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 #define DEBUG_TYPE "instsimplify"
21 #include "llvm/GlobalAlias.h"
22 #include "llvm/Operator.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/Analysis/InstructionSimplify.h"
25 #include "llvm/Analysis/AliasAnalysis.h"
26 #include "llvm/Analysis/ConstantFolding.h"
27 #include "llvm/Analysis/Dominators.h"
28 #include "llvm/Analysis/ValueTracking.h"
29 #include "llvm/Support/ConstantRange.h"
30 #include "llvm/Support/GetElementPtrTypeIterator.h"
31 #include "llvm/Support/PatternMatch.h"
32 #include "llvm/Support/ValueHandle.h"
33 #include "llvm/Target/TargetData.h"
35 using namespace llvm::PatternMatch;
37 enum { RecursionLimit = 3 };
39 STATISTIC(NumExpand, "Number of expansions");
40 STATISTIC(NumFactor , "Number of factorizations");
41 STATISTIC(NumReassoc, "Number of reassociations");
45 const TargetLibraryInfo *TLI;
46 const DominatorTree *DT;
48 Query(const TargetData *td, const TargetLibraryInfo *tli,
49 const DominatorTree *dt) : TD(td), TLI(tli), DT(dt) {};
52 static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
53 static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
55 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
57 static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
58 static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
59 static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned);
61 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
62 /// a vector with every element false, as appropriate for the type.
63 static Constant *getFalse(Type *Ty) {
64 assert(Ty->getScalarType()->isIntegerTy(1) &&
65 "Expected i1 type or a vector of i1!");
66 return Constant::getNullValue(Ty);
69 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
70 /// a vector with every element true, as appropriate for the type.
71 static Constant *getTrue(Type *Ty) {
72 assert(Ty->getScalarType()->isIntegerTy(1) &&
73 "Expected i1 type or a vector of i1!");
74 return Constant::getAllOnesValue(Ty);
77 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
78 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
80 CmpInst *Cmp = dyn_cast<CmpInst>(V);
83 CmpInst::Predicate CPred = Cmp->getPredicate();
84 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
85 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
87 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
91 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
92 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
93 Instruction *I = dyn_cast<Instruction>(V);
95 // Arguments and constants dominate all instructions.
98 // If we are processing instructions (and/or basic blocks) that have not been
99 // fully added to a function, the parent nodes may still be null. Simply
100 // return the conservative answer in these cases.
101 if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
104 // If we have a DominatorTree then do a precise test.
106 if (!DT->isReachableFromEntry(P->getParent()))
108 if (!DT->isReachableFromEntry(I->getParent()))
110 return DT->dominates(I, P);
113 // Otherwise, if the instruction is in the entry block, and is not an invoke,
114 // then it obviously dominates all phi nodes.
115 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
122 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
123 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
124 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
125 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
126 /// Returns the simplified value, or null if no simplification was performed.
127 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
128 unsigned OpcToExpand, const Query &Q,
129 unsigned MaxRecurse) {
130 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
131 // Recursion is always used, so bail out at once if we already hit the limit.
135 // Check whether the expression has the form "(A op' B) op C".
136 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
137 if (Op0->getOpcode() == OpcodeToExpand) {
138 // It does! Try turning it into "(A op C) op' (B op C)".
139 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
140 // Do "A op C" and "B op C" both simplify?
141 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
142 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
143 // They do! Return "L op' R" if it simplifies or is already available.
144 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
145 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
146 && L == B && R == A)) {
150 // Otherwise return "L op' R" if it simplifies.
151 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
158 // Check whether the expression has the form "A op (B op' C)".
159 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
160 if (Op1->getOpcode() == OpcodeToExpand) {
161 // It does! Try turning it into "(A op B) op' (A op C)".
162 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
163 // Do "A op B" and "A op C" both simplify?
164 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
165 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
166 // They do! Return "L op' R" if it simplifies or is already available.
167 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
168 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
169 && L == C && R == B)) {
173 // Otherwise return "L op' R" if it simplifies.
174 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
184 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
185 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
186 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
187 /// Returns the simplified value, or null if no simplification was performed.
188 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
189 unsigned OpcToExtract, const Query &Q,
190 unsigned MaxRecurse) {
191 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
192 // Recursion is always used, so bail out at once if we already hit the limit.
196 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
197 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
199 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
200 !Op1 || Op1->getOpcode() != OpcodeToExtract)
203 // The expression has the form "(A op' B) op (C op' D)".
204 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
205 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
207 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
208 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
209 // commutative case, "(A op' B) op (C op' A)"?
210 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
211 Value *DD = A == C ? D : C;
212 // Form "A op' (B op DD)" if it simplifies completely.
213 // Does "B op DD" simplify?
214 if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) {
215 // It does! Return "A op' V" if it simplifies or is already available.
216 // If V equals B then "A op' V" is just the LHS. If V equals DD then
217 // "A op' V" is just the RHS.
218 if (V == B || V == DD) {
220 return V == B ? LHS : RHS;
222 // Otherwise return "A op' V" if it simplifies.
223 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) {
230 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
231 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
232 // commutative case, "(A op' B) op (B op' D)"?
233 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
234 Value *CC = B == D ? C : D;
235 // Form "(A op CC) op' B" if it simplifies completely..
236 // Does "A op CC" simplify?
237 if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) {
238 // It does! Return "V op' B" if it simplifies or is already available.
239 // If V equals A then "V op' B" is just the LHS. If V equals CC then
240 // "V op' B" is just the RHS.
241 if (V == A || V == CC) {
243 return V == A ? LHS : RHS;
245 // Otherwise return "V op' B" if it simplifies.
246 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) {
256 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
257 /// operations. Returns the simpler value, or null if none was found.
258 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
259 const Query &Q, unsigned MaxRecurse) {
260 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
261 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
263 // Recursion is always used, so bail out at once if we already hit the limit.
267 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
268 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
270 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
271 if (Op0 && Op0->getOpcode() == Opcode) {
272 Value *A = Op0->getOperand(0);
273 Value *B = Op0->getOperand(1);
276 // Does "B op C" simplify?
277 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
278 // It does! Return "A op V" if it simplifies or is already available.
279 // If V equals B then "A op V" is just the LHS.
280 if (V == B) return LHS;
281 // Otherwise return "A op V" if it simplifies.
282 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
289 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
290 if (Op1 && Op1->getOpcode() == Opcode) {
292 Value *B = Op1->getOperand(0);
293 Value *C = Op1->getOperand(1);
295 // Does "A op B" simplify?
296 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
297 // It does! Return "V op C" if it simplifies or is already available.
298 // If V equals B then "V op C" is just the RHS.
299 if (V == B) return RHS;
300 // Otherwise return "V op C" if it simplifies.
301 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
308 // The remaining transforms require commutativity as well as associativity.
309 if (!Instruction::isCommutative(Opcode))
312 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
313 if (Op0 && Op0->getOpcode() == Opcode) {
314 Value *A = Op0->getOperand(0);
315 Value *B = Op0->getOperand(1);
318 // Does "C op A" simplify?
319 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
320 // It does! Return "V op B" if it simplifies or is already available.
321 // If V equals A then "V op B" is just the LHS.
322 if (V == A) return LHS;
323 // Otherwise return "V op B" if it simplifies.
324 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
331 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
332 if (Op1 && Op1->getOpcode() == Opcode) {
334 Value *B = Op1->getOperand(0);
335 Value *C = Op1->getOperand(1);
337 // Does "C op A" simplify?
338 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
339 // It does! Return "B op V" if it simplifies or is already available.
340 // If V equals C then "B op V" is just the RHS.
341 if (V == C) return RHS;
342 // Otherwise return "B op V" if it simplifies.
343 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
353 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
354 /// instruction as an operand, try to simplify the binop by seeing whether
355 /// evaluating it on both branches of the select results in the same value.
356 /// Returns the common value if so, otherwise returns null.
357 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
358 const Query &Q, unsigned MaxRecurse) {
359 // Recursion is always used, so bail out at once if we already hit the limit.
364 if (isa<SelectInst>(LHS)) {
365 SI = cast<SelectInst>(LHS);
367 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
368 SI = cast<SelectInst>(RHS);
371 // Evaluate the BinOp on the true and false branches of the select.
375 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
376 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
378 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
379 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
382 // If they simplified to the same value, then return the common value.
383 // If they both failed to simplify then return null.
387 // If one branch simplified to undef, return the other one.
388 if (TV && isa<UndefValue>(TV))
390 if (FV && isa<UndefValue>(FV))
393 // If applying the operation did not change the true and false select values,
394 // then the result of the binop is the select itself.
395 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
398 // If one branch simplified and the other did not, and the simplified
399 // value is equal to the unsimplified one, return the simplified value.
400 // For example, select (cond, X, X & Z) & Z -> X & Z.
401 if ((FV && !TV) || (TV && !FV)) {
402 // Check that the simplified value has the form "X op Y" where "op" is the
403 // same as the original operation.
404 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
405 if (Simplified && Simplified->getOpcode() == Opcode) {
406 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
407 // We already know that "op" is the same as for the simplified value. See
408 // if the operands match too. If so, return the simplified value.
409 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
410 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
411 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
412 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
413 Simplified->getOperand(1) == UnsimplifiedRHS)
415 if (Simplified->isCommutative() &&
416 Simplified->getOperand(1) == UnsimplifiedLHS &&
417 Simplified->getOperand(0) == UnsimplifiedRHS)
425 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
426 /// try to simplify the comparison by seeing whether both branches of the select
427 /// result in the same value. Returns the common value if so, otherwise returns
429 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
430 Value *RHS, const Query &Q,
431 unsigned MaxRecurse) {
432 // Recursion is always used, so bail out at once if we already hit the limit.
436 // Make sure the select is on the LHS.
437 if (!isa<SelectInst>(LHS)) {
439 Pred = CmpInst::getSwappedPredicate(Pred);
441 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
442 SelectInst *SI = cast<SelectInst>(LHS);
443 Value *Cond = SI->getCondition();
444 Value *TV = SI->getTrueValue();
445 Value *FV = SI->getFalseValue();
447 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
448 // Does "cmp TV, RHS" simplify?
449 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
451 // It not only simplified, it simplified to the select condition. Replace
453 TCmp = getTrue(Cond->getType());
455 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
456 // condition then we can replace it with 'true'. Otherwise give up.
457 if (!isSameCompare(Cond, Pred, TV, RHS))
459 TCmp = getTrue(Cond->getType());
462 // Does "cmp FV, RHS" simplify?
463 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
465 // It not only simplified, it simplified to the select condition. Replace
467 FCmp = getFalse(Cond->getType());
469 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
470 // condition then we can replace it with 'false'. Otherwise give up.
471 if (!isSameCompare(Cond, Pred, FV, RHS))
473 FCmp = getFalse(Cond->getType());
476 // If both sides simplified to the same value, then use it as the result of
477 // the original comparison.
481 // The remaining cases only make sense if the select condition has the same
482 // type as the result of the comparison, so bail out if this is not so.
483 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
485 // If the false value simplified to false, then the result of the compare
486 // is equal to "Cond && TCmp". This also catches the case when the false
487 // value simplified to false and the true value to true, returning "Cond".
488 if (match(FCmp, m_Zero()))
489 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
491 // If the true value simplified to true, then the result of the compare
492 // is equal to "Cond || FCmp".
493 if (match(TCmp, m_One()))
494 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
496 // Finally, if the false value simplified to true and the true value to
497 // false, then the result of the compare is equal to "!Cond".
498 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
500 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
507 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
508 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
509 /// it on the incoming phi values yields the same result for every value. If so
510 /// returns the common value, otherwise returns null.
511 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
512 const Query &Q, unsigned MaxRecurse) {
513 // Recursion is always used, so bail out at once if we already hit the limit.
518 if (isa<PHINode>(LHS)) {
519 PI = cast<PHINode>(LHS);
520 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
521 if (!ValueDominatesPHI(RHS, PI, Q.DT))
524 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
525 PI = cast<PHINode>(RHS);
526 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
527 if (!ValueDominatesPHI(LHS, PI, Q.DT))
531 // Evaluate the BinOp on the incoming phi values.
532 Value *CommonValue = 0;
533 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
534 Value *Incoming = PI->getIncomingValue(i);
535 // If the incoming value is the phi node itself, it can safely be skipped.
536 if (Incoming == PI) continue;
537 Value *V = PI == LHS ?
538 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
539 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
540 // If the operation failed to simplify, or simplified to a different value
541 // to previously, then give up.
542 if (!V || (CommonValue && V != CommonValue))
550 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
551 /// try to simplify the comparison by seeing whether comparing with all of the
552 /// incoming phi values yields the same result every time. If so returns the
553 /// common result, otherwise returns null.
554 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
555 const Query &Q, unsigned MaxRecurse) {
556 // Recursion is always used, so bail out at once if we already hit the limit.
560 // Make sure the phi is on the LHS.
561 if (!isa<PHINode>(LHS)) {
563 Pred = CmpInst::getSwappedPredicate(Pred);
565 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
566 PHINode *PI = cast<PHINode>(LHS);
568 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
569 if (!ValueDominatesPHI(RHS, PI, Q.DT))
572 // Evaluate the BinOp on the incoming phi values.
573 Value *CommonValue = 0;
574 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
575 Value *Incoming = PI->getIncomingValue(i);
576 // If the incoming value is the phi node itself, it can safely be skipped.
577 if (Incoming == PI) continue;
578 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
579 // If the operation failed to simplify, or simplified to a different value
580 // to previously, then give up.
581 if (!V || (CommonValue && V != CommonValue))
589 /// SimplifyAddInst - Given operands for an Add, see if we can
590 /// fold the result. If not, this returns null.
591 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
592 const Query &Q, unsigned MaxRecurse) {
593 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
594 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
595 Constant *Ops[] = { CLHS, CRHS };
596 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops,
600 // Canonicalize the constant to the RHS.
604 // X + undef -> undef
605 if (match(Op1, m_Undef()))
609 if (match(Op1, m_Zero()))
616 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
617 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
620 // X + ~X -> -1 since ~X = -X-1
621 if (match(Op0, m_Not(m_Specific(Op1))) ||
622 match(Op1, m_Not(m_Specific(Op0))))
623 return Constant::getAllOnesValue(Op0->getType());
626 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
627 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
630 // Try some generic simplifications for associative operations.
631 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
635 // Mul distributes over Add. Try some generic simplifications based on this.
636 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
640 // Threading Add over selects and phi nodes is pointless, so don't bother.
641 // Threading over the select in "A + select(cond, B, C)" means evaluating
642 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
643 // only if B and C are equal. If B and C are equal then (since we assume
644 // that operands have already been simplified) "select(cond, B, C)" should
645 // have been simplified to the common value of B and C already. Analysing
646 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
647 // for threading over phi nodes.
652 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
653 const TargetData *TD, const TargetLibraryInfo *TLI,
654 const DominatorTree *DT) {
655 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
659 /// \brief Accumulate the constant integer offset a GEP represents.
661 /// Given a getelementptr instruction/constantexpr, accumulate the constant
662 /// offset from the base pointer into the provided APInt 'Offset'. Returns true
663 /// if the GEP has all-constant indices. Returns false if any non-constant
664 /// index is encountered leaving the 'Offset' in an undefined state. The
665 /// 'Offset' APInt must be the bitwidth of the target's pointer size.
666 static bool accumulateGEPOffset(const TargetData &TD, GEPOperator *GEP,
668 unsigned IntPtrWidth = TD.getPointerSizeInBits();
669 assert(IntPtrWidth == Offset.getBitWidth());
671 gep_type_iterator GTI = gep_type_begin(GEP);
672 for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end(); I != E;
674 ConstantInt *OpC = dyn_cast<ConstantInt>(*I);
675 if (!OpC) return false;
676 if (OpC->isZero()) continue;
678 // Handle a struct index, which adds its field offset to the pointer.
679 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
680 unsigned ElementIdx = OpC->getZExtValue();
681 const StructLayout *SL = TD.getStructLayout(STy);
682 Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
686 APInt TypeSize(IntPtrWidth, TD.getTypeAllocSize(GTI.getIndexedType()));
687 Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
692 /// \brief Compute the base pointer and cumulative constant offsets for V.
694 /// This strips all constant offsets off of V, leaving it the base pointer, and
695 /// accumulates the total constant offset applied in the returned constant. It
696 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
697 /// no constant offsets applied.
698 static Constant *stripAndComputeConstantOffsets(const TargetData &TD,
700 if (!V->getType()->isPointerTy())
703 unsigned IntPtrWidth = TD.getPointerSizeInBits();
704 APInt Offset = APInt::getNullValue(IntPtrWidth);
706 // Even though we don't look through PHI nodes, we could be called on an
707 // instruction in an unreachable block, which may be on a cycle.
708 SmallPtrSet<Value *, 4> Visited;
711 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
712 if (!accumulateGEPOffset(TD, GEP, Offset))
714 V = GEP->getPointerOperand();
715 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
716 V = cast<Operator>(V)->getOperand(0);
717 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
718 if (GA->mayBeOverridden())
720 V = GA->getAliasee();
724 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
725 } while (Visited.insert(V));
727 Type *IntPtrTy = TD.getIntPtrType(V->getContext());
728 return ConstantInt::get(IntPtrTy, Offset);
731 /// \brief Compute the constant difference between two pointer values.
732 /// If the difference is not a constant, returns zero.
733 static Constant *computePointerDifference(const TargetData &TD,
734 Value *LHS, Value *RHS) {
735 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
738 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
742 // If LHS and RHS are not related via constant offsets to the same base
743 // value, there is nothing we can do here.
747 // Otherwise, the difference of LHS - RHS can be computed as:
749 // = (LHSOffset + Base) - (RHSOffset + Base)
750 // = LHSOffset - RHSOffset
751 return ConstantExpr::getSub(LHSOffset, RHSOffset);
754 /// SimplifySubInst - Given operands for a Sub, see if we can
755 /// fold the result. If not, this returns null.
756 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
757 const Query &Q, unsigned MaxRecurse) {
758 if (Constant *CLHS = dyn_cast<Constant>(Op0))
759 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
760 Constant *Ops[] = { CLHS, CRHS };
761 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
765 // X - undef -> undef
766 // undef - X -> undef
767 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
768 return UndefValue::get(Op0->getType());
771 if (match(Op1, m_Zero()))
776 return Constant::getNullValue(Op0->getType());
781 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
782 match(Op0, m_Shl(m_Specific(Op1), m_One())))
785 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
786 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
787 Value *Y = 0, *Z = Op1;
788 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
789 // See if "V === Y - Z" simplifies.
790 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
791 // It does! Now see if "X + V" simplifies.
792 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
793 // It does, we successfully reassociated!
797 // See if "V === X - Z" simplifies.
798 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
799 // It does! Now see if "Y + V" simplifies.
800 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
801 // It does, we successfully reassociated!
807 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
808 // For example, X - (X + 1) -> -1
810 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
811 // See if "V === X - Y" simplifies.
812 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
813 // It does! Now see if "V - Z" simplifies.
814 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
815 // It does, we successfully reassociated!
819 // See if "V === X - Z" simplifies.
820 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
821 // It does! Now see if "V - Y" simplifies.
822 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
823 // It does, we successfully reassociated!
829 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
830 // For example, X - (X - Y) -> Y.
832 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
833 // See if "V === Z - X" simplifies.
834 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
835 // It does! Now see if "V + Y" simplifies.
836 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
837 // It does, we successfully reassociated!
842 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
843 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
844 match(Op1, m_Trunc(m_Value(Y))))
845 if (X->getType() == Y->getType())
846 // See if "V === X - Y" simplifies.
847 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
848 // It does! Now see if "trunc V" simplifies.
849 if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1))
850 // It does, return the simplified "trunc V".
853 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
854 if (Q.TD && match(Op0, m_PtrToInt(m_Value(X))) &&
855 match(Op1, m_PtrToInt(m_Value(Y))))
856 if (Constant *Result = computePointerDifference(*Q.TD, X, Y))
857 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
859 // Mul distributes over Sub. Try some generic simplifications based on this.
860 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
865 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
866 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
869 // Threading Sub over selects and phi nodes is pointless, so don't bother.
870 // Threading over the select in "A - select(cond, B, C)" means evaluating
871 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
872 // only if B and C are equal. If B and C are equal then (since we assume
873 // that operands have already been simplified) "select(cond, B, C)" should
874 // have been simplified to the common value of B and C already. Analysing
875 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
876 // for threading over phi nodes.
881 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
882 const TargetData *TD, const TargetLibraryInfo *TLI,
883 const DominatorTree *DT) {
884 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
888 /// SimplifyMulInst - Given operands for a Mul, see if we can
889 /// fold the result. If not, this returns null.
890 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
891 unsigned MaxRecurse) {
892 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
893 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
894 Constant *Ops[] = { CLHS, CRHS };
895 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
899 // Canonicalize the constant to the RHS.
904 if (match(Op1, m_Undef()))
905 return Constant::getNullValue(Op0->getType());
908 if (match(Op1, m_Zero()))
912 if (match(Op1, m_One()))
915 // (X / Y) * Y -> X if the division is exact.
917 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
918 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
922 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
923 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
926 // Try some generic simplifications for associative operations.
927 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
931 // Mul distributes over Add. Try some generic simplifications based on this.
932 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
936 // If the operation is with the result of a select instruction, check whether
937 // operating on either branch of the select always yields the same value.
938 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
939 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
943 // If the operation is with the result of a phi instruction, check whether
944 // operating on all incoming values of the phi always yields the same value.
945 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
946 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
953 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
954 const TargetLibraryInfo *TLI,
955 const DominatorTree *DT) {
956 return ::SimplifyMulInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
959 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
960 /// fold the result. If not, this returns null.
961 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
962 const Query &Q, unsigned MaxRecurse) {
963 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
964 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
965 Constant *Ops[] = { C0, C1 };
966 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
970 bool isSigned = Opcode == Instruction::SDiv;
972 // X / undef -> undef
973 if (match(Op1, m_Undef()))
977 if (match(Op0, m_Undef()))
978 return Constant::getNullValue(Op0->getType());
980 // 0 / X -> 0, we don't need to preserve faults!
981 if (match(Op0, m_Zero()))
985 if (match(Op1, m_One()))
988 if (Op0->getType()->isIntegerTy(1))
989 // It can't be division by zero, hence it must be division by one.
994 return ConstantInt::get(Op0->getType(), 1);
996 // (X * Y) / Y -> X if the multiplication does not overflow.
997 Value *X = 0, *Y = 0;
998 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
999 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
1000 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
1001 // If the Mul knows it does not overflow, then we are good to go.
1002 if ((isSigned && Mul->hasNoSignedWrap()) ||
1003 (!isSigned && Mul->hasNoUnsignedWrap()))
1005 // If X has the form X = A / Y then X * Y cannot overflow.
1006 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
1007 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1011 // (X rem Y) / Y -> 0
1012 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1013 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1014 return Constant::getNullValue(Op0->getType());
1016 // If the operation is with the result of a select instruction, check whether
1017 // operating on either branch of the select always yields the same value.
1018 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1019 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1022 // If the operation is with the result of a phi instruction, check whether
1023 // operating on all incoming values of the phi always yields the same value.
1024 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1025 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1031 /// SimplifySDivInst - Given operands for an SDiv, see if we can
1032 /// fold the result. If not, this returns null.
1033 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
1034 unsigned MaxRecurse) {
1035 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
1041 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1042 const TargetLibraryInfo *TLI,
1043 const DominatorTree *DT) {
1044 return ::SimplifySDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1047 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
1048 /// fold the result. If not, this returns null.
1049 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
1050 unsigned MaxRecurse) {
1051 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
1057 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1058 const TargetLibraryInfo *TLI,
1059 const DominatorTree *DT) {
1060 return ::SimplifyUDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1063 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q,
1065 // undef / X -> undef (the undef could be a snan).
1066 if (match(Op0, m_Undef()))
1069 // X / undef -> undef
1070 if (match(Op1, m_Undef()))
1076 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1077 const TargetLibraryInfo *TLI,
1078 const DominatorTree *DT) {
1079 return ::SimplifyFDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1082 /// SimplifyRem - Given operands for an SRem or URem, see if we can
1083 /// fold the result. If not, this returns null.
1084 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1085 const Query &Q, unsigned MaxRecurse) {
1086 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1087 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1088 Constant *Ops[] = { C0, C1 };
1089 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
1093 // X % undef -> undef
1094 if (match(Op1, m_Undef()))
1098 if (match(Op0, m_Undef()))
1099 return Constant::getNullValue(Op0->getType());
1101 // 0 % X -> 0, we don't need to preserve faults!
1102 if (match(Op0, m_Zero()))
1105 // X % 0 -> undef, we don't need to preserve faults!
1106 if (match(Op1, m_Zero()))
1107 return UndefValue::get(Op0->getType());
1110 if (match(Op1, m_One()))
1111 return Constant::getNullValue(Op0->getType());
1113 if (Op0->getType()->isIntegerTy(1))
1114 // It can't be remainder by zero, hence it must be remainder by one.
1115 return Constant::getNullValue(Op0->getType());
1119 return Constant::getNullValue(Op0->getType());
1121 // If the operation is with the result of a select instruction, check whether
1122 // operating on either branch of the select always yields the same value.
1123 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1124 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1127 // If the operation is with the result of a phi instruction, check whether
1128 // operating on all incoming values of the phi always yields the same value.
1129 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1130 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1136 /// SimplifySRemInst - Given operands for an SRem, see if we can
1137 /// fold the result. If not, this returns null.
1138 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
1139 unsigned MaxRecurse) {
1140 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
1146 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1147 const TargetLibraryInfo *TLI,
1148 const DominatorTree *DT) {
1149 return ::SimplifySRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1152 /// SimplifyURemInst - Given operands for a URem, see if we can
1153 /// fold the result. If not, this returns null.
1154 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
1155 unsigned MaxRecurse) {
1156 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
1162 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1163 const TargetLibraryInfo *TLI,
1164 const DominatorTree *DT) {
1165 return ::SimplifyURemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1168 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &,
1170 // undef % X -> undef (the undef could be a snan).
1171 if (match(Op0, m_Undef()))
1174 // X % undef -> undef
1175 if (match(Op1, m_Undef()))
1181 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1182 const TargetLibraryInfo *TLI,
1183 const DominatorTree *DT) {
1184 return ::SimplifyFRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1187 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1188 /// fold the result. If not, this returns null.
1189 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1190 const Query &Q, unsigned MaxRecurse) {
1191 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1192 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1193 Constant *Ops[] = { C0, C1 };
1194 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
1198 // 0 shift by X -> 0
1199 if (match(Op0, m_Zero()))
1202 // X shift by 0 -> X
1203 if (match(Op1, m_Zero()))
1206 // X shift by undef -> undef because it may shift by the bitwidth.
1207 if (match(Op1, m_Undef()))
1210 // Shifting by the bitwidth or more is undefined.
1211 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
1212 if (CI->getValue().getLimitedValue() >=
1213 Op0->getType()->getScalarSizeInBits())
1214 return UndefValue::get(Op0->getType());
1216 // If the operation is with the result of a select instruction, check whether
1217 // operating on either branch of the select always yields the same value.
1218 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1219 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1222 // If the operation is with the result of a phi instruction, check whether
1223 // operating on all incoming values of the phi always yields the same value.
1224 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1225 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1231 /// SimplifyShlInst - Given operands for an Shl, see if we can
1232 /// fold the result. If not, this returns null.
1233 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1234 const Query &Q, unsigned MaxRecurse) {
1235 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1239 if (match(Op0, m_Undef()))
1240 return Constant::getNullValue(Op0->getType());
1242 // (X >> A) << A -> X
1244 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1249 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1250 const TargetData *TD, const TargetLibraryInfo *TLI,
1251 const DominatorTree *DT) {
1252 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
1256 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1257 /// fold the result. If not, this returns null.
1258 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1259 const Query &Q, unsigned MaxRecurse) {
1260 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse))
1264 if (match(Op0, m_Undef()))
1265 return Constant::getNullValue(Op0->getType());
1267 // (X << A) >> A -> X
1269 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1270 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
1276 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1277 const TargetData *TD,
1278 const TargetLibraryInfo *TLI,
1279 const DominatorTree *DT) {
1280 return ::SimplifyLShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
1284 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1285 /// fold the result. If not, this returns null.
1286 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1287 const Query &Q, unsigned MaxRecurse) {
1288 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse))
1291 // all ones >>a X -> all ones
1292 if (match(Op0, m_AllOnes()))
1295 // undef >>a X -> all ones
1296 if (match(Op0, m_Undef()))
1297 return Constant::getAllOnesValue(Op0->getType());
1299 // (X << A) >> A -> X
1301 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1302 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
1308 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1309 const TargetData *TD,
1310 const TargetLibraryInfo *TLI,
1311 const DominatorTree *DT) {
1312 return ::SimplifyAShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
1316 /// SimplifyAndInst - Given operands for an And, see if we can
1317 /// fold the result. If not, this returns null.
1318 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
1319 unsigned MaxRecurse) {
1320 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1321 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1322 Constant *Ops[] = { CLHS, CRHS };
1323 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1327 // Canonicalize the constant to the RHS.
1328 std::swap(Op0, Op1);
1332 if (match(Op1, m_Undef()))
1333 return Constant::getNullValue(Op0->getType());
1340 if (match(Op1, m_Zero()))
1344 if (match(Op1, m_AllOnes()))
1347 // A & ~A = ~A & A = 0
1348 if (match(Op0, m_Not(m_Specific(Op1))) ||
1349 match(Op1, m_Not(m_Specific(Op0))))
1350 return Constant::getNullValue(Op0->getType());
1353 Value *A = 0, *B = 0;
1354 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1355 (A == Op1 || B == Op1))
1359 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1360 (A == Op0 || B == Op0))
1363 // A & (-A) = A if A is a power of two or zero.
1364 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1365 match(Op1, m_Neg(m_Specific(Op0)))) {
1366 if (isPowerOfTwo(Op0, Q.TD, /*OrZero*/true))
1368 if (isPowerOfTwo(Op1, Q.TD, /*OrZero*/true))
1372 // Try some generic simplifications for associative operations.
1373 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1377 // And distributes over Or. Try some generic simplifications based on this.
1378 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1382 // And distributes over Xor. Try some generic simplifications based on this.
1383 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1387 // Or distributes over And. Try some generic simplifications based on this.
1388 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1392 // If the operation is with the result of a select instruction, check whether
1393 // operating on either branch of the select always yields the same value.
1394 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1395 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1399 // If the operation is with the result of a phi instruction, check whether
1400 // operating on all incoming values of the phi always yields the same value.
1401 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1402 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1409 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1410 const TargetLibraryInfo *TLI,
1411 const DominatorTree *DT) {
1412 return ::SimplifyAndInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1415 /// SimplifyOrInst - Given operands for an Or, see if we can
1416 /// fold the result. If not, this returns null.
1417 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
1418 unsigned MaxRecurse) {
1419 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1420 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1421 Constant *Ops[] = { CLHS, CRHS };
1422 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1426 // Canonicalize the constant to the RHS.
1427 std::swap(Op0, Op1);
1431 if (match(Op1, m_Undef()))
1432 return Constant::getAllOnesValue(Op0->getType());
1439 if (match(Op1, m_Zero()))
1443 if (match(Op1, m_AllOnes()))
1446 // A | ~A = ~A | A = -1
1447 if (match(Op0, m_Not(m_Specific(Op1))) ||
1448 match(Op1, m_Not(m_Specific(Op0))))
1449 return Constant::getAllOnesValue(Op0->getType());
1452 Value *A = 0, *B = 0;
1453 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1454 (A == Op1 || B == Op1))
1458 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1459 (A == Op0 || B == Op0))
1462 // ~(A & ?) | A = -1
1463 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1464 (A == Op1 || B == Op1))
1465 return Constant::getAllOnesValue(Op1->getType());
1467 // A | ~(A & ?) = -1
1468 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1469 (A == Op0 || B == Op0))
1470 return Constant::getAllOnesValue(Op0->getType());
1472 // Try some generic simplifications for associative operations.
1473 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1477 // Or distributes over And. Try some generic simplifications based on this.
1478 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1482 // And distributes over Or. Try some generic simplifications based on this.
1483 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1487 // If the operation is with the result of a select instruction, check whether
1488 // operating on either branch of the select always yields the same value.
1489 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1490 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1494 // If the operation is with the result of a phi instruction, check whether
1495 // operating on all incoming values of the phi always yields the same value.
1496 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1497 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1503 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1504 const TargetLibraryInfo *TLI,
1505 const DominatorTree *DT) {
1506 return ::SimplifyOrInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1509 /// SimplifyXorInst - Given operands for a Xor, see if we can
1510 /// fold the result. If not, this returns null.
1511 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q,
1512 unsigned MaxRecurse) {
1513 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1514 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1515 Constant *Ops[] = { CLHS, CRHS };
1516 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1520 // Canonicalize the constant to the RHS.
1521 std::swap(Op0, Op1);
1524 // A ^ undef -> undef
1525 if (match(Op1, m_Undef()))
1529 if (match(Op1, m_Zero()))
1534 return Constant::getNullValue(Op0->getType());
1536 // A ^ ~A = ~A ^ A = -1
1537 if (match(Op0, m_Not(m_Specific(Op1))) ||
1538 match(Op1, m_Not(m_Specific(Op0))))
1539 return Constant::getAllOnesValue(Op0->getType());
1541 // Try some generic simplifications for associative operations.
1542 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1546 // And distributes over Xor. Try some generic simplifications based on this.
1547 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1551 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1552 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1553 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1554 // only if B and C are equal. If B and C are equal then (since we assume
1555 // that operands have already been simplified) "select(cond, B, C)" should
1556 // have been simplified to the common value of B and C already. Analysing
1557 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1558 // for threading over phi nodes.
1563 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1564 const TargetLibraryInfo *TLI,
1565 const DominatorTree *DT) {
1566 return ::SimplifyXorInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1569 static Type *GetCompareTy(Value *Op) {
1570 return CmpInst::makeCmpResultType(Op->getType());
1573 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1574 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1575 /// otherwise return null. Helper function for analyzing max/min idioms.
1576 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1577 Value *LHS, Value *RHS) {
1578 SelectInst *SI = dyn_cast<SelectInst>(V);
1581 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1584 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1585 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1587 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1588 LHS == CmpRHS && RHS == CmpLHS)
1594 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1595 /// fold the result. If not, this returns null.
1596 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1597 const Query &Q, unsigned MaxRecurse) {
1598 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1599 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1601 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1602 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1603 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI);
1605 // If we have a constant, make sure it is on the RHS.
1606 std::swap(LHS, RHS);
1607 Pred = CmpInst::getSwappedPredicate(Pred);
1610 Type *ITy = GetCompareTy(LHS); // The return type.
1611 Type *OpTy = LHS->getType(); // The operand type.
1613 // icmp X, X -> true/false
1614 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1615 // because X could be 0.
1616 if (LHS == RHS || isa<UndefValue>(RHS))
1617 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1619 // Special case logic when the operands have i1 type.
1620 if (OpTy->getScalarType()->isIntegerTy(1)) {
1623 case ICmpInst::ICMP_EQ:
1625 if (match(RHS, m_One()))
1628 case ICmpInst::ICMP_NE:
1630 if (match(RHS, m_Zero()))
1633 case ICmpInst::ICMP_UGT:
1635 if (match(RHS, m_Zero()))
1638 case ICmpInst::ICMP_UGE:
1640 if (match(RHS, m_One()))
1643 case ICmpInst::ICMP_SLT:
1645 if (match(RHS, m_Zero()))
1648 case ICmpInst::ICMP_SLE:
1650 if (match(RHS, m_One()))
1656 // icmp <object*>, <object*/null> - Different identified objects have
1657 // different addresses (unless null), and what's more the address of an
1658 // identified local is never equal to another argument (again, barring null).
1659 // Note that generalizing to the case where LHS is a global variable address
1660 // or null is pointless, since if both LHS and RHS are constants then we
1661 // already constant folded the compare, and if only one of them is then we
1662 // moved it to RHS already.
1663 Value *LHSPtr = LHS->stripPointerCasts();
1664 Value *RHSPtr = RHS->stripPointerCasts();
1665 if (LHSPtr == RHSPtr)
1666 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1668 // Be more aggressive about stripping pointer adjustments when checking a
1669 // comparison of an alloca address to another object. We can rip off all
1670 // inbounds GEP operations, even if they are variable.
1671 LHSPtr = LHSPtr->stripInBoundsOffsets();
1672 if (llvm::isIdentifiedObject(LHSPtr)) {
1673 RHSPtr = RHSPtr->stripInBoundsOffsets();
1674 if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) {
1675 // If both sides are different identified objects, they aren't equal
1676 // unless they're null.
1677 if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) &&
1678 Pred == CmpInst::ICMP_EQ)
1679 return ConstantInt::get(ITy, false);
1681 // A local identified object (alloca or noalias call) can't equal any
1682 // incoming argument, unless they're both null.
1683 if (isa<Instruction>(LHSPtr) && isa<Argument>(RHSPtr) &&
1684 Pred == CmpInst::ICMP_EQ)
1685 return ConstantInt::get(ITy, false);
1688 // Assume that the constant null is on the right.
1689 if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) {
1690 if (Pred == CmpInst::ICMP_EQ)
1691 return ConstantInt::get(ITy, false);
1692 else if (Pred == CmpInst::ICMP_NE)
1693 return ConstantInt::get(ITy, true);
1695 } else if (isa<Argument>(LHSPtr)) {
1696 RHSPtr = RHSPtr->stripInBoundsOffsets();
1697 // An alloca can't be equal to an argument.
1698 if (isa<AllocaInst>(RHSPtr)) {
1699 if (Pred == CmpInst::ICMP_EQ)
1700 return ConstantInt::get(ITy, false);
1701 else if (Pred == CmpInst::ICMP_NE)
1702 return ConstantInt::get(ITy, true);
1706 // If we are comparing with zero then try hard since this is a common case.
1707 if (match(RHS, m_Zero())) {
1708 bool LHSKnownNonNegative, LHSKnownNegative;
1710 default: llvm_unreachable("Unknown ICmp predicate!");
1711 case ICmpInst::ICMP_ULT:
1712 return getFalse(ITy);
1713 case ICmpInst::ICMP_UGE:
1714 return getTrue(ITy);
1715 case ICmpInst::ICMP_EQ:
1716 case ICmpInst::ICMP_ULE:
1717 if (isKnownNonZero(LHS, Q.TD))
1718 return getFalse(ITy);
1720 case ICmpInst::ICMP_NE:
1721 case ICmpInst::ICMP_UGT:
1722 if (isKnownNonZero(LHS, Q.TD))
1723 return getTrue(ITy);
1725 case ICmpInst::ICMP_SLT:
1726 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1727 if (LHSKnownNegative)
1728 return getTrue(ITy);
1729 if (LHSKnownNonNegative)
1730 return getFalse(ITy);
1732 case ICmpInst::ICMP_SLE:
1733 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1734 if (LHSKnownNegative)
1735 return getTrue(ITy);
1736 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
1737 return getFalse(ITy);
1739 case ICmpInst::ICMP_SGE:
1740 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1741 if (LHSKnownNegative)
1742 return getFalse(ITy);
1743 if (LHSKnownNonNegative)
1744 return getTrue(ITy);
1746 case ICmpInst::ICMP_SGT:
1747 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1748 if (LHSKnownNegative)
1749 return getFalse(ITy);
1750 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
1751 return getTrue(ITy);
1756 // See if we are doing a comparison with a constant integer.
1757 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1758 // Rule out tautological comparisons (eg., ult 0 or uge 0).
1759 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
1760 if (RHS_CR.isEmptySet())
1761 return ConstantInt::getFalse(CI->getContext());
1762 if (RHS_CR.isFullSet())
1763 return ConstantInt::getTrue(CI->getContext());
1765 // Many binary operators with constant RHS have easy to compute constant
1766 // range. Use them to check whether the comparison is a tautology.
1767 uint32_t Width = CI->getBitWidth();
1768 APInt Lower = APInt(Width, 0);
1769 APInt Upper = APInt(Width, 0);
1771 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
1772 // 'urem x, CI2' produces [0, CI2).
1773 Upper = CI2->getValue();
1774 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
1775 // 'srem x, CI2' produces (-|CI2|, |CI2|).
1776 Upper = CI2->getValue().abs();
1777 Lower = (-Upper) + 1;
1778 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
1779 // 'udiv CI2, x' produces [0, CI2].
1780 Upper = CI2->getValue() + 1;
1781 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
1782 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
1783 APInt NegOne = APInt::getAllOnesValue(Width);
1785 Upper = NegOne.udiv(CI2->getValue()) + 1;
1786 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
1787 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
1788 APInt IntMin = APInt::getSignedMinValue(Width);
1789 APInt IntMax = APInt::getSignedMaxValue(Width);
1790 APInt Val = CI2->getValue().abs();
1791 if (!Val.isMinValue()) {
1792 Lower = IntMin.sdiv(Val);
1793 Upper = IntMax.sdiv(Val) + 1;
1795 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
1796 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
1797 APInt NegOne = APInt::getAllOnesValue(Width);
1798 if (CI2->getValue().ult(Width))
1799 Upper = NegOne.lshr(CI2->getValue()) + 1;
1800 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
1801 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
1802 APInt IntMin = APInt::getSignedMinValue(Width);
1803 APInt IntMax = APInt::getSignedMaxValue(Width);
1804 if (CI2->getValue().ult(Width)) {
1805 Lower = IntMin.ashr(CI2->getValue());
1806 Upper = IntMax.ashr(CI2->getValue()) + 1;
1808 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
1809 // 'or x, CI2' produces [CI2, UINT_MAX].
1810 Lower = CI2->getValue();
1811 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
1812 // 'and x, CI2' produces [0, CI2].
1813 Upper = CI2->getValue() + 1;
1815 if (Lower != Upper) {
1816 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
1817 if (RHS_CR.contains(LHS_CR))
1818 return ConstantInt::getTrue(RHS->getContext());
1819 if (RHS_CR.inverse().contains(LHS_CR))
1820 return ConstantInt::getFalse(RHS->getContext());
1824 // Compare of cast, for example (zext X) != 0 -> X != 0
1825 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1826 Instruction *LI = cast<CastInst>(LHS);
1827 Value *SrcOp = LI->getOperand(0);
1828 Type *SrcTy = SrcOp->getType();
1829 Type *DstTy = LI->getType();
1831 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1832 // if the integer type is the same size as the pointer type.
1833 if (MaxRecurse && Q.TD && isa<PtrToIntInst>(LI) &&
1834 Q.TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1835 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1836 // Transfer the cast to the constant.
1837 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1838 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1841 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1842 if (RI->getOperand(0)->getType() == SrcTy)
1843 // Compare without the cast.
1844 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1850 if (isa<ZExtInst>(LHS)) {
1851 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1853 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1854 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1855 // Compare X and Y. Note that signed predicates become unsigned.
1856 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1857 SrcOp, RI->getOperand(0), Q,
1861 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1862 // too. If not, then try to deduce the result of the comparison.
1863 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1864 // Compute the constant that would happen if we truncated to SrcTy then
1865 // reextended to DstTy.
1866 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1867 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1869 // If the re-extended constant didn't change then this is effectively
1870 // also a case of comparing two zero-extended values.
1871 if (RExt == CI && MaxRecurse)
1872 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1873 SrcOp, Trunc, Q, MaxRecurse-1))
1876 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1877 // there. Use this to work out the result of the comparison.
1880 default: llvm_unreachable("Unknown ICmp predicate!");
1882 case ICmpInst::ICMP_EQ:
1883 case ICmpInst::ICMP_UGT:
1884 case ICmpInst::ICMP_UGE:
1885 return ConstantInt::getFalse(CI->getContext());
1887 case ICmpInst::ICMP_NE:
1888 case ICmpInst::ICMP_ULT:
1889 case ICmpInst::ICMP_ULE:
1890 return ConstantInt::getTrue(CI->getContext());
1892 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1893 // is non-negative then LHS <s RHS.
1894 case ICmpInst::ICMP_SGT:
1895 case ICmpInst::ICMP_SGE:
1896 return CI->getValue().isNegative() ?
1897 ConstantInt::getTrue(CI->getContext()) :
1898 ConstantInt::getFalse(CI->getContext());
1900 case ICmpInst::ICMP_SLT:
1901 case ICmpInst::ICMP_SLE:
1902 return CI->getValue().isNegative() ?
1903 ConstantInt::getFalse(CI->getContext()) :
1904 ConstantInt::getTrue(CI->getContext());
1910 if (isa<SExtInst>(LHS)) {
1911 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1913 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1914 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1915 // Compare X and Y. Note that the predicate does not change.
1916 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1920 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1921 // too. If not, then try to deduce the result of the comparison.
1922 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1923 // Compute the constant that would happen if we truncated to SrcTy then
1924 // reextended to DstTy.
1925 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1926 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1928 // If the re-extended constant didn't change then this is effectively
1929 // also a case of comparing two sign-extended values.
1930 if (RExt == CI && MaxRecurse)
1931 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
1934 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1935 // bits there. Use this to work out the result of the comparison.
1938 default: llvm_unreachable("Unknown ICmp predicate!");
1939 case ICmpInst::ICMP_EQ:
1940 return ConstantInt::getFalse(CI->getContext());
1941 case ICmpInst::ICMP_NE:
1942 return ConstantInt::getTrue(CI->getContext());
1944 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1946 case ICmpInst::ICMP_SGT:
1947 case ICmpInst::ICMP_SGE:
1948 return CI->getValue().isNegative() ?
1949 ConstantInt::getTrue(CI->getContext()) :
1950 ConstantInt::getFalse(CI->getContext());
1951 case ICmpInst::ICMP_SLT:
1952 case ICmpInst::ICMP_SLE:
1953 return CI->getValue().isNegative() ?
1954 ConstantInt::getFalse(CI->getContext()) :
1955 ConstantInt::getTrue(CI->getContext());
1957 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
1959 case ICmpInst::ICMP_UGT:
1960 case ICmpInst::ICMP_UGE:
1961 // Comparison is true iff the LHS <s 0.
1963 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
1964 Constant::getNullValue(SrcTy),
1968 case ICmpInst::ICMP_ULT:
1969 case ICmpInst::ICMP_ULE:
1970 // Comparison is true iff the LHS >=s 0.
1972 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
1973 Constant::getNullValue(SrcTy),
1983 // Special logic for binary operators.
1984 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
1985 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
1986 if (MaxRecurse && (LBO || RBO)) {
1987 // Analyze the case when either LHS or RHS is an add instruction.
1988 Value *A = 0, *B = 0, *C = 0, *D = 0;
1989 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
1990 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
1991 if (LBO && LBO->getOpcode() == Instruction::Add) {
1992 A = LBO->getOperand(0); B = LBO->getOperand(1);
1993 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
1994 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
1995 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
1997 if (RBO && RBO->getOpcode() == Instruction::Add) {
1998 C = RBO->getOperand(0); D = RBO->getOperand(1);
1999 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
2000 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2001 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2004 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2005 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2006 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2007 Constant::getNullValue(RHS->getType()),
2011 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2012 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2013 if (Value *V = SimplifyICmpInst(Pred,
2014 Constant::getNullValue(LHS->getType()),
2015 C == LHS ? D : C, Q, MaxRecurse-1))
2018 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2019 if (A && C && (A == C || A == D || B == C || B == D) &&
2020 NoLHSWrapProblem && NoRHSWrapProblem) {
2021 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2022 Value *Y = (A == C || A == D) ? B : A;
2023 Value *Z = (C == A || C == B) ? D : C;
2024 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
2029 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2030 bool KnownNonNegative, KnownNegative;
2034 case ICmpInst::ICMP_SGT:
2035 case ICmpInst::ICMP_SGE:
2036 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
2037 if (!KnownNonNegative)
2040 case ICmpInst::ICMP_EQ:
2041 case ICmpInst::ICMP_UGT:
2042 case ICmpInst::ICMP_UGE:
2043 return getFalse(ITy);
2044 case ICmpInst::ICMP_SLT:
2045 case ICmpInst::ICMP_SLE:
2046 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
2047 if (!KnownNonNegative)
2050 case ICmpInst::ICMP_NE:
2051 case ICmpInst::ICMP_ULT:
2052 case ICmpInst::ICMP_ULE:
2053 return getTrue(ITy);
2056 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2057 bool KnownNonNegative, KnownNegative;
2061 case ICmpInst::ICMP_SGT:
2062 case ICmpInst::ICMP_SGE:
2063 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
2064 if (!KnownNonNegative)
2067 case ICmpInst::ICMP_NE:
2068 case ICmpInst::ICMP_UGT:
2069 case ICmpInst::ICMP_UGE:
2070 return getTrue(ITy);
2071 case ICmpInst::ICMP_SLT:
2072 case ICmpInst::ICMP_SLE:
2073 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
2074 if (!KnownNonNegative)
2077 case ICmpInst::ICMP_EQ:
2078 case ICmpInst::ICMP_ULT:
2079 case ICmpInst::ICMP_ULE:
2080 return getFalse(ITy);
2085 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2086 // icmp pred (X /u Y), X
2087 if (Pred == ICmpInst::ICMP_UGT)
2088 return getFalse(ITy);
2089 if (Pred == ICmpInst::ICMP_ULE)
2090 return getTrue(ITy);
2093 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2094 LBO->getOperand(1) == RBO->getOperand(1)) {
2095 switch (LBO->getOpcode()) {
2097 case Instruction::UDiv:
2098 case Instruction::LShr:
2099 if (ICmpInst::isSigned(Pred))
2102 case Instruction::SDiv:
2103 case Instruction::AShr:
2104 if (!LBO->isExact() || !RBO->isExact())
2106 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2107 RBO->getOperand(0), Q, MaxRecurse-1))
2110 case Instruction::Shl: {
2111 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2112 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2115 if (!NSW && ICmpInst::isSigned(Pred))
2117 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2118 RBO->getOperand(0), Q, MaxRecurse-1))
2125 // Simplify comparisons involving max/min.
2127 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2128 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2130 // Signed variants on "max(a,b)>=a -> true".
2131 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2132 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2133 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2134 // We analyze this as smax(A, B) pred A.
2136 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2137 (A == LHS || B == LHS)) {
2138 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2139 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2140 // We analyze this as smax(A, B) swapped-pred A.
2141 P = CmpInst::getSwappedPredicate(Pred);
2142 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2143 (A == RHS || B == RHS)) {
2144 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2145 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2146 // We analyze this as smax(-A, -B) swapped-pred -A.
2147 // Note that we do not need to actually form -A or -B thanks to EqP.
2148 P = CmpInst::getSwappedPredicate(Pred);
2149 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2150 (A == LHS || B == LHS)) {
2151 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2152 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2153 // We analyze this as smax(-A, -B) pred -A.
2154 // Note that we do not need to actually form -A or -B thanks to EqP.
2157 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2158 // Cases correspond to "max(A, B) p A".
2162 case CmpInst::ICMP_EQ:
2163 case CmpInst::ICMP_SLE:
2164 // Equivalent to "A EqP B". This may be the same as the condition tested
2165 // in the max/min; if so, we can just return that.
2166 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2168 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2170 // Otherwise, see if "A EqP B" simplifies.
2172 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2175 case CmpInst::ICMP_NE:
2176 case CmpInst::ICMP_SGT: {
2177 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2178 // Equivalent to "A InvEqP B". This may be the same as the condition
2179 // tested in the max/min; if so, we can just return that.
2180 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2182 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2184 // Otherwise, see if "A InvEqP B" simplifies.
2186 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2190 case CmpInst::ICMP_SGE:
2192 return getTrue(ITy);
2193 case CmpInst::ICMP_SLT:
2195 return getFalse(ITy);
2199 // Unsigned variants on "max(a,b)>=a -> true".
2200 P = CmpInst::BAD_ICMP_PREDICATE;
2201 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2202 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2203 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2204 // We analyze this as umax(A, B) pred A.
2206 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2207 (A == LHS || B == LHS)) {
2208 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2209 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2210 // We analyze this as umax(A, B) swapped-pred A.
2211 P = CmpInst::getSwappedPredicate(Pred);
2212 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2213 (A == RHS || B == RHS)) {
2214 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2215 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2216 // We analyze this as umax(-A, -B) swapped-pred -A.
2217 // Note that we do not need to actually form -A or -B thanks to EqP.
2218 P = CmpInst::getSwappedPredicate(Pred);
2219 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2220 (A == LHS || B == LHS)) {
2221 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2222 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2223 // We analyze this as umax(-A, -B) pred -A.
2224 // Note that we do not need to actually form -A or -B thanks to EqP.
2227 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2228 // Cases correspond to "max(A, B) p A".
2232 case CmpInst::ICMP_EQ:
2233 case CmpInst::ICMP_ULE:
2234 // Equivalent to "A EqP B". This may be the same as the condition tested
2235 // in the max/min; if so, we can just return that.
2236 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2238 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2240 // Otherwise, see if "A EqP B" simplifies.
2242 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2245 case CmpInst::ICMP_NE:
2246 case CmpInst::ICMP_UGT: {
2247 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2248 // Equivalent to "A InvEqP B". This may be the same as the condition
2249 // tested in the max/min; if so, we can just return that.
2250 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2252 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2254 // Otherwise, see if "A InvEqP B" simplifies.
2256 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2260 case CmpInst::ICMP_UGE:
2262 return getTrue(ITy);
2263 case CmpInst::ICMP_ULT:
2265 return getFalse(ITy);
2269 // Variants on "max(x,y) >= min(x,z)".
2271 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2272 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2273 (A == C || A == D || B == C || B == D)) {
2274 // max(x, ?) pred min(x, ?).
2275 if (Pred == CmpInst::ICMP_SGE)
2277 return getTrue(ITy);
2278 if (Pred == CmpInst::ICMP_SLT)
2280 return getFalse(ITy);
2281 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2282 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2283 (A == C || A == D || B == C || B == D)) {
2284 // min(x, ?) pred max(x, ?).
2285 if (Pred == CmpInst::ICMP_SLE)
2287 return getTrue(ITy);
2288 if (Pred == CmpInst::ICMP_SGT)
2290 return getFalse(ITy);
2291 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2292 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2293 (A == C || A == D || B == C || B == D)) {
2294 // max(x, ?) pred min(x, ?).
2295 if (Pred == CmpInst::ICMP_UGE)
2297 return getTrue(ITy);
2298 if (Pred == CmpInst::ICMP_ULT)
2300 return getFalse(ITy);
2301 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2302 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2303 (A == C || A == D || B == C || B == D)) {
2304 // min(x, ?) pred max(x, ?).
2305 if (Pred == CmpInst::ICMP_ULE)
2307 return getTrue(ITy);
2308 if (Pred == CmpInst::ICMP_UGT)
2310 return getFalse(ITy);
2313 // Simplify comparisons of GEPs.
2314 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
2315 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
2316 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
2317 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
2318 (ICmpInst::isEquality(Pred) ||
2319 (GLHS->isInBounds() && GRHS->isInBounds() &&
2320 Pred == ICmpInst::getSignedPredicate(Pred)))) {
2321 // The bases are equal and the indices are constant. Build a constant
2322 // expression GEP with the same indices and a null base pointer to see
2323 // what constant folding can make out of it.
2324 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
2325 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
2326 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS);
2328 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
2329 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS);
2330 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
2335 // If the comparison is with the result of a select instruction, check whether
2336 // comparing with either branch of the select always yields the same value.
2337 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2338 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2341 // If the comparison is with the result of a phi instruction, check whether
2342 // doing the compare with each incoming phi value yields a common result.
2343 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2344 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2350 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2351 const TargetData *TD,
2352 const TargetLibraryInfo *TLI,
2353 const DominatorTree *DT) {
2354 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2358 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
2359 /// fold the result. If not, this returns null.
2360 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2361 const Query &Q, unsigned MaxRecurse) {
2362 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2363 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
2365 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2366 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2367 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI);
2369 // If we have a constant, make sure it is on the RHS.
2370 std::swap(LHS, RHS);
2371 Pred = CmpInst::getSwappedPredicate(Pred);
2374 // Fold trivial predicates.
2375 if (Pred == FCmpInst::FCMP_FALSE)
2376 return ConstantInt::get(GetCompareTy(LHS), 0);
2377 if (Pred == FCmpInst::FCMP_TRUE)
2378 return ConstantInt::get(GetCompareTy(LHS), 1);
2380 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
2381 return UndefValue::get(GetCompareTy(LHS));
2383 // fcmp x,x -> true/false. Not all compares are foldable.
2385 if (CmpInst::isTrueWhenEqual(Pred))
2386 return ConstantInt::get(GetCompareTy(LHS), 1);
2387 if (CmpInst::isFalseWhenEqual(Pred))
2388 return ConstantInt::get(GetCompareTy(LHS), 0);
2391 // Handle fcmp with constant RHS
2392 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2393 // If the constant is a nan, see if we can fold the comparison based on it.
2394 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2395 if (CFP->getValueAPF().isNaN()) {
2396 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
2397 return ConstantInt::getFalse(CFP->getContext());
2398 assert(FCmpInst::isUnordered(Pred) &&
2399 "Comparison must be either ordered or unordered!");
2400 // True if unordered.
2401 return ConstantInt::getTrue(CFP->getContext());
2403 // Check whether the constant is an infinity.
2404 if (CFP->getValueAPF().isInfinity()) {
2405 if (CFP->getValueAPF().isNegative()) {
2407 case FCmpInst::FCMP_OLT:
2408 // No value is ordered and less than negative infinity.
2409 return ConstantInt::getFalse(CFP->getContext());
2410 case FCmpInst::FCMP_UGE:
2411 // All values are unordered with or at least negative infinity.
2412 return ConstantInt::getTrue(CFP->getContext());
2418 case FCmpInst::FCMP_OGT:
2419 // No value is ordered and greater than infinity.
2420 return ConstantInt::getFalse(CFP->getContext());
2421 case FCmpInst::FCMP_ULE:
2422 // All values are unordered with and at most infinity.
2423 return ConstantInt::getTrue(CFP->getContext());
2432 // If the comparison is with the result of a select instruction, check whether
2433 // comparing with either branch of the select always yields the same value.
2434 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2435 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2438 // If the comparison is with the result of a phi instruction, check whether
2439 // doing the compare with each incoming phi value yields a common result.
2440 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2441 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2447 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2448 const TargetData *TD,
2449 const TargetLibraryInfo *TLI,
2450 const DominatorTree *DT) {
2451 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2455 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
2456 /// the result. If not, this returns null.
2457 static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
2458 Value *FalseVal, const Query &Q,
2459 unsigned MaxRecurse) {
2460 // select true, X, Y -> X
2461 // select false, X, Y -> Y
2462 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
2463 return CB->getZExtValue() ? TrueVal : FalseVal;
2465 // select C, X, X -> X
2466 if (TrueVal == FalseVal)
2469 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
2470 if (isa<Constant>(TrueVal))
2474 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
2476 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
2482 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
2483 const TargetData *TD,
2484 const TargetLibraryInfo *TLI,
2485 const DominatorTree *DT) {
2486 return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Query (TD, TLI, DT),
2490 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
2491 /// fold the result. If not, this returns null.
2492 static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) {
2493 // The type of the GEP pointer operand.
2494 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType());
2495 // The GEP pointer operand is not a pointer, it's a vector of pointers.
2499 // getelementptr P -> P.
2500 if (Ops.size() == 1)
2503 if (isa<UndefValue>(Ops[0])) {
2504 // Compute the (pointer) type returned by the GEP instruction.
2505 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
2506 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
2507 return UndefValue::get(GEPTy);
2510 if (Ops.size() == 2) {
2511 // getelementptr P, 0 -> P.
2512 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
2515 // getelementptr P, N -> P if P points to a type of zero size.
2517 Type *Ty = PtrTy->getElementType();
2518 if (Ty->isSized() && Q.TD->getTypeAllocSize(Ty) == 0)
2523 // Check to see if this is constant foldable.
2524 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2525 if (!isa<Constant>(Ops[i]))
2528 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
2531 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const TargetData *TD,
2532 const TargetLibraryInfo *TLI,
2533 const DominatorTree *DT) {
2534 return ::SimplifyGEPInst(Ops, Query (TD, TLI, DT), RecursionLimit);
2537 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
2538 /// can fold the result. If not, this returns null.
2539 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
2540 ArrayRef<unsigned> Idxs, const Query &Q,
2542 if (Constant *CAgg = dyn_cast<Constant>(Agg))
2543 if (Constant *CVal = dyn_cast<Constant>(Val))
2544 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
2546 // insertvalue x, undef, n -> x
2547 if (match(Val, m_Undef()))
2550 // insertvalue x, (extractvalue y, n), n
2551 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
2552 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
2553 EV->getIndices() == Idxs) {
2554 // insertvalue undef, (extractvalue y, n), n -> y
2555 if (match(Agg, m_Undef()))
2556 return EV->getAggregateOperand();
2558 // insertvalue y, (extractvalue y, n), n -> y
2559 if (Agg == EV->getAggregateOperand())
2566 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
2567 ArrayRef<unsigned> Idxs,
2568 const TargetData *TD,
2569 const TargetLibraryInfo *TLI,
2570 const DominatorTree *DT) {
2571 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query (TD, TLI, DT),
2575 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
2576 static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
2577 // If all of the PHI's incoming values are the same then replace the PHI node
2578 // with the common value.
2579 Value *CommonValue = 0;
2580 bool HasUndefInput = false;
2581 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
2582 Value *Incoming = PN->getIncomingValue(i);
2583 // If the incoming value is the phi node itself, it can safely be skipped.
2584 if (Incoming == PN) continue;
2585 if (isa<UndefValue>(Incoming)) {
2586 // Remember that we saw an undef value, but otherwise ignore them.
2587 HasUndefInput = true;
2590 if (CommonValue && Incoming != CommonValue)
2591 return 0; // Not the same, bail out.
2592 CommonValue = Incoming;
2595 // If CommonValue is null then all of the incoming values were either undef or
2596 // equal to the phi node itself.
2598 return UndefValue::get(PN->getType());
2600 // If we have a PHI node like phi(X, undef, X), where X is defined by some
2601 // instruction, we cannot return X as the result of the PHI node unless it
2602 // dominates the PHI block.
2604 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : 0;
2609 static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) {
2610 if (Constant *C = dyn_cast<Constant>(Op))
2611 return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.TD, Q.TLI);
2616 Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const TargetData *TD,
2617 const TargetLibraryInfo *TLI,
2618 const DominatorTree *DT) {
2619 return ::SimplifyTruncInst(Op, Ty, Query (TD, TLI, DT), RecursionLimit);
2622 //=== Helper functions for higher up the class hierarchy.
2624 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
2625 /// fold the result. If not, this returns null.
2626 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2627 const Query &Q, unsigned MaxRecurse) {
2629 case Instruction::Add:
2630 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2632 case Instruction::Sub:
2633 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2635 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
2636 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
2637 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
2638 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse);
2639 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
2640 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
2641 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse);
2642 case Instruction::Shl:
2643 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2645 case Instruction::LShr:
2646 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
2647 case Instruction::AShr:
2648 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
2649 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
2650 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
2651 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
2653 if (Constant *CLHS = dyn_cast<Constant>(LHS))
2654 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
2655 Constant *COps[] = {CLHS, CRHS};
2656 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.TD,
2660 // If the operation is associative, try some generic simplifications.
2661 if (Instruction::isAssociative(Opcode))
2662 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
2665 // If the operation is with the result of a select instruction check whether
2666 // operating on either branch of the select always yields the same value.
2667 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2668 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
2671 // If the operation is with the result of a phi instruction, check whether
2672 // operating on all incoming values of the phi always yields the same value.
2673 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2674 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
2681 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2682 const TargetData *TD, const TargetLibraryInfo *TLI,
2683 const DominatorTree *DT) {
2684 return ::SimplifyBinOp(Opcode, LHS, RHS, Query (TD, TLI, DT), RecursionLimit);
2687 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
2688 /// fold the result.
2689 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2690 const Query &Q, unsigned MaxRecurse) {
2691 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
2692 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
2693 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
2696 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2697 const TargetData *TD, const TargetLibraryInfo *TLI,
2698 const DominatorTree *DT) {
2699 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2703 static Value *SimplifyCallInst(CallInst *CI, const Query &) {
2704 // call undef -> undef
2705 if (isa<UndefValue>(CI->getCalledValue()))
2706 return UndefValue::get(CI->getType());
2711 /// SimplifyInstruction - See if we can compute a simplified version of this
2712 /// instruction. If not, this returns null.
2713 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
2714 const TargetLibraryInfo *TLI,
2715 const DominatorTree *DT) {
2718 switch (I->getOpcode()) {
2720 Result = ConstantFoldInstruction(I, TD, TLI);
2722 case Instruction::Add:
2723 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
2724 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2725 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2728 case Instruction::Sub:
2729 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
2730 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2731 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2734 case Instruction::Mul:
2735 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2737 case Instruction::SDiv:
2738 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2740 case Instruction::UDiv:
2741 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2743 case Instruction::FDiv:
2744 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2746 case Instruction::SRem:
2747 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2749 case Instruction::URem:
2750 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2752 case Instruction::FRem:
2753 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2755 case Instruction::Shl:
2756 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
2757 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2758 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2761 case Instruction::LShr:
2762 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
2763 cast<BinaryOperator>(I)->isExact(),
2766 case Instruction::AShr:
2767 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
2768 cast<BinaryOperator>(I)->isExact(),
2771 case Instruction::And:
2772 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2774 case Instruction::Or:
2775 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2777 case Instruction::Xor:
2778 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2780 case Instruction::ICmp:
2781 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
2782 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2784 case Instruction::FCmp:
2785 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
2786 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2788 case Instruction::Select:
2789 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
2790 I->getOperand(2), TD, TLI, DT);
2792 case Instruction::GetElementPtr: {
2793 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
2794 Result = SimplifyGEPInst(Ops, TD, TLI, DT);
2797 case Instruction::InsertValue: {
2798 InsertValueInst *IV = cast<InsertValueInst>(I);
2799 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
2800 IV->getInsertedValueOperand(),
2801 IV->getIndices(), TD, TLI, DT);
2804 case Instruction::PHI:
2805 Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT));
2807 case Instruction::Call:
2808 Result = SimplifyCallInst(cast<CallInst>(I), Query (TD, TLI, DT));
2810 case Instruction::Trunc:
2811 Result = SimplifyTruncInst(I->getOperand(0), I->getType(), TD, TLI, DT);
2815 /// If called on unreachable code, the above logic may report that the
2816 /// instruction simplified to itself. Make life easier for users by
2817 /// detecting that case here, returning a safe value instead.
2818 return Result == I ? UndefValue::get(I->getType()) : Result;
2821 /// \brief Implementation of recursive simplification through an instructions
2824 /// This is the common implementation of the recursive simplification routines.
2825 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
2826 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
2827 /// instructions to process and attempt to simplify it using
2828 /// InstructionSimplify.
2830 /// This routine returns 'true' only when *it* simplifies something. The passed
2831 /// in simplified value does not count toward this.
2832 static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
2833 const TargetData *TD,
2834 const TargetLibraryInfo *TLI,
2835 const DominatorTree *DT) {
2836 bool Simplified = false;
2837 SmallVector<Instruction *, 8> Worklist;
2839 // If we have an explicit value to collapse to, do that round of the
2840 // simplification loop by hand initially.
2842 for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
2844 Worklist.push_back(cast<Instruction>(*UI));
2846 // Replace the instruction with its simplified value.
2847 I->replaceAllUsesWith(SimpleV);
2849 // Gracefully handle edge cases where the instruction is not wired into any
2852 I->eraseFromParent();
2854 Worklist.push_back(I);
2857 while (!Worklist.empty()) {
2858 I = Worklist.pop_back_val();
2860 // See if this instruction simplifies.
2861 SimpleV = SimplifyInstruction(I, TD, TLI, DT);
2867 // Stash away all the uses of the old instruction so we can check them for
2868 // recursive simplifications after a RAUW. This is cheaper than checking all
2869 // uses of To on the recursive step in most cases.
2870 for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
2872 Worklist.push_back(cast<Instruction>(*UI));
2874 // Replace the instruction with its simplified value.
2875 I->replaceAllUsesWith(SimpleV);
2877 // Gracefully handle edge cases where the instruction is not wired into any
2880 I->eraseFromParent();
2885 bool llvm::recursivelySimplifyInstruction(Instruction *I,
2886 const TargetData *TD,
2887 const TargetLibraryInfo *TLI,
2888 const DominatorTree *DT) {
2889 return replaceAndRecursivelySimplifyImpl(I, 0, TD, TLI, DT);
2892 bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
2893 const TargetData *TD,
2894 const TargetLibraryInfo *TLI,
2895 const DominatorTree *DT) {
2896 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
2897 assert(SimpleV && "Must provide a simplified value.");
2898 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TD, TLI, DT);