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/Analysis/ValueTracking.h"
26 #include "llvm/Support/PatternMatch.h"
27 #include "llvm/Support/ValueHandle.h"
28 #include "llvm/Target/TargetData.h"
30 using namespace llvm::PatternMatch;
32 enum { RecursionLimit = 3 };
34 STATISTIC(NumExpand, "Number of expansions");
35 STATISTIC(NumFactor , "Number of factorizations");
36 STATISTIC(NumReassoc, "Number of reassociations");
38 static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
39 const DominatorTree *, unsigned);
40 static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
41 const DominatorTree *, unsigned);
42 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
43 const DominatorTree *, unsigned);
44 static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
45 const DominatorTree *, unsigned);
46 static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
47 const DominatorTree *, unsigned);
49 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
50 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
51 Instruction *I = dyn_cast<Instruction>(V);
53 // Arguments and constants dominate all instructions.
56 // If we have a DominatorTree then do a precise test.
58 return DT->dominates(I, P);
60 // Otherwise, if the instruction is in the entry block, and is not an invoke,
61 // then it obviously dominates all phi nodes.
62 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
69 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
70 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
71 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
72 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
73 /// Returns the simplified value, or null if no simplification was performed.
74 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
75 unsigned OpcToExpand, const TargetData *TD,
76 const DominatorTree *DT, unsigned MaxRecurse) {
77 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
78 // Recursion is always used, so bail out at once if we already hit the limit.
82 // Check whether the expression has the form "(A op' B) op C".
83 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
84 if (Op0->getOpcode() == OpcodeToExpand) {
85 // It does! Try turning it into "(A op C) op' (B op C)".
86 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
87 // Do "A op C" and "B op C" both simplify?
88 if (Value *L = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse))
89 if (Value *R = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
90 // They do! Return "L op' R" if it simplifies or is already available.
91 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
92 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
93 && L == B && R == A)) {
97 // Otherwise return "L op' R" if it simplifies.
98 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
106 // Check whether the expression has the form "A op (B op' C)".
107 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
108 if (Op1->getOpcode() == OpcodeToExpand) {
109 // It does! Try turning it into "(A op B) op' (A op C)".
110 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
111 // Do "A op B" and "A op C" both simplify?
112 if (Value *L = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse))
113 if (Value *R = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse)) {
114 // They do! Return "L op' R" if it simplifies or is already available.
115 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
116 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
117 && L == C && R == B)) {
121 // Otherwise return "L op' R" if it simplifies.
122 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
133 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
134 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
135 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
136 /// Returns the simplified value, or null if no simplification was performed.
137 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
138 unsigned OpcToExtract, const TargetData *TD,
139 const DominatorTree *DT, unsigned MaxRecurse) {
140 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
141 // Recursion is always used, so bail out at once if we already hit the limit.
145 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
146 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
148 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
149 !Op1 || Op1->getOpcode() != OpcodeToExtract)
152 // The expression has the form "(A op' B) op (C op' D)".
153 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
154 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
156 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
157 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
158 // commutative case, "(A op' B) op (C op' A)"?
159 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
160 Value *DD = A == C ? D : C;
161 // Form "A op' (B op DD)" if it simplifies completely.
162 // Does "B op DD" simplify?
163 if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, DT, MaxRecurse)) {
164 // It does! Return "A op' V" if it simplifies or is already available.
165 // If V equals B then "A op' V" is just the LHS. If V equals DD then
166 // "A op' V" is just the RHS.
167 if (V == B || V == DD) {
169 return V == B ? LHS : RHS;
171 // Otherwise return "A op' V" if it simplifies.
172 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, DT, MaxRecurse)) {
179 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
180 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
181 // commutative case, "(A op' B) op (B op' D)"?
182 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
183 Value *CC = B == D ? C : D;
184 // Form "(A op CC) op' B" if it simplifies completely..
185 // Does "A op CC" simplify?
186 if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, DT, MaxRecurse)) {
187 // It does! Return "V op' B" if it simplifies or is already available.
188 // If V equals A then "V op' B" is just the LHS. If V equals CC then
189 // "V op' B" is just the RHS.
190 if (V == A || V == CC) {
192 return V == A ? LHS : RHS;
194 // Otherwise return "V op' B" if it simplifies.
195 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, DT, MaxRecurse)) {
205 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
206 /// operations. Returns the simpler value, or null if none was found.
207 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
208 const TargetData *TD,
209 const DominatorTree *DT,
210 unsigned MaxRecurse) {
211 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
212 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
214 // Recursion is always used, so bail out at once if we already hit the limit.
218 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
219 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
221 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
222 if (Op0 && Op0->getOpcode() == Opcode) {
223 Value *A = Op0->getOperand(0);
224 Value *B = Op0->getOperand(1);
227 // Does "B op C" simplify?
228 if (Value *V = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
229 // It does! Return "A op V" if it simplifies or is already available.
230 // If V equals B then "A op V" is just the LHS.
231 if (V == B) return LHS;
232 // Otherwise return "A op V" if it simplifies.
233 if (Value *W = SimplifyBinOp(Opcode, A, V, TD, DT, MaxRecurse)) {
240 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
241 if (Op1 && Op1->getOpcode() == Opcode) {
243 Value *B = Op1->getOperand(0);
244 Value *C = Op1->getOperand(1);
246 // Does "A op B" simplify?
247 if (Value *V = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse)) {
248 // It does! Return "V op C" if it simplifies or is already available.
249 // If V equals B then "V op C" is just the RHS.
250 if (V == B) return RHS;
251 // Otherwise return "V op C" if it simplifies.
252 if (Value *W = SimplifyBinOp(Opcode, V, C, TD, DT, MaxRecurse)) {
259 // The remaining transforms require commutativity as well as associativity.
260 if (!Instruction::isCommutative(Opcode))
263 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
264 if (Op0 && Op0->getOpcode() == Opcode) {
265 Value *A = Op0->getOperand(0);
266 Value *B = Op0->getOperand(1);
269 // Does "C op A" simplify?
270 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
271 // It does! Return "V op B" if it simplifies or is already available.
272 // If V equals A then "V op B" is just the LHS.
273 if (V == A) return LHS;
274 // Otherwise return "V op B" if it simplifies.
275 if (Value *W = SimplifyBinOp(Opcode, V, B, TD, DT, MaxRecurse)) {
282 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
283 if (Op1 && Op1->getOpcode() == Opcode) {
285 Value *B = Op1->getOperand(0);
286 Value *C = Op1->getOperand(1);
288 // Does "C op A" simplify?
289 if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
290 // It does! Return "B op V" if it simplifies or is already available.
291 // If V equals C then "B op V" is just the RHS.
292 if (V == C) return RHS;
293 // Otherwise return "B op V" if it simplifies.
294 if (Value *W = SimplifyBinOp(Opcode, B, V, TD, DT, MaxRecurse)) {
304 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
305 /// instruction as an operand, try to simplify the binop by seeing whether
306 /// evaluating it on both branches of the select results in the same value.
307 /// Returns the common value if so, otherwise returns null.
308 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
309 const TargetData *TD,
310 const DominatorTree *DT,
311 unsigned MaxRecurse) {
312 // Recursion is always used, so bail out at once if we already hit the limit.
317 if (isa<SelectInst>(LHS)) {
318 SI = cast<SelectInst>(LHS);
320 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
321 SI = cast<SelectInst>(RHS);
324 // Evaluate the BinOp on the true and false branches of the select.
328 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, DT, MaxRecurse);
329 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, DT, MaxRecurse);
331 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, DT, MaxRecurse);
332 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, DT, MaxRecurse);
335 // If they simplified to the same value, then return the common value.
336 // If they both failed to simplify then return null.
340 // If one branch simplified to undef, return the other one.
341 if (TV && isa<UndefValue>(TV))
343 if (FV && isa<UndefValue>(FV))
346 // If applying the operation did not change the true and false select values,
347 // then the result of the binop is the select itself.
348 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
351 // If one branch simplified and the other did not, and the simplified
352 // value is equal to the unsimplified one, return the simplified value.
353 // For example, select (cond, X, X & Z) & Z -> X & Z.
354 if ((FV && !TV) || (TV && !FV)) {
355 // Check that the simplified value has the form "X op Y" where "op" is the
356 // same as the original operation.
357 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
358 if (Simplified && Simplified->getOpcode() == Opcode) {
359 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
360 // We already know that "op" is the same as for the simplified value. See
361 // if the operands match too. If so, return the simplified value.
362 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
363 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
364 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
365 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
366 Simplified->getOperand(1) == UnsimplifiedRHS)
368 if (Simplified->isCommutative() &&
369 Simplified->getOperand(1) == UnsimplifiedLHS &&
370 Simplified->getOperand(0) == UnsimplifiedRHS)
378 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
379 /// try to simplify the comparison by seeing whether both branches of the select
380 /// result in the same value. Returns the common value if so, otherwise returns
382 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
383 Value *RHS, const TargetData *TD,
384 const DominatorTree *DT,
385 unsigned MaxRecurse) {
386 // Recursion is always used, so bail out at once if we already hit the limit.
390 // Make sure the select is on the LHS.
391 if (!isa<SelectInst>(LHS)) {
393 Pred = CmpInst::getSwappedPredicate(Pred);
395 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
396 SelectInst *SI = cast<SelectInst>(LHS);
398 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
399 // Does "cmp TV, RHS" simplify?
400 if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT,
402 // It does! Does "cmp FV, RHS" simplify?
403 if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT,
405 // It does! If they simplified to the same value, then use it as the
406 // result of the original comparison.
409 Value *Cond = SI->getCondition();
410 // If the false value simplified to false, then the result of the compare
411 // is equal to "Cond && TCmp". This also catches the case when the false
412 // value simplified to false and the true value to true, returning "Cond".
413 if (match(FCmp, m_Zero()))
414 if (Value *V = SimplifyAndInst(Cond, TCmp, TD, DT, MaxRecurse))
416 // If the true value simplified to true, then the result of the compare
417 // is equal to "Cond || FCmp".
418 if (match(TCmp, m_One()))
419 if (Value *V = SimplifyOrInst(Cond, FCmp, TD, DT, MaxRecurse))
421 // Finally, if the false value simplified to true and the true value to
422 // false, then the result of the compare is equal to "!Cond".
423 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
425 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
434 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
435 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
436 /// it on the incoming phi values yields the same result for every value. If so
437 /// returns the common value, otherwise returns null.
438 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
439 const TargetData *TD, const DominatorTree *DT,
440 unsigned MaxRecurse) {
441 // Recursion is always used, so bail out at once if we already hit the limit.
446 if (isa<PHINode>(LHS)) {
447 PI = cast<PHINode>(LHS);
448 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
449 if (!ValueDominatesPHI(RHS, PI, DT))
452 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
453 PI = cast<PHINode>(RHS);
454 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
455 if (!ValueDominatesPHI(LHS, PI, DT))
459 // Evaluate the BinOp on the incoming phi values.
460 Value *CommonValue = 0;
461 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
462 Value *Incoming = PI->getIncomingValue(i);
463 // If the incoming value is the phi node itself, it can safely be skipped.
464 if (Incoming == PI) continue;
465 Value *V = PI == LHS ?
466 SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) :
467 SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, MaxRecurse);
468 // If the operation failed to simplify, or simplified to a different value
469 // to previously, then give up.
470 if (!V || (CommonValue && V != CommonValue))
478 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
479 /// try to simplify the comparison by seeing whether comparing with all of the
480 /// incoming phi values yields the same result every time. If so returns the
481 /// common result, otherwise returns null.
482 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
483 const TargetData *TD, const DominatorTree *DT,
484 unsigned MaxRecurse) {
485 // Recursion is always used, so bail out at once if we already hit the limit.
489 // Make sure the phi is on the LHS.
490 if (!isa<PHINode>(LHS)) {
492 Pred = CmpInst::getSwappedPredicate(Pred);
494 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
495 PHINode *PI = cast<PHINode>(LHS);
497 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
498 if (!ValueDominatesPHI(RHS, PI, DT))
501 // Evaluate the BinOp on the incoming phi values.
502 Value *CommonValue = 0;
503 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
504 Value *Incoming = PI->getIncomingValue(i);
505 // If the incoming value is the phi node itself, it can safely be skipped.
506 if (Incoming == PI) continue;
507 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse);
508 // If the operation failed to simplify, or simplified to a different value
509 // to previously, then give up.
510 if (!V || (CommonValue && V != CommonValue))
518 /// SimplifyAddInst - Given operands for an Add, see if we can
519 /// fold the result. If not, this returns null.
520 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
521 const TargetData *TD, const DominatorTree *DT,
522 unsigned MaxRecurse) {
523 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
524 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
525 Constant *Ops[] = { CLHS, CRHS };
526 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
530 // Canonicalize the constant to the RHS.
534 // X + undef -> undef
535 if (match(Op1, m_Undef()))
539 if (match(Op1, m_Zero()))
546 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
547 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
550 // X + ~X -> -1 since ~X = -X-1
551 if (match(Op0, m_Not(m_Specific(Op1))) ||
552 match(Op1, m_Not(m_Specific(Op0))))
553 return Constant::getAllOnesValue(Op0->getType());
556 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
557 if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
560 // Try some generic simplifications for associative operations.
561 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT,
565 // Mul distributes over Add. Try some generic simplifications based on this.
566 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
570 // Threading Add over selects and phi nodes is pointless, so don't bother.
571 // Threading over the select in "A + select(cond, B, C)" means evaluating
572 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
573 // only if B and C are equal. If B and C are equal then (since we assume
574 // that operands have already been simplified) "select(cond, B, C)" should
575 // have been simplified to the common value of B and C already. Analysing
576 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
577 // for threading over phi nodes.
582 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
583 const TargetData *TD, const DominatorTree *DT) {
584 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
587 /// SimplifySubInst - Given operands for a Sub, see if we can
588 /// fold the result. If not, this returns null.
589 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
590 const TargetData *TD, const DominatorTree *DT,
591 unsigned MaxRecurse) {
592 if (Constant *CLHS = dyn_cast<Constant>(Op0))
593 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
594 Constant *Ops[] = { CLHS, CRHS };
595 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
599 // X - undef -> undef
600 // undef - X -> undef
601 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
602 return UndefValue::get(Op0->getType());
605 if (match(Op1, m_Zero()))
610 return Constant::getNullValue(Op0->getType());
615 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
616 match(Op0, m_Shl(m_Specific(Op1), m_One())))
619 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
620 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
621 Value *Y = 0, *Z = Op1;
622 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
623 // See if "V === Y - Z" simplifies.
624 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, DT, MaxRecurse-1))
625 // It does! Now see if "X + V" simplifies.
626 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, DT,
628 // It does, we successfully reassociated!
632 // See if "V === X - Z" simplifies.
633 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
634 // It does! Now see if "Y + V" simplifies.
635 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, DT,
637 // It does, we successfully reassociated!
643 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
644 // For example, X - (X + 1) -> -1
646 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
647 // See if "V === X - Y" simplifies.
648 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, DT, MaxRecurse-1))
649 // It does! Now see if "V - Z" simplifies.
650 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, DT,
652 // It does, we successfully reassociated!
656 // See if "V === X - Z" simplifies.
657 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
658 // It does! Now see if "V - Y" simplifies.
659 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, DT,
661 // It does, we successfully reassociated!
667 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
668 // For example, X - (X - Y) -> Y.
670 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
671 // See if "V === Z - X" simplifies.
672 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, DT, MaxRecurse-1))
673 // It does! Now see if "V + Y" simplifies.
674 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, DT,
676 // It does, we successfully reassociated!
681 // Mul distributes over Sub. Try some generic simplifications based on this.
682 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
687 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
688 if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
691 // Threading Sub over selects and phi nodes is pointless, so don't bother.
692 // Threading over the select in "A - select(cond, B, C)" means evaluating
693 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
694 // only if B and C are equal. If B and C are equal then (since we assume
695 // that operands have already been simplified) "select(cond, B, C)" should
696 // have been simplified to the common value of B and C already. Analysing
697 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
698 // for threading over phi nodes.
703 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
704 const TargetData *TD, const DominatorTree *DT) {
705 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
708 /// SimplifyMulInst - Given operands for a Mul, see if we can
709 /// fold the result. If not, this returns null.
710 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
711 const DominatorTree *DT, unsigned MaxRecurse) {
712 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
713 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
714 Constant *Ops[] = { CLHS, CRHS };
715 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
719 // Canonicalize the constant to the RHS.
724 if (match(Op1, m_Undef()))
725 return Constant::getNullValue(Op0->getType());
728 if (match(Op1, m_Zero()))
732 if (match(Op1, m_One()))
735 // (X / Y) * Y -> X if the division is exact.
736 Value *X = 0, *Y = 0;
737 if ((match(Op0, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y
738 (match(Op1, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y)
739 BinaryOperator *Div = cast<BinaryOperator>(Y == Op1 ? Op0 : Op1);
745 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
746 if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1))
749 // Try some generic simplifications for associative operations.
750 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
754 // Mul distributes over Add. Try some generic simplifications based on this.
755 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
759 // If the operation is with the result of a select instruction, check whether
760 // operating on either branch of the select always yields the same value.
761 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
762 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
766 // If the operation is with the result of a phi instruction, check whether
767 // operating on all incoming values of the phi always yields the same value.
768 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
769 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
776 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
777 const DominatorTree *DT) {
778 return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
781 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
782 /// fold the result. If not, this returns null.
783 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
784 const TargetData *TD, const DominatorTree *DT,
785 unsigned MaxRecurse) {
786 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
787 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
788 Constant *Ops[] = { C0, C1 };
789 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
793 bool isSigned = Opcode == Instruction::SDiv;
795 // X / undef -> undef
796 if (match(Op1, m_Undef()))
800 if (match(Op0, m_Undef()))
801 return Constant::getNullValue(Op0->getType());
803 // 0 / X -> 0, we don't need to preserve faults!
804 if (match(Op0, m_Zero()))
808 if (match(Op1, m_One()))
811 if (Op0->getType()->isIntegerTy(1))
812 // It can't be division by zero, hence it must be division by one.
817 return ConstantInt::get(Op0->getType(), 1);
819 // (X * Y) / Y -> X if the multiplication does not overflow.
820 Value *X = 0, *Y = 0;
821 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
822 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
823 BinaryOperator *Mul = cast<BinaryOperator>(Op0);
824 // If the Mul knows it does not overflow, then we are good to go.
825 if ((isSigned && Mul->hasNoSignedWrap()) ||
826 (!isSigned && Mul->hasNoUnsignedWrap()))
828 // If X has the form X = A / Y then X * Y cannot overflow.
829 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
830 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
834 // (X rem Y) / Y -> 0
835 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
836 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
837 return Constant::getNullValue(Op0->getType());
839 // If the operation is with the result of a select instruction, check whether
840 // operating on either branch of the select always yields the same value.
841 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
842 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
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(Opcode, Op0, Op1, TD, DT, MaxRecurse))
854 /// SimplifySDivInst - Given operands for an SDiv, see if we can
855 /// fold the result. If not, this returns null.
856 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
857 const DominatorTree *DT, unsigned MaxRecurse) {
858 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, DT, MaxRecurse))
864 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
865 const DominatorTree *DT) {
866 return ::SimplifySDivInst(Op0, Op1, TD, DT, RecursionLimit);
869 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
870 /// fold the result. If not, this returns null.
871 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
872 const DominatorTree *DT, unsigned MaxRecurse) {
873 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, DT, MaxRecurse))
879 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
880 const DominatorTree *DT) {
881 return ::SimplifyUDivInst(Op0, Op1, TD, DT, RecursionLimit);
884 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *,
885 const DominatorTree *, unsigned) {
886 // undef / X -> undef (the undef could be a snan).
887 if (match(Op0, m_Undef()))
890 // X / undef -> undef
891 if (match(Op1, m_Undef()))
897 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
898 const DominatorTree *DT) {
899 return ::SimplifyFDivInst(Op0, Op1, TD, DT, RecursionLimit);
902 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
903 /// fold the result. If not, this returns null.
904 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
905 const TargetData *TD, const DominatorTree *DT,
906 unsigned MaxRecurse) {
907 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
908 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
909 Constant *Ops[] = { C0, C1 };
910 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
915 if (match(Op0, m_Zero()))
919 if (match(Op1, m_Zero()))
922 // X shift by undef -> undef because it may shift by the bitwidth.
923 if (match(Op1, m_Undef()))
926 // Shifting by the bitwidth or more is undefined.
927 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
928 if (CI->getValue().getLimitedValue() >=
929 Op0->getType()->getScalarSizeInBits())
930 return UndefValue::get(Op0->getType());
932 // If the operation is with the result of a select instruction, check whether
933 // operating on either branch of the select always yields the same value.
934 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
935 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
938 // If the operation is with the result of a phi instruction, check whether
939 // operating on all incoming values of the phi always yields the same value.
940 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
941 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
947 /// SimplifyShlInst - Given operands for an Shl, see if we can
948 /// fold the result. If not, this returns null.
949 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
950 const TargetData *TD, const DominatorTree *DT,
951 unsigned MaxRecurse) {
952 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, DT, MaxRecurse))
956 if (match(Op0, m_Undef()))
957 return Constant::getNullValue(Op0->getType());
959 // (X >> A) << A -> X
961 if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1))) &&
962 cast<PossiblyExactOperator>(Op0)->isExact())
967 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
968 const TargetData *TD, const DominatorTree *DT) {
969 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
972 /// SimplifyLShrInst - Given operands for an LShr, see if we can
973 /// fold the result. If not, this returns null.
974 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
975 const TargetData *TD, const DominatorTree *DT,
976 unsigned MaxRecurse) {
977 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, DT, MaxRecurse))
981 if (match(Op0, m_Undef()))
982 return Constant::getNullValue(Op0->getType());
984 // (X << A) >> A -> X
986 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
987 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
993 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
994 const TargetData *TD, const DominatorTree *DT) {
995 return ::SimplifyLShrInst(Op0, Op1, isExact, TD, DT, RecursionLimit);
998 /// SimplifyAShrInst - Given operands for an AShr, see if we can
999 /// fold the result. If not, this returns null.
1000 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1001 const TargetData *TD, const DominatorTree *DT,
1002 unsigned MaxRecurse) {
1003 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, DT, MaxRecurse))
1006 // all ones >>a X -> all ones
1007 if (match(Op0, m_AllOnes()))
1010 // undef >>a X -> all ones
1011 if (match(Op0, m_Undef()))
1012 return Constant::getAllOnesValue(Op0->getType());
1014 // (X << A) >> A -> X
1016 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1017 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
1023 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1024 const TargetData *TD, const DominatorTree *DT) {
1025 return ::SimplifyAShrInst(Op0, Op1, isExact, TD, DT, RecursionLimit);
1028 /// SimplifyAndInst - Given operands for an And, see if we can
1029 /// fold the result. If not, this returns null.
1030 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1031 const DominatorTree *DT, unsigned MaxRecurse) {
1032 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1033 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1034 Constant *Ops[] = { CLHS, CRHS };
1035 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1039 // Canonicalize the constant to the RHS.
1040 std::swap(Op0, Op1);
1044 if (match(Op1, m_Undef()))
1045 return Constant::getNullValue(Op0->getType());
1052 if (match(Op1, m_Zero()))
1056 if (match(Op1, m_AllOnes()))
1059 // A & ~A = ~A & A = 0
1060 if (match(Op0, m_Not(m_Specific(Op1))) ||
1061 match(Op1, m_Not(m_Specific(Op0))))
1062 return Constant::getNullValue(Op0->getType());
1065 Value *A = 0, *B = 0;
1066 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1067 (A == Op1 || B == Op1))
1071 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1072 (A == Op0 || B == Op0))
1075 // Try some generic simplifications for associative operations.
1076 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT,
1080 // And distributes over Or. Try some generic simplifications based on this.
1081 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1082 TD, DT, MaxRecurse))
1085 // And distributes over Xor. Try some generic simplifications based on this.
1086 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1087 TD, DT, MaxRecurse))
1090 // Or distributes over And. Try some generic simplifications based on this.
1091 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1092 TD, DT, MaxRecurse))
1095 // If the operation is with the result of a select instruction, check whether
1096 // operating on either branch of the select always yields the same value.
1097 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1098 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
1102 // If the operation is with the result of a phi instruction, check whether
1103 // operating on all incoming values of the phi always yields the same value.
1104 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1105 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
1112 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1113 const DominatorTree *DT) {
1114 return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit);
1117 /// SimplifyOrInst - Given operands for an Or, see if we can
1118 /// fold the result. If not, this returns null.
1119 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1120 const DominatorTree *DT, unsigned MaxRecurse) {
1121 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1122 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1123 Constant *Ops[] = { CLHS, CRHS };
1124 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1128 // Canonicalize the constant to the RHS.
1129 std::swap(Op0, Op1);
1133 if (match(Op1, m_Undef()))
1134 return Constant::getAllOnesValue(Op0->getType());
1141 if (match(Op1, m_Zero()))
1145 if (match(Op1, m_AllOnes()))
1148 // A | ~A = ~A | A = -1
1149 if (match(Op0, m_Not(m_Specific(Op1))) ||
1150 match(Op1, m_Not(m_Specific(Op0))))
1151 return Constant::getAllOnesValue(Op0->getType());
1154 Value *A = 0, *B = 0;
1155 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1156 (A == Op1 || B == Op1))
1160 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1161 (A == Op0 || B == Op0))
1164 // ~(A & ?) | A = -1
1165 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1166 (A == Op1 || B == Op1))
1167 return Constant::getAllOnesValue(Op1->getType());
1169 // A | ~(A & ?) = -1
1170 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1171 (A == Op0 || B == Op0))
1172 return Constant::getAllOnesValue(Op0->getType());
1174 // Try some generic simplifications for associative operations.
1175 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT,
1179 // Or distributes over And. Try some generic simplifications based on this.
1180 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1181 TD, DT, MaxRecurse))
1184 // And distributes over Or. Try some generic simplifications based on this.
1185 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1186 TD, DT, MaxRecurse))
1189 // If the operation is with the result of a select instruction, check whether
1190 // operating on either branch of the select always yields the same value.
1191 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1192 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
1196 // If the operation is with the result of a phi instruction, check whether
1197 // operating on all incoming values of the phi always yields the same value.
1198 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1199 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
1206 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1207 const DominatorTree *DT) {
1208 return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
1211 /// SimplifyXorInst - Given operands for a Xor, see if we can
1212 /// fold the result. If not, this returns null.
1213 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1214 const DominatorTree *DT, unsigned MaxRecurse) {
1215 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1216 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1217 Constant *Ops[] = { CLHS, CRHS };
1218 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1222 // Canonicalize the constant to the RHS.
1223 std::swap(Op0, Op1);
1226 // A ^ undef -> undef
1227 if (match(Op1, m_Undef()))
1231 if (match(Op1, m_Zero()))
1236 return Constant::getNullValue(Op0->getType());
1238 // A ^ ~A = ~A ^ A = -1
1239 if (match(Op0, m_Not(m_Specific(Op1))) ||
1240 match(Op1, m_Not(m_Specific(Op0))))
1241 return Constant::getAllOnesValue(Op0->getType());
1243 // Try some generic simplifications for associative operations.
1244 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT,
1248 // And distributes over Xor. Try some generic simplifications based on this.
1249 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1250 TD, DT, MaxRecurse))
1253 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1254 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1255 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1256 // only if B and C are equal. If B and C are equal then (since we assume
1257 // that operands have already been simplified) "select(cond, B, C)" should
1258 // have been simplified to the common value of B and C already. Analysing
1259 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1260 // for threading over phi nodes.
1265 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1266 const DominatorTree *DT) {
1267 return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
1270 static const Type *GetCompareTy(Value *Op) {
1271 return CmpInst::makeCmpResultType(Op->getType());
1274 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1275 /// fold the result. If not, this returns null.
1276 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1277 const TargetData *TD, const DominatorTree *DT,
1278 unsigned MaxRecurse) {
1279 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1280 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1282 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1283 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1284 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
1286 // If we have a constant, make sure it is on the RHS.
1287 std::swap(LHS, RHS);
1288 Pred = CmpInst::getSwappedPredicate(Pred);
1291 const Type *ITy = GetCompareTy(LHS); // The return type.
1292 const Type *OpTy = LHS->getType(); // The operand type.
1294 // icmp X, X -> true/false
1295 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1296 // because X could be 0.
1297 if (LHS == RHS || isa<UndefValue>(RHS))
1298 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1300 // Special case logic when the operands have i1 type.
1301 if (OpTy->isIntegerTy(1) || (OpTy->isVectorTy() &&
1302 cast<VectorType>(OpTy)->getElementType()->isIntegerTy(1))) {
1305 case ICmpInst::ICMP_EQ:
1307 if (match(RHS, m_One()))
1310 case ICmpInst::ICMP_NE:
1312 if (match(RHS, m_Zero()))
1315 case ICmpInst::ICMP_UGT:
1317 if (match(RHS, m_Zero()))
1320 case ICmpInst::ICMP_UGE:
1322 if (match(RHS, m_One()))
1325 case ICmpInst::ICMP_SLT:
1327 if (match(RHS, m_Zero()))
1330 case ICmpInst::ICMP_SLE:
1332 if (match(RHS, m_One()))
1338 // icmp <alloca*>, <global/alloca*/null> - Different stack variables have
1339 // different addresses, and what's more the address of a stack variable is
1340 // never null or equal to the address of a global. Note that generalizing
1341 // to the case where LHS is a global variable address or null is pointless,
1342 // since if both LHS and RHS are constants then we already constant folded
1343 // the compare, and if only one of them is then we moved it to RHS already.
1344 if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
1345 isa<ConstantPointerNull>(RHS)))
1346 // We already know that LHS != LHS.
1347 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
1349 // If we are comparing with zero then try hard since this is a common case.
1350 if (match(RHS, m_Zero())) {
1351 bool LHSKnownNonNegative, LHSKnownNegative;
1354 assert(false && "Unknown ICmp predicate!");
1355 case ICmpInst::ICMP_ULT:
1356 return ConstantInt::getFalse(LHS->getContext());
1357 case ICmpInst::ICMP_UGE:
1358 return ConstantInt::getTrue(LHS->getContext());
1359 case ICmpInst::ICMP_EQ:
1360 case ICmpInst::ICMP_ULE:
1361 if (isKnownNonZero(LHS, TD))
1362 return ConstantInt::getFalse(LHS->getContext());
1364 case ICmpInst::ICMP_NE:
1365 case ICmpInst::ICMP_UGT:
1366 if (isKnownNonZero(LHS, TD))
1367 return ConstantInt::getTrue(LHS->getContext());
1369 case ICmpInst::ICMP_SLT:
1370 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1371 if (LHSKnownNegative)
1372 return ConstantInt::getTrue(LHS->getContext());
1373 if (LHSKnownNonNegative)
1374 return ConstantInt::getFalse(LHS->getContext());
1376 case ICmpInst::ICMP_SLE:
1377 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1378 if (LHSKnownNegative)
1379 return ConstantInt::getTrue(LHS->getContext());
1380 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1381 return ConstantInt::getFalse(LHS->getContext());
1383 case ICmpInst::ICMP_SGE:
1384 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1385 if (LHSKnownNegative)
1386 return ConstantInt::getFalse(LHS->getContext());
1387 if (LHSKnownNonNegative)
1388 return ConstantInt::getTrue(LHS->getContext());
1390 case ICmpInst::ICMP_SGT:
1391 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1392 if (LHSKnownNegative)
1393 return ConstantInt::getFalse(LHS->getContext());
1394 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1395 return ConstantInt::getTrue(LHS->getContext());
1400 // See if we are doing a comparison with a constant integer.
1401 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1404 case ICmpInst::ICMP_UGT:
1405 if (CI->isMaxValue(false)) // A >u MAX -> FALSE
1406 return ConstantInt::getFalse(CI->getContext());
1408 case ICmpInst::ICMP_UGE:
1409 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
1410 return ConstantInt::getTrue(CI->getContext());
1412 case ICmpInst::ICMP_ULT:
1413 if (CI->isMinValue(false)) // A <u MIN -> FALSE
1414 return ConstantInt::getFalse(CI->getContext());
1416 case ICmpInst::ICMP_ULE:
1417 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
1418 return ConstantInt::getTrue(CI->getContext());
1420 case ICmpInst::ICMP_SGT:
1421 if (CI->isMaxValue(true)) // A >s MAX -> FALSE
1422 return ConstantInt::getFalse(CI->getContext());
1424 case ICmpInst::ICMP_SGE:
1425 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
1426 return ConstantInt::getTrue(CI->getContext());
1428 case ICmpInst::ICMP_SLT:
1429 if (CI->isMinValue(true)) // A <s MIN -> FALSE
1430 return ConstantInt::getFalse(CI->getContext());
1432 case ICmpInst::ICMP_SLE:
1433 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
1434 return ConstantInt::getTrue(CI->getContext());
1439 // Compare of cast, for example (zext X) != 0 -> X != 0
1440 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1441 Instruction *LI = cast<CastInst>(LHS);
1442 Value *SrcOp = LI->getOperand(0);
1443 const Type *SrcTy = SrcOp->getType();
1444 const Type *DstTy = LI->getType();
1446 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1447 // if the integer type is the same size as the pointer type.
1448 if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
1449 TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1450 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1451 // Transfer the cast to the constant.
1452 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1453 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1454 TD, DT, MaxRecurse-1))
1456 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1457 if (RI->getOperand(0)->getType() == SrcTy)
1458 // Compare without the cast.
1459 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1460 TD, DT, MaxRecurse-1))
1465 if (isa<ZExtInst>(LHS)) {
1466 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1468 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1469 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1470 // Compare X and Y. Note that signed predicates become unsigned.
1471 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1472 SrcOp, RI->getOperand(0), TD, DT,
1476 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1477 // too. If not, then try to deduce the result of the comparison.
1478 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1479 // Compute the constant that would happen if we truncated to SrcTy then
1480 // reextended to DstTy.
1481 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1482 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1484 // If the re-extended constant didn't change then this is effectively
1485 // also a case of comparing two zero-extended values.
1486 if (RExt == CI && MaxRecurse)
1487 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1488 SrcOp, Trunc, TD, DT, MaxRecurse-1))
1491 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1492 // there. Use this to work out the result of the comparison.
1496 assert(false && "Unknown ICmp predicate!");
1498 case ICmpInst::ICMP_EQ:
1499 case ICmpInst::ICMP_UGT:
1500 case ICmpInst::ICMP_UGE:
1501 return ConstantInt::getFalse(CI->getContext());
1503 case ICmpInst::ICMP_NE:
1504 case ICmpInst::ICMP_ULT:
1505 case ICmpInst::ICMP_ULE:
1506 return ConstantInt::getTrue(CI->getContext());
1508 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1509 // is non-negative then LHS <s RHS.
1510 case ICmpInst::ICMP_SGT:
1511 case ICmpInst::ICMP_SGE:
1512 return CI->getValue().isNegative() ?
1513 ConstantInt::getTrue(CI->getContext()) :
1514 ConstantInt::getFalse(CI->getContext());
1516 case ICmpInst::ICMP_SLT:
1517 case ICmpInst::ICMP_SLE:
1518 return CI->getValue().isNegative() ?
1519 ConstantInt::getFalse(CI->getContext()) :
1520 ConstantInt::getTrue(CI->getContext());
1526 if (isa<SExtInst>(LHS)) {
1527 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1529 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1530 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1531 // Compare X and Y. Note that the predicate does not change.
1532 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1533 TD, DT, MaxRecurse-1))
1536 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1537 // too. If not, then try to deduce the result of the comparison.
1538 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1539 // Compute the constant that would happen if we truncated to SrcTy then
1540 // reextended to DstTy.
1541 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1542 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1544 // If the re-extended constant didn't change then this is effectively
1545 // also a case of comparing two sign-extended values.
1546 if (RExt == CI && MaxRecurse)
1547 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, DT,
1551 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1552 // bits there. Use this to work out the result of the comparison.
1556 assert(false && "Unknown ICmp predicate!");
1557 case ICmpInst::ICMP_EQ:
1558 return ConstantInt::getFalse(CI->getContext());
1559 case ICmpInst::ICMP_NE:
1560 return ConstantInt::getTrue(CI->getContext());
1562 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1564 case ICmpInst::ICMP_SGT:
1565 case ICmpInst::ICMP_SGE:
1566 return CI->getValue().isNegative() ?
1567 ConstantInt::getTrue(CI->getContext()) :
1568 ConstantInt::getFalse(CI->getContext());
1569 case ICmpInst::ICMP_SLT:
1570 case ICmpInst::ICMP_SLE:
1571 return CI->getValue().isNegative() ?
1572 ConstantInt::getFalse(CI->getContext()) :
1573 ConstantInt::getTrue(CI->getContext());
1575 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
1577 case ICmpInst::ICMP_UGT:
1578 case ICmpInst::ICMP_UGE:
1579 // Comparison is true iff the LHS <s 0.
1581 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
1582 Constant::getNullValue(SrcTy),
1583 TD, DT, MaxRecurse-1))
1586 case ICmpInst::ICMP_ULT:
1587 case ICmpInst::ICMP_ULE:
1588 // Comparison is true iff the LHS >=s 0.
1590 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
1591 Constant::getNullValue(SrcTy),
1592 TD, DT, MaxRecurse-1))
1601 // Special logic for binary operators.
1602 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
1603 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
1604 if (MaxRecurse && (LBO || RBO)) {
1605 // Analyze the case when either LHS or RHS is an add instruction.
1606 Value *A = 0, *B = 0, *C = 0, *D = 0;
1607 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
1608 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
1609 if (LBO && LBO->getOpcode() == Instruction::Add) {
1610 A = LBO->getOperand(0); B = LBO->getOperand(1);
1611 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
1612 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
1613 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
1615 if (RBO && RBO->getOpcode() == Instruction::Add) {
1616 C = RBO->getOperand(0); D = RBO->getOperand(1);
1617 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
1618 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
1619 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
1622 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
1623 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
1624 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
1625 Constant::getNullValue(RHS->getType()),
1626 TD, DT, MaxRecurse-1))
1629 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
1630 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
1631 if (Value *V = SimplifyICmpInst(Pred,
1632 Constant::getNullValue(LHS->getType()),
1633 C == LHS ? D : C, TD, DT, MaxRecurse-1))
1636 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
1637 if (A && C && (A == C || A == D || B == C || B == D) &&
1638 NoLHSWrapProblem && NoRHSWrapProblem) {
1639 // Determine Y and Z in the form icmp (X+Y), (X+Z).
1640 Value *Y = (A == C || A == D) ? B : A;
1641 Value *Z = (C == A || C == B) ? D : C;
1642 if (Value *V = SimplifyICmpInst(Pred, Y, Z, TD, DT, MaxRecurse-1))
1647 // If the comparison is with the result of a select instruction, check whether
1648 // comparing with either branch of the select always yields the same value.
1649 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1650 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1653 // If the comparison is with the result of a phi instruction, check whether
1654 // doing the compare with each incoming phi value yields a common result.
1655 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1656 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1662 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1663 const TargetData *TD, const DominatorTree *DT) {
1664 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1667 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
1668 /// fold the result. If not, this returns null.
1669 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1670 const TargetData *TD, const DominatorTree *DT,
1671 unsigned MaxRecurse) {
1672 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1673 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
1675 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1676 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1677 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
1679 // If we have a constant, make sure it is on the RHS.
1680 std::swap(LHS, RHS);
1681 Pred = CmpInst::getSwappedPredicate(Pred);
1684 // Fold trivial predicates.
1685 if (Pred == FCmpInst::FCMP_FALSE)
1686 return ConstantInt::get(GetCompareTy(LHS), 0);
1687 if (Pred == FCmpInst::FCMP_TRUE)
1688 return ConstantInt::get(GetCompareTy(LHS), 1);
1690 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
1691 return UndefValue::get(GetCompareTy(LHS));
1693 // fcmp x,x -> true/false. Not all compares are foldable.
1695 if (CmpInst::isTrueWhenEqual(Pred))
1696 return ConstantInt::get(GetCompareTy(LHS), 1);
1697 if (CmpInst::isFalseWhenEqual(Pred))
1698 return ConstantInt::get(GetCompareTy(LHS), 0);
1701 // Handle fcmp with constant RHS
1702 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1703 // If the constant is a nan, see if we can fold the comparison based on it.
1704 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1705 if (CFP->getValueAPF().isNaN()) {
1706 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
1707 return ConstantInt::getFalse(CFP->getContext());
1708 assert(FCmpInst::isUnordered(Pred) &&
1709 "Comparison must be either ordered or unordered!");
1710 // True if unordered.
1711 return ConstantInt::getTrue(CFP->getContext());
1713 // Check whether the constant is an infinity.
1714 if (CFP->getValueAPF().isInfinity()) {
1715 if (CFP->getValueAPF().isNegative()) {
1717 case FCmpInst::FCMP_OLT:
1718 // No value is ordered and less than negative infinity.
1719 return ConstantInt::getFalse(CFP->getContext());
1720 case FCmpInst::FCMP_UGE:
1721 // All values are unordered with or at least negative infinity.
1722 return ConstantInt::getTrue(CFP->getContext());
1728 case FCmpInst::FCMP_OGT:
1729 // No value is ordered and greater than infinity.
1730 return ConstantInt::getFalse(CFP->getContext());
1731 case FCmpInst::FCMP_ULE:
1732 // All values are unordered with and at most infinity.
1733 return ConstantInt::getTrue(CFP->getContext());
1742 // If the comparison is with the result of a select instruction, check whether
1743 // comparing with either branch of the select always yields the same value.
1744 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1745 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1748 // If the comparison is with the result of a phi instruction, check whether
1749 // doing the compare with each incoming phi value yields a common result.
1750 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1751 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1757 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1758 const TargetData *TD, const DominatorTree *DT) {
1759 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1762 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
1763 /// the result. If not, this returns null.
1764 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
1765 const TargetData *TD, const DominatorTree *) {
1766 // select true, X, Y -> X
1767 // select false, X, Y -> Y
1768 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
1769 return CB->getZExtValue() ? TrueVal : FalseVal;
1771 // select C, X, X -> X
1772 if (TrueVal == FalseVal)
1775 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
1777 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
1779 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
1780 if (isa<Constant>(TrueVal))
1788 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
1789 /// fold the result. If not, this returns null.
1790 Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
1791 const TargetData *TD, const DominatorTree *) {
1792 // The type of the GEP pointer operand.
1793 const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
1795 // getelementptr P -> P.
1799 if (isa<UndefValue>(Ops[0])) {
1800 // Compute the (pointer) type returned by the GEP instruction.
1801 const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
1803 const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
1804 return UndefValue::get(GEPTy);
1808 // getelementptr P, 0 -> P.
1809 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
1812 // getelementptr P, N -> P if P points to a type of zero size.
1814 const Type *Ty = PtrTy->getElementType();
1815 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
1820 // Check to see if this is constant foldable.
1821 for (unsigned i = 0; i != NumOps; ++i)
1822 if (!isa<Constant>(Ops[i]))
1825 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
1826 (Constant *const*)Ops+1, NumOps-1);
1829 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
1830 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
1831 // If all of the PHI's incoming values are the same then replace the PHI node
1832 // with the common value.
1833 Value *CommonValue = 0;
1834 bool HasUndefInput = false;
1835 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1836 Value *Incoming = PN->getIncomingValue(i);
1837 // If the incoming value is the phi node itself, it can safely be skipped.
1838 if (Incoming == PN) continue;
1839 if (isa<UndefValue>(Incoming)) {
1840 // Remember that we saw an undef value, but otherwise ignore them.
1841 HasUndefInput = true;
1844 if (CommonValue && Incoming != CommonValue)
1845 return 0; // Not the same, bail out.
1846 CommonValue = Incoming;
1849 // If CommonValue is null then all of the incoming values were either undef or
1850 // equal to the phi node itself.
1852 return UndefValue::get(PN->getType());
1854 // If we have a PHI node like phi(X, undef, X), where X is defined by some
1855 // instruction, we cannot return X as the result of the PHI node unless it
1856 // dominates the PHI block.
1858 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
1864 //=== Helper functions for higher up the class hierarchy.
1866 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
1867 /// fold the result. If not, this returns null.
1868 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1869 const TargetData *TD, const DominatorTree *DT,
1870 unsigned MaxRecurse) {
1872 case Instruction::Add:
1873 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
1874 TD, DT, MaxRecurse);
1875 case Instruction::Sub:
1876 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
1877 TD, DT, MaxRecurse);
1878 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, TD, DT, MaxRecurse);
1879 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, DT, MaxRecurse);
1880 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, DT, MaxRecurse);
1881 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, DT, MaxRecurse);
1882 case Instruction::Shl:
1883 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
1884 TD, DT, MaxRecurse);
1885 case Instruction::LShr:
1886 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, TD, DT, MaxRecurse);
1887 case Instruction::AShr:
1888 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, TD, DT, MaxRecurse);
1889 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
1890 case Instruction::Or: return SimplifyOrInst (LHS, RHS, TD, DT, MaxRecurse);
1891 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
1893 if (Constant *CLHS = dyn_cast<Constant>(LHS))
1894 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
1895 Constant *COps[] = {CLHS, CRHS};
1896 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
1899 // If the operation is associative, try some generic simplifications.
1900 if (Instruction::isAssociative(Opcode))
1901 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT,
1905 // If the operation is with the result of a select instruction, check whether
1906 // operating on either branch of the select always yields the same value.
1907 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1908 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
1912 // If the operation is with the result of a phi instruction, check whether
1913 // operating on all incoming values of the phi always yields the same value.
1914 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1915 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse))
1922 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1923 const TargetData *TD, const DominatorTree *DT) {
1924 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit);
1927 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
1928 /// fold the result.
1929 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1930 const TargetData *TD, const DominatorTree *DT,
1931 unsigned MaxRecurse) {
1932 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
1933 return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1934 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1937 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1938 const TargetData *TD, const DominatorTree *DT) {
1939 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1942 /// SimplifyInstruction - See if we can compute a simplified version of this
1943 /// instruction. If not, this returns null.
1944 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
1945 const DominatorTree *DT) {
1948 switch (I->getOpcode()) {
1950 Result = ConstantFoldInstruction(I, TD);
1952 case Instruction::Add:
1953 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
1954 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1955 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1958 case Instruction::Sub:
1959 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
1960 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1961 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1964 case Instruction::Mul:
1965 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
1967 case Instruction::SDiv:
1968 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
1970 case Instruction::UDiv:
1971 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
1973 case Instruction::FDiv:
1974 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
1976 case Instruction::Shl:
1977 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
1978 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1979 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1982 case Instruction::LShr:
1983 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
1984 cast<BinaryOperator>(I)->isExact(),
1987 case Instruction::AShr:
1988 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
1989 cast<BinaryOperator>(I)->isExact(),
1992 case Instruction::And:
1993 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
1995 case Instruction::Or:
1996 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1998 case Instruction::Xor:
1999 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
2001 case Instruction::ICmp:
2002 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
2003 I->getOperand(0), I->getOperand(1), TD, DT);
2005 case Instruction::FCmp:
2006 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
2007 I->getOperand(0), I->getOperand(1), TD, DT);
2009 case Instruction::Select:
2010 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
2011 I->getOperand(2), TD, DT);
2013 case Instruction::GetElementPtr: {
2014 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
2015 Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
2018 case Instruction::PHI:
2019 Result = SimplifyPHINode(cast<PHINode>(I), DT);
2023 /// If called on unreachable code, the above logic may report that the
2024 /// instruction simplified to itself. Make life easier for users by
2025 /// detecting that case here, returning a safe value instead.
2026 return Result == I ? UndefValue::get(I->getType()) : Result;
2029 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
2030 /// delete the From instruction. In addition to a basic RAUW, this does a
2031 /// recursive simplification of the newly formed instructions. This catches
2032 /// things where one simplification exposes other opportunities. This only
2033 /// simplifies and deletes scalar operations, it does not change the CFG.
2035 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
2036 const TargetData *TD,
2037 const DominatorTree *DT) {
2038 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
2040 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
2041 // we can know if it gets deleted out from under us or replaced in a
2042 // recursive simplification.
2043 WeakVH FromHandle(From);
2044 WeakVH ToHandle(To);
2046 while (!From->use_empty()) {
2047 // Update the instruction to use the new value.
2048 Use &TheUse = From->use_begin().getUse();
2049 Instruction *User = cast<Instruction>(TheUse.getUser());
2052 // Check to see if the instruction can be folded due to the operand
2053 // replacement. For example changing (or X, Y) into (or X, -1) can replace
2054 // the 'or' with -1.
2055 Value *SimplifiedVal;
2057 // Sanity check to make sure 'User' doesn't dangle across
2058 // SimplifyInstruction.
2059 AssertingVH<> UserHandle(User);
2061 SimplifiedVal = SimplifyInstruction(User, TD, DT);
2062 if (SimplifiedVal == 0) continue;
2065 // Recursively simplify this user to the new value.
2066 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT);
2067 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
2070 assert(ToHandle && "To value deleted by recursive simplification?");
2072 // If the recursive simplification ended up revisiting and deleting
2073 // 'From' then we're done.
2078 // If 'From' has value handles referring to it, do a real RAUW to update them.
2079 From->replaceAllUsesWith(To);
2081 From->eraseFromParent();