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 (isa<UndefValue>(Op1))
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 (isa<UndefValue>(Op0) || isa<UndefValue>(Op1))
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 (isa<UndefValue>(Op1))
703 return Constant::getNullValue(Op0->getType());
706 if (match(Op1, m_Zero()))
710 if (match(Op1, m_One()))
714 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
715 if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1))
718 // Try some generic simplifications for associative operations.
719 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
723 // Mul distributes over Add. Try some generic simplifications based on this.
724 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
728 // If the operation is with the result of a select instruction, check whether
729 // operating on either branch of the select always yields the same value.
730 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
731 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
735 // If the operation is with the result of a phi instruction, check whether
736 // operating on all incoming values of the phi always yields the same value.
737 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
738 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
745 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
746 const DominatorTree *DT) {
747 return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
750 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
751 /// fold the result. If not, this returns null.
752 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
753 const TargetData *TD, const DominatorTree *DT,
754 unsigned MaxRecurse) {
755 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
756 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
757 Constant *Ops[] = { C0, C1 };
758 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
763 if (match(Op0, m_Zero()))
767 if (match(Op1, m_Zero()))
770 // X shift by undef -> undef because it may shift by the bitwidth.
771 if (isa<UndefValue>(Op1))
774 // Shifting by the bitwidth or more is undefined.
775 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
776 if (CI->getValue().getLimitedValue() >=
777 Op0->getType()->getScalarSizeInBits())
778 return UndefValue::get(Op0->getType());
780 // If the operation is with the result of a select instruction, check whether
781 // operating on either branch of the select always yields the same value.
782 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
783 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
786 // If the operation is with the result of a phi instruction, check whether
787 // operating on all incoming values of the phi always yields the same value.
788 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
789 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
795 /// SimplifyShlInst - Given operands for an Shl, see if we can
796 /// fold the result. If not, this returns null.
797 static Value *SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD,
798 const DominatorTree *DT, unsigned MaxRecurse) {
799 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, DT, MaxRecurse))
803 if (isa<UndefValue>(Op0))
804 return Constant::getNullValue(Op0->getType());
809 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD,
810 const DominatorTree *DT) {
811 return ::SimplifyShlInst(Op0, Op1, TD, DT, RecursionLimit);
814 /// SimplifyLShrInst - Given operands for an LShr, see if we can
815 /// fold the result. If not, this returns null.
816 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, const TargetData *TD,
817 const DominatorTree *DT, unsigned MaxRecurse) {
818 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, DT, MaxRecurse))
822 if (isa<UndefValue>(Op0))
823 return Constant::getNullValue(Op0->getType());
828 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, const TargetData *TD,
829 const DominatorTree *DT) {
830 return ::SimplifyLShrInst(Op0, Op1, TD, DT, RecursionLimit);
833 /// SimplifyAShrInst - Given operands for an AShr, see if we can
834 /// fold the result. If not, this returns null.
835 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, const TargetData *TD,
836 const DominatorTree *DT, unsigned MaxRecurse) {
837 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, DT, MaxRecurse))
840 // all ones >>a X -> all ones
841 if (match(Op0, m_AllOnes()))
844 // undef >>a X -> all ones
845 if (isa<UndefValue>(Op0))
846 return Constant::getAllOnesValue(Op0->getType());
851 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, const TargetData *TD,
852 const DominatorTree *DT) {
853 return ::SimplifyAShrInst(Op0, Op1, TD, DT, RecursionLimit);
856 /// SimplifyAndInst - Given operands for an And, see if we can
857 /// fold the result. If not, this returns null.
858 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
859 const DominatorTree *DT, unsigned MaxRecurse) {
860 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
861 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
862 Constant *Ops[] = { CLHS, CRHS };
863 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
867 // Canonicalize the constant to the RHS.
872 if (isa<UndefValue>(Op1))
873 return Constant::getNullValue(Op0->getType());
880 if (match(Op1, m_Zero()))
884 if (match(Op1, m_AllOnes()))
887 // A & ~A = ~A & A = 0
888 Value *A = 0, *B = 0;
889 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
890 (match(Op1, m_Not(m_Value(A))) && A == Op0))
891 return Constant::getNullValue(Op0->getType());
894 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
895 (A == Op1 || B == Op1))
899 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
900 (A == Op0 || B == Op0))
903 // Try some generic simplifications for associative operations.
904 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT,
908 // And distributes over Or. Try some generic simplifications based on this.
909 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
913 // And distributes over Xor. Try some generic simplifications based on this.
914 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
918 // Or distributes over And. Try some generic simplifications based on this.
919 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
923 // If the operation is with the result of a select instruction, check whether
924 // operating on either branch of the select always yields the same value.
925 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
926 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
930 // If the operation is with the result of a phi instruction, check whether
931 // operating on all incoming values of the phi always yields the same value.
932 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
933 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
940 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
941 const DominatorTree *DT) {
942 return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit);
945 /// SimplifyOrInst - Given operands for an Or, see if we can
946 /// fold the result. If not, this returns null.
947 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
948 const DominatorTree *DT, unsigned MaxRecurse) {
949 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
950 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
951 Constant *Ops[] = { CLHS, CRHS };
952 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
956 // Canonicalize the constant to the RHS.
961 if (isa<UndefValue>(Op1))
962 return Constant::getAllOnesValue(Op0->getType());
969 if (match(Op1, m_Zero()))
973 if (match(Op1, m_AllOnes()))
976 // A | ~A = ~A | A = -1
977 Value *A = 0, *B = 0;
978 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
979 (match(Op1, m_Not(m_Value(A))) && A == Op0))
980 return Constant::getAllOnesValue(Op0->getType());
983 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
984 (A == Op1 || B == Op1))
988 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
989 (A == Op0 || B == Op0))
992 // Try some generic simplifications for associative operations.
993 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT,
997 // Or distributes over And. Try some generic simplifications based on this.
998 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1002 // And distributes over Or. Try some generic simplifications based on this.
1003 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1004 TD, DT, MaxRecurse))
1007 // If the operation is with the result of a select instruction, check whether
1008 // operating on either branch of the select always yields the same value.
1009 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1010 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
1014 // If the operation is with the result of a phi instruction, check whether
1015 // operating on all incoming values of the phi always yields the same value.
1016 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1017 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
1024 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1025 const DominatorTree *DT) {
1026 return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
1029 /// SimplifyXorInst - Given operands for a Xor, see if we can
1030 /// fold the result. If not, this returns null.
1031 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1032 const DominatorTree *DT, unsigned MaxRecurse) {
1033 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1034 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1035 Constant *Ops[] = { CLHS, CRHS };
1036 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1040 // Canonicalize the constant to the RHS.
1041 std::swap(Op0, Op1);
1044 // A ^ undef -> undef
1045 if (isa<UndefValue>(Op1))
1049 if (match(Op1, m_Zero()))
1054 return Constant::getNullValue(Op0->getType());
1056 // A ^ ~A = ~A ^ A = -1
1058 if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
1059 (match(Op1, m_Not(m_Value(A))) && A == Op0))
1060 return Constant::getAllOnesValue(Op0->getType());
1062 // Try some generic simplifications for associative operations.
1063 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT,
1067 // And distributes over Xor. Try some generic simplifications based on this.
1068 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1069 TD, DT, MaxRecurse))
1072 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1073 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1074 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1075 // only if B and C are equal. If B and C are equal then (since we assume
1076 // that operands have already been simplified) "select(cond, B, C)" should
1077 // have been simplified to the common value of B and C already. Analysing
1078 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1079 // for threading over phi nodes.
1084 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1085 const DominatorTree *DT) {
1086 return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
1089 static const Type *GetCompareTy(Value *Op) {
1090 return CmpInst::makeCmpResultType(Op->getType());
1093 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1094 /// fold the result. If not, this returns null.
1095 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1096 const TargetData *TD, const DominatorTree *DT,
1097 unsigned MaxRecurse) {
1098 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1099 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1101 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1102 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1103 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
1105 // If we have a constant, make sure it is on the RHS.
1106 std::swap(LHS, RHS);
1107 Pred = CmpInst::getSwappedPredicate(Pred);
1110 const Type *ITy = GetCompareTy(LHS); // The return type.
1111 const Type *OpTy = LHS->getType(); // The operand type.
1113 // icmp X, X -> true/false
1114 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1115 // because X could be 0.
1116 if (LHS == RHS || isa<UndefValue>(RHS))
1117 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1119 // Special case logic when the operands have i1 type.
1120 if (OpTy->isIntegerTy(1) || (OpTy->isVectorTy() &&
1121 cast<VectorType>(OpTy)->getElementType()->isIntegerTy(1))) {
1124 case ICmpInst::ICMP_EQ:
1126 if (match(RHS, m_One()))
1129 case ICmpInst::ICMP_NE:
1131 if (match(RHS, m_Zero()))
1134 case ICmpInst::ICMP_UGT:
1136 if (match(RHS, m_Zero()))
1139 case ICmpInst::ICMP_UGE:
1141 if (match(RHS, m_One()))
1144 case ICmpInst::ICMP_SLT:
1146 if (match(RHS, m_Zero()))
1149 case ICmpInst::ICMP_SLE:
1151 if (match(RHS, m_One()))
1157 // icmp <alloca*>, <global/alloca*/null> - Different stack variables have
1158 // different addresses, and what's more the address of a stack variable is
1159 // never null or equal to the address of a global. Note that generalizing
1160 // to the case where LHS is a global variable address or null is pointless,
1161 // since if both LHS and RHS are constants then we already constant folded
1162 // the compare, and if only one of them is then we moved it to RHS already.
1163 if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
1164 isa<ConstantPointerNull>(RHS)))
1165 // We already know that LHS != LHS.
1166 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
1168 // If we are comparing with zero then try hard since this is a common case.
1169 if (match(RHS, m_Zero())) {
1170 bool LHSKnownNonNegative, LHSKnownNegative;
1173 assert(false && "Unknown ICmp predicate!");
1174 case ICmpInst::ICMP_ULT:
1175 return ConstantInt::getFalse(LHS->getContext());
1176 case ICmpInst::ICMP_UGE:
1177 return ConstantInt::getTrue(LHS->getContext());
1178 case ICmpInst::ICMP_EQ:
1179 case ICmpInst::ICMP_ULE:
1180 if (isKnownNonZero(LHS, TD))
1181 return ConstantInt::getFalse(LHS->getContext());
1183 case ICmpInst::ICMP_NE:
1184 case ICmpInst::ICMP_UGT:
1185 if (isKnownNonZero(LHS, TD))
1186 return ConstantInt::getTrue(LHS->getContext());
1188 case ICmpInst::ICMP_SLT:
1189 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1190 if (LHSKnownNegative)
1191 return ConstantInt::getTrue(LHS->getContext());
1192 if (LHSKnownNonNegative)
1193 return ConstantInt::getFalse(LHS->getContext());
1195 case ICmpInst::ICMP_SLE:
1196 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1197 if (LHSKnownNegative)
1198 return ConstantInt::getTrue(LHS->getContext());
1199 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1200 return ConstantInt::getFalse(LHS->getContext());
1202 case ICmpInst::ICMP_SGE:
1203 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1204 if (LHSKnownNegative)
1205 return ConstantInt::getFalse(LHS->getContext());
1206 if (LHSKnownNonNegative)
1207 return ConstantInt::getTrue(LHS->getContext());
1209 case ICmpInst::ICMP_SGT:
1210 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
1211 if (LHSKnownNegative)
1212 return ConstantInt::getFalse(LHS->getContext());
1213 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
1214 return ConstantInt::getTrue(LHS->getContext());
1219 // See if we are doing a comparison with a constant integer.
1220 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1223 case ICmpInst::ICMP_UGT:
1224 if (CI->isMaxValue(false)) // A >u MAX -> FALSE
1225 return ConstantInt::getFalse(CI->getContext());
1227 case ICmpInst::ICMP_UGE:
1228 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
1229 return ConstantInt::getTrue(CI->getContext());
1231 case ICmpInst::ICMP_ULT:
1232 if (CI->isMinValue(false)) // A <u MIN -> FALSE
1233 return ConstantInt::getFalse(CI->getContext());
1235 case ICmpInst::ICMP_ULE:
1236 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
1237 return ConstantInt::getTrue(CI->getContext());
1239 case ICmpInst::ICMP_SGT:
1240 if (CI->isMaxValue(true)) // A >s MAX -> FALSE
1241 return ConstantInt::getFalse(CI->getContext());
1243 case ICmpInst::ICMP_SGE:
1244 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
1245 return ConstantInt::getTrue(CI->getContext());
1247 case ICmpInst::ICMP_SLT:
1248 if (CI->isMinValue(true)) // A <s MIN -> FALSE
1249 return ConstantInt::getFalse(CI->getContext());
1251 case ICmpInst::ICMP_SLE:
1252 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
1253 return ConstantInt::getTrue(CI->getContext());
1258 // Compare of cast, for example (zext X) != 0 -> X != 0
1259 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1260 Instruction *LI = cast<CastInst>(LHS);
1261 Value *SrcOp = LI->getOperand(0);
1262 const Type *SrcTy = SrcOp->getType();
1263 const Type *DstTy = LI->getType();
1265 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1266 // if the integer type is the same size as the pointer type.
1267 if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
1268 TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1269 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1270 // Transfer the cast to the constant.
1271 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1272 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1273 TD, DT, MaxRecurse-1))
1275 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1276 if (RI->getOperand(0)->getType() == SrcTy)
1277 // Compare without the cast.
1278 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1279 TD, DT, MaxRecurse-1))
1284 if (isa<ZExtInst>(LHS)) {
1285 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1287 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1288 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1289 // Compare X and Y. Note that signed predicates become unsigned.
1290 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1291 SrcOp, RI->getOperand(0), TD, DT,
1295 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1296 // too. If not, then try to deduce the result of the comparison.
1297 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1298 // Compute the constant that would happen if we truncated to SrcTy then
1299 // reextended to DstTy.
1300 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1301 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1303 // If the re-extended constant didn't change then this is effectively
1304 // also a case of comparing two zero-extended values.
1305 if (RExt == CI && MaxRecurse)
1306 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1307 SrcOp, Trunc, TD, DT, MaxRecurse-1))
1310 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1311 // there. Use this to work out the result of the comparison.
1315 assert(false && "Unknown ICmp predicate!");
1317 case ICmpInst::ICMP_EQ:
1318 case ICmpInst::ICMP_UGT:
1319 case ICmpInst::ICMP_UGE:
1320 return ConstantInt::getFalse(CI->getContext());
1322 case ICmpInst::ICMP_NE:
1323 case ICmpInst::ICMP_ULT:
1324 case ICmpInst::ICMP_ULE:
1325 return ConstantInt::getTrue(CI->getContext());
1327 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1328 // is non-negative then LHS <s RHS.
1329 case ICmpInst::ICMP_SGT:
1330 case ICmpInst::ICMP_SGE:
1331 return CI->getValue().isNegative() ?
1332 ConstantInt::getTrue(CI->getContext()) :
1333 ConstantInt::getFalse(CI->getContext());
1335 case ICmpInst::ICMP_SLT:
1336 case ICmpInst::ICMP_SLE:
1337 return CI->getValue().isNegative() ?
1338 ConstantInt::getFalse(CI->getContext()) :
1339 ConstantInt::getTrue(CI->getContext());
1345 if (isa<SExtInst>(LHS)) {
1346 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1348 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1349 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1350 // Compare X and Y. Note that the predicate does not change.
1351 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1352 TD, DT, MaxRecurse-1))
1355 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1356 // too. If not, then try to deduce the result of the comparison.
1357 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1358 // Compute the constant that would happen if we truncated to SrcTy then
1359 // reextended to DstTy.
1360 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1361 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1363 // If the re-extended constant didn't change then this is effectively
1364 // also a case of comparing two sign-extended values.
1365 if (RExt == CI && MaxRecurse)
1366 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, DT,
1370 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1371 // bits there. Use this to work out the result of the comparison.
1375 assert(false && "Unknown ICmp predicate!");
1376 case ICmpInst::ICMP_EQ:
1377 return ConstantInt::getFalse(CI->getContext());
1378 case ICmpInst::ICMP_NE:
1379 return ConstantInt::getTrue(CI->getContext());
1381 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1383 case ICmpInst::ICMP_SGT:
1384 case ICmpInst::ICMP_SGE:
1385 return CI->getValue().isNegative() ?
1386 ConstantInt::getTrue(CI->getContext()) :
1387 ConstantInt::getFalse(CI->getContext());
1388 case ICmpInst::ICMP_SLT:
1389 case ICmpInst::ICMP_SLE:
1390 return CI->getValue().isNegative() ?
1391 ConstantInt::getFalse(CI->getContext()) :
1392 ConstantInt::getTrue(CI->getContext());
1394 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
1396 case ICmpInst::ICMP_UGT:
1397 case ICmpInst::ICMP_UGE:
1398 // Comparison is true iff the LHS <s 0.
1400 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
1401 Constant::getNullValue(SrcTy),
1402 TD, DT, MaxRecurse-1))
1405 case ICmpInst::ICMP_ULT:
1406 case ICmpInst::ICMP_ULE:
1407 // Comparison is true iff the LHS >=s 0.
1409 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
1410 Constant::getNullValue(SrcTy),
1411 TD, DT, MaxRecurse-1))
1420 // If the comparison is with the result of a select instruction, check whether
1421 // comparing with either branch of the select always yields the same value.
1422 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1423 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1426 // If the comparison is with the result of a phi instruction, check whether
1427 // doing the compare with each incoming phi value yields a common result.
1428 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1429 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1435 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1436 const TargetData *TD, const DominatorTree *DT) {
1437 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1440 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
1441 /// fold the result. If not, this returns null.
1442 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1443 const TargetData *TD, const DominatorTree *DT,
1444 unsigned MaxRecurse) {
1445 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1446 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
1448 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1449 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1450 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
1452 // If we have a constant, make sure it is on the RHS.
1453 std::swap(LHS, RHS);
1454 Pred = CmpInst::getSwappedPredicate(Pred);
1457 // Fold trivial predicates.
1458 if (Pred == FCmpInst::FCMP_FALSE)
1459 return ConstantInt::get(GetCompareTy(LHS), 0);
1460 if (Pred == FCmpInst::FCMP_TRUE)
1461 return ConstantInt::get(GetCompareTy(LHS), 1);
1463 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
1464 return UndefValue::get(GetCompareTy(LHS));
1466 // fcmp x,x -> true/false. Not all compares are foldable.
1468 if (CmpInst::isTrueWhenEqual(Pred))
1469 return ConstantInt::get(GetCompareTy(LHS), 1);
1470 if (CmpInst::isFalseWhenEqual(Pred))
1471 return ConstantInt::get(GetCompareTy(LHS), 0);
1474 // Handle fcmp with constant RHS
1475 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1476 // If the constant is a nan, see if we can fold the comparison based on it.
1477 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
1478 if (CFP->getValueAPF().isNaN()) {
1479 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
1480 return ConstantInt::getFalse(CFP->getContext());
1481 assert(FCmpInst::isUnordered(Pred) &&
1482 "Comparison must be either ordered or unordered!");
1483 // True if unordered.
1484 return ConstantInt::getTrue(CFP->getContext());
1486 // Check whether the constant is an infinity.
1487 if (CFP->getValueAPF().isInfinity()) {
1488 if (CFP->getValueAPF().isNegative()) {
1490 case FCmpInst::FCMP_OLT:
1491 // No value is ordered and less than negative infinity.
1492 return ConstantInt::getFalse(CFP->getContext());
1493 case FCmpInst::FCMP_UGE:
1494 // All values are unordered with or at least negative infinity.
1495 return ConstantInt::getTrue(CFP->getContext());
1501 case FCmpInst::FCMP_OGT:
1502 // No value is ordered and greater than infinity.
1503 return ConstantInt::getFalse(CFP->getContext());
1504 case FCmpInst::FCMP_ULE:
1505 // All values are unordered with and at most infinity.
1506 return ConstantInt::getTrue(CFP->getContext());
1515 // If the comparison is with the result of a select instruction, check whether
1516 // comparing with either branch of the select always yields the same value.
1517 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1518 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
1521 // If the comparison is with the result of a phi instruction, check whether
1522 // doing the compare with each incoming phi value yields a common result.
1523 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1524 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
1530 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1531 const TargetData *TD, const DominatorTree *DT) {
1532 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1535 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
1536 /// the result. If not, this returns null.
1537 Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
1538 const TargetData *TD, const DominatorTree *) {
1539 // select true, X, Y -> X
1540 // select false, X, Y -> Y
1541 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
1542 return CB->getZExtValue() ? TrueVal : FalseVal;
1544 // select C, X, X -> X
1545 if (TrueVal == FalseVal)
1548 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
1550 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
1552 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
1553 if (isa<Constant>(TrueVal))
1561 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
1562 /// fold the result. If not, this returns null.
1563 Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
1564 const TargetData *TD, const DominatorTree *) {
1565 // The type of the GEP pointer operand.
1566 const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
1568 // getelementptr P -> P.
1572 if (isa<UndefValue>(Ops[0])) {
1573 // Compute the (pointer) type returned by the GEP instruction.
1574 const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
1576 const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
1577 return UndefValue::get(GEPTy);
1581 // getelementptr P, 0 -> P.
1582 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
1585 // getelementptr P, N -> P if P points to a type of zero size.
1587 const Type *Ty = PtrTy->getElementType();
1588 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
1593 // Check to see if this is constant foldable.
1594 for (unsigned i = 0; i != NumOps; ++i)
1595 if (!isa<Constant>(Ops[i]))
1598 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
1599 (Constant *const*)Ops+1, NumOps-1);
1602 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
1603 static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
1604 // If all of the PHI's incoming values are the same then replace the PHI node
1605 // with the common value.
1606 Value *CommonValue = 0;
1607 bool HasUndefInput = false;
1608 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1609 Value *Incoming = PN->getIncomingValue(i);
1610 // If the incoming value is the phi node itself, it can safely be skipped.
1611 if (Incoming == PN) continue;
1612 if (isa<UndefValue>(Incoming)) {
1613 // Remember that we saw an undef value, but otherwise ignore them.
1614 HasUndefInput = true;
1617 if (CommonValue && Incoming != CommonValue)
1618 return 0; // Not the same, bail out.
1619 CommonValue = Incoming;
1622 // If CommonValue is null then all of the incoming values were either undef or
1623 // equal to the phi node itself.
1625 return UndefValue::get(PN->getType());
1627 // If we have a PHI node like phi(X, undef, X), where X is defined by some
1628 // instruction, we cannot return X as the result of the PHI node unless it
1629 // dominates the PHI block.
1631 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
1637 //=== Helper functions for higher up the class hierarchy.
1639 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
1640 /// fold the result. If not, this returns null.
1641 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1642 const TargetData *TD, const DominatorTree *DT,
1643 unsigned MaxRecurse) {
1645 case Instruction::Add: return SimplifyAddInst(LHS, RHS, /* isNSW */ false,
1646 /* isNUW */ false, TD, DT,
1648 case Instruction::Sub: return SimplifySubInst(LHS, RHS, /* isNSW */ false,
1649 /* isNUW */ false, TD, DT,
1651 case Instruction::Mul: return SimplifyMulInst(LHS, RHS, TD, DT, MaxRecurse);
1652 case Instruction::Shl: return SimplifyShlInst(LHS, RHS, TD, DT, MaxRecurse);
1653 case Instruction::LShr: return SimplifyLShrInst(LHS, RHS, TD, DT, MaxRecurse);
1654 case Instruction::AShr: return SimplifyAShrInst(LHS, RHS, TD, DT, MaxRecurse);
1655 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
1656 case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
1657 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
1659 if (Constant *CLHS = dyn_cast<Constant>(LHS))
1660 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
1661 Constant *COps[] = {CLHS, CRHS};
1662 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
1665 // If the operation is associative, try some generic simplifications.
1666 if (Instruction::isAssociative(Opcode))
1667 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT,
1671 // If the operation is with the result of a select instruction, check whether
1672 // operating on either branch of the select always yields the same value.
1673 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
1674 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
1678 // If the operation is with the result of a phi instruction, check whether
1679 // operating on all incoming values of the phi always yields the same value.
1680 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
1681 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse))
1688 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
1689 const TargetData *TD, const DominatorTree *DT) {
1690 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit);
1693 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
1694 /// fold the result.
1695 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1696 const TargetData *TD, const DominatorTree *DT,
1697 unsigned MaxRecurse) {
1698 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
1699 return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1700 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
1703 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1704 const TargetData *TD, const DominatorTree *DT) {
1705 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
1708 /// SimplifyInstruction - See if we can compute a simplified version of this
1709 /// instruction. If not, this returns null.
1710 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
1711 const DominatorTree *DT) {
1714 switch (I->getOpcode()) {
1716 Result = ConstantFoldInstruction(I, TD);
1718 case Instruction::Add:
1719 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
1720 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1721 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1724 case Instruction::Sub:
1725 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
1726 cast<BinaryOperator>(I)->hasNoSignedWrap(),
1727 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
1730 case Instruction::Mul:
1731 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
1733 case Instruction::Shl:
1734 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1), TD, DT);
1736 case Instruction::LShr:
1737 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1739 case Instruction::AShr:
1740 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1742 case Instruction::And:
1743 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
1745 case Instruction::Or:
1746 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
1748 case Instruction::Xor:
1749 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
1751 case Instruction::ICmp:
1752 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
1753 I->getOperand(0), I->getOperand(1), TD, DT);
1755 case Instruction::FCmp:
1756 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
1757 I->getOperand(0), I->getOperand(1), TD, DT);
1759 case Instruction::Select:
1760 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
1761 I->getOperand(2), TD, DT);
1763 case Instruction::GetElementPtr: {
1764 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
1765 Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
1768 case Instruction::PHI:
1769 Result = SimplifyPHINode(cast<PHINode>(I), DT);
1773 /// If called on unreachable code, the above logic may report that the
1774 /// instruction simplified to itself. Make life easier for users by
1775 /// detecting that case here, returning a safe value instead.
1776 return Result == I ? UndefValue::get(I->getType()) : Result;
1779 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
1780 /// delete the From instruction. In addition to a basic RAUW, this does a
1781 /// recursive simplification of the newly formed instructions. This catches
1782 /// things where one simplification exposes other opportunities. This only
1783 /// simplifies and deletes scalar operations, it does not change the CFG.
1785 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
1786 const TargetData *TD,
1787 const DominatorTree *DT) {
1788 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
1790 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
1791 // we can know if it gets deleted out from under us or replaced in a
1792 // recursive simplification.
1793 WeakVH FromHandle(From);
1794 WeakVH ToHandle(To);
1796 while (!From->use_empty()) {
1797 // Update the instruction to use the new value.
1798 Use &TheUse = From->use_begin().getUse();
1799 Instruction *User = cast<Instruction>(TheUse.getUser());
1802 // Check to see if the instruction can be folded due to the operand
1803 // replacement. For example changing (or X, Y) into (or X, -1) can replace
1804 // the 'or' with -1.
1805 Value *SimplifiedVal;
1807 // Sanity check to make sure 'User' doesn't dangle across
1808 // SimplifyInstruction.
1809 AssertingVH<> UserHandle(User);
1811 SimplifiedVal = SimplifyInstruction(User, TD, DT);
1812 if (SimplifiedVal == 0) continue;
1815 // Recursively simplify this user to the new value.
1816 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT);
1817 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
1820 assert(ToHandle && "To value deleted by recursive simplification?");
1822 // If the recursive simplification ended up revisiting and deleting
1823 // 'From' then we're done.
1828 // If 'From' has value handles referring to it, do a real RAUW to update them.
1829 From->replaceAllUsesWith(To);
1831 From->eraseFromParent();