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/ADT/Statistic.h"
22 #include "llvm/Analysis/InstructionSimplify.h"
23 #include "llvm/Analysis/ConstantFolding.h"
24 #include "llvm/Analysis/Dominators.h"
25 #include "llvm/Support/PatternMatch.h"
26 #include "llvm/Support/ValueHandle.h"
27 #include "llvm/Target/TargetData.h"
29 using namespace llvm::PatternMatch;
31 #define RecursionLimit 3
33 STATISTIC(NumExpand, "Number of expansions");
34 STATISTIC(NumFactor , "Number of factorizations");
35 STATISTIC(NumReassoc, "Number of reassociations");
37 static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
38 const DominatorTree *, unsigned);
39 static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
40 const DominatorTree *, unsigned);
41 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
42 const DominatorTree *, unsigned);
43 static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
44 const DominatorTree *, unsigned);
45 static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
46 const DominatorTree *, unsigned);
48 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
49 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
50 Instruction *I = dyn_cast<Instruction>(V);
52 // Arguments and constants dominate all instructions.
55 // If we have a DominatorTree then do a precise test.
57 return DT->dominates(I, P);
59 // Otherwise, if the instruction is in the entry block, and is not an invoke,
60 // then it obviously dominates all phi nodes.
61 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
68 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
69 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
70 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
71 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
72 /// Returns the simplified value, or null if no simplification was performed.
73 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
74 unsigned OpcodeToExpand, const TargetData *TD,
75 const DominatorTree *DT, unsigned MaxRecurse) {
76 // Recursion is always used, so bail out at once if we already hit the limit.
80 // Check whether the expression has the form "(A op' B) op C".
81 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
82 if (Op0->getOpcode() == OpcodeToExpand) {
83 // It does! Try turning it into "(A op C) op' (B op C)".
84 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
85 // Do "A op C" and "B op C" both simplify?
86 if (Value *L = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse))
87 if (Value *R = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
88 // They do! Return "L op' R" if it simplifies or is already available.
89 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
90 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
91 && L == B && R == A)) {
95 // Otherwise return "L op' R" if it simplifies.
96 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
104 // Check whether the expression has the form "A op (B op' C)".
105 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
106 if (Op1->getOpcode() == OpcodeToExpand) {
107 // It does! Try turning it into "(A op B) op' (A op C)".
108 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
109 // Do "A op B" and "A op C" both simplify?
110 if (Value *L = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse))
111 if (Value *R = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse)) {
112 // They do! Return "L op' R" if it simplifies or is already available.
113 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
114 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
115 && L == C && R == B)) {
119 // Otherwise return "L op' R" if it simplifies.
120 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
131 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
132 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
133 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
134 /// Returns the simplified value, or null if no simplification was performed.
135 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
136 unsigned OpcodeToExtract, const TargetData *TD,
137 const DominatorTree *DT, unsigned MaxRecurse) {
138 // Recursion is always used, so bail out at once if we already hit the limit.
142 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
143 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
145 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
146 !Op1 || Op1->getOpcode() != OpcodeToExtract)
149 // The expression has the form "(A op' B) op (C op' D)".
150 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
151 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
153 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
154 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
155 // commutative case, "(A op' B) op (C op' A)"?
156 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
157 Value *DD = A == C ? D : C;
158 // Form "A op' (B op DD)" if it simplifies completely.
159 // Does "B op DD" simplify?
160 if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, DT, MaxRecurse)) {
161 // It does! Return "A op' V" if it simplifies or is already available.
162 // If V equals B then "A op' V" is just the LHS.
167 // Otherwise return "A op' V" if it simplifies.
168 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, DT, MaxRecurse)) {
175 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
176 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
177 // commutative case, "(A op' B) op (B op' D)"?
178 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
179 Value *CC = B == D ? C : D;
180 // Form "(A op CC) op' B" if it simplifies completely..
181 // Does "A op CC" simplify?
182 if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, DT, MaxRecurse)) {
183 // It does! Return "V op' B" if it simplifies or is already available.
184 // If V equals A then "V op' B" is just the LHS.
189 // Otherwise return "V op' B" if it simplifies.
190 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, DT, MaxRecurse)) {
200 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
201 /// operations. Returns the simpler value, or null if none was found.
202 static Value *SimplifyAssociativeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
203 const TargetData *TD,
204 const DominatorTree *DT,
205 unsigned MaxRecurse) {
206 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
208 // Recursion is always used, so bail out at once if we already hit the limit.
212 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
213 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
215 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
216 if (Op0 && Op0->getOpcode() == Opcode) {
217 Value *A = Op0->getOperand(0);
218 Value *B = Op0->getOperand(1);
221 // Does "B op C" simplify?
222 if (Value *V = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
223 // It does! Return "A op V" if it simplifies or is already available.
224 // If V equals B then "A op V" is just the LHS.
225 if (V == B) return LHS;
226 // Otherwise return "A op V" if it simplifies.
227 if (Value *W = SimplifyBinOp(Opcode, A, V, TD, DT, MaxRecurse)) {
234 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
235 if (Op1 && Op1->getOpcode() == Opcode) {
237 Value *B = Op1->getOperand(0);
238 Value *C = Op1->getOperand(1);
240 // Does "A op B" simplify?
241 if (Value *V = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse)) {
242 // It does! Return "V op C" if it simplifies or is already available.
243 // If V equals B then "V op C" is just the RHS.
244 if (V == B) return RHS;
245 // Otherwise return "V op C" if it simplifies.
246 if (Value *W = SimplifyBinOp(Opcode, V, C, TD, DT, MaxRecurse)) {
253 // The remaining transforms require commutativity as well as associativity.
254 if (!Instruction::isCommutative(Opcode))
257 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
258 if (Op0 && Op0->getOpcode() == Opcode) {
259 Value *A = Op0->getOperand(0);
260 Value *B = Op0->getOperand(1);
263 // Does "C op A" simplify?
264 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
265 // It does! Return "V op B" if it simplifies or is already available.
266 // If V equals A then "V op B" is just the LHS.
267 if (V == A) return LHS;
268 // Otherwise return "V op B" if it simplifies.
269 if (Value *W = SimplifyBinOp(Opcode, V, B, TD, DT, MaxRecurse)) {
276 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
277 if (Op1 && Op1->getOpcode() == Opcode) {
279 Value *B = Op1->getOperand(0);
280 Value *C = Op1->getOperand(1);
282 // Does "C op A" simplify?
283 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
284 // It does! Return "B op V" if it simplifies or is already available.
285 // If V equals C then "B op V" is just the RHS.
286 if (V == C) return RHS;
287 // Otherwise return "B op V" if it simplifies.
288 if (Value *W = SimplifyBinOp(Opcode, B, V, TD, DT, MaxRecurse)) {
298 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
299 /// instruction as an operand, try to simplify the binop by seeing whether
300 /// evaluating it on both branches of the select results in the same value.
301 /// Returns the common value if so, otherwise returns null.
302 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
303 const TargetData *TD,
304 const DominatorTree *DT,
305 unsigned MaxRecurse) {
306 // Recursion is always used, so bail out at once if we already hit the limit.
311 if (isa<SelectInst>(LHS)) {
312 SI = cast<SelectInst>(LHS);
314 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
315 SI = cast<SelectInst>(RHS);
318 // Evaluate the BinOp on the true and false branches of the select.
322 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, DT, MaxRecurse);
323 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, DT, MaxRecurse);
325 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, DT, MaxRecurse);
326 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, DT, MaxRecurse);
329 // If they simplified to the same value, then return the common value.
330 // If they both failed to simplify then return null.
334 // If one branch simplified to undef, return the other one.
335 if (TV && isa<UndefValue>(TV))
337 if (FV && isa<UndefValue>(FV))
340 // If applying the operation did not change the true and false select values,
341 // then the result of the binop is the select itself.
342 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
345 // If one branch simplified and the other did not, and the simplified
346 // value is equal to the unsimplified one, return the simplified value.
347 // For example, select (cond, X, X & Z) & Z -> X & Z.
348 if ((FV && !TV) || (TV && !FV)) {
349 // Check that the simplified value has the form "X op Y" where "op" is the
350 // same as the original operation.
351 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
352 if (Simplified && Simplified->getOpcode() == Opcode) {
353 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
354 // We already know that "op" is the same as for the simplified value. See
355 // if the operands match too. If so, return the simplified value.
356 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
357 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
358 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
359 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
360 Simplified->getOperand(1) == UnsimplifiedRHS)
362 if (Simplified->isCommutative() &&
363 Simplified->getOperand(1) == UnsimplifiedLHS &&
364 Simplified->getOperand(0) == UnsimplifiedRHS)
372 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
373 /// try to simplify the comparison by seeing whether both branches of the select
374 /// result in the same value. Returns the common value if so, otherwise returns
376 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
377 Value *RHS, const TargetData *TD,
378 const DominatorTree *DT,
379 unsigned MaxRecurse) {
380 // Recursion is always used, so bail out at once if we already hit the limit.
384 // Make sure the select is on the LHS.
385 if (!isa<SelectInst>(LHS)) {
387 Pred = CmpInst::getSwappedPredicate(Pred);
389 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
390 SelectInst *SI = cast<SelectInst>(LHS);
392 // Now that we have "cmp select(cond, TV, FV), RHS", analyse it.
393 // Does "cmp TV, RHS" simplify?
394 if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT,
396 // It does! Does "cmp FV, RHS" simplify?
397 if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT,
399 // It does! If they simplified to the same value, then use it as the
400 // result of the original comparison.
406 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
407 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
408 /// it on the incoming phi values yields the same result for every value. If so
409 /// returns the common value, otherwise returns null.
410 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
411 const TargetData *TD, const DominatorTree *DT,
412 unsigned MaxRecurse) {
413 // Recursion is always used, so bail out at once if we already hit the limit.
418 if (isa<PHINode>(LHS)) {
419 PI = cast<PHINode>(LHS);
420 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
421 if (!ValueDominatesPHI(RHS, PI, DT))
424 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
425 PI = cast<PHINode>(RHS);
426 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
427 if (!ValueDominatesPHI(LHS, PI, DT))
431 // Evaluate the BinOp on the incoming phi values.
432 Value *CommonValue = 0;
433 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
434 Value *Incoming = PI->getIncomingValue(i);
435 // If the incoming value is the phi node itself, it can safely be skipped.
436 if (Incoming == PI) continue;
437 Value *V = PI == LHS ?
438 SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) :
439 SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, MaxRecurse);
440 // If the operation failed to simplify, or simplified to a different value
441 // to previously, then give up.
442 if (!V || (CommonValue && V != CommonValue))
450 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
451 /// try to simplify the comparison by seeing whether comparing with all of the
452 /// incoming phi values yields the same result every time. If so returns the
453 /// common result, otherwise returns null.
454 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
455 const TargetData *TD, const DominatorTree *DT,
456 unsigned MaxRecurse) {
457 // Recursion is always used, so bail out at once if we already hit the limit.
461 // Make sure the phi is on the LHS.
462 if (!isa<PHINode>(LHS)) {
464 Pred = CmpInst::getSwappedPredicate(Pred);
466 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
467 PHINode *PI = cast<PHINode>(LHS);
469 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
470 if (!ValueDominatesPHI(RHS, PI, DT))
473 // Evaluate the BinOp on the incoming phi values.
474 Value *CommonValue = 0;
475 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
476 Value *Incoming = PI->getIncomingValue(i);
477 // If the incoming value is the phi node itself, it can safely be skipped.
478 if (Incoming == PI) continue;
479 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse);
480 // If the operation failed to simplify, or simplified to a different value
481 // to previously, then give up.
482 if (!V || (CommonValue && V != CommonValue))
490 /// SimplifyAddInst - Given operands for an Add, see if we can
491 /// fold the result. If not, this returns null.
492 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
493 const TargetData *TD, const DominatorTree *DT,
494 unsigned MaxRecurse) {
495 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
496 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
497 Constant *Ops[] = { CLHS, CRHS };
498 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
502 // Canonicalize the constant to the RHS.
506 // X + undef -> undef
507 if (isa<UndefValue>(Op1))
511 if (match(Op1, m_Zero()))
518 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
519 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
522 // X + ~X -> -1 since ~X = -X-1
523 if (match(Op0, m_Not(m_Specific(Op1))) ||
524 match(Op1, m_Not(m_Specific(Op0))))
525 return Constant::getAllOnesValue(Op0->getType());
528 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
529 if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
532 // Try some generic simplifications for associative operations.
533 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT,
537 // Mul distributes over Add. Try some generic simplifications based on this.
538 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
542 // Threading Add over selects and phi nodes is pointless, so don't bother.
543 // Threading over the select in "A + select(cond, B, C)" means evaluating
544 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
545 // only if B and C are equal. If B and C are equal then (since we assume
546 // that operands have already been simplified) "select(cond, B, C)" should
547 // have been simplified to the common value of B and C already. Analysing
548 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
549 // for threading over phi nodes.
554 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
555 const TargetData *TD, const DominatorTree *DT) {
556 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
559 /// SimplifySubInst - Given operands for a Sub, see if we can
560 /// fold the result. If not, this returns null.
561 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
562 const TargetData *TD, const DominatorTree *DT,
563 unsigned MaxRecurse) {
564 if (Constant *CLHS = dyn_cast<Constant>(Op0))
565 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
566 Constant *Ops[] = { CLHS, CRHS };
567 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
571 // X - undef -> undef
572 // undef - X -> undef
573 if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1))
574 return UndefValue::get(Op0->getType());
577 if (match(Op1, m_Zero()))
582 return Constant::getNullValue(Op0->getType());
587 if (match(Op0, m_Add(m_Value(X), m_Specific(Op1))) ||
588 match(Op0, m_Add(m_Specific(Op1), m_Value(X))))
592 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
593 if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
596 // Mul distributes over Sub. Try some generic simplifications based on this.
597 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
601 // Threading Sub over selects and phi nodes is pointless, so don't bother.
602 // Threading over the select in "A - select(cond, B, C)" means evaluating
603 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
604 // only if B and C are equal. If B and C are equal then (since we assume
605 // that operands have already been simplified) "select(cond, B, C)" should
606 // have been simplified to the common value of B and C already. Analysing
607 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
608 // for threading over phi nodes.
613 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
614 const TargetData *TD, const DominatorTree *DT) {
615 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
618 /// SimplifyMulInst - Given operands for a Mul, see if we can
619 /// fold the result. If not, this returns null.
620 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
621 const DominatorTree *DT, unsigned MaxRecurse) {
622 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
623 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
624 Constant *Ops[] = { CLHS, CRHS };
625 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
629 // Canonicalize the constant to the RHS.
634 if (isa<UndefValue>(Op1))
635 return Constant::getNullValue(Op0->getType());
638 if (match(Op1, m_Zero()))
642 if (match(Op1, m_One()))
646 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
647 if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1))
650 // Try some generic simplifications for associative operations.
651 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
655 // Mul distributes over Add. Try some generic simplifications based on this.
656 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
660 // If the operation is with the result of a select instruction, check whether
661 // operating on either branch of the select always yields the same value.
662 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
663 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
667 // If the operation is with the result of a phi instruction, check whether
668 // operating on all incoming values of the phi always yields the same value.
669 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
670 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
677 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
678 const DominatorTree *DT) {
679 return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
682 /// SimplifyAndInst - Given operands for an And, see if we can
683 /// fold the result. If not, this returns null.
684 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
685 const DominatorTree *DT, unsigned MaxRecurse) {
686 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
687 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
688 Constant *Ops[] = { CLHS, CRHS };
689 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
693 // Canonicalize the constant to the RHS.
698 if (isa<UndefValue>(Op1))
699 return Constant::getNullValue(Op0->getType());
706 if (match(Op1, m_Zero()))
710 if (match(Op1, m_AllOnes()))
713 // A & ~A = ~A & A = 0
714 Value *A = 0, *B = 0;
715 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
716 (match(Op1, m_Not(m_Value(A))) && A == Op0))
717 return Constant::getNullValue(Op0->getType());
720 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
721 (A == Op1 || B == Op1))
725 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
726 (A == Op0 || B == Op0))
729 // Try some generic simplifications for associative operations.
730 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT,
734 // And distributes over Or. Try some generic simplifications based on this.
735 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
739 // And distributes over Xor. Try some generic simplifications based on this.
740 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
744 // Or distributes over And. Try some generic simplifications based on this.
745 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
749 // If the operation is with the result of a select instruction, check whether
750 // operating on either branch of the select always yields the same value.
751 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
752 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
756 // If the operation is with the result of a phi instruction, check whether
757 // operating on all incoming values of the phi always yields the same value.
758 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
759 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
766 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
767 const DominatorTree *DT) {
768 return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit);
771 /// SimplifyOrInst - Given operands for an Or, see if we can
772 /// fold the result. If not, this returns null.
773 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
774 const DominatorTree *DT, unsigned MaxRecurse) {
775 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
776 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
777 Constant *Ops[] = { CLHS, CRHS };
778 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
782 // Canonicalize the constant to the RHS.
787 if (isa<UndefValue>(Op1))
788 return Constant::getAllOnesValue(Op0->getType());
795 if (match(Op1, m_Zero()))
799 if (match(Op1, m_AllOnes()))
802 // A | ~A = ~A | A = -1
803 Value *A = 0, *B = 0;
804 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
805 (match(Op1, m_Not(m_Value(A))) && A == Op0))
806 return Constant::getAllOnesValue(Op0->getType());
809 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
810 (A == Op1 || B == Op1))
814 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
815 (A == Op0 || B == Op0))
818 // Try some generic simplifications for associative operations.
819 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT,
823 // Or distributes over And. Try some generic simplifications based on this.
824 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And,
828 // And distributes over Or. Try some generic simplifications based on this.
829 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
833 // If the operation is with the result of a select instruction, check whether
834 // operating on either branch of the select always yields the same value.
835 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
836 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
840 // If the operation is with the result of a phi instruction, check whether
841 // operating on all incoming values of the phi always yields the same value.
842 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
843 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
850 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
851 const DominatorTree *DT) {
852 return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
855 /// SimplifyXorInst - Given operands for a Xor, see if we can
856 /// fold the result. If not, this returns null.
857 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
858 const DominatorTree *DT, unsigned MaxRecurse) {
859 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
860 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
861 Constant *Ops[] = { CLHS, CRHS };
862 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
866 // Canonicalize the constant to the RHS.
870 // A ^ undef -> undef
871 if (isa<UndefValue>(Op1))
875 if (match(Op1, m_Zero()))
880 return Constant::getNullValue(Op0->getType());
882 // A ^ ~A = ~A ^ A = -1
884 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
885 (match(Op1, m_Not(m_Value(A))) && A == Op0))
886 return Constant::getAllOnesValue(Op0->getType());
888 // Try some generic simplifications for associative operations.
889 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT,
893 // And distributes over Xor. Try some generic simplifications based on this.
894 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
898 // Threading Xor over selects and phi nodes is pointless, so don't bother.
899 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
900 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
901 // only if B and C are equal. If B and C are equal then (since we assume
902 // that operands have already been simplified) "select(cond, B, C)" should
903 // have been simplified to the common value of B and C already. Analysing
904 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
905 // for threading over phi nodes.
910 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
911 const DominatorTree *DT) {
912 return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
915 static const Type *GetCompareTy(Value *Op) {
916 return CmpInst::makeCmpResultType(Op->getType());
919 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
920 /// fold the result. If not, this returns null.
921 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
922 const TargetData *TD, const DominatorTree *DT,
923 unsigned MaxRecurse) {
924 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
925 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
927 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
928 if (Constant *CRHS = dyn_cast<Constant>(RHS))
929 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
931 // If we have a constant, make sure it is on the RHS.
933 Pred = CmpInst::getSwappedPredicate(Pred);
936 // ITy - This is the return type of the compare we're considering.
937 const Type *ITy = GetCompareTy(LHS);
939 // icmp X, X -> true/false
940 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
941 // because X could be 0.
942 if (LHS == RHS || isa<UndefValue>(RHS))
943 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
945 // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
946 // addresses never equal each other! We already know that Op0 != Op1.
947 if ((isa<GlobalValue>(LHS) || isa<AllocaInst>(LHS) ||
948 isa<ConstantPointerNull>(LHS)) &&
949 (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
950 isa<ConstantPointerNull>(RHS)))
951 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
953 // See if we are doing a comparison with a constant.
954 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
955 // If we have an icmp le or icmp ge instruction, turn it into the
956 // appropriate icmp lt or icmp gt instruction. This allows us to rely on
957 // them being folded in the code below.
960 case ICmpInst::ICMP_ULE:
961 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
962 return ConstantInt::getTrue(CI->getContext());
964 case ICmpInst::ICMP_SLE:
965 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
966 return ConstantInt::getTrue(CI->getContext());
968 case ICmpInst::ICMP_UGE:
969 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
970 return ConstantInt::getTrue(CI->getContext());
972 case ICmpInst::ICMP_SGE:
973 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
974 return ConstantInt::getTrue(CI->getContext());
979 // If the comparison is with the result of a select instruction, check whether
980 // comparing with either branch of the select always yields the same value.
981 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
982 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
985 // If the comparison is with the result of a phi instruction, check whether
986 // doing the compare with each incoming phi value yields a common result.
987 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
988 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
994 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
995 const TargetData *TD, const DominatorTree *DT) {
996 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
999 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
1000 /// fold the result. If not, this returns null.
1001 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1002 const TargetData *TD, const DominatorTree *DT,
1003 unsigned MaxRecurse) {
1004 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1005 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
1007 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1008 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1009 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
1011 // If we have a constant, make sure it is on the RHS.
1012 std::swap(LHS, RHS);
1013 Pred = CmpInst::getSwappedPredicate(Pred);
1016 // Fold trivial predicates.
1017 if (Pred == FCmpInst::FCMP_FALSE)
1018 return ConstantInt::get(GetCompareTy(LHS), 0);
1019 if (Pred == FCmpInst::FCMP_TRUE)
1020 return ConstantInt::get(GetCompareTy(LHS), 1);
1022 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
1023 return UndefValue::get(GetCompareTy(LHS));
1025 // fcmp x,x -> true/false. Not all compares are foldable.
1027 if (CmpInst::isTrueWhenEqual(Pred))
1028 return ConstantInt::get(GetCompareTy(LHS), 1);
1029 if (CmpInst::isFalseWhenEqual(Pred))
1030 return ConstantInt::get(GetCompareTy(LHS), 0);
1033 // Handle fcmp with constant RHS
1034 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1035 // If the constant is a nan, see if we can fold the comparison based on it.
1036 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1037 if (CFP->getValueAPF().isNaN()) {
1038 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
1039 return ConstantInt::getFalse(CFP->getContext());
1040 assert(FCmpInst::isUnordered(Pred) &&
1041 "Comparison must be either ordered or unordered!");
1042 // True if unordered.
1043 return ConstantInt::getTrue(CFP->getContext());
1045 // Check whether the constant is an infinity.
1046 if (CFP->getValueAPF().isInfinity()) {
1047 if (CFP->getValueAPF().isNegative()) {
1049 case FCmpInst::FCMP_OLT:
1050 // No value is ordered and less than negative infinity.
1051 return ConstantInt::getFalse(CFP->getContext());
1052 case FCmpInst::FCMP_UGE:
1053 // All values are unordered with or at least negative infinity.
1054 return ConstantInt::getTrue(CFP->getContext());
1060 case FCmpInst::FCMP_OGT:
1061 // No value is ordered and greater than infinity.
1062 return ConstantInt::getFalse(CFP->getContext());
1063 case FCmpInst::FCMP_ULE:
1064 // All values are unordered with and at most infinity.
1065 return ConstantInt::getTrue(CFP->getContext());
1074 // If the comparison is with the result of a select instruction, check whether
1075 // comparing with either branch of the select always yields the same value.
1076 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1077 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1080 // If the comparison is with the result of a phi instruction, check whether
1081 // doing the compare with each incoming phi value yields a common result.
1082 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1083 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1089 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1090 const TargetData *TD, const DominatorTree *DT) {
1091 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1094 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
1095 /// the result. If not, this returns null.
1096 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
1097 const TargetData *TD, const DominatorTree *) {
1098 // select true, X, Y -> X
1099 // select false, X, Y -> Y
1100 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
1101 return CB->getZExtValue() ? TrueVal : FalseVal;
1103 // select C, X, X -> X
1104 if (TrueVal == FalseVal)
1107 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
1109 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
1111 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
1112 if (isa<Constant>(TrueVal))
1120 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
1121 /// fold the result. If not, this returns null.
1122 Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
1123 const TargetData *TD, const DominatorTree *) {
1124 // The type of the GEP pointer operand.
1125 const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
1127 // getelementptr P -> P.
1131 if (isa<UndefValue>(Ops[0])) {
1132 // Compute the (pointer) type returned by the GEP instruction.
1133 const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
1135 const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
1136 return UndefValue::get(GEPTy);
1140 // getelementptr P, 0 -> P.
1141 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
1144 // getelementptr P, N -> P if P points to a type of zero size.
1146 const Type *Ty = PtrTy->getElementType();
1147 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
1152 // Check to see if this is constant foldable.
1153 for (unsigned i = 0; i != NumOps; ++i)
1154 if (!isa<Constant>(Ops[i]))
1157 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
1158 (Constant *const*)Ops+1, NumOps-1);
1161 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
1162 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
1163 // If all of the PHI's incoming values are the same then replace the PHI node
1164 // with the common value.
1165 Value *CommonValue = 0;
1166 bool HasUndefInput = false;
1167 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1168 Value *Incoming = PN->getIncomingValue(i);
1169 // If the incoming value is the phi node itself, it can safely be skipped.
1170 if (Incoming == PN) continue;
1171 if (isa<UndefValue>(Incoming)) {
1172 // Remember that we saw an undef value, but otherwise ignore them.
1173 HasUndefInput = true;
1176 if (CommonValue && Incoming != CommonValue)
1177 return 0; // Not the same, bail out.
1178 CommonValue = Incoming;
1181 // If CommonValue is null then all of the incoming values were either undef or
1182 // equal to the phi node itself.
1184 return UndefValue::get(PN->getType());
1186 // If we have a PHI node like phi(X, undef, X), where X is defined by some
1187 // instruction, we cannot return X as the result of the PHI node unless it
1188 // dominates the PHI block.
1190 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
1196 //=== Helper functions for higher up the class hierarchy.
1198 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
1199 /// fold the result. If not, this returns null.
1200 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1201 const TargetData *TD, const DominatorTree *DT,
1202 unsigned MaxRecurse) {
1204 case Instruction::Add: return SimplifyAddInst(LHS, RHS, /* isNSW */ false,
1205 /* isNUW */ false, TD, DT,
1207 case Instruction::Sub: return SimplifySubInst(LHS, RHS, /* isNSW */ false,
1208 /* isNUW */ false, TD, DT,
1210 case Instruction::Mul: return SimplifyMulInst(LHS, RHS, TD, DT, MaxRecurse);
1211 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
1212 case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
1213 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
1215 if (Constant *CLHS = dyn_cast<Constant>(LHS))
1216 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
1217 Constant *COps[] = {CLHS, CRHS};
1218 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
1221 // If the operation is associative, try some generic simplifications.
1222 if (Instruction::isAssociative(Opcode))
1223 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT,
1227 // If the operation is with the result of a select instruction, check whether
1228 // operating on either branch of the select always yields the same value.
1229 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1230 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
1234 // If the operation is with the result of a phi instruction, check whether
1235 // operating on all incoming values of the phi always yields the same value.
1236 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1237 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse))
1244 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1245 const TargetData *TD, const DominatorTree *DT) {
1246 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit);
1249 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
1250 /// fold the result.
1251 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1252 const TargetData *TD, const DominatorTree *DT,
1253 unsigned MaxRecurse) {
1254 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
1255 return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1256 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1259 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1260 const TargetData *TD, const DominatorTree *DT) {
1261 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1264 /// SimplifyInstruction - See if we can compute a simplified version of this
1265 /// instruction. If not, this returns null.
1266 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
1267 const DominatorTree *DT) {
1270 switch (I->getOpcode()) {
1272 Result = ConstantFoldInstruction(I, TD);
1274 case Instruction::Add:
1275 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
1276 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1277 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1280 case Instruction::Sub:
1281 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
1282 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1283 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1286 case Instruction::Mul:
1287 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
1289 case Instruction::And:
1290 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
1292 case Instruction::Or:
1293 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1295 case Instruction::Xor:
1296 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
1298 case Instruction::ICmp:
1299 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
1300 I->getOperand(0), I->getOperand(1), TD, DT);
1302 case Instruction::FCmp:
1303 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
1304 I->getOperand(0), I->getOperand(1), TD, DT);
1306 case Instruction::Select:
1307 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
1308 I->getOperand(2), TD, DT);
1310 case Instruction::GetElementPtr: {
1311 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
1312 Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
1315 case Instruction::PHI:
1316 Result = SimplifyPHINode(cast<PHINode>(I), DT);
1320 /// If called on unreachable code, the above logic may report that the
1321 /// instruction simplified to itself. Make life easier for users by
1322 /// detecting that case here, returning a safe value instead.
1323 return Result == I ? UndefValue::get(I->getType()) : Result;
1326 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
1327 /// delete the From instruction. In addition to a basic RAUW, this does a
1328 /// recursive simplification of the newly formed instructions. This catches
1329 /// things where one simplification exposes other opportunities. This only
1330 /// simplifies and deletes scalar operations, it does not change the CFG.
1332 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
1333 const TargetData *TD,
1334 const DominatorTree *DT) {
1335 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
1337 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
1338 // we can know if it gets deleted out from under us or replaced in a
1339 // recursive simplification.
1340 WeakVH FromHandle(From);
1341 WeakVH ToHandle(To);
1343 while (!From->use_empty()) {
1344 // Update the instruction to use the new value.
1345 Use &TheUse = From->use_begin().getUse();
1346 Instruction *User = cast<Instruction>(TheUse.getUser());
1349 // Check to see if the instruction can be folded due to the operand
1350 // replacement. For example changing (or X, Y) into (or X, -1) can replace
1351 // the 'or' with -1.
1352 Value *SimplifiedVal;
1354 // Sanity check to make sure 'User' doesn't dangle across
1355 // SimplifyInstruction.
1356 AssertingVH<> UserHandle(User);
1358 SimplifiedVal = SimplifyInstruction(User, TD, DT);
1359 if (SimplifiedVal == 0) continue;
1362 // Recursively simplify this user to the new value.
1363 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT);
1364 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
1367 assert(ToHandle && "To value deleted by recursive simplification?");
1369 // If the recursive simplification ended up revisiting and deleting
1370 // 'From' then we're done.
1375 // If 'From' has value handles referring to it, do a real RAUW to update them.
1376 From->replaceAllUsesWith(To);
1378 From->eraseFromParent();