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 #include "llvm/Transforms/Scalar.h"
37 #include "InstCombine.h"
38 #include "llvm-c/Initialization.h"
39 #include "llvm/ADT/SmallPtrSet.h"
40 #include "llvm/ADT/Statistic.h"
41 #include "llvm/ADT/StringSwitch.h"
42 #include "llvm/Analysis/ConstantFolding.h"
43 #include "llvm/Analysis/InstructionSimplify.h"
44 #include "llvm/Analysis/MemoryBuiltins.h"
45 #include "llvm/Analysis/ValueTracking.h"
46 #include "llvm/IR/CFG.h"
47 #include "llvm/IR/DataLayout.h"
48 #include "llvm/IR/GetElementPtrTypeIterator.h"
49 #include "llvm/IR/IntrinsicInst.h"
50 #include "llvm/IR/PatternMatch.h"
51 #include "llvm/IR/ValueHandle.h"
52 #include "llvm/Support/CommandLine.h"
53 #include "llvm/Support/Debug.h"
54 #include "llvm/Target/TargetLibraryInfo.h"
55 #include "llvm/Transforms/Utils/Local.h"
59 using namespace llvm::PatternMatch;
61 #define DEBUG_TYPE "instcombine"
63 STATISTIC(NumCombined , "Number of insts combined");
64 STATISTIC(NumConstProp, "Number of constant folds");
65 STATISTIC(NumDeadInst , "Number of dead inst eliminated");
66 STATISTIC(NumSunkInst , "Number of instructions sunk");
67 STATISTIC(NumExpand, "Number of expansions");
68 STATISTIC(NumFactor , "Number of factorizations");
69 STATISTIC(NumReassoc , "Number of reassociations");
71 static cl::opt<bool> UnsafeFPShrink("enable-double-float-shrink", cl::Hidden,
73 cl::desc("Enable unsafe double to float "
74 "shrinking for math lib calls"));
76 // Initialization Routines
77 void llvm::initializeInstCombine(PassRegistry &Registry) {
78 initializeInstCombinerPass(Registry);
81 void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
82 initializeInstCombine(*unwrap(R));
85 char InstCombiner::ID = 0;
86 INITIALIZE_PASS_BEGIN(InstCombiner, "instcombine",
87 "Combine redundant instructions", false, false)
88 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
89 INITIALIZE_PASS_END(InstCombiner, "instcombine",
90 "Combine redundant instructions", false, false)
92 void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
94 AU.addRequired<TargetLibraryInfo>();
98 Value *InstCombiner::EmitGEPOffset(User *GEP) {
99 return llvm::EmitGEPOffset(Builder, *getDataLayout(), GEP);
102 /// ShouldChangeType - Return true if it is desirable to convert a computation
103 /// from 'From' to 'To'. We don't want to convert from a legal to an illegal
104 /// type for example, or from a smaller to a larger illegal type.
105 bool InstCombiner::ShouldChangeType(Type *From, Type *To) const {
106 assert(From->isIntegerTy() && To->isIntegerTy());
108 // If we don't have DL, we don't know if the source/dest are legal.
109 if (!DL) return false;
111 unsigned FromWidth = From->getPrimitiveSizeInBits();
112 unsigned ToWidth = To->getPrimitiveSizeInBits();
113 bool FromLegal = DL->isLegalInteger(FromWidth);
114 bool ToLegal = DL->isLegalInteger(ToWidth);
116 // If this is a legal integer from type, and the result would be an illegal
117 // type, don't do the transformation.
118 if (FromLegal && !ToLegal)
121 // Otherwise, if both are illegal, do not increase the size of the result. We
122 // do allow things like i160 -> i64, but not i64 -> i160.
123 if (!FromLegal && !ToLegal && ToWidth > FromWidth)
129 // Return true, if No Signed Wrap should be maintained for I.
130 // The No Signed Wrap flag can be kept if the operation "B (I.getOpcode) C",
131 // where both B and C should be ConstantInts, results in a constant that does
132 // not overflow. This function only handles the Add and Sub opcodes. For
133 // all other opcodes, the function conservatively returns false.
134 static bool MaintainNoSignedWrap(BinaryOperator &I, Value *B, Value *C) {
135 OverflowingBinaryOperator *OBO = dyn_cast<OverflowingBinaryOperator>(&I);
136 if (!OBO || !OBO->hasNoSignedWrap()) {
140 // We reason about Add and Sub Only.
141 Instruction::BinaryOps Opcode = I.getOpcode();
142 if (Opcode != Instruction::Add &&
143 Opcode != Instruction::Sub) {
147 ConstantInt *CB = dyn_cast<ConstantInt>(B);
148 ConstantInt *CC = dyn_cast<ConstantInt>(C);
154 const APInt &BVal = CB->getValue();
155 const APInt &CVal = CC->getValue();
156 bool Overflow = false;
158 if (Opcode == Instruction::Add) {
159 BVal.sadd_ov(CVal, Overflow);
161 BVal.ssub_ov(CVal, Overflow);
167 /// Conservatively clears subclassOptionalData after a reassociation or
168 /// commutation. We preserve fast-math flags when applicable as they can be
170 static void ClearSubclassDataAfterReassociation(BinaryOperator &I) {
171 FPMathOperator *FPMO = dyn_cast<FPMathOperator>(&I);
173 I.clearSubclassOptionalData();
177 FastMathFlags FMF = I.getFastMathFlags();
178 I.clearSubclassOptionalData();
179 I.setFastMathFlags(FMF);
182 /// SimplifyAssociativeOrCommutative - This performs a few simplifications for
183 /// operators which are associative or commutative:
185 // Commutative operators:
187 // 1. Order operands such that they are listed from right (least complex) to
188 // left (most complex). This puts constants before unary operators before
191 // Associative operators:
193 // 2. Transform: "(A op B) op C" ==> "A op (B op C)" if "B op C" simplifies.
194 // 3. Transform: "A op (B op C)" ==> "(A op B) op C" if "A op B" simplifies.
196 // Associative and commutative operators:
198 // 4. Transform: "(A op B) op C" ==> "(C op A) op B" if "C op A" simplifies.
199 // 5. Transform: "A op (B op C)" ==> "B op (C op A)" if "C op A" simplifies.
200 // 6. Transform: "(A op C1) op (B op C2)" ==> "(A op B) op (C1 op C2)"
201 // if C1 and C2 are constants.
203 bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
204 Instruction::BinaryOps Opcode = I.getOpcode();
205 bool Changed = false;
208 // Order operands such that they are listed from right (least complex) to
209 // left (most complex). This puts constants before unary operators before
211 if (I.isCommutative() && getComplexity(I.getOperand(0)) <
212 getComplexity(I.getOperand(1)))
213 Changed = !I.swapOperands();
215 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(I.getOperand(0));
216 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(I.getOperand(1));
218 if (I.isAssociative()) {
219 // Transform: "(A op B) op C" ==> "A op (B op C)" if "B op C" simplifies.
220 if (Op0 && Op0->getOpcode() == Opcode) {
221 Value *A = Op0->getOperand(0);
222 Value *B = Op0->getOperand(1);
223 Value *C = I.getOperand(1);
225 // Does "B op C" simplify?
226 if (Value *V = SimplifyBinOp(Opcode, B, C, DL)) {
227 // It simplifies to V. Form "A op V".
230 // Conservatively clear the optional flags, since they may not be
231 // preserved by the reassociation.
232 if (MaintainNoSignedWrap(I, B, C) &&
233 (!Op0 || (isa<BinaryOperator>(Op0) && Op0->hasNoSignedWrap()))) {
234 // Note: this is only valid because SimplifyBinOp doesn't look at
235 // the operands to Op0.
236 I.clearSubclassOptionalData();
237 I.setHasNoSignedWrap(true);
239 ClearSubclassDataAfterReassociation(I);
248 // Transform: "A op (B op C)" ==> "(A op B) op C" if "A op B" simplifies.
249 if (Op1 && Op1->getOpcode() == Opcode) {
250 Value *A = I.getOperand(0);
251 Value *B = Op1->getOperand(0);
252 Value *C = Op1->getOperand(1);
254 // Does "A op B" simplify?
255 if (Value *V = SimplifyBinOp(Opcode, A, B, DL)) {
256 // It simplifies to V. Form "V op C".
259 // Conservatively clear the optional flags, since they may not be
260 // preserved by the reassociation.
261 ClearSubclassDataAfterReassociation(I);
269 if (I.isAssociative() && I.isCommutative()) {
270 // Transform: "(A op B) op C" ==> "(C op A) op B" if "C op A" simplifies.
271 if (Op0 && Op0->getOpcode() == Opcode) {
272 Value *A = Op0->getOperand(0);
273 Value *B = Op0->getOperand(1);
274 Value *C = I.getOperand(1);
276 // Does "C op A" simplify?
277 if (Value *V = SimplifyBinOp(Opcode, C, A, DL)) {
278 // It simplifies to V. Form "V op B".
281 // Conservatively clear the optional flags, since they may not be
282 // preserved by the reassociation.
283 ClearSubclassDataAfterReassociation(I);
290 // Transform: "A op (B op C)" ==> "B op (C op A)" if "C op A" simplifies.
291 if (Op1 && Op1->getOpcode() == Opcode) {
292 Value *A = I.getOperand(0);
293 Value *B = Op1->getOperand(0);
294 Value *C = Op1->getOperand(1);
296 // Does "C op A" simplify?
297 if (Value *V = SimplifyBinOp(Opcode, C, A, DL)) {
298 // It simplifies to V. Form "B op V".
301 // Conservatively clear the optional flags, since they may not be
302 // preserved by the reassociation.
303 ClearSubclassDataAfterReassociation(I);
310 // Transform: "(A op C1) op (B op C2)" ==> "(A op B) op (C1 op C2)"
311 // if C1 and C2 are constants.
313 Op0->getOpcode() == Opcode && Op1->getOpcode() == Opcode &&
314 isa<Constant>(Op0->getOperand(1)) &&
315 isa<Constant>(Op1->getOperand(1)) &&
316 Op0->hasOneUse() && Op1->hasOneUse()) {
317 Value *A = Op0->getOperand(0);
318 Constant *C1 = cast<Constant>(Op0->getOperand(1));
319 Value *B = Op1->getOperand(0);
320 Constant *C2 = cast<Constant>(Op1->getOperand(1));
322 Constant *Folded = ConstantExpr::get(Opcode, C1, C2);
323 BinaryOperator *New = BinaryOperator::Create(Opcode, A, B);
324 if (isa<FPMathOperator>(New)) {
325 FastMathFlags Flags = I.getFastMathFlags();
326 Flags &= Op0->getFastMathFlags();
327 Flags &= Op1->getFastMathFlags();
328 New->setFastMathFlags(Flags);
330 InsertNewInstWith(New, I);
332 I.setOperand(0, New);
333 I.setOperand(1, Folded);
334 // Conservatively clear the optional flags, since they may not be
335 // preserved by the reassociation.
336 ClearSubclassDataAfterReassociation(I);
343 // No further simplifications.
348 /// LeftDistributesOverRight - Whether "X LOp (Y ROp Z)" is always equal to
349 /// "(X LOp Y) ROp (X LOp Z)".
350 static bool LeftDistributesOverRight(Instruction::BinaryOps LOp,
351 Instruction::BinaryOps ROp) {
356 case Instruction::And:
357 // And distributes over Or and Xor.
361 case Instruction::Or:
362 case Instruction::Xor:
366 case Instruction::Mul:
367 // Multiplication distributes over addition and subtraction.
371 case Instruction::Add:
372 case Instruction::Sub:
376 case Instruction::Or:
377 // Or distributes over And.
381 case Instruction::And:
387 /// RightDistributesOverLeft - Whether "(X LOp Y) ROp Z" is always equal to
388 /// "(X ROp Z) LOp (Y ROp Z)".
389 static bool RightDistributesOverLeft(Instruction::BinaryOps LOp,
390 Instruction::BinaryOps ROp) {
391 if (Instruction::isCommutative(ROp))
392 return LeftDistributesOverRight(ROp, LOp);
393 // TODO: It would be nice to handle division, aka "(X + Y)/Z = X/Z + Y/Z",
394 // but this requires knowing that the addition does not overflow and other
399 /// This function returns identity value for given opcode, which can be used to
400 /// factor patterns like (X * 2) + X ==> (X * 2) + (X * 1) ==> X * (2 + 1).
401 static Value *getIdentityValue(Instruction::BinaryOps OpCode, Value *V) {
402 if (isa<Constant>(V))
405 if (OpCode == Instruction::Mul)
406 return ConstantInt::get(V->getType(), 1);
408 // TODO: We can handle other cases e.g. Instruction::And, Instruction::Or etc.
413 /// This function factors binary ops which can be combined using distributive
414 /// laws. This also factor SHL as MUL e.g. SHL(X, 2) ==> MUL(X, 4).
415 static Instruction::BinaryOps
416 getBinOpsForFactorization(BinaryOperator *Op, Value *&LHS, Value *&RHS) {
418 return Instruction::BinaryOpsEnd;
420 if (Op->getOpcode() == Instruction::Shl) {
421 if (Constant *CST = dyn_cast<Constant>(Op->getOperand(1))) {
422 // The multiplier is really 1 << CST.
423 RHS = ConstantExpr::getShl(ConstantInt::get(Op->getType(), 1), CST);
424 LHS = Op->getOperand(0);
425 return Instruction::Mul;
429 // TODO: We can add other conversions e.g. shr => div etc.
431 LHS = Op->getOperand(0);
432 RHS = Op->getOperand(1);
433 return Op->getOpcode();
436 /// This tries to simplify binary operations by factorizing out common terms
437 /// (e. g. "(A*B)+(A*C)" -> "A*(B+C)").
438 static Value *tryFactorization(InstCombiner::BuilderTy *Builder,
439 const DataLayout *DL, BinaryOperator &I,
440 Instruction::BinaryOps InnerOpcode, Value *A,
441 Value *B, Value *C, Value *D) {
443 // If any of A, B, C, D are null, we can not factor I, return early.
444 // Checking A and C should be enough.
445 if (!A || !C || !B || !D)
448 Value *SimplifiedInst = nullptr;
449 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
450 Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
452 // Does "X op' Y" always equal "Y op' X"?
453 bool InnerCommutative = Instruction::isCommutative(InnerOpcode);
455 // Does "X op' (Y op Z)" always equal "(X op' Y) op (X op' Z)"?
456 if (LeftDistributesOverRight(InnerOpcode, TopLevelOpcode))
457 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
458 // commutative case, "(A op' B) op (C op' A)"?
459 if (A == C || (InnerCommutative && A == D)) {
462 // Consider forming "A op' (B op D)".
463 // If "B op D" simplifies then it can be formed with no cost.
464 Value *V = SimplifyBinOp(TopLevelOpcode, B, D, DL);
465 // If "B op D" doesn't simplify then only go on if both of the existing
466 // operations "A op' B" and "C op' D" will be zapped as no longer used.
467 if (!V && LHS->hasOneUse() && RHS->hasOneUse())
468 V = Builder->CreateBinOp(TopLevelOpcode, B, D, RHS->getName());
470 SimplifiedInst = Builder->CreateBinOp(InnerOpcode, A, V);
474 // Does "(X op Y) op' Z" always equal "(X op' Z) op (Y op' Z)"?
475 if (!SimplifiedInst && RightDistributesOverLeft(TopLevelOpcode, InnerOpcode))
476 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
477 // commutative case, "(A op' B) op (B op' D)"?
478 if (B == D || (InnerCommutative && B == C)) {
481 // Consider forming "(A op C) op' B".
482 // If "A op C" simplifies then it can be formed with no cost.
483 Value *V = SimplifyBinOp(TopLevelOpcode, A, C, DL);
485 // If "A op C" doesn't simplify then only go on if both of the existing
486 // operations "A op' B" and "C op' D" will be zapped as no longer used.
487 if (!V && LHS->hasOneUse() && RHS->hasOneUse())
488 V = Builder->CreateBinOp(TopLevelOpcode, A, C, LHS->getName());
490 SimplifiedInst = Builder->CreateBinOp(InnerOpcode, V, B);
494 if (SimplifiedInst) {
496 SimplifiedInst->takeName(&I);
498 // Check if we can add NSW flag to SimplifiedInst. If so, set NSW flag.
499 // TODO: Check for NUW.
500 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(SimplifiedInst)) {
501 if (isa<OverflowingBinaryOperator>(SimplifiedInst)) {
503 if (isa<OverflowingBinaryOperator>(&I))
504 HasNSW = I.hasNoSignedWrap();
506 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
507 if (isa<OverflowingBinaryOperator>(Op0))
508 HasNSW &= Op0->hasNoSignedWrap();
510 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
511 if (isa<OverflowingBinaryOperator>(Op1))
512 HasNSW &= Op1->hasNoSignedWrap();
513 BO->setHasNoSignedWrap(HasNSW);
517 return SimplifiedInst;
520 /// SimplifyUsingDistributiveLaws - This tries to simplify binary operations
521 /// which some other binary operation distributes over either by factorizing
522 /// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this
523 /// results in simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is
524 /// a win). Returns the simplified value, or null if it didn't simplify.
525 Value *InstCombiner::SimplifyUsingDistributiveLaws(BinaryOperator &I) {
526 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
527 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
528 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
531 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
532 Instruction::BinaryOps LHSOpcode = getBinOpsForFactorization(Op0, A, B);
533 Instruction::BinaryOps RHSOpcode = getBinOpsForFactorization(Op1, C, D);
535 // The instruction has the form "(A op' B) op (C op' D)". Try to factorize
537 if (LHSOpcode == RHSOpcode) {
538 if (Value *V = tryFactorization(Builder, DL, I, LHSOpcode, A, B, C, D))
542 // The instruction has the form "(A op' B) op (C)". Try to factorize common
544 if (Value *V = tryFactorization(Builder, DL, I, LHSOpcode, A, B, RHS,
545 getIdentityValue(LHSOpcode, RHS)))
548 // The instruction has the form "(B) op (C op' D)". Try to factorize common
550 if (Value *V = tryFactorization(Builder, DL, I, RHSOpcode, LHS,
551 getIdentityValue(RHSOpcode, LHS), C, D))
555 Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
556 if (Op0 && RightDistributesOverLeft(Op0->getOpcode(), TopLevelOpcode)) {
557 // The instruction has the form "(A op' B) op C". See if expanding it out
558 // to "(A op C) op' (B op C)" results in simplifications.
559 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
560 Instruction::BinaryOps InnerOpcode = Op0->getOpcode(); // op'
562 // Do "A op C" and "B op C" both simplify?
563 if (Value *L = SimplifyBinOp(TopLevelOpcode, A, C, DL))
564 if (Value *R = SimplifyBinOp(TopLevelOpcode, B, C, DL)) {
565 // They do! Return "L op' R".
567 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
568 if ((L == A && R == B) ||
569 (Instruction::isCommutative(InnerOpcode) && L == B && R == A))
571 // Otherwise return "L op' R" if it simplifies.
572 if (Value *V = SimplifyBinOp(InnerOpcode, L, R, DL))
574 // Otherwise, create a new instruction.
575 C = Builder->CreateBinOp(InnerOpcode, L, R);
581 if (Op1 && LeftDistributesOverRight(TopLevelOpcode, Op1->getOpcode())) {
582 // The instruction has the form "A op (B op' C)". See if expanding it out
583 // to "(A op B) op' (A op C)" results in simplifications.
584 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
585 Instruction::BinaryOps InnerOpcode = Op1->getOpcode(); // op'
587 // Do "A op B" and "A op C" both simplify?
588 if (Value *L = SimplifyBinOp(TopLevelOpcode, A, B, DL))
589 if (Value *R = SimplifyBinOp(TopLevelOpcode, A, C, DL)) {
590 // They do! Return "L op' R".
592 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
593 if ((L == B && R == C) ||
594 (Instruction::isCommutative(InnerOpcode) && L == C && R == B))
596 // Otherwise return "L op' R" if it simplifies.
597 if (Value *V = SimplifyBinOp(InnerOpcode, L, R, DL))
599 // Otherwise, create a new instruction.
600 A = Builder->CreateBinOp(InnerOpcode, L, R);
609 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
610 // if the LHS is a constant zero (which is the 'negate' form).
612 Value *InstCombiner::dyn_castNegVal(Value *V) const {
613 if (BinaryOperator::isNeg(V))
614 return BinaryOperator::getNegArgument(V);
616 // Constants can be considered to be negated values if they can be folded.
617 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
618 return ConstantExpr::getNeg(C);
620 if (ConstantDataVector *C = dyn_cast<ConstantDataVector>(V))
621 if (C->getType()->getElementType()->isIntegerTy())
622 return ConstantExpr::getNeg(C);
627 // dyn_castFNegVal - Given a 'fsub' instruction, return the RHS of the
628 // instruction if the LHS is a constant negative zero (which is the 'negate'
631 Value *InstCombiner::dyn_castFNegVal(Value *V, bool IgnoreZeroSign) const {
632 if (BinaryOperator::isFNeg(V, IgnoreZeroSign))
633 return BinaryOperator::getFNegArgument(V);
635 // Constants can be considered to be negated values if they can be folded.
636 if (ConstantFP *C = dyn_cast<ConstantFP>(V))
637 return ConstantExpr::getFNeg(C);
639 if (ConstantDataVector *C = dyn_cast<ConstantDataVector>(V))
640 if (C->getType()->getElementType()->isFloatingPointTy())
641 return ConstantExpr::getFNeg(C);
646 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
648 if (CastInst *CI = dyn_cast<CastInst>(&I)) {
649 return IC->Builder->CreateCast(CI->getOpcode(), SO, I.getType());
652 // Figure out if the constant is the left or the right argument.
653 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
654 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
656 if (Constant *SOC = dyn_cast<Constant>(SO)) {
658 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
659 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
662 Value *Op0 = SO, *Op1 = ConstOperand;
666 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I)) {
667 Value *RI = IC->Builder->CreateBinOp(BO->getOpcode(), Op0, Op1,
668 SO->getName()+".op");
669 Instruction *FPInst = dyn_cast<Instruction>(RI);
670 if (FPInst && isa<FPMathOperator>(FPInst))
671 FPInst->copyFastMathFlags(BO);
674 if (ICmpInst *CI = dyn_cast<ICmpInst>(&I))
675 return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
676 SO->getName()+".cmp");
677 if (FCmpInst *CI = dyn_cast<FCmpInst>(&I))
678 return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
679 SO->getName()+".cmp");
680 llvm_unreachable("Unknown binary instruction type!");
683 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
684 // constant as the other operand, try to fold the binary operator into the
685 // select arguments. This also works for Cast instructions, which obviously do
686 // not have a second operand.
687 Instruction *InstCombiner::FoldOpIntoSelect(Instruction &Op, SelectInst *SI) {
688 // Don't modify shared select instructions
689 if (!SI->hasOneUse()) return nullptr;
690 Value *TV = SI->getOperand(1);
691 Value *FV = SI->getOperand(2);
693 if (isa<Constant>(TV) || isa<Constant>(FV)) {
694 // Bool selects with constant operands can be folded to logical ops.
695 if (SI->getType()->isIntegerTy(1)) return nullptr;
697 // If it's a bitcast involving vectors, make sure it has the same number of
698 // elements on both sides.
699 if (BitCastInst *BC = dyn_cast<BitCastInst>(&Op)) {
700 VectorType *DestTy = dyn_cast<VectorType>(BC->getDestTy());
701 VectorType *SrcTy = dyn_cast<VectorType>(BC->getSrcTy());
703 // Verify that either both or neither are vectors.
704 if ((SrcTy == nullptr) != (DestTy == nullptr)) return nullptr;
705 // If vectors, verify that they have the same number of elements.
706 if (SrcTy && SrcTy->getNumElements() != DestTy->getNumElements())
710 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, this);
711 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, this);
713 return SelectInst::Create(SI->getCondition(),
714 SelectTrueVal, SelectFalseVal);
720 /// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
721 /// has a PHI node as operand #0, see if we can fold the instruction into the
722 /// PHI (which is only possible if all operands to the PHI are constants).
724 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
725 PHINode *PN = cast<PHINode>(I.getOperand(0));
726 unsigned NumPHIValues = PN->getNumIncomingValues();
727 if (NumPHIValues == 0)
730 // We normally only transform phis with a single use. However, if a PHI has
731 // multiple uses and they are all the same operation, we can fold *all* of the
732 // uses into the PHI.
733 if (!PN->hasOneUse()) {
734 // Walk the use list for the instruction, comparing them to I.
735 for (User *U : PN->users()) {
736 Instruction *UI = cast<Instruction>(U);
737 if (UI != &I && !I.isIdenticalTo(UI))
740 // Otherwise, we can replace *all* users with the new PHI we form.
743 // Check to see if all of the operands of the PHI are simple constants
744 // (constantint/constantfp/undef). If there is one non-constant value,
745 // remember the BB it is in. If there is more than one or if *it* is a PHI,
746 // bail out. We don't do arbitrary constant expressions here because moving
747 // their computation can be expensive without a cost model.
748 BasicBlock *NonConstBB = nullptr;
749 for (unsigned i = 0; i != NumPHIValues; ++i) {
750 Value *InVal = PN->getIncomingValue(i);
751 if (isa<Constant>(InVal) && !isa<ConstantExpr>(InVal))
754 if (isa<PHINode>(InVal)) return nullptr; // Itself a phi.
755 if (NonConstBB) return nullptr; // More than one non-const value.
757 NonConstBB = PN->getIncomingBlock(i);
759 // If the InVal is an invoke at the end of the pred block, then we can't
760 // insert a computation after it without breaking the edge.
761 if (InvokeInst *II = dyn_cast<InvokeInst>(InVal))
762 if (II->getParent() == NonConstBB)
765 // If the incoming non-constant value is in I's block, we will remove one
766 // instruction, but insert another equivalent one, leading to infinite
768 if (NonConstBB == I.getParent())
772 // If there is exactly one non-constant value, we can insert a copy of the
773 // operation in that block. However, if this is a critical edge, we would be
774 // inserting the computation one some other paths (e.g. inside a loop). Only
775 // do this if the pred block is unconditionally branching into the phi block.
776 if (NonConstBB != nullptr) {
777 BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
778 if (!BI || !BI->isUnconditional()) return nullptr;
781 // Okay, we can do the transformation: create the new PHI node.
782 PHINode *NewPN = PHINode::Create(I.getType(), PN->getNumIncomingValues());
783 InsertNewInstBefore(NewPN, *PN);
786 // If we are going to have to insert a new computation, do so right before the
787 // predecessors terminator.
789 Builder->SetInsertPoint(NonConstBB->getTerminator());
791 // Next, add all of the operands to the PHI.
792 if (SelectInst *SI = dyn_cast<SelectInst>(&I)) {
793 // We only currently try to fold the condition of a select when it is a phi,
794 // not the true/false values.
795 Value *TrueV = SI->getTrueValue();
796 Value *FalseV = SI->getFalseValue();
797 BasicBlock *PhiTransBB = PN->getParent();
798 for (unsigned i = 0; i != NumPHIValues; ++i) {
799 BasicBlock *ThisBB = PN->getIncomingBlock(i);
800 Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
801 Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
802 Value *InV = nullptr;
803 // Beware of ConstantExpr: it may eventually evaluate to getNullValue,
804 // even if currently isNullValue gives false.
805 Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i));
806 if (InC && !isa<ConstantExpr>(InC))
807 InV = InC->isNullValue() ? FalseVInPred : TrueVInPred;
809 InV = Builder->CreateSelect(PN->getIncomingValue(i),
810 TrueVInPred, FalseVInPred, "phitmp");
811 NewPN->addIncoming(InV, ThisBB);
813 } else if (CmpInst *CI = dyn_cast<CmpInst>(&I)) {
814 Constant *C = cast<Constant>(I.getOperand(1));
815 for (unsigned i = 0; i != NumPHIValues; ++i) {
816 Value *InV = nullptr;
817 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
818 InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
819 else if (isa<ICmpInst>(CI))
820 InV = Builder->CreateICmp(CI->getPredicate(), PN->getIncomingValue(i),
823 InV = Builder->CreateFCmp(CI->getPredicate(), PN->getIncomingValue(i),
825 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
827 } else if (I.getNumOperands() == 2) {
828 Constant *C = cast<Constant>(I.getOperand(1));
829 for (unsigned i = 0; i != NumPHIValues; ++i) {
830 Value *InV = nullptr;
831 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
832 InV = ConstantExpr::get(I.getOpcode(), InC, C);
834 InV = Builder->CreateBinOp(cast<BinaryOperator>(I).getOpcode(),
835 PN->getIncomingValue(i), C, "phitmp");
836 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
839 CastInst *CI = cast<CastInst>(&I);
840 Type *RetTy = CI->getType();
841 for (unsigned i = 0; i != NumPHIValues; ++i) {
843 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
844 InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
846 InV = Builder->CreateCast(CI->getOpcode(),
847 PN->getIncomingValue(i), I.getType(), "phitmp");
848 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
852 for (auto UI = PN->user_begin(), E = PN->user_end(); UI != E;) {
853 Instruction *User = cast<Instruction>(*UI++);
854 if (User == &I) continue;
855 ReplaceInstUsesWith(*User, NewPN);
856 EraseInstFromFunction(*User);
858 return ReplaceInstUsesWith(I, NewPN);
861 /// FindElementAtOffset - Given a pointer type and a constant offset, determine
862 /// whether or not there is a sequence of GEP indices into the pointed type that
863 /// will land us at the specified offset. If so, fill them into NewIndices and
864 /// return the resultant element type, otherwise return null.
865 Type *InstCombiner::FindElementAtOffset(Type *PtrTy, int64_t Offset,
866 SmallVectorImpl<Value*> &NewIndices) {
867 assert(PtrTy->isPtrOrPtrVectorTy());
872 Type *Ty = PtrTy->getPointerElementType();
876 // Start with the index over the outer type. Note that the type size
877 // might be zero (even if the offset isn't zero) if the indexed type
878 // is something like [0 x {int, int}]
879 Type *IntPtrTy = DL->getIntPtrType(PtrTy);
880 int64_t FirstIdx = 0;
881 if (int64_t TySize = DL->getTypeAllocSize(Ty)) {
882 FirstIdx = Offset/TySize;
883 Offset -= FirstIdx*TySize;
885 // Handle hosts where % returns negative instead of values [0..TySize).
891 assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset");
894 NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
896 // Index into the types. If we fail, set OrigBase to null.
898 // Indexing into tail padding between struct/array elements.
899 if (uint64_t(Offset*8) >= DL->getTypeSizeInBits(Ty))
902 if (StructType *STy = dyn_cast<StructType>(Ty)) {
903 const StructLayout *SL = DL->getStructLayout(STy);
904 assert(Offset < (int64_t)SL->getSizeInBytes() &&
905 "Offset must stay within the indexed type");
907 unsigned Elt = SL->getElementContainingOffset(Offset);
908 NewIndices.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
911 Offset -= SL->getElementOffset(Elt);
912 Ty = STy->getElementType(Elt);
913 } else if (ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
914 uint64_t EltSize = DL->getTypeAllocSize(AT->getElementType());
915 assert(EltSize && "Cannot index into a zero-sized array");
916 NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
918 Ty = AT->getElementType();
920 // Otherwise, we can't index into the middle of this atomic type, bail.
928 static bool shouldMergeGEPs(GEPOperator &GEP, GEPOperator &Src) {
929 // If this GEP has only 0 indices, it is the same pointer as
930 // Src. If Src is not a trivial GEP too, don't combine
932 if (GEP.hasAllZeroIndices() && !Src.hasAllZeroIndices() &&
938 /// Descale - Return a value X such that Val = X * Scale, or null if none. If
939 /// the multiplication is known not to overflow then NoSignedWrap is set.
940 Value *InstCombiner::Descale(Value *Val, APInt Scale, bool &NoSignedWrap) {
941 assert(isa<IntegerType>(Val->getType()) && "Can only descale integers!");
942 assert(cast<IntegerType>(Val->getType())->getBitWidth() ==
943 Scale.getBitWidth() && "Scale not compatible with value!");
945 // If Val is zero or Scale is one then Val = Val * Scale.
946 if (match(Val, m_Zero()) || Scale == 1) {
951 // If Scale is zero then it does not divide Val.
952 if (Scale.isMinValue())
955 // Look through chains of multiplications, searching for a constant that is
956 // divisible by Scale. For example, descaling X*(Y*(Z*4)) by a factor of 4
957 // will find the constant factor 4 and produce X*(Y*Z). Descaling X*(Y*8) by
958 // a factor of 4 will produce X*(Y*2). The principle of operation is to bore
961 // Val = M1 * X || Analysis starts here and works down
962 // M1 = M2 * Y || Doesn't descend into terms with more
963 // M2 = Z * 4 \/ than one use
965 // Then to modify a term at the bottom:
968 // M1 = Z * Y || Replaced M2 with Z
970 // Then to work back up correcting nsw flags.
972 // Op - the term we are currently analyzing. Starts at Val then drills down.
973 // Replaced with its descaled value before exiting from the drill down loop.
976 // Parent - initially null, but after drilling down notes where Op came from.
977 // In the example above, Parent is (Val, 0) when Op is M1, because M1 is the
978 // 0'th operand of Val.
979 std::pair<Instruction*, unsigned> Parent;
981 // RequireNoSignedWrap - Set if the transform requires a descaling at deeper
982 // levels that doesn't overflow.
983 bool RequireNoSignedWrap = false;
985 // logScale - log base 2 of the scale. Negative if not a power of 2.
986 int32_t logScale = Scale.exactLogBase2();
988 for (;; Op = Parent.first->getOperand(Parent.second)) { // Drill down
990 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
991 // If Op is a constant divisible by Scale then descale to the quotient.
992 APInt Quotient(Scale), Remainder(Scale); // Init ensures right bitwidth.
993 APInt::sdivrem(CI->getValue(), Scale, Quotient, Remainder);
994 if (!Remainder.isMinValue())
995 // Not divisible by Scale.
997 // Replace with the quotient in the parent.
998 Op = ConstantInt::get(CI->getType(), Quotient);
1003 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op)) {
1005 if (BO->getOpcode() == Instruction::Mul) {
1007 NoSignedWrap = BO->hasNoSignedWrap();
1008 if (RequireNoSignedWrap && !NoSignedWrap)
1011 // There are three cases for multiplication: multiplication by exactly
1012 // the scale, multiplication by a constant different to the scale, and
1013 // multiplication by something else.
1014 Value *LHS = BO->getOperand(0);
1015 Value *RHS = BO->getOperand(1);
1017 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1018 // Multiplication by a constant.
1019 if (CI->getValue() == Scale) {
1020 // Multiplication by exactly the scale, replace the multiplication
1021 // by its left-hand side in the parent.
1026 // Otherwise drill down into the constant.
1027 if (!Op->hasOneUse())
1030 Parent = std::make_pair(BO, 1);
1034 // Multiplication by something else. Drill down into the left-hand side
1035 // since that's where the reassociate pass puts the good stuff.
1036 if (!Op->hasOneUse())
1039 Parent = std::make_pair(BO, 0);
1043 if (logScale > 0 && BO->getOpcode() == Instruction::Shl &&
1044 isa<ConstantInt>(BO->getOperand(1))) {
1045 // Multiplication by a power of 2.
1046 NoSignedWrap = BO->hasNoSignedWrap();
1047 if (RequireNoSignedWrap && !NoSignedWrap)
1050 Value *LHS = BO->getOperand(0);
1051 int32_t Amt = cast<ConstantInt>(BO->getOperand(1))->
1052 getLimitedValue(Scale.getBitWidth());
1055 if (Amt == logScale) {
1056 // Multiplication by exactly the scale, replace the multiplication
1057 // by its left-hand side in the parent.
1061 if (Amt < logScale || !Op->hasOneUse())
1064 // Multiplication by more than the scale. Reduce the multiplying amount
1065 // by the scale in the parent.
1066 Parent = std::make_pair(BO, 1);
1067 Op = ConstantInt::get(BO->getType(), Amt - logScale);
1072 if (!Op->hasOneUse())
1075 if (CastInst *Cast = dyn_cast<CastInst>(Op)) {
1076 if (Cast->getOpcode() == Instruction::SExt) {
1077 // Op is sign-extended from a smaller type, descale in the smaller type.
1078 unsigned SmallSize = Cast->getSrcTy()->getPrimitiveSizeInBits();
1079 APInt SmallScale = Scale.trunc(SmallSize);
1080 // Suppose Op = sext X, and we descale X as Y * SmallScale. We want to
1081 // descale Op as (sext Y) * Scale. In order to have
1082 // sext (Y * SmallScale) = (sext Y) * Scale
1083 // some conditions need to hold however: SmallScale must sign-extend to
1084 // Scale and the multiplication Y * SmallScale should not overflow.
1085 if (SmallScale.sext(Scale.getBitWidth()) != Scale)
1086 // SmallScale does not sign-extend to Scale.
1088 assert(SmallScale.exactLogBase2() == logScale);
1089 // Require that Y * SmallScale must not overflow.
1090 RequireNoSignedWrap = true;
1092 // Drill down through the cast.
1093 Parent = std::make_pair(Cast, 0);
1098 if (Cast->getOpcode() == Instruction::Trunc) {
1099 // Op is truncated from a larger type, descale in the larger type.
1100 // Suppose Op = trunc X, and we descale X as Y * sext Scale. Then
1101 // trunc (Y * sext Scale) = (trunc Y) * Scale
1102 // always holds. However (trunc Y) * Scale may overflow even if
1103 // trunc (Y * sext Scale) does not, so nsw flags need to be cleared
1104 // from this point up in the expression (see later).
1105 if (RequireNoSignedWrap)
1108 // Drill down through the cast.
1109 unsigned LargeSize = Cast->getSrcTy()->getPrimitiveSizeInBits();
1110 Parent = std::make_pair(Cast, 0);
1111 Scale = Scale.sext(LargeSize);
1112 if (logScale + 1 == (int32_t)Cast->getType()->getPrimitiveSizeInBits())
1114 assert(Scale.exactLogBase2() == logScale);
1119 // Unsupported expression, bail out.
1123 // If Op is zero then Val = Op * Scale.
1124 if (match(Op, m_Zero())) {
1125 NoSignedWrap = true;
1129 // We know that we can successfully descale, so from here on we can safely
1130 // modify the IR. Op holds the descaled version of the deepest term in the
1131 // expression. NoSignedWrap is 'true' if multiplying Op by Scale is known
1135 // The expression only had one term.
1138 // Rewrite the parent using the descaled version of its operand.
1139 assert(Parent.first->hasOneUse() && "Drilled down when more than one use!");
1140 assert(Op != Parent.first->getOperand(Parent.second) &&
1141 "Descaling was a no-op?");
1142 Parent.first->setOperand(Parent.second, Op);
1143 Worklist.Add(Parent.first);
1145 // Now work back up the expression correcting nsw flags. The logic is based
1146 // on the following observation: if X * Y is known not to overflow as a signed
1147 // multiplication, and Y is replaced by a value Z with smaller absolute value,
1148 // then X * Z will not overflow as a signed multiplication either. As we work
1149 // our way up, having NoSignedWrap 'true' means that the descaled value at the
1150 // current level has strictly smaller absolute value than the original.
1151 Instruction *Ancestor = Parent.first;
1153 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Ancestor)) {
1154 // If the multiplication wasn't nsw then we can't say anything about the
1155 // value of the descaled multiplication, and we have to clear nsw flags
1156 // from this point on up.
1157 bool OpNoSignedWrap = BO->hasNoSignedWrap();
1158 NoSignedWrap &= OpNoSignedWrap;
1159 if (NoSignedWrap != OpNoSignedWrap) {
1160 BO->setHasNoSignedWrap(NoSignedWrap);
1161 Worklist.Add(Ancestor);
1163 } else if (Ancestor->getOpcode() == Instruction::Trunc) {
1164 // The fact that the descaled input to the trunc has smaller absolute
1165 // value than the original input doesn't tell us anything useful about
1166 // the absolute values of the truncations.
1167 NoSignedWrap = false;
1169 assert((Ancestor->getOpcode() != Instruction::SExt || NoSignedWrap) &&
1170 "Failed to keep proper track of nsw flags while drilling down?");
1172 if (Ancestor == Val)
1173 // Got to the top, all done!
1176 // Move up one level in the expression.
1177 assert(Ancestor->hasOneUse() && "Drilled down when more than one use!");
1178 Ancestor = Ancestor->user_back();
1182 /// \brief Creates node of binary operation with the same attributes as the
1183 /// specified one but with other operands.
1184 static Value *CreateBinOpAsGiven(BinaryOperator &Inst, Value *LHS, Value *RHS,
1185 InstCombiner::BuilderTy *B) {
1186 Value *BORes = B->CreateBinOp(Inst.getOpcode(), LHS, RHS);
1187 if (BinaryOperator *NewBO = dyn_cast<BinaryOperator>(BORes)) {
1188 if (isa<OverflowingBinaryOperator>(NewBO)) {
1189 NewBO->setHasNoSignedWrap(Inst.hasNoSignedWrap());
1190 NewBO->setHasNoUnsignedWrap(Inst.hasNoUnsignedWrap());
1192 if (isa<PossiblyExactOperator>(NewBO))
1193 NewBO->setIsExact(Inst.isExact());
1198 /// \brief Makes transformation of binary operation specific for vector types.
1199 /// \param Inst Binary operator to transform.
1200 /// \return Pointer to node that must replace the original binary operator, or
1201 /// null pointer if no transformation was made.
1202 Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) {
1203 if (!Inst.getType()->isVectorTy()) return nullptr;
1205 // It may not be safe to reorder shuffles and things like div, urem, etc.
1206 // because we may trap when executing those ops on unknown vector elements.
1208 if (!isSafeToSpeculativelyExecute(&Inst, DL)) return nullptr;
1210 unsigned VWidth = cast<VectorType>(Inst.getType())->getNumElements();
1211 Value *LHS = Inst.getOperand(0), *RHS = Inst.getOperand(1);
1212 assert(cast<VectorType>(LHS->getType())->getNumElements() == VWidth);
1213 assert(cast<VectorType>(RHS->getType())->getNumElements() == VWidth);
1215 // If both arguments of binary operation are shuffles, which use the same
1216 // mask and shuffle within a single vector, it is worthwhile to move the
1217 // shuffle after binary operation:
1218 // Op(shuffle(v1, m), shuffle(v2, m)) -> shuffle(Op(v1, v2), m)
1219 if (isa<ShuffleVectorInst>(LHS) && isa<ShuffleVectorInst>(RHS)) {
1220 ShuffleVectorInst *LShuf = cast<ShuffleVectorInst>(LHS);
1221 ShuffleVectorInst *RShuf = cast<ShuffleVectorInst>(RHS);
1222 if (isa<UndefValue>(LShuf->getOperand(1)) &&
1223 isa<UndefValue>(RShuf->getOperand(1)) &&
1224 LShuf->getOperand(0)->getType() == RShuf->getOperand(0)->getType() &&
1225 LShuf->getMask() == RShuf->getMask()) {
1226 Value *NewBO = CreateBinOpAsGiven(Inst, LShuf->getOperand(0),
1227 RShuf->getOperand(0), Builder);
1228 Value *Res = Builder->CreateShuffleVector(NewBO,
1229 UndefValue::get(NewBO->getType()), LShuf->getMask());
1234 // If one argument is a shuffle within one vector, the other is a constant,
1235 // try moving the shuffle after the binary operation.
1236 ShuffleVectorInst *Shuffle = nullptr;
1237 Constant *C1 = nullptr;
1238 if (isa<ShuffleVectorInst>(LHS)) Shuffle = cast<ShuffleVectorInst>(LHS);
1239 if (isa<ShuffleVectorInst>(RHS)) Shuffle = cast<ShuffleVectorInst>(RHS);
1240 if (isa<Constant>(LHS)) C1 = cast<Constant>(LHS);
1241 if (isa<Constant>(RHS)) C1 = cast<Constant>(RHS);
1242 if (Shuffle && C1 &&
1243 (isa<ConstantVector>(C1) || isa<ConstantDataVector>(C1)) &&
1244 isa<UndefValue>(Shuffle->getOperand(1)) &&
1245 Shuffle->getType() == Shuffle->getOperand(0)->getType()) {
1246 SmallVector<int, 16> ShMask = Shuffle->getShuffleMask();
1247 // Find constant C2 that has property:
1248 // shuffle(C2, ShMask) = C1
1249 // If such constant does not exist (example: ShMask=<0,0> and C1=<1,2>)
1250 // reorder is not possible.
1251 SmallVector<Constant*, 16> C2M(VWidth,
1252 UndefValue::get(C1->getType()->getScalarType()));
1253 bool MayChange = true;
1254 for (unsigned I = 0; I < VWidth; ++I) {
1255 if (ShMask[I] >= 0) {
1256 assert(ShMask[I] < (int)VWidth);
1257 if (!isa<UndefValue>(C2M[ShMask[I]])) {
1261 C2M[ShMask[I]] = C1->getAggregateElement(I);
1265 Constant *C2 = ConstantVector::get(C2M);
1266 Value *NewLHS, *NewRHS;
1267 if (isa<Constant>(LHS)) {
1269 NewRHS = Shuffle->getOperand(0);
1271 NewLHS = Shuffle->getOperand(0);
1274 Value *NewBO = CreateBinOpAsGiven(Inst, NewLHS, NewRHS, Builder);
1275 Value *Res = Builder->CreateShuffleVector(NewBO,
1276 UndefValue::get(Inst.getType()), Shuffle->getMask());
1284 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
1285 SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
1287 if (Value *V = SimplifyGEPInst(Ops, DL))
1288 return ReplaceInstUsesWith(GEP, V);
1290 Value *PtrOp = GEP.getOperand(0);
1292 // Eliminate unneeded casts for indices, and replace indices which displace
1293 // by multiples of a zero size type with zero.
1295 bool MadeChange = false;
1296 Type *IntPtrTy = DL->getIntPtrType(GEP.getPointerOperandType());
1298 gep_type_iterator GTI = gep_type_begin(GEP);
1299 for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end();
1300 I != E; ++I, ++GTI) {
1301 // Skip indices into struct types.
1302 SequentialType *SeqTy = dyn_cast<SequentialType>(*GTI);
1303 if (!SeqTy) continue;
1305 // If the element type has zero size then any index over it is equivalent
1306 // to an index of zero, so replace it with zero if it is not zero already.
1307 if (SeqTy->getElementType()->isSized() &&
1308 DL->getTypeAllocSize(SeqTy->getElementType()) == 0)
1309 if (!isa<Constant>(*I) || !cast<Constant>(*I)->isNullValue()) {
1310 *I = Constant::getNullValue(IntPtrTy);
1314 Type *IndexTy = (*I)->getType();
1315 if (IndexTy != IntPtrTy) {
1316 // If we are using a wider index than needed for this platform, shrink
1317 // it to what we need. If narrower, sign-extend it to what we need.
1318 // This explicit cast can make subsequent optimizations more obvious.
1319 *I = Builder->CreateIntCast(*I, IntPtrTy, true);
1323 if (MadeChange) return &GEP;
1326 // Check to see if the inputs to the PHI node are getelementptr instructions.
1327 if (PHINode *PN = dyn_cast<PHINode>(PtrOp)) {
1328 GetElementPtrInst *Op1 = dyn_cast<GetElementPtrInst>(PN->getOperand(0));
1334 for (auto I = PN->op_begin()+1, E = PN->op_end(); I !=E; ++I) {
1335 GetElementPtrInst *Op2 = dyn_cast<GetElementPtrInst>(*I);
1336 if (!Op2 || Op1->getNumOperands() != Op2->getNumOperands())
1339 // Keep track of the type as we walk the GEP.
1340 Type *CurTy = Op1->getOperand(0)->getType()->getScalarType();
1342 for (unsigned J = 0, F = Op1->getNumOperands(); J != F; ++J) {
1343 if (Op1->getOperand(J)->getType() != Op2->getOperand(J)->getType())
1346 if (Op1->getOperand(J) != Op2->getOperand(J)) {
1348 // We have not seen any differences yet in the GEPs feeding the
1349 // PHI yet, so we record this one if it is allowed to be a
1352 // The first two arguments can vary for any GEP, the rest have to be
1353 // static for struct slots
1354 if (J > 1 && CurTy->isStructTy())
1359 // The GEP is different by more than one input. While this could be
1360 // extended to support GEPs that vary by more than one variable it
1361 // doesn't make sense since it greatly increases the complexity and
1362 // would result in an R+R+R addressing mode which no backend
1363 // directly supports and would need to be broken into several
1364 // simpler instructions anyway.
1369 // Sink down a layer of the type for the next iteration.
1371 if (CompositeType *CT = dyn_cast<CompositeType>(CurTy)) {
1372 CurTy = CT->getTypeAtIndex(Op1->getOperand(J));
1380 GetElementPtrInst *NewGEP = cast<GetElementPtrInst>(Op1->clone());
1383 // All the GEPs feeding the PHI are identical. Clone one down into our
1384 // BB so that it can be merged with the current GEP.
1385 GEP.getParent()->getInstList().insert(GEP.getParent()->getFirstNonPHI(),
1388 // All the GEPs feeding the PHI differ at a single offset. Clone a GEP
1389 // into the current block so it can be merged, and create a new PHI to
1391 Instruction *InsertPt = Builder->GetInsertPoint();
1392 Builder->SetInsertPoint(PN);
1393 PHINode *NewPN = Builder->CreatePHI(Op1->getOperand(DI)->getType(),
1394 PN->getNumOperands());
1395 Builder->SetInsertPoint(InsertPt);
1397 for (auto &I : PN->operands())
1398 NewPN->addIncoming(cast<GEPOperator>(I)->getOperand(DI),
1399 PN->getIncomingBlock(I));
1401 NewGEP->setOperand(DI, NewPN);
1402 GEP.getParent()->getInstList().insert(GEP.getParent()->getFirstNonPHI(),
1404 NewGEP->setOperand(DI, NewPN);
1407 GEP.setOperand(0, NewGEP);
1411 // Combine Indices - If the source pointer to this getelementptr instruction
1412 // is a getelementptr instruction, combine the indices of the two
1413 // getelementptr instructions into a single instruction.
1415 if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
1416 if (!shouldMergeGEPs(*cast<GEPOperator>(&GEP), *Src))
1419 // Note that if our source is a gep chain itself then we wait for that
1420 // chain to be resolved before we perform this transformation. This
1421 // avoids us creating a TON of code in some cases.
1422 if (GEPOperator *SrcGEP =
1423 dyn_cast<GEPOperator>(Src->getOperand(0)))
1424 if (SrcGEP->getNumOperands() == 2 && shouldMergeGEPs(*Src, *SrcGEP))
1425 return nullptr; // Wait until our source is folded to completion.
1427 SmallVector<Value*, 8> Indices;
1429 // Find out whether the last index in the source GEP is a sequential idx.
1430 bool EndsWithSequential = false;
1431 for (gep_type_iterator I = gep_type_begin(*Src), E = gep_type_end(*Src);
1433 EndsWithSequential = !(*I)->isStructTy();
1435 // Can we combine the two pointer arithmetics offsets?
1436 if (EndsWithSequential) {
1437 // Replace: gep (gep %P, long B), long A, ...
1438 // With: T = long A+B; gep %P, T, ...
1441 Value *SO1 = Src->getOperand(Src->getNumOperands()-1);
1442 Value *GO1 = GEP.getOperand(1);
1443 if (SO1 == Constant::getNullValue(SO1->getType())) {
1445 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
1448 // If they aren't the same type, then the input hasn't been processed
1449 // by the loop above yet (which canonicalizes sequential index types to
1450 // intptr_t). Just avoid transforming this until the input has been
1452 if (SO1->getType() != GO1->getType())
1454 Sum = Builder->CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
1457 // Update the GEP in place if possible.
1458 if (Src->getNumOperands() == 2) {
1459 GEP.setOperand(0, Src->getOperand(0));
1460 GEP.setOperand(1, Sum);
1463 Indices.append(Src->op_begin()+1, Src->op_end()-1);
1464 Indices.push_back(Sum);
1465 Indices.append(GEP.op_begin()+2, GEP.op_end());
1466 } else if (isa<Constant>(*GEP.idx_begin()) &&
1467 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
1468 Src->getNumOperands() != 1) {
1469 // Otherwise we can do the fold if the first index of the GEP is a zero
1470 Indices.append(Src->op_begin()+1, Src->op_end());
1471 Indices.append(GEP.idx_begin()+1, GEP.idx_end());
1474 if (!Indices.empty())
1475 return (GEP.isInBounds() && Src->isInBounds()) ?
1476 GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices,
1478 GetElementPtrInst::Create(Src->getOperand(0), Indices, GEP.getName());
1481 // Canonicalize (gep i8* X, -(ptrtoint Y)) to (sub (ptrtoint X), (ptrtoint Y))
1482 // The GEP pattern is emitted by the SCEV expander for certain kinds of
1483 // pointer arithmetic.
1484 if (DL && GEP.getNumIndices() == 1 &&
1485 match(GEP.getOperand(1), m_Neg(m_PtrToInt(m_Value())))) {
1486 unsigned AS = GEP.getPointerAddressSpace();
1487 if (GEP.getType() == Builder->getInt8PtrTy(AS) &&
1488 GEP.getOperand(1)->getType()->getScalarSizeInBits() ==
1489 DL->getPointerSizeInBits(AS)) {
1490 Operator *Index = cast<Operator>(GEP.getOperand(1));
1491 Value *PtrToInt = Builder->CreatePtrToInt(PtrOp, Index->getType());
1492 Value *NewSub = Builder->CreateSub(PtrToInt, Index->getOperand(1));
1493 return CastInst::Create(Instruction::IntToPtr, NewSub, GEP.getType());
1497 // Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
1498 Value *StrippedPtr = PtrOp->stripPointerCasts();
1499 PointerType *StrippedPtrTy = dyn_cast<PointerType>(StrippedPtr->getType());
1501 // We do not handle pointer-vector geps here.
1505 if (StrippedPtr != PtrOp) {
1506 bool HasZeroPointerIndex = false;
1507 if (ConstantInt *C = dyn_cast<ConstantInt>(GEP.getOperand(1)))
1508 HasZeroPointerIndex = C->isZero();
1510 // Transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
1511 // into : GEP [10 x i8]* X, i32 0, ...
1513 // Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
1514 // into : GEP i8* X, ...
1516 // This occurs when the program declares an array extern like "int X[];"
1517 if (HasZeroPointerIndex) {
1518 PointerType *CPTy = cast<PointerType>(PtrOp->getType());
1519 if (ArrayType *CATy =
1520 dyn_cast<ArrayType>(CPTy->getElementType())) {
1521 // GEP (bitcast i8* X to [0 x i8]*), i32 0, ... ?
1522 if (CATy->getElementType() == StrippedPtrTy->getElementType()) {
1523 // -> GEP i8* X, ...
1524 SmallVector<Value*, 8> Idx(GEP.idx_begin()+1, GEP.idx_end());
1525 GetElementPtrInst *Res =
1526 GetElementPtrInst::Create(StrippedPtr, Idx, GEP.getName());
1527 Res->setIsInBounds(GEP.isInBounds());
1528 if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace())
1530 // Insert Res, and create an addrspacecast.
1532 // GEP (addrspacecast i8 addrspace(1)* X to [0 x i8]*), i32 0, ...
1534 // %0 = GEP i8 addrspace(1)* X, ...
1535 // addrspacecast i8 addrspace(1)* %0 to i8*
1536 return new AddrSpaceCastInst(Builder->Insert(Res), GEP.getType());
1539 if (ArrayType *XATy =
1540 dyn_cast<ArrayType>(StrippedPtrTy->getElementType())){
1541 // GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ?
1542 if (CATy->getElementType() == XATy->getElementType()) {
1543 // -> GEP [10 x i8]* X, i32 0, ...
1544 // At this point, we know that the cast source type is a pointer
1545 // to an array of the same type as the destination pointer
1546 // array. Because the array type is never stepped over (there
1547 // is a leading zero) we can fold the cast into this GEP.
1548 if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace()) {
1549 GEP.setOperand(0, StrippedPtr);
1552 // Cannot replace the base pointer directly because StrippedPtr's
1553 // address space is different. Instead, create a new GEP followed by
1554 // an addrspacecast.
1556 // GEP (addrspacecast [10 x i8] addrspace(1)* X to [0 x i8]*),
1559 // %0 = GEP [10 x i8] addrspace(1)* X, ...
1560 // addrspacecast i8 addrspace(1)* %0 to i8*
1561 SmallVector<Value*, 8> Idx(GEP.idx_begin(), GEP.idx_end());
1562 Value *NewGEP = GEP.isInBounds() ?
1563 Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) :
1564 Builder->CreateGEP(StrippedPtr, Idx, GEP.getName());
1565 return new AddrSpaceCastInst(NewGEP, GEP.getType());
1569 } else if (GEP.getNumOperands() == 2) {
1570 // Transform things like:
1571 // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
1572 // into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
1573 Type *SrcElTy = StrippedPtrTy->getElementType();
1574 Type *ResElTy = PtrOp->getType()->getPointerElementType();
1575 if (DL && SrcElTy->isArrayTy() &&
1576 DL->getTypeAllocSize(SrcElTy->getArrayElementType()) ==
1577 DL->getTypeAllocSize(ResElTy)) {
1578 Type *IdxType = DL->getIntPtrType(GEP.getType());
1579 Value *Idx[2] = { Constant::getNullValue(IdxType), GEP.getOperand(1) };
1580 Value *NewGEP = GEP.isInBounds() ?
1581 Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) :
1582 Builder->CreateGEP(StrippedPtr, Idx, GEP.getName());
1584 // V and GEP are both pointer types --> BitCast
1585 return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
1589 // Transform things like:
1590 // %V = mul i64 %N, 4
1591 // %t = getelementptr i8* bitcast (i32* %arr to i8*), i32 %V
1592 // into: %t1 = getelementptr i32* %arr, i32 %N; bitcast
1593 if (DL && ResElTy->isSized() && SrcElTy->isSized()) {
1594 // Check that changing the type amounts to dividing the index by a scale
1596 uint64_t ResSize = DL->getTypeAllocSize(ResElTy);
1597 uint64_t SrcSize = DL->getTypeAllocSize(SrcElTy);
1598 if (ResSize && SrcSize % ResSize == 0) {
1599 Value *Idx = GEP.getOperand(1);
1600 unsigned BitWidth = Idx->getType()->getPrimitiveSizeInBits();
1601 uint64_t Scale = SrcSize / ResSize;
1603 // Earlier transforms ensure that the index has type IntPtrType, which
1604 // considerably simplifies the logic by eliminating implicit casts.
1605 assert(Idx->getType() == DL->getIntPtrType(GEP.getType()) &&
1606 "Index not cast to pointer width?");
1609 if (Value *NewIdx = Descale(Idx, APInt(BitWidth, Scale), NSW)) {
1610 // Successfully decomposed Idx as NewIdx * Scale, form a new GEP.
1611 // If the multiplication NewIdx * Scale may overflow then the new
1612 // GEP may not be "inbounds".
1613 Value *NewGEP = GEP.isInBounds() && NSW ?
1614 Builder->CreateInBoundsGEP(StrippedPtr, NewIdx, GEP.getName()) :
1615 Builder->CreateGEP(StrippedPtr, NewIdx, GEP.getName());
1617 // The NewGEP must be pointer typed, so must the old one -> BitCast
1618 return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
1624 // Similarly, transform things like:
1625 // getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
1626 // (where tmp = 8*tmp2) into:
1627 // getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
1628 if (DL && ResElTy->isSized() && SrcElTy->isSized() &&
1629 SrcElTy->isArrayTy()) {
1630 // Check that changing to the array element type amounts to dividing the
1631 // index by a scale factor.
1632 uint64_t ResSize = DL->getTypeAllocSize(ResElTy);
1633 uint64_t ArrayEltSize
1634 = DL->getTypeAllocSize(SrcElTy->getArrayElementType());
1635 if (ResSize && ArrayEltSize % ResSize == 0) {
1636 Value *Idx = GEP.getOperand(1);
1637 unsigned BitWidth = Idx->getType()->getPrimitiveSizeInBits();
1638 uint64_t Scale = ArrayEltSize / ResSize;
1640 // Earlier transforms ensure that the index has type IntPtrType, which
1641 // considerably simplifies the logic by eliminating implicit casts.
1642 assert(Idx->getType() == DL->getIntPtrType(GEP.getType()) &&
1643 "Index not cast to pointer width?");
1646 if (Value *NewIdx = Descale(Idx, APInt(BitWidth, Scale), NSW)) {
1647 // Successfully decomposed Idx as NewIdx * Scale, form a new GEP.
1648 // If the multiplication NewIdx * Scale may overflow then the new
1649 // GEP may not be "inbounds".
1651 Constant::getNullValue(DL->getIntPtrType(GEP.getType())),
1655 Value *NewGEP = GEP.isInBounds() && NSW ?
1656 Builder->CreateInBoundsGEP(StrippedPtr, Off, GEP.getName()) :
1657 Builder->CreateGEP(StrippedPtr, Off, GEP.getName());
1658 // The NewGEP must be pointer typed, so must the old one -> BitCast
1659 return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
1670 /// See if we can simplify:
1671 /// X = bitcast A* to B*
1672 /// Y = gep X, <...constant indices...>
1673 /// into a gep of the original struct. This is important for SROA and alias
1674 /// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
1675 if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
1676 Value *Operand = BCI->getOperand(0);
1677 PointerType *OpType = cast<PointerType>(Operand->getType());
1678 unsigned OffsetBits = DL->getPointerTypeSizeInBits(OpType);
1679 APInt Offset(OffsetBits, 0);
1680 if (!isa<BitCastInst>(Operand) &&
1681 GEP.accumulateConstantOffset(*DL, Offset) &&
1682 StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
1684 // If this GEP instruction doesn't move the pointer, just replace the GEP
1685 // with a bitcast of the real input to the dest type.
1687 // If the bitcast is of an allocation, and the allocation will be
1688 // converted to match the type of the cast, don't touch this.
1689 if (isa<AllocaInst>(Operand) || isAllocationFn(Operand, TLI)) {
1690 // See if the bitcast simplifies, if so, don't nuke this GEP yet.
1691 if (Instruction *I = visitBitCast(*BCI)) {
1694 BCI->getParent()->getInstList().insert(BCI, I);
1695 ReplaceInstUsesWith(*BCI, I);
1700 return new BitCastInst(Operand, GEP.getType());
1703 // Otherwise, if the offset is non-zero, we need to find out if there is a
1704 // field at Offset in 'A's type. If so, we can pull the cast through the
1706 SmallVector<Value*, 8> NewIndices;
1707 if (FindElementAtOffset(OpType, Offset.getSExtValue(), NewIndices)) {
1708 Value *NGEP = GEP.isInBounds() ?
1709 Builder->CreateInBoundsGEP(Operand, NewIndices) :
1710 Builder->CreateGEP(Operand, NewIndices);
1712 if (NGEP->getType() == GEP.getType())
1713 return ReplaceInstUsesWith(GEP, NGEP);
1714 NGEP->takeName(&GEP);
1715 return new BitCastInst(NGEP, GEP.getType());
1724 isAllocSiteRemovable(Instruction *AI, SmallVectorImpl<WeakVH> &Users,
1725 const TargetLibraryInfo *TLI) {
1726 SmallVector<Instruction*, 4> Worklist;
1727 Worklist.push_back(AI);
1730 Instruction *PI = Worklist.pop_back_val();
1731 for (User *U : PI->users()) {
1732 Instruction *I = cast<Instruction>(U);
1733 switch (I->getOpcode()) {
1735 // Give up the moment we see something we can't handle.
1738 case Instruction::BitCast:
1739 case Instruction::GetElementPtr:
1741 Worklist.push_back(I);
1744 case Instruction::ICmp: {
1745 ICmpInst *ICI = cast<ICmpInst>(I);
1746 // We can fold eq/ne comparisons with null to false/true, respectively.
1747 if (!ICI->isEquality() || !isa<ConstantPointerNull>(ICI->getOperand(1)))
1753 case Instruction::Call:
1754 // Ignore no-op and store intrinsics.
1755 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
1756 switch (II->getIntrinsicID()) {
1760 case Intrinsic::memmove:
1761 case Intrinsic::memcpy:
1762 case Intrinsic::memset: {
1763 MemIntrinsic *MI = cast<MemIntrinsic>(II);
1764 if (MI->isVolatile() || MI->getRawDest() != PI)
1768 case Intrinsic::dbg_declare:
1769 case Intrinsic::dbg_value:
1770 case Intrinsic::invariant_start:
1771 case Intrinsic::invariant_end:
1772 case Intrinsic::lifetime_start:
1773 case Intrinsic::lifetime_end:
1774 case Intrinsic::objectsize:
1780 if (isFreeCall(I, TLI)) {
1786 case Instruction::Store: {
1787 StoreInst *SI = cast<StoreInst>(I);
1788 if (SI->isVolatile() || SI->getPointerOperand() != PI)
1794 llvm_unreachable("missing a return?");
1796 } while (!Worklist.empty());
1800 Instruction *InstCombiner::visitAllocSite(Instruction &MI) {
1801 // If we have a malloc call which is only used in any amount of comparisons
1802 // to null and free calls, delete the calls and replace the comparisons with
1803 // true or false as appropriate.
1804 SmallVector<WeakVH, 64> Users;
1805 if (isAllocSiteRemovable(&MI, Users, TLI)) {
1806 for (unsigned i = 0, e = Users.size(); i != e; ++i) {
1807 Instruction *I = cast_or_null<Instruction>(&*Users[i]);
1810 if (ICmpInst *C = dyn_cast<ICmpInst>(I)) {
1811 ReplaceInstUsesWith(*C,
1812 ConstantInt::get(Type::getInt1Ty(C->getContext()),
1813 C->isFalseWhenEqual()));
1814 } else if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I)) {
1815 ReplaceInstUsesWith(*I, UndefValue::get(I->getType()));
1816 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
1817 if (II->getIntrinsicID() == Intrinsic::objectsize) {
1818 ConstantInt *CI = cast<ConstantInt>(II->getArgOperand(1));
1819 uint64_t DontKnow = CI->isZero() ? -1ULL : 0;
1820 ReplaceInstUsesWith(*I, ConstantInt::get(I->getType(), DontKnow));
1823 EraseInstFromFunction(*I);
1826 if (InvokeInst *II = dyn_cast<InvokeInst>(&MI)) {
1827 // Replace invoke with a NOP intrinsic to maintain the original CFG
1828 Module *M = II->getParent()->getParent()->getParent();
1829 Function *F = Intrinsic::getDeclaration(M, Intrinsic::donothing);
1830 InvokeInst::Create(F, II->getNormalDest(), II->getUnwindDest(),
1831 None, "", II->getParent());
1833 return EraseInstFromFunction(MI);
1838 /// \brief Move the call to free before a NULL test.
1840 /// Check if this free is accessed after its argument has been test
1841 /// against NULL (property 0).
1842 /// If yes, it is legal to move this call in its predecessor block.
1844 /// The move is performed only if the block containing the call to free
1845 /// will be removed, i.e.:
1846 /// 1. it has only one predecessor P, and P has two successors
1847 /// 2. it contains the call and an unconditional branch
1848 /// 3. its successor is the same as its predecessor's successor
1850 /// The profitability is out-of concern here and this function should
1851 /// be called only if the caller knows this transformation would be
1852 /// profitable (e.g., for code size).
1853 static Instruction *
1854 tryToMoveFreeBeforeNullTest(CallInst &FI) {
1855 Value *Op = FI.getArgOperand(0);
1856 BasicBlock *FreeInstrBB = FI.getParent();
1857 BasicBlock *PredBB = FreeInstrBB->getSinglePredecessor();
1859 // Validate part of constraint #1: Only one predecessor
1860 // FIXME: We can extend the number of predecessor, but in that case, we
1861 // would duplicate the call to free in each predecessor and it may
1862 // not be profitable even for code size.
1866 // Validate constraint #2: Does this block contains only the call to
1867 // free and an unconditional branch?
1868 // FIXME: We could check if we can speculate everything in the
1869 // predecessor block
1870 if (FreeInstrBB->size() != 2)
1873 if (!match(FreeInstrBB->getTerminator(), m_UnconditionalBr(SuccBB)))
1876 // Validate the rest of constraint #1 by matching on the pred branch.
1877 TerminatorInst *TI = PredBB->getTerminator();
1878 BasicBlock *TrueBB, *FalseBB;
1879 ICmpInst::Predicate Pred;
1880 if (!match(TI, m_Br(m_ICmp(Pred, m_Specific(Op), m_Zero()), TrueBB, FalseBB)))
1882 if (Pred != ICmpInst::ICMP_EQ && Pred != ICmpInst::ICMP_NE)
1885 // Validate constraint #3: Ensure the null case just falls through.
1886 if (SuccBB != (Pred == ICmpInst::ICMP_EQ ? TrueBB : FalseBB))
1888 assert(FreeInstrBB == (Pred == ICmpInst::ICMP_EQ ? FalseBB : TrueBB) &&
1889 "Broken CFG: missing edge from predecessor to successor");
1896 Instruction *InstCombiner::visitFree(CallInst &FI) {
1897 Value *Op = FI.getArgOperand(0);
1899 // free undef -> unreachable.
1900 if (isa<UndefValue>(Op)) {
1901 // Insert a new store to null because we cannot modify the CFG here.
1902 Builder->CreateStore(ConstantInt::getTrue(FI.getContext()),
1903 UndefValue::get(Type::getInt1PtrTy(FI.getContext())));
1904 return EraseInstFromFunction(FI);
1907 // If we have 'free null' delete the instruction. This can happen in stl code
1908 // when lots of inlining happens.
1909 if (isa<ConstantPointerNull>(Op))
1910 return EraseInstFromFunction(FI);
1912 // If we optimize for code size, try to move the call to free before the null
1913 // test so that simplify cfg can remove the empty block and dead code
1914 // elimination the branch. I.e., helps to turn something like:
1915 // if (foo) free(foo);
1919 if (Instruction *I = tryToMoveFreeBeforeNullTest(FI))
1927 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
1928 // Change br (not X), label True, label False to: br X, label False, True
1930 BasicBlock *TrueDest;
1931 BasicBlock *FalseDest;
1932 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
1933 !isa<Constant>(X)) {
1934 // Swap Destinations and condition...
1936 BI.swapSuccessors();
1940 // Canonicalize fcmp_one -> fcmp_oeq
1941 FCmpInst::Predicate FPred; Value *Y;
1942 if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
1943 TrueDest, FalseDest)) &&
1944 BI.getCondition()->hasOneUse())
1945 if (FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
1946 FPred == FCmpInst::FCMP_OGE) {
1947 FCmpInst *Cond = cast<FCmpInst>(BI.getCondition());
1948 Cond->setPredicate(FCmpInst::getInversePredicate(FPred));
1950 // Swap Destinations and condition.
1951 BI.swapSuccessors();
1956 // Canonicalize icmp_ne -> icmp_eq
1957 ICmpInst::Predicate IPred;
1958 if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
1959 TrueDest, FalseDest)) &&
1960 BI.getCondition()->hasOneUse())
1961 if (IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
1962 IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
1963 IPred == ICmpInst::ICMP_SGE) {
1964 ICmpInst *Cond = cast<ICmpInst>(BI.getCondition());
1965 Cond->setPredicate(ICmpInst::getInversePredicate(IPred));
1966 // Swap Destinations and condition.
1967 BI.swapSuccessors();
1975 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
1976 Value *Cond = SI.getCondition();
1977 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
1978 if (I->getOpcode() == Instruction::Add)
1979 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
1980 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
1981 // Skip the first item since that's the default case.
1982 for (SwitchInst::CaseIt i = SI.case_begin(), e = SI.case_end();
1984 ConstantInt* CaseVal = i.getCaseValue();
1985 Constant* NewCaseVal = ConstantExpr::getSub(cast<Constant>(CaseVal),
1987 assert(isa<ConstantInt>(NewCaseVal) &&
1988 "Result of expression should be constant");
1989 i.setValue(cast<ConstantInt>(NewCaseVal));
1991 SI.setCondition(I->getOperand(0));
1999 Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
2000 Value *Agg = EV.getAggregateOperand();
2002 if (!EV.hasIndices())
2003 return ReplaceInstUsesWith(EV, Agg);
2005 if (Constant *C = dyn_cast<Constant>(Agg)) {
2006 if (Constant *C2 = C->getAggregateElement(*EV.idx_begin())) {
2007 if (EV.getNumIndices() == 0)
2008 return ReplaceInstUsesWith(EV, C2);
2009 // Extract the remaining indices out of the constant indexed by the
2011 return ExtractValueInst::Create(C2, EV.getIndices().slice(1));
2013 return nullptr; // Can't handle other constants
2016 if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
2017 // We're extracting from an insertvalue instruction, compare the indices
2018 const unsigned *exti, *exte, *insi, *inse;
2019 for (exti = EV.idx_begin(), insi = IV->idx_begin(),
2020 exte = EV.idx_end(), inse = IV->idx_end();
2021 exti != exte && insi != inse;
2024 // The insert and extract both reference distinctly different elements.
2025 // This means the extract is not influenced by the insert, and we can
2026 // replace the aggregate operand of the extract with the aggregate
2027 // operand of the insert. i.e., replace
2028 // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
2029 // %E = extractvalue { i32, { i32 } } %I, 0
2031 // %E = extractvalue { i32, { i32 } } %A, 0
2032 return ExtractValueInst::Create(IV->getAggregateOperand(),
2035 if (exti == exte && insi == inse)
2036 // Both iterators are at the end: Index lists are identical. Replace
2037 // %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
2038 // %C = extractvalue { i32, { i32 } } %B, 1, 0
2040 return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand());
2042 // The extract list is a prefix of the insert list. i.e. replace
2043 // %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
2044 // %E = extractvalue { i32, { i32 } } %I, 1
2046 // %X = extractvalue { i32, { i32 } } %A, 1
2047 // %E = insertvalue { i32 } %X, i32 42, 0
2048 // by switching the order of the insert and extract (though the
2049 // insertvalue should be left in, since it may have other uses).
2050 Value *NewEV = Builder->CreateExtractValue(IV->getAggregateOperand(),
2052 return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(),
2053 makeArrayRef(insi, inse));
2056 // The insert list is a prefix of the extract list
2057 // We can simply remove the common indices from the extract and make it
2058 // operate on the inserted value instead of the insertvalue result.
2060 // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
2061 // %E = extractvalue { i32, { i32 } } %I, 1, 0
2063 // %E extractvalue { i32 } { i32 42 }, 0
2064 return ExtractValueInst::Create(IV->getInsertedValueOperand(),
2065 makeArrayRef(exti, exte));
2067 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Agg)) {
2068 // We're extracting from an intrinsic, see if we're the only user, which
2069 // allows us to simplify multiple result intrinsics to simpler things that
2070 // just get one value.
2071 if (II->hasOneUse()) {
2072 // Check if we're grabbing the overflow bit or the result of a 'with
2073 // overflow' intrinsic. If it's the latter we can remove the intrinsic
2074 // and replace it with a traditional binary instruction.
2075 switch (II->getIntrinsicID()) {
2076 case Intrinsic::uadd_with_overflow:
2077 case Intrinsic::sadd_with_overflow:
2078 if (*EV.idx_begin() == 0) { // Normal result.
2079 Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
2080 ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
2081 EraseInstFromFunction(*II);
2082 return BinaryOperator::CreateAdd(LHS, RHS);
2085 // If the normal result of the add is dead, and the RHS is a constant,
2086 // we can transform this into a range comparison.
2087 // overflow = uadd a, -4 --> overflow = icmp ugt a, 3
2088 if (II->getIntrinsicID() == Intrinsic::uadd_with_overflow)
2089 if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getArgOperand(1)))
2090 return new ICmpInst(ICmpInst::ICMP_UGT, II->getArgOperand(0),
2091 ConstantExpr::getNot(CI));
2093 case Intrinsic::usub_with_overflow:
2094 case Intrinsic::ssub_with_overflow:
2095 if (*EV.idx_begin() == 0) { // Normal result.
2096 Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
2097 ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
2098 EraseInstFromFunction(*II);
2099 return BinaryOperator::CreateSub(LHS, RHS);
2102 case Intrinsic::umul_with_overflow:
2103 case Intrinsic::smul_with_overflow:
2104 if (*EV.idx_begin() == 0) { // Normal result.
2105 Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
2106 ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
2107 EraseInstFromFunction(*II);
2108 return BinaryOperator::CreateMul(LHS, RHS);
2116 if (LoadInst *L = dyn_cast<LoadInst>(Agg))
2117 // If the (non-volatile) load only has one use, we can rewrite this to a
2118 // load from a GEP. This reduces the size of the load.
2119 // FIXME: If a load is used only by extractvalue instructions then this
2120 // could be done regardless of having multiple uses.
2121 if (L->isSimple() && L->hasOneUse()) {
2122 // extractvalue has integer indices, getelementptr has Value*s. Convert.
2123 SmallVector<Value*, 4> Indices;
2124 // Prefix an i32 0 since we need the first element.
2125 Indices.push_back(Builder->getInt32(0));
2126 for (ExtractValueInst::idx_iterator I = EV.idx_begin(), E = EV.idx_end();
2128 Indices.push_back(Builder->getInt32(*I));
2130 // We need to insert these at the location of the old load, not at that of
2131 // the extractvalue.
2132 Builder->SetInsertPoint(L->getParent(), L);
2133 Value *GEP = Builder->CreateInBoundsGEP(L->getPointerOperand(), Indices);
2134 // Returning the load directly will cause the main loop to insert it in
2135 // the wrong spot, so use ReplaceInstUsesWith().
2136 return ReplaceInstUsesWith(EV, Builder->CreateLoad(GEP));
2138 // We could simplify extracts from other values. Note that nested extracts may
2139 // already be simplified implicitly by the above: extract (extract (insert) )
2140 // will be translated into extract ( insert ( extract ) ) first and then just
2141 // the value inserted, if appropriate. Similarly for extracts from single-use
2142 // loads: extract (extract (load)) will be translated to extract (load (gep))
2143 // and if again single-use then via load (gep (gep)) to load (gep).
2144 // However, double extracts from e.g. function arguments or return values
2145 // aren't handled yet.
2149 enum Personality_Type {
2150 Unknown_Personality,
2151 GNU_Ada_Personality,
2152 GNU_CXX_Personality,
2153 GNU_ObjC_Personality
2156 /// RecognizePersonality - See if the given exception handling personality
2157 /// function is one that we understand. If so, return a description of it;
2158 /// otherwise return Unknown_Personality.
2159 static Personality_Type RecognizePersonality(Value *Pers) {
2160 Function *F = dyn_cast<Function>(Pers->stripPointerCasts());
2162 return Unknown_Personality;
2163 return StringSwitch<Personality_Type>(F->getName())
2164 .Case("__gnat_eh_personality", GNU_Ada_Personality)
2165 .Case("__gxx_personality_v0", GNU_CXX_Personality)
2166 .Case("__objc_personality_v0", GNU_ObjC_Personality)
2167 .Default(Unknown_Personality);
2170 /// isCatchAll - Return 'true' if the given typeinfo will match anything.
2171 static bool isCatchAll(Personality_Type Personality, Constant *TypeInfo) {
2172 switch (Personality) {
2173 case Unknown_Personality:
2175 case GNU_Ada_Personality:
2176 // While __gnat_all_others_value will match any Ada exception, it doesn't
2177 // match foreign exceptions (or didn't, before gcc-4.7).
2179 case GNU_CXX_Personality:
2180 case GNU_ObjC_Personality:
2181 return TypeInfo->isNullValue();
2183 llvm_unreachable("Unknown personality!");
2186 static bool shorter_filter(const Value *LHS, const Value *RHS) {
2188 cast<ArrayType>(LHS->getType())->getNumElements()
2190 cast<ArrayType>(RHS->getType())->getNumElements();
2193 Instruction *InstCombiner::visitLandingPadInst(LandingPadInst &LI) {
2194 // The logic here should be correct for any real-world personality function.
2195 // However if that turns out not to be true, the offending logic can always
2196 // be conditioned on the personality function, like the catch-all logic is.
2197 Personality_Type Personality = RecognizePersonality(LI.getPersonalityFn());
2199 // Simplify the list of clauses, eg by removing repeated catch clauses
2200 // (these are often created by inlining).
2201 bool MakeNewInstruction = false; // If true, recreate using the following:
2202 SmallVector<Constant *, 16> NewClauses; // - Clauses for the new instruction;
2203 bool CleanupFlag = LI.isCleanup(); // - The new instruction is a cleanup.
2205 SmallPtrSet<Value *, 16> AlreadyCaught; // Typeinfos known caught already.
2206 for (unsigned i = 0, e = LI.getNumClauses(); i != e; ++i) {
2207 bool isLastClause = i + 1 == e;
2208 if (LI.isCatch(i)) {
2210 Constant *CatchClause = LI.getClause(i);
2211 Constant *TypeInfo = CatchClause->stripPointerCasts();
2213 // If we already saw this clause, there is no point in having a second
2215 if (AlreadyCaught.insert(TypeInfo)) {
2216 // This catch clause was not already seen.
2217 NewClauses.push_back(CatchClause);
2219 // Repeated catch clause - drop the redundant copy.
2220 MakeNewInstruction = true;
2223 // If this is a catch-all then there is no point in keeping any following
2224 // clauses or marking the landingpad as having a cleanup.
2225 if (isCatchAll(Personality, TypeInfo)) {
2227 MakeNewInstruction = true;
2228 CleanupFlag = false;
2232 // A filter clause. If any of the filter elements were already caught
2233 // then they can be dropped from the filter. It is tempting to try to
2234 // exploit the filter further by saying that any typeinfo that does not
2235 // occur in the filter can't be caught later (and thus can be dropped).
2236 // However this would be wrong, since typeinfos can match without being
2237 // equal (for example if one represents a C++ class, and the other some
2238 // class derived from it).
2239 assert(LI.isFilter(i) && "Unsupported landingpad clause!");
2240 Constant *FilterClause = LI.getClause(i);
2241 ArrayType *FilterType = cast<ArrayType>(FilterClause->getType());
2242 unsigned NumTypeInfos = FilterType->getNumElements();
2244 // An empty filter catches everything, so there is no point in keeping any
2245 // following clauses or marking the landingpad as having a cleanup. By
2246 // dealing with this case here the following code is made a bit simpler.
2247 if (!NumTypeInfos) {
2248 NewClauses.push_back(FilterClause);
2250 MakeNewInstruction = true;
2251 CleanupFlag = false;
2255 bool MakeNewFilter = false; // If true, make a new filter.
2256 SmallVector<Constant *, 16> NewFilterElts; // New elements.
2257 if (isa<ConstantAggregateZero>(FilterClause)) {
2258 // Not an empty filter - it contains at least one null typeinfo.
2259 assert(NumTypeInfos > 0 && "Should have handled empty filter already!");
2260 Constant *TypeInfo =
2261 Constant::getNullValue(FilterType->getElementType());
2262 // If this typeinfo is a catch-all then the filter can never match.
2263 if (isCatchAll(Personality, TypeInfo)) {
2264 // Throw the filter away.
2265 MakeNewInstruction = true;
2269 // There is no point in having multiple copies of this typeinfo, so
2270 // discard all but the first copy if there is more than one.
2271 NewFilterElts.push_back(TypeInfo);
2272 if (NumTypeInfos > 1)
2273 MakeNewFilter = true;
2275 ConstantArray *Filter = cast<ConstantArray>(FilterClause);
2276 SmallPtrSet<Value *, 16> SeenInFilter; // For uniquing the elements.
2277 NewFilterElts.reserve(NumTypeInfos);
2279 // Remove any filter elements that were already caught or that already
2280 // occurred in the filter. While there, see if any of the elements are
2281 // catch-alls. If so, the filter can be discarded.
2282 bool SawCatchAll = false;
2283 for (unsigned j = 0; j != NumTypeInfos; ++j) {
2284 Constant *Elt = Filter->getOperand(j);
2285 Constant *TypeInfo = Elt->stripPointerCasts();
2286 if (isCatchAll(Personality, TypeInfo)) {
2287 // This element is a catch-all. Bail out, noting this fact.
2291 if (AlreadyCaught.count(TypeInfo))
2292 // Already caught by an earlier clause, so having it in the filter
2295 // There is no point in having multiple copies of the same typeinfo in
2296 // a filter, so only add it if we didn't already.
2297 if (SeenInFilter.insert(TypeInfo))
2298 NewFilterElts.push_back(cast<Constant>(Elt));
2300 // A filter containing a catch-all cannot match anything by definition.
2302 // Throw the filter away.
2303 MakeNewInstruction = true;
2307 // If we dropped something from the filter, make a new one.
2308 if (NewFilterElts.size() < NumTypeInfos)
2309 MakeNewFilter = true;
2311 if (MakeNewFilter) {
2312 FilterType = ArrayType::get(FilterType->getElementType(),
2313 NewFilterElts.size());
2314 FilterClause = ConstantArray::get(FilterType, NewFilterElts);
2315 MakeNewInstruction = true;
2318 NewClauses.push_back(FilterClause);
2320 // If the new filter is empty then it will catch everything so there is
2321 // no point in keeping any following clauses or marking the landingpad
2322 // as having a cleanup. The case of the original filter being empty was
2323 // already handled above.
2324 if (MakeNewFilter && !NewFilterElts.size()) {
2325 assert(MakeNewInstruction && "New filter but not a new instruction!");
2326 CleanupFlag = false;
2332 // If several filters occur in a row then reorder them so that the shortest
2333 // filters come first (those with the smallest number of elements). This is
2334 // advantageous because shorter filters are more likely to match, speeding up
2335 // unwinding, but mostly because it increases the effectiveness of the other
2336 // filter optimizations below.
2337 for (unsigned i = 0, e = NewClauses.size(); i + 1 < e; ) {
2339 // Find the maximal 'j' s.t. the range [i, j) consists entirely of filters.
2340 for (j = i; j != e; ++j)
2341 if (!isa<ArrayType>(NewClauses[j]->getType()))
2344 // Check whether the filters are already sorted by length. We need to know
2345 // if sorting them is actually going to do anything so that we only make a
2346 // new landingpad instruction if it does.
2347 for (unsigned k = i; k + 1 < j; ++k)
2348 if (shorter_filter(NewClauses[k+1], NewClauses[k])) {
2349 // Not sorted, so sort the filters now. Doing an unstable sort would be
2350 // correct too but reordering filters pointlessly might confuse users.
2351 std::stable_sort(NewClauses.begin() + i, NewClauses.begin() + j,
2353 MakeNewInstruction = true;
2357 // Look for the next batch of filters.
2361 // If typeinfos matched if and only if equal, then the elements of a filter L
2362 // that occurs later than a filter F could be replaced by the intersection of
2363 // the elements of F and L. In reality two typeinfos can match without being
2364 // equal (for example if one represents a C++ class, and the other some class
2365 // derived from it) so it would be wrong to perform this transform in general.
2366 // However the transform is correct and useful if F is a subset of L. In that
2367 // case L can be replaced by F, and thus removed altogether since repeating a
2368 // filter is pointless. So here we look at all pairs of filters F and L where
2369 // L follows F in the list of clauses, and remove L if every element of F is
2370 // an element of L. This can occur when inlining C++ functions with exception
2372 for (unsigned i = 0; i + 1 < NewClauses.size(); ++i) {
2373 // Examine each filter in turn.
2374 Value *Filter = NewClauses[i];
2375 ArrayType *FTy = dyn_cast<ArrayType>(Filter->getType());
2377 // Not a filter - skip it.
2379 unsigned FElts = FTy->getNumElements();
2380 // Examine each filter following this one. Doing this backwards means that
2381 // we don't have to worry about filters disappearing under us when removed.
2382 for (unsigned j = NewClauses.size() - 1; j != i; --j) {
2383 Value *LFilter = NewClauses[j];
2384 ArrayType *LTy = dyn_cast<ArrayType>(LFilter->getType());
2386 // Not a filter - skip it.
2388 // If Filter is a subset of LFilter, i.e. every element of Filter is also
2389 // an element of LFilter, then discard LFilter.
2390 SmallVectorImpl<Constant *>::iterator J = NewClauses.begin() + j;
2391 // If Filter is empty then it is a subset of LFilter.
2394 NewClauses.erase(J);
2395 MakeNewInstruction = true;
2396 // Move on to the next filter.
2399 unsigned LElts = LTy->getNumElements();
2400 // If Filter is longer than LFilter then it cannot be a subset of it.
2402 // Move on to the next filter.
2404 // At this point we know that LFilter has at least one element.
2405 if (isa<ConstantAggregateZero>(LFilter)) { // LFilter only contains zeros.
2406 // Filter is a subset of LFilter iff Filter contains only zeros (as we
2407 // already know that Filter is not longer than LFilter).
2408 if (isa<ConstantAggregateZero>(Filter)) {
2409 assert(FElts <= LElts && "Should have handled this case earlier!");
2411 NewClauses.erase(J);
2412 MakeNewInstruction = true;
2414 // Move on to the next filter.
2417 ConstantArray *LArray = cast<ConstantArray>(LFilter);
2418 if (isa<ConstantAggregateZero>(Filter)) { // Filter only contains zeros.
2419 // Since Filter is non-empty and contains only zeros, it is a subset of
2420 // LFilter iff LFilter contains a zero.
2421 assert(FElts > 0 && "Should have eliminated the empty filter earlier!");
2422 for (unsigned l = 0; l != LElts; ++l)
2423 if (LArray->getOperand(l)->isNullValue()) {
2424 // LFilter contains a zero - discard it.
2425 NewClauses.erase(J);
2426 MakeNewInstruction = true;
2429 // Move on to the next filter.
2432 // At this point we know that both filters are ConstantArrays. Loop over
2433 // operands to see whether every element of Filter is also an element of
2434 // LFilter. Since filters tend to be short this is probably faster than
2435 // using a method that scales nicely.
2436 ConstantArray *FArray = cast<ConstantArray>(Filter);
2437 bool AllFound = true;
2438 for (unsigned f = 0; f != FElts; ++f) {
2439 Value *FTypeInfo = FArray->getOperand(f)->stripPointerCasts();
2441 for (unsigned l = 0; l != LElts; ++l) {
2442 Value *LTypeInfo = LArray->getOperand(l)->stripPointerCasts();
2443 if (LTypeInfo == FTypeInfo) {
2453 NewClauses.erase(J);
2454 MakeNewInstruction = true;
2456 // Move on to the next filter.
2460 // If we changed any of the clauses, replace the old landingpad instruction
2462 if (MakeNewInstruction) {
2463 LandingPadInst *NLI = LandingPadInst::Create(LI.getType(),
2464 LI.getPersonalityFn(),
2466 for (unsigned i = 0, e = NewClauses.size(); i != e; ++i)
2467 NLI->addClause(NewClauses[i]);
2468 // A landing pad with no clauses must have the cleanup flag set. It is
2469 // theoretically possible, though highly unlikely, that we eliminated all
2470 // clauses. If so, force the cleanup flag to true.
2471 if (NewClauses.empty())
2473 NLI->setCleanup(CleanupFlag);
2477 // Even if none of the clauses changed, we may nonetheless have understood
2478 // that the cleanup flag is pointless. Clear it if so.
2479 if (LI.isCleanup() != CleanupFlag) {
2480 assert(!CleanupFlag && "Adding a cleanup, not removing one?!");
2481 LI.setCleanup(CleanupFlag);
2491 /// TryToSinkInstruction - Try to move the specified instruction from its
2492 /// current block into the beginning of DestBlock, which can only happen if it's
2493 /// safe to move the instruction past all of the instructions between it and the
2494 /// end of its block.
2495 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
2496 assert(I->hasOneUse() && "Invariants didn't hold!");
2498 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
2499 if (isa<PHINode>(I) || isa<LandingPadInst>(I) || I->mayHaveSideEffects() ||
2500 isa<TerminatorInst>(I))
2503 // Do not sink alloca instructions out of the entry block.
2504 if (isa<AllocaInst>(I) && I->getParent() ==
2505 &DestBlock->getParent()->getEntryBlock())
2508 // We can only sink load instructions if there is nothing between the load and
2509 // the end of block that could change the value.
2510 if (I->mayReadFromMemory()) {
2511 for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
2513 if (Scan->mayWriteToMemory())
2517 BasicBlock::iterator InsertPos = DestBlock->getFirstInsertionPt();
2518 I->moveBefore(InsertPos);
2524 /// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
2525 /// all reachable code to the worklist.
2527 /// This has a couple of tricks to make the code faster and more powerful. In
2528 /// particular, we constant fold and DCE instructions as we go, to avoid adding
2529 /// them to the worklist (this significantly speeds up instcombine on code where
2530 /// many instructions are dead or constant). Additionally, if we find a branch
2531 /// whose condition is a known constant, we only visit the reachable successors.
2533 static bool AddReachableCodeToWorklist(BasicBlock *BB,
2534 SmallPtrSet<BasicBlock*, 64> &Visited,
2536 const DataLayout *DL,
2537 const TargetLibraryInfo *TLI) {
2538 bool MadeIRChange = false;
2539 SmallVector<BasicBlock*, 256> Worklist;
2540 Worklist.push_back(BB);
2542 SmallVector<Instruction*, 128> InstrsForInstCombineWorklist;
2543 DenseMap<ConstantExpr*, Constant*> FoldedConstants;
2546 BB = Worklist.pop_back_val();
2548 // We have now visited this block! If we've already been here, ignore it.
2549 if (!Visited.insert(BB)) continue;
2551 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
2552 Instruction *Inst = BBI++;
2554 // DCE instruction if trivially dead.
2555 if (isInstructionTriviallyDead(Inst, TLI)) {
2557 DEBUG(dbgs() << "IC: DCE: " << *Inst << '\n');
2558 Inst->eraseFromParent();
2562 // ConstantProp instruction if trivially constant.
2563 if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
2564 if (Constant *C = ConstantFoldInstruction(Inst, DL, TLI)) {
2565 DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: "
2567 Inst->replaceAllUsesWith(C);
2569 Inst->eraseFromParent();
2574 // See if we can constant fold its operands.
2575 for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end();
2577 ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
2578 if (CE == nullptr) continue;
2580 Constant*& FoldRes = FoldedConstants[CE];
2582 FoldRes = ConstantFoldConstantExpression(CE, DL, TLI);
2586 if (FoldRes != CE) {
2588 MadeIRChange = true;
2593 InstrsForInstCombineWorklist.push_back(Inst);
2596 // Recursively visit successors. If this is a branch or switch on a
2597 // constant, only visit the reachable successor.
2598 TerminatorInst *TI = BB->getTerminator();
2599 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
2600 if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
2601 bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
2602 BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
2603 Worklist.push_back(ReachableBB);
2606 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
2607 if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
2608 // See if this is an explicit destination.
2609 for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
2611 if (i.getCaseValue() == Cond) {
2612 BasicBlock *ReachableBB = i.getCaseSuccessor();
2613 Worklist.push_back(ReachableBB);
2617 // Otherwise it is the default destination.
2618 Worklist.push_back(SI->getDefaultDest());
2623 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
2624 Worklist.push_back(TI->getSuccessor(i));
2625 } while (!Worklist.empty());
2627 // Once we've found all of the instructions to add to instcombine's worklist,
2628 // add them in reverse order. This way instcombine will visit from the top
2629 // of the function down. This jives well with the way that it adds all uses
2630 // of instructions to the worklist after doing a transformation, thus avoiding
2631 // some N^2 behavior in pathological cases.
2632 IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
2633 InstrsForInstCombineWorklist.size());
2635 return MadeIRChange;
2638 bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
2639 MadeIRChange = false;
2641 DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
2642 << F.getName() << "\n");
2645 // Do a depth-first traversal of the function, populate the worklist with
2646 // the reachable instructions. Ignore blocks that are not reachable. Keep
2647 // track of which blocks we visit.
2648 SmallPtrSet<BasicBlock*, 64> Visited;
2649 MadeIRChange |= AddReachableCodeToWorklist(F.begin(), Visited, *this, DL,
2652 // Do a quick scan over the function. If we find any blocks that are
2653 // unreachable, remove any instructions inside of them. This prevents
2654 // the instcombine code from having to deal with some bad special cases.
2655 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
2656 if (Visited.count(BB)) continue;
2658 // Delete the instructions backwards, as it has a reduced likelihood of
2659 // having to update as many def-use and use-def chains.
2660 Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
2661 while (EndInst != BB->begin()) {
2662 // Delete the next to last instruction.
2663 BasicBlock::iterator I = EndInst;
2664 Instruction *Inst = --I;
2665 if (!Inst->use_empty())
2666 Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
2667 if (isa<LandingPadInst>(Inst)) {
2671 if (!isa<DbgInfoIntrinsic>(Inst)) {
2673 MadeIRChange = true;
2675 Inst->eraseFromParent();
2680 while (!Worklist.isEmpty()) {
2681 Instruction *I = Worklist.RemoveOne();
2682 if (I == nullptr) continue; // skip null values.
2684 // Check to see if we can DCE the instruction.
2685 if (isInstructionTriviallyDead(I, TLI)) {
2686 DEBUG(dbgs() << "IC: DCE: " << *I << '\n');
2687 EraseInstFromFunction(*I);
2689 MadeIRChange = true;
2693 // Instruction isn't dead, see if we can constant propagate it.
2694 if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
2695 if (Constant *C = ConstantFoldInstruction(I, DL, TLI)) {
2696 DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
2698 // Add operands to the worklist.
2699 ReplaceInstUsesWith(*I, C);
2701 EraseInstFromFunction(*I);
2702 MadeIRChange = true;
2706 // See if we can trivially sink this instruction to a successor basic block.
2707 if (I->hasOneUse()) {
2708 BasicBlock *BB = I->getParent();
2709 Instruction *UserInst = cast<Instruction>(*I->user_begin());
2710 BasicBlock *UserParent;
2712 // Get the block the use occurs in.
2713 if (PHINode *PN = dyn_cast<PHINode>(UserInst))
2714 UserParent = PN->getIncomingBlock(*I->use_begin());
2716 UserParent = UserInst->getParent();
2718 if (UserParent != BB) {
2719 bool UserIsSuccessor = false;
2720 // See if the user is one of our successors.
2721 for (BasicBlock *Succ : successors(BB))
2722 if (Succ == UserParent) {
2723 UserIsSuccessor = true;
2727 // If the user is one of our immediate successors, and if that successor
2728 // only has us as a predecessors (we'd have to split the critical edge
2729 // otherwise), we can keep going.
2730 if (UserIsSuccessor && UserParent->getSinglePredecessor()) {
2731 // Okay, the CFG is simple enough, try to sink this instruction.
2732 if (TryToSinkInstruction(I, UserParent)) {
2733 MadeIRChange = true;
2734 // We'll add uses of the sunk instruction below, but since sinking
2735 // can expose opportunities for it's *operands* add them to the
2737 for (Use &U : I->operands())
2738 if (Instruction *OpI = dyn_cast<Instruction>(U.get()))
2745 // Now that we have an instruction, try combining it to simplify it.
2746 Builder->SetInsertPoint(I->getParent(), I);
2747 Builder->SetCurrentDebugLocation(I->getDebugLoc());
2752 DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
2753 DEBUG(dbgs() << "IC: Visiting: " << OrigI << '\n');
2755 if (Instruction *Result = visit(*I)) {
2757 // Should we replace the old instruction with a new one?
2759 DEBUG(dbgs() << "IC: Old = " << *I << '\n'
2760 << " New = " << *Result << '\n');
2762 if (!I->getDebugLoc().isUnknown())
2763 Result->setDebugLoc(I->getDebugLoc());
2764 // Everything uses the new instruction now.
2765 I->replaceAllUsesWith(Result);
2767 // Move the name to the new instruction first.
2768 Result->takeName(I);
2770 // Push the new instruction and any users onto the worklist.
2771 Worklist.Add(Result);
2772 Worklist.AddUsersToWorkList(*Result);
2774 // Insert the new instruction into the basic block...
2775 BasicBlock *InstParent = I->getParent();
2776 BasicBlock::iterator InsertPos = I;
2778 // If we replace a PHI with something that isn't a PHI, fix up the
2780 if (!isa<PHINode>(Result) && isa<PHINode>(InsertPos))
2781 InsertPos = InstParent->getFirstInsertionPt();
2783 InstParent->getInstList().insert(InsertPos, Result);
2785 EraseInstFromFunction(*I);
2788 DEBUG(dbgs() << "IC: Mod = " << OrigI << '\n'
2789 << " New = " << *I << '\n');
2792 // If the instruction was modified, it's possible that it is now dead.
2793 // if so, remove it.
2794 if (isInstructionTriviallyDead(I, TLI)) {
2795 EraseInstFromFunction(*I);
2798 Worklist.AddUsersToWorkList(*I);
2801 MadeIRChange = true;
2806 return MadeIRChange;
2810 class InstCombinerLibCallSimplifier : public LibCallSimplifier {
2813 InstCombinerLibCallSimplifier(const DataLayout *DL,
2814 const TargetLibraryInfo *TLI,
2816 : LibCallSimplifier(DL, TLI, UnsafeFPShrink) {
2820 /// replaceAllUsesWith - override so that instruction replacement
2821 /// can be defined in terms of the instruction combiner framework.
2822 void replaceAllUsesWith(Instruction *I, Value *With) const override {
2823 IC->ReplaceInstUsesWith(*I, With);
2828 bool InstCombiner::runOnFunction(Function &F) {
2829 if (skipOptnoneFunction(F))
2832 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
2833 DL = DLP ? &DLP->getDataLayout() : nullptr;
2834 TLI = &getAnalysis<TargetLibraryInfo>();
2836 MinimizeSize = F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
2837 Attribute::MinSize);
2839 /// Builder - This is an IRBuilder that automatically inserts new
2840 /// instructions into the worklist when they are created.
2841 IRBuilder<true, TargetFolder, InstCombineIRInserter>
2842 TheBuilder(F.getContext(), TargetFolder(DL),
2843 InstCombineIRInserter(Worklist));
2844 Builder = &TheBuilder;
2846 InstCombinerLibCallSimplifier TheSimplifier(DL, TLI, this);
2847 Simplifier = &TheSimplifier;
2849 bool EverMadeChange = false;
2851 // Lower dbg.declare intrinsics otherwise their value may be clobbered
2853 EverMadeChange = LowerDbgDeclare(F);
2855 // Iterate while there is work to do.
2856 unsigned Iteration = 0;
2857 while (DoOneIteration(F, Iteration++))
2858 EverMadeChange = true;
2861 return EverMadeChange;
2864 FunctionPass *llvm::createInstructionCombiningPass() {
2865 return new InstCombiner();