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 #define 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.
412 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
413 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
414 /// it on the incoming phi values yields the same result for every value. If so
415 /// returns the common value, otherwise returns null.
416 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
417 const TargetData *TD, const DominatorTree *DT,
418 unsigned MaxRecurse) {
419 // Recursion is always used, so bail out at once if we already hit the limit.
424 if (isa<PHINode>(LHS)) {
425 PI = cast<PHINode>(LHS);
426 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
427 if (!ValueDominatesPHI(RHS, PI, DT))
430 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
431 PI = cast<PHINode>(RHS);
432 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
433 if (!ValueDominatesPHI(LHS, PI, DT))
437 // Evaluate the BinOp on the incoming phi values.
438 Value *CommonValue = 0;
439 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
440 Value *Incoming = PI->getIncomingValue(i);
441 // If the incoming value is the phi node itself, it can safely be skipped.
442 if (Incoming == PI) continue;
443 Value *V = PI == LHS ?
444 SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) :
445 SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, MaxRecurse);
446 // If the operation failed to simplify, or simplified to a different value
447 // to previously, then give up.
448 if (!V || (CommonValue && V != CommonValue))
456 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
457 /// try to simplify the comparison by seeing whether comparing with all of the
458 /// incoming phi values yields the same result every time. If so returns the
459 /// common result, otherwise returns null.
460 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
461 const TargetData *TD, const DominatorTree *DT,
462 unsigned MaxRecurse) {
463 // Recursion is always used, so bail out at once if we already hit the limit.
467 // Make sure the phi is on the LHS.
468 if (!isa<PHINode>(LHS)) {
470 Pred = CmpInst::getSwappedPredicate(Pred);
472 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
473 PHINode *PI = cast<PHINode>(LHS);
475 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
476 if (!ValueDominatesPHI(RHS, PI, DT))
479 // Evaluate the BinOp on the incoming phi values.
480 Value *CommonValue = 0;
481 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
482 Value *Incoming = PI->getIncomingValue(i);
483 // If the incoming value is the phi node itself, it can safely be skipped.
484 if (Incoming == PI) continue;
485 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse);
486 // If the operation failed to simplify, or simplified to a different value
487 // to previously, then give up.
488 if (!V || (CommonValue && V != CommonValue))
496 /// SimplifyAddInst - Given operands for an Add, see if we can
497 /// fold the result. If not, this returns null.
498 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
499 const TargetData *TD, const DominatorTree *DT,
500 unsigned MaxRecurse) {
501 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
502 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
503 Constant *Ops[] = { CLHS, CRHS };
504 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
508 // Canonicalize the constant to the RHS.
512 // X + undef -> undef
513 if (match(Op1, m_Undef()))
517 if (match(Op1, m_Zero()))
524 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
525 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
528 // X + ~X -> -1 since ~X = -X-1
529 if (match(Op0, m_Not(m_Specific(Op1))) ||
530 match(Op1, m_Not(m_Specific(Op0))))
531 return Constant::getAllOnesValue(Op0->getType());
534 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
535 if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
538 // Try some generic simplifications for associative operations.
539 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT,
543 // Mul distributes over Add. Try some generic simplifications based on this.
544 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
548 // Threading Add over selects and phi nodes is pointless, so don't bother.
549 // Threading over the select in "A + select(cond, B, C)" means evaluating
550 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
551 // only if B and C are equal. If B and C are equal then (since we assume
552 // that operands have already been simplified) "select(cond, B, C)" should
553 // have been simplified to the common value of B and C already. Analysing
554 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
555 // for threading over phi nodes.
560 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
561 const TargetData *TD, const DominatorTree *DT) {
562 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
565 /// SimplifySubInst - Given operands for a Sub, see if we can
566 /// fold the result. If not, this returns null.
567 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
568 const TargetData *TD, const DominatorTree *DT,
569 unsigned MaxRecurse) {
570 if (Constant *CLHS = dyn_cast<Constant>(Op0))
571 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
572 Constant *Ops[] = { CLHS, CRHS };
573 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
577 // X - undef -> undef
578 // undef - X -> undef
579 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
580 return UndefValue::get(Op0->getType());
583 if (match(Op1, m_Zero()))
588 return Constant::getNullValue(Op0->getType());
593 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
594 match(Op0, m_Shl(m_Specific(Op1), m_One())))
597 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
598 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
599 Value *Y = 0, *Z = Op1;
600 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
601 // See if "V === Y - Z" simplifies.
602 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, DT, MaxRecurse-1))
603 // It does! Now see if "X + V" simplifies.
604 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, DT,
606 // It does, we successfully reassociated!
610 // See if "V === X - Z" simplifies.
611 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
612 // It does! Now see if "Y + V" simplifies.
613 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, DT,
615 // It does, we successfully reassociated!
621 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
622 // For example, X - (X + 1) -> -1
624 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
625 // See if "V === X - Y" simplifies.
626 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, DT, MaxRecurse-1))
627 // It does! Now see if "V - Z" simplifies.
628 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, DT,
630 // It does, we successfully reassociated!
634 // See if "V === X - Z" simplifies.
635 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
636 // It does! Now see if "V - Y" simplifies.
637 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, DT,
639 // It does, we successfully reassociated!
645 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
646 // For example, X - (X - Y) -> Y.
648 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
649 // See if "V === Z - X" simplifies.
650 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, DT, MaxRecurse-1))
651 // It does! Now see if "V + Y" simplifies.
652 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, DT,
654 // It does, we successfully reassociated!
659 // Mul distributes over Sub. Try some generic simplifications based on this.
660 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
665 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
666 if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
669 // Threading Sub over selects and phi nodes is pointless, so don't bother.
670 // Threading over the select in "A - select(cond, B, C)" means evaluating
671 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
672 // only if B and C are equal. If B and C are equal then (since we assume
673 // that operands have already been simplified) "select(cond, B, C)" should
674 // have been simplified to the common value of B and C already. Analysing
675 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
676 // for threading over phi nodes.
681 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
682 const TargetData *TD, const DominatorTree *DT) {
683 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
686 /// SimplifyMulInst - Given operands for a Mul, see if we can
687 /// fold the result. If not, this returns null.
688 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
689 const DominatorTree *DT, unsigned MaxRecurse) {
690 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
691 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
692 Constant *Ops[] = { CLHS, CRHS };
693 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
697 // Canonicalize the constant to the RHS.
702 if (match(Op1, m_Undef()))
703 return Constant::getNullValue(Op0->getType());
706 if (match(Op1, m_Zero()))
710 if (match(Op1, m_One()))
713 // (X / Y) * Y -> X if the division is exact.
714 Value *X = 0, *Y = 0;
715 if ((match(Op0, m_SDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y
716 (match(Op1, m_SDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y)
717 BinaryOperator *SDiv = cast<BinaryOperator>(Y == Op1 ? Op0 : Op1);
723 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
724 if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1))
727 // Try some generic simplifications for associative operations.
728 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
732 // Mul distributes over Add. Try some generic simplifications based on this.
733 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
737 // If the operation is with the result of a select instruction, check whether
738 // operating on either branch of the select always yields the same value.
739 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
740 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
744 // If the operation is with the result of a phi instruction, check whether
745 // operating on all incoming values of the phi always yields the same value.
746 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
747 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
754 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
755 const DominatorTree *DT) {
756 return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
759 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
760 /// fold the result. If not, this returns null.
761 static Value *SimplifyDiv(unsigned Opcode, Value *Op0, Value *Op1,
762 const TargetData *TD, const DominatorTree *DT,
763 unsigned MaxRecurse) {
764 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
765 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
766 Constant *Ops[] = { C0, C1 };
767 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
771 bool isSigned = Opcode == Instruction::SDiv;
773 // X / undef -> undef
774 if (match(Op1, m_Undef()))
778 if (match(Op0, m_Undef()))
779 return Constant::getNullValue(Op0->getType());
781 // 0 / X -> 0, we don't need to preserve faults!
782 if (match(Op0, m_Zero()))
786 if (match(Op1, m_One()))
789 if (Op0->getType()->isIntegerTy(1))
790 // It can't be division by zero, hence it must be division by one.
795 return ConstantInt::get(Op0->getType(), 1);
797 // (X * Y) / Y -> X if the multiplication does not overflow.
798 Value *X = 0, *Y = 0;
799 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
800 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
801 // BinaryOperator *Mul = cast<BinaryOperator>(Op0);
802 // // If the Mul knows it does not overflow, then we are good to go.
803 // if ((isSigned && Mul->hasNoSignedWrap()) ||
804 // (!isSigned && Mul->hasNoUnsignedWrap()))
806 // If X has the form X = A / Y then X * Y cannot overflow.
807 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
808 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
812 // (X rem Y) / Y -> 0
813 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
814 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
815 return Constant::getNullValue(Op0->getType());
817 // If the operation is with the result of a select instruction, check whether
818 // operating on either branch of the select always yields the same value.
819 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
820 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
823 // If the operation is with the result of a phi instruction, check whether
824 // operating on all incoming values of the phi always yields the same value.
825 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
826 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
832 /// SimplifySDivInst - Given operands for an SDiv, see if we can
833 /// fold the result. If not, this returns null.
834 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
835 const DominatorTree *DT, unsigned MaxRecurse) {
836 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, DT, MaxRecurse))
842 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
843 const DominatorTree *DT) {
844 return ::SimplifySDivInst(Op0, Op1, TD, DT, RecursionLimit);
847 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
848 /// fold the result. If not, this returns null.
849 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
850 const DominatorTree *DT, unsigned MaxRecurse) {
851 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, DT, MaxRecurse))
857 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
858 const DominatorTree *DT) {
859 return ::SimplifyUDivInst(Op0, Op1, TD, DT, RecursionLimit);
862 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *,
863 const DominatorTree *, unsigned) {
864 // undef / X -> undef (the undef could be a snan).
865 if (match(Op0, m_Undef()))
868 // X / undef -> undef
869 if (match(Op1, m_Undef()))
875 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
876 const DominatorTree *DT) {
877 return ::SimplifyFDivInst(Op0, Op1, TD, DT, RecursionLimit);
880 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
881 /// fold the result. If not, this returns null.
882 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
883 const TargetData *TD, const DominatorTree *DT,
884 unsigned MaxRecurse) {
885 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
886 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
887 Constant *Ops[] = { C0, C1 };
888 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
893 if (match(Op0, m_Zero()))
897 if (match(Op1, m_Zero()))
900 // X shift by undef -> undef because it may shift by the bitwidth.
901 if (match(Op1, m_Undef()))
904 // Shifting by the bitwidth or more is undefined.
905 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
906 if (CI->getValue().getLimitedValue() >=
907 Op0->getType()->getScalarSizeInBits())
908 return UndefValue::get(Op0->getType());
910 // If the operation is with the result of a select instruction, check whether
911 // operating on either branch of the select always yields the same value.
912 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
913 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
916 // If the operation is with the result of a phi instruction, check whether
917 // operating on all incoming values of the phi always yields the same value.
918 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
919 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
925 /// SimplifyShlInst - Given operands for an Shl, see if we can
926 /// fold the result. If not, this returns null.
927 static Value *SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD,
928 const DominatorTree *DT, unsigned MaxRecurse) {
929 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, DT, MaxRecurse))
933 if (match(Op0, m_Undef()))
934 return Constant::getNullValue(Op0->getType());
939 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD,
940 const DominatorTree *DT) {
941 return ::SimplifyShlInst(Op0, Op1, TD, DT, RecursionLimit);
944 /// SimplifyLShrInst - Given operands for an LShr, see if we can
945 /// fold the result. If not, this returns null.
946 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, const TargetData *TD,
947 const DominatorTree *DT, unsigned MaxRecurse) {
948 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, DT, MaxRecurse))
952 if (match(Op0, m_Undef()))
953 return Constant::getNullValue(Op0->getType());
958 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, const TargetData *TD,
959 const DominatorTree *DT) {
960 return ::SimplifyLShrInst(Op0, Op1, TD, DT, RecursionLimit);
963 /// SimplifyAShrInst - Given operands for an AShr, see if we can
964 /// fold the result. If not, this returns null.
965 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, const TargetData *TD,
966 const DominatorTree *DT, unsigned MaxRecurse) {
967 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, DT, MaxRecurse))
970 // all ones >>a X -> all ones
971 if (match(Op0, m_AllOnes()))
974 // undef >>a X -> all ones
975 if (match(Op0, m_Undef()))
976 return Constant::getAllOnesValue(Op0->getType());
981 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, const TargetData *TD,
982 const DominatorTree *DT) {
983 return ::SimplifyAShrInst(Op0, Op1, TD, DT, RecursionLimit);
986 /// SimplifyAndInst - Given operands for an And, see if we can
987 /// fold the result. If not, this returns null.
988 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
989 const DominatorTree *DT, unsigned MaxRecurse) {
990 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
991 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
992 Constant *Ops[] = { CLHS, CRHS };
993 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
997 // Canonicalize the constant to the RHS.
1002 if (match(Op1, m_Undef()))
1003 return Constant::getNullValue(Op0->getType());
1010 if (match(Op1, m_Zero()))
1014 if (match(Op1, m_AllOnes()))
1017 // A & ~A = ~A & A = 0
1018 Value *A = 0, *B = 0;
1019 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
1020 (match(Op1, m_Not(m_Value(A))) && A == Op0))
1021 return Constant::getNullValue(Op0->getType());
1024 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1025 (A == Op1 || B == Op1))
1029 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1030 (A == Op0 || B == Op0))
1033 // Try some generic simplifications for associative operations.
1034 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT,
1038 // And distributes over Or. Try some generic simplifications based on this.
1039 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1040 TD, DT, MaxRecurse))
1043 // And distributes over Xor. Try some generic simplifications based on this.
1044 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1045 TD, DT, MaxRecurse))
1048 // Or distributes over And. Try some generic simplifications based on this.
1049 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1050 TD, DT, MaxRecurse))
1053 // If the operation is with the result of a select instruction, check whether
1054 // operating on either branch of the select always yields the same value.
1055 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1056 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
1060 // If the operation is with the result of a phi instruction, check whether
1061 // operating on all incoming values of the phi always yields the same value.
1062 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1063 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
1070 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1071 const DominatorTree *DT) {
1072 return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit);
1075 /// SimplifyOrInst - Given operands for an Or, see if we can
1076 /// fold the result. If not, this returns null.
1077 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1078 const DominatorTree *DT, unsigned MaxRecurse) {
1079 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1080 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1081 Constant *Ops[] = { CLHS, CRHS };
1082 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1086 // Canonicalize the constant to the RHS.
1087 std::swap(Op0, Op1);
1091 if (match(Op1, m_Undef()))
1092 return Constant::getAllOnesValue(Op0->getType());
1099 if (match(Op1, m_Zero()))
1103 if (match(Op1, m_AllOnes()))
1106 // A | ~A = ~A | A = -1
1107 Value *A = 0, *B = 0;
1108 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
1109 (match(Op1, m_Not(m_Value(A))) && A == Op0))
1110 return Constant::getAllOnesValue(Op0->getType());
1113 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1114 (A == Op1 || B == Op1))
1118 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1119 (A == Op0 || B == Op0))
1122 // Try some generic simplifications for associative operations.
1123 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT,
1127 // Or distributes over And. Try some generic simplifications based on this.
1128 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1129 TD, DT, MaxRecurse))
1132 // And distributes over Or. Try some generic simplifications based on this.
1133 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1134 TD, DT, MaxRecurse))
1137 // If the operation is with the result of a select instruction, check whether
1138 // operating on either branch of the select always yields the same value.
1139 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1140 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
1144 // If the operation is with the result of a phi instruction, check whether
1145 // operating on all incoming values of the phi always yields the same value.
1146 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1147 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
1154 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1155 const DominatorTree *DT) {
1156 return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
1159 /// SimplifyXorInst - Given operands for a Xor, see if we can
1160 /// fold the result. If not, this returns null.
1161 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1162 const DominatorTree *DT, unsigned MaxRecurse) {
1163 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1164 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1165 Constant *Ops[] = { CLHS, CRHS };
1166 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1170 // Canonicalize the constant to the RHS.
1171 std::swap(Op0, Op1);
1174 // A ^ undef -> undef
1175 if (match(Op1, m_Undef()))
1179 if (match(Op1, m_Zero()))
1184 return Constant::getNullValue(Op0->getType());
1186 // A ^ ~A = ~A ^ A = -1
1188 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
1189 (match(Op1, m_Not(m_Value(A))) && A == Op0))
1190 return Constant::getAllOnesValue(Op0->getType());
1192 // Try some generic simplifications for associative operations.
1193 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT,
1197 // And distributes over Xor. Try some generic simplifications based on this.
1198 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1199 TD, DT, MaxRecurse))
1202 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1203 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1204 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1205 // only if B and C are equal. If B and C are equal then (since we assume
1206 // that operands have already been simplified) "select(cond, B, C)" should
1207 // have been simplified to the common value of B and C already. Analysing
1208 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1209 // for threading over phi nodes.
1214 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1215 const DominatorTree *DT) {
1216 return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
1219 static const Type *GetCompareTy(Value *Op) {
1220 return CmpInst::makeCmpResultType(Op->getType());
1223 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1224 /// fold the result. If not, this returns null.
1225 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1226 const TargetData *TD, const DominatorTree *DT,
1227 unsigned MaxRecurse) {
1228 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1229 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1231 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1232 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1233 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
1235 // If we have a constant, make sure it is on the RHS.
1236 std::swap(LHS, RHS);
1237 Pred = CmpInst::getSwappedPredicate(Pred);
1240 const Type *ITy = GetCompareTy(LHS); // The return type.
1241 const Type *OpTy = LHS->getType(); // The operand type.
1243 // icmp X, X -> true/false
1244 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1245 // because X could be 0.
1246 if (LHS == RHS || isa<UndefValue>(RHS))
1247 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1249 // Special case logic when the operands have i1 type.
1250 if (OpTy->isIntegerTy(1) || (OpTy->isVectorTy() &&
1251 cast<VectorType>(OpTy)->getElementType()->isIntegerTy(1))) {
1254 case ICmpInst::ICMP_EQ:
1256 if (match(RHS, m_One()))
1259 case ICmpInst::ICMP_NE:
1261 if (match(RHS, m_Zero()))
1264 case ICmpInst::ICMP_UGT:
1266 if (match(RHS, m_Zero()))
1269 case ICmpInst::ICMP_UGE:
1271 if (match(RHS, m_One()))
1274 case ICmpInst::ICMP_SLT:
1276 if (match(RHS, m_Zero()))
1279 case ICmpInst::ICMP_SLE:
1281 if (match(RHS, m_One()))
1287 // icmp <alloca*>, <global/alloca*/null> - Different stack variables have
1288 // different addresses, and what's more the address of a stack variable is
1289 // never null or equal to the address of a global. Note that generalizing
1290 // to the case where LHS is a global variable address or null is pointless,
1291 // since if both LHS and RHS are constants then we already constant folded
1292 // the compare, and if only one of them is then we moved it to RHS already.
1293 if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
1294 isa<ConstantPointerNull>(RHS)))
1295 // We already know that LHS != LHS.
1296 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
1298 // If we are comparing with zero then try hard since this is a common case.
1299 if (match(RHS, m_Zero())) {
1300 bool LHSKnownNonNegative, LHSKnownNegative;
1303 assert(false && "Unknown ICmp predicate!");
1304 case ICmpInst::ICMP_ULT:
1305 return ConstantInt::getFalse(LHS->getContext());
1306 case ICmpInst::ICMP_UGE:
1307 return ConstantInt::getTrue(LHS->getContext());
1308 case ICmpInst::ICMP_EQ:
1309 case ICmpInst::ICMP_ULE:
1310 if (isKnownNonZero(LHS, TD))
1311 return ConstantInt::getFalse(LHS->getContext());
1313 case ICmpInst::ICMP_NE:
1314 case ICmpInst::ICMP_UGT:
1315 if (isKnownNonZero(LHS, TD))
1316 return ConstantInt::getTrue(LHS->getContext());
1318 case ICmpInst::ICMP_SLT:
1319 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1320 if (LHSKnownNegative)
1321 return ConstantInt::getTrue(LHS->getContext());
1322 if (LHSKnownNonNegative)
1323 return ConstantInt::getFalse(LHS->getContext());
1325 case ICmpInst::ICMP_SLE:
1326 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1327 if (LHSKnownNegative)
1328 return ConstantInt::getTrue(LHS->getContext());
1329 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1330 return ConstantInt::getFalse(LHS->getContext());
1332 case ICmpInst::ICMP_SGE:
1333 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1334 if (LHSKnownNegative)
1335 return ConstantInt::getFalse(LHS->getContext());
1336 if (LHSKnownNonNegative)
1337 return ConstantInt::getTrue(LHS->getContext());
1339 case ICmpInst::ICMP_SGT:
1340 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1341 if (LHSKnownNegative)
1342 return ConstantInt::getFalse(LHS->getContext());
1343 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1344 return ConstantInt::getTrue(LHS->getContext());
1349 // See if we are doing a comparison with a constant integer.
1350 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1353 case ICmpInst::ICMP_UGT:
1354 if (CI->isMaxValue(false)) // A >u MAX -> FALSE
1355 return ConstantInt::getFalse(CI->getContext());
1357 case ICmpInst::ICMP_UGE:
1358 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
1359 return ConstantInt::getTrue(CI->getContext());
1361 case ICmpInst::ICMP_ULT:
1362 if (CI->isMinValue(false)) // A <u MIN -> FALSE
1363 return ConstantInt::getFalse(CI->getContext());
1365 case ICmpInst::ICMP_ULE:
1366 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
1367 return ConstantInt::getTrue(CI->getContext());
1369 case ICmpInst::ICMP_SGT:
1370 if (CI->isMaxValue(true)) // A >s MAX -> FALSE
1371 return ConstantInt::getFalse(CI->getContext());
1373 case ICmpInst::ICMP_SGE:
1374 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
1375 return ConstantInt::getTrue(CI->getContext());
1377 case ICmpInst::ICMP_SLT:
1378 if (CI->isMinValue(true)) // A <s MIN -> FALSE
1379 return ConstantInt::getFalse(CI->getContext());
1381 case ICmpInst::ICMP_SLE:
1382 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
1383 return ConstantInt::getTrue(CI->getContext());
1388 // Compare of cast, for example (zext X) != 0 -> X != 0
1389 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1390 Instruction *LI = cast<CastInst>(LHS);
1391 Value *SrcOp = LI->getOperand(0);
1392 const Type *SrcTy = SrcOp->getType();
1393 const Type *DstTy = LI->getType();
1395 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1396 // if the integer type is the same size as the pointer type.
1397 if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
1398 TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1399 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1400 // Transfer the cast to the constant.
1401 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1402 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1403 TD, DT, MaxRecurse-1))
1405 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1406 if (RI->getOperand(0)->getType() == SrcTy)
1407 // Compare without the cast.
1408 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1409 TD, DT, MaxRecurse-1))
1414 if (isa<ZExtInst>(LHS)) {
1415 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1417 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1418 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1419 // Compare X and Y. Note that signed predicates become unsigned.
1420 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1421 SrcOp, RI->getOperand(0), TD, DT,
1425 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1426 // too. If not, then try to deduce the result of the comparison.
1427 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1428 // Compute the constant that would happen if we truncated to SrcTy then
1429 // reextended to DstTy.
1430 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1431 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1433 // If the re-extended constant didn't change then this is effectively
1434 // also a case of comparing two zero-extended values.
1435 if (RExt == CI && MaxRecurse)
1436 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1437 SrcOp, Trunc, TD, DT, MaxRecurse-1))
1440 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1441 // there. Use this to work out the result of the comparison.
1445 assert(false && "Unknown ICmp predicate!");
1447 case ICmpInst::ICMP_EQ:
1448 case ICmpInst::ICMP_UGT:
1449 case ICmpInst::ICMP_UGE:
1450 return ConstantInt::getFalse(CI->getContext());
1452 case ICmpInst::ICMP_NE:
1453 case ICmpInst::ICMP_ULT:
1454 case ICmpInst::ICMP_ULE:
1455 return ConstantInt::getTrue(CI->getContext());
1457 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1458 // is non-negative then LHS <s RHS.
1459 case ICmpInst::ICMP_SGT:
1460 case ICmpInst::ICMP_SGE:
1461 return CI->getValue().isNegative() ?
1462 ConstantInt::getTrue(CI->getContext()) :
1463 ConstantInt::getFalse(CI->getContext());
1465 case ICmpInst::ICMP_SLT:
1466 case ICmpInst::ICMP_SLE:
1467 return CI->getValue().isNegative() ?
1468 ConstantInt::getFalse(CI->getContext()) :
1469 ConstantInt::getTrue(CI->getContext());
1475 if (isa<SExtInst>(LHS)) {
1476 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1478 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1479 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1480 // Compare X and Y. Note that the predicate does not change.
1481 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1482 TD, DT, MaxRecurse-1))
1485 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1486 // too. If not, then try to deduce the result of the comparison.
1487 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1488 // Compute the constant that would happen if we truncated to SrcTy then
1489 // reextended to DstTy.
1490 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1491 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1493 // If the re-extended constant didn't change then this is effectively
1494 // also a case of comparing two sign-extended values.
1495 if (RExt == CI && MaxRecurse)
1496 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, DT,
1500 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1501 // bits there. Use this to work out the result of the comparison.
1505 assert(false && "Unknown ICmp predicate!");
1506 case ICmpInst::ICMP_EQ:
1507 return ConstantInt::getFalse(CI->getContext());
1508 case ICmpInst::ICMP_NE:
1509 return ConstantInt::getTrue(CI->getContext());
1511 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1513 case ICmpInst::ICMP_SGT:
1514 case ICmpInst::ICMP_SGE:
1515 return CI->getValue().isNegative() ?
1516 ConstantInt::getTrue(CI->getContext()) :
1517 ConstantInt::getFalse(CI->getContext());
1518 case ICmpInst::ICMP_SLT:
1519 case ICmpInst::ICMP_SLE:
1520 return CI->getValue().isNegative() ?
1521 ConstantInt::getFalse(CI->getContext()) :
1522 ConstantInt::getTrue(CI->getContext());
1524 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
1526 case ICmpInst::ICMP_UGT:
1527 case ICmpInst::ICMP_UGE:
1528 // Comparison is true iff the LHS <s 0.
1530 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
1531 Constant::getNullValue(SrcTy),
1532 TD, DT, MaxRecurse-1))
1535 case ICmpInst::ICMP_ULT:
1536 case ICmpInst::ICMP_ULE:
1537 // Comparison is true iff the LHS >=s 0.
1539 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
1540 Constant::getNullValue(SrcTy),
1541 TD, DT, MaxRecurse-1))
1550 // If the comparison is with the result of a select instruction, check whether
1551 // comparing with either branch of the select always yields the same value.
1552 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1553 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1556 // If the comparison is with the result of a phi instruction, check whether
1557 // doing the compare with each incoming phi value yields a common result.
1558 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1559 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1565 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1566 const TargetData *TD, const DominatorTree *DT) {
1567 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1570 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
1571 /// fold the result. If not, this returns null.
1572 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1573 const TargetData *TD, const DominatorTree *DT,
1574 unsigned MaxRecurse) {
1575 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1576 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
1578 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1579 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1580 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
1582 // If we have a constant, make sure it is on the RHS.
1583 std::swap(LHS, RHS);
1584 Pred = CmpInst::getSwappedPredicate(Pred);
1587 // Fold trivial predicates.
1588 if (Pred == FCmpInst::FCMP_FALSE)
1589 return ConstantInt::get(GetCompareTy(LHS), 0);
1590 if (Pred == FCmpInst::FCMP_TRUE)
1591 return ConstantInt::get(GetCompareTy(LHS), 1);
1593 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
1594 return UndefValue::get(GetCompareTy(LHS));
1596 // fcmp x,x -> true/false. Not all compares are foldable.
1598 if (CmpInst::isTrueWhenEqual(Pred))
1599 return ConstantInt::get(GetCompareTy(LHS), 1);
1600 if (CmpInst::isFalseWhenEqual(Pred))
1601 return ConstantInt::get(GetCompareTy(LHS), 0);
1604 // Handle fcmp with constant RHS
1605 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1606 // If the constant is a nan, see if we can fold the comparison based on it.
1607 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1608 if (CFP->getValueAPF().isNaN()) {
1609 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
1610 return ConstantInt::getFalse(CFP->getContext());
1611 assert(FCmpInst::isUnordered(Pred) &&
1612 "Comparison must be either ordered or unordered!");
1613 // True if unordered.
1614 return ConstantInt::getTrue(CFP->getContext());
1616 // Check whether the constant is an infinity.
1617 if (CFP->getValueAPF().isInfinity()) {
1618 if (CFP->getValueAPF().isNegative()) {
1620 case FCmpInst::FCMP_OLT:
1621 // No value is ordered and less than negative infinity.
1622 return ConstantInt::getFalse(CFP->getContext());
1623 case FCmpInst::FCMP_UGE:
1624 // All values are unordered with or at least negative infinity.
1625 return ConstantInt::getTrue(CFP->getContext());
1631 case FCmpInst::FCMP_OGT:
1632 // No value is ordered and greater than infinity.
1633 return ConstantInt::getFalse(CFP->getContext());
1634 case FCmpInst::FCMP_ULE:
1635 // All values are unordered with and at most infinity.
1636 return ConstantInt::getTrue(CFP->getContext());
1645 // If the comparison is with the result of a select instruction, check whether
1646 // comparing with either branch of the select always yields the same value.
1647 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1648 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1651 // If the comparison is with the result of a phi instruction, check whether
1652 // doing the compare with each incoming phi value yields a common result.
1653 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1654 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1660 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1661 const TargetData *TD, const DominatorTree *DT) {
1662 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1665 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
1666 /// the result. If not, this returns null.
1667 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
1668 const TargetData *TD, const DominatorTree *) {
1669 // select true, X, Y -> X
1670 // select false, X, Y -> Y
1671 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
1672 return CB->getZExtValue() ? TrueVal : FalseVal;
1674 // select C, X, X -> X
1675 if (TrueVal == FalseVal)
1678 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
1680 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
1682 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
1683 if (isa<Constant>(TrueVal))
1691 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
1692 /// fold the result. If not, this returns null.
1693 Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
1694 const TargetData *TD, const DominatorTree *) {
1695 // The type of the GEP pointer operand.
1696 const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
1698 // getelementptr P -> P.
1702 if (isa<UndefValue>(Ops[0])) {
1703 // Compute the (pointer) type returned by the GEP instruction.
1704 const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
1706 const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
1707 return UndefValue::get(GEPTy);
1711 // getelementptr P, 0 -> P.
1712 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
1715 // getelementptr P, N -> P if P points to a type of zero size.
1717 const Type *Ty = PtrTy->getElementType();
1718 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
1723 // Check to see if this is constant foldable.
1724 for (unsigned i = 0; i != NumOps; ++i)
1725 if (!isa<Constant>(Ops[i]))
1728 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
1729 (Constant *const*)Ops+1, NumOps-1);
1732 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
1733 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
1734 // If all of the PHI's incoming values are the same then replace the PHI node
1735 // with the common value.
1736 Value *CommonValue = 0;
1737 bool HasUndefInput = false;
1738 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1739 Value *Incoming = PN->getIncomingValue(i);
1740 // If the incoming value is the phi node itself, it can safely be skipped.
1741 if (Incoming == PN) continue;
1742 if (isa<UndefValue>(Incoming)) {
1743 // Remember that we saw an undef value, but otherwise ignore them.
1744 HasUndefInput = true;
1747 if (CommonValue && Incoming != CommonValue)
1748 return 0; // Not the same, bail out.
1749 CommonValue = Incoming;
1752 // If CommonValue is null then all of the incoming values were either undef or
1753 // equal to the phi node itself.
1755 return UndefValue::get(PN->getType());
1757 // If we have a PHI node like phi(X, undef, X), where X is defined by some
1758 // instruction, we cannot return X as the result of the PHI node unless it
1759 // dominates the PHI block.
1761 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
1767 //=== Helper functions for higher up the class hierarchy.
1769 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
1770 /// fold the result. If not, this returns null.
1771 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1772 const TargetData *TD, const DominatorTree *DT,
1773 unsigned MaxRecurse) {
1775 case Instruction::Add: return SimplifyAddInst(LHS, RHS, /* isNSW */ false,
1776 /* isNUW */ false, TD, DT,
1778 case Instruction::Sub: return SimplifySubInst(LHS, RHS, /* isNSW */ false,
1779 /* isNUW */ false, TD, DT,
1781 case Instruction::Mul: return SimplifyMulInst(LHS, RHS, TD, DT, MaxRecurse);
1782 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, DT, MaxRecurse);
1783 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, DT, MaxRecurse);
1784 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, DT, MaxRecurse);
1785 case Instruction::Shl: return SimplifyShlInst(LHS, RHS, TD, DT, MaxRecurse);
1786 case Instruction::LShr: return SimplifyLShrInst(LHS, RHS, TD, DT, MaxRecurse);
1787 case Instruction::AShr: return SimplifyAShrInst(LHS, RHS, TD, DT, MaxRecurse);
1788 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
1789 case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
1790 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
1792 if (Constant *CLHS = dyn_cast<Constant>(LHS))
1793 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
1794 Constant *COps[] = {CLHS, CRHS};
1795 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
1798 // If the operation is associative, try some generic simplifications.
1799 if (Instruction::isAssociative(Opcode))
1800 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT,
1804 // If the operation is with the result of a select instruction, check whether
1805 // operating on either branch of the select always yields the same value.
1806 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1807 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
1811 // If the operation is with the result of a phi instruction, check whether
1812 // operating on all incoming values of the phi always yields the same value.
1813 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1814 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse))
1821 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1822 const TargetData *TD, const DominatorTree *DT) {
1823 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit);
1826 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
1827 /// fold the result.
1828 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1829 const TargetData *TD, const DominatorTree *DT,
1830 unsigned MaxRecurse) {
1831 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
1832 return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1833 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1836 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1837 const TargetData *TD, const DominatorTree *DT) {
1838 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1841 /// SimplifyInstruction - See if we can compute a simplified version of this
1842 /// instruction. If not, this returns null.
1843 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
1844 const DominatorTree *DT) {
1847 switch (I->getOpcode()) {
1849 Result = ConstantFoldInstruction(I, TD);
1851 case Instruction::Add:
1852 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
1853 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1854 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1857 case Instruction::Sub:
1858 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
1859 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1860 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1863 case Instruction::Mul:
1864 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
1866 case Instruction::SDiv:
1867 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
1869 case Instruction::UDiv:
1870 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
1872 case Instruction::FDiv:
1873 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
1875 case Instruction::Shl:
1876 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1), TD, DT);
1878 case Instruction::LShr:
1879 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1881 case Instruction::AShr:
1882 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1884 case Instruction::And:
1885 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
1887 case Instruction::Or:
1888 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1890 case Instruction::Xor:
1891 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
1893 case Instruction::ICmp:
1894 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
1895 I->getOperand(0), I->getOperand(1), TD, DT);
1897 case Instruction::FCmp:
1898 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
1899 I->getOperand(0), I->getOperand(1), TD, DT);
1901 case Instruction::Select:
1902 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
1903 I->getOperand(2), TD, DT);
1905 case Instruction::GetElementPtr: {
1906 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
1907 Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
1910 case Instruction::PHI:
1911 Result = SimplifyPHINode(cast<PHINode>(I), DT);
1915 /// If called on unreachable code, the above logic may report that the
1916 /// instruction simplified to itself. Make life easier for users by
1917 /// detecting that case here, returning a safe value instead.
1918 return Result == I ? UndefValue::get(I->getType()) : Result;
1921 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
1922 /// delete the From instruction. In addition to a basic RAUW, this does a
1923 /// recursive simplification of the newly formed instructions. This catches
1924 /// things where one simplification exposes other opportunities. This only
1925 /// simplifies and deletes scalar operations, it does not change the CFG.
1927 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
1928 const TargetData *TD,
1929 const DominatorTree *DT) {
1930 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
1932 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
1933 // we can know if it gets deleted out from under us or replaced in a
1934 // recursive simplification.
1935 WeakVH FromHandle(From);
1936 WeakVH ToHandle(To);
1938 while (!From->use_empty()) {
1939 // Update the instruction to use the new value.
1940 Use &TheUse = From->use_begin().getUse();
1941 Instruction *User = cast<Instruction>(TheUse.getUser());
1944 // Check to see if the instruction can be folded due to the operand
1945 // replacement. For example changing (or X, Y) into (or X, -1) can replace
1946 // the 'or' with -1.
1947 Value *SimplifiedVal;
1949 // Sanity check to make sure 'User' doesn't dangle across
1950 // SimplifyInstruction.
1951 AssertingVH<> UserHandle(User);
1953 SimplifiedVal = SimplifyInstruction(User, TD, DT);
1954 if (SimplifiedVal == 0) continue;
1957 // Recursively simplify this user to the new value.
1958 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT);
1959 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
1962 assert(ToHandle && "To value deleted by recursive simplification?");
1964 // If the recursive simplification ended up revisiting and deleting
1965 // 'From' then we're done.
1970 // If 'From' has value handles referring to it, do a real RAUW to update them.
1971 From->replaceAllUsesWith(To);
1973 From->eraseFromParent();