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/ADT/SetVector.h"
25 #include "llvm/Analysis/InstructionSimplify.h"
26 #include "llvm/Analysis/AliasAnalysis.h"
27 #include "llvm/Analysis/ConstantFolding.h"
28 #include "llvm/Analysis/Dominators.h"
29 #include "llvm/Analysis/ValueTracking.h"
30 #include "llvm/Support/ConstantRange.h"
31 #include "llvm/Support/GetElementPtrTypeIterator.h"
32 #include "llvm/Support/PatternMatch.h"
33 #include "llvm/Support/ValueHandle.h"
34 #include "llvm/DataLayout.h"
36 using namespace llvm::PatternMatch;
38 enum { RecursionLimit = 3 };
40 STATISTIC(NumExpand, "Number of expansions");
41 STATISTIC(NumFactor , "Number of factorizations");
42 STATISTIC(NumReassoc, "Number of reassociations");
46 const TargetLibraryInfo *TLI;
47 const DominatorTree *DT;
49 Query(const DataLayout *td, const TargetLibraryInfo *tli,
50 const DominatorTree *dt) : TD(td), TLI(tli), DT(dt) {}
53 static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
54 static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
56 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
58 static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
59 static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
60 static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned);
62 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
63 /// a vector with every element false, as appropriate for the type.
64 static Constant *getFalse(Type *Ty) {
65 assert(Ty->getScalarType()->isIntegerTy(1) &&
66 "Expected i1 type or a vector of i1!");
67 return Constant::getNullValue(Ty);
70 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
71 /// a vector with every element true, as appropriate for the type.
72 static Constant *getTrue(Type *Ty) {
73 assert(Ty->getScalarType()->isIntegerTy(1) &&
74 "Expected i1 type or a vector of i1!");
75 return Constant::getAllOnesValue(Ty);
78 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
79 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
81 CmpInst *Cmp = dyn_cast<CmpInst>(V);
84 CmpInst::Predicate CPred = Cmp->getPredicate();
85 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
86 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
88 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
92 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
93 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
94 Instruction *I = dyn_cast<Instruction>(V);
96 // Arguments and constants dominate all instructions.
99 // If we are processing instructions (and/or basic blocks) that have not been
100 // fully added to a function, the parent nodes may still be null. Simply
101 // return the conservative answer in these cases.
102 if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
105 // If we have a DominatorTree then do a precise test.
107 if (!DT->isReachableFromEntry(P->getParent()))
109 if (!DT->isReachableFromEntry(I->getParent()))
111 return DT->dominates(I, P);
114 // Otherwise, if the instruction is in the entry block, and is not an invoke,
115 // then it obviously dominates all phi nodes.
116 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
123 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
124 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
125 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
126 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
127 /// Returns the simplified value, or null if no simplification was performed.
128 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
129 unsigned OpcToExpand, const Query &Q,
130 unsigned MaxRecurse) {
131 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
132 // Recursion is always used, so bail out at once if we already hit the limit.
136 // Check whether the expression has the form "(A op' B) op C".
137 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
138 if (Op0->getOpcode() == OpcodeToExpand) {
139 // It does! Try turning it into "(A op C) op' (B op C)".
140 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
141 // Do "A op C" and "B op C" both simplify?
142 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
143 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
144 // They do! Return "L op' R" if it simplifies or is already available.
145 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
146 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
147 && L == B && R == A)) {
151 // Otherwise return "L op' R" if it simplifies.
152 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
159 // Check whether the expression has the form "A op (B op' C)".
160 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
161 if (Op1->getOpcode() == OpcodeToExpand) {
162 // It does! Try turning it into "(A op B) op' (A op C)".
163 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
164 // Do "A op B" and "A op C" both simplify?
165 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
166 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
167 // They do! Return "L op' R" if it simplifies or is already available.
168 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
169 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
170 && L == C && R == B)) {
174 // Otherwise return "L op' R" if it simplifies.
175 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
185 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
186 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
187 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
188 /// Returns the simplified value, or null if no simplification was performed.
189 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
190 unsigned OpcToExtract, const Query &Q,
191 unsigned MaxRecurse) {
192 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
193 // Recursion is always used, so bail out at once if we already hit the limit.
197 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
198 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
200 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
201 !Op1 || Op1->getOpcode() != OpcodeToExtract)
204 // The expression has the form "(A op' B) op (C op' D)".
205 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
206 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
208 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
209 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
210 // commutative case, "(A op' B) op (C op' A)"?
211 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
212 Value *DD = A == C ? D : C;
213 // Form "A op' (B op DD)" if it simplifies completely.
214 // Does "B op DD" simplify?
215 if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) {
216 // It does! Return "A op' V" if it simplifies or is already available.
217 // If V equals B then "A op' V" is just the LHS. If V equals DD then
218 // "A op' V" is just the RHS.
219 if (V == B || V == DD) {
221 return V == B ? LHS : RHS;
223 // Otherwise return "A op' V" if it simplifies.
224 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) {
231 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
232 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
233 // commutative case, "(A op' B) op (B op' D)"?
234 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
235 Value *CC = B == D ? C : D;
236 // Form "(A op CC) op' B" if it simplifies completely..
237 // Does "A op CC" simplify?
238 if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) {
239 // It does! Return "V op' B" if it simplifies or is already available.
240 // If V equals A then "V op' B" is just the LHS. If V equals CC then
241 // "V op' B" is just the RHS.
242 if (V == A || V == CC) {
244 return V == A ? LHS : RHS;
246 // Otherwise return "V op' B" if it simplifies.
247 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) {
257 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
258 /// operations. Returns the simpler value, or null if none was found.
259 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
260 const Query &Q, unsigned MaxRecurse) {
261 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
262 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
264 // Recursion is always used, so bail out at once if we already hit the limit.
268 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
269 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
271 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
272 if (Op0 && Op0->getOpcode() == Opcode) {
273 Value *A = Op0->getOperand(0);
274 Value *B = Op0->getOperand(1);
277 // Does "B op C" simplify?
278 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
279 // It does! Return "A op V" if it simplifies or is already available.
280 // If V equals B then "A op V" is just the LHS.
281 if (V == B) return LHS;
282 // Otherwise return "A op V" if it simplifies.
283 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
290 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
291 if (Op1 && Op1->getOpcode() == Opcode) {
293 Value *B = Op1->getOperand(0);
294 Value *C = Op1->getOperand(1);
296 // Does "A op B" simplify?
297 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
298 // It does! Return "V op C" if it simplifies or is already available.
299 // If V equals B then "V op C" is just the RHS.
300 if (V == B) return RHS;
301 // Otherwise return "V op C" if it simplifies.
302 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
309 // The remaining transforms require commutativity as well as associativity.
310 if (!Instruction::isCommutative(Opcode))
313 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
314 if (Op0 && Op0->getOpcode() == Opcode) {
315 Value *A = Op0->getOperand(0);
316 Value *B = Op0->getOperand(1);
319 // Does "C op A" simplify?
320 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
321 // It does! Return "V op B" if it simplifies or is already available.
322 // If V equals A then "V op B" is just the LHS.
323 if (V == A) return LHS;
324 // Otherwise return "V op B" if it simplifies.
325 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
332 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
333 if (Op1 && Op1->getOpcode() == Opcode) {
335 Value *B = Op1->getOperand(0);
336 Value *C = Op1->getOperand(1);
338 // Does "C op A" simplify?
339 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
340 // It does! Return "B op V" if it simplifies or is already available.
341 // If V equals C then "B op V" is just the RHS.
342 if (V == C) return RHS;
343 // Otherwise return "B op V" if it simplifies.
344 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
354 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
355 /// instruction as an operand, try to simplify the binop by seeing whether
356 /// evaluating it on both branches of the select results in the same value.
357 /// Returns the common value if so, otherwise returns null.
358 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
359 const Query &Q, unsigned MaxRecurse) {
360 // Recursion is always used, so bail out at once if we already hit the limit.
365 if (isa<SelectInst>(LHS)) {
366 SI = cast<SelectInst>(LHS);
368 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
369 SI = cast<SelectInst>(RHS);
372 // Evaluate the BinOp on the true and false branches of the select.
376 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
377 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
379 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
380 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
383 // If they simplified to the same value, then return the common value.
384 // If they both failed to simplify then return null.
388 // If one branch simplified to undef, return the other one.
389 if (TV && isa<UndefValue>(TV))
391 if (FV && isa<UndefValue>(FV))
394 // If applying the operation did not change the true and false select values,
395 // then the result of the binop is the select itself.
396 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
399 // If one branch simplified and the other did not, and the simplified
400 // value is equal to the unsimplified one, return the simplified value.
401 // For example, select (cond, X, X & Z) & Z -> X & Z.
402 if ((FV && !TV) || (TV && !FV)) {
403 // Check that the simplified value has the form "X op Y" where "op" is the
404 // same as the original operation.
405 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
406 if (Simplified && Simplified->getOpcode() == Opcode) {
407 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
408 // We already know that "op" is the same as for the simplified value. See
409 // if the operands match too. If so, return the simplified value.
410 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
411 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
412 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
413 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
414 Simplified->getOperand(1) == UnsimplifiedRHS)
416 if (Simplified->isCommutative() &&
417 Simplified->getOperand(1) == UnsimplifiedLHS &&
418 Simplified->getOperand(0) == UnsimplifiedRHS)
426 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
427 /// try to simplify the comparison by seeing whether both branches of the select
428 /// result in the same value. Returns the common value if so, otherwise returns
430 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
431 Value *RHS, const Query &Q,
432 unsigned MaxRecurse) {
433 // Recursion is always used, so bail out at once if we already hit the limit.
437 // Make sure the select is on the LHS.
438 if (!isa<SelectInst>(LHS)) {
440 Pred = CmpInst::getSwappedPredicate(Pred);
442 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
443 SelectInst *SI = cast<SelectInst>(LHS);
444 Value *Cond = SI->getCondition();
445 Value *TV = SI->getTrueValue();
446 Value *FV = SI->getFalseValue();
448 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
449 // Does "cmp TV, RHS" simplify?
450 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
452 // It not only simplified, it simplified to the select condition. Replace
454 TCmp = getTrue(Cond->getType());
456 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
457 // condition then we can replace it with 'true'. Otherwise give up.
458 if (!isSameCompare(Cond, Pred, TV, RHS))
460 TCmp = getTrue(Cond->getType());
463 // Does "cmp FV, RHS" simplify?
464 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
466 // It not only simplified, it simplified to the select condition. Replace
468 FCmp = getFalse(Cond->getType());
470 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
471 // condition then we can replace it with 'false'. Otherwise give up.
472 if (!isSameCompare(Cond, Pred, FV, RHS))
474 FCmp = getFalse(Cond->getType());
477 // If both sides simplified to the same value, then use it as the result of
478 // the original comparison.
482 // The remaining cases only make sense if the select condition has the same
483 // type as the result of the comparison, so bail out if this is not so.
484 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
486 // If the false value simplified to false, then the result of the compare
487 // is equal to "Cond && TCmp". This also catches the case when the false
488 // value simplified to false and the true value to true, returning "Cond".
489 if (match(FCmp, m_Zero()))
490 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
492 // If the true value simplified to true, then the result of the compare
493 // is equal to "Cond || FCmp".
494 if (match(TCmp, m_One()))
495 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
497 // Finally, if the false value simplified to true and the true value to
498 // false, then the result of the compare is equal to "!Cond".
499 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
501 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
508 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
509 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
510 /// it on the incoming phi values yields the same result for every value. If so
511 /// returns the common value, otherwise returns null.
512 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
513 const Query &Q, unsigned MaxRecurse) {
514 // Recursion is always used, so bail out at once if we already hit the limit.
519 if (isa<PHINode>(LHS)) {
520 PI = cast<PHINode>(LHS);
521 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
522 if (!ValueDominatesPHI(RHS, PI, Q.DT))
525 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
526 PI = cast<PHINode>(RHS);
527 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
528 if (!ValueDominatesPHI(LHS, PI, Q.DT))
532 // Evaluate the BinOp on the incoming phi values.
533 Value *CommonValue = 0;
534 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
535 Value *Incoming = PI->getIncomingValue(i);
536 // If the incoming value is the phi node itself, it can safely be skipped.
537 if (Incoming == PI) continue;
538 Value *V = PI == LHS ?
539 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
540 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
541 // If the operation failed to simplify, or simplified to a different value
542 // to previously, then give up.
543 if (!V || (CommonValue && V != CommonValue))
551 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
552 /// try to simplify the comparison by seeing whether comparing with all of the
553 /// incoming phi values yields the same result every time. If so returns the
554 /// common result, otherwise returns null.
555 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
556 const Query &Q, unsigned MaxRecurse) {
557 // Recursion is always used, so bail out at once if we already hit the limit.
561 // Make sure the phi is on the LHS.
562 if (!isa<PHINode>(LHS)) {
564 Pred = CmpInst::getSwappedPredicate(Pred);
566 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
567 PHINode *PI = cast<PHINode>(LHS);
569 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
570 if (!ValueDominatesPHI(RHS, PI, Q.DT))
573 // Evaluate the BinOp on the incoming phi values.
574 Value *CommonValue = 0;
575 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
576 Value *Incoming = PI->getIncomingValue(i);
577 // If the incoming value is the phi node itself, it can safely be skipped.
578 if (Incoming == PI) continue;
579 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
580 // If the operation failed to simplify, or simplified to a different value
581 // to previously, then give up.
582 if (!V || (CommonValue && V != CommonValue))
590 /// SimplifyAddInst - Given operands for an Add, see if we can
591 /// fold the result. If not, this returns null.
592 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
593 const Query &Q, unsigned MaxRecurse) {
594 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
595 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
596 Constant *Ops[] = { CLHS, CRHS };
597 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops,
601 // Canonicalize the constant to the RHS.
605 // X + undef -> undef
606 if (match(Op1, m_Undef()))
610 if (match(Op1, m_Zero()))
617 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
618 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
621 // X + ~X -> -1 since ~X = -X-1
622 if (match(Op0, m_Not(m_Specific(Op1))) ||
623 match(Op1, m_Not(m_Specific(Op0))))
624 return Constant::getAllOnesValue(Op0->getType());
627 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
628 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
631 // Try some generic simplifications for associative operations.
632 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
636 // Mul distributes over Add. Try some generic simplifications based on this.
637 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
641 // Threading Add over selects and phi nodes is pointless, so don't bother.
642 // Threading over the select in "A + select(cond, B, C)" means evaluating
643 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
644 // only if B and C are equal. If B and C are equal then (since we assume
645 // that operands have already been simplified) "select(cond, B, C)" should
646 // have been simplified to the common value of B and C already. Analysing
647 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
648 // for threading over phi nodes.
653 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
654 const DataLayout *TD, const TargetLibraryInfo *TLI,
655 const DominatorTree *DT) {
656 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
660 /// \brief Accumulate the constant integer offset a GEP represents.
662 /// Given a getelementptr instruction/constantexpr, accumulate the constant
663 /// offset from the base pointer into the provided APInt 'Offset'. Returns true
664 /// if the GEP has all-constant indices. Returns false if any non-constant
665 /// index is encountered leaving the 'Offset' in an undefined state. The
666 /// 'Offset' APInt must be the bitwidth of the target's pointer size.
667 static bool accumulateGEPOffset(const DataLayout &TD, GEPOperator *GEP,
669 unsigned AS = GEP->getPointerAddressSpace();
670 unsigned IntPtrWidth = TD.getPointerSizeInBits(AS);
671 assert(IntPtrWidth == Offset.getBitWidth());
673 gep_type_iterator GTI = gep_type_begin(GEP);
674 for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end(); I != E;
676 ConstantInt *OpC = dyn_cast<ConstantInt>(*I);
677 if (!OpC) return false;
678 if (OpC->isZero()) continue;
680 // Handle a struct index, which adds its field offset to the pointer.
681 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
682 unsigned ElementIdx = OpC->getZExtValue();
683 const StructLayout *SL = TD.getStructLayout(STy);
684 Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
688 APInt TypeSize(IntPtrWidth, TD.getTypeAllocSize(GTI.getIndexedType()));
689 Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
694 /// \brief Compute the base pointer and cumulative constant offsets for V.
696 /// This strips all constant offsets off of V, leaving it the base pointer, and
697 /// accumulates the total constant offset applied in the returned constant. It
698 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
699 /// no constant offsets applied.
700 /// FIXME: This function also exists in InlineCost.cpp.
701 static Constant *stripAndComputeConstantOffsets(const DataLayout &TD,
703 if (!V->getType()->isPointerTy())
706 unsigned AS = cast<PointerType>(V->getType())->getAddressSpace();;
707 unsigned IntPtrWidth = TD.getPointerSizeInBits(AS);
708 APInt Offset = APInt::getNullValue(IntPtrWidth);
710 // Even though we don't look through PHI nodes, we could be called on an
711 // instruction in an unreachable block, which may be on a cycle.
712 SmallPtrSet<Value *, 4> Visited;
715 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
716 if (!GEP->isInBounds() || !accumulateGEPOffset(TD, GEP, Offset))
718 V = GEP->getPointerOperand();
719 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
720 V = cast<Operator>(V)->getOperand(0);
721 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
722 if (GA->mayBeOverridden())
724 V = GA->getAliasee();
728 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
729 } while (Visited.insert(V));
731 Type *IntPtrTy = TD.getIntPtrType(V->getContext());
732 return ConstantInt::get(IntPtrTy, Offset);
735 /// \brief Compute the constant difference between two pointer values.
736 /// If the difference is not a constant, returns zero.
737 static Constant *computePointerDifference(const DataLayout &TD,
738 Value *LHS, Value *RHS) {
739 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
742 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
746 // If LHS and RHS are not related via constant offsets to the same base
747 // value, there is nothing we can do here.
751 // Otherwise, the difference of LHS - RHS can be computed as:
753 // = (LHSOffset + Base) - (RHSOffset + Base)
754 // = LHSOffset - RHSOffset
755 return ConstantExpr::getSub(LHSOffset, RHSOffset);
758 /// SimplifySubInst - Given operands for a Sub, see if we can
759 /// fold the result. If not, this returns null.
760 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
761 const Query &Q, unsigned MaxRecurse) {
762 if (Constant *CLHS = dyn_cast<Constant>(Op0))
763 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
764 Constant *Ops[] = { CLHS, CRHS };
765 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
769 // X - undef -> undef
770 // undef - X -> undef
771 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
772 return UndefValue::get(Op0->getType());
775 if (match(Op1, m_Zero()))
780 return Constant::getNullValue(Op0->getType());
785 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
786 match(Op0, m_Shl(m_Specific(Op1), m_One())))
789 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
790 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
791 Value *Y = 0, *Z = Op1;
792 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
793 // See if "V === Y - Z" simplifies.
794 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
795 // It does! Now see if "X + V" simplifies.
796 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
797 // It does, we successfully reassociated!
801 // See if "V === X - Z" simplifies.
802 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
803 // It does! Now see if "Y + V" simplifies.
804 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
805 // It does, we successfully reassociated!
811 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
812 // For example, X - (X + 1) -> -1
814 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
815 // See if "V === X - Y" simplifies.
816 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
817 // It does! Now see if "V - Z" simplifies.
818 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
819 // It does, we successfully reassociated!
823 // See if "V === X - Z" simplifies.
824 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
825 // It does! Now see if "V - Y" simplifies.
826 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
827 // It does, we successfully reassociated!
833 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
834 // For example, X - (X - Y) -> Y.
836 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
837 // See if "V === Z - X" simplifies.
838 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
839 // It does! Now see if "V + Y" simplifies.
840 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
841 // It does, we successfully reassociated!
846 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
847 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
848 match(Op1, m_Trunc(m_Value(Y))))
849 if (X->getType() == Y->getType())
850 // See if "V === X - Y" simplifies.
851 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
852 // It does! Now see if "trunc V" simplifies.
853 if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1))
854 // It does, return the simplified "trunc V".
857 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
858 if (Q.TD && match(Op0, m_PtrToInt(m_Value(X))) &&
859 match(Op1, m_PtrToInt(m_Value(Y))))
860 if (Constant *Result = computePointerDifference(*Q.TD, X, Y))
861 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
863 // Mul distributes over Sub. Try some generic simplifications based on this.
864 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
869 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
870 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
873 // Threading Sub over selects and phi nodes is pointless, so don't bother.
874 // Threading over the select in "A - select(cond, B, C)" means evaluating
875 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
876 // only if B and C are equal. If B and C are equal then (since we assume
877 // that operands have already been simplified) "select(cond, B, C)" should
878 // have been simplified to the common value of B and C already. Analysing
879 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
880 // for threading over phi nodes.
885 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
886 const DataLayout *TD, const TargetLibraryInfo *TLI,
887 const DominatorTree *DT) {
888 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
892 /// SimplifyMulInst - Given operands for a Mul, see if we can
893 /// fold the result. If not, this returns null.
894 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
895 unsigned MaxRecurse) {
896 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
897 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
898 Constant *Ops[] = { CLHS, CRHS };
899 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
903 // Canonicalize the constant to the RHS.
908 if (match(Op1, m_Undef()))
909 return Constant::getNullValue(Op0->getType());
912 if (match(Op1, m_Zero()))
916 if (match(Op1, m_One()))
919 // (X / Y) * Y -> X if the division is exact.
921 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
922 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
926 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
927 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
930 // Try some generic simplifications for associative operations.
931 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
935 // Mul distributes over Add. Try some generic simplifications based on this.
936 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
940 // If the operation is with the result of a select instruction, check whether
941 // operating on either branch of the select always yields the same value.
942 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
943 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
947 // If the operation is with the result of a phi instruction, check whether
948 // operating on all incoming values of the phi always yields the same value.
949 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
950 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
957 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const DataLayout *TD,
958 const TargetLibraryInfo *TLI,
959 const DominatorTree *DT) {
960 return ::SimplifyMulInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
963 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
964 /// fold the result. If not, this returns null.
965 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
966 const Query &Q, unsigned MaxRecurse) {
967 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
968 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
969 Constant *Ops[] = { C0, C1 };
970 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
974 bool isSigned = Opcode == Instruction::SDiv;
976 // X / undef -> undef
977 if (match(Op1, m_Undef()))
981 if (match(Op0, m_Undef()))
982 return Constant::getNullValue(Op0->getType());
984 // 0 / X -> 0, we don't need to preserve faults!
985 if (match(Op0, m_Zero()))
989 if (match(Op1, m_One()))
992 if (Op0->getType()->isIntegerTy(1))
993 // It can't be division by zero, hence it must be division by one.
998 return ConstantInt::get(Op0->getType(), 1);
1000 // (X * Y) / Y -> X if the multiplication does not overflow.
1001 Value *X = 0, *Y = 0;
1002 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
1003 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
1004 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
1005 // If the Mul knows it does not overflow, then we are good to go.
1006 if ((isSigned && Mul->hasNoSignedWrap()) ||
1007 (!isSigned && Mul->hasNoUnsignedWrap()))
1009 // If X has the form X = A / Y then X * Y cannot overflow.
1010 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
1011 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1015 // (X rem Y) / Y -> 0
1016 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1017 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1018 return Constant::getNullValue(Op0->getType());
1020 // If the operation is with the result of a select instruction, check whether
1021 // operating on either branch of the select always yields the same value.
1022 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1023 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1026 // If the operation is with the result of a phi instruction, check whether
1027 // operating on all incoming values of the phi always yields the same value.
1028 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1029 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1035 /// SimplifySDivInst - Given operands for an SDiv, see if we can
1036 /// fold the result. If not, this returns null.
1037 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
1038 unsigned MaxRecurse) {
1039 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
1045 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const DataLayout *TD,
1046 const TargetLibraryInfo *TLI,
1047 const DominatorTree *DT) {
1048 return ::SimplifySDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1051 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
1052 /// fold the result. If not, this returns null.
1053 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
1054 unsigned MaxRecurse) {
1055 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
1061 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const DataLayout *TD,
1062 const TargetLibraryInfo *TLI,
1063 const DominatorTree *DT) {
1064 return ::SimplifyUDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1067 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q,
1069 // undef / X -> undef (the undef could be a snan).
1070 if (match(Op0, m_Undef()))
1073 // X / undef -> undef
1074 if (match(Op1, m_Undef()))
1080 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const DataLayout *TD,
1081 const TargetLibraryInfo *TLI,
1082 const DominatorTree *DT) {
1083 return ::SimplifyFDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1086 /// SimplifyRem - Given operands for an SRem or URem, see if we can
1087 /// fold the result. If not, this returns null.
1088 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1089 const Query &Q, unsigned MaxRecurse) {
1090 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1091 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1092 Constant *Ops[] = { C0, C1 };
1093 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
1097 // X % undef -> undef
1098 if (match(Op1, m_Undef()))
1102 if (match(Op0, m_Undef()))
1103 return Constant::getNullValue(Op0->getType());
1105 // 0 % X -> 0, we don't need to preserve faults!
1106 if (match(Op0, m_Zero()))
1109 // X % 0 -> undef, we don't need to preserve faults!
1110 if (match(Op1, m_Zero()))
1111 return UndefValue::get(Op0->getType());
1114 if (match(Op1, m_One()))
1115 return Constant::getNullValue(Op0->getType());
1117 if (Op0->getType()->isIntegerTy(1))
1118 // It can't be remainder by zero, hence it must be remainder by one.
1119 return Constant::getNullValue(Op0->getType());
1123 return Constant::getNullValue(Op0->getType());
1125 // If the operation is with the result of a select instruction, check whether
1126 // operating on either branch of the select always yields the same value.
1127 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1128 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1131 // If the operation is with the result of a phi instruction, check whether
1132 // operating on all incoming values of the phi always yields the same value.
1133 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1134 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1140 /// SimplifySRemInst - Given operands for an SRem, see if we can
1141 /// fold the result. If not, this returns null.
1142 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
1143 unsigned MaxRecurse) {
1144 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
1150 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const DataLayout *TD,
1151 const TargetLibraryInfo *TLI,
1152 const DominatorTree *DT) {
1153 return ::SimplifySRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1156 /// SimplifyURemInst - Given operands for a URem, see if we can
1157 /// fold the result. If not, this returns null.
1158 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
1159 unsigned MaxRecurse) {
1160 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
1166 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const DataLayout *TD,
1167 const TargetLibraryInfo *TLI,
1168 const DominatorTree *DT) {
1169 return ::SimplifyURemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1172 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &,
1174 // undef % X -> undef (the undef could be a snan).
1175 if (match(Op0, m_Undef()))
1178 // X % undef -> undef
1179 if (match(Op1, m_Undef()))
1185 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const DataLayout *TD,
1186 const TargetLibraryInfo *TLI,
1187 const DominatorTree *DT) {
1188 return ::SimplifyFRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1191 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1192 /// fold the result. If not, this returns null.
1193 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1194 const Query &Q, unsigned MaxRecurse) {
1195 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1196 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1197 Constant *Ops[] = { C0, C1 };
1198 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
1202 // 0 shift by X -> 0
1203 if (match(Op0, m_Zero()))
1206 // X shift by 0 -> X
1207 if (match(Op1, m_Zero()))
1210 // X shift by undef -> undef because it may shift by the bitwidth.
1211 if (match(Op1, m_Undef()))
1214 // Shifting by the bitwidth or more is undefined.
1215 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
1216 if (CI->getValue().getLimitedValue() >=
1217 Op0->getType()->getScalarSizeInBits())
1218 return UndefValue::get(Op0->getType());
1220 // If the operation is with the result of a select instruction, check whether
1221 // operating on either branch of the select always yields the same value.
1222 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1223 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1226 // If the operation is with the result of a phi instruction, check whether
1227 // operating on all incoming values of the phi always yields the same value.
1228 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1229 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1235 /// SimplifyShlInst - Given operands for an Shl, see if we can
1236 /// fold the result. If not, this returns null.
1237 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1238 const Query &Q, unsigned MaxRecurse) {
1239 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1243 if (match(Op0, m_Undef()))
1244 return Constant::getNullValue(Op0->getType());
1246 // (X >> A) << A -> X
1248 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1253 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1254 const DataLayout *TD, const TargetLibraryInfo *TLI,
1255 const DominatorTree *DT) {
1256 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
1260 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1261 /// fold the result. If not, this returns null.
1262 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1263 const Query &Q, unsigned MaxRecurse) {
1264 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse))
1268 if (match(Op0, m_Undef()))
1269 return Constant::getNullValue(Op0->getType());
1271 // (X << A) >> A -> X
1273 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1274 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
1280 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1281 const DataLayout *TD,
1282 const TargetLibraryInfo *TLI,
1283 const DominatorTree *DT) {
1284 return ::SimplifyLShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
1288 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1289 /// fold the result. If not, this returns null.
1290 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1291 const Query &Q, unsigned MaxRecurse) {
1292 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse))
1295 // all ones >>a X -> all ones
1296 if (match(Op0, m_AllOnes()))
1299 // undef >>a X -> all ones
1300 if (match(Op0, m_Undef()))
1301 return Constant::getAllOnesValue(Op0->getType());
1303 // (X << A) >> A -> X
1305 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1306 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
1312 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1313 const DataLayout *TD,
1314 const TargetLibraryInfo *TLI,
1315 const DominatorTree *DT) {
1316 return ::SimplifyAShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
1320 /// SimplifyAndInst - Given operands for an And, see if we can
1321 /// fold the result. If not, this returns null.
1322 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
1323 unsigned MaxRecurse) {
1324 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1325 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1326 Constant *Ops[] = { CLHS, CRHS };
1327 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1331 // Canonicalize the constant to the RHS.
1332 std::swap(Op0, Op1);
1336 if (match(Op1, m_Undef()))
1337 return Constant::getNullValue(Op0->getType());
1344 if (match(Op1, m_Zero()))
1348 if (match(Op1, m_AllOnes()))
1351 // A & ~A = ~A & A = 0
1352 if (match(Op0, m_Not(m_Specific(Op1))) ||
1353 match(Op1, m_Not(m_Specific(Op0))))
1354 return Constant::getNullValue(Op0->getType());
1357 Value *A = 0, *B = 0;
1358 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1359 (A == Op1 || B == Op1))
1363 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1364 (A == Op0 || B == Op0))
1367 // A & (-A) = A if A is a power of two or zero.
1368 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1369 match(Op1, m_Neg(m_Specific(Op0)))) {
1370 if (isPowerOfTwo(Op0, Q.TD, /*OrZero*/true))
1372 if (isPowerOfTwo(Op1, Q.TD, /*OrZero*/true))
1376 // Try some generic simplifications for associative operations.
1377 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1381 // And distributes over Or. Try some generic simplifications based on this.
1382 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1386 // And distributes over Xor. Try some generic simplifications based on this.
1387 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1391 // Or distributes over And. Try some generic simplifications based on this.
1392 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1396 // If the operation is with the result of a select instruction, check whether
1397 // operating on either branch of the select always yields the same value.
1398 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1399 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1403 // If the operation is with the result of a phi instruction, check whether
1404 // operating on all incoming values of the phi always yields the same value.
1405 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1406 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1413 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout *TD,
1414 const TargetLibraryInfo *TLI,
1415 const DominatorTree *DT) {
1416 return ::SimplifyAndInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1419 /// SimplifyOrInst - Given operands for an Or, see if we can
1420 /// fold the result. If not, this returns null.
1421 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
1422 unsigned MaxRecurse) {
1423 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1424 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1425 Constant *Ops[] = { CLHS, CRHS };
1426 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1430 // Canonicalize the constant to the RHS.
1431 std::swap(Op0, Op1);
1435 if (match(Op1, m_Undef()))
1436 return Constant::getAllOnesValue(Op0->getType());
1443 if (match(Op1, m_Zero()))
1447 if (match(Op1, m_AllOnes()))
1450 // A | ~A = ~A | A = -1
1451 if (match(Op0, m_Not(m_Specific(Op1))) ||
1452 match(Op1, m_Not(m_Specific(Op0))))
1453 return Constant::getAllOnesValue(Op0->getType());
1456 Value *A = 0, *B = 0;
1457 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1458 (A == Op1 || B == Op1))
1462 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1463 (A == Op0 || B == Op0))
1466 // ~(A & ?) | A = -1
1467 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1468 (A == Op1 || B == Op1))
1469 return Constant::getAllOnesValue(Op1->getType());
1471 // A | ~(A & ?) = -1
1472 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1473 (A == Op0 || B == Op0))
1474 return Constant::getAllOnesValue(Op0->getType());
1476 // Try some generic simplifications for associative operations.
1477 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1481 // Or distributes over And. Try some generic simplifications based on this.
1482 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1486 // And distributes over Or. Try some generic simplifications based on this.
1487 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1491 // If the operation is with the result of a select instruction, check whether
1492 // operating on either branch of the select always yields the same value.
1493 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1494 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1498 // If the operation is with the result of a phi instruction, check whether
1499 // operating on all incoming values of the phi always yields the same value.
1500 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1501 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1507 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const DataLayout *TD,
1508 const TargetLibraryInfo *TLI,
1509 const DominatorTree *DT) {
1510 return ::SimplifyOrInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1513 /// SimplifyXorInst - Given operands for a Xor, see if we can
1514 /// fold the result. If not, this returns null.
1515 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q,
1516 unsigned MaxRecurse) {
1517 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1518 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1519 Constant *Ops[] = { CLHS, CRHS };
1520 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1524 // Canonicalize the constant to the RHS.
1525 std::swap(Op0, Op1);
1528 // A ^ undef -> undef
1529 if (match(Op1, m_Undef()))
1533 if (match(Op1, m_Zero()))
1538 return Constant::getNullValue(Op0->getType());
1540 // A ^ ~A = ~A ^ A = -1
1541 if (match(Op0, m_Not(m_Specific(Op1))) ||
1542 match(Op1, m_Not(m_Specific(Op0))))
1543 return Constant::getAllOnesValue(Op0->getType());
1545 // Try some generic simplifications for associative operations.
1546 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1550 // And distributes over Xor. Try some generic simplifications based on this.
1551 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1555 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1556 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1557 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1558 // only if B and C are equal. If B and C are equal then (since we assume
1559 // that operands have already been simplified) "select(cond, B, C)" should
1560 // have been simplified to the common value of B and C already. Analysing
1561 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1562 // for threading over phi nodes.
1567 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const DataLayout *TD,
1568 const TargetLibraryInfo *TLI,
1569 const DominatorTree *DT) {
1570 return ::SimplifyXorInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1573 static Type *GetCompareTy(Value *Op) {
1574 return CmpInst::makeCmpResultType(Op->getType());
1577 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1578 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1579 /// otherwise return null. Helper function for analyzing max/min idioms.
1580 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1581 Value *LHS, Value *RHS) {
1582 SelectInst *SI = dyn_cast<SelectInst>(V);
1585 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1588 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1589 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1591 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1592 LHS == CmpRHS && RHS == CmpLHS)
1597 static Constant *computePointerICmp(const DataLayout &TD,
1598 CmpInst::Predicate Pred,
1599 Value *LHS, Value *RHS) {
1600 // We can only fold certain predicates on pointer comparisons.
1605 // Equality comaprisons are easy to fold.
1606 case CmpInst::ICMP_EQ:
1607 case CmpInst::ICMP_NE:
1610 // We can only handle unsigned relational comparisons because 'inbounds' on
1611 // a GEP only protects against unsigned wrapping.
1612 case CmpInst::ICMP_UGT:
1613 case CmpInst::ICMP_UGE:
1614 case CmpInst::ICMP_ULT:
1615 case CmpInst::ICMP_ULE:
1616 // However, we have to switch them to their signed variants to handle
1617 // negative indices from the base pointer.
1618 Pred = ICmpInst::getSignedPredicate(Pred);
1622 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
1625 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
1629 // If LHS and RHS are not related via constant offsets to the same base
1630 // value, there is nothing we can do here.
1634 return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
1637 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1638 /// fold the result. If not, this returns null.
1639 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1640 const Query &Q, unsigned MaxRecurse) {
1641 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1642 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1644 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1645 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1646 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI);
1648 // If we have a constant, make sure it is on the RHS.
1649 std::swap(LHS, RHS);
1650 Pred = CmpInst::getSwappedPredicate(Pred);
1653 Type *ITy = GetCompareTy(LHS); // The return type.
1654 Type *OpTy = LHS->getType(); // The operand type.
1656 // icmp X, X -> true/false
1657 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1658 // because X could be 0.
1659 if (LHS == RHS || isa<UndefValue>(RHS))
1660 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1662 // Special case logic when the operands have i1 type.
1663 if (OpTy->getScalarType()->isIntegerTy(1)) {
1666 case ICmpInst::ICMP_EQ:
1668 if (match(RHS, m_One()))
1671 case ICmpInst::ICMP_NE:
1673 if (match(RHS, m_Zero()))
1676 case ICmpInst::ICMP_UGT:
1678 if (match(RHS, m_Zero()))
1681 case ICmpInst::ICMP_UGE:
1683 if (match(RHS, m_One()))
1686 case ICmpInst::ICMP_SLT:
1688 if (match(RHS, m_Zero()))
1691 case ICmpInst::ICMP_SLE:
1693 if (match(RHS, m_One()))
1699 // icmp <object*>, <object*/null> - Different identified objects have
1700 // different addresses (unless null), and what's more the address of an
1701 // identified local is never equal to another argument (again, barring null).
1702 // Note that generalizing to the case where LHS is a global variable address
1703 // or null is pointless, since if both LHS and RHS are constants then we
1704 // already constant folded the compare, and if only one of them is then we
1705 // moved it to RHS already.
1706 Value *LHSPtr = LHS->stripPointerCasts();
1707 Value *RHSPtr = RHS->stripPointerCasts();
1708 if (LHSPtr == RHSPtr)
1709 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1711 // Be more aggressive about stripping pointer adjustments when checking a
1712 // comparison of an alloca address to another object. We can rip off all
1713 // inbounds GEP operations, even if they are variable.
1714 LHSPtr = LHSPtr->stripInBoundsOffsets();
1715 if (llvm::isIdentifiedObject(LHSPtr)) {
1716 RHSPtr = RHSPtr->stripInBoundsOffsets();
1717 if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) {
1718 // If both sides are different identified objects, they aren't equal
1719 // unless they're null.
1720 if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) &&
1721 Pred == CmpInst::ICMP_EQ)
1722 return ConstantInt::get(ITy, false);
1724 // A local identified object (alloca or noalias call) can't equal any
1725 // incoming argument, unless they're both null or they belong to
1726 // different functions. The latter happens during inlining.
1727 if (Instruction *LHSInst = dyn_cast<Instruction>(LHSPtr))
1728 if (Argument *RHSArg = dyn_cast<Argument>(RHSPtr))
1729 if (LHSInst->getParent()->getParent() == RHSArg->getParent() &&
1730 Pred == CmpInst::ICMP_EQ)
1731 return ConstantInt::get(ITy, false);
1734 // Assume that the constant null is on the right.
1735 if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) {
1736 if (Pred == CmpInst::ICMP_EQ)
1737 return ConstantInt::get(ITy, false);
1738 else if (Pred == CmpInst::ICMP_NE)
1739 return ConstantInt::get(ITy, true);
1741 } else if (Argument *LHSArg = dyn_cast<Argument>(LHSPtr)) {
1742 RHSPtr = RHSPtr->stripInBoundsOffsets();
1743 // An alloca can't be equal to an argument unless they come from separate
1744 // functions via inlining.
1745 if (AllocaInst *RHSInst = dyn_cast<AllocaInst>(RHSPtr)) {
1746 if (LHSArg->getParent() == RHSInst->getParent()->getParent()) {
1747 if (Pred == CmpInst::ICMP_EQ)
1748 return ConstantInt::get(ITy, false);
1749 else if (Pred == CmpInst::ICMP_NE)
1750 return ConstantInt::get(ITy, true);
1755 // If we are comparing with zero then try hard since this is a common case.
1756 if (match(RHS, m_Zero())) {
1757 bool LHSKnownNonNegative, LHSKnownNegative;
1759 default: llvm_unreachable("Unknown ICmp predicate!");
1760 case ICmpInst::ICMP_ULT:
1761 return getFalse(ITy);
1762 case ICmpInst::ICMP_UGE:
1763 return getTrue(ITy);
1764 case ICmpInst::ICMP_EQ:
1765 case ICmpInst::ICMP_ULE:
1766 if (isKnownNonZero(LHS, Q.TD))
1767 return getFalse(ITy);
1769 case ICmpInst::ICMP_NE:
1770 case ICmpInst::ICMP_UGT:
1771 if (isKnownNonZero(LHS, Q.TD))
1772 return getTrue(ITy);
1774 case ICmpInst::ICMP_SLT:
1775 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1776 if (LHSKnownNegative)
1777 return getTrue(ITy);
1778 if (LHSKnownNonNegative)
1779 return getFalse(ITy);
1781 case ICmpInst::ICMP_SLE:
1782 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1783 if (LHSKnownNegative)
1784 return getTrue(ITy);
1785 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
1786 return getFalse(ITy);
1788 case ICmpInst::ICMP_SGE:
1789 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1790 if (LHSKnownNegative)
1791 return getFalse(ITy);
1792 if (LHSKnownNonNegative)
1793 return getTrue(ITy);
1795 case ICmpInst::ICMP_SGT:
1796 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1797 if (LHSKnownNegative)
1798 return getFalse(ITy);
1799 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
1800 return getTrue(ITy);
1805 // See if we are doing a comparison with a constant integer.
1806 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1807 // Rule out tautological comparisons (eg., ult 0 or uge 0).
1808 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
1809 if (RHS_CR.isEmptySet())
1810 return ConstantInt::getFalse(CI->getContext());
1811 if (RHS_CR.isFullSet())
1812 return ConstantInt::getTrue(CI->getContext());
1814 // Many binary operators with constant RHS have easy to compute constant
1815 // range. Use them to check whether the comparison is a tautology.
1816 uint32_t Width = CI->getBitWidth();
1817 APInt Lower = APInt(Width, 0);
1818 APInt Upper = APInt(Width, 0);
1820 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
1821 // 'urem x, CI2' produces [0, CI2).
1822 Upper = CI2->getValue();
1823 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
1824 // 'srem x, CI2' produces (-|CI2|, |CI2|).
1825 Upper = CI2->getValue().abs();
1826 Lower = (-Upper) + 1;
1827 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
1828 // 'udiv CI2, x' produces [0, CI2].
1829 Upper = CI2->getValue() + 1;
1830 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
1831 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
1832 APInt NegOne = APInt::getAllOnesValue(Width);
1834 Upper = NegOne.udiv(CI2->getValue()) + 1;
1835 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
1836 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
1837 APInt IntMin = APInt::getSignedMinValue(Width);
1838 APInt IntMax = APInt::getSignedMaxValue(Width);
1839 APInt Val = CI2->getValue().abs();
1840 if (!Val.isMinValue()) {
1841 Lower = IntMin.sdiv(Val);
1842 Upper = IntMax.sdiv(Val) + 1;
1844 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
1845 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
1846 APInt NegOne = APInt::getAllOnesValue(Width);
1847 if (CI2->getValue().ult(Width))
1848 Upper = NegOne.lshr(CI2->getValue()) + 1;
1849 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
1850 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
1851 APInt IntMin = APInt::getSignedMinValue(Width);
1852 APInt IntMax = APInt::getSignedMaxValue(Width);
1853 if (CI2->getValue().ult(Width)) {
1854 Lower = IntMin.ashr(CI2->getValue());
1855 Upper = IntMax.ashr(CI2->getValue()) + 1;
1857 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
1858 // 'or x, CI2' produces [CI2, UINT_MAX].
1859 Lower = CI2->getValue();
1860 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
1861 // 'and x, CI2' produces [0, CI2].
1862 Upper = CI2->getValue() + 1;
1864 if (Lower != Upper) {
1865 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
1866 if (RHS_CR.contains(LHS_CR))
1867 return ConstantInt::getTrue(RHS->getContext());
1868 if (RHS_CR.inverse().contains(LHS_CR))
1869 return ConstantInt::getFalse(RHS->getContext());
1873 // Compare of cast, for example (zext X) != 0 -> X != 0
1874 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1875 Instruction *LI = cast<CastInst>(LHS);
1876 Value *SrcOp = LI->getOperand(0);
1877 Type *SrcTy = SrcOp->getType();
1878 Type *DstTy = LI->getType();
1880 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1881 // if the integer type is the same size as the pointer type.
1882 if (MaxRecurse && Q.TD && isa<PtrToIntInst>(LI) &&
1883 Q.TD->getPointerSizeInBits(
1884 cast<PtrToIntInst>(LI)->getPointerAddressSpace()) ==
1885 DstTy->getPrimitiveSizeInBits()) {
1886 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1887 // Transfer the cast to the constant.
1888 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1889 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1892 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1893 if (RI->getOperand(0)->getType() == SrcTy)
1894 // Compare without the cast.
1895 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1901 if (isa<ZExtInst>(LHS)) {
1902 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1904 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1905 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1906 // Compare X and Y. Note that signed predicates become unsigned.
1907 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1908 SrcOp, RI->getOperand(0), Q,
1912 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1913 // too. If not, then try to deduce the result of the comparison.
1914 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1915 // Compute the constant that would happen if we truncated to SrcTy then
1916 // reextended to DstTy.
1917 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1918 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1920 // If the re-extended constant didn't change then this is effectively
1921 // also a case of comparing two zero-extended values.
1922 if (RExt == CI && MaxRecurse)
1923 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1924 SrcOp, Trunc, Q, MaxRecurse-1))
1927 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1928 // there. Use this to work out the result of the comparison.
1931 default: llvm_unreachable("Unknown ICmp predicate!");
1933 case ICmpInst::ICMP_EQ:
1934 case ICmpInst::ICMP_UGT:
1935 case ICmpInst::ICMP_UGE:
1936 return ConstantInt::getFalse(CI->getContext());
1938 case ICmpInst::ICMP_NE:
1939 case ICmpInst::ICMP_ULT:
1940 case ICmpInst::ICMP_ULE:
1941 return ConstantInt::getTrue(CI->getContext());
1943 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1944 // is non-negative then LHS <s RHS.
1945 case ICmpInst::ICMP_SGT:
1946 case ICmpInst::ICMP_SGE:
1947 return CI->getValue().isNegative() ?
1948 ConstantInt::getTrue(CI->getContext()) :
1949 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());
1961 if (isa<SExtInst>(LHS)) {
1962 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1964 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1965 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1966 // Compare X and Y. Note that the predicate does not change.
1967 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1971 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1972 // too. If not, then try to deduce the result of the comparison.
1973 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1974 // Compute the constant that would happen if we truncated to SrcTy then
1975 // reextended to DstTy.
1976 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1977 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1979 // If the re-extended constant didn't change then this is effectively
1980 // also a case of comparing two sign-extended values.
1981 if (RExt == CI && MaxRecurse)
1982 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
1985 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1986 // bits there. Use this to work out the result of the comparison.
1989 default: llvm_unreachable("Unknown ICmp predicate!");
1990 case ICmpInst::ICMP_EQ:
1991 return ConstantInt::getFalse(CI->getContext());
1992 case ICmpInst::ICMP_NE:
1993 return ConstantInt::getTrue(CI->getContext());
1995 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1997 case ICmpInst::ICMP_SGT:
1998 case ICmpInst::ICMP_SGE:
1999 return CI->getValue().isNegative() ?
2000 ConstantInt::getTrue(CI->getContext()) :
2001 ConstantInt::getFalse(CI->getContext());
2002 case ICmpInst::ICMP_SLT:
2003 case ICmpInst::ICMP_SLE:
2004 return CI->getValue().isNegative() ?
2005 ConstantInt::getFalse(CI->getContext()) :
2006 ConstantInt::getTrue(CI->getContext());
2008 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
2010 case ICmpInst::ICMP_UGT:
2011 case ICmpInst::ICMP_UGE:
2012 // Comparison is true iff the LHS <s 0.
2014 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
2015 Constant::getNullValue(SrcTy),
2019 case ICmpInst::ICMP_ULT:
2020 case ICmpInst::ICMP_ULE:
2021 // Comparison is true iff the LHS >=s 0.
2023 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
2024 Constant::getNullValue(SrcTy),
2034 // Special logic for binary operators.
2035 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2036 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2037 if (MaxRecurse && (LBO || RBO)) {
2038 // Analyze the case when either LHS or RHS is an add instruction.
2039 Value *A = 0, *B = 0, *C = 0, *D = 0;
2040 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2041 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2042 if (LBO && LBO->getOpcode() == Instruction::Add) {
2043 A = LBO->getOperand(0); B = LBO->getOperand(1);
2044 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
2045 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
2046 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
2048 if (RBO && RBO->getOpcode() == Instruction::Add) {
2049 C = RBO->getOperand(0); D = RBO->getOperand(1);
2050 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
2051 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2052 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2055 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2056 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2057 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2058 Constant::getNullValue(RHS->getType()),
2062 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2063 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2064 if (Value *V = SimplifyICmpInst(Pred,
2065 Constant::getNullValue(LHS->getType()),
2066 C == LHS ? D : C, Q, MaxRecurse-1))
2069 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2070 if (A && C && (A == C || A == D || B == C || B == D) &&
2071 NoLHSWrapProblem && NoRHSWrapProblem) {
2072 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2073 Value *Y = (A == C || A == D) ? B : A;
2074 Value *Z = (C == A || C == B) ? D : C;
2075 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
2080 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2081 bool KnownNonNegative, KnownNegative;
2085 case ICmpInst::ICMP_SGT:
2086 case ICmpInst::ICMP_SGE:
2087 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
2088 if (!KnownNonNegative)
2091 case ICmpInst::ICMP_EQ:
2092 case ICmpInst::ICMP_UGT:
2093 case ICmpInst::ICMP_UGE:
2094 return getFalse(ITy);
2095 case ICmpInst::ICMP_SLT:
2096 case ICmpInst::ICMP_SLE:
2097 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
2098 if (!KnownNonNegative)
2101 case ICmpInst::ICMP_NE:
2102 case ICmpInst::ICMP_ULT:
2103 case ICmpInst::ICMP_ULE:
2104 return getTrue(ITy);
2107 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2108 bool KnownNonNegative, KnownNegative;
2112 case ICmpInst::ICMP_SGT:
2113 case ICmpInst::ICMP_SGE:
2114 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
2115 if (!KnownNonNegative)
2118 case ICmpInst::ICMP_NE:
2119 case ICmpInst::ICMP_UGT:
2120 case ICmpInst::ICMP_UGE:
2121 return getTrue(ITy);
2122 case ICmpInst::ICMP_SLT:
2123 case ICmpInst::ICMP_SLE:
2124 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
2125 if (!KnownNonNegative)
2128 case ICmpInst::ICMP_EQ:
2129 case ICmpInst::ICMP_ULT:
2130 case ICmpInst::ICMP_ULE:
2131 return getFalse(ITy);
2136 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2137 // icmp pred (X /u Y), X
2138 if (Pred == ICmpInst::ICMP_UGT)
2139 return getFalse(ITy);
2140 if (Pred == ICmpInst::ICMP_ULE)
2141 return getTrue(ITy);
2144 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2145 LBO->getOperand(1) == RBO->getOperand(1)) {
2146 switch (LBO->getOpcode()) {
2148 case Instruction::UDiv:
2149 case Instruction::LShr:
2150 if (ICmpInst::isSigned(Pred))
2153 case Instruction::SDiv:
2154 case Instruction::AShr:
2155 if (!LBO->isExact() || !RBO->isExact())
2157 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2158 RBO->getOperand(0), Q, MaxRecurse-1))
2161 case Instruction::Shl: {
2162 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2163 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2166 if (!NSW && ICmpInst::isSigned(Pred))
2168 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2169 RBO->getOperand(0), Q, MaxRecurse-1))
2176 // Simplify comparisons involving max/min.
2178 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2179 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2181 // Signed variants on "max(a,b)>=a -> true".
2182 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2183 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2184 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2185 // We analyze this as smax(A, B) pred A.
2187 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2188 (A == LHS || B == LHS)) {
2189 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2190 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2191 // We analyze this as smax(A, B) swapped-pred A.
2192 P = CmpInst::getSwappedPredicate(Pred);
2193 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2194 (A == RHS || B == RHS)) {
2195 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2196 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2197 // We analyze this as smax(-A, -B) swapped-pred -A.
2198 // Note that we do not need to actually form -A or -B thanks to EqP.
2199 P = CmpInst::getSwappedPredicate(Pred);
2200 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2201 (A == LHS || B == LHS)) {
2202 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2203 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2204 // We analyze this as smax(-A, -B) pred -A.
2205 // Note that we do not need to actually form -A or -B thanks to EqP.
2208 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2209 // Cases correspond to "max(A, B) p A".
2213 case CmpInst::ICMP_EQ:
2214 case CmpInst::ICMP_SLE:
2215 // Equivalent to "A EqP B". This may be the same as the condition tested
2216 // in the max/min; if so, we can just return that.
2217 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2219 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2221 // Otherwise, see if "A EqP B" simplifies.
2223 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2226 case CmpInst::ICMP_NE:
2227 case CmpInst::ICMP_SGT: {
2228 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2229 // Equivalent to "A InvEqP B". This may be the same as the condition
2230 // tested in the max/min; if so, we can just return that.
2231 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2233 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2235 // Otherwise, see if "A InvEqP B" simplifies.
2237 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2241 case CmpInst::ICMP_SGE:
2243 return getTrue(ITy);
2244 case CmpInst::ICMP_SLT:
2246 return getFalse(ITy);
2250 // Unsigned variants on "max(a,b)>=a -> true".
2251 P = CmpInst::BAD_ICMP_PREDICATE;
2252 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2253 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2254 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2255 // We analyze this as umax(A, B) pred A.
2257 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2258 (A == LHS || B == LHS)) {
2259 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2260 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2261 // We analyze this as umax(A, B) swapped-pred A.
2262 P = CmpInst::getSwappedPredicate(Pred);
2263 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2264 (A == RHS || B == RHS)) {
2265 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2266 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2267 // We analyze this as umax(-A, -B) swapped-pred -A.
2268 // Note that we do not need to actually form -A or -B thanks to EqP.
2269 P = CmpInst::getSwappedPredicate(Pred);
2270 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2271 (A == LHS || B == LHS)) {
2272 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2273 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2274 // We analyze this as umax(-A, -B) pred -A.
2275 // Note that we do not need to actually form -A or -B thanks to EqP.
2278 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2279 // Cases correspond to "max(A, B) p A".
2283 case CmpInst::ICMP_EQ:
2284 case CmpInst::ICMP_ULE:
2285 // Equivalent to "A EqP B". This may be the same as the condition tested
2286 // in the max/min; if so, we can just return that.
2287 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2289 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2291 // Otherwise, see if "A EqP B" simplifies.
2293 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2296 case CmpInst::ICMP_NE:
2297 case CmpInst::ICMP_UGT: {
2298 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2299 // Equivalent to "A InvEqP B". This may be the same as the condition
2300 // tested in the max/min; if so, we can just return that.
2301 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2303 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2305 // Otherwise, see if "A InvEqP B" simplifies.
2307 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2311 case CmpInst::ICMP_UGE:
2313 return getTrue(ITy);
2314 case CmpInst::ICMP_ULT:
2316 return getFalse(ITy);
2320 // Variants on "max(x,y) >= min(x,z)".
2322 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2323 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2324 (A == C || A == D || B == C || B == D)) {
2325 // max(x, ?) pred min(x, ?).
2326 if (Pred == CmpInst::ICMP_SGE)
2328 return getTrue(ITy);
2329 if (Pred == CmpInst::ICMP_SLT)
2331 return getFalse(ITy);
2332 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2333 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2334 (A == C || A == D || B == C || B == D)) {
2335 // min(x, ?) pred max(x, ?).
2336 if (Pred == CmpInst::ICMP_SLE)
2338 return getTrue(ITy);
2339 if (Pred == CmpInst::ICMP_SGT)
2341 return getFalse(ITy);
2342 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2343 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2344 (A == C || A == D || B == C || B == D)) {
2345 // max(x, ?) pred min(x, ?).
2346 if (Pred == CmpInst::ICMP_UGE)
2348 return getTrue(ITy);
2349 if (Pred == CmpInst::ICMP_ULT)
2351 return getFalse(ITy);
2352 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2353 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2354 (A == C || A == D || B == C || B == D)) {
2355 // min(x, ?) pred max(x, ?).
2356 if (Pred == CmpInst::ICMP_ULE)
2358 return getTrue(ITy);
2359 if (Pred == CmpInst::ICMP_UGT)
2361 return getFalse(ITy);
2364 // Simplify comparisons of related pointers using a powerful, recursive
2365 // GEP-walk when we have target data available..
2366 if (Q.TD && LHS->getType()->isPointerTy() && RHS->getType()->isPointerTy())
2367 if (Constant *C = computePointerICmp(*Q.TD, Pred, LHS, RHS))
2370 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
2371 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
2372 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
2373 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
2374 (ICmpInst::isEquality(Pred) ||
2375 (GLHS->isInBounds() && GRHS->isInBounds() &&
2376 Pred == ICmpInst::getSignedPredicate(Pred)))) {
2377 // The bases are equal and the indices are constant. Build a constant
2378 // expression GEP with the same indices and a null base pointer to see
2379 // what constant folding can make out of it.
2380 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
2381 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
2382 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS);
2384 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
2385 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS);
2386 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
2391 // If the comparison is with the result of a select instruction, check whether
2392 // comparing with either branch of the select always yields the same value.
2393 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2394 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2397 // If the comparison is with the result of a phi instruction, check whether
2398 // doing the compare with each incoming phi value yields a common result.
2399 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2400 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2406 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2407 const DataLayout *TD,
2408 const TargetLibraryInfo *TLI,
2409 const DominatorTree *DT) {
2410 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2414 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
2415 /// fold the result. If not, this returns null.
2416 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2417 const Query &Q, unsigned MaxRecurse) {
2418 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2419 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
2421 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2422 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2423 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI);
2425 // If we have a constant, make sure it is on the RHS.
2426 std::swap(LHS, RHS);
2427 Pred = CmpInst::getSwappedPredicate(Pred);
2430 // Fold trivial predicates.
2431 if (Pred == FCmpInst::FCMP_FALSE)
2432 return ConstantInt::get(GetCompareTy(LHS), 0);
2433 if (Pred == FCmpInst::FCMP_TRUE)
2434 return ConstantInt::get(GetCompareTy(LHS), 1);
2436 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
2437 return UndefValue::get(GetCompareTy(LHS));
2439 // fcmp x,x -> true/false. Not all compares are foldable.
2441 if (CmpInst::isTrueWhenEqual(Pred))
2442 return ConstantInt::get(GetCompareTy(LHS), 1);
2443 if (CmpInst::isFalseWhenEqual(Pred))
2444 return ConstantInt::get(GetCompareTy(LHS), 0);
2447 // Handle fcmp with constant RHS
2448 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2449 // If the constant is a nan, see if we can fold the comparison based on it.
2450 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2451 if (CFP->getValueAPF().isNaN()) {
2452 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
2453 return ConstantInt::getFalse(CFP->getContext());
2454 assert(FCmpInst::isUnordered(Pred) &&
2455 "Comparison must be either ordered or unordered!");
2456 // True if unordered.
2457 return ConstantInt::getTrue(CFP->getContext());
2459 // Check whether the constant is an infinity.
2460 if (CFP->getValueAPF().isInfinity()) {
2461 if (CFP->getValueAPF().isNegative()) {
2463 case FCmpInst::FCMP_OLT:
2464 // No value is ordered and less than negative infinity.
2465 return ConstantInt::getFalse(CFP->getContext());
2466 case FCmpInst::FCMP_UGE:
2467 // All values are unordered with or at least negative infinity.
2468 return ConstantInt::getTrue(CFP->getContext());
2474 case FCmpInst::FCMP_OGT:
2475 // No value is ordered and greater than infinity.
2476 return ConstantInt::getFalse(CFP->getContext());
2477 case FCmpInst::FCMP_ULE:
2478 // All values are unordered with and at most infinity.
2479 return ConstantInt::getTrue(CFP->getContext());
2488 // If the comparison is with the result of a select instruction, check whether
2489 // comparing with either branch of the select always yields the same value.
2490 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2491 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2494 // If the comparison is with the result of a phi instruction, check whether
2495 // doing the compare with each incoming phi value yields a common result.
2496 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2497 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2503 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2504 const DataLayout *TD,
2505 const TargetLibraryInfo *TLI,
2506 const DominatorTree *DT) {
2507 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2511 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
2512 /// the result. If not, this returns null.
2513 static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
2514 Value *FalseVal, const Query &Q,
2515 unsigned MaxRecurse) {
2516 // select true, X, Y -> X
2517 // select false, X, Y -> Y
2518 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
2519 return CB->getZExtValue() ? TrueVal : FalseVal;
2521 // select C, X, X -> X
2522 if (TrueVal == FalseVal)
2525 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
2526 if (isa<Constant>(TrueVal))
2530 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
2532 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
2538 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
2539 const DataLayout *TD,
2540 const TargetLibraryInfo *TLI,
2541 const DominatorTree *DT) {
2542 return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Query (TD, TLI, DT),
2546 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
2547 /// fold the result. If not, this returns null.
2548 static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) {
2549 // The type of the GEP pointer operand.
2550 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType());
2551 // The GEP pointer operand is not a pointer, it's a vector of pointers.
2555 // getelementptr P -> P.
2556 if (Ops.size() == 1)
2559 if (isa<UndefValue>(Ops[0])) {
2560 // Compute the (pointer) type returned by the GEP instruction.
2561 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
2562 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
2563 return UndefValue::get(GEPTy);
2566 if (Ops.size() == 2) {
2567 // getelementptr P, 0 -> P.
2568 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
2571 // getelementptr P, N -> P if P points to a type of zero size.
2573 Type *Ty = PtrTy->getElementType();
2574 if (Ty->isSized() && Q.TD->getTypeAllocSize(Ty) == 0)
2579 // Check to see if this is constant foldable.
2580 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2581 if (!isa<Constant>(Ops[i]))
2584 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
2587 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const DataLayout *TD,
2588 const TargetLibraryInfo *TLI,
2589 const DominatorTree *DT) {
2590 return ::SimplifyGEPInst(Ops, Query (TD, TLI, DT), RecursionLimit);
2593 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
2594 /// can fold the result. If not, this returns null.
2595 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
2596 ArrayRef<unsigned> Idxs, const Query &Q,
2598 if (Constant *CAgg = dyn_cast<Constant>(Agg))
2599 if (Constant *CVal = dyn_cast<Constant>(Val))
2600 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
2602 // insertvalue x, undef, n -> x
2603 if (match(Val, m_Undef()))
2606 // insertvalue x, (extractvalue y, n), n
2607 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
2608 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
2609 EV->getIndices() == Idxs) {
2610 // insertvalue undef, (extractvalue y, n), n -> y
2611 if (match(Agg, m_Undef()))
2612 return EV->getAggregateOperand();
2614 // insertvalue y, (extractvalue y, n), n -> y
2615 if (Agg == EV->getAggregateOperand())
2622 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
2623 ArrayRef<unsigned> Idxs,
2624 const DataLayout *TD,
2625 const TargetLibraryInfo *TLI,
2626 const DominatorTree *DT) {
2627 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query (TD, TLI, DT),
2631 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
2632 static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
2633 // If all of the PHI's incoming values are the same then replace the PHI node
2634 // with the common value.
2635 Value *CommonValue = 0;
2636 bool HasUndefInput = false;
2637 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
2638 Value *Incoming = PN->getIncomingValue(i);
2639 // If the incoming value is the phi node itself, it can safely be skipped.
2640 if (Incoming == PN) continue;
2641 if (isa<UndefValue>(Incoming)) {
2642 // Remember that we saw an undef value, but otherwise ignore them.
2643 HasUndefInput = true;
2646 if (CommonValue && Incoming != CommonValue)
2647 return 0; // Not the same, bail out.
2648 CommonValue = Incoming;
2651 // If CommonValue is null then all of the incoming values were either undef or
2652 // equal to the phi node itself.
2654 return UndefValue::get(PN->getType());
2656 // If we have a PHI node like phi(X, undef, X), where X is defined by some
2657 // instruction, we cannot return X as the result of the PHI node unless it
2658 // dominates the PHI block.
2660 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : 0;
2665 static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) {
2666 if (Constant *C = dyn_cast<Constant>(Op))
2667 return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.TD, Q.TLI);
2672 Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const DataLayout *TD,
2673 const TargetLibraryInfo *TLI,
2674 const DominatorTree *DT) {
2675 return ::SimplifyTruncInst(Op, Ty, Query (TD, TLI, DT), RecursionLimit);
2678 //=== Helper functions for higher up the class hierarchy.
2680 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
2681 /// fold the result. If not, this returns null.
2682 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2683 const Query &Q, unsigned MaxRecurse) {
2685 case Instruction::Add:
2686 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2688 case Instruction::Sub:
2689 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2691 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
2692 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
2693 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
2694 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse);
2695 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
2696 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
2697 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse);
2698 case Instruction::Shl:
2699 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2701 case Instruction::LShr:
2702 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
2703 case Instruction::AShr:
2704 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
2705 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
2706 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
2707 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
2709 if (Constant *CLHS = dyn_cast<Constant>(LHS))
2710 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
2711 Constant *COps[] = {CLHS, CRHS};
2712 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.TD,
2716 // If the operation is associative, try some generic simplifications.
2717 if (Instruction::isAssociative(Opcode))
2718 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
2721 // If the operation is with the result of a select instruction check whether
2722 // operating on either branch of the select always yields the same value.
2723 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2724 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
2727 // If the operation is with the result of a phi instruction, check whether
2728 // operating on all incoming values of the phi always yields the same value.
2729 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2730 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
2737 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2738 const DataLayout *TD, const TargetLibraryInfo *TLI,
2739 const DominatorTree *DT) {
2740 return ::SimplifyBinOp(Opcode, LHS, RHS, Query (TD, TLI, DT), RecursionLimit);
2743 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
2744 /// fold the result.
2745 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2746 const Query &Q, unsigned MaxRecurse) {
2747 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
2748 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
2749 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
2752 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2753 const DataLayout *TD, const TargetLibraryInfo *TLI,
2754 const DominatorTree *DT) {
2755 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2759 static Value *SimplifyCallInst(CallInst *CI, const Query &) {
2760 // call undef -> undef
2761 if (isa<UndefValue>(CI->getCalledValue()))
2762 return UndefValue::get(CI->getType());
2767 /// SimplifyInstruction - See if we can compute a simplified version of this
2768 /// instruction. If not, this returns null.
2769 Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *TD,
2770 const TargetLibraryInfo *TLI,
2771 const DominatorTree *DT) {
2774 switch (I->getOpcode()) {
2776 Result = ConstantFoldInstruction(I, TD, TLI);
2778 case Instruction::Add:
2779 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
2780 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2781 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2784 case Instruction::Sub:
2785 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
2786 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2787 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2790 case Instruction::Mul:
2791 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2793 case Instruction::SDiv:
2794 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2796 case Instruction::UDiv:
2797 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2799 case Instruction::FDiv:
2800 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2802 case Instruction::SRem:
2803 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2805 case Instruction::URem:
2806 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2808 case Instruction::FRem:
2809 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2811 case Instruction::Shl:
2812 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
2813 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2814 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2817 case Instruction::LShr:
2818 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
2819 cast<BinaryOperator>(I)->isExact(),
2822 case Instruction::AShr:
2823 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
2824 cast<BinaryOperator>(I)->isExact(),
2827 case Instruction::And:
2828 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2830 case Instruction::Or:
2831 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2833 case Instruction::Xor:
2834 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2836 case Instruction::ICmp:
2837 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
2838 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2840 case Instruction::FCmp:
2841 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
2842 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2844 case Instruction::Select:
2845 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
2846 I->getOperand(2), TD, TLI, DT);
2848 case Instruction::GetElementPtr: {
2849 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
2850 Result = SimplifyGEPInst(Ops, TD, TLI, DT);
2853 case Instruction::InsertValue: {
2854 InsertValueInst *IV = cast<InsertValueInst>(I);
2855 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
2856 IV->getInsertedValueOperand(),
2857 IV->getIndices(), TD, TLI, DT);
2860 case Instruction::PHI:
2861 Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT));
2863 case Instruction::Call:
2864 Result = SimplifyCallInst(cast<CallInst>(I), Query (TD, TLI, DT));
2866 case Instruction::Trunc:
2867 Result = SimplifyTruncInst(I->getOperand(0), I->getType(), TD, TLI, DT);
2871 /// If called on unreachable code, the above logic may report that the
2872 /// instruction simplified to itself. Make life easier for users by
2873 /// detecting that case here, returning a safe value instead.
2874 return Result == I ? UndefValue::get(I->getType()) : Result;
2877 /// \brief Implementation of recursive simplification through an instructions
2880 /// This is the common implementation of the recursive simplification routines.
2881 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
2882 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
2883 /// instructions to process and attempt to simplify it using
2884 /// InstructionSimplify.
2886 /// This routine returns 'true' only when *it* simplifies something. The passed
2887 /// in simplified value does not count toward this.
2888 static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
2889 const DataLayout *TD,
2890 const TargetLibraryInfo *TLI,
2891 const DominatorTree *DT) {
2892 bool Simplified = false;
2893 SmallSetVector<Instruction *, 8> Worklist;
2895 // If we have an explicit value to collapse to, do that round of the
2896 // simplification loop by hand initially.
2898 for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
2901 Worklist.insert(cast<Instruction>(*UI));
2903 // Replace the instruction with its simplified value.
2904 I->replaceAllUsesWith(SimpleV);
2906 // Gracefully handle edge cases where the instruction is not wired into any
2909 I->eraseFromParent();
2914 // Note that we must test the size on each iteration, the worklist can grow.
2915 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
2918 // See if this instruction simplifies.
2919 SimpleV = SimplifyInstruction(I, TD, TLI, DT);
2925 // Stash away all the uses of the old instruction so we can check them for
2926 // recursive simplifications after a RAUW. This is cheaper than checking all
2927 // uses of To on the recursive step in most cases.
2928 for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
2930 Worklist.insert(cast<Instruction>(*UI));
2932 // Replace the instruction with its simplified value.
2933 I->replaceAllUsesWith(SimpleV);
2935 // Gracefully handle edge cases where the instruction is not wired into any
2938 I->eraseFromParent();
2943 bool llvm::recursivelySimplifyInstruction(Instruction *I,
2944 const DataLayout *TD,
2945 const TargetLibraryInfo *TLI,
2946 const DominatorTree *DT) {
2947 return replaceAndRecursivelySimplifyImpl(I, 0, TD, TLI, DT);
2950 bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
2951 const DataLayout *TD,
2952 const TargetLibraryInfo *TLI,
2953 const DominatorTree *DT) {
2954 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
2955 assert(SimpleV && "Must provide a simplified value.");
2956 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TD, TLI, DT);