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 #include "llvm/Analysis/InstructionSimplify.h"
21 #include "llvm/Analysis/ConstantFolding.h"
22 #include "llvm/Analysis/Dominators.h"
23 #include "llvm/Support/PatternMatch.h"
24 #include "llvm/Support/ValueHandle.h"
25 #include "llvm/Target/TargetData.h"
27 using namespace llvm::PatternMatch;
29 #define RecursionLimit 3
31 static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
32 const DominatorTree *, unsigned);
33 static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
34 const DominatorTree *, unsigned);
35 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
36 const DominatorTree *, unsigned);
37 static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
38 const DominatorTree *, unsigned);
39 static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
40 const DominatorTree *, unsigned);
42 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
43 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
44 Instruction *I = dyn_cast<Instruction>(V);
46 // Arguments and constants dominate all instructions.
49 // If we have a DominatorTree then do a precise test.
51 return DT->dominates(I, P);
53 // Otherwise, if the instruction is in the entry block, and is not an invoke,
54 // then it obviously dominates all phi nodes.
55 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
62 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
63 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
64 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
65 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
66 /// Returns the simplified value, or null if no simplification was performed.
67 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
68 unsigned OpcodeToExpand, const TargetData *TD,
69 const DominatorTree *DT, unsigned MaxRecurse) {
70 // Recursion is always used, so bail out at once if we already hit the limit.
74 // Check whether the expression has the form "(A op' B) op C".
75 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
76 if (Op0->getOpcode() == OpcodeToExpand) {
77 // It does! Try turning it into "(A op C) op' (B op C)".
78 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
79 // Do "A op C" and "B op C" both simplify?
80 if (Value *L = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse))
81 if (Value *R = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
82 // They do! Return "L op' R" if it simplifies or is already available.
83 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
84 if ((L == A && R == B) ||
85 (Instruction::isCommutative(OpcodeToExpand) && L == B && R == A))
87 // Otherwise return "L op' R" if it simplifies.
88 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,MaxRecurse))
93 // Check whether the expression has the form "A op (B op' C)".
94 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
95 if (Op1->getOpcode() == OpcodeToExpand) {
96 // It does! Try turning it into "(A op B) op' (A op C)".
97 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
98 // Do "A op B" and "A op C" both simplify?
99 if (Value *L = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse))
100 if (Value *R = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse)) {
101 // They do! Return "L op' R" if it simplifies or is already available.
102 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
103 if ((L == B && R == C) ||
104 (Instruction::isCommutative(OpcodeToExpand) && L == C && R == B))
106 // Otherwise return "L op' R" if it simplifies.
107 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,MaxRecurse))
115 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
116 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
117 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
118 /// Returns the simplified value, or null if no simplification was performed.
119 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
120 unsigned OpcodeToExtract, const TargetData *TD,
121 const DominatorTree *DT, unsigned MaxRecurse) {
122 // Recursion is always used, so bail out at once if we already hit the limit.
126 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
127 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
129 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
130 !Op1 || Op1->getOpcode() != OpcodeToExtract)
133 // The expression has the form "(A op' B) op (C op' D)".
134 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
135 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
137 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
138 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
139 // commutative case, "(A op' B) op (C op' A)"?
140 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
141 Value *DD = A == C ? D : C;
142 // Form "A op' (B op DD)" if it simplifies completely.
143 // Does "B op DD" simplify?
144 if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, DT, MaxRecurse)) {
145 // It does! Return "A op' V" if it simplifies or is already available.
146 // If V equals B then "A op' V" is just the LHS.
147 if (V == B) return LHS;
148 // Otherwise return "A op' V" if it simplifies.
149 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, DT, MaxRecurse))
154 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
155 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
156 // commutative case, "(A op' B) op (B op' D)"?
157 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
158 Value *CC = B == D ? C : D;
159 // Form "(A op CC) op' B" if it simplifies completely..
160 // Does "A op CC" simplify?
161 if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, DT, MaxRecurse)) {
162 // It does! Return "V op' B" if it simplifies or is already available.
163 // If V equals A then "V op' B" is just the LHS.
164 if (V == B) return LHS;
165 // Otherwise return "V op' B" if it simplifies.
166 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, DT, MaxRecurse))
174 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
175 /// operations. Returns the simpler value, or null if none was found.
176 static Value *SimplifyAssociativeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
177 const TargetData *TD,
178 const DominatorTree *DT,
179 unsigned MaxRecurse) {
180 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
182 // Recursion is always used, so bail out at once if we already hit the limit.
186 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
187 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
189 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
190 if (Op0 && Op0->getOpcode() == Opcode) {
191 Value *A = Op0->getOperand(0);
192 Value *B = Op0->getOperand(1);
195 // Does "B op C" simplify?
196 if (Value *V = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
197 // It does! Return "A op V" if it simplifies or is already available.
198 // If V equals B then "A op V" is just the LHS.
199 if (V == B) return LHS;
200 // Otherwise return "A op V" if it simplifies.
201 if (Value *W = SimplifyBinOp(Opcode, A, V, TD, DT, MaxRecurse))
206 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
207 if (Op1 && Op1->getOpcode() == Opcode) {
209 Value *B = Op1->getOperand(0);
210 Value *C = Op1->getOperand(1);
212 // Does "A op B" simplify?
213 if (Value *V = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse)) {
214 // It does! Return "V op C" if it simplifies or is already available.
215 // If V equals B then "V op C" is just the RHS.
216 if (V == B) return RHS;
217 // Otherwise return "V op C" if it simplifies.
218 if (Value *W = SimplifyBinOp(Opcode, V, C, TD, DT, MaxRecurse))
223 // The remaining transforms require commutativity as well as associativity.
224 if (!Instruction::isCommutative(Opcode))
227 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
228 if (Op0 && Op0->getOpcode() == Opcode) {
229 Value *A = Op0->getOperand(0);
230 Value *B = Op0->getOperand(1);
233 // Does "C op A" simplify?
234 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
235 // It does! Return "V op B" if it simplifies or is already available.
236 // If V equals A then "V op B" is just the LHS.
237 if (V == A) return LHS;
238 // Otherwise return "V op B" if it simplifies.
239 if (Value *W = SimplifyBinOp(Opcode, V, B, TD, DT, MaxRecurse))
244 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
245 if (Op1 && Op1->getOpcode() == Opcode) {
247 Value *B = Op1->getOperand(0);
248 Value *C = Op1->getOperand(1);
250 // Does "C op A" simplify?
251 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
252 // It does! Return "B op V" if it simplifies or is already available.
253 // If V equals C then "B op V" is just the RHS.
254 if (V == C) return RHS;
255 // Otherwise return "B op V" if it simplifies.
256 if (Value *W = SimplifyBinOp(Opcode, B, V, TD, DT, MaxRecurse))
264 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
265 /// instruction as an operand, try to simplify the binop by seeing whether
266 /// evaluating it on both branches of the select results in the same value.
267 /// Returns the common value if so, otherwise returns null.
268 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
269 const TargetData *TD,
270 const DominatorTree *DT,
271 unsigned MaxRecurse) {
272 // Recursion is always used, so bail out at once if we already hit the limit.
277 if (isa<SelectInst>(LHS)) {
278 SI = cast<SelectInst>(LHS);
280 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
281 SI = cast<SelectInst>(RHS);
284 // Evaluate the BinOp on the true and false branches of the select.
288 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, DT, MaxRecurse);
289 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, DT, MaxRecurse);
291 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, DT, MaxRecurse);
292 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, DT, MaxRecurse);
295 // If they simplified to the same value, then return the common value.
296 // If they both failed to simplify then return null.
300 // If one branch simplified to undef, return the other one.
301 if (TV && isa<UndefValue>(TV))
303 if (FV && isa<UndefValue>(FV))
306 // If applying the operation did not change the true and false select values,
307 // then the result of the binop is the select itself.
308 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
311 // If one branch simplified and the other did not, and the simplified
312 // value is equal to the unsimplified one, return the simplified value.
313 // For example, select (cond, X, X & Z) & Z -> X & Z.
314 if ((FV && !TV) || (TV && !FV)) {
315 // Check that the simplified value has the form "X op Y" where "op" is the
316 // same as the original operation.
317 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
318 if (Simplified && Simplified->getOpcode() == Opcode) {
319 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
320 // We already know that "op" is the same as for the simplified value. See
321 // if the operands match too. If so, return the simplified value.
322 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
323 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
324 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
325 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
326 Simplified->getOperand(1) == UnsimplifiedRHS)
328 if (Simplified->isCommutative() &&
329 Simplified->getOperand(1) == UnsimplifiedLHS &&
330 Simplified->getOperand(0) == UnsimplifiedRHS)
338 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
339 /// try to simplify the comparison by seeing whether both branches of the select
340 /// result in the same value. Returns the common value if so, otherwise returns
342 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
343 Value *RHS, const TargetData *TD,
344 const DominatorTree *DT,
345 unsigned MaxRecurse) {
346 // Recursion is always used, so bail out at once if we already hit the limit.
350 // Make sure the select is on the LHS.
351 if (!isa<SelectInst>(LHS)) {
353 Pred = CmpInst::getSwappedPredicate(Pred);
355 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
356 SelectInst *SI = cast<SelectInst>(LHS);
358 // Now that we have "cmp select(cond, TV, FV), RHS", analyse it.
359 // Does "cmp TV, RHS" simplify?
360 if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT,
362 // It does! Does "cmp FV, RHS" simplify?
363 if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT,
365 // It does! If they simplified to the same value, then use it as the
366 // result of the original comparison.
372 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
373 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
374 /// it on the incoming phi values yields the same result for every value. If so
375 /// returns the common value, otherwise returns null.
376 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
377 const TargetData *TD, const DominatorTree *DT,
378 unsigned MaxRecurse) {
379 // Recursion is always used, so bail out at once if we already hit the limit.
384 if (isa<PHINode>(LHS)) {
385 PI = cast<PHINode>(LHS);
386 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
387 if (!ValueDominatesPHI(RHS, PI, DT))
390 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
391 PI = cast<PHINode>(RHS);
392 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
393 if (!ValueDominatesPHI(LHS, PI, DT))
397 // Evaluate the BinOp on the incoming phi values.
398 Value *CommonValue = 0;
399 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
400 Value *Incoming = PI->getIncomingValue(i);
401 // If the incoming value is the phi node itself, it can safely be skipped.
402 if (Incoming == PI) continue;
403 Value *V = PI == LHS ?
404 SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) :
405 SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, MaxRecurse);
406 // If the operation failed to simplify, or simplified to a different value
407 // to previously, then give up.
408 if (!V || (CommonValue && V != CommonValue))
416 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
417 /// try to simplify the comparison by seeing whether comparing with all of the
418 /// incoming phi values yields the same result every time. If so returns the
419 /// common result, otherwise returns null.
420 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
421 const TargetData *TD, const DominatorTree *DT,
422 unsigned MaxRecurse) {
423 // Recursion is always used, so bail out at once if we already hit the limit.
427 // Make sure the phi is on the LHS.
428 if (!isa<PHINode>(LHS)) {
430 Pred = CmpInst::getSwappedPredicate(Pred);
432 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
433 PHINode *PI = cast<PHINode>(LHS);
435 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
436 if (!ValueDominatesPHI(RHS, PI, DT))
439 // Evaluate the BinOp on the incoming phi values.
440 Value *CommonValue = 0;
441 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
442 Value *Incoming = PI->getIncomingValue(i);
443 // If the incoming value is the phi node itself, it can safely be skipped.
444 if (Incoming == PI) continue;
445 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse);
446 // If the operation failed to simplify, or simplified to a different value
447 // to previously, then give up.
448 if (!V || (CommonValue && V != CommonValue))
456 /// SimplifyAddInst - Given operands for an Add, see if we can
457 /// fold the result. If not, this returns null.
458 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
459 const TargetData *TD, const DominatorTree *DT,
460 unsigned MaxRecurse) {
461 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
462 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
463 Constant *Ops[] = { CLHS, CRHS };
464 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
468 // Canonicalize the constant to the RHS.
472 // X + undef -> undef
473 if (isa<UndefValue>(Op1))
477 if (match(Op1, m_Zero()))
484 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
485 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
488 // X + ~X -> -1 since ~X = -X-1
489 if (match(Op0, m_Not(m_Specific(Op1))) ||
490 match(Op1, m_Not(m_Specific(Op0))))
491 return Constant::getAllOnesValue(Op0->getType());
494 if (!MaxRecurse && Op0->getType()->isIntegerTy(1))
495 return SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1);
497 // Try some generic simplifications for associative operations.
498 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT,
502 // Mul distributes over Add. Try some generic simplifications based on this.
503 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
507 // Threading Add over selects and phi nodes is pointless, so don't bother.
508 // Threading over the select in "A + select(cond, B, C)" means evaluating
509 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
510 // only if B and C are equal. If B and C are equal then (since we assume
511 // that operands have already been simplified) "select(cond, B, C)" should
512 // have been simplified to the common value of B and C already. Analysing
513 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
514 // for threading over phi nodes.
519 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
520 const TargetData *TD, const DominatorTree *DT) {
521 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
524 /// SimplifySubInst - Given operands for a Sub, see if we can
525 /// fold the result. If not, this returns null.
526 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
527 const TargetData *TD, const DominatorTree *DT,
528 unsigned MaxRecurse) {
529 if (Constant *CLHS = dyn_cast<Constant>(Op0))
530 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
531 Constant *Ops[] = { CLHS, CRHS };
532 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
536 // X - undef -> undef
537 // undef - X -> undef
538 if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1))
539 return UndefValue::get(Op0->getType());
542 if (match(Op1, m_Zero()))
547 return Constant::getNullValue(Op0->getType());
552 if (match(Op0, m_Add(m_Value(X), m_Specific(Op1))) ||
553 match(Op0, m_Add(m_Specific(Op1), m_Value(X))))
557 if (!MaxRecurse && Op0->getType()->isIntegerTy(1))
558 return SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1);
560 // Mul distributes over Sub. Try some generic simplifications based on this.
561 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
565 // Threading Sub over selects and phi nodes is pointless, so don't bother.
566 // Threading over the select in "A - select(cond, B, C)" means evaluating
567 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
568 // only if B and C are equal. If B and C are equal then (since we assume
569 // that operands have already been simplified) "select(cond, B, C)" should
570 // have been simplified to the common value of B and C already. Analysing
571 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
572 // for threading over phi nodes.
577 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
578 const TargetData *TD, const DominatorTree *DT) {
579 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
582 /// SimplifyMulInst - Given operands for a Mul, see if we can
583 /// fold the result. If not, this returns null.
584 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
585 const DominatorTree *DT, unsigned MaxRecurse) {
586 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
587 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
588 Constant *Ops[] = { CLHS, CRHS };
589 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
593 // Canonicalize the constant to the RHS.
598 if (isa<UndefValue>(Op1))
599 return Constant::getNullValue(Op0->getType());
602 if (match(Op1, m_Zero()))
606 if (match(Op1, m_One()))
610 if (!MaxRecurse && Op0->getType()->isIntegerTy(1))
611 return SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1);
613 // Try some generic simplifications for associative operations.
614 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
618 // Mul distributes over Add. Try some generic simplifications based on this.
619 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
623 // If the operation is with the result of a select instruction, check whether
624 // operating on either branch of the select always yields the same value.
625 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
626 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
630 // If the operation is with the result of a phi instruction, check whether
631 // operating on all incoming values of the phi always yields the same value.
632 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
633 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
640 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
641 const DominatorTree *DT) {
642 return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
645 /// SimplifyAndInst - Given operands for an And, see if we can
646 /// fold the result. If not, this returns null.
647 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
648 const DominatorTree *DT, unsigned MaxRecurse) {
649 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
650 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
651 Constant *Ops[] = { CLHS, CRHS };
652 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
656 // Canonicalize the constant to the RHS.
661 if (isa<UndefValue>(Op1))
662 return Constant::getNullValue(Op0->getType());
669 if (match(Op1, m_Zero()))
673 if (match(Op1, m_AllOnes()))
676 // A & ~A = ~A & A = 0
677 Value *A = 0, *B = 0;
678 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
679 (match(Op1, m_Not(m_Value(A))) && A == Op0))
680 return Constant::getNullValue(Op0->getType());
683 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
684 (A == Op1 || B == Op1))
688 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
689 (A == Op0 || B == Op0))
692 // Try some generic simplifications for associative operations.
693 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT,
697 // And distributes over Or. Try some generic simplifications based on this.
698 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
702 // And distributes over Xor. Try some generic simplifications based on this.
703 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
707 // Or distributes over And. Try some generic simplifications based on this.
708 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
712 // If the operation is with the result of a select instruction, check whether
713 // operating on either branch of the select always yields the same value.
714 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
715 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
719 // If the operation is with the result of a phi instruction, check whether
720 // operating on all incoming values of the phi always yields the same value.
721 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
722 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
729 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
730 const DominatorTree *DT) {
731 return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit);
734 /// SimplifyOrInst - Given operands for an Or, see if we can
735 /// fold the result. If not, this returns null.
736 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
737 const DominatorTree *DT, unsigned MaxRecurse) {
738 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
739 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
740 Constant *Ops[] = { CLHS, CRHS };
741 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
745 // Canonicalize the constant to the RHS.
750 if (isa<UndefValue>(Op1))
751 return Constant::getAllOnesValue(Op0->getType());
758 if (match(Op1, m_Zero()))
762 if (match(Op1, m_AllOnes()))
765 // A | ~A = ~A | A = -1
766 Value *A = 0, *B = 0;
767 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
768 (match(Op1, m_Not(m_Value(A))) && A == Op0))
769 return Constant::getAllOnesValue(Op0->getType());
772 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
773 (A == Op1 || B == Op1))
777 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
778 (A == Op0 || B == Op0))
781 // Try some generic simplifications for associative operations.
782 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT,
786 // Or distributes over And. Try some generic simplifications based on this.
787 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And,
791 // And distributes over Or. Try some generic simplifications based on this.
792 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
796 // If the operation is with the result of a select instruction, check whether
797 // operating on either branch of the select always yields the same value.
798 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
799 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
803 // If the operation is with the result of a phi instruction, check whether
804 // operating on all incoming values of the phi always yields the same value.
805 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
806 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
813 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
814 const DominatorTree *DT) {
815 return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
818 /// SimplifyXorInst - Given operands for a Xor, see if we can
819 /// fold the result. If not, this returns null.
820 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
821 const DominatorTree *DT, unsigned MaxRecurse) {
822 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
823 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
824 Constant *Ops[] = { CLHS, CRHS };
825 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
829 // Canonicalize the constant to the RHS.
833 // A ^ undef -> undef
834 if (isa<UndefValue>(Op1))
838 if (match(Op1, m_Zero()))
843 return Constant::getNullValue(Op0->getType());
845 // A ^ ~A = ~A ^ A = -1
847 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
848 (match(Op1, m_Not(m_Value(A))) && A == Op0))
849 return Constant::getAllOnesValue(Op0->getType());
851 // Try some generic simplifications for associative operations.
852 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT,
856 // And distributes over Xor. Try some generic simplifications based on this.
857 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
861 // Threading Xor over selects and phi nodes is pointless, so don't bother.
862 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
863 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
864 // only if B and C are equal. If B and C are equal then (since we assume
865 // that operands have already been simplified) "select(cond, B, C)" should
866 // have been simplified to the common value of B and C already. Analysing
867 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
868 // for threading over phi nodes.
873 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
874 const DominatorTree *DT) {
875 return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
878 static const Type *GetCompareTy(Value *Op) {
879 return CmpInst::makeCmpResultType(Op->getType());
882 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
883 /// fold the result. If not, this returns null.
884 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
885 const TargetData *TD, const DominatorTree *DT,
886 unsigned MaxRecurse) {
887 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
888 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
890 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
891 if (Constant *CRHS = dyn_cast<Constant>(RHS))
892 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
894 // If we have a constant, make sure it is on the RHS.
896 Pred = CmpInst::getSwappedPredicate(Pred);
899 // ITy - This is the return type of the compare we're considering.
900 const Type *ITy = GetCompareTy(LHS);
902 // icmp X, X -> true/false
903 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
904 // because X could be 0.
905 if (LHS == RHS || isa<UndefValue>(RHS))
906 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
908 // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
909 // addresses never equal each other! We already know that Op0 != Op1.
910 if ((isa<GlobalValue>(LHS) || isa<AllocaInst>(LHS) ||
911 isa<ConstantPointerNull>(LHS)) &&
912 (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
913 isa<ConstantPointerNull>(RHS)))
914 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
916 // See if we are doing a comparison with a constant.
917 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
918 // If we have an icmp le or icmp ge instruction, turn it into the
919 // appropriate icmp lt or icmp gt instruction. This allows us to rely on
920 // them being folded in the code below.
923 case ICmpInst::ICMP_ULE:
924 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
925 return ConstantInt::getTrue(CI->getContext());
927 case ICmpInst::ICMP_SLE:
928 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
929 return ConstantInt::getTrue(CI->getContext());
931 case ICmpInst::ICMP_UGE:
932 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
933 return ConstantInt::getTrue(CI->getContext());
935 case ICmpInst::ICMP_SGE:
936 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
937 return ConstantInt::getTrue(CI->getContext());
942 // If the comparison is with the result of a select instruction, check whether
943 // comparing with either branch of the select always yields the same value.
944 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
945 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
948 // If the comparison is with the result of a phi instruction, check whether
949 // doing the compare with each incoming phi value yields a common result.
950 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
951 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
957 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
958 const TargetData *TD, const DominatorTree *DT) {
959 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
962 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
963 /// fold the result. If not, this returns null.
964 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
965 const TargetData *TD, const DominatorTree *DT,
966 unsigned MaxRecurse) {
967 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
968 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
970 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
971 if (Constant *CRHS = dyn_cast<Constant>(RHS))
972 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
974 // If we have a constant, make sure it is on the RHS.
976 Pred = CmpInst::getSwappedPredicate(Pred);
979 // Fold trivial predicates.
980 if (Pred == FCmpInst::FCMP_FALSE)
981 return ConstantInt::get(GetCompareTy(LHS), 0);
982 if (Pred == FCmpInst::FCMP_TRUE)
983 return ConstantInt::get(GetCompareTy(LHS), 1);
985 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
986 return UndefValue::get(GetCompareTy(LHS));
988 // fcmp x,x -> true/false. Not all compares are foldable.
990 if (CmpInst::isTrueWhenEqual(Pred))
991 return ConstantInt::get(GetCompareTy(LHS), 1);
992 if (CmpInst::isFalseWhenEqual(Pred))
993 return ConstantInt::get(GetCompareTy(LHS), 0);
996 // Handle fcmp with constant RHS
997 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
998 // If the constant is a nan, see if we can fold the comparison based on it.
999 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1000 if (CFP->getValueAPF().isNaN()) {
1001 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
1002 return ConstantInt::getFalse(CFP->getContext());
1003 assert(FCmpInst::isUnordered(Pred) &&
1004 "Comparison must be either ordered or unordered!");
1005 // True if unordered.
1006 return ConstantInt::getTrue(CFP->getContext());
1008 // Check whether the constant is an infinity.
1009 if (CFP->getValueAPF().isInfinity()) {
1010 if (CFP->getValueAPF().isNegative()) {
1012 case FCmpInst::FCMP_OLT:
1013 // No value is ordered and less than negative infinity.
1014 return ConstantInt::getFalse(CFP->getContext());
1015 case FCmpInst::FCMP_UGE:
1016 // All values are unordered with or at least negative infinity.
1017 return ConstantInt::getTrue(CFP->getContext());
1023 case FCmpInst::FCMP_OGT:
1024 // No value is ordered and greater than infinity.
1025 return ConstantInt::getFalse(CFP->getContext());
1026 case FCmpInst::FCMP_ULE:
1027 // All values are unordered with and at most infinity.
1028 return ConstantInt::getTrue(CFP->getContext());
1037 // If the comparison is with the result of a select instruction, check whether
1038 // comparing with either branch of the select always yields the same value.
1039 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1040 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1043 // If the comparison is with the result of a phi instruction, check whether
1044 // doing the compare with each incoming phi value yields a common result.
1045 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1046 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1052 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1053 const TargetData *TD, const DominatorTree *DT) {
1054 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1057 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
1058 /// the result. If not, this returns null.
1059 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
1060 const TargetData *TD, const DominatorTree *) {
1061 // select true, X, Y -> X
1062 // select false, X, Y -> Y
1063 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
1064 return CB->getZExtValue() ? TrueVal : FalseVal;
1066 // select C, X, X -> X
1067 if (TrueVal == FalseVal)
1070 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
1072 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
1074 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
1075 if (isa<Constant>(TrueVal))
1083 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
1084 /// fold the result. If not, this returns null.
1085 Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
1086 const TargetData *TD, const DominatorTree *) {
1087 // The type of the GEP pointer operand.
1088 const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
1090 // getelementptr P -> P.
1094 if (isa<UndefValue>(Ops[0])) {
1095 // Compute the (pointer) type returned by the GEP instruction.
1096 const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
1098 const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
1099 return UndefValue::get(GEPTy);
1103 // getelementptr P, 0 -> P.
1104 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
1107 // getelementptr P, N -> P if P points to a type of zero size.
1109 const Type *Ty = PtrTy->getElementType();
1110 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
1115 // Check to see if this is constant foldable.
1116 for (unsigned i = 0; i != NumOps; ++i)
1117 if (!isa<Constant>(Ops[i]))
1120 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
1121 (Constant *const*)Ops+1, NumOps-1);
1124 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
1125 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
1126 // If all of the PHI's incoming values are the same then replace the PHI node
1127 // with the common value.
1128 Value *CommonValue = 0;
1129 bool HasUndefInput = false;
1130 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1131 Value *Incoming = PN->getIncomingValue(i);
1132 // If the incoming value is the phi node itself, it can safely be skipped.
1133 if (Incoming == PN) continue;
1134 if (isa<UndefValue>(Incoming)) {
1135 // Remember that we saw an undef value, but otherwise ignore them.
1136 HasUndefInput = true;
1139 if (CommonValue && Incoming != CommonValue)
1140 return 0; // Not the same, bail out.
1141 CommonValue = Incoming;
1144 // If CommonValue is null then all of the incoming values were either undef or
1145 // equal to the phi node itself.
1147 return UndefValue::get(PN->getType());
1149 // If we have a PHI node like phi(X, undef, X), where X is defined by some
1150 // instruction, we cannot return X as the result of the PHI node unless it
1151 // dominates the PHI block.
1153 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
1159 //=== Helper functions for higher up the class hierarchy.
1161 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
1162 /// fold the result. If not, this returns null.
1163 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1164 const TargetData *TD, const DominatorTree *DT,
1165 unsigned MaxRecurse) {
1167 case Instruction::Add: return SimplifyAddInst(LHS, RHS, /* isNSW */ false,
1168 /* isNUW */ false, TD, DT,
1170 case Instruction::Sub: return SimplifySubInst(LHS, RHS, /* isNSW */ false,
1171 /* isNUW */ false, TD, DT,
1173 case Instruction::Mul: return SimplifyMulInst(LHS, RHS, TD, DT, MaxRecurse);
1174 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
1175 case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
1176 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
1178 if (Constant *CLHS = dyn_cast<Constant>(LHS))
1179 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
1180 Constant *COps[] = {CLHS, CRHS};
1181 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
1184 // If the operation is associative, try some generic simplifications.
1185 if (Instruction::isAssociative(Opcode))
1186 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT,
1190 // If the operation is with the result of a select instruction, check whether
1191 // operating on either branch of the select always yields the same value.
1192 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1193 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
1197 // If the operation is with the result of a phi instruction, check whether
1198 // operating on all incoming values of the phi always yields the same value.
1199 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1200 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse))
1207 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1208 const TargetData *TD, const DominatorTree *DT) {
1209 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit);
1212 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
1213 /// fold the result.
1214 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1215 const TargetData *TD, const DominatorTree *DT,
1216 unsigned MaxRecurse) {
1217 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
1218 return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1219 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1222 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1223 const TargetData *TD, const DominatorTree *DT) {
1224 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1227 /// SimplifyInstruction - See if we can compute a simplified version of this
1228 /// instruction. If not, this returns null.
1229 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
1230 const DominatorTree *DT) {
1233 switch (I->getOpcode()) {
1235 Result = ConstantFoldInstruction(I, TD);
1237 case Instruction::Add:
1238 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
1239 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1240 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1243 case Instruction::Sub:
1244 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
1245 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1246 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1249 case Instruction::Mul:
1250 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
1252 case Instruction::And:
1253 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
1255 case Instruction::Or:
1256 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1258 case Instruction::Xor:
1259 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
1261 case Instruction::ICmp:
1262 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
1263 I->getOperand(0), I->getOperand(1), TD, DT);
1265 case Instruction::FCmp:
1266 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
1267 I->getOperand(0), I->getOperand(1), TD, DT);
1269 case Instruction::Select:
1270 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
1271 I->getOperand(2), TD, DT);
1273 case Instruction::GetElementPtr: {
1274 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
1275 Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
1278 case Instruction::PHI:
1279 Result = SimplifyPHINode(cast<PHINode>(I), DT);
1283 /// If called on unreachable code, the above logic may report that the
1284 /// instruction simplified to itself. Make life easier for users by
1285 /// detecting that case here, returning a safe value instead.
1286 return Result == I ? UndefValue::get(I->getType()) : Result;
1289 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
1290 /// delete the From instruction. In addition to a basic RAUW, this does a
1291 /// recursive simplification of the newly formed instructions. This catches
1292 /// things where one simplification exposes other opportunities. This only
1293 /// simplifies and deletes scalar operations, it does not change the CFG.
1295 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
1296 const TargetData *TD,
1297 const DominatorTree *DT) {
1298 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
1300 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
1301 // we can know if it gets deleted out from under us or replaced in a
1302 // recursive simplification.
1303 WeakVH FromHandle(From);
1304 WeakVH ToHandle(To);
1306 while (!From->use_empty()) {
1307 // Update the instruction to use the new value.
1308 Use &TheUse = From->use_begin().getUse();
1309 Instruction *User = cast<Instruction>(TheUse.getUser());
1312 // Check to see if the instruction can be folded due to the operand
1313 // replacement. For example changing (or X, Y) into (or X, -1) can replace
1314 // the 'or' with -1.
1315 Value *SimplifiedVal;
1317 // Sanity check to make sure 'User' doesn't dangle across
1318 // SimplifyInstruction.
1319 AssertingVH<> UserHandle(User);
1321 SimplifiedVal = SimplifyInstruction(User, TD, DT);
1322 if (SimplifiedVal == 0) continue;
1325 // Recursively simplify this user to the new value.
1326 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT);
1327 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
1330 assert(ToHandle && "To value deleted by recursive simplification?");
1332 // If the recursive simplification ended up revisiting and deleting
1333 // 'From' then we're done.
1338 // If 'From' has value handles referring to it, do a real RAUW to update them.
1339 From->replaceAllUsesWith(To);
1341 From->eraseFromParent();