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 OpcToExpand, const TargetData *TD,
75 const DominatorTree *DT, unsigned MaxRecurse) {
76 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
77 // Recursion is always used, so bail out at once if we already hit the limit.
81 // Check whether the expression has the form "(A op' B) op C".
82 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
83 if (Op0->getOpcode() == OpcodeToExpand) {
84 // It does! Try turning it into "(A op C) op' (B op C)".
85 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
86 // Do "A op C" and "B op C" both simplify?
87 if (Value *L = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse))
88 if (Value *R = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
89 // They do! Return "L op' R" if it simplifies or is already available.
90 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
91 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
92 && L == B && R == A)) {
96 // Otherwise return "L op' R" if it simplifies.
97 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
105 // Check whether the expression has the form "A op (B op' C)".
106 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
107 if (Op1->getOpcode() == OpcodeToExpand) {
108 // It does! Try turning it into "(A op B) op' (A op C)".
109 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
110 // Do "A op B" and "A op C" both simplify?
111 if (Value *L = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse))
112 if (Value *R = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse)) {
113 // They do! Return "L op' R" if it simplifies or is already available.
114 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
115 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
116 && L == C && R == B)) {
120 // Otherwise return "L op' R" if it simplifies.
121 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
132 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
133 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
134 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
135 /// Returns the simplified value, or null if no simplification was performed.
136 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
137 unsigned OpcToExtract, const TargetData *TD,
138 const DominatorTree *DT, unsigned MaxRecurse) {
139 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
140 // Recursion is always used, so bail out at once if we already hit the limit.
144 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
145 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
147 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
148 !Op1 || Op1->getOpcode() != OpcodeToExtract)
151 // The expression has the form "(A op' B) op (C op' D)".
152 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
153 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
155 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
156 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
157 // commutative case, "(A op' B) op (C op' A)"?
158 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
159 Value *DD = A == C ? D : C;
160 // Form "A op' (B op DD)" if it simplifies completely.
161 // Does "B op DD" simplify?
162 if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, DT, MaxRecurse)) {
163 // It does! Return "A op' V" if it simplifies or is already available.
164 // If V equals B then "A op' V" is just the LHS. If V equals DD then
165 // "A op' V" is just the RHS.
166 if (V == B || V == DD) {
168 return V == B ? LHS : RHS;
170 // Otherwise return "A op' V" if it simplifies.
171 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, DT, MaxRecurse)) {
178 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
179 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
180 // commutative case, "(A op' B) op (B op' D)"?
181 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
182 Value *CC = B == D ? C : D;
183 // Form "(A op CC) op' B" if it simplifies completely..
184 // Does "A op CC" simplify?
185 if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, DT, MaxRecurse)) {
186 // It does! Return "V op' B" if it simplifies or is already available.
187 // If V equals A then "V op' B" is just the LHS. If V equals CC then
188 // "V op' B" is just the RHS.
189 if (V == A || V == CC) {
191 return V == A ? LHS : RHS;
193 // Otherwise return "V op' B" if it simplifies.
194 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, DT, MaxRecurse)) {
204 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
205 /// operations. Returns the simpler value, or null if none was found.
206 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
207 const TargetData *TD,
208 const DominatorTree *DT,
209 unsigned MaxRecurse) {
210 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
211 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
213 // Recursion is always used, so bail out at once if we already hit the limit.
217 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
218 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
220 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
221 if (Op0 && Op0->getOpcode() == Opcode) {
222 Value *A = Op0->getOperand(0);
223 Value *B = Op0->getOperand(1);
226 // Does "B op C" simplify?
227 if (Value *V = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
228 // It does! Return "A op V" if it simplifies or is already available.
229 // If V equals B then "A op V" is just the LHS.
230 if (V == B) return LHS;
231 // Otherwise return "A op V" if it simplifies.
232 if (Value *W = SimplifyBinOp(Opcode, A, V, TD, DT, MaxRecurse)) {
239 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
240 if (Op1 && Op1->getOpcode() == Opcode) {
242 Value *B = Op1->getOperand(0);
243 Value *C = Op1->getOperand(1);
245 // Does "A op B" simplify?
246 if (Value *V = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse)) {
247 // It does! Return "V op C" if it simplifies or is already available.
248 // If V equals B then "V op C" is just the RHS.
249 if (V == B) return RHS;
250 // Otherwise return "V op C" if it simplifies.
251 if (Value *W = SimplifyBinOp(Opcode, V, C, TD, DT, MaxRecurse)) {
258 // The remaining transforms require commutativity as well as associativity.
259 if (!Instruction::isCommutative(Opcode))
262 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
263 if (Op0 && Op0->getOpcode() == Opcode) {
264 Value *A = Op0->getOperand(0);
265 Value *B = Op0->getOperand(1);
268 // Does "C op A" simplify?
269 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
270 // It does! Return "V op B" if it simplifies or is already available.
271 // If V equals A then "V op B" is just the LHS.
272 if (V == A) return LHS;
273 // Otherwise return "V op B" if it simplifies.
274 if (Value *W = SimplifyBinOp(Opcode, V, B, TD, DT, MaxRecurse)) {
281 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
282 if (Op1 && Op1->getOpcode() == Opcode) {
284 Value *B = Op1->getOperand(0);
285 Value *C = Op1->getOperand(1);
287 // Does "C op A" simplify?
288 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
289 // It does! Return "B op V" if it simplifies or is already available.
290 // If V equals C then "B op V" is just the RHS.
291 if (V == C) return RHS;
292 // Otherwise return "B op V" if it simplifies.
293 if (Value *W = SimplifyBinOp(Opcode, B, V, TD, DT, MaxRecurse)) {
303 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
304 /// instruction as an operand, try to simplify the binop by seeing whether
305 /// evaluating it on both branches of the select results in the same value.
306 /// Returns the common value if so, otherwise returns null.
307 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
308 const TargetData *TD,
309 const DominatorTree *DT,
310 unsigned MaxRecurse) {
311 // Recursion is always used, so bail out at once if we already hit the limit.
316 if (isa<SelectInst>(LHS)) {
317 SI = cast<SelectInst>(LHS);
319 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
320 SI = cast<SelectInst>(RHS);
323 // Evaluate the BinOp on the true and false branches of the select.
327 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, DT, MaxRecurse);
328 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, DT, MaxRecurse);
330 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, DT, MaxRecurse);
331 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, DT, MaxRecurse);
334 // If they simplified to the same value, then return the common value.
335 // If they both failed to simplify then return null.
339 // If one branch simplified to undef, return the other one.
340 if (TV && isa<UndefValue>(TV))
342 if (FV && isa<UndefValue>(FV))
345 // If applying the operation did not change the true and false select values,
346 // then the result of the binop is the select itself.
347 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
350 // If one branch simplified and the other did not, and the simplified
351 // value is equal to the unsimplified one, return the simplified value.
352 // For example, select (cond, X, X & Z) & Z -> X & Z.
353 if ((FV && !TV) || (TV && !FV)) {
354 // Check that the simplified value has the form "X op Y" where "op" is the
355 // same as the original operation.
356 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
357 if (Simplified && Simplified->getOpcode() == Opcode) {
358 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
359 // We already know that "op" is the same as for the simplified value. See
360 // if the operands match too. If so, return the simplified value.
361 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
362 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
363 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
364 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
365 Simplified->getOperand(1) == UnsimplifiedRHS)
367 if (Simplified->isCommutative() &&
368 Simplified->getOperand(1) == UnsimplifiedLHS &&
369 Simplified->getOperand(0) == UnsimplifiedRHS)
377 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
378 /// try to simplify the comparison by seeing whether both branches of the select
379 /// result in the same value. Returns the common value if so, otherwise returns
381 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
382 Value *RHS, const TargetData *TD,
383 const DominatorTree *DT,
384 unsigned MaxRecurse) {
385 // Recursion is always used, so bail out at once if we already hit the limit.
389 // Make sure the select is on the LHS.
390 if (!isa<SelectInst>(LHS)) {
392 Pred = CmpInst::getSwappedPredicate(Pred);
394 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
395 SelectInst *SI = cast<SelectInst>(LHS);
397 // Now that we have "cmp select(cond, TV, FV), RHS", analyse it.
398 // Does "cmp TV, RHS" simplify?
399 if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT,
401 // It does! Does "cmp FV, RHS" simplify?
402 if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT,
404 // It does! If they simplified to the same value, then use it as the
405 // result of the original comparison.
411 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
412 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
413 /// it on the incoming phi values yields the same result for every value. If so
414 /// returns the common value, otherwise returns null.
415 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
416 const TargetData *TD, const DominatorTree *DT,
417 unsigned MaxRecurse) {
418 // Recursion is always used, so bail out at once if we already hit the limit.
423 if (isa<PHINode>(LHS)) {
424 PI = cast<PHINode>(LHS);
425 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
426 if (!ValueDominatesPHI(RHS, PI, DT))
429 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
430 PI = cast<PHINode>(RHS);
431 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
432 if (!ValueDominatesPHI(LHS, PI, DT))
436 // Evaluate the BinOp on the incoming phi values.
437 Value *CommonValue = 0;
438 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
439 Value *Incoming = PI->getIncomingValue(i);
440 // If the incoming value is the phi node itself, it can safely be skipped.
441 if (Incoming == PI) continue;
442 Value *V = PI == LHS ?
443 SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) :
444 SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, MaxRecurse);
445 // If the operation failed to simplify, or simplified to a different value
446 // to previously, then give up.
447 if (!V || (CommonValue && V != CommonValue))
455 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
456 /// try to simplify the comparison by seeing whether comparing with all of the
457 /// incoming phi values yields the same result every time. If so returns the
458 /// common result, otherwise returns null.
459 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
460 const TargetData *TD, const DominatorTree *DT,
461 unsigned MaxRecurse) {
462 // Recursion is always used, so bail out at once if we already hit the limit.
466 // Make sure the phi is on the LHS.
467 if (!isa<PHINode>(LHS)) {
469 Pred = CmpInst::getSwappedPredicate(Pred);
471 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
472 PHINode *PI = cast<PHINode>(LHS);
474 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
475 if (!ValueDominatesPHI(RHS, PI, DT))
478 // Evaluate the BinOp on the incoming phi values.
479 Value *CommonValue = 0;
480 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
481 Value *Incoming = PI->getIncomingValue(i);
482 // If the incoming value is the phi node itself, it can safely be skipped.
483 if (Incoming == PI) continue;
484 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse);
485 // If the operation failed to simplify, or simplified to a different value
486 // to previously, then give up.
487 if (!V || (CommonValue && V != CommonValue))
495 /// SimplifyAddInst - Given operands for an Add, see if we can
496 /// fold the result. If not, this returns null.
497 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
498 const TargetData *TD, const DominatorTree *DT,
499 unsigned MaxRecurse) {
500 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
501 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
502 Constant *Ops[] = { CLHS, CRHS };
503 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
507 // Canonicalize the constant to the RHS.
511 // X + undef -> undef
512 if (isa<UndefValue>(Op1))
516 if (match(Op1, m_Zero()))
523 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
524 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
527 // X + ~X -> -1 since ~X = -X-1
528 if (match(Op0, m_Not(m_Specific(Op1))) ||
529 match(Op1, m_Not(m_Specific(Op0))))
530 return Constant::getAllOnesValue(Op0->getType());
533 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
534 if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
537 // Try some generic simplifications for associative operations.
538 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT,
542 // Mul distributes over Add. Try some generic simplifications based on this.
543 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
547 // Threading Add over selects and phi nodes is pointless, so don't bother.
548 // Threading over the select in "A + select(cond, B, C)" means evaluating
549 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
550 // only if B and C are equal. If B and C are equal then (since we assume
551 // that operands have already been simplified) "select(cond, B, C)" should
552 // have been simplified to the common value of B and C already. Analysing
553 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
554 // for threading over phi nodes.
559 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
560 const TargetData *TD, const DominatorTree *DT) {
561 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
564 /// SimplifySubInst - Given operands for a Sub, see if we can
565 /// fold the result. If not, this returns null.
566 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
567 const TargetData *TD, const DominatorTree *DT,
568 unsigned MaxRecurse) {
569 if (Constant *CLHS = dyn_cast<Constant>(Op0))
570 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
571 Constant *Ops[] = { CLHS, CRHS };
572 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
576 // X - undef -> undef
577 // undef - X -> undef
578 if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1))
579 return UndefValue::get(Op0->getType());
582 if (match(Op1, m_Zero()))
587 return Constant::getNullValue(Op0->getType());
592 if (match(Op0, m_Add(m_Value(X), m_Specific(Op1))) ||
593 match(Op0, m_Add(m_Specific(Op1), m_Value(X))))
597 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
598 if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
601 // Mul distributes over Sub. Try some generic simplifications based on this.
602 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
606 // Threading Sub over selects and phi nodes is pointless, so don't bother.
607 // Threading over the select in "A - select(cond, B, C)" means evaluating
608 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
609 // only if B and C are equal. If B and C are equal then (since we assume
610 // that operands have already been simplified) "select(cond, B, C)" should
611 // have been simplified to the common value of B and C already. Analysing
612 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
613 // for threading over phi nodes.
618 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
619 const TargetData *TD, const DominatorTree *DT) {
620 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
623 /// SimplifyMulInst - Given operands for a Mul, see if we can
624 /// fold the result. If not, this returns null.
625 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
626 const DominatorTree *DT, unsigned MaxRecurse) {
627 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
628 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
629 Constant *Ops[] = { CLHS, CRHS };
630 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
634 // Canonicalize the constant to the RHS.
639 if (isa<UndefValue>(Op1))
640 return Constant::getNullValue(Op0->getType());
643 if (match(Op1, m_Zero()))
647 if (match(Op1, m_One()))
651 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
652 if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1))
655 // Try some generic simplifications for associative operations.
656 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
660 // Mul distributes over Add. Try some generic simplifications based on this.
661 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
665 // If the operation is with the result of a select instruction, check whether
666 // operating on either branch of the select always yields the same value.
667 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
668 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
672 // If the operation is with the result of a phi instruction, check whether
673 // operating on all incoming values of the phi always yields the same value.
674 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
675 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
682 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
683 const DominatorTree *DT) {
684 return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
687 /// SimplifyAndInst - Given operands for an And, see if we can
688 /// fold the result. If not, this returns null.
689 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
690 const DominatorTree *DT, unsigned MaxRecurse) {
691 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
692 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
693 Constant *Ops[] = { CLHS, CRHS };
694 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
698 // Canonicalize the constant to the RHS.
703 if (isa<UndefValue>(Op1))
704 return Constant::getNullValue(Op0->getType());
711 if (match(Op1, m_Zero()))
715 if (match(Op1, m_AllOnes()))
718 // A & ~A = ~A & A = 0
719 Value *A = 0, *B = 0;
720 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
721 (match(Op1, m_Not(m_Value(A))) && A == Op0))
722 return Constant::getNullValue(Op0->getType());
725 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
726 (A == Op1 || B == Op1))
730 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
731 (A == Op0 || B == Op0))
734 // Try some generic simplifications for associative operations.
735 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT,
739 // And distributes over Or. Try some generic simplifications based on this.
740 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
744 // And distributes over Xor. Try some generic simplifications based on this.
745 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
749 // Or distributes over And. Try some generic simplifications based on this.
750 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
754 // If the operation is with the result of a select instruction, check whether
755 // operating on either branch of the select always yields the same value.
756 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
757 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
761 // If the operation is with the result of a phi instruction, check whether
762 // operating on all incoming values of the phi always yields the same value.
763 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
764 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
771 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
772 const DominatorTree *DT) {
773 return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit);
776 /// SimplifyOrInst - Given operands for an Or, see if we can
777 /// fold the result. If not, this returns null.
778 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
779 const DominatorTree *DT, unsigned MaxRecurse) {
780 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
781 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
782 Constant *Ops[] = { CLHS, CRHS };
783 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
787 // Canonicalize the constant to the RHS.
792 if (isa<UndefValue>(Op1))
793 return Constant::getAllOnesValue(Op0->getType());
800 if (match(Op1, m_Zero()))
804 if (match(Op1, m_AllOnes()))
807 // A | ~A = ~A | A = -1
808 Value *A = 0, *B = 0;
809 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
810 (match(Op1, m_Not(m_Value(A))) && A == Op0))
811 return Constant::getAllOnesValue(Op0->getType());
814 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
815 (A == Op1 || B == Op1))
819 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
820 (A == Op0 || B == Op0))
823 // Try some generic simplifications for associative operations.
824 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT,
828 // Or distributes over And. Try some generic simplifications based on this.
829 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And,
833 // And distributes over Or. Try some generic simplifications based on this.
834 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
838 // If the operation is with the result of a select instruction, check whether
839 // operating on either branch of the select always yields the same value.
840 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
841 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
845 // If the operation is with the result of a phi instruction, check whether
846 // operating on all incoming values of the phi always yields the same value.
847 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
848 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
855 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
856 const DominatorTree *DT) {
857 return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
860 /// SimplifyXorInst - Given operands for a Xor, see if we can
861 /// fold the result. If not, this returns null.
862 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
863 const DominatorTree *DT, unsigned MaxRecurse) {
864 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
865 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
866 Constant *Ops[] = { CLHS, CRHS };
867 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
871 // Canonicalize the constant to the RHS.
875 // A ^ undef -> undef
876 if (isa<UndefValue>(Op1))
880 if (match(Op1, m_Zero()))
885 return Constant::getNullValue(Op0->getType());
887 // A ^ ~A = ~A ^ A = -1
889 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
890 (match(Op1, m_Not(m_Value(A))) && A == Op0))
891 return Constant::getAllOnesValue(Op0->getType());
893 // Try some generic simplifications for associative operations.
894 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT,
898 // And distributes over Xor. Try some generic simplifications based on this.
899 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
903 // Threading Xor over selects and phi nodes is pointless, so don't bother.
904 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
905 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
906 // only if B and C are equal. If B and C are equal then (since we assume
907 // that operands have already been simplified) "select(cond, B, C)" should
908 // have been simplified to the common value of B and C already. Analysing
909 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
910 // for threading over phi nodes.
915 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
916 const DominatorTree *DT) {
917 return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
920 static const Type *GetCompareTy(Value *Op) {
921 return CmpInst::makeCmpResultType(Op->getType());
924 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
925 /// fold the result. If not, this returns null.
926 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
927 const TargetData *TD, const DominatorTree *DT,
928 unsigned MaxRecurse) {
929 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
930 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
932 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
933 if (Constant *CRHS = dyn_cast<Constant>(RHS))
934 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
936 // If we have a constant, make sure it is on the RHS.
938 Pred = CmpInst::getSwappedPredicate(Pred);
941 // ITy - This is the return type of the compare we're considering.
942 const Type *ITy = GetCompareTy(LHS);
944 // icmp X, X -> true/false
945 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
946 // because X could be 0.
947 if (LHS == RHS || isa<UndefValue>(RHS))
948 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
950 // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
951 // addresses never equal each other! We already know that Op0 != Op1.
952 if ((isa<GlobalValue>(LHS) || isa<AllocaInst>(LHS) ||
953 isa<ConstantPointerNull>(LHS)) &&
954 (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
955 isa<ConstantPointerNull>(RHS)))
956 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
958 // See if we are doing a comparison with a constant.
959 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
960 // If we have an icmp le or icmp ge instruction, turn it into the
961 // appropriate icmp lt or icmp gt instruction. This allows us to rely on
962 // them being folded in the code below.
965 case ICmpInst::ICMP_ULE:
966 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
967 return ConstantInt::getTrue(CI->getContext());
969 case ICmpInst::ICMP_SLE:
970 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
971 return ConstantInt::getTrue(CI->getContext());
973 case ICmpInst::ICMP_UGE:
974 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
975 return ConstantInt::getTrue(CI->getContext());
977 case ICmpInst::ICMP_SGE:
978 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
979 return ConstantInt::getTrue(CI->getContext());
984 // If the comparison is with the result of a select instruction, check whether
985 // comparing with either branch of the select always yields the same value.
986 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
987 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
990 // If the comparison is with the result of a phi instruction, check whether
991 // doing the compare with each incoming phi value yields a common result.
992 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
993 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
999 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1000 const TargetData *TD, const DominatorTree *DT) {
1001 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1004 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
1005 /// fold the result. If not, this returns null.
1006 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1007 const TargetData *TD, const DominatorTree *DT,
1008 unsigned MaxRecurse) {
1009 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1010 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
1012 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1013 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1014 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
1016 // If we have a constant, make sure it is on the RHS.
1017 std::swap(LHS, RHS);
1018 Pred = CmpInst::getSwappedPredicate(Pred);
1021 // Fold trivial predicates.
1022 if (Pred == FCmpInst::FCMP_FALSE)
1023 return ConstantInt::get(GetCompareTy(LHS), 0);
1024 if (Pred == FCmpInst::FCMP_TRUE)
1025 return ConstantInt::get(GetCompareTy(LHS), 1);
1027 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
1028 return UndefValue::get(GetCompareTy(LHS));
1030 // fcmp x,x -> true/false. Not all compares are foldable.
1032 if (CmpInst::isTrueWhenEqual(Pred))
1033 return ConstantInt::get(GetCompareTy(LHS), 1);
1034 if (CmpInst::isFalseWhenEqual(Pred))
1035 return ConstantInt::get(GetCompareTy(LHS), 0);
1038 // Handle fcmp with constant RHS
1039 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1040 // If the constant is a nan, see if we can fold the comparison based on it.
1041 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1042 if (CFP->getValueAPF().isNaN()) {
1043 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
1044 return ConstantInt::getFalse(CFP->getContext());
1045 assert(FCmpInst::isUnordered(Pred) &&
1046 "Comparison must be either ordered or unordered!");
1047 // True if unordered.
1048 return ConstantInt::getTrue(CFP->getContext());
1050 // Check whether the constant is an infinity.
1051 if (CFP->getValueAPF().isInfinity()) {
1052 if (CFP->getValueAPF().isNegative()) {
1054 case FCmpInst::FCMP_OLT:
1055 // No value is ordered and less than negative infinity.
1056 return ConstantInt::getFalse(CFP->getContext());
1057 case FCmpInst::FCMP_UGE:
1058 // All values are unordered with or at least negative infinity.
1059 return ConstantInt::getTrue(CFP->getContext());
1065 case FCmpInst::FCMP_OGT:
1066 // No value is ordered and greater than infinity.
1067 return ConstantInt::getFalse(CFP->getContext());
1068 case FCmpInst::FCMP_ULE:
1069 // All values are unordered with and at most infinity.
1070 return ConstantInt::getTrue(CFP->getContext());
1079 // If the comparison is with the result of a select instruction, check whether
1080 // comparing with either branch of the select always yields the same value.
1081 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1082 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1085 // If the comparison is with the result of a phi instruction, check whether
1086 // doing the compare with each incoming phi value yields a common result.
1087 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1088 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1094 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1095 const TargetData *TD, const DominatorTree *DT) {
1096 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1099 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
1100 /// the result. If not, this returns null.
1101 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
1102 const TargetData *TD, const DominatorTree *) {
1103 // select true, X, Y -> X
1104 // select false, X, Y -> Y
1105 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
1106 return CB->getZExtValue() ? TrueVal : FalseVal;
1108 // select C, X, X -> X
1109 if (TrueVal == FalseVal)
1112 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
1114 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
1116 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
1117 if (isa<Constant>(TrueVal))
1125 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
1126 /// fold the result. If not, this returns null.
1127 Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
1128 const TargetData *TD, const DominatorTree *) {
1129 // The type of the GEP pointer operand.
1130 const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
1132 // getelementptr P -> P.
1136 if (isa<UndefValue>(Ops[0])) {
1137 // Compute the (pointer) type returned by the GEP instruction.
1138 const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
1140 const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
1141 return UndefValue::get(GEPTy);
1145 // getelementptr P, 0 -> P.
1146 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
1149 // getelementptr P, N -> P if P points to a type of zero size.
1151 const Type *Ty = PtrTy->getElementType();
1152 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
1157 // Check to see if this is constant foldable.
1158 for (unsigned i = 0; i != NumOps; ++i)
1159 if (!isa<Constant>(Ops[i]))
1162 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
1163 (Constant *const*)Ops+1, NumOps-1);
1166 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
1167 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
1168 // If all of the PHI's incoming values are the same then replace the PHI node
1169 // with the common value.
1170 Value *CommonValue = 0;
1171 bool HasUndefInput = false;
1172 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1173 Value *Incoming = PN->getIncomingValue(i);
1174 // If the incoming value is the phi node itself, it can safely be skipped.
1175 if (Incoming == PN) continue;
1176 if (isa<UndefValue>(Incoming)) {
1177 // Remember that we saw an undef value, but otherwise ignore them.
1178 HasUndefInput = true;
1181 if (CommonValue && Incoming != CommonValue)
1182 return 0; // Not the same, bail out.
1183 CommonValue = Incoming;
1186 // If CommonValue is null then all of the incoming values were either undef or
1187 // equal to the phi node itself.
1189 return UndefValue::get(PN->getType());
1191 // If we have a PHI node like phi(X, undef, X), where X is defined by some
1192 // instruction, we cannot return X as the result of the PHI node unless it
1193 // dominates the PHI block.
1195 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
1201 //=== Helper functions for higher up the class hierarchy.
1203 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
1204 /// fold the result. If not, this returns null.
1205 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1206 const TargetData *TD, const DominatorTree *DT,
1207 unsigned MaxRecurse) {
1209 case Instruction::Add: return SimplifyAddInst(LHS, RHS, /* isNSW */ false,
1210 /* isNUW */ false, TD, DT,
1212 case Instruction::Sub: return SimplifySubInst(LHS, RHS, /* isNSW */ false,
1213 /* isNUW */ false, TD, DT,
1215 case Instruction::Mul: return SimplifyMulInst(LHS, RHS, TD, DT, MaxRecurse);
1216 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
1217 case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
1218 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
1220 if (Constant *CLHS = dyn_cast<Constant>(LHS))
1221 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
1222 Constant *COps[] = {CLHS, CRHS};
1223 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
1226 // If the operation is associative, try some generic simplifications.
1227 if (Instruction::isAssociative(Opcode))
1228 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT,
1232 // If the operation is with the result of a select instruction, check whether
1233 // operating on either branch of the select always yields the same value.
1234 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1235 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
1239 // If the operation is with the result of a phi instruction, check whether
1240 // operating on all incoming values of the phi always yields the same value.
1241 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1242 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse))
1249 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1250 const TargetData *TD, const DominatorTree *DT) {
1251 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit);
1254 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
1255 /// fold the result.
1256 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1257 const TargetData *TD, const DominatorTree *DT,
1258 unsigned MaxRecurse) {
1259 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
1260 return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1261 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1264 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1265 const TargetData *TD, const DominatorTree *DT) {
1266 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1269 /// SimplifyInstruction - See if we can compute a simplified version of this
1270 /// instruction. If not, this returns null.
1271 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
1272 const DominatorTree *DT) {
1275 switch (I->getOpcode()) {
1277 Result = ConstantFoldInstruction(I, TD);
1279 case Instruction::Add:
1280 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
1281 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1282 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1285 case Instruction::Sub:
1286 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
1287 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1288 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1291 case Instruction::Mul:
1292 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
1294 case Instruction::And:
1295 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
1297 case Instruction::Or:
1298 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1300 case Instruction::Xor:
1301 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
1303 case Instruction::ICmp:
1304 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
1305 I->getOperand(0), I->getOperand(1), TD, DT);
1307 case Instruction::FCmp:
1308 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
1309 I->getOperand(0), I->getOperand(1), TD, DT);
1311 case Instruction::Select:
1312 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
1313 I->getOperand(2), TD, DT);
1315 case Instruction::GetElementPtr: {
1316 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
1317 Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
1320 case Instruction::PHI:
1321 Result = SimplifyPHINode(cast<PHINode>(I), DT);
1325 /// If called on unreachable code, the above logic may report that the
1326 /// instruction simplified to itself. Make life easier for users by
1327 /// detecting that case here, returning a safe value instead.
1328 return Result == I ? UndefValue::get(I->getType()) : Result;
1331 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
1332 /// delete the From instruction. In addition to a basic RAUW, this does a
1333 /// recursive simplification of the newly formed instructions. This catches
1334 /// things where one simplification exposes other opportunities. This only
1335 /// simplifies and deletes scalar operations, it does not change the CFG.
1337 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
1338 const TargetData *TD,
1339 const DominatorTree *DT) {
1340 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
1342 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
1343 // we can know if it gets deleted out from under us or replaced in a
1344 // recursive simplification.
1345 WeakVH FromHandle(From);
1346 WeakVH ToHandle(To);
1348 while (!From->use_empty()) {
1349 // Update the instruction to use the new value.
1350 Use &TheUse = From->use_begin().getUse();
1351 Instruction *User = cast<Instruction>(TheUse.getUser());
1354 // Check to see if the instruction can be folded due to the operand
1355 // replacement. For example changing (or X, Y) into (or X, -1) can replace
1356 // the 'or' with -1.
1357 Value *SimplifiedVal;
1359 // Sanity check to make sure 'User' doesn't dangle across
1360 // SimplifyInstruction.
1361 AssertingVH<> UserHandle(User);
1363 SimplifiedVal = SimplifyInstruction(User, TD, DT);
1364 if (SimplifiedVal == 0) continue;
1367 // Recursively simplify this user to the new value.
1368 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT);
1369 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
1372 assert(ToHandle && "To value deleted by recursive simplification?");
1374 // If the recursive simplification ended up revisiting and deleting
1375 // 'From' then we're done.
1380 // If 'From' has value handles referring to it, do a real RAUW to update them.
1381 From->replaceAllUsesWith(To);
1383 From->eraseFromParent();