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/ConstantFolding.h"
24 #include "llvm/Analysis/MemoryBuiltins.h"
25 #include "llvm/Analysis/ValueTracking.h"
26 #include "llvm/IR/ConstantRange.h"
27 #include "llvm/IR/DataLayout.h"
28 #include "llvm/IR/Dominators.h"
29 #include "llvm/IR/GetElementPtrTypeIterator.h"
30 #include "llvm/IR/GlobalAlias.h"
31 #include "llvm/IR/Operator.h"
32 #include "llvm/IR/PatternMatch.h"
33 #include "llvm/IR/ValueHandle.h"
35 using namespace llvm::PatternMatch;
37 #define DEBUG_TYPE "instsimplify"
39 enum { RecursionLimit = 3 };
41 STATISTIC(NumExpand, "Number of expansions");
42 STATISTIC(NumReassoc, "Number of reassociations");
47 const TargetLibraryInfo *TLI;
48 const DominatorTree *DT;
49 AssumptionTracker *AT;
50 const Instruction *CxtI;
52 Query(const DataLayout *DL, const TargetLibraryInfo *tli,
53 const DominatorTree *dt, AssumptionTracker *at = nullptr,
54 const Instruction *cxti = nullptr)
55 : DL(DL), TLI(tli), DT(dt), AT(at), CxtI(cxti) {}
57 } // end anonymous namespace
59 static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
60 static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
62 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
64 static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
65 static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
66 static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned);
68 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
69 /// a vector with every element false, as appropriate for the type.
70 static Constant *getFalse(Type *Ty) {
71 assert(Ty->getScalarType()->isIntegerTy(1) &&
72 "Expected i1 type or a vector of i1!");
73 return Constant::getNullValue(Ty);
76 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
77 /// a vector with every element true, as appropriate for the type.
78 static Constant *getTrue(Type *Ty) {
79 assert(Ty->getScalarType()->isIntegerTy(1) &&
80 "Expected i1 type or a vector of i1!");
81 return Constant::getAllOnesValue(Ty);
84 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
85 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
87 CmpInst *Cmp = dyn_cast<CmpInst>(V);
90 CmpInst::Predicate CPred = Cmp->getPredicate();
91 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
92 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
94 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
98 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
99 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
100 Instruction *I = dyn_cast<Instruction>(V);
102 // Arguments and constants dominate all instructions.
105 // If we are processing instructions (and/or basic blocks) that have not been
106 // fully added to a function, the parent nodes may still be null. Simply
107 // return the conservative answer in these cases.
108 if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
111 // If we have a DominatorTree then do a precise test.
113 if (!DT->isReachableFromEntry(P->getParent()))
115 if (!DT->isReachableFromEntry(I->getParent()))
117 return DT->dominates(I, P);
120 // Otherwise, if the instruction is in the entry block, and is not an invoke,
121 // then it obviously dominates all phi nodes.
122 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
129 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
130 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
131 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
132 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
133 /// Returns the simplified value, or null if no simplification was performed.
134 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
135 unsigned OpcToExpand, const Query &Q,
136 unsigned MaxRecurse) {
137 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
138 // Recursion is always used, so bail out at once if we already hit the limit.
142 // Check whether the expression has the form "(A op' B) op C".
143 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
144 if (Op0->getOpcode() == OpcodeToExpand) {
145 // It does! Try turning it into "(A op C) op' (B op C)".
146 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
147 // Do "A op C" and "B op C" both simplify?
148 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
149 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
150 // They do! Return "L op' R" if it simplifies or is already available.
151 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
152 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
153 && L == B && R == A)) {
157 // Otherwise return "L op' R" if it simplifies.
158 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
165 // Check whether the expression has the form "A op (B op' C)".
166 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
167 if (Op1->getOpcode() == OpcodeToExpand) {
168 // It does! Try turning it into "(A op B) op' (A op C)".
169 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
170 // Do "A op B" and "A op C" both simplify?
171 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
172 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
173 // They do! Return "L op' R" if it simplifies or is already available.
174 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
175 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
176 && L == C && R == B)) {
180 // Otherwise return "L op' R" if it simplifies.
181 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
191 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
192 /// operations. Returns the simpler value, or null if none was found.
193 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
194 const Query &Q, unsigned MaxRecurse) {
195 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
196 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
198 // Recursion is always used, so bail out at once if we already hit the limit.
202 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
203 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
205 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
206 if (Op0 && Op0->getOpcode() == Opcode) {
207 Value *A = Op0->getOperand(0);
208 Value *B = Op0->getOperand(1);
211 // Does "B op C" simplify?
212 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
213 // It does! Return "A op V" if it simplifies or is already available.
214 // If V equals B then "A op V" is just the LHS.
215 if (V == B) return LHS;
216 // Otherwise return "A op V" if it simplifies.
217 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
224 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
225 if (Op1 && Op1->getOpcode() == Opcode) {
227 Value *B = Op1->getOperand(0);
228 Value *C = Op1->getOperand(1);
230 // Does "A op B" simplify?
231 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
232 // It does! Return "V op C" if it simplifies or is already available.
233 // If V equals B then "V op C" is just the RHS.
234 if (V == B) return RHS;
235 // Otherwise return "V op C" if it simplifies.
236 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
243 // The remaining transforms require commutativity as well as associativity.
244 if (!Instruction::isCommutative(Opcode))
247 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
248 if (Op0 && Op0->getOpcode() == Opcode) {
249 Value *A = Op0->getOperand(0);
250 Value *B = Op0->getOperand(1);
253 // Does "C op A" simplify?
254 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
255 // It does! Return "V op B" if it simplifies or is already available.
256 // If V equals A then "V op B" is just the LHS.
257 if (V == A) return LHS;
258 // Otherwise return "V op B" if it simplifies.
259 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
266 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
267 if (Op1 && Op1->getOpcode() == Opcode) {
269 Value *B = Op1->getOperand(0);
270 Value *C = Op1->getOperand(1);
272 // Does "C op A" simplify?
273 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
274 // It does! Return "B op V" if it simplifies or is already available.
275 // If V equals C then "B op V" is just the RHS.
276 if (V == C) return RHS;
277 // Otherwise return "B op V" if it simplifies.
278 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
288 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
289 /// instruction as an operand, try to simplify the binop by seeing whether
290 /// evaluating it on both branches of the select results in the same value.
291 /// Returns the common value if so, otherwise returns null.
292 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
293 const Query &Q, unsigned MaxRecurse) {
294 // Recursion is always used, so bail out at once if we already hit the limit.
299 if (isa<SelectInst>(LHS)) {
300 SI = cast<SelectInst>(LHS);
302 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
303 SI = cast<SelectInst>(RHS);
306 // Evaluate the BinOp on the true and false branches of the select.
310 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
311 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
313 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
314 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
317 // If they simplified to the same value, then return the common value.
318 // If they both failed to simplify then return null.
322 // If one branch simplified to undef, return the other one.
323 if (TV && isa<UndefValue>(TV))
325 if (FV && isa<UndefValue>(FV))
328 // If applying the operation did not change the true and false select values,
329 // then the result of the binop is the select itself.
330 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
333 // If one branch simplified and the other did not, and the simplified
334 // value is equal to the unsimplified one, return the simplified value.
335 // For example, select (cond, X, X & Z) & Z -> X & Z.
336 if ((FV && !TV) || (TV && !FV)) {
337 // Check that the simplified value has the form "X op Y" where "op" is the
338 // same as the original operation.
339 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
340 if (Simplified && Simplified->getOpcode() == Opcode) {
341 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
342 // We already know that "op" is the same as for the simplified value. See
343 // if the operands match too. If so, return the simplified value.
344 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
345 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
346 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
347 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
348 Simplified->getOperand(1) == UnsimplifiedRHS)
350 if (Simplified->isCommutative() &&
351 Simplified->getOperand(1) == UnsimplifiedLHS &&
352 Simplified->getOperand(0) == UnsimplifiedRHS)
360 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
361 /// try to simplify the comparison by seeing whether both branches of the select
362 /// result in the same value. Returns the common value if so, otherwise returns
364 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
365 Value *RHS, const Query &Q,
366 unsigned MaxRecurse) {
367 // Recursion is always used, so bail out at once if we already hit the limit.
371 // Make sure the select is on the LHS.
372 if (!isa<SelectInst>(LHS)) {
374 Pred = CmpInst::getSwappedPredicate(Pred);
376 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
377 SelectInst *SI = cast<SelectInst>(LHS);
378 Value *Cond = SI->getCondition();
379 Value *TV = SI->getTrueValue();
380 Value *FV = SI->getFalseValue();
382 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
383 // Does "cmp TV, RHS" simplify?
384 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
386 // It not only simplified, it simplified to the select condition. Replace
388 TCmp = getTrue(Cond->getType());
390 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
391 // condition then we can replace it with 'true'. Otherwise give up.
392 if (!isSameCompare(Cond, Pred, TV, RHS))
394 TCmp = getTrue(Cond->getType());
397 // Does "cmp FV, RHS" simplify?
398 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
400 // It not only simplified, it simplified to the select condition. Replace
402 FCmp = getFalse(Cond->getType());
404 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
405 // condition then we can replace it with 'false'. Otherwise give up.
406 if (!isSameCompare(Cond, Pred, FV, RHS))
408 FCmp = getFalse(Cond->getType());
411 // If both sides simplified to the same value, then use it as the result of
412 // the original comparison.
416 // The remaining cases only make sense if the select condition has the same
417 // type as the result of the comparison, so bail out if this is not so.
418 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
420 // If the false value simplified to false, then the result of the compare
421 // is equal to "Cond && TCmp". This also catches the case when the false
422 // value simplified to false and the true value to true, returning "Cond".
423 if (match(FCmp, m_Zero()))
424 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
426 // If the true value simplified to true, then the result of the compare
427 // is equal to "Cond || FCmp".
428 if (match(TCmp, m_One()))
429 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
431 // Finally, if the false value simplified to true and the true value to
432 // false, then the result of the compare is equal to "!Cond".
433 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
435 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
442 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
443 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
444 /// it on the incoming phi values yields the same result for every value. If so
445 /// returns the common value, otherwise returns null.
446 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
447 const Query &Q, unsigned MaxRecurse) {
448 // Recursion is always used, so bail out at once if we already hit the limit.
453 if (isa<PHINode>(LHS)) {
454 PI = cast<PHINode>(LHS);
455 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
456 if (!ValueDominatesPHI(RHS, PI, Q.DT))
459 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
460 PI = cast<PHINode>(RHS);
461 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
462 if (!ValueDominatesPHI(LHS, PI, Q.DT))
466 // Evaluate the BinOp on the incoming phi values.
467 Value *CommonValue = nullptr;
468 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
469 Value *Incoming = PI->getIncomingValue(i);
470 // If the incoming value is the phi node itself, it can safely be skipped.
471 if (Incoming == PI) continue;
472 Value *V = PI == LHS ?
473 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
474 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
475 // If the operation failed to simplify, or simplified to a different value
476 // to previously, then give up.
477 if (!V || (CommonValue && V != CommonValue))
485 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
486 /// try to simplify the comparison by seeing whether comparing with all of the
487 /// incoming phi values yields the same result every time. If so returns the
488 /// common result, otherwise returns null.
489 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
490 const Query &Q, unsigned MaxRecurse) {
491 // Recursion is always used, so bail out at once if we already hit the limit.
495 // Make sure the phi is on the LHS.
496 if (!isa<PHINode>(LHS)) {
498 Pred = CmpInst::getSwappedPredicate(Pred);
500 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
501 PHINode *PI = cast<PHINode>(LHS);
503 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
504 if (!ValueDominatesPHI(RHS, PI, Q.DT))
507 // Evaluate the BinOp on the incoming phi values.
508 Value *CommonValue = nullptr;
509 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
510 Value *Incoming = PI->getIncomingValue(i);
511 // If the incoming value is the phi node itself, it can safely be skipped.
512 if (Incoming == PI) continue;
513 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
514 // If the operation failed to simplify, or simplified to a different value
515 // to previously, then give up.
516 if (!V || (CommonValue && V != CommonValue))
524 /// SimplifyAddInst - Given operands for an Add, see if we can
525 /// fold the result. If not, this returns null.
526 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
527 const Query &Q, unsigned MaxRecurse) {
528 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
529 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
530 Constant *Ops[] = { CLHS, CRHS };
531 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops,
535 // Canonicalize the constant to the RHS.
539 // X + undef -> undef
540 if (match(Op1, m_Undef()))
544 if (match(Op1, m_Zero()))
551 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
552 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
555 // X + ~X -> -1 since ~X = -X-1
556 if (match(Op0, m_Not(m_Specific(Op1))) ||
557 match(Op1, m_Not(m_Specific(Op0))))
558 return Constant::getAllOnesValue(Op0->getType());
561 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
562 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
565 // Try some generic simplifications for associative operations.
566 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
570 // Threading Add over selects and phi nodes is pointless, so don't bother.
571 // Threading over the select in "A + select(cond, B, C)" means evaluating
572 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
573 // only if B and C are equal. If B and C are equal then (since we assume
574 // that operands have already been simplified) "select(cond, B, C)" should
575 // have been simplified to the common value of B and C already. Analysing
576 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
577 // for threading over phi nodes.
582 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
583 const DataLayout *DL, const TargetLibraryInfo *TLI,
584 const DominatorTree *DT, AssumptionTracker *AT,
585 const Instruction *CxtI) {
586 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW,
587 Query (DL, TLI, DT, AT, CxtI), RecursionLimit);
590 /// \brief Compute the base pointer and cumulative constant offsets for V.
592 /// This strips all constant offsets off of V, leaving it the base pointer, and
593 /// accumulates the total constant offset applied in the returned constant. It
594 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
595 /// no constant offsets applied.
597 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
598 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
600 static Constant *stripAndComputeConstantOffsets(const DataLayout *DL,
602 bool AllowNonInbounds = false) {
603 assert(V->getType()->getScalarType()->isPointerTy());
605 // Without DataLayout, just be conservative for now. Theoretically, more could
606 // be done in this case.
608 return ConstantInt::get(IntegerType::get(V->getContext(), 64), 0);
610 Type *IntPtrTy = DL->getIntPtrType(V->getType())->getScalarType();
611 APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
613 // Even though we don't look through PHI nodes, we could be called on an
614 // instruction in an unreachable block, which may be on a cycle.
615 SmallPtrSet<Value *, 4> Visited;
618 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
619 if ((!AllowNonInbounds && !GEP->isInBounds()) ||
620 !GEP->accumulateConstantOffset(*DL, Offset))
622 V = GEP->getPointerOperand();
623 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
624 V = cast<Operator>(V)->getOperand(0);
625 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
626 if (GA->mayBeOverridden())
628 V = GA->getAliasee();
632 assert(V->getType()->getScalarType()->isPointerTy() &&
633 "Unexpected operand type!");
634 } while (Visited.insert(V).second);
636 Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
637 if (V->getType()->isVectorTy())
638 return ConstantVector::getSplat(V->getType()->getVectorNumElements(),
643 /// \brief Compute the constant difference between two pointer values.
644 /// If the difference is not a constant, returns zero.
645 static Constant *computePointerDifference(const DataLayout *DL,
646 Value *LHS, Value *RHS) {
647 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
648 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
650 // If LHS and RHS are not related via constant offsets to the same base
651 // value, there is nothing we can do here.
655 // Otherwise, the difference of LHS - RHS can be computed as:
657 // = (LHSOffset + Base) - (RHSOffset + Base)
658 // = LHSOffset - RHSOffset
659 return ConstantExpr::getSub(LHSOffset, RHSOffset);
662 /// SimplifySubInst - Given operands for a Sub, see if we can
663 /// fold the result. If not, this returns null.
664 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
665 const Query &Q, unsigned MaxRecurse) {
666 if (Constant *CLHS = dyn_cast<Constant>(Op0))
667 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
668 Constant *Ops[] = { CLHS, CRHS };
669 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
673 // X - undef -> undef
674 // undef - X -> undef
675 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
676 return UndefValue::get(Op0->getType());
679 if (match(Op1, m_Zero()))
684 return Constant::getNullValue(Op0->getType());
686 // 0 - X -> 0 if the sub is NUW.
687 if (isNUW && match(Op0, m_Zero()))
690 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
691 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
692 Value *X = nullptr, *Y = nullptr, *Z = Op1;
693 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
694 // See if "V === Y - Z" simplifies.
695 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
696 // It does! Now see if "X + V" simplifies.
697 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
698 // It does, we successfully reassociated!
702 // See if "V === X - Z" simplifies.
703 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
704 // It does! Now see if "Y + V" simplifies.
705 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
706 // It does, we successfully reassociated!
712 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
713 // For example, X - (X + 1) -> -1
715 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
716 // See if "V === X - Y" simplifies.
717 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
718 // It does! Now see if "V - Z" simplifies.
719 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
720 // It does, we successfully reassociated!
724 // See if "V === X - Z" simplifies.
725 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
726 // It does! Now see if "V - Y" simplifies.
727 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
728 // It does, we successfully reassociated!
734 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
735 // For example, X - (X - Y) -> Y.
737 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
738 // See if "V === Z - X" simplifies.
739 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
740 // It does! Now see if "V + Y" simplifies.
741 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
742 // It does, we successfully reassociated!
747 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
748 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
749 match(Op1, m_Trunc(m_Value(Y))))
750 if (X->getType() == Y->getType())
751 // See if "V === X - Y" simplifies.
752 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
753 // It does! Now see if "trunc V" simplifies.
754 if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1))
755 // It does, return the simplified "trunc V".
758 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
759 if (match(Op0, m_PtrToInt(m_Value(X))) &&
760 match(Op1, m_PtrToInt(m_Value(Y))))
761 if (Constant *Result = computePointerDifference(Q.DL, X, Y))
762 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
765 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
766 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
769 // Threading Sub over selects and phi nodes is pointless, so don't bother.
770 // Threading over the select in "A - select(cond, B, C)" means evaluating
771 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
772 // only if B and C are equal. If B and C are equal then (since we assume
773 // that operands have already been simplified) "select(cond, B, C)" should
774 // have been simplified to the common value of B and C already. Analysing
775 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
776 // for threading over phi nodes.
781 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
782 const DataLayout *DL, const TargetLibraryInfo *TLI,
783 const DominatorTree *DT, AssumptionTracker *AT,
784 const Instruction *CxtI) {
785 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW,
786 Query (DL, TLI, DT, AT, CxtI), RecursionLimit);
789 /// Given operands for an FAdd, see if we can fold the result. If not, this
791 static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
792 const Query &Q, unsigned MaxRecurse) {
793 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
794 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
795 Constant *Ops[] = { CLHS, CRHS };
796 return ConstantFoldInstOperands(Instruction::FAdd, CLHS->getType(),
800 // Canonicalize the constant to the RHS.
805 if (match(Op1, m_NegZero()))
808 // fadd X, 0 ==> X, when we know X is not -0
809 if (match(Op1, m_Zero()) &&
810 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0)))
813 // fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
814 // where nnan and ninf have to occur at least once somewhere in this
816 Value *SubOp = nullptr;
817 if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0))))
819 else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1))))
822 Instruction *FSub = cast<Instruction>(SubOp);
823 if ((FMF.noNaNs() || FSub->hasNoNaNs()) &&
824 (FMF.noInfs() || FSub->hasNoInfs()))
825 return Constant::getNullValue(Op0->getType());
831 /// Given operands for an FSub, see if we can fold the result. If not, this
833 static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
834 const Query &Q, unsigned MaxRecurse) {
835 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
836 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
837 Constant *Ops[] = { CLHS, CRHS };
838 return ConstantFoldInstOperands(Instruction::FSub, CLHS->getType(),
844 if (match(Op1, m_Zero()))
847 // fsub X, -0 ==> X, when we know X is not -0
848 if (match(Op1, m_NegZero()) &&
849 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0)))
852 // fsub 0, (fsub -0.0, X) ==> X
854 if (match(Op0, m_AnyZero())) {
855 if (match(Op1, m_FSub(m_NegZero(), m_Value(X))))
857 if (FMF.noSignedZeros() && match(Op1, m_FSub(m_AnyZero(), m_Value(X))))
861 // fsub nnan ninf x, x ==> 0.0
862 if (FMF.noNaNs() && FMF.noInfs() && Op0 == Op1)
863 return Constant::getNullValue(Op0->getType());
868 /// Given the operands for an FMul, see if we can fold the result
869 static Value *SimplifyFMulInst(Value *Op0, Value *Op1,
872 unsigned MaxRecurse) {
873 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
874 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
875 Constant *Ops[] = { CLHS, CRHS };
876 return ConstantFoldInstOperands(Instruction::FMul, CLHS->getType(),
880 // Canonicalize the constant to the RHS.
885 if (match(Op1, m_FPOne()))
888 // fmul nnan nsz X, 0 ==> 0
889 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero()))
895 /// SimplifyMulInst - Given operands for a Mul, see if we can
896 /// fold the result. If not, this returns null.
897 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
898 unsigned MaxRecurse) {
899 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
900 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
901 Constant *Ops[] = { CLHS, CRHS };
902 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
906 // Canonicalize the constant to the RHS.
911 if (match(Op1, m_Undef()))
912 return Constant::getNullValue(Op0->getType());
915 if (match(Op1, m_Zero()))
919 if (match(Op1, m_One()))
922 // (X / Y) * Y -> X if the division is exact.
924 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
925 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
929 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
930 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
933 // Try some generic simplifications for associative operations.
934 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
938 // Mul distributes over Add. Try some generic simplifications based on this.
939 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
943 // If the operation is with the result of a select instruction, check whether
944 // operating on either branch of the select always yields the same value.
945 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
946 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
950 // If the operation is with the result of a phi instruction, check whether
951 // operating on all incoming values of the phi always yields the same value.
952 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
953 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
960 Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
961 const DataLayout *DL, const TargetLibraryInfo *TLI,
962 const DominatorTree *DT, AssumptionTracker *AT,
963 const Instruction *CxtI) {
964 return ::SimplifyFAddInst(Op0, Op1, FMF, Query (DL, TLI, DT, AT, CxtI),
968 Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
969 const DataLayout *DL, const TargetLibraryInfo *TLI,
970 const DominatorTree *DT, AssumptionTracker *AT,
971 const Instruction *CxtI) {
972 return ::SimplifyFSubInst(Op0, Op1, FMF, Query (DL, TLI, DT, AT, CxtI),
976 Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1,
978 const DataLayout *DL,
979 const TargetLibraryInfo *TLI,
980 const DominatorTree *DT,
981 AssumptionTracker *AT,
982 const Instruction *CxtI) {
983 return ::SimplifyFMulInst(Op0, Op1, FMF, Query (DL, TLI, DT, AT, CxtI),
987 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const DataLayout *DL,
988 const TargetLibraryInfo *TLI,
989 const DominatorTree *DT, AssumptionTracker *AT,
990 const Instruction *CxtI) {
991 return ::SimplifyMulInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
995 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
996 /// fold the result. If not, this returns null.
997 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
998 const Query &Q, unsigned MaxRecurse) {
999 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1000 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1001 Constant *Ops[] = { C0, C1 };
1002 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1006 bool isSigned = Opcode == Instruction::SDiv;
1008 // X / undef -> undef
1009 if (match(Op1, m_Undef()))
1013 if (match(Op0, m_Undef()))
1014 return Constant::getNullValue(Op0->getType());
1016 // 0 / X -> 0, we don't need to preserve faults!
1017 if (match(Op0, m_Zero()))
1021 if (match(Op1, m_One()))
1024 if (Op0->getType()->isIntegerTy(1))
1025 // It can't be division by zero, hence it must be division by one.
1030 return ConstantInt::get(Op0->getType(), 1);
1032 // (X * Y) / Y -> X if the multiplication does not overflow.
1033 Value *X = nullptr, *Y = nullptr;
1034 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
1035 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
1036 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
1037 // If the Mul knows it does not overflow, then we are good to go.
1038 if ((isSigned && Mul->hasNoSignedWrap()) ||
1039 (!isSigned && Mul->hasNoUnsignedWrap()))
1041 // If X has the form X = A / Y then X * Y cannot overflow.
1042 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
1043 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1047 // (X rem Y) / Y -> 0
1048 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1049 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1050 return Constant::getNullValue(Op0->getType());
1052 // (X /u C1) /u C2 -> 0 if C1 * C2 overflow
1053 ConstantInt *C1, *C2;
1054 if (!isSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
1055 match(Op1, m_ConstantInt(C2))) {
1057 C1->getValue().umul_ov(C2->getValue(), Overflow);
1059 return Constant::getNullValue(Op0->getType());
1062 // If the operation is with the result of a select instruction, check whether
1063 // operating on either branch of the select always yields the same value.
1064 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1065 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1068 // If the operation is with the result of a phi instruction, check whether
1069 // operating on all incoming values of the phi always yields the same value.
1070 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1071 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1077 /// SimplifySDivInst - Given operands for an SDiv, see if we can
1078 /// fold the result. If not, this returns null.
1079 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
1080 unsigned MaxRecurse) {
1081 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
1087 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const DataLayout *DL,
1088 const TargetLibraryInfo *TLI,
1089 const DominatorTree *DT,
1090 AssumptionTracker *AT,
1091 const Instruction *CxtI) {
1092 return ::SimplifySDivInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1096 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
1097 /// fold the result. If not, this returns null.
1098 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
1099 unsigned MaxRecurse) {
1100 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
1106 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const DataLayout *DL,
1107 const TargetLibraryInfo *TLI,
1108 const DominatorTree *DT,
1109 AssumptionTracker *AT,
1110 const Instruction *CxtI) {
1111 return ::SimplifyUDivInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1115 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q,
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()))
1128 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const DataLayout *DL,
1129 const TargetLibraryInfo *TLI,
1130 const DominatorTree *DT,
1131 AssumptionTracker *AT,
1132 const Instruction *CxtI) {
1133 return ::SimplifyFDivInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1137 /// SimplifyRem - Given operands for an SRem or URem, see if we can
1138 /// fold the result. If not, this returns null.
1139 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1140 const Query &Q, unsigned MaxRecurse) {
1141 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1142 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1143 Constant *Ops[] = { C0, C1 };
1144 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1148 // X % undef -> undef
1149 if (match(Op1, m_Undef()))
1153 if (match(Op0, m_Undef()))
1154 return Constant::getNullValue(Op0->getType());
1156 // 0 % X -> 0, we don't need to preserve faults!
1157 if (match(Op0, m_Zero()))
1160 // X % 0 -> undef, we don't need to preserve faults!
1161 if (match(Op1, m_Zero()))
1162 return UndefValue::get(Op0->getType());
1165 if (match(Op1, m_One()))
1166 return Constant::getNullValue(Op0->getType());
1168 if (Op0->getType()->isIntegerTy(1))
1169 // It can't be remainder by zero, hence it must be remainder by one.
1170 return Constant::getNullValue(Op0->getType());
1174 return Constant::getNullValue(Op0->getType());
1176 // (X % Y) % Y -> X % Y
1177 if ((Opcode == Instruction::SRem &&
1178 match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1179 (Opcode == Instruction::URem &&
1180 match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1183 // If the operation is with the result of a select instruction, check whether
1184 // operating on either branch of the select always yields the same value.
1185 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1186 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1189 // If the operation is with the result of a phi instruction, check whether
1190 // operating on all incoming values of the phi always yields the same value.
1191 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1192 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1198 /// SimplifySRemInst - Given operands for an SRem, see if we can
1199 /// fold the result. If not, this returns null.
1200 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
1201 unsigned MaxRecurse) {
1202 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
1208 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const DataLayout *DL,
1209 const TargetLibraryInfo *TLI,
1210 const DominatorTree *DT,
1211 AssumptionTracker *AT,
1212 const Instruction *CxtI) {
1213 return ::SimplifySRemInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1217 /// SimplifyURemInst - Given operands for a URem, see if we can
1218 /// fold the result. If not, this returns null.
1219 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
1220 unsigned MaxRecurse) {
1221 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
1227 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const DataLayout *DL,
1228 const TargetLibraryInfo *TLI,
1229 const DominatorTree *DT,
1230 AssumptionTracker *AT,
1231 const Instruction *CxtI) {
1232 return ::SimplifyURemInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1236 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &,
1238 // undef % X -> undef (the undef could be a snan).
1239 if (match(Op0, m_Undef()))
1242 // X % undef -> undef
1243 if (match(Op1, m_Undef()))
1249 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const DataLayout *DL,
1250 const TargetLibraryInfo *TLI,
1251 const DominatorTree *DT,
1252 AssumptionTracker *AT,
1253 const Instruction *CxtI) {
1254 return ::SimplifyFRemInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1258 /// isUndefShift - Returns true if a shift by \c Amount always yields undef.
1259 static bool isUndefShift(Value *Amount) {
1260 Constant *C = dyn_cast<Constant>(Amount);
1264 // X shift by undef -> undef because it may shift by the bitwidth.
1265 if (isa<UndefValue>(C))
1268 // Shifting by the bitwidth or more is undefined.
1269 if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
1270 if (CI->getValue().getLimitedValue() >=
1271 CI->getType()->getScalarSizeInBits())
1274 // If all lanes of a vector shift are undefined the whole shift is.
1275 if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
1276 for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I)
1277 if (!isUndefShift(C->getAggregateElement(I)))
1285 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1286 /// fold the result. If not, this returns null.
1287 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1288 const Query &Q, unsigned MaxRecurse) {
1289 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1290 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1291 Constant *Ops[] = { C0, C1 };
1292 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1296 // 0 shift by X -> 0
1297 if (match(Op0, m_Zero()))
1300 // X shift by 0 -> X
1301 if (match(Op1, m_Zero()))
1304 // Fold undefined shifts.
1305 if (isUndefShift(Op1))
1306 return UndefValue::get(Op0->getType());
1308 // If the operation is with the result of a select instruction, check whether
1309 // operating on either branch of the select always yields the same value.
1310 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1311 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1314 // If the operation is with the result of a phi instruction, check whether
1315 // operating on all incoming values of the phi always yields the same value.
1316 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1317 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1323 /// \brief Given operands for an Shl, LShr or AShr, see if we can
1324 /// fold the result. If not, this returns null.
1325 static Value *SimplifyRightShift(unsigned Opcode, Value *Op0, Value *Op1,
1326 bool isExact, const Query &Q,
1327 unsigned MaxRecurse) {
1328 if (Value *V = SimplifyShift(Opcode, Op0, Op1, Q, MaxRecurse))
1333 return Constant::getNullValue(Op0->getType());
1335 // The low bit cannot be shifted out of an exact shift if it is set.
1337 unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
1338 APInt Op0KnownZero(BitWidth, 0);
1339 APInt Op0KnownOne(BitWidth, 0);
1340 computeKnownBits(Op0, Op0KnownZero, Op0KnownOne, Q.DL, /*Depth=*/0, Q.AT, Q.CxtI,
1349 /// SimplifyShlInst - Given operands for an Shl, see if we can
1350 /// fold the result. If not, this returns null.
1351 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1352 const Query &Q, unsigned MaxRecurse) {
1353 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1357 if (match(Op0, m_Undef()))
1358 return Constant::getNullValue(Op0->getType());
1360 // (X >> A) << A -> X
1362 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1367 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1368 const DataLayout *DL, const TargetLibraryInfo *TLI,
1369 const DominatorTree *DT, AssumptionTracker *AT,
1370 const Instruction *CxtI) {
1371 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (DL, TLI, DT, AT, CxtI),
1375 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1376 /// fold the result. If not, this returns null.
1377 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1378 const Query &Q, unsigned MaxRecurse) {
1379 if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q,
1384 if (match(Op0, m_Undef()))
1385 return Constant::getNullValue(Op0->getType());
1387 // (X << A) >> A -> X
1389 if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
1395 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1396 const DataLayout *DL,
1397 const TargetLibraryInfo *TLI,
1398 const DominatorTree *DT,
1399 AssumptionTracker *AT,
1400 const Instruction *CxtI) {
1401 return ::SimplifyLShrInst(Op0, Op1, isExact, Query (DL, TLI, DT, AT, CxtI),
1405 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1406 /// fold the result. If not, this returns null.
1407 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1408 const Query &Q, unsigned MaxRecurse) {
1409 if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
1413 // all ones >>a X -> all ones
1414 if (match(Op0, m_AllOnes()))
1417 // undef >>a X -> all ones
1418 if (match(Op0, m_Undef()))
1419 return Constant::getAllOnesValue(Op0->getType());
1421 // (X << A) >> A -> X
1423 if (match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
1426 // Arithmetic shifting an all-sign-bit value is a no-op.
1427 unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AT, Q.CxtI, Q.DT);
1428 if (NumSignBits == Op0->getType()->getScalarSizeInBits())
1434 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1435 const DataLayout *DL,
1436 const TargetLibraryInfo *TLI,
1437 const DominatorTree *DT,
1438 AssumptionTracker *AT,
1439 const Instruction *CxtI) {
1440 return ::SimplifyAShrInst(Op0, Op1, isExact, Query (DL, TLI, DT, AT, CxtI),
1444 // Simplify (and (icmp ...) (icmp ...)) to true when we can tell that the range
1445 // of possible values cannot be satisfied.
1446 static Value *SimplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
1447 ICmpInst::Predicate Pred0, Pred1;
1448 ConstantInt *CI1, *CI2;
1450 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
1451 m_ConstantInt(CI2))))
1454 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
1457 Type *ITy = Op0->getType();
1459 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1460 bool isNSW = AddInst->hasNoSignedWrap();
1461 bool isNUW = AddInst->hasNoUnsignedWrap();
1463 const APInt &CI1V = CI1->getValue();
1464 const APInt &CI2V = CI2->getValue();
1465 const APInt Delta = CI2V - CI1V;
1466 if (CI1V.isStrictlyPositive()) {
1468 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
1469 return getFalse(ITy);
1470 if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1471 return getFalse(ITy);
1474 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
1475 return getFalse(ITy);
1476 if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1477 return getFalse(ITy);
1480 if (CI1V.getBoolValue() && isNUW) {
1482 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
1483 return getFalse(ITy);
1485 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
1486 return getFalse(ITy);
1492 /// SimplifyAndInst - Given operands for an And, see if we can
1493 /// fold the result. If not, this returns null.
1494 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
1495 unsigned MaxRecurse) {
1496 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1497 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1498 Constant *Ops[] = { CLHS, CRHS };
1499 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1503 // Canonicalize the constant to the RHS.
1504 std::swap(Op0, Op1);
1508 if (match(Op1, m_Undef()))
1509 return Constant::getNullValue(Op0->getType());
1516 if (match(Op1, m_Zero()))
1520 if (match(Op1, m_AllOnes()))
1523 // A & ~A = ~A & A = 0
1524 if (match(Op0, m_Not(m_Specific(Op1))) ||
1525 match(Op1, m_Not(m_Specific(Op0))))
1526 return Constant::getNullValue(Op0->getType());
1529 Value *A = nullptr, *B = nullptr;
1530 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1531 (A == Op1 || B == Op1))
1535 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1536 (A == Op0 || B == Op0))
1539 // A & (-A) = A if A is a power of two or zero.
1540 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1541 match(Op1, m_Neg(m_Specific(Op0)))) {
1542 if (isKnownToBeAPowerOfTwo(Op0, /*OrZero*/true, 0, Q.AT, Q.CxtI, Q.DT))
1544 if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/true, 0, Q.AT, Q.CxtI, Q.DT))
1548 if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
1549 if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
1550 if (Value *V = SimplifyAndOfICmps(ICILHS, ICIRHS))
1552 if (Value *V = SimplifyAndOfICmps(ICIRHS, ICILHS))
1557 // Try some generic simplifications for associative operations.
1558 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1562 // And distributes over Or. Try some generic simplifications based on this.
1563 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1567 // And distributes over Xor. Try some generic simplifications based on this.
1568 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1572 // If the operation is with the result of a select instruction, check whether
1573 // operating on either branch of the select always yields the same value.
1574 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1575 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1579 // If the operation is with the result of a phi instruction, check whether
1580 // operating on all incoming values of the phi always yields the same value.
1581 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1582 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1589 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout *DL,
1590 const TargetLibraryInfo *TLI,
1591 const DominatorTree *DT, AssumptionTracker *AT,
1592 const Instruction *CxtI) {
1593 return ::SimplifyAndInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1597 // Simplify (or (icmp ...) (icmp ...)) to true when we can tell that the union
1598 // contains all possible values.
1599 static Value *SimplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
1600 ICmpInst::Predicate Pred0, Pred1;
1601 ConstantInt *CI1, *CI2;
1603 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
1604 m_ConstantInt(CI2))))
1607 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
1610 Type *ITy = Op0->getType();
1612 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1613 bool isNSW = AddInst->hasNoSignedWrap();
1614 bool isNUW = AddInst->hasNoUnsignedWrap();
1616 const APInt &CI1V = CI1->getValue();
1617 const APInt &CI2V = CI2->getValue();
1618 const APInt Delta = CI2V - CI1V;
1619 if (CI1V.isStrictlyPositive()) {
1621 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
1622 return getTrue(ITy);
1623 if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1624 return getTrue(ITy);
1627 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
1628 return getTrue(ITy);
1629 if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1630 return getTrue(ITy);
1633 if (CI1V.getBoolValue() && isNUW) {
1635 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
1636 return getTrue(ITy);
1638 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
1639 return getTrue(ITy);
1645 /// SimplifyOrInst - Given operands for an Or, see if we can
1646 /// fold the result. If not, this returns null.
1647 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
1648 unsigned MaxRecurse) {
1649 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1650 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1651 Constant *Ops[] = { CLHS, CRHS };
1652 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1656 // Canonicalize the constant to the RHS.
1657 std::swap(Op0, Op1);
1661 if (match(Op1, m_Undef()))
1662 return Constant::getAllOnesValue(Op0->getType());
1669 if (match(Op1, m_Zero()))
1673 if (match(Op1, m_AllOnes()))
1676 // A | ~A = ~A | A = -1
1677 if (match(Op0, m_Not(m_Specific(Op1))) ||
1678 match(Op1, m_Not(m_Specific(Op0))))
1679 return Constant::getAllOnesValue(Op0->getType());
1682 Value *A = nullptr, *B = nullptr;
1683 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1684 (A == Op1 || B == Op1))
1688 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1689 (A == Op0 || B == Op0))
1692 // ~(A & ?) | A = -1
1693 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1694 (A == Op1 || B == Op1))
1695 return Constant::getAllOnesValue(Op1->getType());
1697 // A | ~(A & ?) = -1
1698 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1699 (A == Op0 || B == Op0))
1700 return Constant::getAllOnesValue(Op0->getType());
1702 if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
1703 if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
1704 if (Value *V = SimplifyOrOfICmps(ICILHS, ICIRHS))
1706 if (Value *V = SimplifyOrOfICmps(ICIRHS, ICILHS))
1711 // Try some generic simplifications for associative operations.
1712 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1716 // Or distributes over And. Try some generic simplifications based on this.
1717 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1721 // If the operation is with the result of a select instruction, check whether
1722 // operating on either branch of the select always yields the same value.
1723 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1724 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1729 Value *C = nullptr, *D = nullptr;
1730 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
1731 match(Op1, m_And(m_Value(B), m_Value(D)))) {
1732 ConstantInt *C1 = dyn_cast<ConstantInt>(C);
1733 ConstantInt *C2 = dyn_cast<ConstantInt>(D);
1734 if (C1 && C2 && (C1->getValue() == ~C2->getValue())) {
1735 // (A & C1)|(B & C2)
1736 // If we have: ((V + N) & C1) | (V & C2)
1737 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1738 // replace with V+N.
1740 if ((C2->getValue() & (C2->getValue() + 1)) == 0 && // C2 == 0+1+
1741 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
1742 // Add commutes, try both ways.
1743 if (V1 == B && MaskedValueIsZero(V2, C2->getValue(), Q.DL,
1744 0, Q.AT, Q.CxtI, Q.DT))
1746 if (V2 == B && MaskedValueIsZero(V1, C2->getValue(), Q.DL,
1747 0, Q.AT, Q.CxtI, Q.DT))
1750 // Or commutes, try both ways.
1751 if ((C1->getValue() & (C1->getValue() + 1)) == 0 &&
1752 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
1753 // Add commutes, try both ways.
1754 if (V1 == A && MaskedValueIsZero(V2, C1->getValue(), Q.DL,
1755 0, Q.AT, Q.CxtI, Q.DT))
1757 if (V2 == A && MaskedValueIsZero(V1, C1->getValue(), Q.DL,
1758 0, Q.AT, Q.CxtI, Q.DT))
1764 // If the operation is with the result of a phi instruction, check whether
1765 // operating on all incoming values of the phi always yields the same value.
1766 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1767 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1773 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const DataLayout *DL,
1774 const TargetLibraryInfo *TLI,
1775 const DominatorTree *DT, AssumptionTracker *AT,
1776 const Instruction *CxtI) {
1777 return ::SimplifyOrInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1781 /// SimplifyXorInst - Given operands for a Xor, see if we can
1782 /// fold the result. If not, this returns null.
1783 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q,
1784 unsigned MaxRecurse) {
1785 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1786 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1787 Constant *Ops[] = { CLHS, CRHS };
1788 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1792 // Canonicalize the constant to the RHS.
1793 std::swap(Op0, Op1);
1796 // A ^ undef -> undef
1797 if (match(Op1, m_Undef()))
1801 if (match(Op1, m_Zero()))
1806 return Constant::getNullValue(Op0->getType());
1808 // A ^ ~A = ~A ^ A = -1
1809 if (match(Op0, m_Not(m_Specific(Op1))) ||
1810 match(Op1, m_Not(m_Specific(Op0))))
1811 return Constant::getAllOnesValue(Op0->getType());
1813 // Try some generic simplifications for associative operations.
1814 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1818 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1819 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1820 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1821 // only if B and C are equal. If B and C are equal then (since we assume
1822 // that operands have already been simplified) "select(cond, B, C)" should
1823 // have been simplified to the common value of B and C already. Analysing
1824 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1825 // for threading over phi nodes.
1830 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const DataLayout *DL,
1831 const TargetLibraryInfo *TLI,
1832 const DominatorTree *DT, AssumptionTracker *AT,
1833 const Instruction *CxtI) {
1834 return ::SimplifyXorInst(Op0, Op1, Query (DL, TLI, DT, AT, CxtI),
1838 static Type *GetCompareTy(Value *Op) {
1839 return CmpInst::makeCmpResultType(Op->getType());
1842 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1843 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1844 /// otherwise return null. Helper function for analyzing max/min idioms.
1845 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1846 Value *LHS, Value *RHS) {
1847 SelectInst *SI = dyn_cast<SelectInst>(V);
1850 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1853 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1854 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1856 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1857 LHS == CmpRHS && RHS == CmpLHS)
1862 // A significant optimization not implemented here is assuming that alloca
1863 // addresses are not equal to incoming argument values. They don't *alias*,
1864 // as we say, but that doesn't mean they aren't equal, so we take a
1865 // conservative approach.
1867 // This is inspired in part by C++11 5.10p1:
1868 // "Two pointers of the same type compare equal if and only if they are both
1869 // null, both point to the same function, or both represent the same
1872 // This is pretty permissive.
1874 // It's also partly due to C11 6.5.9p6:
1875 // "Two pointers compare equal if and only if both are null pointers, both are
1876 // pointers to the same object (including a pointer to an object and a
1877 // subobject at its beginning) or function, both are pointers to one past the
1878 // last element of the same array object, or one is a pointer to one past the
1879 // end of one array object and the other is a pointer to the start of a
1880 // different array object that happens to immediately follow the first array
1881 // object in the address space.)
1883 // C11's version is more restrictive, however there's no reason why an argument
1884 // couldn't be a one-past-the-end value for a stack object in the caller and be
1885 // equal to the beginning of a stack object in the callee.
1887 // If the C and C++ standards are ever made sufficiently restrictive in this
1888 // area, it may be possible to update LLVM's semantics accordingly and reinstate
1889 // this optimization.
1890 static Constant *computePointerICmp(const DataLayout *DL,
1891 const TargetLibraryInfo *TLI,
1892 CmpInst::Predicate Pred,
1893 Value *LHS, Value *RHS) {
1894 // First, skip past any trivial no-ops.
1895 LHS = LHS->stripPointerCasts();
1896 RHS = RHS->stripPointerCasts();
1898 // A non-null pointer is not equal to a null pointer.
1899 if (llvm::isKnownNonNull(LHS, TLI) && isa<ConstantPointerNull>(RHS) &&
1900 (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE))
1901 return ConstantInt::get(GetCompareTy(LHS),
1902 !CmpInst::isTrueWhenEqual(Pred));
1904 // We can only fold certain predicates on pointer comparisons.
1909 // Equality comaprisons are easy to fold.
1910 case CmpInst::ICMP_EQ:
1911 case CmpInst::ICMP_NE:
1914 // We can only handle unsigned relational comparisons because 'inbounds' on
1915 // a GEP only protects against unsigned wrapping.
1916 case CmpInst::ICMP_UGT:
1917 case CmpInst::ICMP_UGE:
1918 case CmpInst::ICMP_ULT:
1919 case CmpInst::ICMP_ULE:
1920 // However, we have to switch them to their signed variants to handle
1921 // negative indices from the base pointer.
1922 Pred = ICmpInst::getSignedPredicate(Pred);
1926 // Strip off any constant offsets so that we can reason about them.
1927 // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
1928 // here and compare base addresses like AliasAnalysis does, however there are
1929 // numerous hazards. AliasAnalysis and its utilities rely on special rules
1930 // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
1931 // doesn't need to guarantee pointer inequality when it says NoAlias.
1932 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
1933 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
1935 // If LHS and RHS are related via constant offsets to the same base
1936 // value, we can replace it with an icmp which just compares the offsets.
1938 return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
1940 // Various optimizations for (in)equality comparisons.
1941 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
1942 // Different non-empty allocations that exist at the same time have
1943 // different addresses (if the program can tell). Global variables always
1944 // exist, so they always exist during the lifetime of each other and all
1945 // allocas. Two different allocas usually have different addresses...
1947 // However, if there's an @llvm.stackrestore dynamically in between two
1948 // allocas, they may have the same address. It's tempting to reduce the
1949 // scope of the problem by only looking at *static* allocas here. That would
1950 // cover the majority of allocas while significantly reducing the likelihood
1951 // of having an @llvm.stackrestore pop up in the middle. However, it's not
1952 // actually impossible for an @llvm.stackrestore to pop up in the middle of
1953 // an entry block. Also, if we have a block that's not attached to a
1954 // function, we can't tell if it's "static" under the current definition.
1955 // Theoretically, this problem could be fixed by creating a new kind of
1956 // instruction kind specifically for static allocas. Such a new instruction
1957 // could be required to be at the top of the entry block, thus preventing it
1958 // from being subject to a @llvm.stackrestore. Instcombine could even
1959 // convert regular allocas into these special allocas. It'd be nifty.
1960 // However, until then, this problem remains open.
1962 // So, we'll assume that two non-empty allocas have different addresses
1965 // With all that, if the offsets are within the bounds of their allocations
1966 // (and not one-past-the-end! so we can't use inbounds!), and their
1967 // allocations aren't the same, the pointers are not equal.
1969 // Note that it's not necessary to check for LHS being a global variable
1970 // address, due to canonicalization and constant folding.
1971 if (isa<AllocaInst>(LHS) &&
1972 (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
1973 ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
1974 ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
1975 uint64_t LHSSize, RHSSize;
1976 if (LHSOffsetCI && RHSOffsetCI &&
1977 getObjectSize(LHS, LHSSize, DL, TLI) &&
1978 getObjectSize(RHS, RHSSize, DL, TLI)) {
1979 const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
1980 const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
1981 if (!LHSOffsetValue.isNegative() &&
1982 !RHSOffsetValue.isNegative() &&
1983 LHSOffsetValue.ult(LHSSize) &&
1984 RHSOffsetValue.ult(RHSSize)) {
1985 return ConstantInt::get(GetCompareTy(LHS),
1986 !CmpInst::isTrueWhenEqual(Pred));
1990 // Repeat the above check but this time without depending on DataLayout
1991 // or being able to compute a precise size.
1992 if (!cast<PointerType>(LHS->getType())->isEmptyTy() &&
1993 !cast<PointerType>(RHS->getType())->isEmptyTy() &&
1994 LHSOffset->isNullValue() &&
1995 RHSOffset->isNullValue())
1996 return ConstantInt::get(GetCompareTy(LHS),
1997 !CmpInst::isTrueWhenEqual(Pred));
2000 // Even if an non-inbounds GEP occurs along the path we can still optimize
2001 // equality comparisons concerning the result. We avoid walking the whole
2002 // chain again by starting where the last calls to
2003 // stripAndComputeConstantOffsets left off and accumulate the offsets.
2004 Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true);
2005 Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true);
2007 return ConstantExpr::getICmp(Pred,
2008 ConstantExpr::getAdd(LHSOffset, LHSNoBound),
2009 ConstantExpr::getAdd(RHSOffset, RHSNoBound));
2016 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
2017 /// fold the result. If not, this returns null.
2018 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2019 const Query &Q, unsigned MaxRecurse) {
2020 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2021 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
2023 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2024 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2025 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
2027 // If we have a constant, make sure it is on the RHS.
2028 std::swap(LHS, RHS);
2029 Pred = CmpInst::getSwappedPredicate(Pred);
2032 Type *ITy = GetCompareTy(LHS); // The return type.
2033 Type *OpTy = LHS->getType(); // The operand type.
2035 // icmp X, X -> true/false
2036 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
2037 // because X could be 0.
2038 if (LHS == RHS || isa<UndefValue>(RHS))
2039 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
2041 // Special case logic when the operands have i1 type.
2042 if (OpTy->getScalarType()->isIntegerTy(1)) {
2045 case ICmpInst::ICMP_EQ:
2047 if (match(RHS, m_One()))
2050 case ICmpInst::ICMP_NE:
2052 if (match(RHS, m_Zero()))
2055 case ICmpInst::ICMP_UGT:
2057 if (match(RHS, m_Zero()))
2060 case ICmpInst::ICMP_UGE:
2062 if (match(RHS, m_One()))
2065 case ICmpInst::ICMP_SLT:
2067 if (match(RHS, m_Zero()))
2070 case ICmpInst::ICMP_SLE:
2072 if (match(RHS, m_One()))
2078 // If we are comparing with zero then try hard since this is a common case.
2079 if (match(RHS, m_Zero())) {
2080 bool LHSKnownNonNegative, LHSKnownNegative;
2082 default: llvm_unreachable("Unknown ICmp predicate!");
2083 case ICmpInst::ICMP_ULT:
2084 return getFalse(ITy);
2085 case ICmpInst::ICMP_UGE:
2086 return getTrue(ITy);
2087 case ICmpInst::ICMP_EQ:
2088 case ICmpInst::ICMP_ULE:
2089 if (isKnownNonZero(LHS, Q.DL, 0, Q.AT, Q.CxtI, Q.DT))
2090 return getFalse(ITy);
2092 case ICmpInst::ICMP_NE:
2093 case ICmpInst::ICMP_UGT:
2094 if (isKnownNonZero(LHS, Q.DL, 0, Q.AT, Q.CxtI, Q.DT))
2095 return getTrue(ITy);
2097 case ICmpInst::ICMP_SLT:
2098 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL,
2099 0, Q.AT, Q.CxtI, Q.DT);
2100 if (LHSKnownNegative)
2101 return getTrue(ITy);
2102 if (LHSKnownNonNegative)
2103 return getFalse(ITy);
2105 case ICmpInst::ICMP_SLE:
2106 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL,
2107 0, Q.AT, Q.CxtI, Q.DT);
2108 if (LHSKnownNegative)
2109 return getTrue(ITy);
2110 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.DL,
2111 0, Q.AT, Q.CxtI, Q.DT))
2112 return getFalse(ITy);
2114 case ICmpInst::ICMP_SGE:
2115 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL,
2116 0, Q.AT, Q.CxtI, Q.DT);
2117 if (LHSKnownNegative)
2118 return getFalse(ITy);
2119 if (LHSKnownNonNegative)
2120 return getTrue(ITy);
2122 case ICmpInst::ICMP_SGT:
2123 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL,
2124 0, Q.AT, Q.CxtI, Q.DT);
2125 if (LHSKnownNegative)
2126 return getFalse(ITy);
2127 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.DL,
2128 0, Q.AT, Q.CxtI, Q.DT))
2129 return getTrue(ITy);
2134 // See if we are doing a comparison with a constant integer.
2135 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2136 // Rule out tautological comparisons (eg., ult 0 or uge 0).
2137 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
2138 if (RHS_CR.isEmptySet())
2139 return ConstantInt::getFalse(CI->getContext());
2140 if (RHS_CR.isFullSet())
2141 return ConstantInt::getTrue(CI->getContext());
2143 // Many binary operators with constant RHS have easy to compute constant
2144 // range. Use them to check whether the comparison is a tautology.
2145 unsigned Width = CI->getBitWidth();
2146 APInt Lower = APInt(Width, 0);
2147 APInt Upper = APInt(Width, 0);
2149 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
2150 // 'urem x, CI2' produces [0, CI2).
2151 Upper = CI2->getValue();
2152 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
2153 // 'srem x, CI2' produces (-|CI2|, |CI2|).
2154 Upper = CI2->getValue().abs();
2155 Lower = (-Upper) + 1;
2156 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
2157 // 'udiv CI2, x' produces [0, CI2].
2158 Upper = CI2->getValue() + 1;
2159 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
2160 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
2161 APInt NegOne = APInt::getAllOnesValue(Width);
2163 Upper = NegOne.udiv(CI2->getValue()) + 1;
2164 } else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) {
2165 if (CI2->isMinSignedValue()) {
2166 // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
2167 Lower = CI2->getValue();
2168 Upper = Lower.lshr(1) + 1;
2170 // 'sdiv CI2, x' produces [-|CI2|, |CI2|].
2171 Upper = CI2->getValue().abs() + 1;
2172 Lower = (-Upper) + 1;
2174 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
2175 APInt IntMin = APInt::getSignedMinValue(Width);
2176 APInt IntMax = APInt::getSignedMaxValue(Width);
2177 APInt Val = CI2->getValue();
2178 if (Val.isAllOnesValue()) {
2179 // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
2180 // where CI2 != -1 and CI2 != 0 and CI2 != 1
2183 } else if (Val.countLeadingZeros() < Width - 1) {
2184 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]
2185 // where CI2 != -1 and CI2 != 0 and CI2 != 1
2186 Lower = IntMin.sdiv(Val);
2187 Upper = IntMax.sdiv(Val);
2188 if (Lower.sgt(Upper))
2189 std::swap(Lower, Upper);
2191 assert(Upper != Lower && "Upper part of range has wrapped!");
2193 } else if (match(LHS, m_NUWShl(m_ConstantInt(CI2), m_Value()))) {
2194 // 'shl nuw CI2, x' produces [CI2, CI2 << CLZ(CI2)]
2195 Lower = CI2->getValue();
2196 Upper = Lower.shl(Lower.countLeadingZeros()) + 1;
2197 } else if (match(LHS, m_NSWShl(m_ConstantInt(CI2), m_Value()))) {
2198 if (CI2->isNegative()) {
2199 // 'shl nsw CI2, x' produces [CI2 << CLO(CI2)-1, CI2]
2200 unsigned ShiftAmount = CI2->getValue().countLeadingOnes() - 1;
2201 Lower = CI2->getValue().shl(ShiftAmount);
2202 Upper = CI2->getValue() + 1;
2204 // 'shl nsw CI2, x' produces [CI2, CI2 << CLZ(CI2)-1]
2205 unsigned ShiftAmount = CI2->getValue().countLeadingZeros() - 1;
2206 Lower = CI2->getValue();
2207 Upper = CI2->getValue().shl(ShiftAmount) + 1;
2209 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
2210 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
2211 APInt NegOne = APInt::getAllOnesValue(Width);
2212 if (CI2->getValue().ult(Width))
2213 Upper = NegOne.lshr(CI2->getValue()) + 1;
2214 } else if (match(LHS, m_LShr(m_ConstantInt(CI2), m_Value()))) {
2215 // 'lshr CI2, x' produces [CI2 >> (Width-1), CI2].
2216 unsigned ShiftAmount = Width - 1;
2217 if (!CI2->isZero() && cast<BinaryOperator>(LHS)->isExact())
2218 ShiftAmount = CI2->getValue().countTrailingZeros();
2219 Lower = CI2->getValue().lshr(ShiftAmount);
2220 Upper = CI2->getValue() + 1;
2221 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
2222 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
2223 APInt IntMin = APInt::getSignedMinValue(Width);
2224 APInt IntMax = APInt::getSignedMaxValue(Width);
2225 if (CI2->getValue().ult(Width)) {
2226 Lower = IntMin.ashr(CI2->getValue());
2227 Upper = IntMax.ashr(CI2->getValue()) + 1;
2229 } else if (match(LHS, m_AShr(m_ConstantInt(CI2), m_Value()))) {
2230 unsigned ShiftAmount = Width - 1;
2231 if (!CI2->isZero() && cast<BinaryOperator>(LHS)->isExact())
2232 ShiftAmount = CI2->getValue().countTrailingZeros();
2233 if (CI2->isNegative()) {
2234 // 'ashr CI2, x' produces [CI2, CI2 >> (Width-1)]
2235 Lower = CI2->getValue();
2236 Upper = CI2->getValue().ashr(ShiftAmount) + 1;
2238 // 'ashr CI2, x' produces [CI2 >> (Width-1), CI2]
2239 Lower = CI2->getValue().ashr(ShiftAmount);
2240 Upper = CI2->getValue() + 1;
2242 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
2243 // 'or x, CI2' produces [CI2, UINT_MAX].
2244 Lower = CI2->getValue();
2245 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
2246 // 'and x, CI2' produces [0, CI2].
2247 Upper = CI2->getValue() + 1;
2249 if (Lower != Upper) {
2250 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
2251 if (RHS_CR.contains(LHS_CR))
2252 return ConstantInt::getTrue(RHS->getContext());
2253 if (RHS_CR.inverse().contains(LHS_CR))
2254 return ConstantInt::getFalse(RHS->getContext());
2258 // Compare of cast, for example (zext X) != 0 -> X != 0
2259 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
2260 Instruction *LI = cast<CastInst>(LHS);
2261 Value *SrcOp = LI->getOperand(0);
2262 Type *SrcTy = SrcOp->getType();
2263 Type *DstTy = LI->getType();
2265 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
2266 // if the integer type is the same size as the pointer type.
2267 if (MaxRecurse && Q.DL && isa<PtrToIntInst>(LI) &&
2268 Q.DL->getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
2269 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2270 // Transfer the cast to the constant.
2271 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
2272 ConstantExpr::getIntToPtr(RHSC, SrcTy),
2275 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
2276 if (RI->getOperand(0)->getType() == SrcTy)
2277 // Compare without the cast.
2278 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
2284 if (isa<ZExtInst>(LHS)) {
2285 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
2287 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
2288 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
2289 // Compare X and Y. Note that signed predicates become unsigned.
2290 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
2291 SrcOp, RI->getOperand(0), Q,
2295 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
2296 // too. If not, then try to deduce the result of the comparison.
2297 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2298 // Compute the constant that would happen if we truncated to SrcTy then
2299 // reextended to DstTy.
2300 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
2301 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
2303 // If the re-extended constant didn't change then this is effectively
2304 // also a case of comparing two zero-extended values.
2305 if (RExt == CI && MaxRecurse)
2306 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
2307 SrcOp, Trunc, Q, MaxRecurse-1))
2310 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
2311 // there. Use this to work out the result of the comparison.
2314 default: llvm_unreachable("Unknown ICmp predicate!");
2316 case ICmpInst::ICMP_EQ:
2317 case ICmpInst::ICMP_UGT:
2318 case ICmpInst::ICMP_UGE:
2319 return ConstantInt::getFalse(CI->getContext());
2321 case ICmpInst::ICMP_NE:
2322 case ICmpInst::ICMP_ULT:
2323 case ICmpInst::ICMP_ULE:
2324 return ConstantInt::getTrue(CI->getContext());
2326 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
2327 // is non-negative then LHS <s RHS.
2328 case ICmpInst::ICMP_SGT:
2329 case ICmpInst::ICMP_SGE:
2330 return CI->getValue().isNegative() ?
2331 ConstantInt::getTrue(CI->getContext()) :
2332 ConstantInt::getFalse(CI->getContext());
2334 case ICmpInst::ICMP_SLT:
2335 case ICmpInst::ICMP_SLE:
2336 return CI->getValue().isNegative() ?
2337 ConstantInt::getFalse(CI->getContext()) :
2338 ConstantInt::getTrue(CI->getContext());
2344 if (isa<SExtInst>(LHS)) {
2345 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
2347 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
2348 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
2349 // Compare X and Y. Note that the predicate does not change.
2350 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
2354 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
2355 // too. If not, then try to deduce the result of the comparison.
2356 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2357 // Compute the constant that would happen if we truncated to SrcTy then
2358 // reextended to DstTy.
2359 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
2360 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
2362 // If the re-extended constant didn't change then this is effectively
2363 // also a case of comparing two sign-extended values.
2364 if (RExt == CI && MaxRecurse)
2365 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
2368 // Otherwise the upper bits of LHS are all equal, while RHS has varying
2369 // bits there. Use this to work out the result of the comparison.
2372 default: llvm_unreachable("Unknown ICmp predicate!");
2373 case ICmpInst::ICMP_EQ:
2374 return ConstantInt::getFalse(CI->getContext());
2375 case ICmpInst::ICMP_NE:
2376 return ConstantInt::getTrue(CI->getContext());
2378 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
2380 case ICmpInst::ICMP_SGT:
2381 case ICmpInst::ICMP_SGE:
2382 return CI->getValue().isNegative() ?
2383 ConstantInt::getTrue(CI->getContext()) :
2384 ConstantInt::getFalse(CI->getContext());
2385 case ICmpInst::ICMP_SLT:
2386 case ICmpInst::ICMP_SLE:
2387 return CI->getValue().isNegative() ?
2388 ConstantInt::getFalse(CI->getContext()) :
2389 ConstantInt::getTrue(CI->getContext());
2391 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
2393 case ICmpInst::ICMP_UGT:
2394 case ICmpInst::ICMP_UGE:
2395 // Comparison is true iff the LHS <s 0.
2397 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
2398 Constant::getNullValue(SrcTy),
2402 case ICmpInst::ICMP_ULT:
2403 case ICmpInst::ICMP_ULE:
2404 // Comparison is true iff the LHS >=s 0.
2406 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
2407 Constant::getNullValue(SrcTy),
2417 // Special logic for binary operators.
2418 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2419 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2420 if (MaxRecurse && (LBO || RBO)) {
2421 // Analyze the case when either LHS or RHS is an add instruction.
2422 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2423 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2424 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2425 if (LBO && LBO->getOpcode() == Instruction::Add) {
2426 A = LBO->getOperand(0); B = LBO->getOperand(1);
2427 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
2428 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
2429 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
2431 if (RBO && RBO->getOpcode() == Instruction::Add) {
2432 C = RBO->getOperand(0); D = RBO->getOperand(1);
2433 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
2434 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2435 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2438 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2439 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2440 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2441 Constant::getNullValue(RHS->getType()),
2445 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2446 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2447 if (Value *V = SimplifyICmpInst(Pred,
2448 Constant::getNullValue(LHS->getType()),
2449 C == LHS ? D : C, Q, MaxRecurse-1))
2452 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2453 if (A && C && (A == C || A == D || B == C || B == D) &&
2454 NoLHSWrapProblem && NoRHSWrapProblem) {
2455 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2458 // C + B == C + D -> B == D
2461 } else if (A == D) {
2462 // D + B == C + D -> B == C
2465 } else if (B == C) {
2466 // A + C == C + D -> A == D
2471 // A + D == C + D -> A == C
2475 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
2480 // icmp pred (or X, Y), X
2481 if (LBO && match(LBO, m_CombineOr(m_Or(m_Value(), m_Specific(RHS)),
2482 m_Or(m_Specific(RHS), m_Value())))) {
2483 if (Pred == ICmpInst::ICMP_ULT)
2484 return getFalse(ITy);
2485 if (Pred == ICmpInst::ICMP_UGE)
2486 return getTrue(ITy);
2488 // icmp pred X, (or X, Y)
2489 if (RBO && match(RBO, m_CombineOr(m_Or(m_Value(), m_Specific(LHS)),
2490 m_Or(m_Specific(LHS), m_Value())))) {
2491 if (Pred == ICmpInst::ICMP_ULE)
2492 return getTrue(ITy);
2493 if (Pred == ICmpInst::ICMP_UGT)
2494 return getFalse(ITy);
2497 // icmp pred (and X, Y), X
2498 if (LBO && match(LBO, m_CombineOr(m_And(m_Value(), m_Specific(RHS)),
2499 m_And(m_Specific(RHS), m_Value())))) {
2500 if (Pred == ICmpInst::ICMP_UGT)
2501 return getFalse(ITy);
2502 if (Pred == ICmpInst::ICMP_ULE)
2503 return getTrue(ITy);
2505 // icmp pred X, (and X, Y)
2506 if (RBO && match(RBO, m_CombineOr(m_And(m_Value(), m_Specific(LHS)),
2507 m_And(m_Specific(LHS), m_Value())))) {
2508 if (Pred == ICmpInst::ICMP_UGE)
2509 return getTrue(ITy);
2510 if (Pred == ICmpInst::ICMP_ULT)
2511 return getFalse(ITy);
2514 // 0 - (zext X) pred C
2515 if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
2516 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
2517 if (RHSC->getValue().isStrictlyPositive()) {
2518 if (Pred == ICmpInst::ICMP_SLT)
2519 return ConstantInt::getTrue(RHSC->getContext());
2520 if (Pred == ICmpInst::ICMP_SGE)
2521 return ConstantInt::getFalse(RHSC->getContext());
2522 if (Pred == ICmpInst::ICMP_EQ)
2523 return ConstantInt::getFalse(RHSC->getContext());
2524 if (Pred == ICmpInst::ICMP_NE)
2525 return ConstantInt::getTrue(RHSC->getContext());
2527 if (RHSC->getValue().isNonNegative()) {
2528 if (Pred == ICmpInst::ICMP_SLE)
2529 return ConstantInt::getTrue(RHSC->getContext());
2530 if (Pred == ICmpInst::ICMP_SGT)
2531 return ConstantInt::getFalse(RHSC->getContext());
2536 // icmp pred (urem X, Y), Y
2537 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2538 bool KnownNonNegative, KnownNegative;
2542 case ICmpInst::ICMP_SGT:
2543 case ICmpInst::ICMP_SGE:
2544 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL,
2545 0, Q.AT, Q.CxtI, Q.DT);
2546 if (!KnownNonNegative)
2549 case ICmpInst::ICMP_EQ:
2550 case ICmpInst::ICMP_UGT:
2551 case ICmpInst::ICMP_UGE:
2552 return getFalse(ITy);
2553 case ICmpInst::ICMP_SLT:
2554 case ICmpInst::ICMP_SLE:
2555 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL,
2556 0, Q.AT, Q.CxtI, Q.DT);
2557 if (!KnownNonNegative)
2560 case ICmpInst::ICMP_NE:
2561 case ICmpInst::ICMP_ULT:
2562 case ICmpInst::ICMP_ULE:
2563 return getTrue(ITy);
2567 // icmp pred X, (urem Y, X)
2568 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2569 bool KnownNonNegative, KnownNegative;
2573 case ICmpInst::ICMP_SGT:
2574 case ICmpInst::ICMP_SGE:
2575 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL,
2576 0, Q.AT, Q.CxtI, Q.DT);
2577 if (!KnownNonNegative)
2580 case ICmpInst::ICMP_NE:
2581 case ICmpInst::ICMP_UGT:
2582 case ICmpInst::ICMP_UGE:
2583 return getTrue(ITy);
2584 case ICmpInst::ICMP_SLT:
2585 case ICmpInst::ICMP_SLE:
2586 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL,
2587 0, Q.AT, Q.CxtI, Q.DT);
2588 if (!KnownNonNegative)
2591 case ICmpInst::ICMP_EQ:
2592 case ICmpInst::ICMP_ULT:
2593 case ICmpInst::ICMP_ULE:
2594 return getFalse(ITy);
2599 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2600 // icmp pred (X /u Y), X
2601 if (Pred == ICmpInst::ICMP_UGT)
2602 return getFalse(ITy);
2603 if (Pred == ICmpInst::ICMP_ULE)
2604 return getTrue(ITy);
2611 // where CI2 is a power of 2 and CI isn't
2612 if (auto *CI = dyn_cast<ConstantInt>(RHS)) {
2613 const APInt *CI2Val, *CIVal = &CI->getValue();
2614 if (LBO && match(LBO, m_Shl(m_APInt(CI2Val), m_Value())) &&
2615 CI2Val->isPowerOf2()) {
2616 if (!CIVal->isPowerOf2()) {
2617 // CI2 << X can equal zero in some circumstances,
2618 // this simplification is unsafe if CI is zero.
2620 // We know it is safe if:
2621 // - The shift is nsw, we can't shift out the one bit.
2622 // - The shift is nuw, we can't shift out the one bit.
2625 if (LBO->hasNoSignedWrap() || LBO->hasNoUnsignedWrap() ||
2626 *CI2Val == 1 || !CI->isZero()) {
2627 if (Pred == ICmpInst::ICMP_EQ)
2628 return ConstantInt::getFalse(RHS->getContext());
2629 if (Pred == ICmpInst::ICMP_NE)
2630 return ConstantInt::getTrue(RHS->getContext());
2633 if (CIVal->isSignBit() && *CI2Val == 1) {
2634 if (Pred == ICmpInst::ICMP_UGT)
2635 return ConstantInt::getFalse(RHS->getContext());
2636 if (Pred == ICmpInst::ICMP_ULE)
2637 return ConstantInt::getTrue(RHS->getContext());
2642 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2643 LBO->getOperand(1) == RBO->getOperand(1)) {
2644 switch (LBO->getOpcode()) {
2646 case Instruction::UDiv:
2647 case Instruction::LShr:
2648 if (ICmpInst::isSigned(Pred))
2651 case Instruction::SDiv:
2652 case Instruction::AShr:
2653 if (!LBO->isExact() || !RBO->isExact())
2655 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2656 RBO->getOperand(0), Q, MaxRecurse-1))
2659 case Instruction::Shl: {
2660 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2661 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2664 if (!NSW && ICmpInst::isSigned(Pred))
2666 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2667 RBO->getOperand(0), Q, MaxRecurse-1))
2674 // Simplify comparisons involving max/min.
2676 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2677 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2679 // Signed variants on "max(a,b)>=a -> true".
2680 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2681 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2682 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2683 // We analyze this as smax(A, B) pred A.
2685 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2686 (A == LHS || B == LHS)) {
2687 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2688 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2689 // We analyze this as smax(A, B) swapped-pred A.
2690 P = CmpInst::getSwappedPredicate(Pred);
2691 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2692 (A == RHS || B == RHS)) {
2693 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2694 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2695 // We analyze this as smax(-A, -B) swapped-pred -A.
2696 // Note that we do not need to actually form -A or -B thanks to EqP.
2697 P = CmpInst::getSwappedPredicate(Pred);
2698 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2699 (A == LHS || B == LHS)) {
2700 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2701 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2702 // We analyze this as smax(-A, -B) pred -A.
2703 // Note that we do not need to actually form -A or -B thanks to EqP.
2706 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2707 // Cases correspond to "max(A, B) p A".
2711 case CmpInst::ICMP_EQ:
2712 case CmpInst::ICMP_SLE:
2713 // Equivalent to "A EqP B". This may be the same as the condition tested
2714 // in the max/min; if so, we can just return that.
2715 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2717 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2719 // Otherwise, see if "A EqP B" simplifies.
2721 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2724 case CmpInst::ICMP_NE:
2725 case CmpInst::ICMP_SGT: {
2726 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2727 // Equivalent to "A InvEqP B". This may be the same as the condition
2728 // tested in the max/min; if so, we can just return that.
2729 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2731 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2733 // Otherwise, see if "A InvEqP B" simplifies.
2735 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2739 case CmpInst::ICMP_SGE:
2741 return getTrue(ITy);
2742 case CmpInst::ICMP_SLT:
2744 return getFalse(ITy);
2748 // Unsigned variants on "max(a,b)>=a -> true".
2749 P = CmpInst::BAD_ICMP_PREDICATE;
2750 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2751 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2752 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2753 // We analyze this as umax(A, B) pred A.
2755 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2756 (A == LHS || B == LHS)) {
2757 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2758 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2759 // We analyze this as umax(A, B) swapped-pred A.
2760 P = CmpInst::getSwappedPredicate(Pred);
2761 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2762 (A == RHS || B == RHS)) {
2763 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2764 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2765 // We analyze this as umax(-A, -B) swapped-pred -A.
2766 // Note that we do not need to actually form -A or -B thanks to EqP.
2767 P = CmpInst::getSwappedPredicate(Pred);
2768 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2769 (A == LHS || B == LHS)) {
2770 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2771 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2772 // We analyze this as umax(-A, -B) pred -A.
2773 // Note that we do not need to actually form -A or -B thanks to EqP.
2776 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2777 // Cases correspond to "max(A, B) p A".
2781 case CmpInst::ICMP_EQ:
2782 case CmpInst::ICMP_ULE:
2783 // Equivalent to "A EqP B". This may be the same as the condition tested
2784 // in the max/min; if so, we can just return that.
2785 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2787 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2789 // Otherwise, see if "A EqP B" simplifies.
2791 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2794 case CmpInst::ICMP_NE:
2795 case CmpInst::ICMP_UGT: {
2796 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2797 // Equivalent to "A InvEqP B". This may be the same as the condition
2798 // tested in the max/min; if so, we can just return that.
2799 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2801 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2803 // Otherwise, see if "A InvEqP B" simplifies.
2805 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2809 case CmpInst::ICMP_UGE:
2811 return getTrue(ITy);
2812 case CmpInst::ICMP_ULT:
2814 return getFalse(ITy);
2818 // Variants on "max(x,y) >= min(x,z)".
2820 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2821 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2822 (A == C || A == D || B == C || B == D)) {
2823 // max(x, ?) pred min(x, ?).
2824 if (Pred == CmpInst::ICMP_SGE)
2826 return getTrue(ITy);
2827 if (Pred == CmpInst::ICMP_SLT)
2829 return getFalse(ITy);
2830 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2831 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2832 (A == C || A == D || B == C || B == D)) {
2833 // min(x, ?) pred max(x, ?).
2834 if (Pred == CmpInst::ICMP_SLE)
2836 return getTrue(ITy);
2837 if (Pred == CmpInst::ICMP_SGT)
2839 return getFalse(ITy);
2840 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2841 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2842 (A == C || A == D || B == C || B == D)) {
2843 // max(x, ?) pred min(x, ?).
2844 if (Pred == CmpInst::ICMP_UGE)
2846 return getTrue(ITy);
2847 if (Pred == CmpInst::ICMP_ULT)
2849 return getFalse(ITy);
2850 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2851 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2852 (A == C || A == D || B == C || B == D)) {
2853 // min(x, ?) pred max(x, ?).
2854 if (Pred == CmpInst::ICMP_ULE)
2856 return getTrue(ITy);
2857 if (Pred == CmpInst::ICMP_UGT)
2859 return getFalse(ITy);
2862 // Simplify comparisons of related pointers using a powerful, recursive
2863 // GEP-walk when we have target data available..
2864 if (LHS->getType()->isPointerTy())
2865 if (Constant *C = computePointerICmp(Q.DL, Q.TLI, Pred, LHS, RHS))
2868 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
2869 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
2870 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
2871 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
2872 (ICmpInst::isEquality(Pred) ||
2873 (GLHS->isInBounds() && GRHS->isInBounds() &&
2874 Pred == ICmpInst::getSignedPredicate(Pred)))) {
2875 // The bases are equal and the indices are constant. Build a constant
2876 // expression GEP with the same indices and a null base pointer to see
2877 // what constant folding can make out of it.
2878 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
2879 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
2880 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS);
2882 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
2883 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS);
2884 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
2889 // If a bit is known to be zero for A and known to be one for B,
2890 // then A and B cannot be equal.
2891 if (ICmpInst::isEquality(Pred)) {
2892 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2893 uint32_t BitWidth = CI->getBitWidth();
2894 APInt LHSKnownZero(BitWidth, 0);
2895 APInt LHSKnownOne(BitWidth, 0);
2896 computeKnownBits(LHS, LHSKnownZero, LHSKnownOne, Q.DL, /*Depth=*/0, Q.AT,
2898 const APInt &RHSVal = CI->getValue();
2899 if (((LHSKnownZero & RHSVal) != 0) || ((LHSKnownOne & ~RHSVal) != 0))
2900 return Pred == ICmpInst::ICMP_EQ
2901 ? ConstantInt::getFalse(CI->getContext())
2902 : ConstantInt::getTrue(CI->getContext());
2906 // If the comparison is with the result of a select instruction, check whether
2907 // comparing with either branch of the select always yields the same value.
2908 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2909 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2912 // If the comparison is with the result of a phi instruction, check whether
2913 // doing the compare with each incoming phi value yields a common result.
2914 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2915 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2921 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2922 const DataLayout *DL,
2923 const TargetLibraryInfo *TLI,
2924 const DominatorTree *DT,
2925 AssumptionTracker *AT,
2926 Instruction *CxtI) {
2927 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (DL, TLI, DT, AT, CxtI),
2931 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
2932 /// fold the result. If not, this returns null.
2933 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2934 const Query &Q, unsigned MaxRecurse) {
2935 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2936 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
2938 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2939 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2940 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
2942 // If we have a constant, make sure it is on the RHS.
2943 std::swap(LHS, RHS);
2944 Pred = CmpInst::getSwappedPredicate(Pred);
2947 // Fold trivial predicates.
2948 if (Pred == FCmpInst::FCMP_FALSE)
2949 return ConstantInt::get(GetCompareTy(LHS), 0);
2950 if (Pred == FCmpInst::FCMP_TRUE)
2951 return ConstantInt::get(GetCompareTy(LHS), 1);
2953 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
2954 return UndefValue::get(GetCompareTy(LHS));
2956 // fcmp x,x -> true/false. Not all compares are foldable.
2958 if (CmpInst::isTrueWhenEqual(Pred))
2959 return ConstantInt::get(GetCompareTy(LHS), 1);
2960 if (CmpInst::isFalseWhenEqual(Pred))
2961 return ConstantInt::get(GetCompareTy(LHS), 0);
2964 // Handle fcmp with constant RHS
2965 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2966 // If the constant is a nan, see if we can fold the comparison based on it.
2967 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2968 if (CFP->getValueAPF().isNaN()) {
2969 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
2970 return ConstantInt::getFalse(CFP->getContext());
2971 assert(FCmpInst::isUnordered(Pred) &&
2972 "Comparison must be either ordered or unordered!");
2973 // True if unordered.
2974 return ConstantInt::getTrue(CFP->getContext());
2976 // Check whether the constant is an infinity.
2977 if (CFP->getValueAPF().isInfinity()) {
2978 if (CFP->getValueAPF().isNegative()) {
2980 case FCmpInst::FCMP_OLT:
2981 // No value is ordered and less than negative infinity.
2982 return ConstantInt::getFalse(CFP->getContext());
2983 case FCmpInst::FCMP_UGE:
2984 // All values are unordered with or at least negative infinity.
2985 return ConstantInt::getTrue(CFP->getContext());
2991 case FCmpInst::FCMP_OGT:
2992 // No value is ordered and greater than infinity.
2993 return ConstantInt::getFalse(CFP->getContext());
2994 case FCmpInst::FCMP_ULE:
2995 // All values are unordered with and at most infinity.
2996 return ConstantInt::getTrue(CFP->getContext());
3005 // If the comparison is with the result of a select instruction, check whether
3006 // comparing with either branch of the select always yields the same value.
3007 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3008 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3011 // If the comparison is with the result of a phi instruction, check whether
3012 // doing the compare with each incoming phi value yields a common result.
3013 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3014 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3020 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3021 const DataLayout *DL,
3022 const TargetLibraryInfo *TLI,
3023 const DominatorTree *DT,
3024 AssumptionTracker *AT,
3025 const Instruction *CxtI) {
3026 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (DL, TLI, DT, AT, CxtI),
3030 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
3031 /// the result. If not, this returns null.
3032 static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
3033 Value *FalseVal, const Query &Q,
3034 unsigned MaxRecurse) {
3035 // select true, X, Y -> X
3036 // select false, X, Y -> Y
3037 if (Constant *CB = dyn_cast<Constant>(CondVal)) {
3038 if (CB->isAllOnesValue())
3040 if (CB->isNullValue())
3044 // select C, X, X -> X
3045 if (TrueVal == FalseVal)
3048 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
3049 if (isa<Constant>(TrueVal))
3053 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
3055 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
3061 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3062 const DataLayout *DL,
3063 const TargetLibraryInfo *TLI,
3064 const DominatorTree *DT,
3065 AssumptionTracker *AT,
3066 const Instruction *CxtI) {
3067 return ::SimplifySelectInst(Cond, TrueVal, FalseVal,
3068 Query (DL, TLI, DT, AT, CxtI), RecursionLimit);
3071 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
3072 /// fold the result. If not, this returns null.
3073 static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) {
3074 // The type of the GEP pointer operand.
3075 PointerType *PtrTy = cast<PointerType>(Ops[0]->getType()->getScalarType());
3076 unsigned AS = PtrTy->getAddressSpace();
3078 // getelementptr P -> P.
3079 if (Ops.size() == 1)
3082 // Compute the (pointer) type returned by the GEP instruction.
3083 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
3084 Type *GEPTy = PointerType::get(LastType, AS);
3085 if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
3086 GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3088 if (isa<UndefValue>(Ops[0]))
3089 return UndefValue::get(GEPTy);
3091 if (Ops.size() == 2) {
3092 // getelementptr P, 0 -> P.
3093 if (match(Ops[1], m_Zero()))
3096 Type *Ty = PtrTy->getElementType();
3097 if (Q.DL && Ty->isSized()) {
3100 uint64_t TyAllocSize = Q.DL->getTypeAllocSize(Ty);
3101 // getelementptr P, N -> P if P points to a type of zero size.
3102 if (TyAllocSize == 0)
3105 // The following transforms are only safe if the ptrtoint cast
3106 // doesn't truncate the pointers.
3107 if (Ops[1]->getType()->getScalarSizeInBits() ==
3108 Q.DL->getPointerSizeInBits(AS)) {
3109 auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * {
3110 if (match(P, m_Zero()))
3111 return Constant::getNullValue(GEPTy);
3113 if (match(P, m_PtrToInt(m_Value(Temp))))
3114 if (Temp->getType() == GEPTy)
3119 // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
3120 if (TyAllocSize == 1 &&
3121 match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0])))))
3122 if (Value *R = PtrToIntOrZero(P))
3125 // getelementptr V, (ashr (sub P, V), C) -> Q
3126 // if P points to a type of size 1 << C.
3128 m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3129 m_ConstantInt(C))) &&
3130 TyAllocSize == 1ULL << C)
3131 if (Value *R = PtrToIntOrZero(P))
3134 // getelementptr V, (sdiv (sub P, V), C) -> Q
3135 // if P points to a type of size C.
3137 m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3138 m_SpecificInt(TyAllocSize))))
3139 if (Value *R = PtrToIntOrZero(P))
3145 // Check to see if this is constant foldable.
3146 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3147 if (!isa<Constant>(Ops[i]))
3150 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
3153 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const DataLayout *DL,
3154 const TargetLibraryInfo *TLI,
3155 const DominatorTree *DT, AssumptionTracker *AT,
3156 const Instruction *CxtI) {
3157 return ::SimplifyGEPInst(Ops, Query (DL, TLI, DT, AT, CxtI), RecursionLimit);
3160 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
3161 /// can fold the result. If not, this returns null.
3162 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
3163 ArrayRef<unsigned> Idxs, const Query &Q,
3165 if (Constant *CAgg = dyn_cast<Constant>(Agg))
3166 if (Constant *CVal = dyn_cast<Constant>(Val))
3167 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
3169 // insertvalue x, undef, n -> x
3170 if (match(Val, m_Undef()))
3173 // insertvalue x, (extractvalue y, n), n
3174 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
3175 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
3176 EV->getIndices() == Idxs) {
3177 // insertvalue undef, (extractvalue y, n), n -> y
3178 if (match(Agg, m_Undef()))
3179 return EV->getAggregateOperand();
3181 // insertvalue y, (extractvalue y, n), n -> y
3182 if (Agg == EV->getAggregateOperand())
3189 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
3190 ArrayRef<unsigned> Idxs,
3191 const DataLayout *DL,
3192 const TargetLibraryInfo *TLI,
3193 const DominatorTree *DT,
3194 AssumptionTracker *AT,
3195 const Instruction *CxtI) {
3196 return ::SimplifyInsertValueInst(Agg, Val, Idxs,
3197 Query (DL, TLI, DT, AT, CxtI),
3201 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
3202 static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
3203 // If all of the PHI's incoming values are the same then replace the PHI node
3204 // with the common value.
3205 Value *CommonValue = nullptr;
3206 bool HasUndefInput = false;
3207 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
3208 Value *Incoming = PN->getIncomingValue(i);
3209 // If the incoming value is the phi node itself, it can safely be skipped.
3210 if (Incoming == PN) continue;
3211 if (isa<UndefValue>(Incoming)) {
3212 // Remember that we saw an undef value, but otherwise ignore them.
3213 HasUndefInput = true;
3216 if (CommonValue && Incoming != CommonValue)
3217 return nullptr; // Not the same, bail out.
3218 CommonValue = Incoming;
3221 // If CommonValue is null then all of the incoming values were either undef or
3222 // equal to the phi node itself.
3224 return UndefValue::get(PN->getType());
3226 // If we have a PHI node like phi(X, undef, X), where X is defined by some
3227 // instruction, we cannot return X as the result of the PHI node unless it
3228 // dominates the PHI block.
3230 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr;
3235 static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) {
3236 if (Constant *C = dyn_cast<Constant>(Op))
3237 return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.DL, Q.TLI);
3242 Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const DataLayout *DL,
3243 const TargetLibraryInfo *TLI,
3244 const DominatorTree *DT,
3245 AssumptionTracker *AT,
3246 const Instruction *CxtI) {
3247 return ::SimplifyTruncInst(Op, Ty, Query (DL, TLI, DT, AT, CxtI),
3251 //=== Helper functions for higher up the class hierarchy.
3253 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
3254 /// fold the result. If not, this returns null.
3255 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
3256 const Query &Q, unsigned MaxRecurse) {
3258 case Instruction::Add:
3259 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3261 case Instruction::FAdd:
3262 return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3264 case Instruction::Sub:
3265 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3267 case Instruction::FSub:
3268 return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3270 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
3271 case Instruction::FMul:
3272 return SimplifyFMulInst (LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3273 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
3274 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
3275 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse);
3276 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
3277 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
3278 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse);
3279 case Instruction::Shl:
3280 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3282 case Instruction::LShr:
3283 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
3284 case Instruction::AShr:
3285 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
3286 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
3287 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
3288 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
3290 if (Constant *CLHS = dyn_cast<Constant>(LHS))
3291 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
3292 Constant *COps[] = {CLHS, CRHS};
3293 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.DL,
3297 // If the operation is associative, try some generic simplifications.
3298 if (Instruction::isAssociative(Opcode))
3299 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
3302 // If the operation is with the result of a select instruction check whether
3303 // operating on either branch of the select always yields the same value.
3304 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3305 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
3308 // If the operation is with the result of a phi instruction, check whether
3309 // operating on all incoming values of the phi always yields the same value.
3310 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3311 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
3318 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
3319 const DataLayout *DL, const TargetLibraryInfo *TLI,
3320 const DominatorTree *DT, AssumptionTracker *AT,
3321 const Instruction *CxtI) {
3322 return ::SimplifyBinOp(Opcode, LHS, RHS, Query (DL, TLI, DT, AT, CxtI),
3326 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
3327 /// fold the result.
3328 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3329 const Query &Q, unsigned MaxRecurse) {
3330 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
3331 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
3332 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
3335 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3336 const DataLayout *DL, const TargetLibraryInfo *TLI,
3337 const DominatorTree *DT, AssumptionTracker *AT,
3338 const Instruction *CxtI) {
3339 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (DL, TLI, DT, AT, CxtI),
3343 static bool IsIdempotent(Intrinsic::ID ID) {
3345 default: return false;
3347 // Unary idempotent: f(f(x)) = f(x)
3348 case Intrinsic::fabs:
3349 case Intrinsic::floor:
3350 case Intrinsic::ceil:
3351 case Intrinsic::trunc:
3352 case Intrinsic::rint:
3353 case Intrinsic::nearbyint:
3354 case Intrinsic::round:
3359 template <typename IterTy>
3360 static Value *SimplifyIntrinsic(Intrinsic::ID IID, IterTy ArgBegin, IterTy ArgEnd,
3361 const Query &Q, unsigned MaxRecurse) {
3362 // Perform idempotent optimizations
3363 if (!IsIdempotent(IID))
3367 if (std::distance(ArgBegin, ArgEnd) == 1)
3368 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin))
3369 if (II->getIntrinsicID() == IID)
3375 template <typename IterTy>
3376 static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd,
3377 const Query &Q, unsigned MaxRecurse) {
3378 Type *Ty = V->getType();
3379 if (PointerType *PTy = dyn_cast<PointerType>(Ty))
3380 Ty = PTy->getElementType();
3381 FunctionType *FTy = cast<FunctionType>(Ty);
3383 // call undef -> undef
3384 if (isa<UndefValue>(V))
3385 return UndefValue::get(FTy->getReturnType());
3387 Function *F = dyn_cast<Function>(V);
3391 if (unsigned IID = F->getIntrinsicID())
3393 SimplifyIntrinsic((Intrinsic::ID) IID, ArgBegin, ArgEnd, Q, MaxRecurse))
3396 if (!canConstantFoldCallTo(F))
3399 SmallVector<Constant *, 4> ConstantArgs;
3400 ConstantArgs.reserve(ArgEnd - ArgBegin);
3401 for (IterTy I = ArgBegin, E = ArgEnd; I != E; ++I) {
3402 Constant *C = dyn_cast<Constant>(*I);
3405 ConstantArgs.push_back(C);
3408 return ConstantFoldCall(F, ConstantArgs, Q.TLI);
3411 Value *llvm::SimplifyCall(Value *V, User::op_iterator ArgBegin,
3412 User::op_iterator ArgEnd, const DataLayout *DL,
3413 const TargetLibraryInfo *TLI,
3414 const DominatorTree *DT, AssumptionTracker *AT,
3415 const Instruction *CxtI) {
3416 return ::SimplifyCall(V, ArgBegin, ArgEnd, Query(DL, TLI, DT, AT, CxtI),
3420 Value *llvm::SimplifyCall(Value *V, ArrayRef<Value *> Args,
3421 const DataLayout *DL, const TargetLibraryInfo *TLI,
3422 const DominatorTree *DT, AssumptionTracker *AT,
3423 const Instruction *CxtI) {
3424 return ::SimplifyCall(V, Args.begin(), Args.end(),
3425 Query(DL, TLI, DT, AT, CxtI), RecursionLimit);
3428 /// SimplifyInstruction - See if we can compute a simplified version of this
3429 /// instruction. If not, this returns null.
3430 Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *DL,
3431 const TargetLibraryInfo *TLI,
3432 const DominatorTree *DT,
3433 AssumptionTracker *AT) {
3436 switch (I->getOpcode()) {
3438 Result = ConstantFoldInstruction(I, DL, TLI);
3440 case Instruction::FAdd:
3441 Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
3442 I->getFastMathFlags(), DL, TLI, DT, AT, I);
3444 case Instruction::Add:
3445 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
3446 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3447 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
3448 DL, TLI, DT, AT, I);
3450 case Instruction::FSub:
3451 Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
3452 I->getFastMathFlags(), DL, TLI, DT, AT, I);
3454 case Instruction::Sub:
3455 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
3456 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3457 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
3458 DL, TLI, DT, AT, I);
3460 case Instruction::FMul:
3461 Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1),
3462 I->getFastMathFlags(), DL, TLI, DT, AT, I);
3464 case Instruction::Mul:
3465 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1),
3466 DL, TLI, DT, AT, I);
3468 case Instruction::SDiv:
3469 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1),
3470 DL, TLI, DT, AT, I);
3472 case Instruction::UDiv:
3473 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1),
3474 DL, TLI, DT, AT, I);
3476 case Instruction::FDiv:
3477 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1),
3478 DL, TLI, DT, AT, I);
3480 case Instruction::SRem:
3481 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1),
3482 DL, TLI, DT, AT, I);
3484 case Instruction::URem:
3485 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1),
3486 DL, TLI, DT, AT, I);
3488 case Instruction::FRem:
3489 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1),
3490 DL, TLI, DT, AT, I);
3492 case Instruction::Shl:
3493 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
3494 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3495 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
3496 DL, TLI, DT, AT, I);
3498 case Instruction::LShr:
3499 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
3500 cast<BinaryOperator>(I)->isExact(),
3501 DL, TLI, DT, AT, I);
3503 case Instruction::AShr:
3504 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
3505 cast<BinaryOperator>(I)->isExact(),
3506 DL, TLI, DT, AT, I);
3508 case Instruction::And:
3509 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1),
3510 DL, TLI, DT, AT, I);
3512 case Instruction::Or:
3513 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3516 case Instruction::Xor:
3517 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1),
3518 DL, TLI, DT, AT, I);
3520 case Instruction::ICmp:
3521 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
3522 I->getOperand(0), I->getOperand(1),
3523 DL, TLI, DT, AT, I);
3525 case Instruction::FCmp:
3526 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
3527 I->getOperand(0), I->getOperand(1),
3528 DL, TLI, DT, AT, I);
3530 case Instruction::Select:
3531 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
3532 I->getOperand(2), DL, TLI, DT, AT, I);
3534 case Instruction::GetElementPtr: {
3535 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
3536 Result = SimplifyGEPInst(Ops, DL, TLI, DT, AT, I);
3539 case Instruction::InsertValue: {
3540 InsertValueInst *IV = cast<InsertValueInst>(I);
3541 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
3542 IV->getInsertedValueOperand(),
3543 IV->getIndices(), DL, TLI, DT, AT, I);
3546 case Instruction::PHI:
3547 Result = SimplifyPHINode(cast<PHINode>(I), Query (DL, TLI, DT, AT, I));
3549 case Instruction::Call: {
3550 CallSite CS(cast<CallInst>(I));
3551 Result = SimplifyCall(CS.getCalledValue(), CS.arg_begin(), CS.arg_end(),
3552 DL, TLI, DT, AT, I);
3555 case Instruction::Trunc:
3556 Result = SimplifyTruncInst(I->getOperand(0), I->getType(), DL, TLI, DT,
3561 /// If called on unreachable code, the above logic may report that the
3562 /// instruction simplified to itself. Make life easier for users by
3563 /// detecting that case here, returning a safe value instead.
3564 return Result == I ? UndefValue::get(I->getType()) : Result;
3567 /// \brief Implementation of recursive simplification through an instructions
3570 /// This is the common implementation of the recursive simplification routines.
3571 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
3572 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
3573 /// instructions to process and attempt to simplify it using
3574 /// InstructionSimplify.
3576 /// This routine returns 'true' only when *it* simplifies something. The passed
3577 /// in simplified value does not count toward this.
3578 static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
3579 const DataLayout *DL,
3580 const TargetLibraryInfo *TLI,
3581 const DominatorTree *DT,
3582 AssumptionTracker *AT) {
3583 bool Simplified = false;
3584 SmallSetVector<Instruction *, 8> Worklist;
3586 // If we have an explicit value to collapse to, do that round of the
3587 // simplification loop by hand initially.
3589 for (User *U : I->users())
3591 Worklist.insert(cast<Instruction>(U));
3593 // Replace the instruction with its simplified value.
3594 I->replaceAllUsesWith(SimpleV);
3596 // Gracefully handle edge cases where the instruction is not wired into any
3599 I->eraseFromParent();
3604 // Note that we must test the size on each iteration, the worklist can grow.
3605 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
3608 // See if this instruction simplifies.
3609 SimpleV = SimplifyInstruction(I, DL, TLI, DT, AT);
3615 // Stash away all the uses of the old instruction so we can check them for
3616 // recursive simplifications after a RAUW. This is cheaper than checking all
3617 // uses of To on the recursive step in most cases.
3618 for (User *U : I->users())
3619 Worklist.insert(cast<Instruction>(U));
3621 // Replace the instruction with its simplified value.
3622 I->replaceAllUsesWith(SimpleV);
3624 // Gracefully handle edge cases where the instruction is not wired into any
3627 I->eraseFromParent();
3632 bool llvm::recursivelySimplifyInstruction(Instruction *I,
3633 const DataLayout *DL,
3634 const TargetLibraryInfo *TLI,
3635 const DominatorTree *DT,
3636 AssumptionTracker *AT) {
3637 return replaceAndRecursivelySimplifyImpl(I, nullptr, DL, TLI, DT, AT);
3640 bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
3641 const DataLayout *DL,
3642 const TargetLibraryInfo *TLI,
3643 const DominatorTree *DT,
3644 AssumptionTracker *AT) {
3645 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
3646 assert(SimpleV && "Must provide a simplified value.");
3647 return replaceAndRecursivelySimplifyImpl(I, SimpleV, DL, TLI, DT, AT);