LLVM  10.0.0svn
InstructionSimplify.cpp
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1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements routines for folding instructions into simpler forms
10 // that do not require creating new instructions. This does constant folding
11 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
12 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
13 // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
14 // simplified: This is usually true and assuming it simplifies the logic (if
15 // they have not been simplified then results are correct but maybe suboptimal).
16 //
17 //===----------------------------------------------------------------------===//
18 
20 #include "llvm/ADT/SetVector.h"
21 #include "llvm/ADT/Statistic.h"
31 #include "llvm/IR/ConstantRange.h"
32 #include "llvm/IR/DataLayout.h"
33 #include "llvm/IR/Dominators.h"
35 #include "llvm/IR/GlobalAlias.h"
36 #include "llvm/IR/InstrTypes.h"
37 #include "llvm/IR/Instructions.h"
38 #include "llvm/IR/Operator.h"
39 #include "llvm/IR/PatternMatch.h"
40 #include "llvm/IR/ValueHandle.h"
41 #include "llvm/Support/KnownBits.h"
42 #include <algorithm>
43 using namespace llvm;
44 using namespace llvm::PatternMatch;
45 
46 #define DEBUG_TYPE "instsimplify"
47 
48 enum { RecursionLimit = 3 };
49 
50 STATISTIC(NumExpand, "Number of expansions");
51 STATISTIC(NumReassoc, "Number of reassociations");
52 
53 static Value *SimplifyAndInst(Value *, Value *, const SimplifyQuery &, unsigned);
54 static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned);
55 static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &,
56  const SimplifyQuery &, unsigned);
57 static Value *SimplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &,
58  unsigned);
59 static Value *SimplifyFPBinOp(unsigned, Value *, Value *, const FastMathFlags &,
60  const SimplifyQuery &, unsigned);
61 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &,
62  unsigned);
63 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
64  const SimplifyQuery &Q, unsigned MaxRecurse);
65 static Value *SimplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned);
66 static Value *SimplifyXorInst(Value *, Value *, const SimplifyQuery &, unsigned);
67 static Value *SimplifyCastInst(unsigned, Value *, Type *,
68  const SimplifyQuery &, unsigned);
70  unsigned);
71 
72 static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal,
73  Value *FalseVal) {
74  BinaryOperator::BinaryOps BinOpCode;
75  if (auto *BO = dyn_cast<BinaryOperator>(Cond))
76  BinOpCode = BO->getOpcode();
77  else
78  return nullptr;
79 
80  CmpInst::Predicate ExpectedPred, Pred1, Pred2;
81  if (BinOpCode == BinaryOperator::Or) {
82  ExpectedPred = ICmpInst::ICMP_NE;
83  } else if (BinOpCode == BinaryOperator::And) {
84  ExpectedPred = ICmpInst::ICMP_EQ;
85  } else
86  return nullptr;
87 
88  // %A = icmp eq %TV, %FV
89  // %B = icmp eq %X, %Y (and one of these is a select operand)
90  // %C = and %A, %B
91  // %D = select %C, %TV, %FV
92  // -->
93  // %FV
94 
95  // %A = icmp ne %TV, %FV
96  // %B = icmp ne %X, %Y (and one of these is a select operand)
97  // %C = or %A, %B
98  // %D = select %C, %TV, %FV
99  // -->
100  // %TV
101  Value *X, *Y;
102  if (!match(Cond, m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal),
103  m_Specific(FalseVal)),
104  m_ICmp(Pred2, m_Value(X), m_Value(Y)))) ||
105  Pred1 != Pred2 || Pred1 != ExpectedPred)
106  return nullptr;
107 
108  if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal)
109  return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal;
110 
111  return nullptr;
112 }
113 
114 /// For a boolean type or a vector of boolean type, return false or a vector
115 /// with every element false.
116 static Constant *getFalse(Type *Ty) {
117  return ConstantInt::getFalse(Ty);
118 }
119 
120 /// For a boolean type or a vector of boolean type, return true or a vector
121 /// with every element true.
122 static Constant *getTrue(Type *Ty) {
123  return ConstantInt::getTrue(Ty);
124 }
125 
126 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
127 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
128  Value *RHS) {
129  CmpInst *Cmp = dyn_cast<CmpInst>(V);
130  if (!Cmp)
131  return false;
132  CmpInst::Predicate CPred = Cmp->getPredicate();
133  Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
134  if (CPred == Pred && CLHS == LHS && CRHS == RHS)
135  return true;
136  return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
137  CRHS == LHS;
138 }
139 
140 /// Does the given value dominate the specified phi node?
141 static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
143  if (!I)
144  // Arguments and constants dominate all instructions.
145  return true;
146 
147  // If we are processing instructions (and/or basic blocks) that have not been
148  // fully added to a function, the parent nodes may still be null. Simply
149  // return the conservative answer in these cases.
150  if (!I->getParent() || !P->getParent() || !I->getFunction())
151  return false;
152 
153  // If we have a DominatorTree then do a precise test.
154  if (DT)
155  return DT->dominates(I, P);
156 
157  // Otherwise, if the instruction is in the entry block and is not an invoke,
158  // then it obviously dominates all phi nodes.
159  if (I->getParent() == &I->getFunction()->getEntryBlock() &&
160  !isa<InvokeInst>(I))
161  return true;
162 
163  return false;
164 }
165 
166 /// Simplify "A op (B op' C)" by distributing op over op', turning it into
167 /// "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
168 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
169 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
170 /// Returns the simplified value, or null if no simplification was performed.
172  Instruction::BinaryOps OpcodeToExpand,
173  const SimplifyQuery &Q, unsigned MaxRecurse) {
174  // Recursion is always used, so bail out at once if we already hit the limit.
175  if (!MaxRecurse--)
176  return nullptr;
177 
178  // Check whether the expression has the form "(A op' B) op C".
179  if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
180  if (Op0->getOpcode() == OpcodeToExpand) {
181  // It does! Try turning it into "(A op C) op' (B op C)".
182  Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
183  // Do "A op C" and "B op C" both simplify?
184  if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
185  if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
186  // They do! Return "L op' R" if it simplifies or is already available.
187  // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
188  if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
189  && L == B && R == A)) {
190  ++NumExpand;
191  return LHS;
192  }
193  // Otherwise return "L op' R" if it simplifies.
194  if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
195  ++NumExpand;
196  return V;
197  }
198  }
199  }
200 
201  // Check whether the expression has the form "A op (B op' C)".
202  if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
203  if (Op1->getOpcode() == OpcodeToExpand) {
204  // It does! Try turning it into "(A op B) op' (A op C)".
205  Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
206  // Do "A op B" and "A op C" both simplify?
207  if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
208  if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
209  // They do! Return "L op' R" if it simplifies or is already available.
210  // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
211  if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
212  && L == C && R == B)) {
213  ++NumExpand;
214  return RHS;
215  }
216  // Otherwise return "L op' R" if it simplifies.
217  if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
218  ++NumExpand;
219  return V;
220  }
221  }
222  }
223 
224  return nullptr;
225 }
226 
227 /// Generic simplifications for associative binary operations.
228 /// Returns the simpler value, or null if none was found.
230  Value *LHS, Value *RHS,
231  const SimplifyQuery &Q,
232  unsigned MaxRecurse) {
233  assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
234 
235  // Recursion is always used, so bail out at once if we already hit the limit.
236  if (!MaxRecurse--)
237  return nullptr;
238 
241 
242  // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
243  if (Op0 && Op0->getOpcode() == Opcode) {
244  Value *A = Op0->getOperand(0);
245  Value *B = Op0->getOperand(1);
246  Value *C = RHS;
247 
248  // Does "B op C" simplify?
249  if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
250  // It does! Return "A op V" if it simplifies or is already available.
251  // If V equals B then "A op V" is just the LHS.
252  if (V == B) return LHS;
253  // Otherwise return "A op V" if it simplifies.
254  if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
255  ++NumReassoc;
256  return W;
257  }
258  }
259  }
260 
261  // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
262  if (Op1 && Op1->getOpcode() == Opcode) {
263  Value *A = LHS;
264  Value *B = Op1->getOperand(0);
265  Value *C = Op1->getOperand(1);
266 
267  // Does "A op B" simplify?
268  if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
269  // It does! Return "V op C" if it simplifies or is already available.
270  // If V equals B then "V op C" is just the RHS.
271  if (V == B) return RHS;
272  // Otherwise return "V op C" if it simplifies.
273  if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
274  ++NumReassoc;
275  return W;
276  }
277  }
278  }
279 
280  // The remaining transforms require commutativity as well as associativity.
281  if (!Instruction::isCommutative(Opcode))
282  return nullptr;
283 
284  // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
285  if (Op0 && Op0->getOpcode() == Opcode) {
286  Value *A = Op0->getOperand(0);
287  Value *B = Op0->getOperand(1);
288  Value *C = RHS;
289 
290  // Does "C op A" simplify?
291  if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
292  // It does! Return "V op B" if it simplifies or is already available.
293  // If V equals A then "V op B" is just the LHS.
294  if (V == A) return LHS;
295  // Otherwise return "V op B" if it simplifies.
296  if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
297  ++NumReassoc;
298  return W;
299  }
300  }
301  }
302 
303  // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
304  if (Op1 && Op1->getOpcode() == Opcode) {
305  Value *A = LHS;
306  Value *B = Op1->getOperand(0);
307  Value *C = Op1->getOperand(1);
308 
309  // Does "C op A" simplify?
310  if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
311  // It does! Return "B op V" if it simplifies or is already available.
312  // If V equals C then "B op V" is just the RHS.
313  if (V == C) return RHS;
314  // Otherwise return "B op V" if it simplifies.
315  if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
316  ++NumReassoc;
317  return W;
318  }
319  }
320  }
321 
322  return nullptr;
323 }
324 
325 /// In the case of a binary operation with a select instruction as an operand,
326 /// try to simplify the binop by seeing whether evaluating it on both branches
327 /// of the select results in the same value. Returns the common value if so,
328 /// otherwise returns null.
330  Value *RHS, const SimplifyQuery &Q,
331  unsigned MaxRecurse) {
332  // Recursion is always used, so bail out at once if we already hit the limit.
333  if (!MaxRecurse--)
334  return nullptr;
335 
336  SelectInst *SI;
337  if (isa<SelectInst>(LHS)) {
338  SI = cast<SelectInst>(LHS);
339  } else {
340  assert(isa<SelectInst>(RHS) && "No select instruction operand!");
341  SI = cast<SelectInst>(RHS);
342  }
343 
344  // Evaluate the BinOp on the true and false branches of the select.
345  Value *TV;
346  Value *FV;
347  if (SI == LHS) {
348  TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
349  FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
350  } else {
351  TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
352  FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
353  }
354 
355  // If they simplified to the same value, then return the common value.
356  // If they both failed to simplify then return null.
357  if (TV == FV)
358  return TV;
359 
360  // If one branch simplified to undef, return the other one.
361  if (TV && isa<UndefValue>(TV))
362  return FV;
363  if (FV && isa<UndefValue>(FV))
364  return TV;
365 
366  // If applying the operation did not change the true and false select values,
367  // then the result of the binop is the select itself.
368  if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
369  return SI;
370 
371  // If one branch simplified and the other did not, and the simplified
372  // value is equal to the unsimplified one, return the simplified value.
373  // For example, select (cond, X, X & Z) & Z -> X & Z.
374  if ((FV && !TV) || (TV && !FV)) {
375  // Check that the simplified value has the form "X op Y" where "op" is the
376  // same as the original operation.
377  Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
378  if (Simplified && Simplified->getOpcode() == unsigned(Opcode)) {
379  // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
380  // We already know that "op" is the same as for the simplified value. See
381  // if the operands match too. If so, return the simplified value.
382  Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
383  Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
384  Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
385  if (Simplified->getOperand(0) == UnsimplifiedLHS &&
386  Simplified->getOperand(1) == UnsimplifiedRHS)
387  return Simplified;
388  if (Simplified->isCommutative() &&
389  Simplified->getOperand(1) == UnsimplifiedLHS &&
390  Simplified->getOperand(0) == UnsimplifiedRHS)
391  return Simplified;
392  }
393  }
394 
395  return nullptr;
396 }
397 
398 /// In the case of a comparison with a select instruction, try to simplify the
399 /// comparison by seeing whether both branches of the select result in the same
400 /// value. Returns the common value if so, otherwise returns null.
402  Value *RHS, const SimplifyQuery &Q,
403  unsigned MaxRecurse) {
404  // Recursion is always used, so bail out at once if we already hit the limit.
405  if (!MaxRecurse--)
406  return nullptr;
407 
408  // Make sure the select is on the LHS.
409  if (!isa<SelectInst>(LHS)) {
410  std::swap(LHS, RHS);
411  Pred = CmpInst::getSwappedPredicate(Pred);
412  }
413  assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
414  SelectInst *SI = cast<SelectInst>(LHS);
415  Value *Cond = SI->getCondition();
416  Value *TV = SI->getTrueValue();
417  Value *FV = SI->getFalseValue();
418 
419  // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
420  // Does "cmp TV, RHS" simplify?
421  Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
422  if (TCmp == Cond) {
423  // It not only simplified, it simplified to the select condition. Replace
424  // it with 'true'.
425  TCmp = getTrue(Cond->getType());
426  } else if (!TCmp) {
427  // It didn't simplify. However if "cmp TV, RHS" is equal to the select
428  // condition then we can replace it with 'true'. Otherwise give up.
429  if (!isSameCompare(Cond, Pred, TV, RHS))
430  return nullptr;
431  TCmp = getTrue(Cond->getType());
432  }
433 
434  // Does "cmp FV, RHS" simplify?
435  Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
436  if (FCmp == Cond) {
437  // It not only simplified, it simplified to the select condition. Replace
438  // it with 'false'.
439  FCmp = getFalse(Cond->getType());
440  } else if (!FCmp) {
441  // It didn't simplify. However if "cmp FV, RHS" is equal to the select
442  // condition then we can replace it with 'false'. Otherwise give up.
443  if (!isSameCompare(Cond, Pred, FV, RHS))
444  return nullptr;
445  FCmp = getFalse(Cond->getType());
446  }
447 
448  // If both sides simplified to the same value, then use it as the result of
449  // the original comparison.
450  if (TCmp == FCmp)
451  return TCmp;
452 
453  // The remaining cases only make sense if the select condition has the same
454  // type as the result of the comparison, so bail out if this is not so.
455  if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
456  return nullptr;
457  // If the false value simplified to false, then the result of the compare
458  // is equal to "Cond && TCmp". This also catches the case when the false
459  // value simplified to false and the true value to true, returning "Cond".
460  if (match(FCmp, m_Zero()))
461  if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
462  return V;
463  // If the true value simplified to true, then the result of the compare
464  // is equal to "Cond || FCmp".
465  if (match(TCmp, m_One()))
466  if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
467  return V;
468  // Finally, if the false value simplified to true and the true value to
469  // false, then the result of the compare is equal to "!Cond".
470  if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
471  if (Value *V =
472  SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
473  Q, MaxRecurse))
474  return V;
475 
476  return nullptr;
477 }
478 
479 /// In the case of a binary operation with an operand that is a PHI instruction,
480 /// try to simplify the binop by seeing whether evaluating it on the incoming
481 /// phi values yields the same result for every value. If so returns the common
482 /// value, otherwise returns null.
484  Value *RHS, const SimplifyQuery &Q,
485  unsigned MaxRecurse) {
486  // Recursion is always used, so bail out at once if we already hit the limit.
487  if (!MaxRecurse--)
488  return nullptr;
489 
490  PHINode *PI;
491  if (isa<PHINode>(LHS)) {
492  PI = cast<PHINode>(LHS);
493  // Bail out if RHS and the phi may be mutually interdependent due to a loop.
494  if (!valueDominatesPHI(RHS, PI, Q.DT))
495  return nullptr;
496  } else {
497  assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
498  PI = cast<PHINode>(RHS);
499  // Bail out if LHS and the phi may be mutually interdependent due to a loop.
500  if (!valueDominatesPHI(LHS, PI, Q.DT))
501  return nullptr;
502  }
503 
504  // Evaluate the BinOp on the incoming phi values.
505  Value *CommonValue = nullptr;
506  for (Value *Incoming : PI->incoming_values()) {
507  // If the incoming value is the phi node itself, it can safely be skipped.
508  if (Incoming == PI) continue;
509  Value *V = PI == LHS ?
510  SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
511  SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
512  // If the operation failed to simplify, or simplified to a different value
513  // to previously, then give up.
514  if (!V || (CommonValue && V != CommonValue))
515  return nullptr;
516  CommonValue = V;
517  }
518 
519  return CommonValue;
520 }
521 
522 /// In the case of a comparison with a PHI instruction, try to simplify the
523 /// comparison by seeing whether comparing with all of the incoming phi values
524 /// yields the same result every time. If so returns the common result,
525 /// otherwise returns null.
527  const SimplifyQuery &Q, unsigned MaxRecurse) {
528  // Recursion is always used, so bail out at once if we already hit the limit.
529  if (!MaxRecurse--)
530  return nullptr;
531 
532  // Make sure the phi is on the LHS.
533  if (!isa<PHINode>(LHS)) {
534  std::swap(LHS, RHS);
535  Pred = CmpInst::getSwappedPredicate(Pred);
536  }
537  assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
538  PHINode *PI = cast<PHINode>(LHS);
539 
540  // Bail out if RHS and the phi may be mutually interdependent due to a loop.
541  if (!valueDominatesPHI(RHS, PI, Q.DT))
542  return nullptr;
543 
544  // Evaluate the BinOp on the incoming phi values.
545  Value *CommonValue = nullptr;
546  for (Value *Incoming : PI->incoming_values()) {
547  // If the incoming value is the phi node itself, it can safely be skipped.
548  if (Incoming == PI) continue;
549  Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
550  // If the operation failed to simplify, or simplified to a different value
551  // to previously, then give up.
552  if (!V || (CommonValue && V != CommonValue))
553  return nullptr;
554  CommonValue = V;
555  }
556 
557  return CommonValue;
558 }
559 
561  Value *&Op0, Value *&Op1,
562  const SimplifyQuery &Q) {
563  if (auto *CLHS = dyn_cast<Constant>(Op0)) {
564  if (auto *CRHS = dyn_cast<Constant>(Op1))
565  return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL);
566 
567  // Canonicalize the constant to the RHS if this is a commutative operation.
568  if (Instruction::isCommutative(Opcode))
569  std::swap(Op0, Op1);
570  }
571  return nullptr;
572 }
573 
574 /// Given operands for an Add, see if we can fold the result.
575 /// If not, this returns null.
576 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
577  const SimplifyQuery &Q, unsigned MaxRecurse) {
578  if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q))
579  return C;
580 
581  // X + undef -> undef
582  if (match(Op1, m_Undef()))
583  return Op1;
584 
585  // X + 0 -> X
586  if (match(Op1, m_Zero()))
587  return Op0;
588 
589  // If two operands are negative, return 0.
590  if (isKnownNegation(Op0, Op1))
591  return Constant::getNullValue(Op0->getType());
592 
593  // X + (Y - X) -> Y
594  // (Y - X) + X -> Y
595  // Eg: X + -X -> 0
596  Value *Y = nullptr;
597  if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
598  match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
599  return Y;
600 
601  // X + ~X -> -1 since ~X = -X-1
602  Type *Ty = Op0->getType();
603  if (match(Op0, m_Not(m_Specific(Op1))) ||
604  match(Op1, m_Not(m_Specific(Op0))))
605  return Constant::getAllOnesValue(Ty);
606 
607  // add nsw/nuw (xor Y, signmask), signmask --> Y
608  // The no-wrapping add guarantees that the top bit will be set by the add.
609  // Therefore, the xor must be clearing the already set sign bit of Y.
610  if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) &&
611  match(Op0, m_Xor(m_Value(Y), m_SignMask())))
612  return Y;
613 
614  // add nuw %x, -1 -> -1, because %x can only be 0.
615  if (IsNUW && match(Op1, m_AllOnes()))
616  return Op1; // Which is -1.
617 
618  /// i1 add -> xor.
619  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
620  if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
621  return V;
622 
623  // Try some generic simplifications for associative operations.
624  if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
625  MaxRecurse))
626  return V;
627 
628  // Threading Add over selects and phi nodes is pointless, so don't bother.
629  // Threading over the select in "A + select(cond, B, C)" means evaluating
630  // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
631  // only if B and C are equal. If B and C are equal then (since we assume
632  // that operands have already been simplified) "select(cond, B, C)" should
633  // have been simplified to the common value of B and C already. Analysing
634  // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
635  // for threading over phi nodes.
636 
637  return nullptr;
638 }
639 
640 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
641  const SimplifyQuery &Query) {
642  return ::SimplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit);
643 }
644 
645 /// Compute the base pointer and cumulative constant offsets for V.
646 ///
647 /// This strips all constant offsets off of V, leaving it the base pointer, and
648 /// accumulates the total constant offset applied in the returned constant. It
649 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
650 /// no constant offsets applied.
651 ///
652 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
653 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
654 /// folding.
656  bool AllowNonInbounds = false) {
658 
659  Type *IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType();
660  APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
661 
662  V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds);
663  // As that strip may trace through `addrspacecast`, need to sext or trunc
664  // the offset calculated.
665  IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType();
666  Offset = Offset.sextOrTrunc(IntPtrTy->getIntegerBitWidth());
667 
668  Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
669  if (V->getType()->isVectorTy())
670  return ConstantVector::getSplat(V->getType()->getVectorNumElements(),
671  OffsetIntPtr);
672  return OffsetIntPtr;
673 }
674 
675 /// Compute the constant difference between two pointer values.
676 /// If the difference is not a constant, returns zero.
678  Value *RHS) {
679  Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
680  Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
681 
682  // If LHS and RHS are not related via constant offsets to the same base
683  // value, there is nothing we can do here.
684  if (LHS != RHS)
685  return nullptr;
686 
687  // Otherwise, the difference of LHS - RHS can be computed as:
688  // LHS - RHS
689  // = (LHSOffset + Base) - (RHSOffset + Base)
690  // = LHSOffset - RHSOffset
691  return ConstantExpr::getSub(LHSOffset, RHSOffset);
692 }
693 
694 /// Given operands for a Sub, see if we can fold the result.
695 /// If not, this returns null.
696 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
697  const SimplifyQuery &Q, unsigned MaxRecurse) {
698  if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q))
699  return C;
700 
701  // X - undef -> undef
702  // undef - X -> undef
703  if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
704  return UndefValue::get(Op0->getType());
705 
706  // X - 0 -> X
707  if (match(Op1, m_Zero()))
708  return Op0;
709 
710  // X - X -> 0
711  if (Op0 == Op1)
712  return Constant::getNullValue(Op0->getType());
713 
714  // Is this a negation?
715  if (match(Op0, m_Zero())) {
716  // 0 - X -> 0 if the sub is NUW.
717  if (isNUW)
718  return Constant::getNullValue(Op0->getType());
719 
720  KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
721  if (Known.Zero.isMaxSignedValue()) {
722  // Op1 is either 0 or the minimum signed value. If the sub is NSW, then
723  // Op1 must be 0 because negating the minimum signed value is undefined.
724  if (isNSW)
725  return Constant::getNullValue(Op0->getType());
726 
727  // 0 - X -> X if X is 0 or the minimum signed value.
728  return Op1;
729  }
730  }
731 
732  // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
733  // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
734  Value *X = nullptr, *Y = nullptr, *Z = Op1;
735  if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
736  // See if "V === Y - Z" simplifies.
737  if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
738  // It does! Now see if "X + V" simplifies.
739  if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
740  // It does, we successfully reassociated!
741  ++NumReassoc;
742  return W;
743  }
744  // See if "V === X - Z" simplifies.
745  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
746  // It does! Now see if "Y + V" simplifies.
747  if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
748  // It does, we successfully reassociated!
749  ++NumReassoc;
750  return W;
751  }
752  }
753 
754  // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
755  // For example, X - (X + 1) -> -1
756  X = Op0;
757  if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
758  // See if "V === X - Y" simplifies.
759  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
760  // It does! Now see if "V - Z" simplifies.
761  if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
762  // It does, we successfully reassociated!
763  ++NumReassoc;
764  return W;
765  }
766  // See if "V === X - Z" simplifies.
767  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
768  // It does! Now see if "V - Y" simplifies.
769  if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
770  // It does, we successfully reassociated!
771  ++NumReassoc;
772  return W;
773  }
774  }
775 
776  // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
777  // For example, X - (X - Y) -> Y.
778  Z = Op0;
779  if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
780  // See if "V === Z - X" simplifies.
781  if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
782  // It does! Now see if "V + Y" simplifies.
783  if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
784  // It does, we successfully reassociated!
785  ++NumReassoc;
786  return W;
787  }
788 
789  // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
790  if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
791  match(Op1, m_Trunc(m_Value(Y))))
792  if (X->getType() == Y->getType())
793  // See if "V === X - Y" simplifies.
794  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
795  // It does! Now see if "trunc V" simplifies.
796  if (Value *W = SimplifyCastInst(Instruction::Trunc, V, Op0->getType(),
797  Q, MaxRecurse - 1))
798  // It does, return the simplified "trunc V".
799  return W;
800 
801  // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
802  if (match(Op0, m_PtrToInt(m_Value(X))) &&
803  match(Op1, m_PtrToInt(m_Value(Y))))
804  if (Constant *Result = computePointerDifference(Q.DL, X, Y))
805  return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
806 
807  // i1 sub -> xor.
808  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
809  if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
810  return V;
811 
812  // Threading Sub over selects and phi nodes is pointless, so don't bother.
813  // Threading over the select in "A - select(cond, B, C)" means evaluating
814  // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
815  // only if B and C are equal. If B and C are equal then (since we assume
816  // that operands have already been simplified) "select(cond, B, C)" should
817  // have been simplified to the common value of B and C already. Analysing
818  // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
819  // for threading over phi nodes.
820 
821  return nullptr;
822 }
823 
824 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
825  const SimplifyQuery &Q) {
826  return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
827 }
828 
829 /// Given operands for a Mul, see if we can fold the result.
830 /// If not, this returns null.
831 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
832  unsigned MaxRecurse) {
833  if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q))
834  return C;
835 
836  // X * undef -> 0
837  // X * 0 -> 0
838  if (match(Op1, m_CombineOr(m_Undef(), m_Zero())))
839  return Constant::getNullValue(Op0->getType());
840 
841  // X * 1 -> X
842  if (match(Op1, m_One()))
843  return Op0;
844 
845  // (X / Y) * Y -> X if the division is exact.
846  Value *X = nullptr;
847  if (Q.IIQ.UseInstrInfo &&
848  (match(Op0,
849  m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
850  match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))) // Y * (X / Y)
851  return X;
852 
853  // i1 mul -> and.
854  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
855  if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
856  return V;
857 
858  // Try some generic simplifications for associative operations.
859  if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
860  MaxRecurse))
861  return V;
862 
863  // Mul distributes over Add. Try some generic simplifications based on this.
864  if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
865  Q, MaxRecurse))
866  return V;
867 
868  // If the operation is with the result of a select instruction, check whether
869  // operating on either branch of the select always yields the same value.
870  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
871  if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
872  MaxRecurse))
873  return V;
874 
875  // If the operation is with the result of a phi instruction, check whether
876  // operating on all incoming values of the phi always yields the same value.
877  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
878  if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
879  MaxRecurse))
880  return V;
881 
882  return nullptr;
883 }
884 
887 }
888 
889 /// Check for common or similar folds of integer division or integer remainder.
890 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem).
891 static Value *simplifyDivRem(Value *Op0, Value *Op1, bool IsDiv) {
892  Type *Ty = Op0->getType();
893 
894  // X / undef -> undef
895  // X % undef -> undef
896  if (match(Op1, m_Undef()))
897  return Op1;
898 
899  // X / 0 -> undef
900  // X % 0 -> undef
901  // We don't need to preserve faults!
902  if (match(Op1, m_Zero()))
903  return UndefValue::get(Ty);
904 
905  // If any element of a constant divisor vector is zero or undef, the whole op
906  // is undef.
907  auto *Op1C = dyn_cast<Constant>(Op1);
908  if (Op1C && Ty->isVectorTy()) {
909  unsigned NumElts = Ty->getVectorNumElements();
910  for (unsigned i = 0; i != NumElts; ++i) {
911  Constant *Elt = Op1C->getAggregateElement(i);
912  if (Elt && (Elt->isNullValue() || isa<UndefValue>(Elt)))
913  return UndefValue::get(Ty);
914  }
915  }
916 
917  // undef / X -> 0
918  // undef % X -> 0
919  if (match(Op0, m_Undef()))
920  return Constant::getNullValue(Ty);
921 
922  // 0 / X -> 0
923  // 0 % X -> 0
924  if (match(Op0, m_Zero()))
925  return Constant::getNullValue(Op0->getType());
926 
927  // X / X -> 1
928  // X % X -> 0
929  if (Op0 == Op1)
930  return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty);
931 
932  // X / 1 -> X
933  // X % 1 -> 0
934  // If this is a boolean op (single-bit element type), we can't have
935  // division-by-zero or remainder-by-zero, so assume the divisor is 1.
936  // Similarly, if we're zero-extending a boolean divisor, then assume it's a 1.
937  Value *X;
938  if (match(Op1, m_One()) || Ty->isIntOrIntVectorTy(1) ||
939  (match(Op1, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)))
940  return IsDiv ? Op0 : Constant::getNullValue(Ty);
941 
942  return nullptr;
943 }
944 
945 /// Given a predicate and two operands, return true if the comparison is true.
946 /// This is a helper for div/rem simplification where we return some other value
947 /// when we can prove a relationship between the operands.
948 static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS,
949  const SimplifyQuery &Q, unsigned MaxRecurse) {
950  Value *V = SimplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse);
951  Constant *C = dyn_cast_or_null<Constant>(V);
952  return (C && C->isAllOnesValue());
953 }
954 
955 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer
956 /// to simplify X % Y to X.
957 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q,
958  unsigned MaxRecurse, bool IsSigned) {
959  // Recursion is always used, so bail out at once if we already hit the limit.
960  if (!MaxRecurse--)
961  return false;
962 
963  if (IsSigned) {
964  // |X| / |Y| --> 0
965  //
966  // We require that 1 operand is a simple constant. That could be extended to
967  // 2 variables if we computed the sign bit for each.
968  //
969  // Make sure that a constant is not the minimum signed value because taking
970  // the abs() of that is undefined.
971  Type *Ty = X->getType();
972  const APInt *C;
973  if (match(X, m_APInt(C)) && !C->isMinSignedValue()) {
974  // Is the variable divisor magnitude always greater than the constant
975  // dividend magnitude?
976  // |Y| > |C| --> Y < -abs(C) or Y > abs(C)
977  Constant *PosDividendC = ConstantInt::get(Ty, C->abs());
978  Constant *NegDividendC = ConstantInt::get(Ty, -C->abs());
979  if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) ||
980  isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse))
981  return true;
982  }
983  if (match(Y, m_APInt(C))) {
984  // Special-case: we can't take the abs() of a minimum signed value. If
985  // that's the divisor, then all we have to do is prove that the dividend
986  // is also not the minimum signed value.
987  if (C->isMinSignedValue())
988  return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse);
989 
990  // Is the variable dividend magnitude always less than the constant
991  // divisor magnitude?
992  // |X| < |C| --> X > -abs(C) and X < abs(C)
993  Constant *PosDivisorC = ConstantInt::get(Ty, C->abs());
994  Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs());
995  if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) &&
996  isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse))
997  return true;
998  }
999  return false;
1000  }
1001 
1002  // IsSigned == false.
1003  // Is the dividend unsigned less than the divisor?
1004  return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse);
1005 }
1006 
1007 /// These are simplifications common to SDiv and UDiv.
1009  const SimplifyQuery &Q, unsigned MaxRecurse) {
1010  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1011  return C;
1012 
1013  if (Value *V = simplifyDivRem(Op0, Op1, true))
1014  return V;
1015 
1016  bool IsSigned = Opcode == Instruction::SDiv;
1017 
1018  // (X * Y) / Y -> X if the multiplication does not overflow.
1019  Value *X;
1020  if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) {
1021  auto *Mul = cast<OverflowingBinaryOperator>(Op0);
1022  // If the Mul does not overflow, then we are good to go.
1023  if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) ||
1024  (!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul)))
1025  return X;
1026  // If X has the form X = A / Y, then X * Y cannot overflow.
1027  if ((IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) ||
1028  (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1)))))
1029  return X;
1030  }
1031 
1032  // (X rem Y) / Y -> 0
1033  if ((IsSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1034  (!IsSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1035  return Constant::getNullValue(Op0->getType());
1036 
1037  // (X /u C1) /u C2 -> 0 if C1 * C2 overflow
1038  ConstantInt *C1, *C2;
1039  if (!IsSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
1040  match(Op1, m_ConstantInt(C2))) {
1041  bool Overflow;
1042  (void)C1->getValue().umul_ov(C2->getValue(), Overflow);
1043  if (Overflow)
1044  return Constant::getNullValue(Op0->getType());
1045  }
1046 
1047  // If the operation is with the result of a select instruction, check whether
1048  // operating on either branch of the select always yields the same value.
1049  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1050  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1051  return V;
1052 
1053  // If the operation is with the result of a phi instruction, check whether
1054  // operating on all incoming values of the phi always yields the same value.
1055  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1056  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1057  return V;
1058 
1059  if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned))
1060  return Constant::getNullValue(Op0->getType());
1061 
1062  return nullptr;
1063 }
1064 
1065 /// These are simplifications common to SRem and URem.
1067  const SimplifyQuery &Q, unsigned MaxRecurse) {
1068  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1069  return C;
1070 
1071  if (Value *V = simplifyDivRem(Op0, Op1, false))
1072  return V;
1073 
1074  // (X % Y) % Y -> X % Y
1075  if ((Opcode == Instruction::SRem &&
1076  match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1077  (Opcode == Instruction::URem &&
1078  match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1079  return Op0;
1080 
1081  // (X << Y) % X -> 0
1082  if (Q.IIQ.UseInstrInfo &&
1083  ((Opcode == Instruction::SRem &&
1084  match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) ||
1085  (Opcode == Instruction::URem &&
1086  match(Op0, m_NUWShl(m_Specific(Op1), m_Value())))))
1087  return Constant::getNullValue(Op0->getType());
1088 
1089  // If the operation is with the result of a select instruction, check whether
1090  // operating on either branch of the select always yields the same value.
1091  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1092  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1093  return V;
1094 
1095  // If the operation is with the result of a phi instruction, check whether
1096  // operating on all incoming values of the phi always yields the same value.
1097  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1098  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1099  return V;
1100 
1101  // If X / Y == 0, then X % Y == X.
1102  if (isDivZero(Op0, Op1, Q, MaxRecurse, Opcode == Instruction::SRem))
1103  return Op0;
1104 
1105  return nullptr;
1106 }
1107 
1108 /// Given operands for an SDiv, see if we can fold the result.
1109 /// If not, this returns null.
1110 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1111  unsigned MaxRecurse) {
1112  // If two operands are negated and no signed overflow, return -1.
1113  if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true))
1114  return Constant::getAllOnesValue(Op0->getType());
1115 
1116  return simplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse);
1117 }
1118 
1121 }
1122 
1123 /// Given operands for a UDiv, see if we can fold the result.
1124 /// If not, this returns null.
1125 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1126  unsigned MaxRecurse) {
1127  return simplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse);
1128 }
1129 
1132 }
1133 
1134 /// Given operands for an SRem, see if we can fold the result.
1135 /// If not, this returns null.
1136 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1137  unsigned MaxRecurse) {
1138  // If the divisor is 0, the result is undefined, so assume the divisor is -1.
1139  // srem Op0, (sext i1 X) --> srem Op0, -1 --> 0
1140  Value *X;
1141  if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))
1142  return ConstantInt::getNullValue(Op0->getType());
1143 
1144  // If the two operands are negated, return 0.
1145  if (isKnownNegation(Op0, Op1))
1146  return ConstantInt::getNullValue(Op0->getType());
1147 
1148  return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse);
1149 }
1150 
1153 }
1154 
1155 /// Given operands for a URem, see if we can fold the result.
1156 /// If not, this returns null.
1157 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1158  unsigned MaxRecurse) {
1159  return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse);
1160 }
1161 
1164 }
1165 
1166 /// Returns true if a shift by \c Amount always yields undef.
1167 static bool isUndefShift(Value *Amount) {
1168  Constant *C = dyn_cast<Constant>(Amount);
1169  if (!C)
1170  return false;
1171 
1172  // X shift by undef -> undef because it may shift by the bitwidth.
1173  if (isa<UndefValue>(C))
1174  return true;
1175 
1176  // Shifting by the bitwidth or more is undefined.
1177  if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
1178  if (CI->getValue().getLimitedValue() >=
1179  CI->getType()->getScalarSizeInBits())
1180  return true;
1181 
1182  // If all lanes of a vector shift are undefined the whole shift is.
1183  if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
1184  for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I)
1186  return false;
1187  return true;
1188  }
1189 
1190  return false;
1191 }
1192 
1193 /// Given operands for an Shl, LShr or AShr, see if we can fold the result.
1194 /// If not, this returns null.
1196  Value *Op1, const SimplifyQuery &Q, unsigned MaxRecurse) {
1197  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1198  return C;
1199 
1200  // 0 shift by X -> 0
1201  if (match(Op0, m_Zero()))
1202  return Constant::getNullValue(Op0->getType());
1203 
1204  // X shift by 0 -> X
1205  // Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones
1206  // would be poison.
1207  Value *X;
1208  if (match(Op1, m_Zero()) ||
1209  (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)))
1210  return Op0;
1211 
1212  // Fold undefined shifts.
1213  if (isUndefShift(Op1))
1214  return UndefValue::get(Op0->getType());
1215 
1216  // If the operation is with the result of a select instruction, check whether
1217  // operating on either branch of the select always yields the same value.
1218  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1219  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1220  return V;
1221 
1222  // If the operation is with the result of a phi instruction, check whether
1223  // operating on all incoming values of the phi always yields the same value.
1224  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1225  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1226  return V;
1227 
1228  // If any bits in the shift amount make that value greater than or equal to
1229  // the number of bits in the type, the shift is undefined.
1230  KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1231  if (Known.One.getLimitedValue() >= Known.getBitWidth())
1232  return UndefValue::get(Op0->getType());
1233 
1234  // If all valid bits in the shift amount are known zero, the first operand is
1235  // unchanged.
1236  unsigned NumValidShiftBits = Log2_32_Ceil(Known.getBitWidth());
1237  if (Known.countMinTrailingZeros() >= NumValidShiftBits)
1238  return Op0;
1239 
1240  return nullptr;
1241 }
1242 
1243 /// Given operands for an Shl, LShr or AShr, see if we can
1244 /// fold the result. If not, this returns null.
1246  Value *Op1, bool isExact, const SimplifyQuery &Q,
1247  unsigned MaxRecurse) {
1248  if (Value *V = SimplifyShift(Opcode, Op0, Op1, Q, MaxRecurse))
1249  return V;
1250 
1251  // X >> X -> 0
1252  if (Op0 == Op1)
1253  return Constant::getNullValue(Op0->getType());
1254 
1255  // undef >> X -> 0
1256  // undef >> X -> undef (if it's exact)
1257  if (match(Op0, m_Undef()))
1258  return isExact ? Op0 : Constant::getNullValue(Op0->getType());
1259 
1260  // The low bit cannot be shifted out of an exact shift if it is set.
1261  if (isExact) {
1262  KnownBits Op0Known = computeKnownBits(Op0, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
1263  if (Op0Known.One[0])
1264  return Op0;
1265  }
1266 
1267  return nullptr;
1268 }
1269 
1270 /// Given operands for an Shl, see if we can fold the result.
1271 /// If not, this returns null.
1272 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1273  const SimplifyQuery &Q, unsigned MaxRecurse) {
1274  if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1275  return V;
1276 
1277  // undef << X -> 0
1278  // undef << X -> undef if (if it's NSW/NUW)
1279  if (match(Op0, m_Undef()))
1280  return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType());
1281 
1282  // (X >> A) << A -> X
1283  Value *X;
1284  if (Q.IIQ.UseInstrInfo &&
1285  match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1286  return X;
1287 
1288  // shl nuw i8 C, %x -> C iff C has sign bit set.
1289  if (isNUW && match(Op0, m_Negative()))
1290  return Op0;
1291  // NOTE: could use computeKnownBits() / LazyValueInfo,
1292  // but the cost-benefit analysis suggests it isn't worth it.
1293 
1294  return nullptr;
1295 }
1296 
1297 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1298  const SimplifyQuery &Q) {
1299  return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
1300 }
1301 
1302 /// Given operands for an LShr, see if we can fold the result.
1303 /// If not, this returns null.
1304 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1305  const SimplifyQuery &Q, unsigned MaxRecurse) {
1306  if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q,
1307  MaxRecurse))
1308  return V;
1309 
1310  // (X << A) >> A -> X
1311  Value *X;
1312  if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
1313  return X;
1314 
1315  // ((X << A) | Y) >> A -> X if effective width of Y is not larger than A.
1316  // We can return X as we do in the above case since OR alters no bits in X.
1317  // SimplifyDemandedBits in InstCombine can do more general optimization for
1318  // bit manipulation. This pattern aims to provide opportunities for other
1319  // optimizers by supporting a simple but common case in InstSimplify.
1320  Value *Y;
1321  const APInt *ShRAmt, *ShLAmt;
1322  if (match(Op1, m_APInt(ShRAmt)) &&
1323  match(Op0, m_c_Or(m_NUWShl(m_Value(X), m_APInt(ShLAmt)), m_Value(Y))) &&
1324  *ShRAmt == *ShLAmt) {
1325  const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1326  const unsigned Width = Op0->getType()->getScalarSizeInBits();
1327  const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros();
1328  if (ShRAmt->uge(EffWidthY))
1329  return X;
1330  }
1331 
1332  return nullptr;
1333 }
1334 
1335 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1336  const SimplifyQuery &Q) {
1337  return ::SimplifyLShrInst(Op0, Op1, isExact, Q, RecursionLimit);
1338 }
1339 
1340 /// Given operands for an AShr, see if we can fold the result.
1341 /// If not, this returns null.
1342 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1343  const SimplifyQuery &Q, unsigned MaxRecurse) {
1344  if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
1345  MaxRecurse))
1346  return V;
1347 
1348  // all ones >>a X -> -1
1349  // Do not return Op0 because it may contain undef elements if it's a vector.
1350  if (match(Op0, m_AllOnes()))
1351  return Constant::getAllOnesValue(Op0->getType());
1352 
1353  // (X << A) >> A -> X
1354  Value *X;
1355  if (Q.IIQ.UseInstrInfo && match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
1356  return X;
1357 
1358  // Arithmetic shifting an all-sign-bit value is a no-op.
1359  unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1360  if (NumSignBits == Op0->getType()->getScalarSizeInBits())
1361  return Op0;
1362 
1363  return nullptr;
1364 }
1365 
1366 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1367  const SimplifyQuery &Q) {
1368  return ::SimplifyAShrInst(Op0, Op1, isExact, Q, RecursionLimit);
1369 }
1370 
1371 /// Commuted variants are assumed to be handled by calling this function again
1372 /// with the parameters swapped.
1374  ICmpInst *UnsignedICmp, bool IsAnd) {
1375  Value *X, *Y;
1376 
1377  ICmpInst::Predicate EqPred;
1378  if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) ||
1379  !ICmpInst::isEquality(EqPred))
1380  return nullptr;
1381 
1382  ICmpInst::Predicate UnsignedPred;
1383  if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
1384  ICmpInst::isUnsigned(UnsignedPred))
1385  ;
1386  else if (match(UnsignedICmp,
1387  m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) &&
1388  ICmpInst::isUnsigned(UnsignedPred))
1389  UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
1390  else
1391  return nullptr;
1392 
1393  // X < Y && Y != 0 --> X < Y
1394  // X < Y || Y != 0 --> Y != 0
1395  if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE)
1396  return IsAnd ? UnsignedICmp : ZeroICmp;
1397 
1398  // X >= Y || Y != 0 --> true
1399  // X >= Y || Y == 0 --> X >= Y
1400  if (UnsignedPred == ICmpInst::ICMP_UGE && !IsAnd) {
1401  if (EqPred == ICmpInst::ICMP_NE)
1402  return getTrue(UnsignedICmp->getType());
1403  return UnsignedICmp;
1404  }
1405 
1406  // X < Y && Y == 0 --> false
1407  if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
1408  IsAnd)
1409  return getFalse(UnsignedICmp->getType());
1410 
1411  return nullptr;
1412 }
1413 
1414 /// Commuted variants are assumed to be handled by calling this function again
1415 /// with the parameters swapped.
1417  ICmpInst::Predicate Pred0, Pred1;
1418  Value *A ,*B;
1419  if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
1420  !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
1421  return nullptr;
1422 
1423  // We have (icmp Pred0, A, B) & (icmp Pred1, A, B).
1424  // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
1425  // can eliminate Op1 from this 'and'.
1426  if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
1427  return Op0;
1428 
1429  // Check for any combination of predicates that are guaranteed to be disjoint.
1430  if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
1431  (Pred0 == ICmpInst::ICMP_EQ && ICmpInst::isFalseWhenEqual(Pred1)) ||
1432  (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT) ||
1433  (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT))
1434  return getFalse(Op0->getType());
1435 
1436  return nullptr;
1437 }
1438 
1439 /// Commuted variants are assumed to be handled by calling this function again
1440 /// with the parameters swapped.
1442  ICmpInst::Predicate Pred0, Pred1;
1443  Value *A ,*B;
1444  if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
1445  !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
1446  return nullptr;
1447 
1448  // We have (icmp Pred0, A, B) | (icmp Pred1, A, B).
1449  // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
1450  // can eliminate Op0 from this 'or'.
1451  if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
1452  return Op1;
1453 
1454  // Check for any combination of predicates that cover the entire range of
1455  // possibilities.
1456  if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
1457  (Pred0 == ICmpInst::ICMP_NE && ICmpInst::isTrueWhenEqual(Pred1)) ||
1458  (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGE) ||
1459  (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGE))
1460  return getTrue(Op0->getType());
1461 
1462  return nullptr;
1463 }
1464 
1465 /// Test if a pair of compares with a shared operand and 2 constants has an
1466 /// empty set intersection, full set union, or if one compare is a superset of
1467 /// the other.
1469  bool IsAnd) {
1470  // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)).
1471  if (Cmp0->getOperand(0) != Cmp1->getOperand(0))
1472  return nullptr;
1473 
1474  const APInt *C0, *C1;
1475  if (!match(Cmp0->getOperand(1), m_APInt(C0)) ||
1476  !match(Cmp1->getOperand(1), m_APInt(C1)))
1477  return nullptr;
1478 
1479  auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0);
1480  auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1);
1481 
1482  // For and-of-compares, check if the intersection is empty:
1483  // (icmp X, C0) && (icmp X, C1) --> empty set --> false
1484  if (IsAnd && Range0.intersectWith(Range1).isEmptySet())
1485  return getFalse(Cmp0->getType());
1486 
1487  // For or-of-compares, check if the union is full:
1488  // (icmp X, C0) || (icmp X, C1) --> full set --> true
1489  if (!IsAnd && Range0.unionWith(Range1).isFullSet())
1490  return getTrue(Cmp0->getType());
1491 
1492  // Is one range a superset of the other?
1493  // If this is and-of-compares, take the smaller set:
1494  // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42
1495  // If this is or-of-compares, take the larger set:
1496  // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4
1497  if (Range0.contains(Range1))
1498  return IsAnd ? Cmp1 : Cmp0;
1499  if (Range1.contains(Range0))
1500  return IsAnd ? Cmp0 : Cmp1;
1501 
1502  return nullptr;
1503 }
1504 
1506  bool IsAnd) {
1507  ICmpInst::Predicate P0 = Cmp0->getPredicate(), P1 = Cmp1->getPredicate();
1508  if (!match(Cmp0->getOperand(1), m_Zero()) ||
1509  !match(Cmp1->getOperand(1), m_Zero()) || P0 != P1)
1510  return nullptr;
1511 
1512  if ((IsAnd && P0 != ICmpInst::ICMP_NE) || (!IsAnd && P1 != ICmpInst::ICMP_EQ))
1513  return nullptr;
1514 
1515  // We have either "(X == 0 || Y == 0)" or "(X != 0 && Y != 0)".
1516  Value *X = Cmp0->getOperand(0);
1517  Value *Y = Cmp1->getOperand(0);
1518 
1519  // If one of the compares is a masked version of a (not) null check, then
1520  // that compare implies the other, so we eliminate the other. Optionally, look
1521  // through a pointer-to-int cast to match a null check of a pointer type.
1522 
1523  // (X == 0) || (([ptrtoint] X & ?) == 0) --> ([ptrtoint] X & ?) == 0
1524  // (X == 0) || ((? & [ptrtoint] X) == 0) --> (? & [ptrtoint] X) == 0
1525  // (X != 0) && (([ptrtoint] X & ?) != 0) --> ([ptrtoint] X & ?) != 0
1526  // (X != 0) && ((? & [ptrtoint] X) != 0) --> (? & [ptrtoint] X) != 0
1527  if (match(Y, m_c_And(m_Specific(X), m_Value())) ||
1529  return Cmp1;
1530 
1531  // (([ptrtoint] Y & ?) == 0) || (Y == 0) --> ([ptrtoint] Y & ?) == 0
1532  // ((? & [ptrtoint] Y) == 0) || (Y == 0) --> (? & [ptrtoint] Y) == 0
1533  // (([ptrtoint] Y & ?) != 0) && (Y != 0) --> ([ptrtoint] Y & ?) != 0
1534  // ((? & [ptrtoint] Y) != 0) && (Y != 0) --> (? & [ptrtoint] Y) != 0
1535  if (match(X, m_c_And(m_Specific(Y), m_Value())) ||
1537  return Cmp0;
1538 
1539  return nullptr;
1540 }
1541 
1543  const InstrInfoQuery &IIQ) {
1544  // (icmp (add V, C0), C1) & (icmp V, C0)
1545  ICmpInst::Predicate Pred0, Pred1;
1546  const APInt *C0, *C1;
1547  Value *V;
1548  if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1549  return nullptr;
1550 
1551  if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1552  return nullptr;
1553 
1554  auto *AddInst = cast<OverflowingBinaryOperator>(Op0->getOperand(0));
1555  if (AddInst->getOperand(1) != Op1->getOperand(1))
1556  return nullptr;
1557 
1558  Type *ITy = Op0->getType();
1559  bool isNSW = IIQ.hasNoSignedWrap(AddInst);
1560  bool isNUW = IIQ.hasNoUnsignedWrap(AddInst);
1561 
1562  const APInt Delta = *C1 - *C0;
1563  if (C0->isStrictlyPositive()) {
1564  if (Delta == 2) {
1565  if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
1566  return getFalse(ITy);
1567  if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1568  return getFalse(ITy);
1569  }
1570  if (Delta == 1) {
1571  if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
1572  return getFalse(ITy);
1573  if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1574  return getFalse(ITy);
1575  }
1576  }
1577  if (C0->getBoolValue() && isNUW) {
1578  if (Delta == 2)
1579  if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
1580  return getFalse(ITy);
1581  if (Delta == 1)
1582  if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
1583  return getFalse(ITy);
1584  }
1585 
1586  return nullptr;
1587 }
1588 
1590  const InstrInfoQuery &IIQ) {
1591  if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true))
1592  return X;
1593  if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true))
1594  return X;
1595 
1596  if (Value *X = simplifyAndOfICmpsWithSameOperands(Op0, Op1))
1597  return X;
1598  if (Value *X = simplifyAndOfICmpsWithSameOperands(Op1, Op0))
1599  return X;
1600 
1601  if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true))
1602  return X;
1603 
1604  if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, true))
1605  return X;
1606 
1607  if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1, IIQ))
1608  return X;
1609  if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0, IIQ))
1610  return X;
1611 
1612  return nullptr;
1613 }
1614 
1616  const InstrInfoQuery &IIQ) {
1617  // (icmp (add V, C0), C1) | (icmp V, C0)
1618  ICmpInst::Predicate Pred0, Pred1;
1619  const APInt *C0, *C1;
1620  Value *V;
1621  if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1622  return nullptr;
1623 
1624  if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1625  return nullptr;
1626 
1627  auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1628  if (AddInst->getOperand(1) != Op1->getOperand(1))
1629  return nullptr;
1630 
1631  Type *ITy = Op0->getType();
1632  bool isNSW = IIQ.hasNoSignedWrap(AddInst);
1633  bool isNUW = IIQ.hasNoUnsignedWrap(AddInst);
1634 
1635  const APInt Delta = *C1 - *C0;
1636  if (C0->isStrictlyPositive()) {
1637  if (Delta == 2) {
1638  if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
1639  return getTrue(ITy);
1640  if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1641  return getTrue(ITy);
1642  }
1643  if (Delta == 1) {
1644  if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
1645  return getTrue(ITy);
1646  if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1647  return getTrue(ITy);
1648  }
1649  }
1650  if (C0->getBoolValue() && isNUW) {
1651  if (Delta == 2)
1652  if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
1653  return getTrue(ITy);
1654  if (Delta == 1)
1655  if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
1656  return getTrue(ITy);
1657  }
1658 
1659  return nullptr;
1660 }
1661 
1663  const InstrInfoQuery &IIQ) {
1664  if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false))
1665  return X;
1666  if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false))
1667  return X;
1668 
1669  if (Value *X = simplifyOrOfICmpsWithSameOperands(Op0, Op1))
1670  return X;
1671  if (Value *X = simplifyOrOfICmpsWithSameOperands(Op1, Op0))
1672  return X;
1673 
1674  if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false))
1675  return X;
1676 
1677  if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, false))
1678  return X;
1679 
1680  if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, IIQ))
1681  return X;
1682  if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, IIQ))
1683  return X;
1684 
1685  return nullptr;
1686 }
1687 
1689  FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
1690  Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
1691  Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
1692  if (LHS0->getType() != RHS0->getType())
1693  return nullptr;
1694 
1695  FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
1696  if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) ||
1697  (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) {
1698  // (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y
1699  // (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X
1700  // (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y
1701  // (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X
1702  // (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y
1703  // (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X
1704  // (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y
1705  // (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X
1706  if ((isKnownNeverNaN(LHS0, TLI) && (LHS1 == RHS0 || LHS1 == RHS1)) ||
1707  (isKnownNeverNaN(LHS1, TLI) && (LHS0 == RHS0 || LHS0 == RHS1)))
1708  return RHS;
1709 
1710  // (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y
1711  // (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X
1712  // (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y
1713  // (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X
1714  // (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y
1715  // (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X
1716  // (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y
1717  // (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X
1718  if ((isKnownNeverNaN(RHS0, TLI) && (RHS1 == LHS0 || RHS1 == LHS1)) ||
1719  (isKnownNeverNaN(RHS1, TLI) && (RHS0 == LHS0 || RHS0 == LHS1)))
1720  return LHS;
1721  }
1722 
1723  return nullptr;
1724 }
1725 
1727  Value *Op0, Value *Op1, bool IsAnd) {
1728  // Look through casts of the 'and' operands to find compares.
1729  auto *Cast0 = dyn_cast<CastInst>(Op0);
1730  auto *Cast1 = dyn_cast<CastInst>(Op1);
1731  if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() &&
1732  Cast0->getSrcTy() == Cast1->getSrcTy()) {
1733  Op0 = Cast0->getOperand(0);
1734  Op1 = Cast1->getOperand(0);
1735  }
1736 
1737  Value *V = nullptr;
1738  auto *ICmp0 = dyn_cast<ICmpInst>(Op0);
1739  auto *ICmp1 = dyn_cast<ICmpInst>(Op1);
1740  if (ICmp0 && ICmp1)
1741  V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1, Q.IIQ)
1742  : simplifyOrOfICmps(ICmp0, ICmp1, Q.IIQ);
1743 
1744  auto *FCmp0 = dyn_cast<FCmpInst>(Op0);
1745  auto *FCmp1 = dyn_cast<FCmpInst>(Op1);
1746  if (FCmp0 && FCmp1)
1747  V = simplifyAndOrOfFCmps(Q.TLI, FCmp0, FCmp1, IsAnd);
1748 
1749  if (!V)
1750  return nullptr;
1751  if (!Cast0)
1752  return V;
1753 
1754  // If we looked through casts, we can only handle a constant simplification
1755  // because we are not allowed to create a cast instruction here.
1756  if (auto *C = dyn_cast<Constant>(V))
1757  return ConstantExpr::getCast(Cast0->getOpcode(), C, Cast0->getType());
1758 
1759  return nullptr;
1760 }
1761 
1762 /// Given operands for an And, see if we can fold the result.
1763 /// If not, this returns null.
1764 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1765  unsigned MaxRecurse) {
1766  if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q))
1767  return C;
1768 
1769  // X & undef -> 0
1770  if (match(Op1, m_Undef()))
1771  return Constant::getNullValue(Op0->getType());
1772 
1773  // X & X = X
1774  if (Op0 == Op1)
1775  return Op0;
1776 
1777  // X & 0 = 0
1778  if (match(Op1, m_Zero()))
1779  return Constant::getNullValue(Op0->getType());
1780 
1781  // X & -1 = X
1782  if (match(Op1, m_AllOnes()))
1783  return Op0;
1784 
1785  // A & ~A = ~A & A = 0
1786  if (match(Op0, m_Not(m_Specific(Op1))) ||
1787  match(Op1, m_Not(m_Specific(Op0))))
1788  return Constant::getNullValue(Op0->getType());
1789 
1790  // (A | ?) & A = A
1791  if (match(Op0, m_c_Or(m_Specific(Op1), m_Value())))
1792  return Op1;
1793 
1794  // A & (A | ?) = A
1795  if (match(Op1, m_c_Or(m_Specific(Op0), m_Value())))
1796  return Op0;
1797 
1798  // A mask that only clears known zeros of a shifted value is a no-op.
1799  Value *X;
1800  const APInt *Mask;
1801  const APInt *ShAmt;
1802  if (match(Op1, m_APInt(Mask))) {
1803  // If all bits in the inverted and shifted mask are clear:
1804  // and (shl X, ShAmt), Mask --> shl X, ShAmt
1805  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) &&
1806  (~(*Mask)).lshr(*ShAmt).isNullValue())
1807  return Op0;
1808 
1809  // If all bits in the inverted and shifted mask are clear:
1810  // and (lshr X, ShAmt), Mask --> lshr X, ShAmt
1811  if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) &&
1812  (~(*Mask)).shl(*ShAmt).isNullValue())
1813  return Op0;
1814  }
1815 
1816  // A & (-A) = A if A is a power of two or zero.
1817  if (match(Op0, m_Neg(m_Specific(Op1))) ||
1818  match(Op1, m_Neg(m_Specific(Op0)))) {
1819  if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1820  Q.DT))
1821  return Op0;
1822  if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1823  Q.DT))
1824  return Op1;
1825  }
1826 
1827  // This is a similar pattern used for checking if a value is a power-of-2:
1828  // (A - 1) & A --> 0 (if A is a power-of-2 or 0)
1829  // A & (A - 1) --> 0 (if A is a power-of-2 or 0)
1830  if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) &&
1831  isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
1832  return Constant::getNullValue(Op1->getType());
1833  if (match(Op1, m_Add(m_Specific(Op0), m_AllOnes())) &&
1834  isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
1835  return Constant::getNullValue(Op0->getType());
1836 
1837  if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true))
1838  return V;
1839 
1840  // Try some generic simplifications for associative operations.
1841  if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1842  MaxRecurse))
1843  return V;
1844 
1845  // And distributes over Or. Try some generic simplifications based on this.
1846  if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1847  Q, MaxRecurse))
1848  return V;
1849 
1850  // And distributes over Xor. Try some generic simplifications based on this.
1851  if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1852  Q, MaxRecurse))
1853  return V;
1854 
1855  // If the operation is with the result of a select instruction, check whether
1856  // operating on either branch of the select always yields the same value.
1857  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1858  if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1859  MaxRecurse))
1860  return V;
1861 
1862  // If the operation is with the result of a phi instruction, check whether
1863  // operating on all incoming values of the phi always yields the same value.
1864  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1865  if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1866  MaxRecurse))
1867  return V;
1868 
1869  // Assuming the effective width of Y is not larger than A, i.e. all bits
1870  // from X and Y are disjoint in (X << A) | Y,
1871  // if the mask of this AND op covers all bits of X or Y, while it covers
1872  // no bits from the other, we can bypass this AND op. E.g.,
1873  // ((X << A) | Y) & Mask -> Y,
1874  // if Mask = ((1 << effective_width_of(Y)) - 1)
1875  // ((X << A) | Y) & Mask -> X << A,
1876  // if Mask = ((1 << effective_width_of(X)) - 1) << A
1877  // SimplifyDemandedBits in InstCombine can optimize the general case.
1878  // This pattern aims to help other passes for a common case.
1879  Value *Y, *XShifted;
1880  if (match(Op1, m_APInt(Mask)) &&
1881  match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)),
1882  m_Value(XShifted)),
1883  m_Value(Y)))) {
1884  const unsigned Width = Op0->getType()->getScalarSizeInBits();
1885  const unsigned ShftCnt = ShAmt->getLimitedValue(Width);
1886  const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1887  const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros();
1888  if (EffWidthY <= ShftCnt) {
1889  const KnownBits XKnown = computeKnownBits(X, Q.DL, 0, Q.AC, Q.CxtI,
1890  Q.DT);
1891  const unsigned EffWidthX = Width - XKnown.countMinLeadingZeros();
1892  const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY);
1893  const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt;
1894  // If the mask is extracting all bits from X or Y as is, we can skip
1895  // this AND op.
1896  if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask))
1897  return Y;
1898  if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask))
1899  return XShifted;
1900  }
1901  }
1902 
1903  return nullptr;
1904 }
1905 
1908 }
1909 
1910 /// Given operands for an Or, see if we can fold the result.
1911 /// If not, this returns null.
1912 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1913  unsigned MaxRecurse) {
1914  if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q))
1915  return C;
1916 
1917  // X | undef -> -1
1918  // X | -1 = -1
1919  // Do not return Op1 because it may contain undef elements if it's a vector.
1920  if (match(Op1, m_Undef()) || match(Op1, m_AllOnes()))
1921  return Constant::getAllOnesValue(Op0->getType());
1922 
1923  // X | X = X
1924  // X | 0 = X
1925  if (Op0 == Op1 || match(Op1, m_Zero()))
1926  return Op0;
1927 
1928  // A | ~A = ~A | A = -1
1929  if (match(Op0, m_Not(m_Specific(Op1))) ||
1930  match(Op1, m_Not(m_Specific(Op0))))
1931  return Constant::getAllOnesValue(Op0->getType());
1932 
1933  // (A & ?) | A = A
1934  if (match(Op0, m_c_And(m_Specific(Op1), m_Value())))
1935  return Op1;
1936 
1937  // A | (A & ?) = A
1938  if (match(Op1, m_c_And(m_Specific(Op0), m_Value())))
1939  return Op0;
1940 
1941  // ~(A & ?) | A = -1
1942  if (match(Op0, m_Not(m_c_And(m_Specific(Op1), m_Value()))))
1943  return Constant::getAllOnesValue(Op1->getType());
1944 
1945  // A | ~(A & ?) = -1
1946  if (match(Op1, m_Not(m_c_And(m_Specific(Op1), m_Value()))))
1947  return Constant::getAllOnesValue(Op0->getType());
1948 
1949  Value *A, *B;
1950  // (A & ~B) | (A ^ B) -> (A ^ B)
1951  // (~B & A) | (A ^ B) -> (A ^ B)
1952  // (A & ~B) | (B ^ A) -> (B ^ A)
1953  // (~B & A) | (B ^ A) -> (B ^ A)
1954  if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
1955  (match(Op0, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
1956  match(Op0, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
1957  return Op1;
1958 
1959  // Commute the 'or' operands.
1960  // (A ^ B) | (A & ~B) -> (A ^ B)
1961  // (A ^ B) | (~B & A) -> (A ^ B)
1962  // (B ^ A) | (A & ~B) -> (B ^ A)
1963  // (B ^ A) | (~B & A) -> (B ^ A)
1964  if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
1965  (match(Op1, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
1966  match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
1967  return Op0;
1968 
1969  // (A & B) | (~A ^ B) -> (~A ^ B)
1970  // (B & A) | (~A ^ B) -> (~A ^ B)
1971  // (A & B) | (B ^ ~A) -> (B ^ ~A)
1972  // (B & A) | (B ^ ~A) -> (B ^ ~A)
1973  if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1974  (match(Op1, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
1975  match(Op1, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
1976  return Op1;
1977 
1978  // (~A ^ B) | (A & B) -> (~A ^ B)
1979  // (~A ^ B) | (B & A) -> (~A ^ B)
1980  // (B ^ ~A) | (A & B) -> (B ^ ~A)
1981  // (B ^ ~A) | (B & A) -> (B ^ ~A)
1982  if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1983  (match(Op0, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
1984  match(Op0, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
1985  return Op0;
1986 
1987  if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false))
1988  return V;
1989 
1990  // Try some generic simplifications for associative operations.
1991  if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1992  MaxRecurse))
1993  return V;
1994 
1995  // Or distributes over And. Try some generic simplifications based on this.
1996  if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1997  MaxRecurse))
1998  return V;
1999 
2000  // If the operation is with the result of a select instruction, check whether
2001  // operating on either branch of the select always yields the same value.
2002  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
2003  if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
2004  MaxRecurse))
2005  return V;
2006 
2007  // (A & C1)|(B & C2)
2008  const APInt *C1, *C2;
2009  if (match(Op0, m_And(m_Value(A), m_APInt(C1))) &&
2010  match(Op1, m_And(m_Value(B), m_APInt(C2)))) {
2011  if (*C1 == ~*C2) {
2012  // (A & C1)|(B & C2)
2013  // If we have: ((V + N) & C1) | (V & C2)
2014  // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2015  // replace with V+N.
2016  Value *N;
2017  if (C2->isMask() && // C2 == 0+1+
2018  match(A, m_c_Add(m_Specific(B), m_Value(N)))) {
2019  // Add commutes, try both ways.
2020  if (MaskedValueIsZero(N, *C2, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2021  return A;
2022  }
2023  // Or commutes, try both ways.
2024  if (C1->isMask() &&
2025  match(B, m_c_Add(m_Specific(A), m_Value(N)))) {
2026  // Add commutes, try both ways.
2027  if (MaskedValueIsZero(N, *C1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2028  return B;
2029  }
2030  }
2031  }
2032 
2033  // If the operation is with the result of a phi instruction, check whether
2034  // operating on all incoming values of the phi always yields the same value.
2035  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
2036  if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
2037  return V;
2038 
2039  return nullptr;
2040 }
2041 
2044 }
2045 
2046 /// Given operands for a Xor, see if we can fold the result.
2047 /// If not, this returns null.
2048 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
2049  unsigned MaxRecurse) {
2050  if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q))
2051  return C;
2052 
2053  // A ^ undef -> undef
2054  if (match(Op1, m_Undef()))
2055  return Op1;
2056 
2057  // A ^ 0 = A
2058  if (match(Op1, m_Zero()))
2059  return Op0;
2060 
2061  // A ^ A = 0
2062  if (Op0 == Op1)
2063  return Constant::getNullValue(Op0->getType());
2064 
2065  // A ^ ~A = ~A ^ A = -1
2066  if (match(Op0, m_Not(m_Specific(Op1))) ||
2067  match(Op1, m_Not(m_Specific(Op0))))
2068  return Constant::getAllOnesValue(Op0->getType());
2069 
2070  // Try some generic simplifications for associative operations.
2071  if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
2072  MaxRecurse))
2073  return V;
2074 
2075  // Threading Xor over selects and phi nodes is pointless, so don't bother.
2076  // Threading over the select in "A ^ select(cond, B, C)" means evaluating
2077  // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
2078  // only if B and C are equal. If B and C are equal then (since we assume
2079  // that operands have already been simplified) "select(cond, B, C)" should
2080  // have been simplified to the common value of B and C already. Analysing
2081  // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
2082  // for threading over phi nodes.
2083 
2084  return nullptr;
2085 }
2086 
2089 }
2090 
2091 
2093  return CmpInst::makeCmpResultType(Op->getType());
2094 }
2095 
2096 /// Rummage around inside V looking for something equivalent to the comparison
2097 /// "LHS Pred RHS". Return such a value if found, otherwise return null.
2098 /// Helper function for analyzing max/min idioms.
2100  Value *LHS, Value *RHS) {
2102  if (!SI)
2103  return nullptr;
2104  CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
2105  if (!Cmp)
2106  return nullptr;
2107  Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
2108  if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
2109  return Cmp;
2110  if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
2111  LHS == CmpRHS && RHS == CmpLHS)
2112  return Cmp;
2113  return nullptr;
2114 }
2115 
2116 // A significant optimization not implemented here is assuming that alloca
2117 // addresses are not equal to incoming argument values. They don't *alias*,
2118 // as we say, but that doesn't mean they aren't equal, so we take a
2119 // conservative approach.
2120 //
2121 // This is inspired in part by C++11 5.10p1:
2122 // "Two pointers of the same type compare equal if and only if they are both
2123 // null, both point to the same function, or both represent the same
2124 // address."
2125 //
2126 // This is pretty permissive.
2127 //
2128 // It's also partly due to C11 6.5.9p6:
2129 // "Two pointers compare equal if and only if both are null pointers, both are
2130 // pointers to the same object (including a pointer to an object and a
2131 // subobject at its beginning) or function, both are pointers to one past the
2132 // last element of the same array object, or one is a pointer to one past the
2133 // end of one array object and the other is a pointer to the start of a
2134 // different array object that happens to immediately follow the first array
2135 // object in the address space.)
2136 //
2137 // C11's version is more restrictive, however there's no reason why an argument
2138 // couldn't be a one-past-the-end value for a stack object in the caller and be
2139 // equal to the beginning of a stack object in the callee.
2140 //
2141 // If the C and C++ standards are ever made sufficiently restrictive in this
2142 // area, it may be possible to update LLVM's semantics accordingly and reinstate
2143 // this optimization.
2144 static Constant *
2146  const DominatorTree *DT, CmpInst::Predicate Pred,
2147  AssumptionCache *AC, const Instruction *CxtI,
2148  const InstrInfoQuery &IIQ, Value *LHS, Value *RHS) {
2149  // First, skip past any trivial no-ops.
2150  LHS = LHS->stripPointerCasts();
2151  RHS = RHS->stripPointerCasts();
2152 
2153  // A non-null pointer is not equal to a null pointer.
2154  if (llvm::isKnownNonZero(LHS, DL, 0, nullptr, nullptr, nullptr,
2155  IIQ.UseInstrInfo) &&
2156  isa<ConstantPointerNull>(RHS) &&
2157  (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE))
2158  return ConstantInt::get(GetCompareTy(LHS),
2159  !CmpInst::isTrueWhenEqual(Pred));
2160 
2161  // We can only fold certain predicates on pointer comparisons.
2162  switch (Pred) {
2163  default:
2164  return nullptr;
2165 
2166  // Equality comaprisons are easy to fold.
2167  case CmpInst::ICMP_EQ:
2168  case CmpInst::ICMP_NE:
2169  break;
2170 
2171  // We can only handle unsigned relational comparisons because 'inbounds' on
2172  // a GEP only protects against unsigned wrapping.
2173  case CmpInst::ICMP_UGT:
2174  case CmpInst::ICMP_UGE:
2175  case CmpInst::ICMP_ULT:
2176  case CmpInst::ICMP_ULE:
2177  // However, we have to switch them to their signed variants to handle
2178  // negative indices from the base pointer.
2179  Pred = ICmpInst::getSignedPredicate(Pred);
2180  break;
2181  }
2182 
2183  // Strip off any constant offsets so that we can reason about them.
2184  // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
2185  // here and compare base addresses like AliasAnalysis does, however there are
2186  // numerous hazards. AliasAnalysis and its utilities rely on special rules
2187  // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
2188  // doesn't need to guarantee pointer inequality when it says NoAlias.
2189  Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
2190  Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
2191 
2192  // If LHS and RHS are related via constant offsets to the same base
2193  // value, we can replace it with an icmp which just compares the offsets.
2194  if (LHS == RHS)
2195  return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
2196 
2197  // Various optimizations for (in)equality comparisons.
2198  if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
2199  // Different non-empty allocations that exist at the same time have
2200  // different addresses (if the program can tell). Global variables always
2201  // exist, so they always exist during the lifetime of each other and all
2202  // allocas. Two different allocas usually have different addresses...
2203  //
2204  // However, if there's an @llvm.stackrestore dynamically in between two
2205  // allocas, they may have the same address. It's tempting to reduce the
2206  // scope of the problem by only looking at *static* allocas here. That would
2207  // cover the majority of allocas while significantly reducing the likelihood
2208  // of having an @llvm.stackrestore pop up in the middle. However, it's not
2209  // actually impossible for an @llvm.stackrestore to pop up in the middle of
2210  // an entry block. Also, if we have a block that's not attached to a
2211  // function, we can't tell if it's "static" under the current definition.
2212  // Theoretically, this problem could be fixed by creating a new kind of
2213  // instruction kind specifically for static allocas. Such a new instruction
2214  // could be required to be at the top of the entry block, thus preventing it
2215  // from being subject to a @llvm.stackrestore. Instcombine could even
2216  // convert regular allocas into these special allocas. It'd be nifty.
2217  // However, until then, this problem remains open.
2218  //
2219  // So, we'll assume that two non-empty allocas have different addresses
2220  // for now.
2221  //
2222  // With all that, if the offsets are within the bounds of their allocations
2223  // (and not one-past-the-end! so we can't use inbounds!), and their
2224  // allocations aren't the same, the pointers are not equal.
2225  //
2226  // Note that it's not necessary to check for LHS being a global variable
2227  // address, due to canonicalization and constant folding.
2228  if (isa<AllocaInst>(LHS) &&
2229  (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
2230  ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
2231  ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
2232  uint64_t LHSSize, RHSSize;
2233  ObjectSizeOpts Opts;
2234  Opts.NullIsUnknownSize =
2235  NullPointerIsDefined(cast<AllocaInst>(LHS)->getFunction());
2236  if (LHSOffsetCI && RHSOffsetCI &&
2237  getObjectSize(LHS, LHSSize, DL, TLI, Opts) &&
2238  getObjectSize(RHS, RHSSize, DL, TLI, Opts)) {
2239  const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
2240  const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
2241  if (!LHSOffsetValue.isNegative() &&
2242  !RHSOffsetValue.isNegative() &&
2243  LHSOffsetValue.ult(LHSSize) &&
2244  RHSOffsetValue.ult(RHSSize)) {
2245  return ConstantInt::get(GetCompareTy(LHS),
2246  !CmpInst::isTrueWhenEqual(Pred));
2247  }
2248  }
2249 
2250  // Repeat the above check but this time without depending on DataLayout
2251  // or being able to compute a precise size.
2252  if (!cast<PointerType>(LHS->getType())->isEmptyTy() &&
2253  !cast<PointerType>(RHS->getType())->isEmptyTy() &&
2254  LHSOffset->isNullValue() &&
2255  RHSOffset->isNullValue())
2256  return ConstantInt::get(GetCompareTy(LHS),
2257  !CmpInst::isTrueWhenEqual(Pred));
2258  }
2259 
2260  // Even if an non-inbounds GEP occurs along the path we can still optimize
2261  // equality comparisons concerning the result. We avoid walking the whole
2262  // chain again by starting where the last calls to
2263  // stripAndComputeConstantOffsets left off and accumulate the offsets.
2264  Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true);
2265  Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true);
2266  if (LHS == RHS)
2267  return ConstantExpr::getICmp(Pred,
2268  ConstantExpr::getAdd(LHSOffset, LHSNoBound),
2269  ConstantExpr::getAdd(RHSOffset, RHSNoBound));
2270 
2271  // If one side of the equality comparison must come from a noalias call
2272  // (meaning a system memory allocation function), and the other side must
2273  // come from a pointer that cannot overlap with dynamically-allocated
2274  // memory within the lifetime of the current function (allocas, byval
2275  // arguments, globals), then determine the comparison result here.
2276  SmallVector<const Value *, 8> LHSUObjs, RHSUObjs;
2277  GetUnderlyingObjects(LHS, LHSUObjs, DL);
2278  GetUnderlyingObjects(RHS, RHSUObjs, DL);
2279 
2280  // Is the set of underlying objects all noalias calls?
2281  auto IsNAC = [](ArrayRef<const Value *> Objects) {
2282  return all_of(Objects, isNoAliasCall);
2283  };
2284 
2285  // Is the set of underlying objects all things which must be disjoint from
2286  // noalias calls. For allocas, we consider only static ones (dynamic
2287  // allocas might be transformed into calls to malloc not simultaneously
2288  // live with the compared-to allocation). For globals, we exclude symbols
2289  // that might be resolve lazily to symbols in another dynamically-loaded
2290  // library (and, thus, could be malloc'ed by the implementation).
2291  auto IsAllocDisjoint = [](ArrayRef<const Value *> Objects) {
2292  return all_of(Objects, [](const Value *V) {
2293  if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
2294  return AI->getParent() && AI->getFunction() && AI->isStaticAlloca();
2295  if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
2296  return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() ||
2297  GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) &&
2298  !GV->isThreadLocal();
2299  if (const Argument *A = dyn_cast<Argument>(V))
2300  return A->hasByValAttr();
2301  return false;
2302  });
2303  };
2304 
2305  if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
2306  (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
2307  return ConstantInt::get(GetCompareTy(LHS),
2308  !CmpInst::isTrueWhenEqual(Pred));
2309 
2310  // Fold comparisons for non-escaping pointer even if the allocation call
2311  // cannot be elided. We cannot fold malloc comparison to null. Also, the
2312  // dynamic allocation call could be either of the operands.
2313  Value *MI = nullptr;
2314  if (isAllocLikeFn(LHS, TLI) &&
2315  llvm::isKnownNonZero(RHS, DL, 0, nullptr, CxtI, DT))
2316  MI = LHS;
2317  else if (isAllocLikeFn(RHS, TLI) &&
2318  llvm::isKnownNonZero(LHS, DL, 0, nullptr, CxtI, DT))
2319  MI = RHS;
2320  // FIXME: We should also fold the compare when the pointer escapes, but the
2321  // compare dominates the pointer escape
2322  if (MI && !PointerMayBeCaptured(MI, true, true))
2323  return ConstantInt::get(GetCompareTy(LHS),
2325  }
2326 
2327  // Otherwise, fail.
2328  return nullptr;
2329 }
2330 
2331 /// Fold an icmp when its operands have i1 scalar type.
2333  Value *RHS, const SimplifyQuery &Q) {
2334  Type *ITy = GetCompareTy(LHS); // The return type.
2335  Type *OpTy = LHS->getType(); // The operand type.
2336  if (!OpTy->isIntOrIntVectorTy(1))
2337  return nullptr;
2338 
2339  // A boolean compared to true/false can be simplified in 14 out of the 20
2340  // (10 predicates * 2 constants) possible combinations. Cases not handled here
2341  // require a 'not' of the LHS, so those must be transformed in InstCombine.
2342  if (match(RHS, m_Zero())) {
2343  switch (Pred) {
2344  case CmpInst::ICMP_NE: // X != 0 -> X
2345  case CmpInst::ICMP_UGT: // X >u 0 -> X
2346  case CmpInst::ICMP_SLT: // X <s 0 -> X
2347  return LHS;
2348 
2349  case CmpInst::ICMP_ULT: // X <u 0 -> false
2350  case CmpInst::ICMP_SGT: // X >s 0 -> false
2351  return getFalse(ITy);
2352 
2353  case CmpInst::ICMP_UGE: // X >=u 0 -> true
2354  case CmpInst::ICMP_SLE: // X <=s 0 -> true
2355  return getTrue(ITy);
2356 
2357  default: break;
2358  }
2359  } else if (match(RHS, m_One())) {
2360  switch (Pred) {
2361  case CmpInst::ICMP_EQ: // X == 1 -> X
2362  case CmpInst::ICMP_UGE: // X >=u 1 -> X
2363  case CmpInst::ICMP_SLE: // X <=s -1 -> X
2364  return LHS;
2365 
2366  case CmpInst::ICMP_UGT: // X >u 1 -> false
2367  case CmpInst::ICMP_SLT: // X <s -1 -> false
2368  return getFalse(ITy);
2369 
2370  case CmpInst::ICMP_ULE: // X <=u 1 -> true
2371  case CmpInst::ICMP_SGE: // X >=s -1 -> true
2372  return getTrue(ITy);
2373 
2374  default: break;
2375  }
2376  }
2377 
2378  switch (Pred) {
2379  default:
2380  break;
2381  case ICmpInst::ICMP_UGE:
2382  if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
2383  return getTrue(ITy);
2384  break;
2385  case ICmpInst::ICMP_SGE:
2386  /// For signed comparison, the values for an i1 are 0 and -1
2387  /// respectively. This maps into a truth table of:
2388  /// LHS | RHS | LHS >=s RHS | LHS implies RHS
2389  /// 0 | 0 | 1 (0 >= 0) | 1
2390  /// 0 | 1 | 1 (0 >= -1) | 1
2391  /// 1 | 0 | 0 (-1 >= 0) | 0
2392  /// 1 | 1 | 1 (-1 >= -1) | 1
2393  if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
2394  return getTrue(ITy);
2395  break;
2396  case ICmpInst::ICMP_ULE:
2397  if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
2398  return getTrue(ITy);
2399  break;
2400  }
2401 
2402  return nullptr;
2403 }
2404 
2405 /// Try hard to fold icmp with zero RHS because this is a common case.
2407  Value *RHS, const SimplifyQuery &Q) {
2408  if (!match(RHS, m_Zero()))
2409  return nullptr;
2410 
2411  Type *ITy = GetCompareTy(LHS); // The return type.
2412  switch (Pred) {
2413  default:
2414  llvm_unreachable("Unknown ICmp predicate!");
2415  case ICmpInst::ICMP_ULT:
2416  return getFalse(ITy);
2417  case ICmpInst::ICMP_UGE:
2418  return getTrue(ITy);
2419  case ICmpInst::ICMP_EQ:
2420  case ICmpInst::ICMP_ULE:
2421  if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo))
2422  return getFalse(ITy);
2423  break;
2424  case ICmpInst::ICMP_NE:
2425  case ICmpInst::ICMP_UGT:
2426  if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo))
2427  return getTrue(ITy);
2428  break;
2429  case ICmpInst::ICMP_SLT: {
2430  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2431  if (LHSKnown.isNegative())
2432  return getTrue(ITy);
2433  if (LHSKnown.isNonNegative())
2434  return getFalse(ITy);
2435  break;
2436  }
2437  case ICmpInst::ICMP_SLE: {
2438  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2439  if (LHSKnown.isNegative())
2440  return getTrue(ITy);
2441  if (LHSKnown.isNonNegative() &&
2442  isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2443  return getFalse(ITy);
2444  break;
2445  }
2446  case ICmpInst::ICMP_SGE: {
2447  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2448  if (LHSKnown.isNegative())
2449  return getFalse(ITy);
2450  if (LHSKnown.isNonNegative())
2451  return getTrue(ITy);
2452  break;
2453  }
2454  case ICmpInst::ICMP_SGT: {
2455  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2456  if (LHSKnown.isNegative())
2457  return getFalse(ITy);
2458  if (LHSKnown.isNonNegative() &&
2459  isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2460  return getTrue(ITy);
2461  break;
2462  }
2463  }
2464 
2465  return nullptr;
2466 }
2467 
2469  Value *RHS, const InstrInfoQuery &IIQ) {
2470  Type *ITy = GetCompareTy(RHS); // The return type.
2471 
2472  Value *X;
2473  // Sign-bit checks can be optimized to true/false after unsigned
2474  // floating-point casts:
2475  // icmp slt (bitcast (uitofp X)), 0 --> false
2476  // icmp sgt (bitcast (uitofp X)), -1 --> true
2477  if (match(LHS, m_BitCast(m_UIToFP(m_Value(X))))) {
2478  if (Pred == ICmpInst::ICMP_SLT && match(RHS, m_Zero()))
2479  return ConstantInt::getFalse(ITy);
2480  if (Pred == ICmpInst::ICMP_SGT && match(RHS, m_AllOnes()))
2481  return ConstantInt::getTrue(ITy);
2482  }
2483 
2484  const APInt *C;
2485  if (!match(RHS, m_APInt(C)))
2486  return nullptr;
2487 
2488  // Rule out tautological comparisons (eg., ult 0 or uge 0).
2490  if (RHS_CR.isEmptySet())
2491  return ConstantInt::getFalse(ITy);
2492  if (RHS_CR.isFullSet())
2493  return ConstantInt::getTrue(ITy);
2494 
2495  ConstantRange LHS_CR = computeConstantRange(LHS, IIQ.UseInstrInfo);
2496  if (!LHS_CR.isFullSet()) {
2497  if (RHS_CR.contains(LHS_CR))
2498  return ConstantInt::getTrue(ITy);
2499  if (RHS_CR.inverse().contains(LHS_CR))
2500  return ConstantInt::getFalse(ITy);
2501  }
2502 
2503  return nullptr;
2504 }
2505 
2506 /// TODO: A large part of this logic is duplicated in InstCombine's
2507 /// foldICmpBinOp(). We should be able to share that and avoid the code
2508 /// duplication.
2510  Value *RHS, const SimplifyQuery &Q,
2511  unsigned MaxRecurse) {
2512  Type *ITy = GetCompareTy(LHS); // The return type.
2513 
2514  BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2515  BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2516  if (MaxRecurse && (LBO || RBO)) {
2517  // Analyze the case when either LHS or RHS is an add instruction.
2518  Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2519  // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2520  bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2521  if (LBO && LBO->getOpcode() == Instruction::Add) {
2522  A = LBO->getOperand(0);
2523  B = LBO->getOperand(1);
2524  NoLHSWrapProblem =
2525  ICmpInst::isEquality(Pred) ||
2526  (CmpInst::isUnsigned(Pred) &&
2527  Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO))) ||
2528  (CmpInst::isSigned(Pred) &&
2529  Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)));
2530  }
2531  if (RBO && RBO->getOpcode() == Instruction::Add) {
2532  C = RBO->getOperand(0);
2533  D = RBO->getOperand(1);
2534  NoRHSWrapProblem =
2535  ICmpInst::isEquality(Pred) ||
2536  (CmpInst::isUnsigned(Pred) &&
2537  Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(RBO))) ||
2538  (CmpInst::isSigned(Pred) &&
2539  Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RBO)));
2540  }
2541 
2542  // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2543  if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2544  if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2545  Constant::getNullValue(RHS->getType()), Q,
2546  MaxRecurse - 1))
2547  return V;
2548 
2549  // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2550  if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2551  if (Value *V =
2553  C == LHS ? D : C, Q, MaxRecurse - 1))
2554  return V;
2555 
2556  // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2557  if (A && C && (A == C || A == D || B == C || B == D) && NoLHSWrapProblem &&
2558  NoRHSWrapProblem) {
2559  // Determine Y and Z in the form icmp (X+Y), (X+Z).
2560  Value *Y, *Z;
2561  if (A == C) {
2562  // C + B == C + D -> B == D
2563  Y = B;
2564  Z = D;
2565  } else if (A == D) {
2566  // D + B == C + D -> B == C
2567  Y = B;
2568  Z = C;
2569  } else if (B == C) {
2570  // A + C == C + D -> A == D
2571  Y = A;
2572  Z = D;
2573  } else {
2574  assert(B == D);
2575  // A + D == C + D -> A == C
2576  Y = A;
2577  Z = C;
2578  }
2579  if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1))
2580  return V;
2581  }
2582  }
2583 
2584  {
2585  Value *Y = nullptr;
2586  // icmp pred (or X, Y), X
2587  if (LBO && match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) {
2588  if (Pred == ICmpInst::ICMP_ULT)
2589  return getFalse(ITy);
2590  if (Pred == ICmpInst::ICMP_UGE)
2591  return getTrue(ITy);
2592 
2593  if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) {
2594  KnownBits RHSKnown = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2595  KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2596  if (RHSKnown.isNonNegative() && YKnown.isNegative())
2597  return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy);
2598  if (RHSKnown.isNegative() || YKnown.isNonNegative())
2599  return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy);
2600  }
2601  }
2602  // icmp pred X, (or X, Y)
2603  if (RBO && match(RBO, m_c_Or(m_Value(Y), m_Specific(LHS)))) {
2604  if (Pred == ICmpInst::ICMP_ULE)
2605  return getTrue(ITy);
2606  if (Pred == ICmpInst::ICMP_UGT)
2607  return getFalse(ITy);
2608 
2609  if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLE) {
2610  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2611  KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2612  if (LHSKnown.isNonNegative() && YKnown.isNegative())
2613  return Pred == ICmpInst::ICMP_SGT ? getTrue(ITy) : getFalse(ITy);
2614  if (LHSKnown.isNegative() || YKnown.isNonNegative())
2615  return Pred == ICmpInst::ICMP_SGT ? getFalse(ITy) : getTrue(ITy);
2616  }
2617  }
2618  }
2619 
2620  // icmp pred (and X, Y), X
2621  if (LBO && match(LBO, m_c_And(m_Value(), m_Specific(RHS)))) {
2622  if (Pred == ICmpInst::ICMP_UGT)
2623  return getFalse(ITy);
2624  if (Pred == ICmpInst::ICMP_ULE)
2625  return getTrue(ITy);
2626  }
2627  // icmp pred X, (and X, Y)
2628  if (RBO && match(RBO, m_c_And(m_Value(), m_Specific(LHS)))) {
2629  if (Pred == ICmpInst::ICMP_UGE)
2630  return getTrue(ITy);
2631  if (Pred == ICmpInst::ICMP_ULT)
2632  return getFalse(ITy);
2633  }
2634 
2635  // 0 - (zext X) pred C
2636  if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
2637  if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
2638  if (RHSC->getValue().isStrictlyPositive()) {
2639  if (Pred == ICmpInst::ICMP_SLT)
2640  return ConstantInt::getTrue(RHSC->getContext());
2641  if (Pred == ICmpInst::ICMP_SGE)
2642  return ConstantInt::getFalse(RHSC->getContext());
2643  if (Pred == ICmpInst::ICMP_EQ)
2644  return ConstantInt::getFalse(RHSC->getContext());
2645  if (Pred == ICmpInst::ICMP_NE)
2646  return ConstantInt::getTrue(RHSC->getContext());
2647  }
2648  if (RHSC->getValue().isNonNegative()) {
2649  if (Pred == ICmpInst::ICMP_SLE)
2650  return ConstantInt::getTrue(RHSC->getContext());
2651  if (Pred == ICmpInst::ICMP_SGT)
2652  return ConstantInt::getFalse(RHSC->getContext());
2653  }
2654  }
2655  }
2656 
2657  // icmp pred (urem X, Y), Y
2658  if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2659  switch (Pred) {
2660  default:
2661  break;
2662  case ICmpInst::ICMP_SGT:
2663  case ICmpInst::ICMP_SGE: {
2664  KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2665  if (!Known.isNonNegative())
2666  break;
2668  }
2669  case ICmpInst::ICMP_EQ:
2670  case ICmpInst::ICMP_UGT:
2671  case ICmpInst::ICMP_UGE:
2672  return getFalse(ITy);
2673  case ICmpInst::ICMP_SLT:
2674  case ICmpInst::ICMP_SLE: {
2675  KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2676  if (!Known.isNonNegative())
2677  break;
2679  }
2680  case ICmpInst::ICMP_NE:
2681  case ICmpInst::ICMP_ULT:
2682  case ICmpInst::ICMP_ULE:
2683  return getTrue(ITy);
2684  }
2685  }
2686 
2687  // icmp pred X, (urem Y, X)
2688  if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2689  switch (Pred) {
2690  default:
2691  break;
2692  case ICmpInst::ICMP_SGT:
2693  case ICmpInst::ICMP_SGE: {
2694  KnownBits Known = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2695  if (!Known.isNonNegative())
2696  break;
2698  }
2699  case ICmpInst::ICMP_NE:
2700  case ICmpInst::ICMP_UGT:
2701  case ICmpInst::ICMP_UGE:
2702  return getTrue(ITy);
2703  case ICmpInst::ICMP_SLT:
2704  case ICmpInst::ICMP_SLE: {
2705  KnownBits Known = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2706  if (!Known.isNonNegative())
2707  break;
2709  }
2710  case ICmpInst::ICMP_EQ:
2711  case ICmpInst::ICMP_ULT:
2712  case ICmpInst::ICMP_ULE:
2713  return getFalse(ITy);
2714  }
2715  }
2716 
2717  // x >> y <=u x
2718  // x udiv y <=u x.
2719  if (LBO && (match(LBO, m_LShr(m_Specific(RHS), m_Value())) ||
2720  match(LBO, m_UDiv(m_Specific(RHS), m_Value())))) {
2721  // icmp pred (X op Y), X
2722  if (Pred == ICmpInst::ICMP_UGT)
2723  return getFalse(ITy);
2724  if (Pred == ICmpInst::ICMP_ULE)
2725  return getTrue(ITy);
2726  }
2727 
2728  // x >=u x >> y
2729  // x >=u x udiv y.
2730  if (RBO && (match(RBO, m_LShr(m_Specific(LHS), m_Value())) ||
2731  match(RBO, m_UDiv(m_Specific(LHS), m_Value())))) {
2732  // icmp pred X, (X op Y)
2733  if (Pred == ICmpInst::ICMP_ULT)
2734  return getFalse(ITy);
2735  if (Pred == ICmpInst::ICMP_UGE)
2736  return getTrue(ITy);
2737  }
2738 
2739  // handle:
2740  // CI2 << X == CI
2741  // CI2 << X != CI
2742  //
2743  // where CI2 is a power of 2 and CI isn't
2744  if (auto *CI = dyn_cast<ConstantInt>(RHS)) {
2745  const APInt *CI2Val, *CIVal = &CI->getValue();
2746  if (LBO && match(LBO, m_Shl(m_APInt(CI2Val), m_Value())) &&
2747  CI2Val->isPowerOf2()) {
2748  if (!CIVal->isPowerOf2()) {
2749  // CI2 << X can equal zero in some circumstances,
2750  // this simplification is unsafe if CI is zero.
2751  //
2752  // We know it is safe if:
2753  // - The shift is nsw, we can't shift out the one bit.
2754  // - The shift is nuw, we can't shift out the one bit.
2755  // - CI2 is one
2756  // - CI isn't zero
2757  if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) ||
2758  Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) ||
2759  CI2Val->isOneValue() || !CI->isZero()) {
2760  if (Pred == ICmpInst::ICMP_EQ)
2761  return ConstantInt::getFalse(RHS->getContext());
2762  if (Pred == ICmpInst::ICMP_NE)
2763  return ConstantInt::getTrue(RHS->getContext());
2764  }
2765  }
2766  if (CIVal->isSignMask() && CI2Val->isOneValue()) {
2767  if (Pred == ICmpInst::ICMP_UGT)
2768  return ConstantInt::getFalse(RHS->getContext());
2769  if (Pred == ICmpInst::ICMP_ULE)
2770  return ConstantInt::getTrue(RHS->getContext());
2771  }
2772  }
2773  }
2774 
2775  if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2776  LBO->getOperand(1) == RBO->getOperand(1)) {
2777  switch (LBO->getOpcode()) {
2778  default:
2779  break;
2780  case Instruction::UDiv:
2781  case Instruction::LShr:
2782  if (ICmpInst::isSigned(Pred) || !Q.IIQ.isExact(LBO) ||
2783  !Q.IIQ.isExact(RBO))
2784  break;
2785  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2786  RBO->getOperand(0), Q, MaxRecurse - 1))
2787  return V;
2788  break;
2789  case Instruction::SDiv:
2790  if (!ICmpInst::isEquality(Pred) || !Q.IIQ.isExact(LBO) ||
2791  !Q.IIQ.isExact(RBO))
2792  break;
2793  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2794  RBO->getOperand(0), Q, MaxRecurse - 1))
2795  return V;
2796  break;
2797  case Instruction::AShr:
2798  if (!Q.IIQ.isExact(LBO) || !Q.IIQ.isExact(RBO))
2799  break;
2800  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2801  RBO->getOperand(0), Q, MaxRecurse - 1))
2802  return V;
2803  break;
2804  case Instruction::Shl: {
2805  bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO);
2806  bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO);
2807  if (!NUW && !NSW)
2808  break;
2809  if (!NSW && ICmpInst::isSigned(Pred))
2810  break;
2811  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2812  RBO->getOperand(0), Q, MaxRecurse - 1))
2813  return V;
2814  break;
2815  }
2816  }
2817  }
2818  return nullptr;
2819 }
2820 
2821 /// Simplify integer comparisons where at least one operand of the compare
2822 /// matches an integer min/max idiom.
2824  Value *RHS, const SimplifyQuery &Q,
2825  unsigned MaxRecurse) {
2826  Type *ITy = GetCompareTy(LHS); // The return type.
2827  Value *A, *B;
2829  CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2830 
2831  // Signed variants on "max(a,b)>=a -> true".
2832  if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2833  if (A != RHS)
2834  std::swap(A, B); // smax(A, B) pred A.
2835  EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2836  // We analyze this as smax(A, B) pred A.
2837  P = Pred;
2838  } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2839  (A == LHS || B == LHS)) {
2840  if (A != LHS)
2841  std::swap(A, B); // A pred smax(A, B).
2842  EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2843  // We analyze this as smax(A, B) swapped-pred A.
2844  P = CmpInst::getSwappedPredicate(Pred);
2845  } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2846  (A == RHS || B == RHS)) {
2847  if (A != RHS)
2848  std::swap(A, B); // smin(A, B) pred A.
2849  EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2850  // We analyze this as smax(-A, -B) swapped-pred -A.
2851  // Note that we do not need to actually form -A or -B thanks to EqP.
2852  P = CmpInst::getSwappedPredicate(Pred);
2853  } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2854  (A == LHS || B == LHS)) {
2855  if (A != LHS)
2856  std::swap(A, B); // A pred smin(A, B).
2857  EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2858  // We analyze this as smax(-A, -B) pred -A.
2859  // Note that we do not need to actually form -A or -B thanks to EqP.
2860  P = Pred;
2861  }
2862  if (P != CmpInst::BAD_ICMP_PREDICATE) {
2863  // Cases correspond to "max(A, B) p A".
2864  switch (P) {
2865  default:
2866  break;
2867  case CmpInst::ICMP_EQ:
2868  case CmpInst::ICMP_SLE:
2869  // Equivalent to "A EqP B". This may be the same as the condition tested
2870  // in the max/min; if so, we can just return that.
2871  if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2872  return V;
2873  if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2874  return V;
2875  // Otherwise, see if "A EqP B" simplifies.
2876  if (MaxRecurse)
2877  if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
2878  return V;
2879  break;
2880  case CmpInst::ICMP_NE:
2881  case CmpInst::ICMP_SGT: {
2883  // Equivalent to "A InvEqP B". This may be the same as the condition
2884  // tested in the max/min; if so, we can just return that.
2885  if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2886  return V;
2887  if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2888  return V;
2889  // Otherwise, see if "A InvEqP B" simplifies.
2890  if (MaxRecurse)
2891  if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
2892  return V;
2893  break;
2894  }
2895  case CmpInst::ICMP_SGE:
2896  // Always true.
2897  return getTrue(ITy);
2898  case CmpInst::ICMP_SLT:
2899  // Always false.
2900  return getFalse(ITy);
2901  }
2902  }
2903 
2904  // Unsigned variants on "max(a,b)>=a -> true".
2906  if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2907  if (A != RHS)
2908  std::swap(A, B); // umax(A, B) pred A.
2909  EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2910  // We analyze this as umax(A, B) pred A.
2911  P = Pred;
2912  } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2913  (A == LHS || B == LHS)) {
2914  if (A != LHS)
2915  std::swap(A, B); // A pred umax(A, B).
2916  EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2917  // We analyze this as umax(A, B) swapped-pred A.
2918  P = CmpInst::getSwappedPredicate(Pred);
2919  } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2920  (A == RHS || B == RHS)) {
2921  if (A != RHS)
2922  std::swap(A, B); // umin(A, B) pred A.
2923  EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2924  // We analyze this as umax(-A, -B) swapped-pred -A.
2925  // Note that we do not need to actually form -A or -B thanks to EqP.
2926  P = CmpInst::getSwappedPredicate(Pred);
2927  } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2928  (A == LHS || B == LHS)) {
2929  if (A != LHS)
2930  std::swap(A, B); // A pred umin(A, B).
2931  EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2932  // We analyze this as umax(-A, -B) pred -A.
2933  // Note that we do not need to actually form -A or -B thanks to EqP.
2934  P = Pred;
2935  }
2936  if (P != CmpInst::BAD_ICMP_PREDICATE) {
2937  // Cases correspond to "max(A, B) p A".
2938  switch (P) {
2939  default:
2940  break;
2941  case CmpInst::ICMP_EQ:
2942  case CmpInst::ICMP_ULE:
2943  // Equivalent to "A EqP B". This may be the same as the condition tested
2944  // in the max/min; if so, we can just return that.
2945  if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2946  return V;
2947  if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2948  return V;
2949  // Otherwise, see if "A EqP B" simplifies.
2950  if (MaxRecurse)
2951  if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
2952  return V;
2953  break;
2954  case CmpInst::ICMP_NE:
2955  case CmpInst::ICMP_UGT: {
2957  // Equivalent to "A InvEqP B". This may be the same as the condition
2958  // tested in the max/min; if so, we can just return that.
2959  if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2960  return V;
2961  if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2962  return V;
2963  // Otherwise, see if "A InvEqP B" simplifies.
2964  if (MaxRecurse)
2965  if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
2966  return V;
2967  break;
2968  }
2969  case CmpInst::ICMP_UGE:
2970  // Always true.
2971  return getTrue(ITy);
2972  case CmpInst::ICMP_ULT:
2973  // Always false.
2974  return getFalse(ITy);
2975  }
2976  }
2977 
2978  // Variants on "max(x,y) >= min(x,z)".
2979  Value *C, *D;
2980  if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2981  match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2982  (A == C || A == D || B == C || B == D)) {
2983  // max(x, ?) pred min(x, ?).
2984  if (Pred == CmpInst::ICMP_SGE)
2985  // Always true.
2986  return getTrue(ITy);
2987  if (Pred == CmpInst::ICMP_SLT)
2988  // Always false.
2989  return getFalse(ITy);
2990  } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2991  match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2992  (A == C || A == D || B == C || B == D)) {
2993  // min(x, ?) pred max(x, ?).
2994  if (Pred == CmpInst::ICMP_SLE)
2995  // Always true.
2996  return getTrue(ITy);
2997  if (Pred == CmpInst::ICMP_SGT)
2998  // Always false.
2999  return getFalse(ITy);
3000  } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
3001  match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
3002  (A == C || A == D || B == C || B == D)) {
3003  // max(x, ?) pred min(x, ?).
3004  if (Pred == CmpInst::ICMP_UGE)
3005  // Always true.
3006  return getTrue(ITy);
3007  if (Pred == CmpInst::ICMP_ULT)
3008  // Always false.
3009  return getFalse(ITy);
3010  } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
3011  match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
3012  (A == C || A == D || B == C || B == D)) {
3013  // min(x, ?) pred max(x, ?).
3014  if (Pred == CmpInst::ICMP_ULE)
3015  // Always true.
3016  return getTrue(ITy);
3017  if (Pred == CmpInst::ICMP_UGT)
3018  // Always false.
3019  return getFalse(ITy);
3020  }
3021 
3022  return nullptr;
3023 }
3024 
3025 /// Given operands for an ICmpInst, see if we can fold the result.
3026 /// If not, this returns null.
3027 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3028  const SimplifyQuery &Q, unsigned MaxRecurse) {
3029  CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3030  assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
3031 
3032  if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3033  if (Constant *CRHS = dyn_cast<Constant>(RHS))
3034  return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3035 
3036  // If we have a constant, make sure it is on the RHS.
3037  std::swap(LHS, RHS);
3038  Pred = CmpInst::getSwappedPredicate(Pred);
3039  }
3040  assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X");
3041 
3042  Type *ITy = GetCompareTy(LHS); // The return type.
3043 
3044  // For EQ and NE, we can always pick a value for the undef to make the
3045  // predicate pass or fail, so we can return undef.
3046  // Matches behavior in llvm::ConstantFoldCompareInstruction.
3047  if (isa<UndefValue>(RHS) && ICmpInst::isEquality(Pred))
3048  return UndefValue::get(ITy);
3049 
3050  // icmp X, X -> true/false
3051  // icmp X, undef -> true/false because undef could be X.
3052  if (LHS == RHS || isa<UndefValue>(RHS))
3053  return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
3054 
3055  if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
3056  return V;
3057 
3058  if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
3059  return V;
3060 
3061  if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ))
3062  return V;
3063 
3064  // If both operands have range metadata, use the metadata
3065  // to simplify the comparison.
3066  if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) {
3067  auto RHS_Instr = cast<Instruction>(RHS);
3068  auto LHS_Instr = cast<Instruction>(LHS);
3069 
3070  if (Q.IIQ.getMetadata(RHS_Instr, LLVMContext::MD_range) &&
3071  Q.IIQ.getMetadata(LHS_Instr, LLVMContext::MD_range)) {
3072  auto RHS_CR = getConstantRangeFromMetadata(
3073  *RHS_Instr->getMetadata(LLVMContext::MD_range));
3074  auto LHS_CR = getConstantRangeFromMetadata(
3075  *LHS_Instr->getMetadata(LLVMContext::MD_range));
3076 
3077  auto Satisfied_CR = ConstantRange::makeSatisfyingICmpRegion(Pred, RHS_CR);
3078  if (Satisfied_CR.contains(LHS_CR))
3079  return ConstantInt::getTrue(RHS->getContext());
3080 
3081  auto InversedSatisfied_CR = ConstantRange::makeSatisfyingICmpRegion(
3082  CmpInst::getInversePredicate(Pred), RHS_CR);
3083  if (InversedSatisfied_CR.contains(LHS_CR))
3084  return ConstantInt::getFalse(RHS->getContext());
3085  }
3086  }
3087 
3088  // Compare of cast, for example (zext X) != 0 -> X != 0
3089  if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
3090  Instruction *LI = cast<CastInst>(LHS);
3091  Value *SrcOp = LI->getOperand(0);
3092  Type *SrcTy = SrcOp->getType();
3093  Type *DstTy = LI->getType();
3094 
3095  // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
3096  // if the integer type is the same size as the pointer type.
3097  if (MaxRecurse && isa<PtrToIntInst>(LI) &&
3098  Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
3099  if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
3100  // Transfer the cast to the constant.
3101  if (Value *V = SimplifyICmpInst(Pred, SrcOp,
3102  ConstantExpr::getIntToPtr(RHSC, SrcTy),
3103  Q, MaxRecurse-1))
3104  return V;
3105  } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
3106  if (RI->getOperand(0)->getType() == SrcTy)
3107  // Compare without the cast.
3108  if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
3109  Q, MaxRecurse-1))
3110  return V;
3111  }
3112  }
3113 
3114  if (isa<ZExtInst>(LHS)) {
3115  // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
3116  // same type.
3117  if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
3118  if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3119  // Compare X and Y. Note that signed predicates become unsigned.
3121  SrcOp, RI->getOperand(0), Q,
3122  MaxRecurse-1))
3123  return V;
3124  }
3125  // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
3126  // too. If not, then try to deduce the result of the comparison.
3127  else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
3128  // Compute the constant that would happen if we truncated to SrcTy then
3129  // reextended to DstTy.
3130  Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
3131  Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
3132 
3133  // If the re-extended constant didn't change then this is effectively
3134  // also a case of comparing two zero-extended values.
3135  if (RExt == CI && MaxRecurse)
3137  SrcOp, Trunc, Q, MaxRecurse-1))
3138  return V;
3139 
3140  // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
3141  // there. Use this to work out the result of the comparison.
3142  if (RExt != CI) {
3143  switch (Pred) {
3144  default: llvm_unreachable("Unknown ICmp predicate!");
3145  // LHS <u RHS.
3146  case ICmpInst::ICMP_EQ:
3147  case ICmpInst::ICMP_UGT:
3148  case ICmpInst::ICMP_UGE:
3149  return ConstantInt::getFalse(CI->getContext());
3150 
3151  case ICmpInst::ICMP_NE:
3152  case ICmpInst::ICMP_ULT:
3153  case ICmpInst::ICMP_ULE:
3154  return ConstantInt::getTrue(CI->getContext());
3155 
3156  // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
3157  // is non-negative then LHS <s RHS.
3158  case ICmpInst::ICMP_SGT:
3159  case ICmpInst::ICMP_SGE:
3160  return CI->getValue().isNegative() ?
3161  ConstantInt::getTrue(CI->getContext()) :
3162  ConstantInt::getFalse(CI->getContext());
3163 
3164  case ICmpInst::ICMP_SLT:
3165  case ICmpInst::ICMP_SLE:
3166  return CI->getValue().isNegative() ?
3167  ConstantInt::getFalse(CI->getContext()) :
3168  ConstantInt::getTrue(CI->getContext());
3169  }
3170  }
3171  }
3172  }
3173 
3174  if (isa<SExtInst>(LHS)) {
3175  // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
3176  // same type.
3177  if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
3178  if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3179  // Compare X and Y. Note that the predicate does not change.
3180  if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
3181  Q, MaxRecurse-1))
3182  return V;
3183  }
3184  // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
3185  // too. If not, then try to deduce the result of the comparison.
3186  else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
3187  // Compute the constant that would happen if we truncated to SrcTy then
3188  // reextended to DstTy.
3189  Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
3190  Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
3191 
3192  // If the re-extended constant didn't change then this is effectively
3193  // also a case of comparing two sign-extended values.
3194  if (RExt == CI && MaxRecurse)
3195  if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
3196  return V;
3197 
3198  // Otherwise the upper bits of LHS are all equal, while RHS has varying
3199  // bits there. Use this to work out the result of the comparison.
3200  if (RExt != CI) {
3201  switch (Pred) {
3202  default: llvm_unreachable("Unknown ICmp predicate!");
3203  case ICmpInst::ICMP_EQ:
3204  return ConstantInt::getFalse(CI->getContext());
3205  case ICmpInst::ICMP_NE:
3206  return ConstantInt::getTrue(CI->getContext());
3207 
3208  // If RHS is non-negative then LHS <s RHS. If RHS is negative then
3209  // LHS >s RHS.
3210  case ICmpInst::ICMP_SGT:
3211  case ICmpInst::ICMP_SGE:
3212  return CI->getValue().isNegative() ?
3213  ConstantInt::getTrue(CI->getContext()) :
3214  ConstantInt::getFalse(CI->getContext());
3215  case ICmpInst::ICMP_SLT:
3216  case ICmpInst::ICMP_SLE:
3217  return CI->getValue().isNegative() ?
3218  ConstantInt::getFalse(CI->getContext()) :
3219  ConstantInt::getTrue(CI->getContext());
3220 
3221  // If LHS is non-negative then LHS <u RHS. If LHS is negative then
3222  // LHS >u RHS.
3223  case ICmpInst::ICMP_UGT:
3224  case ICmpInst::ICMP_UGE:
3225  // Comparison is true iff the LHS <s 0.
3226  if (MaxRecurse)
3227  if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
3228  Constant::getNullValue(SrcTy),
3229  Q, MaxRecurse-1))
3230  return V;
3231  break;
3232  case ICmpInst::ICMP_ULT:
3233  case ICmpInst::ICMP_ULE:
3234  // Comparison is true iff the LHS >=s 0.
3235  if (MaxRecurse)
3236  if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
3237  Constant::getNullValue(SrcTy),
3238  Q, MaxRecurse-1))
3239  return V;
3240  break;
3241  }
3242  }
3243  }
3244  }
3245  }
3246 
3247  // icmp eq|ne X, Y -> false|true if X != Y
3248  if (ICmpInst::isEquality(Pred) &&
3249  isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) {
3250  return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy);
3251  }
3252 
3253  if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse))
3254  return V;
3255 
3256  if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse))
3257  return V;
3258 
3259  // Simplify comparisons of related pointers using a powerful, recursive
3260  // GEP-walk when we have target data available..
3261  if (LHS->getType()->isPointerTy())
3262  if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.AC, Q.CxtI,
3263  Q.IIQ, LHS, RHS))
3264  return C;
3265  if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS))
3266  if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS))
3267  if (Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) ==
3268  Q.DL.getTypeSizeInBits(CLHS->getType()) &&
3269  Q.DL.getTypeSizeInBits(CRHS->getPointerOperandType()) ==
3270  Q.DL.getTypeSizeInBits(CRHS->getType()))
3271  if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.AC, Q.CxtI,
3272  Q.IIQ, CLHS->getPointerOperand(),
3273  CRHS->getPointerOperand()))
3274  return C;
3275 
3276  if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
3277  if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
3278  if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
3279  GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
3280  (ICmpInst::isEquality(Pred) ||
3281  (GLHS->isInBounds() && GRHS->isInBounds() &&
3282  Pred == ICmpInst::getSignedPredicate(Pred)))) {
3283  // The bases are equal and the indices are constant. Build a constant
3284  // expression GEP with the same indices and a null base pointer to see
3285  // what constant folding can make out of it.
3286  Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
3287  SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
3289  GLHS->getSourceElementType(), Null, IndicesLHS);
3290 
3291  SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
3293  GLHS->getSourceElementType(), Null, IndicesRHS);
3294  return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
3295  }
3296  }
3297  }
3298 
3299  // If the comparison is with the result of a select instruction, check whether
3300  // comparing with either branch of the select always yields the same value.
3301  if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3302  if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3303  return V;
3304 
3305  // If the comparison is with the result of a phi instruction, check whether
3306  // doing the compare with each incoming phi value yields a common result.
3307  if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3308  if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3309  return V;
3310 
3311  return nullptr;
3312 }
3313 
3314 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3315  const SimplifyQuery &Q) {
3316  return ::SimplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
3317 }
3318 
3319 /// Given operands for an FCmpInst, see if we can fold the result.
3320 /// If not, this returns null.
3321 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3322  FastMathFlags FMF, const SimplifyQuery &Q,
3323  unsigned MaxRecurse) {
3324  CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3325  assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
3326 
3327  if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3328  if (Constant *CRHS = dyn_cast<Constant>(RHS))
3329  return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3330 
3331  // If we have a constant, make sure it is on the RHS.
3332  std::swap(LHS, RHS);
3333  Pred = CmpInst::getSwappedPredicate(Pred);
3334  }
3335 
3336  // Fold trivial predicates.
3337  Type *RetTy = GetCompareTy(LHS);
3338  if (Pred == FCmpInst::FCMP_FALSE)
3339  return getFalse(RetTy);
3340  if (Pred == FCmpInst::FCMP_TRUE)
3341  return getTrue(RetTy);
3342 
3343  // Fold (un)ordered comparison if we can determine there are no NaNs.
3344  if (Pred == FCmpInst::FCMP_UNO || Pred == FCmpInst::FCMP_ORD)
3345  if (FMF.noNaNs() ||
3346  (isKnownNeverNaN(LHS, Q.TLI) && isKnownNeverNaN(RHS, Q.TLI)))
3347  return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD);
3348 
3349  // NaN is unordered; NaN is not ordered.
3351  "Comparison must be either ordered or unordered");
3352  if (match(RHS, m_NaN()))
3353  return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
3354 
3355  // fcmp pred x, undef and fcmp pred undef, x
3356  // fold to true if unordered, false if ordered
3357  if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS)) {
3358  // Choosing NaN for the undef will always make unordered comparison succeed
3359  // and ordered comparison fail.
3360  return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
3361  }
3362 
3363  // fcmp x,x -> true/false. Not all compares are foldable.
3364  if (LHS == RHS) {
3365  if (CmpInst::isTrueWhenEqual(Pred))
3366  return getTrue(RetTy);
3367  if (CmpInst::isFalseWhenEqual(Pred))
3368  return getFalse(RetTy);
3369  }
3370 
3371  // Handle fcmp with constant RHS.
3372  // TODO: Use match with a specific FP value, so these work with vectors with
3373  // undef lanes.
3374  const APFloat *C;
3375  if (match(RHS, m_APFloat(C))) {
3376  // Check whether the constant is an infinity.
3377  if (C->isInfinity()) {
3378  if (C->isNegative()) {
3379  switch (Pred) {
3380  case FCmpInst::FCMP_OLT:
3381  // No value is ordered and less than negative infinity.
3382  return getFalse(RetTy);
3383  case FCmpInst::FCMP_UGE:
3384  // All values are unordered with or at least negative infinity.
3385  return getTrue(RetTy);
3386  default:
3387  break;
3388  }
3389  } else {
3390  switch (Pred) {
3391  case FCmpInst::FCMP_OGT:
3392  // No value is ordered and greater than infinity.
3393  return getFalse(RetTy);
3394  case FCmpInst::FCMP_ULE:
3395  // All values are unordered with and at most infinity.
3396  return getTrue(RetTy);
3397  default:
3398  break;
3399  }
3400  }
3401  }
3402  if (C->isNegative() && !C->isNegZero()) {
3403  assert(!C->isNaN() && "Unexpected NaN constant!");
3404  // TODO: We can catch more cases by using a range check rather than
3405  // relying on CannotBeOrderedLessThanZero.
3406  switch (Pred) {
3407  case FCmpInst::FCMP_UGE:
3408  case FCmpInst::FCMP_UGT:
3409  case FCmpInst::FCMP_UNE:
3410  // (X >= 0) implies (X > C) when (C < 0)
3411  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3412  return getTrue(RetTy);
3413  break;
3414  case FCmpInst::FCMP_OEQ:
3415  case FCmpInst::FCMP_OLE:
3416  case FCmpInst::FCMP_OLT:
3417  // (X >= 0) implies !(X < C) when (C < 0)
3418  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3419  return getFalse(RetTy);
3420  break;
3421  default:
3422  break;
3423  }
3424  }
3425 
3426  // Check comparison of [minnum/maxnum with constant] with other constant.
3427  const APFloat *C2;
3428  if ((match(LHS, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_APFloat(C2))) &&
3429  C2->compare(*C) == APFloat::cmpLessThan) ||
3430  (match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) &&
3431  C2->compare(*C) == APFloat::cmpGreaterThan)) {
3432  bool IsMaxNum =
3433  cast<IntrinsicInst>(LHS)->getIntrinsicID() == Intrinsic::maxnum;
3434  // The ordered relationship and minnum/maxnum guarantee that we do not
3435  // have NaN constants, so ordered/unordered preds are handled the same.
3436  switch (Pred) {
3438  // minnum(X, LesserC) == C --> false
3439  // maxnum(X, GreaterC) == C --> false
3440  return getFalse(RetTy);
3442  // minnum(X, LesserC) != C --> true
3443  // maxnum(X, GreaterC) != C --> true
3444  return getTrue(RetTy);
3447  // minnum(X, LesserC) >= C --> false
3448  // minnum(X, LesserC) > C --> false
3449  // maxnum(X, GreaterC) >= C --> true
3450  // maxnum(X, GreaterC) > C --> true
3451  return ConstantInt::get(RetTy, IsMaxNum);
3454  // minnum(X, LesserC) <= C --> true
3455  // minnum(X, LesserC) < C --> true
3456  // maxnum(X, GreaterC) <= C --> false
3457  // maxnum(X, GreaterC) < C --> false
3458  return ConstantInt::get(RetTy, !IsMaxNum);
3459  default:
3460  // TRUE/FALSE/ORD/UNO should be handled before this.
3461  llvm_unreachable("Unexpected fcmp predicate");
3462  }
3463  }
3464  }
3465 
3466  if (match(RHS, m_AnyZeroFP())) {
3467  switch (Pred) {
3468  case FCmpInst::FCMP_OGE:
3469  case FCmpInst::FCMP_ULT:
3470  // Positive or zero X >= 0.0 --> true
3471  // Positive or zero X < 0.0 --> false
3472  if ((FMF.noNaNs() || isKnownNeverNaN(LHS, Q.TLI)) &&
3474  return Pred == FCmpInst::FCMP_OGE ? getTrue(RetTy) : getFalse(RetTy);
3475  break;
3476  case FCmpInst::FCMP_UGE:
3477  case FCmpInst::FCMP_OLT:
3478  // Positive or zero or nan X >= 0.0 --> true
3479  // Positive or zero or nan X < 0.0 --> false
3480  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3481  return Pred == FCmpInst::FCMP_UGE ? getTrue(RetTy) : getFalse(RetTy);
3482  break;
3483  default:
3484  break;
3485  }
3486  }
3487 
3488  // If the comparison is with the result of a select instruction, check whether
3489  // comparing with either branch of the select always yields the same value.
3490  if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3491  if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3492  return V;
3493 
3494  // If the comparison is with the result of a phi instruction, check whether
3495  // doing the compare with each incoming phi value yields a common result.
3496  if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3497  if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3498  return V;
3499 
3500  return nullptr;
3501 }
3502 
3503 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3504  FastMathFlags FMF, const SimplifyQuery &Q) {
3505  return ::SimplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit);
3506 }
3507 
3508 /// See if V simplifies when its operand Op is replaced with RepOp.
3509 static const Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
3510  const SimplifyQuery &Q,
3511  unsigned MaxRecurse) {
3512  // Trivial replacement.
3513  if (V == Op)
3514  return RepOp;
3515 
3516  // We cannot replace a constant, and shouldn't even try.
3517  if (isa<Constant>(Op))
3518  return nullptr;
3519 
3520  auto *I = dyn_cast<Instruction>(V);
3521  if (!I)
3522  return nullptr;
3523 
3524  // If this is a binary operator, try to simplify it with the replaced op.
3525  if (auto *B = dyn_cast<BinaryOperator>(I)) {
3526  // Consider:
3527  // %cmp = icmp eq i32 %x, 2147483647
3528  // %add = add nsw i32 %x, 1
3529  // %sel = select i1 %cmp, i32 -2147483648, i32 %add
3530  //
3531  // We can't replace %sel with %add unless we strip away the flags.
3532  if (isa<OverflowingBinaryOperator>(B))
3533  if (Q.IIQ.hasNoSignedWrap(B) || Q.IIQ.hasNoUnsignedWrap(B))
3534  return nullptr;
3535  if (isa<PossiblyExactOperator>(B) && Q.IIQ.isExact(B))
3536  return nullptr;
3537 
3538  if (MaxRecurse) {
3539  if (B->getOperand(0) == Op)
3540  return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), Q,
3541  MaxRecurse - 1);
3542  if (B->getOperand(1) == Op)
3543  return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, Q,
3544  MaxRecurse - 1);
3545  }
3546  }
3547 
3548  // Same for CmpInsts.
3549  if (CmpInst *C = dyn_cast<CmpInst>(I)) {
3550  if (MaxRecurse) {
3551  if (C->getOperand(0) == Op)
3552  return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), Q,
3553  MaxRecurse - 1);
3554  if (C->getOperand(1) == Op)
3555  return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, Q,
3556  MaxRecurse - 1);
3557  }
3558  }
3559 
3560  // Same for GEPs.
3561  if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
3562  if (MaxRecurse) {
3563  SmallVector<Value *, 8> NewOps(GEP->getNumOperands());
3564  transform(GEP->operands(), NewOps.begin(),
3565  [&](Value *V) { return V == Op ? RepOp : V; });
3566  return SimplifyGEPInst(GEP->getSourceElementType(), NewOps, Q,
3567  MaxRecurse - 1);
3568  }
3569  }
3570 
3571  // TODO: We could hand off more cases to instsimplify here.
3572 
3573  // If all operands are constant after substituting Op for RepOp then we can
3574  // constant fold the instruction.
3575  if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) {
3576  // Build a list of all constant operands.
3577  SmallVector<Constant *, 8> ConstOps;
3578  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
3579  if (I->getOperand(i) == Op)
3580  ConstOps.push_back(CRepOp);
3581  else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i)))
3582  ConstOps.push_back(COp);
3583  else
3584  break;
3585  }
3586 
3587  // All operands were constants, fold it.
3588  if (ConstOps.size() == I->getNumOperands()) {
3589  if (CmpInst *C = dyn_cast<CmpInst>(I))
3590  return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0],
3591  ConstOps[1], Q.DL, Q.TLI);
3592 
3593  if (LoadInst *LI = dyn_cast<LoadInst>(I))
3594  if (!LI->isVolatile())
3595  return ConstantFoldLoadFromConstPtr(ConstOps[0], LI->getType(), Q.DL);
3596 
3597  return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI);
3598  }
3599  }
3600 
3601  return nullptr;
3602 }
3603 
3604 /// Try to simplify a select instruction when its condition operand is an
3605 /// integer comparison where one operand of the compare is a constant.
3606 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X,
3607  const APInt *Y, bool TrueWhenUnset) {
3608  const APInt *C;
3609 
3610  // (X & Y) == 0 ? X & ~Y : X --> X
3611  // (X & Y) != 0 ? X & ~Y : X --> X & ~Y
3612  if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) &&
3613  *Y == ~*C)
3614  return TrueWhenUnset ? FalseVal : TrueVal;
3615 
3616  // (X & Y) == 0 ? X : X & ~Y --> X & ~Y
3617  // (X & Y) != 0 ? X : X & ~Y --> X
3618  if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) &&
3619  *Y == ~*C)
3620  return TrueWhenUnset ? FalseVal : TrueVal;
3621 
3622  if (Y->isPowerOf2()) {
3623  // (X & Y) == 0 ? X | Y : X --> X | Y
3624  // (X & Y) != 0 ? X | Y : X --> X
3625  if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) &&
3626  *Y == *C)
3627  return TrueWhenUnset ? TrueVal : FalseVal;
3628 
3629  // (X & Y) == 0 ? X : X | Y --> X
3630  // (X & Y) != 0 ? X : X | Y --> X | Y
3631  if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) &&
3632  *Y == *C)
3633  return TrueWhenUnset ? TrueVal : FalseVal;
3634  }
3635 
3636  return nullptr;
3637 }
3638 
3639 /// An alternative way to test if a bit is set or not uses sgt/slt instead of
3640 /// eq/ne.
3642  ICmpInst::Predicate Pred,
3643  Value *TrueVal, Value *FalseVal) {
3644  Value *X;
3645  APInt Mask;
3646  if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask))
3647  return nullptr;
3648 
3649  return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask,
3650  Pred == ICmpInst::ICMP_EQ);
3651 }
3652 
3653 /// Try to simplify a select instruction when its condition operand is an
3654 /// integer comparison.
3655 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
3656  Value *FalseVal, const SimplifyQuery &Q,
3657  unsigned MaxRecurse) {
3658  ICmpInst::Predicate Pred;
3659  Value *CmpLHS, *CmpRHS;
3660  if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
3661  return nullptr;
3662 
3663  if (ICmpInst::isEquality(Pred) && match(CmpRHS, m_Zero())) {
3664  Value *X;
3665  const APInt *Y;
3666  if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y))))
3667  if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y,
3668  Pred == ICmpInst::ICMP_EQ))
3669  return V;
3670 
3671  // Test for a bogus zero-shift-guard-op around funnel-shift or rotate.
3672  Value *ShAmt;
3673  auto isFsh = m_CombineOr(m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(),
3674  m_Value(ShAmt)),
3675  m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X),
3676  m_Value(ShAmt)));
3677  // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X
3678  // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X
3679  if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt &&
3680  Pred == ICmpInst::ICMP_EQ)
3681  return X;
3682  // (ShAmt != 0) ? X : fshl(X, *, ShAmt) --> X
3683  // (ShAmt != 0) ? X : fshr(*, X, ShAmt) --> X
3684  if (match(FalseVal, isFsh) && TrueVal == X && CmpLHS == ShAmt &&
3685  Pred == ICmpInst::ICMP_NE)
3686  return X;
3687 
3688  // Test for a zero-shift-guard-op around rotates. These are used to
3689  // avoid UB from oversized shifts in raw IR rotate patterns, but the
3690  // intrinsics do not have that problem.
3691  // We do not allow this transform for the general funnel shift case because
3692  // that would not preserve the poison safety of the original code.
3693  auto isRotate = m_CombineOr(m_Intrinsic<Intrinsic::fshl>(m_Value(X),
3694  m_Deferred(X),
3695  m_Value(ShAmt)),
3696  m_Intrinsic<Intrinsic::fshr>(m_Value(X),
3697  m_Deferred(X),
3698  m_Value(ShAmt)));
3699  // (ShAmt != 0) ? fshl(X, X, ShAmt) : X --> fshl(X, X, ShAmt)
3700  // (ShAmt != 0) ? fshr(X, X, ShAmt) : X --> fshr(X, X, ShAmt)
3701  if (match(TrueVal, isRotate) && FalseVal == X && CmpLHS == ShAmt &&
3702  Pred == ICmpInst::ICMP_NE)
3703  return TrueVal;
3704  // (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt)
3705  // (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt)
3706  if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt &&
3707  Pred == ICmpInst::ICMP_EQ)
3708  return FalseVal;
3709  }
3710 
3711  // Check for other compares that behave like bit test.
3712  if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred,
3713  TrueVal, FalseVal))
3714  return V;
3715 
3716  // If we have an equality comparison, then we know the value in one of the
3717  // arms of the select. See if substituting this value into the arm and
3718  // simplifying the result yields the same value as the other arm.
3719  if (Pred == ICmpInst::ICMP_EQ) {
3720  if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3721  TrueVal ||
3722  SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3723  TrueVal)
3724  return FalseVal;
3725  if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3726  FalseVal ||
3727  SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3728  FalseVal)
3729  return FalseVal;
3730  } else if (Pred == ICmpInst::ICMP_NE) {
3731  if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3732  FalseVal ||
3733  SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3734  FalseVal)
3735  return TrueVal;
3736  if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3737  TrueVal ||
3738  SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3739  TrueVal)
3740  return TrueVal;
3741  }
3742 
3743  return nullptr;
3744 }
3745 
3746 /// Try to simplify a select instruction when its condition operand is a
3747 /// floating-point comparison.
3749  FCmpInst::Predicate Pred;
3750  if (!match(Cond, m_FCmp(Pred, m_Specific(T), m_Specific(F))) &&
3751  !match(Cond, m_FCmp(Pred, m_Specific(F), m_Specific(T))))
3752  return nullptr;
3753 
3754  // TODO: The transform may not be valid with -0.0. An incomplete way of
3755  // testing for that possibility is to check if at least one operand is a
3756  // non-zero constant.
3757  const APFloat *C;
3758  if ((match(T, m_APFloat(C)) && C->isNonZero()) ||
3759  (match(F, m_APFloat(C)) && C->isNonZero())) {
3760  // (T == F) ? T : F --> F
3761  // (F == T) ? T : F --> F
3762  if (Pred == FCmpInst::FCMP_OEQ)
3763  return F;
3764 
3765  // (T != F) ? T : F --> T
3766  // (F != T) ? T : F --> T
3767  if (Pred == FCmpInst::FCMP_UNE)
3768  return T;
3769  }
3770 
3771  return nullptr;
3772 }
3773 
3774 /// Given operands for a SelectInst, see if we can fold the result.
3775 /// If not, this returns null.
3776 static Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3777  const SimplifyQuery &Q, unsigned MaxRecurse) {
3778  if (auto *CondC = dyn_cast<Constant>(Cond)) {
3779  if (auto *TrueC = dyn_cast<Constant>(TrueVal))
3780  if (auto *FalseC = dyn_cast<Constant>(FalseVal))
3781  return ConstantFoldSelectInstruction(CondC, TrueC, FalseC);
3782 
3783  // select undef, X, Y -> X or Y
3784  if (isa<UndefValue>(CondC))
3785  return isa<Constant>(FalseVal) ? FalseVal : TrueVal;
3786 
3787  // TODO: Vector constants with undef elements don't simplify.
3788 
3789  // select true, X, Y -> X
3790  if (CondC->isAllOnesValue())
3791  return TrueVal;
3792  // select false, X, Y -> Y
3793  if (CondC->isNullValue())
3794  return FalseVal;
3795  }
3796 
3797  // select ?, X, X -> X
3798  if (TrueVal == FalseVal)
3799  return TrueVal;
3800 
3801  if (isa<UndefValue>(TrueVal)) // select ?, undef, X -> X
3802  return FalseVal;
3803  if (isa<UndefValue>(FalseVal)) // select ?, X, undef -> X
3804  return TrueVal;
3805 
3806  if (Value *V =
3807  simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse))
3808  return V;
3809 
3810  if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal))
3811  return V;
3812 
3813  if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal))
3814  return V;
3815 
3816  Optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL);
3817  if (Imp)
3818  return *Imp ? TrueVal : FalseVal;
3819 
3820  return nullptr;
3821 }
3822 
3823 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3824  const SimplifyQuery &Q) {
3825  return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit);
3826 }
3827 
3828 /// Given operands for an GetElementPtrInst, see if we can fold the result.
3829 /// If not, this returns null.
3831  const SimplifyQuery &Q, unsigned) {
3832  // The type of the GEP pointer operand.
3833  unsigned AS =
3834  cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace();
3835 
3836  // getelementptr P -> P.
3837  if (Ops.size() == 1)
3838  return Ops[0];
3839 
3840  // Compute the (pointer) type returned by the GEP instruction.
3841  Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1));
3842  Type *GEPTy = PointerType::get(LastType, AS);
3843  if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
3844  GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3845  else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType()))
3846  GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3847 
3848  if (isa<UndefValue>(Ops[0]))
3849  return UndefValue::get(GEPTy);
3850 
3851  if (Ops.size() == 2) {
3852  // getelementptr P, 0 -> P.
3853  if (match(Ops[1], m_Zero()) && Ops[0]->getType() == GEPTy)
3854  return Ops[0];
3855 
3856  Type *Ty = SrcTy;
3857  if (Ty->isSized()) {
3858  Value *P;
3859  uint64_t C;
3860  uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty);
3861  // getelementptr P, N -> P if P points to a type of zero size.
3862  if (TyAllocSize == 0 && Ops[0]->getType() == GEPTy)
3863  return Ops[0];
3864 
3865  // The following transforms are only safe if the ptrtoint cast
3866  // doesn't truncate the pointers.
3867  if (Ops[1]->getType()->getScalarSizeInBits() ==
3868  Q.DL.getIndexSizeInBits(AS)) {
3869  auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * {
3870  if (match(P, m_Zero()))
3871  return Constant::getNullValue(GEPTy);
3872  Value *Temp;
3873  if (match(P, m_PtrToInt(m_Value(Temp))))
3874  if (Temp->getType() == GEPTy)
3875  return Temp;
3876  return nullptr;
3877  };
3878 
3879  // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
3880  if (TyAllocSize == 1 &&
3881  match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0])))))
3882  if (Value *R = PtrToIntOrZero(P))
3883  return R;
3884 
3885  // getelementptr V, (ashr (sub P, V), C) -> Q
3886  // if P points to a type of size 1 << C.
3887  if (match(Ops[1],
3888  m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3889  m_ConstantInt(C))) &&
3890  TyAllocSize == 1ULL << C)
3891  if (Value *R = PtrToIntOrZero(P))
3892  return R;
3893 
3894  // getelementptr V, (sdiv (sub P, V), C) -> Q
3895  // if P points to a type of size C.
3896  if (match(Ops[1],
3897  m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3898  m_SpecificInt(TyAllocSize))))
3899  if (Value *R = PtrToIntOrZero(P))
3900  return R;
3901  }
3902  }
3903  }
3904 
3905  if (Q.DL.getTypeAllocSize(LastType) == 1 &&
3906  all_of(Ops.slice(1).drop_back(1),
3907  [](Value *Idx) { return match(Idx, m_Zero()); })) {
3908  unsigned IdxWidth =
3909  Q.DL.getIndexSizeInBits(Ops[0]->getType()->getPointerAddressSpace());
3910  if (Q.DL.getTypeSizeInBits(Ops.back()->getType()) == IdxWidth) {
3911  APInt BasePtrOffset(IdxWidth, 0);
3912  Value *StrippedBasePtr =
3913  Ops[0]->stripAndAccumulateInBoundsConstantOffsets(Q.DL,
3914  BasePtrOffset);
3915 
3916  // gep (gep V, C), (sub 0, V) -> C
3917  if (match(Ops.back(),
3918  m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr))))) {
3919  auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset);
3920  return ConstantExpr::getIntToPtr(CI, GEPTy);
3921  }
3922  // gep (gep V, C), (xor V, -1) -> C-1
3923  if (match(Ops.back(),
3924  m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes()))) {
3925  auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1);
3926  return ConstantExpr::getIntToPtr(CI, GEPTy);
3927  }
3928  }
3929  }
3930 
3931  // Check to see if this is constant foldable.
3932  if (!all_of(Ops, [](Value *V) { return isa<Constant>(V); }))
3933  return nullptr;
3934 
3935  auto *CE = ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]),
3936  Ops.slice(1));
3937  if (auto *CEFolded = ConstantFoldConstant(CE, Q.DL))
3938  return CEFolded;
3939  return CE;
3940 }
3941 
3943  const SimplifyQuery &Q) {
3944  return ::SimplifyGEPInst(SrcTy, Ops, Q, RecursionLimit);
3945 }
3946 
3947 /// Given operands for an InsertValueInst, see if we can fold the result.
3948 /// If not, this returns null.
3950  ArrayRef<unsigned> Idxs, const SimplifyQuery &Q,
3951  unsigned) {
3952  if (Constant *CAgg = dyn_cast<Constant>(Agg))
3953  if (Constant *CVal = dyn_cast<Constant>(Val))
3954  return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
3955 
3956  // insertvalue x, undef, n -> x
3957  if (match(Val, m_Undef()))
3958  return Agg;
3959 
3960  // insertvalue x, (extractvalue y, n), n
3961  if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
3962  if (EV->getAggregateOperand()->getType() == Agg->getType() &&
3963  EV->getIndices() == Idxs) {
3964  // insertvalue undef, (extractvalue y, n), n -> y
3965  if (match(Agg, m_Undef()))
3966  return EV->getAggregateOperand();
3967 
3968  // insertvalue y, (extractvalue y, n), n -> y
3969  if (Agg == EV->getAggregateOperand())
3970  return Agg;
3971  }
3972 
3973  return nullptr;
3974 }
3975 
3977  ArrayRef<unsigned> Idxs,
3978  const SimplifyQuery &Q) {
3980 }
3981 
3983  const SimplifyQuery &Q) {
3984  // Try to constant fold.
3985  auto *VecC = dyn_cast<Constant>(Vec);
3986  auto *ValC = dyn_cast<Constant>(Val);
3987  auto *IdxC = dyn_cast<Constant>(Idx);
3988  if (VecC && ValC && IdxC)
3989  return ConstantFoldInsertElementInstruction(VecC, ValC, IdxC);
3990 
3991  // Fold into undef if index is out of bounds.
3992  if (auto *CI = dyn_cast<ConstantInt>(Idx)) {
3993  uint64_t NumElements = cast<VectorType>(Vec->getType())->getNumElements();
3994  if (CI->uge(NumElements))
3995  return UndefValue::get(Vec->getType());
3996  }
3997 
3998  // If index is undef, it might be out of bounds (see above case)
3999  if (isa<UndefValue>(Idx))
4000  return UndefValue::get(Vec->getType());
4001 
4002  // Inserting an undef scalar? Assume it is the same value as the existing
4003  // vector element.
4004  if (isa<UndefValue>(Val))
4005  return Vec;
4006 
4007  // If we are extracting a value from a vector, then inserting it into the same
4008  // place, that's the input vector:
4009  // insertelt Vec, (extractelt Vec, Idx), Idx --> Vec
4010  if (match(Val, m_ExtractElement(m_Specific(Vec), m_Specific(Idx))))
4011  return Vec;
4012 
4013  return nullptr;
4014 }
4015 
4016 /// Given operands for an ExtractValueInst, see if we can fold the result.
4017 /// If not, this returns null.
4019  const SimplifyQuery &, unsigned) {
4020  if (auto *CAgg = dyn_cast<Constant>(Agg))
4021  return ConstantFoldExtractValueInstruction(CAgg, Idxs);
4022 
4023  // extractvalue x, (insertvalue y, elt, n), n -> elt
4024  unsigned NumIdxs = Idxs.size();
4025  for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr;
4026  IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) {
4027  ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices();
4028  unsigned NumInsertValueIdxs = InsertValueIdxs.size();
4029  unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs);
4030  if (InsertValueIdxs.slice(0, NumCommonIdxs) ==
4031  Idxs.slice(0, NumCommonIdxs)) {
4032  if (NumIdxs == NumInsertValueIdxs)
4033  return IVI->getInsertedValueOperand();
4034  break;
4035  }
4036  }
4037 
4038  return nullptr;
4039 }
4040 
4042  const SimplifyQuery &Q) {
4044 }
4045 
4046 /// Given operands for an ExtractElementInst, see if we can fold the result.
4047 /// If not, this returns null.
4049  unsigned) {
4050  if (auto *CVec = dyn_cast<Constant>(Vec)) {
4051  if (auto *CIdx = dyn_cast<Constant>(Idx))
4052  return ConstantFoldExtractElementInstruction(CVec, CIdx);
4053 
4054  // The index is not relevant if our vector is a splat.
4055  if (auto *Splat = CVec->getSplatValue())
4056  return Splat;
4057 
4058  if (isa<UndefValue>(Vec))
4059  return UndefValue::get(Vec->getType()->getVectorElementType());
4060  }
4061 
4062  // If extracting a specified index from the vector, see if we can recursively
4063  // find a previously computed scalar that was inserted into the vector.
4064  if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) {
4065  if (IdxC->getValue().uge(Vec->getType()->getVectorNumElements()))
4066  // definitely out of bounds, thus undefined result
4067  return UndefValue::get(Vec->getType()->getVectorElementType());
4068  if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
4069  return Elt;
4070  }
4071 
4072  // An undef extract index can be arbitrarily chosen to be an out-of-range
4073  // index value, which would result in the instruction being undef.
4074  if (isa<UndefValue>(Idx))
4075  return UndefValue::get(Vec->getType()->getVectorElementType());
4076 
4077  return nullptr;
4078 }
4079 
4081  const SimplifyQuery &Q) {
4083 }
4084 
4085 /// See if we can fold the given phi. If not, returns null.
4086 static Value *SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q) {
4087  // If all of the PHI's incoming values are the same then replace the PHI node
4088  // with the common value.
4089  Value *CommonValue = nullptr;
4090  bool HasUndefInput = false;
4091  for (Value *Incoming : PN->incoming_values()) {
4092  // If the incoming value is the phi node itself, it can safely be skipped.
4093  if (Incoming == PN) continue;
4094  if (isa<UndefValue>(Incoming)) {
4095  // Remember that we saw an undef value, but otherwise ignore them.
4096  HasUndefInput = true;
4097  continue;
4098  }
4099  if (CommonValue && Incoming != CommonValue)
4100  return nullptr; // Not the same, bail out.
4101  CommonValue = Incoming;
4102  }
4103 
4104  // If CommonValue is null then all of the incoming values were either undef or
4105  // equal to the phi node itself.
4106  if (!CommonValue)
4107  return UndefValue::get(PN->getType());
4108 
4109  // If we have a PHI node like phi(X, undef, X), where X is defined by some
4110  // instruction, we cannot return X as the result of the PHI node unless it
4111  // dominates the PHI block.
4112  if (HasUndefInput)
4113  return valueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr;
4114 
4115  return CommonValue;
4116 }
4117 
4118 static Value *SimplifyCastInst(unsigned CastOpc, Value *Op,
4119  Type *Ty, const SimplifyQuery &Q, unsigned MaxRecurse) {
4120  if (auto *C = dyn_cast<Constant>(Op))
4121  return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL);
4122 
4123  if (auto *CI = dyn_cast<CastInst>(Op)) {
4124  auto *Src = CI->getOperand(0);
4125  Type *SrcTy = Src->getType();
4126  Type *MidTy = CI->getType();
4127  Type *DstTy = Ty;
4128  if (Src->getType() == Ty) {
4129  auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode());
4130  auto SecondOp = static_cast<Instruction::CastOps>(CastOpc);
4131  Type *SrcIntPtrTy =
4132  SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr;
4133  Type *MidIntPtrTy =
4134  MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr;
4135  Type *DstIntPtrTy =
4136  DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr;
4137  if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy,
4138  SrcIntPtrTy, MidIntPtrTy,
4139  DstIntPtrTy) == Instruction::BitCast)
4140  return Src;
4141  }
4142  }
4143 
4144  // bitcast x -> x
4145  if (CastOpc == Instruction::BitCast)
4146  if (Op->getType() == Ty)
4147  return Op;
4148 
4149  return nullptr;
4150 }
4151 
4152 Value *llvm::SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
4153  const SimplifyQuery &Q) {
4154  return ::SimplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit);
4155 }
4156 
4157 /// For the given destination element of a shuffle, peek through shuffles to
4158 /// match a root vector source operand that contains that element in the same
4159 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s).
4160 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1,
4161  int MaskVal, Value *RootVec,
4162  unsigned MaxRecurse) {
4163  if (!MaxRecurse--)
4164  return nullptr;
4165 
4166  // Bail out if any mask value is undefined. That kind of shuffle may be
4167  // simplified further based on demanded bits or other folds.
4168  if (MaskVal == -1)
4169  return nullptr;
4170 
4171  // The mask value chooses which source operand we need to look at next.
4172  int InVecNumElts = Op0->getType()->getVectorNumElements();
4173  int RootElt = MaskVal;
4174  Value *SourceOp = Op0;
4175  if (MaskVal >= InVecNumElts) {
4176  RootElt = MaskVal - InVecNumElts;
4177  SourceOp = Op1;
4178  }
4179 
4180  // If the source operand is a shuffle itself, look through it to find the
4181  // matching root vector.
4182  if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) {
4183  return foldIdentityShuffles(
4184  DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1),
4185  SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse);
4186  }
4187 
4188  // TODO: Look through bitcasts? What if the bitcast changes the vector element
4189  // size?
4190 
4191  // The source operand is not a shuffle. Initialize the root vector value for
4192  // this shuffle if that has not been done yet.
4193  if (!RootVec)
4194  RootVec = SourceOp;
4195 
4196  // Give up as soon as a source operand does not match the existing root value.
4197  if (RootVec != SourceOp)
4198  return nullptr;
4199 
4200  // The element must be coming from the same lane in the source vector
4201  // (although it may have crossed lanes in intermediate shuffles).
4202  if (RootElt != DestElt)
4203  return nullptr;
4204 
4205  return RootVec;
4206 }
4207 
4209  Type *RetTy, const SimplifyQuery &Q,
4210  unsigned MaxRecurse) {
4211  if (isa<UndefValue>(Mask))
4212  return UndefValue::get(RetTy);
4213 
4214  Type *InVecTy = Op0->getType();
4215  unsigned MaskNumElts = Mask->getType()->getVectorNumElements();
4216  unsigned InVecNumElts = InVecTy->getVectorNumElements();
4217 
4218  SmallVector<int, 32> Indices;
4219  ShuffleVectorInst::getShuffleMask(Mask, Indices);
4220  assert(MaskNumElts == Indices.size() &&
4221  "Size of Indices not same as number of mask elements?");
4222 
4223  // Canonicalization: If mask does not select elements from an input vector,
4224  // replace that input vector with undef.
4225  bool MaskSelects0 = false, MaskSelects1 = false;
4226  for (unsigned i = 0; i != MaskNumElts; ++i) {
4227  if (Indices[i] == -1)
4228  continue;
4229  if ((unsigned)Indices[i] < InVecNumElts)
4230  MaskSelects0 = true;
4231  else
4232  MaskSelects1 = true;
4233  }
4234  if (!MaskSelects0)
4235  Op0 = UndefValue::get(InVecTy);
4236  if (!MaskSelects1)
4237  Op1 = UndefValue::get(InVecTy);
4238 
4239  auto *Op0Const = dyn_cast<Constant>(Op0);
4240  auto *Op1Const = dyn_cast<Constant>(Op1);
4241 
4242  // If all operands are constant, constant fold the shuffle.
4243  if (Op0Const && Op1Const)
4244  return ConstantFoldShuffleVectorInstruction(Op0Const, Op1Const, Mask);
4245 
4246  // Canonicalization: if only one input vector is constant, it shall be the
4247  // second one.
4248  if (Op0Const && !Op1Const) {
4249  std::swap(Op0, Op1);
4250  ShuffleVectorInst::commuteShuffleMask(Indices, InVecNumElts);
4251  }
4252 
4253  // A shuffle of a splat is always the splat itself. Legal if the shuffle's
4254  // value type is same as the input vectors' type.
4255  if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0))
4256  if (isa<UndefValue>(Op1) && RetTy == InVecTy &&
4257  OpShuf->getMask()->getSplatValue())
4258  return Op0;
4259 
4260  // Don't fold a shuffle with undef mask elements. This may get folded in a
4261  // better way using demanded bits or other analysis.
4262  // TODO: Should we allow this?
4263  if (find(Indices, -1) != Indices.end())
4264  return nullptr;
4265 
4266  // Check if every element of this shuffle can be mapped back to the
4267  // corresponding element of a single root vector. If so, we don't need this
4268  // shuffle. This handles simple identity shuffles as well as chains of
4269  // shuffles that may widen/narrow and/or move elements across lanes and back.
4270  Value *RootVec = nullptr;
4271  for (unsigned i = 0; i != MaskNumElts; ++i) {
4272  // Note that recursion is limited for each vector element, so if any element
4273  // exceeds the limit, this will fail to simplify.
4274  RootVec =
4275  foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse);
4276 
4277  // We can't replace a widening/narrowing shuffle with one of its operands.
4278  if (!RootVec || RootVec->getType() != RetTy)
4279  return nullptr;
4280  }
4281  return RootVec;
4282 }
4283 
4284 /// Given operands for a ShuffleVectorInst, fold the result or return null.
4286  Type *RetTy, const SimplifyQuery &Q) {
4287  return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit);
4288 }
4289 
4291  Value *&Op, const SimplifyQuery &Q) {
4292  if (auto *C = dyn_cast<Constant>(Op))
4293  return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL);
4294  return nullptr;
4295 }
4296 
4297 /// Given the operand for an FNeg, see if we can fold the result. If not, this
4298 /// returns null.
4300  const SimplifyQuery &Q, unsigned MaxRecurse) {
4301  if (Constant *C = foldConstant(Instruction::FNeg, Op, Q))
4302  return C;
4303 
4304  Value *X;
4305  // fneg (fneg X) ==> X
4306  if (match(Op, m_FNeg(m_Value(X))))
4307  return X;
4308 
4309  return nullptr;
4310 }
4311 
4313  const SimplifyQuery &Q) {
4315 }
4316 
4318  // If the input is a vector with undef elements, just return a default NaN.
4319  if (!In->isNaN())
4320  return ConstantFP::getNaN(In->getType());
4321 
4322  // Propagate the existing NaN constant when possible.
4323  // TODO: Should we quiet a signaling NaN?
4324  return In;
4325 }
4326 
4327 static Constant *simplifyFPBinop(Value *Op0, Value *Op1) {
4328  if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1))
4329  return ConstantFP::getNaN(Op0->getType());
4330 
4331  if (match(Op0, m_NaN()))
4332  return propagateNaN(cast<Constant>(Op0));
4333  if (match(Op1, m_NaN()))
4334  return propagateNaN(cast<Constant>(Op1));
4335 
4336  return nullptr;
4337 }
4338 
4339 /// Given operands for an FAdd, see if we can fold the result. If not, this
4340 /// returns null.
4342  const SimplifyQuery &Q, unsigned MaxRecurse) {
4343  if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q))
4344  return C;
4345 
4346  if (Constant *C = simplifyFPBinop(Op0, Op1))
4347  return C;
4348 
4349  // fadd X, -0 ==> X
4350  if (match(Op1, m_NegZeroFP()))
4351  return Op0;
4352 
4353  // fadd X, 0 ==> X, when we know X is not -0
4354  if (match(Op1, m_PosZeroFP()) &&
4355  (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
4356  return Op0;
4357 
4358  // With nnan: -X + X --> 0.0 (and commuted variant)
4359  // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN.
4360  // Negative zeros are allowed because we always end up with positive zero:
4361  // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0
4362  // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0
4363  // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0
4364  // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0
4365  if (FMF.noNaNs()) {
4366  if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) ||
4367  match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0))))
4368  return ConstantFP::getNullValue(Op0->getType());
4369 
4370  if (match(Op0, m_FNeg(m_Specific(Op1))) ||
4371  match(Op1, m_FNeg(m_Specific(Op0))))
4372  return ConstantFP::getNullValue(Op0->getType());
4373  }
4374 
4375  // (X - Y) + Y --> X
4376  // Y + (X - Y) --> X
4377  Value *X;
4378  if (FMF.noSignedZeros() && FMF.allowReassoc() &&
4379  (match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) ||
4380  match(Op1, m_FSub(m_Value(X), m_Specific(Op0)))))
4381  return X;
4382 
4383  return nullptr;
4384 }
4385 
4386 /// Given operands for an FSub, see if we can fold the result. If not, this
4387 /// returns null.
4389  const SimplifyQuery &Q, unsigned MaxRecurse) {
4390  if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q))
4391  return C;
4392 
4393  if (Constant *C = simplifyFPBinop(Op0, Op1))
4394  return C;
4395 
4396  // fsub X, +0 ==> X
4397  if (match(Op1, m_PosZeroFP()))
4398  return Op0;
4399 
4400  // fsub X, -0 ==> X, when we know X is not -0
4401  if (match(Op1, m_NegZeroFP()) &&
4402  (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
4403  return Op0;
4404 
4405  // fsub -0.0, (fsub -0.0, X) ==> X
4406  // fsub -0.0, (fneg X) ==> X
4407  Value *X;
4408  if (match(Op0, m_NegZeroFP()) &&
4409  match(Op1, m_FNeg(m_Value(X))))
4410  return X;
4411 
4412  // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.
4413  // fsub 0.0, (fneg X) ==> X if signed zeros are ignored.
4414  if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) &&
4415  (match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) ||
4416  match(Op1, m_FNeg(m_Value(X)))))
4417  return X;
4418 
4419  // fsub nnan x, x ==> 0.0
4420  if (FMF.noNaNs() && Op0 == Op1)
4421  return Constant::getNullValue(Op0->getType());
4422 
4423  // Y - (Y - X) --> X
4424  // (X + Y) - Y --> X
4425  if (FMF.noSignedZeros() && FMF.allowReassoc() &&
4426  (match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) ||
4427  match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X)))))
4428  return X;
4429 
4430  return nullptr;
4431 }
4432 
4433 /// Given the operands for an FMul, see if we can fold the result
4435  const SimplifyQuery &Q, unsigned MaxRecurse) {
4436  if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q))
4437  return C;
4438 
4439  if (Constant *C = simplifyFPBinop(Op0, Op1))
4440  return C;
4441 
4442  // fmul X, 1.0 ==> X
4443  if (match(Op1, m_FPOne()))
4444  return Op0;
4445 
4446  // fmul nnan nsz X, 0 ==> 0
4447  if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZeroFP()))
4448  return ConstantFP::getNullValue(Op0->getType());
4449 
4450  // sqrt(X) * sqrt(X) --> X, if we can:
4451  // 1. Remove the intermediate rounding (reassociate).
4452  // 2. Ignore non-zero negative numbers because sqrt would produce NAN.
4453  // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0.
4454  Value *X;
4455  if (Op0 == Op1 && match(Op0, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))) &&
4456  FMF.allowReassoc() && FMF.noNaNs() && FMF.noSignedZeros())
4457  return X;
4458 
4459  return nullptr;
4460 }
4461 
4463  const SimplifyQuery &Q) {
4464  return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit);
4465 }
4466 
4467 
4469  const SimplifyQuery &Q) {
4470  return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit);
4471 }
4472 
4474  const SimplifyQuery &Q) {
4475  return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit);
4476 }
4477 
4479  const SimplifyQuery &Q, unsigned) {
4480  if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q))
4481  return C;
4482 
4483  if (Constant *C = simplifyFPBinop(Op0, Op1))
4484  return C;
4485 
4486  // X / 1.0 -> X
4487  if (match(Op1, m_FPOne()))
4488  return Op0;
4489 
4490  // 0 / X -> 0
4491  // Requires that NaNs are off (X could be zero) and signed zeroes are
4492  // ignored (X could be positive or negative, so the output sign is unknown).
4493  if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()))
4494  return ConstantFP::getNullValue(Op0->getType());
4495 
4496  if (FMF.noNaNs()) {
4497  // X / X -> 1.0 is legal when NaNs are ignored.
4498  // We can ignore infinities because INF/INF is NaN.
4499  if (Op0 == Op1)
4500  return ConstantFP::get(Op0->getType(), 1.0);
4501 
4502  // (X * Y) / Y --> X if we can reassociate to the above form.
4503  Value *X;
4504  if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1))))
4505  return X;
4506 
4507  // -X / X -> -1.0 and
4508  // X / -X -> -1.0 are legal when NaNs are ignored.
4509  // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored.
4510  if (match(Op0, m_FNegNSZ(m_Specific(Op1))) ||
4511  match(Op1, m_FNegNSZ(m_Specific(Op0))))
4512  return ConstantFP::get(Op0->getType(), -1.0);
4513  }
4514 
4515  return nullptr;
4516 }
4517 
4519  const SimplifyQuery &Q) {
4520  return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit);
4521 }
4522 
4524  const SimplifyQuery &Q, unsigned) {
4525  if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q))
4526  return C;
4527 
4528  if (Constant *C = simplifyFPBinop(Op0, Op1))
4529  return C;
4530 
4531  // Unlike fdiv, the result of frem always matches the sign of the dividend.
4532  // The constant match may include undef elements in a vector, so return a full
4533  // zero constant as the result.
4534  if (FMF.noNaNs()) {
4535  // +0 % X -> 0
4536  if (match(Op0, m_PosZeroFP()))
4537  return ConstantFP::getNullValue(Op0->getType());
4538  // -0 % X -> -0
4539  if (match(Op0, m_NegZeroFP()))
4540  return ConstantFP::getNegativeZero(Op0->getType());
4541  }
4542 
4543  return nullptr;
4544 }
4545 
4547  const SimplifyQuery &Q) {
4548  return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit);
4549 }
4550 
4551 //=== Helper functions for higher up the class hierarchy.
4552 
4553 /// Given the operand for a UnaryOperator, see if we can fold the result.
4554 /// If not, this returns null.
4555 static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q,
4556  unsigned MaxRecurse) {
4557  switch (Opcode) {
4558  case Instruction::FNeg:
4559  return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse);
4560  default:
4561  llvm_unreachable("Unexpected opcode");
4562  }
4563 }
4564 
4565 /// Given the operand for a UnaryOperator, see if we can fold the result.
4566 /// If not, this returns null.
4567 /// In contrast to SimplifyUnOp, try to use FastMathFlag when folding the
4568 /// result. In case we don't need FastMathFlags, simply fall to SimplifyUnOp.
4569 static Value *simplifyFPUnOp(unsigned Opcode, Value *Op,
4570  const FastMathFlags &FMF,
4571  const SimplifyQuery &Q, unsigned MaxRecurse) {
4572  switch (Opcode) {
4573  case Instruction::FNeg:
4574  return simplifyFNegInst(Op, FMF, Q, MaxRecurse);
4575  default:
4576  return simplifyUnOp(Opcode, Op, Q, MaxRecurse);
4577  }
4578 }
4579 
4580 Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) {
4581  return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit);
4582 }
4583 
4585  const SimplifyQuery &Q) {
4586  return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit);
4587 }
4588 
4589 /// Given operands for a BinaryOperator, see if we can fold the result.
4590 /// If not, this returns null.
4591 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4592  const SimplifyQuery &Q, unsigned MaxRecurse) {
4593  switch (Opcode) {
4594  case Instruction::Add:
4595  return SimplifyAddInst(LHS, RHS, false, false, Q, MaxRecurse);
4596  case Instruction::Sub:
4597  return SimplifySubInst(LHS, RHS, false, false, Q, MaxRecurse);
4598  case Instruction::Mul:
4599  return SimplifyMulInst(LHS, RHS, Q, MaxRecurse);
4600  case Instruction::SDiv:
4601  return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
4602  case Instruction::UDiv:
4603  return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
4604  case Instruction::SRem:
4605  return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
4606  case Instruction::URem:
4607  return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
4608  case Instruction::Shl:
4609  return SimplifyShlInst(LHS, RHS, false, false, Q, MaxRecurse);
4610  case Instruction::LShr:
4611  return SimplifyLShrInst(LHS, RHS, false, Q, MaxRecurse);
4612  case Instruction::AShr:
4613  return SimplifyAShrInst(LHS, RHS, false, Q, MaxRecurse);
4614  case Instruction::And:
4615  return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
4616  case Instruction::Or:
4617  return SimplifyOrInst(LHS, RHS, Q, MaxRecurse);
4618  case Instruction::Xor:
4619  return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
4620  case Instruction::FAdd:
4621  return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4622  case Instruction::FSub:
4623  return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4624  case Instruction::FMul:
4625  return SimplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4626  case Instruction::FDiv:
4627  return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4628  case Instruction::FRem:
4629  return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4630  default:
4631  llvm_unreachable("Unexpected opcode");
4632  }
4633 }
4634 
4635 /// Given operands for a BinaryOperator, see if we can fold the result.
4636 /// If not, this returns null.
4637 /// In contrast to SimplifyBinOp, try to use FastMathFlag when folding the
4638 /// result. In case we don't need FastMathFlags, simply fall to SimplifyBinOp.
4639 static Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4640  const FastMathFlags &FMF, const SimplifyQuery &Q,
4641  unsigned MaxRecurse) {
4642  switch (Opcode) {
4643  case Instruction::FAdd:
4644  return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse);
4645  case Instruction::FSub:
4646  return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse);
4647  case Instruction::FMul:
4648  return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse);
4649  case Instruction::FDiv:
4650  return SimplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse);
4651  default:
4652  return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
4653  }
4654 }
4655 
4656 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4657  const SimplifyQuery &Q) {
4658  return ::SimplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit);
4659 }
4660 
4661 Value *llvm::SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4662  FastMathFlags FMF, const SimplifyQuery &Q) {
4663  return ::SimplifyFPBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit);
4664 }
4665 
4666 /// Given operands for a CmpInst, see if we can fold the result.
4667 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
4668  const SimplifyQuery &Q, unsigned MaxRecurse) {
4670  return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
4671  return SimplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4672 }
4673 
4674 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
4675  const SimplifyQuery &Q) {
4676  return ::SimplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
4677 }
4678 
4680  switch (ID) {
4681  default: return false;
4682 
4683  // Unary idempotent: f(f(x)) = f(x)
4684  case Intrinsic::fabs:
4685  case Intrinsic::floor:
4686  case Intrinsic::ceil:
4687  case Intrinsic::trunc:
4688  case Intrinsic::rint:
4689  case Intrinsic::nearbyint:
4690  case Intrinsic::round:
4691  case Intrinsic::canonicalize:
4692  return true;
4693  }
4694 }
4695 
4697  const DataLayout &DL) {
4698  GlobalValue *PtrSym;
4699  APInt PtrOffset;
4700  if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL))
4701  return nullptr;
4702 
4703  Type *Int8PtrTy = Type::getInt8PtrTy(Ptr->getContext());
4705  Type *Int32PtrTy = Int32Ty->getPointerTo();
4706  Type *Int64Ty = Type::getInt64Ty(Ptr->getContext());
4707 
4708  auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset);
4709  if (!OffsetConstInt || OffsetConstInt->getType()->getBitWidth() > 64)
4710  return nullptr;
4711 
4712  uint64_t OffsetInt = OffsetConstInt->getSExtValue();
4713  if (OffsetInt % 4 != 0)
4714  return nullptr;
4715 
4717  Int32Ty, ConstantExpr::getBitCast(Ptr, Int32PtrTy),
4718  ConstantInt::get(Int64Ty, OffsetInt / 4));
4719  Constant *Loaded = ConstantFoldLoadFromConstPtr(C, Int32Ty, DL);
4720  if (!Loaded)
4721  return nullptr;
4722 
4723  auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded);
4724  if (!LoadedCE)
4725  return nullptr;
4726 
4727  if (LoadedCE->getOpcode() == Instruction::Trunc) {
4728  LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
4729  if (!LoadedCE)
4730  return nullptr;
4731  }
4732 
4733  if (LoadedCE->getOpcode() != Instruction::Sub)
4734  return nullptr;
4735 
4736  auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
4737  if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt)
4738  return nullptr;
4739  auto *LoadedLHSPtr = LoadedLHS->getOperand(0);
4740 
4741  Constant *LoadedRHS = LoadedCE->getOperand(1);
4742  GlobalValue *LoadedRHSSym;
4743  APInt LoadedRHSOffset;
4744  if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset,
4745  DL) ||
4746  PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset)
4747  return nullptr;
4748 
4749  return ConstantExpr::getBitCast(LoadedLHSPtr, Int8PtrTy);
4750 }
4751 
4753  const SimplifyQuery &Q) {
4754  // Idempotent functions return the same result when called repeatedly.
4755  Intrinsic::ID IID = F->getIntrinsicID();
4756  if (IsIdempotent(IID))
4757  if (auto *II = dyn_cast<IntrinsicInst>(Op0))
4758  if (II->getIntrinsicID() == IID)
4759  return II;
4760 
4761  Value *X;
4762  switch (IID) {
4763  case Intrinsic::fabs:
4764  if (SignBitMustBeZero(Op0, Q.TLI)) return Op0;
4765  break;
4766  case Intrinsic::bswap:
4767  // bswap(bswap(x)) -> x
4768  if (match(Op0, m_BSwap(m_Value(X)))) return X;
4769  break;
4770  case Intrinsic::bitreverse:
4771  // bitreverse(bitreverse(x)) -> x
4772  if (match(Op0, m_BitReverse(m_Value(X)))) return X;
4773  break;
4774  case Intrinsic::exp:
4775  // exp(log(x)) -> x
4776  if (Q.CxtI->hasAllowReassoc() &&
4777  match(Op0, m_Intrinsic<Intrinsic::log>(m_Value(X)))) return X;
4778  break;
4779  case Intrinsic::exp2: