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/Operator.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/Analysis/InstructionSimplify.h"
24 #include "llvm/Analysis/ConstantFolding.h"
25 #include "llvm/Analysis/Dominators.h"
26 #include "llvm/Analysis/ValueTracking.h"
27 #include "llvm/Support/ConstantRange.h"
28 #include "llvm/Support/PatternMatch.h"
29 #include "llvm/Support/ValueHandle.h"
30 #include "llvm/Target/TargetData.h"
32 using namespace llvm::PatternMatch;
34 enum { RecursionLimit = 3 };
36 STATISTIC(NumExpand, "Number of expansions");
37 STATISTIC(NumFactor , "Number of factorizations");
38 STATISTIC(NumReassoc, "Number of reassociations");
40 static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
41 const TargetLibraryInfo *, const DominatorTree *,
43 static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
44 const TargetLibraryInfo *, const DominatorTree *,
46 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
47 const TargetLibraryInfo *, const DominatorTree *,
49 static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
50 const TargetLibraryInfo *, const DominatorTree *,
52 static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
53 const TargetLibraryInfo *, const DominatorTree *,
56 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
57 /// a vector with every element false, as appropriate for the type.
58 static Constant *getFalse(Type *Ty) {
59 assert(Ty->getScalarType()->isIntegerTy(1) &&
60 "Expected i1 type or a vector of i1!");
61 return Constant::getNullValue(Ty);
64 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
65 /// a vector with every element true, as appropriate for the type.
66 static Constant *getTrue(Type *Ty) {
67 assert(Ty->getScalarType()->isIntegerTy(1) &&
68 "Expected i1 type or a vector of i1!");
69 return Constant::getAllOnesValue(Ty);
72 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
73 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
75 CmpInst *Cmp = dyn_cast<CmpInst>(V);
78 CmpInst::Predicate CPred = Cmp->getPredicate();
79 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
80 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
82 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
86 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
87 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
88 Instruction *I = dyn_cast<Instruction>(V);
90 // Arguments and constants dominate all instructions.
93 // If we have a DominatorTree then do a precise test.
95 return DT->dominates(I, P);
97 // Otherwise, if the instruction is in the entry block, and is not an invoke,
98 // then it obviously dominates all phi nodes.
99 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
106 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
107 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
108 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
109 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
110 /// Returns the simplified value, or null if no simplification was performed.
111 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
112 unsigned OpcToExpand, const TargetData *TD,
113 const TargetLibraryInfo *TLI, const DominatorTree *DT,
114 unsigned MaxRecurse) {
115 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
116 // Recursion is always used, so bail out at once if we already hit the limit.
120 // Check whether the expression has the form "(A op' B) op C".
121 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
122 if (Op0->getOpcode() == OpcodeToExpand) {
123 // It does! Try turning it into "(A op C) op' (B op C)".
124 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
125 // Do "A op C" and "B op C" both simplify?
126 if (Value *L = SimplifyBinOp(Opcode, A, C, TD, TLI, DT, MaxRecurse))
127 if (Value *R = SimplifyBinOp(Opcode, B, C, TD, TLI, DT, MaxRecurse)) {
128 // They do! Return "L op' R" if it simplifies or is already available.
129 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
130 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
131 && L == B && R == A)) {
135 // Otherwise return "L op' R" if it simplifies.
136 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, TLI, DT,
144 // Check whether the expression has the form "A op (B op' C)".
145 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
146 if (Op1->getOpcode() == OpcodeToExpand) {
147 // It does! Try turning it into "(A op B) op' (A op C)".
148 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
149 // Do "A op B" and "A op C" both simplify?
150 if (Value *L = SimplifyBinOp(Opcode, A, B, TD, TLI, DT, MaxRecurse))
151 if (Value *R = SimplifyBinOp(Opcode, A, C, TD, TLI, DT, MaxRecurse)) {
152 // They do! Return "L op' R" if it simplifies or is already available.
153 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
154 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
155 && L == C && R == B)) {
159 // Otherwise return "L op' R" if it simplifies.
160 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, TLI, DT,
171 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
172 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
173 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
174 /// Returns the simplified value, or null if no simplification was performed.
175 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
176 unsigned OpcToExtract, const TargetData *TD,
177 const TargetLibraryInfo *TLI,
178 const DominatorTree *DT,
179 unsigned MaxRecurse) {
180 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
181 // Recursion is always used, so bail out at once if we already hit the limit.
185 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
186 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
188 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
189 !Op1 || Op1->getOpcode() != OpcodeToExtract)
192 // The expression has the form "(A op' B) op (C op' D)".
193 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
194 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
196 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
197 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
198 // commutative case, "(A op' B) op (C op' A)"?
199 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
200 Value *DD = A == C ? D : C;
201 // Form "A op' (B op DD)" if it simplifies completely.
202 // Does "B op DD" simplify?
203 if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, TLI, DT, MaxRecurse)) {
204 // It does! Return "A op' V" if it simplifies or is already available.
205 // If V equals B then "A op' V" is just the LHS. If V equals DD then
206 // "A op' V" is just the RHS.
207 if (V == B || V == DD) {
209 return V == B ? LHS : RHS;
211 // Otherwise return "A op' V" if it simplifies.
212 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, TLI, DT,
220 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
221 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
222 // commutative case, "(A op' B) op (B op' D)"?
223 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
224 Value *CC = B == D ? C : D;
225 // Form "(A op CC) op' B" if it simplifies completely..
226 // Does "A op CC" simplify?
227 if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, TLI, DT, MaxRecurse)) {
228 // It does! Return "V op' B" if it simplifies or is already available.
229 // If V equals A then "V op' B" is just the LHS. If V equals CC then
230 // "V op' B" is just the RHS.
231 if (V == A || V == CC) {
233 return V == A ? LHS : RHS;
235 // Otherwise return "V op' B" if it simplifies.
236 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, TLI, DT,
247 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
248 /// operations. Returns the simpler value, or null if none was found.
249 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
250 const TargetData *TD,
251 const TargetLibraryInfo *TLI,
252 const DominatorTree *DT,
253 unsigned MaxRecurse) {
254 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
255 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
257 // Recursion is always used, so bail out at once if we already hit the limit.
261 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
262 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
264 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
265 if (Op0 && Op0->getOpcode() == Opcode) {
266 Value *A = Op0->getOperand(0);
267 Value *B = Op0->getOperand(1);
270 // Does "B op C" simplify?
271 if (Value *V = SimplifyBinOp(Opcode, B, C, TD, TLI, DT, MaxRecurse)) {
272 // It does! Return "A op V" if it simplifies or is already available.
273 // If V equals B then "A op V" is just the LHS.
274 if (V == B) return LHS;
275 // Otherwise return "A op V" if it simplifies.
276 if (Value *W = SimplifyBinOp(Opcode, A, V, TD, TLI, DT, MaxRecurse)) {
283 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
284 if (Op1 && Op1->getOpcode() == Opcode) {
286 Value *B = Op1->getOperand(0);
287 Value *C = Op1->getOperand(1);
289 // Does "A op B" simplify?
290 if (Value *V = SimplifyBinOp(Opcode, A, B, TD, TLI, DT, MaxRecurse)) {
291 // It does! Return "V op C" if it simplifies or is already available.
292 // If V equals B then "V op C" is just the RHS.
293 if (V == B) return RHS;
294 // Otherwise return "V op C" if it simplifies.
295 if (Value *W = SimplifyBinOp(Opcode, V, C, TD, TLI, DT, MaxRecurse)) {
302 // The remaining transforms require commutativity as well as associativity.
303 if (!Instruction::isCommutative(Opcode))
306 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
307 if (Op0 && Op0->getOpcode() == Opcode) {
308 Value *A = Op0->getOperand(0);
309 Value *B = Op0->getOperand(1);
312 // Does "C op A" simplify?
313 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, TLI, DT, MaxRecurse)) {
314 // It does! Return "V op B" if it simplifies or is already available.
315 // If V equals A then "V op B" is just the LHS.
316 if (V == A) return LHS;
317 // Otherwise return "V op B" if it simplifies.
318 if (Value *W = SimplifyBinOp(Opcode, V, B, TD, TLI, DT, MaxRecurse)) {
325 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
326 if (Op1 && Op1->getOpcode() == Opcode) {
328 Value *B = Op1->getOperand(0);
329 Value *C = Op1->getOperand(1);
331 // Does "C op A" simplify?
332 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, TLI, DT, MaxRecurse)) {
333 // It does! Return "B op V" if it simplifies or is already available.
334 // If V equals C then "B op V" is just the RHS.
335 if (V == C) return RHS;
336 // Otherwise return "B op V" if it simplifies.
337 if (Value *W = SimplifyBinOp(Opcode, B, V, TD, TLI, DT, MaxRecurse)) {
347 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
348 /// instruction as an operand, try to simplify the binop by seeing whether
349 /// evaluating it on both branches of the select results in the same value.
350 /// Returns the common value if so, otherwise returns null.
351 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
352 const TargetData *TD,
353 const TargetLibraryInfo *TLI,
354 const DominatorTree *DT,
355 unsigned MaxRecurse) {
356 // Recursion is always used, so bail out at once if we already hit the limit.
361 if (isa<SelectInst>(LHS)) {
362 SI = cast<SelectInst>(LHS);
364 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
365 SI = cast<SelectInst>(RHS);
368 // Evaluate the BinOp on the true and false branches of the select.
372 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, TLI, DT, MaxRecurse);
373 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, TLI, DT, MaxRecurse);
375 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, TLI, DT, MaxRecurse);
376 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, TLI, DT, MaxRecurse);
379 // If they simplified to the same value, then return the common value.
380 // If they both failed to simplify then return null.
384 // If one branch simplified to undef, return the other one.
385 if (TV && isa<UndefValue>(TV))
387 if (FV && isa<UndefValue>(FV))
390 // If applying the operation did not change the true and false select values,
391 // then the result of the binop is the select itself.
392 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
395 // If one branch simplified and the other did not, and the simplified
396 // value is equal to the unsimplified one, return the simplified value.
397 // For example, select (cond, X, X & Z) & Z -> X & Z.
398 if ((FV && !TV) || (TV && !FV)) {
399 // Check that the simplified value has the form "X op Y" where "op" is the
400 // same as the original operation.
401 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
402 if (Simplified && Simplified->getOpcode() == Opcode) {
403 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
404 // We already know that "op" is the same as for the simplified value. See
405 // if the operands match too. If so, return the simplified value.
406 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
407 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
408 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
409 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
410 Simplified->getOperand(1) == UnsimplifiedRHS)
412 if (Simplified->isCommutative() &&
413 Simplified->getOperand(1) == UnsimplifiedLHS &&
414 Simplified->getOperand(0) == UnsimplifiedRHS)
422 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
423 /// try to simplify the comparison by seeing whether both branches of the select
424 /// result in the same value. Returns the common value if so, otherwise returns
426 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
427 Value *RHS, const TargetData *TD,
428 const TargetLibraryInfo *TLI,
429 const DominatorTree *DT,
430 unsigned MaxRecurse) {
431 // Recursion is always used, so bail out at once if we already hit the limit.
435 // Make sure the select is on the LHS.
436 if (!isa<SelectInst>(LHS)) {
438 Pred = CmpInst::getSwappedPredicate(Pred);
440 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
441 SelectInst *SI = cast<SelectInst>(LHS);
442 Value *Cond = SI->getCondition();
443 Value *TV = SI->getTrueValue();
444 Value *FV = SI->getFalseValue();
446 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
447 // Does "cmp TV, RHS" simplify?
448 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, TD, TLI, DT, MaxRecurse);
450 // It not only simplified, it simplified to the select condition. Replace
452 TCmp = getTrue(Cond->getType());
454 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
455 // condition then we can replace it with 'true'. Otherwise give up.
456 if (!isSameCompare(Cond, Pred, TV, RHS))
458 TCmp = getTrue(Cond->getType());
461 // Does "cmp FV, RHS" simplify?
462 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, TD, TLI, DT, MaxRecurse);
464 // It not only simplified, it simplified to the select condition. Replace
466 FCmp = getFalse(Cond->getType());
468 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
469 // condition then we can replace it with 'false'. Otherwise give up.
470 if (!isSameCompare(Cond, Pred, FV, RHS))
472 FCmp = getFalse(Cond->getType());
475 // If both sides simplified to the same value, then use it as the result of
476 // the original comparison.
479 // If the false value simplified to false, then the result of the compare
480 // is equal to "Cond && TCmp". This also catches the case when the false
481 // value simplified to false and the true value to true, returning "Cond".
482 if (match(FCmp, m_Zero()))
483 if (Value *V = SimplifyAndInst(Cond, TCmp, TD, TLI, DT, MaxRecurse))
485 // If the true value simplified to true, then the result of the compare
486 // is equal to "Cond || FCmp".
487 if (match(TCmp, m_One()))
488 if (Value *V = SimplifyOrInst(Cond, FCmp, TD, TLI, DT, MaxRecurse))
490 // Finally, if the false value simplified to true and the true value to
491 // false, then the result of the compare is equal to "!Cond".
492 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
494 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
495 TD, TLI, DT, MaxRecurse))
501 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
502 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
503 /// it on the incoming phi values yields the same result for every value. If so
504 /// returns the common value, otherwise returns null.
505 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
506 const TargetData *TD,
507 const TargetLibraryInfo *TLI,
508 const DominatorTree *DT,
509 unsigned MaxRecurse) {
510 // Recursion is always used, so bail out at once if we already hit the limit.
515 if (isa<PHINode>(LHS)) {
516 PI = cast<PHINode>(LHS);
517 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
518 if (!ValueDominatesPHI(RHS, PI, DT))
521 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
522 PI = cast<PHINode>(RHS);
523 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
524 if (!ValueDominatesPHI(LHS, PI, DT))
528 // Evaluate the BinOp on the incoming phi values.
529 Value *CommonValue = 0;
530 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
531 Value *Incoming = PI->getIncomingValue(i);
532 // If the incoming value is the phi node itself, it can safely be skipped.
533 if (Incoming == PI) continue;
534 Value *V = PI == LHS ?
535 SimplifyBinOp(Opcode, Incoming, RHS, TD, TLI, DT, MaxRecurse) :
536 SimplifyBinOp(Opcode, LHS, Incoming, TD, TLI, DT, MaxRecurse);
537 // If the operation failed to simplify, or simplified to a different value
538 // to previously, then give up.
539 if (!V || (CommonValue && V != CommonValue))
547 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
548 /// try to simplify the comparison by seeing whether comparing with all of the
549 /// incoming phi values yields the same result every time. If so returns the
550 /// common result, otherwise returns null.
551 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
552 const TargetData *TD,
553 const TargetLibraryInfo *TLI,
554 const DominatorTree *DT,
555 unsigned MaxRecurse) {
556 // Recursion is always used, so bail out at once if we already hit the limit.
560 // Make sure the phi is on the LHS.
561 if (!isa<PHINode>(LHS)) {
563 Pred = CmpInst::getSwappedPredicate(Pred);
565 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
566 PHINode *PI = cast<PHINode>(LHS);
568 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
569 if (!ValueDominatesPHI(RHS, PI, DT))
572 // Evaluate the BinOp on the incoming phi values.
573 Value *CommonValue = 0;
574 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
575 Value *Incoming = PI->getIncomingValue(i);
576 // If the incoming value is the phi node itself, it can safely be skipped.
577 if (Incoming == PI) continue;
578 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, TLI, DT, MaxRecurse);
579 // If the operation failed to simplify, or simplified to a different value
580 // to previously, then give up.
581 if (!V || (CommonValue && V != CommonValue))
589 /// SimplifyAddInst - Given operands for an Add, see if we can
590 /// fold the result. If not, this returns null.
591 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
592 const TargetData *TD,
593 const TargetLibraryInfo *TLI,
594 const DominatorTree *DT,
595 unsigned MaxRecurse) {
596 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
597 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
598 Constant *Ops[] = { CLHS, CRHS };
599 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
603 // Canonicalize the constant to the RHS.
607 // X + undef -> undef
608 if (match(Op1, m_Undef()))
612 if (match(Op1, m_Zero()))
619 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
620 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
623 // X + ~X -> -1 since ~X = -X-1
624 if (match(Op0, m_Not(m_Specific(Op1))) ||
625 match(Op1, m_Not(m_Specific(Op0))))
626 return Constant::getAllOnesValue(Op0->getType());
629 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
630 if (Value *V = SimplifyXorInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
633 // Try some generic simplifications for associative operations.
634 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, TLI, DT,
638 // Mul distributes over Add. Try some generic simplifications based on this.
639 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
640 TD, TLI, DT, MaxRecurse))
643 // Threading Add over selects and phi nodes is pointless, so don't bother.
644 // Threading over the select in "A + select(cond, B, C)" means evaluating
645 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
646 // only if B and C are equal. If B and C are equal then (since we assume
647 // that operands have already been simplified) "select(cond, B, C)" should
648 // have been simplified to the common value of B and C already. Analysing
649 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
650 // for threading over phi nodes.
655 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
656 const TargetData *TD, const TargetLibraryInfo *TLI,
657 const DominatorTree *DT) {
658 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
661 /// SimplifySubInst - Given operands for a Sub, see if we can
662 /// fold the result. If not, this returns null.
663 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
664 const TargetData *TD,
665 const TargetLibraryInfo *TLI,
666 const DominatorTree *DT,
667 unsigned MaxRecurse) {
668 if (Constant *CLHS = dyn_cast<Constant>(Op0))
669 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
670 Constant *Ops[] = { CLHS, CRHS };
671 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
675 // X - undef -> undef
676 // undef - X -> undef
677 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
678 return UndefValue::get(Op0->getType());
681 if (match(Op1, m_Zero()))
686 return Constant::getNullValue(Op0->getType());
691 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
692 match(Op0, m_Shl(m_Specific(Op1), m_One())))
695 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
696 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
697 Value *Y = 0, *Z = Op1;
698 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
699 // See if "V === Y - Z" simplifies.
700 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, TLI, DT, MaxRecurse-1))
701 // It does! Now see if "X + V" simplifies.
702 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, TLI, DT,
704 // It does, we successfully reassociated!
708 // See if "V === X - Z" simplifies.
709 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, TLI, DT, MaxRecurse-1))
710 // It does! Now see if "Y + V" simplifies.
711 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, TLI, DT,
713 // It does, we successfully reassociated!
719 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
720 // For example, X - (X + 1) -> -1
722 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
723 // See if "V === X - Y" simplifies.
724 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, TLI, DT, MaxRecurse-1))
725 // It does! Now see if "V - Z" simplifies.
726 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, TLI, DT,
728 // It does, we successfully reassociated!
732 // See if "V === X - Z" simplifies.
733 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, TLI, DT, MaxRecurse-1))
734 // It does! Now see if "V - Y" simplifies.
735 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, TLI, DT,
737 // It does, we successfully reassociated!
743 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
744 // For example, X - (X - Y) -> Y.
746 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
747 // See if "V === Z - X" simplifies.
748 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, TLI, DT, MaxRecurse-1))
749 // It does! Now see if "V + Y" simplifies.
750 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, TLI, DT,
752 // It does, we successfully reassociated!
757 // Mul distributes over Sub. Try some generic simplifications based on this.
758 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
759 TD, TLI, DT, MaxRecurse))
763 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
764 if (Value *V = SimplifyXorInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
767 // Threading Sub over selects and phi nodes is pointless, so don't bother.
768 // Threading over the select in "A - select(cond, B, C)" means evaluating
769 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
770 // only if B and C are equal. If B and C are equal then (since we assume
771 // that operands have already been simplified) "select(cond, B, C)" should
772 // have been simplified to the common value of B and C already. Analysing
773 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
774 // for threading over phi nodes.
779 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
780 const TargetData *TD,
781 const TargetLibraryInfo *TLI,
782 const DominatorTree *DT) {
783 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
786 /// SimplifyMulInst - Given operands for a Mul, see if we can
787 /// fold the result. If not, this returns null.
788 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
789 const TargetLibraryInfo *TLI,
790 const DominatorTree *DT, unsigned MaxRecurse) {
791 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
792 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
793 Constant *Ops[] = { CLHS, CRHS };
794 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
798 // Canonicalize the constant to the RHS.
803 if (match(Op1, m_Undef()))
804 return Constant::getNullValue(Op0->getType());
807 if (match(Op1, m_Zero()))
811 if (match(Op1, m_One()))
814 // (X / Y) * Y -> X if the division is exact.
816 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
817 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
821 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
822 if (Value *V = SimplifyAndInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
825 // Try some generic simplifications for associative operations.
826 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, TLI, DT,
830 // Mul distributes over Add. Try some generic simplifications based on this.
831 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
832 TD, TLI, DT, MaxRecurse))
835 // If the operation is with the result of a select instruction, check whether
836 // operating on either branch of the select always yields the same value.
837 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
838 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, TLI, DT,
842 // If the operation is with the result of a phi instruction, check whether
843 // operating on all incoming values of the phi always yields the same value.
844 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
845 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, TLI, DT,
852 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
853 const TargetLibraryInfo *TLI,
854 const DominatorTree *DT) {
855 return ::SimplifyMulInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
858 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
859 /// fold the result. If not, this returns null.
860 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
861 const TargetData *TD, const TargetLibraryInfo *TLI,
862 const DominatorTree *DT, unsigned MaxRecurse) {
863 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
864 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
865 Constant *Ops[] = { C0, C1 };
866 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
870 bool isSigned = Opcode == Instruction::SDiv;
872 // X / undef -> undef
873 if (match(Op1, m_Undef()))
877 if (match(Op0, m_Undef()))
878 return Constant::getNullValue(Op0->getType());
880 // 0 / X -> 0, we don't need to preserve faults!
881 if (match(Op0, m_Zero()))
885 if (match(Op1, m_One()))
888 if (Op0->getType()->isIntegerTy(1))
889 // It can't be division by zero, hence it must be division by one.
894 return ConstantInt::get(Op0->getType(), 1);
896 // (X * Y) / Y -> X if the multiplication does not overflow.
897 Value *X = 0, *Y = 0;
898 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
899 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
900 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
901 // If the Mul knows it does not overflow, then we are good to go.
902 if ((isSigned && Mul->hasNoSignedWrap()) ||
903 (!isSigned && Mul->hasNoUnsignedWrap()))
905 // If X has the form X = A / Y then X * Y cannot overflow.
906 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
907 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
911 // (X rem Y) / Y -> 0
912 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
913 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
914 return Constant::getNullValue(Op0->getType());
916 // If the operation is with the result of a select instruction, check whether
917 // operating on either branch of the select always yields the same value.
918 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
919 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT,
923 // If the operation is with the result of a phi instruction, check whether
924 // operating on all incoming values of the phi always yields the same value.
925 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
926 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT,
933 /// SimplifySDivInst - Given operands for an SDiv, see if we can
934 /// fold the result. If not, this returns null.
935 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
936 const TargetLibraryInfo *TLI,
937 const DominatorTree *DT, unsigned MaxRecurse) {
938 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, TLI, DT,
945 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
946 const TargetLibraryInfo *TLI,
947 const DominatorTree *DT) {
948 return ::SimplifySDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
951 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
952 /// fold the result. If not, this returns null.
953 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
954 const TargetLibraryInfo *TLI,
955 const DominatorTree *DT, unsigned MaxRecurse) {
956 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, TLI, DT,
963 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
964 const TargetLibraryInfo *TLI,
965 const DominatorTree *DT) {
966 return ::SimplifyUDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
969 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *,
970 const TargetLibraryInfo *,
971 const DominatorTree *, unsigned) {
972 // undef / X -> undef (the undef could be a snan).
973 if (match(Op0, m_Undef()))
976 // X / undef -> undef
977 if (match(Op1, m_Undef()))
983 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
984 const TargetLibraryInfo *TLI,
985 const DominatorTree *DT) {
986 return ::SimplifyFDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
989 /// SimplifyRem - Given operands for an SRem or URem, see if we can
990 /// fold the result. If not, this returns null.
991 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
992 const TargetData *TD, const TargetLibraryInfo *TLI,
993 const DominatorTree *DT, unsigned MaxRecurse) {
994 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
995 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
996 Constant *Ops[] = { C0, C1 };
997 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
1001 // X % undef -> undef
1002 if (match(Op1, m_Undef()))
1006 if (match(Op0, m_Undef()))
1007 return Constant::getNullValue(Op0->getType());
1009 // 0 % X -> 0, we don't need to preserve faults!
1010 if (match(Op0, m_Zero()))
1013 // X % 0 -> undef, we don't need to preserve faults!
1014 if (match(Op1, m_Zero()))
1015 return UndefValue::get(Op0->getType());
1018 if (match(Op1, m_One()))
1019 return Constant::getNullValue(Op0->getType());
1021 if (Op0->getType()->isIntegerTy(1))
1022 // It can't be remainder by zero, hence it must be remainder by one.
1023 return Constant::getNullValue(Op0->getType());
1027 return Constant::getNullValue(Op0->getType());
1029 // If the operation is with the result of a select instruction, check whether
1030 // operating on either branch of the select always yields the same value.
1031 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1032 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1035 // If the operation is with the result of a phi instruction, check whether
1036 // operating on all incoming values of the phi always yields the same value.
1037 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1038 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1044 /// SimplifySRemInst - Given operands for an SRem, see if we can
1045 /// fold the result. If not, this returns null.
1046 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1047 const TargetLibraryInfo *TLI,
1048 const DominatorTree *DT,
1049 unsigned MaxRecurse) {
1050 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, TD, TLI, DT, MaxRecurse))
1056 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1057 const TargetLibraryInfo *TLI,
1058 const DominatorTree *DT) {
1059 return ::SimplifySRemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1062 /// SimplifyURemInst - Given operands for a URem, see if we can
1063 /// fold the result. If not, this returns null.
1064 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1065 const TargetLibraryInfo *TLI,
1066 const DominatorTree *DT,
1067 unsigned MaxRecurse) {
1068 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, TD, TLI, DT, MaxRecurse))
1074 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1075 const TargetLibraryInfo *TLI,
1076 const DominatorTree *DT) {
1077 return ::SimplifyURemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1080 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *,
1081 const TargetLibraryInfo *,
1082 const DominatorTree *,
1084 // undef % X -> undef (the undef could be a snan).
1085 if (match(Op0, m_Undef()))
1088 // X % undef -> undef
1089 if (match(Op1, m_Undef()))
1095 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1096 const TargetLibraryInfo *TLI,
1097 const DominatorTree *DT) {
1098 return ::SimplifyFRemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1101 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1102 /// fold the result. If not, this returns null.
1103 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1104 const TargetData *TD, const TargetLibraryInfo *TLI,
1105 const DominatorTree *DT, unsigned MaxRecurse) {
1106 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1107 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1108 Constant *Ops[] = { C0, C1 };
1109 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
1113 // 0 shift by X -> 0
1114 if (match(Op0, m_Zero()))
1117 // X shift by 0 -> X
1118 if (match(Op1, m_Zero()))
1121 // X shift by undef -> undef because it may shift by the bitwidth.
1122 if (match(Op1, m_Undef()))
1125 // Shifting by the bitwidth or more is undefined.
1126 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
1127 if (CI->getValue().getLimitedValue() >=
1128 Op0->getType()->getScalarSizeInBits())
1129 return UndefValue::get(Op0->getType());
1131 // If the operation is with the result of a select instruction, check whether
1132 // operating on either branch of the select always yields the same value.
1133 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1134 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1137 // If the operation is with the result of a phi instruction, check whether
1138 // operating on all incoming values of the phi always yields the same value.
1139 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1140 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1146 /// SimplifyShlInst - Given operands for an Shl, see if we can
1147 /// fold the result. If not, this returns null.
1148 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1149 const TargetData *TD,
1150 const TargetLibraryInfo *TLI,
1151 const DominatorTree *DT, unsigned MaxRecurse) {
1152 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, TLI, DT, MaxRecurse))
1156 if (match(Op0, m_Undef()))
1157 return Constant::getNullValue(Op0->getType());
1159 // (X >> A) << A -> X
1161 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1166 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1167 const TargetData *TD, const TargetLibraryInfo *TLI,
1168 const DominatorTree *DT) {
1169 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
1172 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1173 /// fold the result. If not, this returns null.
1174 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1175 const TargetData *TD,
1176 const TargetLibraryInfo *TLI,
1177 const DominatorTree *DT,
1178 unsigned MaxRecurse) {
1179 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, TLI, DT, MaxRecurse))
1183 if (match(Op0, m_Undef()))
1184 return Constant::getNullValue(Op0->getType());
1186 // (X << A) >> A -> X
1188 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1189 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
1195 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1196 const TargetData *TD,
1197 const TargetLibraryInfo *TLI,
1198 const DominatorTree *DT) {
1199 return ::SimplifyLShrInst(Op0, Op1, isExact, TD, TLI, DT, RecursionLimit);
1202 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1203 /// fold the result. If not, this returns null.
1204 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1205 const TargetData *TD,
1206 const TargetLibraryInfo *TLI,
1207 const DominatorTree *DT,
1208 unsigned MaxRecurse) {
1209 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, TLI, DT, MaxRecurse))
1212 // all ones >>a X -> all ones
1213 if (match(Op0, m_AllOnes()))
1216 // undef >>a X -> all ones
1217 if (match(Op0, m_Undef()))
1218 return Constant::getAllOnesValue(Op0->getType());
1220 // (X << A) >> A -> X
1222 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1223 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
1229 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1230 const TargetData *TD,
1231 const TargetLibraryInfo *TLI,
1232 const DominatorTree *DT) {
1233 return ::SimplifyAShrInst(Op0, Op1, isExact, TD, TLI, DT, RecursionLimit);
1236 /// SimplifyAndInst - Given operands for an And, see if we can
1237 /// fold the result. If not, this returns null.
1238 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1239 const TargetLibraryInfo *TLI,
1240 const DominatorTree *DT,
1241 unsigned MaxRecurse) {
1242 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1243 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1244 Constant *Ops[] = { CLHS, CRHS };
1245 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1249 // Canonicalize the constant to the RHS.
1250 std::swap(Op0, Op1);
1254 if (match(Op1, m_Undef()))
1255 return Constant::getNullValue(Op0->getType());
1262 if (match(Op1, m_Zero()))
1266 if (match(Op1, m_AllOnes()))
1269 // A & ~A = ~A & A = 0
1270 if (match(Op0, m_Not(m_Specific(Op1))) ||
1271 match(Op1, m_Not(m_Specific(Op0))))
1272 return Constant::getNullValue(Op0->getType());
1275 Value *A = 0, *B = 0;
1276 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1277 (A == Op1 || B == Op1))
1281 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1282 (A == Op0 || B == Op0))
1285 // A & (-A) = A if A is a power of two or zero.
1286 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1287 match(Op1, m_Neg(m_Specific(Op0)))) {
1288 if (isPowerOfTwo(Op0, TD, /*OrZero*/true))
1290 if (isPowerOfTwo(Op1, TD, /*OrZero*/true))
1294 // Try some generic simplifications for associative operations.
1295 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, TLI,
1299 // And distributes over Or. Try some generic simplifications based on this.
1300 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1301 TD, TLI, DT, MaxRecurse))
1304 // And distributes over Xor. Try some generic simplifications based on this.
1305 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1306 TD, TLI, DT, MaxRecurse))
1309 // Or distributes over And. Try some generic simplifications based on this.
1310 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1311 TD, TLI, DT, MaxRecurse))
1314 // If the operation is with the result of a select instruction, check whether
1315 // operating on either branch of the select always yields the same value.
1316 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1317 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, TLI,
1321 // If the operation is with the result of a phi instruction, check whether
1322 // operating on all incoming values of the phi always yields the same value.
1323 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1324 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, TLI, DT,
1331 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1332 const TargetLibraryInfo *TLI,
1333 const DominatorTree *DT) {
1334 return ::SimplifyAndInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1337 /// SimplifyOrInst - Given operands for an Or, see if we can
1338 /// fold the result. If not, this returns null.
1339 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1340 const TargetLibraryInfo *TLI,
1341 const DominatorTree *DT, unsigned MaxRecurse) {
1342 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1343 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1344 Constant *Ops[] = { CLHS, CRHS };
1345 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1349 // Canonicalize the constant to the RHS.
1350 std::swap(Op0, Op1);
1354 if (match(Op1, m_Undef()))
1355 return Constant::getAllOnesValue(Op0->getType());
1362 if (match(Op1, m_Zero()))
1366 if (match(Op1, m_AllOnes()))
1369 // A | ~A = ~A | A = -1
1370 if (match(Op0, m_Not(m_Specific(Op1))) ||
1371 match(Op1, m_Not(m_Specific(Op0))))
1372 return Constant::getAllOnesValue(Op0->getType());
1375 Value *A = 0, *B = 0;
1376 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1377 (A == Op1 || B == Op1))
1381 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1382 (A == Op0 || B == Op0))
1385 // ~(A & ?) | A = -1
1386 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1387 (A == Op1 || B == Op1))
1388 return Constant::getAllOnesValue(Op1->getType());
1390 // A | ~(A & ?) = -1
1391 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1392 (A == Op0 || B == Op0))
1393 return Constant::getAllOnesValue(Op0->getType());
1395 // Try some generic simplifications for associative operations.
1396 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, TLI,
1400 // Or distributes over And. Try some generic simplifications based on this.
1401 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, TD,
1402 TLI, DT, MaxRecurse))
1405 // And distributes over Or. Try some generic simplifications based on this.
1406 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1407 TD, TLI, DT, MaxRecurse))
1410 // If the operation is with the result of a select instruction, check whether
1411 // operating on either branch of the select always yields the same value.
1412 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1413 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, TLI, DT,
1417 // If the operation is with the result of a phi instruction, check whether
1418 // operating on all incoming values of the phi always yields the same value.
1419 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1420 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, TLI, DT,
1427 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1428 const TargetLibraryInfo *TLI,
1429 const DominatorTree *DT) {
1430 return ::SimplifyOrInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1433 /// SimplifyXorInst - Given operands for a Xor, see if we can
1434 /// fold the result. If not, this returns null.
1435 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1436 const TargetLibraryInfo *TLI,
1437 const DominatorTree *DT, unsigned MaxRecurse) {
1438 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1439 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1440 Constant *Ops[] = { CLHS, CRHS };
1441 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1445 // Canonicalize the constant to the RHS.
1446 std::swap(Op0, Op1);
1449 // A ^ undef -> undef
1450 if (match(Op1, m_Undef()))
1454 if (match(Op1, m_Zero()))
1459 return Constant::getNullValue(Op0->getType());
1461 // A ^ ~A = ~A ^ A = -1
1462 if (match(Op0, m_Not(m_Specific(Op1))) ||
1463 match(Op1, m_Not(m_Specific(Op0))))
1464 return Constant::getAllOnesValue(Op0->getType());
1466 // Try some generic simplifications for associative operations.
1467 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, TLI,
1471 // And distributes over Xor. Try some generic simplifications based on this.
1472 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1473 TD, TLI, DT, MaxRecurse))
1476 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1477 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1478 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1479 // only if B and C are equal. If B and C are equal then (since we assume
1480 // that operands have already been simplified) "select(cond, B, C)" should
1481 // have been simplified to the common value of B and C already. Analysing
1482 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1483 // for threading over phi nodes.
1488 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1489 const TargetLibraryInfo *TLI,
1490 const DominatorTree *DT) {
1491 return ::SimplifyXorInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1494 static Type *GetCompareTy(Value *Op) {
1495 return CmpInst::makeCmpResultType(Op->getType());
1498 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1499 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1500 /// otherwise return null. Helper function for analyzing max/min idioms.
1501 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1502 Value *LHS, Value *RHS) {
1503 SelectInst *SI = dyn_cast<SelectInst>(V);
1506 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1509 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1510 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1512 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1513 LHS == CmpRHS && RHS == CmpLHS)
1518 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1519 /// fold the result. If not, this returns null.
1520 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1521 const TargetData *TD,
1522 const TargetLibraryInfo *TLI,
1523 const DominatorTree *DT,
1524 unsigned MaxRecurse) {
1525 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1526 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1528 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1529 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1530 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD, TLI);
1532 // If we have a constant, make sure it is on the RHS.
1533 std::swap(LHS, RHS);
1534 Pred = CmpInst::getSwappedPredicate(Pred);
1537 Type *ITy = GetCompareTy(LHS); // The return type.
1538 Type *OpTy = LHS->getType(); // The operand type.
1540 // icmp X, X -> true/false
1541 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1542 // because X could be 0.
1543 if (LHS == RHS || isa<UndefValue>(RHS))
1544 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1546 // Special case logic when the operands have i1 type.
1547 if (OpTy->getScalarType()->isIntegerTy(1)) {
1550 case ICmpInst::ICMP_EQ:
1552 if (match(RHS, m_One()))
1555 case ICmpInst::ICMP_NE:
1557 if (match(RHS, m_Zero()))
1560 case ICmpInst::ICMP_UGT:
1562 if (match(RHS, m_Zero()))
1565 case ICmpInst::ICMP_UGE:
1567 if (match(RHS, m_One()))
1570 case ICmpInst::ICMP_SLT:
1572 if (match(RHS, m_Zero()))
1575 case ICmpInst::ICMP_SLE:
1577 if (match(RHS, m_One()))
1583 // icmp <alloca*>, <global/alloca*/null> - Different stack variables have
1584 // different addresses, and what's more the address of a stack variable is
1585 // never null or equal to the address of a global. Note that generalizing
1586 // to the case where LHS is a global variable address or null is pointless,
1587 // since if both LHS and RHS are constants then we already constant folded
1588 // the compare, and if only one of them is then we moved it to RHS already.
1589 if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
1590 isa<ConstantPointerNull>(RHS)))
1591 // We already know that LHS != RHS.
1592 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
1594 // If we are comparing with zero then try hard since this is a common case.
1595 if (match(RHS, m_Zero())) {
1596 bool LHSKnownNonNegative, LHSKnownNegative;
1599 assert(false && "Unknown ICmp predicate!");
1600 case ICmpInst::ICMP_ULT:
1601 return getFalse(ITy);
1602 case ICmpInst::ICMP_UGE:
1603 return getTrue(ITy);
1604 case ICmpInst::ICMP_EQ:
1605 case ICmpInst::ICMP_ULE:
1606 if (isKnownNonZero(LHS, TD))
1607 return getFalse(ITy);
1609 case ICmpInst::ICMP_NE:
1610 case ICmpInst::ICMP_UGT:
1611 if (isKnownNonZero(LHS, TD))
1612 return getTrue(ITy);
1614 case ICmpInst::ICMP_SLT:
1615 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1616 if (LHSKnownNegative)
1617 return getTrue(ITy);
1618 if (LHSKnownNonNegative)
1619 return getFalse(ITy);
1621 case ICmpInst::ICMP_SLE:
1622 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1623 if (LHSKnownNegative)
1624 return getTrue(ITy);
1625 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1626 return getFalse(ITy);
1628 case ICmpInst::ICMP_SGE:
1629 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1630 if (LHSKnownNegative)
1631 return getFalse(ITy);
1632 if (LHSKnownNonNegative)
1633 return getTrue(ITy);
1635 case ICmpInst::ICMP_SGT:
1636 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1637 if (LHSKnownNegative)
1638 return getFalse(ITy);
1639 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1640 return getTrue(ITy);
1645 // See if we are doing a comparison with a constant integer.
1646 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1647 // Rule out tautological comparisons (eg., ult 0 or uge 0).
1648 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
1649 if (RHS_CR.isEmptySet())
1650 return ConstantInt::getFalse(CI->getContext());
1651 if (RHS_CR.isFullSet())
1652 return ConstantInt::getTrue(CI->getContext());
1654 // Many binary operators with constant RHS have easy to compute constant
1655 // range. Use them to check whether the comparison is a tautology.
1656 uint32_t Width = CI->getBitWidth();
1657 APInt Lower = APInt(Width, 0);
1658 APInt Upper = APInt(Width, 0);
1660 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
1661 // 'urem x, CI2' produces [0, CI2).
1662 Upper = CI2->getValue();
1663 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
1664 // 'srem x, CI2' produces (-|CI2|, |CI2|).
1665 Upper = CI2->getValue().abs();
1666 Lower = (-Upper) + 1;
1667 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
1668 // 'udiv CI2, x' produces [0, CI2].
1669 Upper = CI2->getValue() + 1;
1670 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
1671 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
1672 APInt NegOne = APInt::getAllOnesValue(Width);
1674 Upper = NegOne.udiv(CI2->getValue()) + 1;
1675 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
1676 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
1677 APInt IntMin = APInt::getSignedMinValue(Width);
1678 APInt IntMax = APInt::getSignedMaxValue(Width);
1679 APInt Val = CI2->getValue().abs();
1680 if (!Val.isMinValue()) {
1681 Lower = IntMin.sdiv(Val);
1682 Upper = IntMax.sdiv(Val) + 1;
1684 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
1685 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
1686 APInt NegOne = APInt::getAllOnesValue(Width);
1687 if (CI2->getValue().ult(Width))
1688 Upper = NegOne.lshr(CI2->getValue()) + 1;
1689 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
1690 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
1691 APInt IntMin = APInt::getSignedMinValue(Width);
1692 APInt IntMax = APInt::getSignedMaxValue(Width);
1693 if (CI2->getValue().ult(Width)) {
1694 Lower = IntMin.ashr(CI2->getValue());
1695 Upper = IntMax.ashr(CI2->getValue()) + 1;
1697 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
1698 // 'or x, CI2' produces [CI2, UINT_MAX].
1699 Lower = CI2->getValue();
1700 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
1701 // 'and x, CI2' produces [0, CI2].
1702 Upper = CI2->getValue() + 1;
1704 if (Lower != Upper) {
1705 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
1706 if (RHS_CR.contains(LHS_CR))
1707 return ConstantInt::getTrue(RHS->getContext());
1708 if (RHS_CR.inverse().contains(LHS_CR))
1709 return ConstantInt::getFalse(RHS->getContext());
1713 // Compare of cast, for example (zext X) != 0 -> X != 0
1714 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1715 Instruction *LI = cast<CastInst>(LHS);
1716 Value *SrcOp = LI->getOperand(0);
1717 Type *SrcTy = SrcOp->getType();
1718 Type *DstTy = LI->getType();
1720 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1721 // if the integer type is the same size as the pointer type.
1722 if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
1723 TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1724 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1725 // Transfer the cast to the constant.
1726 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1727 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1728 TD, TLI, DT, MaxRecurse-1))
1730 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1731 if (RI->getOperand(0)->getType() == SrcTy)
1732 // Compare without the cast.
1733 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1734 TD, TLI, DT, MaxRecurse-1))
1739 if (isa<ZExtInst>(LHS)) {
1740 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1742 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1743 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1744 // Compare X and Y. Note that signed predicates become unsigned.
1745 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1746 SrcOp, RI->getOperand(0), TD, TLI, DT,
1750 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1751 // too. If not, then try to deduce the result of the comparison.
1752 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1753 // Compute the constant that would happen if we truncated to SrcTy then
1754 // reextended to DstTy.
1755 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1756 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1758 // If the re-extended constant didn't change then this is effectively
1759 // also a case of comparing two zero-extended values.
1760 if (RExt == CI && MaxRecurse)
1761 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1762 SrcOp, Trunc, TD, TLI, DT, MaxRecurse-1))
1765 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1766 // there. Use this to work out the result of the comparison.
1770 assert(false && "Unknown ICmp predicate!");
1772 case ICmpInst::ICMP_EQ:
1773 case ICmpInst::ICMP_UGT:
1774 case ICmpInst::ICMP_UGE:
1775 return ConstantInt::getFalse(CI->getContext());
1777 case ICmpInst::ICMP_NE:
1778 case ICmpInst::ICMP_ULT:
1779 case ICmpInst::ICMP_ULE:
1780 return ConstantInt::getTrue(CI->getContext());
1782 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1783 // is non-negative then LHS <s RHS.
1784 case ICmpInst::ICMP_SGT:
1785 case ICmpInst::ICMP_SGE:
1786 return CI->getValue().isNegative() ?
1787 ConstantInt::getTrue(CI->getContext()) :
1788 ConstantInt::getFalse(CI->getContext());
1790 case ICmpInst::ICMP_SLT:
1791 case ICmpInst::ICMP_SLE:
1792 return CI->getValue().isNegative() ?
1793 ConstantInt::getFalse(CI->getContext()) :
1794 ConstantInt::getTrue(CI->getContext());
1800 if (isa<SExtInst>(LHS)) {
1801 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1803 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1804 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1805 // Compare X and Y. Note that the predicate does not change.
1806 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1807 TD, TLI, DT, MaxRecurse-1))
1810 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1811 // too. If not, then try to deduce the result of the comparison.
1812 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1813 // Compute the constant that would happen if we truncated to SrcTy then
1814 // reextended to DstTy.
1815 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1816 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1818 // If the re-extended constant didn't change then this is effectively
1819 // also a case of comparing two sign-extended values.
1820 if (RExt == CI && MaxRecurse)
1821 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, TLI, DT,
1825 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1826 // bits there. Use this to work out the result of the comparison.
1830 assert(false && "Unknown ICmp predicate!");
1831 case ICmpInst::ICMP_EQ:
1832 return ConstantInt::getFalse(CI->getContext());
1833 case ICmpInst::ICMP_NE:
1834 return ConstantInt::getTrue(CI->getContext());
1836 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1838 case ICmpInst::ICMP_SGT:
1839 case ICmpInst::ICMP_SGE:
1840 return CI->getValue().isNegative() ?
1841 ConstantInt::getTrue(CI->getContext()) :
1842 ConstantInt::getFalse(CI->getContext());
1843 case ICmpInst::ICMP_SLT:
1844 case ICmpInst::ICMP_SLE:
1845 return CI->getValue().isNegative() ?
1846 ConstantInt::getFalse(CI->getContext()) :
1847 ConstantInt::getTrue(CI->getContext());
1849 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
1851 case ICmpInst::ICMP_UGT:
1852 case ICmpInst::ICMP_UGE:
1853 // Comparison is true iff the LHS <s 0.
1855 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
1856 Constant::getNullValue(SrcTy),
1857 TD, TLI, DT, MaxRecurse-1))
1860 case ICmpInst::ICMP_ULT:
1861 case ICmpInst::ICMP_ULE:
1862 // Comparison is true iff the LHS >=s 0.
1864 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
1865 Constant::getNullValue(SrcTy),
1866 TD, TLI, DT, MaxRecurse-1))
1875 // Special logic for binary operators.
1876 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
1877 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
1878 if (MaxRecurse && (LBO || RBO)) {
1879 // Analyze the case when either LHS or RHS is an add instruction.
1880 Value *A = 0, *B = 0, *C = 0, *D = 0;
1881 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
1882 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
1883 if (LBO && LBO->getOpcode() == Instruction::Add) {
1884 A = LBO->getOperand(0); B = LBO->getOperand(1);
1885 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
1886 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
1887 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
1889 if (RBO && RBO->getOpcode() == Instruction::Add) {
1890 C = RBO->getOperand(0); D = RBO->getOperand(1);
1891 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
1892 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
1893 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
1896 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
1897 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
1898 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
1899 Constant::getNullValue(RHS->getType()),
1900 TD, TLI, DT, MaxRecurse-1))
1903 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
1904 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
1905 if (Value *V = SimplifyICmpInst(Pred,
1906 Constant::getNullValue(LHS->getType()),
1907 C == LHS ? D : C, TD, TLI, DT, MaxRecurse-1))
1910 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
1911 if (A && C && (A == C || A == D || B == C || B == D) &&
1912 NoLHSWrapProblem && NoRHSWrapProblem) {
1913 // Determine Y and Z in the form icmp (X+Y), (X+Z).
1914 Value *Y = (A == C || A == D) ? B : A;
1915 Value *Z = (C == A || C == B) ? D : C;
1916 if (Value *V = SimplifyICmpInst(Pred, Y, Z, TD, TLI, DT, MaxRecurse-1))
1921 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
1922 bool KnownNonNegative, KnownNegative;
1926 case ICmpInst::ICMP_SGT:
1927 case ICmpInst::ICMP_SGE:
1928 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD);
1929 if (!KnownNonNegative)
1932 case ICmpInst::ICMP_EQ:
1933 case ICmpInst::ICMP_UGT:
1934 case ICmpInst::ICMP_UGE:
1935 return getFalse(ITy);
1936 case ICmpInst::ICMP_SLT:
1937 case ICmpInst::ICMP_SLE:
1938 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD);
1939 if (!KnownNonNegative)
1942 case ICmpInst::ICMP_NE:
1943 case ICmpInst::ICMP_ULT:
1944 case ICmpInst::ICMP_ULE:
1945 return getTrue(ITy);
1948 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
1949 bool KnownNonNegative, KnownNegative;
1953 case ICmpInst::ICMP_SGT:
1954 case ICmpInst::ICMP_SGE:
1955 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD);
1956 if (!KnownNonNegative)
1959 case ICmpInst::ICMP_NE:
1960 case ICmpInst::ICMP_UGT:
1961 case ICmpInst::ICMP_UGE:
1962 return getTrue(ITy);
1963 case ICmpInst::ICMP_SLT:
1964 case ICmpInst::ICMP_SLE:
1965 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD);
1966 if (!KnownNonNegative)
1969 case ICmpInst::ICMP_EQ:
1970 case ICmpInst::ICMP_ULT:
1971 case ICmpInst::ICMP_ULE:
1972 return getFalse(ITy);
1977 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
1978 // icmp pred (X /u Y), X
1979 if (Pred == ICmpInst::ICMP_UGT)
1980 return getFalse(ITy);
1981 if (Pred == ICmpInst::ICMP_ULE)
1982 return getTrue(ITy);
1985 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
1986 LBO->getOperand(1) == RBO->getOperand(1)) {
1987 switch (LBO->getOpcode()) {
1989 case Instruction::UDiv:
1990 case Instruction::LShr:
1991 if (ICmpInst::isSigned(Pred))
1994 case Instruction::SDiv:
1995 case Instruction::AShr:
1996 if (!LBO->isExact() || !RBO->isExact())
1998 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
1999 RBO->getOperand(0), TD, TLI, DT, MaxRecurse-1))
2002 case Instruction::Shl: {
2003 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2004 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2007 if (!NSW && ICmpInst::isSigned(Pred))
2009 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2010 RBO->getOperand(0), TD, TLI, DT, MaxRecurse-1))
2017 // Simplify comparisons involving max/min.
2019 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2020 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2022 // Signed variants on "max(a,b)>=a -> true".
2023 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2024 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2025 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2026 // We analyze this as smax(A, B) pred A.
2028 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2029 (A == LHS || B == LHS)) {
2030 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2031 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2032 // We analyze this as smax(A, B) swapped-pred A.
2033 P = CmpInst::getSwappedPredicate(Pred);
2034 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2035 (A == RHS || B == RHS)) {
2036 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2037 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2038 // We analyze this as smax(-A, -B) swapped-pred -A.
2039 // Note that we do not need to actually form -A or -B thanks to EqP.
2040 P = CmpInst::getSwappedPredicate(Pred);
2041 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2042 (A == LHS || B == LHS)) {
2043 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2044 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2045 // We analyze this as smax(-A, -B) pred -A.
2046 // Note that we do not need to actually form -A or -B thanks to EqP.
2049 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2050 // Cases correspond to "max(A, B) p A".
2054 case CmpInst::ICMP_EQ:
2055 case CmpInst::ICMP_SLE:
2056 // Equivalent to "A EqP B". This may be the same as the condition tested
2057 // in the max/min; if so, we can just return that.
2058 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2060 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2062 // Otherwise, see if "A EqP B" simplifies.
2064 if (Value *V = SimplifyICmpInst(EqP, A, B, TD, TLI, DT, MaxRecurse-1))
2067 case CmpInst::ICMP_NE:
2068 case CmpInst::ICMP_SGT: {
2069 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2070 // Equivalent to "A InvEqP B". This may be the same as the condition
2071 // tested in the max/min; if so, we can just return that.
2072 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2074 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2076 // Otherwise, see if "A InvEqP B" simplifies.
2078 if (Value *V = SimplifyICmpInst(InvEqP, A, B, TD, TLI, DT, MaxRecurse-1))
2082 case CmpInst::ICMP_SGE:
2084 return getTrue(ITy);
2085 case CmpInst::ICMP_SLT:
2087 return getFalse(ITy);
2091 // Unsigned variants on "max(a,b)>=a -> true".
2092 P = CmpInst::BAD_ICMP_PREDICATE;
2093 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2094 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2095 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2096 // We analyze this as umax(A, B) pred A.
2098 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2099 (A == LHS || B == LHS)) {
2100 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2101 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2102 // We analyze this as umax(A, B) swapped-pred A.
2103 P = CmpInst::getSwappedPredicate(Pred);
2104 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2105 (A == RHS || B == RHS)) {
2106 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2107 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2108 // We analyze this as umax(-A, -B) swapped-pred -A.
2109 // Note that we do not need to actually form -A or -B thanks to EqP.
2110 P = CmpInst::getSwappedPredicate(Pred);
2111 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2112 (A == LHS || B == LHS)) {
2113 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2114 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2115 // We analyze this as umax(-A, -B) pred -A.
2116 // Note that we do not need to actually form -A or -B thanks to EqP.
2119 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2120 // Cases correspond to "max(A, B) p A".
2124 case CmpInst::ICMP_EQ:
2125 case CmpInst::ICMP_ULE:
2126 // Equivalent to "A EqP B". This may be the same as the condition tested
2127 // in the max/min; if so, we can just return that.
2128 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2130 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2132 // Otherwise, see if "A EqP B" simplifies.
2134 if (Value *V = SimplifyICmpInst(EqP, A, B, TD, TLI, DT, MaxRecurse-1))
2137 case CmpInst::ICMP_NE:
2138 case CmpInst::ICMP_UGT: {
2139 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2140 // Equivalent to "A InvEqP B". This may be the same as the condition
2141 // tested in the max/min; if so, we can just return that.
2142 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2144 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2146 // Otherwise, see if "A InvEqP B" simplifies.
2148 if (Value *V = SimplifyICmpInst(InvEqP, A, B, TD, TLI, DT, MaxRecurse-1))
2152 case CmpInst::ICMP_UGE:
2154 return getTrue(ITy);
2155 case CmpInst::ICMP_ULT:
2157 return getFalse(ITy);
2161 // Variants on "max(x,y) >= min(x,z)".
2163 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2164 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2165 (A == C || A == D || B == C || B == D)) {
2166 // max(x, ?) pred min(x, ?).
2167 if (Pred == CmpInst::ICMP_SGE)
2169 return getTrue(ITy);
2170 if (Pred == CmpInst::ICMP_SLT)
2172 return getFalse(ITy);
2173 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2174 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2175 (A == C || A == D || B == C || B == D)) {
2176 // min(x, ?) pred max(x, ?).
2177 if (Pred == CmpInst::ICMP_SLE)
2179 return getTrue(ITy);
2180 if (Pred == CmpInst::ICMP_SGT)
2182 return getFalse(ITy);
2183 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2184 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2185 (A == C || A == D || B == C || B == D)) {
2186 // max(x, ?) pred min(x, ?).
2187 if (Pred == CmpInst::ICMP_UGE)
2189 return getTrue(ITy);
2190 if (Pred == CmpInst::ICMP_ULT)
2192 return getFalse(ITy);
2193 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2194 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2195 (A == C || A == D || B == C || B == D)) {
2196 // min(x, ?) pred max(x, ?).
2197 if (Pred == CmpInst::ICMP_ULE)
2199 return getTrue(ITy);
2200 if (Pred == CmpInst::ICMP_UGT)
2202 return getFalse(ITy);
2205 // If the comparison is with the result of a select instruction, check whether
2206 // comparing with either branch of the select always yields the same value.
2207 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2208 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2211 // If the comparison is with the result of a phi instruction, check whether
2212 // doing the compare with each incoming phi value yields a common result.
2213 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2214 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2220 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2221 const TargetData *TD,
2222 const TargetLibraryInfo *TLI,
2223 const DominatorTree *DT) {
2224 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2227 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
2228 /// fold the result. If not, this returns null.
2229 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2230 const TargetData *TD,
2231 const TargetLibraryInfo *TLI,
2232 const DominatorTree *DT,
2233 unsigned MaxRecurse) {
2234 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2235 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
2237 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2238 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2239 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD, TLI);
2241 // If we have a constant, make sure it is on the RHS.
2242 std::swap(LHS, RHS);
2243 Pred = CmpInst::getSwappedPredicate(Pred);
2246 // Fold trivial predicates.
2247 if (Pred == FCmpInst::FCMP_FALSE)
2248 return ConstantInt::get(GetCompareTy(LHS), 0);
2249 if (Pred == FCmpInst::FCMP_TRUE)
2250 return ConstantInt::get(GetCompareTy(LHS), 1);
2252 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
2253 return UndefValue::get(GetCompareTy(LHS));
2255 // fcmp x,x -> true/false. Not all compares are foldable.
2257 if (CmpInst::isTrueWhenEqual(Pred))
2258 return ConstantInt::get(GetCompareTy(LHS), 1);
2259 if (CmpInst::isFalseWhenEqual(Pred))
2260 return ConstantInt::get(GetCompareTy(LHS), 0);
2263 // Handle fcmp with constant RHS
2264 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2265 // If the constant is a nan, see if we can fold the comparison based on it.
2266 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2267 if (CFP->getValueAPF().isNaN()) {
2268 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
2269 return ConstantInt::getFalse(CFP->getContext());
2270 assert(FCmpInst::isUnordered(Pred) &&
2271 "Comparison must be either ordered or unordered!");
2272 // True if unordered.
2273 return ConstantInt::getTrue(CFP->getContext());
2275 // Check whether the constant is an infinity.
2276 if (CFP->getValueAPF().isInfinity()) {
2277 if (CFP->getValueAPF().isNegative()) {
2279 case FCmpInst::FCMP_OLT:
2280 // No value is ordered and less than negative infinity.
2281 return ConstantInt::getFalse(CFP->getContext());
2282 case FCmpInst::FCMP_UGE:
2283 // All values are unordered with or at least negative infinity.
2284 return ConstantInt::getTrue(CFP->getContext());
2290 case FCmpInst::FCMP_OGT:
2291 // No value is ordered and greater than infinity.
2292 return ConstantInt::getFalse(CFP->getContext());
2293 case FCmpInst::FCMP_ULE:
2294 // All values are unordered with and at most infinity.
2295 return ConstantInt::getTrue(CFP->getContext());
2304 // If the comparison is with the result of a select instruction, check whether
2305 // comparing with either branch of the select always yields the same value.
2306 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2307 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2310 // If the comparison is with the result of a phi instruction, check whether
2311 // doing the compare with each incoming phi value yields a common result.
2312 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2313 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2319 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2320 const TargetData *TD,
2321 const TargetLibraryInfo *TLI,
2322 const DominatorTree *DT) {
2323 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2326 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
2327 /// the result. If not, this returns null.
2328 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
2329 const TargetData *TD, const DominatorTree *) {
2330 // select true, X, Y -> X
2331 // select false, X, Y -> Y
2332 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
2333 return CB->getZExtValue() ? TrueVal : FalseVal;
2335 // select C, X, X -> X
2336 if (TrueVal == FalseVal)
2339 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
2340 if (isa<Constant>(TrueVal))
2344 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
2346 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
2352 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
2353 /// fold the result. If not, this returns null.
2354 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const TargetData *TD,
2355 const DominatorTree *) {
2356 // The type of the GEP pointer operand.
2357 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType());
2358 // The GEP pointer operand is not a pointer, it's a vector of pointers.
2362 // getelementptr P -> P.
2363 if (Ops.size() == 1)
2366 if (isa<UndefValue>(Ops[0])) {
2367 // Compute the (pointer) type returned by the GEP instruction.
2368 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
2369 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
2370 return UndefValue::get(GEPTy);
2373 if (Ops.size() == 2) {
2374 // getelementptr P, 0 -> P.
2375 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
2378 // getelementptr P, N -> P if P points to a type of zero size.
2380 Type *Ty = PtrTy->getElementType();
2381 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
2386 // Check to see if this is constant foldable.
2387 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2388 if (!isa<Constant>(Ops[i]))
2391 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
2394 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
2395 /// can fold the result. If not, this returns null.
2396 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
2397 ArrayRef<unsigned> Idxs,
2399 const DominatorTree *) {
2400 if (Constant *CAgg = dyn_cast<Constant>(Agg))
2401 if (Constant *CVal = dyn_cast<Constant>(Val))
2402 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
2404 // insertvalue x, undef, n -> x
2405 if (match(Val, m_Undef()))
2408 // insertvalue x, (extractvalue y, n), n
2409 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
2410 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
2411 EV->getIndices() == Idxs) {
2412 // insertvalue undef, (extractvalue y, n), n -> y
2413 if (match(Agg, m_Undef()))
2414 return EV->getAggregateOperand();
2416 // insertvalue y, (extractvalue y, n), n -> y
2417 if (Agg == EV->getAggregateOperand())
2424 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
2425 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
2426 // If all of the PHI's incoming values are the same then replace the PHI node
2427 // with the common value.
2428 Value *CommonValue = 0;
2429 bool HasUndefInput = false;
2430 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
2431 Value *Incoming = PN->getIncomingValue(i);
2432 // If the incoming value is the phi node itself, it can safely be skipped.
2433 if (Incoming == PN) continue;
2434 if (isa<UndefValue>(Incoming)) {
2435 // Remember that we saw an undef value, but otherwise ignore them.
2436 HasUndefInput = true;
2439 if (CommonValue && Incoming != CommonValue)
2440 return 0; // Not the same, bail out.
2441 CommonValue = Incoming;
2444 // If CommonValue is null then all of the incoming values were either undef or
2445 // equal to the phi node itself.
2447 return UndefValue::get(PN->getType());
2449 // If we have a PHI node like phi(X, undef, X), where X is defined by some
2450 // instruction, we cannot return X as the result of the PHI node unless it
2451 // dominates the PHI block.
2453 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
2458 //=== Helper functions for higher up the class hierarchy.
2460 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
2461 /// fold the result. If not, this returns null.
2462 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2463 const TargetData *TD,
2464 const TargetLibraryInfo *TLI,
2465 const DominatorTree *DT,
2466 unsigned MaxRecurse) {
2468 case Instruction::Add:
2469 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2470 TD, TLI, DT, MaxRecurse);
2471 case Instruction::Sub:
2472 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2473 TD, TLI, DT, MaxRecurse);
2474 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, TD, TLI, DT,
2476 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, TLI, DT,
2478 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, TLI, DT,
2480 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, TLI, DT,
2482 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, TD, TLI, DT,
2484 case Instruction::URem: return SimplifyURemInst(LHS, RHS, TD, TLI, DT,
2486 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, TD, TLI, DT,
2488 case Instruction::Shl:
2489 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2490 TD, TLI, DT, MaxRecurse);
2491 case Instruction::LShr:
2492 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, TD, TLI, DT,
2494 case Instruction::AShr:
2495 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, TD, TLI, DT,
2497 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, TLI, DT,
2499 case Instruction::Or: return SimplifyOrInst (LHS, RHS, TD, TLI, DT,
2501 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, TLI, DT,
2504 if (Constant *CLHS = dyn_cast<Constant>(LHS))
2505 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
2506 Constant *COps[] = {CLHS, CRHS};
2507 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, TD, TLI);
2510 // If the operation is associative, try some generic simplifications.
2511 if (Instruction::isAssociative(Opcode))
2512 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, TLI, DT,
2516 // If the operation is with the result of a select instruction, check whether
2517 // operating on either branch of the select always yields the same value.
2518 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2519 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, TLI, DT,
2523 // If the operation is with the result of a phi instruction, check whether
2524 // operating on all incoming values of the phi always yields the same value.
2525 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2526 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, TLI, DT,
2534 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2535 const TargetData *TD, const TargetLibraryInfo *TLI,
2536 const DominatorTree *DT) {
2537 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, TLI, DT, RecursionLimit);
2540 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
2541 /// fold the result.
2542 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2543 const TargetData *TD,
2544 const TargetLibraryInfo *TLI,
2545 const DominatorTree *DT,
2546 unsigned MaxRecurse) {
2547 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
2548 return SimplifyICmpInst(Predicate, LHS, RHS, TD, TLI, DT, MaxRecurse);
2549 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, TLI, DT, MaxRecurse);
2552 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2553 const TargetData *TD, const TargetLibraryInfo *TLI,
2554 const DominatorTree *DT) {
2555 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2558 static Value *SimplifyCallInst(CallInst *CI) {
2559 // call undef -> undef
2560 if (isa<UndefValue>(CI->getCalledValue()))
2561 return UndefValue::get(CI->getType());
2566 /// SimplifyInstruction - See if we can compute a simplified version of this
2567 /// instruction. If not, this returns null.
2568 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
2569 const TargetLibraryInfo *TLI,
2570 const DominatorTree *DT) {
2573 switch (I->getOpcode()) {
2575 Result = ConstantFoldInstruction(I, TD, TLI);
2577 case Instruction::Add:
2578 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
2579 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2580 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2583 case Instruction::Sub:
2584 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
2585 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2586 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2589 case Instruction::Mul:
2590 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2592 case Instruction::SDiv:
2593 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2595 case Instruction::UDiv:
2596 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2598 case Instruction::FDiv:
2599 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2601 case Instruction::SRem:
2602 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2604 case Instruction::URem:
2605 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2607 case Instruction::FRem:
2608 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2610 case Instruction::Shl:
2611 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
2612 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2613 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2616 case Instruction::LShr:
2617 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
2618 cast<BinaryOperator>(I)->isExact(),
2621 case Instruction::AShr:
2622 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
2623 cast<BinaryOperator>(I)->isExact(),
2626 case Instruction::And:
2627 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2629 case Instruction::Or:
2630 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2632 case Instruction::Xor:
2633 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2635 case Instruction::ICmp:
2636 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
2637 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2639 case Instruction::FCmp:
2640 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
2641 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2643 case Instruction::Select:
2644 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
2645 I->getOperand(2), TD, DT);
2647 case Instruction::GetElementPtr: {
2648 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
2649 Result = SimplifyGEPInst(Ops, TD, DT);
2652 case Instruction::InsertValue: {
2653 InsertValueInst *IV = cast<InsertValueInst>(I);
2654 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
2655 IV->getInsertedValueOperand(),
2656 IV->getIndices(), TD, DT);
2659 case Instruction::PHI:
2660 Result = SimplifyPHINode(cast<PHINode>(I), DT);
2662 case Instruction::Call:
2663 Result = SimplifyCallInst(cast<CallInst>(I));
2667 /// If called on unreachable code, the above logic may report that the
2668 /// instruction simplified to itself. Make life easier for users by
2669 /// detecting that case here, returning a safe value instead.
2670 return Result == I ? UndefValue::get(I->getType()) : Result;
2673 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
2674 /// delete the From instruction. In addition to a basic RAUW, this does a
2675 /// recursive simplification of the newly formed instructions. This catches
2676 /// things where one simplification exposes other opportunities. This only
2677 /// simplifies and deletes scalar operations, it does not change the CFG.
2679 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
2680 const TargetData *TD,
2681 const TargetLibraryInfo *TLI,
2682 const DominatorTree *DT) {
2683 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
2685 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
2686 // we can know if it gets deleted out from under us or replaced in a
2687 // recursive simplification.
2688 WeakVH FromHandle(From);
2689 WeakVH ToHandle(To);
2691 while (!From->use_empty()) {
2692 // Update the instruction to use the new value.
2693 Use &TheUse = From->use_begin().getUse();
2694 Instruction *User = cast<Instruction>(TheUse.getUser());
2697 // Check to see if the instruction can be folded due to the operand
2698 // replacement. For example changing (or X, Y) into (or X, -1) can replace
2699 // the 'or' with -1.
2700 Value *SimplifiedVal;
2702 // Sanity check to make sure 'User' doesn't dangle across
2703 // SimplifyInstruction.
2704 AssertingVH<> UserHandle(User);
2706 SimplifiedVal = SimplifyInstruction(User, TD, TLI, DT);
2707 if (SimplifiedVal == 0) continue;
2710 // Recursively simplify this user to the new value.
2711 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, TLI, DT);
2712 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
2715 assert(ToHandle && "To value deleted by recursive simplification?");
2717 // If the recursive simplification ended up revisiting and deleting
2718 // 'From' then we're done.
2723 // If 'From' has value handles referring to it, do a real RAUW to update them.
2724 From->replaceAllUsesWith(To);
2726 From->eraseFromParent();