1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements routines for folding instructions into simpler forms
11 // that do not require creating new instructions. This does constant folding
12 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
13 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
14 // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
15 // simplified: This is usually true and assuming it simplifies the logic (if
16 // they have not been simplified then results are correct but maybe suboptimal).
18 //===----------------------------------------------------------------------===//
20 #define DEBUG_TYPE "instsimplify"
21 #include "llvm/Operator.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/Analysis/InstructionSimplify.h"
24 #include "llvm/Analysis/ConstantFolding.h"
25 #include "llvm/Analysis/Dominators.h"
26 #include "llvm/Analysis/ValueTracking.h"
27 #include "llvm/Support/ConstantRange.h"
28 #include "llvm/Support/PatternMatch.h"
29 #include "llvm/Support/ValueHandle.h"
30 #include "llvm/Target/TargetData.h"
32 using namespace llvm::PatternMatch;
34 enum { RecursionLimit = 3 };
36 STATISTIC(NumExpand, "Number of expansions");
37 STATISTIC(NumFactor , "Number of factorizations");
38 STATISTIC(NumReassoc, "Number of reassociations");
40 static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
41 const TargetLibraryInfo *, const DominatorTree *,
43 static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
44 const TargetLibraryInfo *, const DominatorTree *,
46 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
47 const TargetLibraryInfo *, const DominatorTree *,
49 static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
50 const TargetLibraryInfo *, const DominatorTree *,
52 static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
53 const TargetLibraryInfo *, const DominatorTree *,
56 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
57 /// a vector with every element false, as appropriate for the type.
58 static Constant *getFalse(Type *Ty) {
59 assert(Ty->getScalarType()->isIntegerTy(1) &&
60 "Expected i1 type or a vector of i1!");
61 return Constant::getNullValue(Ty);
64 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
65 /// a vector with every element true, as appropriate for the type.
66 static Constant *getTrue(Type *Ty) {
67 assert(Ty->getScalarType()->isIntegerTy(1) &&
68 "Expected i1 type or a vector of i1!");
69 return Constant::getAllOnesValue(Ty);
72 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
73 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
75 CmpInst *Cmp = dyn_cast<CmpInst>(V);
78 CmpInst::Predicate CPred = Cmp->getPredicate();
79 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
80 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
82 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
86 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
87 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
88 Instruction *I = dyn_cast<Instruction>(V);
90 // Arguments and constants dominate all instructions.
93 // If we have a DominatorTree then do a precise test.
95 return DT->dominates(I, P);
97 // Otherwise, if the instruction is in the entry block, and is not an invoke,
98 // then it obviously dominates all phi nodes.
99 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
106 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
107 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
108 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
109 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
110 /// Returns the simplified value, or null if no simplification was performed.
111 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
112 unsigned OpcToExpand, const TargetData *TD,
113 const TargetLibraryInfo *TLI, const DominatorTree *DT,
114 unsigned MaxRecurse) {
115 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
116 // Recursion is always used, so bail out at once if we already hit the limit.
120 // Check whether the expression has the form "(A op' B) op C".
121 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
122 if (Op0->getOpcode() == OpcodeToExpand) {
123 // It does! Try turning it into "(A op C) op' (B op C)".
124 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
125 // Do "A op C" and "B op C" both simplify?
126 if (Value *L = SimplifyBinOp(Opcode, A, C, TD, TLI, DT, MaxRecurse))
127 if (Value *R = SimplifyBinOp(Opcode, B, C, TD, TLI, DT, MaxRecurse)) {
128 // They do! Return "L op' R" if it simplifies or is already available.
129 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
130 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
131 && L == B && R == A)) {
135 // Otherwise return "L op' R" if it simplifies.
136 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, TLI, DT,
144 // Check whether the expression has the form "A op (B op' C)".
145 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
146 if (Op1->getOpcode() == OpcodeToExpand) {
147 // It does! Try turning it into "(A op B) op' (A op C)".
148 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
149 // Do "A op B" and "A op C" both simplify?
150 if (Value *L = SimplifyBinOp(Opcode, A, B, TD, TLI, DT, MaxRecurse))
151 if (Value *R = SimplifyBinOp(Opcode, A, C, TD, TLI, DT, MaxRecurse)) {
152 // They do! Return "L op' R" if it simplifies or is already available.
153 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
154 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
155 && L == C && R == B)) {
159 // Otherwise return "L op' R" if it simplifies.
160 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, TLI, DT,
171 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
172 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
173 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
174 /// Returns the simplified value, or null if no simplification was performed.
175 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
176 unsigned OpcToExtract, const TargetData *TD,
177 const TargetLibraryInfo *TLI,
178 const DominatorTree *DT,
179 unsigned MaxRecurse) {
180 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
181 // Recursion is always used, so bail out at once if we already hit the limit.
185 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
186 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
188 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
189 !Op1 || Op1->getOpcode() != OpcodeToExtract)
192 // The expression has the form "(A op' B) op (C op' D)".
193 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
194 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
196 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
197 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
198 // commutative case, "(A op' B) op (C op' A)"?
199 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
200 Value *DD = A == C ? D : C;
201 // Form "A op' (B op DD)" if it simplifies completely.
202 // Does "B op DD" simplify?
203 if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, TLI, DT, MaxRecurse)) {
204 // It does! Return "A op' V" if it simplifies or is already available.
205 // If V equals B then "A op' V" is just the LHS. If V equals DD then
206 // "A op' V" is just the RHS.
207 if (V == B || V == DD) {
209 return V == B ? LHS : RHS;
211 // Otherwise return "A op' V" if it simplifies.
212 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, TLI, DT,
220 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
221 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
222 // commutative case, "(A op' B) op (B op' D)"?
223 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
224 Value *CC = B == D ? C : D;
225 // Form "(A op CC) op' B" if it simplifies completely..
226 // Does "A op CC" simplify?
227 if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, TLI, DT, MaxRecurse)) {
228 // It does! Return "V op' B" if it simplifies or is already available.
229 // If V equals A then "V op' B" is just the LHS. If V equals CC then
230 // "V op' B" is just the RHS.
231 if (V == A || V == CC) {
233 return V == A ? LHS : RHS;
235 // Otherwise return "V op' B" if it simplifies.
236 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, TLI, DT,
247 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
248 /// operations. Returns the simpler value, or null if none was found.
249 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
250 const TargetData *TD,
251 const TargetLibraryInfo *TLI,
252 const DominatorTree *DT,
253 unsigned MaxRecurse) {
254 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
255 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
257 // Recursion is always used, so bail out at once if we already hit the limit.
261 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
262 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
264 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
265 if (Op0 && Op0->getOpcode() == Opcode) {
266 Value *A = Op0->getOperand(0);
267 Value *B = Op0->getOperand(1);
270 // Does "B op C" simplify?
271 if (Value *V = SimplifyBinOp(Opcode, B, C, TD, TLI, DT, MaxRecurse)) {
272 // It does! Return "A op V" if it simplifies or is already available.
273 // If V equals B then "A op V" is just the LHS.
274 if (V == B) return LHS;
275 // Otherwise return "A op V" if it simplifies.
276 if (Value *W = SimplifyBinOp(Opcode, A, V, TD, TLI, DT, MaxRecurse)) {
283 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
284 if (Op1 && Op1->getOpcode() == Opcode) {
286 Value *B = Op1->getOperand(0);
287 Value *C = Op1->getOperand(1);
289 // Does "A op B" simplify?
290 if (Value *V = SimplifyBinOp(Opcode, A, B, TD, TLI, DT, MaxRecurse)) {
291 // It does! Return "V op C" if it simplifies or is already available.
292 // If V equals B then "V op C" is just the RHS.
293 if (V == B) return RHS;
294 // Otherwise return "V op C" if it simplifies.
295 if (Value *W = SimplifyBinOp(Opcode, V, C, TD, TLI, DT, MaxRecurse)) {
302 // The remaining transforms require commutativity as well as associativity.
303 if (!Instruction::isCommutative(Opcode))
306 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
307 if (Op0 && Op0->getOpcode() == Opcode) {
308 Value *A = Op0->getOperand(0);
309 Value *B = Op0->getOperand(1);
312 // Does "C op A" simplify?
313 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, TLI, DT, MaxRecurse)) {
314 // It does! Return "V op B" if it simplifies or is already available.
315 // If V equals A then "V op B" is just the LHS.
316 if (V == A) return LHS;
317 // Otherwise return "V op B" if it simplifies.
318 if (Value *W = SimplifyBinOp(Opcode, V, B, TD, TLI, DT, MaxRecurse)) {
325 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
326 if (Op1 && Op1->getOpcode() == Opcode) {
328 Value *B = Op1->getOperand(0);
329 Value *C = Op1->getOperand(1);
331 // Does "C op A" simplify?
332 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, TLI, DT, MaxRecurse)) {
333 // It does! Return "B op V" if it simplifies or is already available.
334 // If V equals C then "B op V" is just the RHS.
335 if (V == C) return RHS;
336 // Otherwise return "B op V" if it simplifies.
337 if (Value *W = SimplifyBinOp(Opcode, B, V, TD, TLI, DT, MaxRecurse)) {
347 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
348 /// instruction as an operand, try to simplify the binop by seeing whether
349 /// evaluating it on both branches of the select results in the same value.
350 /// Returns the common value if so, otherwise returns null.
351 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
352 const TargetData *TD,
353 const TargetLibraryInfo *TLI,
354 const DominatorTree *DT,
355 unsigned MaxRecurse) {
356 // Recursion is always used, so bail out at once if we already hit the limit.
361 if (isa<SelectInst>(LHS)) {
362 SI = cast<SelectInst>(LHS);
364 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
365 SI = cast<SelectInst>(RHS);
368 // Evaluate the BinOp on the true and false branches of the select.
372 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, TLI, DT, MaxRecurse);
373 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, TLI, DT, MaxRecurse);
375 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, TLI, DT, MaxRecurse);
376 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, TLI, DT, MaxRecurse);
379 // If they simplified to the same value, then return the common value.
380 // If they both failed to simplify then return null.
384 // If one branch simplified to undef, return the other one.
385 if (TV && isa<UndefValue>(TV))
387 if (FV && isa<UndefValue>(FV))
390 // If applying the operation did not change the true and false select values,
391 // then the result of the binop is the select itself.
392 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
395 // If one branch simplified and the other did not, and the simplified
396 // value is equal to the unsimplified one, return the simplified value.
397 // For example, select (cond, X, X & Z) & Z -> X & Z.
398 if ((FV && !TV) || (TV && !FV)) {
399 // Check that the simplified value has the form "X op Y" where "op" is the
400 // same as the original operation.
401 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
402 if (Simplified && Simplified->getOpcode() == Opcode) {
403 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
404 // We already know that "op" is the same as for the simplified value. See
405 // if the operands match too. If so, return the simplified value.
406 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
407 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
408 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
409 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
410 Simplified->getOperand(1) == UnsimplifiedRHS)
412 if (Simplified->isCommutative() &&
413 Simplified->getOperand(1) == UnsimplifiedLHS &&
414 Simplified->getOperand(0) == UnsimplifiedRHS)
422 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
423 /// try to simplify the comparison by seeing whether both branches of the select
424 /// result in the same value. Returns the common value if so, otherwise returns
426 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
427 Value *RHS, const TargetData *TD,
428 const TargetLibraryInfo *TLI,
429 const DominatorTree *DT,
430 unsigned MaxRecurse) {
431 // Recursion is always used, so bail out at once if we already hit the limit.
435 // Make sure the select is on the LHS.
436 if (!isa<SelectInst>(LHS)) {
438 Pred = CmpInst::getSwappedPredicate(Pred);
440 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
441 SelectInst *SI = cast<SelectInst>(LHS);
442 Value *Cond = SI->getCondition();
443 Value *TV = SI->getTrueValue();
444 Value *FV = SI->getFalseValue();
446 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
447 // Does "cmp TV, RHS" simplify?
448 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, TD, TLI, DT, MaxRecurse);
450 // It not only simplified, it simplified to the select condition. Replace
452 TCmp = getTrue(Cond->getType());
454 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
455 // condition then we can replace it with 'true'. Otherwise give up.
456 if (!isSameCompare(Cond, Pred, TV, RHS))
458 TCmp = getTrue(Cond->getType());
461 // Does "cmp FV, RHS" simplify?
462 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, TD, TLI, DT, MaxRecurse);
464 // It not only simplified, it simplified to the select condition. Replace
466 FCmp = getFalse(Cond->getType());
468 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
469 // condition then we can replace it with 'false'. Otherwise give up.
470 if (!isSameCompare(Cond, Pred, FV, RHS))
472 FCmp = getFalse(Cond->getType());
475 // If both sides simplified to the same value, then use it as the result of
476 // the original comparison.
480 // The remaining cases only make sense if the select condition has the same
481 // type as the result of the comparison, so bail out if this is not so.
482 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
484 // If the false value simplified to false, then the result of the compare
485 // is equal to "Cond && TCmp". This also catches the case when the false
486 // value simplified to false and the true value to true, returning "Cond".
487 if (match(FCmp, m_Zero()))
488 if (Value *V = SimplifyAndInst(Cond, TCmp, TD, TLI, DT, MaxRecurse))
490 // If the true value simplified to true, then the result of the compare
491 // is equal to "Cond || FCmp".
492 if (match(TCmp, m_One()))
493 if (Value *V = SimplifyOrInst(Cond, FCmp, TD, TLI, DT, MaxRecurse))
495 // Finally, if the false value simplified to true and the true value to
496 // false, then the result of the compare is equal to "!Cond".
497 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
499 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
500 TD, TLI, DT, MaxRecurse))
506 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
507 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
508 /// it on the incoming phi values yields the same result for every value. If so
509 /// returns the common value, otherwise returns null.
510 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
511 const TargetData *TD,
512 const TargetLibraryInfo *TLI,
513 const DominatorTree *DT,
514 unsigned MaxRecurse) {
515 // Recursion is always used, so bail out at once if we already hit the limit.
520 if (isa<PHINode>(LHS)) {
521 PI = cast<PHINode>(LHS);
522 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
523 if (!ValueDominatesPHI(RHS, PI, DT))
526 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
527 PI = cast<PHINode>(RHS);
528 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
529 if (!ValueDominatesPHI(LHS, PI, DT))
533 // Evaluate the BinOp on the incoming phi values.
534 Value *CommonValue = 0;
535 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
536 Value *Incoming = PI->getIncomingValue(i);
537 // If the incoming value is the phi node itself, it can safely be skipped.
538 if (Incoming == PI) continue;
539 Value *V = PI == LHS ?
540 SimplifyBinOp(Opcode, Incoming, RHS, TD, TLI, DT, MaxRecurse) :
541 SimplifyBinOp(Opcode, LHS, Incoming, TD, TLI, DT, MaxRecurse);
542 // If the operation failed to simplify, or simplified to a different value
543 // to previously, then give up.
544 if (!V || (CommonValue && V != CommonValue))
552 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
553 /// try to simplify the comparison by seeing whether comparing with all of the
554 /// incoming phi values yields the same result every time. If so returns the
555 /// common result, otherwise returns null.
556 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
557 const TargetData *TD,
558 const TargetLibraryInfo *TLI,
559 const DominatorTree *DT,
560 unsigned MaxRecurse) {
561 // Recursion is always used, so bail out at once if we already hit the limit.
565 // Make sure the phi is on the LHS.
566 if (!isa<PHINode>(LHS)) {
568 Pred = CmpInst::getSwappedPredicate(Pred);
570 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
571 PHINode *PI = cast<PHINode>(LHS);
573 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
574 if (!ValueDominatesPHI(RHS, PI, DT))
577 // Evaluate the BinOp on the incoming phi values.
578 Value *CommonValue = 0;
579 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
580 Value *Incoming = PI->getIncomingValue(i);
581 // If the incoming value is the phi node itself, it can safely be skipped.
582 if (Incoming == PI) continue;
583 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, TLI, DT, MaxRecurse);
584 // If the operation failed to simplify, or simplified to a different value
585 // to previously, then give up.
586 if (!V || (CommonValue && V != CommonValue))
594 /// SimplifyAddInst - Given operands for an Add, see if we can
595 /// fold the result. If not, this returns null.
596 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
597 const TargetData *TD,
598 const TargetLibraryInfo *TLI,
599 const DominatorTree *DT,
600 unsigned MaxRecurse) {
601 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
602 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
603 Constant *Ops[] = { CLHS, CRHS };
604 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
608 // Canonicalize the constant to the RHS.
612 // X + undef -> undef
613 if (match(Op1, m_Undef()))
617 if (match(Op1, m_Zero()))
624 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
625 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
628 // X + ~X -> -1 since ~X = -X-1
629 if (match(Op0, m_Not(m_Specific(Op1))) ||
630 match(Op1, m_Not(m_Specific(Op0))))
631 return Constant::getAllOnesValue(Op0->getType());
634 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
635 if (Value *V = SimplifyXorInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
638 // Try some generic simplifications for associative operations.
639 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, TLI, DT,
643 // Mul distributes over Add. Try some generic simplifications based on this.
644 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
645 TD, TLI, DT, MaxRecurse))
648 // Threading Add over selects and phi nodes is pointless, so don't bother.
649 // Threading over the select in "A + select(cond, B, C)" means evaluating
650 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
651 // only if B and C are equal. If B and C are equal then (since we assume
652 // that operands have already been simplified) "select(cond, B, C)" should
653 // have been simplified to the common value of B and C already. Analysing
654 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
655 // for threading over phi nodes.
660 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
661 const TargetData *TD, const TargetLibraryInfo *TLI,
662 const DominatorTree *DT) {
663 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
666 /// SimplifySubInst - Given operands for a Sub, see if we can
667 /// fold the result. If not, this returns null.
668 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
669 const TargetData *TD,
670 const TargetLibraryInfo *TLI,
671 const DominatorTree *DT,
672 unsigned MaxRecurse) {
673 if (Constant *CLHS = dyn_cast<Constant>(Op0))
674 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
675 Constant *Ops[] = { CLHS, CRHS };
676 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
680 // X - undef -> undef
681 // undef - X -> undef
682 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
683 return UndefValue::get(Op0->getType());
686 if (match(Op1, m_Zero()))
691 return Constant::getNullValue(Op0->getType());
696 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
697 match(Op0, m_Shl(m_Specific(Op1), m_One())))
700 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
701 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
702 Value *Y = 0, *Z = Op1;
703 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
704 // See if "V === Y - Z" simplifies.
705 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, TLI, DT, MaxRecurse-1))
706 // It does! Now see if "X + V" simplifies.
707 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, TLI, DT,
709 // It does, we successfully reassociated!
713 // See if "V === X - Z" simplifies.
714 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, TLI, DT, MaxRecurse-1))
715 // It does! Now see if "Y + V" simplifies.
716 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, TLI, DT,
718 // It does, we successfully reassociated!
724 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
725 // For example, X - (X + 1) -> -1
727 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
728 // See if "V === X - Y" simplifies.
729 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, TLI, DT, MaxRecurse-1))
730 // It does! Now see if "V - Z" simplifies.
731 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, TLI, DT,
733 // It does, we successfully reassociated!
737 // See if "V === X - Z" simplifies.
738 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, TLI, DT, MaxRecurse-1))
739 // It does! Now see if "V - Y" simplifies.
740 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, TLI, DT,
742 // It does, we successfully reassociated!
748 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
749 // For example, X - (X - Y) -> Y.
751 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
752 // See if "V === Z - X" simplifies.
753 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, TLI, DT, MaxRecurse-1))
754 // It does! Now see if "V + Y" simplifies.
755 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, TLI, DT,
757 // It does, we successfully reassociated!
762 // Mul distributes over Sub. Try some generic simplifications based on this.
763 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
764 TD, TLI, DT, MaxRecurse))
768 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
769 if (Value *V = SimplifyXorInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
772 // Threading Sub over selects and phi nodes is pointless, so don't bother.
773 // Threading over the select in "A - select(cond, B, C)" means evaluating
774 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
775 // only if B and C are equal. If B and C are equal then (since we assume
776 // that operands have already been simplified) "select(cond, B, C)" should
777 // have been simplified to the common value of B and C already. Analysing
778 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
779 // for threading over phi nodes.
784 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
785 const TargetData *TD,
786 const TargetLibraryInfo *TLI,
787 const DominatorTree *DT) {
788 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
791 /// SimplifyMulInst - Given operands for a Mul, see if we can
792 /// fold the result. If not, this returns null.
793 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
794 const TargetLibraryInfo *TLI,
795 const DominatorTree *DT, unsigned MaxRecurse) {
796 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
797 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
798 Constant *Ops[] = { CLHS, CRHS };
799 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
803 // Canonicalize the constant to the RHS.
808 if (match(Op1, m_Undef()))
809 return Constant::getNullValue(Op0->getType());
812 if (match(Op1, m_Zero()))
816 if (match(Op1, m_One()))
819 // (X / Y) * Y -> X if the division is exact.
821 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
822 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
826 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
827 if (Value *V = SimplifyAndInst(Op0, Op1, TD, TLI, DT, MaxRecurse-1))
830 // Try some generic simplifications for associative operations.
831 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, TLI, DT,
835 // Mul distributes over Add. Try some generic simplifications based on this.
836 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
837 TD, TLI, DT, MaxRecurse))
840 // If the operation is with the result of a select instruction, check whether
841 // operating on either branch of the select always yields the same value.
842 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
843 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, TLI, DT,
847 // If the operation is with the result of a phi instruction, check whether
848 // operating on all incoming values of the phi always yields the same value.
849 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
850 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, TLI, DT,
857 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
858 const TargetLibraryInfo *TLI,
859 const DominatorTree *DT) {
860 return ::SimplifyMulInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
863 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
864 /// fold the result. If not, this returns null.
865 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
866 const TargetData *TD, const TargetLibraryInfo *TLI,
867 const DominatorTree *DT, unsigned MaxRecurse) {
868 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
869 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
870 Constant *Ops[] = { C0, C1 };
871 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
875 bool isSigned = Opcode == Instruction::SDiv;
877 // X / undef -> undef
878 if (match(Op1, m_Undef()))
882 if (match(Op0, m_Undef()))
883 return Constant::getNullValue(Op0->getType());
885 // 0 / X -> 0, we don't need to preserve faults!
886 if (match(Op0, m_Zero()))
890 if (match(Op1, m_One()))
893 if (Op0->getType()->isIntegerTy(1))
894 // It can't be division by zero, hence it must be division by one.
899 return ConstantInt::get(Op0->getType(), 1);
901 // (X * Y) / Y -> X if the multiplication does not overflow.
902 Value *X = 0, *Y = 0;
903 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
904 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
905 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
906 // If the Mul knows it does not overflow, then we are good to go.
907 if ((isSigned && Mul->hasNoSignedWrap()) ||
908 (!isSigned && Mul->hasNoUnsignedWrap()))
910 // If X has the form X = A / Y then X * Y cannot overflow.
911 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
912 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
916 // (X rem Y) / Y -> 0
917 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
918 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
919 return Constant::getNullValue(Op0->getType());
921 // If the operation is with the result of a select instruction, check whether
922 // operating on either branch of the select always yields the same value.
923 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
924 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT,
928 // If the operation is with the result of a phi instruction, check whether
929 // operating on all incoming values of the phi always yields the same value.
930 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
931 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT,
938 /// SimplifySDivInst - Given operands for an SDiv, see if we can
939 /// fold the result. If not, this returns null.
940 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
941 const TargetLibraryInfo *TLI,
942 const DominatorTree *DT, unsigned MaxRecurse) {
943 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, TLI, DT,
950 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
951 const TargetLibraryInfo *TLI,
952 const DominatorTree *DT) {
953 return ::SimplifySDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
956 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
957 /// fold the result. If not, this returns null.
958 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
959 const TargetLibraryInfo *TLI,
960 const DominatorTree *DT, unsigned MaxRecurse) {
961 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, TLI, DT,
968 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
969 const TargetLibraryInfo *TLI,
970 const DominatorTree *DT) {
971 return ::SimplifyUDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
974 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *,
975 const TargetLibraryInfo *,
976 const DominatorTree *, unsigned) {
977 // undef / X -> undef (the undef could be a snan).
978 if (match(Op0, m_Undef()))
981 // X / undef -> undef
982 if (match(Op1, m_Undef()))
988 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
989 const TargetLibraryInfo *TLI,
990 const DominatorTree *DT) {
991 return ::SimplifyFDivInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
994 /// SimplifyRem - Given operands for an SRem or URem, see if we can
995 /// fold the result. If not, this returns null.
996 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
997 const TargetData *TD, const TargetLibraryInfo *TLI,
998 const DominatorTree *DT, unsigned MaxRecurse) {
999 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1000 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1001 Constant *Ops[] = { C0, C1 };
1002 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
1006 // X % undef -> undef
1007 if (match(Op1, m_Undef()))
1011 if (match(Op0, m_Undef()))
1012 return Constant::getNullValue(Op0->getType());
1014 // 0 % X -> 0, we don't need to preserve faults!
1015 if (match(Op0, m_Zero()))
1018 // X % 0 -> undef, we don't need to preserve faults!
1019 if (match(Op1, m_Zero()))
1020 return UndefValue::get(Op0->getType());
1023 if (match(Op1, m_One()))
1024 return Constant::getNullValue(Op0->getType());
1026 if (Op0->getType()->isIntegerTy(1))
1027 // It can't be remainder by zero, hence it must be remainder by one.
1028 return Constant::getNullValue(Op0->getType());
1032 return Constant::getNullValue(Op0->getType());
1034 // If the operation is with the result of a select instruction, check whether
1035 // operating on either branch of the select always yields the same value.
1036 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1037 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1040 // If the operation is with the result of a phi instruction, check whether
1041 // operating on all incoming values of the phi always yields the same value.
1042 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1043 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1049 /// SimplifySRemInst - Given operands for an SRem, see if we can
1050 /// fold the result. If not, this returns null.
1051 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1052 const TargetLibraryInfo *TLI,
1053 const DominatorTree *DT,
1054 unsigned MaxRecurse) {
1055 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, TD, TLI, DT, MaxRecurse))
1061 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1062 const TargetLibraryInfo *TLI,
1063 const DominatorTree *DT) {
1064 return ::SimplifySRemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1067 /// SimplifyURemInst - Given operands for a URem, see if we can
1068 /// fold the result. If not, this returns null.
1069 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1070 const TargetLibraryInfo *TLI,
1071 const DominatorTree *DT,
1072 unsigned MaxRecurse) {
1073 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, TD, TLI, DT, MaxRecurse))
1079 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1080 const TargetLibraryInfo *TLI,
1081 const DominatorTree *DT) {
1082 return ::SimplifyURemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1085 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *,
1086 const TargetLibraryInfo *,
1087 const DominatorTree *,
1089 // undef % X -> undef (the undef could be a snan).
1090 if (match(Op0, m_Undef()))
1093 // X % undef -> undef
1094 if (match(Op1, m_Undef()))
1100 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1101 const TargetLibraryInfo *TLI,
1102 const DominatorTree *DT) {
1103 return ::SimplifyFRemInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1106 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1107 /// fold the result. If not, this returns null.
1108 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1109 const TargetData *TD, const TargetLibraryInfo *TLI,
1110 const DominatorTree *DT, unsigned MaxRecurse) {
1111 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1112 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1113 Constant *Ops[] = { C0, C1 };
1114 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, TD, TLI);
1118 // 0 shift by X -> 0
1119 if (match(Op0, m_Zero()))
1122 // X shift by 0 -> X
1123 if (match(Op1, m_Zero()))
1126 // X shift by undef -> undef because it may shift by the bitwidth.
1127 if (match(Op1, m_Undef()))
1130 // Shifting by the bitwidth or more is undefined.
1131 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
1132 if (CI->getValue().getLimitedValue() >=
1133 Op0->getType()->getScalarSizeInBits())
1134 return UndefValue::get(Op0->getType());
1136 // If the operation is with the result of a select instruction, check whether
1137 // operating on either branch of the select always yields the same value.
1138 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1139 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1142 // If the operation is with the result of a phi instruction, check whether
1143 // operating on all incoming values of the phi always yields the same value.
1144 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1145 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, TLI, DT, MaxRecurse))
1151 /// SimplifyShlInst - Given operands for an Shl, see if we can
1152 /// fold the result. If not, this returns null.
1153 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1154 const TargetData *TD,
1155 const TargetLibraryInfo *TLI,
1156 const DominatorTree *DT, unsigned MaxRecurse) {
1157 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, TLI, DT, MaxRecurse))
1161 if (match(Op0, m_Undef()))
1162 return Constant::getNullValue(Op0->getType());
1164 // (X >> A) << A -> X
1166 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1171 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1172 const TargetData *TD, const TargetLibraryInfo *TLI,
1173 const DominatorTree *DT) {
1174 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, TD, TLI, DT, RecursionLimit);
1177 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1178 /// fold the result. If not, this returns null.
1179 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1180 const TargetData *TD,
1181 const TargetLibraryInfo *TLI,
1182 const DominatorTree *DT,
1183 unsigned MaxRecurse) {
1184 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, TLI, DT, MaxRecurse))
1188 if (match(Op0, m_Undef()))
1189 return Constant::getNullValue(Op0->getType());
1191 // (X << A) >> A -> X
1193 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1194 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
1200 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1201 const TargetData *TD,
1202 const TargetLibraryInfo *TLI,
1203 const DominatorTree *DT) {
1204 return ::SimplifyLShrInst(Op0, Op1, isExact, TD, TLI, DT, RecursionLimit);
1207 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1208 /// fold the result. If not, this returns null.
1209 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1210 const TargetData *TD,
1211 const TargetLibraryInfo *TLI,
1212 const DominatorTree *DT,
1213 unsigned MaxRecurse) {
1214 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, TLI, DT, MaxRecurse))
1217 // all ones >>a X -> all ones
1218 if (match(Op0, m_AllOnes()))
1221 // undef >>a X -> all ones
1222 if (match(Op0, m_Undef()))
1223 return Constant::getAllOnesValue(Op0->getType());
1225 // (X << A) >> A -> X
1227 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1228 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
1234 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1235 const TargetData *TD,
1236 const TargetLibraryInfo *TLI,
1237 const DominatorTree *DT) {
1238 return ::SimplifyAShrInst(Op0, Op1, isExact, TD, TLI, DT, RecursionLimit);
1241 /// SimplifyAndInst - Given operands for an And, see if we can
1242 /// fold the result. If not, this returns null.
1243 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1244 const TargetLibraryInfo *TLI,
1245 const DominatorTree *DT,
1246 unsigned MaxRecurse) {
1247 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1248 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1249 Constant *Ops[] = { CLHS, CRHS };
1250 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1254 // Canonicalize the constant to the RHS.
1255 std::swap(Op0, Op1);
1259 if (match(Op1, m_Undef()))
1260 return Constant::getNullValue(Op0->getType());
1267 if (match(Op1, m_Zero()))
1271 if (match(Op1, m_AllOnes()))
1274 // A & ~A = ~A & A = 0
1275 if (match(Op0, m_Not(m_Specific(Op1))) ||
1276 match(Op1, m_Not(m_Specific(Op0))))
1277 return Constant::getNullValue(Op0->getType());
1280 Value *A = 0, *B = 0;
1281 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1282 (A == Op1 || B == Op1))
1286 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1287 (A == Op0 || B == Op0))
1290 // A & (-A) = A if A is a power of two or zero.
1291 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1292 match(Op1, m_Neg(m_Specific(Op0)))) {
1293 if (isPowerOfTwo(Op0, TD, /*OrZero*/true))
1295 if (isPowerOfTwo(Op1, TD, /*OrZero*/true))
1299 // Try some generic simplifications for associative operations.
1300 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, TLI,
1304 // And distributes over Or. Try some generic simplifications based on this.
1305 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1306 TD, TLI, DT, MaxRecurse))
1309 // And distributes over Xor. Try some generic simplifications based on this.
1310 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1311 TD, TLI, DT, MaxRecurse))
1314 // Or distributes over And. Try some generic simplifications based on this.
1315 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1316 TD, TLI, DT, MaxRecurse))
1319 // If the operation is with the result of a select instruction, check whether
1320 // operating on either branch of the select always yields the same value.
1321 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1322 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, TLI,
1326 // If the operation is with the result of a phi instruction, check whether
1327 // operating on all incoming values of the phi always yields the same value.
1328 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1329 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, TLI, DT,
1336 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1337 const TargetLibraryInfo *TLI,
1338 const DominatorTree *DT) {
1339 return ::SimplifyAndInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1342 /// SimplifyOrInst - Given operands for an Or, see if we can
1343 /// fold the result. If not, this returns null.
1344 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1345 const TargetLibraryInfo *TLI,
1346 const DominatorTree *DT, unsigned MaxRecurse) {
1347 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1348 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1349 Constant *Ops[] = { CLHS, CRHS };
1350 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1354 // Canonicalize the constant to the RHS.
1355 std::swap(Op0, Op1);
1359 if (match(Op1, m_Undef()))
1360 return Constant::getAllOnesValue(Op0->getType());
1367 if (match(Op1, m_Zero()))
1371 if (match(Op1, m_AllOnes()))
1374 // A | ~A = ~A | A = -1
1375 if (match(Op0, m_Not(m_Specific(Op1))) ||
1376 match(Op1, m_Not(m_Specific(Op0))))
1377 return Constant::getAllOnesValue(Op0->getType());
1380 Value *A = 0, *B = 0;
1381 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1382 (A == Op1 || B == Op1))
1386 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1387 (A == Op0 || B == Op0))
1390 // ~(A & ?) | A = -1
1391 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1392 (A == Op1 || B == Op1))
1393 return Constant::getAllOnesValue(Op1->getType());
1395 // A | ~(A & ?) = -1
1396 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1397 (A == Op0 || B == Op0))
1398 return Constant::getAllOnesValue(Op0->getType());
1400 // Try some generic simplifications for associative operations.
1401 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, TLI,
1405 // Or distributes over And. Try some generic simplifications based on this.
1406 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, TD,
1407 TLI, DT, MaxRecurse))
1410 // And distributes over Or. Try some generic simplifications based on this.
1411 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1412 TD, TLI, DT, MaxRecurse))
1415 // If the operation is with the result of a select instruction, check whether
1416 // operating on either branch of the select always yields the same value.
1417 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1418 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, TLI, DT,
1422 // If the operation is with the result of a phi instruction, check whether
1423 // operating on all incoming values of the phi always yields the same value.
1424 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1425 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, TLI, DT,
1432 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1433 const TargetLibraryInfo *TLI,
1434 const DominatorTree *DT) {
1435 return ::SimplifyOrInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1438 /// SimplifyXorInst - Given operands for a Xor, see if we can
1439 /// fold the result. If not, this returns null.
1440 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1441 const TargetLibraryInfo *TLI,
1442 const DominatorTree *DT, unsigned MaxRecurse) {
1443 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1444 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1445 Constant *Ops[] = { CLHS, CRHS };
1446 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1450 // Canonicalize the constant to the RHS.
1451 std::swap(Op0, Op1);
1454 // A ^ undef -> undef
1455 if (match(Op1, m_Undef()))
1459 if (match(Op1, m_Zero()))
1464 return Constant::getNullValue(Op0->getType());
1466 // A ^ ~A = ~A ^ A = -1
1467 if (match(Op0, m_Not(m_Specific(Op1))) ||
1468 match(Op1, m_Not(m_Specific(Op0))))
1469 return Constant::getAllOnesValue(Op0->getType());
1471 // Try some generic simplifications for associative operations.
1472 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, TLI,
1476 // And distributes over Xor. Try some generic simplifications based on this.
1477 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1478 TD, TLI, DT, MaxRecurse))
1481 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1482 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1483 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1484 // only if B and C are equal. If B and C are equal then (since we assume
1485 // that operands have already been simplified) "select(cond, B, C)" should
1486 // have been simplified to the common value of B and C already. Analysing
1487 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1488 // for threading over phi nodes.
1493 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1494 const TargetLibraryInfo *TLI,
1495 const DominatorTree *DT) {
1496 return ::SimplifyXorInst(Op0, Op1, TD, TLI, DT, RecursionLimit);
1499 static Type *GetCompareTy(Value *Op) {
1500 return CmpInst::makeCmpResultType(Op->getType());
1503 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1504 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1505 /// otherwise return null. Helper function for analyzing max/min idioms.
1506 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1507 Value *LHS, Value *RHS) {
1508 SelectInst *SI = dyn_cast<SelectInst>(V);
1511 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1514 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1515 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1517 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1518 LHS == CmpRHS && RHS == CmpLHS)
1523 /// stripPointerAdjustments - This is like Value::stripPointerCasts, but also
1524 /// removes inbounds gep operations, regardless of their indices.
1525 static Value *stripPointerAdjustmentsImpl(Value *V,
1526 SmallPtrSet<GEPOperator*, 8> &VisitedGEPs) {
1527 GEPOperator *GEP = dyn_cast<GEPOperator>(V);
1528 if (GEP == 0 || !GEP->isInBounds())
1531 // If we've already seen this GEP, we will end up infinitely looping. This
1532 // can happen in unreachable code.
1533 if (!VisitedGEPs.insert(GEP))
1536 return stripPointerAdjustmentsImpl(GEP->getOperand(0)->stripPointerCasts(),
1540 static Value *stripPointerAdjustments(Value *V) {
1541 SmallPtrSet<GEPOperator*, 8> VisitedGEPs;
1542 return stripPointerAdjustmentsImpl(V, VisitedGEPs);
1546 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1547 /// fold the result. If not, this returns null.
1548 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1549 const TargetData *TD,
1550 const TargetLibraryInfo *TLI,
1551 const DominatorTree *DT,
1552 unsigned MaxRecurse) {
1553 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1554 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1556 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1557 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1558 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD, TLI);
1560 // If we have a constant, make sure it is on the RHS.
1561 std::swap(LHS, RHS);
1562 Pred = CmpInst::getSwappedPredicate(Pred);
1565 Type *ITy = GetCompareTy(LHS); // The return type.
1566 Type *OpTy = LHS->getType(); // The operand type.
1568 // icmp X, X -> true/false
1569 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1570 // because X could be 0.
1571 if (LHS == RHS || isa<UndefValue>(RHS))
1572 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1574 // Special case logic when the operands have i1 type.
1575 if (OpTy->getScalarType()->isIntegerTy(1)) {
1578 case ICmpInst::ICMP_EQ:
1580 if (match(RHS, m_One()))
1583 case ICmpInst::ICMP_NE:
1585 if (match(RHS, m_Zero()))
1588 case ICmpInst::ICMP_UGT:
1590 if (match(RHS, m_Zero()))
1593 case ICmpInst::ICMP_UGE:
1595 if (match(RHS, m_One()))
1598 case ICmpInst::ICMP_SLT:
1600 if (match(RHS, m_Zero()))
1603 case ICmpInst::ICMP_SLE:
1605 if (match(RHS, m_One()))
1611 // icmp <alloca*>, <global/alloca*/null> - Different stack variables have
1612 // different addresses, and what's more the address of a stack variable is
1613 // never null or equal to the address of a global. Note that generalizing
1614 // to the case where LHS is a global variable address or null is pointless,
1615 // since if both LHS and RHS are constants then we already constant folded
1616 // the compare, and if only one of them is then we moved it to RHS already.
1617 Value *LHSPtr = LHS->stripPointerCasts();
1618 Value *RHSPtr = RHS->stripPointerCasts();
1619 if (LHSPtr == RHSPtr)
1620 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1622 // Be more aggressive about stripping pointer adjustments when checking a
1623 // comparison of an alloca address to another object. We can rip off all
1624 // inbounds GEP operations, even if they are variable.
1625 LHSPtr = stripPointerAdjustments(LHSPtr);
1626 if (isa<AllocaInst>(LHSPtr)) {
1627 RHSPtr = stripPointerAdjustments(RHSPtr);
1628 if (LHSPtr != RHSPtr &&
1629 (isa<GlobalValue>(RHSPtr) || isa<AllocaInst>(RHSPtr) ||
1630 isa<ConstantPointerNull>(RHSPtr)))
1631 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
1634 // If we are comparing with zero then try hard since this is a common case.
1635 if (match(RHS, m_Zero())) {
1636 bool LHSKnownNonNegative, LHSKnownNegative;
1638 default: llvm_unreachable("Unknown ICmp predicate!");
1639 case ICmpInst::ICMP_ULT:
1640 return getFalse(ITy);
1641 case ICmpInst::ICMP_UGE:
1642 return getTrue(ITy);
1643 case ICmpInst::ICMP_EQ:
1644 case ICmpInst::ICMP_ULE:
1645 if (isKnownNonZero(LHS, TD))
1646 return getFalse(ITy);
1648 case ICmpInst::ICMP_NE:
1649 case ICmpInst::ICMP_UGT:
1650 if (isKnownNonZero(LHS, TD))
1651 return getTrue(ITy);
1653 case ICmpInst::ICMP_SLT:
1654 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1655 if (LHSKnownNegative)
1656 return getTrue(ITy);
1657 if (LHSKnownNonNegative)
1658 return getFalse(ITy);
1660 case ICmpInst::ICMP_SLE:
1661 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1662 if (LHSKnownNegative)
1663 return getTrue(ITy);
1664 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1665 return getFalse(ITy);
1667 case ICmpInst::ICMP_SGE:
1668 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1669 if (LHSKnownNegative)
1670 return getFalse(ITy);
1671 if (LHSKnownNonNegative)
1672 return getTrue(ITy);
1674 case ICmpInst::ICMP_SGT:
1675 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1676 if (LHSKnownNegative)
1677 return getFalse(ITy);
1678 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1679 return getTrue(ITy);
1684 // See if we are doing a comparison with a constant integer.
1685 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1686 // Rule out tautological comparisons (eg., ult 0 or uge 0).
1687 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
1688 if (RHS_CR.isEmptySet())
1689 return ConstantInt::getFalse(CI->getContext());
1690 if (RHS_CR.isFullSet())
1691 return ConstantInt::getTrue(CI->getContext());
1693 // Many binary operators with constant RHS have easy to compute constant
1694 // range. Use them to check whether the comparison is a tautology.
1695 uint32_t Width = CI->getBitWidth();
1696 APInt Lower = APInt(Width, 0);
1697 APInt Upper = APInt(Width, 0);
1699 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
1700 // 'urem x, CI2' produces [0, CI2).
1701 Upper = CI2->getValue();
1702 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
1703 // 'srem x, CI2' produces (-|CI2|, |CI2|).
1704 Upper = CI2->getValue().abs();
1705 Lower = (-Upper) + 1;
1706 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
1707 // 'udiv CI2, x' produces [0, CI2].
1708 Upper = CI2->getValue() + 1;
1709 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
1710 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
1711 APInt NegOne = APInt::getAllOnesValue(Width);
1713 Upper = NegOne.udiv(CI2->getValue()) + 1;
1714 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
1715 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
1716 APInt IntMin = APInt::getSignedMinValue(Width);
1717 APInt IntMax = APInt::getSignedMaxValue(Width);
1718 APInt Val = CI2->getValue().abs();
1719 if (!Val.isMinValue()) {
1720 Lower = IntMin.sdiv(Val);
1721 Upper = IntMax.sdiv(Val) + 1;
1723 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
1724 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
1725 APInt NegOne = APInt::getAllOnesValue(Width);
1726 if (CI2->getValue().ult(Width))
1727 Upper = NegOne.lshr(CI2->getValue()) + 1;
1728 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
1729 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
1730 APInt IntMin = APInt::getSignedMinValue(Width);
1731 APInt IntMax = APInt::getSignedMaxValue(Width);
1732 if (CI2->getValue().ult(Width)) {
1733 Lower = IntMin.ashr(CI2->getValue());
1734 Upper = IntMax.ashr(CI2->getValue()) + 1;
1736 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
1737 // 'or x, CI2' produces [CI2, UINT_MAX].
1738 Lower = CI2->getValue();
1739 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
1740 // 'and x, CI2' produces [0, CI2].
1741 Upper = CI2->getValue() + 1;
1743 if (Lower != Upper) {
1744 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
1745 if (RHS_CR.contains(LHS_CR))
1746 return ConstantInt::getTrue(RHS->getContext());
1747 if (RHS_CR.inverse().contains(LHS_CR))
1748 return ConstantInt::getFalse(RHS->getContext());
1752 // Compare of cast, for example (zext X) != 0 -> X != 0
1753 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1754 Instruction *LI = cast<CastInst>(LHS);
1755 Value *SrcOp = LI->getOperand(0);
1756 Type *SrcTy = SrcOp->getType();
1757 Type *DstTy = LI->getType();
1759 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1760 // if the integer type is the same size as the pointer type.
1761 if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
1762 TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1763 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1764 // Transfer the cast to the constant.
1765 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1766 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1767 TD, TLI, DT, MaxRecurse-1))
1769 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1770 if (RI->getOperand(0)->getType() == SrcTy)
1771 // Compare without the cast.
1772 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1773 TD, TLI, DT, MaxRecurse-1))
1778 if (isa<ZExtInst>(LHS)) {
1779 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1781 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1782 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1783 // Compare X and Y. Note that signed predicates become unsigned.
1784 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1785 SrcOp, RI->getOperand(0), TD, TLI, DT,
1789 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1790 // too. If not, then try to deduce the result of the comparison.
1791 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1792 // Compute the constant that would happen if we truncated to SrcTy then
1793 // reextended to DstTy.
1794 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1795 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1797 // If the re-extended constant didn't change then this is effectively
1798 // also a case of comparing two zero-extended values.
1799 if (RExt == CI && MaxRecurse)
1800 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1801 SrcOp, Trunc, TD, TLI, DT, MaxRecurse-1))
1804 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1805 // there. Use this to work out the result of the comparison.
1808 default: llvm_unreachable("Unknown ICmp predicate!");
1810 case ICmpInst::ICMP_EQ:
1811 case ICmpInst::ICMP_UGT:
1812 case ICmpInst::ICMP_UGE:
1813 return ConstantInt::getFalse(CI->getContext());
1815 case ICmpInst::ICMP_NE:
1816 case ICmpInst::ICMP_ULT:
1817 case ICmpInst::ICMP_ULE:
1818 return ConstantInt::getTrue(CI->getContext());
1820 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1821 // is non-negative then LHS <s RHS.
1822 case ICmpInst::ICMP_SGT:
1823 case ICmpInst::ICMP_SGE:
1824 return CI->getValue().isNegative() ?
1825 ConstantInt::getTrue(CI->getContext()) :
1826 ConstantInt::getFalse(CI->getContext());
1828 case ICmpInst::ICMP_SLT:
1829 case ICmpInst::ICMP_SLE:
1830 return CI->getValue().isNegative() ?
1831 ConstantInt::getFalse(CI->getContext()) :
1832 ConstantInt::getTrue(CI->getContext());
1838 if (isa<SExtInst>(LHS)) {
1839 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1841 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1842 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1843 // Compare X and Y. Note that the predicate does not change.
1844 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1845 TD, TLI, DT, MaxRecurse-1))
1848 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1849 // too. If not, then try to deduce the result of the comparison.
1850 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1851 // Compute the constant that would happen if we truncated to SrcTy then
1852 // reextended to DstTy.
1853 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1854 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1856 // If the re-extended constant didn't change then this is effectively
1857 // also a case of comparing two sign-extended values.
1858 if (RExt == CI && MaxRecurse)
1859 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, TLI, DT,
1863 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1864 // bits there. Use this to work out the result of the comparison.
1867 default: llvm_unreachable("Unknown ICmp predicate!");
1868 case ICmpInst::ICMP_EQ:
1869 return ConstantInt::getFalse(CI->getContext());
1870 case ICmpInst::ICMP_NE:
1871 return ConstantInt::getTrue(CI->getContext());
1873 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1875 case ICmpInst::ICMP_SGT:
1876 case ICmpInst::ICMP_SGE:
1877 return CI->getValue().isNegative() ?
1878 ConstantInt::getTrue(CI->getContext()) :
1879 ConstantInt::getFalse(CI->getContext());
1880 case ICmpInst::ICMP_SLT:
1881 case ICmpInst::ICMP_SLE:
1882 return CI->getValue().isNegative() ?
1883 ConstantInt::getFalse(CI->getContext()) :
1884 ConstantInt::getTrue(CI->getContext());
1886 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
1888 case ICmpInst::ICMP_UGT:
1889 case ICmpInst::ICMP_UGE:
1890 // Comparison is true iff the LHS <s 0.
1892 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
1893 Constant::getNullValue(SrcTy),
1894 TD, TLI, DT, MaxRecurse-1))
1897 case ICmpInst::ICMP_ULT:
1898 case ICmpInst::ICMP_ULE:
1899 // Comparison is true iff the LHS >=s 0.
1901 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
1902 Constant::getNullValue(SrcTy),
1903 TD, TLI, DT, MaxRecurse-1))
1912 // Special logic for binary operators.
1913 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
1914 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
1915 if (MaxRecurse && (LBO || RBO)) {
1916 // Analyze the case when either LHS or RHS is an add instruction.
1917 Value *A = 0, *B = 0, *C = 0, *D = 0;
1918 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
1919 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
1920 if (LBO && LBO->getOpcode() == Instruction::Add) {
1921 A = LBO->getOperand(0); B = LBO->getOperand(1);
1922 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
1923 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
1924 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
1926 if (RBO && RBO->getOpcode() == Instruction::Add) {
1927 C = RBO->getOperand(0); D = RBO->getOperand(1);
1928 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
1929 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
1930 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
1933 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
1934 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
1935 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
1936 Constant::getNullValue(RHS->getType()),
1937 TD, TLI, DT, MaxRecurse-1))
1940 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
1941 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
1942 if (Value *V = SimplifyICmpInst(Pred,
1943 Constant::getNullValue(LHS->getType()),
1944 C == LHS ? D : C, TD, TLI, DT, MaxRecurse-1))
1947 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
1948 if (A && C && (A == C || A == D || B == C || B == D) &&
1949 NoLHSWrapProblem && NoRHSWrapProblem) {
1950 // Determine Y and Z in the form icmp (X+Y), (X+Z).
1951 Value *Y = (A == C || A == D) ? B : A;
1952 Value *Z = (C == A || C == B) ? D : C;
1953 if (Value *V = SimplifyICmpInst(Pred, Y, Z, TD, TLI, DT, MaxRecurse-1))
1958 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
1959 bool KnownNonNegative, KnownNegative;
1963 case ICmpInst::ICMP_SGT:
1964 case ICmpInst::ICMP_SGE:
1965 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD);
1966 if (!KnownNonNegative)
1969 case ICmpInst::ICMP_EQ:
1970 case ICmpInst::ICMP_UGT:
1971 case ICmpInst::ICMP_UGE:
1972 return getFalse(ITy);
1973 case ICmpInst::ICMP_SLT:
1974 case ICmpInst::ICMP_SLE:
1975 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD);
1976 if (!KnownNonNegative)
1979 case ICmpInst::ICMP_NE:
1980 case ICmpInst::ICMP_ULT:
1981 case ICmpInst::ICMP_ULE:
1982 return getTrue(ITy);
1985 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
1986 bool KnownNonNegative, KnownNegative;
1990 case ICmpInst::ICMP_SGT:
1991 case ICmpInst::ICMP_SGE:
1992 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD);
1993 if (!KnownNonNegative)
1996 case ICmpInst::ICMP_NE:
1997 case ICmpInst::ICMP_UGT:
1998 case ICmpInst::ICMP_UGE:
1999 return getTrue(ITy);
2000 case ICmpInst::ICMP_SLT:
2001 case ICmpInst::ICMP_SLE:
2002 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD);
2003 if (!KnownNonNegative)
2006 case ICmpInst::ICMP_EQ:
2007 case ICmpInst::ICMP_ULT:
2008 case ICmpInst::ICMP_ULE:
2009 return getFalse(ITy);
2014 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2015 // icmp pred (X /u Y), X
2016 if (Pred == ICmpInst::ICMP_UGT)
2017 return getFalse(ITy);
2018 if (Pred == ICmpInst::ICMP_ULE)
2019 return getTrue(ITy);
2022 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2023 LBO->getOperand(1) == RBO->getOperand(1)) {
2024 switch (LBO->getOpcode()) {
2026 case Instruction::UDiv:
2027 case Instruction::LShr:
2028 if (ICmpInst::isSigned(Pred))
2031 case Instruction::SDiv:
2032 case Instruction::AShr:
2033 if (!LBO->isExact() || !RBO->isExact())
2035 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2036 RBO->getOperand(0), TD, TLI, DT, MaxRecurse-1))
2039 case Instruction::Shl: {
2040 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2041 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2044 if (!NSW && ICmpInst::isSigned(Pred))
2046 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2047 RBO->getOperand(0), TD, TLI, DT, MaxRecurse-1))
2054 // Simplify comparisons involving max/min.
2056 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2057 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2059 // Signed variants on "max(a,b)>=a -> true".
2060 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2061 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2062 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2063 // We analyze this as smax(A, B) pred A.
2065 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2066 (A == LHS || B == LHS)) {
2067 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2068 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2069 // We analyze this as smax(A, B) swapped-pred A.
2070 P = CmpInst::getSwappedPredicate(Pred);
2071 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2072 (A == RHS || B == RHS)) {
2073 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2074 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2075 // We analyze this as smax(-A, -B) swapped-pred -A.
2076 // Note that we do not need to actually form -A or -B thanks to EqP.
2077 P = CmpInst::getSwappedPredicate(Pred);
2078 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2079 (A == LHS || B == LHS)) {
2080 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2081 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2082 // We analyze this as smax(-A, -B) pred -A.
2083 // Note that we do not need to actually form -A or -B thanks to EqP.
2086 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2087 // Cases correspond to "max(A, B) p A".
2091 case CmpInst::ICMP_EQ:
2092 case CmpInst::ICMP_SLE:
2093 // Equivalent to "A EqP B". This may be the same as the condition tested
2094 // in the max/min; if so, we can just return that.
2095 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2097 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2099 // Otherwise, see if "A EqP B" simplifies.
2101 if (Value *V = SimplifyICmpInst(EqP, A, B, TD, TLI, DT, MaxRecurse-1))
2104 case CmpInst::ICMP_NE:
2105 case CmpInst::ICMP_SGT: {
2106 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2107 // Equivalent to "A InvEqP B". This may be the same as the condition
2108 // tested in the max/min; if so, we can just return that.
2109 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2111 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2113 // Otherwise, see if "A InvEqP B" simplifies.
2115 if (Value *V = SimplifyICmpInst(InvEqP, A, B, TD, TLI, DT, MaxRecurse-1))
2119 case CmpInst::ICMP_SGE:
2121 return getTrue(ITy);
2122 case CmpInst::ICMP_SLT:
2124 return getFalse(ITy);
2128 // Unsigned variants on "max(a,b)>=a -> true".
2129 P = CmpInst::BAD_ICMP_PREDICATE;
2130 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2131 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2132 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2133 // We analyze this as umax(A, B) pred A.
2135 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2136 (A == LHS || B == LHS)) {
2137 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2138 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2139 // We analyze this as umax(A, B) swapped-pred A.
2140 P = CmpInst::getSwappedPredicate(Pred);
2141 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2142 (A == RHS || B == RHS)) {
2143 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2144 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2145 // We analyze this as umax(-A, -B) swapped-pred -A.
2146 // Note that we do not need to actually form -A or -B thanks to EqP.
2147 P = CmpInst::getSwappedPredicate(Pred);
2148 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2149 (A == LHS || B == LHS)) {
2150 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2151 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2152 // We analyze this as umax(-A, -B) pred -A.
2153 // Note that we do not need to actually form -A or -B thanks to EqP.
2156 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2157 // Cases correspond to "max(A, B) p A".
2161 case CmpInst::ICMP_EQ:
2162 case CmpInst::ICMP_ULE:
2163 // Equivalent to "A EqP B". This may be the same as the condition tested
2164 // in the max/min; if so, we can just return that.
2165 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2167 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2169 // Otherwise, see if "A EqP B" simplifies.
2171 if (Value *V = SimplifyICmpInst(EqP, A, B, TD, TLI, DT, MaxRecurse-1))
2174 case CmpInst::ICMP_NE:
2175 case CmpInst::ICMP_UGT: {
2176 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2177 // Equivalent to "A InvEqP B". This may be the same as the condition
2178 // tested in the max/min; if so, we can just return that.
2179 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2181 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2183 // Otherwise, see if "A InvEqP B" simplifies.
2185 if (Value *V = SimplifyICmpInst(InvEqP, A, B, TD, TLI, DT, MaxRecurse-1))
2189 case CmpInst::ICMP_UGE:
2191 return getTrue(ITy);
2192 case CmpInst::ICMP_ULT:
2194 return getFalse(ITy);
2198 // Variants on "max(x,y) >= min(x,z)".
2200 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2201 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2202 (A == C || A == D || B == C || B == D)) {
2203 // max(x, ?) pred min(x, ?).
2204 if (Pred == CmpInst::ICMP_SGE)
2206 return getTrue(ITy);
2207 if (Pred == CmpInst::ICMP_SLT)
2209 return getFalse(ITy);
2210 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2211 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2212 (A == C || A == D || B == C || B == D)) {
2213 // min(x, ?) pred max(x, ?).
2214 if (Pred == CmpInst::ICMP_SLE)
2216 return getTrue(ITy);
2217 if (Pred == CmpInst::ICMP_SGT)
2219 return getFalse(ITy);
2220 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2221 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2222 (A == C || A == D || B == C || B == D)) {
2223 // max(x, ?) pred min(x, ?).
2224 if (Pred == CmpInst::ICMP_UGE)
2226 return getTrue(ITy);
2227 if (Pred == CmpInst::ICMP_ULT)
2229 return getFalse(ITy);
2230 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2231 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2232 (A == C || A == D || B == C || B == D)) {
2233 // min(x, ?) pred max(x, ?).
2234 if (Pred == CmpInst::ICMP_ULE)
2236 return getTrue(ITy);
2237 if (Pred == CmpInst::ICMP_UGT)
2239 return getFalse(ITy);
2242 // If the comparison is with the result of a select instruction, check whether
2243 // comparing with either branch of the select always yields the same value.
2244 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2245 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2248 // If the comparison is with the result of a phi instruction, check whether
2249 // doing the compare with each incoming phi value yields a common result.
2250 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2251 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2257 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2258 const TargetData *TD,
2259 const TargetLibraryInfo *TLI,
2260 const DominatorTree *DT) {
2261 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2264 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
2265 /// fold the result. If not, this returns null.
2266 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2267 const TargetData *TD,
2268 const TargetLibraryInfo *TLI,
2269 const DominatorTree *DT,
2270 unsigned MaxRecurse) {
2271 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2272 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
2274 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2275 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2276 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD, TLI);
2278 // If we have a constant, make sure it is on the RHS.
2279 std::swap(LHS, RHS);
2280 Pred = CmpInst::getSwappedPredicate(Pred);
2283 // Fold trivial predicates.
2284 if (Pred == FCmpInst::FCMP_FALSE)
2285 return ConstantInt::get(GetCompareTy(LHS), 0);
2286 if (Pred == FCmpInst::FCMP_TRUE)
2287 return ConstantInt::get(GetCompareTy(LHS), 1);
2289 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
2290 return UndefValue::get(GetCompareTy(LHS));
2292 // fcmp x,x -> true/false. Not all compares are foldable.
2294 if (CmpInst::isTrueWhenEqual(Pred))
2295 return ConstantInt::get(GetCompareTy(LHS), 1);
2296 if (CmpInst::isFalseWhenEqual(Pred))
2297 return ConstantInt::get(GetCompareTy(LHS), 0);
2300 // Handle fcmp with constant RHS
2301 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2302 // If the constant is a nan, see if we can fold the comparison based on it.
2303 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2304 if (CFP->getValueAPF().isNaN()) {
2305 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
2306 return ConstantInt::getFalse(CFP->getContext());
2307 assert(FCmpInst::isUnordered(Pred) &&
2308 "Comparison must be either ordered or unordered!");
2309 // True if unordered.
2310 return ConstantInt::getTrue(CFP->getContext());
2312 // Check whether the constant is an infinity.
2313 if (CFP->getValueAPF().isInfinity()) {
2314 if (CFP->getValueAPF().isNegative()) {
2316 case FCmpInst::FCMP_OLT:
2317 // No value is ordered and less than negative infinity.
2318 return ConstantInt::getFalse(CFP->getContext());
2319 case FCmpInst::FCMP_UGE:
2320 // All values are unordered with or at least negative infinity.
2321 return ConstantInt::getTrue(CFP->getContext());
2327 case FCmpInst::FCMP_OGT:
2328 // No value is ordered and greater than infinity.
2329 return ConstantInt::getFalse(CFP->getContext());
2330 case FCmpInst::FCMP_ULE:
2331 // All values are unordered with and at most infinity.
2332 return ConstantInt::getTrue(CFP->getContext());
2341 // If the comparison is with the result of a select instruction, check whether
2342 // comparing with either branch of the select always yields the same value.
2343 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2344 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2347 // If the comparison is with the result of a phi instruction, check whether
2348 // doing the compare with each incoming phi value yields a common result.
2349 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2350 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, TLI, DT, MaxRecurse))
2356 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2357 const TargetData *TD,
2358 const TargetLibraryInfo *TLI,
2359 const DominatorTree *DT) {
2360 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2363 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
2364 /// the result. If not, this returns null.
2365 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
2366 const TargetData *TD, const DominatorTree *) {
2367 // select true, X, Y -> X
2368 // select false, X, Y -> Y
2369 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
2370 return CB->getZExtValue() ? TrueVal : FalseVal;
2372 // select C, X, X -> X
2373 if (TrueVal == FalseVal)
2376 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
2377 if (isa<Constant>(TrueVal))
2381 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
2383 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
2389 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
2390 /// fold the result. If not, this returns null.
2391 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const TargetData *TD,
2392 const DominatorTree *) {
2393 // The type of the GEP pointer operand.
2394 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType());
2395 // The GEP pointer operand is not a pointer, it's a vector of pointers.
2399 // getelementptr P -> P.
2400 if (Ops.size() == 1)
2403 if (isa<UndefValue>(Ops[0])) {
2404 // Compute the (pointer) type returned by the GEP instruction.
2405 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
2406 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
2407 return UndefValue::get(GEPTy);
2410 if (Ops.size() == 2) {
2411 // getelementptr P, 0 -> P.
2412 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
2415 // getelementptr P, N -> P if P points to a type of zero size.
2417 Type *Ty = PtrTy->getElementType();
2418 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
2423 // Check to see if this is constant foldable.
2424 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2425 if (!isa<Constant>(Ops[i]))
2428 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
2431 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
2432 /// can fold the result. If not, this returns null.
2433 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
2434 ArrayRef<unsigned> Idxs,
2436 const DominatorTree *) {
2437 if (Constant *CAgg = dyn_cast<Constant>(Agg))
2438 if (Constant *CVal = dyn_cast<Constant>(Val))
2439 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
2441 // insertvalue x, undef, n -> x
2442 if (match(Val, m_Undef()))
2445 // insertvalue x, (extractvalue y, n), n
2446 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
2447 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
2448 EV->getIndices() == Idxs) {
2449 // insertvalue undef, (extractvalue y, n), n -> y
2450 if (match(Agg, m_Undef()))
2451 return EV->getAggregateOperand();
2453 // insertvalue y, (extractvalue y, n), n -> y
2454 if (Agg == EV->getAggregateOperand())
2461 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
2462 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
2463 // If all of the PHI's incoming values are the same then replace the PHI node
2464 // with the common value.
2465 Value *CommonValue = 0;
2466 bool HasUndefInput = false;
2467 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
2468 Value *Incoming = PN->getIncomingValue(i);
2469 // If the incoming value is the phi node itself, it can safely be skipped.
2470 if (Incoming == PN) continue;
2471 if (isa<UndefValue>(Incoming)) {
2472 // Remember that we saw an undef value, but otherwise ignore them.
2473 HasUndefInput = true;
2476 if (CommonValue && Incoming != CommonValue)
2477 return 0; // Not the same, bail out.
2478 CommonValue = Incoming;
2481 // If CommonValue is null then all of the incoming values were either undef or
2482 // equal to the phi node itself.
2484 return UndefValue::get(PN->getType());
2486 // If we have a PHI node like phi(X, undef, X), where X is defined by some
2487 // instruction, we cannot return X as the result of the PHI node unless it
2488 // dominates the PHI block.
2490 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
2495 //=== Helper functions for higher up the class hierarchy.
2497 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
2498 /// fold the result. If not, this returns null.
2499 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2500 const TargetData *TD,
2501 const TargetLibraryInfo *TLI,
2502 const DominatorTree *DT,
2503 unsigned MaxRecurse) {
2505 case Instruction::Add:
2506 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2507 TD, TLI, DT, MaxRecurse);
2508 case Instruction::Sub:
2509 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2510 TD, TLI, DT, MaxRecurse);
2511 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, TD, TLI, DT,
2513 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, TLI, DT,
2515 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, TLI, DT,
2517 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, TLI, DT,
2519 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, TD, TLI, DT,
2521 case Instruction::URem: return SimplifyURemInst(LHS, RHS, TD, TLI, DT,
2523 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, TD, TLI, DT,
2525 case Instruction::Shl:
2526 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2527 TD, TLI, DT, MaxRecurse);
2528 case Instruction::LShr:
2529 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, TD, TLI, DT,
2531 case Instruction::AShr:
2532 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, TD, TLI, DT,
2534 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, TLI, DT,
2536 case Instruction::Or: return SimplifyOrInst (LHS, RHS, TD, TLI, DT,
2538 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, TLI, DT,
2541 if (Constant *CLHS = dyn_cast<Constant>(LHS))
2542 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
2543 Constant *COps[] = {CLHS, CRHS};
2544 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, TD, TLI);
2547 // If the operation is associative, try some generic simplifications.
2548 if (Instruction::isAssociative(Opcode))
2549 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, TLI, DT,
2553 // If the operation is with the result of a select instruction, check whether
2554 // operating on either branch of the select always yields the same value.
2555 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2556 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, TLI, DT,
2560 // If the operation is with the result of a phi instruction, check whether
2561 // operating on all incoming values of the phi always yields the same value.
2562 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2563 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, TLI, DT,
2571 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2572 const TargetData *TD, const TargetLibraryInfo *TLI,
2573 const DominatorTree *DT) {
2574 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, TLI, DT, RecursionLimit);
2577 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
2578 /// fold the result.
2579 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2580 const TargetData *TD,
2581 const TargetLibraryInfo *TLI,
2582 const DominatorTree *DT,
2583 unsigned MaxRecurse) {
2584 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
2585 return SimplifyICmpInst(Predicate, LHS, RHS, TD, TLI, DT, MaxRecurse);
2586 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, TLI, DT, MaxRecurse);
2589 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2590 const TargetData *TD, const TargetLibraryInfo *TLI,
2591 const DominatorTree *DT) {
2592 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, TLI, DT, RecursionLimit);
2595 static Value *SimplifyCallInst(CallInst *CI) {
2596 // call undef -> undef
2597 if (isa<UndefValue>(CI->getCalledValue()))
2598 return UndefValue::get(CI->getType());
2603 /// SimplifyInstruction - See if we can compute a simplified version of this
2604 /// instruction. If not, this returns null.
2605 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
2606 const TargetLibraryInfo *TLI,
2607 const DominatorTree *DT) {
2610 switch (I->getOpcode()) {
2612 Result = ConstantFoldInstruction(I, TD, TLI);
2614 case Instruction::Add:
2615 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
2616 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2617 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2620 case Instruction::Sub:
2621 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
2622 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2623 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2626 case Instruction::Mul:
2627 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2629 case Instruction::SDiv:
2630 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2632 case Instruction::UDiv:
2633 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2635 case Instruction::FDiv:
2636 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2638 case Instruction::SRem:
2639 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2641 case Instruction::URem:
2642 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2644 case Instruction::FRem:
2645 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2647 case Instruction::Shl:
2648 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
2649 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2650 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2653 case Instruction::LShr:
2654 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
2655 cast<BinaryOperator>(I)->isExact(),
2658 case Instruction::AShr:
2659 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
2660 cast<BinaryOperator>(I)->isExact(),
2663 case Instruction::And:
2664 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2666 case Instruction::Or:
2667 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2669 case Instruction::Xor:
2670 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2672 case Instruction::ICmp:
2673 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
2674 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2676 case Instruction::FCmp:
2677 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
2678 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2680 case Instruction::Select:
2681 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
2682 I->getOperand(2), TD, DT);
2684 case Instruction::GetElementPtr: {
2685 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
2686 Result = SimplifyGEPInst(Ops, TD, DT);
2689 case Instruction::InsertValue: {
2690 InsertValueInst *IV = cast<InsertValueInst>(I);
2691 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
2692 IV->getInsertedValueOperand(),
2693 IV->getIndices(), TD, DT);
2696 case Instruction::PHI:
2697 Result = SimplifyPHINode(cast<PHINode>(I), DT);
2699 case Instruction::Call:
2700 Result = SimplifyCallInst(cast<CallInst>(I));
2704 /// If called on unreachable code, the above logic may report that the
2705 /// instruction simplified to itself. Make life easier for users by
2706 /// detecting that case here, returning a safe value instead.
2707 return Result == I ? UndefValue::get(I->getType()) : Result;
2710 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
2711 /// delete the From instruction. In addition to a basic RAUW, this does a
2712 /// recursive simplification of the newly formed instructions. This catches
2713 /// things where one simplification exposes other opportunities. This only
2714 /// simplifies and deletes scalar operations, it does not change the CFG.
2716 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
2717 const TargetData *TD,
2718 const TargetLibraryInfo *TLI,
2719 const DominatorTree *DT) {
2720 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
2722 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
2723 // we can know if it gets deleted out from under us or replaced in a
2724 // recursive simplification.
2725 WeakVH FromHandle(From);
2726 WeakVH ToHandle(To);
2728 while (!From->use_empty()) {
2729 // Update the instruction to use the new value.
2730 Use &TheUse = From->use_begin().getUse();
2731 Instruction *User = cast<Instruction>(TheUse.getUser());
2734 // Check to see if the instruction can be folded due to the operand
2735 // replacement. For example changing (or X, Y) into (or X, -1) can replace
2736 // the 'or' with -1.
2737 Value *SimplifiedVal;
2739 // Sanity check to make sure 'User' doesn't dangle across
2740 // SimplifyInstruction.
2741 AssertingVH<> UserHandle(User);
2743 SimplifiedVal = SimplifyInstruction(User, TD, TLI, DT);
2744 if (SimplifiedVal == 0) continue;
2747 // Recursively simplify this user to the new value.
2748 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, TLI, DT);
2749 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
2752 assert(ToHandle && "To value deleted by recursive simplification?");
2754 // If the recursive simplification ended up revisiting and deleting
2755 // 'From' then we're done.
2760 // If 'From' has value handles referring to it, do a real RAUW to update them.
2761 From->replaceAllUsesWith(To);
2763 From->eraseFromParent();