1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
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).
17 //
18 //===----------------------------------------------------------------------===//
19
20 #include "llvm/Analysis/InstructionSimplify.h"
21 #include "llvm/ADT/SetVector.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/Analysis/AliasAnalysis.h"
24 #include "llvm/Analysis/ConstantFolding.h"
25 #include "llvm/Analysis/MemoryBuiltins.h"
26 #include "llvm/Analysis/ValueTracking.h"
27 #include "llvm/IR/ConstantRange.h"
28 #include "llvm/IR/DataLayout.h"
29 #include "llvm/IR/Dominators.h"
30 #include "llvm/IR/GetElementPtrTypeIterator.h"
31 #include "llvm/IR/GlobalAlias.h"
32 #include "llvm/IR/Operator.h"
33 #include "llvm/IR/PatternMatch.h"
34 #include "llvm/IR/ValueHandle.h"
35 #include <algorithm>
36 using namespace llvm;
37 using namespace llvm::PatternMatch;
38
39 #define DEBUG_TYPE "instsimplify"
40
41 enum { RecursionLimit = 3 };
42
43 STATISTIC(NumExpand, "Number of expansions");
44 STATISTIC(NumReassoc, "Number of reassociations");
45
46 namespace {
47 struct Query {
48 const DataLayout *DL;
49 const TargetLibraryInfo *TLI;
50 const DominatorTree *DT;
51 AssumptionCache *AC;
52 const Instruction *CxtI;
53
Query__anon7f5e959d0211::Query54 Query(const DataLayout *DL, const TargetLibraryInfo *tli,
55 const DominatorTree *dt, AssumptionCache *ac = nullptr,
56 const Instruction *cxti = nullptr)
57 : DL(DL), TLI(tli), DT(dt), AC(ac), CxtI(cxti) {}
58 };
59 } // end anonymous namespace
60
61 static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
62 static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
63 unsigned);
64 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
65 unsigned);
66 static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
67 static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
68 static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned);
69
70 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
71 /// a vector with every element false, as appropriate for the type.
getFalse(Type * Ty)72 static Constant *getFalse(Type *Ty) {
73 assert(Ty->getScalarType()->isIntegerTy(1) &&
74 "Expected i1 type or a vector of i1!");
75 return Constant::getNullValue(Ty);
76 }
77
78 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
79 /// a vector with every element true, as appropriate for the type.
getTrue(Type * Ty)80 static Constant *getTrue(Type *Ty) {
81 assert(Ty->getScalarType()->isIntegerTy(1) &&
82 "Expected i1 type or a vector of i1!");
83 return Constant::getAllOnesValue(Ty);
84 }
85
86 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
isSameCompare(Value * V,CmpInst::Predicate Pred,Value * LHS,Value * RHS)87 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
88 Value *RHS) {
89 CmpInst *Cmp = dyn_cast<CmpInst>(V);
90 if (!Cmp)
91 return false;
92 CmpInst::Predicate CPred = Cmp->getPredicate();
93 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
94 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
95 return true;
96 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
97 CRHS == LHS;
98 }
99
100 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
ValueDominatesPHI(Value * V,PHINode * P,const DominatorTree * DT)101 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
102 Instruction *I = dyn_cast<Instruction>(V);
103 if (!I)
104 // Arguments and constants dominate all instructions.
105 return true;
106
107 // If we are processing instructions (and/or basic blocks) that have not been
108 // fully added to a function, the parent nodes may still be null. Simply
109 // return the conservative answer in these cases.
110 if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
111 return false;
112
113 // If we have a DominatorTree then do a precise test.
114 if (DT) {
115 if (!DT->isReachableFromEntry(P->getParent()))
116 return true;
117 if (!DT->isReachableFromEntry(I->getParent()))
118 return false;
119 return DT->dominates(I, P);
120 }
121
122 // Otherwise, if the instruction is in the entry block, and is not an invoke,
123 // then it obviously dominates all phi nodes.
124 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
125 !isa<InvokeInst>(I))
126 return true;
127
128 return false;
129 }
130
131 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
132 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
133 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
134 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
135 /// Returns the simplified value, or null if no simplification was performed.
ExpandBinOp(unsigned Opcode,Value * LHS,Value * RHS,unsigned OpcToExpand,const Query & Q,unsigned MaxRecurse)136 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
137 unsigned OpcToExpand, const Query &Q,
138 unsigned MaxRecurse) {
139 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
140 // Recursion is always used, so bail out at once if we already hit the limit.
141 if (!MaxRecurse--)
142 return nullptr;
143
144 // Check whether the expression has the form "(A op' B) op C".
145 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
146 if (Op0->getOpcode() == OpcodeToExpand) {
147 // It does! Try turning it into "(A op C) op' (B op C)".
148 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
149 // Do "A op C" and "B op C" both simplify?
150 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
151 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
152 // They do! Return "L op' R" if it simplifies or is already available.
153 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
154 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
155 && L == B && R == A)) {
156 ++NumExpand;
157 return LHS;
158 }
159 // Otherwise return "L op' R" if it simplifies.
160 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
161 ++NumExpand;
162 return V;
163 }
164 }
165 }
166
167 // Check whether the expression has the form "A op (B op' C)".
168 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
169 if (Op1->getOpcode() == OpcodeToExpand) {
170 // It does! Try turning it into "(A op B) op' (A op C)".
171 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
172 // Do "A op B" and "A op C" both simplify?
173 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
174 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
175 // They do! Return "L op' R" if it simplifies or is already available.
176 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
177 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
178 && L == C && R == B)) {
179 ++NumExpand;
180 return RHS;
181 }
182 // Otherwise return "L op' R" if it simplifies.
183 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
184 ++NumExpand;
185 return V;
186 }
187 }
188 }
189
190 return nullptr;
191 }
192
193 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
194 /// operations. Returns the simpler value, or null if none was found.
SimplifyAssociativeBinOp(unsigned Opc,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)195 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
196 const Query &Q, unsigned MaxRecurse) {
197 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
198 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
199
200 // Recursion is always used, so bail out at once if we already hit the limit.
201 if (!MaxRecurse--)
202 return nullptr;
203
204 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
205 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
206
207 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
208 if (Op0 && Op0->getOpcode() == Opcode) {
209 Value *A = Op0->getOperand(0);
210 Value *B = Op0->getOperand(1);
211 Value *C = RHS;
212
213 // Does "B op C" simplify?
214 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
215 // It does! Return "A op V" if it simplifies or is already available.
216 // If V equals B then "A op V" is just the LHS.
217 if (V == B) return LHS;
218 // Otherwise return "A op V" if it simplifies.
219 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
220 ++NumReassoc;
221 return W;
222 }
223 }
224 }
225
226 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
227 if (Op1 && Op1->getOpcode() == Opcode) {
228 Value *A = LHS;
229 Value *B = Op1->getOperand(0);
230 Value *C = Op1->getOperand(1);
231
232 // Does "A op B" simplify?
233 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
234 // It does! Return "V op C" if it simplifies or is already available.
235 // If V equals B then "V op C" is just the RHS.
236 if (V == B) return RHS;
237 // Otherwise return "V op C" if it simplifies.
238 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
239 ++NumReassoc;
240 return W;
241 }
242 }
243 }
244
245 // The remaining transforms require commutativity as well as associativity.
246 if (!Instruction::isCommutative(Opcode))
247 return nullptr;
248
249 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
250 if (Op0 && Op0->getOpcode() == Opcode) {
251 Value *A = Op0->getOperand(0);
252 Value *B = Op0->getOperand(1);
253 Value *C = RHS;
254
255 // Does "C op A" simplify?
256 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
257 // It does! Return "V op B" if it simplifies or is already available.
258 // If V equals A then "V op B" is just the LHS.
259 if (V == A) return LHS;
260 // Otherwise return "V op B" if it simplifies.
261 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
262 ++NumReassoc;
263 return W;
264 }
265 }
266 }
267
268 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
269 if (Op1 && Op1->getOpcode() == Opcode) {
270 Value *A = LHS;
271 Value *B = Op1->getOperand(0);
272 Value *C = Op1->getOperand(1);
273
274 // Does "C op A" simplify?
275 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
276 // It does! Return "B op V" if it simplifies or is already available.
277 // If V equals C then "B op V" is just the RHS.
278 if (V == C) return RHS;
279 // Otherwise return "B op V" if it simplifies.
280 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
281 ++NumReassoc;
282 return W;
283 }
284 }
285 }
286
287 return nullptr;
288 }
289
290 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
291 /// instruction as an operand, try to simplify the binop by seeing whether
292 /// evaluating it on both branches of the select results in the same value.
293 /// Returns the common value if so, otherwise returns null.
ThreadBinOpOverSelect(unsigned Opcode,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)294 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
295 const Query &Q, unsigned MaxRecurse) {
296 // Recursion is always used, so bail out at once if we already hit the limit.
297 if (!MaxRecurse--)
298 return nullptr;
299
300 SelectInst *SI;
301 if (isa<SelectInst>(LHS)) {
302 SI = cast<SelectInst>(LHS);
303 } else {
304 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
305 SI = cast<SelectInst>(RHS);
306 }
307
308 // Evaluate the BinOp on the true and false branches of the select.
309 Value *TV;
310 Value *FV;
311 if (SI == LHS) {
312 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
313 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
314 } else {
315 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
316 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
317 }
318
319 // If they simplified to the same value, then return the common value.
320 // If they both failed to simplify then return null.
321 if (TV == FV)
322 return TV;
323
324 // If one branch simplified to undef, return the other one.
325 if (TV && isa<UndefValue>(TV))
326 return FV;
327 if (FV && isa<UndefValue>(FV))
328 return TV;
329
330 // If applying the operation did not change the true and false select values,
331 // then the result of the binop is the select itself.
332 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
333 return SI;
334
335 // If one branch simplified and the other did not, and the simplified
336 // value is equal to the unsimplified one, return the simplified value.
337 // For example, select (cond, X, X & Z) & Z -> X & Z.
338 if ((FV && !TV) || (TV && !FV)) {
339 // Check that the simplified value has the form "X op Y" where "op" is the
340 // same as the original operation.
341 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
342 if (Simplified && Simplified->getOpcode() == Opcode) {
343 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
344 // We already know that "op" is the same as for the simplified value. See
345 // if the operands match too. If so, return the simplified value.
346 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
347 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
348 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
349 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
350 Simplified->getOperand(1) == UnsimplifiedRHS)
351 return Simplified;
352 if (Simplified->isCommutative() &&
353 Simplified->getOperand(1) == UnsimplifiedLHS &&
354 Simplified->getOperand(0) == UnsimplifiedRHS)
355 return Simplified;
356 }
357 }
358
359 return nullptr;
360 }
361
362 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
363 /// try to simplify the comparison by seeing whether both branches of the select
364 /// result in the same value. Returns the common value if so, otherwise returns
365 /// null.
ThreadCmpOverSelect(CmpInst::Predicate Pred,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)366 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
367 Value *RHS, const Query &Q,
368 unsigned MaxRecurse) {
369 // Recursion is always used, so bail out at once if we already hit the limit.
370 if (!MaxRecurse--)
371 return nullptr;
372
373 // Make sure the select is on the LHS.
374 if (!isa<SelectInst>(LHS)) {
375 std::swap(LHS, RHS);
376 Pred = CmpInst::getSwappedPredicate(Pred);
377 }
378 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
379 SelectInst *SI = cast<SelectInst>(LHS);
380 Value *Cond = SI->getCondition();
381 Value *TV = SI->getTrueValue();
382 Value *FV = SI->getFalseValue();
383
384 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
385 // Does "cmp TV, RHS" simplify?
386 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
387 if (TCmp == Cond) {
388 // It not only simplified, it simplified to the select condition. Replace
389 // it with 'true'.
390 TCmp = getTrue(Cond->getType());
391 } else if (!TCmp) {
392 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
393 // condition then we can replace it with 'true'. Otherwise give up.
394 if (!isSameCompare(Cond, Pred, TV, RHS))
395 return nullptr;
396 TCmp = getTrue(Cond->getType());
397 }
398
399 // Does "cmp FV, RHS" simplify?
400 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
401 if (FCmp == Cond) {
402 // It not only simplified, it simplified to the select condition. Replace
403 // it with 'false'.
404 FCmp = getFalse(Cond->getType());
405 } else if (!FCmp) {
406 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
407 // condition then we can replace it with 'false'. Otherwise give up.
408 if (!isSameCompare(Cond, Pred, FV, RHS))
409 return nullptr;
410 FCmp = getFalse(Cond->getType());
411 }
412
413 // If both sides simplified to the same value, then use it as the result of
414 // the original comparison.
415 if (TCmp == FCmp)
416 return TCmp;
417
418 // The remaining cases only make sense if the select condition has the same
419 // type as the result of the comparison, so bail out if this is not so.
420 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
421 return nullptr;
422 // If the false value simplified to false, then the result of the compare
423 // is equal to "Cond && TCmp". This also catches the case when the false
424 // value simplified to false and the true value to true, returning "Cond".
425 if (match(FCmp, m_Zero()))
426 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
427 return V;
428 // If the true value simplified to true, then the result of the compare
429 // is equal to "Cond || FCmp".
430 if (match(TCmp, m_One()))
431 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
432 return V;
433 // Finally, if the false value simplified to true and the true value to
434 // false, then the result of the compare is equal to "!Cond".
435 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
436 if (Value *V =
437 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
438 Q, MaxRecurse))
439 return V;
440
441 return nullptr;
442 }
443
444 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
445 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
446 /// it on the incoming phi values yields the same result for every value. If so
447 /// returns the common value, otherwise returns null.
ThreadBinOpOverPHI(unsigned Opcode,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)448 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
449 const Query &Q, unsigned MaxRecurse) {
450 // Recursion is always used, so bail out at once if we already hit the limit.
451 if (!MaxRecurse--)
452 return nullptr;
453
454 PHINode *PI;
455 if (isa<PHINode>(LHS)) {
456 PI = cast<PHINode>(LHS);
457 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
458 if (!ValueDominatesPHI(RHS, PI, Q.DT))
459 return nullptr;
460 } else {
461 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
462 PI = cast<PHINode>(RHS);
463 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
464 if (!ValueDominatesPHI(LHS, PI, Q.DT))
465 return nullptr;
466 }
467
468 // Evaluate the BinOp on the incoming phi values.
469 Value *CommonValue = nullptr;
470 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
471 Value *Incoming = PI->getIncomingValue(i);
472 // If the incoming value is the phi node itself, it can safely be skipped.
473 if (Incoming == PI) continue;
474 Value *V = PI == LHS ?
475 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
476 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
477 // If the operation failed to simplify, or simplified to a different value
478 // to previously, then give up.
479 if (!V || (CommonValue && V != CommonValue))
480 return nullptr;
481 CommonValue = V;
482 }
483
484 return CommonValue;
485 }
486
487 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
488 /// try to simplify the comparison by seeing whether comparing with all of the
489 /// incoming phi values yields the same result every time. If so returns the
490 /// common result, otherwise returns null.
ThreadCmpOverPHI(CmpInst::Predicate Pred,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)491 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
492 const Query &Q, unsigned MaxRecurse) {
493 // Recursion is always used, so bail out at once if we already hit the limit.
494 if (!MaxRecurse--)
495 return nullptr;
496
497 // Make sure the phi is on the LHS.
498 if (!isa<PHINode>(LHS)) {
499 std::swap(LHS, RHS);
500 Pred = CmpInst::getSwappedPredicate(Pred);
501 }
502 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
503 PHINode *PI = cast<PHINode>(LHS);
504
505 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
506 if (!ValueDominatesPHI(RHS, PI, Q.DT))
507 return nullptr;
508
509 // Evaluate the BinOp on the incoming phi values.
510 Value *CommonValue = nullptr;
511 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
512 Value *Incoming = PI->getIncomingValue(i);
513 // If the incoming value is the phi node itself, it can safely be skipped.
514 if (Incoming == PI) continue;
515 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
516 // If the operation failed to simplify, or simplified to a different value
517 // to previously, then give up.
518 if (!V || (CommonValue && V != CommonValue))
519 return nullptr;
520 CommonValue = V;
521 }
522
523 return CommonValue;
524 }
525
526 /// SimplifyAddInst - Given operands for an Add, see if we can
527 /// fold the result. If not, this returns null.
SimplifyAddInst(Value * Op0,Value * Op1,bool isNSW,bool isNUW,const Query & Q,unsigned MaxRecurse)528 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
529 const Query &Q, unsigned MaxRecurse) {
530 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
531 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
532 Constant *Ops[] = { CLHS, CRHS };
533 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops,
534 Q.DL, Q.TLI);
535 }
536
537 // Canonicalize the constant to the RHS.
538 std::swap(Op0, Op1);
539 }
540
541 // X + undef -> undef
542 if (match(Op1, m_Undef()))
543 return Op1;
544
545 // X + 0 -> X
546 if (match(Op1, m_Zero()))
547 return Op0;
548
549 // X + (Y - X) -> Y
550 // (Y - X) + X -> Y
551 // Eg: X + -X -> 0
552 Value *Y = nullptr;
553 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
554 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
555 return Y;
556
557 // X + ~X -> -1 since ~X = -X-1
558 if (match(Op0, m_Not(m_Specific(Op1))) ||
559 match(Op1, m_Not(m_Specific(Op0))))
560 return Constant::getAllOnesValue(Op0->getType());
561
562 /// i1 add -> xor.
563 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
564 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
565 return V;
566
567 // Try some generic simplifications for associative operations.
568 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
569 MaxRecurse))
570 return V;
571
572 // Threading Add over selects and phi nodes is pointless, so don't bother.
573 // Threading over the select in "A + select(cond, B, C)" means evaluating
574 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
575 // only if B and C are equal. If B and C are equal then (since we assume
576 // that operands have already been simplified) "select(cond, B, C)" should
577 // have been simplified to the common value of B and C already. Analysing
578 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
579 // for threading over phi nodes.
580
581 return nullptr;
582 }
583
SimplifyAddInst(Value * Op0,Value * Op1,bool isNSW,bool isNUW,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)584 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
585 const DataLayout *DL, const TargetLibraryInfo *TLI,
586 const DominatorTree *DT, AssumptionCache *AC,
587 const Instruction *CxtI) {
588 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
589 RecursionLimit);
590 }
591
592 /// \brief Compute the base pointer and cumulative constant offsets for V.
593 ///
594 /// This strips all constant offsets off of V, leaving it the base pointer, and
595 /// accumulates the total constant offset applied in the returned constant. It
596 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
597 /// no constant offsets applied.
598 ///
599 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
600 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
601 /// folding.
stripAndComputeConstantOffsets(const DataLayout * DL,Value * & V,bool AllowNonInbounds=false)602 static Constant *stripAndComputeConstantOffsets(const DataLayout *DL,
603 Value *&V,
604 bool AllowNonInbounds = false) {
605 assert(V->getType()->getScalarType()->isPointerTy());
606
607 // Without DataLayout, just be conservative for now. Theoretically, more could
608 // be done in this case.
609 if (!DL)
610 return ConstantInt::get(IntegerType::get(V->getContext(), 64), 0);
611
612 Type *IntPtrTy = DL->getIntPtrType(V->getType())->getScalarType();
613 APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
614
615 // Even though we don't look through PHI nodes, we could be called on an
616 // instruction in an unreachable block, which may be on a cycle.
617 SmallPtrSet<Value *, 4> Visited;
618 Visited.insert(V);
619 do {
620 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
621 if ((!AllowNonInbounds && !GEP->isInBounds()) ||
622 !GEP->accumulateConstantOffset(*DL, Offset))
623 break;
624 V = GEP->getPointerOperand();
625 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
626 V = cast<Operator>(V)->getOperand(0);
627 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
628 if (GA->mayBeOverridden())
629 break;
630 V = GA->getAliasee();
631 } else {
632 break;
633 }
634 assert(V->getType()->getScalarType()->isPointerTy() &&
635 "Unexpected operand type!");
636 } while (Visited.insert(V).second);
637
638 Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
639 if (V->getType()->isVectorTy())
640 return ConstantVector::getSplat(V->getType()->getVectorNumElements(),
641 OffsetIntPtr);
642 return OffsetIntPtr;
643 }
644
645 /// \brief Compute the constant difference between two pointer values.
646 /// If the difference is not a constant, returns zero.
computePointerDifference(const DataLayout * DL,Value * LHS,Value * RHS)647 static Constant *computePointerDifference(const DataLayout *DL,
648 Value *LHS, Value *RHS) {
649 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
650 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
651
652 // If LHS and RHS are not related via constant offsets to the same base
653 // value, there is nothing we can do here.
654 if (LHS != RHS)
655 return nullptr;
656
657 // Otherwise, the difference of LHS - RHS can be computed as:
658 // LHS - RHS
659 // = (LHSOffset + Base) - (RHSOffset + Base)
660 // = LHSOffset - RHSOffset
661 return ConstantExpr::getSub(LHSOffset, RHSOffset);
662 }
663
664 /// SimplifySubInst - Given operands for a Sub, see if we can
665 /// fold the result. If not, this returns null.
SimplifySubInst(Value * Op0,Value * Op1,bool isNSW,bool isNUW,const Query & Q,unsigned MaxRecurse)666 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
667 const Query &Q, unsigned MaxRecurse) {
668 if (Constant *CLHS = dyn_cast<Constant>(Op0))
669 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
670 Constant *Ops[] = { CLHS, CRHS };
671 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
672 Ops, Q.DL, Q.TLI);
673 }
674
675 // X - undef -> undef
676 // undef - X -> undef
677 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
678 return UndefValue::get(Op0->getType());
679
680 // X - 0 -> X
681 if (match(Op1, m_Zero()))
682 return Op0;
683
684 // X - X -> 0
685 if (Op0 == Op1)
686 return Constant::getNullValue(Op0->getType());
687
688 // 0 - X -> 0 if the sub is NUW.
689 if (isNUW && match(Op0, m_Zero()))
690 return Op0;
691
692 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
693 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
694 Value *X = nullptr, *Y = nullptr, *Z = Op1;
695 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
696 // See if "V === Y - Z" simplifies.
697 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
698 // It does! Now see if "X + V" simplifies.
699 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
700 // It does, we successfully reassociated!
701 ++NumReassoc;
702 return W;
703 }
704 // See if "V === X - Z" simplifies.
705 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
706 // It does! Now see if "Y + V" simplifies.
707 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
708 // It does, we successfully reassociated!
709 ++NumReassoc;
710 return W;
711 }
712 }
713
714 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
715 // For example, X - (X + 1) -> -1
716 X = Op0;
717 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
718 // See if "V === X - Y" simplifies.
719 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
720 // It does! Now see if "V - Z" simplifies.
721 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
722 // It does, we successfully reassociated!
723 ++NumReassoc;
724 return W;
725 }
726 // See if "V === X - Z" simplifies.
727 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
728 // It does! Now see if "V - Y" simplifies.
729 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
730 // It does, we successfully reassociated!
731 ++NumReassoc;
732 return W;
733 }
734 }
735
736 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
737 // For example, X - (X - Y) -> Y.
738 Z = Op0;
739 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
740 // See if "V === Z - X" simplifies.
741 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
742 // It does! Now see if "V + Y" simplifies.
743 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
744 // It does, we successfully reassociated!
745 ++NumReassoc;
746 return W;
747 }
748
749 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
750 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
751 match(Op1, m_Trunc(m_Value(Y))))
752 if (X->getType() == Y->getType())
753 // See if "V === X - Y" simplifies.
754 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
755 // It does! Now see if "trunc V" simplifies.
756 if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1))
757 // It does, return the simplified "trunc V".
758 return W;
759
760 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
761 if (match(Op0, m_PtrToInt(m_Value(X))) &&
762 match(Op1, m_PtrToInt(m_Value(Y))))
763 if (Constant *Result = computePointerDifference(Q.DL, X, Y))
764 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
765
766 // i1 sub -> xor.
767 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
768 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
769 return V;
770
771 // Threading Sub over selects and phi nodes is pointless, so don't bother.
772 // Threading over the select in "A - select(cond, B, C)" means evaluating
773 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
774 // only if B and C are equal. If B and C are equal then (since we assume
775 // that operands have already been simplified) "select(cond, B, C)" should
776 // have been simplified to the common value of B and C already. Analysing
777 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
778 // for threading over phi nodes.
779
780 return nullptr;
781 }
782
SimplifySubInst(Value * Op0,Value * Op1,bool isNSW,bool isNUW,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)783 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
784 const DataLayout *DL, const TargetLibraryInfo *TLI,
785 const DominatorTree *DT, AssumptionCache *AC,
786 const Instruction *CxtI) {
787 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
788 RecursionLimit);
789 }
790
791 /// Given operands for an FAdd, see if we can fold the result. If not, this
792 /// returns null.
SimplifyFAddInst(Value * Op0,Value * Op1,FastMathFlags FMF,const Query & Q,unsigned MaxRecurse)793 static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
794 const Query &Q, unsigned MaxRecurse) {
795 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
796 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
797 Constant *Ops[] = { CLHS, CRHS };
798 return ConstantFoldInstOperands(Instruction::FAdd, CLHS->getType(),
799 Ops, Q.DL, Q.TLI);
800 }
801
802 // Canonicalize the constant to the RHS.
803 std::swap(Op0, Op1);
804 }
805
806 // fadd X, -0 ==> X
807 if (match(Op1, m_NegZero()))
808 return Op0;
809
810 // fadd X, 0 ==> X, when we know X is not -0
811 if (match(Op1, m_Zero()) &&
812 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0)))
813 return Op0;
814
815 // fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
816 // where nnan and ninf have to occur at least once somewhere in this
817 // expression
818 Value *SubOp = nullptr;
819 if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0))))
820 SubOp = Op1;
821 else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1))))
822 SubOp = Op0;
823 if (SubOp) {
824 Instruction *FSub = cast<Instruction>(SubOp);
825 if ((FMF.noNaNs() || FSub->hasNoNaNs()) &&
826 (FMF.noInfs() || FSub->hasNoInfs()))
827 return Constant::getNullValue(Op0->getType());
828 }
829
830 return nullptr;
831 }
832
833 /// Given operands for an FSub, see if we can fold the result. If not, this
834 /// returns null.
SimplifyFSubInst(Value * Op0,Value * Op1,FastMathFlags FMF,const Query & Q,unsigned MaxRecurse)835 static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
836 const Query &Q, unsigned MaxRecurse) {
837 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
838 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
839 Constant *Ops[] = { CLHS, CRHS };
840 return ConstantFoldInstOperands(Instruction::FSub, CLHS->getType(),
841 Ops, Q.DL, Q.TLI);
842 }
843 }
844
845 // fsub X, 0 ==> X
846 if (match(Op1, m_Zero()))
847 return Op0;
848
849 // fsub X, -0 ==> X, when we know X is not -0
850 if (match(Op1, m_NegZero()) &&
851 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0)))
852 return Op0;
853
854 // fsub 0, (fsub -0.0, X) ==> X
855 Value *X;
856 if (match(Op0, m_AnyZero())) {
857 if (match(Op1, m_FSub(m_NegZero(), m_Value(X))))
858 return X;
859 if (FMF.noSignedZeros() && match(Op1, m_FSub(m_AnyZero(), m_Value(X))))
860 return X;
861 }
862
863 // fsub nnan ninf x, x ==> 0.0
864 if (FMF.noNaNs() && FMF.noInfs() && Op0 == Op1)
865 return Constant::getNullValue(Op0->getType());
866
867 return nullptr;
868 }
869
870 /// Given the operands for an FMul, see if we can fold the result
SimplifyFMulInst(Value * Op0,Value * Op1,FastMathFlags FMF,const Query & Q,unsigned MaxRecurse)871 static Value *SimplifyFMulInst(Value *Op0, Value *Op1,
872 FastMathFlags FMF,
873 const Query &Q,
874 unsigned MaxRecurse) {
875 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
876 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
877 Constant *Ops[] = { CLHS, CRHS };
878 return ConstantFoldInstOperands(Instruction::FMul, CLHS->getType(),
879 Ops, Q.DL, Q.TLI);
880 }
881
882 // Canonicalize the constant to the RHS.
883 std::swap(Op0, Op1);
884 }
885
886 // fmul X, 1.0 ==> X
887 if (match(Op1, m_FPOne()))
888 return Op0;
889
890 // fmul nnan nsz X, 0 ==> 0
891 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero()))
892 return Op1;
893
894 return nullptr;
895 }
896
897 /// SimplifyMulInst - Given operands for a Mul, see if we can
898 /// fold the result. If not, this returns null.
SimplifyMulInst(Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)899 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
900 unsigned MaxRecurse) {
901 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
902 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
903 Constant *Ops[] = { CLHS, CRHS };
904 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
905 Ops, Q.DL, Q.TLI);
906 }
907
908 // Canonicalize the constant to the RHS.
909 std::swap(Op0, Op1);
910 }
911
912 // X * undef -> 0
913 if (match(Op1, m_Undef()))
914 return Constant::getNullValue(Op0->getType());
915
916 // X * 0 -> 0
917 if (match(Op1, m_Zero()))
918 return Op1;
919
920 // X * 1 -> X
921 if (match(Op1, m_One()))
922 return Op0;
923
924 // (X / Y) * Y -> X if the division is exact.
925 Value *X = nullptr;
926 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
927 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
928 return X;
929
930 // i1 mul -> and.
931 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
932 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
933 return V;
934
935 // Try some generic simplifications for associative operations.
936 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
937 MaxRecurse))
938 return V;
939
940 // Mul distributes over Add. Try some generic simplifications based on this.
941 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
942 Q, MaxRecurse))
943 return V;
944
945 // If the operation is with the result of a select instruction, check whether
946 // operating on either branch of the select always yields the same value.
947 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
948 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
949 MaxRecurse))
950 return V;
951
952 // If the operation is with the result of a phi instruction, check whether
953 // operating on all incoming values of the phi always yields the same value.
954 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
955 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
956 MaxRecurse))
957 return V;
958
959 return nullptr;
960 }
961
SimplifyFAddInst(Value * Op0,Value * Op1,FastMathFlags FMF,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)962 Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
963 const DataLayout *DL,
964 const TargetLibraryInfo *TLI,
965 const DominatorTree *DT, AssumptionCache *AC,
966 const Instruction *CxtI) {
967 return ::SimplifyFAddInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
968 RecursionLimit);
969 }
970
SimplifyFSubInst(Value * Op0,Value * Op1,FastMathFlags FMF,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)971 Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
972 const DataLayout *DL,
973 const TargetLibraryInfo *TLI,
974 const DominatorTree *DT, AssumptionCache *AC,
975 const Instruction *CxtI) {
976 return ::SimplifyFSubInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
977 RecursionLimit);
978 }
979
SimplifyFMulInst(Value * Op0,Value * Op1,FastMathFlags FMF,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)980 Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
981 const DataLayout *DL,
982 const TargetLibraryInfo *TLI,
983 const DominatorTree *DT, AssumptionCache *AC,
984 const Instruction *CxtI) {
985 return ::SimplifyFMulInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
986 RecursionLimit);
987 }
988
SimplifyMulInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)989 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const DataLayout *DL,
990 const TargetLibraryInfo *TLI,
991 const DominatorTree *DT, AssumptionCache *AC,
992 const Instruction *CxtI) {
993 return ::SimplifyMulInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
994 RecursionLimit);
995 }
996
997 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
998 /// fold the result. If not, this returns null.
SimplifyDiv(Instruction::BinaryOps Opcode,Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)999 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1000 const Query &Q, unsigned MaxRecurse) {
1001 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1002 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1003 Constant *Ops[] = { C0, C1 };
1004 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1005 }
1006 }
1007
1008 bool isSigned = Opcode == Instruction::SDiv;
1009
1010 // X / undef -> undef
1011 if (match(Op1, m_Undef()))
1012 return Op1;
1013
1014 // X / 0 -> undef, we don't need to preserve faults!
1015 if (match(Op1, m_Zero()))
1016 return UndefValue::get(Op1->getType());
1017
1018 // undef / X -> 0
1019 if (match(Op0, m_Undef()))
1020 return Constant::getNullValue(Op0->getType());
1021
1022 // 0 / X -> 0, we don't need to preserve faults!
1023 if (match(Op0, m_Zero()))
1024 return Op0;
1025
1026 // X / 1 -> X
1027 if (match(Op1, m_One()))
1028 return Op0;
1029
1030 if (Op0->getType()->isIntegerTy(1))
1031 // It can't be division by zero, hence it must be division by one.
1032 return Op0;
1033
1034 // X / X -> 1
1035 if (Op0 == Op1)
1036 return ConstantInt::get(Op0->getType(), 1);
1037
1038 // (X * Y) / Y -> X if the multiplication does not overflow.
1039 Value *X = nullptr, *Y = nullptr;
1040 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
1041 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
1042 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
1043 // If the Mul knows it does not overflow, then we are good to go.
1044 if ((isSigned && Mul->hasNoSignedWrap()) ||
1045 (!isSigned && Mul->hasNoUnsignedWrap()))
1046 return X;
1047 // If X has the form X = A / Y then X * Y cannot overflow.
1048 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
1049 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1050 return X;
1051 }
1052
1053 // (X rem Y) / Y -> 0
1054 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1055 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1056 return Constant::getNullValue(Op0->getType());
1057
1058 // (X /u C1) /u C2 -> 0 if C1 * C2 overflow
1059 ConstantInt *C1, *C2;
1060 if (!isSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
1061 match(Op1, m_ConstantInt(C2))) {
1062 bool Overflow;
1063 C1->getValue().umul_ov(C2->getValue(), Overflow);
1064 if (Overflow)
1065 return Constant::getNullValue(Op0->getType());
1066 }
1067
1068 // If the operation is with the result of a select instruction, check whether
1069 // operating on either branch of the select always yields the same value.
1070 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1071 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1072 return V;
1073
1074 // If the operation is with the result of a phi instruction, check whether
1075 // operating on all incoming values of the phi always yields the same value.
1076 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1077 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1078 return V;
1079
1080 return nullptr;
1081 }
1082
1083 /// SimplifySDivInst - Given operands for an SDiv, see if we can
1084 /// fold the result. If not, this returns null.
SimplifySDivInst(Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1085 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
1086 unsigned MaxRecurse) {
1087 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
1088 return V;
1089
1090 return nullptr;
1091 }
1092
SimplifySDivInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1093 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const DataLayout *DL,
1094 const TargetLibraryInfo *TLI,
1095 const DominatorTree *DT, AssumptionCache *AC,
1096 const Instruction *CxtI) {
1097 return ::SimplifySDivInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1098 RecursionLimit);
1099 }
1100
1101 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
1102 /// fold the result. If not, this returns null.
SimplifyUDivInst(Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1103 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
1104 unsigned MaxRecurse) {
1105 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
1106 return V;
1107
1108 return nullptr;
1109 }
1110
SimplifyUDivInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1111 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const DataLayout *DL,
1112 const TargetLibraryInfo *TLI,
1113 const DominatorTree *DT, AssumptionCache *AC,
1114 const Instruction *CxtI) {
1115 return ::SimplifyUDivInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1116 RecursionLimit);
1117 }
1118
SimplifyFDivInst(Value * Op0,Value * Op1,const Query & Q,unsigned)1119 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q,
1120 unsigned) {
1121 // undef / X -> undef (the undef could be a snan).
1122 if (match(Op0, m_Undef()))
1123 return Op0;
1124
1125 // X / undef -> undef
1126 if (match(Op1, m_Undef()))
1127 return Op1;
1128
1129 return nullptr;
1130 }
1131
SimplifyFDivInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1132 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const DataLayout *DL,
1133 const TargetLibraryInfo *TLI,
1134 const DominatorTree *DT, AssumptionCache *AC,
1135 const Instruction *CxtI) {
1136 return ::SimplifyFDivInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1137 RecursionLimit);
1138 }
1139
1140 /// SimplifyRem - Given operands for an SRem or URem, see if we can
1141 /// fold the result. If not, this returns null.
SimplifyRem(Instruction::BinaryOps Opcode,Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1142 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1143 const Query &Q, unsigned MaxRecurse) {
1144 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1145 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1146 Constant *Ops[] = { C0, C1 };
1147 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1148 }
1149 }
1150
1151 // X % undef -> undef
1152 if (match(Op1, m_Undef()))
1153 return Op1;
1154
1155 // undef % X -> 0
1156 if (match(Op0, m_Undef()))
1157 return Constant::getNullValue(Op0->getType());
1158
1159 // 0 % X -> 0, we don't need to preserve faults!
1160 if (match(Op0, m_Zero()))
1161 return Op0;
1162
1163 // X % 0 -> undef, we don't need to preserve faults!
1164 if (match(Op1, m_Zero()))
1165 return UndefValue::get(Op0->getType());
1166
1167 // X % 1 -> 0
1168 if (match(Op1, m_One()))
1169 return Constant::getNullValue(Op0->getType());
1170
1171 if (Op0->getType()->isIntegerTy(1))
1172 // It can't be remainder by zero, hence it must be remainder by one.
1173 return Constant::getNullValue(Op0->getType());
1174
1175 // X % X -> 0
1176 if (Op0 == Op1)
1177 return Constant::getNullValue(Op0->getType());
1178
1179 // (X % Y) % Y -> X % Y
1180 if ((Opcode == Instruction::SRem &&
1181 match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1182 (Opcode == Instruction::URem &&
1183 match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1184 return Op0;
1185
1186 // If the operation is with the result of a select instruction, check whether
1187 // operating on either branch of the select always yields the same value.
1188 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1189 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1190 return V;
1191
1192 // If the operation is with the result of a phi instruction, check whether
1193 // operating on all incoming values of the phi always yields the same value.
1194 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1195 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1196 return V;
1197
1198 return nullptr;
1199 }
1200
1201 /// SimplifySRemInst - Given operands for an SRem, see if we can
1202 /// fold the result. If not, this returns null.
SimplifySRemInst(Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1203 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
1204 unsigned MaxRecurse) {
1205 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
1206 return V;
1207
1208 return nullptr;
1209 }
1210
SimplifySRemInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1211 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const DataLayout *DL,
1212 const TargetLibraryInfo *TLI,
1213 const DominatorTree *DT, AssumptionCache *AC,
1214 const Instruction *CxtI) {
1215 return ::SimplifySRemInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1216 RecursionLimit);
1217 }
1218
1219 /// SimplifyURemInst - Given operands for a URem, see if we can
1220 /// fold the result. If not, this returns null.
SimplifyURemInst(Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1221 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
1222 unsigned MaxRecurse) {
1223 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
1224 return V;
1225
1226 return nullptr;
1227 }
1228
SimplifyURemInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1229 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const DataLayout *DL,
1230 const TargetLibraryInfo *TLI,
1231 const DominatorTree *DT, AssumptionCache *AC,
1232 const Instruction *CxtI) {
1233 return ::SimplifyURemInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1234 RecursionLimit);
1235 }
1236
SimplifyFRemInst(Value * Op0,Value * Op1,const Query &,unsigned)1237 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &,
1238 unsigned) {
1239 // undef % X -> undef (the undef could be a snan).
1240 if (match(Op0, m_Undef()))
1241 return Op0;
1242
1243 // X % undef -> undef
1244 if (match(Op1, m_Undef()))
1245 return Op1;
1246
1247 return nullptr;
1248 }
1249
SimplifyFRemInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1250 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const DataLayout *DL,
1251 const TargetLibraryInfo *TLI,
1252 const DominatorTree *DT, AssumptionCache *AC,
1253 const Instruction *CxtI) {
1254 return ::SimplifyFRemInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1255 RecursionLimit);
1256 }
1257
1258 /// isUndefShift - Returns true if a shift by \c Amount always yields undef.
isUndefShift(Value * Amount)1259 static bool isUndefShift(Value *Amount) {
1260 Constant *C = dyn_cast<Constant>(Amount);
1261 if (!C)
1262 return false;
1263
1264 // X shift by undef -> undef because it may shift by the bitwidth.
1265 if (isa<UndefValue>(C))
1266 return true;
1267
1268 // Shifting by the bitwidth or more is undefined.
1269 if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
1270 if (CI->getValue().getLimitedValue() >=
1271 CI->getType()->getScalarSizeInBits())
1272 return true;
1273
1274 // If all lanes of a vector shift are undefined the whole shift is.
1275 if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
1276 for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I)
1277 if (!isUndefShift(C->getAggregateElement(I)))
1278 return false;
1279 return true;
1280 }
1281
1282 return false;
1283 }
1284
1285 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1286 /// fold the result. If not, this returns null.
SimplifyShift(unsigned Opcode,Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1287 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1288 const Query &Q, unsigned MaxRecurse) {
1289 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1290 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1291 Constant *Ops[] = { C0, C1 };
1292 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.DL, Q.TLI);
1293 }
1294 }
1295
1296 // 0 shift by X -> 0
1297 if (match(Op0, m_Zero()))
1298 return Op0;
1299
1300 // X shift by 0 -> X
1301 if (match(Op1, m_Zero()))
1302 return Op0;
1303
1304 // Fold undefined shifts.
1305 if (isUndefShift(Op1))
1306 return UndefValue::get(Op0->getType());
1307
1308 // If the operation is with the result of a select instruction, check whether
1309 // operating on either branch of the select always yields the same value.
1310 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1311 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1312 return V;
1313
1314 // If the operation is with the result of a phi instruction, check whether
1315 // operating on all incoming values of the phi always yields the same value.
1316 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1317 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1318 return V;
1319
1320 return nullptr;
1321 }
1322
1323 /// \brief Given operands for an Shl, LShr or AShr, see if we can
1324 /// fold the result. If not, this returns null.
SimplifyRightShift(unsigned Opcode,Value * Op0,Value * Op1,bool isExact,const Query & Q,unsigned MaxRecurse)1325 static Value *SimplifyRightShift(unsigned Opcode, Value *Op0, Value *Op1,
1326 bool isExact, const Query &Q,
1327 unsigned MaxRecurse) {
1328 if (Value *V = SimplifyShift(Opcode, Op0, Op1, Q, MaxRecurse))
1329 return V;
1330
1331 // X >> X -> 0
1332 if (Op0 == Op1)
1333 return Constant::getNullValue(Op0->getType());
1334
1335 // undef >> X -> 0
1336 // undef >> X -> undef (if it's exact)
1337 if (match(Op0, m_Undef()))
1338 return isExact ? Op0 : Constant::getNullValue(Op0->getType());
1339
1340 // The low bit cannot be shifted out of an exact shift if it is set.
1341 if (isExact) {
1342 unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
1343 APInt Op0KnownZero(BitWidth, 0);
1344 APInt Op0KnownOne(BitWidth, 0);
1345 computeKnownBits(Op0, Op0KnownZero, Op0KnownOne, Q.DL, /*Depth=*/0, Q.AC,
1346 Q.CxtI, Q.DT);
1347 if (Op0KnownOne[0])
1348 return Op0;
1349 }
1350
1351 return nullptr;
1352 }
1353
1354 /// SimplifyShlInst - Given operands for an Shl, see if we can
1355 /// fold the result. If not, this returns null.
SimplifyShlInst(Value * Op0,Value * Op1,bool isNSW,bool isNUW,const Query & Q,unsigned MaxRecurse)1356 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1357 const Query &Q, unsigned MaxRecurse) {
1358 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1359 return V;
1360
1361 // undef << X -> 0
1362 // undef << X -> undef if (if it's NSW/NUW)
1363 if (match(Op0, m_Undef()))
1364 return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType());
1365
1366 // (X >> A) << A -> X
1367 Value *X;
1368 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1369 return X;
1370 return nullptr;
1371 }
1372
SimplifyShlInst(Value * Op0,Value * Op1,bool isNSW,bool isNUW,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1373 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1374 const DataLayout *DL, const TargetLibraryInfo *TLI,
1375 const DominatorTree *DT, AssumptionCache *AC,
1376 const Instruction *CxtI) {
1377 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
1378 RecursionLimit);
1379 }
1380
1381 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1382 /// fold the result. If not, this returns null.
SimplifyLShrInst(Value * Op0,Value * Op1,bool isExact,const Query & Q,unsigned MaxRecurse)1383 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1384 const Query &Q, unsigned MaxRecurse) {
1385 if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q,
1386 MaxRecurse))
1387 return V;
1388
1389 // (X << A) >> A -> X
1390 Value *X;
1391 if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
1392 return X;
1393
1394 return nullptr;
1395 }
1396
SimplifyLShrInst(Value * Op0,Value * Op1,bool isExact,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1397 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1398 const DataLayout *DL,
1399 const TargetLibraryInfo *TLI,
1400 const DominatorTree *DT, AssumptionCache *AC,
1401 const Instruction *CxtI) {
1402 return ::SimplifyLShrInst(Op0, Op1, isExact, Query(DL, TLI, DT, AC, CxtI),
1403 RecursionLimit);
1404 }
1405
1406 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1407 /// fold the result. If not, this returns null.
SimplifyAShrInst(Value * Op0,Value * Op1,bool isExact,const Query & Q,unsigned MaxRecurse)1408 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1409 const Query &Q, unsigned MaxRecurse) {
1410 if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
1411 MaxRecurse))
1412 return V;
1413
1414 // all ones >>a X -> all ones
1415 if (match(Op0, m_AllOnes()))
1416 return Op0;
1417
1418 // (X << A) >> A -> X
1419 Value *X;
1420 if (match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
1421 return X;
1422
1423 // Arithmetic shifting an all-sign-bit value is a no-op.
1424 unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1425 if (NumSignBits == Op0->getType()->getScalarSizeInBits())
1426 return Op0;
1427
1428 return nullptr;
1429 }
1430
SimplifyAShrInst(Value * Op0,Value * Op1,bool isExact,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1431 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1432 const DataLayout *DL,
1433 const TargetLibraryInfo *TLI,
1434 const DominatorTree *DT, AssumptionCache *AC,
1435 const Instruction *CxtI) {
1436 return ::SimplifyAShrInst(Op0, Op1, isExact, Query(DL, TLI, DT, AC, CxtI),
1437 RecursionLimit);
1438 }
1439
simplifyUnsignedRangeCheck(ICmpInst * ZeroICmp,ICmpInst * UnsignedICmp,bool IsAnd)1440 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp,
1441 ICmpInst *UnsignedICmp, bool IsAnd) {
1442 Value *X, *Y;
1443
1444 ICmpInst::Predicate EqPred;
1445 if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) ||
1446 !ICmpInst::isEquality(EqPred))
1447 return nullptr;
1448
1449 ICmpInst::Predicate UnsignedPred;
1450 if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
1451 ICmpInst::isUnsigned(UnsignedPred))
1452 ;
1453 else if (match(UnsignedICmp,
1454 m_ICmp(UnsignedPred, m_Value(Y), m_Specific(X))) &&
1455 ICmpInst::isUnsigned(UnsignedPred))
1456 UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
1457 else
1458 return nullptr;
1459
1460 // X < Y && Y != 0 --> X < Y
1461 // X < Y || Y != 0 --> Y != 0
1462 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE)
1463 return IsAnd ? UnsignedICmp : ZeroICmp;
1464
1465 // X >= Y || Y != 0 --> true
1466 // X >= Y || Y == 0 --> X >= Y
1467 if (UnsignedPred == ICmpInst::ICMP_UGE && !IsAnd) {
1468 if (EqPred == ICmpInst::ICMP_NE)
1469 return getTrue(UnsignedICmp->getType());
1470 return UnsignedICmp;
1471 }
1472
1473 // X < Y && Y == 0 --> false
1474 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
1475 IsAnd)
1476 return getFalse(UnsignedICmp->getType());
1477
1478 return nullptr;
1479 }
1480
1481 // Simplify (and (icmp ...) (icmp ...)) to true when we can tell that the range
1482 // of possible values cannot be satisfied.
SimplifyAndOfICmps(ICmpInst * Op0,ICmpInst * Op1)1483 static Value *SimplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
1484 ICmpInst::Predicate Pred0, Pred1;
1485 ConstantInt *CI1, *CI2;
1486 Value *V;
1487
1488 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true))
1489 return X;
1490
1491 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
1492 m_ConstantInt(CI2))))
1493 return nullptr;
1494
1495 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
1496 return nullptr;
1497
1498 Type *ITy = Op0->getType();
1499
1500 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1501 bool isNSW = AddInst->hasNoSignedWrap();
1502 bool isNUW = AddInst->hasNoUnsignedWrap();
1503
1504 const APInt &CI1V = CI1->getValue();
1505 const APInt &CI2V = CI2->getValue();
1506 const APInt Delta = CI2V - CI1V;
1507 if (CI1V.isStrictlyPositive()) {
1508 if (Delta == 2) {
1509 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
1510 return getFalse(ITy);
1511 if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1512 return getFalse(ITy);
1513 }
1514 if (Delta == 1) {
1515 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
1516 return getFalse(ITy);
1517 if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1518 return getFalse(ITy);
1519 }
1520 }
1521 if (CI1V.getBoolValue() && isNUW) {
1522 if (Delta == 2)
1523 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
1524 return getFalse(ITy);
1525 if (Delta == 1)
1526 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
1527 return getFalse(ITy);
1528 }
1529
1530 return nullptr;
1531 }
1532
1533 /// SimplifyAndInst - Given operands for an And, see if we can
1534 /// fold the result. If not, this returns null.
SimplifyAndInst(Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1535 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
1536 unsigned MaxRecurse) {
1537 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1538 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1539 Constant *Ops[] = { CLHS, CRHS };
1540 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1541 Ops, Q.DL, Q.TLI);
1542 }
1543
1544 // Canonicalize the constant to the RHS.
1545 std::swap(Op0, Op1);
1546 }
1547
1548 // X & undef -> 0
1549 if (match(Op1, m_Undef()))
1550 return Constant::getNullValue(Op0->getType());
1551
1552 // X & X = X
1553 if (Op0 == Op1)
1554 return Op0;
1555
1556 // X & 0 = 0
1557 if (match(Op1, m_Zero()))
1558 return Op1;
1559
1560 // X & -1 = X
1561 if (match(Op1, m_AllOnes()))
1562 return Op0;
1563
1564 // A & ~A = ~A & A = 0
1565 if (match(Op0, m_Not(m_Specific(Op1))) ||
1566 match(Op1, m_Not(m_Specific(Op0))))
1567 return Constant::getNullValue(Op0->getType());
1568
1569 // (A | ?) & A = A
1570 Value *A = nullptr, *B = nullptr;
1571 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1572 (A == Op1 || B == Op1))
1573 return Op1;
1574
1575 // A & (A | ?) = A
1576 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1577 (A == Op0 || B == Op0))
1578 return Op0;
1579
1580 // A & (-A) = A if A is a power of two or zero.
1581 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1582 match(Op1, m_Neg(m_Specific(Op0)))) {
1583 if (isKnownToBeAPowerOfTwo(Op0, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
1584 return Op0;
1585 if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
1586 return Op1;
1587 }
1588
1589 if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
1590 if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
1591 if (Value *V = SimplifyAndOfICmps(ICILHS, ICIRHS))
1592 return V;
1593 if (Value *V = SimplifyAndOfICmps(ICIRHS, ICILHS))
1594 return V;
1595 }
1596 }
1597
1598 // Try some generic simplifications for associative operations.
1599 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1600 MaxRecurse))
1601 return V;
1602
1603 // And distributes over Or. Try some generic simplifications based on this.
1604 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1605 Q, MaxRecurse))
1606 return V;
1607
1608 // And distributes over Xor. Try some generic simplifications based on this.
1609 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1610 Q, MaxRecurse))
1611 return V;
1612
1613 // If the operation is with the result of a select instruction, check whether
1614 // operating on either branch of the select always yields the same value.
1615 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1616 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1617 MaxRecurse))
1618 return V;
1619
1620 // If the operation is with the result of a phi instruction, check whether
1621 // operating on all incoming values of the phi always yields the same value.
1622 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1623 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1624 MaxRecurse))
1625 return V;
1626
1627 return nullptr;
1628 }
1629
SimplifyAndInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1630 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout *DL,
1631 const TargetLibraryInfo *TLI,
1632 const DominatorTree *DT, AssumptionCache *AC,
1633 const Instruction *CxtI) {
1634 return ::SimplifyAndInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1635 RecursionLimit);
1636 }
1637
1638 // Simplify (or (icmp ...) (icmp ...)) to true when we can tell that the union
1639 // contains all possible values.
SimplifyOrOfICmps(ICmpInst * Op0,ICmpInst * Op1)1640 static Value *SimplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
1641 ICmpInst::Predicate Pred0, Pred1;
1642 ConstantInt *CI1, *CI2;
1643 Value *V;
1644
1645 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false))
1646 return X;
1647
1648 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
1649 m_ConstantInt(CI2))))
1650 return nullptr;
1651
1652 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
1653 return nullptr;
1654
1655 Type *ITy = Op0->getType();
1656
1657 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1658 bool isNSW = AddInst->hasNoSignedWrap();
1659 bool isNUW = AddInst->hasNoUnsignedWrap();
1660
1661 const APInt &CI1V = CI1->getValue();
1662 const APInt &CI2V = CI2->getValue();
1663 const APInt Delta = CI2V - CI1V;
1664 if (CI1V.isStrictlyPositive()) {
1665 if (Delta == 2) {
1666 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
1667 return getTrue(ITy);
1668 if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1669 return getTrue(ITy);
1670 }
1671 if (Delta == 1) {
1672 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
1673 return getTrue(ITy);
1674 if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1675 return getTrue(ITy);
1676 }
1677 }
1678 if (CI1V.getBoolValue() && isNUW) {
1679 if (Delta == 2)
1680 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
1681 return getTrue(ITy);
1682 if (Delta == 1)
1683 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
1684 return getTrue(ITy);
1685 }
1686
1687 return nullptr;
1688 }
1689
1690 /// SimplifyOrInst - Given operands for an Or, see if we can
1691 /// fold the result. If not, this returns null.
SimplifyOrInst(Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1692 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
1693 unsigned MaxRecurse) {
1694 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1695 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1696 Constant *Ops[] = { CLHS, CRHS };
1697 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1698 Ops, Q.DL, Q.TLI);
1699 }
1700
1701 // Canonicalize the constant to the RHS.
1702 std::swap(Op0, Op1);
1703 }
1704
1705 // X | undef -> -1
1706 if (match(Op1, m_Undef()))
1707 return Constant::getAllOnesValue(Op0->getType());
1708
1709 // X | X = X
1710 if (Op0 == Op1)
1711 return Op0;
1712
1713 // X | 0 = X
1714 if (match(Op1, m_Zero()))
1715 return Op0;
1716
1717 // X | -1 = -1
1718 if (match(Op1, m_AllOnes()))
1719 return Op1;
1720
1721 // A | ~A = ~A | A = -1
1722 if (match(Op0, m_Not(m_Specific(Op1))) ||
1723 match(Op1, m_Not(m_Specific(Op0))))
1724 return Constant::getAllOnesValue(Op0->getType());
1725
1726 // (A & ?) | A = A
1727 Value *A = nullptr, *B = nullptr;
1728 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1729 (A == Op1 || B == Op1))
1730 return Op1;
1731
1732 // A | (A & ?) = A
1733 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1734 (A == Op0 || B == Op0))
1735 return Op0;
1736
1737 // ~(A & ?) | A = -1
1738 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1739 (A == Op1 || B == Op1))
1740 return Constant::getAllOnesValue(Op1->getType());
1741
1742 // A | ~(A & ?) = -1
1743 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1744 (A == Op0 || B == Op0))
1745 return Constant::getAllOnesValue(Op0->getType());
1746
1747 if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
1748 if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
1749 if (Value *V = SimplifyOrOfICmps(ICILHS, ICIRHS))
1750 return V;
1751 if (Value *V = SimplifyOrOfICmps(ICIRHS, ICILHS))
1752 return V;
1753 }
1754 }
1755
1756 // Try some generic simplifications for associative operations.
1757 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1758 MaxRecurse))
1759 return V;
1760
1761 // Or distributes over And. Try some generic simplifications based on this.
1762 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1763 MaxRecurse))
1764 return V;
1765
1766 // If the operation is with the result of a select instruction, check whether
1767 // operating on either branch of the select always yields the same value.
1768 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1769 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1770 MaxRecurse))
1771 return V;
1772
1773 // (A & C)|(B & D)
1774 Value *C = nullptr, *D = nullptr;
1775 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
1776 match(Op1, m_And(m_Value(B), m_Value(D)))) {
1777 ConstantInt *C1 = dyn_cast<ConstantInt>(C);
1778 ConstantInt *C2 = dyn_cast<ConstantInt>(D);
1779 if (C1 && C2 && (C1->getValue() == ~C2->getValue())) {
1780 // (A & C1)|(B & C2)
1781 // If we have: ((V + N) & C1) | (V & C2)
1782 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1783 // replace with V+N.
1784 Value *V1, *V2;
1785 if ((C2->getValue() & (C2->getValue() + 1)) == 0 && // C2 == 0+1+
1786 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
1787 // Add commutes, try both ways.
1788 if (V1 == B &&
1789 MaskedValueIsZero(V2, C2->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1790 return A;
1791 if (V2 == B &&
1792 MaskedValueIsZero(V1, C2->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1793 return A;
1794 }
1795 // Or commutes, try both ways.
1796 if ((C1->getValue() & (C1->getValue() + 1)) == 0 &&
1797 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
1798 // Add commutes, try both ways.
1799 if (V1 == A &&
1800 MaskedValueIsZero(V2, C1->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1801 return B;
1802 if (V2 == A &&
1803 MaskedValueIsZero(V1, C1->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1804 return B;
1805 }
1806 }
1807 }
1808
1809 // If the operation is with the result of a phi instruction, check whether
1810 // operating on all incoming values of the phi always yields the same value.
1811 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1812 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1813 return V;
1814
1815 return nullptr;
1816 }
1817
SimplifyOrInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1818 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const DataLayout *DL,
1819 const TargetLibraryInfo *TLI,
1820 const DominatorTree *DT, AssumptionCache *AC,
1821 const Instruction *CxtI) {
1822 return ::SimplifyOrInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1823 RecursionLimit);
1824 }
1825
1826 /// SimplifyXorInst - Given operands for a Xor, see if we can
1827 /// fold the result. If not, this returns null.
SimplifyXorInst(Value * Op0,Value * Op1,const Query & Q,unsigned MaxRecurse)1828 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q,
1829 unsigned MaxRecurse) {
1830 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1831 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1832 Constant *Ops[] = { CLHS, CRHS };
1833 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1834 Ops, Q.DL, Q.TLI);
1835 }
1836
1837 // Canonicalize the constant to the RHS.
1838 std::swap(Op0, Op1);
1839 }
1840
1841 // A ^ undef -> undef
1842 if (match(Op1, m_Undef()))
1843 return Op1;
1844
1845 // A ^ 0 = A
1846 if (match(Op1, m_Zero()))
1847 return Op0;
1848
1849 // A ^ A = 0
1850 if (Op0 == Op1)
1851 return Constant::getNullValue(Op0->getType());
1852
1853 // A ^ ~A = ~A ^ A = -1
1854 if (match(Op0, m_Not(m_Specific(Op1))) ||
1855 match(Op1, m_Not(m_Specific(Op0))))
1856 return Constant::getAllOnesValue(Op0->getType());
1857
1858 // Try some generic simplifications for associative operations.
1859 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1860 MaxRecurse))
1861 return V;
1862
1863 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1864 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1865 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1866 // only if B and C are equal. If B and C are equal then (since we assume
1867 // that operands have already been simplified) "select(cond, B, C)" should
1868 // have been simplified to the common value of B and C already. Analysing
1869 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1870 // for threading over phi nodes.
1871
1872 return nullptr;
1873 }
1874
SimplifyXorInst(Value * Op0,Value * Op1,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)1875 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const DataLayout *DL,
1876 const TargetLibraryInfo *TLI,
1877 const DominatorTree *DT, AssumptionCache *AC,
1878 const Instruction *CxtI) {
1879 return ::SimplifyXorInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
1880 RecursionLimit);
1881 }
1882
GetCompareTy(Value * Op)1883 static Type *GetCompareTy(Value *Op) {
1884 return CmpInst::makeCmpResultType(Op->getType());
1885 }
1886
1887 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1888 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1889 /// otherwise return null. Helper function for analyzing max/min idioms.
ExtractEquivalentCondition(Value * V,CmpInst::Predicate Pred,Value * LHS,Value * RHS)1890 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1891 Value *LHS, Value *RHS) {
1892 SelectInst *SI = dyn_cast<SelectInst>(V);
1893 if (!SI)
1894 return nullptr;
1895 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1896 if (!Cmp)
1897 return nullptr;
1898 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1899 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1900 return Cmp;
1901 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1902 LHS == CmpRHS && RHS == CmpLHS)
1903 return Cmp;
1904 return nullptr;
1905 }
1906
1907 // A significant optimization not implemented here is assuming that alloca
1908 // addresses are not equal to incoming argument values. They don't *alias*,
1909 // as we say, but that doesn't mean they aren't equal, so we take a
1910 // conservative approach.
1911 //
1912 // This is inspired in part by C++11 5.10p1:
1913 // "Two pointers of the same type compare equal if and only if they are both
1914 // null, both point to the same function, or both represent the same
1915 // address."
1916 //
1917 // This is pretty permissive.
1918 //
1919 // It's also partly due to C11 6.5.9p6:
1920 // "Two pointers compare equal if and only if both are null pointers, both are
1921 // pointers to the same object (including a pointer to an object and a
1922 // subobject at its beginning) or function, both are pointers to one past the
1923 // last element of the same array object, or one is a pointer to one past the
1924 // end of one array object and the other is a pointer to the start of a
1925 // different array object that happens to immediately follow the first array
1926 // object in the address space.)
1927 //
1928 // C11's version is more restrictive, however there's no reason why an argument
1929 // couldn't be a one-past-the-end value for a stack object in the caller and be
1930 // equal to the beginning of a stack object in the callee.
1931 //
1932 // If the C and C++ standards are ever made sufficiently restrictive in this
1933 // area, it may be possible to update LLVM's semantics accordingly and reinstate
1934 // this optimization.
computePointerICmp(const DataLayout * DL,const TargetLibraryInfo * TLI,CmpInst::Predicate Pred,Value * LHS,Value * RHS)1935 static Constant *computePointerICmp(const DataLayout *DL,
1936 const TargetLibraryInfo *TLI,
1937 CmpInst::Predicate Pred,
1938 Value *LHS, Value *RHS) {
1939 // First, skip past any trivial no-ops.
1940 LHS = LHS->stripPointerCasts();
1941 RHS = RHS->stripPointerCasts();
1942
1943 // A non-null pointer is not equal to a null pointer.
1944 if (llvm::isKnownNonNull(LHS, TLI) && isa<ConstantPointerNull>(RHS) &&
1945 (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE))
1946 return ConstantInt::get(GetCompareTy(LHS),
1947 !CmpInst::isTrueWhenEqual(Pred));
1948
1949 // We can only fold certain predicates on pointer comparisons.
1950 switch (Pred) {
1951 default:
1952 return nullptr;
1953
1954 // Equality comaprisons are easy to fold.
1955 case CmpInst::ICMP_EQ:
1956 case CmpInst::ICMP_NE:
1957 break;
1958
1959 // We can only handle unsigned relational comparisons because 'inbounds' on
1960 // a GEP only protects against unsigned wrapping.
1961 case CmpInst::ICMP_UGT:
1962 case CmpInst::ICMP_UGE:
1963 case CmpInst::ICMP_ULT:
1964 case CmpInst::ICMP_ULE:
1965 // However, we have to switch them to their signed variants to handle
1966 // negative indices from the base pointer.
1967 Pred = ICmpInst::getSignedPredicate(Pred);
1968 break;
1969 }
1970
1971 // Strip off any constant offsets so that we can reason about them.
1972 // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
1973 // here and compare base addresses like AliasAnalysis does, however there are
1974 // numerous hazards. AliasAnalysis and its utilities rely on special rules
1975 // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
1976 // doesn't need to guarantee pointer inequality when it says NoAlias.
1977 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
1978 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
1979
1980 // If LHS and RHS are related via constant offsets to the same base
1981 // value, we can replace it with an icmp which just compares the offsets.
1982 if (LHS == RHS)
1983 return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
1984
1985 // Various optimizations for (in)equality comparisons.
1986 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
1987 // Different non-empty allocations that exist at the same time have
1988 // different addresses (if the program can tell). Global variables always
1989 // exist, so they always exist during the lifetime of each other and all
1990 // allocas. Two different allocas usually have different addresses...
1991 //
1992 // However, if there's an @llvm.stackrestore dynamically in between two
1993 // allocas, they may have the same address. It's tempting to reduce the
1994 // scope of the problem by only looking at *static* allocas here. That would
1995 // cover the majority of allocas while significantly reducing the likelihood
1996 // of having an @llvm.stackrestore pop up in the middle. However, it's not
1997 // actually impossible for an @llvm.stackrestore to pop up in the middle of
1998 // an entry block. Also, if we have a block that's not attached to a
1999 // function, we can't tell if it's "static" under the current definition.
2000 // Theoretically, this problem could be fixed by creating a new kind of
2001 // instruction kind specifically for static allocas. Such a new instruction
2002 // could be required to be at the top of the entry block, thus preventing it
2003 // from being subject to a @llvm.stackrestore. Instcombine could even
2004 // convert regular allocas into these special allocas. It'd be nifty.
2005 // However, until then, this problem remains open.
2006 //
2007 // So, we'll assume that two non-empty allocas have different addresses
2008 // for now.
2009 //
2010 // With all that, if the offsets are within the bounds of their allocations
2011 // (and not one-past-the-end! so we can't use inbounds!), and their
2012 // allocations aren't the same, the pointers are not equal.
2013 //
2014 // Note that it's not necessary to check for LHS being a global variable
2015 // address, due to canonicalization and constant folding.
2016 if (isa<AllocaInst>(LHS) &&
2017 (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
2018 ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
2019 ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
2020 uint64_t LHSSize, RHSSize;
2021 if (LHSOffsetCI && RHSOffsetCI &&
2022 getObjectSize(LHS, LHSSize, DL, TLI) &&
2023 getObjectSize(RHS, RHSSize, DL, TLI)) {
2024 const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
2025 const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
2026 if (!LHSOffsetValue.isNegative() &&
2027 !RHSOffsetValue.isNegative() &&
2028 LHSOffsetValue.ult(LHSSize) &&
2029 RHSOffsetValue.ult(RHSSize)) {
2030 return ConstantInt::get(GetCompareTy(LHS),
2031 !CmpInst::isTrueWhenEqual(Pred));
2032 }
2033 }
2034
2035 // Repeat the above check but this time without depending on DataLayout
2036 // or being able to compute a precise size.
2037 if (!cast<PointerType>(LHS->getType())->isEmptyTy() &&
2038 !cast<PointerType>(RHS->getType())->isEmptyTy() &&
2039 LHSOffset->isNullValue() &&
2040 RHSOffset->isNullValue())
2041 return ConstantInt::get(GetCompareTy(LHS),
2042 !CmpInst::isTrueWhenEqual(Pred));
2043 }
2044
2045 // Even if an non-inbounds GEP occurs along the path we can still optimize
2046 // equality comparisons concerning the result. We avoid walking the whole
2047 // chain again by starting where the last calls to
2048 // stripAndComputeConstantOffsets left off and accumulate the offsets.
2049 Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true);
2050 Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true);
2051 if (LHS == RHS)
2052 return ConstantExpr::getICmp(Pred,
2053 ConstantExpr::getAdd(LHSOffset, LHSNoBound),
2054 ConstantExpr::getAdd(RHSOffset, RHSNoBound));
2055
2056 // If one side of the equality comparison must come from a noalias call
2057 // (meaning a system memory allocation function), and the other side must
2058 // come from a pointer that cannot overlap with dynamically-allocated
2059 // memory within the lifetime of the current function (allocas, byval
2060 // arguments, globals), then determine the comparison result here.
2061 SmallVector<Value *, 8> LHSUObjs, RHSUObjs;
2062 GetUnderlyingObjects(LHS, LHSUObjs, DL);
2063 GetUnderlyingObjects(RHS, RHSUObjs, DL);
2064
2065 // Is the set of underlying objects all noalias calls?
2066 auto IsNAC = [](SmallVectorImpl<Value *> &Objects) {
2067 return std::all_of(Objects.begin(), Objects.end(),
2068 [](Value *V){ return isNoAliasCall(V); });
2069 };
2070
2071 // Is the set of underlying objects all things which must be disjoint from
2072 // noalias calls. For allocas, we consider only static ones (dynamic
2073 // allocas might be transformed into calls to malloc not simultaneously
2074 // live with the compared-to allocation). For globals, we exclude symbols
2075 // that might be resolve lazily to symbols in another dynamically-loaded
2076 // library (and, thus, could be malloc'ed by the implementation).
2077 auto IsAllocDisjoint = [](SmallVectorImpl<Value *> &Objects) {
2078 return std::all_of(Objects.begin(), Objects.end(),
2079 [](Value *V){
2080 if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
2081 return AI->getParent() && AI->getParent()->getParent() &&
2082 AI->isStaticAlloca();
2083 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
2084 return (GV->hasLocalLinkage() ||
2085 GV->hasHiddenVisibility() ||
2086 GV->hasProtectedVisibility() ||
2087 GV->hasUnnamedAddr()) &&
2088 !GV->isThreadLocal();
2089 if (const Argument *A = dyn_cast<Argument>(V))
2090 return A->hasByValAttr();
2091 return false;
2092 });
2093 };
2094
2095 if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
2096 (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
2097 return ConstantInt::get(GetCompareTy(LHS),
2098 !CmpInst::isTrueWhenEqual(Pred));
2099 }
2100
2101 // Otherwise, fail.
2102 return nullptr;
2103 }
2104
2105 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
2106 /// fold the result. If not, this returns null.
SimplifyICmpInst(unsigned Predicate,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)2107 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2108 const Query &Q, unsigned MaxRecurse) {
2109 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2110 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
2111
2112 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2113 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2114 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
2115
2116 // If we have a constant, make sure it is on the RHS.
2117 std::swap(LHS, RHS);
2118 Pred = CmpInst::getSwappedPredicate(Pred);
2119 }
2120
2121 Type *ITy = GetCompareTy(LHS); // The return type.
2122 Type *OpTy = LHS->getType(); // The operand type.
2123
2124 // icmp X, X -> true/false
2125 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
2126 // because X could be 0.
2127 if (LHS == RHS || isa<UndefValue>(RHS))
2128 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
2129
2130 // Special case logic when the operands have i1 type.
2131 if (OpTy->getScalarType()->isIntegerTy(1)) {
2132 switch (Pred) {
2133 default: break;
2134 case ICmpInst::ICMP_EQ:
2135 // X == 1 -> X
2136 if (match(RHS, m_One()))
2137 return LHS;
2138 break;
2139 case ICmpInst::ICMP_NE:
2140 // X != 0 -> X
2141 if (match(RHS, m_Zero()))
2142 return LHS;
2143 break;
2144 case ICmpInst::ICMP_UGT:
2145 // X >u 0 -> X
2146 if (match(RHS, m_Zero()))
2147 return LHS;
2148 break;
2149 case ICmpInst::ICMP_UGE:
2150 // X >=u 1 -> X
2151 if (match(RHS, m_One()))
2152 return LHS;
2153 break;
2154 case ICmpInst::ICMP_SLT:
2155 // X <s 0 -> X
2156 if (match(RHS, m_Zero()))
2157 return LHS;
2158 break;
2159 case ICmpInst::ICMP_SLE:
2160 // X <=s -1 -> X
2161 if (match(RHS, m_One()))
2162 return LHS;
2163 break;
2164 }
2165 }
2166
2167 // If we are comparing with zero then try hard since this is a common case.
2168 if (match(RHS, m_Zero())) {
2169 bool LHSKnownNonNegative, LHSKnownNegative;
2170 switch (Pred) {
2171 default: llvm_unreachable("Unknown ICmp predicate!");
2172 case ICmpInst::ICMP_ULT:
2173 return getFalse(ITy);
2174 case ICmpInst::ICMP_UGE:
2175 return getTrue(ITy);
2176 case ICmpInst::ICMP_EQ:
2177 case ICmpInst::ICMP_ULE:
2178 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2179 return getFalse(ITy);
2180 break;
2181 case ICmpInst::ICMP_NE:
2182 case ICmpInst::ICMP_UGT:
2183 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2184 return getTrue(ITy);
2185 break;
2186 case ICmpInst::ICMP_SLT:
2187 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2188 Q.CxtI, Q.DT);
2189 if (LHSKnownNegative)
2190 return getTrue(ITy);
2191 if (LHSKnownNonNegative)
2192 return getFalse(ITy);
2193 break;
2194 case ICmpInst::ICMP_SLE:
2195 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2196 Q.CxtI, Q.DT);
2197 if (LHSKnownNegative)
2198 return getTrue(ITy);
2199 if (LHSKnownNonNegative &&
2200 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2201 return getFalse(ITy);
2202 break;
2203 case ICmpInst::ICMP_SGE:
2204 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2205 Q.CxtI, Q.DT);
2206 if (LHSKnownNegative)
2207 return getFalse(ITy);
2208 if (LHSKnownNonNegative)
2209 return getTrue(ITy);
2210 break;
2211 case ICmpInst::ICMP_SGT:
2212 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2213 Q.CxtI, Q.DT);
2214 if (LHSKnownNegative)
2215 return getFalse(ITy);
2216 if (LHSKnownNonNegative &&
2217 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2218 return getTrue(ITy);
2219 break;
2220 }
2221 }
2222
2223 // See if we are doing a comparison with a constant integer.
2224 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2225 // Rule out tautological comparisons (eg., ult 0 or uge 0).
2226 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
2227 if (RHS_CR.isEmptySet())
2228 return ConstantInt::getFalse(CI->getContext());
2229 if (RHS_CR.isFullSet())
2230 return ConstantInt::getTrue(CI->getContext());
2231
2232 // Many binary operators with constant RHS have easy to compute constant
2233 // range. Use them to check whether the comparison is a tautology.
2234 unsigned Width = CI->getBitWidth();
2235 APInt Lower = APInt(Width, 0);
2236 APInt Upper = APInt(Width, 0);
2237 ConstantInt *CI2;
2238 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
2239 // 'urem x, CI2' produces [0, CI2).
2240 Upper = CI2->getValue();
2241 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
2242 // 'srem x, CI2' produces (-|CI2|, |CI2|).
2243 Upper = CI2->getValue().abs();
2244 Lower = (-Upper) + 1;
2245 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
2246 // 'udiv CI2, x' produces [0, CI2].
2247 Upper = CI2->getValue() + 1;
2248 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
2249 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
2250 APInt NegOne = APInt::getAllOnesValue(Width);
2251 if (!CI2->isZero())
2252 Upper = NegOne.udiv(CI2->getValue()) + 1;
2253 } else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) {
2254 if (CI2->isMinSignedValue()) {
2255 // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
2256 Lower = CI2->getValue();
2257 Upper = Lower.lshr(1) + 1;
2258 } else {
2259 // 'sdiv CI2, x' produces [-|CI2|, |CI2|].
2260 Upper = CI2->getValue().abs() + 1;
2261 Lower = (-Upper) + 1;
2262 }
2263 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
2264 APInt IntMin = APInt::getSignedMinValue(Width);
2265 APInt IntMax = APInt::getSignedMaxValue(Width);
2266 APInt Val = CI2->getValue();
2267 if (Val.isAllOnesValue()) {
2268 // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
2269 // where CI2 != -1 and CI2 != 0 and CI2 != 1
2270 Lower = IntMin + 1;
2271 Upper = IntMax + 1;
2272 } else if (Val.countLeadingZeros() < Width - 1) {
2273 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]
2274 // where CI2 != -1 and CI2 != 0 and CI2 != 1
2275 Lower = IntMin.sdiv(Val);
2276 Upper = IntMax.sdiv(Val);
2277 if (Lower.sgt(Upper))
2278 std::swap(Lower, Upper);
2279 Upper = Upper + 1;
2280 assert(Upper != Lower && "Upper part of range has wrapped!");
2281 }
2282 } else if (match(LHS, m_NUWShl(m_ConstantInt(CI2), m_Value()))) {
2283 // 'shl nuw CI2, x' produces [CI2, CI2 << CLZ(CI2)]
2284 Lower = CI2->getValue();
2285 Upper = Lower.shl(Lower.countLeadingZeros()) + 1;
2286 } else if (match(LHS, m_NSWShl(m_ConstantInt(CI2), m_Value()))) {
2287 if (CI2->isNegative()) {
2288 // 'shl nsw CI2, x' produces [CI2 << CLO(CI2)-1, CI2]
2289 unsigned ShiftAmount = CI2->getValue().countLeadingOnes() - 1;
2290 Lower = CI2->getValue().shl(ShiftAmount);
2291 Upper = CI2->getValue() + 1;
2292 } else {
2293 // 'shl nsw CI2, x' produces [CI2, CI2 << CLZ(CI2)-1]
2294 unsigned ShiftAmount = CI2->getValue().countLeadingZeros() - 1;
2295 Lower = CI2->getValue();
2296 Upper = CI2->getValue().shl(ShiftAmount) + 1;
2297 }
2298 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
2299 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
2300 APInt NegOne = APInt::getAllOnesValue(Width);
2301 if (CI2->getValue().ult(Width))
2302 Upper = NegOne.lshr(CI2->getValue()) + 1;
2303 } else if (match(LHS, m_LShr(m_ConstantInt(CI2), m_Value()))) {
2304 // 'lshr CI2, x' produces [CI2 >> (Width-1), CI2].
2305 unsigned ShiftAmount = Width - 1;
2306 if (!CI2->isZero() && cast<BinaryOperator>(LHS)->isExact())
2307 ShiftAmount = CI2->getValue().countTrailingZeros();
2308 Lower = CI2->getValue().lshr(ShiftAmount);
2309 Upper = CI2->getValue() + 1;
2310 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
2311 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
2312 APInt IntMin = APInt::getSignedMinValue(Width);
2313 APInt IntMax = APInt::getSignedMaxValue(Width);
2314 if (CI2->getValue().ult(Width)) {
2315 Lower = IntMin.ashr(CI2->getValue());
2316 Upper = IntMax.ashr(CI2->getValue()) + 1;
2317 }
2318 } else if (match(LHS, m_AShr(m_ConstantInt(CI2), m_Value()))) {
2319 unsigned ShiftAmount = Width - 1;
2320 if (!CI2->isZero() && cast<BinaryOperator>(LHS)->isExact())
2321 ShiftAmount = CI2->getValue().countTrailingZeros();
2322 if (CI2->isNegative()) {
2323 // 'ashr CI2, x' produces [CI2, CI2 >> (Width-1)]
2324 Lower = CI2->getValue();
2325 Upper = CI2->getValue().ashr(ShiftAmount) + 1;
2326 } else {
2327 // 'ashr CI2, x' produces [CI2 >> (Width-1), CI2]
2328 Lower = CI2->getValue().ashr(ShiftAmount);
2329 Upper = CI2->getValue() + 1;
2330 }
2331 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
2332 // 'or x, CI2' produces [CI2, UINT_MAX].
2333 Lower = CI2->getValue();
2334 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
2335 // 'and x, CI2' produces [0, CI2].
2336 Upper = CI2->getValue() + 1;
2337 }
2338 if (Lower != Upper) {
2339 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
2340 if (RHS_CR.contains(LHS_CR))
2341 return ConstantInt::getTrue(RHS->getContext());
2342 if (RHS_CR.inverse().contains(LHS_CR))
2343 return ConstantInt::getFalse(RHS->getContext());
2344 }
2345 }
2346
2347 // Compare of cast, for example (zext X) != 0 -> X != 0
2348 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
2349 Instruction *LI = cast<CastInst>(LHS);
2350 Value *SrcOp = LI->getOperand(0);
2351 Type *SrcTy = SrcOp->getType();
2352 Type *DstTy = LI->getType();
2353
2354 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
2355 // if the integer type is the same size as the pointer type.
2356 if (MaxRecurse && Q.DL && isa<PtrToIntInst>(LI) &&
2357 Q.DL->getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
2358 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2359 // Transfer the cast to the constant.
2360 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
2361 ConstantExpr::getIntToPtr(RHSC, SrcTy),
2362 Q, MaxRecurse-1))
2363 return V;
2364 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
2365 if (RI->getOperand(0)->getType() == SrcTy)
2366 // Compare without the cast.
2367 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
2368 Q, MaxRecurse-1))
2369 return V;
2370 }
2371 }
2372
2373 if (isa<ZExtInst>(LHS)) {
2374 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
2375 // same type.
2376 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
2377 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
2378 // Compare X and Y. Note that signed predicates become unsigned.
2379 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
2380 SrcOp, RI->getOperand(0), Q,
2381 MaxRecurse-1))
2382 return V;
2383 }
2384 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
2385 // too. If not, then try to deduce the result of the comparison.
2386 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2387 // Compute the constant that would happen if we truncated to SrcTy then
2388 // reextended to DstTy.
2389 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
2390 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
2391
2392 // If the re-extended constant didn't change then this is effectively
2393 // also a case of comparing two zero-extended values.
2394 if (RExt == CI && MaxRecurse)
2395 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
2396 SrcOp, Trunc, Q, MaxRecurse-1))
2397 return V;
2398
2399 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
2400 // there. Use this to work out the result of the comparison.
2401 if (RExt != CI) {
2402 switch (Pred) {
2403 default: llvm_unreachable("Unknown ICmp predicate!");
2404 // LHS <u RHS.
2405 case ICmpInst::ICMP_EQ:
2406 case ICmpInst::ICMP_UGT:
2407 case ICmpInst::ICMP_UGE:
2408 return ConstantInt::getFalse(CI->getContext());
2409
2410 case ICmpInst::ICMP_NE:
2411 case ICmpInst::ICMP_ULT:
2412 case ICmpInst::ICMP_ULE:
2413 return ConstantInt::getTrue(CI->getContext());
2414
2415 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
2416 // is non-negative then LHS <s RHS.
2417 case ICmpInst::ICMP_SGT:
2418 case ICmpInst::ICMP_SGE:
2419 return CI->getValue().isNegative() ?
2420 ConstantInt::getTrue(CI->getContext()) :
2421 ConstantInt::getFalse(CI->getContext());
2422
2423 case ICmpInst::ICMP_SLT:
2424 case ICmpInst::ICMP_SLE:
2425 return CI->getValue().isNegative() ?
2426 ConstantInt::getFalse(CI->getContext()) :
2427 ConstantInt::getTrue(CI->getContext());
2428 }
2429 }
2430 }
2431 }
2432
2433 if (isa<SExtInst>(LHS)) {
2434 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
2435 // same type.
2436 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
2437 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
2438 // Compare X and Y. Note that the predicate does not change.
2439 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
2440 Q, MaxRecurse-1))
2441 return V;
2442 }
2443 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
2444 // too. If not, then try to deduce the result of the comparison.
2445 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2446 // Compute the constant that would happen if we truncated to SrcTy then
2447 // reextended to DstTy.
2448 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
2449 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
2450
2451 // If the re-extended constant didn't change then this is effectively
2452 // also a case of comparing two sign-extended values.
2453 if (RExt == CI && MaxRecurse)
2454 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
2455 return V;
2456
2457 // Otherwise the upper bits of LHS are all equal, while RHS has varying
2458 // bits there. Use this to work out the result of the comparison.
2459 if (RExt != CI) {
2460 switch (Pred) {
2461 default: llvm_unreachable("Unknown ICmp predicate!");
2462 case ICmpInst::ICMP_EQ:
2463 return ConstantInt::getFalse(CI->getContext());
2464 case ICmpInst::ICMP_NE:
2465 return ConstantInt::getTrue(CI->getContext());
2466
2467 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
2468 // LHS >s RHS.
2469 case ICmpInst::ICMP_SGT:
2470 case ICmpInst::ICMP_SGE:
2471 return CI->getValue().isNegative() ?
2472 ConstantInt::getTrue(CI->getContext()) :
2473 ConstantInt::getFalse(CI->getContext());
2474 case ICmpInst::ICMP_SLT:
2475 case ICmpInst::ICMP_SLE:
2476 return CI->getValue().isNegative() ?
2477 ConstantInt::getFalse(CI->getContext()) :
2478 ConstantInt::getTrue(CI->getContext());
2479
2480 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
2481 // LHS >u RHS.
2482 case ICmpInst::ICMP_UGT:
2483 case ICmpInst::ICMP_UGE:
2484 // Comparison is true iff the LHS <s 0.
2485 if (MaxRecurse)
2486 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
2487 Constant::getNullValue(SrcTy),
2488 Q, MaxRecurse-1))
2489 return V;
2490 break;
2491 case ICmpInst::ICMP_ULT:
2492 case ICmpInst::ICMP_ULE:
2493 // Comparison is true iff the LHS >=s 0.
2494 if (MaxRecurse)
2495 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
2496 Constant::getNullValue(SrcTy),
2497 Q, MaxRecurse-1))
2498 return V;
2499 break;
2500 }
2501 }
2502 }
2503 }
2504 }
2505
2506 // Special logic for binary operators.
2507 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2508 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2509 if (MaxRecurse && (LBO || RBO)) {
2510 // Analyze the case when either LHS or RHS is an add instruction.
2511 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2512 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2513 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2514 if (LBO && LBO->getOpcode() == Instruction::Add) {
2515 A = LBO->getOperand(0); B = LBO->getOperand(1);
2516 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
2517 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
2518 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
2519 }
2520 if (RBO && RBO->getOpcode() == Instruction::Add) {
2521 C = RBO->getOperand(0); D = RBO->getOperand(1);
2522 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
2523 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2524 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2525 }
2526
2527 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2528 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2529 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2530 Constant::getNullValue(RHS->getType()),
2531 Q, MaxRecurse-1))
2532 return V;
2533
2534 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2535 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2536 if (Value *V = SimplifyICmpInst(Pred,
2537 Constant::getNullValue(LHS->getType()),
2538 C == LHS ? D : C, Q, MaxRecurse-1))
2539 return V;
2540
2541 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2542 if (A && C && (A == C || A == D || B == C || B == D) &&
2543 NoLHSWrapProblem && NoRHSWrapProblem) {
2544 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2545 Value *Y, *Z;
2546 if (A == C) {
2547 // C + B == C + D -> B == D
2548 Y = B;
2549 Z = D;
2550 } else if (A == D) {
2551 // D + B == C + D -> B == C
2552 Y = B;
2553 Z = C;
2554 } else if (B == C) {
2555 // A + C == C + D -> A == D
2556 Y = A;
2557 Z = D;
2558 } else {
2559 assert(B == D);
2560 // A + D == C + D -> A == C
2561 Y = A;
2562 Z = C;
2563 }
2564 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
2565 return V;
2566 }
2567 }
2568
2569 // icmp pred (or X, Y), X
2570 if (LBO && match(LBO, m_CombineOr(m_Or(m_Value(), m_Specific(RHS)),
2571 m_Or(m_Specific(RHS), m_Value())))) {
2572 if (Pred == ICmpInst::ICMP_ULT)
2573 return getFalse(ITy);
2574 if (Pred == ICmpInst::ICMP_UGE)
2575 return getTrue(ITy);
2576 }
2577 // icmp pred X, (or X, Y)
2578 if (RBO && match(RBO, m_CombineOr(m_Or(m_Value(), m_Specific(LHS)),
2579 m_Or(m_Specific(LHS), m_Value())))) {
2580 if (Pred == ICmpInst::ICMP_ULE)
2581 return getTrue(ITy);
2582 if (Pred == ICmpInst::ICMP_UGT)
2583 return getFalse(ITy);
2584 }
2585
2586 // icmp pred (and X, Y), X
2587 if (LBO && match(LBO, m_CombineOr(m_And(m_Value(), m_Specific(RHS)),
2588 m_And(m_Specific(RHS), m_Value())))) {
2589 if (Pred == ICmpInst::ICMP_UGT)
2590 return getFalse(ITy);
2591 if (Pred == ICmpInst::ICMP_ULE)
2592 return getTrue(ITy);
2593 }
2594 // icmp pred X, (and X, Y)
2595 if (RBO && match(RBO, m_CombineOr(m_And(m_Value(), m_Specific(LHS)),
2596 m_And(m_Specific(LHS), m_Value())))) {
2597 if (Pred == ICmpInst::ICMP_UGE)
2598 return getTrue(ITy);
2599 if (Pred == ICmpInst::ICMP_ULT)
2600 return getFalse(ITy);
2601 }
2602
2603 // 0 - (zext X) pred C
2604 if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
2605 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
2606 if (RHSC->getValue().isStrictlyPositive()) {
2607 if (Pred == ICmpInst::ICMP_SLT)
2608 return ConstantInt::getTrue(RHSC->getContext());
2609 if (Pred == ICmpInst::ICMP_SGE)
2610 return ConstantInt::getFalse(RHSC->getContext());
2611 if (Pred == ICmpInst::ICMP_EQ)
2612 return ConstantInt::getFalse(RHSC->getContext());
2613 if (Pred == ICmpInst::ICMP_NE)
2614 return ConstantInt::getTrue(RHSC->getContext());
2615 }
2616 if (RHSC->getValue().isNonNegative()) {
2617 if (Pred == ICmpInst::ICMP_SLE)
2618 return ConstantInt::getTrue(RHSC->getContext());
2619 if (Pred == ICmpInst::ICMP_SGT)
2620 return ConstantInt::getFalse(RHSC->getContext());
2621 }
2622 }
2623 }
2624
2625 // icmp pred (urem X, Y), Y
2626 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2627 bool KnownNonNegative, KnownNegative;
2628 switch (Pred) {
2629 default:
2630 break;
2631 case ICmpInst::ICMP_SGT:
2632 case ICmpInst::ICMP_SGE:
2633 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2634 Q.CxtI, Q.DT);
2635 if (!KnownNonNegative)
2636 break;
2637 // fall-through
2638 case ICmpInst::ICMP_EQ:
2639 case ICmpInst::ICMP_UGT:
2640 case ICmpInst::ICMP_UGE:
2641 return getFalse(ITy);
2642 case ICmpInst::ICMP_SLT:
2643 case ICmpInst::ICMP_SLE:
2644 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2645 Q.CxtI, Q.DT);
2646 if (!KnownNonNegative)
2647 break;
2648 // fall-through
2649 case ICmpInst::ICMP_NE:
2650 case ICmpInst::ICMP_ULT:
2651 case ICmpInst::ICMP_ULE:
2652 return getTrue(ITy);
2653 }
2654 }
2655
2656 // icmp pred X, (urem Y, X)
2657 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2658 bool KnownNonNegative, KnownNegative;
2659 switch (Pred) {
2660 default:
2661 break;
2662 case ICmpInst::ICMP_SGT:
2663 case ICmpInst::ICMP_SGE:
2664 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2665 Q.CxtI, Q.DT);
2666 if (!KnownNonNegative)
2667 break;
2668 // fall-through
2669 case ICmpInst::ICMP_NE:
2670 case ICmpInst::ICMP_UGT:
2671 case ICmpInst::ICMP_UGE:
2672 return getTrue(ITy);
2673 case ICmpInst::ICMP_SLT:
2674 case ICmpInst::ICMP_SLE:
2675 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2676 Q.CxtI, Q.DT);
2677 if (!KnownNonNegative)
2678 break;
2679 // fall-through
2680 case ICmpInst::ICMP_EQ:
2681 case ICmpInst::ICMP_ULT:
2682 case ICmpInst::ICMP_ULE:
2683 return getFalse(ITy);
2684 }
2685 }
2686
2687 // x udiv y <=u x.
2688 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2689 // icmp pred (X /u Y), X
2690 if (Pred == ICmpInst::ICMP_UGT)
2691 return getFalse(ITy);
2692 if (Pred == ICmpInst::ICMP_ULE)
2693 return getTrue(ITy);
2694 }
2695
2696 // handle:
2697 // CI2 << X == CI
2698 // CI2 << X != CI
2699 //
2700 // where CI2 is a power of 2 and CI isn't
2701 if (auto *CI = dyn_cast<ConstantInt>(RHS)) {
2702 const APInt *CI2Val, *CIVal = &CI->getValue();
2703 if (LBO && match(LBO, m_Shl(m_APInt(CI2Val), m_Value())) &&
2704 CI2Val->isPowerOf2()) {
2705 if (!CIVal->isPowerOf2()) {
2706 // CI2 << X can equal zero in some circumstances,
2707 // this simplification is unsafe if CI is zero.
2708 //
2709 // We know it is safe if:
2710 // - The shift is nsw, we can't shift out the one bit.
2711 // - The shift is nuw, we can't shift out the one bit.
2712 // - CI2 is one
2713 // - CI isn't zero
2714 if (LBO->hasNoSignedWrap() || LBO->hasNoUnsignedWrap() ||
2715 *CI2Val == 1 || !CI->isZero()) {
2716 if (Pred == ICmpInst::ICMP_EQ)
2717 return ConstantInt::getFalse(RHS->getContext());
2718 if (Pred == ICmpInst::ICMP_NE)
2719 return ConstantInt::getTrue(RHS->getContext());
2720 }
2721 }
2722 if (CIVal->isSignBit() && *CI2Val == 1) {
2723 if (Pred == ICmpInst::ICMP_UGT)
2724 return ConstantInt::getFalse(RHS->getContext());
2725 if (Pred == ICmpInst::ICMP_ULE)
2726 return ConstantInt::getTrue(RHS->getContext());
2727 }
2728 }
2729 }
2730
2731 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2732 LBO->getOperand(1) == RBO->getOperand(1)) {
2733 switch (LBO->getOpcode()) {
2734 default: break;
2735 case Instruction::UDiv:
2736 case Instruction::LShr:
2737 if (ICmpInst::isSigned(Pred))
2738 break;
2739 // fall-through
2740 case Instruction::SDiv:
2741 case Instruction::AShr:
2742 if (!LBO->isExact() || !RBO->isExact())
2743 break;
2744 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2745 RBO->getOperand(0), Q, MaxRecurse-1))
2746 return V;
2747 break;
2748 case Instruction::Shl: {
2749 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2750 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2751 if (!NUW && !NSW)
2752 break;
2753 if (!NSW && ICmpInst::isSigned(Pred))
2754 break;
2755 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2756 RBO->getOperand(0), Q, MaxRecurse-1))
2757 return V;
2758 break;
2759 }
2760 }
2761 }
2762
2763 // Simplify comparisons involving max/min.
2764 Value *A, *B;
2765 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2766 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2767
2768 // Signed variants on "max(a,b)>=a -> true".
2769 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2770 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2771 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2772 // We analyze this as smax(A, B) pred A.
2773 P = Pred;
2774 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2775 (A == LHS || B == LHS)) {
2776 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2777 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2778 // We analyze this as smax(A, B) swapped-pred A.
2779 P = CmpInst::getSwappedPredicate(Pred);
2780 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2781 (A == RHS || B == RHS)) {
2782 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2783 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2784 // We analyze this as smax(-A, -B) swapped-pred -A.
2785 // Note that we do not need to actually form -A or -B thanks to EqP.
2786 P = CmpInst::getSwappedPredicate(Pred);
2787 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2788 (A == LHS || B == LHS)) {
2789 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2790 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2791 // We analyze this as smax(-A, -B) pred -A.
2792 // Note that we do not need to actually form -A or -B thanks to EqP.
2793 P = Pred;
2794 }
2795 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2796 // Cases correspond to "max(A, B) p A".
2797 switch (P) {
2798 default:
2799 break;
2800 case CmpInst::ICMP_EQ:
2801 case CmpInst::ICMP_SLE:
2802 // Equivalent to "A EqP B". This may be the same as the condition tested
2803 // in the max/min; if so, we can just return that.
2804 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2805 return V;
2806 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2807 return V;
2808 // Otherwise, see if "A EqP B" simplifies.
2809 if (MaxRecurse)
2810 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2811 return V;
2812 break;
2813 case CmpInst::ICMP_NE:
2814 case CmpInst::ICMP_SGT: {
2815 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2816 // Equivalent to "A InvEqP B". This may be the same as the condition
2817 // tested in the max/min; if so, we can just return that.
2818 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2819 return V;
2820 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2821 return V;
2822 // Otherwise, see if "A InvEqP B" simplifies.
2823 if (MaxRecurse)
2824 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2825 return V;
2826 break;
2827 }
2828 case CmpInst::ICMP_SGE:
2829 // Always true.
2830 return getTrue(ITy);
2831 case CmpInst::ICMP_SLT:
2832 // Always false.
2833 return getFalse(ITy);
2834 }
2835 }
2836
2837 // Unsigned variants on "max(a,b)>=a -> true".
2838 P = CmpInst::BAD_ICMP_PREDICATE;
2839 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2840 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2841 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2842 // We analyze this as umax(A, B) pred A.
2843 P = Pred;
2844 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2845 (A == LHS || B == LHS)) {
2846 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2847 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2848 // We analyze this as umax(A, B) swapped-pred A.
2849 P = CmpInst::getSwappedPredicate(Pred);
2850 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2851 (A == RHS || B == RHS)) {
2852 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2853 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2854 // We analyze this as umax(-A, -B) swapped-pred -A.
2855 // Note that we do not need to actually form -A or -B thanks to EqP.
2856 P = CmpInst::getSwappedPredicate(Pred);
2857 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2858 (A == LHS || B == LHS)) {
2859 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2860 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2861 // We analyze this as umax(-A, -B) pred -A.
2862 // Note that we do not need to actually form -A or -B thanks to EqP.
2863 P = Pred;
2864 }
2865 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2866 // Cases correspond to "max(A, B) p A".
2867 switch (P) {
2868 default:
2869 break;
2870 case CmpInst::ICMP_EQ:
2871 case CmpInst::ICMP_ULE:
2872 // Equivalent to "A EqP B". This may be the same as the condition tested
2873 // in the max/min; if so, we can just return that.
2874 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2875 return V;
2876 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2877 return V;
2878 // Otherwise, see if "A EqP B" simplifies.
2879 if (MaxRecurse)
2880 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2881 return V;
2882 break;
2883 case CmpInst::ICMP_NE:
2884 case CmpInst::ICMP_UGT: {
2885 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2886 // Equivalent to "A InvEqP B". This may be the same as the condition
2887 // tested in the max/min; if so, we can just return that.
2888 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2889 return V;
2890 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2891 return V;
2892 // Otherwise, see if "A InvEqP B" simplifies.
2893 if (MaxRecurse)
2894 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2895 return V;
2896 break;
2897 }
2898 case CmpInst::ICMP_UGE:
2899 // Always true.
2900 return getTrue(ITy);
2901 case CmpInst::ICMP_ULT:
2902 // Always false.
2903 return getFalse(ITy);
2904 }
2905 }
2906
2907 // Variants on "max(x,y) >= min(x,z)".
2908 Value *C, *D;
2909 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2910 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2911 (A == C || A == D || B == C || B == D)) {
2912 // max(x, ?) pred min(x, ?).
2913 if (Pred == CmpInst::ICMP_SGE)
2914 // Always true.
2915 return getTrue(ITy);
2916 if (Pred == CmpInst::ICMP_SLT)
2917 // Always false.
2918 return getFalse(ITy);
2919 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2920 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2921 (A == C || A == D || B == C || B == D)) {
2922 // min(x, ?) pred max(x, ?).
2923 if (Pred == CmpInst::ICMP_SLE)
2924 // Always true.
2925 return getTrue(ITy);
2926 if (Pred == CmpInst::ICMP_SGT)
2927 // Always false.
2928 return getFalse(ITy);
2929 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2930 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2931 (A == C || A == D || B == C || B == D)) {
2932 // max(x, ?) pred min(x, ?).
2933 if (Pred == CmpInst::ICMP_UGE)
2934 // Always true.
2935 return getTrue(ITy);
2936 if (Pred == CmpInst::ICMP_ULT)
2937 // Always false.
2938 return getFalse(ITy);
2939 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2940 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2941 (A == C || A == D || B == C || B == D)) {
2942 // min(x, ?) pred max(x, ?).
2943 if (Pred == CmpInst::ICMP_ULE)
2944 // Always true.
2945 return getTrue(ITy);
2946 if (Pred == CmpInst::ICMP_UGT)
2947 // Always false.
2948 return getFalse(ITy);
2949 }
2950
2951 // Simplify comparisons of related pointers using a powerful, recursive
2952 // GEP-walk when we have target data available..
2953 if (LHS->getType()->isPointerTy())
2954 if (Constant *C = computePointerICmp(Q.DL, Q.TLI, Pred, LHS, RHS))
2955 return C;
2956
2957 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
2958 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
2959 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
2960 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
2961 (ICmpInst::isEquality(Pred) ||
2962 (GLHS->isInBounds() && GRHS->isInBounds() &&
2963 Pred == ICmpInst::getSignedPredicate(Pred)))) {
2964 // The bases are equal and the indices are constant. Build a constant
2965 // expression GEP with the same indices and a null base pointer to see
2966 // what constant folding can make out of it.
2967 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
2968 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
2969 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS);
2970
2971 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
2972 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS);
2973 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
2974 }
2975 }
2976 }
2977
2978 // If a bit is known to be zero for A and known to be one for B,
2979 // then A and B cannot be equal.
2980 if (ICmpInst::isEquality(Pred)) {
2981 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
2982 uint32_t BitWidth = CI->getBitWidth();
2983 APInt LHSKnownZero(BitWidth, 0);
2984 APInt LHSKnownOne(BitWidth, 0);
2985 computeKnownBits(LHS, LHSKnownZero, LHSKnownOne, Q.DL, /*Depth=*/0, Q.AC,
2986 Q.CxtI, Q.DT);
2987 const APInt &RHSVal = CI->getValue();
2988 if (((LHSKnownZero & RHSVal) != 0) || ((LHSKnownOne & ~RHSVal) != 0))
2989 return Pred == ICmpInst::ICMP_EQ
2990 ? ConstantInt::getFalse(CI->getContext())
2991 : ConstantInt::getTrue(CI->getContext());
2992 }
2993 }
2994
2995 // If the comparison is with the result of a select instruction, check whether
2996 // comparing with either branch of the select always yields the same value.
2997 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2998 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2999 return V;
3000
3001 // If the comparison is with the result of a phi instruction, check whether
3002 // doing the compare with each incoming phi value yields a common result.
3003 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3004 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3005 return V;
3006
3007 return nullptr;
3008 }
3009
SimplifyICmpInst(unsigned Predicate,Value * LHS,Value * RHS,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,Instruction * CxtI)3010 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3011 const DataLayout *DL,
3012 const TargetLibraryInfo *TLI,
3013 const DominatorTree *DT, AssumptionCache *AC,
3014 Instruction *CxtI) {
3015 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
3016 RecursionLimit);
3017 }
3018
3019 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
3020 /// fold the result. If not, this returns null.
SimplifyFCmpInst(unsigned Predicate,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)3021 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3022 const Query &Q, unsigned MaxRecurse) {
3023 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3024 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
3025
3026 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3027 if (Constant *CRHS = dyn_cast<Constant>(RHS))
3028 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3029
3030 // If we have a constant, make sure it is on the RHS.
3031 std::swap(LHS, RHS);
3032 Pred = CmpInst::getSwappedPredicate(Pred);
3033 }
3034
3035 // Fold trivial predicates.
3036 if (Pred == FCmpInst::FCMP_FALSE)
3037 return ConstantInt::get(GetCompareTy(LHS), 0);
3038 if (Pred == FCmpInst::FCMP_TRUE)
3039 return ConstantInt::get(GetCompareTy(LHS), 1);
3040
3041 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
3042 return UndefValue::get(GetCompareTy(LHS));
3043
3044 // fcmp x,x -> true/false. Not all compares are foldable.
3045 if (LHS == RHS) {
3046 if (CmpInst::isTrueWhenEqual(Pred))
3047 return ConstantInt::get(GetCompareTy(LHS), 1);
3048 if (CmpInst::isFalseWhenEqual(Pred))
3049 return ConstantInt::get(GetCompareTy(LHS), 0);
3050 }
3051
3052 // Handle fcmp with constant RHS
3053 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
3054 // If the constant is a nan, see if we can fold the comparison based on it.
3055 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
3056 if (CFP->getValueAPF().isNaN()) {
3057 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
3058 return ConstantInt::getFalse(CFP->getContext());
3059 assert(FCmpInst::isUnordered(Pred) &&
3060 "Comparison must be either ordered or unordered!");
3061 // True if unordered.
3062 return ConstantInt::getTrue(CFP->getContext());
3063 }
3064 // Check whether the constant is an infinity.
3065 if (CFP->getValueAPF().isInfinity()) {
3066 if (CFP->getValueAPF().isNegative()) {
3067 switch (Pred) {
3068 case FCmpInst::FCMP_OLT:
3069 // No value is ordered and less than negative infinity.
3070 return ConstantInt::getFalse(CFP->getContext());
3071 case FCmpInst::FCMP_UGE:
3072 // All values are unordered with or at least negative infinity.
3073 return ConstantInt::getTrue(CFP->getContext());
3074 default:
3075 break;
3076 }
3077 } else {
3078 switch (Pred) {
3079 case FCmpInst::FCMP_OGT:
3080 // No value is ordered and greater than infinity.
3081 return ConstantInt::getFalse(CFP->getContext());
3082 case FCmpInst::FCMP_ULE:
3083 // All values are unordered with and at most infinity.
3084 return ConstantInt::getTrue(CFP->getContext());
3085 default:
3086 break;
3087 }
3088 }
3089 }
3090 }
3091 }
3092
3093 // If the comparison is with the result of a select instruction, check whether
3094 // comparing with either branch of the select always yields the same value.
3095 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3096 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3097 return V;
3098
3099 // If the comparison is with the result of a phi instruction, check whether
3100 // doing the compare with each incoming phi value yields a common result.
3101 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3102 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3103 return V;
3104
3105 return nullptr;
3106 }
3107
SimplifyFCmpInst(unsigned Predicate,Value * LHS,Value * RHS,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3108 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3109 const DataLayout *DL,
3110 const TargetLibraryInfo *TLI,
3111 const DominatorTree *DT, AssumptionCache *AC,
3112 const Instruction *CxtI) {
3113 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
3114 RecursionLimit);
3115 }
3116
3117 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
3118 /// the result. If not, this returns null.
SimplifySelectInst(Value * CondVal,Value * TrueVal,Value * FalseVal,const Query & Q,unsigned MaxRecurse)3119 static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
3120 Value *FalseVal, const Query &Q,
3121 unsigned MaxRecurse) {
3122 // select true, X, Y -> X
3123 // select false, X, Y -> Y
3124 if (Constant *CB = dyn_cast<Constant>(CondVal)) {
3125 if (CB->isAllOnesValue())
3126 return TrueVal;
3127 if (CB->isNullValue())
3128 return FalseVal;
3129 }
3130
3131 // select C, X, X -> X
3132 if (TrueVal == FalseVal)
3133 return TrueVal;
3134
3135 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
3136 if (isa<Constant>(TrueVal))
3137 return TrueVal;
3138 return FalseVal;
3139 }
3140 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
3141 return FalseVal;
3142 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
3143 return TrueVal;
3144
3145 const auto *ICI = dyn_cast<ICmpInst>(CondVal);
3146 unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits();
3147 if (ICI && BitWidth) {
3148 ICmpInst::Predicate Pred = ICI->getPredicate();
3149 APInt MinSignedValue = APInt::getSignBit(BitWidth);
3150 Value *X;
3151 const APInt *Y;
3152 bool TrueWhenUnset;
3153 bool IsBitTest = false;
3154 if (ICmpInst::isEquality(Pred) &&
3155 match(ICI->getOperand(0), m_And(m_Value(X), m_APInt(Y))) &&
3156 match(ICI->getOperand(1), m_Zero())) {
3157 IsBitTest = true;
3158 TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
3159 } else if (Pred == ICmpInst::ICMP_SLT &&
3160 match(ICI->getOperand(1), m_Zero())) {
3161 X = ICI->getOperand(0);
3162 Y = &MinSignedValue;
3163 IsBitTest = true;
3164 TrueWhenUnset = false;
3165 } else if (Pred == ICmpInst::ICMP_SGT &&
3166 match(ICI->getOperand(1), m_AllOnes())) {
3167 X = ICI->getOperand(0);
3168 Y = &MinSignedValue;
3169 IsBitTest = true;
3170 TrueWhenUnset = true;
3171 }
3172 if (IsBitTest) {
3173 const APInt *C;
3174 // (X & Y) == 0 ? X & ~Y : X --> X
3175 // (X & Y) != 0 ? X & ~Y : X --> X & ~Y
3176 if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) &&
3177 *Y == ~*C)
3178 return TrueWhenUnset ? FalseVal : TrueVal;
3179 // (X & Y) == 0 ? X : X & ~Y --> X & ~Y
3180 // (X & Y) != 0 ? X : X & ~Y --> X
3181 if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) &&
3182 *Y == ~*C)
3183 return TrueWhenUnset ? FalseVal : TrueVal;
3184
3185 if (Y->isPowerOf2()) {
3186 // (X & Y) == 0 ? X | Y : X --> X | Y
3187 // (X & Y) != 0 ? X | Y : X --> X
3188 if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) &&
3189 *Y == *C)
3190 return TrueWhenUnset ? TrueVal : FalseVal;
3191 // (X & Y) == 0 ? X : X | Y --> X
3192 // (X & Y) != 0 ? X : X | Y --> X | Y
3193 if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) &&
3194 *Y == *C)
3195 return TrueWhenUnset ? TrueVal : FalseVal;
3196 }
3197 }
3198 }
3199
3200 return nullptr;
3201 }
3202
SimplifySelectInst(Value * Cond,Value * TrueVal,Value * FalseVal,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3203 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3204 const DataLayout *DL,
3205 const TargetLibraryInfo *TLI,
3206 const DominatorTree *DT, AssumptionCache *AC,
3207 const Instruction *CxtI) {
3208 return ::SimplifySelectInst(Cond, TrueVal, FalseVal,
3209 Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
3210 }
3211
3212 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
3213 /// fold the result. If not, this returns null.
SimplifyGEPInst(ArrayRef<Value * > Ops,const Query & Q,unsigned)3214 static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) {
3215 // The type of the GEP pointer operand.
3216 PointerType *PtrTy = cast<PointerType>(Ops[0]->getType()->getScalarType());
3217 unsigned AS = PtrTy->getAddressSpace();
3218
3219 // getelementptr P -> P.
3220 if (Ops.size() == 1)
3221 return Ops[0];
3222
3223 // Compute the (pointer) type returned by the GEP instruction.
3224 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
3225 Type *GEPTy = PointerType::get(LastType, AS);
3226 if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
3227 GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3228
3229 if (isa<UndefValue>(Ops[0]))
3230 return UndefValue::get(GEPTy);
3231
3232 if (Ops.size() == 2) {
3233 // getelementptr P, 0 -> P.
3234 if (match(Ops[1], m_Zero()))
3235 return Ops[0];
3236
3237 Type *Ty = PtrTy->getElementType();
3238 if (Q.DL && Ty->isSized()) {
3239 Value *P;
3240 uint64_t C;
3241 uint64_t TyAllocSize = Q.DL->getTypeAllocSize(Ty);
3242 // getelementptr P, N -> P if P points to a type of zero size.
3243 if (TyAllocSize == 0)
3244 return Ops[0];
3245
3246 // The following transforms are only safe if the ptrtoint cast
3247 // doesn't truncate the pointers.
3248 if (Ops[1]->getType()->getScalarSizeInBits() ==
3249 Q.DL->getPointerSizeInBits(AS)) {
3250 auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * {
3251 if (match(P, m_Zero()))
3252 return Constant::getNullValue(GEPTy);
3253 Value *Temp;
3254 if (match(P, m_PtrToInt(m_Value(Temp))))
3255 if (Temp->getType() == GEPTy)
3256 return Temp;
3257 return nullptr;
3258 };
3259
3260 // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
3261 if (TyAllocSize == 1 &&
3262 match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0])))))
3263 if (Value *R = PtrToIntOrZero(P))
3264 return R;
3265
3266 // getelementptr V, (ashr (sub P, V), C) -> Q
3267 // if P points to a type of size 1 << C.
3268 if (match(Ops[1],
3269 m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3270 m_ConstantInt(C))) &&
3271 TyAllocSize == 1ULL << C)
3272 if (Value *R = PtrToIntOrZero(P))
3273 return R;
3274
3275 // getelementptr V, (sdiv (sub P, V), C) -> Q
3276 // if P points to a type of size C.
3277 if (match(Ops[1],
3278 m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3279 m_SpecificInt(TyAllocSize))))
3280 if (Value *R = PtrToIntOrZero(P))
3281 return R;
3282 }
3283 }
3284 }
3285
3286 // Check to see if this is constant foldable.
3287 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3288 if (!isa<Constant>(Ops[i]))
3289 return nullptr;
3290
3291 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
3292 }
3293
SimplifyGEPInst(ArrayRef<Value * > Ops,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3294 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const DataLayout *DL,
3295 const TargetLibraryInfo *TLI,
3296 const DominatorTree *DT, AssumptionCache *AC,
3297 const Instruction *CxtI) {
3298 return ::SimplifyGEPInst(Ops, Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
3299 }
3300
3301 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
3302 /// can fold the result. If not, this returns null.
SimplifyInsertValueInst(Value * Agg,Value * Val,ArrayRef<unsigned> Idxs,const Query & Q,unsigned)3303 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
3304 ArrayRef<unsigned> Idxs, const Query &Q,
3305 unsigned) {
3306 if (Constant *CAgg = dyn_cast<Constant>(Agg))
3307 if (Constant *CVal = dyn_cast<Constant>(Val))
3308 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
3309
3310 // insertvalue x, undef, n -> x
3311 if (match(Val, m_Undef()))
3312 return Agg;
3313
3314 // insertvalue x, (extractvalue y, n), n
3315 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
3316 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
3317 EV->getIndices() == Idxs) {
3318 // insertvalue undef, (extractvalue y, n), n -> y
3319 if (match(Agg, m_Undef()))
3320 return EV->getAggregateOperand();
3321
3322 // insertvalue y, (extractvalue y, n), n -> y
3323 if (Agg == EV->getAggregateOperand())
3324 return Agg;
3325 }
3326
3327 return nullptr;
3328 }
3329
SimplifyInsertValueInst(Value * Agg,Value * Val,ArrayRef<unsigned> Idxs,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3330 Value *llvm::SimplifyInsertValueInst(
3331 Value *Agg, Value *Val, ArrayRef<unsigned> Idxs, const DataLayout *DL,
3332 const TargetLibraryInfo *TLI, const DominatorTree *DT, AssumptionCache *AC,
3333 const Instruction *CxtI) {
3334 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query(DL, TLI, DT, AC, CxtI),
3335 RecursionLimit);
3336 }
3337
3338 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
SimplifyPHINode(PHINode * PN,const Query & Q)3339 static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
3340 // If all of the PHI's incoming values are the same then replace the PHI node
3341 // with the common value.
3342 Value *CommonValue = nullptr;
3343 bool HasUndefInput = false;
3344 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
3345 Value *Incoming = PN->getIncomingValue(i);
3346 // If the incoming value is the phi node itself, it can safely be skipped.
3347 if (Incoming == PN) continue;
3348 if (isa<UndefValue>(Incoming)) {
3349 // Remember that we saw an undef value, but otherwise ignore them.
3350 HasUndefInput = true;
3351 continue;
3352 }
3353 if (CommonValue && Incoming != CommonValue)
3354 return nullptr; // Not the same, bail out.
3355 CommonValue = Incoming;
3356 }
3357
3358 // If CommonValue is null then all of the incoming values were either undef or
3359 // equal to the phi node itself.
3360 if (!CommonValue)
3361 return UndefValue::get(PN->getType());
3362
3363 // If we have a PHI node like phi(X, undef, X), where X is defined by some
3364 // instruction, we cannot return X as the result of the PHI node unless it
3365 // dominates the PHI block.
3366 if (HasUndefInput)
3367 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr;
3368
3369 return CommonValue;
3370 }
3371
SimplifyTruncInst(Value * Op,Type * Ty,const Query & Q,unsigned)3372 static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) {
3373 if (Constant *C = dyn_cast<Constant>(Op))
3374 return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.DL, Q.TLI);
3375
3376 return nullptr;
3377 }
3378
SimplifyTruncInst(Value * Op,Type * Ty,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3379 Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const DataLayout *DL,
3380 const TargetLibraryInfo *TLI,
3381 const DominatorTree *DT, AssumptionCache *AC,
3382 const Instruction *CxtI) {
3383 return ::SimplifyTruncInst(Op, Ty, Query(DL, TLI, DT, AC, CxtI),
3384 RecursionLimit);
3385 }
3386
3387 //=== Helper functions for higher up the class hierarchy.
3388
3389 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
3390 /// fold the result. If not, this returns null.
SimplifyBinOp(unsigned Opcode,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)3391 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
3392 const Query &Q, unsigned MaxRecurse) {
3393 switch (Opcode) {
3394 case Instruction::Add:
3395 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3396 Q, MaxRecurse);
3397 case Instruction::FAdd:
3398 return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3399
3400 case Instruction::Sub:
3401 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3402 Q, MaxRecurse);
3403 case Instruction::FSub:
3404 return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3405
3406 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
3407 case Instruction::FMul:
3408 return SimplifyFMulInst (LHS, RHS, FastMathFlags(), Q, MaxRecurse);
3409 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
3410 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
3411 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse);
3412 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
3413 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
3414 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse);
3415 case Instruction::Shl:
3416 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
3417 Q, MaxRecurse);
3418 case Instruction::LShr:
3419 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
3420 case Instruction::AShr:
3421 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
3422 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
3423 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
3424 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
3425 default:
3426 if (Constant *CLHS = dyn_cast<Constant>(LHS))
3427 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
3428 Constant *COps[] = {CLHS, CRHS};
3429 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.DL,
3430 Q.TLI);
3431 }
3432
3433 // If the operation is associative, try some generic simplifications.
3434 if (Instruction::isAssociative(Opcode))
3435 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
3436 return V;
3437
3438 // If the operation is with the result of a select instruction check whether
3439 // operating on either branch of the select always yields the same value.
3440 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3441 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
3442 return V;
3443
3444 // If the operation is with the result of a phi instruction, check whether
3445 // operating on all incoming values of the phi always yields the same value.
3446 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3447 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
3448 return V;
3449
3450 return nullptr;
3451 }
3452 }
3453
SimplifyBinOp(unsigned Opcode,Value * LHS,Value * RHS,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3454 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
3455 const DataLayout *DL, const TargetLibraryInfo *TLI,
3456 const DominatorTree *DT, AssumptionCache *AC,
3457 const Instruction *CxtI) {
3458 return ::SimplifyBinOp(Opcode, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
3459 RecursionLimit);
3460 }
3461
3462 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
3463 /// fold the result.
SimplifyCmpInst(unsigned Predicate,Value * LHS,Value * RHS,const Query & Q,unsigned MaxRecurse)3464 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3465 const Query &Q, unsigned MaxRecurse) {
3466 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
3467 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
3468 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
3469 }
3470
SimplifyCmpInst(unsigned Predicate,Value * LHS,Value * RHS,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3471 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3472 const DataLayout *DL, const TargetLibraryInfo *TLI,
3473 const DominatorTree *DT, AssumptionCache *AC,
3474 const Instruction *CxtI) {
3475 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
3476 RecursionLimit);
3477 }
3478
IsIdempotent(Intrinsic::ID ID)3479 static bool IsIdempotent(Intrinsic::ID ID) {
3480 switch (ID) {
3481 default: return false;
3482
3483 // Unary idempotent: f(f(x)) = f(x)
3484 case Intrinsic::fabs:
3485 case Intrinsic::floor:
3486 case Intrinsic::ceil:
3487 case Intrinsic::trunc:
3488 case Intrinsic::rint:
3489 case Intrinsic::nearbyint:
3490 case Intrinsic::round:
3491 return true;
3492 }
3493 }
3494
3495 template <typename IterTy>
SimplifyIntrinsic(Intrinsic::ID IID,IterTy ArgBegin,IterTy ArgEnd,const Query & Q,unsigned MaxRecurse)3496 static Value *SimplifyIntrinsic(Intrinsic::ID IID, IterTy ArgBegin, IterTy ArgEnd,
3497 const Query &Q, unsigned MaxRecurse) {
3498 // Perform idempotent optimizations
3499 if (!IsIdempotent(IID))
3500 return nullptr;
3501
3502 // Unary Ops
3503 if (std::distance(ArgBegin, ArgEnd) == 1)
3504 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin))
3505 if (II->getIntrinsicID() == IID)
3506 return II;
3507
3508 return nullptr;
3509 }
3510
3511 template <typename IterTy>
SimplifyCall(Value * V,IterTy ArgBegin,IterTy ArgEnd,const Query & Q,unsigned MaxRecurse)3512 static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd,
3513 const Query &Q, unsigned MaxRecurse) {
3514 Type *Ty = V->getType();
3515 if (PointerType *PTy = dyn_cast<PointerType>(Ty))
3516 Ty = PTy->getElementType();
3517 FunctionType *FTy = cast<FunctionType>(Ty);
3518
3519 // call undef -> undef
3520 if (isa<UndefValue>(V))
3521 return UndefValue::get(FTy->getReturnType());
3522
3523 Function *F = dyn_cast<Function>(V);
3524 if (!F)
3525 return nullptr;
3526
3527 if (unsigned IID = F->getIntrinsicID())
3528 if (Value *Ret =
3529 SimplifyIntrinsic((Intrinsic::ID) IID, ArgBegin, ArgEnd, Q, MaxRecurse))
3530 return Ret;
3531
3532 if (!canConstantFoldCallTo(F))
3533 return nullptr;
3534
3535 SmallVector<Constant *, 4> ConstantArgs;
3536 ConstantArgs.reserve(ArgEnd - ArgBegin);
3537 for (IterTy I = ArgBegin, E = ArgEnd; I != E; ++I) {
3538 Constant *C = dyn_cast<Constant>(*I);
3539 if (!C)
3540 return nullptr;
3541 ConstantArgs.push_back(C);
3542 }
3543
3544 return ConstantFoldCall(F, ConstantArgs, Q.TLI);
3545 }
3546
SimplifyCall(Value * V,User::op_iterator ArgBegin,User::op_iterator ArgEnd,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3547 Value *llvm::SimplifyCall(Value *V, User::op_iterator ArgBegin,
3548 User::op_iterator ArgEnd, const DataLayout *DL,
3549 const TargetLibraryInfo *TLI, const DominatorTree *DT,
3550 AssumptionCache *AC, const Instruction *CxtI) {
3551 return ::SimplifyCall(V, ArgBegin, ArgEnd, Query(DL, TLI, DT, AC, CxtI),
3552 RecursionLimit);
3553 }
3554
SimplifyCall(Value * V,ArrayRef<Value * > Args,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,const Instruction * CxtI)3555 Value *llvm::SimplifyCall(Value *V, ArrayRef<Value *> Args,
3556 const DataLayout *DL, const TargetLibraryInfo *TLI,
3557 const DominatorTree *DT, AssumptionCache *AC,
3558 const Instruction *CxtI) {
3559 return ::SimplifyCall(V, Args.begin(), Args.end(),
3560 Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
3561 }
3562
3563 /// SimplifyInstruction - See if we can compute a simplified version of this
3564 /// instruction. If not, this returns null.
SimplifyInstruction(Instruction * I,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC)3565 Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *DL,
3566 const TargetLibraryInfo *TLI,
3567 const DominatorTree *DT, AssumptionCache *AC) {
3568 Value *Result;
3569
3570 switch (I->getOpcode()) {
3571 default:
3572 Result = ConstantFoldInstruction(I, DL, TLI);
3573 break;
3574 case Instruction::FAdd:
3575 Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
3576 I->getFastMathFlags(), DL, TLI, DT, AC, I);
3577 break;
3578 case Instruction::Add:
3579 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
3580 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3581 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
3582 TLI, DT, AC, I);
3583 break;
3584 case Instruction::FSub:
3585 Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
3586 I->getFastMathFlags(), DL, TLI, DT, AC, I);
3587 break;
3588 case Instruction::Sub:
3589 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
3590 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3591 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
3592 TLI, DT, AC, I);
3593 break;
3594 case Instruction::FMul:
3595 Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1),
3596 I->getFastMathFlags(), DL, TLI, DT, AC, I);
3597 break;
3598 case Instruction::Mul:
3599 Result =
3600 SimplifyMulInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
3601 break;
3602 case Instruction::SDiv:
3603 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3604 AC, I);
3605 break;
3606 case Instruction::UDiv:
3607 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3608 AC, I);
3609 break;
3610 case Instruction::FDiv:
3611 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3612 AC, I);
3613 break;
3614 case Instruction::SRem:
3615 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3616 AC, I);
3617 break;
3618 case Instruction::URem:
3619 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3620 AC, I);
3621 break;
3622 case Instruction::FRem:
3623 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
3624 AC, I);
3625 break;
3626 case Instruction::Shl:
3627 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
3628 cast<BinaryOperator>(I)->hasNoSignedWrap(),
3629 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
3630 TLI, DT, AC, I);
3631 break;
3632 case Instruction::LShr:
3633 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
3634 cast<BinaryOperator>(I)->isExact(), DL, TLI, DT,
3635 AC, I);
3636 break;
3637 case Instruction::AShr:
3638 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
3639 cast<BinaryOperator>(I)->isExact(), DL, TLI, DT,
3640 AC, I);
3641 break;
3642 case Instruction::And:
3643 Result =
3644 SimplifyAndInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
3645 break;
3646 case Instruction::Or:
3647 Result =
3648 SimplifyOrInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
3649 break;
3650 case Instruction::Xor:
3651 Result =
3652 SimplifyXorInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
3653 break;
3654 case Instruction::ICmp:
3655 Result =
3656 SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), I->getOperand(0),
3657 I->getOperand(1), DL, TLI, DT, AC, I);
3658 break;
3659 case Instruction::FCmp:
3660 Result =
3661 SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0),
3662 I->getOperand(1), DL, TLI, DT, AC, I);
3663 break;
3664 case Instruction::Select:
3665 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
3666 I->getOperand(2), DL, TLI, DT, AC, I);
3667 break;
3668 case Instruction::GetElementPtr: {
3669 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
3670 Result = SimplifyGEPInst(Ops, DL, TLI, DT, AC, I);
3671 break;
3672 }
3673 case Instruction::InsertValue: {
3674 InsertValueInst *IV = cast<InsertValueInst>(I);
3675 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
3676 IV->getInsertedValueOperand(),
3677 IV->getIndices(), DL, TLI, DT, AC, I);
3678 break;
3679 }
3680 case Instruction::PHI:
3681 Result = SimplifyPHINode(cast<PHINode>(I), Query(DL, TLI, DT, AC, I));
3682 break;
3683 case Instruction::Call: {
3684 CallSite CS(cast<CallInst>(I));
3685 Result = SimplifyCall(CS.getCalledValue(), CS.arg_begin(), CS.arg_end(), DL,
3686 TLI, DT, AC, I);
3687 break;
3688 }
3689 case Instruction::Trunc:
3690 Result =
3691 SimplifyTruncInst(I->getOperand(0), I->getType(), DL, TLI, DT, AC, I);
3692 break;
3693 }
3694
3695 /// If called on unreachable code, the above logic may report that the
3696 /// instruction simplified to itself. Make life easier for users by
3697 /// detecting that case here, returning a safe value instead.
3698 return Result == I ? UndefValue::get(I->getType()) : Result;
3699 }
3700
3701 /// \brief Implementation of recursive simplification through an instructions
3702 /// uses.
3703 ///
3704 /// This is the common implementation of the recursive simplification routines.
3705 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
3706 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
3707 /// instructions to process and attempt to simplify it using
3708 /// InstructionSimplify.
3709 ///
3710 /// This routine returns 'true' only when *it* simplifies something. The passed
3711 /// in simplified value does not count toward this.
replaceAndRecursivelySimplifyImpl(Instruction * I,Value * SimpleV,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC)3712 static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
3713 const DataLayout *DL,
3714 const TargetLibraryInfo *TLI,
3715 const DominatorTree *DT,
3716 AssumptionCache *AC) {
3717 bool Simplified = false;
3718 SmallSetVector<Instruction *, 8> Worklist;
3719
3720 // If we have an explicit value to collapse to, do that round of the
3721 // simplification loop by hand initially.
3722 if (SimpleV) {
3723 for (User *U : I->users())
3724 if (U != I)
3725 Worklist.insert(cast<Instruction>(U));
3726
3727 // Replace the instruction with its simplified value.
3728 I->replaceAllUsesWith(SimpleV);
3729
3730 // Gracefully handle edge cases where the instruction is not wired into any
3731 // parent block.
3732 if (I->getParent())
3733 I->eraseFromParent();
3734 } else {
3735 Worklist.insert(I);
3736 }
3737
3738 // Note that we must test the size on each iteration, the worklist can grow.
3739 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
3740 I = Worklist[Idx];
3741
3742 // See if this instruction simplifies.
3743 SimpleV = SimplifyInstruction(I, DL, TLI, DT, AC);
3744 if (!SimpleV)
3745 continue;
3746
3747 Simplified = true;
3748
3749 // Stash away all the uses of the old instruction so we can check them for
3750 // recursive simplifications after a RAUW. This is cheaper than checking all
3751 // uses of To on the recursive step in most cases.
3752 for (User *U : I->users())
3753 Worklist.insert(cast<Instruction>(U));
3754
3755 // Replace the instruction with its simplified value.
3756 I->replaceAllUsesWith(SimpleV);
3757
3758 // Gracefully handle edge cases where the instruction is not wired into any
3759 // parent block.
3760 if (I->getParent())
3761 I->eraseFromParent();
3762 }
3763 return Simplified;
3764 }
3765
recursivelySimplifyInstruction(Instruction * I,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC)3766 bool llvm::recursivelySimplifyInstruction(Instruction *I, const DataLayout *DL,
3767 const TargetLibraryInfo *TLI,
3768 const DominatorTree *DT,
3769 AssumptionCache *AC) {
3770 return replaceAndRecursivelySimplifyImpl(I, nullptr, DL, TLI, DT, AC);
3771 }
3772
replaceAndRecursivelySimplify(Instruction * I,Value * SimpleV,const DataLayout * DL,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC)3773 bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
3774 const DataLayout *DL,
3775 const TargetLibraryInfo *TLI,
3776 const DominatorTree *DT,
3777 AssumptionCache *AC) {
3778 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
3779 assert(SimpleV && "Must provide a simplified value.");
3780 return replaceAndRecursivelySimplifyImpl(I, SimpleV, DL, TLI, DT, AC);
3781 }
3782