnd(NewCast, C3);
2404 } else if (CastOp->getOpcode() == Instruction::Or) {
2405 // Change: and (cast (or X, C1) to T), C2
2406 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
2407 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
2408 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
2409 return ReplaceInstUsesWith(I, AndRHS);
2414 // Try to fold constant and into select arguments.
2415 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2416 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2418 if (isa<PHINode>(Op0))
2419 if (Instruction *NV = FoldOpIntoPhi(I))
2423 Value *Op0NotVal = dyn_castNotVal(Op0);
2424 Value *Op1NotVal = dyn_castNotVal(Op1);
2426 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
2427 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2429 // (~A & ~B) == (~(A | B)) - De Morgan's Law
2430 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2431 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
2432 I.getName()+".demorgan");
2433 InsertNewInstBefore(Or, I);
2434 return BinaryOperator::createNot(Or);
2437 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
2438 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
2439 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2442 Value *LHSVal, *RHSVal;
2443 ConstantInt *LHSCst, *RHSCst;
2444 Instruction::BinaryOps LHSCC, RHSCC;
2445 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2446 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2447 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
2448 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2449 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2450 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2451 // Ensure that the larger constant is on the RHS.
2452 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2453 SetCondInst *LHS = cast<SetCondInst>(Op0);
2454 if (cast<ConstantBool>(Cmp)->getValue()) {
2455 std::swap(LHS, RHS);
2456 std::swap(LHSCst, RHSCst);
2457 std::swap(LHSCC, RHSCC);
2460 // At this point, we know we have have two setcc instructions
2461 // comparing a value against two constants and and'ing the result
2462 // together. Because of the above check, we know that we only have
2463 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2464 // FoldSetCCLogical check above), that the two constants are not
2466 assert(LHSCst != RHSCst && "Compares not folded above?");
2469 default: assert(0 && "Unknown integer condition code!");
2470 case Instruction::SetEQ:
2472 default: assert(0 && "Unknown integer condition code!");
2473 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
2474 case Instruction::SetGT: // (X == 13 & X > 15) -> false
2475 return ReplaceInstUsesWith(I, ConstantBool::False);
2476 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
2477 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
2478 return ReplaceInstUsesWith(I, LHS);
2480 case Instruction::SetNE:
2482 default: assert(0 && "Unknown integer condition code!");
2483 case Instruction::SetLT:
2484 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
2485 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
2486 break; // (X != 13 & X < 15) -> no change
2487 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
2488 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
2489 return ReplaceInstUsesWith(I, RHS);
2490 case Instruction::SetNE:
2491 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
2492 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2493 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2494 LHSVal->getName()+".off");
2495 InsertNewInstBefore(Add, I);
2496 const Type *UnsType = Add->getType()->getUnsignedVersion();
2497 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2498 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
2499 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2500 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
2502 break; // (X != 13 & X != 15) -> no change
2505 case Instruction::SetLT:
2507 default: assert(0 && "Unknown integer condition code!");
2508 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
2509 case Instruction::SetGT: // (X < 13 & X > 15) -> false
2510 return ReplaceInstUsesWith(I, ConstantBool::False);
2511 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
2512 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
2513 return ReplaceInstUsesWith(I, LHS);
2515 case Instruction::SetGT:
2517 default: assert(0 && "Unknown integer condition code!");
2518 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
2519 return ReplaceInstUsesWith(I, LHS);
2520 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
2521 return ReplaceInstUsesWith(I, RHS);
2522 case Instruction::SetNE:
2523 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
2524 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
2525 break; // (X > 13 & X != 15) -> no change
2526 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
2527 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
2533 return Changed ? &I : 0;
2536 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
2537 bool Changed = SimplifyCommutative(I);
2538 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2540 if (isa<UndefValue>(Op1))
2541 return ReplaceInstUsesWith(I, // X | undef -> -1
2542 ConstantIntegral::getAllOnesValue(I.getType()));
2546 return ReplaceInstUsesWith(I, Op0);
2548 // See if we can simplify any instructions used by the instruction whose sole
2549 // purpose is to compute bits we don't care about.
2550 uint64_t KnownZero, KnownOne;
2551 if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
2552 KnownZero, KnownOne))
2556 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2557 ConstantInt *C1 = 0; Value *X = 0;
2558 // (X & C1) | C2 --> (X | C2) & (C1|C2)
2559 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2560 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
2562 InsertNewInstBefore(Or, I);
2563 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
2566 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
2567 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2568 std::string Op0Name = Op0->getName(); Op0->setName("");
2569 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
2570 InsertNewInstBefore(Or, I);
2571 return BinaryOperator::createXor(Or,
2572 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
2575 // Try to fold constant and into select arguments.
2576 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2577 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2579 if (isa<PHINode>(Op0))
2580 if (Instruction *NV = FoldOpIntoPhi(I))
2584 Value *A = 0, *B = 0;
2585 ConstantInt *C1 = 0, *C2 = 0;
2587 if (match(Op0, m_And(m_Value(A), m_Value(B))))
2588 if (A == Op1 || B == Op1) // (A & ?) | A --> A
2589 return ReplaceInstUsesWith(I, Op1);
2590 if (match(Op1, m_And(m_Value(A), m_Value(B))))
2591 if (A == Op0 || B == Op0) // A | (A & ?) --> A
2592 return ReplaceInstUsesWith(I, Op0);
2594 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
2595 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2596 MaskedValueIsZero(Op1, C1->getZExtValue())) {
2597 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
2599 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2602 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
2603 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2604 MaskedValueIsZero(Op0, C1->getZExtValue())) {
2605 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
2607 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2610 // (A & C1)|(B & C2)
2611 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2612 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
2614 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
2615 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
2618 // If we have: ((V + N) & C1) | (V & C2)
2619 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2620 // replace with V+N.
2621 if (C1 == ConstantExpr::getNot(C2)) {
2622 Value *V1 = 0, *V2 = 0;
2623 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2624 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2625 // Add commutes, try both ways.
2626 if (V1 == B && MaskedValueIsZero(V2, C2->getZExtValue()))
2627 return ReplaceInstUsesWith(I, A);
2628 if (V2 == B && MaskedValueIsZero(V1, C2->getZExtValue()))
2629 return ReplaceInstUsesWith(I, A);
2631 // Or commutes, try both ways.
2632 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2633 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2634 // Add commutes, try both ways.
2635 if (V1 == A && MaskedValueIsZero(V2, C1->getZExtValue()))
2636 return ReplaceInstUsesWith(I, B);
2637 if (V2 == A && MaskedValueIsZero(V1, C1->getZExtValue()))
2638 return ReplaceInstUsesWith(I, B);
2643 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2644 if (A == Op1) // ~A | A == -1
2645 return ReplaceInstUsesWith(I,
2646 ConstantIntegral::getAllOnesValue(I.getType()));
2650 // Note, A is still live here!
2651 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2653 return ReplaceInstUsesWith(I,
2654 ConstantIntegral::getAllOnesValue(I.getType()));
2656 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2657 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2658 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2659 I.getName()+".demorgan"), I);
2660 return BinaryOperator::createNot(And);
2664 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2665 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2666 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2669 Value *LHSVal, *RHSVal;
2670 ConstantInt *LHSCst, *RHSCst;
2671 Instruction::BinaryOps LHSCC, RHSCC;
2672 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2673 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2674 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2675 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2676 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2677 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2678 // Ensure that the larger constant is on the RHS.
2679 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2680 SetCondInst *LHS = cast<SetCondInst>(Op0);
2681 if (cast<ConstantBool>(Cmp)->getValue()) {
2682 std::swap(LHS, RHS);
2683 std::swap(LHSCst, RHSCst);
2684 std::swap(LHSCC, RHSCC);
2687 // At this point, we know we have have two setcc instructions
2688 // comparing a value against two constants and or'ing the result
2689 // together. Because of the above check, we know that we only have
2690 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2691 // FoldSetCCLogical check above), that the two constants are not
2693 assert(LHSCst != RHSCst && "Compares not folded above?");
2696 default: assert(0 && "Unknown integer condition code!");
2697 case Instruction::SetEQ:
2699 default: assert(0 && "Unknown integer condition code!");
2700 case Instruction::SetEQ:
2701 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2702 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2703 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2704 LHSVal->getName()+".off");
2705 InsertNewInstBefore(Add, I);
2706 const Type *UnsType = Add->getType()->getUnsignedVersion();
2707 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2708 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2709 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2710 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2712 break; // (X == 13 | X == 15) -> no change
2714 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2716 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2717 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2718 return ReplaceInstUsesWith(I, RHS);
2721 case Instruction::SetNE:
2723 default: assert(0 && "Unknown integer condition code!");
2724 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2725 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2726 return ReplaceInstUsesWith(I, LHS);
2727 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2728 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2729 return ReplaceInstUsesWith(I, ConstantBool::True);
2732 case Instruction::SetLT:
2734 default: assert(0 && "Unknown integer condition code!");
2735 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2737 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2738 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2739 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2740 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2741 return ReplaceInstUsesWith(I, RHS);
2744 case Instruction::SetGT:
2746 default: assert(0 && "Unknown integer condition code!");
2747 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2748 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2749 return ReplaceInstUsesWith(I, LHS);
2750 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2751 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2752 return ReplaceInstUsesWith(I, ConstantBool::True);
2758 return Changed ? &I : 0;
2761 // XorSelf - Implements: X ^ X --> 0
2764 XorSelf(Value *rhs) : RHS(rhs) {}
2765 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2766 Instruction *apply(BinaryOperator &Xor) const {
2772 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2773 bool Changed = SimplifyCommutative(I);
2774 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2776 if (isa<UndefValue>(Op1))
2777 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2779 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2780 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2781 assert(Result == &I && "AssociativeOpt didn't work?");
2782 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2785 // See if we can simplify any instructions used by the instruction whose sole
2786 // purpose is to compute bits we don't care about.
2787 uint64_t KnownZero, KnownOne;
2788 if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
2789 KnownZero, KnownOne))
2792 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2793 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2794 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2795 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2796 if (RHS == ConstantBool::True && SCI->hasOneUse())
2797 return new SetCondInst(SCI->getInverseCondition(),
2798 SCI->getOperand(0), SCI->getOperand(1));
2800 // ~(c-X) == X-c-1 == X+(-c-1)
2801 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2802 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2803 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2804 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2805 ConstantInt::get(I.getType(), 1));
2806 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2809 // ~(~X & Y) --> (X | ~Y)
2810 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2811 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2812 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2814 BinaryOperator::createNot(Op0I->getOperand(1),
2815 Op0I->getOperand(1)->getName()+".not");
2816 InsertNewInstBefore(NotY, I);
2817 return BinaryOperator::createOr(Op0NotVal, NotY);
2821 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2822 if (Op0I->getOpcode() == Instruction::Add) {
2823 // ~(X-c) --> (-c-1)-X
2824 if (RHS->isAllOnesValue()) {
2825 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2826 return BinaryOperator::createSub(
2827 ConstantExpr::getSub(NegOp0CI,
2828 ConstantInt::get(I.getType(), 1)),
2829 Op0I->getOperand(0));
2834 // Try to fold constant and into select arguments.
2835 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2836 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2838 if (isa<PHINode>(Op0))
2839 if (Instruction *NV = FoldOpIntoPhi(I))
2843 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2845 return ReplaceInstUsesWith(I,
2846 ConstantIntegral::getAllOnesValue(I.getType()));
2848 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2850 return ReplaceInstUsesWith(I,
2851 ConstantIntegral::getAllOnesValue(I.getType()));
2853 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2854 if (Op1I->getOpcode() == Instruction::Or) {
2855 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2856 cast<BinaryOperator>(Op1I)->swapOperands();
2858 std::swap(Op0, Op1);
2859 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2861 std::swap(Op0, Op1);
2863 } else if (Op1I->getOpcode() == Instruction::Xor) {
2864 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2865 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2866 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2867 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2870 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2871 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2872 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2873 cast<BinaryOperator>(Op0I)->swapOperands();
2874 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2875 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2876 Op1->getName()+".not"), I);
2877 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2879 } else if (Op0I->getOpcode() == Instruction::Xor) {
2880 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2881 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2882 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2883 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2886 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2887 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2888 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2891 return Changed ? &I : 0;
2894 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2895 /// overflowed for this type.
2896 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2898 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2899 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2902 static bool isPositive(ConstantInt *C) {
2903 return cast<ConstantSInt>(C)->getValue() >= 0;
2906 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2907 /// overflowed for this type.
2908 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2910 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2912 if (In1->getType()->isUnsigned())
2913 return cast<ConstantUInt>(Result)->getValue() <
2914 cast<ConstantUInt>(In1)->getValue();
2915 if (isPositive(In1) != isPositive(In2))
2917 if (isPositive(In1))
2918 return cast<ConstantSInt>(Result)->getValue() <
2919 cast<ConstantSInt>(In1)->getValue();
2920 return cast<ConstantSInt>(Result)->getValue() >
2921 cast<ConstantSInt>(In1)->getValue();
2924 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2925 /// code necessary to compute the offset from the base pointer (without adding
2926 /// in the base pointer). Return the result as a signed integer of intptr size.
2927 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2928 TargetData &TD = IC.getTargetData();
2929 gep_type_iterator GTI = gep_type_begin(GEP);
2930 const Type *UIntPtrTy = TD.getIntPtrType();
2931 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2932 Value *Result = Constant::getNullValue(SIntPtrTy);
2934 // Build a mask for high order bits.
2935 uint64_t PtrSizeMask = ~0ULL >> (64-TD.getPointerSize()*8);
2937 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2938 Value *Op = GEP->getOperand(i);
2939 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2940 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2942 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2943 if (!OpC->isNullValue()) {
2944 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2945 Scale = ConstantExpr::getMul(OpC, Scale);
2946 if (Constant *RC = dyn_cast<Constant>(Result))
2947 Result = ConstantExpr::getAdd(RC, Scale);
2949 // Emit an add instruction.
2950 Result = IC.InsertNewInstBefore(
2951 BinaryOperator::createAdd(Result, Scale,
2952 GEP->getName()+".offs"), I);
2956 // Convert to correct type.
2957 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2958 Op->getName()+".c"), I);
2960 // We'll let instcombine(mul) convert this to a shl if possible.
2961 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2962 GEP->getName()+".idx"), I);
2964 // Emit an add instruction.
2965 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2966 GEP->getName()+".offs"), I);
2972 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2973 /// else. At this point we know that the GEP is on the LHS of the comparison.
2974 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2975 Instruction::BinaryOps Cond,
2977 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2979 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2980 if (isa<PointerType>(CI->getOperand(0)->getType()))
2981 RHS = CI->getOperand(0);
2983 Value *PtrBase = GEPLHS->getOperand(0);
2984 if (PtrBase == RHS) {
2985 // As an optimization, we don't actually have to compute the actual value of
2986 // OFFSET if this is a seteq or setne comparison, just return whether each
2987 // index is zero or not.
2988 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2989 Instruction *InVal = 0;
2990 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2991 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2993 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2994 if (isa<UndefValue>(C)) // undef index -> undef.
2995 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2996 if (C->isNullValue())
2998 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2999 EmitIt = false; // This is indexing into a zero sized array?
3000 } else if (isa<ConstantInt>(C))
3001 return ReplaceInstUsesWith(I, // No comparison is needed here.
3002 ConstantBool::get(Cond == Instruction::SetNE));
3007 new SetCondInst(Cond, GEPLHS->getOperand(i),
3008 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
3012 InVal = InsertNewInstBefore(InVal, I);
3013 InsertNewInstBefore(Comp, I);
3014 if (Cond == Instruction::SetNE) // True if any are unequal
3015 InVal = BinaryOperator::createOr(InVal, Comp);
3016 else // True if all are equal
3017 InVal = BinaryOperator::createAnd(InVal, Comp);
3025 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
3026 ConstantBool::get(Cond == Instruction::SetEQ));
3029 // Only lower this if the setcc is the only user of the GEP or if we expect
3030 // the result to fold to a constant!
3031 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
3032 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
3033 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
3034 return new SetCondInst(Cond, Offset,
3035 Constant::getNullValue(Offset->getType()));
3037 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
3038 // If the base pointers are different, but the indices are the same, just
3039 // compare the base pointer.
3040 if (PtrBase != GEPRHS->getOperand(0)) {
3041 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
3042 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
3043 GEPRHS->getOperand(0)->getType();
3045 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
3046 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
3047 IndicesTheSame = false;
3051 // If all indices are the same, just compare the base pointers.
3053 return new SetCondInst(Cond, GEPLHS->getOperand(0),
3054 GEPRHS->getOperand(0));
3056 // Otherwise, the base pointers are different and the indices are
3057 // different, bail out.
3061 // If one of the GEPs has all zero indices, recurse.
3062 bool AllZeros = true;
3063 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
3064 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
3065 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
3070 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
3071 SetCondInst::getSwappedCondition(Cond), I);
3073 // If the other GEP has all zero indices, recurse.
3075 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
3076 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
3077 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
3082 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
3084 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
3085 // If the GEPs only differ by one index, compare it.
3086 unsigned NumDifferences = 0; // Keep track of # differences.
3087 unsigned DiffOperand = 0; // The operand that differs.
3088 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
3089 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
3090 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
3091 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
3092 // Irreconcilable differences.
3096 if (NumDifferences++) break;
3101 if (NumDifferences == 0) // SAME GEP?
3102 return ReplaceInstUsesWith(I, // No comparison is needed here.
3103 ConstantBool::get(Cond == Instruction::SetEQ));
3104 else if (NumDifferences == 1) {
3105 Value *LHSV = GEPLHS->getOperand(DiffOperand);
3106 Value *RHSV = GEPRHS->getOperand(DiffOperand);
3108 // Convert the operands to signed values to make sure to perform a
3109 // signed comparison.
3110 const Type *NewTy = LHSV->getType()->getSignedVersion();
3111 if (LHSV->getType() != NewTy)
3112 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
3113 LHSV->getName()), I);
3114 if (RHSV->getType() != NewTy)
3115 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
3116 RHSV->getName()), I);
3117 return new SetCondInst(Cond, LHSV, RHSV);
3121 // Only lower this if the setcc is the only user of the GEP or if we expect
3122 // the result to fold to a constant!
3123 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
3124 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
3125 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
3126 Value *L = EmitGEPOffset(GEPLHS, I, *this);
3127 Value *R = EmitGEPOffset(GEPRHS, I, *this);
3128 return new SetCondInst(Cond, L, R);
3135 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
3136 bool Changed = SimplifyCommutative(I);
3137 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3138 const Type *Ty = Op0->getType();
3142 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
3144 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
3145 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
3147 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
3148 // addresses never equal each other! We already know that Op0 != Op1.
3149 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
3150 isa<ConstantPointerNull>(Op0)) &&
3151 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
3152 isa<ConstantPointerNull>(Op1)))
3153 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
3155 // setcc's with boolean values can always be turned into bitwise operations
3156 if (Ty == Type::BoolTy) {
3157 switch (I.getOpcode()) {
3158 default: assert(0 && "Invalid setcc instruction!");
3159 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
3160 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
3161 InsertNewInstBefore(Xor, I);
3162 return BinaryOperator::createNot(Xor);
3164 case Instruction::SetNE:
3165 return BinaryOperator::createXor(Op0, Op1);
3167 case Instruction::SetGT:
3168 std::swap(Op0, Op1); // Change setgt -> setlt
3170 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
3171 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
3172 InsertNewInstBefore(Not, I);
3173 return BinaryOperator::createAnd(Not, Op1);
3175 case Instruction::SetGE:
3176 std::swap(Op0, Op1); // Change setge -> setle
3178 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
3179 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
3180 InsertNewInstBefore(Not, I);
3181 return BinaryOperator::createOr(Not, Op1);
3186 // See if we are doing a comparison between a constant and an instruction that
3187 // can be folded into the comparison.
3188 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
3189 // Check to see if we are comparing against the minimum or maximum value...
3190 if (CI->isMinValue()) {
3191 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
3192 return ReplaceInstUsesWith(I, ConstantBool::False);
3193 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
3194 return ReplaceInstUsesWith(I, ConstantBool::True);
3195 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
3196 return BinaryOperator::createSetEQ(Op0, Op1);
3197 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
3198 return BinaryOperator::createSetNE(Op0, Op1);
3200 } else if (CI->isMaxValue()) {
3201 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
3202 return ReplaceInstUsesWith(I, ConstantBool::False);
3203 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
3204 return ReplaceInstUsesWith(I, ConstantBool::True);
3205 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
3206 return BinaryOperator::createSetEQ(Op0, Op1);
3207 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
3208 return BinaryOperator::createSetNE(Op0, Op1);
3210 // Comparing against a value really close to min or max?
3211 } else if (isMinValuePlusOne(CI)) {
3212 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
3213 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
3214 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
3215 return BinaryOperator::createSetNE(Op0, SubOne(CI));
3217 } else if (isMaxValueMinusOne(CI)) {
3218 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
3219 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
3220 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
3221 return BinaryOperator::createSetNE(Op0, AddOne(CI));
3224 // If we still have a setle or setge instruction, turn it into the
3225 // appropriate setlt or setgt instruction. Since the border cases have
3226 // already been handled above, this requires little checking.
3228 if (I.getOpcode() == Instruction::SetLE)
3229 return BinaryOperator::createSetLT(Op0, AddOne(CI));
3230 if (I.getOpcode() == Instruction::SetGE)
3231 return BinaryOperator::createSetGT(Op0, SubOne(CI));
3234 // See if we can fold the comparison based on bits known to be zero or one
3236 uint64_t KnownZero, KnownOne;
3237 if (SimplifyDemandedBits(Op0, Ty->getIntegralTypeMask(),
3238 KnownZero, KnownOne, 0))
3241 // Given the known and unknown bits, compute a range that the LHS could be
3243 if (KnownOne | KnownZero) {
3244 if (Ty->isUnsigned()) { // Unsigned comparison.
3246 uint64_t RHSVal = CI->getZExtValue();
3247 ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne,
3249 switch (I.getOpcode()) { // LE/GE have been folded already.
3250 default: assert(0 && "Unknown setcc opcode!");
3251 case Instruction::SetEQ:
3252 if (Max < RHSVal || Min > RHSVal)
3253 return ReplaceInstUsesWith(I, ConstantBool::False);
3255 case Instruction::SetNE:
3256 if (Max < RHSVal || Min > RHSVal)
3257 return ReplaceInstUsesWith(I, ConstantBool::True);
3259 case Instruction::SetLT:
3260 if (Max < RHSVal) return ReplaceInstUsesWith(I, ConstantBool::True);
3261 if (Min > RHSVal) return ReplaceInstUsesWith(I, ConstantBool::False);
3263 case Instruction::SetGT:
3264 if (Min > RHSVal) return ReplaceInstUsesWith(I, ConstantBool::True);
3265 if (Max < RHSVal) return ReplaceInstUsesWith(I, ConstantBool::False);
3268 } else { // Signed comparison.
3270 int64_t RHSVal = CI->getSExtValue();
3271 ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne,
3273 switch (I.getOpcode()) { // LE/GE have been folded already.
3274 default: assert(0 && "Unknown setcc opcode!");
3275 case Instruction::SetEQ:
3276 if (Max < RHSVal || Min > RHSVal)
3277 return ReplaceInstUsesWith(I, ConstantBool::False);
3279 case Instruction::SetNE:
3280 if (Max < RHSVal || Min > RHSVal)
3281 return ReplaceInstUsesWith(I, ConstantBool::True);
3283 case Instruction::SetLT:
3284 if (Max < RHSVal) return ReplaceInstUsesWith(I, ConstantBool::True);
3285 if (Min > RHSVal) return ReplaceInstUsesWith(I, ConstantBool::False);
3287 case Instruction::SetGT:
3288 if (Min > RHSVal) return ReplaceInstUsesWith(I, ConstantBool::True);
3289 if (Max < RHSVal) return ReplaceInstUsesWith(I, ConstantBool::False);
3296 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3297 switch (LHSI->getOpcode()) {
3298 case Instruction::And:
3299 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
3300 LHSI->getOperand(0)->hasOneUse()) {
3301 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
3302 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
3303 // happens a LOT in code produced by the C front-end, for bitfield
3305 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
3306 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
3308 // Check to see if there is a noop-cast between the shift and the and.
3310 if (CastInst *CI = dyn_cast<CastInst>(LHSI->getOperand(0)))
3311 if (CI->getOperand(0)->getType()->isIntegral() &&
3312 CI->getOperand(0)->getType()->getPrimitiveSizeInBits() ==
3313 CI->getType()->getPrimitiveSizeInBits())
3314 Shift = dyn_cast<ShiftInst>(CI->getOperand(0));
3317 ConstantUInt *ShAmt;
3318 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
3319 const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
3320 const Type *AndTy = AndCST->getType(); // Type of the and.
3322 // We can fold this as long as we can't shift unknown bits
3323 // into the mask. This can only happen with signed shift
3324 // rights, as they sign-extend.
3326 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
3329 // To test for the bad case of the signed shr, see if any
3330 // of the bits shifted in could be tested after the mask.
3331 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
3332 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
3334 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
3336 ConstantExpr::getShl(ConstantInt::getAllOnesValue(AndTy),
3338 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
3344 if (Shift->getOpcode() == Instruction::Shl)
3345 NewCst = ConstantExpr::getUShr(CI, ShAmt);
3347 NewCst = ConstantExpr::getShl(CI, ShAmt);
3349 // Check to see if we are shifting out any of the bits being
3351 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
3352 // If we shifted bits out, the fold is not going to work out.
3353 // As a special case, check to see if this means that the
3354 // result is always true or false now.
3355 if (I.getOpcode() == Instruction::SetEQ)
3356 return ReplaceInstUsesWith(I, ConstantBool::False);
3357 if (I.getOpcode() == Instruction::SetNE)
3358 return ReplaceInstUsesWith(I, ConstantBool::True);
3360 I.setOperand(1, NewCst);
3361 Constant *NewAndCST;
3362 if (Shift->getOpcode() == Instruction::Shl)
3363 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
3365 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
3366 LHSI->setOperand(1, NewAndCST);
3368 LHSI->setOperand(0, Shift->getOperand(0));
3370 Value *NewCast = InsertCastBefore(Shift->getOperand(0), AndTy,
3372 LHSI->setOperand(0, NewCast);
3374 WorkList.push_back(Shift); // Shift is dead.
3375 AddUsesToWorkList(I);
3383 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
3384 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
3385 switch (I.getOpcode()) {
3387 case Instruction::SetEQ:
3388 case Instruction::SetNE: {
3389 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
3391 // Check that the shift amount is in range. If not, don't perform
3392 // undefined shifts. When the shift is visited it will be
3394 if (ShAmt->getValue() >= TypeBits)
3397 // If we are comparing against bits always shifted out, the
3398 // comparison cannot succeed.
3400 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
3401 if (Comp != CI) {// Comparing against a bit that we know is zero.
3402 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
3403 Constant *Cst = ConstantBool::get(IsSetNE);
3404 return ReplaceInstUsesWith(I, Cst);
3407 if (LHSI->hasOneUse()) {
3408 // Otherwise strength reduce the shift into an and.
3409 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
3410 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
3413 if (CI->getType()->isUnsigned()) {
3414 Mask = ConstantUInt::get(CI->getType(), Val);
3415 } else if (ShAmtVal != 0) {
3416 Mask = ConstantSInt::get(CI->getType(), Val);
3418 Mask = ConstantInt::getAllOnesValue(CI->getType());
3422 BinaryOperator::createAnd(LHSI->getOperand(0),
3423 Mask, LHSI->getName()+".mask");
3424 Value *And = InsertNewInstBefore(AndI, I);
3425 return new SetCondInst(I.getOpcode(), And,
3426 ConstantExpr::getUShr(CI, ShAmt));
3433 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
3434 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
3435 switch (I.getOpcode()) {
3437 case Instruction::SetEQ:
3438 case Instruction::SetNE: {
3440 // Check that the shift amount is in range. If not, don't perform
3441 // undefined shifts. When the shift is visited it will be
3443 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
3444 if (ShAmt->getValue() >= TypeBits)
3447 // If we are comparing against bits always shifted out, the
3448 // comparison cannot succeed.
3450 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
3452 if (Comp != CI) {// Comparing against a bit that we know is zero.
3453 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
3454 Constant *Cst = ConstantBool::get(IsSetNE);
3455 return ReplaceInstUsesWith(I, Cst);
3458 if (LHSI->hasOneUse() || CI->isNullValue()) {
3459 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
3461 // Otherwise strength reduce the shift into an and.
3462 uint64_t Val = ~0ULL; // All ones.
3463 Val <<= ShAmtVal; // Shift over to the right spot.
3466 if (CI->getType()->isUnsigned()) {
3467 Val &= ~0ULL >> (64-TypeBits);
3468 Mask = ConstantUInt::get(CI->getType(), Val);
3470 Mask = ConstantSInt::get(CI->getType(), Val);
3474 BinaryOperator::createAnd(LHSI->getOperand(0),
3475 Mask, LHSI->getName()+".mask");
3476 Value *And = InsertNewInstBefore(AndI, I);
3477 return new SetCondInst(I.getOpcode(), And,
3478 ConstantExpr::getShl(CI, ShAmt));
3486 case Instruction::Div:
3487 // Fold: (div X, C1) op C2 -> range check
3488 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
3489 // Fold this div into the comparison, producing a range check.
3490 // Determine, based on the divide type, what the range is being
3491 // checked. If there is an overflow on the low or high side, remember
3492 // it, otherwise compute the range [low, hi) bounding the new value.
3493 bool LoOverflow = false, HiOverflow = 0;
3494 ConstantInt *LoBound = 0, *HiBound = 0;
3497 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
3499 Instruction::BinaryOps Opcode = I.getOpcode();
3501 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
3502 } else if (LHSI->getType()->isUnsigned()) { // udiv
3504 LoOverflow = ProdOV;
3505 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
3506 } else if (isPositive(DivRHS)) { // Divisor is > 0.
3507 if (CI->isNullValue()) { // (X / pos) op 0
3509 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
3511 } else if (isPositive(CI)) { // (X / pos) op pos
3513 LoOverflow = ProdOV;
3514 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
3515 } else { // (X / pos) op neg
3516 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
3517 LoOverflow = AddWithOverflow(LoBound, Prod,
3518 cast<ConstantInt>(DivRHSH));
3520 HiOverflow = ProdOV;
3522 } else { // Divisor is < 0.
3523 if (CI->isNullValue()) { // (X / neg) op 0
3524 LoBound = AddOne(DivRHS);
3525 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
3526 if (HiBound == DivRHS)
3527 LoBound = 0; // - INTMIN = INTMIN
3528 } else if (isPositive(CI)) { // (X / neg) op pos
3529 HiOverflow = LoOverflow = ProdOV;
3531 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
3532 HiBound = AddOne(Prod);
3533 } else { // (X / neg) op neg
3535 LoOverflow = HiOverflow = ProdOV;
3536 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
3539 // Dividing by a negate swaps the condition.
3540 Opcode = SetCondInst::getSwappedCondition(Opcode);
3544 Value *X = LHSI->getOperand(0);
3546 default: assert(0 && "Unhandled setcc opcode!");
3547 case Instruction::SetEQ:
3548 if (LoOverflow && HiOverflow)
3549 return ReplaceInstUsesWith(I, ConstantBool::False);
3550 else if (HiOverflow)
3551 return new SetCondInst(Instruction::SetGE, X, LoBound);
3552 else if (LoOverflow)
3553 return new SetCondInst(Instruction::SetLT, X, HiBound);
3555 return InsertRangeTest(X, LoBound, HiBound, true, I);
3556 case Instruction::SetNE:
3557 if (LoOverflow && HiOverflow)
3558 return ReplaceInstUsesWith(I, ConstantBool::True);
3559 else if (HiOverflow)
3560 return new SetCondInst(Instruction::SetLT, X, LoBound);
3561 else if (LoOverflow)
3562 return new SetCondInst(Instruction::SetGE, X, HiBound);
3564 return InsertRangeTest(X, LoBound, HiBound, false, I);
3565 case Instruction::SetLT:
3567 return ReplaceInstUsesWith(I, ConstantBool::False);
3568 return new SetCondInst(Instruction::SetLT, X, LoBound);
3569 case Instruction::SetGT:
3571 return ReplaceInstUsesWith(I, ConstantBool::False);
3572 return new SetCondInst(Instruction::SetGE, X, HiBound);
3579 // Simplify seteq and setne instructions...
3580 if (I.getOpcode() == Instruction::SetEQ ||
3581 I.getOpcode() == Instruction::SetNE) {
3582 bool isSetNE = I.getOpcode() == Instruction::SetNE;
3584 // If the first operand is (and|or|xor) with a constant, and the second
3585 // operand is a constant, simplify a bit.
3586 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
3587 switch (BO->getOpcode()) {
3588 case Instruction::Rem:
3589 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
3590 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
3592 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
3593 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
3594 if (isPowerOf2_64(V)) {
3595 unsigned L2 = Log2_64(V);
3596 const Type *UTy = BO->getType()->getUnsignedVersion();
3597 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
3599 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
3600 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
3601 RHSCst, BO->getName()), I);
3602 return BinaryOperator::create(I.getOpcode(), NewRem,
3603 Constant::getNullValue(UTy));
3608 case Instruction::Add:
3609 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
3610 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3611 if (BO->hasOneUse())
3612 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3613 ConstantExpr::getSub(CI, BOp1C));
3614 } else if (CI->isNullValue()) {
3615 // Replace ((add A, B) != 0) with (A != -B) if A or B is
3616 // efficiently invertible, or if the add has just this one use.
3617 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
3619 if (Value *NegVal = dyn_castNegVal(BOp1))
3620 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
3621 else if (Value *NegVal = dyn_castNegVal(BOp0))
3622 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
3623 else if (BO->hasOneUse()) {
3624 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
3626 InsertNewInstBefore(Neg, I);
3627 return new SetCondInst(I.getOpcode(), BOp0, Neg);
3631 case Instruction::Xor:
3632 // For the xor case, we can xor two constants together, eliminating
3633 // the explicit xor.
3634 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
3635 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
3636 ConstantExpr::getXor(CI, BOC));
3639 case Instruction::Sub:
3640 // Replace (([sub|xor] A, B) != 0) with (A != B)
3641 if (CI->isNullValue())
3642 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3646 case Instruction::Or:
3647 // If bits are being or'd in that are not present in the constant we
3648 // are comparing against, then the comparison could never succeed!
3649 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
3650 Constant *NotCI = ConstantExpr::getNot(CI);
3651 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
3652 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3656 case Instruction::And:
3657 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3658 // If bits are being compared against that are and'd out, then the
3659 // comparison can never succeed!
3660 if (!ConstantExpr::getAnd(CI,
3661 ConstantExpr::getNot(BOC))->isNullValue())
3662 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3664 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3665 if (CI == BOC && isOneBitSet(CI))
3666 return new SetCondInst(isSetNE ? Instruction::SetEQ :
3667 Instruction::SetNE, Op0,
3668 Constant::getNullValue(CI->getType()));
3670 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
3671 // to be a signed value as appropriate.
3672 if (isSignBit(BOC)) {
3673 Value *X = BO->getOperand(0);
3674 // If 'X' is not signed, insert a cast now...
3675 if (!BOC->getType()->isSigned()) {
3676 const Type *DestTy = BOC->getType()->getSignedVersion();
3677 X = InsertCastBefore(X, DestTy, I);
3679 return new SetCondInst(isSetNE ? Instruction::SetLT :
3680 Instruction::SetGE, X,
3681 Constant::getNullValue(X->getType()));
3684 // ((X & ~7) == 0) --> X < 8
3685 if (CI->isNullValue() && isHighOnes(BOC)) {
3686 Value *X = BO->getOperand(0);
3687 Constant *NegX = ConstantExpr::getNeg(BOC);
3689 // If 'X' is signed, insert a cast now.
3690 if (NegX->getType()->isSigned()) {
3691 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3692 X = InsertCastBefore(X, DestTy, I);
3693 NegX = ConstantExpr::getCast(NegX, DestTy);
3696 return new SetCondInst(isSetNE ? Instruction::SetGE :
3697 Instruction::SetLT, X, NegX);
3704 } else { // Not a SetEQ/SetNE
3705 // If the LHS is a cast from an integral value of the same size,
3706 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3707 Value *CastOp = Cast->getOperand(0);
3708 const Type *SrcTy = CastOp->getType();
3709 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3710 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3711 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3712 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3713 "Source and destination signednesses should differ!");
3714 if (Cast->getType()->isSigned()) {
3715 // If this is a signed comparison, check for comparisons in the
3716 // vicinity of zero.
3717 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3719 return BinaryOperator::createSetGT(CastOp,
3720 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3721 else if (I.getOpcode() == Instruction::SetGT &&
3722 cast<ConstantSInt>(CI)->getValue() == -1)
3723 // X > -1 => x < 128
3724 return BinaryOperator::createSetLT(CastOp,
3725 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3727 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3728 if (I.getOpcode() == Instruction::SetLT &&
3729 CUI->getValue() == 1ULL << (SrcTySize-1))
3730 // X < 128 => X > -1
3731 return BinaryOperator::createSetGT(CastOp,
3732 ConstantSInt::get(SrcTy, -1));
3733 else if (I.getOpcode() == Instruction::SetGT &&
3734 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3736 return BinaryOperator::createSetLT(CastOp,
3737 Constant::getNullValue(SrcTy));
3744 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3745 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3746 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3747 switch (LHSI->getOpcode()) {
3748 case Instruction::GetElementPtr:
3749 if (RHSC->isNullValue()) {
3750 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3751 bool isAllZeros = true;
3752 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3753 if (!isa<Constant>(LHSI->getOperand(i)) ||
3754 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3759 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3760 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3764 case Instruction::PHI:
3765 if (Instruction *NV = FoldOpIntoPhi(I))
3768 case Instruction::Select:
3769 // If either operand of the select is a constant, we can fold the
3770 // comparison into the select arms, which will cause one to be
3771 // constant folded and the select turned into a bitwise or.
3772 Value *Op1 = 0, *Op2 = 0;
3773 if (LHSI->hasOneUse()) {
3774 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3775 // Fold the known value into the constant operand.
3776 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3777 // Insert a new SetCC of the other select operand.
3778 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3779 LHSI->getOperand(2), RHSC,
3781 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3782 // Fold the known value into the constant operand.
3783 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3784 // Insert a new SetCC of the other select operand.
3785 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3786 LHSI->getOperand(1), RHSC,
3792 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3797 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3798 if (User *GEP = dyn_castGetElementPtr(Op0))
3799 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3801 if (User *GEP = dyn_castGetElementPtr(Op1))
3802 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3803 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3806 // Test to see if the operands of the setcc are casted versions of other
3807 // values. If the cast can be stripped off both arguments, we do so now.
3808 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3809 Value *CastOp0 = CI->getOperand(0);
3810 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3811 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3812 (I.getOpcode() == Instruction::SetEQ ||
3813 I.getOpcode() == Instruction::SetNE)) {
3814 // We keep moving the cast from the left operand over to the right
3815 // operand, where it can often be eliminated completely.
3818 // If operand #1 is a cast instruction, see if we can eliminate it as
3820 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3821 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3823 Op1 = CI2->getOperand(0);
3825 // If Op1 is a constant, we can fold the cast into the constant.
3826 if (Op1->getType() != Op0->getType())
3827 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3828 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3830 // Otherwise, cast the RHS right before the setcc
3831 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3832 InsertNewInstBefore(cast<Instruction>(Op1), I);
3834 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3837 // Handle the special case of: setcc (cast bool to X), <cst>
3838 // This comes up when you have code like
3841 // For generality, we handle any zero-extension of any operand comparison
3842 // with a constant or another cast from the same type.
3843 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3844 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3847 return Changed ? &I : 0;
3850 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3851 // We only handle extending casts so far.
3853 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3854 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3855 const Type *SrcTy = LHSCIOp->getType();
3856 const Type *DestTy = SCI.getOperand(0)->getType();
3859 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3862 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3863 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3864 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3866 // Is this a sign or zero extension?
3867 bool isSignSrc = SrcTy->isSigned();
3868 bool isSignDest = DestTy->isSigned();
3870 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3871 // Not an extension from the same type?
3872 RHSCIOp = CI->getOperand(0);
3873 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3874 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3875 // Compute the constant that would happen if we truncated to SrcTy then
3876 // reextended to DestTy.
3877 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3879 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3882 // If the value cannot be represented in the shorter type, we cannot emit
3883 // a simple comparison.
3884 if (SCI.getOpcode() == Instruction::SetEQ)
3885 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3886 if (SCI.getOpcode() == Instruction::SetNE)
3887 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3889 // Evaluate the comparison for LT.
3891 if (DestTy->isSigned()) {
3892 // We're performing a signed comparison.
3894 // Signed extend and signed comparison.
3895 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3896 Result = ConstantBool::False;
3898 Result = ConstantBool::True; // X < (large) --> true
3900 // Unsigned extend and signed comparison.
3901 if (cast<ConstantSInt>(CI)->getValue() < 0)
3902 Result = ConstantBool::False;
3904 Result = ConstantBool::True;
3907 // We're performing an unsigned comparison.
3909 // Unsigned extend & compare -> always true.
3910 Result = ConstantBool::True;
3912 // We're performing an unsigned comp with a sign extended value.
3913 // This is true if the input is >= 0. [aka >s -1]
3914 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3915 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3916 NegOne, SCI.getName()), SCI);
3920 // Finally, return the value computed.
3921 if (SCI.getOpcode() == Instruction::SetLT) {
3922 return ReplaceInstUsesWith(SCI, Result);
3924 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3925 if (Constant *CI = dyn_cast<Constant>(Result))
3926 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3928 return BinaryOperator::createNot(Result);
3935 // Okay, just insert a compare of the reduced operands now!
3936 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3939 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3940 assert(I.getOperand(1)->getType() == Type::UByteTy);
3941 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3942 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3944 // shl X, 0 == X and shr X, 0 == X
3945 // shl 0, X == 0 and shr 0, X == 0
3946 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3947 Op0 == Constant::getNullValue(Op0->getType()))
3948 return ReplaceInstUsesWith(I, Op0);
3950 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3951 if (!isLeftShift && I.getType()->isSigned())
3952 return ReplaceInstUsesWith(I, Op0);
3953 else // undef << X -> 0 AND undef >>u X -> 0
3954 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3956 if (isa<UndefValue>(Op1)) {
3957 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3958 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3960 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3963 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3965 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3966 if (CSI->isAllOnesValue())
3967 return ReplaceInstUsesWith(I, CSI);
3969 // Try to fold constant and into select arguments.
3970 if (isa<Constant>(Op0))
3971 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3972 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3975 // See if we can turn a signed shr into an unsigned shr.
3976 if (!isLeftShift && I.getType()->isSigned()) {
3977 if (MaskedValueIsZero(Op0,
3978 1ULL << (I.getType()->getPrimitiveSizeInBits()-1))) {
3979 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3980 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3982 return new CastInst(V, I.getType());
3986 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1))
3987 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
3992 Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
3994 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3995 bool isSignedShift = Op0->getType()->isSigned();
3996 bool isUnsignedShift = !isSignedShift;
3998 // See if we can simplify any instructions used by the instruction whose sole
3999 // purpose is to compute bits we don't care about.
4000 uint64_t KnownZero, KnownOne;
4001 if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
4002 KnownZero, KnownOne))
4005 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
4006 // of a signed value.
4008 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
4009 if (Op1->getValue() >= TypeBits) {
4010 if (isUnsignedShift || isLeftShift)
4011 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
4013 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
4018 // ((X*C1) << C2) == (X * (C1 << C2))
4019 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
4020 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
4021 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
4022 return BinaryOperator::createMul(BO->getOperand(0),
4023 ConstantExpr::getShl(BOOp, Op1));
4025 // Try to fold constant and into select arguments.
4026 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
4027 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
4029 if (isa<PHINode>(Op0))
4030 if (Instruction *NV = FoldOpIntoPhi(I))
4033 if (Op0->hasOneUse()) {
4034 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
4035 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
4038 switch (Op0BO->getOpcode()) {
4040 case Instruction::Add:
4041 case Instruction::And:
4042 case Instruction::Or:
4043 case Instruction::Xor:
4044 // These operators commute.
4045 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
4046 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
4047 match(Op0BO->getOperand(1),
4048 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
4049 Instruction *YS = new ShiftInst(Instruction::Shl,
4050 Op0BO->getOperand(0), Op1,
4052 InsertNewInstBefore(YS, I); // (Y << C)
4054 BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
4055 Op0BO->getOperand(1)->getName());
4056 InsertNewInstBefore(X, I); // (X + (Y << C))
4057 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
4058 C2 = ConstantExpr::getShl(C2, Op1);
4059 return BinaryOperator::createAnd(X, C2);
4062 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
4063 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
4064 match(Op0BO->getOperand(1),
4065 m_And(m_Shr(m_Value(V1), m_Value(V2)),
4066 m_ConstantInt(CC))) && V2 == Op1 &&
4067 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
4068 Instruction *YS = new ShiftInst(Instruction::Shl,
4069 Op0BO->getOperand(0), Op1,
4071 InsertNewInstBefore(YS, I); // (Y << C)
4073 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
4074 V1->getName()+".mask");
4075 InsertNewInstBefore(XM, I); // X & (CC << C)
4077 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
4081 case Instruction::Sub:
4082 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
4083 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
4084 match(Op0BO->getOperand(0),
4085 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
4086 Instruction *YS = new ShiftInst(Instruction::Shl,
4087 Op0BO->getOperand(1), Op1,
4089 InsertNewInstBefore(YS, I); // (Y << C)
4091 BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
4092 Op0BO->getOperand(0)->getName());
4093 InsertNewInstBefore(X, I); // (X + (Y << C))
4094 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
4095 C2 = ConstantExpr::getShl(C2, Op1);
4096 return BinaryOperator::createAnd(X, C2);
4099 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
4100 match(Op0BO->getOperand(0),
4101 m_And(m_Shr(m_Value(V1), m_Value(V2)),
4102 m_ConstantInt(CC))) && V2 == Op1 &&
4103 cast<BinaryOperator>(Op0BO->getOperand(0))
4104 ->getOperand(0)->hasOneUse()) {
4105 Instruction *YS = new ShiftInst(Instruction::Shl,
4106 Op0BO->getOperand(1), Op1,
4108 InsertNewInstBefore(YS, I); // (Y << C)
4110 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
4111 V1->getName()+".mask");
4112 InsertNewInstBefore(XM, I); // X & (CC << C)
4114 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
4121 // If the operand is an bitwise operator with a constant RHS, and the
4122 // shift is the only use, we can pull it out of the shift.
4123 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
4124 bool isValid = true; // Valid only for And, Or, Xor
4125 bool highBitSet = false; // Transform if high bit of constant set?
4127 switch (Op0BO->getOpcode()) {
4128 default: isValid = false; break; // Do not perform transform!
4129 case Instruction::Add:
4130 isValid = isLeftShift;
4132 case Instruction::Or:
4133 case Instruction::Xor:
4136 case Instruction::And:
4141 // If this is a signed shift right, and the high bit is modified
4142 // by the logical operation, do not perform the transformation.
4143 // The highBitSet boolean indicates the value of the high bit of
4144 // the constant which would cause it to be modified for this
4147 if (isValid && !isLeftShift && isSignedShift) {
4148 uint64_t Val = Op0C->getRawValue();
4149 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
4153 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
4155 Instruction *NewShift =
4156 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), Op1,
4159 InsertNewInstBefore(NewShift, I);
4161 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
4168 // Find out if this is a shift of a shift by a constant.
4169 ShiftInst *ShiftOp = 0;
4170 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
4172 else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
4173 // If this is a noop-integer case of a shift instruction, use the shift.
4174 if (CI->getOperand(0)->getType()->isInteger() &&
4175 CI->getOperand(0)->getType()->getPrimitiveSizeInBits() ==
4176 CI->getType()->getPrimitiveSizeInBits() &&
4177 isa<ShiftInst>(CI->getOperand(0))) {
4178 ShiftOp = cast<ShiftInst>(CI->getOperand(0));
4182 if (ShiftOp && isa<ConstantUInt>(ShiftOp->getOperand(1))) {
4183 // Find the operands and properties of the input shift. Note that the
4184 // signedness of the input shift may differ from the current shift if there
4185 // is a noop cast between the two.
4186 bool isShiftOfLeftShift = ShiftOp->getOpcode() == Instruction::Shl;
4187 bool isShiftOfSignedShift = ShiftOp->getType()->isSigned();
4188 bool isShiftOfUnsignedShift = !isShiftOfSignedShift;
4190 ConstantUInt *ShiftAmt1C = cast<ConstantUInt>(ShiftOp->getOperand(1));
4192 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
4193 unsigned ShiftAmt2 = (unsigned)Op1->getValue();
4195 // Check for (A << c1) << c2 and (A >> c1) >> c2.
4196 if (isLeftShift == isShiftOfLeftShift) {
4197 // Do not fold these shifts if the first one is signed and the second one
4198 // is unsigned and this is a right shift. Further, don't do any folding
4200 if (isShiftOfSignedShift && isUnsignedShift && !isLeftShift)
4203 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
4204 if (Amt > Op0->getType()->getPrimitiveSizeInBits())
4205 Amt = Op0->getType()->getPrimitiveSizeInBits();
4207 Value *Op = ShiftOp->getOperand(0);
4208 if (isShiftOfSignedShift != isSignedShift)
4209 Op = InsertNewInstBefore(new CastInst(Op, I.getType(), "tmp"), I);
4210 return new ShiftInst(I.getOpcode(), Op,
4211 ConstantUInt::get(Type::UByteTy, Amt));
4214 // Check for (A << c1) >> c2 or (A >> c1) << c2. If we are dealing with
4215 // signed types, we can only support the (A >> c1) << c2 configuration,
4216 // because it can not turn an arbitrary bit of A into a sign bit.
4217 if (isUnsignedShift || isLeftShift) {
4218 // Calculate bitmask for what gets shifted off the edge.
4219 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
4221 C = ConstantExpr::getShl(C, ShiftAmt1C);
4223 C = ConstantExpr::getUShr(C, ShiftAmt1C);
4225 Value *Op = ShiftOp->getOperand(0);
4226 if (isShiftOfSignedShift != isSignedShift)
4227 Op = InsertNewInstBefore(new CastInst(Op, I.getType(),Op->getName()),I);
4230 BinaryOperator::createAnd(Op, C, Op->getName()+".mask");
4231 InsertNewInstBefore(Mask, I);
4233 // Figure out what flavor of shift we should use...
4234 if (ShiftAmt1 == ShiftAmt2) {
4235 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
4236 } else if (ShiftAmt1 < ShiftAmt2) {
4237 return new ShiftInst(I.getOpcode(), Mask,
4238 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
4239 } else if (isShiftOfUnsignedShift || isShiftOfLeftShift) {
4240 if (isShiftOfUnsignedShift && !isShiftOfLeftShift && isSignedShift) {
4241 // Make sure to emit an unsigned shift right, not a signed one.
4242 Mask = InsertNewInstBefore(new CastInst(Mask,
4243 Mask->getType()->getUnsignedVersion(),
4245 Mask = new ShiftInst(Instruction::Shr, Mask,
4246 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
4247 InsertNewInstBefore(Mask, I);
4248 return new CastInst(Mask, I.getType());
4250 return new ShiftInst(ShiftOp->getOpcode(), Mask,
4251 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
4254 // (X >>s C1) << C2 where C1 > C2 === (X >>s (C1-C2)) & mask
4255 Op = InsertNewInstBefore(new CastInst(Mask,
4256 I.getType()->getSignedVersion(),
4257 Mask->getName()), I);
4258 Instruction *Shift =
4259 new ShiftInst(ShiftOp->getOpcode(), Op,
4260 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
4261 InsertNewInstBefore(Shift, I);
4263 C = ConstantIntegral::getAllOnesValue(Shift->getType());
4264 C = ConstantExpr::getShl(C, Op1);
4265 Mask = BinaryOperator::createAnd(Shift, C, Op->getName()+".mask");
4266 InsertNewInstBefore(Mask, I);
4267 return new CastInst(Mask, I.getType());
4270 // We can handle signed (X << C1) >>s C2 if it's a sign extend. In
4271 // this case, C1 == C2 and C1 is 8, 16, or 32.
4272 if (ShiftAmt1 == ShiftAmt2) {
4273 const Type *SExtType = 0;
4274 switch (ShiftAmt1) {
4275 case 8 : SExtType = Type::SByteTy; break;
4276 case 16: SExtType = Type::ShortTy; break;
4277 case 32: SExtType = Type::IntTy; break;
4281 Instruction *NewTrunc = new CastInst(ShiftOp->getOperand(0),
4283 InsertNewInstBefore(NewTrunc, I);
4284 return new CastInst(NewTrunc, I.getType());
4299 /// getCastType - In the future, we will split the cast instruction into these
4300 /// various types. Until then, we have to do the analysis here.
4301 static CastType getCastType(const Type *Src, const Type *Dest) {
4302 assert(Src->isIntegral() && Dest->isIntegral() &&
4303 "Only works on integral types!");
4304 unsigned SrcSize = Src->getPrimitiveSizeInBits();
4305 unsigned DestSize = Dest->getPrimitiveSizeInBits();
4307 if (SrcSize == DestSize) return Noop;
4308 if (SrcSize > DestSize) return Truncate;
4309 if (Src->isSigned()) return Signext;
4314 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
4317 static bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
4318 const Type *DstTy, TargetData *TD) {
4320 // It is legal to eliminate the instruction if casting A->B->A if the sizes
4321 // are identical and the bits don't get reinterpreted (for example
4322 // int->float->int would not be allowed).
4323 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
4326 // If we are casting between pointer and integer types, treat pointers as
4327 // integers of the appropriate size for the code below.
4328 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
4329 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
4330 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
4332 // Allow free casting and conversion of sizes as long as the sign doesn't
4334 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
4335 CastType FirstCast = getCastType(SrcTy, MidTy);
4336 CastType SecondCast = getCastType(MidTy, DstTy);
4338 // Capture the effect of these two casts. If the result is a legal cast,
4339 // the CastType is stored here, otherwise a special code is used.
4340 static const unsigned CastResult[] = {
4341 // First cast is noop
4343 // First cast is a truncate
4344 1, 1, 4, 4, // trunc->extend is not safe to eliminate
4345 // First cast is a sign ext
4346 2, 5, 2, 4, // signext->zeroext never ok
4347 // First cast is a zero ext
4351 unsigned Result = CastResult[FirstCast*4+SecondCast];
4353 default: assert(0 && "Illegal table value!");
4358 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
4359 // truncates, we could eliminate more casts.
4360 return (unsigned)getCastType(SrcTy, DstTy) == Result;
4362 return false; // Not possible to eliminate this here.
4364 // Sign or zero extend followed by truncate is always ok if the result
4365 // is a truncate or noop.
4366 CastType ResultCast = getCastType(SrcTy, DstTy);
4367 if (ResultCast == Noop || ResultCast == Truncate)
4369 // Otherwise we are still growing the value, we are only safe if the
4370 // result will match the sign/zeroextendness of the result.
4371 return ResultCast == FirstCast;
4375 // If this is a cast from 'float -> double -> integer', cast from
4376 // 'float -> integer' directly, as the value isn't changed by the
4377 // float->double conversion.
4378 if (SrcTy->isFloatingPoint() && MidTy->isFloatingPoint() &&
4379 DstTy->isIntegral() &&
4380 SrcTy->getPrimitiveSize() < MidTy->getPrimitiveSize())
4386 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
4387 if (V->getType() == Ty || isa<Constant>(V)) return false;
4388 if (const CastInst *CI = dyn_cast<CastInst>(V))
4389 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
4395 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
4396 /// InsertBefore instruction. This is specialized a bit to avoid inserting
4397 /// casts that are known to not do anything...
4399 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
4400 Instruction *InsertBefore) {
4401 if (V->getType() == DestTy) return V;
4402 if (Constant *C = dyn_cast<Constant>(V))
4403 return ConstantExpr::getCast(C, DestTy);
4405 CastInst *CI = new CastInst(V, DestTy, V->getName());
4406 InsertNewInstBefore(CI, *InsertBefore);
4410 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
4411 /// expression. If so, decompose it, returning some value X, such that Val is
4414 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
4416 assert(Val->getType() == Type::UIntTy && "Unexpected allocation size type!");
4417 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(Val)) {
4418 Offset = CI->getValue();
4420 return ConstantUInt::get(Type::UIntTy, 0);
4421 } else if (Instruction *I = dyn_cast<Instruction>(Val)) {
4422 if (I->getNumOperands() == 2) {
4423 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I->getOperand(1))) {
4424 if (I->getOpcode() == Instruction::Shl) {
4425 // This is a value scaled by '1 << the shift amt'.
4426 Scale = 1U << CUI->getValue();
4428 return I->getOperand(0);
4429 } else if (I->getOpcode() == Instruction::Mul) {
4430 // This value is scaled by 'CUI'.
4431 Scale = CUI->getValue();
4433 return I->getOperand(0);
4434 } else if (I->getOpcode() == Instruction::Add) {
4435 // We have X+C. Check to see if we really have (X*C2)+C1, where C1 is
4438 Value *SubVal = DecomposeSimpleLinearExpr(I->getOperand(0), SubScale,
4440 Offset += CUI->getValue();
4441 if (SubScale > 1 && (Offset % SubScale == 0)) {
4450 // Otherwise, we can't look past this.
4457 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
4458 /// try to eliminate the cast by moving the type information into the alloc.
4459 Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
4460 AllocationInst &AI) {
4461 const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
4462 if (!PTy) return 0; // Not casting the allocation to a pointer type.
4464 // Remove any uses of AI that are dead.
4465 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
4466 std::vector<Instruction*> DeadUsers;
4467 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
4468 Instruction *User = cast<Instruction>(*UI++);
4469 if (isInstructionTriviallyDead(User)) {
4470 while (UI != E && *UI == User)
4471 ++UI; // If this instruction uses AI more than once, don't break UI.
4473 // Add operands to the worklist.
4474 AddUsesToWorkList(*User);
4476 DEBUG(std::cerr << "IC: DCE: " << *User);
4478 User->eraseFromParent();
4479 removeFromWorkList(User);
4483 // Get the type really allocated and the type casted to.
4484 const Type *AllocElTy = AI.getAllocatedType();
4485 const Type *CastElTy = PTy->getElementType();
4486 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
4488 unsigned AllocElTyAlign = TD->getTypeSize(AllocElTy);
4489 unsigned CastElTyAlign = TD->getTypeSize(CastElTy);
4490 if (CastElTyAlign < AllocElTyAlign) return 0;
4492 // If the allocation has multiple uses, only promote it if we are strictly
4493 // increasing the alignment of the resultant allocation. If we keep it the
4494 // same, we open the door to infinite loops of various kinds.
4495 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
4497 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
4498 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
4499 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
4501 // See if we can satisfy the modulus by pulling a scale out of the array
4503 unsigned ArraySizeScale, ArrayOffset;
4504 Value *NumElements = // See if the array size is a decomposable linear expr.
4505 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
4507 // If we can now satisfy the modulus, by using a non-1 scale, we really can
4509 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
4510 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
4512 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
4517 Amt = ConstantUInt::get(Type::UIntTy, Scale);
4518 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements))
4519 Amt = ConstantExpr::getMul(CI, cast<ConstantUInt>(Amt));
4520 else if (Scale != 1) {
4521 Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
4522 Amt = InsertNewInstBefore(Tmp, AI);
4526 if (unsigned Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
4527 Value *Off = ConstantUInt::get(Type::UIntTy, Offset);
4528 Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
4529 Amt = InsertNewInstBefore(Tmp, AI);
4532 std::string Name = AI.getName(); AI.setName("");
4533 AllocationInst *New;
4534 if (isa<MallocInst>(AI))
4535 New = new MallocInst(CastElTy, Amt, AI.getAlignment(), Name);
4537 New = new AllocaInst(CastElTy, Amt, AI.getAlignment(), Name);
4538 InsertNewInstBefore(New, AI);
4540 // If the allocation has multiple uses, insert a cast and change all things
4541 // that used it to use the new cast. This will also hack on CI, but it will
4543 if (!AI.hasOneUse()) {
4544 AddUsesToWorkList(AI);
4545 CastInst *NewCast = new CastInst(New, AI.getType(), "tmpcast");
4546 InsertNewInstBefore(NewCast, AI);
4547 AI.replaceAllUsesWith(NewCast);
4549 return ReplaceInstUsesWith(CI, New);
4553 // CastInst simplification
4555 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
4556 Value *Src = CI.getOperand(0);
4558 // If the user is casting a value to the same type, eliminate this cast
4560 if (CI.getType() == Src->getType())
4561 return ReplaceInstUsesWith(CI, Src);
4563 if (isa<UndefValue>(Src)) // cast undef -> undef
4564 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
4566 // If casting the result of another cast instruction, try to eliminate this
4569 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
4570 Value *A = CSrc->getOperand(0);
4571 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
4572 CI.getType(), TD)) {
4573 // This instruction now refers directly to the cast's src operand. This
4574 // has a good chance of making CSrc dead.
4575 CI.setOperand(0, CSrc->getOperand(0));
4579 // If this is an A->B->A cast, and we are dealing with integral types, try
4580 // to convert this into a logical 'and' instruction.
4582 if (A->getType()->isInteger() &&
4583 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
4584 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
4585 CSrc->getType()->getPrimitiveSizeInBits() <
4586 CI.getType()->getPrimitiveSizeInBits()&&
4587 A->getType()->getPrimitiveSizeInBits() ==
4588 CI.getType()->getPrimitiveSizeInBits()) {
4589 assert(CSrc->getType() != Type::ULongTy &&
4590 "Cannot have type bigger than ulong!");
4591 uint64_t AndValue = CSrc->getType()->getIntegralTypeMask();
4592 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
4594 AndOp = ConstantExpr::getCast(AndOp, A->getType());
4595 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
4596 if (And->getType() != CI.getType()) {
4597 And->setName(CSrc->getName()+".mask");
4598 InsertNewInstBefore(And, CI);
4599 And = new CastInst(And, CI.getType());
4605 // If this is a cast to bool, turn it into the appropriate setne instruction.
4606 if (CI.getType() == Type::BoolTy)
4607 return BinaryOperator::createSetNE(CI.getOperand(0),
4608 Constant::getNullValue(CI.getOperand(0)->getType()));
4610 // See if we can simplify any instructions used by the LHS whose sole
4611 // purpose is to compute bits we don't care about.
4612 if (CI.getType()->isInteger() && CI.getOperand(0)->getType()->isIntegral()) {
4613 uint64_t KnownZero, KnownOne;
4614 if (SimplifyDemandedBits(&CI, CI.getType()->getIntegralTypeMask(),
4615 KnownZero, KnownOne))
4619 // If casting the result of a getelementptr instruction with no offset, turn
4620 // this into a cast of the original pointer!
4622 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
4623 bool AllZeroOperands = true;
4624 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
4625 if (!isa<Constant>(GEP->getOperand(i)) ||
4626 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
4627 AllZeroOperands = false;
4630 if (AllZeroOperands) {
4631 CI.setOperand(0, GEP->getOperand(0));
4636 // If we are casting a malloc or alloca to a pointer to a type of the same
4637 // size, rewrite the allocation instruction to allocate the "right" type.
4639 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
4640 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
4643 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
4644 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
4646 if (isa<PHINode>(Src))
4647 if (Instruction *NV = FoldOpIntoPhi(CI))
4650 // If the source value is an instruction with only this use, we can attempt to
4651 // propagate the cast into the instruction. Also, only handle integral types
4653 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
4654 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
4655 CI.getType()->isInteger()) { // Don't mess with casts to bool here
4656 const Type *DestTy = CI.getType();
4657 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
4658 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
4660 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
4661 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
4663 switch (SrcI->getOpcode()) {
4664 case Instruction::Add:
4665 case Instruction::Mul:
4666 case Instruction::And:
4667 case Instruction::Or:
4668 case Instruction::Xor:
4669 // If we are discarding information, or just changing the sign, rewrite.
4670 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
4671 // Don't insert two casts if they cannot be eliminated. We allow two
4672 // casts to be inserted if the sizes are the same. This could only be
4673 // converting signedness, which is a noop.
4674 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
4675 !ValueRequiresCast(Op0, DestTy, TD)) {
4676 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4677 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
4678 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
4679 ->getOpcode(), Op0c, Op1c);
4683 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
4684 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
4685 Op1 == ConstantBool::True &&
4686 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
4687 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
4688 return BinaryOperator::createXor(New,
4689 ConstantInt::get(CI.getType(), 1));
4692 case Instruction::Shl:
4693 // Allow changing the sign of the source operand. Do not allow changing
4694 // the size of the shift, UNLESS the shift amount is a constant. We
4695 // mush not change variable sized shifts to a smaller size, because it
4696 // is undefined to shift more bits out than exist in the value.
4697 if (DestBitSize == SrcBitSize ||
4698 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
4699 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4700 return new ShiftInst(Instruction::Shl, Op0c, Op1);
4703 case Instruction::Shr:
4704 // If this is a signed shr, and if all bits shifted in are about to be
4705 // truncated off, turn it into an unsigned shr to allow greater
4707 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
4708 isa<ConstantInt>(Op1)) {
4709 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
4710 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
4711 // Convert to unsigned.
4712 Value *N1 = InsertOperandCastBefore(Op0,
4713 Op0->getType()->getUnsignedVersion(), &CI);
4714 // Insert the new shift, which is now unsigned.
4715 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
4716 Op1, Src->getName()), CI);
4717 return new CastInst(N1, CI.getType());
4722 case Instruction::SetNE:
4723 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4724 if (Op1C->getRawValue() == 0) {
4725 // If the input only has the low bit set, simplify directly.
4727 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4728 // cast (X != 0) to int --> X if X&~1 == 0
4729 if (MaskedValueIsZero(Op0,
4730 cast<ConstantIntegral>(Not1)->getZExtValue())) {
4731 if (CI.getType() == Op0->getType())
4732 return ReplaceInstUsesWith(CI, Op0);
4734 return new CastInst(Op0, CI.getType());
4737 // If the input is an and with a single bit, shift then simplify.
4738 ConstantInt *AndRHS;
4739 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
4740 if (AndRHS->getRawValue() &&
4741 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
4742 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
4743 // Perform an unsigned shr by shiftamt. Convert input to
4744 // unsigned if it is signed.
4746 if (In->getType()->isSigned())
4747 In = InsertNewInstBefore(new CastInst(In,
4748 In->getType()->getUnsignedVersion(), In->getName()),CI);
4749 // Insert the shift to put the result in the low bit.
4750 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
4751 ConstantInt::get(Type::UByteTy, ShiftAmt),
4752 In->getName()+".lobit"), CI);
4753 if (CI.getType() == In->getType())
4754 return ReplaceInstUsesWith(CI, In);
4756 return new CastInst(In, CI.getType());
4761 case Instruction::SetEQ:
4762 // We if we are just checking for a seteq of a single bit and casting it
4763 // to an integer. If so, shift the bit to the appropriate place then
4764 // cast to integer to avoid the comparison.
4765 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4766 // Is Op1C a power of two or zero?
4767 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
4768 // cast (X == 1) to int -> X iff X has only the low bit set.
4769 if (Op1C->getRawValue() == 1) {
4771 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4772 if (MaskedValueIsZero(Op0,
4773 cast<ConstantIntegral>(Not1)->getZExtValue())) {
4774 if (CI.getType() == Op0->getType())
4775 return ReplaceInstUsesWith(CI, Op0);
4777 return new CastInst(Op0, CI.getType());
4789 /// GetSelectFoldableOperands - We want to turn code that looks like this:
4791 /// %D = select %cond, %C, %A
4793 /// %C = select %cond, %B, 0
4796 /// Assuming that the specified instruction is an operand to the select, return
4797 /// a bitmask indicating which operands of this instruction are foldable if they
4798 /// equal the other incoming value of the select.
4800 static unsigned GetSelectFoldableOperands(Instruction *I) {
4801 switch (I->getOpcode()) {
4802 case Instruction::Add:
4803 case Instruction::Mul:
4804 case Instruction::And:
4805 case Instruction::Or:
4806 case Instruction::Xor:
4807 return 3; // Can fold through either operand.
4808 case Instruction::Sub: // Can only fold on the amount subtracted.
4809 case Instruction::Shl: // Can only fold on the shift amount.
4810 case Instruction::Shr:
4813 return 0; // Cannot fold
4817 /// GetSelectFoldableConstant - For the same transformation as the previous
4818 /// function, return the identity constant that goes into the select.
4819 static Constant *GetSelectFoldableConstant(Instruction *I) {
4820 switch (I->getOpcode()) {
4821 default: assert(0 && "This cannot happen!"); abort();
4822 case Instruction::Add:
4823 case Instruction::Sub:
4824 case Instruction::Or:
4825 case Instruction::Xor:
4826 return Constant::getNullValue(I->getType());
4827 case Instruction::Shl:
4828 case Instruction::Shr:
4829 return Constant::getNullValue(Type::UByteTy);
4830 case Instruction::And:
4831 return ConstantInt::getAllOnesValue(I->getType());
4832 case Instruction::Mul:
4833 return ConstantInt::get(I->getType(), 1);
4837 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
4838 /// have the same opcode and only one use each. Try to simplify this.
4839 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
4841 if (TI->getNumOperands() == 1) {
4842 // If this is a non-volatile load or a cast from the same type,
4844 if (TI->getOpcode() == Instruction::Cast) {
4845 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
4848 return 0; // unknown unary op.
4851 // Fold this by inserting a select from the input values.
4852 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
4853 FI->getOperand(0), SI.getName()+".v");
4854 InsertNewInstBefore(NewSI, SI);
4855 return new CastInst(NewSI, TI->getType());
4858 // Only handle binary operators here.
4859 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
4862 // Figure out if the operations have any operands in common.
4863 Value *MatchOp, *OtherOpT, *OtherOpF;
4865 if (TI->getOperand(0) == FI->getOperand(0)) {
4866 MatchOp = TI->getOperand(0);
4867 OtherOpT = TI->getOperand(1);
4868 OtherOpF = FI->getOperand(1);
4869 MatchIsOpZero = true;
4870 } else if (TI->getOperand(1) == FI->getOperand(1)) {
4871 MatchOp = TI->getOperand(1);
4872 OtherOpT = TI->getOperand(0);
4873 OtherOpF = FI->getOperand(0);
4874 MatchIsOpZero = false;
4875 } else if (!TI->isCommutative()) {
4877 } else if (TI->getOperand(0) == FI->getOperand(1)) {
4878 MatchOp = TI->getOperand(0);
4879 OtherOpT = TI->getOperand(1);
4880 OtherOpF = FI->getOperand(0);
4881 MatchIsOpZero = true;
4882 } else if (TI->getOperand(1) == FI->getOperand(0)) {
4883 MatchOp = TI->getOperand(1);
4884 OtherOpT = TI->getOperand(0);
4885 OtherOpF = FI->getOperand(1);
4886 MatchIsOpZero = true;
4891 // If we reach here, they do have operations in common.
4892 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4893 OtherOpF, SI.getName()+".v");
4894 InsertNewInstBefore(NewSI, SI);
4896 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4898 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4900 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4903 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4905 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4909 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4910 Value *CondVal = SI.getCondition();
4911 Value *TrueVal = SI.getTrueValue();
4912 Value *FalseVal = SI.getFalseValue();
4914 // select true, X, Y -> X
4915 // select false, X, Y -> Y
4916 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4917 if (C == ConstantBool::True)
4918 return ReplaceInstUsesWith(SI, TrueVal);
4920 assert(C == ConstantBool::False);
4921 return ReplaceInstUsesWith(SI, FalseVal);
4924 // select C, X, X -> X
4925 if (TrueVal == FalseVal)
4926 return ReplaceInstUsesWith(SI, TrueVal);
4928 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4929 return ReplaceInstUsesWith(SI, FalseVal);
4930 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4931 return ReplaceInstUsesWith(SI, TrueVal);
4932 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4933 if (isa<Constant>(TrueVal))
4934 return ReplaceInstUsesWith(SI, TrueVal);
4936 return ReplaceInstUsesWith(SI, FalseVal);
4939 if (SI.getType() == Type::BoolTy)
4940 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4941 if (C == ConstantBool::True) {
4942 // Change: A = select B, true, C --> A = or B, C
4943 return BinaryOperator::createOr(CondVal, FalseVal);
4945 // Change: A = select B, false, C --> A = and !B, C
4947 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4948 "not."+CondVal->getName()), SI);
4949 return BinaryOperator::createAnd(NotCond, FalseVal);
4951 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4952 if (C == ConstantBool::False) {
4953 // Change: A = select B, C, false --> A = and B, C
4954 return BinaryOperator::createAnd(CondVal, TrueVal);
4956 // Change: A = select B, C, true --> A = or !B, C
4958 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4959 "not."+CondVal->getName()), SI);
4960 return BinaryOperator::createOr(NotCond, TrueVal);
4964 // Selecting between two integer constants?
4965 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4966 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4967 // select C, 1, 0 -> cast C to int
4968 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4969 return new CastInst(CondVal, SI.getType());
4970 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4971 // select C, 0, 1 -> cast !C to int
4973 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4974 "not."+CondVal->getName()), SI);
4975 return new CastInst(NotCond, SI.getType());
4978 // If one of the constants is zero (we know they can't both be) and we
4979 // have a setcc instruction with zero, and we have an 'and' with the
4980 // non-constant value, eliminate this whole mess. This corresponds to
4981 // cases like this: ((X & 27) ? 27 : 0)
4982 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4983 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4984 if ((IC->getOpcode() == Instruction::SetEQ ||
4985 IC->getOpcode() == Instruction::SetNE) &&
4986 isa<ConstantInt>(IC->getOperand(1)) &&
4987 cast<Constant>(IC->getOperand(1))->isNullValue())
4988 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4989 if (ICA->getOpcode() == Instruction::And &&
4990 isa<ConstantInt>(ICA->getOperand(1)) &&
4991 (ICA->getOperand(1) == TrueValC ||
4992 ICA->getOperand(1) == FalseValC) &&
4993 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
4994 // Okay, now we know that everything is set up, we just don't
4995 // know whether we have a setne or seteq and whether the true or
4996 // false val is the zero.
4997 bool ShouldNotVal = !TrueValC->isNullValue();
4998 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
5001 V = InsertNewInstBefore(BinaryOperator::create(
5002 Instruction::Xor, V, ICA->getOperand(1)), SI);
5003 return ReplaceInstUsesWith(SI, V);
5007 // See if we are selecting two values based on a comparison of the two values.
5008 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
5009 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
5010 // Transform (X == Y) ? X : Y -> Y
5011 if (SCI->getOpcode() == Instruction::SetEQ)
5012 return ReplaceInstUsesWith(SI, FalseVal);
5013 // Transform (X != Y) ? X : Y -> X
5014 if (SCI->getOpcode() == Instruction::SetNE)
5015 return ReplaceInstUsesWith(SI, TrueVal);
5016 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
5018 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
5019 // Transform (X == Y) ? Y : X -> X
5020 if (SCI->getOpcode() == Instruction::SetEQ)
5021 return ReplaceInstUsesWith(SI, FalseVal);
5022 // Transform (X != Y) ? Y : X -> Y
5023 if (SCI->getOpcode() == Instruction::SetNE)
5024 return ReplaceInstUsesWith(SI, TrueVal);
5025 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
5029 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
5030 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
5031 if (TI->hasOneUse() && FI->hasOneUse()) {
5032 bool isInverse = false;
5033 Instruction *AddOp = 0, *SubOp = 0;
5035 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
5036 if (TI->getOpcode() == FI->getOpcode())
5037 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
5040 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
5041 // even legal for FP.
5042 if (TI->getOpcode() == Instruction::Sub &&
5043 FI->getOpcode() == Instruction::Add) {
5044 AddOp = FI; SubOp = TI;
5045 } else if (FI->getOpcode() == Instruction::Sub &&
5046 TI->getOpcode() == Instruction::Add) {
5047 AddOp = TI; SubOp = FI;
5051 Value *OtherAddOp = 0;
5052 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
5053 OtherAddOp = AddOp->getOperand(1);
5054 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
5055 OtherAddOp = AddOp->getOperand(0);
5059 // So at this point we know we have:
5060 // select C, (add X, Y), (sub X, ?)
5061 // We can do the transform profitably if either 'Y' = '?' or '?' is
5063 if (SubOp->getOperand(1) == AddOp ||
5064 isa<Constant>(SubOp->getOperand(1))) {
5066 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
5067 NegVal = ConstantExpr::getNeg(C);
5069 NegVal = InsertNewInstBefore(
5070 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
5073 Value *NewTrueOp = OtherAddOp;
5074 Value *NewFalseOp = NegVal;
5076 std::swap(NewTrueOp, NewFalseOp);
5077 Instruction *NewSel =
5078 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
5080 NewSel = InsertNewInstBefore(NewSel, SI);
5081 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
5087 // See if we can fold the select into one of our operands.
5088 if (SI.getType()->isInteger()) {
5089 // See the comment above GetSelectFoldableOperands for a description of the
5090 // transformation we are doing here.
5091 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
5092 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
5093 !isa<Constant>(FalseVal))
5094 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
5095 unsigned OpToFold = 0;
5096 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
5098 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
5103 Constant *C = GetSelectFoldableConstant(TVI);
5104 std::string Name = TVI->getName(); TVI->setName("");
5105 Instruction *NewSel =
5106 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
5108 InsertNewInstBefore(NewSel, SI);
5109 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
5110 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
5111 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
5112 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
5114 assert(0 && "Unknown instruction!!");
5119 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
5120 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
5121 !isa<Constant>(TrueVal))
5122 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
5123 unsigned OpToFold = 0;
5124 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
5126 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
5131 Constant *C = GetSelectFoldableConstant(FVI);
5132 std::string Name = FVI->getName(); FVI->setName("");
5133 Instruction *NewSel =
5134 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
5136 InsertNewInstBefore(NewSel, SI);
5137 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
5138 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
5139 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
5140 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
5142 assert(0 && "Unknown instruction!!");
5148 if (BinaryOperator::isNot(CondVal)) {
5149 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
5150 SI.setOperand(1, FalseVal);
5151 SI.setOperand(2, TrueVal);
5159 /// visitCallInst - CallInst simplification. This mostly only handles folding
5160 /// of intrinsic instructions. For normal calls, it allows visitCallSite to do
5161 /// the heavy lifting.
5163 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
5164 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
5165 if (!II) return visitCallSite(&CI);
5167 // Intrinsics cannot occur in an invoke, so handle them here instead of in
5169 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
5170 bool Changed = false;
5172 // memmove/cpy/set of zero bytes is a noop.
5173 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
5174 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
5176 // FIXME: Increase alignment here.
5178 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
5179 if (CI->getRawValue() == 1) {
5180 // Replace the instruction with just byte operations. We would
5181 // transform other cases to loads/stores, but we don't know if
5182 // alignment is sufficient.
5186 // If we have a memmove and the source operation is a constant global,
5187 // then the source and dest pointers can't alias, so we can change this
5188 // into a call to memcpy.
5189 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(II))
5190 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
5191 if (GVSrc->isConstant()) {
5192 Module *M = CI.getParent()->getParent()->getParent();
5193 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
5194 CI.getCalledFunction()->getFunctionType());
5195 CI.setOperand(0, MemCpy);
5199 if (Changed) return II;
5200 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(II)) {
5201 // If this stoppoint is at the same source location as the previous
5202 // stoppoint in the chain, it is not needed.
5203 if (DbgStopPointInst *PrevSPI =
5204 dyn_cast<DbgStopPointInst>(SPI->getChain()))
5205 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
5206 SPI->getColNo() == PrevSPI->getColNo()) {
5207 SPI->replaceAllUsesWith(PrevSPI);
5208 return EraseInstFromFunction(CI);
5211 switch (II->getIntrinsicID()) {
5213 case Intrinsic::stackrestore: {
5214 // If the save is right next to the restore, remove the restore. This can
5215 // happen when variable allocas are DCE'd.
5216 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
5217 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
5218 BasicBlock::iterator BI = SS;
5220 return EraseInstFromFunction(CI);
5224 // If the stack restore is in a return/unwind block and if there are no
5225 // allocas or calls between the restore and the return, nuke the restore.
5226 TerminatorInst *TI = II->getParent()->getTerminator();
5227 if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) {
5228 BasicBlock::iterator BI = II;
5229 bool CannotRemove = false;
5230 for (++BI; &*BI != TI; ++BI) {
5231 if (isa<AllocaInst>(BI) ||
5232 (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) {
5233 CannotRemove = true;
5238 return EraseInstFromFunction(CI);
5245 return visitCallSite(II);
5248 // InvokeInst simplification
5250 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
5251 return visitCallSite(&II);
5254 // visitCallSite - Improvements for call and invoke instructions.
5256 Instruction *InstCombiner::visitCallSite(CallSite CS) {
5257 bool Changed = false;
5259 // If the callee is a constexpr cast of a function, attempt to move the cast
5260 // to the arguments of the call/invoke.
5261 if (transformConstExprCastCall(CS)) return 0;
5263 Value *Callee = CS.getCalledValue();
5265 if (Function *CalleeF = dyn_cast<Function>(Callee))
5266 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
5267 Instruction *OldCall = CS.getInstruction();
5268 // If the call and callee calling conventions don't match, this call must
5269 // be unreachable, as the call is undefined.
5270 new StoreInst(ConstantBool::True,
5271 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
5272 if (!OldCall->use_empty())
5273 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
5274 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
5275 return EraseInstFromFunction(*OldCall);
5279 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
5280 // This instruction is not reachable, just remove it. We insert a store to
5281 // undef so that we know that this code is not reachable, despite the fact
5282 // that we can't modify the CFG here.
5283 new StoreInst(ConstantBool::True,
5284 UndefValue::get(PointerType::get(Type::BoolTy)),
5285 CS.getInstruction());
5287 if (!CS.getInstruction()->use_empty())
5288 CS.getInstruction()->
5289 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
5291 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
5292 // Don't break the CFG, insert a dummy cond branch.
5293 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
5294 ConstantBool::True, II);
5296 return EraseInstFromFunction(*CS.getInstruction());
5299 const PointerType *PTy = cast<PointerType>(Callee->getType());
5300 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
5301 if (FTy->isVarArg()) {
5302 // See if we can optimize any arguments passed through the varargs area of
5304 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
5305 E = CS.arg_end(); I != E; ++I)
5306 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
5307 // If this cast does not effect the value passed through the varargs
5308 // area, we can eliminate the use of the cast.
5309 Value *Op = CI->getOperand(0);
5310 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
5317 return Changed ? CS.getInstruction() : 0;
5320 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
5321 // attempt to move the cast to the arguments of the call/invoke.
5323 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
5324 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
5325 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
5326 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
5328 Function *Callee = cast<Function>(CE->getOperand(0));
5329 Instruction *Caller = CS.getInstruction();
5331 // Okay, this is a cast from a function to a different type. Unless doing so
5332 // would cause a type conversion of one of our arguments, change this call to
5333 // be a direct call with arguments casted to the appropriate types.
5335 const FunctionType *FT = Callee->getFunctionType();
5336 const Type *OldRetTy = Caller->getType();
5338 // Check to see if we are changing the return type...
5339 if (OldRetTy != FT->getReturnType()) {
5340 if (Callee->isExternal() &&
5341 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
5342 !Caller->use_empty())
5343 return false; // Cannot transform this return value...
5345 // If the callsite is an invoke instruction, and the return value is used by
5346 // a PHI node in a successor, we cannot change the return type of the call
5347 // because there is no place to put the cast instruction (without breaking
5348 // the critical edge). Bail out in this case.
5349 if (!Caller->use_empty())
5350 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
5351 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
5353 if (PHINode *PN = dyn_cast<PHINode>(*UI))
5354 if (PN->getParent() == II->getNormalDest() ||
5355 PN->getParent() == II->getUnwindDest())
5359 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
5360 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
5362 CallSite::arg_iterator AI = CS.arg_begin();
5363 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
5364 const Type *ParamTy = FT->getParamType(i);
5365 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
5366 if (Callee->isExternal() && !isConvertible) return false;
5369 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
5370 Callee->isExternal())
5371 return false; // Do not delete arguments unless we have a function body...
5373 // Okay, we decided that this is a safe thing to do: go ahead and start
5374 // inserting cast instructions as necessary...
5375 std::vector<Value*> Args;
5376 Args.reserve(NumActualArgs);
5378 AI = CS.arg_begin();
5379 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
5380 const Type *ParamTy = FT->getParamType(i);
5381 if ((*AI)->getType() == ParamTy) {
5382 Args.push_back(*AI);
5384 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
5389 // If the function takes more arguments than the call was taking, add them
5391 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
5392 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
5394 // If we are removing arguments to the function, emit an obnoxious warning...
5395 if (FT->getNumParams() < NumActualArgs)
5396 if (!FT->isVarArg()) {
5397 std::cerr << "WARNING: While resolving call to function '"
5398 << Callee->getName() << "' arguments were dropped!\n";
5400 // Add all of the arguments in their promoted form to the arg list...
5401 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
5402 const Type *PTy = getPromotedType((*AI)->getType());
5403 if (PTy != (*AI)->getType()) {
5404 // Must promote to pass through va_arg area!
5405 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
5406 InsertNewInstBefore(Cast, *Caller);
5407 Args.push_back(Cast);
5409 Args.push_back(*AI);
5414 if (FT->getReturnType() == Type::VoidTy)
5415 Caller->setName(""); // Void type should not have a name...
5418 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
5419 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
5420 Args, Caller->getName(), Caller);
5421 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
5423 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
5424 if (cast<CallInst>(Caller)->isTailCall())
5425 cast<CallInst>(NC)->setTailCall();
5426 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
5429 // Insert a cast of the return type as necessary...
5431 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
5432 if (NV->getType() != Type::VoidTy) {
5433 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
5435 // If this is an invoke instruction, we should insert it after the first
5436 // non-phi, instruction in the normal successor block.
5437 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
5438 BasicBlock::iterator I = II->getNormalDest()->begin();
5439 while (isa<PHINode>(I)) ++I;
5440 InsertNewInstBefore(NC, *I);
5442 // Otherwise, it's a call, just insert cast right after the call instr
5443 InsertNewInstBefore(NC, *Caller);
5445 AddUsersToWorkList(*Caller);
5447 NV = UndefValue::get(Caller->getType());
5451 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
5452 Caller->replaceAllUsesWith(NV);
5453 Caller->getParent()->getInstList().erase(Caller);
5454 removeFromWorkList(Caller);
5459 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
5460 // operator and they all are only used by the PHI, PHI together their
5461 // inputs, and do the operation once, to the result of the PHI.
5462 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
5463 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
5465 // Scan the instruction, looking for input operations that can be folded away.
5466 // If all input operands to the phi are the same instruction (e.g. a cast from
5467 // the same type or "+42") we can pull the operation through the PHI, reducing
5468 // code size and simplifying code.
5469 Constant *ConstantOp = 0;
5470 const Type *CastSrcTy = 0;
5471 if (isa<CastInst>(FirstInst)) {
5472 CastSrcTy = FirstInst->getOperand(0)->getType();
5473 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
5474 // Can fold binop or shift if the RHS is a constant.
5475 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
5476 if (ConstantOp == 0) return 0;
5478 return 0; // Cannot fold this operation.
5481 // Check to see if all arguments are the same operation.
5482 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
5483 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
5484 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
5485 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
5488 if (I->getOperand(0)->getType() != CastSrcTy)
5489 return 0; // Cast operation must match.
5490 } else if (I->getOperand(1) != ConstantOp) {
5495 // Okay, they are all the same operation. Create a new PHI node of the
5496 // correct type, and PHI together all of the LHS's of the instructions.
5497 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
5498 PN.getName()+".in");
5499 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
5501 Value *InVal = FirstInst->getOperand(0);
5502 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
5504 // Add all operands to the new PHI.
5505 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
5506 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
5507 if (NewInVal != InVal)
5509 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
5514 // The new PHI unions all of the same values together. This is really
5515 // common, so we handle it intelligently here for compile-time speed.
5519 InsertNewInstBefore(NewPN, PN);
5523 // Insert and return the new operation.
5524 if (isa<CastInst>(FirstInst))
5525 return new CastInst(PhiVal, PN.getType());
5526 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
5527 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
5529 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
5530 PhiVal, ConstantOp);
5533 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
5535 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
5536 if (PN->use_empty()) return true;
5537 if (!PN->hasOneUse()) return false;
5539 // Remember this node, and if we find the cycle, return.
5540 if (!PotentiallyDeadPHIs.insert(PN).second)
5543 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
5544 return DeadPHICycle(PU, PotentiallyDeadPHIs);
5549 // PHINode simplification
5551 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
5552 if (Value *V = PN.hasConstantValue())
5553 return ReplaceInstUsesWith(PN, V);
5555 // If the only user of this instruction is a cast instruction, and all of the
5556 // incoming values are constants, change this PHI to merge together the casted
5559 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
5560 if (CI->getType() != PN.getType()) { // noop casts will be folded
5561 bool AllConstant = true;
5562 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
5563 if (!isa<Constant>(PN.getIncomingValue(i))) {
5564 AllConstant = false;
5568 // Make a new PHI with all casted values.
5569 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
5570 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
5571 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
5572 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
5573 PN.getIncomingBlock(i));
5576 // Update the cast instruction.
5577 CI->setOperand(0, New);
5578 WorkList.push_back(CI); // revisit the cast instruction to fold.
5579 WorkList.push_back(New); // Make sure to revisit the new Phi
5580 return &PN; // PN is now dead!
5584 // If all PHI operands are the same operation, pull them through the PHI,
5585 // reducing code size.
5586 if (isa<Instruction>(PN.getIncomingValue(0)) &&
5587 PN.getIncomingValue(0)->hasOneUse())
5588 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
5591 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
5592 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
5593 // PHI)... break the cycle.
5595 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
5596 std::set<PHINode*> PotentiallyDeadPHIs;
5597 PotentiallyDeadPHIs.insert(&PN);
5598 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
5599 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
5605 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
5606 Instruction *InsertPoint,
5608 unsigned PS = IC->getTargetData().getPointerSize();
5609 const Type *VTy = V->getType();
5610 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
5611 // We must insert a cast to ensure we sign-extend.
5612 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
5613 V->getName()), *InsertPoint);
5614 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
5619 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
5620 Value *PtrOp = GEP.getOperand(0);
5621 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
5622 // If so, eliminate the noop.
5623 if (GEP.getNumOperands() == 1)
5624 return ReplaceInstUsesWith(GEP, PtrOp);
5626 if (isa<UndefValue>(GEP.getOperand(0)))
5627 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
5629 bool HasZeroPointerIndex = false;
5630 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
5631 HasZeroPointerIndex = C->isNullValue();
5633 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
5634 return ReplaceInstUsesWith(GEP, PtrOp);
5636 // Eliminate unneeded casts for indices.
5637 bool MadeChange = false;
5638 gep_type_iterator GTI = gep_type_begin(GEP);
5639 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
5640 if (isa<SequentialType>(*GTI)) {
5641 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
5642 Value *Src = CI->getOperand(0);
5643 const Type *SrcTy = Src->getType();
5644 const Type *DestTy = CI->getType();
5645 if (Src->getType()->isInteger()) {
5646 if (SrcTy->getPrimitiveSizeInBits() ==
5647 DestTy->getPrimitiveSizeInBits()) {
5648 // We can always eliminate a cast from ulong or long to the other.
5649 // We can always eliminate a cast from uint to int or the other on
5650 // 32-bit pointer platforms.
5651 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
5653 GEP.setOperand(i, Src);
5655 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
5656 SrcTy->getPrimitiveSize() == 4) {
5657 // We can always eliminate a cast from int to [u]long. We can
5658 // eliminate a cast from uint to [u]long iff the target is a 32-bit
5660 if (SrcTy->isSigned() ||
5661 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
5663 GEP.setOperand(i, Src);
5668 // If we are using a wider index than needed for this platform, shrink it
5669 // to what we need. If the incoming value needs a cast instruction,
5670 // insert it. This explicit cast can make subsequent optimizations more
5672 Value *Op = GEP.getOperand(i);
5673 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
5674 if (Constant *C = dyn_cast<Constant>(Op)) {
5675 GEP.setOperand(i, ConstantExpr::getCast(C,
5676 TD->getIntPtrType()->getSignedVersion()));
5679 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
5680 Op->getName()), GEP);
5681 GEP.setOperand(i, Op);
5685 // If this is a constant idx, make sure to canonicalize it to be a signed
5686 // operand, otherwise CSE and other optimizations are pessimized.
5687 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
5688 GEP.setOperand(i, ConstantExpr::getCast(CUI,
5689 CUI->getType()->getSignedVersion()));
5693 if (MadeChange) return &GEP;
5695 // Combine Indices - If the source pointer to this getelementptr instruction
5696 // is a getelementptr instruction, combine the indices of the two
5697 // getelementptr instructions into a single instruction.
5699 std::vector<Value*> SrcGEPOperands;
5700 if (User *Src = dyn_castGetElementPtr(PtrOp))
5701 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
5703 if (!SrcGEPOperands.empty()) {
5704 // Note that if our source is a gep chain itself that we wait for that
5705 // chain to be resolved before we perform this transformation. This
5706 // avoids us creating a TON of code in some cases.
5708 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
5709 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
5710 return 0; // Wait until our source is folded to completion.
5712 std::vector<Value *> Indices;
5714 // Find out whether the last index in the source GEP is a sequential idx.
5715 bool EndsWithSequential = false;
5716 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
5717 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
5718 EndsWithSequential = !isa<StructType>(*I);
5720 // Can we combine the two pointer arithmetics offsets?
5721 if (EndsWithSequential) {
5722 // Replace: gep (gep %P, long B), long A, ...
5723 // With: T = long A+B; gep %P, T, ...
5725 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
5726 if (SO1 == Constant::getNullValue(SO1->getType())) {
5728 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
5731 // If they aren't the same type, convert both to an integer of the
5732 // target's pointer size.
5733 if (SO1->getType() != GO1->getType()) {
5734 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
5735 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
5736 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
5737 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
5739 unsigned PS = TD->getPointerSize();
5740 if (SO1->getType()->getPrimitiveSize() == PS) {
5741 // Convert GO1 to SO1's type.
5742 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
5744 } else if (GO1->getType()->getPrimitiveSize() == PS) {
5745 // Convert SO1 to GO1's type.
5746 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
5748 const Type *PT = TD->getIntPtrType();
5749 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
5750 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
5754 if (isa<Constant>(SO1) && isa<Constant>(GO1))
5755 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
5757 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
5758 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
5762 // Recycle the GEP we already have if possible.
5763 if (SrcGEPOperands.size() == 2) {
5764 GEP.setOperand(0, SrcGEPOperands[0]);
5765 GEP.setOperand(1, Sum);
5768 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5769 SrcGEPOperands.end()-1);
5770 Indices.push_back(Sum);
5771 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
5773 } else if (isa<Constant>(*GEP.idx_begin()) &&
5774 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
5775 SrcGEPOperands.size() != 1) {
5776 // Otherwise we can do the fold if the first index of the GEP is a zero
5777 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5778 SrcGEPOperands.end());
5779 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
5782 if (!Indices.empty())
5783 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
5785 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
5786 // GEP of global variable. If all of the indices for this GEP are
5787 // constants, we can promote this to a constexpr instead of an instruction.
5789 // Scan for nonconstants...
5790 std::vector<Constant*> Indices;
5791 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
5792 for (; I != E && isa<Constant>(*I); ++I)
5793 Indices.push_back(cast<Constant>(*I));
5795 if (I == E) { // If they are all constants...
5796 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
5798 // Replace all uses of the GEP with the new constexpr...
5799 return ReplaceInstUsesWith(GEP, CE);
5801 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
5802 if (!isa<PointerType>(X->getType())) {
5803 // Not interesting. Source pointer must be a cast from pointer.
5804 } else if (HasZeroPointerIndex) {
5805 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
5806 // into : GEP [10 x ubyte]* X, long 0, ...
5808 // This occurs when the program declares an array extern like "int X[];"
5810 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
5811 const PointerType *XTy = cast<PointerType>(X->getType());
5812 if (const ArrayType *XATy =
5813 dyn_cast<ArrayType>(XTy->getElementType()))
5814 if (const ArrayType *CATy =
5815 dyn_cast<ArrayType>(CPTy->getElementType()))
5816 if (CATy->getElementType() == XATy->getElementType()) {
5817 // At this point, we know that the cast source type is a pointer
5818 // to an array of the same type as the destination pointer
5819 // array. Because the array type is never stepped over (there
5820 // is a leading zero) we can fold the cast into this GEP.
5821 GEP.setOperand(0, X);
5824 } else if (GEP.getNumOperands() == 2) {
5825 // Transform things like:
5826 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
5827 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
5828 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
5829 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
5830 if (isa<ArrayType>(SrcElTy) &&
5831 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
5832 TD->getTypeSize(ResElTy)) {
5833 Value *V = InsertNewInstBefore(
5834 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5835 GEP.getOperand(1), GEP.getName()), GEP);
5836 return new CastInst(V, GEP.getType());
5839 // Transform things like:
5840 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
5841 // (where tmp = 8*tmp2) into:
5842 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
5844 if (isa<ArrayType>(SrcElTy) &&
5845 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
5846 uint64_t ArrayEltSize =
5847 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
5849 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
5850 // allow either a mul, shift, or constant here.
5852 ConstantInt *Scale = 0;
5853 if (ArrayEltSize == 1) {
5854 NewIdx = GEP.getOperand(1);
5855 Scale = ConstantInt::get(NewIdx->getType(), 1);
5856 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
5857 NewIdx = ConstantInt::get(CI->getType(), 1);
5859 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
5860 if (Inst->getOpcode() == Instruction::Shl &&
5861 isa<ConstantInt>(Inst->getOperand(1))) {
5862 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
5863 if (Inst->getType()->isSigned())
5864 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
5866 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
5867 NewIdx = Inst->getOperand(0);
5868 } else if (Inst->getOpcode() == Instruction::Mul &&
5869 isa<ConstantInt>(Inst->getOperand(1))) {
5870 Scale = cast<ConstantInt>(Inst->getOperand(1));
5871 NewIdx = Inst->getOperand(0);
5875 // If the index will be to exactly the right offset with the scale taken
5876 // out, perform the transformation.
5877 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
5878 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
5879 Scale = ConstantSInt::get(C->getType(),
5880 (int64_t)C->getRawValue() /
5881 (int64_t)ArrayEltSize);
5883 Scale = ConstantUInt::get(Scale->getType(),
5884 Scale->getRawValue() / ArrayEltSize);
5885 if (Scale->getRawValue() != 1) {
5886 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
5887 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
5888 NewIdx = InsertNewInstBefore(Sc, GEP);
5891 // Insert the new GEP instruction.
5893 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5894 NewIdx, GEP.getName());
5895 Idx = InsertNewInstBefore(Idx, GEP);
5896 return new CastInst(Idx, GEP.getType());
5905 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
5906 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
5907 if (AI.isArrayAllocation()) // Check C != 1
5908 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
5909 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
5910 AllocationInst *New = 0;
5912 // Create and insert the replacement instruction...
5913 if (isa<MallocInst>(AI))
5914 New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
5916 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
5917 New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
5920 InsertNewInstBefore(New, AI);
5922 // Scan to the end of the allocation instructions, to skip over a block of
5923 // allocas if possible...
5925 BasicBlock::iterator It = New;
5926 while (isa<AllocationInst>(*It)) ++It;
5928 // Now that I is pointing to the first non-allocation-inst in the block,
5929 // insert our getelementptr instruction...
5931 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5932 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5933 New->getName()+".sub", It);
5935 // Now make everything use the getelementptr instead of the original
5937 return ReplaceInstUsesWith(AI, V);
5938 } else if (isa<UndefValue>(AI.getArraySize())) {
5939 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5942 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5943 // Note that we only do this for alloca's, because malloc should allocate and
5944 // return a unique pointer, even for a zero byte allocation.
5945 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5946 TD->getTypeSize(AI.getAllocatedType()) == 0)
5947 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5952 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5953 Value *Op = FI.getOperand(0);
5955 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5956 if (CastInst *CI = dyn_cast<CastInst>(Op))
5957 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5958 FI.setOperand(0, CI->getOperand(0));
5962 // free undef -> unreachable.
5963 if (isa<UndefValue>(Op)) {
5964 // Insert a new store to null because we cannot modify the CFG here.
5965 new StoreInst(ConstantBool::True,
5966 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5967 return EraseInstFromFunction(FI);
5970 // If we have 'free null' delete the instruction. This can happen in stl code
5971 // when lots of inlining happens.
5972 if (isa<ConstantPointerNull>(Op))
5973 return EraseInstFromFunction(FI);
5979 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5980 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5981 User *CI = cast<User>(LI.getOperand(0));
5982 Value *CastOp = CI->getOperand(0);
5984 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5985 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5986 const Type *SrcPTy = SrcTy->getElementType();
5988 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5989 // If the source is an array, the code below will not succeed. Check to
5990 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5992 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5993 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5994 if (ASrcTy->getNumElements() != 0) {
5995 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5996 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5997 SrcTy = cast<PointerType>(CastOp->getType());
5998 SrcPTy = SrcTy->getElementType();
6001 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
6002 // Do not allow turning this into a load of an integer, which is then
6003 // casted to a pointer, this pessimizes pointer analysis a lot.
6004 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
6005 IC.getTargetData().getTypeSize(SrcPTy) ==
6006 IC.getTargetData().getTypeSize(DestPTy)) {
6008 // Okay, we are casting from one integer or pointer type to another of
6009 // the same size. Instead of casting the pointer before the load, cast
6010 // the result of the loaded value.
6011 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
6013 LI.isVolatile()),LI);
6014 // Now cast the result of the load.
6015 return new CastInst(NewLoad, LI.getType());
6022 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
6023 /// from this value cannot trap. If it is not obviously safe to load from the
6024 /// specified pointer, we do a quick local scan of the basic block containing
6025 /// ScanFrom, to determine if the address is already accessed.
6026 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
6027 // If it is an alloca or global variable, it is always safe to load from.
6028 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
6030 // Otherwise, be a little bit agressive by scanning the local block where we
6031 // want to check to see if the pointer is already being loaded or stored
6032 // from/to. If so, the previous load or store would have already trapped,
6033 // so there is no harm doing an extra load (also, CSE will later eliminate
6034 // the load entirely).
6035 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
6040 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
6041 if (LI->getOperand(0) == V) return true;
6042 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
6043 if (SI->getOperand(1) == V) return true;
6049 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
6050 Value *Op = LI.getOperand(0);
6052 // load (cast X) --> cast (load X) iff safe
6053 if (CastInst *CI = dyn_cast<CastInst>(Op))
6054 if (Instruction *Res = InstCombineLoadCast(*this, LI))
6057 // None of the following transforms are legal for volatile loads.
6058 if (LI.isVolatile()) return 0;
6060 if (&LI.getParent()->front() != &LI) {
6061 BasicBlock::iterator BBI = &LI; --BBI;
6062 // If the instruction immediately before this is a store to the same
6063 // address, do a simple form of store->load forwarding.
6064 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
6065 if (SI->getOperand(1) == LI.getOperand(0))
6066 return ReplaceInstUsesWith(LI, SI->getOperand(0));
6067 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
6068 if (LIB->getOperand(0) == LI.getOperand(0))
6069 return ReplaceInstUsesWith(LI, LIB);
6072 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
6073 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
6074 isa<UndefValue>(GEPI->getOperand(0))) {
6075 // Insert a new store to null instruction before the load to indicate
6076 // that this code is not reachable. We do this instead of inserting
6077 // an unreachable instruction directly because we cannot modify the
6079 new StoreInst(UndefValue::get(LI.getType()),
6080 Constant::getNullValue(Op->getType()), &LI);
6081 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
6084 if (Constant *C = dyn_cast<Constant>(Op)) {
6085 // load null/undef -> undef
6086 if ((C->isNullValue() || isa<UndefValue>(C))) {
6087 // Insert a new store to null instruction before the load to indicate that
6088 // this code is not reachable. We do this instead of inserting an
6089 // unreachable instruction directly because we cannot modify the CFG.
6090 new StoreInst(UndefValue::get(LI.getType()),
6091 Constant::getNullValue(Op->getType()), &LI);
6092 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
6095 // Instcombine load (constant global) into the value loaded.
6096 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
6097 if (GV->isConstant() && !GV->isExternal())
6098 return ReplaceInstUsesWith(LI, GV->getInitializer());
6100 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
6101 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
6102 if (CE->getOpcode() == Instruction::GetElementPtr) {
6103 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
6104 if (GV->isConstant() && !GV->isExternal())
6106 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
6107 return ReplaceInstUsesWith(LI, V);
6108 if (CE->getOperand(0)->isNullValue()) {
6109 // Insert a new store to null instruction before the load to indicate
6110 // that this code is not reachable. We do this instead of inserting
6111 // an unreachable instruction directly because we cannot modify the
6113 new StoreInst(UndefValue::get(LI.getType()),
6114 Constant::getNullValue(Op->getType()), &LI);
6115 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
6118 } else if (CE->getOpcode() == Instruction::Cast) {
6119 if (Instruction *Res = InstCombineLoadCast(*this, LI))
6124 if (Op->hasOneUse()) {
6125 // Change select and PHI nodes to select values instead of addresses: this
6126 // helps alias analysis out a lot, allows many others simplifications, and
6127 // exposes redundancy in the code.
6129 // Note that we cannot do the transformation unless we know that the
6130 // introduced loads cannot trap! Something like this is valid as long as
6131 // the condition is always false: load (select bool %C, int* null, int* %G),
6132 // but it would not be valid if we transformed it to load from null
6135 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
6136 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
6137 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
6138 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
6139 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
6140 SI->getOperand(1)->getName()+".val"), LI);
6141 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
6142 SI->getOperand(2)->getName()+".val"), LI);
6143 return new SelectInst(SI->getCondition(), V1, V2);
6146 // load (select (cond, null, P)) -> load P
6147 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
6148 if (C->isNullValue()) {
6149 LI.setOperand(0, SI->getOperand(2));
6153 // load (select (cond, P, null)) -> load P
6154 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
6155 if (C->isNullValue()) {
6156 LI.setOperand(0, SI->getOperand(1));
6160 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
6161 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
6162 bool Safe = PN->getParent() == LI.getParent();
6164 // Scan all of the instructions between the PHI and the load to make
6165 // sure there are no instructions that might possibly alter the value
6166 // loaded from the PHI.
6168 BasicBlock::iterator I = &LI;
6169 for (--I; !isa<PHINode>(I); --I)
6170 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
6176 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
6177 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
6178 PN->getIncomingBlock(i)->getTerminator()))
6183 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
6184 InsertNewInstBefore(NewPN, *PN);
6185 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
6187 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
6188 BasicBlock *BB = PN->getIncomingBlock(i);
6189 Value *&TheLoad = LoadMap[BB];
6191 Value *InVal = PN->getIncomingValue(i);
6192 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
6193 InVal->getName()+".val"),
6194 *BB->getTerminator());
6196 NewPN->addIncoming(TheLoad, BB);
6198 return ReplaceInstUsesWith(LI, NewPN);
6205 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
6207 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
6208 User *CI = cast<User>(SI.getOperand(1));
6209 Value *CastOp = CI->getOperand(0);
6211 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
6212 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
6213 const Type *SrcPTy = SrcTy->getElementType();
6215 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
6216 // If the source is an array, the code below will not succeed. Check to
6217 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
6219 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
6220 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
6221 if (ASrcTy->getNumElements() != 0) {
6222 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
6223 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
6224 SrcTy = cast<PointerType>(CastOp->getType());
6225 SrcPTy = SrcTy->getElementType();
6228 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
6229 IC.getTargetData().getTypeSize(SrcPTy) ==
6230 IC.getTargetData().getTypeSize(DestPTy)) {
6232 // Okay, we are casting from one integer or pointer type to another of
6233 // the same size. Instead of casting the pointer before the store, cast
6234 // the value to be stored.
6236 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
6237 NewCast = ConstantExpr::getCast(C, SrcPTy);
6239 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
6241 SI.getOperand(0)->getName()+".c"), SI);
6243 return new StoreInst(NewCast, CastOp);
6250 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
6251 Value *Val = SI.getOperand(0);
6252 Value *Ptr = SI.getOperand(1);
6254 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
6255 EraseInstFromFunction(SI);
6260 // Do really simple DSE, to catch cases where there are several consequtive
6261 // stores to the same location, separated by a few arithmetic operations. This
6262 // situation often occurs with bitfield accesses.
6263 BasicBlock::iterator BBI = &SI;
6264 for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
6268 if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
6269 // Prev store isn't volatile, and stores to the same location?
6270 if (!PrevSI->isVolatile() && PrevSI->getOperand(1) == SI.getOperand(1)) {
6273 EraseInstFromFunction(*PrevSI);
6279 // Don't skip over loads or things that can modify memory.
6280 if (BBI->mayWriteToMemory() || isa<LoadInst>(BBI))
6285 if (SI.isVolatile()) return 0; // Don't hack volatile stores.
6287 // store X, null -> turns into 'unreachable' in SimplifyCFG
6288 if (isa<ConstantPointerNull>(Ptr)) {
6289 if (!isa<UndefValue>(Val)) {
6290 SI.setOperand(0, UndefValue::get(Val->getType()));
6291 if (Instruction *U = dyn_cast<Instruction>(Val))
6292 WorkList.push_back(U); // Dropped a use.
6295 return 0; // Do not modify these!
6298 // store undef, Ptr -> noop
6299 if (isa<UndefValue>(Val)) {
6300 EraseInstFromFunction(SI);
6305 // If the pointer destination is a cast, see if we can fold the cast into the
6307 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
6308 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
6310 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
6311 if (CE->getOpcode() == Instruction::Cast)
6312 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
6316 // If this store is the last instruction in the basic block, and if the block
6317 // ends with an unconditional branch, try to move it to the successor block.
6319 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
6320 if (BI->isUnconditional()) {
6321 // Check to see if the successor block has exactly two incoming edges. If
6322 // so, see if the other predecessor contains a store to the same location.
6323 // if so, insert a PHI node (if needed) and move the stores down.
6324 BasicBlock *Dest = BI->getSuccessor(0);
6326 pred_iterator PI = pred_begin(Dest);
6327 BasicBlock *Other = 0;
6328 if (*PI != BI->getParent())
6331 if (PI != pred_end(Dest)) {
6332 if (*PI != BI->getParent())
6337 if (++PI != pred_end(Dest))
6340 if (Other) { // If only one other pred...
6341 BBI = Other->getTerminator();
6342 // Make sure this other block ends in an unconditional branch and that
6343 // there is an instruction before the branch.
6344 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
6345 BBI != Other->begin()) {
6347 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
6349 // If this instruction is a store to the same location.
6350 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
6351 // Okay, we know we can perform this transformation. Insert a PHI
6352 // node now if we need it.
6353 Value *MergedVal = OtherStore->getOperand(0);
6354 if (MergedVal != SI.getOperand(0)) {
6355 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
6356 PN->reserveOperandSpace(2);
6357 PN->addIncoming(SI.getOperand(0), SI.getParent());
6358 PN->addIncoming(OtherStore->getOperand(0), Other);
6359 MergedVal = InsertNewInstBefore(PN, Dest->front());
6362 // Advance to a place where it is safe to insert the new store and
6364 BBI = Dest->begin();
6365 while (isa<PHINode>(BBI)) ++BBI;
6366 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
6367 OtherStore->isVolatile()), *BBI);
6369 // Nuke the old stores.
6370 EraseInstFromFunction(SI);
6371 EraseInstFromFunction(*OtherStore);
6383 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
6384 // Change br (not X), label True, label False to: br X, label False, True
6386 BasicBlock *TrueDest;
6387 BasicBlock *FalseDest;
6388 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
6389 !isa<Constant>(X)) {
6390 // Swap Destinations and condition...
6392 BI.setSuccessor(0, FalseDest);
6393 BI.setSuccessor(1, TrueDest);
6397 // Cannonicalize setne -> seteq
6398 Instruction::BinaryOps Op; Value *Y;
6399 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
6400 TrueDest, FalseDest)))
6401 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
6402 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
6403 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
6404 std::string Name = I->getName(); I->setName("");
6405 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
6406 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
6407 // Swap Destinations and condition...
6408 BI.setCondition(NewSCC);
6409 BI.setSuccessor(0, FalseDest);
6410 BI.setSuccessor(1, TrueDest);
6411 removeFromWorkList(I);
6412 I->getParent()->getInstList().erase(I);
6413 WorkList.push_back(cast<Instruction>(NewSCC));
6420 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
6421 Value *Cond = SI.getCondition();
6422 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
6423 if (I->getOpcode() == Instruction::Add)
6424 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
6425 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
6426 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
6427 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
6429 SI.setOperand(0, I->getOperand(0));
6430 WorkList.push_back(I);
6437 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
6438 if (ConstantAggregateZero *C =
6439 dyn_cast<ConstantAggregateZero>(EI.getOperand(0))) {
6440 // If packed val is constant 0, replace extract with scalar 0
6441 const Type *Ty = cast<PackedType>(C->getType())->getElementType();
6442 EI.replaceAllUsesWith(Constant::getNullValue(Ty));
6443 return ReplaceInstUsesWith(EI, Constant::getNullValue(Ty));
6445 if (ConstantPacked *C = dyn_cast<ConstantPacked>(EI.getOperand(0))) {
6446 // If packed val is constant with uniform operands, replace EI
6447 // with that operand
6448 Constant *op0 = cast<Constant>(C->getOperand(0));
6449 for (unsigned i = 1; i < C->getNumOperands(); ++i)
6450 if (C->getOperand(i) != op0) return 0;
6451 return ReplaceInstUsesWith(EI, op0);
6453 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0)))
6454 if (I->hasOneUse()) {
6455 // Push extractelement into predecessor operation if legal and
6456 // profitable to do so
6457 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
6458 if (!isa<Constant>(BO->getOperand(0)) &&
6459 !isa<Constant>(BO->getOperand(1)))
6461 ExtractElementInst *newEI0 =
6462 new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
6464 ExtractElementInst *newEI1 =
6465 new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
6467 InsertNewInstBefore(newEI0, EI);
6468 InsertNewInstBefore(newEI1, EI);
6469 return BinaryOperator::create(BO->getOpcode(), newEI0, newEI1);
6471 switch(I->getOpcode()) {
6472 case Instruction::Load: {
6473 Value *Ptr = InsertCastBefore(I->getOperand(0),
6474 PointerType::get(EI.getType()), EI);
6475 GetElementPtrInst *GEP =
6476 new GetElementPtrInst(Ptr, EI.getOperand(1),
6477 I->getName() + ".gep");
6478 InsertNewInstBefore(GEP, EI);
6479 return new LoadInst(GEP);
6489 void InstCombiner::removeFromWorkList(Instruction *I) {
6490 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
6495 /// TryToSinkInstruction - Try to move the specified instruction from its
6496 /// current block into the beginning of DestBlock, which can only happen if it's
6497 /// safe to move the instruction past all of the instructions between it and the
6498 /// end of its block.
6499 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
6500 assert(I->hasOneUse() && "Invariants didn't hold!");
6502 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
6503 if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
6505 // Do not sink alloca instructions out of the entry block.
6506 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
6509 // We can only sink load instructions if there is nothing between the load and
6510 // the end of block that could change the value.
6511 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
6512 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
6514 if (Scan->mayWriteToMemory())
6518 BasicBlock::iterator InsertPos = DestBlock->begin();
6519 while (isa<PHINode>(InsertPos)) ++InsertPos;
6521 I->moveBefore(InsertPos);
6526 bool InstCombiner::runOnFunction(Function &F) {
6527 bool Changed = false;
6528 TD = &getAnalysis<TargetData>();
6531 // Populate the worklist with the reachable instructions.
6532 std::set<BasicBlock*> Visited;
6533 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
6534 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
6535 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
6536 WorkList.push_back(I);
6538 // Do a quick scan over the function. If we find any blocks that are
6539 // unreachable, remove any instructions inside of them. This prevents
6540 // the instcombine code from having to deal with some bad special cases.
6541 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
6542 if (!Visited.count(BB)) {
6543 Instruction *Term = BB->getTerminator();
6544 while (Term != BB->begin()) { // Remove instrs bottom-up
6545 BasicBlock::iterator I = Term; --I;
6547 DEBUG(std::cerr << "IC: DCE: " << *I);
6550 if (!I->use_empty())
6551 I->replaceAllUsesWith(UndefValue::get(I->getType()));
6552 I->eraseFromParent();
6557 while (!WorkList.empty()) {
6558 Instruction *I = WorkList.back(); // Get an instruction from the worklist
6559 WorkList.pop_back();
6561 // Check to see if we can DCE or ConstantPropagate the instruction...
6562 // Check to see if we can DIE the instruction...
6563 if (isInstructionTriviallyDead(I)) {
6564 // Add operands to the worklist...
6565 if (I->getNumOperands() < 4)
6566 AddUsesToWorkList(*I);
6569 DEBUG(std::cerr << "IC: DCE: " << *I);
6571 I->eraseFromParent();
6572 removeFromWorkList(I);
6576 // Instruction isn't dead, see if we can constant propagate it...
6577 if (Constant *C = ConstantFoldInstruction(I)) {
6578 Value* Ptr = I->getOperand(0);
6579 if (isa<GetElementPtrInst>(I) &&
6580 cast<Constant>(Ptr)->isNullValue() &&
6581 !isa<ConstantPointerNull>(C) &&
6582 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
6583 // If this is a constant expr gep that is effectively computing an
6584 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
6585 bool isFoldableGEP = true;
6586 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
6587 if (!isa<ConstantInt>(I->getOperand(i)))
6588 isFoldableGEP = false;
6589 if (isFoldableGEP) {
6590 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
6591 std::vector<Value*>(I->op_begin()+1, I->op_end()));
6592 C = ConstantUInt::get(Type::ULongTy, Offset);
6593 C = ConstantExpr::getCast(C, TD->getIntPtrType());
6594 C = ConstantExpr::getCast(C, I->getType());
6598 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
6600 // Add operands to the worklist...
6601 AddUsesToWorkList(*I);
6602 ReplaceInstUsesWith(*I, C);
6605 I->getParent()->getInstList().erase(I);
6606 removeFromWorkList(I);
6610 // See if we can trivially sink this instruction to a successor basic block.
6611 if (I->hasOneUse()) {
6612 BasicBlock *BB = I->getParent();
6613 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
6614 if (UserParent != BB) {
6615 bool UserIsSuccessor = false;
6616 // See if the user is one of our successors.
6617 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
6618 if (*SI == UserParent) {
6619 UserIsSuccessor = true;
6623 // If the user is one of our immediate successors, and if that successor
6624 // only has us as a predecessors (we'd have to split the critical edge
6625 // otherwise), we can keep going.
6626 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
6627 next(pred_begin(UserParent)) == pred_end(UserParent))
6628 // Okay, the CFG is simple enough, try to sink this instruction.
6629 Changed |= TryToSinkInstruction(I, UserParent);
6633 // Now that we have an instruction, try combining it to simplify it...
6634 if (Instruction *Result = visit(*I)) {
6636 // Should we replace the old instruction with a new one?
6638 DEBUG(std::cerr << "IC: Old = " << *I
6639 << " New = " << *Result);
6641 // Everything uses the new instruction now.
6642 I->replaceAllUsesWith(Result);
6644 // Push the new instruction and any users onto the worklist.
6645 WorkList.push_back(Result);
6646 AddUsersToWorkList(*Result);
6648 // Move the name to the new instruction first...
6649 std::string OldName = I->getName(); I->setName("");
6650 Result->setName(OldName);
6652 // Insert the new instruction into the basic block...
6653 BasicBlock *InstParent = I->getParent();
6654 BasicBlock::iterator InsertPos = I;
6656 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
6657 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
6660 InstParent->getInstList().insert(InsertPos, Result);
6662 // Make sure that we reprocess all operands now that we reduced their
6664 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
6665 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
6666 WorkList.push_back(OpI);
6668 // Instructions can end up on the worklist more than once. Make sure
6669 // we do not process an instruction that has been deleted.
6670 removeFromWorkList(I);
6672 // Erase the old instruction.
6673 InstParent->getInstList().erase(I);
6675 DEBUG(std::cerr << "IC: MOD = " << *I);
6677 // If the instruction was modified, it's possible that it is now dead.
6678 // if so, remove it.
6679 if (isInstructionTriviallyDead(I)) {
6680 // Make sure we process all operands now that we are reducing their
6682 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
6683 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
6684 WorkList.push_back(OpI);
6686 // Instructions may end up in the worklist more than once. Erase all
6687 // occurrences of this instruction.
6688 removeFromWorkList(I);
6689 I->eraseFromParent();
6691 WorkList.push_back(Result);
6692 AddUsersToWorkList(*Result);
6702 FunctionPass *llvm::createInstructionCombiningPass() {
6703 return new InstCombiner();