1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
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 // This file implements routines for folding instructions into simpler forms
11 // that do not require creating new instructions. This does constant folding
12 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
13 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
14 // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
15 // simplified: This is usually true and assuming it simplifies the logic (if
16 // they have not been simplified then results are correct but maybe suboptimal).
18 //===----------------------------------------------------------------------===//
20 #include "llvm/Analysis/InstructionSimplify.h"
21 #include "llvm/ADT/SetVector.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/Analysis/AliasAnalysis.h"
24 #include "llvm/Analysis/ConstantFolding.h"
25 #include "llvm/Analysis/MemoryBuiltins.h"
26 #include "llvm/Analysis/ValueTracking.h"
27 #include "llvm/IR/ConstantRange.h"
28 #include "llvm/IR/DataLayout.h"
29 #include "llvm/IR/Dominators.h"
30 #include "llvm/IR/GetElementPtrTypeIterator.h"
31 #include "llvm/IR/GlobalAlias.h"
32 #include "llvm/IR/Operator.h"
33 #include "llvm/IR/PatternMatch.h"
34 #include "llvm/IR/ValueHandle.h"
37 using namespace llvm::PatternMatch;
39 #define DEBUG_TYPE "instsimplify"
41 enum { RecursionLimit = 3 };
43 STATISTIC(NumExpand, "Number of expansions");
44 STATISTIC(NumReassoc, "Number of reassociations");
49 const TargetLibraryInfo *TLI;
50 const DominatorTree *DT;
52 const Instruction *CxtI;
54 Query(const DataLayout &DL, const TargetLibraryInfo *tli,
55 const DominatorTree *dt, AssumptionCache *ac = nullptr,
56 const Instruction *cxti = nullptr)
57 : DL(DL), TLI(tli), DT(dt), AC(ac), CxtI(cxti) {}
59 } // end anonymous namespace
61 static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
62 static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
64 static Value *SimplifyFPBinOp(unsigned, Value *, Value *, const FastMathFlags &,
65 const Query &, unsigned);
66 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
68 static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
69 static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
70 static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned);
72 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
73 /// a vector with every element false, as appropriate for the type.
74 static Constant *getFalse(Type *Ty) {
75 assert(Ty->getScalarType()->isIntegerTy(1) &&
76 "Expected i1 type or a vector of i1!");
77 return Constant::getNullValue(Ty);
80 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
81 /// a vector with every element true, as appropriate for the type.
82 static Constant *getTrue(Type *Ty) {
83 assert(Ty->getScalarType()->isIntegerTy(1) &&
84 "Expected i1 type or a vector of i1!");
85 return Constant::getAllOnesValue(Ty);
88 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
89 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
91 CmpInst *Cmp = dyn_cast<CmpInst>(V);
94 CmpInst::Predicate CPred = Cmp->getPredicate();
95 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
96 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
98 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
102 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
103 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
104 Instruction *I = dyn_cast<Instruction>(V);
106 // Arguments and constants dominate all instructions.
109 // If we are processing instructions (and/or basic blocks) that have not been
110 // fully added to a function, the parent nodes may still be null. Simply
111 // return the conservative answer in these cases.
112 if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
115 // If we have a DominatorTree then do a precise test.
117 if (!DT->isReachableFromEntry(P->getParent()))
119 if (!DT->isReachableFromEntry(I->getParent()))
121 return DT->dominates(I, P);
124 // Otherwise, if the instruction is in the entry block, and is not an invoke,
125 // then it obviously dominates all phi nodes.
126 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
133 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
134 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
135 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
136 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
137 /// Returns the simplified value, or null if no simplification was performed.
138 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
139 unsigned OpcToExpand, const Query &Q,
140 unsigned MaxRecurse) {
141 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
142 // Recursion is always used, so bail out at once if we already hit the limit.
146 // Check whether the expression has the form "(A op' B) op C".
147 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
148 if (Op0->getOpcode() == OpcodeToExpand) {
149 // It does! Try turning it into "(A op C) op' (B op C)".
150 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
151 // Do "A op C" and "B op C" both simplify?
152 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
153 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
154 // They do! Return "L op' R" if it simplifies or is already available.
155 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
156 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
157 && L == B && R == A)) {
161 // Otherwise return "L op' R" if it simplifies.
162 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
169 // Check whether the expression has the form "A op (B op' C)".
170 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
171 if (Op1->getOpcode() == OpcodeToExpand) {
172 // It does! Try turning it into "(A op B) op' (A op C)".
173 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
174 // Do "A op B" and "A op C" both simplify?
175 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
176 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
177 // They do! Return "L op' R" if it simplifies or is already available.
178 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
179 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
180 && L == C && R == B)) {
184 // Otherwise return "L op' R" if it simplifies.
185 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
195 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
196 /// operations. Returns the simpler value, or null if none was found.
197 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
198 const Query &Q, unsigned MaxRecurse) {
199 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
200 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
202 // Recursion is always used, so bail out at once if we already hit the limit.
206 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
207 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
209 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
210 if (Op0 && Op0->getOpcode() == Opcode) {
211 Value *A = Op0->getOperand(0);
212 Value *B = Op0->getOperand(1);
215 // Does "B op C" simplify?
216 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
217 // It does! Return "A op V" if it simplifies or is already available.
218 // If V equals B then "A op V" is just the LHS.
219 if (V == B) return LHS;
220 // Otherwise return "A op V" if it simplifies.
221 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
228 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
229 if (Op1 && Op1->getOpcode() == Opcode) {
231 Value *B = Op1->getOperand(0);
232 Value *C = Op1->getOperand(1);
234 // Does "A op B" simplify?
235 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
236 // It does! Return "V op C" if it simplifies or is already available.
237 // If V equals B then "V op C" is just the RHS.
238 if (V == B) return RHS;
239 // Otherwise return "V op C" if it simplifies.
240 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
247 // The remaining transforms require commutativity as well as associativity.
248 if (!Instruction::isCommutative(Opcode))
251 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
252 if (Op0 && Op0->getOpcode() == Opcode) {
253 Value *A = Op0->getOperand(0);
254 Value *B = Op0->getOperand(1);
257 // Does "C op A" simplify?
258 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
259 // It does! Return "V op B" if it simplifies or is already available.
260 // If V equals A then "V op B" is just the LHS.
261 if (V == A) return LHS;
262 // Otherwise return "V op B" if it simplifies.
263 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
270 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
271 if (Op1 && Op1->getOpcode() == Opcode) {
273 Value *B = Op1->getOperand(0);
274 Value *C = Op1->getOperand(1);
276 // Does "C op A" simplify?
277 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
278 // It does! Return "B op V" if it simplifies or is already available.
279 // If V equals C then "B op V" is just the RHS.
280 if (V == C) return RHS;
281 // Otherwise return "B op V" if it simplifies.
282 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
292 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
293 /// instruction as an operand, try to simplify the binop by seeing whether
294 /// evaluating it on both branches of the select results in the same value.
295 /// Returns the common value if so, otherwise returns null.
296 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
297 const Query &Q, unsigned MaxRecurse) {
298 // Recursion is always used, so bail out at once if we already hit the limit.
303 if (isa<SelectInst>(LHS)) {
304 SI = cast<SelectInst>(LHS);
306 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
307 SI = cast<SelectInst>(RHS);
310 // Evaluate the BinOp on the true and false branches of the select.
314 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
315 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
317 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
318 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
321 // If they simplified to the same value, then return the common value.
322 // If they both failed to simplify then return null.
326 // If one branch simplified to undef, return the other one.
327 if (TV && isa<UndefValue>(TV))
329 if (FV && isa<UndefValue>(FV))
332 // If applying the operation did not change the true and false select values,
333 // then the result of the binop is the select itself.
334 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
337 // If one branch simplified and the other did not, and the simplified
338 // value is equal to the unsimplified one, return the simplified value.
339 // For example, select (cond, X, X & Z) & Z -> X & Z.
340 if ((FV && !TV) || (TV && !FV)) {
341 // Check that the simplified value has the form "X op Y" where "op" is the
342 // same as the original operation.
343 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
344 if (Simplified && Simplified->getOpcode() == Opcode) {
345 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
346 // We already know that "op" is the same as for the simplified value. See
347 // if the operands match too. If so, return the simplified value.
348 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
349 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
350 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
351 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
352 Simplified->getOperand(1) == UnsimplifiedRHS)
354 if (Simplified->isCommutative() &&
355 Simplified->getOperand(1) == UnsimplifiedLHS &&
356 Simplified->getOperand(0) == UnsimplifiedRHS)
364 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
365 /// try to simplify the comparison by seeing whether both branches of the select
366 /// result in the same value. Returns the common value if so, otherwise returns
368 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
369 Value *RHS, const Query &Q,
370 unsigned MaxRecurse) {
371 // Recursion is always used, so bail out at once if we already hit the limit.
375 // Make sure the select is on the LHS.
376 if (!isa<SelectInst>(LHS)) {
378 Pred = CmpInst::getSwappedPredicate(Pred);
380 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
381 SelectInst *SI = cast<SelectInst>(LHS);
382 Value *Cond = SI->getCondition();
383 Value *TV = SI->getTrueValue();
384 Value *FV = SI->getFalseValue();
386 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
387 // Does "cmp TV, RHS" simplify?
388 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
390 // It not only simplified, it simplified to the select condition. Replace
392 TCmp = getTrue(Cond->getType());
394 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
395 // condition then we can replace it with 'true'. Otherwise give up.
396 if (!isSameCompare(Cond, Pred, TV, RHS))
398 TCmp = getTrue(Cond->getType());
401 // Does "cmp FV, RHS" simplify?
402 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
404 // It not only simplified, it simplified to the select condition. Replace
406 FCmp = getFalse(Cond->getType());
408 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
409 // condition then we can replace it with 'false'. Otherwise give up.
410 if (!isSameCompare(Cond, Pred, FV, RHS))
412 FCmp = getFalse(Cond->getType());
415 // If both sides simplified to the same value, then use it as the result of
416 // the original comparison.
420 // The remaining cases only make sense if the select condition has the same
421 // type as the result of the comparison, so bail out if this is not so.
422 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
424 // If the false value simplified to false, then the result of the compare
425 // is equal to "Cond && TCmp". This also catches the case when the false
426 // value simplified to false and the true value to true, returning "Cond".
427 if (match(FCmp, m_Zero()))
428 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
430 // If the true value simplified to true, then the result of the compare
431 // is equal to "Cond || FCmp".
432 if (match(TCmp, m_One()))
433 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
435 // Finally, if the false value simplified to true and the true value to
436 // false, then the result of the compare is equal to "!Cond".
437 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
439 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
446 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
447 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
448 /// it on the incoming phi values yields the same result for every value. If so
449 /// returns the common value, otherwise returns null.
450 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
451 const Query &Q, unsigned MaxRecurse) {
452 // Recursion is always used, so bail out at once if we already hit the limit.
457 if (isa<PHINode>(LHS)) {
458 PI = cast<PHINode>(LHS);
459 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
460 if (!ValueDominatesPHI(RHS, PI, Q.DT))
463 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
464 PI = cast<PHINode>(RHS);
465 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
466 if (!ValueDominatesPHI(LHS, PI, Q.DT))
470 // Evaluate the BinOp on the incoming phi values.
471 Value *CommonValue = nullptr;
472 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
473 Value *Incoming = PI->getIncomingValue(i);
474 // If the incoming value is the phi node itself, it can safely be skipped.
475 if (Incoming == PI) continue;
476 Value *V = PI == LHS ?
477 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
478 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
479 // If the operation failed to simplify, or simplified to a different value
480 // to previously, then give up.
481 if (!V || (CommonValue && V != CommonValue))
489 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
490 /// try to simplify the comparison by seeing whether comparing with all of the
491 /// incoming phi values yields the same result every time. If so returns the
492 /// common result, otherwise returns null.
493 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
494 const Query &Q, unsigned MaxRecurse) {
495 // Recursion is always used, so bail out at once if we already hit the limit.
499 // Make sure the phi is on the LHS.
500 if (!isa<PHINode>(LHS)) {
502 Pred = CmpInst::getSwappedPredicate(Pred);
504 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
505 PHINode *PI = cast<PHINode>(LHS);
507 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
508 if (!ValueDominatesPHI(RHS, PI, Q.DT))
511 // Evaluate the BinOp on the incoming phi values.
512 Value *CommonValue = nullptr;
513 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
514 Value *Incoming = PI->getIncomingValue(i);
515 // If the incoming value is the phi node itself, it can safely be skipped.
516 if (Incoming == PI) continue;
517 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
518 // If the operation failed to simplify, or simplified to a different value
519 // to previously, then give up.
520 if (!V || (CommonValue && V != CommonValue))
528 /// SimplifyAddInst - Given operands for an Add, see if we can
529 /// fold the result. If not, this returns null.
530 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
531 const Query &Q, unsigned MaxRecurse) {
532 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
533 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
534 Constant *Ops[] = { CLHS, CRHS };
535 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops,
539 // Canonicalize the constant to the RHS.
543 // X + undef -> undef
544 if (match(Op1, m_Undef()))
548 if (match(Op1, m_Zero()))
555 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
556 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
559 // X + ~X -> -1 since ~X = -X-1
560 if (match(Op0, m_Not(m_Specific(Op1))) ||
561 match(Op1, m_Not(m_Specific(Op0))))
562 return Constant::getAllOnesValue(Op0->getType());
565 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
566 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
569 // Try some generic simplifications for associative operations.
570 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
574 // Threading Add over selects and phi nodes is pointless, so don't bother.
575 // Threading over the select in "A + select(cond, B, C)" means evaluating
576 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
577 // only if B and C are equal. If B and C are equal then (since we assume
578 // that operands have already been simplified) "select(cond, B, C)" should
579 // have been simplified to the common value of B and C already. Analysing
580 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
581 // for threading over phi nodes.
586 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
587 const DataLayout &DL, const TargetLibraryInfo *TLI,
588 const DominatorTree *DT, AssumptionCache *AC,
589 const Instruction *CxtI) {
590 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
594 /// \brief Compute the base pointer and cumulative constant offsets for V.
596 /// This strips all constant offsets off of V, leaving it the base pointer, and
597 /// accumulates the total constant offset applied in the returned constant. It
598 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
599 /// no constant offsets applied.
601 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
602 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
604 static Constant *stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V,
605 bool AllowNonInbounds = false) {
606 assert(V->getType()->getScalarType()->isPointerTy());
608 Type *IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType();
609 APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
611 // Even though we don't look through PHI nodes, we could be called on an
612 // instruction in an unreachable block, which may be on a cycle.
613 SmallPtrSet<Value *, 4> Visited;
616 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
617 if ((!AllowNonInbounds && !GEP->isInBounds()) ||
618 !GEP->accumulateConstantOffset(DL, Offset))
620 V = GEP->getPointerOperand();
621 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
622 V = cast<Operator>(V)->getOperand(0);
623 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
624 if (GA->mayBeOverridden())
626 V = GA->getAliasee();
630 assert(V->getType()->getScalarType()->isPointerTy() &&
631 "Unexpected operand type!");
632 } while (Visited.insert(V).second);
634 Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
635 if (V->getType()->isVectorTy())
636 return ConstantVector::getSplat(V->getType()->getVectorNumElements(),
641 /// \brief Compute the constant difference between two pointer values.
642 /// If the difference is not a constant, returns zero.
643 static Constant *computePointerDifference(const DataLayout &DL, Value *LHS,
645 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
646 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
648 // If LHS and RHS are not related via constant offsets to the same base
649 // value, there is nothing we can do here.
653 // Otherwise, the difference of LHS - RHS can be computed as:
655 // = (LHSOffset + Base) - (RHSOffset + Base)
656 // = LHSOffset - RHSOffset
657 return ConstantExpr::getSub(LHSOffset, RHSOffset);
660 /// SimplifySubInst - Given operands for a Sub, see if we can
661 /// fold the result. If not, this returns null.
662 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
663 const Query &Q, unsigned MaxRecurse) {
664 if (Constant *CLHS = dyn_cast<Constant>(Op0))
665 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
666 Constant *Ops[] = { CLHS, CRHS };
667 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
671 // X - undef -> undef
672 // undef - X -> undef
673 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
674 return UndefValue::get(Op0->getType());
677 if (match(Op1, m_Zero()))
682 return Constant::getNullValue(Op0->getType());
684 // 0 - X -> 0 if the sub is NUW.
685 if (isNUW && match(Op0, m_Zero()))
688 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
689 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
690 Value *X = nullptr, *Y = nullptr, *Z = Op1;
691 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
692 // See if "V === Y - Z" simplifies.
693 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
694 // It does! Now see if "X + V" simplifies.
695 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
696 // It does, we successfully reassociated!
700 // See if "V === X - Z" simplifies.
701 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
702 // It does! Now see if "Y + V" simplifies.
703 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
704 // It does, we successfully reassociated!
710 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
711 // For example, X - (X + 1) -> -1
713 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
714 // See if "V === X - Y" simplifies.
715 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
716 // It does! Now see if "V - Z" simplifies.
717 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
718 // It does, we successfully reassociated!
722 // See if "V === X - Z" simplifies.
723 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
724 // It does! Now see if "V - Y" simplifies.
725 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
726 // It does, we successfully reassociated!
732 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
733 // For example, X - (X - Y) -> Y.
735 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
736 // See if "V === Z - X" simplifies.
737 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
738 // It does! Now see if "V + Y" simplifies.
739 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
740 // It does, we successfully reassociated!
745 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
746 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
747 match(Op1, m_Trunc(m_Value(Y))))
748 if (X->getType() == Y->getType())
749 // See if "V === X - Y" simplifies.
750 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
751 // It does! Now see if "trunc V" simplifies.
752 if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1))
753 // It does, return the simplified "trunc V".
756 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
757 if (match(Op0, m_PtrToInt(m_Value(X))) &&
758 match(Op1, m_PtrToInt(m_Value(Y))))
759 if (Constant *Result = computePointerDifference(Q.DL, X, Y))
760 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
763 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
764 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
767 // Threading Sub over selects and phi nodes is pointless, so don't bother.
768 // Threading over the select in "A - select(cond, B, C)" means evaluating
769 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
770 // only if B and C are equal. If B and C are equal then (since we assume
771 // that operands have already been simplified) "select(cond, B, C)" should
772 // have been simplified to the common value of B and C already. Analysing
773 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
774 // for threading over phi nodes.
779 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
780 const DataLayout &DL, const TargetLibraryInfo *TLI,
781 const DominatorTree *DT, AssumptionCache *AC,
782 const Instruction *CxtI) {
783 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
787 /// Given operands for an FAdd, see if we can fold the result. If not, this
789 static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
790 const Query &Q, unsigned MaxRecurse) {
791 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
792 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
793 Constant *Ops[] = { CLHS, CRHS };
794 return ConstantFoldInstOperands(Instruction::FAdd, CLHS->getType(),
798 // Canonicalize the constant to the RHS.
803 if (match(Op1, m_NegZero()))
806 // fadd X, 0 ==> X, when we know X is not -0
807 if (match(Op1, m_Zero()) &&
808 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0)))
811 // fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
812 // where nnan and ninf have to occur at least once somewhere in this
814 Value *SubOp = nullptr;
815 if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0))))
817 else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1))))
820 Instruction *FSub = cast<Instruction>(SubOp);
821 if ((FMF.noNaNs() || FSub->hasNoNaNs()) &&
822 (FMF.noInfs() || FSub->hasNoInfs()))
823 return Constant::getNullValue(Op0->getType());
829 /// Given operands for an FSub, see if we can fold the result. If not, this
831 static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
832 const Query &Q, unsigned MaxRecurse) {
833 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
834 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
835 Constant *Ops[] = { CLHS, CRHS };
836 return ConstantFoldInstOperands(Instruction::FSub, CLHS->getType(),
842 if (match(Op1, m_Zero()))
845 // fsub X, -0 ==> X, when we know X is not -0
846 if (match(Op1, m_NegZero()) &&
847 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0)))
850 // fsub 0, (fsub -0.0, X) ==> X
852 if (match(Op0, m_AnyZero())) {
853 if (match(Op1, m_FSub(m_NegZero(), m_Value(X))))
855 if (FMF.noSignedZeros() && match(Op1, m_FSub(m_AnyZero(), m_Value(X))))
859 // fsub nnan ninf x, x ==> 0.0
860 if (FMF.noNaNs() && FMF.noInfs() && Op0 == Op1)
861 return Constant::getNullValue(Op0->getType());
866 /// Given the operands for an FMul, see if we can fold the result
867 static Value *SimplifyFMulInst(Value *Op0, Value *Op1,
870 unsigned MaxRecurse) {
871 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
872 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
873 Constant *Ops[] = { CLHS, CRHS };
874 return ConstantFoldInstOperands(Instruction::FMul, CLHS->getType(),
878 // Canonicalize the constant to the RHS.
883 if (match(Op1, m_FPOne()))
886 // fmul nnan nsz X, 0 ==> 0
887 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero()))
893 /// SimplifyMulInst - Given operands for a Mul, see if we can
894 /// fold the result. If not, this returns null.
895 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
896 unsigned MaxRecurse) {
897 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
898 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
899 Constant *Ops[] = { CLHS, CRHS };
900 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
904 // Canonicalize the constant to the RHS.
909 if (match(Op1, m_Undef()))
910 return Constant::getNullValue(Op0->getType());
913 if (match(Op1, m_Zero()))
917 if (match(Op1, m_One()))
920 // (X / Y) * Y -> X if the division is exact.
922 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
923 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
927 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
928 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
931 // Try some generic simplifications for associative operations.
932 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
936 // Mul distributes over Add. Try some generic simplifications based on this.
937 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
941 // If the operation is with the result of a select instruction, check whether
942 // operating on either branch of the select always yields the same value.
943 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
944 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
948 // If the operation is with the result of a phi instruction, check whether
949 // operating on all incoming values of the phi always yields the same value.
950 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
951 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
958 Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
959 const DataLayout &DL,
960 const TargetLibraryInfo *TLI,
961 const DominatorTree *DT, AssumptionCache *AC,
962 const Instruction *CxtI) {
963 return ::SimplifyFAddInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
967 Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
968 const DataLayout &DL,
969 const TargetLibraryInfo *TLI,
970 const DominatorTree *DT, AssumptionCache *AC,
971 const Instruction *CxtI) {
972 return ::SimplifyFSubInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
976 Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
977 const DataLayout &DL,
978 const TargetLibraryInfo *TLI,
979 const DominatorTree *DT, AssumptionCache *AC,
980 const Instruction *CxtI) {
981 return ::SimplifyFMulInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
985 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const DataLayout &DL,
986 const TargetLibraryInfo *TLI,
987 const DominatorTree *DT, AssumptionCache *AC,
988 const Instruction *CxtI) {
989 return ::SimplifyMulInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
993 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
994 /// fold the result. If not, this returns null.
995 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
996 const Query &Q, unsigned MaxRecurse) {
997 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
998 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
999 Constant *Ops[] = { C0, C1 };
1000 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1004 bool isSigned = Opcode == Instruction::SDiv;
1006 // X / undef -> undef
1007 if (match(Op1, m_Undef()))
1010 // X / 0 -> undef, we don't need to preserve faults!
1011 if (match(Op1, m_Zero()))
1012 return UndefValue::get(Op1->getType());
1015 if (match(Op0, m_Undef()))
1016 return Constant::getNullValue(Op0->getType());
1018 // 0 / X -> 0, we don't need to preserve faults!
1019 if (match(Op0, m_Zero()))
1023 if (match(Op1, m_One()))
1026 if (Op0->getType()->isIntegerTy(1))
1027 // It can't be division by zero, hence it must be division by one.
1032 return ConstantInt::get(Op0->getType(), 1);
1034 // (X * Y) / Y -> X if the multiplication does not overflow.
1035 Value *X = nullptr, *Y = nullptr;
1036 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
1037 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
1038 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
1039 // If the Mul knows it does not overflow, then we are good to go.
1040 if ((isSigned && Mul->hasNoSignedWrap()) ||
1041 (!isSigned && Mul->hasNoUnsignedWrap()))
1043 // If X has the form X = A / Y then X * Y cannot overflow.
1044 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
1045 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1049 // (X rem Y) / Y -> 0
1050 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1051 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1052 return Constant::getNullValue(Op0->getType());
1054 // (X /u C1) /u C2 -> 0 if C1 * C2 overflow
1055 ConstantInt *C1, *C2;
1056 if (!isSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
1057 match(Op1, m_ConstantInt(C2))) {
1059 C1->getValue().umul_ov(C2->getValue(), Overflow);
1061 return Constant::getNullValue(Op0->getType());
1064 // If the operation is with the result of a select instruction, check whether
1065 // operating on either branch of the select always yields the same value.
1066 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1067 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1070 // If the operation is with the result of a phi instruction, check whether
1071 // operating on all incoming values of the phi always yields the same value.
1072 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1073 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1079 /// SimplifySDivInst - Given operands for an SDiv, see if we can
1080 /// fold the result. If not, this returns null.
1081 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
1082 unsigned MaxRecurse) {
1083 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
1089 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const DataLayout &DL,
1090 const TargetLibraryInfo *TLI,
1091 const DominatorTree *DT, AssumptionCache *AC,
1092 const Instruction *CxtI) {
1093 return ::SimplifySDivInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1097 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
1098 /// fold the result. If not, this returns null.
1099 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
1100 unsigned MaxRecurse) {
1101 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
1107 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const DataLayout &DL,
1108 const TargetLibraryInfo *TLI,
1109 const DominatorTree *DT, AssumptionCache *AC,
1110 const Instruction *CxtI) {
1111 return ::SimplifyUDivInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1115 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
1116 const Query &Q, unsigned) {
1117 // undef / X -> undef (the undef could be a snan).
1118 if (match(Op0, m_Undef()))
1121 // X / undef -> undef
1122 if (match(Op1, m_Undef()))
1126 // Requires that NaNs are off (X could be zero) and signed zeroes are
1127 // ignored (X could be positive or negative, so the output sign is unknown).
1128 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
1134 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
1135 const DataLayout &DL,
1136 const TargetLibraryInfo *TLI,
1137 const DominatorTree *DT, AssumptionCache *AC,
1138 const Instruction *CxtI) {
1139 return ::SimplifyFDivInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
1143 /// SimplifyRem - Given operands for an SRem or URem, see if we can
1144 /// fold the result. If not, this returns null.
1145 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1146 const Query &Q, unsigned MaxRecurse) {
1147 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1148 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1149 Constant *Ops[] = { C0, C1 };
1150 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1154 // X % undef -> undef
1155 if (match(Op1, m_Undef()))
1159 if (match(Op0, m_Undef()))
1160 return Constant::getNullValue(Op0->getType());
1162 // 0 % X -> 0, we don't need to preserve faults!
1163 if (match(Op0, m_Zero()))
1166 // X % 0 -> undef, we don't need to preserve faults!
1167 if (match(Op1, m_Zero()))
1168 return UndefValue::get(Op0->getType());
1171 if (match(Op1, m_One()))
1172 return Constant::getNullValue(Op0->getType());
1174 if (Op0->getType()->isIntegerTy(1))
1175 // It can't be remainder by zero, hence it must be remainder by one.
1176 return Constant::getNullValue(Op0->getType());
1180 return Constant::getNullValue(Op0->getType());
1182 // (X % Y) % Y -> X % Y
1183 if ((Opcode == Instruction::SRem &&
1184 match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1185 (Opcode == Instruction::URem &&
1186 match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1189 // If the operation is with the result of a select instruction, check whether
1190 // operating on either branch of the select always yields the same value.
1191 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1192 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1195 // If the operation is with the result of a phi instruction, check whether
1196 // operating on all incoming values of the phi always yields the same value.
1197 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1198 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1204 /// SimplifySRemInst - Given operands for an SRem, see if we can
1205 /// fold the result. If not, this returns null.
1206 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
1207 unsigned MaxRecurse) {
1208 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
1214 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const DataLayout &DL,
1215 const TargetLibraryInfo *TLI,
1216 const DominatorTree *DT, AssumptionCache *AC,
1217 const Instruction *CxtI) {
1218 return ::SimplifySRemInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1222 /// SimplifyURemInst - Given operands for a URem, see if we can
1223 /// fold the result. If not, this returns null.
1224 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
1225 unsigned MaxRecurse) {
1226 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
1232 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const DataLayout &DL,
1233 const TargetLibraryInfo *TLI,
1234 const DominatorTree *DT, AssumptionCache *AC,
1235 const Instruction *CxtI) {
1236 return ::SimplifyURemInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1240 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
1241 const Query &, unsigned) {
1242 // undef % X -> undef (the undef could be a snan).
1243 if (match(Op0, m_Undef()))
1246 // X % undef -> undef
1247 if (match(Op1, m_Undef()))
1251 // Requires that NaNs are off (X could be zero) and signed zeroes are
1252 // ignored (X could be positive or negative, so the output sign is unknown).
1253 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
1259 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
1260 const DataLayout &DL,
1261 const TargetLibraryInfo *TLI,
1262 const DominatorTree *DT, AssumptionCache *AC,
1263 const Instruction *CxtI) {
1264 return ::SimplifyFRemInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
1268 /// isUndefShift - Returns true if a shift by \c Amount always yields undef.
1269 static bool isUndefShift(Value *Amount) {
1270 Constant *C = dyn_cast<Constant>(Amount);
1274 // X shift by undef -> undef because it may shift by the bitwidth.
1275 if (isa<UndefValue>(C))
1278 // Shifting by the bitwidth or more is undefined.
1279 if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
1280 if (CI->getValue().getLimitedValue() >=
1281 CI->getType()->getScalarSizeInBits())
1284 // If all lanes of a vector shift are undefined the whole shift is.
1285 if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
1286 for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I)
1287 if (!isUndefShift(C->getAggregateElement(I)))
1295 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1296 /// fold the result. If not, this returns null.
1297 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1298 const Query &Q, unsigned MaxRecurse) {
1299 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1300 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1301 Constant *Ops[] = { C0, C1 };
1302 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1306 // 0 shift by X -> 0
1307 if (match(Op0, m_Zero()))
1310 // X shift by 0 -> X
1311 if (match(Op1, m_Zero()))
1314 // Fold undefined shifts.
1315 if (isUndefShift(Op1))
1316 return UndefValue::get(Op0->getType());
1318 // If the operation is with the result of a select instruction, check whether
1319 // operating on either branch of the select always yields the same value.
1320 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1321 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1324 // If the operation is with the result of a phi instruction, check whether
1325 // operating on all incoming values of the phi always yields the same value.
1326 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1327 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1333 /// \brief Given operands for an Shl, LShr or AShr, see if we can
1334 /// fold the result. If not, this returns null.
1335 static Value *SimplifyRightShift(unsigned Opcode, Value *Op0, Value *Op1,
1336 bool isExact, const Query &Q,
1337 unsigned MaxRecurse) {
1338 if (Value *V = SimplifyShift(Opcode, Op0, Op1, Q, MaxRecurse))
1343 return Constant::getNullValue(Op0->getType());
1346 // undef >> X -> undef (if it's exact)
1347 if (match(Op0, m_Undef()))
1348 return isExact ? Op0 : Constant::getNullValue(Op0->getType());
1350 // The low bit cannot be shifted out of an exact shift if it is set.
1352 unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
1353 APInt Op0KnownZero(BitWidth, 0);
1354 APInt Op0KnownOne(BitWidth, 0);
1355 computeKnownBits(Op0, Op0KnownZero, Op0KnownOne, Q.DL, /*Depth=*/0, Q.AC,
1364 /// SimplifyShlInst - Given operands for an Shl, see if we can
1365 /// fold the result. If not, this returns null.
1366 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1367 const Query &Q, unsigned MaxRecurse) {
1368 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1372 // undef << X -> undef if (if it's NSW/NUW)
1373 if (match(Op0, m_Undef()))
1374 return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType());
1376 // (X >> A) << A -> X
1378 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1383 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1384 const DataLayout &DL, const TargetLibraryInfo *TLI,
1385 const DominatorTree *DT, AssumptionCache *AC,
1386 const Instruction *CxtI) {
1387 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
1391 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1392 /// fold the result. If not, this returns null.
1393 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1394 const Query &Q, unsigned MaxRecurse) {
1395 if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q,
1399 // (X << A) >> A -> X
1401 if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
1407 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1408 const DataLayout &DL,
1409 const TargetLibraryInfo *TLI,
1410 const DominatorTree *DT, AssumptionCache *AC,
1411 const Instruction *CxtI) {
1412 return ::SimplifyLShrInst(Op0, Op1, isExact, Query(DL, TLI, DT, AC, CxtI),
1416 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1417 /// fold the result. If not, this returns null.
1418 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1419 const Query &Q, unsigned MaxRecurse) {
1420 if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
1424 // all ones >>a X -> all ones
1425 if (match(Op0, m_AllOnes()))
1428 // (X << A) >> A -> X
1430 if (match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
1433 // Arithmetic shifting an all-sign-bit value is a no-op.
1434 unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1435 if (NumSignBits == Op0->getType()->getScalarSizeInBits())
1441 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1442 const DataLayout &DL,
1443 const TargetLibraryInfo *TLI,
1444 const DominatorTree *DT, AssumptionCache *AC,
1445 const Instruction *CxtI) {
1446 return ::SimplifyAShrInst(Op0, Op1, isExact, Query(DL, TLI, DT, AC, CxtI),
1450 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp,
1451 ICmpInst *UnsignedICmp, bool IsAnd) {
1454 ICmpInst::Predicate EqPred;
1455 if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) ||
1456 !ICmpInst::isEquality(EqPred))
1459 ICmpInst::Predicate UnsignedPred;
1460 if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
1461 ICmpInst::isUnsigned(UnsignedPred))
1463 else if (match(UnsignedICmp,
1464 m_ICmp(UnsignedPred, m_Value(Y), m_Specific(X))) &&
1465 ICmpInst::isUnsigned(UnsignedPred))
1466 UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
1470 // X < Y && Y != 0 --> X < Y
1471 // X < Y || Y != 0 --> Y != 0
1472 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE)
1473 return IsAnd ? UnsignedICmp : ZeroICmp;
1475 // X >= Y || Y != 0 --> true
1476 // X >= Y || Y == 0 --> X >= Y
1477 if (UnsignedPred == ICmpInst::ICMP_UGE && !IsAnd) {
1478 if (EqPred == ICmpInst::ICMP_NE)
1479 return getTrue(UnsignedICmp->getType());
1480 return UnsignedICmp;
1483 // X < Y && Y == 0 --> false
1484 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
1486 return getFalse(UnsignedICmp->getType());
1491 // Simplify (and (icmp ...) (icmp ...)) to true when we can tell that the range
1492 // of possible values cannot be satisfied.
1493 static Value *SimplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
1494 ICmpInst::Predicate Pred0, Pred1;
1495 ConstantInt *CI1, *CI2;
1498 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true))
1501 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
1502 m_ConstantInt(CI2))))
1505 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
1508 Type *ITy = Op0->getType();
1510 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1511 bool isNSW = AddInst->hasNoSignedWrap();
1512 bool isNUW = AddInst->hasNoUnsignedWrap();
1514 const APInt &CI1V = CI1->getValue();
1515 const APInt &CI2V = CI2->getValue();
1516 const APInt Delta = CI2V - CI1V;
1517 if (CI1V.isStrictlyPositive()) {
1519 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
1520 return getFalse(ITy);
1521 if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1522 return getFalse(ITy);
1525 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
1526 return getFalse(ITy);
1527 if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1528 return getFalse(ITy);
1531 if (CI1V.getBoolValue() && isNUW) {
1533 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
1534 return getFalse(ITy);
1536 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
1537 return getFalse(ITy);
1543 /// SimplifyAndInst - Given operands for an And, see if we can
1544 /// fold the result. If not, this returns null.
1545 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
1546 unsigned MaxRecurse) {
1547 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1548 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1549 Constant *Ops[] = { CLHS, CRHS };
1550 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1554 // Canonicalize the constant to the RHS.
1555 std::swap(Op0, Op1);
1559 if (match(Op1, m_Undef()))
1560 return Constant::getNullValue(Op0->getType());
1567 if (match(Op1, m_Zero()))
1571 if (match(Op1, m_AllOnes()))
1574 // A & ~A = ~A & A = 0
1575 if (match(Op0, m_Not(m_Specific(Op1))) ||
1576 match(Op1, m_Not(m_Specific(Op0))))
1577 return Constant::getNullValue(Op0->getType());
1580 Value *A = nullptr, *B = nullptr;
1581 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1582 (A == Op1 || B == Op1))
1586 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1587 (A == Op0 || B == Op0))
1590 // A & (-A) = A if A is a power of two or zero.
1591 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1592 match(Op1, m_Neg(m_Specific(Op0)))) {
1593 if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1596 if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1601 if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
1602 if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
1603 if (Value *V = SimplifyAndOfICmps(ICILHS, ICIRHS))
1605 if (Value *V = SimplifyAndOfICmps(ICIRHS, ICILHS))
1610 // Try some generic simplifications for associative operations.
1611 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1615 // And distributes over Or. Try some generic simplifications based on this.
1616 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1620 // And distributes over Xor. Try some generic simplifications based on this.
1621 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1625 // If the operation is with the result of a select instruction, check whether
1626 // operating on either branch of the select always yields the same value.
1627 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1628 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1632 // If the operation is with the result of a phi instruction, check whether
1633 // operating on all incoming values of the phi always yields the same value.
1634 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1635 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1642 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout &DL,
1643 const TargetLibraryInfo *TLI,
1644 const DominatorTree *DT, AssumptionCache *AC,
1645 const Instruction *CxtI) {
1646 return ::SimplifyAndInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1650 // Simplify (or (icmp ...) (icmp ...)) to true when we can tell that the union
1651 // contains all possible values.
1652 static Value *SimplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
1653 ICmpInst::Predicate Pred0, Pred1;
1654 ConstantInt *CI1, *CI2;
1657 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false))
1660 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
1661 m_ConstantInt(CI2))))
1664 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
1667 Type *ITy = Op0->getType();
1669 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1670 bool isNSW = AddInst->hasNoSignedWrap();
1671 bool isNUW = AddInst->hasNoUnsignedWrap();
1673 const APInt &CI1V = CI1->getValue();
1674 const APInt &CI2V = CI2->getValue();
1675 const APInt Delta = CI2V - CI1V;
1676 if (CI1V.isStrictlyPositive()) {
1678 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
1679 return getTrue(ITy);
1680 if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1681 return getTrue(ITy);
1684 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
1685 return getTrue(ITy);
1686 if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1687 return getTrue(ITy);
1690 if (CI1V.getBoolValue() && isNUW) {
1692 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
1693 return getTrue(ITy);
1695 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
1696 return getTrue(ITy);
1702 /// SimplifyOrInst - Given operands for an Or, see if we can
1703 /// fold the result. If not, this returns null.
1704 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
1705 unsigned MaxRecurse) {
1706 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1707 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1708 Constant *Ops[] = { CLHS, CRHS };
1709 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1713 // Canonicalize the constant to the RHS.
1714 std::swap(Op0, Op1);
1718 if (match(Op1, m_Undef()))
1719 return Constant::getAllOnesValue(Op0->getType());
1726 if (match(Op1, m_Zero()))
1730 if (match(Op1, m_AllOnes()))
1733 // A | ~A = ~A | A = -1
1734 if (match(Op0, m_Not(m_Specific(Op1))) ||
1735 match(Op1, m_Not(m_Specific(Op0))))
1736 return Constant::getAllOnesValue(Op0->getType());
1739 Value *A = nullptr, *B = nullptr;
1740 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1741 (A == Op1 || B == Op1))
1745 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1746 (A == Op0 || B == Op0))
1749 // ~(A & ?) | A = -1
1750 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1751 (A == Op1 || B == Op1))
1752 return Constant::getAllOnesValue(Op1->getType());
1754 // A | ~(A & ?) = -1
1755 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1756 (A == Op0 || B == Op0))
1757 return Constant::getAllOnesValue(Op0->getType());
1759 if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
1760 if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
1761 if (Value *V = SimplifyOrOfICmps(ICILHS, ICIRHS))
1763 if (Value *V = SimplifyOrOfICmps(ICIRHS, ICILHS))
1768 // Try some generic simplifications for associative operations.
1769 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1773 // Or distributes over And. Try some generic simplifications based on this.
1774 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1778 // If the operation is with the result of a select instruction, check whether
1779 // operating on either branch of the select always yields the same value.
1780 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1781 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1786 Value *C = nullptr, *D = nullptr;
1787 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
1788 match(Op1, m_And(m_Value(B), m_Value(D)))) {
1789 ConstantInt *C1 = dyn_cast<ConstantInt>(C);
1790 ConstantInt *C2 = dyn_cast<ConstantInt>(D);
1791 if (C1 && C2 && (C1->getValue() == ~C2->getValue())) {
1792 // (A & C1)|(B & C2)
1793 // If we have: ((V + N) & C1) | (V & C2)
1794 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1795 // replace with V+N.
1797 if ((C2->getValue() & (C2->getValue() + 1)) == 0 && // C2 == 0+1+
1798 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
1799 // Add commutes, try both ways.
1801 MaskedValueIsZero(V2, C2->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1804 MaskedValueIsZero(V1, C2->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1807 // Or commutes, try both ways.
1808 if ((C1->getValue() & (C1->getValue() + 1)) == 0 &&
1809 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
1810 // Add commutes, try both ways.
1812 MaskedValueIsZero(V2, C1->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1815 MaskedValueIsZero(V1, C1->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1821 // If the operation is with the result of a phi instruction, check whether
1822 // operating on all incoming values of the phi always yields the same value.
1823 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1824 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1830 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const DataLayout &DL,
1831 const TargetLibraryInfo *TLI,
1832 const DominatorTree *DT, AssumptionCache *AC,
1833 const Instruction *CxtI) {
1834 return ::SimplifyOrInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1838 /// SimplifyXorInst - Given operands for a Xor, see if we can
1839 /// fold the result. If not, this returns null.
1840 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q,
1841 unsigned MaxRecurse) {
1842 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1843 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1844 Constant *Ops[] = { CLHS, CRHS };
1845 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1849 // Canonicalize the constant to the RHS.
1850 std::swap(Op0, Op1);
1853 // A ^ undef -> undef
1854 if (match(Op1, m_Undef()))
1858 if (match(Op1, m_Zero()))
1863 return Constant::getNullValue(Op0->getType());
1865 // A ^ ~A = ~A ^ A = -1
1866 if (match(Op0, m_Not(m_Specific(Op1))) ||
1867 match(Op1, m_Not(m_Specific(Op0))))
1868 return Constant::getAllOnesValue(Op0->getType());
1870 // Try some generic simplifications for associative operations.
1871 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1875 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1876 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1877 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1878 // only if B and C are equal. If B and C are equal then (since we assume
1879 // that operands have already been simplified) "select(cond, B, C)" should
1880 // have been simplified to the common value of B and C already. Analysing
1881 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1882 // for threading over phi nodes.
1887 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const DataLayout &DL,
1888 const TargetLibraryInfo *TLI,
1889 const DominatorTree *DT, AssumptionCache *AC,
1890 const Instruction *CxtI) {
1891 return ::SimplifyXorInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1895 static Type *GetCompareTy(Value *Op) {
1896 return CmpInst::makeCmpResultType(Op->getType());
1899 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1900 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1901 /// otherwise return null. Helper function for analyzing max/min idioms.
1902 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1903 Value *LHS, Value *RHS) {
1904 SelectInst *SI = dyn_cast<SelectInst>(V);
1907 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1910 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1911 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1913 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1914 LHS == CmpRHS && RHS == CmpLHS)
1919 // A significant optimization not implemented here is assuming that alloca
1920 // addresses are not equal to incoming argument values. They don't *alias*,
1921 // as we say, but that doesn't mean they aren't equal, so we take a
1922 // conservative approach.
1924 // This is inspired in part by C++11 5.10p1:
1925 // "Two pointers of the same type compare equal if and only if they are both
1926 // null, both point to the same function, or both represent the same
1929 // This is pretty permissive.
1931 // It's also partly due to C11 6.5.9p6:
1932 // "Two pointers compare equal if and only if both are null pointers, both are
1933 // pointers to the same object (including a pointer to an object and a
1934 // subobject at its beginning) or function, both are pointers to one past the
1935 // last element of the same array object, or one is a pointer to one past the
1936 // end of one array object and the other is a pointer to the start of a
1937 // different array object that happens to immediately follow the first array
1938 // object in the address space.)
1940 // C11's version is more restrictive, however there's no reason why an argument
1941 // couldn't be a one-past-the-end value for a stack object in the caller and be
1942 // equal to the beginning of a stack object in the callee.
1944 // If the C and C++ standards are ever made sufficiently restrictive in this
1945 // area, it may be possible to update LLVM's semantics accordingly and reinstate
1946 // this optimization.
1947 static Constant *computePointerICmp(const DataLayout &DL,
1948 const TargetLibraryInfo *TLI,
1949 CmpInst::Predicate Pred, Value *LHS,
1951 // First, skip past any trivial no-ops.
1952 LHS = LHS->stripPointerCasts();
1953 RHS = RHS->stripPointerCasts();
1955 // A non-null pointer is not equal to a null pointer.
1956 if (llvm::isKnownNonNull(LHS, TLI) && isa<ConstantPointerNull>(RHS) &&
1957 (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE))
1958 return ConstantInt::get(GetCompareTy(LHS),
1959 !CmpInst::isTrueWhenEqual(Pred));
1961 // We can only fold certain predicates on pointer comparisons.
1966 // Equality comaprisons are easy to fold.
1967 case CmpInst::ICMP_EQ:
1968 case CmpInst::ICMP_NE:
1971 // We can only handle unsigned relational comparisons because 'inbounds' on
1972 // a GEP only protects against unsigned wrapping.
1973 case CmpInst::ICMP_UGT:
1974 case CmpInst::ICMP_UGE:
1975 case CmpInst::ICMP_ULT:
1976 case CmpInst::ICMP_ULE:
1977 // However, we have to switch them to their signed variants to handle
1978 // negative indices from the base pointer.
1979 Pred = ICmpInst::getSignedPredicate(Pred);
1983 // Strip off any constant offsets so that we can reason about them.
1984 // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
1985 // here and compare base addresses like AliasAnalysis does, however there are
1986 // numerous hazards. AliasAnalysis and its utilities rely on special rules
1987 // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
1988 // doesn't need to guarantee pointer inequality when it says NoAlias.
1989 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
1990 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
1992 // If LHS and RHS are related via constant offsets to the same base
1993 // value, we can replace it with an icmp which just compares the offsets.
1995 return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
1997 // Various optimizations for (in)equality comparisons.
1998 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
1999 // Different non-empty allocations that exist at the same time have
2000 // different addresses (if the program can tell). Global variables always
2001 // exist, so they always exist during the lifetime of each other and all
2002 // allocas. Two different allocas usually have different addresses...
2004 // However, if there's an @llvm.stackrestore dynamically in between two
2005 // allocas, they may have the same address. It's tempting to reduce the
2006 // scope of the problem by only looking at *static* allocas here. That would
2007 // cover the majority of allocas while significantly reducing the likelihood
2008 // of having an @llvm.stackrestore pop up in the middle. However, it's not
2009 // actually impossible for an @llvm.stackrestore to pop up in the middle of
2010 // an entry block. Also, if we have a block that's not attached to a
2011 // function, we can't tell if it's "static" under the current definition.
2012 // Theoretically, this problem could be fixed by creating a new kind of
2013 // instruction kind specifically for static allocas. Such a new instruction
2014 // could be required to be at the top of the entry block, thus preventing it
2015 // from being subject to a @llvm.stackrestore. Instcombine could even
2016 // convert regular allocas into these special allocas. It'd be nifty.
2017 // However, until then, this problem remains open.
2019 // So, we'll assume that two non-empty allocas have different addresses
2022 // With all that, if the offsets are within the bounds of their allocations
2023 // (and not one-past-the-end! so we can't use inbounds!), and their
2024 // allocations aren't the same, the pointers are not equal.
2026 // Note that it's not necessary to check for LHS being a global variable
2027 // address, due to canonicalization and constant folding.
2028 if (isa<AllocaInst>(LHS) &&
2029 (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
2030 ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
2031 ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
2032 uint64_t LHSSize, RHSSize;
2033 if (LHSOffsetCI && RHSOffsetCI &&
2034 getObjectSize(LHS, LHSSize, DL, TLI) &&
2035 getObjectSize(RHS, RHSSize, DL, TLI)) {
2036 const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
2037 const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
2038 if (!LHSOffsetValue.isNegative() &&
2039 !RHSOffsetValue.isNegative() &&
2040 LHSOffsetValue.ult(LHSSize) &&
2041 RHSOffsetValue.ult(RHSSize)) {
2042 return ConstantInt::get(GetCompareTy(LHS),
2043 !CmpInst::isTrueWhenEqual(Pred));
2047 // Repeat the above check but this time without depending on DataLayout
2048 // or being able to compute a precise size.
2049 if (!cast<PointerType>(LHS->getType())->isEmptyTy() &&
2050 !cast<PointerType>(RHS->getType())->isEmptyTy() &&
2051 LHSOffset->isNullValue() &&
2052 RHSOffset->isNullValue())
2053 return ConstantInt::get(GetCompareTy(LHS),
2054 !CmpInst::isTrueWhenEqual(Pred));
2057 // Even if an non-inbounds GEP occurs along the path we can still optimize
2058 // equality comparisons concerning the result. We avoid walking the whole
2059 // chain again by starting where the last calls to
2060 // stripAndComputeConstantOffsets left off and accumulate the offsets.
2061 Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true);
2062 Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true);
2064 return ConstantExpr::getICmp(Pred,
2065 ConstantExpr::getAdd(LHSOffset, LHSNoBound),
2066 ConstantExpr::getAdd(RHSOffset, RHSNoBound));
2068 // If one side of the equality comparison must come from a noalias call
2069 // (meaning a system memory allocation function), and the other side must
2070 // come from a pointer that cannot overlap with dynamically-allocated
2071 // memory within the lifetime of the current function (allocas, byval
2072 // arguments, globals), then determine the comparison result here.
2073 SmallVector<Value *, 8> LHSUObjs, RHSUObjs;
2074 GetUnderlyingObjects(LHS, LHSUObjs, DL);
2075 GetUnderlyingObjects(RHS, RHSUObjs, DL);
2077 // Is the set of underlying objects all noalias calls?
2078 auto IsNAC = [](SmallVectorImpl<Value *> &Objects) {
2079 return std::all_of(Objects.begin(), Objects.end(),
2080 [](Value *V){ return isNoAliasCall(V); });
2083 // Is the set of underlying objects all things which must be disjoint from
2084 // noalias calls. For allocas, we consider only static ones (dynamic
2085 // allocas might be transformed into calls to malloc not simultaneously
2086 // live with the compared-to allocation). For globals, we exclude symbols
2087 // that might be resolve lazily to symbols in another dynamically-loaded
2088 // library (and, thus, could be malloc'ed by the implementation).
2089 auto IsAllocDisjoint = [](SmallVectorImpl<Value *> &Objects) {
2090 return std::all_of(Objects.begin(), Objects.end(),
2092 if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
2093 return AI->getParent() && AI->getParent()->getParent() &&
2094 AI->isStaticAlloca();
2095 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
2096 return (GV->hasLocalLinkage() ||
2097 GV->hasHiddenVisibility() ||
2098 GV->hasProtectedVisibility() ||
2099 GV->hasUnnamedAddr()) &&
2100 !GV->isThreadLocal();
2101 if (const Argument *A = dyn_cast<Argument>(V))
2102 return A->hasByValAttr();
2107 if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
2108 (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
2109 return ConstantInt::get(GetCompareTy(LHS),
2110 !CmpInst::isTrueWhenEqual(Pred));
2117 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
2118 /// fold the result. If not, this returns null.
2119 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2120 const Query &Q, unsigned MaxRecurse) {
2121 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2122 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
2124 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2125 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2126 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
2128 // If we have a constant, make sure it is on the RHS.
2129 std::swap(LHS, RHS);
2130 Pred = CmpInst::getSwappedPredicate(Pred);
2133 Type *ITy = GetCompareTy(LHS); // The return type.
2134 Type *OpTy = LHS->getType(); // The operand type.
2136 // icmp X, X -> true/false
2137 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
2138 // because X could be 0.
2139 if (LHS == RHS || isa<UndefValue>(RHS))
2140 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
2142 // Special case logic when the operands have i1 type.
2143 if (OpTy->getScalarType()->isIntegerTy(1)) {
2146 case ICmpInst::ICMP_EQ:
2148 if (match(RHS, m_One()))
2151 case ICmpInst::ICMP_NE:
2153 if (match(RHS, m_Zero()))
2156 case ICmpInst::ICMP_UGT:
2158 if (match(RHS, m_Zero()))
2161 case ICmpInst::ICMP_UGE:
2163 if (match(RHS, m_One()))
2166 case ICmpInst::ICMP_SLT:
2168 if (match(RHS, m_Zero()))
2171 case ICmpInst::ICMP_SLE:
2173 if (match(RHS, m_One()))
2179 // If we are comparing with zero then try hard since this is a common case.
2180 if (match(RHS, m_Zero())) {
2181 bool LHSKnownNonNegative, LHSKnownNegative;
2183 default: llvm_unreachable("Unknown ICmp predicate!");
2184 case ICmpInst::ICMP_ULT:
2185 return getFalse(ITy);
2186 case ICmpInst::ICMP_UGE:
2187 return getTrue(ITy);
2188 case ICmpInst::ICMP_EQ:
2189 case ICmpInst::ICMP_ULE:
2190 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2191 return getFalse(ITy);
2193 case ICmpInst::ICMP_NE:
2194 case ICmpInst::ICMP_UGT:
2195 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2196 return getTrue(ITy);
2198 case ICmpInst::ICMP_SLT:
2199 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2201 if (LHSKnownNegative)
2202 return getTrue(ITy);
2203 if (LHSKnownNonNegative)
2204 return getFalse(ITy);
2206 case ICmpInst::ICMP_SLE:
2207 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2209 if (LHSKnownNegative)
2210 return getTrue(ITy);
2211 if (LHSKnownNonNegative &&
2212 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2213 return getFalse(ITy);
2215 case ICmpInst::ICMP_SGE:
2216 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2218 if (LHSKnownNegative)
2219 return getFalse(ITy);
2220 if (LHSKnownNonNegative)
2221 return getTrue(ITy);
2223 case ICmpInst::ICMP_SGT:
2224 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2226 if (LHSKnownNegative)
2227 return getFalse(ITy);
2228 if (LHSKnownNonNegative &&
2229 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2230 return getTrue(ITy);
2235 // See if we are doing a comparison with a constant integer.
2236 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2237 // Rule out tautological comparisons (eg., ult 0 or uge 0).
2238 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
2239 if (RHS_CR.isEmptySet())
2240 return ConstantInt::getFalse(CI->getContext());
2241 if (RHS_CR.isFullSet())
2242 return ConstantInt::getTrue(CI->getContext());
2244 // Many binary operators with constant RHS have easy to compute constant
2245 // range. Use them to check whether the comparison is a tautology.
2246 unsigned Width = CI->getBitWidth();
2247 APInt Lower = APInt(Width, 0);
2248 APInt Upper = APInt(Width, 0);
2250 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
2251 // 'urem x, CI2' produces [0, CI2).
2252 Upper = CI2->getValue();
2253 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
2254 // 'srem x, CI2' produces (-|CI2|, |CI2|).
2255 Upper = CI2->getValue().abs();
2256 Lower = (-Upper) + 1;
2257 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
2258 // 'udiv CI2, x' produces [0, CI2].
2259 Upper = CI2->getValue() + 1;
2260 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
2261 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
2262 APInt NegOne = APInt::getAllOnesValue(Width);
2264 Upper = NegOne.udiv(CI2->getValue()) + 1;
2265 } else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) {
2266 if (CI2->isMinSignedValue()) {
2267 // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
2268 Lower = CI2->getValue();
2269 Upper = Lower.lshr(1) + 1;
2271 // 'sdiv CI2, x' produces [-|CI2|, |CI2|].
2272 Upper = CI2->getValue().abs() + 1;
2273 Lower = (-Upper) + 1;
2275 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
2276 APInt IntMin = APInt::getSignedMinValue(Width);
2277 APInt IntMax = APInt::getSignedMaxValue(Width);
2278 APInt Val = CI2->getValue();
2279 if (Val.isAllOnesValue()) {
2280 // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
2281 // where CI2 != -1 and CI2 != 0 and CI2 != 1
2284 } else if (Val.countLeadingZeros() < Width - 1) {
2285 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]
2286 // where CI2 != -1 and CI2 != 0 and CI2 != 1
2287 Lower = IntMin.sdiv(Val);
2288 Upper = IntMax.sdiv(Val);
2289 if (Lower.sgt(Upper))
2290 std::swap(Lower, Upper);
2292 assert(Upper != Lower && "Upper part of range has wrapped!");
2294 } else if (match(LHS, m_NUWShl(m_ConstantInt(CI2), m_Value()))) {
2295 // 'shl nuw CI2, x' produces [CI2, CI2 << CLZ(CI2)]
2296 Lower = CI2->getValue();
2297 Upper = Lower.shl(Lower.countLeadingZeros()) + 1;
2298 } else if (match(LHS, m_NSWShl(m_ConstantInt(CI2), m_Value()))) {
2299 if (CI2->isNegative()) {
2300 // 'shl nsw CI2, x' produces [CI2 << CLO(CI2)-1, CI2]
2301 unsigned ShiftAmount = CI2->getValue().countLeadingOnes() - 1;
2302 Lower = CI2->getValue().shl(ShiftAmount);
2303 Upper = CI2->getValue() + 1;
2305 // 'shl nsw CI2, x' produces [CI2, CI2 << CLZ(CI2)-1]
2306 unsigned ShiftAmount = CI2->getValue().countLeadingZeros() - 1;
2307 Lower = CI2->getValue();
2308 Upper = CI2->getValue().shl(ShiftAmount) + 1;
2310 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
2311 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
2312 APInt NegOne = APInt::getAllOnesValue(Width);
2313 if (CI2->getValue().ult(Width))
2314 Upper = NegOne.lshr(CI2->getValue()) + 1;
2315 } else if (match(LHS, m_LShr(m_ConstantInt(CI2), m_Value()))) {
2316 // 'lshr CI2, x' produces [CI2 >> (Width-1), CI2].
2317 unsigned ShiftAmount = Width - 1;
2318 if (!CI2->isZero() && cast<BinaryOperator>(LHS)->isExact())
2319 ShiftAmount = CI2->getValue().countTrailingZeros();
2320 Lower = CI2->getValue().lshr(ShiftAmount);
2321 Upper = CI2->getValue() + 1;
2322 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
2323 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
2324 APInt IntMin = APInt::getSignedMinValue(Width);
2325 APInt IntMax = APInt::getSignedMaxValue(Width);
2326 if (CI2->getValue().ult(Width)) {
2327 Lower = IntMin.ashr(CI2->getValue());
2328 Upper = IntMax.ashr(CI2->getValue()) + 1;
2330 } else if (match(LHS, m_AShr(m_ConstantInt(CI2), m_Value()))) {
2331 unsigned ShiftAmount = Width - 1;
2332 if (!CI2->isZero() && cast<BinaryOperator>(LHS)->isExact())
2333 ShiftAmount = CI2->getValue().countTrailingZeros();
2334 if (CI2->isNegative()) {
2335 // 'ashr CI2, x' produces [CI2, CI2 >> (Width-1)]
2336 Lower = CI2->getValue();
2337 Upper = CI2->getValue().ashr(ShiftAmount) + 1;
2339 // 'ashr CI2, x' produces [CI2 >> (Width-1), CI2]
2340 Lower = CI2->getValue().ashr(ShiftAmount);
2341 Upper = CI2->getValue() + 1;
2343 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
2344 // 'or x, CI2' produces [CI2, UINT_MAX].
2345 Lower = CI2->getValue();
2346 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
2347 // 'and x, CI2' produces [0, CI2].
2348 Upper = CI2->getValue() + 1;
2350 if (Lower != Upper) {
2351 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
2352 if (RHS_CR.contains(LHS_CR))
2353 return ConstantInt::getTrue(RHS->getContext());
2354 if (RHS_CR.inverse().contains(LHS_CR))
2355 return ConstantInt::getFalse(RHS->getContext());
2359 // Compare of cast, for example (zext X) != 0 -> X != 0
2360 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
2361 Instruction *LI = cast<CastInst>(LHS);
2362 Value *SrcOp = LI->getOperand(0);
2363 Type *SrcTy = SrcOp->getType();
2364 Type *DstTy = LI->getType();
2366 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
2367 // if the integer type is the same size as the pointer type.
2368 if (MaxRecurse && isa<PtrToIntInst>(LI) &&
2369 Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
2370 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2371 // Transfer the cast to the constant.
2372 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
2373 ConstantExpr::getIntToPtr(RHSC, SrcTy),
2376 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
2377 if (RI->getOperand(0)->getType() == SrcTy)
2378 // Compare without the cast.
2379 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
2385 if (isa<ZExtInst>(LHS)) {
2386 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
2388 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
2389 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
2390 // Compare X and Y. Note that signed predicates become unsigned.
2391 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
2392 SrcOp, RI->getOperand(0), Q,
2396 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
2397 // too. If not, then try to deduce the result of the comparison.
2398 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2399 // Compute the constant that would happen if we truncated to SrcTy then
2400 // reextended to DstTy.
2401 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
2402 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
2404 // If the re-extended constant didn't change then this is effectively
2405 // also a case of comparing two zero-extended values.
2406 if (RExt == CI && MaxRecurse)
2407 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
2408 SrcOp, Trunc, Q, MaxRecurse-1))
2411 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
2412 // there. Use this to work out the result of the comparison.
2415 default: llvm_unreachable("Unknown ICmp predicate!");
2417 case ICmpInst::ICMP_EQ:
2418 case ICmpInst::ICMP_UGT:
2419 case ICmpInst::ICMP_UGE:
2420 return ConstantInt::getFalse(CI->getContext());
2422 case ICmpInst::ICMP_NE:
2423 case ICmpInst::ICMP_ULT:
2424 case ICmpInst::ICMP_ULE:
2425 return ConstantInt::getTrue(CI->getContext());
2427 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
2428 // is non-negative then LHS <s RHS.
2429 case ICmpInst::ICMP_SGT:
2430 case ICmpInst::ICMP_SGE:
2431 return CI->getValue().isNegative() ?
2432 ConstantInt::getTrue(CI->getContext()) :
2433 ConstantInt::getFalse(CI->getContext());
2435 case ICmpInst::ICMP_SLT:
2436 case ICmpInst::ICMP_SLE:
2437 return CI->getValue().isNegative() ?
2438 ConstantInt::getFalse(CI->getContext()) :
2439 ConstantInt::getTrue(CI->getContext());
2445 if (isa<SExtInst>(LHS)) {
2446 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
2448 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
2449 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
2450 // Compare X and Y. Note that the predicate does not change.
2451 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
2455 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
2456 // too. If not, then try to deduce the result of the comparison.
2457 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2458 // Compute the constant that would happen if we truncated to SrcTy then
2459 // reextended to DstTy.
2460 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
2461 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
2463 // If the re-extended constant didn't change then this is effectively
2464 // also a case of comparing two sign-extended values.
2465 if (RExt == CI && MaxRecurse)
2466 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
2469 // Otherwise the upper bits of LHS are all equal, while RHS has varying
2470 // bits there. Use this to work out the result of the comparison.
2473 default: llvm_unreachable("Unknown ICmp predicate!");
2474 case ICmpInst::ICMP_EQ:
2475 return ConstantInt::getFalse(CI->getContext());
2476 case ICmpInst::ICMP_NE:
2477 return ConstantInt::getTrue(CI->getContext());
2479 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
2481 case ICmpInst::ICMP_SGT:
2482 case ICmpInst::ICMP_SGE:
2483 return CI->getValue().isNegative() ?
2484 ConstantInt::getTrue(CI->getContext()) :
2485 ConstantInt::getFalse(CI->getContext());
2486 case ICmpInst::ICMP_SLT:
2487 case ICmpInst::ICMP_SLE:
2488 return CI->getValue().isNegative() ?
2489 ConstantInt::getFalse(CI->getContext()) :
2490 ConstantInt::getTrue(CI->getContext());
2492 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
2494 case ICmpInst::ICMP_UGT:
2495 case ICmpInst::ICMP_UGE:
2496 // Comparison is true iff the LHS <s 0.
2498 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
2499 Constant::getNullValue(SrcTy),
2503 case ICmpInst::ICMP_ULT:
2504 case ICmpInst::ICMP_ULE:
2505 // Comparison is true iff the LHS >=s 0.
2507 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
2508 Constant::getNullValue(SrcTy),
2518 // Special logic for binary operators.
2519 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2520 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2521 if (MaxRecurse && (LBO || RBO)) {
2522 // Analyze the case when either LHS or RHS is an add instruction.
2523 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2524 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2525 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2526 if (LBO && LBO->getOpcode() == Instruction::Add) {
2527 A = LBO->getOperand(0); B = LBO->getOperand(1);
2528 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
2529 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
2530 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
2532 if (RBO && RBO->getOpcode() == Instruction::Add) {
2533 C = RBO->getOperand(0); D = RBO->getOperand(1);
2534 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
2535 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2536 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2539 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2540 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2541 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2542 Constant::getNullValue(RHS->getType()),
2546 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2547 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2548 if (Value *V = SimplifyICmpInst(Pred,
2549 Constant::getNullValue(LHS->getType()),
2550 C == LHS ? D : C, Q, MaxRecurse-1))
2553 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2554 if (A && C && (A == C || A == D || B == C || B == D) &&
2555 NoLHSWrapProblem && NoRHSWrapProblem) {
2556 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2559 // C + B == C + D -> B == D
2562 } else if (A == D) {
2563 // D + B == C + D -> B == C
2566 } else if (B == C) {
2567 // A + C == C + D -> A == D
2572 // A + D == C + D -> A == C
2576 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
2581 // icmp pred (or X, Y), X
2582 if (LBO && match(LBO, m_CombineOr(m_Or(m_Value(), m_Specific(RHS)),
2583 m_Or(m_Specific(RHS), m_Value())))) {
2584 if (Pred == ICmpInst::ICMP_ULT)
2585 return getFalse(ITy);
2586 if (Pred == ICmpInst::ICMP_UGE)
2587 return getTrue(ITy);
2589 // icmp pred X, (or X, Y)
2590 if (RBO && match(RBO, m_CombineOr(m_Or(m_Value(), m_Specific(LHS)),
2591 m_Or(m_Specific(LHS), m_Value())))) {
2592 if (Pred == ICmpInst::ICMP_ULE)
2593 return getTrue(ITy);
2594 if (Pred == ICmpInst::ICMP_UGT)
2595 return getFalse(ITy);
2598 // icmp pred (and X, Y), X
2599 if (LBO && match(LBO, m_CombineOr(m_And(m_Value(), m_Specific(RHS)),
2600 m_And(m_Specific(RHS), m_Value())))) {
2601 if (Pred == ICmpInst::ICMP_UGT)
2602 return getFalse(ITy);
2603 if (Pred == ICmpInst::ICMP_ULE)
2604 return getTrue(ITy);
2606 // icmp pred X, (and X, Y)
2607 if (RBO && match(RBO, m_CombineOr(m_And(m_Value(), m_Specific(LHS)),
2608 m_And(m_Specific(LHS), m_Value())))) {
2609 if (Pred == ICmpInst::ICMP_UGE)
2610 return getTrue(ITy);
2611 if (Pred == ICmpInst::ICMP_ULT)
2612 return getFalse(ITy);
2615 // 0 - (zext X) pred C
2616 if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
2617 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
2618 if (RHSC->getValue().isStrictlyPositive()) {
2619 if (Pred == ICmpInst::ICMP_SLT)
2620 return ConstantInt::getTrue(RHSC->getContext());
2621 if (Pred == ICmpInst::ICMP_SGE)
2622 return ConstantInt::getFalse(RHSC->getContext());
2623 if (Pred == ICmpInst::ICMP_EQ)
2624 return ConstantInt::getFalse(RHSC->getContext());
2625 if (Pred == ICmpInst::ICMP_NE)
2626 return ConstantInt::getTrue(RHSC->getContext());
2628 if (RHSC->getValue().isNonNegative()) {
2629 if (Pred == ICmpInst::ICMP_SLE)
2630 return ConstantInt::getTrue(RHSC->getContext());
2631 if (Pred == ICmpInst::ICMP_SGT)
2632 return ConstantInt::getFalse(RHSC->getContext());
2637 // icmp pred (urem X, Y), Y
2638 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2639 bool KnownNonNegative, KnownNegative;
2643 case ICmpInst::ICMP_SGT:
2644 case ICmpInst::ICMP_SGE:
2645 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2647 if (!KnownNonNegative)
2650 case ICmpInst::ICMP_EQ:
2651 case ICmpInst::ICMP_UGT:
2652 case ICmpInst::ICMP_UGE:
2653 return getFalse(ITy);
2654 case ICmpInst::ICMP_SLT:
2655 case ICmpInst::ICMP_SLE:
2656 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2658 if (!KnownNonNegative)
2661 case ICmpInst::ICMP_NE:
2662 case ICmpInst::ICMP_ULT:
2663 case ICmpInst::ICMP_ULE:
2664 return getTrue(ITy);
2668 // icmp pred X, (urem Y, X)
2669 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2670 bool KnownNonNegative, KnownNegative;
2674 case ICmpInst::ICMP_SGT:
2675 case ICmpInst::ICMP_SGE:
2676 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2678 if (!KnownNonNegative)
2681 case ICmpInst::ICMP_NE:
2682 case ICmpInst::ICMP_UGT:
2683 case ICmpInst::ICMP_UGE:
2684 return getTrue(ITy);
2685 case ICmpInst::ICMP_SLT:
2686 case ICmpInst::ICMP_SLE:
2687 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2689 if (!KnownNonNegative)
2692 case ICmpInst::ICMP_EQ:
2693 case ICmpInst::ICMP_ULT:
2694 case ICmpInst::ICMP_ULE:
2695 return getFalse(ITy);
2700 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2701 // icmp pred (X /u Y), X
2702 if (Pred == ICmpInst::ICMP_UGT)
2703 return getFalse(ITy);
2704 if (Pred == ICmpInst::ICMP_ULE)
2705 return getTrue(ITy);
2712 // where CI2 is a power of 2 and CI isn't
2713 if (auto *CI = dyn_cast<ConstantInt>(RHS)) {
2714 const APInt *CI2Val, *CIVal = &CI->getValue();
2715 if (LBO && match(LBO, m_Shl(m_APInt(CI2Val), m_Value())) &&
2716 CI2Val->isPowerOf2()) {
2717 if (!CIVal->isPowerOf2()) {
2718 // CI2 << X can equal zero in some circumstances,
2719 // this simplification is unsafe if CI is zero.
2721 // We know it is safe if:
2722 // - The shift is nsw, we can't shift out the one bit.
2723 // - The shift is nuw, we can't shift out the one bit.
2726 if (LBO->hasNoSignedWrap() || LBO->hasNoUnsignedWrap() ||
2727 *CI2Val == 1 || !CI->isZero()) {
2728 if (Pred == ICmpInst::ICMP_EQ)
2729 return ConstantInt::getFalse(RHS->getContext());
2730 if (Pred == ICmpInst::ICMP_NE)
2731 return ConstantInt::getTrue(RHS->getContext());
2734 if (CIVal->isSignBit() && *CI2Val == 1) {
2735 if (Pred == ICmpInst::ICMP_UGT)
2736 return ConstantInt::getFalse(RHS->getContext());
2737 if (Pred == ICmpInst::ICMP_ULE)
2738 return ConstantInt::getTrue(RHS->getContext());
2743 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2744 LBO->getOperand(1) == RBO->getOperand(1)) {
2745 switch (LBO->getOpcode()) {
2747 case Instruction::UDiv:
2748 case Instruction::LShr:
2749 if (ICmpInst::isSigned(Pred))
2752 case Instruction::SDiv:
2753 case Instruction::AShr:
2754 if (!LBO->isExact() || !RBO->isExact())
2756 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2757 RBO->getOperand(0), Q, MaxRecurse-1))
2760 case Instruction::Shl: {
2761 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2762 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2765 if (!NSW && ICmpInst::isSigned(Pred))
2767 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2768 RBO->getOperand(0), Q, MaxRecurse-1))
2775 // Simplify comparisons involving max/min.
2777 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2778 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2780 // Signed variants on "max(a,b)>=a -> true".
2781 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2782 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2783 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2784 // We analyze this as smax(A, B) pred A.
2786 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2787 (A == LHS || B == LHS)) {
2788 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2789 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2790 // We analyze this as smax(A, B) swapped-pred A.
2791 P = CmpInst::getSwappedPredicate(Pred);
2792 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2793 (A == RHS || B == RHS)) {
2794 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2795 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2796 // We analyze this as smax(-A, -B) swapped-pred -A.
2797 // Note that we do not need to actually form -A or -B thanks to EqP.
2798 P = CmpInst::getSwappedPredicate(Pred);
2799 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2800 (A == LHS || B == LHS)) {
2801 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2802 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2803 // We analyze this as smax(-A, -B) pred -A.
2804 // Note that we do not need to actually form -A or -B thanks to EqP.
2807 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2808 // Cases correspond to "max(A, B) p A".
2812 case CmpInst::ICMP_EQ:
2813 case CmpInst::ICMP_SLE:
2814 // Equivalent to "A EqP B". This may be the same as the condition tested
2815 // in the max/min; if so, we can just return that.
2816 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2818 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2820 // Otherwise, see if "A EqP B" simplifies.
2822 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2825 case CmpInst::ICMP_NE:
2826 case CmpInst::ICMP_SGT: {
2827 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2828 // Equivalent to "A InvEqP B". This may be the same as the condition
2829 // tested in the max/min; if so, we can just return that.
2830 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2832 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2834 // Otherwise, see if "A InvEqP B" simplifies.
2836 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2840 case CmpInst::ICMP_SGE:
2842 return getTrue(ITy);
2843 case CmpInst::ICMP_SLT:
2845 return getFalse(ITy);
2849 // Unsigned variants on "max(a,b)>=a -> true".
2850 P = CmpInst::BAD_ICMP_PREDICATE;
2851 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2852 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2853 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2854 // We analyze this as umax(A, B) pred A.
2856 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2857 (A == LHS || B == LHS)) {
2858 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2859 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2860 // We analyze this as umax(A, B) swapped-pred A.
2861 P = CmpInst::getSwappedPredicate(Pred);
2862 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2863 (A == RHS || B == RHS)) {
2864 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2865 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2866 // We analyze this as umax(-A, -B) swapped-pred -A.
2867 // Note that we do not need to actually form -A or -B thanks to EqP.
2868 P = CmpInst::getSwappedPredicate(Pred);
2869 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2870 (A == LHS || B == LHS)) {
2871 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2872 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2873 // We analyze this as umax(-A, -B) pred -A.
2874 // Note that we do not need to actually form -A or -B thanks to EqP.
2877 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2878 // Cases correspond to "max(A, B) p A".
2882 case CmpInst::ICMP_EQ:
2883 case CmpInst::ICMP_ULE:
2884 // Equivalent to "A EqP B". This may be the same as the condition tested
2885 // in the max/min; if so, we can just return that.
2886 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2888 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2890 // Otherwise, see if "A EqP B" simplifies.
2892 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2895 case CmpInst::ICMP_NE:
2896 case CmpInst::ICMP_UGT: {
2897 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2898 // Equivalent to "A InvEqP B". This may be the same as the condition
2899 // tested in the max/min; if so, we can just return that.
2900 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2902 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2904 // Otherwise, see if "A InvEqP B" simplifies.
2906 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2910 case CmpInst::ICMP_UGE:
2912 return getTrue(ITy);
2913 case CmpInst::ICMP_ULT:
2915 return getFalse(ITy);
2919 // Variants on "max(x,y) >= min(x,z)".
2921 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2922 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2923 (A == C || A == D || B == C || B == D)) {
2924 // max(x, ?) pred min(x, ?).
2925 if (Pred == CmpInst::ICMP_SGE)
2927 return getTrue(ITy);
2928 if (Pred == CmpInst::ICMP_SLT)
2930 return getFalse(ITy);
2931 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2932 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2933 (A == C || A == D || B == C || B == D)) {
2934 // min(x, ?) pred max(x, ?).
2935 if (Pred == CmpInst::ICMP_SLE)
2937 return getTrue(ITy);
2938 if (Pred == CmpInst::ICMP_SGT)
2940 return getFalse(ITy);
2941 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2942 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2943 (A == C || A == D || B == C || B == D)) {
2944 // max(x, ?) pred min(x, ?).
2945 if (Pred == CmpInst::ICMP_UGE)
2947 return getTrue(ITy);
2948 if (Pred == CmpInst::ICMP_ULT)
2950 return getFalse(ITy);
2951 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2952 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2953 (A == C || A == D || B == C || B == D)) {
2954 // min(x, ?) pred max(x, ?).
2955 if (Pred == CmpInst::ICMP_ULE)
2957 return getTrue(ITy);
2958 if (Pred == CmpInst::ICMP_UGT)
2960 return getFalse(ITy);
2963 // Simplify comparisons of related pointers using a powerful, recursive
2964 // GEP-walk when we have target data available..
2965 if (LHS->getType()->isPointerTy())
2966 if (Constant *C = computePointerICmp(Q.DL, Q.TLI, Pred, LHS, RHS))
2969 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
2970 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
2971 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
2972 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
2973 (ICmpInst::isEquality(Pred) ||
2974 (GLHS->isInBounds() && GRHS->isInBounds() &&
2975 Pred == ICmpInst::getSignedPredicate(Pred)))) {
2976 // The bases are equal and the indices are constant. Build a constant
2977 // expression GEP with the same indices and a null base pointer to see
2978 // what constant folding can make out of it.
2979 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
2980 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
2981 Constant *NewLHS = ConstantExpr::getGetElementPtr(
2982 GLHS->getSourceElementType(), Null, IndicesLHS);
2984 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
2985 Constant *NewRHS = ConstantExpr::getGetElementPtr(
2986 GLHS->getSourceElementType(), Null, IndicesRHS);
2987 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
2992 // If a bit is known to be zero for A and known to be one for B,
2993 // then A and B cannot be equal.
2994 if (ICmpInst::isEquality(Pred)) {
2995 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2996 uint32_t BitWidth = CI->getBitWidth();
2997 APInt LHSKnownZero(BitWidth, 0);
2998 APInt LHSKnownOne(BitWidth, 0);
2999 computeKnownBits(LHS, LHSKnownZero, LHSKnownOne, Q.DL, /*Depth=*/0, Q.AC,
3001 const APInt &RHSVal = CI->getValue();
3002 if (((LHSKnownZero & RHSVal) != 0) || ((LHSKnownOne & ~RHSVal) != 0))
3003 return Pred == ICmpInst::ICMP_EQ
3004 ? ConstantInt::getFalse(CI->getContext())
3005 : ConstantInt::getTrue(CI->getContext());
3009 // If the comparison is with the result of a select instruction, check whether
3010 // comparing with either branch of the select always yields the same value.
3011 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3012 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3015 // If the comparison is with the result of a phi instruction, check whether
3016 // doing the compare with each incoming phi value yields a common result.
3017 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3018 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3024 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3025 const DataLayout &DL,
3026 const TargetLibraryInfo *TLI,
3027 const DominatorTree *DT, AssumptionCache *AC,
3028 Instruction *CxtI) {
3029 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
3033 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
3034 /// fold the result. If not, this returns null.
3035 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3036 const Query &Q, unsigned MaxRecurse) {
3037 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3038 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
3040 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3041 if (Constant *CRHS = dyn_cast<Constant>(RHS))
3042 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3044 // If we have a constant, make sure it is on the RHS.
3045 std::swap(LHS, RHS);
3046 Pred = CmpInst::getSwappedPredicate(Pred);
3049 // Fold trivial predicates.
3050 if (Pred == FCmpInst::FCMP_FALSE)
3051 return ConstantInt::get(GetCompareTy(LHS), 0);
3052 if (Pred == FCmpInst::FCMP_TRUE)
3053 return ConstantInt::get(GetCompareTy(LHS), 1);
3055 // fcmp pred x, undef and fcmp pred undef, x
3056 // fold to true if unordered, false if ordered
3057 if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS)) {
3058 // Choosing NaN for the undef will always make unordered comparison succeed
3059 // and ordered comparison fail.
3060 return ConstantInt::get(GetCompareTy(LHS), CmpInst::isUnordered(Pred));
3063 // fcmp x,x -> true/false. Not all compares are foldable.
3065 if (CmpInst::isTrueWhenEqual(Pred))
3066 return ConstantInt::get(GetCompareTy(LHS), 1);
3067 if (CmpInst::isFalseWhenEqual(Pred))
3068 return ConstantInt::get(GetCompareTy(LHS), 0);
3071 // Handle fcmp with constant RHS
3072 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
3073 // If the constant is a nan, see if we can fold the comparison based on it.
3074 if (CFP->getValueAPF().isNaN()) {
3075 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
3076 return ConstantInt::getFalse(CFP->getContext());
3077 assert(FCmpInst::isUnordered(Pred) &&
3078 "Comparison must be either ordered or unordered!");
3079 // True if unordered.
3080 return ConstantInt::getTrue(CFP->getContext());
3082 // Check whether the constant is an infinity.
3083 if (CFP->getValueAPF().isInfinity()) {
3084 if (CFP->getValueAPF().isNegative()) {
3086 case FCmpInst::FCMP_OLT:
3087 // No value is ordered and less than negative infinity.
3088 return ConstantInt::getFalse(CFP->getContext());
3089 case FCmpInst::FCMP_UGE:
3090 // All values are unordered with or at least negative infinity.
3091 return ConstantInt::getTrue(CFP->getContext());
3097 case FCmpInst::FCMP_OGT:
3098 // No value is ordered and greater than infinity.
3099 return ConstantInt::getFalse(CFP->getContext());
3100 case FCmpInst::FCMP_ULE:
3101 // All values are unordered with and at most infinity.
3102 return ConstantInt::getTrue(CFP->getContext());
3108 if (CFP->getValueAPF().isZero()) {
3110 case FCmpInst::FCMP_UGE:
3111 if (CannotBeOrderedLessThanZero(LHS))
3112 return ConstantInt::getTrue(CFP->getContext());
3114 case FCmpInst::FCMP_OLT:
3116 if (CannotBeOrderedLessThanZero(LHS))
3117 return ConstantInt::getFalse(CFP->getContext());
3125 // If the comparison is with the result of a select instruction, check whether
3126 // comparing with either branch of the select always yields the same value.
3127 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3128 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3131 // If the comparison is with the result of a phi instruction, check whether
3132 // doing the compare with each incoming phi value yields a common result.
3133 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3134 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3140 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3141 const DataLayout &DL,
3142 const TargetLibraryInfo *TLI,
3143 const DominatorTree *DT, AssumptionCache *AC,
3144 const Instruction *CxtI) {
3145 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
3149 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
3150 /// the result. If not, this returns null.
3151 static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
3152 Value *FalseVal, const Query &Q,
3153 unsigned MaxRecurse) {
3154 // select true, X, Y -> X
3155 // select false, X, Y -> Y
3156 if (Constant *CB = dyn_cast<Constant>(CondVal)) {
3157 if (CB->isAllOnesValue())
3159 if (CB->isNullValue())
3163 // select C, X, X -> X
3164 if (TrueVal == FalseVal)
3167 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
3168 if (isa<Constant>(TrueVal))
3172 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
3174 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
3177 const auto *ICI = dyn_cast<ICmpInst>(CondVal);
3178 unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits();
3179 if (ICI && BitWidth) {
3180 ICmpInst::Predicate Pred = ICI->getPredicate();
3181 APInt MinSignedValue = APInt::getSignBit(BitWidth);
3185 bool IsBitTest = false;
3186 if (ICmpInst::isEquality(Pred) &&
3187 match(ICI->getOperand(0), m_And(m_Value(X), m_APInt(Y))) &&
3188 match(ICI->getOperand(1), m_Zero())) {
3190 TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
3191 } else if (Pred == ICmpInst::ICMP_SLT &&
3192 match(ICI->getOperand(1), m_Zero())) {
3193 X = ICI->getOperand(0);
3194 Y = &MinSignedValue;
3196 TrueWhenUnset = false;
3197 } else if (Pred == ICmpInst::ICMP_SGT &&
3198 match(ICI->getOperand(1), m_AllOnes())) {
3199 X = ICI->getOperand(0);
3200 Y = &MinSignedValue;
3202 TrueWhenUnset = true;
3206 // (X & Y) == 0 ? X & ~Y : X --> X
3207 // (X & Y) != 0 ? X & ~Y : X --> X & ~Y
3208 if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) &&
3210 return TrueWhenUnset ? FalseVal : TrueVal;
3211 // (X & Y) == 0 ? X : X & ~Y --> X & ~Y
3212 // (X & Y) != 0 ? X : X & ~Y --> X
3213 if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) &&
3215 return TrueWhenUnset ? FalseVal : TrueVal;
3217 if (Y->isPowerOf2()) {
3218 // (X & Y) == 0 ? X | Y : X --> X | Y
3219 // (X & Y) != 0 ? X | Y : X --> X
3220 if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) &&
3222 return TrueWhenUnset ? TrueVal : FalseVal;
3223 // (X & Y) == 0 ? X : X | Y --> X
3224 // (X & Y) != 0 ? X : X | Y --> X | Y
3225 if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) &&
3227 return TrueWhenUnset ? TrueVal : FalseVal;
3235 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3236 const DataLayout &DL,
3237 const TargetLibraryInfo *TLI,
3238 const DominatorTree *DT, AssumptionCache *AC,
3239 const Instruction *CxtI) {
3240 return ::SimplifySelectInst(Cond, TrueVal, FalseVal,
3241 Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
3244 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
3245 /// fold the result. If not, this returns null.
3246 static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
3247 const Query &Q, unsigned) {
3248 // The type of the GEP pointer operand.
3250 cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace();
3252 // getelementptr P -> P.
3253 if (Ops.size() == 1)
3256 // Compute the (pointer) type returned by the GEP instruction.
3257 Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1));
3258 Type *GEPTy = PointerType::get(LastType, AS);
3259 if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
3260 GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3262 if (isa<UndefValue>(Ops[0]))
3263 return UndefValue::get(GEPTy);
3265 if (Ops.size() == 2) {
3266 // getelementptr P, 0 -> P.
3267 if (match(Ops[1], m_Zero()))
3271 if (Ty->isSized()) {
3274 uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty);
3275 // getelementptr P, N -> P if P points to a type of zero size.
3276 if (TyAllocSize == 0)
3279 // The following transforms are only safe if the ptrtoint cast
3280 // doesn't truncate the pointers.
3281 if (Ops[1]->getType()->getScalarSizeInBits() ==
3282 Q.DL.getPointerSizeInBits(AS)) {
3283 auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * {
3284 if (match(P, m_Zero()))
3285 return Constant::getNullValue(GEPTy);
3287 if (match(P, m_PtrToInt(m_Value(Temp))))
3288 if (Temp->getType() == GEPTy)
3293 // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
3294 if (TyAllocSize == 1 &&
3295 match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0])))))
3296 if (Value *R = PtrToIntOrZero(P))
3299 // getelementptr V, (ashr (sub P, V), C) -> Q
3300 // if P points to a type of size 1 << C.
3302 m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3303 m_ConstantInt(C))) &&
3304 TyAllocSize == 1ULL << C)
3305 if (Value *R = PtrToIntOrZero(P))
3308 // getelementptr V, (sdiv (sub P, V), C) -> Q
3309 // if P points to a type of size C.
3311 m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3312 m_SpecificInt(TyAllocSize))))
3313 if (Value *R = PtrToIntOrZero(P))
3319 // Check to see if this is constant foldable.
3320 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3321 if (!isa<Constant>(Ops[i]))
3324 return ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]),
3328 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const DataLayout &DL,
3329 const TargetLibraryInfo *TLI,
3330 const DominatorTree *DT, AssumptionCache *AC,
3331 const Instruction *CxtI) {
3332 return ::SimplifyGEPInst(
3333 cast<PointerType>(Ops[0]->getType()->getScalarType())->getElementType(),
3334 Ops, Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
3337 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
3338 /// can fold the result. If not, this returns null.
3339 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
3340 ArrayRef<unsigned> Idxs, const Query &Q,
3342 if (Constant *CAgg = dyn_cast<Constant>(Agg))
3343 if (Constant *CVal = dyn_cast<Constant>(Val))
3344 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
3346 // insertvalue x, undef, n -> x
3347 if (match(Val, m_Undef()))
3350 // insertvalue x, (extractvalue y, n), n
3351 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
3352 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
3353 EV->getIndices() == Idxs) {
3354 // insertvalue undef, (extractvalue y, n), n -> y
3355 if (match(Agg, m_Undef()))
3356 return EV->getAggregateOperand();
3358 // insertvalue y, (extractvalue y, n), n -> y
3359 if (Agg == EV->getAggregateOperand())
3366 Value *llvm::SimplifyInsertValueInst(
3367 Value *Agg, Value *Val, ArrayRef<unsigned> Idxs, const DataLayout &DL,
3368 const TargetLibraryInfo *TLI, const DominatorTree *DT, AssumptionCache *AC,
3369 const Instruction *CxtI) {
3370 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query(DL, TLI, DT, AC, CxtI),
3374 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
3375 static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
3376 // If all of the PHI's incoming values are the same then replace the PHI node
3377 // with the common value.
3378 Value *CommonValue = nullptr;
3379 bool HasUndefInput = false;
3380 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
3381 Value *Incoming = PN->getIncomingValue(i);
3382 // If the incoming value is the phi node itself, it can safely be skipped.
3383 if (Incoming == PN) continue;
3384 if (isa<UndefValue>(Incoming)) {
3385 // Remember that we saw an undef value, but otherwise ignore them.
3386 HasUndefInput = true;
3389 if (CommonValue && Incoming != CommonValue)
3390 return nullptr; // Not the same, bail out.
3391 CommonValue = Incoming;
3394 // If CommonValue is null then all of the incoming values were either undef or
3395 // equal to the phi node itself.
3397 return UndefValue::get(PN->getType());
3399 // If we have a PHI node like phi(X, undef, X), where X is defined by some
3400 // instruction, we cannot return X as the result of the PHI node unless it
3401 // dominates the PHI block.
3403 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr;
3408 static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) {
3409 if (Constant *C = dyn_cast<Constant>(Op))
3410 return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.DL, Q.TLI);
3415 Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const DataLayout &DL,
3416 const TargetLibraryInfo *TLI,
3417 const DominatorTree *DT, AssumptionCache *AC,
3418 const Instruction *CxtI) {
3419 return ::SimplifyTruncInst(Op, Ty, Query(DL, TLI, DT, AC, CxtI),
3423 //=== Helper functions for higher up the class hierarchy.
3425 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
3426 /// fold the result. If not, this returns null.
3427 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
3428 const Query &Q, unsigned MaxRecurse) {
3430 case Instruction::Add:
3431 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3433 case Instruction::FAdd:
3434 return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3436 case Instruction::Sub:
3437 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3439 case Instruction::FSub:
3440 return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3442 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
3443 case Instruction::FMul:
3444 return SimplifyFMulInst (LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3445 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
3446 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
3447 case Instruction::FDiv:
3448 return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3449 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
3450 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
3451 case Instruction::FRem:
3452 return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3453 case Instruction::Shl:
3454 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3456 case Instruction::LShr:
3457 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
3458 case Instruction::AShr:
3459 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
3460 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
3461 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
3462 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
3464 if (Constant *CLHS = dyn_cast<Constant>(LHS))
3465 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
3466 Constant *COps[] = {CLHS, CRHS};
3467 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.DL,
3471 // If the operation is associative, try some generic simplifications.
3472 if (Instruction::isAssociative(Opcode))
3473 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
3476 // If the operation is with the result of a select instruction check whether
3477 // operating on either branch of the select always yields the same value.
3478 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3479 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
3482 // If the operation is with the result of a phi instruction, check whether
3483 // operating on all incoming values of the phi always yields the same value.
3484 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3485 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
3492 /// SimplifyFPBinOp - Given operands for a BinaryOperator, see if we can
3493 /// fold the result. If not, this returns null.
3494 /// In contrast to SimplifyBinOp, try to use FastMathFlag when folding the
3495 /// result. In case we don't need FastMathFlags, simply fall to SimplifyBinOp.
3496 static Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
3497 const FastMathFlags &FMF, const Query &Q,
3498 unsigned MaxRecurse) {
3500 case Instruction::FAdd:
3501 return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse);
3502 case Instruction::FSub:
3503 return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse);
3504 case Instruction::FMul:
3505 return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse);
3507 return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
3511 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
3512 const DataLayout &DL, const TargetLibraryInfo *TLI,
3513 const DominatorTree *DT, AssumptionCache *AC,
3514 const Instruction *CxtI) {
3515 return ::SimplifyBinOp(Opcode, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
3519 Value *llvm::SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
3520 const FastMathFlags &FMF, const DataLayout &DL,
3521 const TargetLibraryInfo *TLI,
3522 const DominatorTree *DT, AssumptionCache *AC,
3523 const Instruction *CxtI) {
3524 return ::SimplifyFPBinOp(Opcode, LHS, RHS, FMF, Query(DL, TLI, DT, AC, CxtI),
3528 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
3529 /// fold the result.
3530 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3531 const Query &Q, unsigned MaxRecurse) {
3532 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
3533 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
3534 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
3537 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3538 const DataLayout &DL, const TargetLibraryInfo *TLI,
3539 const DominatorTree *DT, AssumptionCache *AC,
3540 const Instruction *CxtI) {
3541 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
3545 static bool IsIdempotent(Intrinsic::ID ID) {
3547 default: return false;
3549 // Unary idempotent: f(f(x)) = f(x)
3550 case Intrinsic::fabs:
3551 case Intrinsic::floor:
3552 case Intrinsic::ceil:
3553 case Intrinsic::trunc:
3554 case Intrinsic::rint:
3555 case Intrinsic::nearbyint:
3556 case Intrinsic::round:
3561 template <typename IterTy>
3562 static Value *SimplifyIntrinsic(Intrinsic::ID IID, IterTy ArgBegin, IterTy ArgEnd,
3563 const Query &Q, unsigned MaxRecurse) {
3564 // Perform idempotent optimizations
3565 if (!IsIdempotent(IID))
3569 if (std::distance(ArgBegin, ArgEnd) == 1)
3570 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin))
3571 if (II->getIntrinsicID() == IID)
3577 template <typename IterTy>
3578 static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd,
3579 const Query &Q, unsigned MaxRecurse) {
3580 Type *Ty = V->getType();
3581 if (PointerType *PTy = dyn_cast<PointerType>(Ty))
3582 Ty = PTy->getElementType();
3583 FunctionType *FTy = cast<FunctionType>(Ty);
3585 // call undef -> undef
3586 if (isa<UndefValue>(V))
3587 return UndefValue::get(FTy->getReturnType());
3589 Function *F = dyn_cast<Function>(V);
3593 if (unsigned IID = F->getIntrinsicID())
3595 SimplifyIntrinsic((Intrinsic::ID) IID, ArgBegin, ArgEnd, Q, MaxRecurse))
3598 if (!canConstantFoldCallTo(F))
3601 SmallVector<Constant *, 4> ConstantArgs;
3602 ConstantArgs.reserve(ArgEnd - ArgBegin);
3603 for (IterTy I = ArgBegin, E = ArgEnd; I != E; ++I) {
3604 Constant *C = dyn_cast<Constant>(*I);
3607 ConstantArgs.push_back(C);
3610 return ConstantFoldCall(F, ConstantArgs, Q.TLI);
3613 Value *llvm::SimplifyCall(Value *V, User::op_iterator ArgBegin,
3614 User::op_iterator ArgEnd, const DataLayout &DL,
3615 const TargetLibraryInfo *TLI, const DominatorTree *DT,
3616 AssumptionCache *AC, const Instruction *CxtI) {
3617 return ::SimplifyCall(V, ArgBegin, ArgEnd, Query(DL, TLI, DT, AC, CxtI),
3621 Value *llvm::SimplifyCall(Value *V, ArrayRef<Value *> Args,
3622 const DataLayout &DL, const TargetLibraryInfo *TLI,
3623 const DominatorTree *DT, AssumptionCache *AC,
3624 const Instruction *CxtI) {
3625 return ::SimplifyCall(V, Args.begin(), Args.end(),
3626 Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
3629 /// SimplifyInstruction - See if we can compute a simplified version of this
3630 /// instruction. If not, this returns null.
3631 Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout &DL,
3632 const TargetLibraryInfo *TLI,
3633 const DominatorTree *DT, AssumptionCache *AC) {
3636 switch (I->getOpcode()) {
3638 Result = ConstantFoldInstruction(I, DL, TLI);
3640 case Instruction::FAdd:
3641 Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
3642 I->getFastMathFlags(), DL, TLI, DT, AC, I);
3644 case Instruction::Add:
3645 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
3646 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3647 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
3650 case Instruction::FSub:
3651 Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
3652 I->getFastMathFlags(), DL, TLI, DT, AC, I);
3654 case Instruction::Sub:
3655 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
3656 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3657 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
3660 case Instruction::FMul:
3661 Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1),
3662 I->getFastMathFlags(), DL, TLI, DT, AC, I);
3664 case Instruction::Mul:
3666 SimplifyMulInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
3668 case Instruction::SDiv:
3669 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3672 case Instruction::UDiv:
3673 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3676 case Instruction::FDiv:
3677 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1),
3678 I->getFastMathFlags(), DL, TLI, DT, AC, I);
3680 case Instruction::SRem:
3681 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3684 case Instruction::URem:
3685 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3688 case Instruction::FRem:
3689 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1),
3690 I->getFastMathFlags(), DL, TLI, DT, AC, I);
3692 case Instruction::Shl:
3693 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
3694 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3695 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
3698 case Instruction::LShr:
3699 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
3700 cast<BinaryOperator>(I)->isExact(), DL, TLI, DT,
3703 case Instruction::AShr:
3704 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
3705 cast<BinaryOperator>(I)->isExact(), DL, TLI, DT,
3708 case Instruction::And:
3710 SimplifyAndInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
3712 case Instruction::Or:
3714 SimplifyOrInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
3716 case Instruction::Xor:
3718 SimplifyXorInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
3720 case Instruction::ICmp:
3722 SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), I->getOperand(0),
3723 I->getOperand(1), DL, TLI, DT, AC, I);
3725 case Instruction::FCmp:
3727 SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0),
3728 I->getOperand(1), DL, TLI, DT, AC, I);
3730 case Instruction::Select:
3731 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
3732 I->getOperand(2), DL, TLI, DT, AC, I);
3734 case Instruction::GetElementPtr: {
3735 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
3736 Result = SimplifyGEPInst(Ops, DL, TLI, DT, AC, I);
3739 case Instruction::InsertValue: {
3740 InsertValueInst *IV = cast<InsertValueInst>(I);
3741 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
3742 IV->getInsertedValueOperand(),
3743 IV->getIndices(), DL, TLI, DT, AC, I);
3746 case Instruction::PHI:
3747 Result = SimplifyPHINode(cast<PHINode>(I), Query(DL, TLI, DT, AC, I));
3749 case Instruction::Call: {
3750 CallSite CS(cast<CallInst>(I));
3751 Result = SimplifyCall(CS.getCalledValue(), CS.arg_begin(), CS.arg_end(), DL,
3755 case Instruction::Trunc:
3757 SimplifyTruncInst(I->getOperand(0), I->getType(), DL, TLI, DT, AC, I);
3761 /// If called on unreachable code, the above logic may report that the
3762 /// instruction simplified to itself. Make life easier for users by
3763 /// detecting that case here, returning a safe value instead.
3764 return Result == I ? UndefValue::get(I->getType()) : Result;
3767 /// \brief Implementation of recursive simplification through an instructions
3770 /// This is the common implementation of the recursive simplification routines.
3771 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
3772 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
3773 /// instructions to process and attempt to simplify it using
3774 /// InstructionSimplify.
3776 /// This routine returns 'true' only when *it* simplifies something. The passed
3777 /// in simplified value does not count toward this.
3778 static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
3779 const TargetLibraryInfo *TLI,
3780 const DominatorTree *DT,
3781 AssumptionCache *AC) {
3782 bool Simplified = false;
3783 SmallSetVector<Instruction *, 8> Worklist;
3784 const DataLayout &DL = I->getModule()->getDataLayout();
3786 // If we have an explicit value to collapse to, do that round of the
3787 // simplification loop by hand initially.
3789 for (User *U : I->users())
3791 Worklist.insert(cast<Instruction>(U));
3793 // Replace the instruction with its simplified value.
3794 I->replaceAllUsesWith(SimpleV);
3796 // Gracefully handle edge cases where the instruction is not wired into any
3799 I->eraseFromParent();
3804 // Note that we must test the size on each iteration, the worklist can grow.
3805 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
3808 // See if this instruction simplifies.
3809 SimpleV = SimplifyInstruction(I, DL, TLI, DT, AC);
3815 // Stash away all the uses of the old instruction so we can check them for
3816 // recursive simplifications after a RAUW. This is cheaper than checking all
3817 // uses of To on the recursive step in most cases.
3818 for (User *U : I->users())
3819 Worklist.insert(cast<Instruction>(U));
3821 // Replace the instruction with its simplified value.
3822 I->replaceAllUsesWith(SimpleV);
3824 // Gracefully handle edge cases where the instruction is not wired into any
3827 I->eraseFromParent();
3832 bool llvm::recursivelySimplifyInstruction(Instruction *I,
3833 const TargetLibraryInfo *TLI,
3834 const DominatorTree *DT,
3835 AssumptionCache *AC) {
3836 return replaceAndRecursivelySimplifyImpl(I, nullptr, TLI, DT, AC);
3839 bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
3840 const TargetLibraryInfo *TLI,
3841 const DominatorTree *DT,
3842 AssumptionCache *AC) {
3843 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
3844 assert(SimpleV && "Must provide a simplified value.");
3845 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC);