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");
43 static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
44 const TargetLibraryInfo *, const DominatorTree *,
46 static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
47 const TargetLibraryInfo *, const DominatorTree *,
49 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
50 const TargetLibraryInfo *, const DominatorTree *,
52 static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
53 const TargetLibraryInfo *, const DominatorTree *,
55 static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
56 const TargetLibraryInfo *, const DominatorTree *,
59 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
60 /// a vector with every element false, as appropriate for the type.
61 static Constant *getFalse(Type *Ty) {
62 assert(Ty->getScalarType()->isIntegerTy(1) &&
63 "Expected i1 type or a vector of i1!");
64 return Constant::getNullValue(Ty);
67 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
68 /// a vector with every element true, as appropriate for the type.
69 static Constant *getTrue(Type *Ty) {
70 assert(Ty->getScalarType()->isIntegerTy(1) &&
71 "Expected i1 type or a vector of i1!");
72 return Constant::getAllOnesValue(Ty);
75 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
76 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
78 CmpInst *Cmp = dyn_cast<CmpInst>(V);
81 CmpInst::Predicate CPred = Cmp->getPredicate();
82 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
83 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
85 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
89 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
90 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
91 Instruction *I = dyn_cast<Instruction>(V);
93 // Arguments and constants dominate all instructions.
96 // If we have a DominatorTree then do a precise test.
98 return !DT->isReachableFromEntry(P->getParent()) ||
99 !DT->isReachableFromEntry(I->getParent()) || DT->dominates(I, P);
101 // Otherwise, if the instruction is in the entry block, and is not an invoke,
102 // then it obviously dominates all phi nodes.
103 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
110 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
111 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
112 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
113 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
114 /// Returns the simplified value, or null if no simplification was performed.
115 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
116 unsigned OpcToExpand, const TargetData *TD,
117 const TargetLibraryInfo *TLI, const DominatorTree *DT,
118 unsigned MaxRecurse) {
119 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
120 // Recursion is always used, so bail out at once if we already hit the limit.
124 // Check whether the expression has the form "(A op' B) op C".
125 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
126 if (Op0->getOpcode() == OpcodeToExpand) {
127 // It does! Try turning it into "(A op C) op' (B op C)".
128 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
129 // Do "A op C" and "B op C" both simplify?
130 if (Value *L = SimplifyBinOp(Opcode, A, C, TD, TLI, DT, MaxRecurse))
131 if (Value *R = SimplifyBinOp(Opcode, B, C, TD, TLI, DT, MaxRecurse)) {
132 // They do! Return "L op' R" if it simplifies or is already available.
133 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
134 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
135 && L == B && R == A)) {
139 // Otherwise return "L op' R" if it simplifies.
140 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, TLI, DT,
148 // Check whether the expression has the form "A op (B op' C)".
149 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
150 if (Op1->getOpcode() == OpcodeToExpand) {
151 // It does! Try turning it into "(A op B) op' (A op C)".
152 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
153 // Do "A op B" and "A op C" both simplify?
154 if (Value *L = SimplifyBinOp(Opcode, A, B, TD, TLI, DT, MaxRecurse))
155 if (Value *R = SimplifyBinOp(Opcode, A, C, TD, TLI, DT, MaxRecurse)) {
156 // They do! Return "L op' R" if it simplifies or is already available.
157 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
158 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
159 && L == C && R == B)) {
163 // Otherwise return "L op' R" if it simplifies.
164 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, TLI, DT,
175 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
176 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
177 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
178 /// Returns the simplified value, or null if no simplification was performed.
179 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
180 unsigned OpcToExtract, const TargetData *TD,
181 const TargetLibraryInfo *TLI,
182 const DominatorTree *DT,
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, TD, TLI, DT, 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, TD, TLI, DT,
224 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
225 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
226 // commutative case, "(A op' B) op (B op' D)"?
227 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
228 Value *CC = B == D ? C : D;
229 // Form "(A op CC) op' B" if it simplifies completely..
230 // Does "A op CC" simplify?
231 if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, TLI, DT, MaxRecurse)) {
232 // It does! Return "V op' B" if it simplifies or is already available.
233 // If V equals A then "V op' B" is just the LHS. If V equals CC then
234 // "V op' B" is just the RHS.
235 if (V == A || V == CC) {
237 return V == A ? LHS : RHS;
239 // Otherwise return "V op' B" if it simplifies.
240 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, TLI, DT,
251 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
252 /// operations. Returns the simpler value, or null if none was found.
253 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
254 const TargetData *TD,
255 const TargetLibraryInfo *TLI,
256 const DominatorTree *DT,
257 unsigned MaxRecurse) {
258 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
259 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
261 // Recursion is always used, so bail out at once if we already hit the limit.
265 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
266 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
268 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
269 if (Op0 && Op0->getOpcode() == Opcode) {
270 Value *A = Op0->getOperand(0);
271 Value *B = Op0->getOperand(1);
274 // Does "B op C" simplify?
275 if (Value *V = SimplifyBinOp(Opcode, B, C, TD, TLI, DT, MaxRecurse)) {
276 // It does! Return "A op V" if it simplifies or is already available.
277 // If V equals B then "A op V" is just the LHS.
278 if (V == B) return LHS;
279 // Otherwise return "A op V" if it simplifies.
280 if (Value *W = SimplifyBinOp(Opcode, A, V, TD, TLI, DT, MaxRecurse)) {
287 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
288 if (Op1 && Op1->getOpcode() == Opcode) {
290 Value *B = Op1->getOperand(0);
291 Value *C = Op1->getOperand(1);
293 // Does "A op B" simplify?
294 if (Value *V = SimplifyBinOp(Opcode, A, B, TD, TLI, DT, MaxRecurse)) {
295 // It does! Return "V op C" if it simplifies or is already available.
296 // If V equals B then "V op C" is just the RHS.
297 if (V == B) return RHS;
298 // Otherwise return "V op C" if it simplifies.
299 if (Value *W = SimplifyBinOp(Opcode, V, C, TD, TLI, DT, MaxRecurse)) {
306 // The remaining transforms require commutativity as well as associativity.
307 if (!Instruction::isCommutative(Opcode))
310 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
311 if (Op0 && Op0->getOpcode() == Opcode) {
312 Value *A = Op0->getOperand(0);
313 Value *B = Op0->getOperand(1);
316 // Does "C op A" simplify?
317 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, TLI, DT, MaxRecurse)) {
318 // It does! Return "V op B" if it simplifies or is already available.
319 // If V equals A then "V op B" is just the LHS.
320 if (V == A) return LHS;
321 // Otherwise return "V op B" if it simplifies.
322 if (Value *W = SimplifyBinOp(Opcode, V, B, TD, TLI, DT, MaxRecurse)) {
329 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
330 if (Op1 && Op1->getOpcode() == Opcode) {
332 Value *B = Op1->getOperand(0);
333 Value *C = Op1->getOperand(1);
335 // Does "C op A" simplify?
336 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, TLI, DT, MaxRecurse)) {
337 // It does! Return "B op V" if it simplifies or is already available.
338 // If V equals C then "B op V" is just the RHS.
339 if (V == C) return RHS;
340 // Otherwise return "B op V" if it simplifies.
341 if (Value *W = SimplifyBinOp(Opcode, B, V, TD, TLI, DT, MaxRecurse)) {
351 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
352 /// instruction as an operand, try to simplify the binop by seeing whether
353 /// evaluating it on both branches of the select results in the same value.
354 /// Returns the common value if so, otherwise returns null.
355 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
356 const TargetData *TD,
357 const TargetLibraryInfo *TLI,
358 const DominatorTree *DT,
359 unsigned MaxRecurse) {
360 // Recursion is always used, so bail out at once if we already hit the limit.
365 if (isa<SelectInst>(LHS)) {
366 SI = cast<SelectInst>(LHS);
368 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
369 SI = cast<SelectInst>(RHS);
372 // Evaluate the BinOp on the true and false branches of the select.
376 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, TLI, DT, MaxRecurse);
377 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, TLI, DT, MaxRecurse);
379 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, TLI, DT, MaxRecurse);
380 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, TLI, DT, MaxRecurse);
383 // If they simplified to the same value, then return the common value.
384 // If they both failed to simplify then return null.
388 // If one branch simplified to undef, return the other one.
389 if (TV && isa<UndefValue>(TV))
391 if (FV && isa<UndefValue>(FV))
394 // If applying the operation did not change the true and false select values,
395 // then the result of the binop is the select itself.
396 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
399 // If one branch simplified and the other did not, and the simplified
400 // value is equal to the unsimplified one, return the simplified value.
401 // For example, select (cond, X, X & Z) & Z -> X & Z.
402 if ((FV && !TV) || (TV && !FV)) {
403 // Check that the simplified value has the form "X op Y" where "op" is the
404 // same as the original operation.
405 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
406 if (Simplified && Simplified->getOpcode() == Opcode) {
407 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
408 // We already know that "op" is the same as for the simplified value. See
409 // if the operands match too. If so, return the simplified value.
410 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
411 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
412 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
413 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
414 Simplified->getOperand(1) == UnsimplifiedRHS)
416 if (Simplified->isCommutative() &&
417 Simplified->getOperand(1) == UnsimplifiedLHS &&
418 Simplified->getOperand(0) == UnsimplifiedRHS)
426 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
427 /// try to simplify the comparison by seeing whether both branches of the select
428 /// result in the same value. Returns the common value if so, otherwise returns
430 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
431 Value *RHS, const TargetData *TD,
432 const TargetLibraryInfo *TLI,
433 const DominatorTree *DT,
434 unsigned MaxRecurse) {
435 // Recursion is always used, so bail out at once if we already hit the limit.
439 // Make sure the select is on the LHS.
440 if (!isa<SelectInst>(LHS)) {
442 Pred = CmpInst::getSwappedPredicate(Pred);
444 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
445 SelectInst *SI = cast<SelectInst>(LHS);
446 Value *Cond = SI->getCondition();
447 Value *TV = SI->getTrueValue();
448 Value *FV = SI->getFalseValue();
450 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
451 // Does "cmp TV, RHS" simplify?
452 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, TD, TLI, DT, MaxRecurse);
454 // It not only simplified, it simplified to the select condition. Replace
456 TCmp = getTrue(Cond->getType());
458 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
459 // condition then we can replace it with 'true'. Otherwise give up.
460 if (!isSameCompare(Cond, Pred, TV, RHS))
462 TCmp = getTrue(Cond->getType());
465 // Does "cmp FV, RHS" simplify?
466 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, TD, TLI, DT, MaxRecurse);
468 // It not only simplified, it simplified to the select condition. Replace
470 FCmp = getFalse(Cond->getType());
472 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
473 // condition then we can replace it with 'false'. Otherwise give up.
474 if (!isSameCompare(Cond, Pred, FV, RHS))
476 FCmp = getFalse(Cond->getType());
479 // If both sides simplified to the same value, then use it as the result of
480 // the original comparison.
484 // The remaining cases only make sense if the select condition has the same
485 // type as the result of the comparison, so bail out if this is not so.
486 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
488 // If the false value simplified to false, then the result of the compare
489 // is equal to "Cond && TCmp". This also catches the case when the false
490 // value simplified to false and the true value to true, returning "Cond".
491 if (match(FCmp, m_Zero()))
492 if (Value *V = SimplifyAndInst(Cond, TCmp, TD, TLI, DT, MaxRecurse))
494 // If the true value simplified to true, then the result of the compare
495 // is equal to "Cond || FCmp".
496 if (match(TCmp, m_One()))
497 if (Value *V = SimplifyOrInst(Cond, FCmp, TD, TLI, DT, MaxRecurse))
499 // Finally, if the false value simplified to true and the true value to
500 // false, then the result of the compare is equal to "!Cond".
501 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
503 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
504 TD, TLI, DT, MaxRecurse))
510 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
511 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
512 /// it on the incoming phi values yields the same result for every value. If so
513 /// returns the common value, otherwise returns null.
514 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
515 const TargetData *TD,
516 const TargetLibraryInfo *TLI,
517 const DominatorTree *DT,
518 unsigned MaxRecurse) {
519 // Recursion is always used, so bail out at once if we already hit the limit.
524 if (isa<PHINode>(LHS)) {
525 PI = cast<PHINode>(LHS);
526 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
527 if (!ValueDominatesPHI(RHS, PI, DT))
530 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
531 PI = cast<PHINode>(RHS);
532 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
533 if (!ValueDominatesPHI(LHS, PI, DT))
537 // Evaluate the BinOp on the incoming phi values.
538 Value *CommonValue = 0;
539 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
540 Value *Incoming = PI->getIncomingValue(i);
541 // If the incoming value is the phi node itself, it can safely be skipped.
542 if (Incoming == PI) continue;
543 Value *V = PI == LHS ?
544 SimplifyBinOp(Opcode, Incoming, RHS, TD, TLI, DT, MaxRecurse) :
545 SimplifyBinOp(Opcode, LHS, Incoming, TD, TLI, DT, MaxRecurse);
546 // If the operation failed to simplify, or simplified to a different value
547 // to previously, then give up.
548 if (!V || (CommonValue && V != CommonValue))
556 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
557 /// try to simplify the comparison by seeing whether comparing with all of the
558 /// incoming phi values yields the same result every time. If so returns the
559 /// common result, otherwise returns null.
560 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
561 const TargetData *TD,
562 const TargetLibraryInfo *TLI,
563 const DominatorTree *DT,
564 unsigned MaxRecurse) {
565 // Recursion is always used, so bail out at once if we already hit the limit.
569 // Make sure the phi is on the LHS.
570 if (!isa<PHINode>(LHS)) {
572 Pred = CmpInst::getSwappedPredicate(Pred);
574 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
575 PHINode *PI = cast<PHINode>(LHS);
577 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
578 if (!ValueDominatesPHI(RHS, PI, DT))
581 // Evaluate the BinOp on the incoming phi values.
582 Value *CommonValue = 0;
583 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
584 Value *Incoming = PI->getIncomingValue(i);
585 // If the incoming value is the phi node itself, it can safely be skipped.
586 if (Incoming == PI) continue;
587 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, TLI, DT, MaxRecurse);
588 // If the operation failed to simplify, or simplified to a different value
589 // to previously, then give up.
590 if (!V || (CommonValue && V != CommonValue))
598 /// SimplifyAddInst - Given operands for an Add, see if we can
599 /// fold the result. If not, this returns null.
600 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
601 const TargetData *TD,
602 const TargetLibraryInfo *TLI,
603 const DominatorTree *DT,
604 unsigned MaxRecurse) {
605 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
606 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
607 Constant *Ops[] = { CLHS, CRHS };
608 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
612 // Canonicalize the constant to the RHS.
616 // X + undef -> undef
617 if (match(Op1, m_Undef()))
621 if (match(Op1, m_Zero()))
628 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
629 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
632 // X + ~X -> -1 since ~X = -X-1
633 if (match(Op0, m_Not(m_Specific(Op1))) ||
634 match(Op1, m_Not(m_Specific(Op0))))
635 return Constant::getAllOnesValue(Op0->getType());
638 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
639 if (Value *V = SimplifyXorInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
642 // Try some generic simplifications for associative operations.
643 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, TLI, DT,
647 // Mul distributes over Add. Try some generic simplifications based on this.
648 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
649 TD, TLI, DT, MaxRecurse))
652 // Threading Add over selects and phi nodes is pointless, so don't bother.
653 // Threading over the select in "A + select(cond, B, C)" means evaluating
654 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
655 // only if B and C are equal. If B and C are equal then (since we assume
656 // that operands have already been simplified) "select(cond, B, C)" should
657 // have been simplified to the common value of B and C already. Analysing
658 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
659 // for threading over phi nodes.
664 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
665 const TargetData *TD, const TargetLibraryInfo *TLI,
666 const DominatorTree *DT) {
667 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
670 /// \brief Accumulate the constant integer offset a GEP represents.
672 /// Given a getelementptr instruction/constantexpr, accumulate the constant
673 /// offset from the base pointer into the provided APInt 'Offset'. Returns true
674 /// if the GEP has all-constant indices. Returns false if any non-constant
675 /// index is encountered leaving the 'Offset' in an undefined state. The
676 /// 'Offset' APInt must be the bitwidth of the target's pointer size.
677 static bool accumulateGEPOffset(const TargetData &TD, GEPOperator *GEP,
679 unsigned IntPtrWidth = TD.getPointerSizeInBits();
680 assert(IntPtrWidth == Offset.getBitWidth());
682 gep_type_iterator GTI = gep_type_begin(GEP);
683 for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end(); I != E;
685 ConstantInt *OpC = dyn_cast<ConstantInt>(*I);
686 if (!OpC) return false;
687 if (OpC->isZero()) continue;
689 // Handle a struct index, which adds its field offset to the pointer.
690 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
691 unsigned ElementIdx = OpC->getZExtValue();
692 const StructLayout *SL = TD.getStructLayout(STy);
693 Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx),
698 APInt TypeSize(IntPtrWidth, TD.getTypeAllocSize(GTI.getIndexedType()),
700 Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
705 /// \brief Compute the base pointer and cumulative constant offsets for V.
707 /// This strips all constant offsets off of V, leaving it the base pointer, and
708 /// accumulates the total constant offset applied in the returned constant. It
709 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
710 /// no constant offsets applied.
711 static Constant *stripAndComputeConstantOffsets(const TargetData &TD,
713 if (!V->getType()->isPointerTy())
716 unsigned IntPtrWidth = TD.getPointerSizeInBits();
717 APInt Offset = APInt::getNullValue(IntPtrWidth);
719 // Even though we don't look through PHI nodes, we could be called on an
720 // instruction in an unreachable block, which may be on a cycle.
721 SmallPtrSet<Value *, 4> Visited;
724 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
725 if (!accumulateGEPOffset(TD, GEP, Offset))
727 V = GEP->getPointerOperand();
728 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
729 V = cast<Operator>(V)->getOperand(0);
730 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
731 if (GA->mayBeOverridden())
733 V = GA->getAliasee();
737 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
738 } while (Visited.insert(V));
740 Type *IntPtrTy = TD.getIntPtrType(V->getContext());
741 return ConstantInt::get(IntPtrTy, Offset);
744 /// \brief Compute the constant difference between two pointer values.
745 /// If the difference is not a constant, returns zero.
746 static Constant *computePointerDifference(const TargetData &TD,
747 Value *LHS, Value *RHS) {
748 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
751 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
755 // If LHS and RHS are not related via constant offsets to the same base
756 // value, there is nothing we can do here.
760 // Otherwise, the difference of LHS - RHS can be computed as:
762 // = (LHSOffset + Base) - (RHSOffset + Base)
763 // = LHSOffset - RHSOffset
764 return ConstantExpr::getSub(LHSOffset, RHSOffset);
767 /// SimplifySubInst - Given operands for a Sub, see if we can
768 /// fold the result. If not, this returns null.
769 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
770 const TargetData *TD,
771 const TargetLibraryInfo *TLI,
772 const DominatorTree *DT,
773 unsigned MaxRecurse) {
774 if (Constant *CLHS = dyn_cast<Constant>(Op0))
775 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
776 Constant *Ops[] = { CLHS, CRHS };
777 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
781 // X - undef -> undef
782 // undef - X -> undef
783 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
784 return UndefValue::get(Op0->getType());
787 if (match(Op1, m_Zero()))
792 return Constant::getNullValue(Op0->getType());
797 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
798 match(Op0, m_Shl(m_Specific(Op1), m_One())))
802 Value *LHSOp, *RHSOp;
803 if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
804 match(Op1, m_PtrToInt(m_Value(RHSOp))))
805 if (Constant *Result = computePointerDifference(*TD, LHSOp, RHSOp))
806 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
808 // trunc(p)-trunc(q) -> trunc(p-q)
809 if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
810 match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
811 if (Constant *Result = computePointerDifference(*TD, LHSOp, RHSOp))
812 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
815 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
816 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
817 Value *Y = 0, *Z = Op1;
818 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
819 // See if "V === Y - Z" simplifies.
820 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, TLI, DT, MaxRecurse-1))
821 // It does! Now see if "X + V" simplifies.
822 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, TLI, DT,
824 // It does, we successfully reassociated!
828 // See if "V === X - Z" simplifies.
829 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, TLI, DT, MaxRecurse-1))
830 // It does! Now see if "Y + V" simplifies.
831 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, TLI, DT,
833 // It does, we successfully reassociated!
839 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
840 // For example, X - (X + 1) -> -1
842 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
843 // See if "V === X - Y" simplifies.
844 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, TLI, DT, MaxRecurse-1))
845 // It does! Now see if "V - Z" simplifies.
846 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, TLI, DT,
848 // It does, we successfully reassociated!
852 // See if "V === X - Z" simplifies.
853 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, TLI, DT, MaxRecurse-1))
854 // It does! Now see if "V - Y" simplifies.
855 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, TLI, DT,
857 // It does, we successfully reassociated!
863 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
864 // For example, X - (X - Y) -> Y.
866 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
867 // See if "V === Z - X" simplifies.
868 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, TLI, DT, MaxRecurse-1))
869 // It does! Now see if "V + Y" simplifies.
870 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, TLI, DT,
872 // It does, we successfully reassociated!
877 // Mul distributes over Sub. Try some generic simplifications based on this.
878 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
879 TD, TLI, DT, MaxRecurse))
883 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
884 if (Value *V = SimplifyXorInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
887 // Threading Sub over selects and phi nodes is pointless, so don't bother.
888 // Threading over the select in "A - select(cond, B, C)" means evaluating
889 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
890 // only if B and C are equal. If B and C are equal then (since we assume
891 // that operands have already been simplified) "select(cond, B, C)" should
892 // have been simplified to the common value of B and C already. Analysing
893 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
894 // for threading over phi nodes.
899 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
900 const TargetData *TD,
901 const TargetLibraryInfo *TLI,
902 const DominatorTree *DT) {
903 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
906 /// SimplifyMulInst - Given operands for a Mul, see if we can
907 /// fold the result. If not, this returns null.
908 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
909 const TargetLibraryInfo *TLI,
910 const DominatorTree *DT, unsigned MaxRecurse) {
911 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
912 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
913 Constant *Ops[] = { CLHS, CRHS };
914 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
918 // Canonicalize the constant to the RHS.
923 if (match(Op1, m_Undef()))
924 return Constant::getNullValue(Op0->getType());
927 if (match(Op1, m_Zero()))
931 if (match(Op1, m_One()))
934 // (X / Y) * Y -> X if the division is exact.
936 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
937 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
941 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
942 if (Value *V = SimplifyAndInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
945 // Try some generic simplifications for associative operations.
946 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, TLI, DT,
950 // Mul distributes over Add. Try some generic simplifications based on this.
951 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
952 TD, TLI, DT, MaxRecurse))
955 // If the operation is with the result of a select instruction, check whether
956 // operating on either branch of the select always yields the same value.
957 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
958 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, TLI, DT,
962 // If the operation is with the result of a phi instruction, check whether
963 // operating on all incoming values of the phi always yields the same value.
964 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
965 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, TLI, DT,
972 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
973 const TargetLibraryInfo *TLI,
974 const DominatorTree *DT) {
975 return ::SimplifyMulInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
978 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
979 /// fold the result. If not, this returns null.
980 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
981 const TargetData *TD, const TargetLibraryInfo *TLI,
982 const DominatorTree *DT, unsigned MaxRecurse) {
983 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
984 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
985 Constant *Ops[] = { C0, C1 };
986 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
990 bool isSigned = Opcode == Instruction::SDiv;
992 // X / undef -> undef
993 if (match(Op1, m_Undef()))
997 if (match(Op0, m_Undef()))
998 return Constant::getNullValue(Op0->getType());
1000 // 0 / X -> 0, we don't need to preserve faults!
1001 if (match(Op0, m_Zero()))
1005 if (match(Op1, m_One()))
1008 if (Op0->getType()->isIntegerTy(1))
1009 // It can't be division by zero, hence it must be division by one.
1014 return ConstantInt::get(Op0->getType(), 1);
1016 // (X * Y) / Y -> X if the multiplication does not overflow.
1017 Value *X = 0, *Y = 0;
1018 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
1019 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
1020 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
1021 // If the Mul knows it does not overflow, then we are good to go.
1022 if ((isSigned && Mul->hasNoSignedWrap()) ||
1023 (!isSigned && Mul->hasNoUnsignedWrap()))
1025 // If X has the form X = A / Y then X * Y cannot overflow.
1026 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
1027 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1031 // (X rem Y) / Y -> 0
1032 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1033 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1034 return Constant::getNullValue(Op0->getType());
1036 // If the operation is with the result of a select instruction, check whether
1037 // operating on either branch of the select always yields the same value.
1038 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1039 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT,
1043 // If the operation is with the result of a phi instruction, check whether
1044 // operating on all incoming values of the phi always yields the same value.
1045 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1046 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT,
1053 /// SimplifySDivInst - Given operands for an SDiv, see if we can
1054 /// fold the result. If not, this returns null.
1055 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1056 const TargetLibraryInfo *TLI,
1057 const DominatorTree *DT, unsigned MaxRecurse) {
1058 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, TLI, DT,
1065 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1066 const TargetLibraryInfo *TLI,
1067 const DominatorTree *DT) {
1068 return ::SimplifySDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1071 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
1072 /// fold the result. If not, this returns null.
1073 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1074 const TargetLibraryInfo *TLI,
1075 const DominatorTree *DT, unsigned MaxRecurse) {
1076 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, TLI, DT,
1083 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1084 const TargetLibraryInfo *TLI,
1085 const DominatorTree *DT) {
1086 return ::SimplifyUDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1089 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *,
1090 const TargetLibraryInfo *,
1091 const DominatorTree *, unsigned) {
1092 // undef / X -> undef (the undef could be a snan).
1093 if (match(Op0, m_Undef()))
1096 // X / undef -> undef
1097 if (match(Op1, m_Undef()))
1103 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1104 const TargetLibraryInfo *TLI,
1105 const DominatorTree *DT) {
1106 return ::SimplifyFDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1109 /// SimplifyRem - Given operands for an SRem or URem, see if we can
1110 /// fold the result. If not, this returns null.
1111 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1112 const TargetData *TD, const TargetLibraryInfo *TLI,
1113 const DominatorTree *DT, unsigned MaxRecurse) {
1114 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1115 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1116 Constant *Ops[] = { C0, C1 };
1117 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
1121 // X % undef -> undef
1122 if (match(Op1, m_Undef()))
1126 if (match(Op0, m_Undef()))
1127 return Constant::getNullValue(Op0->getType());
1129 // 0 % X -> 0, we don't need to preserve faults!
1130 if (match(Op0, m_Zero()))
1133 // X % 0 -> undef, we don't need to preserve faults!
1134 if (match(Op1, m_Zero()))
1135 return UndefValue::get(Op0->getType());
1138 if (match(Op1, m_One()))
1139 return Constant::getNullValue(Op0->getType());
1141 if (Op0->getType()->isIntegerTy(1))
1142 // It can't be remainder by zero, hence it must be remainder by one.
1143 return Constant::getNullValue(Op0->getType());
1147 return Constant::getNullValue(Op0->getType());
1149 // If the operation is with the result of a select instruction, check whether
1150 // operating on either branch of the select always yields the same value.
1151 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1152 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1155 // If the operation is with the result of a phi instruction, check whether
1156 // operating on all incoming values of the phi always yields the same value.
1157 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1158 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1164 /// SimplifySRemInst - Given operands for an SRem, see if we can
1165 /// fold the result. If not, this returns null.
1166 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1167 const TargetLibraryInfo *TLI,
1168 const DominatorTree *DT,
1169 unsigned MaxRecurse) {
1170 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, TD, TLI, DT, MaxRecurse))
1176 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1177 const TargetLibraryInfo *TLI,
1178 const DominatorTree *DT) {
1179 return ::SimplifySRemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1182 /// SimplifyURemInst - Given operands for a URem, see if we can
1183 /// fold the result. If not, this returns null.
1184 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1185 const TargetLibraryInfo *TLI,
1186 const DominatorTree *DT,
1187 unsigned MaxRecurse) {
1188 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, TD, TLI, DT, MaxRecurse))
1194 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1195 const TargetLibraryInfo *TLI,
1196 const DominatorTree *DT) {
1197 return ::SimplifyURemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1200 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *,
1201 const TargetLibraryInfo *,
1202 const DominatorTree *,
1204 // undef % X -> undef (the undef could be a snan).
1205 if (match(Op0, m_Undef()))
1208 // X % undef -> undef
1209 if (match(Op1, m_Undef()))
1215 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1216 const TargetLibraryInfo *TLI,
1217 const DominatorTree *DT) {
1218 return ::SimplifyFRemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1221 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1222 /// fold the result. If not, this returns null.
1223 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1224 const TargetData *TD, const TargetLibraryInfo *TLI,
1225 const DominatorTree *DT, unsigned MaxRecurse) {
1226 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1227 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1228 Constant *Ops[] = { C0, C1 };
1229 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
1233 // 0 shift by X -> 0
1234 if (match(Op0, m_Zero()))
1237 // X shift by 0 -> X
1238 if (match(Op1, m_Zero()))
1241 // X shift by undef -> undef because it may shift by the bitwidth.
1242 if (match(Op1, m_Undef()))
1245 // Shifting by the bitwidth or more is undefined.
1246 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
1247 if (CI->getValue().getLimitedValue() >=
1248 Op0->getType()->getScalarSizeInBits())
1249 return UndefValue::get(Op0->getType());
1251 // If the operation is with the result of a select instruction, check whether
1252 // operating on either branch of the select always yields the same value.
1253 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1254 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1257 // If the operation is with the result of a phi instruction, check whether
1258 // operating on all incoming values of the phi always yields the same value.
1259 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1260 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1266 /// SimplifyShlInst - Given operands for an Shl, see if we can
1267 /// fold the result. If not, this returns null.
1268 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1269 const TargetData *TD,
1270 const TargetLibraryInfo *TLI,
1271 const DominatorTree *DT, unsigned MaxRecurse) {
1272 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, TLI, DT, MaxRecurse))
1276 if (match(Op0, m_Undef()))
1277 return Constant::getNullValue(Op0->getType());
1279 // (X >> A) << A -> X
1281 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1286 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1287 const TargetData *TD, const TargetLibraryInfo *TLI,
1288 const DominatorTree *DT) {
1289 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
1292 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1293 /// fold the result. If not, this returns null.
1294 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1295 const TargetData *TD,
1296 const TargetLibraryInfo *TLI,
1297 const DominatorTree *DT,
1298 unsigned MaxRecurse) {
1299 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, TLI, DT, MaxRecurse))
1303 if (match(Op0, m_Undef()))
1304 return Constant::getNullValue(Op0->getType());
1306 // (X << A) >> A -> X
1308 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1309 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
1315 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1316 const TargetData *TD,
1317 const TargetLibraryInfo *TLI,
1318 const DominatorTree *DT) {
1319 return ::SimplifyLShrInst(Op0, Op1, isExact, TD, TLI, DT, RecursionLimit);
1322 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1323 /// fold the result. If not, this returns null.
1324 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1325 const TargetData *TD,
1326 const TargetLibraryInfo *TLI,
1327 const DominatorTree *DT,
1328 unsigned MaxRecurse) {
1329 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, TLI, DT, MaxRecurse))
1332 // all ones >>a X -> all ones
1333 if (match(Op0, m_AllOnes()))
1336 // undef >>a X -> all ones
1337 if (match(Op0, m_Undef()))
1338 return Constant::getAllOnesValue(Op0->getType());
1340 // (X << A) >> A -> X
1342 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1343 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
1349 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1350 const TargetData *TD,
1351 const TargetLibraryInfo *TLI,
1352 const DominatorTree *DT) {
1353 return ::SimplifyAShrInst(Op0, Op1, isExact, TD, TLI, DT, RecursionLimit);
1356 /// SimplifyAndInst - Given operands for an And, see if we can
1357 /// fold the result. If not, this returns null.
1358 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1359 const TargetLibraryInfo *TLI,
1360 const DominatorTree *DT,
1361 unsigned MaxRecurse) {
1362 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1363 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1364 Constant *Ops[] = { CLHS, CRHS };
1365 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1369 // Canonicalize the constant to the RHS.
1370 std::swap(Op0, Op1);
1374 if (match(Op1, m_Undef()))
1375 return Constant::getNullValue(Op0->getType());
1382 if (match(Op1, m_Zero()))
1386 if (match(Op1, m_AllOnes()))
1389 // A & ~A = ~A & A = 0
1390 if (match(Op0, m_Not(m_Specific(Op1))) ||
1391 match(Op1, m_Not(m_Specific(Op0))))
1392 return Constant::getNullValue(Op0->getType());
1395 Value *A = 0, *B = 0;
1396 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1397 (A == Op1 || B == Op1))
1401 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1402 (A == Op0 || B == Op0))
1405 // A & (-A) = A if A is a power of two or zero.
1406 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1407 match(Op1, m_Neg(m_Specific(Op0)))) {
1408 if (isPowerOfTwo(Op0, TD, /*OrZero*/true))
1410 if (isPowerOfTwo(Op1, TD, /*OrZero*/true))
1414 // Try some generic simplifications for associative operations.
1415 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, TLI,
1419 // And distributes over Or. Try some generic simplifications based on this.
1420 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1421 TD, TLI, DT, MaxRecurse))
1424 // And distributes over Xor. Try some generic simplifications based on this.
1425 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1426 TD, TLI, DT, MaxRecurse))
1429 // Or distributes over And. Try some generic simplifications based on this.
1430 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1431 TD, TLI, DT, MaxRecurse))
1434 // If the operation is with the result of a select instruction, check whether
1435 // operating on either branch of the select always yields the same value.
1436 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1437 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, TLI,
1441 // If the operation is with the result of a phi instruction, check whether
1442 // operating on all incoming values of the phi always yields the same value.
1443 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1444 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, TLI, DT,
1451 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1452 const TargetLibraryInfo *TLI,
1453 const DominatorTree *DT) {
1454 return ::SimplifyAndInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1457 /// SimplifyOrInst - Given operands for an Or, see if we can
1458 /// fold the result. If not, this returns null.
1459 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1460 const TargetLibraryInfo *TLI,
1461 const DominatorTree *DT, unsigned MaxRecurse) {
1462 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1463 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1464 Constant *Ops[] = { CLHS, CRHS };
1465 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1469 // Canonicalize the constant to the RHS.
1470 std::swap(Op0, Op1);
1474 if (match(Op1, m_Undef()))
1475 return Constant::getAllOnesValue(Op0->getType());
1482 if (match(Op1, m_Zero()))
1486 if (match(Op1, m_AllOnes()))
1489 // A | ~A = ~A | A = -1
1490 if (match(Op0, m_Not(m_Specific(Op1))) ||
1491 match(Op1, m_Not(m_Specific(Op0))))
1492 return Constant::getAllOnesValue(Op0->getType());
1495 Value *A = 0, *B = 0;
1496 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1497 (A == Op1 || B == Op1))
1501 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1502 (A == Op0 || B == Op0))
1505 // ~(A & ?) | A = -1
1506 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1507 (A == Op1 || B == Op1))
1508 return Constant::getAllOnesValue(Op1->getType());
1510 // A | ~(A & ?) = -1
1511 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1512 (A == Op0 || B == Op0))
1513 return Constant::getAllOnesValue(Op0->getType());
1515 // Try some generic simplifications for associative operations.
1516 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, TLI,
1520 // Or distributes over And. Try some generic simplifications based on this.
1521 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, TD,
1522 TLI, DT, MaxRecurse))
1525 // And distributes over Or. Try some generic simplifications based on this.
1526 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1527 TD, TLI, DT, MaxRecurse))
1530 // If the operation is with the result of a select instruction, check whether
1531 // operating on either branch of the select always yields the same value.
1532 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1533 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, TLI, DT,
1537 // If the operation is with the result of a phi instruction, check whether
1538 // operating on all incoming values of the phi always yields the same value.
1539 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1540 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, TLI, DT,
1547 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1548 const TargetLibraryInfo *TLI,
1549 const DominatorTree *DT) {
1550 return ::SimplifyOrInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1553 /// SimplifyXorInst - Given operands for a Xor, see if we can
1554 /// fold the result. If not, this returns null.
1555 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1556 const TargetLibraryInfo *TLI,
1557 const DominatorTree *DT, unsigned MaxRecurse) {
1558 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1559 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1560 Constant *Ops[] = { CLHS, CRHS };
1561 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1565 // Canonicalize the constant to the RHS.
1566 std::swap(Op0, Op1);
1569 // A ^ undef -> undef
1570 if (match(Op1, m_Undef()))
1574 if (match(Op1, m_Zero()))
1579 return Constant::getNullValue(Op0->getType());
1581 // A ^ ~A = ~A ^ A = -1
1582 if (match(Op0, m_Not(m_Specific(Op1))) ||
1583 match(Op1, m_Not(m_Specific(Op0))))
1584 return Constant::getAllOnesValue(Op0->getType());
1586 // Try some generic simplifications for associative operations.
1587 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, TLI,
1591 // And distributes over Xor. Try some generic simplifications based on this.
1592 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1593 TD, TLI, DT, MaxRecurse))
1596 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1597 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1598 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1599 // only if B and C are equal. If B and C are equal then (since we assume
1600 // that operands have already been simplified) "select(cond, B, C)" should
1601 // have been simplified to the common value of B and C already. Analysing
1602 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1603 // for threading over phi nodes.
1608 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1609 const TargetLibraryInfo *TLI,
1610 const DominatorTree *DT) {
1611 return ::SimplifyXorInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1614 static Type *GetCompareTy(Value *Op) {
1615 return CmpInst::makeCmpResultType(Op->getType());
1618 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1619 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1620 /// otherwise return null. Helper function for analyzing max/min idioms.
1621 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1622 Value *LHS, Value *RHS) {
1623 SelectInst *SI = dyn_cast<SelectInst>(V);
1626 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1629 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1630 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1632 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1633 LHS == CmpRHS && RHS == CmpLHS)
1639 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1640 /// fold the result. If not, this returns null.
1641 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1642 const TargetData *TD,
1643 const TargetLibraryInfo *TLI,
1644 const DominatorTree *DT,
1645 unsigned MaxRecurse) {
1646 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1647 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1649 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1650 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1651 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD, TLI);
1653 // If we have a constant, make sure it is on the RHS.
1654 std::swap(LHS, RHS);
1655 Pred = CmpInst::getSwappedPredicate(Pred);
1658 Type *ITy = GetCompareTy(LHS); // The return type.
1659 Type *OpTy = LHS->getType(); // The operand type.
1661 // icmp X, X -> true/false
1662 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1663 // because X could be 0.
1664 if (LHS == RHS || isa<UndefValue>(RHS))
1665 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1667 // Special case logic when the operands have i1 type.
1668 if (OpTy->getScalarType()->isIntegerTy(1)) {
1671 case ICmpInst::ICMP_EQ:
1673 if (match(RHS, m_One()))
1676 case ICmpInst::ICMP_NE:
1678 if (match(RHS, m_Zero()))
1681 case ICmpInst::ICMP_UGT:
1683 if (match(RHS, m_Zero()))
1686 case ICmpInst::ICMP_UGE:
1688 if (match(RHS, m_One()))
1691 case ICmpInst::ICMP_SLT:
1693 if (match(RHS, m_Zero()))
1696 case ICmpInst::ICMP_SLE:
1698 if (match(RHS, m_One()))
1704 // icmp <object*>, <object*/null> - Different identified objects have
1705 // different addresses (unless null), and what's more the address of an
1706 // identified local is never equal to another argument (again, barring null).
1707 // Note that generalizing to the case where LHS is a global variable address
1708 // or null is pointless, since if both LHS and RHS are constants then we
1709 // already constant folded the compare, and if only one of them is then we
1710 // moved it to RHS already.
1711 Value *LHSPtr = LHS->stripPointerCasts();
1712 Value *RHSPtr = RHS->stripPointerCasts();
1713 if (LHSPtr == RHSPtr)
1714 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1716 // Be more aggressive about stripping pointer adjustments when checking a
1717 // comparison of an alloca address to another object. We can rip off all
1718 // inbounds GEP operations, even if they are variable.
1719 LHSPtr = LHSPtr->stripInBoundsOffsets();
1720 if (llvm::isIdentifiedObject(LHSPtr)) {
1721 RHSPtr = RHSPtr->stripInBoundsOffsets();
1722 if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) {
1723 // If both sides are different identified objects, they aren't equal
1724 // unless they're null.
1725 if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) &&
1726 Pred == CmpInst::ICMP_EQ)
1727 return ConstantInt::get(ITy, false);
1729 // A local identified object (alloca or noalias call) can't equal any
1730 // incoming argument, unless they're both null.
1731 if (isa<Instruction>(LHSPtr) && isa<Argument>(RHSPtr) &&
1732 Pred == CmpInst::ICMP_EQ)
1733 return ConstantInt::get(ITy, false);
1736 // Assume that the constant null is on the right.
1737 if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) {
1738 if (Pred == CmpInst::ICMP_EQ)
1739 return ConstantInt::get(ITy, false);
1740 else if (Pred == CmpInst::ICMP_NE)
1741 return ConstantInt::get(ITy, true);
1743 } else if (isa<Argument>(LHSPtr)) {
1744 RHSPtr = RHSPtr->stripInBoundsOffsets();
1745 // An alloca can't be equal to an argument.
1746 if (isa<AllocaInst>(RHSPtr)) {
1747 if (Pred == CmpInst::ICMP_EQ)
1748 return ConstantInt::get(ITy, false);
1749 else if (Pred == CmpInst::ICMP_NE)
1750 return ConstantInt::get(ITy, true);
1754 // If we are comparing with zero then try hard since this is a common case.
1755 if (match(RHS, m_Zero())) {
1756 bool LHSKnownNonNegative, LHSKnownNegative;
1758 default: llvm_unreachable("Unknown ICmp predicate!");
1759 case ICmpInst::ICMP_ULT:
1760 return getFalse(ITy);
1761 case ICmpInst::ICMP_UGE:
1762 return getTrue(ITy);
1763 case ICmpInst::ICMP_EQ:
1764 case ICmpInst::ICMP_ULE:
1765 if (isKnownNonZero(LHS, TD))
1766 return getFalse(ITy);
1768 case ICmpInst::ICMP_NE:
1769 case ICmpInst::ICMP_UGT:
1770 if (isKnownNonZero(LHS, TD))
1771 return getTrue(ITy);
1773 case ICmpInst::ICMP_SLT:
1774 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1775 if (LHSKnownNegative)
1776 return getTrue(ITy);
1777 if (LHSKnownNonNegative)
1778 return getFalse(ITy);
1780 case ICmpInst::ICMP_SLE:
1781 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1782 if (LHSKnownNegative)
1783 return getTrue(ITy);
1784 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1785 return getFalse(ITy);
1787 case ICmpInst::ICMP_SGE:
1788 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1789 if (LHSKnownNegative)
1790 return getFalse(ITy);
1791 if (LHSKnownNonNegative)
1792 return getTrue(ITy);
1794 case ICmpInst::ICMP_SGT:
1795 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1796 if (LHSKnownNegative)
1797 return getFalse(ITy);
1798 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1799 return getTrue(ITy);
1804 // See if we are doing a comparison with a constant integer.
1805 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1806 // Rule out tautological comparisons (eg., ult 0 or uge 0).
1807 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
1808 if (RHS_CR.isEmptySet())
1809 return ConstantInt::getFalse(CI->getContext());
1810 if (RHS_CR.isFullSet())
1811 return ConstantInt::getTrue(CI->getContext());
1813 // Many binary operators with constant RHS have easy to compute constant
1814 // range. Use them to check whether the comparison is a tautology.
1815 uint32_t Width = CI->getBitWidth();
1816 APInt Lower = APInt(Width, 0);
1817 APInt Upper = APInt(Width, 0);
1819 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
1820 // 'urem x, CI2' produces [0, CI2).
1821 Upper = CI2->getValue();
1822 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
1823 // 'srem x, CI2' produces (-|CI2|, |CI2|).
1824 Upper = CI2->getValue().abs();
1825 Lower = (-Upper) + 1;
1826 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
1827 // 'udiv CI2, x' produces [0, CI2].
1828 Upper = CI2->getValue() + 1;
1829 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
1830 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
1831 APInt NegOne = APInt::getAllOnesValue(Width);
1833 Upper = NegOne.udiv(CI2->getValue()) + 1;
1834 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
1835 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
1836 APInt IntMin = APInt::getSignedMinValue(Width);
1837 APInt IntMax = APInt::getSignedMaxValue(Width);
1838 APInt Val = CI2->getValue().abs();
1839 if (!Val.isMinValue()) {
1840 Lower = IntMin.sdiv(Val);
1841 Upper = IntMax.sdiv(Val) + 1;
1843 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
1844 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
1845 APInt NegOne = APInt::getAllOnesValue(Width);
1846 if (CI2->getValue().ult(Width))
1847 Upper = NegOne.lshr(CI2->getValue()) + 1;
1848 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
1849 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
1850 APInt IntMin = APInt::getSignedMinValue(Width);
1851 APInt IntMax = APInt::getSignedMaxValue(Width);
1852 if (CI2->getValue().ult(Width)) {
1853 Lower = IntMin.ashr(CI2->getValue());
1854 Upper = IntMax.ashr(CI2->getValue()) + 1;
1856 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
1857 // 'or x, CI2' produces [CI2, UINT_MAX].
1858 Lower = CI2->getValue();
1859 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
1860 // 'and x, CI2' produces [0, CI2].
1861 Upper = CI2->getValue() + 1;
1863 if (Lower != Upper) {
1864 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
1865 if (RHS_CR.contains(LHS_CR))
1866 return ConstantInt::getTrue(RHS->getContext());
1867 if (RHS_CR.inverse().contains(LHS_CR))
1868 return ConstantInt::getFalse(RHS->getContext());
1872 // Compare of cast, for example (zext X) != 0 -> X != 0
1873 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1874 Instruction *LI = cast<CastInst>(LHS);
1875 Value *SrcOp = LI->getOperand(0);
1876 Type *SrcTy = SrcOp->getType();
1877 Type *DstTy = LI->getType();
1879 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1880 // if the integer type is the same size as the pointer type.
1881 if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
1882 TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1883 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1884 // Transfer the cast to the constant.
1885 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1886 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1887 TD, TLI, DT, MaxRecurse-1))
1889 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1890 if (RI->getOperand(0)->getType() == SrcTy)
1891 // Compare without the cast.
1892 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1893 TD, TLI, DT, MaxRecurse-1))
1898 if (isa<ZExtInst>(LHS)) {
1899 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1901 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1902 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1903 // Compare X and Y. Note that signed predicates become unsigned.
1904 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1905 SrcOp, RI->getOperand(0), TD, TLI, DT,
1909 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1910 // too. If not, then try to deduce the result of the comparison.
1911 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1912 // Compute the constant that would happen if we truncated to SrcTy then
1913 // reextended to DstTy.
1914 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1915 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1917 // If the re-extended constant didn't change then this is effectively
1918 // also a case of comparing two zero-extended values.
1919 if (RExt == CI && MaxRecurse)
1920 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1921 SrcOp, Trunc, TD, TLI, DT, MaxRecurse-1))
1924 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1925 // there. Use this to work out the result of the comparison.
1928 default: llvm_unreachable("Unknown ICmp predicate!");
1930 case ICmpInst::ICMP_EQ:
1931 case ICmpInst::ICMP_UGT:
1932 case ICmpInst::ICMP_UGE:
1933 return ConstantInt::getFalse(CI->getContext());
1935 case ICmpInst::ICMP_NE:
1936 case ICmpInst::ICMP_ULT:
1937 case ICmpInst::ICMP_ULE:
1938 return ConstantInt::getTrue(CI->getContext());
1940 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1941 // is non-negative then LHS <s RHS.
1942 case ICmpInst::ICMP_SGT:
1943 case ICmpInst::ICMP_SGE:
1944 return CI->getValue().isNegative() ?
1945 ConstantInt::getTrue(CI->getContext()) :
1946 ConstantInt::getFalse(CI->getContext());
1948 case ICmpInst::ICMP_SLT:
1949 case ICmpInst::ICMP_SLE:
1950 return CI->getValue().isNegative() ?
1951 ConstantInt::getFalse(CI->getContext()) :
1952 ConstantInt::getTrue(CI->getContext());
1958 if (isa<SExtInst>(LHS)) {
1959 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1961 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1962 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1963 // Compare X and Y. Note that the predicate does not change.
1964 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1965 TD, TLI, DT, MaxRecurse-1))
1968 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1969 // too. If not, then try to deduce the result of the comparison.
1970 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1971 // Compute the constant that would happen if we truncated to SrcTy then
1972 // reextended to DstTy.
1973 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1974 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1976 // If the re-extended constant didn't change then this is effectively
1977 // also a case of comparing two sign-extended values.
1978 if (RExt == CI && MaxRecurse)
1979 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, TLI, DT,
1983 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1984 // bits there. Use this to work out the result of the comparison.
1987 default: llvm_unreachable("Unknown ICmp predicate!");
1988 case ICmpInst::ICMP_EQ:
1989 return ConstantInt::getFalse(CI->getContext());
1990 case ICmpInst::ICMP_NE:
1991 return ConstantInt::getTrue(CI->getContext());
1993 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1995 case ICmpInst::ICMP_SGT:
1996 case ICmpInst::ICMP_SGE:
1997 return CI->getValue().isNegative() ?
1998 ConstantInt::getTrue(CI->getContext()) :
1999 ConstantInt::getFalse(CI->getContext());
2000 case ICmpInst::ICMP_SLT:
2001 case ICmpInst::ICMP_SLE:
2002 return CI->getValue().isNegative() ?
2003 ConstantInt::getFalse(CI->getContext()) :
2004 ConstantInt::getTrue(CI->getContext());
2006 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
2008 case ICmpInst::ICMP_UGT:
2009 case ICmpInst::ICMP_UGE:
2010 // Comparison is true iff the LHS <s 0.
2012 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
2013 Constant::getNullValue(SrcTy),
2014 TD, TLI, DT, MaxRecurse-1))
2017 case ICmpInst::ICMP_ULT:
2018 case ICmpInst::ICMP_ULE:
2019 // Comparison is true iff the LHS >=s 0.
2021 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
2022 Constant::getNullValue(SrcTy),
2023 TD, TLI, DT, MaxRecurse-1))
2032 // Special logic for binary operators.
2033 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2034 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2035 if (MaxRecurse && (LBO || RBO)) {
2036 // Analyze the case when either LHS or RHS is an add instruction.
2037 Value *A = 0, *B = 0, *C = 0, *D = 0;
2038 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2039 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2040 if (LBO && LBO->getOpcode() == Instruction::Add) {
2041 A = LBO->getOperand(0); B = LBO->getOperand(1);
2042 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
2043 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
2044 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
2046 if (RBO && RBO->getOpcode() == Instruction::Add) {
2047 C = RBO->getOperand(0); D = RBO->getOperand(1);
2048 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
2049 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2050 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2053 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2054 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2055 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2056 Constant::getNullValue(RHS->getType()),
2057 TD, TLI, DT, MaxRecurse-1))
2060 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2061 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2062 if (Value *V = SimplifyICmpInst(Pred,
2063 Constant::getNullValue(LHS->getType()),
2064 C == LHS ? D : C, TD, TLI, DT, MaxRecurse-1))
2067 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2068 if (A && C && (A == C || A == D || B == C || B == D) &&
2069 NoLHSWrapProblem && NoRHSWrapProblem) {
2070 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2071 Value *Y = (A == C || A == D) ? B : A;
2072 Value *Z = (C == A || C == B) ? D : C;
2073 if (Value *V = SimplifyICmpInst(Pred, Y, Z, TD, TLI, DT, MaxRecurse-1))
2078 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2079 bool KnownNonNegative, KnownNegative;
2083 case ICmpInst::ICMP_SGT:
2084 case ICmpInst::ICMP_SGE:
2085 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD);
2086 if (!KnownNonNegative)
2089 case ICmpInst::ICMP_EQ:
2090 case ICmpInst::ICMP_UGT:
2091 case ICmpInst::ICMP_UGE:
2092 return getFalse(ITy);
2093 case ICmpInst::ICMP_SLT:
2094 case ICmpInst::ICMP_SLE:
2095 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD);
2096 if (!KnownNonNegative)
2099 case ICmpInst::ICMP_NE:
2100 case ICmpInst::ICMP_ULT:
2101 case ICmpInst::ICMP_ULE:
2102 return getTrue(ITy);
2105 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2106 bool KnownNonNegative, KnownNegative;
2110 case ICmpInst::ICMP_SGT:
2111 case ICmpInst::ICMP_SGE:
2112 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD);
2113 if (!KnownNonNegative)
2116 case ICmpInst::ICMP_NE:
2117 case ICmpInst::ICMP_UGT:
2118 case ICmpInst::ICMP_UGE:
2119 return getTrue(ITy);
2120 case ICmpInst::ICMP_SLT:
2121 case ICmpInst::ICMP_SLE:
2122 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD);
2123 if (!KnownNonNegative)
2126 case ICmpInst::ICMP_EQ:
2127 case ICmpInst::ICMP_ULT:
2128 case ICmpInst::ICMP_ULE:
2129 return getFalse(ITy);
2134 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2135 // icmp pred (X /u Y), X
2136 if (Pred == ICmpInst::ICMP_UGT)
2137 return getFalse(ITy);
2138 if (Pred == ICmpInst::ICMP_ULE)
2139 return getTrue(ITy);
2142 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2143 LBO->getOperand(1) == RBO->getOperand(1)) {
2144 switch (LBO->getOpcode()) {
2146 case Instruction::UDiv:
2147 case Instruction::LShr:
2148 if (ICmpInst::isSigned(Pred))
2151 case Instruction::SDiv:
2152 case Instruction::AShr:
2153 if (!LBO->isExact() || !RBO->isExact())
2155 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2156 RBO->getOperand(0), TD, TLI, DT, MaxRecurse-1))
2159 case Instruction::Shl: {
2160 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2161 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2164 if (!NSW && ICmpInst::isSigned(Pred))
2166 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2167 RBO->getOperand(0), TD, TLI, DT, MaxRecurse-1))
2174 // Simplify comparisons involving max/min.
2176 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2177 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2179 // Signed variants on "max(a,b)>=a -> true".
2180 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2181 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2182 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2183 // We analyze this as smax(A, B) pred A.
2185 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2186 (A == LHS || B == LHS)) {
2187 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2188 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2189 // We analyze this as smax(A, B) swapped-pred A.
2190 P = CmpInst::getSwappedPredicate(Pred);
2191 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2192 (A == RHS || B == RHS)) {
2193 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2194 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2195 // We analyze this as smax(-A, -B) swapped-pred -A.
2196 // Note that we do not need to actually form -A or -B thanks to EqP.
2197 P = CmpInst::getSwappedPredicate(Pred);
2198 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2199 (A == LHS || B == LHS)) {
2200 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2201 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2202 // We analyze this as smax(-A, -B) pred -A.
2203 // Note that we do not need to actually form -A or -B thanks to EqP.
2206 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2207 // Cases correspond to "max(A, B) p A".
2211 case CmpInst::ICMP_EQ:
2212 case CmpInst::ICMP_SLE:
2213 // Equivalent to "A EqP B". This may be the same as the condition tested
2214 // in the max/min; if so, we can just return that.
2215 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2217 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2219 // Otherwise, see if "A EqP B" simplifies.
2221 if (Value *V = SimplifyICmpInst(EqP, A, B, TD, TLI, DT, MaxRecurse-1))
2224 case CmpInst::ICMP_NE:
2225 case CmpInst::ICMP_SGT: {
2226 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2227 // Equivalent to "A InvEqP B". This may be the same as the condition
2228 // tested in the max/min; if so, we can just return that.
2229 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2231 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2233 // Otherwise, see if "A InvEqP B" simplifies.
2235 if (Value *V = SimplifyICmpInst(InvEqP, A, B, TD, TLI, DT, MaxRecurse-1))
2239 case CmpInst::ICMP_SGE:
2241 return getTrue(ITy);
2242 case CmpInst::ICMP_SLT:
2244 return getFalse(ITy);
2248 // Unsigned variants on "max(a,b)>=a -> true".
2249 P = CmpInst::BAD_ICMP_PREDICATE;
2250 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2251 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2252 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2253 // We analyze this as umax(A, B) pred A.
2255 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2256 (A == LHS || B == LHS)) {
2257 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2258 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2259 // We analyze this as umax(A, B) swapped-pred A.
2260 P = CmpInst::getSwappedPredicate(Pred);
2261 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2262 (A == RHS || B == RHS)) {
2263 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2264 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2265 // We analyze this as umax(-A, -B) swapped-pred -A.
2266 // Note that we do not need to actually form -A or -B thanks to EqP.
2267 P = CmpInst::getSwappedPredicate(Pred);
2268 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2269 (A == LHS || B == LHS)) {
2270 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2271 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2272 // We analyze this as umax(-A, -B) pred -A.
2273 // Note that we do not need to actually form -A or -B thanks to EqP.
2276 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2277 // Cases correspond to "max(A, B) p A".
2281 case CmpInst::ICMP_EQ:
2282 case CmpInst::ICMP_ULE:
2283 // Equivalent to "A EqP B". This may be the same as the condition tested
2284 // in the max/min; if so, we can just return that.
2285 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2287 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2289 // Otherwise, see if "A EqP B" simplifies.
2291 if (Value *V = SimplifyICmpInst(EqP, A, B, TD, TLI, DT, MaxRecurse-1))
2294 case CmpInst::ICMP_NE:
2295 case CmpInst::ICMP_UGT: {
2296 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2297 // Equivalent to "A InvEqP B". This may be the same as the condition
2298 // tested in the max/min; if so, we can just return that.
2299 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2301 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2303 // Otherwise, see if "A InvEqP B" simplifies.
2305 if (Value *V = SimplifyICmpInst(InvEqP, A, B, TD, TLI, DT, MaxRecurse-1))
2309 case CmpInst::ICMP_UGE:
2311 return getTrue(ITy);
2312 case CmpInst::ICMP_ULT:
2314 return getFalse(ITy);
2318 // Variants on "max(x,y) >= min(x,z)".
2320 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2321 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2322 (A == C || A == D || B == C || B == D)) {
2323 // max(x, ?) pred min(x, ?).
2324 if (Pred == CmpInst::ICMP_SGE)
2326 return getTrue(ITy);
2327 if (Pred == CmpInst::ICMP_SLT)
2329 return getFalse(ITy);
2330 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2331 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2332 (A == C || A == D || B == C || B == D)) {
2333 // min(x, ?) pred max(x, ?).
2334 if (Pred == CmpInst::ICMP_SLE)
2336 return getTrue(ITy);
2337 if (Pred == CmpInst::ICMP_SGT)
2339 return getFalse(ITy);
2340 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2341 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2342 (A == C || A == D || B == C || B == D)) {
2343 // max(x, ?) pred min(x, ?).
2344 if (Pred == CmpInst::ICMP_UGE)
2346 return getTrue(ITy);
2347 if (Pred == CmpInst::ICMP_ULT)
2349 return getFalse(ITy);
2350 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2351 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2352 (A == C || A == D || B == C || B == D)) {
2353 // min(x, ?) pred max(x, ?).
2354 if (Pred == CmpInst::ICMP_ULE)
2356 return getTrue(ITy);
2357 if (Pred == CmpInst::ICMP_UGT)
2359 return getFalse(ITy);
2362 // Simplify comparisons of GEPs.
2363 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
2364 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
2365 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
2366 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
2367 (ICmpInst::isEquality(Pred) ||
2368 (GLHS->isInBounds() && GRHS->isInBounds() &&
2369 Pred == ICmpInst::getSignedPredicate(Pred)))) {
2370 // The bases are equal and the indices are constant. Build a constant
2371 // expression GEP with the same indices and a null base pointer to see
2372 // what constant folding can make out of it.
2373 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
2374 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
2375 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS);
2377 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
2378 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS);
2379 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
2384 // If the comparison is with the result of a select instruction, check whether
2385 // comparing with either branch of the select always yields the same value.
2386 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2387 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2390 // If the comparison is with the result of a phi instruction, check whether
2391 // doing the compare with each incoming phi value yields a common result.
2392 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2393 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2399 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2400 const TargetData *TD,
2401 const TargetLibraryInfo *TLI,
2402 const DominatorTree *DT) {
2403 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2406 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
2407 /// fold the result. If not, this returns null.
2408 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2409 const TargetData *TD,
2410 const TargetLibraryInfo *TLI,
2411 const DominatorTree *DT,
2412 unsigned MaxRecurse) {
2413 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2414 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
2416 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2417 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2418 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD, TLI);
2420 // If we have a constant, make sure it is on the RHS.
2421 std::swap(LHS, RHS);
2422 Pred = CmpInst::getSwappedPredicate(Pred);
2425 // Fold trivial predicates.
2426 if (Pred == FCmpInst::FCMP_FALSE)
2427 return ConstantInt::get(GetCompareTy(LHS), 0);
2428 if (Pred == FCmpInst::FCMP_TRUE)
2429 return ConstantInt::get(GetCompareTy(LHS), 1);
2431 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
2432 return UndefValue::get(GetCompareTy(LHS));
2434 // fcmp x,x -> true/false. Not all compares are foldable.
2436 if (CmpInst::isTrueWhenEqual(Pred))
2437 return ConstantInt::get(GetCompareTy(LHS), 1);
2438 if (CmpInst::isFalseWhenEqual(Pred))
2439 return ConstantInt::get(GetCompareTy(LHS), 0);
2442 // Handle fcmp with constant RHS
2443 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2444 // If the constant is a nan, see if we can fold the comparison based on it.
2445 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2446 if (CFP->getValueAPF().isNaN()) {
2447 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
2448 return ConstantInt::getFalse(CFP->getContext());
2449 assert(FCmpInst::isUnordered(Pred) &&
2450 "Comparison must be either ordered or unordered!");
2451 // True if unordered.
2452 return ConstantInt::getTrue(CFP->getContext());
2454 // Check whether the constant is an infinity.
2455 if (CFP->getValueAPF().isInfinity()) {
2456 if (CFP->getValueAPF().isNegative()) {
2458 case FCmpInst::FCMP_OLT:
2459 // No value is ordered and less than negative infinity.
2460 return ConstantInt::getFalse(CFP->getContext());
2461 case FCmpInst::FCMP_UGE:
2462 // All values are unordered with or at least negative infinity.
2463 return ConstantInt::getTrue(CFP->getContext());
2469 case FCmpInst::FCMP_OGT:
2470 // No value is ordered and greater than infinity.
2471 return ConstantInt::getFalse(CFP->getContext());
2472 case FCmpInst::FCMP_ULE:
2473 // All values are unordered with and at most infinity.
2474 return ConstantInt::getTrue(CFP->getContext());
2483 // If the comparison is with the result of a select instruction, check whether
2484 // comparing with either branch of the select always yields the same value.
2485 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2486 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2489 // If the comparison is with the result of a phi instruction, check whether
2490 // doing the compare with each incoming phi value yields a common result.
2491 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2492 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2498 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2499 const TargetData *TD,
2500 const TargetLibraryInfo *TLI,
2501 const DominatorTree *DT) {
2502 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2505 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
2506 /// the result. If not, this returns null.
2507 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
2508 const TargetData *TD, const DominatorTree *) {
2509 // select true, X, Y -> X
2510 // select false, X, Y -> Y
2511 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
2512 return CB->getZExtValue() ? TrueVal : FalseVal;
2514 // select C, X, X -> X
2515 if (TrueVal == FalseVal)
2518 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
2519 if (isa<Constant>(TrueVal))
2523 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
2525 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
2531 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
2532 /// fold the result. If not, this returns null.
2533 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const TargetData *TD,
2534 const DominatorTree *) {
2535 // The type of the GEP pointer operand.
2536 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType());
2537 // The GEP pointer operand is not a pointer, it's a vector of pointers.
2541 // getelementptr P -> P.
2542 if (Ops.size() == 1)
2545 if (isa<UndefValue>(Ops[0])) {
2546 // Compute the (pointer) type returned by the GEP instruction.
2547 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
2548 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
2549 return UndefValue::get(GEPTy);
2552 if (Ops.size() == 2) {
2553 // getelementptr P, 0 -> P.
2554 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
2557 // getelementptr P, N -> P if P points to a type of zero size.
2559 Type *Ty = PtrTy->getElementType();
2560 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
2565 // Check to see if this is constant foldable.
2566 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2567 if (!isa<Constant>(Ops[i]))
2570 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
2573 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
2574 /// can fold the result. If not, this returns null.
2575 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
2576 ArrayRef<unsigned> Idxs,
2578 const DominatorTree *) {
2579 if (Constant *CAgg = dyn_cast<Constant>(Agg))
2580 if (Constant *CVal = dyn_cast<Constant>(Val))
2581 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
2583 // insertvalue x, undef, n -> x
2584 if (match(Val, m_Undef()))
2587 // insertvalue x, (extractvalue y, n), n
2588 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
2589 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
2590 EV->getIndices() == Idxs) {
2591 // insertvalue undef, (extractvalue y, n), n -> y
2592 if (match(Agg, m_Undef()))
2593 return EV->getAggregateOperand();
2595 // insertvalue y, (extractvalue y, n), n -> y
2596 if (Agg == EV->getAggregateOperand())
2603 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
2604 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
2605 // If all of the PHI's incoming values are the same then replace the PHI node
2606 // with the common value.
2607 Value *CommonValue = 0;
2608 bool HasUndefInput = false;
2609 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
2610 Value *Incoming = PN->getIncomingValue(i);
2611 // If the incoming value is the phi node itself, it can safely be skipped.
2612 if (Incoming == PN) continue;
2613 if (isa<UndefValue>(Incoming)) {
2614 // Remember that we saw an undef value, but otherwise ignore them.
2615 HasUndefInput = true;
2618 if (CommonValue && Incoming != CommonValue)
2619 return 0; // Not the same, bail out.
2620 CommonValue = Incoming;
2623 // If CommonValue is null then all of the incoming values were either undef or
2624 // equal to the phi node itself.
2626 return UndefValue::get(PN->getType());
2628 // If we have a PHI node like phi(X, undef, X), where X is defined by some
2629 // instruction, we cannot return X as the result of the PHI node unless it
2630 // dominates the PHI block.
2632 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
2637 //=== Helper functions for higher up the class hierarchy.
2639 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
2640 /// fold the result. If not, this returns null.
2641 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2642 const TargetData *TD,
2643 const TargetLibraryInfo *TLI,
2644 const DominatorTree *DT,
2645 unsigned MaxRecurse) {
2647 case Instruction::Add:
2648 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2649 TD, TLI, DT, MaxRecurse);
2650 case Instruction::Sub:
2651 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2652 TD, TLI, DT, MaxRecurse);
2653 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, TD, TLI, DT,
2655 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, TLI, DT,
2657 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, TLI, DT,
2659 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, TLI, DT,
2661 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, TD, TLI, DT,
2663 case Instruction::URem: return SimplifyURemInst(LHS, RHS, TD, TLI, DT,
2665 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, TD, TLI, DT,
2667 case Instruction::Shl:
2668 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2669 TD, TLI, DT, MaxRecurse);
2670 case Instruction::LShr:
2671 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, TD, TLI, DT,
2673 case Instruction::AShr:
2674 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, TD, TLI, DT,
2676 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, TLI, DT,
2678 case Instruction::Or: return SimplifyOrInst (LHS, RHS, TD, TLI, DT,
2680 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, TLI, DT,
2683 if (Constant *CLHS = dyn_cast<Constant>(LHS))
2684 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
2685 Constant *COps[] = {CLHS, CRHS};
2686 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, TD, TLI);
2689 // If the operation is associative, try some generic simplifications.
2690 if (Instruction::isAssociative(Opcode))
2691 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, TLI, DT,
2695 // If the operation is with the result of a select instruction, check whether
2696 // operating on either branch of the select always yields the same value.
2697 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2698 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, TLI, DT,
2702 // If the operation is with the result of a phi instruction, check whether
2703 // operating on all incoming values of the phi always yields the same value.
2704 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2705 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, TLI, DT,
2713 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2714 const TargetData *TD, const TargetLibraryInfo *TLI,
2715 const DominatorTree *DT) {
2716 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, TLI, DT, RecursionLimit);
2719 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
2720 /// fold the result.
2721 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2722 const TargetData *TD,
2723 const TargetLibraryInfo *TLI,
2724 const DominatorTree *DT,
2725 unsigned MaxRecurse) {
2726 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
2727 return SimplifyICmpInst(Predicate, LHS, RHS, TD, TLI, DT, MaxRecurse);
2728 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, TLI, DT, MaxRecurse);
2731 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2732 const TargetData *TD, const TargetLibraryInfo *TLI,
2733 const DominatorTree *DT) {
2734 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2737 static Value *SimplifyCallInst(CallInst *CI) {
2738 // call undef -> undef
2739 if (isa<UndefValue>(CI->getCalledValue()))
2740 return UndefValue::get(CI->getType());
2745 /// SimplifyInstruction - See if we can compute a simplified version of this
2746 /// instruction. If not, this returns null.
2747 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
2748 const TargetLibraryInfo *TLI,
2749 const DominatorTree *DT) {
2752 switch (I->getOpcode()) {
2754 Result = ConstantFoldInstruction(I, TD, TLI);
2756 case Instruction::Add:
2757 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
2758 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2759 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2762 case Instruction::Sub:
2763 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
2764 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2765 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2768 case Instruction::Mul:
2769 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2771 case Instruction::SDiv:
2772 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2774 case Instruction::UDiv:
2775 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2777 case Instruction::FDiv:
2778 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2780 case Instruction::SRem:
2781 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2783 case Instruction::URem:
2784 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2786 case Instruction::FRem:
2787 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2789 case Instruction::Shl:
2790 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
2791 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2792 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2795 case Instruction::LShr:
2796 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
2797 cast<BinaryOperator>(I)->isExact(),
2800 case Instruction::AShr:
2801 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
2802 cast<BinaryOperator>(I)->isExact(),
2805 case Instruction::And:
2806 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2808 case Instruction::Or:
2809 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2811 case Instruction::Xor:
2812 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2814 case Instruction::ICmp:
2815 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
2816 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2818 case Instruction::FCmp:
2819 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
2820 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2822 case Instruction::Select:
2823 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
2824 I->getOperand(2), TD, DT);
2826 case Instruction::GetElementPtr: {
2827 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
2828 Result = SimplifyGEPInst(Ops, TD, DT);
2831 case Instruction::InsertValue: {
2832 InsertValueInst *IV = cast<InsertValueInst>(I);
2833 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
2834 IV->getInsertedValueOperand(),
2835 IV->getIndices(), TD, DT);
2838 case Instruction::PHI:
2839 Result = SimplifyPHINode(cast<PHINode>(I), DT);
2841 case Instruction::Call:
2842 Result = SimplifyCallInst(cast<CallInst>(I));
2846 /// If called on unreachable code, the above logic may report that the
2847 /// instruction simplified to itself. Make life easier for users by
2848 /// detecting that case here, returning a safe value instead.
2849 return Result == I ? UndefValue::get(I->getType()) : Result;
2852 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
2853 /// delete the From instruction. In addition to a basic RAUW, this does a
2854 /// recursive simplification of the newly formed instructions. This catches
2855 /// things where one simplification exposes other opportunities. This only
2856 /// simplifies and deletes scalar operations, it does not change the CFG.
2858 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
2859 const TargetData *TD,
2860 const TargetLibraryInfo *TLI,
2861 const DominatorTree *DT) {
2862 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
2864 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
2865 // we can know if it gets deleted out from under us or replaced in a
2866 // recursive simplification.
2867 WeakVH FromHandle(From);
2868 WeakVH ToHandle(To);
2870 while (!From->use_empty()) {
2871 // Update the instruction to use the new value.
2872 Use &TheUse = From->use_begin().getUse();
2873 Instruction *User = cast<Instruction>(TheUse.getUser());
2876 // Check to see if the instruction can be folded due to the operand
2877 // replacement. For example changing (or X, Y) into (or X, -1) can replace
2878 // the 'or' with -1.
2879 Value *SimplifiedVal;
2881 // Sanity check to make sure 'User' doesn't dangle across
2882 // SimplifyInstruction.
2883 AssertingVH<> UserHandle(User);
2885 SimplifiedVal = SimplifyInstruction(User, TD, TLI, DT);
2886 if (SimplifiedVal == 0) continue;
2889 // Recursively simplify this user to the new value.
2890 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, TLI, DT);
2891 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
2894 assert(ToHandle && "To value deleted by recursive simplification?");
2896 // If the recursive simplification ended up revisiting and deleting
2897 // 'From' then we're done.
2902 // If 'From' has value handles referring to it, do a real RAUW to update them.
2903 From->replaceAllUsesWith(To);
2905 From->eraseFromParent();