1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements routines for folding instructions into simpler forms
11 // that do not require creating new instructions. This does constant folding
12 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
13 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
14 // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
15 // simplified: This is usually true and assuming it simplifies the logic (if
16 // they have not been simplified then results are correct but maybe suboptimal).
18 //===----------------------------------------------------------------------===//
20 #define DEBUG_TYPE "instsimplify"
21 #include "llvm/GlobalAlias.h"
22 #include "llvm/Operator.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/Analysis/InstructionSimplify.h"
25 #include "llvm/Analysis/AliasAnalysis.h"
26 #include "llvm/Analysis/ConstantFolding.h"
27 #include "llvm/Analysis/Dominators.h"
28 #include "llvm/Analysis/ValueTracking.h"
29 #include "llvm/Support/ConstantRange.h"
30 #include "llvm/Support/GetElementPtrTypeIterator.h"
31 #include "llvm/Support/PatternMatch.h"
32 #include "llvm/Support/ValueHandle.h"
33 #include "llvm/Target/TargetData.h"
35 using namespace llvm::PatternMatch;
37 enum { RecursionLimit = 3 };
39 STATISTIC(NumExpand, "Number of expansions");
40 STATISTIC(NumFactor , "Number of factorizations");
41 STATISTIC(NumReassoc, "Number of reassociations");
45 const TargetLibraryInfo *TLI;
46 const DominatorTree *DT;
48 Query(const TargetData *td, const TargetLibraryInfo *tli,
49 const DominatorTree *dt) : TD(td), TLI(tli), DT(dt) {};
52 static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
53 static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
55 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
57 static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
58 static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
60 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
61 /// a vector with every element false, as appropriate for the type.
62 static Constant *getFalse(Type *Ty) {
63 assert(Ty->getScalarType()->isIntegerTy(1) &&
64 "Expected i1 type or a vector of i1!");
65 return Constant::getNullValue(Ty);
68 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
69 /// a vector with every element true, as appropriate for the type.
70 static Constant *getTrue(Type *Ty) {
71 assert(Ty->getScalarType()->isIntegerTy(1) &&
72 "Expected i1 type or a vector of i1!");
73 return Constant::getAllOnesValue(Ty);
76 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
77 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
79 CmpInst *Cmp = dyn_cast<CmpInst>(V);
82 CmpInst::Predicate CPred = Cmp->getPredicate();
83 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
84 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
86 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
90 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
91 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
92 Instruction *I = dyn_cast<Instruction>(V);
94 // Arguments and constants dominate all instructions.
97 // If we have a DominatorTree then do a precise test.
99 if (!DT->isReachableFromEntry(P->getParent()))
101 if (!DT->isReachableFromEntry(I->getParent()))
103 return DT->dominates(I, P);
106 // Otherwise, if the instruction is in the entry block, and is not an invoke,
107 // then it obviously dominates all phi nodes.
108 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
115 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
116 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
117 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
118 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
119 /// Returns the simplified value, or null if no simplification was performed.
120 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
121 unsigned OpcToExpand, const Query &Q,
122 unsigned MaxRecurse) {
123 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
124 // Recursion is always used, so bail out at once if we already hit the limit.
128 // Check whether the expression has the form "(A op' B) op C".
129 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
130 if (Op0->getOpcode() == OpcodeToExpand) {
131 // It does! Try turning it into "(A op C) op' (B op C)".
132 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
133 // Do "A op C" and "B op C" both simplify?
134 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
135 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
136 // They do! Return "L op' R" if it simplifies or is already available.
137 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
138 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
139 && L == B && R == A)) {
143 // Otherwise return "L op' R" if it simplifies.
144 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
151 // Check whether the expression has the form "A op (B op' C)".
152 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
153 if (Op1->getOpcode() == OpcodeToExpand) {
154 // It does! Try turning it into "(A op B) op' (A op C)".
155 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
156 // Do "A op B" and "A op C" both simplify?
157 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
158 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
159 // They do! Return "L op' R" if it simplifies or is already available.
160 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
161 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
162 && L == C && R == B)) {
166 // Otherwise return "L op' R" if it simplifies.
167 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
177 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
178 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
179 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
180 /// Returns the simplified value, or null if no simplification was performed.
181 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
182 unsigned OpcToExtract, const Query &Q,
183 unsigned MaxRecurse) {
184 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
185 // Recursion is always used, so bail out at once if we already hit the limit.
189 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
190 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
192 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
193 !Op1 || Op1->getOpcode() != OpcodeToExtract)
196 // The expression has the form "(A op' B) op (C op' D)".
197 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
198 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
200 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
201 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
202 // commutative case, "(A op' B) op (C op' A)"?
203 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
204 Value *DD = A == C ? D : C;
205 // Form "A op' (B op DD)" if it simplifies completely.
206 // Does "B op DD" simplify?
207 if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) {
208 // It does! Return "A op' V" if it simplifies or is already available.
209 // If V equals B then "A op' V" is just the LHS. If V equals DD then
210 // "A op' V" is just the RHS.
211 if (V == B || V == DD) {
213 return V == B ? LHS : RHS;
215 // Otherwise return "A op' V" if it simplifies.
216 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) {
223 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
224 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
225 // commutative case, "(A op' B) op (B op' D)"?
226 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
227 Value *CC = B == D ? C : D;
228 // Form "(A op CC) op' B" if it simplifies completely..
229 // Does "A op CC" simplify?
230 if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) {
231 // It does! Return "V op' B" if it simplifies or is already available.
232 // If V equals A then "V op' B" is just the LHS. If V equals CC then
233 // "V op' B" is just the RHS.
234 if (V == A || V == CC) {
236 return V == A ? LHS : RHS;
238 // Otherwise return "V op' B" if it simplifies.
239 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) {
249 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
250 /// operations. Returns the simpler value, or null if none was found.
251 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
252 const Query &Q, unsigned MaxRecurse) {
253 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
254 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
256 // Recursion is always used, so bail out at once if we already hit the limit.
260 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
261 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
263 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
264 if (Op0 && Op0->getOpcode() == Opcode) {
265 Value *A = Op0->getOperand(0);
266 Value *B = Op0->getOperand(1);
269 // Does "B op C" simplify?
270 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
271 // It does! Return "A op V" if it simplifies or is already available.
272 // If V equals B then "A op V" is just the LHS.
273 if (V == B) return LHS;
274 // Otherwise return "A op V" if it simplifies.
275 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
282 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
283 if (Op1 && Op1->getOpcode() == Opcode) {
285 Value *B = Op1->getOperand(0);
286 Value *C = Op1->getOperand(1);
288 // Does "A op B" simplify?
289 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
290 // It does! Return "V op C" if it simplifies or is already available.
291 // If V equals B then "V op C" is just the RHS.
292 if (V == B) return RHS;
293 // Otherwise return "V op C" if it simplifies.
294 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
301 // The remaining transforms require commutativity as well as associativity.
302 if (!Instruction::isCommutative(Opcode))
305 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
306 if (Op0 && Op0->getOpcode() == Opcode) {
307 Value *A = Op0->getOperand(0);
308 Value *B = Op0->getOperand(1);
311 // Does "C op A" simplify?
312 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
313 // It does! Return "V op B" if it simplifies or is already available.
314 // If V equals A then "V op B" is just the LHS.
315 if (V == A) return LHS;
316 // Otherwise return "V op B" if it simplifies.
317 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
324 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
325 if (Op1 && Op1->getOpcode() == Opcode) {
327 Value *B = Op1->getOperand(0);
328 Value *C = Op1->getOperand(1);
330 // Does "C op A" simplify?
331 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
332 // It does! Return "B op V" if it simplifies or is already available.
333 // If V equals C then "B op V" is just the RHS.
334 if (V == C) return RHS;
335 // Otherwise return "B op V" if it simplifies.
336 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
346 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
347 /// instruction as an operand, try to simplify the binop by seeing whether
348 /// evaluating it on both branches of the select results in the same value.
349 /// Returns the common value if so, otherwise returns null.
350 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
351 const Query &Q, unsigned MaxRecurse) {
352 // Recursion is always used, so bail out at once if we already hit the limit.
357 if (isa<SelectInst>(LHS)) {
358 SI = cast<SelectInst>(LHS);
360 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
361 SI = cast<SelectInst>(RHS);
364 // Evaluate the BinOp on the true and false branches of the select.
368 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
369 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
371 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
372 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
375 // If they simplified to the same value, then return the common value.
376 // If they both failed to simplify then return null.
380 // If one branch simplified to undef, return the other one.
381 if (TV && isa<UndefValue>(TV))
383 if (FV && isa<UndefValue>(FV))
386 // If applying the operation did not change the true and false select values,
387 // then the result of the binop is the select itself.
388 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
391 // If one branch simplified and the other did not, and the simplified
392 // value is equal to the unsimplified one, return the simplified value.
393 // For example, select (cond, X, X & Z) & Z -> X & Z.
394 if ((FV && !TV) || (TV && !FV)) {
395 // Check that the simplified value has the form "X op Y" where "op" is the
396 // same as the original operation.
397 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
398 if (Simplified && Simplified->getOpcode() == Opcode) {
399 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
400 // We already know that "op" is the same as for the simplified value. See
401 // if the operands match too. If so, return the simplified value.
402 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
403 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
404 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
405 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
406 Simplified->getOperand(1) == UnsimplifiedRHS)
408 if (Simplified->isCommutative() &&
409 Simplified->getOperand(1) == UnsimplifiedLHS &&
410 Simplified->getOperand(0) == UnsimplifiedRHS)
418 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
419 /// try to simplify the comparison by seeing whether both branches of the select
420 /// result in the same value. Returns the common value if so, otherwise returns
422 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
423 Value *RHS, const Query &Q,
424 unsigned MaxRecurse) {
425 // Recursion is always used, so bail out at once if we already hit the limit.
429 // Make sure the select is on the LHS.
430 if (!isa<SelectInst>(LHS)) {
432 Pred = CmpInst::getSwappedPredicate(Pred);
434 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
435 SelectInst *SI = cast<SelectInst>(LHS);
436 Value *Cond = SI->getCondition();
437 Value *TV = SI->getTrueValue();
438 Value *FV = SI->getFalseValue();
440 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
441 // Does "cmp TV, RHS" simplify?
442 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
444 // It not only simplified, it simplified to the select condition. Replace
446 TCmp = getTrue(Cond->getType());
448 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
449 // condition then we can replace it with 'true'. Otherwise give up.
450 if (!isSameCompare(Cond, Pred, TV, RHS))
452 TCmp = getTrue(Cond->getType());
455 // Does "cmp FV, RHS" simplify?
456 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
458 // It not only simplified, it simplified to the select condition. Replace
460 FCmp = getFalse(Cond->getType());
462 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
463 // condition then we can replace it with 'false'. Otherwise give up.
464 if (!isSameCompare(Cond, Pred, FV, RHS))
466 FCmp = getFalse(Cond->getType());
469 // If both sides simplified to the same value, then use it as the result of
470 // the original comparison.
474 // The remaining cases only make sense if the select condition has the same
475 // type as the result of the comparison, so bail out if this is not so.
476 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
478 // If the false value simplified to false, then the result of the compare
479 // is equal to "Cond && TCmp". This also catches the case when the false
480 // value simplified to false and the true value to true, returning "Cond".
481 if (match(FCmp, m_Zero()))
482 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
484 // If the true value simplified to true, then the result of the compare
485 // is equal to "Cond || FCmp".
486 if (match(TCmp, m_One()))
487 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
489 // Finally, if the false value simplified to true and the true value to
490 // false, then the result of the compare is equal to "!Cond".
491 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
493 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
500 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
501 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
502 /// it on the incoming phi values yields the same result for every value. If so
503 /// returns the common value, otherwise returns null.
504 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
505 const Query &Q, unsigned MaxRecurse) {
506 // Recursion is always used, so bail out at once if we already hit the limit.
511 if (isa<PHINode>(LHS)) {
512 PI = cast<PHINode>(LHS);
513 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
514 if (!ValueDominatesPHI(RHS, PI, Q.DT))
517 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
518 PI = cast<PHINode>(RHS);
519 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
520 if (!ValueDominatesPHI(LHS, PI, Q.DT))
524 // Evaluate the BinOp on the incoming phi values.
525 Value *CommonValue = 0;
526 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
527 Value *Incoming = PI->getIncomingValue(i);
528 // If the incoming value is the phi node itself, it can safely be skipped.
529 if (Incoming == PI) continue;
530 Value *V = PI == LHS ?
531 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
532 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
533 // If the operation failed to simplify, or simplified to a different value
534 // to previously, then give up.
535 if (!V || (CommonValue && V != CommonValue))
543 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
544 /// try to simplify the comparison by seeing whether comparing with all of the
545 /// incoming phi values yields the same result every time. If so returns the
546 /// common result, otherwise returns null.
547 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
548 const Query &Q, unsigned MaxRecurse) {
549 // Recursion is always used, so bail out at once if we already hit the limit.
553 // Make sure the phi is on the LHS.
554 if (!isa<PHINode>(LHS)) {
556 Pred = CmpInst::getSwappedPredicate(Pred);
558 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
559 PHINode *PI = cast<PHINode>(LHS);
561 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
562 if (!ValueDominatesPHI(RHS, PI, Q.DT))
565 // Evaluate the BinOp on the incoming phi values.
566 Value *CommonValue = 0;
567 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
568 Value *Incoming = PI->getIncomingValue(i);
569 // If the incoming value is the phi node itself, it can safely be skipped.
570 if (Incoming == PI) continue;
571 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
572 // If the operation failed to simplify, or simplified to a different value
573 // to previously, then give up.
574 if (!V || (CommonValue && V != CommonValue))
582 /// SimplifyAddInst - Given operands for an Add, see if we can
583 /// fold the result. If not, this returns null.
584 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
585 const Query &Q, unsigned MaxRecurse) {
586 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
587 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
588 Constant *Ops[] = { CLHS, CRHS };
589 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops,
593 // Canonicalize the constant to the RHS.
597 // X + undef -> undef
598 if (match(Op1, m_Undef()))
602 if (match(Op1, m_Zero()))
609 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
610 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
613 // X + ~X -> -1 since ~X = -X-1
614 if (match(Op0, m_Not(m_Specific(Op1))) ||
615 match(Op1, m_Not(m_Specific(Op0))))
616 return Constant::getAllOnesValue(Op0->getType());
619 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
620 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
623 // Try some generic simplifications for associative operations.
624 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
628 // Mul distributes over Add. Try some generic simplifications based on this.
629 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
633 // Threading Add over selects and phi nodes is pointless, so don't bother.
634 // Threading over the select in "A + select(cond, B, C)" means evaluating
635 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
636 // only if B and C are equal. If B and C are equal then (since we assume
637 // that operands have already been simplified) "select(cond, B, C)" should
638 // have been simplified to the common value of B and C already. Analysing
639 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
640 // for threading over phi nodes.
645 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
646 const TargetData *TD, const TargetLibraryInfo *TLI,
647 const DominatorTree *DT) {
648 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
652 /// \brief Accumulate the constant integer offset a GEP represents.
654 /// Given a getelementptr instruction/constantexpr, accumulate the constant
655 /// offset from the base pointer into the provided APInt 'Offset'. Returns true
656 /// if the GEP has all-constant indices. Returns false if any non-constant
657 /// index is encountered leaving the 'Offset' in an undefined state. The
658 /// 'Offset' APInt must be the bitwidth of the target's pointer size.
659 static bool accumulateGEPOffset(const TargetData &TD, GEPOperator *GEP,
661 unsigned IntPtrWidth = TD.getPointerSizeInBits();
662 assert(IntPtrWidth == Offset.getBitWidth());
664 gep_type_iterator GTI = gep_type_begin(GEP);
665 for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end(); I != E;
667 ConstantInt *OpC = dyn_cast<ConstantInt>(*I);
668 if (!OpC) return false;
669 if (OpC->isZero()) continue;
671 // Handle a struct index, which adds its field offset to the pointer.
672 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
673 unsigned ElementIdx = OpC->getZExtValue();
674 const StructLayout *SL = TD.getStructLayout(STy);
675 Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx),
680 APInt TypeSize(IntPtrWidth, TD.getTypeAllocSize(GTI.getIndexedType()),
682 Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
687 /// \brief Compute the base pointer and cumulative constant offsets for V.
689 /// This strips all constant offsets off of V, leaving it the base pointer, and
690 /// accumulates the total constant offset applied in the returned constant. It
691 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
692 /// no constant offsets applied.
693 static Constant *stripAndComputeConstantOffsets(const TargetData &TD,
695 if (!V->getType()->isPointerTy())
698 unsigned IntPtrWidth = TD.getPointerSizeInBits();
699 APInt Offset = APInt::getNullValue(IntPtrWidth);
701 // Even though we don't look through PHI nodes, we could be called on an
702 // instruction in an unreachable block, which may be on a cycle.
703 SmallPtrSet<Value *, 4> Visited;
706 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
707 if (!accumulateGEPOffset(TD, GEP, Offset))
709 V = GEP->getPointerOperand();
710 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
711 V = cast<Operator>(V)->getOperand(0);
712 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
713 if (GA->mayBeOverridden())
715 V = GA->getAliasee();
719 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
720 } while (Visited.insert(V));
722 Type *IntPtrTy = TD.getIntPtrType(V->getContext());
723 return ConstantInt::get(IntPtrTy, Offset);
726 /// \brief Compute the constant difference between two pointer values.
727 /// If the difference is not a constant, returns zero.
728 static Constant *computePointerDifference(const TargetData &TD,
729 Value *LHS, Value *RHS) {
730 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
733 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
737 // If LHS and RHS are not related via constant offsets to the same base
738 // value, there is nothing we can do here.
742 // Otherwise, the difference of LHS - RHS can be computed as:
744 // = (LHSOffset + Base) - (RHSOffset + Base)
745 // = LHSOffset - RHSOffset
746 return ConstantExpr::getSub(LHSOffset, RHSOffset);
749 /// SimplifySubInst - Given operands for a Sub, see if we can
750 /// fold the result. If not, this returns null.
751 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
752 const Query &Q, unsigned MaxRecurse) {
753 if (Constant *CLHS = dyn_cast<Constant>(Op0))
754 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
755 Constant *Ops[] = { CLHS, CRHS };
756 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
760 // X - undef -> undef
761 // undef - X -> undef
762 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
763 return UndefValue::get(Op0->getType());
766 if (match(Op1, m_Zero()))
771 return Constant::getNullValue(Op0->getType());
776 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
777 match(Op0, m_Shl(m_Specific(Op1), m_One())))
781 Value *LHSOp, *RHSOp;
782 if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
783 match(Op1, m_PtrToInt(m_Value(RHSOp))))
784 if (Constant *Result = computePointerDifference(*Q.TD, LHSOp, RHSOp))
785 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
787 // trunc(p)-trunc(q) -> trunc(p-q)
788 if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
789 match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
790 if (Constant *Result = computePointerDifference(*Q.TD, LHSOp, RHSOp))
791 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
794 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
795 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
796 Value *Y = 0, *Z = Op1;
797 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
798 // See if "V === Y - Z" simplifies.
799 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
800 // It does! Now see if "X + V" simplifies.
801 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
802 // It does, we successfully reassociated!
806 // See if "V === X - Z" simplifies.
807 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
808 // It does! Now see if "Y + V" simplifies.
809 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
810 // It does, we successfully reassociated!
816 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
817 // For example, X - (X + 1) -> -1
819 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
820 // See if "V === X - Y" simplifies.
821 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
822 // It does! Now see if "V - Z" simplifies.
823 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
824 // It does, we successfully reassociated!
828 // See if "V === X - Z" simplifies.
829 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
830 // It does! Now see if "V - Y" simplifies.
831 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
832 // It does, we successfully reassociated!
838 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
839 // For example, X - (X - Y) -> Y.
841 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
842 // See if "V === Z - X" simplifies.
843 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
844 // It does! Now see if "V + Y" simplifies.
845 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
846 // It does, we successfully reassociated!
851 // Mul distributes over Sub. Try some generic simplifications based on this.
852 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
857 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
858 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
861 // Threading Sub over selects and phi nodes is pointless, so don't bother.
862 // Threading over the select in "A - select(cond, B, C)" means evaluating
863 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
864 // only if B and C are equal. If B and C are equal then (since we assume
865 // that operands have already been simplified) "select(cond, B, C)" should
866 // have been simplified to the common value of B and C already. Analysing
867 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
868 // for threading over phi nodes.
873 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
874 const TargetData *TD, const TargetLibraryInfo *TLI,
875 const DominatorTree *DT) {
876 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
880 /// SimplifyMulInst - Given operands for a Mul, see if we can
881 /// fold the result. If not, this returns null.
882 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
883 unsigned MaxRecurse) {
884 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
885 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
886 Constant *Ops[] = { CLHS, CRHS };
887 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
891 // Canonicalize the constant to the RHS.
896 if (match(Op1, m_Undef()))
897 return Constant::getNullValue(Op0->getType());
900 if (match(Op1, m_Zero()))
904 if (match(Op1, m_One()))
907 // (X / Y) * Y -> X if the division is exact.
909 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
910 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
914 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
915 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
918 // Try some generic simplifications for associative operations.
919 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
923 // Mul distributes over Add. Try some generic simplifications based on this.
924 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
928 // If the operation is with the result of a select instruction, check whether
929 // operating on either branch of the select always yields the same value.
930 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
931 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
935 // If the operation is with the result of a phi instruction, check whether
936 // operating on all incoming values of the phi always yields the same value.
937 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
938 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
945 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
946 const TargetLibraryInfo *TLI,
947 const DominatorTree *DT) {
948 return ::SimplifyMulInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
951 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
952 /// fold the result. If not, this returns null.
953 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
954 const Query &Q, unsigned MaxRecurse) {
955 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
956 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
957 Constant *Ops[] = { C0, C1 };
958 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
962 bool isSigned = Opcode == Instruction::SDiv;
964 // X / undef -> undef
965 if (match(Op1, m_Undef()))
969 if (match(Op0, m_Undef()))
970 return Constant::getNullValue(Op0->getType());
972 // 0 / X -> 0, we don't need to preserve faults!
973 if (match(Op0, m_Zero()))
977 if (match(Op1, m_One()))
980 if (Op0->getType()->isIntegerTy(1))
981 // It can't be division by zero, hence it must be division by one.
986 return ConstantInt::get(Op0->getType(), 1);
988 // (X * Y) / Y -> X if the multiplication does not overflow.
989 Value *X = 0, *Y = 0;
990 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
991 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
992 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
993 // If the Mul knows it does not overflow, then we are good to go.
994 if ((isSigned && Mul->hasNoSignedWrap()) ||
995 (!isSigned && Mul->hasNoUnsignedWrap()))
997 // If X has the form X = A / Y then X * Y cannot overflow.
998 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
999 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1003 // (X rem Y) / Y -> 0
1004 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1005 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1006 return Constant::getNullValue(Op0->getType());
1008 // If the operation is with the result of a select instruction, check whether
1009 // operating on either branch of the select always yields the same value.
1010 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1011 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1014 // If the operation is with the result of a phi instruction, check whether
1015 // operating on all incoming values of the phi always yields the same value.
1016 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1017 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1023 /// SimplifySDivInst - Given operands for an SDiv, see if we can
1024 /// fold the result. If not, this returns null.
1025 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
1026 unsigned MaxRecurse) {
1027 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
1033 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1034 const TargetLibraryInfo *TLI,
1035 const DominatorTree *DT) {
1036 return ::SimplifySDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1039 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
1040 /// fold the result. If not, this returns null.
1041 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
1042 unsigned MaxRecurse) {
1043 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
1049 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1050 const TargetLibraryInfo *TLI,
1051 const DominatorTree *DT) {
1052 return ::SimplifyUDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1055 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q,
1057 // undef / X -> undef (the undef could be a snan).
1058 if (match(Op0, m_Undef()))
1061 // X / undef -> undef
1062 if (match(Op1, m_Undef()))
1068 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1069 const TargetLibraryInfo *TLI,
1070 const DominatorTree *DT) {
1071 return ::SimplifyFDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1074 /// SimplifyRem - Given operands for an SRem or URem, see if we can
1075 /// fold the result. If not, this returns null.
1076 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1077 const Query &Q, unsigned MaxRecurse) {
1078 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1079 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1080 Constant *Ops[] = { C0, C1 };
1081 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
1085 // X % undef -> undef
1086 if (match(Op1, m_Undef()))
1090 if (match(Op0, m_Undef()))
1091 return Constant::getNullValue(Op0->getType());
1093 // 0 % X -> 0, we don't need to preserve faults!
1094 if (match(Op0, m_Zero()))
1097 // X % 0 -> undef, we don't need to preserve faults!
1098 if (match(Op1, m_Zero()))
1099 return UndefValue::get(Op0->getType());
1102 if (match(Op1, m_One()))
1103 return Constant::getNullValue(Op0->getType());
1105 if (Op0->getType()->isIntegerTy(1))
1106 // It can't be remainder by zero, hence it must be remainder by one.
1107 return Constant::getNullValue(Op0->getType());
1111 return Constant::getNullValue(Op0->getType());
1113 // If the operation is with the result of a select instruction, check whether
1114 // operating on either branch of the select always yields the same value.
1115 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1116 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1119 // If the operation is with the result of a phi instruction, check whether
1120 // operating on all incoming values of the phi always yields the same value.
1121 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1122 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1128 /// SimplifySRemInst - Given operands for an SRem, see if we can
1129 /// fold the result. If not, this returns null.
1130 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
1131 unsigned MaxRecurse) {
1132 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
1138 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1139 const TargetLibraryInfo *TLI,
1140 const DominatorTree *DT) {
1141 return ::SimplifySRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1144 /// SimplifyURemInst - Given operands for a URem, see if we can
1145 /// fold the result. If not, this returns null.
1146 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
1147 unsigned MaxRecurse) {
1148 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
1154 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1155 const TargetLibraryInfo *TLI,
1156 const DominatorTree *DT) {
1157 return ::SimplifyURemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1160 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &,
1162 // undef % X -> undef (the undef could be a snan).
1163 if (match(Op0, m_Undef()))
1166 // X % undef -> undef
1167 if (match(Op1, m_Undef()))
1173 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1174 const TargetLibraryInfo *TLI,
1175 const DominatorTree *DT) {
1176 return ::SimplifyFRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1179 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1180 /// fold the result. If not, this returns null.
1181 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1182 const Query &Q, unsigned MaxRecurse) {
1183 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1184 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1185 Constant *Ops[] = { C0, C1 };
1186 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
1190 // 0 shift by X -> 0
1191 if (match(Op0, m_Zero()))
1194 // X shift by 0 -> X
1195 if (match(Op1, m_Zero()))
1198 // X shift by undef -> undef because it may shift by the bitwidth.
1199 if (match(Op1, m_Undef()))
1202 // Shifting by the bitwidth or more is undefined.
1203 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
1204 if (CI->getValue().getLimitedValue() >=
1205 Op0->getType()->getScalarSizeInBits())
1206 return UndefValue::get(Op0->getType());
1208 // If the operation is with the result of a select instruction, check whether
1209 // operating on either branch of the select always yields the same value.
1210 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1211 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1214 // If the operation is with the result of a phi instruction, check whether
1215 // operating on all incoming values of the phi always yields the same value.
1216 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1217 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1223 /// SimplifyShlInst - Given operands for an Shl, see if we can
1224 /// fold the result. If not, this returns null.
1225 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1226 const Query &Q, unsigned MaxRecurse) {
1227 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1231 if (match(Op0, m_Undef()))
1232 return Constant::getNullValue(Op0->getType());
1234 // (X >> A) << A -> X
1236 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1241 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1242 const TargetData *TD, const TargetLibraryInfo *TLI,
1243 const DominatorTree *DT) {
1244 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
1248 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1249 /// fold the result. If not, this returns null.
1250 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1251 const Query &Q, unsigned MaxRecurse) {
1252 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse))
1256 if (match(Op0, m_Undef()))
1257 return Constant::getNullValue(Op0->getType());
1259 // (X << A) >> A -> X
1261 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1262 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
1268 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1269 const TargetData *TD,
1270 const TargetLibraryInfo *TLI,
1271 const DominatorTree *DT) {
1272 return ::SimplifyLShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
1276 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1277 /// fold the result. If not, this returns null.
1278 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1279 const Query &Q, unsigned MaxRecurse) {
1280 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse))
1283 // all ones >>a X -> all ones
1284 if (match(Op0, m_AllOnes()))
1287 // undef >>a X -> all ones
1288 if (match(Op0, m_Undef()))
1289 return Constant::getAllOnesValue(Op0->getType());
1291 // (X << A) >> A -> X
1293 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1294 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
1300 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1301 const TargetData *TD,
1302 const TargetLibraryInfo *TLI,
1303 const DominatorTree *DT) {
1304 return ::SimplifyAShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
1308 /// SimplifyAndInst - Given operands for an And, see if we can
1309 /// fold the result. If not, this returns null.
1310 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
1311 unsigned MaxRecurse) {
1312 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1313 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1314 Constant *Ops[] = { CLHS, CRHS };
1315 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1319 // Canonicalize the constant to the RHS.
1320 std::swap(Op0, Op1);
1324 if (match(Op1, m_Undef()))
1325 return Constant::getNullValue(Op0->getType());
1332 if (match(Op1, m_Zero()))
1336 if (match(Op1, m_AllOnes()))
1339 // A & ~A = ~A & A = 0
1340 if (match(Op0, m_Not(m_Specific(Op1))) ||
1341 match(Op1, m_Not(m_Specific(Op0))))
1342 return Constant::getNullValue(Op0->getType());
1345 Value *A = 0, *B = 0;
1346 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1347 (A == Op1 || B == Op1))
1351 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1352 (A == Op0 || B == Op0))
1355 // A & (-A) = A if A is a power of two or zero.
1356 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1357 match(Op1, m_Neg(m_Specific(Op0)))) {
1358 if (isPowerOfTwo(Op0, Q.TD, /*OrZero*/true))
1360 if (isPowerOfTwo(Op1, Q.TD, /*OrZero*/true))
1364 // Try some generic simplifications for associative operations.
1365 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1369 // And distributes over Or. Try some generic simplifications based on this.
1370 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1374 // And distributes over Xor. Try some generic simplifications based on this.
1375 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1379 // Or distributes over And. Try some generic simplifications based on this.
1380 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1384 // If the operation is with the result of a select instruction, check whether
1385 // operating on either branch of the select always yields the same value.
1386 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1387 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1391 // If the operation is with the result of a phi instruction, check whether
1392 // operating on all incoming values of the phi always yields the same value.
1393 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1394 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1401 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1402 const TargetLibraryInfo *TLI,
1403 const DominatorTree *DT) {
1404 return ::SimplifyAndInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1407 /// SimplifyOrInst - Given operands for an Or, see if we can
1408 /// fold the result. If not, this returns null.
1409 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
1410 unsigned MaxRecurse) {
1411 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1412 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1413 Constant *Ops[] = { CLHS, CRHS };
1414 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1418 // Canonicalize the constant to the RHS.
1419 std::swap(Op0, Op1);
1423 if (match(Op1, m_Undef()))
1424 return Constant::getAllOnesValue(Op0->getType());
1431 if (match(Op1, m_Zero()))
1435 if (match(Op1, m_AllOnes()))
1438 // A | ~A = ~A | A = -1
1439 if (match(Op0, m_Not(m_Specific(Op1))) ||
1440 match(Op1, m_Not(m_Specific(Op0))))
1441 return Constant::getAllOnesValue(Op0->getType());
1444 Value *A = 0, *B = 0;
1445 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1446 (A == Op1 || B == Op1))
1450 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1451 (A == Op0 || B == Op0))
1454 // ~(A & ?) | A = -1
1455 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1456 (A == Op1 || B == Op1))
1457 return Constant::getAllOnesValue(Op1->getType());
1459 // A | ~(A & ?) = -1
1460 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1461 (A == Op0 || B == Op0))
1462 return Constant::getAllOnesValue(Op0->getType());
1464 // Try some generic simplifications for associative operations.
1465 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1469 // Or distributes over And. Try some generic simplifications based on this.
1470 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1474 // And distributes over Or. Try some generic simplifications based on this.
1475 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1479 // If the operation is with the result of a select instruction, check whether
1480 // operating on either branch of the select always yields the same value.
1481 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1482 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1486 // If the operation is with the result of a phi instruction, check whether
1487 // operating on all incoming values of the phi always yields the same value.
1488 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1489 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1495 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1496 const TargetLibraryInfo *TLI,
1497 const DominatorTree *DT) {
1498 return ::SimplifyOrInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1501 /// SimplifyXorInst - Given operands for a Xor, see if we can
1502 /// fold the result. If not, this returns null.
1503 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q,
1504 unsigned MaxRecurse) {
1505 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1506 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1507 Constant *Ops[] = { CLHS, CRHS };
1508 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1512 // Canonicalize the constant to the RHS.
1513 std::swap(Op0, Op1);
1516 // A ^ undef -> undef
1517 if (match(Op1, m_Undef()))
1521 if (match(Op1, m_Zero()))
1526 return Constant::getNullValue(Op0->getType());
1528 // A ^ ~A = ~A ^ A = -1
1529 if (match(Op0, m_Not(m_Specific(Op1))) ||
1530 match(Op1, m_Not(m_Specific(Op0))))
1531 return Constant::getAllOnesValue(Op0->getType());
1533 // Try some generic simplifications for associative operations.
1534 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1538 // And distributes over Xor. Try some generic simplifications based on this.
1539 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1543 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1544 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1545 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1546 // only if B and C are equal. If B and C are equal then (since we assume
1547 // that operands have already been simplified) "select(cond, B, C)" should
1548 // have been simplified to the common value of B and C already. Analysing
1549 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1550 // for threading over phi nodes.
1555 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1556 const TargetLibraryInfo *TLI,
1557 const DominatorTree *DT) {
1558 return ::SimplifyXorInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1561 static Type *GetCompareTy(Value *Op) {
1562 return CmpInst::makeCmpResultType(Op->getType());
1565 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1566 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1567 /// otherwise return null. Helper function for analyzing max/min idioms.
1568 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1569 Value *LHS, Value *RHS) {
1570 SelectInst *SI = dyn_cast<SelectInst>(V);
1573 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1576 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1577 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1579 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1580 LHS == CmpRHS && RHS == CmpLHS)
1586 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1587 /// fold the result. If not, this returns null.
1588 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1589 const Query &Q, unsigned MaxRecurse) {
1590 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1591 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1593 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1594 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1595 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI);
1597 // If we have a constant, make sure it is on the RHS.
1598 std::swap(LHS, RHS);
1599 Pred = CmpInst::getSwappedPredicate(Pred);
1602 Type *ITy = GetCompareTy(LHS); // The return type.
1603 Type *OpTy = LHS->getType(); // The operand type.
1605 // icmp X, X -> true/false
1606 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1607 // because X could be 0.
1608 if (LHS == RHS || isa<UndefValue>(RHS))
1609 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1611 // Special case logic when the operands have i1 type.
1612 if (OpTy->getScalarType()->isIntegerTy(1)) {
1615 case ICmpInst::ICMP_EQ:
1617 if (match(RHS, m_One()))
1620 case ICmpInst::ICMP_NE:
1622 if (match(RHS, m_Zero()))
1625 case ICmpInst::ICMP_UGT:
1627 if (match(RHS, m_Zero()))
1630 case ICmpInst::ICMP_UGE:
1632 if (match(RHS, m_One()))
1635 case ICmpInst::ICMP_SLT:
1637 if (match(RHS, m_Zero()))
1640 case ICmpInst::ICMP_SLE:
1642 if (match(RHS, m_One()))
1648 // icmp <object*>, <object*/null> - Different identified objects have
1649 // different addresses (unless null), and what's more the address of an
1650 // identified local is never equal to another argument (again, barring null).
1651 // Note that generalizing to the case where LHS is a global variable address
1652 // or null is pointless, since if both LHS and RHS are constants then we
1653 // already constant folded the compare, and if only one of them is then we
1654 // moved it to RHS already.
1655 Value *LHSPtr = LHS->stripPointerCasts();
1656 Value *RHSPtr = RHS->stripPointerCasts();
1657 if (LHSPtr == RHSPtr)
1658 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1660 // Be more aggressive about stripping pointer adjustments when checking a
1661 // comparison of an alloca address to another object. We can rip off all
1662 // inbounds GEP operations, even if they are variable.
1663 LHSPtr = LHSPtr->stripInBoundsOffsets();
1664 if (llvm::isIdentifiedObject(LHSPtr)) {
1665 RHSPtr = RHSPtr->stripInBoundsOffsets();
1666 if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) {
1667 // If both sides are different identified objects, they aren't equal
1668 // unless they're null.
1669 if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) &&
1670 Pred == CmpInst::ICMP_EQ)
1671 return ConstantInt::get(ITy, false);
1673 // A local identified object (alloca or noalias call) can't equal any
1674 // incoming argument, unless they're both null.
1675 if (isa<Instruction>(LHSPtr) && isa<Argument>(RHSPtr) &&
1676 Pred == CmpInst::ICMP_EQ)
1677 return ConstantInt::get(ITy, false);
1680 // Assume that the constant null is on the right.
1681 if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) {
1682 if (Pred == CmpInst::ICMP_EQ)
1683 return ConstantInt::get(ITy, false);
1684 else if (Pred == CmpInst::ICMP_NE)
1685 return ConstantInt::get(ITy, true);
1687 } else if (isa<Argument>(LHSPtr)) {
1688 RHSPtr = RHSPtr->stripInBoundsOffsets();
1689 // An alloca can't be equal to an argument.
1690 if (isa<AllocaInst>(RHSPtr)) {
1691 if (Pred == CmpInst::ICMP_EQ)
1692 return ConstantInt::get(ITy, false);
1693 else if (Pred == CmpInst::ICMP_NE)
1694 return ConstantInt::get(ITy, true);
1698 // If we are comparing with zero then try hard since this is a common case.
1699 if (match(RHS, m_Zero())) {
1700 bool LHSKnownNonNegative, LHSKnownNegative;
1702 default: llvm_unreachable("Unknown ICmp predicate!");
1703 case ICmpInst::ICMP_ULT:
1704 return getFalse(ITy);
1705 case ICmpInst::ICMP_UGE:
1706 return getTrue(ITy);
1707 case ICmpInst::ICMP_EQ:
1708 case ICmpInst::ICMP_ULE:
1709 if (isKnownNonZero(LHS, Q.TD))
1710 return getFalse(ITy);
1712 case ICmpInst::ICMP_NE:
1713 case ICmpInst::ICMP_UGT:
1714 if (isKnownNonZero(LHS, Q.TD))
1715 return getTrue(ITy);
1717 case ICmpInst::ICMP_SLT:
1718 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1719 if (LHSKnownNegative)
1720 return getTrue(ITy);
1721 if (LHSKnownNonNegative)
1722 return getFalse(ITy);
1724 case ICmpInst::ICMP_SLE:
1725 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1726 if (LHSKnownNegative)
1727 return getTrue(ITy);
1728 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
1729 return getFalse(ITy);
1731 case ICmpInst::ICMP_SGE:
1732 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1733 if (LHSKnownNegative)
1734 return getFalse(ITy);
1735 if (LHSKnownNonNegative)
1736 return getTrue(ITy);
1738 case ICmpInst::ICMP_SGT:
1739 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1740 if (LHSKnownNegative)
1741 return getFalse(ITy);
1742 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
1743 return getTrue(ITy);
1748 // See if we are doing a comparison with a constant integer.
1749 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1750 // Rule out tautological comparisons (eg., ult 0 or uge 0).
1751 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
1752 if (RHS_CR.isEmptySet())
1753 return ConstantInt::getFalse(CI->getContext());
1754 if (RHS_CR.isFullSet())
1755 return ConstantInt::getTrue(CI->getContext());
1757 // Many binary operators with constant RHS have easy to compute constant
1758 // range. Use them to check whether the comparison is a tautology.
1759 uint32_t Width = CI->getBitWidth();
1760 APInt Lower = APInt(Width, 0);
1761 APInt Upper = APInt(Width, 0);
1763 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
1764 // 'urem x, CI2' produces [0, CI2).
1765 Upper = CI2->getValue();
1766 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
1767 // 'srem x, CI2' produces (-|CI2|, |CI2|).
1768 Upper = CI2->getValue().abs();
1769 Lower = (-Upper) + 1;
1770 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
1771 // 'udiv CI2, x' produces [0, CI2].
1772 Upper = CI2->getValue() + 1;
1773 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
1774 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
1775 APInt NegOne = APInt::getAllOnesValue(Width);
1777 Upper = NegOne.udiv(CI2->getValue()) + 1;
1778 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
1779 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
1780 APInt IntMin = APInt::getSignedMinValue(Width);
1781 APInt IntMax = APInt::getSignedMaxValue(Width);
1782 APInt Val = CI2->getValue().abs();
1783 if (!Val.isMinValue()) {
1784 Lower = IntMin.sdiv(Val);
1785 Upper = IntMax.sdiv(Val) + 1;
1787 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
1788 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
1789 APInt NegOne = APInt::getAllOnesValue(Width);
1790 if (CI2->getValue().ult(Width))
1791 Upper = NegOne.lshr(CI2->getValue()) + 1;
1792 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
1793 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
1794 APInt IntMin = APInt::getSignedMinValue(Width);
1795 APInt IntMax = APInt::getSignedMaxValue(Width);
1796 if (CI2->getValue().ult(Width)) {
1797 Lower = IntMin.ashr(CI2->getValue());
1798 Upper = IntMax.ashr(CI2->getValue()) + 1;
1800 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
1801 // 'or x, CI2' produces [CI2, UINT_MAX].
1802 Lower = CI2->getValue();
1803 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
1804 // 'and x, CI2' produces [0, CI2].
1805 Upper = CI2->getValue() + 1;
1807 if (Lower != Upper) {
1808 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
1809 if (RHS_CR.contains(LHS_CR))
1810 return ConstantInt::getTrue(RHS->getContext());
1811 if (RHS_CR.inverse().contains(LHS_CR))
1812 return ConstantInt::getFalse(RHS->getContext());
1816 // Compare of cast, for example (zext X) != 0 -> X != 0
1817 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1818 Instruction *LI = cast<CastInst>(LHS);
1819 Value *SrcOp = LI->getOperand(0);
1820 Type *SrcTy = SrcOp->getType();
1821 Type *DstTy = LI->getType();
1823 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1824 // if the integer type is the same size as the pointer type.
1825 if (MaxRecurse && Q.TD && isa<PtrToIntInst>(LI) &&
1826 Q.TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1827 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1828 // Transfer the cast to the constant.
1829 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1830 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1833 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1834 if (RI->getOperand(0)->getType() == SrcTy)
1835 // Compare without the cast.
1836 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1842 if (isa<ZExtInst>(LHS)) {
1843 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1845 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1846 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1847 // Compare X and Y. Note that signed predicates become unsigned.
1848 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1849 SrcOp, RI->getOperand(0), Q,
1853 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1854 // too. If not, then try to deduce the result of the comparison.
1855 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1856 // Compute the constant that would happen if we truncated to SrcTy then
1857 // reextended to DstTy.
1858 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1859 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1861 // If the re-extended constant didn't change then this is effectively
1862 // also a case of comparing two zero-extended values.
1863 if (RExt == CI && MaxRecurse)
1864 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1865 SrcOp, Trunc, Q, MaxRecurse-1))
1868 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1869 // there. Use this to work out the result of the comparison.
1872 default: llvm_unreachable("Unknown ICmp predicate!");
1874 case ICmpInst::ICMP_EQ:
1875 case ICmpInst::ICMP_UGT:
1876 case ICmpInst::ICMP_UGE:
1877 return ConstantInt::getFalse(CI->getContext());
1879 case ICmpInst::ICMP_NE:
1880 case ICmpInst::ICMP_ULT:
1881 case ICmpInst::ICMP_ULE:
1882 return ConstantInt::getTrue(CI->getContext());
1884 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1885 // is non-negative then LHS <s RHS.
1886 case ICmpInst::ICMP_SGT:
1887 case ICmpInst::ICMP_SGE:
1888 return CI->getValue().isNegative() ?
1889 ConstantInt::getTrue(CI->getContext()) :
1890 ConstantInt::getFalse(CI->getContext());
1892 case ICmpInst::ICMP_SLT:
1893 case ICmpInst::ICMP_SLE:
1894 return CI->getValue().isNegative() ?
1895 ConstantInt::getFalse(CI->getContext()) :
1896 ConstantInt::getTrue(CI->getContext());
1902 if (isa<SExtInst>(LHS)) {
1903 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1905 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1906 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1907 // Compare X and Y. Note that the predicate does not change.
1908 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1912 // Turn icmp (sext 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::SExt, Trunc, DstTy);
1920 // If the re-extended constant didn't change then this is effectively
1921 // also a case of comparing two sign-extended values.
1922 if (RExt == CI && MaxRecurse)
1923 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
1926 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1927 // bits there. Use this to work out the result of the comparison.
1930 default: llvm_unreachable("Unknown ICmp predicate!");
1931 case ICmpInst::ICMP_EQ:
1932 return ConstantInt::getFalse(CI->getContext());
1933 case ICmpInst::ICMP_NE:
1934 return ConstantInt::getTrue(CI->getContext());
1936 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1938 case ICmpInst::ICMP_SGT:
1939 case ICmpInst::ICMP_SGE:
1940 return CI->getValue().isNegative() ?
1941 ConstantInt::getTrue(CI->getContext()) :
1942 ConstantInt::getFalse(CI->getContext());
1943 case ICmpInst::ICMP_SLT:
1944 case ICmpInst::ICMP_SLE:
1945 return CI->getValue().isNegative() ?
1946 ConstantInt::getFalse(CI->getContext()) :
1947 ConstantInt::getTrue(CI->getContext());
1949 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
1951 case ICmpInst::ICMP_UGT:
1952 case ICmpInst::ICMP_UGE:
1953 // Comparison is true iff the LHS <s 0.
1955 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
1956 Constant::getNullValue(SrcTy),
1960 case ICmpInst::ICMP_ULT:
1961 case ICmpInst::ICMP_ULE:
1962 // Comparison is true iff the LHS >=s 0.
1964 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
1965 Constant::getNullValue(SrcTy),
1975 // Special logic for binary operators.
1976 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
1977 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
1978 if (MaxRecurse && (LBO || RBO)) {
1979 // Analyze the case when either LHS or RHS is an add instruction.
1980 Value *A = 0, *B = 0, *C = 0, *D = 0;
1981 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
1982 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
1983 if (LBO && LBO->getOpcode() == Instruction::Add) {
1984 A = LBO->getOperand(0); B = LBO->getOperand(1);
1985 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
1986 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
1987 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
1989 if (RBO && RBO->getOpcode() == Instruction::Add) {
1990 C = RBO->getOperand(0); D = RBO->getOperand(1);
1991 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
1992 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
1993 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
1996 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
1997 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
1998 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
1999 Constant::getNullValue(RHS->getType()),
2003 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2004 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2005 if (Value *V = SimplifyICmpInst(Pred,
2006 Constant::getNullValue(LHS->getType()),
2007 C == LHS ? D : C, Q, MaxRecurse-1))
2010 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2011 if (A && C && (A == C || A == D || B == C || B == D) &&
2012 NoLHSWrapProblem && NoRHSWrapProblem) {
2013 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2014 Value *Y = (A == C || A == D) ? B : A;
2015 Value *Z = (C == A || C == B) ? D : C;
2016 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
2021 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2022 bool KnownNonNegative, KnownNegative;
2026 case ICmpInst::ICMP_SGT:
2027 case ICmpInst::ICMP_SGE:
2028 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
2029 if (!KnownNonNegative)
2032 case ICmpInst::ICMP_EQ:
2033 case ICmpInst::ICMP_UGT:
2034 case ICmpInst::ICMP_UGE:
2035 return getFalse(ITy);
2036 case ICmpInst::ICMP_SLT:
2037 case ICmpInst::ICMP_SLE:
2038 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
2039 if (!KnownNonNegative)
2042 case ICmpInst::ICMP_NE:
2043 case ICmpInst::ICMP_ULT:
2044 case ICmpInst::ICMP_ULE:
2045 return getTrue(ITy);
2048 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2049 bool KnownNonNegative, KnownNegative;
2053 case ICmpInst::ICMP_SGT:
2054 case ICmpInst::ICMP_SGE:
2055 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
2056 if (!KnownNonNegative)
2059 case ICmpInst::ICMP_NE:
2060 case ICmpInst::ICMP_UGT:
2061 case ICmpInst::ICMP_UGE:
2062 return getTrue(ITy);
2063 case ICmpInst::ICMP_SLT:
2064 case ICmpInst::ICMP_SLE:
2065 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
2066 if (!KnownNonNegative)
2069 case ICmpInst::ICMP_EQ:
2070 case ICmpInst::ICMP_ULT:
2071 case ICmpInst::ICMP_ULE:
2072 return getFalse(ITy);
2077 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2078 // icmp pred (X /u Y), X
2079 if (Pred == ICmpInst::ICMP_UGT)
2080 return getFalse(ITy);
2081 if (Pred == ICmpInst::ICMP_ULE)
2082 return getTrue(ITy);
2085 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2086 LBO->getOperand(1) == RBO->getOperand(1)) {
2087 switch (LBO->getOpcode()) {
2089 case Instruction::UDiv:
2090 case Instruction::LShr:
2091 if (ICmpInst::isSigned(Pred))
2094 case Instruction::SDiv:
2095 case Instruction::AShr:
2096 if (!LBO->isExact() || !RBO->isExact())
2098 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2099 RBO->getOperand(0), Q, MaxRecurse-1))
2102 case Instruction::Shl: {
2103 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2104 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2107 if (!NSW && ICmpInst::isSigned(Pred))
2109 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2110 RBO->getOperand(0), Q, MaxRecurse-1))
2117 // Simplify comparisons involving max/min.
2119 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2120 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2122 // Signed variants on "max(a,b)>=a -> true".
2123 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2124 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2125 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2126 // We analyze this as smax(A, B) pred A.
2128 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2129 (A == LHS || B == LHS)) {
2130 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2131 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2132 // We analyze this as smax(A, B) swapped-pred A.
2133 P = CmpInst::getSwappedPredicate(Pred);
2134 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2135 (A == RHS || B == RHS)) {
2136 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2137 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2138 // We analyze this as smax(-A, -B) swapped-pred -A.
2139 // Note that we do not need to actually form -A or -B thanks to EqP.
2140 P = CmpInst::getSwappedPredicate(Pred);
2141 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2142 (A == LHS || B == LHS)) {
2143 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2144 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2145 // We analyze this as smax(-A, -B) pred -A.
2146 // Note that we do not need to actually form -A or -B thanks to EqP.
2149 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2150 // Cases correspond to "max(A, B) p A".
2154 case CmpInst::ICMP_EQ:
2155 case CmpInst::ICMP_SLE:
2156 // Equivalent to "A EqP B". This may be the same as the condition tested
2157 // in the max/min; if so, we can just return that.
2158 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2160 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2162 // Otherwise, see if "A EqP B" simplifies.
2164 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2167 case CmpInst::ICMP_NE:
2168 case CmpInst::ICMP_SGT: {
2169 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2170 // Equivalent to "A InvEqP B". This may be the same as the condition
2171 // tested in the max/min; if so, we can just return that.
2172 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2174 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2176 // Otherwise, see if "A InvEqP B" simplifies.
2178 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2182 case CmpInst::ICMP_SGE:
2184 return getTrue(ITy);
2185 case CmpInst::ICMP_SLT:
2187 return getFalse(ITy);
2191 // Unsigned variants on "max(a,b)>=a -> true".
2192 P = CmpInst::BAD_ICMP_PREDICATE;
2193 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2194 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2195 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2196 // We analyze this as umax(A, B) pred A.
2198 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2199 (A == LHS || B == LHS)) {
2200 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2201 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2202 // We analyze this as umax(A, B) swapped-pred A.
2203 P = CmpInst::getSwappedPredicate(Pred);
2204 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2205 (A == RHS || B == RHS)) {
2206 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2207 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2208 // We analyze this as umax(-A, -B) swapped-pred -A.
2209 // Note that we do not need to actually form -A or -B thanks to EqP.
2210 P = CmpInst::getSwappedPredicate(Pred);
2211 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2212 (A == LHS || B == LHS)) {
2213 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2214 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2215 // We analyze this as umax(-A, -B) pred -A.
2216 // Note that we do not need to actually form -A or -B thanks to EqP.
2219 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2220 // Cases correspond to "max(A, B) p A".
2224 case CmpInst::ICMP_EQ:
2225 case CmpInst::ICMP_ULE:
2226 // Equivalent to "A EqP B". This may be the same as the condition tested
2227 // in the max/min; if so, we can just return that.
2228 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2230 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2232 // Otherwise, see if "A EqP B" simplifies.
2234 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2237 case CmpInst::ICMP_NE:
2238 case CmpInst::ICMP_UGT: {
2239 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2240 // Equivalent to "A InvEqP B". This may be the same as the condition
2241 // tested in the max/min; if so, we can just return that.
2242 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2244 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2246 // Otherwise, see if "A InvEqP B" simplifies.
2248 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2252 case CmpInst::ICMP_UGE:
2254 return getTrue(ITy);
2255 case CmpInst::ICMP_ULT:
2257 return getFalse(ITy);
2261 // Variants on "max(x,y) >= min(x,z)".
2263 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2264 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2265 (A == C || A == D || B == C || B == D)) {
2266 // max(x, ?) pred min(x, ?).
2267 if (Pred == CmpInst::ICMP_SGE)
2269 return getTrue(ITy);
2270 if (Pred == CmpInst::ICMP_SLT)
2272 return getFalse(ITy);
2273 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2274 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2275 (A == C || A == D || B == C || B == D)) {
2276 // min(x, ?) pred max(x, ?).
2277 if (Pred == CmpInst::ICMP_SLE)
2279 return getTrue(ITy);
2280 if (Pred == CmpInst::ICMP_SGT)
2282 return getFalse(ITy);
2283 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2284 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2285 (A == C || A == D || B == C || B == D)) {
2286 // max(x, ?) pred min(x, ?).
2287 if (Pred == CmpInst::ICMP_UGE)
2289 return getTrue(ITy);
2290 if (Pred == CmpInst::ICMP_ULT)
2292 return getFalse(ITy);
2293 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2294 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2295 (A == C || A == D || B == C || B == D)) {
2296 // min(x, ?) pred max(x, ?).
2297 if (Pred == CmpInst::ICMP_ULE)
2299 return getTrue(ITy);
2300 if (Pred == CmpInst::ICMP_UGT)
2302 return getFalse(ITy);
2305 // Simplify comparisons of GEPs.
2306 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
2307 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
2308 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
2309 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
2310 (ICmpInst::isEquality(Pred) ||
2311 (GLHS->isInBounds() && GRHS->isInBounds() &&
2312 Pred == ICmpInst::getSignedPredicate(Pred)))) {
2313 // The bases are equal and the indices are constant. Build a constant
2314 // expression GEP with the same indices and a null base pointer to see
2315 // what constant folding can make out of it.
2316 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
2317 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
2318 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS);
2320 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
2321 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS);
2322 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
2327 // If the comparison is with the result of a select instruction, check whether
2328 // comparing with either branch of the select always yields the same value.
2329 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2330 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2333 // If the comparison is with the result of a phi instruction, check whether
2334 // doing the compare with each incoming phi value yields a common result.
2335 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2336 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2342 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2343 const TargetData *TD,
2344 const TargetLibraryInfo *TLI,
2345 const DominatorTree *DT) {
2346 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2350 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
2351 /// fold the result. If not, this returns null.
2352 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2353 const Query &Q, unsigned MaxRecurse) {
2354 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2355 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
2357 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2358 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2359 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI);
2361 // If we have a constant, make sure it is on the RHS.
2362 std::swap(LHS, RHS);
2363 Pred = CmpInst::getSwappedPredicate(Pred);
2366 // Fold trivial predicates.
2367 if (Pred == FCmpInst::FCMP_FALSE)
2368 return ConstantInt::get(GetCompareTy(LHS), 0);
2369 if (Pred == FCmpInst::FCMP_TRUE)
2370 return ConstantInt::get(GetCompareTy(LHS), 1);
2372 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
2373 return UndefValue::get(GetCompareTy(LHS));
2375 // fcmp x,x -> true/false. Not all compares are foldable.
2377 if (CmpInst::isTrueWhenEqual(Pred))
2378 return ConstantInt::get(GetCompareTy(LHS), 1);
2379 if (CmpInst::isFalseWhenEqual(Pred))
2380 return ConstantInt::get(GetCompareTy(LHS), 0);
2383 // Handle fcmp with constant RHS
2384 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2385 // If the constant is a nan, see if we can fold the comparison based on it.
2386 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2387 if (CFP->getValueAPF().isNaN()) {
2388 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
2389 return ConstantInt::getFalse(CFP->getContext());
2390 assert(FCmpInst::isUnordered(Pred) &&
2391 "Comparison must be either ordered or unordered!");
2392 // True if unordered.
2393 return ConstantInt::getTrue(CFP->getContext());
2395 // Check whether the constant is an infinity.
2396 if (CFP->getValueAPF().isInfinity()) {
2397 if (CFP->getValueAPF().isNegative()) {
2399 case FCmpInst::FCMP_OLT:
2400 // No value is ordered and less than negative infinity.
2401 return ConstantInt::getFalse(CFP->getContext());
2402 case FCmpInst::FCMP_UGE:
2403 // All values are unordered with or at least negative infinity.
2404 return ConstantInt::getTrue(CFP->getContext());
2410 case FCmpInst::FCMP_OGT:
2411 // No value is ordered and greater than infinity.
2412 return ConstantInt::getFalse(CFP->getContext());
2413 case FCmpInst::FCMP_ULE:
2414 // All values are unordered with and at most infinity.
2415 return ConstantInt::getTrue(CFP->getContext());
2424 // If the comparison is with the result of a select instruction, check whether
2425 // comparing with either branch of the select always yields the same value.
2426 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2427 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2430 // If the comparison is with the result of a phi instruction, check whether
2431 // doing the compare with each incoming phi value yields a common result.
2432 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2433 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2439 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2440 const TargetData *TD,
2441 const TargetLibraryInfo *TLI,
2442 const DominatorTree *DT) {
2443 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2447 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
2448 /// the result. If not, this returns null.
2449 static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
2450 Value *FalseVal, const Query &Q,
2451 unsigned MaxRecurse) {
2452 // select true, X, Y -> X
2453 // select false, X, Y -> Y
2454 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
2455 return CB->getZExtValue() ? TrueVal : FalseVal;
2457 // select C, X, X -> X
2458 if (TrueVal == FalseVal)
2461 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
2462 if (isa<Constant>(TrueVal))
2466 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
2468 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
2474 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
2475 const TargetData *TD,
2476 const TargetLibraryInfo *TLI,
2477 const DominatorTree *DT) {
2478 return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Query (TD, TLI, DT),
2482 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
2483 /// fold the result. If not, this returns null.
2484 static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) {
2485 // The type of the GEP pointer operand.
2486 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType());
2487 // The GEP pointer operand is not a pointer, it's a vector of pointers.
2491 // getelementptr P -> P.
2492 if (Ops.size() == 1)
2495 if (isa<UndefValue>(Ops[0])) {
2496 // Compute the (pointer) type returned by the GEP instruction.
2497 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
2498 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
2499 return UndefValue::get(GEPTy);
2502 if (Ops.size() == 2) {
2503 // getelementptr P, 0 -> P.
2504 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
2507 // getelementptr P, N -> P if P points to a type of zero size.
2509 Type *Ty = PtrTy->getElementType();
2510 if (Ty->isSized() && Q.TD->getTypeAllocSize(Ty) == 0)
2515 // Check to see if this is constant foldable.
2516 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2517 if (!isa<Constant>(Ops[i]))
2520 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
2523 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const TargetData *TD,
2524 const TargetLibraryInfo *TLI,
2525 const DominatorTree *DT) {
2526 return ::SimplifyGEPInst(Ops, Query (TD, TLI, DT), RecursionLimit);
2529 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
2530 /// can fold the result. If not, this returns null.
2531 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
2532 ArrayRef<unsigned> Idxs, const Query &Q,
2534 if (Constant *CAgg = dyn_cast<Constant>(Agg))
2535 if (Constant *CVal = dyn_cast<Constant>(Val))
2536 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
2538 // insertvalue x, undef, n -> x
2539 if (match(Val, m_Undef()))
2542 // insertvalue x, (extractvalue y, n), n
2543 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
2544 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
2545 EV->getIndices() == Idxs) {
2546 // insertvalue undef, (extractvalue y, n), n -> y
2547 if (match(Agg, m_Undef()))
2548 return EV->getAggregateOperand();
2550 // insertvalue y, (extractvalue y, n), n -> y
2551 if (Agg == EV->getAggregateOperand())
2558 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
2559 ArrayRef<unsigned> Idxs,
2560 const TargetData *TD,
2561 const TargetLibraryInfo *TLI,
2562 const DominatorTree *DT) {
2563 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query (TD, TLI, DT),
2567 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
2568 static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
2569 // If all of the PHI's incoming values are the same then replace the PHI node
2570 // with the common value.
2571 Value *CommonValue = 0;
2572 bool HasUndefInput = false;
2573 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
2574 Value *Incoming = PN->getIncomingValue(i);
2575 // If the incoming value is the phi node itself, it can safely be skipped.
2576 if (Incoming == PN) continue;
2577 if (isa<UndefValue>(Incoming)) {
2578 // Remember that we saw an undef value, but otherwise ignore them.
2579 HasUndefInput = true;
2582 if (CommonValue && Incoming != CommonValue)
2583 return 0; // Not the same, bail out.
2584 CommonValue = Incoming;
2587 // If CommonValue is null then all of the incoming values were either undef or
2588 // equal to the phi node itself.
2590 return UndefValue::get(PN->getType());
2592 // If we have a PHI node like phi(X, undef, X), where X is defined by some
2593 // instruction, we cannot return X as the result of the PHI node unless it
2594 // dominates the PHI block.
2596 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : 0;
2601 //=== Helper functions for higher up the class hierarchy.
2603 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
2604 /// fold the result. If not, this returns null.
2605 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2606 const Query &Q, unsigned MaxRecurse) {
2608 case Instruction::Add:
2609 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2611 case Instruction::Sub:
2612 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2614 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
2615 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
2616 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
2617 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse);
2618 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
2619 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
2620 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse);
2621 case Instruction::Shl:
2622 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2624 case Instruction::LShr:
2625 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
2626 case Instruction::AShr:
2627 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
2628 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
2629 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
2630 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
2632 if (Constant *CLHS = dyn_cast<Constant>(LHS))
2633 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
2634 Constant *COps[] = {CLHS, CRHS};
2635 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.TD,
2639 // If the operation is associative, try some generic simplifications.
2640 if (Instruction::isAssociative(Opcode))
2641 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
2644 // If the operation is with the result of a select instruction check whether
2645 // operating on either branch of the select always yields the same value.
2646 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2647 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
2650 // If the operation is with the result of a phi instruction, check whether
2651 // operating on all incoming values of the phi always yields the same value.
2652 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2653 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
2660 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2661 const TargetData *TD, const TargetLibraryInfo *TLI,
2662 const DominatorTree *DT) {
2663 return ::SimplifyBinOp(Opcode, LHS, RHS, Query (TD, TLI, DT), RecursionLimit);
2666 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
2667 /// fold the result.
2668 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2669 const Query &Q, unsigned MaxRecurse) {
2670 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
2671 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
2672 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
2675 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2676 const TargetData *TD, const TargetLibraryInfo *TLI,
2677 const DominatorTree *DT) {
2678 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2682 static Value *SimplifyCallInst(CallInst *CI, const Query &) {
2683 // call undef -> undef
2684 if (isa<UndefValue>(CI->getCalledValue()))
2685 return UndefValue::get(CI->getType());
2690 /// SimplifyInstruction - See if we can compute a simplified version of this
2691 /// instruction. If not, this returns null.
2692 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
2693 const TargetLibraryInfo *TLI,
2694 const DominatorTree *DT) {
2697 switch (I->getOpcode()) {
2699 Result = ConstantFoldInstruction(I, TD, TLI);
2701 case Instruction::Add:
2702 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
2703 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2704 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2707 case Instruction::Sub:
2708 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
2709 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2710 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2713 case Instruction::Mul:
2714 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2716 case Instruction::SDiv:
2717 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2719 case Instruction::UDiv:
2720 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2722 case Instruction::FDiv:
2723 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2725 case Instruction::SRem:
2726 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2728 case Instruction::URem:
2729 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2731 case Instruction::FRem:
2732 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2734 case Instruction::Shl:
2735 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
2736 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2737 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2740 case Instruction::LShr:
2741 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
2742 cast<BinaryOperator>(I)->isExact(),
2745 case Instruction::AShr:
2746 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
2747 cast<BinaryOperator>(I)->isExact(),
2750 case Instruction::And:
2751 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2753 case Instruction::Or:
2754 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2756 case Instruction::Xor:
2757 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2759 case Instruction::ICmp:
2760 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
2761 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2763 case Instruction::FCmp:
2764 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
2765 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2767 case Instruction::Select:
2768 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
2769 I->getOperand(2), TD, TLI, DT);
2771 case Instruction::GetElementPtr: {
2772 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
2773 Result = SimplifyGEPInst(Ops, TD, TLI, DT);
2776 case Instruction::InsertValue: {
2777 InsertValueInst *IV = cast<InsertValueInst>(I);
2778 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
2779 IV->getInsertedValueOperand(),
2780 IV->getIndices(), TD, TLI, DT);
2783 case Instruction::PHI:
2784 Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT));
2786 case Instruction::Call:
2787 Result = SimplifyCallInst(cast<CallInst>(I), Query (TD, TLI, DT));
2791 /// If called on unreachable code, the above logic may report that the
2792 /// instruction simplified to itself. Make life easier for users by
2793 /// detecting that case here, returning a safe value instead.
2794 return Result == I ? UndefValue::get(I->getType()) : Result;
2797 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
2798 /// delete the From instruction. In addition to a basic RAUW, this does a
2799 /// recursive simplification of the newly formed instructions. This catches
2800 /// things where one simplification exposes other opportunities. This only
2801 /// simplifies and deletes scalar operations, it does not change the CFG.
2803 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
2804 const TargetData *TD,
2805 const TargetLibraryInfo *TLI,
2806 const DominatorTree *DT) {
2807 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
2809 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
2810 // we can know if it gets deleted out from under us or replaced in a
2811 // recursive simplification.
2812 WeakVH FromHandle(From);
2813 WeakVH ToHandle(To);
2815 while (!From->use_empty()) {
2816 // Update the instruction to use the new value.
2817 Use &TheUse = From->use_begin().getUse();
2818 Instruction *User = cast<Instruction>(TheUse.getUser());
2821 // Check to see if the instruction can be folded due to the operand
2822 // replacement. For example changing (or X, Y) into (or X, -1) can replace
2823 // the 'or' with -1.
2824 Value *SimplifiedVal;
2826 // Sanity check to make sure 'User' doesn't dangle across
2827 // SimplifyInstruction.
2828 AssertingVH<> UserHandle(User);
2830 SimplifiedVal = SimplifyInstruction(User, TD, TLI, DT);
2831 if (SimplifiedVal == 0) continue;
2834 // Recursively simplify this user to the new value.
2835 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, TLI, DT);
2836 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
2839 assert(ToHandle && "To value deleted by recursive simplification?");
2841 // If the recursive simplification ended up revisiting and deleting
2842 // 'From' then we're done.
2847 // If 'From' has value handles referring to it, do a real RAUW to update them.
2848 From->replaceAllUsesWith(To);
2850 From->eraseFromParent();