1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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
12 // algebraic simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All cmp instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "InstCombine.h"
39 #include "llvm/IntrinsicInst.h"
40 #include "llvm/LLVMContext.h"
41 #include "llvm/DerivedTypes.h"
42 #include "llvm/GlobalVariable.h"
43 #include "llvm/Operator.h"
44 #include "llvm/Analysis/ConstantFolding.h"
45 #include "llvm/Analysis/InstructionSimplify.h"
46 #include "llvm/Analysis/MemoryBuiltins.h"
47 #include "llvm/Target/TargetData.h"
48 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
49 #include "llvm/Transforms/Utils/Local.h"
50 #include "llvm/Support/CallSite.h"
51 #include "llvm/Support/Debug.h"
52 #include "llvm/Support/ErrorHandling.h"
53 #include "llvm/Support/GetElementPtrTypeIterator.h"
54 #include "llvm/Support/MathExtras.h"
55 #include "llvm/Support/PatternMatch.h"
56 #include "llvm/ADT/SmallPtrSet.h"
57 #include "llvm/ADT/Statistic.h"
58 #include "llvm/ADT/STLExtras.h"
62 using namespace llvm::PatternMatch;
64 STATISTIC(NumCombined , "Number of insts combined");
65 STATISTIC(NumConstProp, "Number of constant folds");
66 STATISTIC(NumDeadInst , "Number of dead inst eliminated");
67 STATISTIC(NumDeadStore, "Number of dead stores eliminated");
68 STATISTIC(NumSunkInst , "Number of instructions sunk");
71 char InstCombiner::ID = 0;
72 static RegisterPass<InstCombiner>
73 X("instcombine", "Combine redundant instructions");
75 void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
76 AU.addPreservedID(LCSSAID);
81 // isOnlyUse - Return true if this instruction will be deleted if we stop using
83 static bool isOnlyUse(Value *V) {
84 return V->hasOneUse() || isa<Constant>(V);
87 // getPromotedType - Return the specified type promoted as it would be to pass
88 // though a va_arg area...
89 static const Type *getPromotedType(const Type *Ty) {
90 if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
91 if (ITy->getBitWidth() < 32)
92 return Type::getInt32Ty(Ty->getContext());
97 /// ShouldChangeType - Return true if it is desirable to convert a computation
98 /// from 'From' to 'To'. We don't want to convert from a legal to an illegal
99 /// type for example, or from a smaller to a larger illegal type.
100 static bool ShouldChangeType(const Type *From, const Type *To,
101 const TargetData *TD) {
102 assert(isa<IntegerType>(From) && isa<IntegerType>(To));
104 // If we don't have TD, we don't know if the source/dest are legal.
105 if (!TD) return false;
107 unsigned FromWidth = From->getPrimitiveSizeInBits();
108 unsigned ToWidth = To->getPrimitiveSizeInBits();
109 bool FromLegal = TD->isLegalInteger(FromWidth);
110 bool ToLegal = TD->isLegalInteger(ToWidth);
112 // If this is a legal integer from type, and the result would be an illegal
113 // type, don't do the transformation.
114 if (FromLegal && !ToLegal)
117 // Otherwise, if both are illegal, do not increase the size of the result. We
118 // do allow things like i160 -> i64, but not i64 -> i160.
119 if (!FromLegal && !ToLegal && ToWidth > FromWidth)
125 /// getBitCastOperand - If the specified operand is a CastInst, a constant
126 /// expression bitcast, or a GetElementPtrInst with all zero indices, return the
127 /// operand value, otherwise return null.
128 static Value *getBitCastOperand(Value *V) {
129 if (Operator *O = dyn_cast<Operator>(V)) {
130 if (O->getOpcode() == Instruction::BitCast)
131 return O->getOperand(0);
132 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
133 if (GEP->hasAllZeroIndices())
134 return GEP->getPointerOperand();
139 /// This function is a wrapper around CastInst::isEliminableCastPair. It
140 /// simply extracts arguments and returns what that function returns.
141 static Instruction::CastOps
142 isEliminableCastPair(
143 const CastInst *CI, ///< The first cast instruction
144 unsigned opcode, ///< The opcode of the second cast instruction
145 const Type *DstTy, ///< The target type for the second cast instruction
146 TargetData *TD ///< The target data for pointer size
149 const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
150 const Type *MidTy = CI->getType(); // B from above
152 // Get the opcodes of the two Cast instructions
153 Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
154 Instruction::CastOps secondOp = Instruction::CastOps(opcode);
156 unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
158 TD ? TD->getIntPtrType(CI->getContext()) : 0);
160 // We don't want to form an inttoptr or ptrtoint that converts to an integer
161 // type that differs from the pointer size.
162 if ((Res == Instruction::IntToPtr &&
163 (!TD || SrcTy != TD->getIntPtrType(CI->getContext()))) ||
164 (Res == Instruction::PtrToInt &&
165 (!TD || DstTy != TD->getIntPtrType(CI->getContext()))))
168 return Instruction::CastOps(Res);
171 /// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
172 /// in any code being generated. It does not require codegen if V is simple
173 /// enough or if the cast can be folded into other casts.
174 static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V,
175 const Type *Ty, TargetData *TD) {
176 if (V->getType() == Ty || isa<Constant>(V)) return false;
178 // If this is another cast that can be eliminated, it isn't codegen either.
179 if (const CastInst *CI = dyn_cast<CastInst>(V))
180 if (isEliminableCastPair(CI, opcode, Ty, TD))
185 // SimplifyCommutative - This performs a few simplifications for commutative
188 // 1. Order operands such that they are listed from right (least complex) to
189 // left (most complex). This puts constants before unary operators before
192 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
193 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
195 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
196 bool Changed = false;
197 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
198 Changed = !I.swapOperands();
200 if (!I.isAssociative()) return Changed;
201 Instruction::BinaryOps Opcode = I.getOpcode();
202 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
203 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
204 if (isa<Constant>(I.getOperand(1))) {
205 Constant *Folded = ConstantExpr::get(I.getOpcode(),
206 cast<Constant>(I.getOperand(1)),
207 cast<Constant>(Op->getOperand(1)));
208 I.setOperand(0, Op->getOperand(0));
209 I.setOperand(1, Folded);
211 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
212 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
213 isOnlyUse(Op) && isOnlyUse(Op1)) {
214 Constant *C1 = cast<Constant>(Op->getOperand(1));
215 Constant *C2 = cast<Constant>(Op1->getOperand(1));
217 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
218 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
219 Instruction *New = BinaryOperator::Create(Opcode, Op->getOperand(0),
223 I.setOperand(0, New);
224 I.setOperand(1, Folded);
231 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
232 // if the LHS is a constant zero (which is the 'negate' form).
234 Value *InstCombiner::dyn_castNegVal(Value *V) const {
235 if (BinaryOperator::isNeg(V))
236 return BinaryOperator::getNegArgument(V);
238 // Constants can be considered to be negated values if they can be folded.
239 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
240 return ConstantExpr::getNeg(C);
242 if (ConstantVector *C = dyn_cast<ConstantVector>(V))
243 if (C->getType()->getElementType()->isInteger())
244 return ConstantExpr::getNeg(C);
249 // dyn_castFNegVal - Given a 'fsub' instruction, return the RHS of the
250 // instruction if the LHS is a constant negative zero (which is the 'negate'
253 static inline Value *dyn_castFNegVal(Value *V) {
254 if (BinaryOperator::isFNeg(V))
255 return BinaryOperator::getFNegArgument(V);
257 // Constants can be considered to be negated values if they can be folded.
258 if (ConstantFP *C = dyn_cast<ConstantFP>(V))
259 return ConstantExpr::getFNeg(C);
261 if (ConstantVector *C = dyn_cast<ConstantVector>(V))
262 if (C->getType()->getElementType()->isFloatingPoint())
263 return ConstantExpr::getFNeg(C);
268 /// MatchSelectPattern - Pattern match integer [SU]MIN, [SU]MAX, and ABS idioms,
269 /// returning the kind and providing the out parameter results if we
270 /// successfully match.
271 static SelectPatternFlavor
272 MatchSelectPattern(Value *V, Value *&LHS, Value *&RHS) {
273 SelectInst *SI = dyn_cast<SelectInst>(V);
274 if (SI == 0) return SPF_UNKNOWN;
276 ICmpInst *ICI = dyn_cast<ICmpInst>(SI->getCondition());
277 if (ICI == 0) return SPF_UNKNOWN;
279 LHS = ICI->getOperand(0);
280 RHS = ICI->getOperand(1);
282 // (icmp X, Y) ? X : Y
283 if (SI->getTrueValue() == ICI->getOperand(0) &&
284 SI->getFalseValue() == ICI->getOperand(1)) {
285 switch (ICI->getPredicate()) {
286 default: return SPF_UNKNOWN; // Equality.
287 case ICmpInst::ICMP_UGT:
288 case ICmpInst::ICMP_UGE: return SPF_UMAX;
289 case ICmpInst::ICMP_SGT:
290 case ICmpInst::ICMP_SGE: return SPF_SMAX;
291 case ICmpInst::ICMP_ULT:
292 case ICmpInst::ICMP_ULE: return SPF_UMIN;
293 case ICmpInst::ICMP_SLT:
294 case ICmpInst::ICMP_SLE: return SPF_SMIN;
298 // (icmp X, Y) ? Y : X
299 if (SI->getTrueValue() == ICI->getOperand(1) &&
300 SI->getFalseValue() == ICI->getOperand(0)) {
301 switch (ICI->getPredicate()) {
302 default: return SPF_UNKNOWN; // Equality.
303 case ICmpInst::ICMP_UGT:
304 case ICmpInst::ICMP_UGE: return SPF_UMIN;
305 case ICmpInst::ICMP_SGT:
306 case ICmpInst::ICMP_SGE: return SPF_SMIN;
307 case ICmpInst::ICMP_ULT:
308 case ICmpInst::ICMP_ULE: return SPF_UMAX;
309 case ICmpInst::ICMP_SLT:
310 case ICmpInst::ICMP_SLE: return SPF_SMAX;
314 // TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5)
319 /// isFreeToInvert - Return true if the specified value is free to invert (apply
320 /// ~ to). This happens in cases where the ~ can be eliminated.
321 static inline bool isFreeToInvert(Value *V) {
323 if (BinaryOperator::isNot(V))
326 // Constants can be considered to be not'ed values.
327 if (isa<ConstantInt>(V))
330 // Compares can be inverted if they have a single use.
331 if (CmpInst *CI = dyn_cast<CmpInst>(V))
332 return CI->hasOneUse();
337 static inline Value *dyn_castNotVal(Value *V) {
338 // If this is not(not(x)) don't return that this is a not: we want the two
339 // not's to be folded first.
340 if (BinaryOperator::isNot(V)) {
341 Value *Operand = BinaryOperator::getNotArgument(V);
342 if (!isFreeToInvert(Operand))
346 // Constants can be considered to be not'ed values...
347 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
348 return ConstantInt::get(C->getType(), ~C->getValue());
354 // dyn_castFoldableMul - If this value is a multiply that can be folded into
355 // other computations (because it has a constant operand), return the
356 // non-constant operand of the multiply, and set CST to point to the multiplier.
357 // Otherwise, return null.
359 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
360 if (V->hasOneUse() && V->getType()->isInteger())
361 if (Instruction *I = dyn_cast<Instruction>(V)) {
362 if (I->getOpcode() == Instruction::Mul)
363 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
364 return I->getOperand(0);
365 if (I->getOpcode() == Instruction::Shl)
366 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
367 // The multiplier is really 1 << CST.
368 uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
369 uint32_t CSTVal = CST->getLimitedValue(BitWidth);
370 CST = ConstantInt::get(V->getType()->getContext(),
371 APInt(BitWidth, 1).shl(CSTVal));
372 return I->getOperand(0);
378 /// AddOne - Add one to a ConstantInt
379 static Constant *AddOne(Constant *C) {
380 return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
382 /// SubOne - Subtract one from a ConstantInt
383 static Constant *SubOne(ConstantInt *C) {
384 return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
386 /// MultiplyOverflows - True if the multiply can not be expressed in an int
388 static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
389 uint32_t W = C1->getBitWidth();
390 APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
399 APInt MulExt = LHSExt * RHSExt;
402 return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
404 APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
405 APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
406 return MulExt.slt(Min) || MulExt.sgt(Max);
411 /// AssociativeOpt - Perform an optimization on an associative operator. This
412 /// function is designed to check a chain of associative operators for a
413 /// potential to apply a certain optimization. Since the optimization may be
414 /// applicable if the expression was reassociated, this checks the chain, then
415 /// reassociates the expression as necessary to expose the optimization
416 /// opportunity. This makes use of a special Functor, which must define
417 /// 'shouldApply' and 'apply' methods.
419 template<typename Functor>
420 static Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
421 unsigned Opcode = Root.getOpcode();
422 Value *LHS = Root.getOperand(0);
424 // Quick check, see if the immediate LHS matches...
425 if (F.shouldApply(LHS))
426 return F.apply(Root);
428 // Otherwise, if the LHS is not of the same opcode as the root, return.
429 Instruction *LHSI = dyn_cast<Instruction>(LHS);
430 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
431 // Should we apply this transform to the RHS?
432 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
434 // If not to the RHS, check to see if we should apply to the LHS...
435 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
436 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
440 // If the functor wants to apply the optimization to the RHS of LHSI,
441 // reassociate the expression from ((? op A) op B) to (? op (A op B))
443 // Now all of the instructions are in the current basic block, go ahead
444 // and perform the reassociation.
445 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
447 // First move the selected RHS to the LHS of the root...
448 Root.setOperand(0, LHSI->getOperand(1));
450 // Make what used to be the LHS of the root be the user of the root...
451 Value *ExtraOperand = TmpLHSI->getOperand(1);
452 if (&Root == TmpLHSI) {
453 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
456 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
457 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
458 BasicBlock::iterator ARI = &Root; ++ARI;
459 TmpLHSI->moveBefore(ARI); // Move TmpLHSI to after Root
462 // Now propagate the ExtraOperand down the chain of instructions until we
464 while (TmpLHSI != LHSI) {
465 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
466 // Move the instruction to immediately before the chain we are
467 // constructing to avoid breaking dominance properties.
468 NextLHSI->moveBefore(ARI);
471 Value *NextOp = NextLHSI->getOperand(1);
472 NextLHSI->setOperand(1, ExtraOperand);
474 ExtraOperand = NextOp;
477 // Now that the instructions are reassociated, have the functor perform
478 // the transformation...
479 return F.apply(Root);
482 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
489 // AddRHS - Implements: X + X --> X << 1
492 explicit AddRHS(Value *rhs) : RHS(rhs) {}
493 bool shouldApply(Value *LHS) const { return LHS == RHS; }
494 Instruction *apply(BinaryOperator &Add) const {
495 return BinaryOperator::CreateShl(Add.getOperand(0),
496 ConstantInt::get(Add.getType(), 1));
500 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
502 struct AddMaskingAnd {
504 explicit AddMaskingAnd(Constant *c) : C2(c) {}
505 bool shouldApply(Value *LHS) const {
507 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
508 ConstantExpr::getAnd(C1, C2)->isNullValue();
510 Instruction *apply(BinaryOperator &Add) const {
511 return BinaryOperator::CreateOr(Add.getOperand(0), Add.getOperand(1));
517 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
519 if (CastInst *CI = dyn_cast<CastInst>(&I))
520 return IC->Builder->CreateCast(CI->getOpcode(), SO, I.getType());
522 // Figure out if the constant is the left or the right argument.
523 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
524 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
526 if (Constant *SOC = dyn_cast<Constant>(SO)) {
528 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
529 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
532 Value *Op0 = SO, *Op1 = ConstOperand;
536 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
537 return IC->Builder->CreateBinOp(BO->getOpcode(), Op0, Op1,
538 SO->getName()+".op");
539 if (ICmpInst *CI = dyn_cast<ICmpInst>(&I))
540 return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
541 SO->getName()+".cmp");
542 if (FCmpInst *CI = dyn_cast<FCmpInst>(&I))
543 return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
544 SO->getName()+".cmp");
545 llvm_unreachable("Unknown binary instruction type!");
548 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
549 // constant as the other operand, try to fold the binary operator into the
550 // select arguments. This also works for Cast instructions, which obviously do
551 // not have a second operand.
552 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
554 // Don't modify shared select instructions
555 if (!SI->hasOneUse()) return 0;
556 Value *TV = SI->getOperand(1);
557 Value *FV = SI->getOperand(2);
559 if (isa<Constant>(TV) || isa<Constant>(FV)) {
560 // Bool selects with constant operands can be folded to logical ops.
561 if (SI->getType() == Type::getInt1Ty(SI->getContext())) return 0;
563 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
564 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
566 return SelectInst::Create(SI->getCondition(), SelectTrueVal,
573 /// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
574 /// has a PHI node as operand #0, see if we can fold the instruction into the
575 /// PHI (which is only possible if all operands to the PHI are constants).
577 /// If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
578 /// that would normally be unprofitable because they strongly encourage jump
580 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
581 bool AllowAggressive) {
582 AllowAggressive = false;
583 PHINode *PN = cast<PHINode>(I.getOperand(0));
584 unsigned NumPHIValues = PN->getNumIncomingValues();
585 if (NumPHIValues == 0 ||
586 // We normally only transform phis with a single use, unless we're trying
587 // hard to make jump threading happen.
588 (!PN->hasOneUse() && !AllowAggressive))
592 // Check to see if all of the operands of the PHI are simple constants
593 // (constantint/constantfp/undef). If there is one non-constant value,
594 // remember the BB it is in. If there is more than one or if *it* is a PHI,
595 // bail out. We don't do arbitrary constant expressions here because moving
596 // their computation can be expensive without a cost model.
597 BasicBlock *NonConstBB = 0;
598 for (unsigned i = 0; i != NumPHIValues; ++i)
599 if (!isa<Constant>(PN->getIncomingValue(i)) ||
600 isa<ConstantExpr>(PN->getIncomingValue(i))) {
601 if (NonConstBB) return 0; // More than one non-const value.
602 if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi.
603 NonConstBB = PN->getIncomingBlock(i);
605 // If the incoming non-constant value is in I's block, we have an infinite
607 if (NonConstBB == I.getParent())
611 // If there is exactly one non-constant value, we can insert a copy of the
612 // operation in that block. However, if this is a critical edge, we would be
613 // inserting the computation one some other paths (e.g. inside a loop). Only
614 // do this if the pred block is unconditionally branching into the phi block.
615 if (NonConstBB != 0 && !AllowAggressive) {
616 BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
617 if (!BI || !BI->isUnconditional()) return 0;
620 // Okay, we can do the transformation: create the new PHI node.
621 PHINode *NewPN = PHINode::Create(I.getType(), "");
622 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
623 InsertNewInstBefore(NewPN, *PN);
626 // Next, add all of the operands to the PHI.
627 if (SelectInst *SI = dyn_cast<SelectInst>(&I)) {
628 // We only currently try to fold the condition of a select when it is a phi,
629 // not the true/false values.
630 Value *TrueV = SI->getTrueValue();
631 Value *FalseV = SI->getFalseValue();
632 BasicBlock *PhiTransBB = PN->getParent();
633 for (unsigned i = 0; i != NumPHIValues; ++i) {
634 BasicBlock *ThisBB = PN->getIncomingBlock(i);
635 Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
636 Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
638 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
639 InV = InC->isNullValue() ? FalseVInPred : TrueVInPred;
641 assert(PN->getIncomingBlock(i) == NonConstBB);
642 InV = SelectInst::Create(PN->getIncomingValue(i), TrueVInPred,
644 "phitmp", NonConstBB->getTerminator());
645 Worklist.Add(cast<Instruction>(InV));
647 NewPN->addIncoming(InV, ThisBB);
649 } else if (I.getNumOperands() == 2) {
650 Constant *C = cast<Constant>(I.getOperand(1));
651 for (unsigned i = 0; i != NumPHIValues; ++i) {
653 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
654 if (CmpInst *CI = dyn_cast<CmpInst>(&I))
655 InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
657 InV = ConstantExpr::get(I.getOpcode(), InC, C);
659 assert(PN->getIncomingBlock(i) == NonConstBB);
660 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
661 InV = BinaryOperator::Create(BO->getOpcode(),
662 PN->getIncomingValue(i), C, "phitmp",
663 NonConstBB->getTerminator());
664 else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
665 InV = CmpInst::Create(CI->getOpcode(),
667 PN->getIncomingValue(i), C, "phitmp",
668 NonConstBB->getTerminator());
670 llvm_unreachable("Unknown binop!");
672 Worklist.Add(cast<Instruction>(InV));
674 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
677 CastInst *CI = cast<CastInst>(&I);
678 const Type *RetTy = CI->getType();
679 for (unsigned i = 0; i != NumPHIValues; ++i) {
681 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
682 InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
684 assert(PN->getIncomingBlock(i) == NonConstBB);
685 InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i),
686 I.getType(), "phitmp",
687 NonConstBB->getTerminator());
688 Worklist.Add(cast<Instruction>(InV));
690 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
693 return ReplaceInstUsesWith(I, NewPN);
697 /// WillNotOverflowSignedAdd - Return true if we can prove that:
698 /// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS))
699 /// This basically requires proving that the add in the original type would not
700 /// overflow to change the sign bit or have a carry out.
701 bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
702 // There are different heuristics we can use for this. Here are some simple
705 // Add has the property that adding any two 2's complement numbers can only
706 // have one carry bit which can change a sign. As such, if LHS and RHS each
707 // have at least two sign bits, we know that the addition of the two values
708 // will sign extend fine.
709 if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
713 // If one of the operands only has one non-zero bit, and if the other operand
714 // has a known-zero bit in a more significant place than it (not including the
715 // sign bit) the ripple may go up to and fill the zero, but won't change the
716 // sign. For example, (X & ~4) + 1.
724 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
725 bool Changed = SimplifyCommutative(I);
726 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
728 if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
729 I.hasNoUnsignedWrap(), TD))
730 return ReplaceInstUsesWith(I, V);
733 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
734 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
735 // X + (signbit) --> X ^ signbit
736 const APInt& Val = CI->getValue();
737 uint32_t BitWidth = Val.getBitWidth();
738 if (Val == APInt::getSignBit(BitWidth))
739 return BinaryOperator::CreateXor(LHS, RHS);
741 // See if SimplifyDemandedBits can simplify this. This handles stuff like
742 // (X & 254)+1 -> (X&254)|1
743 if (SimplifyDemandedInstructionBits(I))
746 // zext(bool) + C -> bool ? C + 1 : C
747 if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
748 if (ZI->getSrcTy() == Type::getInt1Ty(I.getContext()))
749 return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
752 if (isa<PHINode>(LHS))
753 if (Instruction *NV = FoldOpIntoPhi(I))
756 ConstantInt *XorRHS = 0;
758 if (isa<ConstantInt>(RHSC) &&
759 match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
760 uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
761 const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
763 uint32_t Size = TySizeBits / 2;
764 APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
765 APInt CFF80Val(-C0080Val);
767 if (TySizeBits > Size) {
768 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
769 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
770 if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
771 (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
772 // This is a sign extend if the top bits are known zero.
773 if (!MaskedValueIsZero(XorLHS,
774 APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
775 Size = 0; // Not a sign ext, but can't be any others either.
780 C0080Val = APIntOps::lshr(C0080Val, Size);
781 CFF80Val = APIntOps::ashr(CFF80Val, Size);
784 // FIXME: This shouldn't be necessary. When the backends can handle types
785 // with funny bit widths then this switch statement should be removed. It
786 // is just here to get the size of the "middle" type back up to something
787 // that the back ends can handle.
788 const Type *MiddleType = 0;
793 case 8: MiddleType = IntegerType::get(I.getContext(), Size); break;
796 Value *NewTrunc = Builder->CreateTrunc(XorLHS, MiddleType, "sext");
797 return new SExtInst(NewTrunc, I.getType(), I.getName());
802 if (I.getType() == Type::getInt1Ty(I.getContext()))
803 return BinaryOperator::CreateXor(LHS, RHS);
806 if (I.getType()->isInteger()) {
807 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS)))
810 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
811 if (RHSI->getOpcode() == Instruction::Sub)
812 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
813 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
815 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
816 if (LHSI->getOpcode() == Instruction::Sub)
817 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
818 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
823 // -A + -B --> -(A + B)
824 if (Value *LHSV = dyn_castNegVal(LHS)) {
825 if (LHS->getType()->isIntOrIntVector()) {
826 if (Value *RHSV = dyn_castNegVal(RHS)) {
827 Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
828 return BinaryOperator::CreateNeg(NewAdd);
832 return BinaryOperator::CreateSub(RHS, LHSV);
836 if (!isa<Constant>(RHS))
837 if (Value *V = dyn_castNegVal(RHS))
838 return BinaryOperator::CreateSub(LHS, V);
842 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
843 if (X == RHS) // X*C + X --> X * (C+1)
844 return BinaryOperator::CreateMul(RHS, AddOne(C2));
846 // X*C1 + X*C2 --> X * (C1+C2)
848 if (X == dyn_castFoldableMul(RHS, C1))
849 return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
852 // X + X*C --> X * (C+1)
853 if (dyn_castFoldableMul(RHS, C2) == LHS)
854 return BinaryOperator::CreateMul(LHS, AddOne(C2));
856 // X + ~X --> -1 since ~X = -X-1
857 if (dyn_castNotVal(LHS) == RHS ||
858 dyn_castNotVal(RHS) == LHS)
859 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
862 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
863 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
864 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
867 // A+B --> A|B iff A and B have no bits set in common.
868 if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
869 APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
870 APInt LHSKnownOne(IT->getBitWidth(), 0);
871 APInt LHSKnownZero(IT->getBitWidth(), 0);
872 ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
873 if (LHSKnownZero != 0) {
874 APInt RHSKnownOne(IT->getBitWidth(), 0);
875 APInt RHSKnownZero(IT->getBitWidth(), 0);
876 ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
878 // No bits in common -> bitwise or.
879 if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
880 return BinaryOperator::CreateOr(LHS, RHS);
884 // W*X + Y*Z --> W * (X+Z) iff W == Y
885 if (I.getType()->isIntOrIntVector()) {
886 Value *W, *X, *Y, *Z;
887 if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
888 match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
901 Value *NewAdd = Builder->CreateAdd(X, Z, LHS->getName());
902 return BinaryOperator::CreateMul(W, NewAdd);
907 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
909 if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
910 return BinaryOperator::CreateSub(SubOne(CRHS), X);
912 // (X & FF00) + xx00 -> (X+xx00) & FF00
913 if (LHS->hasOneUse() &&
914 match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
915 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
917 // See if all bits from the first bit set in the Add RHS up are included
918 // in the mask. First, get the rightmost bit.
919 const APInt& AddRHSV = CRHS->getValue();
921 // Form a mask of all bits from the lowest bit added through the top.
922 APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
924 // See if the and mask includes all of these bits.
925 APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
927 if (AddRHSHighBits == AddRHSHighBitsAnd) {
928 // Okay, the xform is safe. Insert the new add pronto.
929 Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
930 return BinaryOperator::CreateAnd(NewAdd, C2);
935 // Try to fold constant add into select arguments.
936 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
937 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
941 // add (select X 0 (sub n A)) A --> select X A n
943 SelectInst *SI = dyn_cast<SelectInst>(LHS);
946 SI = dyn_cast<SelectInst>(RHS);
949 if (SI && SI->hasOneUse()) {
950 Value *TV = SI->getTrueValue();
951 Value *FV = SI->getFalseValue();
954 // Can we fold the add into the argument of the select?
955 // We check both true and false select arguments for a matching subtract.
956 if (match(FV, m_Zero()) &&
957 match(TV, m_Sub(m_Value(N), m_Specific(A))))
958 // Fold the add into the true select value.
959 return SelectInst::Create(SI->getCondition(), N, A);
960 if (match(TV, m_Zero()) &&
961 match(FV, m_Sub(m_Value(N), m_Specific(A))))
962 // Fold the add into the false select value.
963 return SelectInst::Create(SI->getCondition(), A, N);
967 // Check for (add (sext x), y), see if we can merge this into an
968 // integer add followed by a sext.
969 if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
970 // (add (sext x), cst) --> (sext (add x, cst'))
971 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
973 ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
974 if (LHSConv->hasOneUse() &&
975 ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
976 WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
977 // Insert the new, smaller add.
978 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
980 return new SExtInst(NewAdd, I.getType());
984 // (add (sext x), (sext y)) --> (sext (add int x, y))
985 if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
986 // Only do this if x/y have the same type, if at last one of them has a
987 // single use (so we don't increase the number of sexts), and if the
988 // integer add will not overflow.
989 if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
990 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
991 WillNotOverflowSignedAdd(LHSConv->getOperand(0),
992 RHSConv->getOperand(0))) {
993 // Insert the new integer add.
994 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
995 RHSConv->getOperand(0), "addconv");
996 return new SExtInst(NewAdd, I.getType());
1001 return Changed ? &I : 0;
1004 Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
1005 bool Changed = SimplifyCommutative(I);
1006 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1008 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1010 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1011 if (CFP->isExactlyValue(ConstantFP::getNegativeZero
1012 (I.getType())->getValueAPF()))
1013 return ReplaceInstUsesWith(I, LHS);
1016 if (isa<PHINode>(LHS))
1017 if (Instruction *NV = FoldOpIntoPhi(I))
1022 // -A + -B --> -(A + B)
1023 if (Value *LHSV = dyn_castFNegVal(LHS))
1024 return BinaryOperator::CreateFSub(RHS, LHSV);
1027 if (!isa<Constant>(RHS))
1028 if (Value *V = dyn_castFNegVal(RHS))
1029 return BinaryOperator::CreateFSub(LHS, V);
1031 // Check for X+0.0. Simplify it to X if we know X is not -0.0.
1032 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
1033 if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
1034 return ReplaceInstUsesWith(I, LHS);
1036 // Check for (add double (sitofp x), y), see if we can merge this into an
1037 // integer add followed by a promotion.
1038 if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
1039 // (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
1040 // ... if the constant fits in the integer value. This is useful for things
1041 // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
1042 // requires a constant pool load, and generally allows the add to be better
1044 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
1046 ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
1047 if (LHSConv->hasOneUse() &&
1048 ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
1049 WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
1050 // Insert the new integer add.
1051 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
1053 return new SIToFPInst(NewAdd, I.getType());
1057 // (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
1058 if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
1059 // Only do this if x/y have the same type, if at last one of them has a
1060 // single use (so we don't increase the number of int->fp conversions),
1061 // and if the integer add will not overflow.
1062 if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
1063 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
1064 WillNotOverflowSignedAdd(LHSConv->getOperand(0),
1065 RHSConv->getOperand(0))) {
1066 // Insert the new integer add.
1067 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
1068 RHSConv->getOperand(0),"addconv");
1069 return new SIToFPInst(NewAdd, I.getType());
1074 return Changed ? &I : 0;
1078 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
1079 /// code necessary to compute the offset from the base pointer (without adding
1080 /// in the base pointer). Return the result as a signed integer of intptr size.
1081 Value *InstCombiner::EmitGEPOffset(User *GEP) {
1082 TargetData &TD = *getTargetData();
1083 gep_type_iterator GTI = gep_type_begin(GEP);
1084 const Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
1085 Value *Result = Constant::getNullValue(IntPtrTy);
1087 // Build a mask for high order bits.
1088 unsigned IntPtrWidth = TD.getPointerSizeInBits();
1089 uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
1091 for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
1094 uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
1095 if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
1096 if (OpC->isZero()) continue;
1098 // Handle a struct index, which adds its field offset to the pointer.
1099 if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
1100 Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
1102 Result = Builder->CreateAdd(Result,
1103 ConstantInt::get(IntPtrTy, Size),
1104 GEP->getName()+".offs");
1108 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
1110 ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
1111 Scale = ConstantExpr::getMul(OC, Scale);
1112 // Emit an add instruction.
1113 Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
1116 // Convert to correct type.
1117 if (Op->getType() != IntPtrTy)
1118 Op = Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
1120 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
1121 // We'll let instcombine(mul) convert this to a shl if possible.
1122 Op = Builder->CreateMul(Op, Scale, GEP->getName()+".idx");
1125 // Emit an add instruction.
1126 Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
1134 /// Optimize pointer differences into the same array into a size. Consider:
1135 /// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
1136 /// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
1138 Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
1140 assert(TD && "Must have target data info for this");
1142 // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
1145 GetElementPtrInst *GEP = 0;
1146 ConstantExpr *CstGEP = 0;
1148 // TODO: Could also optimize &A[i] - &A[j] -> "i-j", and "&A.foo[i] - &A.foo".
1149 // For now we require one side to be the base pointer "A" or a constant
1150 // expression derived from it.
1151 if (GetElementPtrInst *LHSGEP = dyn_cast<GetElementPtrInst>(LHS)) {
1153 if (LHSGEP->getOperand(0) == RHS) {
1156 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(RHS)) {
1157 // (gep X, ...) - (ce_gep X, ...)
1158 if (CE->getOpcode() == Instruction::GetElementPtr &&
1159 LHSGEP->getOperand(0) == CE->getOperand(0)) {
1167 if (GetElementPtrInst *RHSGEP = dyn_cast<GetElementPtrInst>(RHS)) {
1169 if (RHSGEP->getOperand(0) == LHS) {
1172 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(LHS)) {
1173 // (ce_gep X, ...) - (gep X, ...)
1174 if (CE->getOpcode() == Instruction::GetElementPtr &&
1175 RHSGEP->getOperand(0) == CE->getOperand(0)) {
1186 // Emit the offset of the GEP and an intptr_t.
1187 Value *Result = EmitGEPOffset(GEP);
1189 // If we had a constant expression GEP on the other side offsetting the
1190 // pointer, subtract it from the offset we have.
1192 Value *CstOffset = EmitGEPOffset(CstGEP);
1193 Result = Builder->CreateSub(Result, CstOffset);
1197 // If we have p - gep(p, ...) then we have to negate the result.
1199 Result = Builder->CreateNeg(Result, "diff.neg");
1201 return Builder->CreateIntCast(Result, Ty, true);
1205 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
1206 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1208 if (Op0 == Op1) // sub X, X -> 0
1209 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1211 // If this is a 'B = x-(-A)', change to B = x+A. This preserves NSW/NUW.
1212 if (Value *V = dyn_castNegVal(Op1)) {
1213 BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V);
1214 Res->setHasNoSignedWrap(I.hasNoSignedWrap());
1215 Res->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
1219 if (isa<UndefValue>(Op0))
1220 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
1221 if (isa<UndefValue>(Op1))
1222 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
1223 if (I.getType() == Type::getInt1Ty(I.getContext()))
1224 return BinaryOperator::CreateXor(Op0, Op1);
1226 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
1227 // Replace (-1 - A) with (~A).
1228 if (C->isAllOnesValue())
1229 return BinaryOperator::CreateNot(Op1);
1231 // C - ~X == X + (1+C)
1233 if (match(Op1, m_Not(m_Value(X))))
1234 return BinaryOperator::CreateAdd(X, AddOne(C));
1236 // -(X >>u 31) -> (X >>s 31)
1237 // -(X >>s 31) -> (X >>u 31)
1239 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) {
1240 if (SI->getOpcode() == Instruction::LShr) {
1241 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
1242 // Check to see if we are shifting out everything but the sign bit.
1243 if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
1244 SI->getType()->getPrimitiveSizeInBits()-1) {
1245 // Ok, the transformation is safe. Insert AShr.
1246 return BinaryOperator::Create(Instruction::AShr,
1247 SI->getOperand(0), CU, SI->getName());
1250 } else if (SI->getOpcode() == Instruction::AShr) {
1251 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
1252 // Check to see if we are shifting out everything but the sign bit.
1253 if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
1254 SI->getType()->getPrimitiveSizeInBits()-1) {
1255 // Ok, the transformation is safe. Insert LShr.
1256 return BinaryOperator::CreateLShr(
1257 SI->getOperand(0), CU, SI->getName());
1264 // Try to fold constant sub into select arguments.
1265 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1266 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1269 // C - zext(bool) -> bool ? C - 1 : C
1270 if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1))
1271 if (ZI->getSrcTy() == Type::getInt1Ty(I.getContext()))
1272 return SelectInst::Create(ZI->getOperand(0), SubOne(C), C);
1275 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
1276 if (Op1I->getOpcode() == Instruction::Add) {
1277 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
1278 return BinaryOperator::CreateNeg(Op1I->getOperand(1),
1280 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
1281 return BinaryOperator::CreateNeg(Op1I->getOperand(0),
1283 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
1284 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
1285 // C1-(X+C2) --> (C1-C2)-X
1286 return BinaryOperator::CreateSub(
1287 ConstantExpr::getSub(CI1, CI2), Op1I->getOperand(0));
1291 if (Op1I->hasOneUse()) {
1292 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
1293 // is not used by anyone else...
1295 if (Op1I->getOpcode() == Instruction::Sub) {
1296 // Swap the two operands of the subexpr...
1297 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
1298 Op1I->setOperand(0, IIOp1);
1299 Op1I->setOperand(1, IIOp0);
1301 // Create the new top level add instruction...
1302 return BinaryOperator::CreateAdd(Op0, Op1);
1305 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
1307 if (Op1I->getOpcode() == Instruction::And &&
1308 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
1309 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
1311 Value *NewNot = Builder->CreateNot(OtherOp, "B.not");
1312 return BinaryOperator::CreateAnd(Op0, NewNot);
1315 // 0 - (X sdiv C) -> (X sdiv -C)
1316 if (Op1I->getOpcode() == Instruction::SDiv)
1317 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
1319 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
1320 return BinaryOperator::CreateSDiv(Op1I->getOperand(0),
1321 ConstantExpr::getNeg(DivRHS));
1323 // X - X*C --> X * (1-C)
1324 ConstantInt *C2 = 0;
1325 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
1327 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
1329 return BinaryOperator::CreateMul(Op0, CP1);
1334 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1335 if (Op0I->getOpcode() == Instruction::Add) {
1336 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
1337 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1338 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
1339 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1340 } else if (Op0I->getOpcode() == Instruction::Sub) {
1341 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
1342 return BinaryOperator::CreateNeg(Op0I->getOperand(1),
1348 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1349 if (X == Op1) // X*C - X --> X * (C-1)
1350 return BinaryOperator::CreateMul(Op1, SubOne(C1));
1352 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1353 if (X == dyn_castFoldableMul(Op1, C2))
1354 return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
1357 // Optimize pointer differences into the same array into a size. Consider:
1358 // &A[10] - &A[0]: we should compile this to "10".
1360 Value *LHSOp, *RHSOp;
1361 if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
1362 match(Op1, m_PtrToInt(m_Value(RHSOp))))
1363 if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
1364 return ReplaceInstUsesWith(I, Res);
1366 // trunc(p)-trunc(q) -> trunc(p-q)
1367 if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
1368 match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
1369 if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
1370 return ReplaceInstUsesWith(I, Res);
1376 Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
1377 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1379 // If this is a 'B = x-(-A)', change to B = x+A...
1380 if (Value *V = dyn_castFNegVal(Op1))
1381 return BinaryOperator::CreateFAdd(Op0, V);
1383 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
1384 if (Op1I->getOpcode() == Instruction::FAdd) {
1385 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
1386 return BinaryOperator::CreateFNeg(Op1I->getOperand(1),
1388 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
1389 return BinaryOperator::CreateFNeg(Op1I->getOperand(0),
1397 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
1398 bool Changed = SimplifyCommutative(I);
1399 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1401 if (isa<UndefValue>(Op1)) // undef * X -> 0
1402 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1404 // Simplify mul instructions with a constant RHS.
1405 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
1406 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1C)) {
1408 // ((X << C1)*C2) == (X * (C2 << C1))
1409 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
1410 if (SI->getOpcode() == Instruction::Shl)
1411 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
1412 return BinaryOperator::CreateMul(SI->getOperand(0),
1413 ConstantExpr::getShl(CI, ShOp));
1416 return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0
1417 if (CI->equalsInt(1)) // X * 1 == X
1418 return ReplaceInstUsesWith(I, Op0);
1419 if (CI->isAllOnesValue()) // X * -1 == 0 - X
1420 return BinaryOperator::CreateNeg(Op0, I.getName());
1422 const APInt& Val = cast<ConstantInt>(CI)->getValue();
1423 if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
1424 return BinaryOperator::CreateShl(Op0,
1425 ConstantInt::get(Op0->getType(), Val.logBase2()));
1427 } else if (isa<VectorType>(Op1C->getType())) {
1428 if (Op1C->isNullValue())
1429 return ReplaceInstUsesWith(I, Op1C);
1431 if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
1432 if (Op1V->isAllOnesValue()) // X * -1 == 0 - X
1433 return BinaryOperator::CreateNeg(Op0, I.getName());
1435 // As above, vector X*splat(1.0) -> X in all defined cases.
1436 if (Constant *Splat = Op1V->getSplatValue()) {
1437 if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat))
1438 if (CI->equalsInt(1))
1439 return ReplaceInstUsesWith(I, Op0);
1444 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
1445 if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
1446 isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1C)) {
1447 // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
1448 Value *Add = Builder->CreateMul(Op0I->getOperand(0), Op1C, "tmp");
1449 Value *C1C2 = Builder->CreateMul(Op1C, Op0I->getOperand(1));
1450 return BinaryOperator::CreateAdd(Add, C1C2);
1454 // Try to fold constant mul into select arguments.
1455 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1456 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1459 if (isa<PHINode>(Op0))
1460 if (Instruction *NV = FoldOpIntoPhi(I))
1464 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
1465 if (Value *Op1v = dyn_castNegVal(Op1))
1466 return BinaryOperator::CreateMul(Op0v, Op1v);
1468 // (X / Y) * Y = X - (X % Y)
1469 // (X / Y) * -Y = (X % Y) - X
1472 BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
1474 (BO->getOpcode() != Instruction::UDiv &&
1475 BO->getOpcode() != Instruction::SDiv)) {
1477 BO = dyn_cast<BinaryOperator>(Op1);
1479 Value *Neg = dyn_castNegVal(Op1C);
1480 if (BO && BO->hasOneUse() &&
1481 (BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) &&
1482 (BO->getOpcode() == Instruction::UDiv ||
1483 BO->getOpcode() == Instruction::SDiv)) {
1484 Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
1486 // If the division is exact, X % Y is zero.
1487 if (SDivOperator *SDiv = dyn_cast<SDivOperator>(BO))
1488 if (SDiv->isExact()) {
1490 return ReplaceInstUsesWith(I, Op0BO);
1491 return BinaryOperator::CreateNeg(Op0BO);
1495 if (BO->getOpcode() == Instruction::UDiv)
1496 Rem = Builder->CreateURem(Op0BO, Op1BO);
1498 Rem = Builder->CreateSRem(Op0BO, Op1BO);
1502 return BinaryOperator::CreateSub(Op0BO, Rem);
1503 return BinaryOperator::CreateSub(Rem, Op0BO);
1507 /// i1 mul -> i1 and.
1508 if (I.getType() == Type::getInt1Ty(I.getContext()))
1509 return BinaryOperator::CreateAnd(Op0, Op1);
1511 // X*(1 << Y) --> X << Y
1512 // (1 << Y)*X --> X << Y
1515 if (match(Op0, m_Shl(m_One(), m_Value(Y))))
1516 return BinaryOperator::CreateShl(Op1, Y);
1517 if (match(Op1, m_Shl(m_One(), m_Value(Y))))
1518 return BinaryOperator::CreateShl(Op0, Y);
1521 // If one of the operands of the multiply is a cast from a boolean value, then
1522 // we know the bool is either zero or one, so this is a 'masking' multiply.
1523 // X * Y (where Y is 0 or 1) -> X & (0-Y)
1524 if (!isa<VectorType>(I.getType())) {
1525 // -2 is "-1 << 1" so it is all bits set except the low one.
1526 APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
1528 Value *BoolCast = 0, *OtherOp = 0;
1529 if (MaskedValueIsZero(Op0, Negative2))
1530 BoolCast = Op0, OtherOp = Op1;
1531 else if (MaskedValueIsZero(Op1, Negative2))
1532 BoolCast = Op1, OtherOp = Op0;
1535 Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()),
1537 return BinaryOperator::CreateAnd(V, OtherOp);
1541 return Changed ? &I : 0;
1544 Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
1545 bool Changed = SimplifyCommutative(I);
1546 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1548 // Simplify mul instructions with a constant RHS...
1549 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
1550 if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1C)) {
1551 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
1552 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
1553 if (Op1F->isExactlyValue(1.0))
1554 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
1555 } else if (isa<VectorType>(Op1C->getType())) {
1556 if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
1557 // As above, vector X*splat(1.0) -> X in all defined cases.
1558 if (Constant *Splat = Op1V->getSplatValue()) {
1559 if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
1560 if (F->isExactlyValue(1.0))
1561 return ReplaceInstUsesWith(I, Op0);
1566 // Try to fold constant mul into select arguments.
1567 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1568 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1571 if (isa<PHINode>(Op0))
1572 if (Instruction *NV = FoldOpIntoPhi(I))
1576 if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y
1577 if (Value *Op1v = dyn_castFNegVal(Op1))
1578 return BinaryOperator::CreateFMul(Op0v, Op1v);
1580 return Changed ? &I : 0;
1583 /// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
1585 bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
1586 SelectInst *SI = cast<SelectInst>(I.getOperand(1));
1588 // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
1589 int NonNullOperand = -1;
1590 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
1591 if (ST->isNullValue())
1593 // div/rem X, (Cond ? Y : 0) -> div/rem X, Y
1594 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
1595 if (ST->isNullValue())
1598 if (NonNullOperand == -1)
1601 Value *SelectCond = SI->getOperand(0);
1603 // Change the div/rem to use 'Y' instead of the select.
1604 I.setOperand(1, SI->getOperand(NonNullOperand));
1606 // Okay, we know we replace the operand of the div/rem with 'Y' with no
1607 // problem. However, the select, or the condition of the select may have
1608 // multiple uses. Based on our knowledge that the operand must be non-zero,
1609 // propagate the known value for the select into other uses of it, and
1610 // propagate a known value of the condition into its other users.
1612 // If the select and condition only have a single use, don't bother with this,
1614 if (SI->use_empty() && SelectCond->hasOneUse())
1617 // Scan the current block backward, looking for other uses of SI.
1618 BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
1620 while (BBI != BBFront) {
1622 // If we found a call to a function, we can't assume it will return, so
1623 // information from below it cannot be propagated above it.
1624 if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
1627 // Replace uses of the select or its condition with the known values.
1628 for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
1631 *I = SI->getOperand(NonNullOperand);
1633 } else if (*I == SelectCond) {
1634 *I = NonNullOperand == 1 ? ConstantInt::getTrue(BBI->getContext()) :
1635 ConstantInt::getFalse(BBI->getContext());
1640 // If we past the instruction, quit looking for it.
1643 if (&*BBI == SelectCond)
1646 // If we ran out of things to eliminate, break out of the loop.
1647 if (SelectCond == 0 && SI == 0)
1655 /// This function implements the transforms on div instructions that work
1656 /// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
1657 /// used by the visitors to those instructions.
1658 /// @brief Transforms common to all three div instructions
1659 Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
1660 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1662 // undef / X -> 0 for integer.
1663 // undef / X -> undef for FP (the undef could be a snan).
1664 if (isa<UndefValue>(Op0)) {
1665 if (Op0->getType()->isFPOrFPVector())
1666 return ReplaceInstUsesWith(I, Op0);
1667 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1670 // X / undef -> undef
1671 if (isa<UndefValue>(Op1))
1672 return ReplaceInstUsesWith(I, Op1);
1677 /// This function implements the transforms common to both integer division
1678 /// instructions (udiv and sdiv). It is called by the visitors to those integer
1679 /// division instructions.
1680 /// @brief Common integer divide transforms
1681 Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
1682 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1684 // (sdiv X, X) --> 1 (udiv X, X) --> 1
1686 if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) {
1687 Constant *CI = ConstantInt::get(Ty->getElementType(), 1);
1688 std::vector<Constant*> Elts(Ty->getNumElements(), CI);
1689 return ReplaceInstUsesWith(I, ConstantVector::get(Elts));
1692 Constant *CI = ConstantInt::get(I.getType(), 1);
1693 return ReplaceInstUsesWith(I, CI);
1696 if (Instruction *Common = commonDivTransforms(I))
1699 // Handle cases involving: [su]div X, (select Cond, Y, Z)
1700 // This does not apply for fdiv.
1701 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
1704 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1706 if (RHS->equalsInt(1))
1707 return ReplaceInstUsesWith(I, Op0);
1709 // (X / C1) / C2 -> X / (C1*C2)
1710 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1711 if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
1712 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1713 if (MultiplyOverflows(RHS, LHSRHS,
1714 I.getOpcode()==Instruction::SDiv))
1715 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1717 return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
1718 ConstantExpr::getMul(RHS, LHSRHS));
1721 if (!RHS->isZero()) { // avoid X udiv 0
1722 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1723 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1725 if (isa<PHINode>(Op0))
1726 if (Instruction *NV = FoldOpIntoPhi(I))
1731 // 0 / X == 0, we don't need to preserve faults!
1732 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1733 if (LHS->equalsInt(0))
1734 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1736 // It can't be division by zero, hence it must be division by one.
1737 if (I.getType() == Type::getInt1Ty(I.getContext()))
1738 return ReplaceInstUsesWith(I, Op0);
1740 if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
1741 if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue()))
1744 return ReplaceInstUsesWith(I, Op0);
1750 Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
1751 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1753 // Handle the integer div common cases
1754 if (Instruction *Common = commonIDivTransforms(I))
1757 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
1758 // X udiv C^2 -> X >> C
1759 // Check to see if this is an unsigned division with an exact power of 2,
1760 // if so, convert to a right shift.
1761 if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
1762 return BinaryOperator::CreateLShr(Op0,
1763 ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
1765 // X udiv C, where C >= signbit
1766 if (C->getValue().isNegative()) {
1767 Value *IC = Builder->CreateICmpULT( Op0, C);
1768 return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
1769 ConstantInt::get(I.getType(), 1));
1773 // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
1774 if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
1775 if (RHSI->getOpcode() == Instruction::Shl &&
1776 isa<ConstantInt>(RHSI->getOperand(0))) {
1777 const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
1778 if (C1.isPowerOf2()) {
1779 Value *N = RHSI->getOperand(1);
1780 const Type *NTy = N->getType();
1781 if (uint32_t C2 = C1.logBase2())
1782 N = Builder->CreateAdd(N, ConstantInt::get(NTy, C2), "tmp");
1783 return BinaryOperator::CreateLShr(Op0, N);
1788 // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
1789 // where C1&C2 are powers of two.
1790 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1791 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
1792 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
1793 const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
1794 if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
1795 // Compute the shift amounts
1796 uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
1797 // Construct the "on true" case of the select
1798 Constant *TC = ConstantInt::get(Op0->getType(), TSA);
1799 Value *TSI = Builder->CreateLShr(Op0, TC, SI->getName()+".t");
1801 // Construct the "on false" case of the select
1802 Constant *FC = ConstantInt::get(Op0->getType(), FSA);
1803 Value *FSI = Builder->CreateLShr(Op0, FC, SI->getName()+".f");
1805 // construct the select instruction and return it.
1806 return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName());
1812 Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
1813 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1815 // Handle the integer div common cases
1816 if (Instruction *Common = commonIDivTransforms(I))
1819 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1821 if (RHS->isAllOnesValue())
1822 return BinaryOperator::CreateNeg(Op0);
1824 // sdiv X, C --> ashr X, log2(C)
1825 if (cast<SDivOperator>(&I)->isExact() &&
1826 RHS->getValue().isNonNegative() &&
1827 RHS->getValue().isPowerOf2()) {
1828 Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
1829 RHS->getValue().exactLogBase2());
1830 return BinaryOperator::CreateAShr(Op0, ShAmt, I.getName());
1833 // -X/C --> X/-C provided the negation doesn't overflow.
1834 if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
1835 if (isa<Constant>(Sub->getOperand(0)) &&
1836 cast<Constant>(Sub->getOperand(0))->isNullValue() &&
1837 Sub->hasNoSignedWrap())
1838 return BinaryOperator::CreateSDiv(Sub->getOperand(1),
1839 ConstantExpr::getNeg(RHS));
1842 // If the sign bits of both operands are zero (i.e. we can prove they are
1843 // unsigned inputs), turn this into a udiv.
1844 if (I.getType()->isInteger()) {
1845 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
1846 if (MaskedValueIsZero(Op0, Mask)) {
1847 if (MaskedValueIsZero(Op1, Mask)) {
1848 // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
1849 return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
1851 ConstantInt *ShiftedInt;
1852 if (match(Op1, m_Shl(m_ConstantInt(ShiftedInt), m_Value())) &&
1853 ShiftedInt->getValue().isPowerOf2()) {
1854 // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
1855 // Safe because the only negative value (1 << Y) can take on is
1856 // INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have
1857 // the sign bit set.
1858 return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
1866 Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
1867 return commonDivTransforms(I);
1870 /// This function implements the transforms on rem instructions that work
1871 /// regardless of the kind of rem instruction it is (urem, srem, or frem). It
1872 /// is used by the visitors to those instructions.
1873 /// @brief Transforms common to all three rem instructions
1874 Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
1875 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1877 if (isa<UndefValue>(Op0)) { // undef % X -> 0
1878 if (I.getType()->isFPOrFPVector())
1879 return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
1880 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1882 if (isa<UndefValue>(Op1))
1883 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1885 // Handle cases involving: rem X, (select Cond, Y, Z)
1886 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
1892 /// This function implements the transforms common to both integer remainder
1893 /// instructions (urem and srem). It is called by the visitors to those integer
1894 /// remainder instructions.
1895 /// @brief Common integer remainder transforms
1896 Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
1897 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1899 if (Instruction *common = commonRemTransforms(I))
1902 // 0 % X == 0 for integer, we don't need to preserve faults!
1903 if (Constant *LHS = dyn_cast<Constant>(Op0))
1904 if (LHS->isNullValue())
1905 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1907 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1908 // X % 0 == undef, we don't need to preserve faults!
1909 if (RHS->equalsInt(0))
1910 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
1912 if (RHS->equalsInt(1)) // X % 1 == 0
1913 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1915 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
1916 if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
1917 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1919 } else if (isa<PHINode>(Op0I)) {
1920 if (Instruction *NV = FoldOpIntoPhi(I))
1924 // See if we can fold away this rem instruction.
1925 if (SimplifyDemandedInstructionBits(I))
1933 Instruction *InstCombiner::visitURem(BinaryOperator &I) {
1934 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1936 if (Instruction *common = commonIRemTransforms(I))
1939 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1940 // X urem C^2 -> X and C
1941 // Check to see if this is an unsigned remainder with an exact power of 2,
1942 // if so, convert to a bitwise and.
1943 if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
1944 if (C->getValue().isPowerOf2())
1945 return BinaryOperator::CreateAnd(Op0, SubOne(C));
1948 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
1949 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
1950 if (RHSI->getOpcode() == Instruction::Shl &&
1951 isa<ConstantInt>(RHSI->getOperand(0))) {
1952 if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
1953 Constant *N1 = Constant::getAllOnesValue(I.getType());
1954 Value *Add = Builder->CreateAdd(RHSI, N1, "tmp");
1955 return BinaryOperator::CreateAnd(Op0, Add);
1960 // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
1961 // where C1&C2 are powers of two.
1962 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
1963 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
1964 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
1965 // STO == 0 and SFO == 0 handled above.
1966 if ((STO->getValue().isPowerOf2()) &&
1967 (SFO->getValue().isPowerOf2())) {
1968 Value *TrueAnd = Builder->CreateAnd(Op0, SubOne(STO),
1969 SI->getName()+".t");
1970 Value *FalseAnd = Builder->CreateAnd(Op0, SubOne(SFO),
1971 SI->getName()+".f");
1972 return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd);
1980 Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
1981 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1983 // Handle the integer rem common cases
1984 if (Instruction *Common = commonIRemTransforms(I))
1987 if (Value *RHSNeg = dyn_castNegVal(Op1))
1988 if (!isa<Constant>(RHSNeg) ||
1989 (isa<ConstantInt>(RHSNeg) &&
1990 cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
1992 Worklist.AddValue(I.getOperand(1));
1993 I.setOperand(1, RHSNeg);
1997 // If the sign bits of both operands are zero (i.e. we can prove they are
1998 // unsigned inputs), turn this into a urem.
1999 if (I.getType()->isInteger()) {
2000 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
2001 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
2002 // X srem Y -> X urem Y, iff X and Y don't have sign bit set
2003 return BinaryOperator::CreateURem(Op0, Op1, I.getName());
2007 // If it's a constant vector, flip any negative values positive.
2008 if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
2009 unsigned VWidth = RHSV->getNumOperands();
2011 bool hasNegative = false;
2012 for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
2013 if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
2014 if (RHS->getValue().isNegative())
2018 std::vector<Constant *> Elts(VWidth);
2019 for (unsigned i = 0; i != VWidth; ++i) {
2020 if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
2021 if (RHS->getValue().isNegative())
2022 Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
2028 Constant *NewRHSV = ConstantVector::get(Elts);
2029 if (NewRHSV != RHSV) {
2030 Worklist.AddValue(I.getOperand(1));
2031 I.setOperand(1, NewRHSV);
2040 Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
2041 return commonRemTransforms(I);
2044 // isOneBitSet - Return true if there is exactly one bit set in the specified
2046 static bool isOneBitSet(const ConstantInt *CI) {
2047 return CI->getValue().isPowerOf2();
2050 /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
2051 /// are carefully arranged to allow folding of expressions such as:
2053 /// (A < B) | (A > B) --> (A != B)
2055 /// Note that this is only valid if the first and second predicates have the
2056 /// same sign. Is illegal to do: (A u< B) | (A s> B)
2058 /// Three bits are used to represent the condition, as follows:
2063 /// <=> Value Definition
2064 /// 000 0 Always false
2071 /// 111 7 Always true
2073 static unsigned getICmpCode(const ICmpInst *ICI) {
2074 switch (ICI->getPredicate()) {
2076 case ICmpInst::ICMP_UGT: return 1; // 001
2077 case ICmpInst::ICMP_SGT: return 1; // 001
2078 case ICmpInst::ICMP_EQ: return 2; // 010
2079 case ICmpInst::ICMP_UGE: return 3; // 011
2080 case ICmpInst::ICMP_SGE: return 3; // 011
2081 case ICmpInst::ICMP_ULT: return 4; // 100
2082 case ICmpInst::ICMP_SLT: return 4; // 100
2083 case ICmpInst::ICMP_NE: return 5; // 101
2084 case ICmpInst::ICMP_ULE: return 6; // 110
2085 case ICmpInst::ICMP_SLE: return 6; // 110
2088 llvm_unreachable("Invalid ICmp predicate!");
2093 /// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
2094 /// predicate into a three bit mask. It also returns whether it is an ordered
2095 /// predicate by reference.
2096 static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
2099 case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000
2100 case FCmpInst::FCMP_UNO: return 0; // 000
2101 case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001
2102 case FCmpInst::FCMP_UGT: return 1; // 001
2103 case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010
2104 case FCmpInst::FCMP_UEQ: return 2; // 010
2105 case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011
2106 case FCmpInst::FCMP_UGE: return 3; // 011
2107 case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100
2108 case FCmpInst::FCMP_ULT: return 4; // 100
2109 case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101
2110 case FCmpInst::FCMP_UNE: return 5; // 101
2111 case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110
2112 case FCmpInst::FCMP_ULE: return 6; // 110
2115 // Not expecting FCMP_FALSE and FCMP_TRUE;
2116 llvm_unreachable("Unexpected FCmp predicate!");
2121 /// getICmpValue - This is the complement of getICmpCode, which turns an
2122 /// opcode and two operands into either a constant true or false, or a brand
2123 /// new ICmp instruction. The sign is passed in to determine which kind
2124 /// of predicate to use in the new icmp instruction.
2125 static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS) {
2127 default: llvm_unreachable("Illegal ICmp code!");
2128 case 0: return ConstantInt::getFalse(LHS->getContext());
2131 return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
2133 return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
2134 case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
2137 return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
2139 return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
2142 return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
2144 return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
2145 case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
2148 return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
2150 return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
2151 case 7: return ConstantInt::getTrue(LHS->getContext());
2155 /// getFCmpValue - This is the complement of getFCmpCode, which turns an
2156 /// opcode and two operands into either a FCmp instruction. isordered is passed
2157 /// in to determine which kind of predicate to use in the new fcmp instruction.
2158 static Value *getFCmpValue(bool isordered, unsigned code,
2159 Value *LHS, Value *RHS) {
2161 default: llvm_unreachable("Illegal FCmp code!");
2164 return new FCmpInst(FCmpInst::FCMP_ORD, LHS, RHS);
2166 return new FCmpInst(FCmpInst::FCMP_UNO, LHS, RHS);
2169 return new FCmpInst(FCmpInst::FCMP_OGT, LHS, RHS);
2171 return new FCmpInst(FCmpInst::FCMP_UGT, LHS, RHS);
2174 return new FCmpInst(FCmpInst::FCMP_OEQ, LHS, RHS);
2176 return new FCmpInst(FCmpInst::FCMP_UEQ, LHS, RHS);
2179 return new FCmpInst(FCmpInst::FCMP_OGE, LHS, RHS);
2181 return new FCmpInst(FCmpInst::FCMP_UGE, LHS, RHS);
2184 return new FCmpInst(FCmpInst::FCMP_OLT, LHS, RHS);
2186 return new FCmpInst(FCmpInst::FCMP_ULT, LHS, RHS);
2189 return new FCmpInst(FCmpInst::FCMP_ONE, LHS, RHS);
2191 return new FCmpInst(FCmpInst::FCMP_UNE, LHS, RHS);
2194 return new FCmpInst(FCmpInst::FCMP_OLE, LHS, RHS);
2196 return new FCmpInst(FCmpInst::FCMP_ULE, LHS, RHS);
2197 case 7: return ConstantInt::getTrue(LHS->getContext());
2201 /// PredicatesFoldable - Return true if both predicates match sign or if at
2202 /// least one of them is an equality comparison (which is signless).
2203 static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
2204 return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) ||
2205 (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
2206 (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
2210 // FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
2211 struct FoldICmpLogical {
2214 ICmpInst::Predicate pred;
2215 FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
2216 : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
2217 pred(ICI->getPredicate()) {}
2218 bool shouldApply(Value *V) const {
2219 if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
2220 if (PredicatesFoldable(pred, ICI->getPredicate()))
2221 return ((ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS) ||
2222 (ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS));
2225 Instruction *apply(Instruction &Log) const {
2226 ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
2227 if (ICI->getOperand(0) != LHS) {
2228 assert(ICI->getOperand(1) == LHS);
2229 ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
2232 ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
2233 unsigned LHSCode = getICmpCode(ICI);
2234 unsigned RHSCode = getICmpCode(RHSICI);
2236 switch (Log.getOpcode()) {
2237 case Instruction::And: Code = LHSCode & RHSCode; break;
2238 case Instruction::Or: Code = LHSCode | RHSCode; break;
2239 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
2240 default: llvm_unreachable("Illegal logical opcode!"); return 0;
2243 bool isSigned = RHSICI->isSigned() || ICI->isSigned();
2244 Value *RV = getICmpValue(isSigned, Code, LHS, RHS);
2245 if (Instruction *I = dyn_cast<Instruction>(RV))
2247 // Otherwise, it's a constant boolean value...
2248 return IC.ReplaceInstUsesWith(Log, RV);
2251 } // end anonymous namespace
2253 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
2254 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
2255 // guaranteed to be a binary operator.
2256 Instruction *InstCombiner::OptAndOp(Instruction *Op,
2258 ConstantInt *AndRHS,
2259 BinaryOperator &TheAnd) {
2260 Value *X = Op->getOperand(0);
2261 Constant *Together = 0;
2263 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
2265 switch (Op->getOpcode()) {
2266 case Instruction::Xor:
2267 if (Op->hasOneUse()) {
2268 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
2269 Value *And = Builder->CreateAnd(X, AndRHS);
2271 return BinaryOperator::CreateXor(And, Together);
2274 case Instruction::Or:
2275 if (Together == AndRHS) // (X | C) & C --> C
2276 return ReplaceInstUsesWith(TheAnd, AndRHS);
2278 if (Op->hasOneUse() && Together != OpRHS) {
2279 // (X | C1) & C2 --> (X | (C1&C2)) & C2
2280 Value *Or = Builder->CreateOr(X, Together);
2282 return BinaryOperator::CreateAnd(Or, AndRHS);
2285 case Instruction::Add:
2286 if (Op->hasOneUse()) {
2287 // Adding a one to a single bit bit-field should be turned into an XOR
2288 // of the bit. First thing to check is to see if this AND is with a
2289 // single bit constant.
2290 const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
2292 // If there is only one bit set...
2293 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
2294 // Ok, at this point, we know that we are masking the result of the
2295 // ADD down to exactly one bit. If the constant we are adding has
2296 // no bits set below this bit, then we can eliminate the ADD.
2297 const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
2299 // Check to see if any bits below the one bit set in AndRHSV are set.
2300 if ((AddRHS & (AndRHSV-1)) == 0) {
2301 // If not, the only thing that can effect the output of the AND is
2302 // the bit specified by AndRHSV. If that bit is set, the effect of
2303 // the XOR is to toggle the bit. If it is clear, then the ADD has
2305 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
2306 TheAnd.setOperand(0, X);
2309 // Pull the XOR out of the AND.
2310 Value *NewAnd = Builder->CreateAnd(X, AndRHS);
2311 NewAnd->takeName(Op);
2312 return BinaryOperator::CreateXor(NewAnd, AndRHS);
2319 case Instruction::Shl: {
2320 // We know that the AND will not produce any of the bits shifted in, so if
2321 // the anded constant includes them, clear them now!
2323 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
2324 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
2325 APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
2326 ConstantInt *CI = ConstantInt::get(AndRHS->getContext(),
2327 AndRHS->getValue() & ShlMask);
2329 if (CI->getValue() == ShlMask) {
2330 // Masking out bits that the shift already masks
2331 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
2332 } else if (CI != AndRHS) { // Reducing bits set in and.
2333 TheAnd.setOperand(1, CI);
2338 case Instruction::LShr: {
2339 // We know that the AND will not produce any of the bits shifted in, so if
2340 // the anded constant includes them, clear them now! This only applies to
2341 // unsigned shifts, because a signed shr may bring in set bits!
2343 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
2344 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
2345 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
2346 ConstantInt *CI = ConstantInt::get(Op->getContext(),
2347 AndRHS->getValue() & ShrMask);
2349 if (CI->getValue() == ShrMask) {
2350 // Masking out bits that the shift already masks.
2351 return ReplaceInstUsesWith(TheAnd, Op);
2352 } else if (CI != AndRHS) {
2353 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
2358 case Instruction::AShr:
2360 // See if this is shifting in some sign extension, then masking it out
2362 if (Op->hasOneUse()) {
2363 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
2364 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
2365 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
2366 Constant *C = ConstantInt::get(Op->getContext(),
2367 AndRHS->getValue() & ShrMask);
2368 if (C == AndRHS) { // Masking out bits shifted in.
2369 // (Val ashr C1) & C2 -> (Val lshr C1) & C2
2370 // Make the argument unsigned.
2371 Value *ShVal = Op->getOperand(0);
2372 ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName());
2373 return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
2382 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
2383 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
2384 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
2385 /// whether to treat the V, Lo and HI as signed or not. IB is the location to
2386 /// insert new instructions.
2387 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
2388 bool isSigned, bool Inside,
2390 assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
2391 ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
2392 "Lo is not <= Hi in range emission code!");
2395 if (Lo == Hi) // Trivially false.
2396 return new ICmpInst(ICmpInst::ICMP_NE, V, V);
2398 // V >= Min && V < Hi --> V < Hi
2399 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
2400 ICmpInst::Predicate pred = (isSigned ?
2401 ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
2402 return new ICmpInst(pred, V, Hi);
2405 // Emit V-Lo <u Hi-Lo
2406 Constant *NegLo = ConstantExpr::getNeg(Lo);
2407 Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
2408 Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
2409 return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
2412 if (Lo == Hi) // Trivially true.
2413 return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
2415 // V < Min || V >= Hi -> V > Hi-1
2416 Hi = SubOne(cast<ConstantInt>(Hi));
2417 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
2418 ICmpInst::Predicate pred = (isSigned ?
2419 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
2420 return new ICmpInst(pred, V, Hi);
2423 // Emit V-Lo >u Hi-1-Lo
2424 // Note that Hi has already had one subtracted from it, above.
2425 ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
2426 Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
2427 Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
2428 return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
2431 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
2432 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
2433 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
2434 // not, since all 1s are not contiguous.
2435 static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
2436 const APInt& V = Val->getValue();
2437 uint32_t BitWidth = Val->getType()->getBitWidth();
2438 if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
2440 // look for the first zero bit after the run of ones
2441 MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
2442 // look for the first non-zero bit
2443 ME = V.getActiveBits();
2447 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
2448 /// where isSub determines whether the operator is a sub. If we can fold one of
2449 /// the following xforms:
2451 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
2452 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
2453 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
2455 /// return (A +/- B).
2457 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
2458 ConstantInt *Mask, bool isSub,
2460 Instruction *LHSI = dyn_cast<Instruction>(LHS);
2461 if (!LHSI || LHSI->getNumOperands() != 2 ||
2462 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
2464 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
2466 switch (LHSI->getOpcode()) {
2468 case Instruction::And:
2469 if (ConstantExpr::getAnd(N, Mask) == Mask) {
2470 // If the AndRHS is a power of two minus one (0+1+), this is simple.
2471 if ((Mask->getValue().countLeadingZeros() +
2472 Mask->getValue().countPopulation()) ==
2473 Mask->getValue().getBitWidth())
2476 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
2477 // part, we don't need any explicit masks to take them out of A. If that
2478 // is all N is, ignore it.
2479 uint32_t MB = 0, ME = 0;
2480 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
2481 uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
2482 APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
2483 if (MaskedValueIsZero(RHS, Mask))
2488 case Instruction::Or:
2489 case Instruction::Xor:
2490 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
2491 if ((Mask->getValue().countLeadingZeros() +
2492 Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
2493 && ConstantExpr::getAnd(N, Mask)->isNullValue())
2499 return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold");
2500 return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold");
2503 /// FoldAndOfICmps - Fold (icmp)&(icmp) if possible.
2504 Instruction *InstCombiner::FoldAndOfICmps(Instruction &I,
2505 ICmpInst *LHS, ICmpInst *RHS) {
2507 ConstantInt *LHSCst, *RHSCst;
2508 ICmpInst::Predicate LHSCC, RHSCC;
2510 // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
2511 if (!match(LHS, m_ICmp(LHSCC, m_Value(Val),
2512 m_ConstantInt(LHSCst))) ||
2513 !match(RHS, m_ICmp(RHSCC, m_Value(Val2),
2514 m_ConstantInt(RHSCst))))
2517 if (LHSCst == RHSCst && LHSCC == RHSCC) {
2518 // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
2519 // where C is a power of 2
2520 if (LHSCC == ICmpInst::ICMP_ULT &&
2521 LHSCst->getValue().isPowerOf2()) {
2522 Value *NewOr = Builder->CreateOr(Val, Val2);
2523 return new ICmpInst(LHSCC, NewOr, LHSCst);
2526 // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
2527 if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) {
2528 Value *NewOr = Builder->CreateOr(Val, Val2);
2529 return new ICmpInst(LHSCC, NewOr, LHSCst);
2533 // From here on, we only handle:
2534 // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
2535 if (Val != Val2) return 0;
2537 // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
2538 if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
2539 RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
2540 LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
2541 RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
2544 // We can't fold (ugt x, C) & (sgt x, C2).
2545 if (!PredicatesFoldable(LHSCC, RHSCC))
2548 // Ensure that the larger constant is on the RHS.
2550 if (CmpInst::isSigned(LHSCC) ||
2551 (ICmpInst::isEquality(LHSCC) &&
2552 CmpInst::isSigned(RHSCC)))
2553 ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
2555 ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
2558 std::swap(LHS, RHS);
2559 std::swap(LHSCst, RHSCst);
2560 std::swap(LHSCC, RHSCC);
2563 // At this point, we know we have have two icmp instructions
2564 // comparing a value against two constants and and'ing the result
2565 // together. Because of the above check, we know that we only have
2566 // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
2567 // (from the FoldICmpLogical check above), that the two constants
2568 // are not equal and that the larger constant is on the RHS
2569 assert(LHSCst != RHSCst && "Compares not folded above?");
2572 default: llvm_unreachable("Unknown integer condition code!");
2573 case ICmpInst::ICMP_EQ:
2575 default: llvm_unreachable("Unknown integer condition code!");
2576 case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
2577 case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
2578 case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
2579 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
2580 case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
2581 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
2582 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
2583 return ReplaceInstUsesWith(I, LHS);
2585 case ICmpInst::ICMP_NE:
2587 default: llvm_unreachable("Unknown integer condition code!");
2588 case ICmpInst::ICMP_ULT:
2589 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
2590 return new ICmpInst(ICmpInst::ICMP_ULT, Val, LHSCst);
2591 break; // (X != 13 & X u< 15) -> no change
2592 case ICmpInst::ICMP_SLT:
2593 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
2594 return new ICmpInst(ICmpInst::ICMP_SLT, Val, LHSCst);
2595 break; // (X != 13 & X s< 15) -> no change
2596 case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
2597 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
2598 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
2599 return ReplaceInstUsesWith(I, RHS);
2600 case ICmpInst::ICMP_NE:
2601 if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
2602 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2603 Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
2604 return new ICmpInst(ICmpInst::ICMP_UGT, Add,
2605 ConstantInt::get(Add->getType(), 1));
2607 break; // (X != 13 & X != 15) -> no change
2610 case ICmpInst::ICMP_ULT:
2612 default: llvm_unreachable("Unknown integer condition code!");
2613 case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
2614 case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
2615 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
2616 case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
2618 case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
2619 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
2620 return ReplaceInstUsesWith(I, LHS);
2621 case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
2625 case ICmpInst::ICMP_SLT:
2627 default: llvm_unreachable("Unknown integer condition code!");
2628 case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
2629 case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
2630 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
2631 case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
2633 case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
2634 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
2635 return ReplaceInstUsesWith(I, LHS);
2636 case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
2640 case ICmpInst::ICMP_UGT:
2642 default: llvm_unreachable("Unknown integer condition code!");
2643 case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15
2644 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
2645 return ReplaceInstUsesWith(I, RHS);
2646 case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
2648 case ICmpInst::ICMP_NE:
2649 if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
2650 return new ICmpInst(LHSCC, Val, RHSCst);
2651 break; // (X u> 13 & X != 15) -> no change
2652 case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
2653 return InsertRangeTest(Val, AddOne(LHSCst),
2654 RHSCst, false, true, I);
2655 case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
2659 case ICmpInst::ICMP_SGT:
2661 default: llvm_unreachable("Unknown integer condition code!");
2662 case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15
2663 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
2664 return ReplaceInstUsesWith(I, RHS);
2665 case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
2667 case ICmpInst::ICMP_NE:
2668 if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
2669 return new ICmpInst(LHSCC, Val, RHSCst);
2670 break; // (X s> 13 & X != 15) -> no change
2671 case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
2672 return InsertRangeTest(Val, AddOne(LHSCst),
2673 RHSCst, true, true, I);
2674 case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
2683 Instruction *InstCombiner::FoldAndOfFCmps(Instruction &I, FCmpInst *LHS,
2686 if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
2687 RHS->getPredicate() == FCmpInst::FCMP_ORD) {
2688 // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
2689 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
2690 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
2691 // If either of the constants are nans, then the whole thing returns
2693 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
2694 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
2695 return new FCmpInst(FCmpInst::FCMP_ORD,
2696 LHS->getOperand(0), RHS->getOperand(0));
2699 // Handle vector zeros. This occurs because the canonical form of
2700 // "fcmp ord x,x" is "fcmp ord x, 0".
2701 if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
2702 isa<ConstantAggregateZero>(RHS->getOperand(1)))
2703 return new FCmpInst(FCmpInst::FCMP_ORD,
2704 LHS->getOperand(0), RHS->getOperand(0));
2708 Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
2709 Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
2710 FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
2713 if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
2714 // Swap RHS operands to match LHS.
2715 Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
2716 std::swap(Op1LHS, Op1RHS);
2719 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
2720 // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
2722 return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
2724 if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE)
2725 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
2726 if (Op0CC == FCmpInst::FCMP_TRUE)
2727 return ReplaceInstUsesWith(I, RHS);
2728 if (Op1CC == FCmpInst::FCMP_TRUE)
2729 return ReplaceInstUsesWith(I, LHS);
2733 unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
2734 unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
2736 std::swap(LHS, RHS);
2737 std::swap(Op0Pred, Op1Pred);
2738 std::swap(Op0Ordered, Op1Ordered);
2741 // uno && ueq -> uno && (uno || eq) -> ueq
2742 // ord && olt -> ord && (ord && lt) -> olt
2743 if (Op0Ordered == Op1Ordered)
2744 return ReplaceInstUsesWith(I, RHS);
2746 // uno && oeq -> uno && (ord && eq) -> false
2747 // uno && ord -> false
2749 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
2750 // ord && ueq -> ord && (uno || eq) -> oeq
2751 return cast<Instruction>(getFCmpValue(true, Op1Pred, Op0LHS, Op0RHS));
2759 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
2760 bool Changed = SimplifyCommutative(I);
2761 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2763 if (Value *V = SimplifyAndInst(Op0, Op1, TD))
2764 return ReplaceInstUsesWith(I, V);
2766 // See if we can simplify any instructions used by the instruction whose sole
2767 // purpose is to compute bits we don't care about.
2768 if (SimplifyDemandedInstructionBits(I))
2771 if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
2772 const APInt &AndRHSMask = AndRHS->getValue();
2773 APInt NotAndRHS(~AndRHSMask);
2775 // Optimize a variety of ((val OP C1) & C2) combinations...
2776 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2777 Value *Op0LHS = Op0I->getOperand(0);
2778 Value *Op0RHS = Op0I->getOperand(1);
2779 switch (Op0I->getOpcode()) {
2781 case Instruction::Xor:
2782 case Instruction::Or:
2783 // If the mask is only needed on one incoming arm, push it up.
2784 if (!Op0I->hasOneUse()) break;
2786 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
2787 // Not masking anything out for the LHS, move to RHS.
2788 Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS,
2789 Op0RHS->getName()+".masked");
2790 return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS);
2792 if (!isa<Constant>(Op0RHS) &&
2793 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
2794 // Not masking anything out for the RHS, move to LHS.
2795 Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS,
2796 Op0LHS->getName()+".masked");
2797 return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS);
2801 case Instruction::Add:
2802 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
2803 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
2804 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
2805 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
2806 return BinaryOperator::CreateAnd(V, AndRHS);
2807 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
2808 return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes
2811 case Instruction::Sub:
2812 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
2813 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
2814 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
2815 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
2816 return BinaryOperator::CreateAnd(V, AndRHS);
2818 // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
2819 // has 1's for all bits that the subtraction with A might affect.
2820 if (Op0I->hasOneUse()) {
2821 uint32_t BitWidth = AndRHSMask.getBitWidth();
2822 uint32_t Zeros = AndRHSMask.countLeadingZeros();
2823 APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
2825 ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS);
2826 if (!(A && A->isZero()) && // avoid infinite recursion.
2827 MaskedValueIsZero(Op0LHS, Mask)) {
2828 Value *NewNeg = Builder->CreateNeg(Op0RHS);
2829 return BinaryOperator::CreateAnd(NewNeg, AndRHS);
2834 case Instruction::Shl:
2835 case Instruction::LShr:
2836 // (1 << x) & 1 --> zext(x == 0)
2837 // (1 >> x) & 1 --> zext(x == 0)
2838 if (AndRHSMask == 1 && Op0LHS == AndRHS) {
2840 Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType()));
2841 return new ZExtInst(NewICmp, I.getType());
2846 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2847 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
2849 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
2850 // If this is an integer truncation or change from signed-to-unsigned, and
2851 // if the source is an and/or with immediate, transform it. This
2852 // frequently occurs for bitfield accesses.
2853 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
2854 if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
2855 CastOp->getNumOperands() == 2)
2856 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1))){
2857 if (CastOp->getOpcode() == Instruction::And) {
2858 // Change: and (cast (and X, C1) to T), C2
2859 // into : and (cast X to T), trunc_or_bitcast(C1)&C2
2860 // This will fold the two constants together, which may allow
2861 // other simplifications.
2862 Value *NewCast = Builder->CreateTruncOrBitCast(
2863 CastOp->getOperand(0), I.getType(),
2864 CastOp->getName()+".shrunk");
2865 // trunc_or_bitcast(C1)&C2
2866 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
2867 C3 = ConstantExpr::getAnd(C3, AndRHS);
2868 return BinaryOperator::CreateAnd(NewCast, C3);
2869 } else if (CastOp->getOpcode() == Instruction::Or) {
2870 // Change: and (cast (or X, C1) to T), C2
2871 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
2872 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
2873 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS)
2875 return ReplaceInstUsesWith(I, AndRHS);
2881 // Try to fold constant and into select arguments.
2882 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2883 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2885 if (isa<PHINode>(Op0))
2886 if (Instruction *NV = FoldOpIntoPhi(I))
2891 // (~A & ~B) == (~(A | B)) - De Morgan's Law
2892 if (Value *Op0NotVal = dyn_castNotVal(Op0))
2893 if (Value *Op1NotVal = dyn_castNotVal(Op1))
2894 if (Op0->hasOneUse() && Op1->hasOneUse()) {
2895 Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal,
2896 I.getName()+".demorgan");
2897 return BinaryOperator::CreateNot(Or);
2901 Value *A = 0, *B = 0, *C = 0, *D = 0;
2902 // (A|B) & ~(A&B) -> A^B
2903 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
2904 match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) &&
2905 ((A == C && B == D) || (A == D && B == C)))
2906 return BinaryOperator::CreateXor(A, B);
2908 // ~(A&B) & (A|B) -> A^B
2909 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
2910 match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) &&
2911 ((A == C && B == D) || (A == D && B == C)))
2912 return BinaryOperator::CreateXor(A, B);
2914 if (Op0->hasOneUse() &&
2915 match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
2916 if (A == Op1) { // (A^B)&A -> A&(A^B)
2917 I.swapOperands(); // Simplify below
2918 std::swap(Op0, Op1);
2919 } else if (B == Op1) { // (A^B)&B -> B&(B^A)
2920 cast<BinaryOperator>(Op0)->swapOperands();
2921 I.swapOperands(); // Simplify below
2922 std::swap(Op0, Op1);
2926 if (Op1->hasOneUse() &&
2927 match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
2928 if (B == Op0) { // B&(A^B) -> B&(B^A)
2929 cast<BinaryOperator>(Op1)->swapOperands();
2932 if (A == Op0) // A&(A^B) -> A & ~B
2933 return BinaryOperator::CreateAnd(A, Builder->CreateNot(B, "tmp"));
2936 // (A&((~A)|B)) -> A&B
2937 if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
2938 match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
2939 return BinaryOperator::CreateAnd(A, Op1);
2940 if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
2941 match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
2942 return BinaryOperator::CreateAnd(A, Op0);
2945 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
2946 // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
2947 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
2950 if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0))
2951 if (Instruction *Res = FoldAndOfICmps(I, LHS, RHS))
2955 // fold (and (cast A), (cast B)) -> (cast (and A, B))
2956 if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
2957 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
2958 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
2959 const Type *SrcTy = Op0C->getOperand(0)->getType();
2960 if (SrcTy == Op1C->getOperand(0)->getType() &&
2961 SrcTy->isIntOrIntVector() &&
2962 // Only do this if the casts both really cause code to be generated.
2963 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
2965 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
2967 Value *NewOp = Builder->CreateAnd(Op0C->getOperand(0),
2968 Op1C->getOperand(0), I.getName());
2969 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
2973 // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
2974 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
2975 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
2976 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
2977 SI0->getOperand(1) == SI1->getOperand(1) &&
2978 (SI0->hasOneUse() || SI1->hasOneUse())) {
2980 Builder->CreateAnd(SI0->getOperand(0), SI1->getOperand(0),
2982 return BinaryOperator::Create(SI1->getOpcode(), NewOp,
2983 SI1->getOperand(1));
2987 // If and'ing two fcmp, try combine them into one.
2988 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
2989 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
2990 if (Instruction *Res = FoldAndOfFCmps(I, LHS, RHS))
2994 return Changed ? &I : 0;
2997 /// CollectBSwapParts - Analyze the specified subexpression and see if it is
2998 /// capable of providing pieces of a bswap. The subexpression provides pieces
2999 /// of a bswap if it is proven that each of the non-zero bytes in the output of
3000 /// the expression came from the corresponding "byte swapped" byte in some other
3001 /// value. For example, if the current subexpression is "(shl i32 %X, 24)" then
3002 /// we know that the expression deposits the low byte of %X into the high byte
3003 /// of the bswap result and that all other bytes are zero. This expression is
3004 /// accepted, the high byte of ByteValues is set to X to indicate a correct
3007 /// This function returns true if the match was unsuccessful and false if so.
3008 /// On entry to the function the "OverallLeftShift" is a signed integer value
3009 /// indicating the number of bytes that the subexpression is later shifted. For
3010 /// example, if the expression is later right shifted by 16 bits, the
3011 /// OverallLeftShift value would be -2 on entry. This is used to specify which
3012 /// byte of ByteValues is actually being set.
3014 /// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding
3015 /// byte is masked to zero by a user. For example, in (X & 255), X will be
3016 /// processed with a bytemask of 1. Because bytemask is 32-bits, this limits
3017 /// this function to working on up to 32-byte (256 bit) values. ByteMask is
3018 /// always in the local (OverallLeftShift) coordinate space.
3020 static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask,
3021 SmallVector<Value*, 8> &ByteValues) {
3022 if (Instruction *I = dyn_cast<Instruction>(V)) {
3023 // If this is an or instruction, it may be an inner node of the bswap.
3024 if (I->getOpcode() == Instruction::Or) {
3025 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
3027 CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask,
3031 // If this is a logical shift by a constant multiple of 8, recurse with
3032 // OverallLeftShift and ByteMask adjusted.
3033 if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
3035 cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
3036 // Ensure the shift amount is defined and of a byte value.
3037 if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size()))
3040 unsigned ByteShift = ShAmt >> 3;
3041 if (I->getOpcode() == Instruction::Shl) {
3042 // X << 2 -> collect(X, +2)
3043 OverallLeftShift += ByteShift;
3044 ByteMask >>= ByteShift;
3046 // X >>u 2 -> collect(X, -2)
3047 OverallLeftShift -= ByteShift;
3048 ByteMask <<= ByteShift;
3049 ByteMask &= (~0U >> (32-ByteValues.size()));
3052 if (OverallLeftShift >= (int)ByteValues.size()) return true;
3053 if (OverallLeftShift <= -(int)ByteValues.size()) return true;
3055 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
3059 // If this is a logical 'and' with a mask that clears bytes, clear the
3060 // corresponding bytes in ByteMask.
3061 if (I->getOpcode() == Instruction::And &&
3062 isa<ConstantInt>(I->getOperand(1))) {
3063 // Scan every byte of the and mask, seeing if the byte is either 0 or 255.
3064 unsigned NumBytes = ByteValues.size();
3065 APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255);
3066 const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
3068 for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) {
3069 // If this byte is masked out by a later operation, we don't care what
3071 if ((ByteMask & (1 << i)) == 0)
3074 // If the AndMask is all zeros for this byte, clear the bit.
3075 APInt MaskB = AndMask & Byte;
3077 ByteMask &= ~(1U << i);
3081 // If the AndMask is not all ones for this byte, it's not a bytezap.
3085 // Otherwise, this byte is kept.
3088 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
3093 // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be
3094 // the input value to the bswap. Some observations: 1) if more than one byte
3095 // is demanded from this input, then it could not be successfully assembled
3096 // into a byteswap. At least one of the two bytes would not be aligned with
3097 // their ultimate destination.
3098 if (!isPowerOf2_32(ByteMask)) return true;
3099 unsigned InputByteNo = CountTrailingZeros_32(ByteMask);
3101 // 2) The input and ultimate destinations must line up: if byte 3 of an i32
3102 // is demanded, it needs to go into byte 0 of the result. This means that the
3103 // byte needs to be shifted until it lands in the right byte bucket. The
3104 // shift amount depends on the position: if the byte is coming from the high
3105 // part of the value (e.g. byte 3) then it must be shifted right. If from the
3106 // low part, it must be shifted left.
3107 unsigned DestByteNo = InputByteNo + OverallLeftShift;
3108 if (InputByteNo < ByteValues.size()/2) {
3109 if (ByteValues.size()-1-DestByteNo != InputByteNo)
3112 if (ByteValues.size()-1-DestByteNo != InputByteNo)
3116 // If the destination byte value is already defined, the values are or'd
3117 // together, which isn't a bswap (unless it's an or of the same bits).
3118 if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V)
3120 ByteValues[DestByteNo] = V;
3124 /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
3125 /// If so, insert the new bswap intrinsic and return it.
3126 Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
3127 const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
3128 if (!ITy || ITy->getBitWidth() % 16 ||
3129 // ByteMask only allows up to 32-byte values.
3130 ITy->getBitWidth() > 32*8)
3131 return 0; // Can only bswap pairs of bytes. Can't do vectors.
3133 /// ByteValues - For each byte of the result, we keep track of which value
3134 /// defines each byte.
3135 SmallVector<Value*, 8> ByteValues;
3136 ByteValues.resize(ITy->getBitWidth()/8);
3138 // Try to find all the pieces corresponding to the bswap.
3139 uint32_t ByteMask = ~0U >> (32-ByteValues.size());
3140 if (CollectBSwapParts(&I, 0, ByteMask, ByteValues))
3143 // Check to see if all of the bytes come from the same value.
3144 Value *V = ByteValues[0];
3145 if (V == 0) return 0; // Didn't find a byte? Must be zero.
3147 // Check to make sure that all of the bytes come from the same value.
3148 for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
3149 if (ByteValues[i] != V)
3151 const Type *Tys[] = { ITy };
3152 Module *M = I.getParent()->getParent()->getParent();
3153 Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
3154 return CallInst::Create(F, V);
3157 /// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check
3158 /// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then
3159 /// we can simplify this expression to "cond ? C : D or B".
3160 static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
3161 Value *C, Value *D) {
3162 // If A is not a select of -1/0, this cannot match.
3164 if (!match(A, m_SelectCst<-1, 0>(m_Value(Cond))))
3167 // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
3168 if (match(D, m_SelectCst<0, -1>(m_Specific(Cond))))
3169 return SelectInst::Create(Cond, C, B);
3170 if (match(D, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
3171 return SelectInst::Create(Cond, C, B);
3172 // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
3173 if (match(B, m_SelectCst<0, -1>(m_Specific(Cond))))
3174 return SelectInst::Create(Cond, C, D);
3175 if (match(B, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
3176 return SelectInst::Create(Cond, C, D);
3180 /// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
3181 Instruction *InstCombiner::FoldOrOfICmps(Instruction &I,
3182 ICmpInst *LHS, ICmpInst *RHS) {
3184 ConstantInt *LHSCst, *RHSCst;
3185 ICmpInst::Predicate LHSCC, RHSCC;
3187 // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
3188 if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) ||
3189 !match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst))))
3193 // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
3194 if (LHSCst == RHSCst && LHSCC == RHSCC &&
3195 LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
3196 Value *NewOr = Builder->CreateOr(Val, Val2);
3197 return new ICmpInst(LHSCC, NewOr, LHSCst);
3200 // From here on, we only handle:
3201 // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
3202 if (Val != Val2) return 0;
3204 // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
3205 if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
3206 RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
3207 LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
3208 RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
3211 // We can't fold (ugt x, C) | (sgt x, C2).
3212 if (!PredicatesFoldable(LHSCC, RHSCC))
3215 // Ensure that the larger constant is on the RHS.
3217 if (CmpInst::isSigned(LHSCC) ||
3218 (ICmpInst::isEquality(LHSCC) &&
3219 CmpInst::isSigned(RHSCC)))
3220 ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
3222 ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
3225 std::swap(LHS, RHS);
3226 std::swap(LHSCst, RHSCst);
3227 std::swap(LHSCC, RHSCC);
3230 // At this point, we know we have have two icmp instructions
3231 // comparing a value against two constants and or'ing the result
3232 // together. Because of the above check, we know that we only have
3233 // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
3234 // FoldICmpLogical check above), that the two constants are not
3236 assert(LHSCst != RHSCst && "Compares not folded above?");
3239 default: llvm_unreachable("Unknown integer condition code!");
3240 case ICmpInst::ICMP_EQ:
3242 default: llvm_unreachable("Unknown integer condition code!");
3243 case ICmpInst::ICMP_EQ:
3244 if (LHSCst == SubOne(RHSCst)) {
3245 // (X == 13 | X == 14) -> X-13 <u 2
3246 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
3247 Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
3248 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
3249 return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
3251 break; // (X == 13 | X == 15) -> no change
3252 case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
3253 case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
3255 case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
3256 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
3257 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
3258 return ReplaceInstUsesWith(I, RHS);
3261 case ICmpInst::ICMP_NE:
3263 default: llvm_unreachable("Unknown integer condition code!");
3264 case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
3265 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
3266 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
3267 return ReplaceInstUsesWith(I, LHS);
3268 case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
3269 case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
3270 case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
3271 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
3274 case ICmpInst::ICMP_ULT:
3276 default: llvm_unreachable("Unknown integer condition code!");
3277 case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
3279 case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
3280 // If RHSCst is [us]MAXINT, it is always false. Not handling
3281 // this can cause overflow.
3282 if (RHSCst->isMaxValue(false))
3283 return ReplaceInstUsesWith(I, LHS);
3284 return InsertRangeTest(Val, LHSCst, AddOne(RHSCst),
3286 case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
3288 case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
3289 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
3290 return ReplaceInstUsesWith(I, RHS);
3291 case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
3295 case ICmpInst::ICMP_SLT:
3297 default: llvm_unreachable("Unknown integer condition code!");
3298 case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
3300 case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
3301 // If RHSCst is [us]MAXINT, it is always false. Not handling
3302 // this can cause overflow.
3303 if (RHSCst->isMaxValue(true))
3304 return ReplaceInstUsesWith(I, LHS);
3305 return InsertRangeTest(Val, LHSCst, AddOne(RHSCst),
3307 case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
3309 case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
3310 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
3311 return ReplaceInstUsesWith(I, RHS);
3312 case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
3316 case ICmpInst::ICMP_UGT:
3318 default: llvm_unreachable("Unknown integer condition code!");
3319 case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
3320 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
3321 return ReplaceInstUsesWith(I, LHS);
3322 case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
3324 case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
3325 case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
3326 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
3327 case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
3331 case ICmpInst::ICMP_SGT:
3333 default: llvm_unreachable("Unknown integer condition code!");
3334 case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
3335 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
3336 return ReplaceInstUsesWith(I, LHS);
3337 case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
3339 case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
3340 case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
3341 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
3342 case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
3350 Instruction *InstCombiner::FoldOrOfFCmps(Instruction &I, FCmpInst *LHS,
3352 if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
3353 RHS->getPredicate() == FCmpInst::FCMP_UNO &&
3354 LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
3355 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
3356 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
3357 // If either of the constants are nans, then the whole thing returns
3359 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
3360 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
3362 // Otherwise, no need to compare the two constants, compare the
3364 return new FCmpInst(FCmpInst::FCMP_UNO,
3365 LHS->getOperand(0), RHS->getOperand(0));
3368 // Handle vector zeros. This occurs because the canonical form of
3369 // "fcmp uno x,x" is "fcmp uno x, 0".
3370 if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
3371 isa<ConstantAggregateZero>(RHS->getOperand(1)))
3372 return new FCmpInst(FCmpInst::FCMP_UNO,
3373 LHS->getOperand(0), RHS->getOperand(0));
3378 Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
3379 Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
3380 FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
3382 if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
3383 // Swap RHS operands to match LHS.
3384 Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
3385 std::swap(Op1LHS, Op1RHS);
3387 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
3388 // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
3390 return new FCmpInst((FCmpInst::Predicate)Op0CC,
3392 if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE)
3393 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
3394 if (Op0CC == FCmpInst::FCMP_FALSE)
3395 return ReplaceInstUsesWith(I, RHS);
3396 if (Op1CC == FCmpInst::FCMP_FALSE)
3397 return ReplaceInstUsesWith(I, LHS);
3400 unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
3401 unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
3402 if (Op0Ordered == Op1Ordered) {
3403 // If both are ordered or unordered, return a new fcmp with
3404 // or'ed predicates.
3405 Value *RV = getFCmpValue(Op0Ordered, Op0Pred|Op1Pred, Op0LHS, Op0RHS);
3406 if (Instruction *I = dyn_cast<Instruction>(RV))
3408 // Otherwise, it's a constant boolean value...
3409 return ReplaceInstUsesWith(I, RV);
3415 /// FoldOrWithConstants - This helper function folds:
3417 /// ((A | B) & C1) | (B & C2)
3423 /// when the XOR of the two constants is "all ones" (-1).
3424 Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
3425 Value *A, Value *B, Value *C) {
3426 ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
3430 ConstantInt *CI2 = 0;
3431 if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0;
3433 APInt Xor = CI1->getValue() ^ CI2->getValue();
3434 if (!Xor.isAllOnesValue()) return 0;
3436 if (V1 == A || V1 == B) {
3437 Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1);
3438 return BinaryOperator::CreateOr(NewOp, V1);
3444 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
3445 bool Changed = SimplifyCommutative(I);
3446 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3448 if (Value *V = SimplifyOrInst(Op0, Op1, TD))
3449 return ReplaceInstUsesWith(I, V);
3452 // See if we can simplify any instructions used by the instruction whose sole
3453 // purpose is to compute bits we don't care about.
3454 if (SimplifyDemandedInstructionBits(I))
3457 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3458 ConstantInt *C1 = 0; Value *X = 0;
3459 // (X & C1) | C2 --> (X | C2) & (C1|C2)
3460 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) &&
3462 Value *Or = Builder->CreateOr(X, RHS);
3464 return BinaryOperator::CreateAnd(Or,
3465 ConstantInt::get(I.getContext(),
3466 RHS->getValue() | C1->getValue()));
3469 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
3470 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) &&
3472 Value *Or = Builder->CreateOr(X, RHS);
3474 return BinaryOperator::CreateXor(Or,
3475 ConstantInt::get(I.getContext(),
3476 C1->getValue() & ~RHS->getValue()));
3479 // Try to fold constant and into select arguments.
3480 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3481 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3483 if (isa<PHINode>(Op0))
3484 if (Instruction *NV = FoldOpIntoPhi(I))
3488 Value *A = 0, *B = 0;
3489 ConstantInt *C1 = 0, *C2 = 0;
3491 // (A | B) | C and A | (B | C) -> bswap if possible.
3492 // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
3493 if (match(Op0, m_Or(m_Value(), m_Value())) ||
3494 match(Op1, m_Or(m_Value(), m_Value())) ||
3495 (match(Op0, m_Shift(m_Value(), m_Value())) &&
3496 match(Op1, m_Shift(m_Value(), m_Value())))) {
3497 if (Instruction *BSwap = MatchBSwap(I))
3501 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
3502 if (Op0->hasOneUse() &&
3503 match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
3504 MaskedValueIsZero(Op1, C1->getValue())) {
3505 Value *NOr = Builder->CreateOr(A, Op1);
3507 return BinaryOperator::CreateXor(NOr, C1);
3510 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
3511 if (Op1->hasOneUse() &&
3512 match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
3513 MaskedValueIsZero(Op0, C1->getValue())) {
3514 Value *NOr = Builder->CreateOr(A, Op0);
3516 return BinaryOperator::CreateXor(NOr, C1);
3520 Value *C = 0, *D = 0;
3521 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
3522 match(Op1, m_And(m_Value(B), m_Value(D)))) {
3523 Value *V1 = 0, *V2 = 0, *V3 = 0;
3524 C1 = dyn_cast<ConstantInt>(C);
3525 C2 = dyn_cast<ConstantInt>(D);
3526 if (C1 && C2) { // (A & C1)|(B & C2)
3527 // If we have: ((V + N) & C1) | (V & C2)
3528 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
3529 // replace with V+N.
3530 if (C1->getValue() == ~C2->getValue()) {
3531 if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
3532 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
3533 // Add commutes, try both ways.
3534 if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
3535 return ReplaceInstUsesWith(I, A);
3536 if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
3537 return ReplaceInstUsesWith(I, A);
3539 // Or commutes, try both ways.
3540 if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
3541 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
3542 // Add commutes, try both ways.
3543 if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
3544 return ReplaceInstUsesWith(I, B);
3545 if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
3546 return ReplaceInstUsesWith(I, B);
3550 // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2)
3551 // iff (C1&C2) == 0 and (N&~C1) == 0
3552 if ((C1->getValue() & C2->getValue()) == 0) {
3553 if (match(A, m_Or(m_Value(V1), m_Value(V2))) &&
3554 ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue())) || // (V|N)
3555 (V2 == B && MaskedValueIsZero(V1, ~C1->getValue())))) // (N|V)
3556 return BinaryOperator::CreateAnd(A,
3557 ConstantInt::get(A->getContext(),
3558 C1->getValue()|C2->getValue()));
3559 // Or commutes, try both ways.
3560 if (match(B, m_Or(m_Value(V1), m_Value(V2))) &&
3561 ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue())) || // (V|N)
3562 (V2 == A && MaskedValueIsZero(V1, ~C2->getValue())))) // (N|V)
3563 return BinaryOperator::CreateAnd(B,
3564 ConstantInt::get(B->getContext(),
3565 C1->getValue()|C2->getValue()));
3569 // Check to see if we have any common things being and'ed. If so, find the
3570 // terms for V1 & (V2|V3).
3571 if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
3573 if (A == B) // (A & C)|(A & D) == A & (C|D)
3574 V1 = A, V2 = C, V3 = D;
3575 else if (A == D) // (A & C)|(B & A) == A & (B|C)
3576 V1 = A, V2 = B, V3 = C;
3577 else if (C == B) // (A & C)|(C & D) == C & (A|D)
3578 V1 = C, V2 = A, V3 = D;
3579 else if (C == D) // (A & C)|(B & C) == C & (A|B)
3580 V1 = C, V2 = A, V3 = B;
3583 Value *Or = Builder->CreateOr(V2, V3, "tmp");
3584 return BinaryOperator::CreateAnd(V1, Or);
3588 // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants
3589 if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D))
3591 if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C))
3593 if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D))
3595 if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C))
3598 // ((A&~B)|(~A&B)) -> A^B
3599 if ((match(C, m_Not(m_Specific(D))) &&
3600 match(B, m_Not(m_Specific(A)))))
3601 return BinaryOperator::CreateXor(A, D);
3602 // ((~B&A)|(~A&B)) -> A^B
3603 if ((match(A, m_Not(m_Specific(D))) &&
3604 match(B, m_Not(m_Specific(C)))))
3605 return BinaryOperator::CreateXor(C, D);
3606 // ((A&~B)|(B&~A)) -> A^B
3607 if ((match(C, m_Not(m_Specific(B))) &&
3608 match(D, m_Not(m_Specific(A)))))
3609 return BinaryOperator::CreateXor(A, B);
3610 // ((~B&A)|(B&~A)) -> A^B
3611 if ((match(A, m_Not(m_Specific(B))) &&
3612 match(D, m_Not(m_Specific(C)))))
3613 return BinaryOperator::CreateXor(C, B);
3616 // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
3617 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
3618 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
3619 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
3620 SI0->getOperand(1) == SI1->getOperand(1) &&
3621 (SI0->hasOneUse() || SI1->hasOneUse())) {
3622 Value *NewOp = Builder->CreateOr(SI0->getOperand(0), SI1->getOperand(0),
3624 return BinaryOperator::Create(SI1->getOpcode(), NewOp,
3625 SI1->getOperand(1));
3629 // ((A|B)&1)|(B&-2) -> (A&1) | B
3630 if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
3631 match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
3632 Instruction *Ret = FoldOrWithConstants(I, Op1, A, B, C);
3633 if (Ret) return Ret;
3635 // (B&-2)|((A|B)&1) -> (A&1) | B
3636 if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
3637 match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
3638 Instruction *Ret = FoldOrWithConstants(I, Op0, A, B, C);
3639 if (Ret) return Ret;
3642 // (~A | ~B) == (~(A & B)) - De Morgan's Law
3643 if (Value *Op0NotVal = dyn_castNotVal(Op0))
3644 if (Value *Op1NotVal = dyn_castNotVal(Op1))
3645 if (Op0->hasOneUse() && Op1->hasOneUse()) {
3646 Value *And = Builder->CreateAnd(Op0NotVal, Op1NotVal,
3647 I.getName()+".demorgan");
3648 return BinaryOperator::CreateNot(And);
3651 // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
3652 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
3653 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
3656 if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
3657 if (Instruction *Res = FoldOrOfICmps(I, LHS, RHS))
3661 // fold (or (cast A), (cast B)) -> (cast (or A, B))
3662 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
3663 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
3664 if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
3665 if (!isa<ICmpInst>(Op0C->getOperand(0)) ||
3666 !isa<ICmpInst>(Op1C->getOperand(0))) {
3667 const Type *SrcTy = Op0C->getOperand(0)->getType();
3668 if (SrcTy == Op1C->getOperand(0)->getType() &&
3669 SrcTy->isIntOrIntVector() &&
3670 // Only do this if the casts both really cause code to be
3672 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
3674 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
3676 Value *NewOp = Builder->CreateOr(Op0C->getOperand(0),
3677 Op1C->getOperand(0), I.getName());
3678 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
3685 // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
3686 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
3687 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
3688 if (Instruction *Res = FoldOrOfFCmps(I, LHS, RHS))
3692 return Changed ? &I : 0;
3697 // XorSelf - Implements: X ^ X --> 0
3700 XorSelf(Value *rhs) : RHS(rhs) {}
3701 bool shouldApply(Value *LHS) const { return LHS == RHS; }
3702 Instruction *apply(BinaryOperator &Xor) const {
3709 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
3710 bool Changed = SimplifyCommutative(I);
3711 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3713 if (isa<UndefValue>(Op1)) {
3714 if (isa<UndefValue>(Op0))
3715 // Handle undef ^ undef -> 0 special case. This is a common
3717 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3718 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
3721 // xor X, X = 0, even if X is nested in a sequence of Xor's.
3722 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
3723 assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
3724 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3727 // See if we can simplify any instructions used by the instruction whose sole
3728 // purpose is to compute bits we don't care about.
3729 if (SimplifyDemandedInstructionBits(I))
3731 if (isa<VectorType>(I.getType()))
3732 if (isa<ConstantAggregateZero>(Op1))
3733 return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X
3735 // Is this a ~ operation?
3736 if (Value *NotOp = dyn_castNotVal(&I)) {
3737 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
3738 if (Op0I->getOpcode() == Instruction::And ||
3739 Op0I->getOpcode() == Instruction::Or) {
3740 // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
3741 // ~(~X | Y) === (X & ~Y) - De Morgan's Law
3742 if (dyn_castNotVal(Op0I->getOperand(1)))
3743 Op0I->swapOperands();
3744 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
3746 Builder->CreateNot(Op0I->getOperand(1),
3747 Op0I->getOperand(1)->getName()+".not");
3748 if (Op0I->getOpcode() == Instruction::And)
3749 return BinaryOperator::CreateOr(Op0NotVal, NotY);
3750 return BinaryOperator::CreateAnd(Op0NotVal, NotY);
3753 // ~(X & Y) --> (~X | ~Y) - De Morgan's Law
3754 // ~(X | Y) === (~X & ~Y) - De Morgan's Law
3755 if (isFreeToInvert(Op0I->getOperand(0)) &&
3756 isFreeToInvert(Op0I->getOperand(1))) {
3758 Builder->CreateNot(Op0I->getOperand(0), "notlhs");
3760 Builder->CreateNot(Op0I->getOperand(1), "notrhs");
3761 if (Op0I->getOpcode() == Instruction::And)
3762 return BinaryOperator::CreateOr(NotX, NotY);
3763 return BinaryOperator::CreateAnd(NotX, NotY);
3770 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3771 if (RHS->isOne() && Op0->hasOneUse()) {
3772 // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
3773 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
3774 return new ICmpInst(ICI->getInversePredicate(),
3775 ICI->getOperand(0), ICI->getOperand(1));
3777 if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
3778 return new FCmpInst(FCI->getInversePredicate(),
3779 FCI->getOperand(0), FCI->getOperand(1));
3782 // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
3783 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
3784 if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
3785 if (CI->hasOneUse() && Op0C->hasOneUse()) {
3786 Instruction::CastOps Opcode = Op0C->getOpcode();
3787 if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) &&
3788 (RHS == ConstantExpr::getCast(Opcode,
3789 ConstantInt::getTrue(I.getContext()),
3790 Op0C->getDestTy()))) {
3791 CI->setPredicate(CI->getInversePredicate());
3792 return CastInst::Create(Opcode, CI, Op0C->getType());
3798 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
3799 // ~(c-X) == X-c-1 == X+(-c-1)
3800 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
3801 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
3802 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
3803 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
3804 ConstantInt::get(I.getType(), 1));
3805 return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
3808 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
3809 if (Op0I->getOpcode() == Instruction::Add) {
3810 // ~(X-c) --> (-c-1)-X
3811 if (RHS->isAllOnesValue()) {
3812 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
3813 return BinaryOperator::CreateSub(
3814 ConstantExpr::getSub(NegOp0CI,
3815 ConstantInt::get(I.getType(), 1)),
3816 Op0I->getOperand(0));
3817 } else if (RHS->getValue().isSignBit()) {
3818 // (X + C) ^ signbit -> (X + C + signbit)
3819 Constant *C = ConstantInt::get(I.getContext(),
3820 RHS->getValue() + Op0CI->getValue());
3821 return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
3824 } else if (Op0I->getOpcode() == Instruction::Or) {
3825 // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
3826 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
3827 Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
3828 // Anything in both C1 and C2 is known to be zero, remove it from
3830 Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
3831 NewRHS = ConstantExpr::getAnd(NewRHS,
3832 ConstantExpr::getNot(CommonBits));
3834 I.setOperand(0, Op0I->getOperand(0));
3835 I.setOperand(1, NewRHS);
3842 // Try to fold constant and into select arguments.
3843 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3844 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3846 if (isa<PHINode>(Op0))
3847 if (Instruction *NV = FoldOpIntoPhi(I))
3851 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
3853 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
3855 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
3857 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
3860 BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
3863 if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
3864 if (A == Op0) { // B^(B|A) == (A|B)^B
3865 Op1I->swapOperands();
3867 std::swap(Op0, Op1);
3868 } else if (B == Op0) { // B^(A|B) == (A|B)^B
3869 I.swapOperands(); // Simplified below.
3870 std::swap(Op0, Op1);
3872 } else if (match(Op1I, m_Xor(m_Specific(Op0), m_Value(B)))) {
3873 return ReplaceInstUsesWith(I, B); // A^(A^B) == B
3874 } else if (match(Op1I, m_Xor(m_Value(A), m_Specific(Op0)))) {
3875 return ReplaceInstUsesWith(I, A); // A^(B^A) == B
3876 } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) &&
3878 if (A == Op0) { // A^(A&B) -> A^(B&A)
3879 Op1I->swapOperands();
3882 if (B == Op0) { // A^(B&A) -> (B&A)^A
3883 I.swapOperands(); // Simplified below.
3884 std::swap(Op0, Op1);
3889 BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
3892 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
3893 Op0I->hasOneUse()) {
3894 if (A == Op1) // (B|A)^B == (A|B)^B
3896 if (B == Op1) // (A|B)^B == A & ~B
3897 return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1, "tmp"));
3898 } else if (match(Op0I, m_Xor(m_Specific(Op1), m_Value(B)))) {
3899 return ReplaceInstUsesWith(I, B); // (A^B)^A == B
3900 } else if (match(Op0I, m_Xor(m_Value(A), m_Specific(Op1)))) {
3901 return ReplaceInstUsesWith(I, A); // (B^A)^A == B
3902 } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
3904 if (A == Op1) // (A&B)^A -> (B&A)^A
3906 if (B == Op1 && // (B&A)^A == ~B & A
3907 !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
3908 return BinaryOperator::CreateAnd(Builder->CreateNot(A, "tmp"), Op1);
3913 // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
3914 if (Op0I && Op1I && Op0I->isShift() &&
3915 Op0I->getOpcode() == Op1I->getOpcode() &&
3916 Op0I->getOperand(1) == Op1I->getOperand(1) &&
3917 (Op1I->hasOneUse() || Op1I->hasOneUse())) {
3919 Builder->CreateXor(Op0I->getOperand(0), Op1I->getOperand(0),
3921 return BinaryOperator::Create(Op1I->getOpcode(), NewOp,
3922 Op1I->getOperand(1));
3926 Value *A, *B, *C, *D;
3927 // (A & B)^(A | B) -> A ^ B
3928 if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
3929 match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
3930 if ((A == C && B == D) || (A == D && B == C))
3931 return BinaryOperator::CreateXor(A, B);
3933 // (A | B)^(A & B) -> A ^ B
3934 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
3935 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
3936 if ((A == C && B == D) || (A == D && B == C))
3937 return BinaryOperator::CreateXor(A, B);
3941 if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
3942 match(Op0I, m_And(m_Value(A), m_Value(B))) &&
3943 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
3944 // (X & Y)^(X & Y) -> (Y^Z) & X
3945 Value *X = 0, *Y = 0, *Z = 0;
3947 X = A, Y = B, Z = D;
3949 X = A, Y = B, Z = C;
3951 X = B, Y = A, Z = D;
3953 X = B, Y = A, Z = C;
3956 Value *NewOp = Builder->CreateXor(Y, Z, Op0->getName());
3957 return BinaryOperator::CreateAnd(NewOp, X);
3962 // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
3963 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
3964 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
3967 // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
3968 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
3969 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
3970 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
3971 const Type *SrcTy = Op0C->getOperand(0)->getType();
3972 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
3973 // Only do this if the casts both really cause code to be generated.
3974 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
3976 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
3978 Value *NewOp = Builder->CreateXor(Op0C->getOperand(0),
3979 Op1C->getOperand(0), I.getName());
3980 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
3985 return Changed ? &I : 0;
3989 Instruction *InstCombiner::visitShl(BinaryOperator &I) {
3990 return commonShiftTransforms(I);
3993 Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
3994 return commonShiftTransforms(I);
3997 Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
3998 if (Instruction *R = commonShiftTransforms(I))
4001 Value *Op0 = I.getOperand(0);
4003 // ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
4004 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
4005 if (CSI->isAllOnesValue())
4006 return ReplaceInstUsesWith(I, CSI);
4008 // See if we can turn a signed shr into an unsigned shr.
4009 if (MaskedValueIsZero(Op0,
4010 APInt::getSignBit(I.getType()->getScalarSizeInBits())))
4011 return BinaryOperator::CreateLShr(Op0, I.getOperand(1));
4013 // Arithmetic shifting an all-sign-bit value is a no-op.
4014 unsigned NumSignBits = ComputeNumSignBits(Op0);
4015 if (NumSignBits == Op0->getType()->getScalarSizeInBits())
4016 return ReplaceInstUsesWith(I, Op0);
4021 Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
4022 assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
4023 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4025 // shl X, 0 == X and shr X, 0 == X
4026 // shl 0, X == 0 and shr 0, X == 0
4027 if (Op1 == Constant::getNullValue(Op1->getType()) ||
4028 Op0 == Constant::getNullValue(Op0->getType()))
4029 return ReplaceInstUsesWith(I, Op0);
4031 if (isa<UndefValue>(Op0)) {
4032 if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
4033 return ReplaceInstUsesWith(I, Op0);
4034 else // undef << X -> 0, undef >>u X -> 0
4035 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4037 if (isa<UndefValue>(Op1)) {
4038 if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
4039 return ReplaceInstUsesWith(I, Op0);
4040 else // X << undef, X >>u undef -> 0
4041 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4044 // See if we can fold away this shift.
4045 if (SimplifyDemandedInstructionBits(I))
4048 // Try to fold constant and into select arguments.
4049 if (isa<Constant>(Op0))
4050 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
4051 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
4054 if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
4055 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
4060 Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
4061 BinaryOperator &I) {
4062 bool isLeftShift = I.getOpcode() == Instruction::Shl;
4064 // See if we can simplify any instructions used by the instruction whose sole
4065 // purpose is to compute bits we don't care about.
4066 uint32_t TypeBits = Op0->getType()->getScalarSizeInBits();
4068 // shl i32 X, 32 = 0 and srl i8 Y, 9 = 0, ... just don't eliminate
4071 if (Op1->uge(TypeBits)) {
4072 if (I.getOpcode() != Instruction::AShr)
4073 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
4075 I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
4080 // ((X*C1) << C2) == (X * (C1 << C2))
4081 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
4082 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
4083 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
4084 return BinaryOperator::CreateMul(BO->getOperand(0),
4085 ConstantExpr::getShl(BOOp, Op1));
4087 // Try to fold constant and into select arguments.
4088 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
4089 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
4091 if (isa<PHINode>(Op0))
4092 if (Instruction *NV = FoldOpIntoPhi(I))
4095 // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
4096 if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
4097 Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
4098 // If 'shift2' is an ashr, we would have to get the sign bit into a funny
4099 // place. Don't try to do this transformation in this case. Also, we
4100 // require that the input operand is a shift-by-constant so that we have
4101 // confidence that the shifts will get folded together. We could do this
4102 // xform in more cases, but it is unlikely to be profitable.
4103 if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
4104 isa<ConstantInt>(TrOp->getOperand(1))) {
4105 // Okay, we'll do this xform. Make the shift of shift.
4106 Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType());
4107 // (shift2 (shift1 & 0x00FF), c2)
4108 Value *NSh = Builder->CreateBinOp(I.getOpcode(), TrOp, ShAmt,I.getName());
4110 // For logical shifts, the truncation has the effect of making the high
4111 // part of the register be zeros. Emulate this by inserting an AND to
4112 // clear the top bits as needed. This 'and' will usually be zapped by
4113 // other xforms later if dead.
4114 unsigned SrcSize = TrOp->getType()->getScalarSizeInBits();
4115 unsigned DstSize = TI->getType()->getScalarSizeInBits();
4116 APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
4118 // The mask we constructed says what the trunc would do if occurring
4119 // between the shifts. We want to know the effect *after* the second
4120 // shift. We know that it is a logical shift by a constant, so adjust the
4121 // mask as appropriate.
4122 if (I.getOpcode() == Instruction::Shl)
4123 MaskV <<= Op1->getZExtValue();
4125 assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
4126 MaskV = MaskV.lshr(Op1->getZExtValue());
4130 Value *And = Builder->CreateAnd(NSh,
4131 ConstantInt::get(I.getContext(), MaskV),
4134 // Return the value truncated to the interesting size.
4135 return new TruncInst(And, I.getType());
4139 if (Op0->hasOneUse()) {
4140 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
4141 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
4144 switch (Op0BO->getOpcode()) {
4146 case Instruction::Add:
4147 case Instruction::And:
4148 case Instruction::Or:
4149 case Instruction::Xor: {
4150 // These operators commute.
4151 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
4152 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
4153 match(Op0BO->getOperand(1), m_Shr(m_Value(V1),
4154 m_Specific(Op1)))) {
4155 Value *YS = // (Y << C)
4156 Builder->CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
4158 Value *X = Builder->CreateBinOp(Op0BO->getOpcode(), YS, V1,
4159 Op0BO->getOperand(1)->getName());
4160 uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
4161 return BinaryOperator::CreateAnd(X, ConstantInt::get(I.getContext(),
4162 APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
4165 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
4166 Value *Op0BOOp1 = Op0BO->getOperand(1);
4167 if (isLeftShift && Op0BOOp1->hasOneUse() &&
4169 m_And(m_Shr(m_Value(V1), m_Specific(Op1)),
4170 m_ConstantInt(CC))) &&
4171 cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) {
4172 Value *YS = // (Y << C)
4173 Builder->CreateShl(Op0BO->getOperand(0), Op1,
4176 Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
4177 V1->getName()+".mask");
4178 return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
4183 case Instruction::Sub: {
4184 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
4185 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
4186 match(Op0BO->getOperand(0), m_Shr(m_Value(V1),
4187 m_Specific(Op1)))) {
4188 Value *YS = // (Y << C)
4189 Builder->CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
4191 Value *X = Builder->CreateBinOp(Op0BO->getOpcode(), V1, YS,
4192 Op0BO->getOperand(0)->getName());
4193 uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
4194 return BinaryOperator::CreateAnd(X, ConstantInt::get(I.getContext(),
4195 APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
4198 // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
4199 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
4200 match(Op0BO->getOperand(0),
4201 m_And(m_Shr(m_Value(V1), m_Value(V2)),
4202 m_ConstantInt(CC))) && V2 == Op1 &&
4203 cast<BinaryOperator>(Op0BO->getOperand(0))
4204 ->getOperand(0)->hasOneUse()) {
4205 Value *YS = // (Y << C)
4206 Builder->CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
4208 Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
4209 V1->getName()+".mask");
4211 return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
4219 // If the operand is an bitwise operator with a constant RHS, and the
4220 // shift is the only use, we can pull it out of the shift.
4221 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
4222 bool isValid = true; // Valid only for And, Or, Xor
4223 bool highBitSet = false; // Transform if high bit of constant set?
4225 switch (Op0BO->getOpcode()) {
4226 default: isValid = false; break; // Do not perform transform!
4227 case Instruction::Add:
4228 isValid = isLeftShift;
4230 case Instruction::Or:
4231 case Instruction::Xor:
4234 case Instruction::And:
4239 // If this is a signed shift right, and the high bit is modified
4240 // by the logical operation, do not perform the transformation.
4241 // The highBitSet boolean indicates the value of the high bit of
4242 // the constant which would cause it to be modified for this
4245 if (isValid && I.getOpcode() == Instruction::AShr)
4246 isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
4249 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
4252 Builder->CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1);
4253 NewShift->takeName(Op0BO);
4255 return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
4262 // Find out if this is a shift of a shift by a constant.
4263 BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
4264 if (ShiftOp && !ShiftOp->isShift())
4267 if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
4268 ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
4269 uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
4270 uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
4271 assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
4272 if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
4273 Value *X = ShiftOp->getOperand(0);
4275 uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
4277 const IntegerType *Ty = cast<IntegerType>(I.getType());
4279 // Check for (X << c1) << c2 and (X >> c1) >> c2
4280 if (I.getOpcode() == ShiftOp->getOpcode()) {
4281 // If this is oversized composite shift, then unsigned shifts get 0, ashr
4283 if (AmtSum >= TypeBits) {
4284 if (I.getOpcode() != Instruction::AShr)
4285 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4286 AmtSum = TypeBits-1; // Saturate to 31 for i32 ashr.
4289 return BinaryOperator::Create(I.getOpcode(), X,
4290 ConstantInt::get(Ty, AmtSum));
4293 if (ShiftOp->getOpcode() == Instruction::LShr &&
4294 I.getOpcode() == Instruction::AShr) {
4295 if (AmtSum >= TypeBits)
4296 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4298 // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
4299 return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
4302 if (ShiftOp->getOpcode() == Instruction::AShr &&
4303 I.getOpcode() == Instruction::LShr) {
4304 // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
4305 if (AmtSum >= TypeBits)
4306 AmtSum = TypeBits-1;
4308 Value *Shift = Builder->CreateAShr(X, ConstantInt::get(Ty, AmtSum));
4310 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
4311 return BinaryOperator::CreateAnd(Shift,
4312 ConstantInt::get(I.getContext(), Mask));
4315 // Okay, if we get here, one shift must be left, and the other shift must be
4316 // right. See if the amounts are equal.
4317 if (ShiftAmt1 == ShiftAmt2) {
4318 // If we have ((X >>? C) << C), turn this into X & (-1 << C).
4319 if (I.getOpcode() == Instruction::Shl) {
4320 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
4321 return BinaryOperator::CreateAnd(X,
4322 ConstantInt::get(I.getContext(),Mask));
4324 // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
4325 if (I.getOpcode() == Instruction::LShr) {
4326 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
4327 return BinaryOperator::CreateAnd(X,
4328 ConstantInt::get(I.getContext(), Mask));
4330 // We can simplify ((X << C) >>s C) into a trunc + sext.
4331 // NOTE: we could do this for any C, but that would make 'unusual' integer
4332 // types. For now, just stick to ones well-supported by the code
4334 const Type *SExtType = 0;
4335 switch (Ty->getBitWidth() - ShiftAmt1) {
4342 SExtType = IntegerType::get(I.getContext(),
4343 Ty->getBitWidth() - ShiftAmt1);
4348 return new SExtInst(Builder->CreateTrunc(X, SExtType, "sext"), Ty);
4349 // Otherwise, we can't handle it yet.
4350 } else if (ShiftAmt1 < ShiftAmt2) {
4351 uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
4353 // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
4354 if (I.getOpcode() == Instruction::Shl) {
4355 assert(ShiftOp->getOpcode() == Instruction::LShr ||
4356 ShiftOp->getOpcode() == Instruction::AShr);
4357 Value *Shift = Builder->CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
4359 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
4360 return BinaryOperator::CreateAnd(Shift,
4361 ConstantInt::get(I.getContext(),Mask));
4364 // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
4365 if (I.getOpcode() == Instruction::LShr) {
4366 assert(ShiftOp->getOpcode() == Instruction::Shl);
4367 Value *Shift = Builder->CreateLShr(X, ConstantInt::get(Ty, ShiftDiff));
4369 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
4370 return BinaryOperator::CreateAnd(Shift,
4371 ConstantInt::get(I.getContext(),Mask));
4374 // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
4376 assert(ShiftAmt2 < ShiftAmt1);
4377 uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
4379 // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
4380 if (I.getOpcode() == Instruction::Shl) {
4381 assert(ShiftOp->getOpcode() == Instruction::LShr ||
4382 ShiftOp->getOpcode() == Instruction::AShr);
4383 Value *Shift = Builder->CreateBinOp(ShiftOp->getOpcode(), X,
4384 ConstantInt::get(Ty, ShiftDiff));
4386 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
4387 return BinaryOperator::CreateAnd(Shift,
4388 ConstantInt::get(I.getContext(),Mask));
4391 // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
4392 if (I.getOpcode() == Instruction::LShr) {
4393 assert(ShiftOp->getOpcode() == Instruction::Shl);
4394 Value *Shift = Builder->CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
4396 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
4397 return BinaryOperator::CreateAnd(Shift,
4398 ConstantInt::get(I.getContext(),Mask));
4401 // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
4408 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
4409 /// expression. If so, decompose it, returning some value X, such that Val is
4412 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
4414 assert(Val->getType() == Type::getInt32Ty(Val->getContext()) &&
4415 "Unexpected allocation size type!");
4416 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
4417 Offset = CI->getZExtValue();
4419 return ConstantInt::get(Type::getInt32Ty(Val->getContext()), 0);
4420 } else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
4421 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
4422 if (I->getOpcode() == Instruction::Shl) {
4423 // This is a value scaled by '1 << the shift amt'.
4424 Scale = 1U << RHS->getZExtValue();
4426 return I->getOperand(0);
4427 } else if (I->getOpcode() == Instruction::Mul) {
4428 // This value is scaled by 'RHS'.
4429 Scale = RHS->getZExtValue();
4431 return I->getOperand(0);
4432 } else if (I->getOpcode() == Instruction::Add) {
4433 // We have X+C. Check to see if we really have (X*C2)+C1,
4434 // where C1 is divisible by C2.
4437 DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
4438 Offset += RHS->getZExtValue();
4445 // Otherwise, we can't look past this.
4452 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
4453 /// try to eliminate the cast by moving the type information into the alloc.
4454 Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
4456 const PointerType *PTy = cast<PointerType>(CI.getType());
4458 BuilderTy AllocaBuilder(*Builder);
4459 AllocaBuilder.SetInsertPoint(AI.getParent(), &AI);
4461 // Remove any uses of AI that are dead.
4462 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
4464 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
4465 Instruction *User = cast<Instruction>(*UI++);
4466 if (isInstructionTriviallyDead(User)) {
4467 while (UI != E && *UI == User)
4468 ++UI; // If this instruction uses AI more than once, don't break UI.
4471 DEBUG(errs() << "IC: DCE: " << *User << '\n');
4472 EraseInstFromFunction(*User);
4476 // This requires TargetData to get the alloca alignment and size information.
4479 // Get the type really allocated and the type casted to.
4480 const Type *AllocElTy = AI.getAllocatedType();
4481 const Type *CastElTy = PTy->getElementType();
4482 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
4484 unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
4485 unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
4486 if (CastElTyAlign < AllocElTyAlign) return 0;
4488 // If the allocation has multiple uses, only promote it if we are strictly
4489 // increasing the alignment of the resultant allocation. If we keep it the
4490 // same, we open the door to infinite loops of various kinds. (A reference
4491 // from a dbg.declare doesn't count as a use for this purpose.)
4492 if (!AI.hasOneUse() && !hasOneUsePlusDeclare(&AI) &&
4493 CastElTyAlign == AllocElTyAlign) return 0;
4495 uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy);
4496 uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy);
4497 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
4499 // See if we can satisfy the modulus by pulling a scale out of the array
4501 unsigned ArraySizeScale;
4503 Value *NumElements = // See if the array size is a decomposable linear expr.
4504 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
4506 // If we can now satisfy the modulus, by using a non-1 scale, we really can
4508 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
4509 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
4511 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
4516 Amt = ConstantInt::get(Type::getInt32Ty(CI.getContext()), Scale);
4517 // Insert before the alloca, not before the cast.
4518 Amt = AllocaBuilder.CreateMul(Amt, NumElements, "tmp");
4521 if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
4522 Value *Off = ConstantInt::get(Type::getInt32Ty(CI.getContext()),
4524 Amt = AllocaBuilder.CreateAdd(Amt, Off, "tmp");
4527 AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
4528 New->setAlignment(AI.getAlignment());
4531 // If the allocation has one real use plus a dbg.declare, just remove the
4533 if (DbgDeclareInst *DI = hasOneUsePlusDeclare(&AI)) {
4534 EraseInstFromFunction(*DI);
4536 // If the allocation has multiple real uses, insert a cast and change all
4537 // things that used it to use the new cast. This will also hack on CI, but it
4539 else if (!AI.hasOneUse()) {
4540 // New is the allocation instruction, pointer typed. AI is the original
4541 // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
4542 Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
4543 AI.replaceAllUsesWith(NewCast);
4545 return ReplaceInstUsesWith(CI, New);
4548 /// CanEvaluateInDifferentType - Return true if we can take the specified value
4549 /// and return it as type Ty without inserting any new casts and without
4550 /// changing the computed value. This is used by code that tries to decide
4551 /// whether promoting or shrinking integer operations to wider or smaller types
4552 /// will allow us to eliminate a truncate or extend.
4554 /// This is a truncation operation if Ty is smaller than V->getType(), or an
4555 /// extension operation if Ty is larger.
4557 /// If CastOpc is a truncation, then Ty will be a type smaller than V. We
4558 /// should return true if trunc(V) can be computed by computing V in the smaller
4559 /// type. If V is an instruction, then trunc(inst(x,y)) can be computed as
4560 /// inst(trunc(x),trunc(y)), which only makes sense if x and y can be
4561 /// efficiently truncated.
4563 /// If CastOpc is a sext or zext, we are asking if the low bits of the value can
4564 /// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
4565 /// the final result.
4566 bool InstCombiner::CanEvaluateInDifferentType(Value *V, const Type *Ty,
4568 int &NumCastsRemoved){
4569 // We can always evaluate constants in another type.
4570 if (isa<Constant>(V))
4573 Instruction *I = dyn_cast<Instruction>(V);
4574 if (!I) return false;
4576 const Type *OrigTy = V->getType();
4578 // If this is an extension or truncate, we can often eliminate it.
4579 if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
4580 // If this is a cast from the destination type, we can trivially eliminate
4581 // it, and this will remove a cast overall.
4582 if (I->getOperand(0)->getType() == Ty) {
4583 // If the first operand is itself a cast, and is eliminable, do not count
4584 // this as an eliminable cast. We would prefer to eliminate those two
4586 if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
4592 // We can't extend or shrink something that has multiple uses: doing so would
4593 // require duplicating the instruction in general, which isn't profitable.
4594 if (!I->hasOneUse()) return false;
4596 unsigned Opc = I->getOpcode();
4598 case Instruction::Add:
4599 case Instruction::Sub:
4600 case Instruction::Mul:
4601 case Instruction::And:
4602 case Instruction::Or:
4603 case Instruction::Xor:
4604 // These operators can all arbitrarily be extended or truncated.
4605 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
4607 CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
4610 case Instruction::UDiv:
4611 case Instruction::URem: {
4612 // UDiv and URem can be truncated if all the truncated bits are zero.
4613 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
4614 uint32_t BitWidth = Ty->getScalarSizeInBits();
4615 if (BitWidth < OrigBitWidth) {
4616 APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
4617 if (MaskedValueIsZero(I->getOperand(0), Mask) &&
4618 MaskedValueIsZero(I->getOperand(1), Mask)) {
4619 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
4621 CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
4627 case Instruction::Shl:
4628 // If we are truncating the result of this SHL, and if it's a shift of a
4629 // constant amount, we can always perform a SHL in a smaller type.
4630 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
4631 uint32_t BitWidth = Ty->getScalarSizeInBits();
4632 if (BitWidth < OrigTy->getScalarSizeInBits() &&
4633 CI->getLimitedValue(BitWidth) < BitWidth)
4634 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
4638 case Instruction::LShr:
4639 // If this is a truncate of a logical shr, we can truncate it to a smaller
4640 // lshr iff we know that the bits we would otherwise be shifting in are
4642 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
4643 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
4644 uint32_t BitWidth = Ty->getScalarSizeInBits();
4645 if (BitWidth < OrigBitWidth &&
4646 MaskedValueIsZero(I->getOperand(0),
4647 APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
4648 CI->getLimitedValue(BitWidth) < BitWidth) {
4649 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
4654 case Instruction::ZExt:
4655 case Instruction::SExt:
4656 case Instruction::Trunc:
4657 // If this is the same kind of case as our original (e.g. zext+zext), we
4658 // can safely replace it. Note that replacing it does not reduce the number
4659 // of casts in the input.
4663 // sext (zext ty1), ty2 -> zext ty2
4664 if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt)
4667 case Instruction::Select: {
4668 SelectInst *SI = cast<SelectInst>(I);
4669 return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
4671 CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
4674 case Instruction::PHI: {
4675 // We can change a phi if we can change all operands.
4676 PHINode *PN = cast<PHINode>(I);
4677 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
4678 if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
4684 // TODO: Can handle more cases here.
4691 /// EvaluateInDifferentType - Given an expression that
4692 /// CanEvaluateInDifferentType returns true for, actually insert the code to
4693 /// evaluate the expression.
4694 Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
4696 if (Constant *C = dyn_cast<Constant>(V))
4697 return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
4699 // Otherwise, it must be an instruction.
4700 Instruction *I = cast<Instruction>(V);
4701 Instruction *Res = 0;
4702 unsigned Opc = I->getOpcode();
4704 case Instruction::Add:
4705 case Instruction::Sub:
4706 case Instruction::Mul:
4707 case Instruction::And:
4708 case Instruction::Or:
4709 case Instruction::Xor:
4710 case Instruction::AShr:
4711 case Instruction::LShr:
4712 case Instruction::Shl:
4713 case Instruction::UDiv:
4714 case Instruction::URem: {
4715 Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
4716 Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
4717 Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
4720 case Instruction::Trunc:
4721 case Instruction::ZExt:
4722 case Instruction::SExt:
4723 // If the source type of the cast is the type we're trying for then we can
4724 // just return the source. There's no need to insert it because it is not
4726 if (I->getOperand(0)->getType() == Ty)
4727 return I->getOperand(0);
4729 // Otherwise, must be the same type of cast, so just reinsert a new one.
4730 Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty);
4732 case Instruction::Select: {
4733 Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
4734 Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
4735 Res = SelectInst::Create(I->getOperand(0), True, False);
4738 case Instruction::PHI: {
4739 PHINode *OPN = cast<PHINode>(I);
4740 PHINode *NPN = PHINode::Create(Ty);
4741 for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
4742 Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
4743 NPN->addIncoming(V, OPN->getIncomingBlock(i));
4749 // TODO: Can handle more cases here.
4750 llvm_unreachable("Unreachable!");
4755 return InsertNewInstBefore(Res, *I);
4758 /// @brief Implement the transforms common to all CastInst visitors.
4759 Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
4760 Value *Src = CI.getOperand(0);
4762 // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
4763 // eliminate it now.
4764 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
4765 if (Instruction::CastOps opc =
4766 isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
4767 // The first cast (CSrc) is eliminable so we need to fix up or replace
4768 // the second cast (CI). CSrc will then have a good chance of being dead.
4769 return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
4773 // If we are casting a select then fold the cast into the select
4774 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
4775 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
4778 // If we are casting a PHI then fold the cast into the PHI
4779 if (isa<PHINode>(Src)) {
4780 // We don't do this if this would create a PHI node with an illegal type if
4781 // it is currently legal.
4782 if (!isa<IntegerType>(Src->getType()) ||
4783 !isa<IntegerType>(CI.getType()) ||
4784 ShouldChangeType(CI.getType(), Src->getType(), TD))
4785 if (Instruction *NV = FoldOpIntoPhi(CI))
4792 /// FindElementAtOffset - Given a type and a constant offset, determine whether
4793 /// or not there is a sequence of GEP indices into the type that will land us at
4794 /// the specified offset. If so, fill them into NewIndices and return the
4795 /// resultant element type, otherwise return null.
4796 static const Type *FindElementAtOffset(const Type *Ty, int64_t Offset,
4797 SmallVectorImpl<Value*> &NewIndices,
4798 const TargetData *TD) {
4800 if (!Ty->isSized()) return 0;
4802 // Start with the index over the outer type. Note that the type size
4803 // might be zero (even if the offset isn't zero) if the indexed type
4804 // is something like [0 x {int, int}]
4805 const Type *IntPtrTy = TD->getIntPtrType(Ty->getContext());
4806 int64_t FirstIdx = 0;
4807 if (int64_t TySize = TD->getTypeAllocSize(Ty)) {
4808 FirstIdx = Offset/TySize;
4809 Offset -= FirstIdx*TySize;
4811 // Handle hosts where % returns negative instead of values [0..TySize).
4815 assert(Offset >= 0);
4817 assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset");
4820 NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
4822 // Index into the types. If we fail, set OrigBase to null.
4824 // Indexing into tail padding between struct/array elements.
4825 if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty))
4828 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
4829 const StructLayout *SL = TD->getStructLayout(STy);
4830 assert(Offset < (int64_t)SL->getSizeInBytes() &&
4831 "Offset must stay within the indexed type");
4833 unsigned Elt = SL->getElementContainingOffset(Offset);
4834 NewIndices.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
4837 Offset -= SL->getElementOffset(Elt);
4838 Ty = STy->getElementType(Elt);
4839 } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
4840 uint64_t EltSize = TD->getTypeAllocSize(AT->getElementType());
4841 assert(EltSize && "Cannot index into a zero-sized array");
4842 NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
4844 Ty = AT->getElementType();
4846 // Otherwise, we can't index into the middle of this atomic type, bail.
4854 /// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
4855 Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
4856 Value *Src = CI.getOperand(0);
4858 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
4859 // If casting the result of a getelementptr instruction with no offset, turn
4860 // this into a cast of the original pointer!
4861 if (GEP->hasAllZeroIndices()) {
4862 // Changing the cast operand is usually not a good idea but it is safe
4863 // here because the pointer operand is being replaced with another
4864 // pointer operand so the opcode doesn't need to change.
4866 CI.setOperand(0, GEP->getOperand(0));
4870 // If the GEP has a single use, and the base pointer is a bitcast, and the
4871 // GEP computes a constant offset, see if we can convert these three
4872 // instructions into fewer. This typically happens with unions and other
4873 // non-type-safe code.
4874 if (TD && GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
4875 if (GEP->hasAllConstantIndices()) {
4876 // We are guaranteed to get a constant from EmitGEPOffset.
4877 ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP));
4878 int64_t Offset = OffsetV->getSExtValue();
4880 // Get the base pointer input of the bitcast, and the type it points to.
4881 Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
4882 const Type *GEPIdxTy =
4883 cast<PointerType>(OrigBase->getType())->getElementType();
4884 SmallVector<Value*, 8> NewIndices;
4885 if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices, TD)) {
4886 // If we were able to index down into an element, create the GEP
4887 // and bitcast the result. This eliminates one bitcast, potentially
4889 Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?
4890 Builder->CreateInBoundsGEP(OrigBase,
4891 NewIndices.begin(), NewIndices.end()) :
4892 Builder->CreateGEP(OrigBase, NewIndices.begin(), NewIndices.end());
4893 NGEP->takeName(GEP);
4895 if (isa<BitCastInst>(CI))
4896 return new BitCastInst(NGEP, CI.getType());
4897 assert(isa<PtrToIntInst>(CI));
4898 return new PtrToIntInst(NGEP, CI.getType());
4904 return commonCastTransforms(CI);
4907 /// commonIntCastTransforms - This function implements the common transforms
4908 /// for trunc, zext, and sext.
4909 Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
4910 if (Instruction *Result = commonCastTransforms(CI))
4913 Value *Src = CI.getOperand(0);
4914 const Type *SrcTy = Src->getType();
4915 const Type *DestTy = CI.getType();
4916 uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
4917 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
4919 // See if we can simplify any instructions used by the LHS whose sole
4920 // purpose is to compute bits we don't care about.
4921 if (SimplifyDemandedInstructionBits(CI))
4924 // If the source isn't an instruction or has more than one use then we
4925 // can't do anything more.
4926 Instruction *SrcI = dyn_cast<Instruction>(Src);
4927 if (!SrcI || !Src->hasOneUse())
4930 // Attempt to propagate the cast into the instruction for int->int casts.
4931 int NumCastsRemoved = 0;
4932 // Only do this if the dest type is a simple type, don't convert the
4933 // expression tree to something weird like i93 unless the source is also
4935 if ((isa<VectorType>(DestTy) ||
4936 ShouldChangeType(SrcI->getType(), DestTy, TD)) &&
4937 CanEvaluateInDifferentType(SrcI, DestTy,
4938 CI.getOpcode(), NumCastsRemoved)) {
4939 // If this cast is a truncate, evaluting in a different type always
4940 // eliminates the cast, so it is always a win. If this is a zero-extension,
4941 // we need to do an AND to maintain the clear top-part of the computation,
4942 // so we require that the input have eliminated at least one cast. If this
4943 // is a sign extension, we insert two new casts (to do the extension) so we
4944 // require that two casts have been eliminated.
4945 bool DoXForm = false;
4946 bool JustReplace = false;
4947 switch (CI.getOpcode()) {
4949 // All the others use floating point so we shouldn't actually
4950 // get here because of the check above.
4951 llvm_unreachable("Unknown cast type");
4952 case Instruction::Trunc:
4955 case Instruction::ZExt: {
4956 DoXForm = NumCastsRemoved >= 1;
4958 if (!DoXForm && 0) {
4959 // If it's unnecessary to issue an AND to clear the high bits, it's
4960 // always profitable to do this xform.
4961 Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, false);
4962 APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
4963 if (MaskedValueIsZero(TryRes, Mask))
4964 return ReplaceInstUsesWith(CI, TryRes);
4966 if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
4967 if (TryI->use_empty())
4968 EraseInstFromFunction(*TryI);
4972 case Instruction::SExt: {
4973 DoXForm = NumCastsRemoved >= 2;
4974 if (!DoXForm && !isa<TruncInst>(SrcI) && 0) {
4975 // If we do not have to emit the truncate + sext pair, then it's always
4976 // profitable to do this xform.
4978 // It's not safe to eliminate the trunc + sext pair if one of the
4979 // eliminated cast is a truncate. e.g.
4980 // t2 = trunc i32 t1 to i16
4981 // t3 = sext i16 t2 to i32
4984 Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, true);
4985 unsigned NumSignBits = ComputeNumSignBits(TryRes);
4986 if (NumSignBits > (DestBitSize - SrcBitSize))
4987 return ReplaceInstUsesWith(CI, TryRes);
4989 if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
4990 if (TryI->use_empty())
4991 EraseInstFromFunction(*TryI);
4998 DEBUG(errs() << "ICE: EvaluateInDifferentType converting expression type"
4999 " to avoid cast: " << CI);
5000 Value *Res = EvaluateInDifferentType(SrcI, DestTy,
5001 CI.getOpcode() == Instruction::SExt);
5003 // Just replace this cast with the result.
5004 return ReplaceInstUsesWith(CI, Res);
5006 assert(Res->getType() == DestTy);
5007 switch (CI.getOpcode()) {
5008 default: llvm_unreachable("Unknown cast type!");
5009 case Instruction::Trunc:
5010 // Just replace this cast with the result.
5011 return ReplaceInstUsesWith(CI, Res);
5012 case Instruction::ZExt: {
5013 assert(SrcBitSize < DestBitSize && "Not a zext?");
5015 // If the high bits are already zero, just replace this cast with the
5017 APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
5018 if (MaskedValueIsZero(Res, Mask))
5019 return ReplaceInstUsesWith(CI, Res);
5021 // We need to emit an AND to clear the high bits.
5022 Constant *C = ConstantInt::get(CI.getContext(),
5023 APInt::getLowBitsSet(DestBitSize, SrcBitSize));
5024 return BinaryOperator::CreateAnd(Res, C);
5026 case Instruction::SExt: {
5027 // If the high bits are already filled with sign bit, just replace this
5028 // cast with the result.
5029 unsigned NumSignBits = ComputeNumSignBits(Res);
5030 if (NumSignBits > (DestBitSize - SrcBitSize))
5031 return ReplaceInstUsesWith(CI, Res);
5033 // We need to emit a cast to truncate, then a cast to sext.
5034 return new SExtInst(Builder->CreateTrunc(Res, Src->getType()), DestTy);
5040 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
5041 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
5043 switch (SrcI->getOpcode()) {
5044 case Instruction::Add:
5045 case Instruction::Mul:
5046 case Instruction::And:
5047 case Instruction::Or:
5048 case Instruction::Xor:
5049 // If we are discarding information, rewrite.
5050 if (DestBitSize < SrcBitSize && DestBitSize != 1) {
5051 // Don't insert two casts unless at least one can be eliminated.
5052 if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
5053 !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
5054 Value *Op0c = Builder->CreateTrunc(Op0, DestTy, Op0->getName());
5055 Value *Op1c = Builder->CreateTrunc(Op1, DestTy, Op1->getName());
5056 return BinaryOperator::Create(
5057 cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
5061 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
5062 if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
5063 SrcI->getOpcode() == Instruction::Xor &&
5064 Op1 == ConstantInt::getTrue(CI.getContext()) &&
5065 (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
5066 Value *New = Builder->CreateZExt(Op0, DestTy, Op0->getName());
5067 return BinaryOperator::CreateXor(New,
5068 ConstantInt::get(CI.getType(), 1));
5072 case Instruction::Shl: {
5073 // Canonicalize trunc inside shl, if we can.
5074 ConstantInt *CI = dyn_cast<ConstantInt>(Op1);
5075 if (CI && DestBitSize < SrcBitSize &&
5076 CI->getLimitedValue(DestBitSize) < DestBitSize) {
5077 Value *Op0c = Builder->CreateTrunc(Op0, DestTy, Op0->getName());
5078 Value *Op1c = Builder->CreateTrunc(Op1, DestTy, Op1->getName());
5079 return BinaryOperator::CreateShl(Op0c, Op1c);
5087 Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
5088 if (Instruction *Result = commonIntCastTransforms(CI))
5091 Value *Src = CI.getOperand(0);
5092 const Type *Ty = CI.getType();
5093 uint32_t DestBitWidth = Ty->getScalarSizeInBits();
5094 uint32_t SrcBitWidth = Src->getType()->getScalarSizeInBits();
5096 // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0)
5097 if (DestBitWidth == 1) {
5098 Constant *One = ConstantInt::get(Src->getType(), 1);
5099 Src = Builder->CreateAnd(Src, One, "tmp");
5100 Value *Zero = Constant::getNullValue(Src->getType());
5101 return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
5104 // Optimize trunc(lshr(), c) to pull the shift through the truncate.
5105 ConstantInt *ShAmtV = 0;
5107 if (Src->hasOneUse() &&
5108 match(Src, m_LShr(m_Value(ShiftOp), m_ConstantInt(ShAmtV)))) {
5109 uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
5111 // Get a mask for the bits shifting in.
5112 APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
5113 if (MaskedValueIsZero(ShiftOp, Mask)) {
5114 if (ShAmt >= DestBitWidth) // All zeros.
5115 return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
5117 // Okay, we can shrink this. Truncate the input, then return a new
5119 Value *V1 = Builder->CreateTrunc(ShiftOp, Ty, ShiftOp->getName());
5120 Value *V2 = ConstantExpr::getTrunc(ShAmtV, Ty);
5121 return BinaryOperator::CreateLShr(V1, V2);
5128 /// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
5129 /// in order to eliminate the icmp.
5130 Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
5132 // If we are just checking for a icmp eq of a single bit and zext'ing it
5133 // to an integer, then shift the bit to the appropriate place and then
5134 // cast to integer to avoid the comparison.
5135 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
5136 const APInt &Op1CV = Op1C->getValue();
5138 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
5139 // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
5140 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
5141 (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
5142 if (!DoXform) return ICI;
5144 Value *In = ICI->getOperand(0);
5145 Value *Sh = ConstantInt::get(In->getType(),
5146 In->getType()->getScalarSizeInBits()-1);
5147 In = Builder->CreateLShr(In, Sh, In->getName()+".lobit");
5148 if (In->getType() != CI.getType())
5149 In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/, "tmp");
5151 if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
5152 Constant *One = ConstantInt::get(In->getType(), 1);
5153 In = Builder->CreateXor(In, One, In->getName()+".not");
5156 return ReplaceInstUsesWith(CI, In);
5161 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
5162 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
5163 // zext (X == 1) to i32 --> X iff X has only the low bit set.
5164 // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
5165 // zext (X != 0) to i32 --> X iff X has only the low bit set.
5166 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
5167 // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
5168 // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
5169 if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
5170 // This only works for EQ and NE
5171 ICI->isEquality()) {
5172 // If Op1C some other power of two, convert:
5173 uint32_t BitWidth = Op1C->getType()->getBitWidth();
5174 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
5175 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
5176 ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
5178 APInt KnownZeroMask(~KnownZero);
5179 if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
5180 if (!DoXform) return ICI;
5182 bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
5183 if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
5184 // (X&4) == 2 --> false
5185 // (X&4) != 2 --> true
5186 Constant *Res = ConstantInt::get(Type::getInt1Ty(CI.getContext()),
5188 Res = ConstantExpr::getZExt(Res, CI.getType());
5189 return ReplaceInstUsesWith(CI, Res);
5192 uint32_t ShiftAmt = KnownZeroMask.logBase2();
5193 Value *In = ICI->getOperand(0);
5195 // Perform a logical shr by shiftamt.
5196 // Insert the shift to put the result in the low bit.
5197 In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt),
5198 In->getName()+".lobit");
5201 if ((Op1CV != 0) == isNE) { // Toggle the low bit.
5202 Constant *One = ConstantInt::get(In->getType(), 1);
5203 In = Builder->CreateXor(In, One, "tmp");
5206 if (CI.getType() == In->getType())
5207 return ReplaceInstUsesWith(CI, In);
5209 return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
5214 // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
5215 // It is also profitable to transform icmp eq into not(xor(A, B)) because that
5216 // may lead to additional simplifications.
5217 if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
5218 if (const IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
5219 uint32_t BitWidth = ITy->getBitWidth();
5220 Value *LHS = ICI->getOperand(0);
5221 Value *RHS = ICI->getOperand(1);
5223 APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0);
5224 APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0);
5225 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
5226 ComputeMaskedBits(LHS, TypeMask, KnownZeroLHS, KnownOneLHS);
5227 ComputeMaskedBits(RHS, TypeMask, KnownZeroRHS, KnownOneRHS);
5229 if (KnownZeroLHS == KnownZeroRHS && KnownOneLHS == KnownOneRHS) {
5230 APInt KnownBits = KnownZeroLHS | KnownOneLHS;
5231 APInt UnknownBit = ~KnownBits;
5232 if (UnknownBit.countPopulation() == 1) {
5233 if (!DoXform) return ICI;
5235 Value *Result = Builder->CreateXor(LHS, RHS);
5237 // Mask off any bits that are set and won't be shifted away.
5238 if (KnownOneLHS.uge(UnknownBit))
5239 Result = Builder->CreateAnd(Result,
5240 ConstantInt::get(ITy, UnknownBit));
5242 // Shift the bit we're testing down to the lsb.
5243 Result = Builder->CreateLShr(
5244 Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
5246 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
5247 Result = Builder->CreateXor(Result, ConstantInt::get(ITy, 1));
5248 Result->takeName(ICI);
5249 return ReplaceInstUsesWith(CI, Result);
5258 Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
5259 // If one of the common conversion will work, do it.
5260 if (Instruction *Result = commonIntCastTransforms(CI))
5263 Value *Src = CI.getOperand(0);
5265 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
5266 // types and if the sizes are just right we can convert this into a logical
5267 // 'and' which will be much cheaper than the pair of casts.
5268 if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
5269 // Get the sizes of the types involved. We know that the intermediate type
5270 // will be smaller than A or C, but don't know the relation between A and C.
5271 Value *A = CSrc->getOperand(0);
5272 unsigned SrcSize = A->getType()->getScalarSizeInBits();
5273 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
5274 unsigned DstSize = CI.getType()->getScalarSizeInBits();
5275 // If we're actually extending zero bits, then if
5276 // SrcSize < DstSize: zext(a & mask)
5277 // SrcSize == DstSize: a & mask
5278 // SrcSize > DstSize: trunc(a) & mask
5279 if (SrcSize < DstSize) {
5280 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
5281 Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
5282 Value *And = Builder->CreateAnd(A, AndConst, CSrc->getName()+".mask");
5283 return new ZExtInst(And, CI.getType());
5286 if (SrcSize == DstSize) {
5287 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
5288 return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
5291 if (SrcSize > DstSize) {
5292 Value *Trunc = Builder->CreateTrunc(A, CI.getType(), "tmp");
5293 APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
5294 return BinaryOperator::CreateAnd(Trunc,
5295 ConstantInt::get(Trunc->getType(),
5300 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
5301 return transformZExtICmp(ICI, CI);
5303 BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
5304 if (SrcI && SrcI->getOpcode() == Instruction::Or) {
5305 // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
5306 // of the (zext icmp) will be transformed.
5307 ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
5308 ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
5309 if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
5310 (transformZExtICmp(LHS, CI, false) ||
5311 transformZExtICmp(RHS, CI, false))) {
5312 Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName());
5313 Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName());
5314 return BinaryOperator::Create(Instruction::Or, LCast, RCast);
5318 // zext(trunc(t) & C) -> (t & zext(C)).
5319 if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse())
5320 if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
5321 if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) {
5322 Value *TI0 = TI->getOperand(0);
5323 if (TI0->getType() == CI.getType())
5325 BinaryOperator::CreateAnd(TI0,
5326 ConstantExpr::getZExt(C, CI.getType()));
5329 // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)).
5330 if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse())
5331 if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
5332 if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0)))
5333 if (And->getOpcode() == Instruction::And && And->hasOneUse() &&
5334 And->getOperand(1) == C)
5335 if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) {
5336 Value *TI0 = TI->getOperand(0);
5337 if (TI0->getType() == CI.getType()) {
5338 Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
5339 Value *NewAnd = Builder->CreateAnd(TI0, ZC, "tmp");
5340 return BinaryOperator::CreateXor(NewAnd, ZC);
5347 Instruction *InstCombiner::visitSExt(SExtInst &CI) {
5348 if (Instruction *I = commonIntCastTransforms(CI))
5351 Value *Src = CI.getOperand(0);
5353 // Canonicalize sign-extend from i1 to a select.
5354 if (Src->getType() == Type::getInt1Ty(CI.getContext()))
5355 return SelectInst::Create(Src,
5356 Constant::getAllOnesValue(CI.getType()),
5357 Constant::getNullValue(CI.getType()));
5359 // See if the value being truncated is already sign extended. If so, just
5360 // eliminate the trunc/sext pair.
5361 if (Operator::getOpcode(Src) == Instruction::Trunc) {
5362 Value *Op = cast<User>(Src)->getOperand(0);
5363 unsigned OpBits = Op->getType()->getScalarSizeInBits();
5364 unsigned MidBits = Src->getType()->getScalarSizeInBits();
5365 unsigned DestBits = CI.getType()->getScalarSizeInBits();
5366 unsigned NumSignBits = ComputeNumSignBits(Op);
5368 if (OpBits == DestBits) {
5369 // Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign
5370 // bits, it is already ready.
5371 if (NumSignBits > DestBits-MidBits)
5372 return ReplaceInstUsesWith(CI, Op);
5373 } else if (OpBits < DestBits) {
5374 // Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign
5375 // bits, just sext from i32.
5376 if (NumSignBits > OpBits-MidBits)
5377 return new SExtInst(Op, CI.getType(), "tmp");
5379 // Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign
5380 // bits, just truncate to i32.
5381 if (NumSignBits > OpBits-MidBits)
5382 return new TruncInst(Op, CI.getType(), "tmp");
5386 // If the input is a shl/ashr pair of a same constant, then this is a sign
5387 // extension from a smaller value. If we could trust arbitrary bitwidth
5388 // integers, we could turn this into a truncate to the smaller bit and then
5389 // use a sext for the whole extension. Since we don't, look deeper and check
5390 // for a truncate. If the source and dest are the same type, eliminate the
5391 // trunc and extend and just do shifts. For example, turn:
5392 // %a = trunc i32 %i to i8
5393 // %b = shl i8 %a, 6
5394 // %c = ashr i8 %b, 6
5395 // %d = sext i8 %c to i32
5397 // %a = shl i32 %i, 30
5398 // %d = ashr i32 %a, 30
5400 ConstantInt *BA = 0, *CA = 0;
5401 if (match(Src, m_AShr(m_Shl(m_Value(A), m_ConstantInt(BA)),
5402 m_ConstantInt(CA))) &&
5403 BA == CA && isa<TruncInst>(A)) {
5404 Value *I = cast<TruncInst>(A)->getOperand(0);
5405 if (I->getType() == CI.getType()) {
5406 unsigned MidSize = Src->getType()->getScalarSizeInBits();
5407 unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
5408 unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
5409 Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
5410 I = Builder->CreateShl(I, ShAmtV, CI.getName());
5411 return BinaryOperator::CreateAShr(I, ShAmtV);
5418 /// FitsInFPType - Return a Constant* for the specified FP constant if it fits
5419 /// in the specified FP type without changing its value.
5420 static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
5422 APFloat F = CFP->getValueAPF();
5423 (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
5425 return ConstantFP::get(CFP->getContext(), F);
5429 /// LookThroughFPExtensions - If this is an fp extension instruction, look
5430 /// through it until we get the source value.
5431 static Value *LookThroughFPExtensions(Value *V) {
5432 if (Instruction *I = dyn_cast<Instruction>(V))
5433 if (I->getOpcode() == Instruction::FPExt)
5434 return LookThroughFPExtensions(I->getOperand(0));
5436 // If this value is a constant, return the constant in the smallest FP type
5437 // that can accurately represent it. This allows us to turn
5438 // (float)((double)X+2.0) into x+2.0f.
5439 if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
5440 if (CFP->getType() == Type::getPPC_FP128Ty(V->getContext()))
5441 return V; // No constant folding of this.
5442 // See if the value can be truncated to float and then reextended.
5443 if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle))
5445 if (CFP->getType() == Type::getDoubleTy(V->getContext()))
5446 return V; // Won't shrink.
5447 if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble))
5449 // Don't try to shrink to various long double types.
5455 Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
5456 if (Instruction *I = commonCastTransforms(CI))
5459 // If we have fptrunc(fadd (fpextend x), (fpextend y)), where x and y are
5460 // smaller than the destination type, we can eliminate the truncate by doing
5461 // the add as the smaller type. This applies to fadd/fsub/fmul/fdiv as well as
5462 // many builtins (sqrt, etc).
5463 BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
5464 if (OpI && OpI->hasOneUse()) {
5465 switch (OpI->getOpcode()) {
5467 case Instruction::FAdd:
5468 case Instruction::FSub:
5469 case Instruction::FMul:
5470 case Instruction::FDiv:
5471 case Instruction::FRem:
5472 const Type *SrcTy = OpI->getType();
5473 Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0));
5474 Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1));
5475 if (LHSTrunc->getType() != SrcTy &&
5476 RHSTrunc->getType() != SrcTy) {
5477 unsigned DstSize = CI.getType()->getScalarSizeInBits();
5478 // If the source types were both smaller than the destination type of
5479 // the cast, do this xform.
5480 if (LHSTrunc->getType()->getScalarSizeInBits() <= DstSize &&
5481 RHSTrunc->getType()->getScalarSizeInBits() <= DstSize) {
5482 LHSTrunc = Builder->CreateFPExt(LHSTrunc, CI.getType());
5483 RHSTrunc = Builder->CreateFPExt(RHSTrunc, CI.getType());
5484 return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc);
5493 Instruction *InstCombiner::visitFPExt(CastInst &CI) {
5494 return commonCastTransforms(CI);
5497 Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
5498 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
5500 return commonCastTransforms(FI);
5502 // fptoui(uitofp(X)) --> X
5503 // fptoui(sitofp(X)) --> X
5504 // This is safe if the intermediate type has enough bits in its mantissa to
5505 // accurately represent all values of X. For example, do not do this with
5506 // i64->float->i64. This is also safe for sitofp case, because any negative
5507 // 'X' value would cause an undefined result for the fptoui.
5508 if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
5509 OpI->getOperand(0)->getType() == FI.getType() &&
5510 (int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */
5511 OpI->getType()->getFPMantissaWidth())
5512 return ReplaceInstUsesWith(FI, OpI->getOperand(0));
5514 return commonCastTransforms(FI);
5517 Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
5518 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
5520 return commonCastTransforms(FI);
5522 // fptosi(sitofp(X)) --> X
5523 // fptosi(uitofp(X)) --> X
5524 // This is safe if the intermediate type has enough bits in its mantissa to
5525 // accurately represent all values of X. For example, do not do this with
5526 // i64->float->i64. This is also safe for sitofp case, because any negative
5527 // 'X' value would cause an undefined result for the fptoui.
5528 if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
5529 OpI->getOperand(0)->getType() == FI.getType() &&
5530 (int)FI.getType()->getScalarSizeInBits() <=
5531 OpI->getType()->getFPMantissaWidth())
5532 return ReplaceInstUsesWith(FI, OpI->getOperand(0));
5534 return commonCastTransforms(FI);
5537 Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
5538 return commonCastTransforms(CI);
5541 Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
5542 return commonCastTransforms(CI);
5545 Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
5546 // If the destination integer type is smaller than the intptr_t type for
5547 // this target, do a ptrtoint to intptr_t then do a trunc. This allows the
5548 // trunc to be exposed to other transforms. Don't do this for extending
5549 // ptrtoint's, because we don't know if the target sign or zero extends its
5552 CI.getType()->getScalarSizeInBits() < TD->getPointerSizeInBits()) {
5553 Value *P = Builder->CreatePtrToInt(CI.getOperand(0),
5554 TD->getIntPtrType(CI.getContext()),
5556 return new TruncInst(P, CI.getType());
5559 return commonPointerCastTransforms(CI);
5562 Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
5563 // If the source integer type is larger than the intptr_t type for
5564 // this target, do a trunc to the intptr_t type, then inttoptr of it. This
5565 // allows the trunc to be exposed to other transforms. Don't do this for
5566 // extending inttoptr's, because we don't know if the target sign or zero
5567 // extends to pointers.
5568 if (TD && CI.getOperand(0)->getType()->getScalarSizeInBits() >
5569 TD->getPointerSizeInBits()) {
5570 Value *P = Builder->CreateTrunc(CI.getOperand(0),
5571 TD->getIntPtrType(CI.getContext()), "tmp");
5572 return new IntToPtrInst(P, CI.getType());
5575 if (Instruction *I = commonCastTransforms(CI))
5581 Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
5582 // If the operands are integer typed then apply the integer transforms,
5583 // otherwise just apply the common ones.
5584 Value *Src = CI.getOperand(0);
5585 const Type *SrcTy = Src->getType();
5586 const Type *DestTy = CI.getType();
5588 if (isa<PointerType>(SrcTy)) {
5589 if (Instruction *I = commonPointerCastTransforms(CI))
5592 if (Instruction *Result = commonCastTransforms(CI))
5597 // Get rid of casts from one type to the same type. These are useless and can
5598 // be replaced by the operand.
5599 if (DestTy == Src->getType())
5600 return ReplaceInstUsesWith(CI, Src);
5602 if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
5603 const PointerType *SrcPTy = cast<PointerType>(SrcTy);
5604 const Type *DstElTy = DstPTy->getElementType();
5605 const Type *SrcElTy = SrcPTy->getElementType();
5607 // If the address spaces don't match, don't eliminate the bitcast, which is
5608 // required for changing types.
5609 if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
5612 // If we are casting a alloca to a pointer to a type of the same
5613 // size, rewrite the allocation instruction to allocate the "right" type.
5614 // There is no need to modify malloc calls because it is their bitcast that
5615 // needs to be cleaned up.
5616 if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
5617 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
5620 // If the source and destination are pointers, and this cast is equivalent
5621 // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
5622 // This can enhance SROA and other transforms that want type-safe pointers.
5623 Constant *ZeroUInt =
5624 Constant::getNullValue(Type::getInt32Ty(CI.getContext()));
5625 unsigned NumZeros = 0;
5626 while (SrcElTy != DstElTy &&
5627 isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
5628 SrcElTy->getNumContainedTypes() /* not "{}" */) {
5629 SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
5633 // If we found a path from the src to dest, create the getelementptr now.
5634 if (SrcElTy == DstElTy) {
5635 SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
5636 return GetElementPtrInst::CreateInBounds(Src, Idxs.begin(), Idxs.end(),"",
5637 ((Instruction*) NULL));
5641 if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
5642 if (DestVTy->getNumElements() == 1) {
5643 if (!isa<VectorType>(SrcTy)) {
5644 Value *Elem = Builder->CreateBitCast(Src, DestVTy->getElementType());
5645 return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
5646 Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
5648 // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
5652 if (const VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
5653 if (SrcVTy->getNumElements() == 1) {
5654 if (!isa<VectorType>(DestTy)) {
5656 Builder->CreateExtractElement(Src,
5657 Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
5658 return CastInst::Create(Instruction::BitCast, Elem, DestTy);
5663 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
5664 if (SVI->hasOneUse()) {
5665 // Okay, we have (bitconvert (shuffle ..)). Check to see if this is
5666 // a bitconvert to a vector with the same # elts.
5667 if (isa<VectorType>(DestTy) &&
5668 cast<VectorType>(DestTy)->getNumElements() ==
5669 SVI->getType()->getNumElements() &&
5670 SVI->getType()->getNumElements() ==
5671 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) {
5673 // If either of the operands is a cast from CI.getType(), then
5674 // evaluating the shuffle in the casted destination's type will allow
5675 // us to eliminate at least one cast.
5676 if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
5677 Tmp->getOperand(0)->getType() == DestTy) ||
5678 ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
5679 Tmp->getOperand(0)->getType() == DestTy)) {
5680 Value *LHS = Builder->CreateBitCast(SVI->getOperand(0), DestTy);
5681 Value *RHS = Builder->CreateBitCast(SVI->getOperand(1), DestTy);
5682 // Return a new shuffle vector. Use the same element ID's, as we
5683 // know the vector types match #elts.
5684 return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
5692 /// GetSelectFoldableOperands - We want to turn code that looks like this:
5694 /// %D = select %cond, %C, %A
5696 /// %C = select %cond, %B, 0
5699 /// Assuming that the specified instruction is an operand to the select, return
5700 /// a bitmask indicating which operands of this instruction are foldable if they
5701 /// equal the other incoming value of the select.
5703 static unsigned GetSelectFoldableOperands(Instruction *I) {
5704 switch (I->getOpcode()) {
5705 case Instruction::Add:
5706 case Instruction::Mul:
5707 case Instruction::And:
5708 case Instruction::Or:
5709 case Instruction::Xor:
5710 return 3; // Can fold through either operand.
5711 case Instruction::Sub: // Can only fold on the amount subtracted.
5712 case Instruction::Shl: // Can only fold on the shift amount.
5713 case Instruction::LShr:
5714 case Instruction::AShr:
5717 return 0; // Cannot fold
5721 /// GetSelectFoldableConstant - For the same transformation as the previous
5722 /// function, return the identity constant that goes into the select.
5723 static Constant *GetSelectFoldableConstant(Instruction *I) {
5724 switch (I->getOpcode()) {
5725 default: llvm_unreachable("This cannot happen!");
5726 case Instruction::Add:
5727 case Instruction::Sub:
5728 case Instruction::Or:
5729 case Instruction::Xor:
5730 case Instruction::Shl:
5731 case Instruction::LShr:
5732 case Instruction::AShr:
5733 return Constant::getNullValue(I->getType());
5734 case Instruction::And:
5735 return Constant::getAllOnesValue(I->getType());
5736 case Instruction::Mul:
5737 return ConstantInt::get(I->getType(), 1);
5741 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
5742 /// have the same opcode and only one use each. Try to simplify this.
5743 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
5745 if (TI->getNumOperands() == 1) {
5746 // If this is a non-volatile load or a cast from the same type,
5749 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
5752 return 0; // unknown unary op.
5755 // Fold this by inserting a select from the input values.
5756 SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0),
5757 FI->getOperand(0), SI.getName()+".v");
5758 InsertNewInstBefore(NewSI, SI);
5759 return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
5763 // Only handle binary operators here.
5764 if (!isa<BinaryOperator>(TI))
5767 // Figure out if the operations have any operands in common.
5768 Value *MatchOp, *OtherOpT, *OtherOpF;
5770 if (TI->getOperand(0) == FI->getOperand(0)) {
5771 MatchOp = TI->getOperand(0);
5772 OtherOpT = TI->getOperand(1);
5773 OtherOpF = FI->getOperand(1);
5774 MatchIsOpZero = true;
5775 } else if (TI->getOperand(1) == FI->getOperand(1)) {
5776 MatchOp = TI->getOperand(1);
5777 OtherOpT = TI->getOperand(0);
5778 OtherOpF = FI->getOperand(0);
5779 MatchIsOpZero = false;
5780 } else if (!TI->isCommutative()) {
5782 } else if (TI->getOperand(0) == FI->getOperand(1)) {
5783 MatchOp = TI->getOperand(0);
5784 OtherOpT = TI->getOperand(1);
5785 OtherOpF = FI->getOperand(0);
5786 MatchIsOpZero = true;
5787 } else if (TI->getOperand(1) == FI->getOperand(0)) {
5788 MatchOp = TI->getOperand(1);
5789 OtherOpT = TI->getOperand(0);
5790 OtherOpF = FI->getOperand(1);
5791 MatchIsOpZero = true;
5796 // If we reach here, they do have operations in common.
5797 SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
5798 OtherOpF, SI.getName()+".v");
5799 InsertNewInstBefore(NewSI, SI);
5801 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
5803 return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
5805 return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
5807 llvm_unreachable("Shouldn't get here");
5811 static bool isSelect01(Constant *C1, Constant *C2) {
5812 ConstantInt *C1I = dyn_cast<ConstantInt>(C1);
5815 ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
5818 return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne());
5821 /// FoldSelectIntoOp - Try fold the select into one of the operands to
5822 /// facilitate further optimization.
5823 Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
5825 // See the comment above GetSelectFoldableOperands for a description of the
5826 // transformation we are doing here.
5827 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
5828 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
5829 !isa<Constant>(FalseVal)) {
5830 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
5831 unsigned OpToFold = 0;
5832 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
5834 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
5839 Constant *C = GetSelectFoldableConstant(TVI);
5840 Value *OOp = TVI->getOperand(2-OpToFold);
5841 // Avoid creating select between 2 constants unless it's selecting
5843 if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
5844 Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
5845 InsertNewInstBefore(NewSel, SI);
5846 NewSel->takeName(TVI);
5847 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
5848 return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
5849 llvm_unreachable("Unknown instruction!!");
5856 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
5857 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
5858 !isa<Constant>(TrueVal)) {
5859 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
5860 unsigned OpToFold = 0;
5861 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
5863 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
5868 Constant *C = GetSelectFoldableConstant(FVI);
5869 Value *OOp = FVI->getOperand(2-OpToFold);
5870 // Avoid creating select between 2 constants unless it's selecting
5872 if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
5873 Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
5874 InsertNewInstBefore(NewSel, SI);
5875 NewSel->takeName(FVI);
5876 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
5877 return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
5878 llvm_unreachable("Unknown instruction!!");
5888 /// visitSelectInstWithICmp - Visit a SelectInst that has an
5889 /// ICmpInst as its first operand.
5891 Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
5893 bool Changed = false;
5894 ICmpInst::Predicate Pred = ICI->getPredicate();
5895 Value *CmpLHS = ICI->getOperand(0);
5896 Value *CmpRHS = ICI->getOperand(1);
5897 Value *TrueVal = SI.getTrueValue();
5898 Value *FalseVal = SI.getFalseValue();
5900 // Check cases where the comparison is with a constant that
5901 // can be adjusted to fit the min/max idiom. We may edit ICI in
5902 // place here, so make sure the select is the only user.
5903 if (ICI->hasOneUse())
5904 if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
5907 case ICmpInst::ICMP_ULT:
5908 case ICmpInst::ICMP_SLT: {
5909 // X < MIN ? T : F --> F
5910 if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
5911 return ReplaceInstUsesWith(SI, FalseVal);
5912 // X < C ? X : C-1 --> X > C-1 ? C-1 : X
5913 Constant *AdjustedRHS = SubOne(CI);
5914 if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
5915 (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
5916 Pred = ICmpInst::getSwappedPredicate(Pred);
5917 CmpRHS = AdjustedRHS;
5918 std::swap(FalseVal, TrueVal);
5919 ICI->setPredicate(Pred);
5920 ICI->setOperand(1, CmpRHS);
5921 SI.setOperand(1, TrueVal);
5922 SI.setOperand(2, FalseVal);
5927 case ICmpInst::ICMP_UGT:
5928 case ICmpInst::ICMP_SGT: {
5929 // X > MAX ? T : F --> F
5930 if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
5931 return ReplaceInstUsesWith(SI, FalseVal);
5932 // X > C ? X : C+1 --> X < C+1 ? C+1 : X
5933 Constant *AdjustedRHS = AddOne(CI);
5934 if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
5935 (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
5936 Pred = ICmpInst::getSwappedPredicate(Pred);
5937 CmpRHS = AdjustedRHS;
5938 std::swap(FalseVal, TrueVal);
5939 ICI->setPredicate(Pred);
5940 ICI->setOperand(1, CmpRHS);
5941 SI.setOperand(1, TrueVal);
5942 SI.setOperand(2, FalseVal);
5949 // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed
5950 // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed
5951 CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE;
5952 if (match(TrueVal, m_ConstantInt<-1>()) &&
5953 match(FalseVal, m_ConstantInt<0>()))
5954 Pred = ICI->getPredicate();
5955 else if (match(TrueVal, m_ConstantInt<0>()) &&
5956 match(FalseVal, m_ConstantInt<-1>()))
5957 Pred = CmpInst::getInversePredicate(ICI->getPredicate());
5959 if (Pred != CmpInst::BAD_ICMP_PREDICATE) {
5960 // If we are just checking for a icmp eq of a single bit and zext'ing it
5961 // to an integer, then shift the bit to the appropriate place and then
5962 // cast to integer to avoid the comparison.
5963 const APInt &Op1CV = CI->getValue();
5965 // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
5966 // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
5967 if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) ||
5968 (Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) {
5969 Value *In = ICI->getOperand(0);
5970 Value *Sh = ConstantInt::get(In->getType(),
5971 In->getType()->getScalarSizeInBits()-1);
5972 In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
5973 In->getName()+".lobit"),
5975 if (In->getType() != SI.getType())
5976 In = CastInst::CreateIntegerCast(In, SI.getType(),
5977 true/*SExt*/, "tmp", ICI);
5979 if (Pred == ICmpInst::ICMP_SGT)
5980 In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
5981 In->getName()+".not"), *ICI);
5983 return ReplaceInstUsesWith(SI, In);
5988 if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
5989 // Transform (X == Y) ? X : Y -> Y
5990 if (Pred == ICmpInst::ICMP_EQ)
5991 return ReplaceInstUsesWith(SI, FalseVal);
5992 // Transform (X != Y) ? X : Y -> X
5993 if (Pred == ICmpInst::ICMP_NE)
5994 return ReplaceInstUsesWith(SI, TrueVal);
5995 /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
5997 } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
5998 // Transform (X == Y) ? Y : X -> X
5999 if (Pred == ICmpInst::ICMP_EQ)
6000 return ReplaceInstUsesWith(SI, FalseVal);
6001 // Transform (X != Y) ? Y : X -> Y
6002 if (Pred == ICmpInst::ICMP_NE)
6003 return ReplaceInstUsesWith(SI, TrueVal);
6004 /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
6006 return Changed ? &SI : 0;
6010 /// CanSelectOperandBeMappingIntoPredBlock - SI is a select whose condition is a
6011 /// PHI node (but the two may be in different blocks). See if the true/false
6012 /// values (V) are live in all of the predecessor blocks of the PHI. For
6013 /// example, cases like this cannot be mapped:
6015 /// X = phi [ C1, BB1], [C2, BB2]
6017 /// Z = select X, Y, 0
6019 /// because Y is not live in BB1/BB2.
6021 static bool CanSelectOperandBeMappingIntoPredBlock(const Value *V,
6022 const SelectInst &SI) {
6023 // If the value is a non-instruction value like a constant or argument, it
6024 // can always be mapped.
6025 const Instruction *I = dyn_cast<Instruction>(V);
6026 if (I == 0) return true;
6028 // If V is a PHI node defined in the same block as the condition PHI, we can
6029 // map the arguments.
6030 const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
6032 if (const PHINode *VP = dyn_cast<PHINode>(I))
6033 if (VP->getParent() == CondPHI->getParent())
6036 // Otherwise, if the PHI and select are defined in the same block and if V is
6037 // defined in a different block, then we can transform it.
6038 if (SI.getParent() == CondPHI->getParent() &&
6039 I->getParent() != CondPHI->getParent())
6042 // Otherwise we have a 'hard' case and we can't tell without doing more
6043 // detailed dominator based analysis, punt.
6047 /// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form:
6048 /// SPF2(SPF1(A, B), C)
6049 Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
6050 SelectPatternFlavor SPF1,
6053 SelectPatternFlavor SPF2, Value *C) {
6054 if (C == A || C == B) {
6055 // MAX(MAX(A, B), B) -> MAX(A, B)
6056 // MIN(MIN(a, b), a) -> MIN(a, b)
6058 return ReplaceInstUsesWith(Outer, Inner);
6060 // MAX(MIN(a, b), a) -> a
6061 // MIN(MAX(a, b), a) -> a
6062 if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
6063 (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
6064 (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
6065 (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
6066 return ReplaceInstUsesWith(Outer, C);
6069 // TODO: MIN(MIN(A, 23), 97)
6076 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
6077 Value *CondVal = SI.getCondition();
6078 Value *TrueVal = SI.getTrueValue();
6079 Value *FalseVal = SI.getFalseValue();
6081 // select true, X, Y -> X
6082 // select false, X, Y -> Y
6083 if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
6084 return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
6086 // select C, X, X -> X
6087 if (TrueVal == FalseVal)
6088 return ReplaceInstUsesWith(SI, TrueVal);
6090 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
6091 return ReplaceInstUsesWith(SI, FalseVal);
6092 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
6093 return ReplaceInstUsesWith(SI, TrueVal);
6094 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
6095 if (isa<Constant>(TrueVal))
6096 return ReplaceInstUsesWith(SI, TrueVal);
6098 return ReplaceInstUsesWith(SI, FalseVal);
6101 if (SI.getType() == Type::getInt1Ty(SI.getContext())) {
6102 if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
6103 if (C->getZExtValue()) {
6104 // Change: A = select B, true, C --> A = or B, C
6105 return BinaryOperator::CreateOr(CondVal, FalseVal);
6107 // Change: A = select B, false, C --> A = and !B, C
6109 InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
6110 "not."+CondVal->getName()), SI);
6111 return BinaryOperator::CreateAnd(NotCond, FalseVal);
6113 } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
6114 if (C->getZExtValue() == false) {
6115 // Change: A = select B, C, false --> A = and B, C
6116 return BinaryOperator::CreateAnd(CondVal, TrueVal);
6118 // Change: A = select B, C, true --> A = or !B, C
6120 InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
6121 "not."+CondVal->getName()), SI);
6122 return BinaryOperator::CreateOr(NotCond, TrueVal);
6126 // select a, b, a -> a&b
6127 // select a, a, b -> a|b
6128 if (CondVal == TrueVal)
6129 return BinaryOperator::CreateOr(CondVal, FalseVal);
6130 else if (CondVal == FalseVal)
6131 return BinaryOperator::CreateAnd(CondVal, TrueVal);
6134 // Selecting between two integer constants?
6135 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
6136 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
6137 // select C, 1, 0 -> zext C to int
6138 if (FalseValC->isZero() && TrueValC->getValue() == 1) {
6139 return CastInst::Create(Instruction::ZExt, CondVal, SI.getType());
6140 } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
6141 // select C, 0, 1 -> zext !C to int
6143 InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
6144 "not."+CondVal->getName()), SI);
6145 return CastInst::Create(Instruction::ZExt, NotCond, SI.getType());
6148 if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
6149 // If one of the constants is zero (we know they can't both be) and we
6150 // have an icmp instruction with zero, and we have an 'and' with the
6151 // non-constant value, eliminate this whole mess. This corresponds to
6152 // cases like this: ((X & 27) ? 27 : 0)
6153 if (TrueValC->isZero() || FalseValC->isZero())
6154 if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
6155 cast<Constant>(IC->getOperand(1))->isNullValue())
6156 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
6157 if (ICA->getOpcode() == Instruction::And &&
6158 isa<ConstantInt>(ICA->getOperand(1)) &&
6159 (ICA->getOperand(1) == TrueValC ||
6160 ICA->getOperand(1) == FalseValC) &&
6161 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
6162 // Okay, now we know that everything is set up, we just don't
6163 // know whether we have a icmp_ne or icmp_eq and whether the
6164 // true or false val is the zero.
6165 bool ShouldNotVal = !TrueValC->isZero();
6166 ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
6169 V = InsertNewInstBefore(BinaryOperator::Create(
6170 Instruction::Xor, V, ICA->getOperand(1)), SI);
6171 return ReplaceInstUsesWith(SI, V);
6176 // See if we are selecting two values based on a comparison of the two values.
6177 if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
6178 if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
6179 // Transform (X == Y) ? X : Y -> Y
6180 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
6181 // This is not safe in general for floating point:
6182 // consider X== -0, Y== +0.
6183 // It becomes safe if either operand is a nonzero constant.
6184 ConstantFP *CFPt, *CFPf;
6185 if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
6186 !CFPt->getValueAPF().isZero()) ||
6187 ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
6188 !CFPf->getValueAPF().isZero()))
6189 return ReplaceInstUsesWith(SI, FalseVal);
6191 // Transform (X != Y) ? X : Y -> X
6192 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
6193 return ReplaceInstUsesWith(SI, TrueVal);
6194 // NOTE: if we wanted to, this is where to detect MIN/MAX
6196 } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
6197 // Transform (X == Y) ? Y : X -> X
6198 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
6199 // This is not safe in general for floating point:
6200 // consider X== -0, Y== +0.
6201 // It becomes safe if either operand is a nonzero constant.
6202 ConstantFP *CFPt, *CFPf;
6203 if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
6204 !CFPt->getValueAPF().isZero()) ||
6205 ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
6206 !CFPf->getValueAPF().isZero()))
6207 return ReplaceInstUsesWith(SI, FalseVal);
6209 // Transform (X != Y) ? Y : X -> Y
6210 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
6211 return ReplaceInstUsesWith(SI, TrueVal);
6212 // NOTE: if we wanted to, this is where to detect MIN/MAX
6214 // NOTE: if we wanted to, this is where to detect ABS
6217 // See if we are selecting two values based on a comparison of the two values.
6218 if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
6219 if (Instruction *Result = visitSelectInstWithICmp(SI, ICI))
6222 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
6223 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
6224 if (TI->hasOneUse() && FI->hasOneUse()) {
6225 Instruction *AddOp = 0, *SubOp = 0;
6227 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
6228 if (TI->getOpcode() == FI->getOpcode())
6229 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
6232 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
6233 // even legal for FP.
6234 if ((TI->getOpcode() == Instruction::Sub &&
6235 FI->getOpcode() == Instruction::Add) ||
6236 (TI->getOpcode() == Instruction::FSub &&
6237 FI->getOpcode() == Instruction::FAdd)) {
6238 AddOp = FI; SubOp = TI;
6239 } else if ((FI->getOpcode() == Instruction::Sub &&
6240 TI->getOpcode() == Instruction::Add) ||
6241 (FI->getOpcode() == Instruction::FSub &&
6242 TI->getOpcode() == Instruction::FAdd)) {
6243 AddOp = TI; SubOp = FI;
6247 Value *OtherAddOp = 0;
6248 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
6249 OtherAddOp = AddOp->getOperand(1);
6250 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
6251 OtherAddOp = AddOp->getOperand(0);
6255 // So at this point we know we have (Y -> OtherAddOp):
6256 // select C, (add X, Y), (sub X, Z)
6257 Value *NegVal; // Compute -Z
6258 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
6259 NegVal = ConstantExpr::getNeg(C);
6261 NegVal = InsertNewInstBefore(
6262 BinaryOperator::CreateNeg(SubOp->getOperand(1),
6266 Value *NewTrueOp = OtherAddOp;
6267 Value *NewFalseOp = NegVal;
6269 std::swap(NewTrueOp, NewFalseOp);
6270 Instruction *NewSel =
6271 SelectInst::Create(CondVal, NewTrueOp,
6272 NewFalseOp, SI.getName() + ".p");
6274 NewSel = InsertNewInstBefore(NewSel, SI);
6275 return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
6280 // See if we can fold the select into one of our operands.
6281 if (SI.getType()->isInteger()) {
6282 if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
6285 // MAX(MAX(a, b), a) -> MAX(a, b)
6286 // MIN(MIN(a, b), a) -> MIN(a, b)
6287 // MAX(MIN(a, b), a) -> a
6288 // MIN(MAX(a, b), a) -> a
6289 Value *LHS, *RHS, *LHS2, *RHS2;
6290 if (SelectPatternFlavor SPF = MatchSelectPattern(&SI, LHS, RHS)) {
6291 if (SelectPatternFlavor SPF2 = MatchSelectPattern(LHS, LHS2, RHS2))
6292 if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
6295 if (SelectPatternFlavor SPF2 = MatchSelectPattern(RHS, LHS2, RHS2))
6296 if (Instruction *R = FoldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2,
6302 // ABS(-X) -> ABS(X)
6303 // ABS(ABS(X)) -> ABS(X)
6306 // See if we can fold the select into a phi node if the condition is a select.
6307 if (isa<PHINode>(SI.getCondition()))
6308 // The true/false values have to be live in the PHI predecessor's blocks.
6309 if (CanSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
6310 CanSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
6311 if (Instruction *NV = FoldOpIntoPhi(SI))
6314 if (BinaryOperator::isNot(CondVal)) {
6315 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
6316 SI.setOperand(1, FalseVal);
6317 SI.setOperand(2, TrueVal);
6324 /// EnforceKnownAlignment - If the specified pointer points to an object that
6325 /// we control, modify the object's alignment to PrefAlign. This isn't
6326 /// often possible though. If alignment is important, a more reliable approach
6327 /// is to simply align all global variables and allocation instructions to
6328 /// their preferred alignment from the beginning.
6330 static unsigned EnforceKnownAlignment(Value *V,
6331 unsigned Align, unsigned PrefAlign) {
6333 User *U = dyn_cast<User>(V);
6334 if (!U) return Align;
6336 switch (Operator::getOpcode(U)) {
6338 case Instruction::BitCast:
6339 return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
6340 case Instruction::GetElementPtr: {
6341 // If all indexes are zero, it is just the alignment of the base pointer.
6342 bool AllZeroOperands = true;
6343 for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i)
6344 if (!isa<Constant>(*i) ||
6345 !cast<Constant>(*i)->isNullValue()) {
6346 AllZeroOperands = false;
6350 if (AllZeroOperands) {
6351 // Treat this like a bitcast.
6352 return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
6358 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
6359 // If there is a large requested alignment and we can, bump up the alignment
6361 if (!GV->isDeclaration()) {
6362 if (GV->getAlignment() >= PrefAlign)
6363 Align = GV->getAlignment();
6365 GV->setAlignment(PrefAlign);
6369 } else if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
6370 // If there is a requested alignment and if this is an alloca, round up.
6371 if (AI->getAlignment() >= PrefAlign)
6372 Align = AI->getAlignment();
6374 AI->setAlignment(PrefAlign);
6382 /// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
6383 /// we can determine, return it, otherwise return 0. If PrefAlign is specified,
6384 /// and it is more than the alignment of the ultimate object, see if we can
6385 /// increase the alignment of the ultimate object, making this check succeed.
6386 unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V,
6387 unsigned PrefAlign) {
6388 unsigned BitWidth = TD ? TD->getTypeSizeInBits(V->getType()) :
6389 sizeof(PrefAlign) * CHAR_BIT;
6390 APInt Mask = APInt::getAllOnesValue(BitWidth);
6391 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
6392 ComputeMaskedBits(V, Mask, KnownZero, KnownOne);
6393 unsigned TrailZ = KnownZero.countTrailingOnes();
6394 unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
6396 if (PrefAlign > Align)
6397 Align = EnforceKnownAlignment(V, Align, PrefAlign);
6399 // We don't need to make any adjustment.
6403 Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
6404 unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getOperand(1));
6405 unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2));
6406 unsigned MinAlign = std::min(DstAlign, SrcAlign);
6407 unsigned CopyAlign = MI->getAlignment();
6409 if (CopyAlign < MinAlign) {
6410 MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
6415 // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
6417 ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getOperand(3));
6418 if (MemOpLength == 0) return 0;
6420 // Source and destination pointer types are always "i8*" for intrinsic. See
6421 // if the size is something we can handle with a single primitive load/store.
6422 // A single load+store correctly handles overlapping memory in the memmove
6424 unsigned Size = MemOpLength->getZExtValue();
6425 if (Size == 0) return MI; // Delete this mem transfer.
6427 if (Size > 8 || (Size&(Size-1)))
6428 return 0; // If not 1/2/4/8 bytes, exit.
6430 // Use an integer load+store unless we can find something better.
6432 PointerType::getUnqual(IntegerType::get(MI->getContext(), Size<<3));
6434 // Memcpy forces the use of i8* for the source and destination. That means
6435 // that if you're using memcpy to move one double around, you'll get a cast
6436 // from double* to i8*. We'd much rather use a double load+store rather than
6437 // an i64 load+store, here because this improves the odds that the source or
6438 // dest address will be promotable. See if we can find a better type than the
6439 // integer datatype.
6440 if (Value *Op = getBitCastOperand(MI->getOperand(1))) {
6441 const Type *SrcETy = cast<PointerType>(Op->getType())->getElementType();
6442 if (TD && SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
6443 // The SrcETy might be something like {{{double}}} or [1 x double]. Rip
6444 // down through these levels if so.
6445 while (!SrcETy->isSingleValueType()) {
6446 if (const StructType *STy = dyn_cast<StructType>(SrcETy)) {
6447 if (STy->getNumElements() == 1)
6448 SrcETy = STy->getElementType(0);
6451 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcETy)) {
6452 if (ATy->getNumElements() == 1)
6453 SrcETy = ATy->getElementType();
6460 if (SrcETy->isSingleValueType())
6461 NewPtrTy = PointerType::getUnqual(SrcETy);
6466 // If the memcpy/memmove provides better alignment info than we can
6468 SrcAlign = std::max(SrcAlign, CopyAlign);
6469 DstAlign = std::max(DstAlign, CopyAlign);
6471 Value *Src = Builder->CreateBitCast(MI->getOperand(2), NewPtrTy);
6472 Value *Dest = Builder->CreateBitCast(MI->getOperand(1), NewPtrTy);
6473 Instruction *L = new LoadInst(Src, "tmp", false, SrcAlign);
6474 InsertNewInstBefore(L, *MI);
6475 InsertNewInstBefore(new StoreInst(L, Dest, false, DstAlign), *MI);
6477 // Set the size of the copy to 0, it will be deleted on the next iteration.
6478 MI->setOperand(3, Constant::getNullValue(MemOpLength->getType()));
6482 Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
6483 unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest());
6484 if (MI->getAlignment() < Alignment) {
6485 MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
6490 // Extract the length and alignment and fill if they are constant.
6491 ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
6492 ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
6493 if (!LenC || !FillC || FillC->getType() != Type::getInt8Ty(MI->getContext()))
6495 uint64_t Len = LenC->getZExtValue();
6496 Alignment = MI->getAlignment();
6498 // If the length is zero, this is a no-op
6499 if (Len == 0) return MI; // memset(d,c,0,a) -> noop
6501 // memset(s,c,n) -> store s, c (for n=1,2,4,8)
6502 if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
6503 const Type *ITy = IntegerType::get(MI->getContext(), Len*8); // n=1 -> i8.
6505 Value *Dest = MI->getDest();
6506 Dest = Builder->CreateBitCast(Dest, PointerType::getUnqual(ITy));
6508 // Alignment 0 is identity for alignment 1 for memset, but not store.
6509 if (Alignment == 0) Alignment = 1;
6511 // Extract the fill value and store.
6512 uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
6513 InsertNewInstBefore(new StoreInst(ConstantInt::get(ITy, Fill),
6514 Dest, false, Alignment), *MI);
6516 // Set the size of the copy to 0, it will be deleted on the next iteration.
6517 MI->setLength(Constant::getNullValue(LenC->getType()));
6525 /// visitCallInst - CallInst simplification. This mostly only handles folding
6526 /// of intrinsic instructions. For normal calls, it allows visitCallSite to do
6527 /// the heavy lifting.
6529 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
6530 if (isFreeCall(&CI))
6531 return visitFree(CI);
6533 // If the caller function is nounwind, mark the call as nounwind, even if the
6535 if (CI.getParent()->getParent()->doesNotThrow() &&
6536 !CI.doesNotThrow()) {
6537 CI.setDoesNotThrow();
6541 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
6542 if (!II) return visitCallSite(&CI);
6544 // Intrinsics cannot occur in an invoke, so handle them here instead of in
6546 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
6547 bool Changed = false;
6549 // memmove/cpy/set of zero bytes is a noop.
6550 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
6551 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
6553 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
6554 if (CI->getZExtValue() == 1) {
6555 // Replace the instruction with just byte operations. We would
6556 // transform other cases to loads/stores, but we don't know if
6557 // alignment is sufficient.
6561 // If we have a memmove and the source operation is a constant global,
6562 // then the source and dest pointers can't alias, so we can change this
6563 // into a call to memcpy.
6564 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
6565 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
6566 if (GVSrc->isConstant()) {
6567 Module *M = CI.getParent()->getParent()->getParent();
6568 Intrinsic::ID MemCpyID = Intrinsic::memcpy;
6570 Tys[0] = CI.getOperand(3)->getType();
6572 Intrinsic::getDeclaration(M, MemCpyID, Tys, 1));
6577 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
6578 // memmove(x,x,size) -> noop.
6579 if (MTI->getSource() == MTI->getDest())
6580 return EraseInstFromFunction(CI);
6583 // If we can determine a pointer alignment that is bigger than currently
6584 // set, update the alignment.
6585 if (isa<MemTransferInst>(MI)) {
6586 if (Instruction *I = SimplifyMemTransfer(MI))
6588 } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
6589 if (Instruction *I = SimplifyMemSet(MSI))
6593 if (Changed) return II;
6596 switch (II->getIntrinsicID()) {
6598 case Intrinsic::bswap:
6599 // bswap(bswap(x)) -> x
6600 if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getOperand(1)))
6601 if (Operand->getIntrinsicID() == Intrinsic::bswap)
6602 return ReplaceInstUsesWith(CI, Operand->getOperand(1));
6604 // bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
6605 if (TruncInst *TI = dyn_cast<TruncInst>(II->getOperand(1))) {
6606 if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(TI->getOperand(0)))
6607 if (Operand->getIntrinsicID() == Intrinsic::bswap) {
6608 unsigned C = Operand->getType()->getPrimitiveSizeInBits() -
6609 TI->getType()->getPrimitiveSizeInBits();
6610 Value *CV = ConstantInt::get(Operand->getType(), C);
6611 Value *V = Builder->CreateLShr(Operand->getOperand(1), CV);
6612 return new TruncInst(V, TI->getType());
6617 case Intrinsic::powi:
6618 if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getOperand(2))) {
6619 // powi(x, 0) -> 1.0
6620 if (Power->isZero())
6621 return ReplaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0));
6624 return ReplaceInstUsesWith(CI, II->getOperand(1));
6625 // powi(x, -1) -> 1/x
6626 if (Power->isAllOnesValue())
6627 return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0),
6632 case Intrinsic::uadd_with_overflow: {
6633 Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
6634 const IntegerType *IT = cast<IntegerType>(II->getOperand(1)->getType());
6635 uint32_t BitWidth = IT->getBitWidth();
6636 APInt Mask = APInt::getSignBit(BitWidth);
6637 APInt LHSKnownZero(BitWidth, 0);
6638 APInt LHSKnownOne(BitWidth, 0);
6639 ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
6640 bool LHSKnownNegative = LHSKnownOne[BitWidth - 1];
6641 bool LHSKnownPositive = LHSKnownZero[BitWidth - 1];
6643 if (LHSKnownNegative || LHSKnownPositive) {
6644 APInt RHSKnownZero(BitWidth, 0);
6645 APInt RHSKnownOne(BitWidth, 0);
6646 ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
6647 bool RHSKnownNegative = RHSKnownOne[BitWidth - 1];
6648 bool RHSKnownPositive = RHSKnownZero[BitWidth - 1];
6649 if (LHSKnownNegative && RHSKnownNegative) {
6650 // The sign bit is set in both cases: this MUST overflow.
6651 // Create a simple add instruction, and insert it into the struct.
6652 Instruction *Add = BinaryOperator::CreateAdd(LHS, RHS, "", &CI);
6655 UndefValue::get(LHS->getType()),ConstantInt::getTrue(II->getContext())
6657 Constant *Struct = ConstantStruct::get(II->getContext(), V, 2, false);
6658 return InsertValueInst::Create(Struct, Add, 0);
6661 if (LHSKnownPositive && RHSKnownPositive) {
6662 // The sign bit is clear in both cases: this CANNOT overflow.
6663 // Create a simple add instruction, and insert it into the struct.
6664 Instruction *Add = BinaryOperator::CreateNUWAdd(LHS, RHS, "", &CI);
6667 UndefValue::get(LHS->getType()),
6668 ConstantInt::getFalse(II->getContext())
6670 Constant *Struct = ConstantStruct::get(II->getContext(), V, 2, false);
6671 return InsertValueInst::Create(Struct, Add, 0);
6675 // FALL THROUGH uadd into sadd
6676 case Intrinsic::sadd_with_overflow:
6677 // Canonicalize constants into the RHS.
6678 if (isa<Constant>(II->getOperand(1)) &&
6679 !isa<Constant>(II->getOperand(2))) {
6680 Value *LHS = II->getOperand(1);
6681 II->setOperand(1, II->getOperand(2));
6682 II->setOperand(2, LHS);
6686 // X + undef -> undef
6687 if (isa<UndefValue>(II->getOperand(2)))
6688 return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
6690 if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getOperand(2))) {
6691 // X + 0 -> {X, false}
6692 if (RHS->isZero()) {
6694 UndefValue::get(II->getOperand(0)->getType()),
6695 ConstantInt::getFalse(II->getContext())
6697 Constant *Struct = ConstantStruct::get(II->getContext(), V, 2, false);
6698 return InsertValueInst::Create(Struct, II->getOperand(1), 0);
6702 case Intrinsic::usub_with_overflow:
6703 case Intrinsic::ssub_with_overflow:
6704 // undef - X -> undef
6705 // X - undef -> undef
6706 if (isa<UndefValue>(II->getOperand(1)) ||
6707 isa<UndefValue>(II->getOperand(2)))
6708 return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
6710 if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getOperand(2))) {
6711 // X - 0 -> {X, false}
6712 if (RHS->isZero()) {
6714 UndefValue::get(II->getOperand(1)->getType()),
6715 ConstantInt::getFalse(II->getContext())
6717 Constant *Struct = ConstantStruct::get(II->getContext(), V, 2, false);
6718 return InsertValueInst::Create(Struct, II->getOperand(1), 0);
6722 case Intrinsic::umul_with_overflow:
6723 case Intrinsic::smul_with_overflow:
6724 // Canonicalize constants into the RHS.
6725 if (isa<Constant>(II->getOperand(1)) &&
6726 !isa<Constant>(II->getOperand(2))) {
6727 Value *LHS = II->getOperand(1);
6728 II->setOperand(1, II->getOperand(2));
6729 II->setOperand(2, LHS);
6733 // X * undef -> undef
6734 if (isa<UndefValue>(II->getOperand(2)))
6735 return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
6737 if (ConstantInt *RHSI = dyn_cast<ConstantInt>(II->getOperand(2))) {
6738 // X*0 -> {0, false}
6740 return ReplaceInstUsesWith(CI, Constant::getNullValue(II->getType()));
6742 // X * 1 -> {X, false}
6743 if (RHSI->equalsInt(1)) {
6745 UndefValue::get(II->getOperand(1)->getType()),
6746 ConstantInt::getFalse(II->getContext())
6748 Constant *Struct = ConstantStruct::get(II->getContext(), V, 2, false);
6749 return InsertValueInst::Create(Struct, II->getOperand(1), 0);
6753 case Intrinsic::ppc_altivec_lvx:
6754 case Intrinsic::ppc_altivec_lvxl:
6755 case Intrinsic::x86_sse_loadu_ps:
6756 case Intrinsic::x86_sse2_loadu_pd:
6757 case Intrinsic::x86_sse2_loadu_dq:
6758 // Turn PPC lvx -> load if the pointer is known aligned.
6759 // Turn X86 loadups -> load if the pointer is known aligned.
6760 if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
6761 Value *Ptr = Builder->CreateBitCast(II->getOperand(1),
6762 PointerType::getUnqual(II->getType()));
6763 return new LoadInst(Ptr);
6766 case Intrinsic::ppc_altivec_stvx:
6767 case Intrinsic::ppc_altivec_stvxl:
6768 // Turn stvx -> store if the pointer is known aligned.
6769 if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) {
6770 const Type *OpPtrTy =
6771 PointerType::getUnqual(II->getOperand(1)->getType());
6772 Value *Ptr = Builder->CreateBitCast(II->getOperand(2), OpPtrTy);
6773 return new StoreInst(II->getOperand(1), Ptr);
6776 case Intrinsic::x86_sse_storeu_ps:
6777 case Intrinsic::x86_sse2_storeu_pd:
6778 case Intrinsic::x86_sse2_storeu_dq:
6779 // Turn X86 storeu -> store if the pointer is known aligned.
6780 if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
6781 const Type *OpPtrTy =
6782 PointerType::getUnqual(II->getOperand(2)->getType());
6783 Value *Ptr = Builder->CreateBitCast(II->getOperand(1), OpPtrTy);
6784 return new StoreInst(II->getOperand(2), Ptr);
6788 case Intrinsic::x86_sse_cvttss2si: {
6789 // These intrinsics only demands the 0th element of its input vector. If
6790 // we can simplify the input based on that, do so now.
6792 cast<VectorType>(II->getOperand(1)->getType())->getNumElements();
6793 APInt DemandedElts(VWidth, 1);
6794 APInt UndefElts(VWidth, 0);
6795 if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
6797 II->setOperand(1, V);
6803 case Intrinsic::ppc_altivec_vperm:
6804 // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
6805 if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
6806 assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
6808 // Check that all of the elements are integer constants or undefs.
6809 bool AllEltsOk = true;
6810 for (unsigned i = 0; i != 16; ++i) {
6811 if (!isa<ConstantInt>(Mask->getOperand(i)) &&
6812 !isa<UndefValue>(Mask->getOperand(i))) {
6819 // Cast the input vectors to byte vectors.
6820 Value *Op0 = Builder->CreateBitCast(II->getOperand(1), Mask->getType());
6821 Value *Op1 = Builder->CreateBitCast(II->getOperand(2), Mask->getType());
6822 Value *Result = UndefValue::get(Op0->getType());
6824 // Only extract each element once.
6825 Value *ExtractedElts[32];
6826 memset(ExtractedElts, 0, sizeof(ExtractedElts));
6828 for (unsigned i = 0; i != 16; ++i) {
6829 if (isa<UndefValue>(Mask->getOperand(i)))
6831 unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
6832 Idx &= 31; // Match the hardware behavior.
6834 if (ExtractedElts[Idx] == 0) {
6835 ExtractedElts[Idx] =
6836 Builder->CreateExtractElement(Idx < 16 ? Op0 : Op1,
6837 ConstantInt::get(Type::getInt32Ty(II->getContext()),
6838 Idx&15, false), "tmp");
6841 // Insert this value into the result vector.
6842 Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx],
6843 ConstantInt::get(Type::getInt32Ty(II->getContext()),
6846 return CastInst::Create(Instruction::BitCast, Result, CI.getType());
6851 case Intrinsic::stackrestore: {
6852 // If the save is right next to the restore, remove the restore. This can
6853 // happen when variable allocas are DCE'd.
6854 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
6855 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
6856 BasicBlock::iterator BI = SS;
6858 return EraseInstFromFunction(CI);
6862 // Scan down this block to see if there is another stack restore in the
6863 // same block without an intervening call/alloca.
6864 BasicBlock::iterator BI = II;
6865 TerminatorInst *TI = II->getParent()->getTerminator();
6866 bool CannotRemove = false;
6867 for (++BI; &*BI != TI; ++BI) {
6868 if (isa<AllocaInst>(BI) || isMalloc(BI)) {
6869 CannotRemove = true;
6872 if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
6873 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
6874 // If there is a stackrestore below this one, remove this one.
6875 if (II->getIntrinsicID() == Intrinsic::stackrestore)
6876 return EraseInstFromFunction(CI);
6877 // Otherwise, ignore the intrinsic.
6879 // If we found a non-intrinsic call, we can't remove the stack
6881 CannotRemove = true;
6887 // If the stack restore is in a return/unwind block and if there are no
6888 // allocas or calls between the restore and the return, nuke the restore.
6889 if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)))
6890 return EraseInstFromFunction(CI);
6895 return visitCallSite(II);
6898 // InvokeInst simplification
6900 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
6901 return visitCallSite(&II);
6904 /// isSafeToEliminateVarargsCast - If this cast does not affect the value
6905 /// passed through the varargs area, we can eliminate the use of the cast.
6906 static bool isSafeToEliminateVarargsCast(const CallSite CS,
6907 const CastInst * const CI,
6908 const TargetData * const TD,
6910 if (!CI->isLosslessCast())
6913 // The size of ByVal arguments is derived from the type, so we
6914 // can't change to a type with a different size. If the size were
6915 // passed explicitly we could avoid this check.
6916 if (!CS.paramHasAttr(ix, Attribute::ByVal))
6920 cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
6921 const Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
6922 if (!SrcTy->isSized() || !DstTy->isSized())
6924 if (!TD || TD->getTypeAllocSize(SrcTy) != TD->getTypeAllocSize(DstTy))
6929 // visitCallSite - Improvements for call and invoke instructions.
6931 Instruction *InstCombiner::visitCallSite(CallSite CS) {
6932 bool Changed = false;
6934 // If the callee is a constexpr cast of a function, attempt to move the cast
6935 // to the arguments of the call/invoke.
6936 if (transformConstExprCastCall(CS)) return 0;
6938 Value *Callee = CS.getCalledValue();
6940 if (Function *CalleeF = dyn_cast<Function>(Callee))
6941 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
6942 Instruction *OldCall = CS.getInstruction();
6943 // If the call and callee calling conventions don't match, this call must
6944 // be unreachable, as the call is undefined.
6945 new StoreInst(ConstantInt::getTrue(Callee->getContext()),
6946 UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
6948 // If OldCall dues not return void then replaceAllUsesWith undef.
6949 // This allows ValueHandlers and custom metadata to adjust itself.
6950 if (!OldCall->getType()->isVoidTy())
6951 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
6952 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
6953 return EraseInstFromFunction(*OldCall);
6957 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
6958 // This instruction is not reachable, just remove it. We insert a store to
6959 // undef so that we know that this code is not reachable, despite the fact
6960 // that we can't modify the CFG here.
6961 new StoreInst(ConstantInt::getTrue(Callee->getContext()),
6962 UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
6963 CS.getInstruction());
6965 // If CS dues not return void then replaceAllUsesWith undef.
6966 // This allows ValueHandlers and custom metadata to adjust itself.
6967 if (!CS.getInstruction()->getType()->isVoidTy())
6968 CS.getInstruction()->
6969 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
6971 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
6972 // Don't break the CFG, insert a dummy cond branch.
6973 BranchInst::Create(II->getNormalDest(), II->getUnwindDest(),
6974 ConstantInt::getTrue(Callee->getContext()), II);
6976 return EraseInstFromFunction(*CS.getInstruction());
6979 if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee))
6980 if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0)))
6981 if (In->getIntrinsicID() == Intrinsic::init_trampoline)
6982 return transformCallThroughTrampoline(CS);
6984 const PointerType *PTy = cast<PointerType>(Callee->getType());
6985 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
6986 if (FTy->isVarArg()) {
6987 int ix = FTy->getNumParams() + (isa<InvokeInst>(Callee) ? 3 : 1);
6988 // See if we can optimize any arguments passed through the varargs area of
6990 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
6991 E = CS.arg_end(); I != E; ++I, ++ix) {
6992 CastInst *CI = dyn_cast<CastInst>(*I);
6993 if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
6994 *I = CI->getOperand(0);
7000 if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
7001 // Inline asm calls cannot throw - mark them 'nounwind'.
7002 CS.setDoesNotThrow();
7006 return Changed ? CS.getInstruction() : 0;
7009 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
7010 // attempt to move the cast to the arguments of the call/invoke.
7012 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
7013 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
7014 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
7015 if (CE->getOpcode() != Instruction::BitCast ||
7016 !isa<Function>(CE->getOperand(0)))
7018 Function *Callee = cast<Function>(CE->getOperand(0));
7019 Instruction *Caller = CS.getInstruction();
7020 const AttrListPtr &CallerPAL = CS.getAttributes();
7022 // Okay, this is a cast from a function to a different type. Unless doing so
7023 // would cause a type conversion of one of our arguments, change this call to
7024 // be a direct call with arguments casted to the appropriate types.
7026 const FunctionType *FT = Callee->getFunctionType();
7027 const Type *OldRetTy = Caller->getType();
7028 const Type *NewRetTy = FT->getReturnType();
7030 if (isa<StructType>(NewRetTy))
7031 return false; // TODO: Handle multiple return values.
7033 // Check to see if we are changing the return type...
7034 if (OldRetTy != NewRetTy) {
7035 if (Callee->isDeclaration() &&
7036 // Conversion is ok if changing from one pointer type to another or from
7037 // a pointer to an integer of the same size.
7038 !((isa<PointerType>(OldRetTy) || !TD ||
7039 OldRetTy == TD->getIntPtrType(Caller->getContext())) &&
7040 (isa<PointerType>(NewRetTy) || !TD ||
7041 NewRetTy == TD->getIntPtrType(Caller->getContext()))))
7042 return false; // Cannot transform this return value.
7044 if (!Caller->use_empty() &&
7045 // void -> non-void is handled specially
7046 !NewRetTy->isVoidTy() && !CastInst::isCastable(NewRetTy, OldRetTy))
7047 return false; // Cannot transform this return value.
7049 if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
7050 Attributes RAttrs = CallerPAL.getRetAttributes();
7051 if (RAttrs & Attribute::typeIncompatible(NewRetTy))
7052 return false; // Attribute not compatible with transformed value.
7055 // If the callsite is an invoke instruction, and the return value is used by
7056 // a PHI node in a successor, we cannot change the return type of the call
7057 // because there is no place to put the cast instruction (without breaking
7058 // the critical edge). Bail out in this case.
7059 if (!Caller->use_empty())
7060 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
7061 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
7063 if (PHINode *PN = dyn_cast<PHINode>(*UI))
7064 if (PN->getParent() == II->getNormalDest() ||
7065 PN->getParent() == II->getUnwindDest())
7069 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
7070 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
7072 CallSite::arg_iterator AI = CS.arg_begin();
7073 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
7074 const Type *ParamTy = FT->getParamType(i);
7075 const Type *ActTy = (*AI)->getType();
7077 if (!CastInst::isCastable(ActTy, ParamTy))
7078 return false; // Cannot transform this parameter value.
7080 if (CallerPAL.getParamAttributes(i + 1)
7081 & Attribute::typeIncompatible(ParamTy))
7082 return false; // Attribute not compatible with transformed value.
7084 // Converting from one pointer type to another or between a pointer and an
7085 // integer of the same size is safe even if we do not have a body.
7086 bool isConvertible = ActTy == ParamTy ||
7087 (TD && ((isa<PointerType>(ParamTy) ||
7088 ParamTy == TD->getIntPtrType(Caller->getContext())) &&
7089 (isa<PointerType>(ActTy) ||
7090 ActTy == TD->getIntPtrType(Caller->getContext()))));
7091 if (Callee->isDeclaration() && !isConvertible) return false;
7094 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
7095 Callee->isDeclaration())
7096 return false; // Do not delete arguments unless we have a function body.
7098 if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
7099 !CallerPAL.isEmpty())
7100 // In this case we have more arguments than the new function type, but we
7101 // won't be dropping them. Check that these extra arguments have attributes
7102 // that are compatible with being a vararg call argument.
7103 for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
7104 if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
7106 Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
7107 if (PAttrs & Attribute::VarArgsIncompatible)
7111 // Okay, we decided that this is a safe thing to do: go ahead and start
7112 // inserting cast instructions as necessary...
7113 std::vector<Value*> Args;
7114 Args.reserve(NumActualArgs);
7115 SmallVector<AttributeWithIndex, 8> attrVec;
7116 attrVec.reserve(NumCommonArgs);
7118 // Get any return attributes.
7119 Attributes RAttrs = CallerPAL.getRetAttributes();
7121 // If the return value is not being used, the type may not be compatible
7122 // with the existing attributes. Wipe out any problematic attributes.
7123 RAttrs &= ~Attribute::typeIncompatible(NewRetTy);
7125 // Add the new return attributes.
7127 attrVec.push_back(AttributeWithIndex::get(0, RAttrs));
7129 AI = CS.arg_begin();
7130 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
7131 const Type *ParamTy = FT->getParamType(i);
7132 if ((*AI)->getType() == ParamTy) {
7133 Args.push_back(*AI);
7135 Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
7136 false, ParamTy, false);
7137 Args.push_back(Builder->CreateCast(opcode, *AI, ParamTy, "tmp"));
7140 // Add any parameter attributes.
7141 if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
7142 attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
7145 // If the function takes more arguments than the call was taking, add them
7147 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
7148 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
7150 // If we are removing arguments to the function, emit an obnoxious warning.
7151 if (FT->getNumParams() < NumActualArgs) {
7152 if (!FT->isVarArg()) {
7153 errs() << "WARNING: While resolving call to function '"
7154 << Callee->getName() << "' arguments were dropped!\n";
7156 // Add all of the arguments in their promoted form to the arg list.
7157 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
7158 const Type *PTy = getPromotedType((*AI)->getType());
7159 if (PTy != (*AI)->getType()) {
7160 // Must promote to pass through va_arg area!
7161 Instruction::CastOps opcode =
7162 CastInst::getCastOpcode(*AI, false, PTy, false);
7163 Args.push_back(Builder->CreateCast(opcode, *AI, PTy, "tmp"));
7165 Args.push_back(*AI);
7168 // Add any parameter attributes.
7169 if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
7170 attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
7175 if (Attributes FnAttrs = CallerPAL.getFnAttributes())
7176 attrVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
7178 if (NewRetTy->isVoidTy())
7179 Caller->setName(""); // Void type should not have a name.
7181 const AttrListPtr &NewCallerPAL = AttrListPtr::get(attrVec.begin(),
7185 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
7186 NC = InvokeInst::Create(Callee, II->getNormalDest(), II->getUnwindDest(),
7187 Args.begin(), Args.end(),
7188 Caller->getName(), Caller);
7189 cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
7190 cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
7192 NC = CallInst::Create(Callee, Args.begin(), Args.end(),
7193 Caller->getName(), Caller);
7194 CallInst *CI = cast<CallInst>(Caller);
7195 if (CI->isTailCall())
7196 cast<CallInst>(NC)->setTailCall();
7197 cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
7198 cast<CallInst>(NC)->setAttributes(NewCallerPAL);
7201 // Insert a cast of the return type as necessary.
7203 if (OldRetTy != NV->getType() && !Caller->use_empty()) {
7204 if (!NV->getType()->isVoidTy()) {
7205 Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
7207 NV = NC = CastInst::Create(opcode, NC, OldRetTy, "tmp");
7209 // If this is an invoke instruction, we should insert it after the first
7210 // non-phi, instruction in the normal successor block.
7211 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
7212 BasicBlock::iterator I = II->getNormalDest()->getFirstNonPHI();
7213 InsertNewInstBefore(NC, *I);
7215 // Otherwise, it's a call, just insert cast right after the call instr
7216 InsertNewInstBefore(NC, *Caller);
7218 Worklist.AddUsersToWorkList(*Caller);
7220 NV = UndefValue::get(Caller->getType());
7225 if (!Caller->use_empty())
7226 Caller->replaceAllUsesWith(NV);
7228 EraseInstFromFunction(*Caller);
7232 // transformCallThroughTrampoline - Turn a call to a function created by the
7233 // init_trampoline intrinsic into a direct call to the underlying function.
7235 Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) {
7236 Value *Callee = CS.getCalledValue();
7237 const PointerType *PTy = cast<PointerType>(Callee->getType());
7238 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
7239 const AttrListPtr &Attrs = CS.getAttributes();
7241 // If the call already has the 'nest' attribute somewhere then give up -
7242 // otherwise 'nest' would occur twice after splicing in the chain.
7243 if (Attrs.hasAttrSomewhere(Attribute::Nest))
7246 IntrinsicInst *Tramp =
7247 cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0));
7249 Function *NestF = cast<Function>(Tramp->getOperand(2)->stripPointerCasts());
7250 const PointerType *NestFPTy = cast<PointerType>(NestF->getType());
7251 const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
7253 const AttrListPtr &NestAttrs = NestF->getAttributes();
7254 if (!NestAttrs.isEmpty()) {
7255 unsigned NestIdx = 1;
7256 const Type *NestTy = 0;
7257 Attributes NestAttr = Attribute::None;
7259 // Look for a parameter marked with the 'nest' attribute.
7260 for (FunctionType::param_iterator I = NestFTy->param_begin(),
7261 E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
7262 if (NestAttrs.paramHasAttr(NestIdx, Attribute::Nest)) {
7263 // Record the parameter type and any other attributes.
7265 NestAttr = NestAttrs.getParamAttributes(NestIdx);
7270 Instruction *Caller = CS.getInstruction();
7271 std::vector<Value*> NewArgs;
7272 NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
7274 SmallVector<AttributeWithIndex, 8> NewAttrs;
7275 NewAttrs.reserve(Attrs.getNumSlots() + 1);
7277 // Insert the nest argument into the call argument list, which may
7278 // mean appending it. Likewise for attributes.
7280 // Add any result attributes.
7281 if (Attributes Attr = Attrs.getRetAttributes())
7282 NewAttrs.push_back(AttributeWithIndex::get(0, Attr));
7286 CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
7288 if (Idx == NestIdx) {
7289 // Add the chain argument and attributes.
7290 Value *NestVal = Tramp->getOperand(3);
7291 if (NestVal->getType() != NestTy)
7292 NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller);
7293 NewArgs.push_back(NestVal);
7294 NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr));
7300 // Add the original argument and attributes.
7301 NewArgs.push_back(*I);
7302 if (Attributes Attr = Attrs.getParamAttributes(Idx))
7304 (AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr));
7310 // Add any function attributes.
7311 if (Attributes Attr = Attrs.getFnAttributes())
7312 NewAttrs.push_back(AttributeWithIndex::get(~0, Attr));
7314 // The trampoline may have been bitcast to a bogus type (FTy).
7315 // Handle this by synthesizing a new function type, equal to FTy
7316 // with the chain parameter inserted.
7318 std::vector<const Type*> NewTypes;
7319 NewTypes.reserve(FTy->getNumParams()+1);
7321 // Insert the chain's type into the list of parameter types, which may
7322 // mean appending it.
7325 FunctionType::param_iterator I = FTy->param_begin(),
7326 E = FTy->param_end();
7330 // Add the chain's type.
7331 NewTypes.push_back(NestTy);
7336 // Add the original type.
7337 NewTypes.push_back(*I);
7343 // Replace the trampoline call with a direct call. Let the generic
7344 // code sort out any function type mismatches.
7345 FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes,
7347 Constant *NewCallee =
7348 NestF->getType() == PointerType::getUnqual(NewFTy) ?
7349 NestF : ConstantExpr::getBitCast(NestF,
7350 PointerType::getUnqual(NewFTy));
7351 const AttrListPtr &NewPAL = AttrListPtr::get(NewAttrs.begin(),
7354 Instruction *NewCaller;
7355 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
7356 NewCaller = InvokeInst::Create(NewCallee,
7357 II->getNormalDest(), II->getUnwindDest(),
7358 NewArgs.begin(), NewArgs.end(),
7359 Caller->getName(), Caller);
7360 cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
7361 cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
7363 NewCaller = CallInst::Create(NewCallee, NewArgs.begin(), NewArgs.end(),
7364 Caller->getName(), Caller);
7365 if (cast<CallInst>(Caller)->isTailCall())
7366 cast<CallInst>(NewCaller)->setTailCall();
7367 cast<CallInst>(NewCaller)->
7368 setCallingConv(cast<CallInst>(Caller)->getCallingConv());
7369 cast<CallInst>(NewCaller)->setAttributes(NewPAL);
7371 if (!Caller->getType()->isVoidTy())
7372 Caller->replaceAllUsesWith(NewCaller);
7373 Caller->eraseFromParent();
7374 Worklist.Remove(Caller);
7379 // Replace the trampoline call with a direct call. Since there is no 'nest'
7380 // parameter, there is no need to adjust the argument list. Let the generic
7381 // code sort out any function type mismatches.
7382 Constant *NewCallee =
7383 NestF->getType() == PTy ? NestF :
7384 ConstantExpr::getBitCast(NestF, PTy);
7385 CS.setCalledFunction(NewCallee);
7386 return CS.getInstruction();
7389 /// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(a,c)]
7390 /// and if a/b/c and the add's all have a single use, turn this into a phi
7391 /// and a single binop.
7392 Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
7393 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
7394 assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst));
7395 unsigned Opc = FirstInst->getOpcode();
7396 Value *LHSVal = FirstInst->getOperand(0);
7397 Value *RHSVal = FirstInst->getOperand(1);
7399 const Type *LHSType = LHSVal->getType();
7400 const Type *RHSType = RHSVal->getType();
7402 // Scan to see if all operands are the same opcode, and all have one use.
7403 for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
7404 Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
7405 if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
7406 // Verify type of the LHS matches so we don't fold cmp's of different
7407 // types or GEP's with different index types.
7408 I->getOperand(0)->getType() != LHSType ||
7409 I->getOperand(1)->getType() != RHSType)
7412 // If they are CmpInst instructions, check their predicates
7413 if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
7414 if (cast<CmpInst>(I)->getPredicate() !=
7415 cast<CmpInst>(FirstInst)->getPredicate())
7418 // Keep track of which operand needs a phi node.
7419 if (I->getOperand(0) != LHSVal) LHSVal = 0;
7420 if (I->getOperand(1) != RHSVal) RHSVal = 0;
7423 // If both LHS and RHS would need a PHI, don't do this transformation,
7424 // because it would increase the number of PHIs entering the block,
7425 // which leads to higher register pressure. This is especially
7426 // bad when the PHIs are in the header of a loop.
7427 if (!LHSVal && !RHSVal)
7430 // Otherwise, this is safe to transform!
7432 Value *InLHS = FirstInst->getOperand(0);
7433 Value *InRHS = FirstInst->getOperand(1);
7434 PHINode *NewLHS = 0, *NewRHS = 0;
7436 NewLHS = PHINode::Create(LHSType,
7437 FirstInst->getOperand(0)->getName() + ".pn");
7438 NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
7439 NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
7440 InsertNewInstBefore(NewLHS, PN);
7445 NewRHS = PHINode::Create(RHSType,
7446 FirstInst->getOperand(1)->getName() + ".pn");
7447 NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
7448 NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
7449 InsertNewInstBefore(NewRHS, PN);
7453 // Add all operands to the new PHIs.
7454 if (NewLHS || NewRHS) {
7455 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
7456 Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i));
7458 Value *NewInLHS = InInst->getOperand(0);
7459 NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
7462 Value *NewInRHS = InInst->getOperand(1);
7463 NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
7468 if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
7469 return BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
7470 CmpInst *CIOp = cast<CmpInst>(FirstInst);
7471 return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
7475 Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
7476 GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0));
7478 SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(),
7479 FirstInst->op_end());
7480 // This is true if all GEP bases are allocas and if all indices into them are
7482 bool AllBasePointersAreAllocas = true;
7484 // We don't want to replace this phi if the replacement would require
7485 // more than one phi, which leads to higher register pressure. This is
7486 // especially bad when the PHIs are in the header of a loop.
7487 bool NeededPhi = false;
7489 // Scan to see if all operands are the same opcode, and all have one use.
7490 for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
7491 GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
7492 if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() ||
7493 GEP->getNumOperands() != FirstInst->getNumOperands())
7496 // Keep track of whether or not all GEPs are of alloca pointers.
7497 if (AllBasePointersAreAllocas &&
7498 (!isa<AllocaInst>(GEP->getOperand(0)) ||
7499 !GEP->hasAllConstantIndices()))
7500 AllBasePointersAreAllocas = false;
7502 // Compare the operand lists.
7503 for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) {
7504 if (FirstInst->getOperand(op) == GEP->getOperand(op))
7507 // Don't merge two GEPs when two operands differ (introducing phi nodes)
7508 // if one of the PHIs has a constant for the index. The index may be
7509 // substantially cheaper to compute for the constants, so making it a
7510 // variable index could pessimize the path. This also handles the case
7511 // for struct indices, which must always be constant.
7512 if (isa<ConstantInt>(FirstInst->getOperand(op)) ||
7513 isa<ConstantInt>(GEP->getOperand(op)))
7516 if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType())
7519 // If we already needed a PHI for an earlier operand, and another operand
7520 // also requires a PHI, we'd be introducing more PHIs than we're
7521 // eliminating, which increases register pressure on entry to the PHI's
7526 FixedOperands[op] = 0; // Needs a PHI.
7531 // If all of the base pointers of the PHI'd GEPs are from allocas, don't
7532 // bother doing this transformation. At best, this will just save a bit of
7533 // offset calculation, but all the predecessors will have to materialize the
7534 // stack address into a register anyway. We'd actually rather *clone* the
7535 // load up into the predecessors so that we have a load of a gep of an alloca,
7536 // which can usually all be folded into the load.
7537 if (AllBasePointersAreAllocas)
7540 // Otherwise, this is safe to transform. Insert PHI nodes for each operand
7541 // that is variable.
7542 SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size());
7544 bool HasAnyPHIs = false;
7545 for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) {
7546 if (FixedOperands[i]) continue; // operand doesn't need a phi.
7547 Value *FirstOp = FirstInst->getOperand(i);
7548 PHINode *NewPN = PHINode::Create(FirstOp->getType(),
7549 FirstOp->getName()+".pn");
7550 InsertNewInstBefore(NewPN, PN);
7552 NewPN->reserveOperandSpace(e);
7553 NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0));
7554 OperandPhis[i] = NewPN;
7555 FixedOperands[i] = NewPN;
7560 // Add all operands to the new PHIs.
7562 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
7563 GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i));
7564 BasicBlock *InBB = PN.getIncomingBlock(i);
7566 for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op)
7567 if (PHINode *OpPhi = OperandPhis[op])
7568 OpPhi->addIncoming(InGEP->getOperand(op), InBB);
7572 Value *Base = FixedOperands[0];
7573 return cast<GEPOperator>(FirstInst)->isInBounds() ?
7574 GetElementPtrInst::CreateInBounds(Base, FixedOperands.begin()+1,
7575 FixedOperands.end()) :
7576 GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
7577 FixedOperands.end());
7581 /// isSafeAndProfitableToSinkLoad - Return true if we know that it is safe to
7582 /// sink the load out of the block that defines it. This means that it must be
7583 /// obvious the value of the load is not changed from the point of the load to
7584 /// the end of the block it is in.
7586 /// Finally, it is safe, but not profitable, to sink a load targetting a
7587 /// non-address-taken alloca. Doing so will cause us to not promote the alloca
7589 static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
7590 BasicBlock::iterator BBI = L, E = L->getParent()->end();
7592 for (++BBI; BBI != E; ++BBI)
7593 if (BBI->mayWriteToMemory())
7596 // Check for non-address taken alloca. If not address-taken already, it isn't
7597 // profitable to do this xform.
7598 if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
7599 bool isAddressTaken = false;
7600 for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
7602 if (isa<LoadInst>(UI)) continue;
7603 if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
7604 // If storing TO the alloca, then the address isn't taken.
7605 if (SI->getOperand(1) == AI) continue;
7607 isAddressTaken = true;
7611 if (!isAddressTaken && AI->isStaticAlloca())
7615 // If this load is a load from a GEP with a constant offset from an alloca,
7616 // then we don't want to sink it. In its present form, it will be
7617 // load [constant stack offset]. Sinking it will cause us to have to
7618 // materialize the stack addresses in each predecessor in a register only to
7619 // do a shared load from register in the successor.
7620 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0)))
7621 if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0)))
7622 if (AI->isStaticAlloca() && GEP->hasAllConstantIndices())
7628 Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
7629 LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0));
7631 // When processing loads, we need to propagate two bits of information to the
7632 // sunk load: whether it is volatile, and what its alignment is. We currently
7633 // don't sink loads when some have their alignment specified and some don't.
7634 // visitLoadInst will propagate an alignment onto the load when TD is around,
7635 // and if TD isn't around, we can't handle the mixed case.
7636 bool isVolatile = FirstLI->isVolatile();
7637 unsigned LoadAlignment = FirstLI->getAlignment();
7639 // We can't sink the load if the loaded value could be modified between the
7640 // load and the PHI.
7641 if (FirstLI->getParent() != PN.getIncomingBlock(0) ||
7642 !isSafeAndProfitableToSinkLoad(FirstLI))
7645 // If the PHI is of volatile loads and the load block has multiple
7646 // successors, sinking it would remove a load of the volatile value from
7647 // the path through the other successor.
7649 FirstLI->getParent()->getTerminator()->getNumSuccessors() != 1)
7652 // Check to see if all arguments are the same operation.
7653 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
7654 LoadInst *LI = dyn_cast<LoadInst>(PN.getIncomingValue(i));
7655 if (!LI || !LI->hasOneUse())
7658 // We can't sink the load if the loaded value could be modified between
7659 // the load and the PHI.
7660 if (LI->isVolatile() != isVolatile ||
7661 LI->getParent() != PN.getIncomingBlock(i) ||
7662 !isSafeAndProfitableToSinkLoad(LI))
7665 // If some of the loads have an alignment specified but not all of them,
7666 // we can't do the transformation.
7667 if ((LoadAlignment != 0) != (LI->getAlignment() != 0))
7670 LoadAlignment = std::min(LoadAlignment, LI->getAlignment());
7672 // If the PHI is of volatile loads and the load block has multiple
7673 // successors, sinking it would remove a load of the volatile value from
7674 // the path through the other successor.
7676 LI->getParent()->getTerminator()->getNumSuccessors() != 1)
7680 // Okay, they are all the same operation. Create a new PHI node of the
7681 // correct type, and PHI together all of the LHS's of the instructions.
7682 PHINode *NewPN = PHINode::Create(FirstLI->getOperand(0)->getType(),
7683 PN.getName()+".in");
7684 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
7686 Value *InVal = FirstLI->getOperand(0);
7687 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
7689 // Add all operands to the new PHI.
7690 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
7691 Value *NewInVal = cast<LoadInst>(PN.getIncomingValue(i))->getOperand(0);
7692 if (NewInVal != InVal)
7694 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
7699 // The new PHI unions all of the same values together. This is really
7700 // common, so we handle it intelligently here for compile-time speed.
7704 InsertNewInstBefore(NewPN, PN);
7708 // If this was a volatile load that we are merging, make sure to loop through
7709 // and mark all the input loads as non-volatile. If we don't do this, we will
7710 // insert a new volatile load and the old ones will not be deletable.
7712 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
7713 cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
7715 return new LoadInst(PhiVal, "", isVolatile, LoadAlignment);
7720 /// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
7721 /// operator and they all are only used by the PHI, PHI together their
7722 /// inputs, and do the operation once, to the result of the PHI.
7723 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
7724 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
7726 if (isa<GetElementPtrInst>(FirstInst))
7727 return FoldPHIArgGEPIntoPHI(PN);
7728 if (isa<LoadInst>(FirstInst))
7729 return FoldPHIArgLoadIntoPHI(PN);
7731 // Scan the instruction, looking for input operations that can be folded away.
7732 // If all input operands to the phi are the same instruction (e.g. a cast from
7733 // the same type or "+42") we can pull the operation through the PHI, reducing
7734 // code size and simplifying code.
7735 Constant *ConstantOp = 0;
7736 const Type *CastSrcTy = 0;
7738 if (isa<CastInst>(FirstInst)) {
7739 CastSrcTy = FirstInst->getOperand(0)->getType();
7741 // Be careful about transforming integer PHIs. We don't want to pessimize
7742 // the code by turning an i32 into an i1293.
7743 if (isa<IntegerType>(PN.getType()) && isa<IntegerType>(CastSrcTy)) {
7744 if (!ShouldChangeType(PN.getType(), CastSrcTy, TD))
7747 } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
7748 // Can fold binop, compare or shift here if the RHS is a constant,
7749 // otherwise call FoldPHIArgBinOpIntoPHI.
7750 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
7751 if (ConstantOp == 0)
7752 return FoldPHIArgBinOpIntoPHI(PN);
7754 return 0; // Cannot fold this operation.
7757 // Check to see if all arguments are the same operation.
7758 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
7759 Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
7760 if (I == 0 || !I->hasOneUse() || !I->isSameOperationAs(FirstInst))
7763 if (I->getOperand(0)->getType() != CastSrcTy)
7764 return 0; // Cast operation must match.
7765 } else if (I->getOperand(1) != ConstantOp) {
7770 // Okay, they are all the same operation. Create a new PHI node of the
7771 // correct type, and PHI together all of the LHS's of the instructions.
7772 PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(),
7773 PN.getName()+".in");
7774 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
7776 Value *InVal = FirstInst->getOperand(0);
7777 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
7779 // Add all operands to the new PHI.
7780 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
7781 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
7782 if (NewInVal != InVal)
7784 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
7789 // The new PHI unions all of the same values together. This is really
7790 // common, so we handle it intelligently here for compile-time speed.
7794 InsertNewInstBefore(NewPN, PN);
7798 // Insert and return the new operation.
7799 if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst))
7800 return CastInst::Create(FirstCI->getOpcode(), PhiVal, PN.getType());
7802 if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
7803 return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
7805 CmpInst *CIOp = cast<CmpInst>(FirstInst);
7806 return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
7807 PhiVal, ConstantOp);
7810 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
7812 static bool DeadPHICycle(PHINode *PN,
7813 SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
7814 if (PN->use_empty()) return true;
7815 if (!PN->hasOneUse()) return false;
7817 // Remember this node, and if we find the cycle, return.
7818 if (!PotentiallyDeadPHIs.insert(PN))
7821 // Don't scan crazily complex things.
7822 if (PotentiallyDeadPHIs.size() == 16)
7825 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
7826 return DeadPHICycle(PU, PotentiallyDeadPHIs);
7831 /// PHIsEqualValue - Return true if this phi node is always equal to
7832 /// NonPhiInVal. This happens with mutually cyclic phi nodes like:
7833 /// z = some value; x = phi (y, z); y = phi (x, z)
7834 static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
7835 SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
7836 // See if we already saw this PHI node.
7837 if (!ValueEqualPHIs.insert(PN))
7840 // Don't scan crazily complex things.
7841 if (ValueEqualPHIs.size() == 16)
7844 // Scan the operands to see if they are either phi nodes or are equal to
7846 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
7847 Value *Op = PN->getIncomingValue(i);
7848 if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
7849 if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
7851 } else if (Op != NonPhiInVal)
7860 struct PHIUsageRecord {
7861 unsigned PHIId; // The ID # of the PHI (something determinstic to sort on)
7862 unsigned Shift; // The amount shifted.
7863 Instruction *Inst; // The trunc instruction.
7865 PHIUsageRecord(unsigned pn, unsigned Sh, Instruction *User)
7866 : PHIId(pn), Shift(Sh), Inst(User) {}
7868 bool operator<(const PHIUsageRecord &RHS) const {
7869 if (PHIId < RHS.PHIId) return true;
7870 if (PHIId > RHS.PHIId) return false;
7871 if (Shift < RHS.Shift) return true;
7872 if (Shift > RHS.Shift) return false;
7873 return Inst->getType()->getPrimitiveSizeInBits() <
7874 RHS.Inst->getType()->getPrimitiveSizeInBits();
7878 struct LoweredPHIRecord {
7879 PHINode *PN; // The PHI that was lowered.
7880 unsigned Shift; // The amount shifted.
7881 unsigned Width; // The width extracted.
7883 LoweredPHIRecord(PHINode *pn, unsigned Sh, const Type *Ty)
7884 : PN(pn), Shift(Sh), Width(Ty->getPrimitiveSizeInBits()) {}
7886 // Ctor form used by DenseMap.
7887 LoweredPHIRecord(PHINode *pn, unsigned Sh)
7888 : PN(pn), Shift(Sh), Width(0) {}
7894 struct DenseMapInfo<LoweredPHIRecord> {
7895 static inline LoweredPHIRecord getEmptyKey() {
7896 return LoweredPHIRecord(0, 0);
7898 static inline LoweredPHIRecord getTombstoneKey() {
7899 return LoweredPHIRecord(0, 1);
7901 static unsigned getHashValue(const LoweredPHIRecord &Val) {
7902 return DenseMapInfo<PHINode*>::getHashValue(Val.PN) ^ (Val.Shift>>3) ^
7905 static bool isEqual(const LoweredPHIRecord &LHS,
7906 const LoweredPHIRecord &RHS) {
7907 return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift &&
7908 LHS.Width == RHS.Width;
7912 struct isPodLike<LoweredPHIRecord> { static const bool value = true; };
7916 /// SliceUpIllegalIntegerPHI - This is an integer PHI and we know that it has an
7917 /// illegal type: see if it is only used by trunc or trunc(lshr) operations. If
7918 /// so, we split the PHI into the various pieces being extracted. This sort of
7919 /// thing is introduced when SROA promotes an aggregate to large integer values.
7921 /// TODO: The user of the trunc may be an bitcast to float/double/vector or an
7922 /// inttoptr. We should produce new PHIs in the right type.
7924 Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
7925 // PHIUsers - Keep track of all of the truncated values extracted from a set
7926 // of PHIs, along with their offset. These are the things we want to rewrite.
7927 SmallVector<PHIUsageRecord, 16> PHIUsers;
7929 // PHIs are often mutually cyclic, so we keep track of a whole set of PHI
7930 // nodes which are extracted from. PHIsToSlice is a set we use to avoid
7931 // revisiting PHIs, PHIsInspected is a ordered list of PHIs that we need to
7932 // check the uses of (to ensure they are all extracts).
7933 SmallVector<PHINode*, 8> PHIsToSlice;
7934 SmallPtrSet<PHINode*, 8> PHIsInspected;
7936 PHIsToSlice.push_back(&FirstPhi);
7937 PHIsInspected.insert(&FirstPhi);
7939 for (unsigned PHIId = 0; PHIId != PHIsToSlice.size(); ++PHIId) {
7940 PHINode *PN = PHIsToSlice[PHIId];
7942 // Scan the input list of the PHI. If any input is an invoke, and if the
7943 // input is defined in the predecessor, then we won't be split the critical
7944 // edge which is required to insert a truncate. Because of this, we have to
7946 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
7947 InvokeInst *II = dyn_cast<InvokeInst>(PN->getIncomingValue(i));
7948 if (II == 0) continue;
7949 if (II->getParent() != PN->getIncomingBlock(i))
7952 // If we have a phi, and if it's directly in the predecessor, then we have
7953 // a critical edge where we need to put the truncate. Since we can't
7954 // split the edge in instcombine, we have to bail out.
7959 for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
7961 Instruction *User = cast<Instruction>(*UI);
7963 // If the user is a PHI, inspect its uses recursively.
7964 if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
7965 if (PHIsInspected.insert(UserPN))
7966 PHIsToSlice.push_back(UserPN);
7970 // Truncates are always ok.
7971 if (isa<TruncInst>(User)) {
7972 PHIUsers.push_back(PHIUsageRecord(PHIId, 0, User));
7976 // Otherwise it must be a lshr which can only be used by one trunc.
7977 if (User->getOpcode() != Instruction::LShr ||
7978 !User->hasOneUse() || !isa<TruncInst>(User->use_back()) ||
7979 !isa<ConstantInt>(User->getOperand(1)))
7982 unsigned Shift = cast<ConstantInt>(User->getOperand(1))->getZExtValue();
7983 PHIUsers.push_back(PHIUsageRecord(PHIId, Shift, User->use_back()));
7987 // If we have no users, they must be all self uses, just nuke the PHI.
7988 if (PHIUsers.empty())
7989 return ReplaceInstUsesWith(FirstPhi, UndefValue::get(FirstPhi.getType()));
7991 // If this phi node is transformable, create new PHIs for all the pieces
7992 // extracted out of it. First, sort the users by their offset and size.
7993 array_pod_sort(PHIUsers.begin(), PHIUsers.end());
7995 DEBUG(errs() << "SLICING UP PHI: " << FirstPhi << '\n';
7996 for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
7997 errs() << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] <<'\n';
8000 // PredValues - This is a temporary used when rewriting PHI nodes. It is
8001 // hoisted out here to avoid construction/destruction thrashing.
8002 DenseMap<BasicBlock*, Value*> PredValues;
8004 // ExtractedVals - Each new PHI we introduce is saved here so we don't
8005 // introduce redundant PHIs.
8006 DenseMap<LoweredPHIRecord, PHINode*> ExtractedVals;
8008 for (unsigned UserI = 0, UserE = PHIUsers.size(); UserI != UserE; ++UserI) {
8009 unsigned PHIId = PHIUsers[UserI].PHIId;
8010 PHINode *PN = PHIsToSlice[PHIId];
8011 unsigned Offset = PHIUsers[UserI].Shift;
8012 const Type *Ty = PHIUsers[UserI].Inst->getType();
8016 // If we've already lowered a user like this, reuse the previously lowered
8018 if ((EltPHI = ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)]) == 0) {
8020 // Otherwise, Create the new PHI node for this user.
8021 EltPHI = PHINode::Create(Ty, PN->getName()+".off"+Twine(Offset), PN);
8022 assert(EltPHI->getType() != PN->getType() &&
8023 "Truncate didn't shrink phi?");
8025 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
8026 BasicBlock *Pred = PN->getIncomingBlock(i);
8027 Value *&PredVal = PredValues[Pred];
8029 // If we already have a value for this predecessor, reuse it.
8031 EltPHI->addIncoming(PredVal, Pred);
8035 // Handle the PHI self-reuse case.
8036 Value *InVal = PN->getIncomingValue(i);
8039 EltPHI->addIncoming(PredVal, Pred);
8043 if (PHINode *InPHI = dyn_cast<PHINode>(PN)) {
8044 // If the incoming value was a PHI, and if it was one of the PHIs we
8045 // already rewrote it, just use the lowered value.
8046 if (Value *Res = ExtractedVals[LoweredPHIRecord(InPHI, Offset, Ty)]) {
8048 EltPHI->addIncoming(PredVal, Pred);
8053 // Otherwise, do an extract in the predecessor.
8054 Builder->SetInsertPoint(Pred, Pred->getTerminator());
8057 Res = Builder->CreateLShr(Res, ConstantInt::get(InVal->getType(),
8058 Offset), "extract");
8059 Res = Builder->CreateTrunc(Res, Ty, "extract.t");
8061 EltPHI->addIncoming(Res, Pred);
8063 // If the incoming value was a PHI, and if it was one of the PHIs we are
8064 // rewriting, we will ultimately delete the code we inserted. This
8065 // means we need to revisit that PHI to make sure we extract out the
8067 if (PHINode *OldInVal = dyn_cast<PHINode>(PN->getIncomingValue(i)))
8068 if (PHIsInspected.count(OldInVal)) {
8069 unsigned RefPHIId = std::find(PHIsToSlice.begin(),PHIsToSlice.end(),
8070 OldInVal)-PHIsToSlice.begin();
8071 PHIUsers.push_back(PHIUsageRecord(RefPHIId, Offset,
8072 cast<Instruction>(Res)));
8078 DEBUG(errs() << " Made element PHI for offset " << Offset << ": "
8079 << *EltPHI << '\n');
8080 ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)] = EltPHI;
8083 // Replace the use of this piece with the PHI node.
8084 ReplaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI);
8087 // Replace all the remaining uses of the PHI nodes (self uses and the lshrs)
8089 Value *Undef = UndefValue::get(FirstPhi.getType());
8090 for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
8091 ReplaceInstUsesWith(*PHIsToSlice[i], Undef);
8092 return ReplaceInstUsesWith(FirstPhi, Undef);
8095 // PHINode simplification
8097 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
8098 // If LCSSA is around, don't mess with Phi nodes
8099 if (MustPreserveLCSSA) return 0;
8101 if (Value *V = PN.hasConstantValue())
8102 return ReplaceInstUsesWith(PN, V);
8104 // If all PHI operands are the same operation, pull them through the PHI,
8105 // reducing code size.
8106 if (isa<Instruction>(PN.getIncomingValue(0)) &&
8107 isa<Instruction>(PN.getIncomingValue(1)) &&
8108 cast<Instruction>(PN.getIncomingValue(0))->getOpcode() ==
8109 cast<Instruction>(PN.getIncomingValue(1))->getOpcode() &&
8110 // FIXME: The hasOneUse check will fail for PHIs that use the value more
8111 // than themselves more than once.
8112 PN.getIncomingValue(0)->hasOneUse())
8113 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
8116 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
8117 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
8118 // PHI)... break the cycle.
8119 if (PN.hasOneUse()) {
8120 Instruction *PHIUser = cast<Instruction>(PN.use_back());
8121 if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
8122 SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
8123 PotentiallyDeadPHIs.insert(&PN);
8124 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
8125 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
8128 // If this phi has a single use, and if that use just computes a value for
8129 // the next iteration of a loop, delete the phi. This occurs with unused
8130 // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
8131 // common case here is good because the only other things that catch this
8132 // are induction variable analysis (sometimes) and ADCE, which is only run
8134 if (PHIUser->hasOneUse() &&
8135 (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
8136 PHIUser->use_back() == &PN) {
8137 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
8141 // We sometimes end up with phi cycles that non-obviously end up being the
8142 // same value, for example:
8143 // z = some value; x = phi (y, z); y = phi (x, z)
8144 // where the phi nodes don't necessarily need to be in the same block. Do a
8145 // quick check to see if the PHI node only contains a single non-phi value, if
8146 // so, scan to see if the phi cycle is actually equal to that value.
8148 unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues();
8149 // Scan for the first non-phi operand.
8150 while (InValNo != NumOperandVals &&
8151 isa<PHINode>(PN.getIncomingValue(InValNo)))
8154 if (InValNo != NumOperandVals) {
8155 Value *NonPhiInVal = PN.getOperand(InValNo);
8157 // Scan the rest of the operands to see if there are any conflicts, if so
8158 // there is no need to recursively scan other phis.
8159 for (++InValNo; InValNo != NumOperandVals; ++InValNo) {
8160 Value *OpVal = PN.getIncomingValue(InValNo);
8161 if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
8165 // If we scanned over all operands, then we have one unique value plus
8166 // phi values. Scan PHI nodes to see if they all merge in each other or
8168 if (InValNo == NumOperandVals) {
8169 SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
8170 if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
8171 return ReplaceInstUsesWith(PN, NonPhiInVal);
8176 // If there are multiple PHIs, sort their operands so that they all list
8177 // the blocks in the same order. This will help identical PHIs be eliminated
8178 // by other passes. Other passes shouldn't depend on this for correctness
8180 PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin());
8182 for (unsigned i = 0, e = FirstPN->getNumIncomingValues(); i != e; ++i) {
8183 BasicBlock *BBA = PN.getIncomingBlock(i);
8184 BasicBlock *BBB = FirstPN->getIncomingBlock(i);
8186 Value *VA = PN.getIncomingValue(i);
8187 unsigned j = PN.getBasicBlockIndex(BBB);
8188 Value *VB = PN.getIncomingValue(j);
8189 PN.setIncomingBlock(i, BBB);
8190 PN.setIncomingValue(i, VB);
8191 PN.setIncomingBlock(j, BBA);
8192 PN.setIncomingValue(j, VA);
8193 // NOTE: Instcombine normally would want us to "return &PN" if we
8194 // modified any of the operands of an instruction. However, since we
8195 // aren't adding or removing uses (just rearranging them) we don't do
8196 // this in this case.
8200 // If this is an integer PHI and we know that it has an illegal type, see if
8201 // it is only used by trunc or trunc(lshr) operations. If so, we split the
8202 // PHI into the various pieces being extracted. This sort of thing is
8203 // introduced when SROA promotes an aggregate to a single large integer type.
8204 if (isa<IntegerType>(PN.getType()) && TD &&
8205 !TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits()))
8206 if (Instruction *Res = SliceUpIllegalIntegerPHI(PN))
8212 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
8213 SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
8215 if (Value *V = SimplifyGEPInst(&Ops[0], Ops.size(), TD))
8216 return ReplaceInstUsesWith(GEP, V);
8218 Value *PtrOp = GEP.getOperand(0);
8220 if (isa<UndefValue>(GEP.getOperand(0)))
8221 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
8223 // Eliminate unneeded casts for indices.
8225 bool MadeChange = false;
8226 unsigned PtrSize = TD->getPointerSizeInBits();
8228 gep_type_iterator GTI = gep_type_begin(GEP);
8229 for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end();
8230 I != E; ++I, ++GTI) {
8231 if (!isa<SequentialType>(*GTI)) continue;
8233 // If we are using a wider index than needed for this platform, shrink it
8234 // to what we need. If narrower, sign-extend it to what we need. This
8235 // explicit cast can make subsequent optimizations more obvious.
8236 unsigned OpBits = cast<IntegerType>((*I)->getType())->getBitWidth();
8237 if (OpBits == PtrSize)
8240 *I = Builder->CreateIntCast(*I, TD->getIntPtrType(GEP.getContext()),true);
8243 if (MadeChange) return &GEP;
8246 // Combine Indices - If the source pointer to this getelementptr instruction
8247 // is a getelementptr instruction, combine the indices of the two
8248 // getelementptr instructions into a single instruction.
8250 if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
8251 // Note that if our source is a gep chain itself that we wait for that
8252 // chain to be resolved before we perform this transformation. This
8253 // avoids us creating a TON of code in some cases.
8255 if (GetElementPtrInst *SrcGEP =
8256 dyn_cast<GetElementPtrInst>(Src->getOperand(0)))
8257 if (SrcGEP->getNumOperands() == 2)
8258 return 0; // Wait until our source is folded to completion.
8260 SmallVector<Value*, 8> Indices;
8262 // Find out whether the last index in the source GEP is a sequential idx.
8263 bool EndsWithSequential = false;
8264 for (gep_type_iterator I = gep_type_begin(*Src), E = gep_type_end(*Src);
8266 EndsWithSequential = !isa<StructType>(*I);
8268 // Can we combine the two pointer arithmetics offsets?
8269 if (EndsWithSequential) {
8270 // Replace: gep (gep %P, long B), long A, ...
8271 // With: T = long A+B; gep %P, T, ...
8274 Value *SO1 = Src->getOperand(Src->getNumOperands()-1);
8275 Value *GO1 = GEP.getOperand(1);
8276 if (SO1 == Constant::getNullValue(SO1->getType())) {
8278 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
8281 // If they aren't the same type, then the input hasn't been processed
8282 // by the loop above yet (which canonicalizes sequential index types to
8283 // intptr_t). Just avoid transforming this until the input has been
8285 if (SO1->getType() != GO1->getType())
8287 Sum = Builder->CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
8290 // Update the GEP in place if possible.
8291 if (Src->getNumOperands() == 2) {
8292 GEP.setOperand(0, Src->getOperand(0));
8293 GEP.setOperand(1, Sum);
8296 Indices.append(Src->op_begin()+1, Src->op_end()-1);
8297 Indices.push_back(Sum);
8298 Indices.append(GEP.op_begin()+2, GEP.op_end());
8299 } else if (isa<Constant>(*GEP.idx_begin()) &&
8300 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
8301 Src->getNumOperands() != 1) {
8302 // Otherwise we can do the fold if the first index of the GEP is a zero
8303 Indices.append(Src->op_begin()+1, Src->op_end());
8304 Indices.append(GEP.idx_begin()+1, GEP.idx_end());
8307 if (!Indices.empty())
8308 return (cast<GEPOperator>(&GEP)->isInBounds() &&
8309 Src->isInBounds()) ?
8310 GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices.begin(),
8311 Indices.end(), GEP.getName()) :
8312 GetElementPtrInst::Create(Src->getOperand(0), Indices.begin(),
8313 Indices.end(), GEP.getName());
8316 // Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
8317 if (Value *X = getBitCastOperand(PtrOp)) {
8318 assert(isa<PointerType>(X->getType()) && "Must be cast from pointer");
8320 // If the input bitcast is actually "bitcast(bitcast(x))", then we don't
8321 // want to change the gep until the bitcasts are eliminated.
8322 if (getBitCastOperand(X)) {
8323 Worklist.AddValue(PtrOp);
8327 bool HasZeroPointerIndex = false;
8328 if (ConstantInt *C = dyn_cast<ConstantInt>(GEP.getOperand(1)))
8329 HasZeroPointerIndex = C->isZero();
8331 // Transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
8332 // into : GEP [10 x i8]* X, i32 0, ...
8334 // Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
8335 // into : GEP i8* X, ...
8337 // This occurs when the program declares an array extern like "int X[];"
8338 if (HasZeroPointerIndex) {
8339 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
8340 const PointerType *XTy = cast<PointerType>(X->getType());
8341 if (const ArrayType *CATy =
8342 dyn_cast<ArrayType>(CPTy->getElementType())) {
8343 // GEP (bitcast i8* X to [0 x i8]*), i32 0, ... ?
8344 if (CATy->getElementType() == XTy->getElementType()) {
8345 // -> GEP i8* X, ...
8346 SmallVector<Value*, 8> Indices(GEP.idx_begin()+1, GEP.idx_end());
8347 return cast<GEPOperator>(&GEP)->isInBounds() ?
8348 GetElementPtrInst::CreateInBounds(X, Indices.begin(), Indices.end(),
8350 GetElementPtrInst::Create(X, Indices.begin(), Indices.end(),
8354 if (const ArrayType *XATy = dyn_cast<ArrayType>(XTy->getElementType())){
8355 // GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ?
8356 if (CATy->getElementType() == XATy->getElementType()) {
8357 // -> GEP [10 x i8]* X, i32 0, ...
8358 // At this point, we know that the cast source type is a pointer
8359 // to an array of the same type as the destination pointer
8360 // array. Because the array type is never stepped over (there
8361 // is a leading zero) we can fold the cast into this GEP.
8362 GEP.setOperand(0, X);
8367 } else if (GEP.getNumOperands() == 2) {
8368 // Transform things like:
8369 // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
8370 // into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
8371 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
8372 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
8373 if (TD && isa<ArrayType>(SrcElTy) &&
8374 TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
8375 TD->getTypeAllocSize(ResElTy)) {
8377 Idx[0] = Constant::getNullValue(Type::getInt32Ty(GEP.getContext()));
8378 Idx[1] = GEP.getOperand(1);
8379 Value *NewGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
8380 Builder->CreateInBoundsGEP(X, Idx, Idx + 2, GEP.getName()) :
8381 Builder->CreateGEP(X, Idx, Idx + 2, GEP.getName());
8382 // V and GEP are both pointer types --> BitCast
8383 return new BitCastInst(NewGEP, GEP.getType());
8386 // Transform things like:
8387 // getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
8388 // (where tmp = 8*tmp2) into:
8389 // getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
8391 if (TD && isa<ArrayType>(SrcElTy) &&
8392 ResElTy == Type::getInt8Ty(GEP.getContext())) {
8393 uint64_t ArrayEltSize =
8394 TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType());
8396 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
8397 // allow either a mul, shift, or constant here.
8399 ConstantInt *Scale = 0;
8400 if (ArrayEltSize == 1) {
8401 NewIdx = GEP.getOperand(1);
8402 Scale = ConstantInt::get(cast<IntegerType>(NewIdx->getType()), 1);
8403 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
8404 NewIdx = ConstantInt::get(CI->getType(), 1);
8406 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
8407 if (Inst->getOpcode() == Instruction::Shl &&
8408 isa<ConstantInt>(Inst->getOperand(1))) {
8409 ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
8410 uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
8411 Scale = ConstantInt::get(cast<IntegerType>(Inst->getType()),
8413 NewIdx = Inst->getOperand(0);
8414 } else if (Inst->getOpcode() == Instruction::Mul &&
8415 isa<ConstantInt>(Inst->getOperand(1))) {
8416 Scale = cast<ConstantInt>(Inst->getOperand(1));
8417 NewIdx = Inst->getOperand(0);
8421 // If the index will be to exactly the right offset with the scale taken
8422 // out, perform the transformation. Note, we don't know whether Scale is
8423 // signed or not. We'll use unsigned version of division/modulo
8424 // operation after making sure Scale doesn't have the sign bit set.
8425 if (ArrayEltSize && Scale && Scale->getSExtValue() >= 0LL &&
8426 Scale->getZExtValue() % ArrayEltSize == 0) {
8427 Scale = ConstantInt::get(Scale->getType(),
8428 Scale->getZExtValue() / ArrayEltSize);
8429 if (Scale->getZExtValue() != 1) {
8430 Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
8432 NewIdx = Builder->CreateMul(NewIdx, C, "idxscale");
8435 // Insert the new GEP instruction.
8437 Idx[0] = Constant::getNullValue(Type::getInt32Ty(GEP.getContext()));
8439 Value *NewGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
8440 Builder->CreateInBoundsGEP(X, Idx, Idx + 2, GEP.getName()) :
8441 Builder->CreateGEP(X, Idx, Idx + 2, GEP.getName());
8442 // The NewGEP must be pointer typed, so must the old one -> BitCast
8443 return new BitCastInst(NewGEP, GEP.getType());
8449 /// See if we can simplify:
8450 /// X = bitcast A* to B*
8451 /// Y = gep X, <...constant indices...>
8452 /// into a gep of the original struct. This is important for SROA and alias
8453 /// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
8454 if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
8456 !isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
8457 // Determine how much the GEP moves the pointer. We are guaranteed to get
8458 // a constant back from EmitGEPOffset.
8459 ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP));
8460 int64_t Offset = OffsetV->getSExtValue();
8462 // If this GEP instruction doesn't move the pointer, just replace the GEP
8463 // with a bitcast of the real input to the dest type.
8465 // If the bitcast is of an allocation, and the allocation will be
8466 // converted to match the type of the cast, don't touch this.
8467 if (isa<AllocaInst>(BCI->getOperand(0)) ||
8468 isMalloc(BCI->getOperand(0))) {
8469 // See if the bitcast simplifies, if so, don't nuke this GEP yet.
8470 if (Instruction *I = visitBitCast(*BCI)) {
8473 BCI->getParent()->getInstList().insert(BCI, I);
8474 ReplaceInstUsesWith(*BCI, I);
8479 return new BitCastInst(BCI->getOperand(0), GEP.getType());
8482 // Otherwise, if the offset is non-zero, we need to find out if there is a
8483 // field at Offset in 'A's type. If so, we can pull the cast through the
8485 SmallVector<Value*, 8> NewIndices;
8487 cast<PointerType>(BCI->getOperand(0)->getType())->getElementType();
8488 if (FindElementAtOffset(InTy, Offset, NewIndices, TD)) {
8489 Value *NGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
8490 Builder->CreateInBoundsGEP(BCI->getOperand(0), NewIndices.begin(),
8492 Builder->CreateGEP(BCI->getOperand(0), NewIndices.begin(),
8495 if (NGEP->getType() == GEP.getType())
8496 return ReplaceInstUsesWith(GEP, NGEP);
8497 NGEP->takeName(&GEP);
8498 return new BitCastInst(NGEP, GEP.getType());
8506 Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
8507 // Convert: alloca Ty, C - where C is a constant != 1 into: alloca [C x Ty], 1
8508 if (AI.isArrayAllocation()) { // Check C != 1
8509 if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
8511 ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
8512 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
8513 AllocaInst *New = Builder->CreateAlloca(NewTy, 0, AI.getName());
8514 New->setAlignment(AI.getAlignment());
8516 // Scan to the end of the allocation instructions, to skip over a block of
8517 // allocas if possible...also skip interleaved debug info
8519 BasicBlock::iterator It = New;
8520 while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It)) ++It;
8522 // Now that I is pointing to the first non-allocation-inst in the block,
8523 // insert our getelementptr instruction...
8525 Value *NullIdx =Constant::getNullValue(Type::getInt32Ty(AI.getContext()));
8529 Value *V = GetElementPtrInst::CreateInBounds(New, Idx, Idx + 2,
8530 New->getName()+".sub", It);
8532 // Now make everything use the getelementptr instead of the original
8534 return ReplaceInstUsesWith(AI, V);
8535 } else if (isa<UndefValue>(AI.getArraySize())) {
8536 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
8540 if (TD && isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized()) {
8541 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
8542 // Note that we only do this for alloca's, because malloc should allocate
8543 // and return a unique pointer, even for a zero byte allocation.
8544 if (TD->getTypeAllocSize(AI.getAllocatedType()) == 0)
8545 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
8547 // If the alignment is 0 (unspecified), assign it the preferred alignment.
8548 if (AI.getAlignment() == 0)
8549 AI.setAlignment(TD->getPrefTypeAlignment(AI.getAllocatedType()));
8555 Instruction *InstCombiner::visitFree(Instruction &FI) {
8556 Value *Op = FI.getOperand(1);
8558 // free undef -> unreachable.
8559 if (isa<UndefValue>(Op)) {
8560 // Insert a new store to null because we cannot modify the CFG here.
8561 new StoreInst(ConstantInt::getTrue(FI.getContext()),
8562 UndefValue::get(Type::getInt1PtrTy(FI.getContext())), &FI);
8563 return EraseInstFromFunction(FI);
8566 // If we have 'free null' delete the instruction. This can happen in stl code
8567 // when lots of inlining happens.
8568 if (isa<ConstantPointerNull>(Op))
8569 return EraseInstFromFunction(FI);
8571 // If we have a malloc call whose only use is a free call, delete both.
8573 if (CallInst* CI = extractMallocCallFromBitCast(Op)) {
8574 if (Op->hasOneUse() && CI->hasOneUse()) {
8575 EraseInstFromFunction(FI);
8576 EraseInstFromFunction(*CI);
8577 return EraseInstFromFunction(*cast<Instruction>(Op));
8580 // Op is a call to malloc
8581 if (Op->hasOneUse()) {
8582 EraseInstFromFunction(FI);
8583 return EraseInstFromFunction(*cast<Instruction>(Op));
8591 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
8592 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
8593 const TargetData *TD) {
8594 User *CI = cast<User>(LI.getOperand(0));
8595 Value *CastOp = CI->getOperand(0);
8597 const PointerType *DestTy = cast<PointerType>(CI->getType());
8598 const Type *DestPTy = DestTy->getElementType();
8599 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
8601 // If the address spaces don't match, don't eliminate the cast.
8602 if (DestTy->getAddressSpace() != SrcTy->getAddressSpace())
8605 const Type *SrcPTy = SrcTy->getElementType();
8607 if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
8608 isa<VectorType>(DestPTy)) {
8609 // If the source is an array, the code below will not succeed. Check to
8610 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
8612 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
8613 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
8614 if (ASrcTy->getNumElements() != 0) {
8616 Idxs[0] = Constant::getNullValue(Type::getInt32Ty(LI.getContext()));
8618 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
8619 SrcTy = cast<PointerType>(CastOp->getType());
8620 SrcPTy = SrcTy->getElementType();
8623 if (IC.getTargetData() &&
8624 (SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
8625 isa<VectorType>(SrcPTy)) &&
8626 // Do not allow turning this into a load of an integer, which is then
8627 // casted to a pointer, this pessimizes pointer analysis a lot.
8628 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
8629 IC.getTargetData()->getTypeSizeInBits(SrcPTy) ==
8630 IC.getTargetData()->getTypeSizeInBits(DestPTy)) {
8632 // Okay, we are casting from one integer or pointer type to another of
8633 // the same size. Instead of casting the pointer before the load, cast
8634 // the result of the loaded value.
8636 IC.Builder->CreateLoad(CastOp, LI.isVolatile(), CI->getName());
8637 // Now cast the result of the load.
8638 return new BitCastInst(NewLoad, LI.getType());
8645 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
8646 Value *Op = LI.getOperand(0);
8648 // Attempt to improve the alignment.
8650 unsigned KnownAlign =
8651 GetOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()));
8653 (LI.getAlignment() == 0 ? TD->getABITypeAlignment(LI.getType()) :
8655 LI.setAlignment(KnownAlign);
8658 // load (cast X) --> cast (load X) iff safe.
8659 if (isa<CastInst>(Op))
8660 if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
8663 // None of the following transforms are legal for volatile loads.
8664 if (LI.isVolatile()) return 0;
8666 // Do really simple store-to-load forwarding and load CSE, to catch cases
8667 // where there are several consequtive memory accesses to the same location,
8668 // separated by a few arithmetic operations.
8669 BasicBlock::iterator BBI = &LI;
8670 if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI,6))
8671 return ReplaceInstUsesWith(LI, AvailableVal);
8673 // load(gep null, ...) -> unreachable
8674 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
8675 const Value *GEPI0 = GEPI->getOperand(0);
8676 // TODO: Consider a target hook for valid address spaces for this xform.
8677 if (isa<ConstantPointerNull>(GEPI0) && GEPI->getPointerAddressSpace() == 0){
8678 // Insert a new store to null instruction before the load to indicate
8679 // that this code is not reachable. We do this instead of inserting
8680 // an unreachable instruction directly because we cannot modify the
8682 new StoreInst(UndefValue::get(LI.getType()),
8683 Constant::getNullValue(Op->getType()), &LI);
8684 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
8688 // load null/undef -> unreachable
8689 // TODO: Consider a target hook for valid address spaces for this xform.
8690 if (isa<UndefValue>(Op) ||
8691 (isa<ConstantPointerNull>(Op) && LI.getPointerAddressSpace() == 0)) {
8692 // Insert a new store to null instruction before the load to indicate that
8693 // this code is not reachable. We do this instead of inserting an
8694 // unreachable instruction directly because we cannot modify the CFG.
8695 new StoreInst(UndefValue::get(LI.getType()),
8696 Constant::getNullValue(Op->getType()), &LI);
8697 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
8700 // Instcombine load (constantexpr_cast global) -> cast (load global)
8701 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
8703 if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
8706 if (Op->hasOneUse()) {
8707 // Change select and PHI nodes to select values instead of addresses: this
8708 // helps alias analysis out a lot, allows many others simplifications, and
8709 // exposes redundancy in the code.
8711 // Note that we cannot do the transformation unless we know that the
8712 // introduced loads cannot trap! Something like this is valid as long as
8713 // the condition is always false: load (select bool %C, int* null, int* %G),
8714 // but it would not be valid if we transformed it to load from null
8717 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
8718 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
8719 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
8720 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
8721 Value *V1 = Builder->CreateLoad(SI->getOperand(1),
8722 SI->getOperand(1)->getName()+".val");
8723 Value *V2 = Builder->CreateLoad(SI->getOperand(2),
8724 SI->getOperand(2)->getName()+".val");
8725 return SelectInst::Create(SI->getCondition(), V1, V2);
8728 // load (select (cond, null, P)) -> load P
8729 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
8730 if (C->isNullValue()) {
8731 LI.setOperand(0, SI->getOperand(2));
8735 // load (select (cond, P, null)) -> load P
8736 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
8737 if (C->isNullValue()) {
8738 LI.setOperand(0, SI->getOperand(1));
8746 /// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
8747 /// when possible. This makes it generally easy to do alias analysis and/or
8748 /// SROA/mem2reg of the memory object.
8749 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
8750 User *CI = cast<User>(SI.getOperand(1));
8751 Value *CastOp = CI->getOperand(0);
8753 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
8754 const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType());
8755 if (SrcTy == 0) return 0;
8757 const Type *SrcPTy = SrcTy->getElementType();
8759 if (!DestPTy->isInteger() && !isa<PointerType>(DestPTy))
8762 /// NewGEPIndices - If SrcPTy is an aggregate type, we can emit a "noop gep"
8763 /// to its first element. This allows us to handle things like:
8764 /// store i32 xxx, (bitcast {foo*, float}* %P to i32*)
8765 /// on 32-bit hosts.
8766 SmallVector<Value*, 4> NewGEPIndices;
8768 // If the source is an array, the code below will not succeed. Check to
8769 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
8771 if (isa<ArrayType>(SrcPTy) || isa<StructType>(SrcPTy)) {
8772 // Index through pointer.
8773 Constant *Zero = Constant::getNullValue(Type::getInt32Ty(SI.getContext()));
8774 NewGEPIndices.push_back(Zero);
8777 if (const StructType *STy = dyn_cast<StructType>(SrcPTy)) {
8778 if (!STy->getNumElements()) /* Struct can be empty {} */
8780 NewGEPIndices.push_back(Zero);
8781 SrcPTy = STy->getElementType(0);
8782 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcPTy)) {
8783 NewGEPIndices.push_back(Zero);
8784 SrcPTy = ATy->getElementType();
8790 SrcTy = PointerType::get(SrcPTy, SrcTy->getAddressSpace());
8793 if (!SrcPTy->isInteger() && !isa<PointerType>(SrcPTy))
8796 // If the pointers point into different address spaces or if they point to
8797 // values with different sizes, we can't do the transformation.
8798 if (!IC.getTargetData() ||
8799 SrcTy->getAddressSpace() !=
8800 cast<PointerType>(CI->getType())->getAddressSpace() ||
8801 IC.getTargetData()->getTypeSizeInBits(SrcPTy) !=
8802 IC.getTargetData()->getTypeSizeInBits(DestPTy))
8805 // Okay, we are casting from one integer or pointer type to another of
8806 // the same size. Instead of casting the pointer before
8807 // the store, cast the value to be stored.
8809 Value *SIOp0 = SI.getOperand(0);
8810 Instruction::CastOps opcode = Instruction::BitCast;
8811 const Type* CastSrcTy = SIOp0->getType();
8812 const Type* CastDstTy = SrcPTy;
8813 if (isa<PointerType>(CastDstTy)) {
8814 if (CastSrcTy->isInteger())
8815 opcode = Instruction::IntToPtr;
8816 } else if (isa<IntegerType>(CastDstTy)) {
8817 if (isa<PointerType>(SIOp0->getType()))
8818 opcode = Instruction::PtrToInt;
8821 // SIOp0 is a pointer to aggregate and this is a store to the first field,
8822 // emit a GEP to index into its first field.
8823 if (!NewGEPIndices.empty())
8824 CastOp = IC.Builder->CreateInBoundsGEP(CastOp, NewGEPIndices.begin(),
8825 NewGEPIndices.end());
8827 NewCast = IC.Builder->CreateCast(opcode, SIOp0, CastDstTy,
8828 SIOp0->getName()+".c");
8829 return new StoreInst(NewCast, CastOp);
8832 /// equivalentAddressValues - Test if A and B will obviously have the same
8833 /// value. This includes recognizing that %t0 and %t1 will have the same
8834 /// value in code like this:
8835 /// %t0 = getelementptr \@a, 0, 3
8836 /// store i32 0, i32* %t0
8837 /// %t1 = getelementptr \@a, 0, 3
8838 /// %t2 = load i32* %t1
8840 static bool equivalentAddressValues(Value *A, Value *B) {
8841 // Test if the values are trivially equivalent.
8842 if (A == B) return true;
8844 // Test if the values come form identical arithmetic instructions.
8845 // This uses isIdenticalToWhenDefined instead of isIdenticalTo because
8846 // its only used to compare two uses within the same basic block, which
8847 // means that they'll always either have the same value or one of them
8848 // will have an undefined value.
8849 if (isa<BinaryOperator>(A) ||
8852 isa<GetElementPtrInst>(A))
8853 if (Instruction *BI = dyn_cast<Instruction>(B))
8854 if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
8857 // Otherwise they may not be equivalent.
8861 // If this instruction has two uses, one of which is a llvm.dbg.declare,
8862 // return the llvm.dbg.declare.
8863 DbgDeclareInst *InstCombiner::hasOneUsePlusDeclare(Value *V) {
8864 if (!V->hasNUses(2))
8866 for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
8868 if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI))
8870 if (isa<BitCastInst>(UI) && UI->hasOneUse()) {
8871 if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI->use_begin()))
8878 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
8879 Value *Val = SI.getOperand(0);
8880 Value *Ptr = SI.getOperand(1);
8882 // If the RHS is an alloca with a single use, zapify the store, making the
8884 // If the RHS is an alloca with a two uses, the other one being a
8885 // llvm.dbg.declare, zapify the store and the declare, making the
8886 // alloca dead. We must do this to prevent declare's from affecting
8888 if (!SI.isVolatile()) {
8889 if (Ptr->hasOneUse()) {
8890 if (isa<AllocaInst>(Ptr)) {
8891 EraseInstFromFunction(SI);
8895 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
8896 if (isa<AllocaInst>(GEP->getOperand(0))) {
8897 if (GEP->getOperand(0)->hasOneUse()) {
8898 EraseInstFromFunction(SI);
8902 if (DbgDeclareInst *DI = hasOneUsePlusDeclare(GEP->getOperand(0))) {
8903 EraseInstFromFunction(*DI);
8904 EraseInstFromFunction(SI);
8911 if (DbgDeclareInst *DI = hasOneUsePlusDeclare(Ptr)) {
8912 EraseInstFromFunction(*DI);
8913 EraseInstFromFunction(SI);
8919 // Attempt to improve the alignment.
8921 unsigned KnownAlign =
8922 GetOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()));
8924 (SI.getAlignment() == 0 ? TD->getABITypeAlignment(Val->getType()) :
8926 SI.setAlignment(KnownAlign);
8929 // Do really simple DSE, to catch cases where there are several consecutive
8930 // stores to the same location, separated by a few arithmetic operations. This
8931 // situation often occurs with bitfield accesses.
8932 BasicBlock::iterator BBI = &SI;
8933 for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
8936 // Don't count debug info directives, lest they affect codegen,
8937 // and we skip pointer-to-pointer bitcasts, which are NOPs.
8938 // It is necessary for correctness to skip those that feed into a
8939 // llvm.dbg.declare, as these are not present when debugging is off.
8940 if (isa<DbgInfoIntrinsic>(BBI) ||
8941 (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
8946 if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
8947 // Prev store isn't volatile, and stores to the same location?
8948 if (!PrevSI->isVolatile() &&equivalentAddressValues(PrevSI->getOperand(1),
8949 SI.getOperand(1))) {
8952 EraseInstFromFunction(*PrevSI);
8958 // If this is a load, we have to stop. However, if the loaded value is from
8959 // the pointer we're loading and is producing the pointer we're storing,
8960 // then *this* store is dead (X = load P; store X -> P).
8961 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
8962 if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
8964 EraseInstFromFunction(SI);
8968 // Otherwise, this is a load from some other location. Stores before it
8973 // Don't skip over loads or things that can modify memory.
8974 if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory())
8979 if (SI.isVolatile()) return 0; // Don't hack volatile stores.
8981 // store X, null -> turns into 'unreachable' in SimplifyCFG
8982 if (isa<ConstantPointerNull>(Ptr) && SI.getPointerAddressSpace() == 0) {
8983 if (!isa<UndefValue>(Val)) {
8984 SI.setOperand(0, UndefValue::get(Val->getType()));
8985 if (Instruction *U = dyn_cast<Instruction>(Val))
8986 Worklist.Add(U); // Dropped a use.
8989 return 0; // Do not modify these!
8992 // store undef, Ptr -> noop
8993 if (isa<UndefValue>(Val)) {
8994 EraseInstFromFunction(SI);
8999 // If the pointer destination is a cast, see if we can fold the cast into the
9001 if (isa<CastInst>(Ptr))
9002 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
9004 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
9006 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
9010 // If this store is the last instruction in the basic block (possibly
9011 // excepting debug info instructions and the pointer bitcasts that feed
9012 // into them), and if the block ends with an unconditional branch, try
9013 // to move it to the successor block.
9017 } while (isa<DbgInfoIntrinsic>(BBI) ||
9018 (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType())));
9019 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
9020 if (BI->isUnconditional())
9021 if (SimplifyStoreAtEndOfBlock(SI))
9022 return 0; // xform done!
9027 /// SimplifyStoreAtEndOfBlock - Turn things like:
9028 /// if () { *P = v1; } else { *P = v2 }
9029 /// into a phi node with a store in the successor.
9031 /// Simplify things like:
9032 /// *P = v1; if () { *P = v2; }
9033 /// into a phi node with a store in the successor.
9035 bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
9036 BasicBlock *StoreBB = SI.getParent();
9038 // Check to see if the successor block has exactly two incoming edges. If
9039 // so, see if the other predecessor contains a store to the same location.
9040 // if so, insert a PHI node (if needed) and move the stores down.
9041 BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
9043 // Determine whether Dest has exactly two predecessors and, if so, compute
9044 // the other predecessor.
9045 pred_iterator PI = pred_begin(DestBB);
9046 BasicBlock *OtherBB = 0;
9050 if (PI == pred_end(DestBB))
9053 if (*PI != StoreBB) {
9058 if (++PI != pred_end(DestBB))
9061 // Bail out if all the relevant blocks aren't distinct (this can happen,
9062 // for example, if SI is in an infinite loop)
9063 if (StoreBB == DestBB || OtherBB == DestBB)
9066 // Verify that the other block ends in a branch and is not otherwise empty.
9067 BasicBlock::iterator BBI = OtherBB->getTerminator();
9068 BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
9069 if (!OtherBr || BBI == OtherBB->begin())
9072 // If the other block ends in an unconditional branch, check for the 'if then
9073 // else' case. there is an instruction before the branch.
9074 StoreInst *OtherStore = 0;
9075 if (OtherBr->isUnconditional()) {
9077 // Skip over debugging info.
9078 while (isa<DbgInfoIntrinsic>(BBI) ||
9079 (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
9080 if (BBI==OtherBB->begin())
9084 // If this isn't a store, isn't a store to the same location, or if the
9085 // alignments differ, bail out.
9086 OtherStore = dyn_cast<StoreInst>(BBI);
9087 if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1) ||
9088 OtherStore->getAlignment() != SI.getAlignment())
9091 // Otherwise, the other block ended with a conditional branch. If one of the
9092 // destinations is StoreBB, then we have the if/then case.
9093 if (OtherBr->getSuccessor(0) != StoreBB &&
9094 OtherBr->getSuccessor(1) != StoreBB)
9097 // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
9098 // if/then triangle. See if there is a store to the same ptr as SI that
9099 // lives in OtherBB.
9101 // Check to see if we find the matching store.
9102 if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
9103 if (OtherStore->getOperand(1) != SI.getOperand(1) ||
9104 OtherStore->getAlignment() != SI.getAlignment())
9108 // If we find something that may be using or overwriting the stored
9109 // value, or if we run out of instructions, we can't do the xform.
9110 if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() ||
9111 BBI == OtherBB->begin())
9115 // In order to eliminate the store in OtherBr, we have to
9116 // make sure nothing reads or overwrites the stored value in
9118 for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
9119 // FIXME: This should really be AA driven.
9120 if (I->mayReadFromMemory() || I->mayWriteToMemory())
9125 // Insert a PHI node now if we need it.
9126 Value *MergedVal = OtherStore->getOperand(0);
9127 if (MergedVal != SI.getOperand(0)) {
9128 PHINode *PN = PHINode::Create(MergedVal->getType(), "storemerge");
9129 PN->reserveOperandSpace(2);
9130 PN->addIncoming(SI.getOperand(0), SI.getParent());
9131 PN->addIncoming(OtherStore->getOperand(0), OtherBB);
9132 MergedVal = InsertNewInstBefore(PN, DestBB->front());
9135 // Advance to a place where it is safe to insert the new store and
9137 BBI = DestBB->getFirstNonPHI();
9138 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
9139 OtherStore->isVolatile(),
9140 SI.getAlignment()), *BBI);
9142 // Nuke the old stores.
9143 EraseInstFromFunction(SI);
9144 EraseInstFromFunction(*OtherStore);
9150 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
9151 // Change br (not X), label True, label False to: br X, label False, True
9153 BasicBlock *TrueDest;
9154 BasicBlock *FalseDest;
9155 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
9156 !isa<Constant>(X)) {
9157 // Swap Destinations and condition...
9159 BI.setSuccessor(0, FalseDest);
9160 BI.setSuccessor(1, TrueDest);
9164 // Cannonicalize fcmp_one -> fcmp_oeq
9165 FCmpInst::Predicate FPred; Value *Y;
9166 if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
9167 TrueDest, FalseDest)) &&
9168 BI.getCondition()->hasOneUse())
9169 if (FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
9170 FPred == FCmpInst::FCMP_OGE) {
9171 FCmpInst *Cond = cast<FCmpInst>(BI.getCondition());
9172 Cond->setPredicate(FCmpInst::getInversePredicate(FPred));
9174 // Swap Destinations and condition.
9175 BI.setSuccessor(0, FalseDest);
9176 BI.setSuccessor(1, TrueDest);
9181 // Cannonicalize icmp_ne -> icmp_eq
9182 ICmpInst::Predicate IPred;
9183 if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
9184 TrueDest, FalseDest)) &&
9185 BI.getCondition()->hasOneUse())
9186 if (IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
9187 IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
9188 IPred == ICmpInst::ICMP_SGE) {
9189 ICmpInst *Cond = cast<ICmpInst>(BI.getCondition());
9190 Cond->setPredicate(ICmpInst::getInversePredicate(IPred));
9191 // Swap Destinations and condition.
9192 BI.setSuccessor(0, FalseDest);
9193 BI.setSuccessor(1, TrueDest);
9201 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
9202 Value *Cond = SI.getCondition();
9203 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
9204 if (I->getOpcode() == Instruction::Add)
9205 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
9206 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
9207 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
9209 ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
9211 SI.setOperand(0, I->getOperand(0));
9219 Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
9220 Value *Agg = EV.getAggregateOperand();
9222 if (!EV.hasIndices())
9223 return ReplaceInstUsesWith(EV, Agg);
9225 if (Constant *C = dyn_cast<Constant>(Agg)) {
9226 if (isa<UndefValue>(C))
9227 return ReplaceInstUsesWith(EV, UndefValue::get(EV.getType()));
9229 if (isa<ConstantAggregateZero>(C))
9230 return ReplaceInstUsesWith(EV, Constant::getNullValue(EV.getType()));
9232 if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) {
9233 // Extract the element indexed by the first index out of the constant
9234 Value *V = C->getOperand(*EV.idx_begin());
9235 if (EV.getNumIndices() > 1)
9236 // Extract the remaining indices out of the constant indexed by the
9238 return ExtractValueInst::Create(V, EV.idx_begin() + 1, EV.idx_end());
9240 return ReplaceInstUsesWith(EV, V);
9242 return 0; // Can't handle other constants
9244 if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
9245 // We're extracting from an insertvalue instruction, compare the indices
9246 const unsigned *exti, *exte, *insi, *inse;
9247 for (exti = EV.idx_begin(), insi = IV->idx_begin(),
9248 exte = EV.idx_end(), inse = IV->idx_end();
9249 exti != exte && insi != inse;
9252 // The insert and extract both reference distinctly different elements.
9253 // This means the extract is not influenced by the insert, and we can
9254 // replace the aggregate operand of the extract with the aggregate
9255 // operand of the insert. i.e., replace
9256 // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
9257 // %E = extractvalue { i32, { i32 } } %I, 0
9259 // %E = extractvalue { i32, { i32 } } %A, 0
9260 return ExtractValueInst::Create(IV->getAggregateOperand(),
9261 EV.idx_begin(), EV.idx_end());
9263 if (exti == exte && insi == inse)
9264 // Both iterators are at the end: Index lists are identical. Replace
9265 // %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
9266 // %C = extractvalue { i32, { i32 } } %B, 1, 0
9268 return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand());
9270 // The extract list is a prefix of the insert list. i.e. replace
9271 // %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
9272 // %E = extractvalue { i32, { i32 } } %I, 1
9274 // %X = extractvalue { i32, { i32 } } %A, 1
9275 // %E = insertvalue { i32 } %X, i32 42, 0
9276 // by switching the order of the insert and extract (though the
9277 // insertvalue should be left in, since it may have other uses).
9278 Value *NewEV = Builder->CreateExtractValue(IV->getAggregateOperand(),
9279 EV.idx_begin(), EV.idx_end());
9280 return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(),
9284 // The insert list is a prefix of the extract list
9285 // We can simply remove the common indices from the extract and make it
9286 // operate on the inserted value instead of the insertvalue result.
9288 // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
9289 // %E = extractvalue { i32, { i32 } } %I, 1, 0
9291 // %E extractvalue { i32 } { i32 42 }, 0
9292 return ExtractValueInst::Create(IV->getInsertedValueOperand(),
9295 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Agg)) {
9296 // We're extracting from an intrinsic, see if we're the only user, which
9297 // allows us to simplify multiple result intrinsics to simpler things that
9298 // just get one value..
9299 if (II->hasOneUse()) {
9300 // Check if we're grabbing the overflow bit or the result of a 'with
9301 // overflow' intrinsic. If it's the latter we can remove the intrinsic
9302 // and replace it with a traditional binary instruction.
9303 switch (II->getIntrinsicID()) {
9304 case Intrinsic::uadd_with_overflow:
9305 case Intrinsic::sadd_with_overflow:
9306 if (*EV.idx_begin() == 0) { // Normal result.
9307 Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
9308 II->replaceAllUsesWith(UndefValue::get(II->getType()));
9309 EraseInstFromFunction(*II);
9310 return BinaryOperator::CreateAdd(LHS, RHS);
9313 case Intrinsic::usub_with_overflow:
9314 case Intrinsic::ssub_with_overflow:
9315 if (*EV.idx_begin() == 0) { // Normal result.
9316 Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
9317 II->replaceAllUsesWith(UndefValue::get(II->getType()));
9318 EraseInstFromFunction(*II);
9319 return BinaryOperator::CreateSub(LHS, RHS);
9322 case Intrinsic::umul_with_overflow:
9323 case Intrinsic::smul_with_overflow:
9324 if (*EV.idx_begin() == 0) { // Normal result.
9325 Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
9326 II->replaceAllUsesWith(UndefValue::get(II->getType()));
9327 EraseInstFromFunction(*II);
9328 return BinaryOperator::CreateMul(LHS, RHS);
9336 // Can't simplify extracts from other values. Note that nested extracts are
9337 // already simplified implicitely by the above (extract ( extract (insert) )
9338 // will be translated into extract ( insert ( extract ) ) first and then just
9339 // the value inserted, if appropriate).
9343 /// CheapToScalarize - Return true if the value is cheaper to scalarize than it
9344 /// is to leave as a vector operation.
9345 static bool CheapToScalarize(Value *V, bool isConstant) {
9346 if (isa<ConstantAggregateZero>(V))
9348 if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
9349 if (isConstant) return true;
9350 // If all elts are the same, we can extract.
9351 Constant *Op0 = C->getOperand(0);
9352 for (unsigned i = 1; i < C->getNumOperands(); ++i)
9353 if (C->getOperand(i) != Op0)
9357 Instruction *I = dyn_cast<Instruction>(V);
9358 if (!I) return false;
9360 // Insert element gets simplified to the inserted element or is deleted if
9361 // this is constant idx extract element and its a constant idx insertelt.
9362 if (I->getOpcode() == Instruction::InsertElement && isConstant &&
9363 isa<ConstantInt>(I->getOperand(2)))
9365 if (I->getOpcode() == Instruction::Load && I->hasOneUse())
9367 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
9368 if (BO->hasOneUse() &&
9369 (CheapToScalarize(BO->getOperand(0), isConstant) ||
9370 CheapToScalarize(BO->getOperand(1), isConstant)))
9372 if (CmpInst *CI = dyn_cast<CmpInst>(I))
9373 if (CI->hasOneUse() &&
9374 (CheapToScalarize(CI->getOperand(0), isConstant) ||
9375 CheapToScalarize(CI->getOperand(1), isConstant)))
9381 /// Read and decode a shufflevector mask.
9383 /// It turns undef elements into values that are larger than the number of
9384 /// elements in the input.
9385 static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
9386 unsigned NElts = SVI->getType()->getNumElements();
9387 if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
9388 return std::vector<unsigned>(NElts, 0);
9389 if (isa<UndefValue>(SVI->getOperand(2)))
9390 return std::vector<unsigned>(NElts, 2*NElts);
9392 std::vector<unsigned> Result;
9393 const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
9394 for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
9395 if (isa<UndefValue>(*i))
9396 Result.push_back(NElts*2); // undef -> 8
9398 Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
9402 /// FindScalarElement - Given a vector and an element number, see if the scalar
9403 /// value is already around as a register, for example if it were inserted then
9404 /// extracted from the vector.
9405 static Value *FindScalarElement(Value *V, unsigned EltNo) {
9406 assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
9407 const VectorType *PTy = cast<VectorType>(V->getType());
9408 unsigned Width = PTy->getNumElements();
9409 if (EltNo >= Width) // Out of range access.
9410 return UndefValue::get(PTy->getElementType());
9412 if (isa<UndefValue>(V))
9413 return UndefValue::get(PTy->getElementType());
9414 else if (isa<ConstantAggregateZero>(V))
9415 return Constant::getNullValue(PTy->getElementType());
9416 else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
9417 return CP->getOperand(EltNo);
9418 else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
9419 // If this is an insert to a variable element, we don't know what it is.
9420 if (!isa<ConstantInt>(III->getOperand(2)))
9422 unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
9424 // If this is an insert to the element we are looking for, return the
9427 return III->getOperand(1);
9429 // Otherwise, the insertelement doesn't modify the value, recurse on its
9431 return FindScalarElement(III->getOperand(0), EltNo);
9432 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
9434 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
9435 unsigned InEl = getShuffleMask(SVI)[EltNo];
9436 if (InEl < LHSWidth)
9437 return FindScalarElement(SVI->getOperand(0), InEl);
9438 else if (InEl < LHSWidth*2)
9439 return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
9441 return UndefValue::get(PTy->getElementType());
9444 // Otherwise, we don't know.
9448 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
9449 // If vector val is undef, replace extract with scalar undef.
9450 if (isa<UndefValue>(EI.getOperand(0)))
9451 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9453 // If vector val is constant 0, replace extract with scalar 0.
9454 if (isa<ConstantAggregateZero>(EI.getOperand(0)))
9455 return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
9457 if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
9458 // If vector val is constant with all elements the same, replace EI with
9459 // that element. When the elements are not identical, we cannot replace yet
9460 // (we do that below, but only when the index is constant).
9461 Constant *op0 = C->getOperand(0);
9462 for (unsigned i = 1; i != C->getNumOperands(); ++i)
9463 if (C->getOperand(i) != op0) {
9468 return ReplaceInstUsesWith(EI, op0);
9471 // If extracting a specified index from the vector, see if we can recursively
9472 // find a previously computed scalar that was inserted into the vector.
9473 if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
9474 unsigned IndexVal = IdxC->getZExtValue();
9475 unsigned VectorWidth = EI.getVectorOperandType()->getNumElements();
9477 // If this is extracting an invalid index, turn this into undef, to avoid
9478 // crashing the code below.
9479 if (IndexVal >= VectorWidth)
9480 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9482 // This instruction only demands the single element from the input vector.
9483 // If the input vector has a single use, simplify it based on this use
9485 if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
9486 APInt UndefElts(VectorWidth, 0);
9487 APInt DemandedMask(VectorWidth, 1 << IndexVal);
9488 if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
9489 DemandedMask, UndefElts)) {
9490 EI.setOperand(0, V);
9495 if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
9496 return ReplaceInstUsesWith(EI, Elt);
9498 // If the this extractelement is directly using a bitcast from a vector of
9499 // the same number of elements, see if we can find the source element from
9500 // it. In this case, we will end up needing to bitcast the scalars.
9501 if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
9502 if (const VectorType *VT =
9503 dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
9504 if (VT->getNumElements() == VectorWidth)
9505 if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
9506 return new BitCastInst(Elt, EI.getType());
9510 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
9511 // Push extractelement into predecessor operation if legal and
9512 // profitable to do so
9513 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
9514 if (I->hasOneUse() &&
9515 CheapToScalarize(BO, isa<ConstantInt>(EI.getOperand(1)))) {
9517 Builder->CreateExtractElement(BO->getOperand(0), EI.getOperand(1),
9518 EI.getName()+".lhs");
9520 Builder->CreateExtractElement(BO->getOperand(1), EI.getOperand(1),
9521 EI.getName()+".rhs");
9522 return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
9524 } else if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
9525 // Extracting the inserted element?
9526 if (IE->getOperand(2) == EI.getOperand(1))
9527 return ReplaceInstUsesWith(EI, IE->getOperand(1));
9528 // If the inserted and extracted elements are constants, they must not
9529 // be the same value, extract from the pre-inserted value instead.
9530 if (isa<Constant>(IE->getOperand(2)) && isa<Constant>(EI.getOperand(1))) {
9531 Worklist.AddValue(EI.getOperand(0));
9532 EI.setOperand(0, IE->getOperand(0));
9535 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
9536 // If this is extracting an element from a shufflevector, figure out where
9537 // it came from and extract from the appropriate input element instead.
9538 if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
9539 unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
9542 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
9544 if (SrcIdx < LHSWidth)
9545 Src = SVI->getOperand(0);
9546 else if (SrcIdx < LHSWidth*2) {
9548 Src = SVI->getOperand(1);
9550 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
9552 return ExtractElementInst::Create(Src,
9553 ConstantInt::get(Type::getInt32Ty(EI.getContext()),
9557 // FIXME: Canonicalize extractelement(bitcast) -> bitcast(extractelement)
9562 /// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
9563 /// elements from either LHS or RHS, return the shuffle mask and true.
9564 /// Otherwise, return false.
9565 static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
9566 std::vector<Constant*> &Mask) {
9567 assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
9568 "Invalid CollectSingleShuffleElements");
9569 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
9571 if (isa<UndefValue>(V)) {
9572 Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
9577 for (unsigned i = 0; i != NumElts; ++i)
9578 Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
9583 for (unsigned i = 0; i != NumElts; ++i)
9584 Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()),
9589 if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
9590 // If this is an insert of an extract from some other vector, include it.
9591 Value *VecOp = IEI->getOperand(0);
9592 Value *ScalarOp = IEI->getOperand(1);
9593 Value *IdxOp = IEI->getOperand(2);
9595 if (!isa<ConstantInt>(IdxOp))
9597 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
9599 if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
9600 // Okay, we can handle this if the vector we are insertinting into is
9602 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
9603 // If so, update the mask to reflect the inserted undef.
9604 Mask[InsertedIdx] = UndefValue::get(Type::getInt32Ty(V->getContext()));
9607 } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
9608 if (isa<ConstantInt>(EI->getOperand(1)) &&
9609 EI->getOperand(0)->getType() == V->getType()) {
9610 unsigned ExtractedIdx =
9611 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
9613 // This must be extracting from either LHS or RHS.
9614 if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
9615 // Okay, we can handle this if the vector we are insertinting into is
9617 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
9618 // If so, update the mask to reflect the inserted value.
9619 if (EI->getOperand(0) == LHS) {
9620 Mask[InsertedIdx % NumElts] =
9621 ConstantInt::get(Type::getInt32Ty(V->getContext()),
9624 assert(EI->getOperand(0) == RHS);
9625 Mask[InsertedIdx % NumElts] =
9626 ConstantInt::get(Type::getInt32Ty(V->getContext()),
9627 ExtractedIdx+NumElts);
9636 // TODO: Handle shufflevector here!
9641 /// CollectShuffleElements - We are building a shuffle of V, using RHS as the
9642 /// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
9643 /// that computes V and the LHS value of the shuffle.
9644 static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
9646 assert(isa<VectorType>(V->getType()) &&
9647 (RHS == 0 || V->getType() == RHS->getType()) &&
9648 "Invalid shuffle!");
9649 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
9651 if (isa<UndefValue>(V)) {
9652 Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
9654 } else if (isa<ConstantAggregateZero>(V)) {
9655 Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(V->getContext()),0));
9657 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
9658 // If this is an insert of an extract from some other vector, include it.
9659 Value *VecOp = IEI->getOperand(0);
9660 Value *ScalarOp = IEI->getOperand(1);
9661 Value *IdxOp = IEI->getOperand(2);
9663 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
9664 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
9665 EI->getOperand(0)->getType() == V->getType()) {
9666 unsigned ExtractedIdx =
9667 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
9668 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
9670 // Either the extracted from or inserted into vector must be RHSVec,
9671 // otherwise we'd end up with a shuffle of three inputs.
9672 if (EI->getOperand(0) == RHS || RHS == 0) {
9673 RHS = EI->getOperand(0);
9674 Value *V = CollectShuffleElements(VecOp, Mask, RHS);
9675 Mask[InsertedIdx % NumElts] =
9676 ConstantInt::get(Type::getInt32Ty(V->getContext()),
9677 NumElts+ExtractedIdx);
9682 Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
9683 // Everything but the extracted element is replaced with the RHS.
9684 for (unsigned i = 0; i != NumElts; ++i) {
9685 if (i != InsertedIdx)
9686 Mask[i] = ConstantInt::get(Type::getInt32Ty(V->getContext()),
9692 // If this insertelement is a chain that comes from exactly these two
9693 // vectors, return the vector and the effective shuffle.
9694 if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
9695 return EI->getOperand(0);
9699 // TODO: Handle shufflevector here!
9701 // Otherwise, can't do anything fancy. Return an identity vector.
9702 for (unsigned i = 0; i != NumElts; ++i)
9703 Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
9707 Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
9708 Value *VecOp = IE.getOperand(0);
9709 Value *ScalarOp = IE.getOperand(1);
9710 Value *IdxOp = IE.getOperand(2);
9712 // Inserting an undef or into an undefined place, remove this.
9713 if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
9714 ReplaceInstUsesWith(IE, VecOp);
9716 // If the inserted element was extracted from some other vector, and if the
9717 // indexes are constant, try to turn this into a shufflevector operation.
9718 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
9719 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
9720 EI->getOperand(0)->getType() == IE.getType()) {
9721 unsigned NumVectorElts = IE.getType()->getNumElements();
9722 unsigned ExtractedIdx =
9723 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
9724 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
9726 if (ExtractedIdx >= NumVectorElts) // Out of range extract.
9727 return ReplaceInstUsesWith(IE, VecOp);
9729 if (InsertedIdx >= NumVectorElts) // Out of range insert.
9730 return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
9732 // If we are extracting a value from a vector, then inserting it right
9733 // back into the same place, just use the input vector.
9734 if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
9735 return ReplaceInstUsesWith(IE, VecOp);
9737 // If this insertelement isn't used by some other insertelement, turn it
9738 // (and any insertelements it points to), into one big shuffle.
9739 if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
9740 std::vector<Constant*> Mask;
9742 Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
9743 if (RHS == 0) RHS = UndefValue::get(LHS->getType());
9744 // We now have a shuffle of LHS, RHS, Mask.
9745 return new ShuffleVectorInst(LHS, RHS,
9746 ConstantVector::get(Mask));
9751 unsigned VWidth = cast<VectorType>(VecOp->getType())->getNumElements();
9752 APInt UndefElts(VWidth, 0);
9753 APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
9754 if (SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts))
9761 Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
9762 Value *LHS = SVI.getOperand(0);
9763 Value *RHS = SVI.getOperand(1);
9764 std::vector<unsigned> Mask = getShuffleMask(&SVI);
9766 bool MadeChange = false;
9768 // Undefined shuffle mask -> undefined value.
9769 if (isa<UndefValue>(SVI.getOperand(2)))
9770 return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
9772 unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
9774 if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
9777 APInt UndefElts(VWidth, 0);
9778 APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
9779 if (SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
9780 LHS = SVI.getOperand(0);
9781 RHS = SVI.getOperand(1);
9785 // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
9786 // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
9787 if (LHS == RHS || isa<UndefValue>(LHS)) {
9788 if (isa<UndefValue>(LHS) && LHS == RHS) {
9789 // shuffle(undef,undef,mask) -> undef.
9790 return ReplaceInstUsesWith(SVI, LHS);
9793 // Remap any references to RHS to use LHS.
9794 std::vector<Constant*> Elts;
9795 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
9797 Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
9799 if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
9800 (Mask[i] < e && isa<UndefValue>(LHS))) {
9801 Mask[i] = 2*e; // Turn into undef.
9802 Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
9804 Mask[i] = Mask[i] % e; // Force to LHS.
9805 Elts.push_back(ConstantInt::get(Type::getInt32Ty(SVI.getContext()),
9810 SVI.setOperand(0, SVI.getOperand(1));
9811 SVI.setOperand(1, UndefValue::get(RHS->getType()));
9812 SVI.setOperand(2, ConstantVector::get(Elts));
9813 LHS = SVI.getOperand(0);
9814 RHS = SVI.getOperand(1);
9818 // Analyze the shuffle, are the LHS or RHS and identity shuffles?
9819 bool isLHSID = true, isRHSID = true;
9821 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
9822 if (Mask[i] >= e*2) continue; // Ignore undef values.
9823 // Is this an identity shuffle of the LHS value?
9824 isLHSID &= (Mask[i] == i);
9826 // Is this an identity shuffle of the RHS value?
9827 isRHSID &= (Mask[i]-e == i);
9830 // Eliminate identity shuffles.
9831 if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
9832 if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
9834 // If the LHS is a shufflevector itself, see if we can combine it with this
9835 // one without producing an unusual shuffle. Here we are really conservative:
9836 // we are absolutely afraid of producing a shuffle mask not in the input
9837 // program, because the code gen may not be smart enough to turn a merged
9838 // shuffle into two specific shuffles: it may produce worse code. As such,
9839 // we only merge two shuffles if the result is one of the two input shuffle
9840 // masks. In this case, merging the shuffles just removes one instruction,
9841 // which we know is safe. This is good for things like turning:
9842 // (splat(splat)) -> splat.
9843 if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
9844 if (isa<UndefValue>(RHS)) {
9845 std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
9847 if (LHSMask.size() == Mask.size()) {
9848 std::vector<unsigned> NewMask;
9849 for (unsigned i = 0, e = Mask.size(); i != e; ++i)
9851 NewMask.push_back(2*e);
9853 NewMask.push_back(LHSMask[Mask[i]]);
9855 // If the result mask is equal to the src shuffle or this
9856 // shuffle mask, do the replacement.
9857 if (NewMask == LHSMask || NewMask == Mask) {
9858 unsigned LHSInNElts =
9859 cast<VectorType>(LHSSVI->getOperand(0)->getType())->
9861 std::vector<Constant*> Elts;
9862 for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
9863 if (NewMask[i] >= LHSInNElts*2) {
9864 Elts.push_back(UndefValue::get(
9865 Type::getInt32Ty(SVI.getContext())));
9867 Elts.push_back(ConstantInt::get(
9868 Type::getInt32Ty(SVI.getContext()),
9872 return new ShuffleVectorInst(LHSSVI->getOperand(0),
9873 LHSSVI->getOperand(1),
9874 ConstantVector::get(Elts));
9880 return MadeChange ? &SVI : 0;
9886 /// TryToSinkInstruction - Try to move the specified instruction from its
9887 /// current block into the beginning of DestBlock, which can only happen if it's
9888 /// safe to move the instruction past all of the instructions between it and the
9889 /// end of its block.
9890 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
9891 assert(I->hasOneUse() && "Invariants didn't hold!");
9893 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
9894 if (isa<PHINode>(I) || I->mayHaveSideEffects() || isa<TerminatorInst>(I))
9897 // Do not sink alloca instructions out of the entry block.
9898 if (isa<AllocaInst>(I) && I->getParent() ==
9899 &DestBlock->getParent()->getEntryBlock())
9902 // We can only sink load instructions if there is nothing between the load and
9903 // the end of block that could change the value.
9904 if (I->mayReadFromMemory()) {
9905 for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
9907 if (Scan->mayWriteToMemory())
9911 BasicBlock::iterator InsertPos = DestBlock->getFirstNonPHI();
9913 CopyPrecedingStopPoint(I, InsertPos);
9914 I->moveBefore(InsertPos);
9920 /// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
9921 /// all reachable code to the worklist.
9923 /// This has a couple of tricks to make the code faster and more powerful. In
9924 /// particular, we constant fold and DCE instructions as we go, to avoid adding
9925 /// them to the worklist (this significantly speeds up instcombine on code where
9926 /// many instructions are dead or constant). Additionally, if we find a branch
9927 /// whose condition is a known constant, we only visit the reachable successors.
9929 static bool AddReachableCodeToWorklist(BasicBlock *BB,
9930 SmallPtrSet<BasicBlock*, 64> &Visited,
9932 const TargetData *TD) {
9933 bool MadeIRChange = false;
9934 SmallVector<BasicBlock*, 256> Worklist;
9935 Worklist.push_back(BB);
9937 std::vector<Instruction*> InstrsForInstCombineWorklist;
9938 InstrsForInstCombineWorklist.reserve(128);
9940 SmallPtrSet<ConstantExpr*, 64> FoldedConstants;
9942 while (!Worklist.empty()) {
9943 BB = Worklist.back();
9944 Worklist.pop_back();
9946 // We have now visited this block! If we've already been here, ignore it.
9947 if (!Visited.insert(BB)) continue;
9949 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
9950 Instruction *Inst = BBI++;
9952 // DCE instruction if trivially dead.
9953 if (isInstructionTriviallyDead(Inst)) {
9955 DEBUG(errs() << "IC: DCE: " << *Inst << '\n');
9956 Inst->eraseFromParent();
9960 // ConstantProp instruction if trivially constant.
9961 if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
9962 if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
9963 DEBUG(errs() << "IC: ConstFold to: " << *C << " from: "
9965 Inst->replaceAllUsesWith(C);
9967 Inst->eraseFromParent();
9974 // See if we can constant fold its operands.
9975 for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end();
9977 ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
9978 if (CE == 0) continue;
9980 // If we already folded this constant, don't try again.
9981 if (!FoldedConstants.insert(CE))
9984 Constant *NewC = ConstantFoldConstantExpression(CE, TD);
9985 if (NewC && NewC != CE) {
9987 MadeIRChange = true;
9993 InstrsForInstCombineWorklist.push_back(Inst);
9996 // Recursively visit successors. If this is a branch or switch on a
9997 // constant, only visit the reachable successor.
9998 TerminatorInst *TI = BB->getTerminator();
9999 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
10000 if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
10001 bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
10002 BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
10003 Worklist.push_back(ReachableBB);
10006 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
10007 if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
10008 // See if this is an explicit destination.
10009 for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
10010 if (SI->getCaseValue(i) == Cond) {
10011 BasicBlock *ReachableBB = SI->getSuccessor(i);
10012 Worklist.push_back(ReachableBB);
10016 // Otherwise it is the default destination.
10017 Worklist.push_back(SI->getSuccessor(0));
10022 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
10023 Worklist.push_back(TI->getSuccessor(i));
10026 // Once we've found all of the instructions to add to instcombine's worklist,
10027 // add them in reverse order. This way instcombine will visit from the top
10028 // of the function down. This jives well with the way that it adds all uses
10029 // of instructions to the worklist after doing a transformation, thus avoiding
10030 // some N^2 behavior in pathological cases.
10031 IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
10032 InstrsForInstCombineWorklist.size());
10034 return MadeIRChange;
10037 bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
10038 MadeIRChange = false;
10040 DEBUG(errs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
10041 << F.getNameStr() << "\n");
10044 // Do a depth-first traversal of the function, populate the worklist with
10045 // the reachable instructions. Ignore blocks that are not reachable. Keep
10046 // track of which blocks we visit.
10047 SmallPtrSet<BasicBlock*, 64> Visited;
10048 MadeIRChange |= AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
10050 // Do a quick scan over the function. If we find any blocks that are
10051 // unreachable, remove any instructions inside of them. This prevents
10052 // the instcombine code from having to deal with some bad special cases.
10053 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
10054 if (!Visited.count(BB)) {
10055 Instruction *Term = BB->getTerminator();
10056 while (Term != BB->begin()) { // Remove instrs bottom-up
10057 BasicBlock::iterator I = Term; --I;
10059 DEBUG(errs() << "IC: DCE: " << *I << '\n');
10060 // A debug intrinsic shouldn't force another iteration if we weren't
10061 // going to do one without it.
10062 if (!isa<DbgInfoIntrinsic>(I)) {
10064 MadeIRChange = true;
10067 // If I is not void type then replaceAllUsesWith undef.
10068 // This allows ValueHandlers and custom metadata to adjust itself.
10069 if (!I->getType()->isVoidTy())
10070 I->replaceAllUsesWith(UndefValue::get(I->getType()));
10071 I->eraseFromParent();
10076 while (!Worklist.isEmpty()) {
10077 Instruction *I = Worklist.RemoveOne();
10078 if (I == 0) continue; // skip null values.
10080 // Check to see if we can DCE the instruction.
10081 if (isInstructionTriviallyDead(I)) {
10082 DEBUG(errs() << "IC: DCE: " << *I << '\n');
10083 EraseInstFromFunction(*I);
10085 MadeIRChange = true;
10089 // Instruction isn't dead, see if we can constant propagate it.
10090 if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
10091 if (Constant *C = ConstantFoldInstruction(I, TD)) {
10092 DEBUG(errs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
10094 // Add operands to the worklist.
10095 ReplaceInstUsesWith(*I, C);
10097 EraseInstFromFunction(*I);
10098 MadeIRChange = true;
10102 // See if we can trivially sink this instruction to a successor basic block.
10103 if (I->hasOneUse()) {
10104 BasicBlock *BB = I->getParent();
10105 Instruction *UserInst = cast<Instruction>(I->use_back());
10106 BasicBlock *UserParent;
10108 // Get the block the use occurs in.
10109 if (PHINode *PN = dyn_cast<PHINode>(UserInst))
10110 UserParent = PN->getIncomingBlock(I->use_begin().getUse());
10112 UserParent = UserInst->getParent();
10114 if (UserParent != BB) {
10115 bool UserIsSuccessor = false;
10116 // See if the user is one of our successors.
10117 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
10118 if (*SI == UserParent) {
10119 UserIsSuccessor = true;
10123 // If the user is one of our immediate successors, and if that successor
10124 // only has us as a predecessors (we'd have to split the critical edge
10125 // otherwise), we can keep going.
10126 if (UserIsSuccessor && UserParent->getSinglePredecessor())
10127 // Okay, the CFG is simple enough, try to sink this instruction.
10128 MadeIRChange |= TryToSinkInstruction(I, UserParent);
10132 // Now that we have an instruction, try combining it to simplify it.
10133 Builder->SetInsertPoint(I->getParent(), I);
10138 DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
10139 DEBUG(errs() << "IC: Visiting: " << OrigI << '\n');
10141 if (Instruction *Result = visit(*I)) {
10143 // Should we replace the old instruction with a new one?
10145 DEBUG(errs() << "IC: Old = " << *I << '\n'
10146 << " New = " << *Result << '\n');
10148 // Everything uses the new instruction now.
10149 I->replaceAllUsesWith(Result);
10151 // Push the new instruction and any users onto the worklist.
10152 Worklist.Add(Result);
10153 Worklist.AddUsersToWorkList(*Result);
10155 // Move the name to the new instruction first.
10156 Result->takeName(I);
10158 // Insert the new instruction into the basic block...
10159 BasicBlock *InstParent = I->getParent();
10160 BasicBlock::iterator InsertPos = I;
10162 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
10163 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
10166 InstParent->getInstList().insert(InsertPos, Result);
10168 EraseInstFromFunction(*I);
10171 DEBUG(errs() << "IC: Mod = " << OrigI << '\n'
10172 << " New = " << *I << '\n');
10175 // If the instruction was modified, it's possible that it is now dead.
10176 // if so, remove it.
10177 if (isInstructionTriviallyDead(I)) {
10178 EraseInstFromFunction(*I);
10181 Worklist.AddUsersToWorkList(*I);
10184 MadeIRChange = true;
10189 return MadeIRChange;
10193 bool InstCombiner::runOnFunction(Function &F) {
10194 MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
10195 TD = getAnalysisIfAvailable<TargetData>();
10198 /// Builder - This is an IRBuilder that automatically inserts new
10199 /// instructions into the worklist when they are created.
10200 IRBuilder<true, TargetFolder, InstCombineIRInserter>
10201 TheBuilder(F.getContext(), TargetFolder(TD),
10202 InstCombineIRInserter(Worklist));
10203 Builder = &TheBuilder;
10205 bool EverMadeChange = false;
10207 // Iterate while there is work to do.
10208 unsigned Iteration = 0;
10209 while (DoOneIteration(F, Iteration++))
10210 EverMadeChange = true;
10213 return EverMadeChange;
10216 FunctionPass *llvm::createInstructionCombiningPass() {
10217 return new InstCombiner();