LLVM  7.0.0svn
InstructionSimplify.cpp
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1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements routines for folding instructions into simpler forms
11 // that do not require creating new instructions. This does constant folding
12 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
13 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
14 // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
15 // simplified: This is usually true and assuming it simplifies the logic (if
16 // they have not been simplified then results are correct but maybe suboptimal).
17 //
18 //===----------------------------------------------------------------------===//
19 
21 #include "llvm/ADT/SetVector.h"
22 #include "llvm/ADT/Statistic.h"
32 #include "llvm/IR/ConstantRange.h"
33 #include "llvm/IR/DataLayout.h"
34 #include "llvm/IR/Dominators.h"
36 #include "llvm/IR/GlobalAlias.h"
37 #include "llvm/IR/Operator.h"
38 #include "llvm/IR/PatternMatch.h"
39 #include "llvm/IR/ValueHandle.h"
40 #include "llvm/Support/KnownBits.h"
41 #include <algorithm>
42 using namespace llvm;
43 using namespace llvm::PatternMatch;
44 
45 #define DEBUG_TYPE "instsimplify"
46 
47 enum { RecursionLimit = 3 };
48 
49 STATISTIC(NumExpand, "Number of expansions");
50 STATISTIC(NumReassoc, "Number of reassociations");
51 
52 static Value *SimplifyAndInst(Value *, Value *, const SimplifyQuery &, unsigned);
53 static Value *SimplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &,
54  unsigned);
55 static Value *SimplifyFPBinOp(unsigned, Value *, Value *, const FastMathFlags &,
56  const SimplifyQuery &, unsigned);
57 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &,
58  unsigned);
59 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
60  const SimplifyQuery &Q, unsigned MaxRecurse);
61 static Value *SimplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned);
62 static Value *SimplifyXorInst(Value *, Value *, const SimplifyQuery &, unsigned);
63 static Value *SimplifyCastInst(unsigned, Value *, Type *,
64  const SimplifyQuery &, unsigned);
65 
66 /// For a boolean type or a vector of boolean type, return false or a vector
67 /// with every element false.
68 static Constant *getFalse(Type *Ty) {
69  return ConstantInt::getFalse(Ty);
70 }
71 
72 /// For a boolean type or a vector of boolean type, return true or a vector
73 /// with every element true.
74 static Constant *getTrue(Type *Ty) {
75  return ConstantInt::getTrue(Ty);
76 }
77 
78 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
79 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
80  Value *RHS) {
81  CmpInst *Cmp = dyn_cast<CmpInst>(V);
82  if (!Cmp)
83  return false;
84  CmpInst::Predicate CPred = Cmp->getPredicate();
85  Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
86  if (CPred == Pred && CLHS == LHS && CRHS == RHS)
87  return true;
88  return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
89  CRHS == LHS;
90 }
91 
92 /// Does the given value dominate the specified phi node?
93 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
95  if (!I)
96  // Arguments and constants dominate all instructions.
97  return true;
98 
99  // If we are processing instructions (and/or basic blocks) that have not been
100  // fully added to a function, the parent nodes may still be null. Simply
101  // return the conservative answer in these cases.
102  if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
103  return false;
104 
105  // If we have a DominatorTree then do a precise test.
106  if (DT)
107  return DT->dominates(I, P);
108 
109  // Otherwise, if the instruction is in the entry block and is not an invoke,
110  // then it obviously dominates all phi nodes.
111  if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
112  !isa<InvokeInst>(I))
113  return true;
114 
115  return false;
116 }
117 
118 /// Simplify "A op (B op' C)" by distributing op over op', turning it into
119 /// "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
120 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
121 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
122 /// Returns the simplified value, or null if no simplification was performed.
124  Instruction::BinaryOps OpcodeToExpand,
125  const SimplifyQuery &Q, unsigned MaxRecurse) {
126  // Recursion is always used, so bail out at once if we already hit the limit.
127  if (!MaxRecurse--)
128  return nullptr;
129 
130  // Check whether the expression has the form "(A op' B) op C".
131  if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
132  if (Op0->getOpcode() == OpcodeToExpand) {
133  // It does! Try turning it into "(A op C) op' (B op C)".
134  Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
135  // Do "A op C" and "B op C" both simplify?
136  if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
137  if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
138  // They do! Return "L op' R" if it simplifies or is already available.
139  // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
140  if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
141  && L == B && R == A)) {
142  ++NumExpand;
143  return LHS;
144  }
145  // Otherwise return "L op' R" if it simplifies.
146  if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
147  ++NumExpand;
148  return V;
149  }
150  }
151  }
152 
153  // Check whether the expression has the form "A op (B op' C)".
154  if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
155  if (Op1->getOpcode() == OpcodeToExpand) {
156  // It does! Try turning it into "(A op B) op' (A op C)".
157  Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
158  // Do "A op B" and "A op C" both simplify?
159  if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
160  if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
161  // They do! Return "L op' R" if it simplifies or is already available.
162  // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
163  if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
164  && L == C && R == B)) {
165  ++NumExpand;
166  return RHS;
167  }
168  // Otherwise return "L op' R" if it simplifies.
169  if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
170  ++NumExpand;
171  return V;
172  }
173  }
174  }
175 
176  return nullptr;
177 }
178 
179 /// Generic simplifications for associative binary operations.
180 /// Returns the simpler value, or null if none was found.
182  Value *LHS, Value *RHS,
183  const SimplifyQuery &Q,
184  unsigned MaxRecurse) {
185  assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
186 
187  // Recursion is always used, so bail out at once if we already hit the limit.
188  if (!MaxRecurse--)
189  return nullptr;
190 
193 
194  // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
195  if (Op0 && Op0->getOpcode() == Opcode) {
196  Value *A = Op0->getOperand(0);
197  Value *B = Op0->getOperand(1);
198  Value *C = RHS;
199 
200  // Does "B op C" simplify?
201  if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
202  // It does! Return "A op V" if it simplifies or is already available.
203  // If V equals B then "A op V" is just the LHS.
204  if (V == B) return LHS;
205  // Otherwise return "A op V" if it simplifies.
206  if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
207  ++NumReassoc;
208  return W;
209  }
210  }
211  }
212 
213  // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
214  if (Op1 && Op1->getOpcode() == Opcode) {
215  Value *A = LHS;
216  Value *B = Op1->getOperand(0);
217  Value *C = Op1->getOperand(1);
218 
219  // Does "A op B" simplify?
220  if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
221  // It does! Return "V op C" if it simplifies or is already available.
222  // If V equals B then "V op C" is just the RHS.
223  if (V == B) return RHS;
224  // Otherwise return "V op C" if it simplifies.
225  if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
226  ++NumReassoc;
227  return W;
228  }
229  }
230  }
231 
232  // The remaining transforms require commutativity as well as associativity.
233  if (!Instruction::isCommutative(Opcode))
234  return nullptr;
235 
236  // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
237  if (Op0 && Op0->getOpcode() == Opcode) {
238  Value *A = Op0->getOperand(0);
239  Value *B = Op0->getOperand(1);
240  Value *C = RHS;
241 
242  // Does "C op A" simplify?
243  if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
244  // It does! Return "V op B" if it simplifies or is already available.
245  // If V equals A then "V op B" is just the LHS.
246  if (V == A) return LHS;
247  // Otherwise return "V op B" if it simplifies.
248  if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
249  ++NumReassoc;
250  return W;
251  }
252  }
253  }
254 
255  // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
256  if (Op1 && Op1->getOpcode() == Opcode) {
257  Value *A = LHS;
258  Value *B = Op1->getOperand(0);
259  Value *C = Op1->getOperand(1);
260 
261  // Does "C op A" simplify?
262  if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
263  // It does! Return "B op V" if it simplifies or is already available.
264  // If V equals C then "B op V" is just the RHS.
265  if (V == C) return RHS;
266  // Otherwise return "B op V" if it simplifies.
267  if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
268  ++NumReassoc;
269  return W;
270  }
271  }
272  }
273 
274  return nullptr;
275 }
276 
277 /// In the case of a binary operation with a select instruction as an operand,
278 /// try to simplify the binop by seeing whether evaluating it on both branches
279 /// of the select results in the same value. Returns the common value if so,
280 /// otherwise returns null.
282  Value *RHS, const SimplifyQuery &Q,
283  unsigned MaxRecurse) {
284  // Recursion is always used, so bail out at once if we already hit the limit.
285  if (!MaxRecurse--)
286  return nullptr;
287 
288  SelectInst *SI;
289  if (isa<SelectInst>(LHS)) {
290  SI = cast<SelectInst>(LHS);
291  } else {
292  assert(isa<SelectInst>(RHS) && "No select instruction operand!");
293  SI = cast<SelectInst>(RHS);
294  }
295 
296  // Evaluate the BinOp on the true and false branches of the select.
297  Value *TV;
298  Value *FV;
299  if (SI == LHS) {
300  TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
301  FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
302  } else {
303  TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
304  FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
305  }
306 
307  // If they simplified to the same value, then return the common value.
308  // If they both failed to simplify then return null.
309  if (TV == FV)
310  return TV;
311 
312  // If one branch simplified to undef, return the other one.
313  if (TV && isa<UndefValue>(TV))
314  return FV;
315  if (FV && isa<UndefValue>(FV))
316  return TV;
317 
318  // If applying the operation did not change the true and false select values,
319  // then the result of the binop is the select itself.
320  if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
321  return SI;
322 
323  // If one branch simplified and the other did not, and the simplified
324  // value is equal to the unsimplified one, return the simplified value.
325  // For example, select (cond, X, X & Z) & Z -> X & Z.
326  if ((FV && !TV) || (TV && !FV)) {
327  // Check that the simplified value has the form "X op Y" where "op" is the
328  // same as the original operation.
329  Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
330  if (Simplified && Simplified->getOpcode() == unsigned(Opcode)) {
331  // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
332  // We already know that "op" is the same as for the simplified value. See
333  // if the operands match too. If so, return the simplified value.
334  Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
335  Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
336  Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
337  if (Simplified->getOperand(0) == UnsimplifiedLHS &&
338  Simplified->getOperand(1) == UnsimplifiedRHS)
339  return Simplified;
340  if (Simplified->isCommutative() &&
341  Simplified->getOperand(1) == UnsimplifiedLHS &&
342  Simplified->getOperand(0) == UnsimplifiedRHS)
343  return Simplified;
344  }
345  }
346 
347  return nullptr;
348 }
349 
350 /// In the case of a comparison with a select instruction, try to simplify the
351 /// comparison by seeing whether both branches of the select result in the same
352 /// value. Returns the common value if so, otherwise returns null.
354  Value *RHS, const SimplifyQuery &Q,
355  unsigned MaxRecurse) {
356  // Recursion is always used, so bail out at once if we already hit the limit.
357  if (!MaxRecurse--)
358  return nullptr;
359 
360  // Make sure the select is on the LHS.
361  if (!isa<SelectInst>(LHS)) {
362  std::swap(LHS, RHS);
363  Pred = CmpInst::getSwappedPredicate(Pred);
364  }
365  assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
366  SelectInst *SI = cast<SelectInst>(LHS);
367  Value *Cond = SI->getCondition();
368  Value *TV = SI->getTrueValue();
369  Value *FV = SI->getFalseValue();
370 
371  // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
372  // Does "cmp TV, RHS" simplify?
373  Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
374  if (TCmp == Cond) {
375  // It not only simplified, it simplified to the select condition. Replace
376  // it with 'true'.
377  TCmp = getTrue(Cond->getType());
378  } else if (!TCmp) {
379  // It didn't simplify. However if "cmp TV, RHS" is equal to the select
380  // condition then we can replace it with 'true'. Otherwise give up.
381  if (!isSameCompare(Cond, Pred, TV, RHS))
382  return nullptr;
383  TCmp = getTrue(Cond->getType());
384  }
385 
386  // Does "cmp FV, RHS" simplify?
387  Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
388  if (FCmp == Cond) {
389  // It not only simplified, it simplified to the select condition. Replace
390  // it with 'false'.
391  FCmp = getFalse(Cond->getType());
392  } else if (!FCmp) {
393  // It didn't simplify. However if "cmp FV, RHS" is equal to the select
394  // condition then we can replace it with 'false'. Otherwise give up.
395  if (!isSameCompare(Cond, Pred, FV, RHS))
396  return nullptr;
397  FCmp = getFalse(Cond->getType());
398  }
399 
400  // If both sides simplified to the same value, then use it as the result of
401  // the original comparison.
402  if (TCmp == FCmp)
403  return TCmp;
404 
405  // The remaining cases only make sense if the select condition has the same
406  // type as the result of the comparison, so bail out if this is not so.
407  if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
408  return nullptr;
409  // If the false value simplified to false, then the result of the compare
410  // is equal to "Cond && TCmp". This also catches the case when the false
411  // value simplified to false and the true value to true, returning "Cond".
412  if (match(FCmp, m_Zero()))
413  if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
414  return V;
415  // If the true value simplified to true, then the result of the compare
416  // is equal to "Cond || FCmp".
417  if (match(TCmp, m_One()))
418  if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
419  return V;
420  // Finally, if the false value simplified to true and the true value to
421  // false, then the result of the compare is equal to "!Cond".
422  if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
423  if (Value *V =
424  SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
425  Q, MaxRecurse))
426  return V;
427 
428  return nullptr;
429 }
430 
431 /// In the case of a binary operation with an operand that is a PHI instruction,
432 /// try to simplify the binop by seeing whether evaluating it on the incoming
433 /// phi values yields the same result for every value. If so returns the common
434 /// value, otherwise returns null.
436  Value *RHS, const SimplifyQuery &Q,
437  unsigned MaxRecurse) {
438  // Recursion is always used, so bail out at once if we already hit the limit.
439  if (!MaxRecurse--)
440  return nullptr;
441 
442  PHINode *PI;
443  if (isa<PHINode>(LHS)) {
444  PI = cast<PHINode>(LHS);
445  // Bail out if RHS and the phi may be mutually interdependent due to a loop.
446  if (!ValueDominatesPHI(RHS, PI, Q.DT))
447  return nullptr;
448  } else {
449  assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
450  PI = cast<PHINode>(RHS);
451  // Bail out if LHS and the phi may be mutually interdependent due to a loop.
452  if (!ValueDominatesPHI(LHS, PI, Q.DT))
453  return nullptr;
454  }
455 
456  // Evaluate the BinOp on the incoming phi values.
457  Value *CommonValue = nullptr;
458  for (Value *Incoming : PI->incoming_values()) {
459  // If the incoming value is the phi node itself, it can safely be skipped.
460  if (Incoming == PI) continue;
461  Value *V = PI == LHS ?
462  SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
463  SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
464  // If the operation failed to simplify, or simplified to a different value
465  // to previously, then give up.
466  if (!V || (CommonValue && V != CommonValue))
467  return nullptr;
468  CommonValue = V;
469  }
470 
471  return CommonValue;
472 }
473 
474 /// In the case of a comparison with a PHI instruction, try to simplify the
475 /// comparison by seeing whether comparing with all of the incoming phi values
476 /// yields the same result every time. If so returns the common result,
477 /// otherwise returns null.
479  const SimplifyQuery &Q, unsigned MaxRecurse) {
480  // Recursion is always used, so bail out at once if we already hit the limit.
481  if (!MaxRecurse--)
482  return nullptr;
483 
484  // Make sure the phi is on the LHS.
485  if (!isa<PHINode>(LHS)) {
486  std::swap(LHS, RHS);
487  Pred = CmpInst::getSwappedPredicate(Pred);
488  }
489  assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
490  PHINode *PI = cast<PHINode>(LHS);
491 
492  // Bail out if RHS and the phi may be mutually interdependent due to a loop.
493  if (!ValueDominatesPHI(RHS, PI, Q.DT))
494  return nullptr;
495 
496  // Evaluate the BinOp on the incoming phi values.
497  Value *CommonValue = nullptr;
498  for (Value *Incoming : PI->incoming_values()) {
499  // If the incoming value is the phi node itself, it can safely be skipped.
500  if (Incoming == PI) continue;
501  Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
502  // If the operation failed to simplify, or simplified to a different value
503  // to previously, then give up.
504  if (!V || (CommonValue && V != CommonValue))
505  return nullptr;
506  CommonValue = V;
507  }
508 
509  return CommonValue;
510 }
511 
513  Value *&Op0, Value *&Op1,
514  const SimplifyQuery &Q) {
515  if (auto *CLHS = dyn_cast<Constant>(Op0)) {
516  if (auto *CRHS = dyn_cast<Constant>(Op1))
517  return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL);
518 
519  // Canonicalize the constant to the RHS if this is a commutative operation.
520  if (Instruction::isCommutative(Opcode))
521  std::swap(Op0, Op1);
522  }
523  return nullptr;
524 }
525 
526 /// Given operands for an Add, see if we can fold the result.
527 /// If not, this returns null.
528 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
529  const SimplifyQuery &Q, unsigned MaxRecurse) {
530  if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q))
531  return C;
532 
533  // X + undef -> undef
534  if (match(Op1, m_Undef()))
535  return Op1;
536 
537  // X + 0 -> X
538  if (match(Op1, m_Zero()))
539  return Op0;
540 
541  // X + (Y - X) -> Y
542  // (Y - X) + X -> Y
543  // Eg: X + -X -> 0
544  Value *Y = nullptr;
545  if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
546  match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
547  return Y;
548 
549  // X + ~X -> -1 since ~X = -X-1
550  Type *Ty = Op0->getType();
551  if (match(Op0, m_Not(m_Specific(Op1))) ||
552  match(Op1, m_Not(m_Specific(Op0))))
553  return Constant::getAllOnesValue(Ty);
554 
555  // add nsw/nuw (xor Y, signmask), signmask --> Y
556  // The no-wrapping add guarantees that the top bit will be set by the add.
557  // Therefore, the xor must be clearing the already set sign bit of Y.
558  if ((isNSW || isNUW) && match(Op1, m_SignMask()) &&
559  match(Op0, m_Xor(m_Value(Y), m_SignMask())))
560  return Y;
561 
562  /// i1 add -> xor.
563  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
564  if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
565  return V;
566 
567  // Try some generic simplifications for associative operations.
568  if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
569  MaxRecurse))
570  return V;
571 
572  // Threading Add over selects and phi nodes is pointless, so don't bother.
573  // Threading over the select in "A + select(cond, B, C)" means evaluating
574  // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
575  // only if B and C are equal. If B and C are equal then (since we assume
576  // that operands have already been simplified) "select(cond, B, C)" should
577  // have been simplified to the common value of B and C already. Analysing
578  // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
579  // for threading over phi nodes.
580 
581  return nullptr;
582 }
583 
584 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
585  const SimplifyQuery &Query) {
586  return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query, RecursionLimit);
587 }
588 
589 /// \brief Compute the base pointer and cumulative constant offsets for V.
590 ///
591 /// This strips all constant offsets off of V, leaving it the base pointer, and
592 /// accumulates the total constant offset applied in the returned constant. It
593 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
594 /// no constant offsets applied.
595 ///
596 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
597 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
598 /// folding.
600  bool AllowNonInbounds = false) {
602 
603  Type *IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType();
604  APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
605 
606  // Even though we don't look through PHI nodes, we could be called on an
607  // instruction in an unreachable block, which may be on a cycle.
608  SmallPtrSet<Value *, 4> Visited;
609  Visited.insert(V);
610  do {
611  if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
612  if ((!AllowNonInbounds && !GEP->isInBounds()) ||
613  !GEP->accumulateConstantOffset(DL, Offset))
614  break;
615  V = GEP->getPointerOperand();
616  } else if (Operator::getOpcode(V) == Instruction::BitCast) {
617  V = cast<Operator>(V)->getOperand(0);
618  } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
619  if (GA->isInterposable())
620  break;
621  V = GA->getAliasee();
622  } else {
623  if (auto CS = CallSite(V))
624  if (Value *RV = CS.getReturnedArgOperand()) {
625  V = RV;
626  continue;
627  }
628  break;
629  }
630  assert(V->getType()->isPtrOrPtrVectorTy() && "Unexpected operand type!");
631  } while (Visited.insert(V).second);
632 
633  Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
634  if (V->getType()->isVectorTy())
636  OffsetIntPtr);
637  return OffsetIntPtr;
638 }
639 
640 /// \brief Compute the constant difference between two pointer values.
641 /// If the difference is not a constant, returns zero.
643  Value *RHS) {
644  Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
645  Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
646 
647  // If LHS and RHS are not related via constant offsets to the same base
648  // value, there is nothing we can do here.
649  if (LHS != RHS)
650  return nullptr;
651 
652  // Otherwise, the difference of LHS - RHS can be computed as:
653  // LHS - RHS
654  // = (LHSOffset + Base) - (RHSOffset + Base)
655  // = LHSOffset - RHSOffset
656  return ConstantExpr::getSub(LHSOffset, RHSOffset);
657 }
658 
659 /// Given operands for a Sub, see if we can fold the result.
660 /// If not, this returns null.
661 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
662  const SimplifyQuery &Q, unsigned MaxRecurse) {
663  if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q))
664  return C;
665 
666  // X - undef -> undef
667  // undef - X -> undef
668  if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
669  return UndefValue::get(Op0->getType());
670 
671  // X - 0 -> X
672  if (match(Op1, m_Zero()))
673  return Op0;
674 
675  // X - X -> 0
676  if (Op0 == Op1)
677  return Constant::getNullValue(Op0->getType());
678 
679  // Is this a negation?
680  if (match(Op0, m_Zero())) {
681  // 0 - X -> 0 if the sub is NUW.
682  if (isNUW)
683  return Op0;
684 
685  KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
686  if (Known.Zero.isMaxSignedValue()) {
687  // Op1 is either 0 or the minimum signed value. If the sub is NSW, then
688  // Op1 must be 0 because negating the minimum signed value is undefined.
689  if (isNSW)
690  return Op0;
691 
692  // 0 - X -> X if X is 0 or the minimum signed value.
693  return Op1;
694  }
695  }
696 
697  // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
698  // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
699  Value *X = nullptr, *Y = nullptr, *Z = Op1;
700  if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
701  // See if "V === Y - Z" simplifies.
702  if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
703  // It does! Now see if "X + V" simplifies.
704  if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
705  // It does, we successfully reassociated!
706  ++NumReassoc;
707  return W;
708  }
709  // See if "V === X - Z" simplifies.
710  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
711  // It does! Now see if "Y + V" simplifies.
712  if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
713  // It does, we successfully reassociated!
714  ++NumReassoc;
715  return W;
716  }
717  }
718 
719  // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
720  // For example, X - (X + 1) -> -1
721  X = Op0;
722  if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
723  // See if "V === X - Y" simplifies.
724  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
725  // It does! Now see if "V - Z" simplifies.
726  if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
727  // It does, we successfully reassociated!
728  ++NumReassoc;
729  return W;
730  }
731  // See if "V === X - Z" simplifies.
732  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
733  // It does! Now see if "V - Y" simplifies.
734  if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
735  // It does, we successfully reassociated!
736  ++NumReassoc;
737  return W;
738  }
739  }
740 
741  // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
742  // For example, X - (X - Y) -> Y.
743  Z = Op0;
744  if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
745  // See if "V === Z - X" simplifies.
746  if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
747  // It does! Now see if "V + Y" simplifies.
748  if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
749  // It does, we successfully reassociated!
750  ++NumReassoc;
751  return W;
752  }
753 
754  // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
755  if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
756  match(Op1, m_Trunc(m_Value(Y))))
757  if (X->getType() == Y->getType())
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 "trunc V" simplifies.
761  if (Value *W = SimplifyCastInst(Instruction::Trunc, V, Op0->getType(),
762  Q, MaxRecurse - 1))
763  // It does, return the simplified "trunc V".
764  return W;
765 
766  // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
767  if (match(Op0, m_PtrToInt(m_Value(X))) &&
768  match(Op1, m_PtrToInt(m_Value(Y))))
769  if (Constant *Result = computePointerDifference(Q.DL, X, Y))
770  return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
771 
772  // i1 sub -> xor.
773  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
774  if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
775  return V;
776 
777  // Threading Sub over selects and phi nodes is pointless, so don't bother.
778  // Threading over the select in "A - select(cond, B, C)" means evaluating
779  // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
780  // only if B and C are equal. If B and C are equal then (since we assume
781  // that operands have already been simplified) "select(cond, B, C)" should
782  // have been simplified to the common value of B and C already. Analysing
783  // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
784  // for threading over phi nodes.
785 
786  return nullptr;
787 }
788 
789 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
790  const SimplifyQuery &Q) {
791  return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
792 }
793 
794 /// Given operands for a Mul, see if we can fold the result.
795 /// If not, this returns null.
796 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
797  unsigned MaxRecurse) {
798  if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q))
799  return C;
800 
801  // X * undef -> 0
802  if (match(Op1, m_Undef()))
803  return Constant::getNullValue(Op0->getType());
804 
805  // X * 0 -> 0
806  if (match(Op1, m_Zero()))
807  return Op1;
808 
809  // X * 1 -> X
810  if (match(Op1, m_One()))
811  return Op0;
812 
813  // (X / Y) * Y -> X if the division is exact.
814  Value *X = nullptr;
815  if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
816  match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
817  return X;
818 
819  // i1 mul -> and.
820  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
821  if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
822  return V;
823 
824  // Try some generic simplifications for associative operations.
825  if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
826  MaxRecurse))
827  return V;
828 
829  // Mul distributes over Add. Try some generic simplifications based on this.
830  if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
831  Q, MaxRecurse))
832  return V;
833 
834  // If the operation is with the result of a select instruction, check whether
835  // operating on either branch of the select always yields the same value.
836  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
837  if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
838  MaxRecurse))
839  return V;
840 
841  // If the operation is with the result of a phi instruction, check whether
842  // operating on all incoming values of the phi always yields the same value.
843  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
844  if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
845  MaxRecurse))
846  return V;
847 
848  return nullptr;
849 }
850 
853 }
854 
855 /// Check for common or similar folds of integer division or integer remainder.
856 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem).
857 static Value *simplifyDivRem(Value *Op0, Value *Op1, bool IsDiv) {
858  Type *Ty = Op0->getType();
859 
860  // X / undef -> undef
861  // X % undef -> undef
862  if (match(Op1, m_Undef()))
863  return Op1;
864 
865  // X / 0 -> undef
866  // X % 0 -> undef
867  // We don't need to preserve faults!
868  if (match(Op1, m_Zero()))
869  return UndefValue::get(Ty);
870 
871  // If any element of a constant divisor vector is zero or undef, the whole op
872  // is undef.
873  auto *Op1C = dyn_cast<Constant>(Op1);
874  if (Op1C && Ty->isVectorTy()) {
875  unsigned NumElts = Ty->getVectorNumElements();
876  for (unsigned i = 0; i != NumElts; ++i) {
877  Constant *Elt = Op1C->getAggregateElement(i);
878  if (Elt && (Elt->isNullValue() || isa<UndefValue>(Elt)))
879  return UndefValue::get(Ty);
880  }
881  }
882 
883  // undef / X -> 0
884  // undef % X -> 0
885  if (match(Op0, m_Undef()))
886  return Constant::getNullValue(Ty);
887 
888  // 0 / X -> 0
889  // 0 % X -> 0
890  if (match(Op0, m_Zero()))
891  return Op0;
892 
893  // X / X -> 1
894  // X % X -> 0
895  if (Op0 == Op1)
896  return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty);
897 
898  // X / 1 -> X
899  // X % 1 -> 0
900  // If this is a boolean op (single-bit element type), we can't have
901  // division-by-zero or remainder-by-zero, so assume the divisor is 1.
902  if (match(Op1, m_One()) || Ty->isIntOrIntVectorTy(1))
903  return IsDiv ? Op0 : Constant::getNullValue(Ty);
904 
905  return nullptr;
906 }
907 
908 /// Given a predicate and two operands, return true if the comparison is true.
909 /// This is a helper for div/rem simplification where we return some other value
910 /// when we can prove a relationship between the operands.
911 static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS,
912  const SimplifyQuery &Q, unsigned MaxRecurse) {
913  Value *V = SimplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse);
914  Constant *C = dyn_cast_or_null<Constant>(V);
915  return (C && C->isAllOnesValue());
916 }
917 
918 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer
919 /// to simplify X % Y to X.
920 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q,
921  unsigned MaxRecurse, bool IsSigned) {
922  // Recursion is always used, so bail out at once if we already hit the limit.
923  if (!MaxRecurse--)
924  return false;
925 
926  if (IsSigned) {
927  // |X| / |Y| --> 0
928  //
929  // We require that 1 operand is a simple constant. That could be extended to
930  // 2 variables if we computed the sign bit for each.
931  //
932  // Make sure that a constant is not the minimum signed value because taking
933  // the abs() of that is undefined.
934  Type *Ty = X->getType();
935  const APInt *C;
936  if (match(X, m_APInt(C)) && !C->isMinSignedValue()) {
937  // Is the variable divisor magnitude always greater than the constant
938  // dividend magnitude?
939  // |Y| > |C| --> Y < -abs(C) or Y > abs(C)
940  Constant *PosDividendC = ConstantInt::get(Ty, C->abs());
941  Constant *NegDividendC = ConstantInt::get(Ty, -C->abs());
942  if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) ||
943  isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse))
944  return true;
945  }
946  if (match(Y, m_APInt(C))) {
947  // Special-case: we can't take the abs() of a minimum signed value. If
948  // that's the divisor, then all we have to do is prove that the dividend
949  // is also not the minimum signed value.
950  if (C->isMinSignedValue())
951  return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse);
952 
953  // Is the variable dividend magnitude always less than the constant
954  // divisor magnitude?
955  // |X| < |C| --> X > -abs(C) and X < abs(C)
956  Constant *PosDivisorC = ConstantInt::get(Ty, C->abs());
957  Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs());
958  if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) &&
959  isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse))
960  return true;
961  }
962  return false;
963  }
964 
965  // IsSigned == false.
966  // Is the dividend unsigned less than the divisor?
967  return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse);
968 }
969 
970 /// These are simplifications common to SDiv and UDiv.
972  const SimplifyQuery &Q, unsigned MaxRecurse) {
973  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
974  return C;
975 
976  if (Value *V = simplifyDivRem(Op0, Op1, true))
977  return V;
978 
979  bool IsSigned = Opcode == Instruction::SDiv;
980 
981  // (X * Y) / Y -> X if the multiplication does not overflow.
982  Value *X;
983  if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) {
984  auto *Mul = cast<OverflowingBinaryOperator>(Op0);
985  // If the Mul does not overflow, then we are good to go.
986  if ((IsSigned && Mul->hasNoSignedWrap()) ||
987  (!IsSigned && Mul->hasNoUnsignedWrap()))
988  return X;
989  // If X has the form X = A / Y, then X * Y cannot overflow.
990  if ((IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) ||
991  (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1)))))
992  return X;
993  }
994 
995  // (X rem Y) / Y -> 0
996  if ((IsSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
997  (!IsSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
998  return Constant::getNullValue(Op0->getType());
999 
1000  // (X /u C1) /u C2 -> 0 if C1 * C2 overflow
1001  ConstantInt *C1, *C2;
1002  if (!IsSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
1003  match(Op1, m_ConstantInt(C2))) {
1004  bool Overflow;
1005  (void)C1->getValue().umul_ov(C2->getValue(), Overflow);
1006  if (Overflow)
1007  return Constant::getNullValue(Op0->getType());
1008  }
1009 
1010  // If the operation is with the result of a select instruction, check whether
1011  // operating on either branch of the select always yields the same value.
1012  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1013  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1014  return V;
1015 
1016  // If the operation is with the result of a phi instruction, check whether
1017  // operating on all incoming values of the phi always yields the same value.
1018  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1019  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1020  return V;
1021 
1022  if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned))
1023  return Constant::getNullValue(Op0->getType());
1024 
1025  return nullptr;
1026 }
1027 
1028 /// These are simplifications common to SRem and URem.
1030  const SimplifyQuery &Q, unsigned MaxRecurse) {
1031  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1032  return C;
1033 
1034  if (Value *V = simplifyDivRem(Op0, Op1, false))
1035  return V;
1036 
1037  // (X % Y) % Y -> X % Y
1038  if ((Opcode == Instruction::SRem &&
1039  match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1040  (Opcode == Instruction::URem &&
1041  match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1042  return Op0;
1043 
1044  // (X << Y) % X -> 0
1045  if ((Opcode == Instruction::SRem &&
1046  match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) ||
1047  (Opcode == Instruction::URem &&
1048  match(Op0, m_NUWShl(m_Specific(Op1), m_Value()))))
1049  return Constant::getNullValue(Op0->getType());
1050 
1051  // If the operation is with the result of a select instruction, check whether
1052  // operating on either branch of the select always yields the same value.
1053  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1054  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1055  return V;
1056 
1057  // If the operation is with the result of a phi instruction, check whether
1058  // operating on all incoming values of the phi always yields the same value.
1059  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1060  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1061  return V;
1062 
1063  // If X / Y == 0, then X % Y == X.
1064  if (isDivZero(Op0, Op1, Q, MaxRecurse, Opcode == Instruction::SRem))
1065  return Op0;
1066 
1067  return nullptr;
1068 }
1069 
1070 /// Given operands for an SDiv, see if we can fold the result.
1071 /// If not, this returns null.
1072 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1073  unsigned MaxRecurse) {
1074  return simplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse);
1075 }
1076 
1079 }
1080 
1081 /// Given operands for a UDiv, see if we can fold the result.
1082 /// If not, this returns null.
1083 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1084  unsigned MaxRecurse) {
1085  return simplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse);
1086 }
1087 
1090 }
1091 
1092 /// Given operands for an SRem, see if we can fold the result.
1093 /// If not, this returns null.
1094 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1095  unsigned MaxRecurse) {
1096  return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse);
1097 }
1098 
1101 }
1102 
1103 /// Given operands for a URem, see if we can fold the result.
1104 /// If not, this returns null.
1105 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1106  unsigned MaxRecurse) {
1107  return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse);
1108 }
1109 
1112 }
1113 
1114 /// Returns true if a shift by \c Amount always yields undef.
1115 static bool isUndefShift(Value *Amount) {
1116  Constant *C = dyn_cast<Constant>(Amount);
1117  if (!C)
1118  return false;
1119 
1120  // X shift by undef -> undef because it may shift by the bitwidth.
1121  if (isa<UndefValue>(C))
1122  return true;
1123 
1124  // Shifting by the bitwidth or more is undefined.
1125  if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
1126  if (CI->getValue().getLimitedValue() >=
1127  CI->getType()->getScalarSizeInBits())
1128  return true;
1129 
1130  // If all lanes of a vector shift are undefined the whole shift is.
1131  if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
1132  for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I)
1134  return false;
1135  return true;
1136  }
1137 
1138  return false;
1139 }
1140 
1141 /// Given operands for an Shl, LShr or AShr, see if we can fold the result.
1142 /// If not, this returns null.
1144  Value *Op1, const SimplifyQuery &Q, unsigned MaxRecurse) {
1145  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1146  return C;
1147 
1148  // 0 shift by X -> 0
1149  if (match(Op0, m_Zero()))
1150  return Op0;
1151 
1152  // X shift by 0 -> X
1153  if (match(Op1, m_Zero()))
1154  return Op0;
1155 
1156  // Fold undefined shifts.
1157  if (isUndefShift(Op1))
1158  return UndefValue::get(Op0->getType());
1159 
1160  // If the operation is with the result of a select instruction, check whether
1161  // operating on either branch of the select always yields the same value.
1162  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1163  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1164  return V;
1165 
1166  // If the operation is with the result of a phi instruction, check whether
1167  // operating on all incoming values of the phi always yields the same value.
1168  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1169  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1170  return V;
1171 
1172  // If any bits in the shift amount make that value greater than or equal to
1173  // the number of bits in the type, the shift is undefined.
1174  KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1175  if (Known.One.getLimitedValue() >= Known.getBitWidth())
1176  return UndefValue::get(Op0->getType());
1177 
1178  // If all valid bits in the shift amount are known zero, the first operand is
1179  // unchanged.
1180  unsigned NumValidShiftBits = Log2_32_Ceil(Known.getBitWidth());
1181  if (Known.countMinTrailingZeros() >= NumValidShiftBits)
1182  return Op0;
1183 
1184  return nullptr;
1185 }
1186 
1187 /// \brief Given operands for an Shl, LShr or AShr, see if we can
1188 /// fold the result. If not, this returns null.
1190  Value *Op1, bool isExact, const SimplifyQuery &Q,
1191  unsigned MaxRecurse) {
1192  if (Value *V = SimplifyShift(Opcode, Op0, Op1, Q, MaxRecurse))
1193  return V;
1194 
1195  // X >> X -> 0
1196  if (Op0 == Op1)
1197  return Constant::getNullValue(Op0->getType());
1198 
1199  // undef >> X -> 0
1200  // undef >> X -> undef (if it's exact)
1201  if (match(Op0, m_Undef()))
1202  return isExact ? Op0 : Constant::getNullValue(Op0->getType());
1203 
1204  // The low bit cannot be shifted out of an exact shift if it is set.
1205  if (isExact) {
1206  KnownBits Op0Known = computeKnownBits(Op0, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
1207  if (Op0Known.One[0])
1208  return Op0;
1209  }
1210 
1211  return nullptr;
1212 }
1213 
1214 /// Given operands for an Shl, see if we can fold the result.
1215 /// If not, this returns null.
1216 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1217  const SimplifyQuery &Q, unsigned MaxRecurse) {
1218  if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1219  return V;
1220 
1221  // undef << X -> 0
1222  // undef << X -> undef if (if it's NSW/NUW)
1223  if (match(Op0, m_Undef()))
1224  return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType());
1225 
1226  // (X >> A) << A -> X
1227  Value *X;
1228  if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1229  return X;
1230  return nullptr;
1231 }
1232 
1233 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1234  const SimplifyQuery &Q) {
1235  return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
1236 }
1237 
1238 /// Given operands for an LShr, see if we can fold the result.
1239 /// If not, this returns null.
1240 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1241  const SimplifyQuery &Q, unsigned MaxRecurse) {
1242  if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q,
1243  MaxRecurse))
1244  return V;
1245 
1246  // (X << A) >> A -> X
1247  Value *X;
1248  if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
1249  return X;
1250 
1251  return nullptr;
1252 }
1253 
1254 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1255  const SimplifyQuery &Q) {
1256  return ::SimplifyLShrInst(Op0, Op1, isExact, Q, RecursionLimit);
1257 }
1258 
1259 /// Given operands for an AShr, see if we can fold the result.
1260 /// If not, this returns null.
1261 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1262  const SimplifyQuery &Q, unsigned MaxRecurse) {
1263  if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
1264  MaxRecurse))
1265  return V;
1266 
1267  // all ones >>a X -> -1
1268  // Do not return Op0 because it may contain undef elements if it's a vector.
1269  if (match(Op0, m_AllOnes()))
1270  return Constant::getAllOnesValue(Op0->getType());
1271 
1272  // (X << A) >> A -> X
1273  Value *X;
1274  if (match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
1275  return X;
1276 
1277  // Arithmetic shifting an all-sign-bit value is a no-op.
1278  unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1279  if (NumSignBits == Op0->getType()->getScalarSizeInBits())
1280  return Op0;
1281 
1282  return nullptr;
1283 }
1284 
1285 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1286  const SimplifyQuery &Q) {
1287  return ::SimplifyAShrInst(Op0, Op1, isExact, Q, RecursionLimit);
1288 }
1289 
1290 /// Commuted variants are assumed to be handled by calling this function again
1291 /// with the parameters swapped.
1293  ICmpInst *UnsignedICmp, bool IsAnd) {
1294  Value *X, *Y;
1295 
1296  ICmpInst::Predicate EqPred;
1297  if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) ||
1298  !ICmpInst::isEquality(EqPred))
1299  return nullptr;
1300 
1301  ICmpInst::Predicate UnsignedPred;
1302  if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
1303  ICmpInst::isUnsigned(UnsignedPred))
1304  ;
1305  else if (match(UnsignedICmp,
1306  m_ICmp(UnsignedPred, m_Value(Y), m_Specific(X))) &&
1307  ICmpInst::isUnsigned(UnsignedPred))
1308  UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
1309  else
1310  return nullptr;
1311 
1312  // X < Y && Y != 0 --> X < Y
1313  // X < Y || Y != 0 --> Y != 0
1314  if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE)
1315  return IsAnd ? UnsignedICmp : ZeroICmp;
1316 
1317  // X >= Y || Y != 0 --> true
1318  // X >= Y || Y == 0 --> X >= Y
1319  if (UnsignedPred == ICmpInst::ICMP_UGE && !IsAnd) {
1320  if (EqPred == ICmpInst::ICMP_NE)
1321  return getTrue(UnsignedICmp->getType());
1322  return UnsignedICmp;
1323  }
1324 
1325  // X < Y && Y == 0 --> false
1326  if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
1327  IsAnd)
1328  return getFalse(UnsignedICmp->getType());
1329 
1330  return nullptr;
1331 }
1332 
1333 /// Commuted variants are assumed to be handled by calling this function again
1334 /// with the parameters swapped.
1336  ICmpInst::Predicate Pred0, Pred1;
1337  Value *A ,*B;
1338  if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
1339  !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
1340  return nullptr;
1341 
1342  // We have (icmp Pred0, A, B) & (icmp Pred1, A, B).
1343  // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
1344  // can eliminate Op1 from this 'and'.
1345  if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
1346  return Op0;
1347 
1348  // Check for any combination of predicates that are guaranteed to be disjoint.
1349  if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
1350  (Pred0 == ICmpInst::ICMP_EQ && ICmpInst::isFalseWhenEqual(Pred1)) ||
1351  (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT) ||
1352  (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT))
1353  return getFalse(Op0->getType());
1354 
1355  return nullptr;
1356 }
1357 
1358 /// Commuted variants are assumed to be handled by calling this function again
1359 /// with the parameters swapped.
1361  ICmpInst::Predicate Pred0, Pred1;
1362  Value *A ,*B;
1363  if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
1364  !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
1365  return nullptr;
1366 
1367  // We have (icmp Pred0, A, B) | (icmp Pred1, A, B).
1368  // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
1369  // can eliminate Op0 from this 'or'.
1370  if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
1371  return Op1;
1372 
1373  // Check for any combination of predicates that cover the entire range of
1374  // possibilities.
1375  if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
1376  (Pred0 == ICmpInst::ICMP_NE && ICmpInst::isTrueWhenEqual(Pred1)) ||
1377  (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGE) ||
1378  (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGE))
1379  return getTrue(Op0->getType());
1380 
1381  return nullptr;
1382 }
1383 
1384 /// Test if a pair of compares with a shared operand and 2 constants has an
1385 /// empty set intersection, full set union, or if one compare is a superset of
1386 /// the other.
1388  bool IsAnd) {
1389  // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)).
1390  if (Cmp0->getOperand(0) != Cmp1->getOperand(0))
1391  return nullptr;
1392 
1393  const APInt *C0, *C1;
1394  if (!match(Cmp0->getOperand(1), m_APInt(C0)) ||
1395  !match(Cmp1->getOperand(1), m_APInt(C1)))
1396  return nullptr;
1397 
1398  auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0);
1399  auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1);
1400 
1401  // For and-of-compares, check if the intersection is empty:
1402  // (icmp X, C0) && (icmp X, C1) --> empty set --> false
1403  if (IsAnd && Range0.intersectWith(Range1).isEmptySet())
1404  return getFalse(Cmp0->getType());
1405 
1406  // For or-of-compares, check if the union is full:
1407  // (icmp X, C0) || (icmp X, C1) --> full set --> true
1408  if (!IsAnd && Range0.unionWith(Range1).isFullSet())
1409  return getTrue(Cmp0->getType());
1410 
1411  // Is one range a superset of the other?
1412  // If this is and-of-compares, take the smaller set:
1413  // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42
1414  // If this is or-of-compares, take the larger set:
1415  // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4
1416  if (Range0.contains(Range1))
1417  return IsAnd ? Cmp1 : Cmp0;
1418  if (Range1.contains(Range0))
1419  return IsAnd ? Cmp0 : Cmp1;
1420 
1421  return nullptr;
1422 }
1423 
1425  bool IsAnd) {
1426  ICmpInst::Predicate P0 = Cmp0->getPredicate(), P1 = Cmp1->getPredicate();
1427  if (!match(Cmp0->getOperand(1), m_Zero()) ||
1428  !match(Cmp1->getOperand(1), m_Zero()) || P0 != P1)
1429  return nullptr;
1430 
1431  if ((IsAnd && P0 != ICmpInst::ICMP_NE) || (!IsAnd && P1 != ICmpInst::ICMP_EQ))
1432  return nullptr;
1433 
1434  // We have either "(X == 0 || Y == 0)" or "(X != 0 && Y != 0)".
1435  Value *X = Cmp0->getOperand(0);
1436  Value *Y = Cmp1->getOperand(0);
1437 
1438  // If one of the compares is a masked version of a (not) null check, then
1439  // that compare implies the other, so we eliminate the other. Optionally, look
1440  // through a pointer-to-int cast to match a null check of a pointer type.
1441 
1442  // (X == 0) || (([ptrtoint] X & ?) == 0) --> ([ptrtoint] X & ?) == 0
1443  // (X == 0) || ((? & [ptrtoint] X) == 0) --> (? & [ptrtoint] X) == 0
1444  // (X != 0) && (([ptrtoint] X & ?) != 0) --> ([ptrtoint] X & ?) != 0
1445  // (X != 0) && ((? & [ptrtoint] X) != 0) --> (? & [ptrtoint] X) != 0
1446  if (match(Y, m_c_And(m_Specific(X), m_Value())) ||
1448  return Cmp1;
1449 
1450  // (([ptrtoint] Y & ?) == 0) || (Y == 0) --> ([ptrtoint] Y & ?) == 0
1451  // ((? & [ptrtoint] Y) == 0) || (Y == 0) --> (? & [ptrtoint] Y) == 0
1452  // (([ptrtoint] Y & ?) != 0) && (Y != 0) --> ([ptrtoint] Y & ?) != 0
1453  // ((? & [ptrtoint] Y) != 0) && (Y != 0) --> (? & [ptrtoint] Y) != 0
1454  if (match(X, m_c_And(m_Specific(Y), m_Value())) ||
1456  return Cmp0;
1457 
1458  return nullptr;
1459 }
1460 
1462  // (icmp (add V, C0), C1) & (icmp V, C0)
1463  ICmpInst::Predicate Pred0, Pred1;
1464  const APInt *C0, *C1;
1465  Value *V;
1466  if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1467  return nullptr;
1468 
1469  if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1470  return nullptr;
1471 
1472  auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1473  if (AddInst->getOperand(1) != Op1->getOperand(1))
1474  return nullptr;
1475 
1476  Type *ITy = Op0->getType();
1477  bool isNSW = AddInst->hasNoSignedWrap();
1478  bool isNUW = AddInst->hasNoUnsignedWrap();
1479 
1480  const APInt Delta = *C1 - *C0;
1481  if (C0->isStrictlyPositive()) {
1482  if (Delta == 2) {
1483  if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
1484  return getFalse(ITy);
1485  if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1486  return getFalse(ITy);
1487  }
1488  if (Delta == 1) {
1489  if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
1490  return getFalse(ITy);
1491  if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1492  return getFalse(ITy);
1493  }
1494  }
1495  if (C0->getBoolValue() && isNUW) {
1496  if (Delta == 2)
1497  if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
1498  return getFalse(ITy);
1499  if (Delta == 1)
1500  if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
1501  return getFalse(ITy);
1502  }
1503 
1504  return nullptr;
1505 }
1506 
1508  if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true))
1509  return X;
1510  if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true))
1511  return X;
1512 
1513  if (Value *X = simplifyAndOfICmpsWithSameOperands(Op0, Op1))
1514  return X;
1515  if (Value *X = simplifyAndOfICmpsWithSameOperands(Op1, Op0))
1516  return X;
1517 
1518  if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true))
1519  return X;
1520 
1521  if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, true))
1522  return X;
1523 
1524  if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1))
1525  return X;
1526  if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0))
1527  return X;
1528 
1529  return nullptr;
1530 }
1531 
1533  // (icmp (add V, C0), C1) | (icmp V, C0)
1534  ICmpInst::Predicate Pred0, Pred1;
1535  const APInt *C0, *C1;
1536  Value *V;
1537  if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1538  return nullptr;
1539 
1540  if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1541  return nullptr;
1542 
1543  auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1544  if (AddInst->getOperand(1) != Op1->getOperand(1))
1545  return nullptr;
1546 
1547  Type *ITy = Op0->getType();
1548  bool isNSW = AddInst->hasNoSignedWrap();
1549  bool isNUW = AddInst->hasNoUnsignedWrap();
1550 
1551  const APInt Delta = *C1 - *C0;
1552  if (C0->isStrictlyPositive()) {
1553  if (Delta == 2) {
1554  if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
1555  return getTrue(ITy);
1556  if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1557  return getTrue(ITy);
1558  }
1559  if (Delta == 1) {
1560  if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
1561  return getTrue(ITy);
1562  if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1563  return getTrue(ITy);
1564  }
1565  }
1566  if (C0->getBoolValue() && isNUW) {
1567  if (Delta == 2)
1568  if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
1569  return getTrue(ITy);
1570  if (Delta == 1)
1571  if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
1572  return getTrue(ITy);
1573  }
1574 
1575  return nullptr;
1576 }
1577 
1579  if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false))
1580  return X;
1581  if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false))
1582  return X;
1583 
1584  if (Value *X = simplifyOrOfICmpsWithSameOperands(Op0, Op1))
1585  return X;
1586  if (Value *X = simplifyOrOfICmpsWithSameOperands(Op1, Op0))
1587  return X;
1588 
1589  if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false))
1590  return X;
1591 
1592  if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, false))
1593  return X;
1594 
1595  if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1))
1596  return X;
1597  if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0))
1598  return X;
1599 
1600  return nullptr;
1601 }
1602 
1603 static Value *simplifyAndOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
1604  Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
1605  Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
1606  if (LHS0->getType() != RHS0->getType())
1607  return nullptr;
1608 
1609  FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
1610  if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) ||
1611  (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) {
1612  // (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y
1613  // (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X
1614  // (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y
1615  // (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X
1616  // (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y
1617  // (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X
1618  // (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y
1619  // (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X
1620  if ((isKnownNeverNaN(LHS0) && (LHS1 == RHS0 || LHS1 == RHS1)) ||
1621  (isKnownNeverNaN(LHS1) && (LHS0 == RHS0 || LHS0 == RHS1)))
1622  return RHS;
1623 
1624  // (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y
1625  // (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X
1626  // (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y
1627  // (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X
1628  // (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y
1629  // (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X
1630  // (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y
1631  // (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X
1632  if ((isKnownNeverNaN(RHS0) && (RHS1 == LHS0 || RHS1 == LHS1)) ||
1633  (isKnownNeverNaN(RHS1) && (RHS0 == LHS0 || RHS0 == LHS1)))
1634  return LHS;
1635  }
1636 
1637  return nullptr;
1638 }
1639 
1640 static Value *simplifyAndOrOfCmps(Value *Op0, Value *Op1, bool IsAnd) {
1641  // Look through casts of the 'and' operands to find compares.
1642  auto *Cast0 = dyn_cast<CastInst>(Op0);
1643  auto *Cast1 = dyn_cast<CastInst>(Op1);
1644  if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() &&
1645  Cast0->getSrcTy() == Cast1->getSrcTy()) {
1646  Op0 = Cast0->getOperand(0);
1647  Op1 = Cast1->getOperand(0);
1648  }
1649 
1650  Value *V = nullptr;
1651  auto *ICmp0 = dyn_cast<ICmpInst>(Op0);
1652  auto *ICmp1 = dyn_cast<ICmpInst>(Op1);
1653  if (ICmp0 && ICmp1)
1654  V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1) :
1655  simplifyOrOfICmps(ICmp0, ICmp1);
1656 
1657  auto *FCmp0 = dyn_cast<FCmpInst>(Op0);
1658  auto *FCmp1 = dyn_cast<FCmpInst>(Op1);
1659  if (FCmp0 && FCmp1)
1660  V = simplifyAndOrOfFCmps(FCmp0, FCmp1, IsAnd);
1661 
1662  if (!V)
1663  return nullptr;
1664  if (!Cast0)
1665  return V;
1666 
1667  // If we looked through casts, we can only handle a constant simplification
1668  // because we are not allowed to create a cast instruction here.
1669  if (auto *C = dyn_cast<Constant>(V))
1670  return ConstantExpr::getCast(Cast0->getOpcode(), C, Cast0->getType());
1671 
1672  return nullptr;
1673 }
1674 
1675 /// Given operands for an And, see if we can fold the result.
1676 /// If not, this returns null.
1677 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1678  unsigned MaxRecurse) {
1679  if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q))
1680  return C;
1681 
1682  // X & undef -> 0
1683  if (match(Op1, m_Undef()))
1684  return Constant::getNullValue(Op0->getType());
1685 
1686  // X & X = X
1687  if (Op0 == Op1)
1688  return Op0;
1689 
1690  // X & 0 = 0
1691  if (match(Op1, m_Zero()))
1692  return Op1;
1693 
1694  // X & -1 = X
1695  if (match(Op1, m_AllOnes()))
1696  return Op0;
1697 
1698  // A & ~A = ~A & A = 0
1699  if (match(Op0, m_Not(m_Specific(Op1))) ||
1700  match(Op1, m_Not(m_Specific(Op0))))
1701  return Constant::getNullValue(Op0->getType());
1702 
1703  // (A | ?) & A = A
1704  if (match(Op0, m_c_Or(m_Specific(Op1), m_Value())))
1705  return Op1;
1706 
1707  // A & (A | ?) = A
1708  if (match(Op1, m_c_Or(m_Specific(Op0), m_Value())))
1709  return Op0;
1710 
1711  // A mask that only clears known zeros of a shifted value is a no-op.
1712  Value *X;
1713  const APInt *Mask;
1714  const APInt *ShAmt;
1715  if (match(Op1, m_APInt(Mask))) {
1716  // If all bits in the inverted and shifted mask are clear:
1717  // and (shl X, ShAmt), Mask --> shl X, ShAmt
1718  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) &&
1719  (~(*Mask)).lshr(*ShAmt).isNullValue())
1720  return Op0;
1721 
1722  // If all bits in the inverted and shifted mask are clear:
1723  // and (lshr X, ShAmt), Mask --> lshr X, ShAmt
1724  if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) &&
1725  (~(*Mask)).shl(*ShAmt).isNullValue())
1726  return Op0;
1727  }
1728 
1729  // A & (-A) = A if A is a power of two or zero.
1730  if (match(Op0, m_Neg(m_Specific(Op1))) ||
1731  match(Op1, m_Neg(m_Specific(Op0)))) {
1732  if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1733  Q.DT))
1734  return Op0;
1735  if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1736  Q.DT))
1737  return Op1;
1738  }
1739 
1740  if (Value *V = simplifyAndOrOfCmps(Op0, Op1, true))
1741  return V;
1742 
1743  // Try some generic simplifications for associative operations.
1744  if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1745  MaxRecurse))
1746  return V;
1747 
1748  // And distributes over Or. Try some generic simplifications based on this.
1749  if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1750  Q, MaxRecurse))
1751  return V;
1752 
1753  // And distributes over Xor. Try some generic simplifications based on this.
1754  if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1755  Q, MaxRecurse))
1756  return V;
1757 
1758  // If the operation is with the result of a select instruction, check whether
1759  // operating on either branch of the select always yields the same value.
1760  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1761  if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1762  MaxRecurse))
1763  return V;
1764 
1765  // If the operation is with the result of a phi instruction, check whether
1766  // operating on all incoming values of the phi always yields the same value.
1767  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1768  if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1769  MaxRecurse))
1770  return V;
1771 
1772  return nullptr;
1773 }
1774 
1777 }
1778 
1779 /// Given operands for an Or, see if we can fold the result.
1780 /// If not, this returns null.
1781 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1782  unsigned MaxRecurse) {
1783  if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q))
1784  return C;
1785 
1786  // X | undef -> -1
1787  // X | -1 = -1
1788  // Do not return Op1 because it may contain undef elements if it's a vector.
1789  if (match(Op1, m_Undef()) || match(Op1, m_AllOnes()))
1790  return Constant::getAllOnesValue(Op0->getType());
1791 
1792  // X | X = X
1793  // X | 0 = X
1794  if (Op0 == Op1 || match(Op1, m_Zero()))
1795  return Op0;
1796 
1797  // A | ~A = ~A | A = -1
1798  if (match(Op0, m_Not(m_Specific(Op1))) ||
1799  match(Op1, m_Not(m_Specific(Op0))))
1800  return Constant::getAllOnesValue(Op0->getType());
1801 
1802  // (A & ?) | A = A
1803  if (match(Op0, m_c_And(m_Specific(Op1), m_Value())))
1804  return Op1;
1805 
1806  // A | (A & ?) = A
1807  if (match(Op1, m_c_And(m_Specific(Op0), m_Value())))
1808  return Op0;
1809 
1810  // ~(A & ?) | A = -1
1811  if (match(Op0, m_Not(m_c_And(m_Specific(Op1), m_Value()))))
1812  return Constant::getAllOnesValue(Op1->getType());
1813 
1814  // A | ~(A & ?) = -1
1815  if (match(Op1, m_Not(m_c_And(m_Specific(Op1), m_Value()))))
1816  return Constant::getAllOnesValue(Op0->getType());
1817 
1818  Value *A, *B;
1819  // (A & ~B) | (A ^ B) -> (A ^ B)
1820  // (~B & A) | (A ^ B) -> (A ^ B)
1821  // (A & ~B) | (B ^ A) -> (B ^ A)
1822  // (~B & A) | (B ^ A) -> (B ^ A)
1823  if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
1824  (match(Op0, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
1825  match(Op0, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
1826  return Op1;
1827 
1828  // Commute the 'or' operands.
1829  // (A ^ B) | (A & ~B) -> (A ^ B)
1830  // (A ^ B) | (~B & A) -> (A ^ B)
1831  // (B ^ A) | (A & ~B) -> (B ^ A)
1832  // (B ^ A) | (~B & A) -> (B ^ A)
1833  if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
1834  (match(Op1, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
1835  match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
1836  return Op0;
1837 
1838  // (A & B) | (~A ^ B) -> (~A ^ B)
1839  // (B & A) | (~A ^ B) -> (~A ^ B)
1840  // (A & B) | (B ^ ~A) -> (B ^ ~A)
1841  // (B & A) | (B ^ ~A) -> (B ^ ~A)
1842  if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1843  (match(Op1, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
1844  match(Op1, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
1845  return Op1;
1846 
1847  // (~A ^ B) | (A & B) -> (~A ^ B)
1848  // (~A ^ B) | (B & A) -> (~A ^ B)
1849  // (B ^ ~A) | (A & B) -> (B ^ ~A)
1850  // (B ^ ~A) | (B & A) -> (B ^ ~A)
1851  if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1852  (match(Op0, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
1853  match(Op0, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
1854  return Op0;
1855 
1856  if (Value *V = simplifyAndOrOfCmps(Op0, Op1, false))
1857  return V;
1858 
1859  // Try some generic simplifications for associative operations.
1860  if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1861  MaxRecurse))
1862  return V;
1863 
1864  // Or distributes over And. Try some generic simplifications based on this.
1865  if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1866  MaxRecurse))
1867  return V;
1868 
1869  // If the operation is with the result of a select instruction, check whether
1870  // operating on either branch of the select always yields the same value.
1871  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1872  if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1873  MaxRecurse))
1874  return V;
1875 
1876  // (A & C1)|(B & C2)
1877  const APInt *C1, *C2;
1878  if (match(Op0, m_And(m_Value(A), m_APInt(C1))) &&
1879  match(Op1, m_And(m_Value(B), m_APInt(C2)))) {
1880  if (*C1 == ~*C2) {
1881  // (A & C1)|(B & C2)
1882  // If we have: ((V + N) & C1) | (V & C2)
1883  // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1884  // replace with V+N.
1885  Value *N;
1886  if (C2->isMask() && // C2 == 0+1+
1887  match(A, m_c_Add(m_Specific(B), m_Value(N)))) {
1888  // Add commutes, try both ways.
1889  if (MaskedValueIsZero(N, *C2, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1890  return A;
1891  }
1892  // Or commutes, try both ways.
1893  if (C1->isMask() &&
1894  match(B, m_c_Add(m_Specific(A), m_Value(N)))) {
1895  // Add commutes, try both ways.
1896  if (MaskedValueIsZero(N, *C1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1897  return B;
1898  }
1899  }
1900  }
1901 
1902  // If the operation is with the result of a phi instruction, check whether
1903  // operating on all incoming values of the phi always yields the same value.
1904  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1905  if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1906  return V;
1907 
1908  return nullptr;
1909 }
1910 
1913 }
1914 
1915 /// Given operands for a Xor, see if we can fold the result.
1916 /// If not, this returns null.
1917 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1918  unsigned MaxRecurse) {
1919  if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q))
1920  return C;
1921 
1922  // A ^ undef -> undef
1923  if (match(Op1, m_Undef()))
1924  return Op1;
1925 
1926  // A ^ 0 = A
1927  if (match(Op1, m_Zero()))
1928  return Op0;
1929 
1930  // A ^ A = 0
1931  if (Op0 == Op1)
1932  return Constant::getNullValue(Op0->getType());
1933 
1934  // A ^ ~A = ~A ^ A = -1
1935  if (match(Op0, m_Not(m_Specific(Op1))) ||
1936  match(Op1, m_Not(m_Specific(Op0))))
1937  return Constant::getAllOnesValue(Op0->getType());
1938 
1939  // Try some generic simplifications for associative operations.
1940  if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1941  MaxRecurse))
1942  return V;
1943 
1944  // Threading Xor over selects and phi nodes is pointless, so don't bother.
1945  // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1946  // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1947  // only if B and C are equal. If B and C are equal then (since we assume
1948  // that operands have already been simplified) "select(cond, B, C)" should
1949  // have been simplified to the common value of B and C already. Analysing
1950  // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1951  // for threading over phi nodes.
1952 
1953  return nullptr;
1954 }
1955 
1958 }
1959 
1960 
1962  return CmpInst::makeCmpResultType(Op->getType());
1963 }
1964 
1965 /// Rummage around inside V looking for something equivalent to the comparison
1966 /// "LHS Pred RHS". Return such a value if found, otherwise return null.
1967 /// Helper function for analyzing max/min idioms.
1969  Value *LHS, Value *RHS) {
1971  if (!SI)
1972  return nullptr;
1973  CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1974  if (!Cmp)
1975  return nullptr;
1976  Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1977  if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1978  return Cmp;
1979  if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1980  LHS == CmpRHS && RHS == CmpLHS)
1981  return Cmp;
1982  return nullptr;
1983 }
1984 
1985 // A significant optimization not implemented here is assuming that alloca
1986 // addresses are not equal to incoming argument values. They don't *alias*,
1987 // as we say, but that doesn't mean they aren't equal, so we take a
1988 // conservative approach.
1989 //
1990 // This is inspired in part by C++11 5.10p1:
1991 // "Two pointers of the same type compare equal if and only if they are both
1992 // null, both point to the same function, or both represent the same
1993 // address."
1994 //
1995 // This is pretty permissive.
1996 //
1997 // It's also partly due to C11 6.5.9p6:
1998 // "Two pointers compare equal if and only if both are null pointers, both are
1999 // pointers to the same object (including a pointer to an object and a
2000 // subobject at its beginning) or function, both are pointers to one past the
2001 // last element of the same array object, or one is a pointer to one past the
2002 // end of one array object and the other is a pointer to the start of a
2003 // different array object that happens to immediately follow the first array
2004 // object in the address space.)
2005 //
2006 // C11's version is more restrictive, however there's no reason why an argument
2007 // couldn't be a one-past-the-end value for a stack object in the caller and be
2008 // equal to the beginning of a stack object in the callee.
2009 //
2010 // If the C and C++ standards are ever made sufficiently restrictive in this
2011 // area, it may be possible to update LLVM's semantics accordingly and reinstate
2012 // this optimization.
2013 static Constant *
2015  const DominatorTree *DT, CmpInst::Predicate Pred,
2016  AssumptionCache *AC, const Instruction *CxtI,
2017  Value *LHS, Value *RHS) {
2018  // First, skip past any trivial no-ops.
2019  LHS = LHS->stripPointerCasts();
2020  RHS = RHS->stripPointerCasts();
2021 
2022  // A non-null pointer is not equal to a null pointer.
2023  if (llvm::isKnownNonZero(LHS, DL) && isa<ConstantPointerNull>(RHS) &&
2024  (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE))
2025  return ConstantInt::get(GetCompareTy(LHS),
2026  !CmpInst::isTrueWhenEqual(Pred));
2027 
2028  // We can only fold certain predicates on pointer comparisons.
2029  switch (Pred) {
2030  default:
2031  return nullptr;
2032 
2033  // Equality comaprisons are easy to fold.
2034  case CmpInst::ICMP_EQ:
2035  case CmpInst::ICMP_NE:
2036  break;
2037 
2038  // We can only handle unsigned relational comparisons because 'inbounds' on
2039  // a GEP only protects against unsigned wrapping.
2040  case CmpInst::ICMP_UGT:
2041  case CmpInst::ICMP_UGE:
2042  case CmpInst::ICMP_ULT:
2043  case CmpInst::ICMP_ULE:
2044  // However, we have to switch them to their signed variants to handle
2045  // negative indices from the base pointer.
2046  Pred = ICmpInst::getSignedPredicate(Pred);
2047  break;
2048  }
2049 
2050  // Strip off any constant offsets so that we can reason about them.
2051  // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
2052  // here and compare base addresses like AliasAnalysis does, however there are
2053  // numerous hazards. AliasAnalysis and its utilities rely on special rules
2054  // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
2055  // doesn't need to guarantee pointer inequality when it says NoAlias.
2056  Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
2057  Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
2058 
2059  // If LHS and RHS are related via constant offsets to the same base
2060  // value, we can replace it with an icmp which just compares the offsets.
2061  if (LHS == RHS)
2062  return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
2063 
2064  // Various optimizations for (in)equality comparisons.
2065  if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
2066  // Different non-empty allocations that exist at the same time have
2067  // different addresses (if the program can tell). Global variables always
2068  // exist, so they always exist during the lifetime of each other and all
2069  // allocas. Two different allocas usually have different addresses...
2070  //
2071  // However, if there's an @llvm.stackrestore dynamically in between two
2072  // allocas, they may have the same address. It's tempting to reduce the
2073  // scope of the problem by only looking at *static* allocas here. That would
2074  // cover the majority of allocas while significantly reducing the likelihood
2075  // of having an @llvm.stackrestore pop up in the middle. However, it's not
2076  // actually impossible for an @llvm.stackrestore to pop up in the middle of
2077  // an entry block. Also, if we have a block that's not attached to a
2078  // function, we can't tell if it's "static" under the current definition.
2079  // Theoretically, this problem could be fixed by creating a new kind of
2080  // instruction kind specifically for static allocas. Such a new instruction
2081  // could be required to be at the top of the entry block, thus preventing it
2082  // from being subject to a @llvm.stackrestore. Instcombine could even
2083  // convert regular allocas into these special allocas. It'd be nifty.
2084  // However, until then, this problem remains open.
2085  //
2086  // So, we'll assume that two non-empty allocas have different addresses
2087  // for now.
2088  //
2089  // With all that, if the offsets are within the bounds of their allocations
2090  // (and not one-past-the-end! so we can't use inbounds!), and their
2091  // allocations aren't the same, the pointers are not equal.
2092  //
2093  // Note that it's not necessary to check for LHS being a global variable
2094  // address, due to canonicalization and constant folding.
2095  if (isa<AllocaInst>(LHS) &&
2096  (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
2097  ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
2098  ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
2099  uint64_t LHSSize, RHSSize;
2100  if (LHSOffsetCI && RHSOffsetCI &&
2101  getObjectSize(LHS, LHSSize, DL, TLI) &&
2102  getObjectSize(RHS, RHSSize, DL, TLI)) {
2103  const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
2104  const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
2105  if (!LHSOffsetValue.isNegative() &&
2106  !RHSOffsetValue.isNegative() &&
2107  LHSOffsetValue.ult(LHSSize) &&
2108  RHSOffsetValue.ult(RHSSize)) {
2109  return ConstantInt::get(GetCompareTy(LHS),
2110  !CmpInst::isTrueWhenEqual(Pred));
2111  }
2112  }
2113 
2114  // Repeat the above check but this time without depending on DataLayout
2115  // or being able to compute a precise size.
2116  if (!cast<PointerType>(LHS->getType())->isEmptyTy() &&
2117  !cast<PointerType>(RHS->getType())->isEmptyTy() &&
2118  LHSOffset->isNullValue() &&
2119  RHSOffset->isNullValue())
2120  return ConstantInt::get(GetCompareTy(LHS),
2121  !CmpInst::isTrueWhenEqual(Pred));
2122  }
2123 
2124  // Even if an non-inbounds GEP occurs along the path we can still optimize
2125  // equality comparisons concerning the result. We avoid walking the whole
2126  // chain again by starting where the last calls to
2127  // stripAndComputeConstantOffsets left off and accumulate the offsets.
2128  Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true);
2129  Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true);
2130  if (LHS == RHS)
2131  return ConstantExpr::getICmp(Pred,
2132  ConstantExpr::getAdd(LHSOffset, LHSNoBound),
2133  ConstantExpr::getAdd(RHSOffset, RHSNoBound));
2134 
2135  // If one side of the equality comparison must come from a noalias call
2136  // (meaning a system memory allocation function), and the other side must
2137  // come from a pointer that cannot overlap with dynamically-allocated
2138  // memory within the lifetime of the current function (allocas, byval
2139  // arguments, globals), then determine the comparison result here.
2140  SmallVector<Value *, 8> LHSUObjs, RHSUObjs;
2141  GetUnderlyingObjects(LHS, LHSUObjs, DL);
2142  GetUnderlyingObjects(RHS, RHSUObjs, DL);
2143 
2144  // Is the set of underlying objects all noalias calls?
2145  auto IsNAC = [](ArrayRef<Value *> Objects) {
2146  return all_of(Objects, isNoAliasCall);
2147  };
2148 
2149  // Is the set of underlying objects all things which must be disjoint from
2150  // noalias calls. For allocas, we consider only static ones (dynamic
2151  // allocas might be transformed into calls to malloc not simultaneously
2152  // live with the compared-to allocation). For globals, we exclude symbols
2153  // that might be resolve lazily to symbols in another dynamically-loaded
2154  // library (and, thus, could be malloc'ed by the implementation).
2155  auto IsAllocDisjoint = [](ArrayRef<Value *> Objects) {
2156  return all_of(Objects, [](Value *V) {
2157  if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
2158  return AI->getParent() && AI->getFunction() && AI->isStaticAlloca();
2159  if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
2160  return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() ||
2161  GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) &&
2162  !GV->isThreadLocal();
2163  if (const Argument *A = dyn_cast<Argument>(V))
2164  return A->hasByValAttr();
2165  return false;
2166  });
2167  };
2168 
2169  if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
2170  (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
2171  return ConstantInt::get(GetCompareTy(LHS),
2172  !CmpInst::isTrueWhenEqual(Pred));
2173 
2174  // Fold comparisons for non-escaping pointer even if the allocation call
2175  // cannot be elided. We cannot fold malloc comparison to null. Also, the
2176  // dynamic allocation call could be either of the operands.
2177  Value *MI = nullptr;
2178  if (isAllocLikeFn(LHS, TLI) &&
2179  llvm::isKnownNonZero(RHS, DL, 0, nullptr, CxtI, DT))
2180  MI = LHS;
2181  else if (isAllocLikeFn(RHS, TLI) &&
2182  llvm::isKnownNonZero(LHS, DL, 0, nullptr, CxtI, DT))
2183  MI = RHS;
2184  // FIXME: We should also fold the compare when the pointer escapes, but the
2185  // compare dominates the pointer escape
2186  if (MI && !PointerMayBeCaptured(MI, true, true))
2187  return ConstantInt::get(GetCompareTy(LHS),
2189  }
2190 
2191  // Otherwise, fail.
2192  return nullptr;
2193 }
2194 
2195 /// Fold an icmp when its operands have i1 scalar type.
2197  Value *RHS, const SimplifyQuery &Q) {
2198  Type *ITy = GetCompareTy(LHS); // The return type.
2199  Type *OpTy = LHS->getType(); // The operand type.
2200  if (!OpTy->isIntOrIntVectorTy(1))
2201  return nullptr;
2202 
2203  // A boolean compared to true/false can be simplified in 14 out of the 20
2204  // (10 predicates * 2 constants) possible combinations. Cases not handled here
2205  // require a 'not' of the LHS, so those must be transformed in InstCombine.
2206  if (match(RHS, m_Zero())) {
2207  switch (Pred) {
2208  case CmpInst::ICMP_NE: // X != 0 -> X
2209  case CmpInst::ICMP_UGT: // X >u 0 -> X
2210  case CmpInst::ICMP_SLT: // X <s 0 -> X
2211  return LHS;
2212 
2213  case CmpInst::ICMP_ULT: // X <u 0 -> false
2214  case CmpInst::ICMP_SGT: // X >s 0 -> false
2215  return getFalse(ITy);
2216 
2217  case CmpInst::ICMP_UGE: // X >=u 0 -> true
2218  case CmpInst::ICMP_SLE: // X <=s 0 -> true
2219  return getTrue(ITy);
2220 
2221  default: break;
2222  }
2223  } else if (match(RHS, m_One())) {
2224  switch (Pred) {
2225  case CmpInst::ICMP_EQ: // X == 1 -> X
2226  case CmpInst::ICMP_UGE: // X >=u 1 -> X
2227  case CmpInst::ICMP_SLE: // X <=s -1 -> X
2228  return LHS;
2229 
2230  case CmpInst::ICMP_UGT: // X >u 1 -> false
2231  case CmpInst::ICMP_SLT: // X <s -1 -> false
2232  return getFalse(ITy);
2233 
2234  case CmpInst::ICMP_ULE: // X <=u 1 -> true
2235  case CmpInst::ICMP_SGE: // X >=s -1 -> true
2236  return getTrue(ITy);
2237 
2238  default: break;
2239  }
2240  }
2241 
2242  switch (Pred) {
2243  default:
2244  break;
2245  case ICmpInst::ICMP_UGE:
2246  if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
2247  return getTrue(ITy);
2248  break;
2249  case ICmpInst::ICMP_SGE:
2250  /// For signed comparison, the values for an i1 are 0 and -1
2251  /// respectively. This maps into a truth table of:
2252  /// LHS | RHS | LHS >=s RHS | LHS implies RHS
2253  /// 0 | 0 | 1 (0 >= 0) | 1
2254  /// 0 | 1 | 1 (0 >= -1) | 1
2255  /// 1 | 0 | 0 (-1 >= 0) | 0
2256  /// 1 | 1 | 1 (-1 >= -1) | 1
2257  if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
2258  return getTrue(ITy);
2259  break;
2260  case ICmpInst::ICMP_ULE:
2261  if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
2262  return getTrue(ITy);
2263  break;
2264  }
2265 
2266  return nullptr;
2267 }
2268 
2269 /// Try hard to fold icmp with zero RHS because this is a common case.
2271  Value *RHS, const SimplifyQuery &Q) {
2272  if (!match(RHS, m_Zero()))
2273  return nullptr;
2274 
2275  Type *ITy = GetCompareTy(LHS); // The return type.
2276  switch (Pred) {
2277  default:
2278  llvm_unreachable("Unknown ICmp predicate!");
2279  case ICmpInst::ICMP_ULT:
2280  return getFalse(ITy);
2281  case ICmpInst::ICMP_UGE:
2282  return getTrue(ITy);
2283  case ICmpInst::ICMP_EQ:
2284  case ICmpInst::ICMP_ULE:
2285  if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2286  return getFalse(ITy);
2287  break;
2288  case ICmpInst::ICMP_NE:
2289  case ICmpInst::ICMP_UGT:
2290  if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2291  return getTrue(ITy);
2292  break;
2293  case ICmpInst::ICMP_SLT: {
2294  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2295  if (LHSKnown.isNegative())
2296  return getTrue(ITy);
2297  if (LHSKnown.isNonNegative())
2298  return getFalse(ITy);
2299  break;
2300  }
2301  case ICmpInst::ICMP_SLE: {
2302  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2303  if (LHSKnown.isNegative())
2304  return getTrue(ITy);
2305  if (LHSKnown.isNonNegative() &&
2306  isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2307  return getFalse(ITy);
2308  break;
2309  }
2310  case ICmpInst::ICMP_SGE: {
2311  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2312  if (LHSKnown.isNegative())
2313  return getFalse(ITy);
2314  if (LHSKnown.isNonNegative())
2315  return getTrue(ITy);
2316  break;
2317  }
2318  case ICmpInst::ICMP_SGT: {
2319  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2320  if (LHSKnown.isNegative())
2321  return getFalse(ITy);
2322  if (LHSKnown.isNonNegative() &&
2323  isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2324  return getTrue(ITy);
2325  break;
2326  }
2327  }
2328 
2329  return nullptr;
2330 }
2331 
2332 /// Many binary operators with a constant operand have an easy-to-compute
2333 /// range of outputs. This can be used to fold a comparison to always true or
2334 /// always false.
2335 static void setLimitsForBinOp(BinaryOperator &BO, APInt &Lower, APInt &Upper) {
2336  unsigned Width = Lower.getBitWidth();
2337  const APInt *C;
2338  switch (BO.getOpcode()) {
2339  case Instruction::Add:
2340  if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) {
2341  // FIXME: If we have both nuw and nsw, we should reduce the range further.
2342  if (BO.hasNoUnsignedWrap()) {
2343  // 'add nuw x, C' produces [C, UINT_MAX].
2344  Lower = *C;
2345  } else if (BO.hasNoSignedWrap()) {
2346  if (C->isNegative()) {
2347  // 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C].
2348  Lower = APInt::getSignedMinValue(Width);
2349  Upper = APInt::getSignedMaxValue(Width) + *C + 1;
2350  } else {
2351  // 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX].
2352  Lower = APInt::getSignedMinValue(Width) + *C;
2353  Upper = APInt::getSignedMaxValue(Width) + 1;
2354  }
2355  }
2356  }
2357  break;
2358 
2359  case Instruction::And:
2360  if (match(BO.getOperand(1), m_APInt(C)))
2361  // 'and x, C' produces [0, C].
2362  Upper = *C + 1;
2363  break;
2364 
2365  case Instruction::Or:
2366  if (match(BO.getOperand(1), m_APInt(C)))
2367  // 'or x, C' produces [C, UINT_MAX].
2368  Lower = *C;
2369  break;
2370 
2371  case Instruction::AShr:
2372  if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) {
2373  // 'ashr x, C' produces [INT_MIN >> C, INT_MAX >> C].
2374  Lower = APInt::getSignedMinValue(Width).ashr(*C);
2375  Upper = APInt::getSignedMaxValue(Width).ashr(*C) + 1;
2376  } else if (match(BO.getOperand(0), m_APInt(C))) {
2377  unsigned ShiftAmount = Width - 1;
2378  if (!C->isNullValue() && BO.isExact())
2379  ShiftAmount = C->countTrailingZeros();
2380  if (C->isNegative()) {
2381  // 'ashr C, x' produces [C, C >> (Width-1)]
2382  Lower = *C;
2383  Upper = C->ashr(ShiftAmount) + 1;
2384  } else {
2385  // 'ashr C, x' produces [C >> (Width-1), C]
2386  Lower = C->ashr(ShiftAmount);
2387  Upper = *C + 1;
2388  }
2389  }
2390  break;
2391 
2392  case Instruction::LShr:
2393  if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) {
2394  // 'lshr x, C' produces [0, UINT_MAX >> C].
2395  Upper = APInt::getAllOnesValue(Width).lshr(*C) + 1;
2396  } else if (match(BO.getOperand(0), m_APInt(C))) {
2397  // 'lshr C, x' produces [C >> (Width-1), C].
2398  unsigned ShiftAmount = Width - 1;
2399  if (!C->isNullValue() && BO.isExact())
2400  ShiftAmount = C->countTrailingZeros();
2401  Lower = C->lshr(ShiftAmount);
2402  Upper = *C + 1;
2403  }
2404  break;
2405 
2406  case Instruction::Shl:
2407  if (match(BO.getOperand(0), m_APInt(C))) {
2408  if (BO.hasNoUnsignedWrap()) {
2409  // 'shl nuw C, x' produces [C, C << CLZ(C)]
2410  Lower = *C;
2411  Upper = Lower.shl(Lower.countLeadingZeros()) + 1;
2412  } else if (BO.hasNoSignedWrap()) { // TODO: What if both nuw+nsw?
2413  if (C->isNegative()) {
2414  // 'shl nsw C, x' produces [C << CLO(C)-1, C]
2415  unsigned ShiftAmount = C->countLeadingOnes() - 1;
2416  Lower = C->shl(ShiftAmount);
2417  Upper = *C + 1;
2418  } else {
2419  // 'shl nsw C, x' produces [C, C << CLZ(C)-1]
2420  unsigned ShiftAmount = C->countLeadingZeros() - 1;
2421  Lower = *C;
2422  Upper = C->shl(ShiftAmount) + 1;
2423  }
2424  }
2425  }
2426  break;
2427 
2428  case Instruction::SDiv:
2429  if (match(BO.getOperand(1), m_APInt(C))) {
2430  APInt IntMin = APInt::getSignedMinValue(Width);
2431  APInt IntMax = APInt::getSignedMaxValue(Width);
2432  if (C->isAllOnesValue()) {
2433  // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
2434  // where C != -1 and C != 0 and C != 1
2435  Lower = IntMin + 1;
2436  Upper = IntMax + 1;
2437  } else if (C->countLeadingZeros() < Width - 1) {
2438  // 'sdiv x, C' produces [INT_MIN / C, INT_MAX / C]
2439  // where C != -1 and C != 0 and C != 1
2440  Lower = IntMin.sdiv(*C);
2441  Upper = IntMax.sdiv(*C);
2442  if (Lower.sgt(Upper))
2443  std::swap(Lower, Upper);
2444  Upper = Upper + 1;
2445  assert(Upper != Lower && "Upper part of range has wrapped!");
2446  }
2447  } else if (match(BO.getOperand(0), m_APInt(C))) {
2448  if (C->isMinSignedValue()) {
2449  // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
2450  Lower = *C;
2451  Upper = Lower.lshr(1) + 1;
2452  } else {
2453  // 'sdiv C, x' produces [-|C|, |C|].
2454  Upper = C->abs() + 1;
2455  Lower = (-Upper) + 1;
2456  }
2457  }
2458  break;
2459 
2460  case Instruction::UDiv:
2461  if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) {
2462  // 'udiv x, C' produces [0, UINT_MAX / C].
2463  Upper = APInt::getMaxValue(Width).udiv(*C) + 1;
2464  } else if (match(BO.getOperand(0), m_APInt(C))) {
2465  // 'udiv C, x' produces [0, C].
2466  Upper = *C + 1;
2467  }
2468  break;
2469 
2470  case Instruction::SRem:
2471  if (match(BO.getOperand(1), m_APInt(C))) {
2472  // 'srem x, C' produces (-|C|, |C|).
2473  Upper = C->abs();
2474  Lower = (-Upper) + 1;
2475  }
2476  break;
2477 
2478  case Instruction::URem:
2479  if (match(BO.getOperand(1), m_APInt(C)))
2480  // 'urem x, C' produces [0, C).
2481  Upper = *C;
2482  break;
2483 
2484  default:
2485  break;
2486  }
2487 }
2488 
2490  Value *RHS) {
2491  const APInt *C;
2492  if (!match(RHS, m_APInt(C)))
2493  return nullptr;
2494 
2495  // Rule out tautological comparisons (eg., ult 0 or uge 0).
2497  if (RHS_CR.isEmptySet())
2498  return ConstantInt::getFalse(GetCompareTy(RHS));
2499  if (RHS_CR.isFullSet())
2500  return ConstantInt::getTrue(GetCompareTy(RHS));
2501 
2502  // Find the range of possible values for binary operators.
2503  unsigned Width = C->getBitWidth();
2504  APInt Lower = APInt(Width, 0);
2505  APInt Upper = APInt(Width, 0);
2506  if (auto *BO = dyn_cast<BinaryOperator>(LHS))
2507  setLimitsForBinOp(*BO, Lower, Upper);
2508 
2509  ConstantRange LHS_CR =
2510  Lower != Upper ? ConstantRange(Lower, Upper) : ConstantRange(Width, true);
2511 
2512  if (auto *I = dyn_cast<Instruction>(LHS))
2513  if (auto *Ranges = I->getMetadata(LLVMContext::MD_range))
2514  LHS_CR = LHS_CR.intersectWith(getConstantRangeFromMetadata(*Ranges));
2515 
2516  if (!LHS_CR.isFullSet()) {
2517  if (RHS_CR.contains(LHS_CR))
2518  return ConstantInt::getTrue(GetCompareTy(RHS));
2519  if (RHS_CR.inverse().contains(LHS_CR))
2520  return ConstantInt::getFalse(GetCompareTy(RHS));
2521  }
2522 
2523  return nullptr;
2524 }
2525 
2526 /// TODO: A large part of this logic is duplicated in InstCombine's
2527 /// foldICmpBinOp(). We should be able to share that and avoid the code
2528 /// duplication.
2530  Value *RHS, const SimplifyQuery &Q,
2531  unsigned MaxRecurse) {
2532  Type *ITy = GetCompareTy(LHS); // The return type.
2533 
2534  BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2535  BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2536  if (MaxRecurse && (LBO || RBO)) {
2537  // Analyze the case when either LHS or RHS is an add instruction.
2538  Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2539  // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2540  bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2541  if (LBO && LBO->getOpcode() == Instruction::Add) {
2542  A = LBO->getOperand(0);
2543  B = LBO->getOperand(1);
2544  NoLHSWrapProblem =
2545  ICmpInst::isEquality(Pred) ||
2546  (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
2547  (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
2548  }
2549  if (RBO && RBO->getOpcode() == Instruction::Add) {
2550  C = RBO->getOperand(0);
2551  D = RBO->getOperand(1);
2552  NoRHSWrapProblem =
2553  ICmpInst::isEquality(Pred) ||
2554  (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2555  (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2556  }
2557 
2558  // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2559  if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2560  if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2561  Constant::getNullValue(RHS->getType()), Q,
2562  MaxRecurse - 1))
2563  return V;
2564 
2565  // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2566  if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2567  if (Value *V =
2569  C == LHS ? D : C, Q, MaxRecurse - 1))
2570  return V;
2571 
2572  // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2573  if (A && C && (A == C || A == D || B == C || B == D) && NoLHSWrapProblem &&
2574  NoRHSWrapProblem) {
2575  // Determine Y and Z in the form icmp (X+Y), (X+Z).
2576  Value *Y, *Z;
2577  if (A == C) {
2578  // C + B == C + D -> B == D
2579  Y = B;
2580  Z = D;
2581  } else if (A == D) {
2582  // D + B == C + D -> B == C
2583  Y = B;
2584  Z = C;
2585  } else if (B == C) {
2586  // A + C == C + D -> A == D
2587  Y = A;
2588  Z = D;
2589  } else {
2590  assert(B == D);
2591  // A + D == C + D -> A == C
2592  Y = A;
2593  Z = C;
2594  }
2595  if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1))
2596  return V;
2597  }
2598  }
2599 
2600  {
2601  Value *Y = nullptr;
2602  // icmp pred (or X, Y), X
2603  if (LBO && match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) {
2604  if (Pred == ICmpInst::ICMP_ULT)
2605  return getFalse(ITy);
2606  if (Pred == ICmpInst::ICMP_UGE)
2607  return getTrue(ITy);
2608 
2609  if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) {
2610  KnownBits RHSKnown = computeKnownBits(RHS, 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 (RHSKnown.isNonNegative() && YKnown.isNegative())
2613  return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy);
2614  if (RHSKnown.isNegative() || YKnown.isNonNegative())
2615  return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy);
2616  }
2617  }
2618  // icmp pred X, (or X, Y)
2619  if (RBO && match(RBO, m_c_Or(m_Value(Y), m_Specific(LHS)))) {
2620  if (Pred == ICmpInst::ICMP_ULE)
2621  return getTrue(ITy);
2622  if (Pred == ICmpInst::ICMP_UGT)
2623  return getFalse(ITy);
2624 
2625  if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLE) {
2626  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2627  KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2628  if (LHSKnown.isNonNegative() && YKnown.isNegative())
2629  return Pred == ICmpInst::ICMP_SGT ? getTrue(ITy) : getFalse(ITy);
2630  if (LHSKnown.isNegative() || YKnown.isNonNegative())
2631  return Pred == ICmpInst::ICMP_SGT ? getFalse(ITy) : getTrue(ITy);
2632  }
2633  }
2634  }
2635 
2636  // icmp pred (and X, Y), X
2637  if (LBO && match(LBO, m_c_And(m_Value(), m_Specific(RHS)))) {
2638  if (Pred == ICmpInst::ICMP_UGT)
2639  return getFalse(ITy);
2640  if (Pred == ICmpInst::ICMP_ULE)
2641  return getTrue(ITy);
2642  }
2643  // icmp pred X, (and X, Y)
2644  if (RBO && match(RBO, m_c_And(m_Value(), m_Specific(LHS)))) {
2645  if (Pred == ICmpInst::ICMP_UGE)
2646  return getTrue(ITy);
2647  if (Pred == ICmpInst::ICMP_ULT)
2648  return getFalse(ITy);
2649  }
2650 
2651  // 0 - (zext X) pred C
2652  if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
2653  if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
2654  if (RHSC->getValue().isStrictlyPositive()) {
2655  if (Pred == ICmpInst::ICMP_SLT)
2656  return ConstantInt::getTrue(RHSC->getContext());
2657  if (Pred == ICmpInst::ICMP_SGE)
2658  return ConstantInt::getFalse(RHSC->getContext());
2659  if (Pred == ICmpInst::ICMP_EQ)
2660  return ConstantInt::getFalse(RHSC->getContext());
2661  if (Pred == ICmpInst::ICMP_NE)
2662  return ConstantInt::getTrue(RHSC->getContext());
2663  }
2664  if (RHSC->getValue().isNonNegative()) {
2665  if (Pred == ICmpInst::ICMP_SLE)
2666  return ConstantInt::getTrue(RHSC->getContext());
2667  if (Pred == ICmpInst::ICMP_SGT)
2668  return ConstantInt::getFalse(RHSC->getContext());
2669  }
2670  }
2671  }
2672 
2673  // icmp pred (urem X, Y), Y
2674  if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2675  switch (Pred) {
2676  default:
2677  break;
2678  case ICmpInst::ICMP_SGT:
2679  case ICmpInst::ICMP_SGE: {
2680  KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2681  if (!Known.isNonNegative())
2682  break;
2684  }
2685  case ICmpInst::ICMP_EQ:
2686  case ICmpInst::ICMP_UGT:
2687  case ICmpInst::ICMP_UGE:
2688  return getFalse(ITy);
2689  case ICmpInst::ICMP_SLT:
2690  case ICmpInst::ICMP_SLE: {
2691  KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2692  if (!Known.isNonNegative())
2693  break;
2695  }
2696  case ICmpInst::ICMP_NE:
2697  case ICmpInst::ICMP_ULT:
2698  case ICmpInst::ICMP_ULE:
2699  return getTrue(ITy);
2700  }
2701  }
2702 
2703  // icmp pred X, (urem Y, X)
2704  if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2705  switch (Pred) {
2706  default:
2707  break;
2708  case ICmpInst::ICMP_SGT:
2709  case ICmpInst::ICMP_SGE: {
2710  KnownBits Known = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2711  if (!Known.isNonNegative())
2712  break;
2714  }
2715  case ICmpInst::ICMP_NE:
2716  case ICmpInst::ICMP_UGT:
2717  case ICmpInst::ICMP_UGE:
2718  return getTrue(ITy);
2719  case ICmpInst::ICMP_SLT:
2720  case ICmpInst::ICMP_SLE: {
2721  KnownBits Known = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2722  if (!Known.isNonNegative())
2723  break;
2725  }
2726  case ICmpInst::ICMP_EQ:
2727  case ICmpInst::ICMP_ULT:
2728  case ICmpInst::ICMP_ULE:
2729  return getFalse(ITy);
2730  }
2731  }
2732 
2733  // x >> y <=u x
2734  // x udiv y <=u x.
2735  if (LBO && (match(LBO, m_LShr(m_Specific(RHS), m_Value())) ||
2736  match(LBO, m_UDiv(m_Specific(RHS), m_Value())))) {
2737  // icmp pred (X op Y), X
2738  if (Pred == ICmpInst::ICMP_UGT)
2739  return getFalse(ITy);
2740  if (Pred == ICmpInst::ICMP_ULE)
2741  return getTrue(ITy);
2742  }
2743 
2744  // x >=u x >> y
2745  // x >=u x udiv y.
2746  if (RBO && (match(RBO, m_LShr(m_Specific(LHS), m_Value())) ||
2747  match(RBO, m_UDiv(m_Specific(LHS), m_Value())))) {
2748  // icmp pred X, (X op Y)
2749  if (Pred == ICmpInst::ICMP_ULT)
2750  return getFalse(ITy);
2751  if (Pred == ICmpInst::ICMP_UGE)
2752  return getTrue(ITy);
2753  }
2754 
2755  // handle:
2756  // CI2 << X == CI
2757  // CI2 << X != CI
2758  //
2759  // where CI2 is a power of 2 and CI isn't
2760  if (auto *CI = dyn_cast<ConstantInt>(RHS)) {
2761  const APInt *CI2Val, *CIVal = &CI->getValue();
2762  if (LBO && match(LBO, m_Shl(m_APInt(CI2Val), m_Value())) &&
2763  CI2Val->isPowerOf2()) {
2764  if (!CIVal->isPowerOf2()) {
2765  // CI2 << X can equal zero in some circumstances,
2766  // this simplification is unsafe if CI is zero.
2767  //
2768  // We know it is safe if:
2769  // - The shift is nsw, we can't shift out the one bit.
2770  // - The shift is nuw, we can't shift out the one bit.
2771  // - CI2 is one
2772  // - CI isn't zero
2773  if (LBO->hasNoSignedWrap() || LBO->hasNoUnsignedWrap() ||
2774  CI2Val->isOneValue() || !CI->isZero()) {
2775  if (Pred == ICmpInst::ICMP_EQ)
2776  return ConstantInt::getFalse(RHS->getContext());
2777  if (Pred == ICmpInst::ICMP_NE)
2778  return ConstantInt::getTrue(RHS->getContext());
2779  }
2780  }
2781  if (CIVal->isSignMask() && CI2Val->isOneValue()) {
2782  if (Pred == ICmpInst::ICMP_UGT)
2783  return ConstantInt::getFalse(RHS->getContext());
2784  if (Pred == ICmpInst::ICMP_ULE)
2785  return ConstantInt::getTrue(RHS->getContext());
2786  }
2787  }
2788  }
2789 
2790  if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2791  LBO->getOperand(1) == RBO->getOperand(1)) {
2792  switch (LBO->getOpcode()) {
2793  default:
2794  break;
2795  case Instruction::UDiv:
2796  case Instruction::LShr:
2797  if (ICmpInst::isSigned(Pred) || !LBO->isExact() || !RBO->isExact())
2798  break;
2799  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2800  RBO->getOperand(0), Q, MaxRecurse - 1))
2801  return V;
2802  break;
2803  case Instruction::SDiv:
2804  if (!ICmpInst::isEquality(Pred) || !LBO->isExact() || !RBO->isExact())
2805  break;
2806  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2807  RBO->getOperand(0), Q, MaxRecurse - 1))
2808  return V;
2809  break;
2810  case Instruction::AShr:
2811  if (!LBO->isExact() || !RBO->isExact())
2812  break;
2813  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2814  RBO->getOperand(0), Q, MaxRecurse - 1))
2815  return V;
2816  break;
2817  case Instruction::Shl: {
2818  bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2819  bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2820  if (!NUW && !NSW)
2821  break;
2822  if (!NSW && ICmpInst::isSigned(Pred))
2823  break;
2824  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2825  RBO->getOperand(0), Q, MaxRecurse - 1))
2826  return V;
2827  break;
2828  }
2829  }
2830  }
2831  return nullptr;
2832 }
2833 
2834 /// Simplify integer comparisons where at least one operand of the compare
2835 /// matches an integer min/max idiom.
2837  Value *RHS, const SimplifyQuery &Q,
2838  unsigned MaxRecurse) {
2839  Type *ITy = GetCompareTy(LHS); // The return type.
2840  Value *A, *B;
2842  CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2843 
2844  // Signed variants on "max(a,b)>=a -> true".
2845  if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2846  if (A != RHS)
2847  std::swap(A, B); // smax(A, B) pred A.
2848  EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2849  // We analyze this as smax(A, B) pred A.
2850  P = Pred;
2851  } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2852  (A == LHS || B == LHS)) {
2853  if (A != LHS)
2854  std::swap(A, B); // A pred smax(A, B).
2855  EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2856  // We analyze this as smax(A, B) swapped-pred A.
2857  P = CmpInst::getSwappedPredicate(Pred);
2858  } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2859  (A == RHS || B == RHS)) {
2860  if (A != RHS)
2861  std::swap(A, B); // smin(A, B) pred A.
2862  EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2863  // We analyze this as smax(-A, -B) swapped-pred -A.
2864  // Note that we do not need to actually form -A or -B thanks to EqP.
2865  P = CmpInst::getSwappedPredicate(Pred);
2866  } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2867  (A == LHS || B == LHS)) {
2868  if (A != LHS)
2869  std::swap(A, B); // A pred smin(A, B).
2870  EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2871  // We analyze this as smax(-A, -B) pred -A.
2872  // Note that we do not need to actually form -A or -B thanks to EqP.
2873  P = Pred;
2874  }
2875  if (P != CmpInst::BAD_ICMP_PREDICATE) {
2876  // Cases correspond to "max(A, B) p A".
2877  switch (P) {
2878  default:
2879  break;
2880  case CmpInst::ICMP_EQ:
2881  case CmpInst::ICMP_SLE:
2882  // Equivalent to "A EqP B". This may be the same as the condition tested
2883  // in the max/min; if so, we can just return that.
2884  if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2885  return V;
2886  if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2887  return V;
2888  // Otherwise, see if "A EqP B" simplifies.
2889  if (MaxRecurse)
2890  if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
2891  return V;
2892  break;
2893  case CmpInst::ICMP_NE:
2894  case CmpInst::ICMP_SGT: {
2896  // Equivalent to "A InvEqP B". This may be the same as the condition
2897  // tested in the max/min; if so, we can just return that.
2898  if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2899  return V;
2900  if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2901  return V;
2902  // Otherwise, see if "A InvEqP B" simplifies.
2903  if (MaxRecurse)
2904  if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
2905  return V;
2906  break;
2907  }
2908  case CmpInst::ICMP_SGE:
2909  // Always true.
2910  return getTrue(ITy);
2911  case CmpInst::ICMP_SLT:
2912  // Always false.
2913  return getFalse(ITy);
2914  }
2915  }
2916 
2917  // Unsigned variants on "max(a,b)>=a -> true".
2919  if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2920  if (A != RHS)
2921  std::swap(A, B); // umax(A, B) pred A.
2922  EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2923  // We analyze this as umax(A, B) pred A.
2924  P = Pred;
2925  } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2926  (A == LHS || B == LHS)) {
2927  if (A != LHS)
2928  std::swap(A, B); // A pred umax(A, B).
2929  EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2930  // We analyze this as umax(A, B) swapped-pred A.
2931  P = CmpInst::getSwappedPredicate(Pred);
2932  } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2933  (A == RHS || B == RHS)) {
2934  if (A != RHS)
2935  std::swap(A, B); // umin(A, B) pred A.
2936  EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2937  // We analyze this as umax(-A, -B) swapped-pred -A.
2938  // Note that we do not need to actually form -A or -B thanks to EqP.
2939  P = CmpInst::getSwappedPredicate(Pred);
2940  } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2941  (A == LHS || B == LHS)) {
2942  if (A != LHS)
2943  std::swap(A, B); // A pred umin(A, B).
2944  EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2945  // We analyze this as umax(-A, -B) pred -A.
2946  // Note that we do not need to actually form -A or -B thanks to EqP.
2947  P = Pred;
2948  }
2949  if (P != CmpInst::BAD_ICMP_PREDICATE) {
2950  // Cases correspond to "max(A, B) p A".
2951  switch (P) {
2952  default:
2953  break;
2954  case CmpInst::ICMP_EQ:
2955  case CmpInst::ICMP_ULE:
2956  // Equivalent to "A EqP B". This may be the same as the condition tested
2957  // in the max/min; if so, we can just return that.
2958  if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2959  return V;
2960  if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2961  return V;
2962  // Otherwise, see if "A EqP B" simplifies.
2963  if (MaxRecurse)
2964  if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
2965  return V;
2966  break;
2967  case CmpInst::ICMP_NE:
2968  case CmpInst::ICMP_UGT: {
2970  // Equivalent to "A InvEqP B". This may be the same as the condition
2971  // tested in the max/min; if so, we can just return that.
2972  if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2973  return V;
2974  if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2975  return V;
2976  // Otherwise, see if "A InvEqP B" simplifies.
2977  if (MaxRecurse)
2978  if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
2979  return V;
2980  break;
2981  }
2982  case CmpInst::ICMP_UGE:
2983  // Always true.
2984  return getTrue(ITy);
2985  case CmpInst::ICMP_ULT:
2986  // Always false.
2987  return getFalse(ITy);
2988  }
2989  }
2990 
2991  // Variants on "max(x,y) >= min(x,z)".
2992  Value *C, *D;
2993  if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2994  match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2995  (A == C || A == D || B == C || B == D)) {
2996  // max(x, ?) pred min(x, ?).
2997  if (Pred == CmpInst::ICMP_SGE)
2998  // Always true.
2999  return getTrue(ITy);
3000  if (Pred == CmpInst::ICMP_SLT)
3001  // Always false.
3002  return getFalse(ITy);
3003  } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
3004  match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
3005  (A == C || A == D || B == C || B == D)) {
3006  // min(x, ?) pred max(x, ?).
3007  if (Pred == CmpInst::ICMP_SLE)
3008  // Always true.
3009  return getTrue(ITy);
3010  if (Pred == CmpInst::ICMP_SGT)
3011  // Always false.
3012  return getFalse(ITy);
3013  } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
3014  match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
3015  (A == C || A == D || B == C || B == D)) {
3016  // max(x, ?) pred min(x, ?).
3017  if (Pred == CmpInst::ICMP_UGE)
3018  // Always true.
3019  return getTrue(ITy);
3020  if (Pred == CmpInst::ICMP_ULT)
3021  // Always false.
3022  return getFalse(ITy);
3023  } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
3024  match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
3025  (A == C || A == D || B == C || B == D)) {
3026  // min(x, ?) pred max(x, ?).
3027  if (Pred == CmpInst::ICMP_ULE)
3028  // Always true.
3029  return getTrue(ITy);
3030  if (Pred == CmpInst::ICMP_UGT)
3031  // Always false.
3032  return getFalse(ITy);
3033  }
3034 
3035  return nullptr;
3036 }
3037 
3038 /// Given operands for an ICmpInst, see if we can fold the result.
3039 /// If not, this returns null.
3040 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3041  const SimplifyQuery &Q, unsigned MaxRecurse) {
3042  CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3043  assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
3044 
3045  if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3046  if (Constant *CRHS = dyn_cast<Constant>(RHS))
3047  return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3048 
3049  // If we have a constant, make sure it is on the RHS.
3050  std::swap(LHS, RHS);
3051  Pred = CmpInst::getSwappedPredicate(Pred);
3052  }
3053 
3054  Type *ITy = GetCompareTy(LHS); // The return type.
3055 
3056  // icmp X, X -> true/false
3057  // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
3058  // because X could be 0.
3059  if (LHS == RHS || isa<UndefValue>(RHS))
3060  return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
3061 
3062  if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
3063  return V;
3064 
3065  if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
3066  return V;
3067 
3068  if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS))
3069  return V;
3070 
3071  // If both operands have range metadata, use the metadata
3072  // to simplify the comparison.
3073  if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) {
3074  auto RHS_Instr = cast<Instruction>(RHS);
3075  auto LHS_Instr = cast<Instruction>(LHS);
3076 
3077  if (RHS_Instr->getMetadata(LLVMContext::MD_range) &&
3078  LHS_Instr->getMetadata(LLVMContext::MD_range)) {
3079  auto RHS_CR = getConstantRangeFromMetadata(
3080  *RHS_Instr->getMetadata(LLVMContext::MD_range));
3081  auto LHS_CR = getConstantRangeFromMetadata(
3082  *LHS_Instr->getMetadata(LLVMContext::MD_range));
3083 
3084  auto Satisfied_CR = ConstantRange::makeSatisfyingICmpRegion(Pred, RHS_CR);
3085  if (Satisfied_CR.contains(LHS_CR))
3086  return ConstantInt::getTrue(RHS->getContext());
3087 
3088  auto InversedSatisfied_CR = ConstantRange::makeSatisfyingICmpRegion(
3089  CmpInst::getInversePredicate(Pred), RHS_CR);
3090  if (InversedSatisfied_CR.contains(LHS_CR))
3091  return ConstantInt::getFalse(RHS->getContext());
3092  }
3093  }
3094 
3095  // Compare of cast, for example (zext X) != 0 -> X != 0
3096  if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
3097  Instruction *LI = cast<CastInst>(LHS);
3098  Value *SrcOp = LI->getOperand(0);
3099  Type *SrcTy = SrcOp->getType();
3100  Type *DstTy = LI->getType();
3101 
3102  // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
3103  // if the integer type is the same size as the pointer type.
3104  if (MaxRecurse && isa<PtrToIntInst>(LI) &&
3105  Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
3106  if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
3107  // Transfer the cast to the constant.
3108  if (Value *V = SimplifyICmpInst(Pred, SrcOp,
3109  ConstantExpr::getIntToPtr(RHSC, SrcTy),
3110  Q, MaxRecurse-1))
3111  return V;
3112  } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
3113  if (RI->getOperand(0)->getType() == SrcTy)
3114  // Compare without the cast.
3115  if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
3116  Q, MaxRecurse-1))
3117  return V;
3118  }
3119  }
3120 
3121  if (isa<ZExtInst>(LHS)) {
3122  // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
3123  // same type.
3124  if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
3125  if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3126  // Compare X and Y. Note that signed predicates become unsigned.
3128  SrcOp, RI->getOperand(0), Q,
3129  MaxRecurse-1))
3130  return V;
3131  }
3132  // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
3133  // too. If not, then try to deduce the result of the comparison.
3134  else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
3135  // Compute the constant that would happen if we truncated to SrcTy then
3136  // reextended to DstTy.
3137  Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
3138  Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
3139 
3140  // If the re-extended constant didn't change then this is effectively
3141  // also a case of comparing two zero-extended values.
3142  if (RExt == CI && MaxRecurse)
3144  SrcOp, Trunc, Q, MaxRecurse-1))
3145  return V;
3146 
3147  // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
3148  // there. Use this to work out the result of the comparison.
3149  if (RExt != CI) {
3150  switch (Pred) {
3151  default: llvm_unreachable("Unknown ICmp predicate!");
3152  // LHS <u RHS.
3153  case ICmpInst::ICMP_EQ:
3154  case ICmpInst::ICMP_UGT:
3155  case ICmpInst::ICMP_UGE:
3156  return ConstantInt::getFalse(CI->getContext());
3157 
3158  case ICmpInst::ICMP_NE:
3159  case ICmpInst::ICMP_ULT:
3160  case ICmpInst::ICMP_ULE:
3161  return ConstantInt::getTrue(CI->getContext());
3162 
3163  // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
3164  // is non-negative then LHS <s RHS.
3165  case ICmpInst::ICMP_SGT:
3166  case ICmpInst::ICMP_SGE:
3167  return CI->getValue().isNegative() ?
3168  ConstantInt::getTrue(CI->getContext()) :
3169  ConstantInt::getFalse(CI->getContext());
3170 
3171  case ICmpInst::ICMP_SLT:
3172  case ICmpInst::ICMP_SLE:
3173  return CI->getValue().isNegative() ?
3174  ConstantInt::getFalse(CI->getContext()) :
3175  ConstantInt::getTrue(CI->getContext());
3176  }
3177  }
3178  }
3179  }
3180 
3181  if (isa<SExtInst>(LHS)) {
3182  // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
3183  // same type.
3184  if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
3185  if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3186  // Compare X and Y. Note that the predicate does not change.
3187  if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
3188  Q, MaxRecurse-1))
3189  return V;
3190  }
3191  // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
3192  // too. If not, then try to deduce the result of the comparison.
3193  else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
3194  // Compute the constant that would happen if we truncated to SrcTy then
3195  // reextended to DstTy.
3196  Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
3197  Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
3198 
3199  // If the re-extended constant didn't change then this is effectively
3200  // also a case of comparing two sign-extended values.
3201  if (RExt == CI && MaxRecurse)
3202  if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
3203  return V;
3204 
3205  // Otherwise the upper bits of LHS are all equal, while RHS has varying
3206  // bits there. Use this to work out the result of the comparison.
3207  if (RExt != CI) {
3208  switch (Pred) {
3209  default: llvm_unreachable("Unknown ICmp predicate!");
3210  case ICmpInst::ICMP_EQ:
3211  return ConstantInt::getFalse(CI->getContext());
3212  case ICmpInst::ICMP_NE:
3213  return ConstantInt::getTrue(CI->getContext());
3214 
3215  // If RHS is non-negative then LHS <s RHS. If RHS is negative then
3216  // LHS >s RHS.
3217  case ICmpInst::ICMP_SGT:
3218  case ICmpInst::ICMP_SGE:
3219  return CI->getValue().isNegative() ?
3220  ConstantInt::getTrue(CI->getContext()) :
3221  ConstantInt::getFalse(CI->getContext());
3222  case ICmpInst::ICMP_SLT:
3223  case ICmpInst::ICMP_SLE:
3224  return CI->getValue().isNegative() ?
3225  ConstantInt::getFalse(CI->getContext()) :
3226  ConstantInt::getTrue(CI->getContext());
3227 
3228  // If LHS is non-negative then LHS <u RHS. If LHS is negative then
3229  // LHS >u RHS.
3230  case ICmpInst::ICMP_UGT:
3231  case ICmpInst::ICMP_UGE:
3232  // Comparison is true iff the LHS <s 0.
3233  if (MaxRecurse)
3234  if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
3235  Constant::getNullValue(SrcTy),
3236  Q, MaxRecurse-1))
3237  return V;
3238  break;
3239  case ICmpInst::ICMP_ULT:
3240  case ICmpInst::ICMP_ULE:
3241  // Comparison is true iff the LHS >=s 0.
3242  if (MaxRecurse)
3243  if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
3244  Constant::getNullValue(SrcTy),
3245  Q, MaxRecurse-1))
3246  return V;
3247  break;
3248  }
3249  }
3250  }
3251  }
3252  }
3253 
3254  // icmp eq|ne X, Y -> false|true if X != Y
3255  if (ICmpInst::isEquality(Pred) &&
3256  isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT)) {
3257  return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy);
3258  }
3259 
3260  if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse))
3261  return V;
3262 
3263  if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse))
3264  return V;
3265 
3266  // Simplify comparisons of related pointers using a powerful, recursive
3267  // GEP-walk when we have target data available..
3268  if (LHS->getType()->isPointerTy())
3269  if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.AC, Q.CxtI, LHS,
3270  RHS))
3271  return C;
3272  if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS))
3273  if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS))
3274  if (Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) ==
3275  Q.DL.getTypeSizeInBits(CLHS->getType()) &&
3276  Q.DL.getTypeSizeInBits(CRHS->getPointerOperandType()) ==
3277  Q.DL.getTypeSizeInBits(CRHS->getType()))
3278  if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.AC, Q.CxtI,
3279  CLHS->getPointerOperand(),
3280  CRHS->getPointerOperand()))
3281  return C;
3282 
3283  if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
3284  if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
3285  if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
3286  GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
3287  (ICmpInst::isEquality(Pred) ||
3288  (GLHS->isInBounds() && GRHS->isInBounds() &&
3289  Pred == ICmpInst::getSignedPredicate(Pred)))) {
3290  // The bases are equal and the indices are constant. Build a constant
3291  // expression GEP with the same indices and a null base pointer to see
3292  // what constant folding can make out of it.
3293  Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
3294  SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
3296  GLHS->getSourceElementType(), Null, IndicesLHS);
3297 
3298  SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
3300  GLHS->getSourceElementType(), Null, IndicesRHS);
3301  return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
3302  }
3303  }
3304  }
3305 
3306  // If the comparison is with the result of a select instruction, check whether
3307  // comparing with either branch of the select always yields the same value.
3308  if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3309  if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3310  return V;
3311 
3312  // If the comparison is with the result of a phi instruction, check whether
3313  // doing the compare with each incoming phi value yields a common result.
3314  if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3315  if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3316  return V;
3317 
3318  return nullptr;
3319 }
3320 
3321 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3322  const SimplifyQuery &Q) {
3323  return ::SimplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
3324 }
3325 
3326 /// Given operands for an FCmpInst, see if we can fold the result.
3327 /// If not, this returns null.
3328 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3329  FastMathFlags FMF, const SimplifyQuery &Q,
3330  unsigned MaxRecurse) {
3331  CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3332  assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
3333 
3334  if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3335  if (Constant *CRHS = dyn_cast<Constant>(RHS))
3336  return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3337 
3338  // If we have a constant, make sure it is on the RHS.
3339  std::swap(LHS, RHS);
3340  Pred = CmpInst::getSwappedPredicate(Pred);
3341  }
3342 
3343  // Fold trivial predicates.
3344  Type *RetTy = GetCompareTy(LHS);
3345  if (Pred == FCmpInst::FCMP_FALSE)
3346  return getFalse(RetTy);
3347  if (Pred == FCmpInst::FCMP_TRUE)
3348  return getTrue(RetTy);
3349 
3350  // UNO/ORD predicates can be trivially folded if NaNs are ignored.
3351  if (FMF.noNaNs()) {
3352  if (Pred == FCmpInst::FCMP_UNO)
3353  return getFalse(RetTy);
3354  if (Pred == FCmpInst::FCMP_ORD)
3355  return getTrue(RetTy);
3356  }
3357 
3358  // fcmp pred x, undef and fcmp pred undef, x
3359  // fold to true if unordered, false if ordered
3360  if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS)) {
3361  // Choosing NaN for the undef will always make unordered comparison succeed
3362  // and ordered comparison fail.
3363  return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
3364  }
3365 
3366  // fcmp x,x -> true/false. Not all compares are foldable.
3367  if (LHS == RHS) {
3368  if (CmpInst::isTrueWhenEqual(Pred))
3369  return getTrue(RetTy);
3370  if (CmpInst::isFalseWhenEqual(Pred))
3371  return getFalse(RetTy);
3372  }
3373 
3374  // Handle fcmp with constant RHS.
3375  const APFloat *C;
3376  if (match(RHS, m_APFloat(C))) {
3377  // If the constant is a nan, see if we can fold the comparison based on it.
3378  if (C->isNaN()) {
3379  if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
3380  return getFalse(RetTy);
3381  assert(FCmpInst::isUnordered(Pred) &&
3382  "Comparison must be either ordered or unordered!");
3383  // True if unordered.
3384  return getTrue(RetTy);
3385  }
3386  // Check whether the constant is an infinity.
3387  if (C->isInfinity()) {
3388  if (C->isNegative()) {
3389  switch (Pred) {
3390  case FCmpInst::FCMP_OLT:
3391  // No value is ordered and less than negative infinity.
3392  return getFalse(RetTy);
3393  case FCmpInst::FCMP_UGE:
3394  // All values are unordered with or at least negative infinity.
3395  return getTrue(RetTy);
3396  default:
3397  break;
3398  }
3399  } else {
3400  switch (Pred) {
3401  case FCmpInst::FCMP_OGT:
3402  // No value is ordered and greater than infinity.
3403  return getFalse(RetTy);
3404  case FCmpInst::FCMP_ULE:
3405  // All values are unordered with and at most infinity.
3406  return getTrue(RetTy);
3407  default:
3408  break;
3409  }
3410  }
3411  }
3412  if (C->isZero()) {
3413  switch (Pred) {
3414  case FCmpInst::FCMP_UGE:
3415  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3416  return getTrue(RetTy);
3417  break;
3418  case FCmpInst::FCMP_OLT:
3419  // X < 0
3420  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3421  return getFalse(RetTy);
3422  break;
3423  default:
3424  break;
3425  }
3426  } else if (C->isNegative()) {
3427  assert(!C->isNaN() && "Unexpected NaN constant!");
3428  // TODO: We can catch more cases by using a range check rather than
3429  // relying on CannotBeOrderedLessThanZero.
3430  switch (Pred) {
3431  case FCmpInst::FCMP_UGE:
3432  case FCmpInst::FCMP_UGT:
3433  case FCmpInst::FCMP_UNE:
3434  // (X >= 0) implies (X > C) when (C < 0)
3435  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3436  return getTrue(RetTy);
3437  break;
3438  case FCmpInst::FCMP_OEQ:
3439  case FCmpInst::FCMP_OLE:
3440  case FCmpInst::FCMP_OLT:
3441  // (X >= 0) implies !(X < C) when (C < 0)
3442  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3443  return getFalse(RetTy);
3444  break;
3445  default:
3446  break;
3447  }
3448  }
3449  }
3450 
3451  // If the comparison is with the result of a select instruction, check whether
3452  // comparing with either branch of the select always yields the same value.
3453  if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3454  if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3455  return V;
3456 
3457  // If the comparison is with the result of a phi instruction, check whether
3458  // doing the compare with each incoming phi value yields a common result.
3459  if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3460  if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3461  return V;
3462 
3463  return nullptr;
3464 }
3465 
3466 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3467  FastMathFlags FMF, const SimplifyQuery &Q) {
3468  return ::SimplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit);
3469 }
3470 
3471 /// See if V simplifies when its operand Op is replaced with RepOp.
3472 static const Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
3473  const SimplifyQuery &Q,
3474  unsigned MaxRecurse) {
3475  // Trivial replacement.
3476  if (V == Op)
3477  return RepOp;
3478 
3479  // We cannot replace a constant, and shouldn't even try.
3480  if (isa<Constant>(Op))
3481  return nullptr;
3482 
3483  auto *I = dyn_cast<Instruction>(V);
3484  if (!I)
3485  return nullptr;
3486 
3487  // If this is a binary operator, try to simplify it with the replaced op.
3488  if (auto *B = dyn_cast<BinaryOperator>(I)) {
3489  // Consider:
3490  // %cmp = icmp eq i32 %x, 2147483647
3491  // %add = add nsw i32 %x, 1
3492  // %sel = select i1 %cmp, i32 -2147483648, i32 %add
3493  //
3494  // We can't replace %sel with %add unless we strip away the flags.
3495  if (isa<OverflowingBinaryOperator>(B))
3496  if (B->hasNoSignedWrap() || B->hasNoUnsignedWrap())
3497  return nullptr;
3498  if (isa<PossiblyExactOperator>(B))
3499  if (B->isExact())
3500  return nullptr;
3501 
3502  if (MaxRecurse) {
3503  if (B->getOperand(0) == Op)
3504  return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), Q,
3505  MaxRecurse - 1);
3506  if (B->getOperand(1) == Op)
3507  return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, Q,
3508  MaxRecurse - 1);
3509  }
3510  }
3511 
3512  // Same for CmpInsts.
3513  if (CmpInst *C = dyn_cast<CmpInst>(I)) {
3514  if (MaxRecurse) {
3515  if (C->getOperand(0) == Op)
3516  return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), Q,
3517  MaxRecurse - 1);
3518  if (C->getOperand(1) == Op)
3519  return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, Q,
3520  MaxRecurse - 1);
3521  }
3522  }
3523 
3524  // TODO: We could hand off more cases to instsimplify here.
3525 
3526  // If all operands are constant after substituting Op for RepOp then we can
3527  // constant fold the instruction.
3528  if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) {
3529  // Build a list of all constant operands.
3530  SmallVector<Constant *, 8> ConstOps;
3531  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
3532  if (I->getOperand(i) == Op)
3533  ConstOps.push_back(CRepOp);
3534  else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i)))
3535  ConstOps.push_back(COp);
3536  else
3537  break;
3538  }
3539 
3540  // All operands were constants, fold it.
3541  if (ConstOps.size() == I->getNumOperands()) {
3542  if (CmpInst *C = dyn_cast<CmpInst>(I))
3543  return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0],
3544  ConstOps[1], Q.DL, Q.TLI);
3545 
3546  if (LoadInst *LI = dyn_cast<LoadInst>(I))
3547  if (!LI->isVolatile())
3548  return ConstantFoldLoadFromConstPtr(ConstOps[0], LI->getType(), Q.DL);
3549 
3550  return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI);
3551  }
3552  }
3553 
3554  return nullptr;
3555 }
3556 
3557 /// Try to simplify a select instruction when its condition operand is an
3558 /// integer comparison where one operand of the compare is a constant.
3559 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X,
3560  const APInt *Y, bool TrueWhenUnset) {
3561  const APInt *C;
3562 
3563  // (X & Y) == 0 ? X & ~Y : X --> X
3564  // (X & Y) != 0 ? X & ~Y : X --> X & ~Y
3565  if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) &&
3566  *Y == ~*C)
3567  return TrueWhenUnset ? FalseVal : TrueVal;
3568 
3569  // (X & Y) == 0 ? X : X & ~Y --> X & ~Y
3570  // (X & Y) != 0 ? X : X & ~Y --> X
3571  if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) &&
3572  *Y == ~*C)
3573  return TrueWhenUnset ? FalseVal : TrueVal;
3574 
3575  if (Y->isPowerOf2()) {
3576  // (X & Y) == 0 ? X | Y : X --> X | Y
3577  // (X & Y) != 0 ? X | Y : X --> X
3578  if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) &&
3579  *Y == *C)
3580  return TrueWhenUnset ? TrueVal : FalseVal;
3581 
3582  // (X & Y) == 0 ? X : X | Y --> X
3583  // (X & Y) != 0 ? X : X | Y --> X | Y
3584  if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) &&
3585  *Y == *C)
3586  return TrueWhenUnset ? TrueVal : FalseVal;
3587  }
3588 
3589  return nullptr;
3590 }
3591 
3592 /// An alternative way to test if a bit is set or not uses sgt/slt instead of
3593 /// eq/ne.
3595  ICmpInst::Predicate Pred,
3596  Value *TrueVal, Value *FalseVal) {
3597  Value *X;
3598  APInt Mask;
3599  if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask))
3600  return nullptr;
3601 
3602  return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask,
3603  Pred == ICmpInst::ICMP_EQ);
3604 }
3605 
3606 /// Try to simplify a select instruction when its condition operand is an
3607 /// integer comparison.
3608 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
3609  Value *FalseVal, const SimplifyQuery &Q,
3610  unsigned MaxRecurse) {
3611  ICmpInst::Predicate Pred;
3612  Value *CmpLHS, *CmpRHS;
3613  if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
3614  return nullptr;
3615 
3616  if (ICmpInst::isEquality(Pred) && match(CmpRHS, m_Zero())) {
3617  Value *X;
3618  const APInt *Y;
3619  if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y))))
3620  if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y,
3621  Pred == ICmpInst::ICMP_EQ))
3622  return V;
3623  }
3624 
3625  // Check for other compares that behave like bit test.
3626  if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred,
3627  TrueVal, FalseVal))
3628  return V;
3629 
3630  if (CondVal->hasOneUse()) {
3631  const APInt *C;
3632  if (match(CmpRHS, m_APInt(C))) {
3633  // X < MIN ? T : F --> F
3634  if (Pred == ICmpInst::ICMP_SLT && C->isMinSignedValue())
3635  return FalseVal;
3636  // X < MIN ? T : F --> F
3637  if (Pred == ICmpInst::ICMP_ULT && C->isMinValue())
3638  return FalseVal;
3639  // X > MAX ? T : F --> F
3640  if (Pred == ICmpInst::ICMP_SGT && C->isMaxSignedValue())
3641  return FalseVal;
3642  // X > MAX ? T : F --> F
3643  if (Pred == ICmpInst::ICMP_UGT && C->isMaxValue())
3644  return FalseVal;
3645  }
3646  }
3647 
3648  // If we have an equality comparison, then we know the value in one of the
3649  // arms of the select. See if substituting this value into the arm and
3650  // simplifying the result yields the same value as the other arm.
3651  if (Pred == ICmpInst::ICMP_EQ) {
3652  if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3653  TrueVal ||
3654  SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3655  TrueVal)
3656  return FalseVal;
3657  if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3658  FalseVal ||
3659  SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3660  FalseVal)
3661  return FalseVal;
3662  } else if (Pred == ICmpInst::ICMP_NE) {
3663  if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3664  FalseVal ||
3665  SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3666  FalseVal)
3667  return TrueVal;
3668  if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3669  TrueVal ||
3670  SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3671  TrueVal)
3672  return TrueVal;
3673  }
3674 
3675  return nullptr;
3676 }
3677 
3678 /// Given operands for a SelectInst, see if we can fold the result.
3679 /// If not, this returns null.
3680 static Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3681  const SimplifyQuery &Q, unsigned MaxRecurse) {
3682  if (auto *CondC = dyn_cast<Constant>(Cond)) {
3683  if (auto *TrueC = dyn_cast<Constant>(TrueVal))
3684  if (auto *FalseC = dyn_cast<Constant>(FalseVal))
3685  return ConstantFoldSelectInstruction(CondC, TrueC, FalseC);
3686 
3687  // select undef, X, Y -> X or Y
3688  if (isa<UndefValue>(CondC))
3689  return isa<Constant>(FalseVal) ? FalseVal : TrueVal;
3690 
3691  // TODO: Vector constants with undef elements don't simplify.
3692 
3693  // select true, X, Y -> X
3694  if (CondC->isAllOnesValue())
3695  return TrueVal;
3696  // select false, X, Y -> Y
3697  if (CondC->isNullValue())
3698  return FalseVal;
3699  }
3700 
3701  // select ?, X, X -> X
3702  if (TrueVal == FalseVal)
3703  return TrueVal;
3704 
3705  if (isa<UndefValue>(TrueVal)) // select ?, undef, X -> X
3706  return FalseVal;
3707  if (isa<UndefValue>(FalseVal)) // select ?, X, undef -> X
3708  return TrueVal;
3709 
3710  if (Value *V =
3711  simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse))
3712  return V;
3713 
3714  return nullptr;
3715 }
3716 
3717 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3718  const SimplifyQuery &Q) {
3719  return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit);
3720 }
3721 
3722 /// Given operands for an GetElementPtrInst, see if we can fold the result.
3723 /// If not, this returns null.
3725  const SimplifyQuery &Q, unsigned) {
3726  // The type of the GEP pointer operand.
3727  unsigned AS =
3728  cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace();
3729 
3730  // getelementptr P -> P.
3731  if (Ops.size() == 1)
3732  return Ops[0];
3733 
3734  // Compute the (pointer) type returned by the GEP instruction.
3735  Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1));
3736  Type *GEPTy = PointerType::get(LastType, AS);
3737  if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
3738  GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3739  else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType()))
3740  GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3741 
3742  if (isa<UndefValue>(Ops[0]))
3743  return UndefValue::get(GEPTy);
3744 
3745  if (Ops.size() == 2) {
3746  // getelementptr P, 0 -> P.
3747  if (match(Ops[1], m_Zero()))
3748  return Ops[0];
3749 
3750  Type *Ty = SrcTy;
3751  if (Ty->isSized()) {
3752  Value *P;
3753  uint64_t C;
3754  uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty);
3755  // getelementptr P, N -> P if P points to a type of zero size.
3756  if (TyAllocSize == 0)
3757  return Ops[0];
3758 
3759  // The following transforms are only safe if the ptrtoint cast
3760  // doesn't truncate the pointers.
3761  if (Ops[1]->getType()->getScalarSizeInBits() ==
3762  Q.DL.getIndexSizeInBits(AS)) {
3763  auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * {
3764  if (match(P, m_Zero()))
3765  return Constant::getNullValue(GEPTy);
3766  Value *Temp;
3767  if (match(P, m_PtrToInt(m_Value(Temp))))
3768  if (Temp->getType() == GEPTy)
3769  return Temp;
3770  return nullptr;
3771  };
3772 
3773  // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
3774  if (TyAllocSize == 1 &&
3775  match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0])))))
3776  if (Value *R = PtrToIntOrZero(P))
3777  return R;
3778 
3779  // getelementptr V, (ashr (sub P, V), C) -> Q
3780  // if P points to a type of size 1 << C.
3781  if (match(Ops[1],
3782  m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3783  m_ConstantInt(C))) &&
3784  TyAllocSize == 1ULL << C)
3785  if (Value *R = PtrToIntOrZero(P))
3786  return R;
3787 
3788  // getelementptr V, (sdiv (sub P, V), C) -> Q
3789  // if P points to a type of size C.
3790  if (match(Ops[1],
3791  m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3792  m_SpecificInt(TyAllocSize))))
3793  if (Value *R = PtrToIntOrZero(P))
3794  return R;
3795  }
3796  }
3797  }
3798 
3799  if (Q.DL.getTypeAllocSize(LastType) == 1 &&
3800  all_of(Ops.slice(1).drop_back(1),
3801  [](Value *Idx) { return match(Idx, m_Zero()); })) {
3802  unsigned IdxWidth =
3803  Q.DL.getIndexSizeInBits(Ops[0]->getType()->getPointerAddressSpace());
3804  if (Q.DL.getTypeSizeInBits(Ops.back()->getType()) == IdxWidth) {
3805  APInt BasePtrOffset(IdxWidth, 0);
3806  Value *StrippedBasePtr =
3807  Ops[0]->stripAndAccumulateInBoundsConstantOffsets(Q.DL,
3808  BasePtrOffset);
3809 
3810  // gep (gep V, C), (sub 0, V) -> C
3811  if (match(Ops.back(),
3812  m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr))))) {
3813  auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset);
3814  return ConstantExpr::getIntToPtr(CI, GEPTy);
3815  }
3816  // gep (gep V, C), (xor V, -1) -> C-1
3817  if (match(Ops.back(),
3818  m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes()))) {
3819  auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1);
3820  return ConstantExpr::getIntToPtr(CI, GEPTy);
3821  }
3822  }
3823  }
3824 
3825  // Check to see if this is constant foldable.
3826  if (!all_of(Ops, [](Value *V) { return isa<Constant>(V); }))
3827  return nullptr;
3828 
3829  auto *CE = ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]),
3830  Ops.slice(1));
3831  if (auto *CEFolded = ConstantFoldConstant(CE, Q.DL))
3832  return CEFolded;
3833  return CE;
3834 }
3835 
3837  const SimplifyQuery &Q) {
3838  return ::SimplifyGEPInst(SrcTy, Ops, Q, RecursionLimit);
3839 }
3840 
3841 /// Given operands for an InsertValueInst, see if we can fold the result.
3842 /// If not, this returns null.
3844  ArrayRef<unsigned> Idxs, const SimplifyQuery &Q,
3845  unsigned) {
3846  if (Constant *CAgg = dyn_cast<Constant>(Agg))
3847  if (Constant *CVal = dyn_cast<Constant>(Val))
3848  return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
3849 
3850  // insertvalue x, undef, n -> x
3851  if (match(Val, m_Undef()))
3852  return Agg;
3853 
3854  // insertvalue x, (extractvalue y, n), n
3855  if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
3856  if (EV->getAggregateOperand()->getType() == Agg->getType() &&
3857  EV->getIndices() == Idxs) {
3858  // insertvalue undef, (extractvalue y, n), n -> y
3859  if (match(Agg, m_Undef()))
3860  return EV->getAggregateOperand();
3861 
3862  // insertvalue y, (extractvalue y, n), n -> y
3863  if (Agg == EV->getAggregateOperand())
3864  return Agg;
3865  }
3866 
3867  return nullptr;
3868 }
3869 
3871  ArrayRef<unsigned> Idxs,
3872  const SimplifyQuery &Q) {
3874 }
3875 
3877  const SimplifyQuery &Q) {
3878  // Try to constant fold.
3879  auto *VecC = dyn_cast<Constant>(Vec);
3880  auto *ValC = dyn_cast<Constant>(Val);
3881  auto *IdxC = dyn_cast<Constant>(Idx);
3882  if (VecC && ValC && IdxC)
3883  return ConstantFoldInsertElementInstruction(VecC, ValC, IdxC);
3884 
3885  // Fold into undef if index is out of bounds.
3886  if (auto *CI = dyn_cast<ConstantInt>(Idx)) {
3887  uint64_t NumElements = cast<VectorType>(Vec->getType())->getNumElements();
3888  if (CI->uge(NumElements))
3889  return UndefValue::get(Vec->getType());
3890  }
3891 
3892  // If index is undef, it might be out of bounds (see above case)
3893  if (isa<UndefValue>(Idx))
3894  return UndefValue::get(Vec->getType());
3895 
3896  return nullptr;
3897 }
3898 
3899 /// Given operands for an ExtractValueInst, see if we can fold the result.
3900 /// If not, this returns null.
3902  const SimplifyQuery &, unsigned) {
3903  if (auto *CAgg = dyn_cast<Constant>(Agg))
3904  return ConstantFoldExtractValueInstruction(CAgg, Idxs);
3905 
3906  // extractvalue x, (insertvalue y, elt, n), n -> elt
3907  unsigned NumIdxs = Idxs.size();
3908  for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr;
3909  IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) {
3910  ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices();
3911  unsigned NumInsertValueIdxs = InsertValueIdxs.size();
3912  unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs);
3913  if (InsertValueIdxs.slice(0, NumCommonIdxs) ==
3914  Idxs.slice(0, NumCommonIdxs)) {
3915  if (NumIdxs == NumInsertValueIdxs)
3916  return IVI->getInsertedValueOperand();
3917  break;
3918  }
3919  }
3920 
3921  return nullptr;
3922 }
3923 
3925  const SimplifyQuery &Q) {
3927 }
3928 
3929 /// Given operands for an ExtractElementInst, see if we can fold the result.
3930 /// If not, this returns null.
3932  unsigned) {
3933  if (auto *CVec = dyn_cast<Constant>(Vec)) {
3934  if (auto *CIdx = dyn_cast<Constant>(Idx))
3935  return ConstantFoldExtractElementInstruction(CVec, CIdx);
3936 
3937  // The index is not relevant if our vector is a splat.
3938  if (auto *Splat = CVec->getSplatValue())
3939  return Splat;
3940 
3941  if (isa<UndefValue>(Vec))
3942  return UndefValue::get(Vec->getType()->getVectorElementType());
3943  }
3944 
3945  // If extracting a specified index from the vector, see if we can recursively
3946  // find a previously computed scalar that was inserted into the vector.
3947  if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) {
3948  if (IdxC->getValue().uge(Vec->getType()->getVectorNumElements()))
3949  // definitely out of bounds, thus undefined result
3950  return UndefValue::get(Vec->getType()->getVectorElementType());
3951  if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
3952  return Elt;
3953  }
3954 
3955  // An undef extract index can be arbitrarily chosen to be an out-of-range
3956  // index value, which would result in the instruction being undef.
3957  if (isa<UndefValue>(Idx))
3958  return UndefValue::get(Vec->getType()->getVectorElementType());
3959 
3960  return nullptr;
3961 }
3962 
3964  const SimplifyQuery &Q) {
3966 }
3967 
3968 /// See if we can fold the given phi. If not, returns null.
3969 static Value *SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q) {
3970  // If all of the PHI's incoming values are the same then replace the PHI node
3971  // with the common value.
3972  Value *CommonValue = nullptr;
3973  bool HasUndefInput = false;
3974  for (Value *Incoming : PN->incoming_values()) {
3975  // If the incoming value is the phi node itself, it can safely be skipped.
3976  if (Incoming == PN) continue;
3977  if (isa<UndefValue>(Incoming)) {
3978  // Remember that we saw an undef value, but otherwise ignore them.
3979  HasUndefInput = true;
3980  continue;
3981  }
3982  if (CommonValue && Incoming != CommonValue)
3983  return nullptr; // Not the same, bail out.
3984  CommonValue = Incoming;
3985  }
3986 
3987  // If CommonValue is null then all of the incoming values were either undef or
3988  // equal to the phi node itself.
3989  if (!CommonValue)
3990  return UndefValue::get(PN->getType());
3991 
3992  // If we have a PHI node like phi(X, undef, X), where X is defined by some
3993  // instruction, we cannot return X as the result of the PHI node unless it
3994  // dominates the PHI block.
3995  if (HasUndefInput)
3996  return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr;
3997 
3998  return CommonValue;
3999 }
4000 
4001 static Value *SimplifyCastInst(unsigned CastOpc, Value *Op,
4002  Type *Ty, const SimplifyQuery &Q, unsigned MaxRecurse) {
4003  if (auto *C = dyn_cast<Constant>(Op))
4004  return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL);
4005 
4006  if (auto *CI = dyn_cast<CastInst>(Op)) {
4007  auto *Src = CI->getOperand(0);
4008  Type *SrcTy = Src->getType();
4009  Type *MidTy = CI->getType();
4010  Type *DstTy = Ty;
4011  if (Src->getType() == Ty) {
4012  auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode());
4013  auto SecondOp = static_cast<Instruction::CastOps>(CastOpc);
4014  Type *SrcIntPtrTy =
4015  SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr;
4016  Type *MidIntPtrTy =
4017  MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr;
4018  Type *DstIntPtrTy =
4019  DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr;
4020  if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy,
4021  SrcIntPtrTy, MidIntPtrTy,
4022  DstIntPtrTy) == Instruction::BitCast)
4023  return Src;
4024  }
4025  }
4026 
4027  // bitcast x -> x
4028  if (CastOpc == Instruction::BitCast)
4029  if (Op->getType() == Ty)
4030  return Op;
4031 
4032  return nullptr;
4033 }
4034 
4035 Value *llvm::SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
4036  const SimplifyQuery &Q) {
4037  return ::SimplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit);
4038 }
4039 
4040 /// For the given destination element of a shuffle, peek through shuffles to
4041 /// match a root vector source operand that contains that element in the same
4042 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s).
4043 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1,
4044  int MaskVal, Value *RootVec,
4045  unsigned MaxRecurse) {
4046  if (!MaxRecurse--)
4047  return nullptr;
4048 
4049  // Bail out if any mask value is undefined. That kind of shuffle may be
4050  // simplified further based on demanded bits or other folds.
4051  if (MaskVal == -1)
4052  return nullptr;
4053 
4054  // The mask value chooses which source operand we need to look at next.
4055  int InVecNumElts = Op0->getType()->getVectorNumElements();
4056  int RootElt = MaskVal;
4057  Value *SourceOp = Op0;
4058  if (MaskVal >= InVecNumElts) {
4059  RootElt = MaskVal - InVecNumElts;
4060  SourceOp = Op1;
4061  }
4062 
4063  // If the source operand is a shuffle itself, look through it to find the
4064  // matching root vector.
4065  if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) {
4066  return foldIdentityShuffles(
4067  DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1),
4068  SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse);
4069  }
4070 
4071  // TODO: Look through bitcasts? What if the bitcast changes the vector element
4072  // size?
4073 
4074  // The source operand is not a shuffle. Initialize the root vector value for
4075  // this shuffle if that has not been done yet.
4076  if (!RootVec)
4077  RootVec = SourceOp;
4078 
4079  // Give up as soon as a source operand does not match the existing root value.
4080  if (RootVec != SourceOp)
4081  return nullptr;
4082 
4083  // The element must be coming from the same lane in the source vector
4084  // (although it may have crossed lanes in intermediate shuffles).
4085  if (RootElt != DestElt)
4086  return nullptr;
4087 
4088  return RootVec;
4089 }
4090 
4092  Type *RetTy, const SimplifyQuery &Q,
4093  unsigned MaxRecurse) {
4094  if (isa<UndefValue>(Mask))
4095  return UndefValue::get(RetTy);
4096 
4097  Type *InVecTy = Op0->getType();
4098  unsigned MaskNumElts = Mask->getType()->getVectorNumElements();
4099  unsigned InVecNumElts = InVecTy->getVectorNumElements();
4100 
4101  SmallVector<int, 32> Indices;
4102  ShuffleVectorInst::getShuffleMask(Mask, Indices);
4103  assert(MaskNumElts == Indices.size() &&
4104  "Size of Indices not same as number of mask elements?");
4105 
4106  // Canonicalization: If mask does not select elements from an input vector,
4107  // replace that input vector with undef.
4108  bool MaskSelects0 = false, MaskSelects1 = false;
4109  for (unsigned i = 0; i != MaskNumElts; ++i) {
4110  if (Indices[i] == -1)
4111  continue;
4112  if ((unsigned)Indices[i] < InVecNumElts)
4113  MaskSelects0 = true;
4114  else
4115  MaskSelects1 = true;
4116  }
4117  if (!MaskSelects0)
4118  Op0 = UndefValue::get(InVecTy);
4119  if (!MaskSelects1)
4120  Op1 = UndefValue::get(InVecTy);
4121 
4122  auto *Op0Const = dyn_cast<Constant>(Op0);
4123  auto *Op1Const = dyn_cast<Constant>(Op1);
4124 
4125  // If all operands are constant, constant fold the shuffle.
4126  if (Op0Const && Op1Const)
4127  return ConstantFoldShuffleVectorInstruction(Op0Const, Op1Const, Mask);
4128 
4129  // Canonicalization: if only one input vector is constant, it shall be the
4130  // second one.
4131  if (Op0Const && !Op1Const) {
4132  std::swap(Op0, Op1);
4133  ShuffleVectorInst::commuteShuffleMask(Indices, InVecNumElts);
4134  }
4135 
4136  // A shuffle of a splat is always the splat itself. Legal if the shuffle's
4137  // value type is same as the input vectors' type.
4138  if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0))
4139  if (isa<UndefValue>(Op1) && RetTy == InVecTy &&
4140  OpShuf->getMask()->getSplatValue())
4141  return Op0;
4142 
4143  // Don't fold a shuffle with undef mask elements. This may get folded in a
4144  // better way using demanded bits or other analysis.
4145  // TODO: Should we allow this?
4146  if (find(Indices, -1) != Indices.end())
4147  return nullptr;
4148 
4149  // Check if every element of this shuffle can be mapped back to the
4150  // corresponding element of a single root vector. If so, we don't need this
4151  // shuffle. This handles simple identity shuffles as well as chains of
4152  // shuffles that may widen/narrow and/or move elements across lanes and back.
4153  Value *RootVec = nullptr;
4154  for (unsigned i = 0; i != MaskNumElts; ++i) {
4155  // Note that recursion is limited for each vector element, so if any element
4156  // exceeds the limit, this will fail to simplify.
4157  RootVec =
4158  foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse);
4159 
4160  // We can't replace a widening/narrowing shuffle with one of its operands.
4161  if (!RootVec || RootVec->getType() != RetTy)
4162  return nullptr;
4163  }
4164  return RootVec;
4165 }
4166 
4167 /// Given operands for a ShuffleVectorInst, fold the result or return null.
4169  Type *RetTy, const SimplifyQuery &Q) {
4170  return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit);
4171 }
4172 
4173 /// Given operands for an FAdd, see if we can fold the result. If not, this
4174 /// returns null.
4176  const SimplifyQuery &Q, unsigned MaxRecurse) {
4177  if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q))
4178  return C;
4179 
4180  // fadd X, -0 ==> X
4181  if (match(Op1, m_NegZero()))
4182  return Op0;
4183 
4184  // fadd X, 0 ==> X, when we know X is not -0
4185  if (match(Op1, m_Zero()) &&
4186  (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
4187  return Op0;
4188 
4189  // fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
4190  // where nnan and ninf have to occur at least once somewhere in this
4191  // expression
4192  Value *SubOp = nullptr;
4193  if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0))))
4194  SubOp = Op1;
4195  else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1))))
4196  SubOp = Op0;
4197  if (SubOp) {
4198  Instruction *FSub = cast<Instruction>(SubOp);
4199  if ((FMF.noNaNs() || FSub->hasNoNaNs()) &&
4200  (FMF.noInfs() || FSub->hasNoInfs()))
4201  return Constant::getNullValue(Op0->getType());
4202  }
4203 
4204  return nullptr;
4205 }
4206 
4207 /// Given operands for an FSub, see if we can fold the result. If not, this
4208 /// returns null.
4210  const SimplifyQuery &Q, unsigned MaxRecurse) {
4211  if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q))
4212  return C;
4213 
4214  // fsub X, 0 ==> X
4215  if (match(Op1, m_Zero()))
4216  return Op0;
4217 
4218  // fsub X, -0 ==> X, when we know X is not -0
4219  if (match(Op1, m_NegZero()) &&
4220  (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
4221  return Op0;
4222 
4223  // fsub -0.0, (fsub -0.0, X) ==> X
4224  Value *X;
4225  if (match(Op0, m_NegZero()) && match(Op1, m_FSub(m_NegZero(), m_Value(X))))
4226  return X;
4227 
4228  // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.
4229  if (FMF.noSignedZeros() && match(Op0, m_AnyZero()) &&
4230  match(Op1, m_FSub(m_AnyZero(), m_Value(X))))
4231  return X;
4232 
4233  // fsub nnan x, x ==> 0.0
4234  if (FMF.noNaNs() && Op0 == Op1)
4235  return Constant::getNullValue(Op0->getType());
4236 
4237  return nullptr;
4238 }
4239 
4240 /// Given the operands for an FMul, see if we can fold the result
4242  const SimplifyQuery &Q, unsigned MaxRecurse) {
4243  if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q))
4244  return C;
4245 
4246  // fmul X, 1.0 ==> X
4247  if (match(Op1, m_FPOne()))
4248  return Op0;
4249 
4250  // fmul nnan nsz X, 0 ==> 0
4251  if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero()))
4252  return Op1;
4253 
4254  // sqrt(X) * sqrt(X) --> X
4255  Value *X;
4256  if (FMF.isFast() && Op0 == Op1 &&
4257  match(Op0, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))))
4258  return X;
4259 
4260  return nullptr;
4261 }
4262 
4264  const SimplifyQuery &Q) {
4265  return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit);
4266 }
4267 
4268 
4270  const SimplifyQuery &Q) {
4271  return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit);
4272 }
4273 
4275  const SimplifyQuery &Q) {
4276  return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit);
4277 }
4278 
4280  const SimplifyQuery &Q, unsigned) {
4281  if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q))
4282  return C;
4283 
4284  // undef / X -> undef (the undef could be a snan).
4285  if (match(Op0, m_Undef()))
4286  return Op0;
4287 
4288  // X / undef -> undef
4289  if (match(Op1, m_Undef()))
4290  return Op1;
4291 
4292  // X / 1.0 -> X
4293  if (match(Op1, m_FPOne()))
4294  return Op0;
4295 
4296  // 0 / X -> 0
4297  // Requires that NaNs are off (X could be zero) and signed zeroes are
4298  // ignored (X could be positive or negative, so the output sign is unknown).
4299  if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
4300  return Op0;
4301 
4302  if (FMF.noNaNs()) {
4303  // X / X -> 1.0 is legal when NaNs are ignored.
4304  // We can ignore infinities because INF/INF is NaN.
4305  if (Op0 == Op1)
4306  return ConstantFP::get(Op0->getType(), 1.0);
4307 
4308  // (X * Y) / Y --> X if we can reassociate to the above form.
4309  Value *X;
4310  if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1))))
4311  return X;
4312 
4313  // -X / X -> -1.0 and
4314  // X / -X -> -1.0 are legal when NaNs are ignored.
4315  // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored.
4316  if ((BinaryOperator::isFNeg(Op0, /*IgnoreZeroSign=*/true) &&
4317  BinaryOperator::getFNegArgument(Op0) == Op1) ||
4318  (BinaryOperator::isFNeg(Op1, /*IgnoreZeroSign=*/true) &&
4319  BinaryOperator::getFNegArgument(Op1) == Op0))
4320  return ConstantFP::get(Op0->getType(), -1.0);
4321  }
4322 
4323  return nullptr;
4324 }
4325 
4327  const SimplifyQuery &Q) {
4328  return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit);
4329 }
4330 
4332  const SimplifyQuery &Q, unsigned) {
4333  if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q))
4334  return C;
4335 
4336  // undef % X -> undef (the undef could be a snan).
4337  if (match(Op0, m_Undef()))
4338  return Op0;
4339 
4340  // X % undef -> undef
4341  if (match(Op1, m_Undef()))
4342  return Op1;
4343 
4344  // 0 % X -> 0
4345  // Requires that NaNs are off (X could be zero) and signed zeroes are
4346  // ignored (X could be positive or negative, so the output sign is unknown).
4347  if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
4348  return Op0;
4349 
4350  return nullptr;
4351 }
4352 
4354  const SimplifyQuery &Q) {
4355  return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit);
4356 }
4357 
4358 //=== Helper functions for higher up the class hierarchy.
4359 
4360 /// Given operands for a BinaryOperator, see if we can fold the result.
4361 /// If not, this returns null.
4362 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4363  const SimplifyQuery &Q, unsigned MaxRecurse) {
4364  switch (Opcode) {
4365  case Instruction::Add:
4366  return SimplifyAddInst(LHS, RHS, false, false, Q, MaxRecurse);
4367  case Instruction::Sub:
4368  return SimplifySubInst(LHS, RHS, false, false, Q, MaxRecurse);
4369  case Instruction::Mul:
4370  return SimplifyMulInst(LHS, RHS, Q, MaxRecurse);
4371  case Instruction::SDiv:
4372  return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
4373  case Instruction::UDiv:
4374  return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
4375  case Instruction::SRem:
4376  return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
4377  case Instruction::URem:
4378  return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
4379  case Instruction::Shl:
4380  return SimplifyShlInst(LHS, RHS, false, false, Q, MaxRecurse);
4381  case Instruction::LShr:
4382  return SimplifyLShrInst(LHS, RHS, false, Q, MaxRecurse);
4383  case Instruction::AShr:
4384  return SimplifyAShrInst(LHS, RHS, false, Q, MaxRecurse);
4385  case Instruction::And:
4386  return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
4387  case Instruction::Or:
4388  return SimplifyOrInst(LHS, RHS, Q, MaxRecurse);
4389  case Instruction::Xor:
4390  return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
4391  case Instruction::FAdd:
4392  return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4393  case Instruction::FSub:
4394  return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4395  case Instruction::FMul:
4396  return SimplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4397  case Instruction::FDiv:
4398  return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4399  case Instruction::FRem:
4400  return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4401  default:
4402  llvm_unreachable("Unexpected opcode");
4403  }
4404 }
4405 
4406 /// Given operands for a BinaryOperator, see if we can fold the result.
4407 /// If not, this returns null.
4408 /// In contrast to SimplifyBinOp, try to use FastMathFlag when folding the
4409 /// result. In case we don't need FastMathFlags, simply fall to SimplifyBinOp.
4410 static Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4411  const FastMathFlags &FMF, const SimplifyQuery &Q,
4412  unsigned MaxRecurse) {
4413  switch (Opcode) {
4414  case Instruction::FAdd:
4415  return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse);
4416  case Instruction::FSub:
4417  return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse);
4418  case Instruction::FMul:
4419  return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse);
4420  case Instruction::FDiv:
4421  return SimplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse);
4422  default:
4423  return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
4424  }
4425 }
4426 
4427 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4428  const SimplifyQuery &Q) {
4429  return ::SimplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit);
4430 }
4431 
4432 Value *llvm::SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4433  FastMathFlags FMF, const SimplifyQuery &Q) {
4434  return ::SimplifyFPBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit);
4435 }
4436 
4437 /// Given operands for a CmpInst, see if we can fold the result.
4438 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
4439  const SimplifyQuery &Q, unsigned MaxRecurse) {
4441  return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
4442  return SimplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4443 }
4444 
4445 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
4446  const SimplifyQuery &Q) {
4447  return ::SimplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
4448 }
4449 
4451  switch (ID) {
4452  default: return false;
4453 
4454  // Unary idempotent: f(f(x)) = f(x)
4455  case Intrinsic::fabs:
4456  case Intrinsic::floor:
4457  case Intrinsic::ceil:
4458  case Intrinsic::trunc:
4459  case Intrinsic::rint:
4460  case Intrinsic::nearbyint:
4461  case Intrinsic::round:
4462  case Intrinsic::canonicalize:
4463  return true;
4464  }
4465 }
4466 
4468  const DataLayout &DL) {
4469  GlobalValue *PtrSym;
4470  APInt PtrOffset;
4471  if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL))
4472  return nullptr;
4473 
4474  Type *Int8PtrTy = Type::getInt8PtrTy(Ptr->getContext());
4476  Type *Int32PtrTy = Int32Ty->getPointerTo();
4477  Type *Int64Ty = Type::getInt64Ty(Ptr->getContext());
4478 
4479  auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset);
4480  if (!OffsetConstInt || OffsetConstInt->getType()->getBitWidth() > 64)
4481  return nullptr;
4482 
4483  uint64_t OffsetInt = OffsetConstInt->getSExtValue();
4484  if (OffsetInt % 4 != 0)
4485  return nullptr;
4486 
4488  Int32Ty, ConstantExpr::getBitCast(Ptr, Int32PtrTy),
4489  ConstantInt::get(Int64Ty, OffsetInt / 4));
4490  Constant *Loaded = ConstantFoldLoadFromConstPtr(C, Int32Ty, DL);
4491  if (!Loaded)
4492  return nullptr;
4493 
4494  auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded);
4495  if (!LoadedCE)
4496  return nullptr;
4497 
4498  if (LoadedCE->getOpcode() == Instruction::Trunc) {
4499  LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
4500  if (!LoadedCE)
4501  return nullptr;
4502  }
4503 
4504  if (LoadedCE->getOpcode() != Instruction::Sub)
4505  return nullptr;
4506 
4507  auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
4508  if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt)
4509  return nullptr;
4510  auto *LoadedLHSPtr = LoadedLHS->getOperand(0);
4511 
4512  Constant *LoadedRHS = LoadedCE->getOperand(1);
4513  GlobalValue *LoadedRHSSym;
4514  APInt LoadedRHSOffset;
4515  if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset,
4516  DL) ||
4517  PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset)
4518  return nullptr;
4519 
4520  return ConstantExpr::getBitCast(LoadedLHSPtr, Int8PtrTy);
4521 }
4522 
4524  auto *ConstMask = dyn_cast<Constant>(Mask);
4525  if (!ConstMask)
4526  return false;
4527  if (ConstMask->isNullValue() || isa<UndefValue>(ConstMask))
4528  return true;
4529  for (unsigned I = 0, E = ConstMask->getType()->getVectorNumElements(); I != E;
4530  ++I) {
4531  if (auto *MaskElt = ConstMask->getAggregateElement(I))
4532  if (MaskElt->isNullValue() || isa<UndefValue>(MaskElt))
4533  continue;
4534  return false;
4535  }
4536  return true;
4537 }
4538 
4539 template <typename IterTy>
4540 static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
4541  const SimplifyQuery &Q, unsigned MaxRecurse) {
4542  Intrinsic::ID IID = F->getIntrinsicID();
4543  unsigned NumOperands = std::distance(ArgBegin, ArgEnd);
4544 
4545  // Unary Ops
4546  if (NumOperands == 1) {
4547  // Perform idempotent optimizations
4548  if (IsIdempotent(IID)) {
4549  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin)) {
4550  if (II->getIntrinsicID() == IID)
4551  return II;
4552  }
4553  }
4554 
4555  Value *IIOperand = *ArgBegin;
4556  Value *X;
4557  switch (IID) {
4558  case Intrinsic::fabs: {
4559  if (SignBitMustBeZero(IIOperand, Q.TLI))
4560  return IIOperand;
4561  return nullptr;
4562  }
4563  case Intrinsic::bswap: {
4564  // bswap(bswap(x)) -> x
4565  if (match(IIOperand, m_BSwap(m_Value(X))))
4566  return X;
4567  return nullptr;
4568  }
4569  case Intrinsic::bitreverse: {
4570  // bitreverse(bitreverse(x)) -> x
4571  if (match(IIOperand, m_BitReverse(m_Value(X))))
4572  return X;
4573  return nullptr;
4574  }
4575  case Intrinsic::exp: {
4576  // exp(log(x)) -> x
4577  if (Q.CxtI->hasAllowReassoc() &&
4578  match(IIOperand, m_Intrinsic<Intrinsic::log>(m_Value(X))))
4579  return X;
4580  return nullptr;
4581  }
4582  case Intrinsic::exp2: {
4583  // exp2(log2(x)) -> x
4584  if (Q.CxtI->hasAllowReassoc() &&
4585  match(IIOperand, m_Intrinsic<Intrinsic::log2>(m_Value(X))))
4586  return X;
4587  return nullptr;
4588  }
4589  case Intrinsic::log: {
4590  // log(exp(x)) -> x
4591  if (Q.CxtI->hasAllowReassoc() &&
4592  match(IIOperand, m_Intrinsic<Intrinsic::exp>(m_Value(X))))
4593  return X;
4594  return nullptr;
4595  }
4596  case Intrinsic::log2: {
4597  // log2(exp2(x)) -> x
4598  if (Q.CxtI->hasAllowReassoc() &&
4599  match(IIOperand, m_Intrinsic<Intrinsic::exp2>(m_Value(X)))) {
4600  return X;
4601  }
4602  return nullptr;
4603  }
4604  default:
4605  return nullptr;
4606  }
4607  }
4608 
4609  // Binary Ops
4610  if (NumOperands == 2) {
4611  Value *LHS = *ArgBegin;
4612  Value *RHS = *(ArgBegin + 1);
4613  Type *ReturnType = F->getReturnType();
4614 
4615  switch (IID) {
4616  case Intrinsic::usub_with_overflow:
4617  case Intrinsic::ssub_with_overflow: {
4618  // X - X -> { 0, false }
4619  if (LHS == RHS)
4620  return Constant::getNullValue(ReturnType);
4621 
4622  // X - undef -> undef
4623  // undef - X -> undef
4624  if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS))
4625  return UndefValue::get(ReturnType);
4626 
4627  return nullptr;
4628  }
4629  case Intrinsic::uadd_with_overflow:
4630  case Intrinsic::sadd_with_overflow: {
4631  // X + undef -> undef
4632  if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS))
4633  return UndefValue::get(ReturnType);
4634 
4635  return nullptr;
4636  }
4637  case Intrinsic::umul_with_overflow:
4638  case Intrinsic::smul_with_overflow: {
4639  // 0 * X -> { 0, false }
4640  // X * 0 -> { 0, false }
4641  if (match(LHS, m_Zero()) || match(RHS, m_Zero()))
4642  return Constant::getNullValue(ReturnType);
4643 
4644  // undef * X -> { 0, false }
4645  // X * undef -> { 0, false }
4646  if (match(LHS, m_Undef()) || match(RHS, m_Undef()))
4647  return Constant::getNullValue(ReturnType);
4648 
4649  return nullptr;
4650  }
4651  case Intrinsic::load_relative: {
4652  Constant *C0 = dyn_cast<Constant>(LHS);
4653  Constant *C1 = dyn_cast<Constant>(RHS);
4654  if (C0 && C1)
4655  return SimplifyRelativeLoad(C0, C1, Q.DL);
4656  return nullptr;
4657  }
4658  case Intrinsic::powi:
4659  if (ConstantInt *Power = dyn_cast<ConstantInt>(RHS)) {
4660  // powi(x, 0) -> 1.0
4661  if (Power->isZero())
4662  return ConstantFP::get(LHS->getType(), 1.0);
4663  // powi(x, 1) -> x
4664  if (Power->isOne())
4665  return LHS;
4666  }
4667  return nullptr;
4668  default:
4669  return nullptr;
4670  }
4671  }
4672 
4673  // Simplify calls to llvm.masked.load.*
4674  switch (IID) {
4675  case Intrinsic::masked_load: {
4676  Value *MaskArg = ArgBegin[2];
4677  Value *PassthruArg = ArgBegin[3];
4678  // If the mask is all zeros or undef, the "passthru" argument is the result.
4679  if (maskIsAllZeroOrUndef(MaskArg))
4680  return PassthruArg;
4681  return nullptr;
4682  }
4683  default:
4684  return nullptr;
4685  }
4686 }
4687 
4688 template <typename IterTy>
4689 static Value *SimplifyCall(ImmutableCallSite CS, Value *V, IterTy ArgBegin,
4690  IterTy ArgEnd, const SimplifyQuery &Q,
4691  unsigned MaxRecurse) {
4692  Type *Ty = V->getType();
4693  if (PointerType *PTy = dyn_cast<PointerType>(Ty))
4694  Ty = PTy->getElementType();
4695  FunctionType *FTy = cast<FunctionType>(Ty);
4696 
4697  // call undef -> undef
4698  // call null -> undef
4699  if (isa<UndefValue>(V) || isa<ConstantPointerNull>(V))
4700  return UndefValue::get(FTy->getReturnType());
4701 
4702  Function *F = dyn_cast<Function>(V);
4703  if (!F)
4704  return nullptr;
4705 
4706  if (F->isIntrinsic())
4707  if (Value *Ret = SimplifyIntrinsic(F, ArgBegin, ArgEnd, Q, MaxRecurse))
4708  return Ret;
4709 
4710  if (!canConstantFoldCallTo(CS, F))
4711  return nullptr;
4712 
4713  SmallVector<Constant *, 4> ConstantArgs;
4714  ConstantArgs.reserve(ArgEnd - ArgBegin);
4715  for (IterTy I = ArgBegin, E = ArgEnd; I != E; ++I) {
4716  Constant *C = dyn_cast<Constant>(*I);
4717  if (!C)
4718  return nullptr;
4719  ConstantArgs.push_back(C);
4720  }
4721 
4722  return ConstantFoldCall(CS, F, ConstantArgs, Q.TLI);
4723 }
4724 
4726  User::op_iterator ArgBegin, User::op_iterator ArgEnd,
4727  const SimplifyQuery &Q) {
4728  return ::SimplifyCall(CS, V, ArgBegin, ArgEnd, Q, RecursionLimit);
4729 }
4730 
4732  ArrayRef<Value *> Args, const SimplifyQuery &Q) {
4733  return ::SimplifyCall(CS, V, Args.begin(), Args.end(), Q, RecursionLimit);
4734 }
4735 
4737  CallSite CS(const_cast<Instruction*>(ICS.getInstruction()));
4739  Q, RecursionLimit);
4740 }
4741 
4742 /// See if we can compute a simplified version of this instruction.
4743 /// If not, this returns null.
4744 
4747  const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I);
4748  Value *Result;
4749 
4750  switch (I->getOpcode()) {
4751  default:
4752  Result = ConstantFoldInstruction(I, Q.DL, Q.TLI);
4753  break;
4754  case Instruction::FAdd:
4755  Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
4756  I->getFastMathFlags(), Q);
4757  break;
4758  case Instruction::Add:
4759  Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
4760  cast<BinaryOperator>(I)->hasNoSignedWrap(),
4761  cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4762  break;
4763  case Instruction::FSub:
4764  Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
4765  I->getFastMathFlags(), Q);
4766  break;
4767  case Instruction::Sub:
4768  Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
4769  cast<BinaryOperator>(I)->hasNoSignedWrap(),
4770  cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4771  break;
4772  case Instruction::FMul:
4773  Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1),
4774  I->getFastMathFlags(), Q);
4775  break;
4776  case Instruction::Mul:
4777  Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), Q);
4778  break;
4779  case Instruction::SDiv:
4780  Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), Q);
4781  break;
4782  case Instruction::UDiv:
4783  Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), Q);
4784  break;
4785  case Instruction::FDiv:
4786  Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1),
4787  I->getFastMathFlags(), Q);
4788  break;
4789  case Instruction::SRem:
4790  Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), Q);
4791  break;
4792  case Instruction::URem:
4793  Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), Q);
4794  break;
4795  case Instruction::FRem:
4796  Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1),
4797  I->getFastMathFlags(), Q);
4798  break;
4799  case Instruction::Shl:
4800  Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
4801  cast<BinaryOperator>(I)->hasNoSignedWrap(),
4802  cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4803  break;
4804  case Instruction::LShr:
4805  Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
4806  cast<BinaryOperator>(I)->isExact(), Q);
4807  break;
4808  case Instruction::AShr:
4809  Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
4810  cast<BinaryOperator>(I)->isExact(), Q);
4811  break;
4812  case Instruction::And:
4813  Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), Q);
4814  break;
4815  case Instruction::Or:
4816  Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), Q);
4817  break;
4818  case Instruction::Xor:
4819  Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), Q);
4820  break;
4821  case Instruction::ICmp:
4822  Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
4823  I->getOperand(0), I->getOperand(1), Q);
4824  break;
4825  case Instruction::FCmp:
4826  Result =
4827  SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0),
4828  I->getOperand(1), I->getFastMathFlags(), Q);
4829  break;
4830  case Instruction::Select:
4831  Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
4832  I->getOperand(2), Q);
4833  break;
4834  case Instruction::GetElementPtr: {
4835  SmallVector<Value *, 8> Ops(I->op_begin(), I->op_end());
4836  Result = SimplifyGEPInst(cast<GetElementPtrInst>(I)->getSourceElementType(),
4837  Ops, Q);
4838  break;
4839  }
4840  case Instruction::InsertValue: {
4841  InsertValueInst *IV = cast<InsertValueInst>(I);
4844  IV->getIndices(), Q);
4845  break;
4846  }
4847  case Instruction::InsertElement: {
4848  auto *IE = cast<InsertElementInst>(I);
4849  Result = SimplifyInsertElementInst(IE->getOperand(0), IE->getOperand(1),
4850  IE->getOperand(2), Q);
4851  break;
4852  }
4853  case Instruction::ExtractValue: {
4854  auto *EVI = cast<ExtractValueInst>(I);
4855  Result = SimplifyExtractValueInst(EVI->getAggregateOperand(),
4856  EVI->getIndices(), Q);
4857  break;
4858  }
4859  case Instruction::ExtractElement: {
4860  auto *EEI = cast<ExtractElementInst>(I);
4861  Result = SimplifyExtractElementInst(EEI->getVectorOperand(),
4862  EEI->getIndexOperand(), Q);
4863  break;
4864  }
4865  case Instruction::ShuffleVector: {
4866  auto *SVI = cast<ShuffleVectorInst>(I);
4867  Result = SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
4868  SVI->getMask(), SVI->getType(), Q);
4869  break;
4870  }
4871  case Instruction::PHI:
4872  Result = SimplifyPHINode(cast<PHINode>(I), Q);
4873  break;
4874  case Instruction::Call: {
4875  CallSite CS(cast<CallInst>(I));
4876  Result = SimplifyCall(CS, Q);
4877  break;
4878  }
4879 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc:
4880 #include "llvm/IR/Instruction.def"
4881 #undef HANDLE_CAST_INST
4882  Result =
4883  SimplifyCastInst(I->getOpcode(), I->getOperand(0), I->getType(), Q);
4884  break;
4885  case Instruction::Alloca:
4886  // No simplifications for Alloca and it can't be constant folded.
4887  Result = nullptr;
4888  break;
4889  }
4890 
4891  // In general, it is possible for computeKnownBits to determine all bits in a
4892  // value even when the operands are not all constants.
4893  if (!Result && I->getType()->isIntOrIntVectorTy()) {
4894  KnownBits Known = computeKnownBits(I, Q.DL, /*Depth*/ 0, Q.AC, I, Q.DT, ORE);
4895  if (Known.isConstant())