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);
66  unsigned);
67 
68 /// For a boolean type or a vector of boolean type, return false or a vector
69 /// with every element false.
70 static Constant *getFalse(Type *Ty) {
71  return ConstantInt::getFalse(Ty);
72 }
73 
74 /// For a boolean type or a vector of boolean type, return true or a vector
75 /// with every element true.
76 static Constant *getTrue(Type *Ty) {
77  return ConstantInt::getTrue(Ty);
78 }
79 
80 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
81 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
82  Value *RHS) {
83  CmpInst *Cmp = dyn_cast<CmpInst>(V);
84  if (!Cmp)
85  return false;
86  CmpInst::Predicate CPred = Cmp->getPredicate();
87  Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
88  if (CPred == Pred && CLHS == LHS && CRHS == RHS)
89  return true;
90  return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
91  CRHS == LHS;
92 }
93 
94 /// Does the given value dominate the specified phi node?
95 static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
97  if (!I)
98  // Arguments and constants dominate all instructions.
99  return true;
100 
101  // If we are processing instructions (and/or basic blocks) that have not been
102  // fully added to a function, the parent nodes may still be null. Simply
103  // return the conservative answer in these cases.
104  if (!I->getParent() || !P->getParent() || !I->getFunction())
105  return false;
106 
107  // If we have a DominatorTree then do a precise test.
108  if (DT)
109  return DT->dominates(I, P);
110 
111  // Otherwise, if the instruction is in the entry block and is not an invoke,
112  // then it obviously dominates all phi nodes.
113  if (I->getParent() == &I->getFunction()->getEntryBlock() &&
114  !isa<InvokeInst>(I))
115  return true;
116 
117  return false;
118 }
119 
120 /// Simplify "A op (B op' C)" by distributing op over op', turning it into
121 /// "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
122 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
123 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
124 /// Returns the simplified value, or null if no simplification was performed.
126  Instruction::BinaryOps OpcodeToExpand,
127  const SimplifyQuery &Q, unsigned MaxRecurse) {
128  // Recursion is always used, so bail out at once if we already hit the limit.
129  if (!MaxRecurse--)
130  return nullptr;
131 
132  // Check whether the expression has the form "(A op' B) op C".
133  if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
134  if (Op0->getOpcode() == OpcodeToExpand) {
135  // It does! Try turning it into "(A op C) op' (B op C)".
136  Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
137  // Do "A op C" and "B op C" both simplify?
138  if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
139  if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
140  // They do! Return "L op' R" if it simplifies or is already available.
141  // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
142  if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
143  && L == B && R == A)) {
144  ++NumExpand;
145  return LHS;
146  }
147  // Otherwise return "L op' R" if it simplifies.
148  if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
149  ++NumExpand;
150  return V;
151  }
152  }
153  }
154 
155  // Check whether the expression has the form "A op (B op' C)".
156  if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
157  if (Op1->getOpcode() == OpcodeToExpand) {
158  // It does! Try turning it into "(A op B) op' (A op C)".
159  Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
160  // Do "A op B" and "A op C" both simplify?
161  if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
162  if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
163  // They do! Return "L op' R" if it simplifies or is already available.
164  // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
165  if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
166  && L == C && R == B)) {
167  ++NumExpand;
168  return RHS;
169  }
170  // Otherwise return "L op' R" if it simplifies.
171  if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
172  ++NumExpand;
173  return V;
174  }
175  }
176  }
177 
178  return nullptr;
179 }
180 
181 /// Generic simplifications for associative binary operations.
182 /// Returns the simpler value, or null if none was found.
184  Value *LHS, Value *RHS,
185  const SimplifyQuery &Q,
186  unsigned MaxRecurse) {
187  assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
188 
189  // Recursion is always used, so bail out at once if we already hit the limit.
190  if (!MaxRecurse--)
191  return nullptr;
192 
195 
196  // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
197  if (Op0 && Op0->getOpcode() == Opcode) {
198  Value *A = Op0->getOperand(0);
199  Value *B = Op0->getOperand(1);
200  Value *C = RHS;
201 
202  // Does "B op C" simplify?
203  if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
204  // It does! Return "A op V" if it simplifies or is already available.
205  // If V equals B then "A op V" is just the LHS.
206  if (V == B) return LHS;
207  // Otherwise return "A op V" if it simplifies.
208  if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
209  ++NumReassoc;
210  return W;
211  }
212  }
213  }
214 
215  // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
216  if (Op1 && Op1->getOpcode() == Opcode) {
217  Value *A = LHS;
218  Value *B = Op1->getOperand(0);
219  Value *C = Op1->getOperand(1);
220 
221  // Does "A op B" simplify?
222  if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
223  // It does! Return "V op C" if it simplifies or is already available.
224  // If V equals B then "V op C" is just the RHS.
225  if (V == B) return RHS;
226  // Otherwise return "V op C" if it simplifies.
227  if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
228  ++NumReassoc;
229  return W;
230  }
231  }
232  }
233 
234  // The remaining transforms require commutativity as well as associativity.
235  if (!Instruction::isCommutative(Opcode))
236  return nullptr;
237 
238  // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
239  if (Op0 && Op0->getOpcode() == Opcode) {
240  Value *A = Op0->getOperand(0);
241  Value *B = Op0->getOperand(1);
242  Value *C = RHS;
243 
244  // Does "C op A" simplify?
245  if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
246  // It does! Return "V op B" if it simplifies or is already available.
247  // If V equals A then "V op B" is just the LHS.
248  if (V == A) return LHS;
249  // Otherwise return "V op B" if it simplifies.
250  if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
251  ++NumReassoc;
252  return W;
253  }
254  }
255  }
256 
257  // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
258  if (Op1 && Op1->getOpcode() == Opcode) {
259  Value *A = LHS;
260  Value *B = Op1->getOperand(0);
261  Value *C = Op1->getOperand(1);
262 
263  // Does "C op A" simplify?
264  if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
265  // It does! Return "B op V" if it simplifies or is already available.
266  // If V equals C then "B op V" is just the RHS.
267  if (V == C) return RHS;
268  // Otherwise return "B op V" if it simplifies.
269  if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
270  ++NumReassoc;
271  return W;
272  }
273  }
274  }
275 
276  return nullptr;
277 }
278 
279 /// In the case of a binary operation with a select instruction as an operand,
280 /// try to simplify the binop by seeing whether evaluating it on both branches
281 /// of the select results in the same value. Returns the common value if so,
282 /// otherwise returns null.
284  Value *RHS, const SimplifyQuery &Q,
285  unsigned MaxRecurse) {
286  // Recursion is always used, so bail out at once if we already hit the limit.
287  if (!MaxRecurse--)
288  return nullptr;
289 
290  SelectInst *SI;
291  if (isa<SelectInst>(LHS)) {
292  SI = cast<SelectInst>(LHS);
293  } else {
294  assert(isa<SelectInst>(RHS) && "No select instruction operand!");
295  SI = cast<SelectInst>(RHS);
296  }
297 
298  // Evaluate the BinOp on the true and false branches of the select.
299  Value *TV;
300  Value *FV;
301  if (SI == LHS) {
302  TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
303  FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
304  } else {
305  TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
306  FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
307  }
308 
309  // If they simplified to the same value, then return the common value.
310  // If they both failed to simplify then return null.
311  if (TV == FV)
312  return TV;
313 
314  // If one branch simplified to undef, return the other one.
315  if (TV && isa<UndefValue>(TV))
316  return FV;
317  if (FV && isa<UndefValue>(FV))
318  return TV;
319 
320  // If applying the operation did not change the true and false select values,
321  // then the result of the binop is the select itself.
322  if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
323  return SI;
324 
325  // If one branch simplified and the other did not, and the simplified
326  // value is equal to the unsimplified one, return the simplified value.
327  // For example, select (cond, X, X & Z) & Z -> X & Z.
328  if ((FV && !TV) || (TV && !FV)) {
329  // Check that the simplified value has the form "X op Y" where "op" is the
330  // same as the original operation.
331  Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
332  if (Simplified && Simplified->getOpcode() == unsigned(Opcode)) {
333  // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
334  // We already know that "op" is the same as for the simplified value. See
335  // if the operands match too. If so, return the simplified value.
336  Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
337  Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
338  Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
339  if (Simplified->getOperand(0) == UnsimplifiedLHS &&
340  Simplified->getOperand(1) == UnsimplifiedRHS)
341  return Simplified;
342  if (Simplified->isCommutative() &&
343  Simplified->getOperand(1) == UnsimplifiedLHS &&
344  Simplified->getOperand(0) == UnsimplifiedRHS)
345  return Simplified;
346  }
347  }
348 
349  return nullptr;
350 }
351 
352 /// In the case of a comparison with a select instruction, try to simplify the
353 /// comparison by seeing whether both branches of the select result in the same
354 /// value. Returns the common value if so, otherwise returns null.
356  Value *RHS, const SimplifyQuery &Q,
357  unsigned MaxRecurse) {
358  // Recursion is always used, so bail out at once if we already hit the limit.
359  if (!MaxRecurse--)
360  return nullptr;
361 
362  // Make sure the select is on the LHS.
363  if (!isa<SelectInst>(LHS)) {
364  std::swap(LHS, RHS);
365  Pred = CmpInst::getSwappedPredicate(Pred);
366  }
367  assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
368  SelectInst *SI = cast<SelectInst>(LHS);
369  Value *Cond = SI->getCondition();
370  Value *TV = SI->getTrueValue();
371  Value *FV = SI->getFalseValue();
372 
373  // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
374  // Does "cmp TV, RHS" simplify?
375  Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
376  if (TCmp == Cond) {
377  // It not only simplified, it simplified to the select condition. Replace
378  // it with 'true'.
379  TCmp = getTrue(Cond->getType());
380  } else if (!TCmp) {
381  // It didn't simplify. However if "cmp TV, RHS" is equal to the select
382  // condition then we can replace it with 'true'. Otherwise give up.
383  if (!isSameCompare(Cond, Pred, TV, RHS))
384  return nullptr;
385  TCmp = getTrue(Cond->getType());
386  }
387 
388  // Does "cmp FV, RHS" simplify?
389  Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
390  if (FCmp == Cond) {
391  // It not only simplified, it simplified to the select condition. Replace
392  // it with 'false'.
393  FCmp = getFalse(Cond->getType());
394  } else if (!FCmp) {
395  // It didn't simplify. However if "cmp FV, RHS" is equal to the select
396  // condition then we can replace it with 'false'. Otherwise give up.
397  if (!isSameCompare(Cond, Pred, FV, RHS))
398  return nullptr;
399  FCmp = getFalse(Cond->getType());
400  }
401 
402  // If both sides simplified to the same value, then use it as the result of
403  // the original comparison.
404  if (TCmp == FCmp)
405  return TCmp;
406 
407  // The remaining cases only make sense if the select condition has the same
408  // type as the result of the comparison, so bail out if this is not so.
409  if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
410  return nullptr;
411  // If the false value simplified to false, then the result of the compare
412  // is equal to "Cond && TCmp". This also catches the case when the false
413  // value simplified to false and the true value to true, returning "Cond".
414  if (match(FCmp, m_Zero()))
415  if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
416  return V;
417  // If the true value simplified to true, then the result of the compare
418  // is equal to "Cond || FCmp".
419  if (match(TCmp, m_One()))
420  if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
421  return V;
422  // Finally, if the false value simplified to true and the true value to
423  // false, then the result of the compare is equal to "!Cond".
424  if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
425  if (Value *V =
426  SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
427  Q, MaxRecurse))
428  return V;
429 
430  return nullptr;
431 }
432 
433 /// In the case of a binary operation with an operand that is a PHI instruction,
434 /// try to simplify the binop by seeing whether evaluating it on the incoming
435 /// phi values yields the same result for every value. If so returns the common
436 /// value, otherwise returns null.
438  Value *RHS, const SimplifyQuery &Q,
439  unsigned MaxRecurse) {
440  // Recursion is always used, so bail out at once if we already hit the limit.
441  if (!MaxRecurse--)
442  return nullptr;
443 
444  PHINode *PI;
445  if (isa<PHINode>(LHS)) {
446  PI = cast<PHINode>(LHS);
447  // Bail out if RHS and the phi may be mutually interdependent due to a loop.
448  if (!valueDominatesPHI(RHS, PI, Q.DT))
449  return nullptr;
450  } else {
451  assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
452  PI = cast<PHINode>(RHS);
453  // Bail out if LHS and the phi may be mutually interdependent due to a loop.
454  if (!valueDominatesPHI(LHS, PI, Q.DT))
455  return nullptr;
456  }
457 
458  // Evaluate the BinOp on the incoming phi values.
459  Value *CommonValue = nullptr;
460  for (Value *Incoming : PI->incoming_values()) {
461  // If the incoming value is the phi node itself, it can safely be skipped.
462  if (Incoming == PI) continue;
463  Value *V = PI == LHS ?
464  SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
465  SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
466  // If the operation failed to simplify, or simplified to a different value
467  // to previously, then give up.
468  if (!V || (CommonValue && V != CommonValue))
469  return nullptr;
470  CommonValue = V;
471  }
472 
473  return CommonValue;
474 }
475 
476 /// In the case of a comparison with a PHI instruction, try to simplify the
477 /// comparison by seeing whether comparing with all of the incoming phi values
478 /// yields the same result every time. If so returns the common result,
479 /// otherwise returns null.
481  const SimplifyQuery &Q, unsigned MaxRecurse) {
482  // Recursion is always used, so bail out at once if we already hit the limit.
483  if (!MaxRecurse--)
484  return nullptr;
485 
486  // Make sure the phi is on the LHS.
487  if (!isa<PHINode>(LHS)) {
488  std::swap(LHS, RHS);
489  Pred = CmpInst::getSwappedPredicate(Pred);
490  }
491  assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
492  PHINode *PI = cast<PHINode>(LHS);
493 
494  // Bail out if RHS and the phi may be mutually interdependent due to a loop.
495  if (!valueDominatesPHI(RHS, PI, Q.DT))
496  return nullptr;
497 
498  // Evaluate the BinOp on the incoming phi values.
499  Value *CommonValue = nullptr;
500  for (Value *Incoming : PI->incoming_values()) {
501  // If the incoming value is the phi node itself, it can safely be skipped.
502  if (Incoming == PI) continue;
503  Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
504  // If the operation failed to simplify, or simplified to a different value
505  // to previously, then give up.
506  if (!V || (CommonValue && V != CommonValue))
507  return nullptr;
508  CommonValue = V;
509  }
510 
511  return CommonValue;
512 }
513 
515  Value *&Op0, Value *&Op1,
516  const SimplifyQuery &Q) {
517  if (auto *CLHS = dyn_cast<Constant>(Op0)) {
518  if (auto *CRHS = dyn_cast<Constant>(Op1))
519  return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL);
520 
521  // Canonicalize the constant to the RHS if this is a commutative operation.
522  if (Instruction::isCommutative(Opcode))
523  std::swap(Op0, Op1);
524  }
525  return nullptr;
526 }
527 
528 /// Given operands for an Add, see if we can fold the result.
529 /// If not, this returns null.
530 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
531  const SimplifyQuery &Q, unsigned MaxRecurse) {
532  if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q))
533  return C;
534 
535  // X + undef -> undef
536  if (match(Op1, m_Undef()))
537  return Op1;
538 
539  // X + 0 -> X
540  if (match(Op1, m_Zero()))
541  return Op0;
542 
543  // X + (Y - X) -> Y
544  // (Y - X) + X -> Y
545  // Eg: X + -X -> 0
546  Value *Y = nullptr;
547  if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
548  match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
549  return Y;
550 
551  // X + ~X -> -1 since ~X = -X-1
552  Type *Ty = Op0->getType();
553  if (match(Op0, m_Not(m_Specific(Op1))) ||
554  match(Op1, m_Not(m_Specific(Op0))))
555  return Constant::getAllOnesValue(Ty);
556 
557  // add nsw/nuw (xor Y, signmask), signmask --> Y
558  // The no-wrapping add guarantees that the top bit will be set by the add.
559  // Therefore, the xor must be clearing the already set sign bit of Y.
560  if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) &&
561  match(Op0, m_Xor(m_Value(Y), m_SignMask())))
562  return Y;
563 
564  // add nuw %x, -1 -> -1, because %x can only be 0.
565  if (IsNUW && match(Op1, m_AllOnes()))
566  return Op1; // Which is -1.
567 
568  /// i1 add -> xor.
569  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
570  if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
571  return V;
572 
573  // Try some generic simplifications for associative operations.
574  if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
575  MaxRecurse))
576  return V;
577 
578  // Threading Add over selects and phi nodes is pointless, so don't bother.
579  // Threading over the select in "A + select(cond, B, C)" means evaluating
580  // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
581  // only if B and C are equal. If B and C are equal then (since we assume
582  // that operands have already been simplified) "select(cond, B, C)" should
583  // have been simplified to the common value of B and C already. Analysing
584  // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
585  // for threading over phi nodes.
586 
587  return nullptr;
588 }
589 
590 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
591  const SimplifyQuery &Query) {
592  return ::SimplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit);
593 }
594 
595 /// Compute the base pointer and cumulative constant offsets for V.
596 ///
597 /// This strips all constant offsets off of V, leaving it the base pointer, and
598 /// accumulates the total constant offset applied in the returned constant. It
599 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
600 /// no constant offsets applied.
601 ///
602 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
603 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
604 /// folding.
606  bool AllowNonInbounds = false) {
608 
609  Type *IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType();
610  APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
611 
612  // Even though we don't look through PHI nodes, we could be called on an
613  // instruction in an unreachable block, which may be on a cycle.
614  SmallPtrSet<Value *, 4> Visited;
615  Visited.insert(V);
616  do {
617  if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
618  if ((!AllowNonInbounds && !GEP->isInBounds()) ||
619  !GEP->accumulateConstantOffset(DL, Offset))
620  break;
621  V = GEP->getPointerOperand();
622  } else if (Operator::getOpcode(V) == Instruction::BitCast) {
623  V = cast<Operator>(V)->getOperand(0);
624  } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
625  if (GA->isInterposable())
626  break;
627  V = GA->getAliasee();
628  } else {
629  if (auto CS = CallSite(V))
630  if (Value *RV = CS.getReturnedArgOperand()) {
631  V = RV;
632  continue;
633  }
634  break;
635  }
636  assert(V->getType()->isPtrOrPtrVectorTy() && "Unexpected operand type!");
637  } while (Visited.insert(V).second);
638 
639  Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
640  if (V->getType()->isVectorTy())
642  OffsetIntPtr);
643  return OffsetIntPtr;
644 }
645 
646 /// Compute the constant difference between two pointer values.
647 /// If the difference is not a constant, returns zero.
649  Value *RHS) {
650  Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
651  Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
652 
653  // If LHS and RHS are not related via constant offsets to the same base
654  // value, there is nothing we can do here.
655  if (LHS != RHS)
656  return nullptr;
657 
658  // Otherwise, the difference of LHS - RHS can be computed as:
659  // LHS - RHS
660  // = (LHSOffset + Base) - (RHSOffset + Base)
661  // = LHSOffset - RHSOffset
662  return ConstantExpr::getSub(LHSOffset, RHSOffset);
663 }
664 
665 /// Given operands for a Sub, see if we can fold the result.
666 /// If not, this returns null.
667 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
668  const SimplifyQuery &Q, unsigned MaxRecurse) {
669  if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q))
670  return C;
671 
672  // X - undef -> undef
673  // undef - X -> undef
674  if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
675  return UndefValue::get(Op0->getType());
676 
677  // X - 0 -> X
678  if (match(Op1, m_Zero()))
679  return Op0;
680 
681  // X - X -> 0
682  if (Op0 == Op1)
683  return Constant::getNullValue(Op0->getType());
684 
685  // Is this a negation?
686  if (match(Op0, m_Zero())) {
687  // 0 - X -> 0 if the sub is NUW.
688  if (isNUW)
689  return Constant::getNullValue(Op0->getType());
690 
691  KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
692  if (Known.Zero.isMaxSignedValue()) {
693  // Op1 is either 0 or the minimum signed value. If the sub is NSW, then
694  // Op1 must be 0 because negating the minimum signed value is undefined.
695  if (isNSW)
696  return Constant::getNullValue(Op0->getType());
697 
698  // 0 - X -> X if X is 0 or the minimum signed value.
699  return Op1;
700  }
701  }
702 
703  // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
704  // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
705  Value *X = nullptr, *Y = nullptr, *Z = Op1;
706  if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
707  // See if "V === Y - Z" simplifies.
708  if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
709  // It does! Now see if "X + V" simplifies.
710  if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
711  // It does, we successfully reassociated!
712  ++NumReassoc;
713  return W;
714  }
715  // See if "V === X - Z" simplifies.
716  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
717  // It does! Now see if "Y + V" simplifies.
718  if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
719  // It does, we successfully reassociated!
720  ++NumReassoc;
721  return W;
722  }
723  }
724 
725  // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
726  // For example, X - (X + 1) -> -1
727  X = Op0;
728  if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
729  // See if "V === X - Y" simplifies.
730  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
731  // It does! Now see if "V - Z" simplifies.
732  if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
733  // It does, we successfully reassociated!
734  ++NumReassoc;
735  return W;
736  }
737  // See if "V === X - Z" simplifies.
738  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
739  // It does! Now see if "V - Y" simplifies.
740  if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
741  // It does, we successfully reassociated!
742  ++NumReassoc;
743  return W;
744  }
745  }
746 
747  // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
748  // For example, X - (X - Y) -> Y.
749  Z = Op0;
750  if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
751  // See if "V === Z - X" simplifies.
752  if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
753  // It does! Now see if "V + Y" simplifies.
754  if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
755  // It does, we successfully reassociated!
756  ++NumReassoc;
757  return W;
758  }
759 
760  // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
761  if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
762  match(Op1, m_Trunc(m_Value(Y))))
763  if (X->getType() == Y->getType())
764  // See if "V === X - Y" simplifies.
765  if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
766  // It does! Now see if "trunc V" simplifies.
767  if (Value *W = SimplifyCastInst(Instruction::Trunc, V, Op0->getType(),
768  Q, MaxRecurse - 1))
769  // It does, return the simplified "trunc V".
770  return W;
771 
772  // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
773  if (match(Op0, m_PtrToInt(m_Value(X))) &&
774  match(Op1, m_PtrToInt(m_Value(Y))))
775  if (Constant *Result = computePointerDifference(Q.DL, X, Y))
776  return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
777 
778  // i1 sub -> xor.
779  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
780  if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
781  return V;
782 
783  // Threading Sub over selects and phi nodes is pointless, so don't bother.
784  // Threading over the select in "A - select(cond, B, C)" means evaluating
785  // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
786  // only if B and C are equal. If B and C are equal then (since we assume
787  // that operands have already been simplified) "select(cond, B, C)" should
788  // have been simplified to the common value of B and C already. Analysing
789  // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
790  // for threading over phi nodes.
791 
792  return nullptr;
793 }
794 
795 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
796  const SimplifyQuery &Q) {
797  return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
798 }
799 
800 /// Given operands for a Mul, see if we can fold the result.
801 /// If not, this returns null.
802 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
803  unsigned MaxRecurse) {
804  if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q))
805  return C;
806 
807  // X * undef -> 0
808  // X * 0 -> 0
809  if (match(Op1, m_CombineOr(m_Undef(), m_Zero())))
810  return Constant::getNullValue(Op0->getType());
811 
812  // X * 1 -> X
813  if (match(Op1, m_One()))
814  return Op0;
815 
816  // (X / Y) * Y -> X if the division is exact.
817  Value *X = nullptr;
818  if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
819  match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
820  return X;
821 
822  // i1 mul -> and.
823  if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
824  if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
825  return V;
826 
827  // Try some generic simplifications for associative operations.
828  if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
829  MaxRecurse))
830  return V;
831 
832  // Mul distributes over Add. Try some generic simplifications based on this.
833  if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
834  Q, MaxRecurse))
835  return V;
836 
837  // If the operation is with the result of a select instruction, check whether
838  // operating on either branch of the select always yields the same value.
839  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
840  if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
841  MaxRecurse))
842  return V;
843 
844  // If the operation is with the result of a phi instruction, check whether
845  // operating on all incoming values of the phi always yields the same value.
846  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
847  if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
848  MaxRecurse))
849  return V;
850 
851  return nullptr;
852 }
853 
856 }
857 
858 /// Check for common or similar folds of integer division or integer remainder.
859 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem).
860 static Value *simplifyDivRem(Value *Op0, Value *Op1, bool IsDiv) {
861  Type *Ty = Op0->getType();
862 
863  // X / undef -> undef
864  // X % undef -> undef
865  if (match(Op1, m_Undef()))
866  return Op1;
867 
868  // X / 0 -> undef
869  // X % 0 -> undef
870  // We don't need to preserve faults!
871  if (match(Op1, m_Zero()))
872  return UndefValue::get(Ty);
873 
874  // If any element of a constant divisor vector is zero or undef, the whole op
875  // is undef.
876  auto *Op1C = dyn_cast<Constant>(Op1);
877  if (Op1C && Ty->isVectorTy()) {
878  unsigned NumElts = Ty->getVectorNumElements();
879  for (unsigned i = 0; i != NumElts; ++i) {
880  Constant *Elt = Op1C->getAggregateElement(i);
881  if (Elt && (Elt->isNullValue() || isa<UndefValue>(Elt)))
882  return UndefValue::get(Ty);
883  }
884  }
885 
886  // undef / X -> 0
887  // undef % X -> 0
888  if (match(Op0, m_Undef()))
889  return Constant::getNullValue(Ty);
890 
891  // 0 / X -> 0
892  // 0 % X -> 0
893  if (match(Op0, m_Zero()))
894  return Constant::getNullValue(Op0->getType());
895 
896  // X / X -> 1
897  // X % X -> 0
898  if (Op0 == Op1)
899  return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty);
900 
901  // X / 1 -> X
902  // X % 1 -> 0
903  // If this is a boolean op (single-bit element type), we can't have
904  // division-by-zero or remainder-by-zero, so assume the divisor is 1.
905  if (match(Op1, m_One()) || Ty->isIntOrIntVectorTy(1))
906  return IsDiv ? Op0 : Constant::getNullValue(Ty);
907 
908  return nullptr;
909 }
910 
911 /// Given a predicate and two operands, return true if the comparison is true.
912 /// This is a helper for div/rem simplification where we return some other value
913 /// when we can prove a relationship between the operands.
914 static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS,
915  const SimplifyQuery &Q, unsigned MaxRecurse) {
916  Value *V = SimplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse);
917  Constant *C = dyn_cast_or_null<Constant>(V);
918  return (C && C->isAllOnesValue());
919 }
920 
921 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer
922 /// to simplify X % Y to X.
923 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q,
924  unsigned MaxRecurse, bool IsSigned) {
925  // Recursion is always used, so bail out at once if we already hit the limit.
926  if (!MaxRecurse--)
927  return false;
928 
929  if (IsSigned) {
930  // |X| / |Y| --> 0
931  //
932  // We require that 1 operand is a simple constant. That could be extended to
933  // 2 variables if we computed the sign bit for each.
934  //
935  // Make sure that a constant is not the minimum signed value because taking
936  // the abs() of that is undefined.
937  Type *Ty = X->getType();
938  const APInt *C;
939  if (match(X, m_APInt(C)) && !C->isMinSignedValue()) {
940  // Is the variable divisor magnitude always greater than the constant
941  // dividend magnitude?
942  // |Y| > |C| --> Y < -abs(C) or Y > abs(C)
943  Constant *PosDividendC = ConstantInt::get(Ty, C->abs());
944  Constant *NegDividendC = ConstantInt::get(Ty, -C->abs());
945  if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) ||
946  isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse))
947  return true;
948  }
949  if (match(Y, m_APInt(C))) {
950  // Special-case: we can't take the abs() of a minimum signed value. If
951  // that's the divisor, then all we have to do is prove that the dividend
952  // is also not the minimum signed value.
953  if (C->isMinSignedValue())
954  return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse);
955 
956  // Is the variable dividend magnitude always less than the constant
957  // divisor magnitude?
958  // |X| < |C| --> X > -abs(C) and X < abs(C)
959  Constant *PosDivisorC = ConstantInt::get(Ty, C->abs());
960  Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs());
961  if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) &&
962  isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse))
963  return true;
964  }
965  return false;
966  }
967 
968  // IsSigned == false.
969  // Is the dividend unsigned less than the divisor?
970  return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse);
971 }
972 
973 /// These are simplifications common to SDiv and UDiv.
975  const SimplifyQuery &Q, unsigned MaxRecurse) {
976  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
977  return C;
978 
979  if (Value *V = simplifyDivRem(Op0, Op1, true))
980  return V;
981 
982  bool IsSigned = Opcode == Instruction::SDiv;
983 
984  // (X * Y) / Y -> X if the multiplication does not overflow.
985  Value *X;
986  if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) {
987  auto *Mul = cast<OverflowingBinaryOperator>(Op0);
988  // If the Mul does not overflow, then we are good to go.
989  if ((IsSigned && Mul->hasNoSignedWrap()) ||
990  (!IsSigned && Mul->hasNoUnsignedWrap()))
991  return X;
992  // If X has the form X = A / Y, then X * Y cannot overflow.
993  if ((IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) ||
994  (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1)))))
995  return X;
996  }
997 
998  // (X rem Y) / Y -> 0
999  if ((IsSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1000  (!IsSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1001  return Constant::getNullValue(Op0->getType());
1002 
1003  // (X /u C1) /u C2 -> 0 if C1 * C2 overflow
1004  ConstantInt *C1, *C2;
1005  if (!IsSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
1006  match(Op1, m_ConstantInt(C2))) {
1007  bool Overflow;
1008  (void)C1->getValue().umul_ov(C2->getValue(), Overflow);
1009  if (Overflow)
1010  return Constant::getNullValue(Op0->getType());
1011  }
1012 
1013  // If the operation is with the result of a select instruction, check whether
1014  // operating on either branch of the select always yields the same value.
1015  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1016  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1017  return V;
1018 
1019  // If the operation is with the result of a phi instruction, check whether
1020  // operating on all incoming values of the phi always yields the same value.
1021  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1022  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1023  return V;
1024 
1025  if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned))
1026  return Constant::getNullValue(Op0->getType());
1027 
1028  return nullptr;
1029 }
1030 
1031 /// These are simplifications common to SRem and URem.
1033  const SimplifyQuery &Q, unsigned MaxRecurse) {
1034  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1035  return C;
1036 
1037  if (Value *V = simplifyDivRem(Op0, Op1, false))
1038  return V;
1039 
1040  // (X % Y) % Y -> X % Y
1041  if ((Opcode == Instruction::SRem &&
1042  match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1043  (Opcode == Instruction::URem &&
1044  match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1045  return Op0;
1046 
1047  // (X << Y) % X -> 0
1048  if ((Opcode == Instruction::SRem &&
1049  match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) ||
1050  (Opcode == Instruction::URem &&
1051  match(Op0, m_NUWShl(m_Specific(Op1), m_Value()))))
1052  return Constant::getNullValue(Op0->getType());
1053 
1054  // If the operation is with the result of a select instruction, check whether
1055  // operating on either branch of the select always yields the same value.
1056  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1057  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1058  return V;
1059 
1060  // If the operation is with the result of a phi instruction, check whether
1061  // operating on all incoming values of the phi always yields the same value.
1062  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1063  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1064  return V;
1065 
1066  // If X / Y == 0, then X % Y == X.
1067  if (isDivZero(Op0, Op1, Q, MaxRecurse, Opcode == Instruction::SRem))
1068  return Op0;
1069 
1070  return nullptr;
1071 }
1072 
1073 /// Given operands for an SDiv, see if we can fold the result.
1074 /// If not, this returns null.
1075 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1076  unsigned MaxRecurse) {
1077  return simplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse);
1078 }
1079 
1082 }
1083 
1084 /// Given operands for a UDiv, see if we can fold the result.
1085 /// If not, this returns null.
1086 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1087  unsigned MaxRecurse) {
1088  return simplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse);
1089 }
1090 
1093 }
1094 
1095 /// Given operands for an SRem, see if we can fold the result.
1096 /// If not, this returns null.
1097 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1098  unsigned MaxRecurse) {
1099  return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse);
1100 }
1101 
1104 }
1105 
1106 /// Given operands for a URem, see if we can fold the result.
1107 /// If not, this returns null.
1108 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1109  unsigned MaxRecurse) {
1110  return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse);
1111 }
1112 
1115 }
1116 
1117 /// Returns true if a shift by \c Amount always yields undef.
1118 static bool isUndefShift(Value *Amount) {
1119  Constant *C = dyn_cast<Constant>(Amount);
1120  if (!C)
1121  return false;
1122 
1123  // X shift by undef -> undef because it may shift by the bitwidth.
1124  if (isa<UndefValue>(C))
1125  return true;
1126 
1127  // Shifting by the bitwidth or more is undefined.
1128  if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
1129  if (CI->getValue().getLimitedValue() >=
1130  CI->getType()->getScalarSizeInBits())
1131  return true;
1132 
1133  // If all lanes of a vector shift are undefined the whole shift is.
1134  if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
1135  for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I)
1137  return false;
1138  return true;
1139  }
1140 
1141  return false;
1142 }
1143 
1144 /// Given operands for an Shl, LShr or AShr, see if we can fold the result.
1145 /// If not, this returns null.
1147  Value *Op1, const SimplifyQuery &Q, unsigned MaxRecurse) {
1148  if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1149  return C;
1150 
1151  // 0 shift by X -> 0
1152  if (match(Op0, m_Zero()))
1153  return Constant::getNullValue(Op0->getType());
1154 
1155  // X shift by 0 -> X
1156  if (match(Op1, m_Zero()))
1157  return Op0;
1158 
1159  // Fold undefined shifts.
1160  if (isUndefShift(Op1))
1161  return UndefValue::get(Op0->getType());
1162 
1163  // If the operation is with the result of a select instruction, check whether
1164  // operating on either branch of the select always yields the same value.
1165  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1166  if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1167  return V;
1168 
1169  // If the operation is with the result of a phi instruction, check whether
1170  // operating on all incoming values of the phi always yields the same value.
1171  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1172  if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1173  return V;
1174 
1175  // If any bits in the shift amount make that value greater than or equal to
1176  // the number of bits in the type, the shift is undefined.
1177  KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1178  if (Known.One.getLimitedValue() >= Known.getBitWidth())
1179  return UndefValue::get(Op0->getType());
1180 
1181  // If all valid bits in the shift amount are known zero, the first operand is
1182  // unchanged.
1183  unsigned NumValidShiftBits = Log2_32_Ceil(Known.getBitWidth());
1184  if (Known.countMinTrailingZeros() >= NumValidShiftBits)
1185  return Op0;
1186 
1187  return nullptr;
1188 }
1189 
1190 /// Given operands for an Shl, LShr or AShr, see if we can
1191 /// fold the result. If not, this returns null.
1193  Value *Op1, bool isExact, const SimplifyQuery &Q,
1194  unsigned MaxRecurse) {
1195  if (Value *V = SimplifyShift(Opcode, Op0, Op1, Q, MaxRecurse))
1196  return V;
1197 
1198  // X >> X -> 0
1199  if (Op0 == Op1)
1200  return Constant::getNullValue(Op0->getType());
1201 
1202  // undef >> X -> 0
1203  // undef >> X -> undef (if it's exact)
1204  if (match(Op0, m_Undef()))
1205  return isExact ? Op0 : Constant::getNullValue(Op0->getType());
1206 
1207  // The low bit cannot be shifted out of an exact shift if it is set.
1208  if (isExact) {
1209  KnownBits Op0Known = computeKnownBits(Op0, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
1210  if (Op0Known.One[0])
1211  return Op0;
1212  }
1213 
1214  return nullptr;
1215 }
1216 
1217 /// Given operands for an Shl, see if we can fold the result.
1218 /// If not, this returns null.
1219 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1220  const SimplifyQuery &Q, unsigned MaxRecurse) {
1221  if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1222  return V;
1223 
1224  // undef << X -> 0
1225  // undef << X -> undef if (if it's NSW/NUW)
1226  if (match(Op0, m_Undef()))
1227  return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType());
1228 
1229  // (X >> A) << A -> X
1230  Value *X;
1231  if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1232  return X;
1233 
1234  // shl nuw i8 C, %x -> C iff C has sign bit set.
1235  if (isNUW && match(Op0, m_Negative()))
1236  return Op0;
1237  // NOTE: could use computeKnownBits() / LazyValueInfo,
1238  // but the cost-benefit analysis suggests it isn't worth it.
1239 
1240  return nullptr;
1241 }
1242 
1243 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1244  const SimplifyQuery &Q) {
1245  return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
1246 }
1247 
1248 /// Given operands for an LShr, see if we can fold the result.
1249 /// If not, this returns null.
1250 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1251  const SimplifyQuery &Q, unsigned MaxRecurse) {
1252  if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q,
1253  MaxRecurse))
1254  return V;
1255 
1256  // (X << A) >> A -> X
1257  Value *X;
1258  if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
1259  return X;
1260 
1261  return nullptr;
1262 }
1263 
1264 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1265  const SimplifyQuery &Q) {
1266  return ::SimplifyLShrInst(Op0, Op1, isExact, Q, RecursionLimit);
1267 }
1268 
1269 /// Given operands for an AShr, see if we can fold the result.
1270 /// If not, this returns null.
1271 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1272  const SimplifyQuery &Q, unsigned MaxRecurse) {
1273  if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
1274  MaxRecurse))
1275  return V;
1276 
1277  // all ones >>a X -> -1
1278  // Do not return Op0 because it may contain undef elements if it's a vector.
1279  if (match(Op0, m_AllOnes()))
1280  return Constant::getAllOnesValue(Op0->getType());
1281 
1282  // (X << A) >> A -> X
1283  Value *X;
1284  if (match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
1285  return X;
1286 
1287  // Arithmetic shifting an all-sign-bit value is a no-op.
1288  unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1289  if (NumSignBits == Op0->getType()->getScalarSizeInBits())
1290  return Op0;
1291 
1292  return nullptr;
1293 }
1294 
1295 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1296  const SimplifyQuery &Q) {
1297  return ::SimplifyAShrInst(Op0, Op1, isExact, Q, RecursionLimit);
1298 }
1299 
1300 /// Commuted variants are assumed to be handled by calling this function again
1301 /// with the parameters swapped.
1303  ICmpInst *UnsignedICmp, bool IsAnd) {
1304  Value *X, *Y;
1305 
1306  ICmpInst::Predicate EqPred;
1307  if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) ||
1308  !ICmpInst::isEquality(EqPred))
1309  return nullptr;
1310 
1311  ICmpInst::Predicate UnsignedPred;
1312  if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
1313  ICmpInst::isUnsigned(UnsignedPred))
1314  ;
1315  else if (match(UnsignedICmp,
1316  m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) &&
1317  ICmpInst::isUnsigned(UnsignedPred))
1318  UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
1319  else
1320  return nullptr;
1321 
1322  // X < Y && Y != 0 --> X < Y
1323  // X < Y || Y != 0 --> Y != 0
1324  if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE)
1325  return IsAnd ? UnsignedICmp : ZeroICmp;
1326 
1327  // X >= Y || Y != 0 --> true
1328  // X >= Y || Y == 0 --> X >= Y
1329  if (UnsignedPred == ICmpInst::ICMP_UGE && !IsAnd) {
1330  if (EqPred == ICmpInst::ICMP_NE)
1331  return getTrue(UnsignedICmp->getType());
1332  return UnsignedICmp;
1333  }
1334 
1335  // X < Y && Y == 0 --> false
1336  if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
1337  IsAnd)
1338  return getFalse(UnsignedICmp->getType());
1339 
1340  return nullptr;
1341 }
1342 
1343 /// Commuted variants are assumed to be handled by calling this function again
1344 /// with the parameters swapped.
1346  ICmpInst::Predicate Pred0, Pred1;
1347  Value *A ,*B;
1348  if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
1349  !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
1350  return nullptr;
1351 
1352  // We have (icmp Pred0, A, B) & (icmp Pred1, A, B).
1353  // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
1354  // can eliminate Op1 from this 'and'.
1355  if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
1356  return Op0;
1357 
1358  // Check for any combination of predicates that are guaranteed to be disjoint.
1359  if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
1360  (Pred0 == ICmpInst::ICMP_EQ && ICmpInst::isFalseWhenEqual(Pred1)) ||
1361  (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT) ||
1362  (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT))
1363  return getFalse(Op0->getType());
1364 
1365  return nullptr;
1366 }
1367 
1368 /// Commuted variants are assumed to be handled by calling this function again
1369 /// with the parameters swapped.
1371  ICmpInst::Predicate Pred0, Pred1;
1372  Value *A ,*B;
1373  if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
1374  !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
1375  return nullptr;
1376 
1377  // We have (icmp Pred0, A, B) | (icmp Pred1, A, B).
1378  // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
1379  // can eliminate Op0 from this 'or'.
1380  if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
1381  return Op1;
1382 
1383  // Check for any combination of predicates that cover the entire range of
1384  // possibilities.
1385  if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
1386  (Pred0 == ICmpInst::ICMP_NE && ICmpInst::isTrueWhenEqual(Pred1)) ||
1387  (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGE) ||
1388  (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGE))
1389  return getTrue(Op0->getType());
1390 
1391  return nullptr;
1392 }
1393 
1394 /// Test if a pair of compares with a shared operand and 2 constants has an
1395 /// empty set intersection, full set union, or if one compare is a superset of
1396 /// the other.
1398  bool IsAnd) {
1399  // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)).
1400  if (Cmp0->getOperand(0) != Cmp1->getOperand(0))
1401  return nullptr;
1402 
1403  const APInt *C0, *C1;
1404  if (!match(Cmp0->getOperand(1), m_APInt(C0)) ||
1405  !match(Cmp1->getOperand(1), m_APInt(C1)))
1406  return nullptr;
1407 
1408  auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0);
1409  auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1);
1410 
1411  // For and-of-compares, check if the intersection is empty:
1412  // (icmp X, C0) && (icmp X, C1) --> empty set --> false
1413  if (IsAnd && Range0.intersectWith(Range1).isEmptySet())
1414  return getFalse(Cmp0->getType());
1415 
1416  // For or-of-compares, check if the union is full:
1417  // (icmp X, C0) || (icmp X, C1) --> full set --> true
1418  if (!IsAnd && Range0.unionWith(Range1).isFullSet())
1419  return getTrue(Cmp0->getType());
1420 
1421  // Is one range a superset of the other?
1422  // If this is and-of-compares, take the smaller set:
1423  // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42
1424  // If this is or-of-compares, take the larger set:
1425  // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4
1426  if (Range0.contains(Range1))
1427  return IsAnd ? Cmp1 : Cmp0;
1428  if (Range1.contains(Range0))
1429  return IsAnd ? Cmp0 : Cmp1;
1430 
1431  return nullptr;
1432 }
1433 
1435  bool IsAnd) {
1436  ICmpInst::Predicate P0 = Cmp0->getPredicate(), P1 = Cmp1->getPredicate();
1437  if (!match(Cmp0->getOperand(1), m_Zero()) ||
1438  !match(Cmp1->getOperand(1), m_Zero()) || P0 != P1)
1439  return nullptr;
1440 
1441  if ((IsAnd && P0 != ICmpInst::ICMP_NE) || (!IsAnd && P1 != ICmpInst::ICMP_EQ))
1442  return nullptr;
1443 
1444  // We have either "(X == 0 || Y == 0)" or "(X != 0 && Y != 0)".
1445  Value *X = Cmp0->getOperand(0);
1446  Value *Y = Cmp1->getOperand(0);
1447 
1448  // If one of the compares is a masked version of a (not) null check, then
1449  // that compare implies the other, so we eliminate the other. Optionally, look
1450  // through a pointer-to-int cast to match a null check of a pointer type.
1451 
1452  // (X == 0) || (([ptrtoint] X & ?) == 0) --> ([ptrtoint] X & ?) == 0
1453  // (X == 0) || ((? & [ptrtoint] X) == 0) --> (? & [ptrtoint] X) == 0
1454  // (X != 0) && (([ptrtoint] X & ?) != 0) --> ([ptrtoint] X & ?) != 0
1455  // (X != 0) && ((? & [ptrtoint] X) != 0) --> (? & [ptrtoint] X) != 0
1456  if (match(Y, m_c_And(m_Specific(X), m_Value())) ||
1458  return Cmp1;
1459 
1460  // (([ptrtoint] Y & ?) == 0) || (Y == 0) --> ([ptrtoint] Y & ?) == 0
1461  // ((? & [ptrtoint] Y) == 0) || (Y == 0) --> (? & [ptrtoint] Y) == 0
1462  // (([ptrtoint] Y & ?) != 0) && (Y != 0) --> ([ptrtoint] Y & ?) != 0
1463  // ((? & [ptrtoint] Y) != 0) && (Y != 0) --> (? & [ptrtoint] Y) != 0
1464  if (match(X, m_c_And(m_Specific(Y), m_Value())) ||
1466  return Cmp0;
1467 
1468  return nullptr;
1469 }
1470 
1472  // (icmp (add V, C0), C1) & (icmp V, C0)
1473  ICmpInst::Predicate Pred0, Pred1;
1474  const APInt *C0, *C1;
1475  Value *V;
1476  if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1477  return nullptr;
1478 
1479  if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1480  return nullptr;
1481 
1482  auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1483  if (AddInst->getOperand(1) != Op1->getOperand(1))
1484  return nullptr;
1485 
1486  Type *ITy = Op0->getType();
1487  bool isNSW = AddInst->hasNoSignedWrap();
1488  bool isNUW = AddInst->hasNoUnsignedWrap();
1489 
1490  const APInt Delta = *C1 - *C0;
1491  if (C0->isStrictlyPositive()) {
1492  if (Delta == 2) {
1493  if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
1494  return getFalse(ITy);
1495  if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1496  return getFalse(ITy);
1497  }
1498  if (Delta == 1) {
1499  if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
1500  return getFalse(ITy);
1501  if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1502  return getFalse(ITy);
1503  }
1504  }
1505  if (C0->getBoolValue() && isNUW) {
1506  if (Delta == 2)
1507  if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
1508  return getFalse(ITy);
1509  if (Delta == 1)
1510  if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
1511  return getFalse(ITy);
1512  }
1513 
1514  return nullptr;
1515 }
1516 
1518  if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true))
1519  return X;
1520  if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true))
1521  return X;
1522 
1523  if (Value *X = simplifyAndOfICmpsWithSameOperands(Op0, Op1))
1524  return X;
1525  if (Value *X = simplifyAndOfICmpsWithSameOperands(Op1, Op0))
1526  return X;
1527 
1528  if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true))
1529  return X;
1530 
1531  if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, true))
1532  return X;
1533 
1534  if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1))
1535  return X;
1536  if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0))
1537  return X;
1538 
1539  return nullptr;
1540 }
1541 
1543  // (icmp (add V, C0), C1) | (icmp V, C0)
1544  ICmpInst::Predicate Pred0, Pred1;
1545  const APInt *C0, *C1;
1546  Value *V;
1547  if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1548  return nullptr;
1549 
1550  if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1551  return nullptr;
1552 
1553  auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1554  if (AddInst->getOperand(1) != Op1->getOperand(1))
1555  return nullptr;
1556 
1557  Type *ITy = Op0->getType();
1558  bool isNSW = AddInst->hasNoSignedWrap();
1559  bool isNUW = AddInst->hasNoUnsignedWrap();
1560 
1561  const APInt Delta = *C1 - *C0;
1562  if (C0->isStrictlyPositive()) {
1563  if (Delta == 2) {
1564  if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
1565  return getTrue(ITy);
1566  if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1567  return getTrue(ITy);
1568  }
1569  if (Delta == 1) {
1570  if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
1571  return getTrue(ITy);
1572  if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1573  return getTrue(ITy);
1574  }
1575  }
1576  if (C0->getBoolValue() && isNUW) {
1577  if (Delta == 2)
1578  if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
1579  return getTrue(ITy);
1580  if (Delta == 1)
1581  if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
1582  return getTrue(ITy);
1583  }
1584 
1585  return nullptr;
1586 }
1587 
1589  if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false))
1590  return X;
1591  if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false))
1592  return X;
1593 
1594  if (Value *X = simplifyOrOfICmpsWithSameOperands(Op0, Op1))
1595  return X;
1596  if (Value *X = simplifyOrOfICmpsWithSameOperands(Op1, Op0))
1597  return X;
1598 
1599  if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false))
1600  return X;
1601 
1602  if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, false))
1603  return X;
1604 
1605  if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1))
1606  return X;
1607  if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0))
1608  return X;
1609 
1610  return nullptr;
1611 }
1612 
1613 static Value *simplifyAndOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
1614  Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
1615  Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
1616  if (LHS0->getType() != RHS0->getType())
1617  return nullptr;
1618 
1619  FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
1620  if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) ||
1621  (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) {
1622  // (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y
1623  // (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X
1624  // (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y
1625  // (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X
1626  // (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y
1627  // (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X
1628  // (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y
1629  // (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X
1630  if ((isKnownNeverNaN(LHS0) && (LHS1 == RHS0 || LHS1 == RHS1)) ||
1631  (isKnownNeverNaN(LHS1) && (LHS0 == RHS0 || LHS0 == RHS1)))
1632  return RHS;
1633 
1634  // (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y
1635  // (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X
1636  // (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y
1637  // (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X
1638  // (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y
1639  // (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X
1640  // (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y
1641  // (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X
1642  if ((isKnownNeverNaN(RHS0) && (RHS1 == LHS0 || RHS1 == LHS1)) ||
1643  (isKnownNeverNaN(RHS1) && (RHS0 == LHS0 || RHS0 == LHS1)))
1644  return LHS;
1645  }
1646 
1647  return nullptr;
1648 }
1649 
1650 static Value *simplifyAndOrOfCmps(Value *Op0, Value *Op1, bool IsAnd) {
1651  // Look through casts of the 'and' operands to find compares.
1652  auto *Cast0 = dyn_cast<CastInst>(Op0);
1653  auto *Cast1 = dyn_cast<CastInst>(Op1);
1654  if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() &&
1655  Cast0->getSrcTy() == Cast1->getSrcTy()) {
1656  Op0 = Cast0->getOperand(0);
1657  Op1 = Cast1->getOperand(0);
1658  }
1659 
1660  Value *V = nullptr;
1661  auto *ICmp0 = dyn_cast<ICmpInst>(Op0);
1662  auto *ICmp1 = dyn_cast<ICmpInst>(Op1);
1663  if (ICmp0 && ICmp1)
1664  V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1) :
1665  simplifyOrOfICmps(ICmp0, ICmp1);
1666 
1667  auto *FCmp0 = dyn_cast<FCmpInst>(Op0);
1668  auto *FCmp1 = dyn_cast<FCmpInst>(Op1);
1669  if (FCmp0 && FCmp1)
1670  V = simplifyAndOrOfFCmps(FCmp0, FCmp1, IsAnd);
1671 
1672  if (!V)
1673  return nullptr;
1674  if (!Cast0)
1675  return V;
1676 
1677  // If we looked through casts, we can only handle a constant simplification
1678  // because we are not allowed to create a cast instruction here.
1679  if (auto *C = dyn_cast<Constant>(V))
1680  return ConstantExpr::getCast(Cast0->getOpcode(), C, Cast0->getType());
1681 
1682  return nullptr;
1683 }
1684 
1685 /// Given operands for an And, see if we can fold the result.
1686 /// If not, this returns null.
1687 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1688  unsigned MaxRecurse) {
1689  if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q))
1690  return C;
1691 
1692  // X & undef -> 0
1693  if (match(Op1, m_Undef()))
1694  return Constant::getNullValue(Op0->getType());
1695 
1696  // X & X = X
1697  if (Op0 == Op1)
1698  return Op0;
1699 
1700  // X & 0 = 0
1701  if (match(Op1, m_Zero()))
1702  return Constant::getNullValue(Op0->getType());
1703 
1704  // X & -1 = X
1705  if (match(Op1, m_AllOnes()))
1706  return Op0;
1707 
1708  // A & ~A = ~A & A = 0
1709  if (match(Op0, m_Not(m_Specific(Op1))) ||
1710  match(Op1, m_Not(m_Specific(Op0))))
1711  return Constant::getNullValue(Op0->getType());
1712 
1713  // (A | ?) & A = A
1714  if (match(Op0, m_c_Or(m_Specific(Op1), m_Value())))
1715  return Op1;
1716 
1717  // A & (A | ?) = A
1718  if (match(Op1, m_c_Or(m_Specific(Op0), m_Value())))
1719  return Op0;
1720 
1721  // A mask that only clears known zeros of a shifted value is a no-op.
1722  Value *X;
1723  const APInt *Mask;
1724  const APInt *ShAmt;
1725  if (match(Op1, m_APInt(Mask))) {
1726  // If all bits in the inverted and shifted mask are clear:
1727  // and (shl X, ShAmt), Mask --> shl X, ShAmt
1728  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) &&
1729  (~(*Mask)).lshr(*ShAmt).isNullValue())
1730  return Op0;
1731 
1732  // If all bits in the inverted and shifted mask are clear:
1733  // and (lshr X, ShAmt), Mask --> lshr X, ShAmt
1734  if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) &&
1735  (~(*Mask)).shl(*ShAmt).isNullValue())
1736  return Op0;
1737  }
1738 
1739  // A & (-A) = A if A is a power of two or zero.
1740  if (match(Op0, m_Neg(m_Specific(Op1))) ||
1741  match(Op1, m_Neg(m_Specific(Op0)))) {
1742  if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1743  Q.DT))
1744  return Op0;
1745  if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1746  Q.DT))
1747  return Op1;
1748  }
1749 
1750  if (Value *V = simplifyAndOrOfCmps(Op0, Op1, true))
1751  return V;
1752 
1753  // Try some generic simplifications for associative operations.
1754  if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1755  MaxRecurse))
1756  return V;
1757 
1758  // And distributes over Or. Try some generic simplifications based on this.
1759  if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1760  Q, MaxRecurse))
1761  return V;
1762 
1763  // And distributes over Xor. Try some generic simplifications based on this.
1764  if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1765  Q, MaxRecurse))
1766  return V;
1767 
1768  // If the operation is with the result of a select instruction, check whether
1769  // operating on either branch of the select always yields the same value.
1770  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1771  if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1772  MaxRecurse))
1773  return V;
1774 
1775  // If the operation is with the result of a phi instruction, check whether
1776  // operating on all incoming values of the phi always yields the same value.
1777  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1778  if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1779  MaxRecurse))
1780  return V;
1781 
1782  return nullptr;
1783 }
1784 
1787 }
1788 
1789 /// Given operands for an Or, see if we can fold the result.
1790 /// If not, this returns null.
1791 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1792  unsigned MaxRecurse) {
1793  if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q))
1794  return C;
1795 
1796  // X | undef -> -1
1797  // X | -1 = -1
1798  // Do not return Op1 because it may contain undef elements if it's a vector.
1799  if (match(Op1, m_Undef()) || match(Op1, m_AllOnes()))
1800  return Constant::getAllOnesValue(Op0->getType());
1801 
1802  // X | X = X
1803  // X | 0 = X
1804  if (Op0 == Op1 || match(Op1, m_Zero()))
1805  return Op0;
1806 
1807  // A | ~A = ~A | A = -1
1808  if (match(Op0, m_Not(m_Specific(Op1))) ||
1809  match(Op1, m_Not(m_Specific(Op0))))
1810  return Constant::getAllOnesValue(Op0->getType());
1811 
1812  // (A & ?) | A = A
1813  if (match(Op0, m_c_And(m_Specific(Op1), m_Value())))
1814  return Op1;
1815 
1816  // A | (A & ?) = A
1817  if (match(Op1, m_c_And(m_Specific(Op0), m_Value())))
1818  return Op0;
1819 
1820  // ~(A & ?) | A = -1
1821  if (match(Op0, m_Not(m_c_And(m_Specific(Op1), m_Value()))))
1822  return Constant::getAllOnesValue(Op1->getType());
1823 
1824  // A | ~(A & ?) = -1
1825  if (match(Op1, m_Not(m_c_And(m_Specific(Op1), m_Value()))))
1826  return Constant::getAllOnesValue(Op0->getType());
1827 
1828  Value *A, *B;
1829  // (A & ~B) | (A ^ B) -> (A ^ B)
1830  // (~B & A) | (A ^ B) -> (A ^ B)
1831  // (A & ~B) | (B ^ A) -> (B ^ A)
1832  // (~B & A) | (B ^ A) -> (B ^ A)
1833  if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
1834  (match(Op0, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
1835  match(Op0, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
1836  return Op1;
1837 
1838  // Commute the 'or' operands.
1839  // (A ^ B) | (A & ~B) -> (A ^ B)
1840  // (A ^ B) | (~B & A) -> (A ^ B)
1841  // (B ^ A) | (A & ~B) -> (B ^ A)
1842  // (B ^ A) | (~B & A) -> (B ^ A)
1843  if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
1844  (match(Op1, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
1845  match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
1846  return Op0;
1847 
1848  // (A & B) | (~A ^ B) -> (~A ^ B)
1849  // (B & A) | (~A ^ B) -> (~A ^ B)
1850  // (A & B) | (B ^ ~A) -> (B ^ ~A)
1851  // (B & A) | (B ^ ~A) -> (B ^ ~A)
1852  if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1853  (match(Op1, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
1854  match(Op1, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
1855  return Op1;
1856 
1857  // (~A ^ B) | (A & B) -> (~A ^ B)
1858  // (~A ^ B) | (B & A) -> (~A ^ B)
1859  // (B ^ ~A) | (A & B) -> (B ^ ~A)
1860  // (B ^ ~A) | (B & A) -> (B ^ ~A)
1861  if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1862  (match(Op0, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
1863  match(Op0, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
1864  return Op0;
1865 
1866  if (Value *V = simplifyAndOrOfCmps(Op0, Op1, false))
1867  return V;
1868 
1869  // Try some generic simplifications for associative operations.
1870  if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1871  MaxRecurse))
1872  return V;
1873 
1874  // Or distributes over And. Try some generic simplifications based on this.
1875  if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1876  MaxRecurse))
1877  return V;
1878 
1879  // If the operation is with the result of a select instruction, check whether
1880  // operating on either branch of the select always yields the same value.
1881  if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1882  if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1883  MaxRecurse))
1884  return V;
1885 
1886  // (A & C1)|(B & C2)
1887  const APInt *C1, *C2;
1888  if (match(Op0, m_And(m_Value(A), m_APInt(C1))) &&
1889  match(Op1, m_And(m_Value(B), m_APInt(C2)))) {
1890  if (*C1 == ~*C2) {
1891  // (A & C1)|(B & C2)
1892  // If we have: ((V + N) & C1) | (V & C2)
1893  // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1894  // replace with V+N.
1895  Value *N;
1896  if (C2->isMask() && // C2 == 0+1+
1897  match(A, m_c_Add(m_Specific(B), m_Value(N)))) {
1898  // Add commutes, try both ways.
1899  if (MaskedValueIsZero(N, *C2, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1900  return A;
1901  }
1902  // Or commutes, try both ways.
1903  if (C1->isMask() &&
1904  match(B, m_c_Add(m_Specific(A), m_Value(N)))) {
1905  // Add commutes, try both ways.
1906  if (MaskedValueIsZero(N, *C1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1907  return B;
1908  }
1909  }
1910  }
1911 
1912  // If the operation is with the result of a phi instruction, check whether
1913  // operating on all incoming values of the phi always yields the same value.
1914  if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1915  if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1916  return V;
1917 
1918  return nullptr;
1919 }
1920 
1923 }
1924 
1925 /// Given operands for a Xor, see if we can fold the result.
1926 /// If not, this returns null.
1927 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1928  unsigned MaxRecurse) {
1929  if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q))
1930  return C;
1931 
1932  // A ^ undef -> undef
1933  if (match(Op1, m_Undef()))
1934  return Op1;
1935 
1936  // A ^ 0 = A
1937  if (match(Op1, m_Zero()))
1938  return Op0;
1939 
1940  // A ^ A = 0
1941  if (Op0 == Op1)
1942  return Constant::getNullValue(Op0->getType());
1943 
1944  // A ^ ~A = ~A ^ A = -1
1945  if (match(Op0, m_Not(m_Specific(Op1))) ||
1946  match(Op1, m_Not(m_Specific(Op0))))
1947  return Constant::getAllOnesValue(Op0->getType());
1948 
1949  // Try some generic simplifications for associative operations.
1950  if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1951  MaxRecurse))
1952  return V;
1953 
1954  // Threading Xor over selects and phi nodes is pointless, so don't bother.
1955  // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1956  // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1957  // only if B and C are equal. If B and C are equal then (since we assume
1958  // that operands have already been simplified) "select(cond, B, C)" should
1959  // have been simplified to the common value of B and C already. Analysing
1960  // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1961  // for threading over phi nodes.
1962 
1963  return nullptr;
1964 }
1965 
1968 }
1969 
1970 
1972  return CmpInst::makeCmpResultType(Op->getType());
1973 }
1974 
1975 /// Rummage around inside V looking for something equivalent to the comparison
1976 /// "LHS Pred RHS". Return such a value if found, otherwise return null.
1977 /// Helper function for analyzing max/min idioms.
1979  Value *LHS, Value *RHS) {
1981  if (!SI)
1982  return nullptr;
1983  CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1984  if (!Cmp)
1985  return nullptr;
1986  Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1987  if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1988  return Cmp;
1989  if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1990  LHS == CmpRHS && RHS == CmpLHS)
1991  return Cmp;
1992  return nullptr;
1993 }
1994 
1995 // A significant optimization not implemented here is assuming that alloca
1996 // addresses are not equal to incoming argument values. They don't *alias*,
1997 // as we say, but that doesn't mean they aren't equal, so we take a
1998 // conservative approach.
1999 //
2000 // This is inspired in part by C++11 5.10p1:
2001 // "Two pointers of the same type compare equal if and only if they are both
2002 // null, both point to the same function, or both represent the same
2003 // address."
2004 //
2005 // This is pretty permissive.
2006 //
2007 // It's also partly due to C11 6.5.9p6:
2008 // "Two pointers compare equal if and only if both are null pointers, both are
2009 // pointers to the same object (including a pointer to an object and a
2010 // subobject at its beginning) or function, both are pointers to one past the
2011 // last element of the same array object, or one is a pointer to one past the
2012 // end of one array object and the other is a pointer to the start of a
2013 // different array object that happens to immediately follow the first array
2014 // object in the address space.)
2015 //
2016 // C11's version is more restrictive, however there's no reason why an argument
2017 // couldn't be a one-past-the-end value for a stack object in the caller and be
2018 // equal to the beginning of a stack object in the callee.
2019 //
2020 // If the C and C++ standards are ever made sufficiently restrictive in this
2021 // area, it may be possible to update LLVM's semantics accordingly and reinstate
2022 // this optimization.
2023 static Constant *
2025  const DominatorTree *DT, CmpInst::Predicate Pred,
2026  AssumptionCache *AC, const Instruction *CxtI,
2027  Value *LHS, Value *RHS) {
2028  // First, skip past any trivial no-ops.
2029  LHS = LHS->stripPointerCasts();
2030  RHS = RHS->stripPointerCasts();
2031 
2032  // A non-null pointer is not equal to a null pointer.
2033  if (llvm::isKnownNonZero(LHS, DL) && isa<ConstantPointerNull>(RHS) &&
2034  (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE))
2035  return ConstantInt::get(GetCompareTy(LHS),
2036  !CmpInst::isTrueWhenEqual(Pred));
2037 
2038  // We can only fold certain predicates on pointer comparisons.
2039  switch (Pred) {
2040  default:
2041  return nullptr;
2042 
2043  // Equality comaprisons are easy to fold.
2044  case CmpInst::ICMP_EQ:
2045  case CmpInst::ICMP_NE:
2046  break;
2047 
2048  // We can only handle unsigned relational comparisons because 'inbounds' on
2049  // a GEP only protects against unsigned wrapping.
2050  case CmpInst::ICMP_UGT:
2051  case CmpInst::ICMP_UGE:
2052  case CmpInst::ICMP_ULT:
2053  case CmpInst::ICMP_ULE:
2054  // However, we have to switch them to their signed variants to handle
2055  // negative indices from the base pointer.
2056  Pred = ICmpInst::getSignedPredicate(Pred);
2057  break;
2058  }
2059 
2060  // Strip off any constant offsets so that we can reason about them.
2061  // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
2062  // here and compare base addresses like AliasAnalysis does, however there are
2063  // numerous hazards. AliasAnalysis and its utilities rely on special rules
2064  // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
2065  // doesn't need to guarantee pointer inequality when it says NoAlias.
2066  Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
2067  Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
2068 
2069  // If LHS and RHS are related via constant offsets to the same base
2070  // value, we can replace it with an icmp which just compares the offsets.
2071  if (LHS == RHS)
2072  return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
2073 
2074  // Various optimizations for (in)equality comparisons.
2075  if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
2076  // Different non-empty allocations that exist at the same time have
2077  // different addresses (if the program can tell). Global variables always
2078  // exist, so they always exist during the lifetime of each other and all
2079  // allocas. Two different allocas usually have different addresses...
2080  //
2081  // However, if there's an @llvm.stackrestore dynamically in between two
2082  // allocas, they may have the same address. It's tempting to reduce the
2083  // scope of the problem by only looking at *static* allocas here. That would
2084  // cover the majority of allocas while significantly reducing the likelihood
2085  // of having an @llvm.stackrestore pop up in the middle. However, it's not
2086  // actually impossible for an @llvm.stackrestore to pop up in the middle of
2087  // an entry block. Also, if we have a block that's not attached to a
2088  // function, we can't tell if it's "static" under the current definition.
2089  // Theoretically, this problem could be fixed by creating a new kind of
2090  // instruction kind specifically for static allocas. Such a new instruction
2091  // could be required to be at the top of the entry block, thus preventing it
2092  // from being subject to a @llvm.stackrestore. Instcombine could even
2093  // convert regular allocas into these special allocas. It'd be nifty.
2094  // However, until then, this problem remains open.
2095  //
2096  // So, we'll assume that two non-empty allocas have different addresses
2097  // for now.
2098  //
2099  // With all that, if the offsets are within the bounds of their allocations
2100  // (and not one-past-the-end! so we can't use inbounds!), and their
2101  // allocations aren't the same, the pointers are not equal.
2102  //
2103  // Note that it's not necessary to check for LHS being a global variable
2104  // address, due to canonicalization and constant folding.
2105  if (isa<AllocaInst>(LHS) &&
2106  (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
2107  ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
2108  ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
2109  uint64_t LHSSize, RHSSize;
2110  if (LHSOffsetCI && RHSOffsetCI &&
2111  getObjectSize(LHS, LHSSize, DL, TLI) &&
2112  getObjectSize(RHS, RHSSize, DL, TLI)) {
2113  const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
2114  const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
2115  if (!LHSOffsetValue.isNegative() &&
2116  !RHSOffsetValue.isNegative() &&
2117  LHSOffsetValue.ult(LHSSize) &&
2118  RHSOffsetValue.ult(RHSSize)) {
2119  return ConstantInt::get(GetCompareTy(LHS),
2120  !CmpInst::isTrueWhenEqual(Pred));
2121  }
2122  }
2123 
2124  // Repeat the above check but this time without depending on DataLayout
2125  // or being able to compute a precise size.
2126  if (!cast<PointerType>(LHS->getType())->isEmptyTy() &&
2127  !cast<PointerType>(RHS->getType())->isEmptyTy() &&
2128  LHSOffset->isNullValue() &&
2129  RHSOffset->isNullValue())
2130  return ConstantInt::get(GetCompareTy(LHS),
2131  !CmpInst::isTrueWhenEqual(Pred));
2132  }
2133 
2134  // Even if an non-inbounds GEP occurs along the path we can still optimize
2135  // equality comparisons concerning the result. We avoid walking the whole
2136  // chain again by starting where the last calls to
2137  // stripAndComputeConstantOffsets left off and accumulate the offsets.
2138  Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true);
2139  Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true);
2140  if (LHS == RHS)
2141  return ConstantExpr::getICmp(Pred,
2142  ConstantExpr::getAdd(LHSOffset, LHSNoBound),
2143  ConstantExpr::getAdd(RHSOffset, RHSNoBound));
2144 
2145  // If one side of the equality comparison must come from a noalias call
2146  // (meaning a system memory allocation function), and the other side must
2147  // come from a pointer that cannot overlap with dynamically-allocated
2148  // memory within the lifetime of the current function (allocas, byval
2149  // arguments, globals), then determine the comparison result here.
2150  SmallVector<Value *, 8> LHSUObjs, RHSUObjs;
2151  GetUnderlyingObjects(LHS, LHSUObjs, DL);
2152  GetUnderlyingObjects(RHS, RHSUObjs, DL);
2153 
2154  // Is the set of underlying objects all noalias calls?
2155  auto IsNAC = [](ArrayRef<Value *> Objects) {
2156  return all_of(Objects, isNoAliasCall);
2157  };
2158 
2159  // Is the set of underlying objects all things which must be disjoint from
2160  // noalias calls. For allocas, we consider only static ones (dynamic
2161  // allocas might be transformed into calls to malloc not simultaneously
2162  // live with the compared-to allocation). For globals, we exclude symbols
2163  // that might be resolve lazily to symbols in another dynamically-loaded
2164  // library (and, thus, could be malloc'ed by the implementation).
2165  auto IsAllocDisjoint = [](ArrayRef<Value *> Objects) {
2166  return all_of(Objects, [](Value *V) {
2167  if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
2168  return AI->getParent() && AI->getFunction() && AI->isStaticAlloca();
2169  if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
2170  return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() ||
2171  GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) &&
2172  !GV->isThreadLocal();
2173  if (const Argument *A = dyn_cast<Argument>(V))
2174  return A->hasByValAttr();
2175  return false;
2176  });
2177  };
2178 
2179  if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
2180  (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
2181  return ConstantInt::get(GetCompareTy(LHS),
2182  !CmpInst::isTrueWhenEqual(Pred));
2183 
2184  // Fold comparisons for non-escaping pointer even if the allocation call
2185  // cannot be elided. We cannot fold malloc comparison to null. Also, the
2186  // dynamic allocation call could be either of the operands.
2187  Value *MI = nullptr;
2188  if (isAllocLikeFn(LHS, TLI) &&
2189  llvm::isKnownNonZero(RHS, DL, 0, nullptr, CxtI, DT))
2190  MI = LHS;
2191  else if (isAllocLikeFn(RHS, TLI) &&
2192  llvm::isKnownNonZero(LHS, DL, 0, nullptr, CxtI, DT))
2193  MI = RHS;
2194  // FIXME: We should also fold the compare when the pointer escapes, but the
2195  // compare dominates the pointer escape
2196  if (MI && !PointerMayBeCaptured(MI, true, true))
2197  return ConstantInt::get(GetCompareTy(LHS),
2199  }
2200 
2201  // Otherwise, fail.
2202  return nullptr;
2203 }
2204 
2205 /// Fold an icmp when its operands have i1 scalar type.
2207  Value *RHS, const SimplifyQuery &Q) {
2208  Type *ITy = GetCompareTy(LHS); // The return type.
2209  Type *OpTy = LHS->getType(); // The operand type.
2210  if (!OpTy->isIntOrIntVectorTy(1))
2211  return nullptr;
2212 
2213  // A boolean compared to true/false can be simplified in 14 out of the 20
2214  // (10 predicates * 2 constants) possible combinations. Cases not handled here
2215  // require a 'not' of the LHS, so those must be transformed in InstCombine.
2216  if (match(RHS, m_Zero())) {
2217  switch (Pred) {
2218  case CmpInst::ICMP_NE: // X != 0 -> X
2219  case CmpInst::ICMP_UGT: // X >u 0 -> X
2220  case CmpInst::ICMP_SLT: // X <s 0 -> X
2221  return LHS;
2222 
2223  case CmpInst::ICMP_ULT: // X <u 0 -> false
2224  case CmpInst::ICMP_SGT: // X >s 0 -> false
2225  return getFalse(ITy);
2226 
2227  case CmpInst::ICMP_UGE: // X >=u 0 -> true
2228  case CmpInst::ICMP_SLE: // X <=s 0 -> true
2229  return getTrue(ITy);
2230 
2231  default: break;
2232  }
2233  } else if (match(RHS, m_One())) {
2234  switch (Pred) {
2235  case CmpInst::ICMP_EQ: // X == 1 -> X
2236  case CmpInst::ICMP_UGE: // X >=u 1 -> X
2237  case CmpInst::ICMP_SLE: // X <=s -1 -> X
2238  return LHS;
2239 
2240  case CmpInst::ICMP_UGT: // X >u 1 -> false
2241  case CmpInst::ICMP_SLT: // X <s -1 -> false
2242  return getFalse(ITy);
2243 
2244  case CmpInst::ICMP_ULE: // X <=u 1 -> true
2245  case CmpInst::ICMP_SGE: // X >=s -1 -> true
2246  return getTrue(ITy);
2247 
2248  default: break;
2249  }
2250  }
2251 
2252  switch (Pred) {
2253  default:
2254  break;
2255  case ICmpInst::ICMP_UGE:
2256  if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
2257  return getTrue(ITy);
2258  break;
2259  case ICmpInst::ICMP_SGE:
2260  /// For signed comparison, the values for an i1 are 0 and -1
2261  /// respectively. This maps into a truth table of:
2262  /// LHS | RHS | LHS >=s RHS | LHS implies RHS
2263  /// 0 | 0 | 1 (0 >= 0) | 1
2264  /// 0 | 1 | 1 (0 >= -1) | 1
2265  /// 1 | 0 | 0 (-1 >= 0) | 0
2266  /// 1 | 1 | 1 (-1 >= -1) | 1
2267  if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
2268  return getTrue(ITy);
2269  break;
2270  case ICmpInst::ICMP_ULE:
2271  if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
2272  return getTrue(ITy);
2273  break;
2274  }
2275 
2276  return nullptr;
2277 }
2278 
2279 /// Try hard to fold icmp with zero RHS because this is a common case.
2281  Value *RHS, const SimplifyQuery &Q) {
2282  if (!match(RHS, m_Zero()))
2283  return nullptr;
2284 
2285  Type *ITy = GetCompareTy(LHS); // The return type.
2286  switch (Pred) {
2287  default:
2288  llvm_unreachable("Unknown ICmp predicate!");
2289  case ICmpInst::ICMP_ULT:
2290  return getFalse(ITy);
2291  case ICmpInst::ICMP_UGE:
2292  return getTrue(ITy);
2293  case ICmpInst::ICMP_EQ:
2294  case ICmpInst::ICMP_ULE:
2295  if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2296  return getFalse(ITy);
2297  break;
2298  case ICmpInst::ICMP_NE:
2299  case ICmpInst::ICMP_UGT:
2300  if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2301  return getTrue(ITy);
2302  break;
2303  case ICmpInst::ICMP_SLT: {
2304  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2305  if (LHSKnown.isNegative())
2306  return getTrue(ITy);
2307  if (LHSKnown.isNonNegative())
2308  return getFalse(ITy);
2309  break;
2310  }
2311  case ICmpInst::ICMP_SLE: {
2312  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2313  if (LHSKnown.isNegative())
2314  return getTrue(ITy);
2315  if (LHSKnown.isNonNegative() &&
2316  isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2317  return getFalse(ITy);
2318  break;
2319  }
2320  case ICmpInst::ICMP_SGE: {
2321  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2322  if (LHSKnown.isNegative())
2323  return getFalse(ITy);
2324  if (LHSKnown.isNonNegative())
2325  return getTrue(ITy);
2326  break;
2327  }
2328  case ICmpInst::ICMP_SGT: {
2329  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2330  if (LHSKnown.isNegative())
2331  return getFalse(ITy);
2332  if (LHSKnown.isNonNegative() &&
2333  isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2334  return getTrue(ITy);
2335  break;
2336  }
2337  }
2338 
2339  return nullptr;
2340 }
2341 
2342 /// Many binary operators with a constant operand have an easy-to-compute
2343 /// range of outputs. This can be used to fold a comparison to always true or
2344 /// always false.
2345 static void setLimitsForBinOp(BinaryOperator &BO, APInt &Lower, APInt &Upper) {
2346  unsigned Width = Lower.getBitWidth();
2347  const APInt *C;
2348  switch (BO.getOpcode()) {
2349  case Instruction::Add:
2350  if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) {
2351  // FIXME: If we have both nuw and nsw, we should reduce the range further.
2352  if (BO.hasNoUnsignedWrap()) {
2353  // 'add nuw x, C' produces [C, UINT_MAX].
2354  Lower = *C;
2355  } else if (BO.hasNoSignedWrap()) {
2356  if (C->isNegative()) {
2357  // 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C].
2358  Lower = APInt::getSignedMinValue(Width);
2359  Upper = APInt::getSignedMaxValue(Width) + *C + 1;
2360  } else {
2361  // 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX].
2362  Lower = APInt::getSignedMinValue(Width) + *C;
2363  Upper = APInt::getSignedMaxValue(Width) + 1;
2364  }
2365  }
2366  }
2367  break;
2368 
2369  case Instruction::And:
2370  if (match(BO.getOperand(1), m_APInt(C)))
2371  // 'and x, C' produces [0, C].
2372  Upper = *C + 1;
2373  break;
2374 
2375  case Instruction::Or:
2376  if (match(BO.getOperand(1), m_APInt(C)))
2377  // 'or x, C' produces [C, UINT_MAX].
2378  Lower = *C;
2379  break;
2380 
2381  case Instruction::AShr:
2382  if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) {
2383  // 'ashr x, C' produces [INT_MIN >> C, INT_MAX >> C].
2384  Lower = APInt::getSignedMinValue(Width).ashr(*C);
2385  Upper = APInt::getSignedMaxValue(Width).ashr(*C) + 1;
2386  } else if (match(BO.getOperand(0), m_APInt(C))) {
2387  unsigned ShiftAmount = Width - 1;
2388  if (!C->isNullValue() && BO.isExact())
2389  ShiftAmount = C->countTrailingZeros();
2390  if (C->isNegative()) {
2391  // 'ashr C, x' produces [C, C >> (Width-1)]
2392  Lower = *C;
2393  Upper = C->ashr(ShiftAmount) + 1;
2394  } else {
2395  // 'ashr C, x' produces [C >> (Width-1), C]
2396  Lower = C->ashr(ShiftAmount);
2397  Upper = *C + 1;
2398  }
2399  }
2400  break;
2401 
2402  case Instruction::LShr:
2403  if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) {
2404  // 'lshr x, C' produces [0, UINT_MAX >> C].
2405  Upper = APInt::getAllOnesValue(Width).lshr(*C) + 1;
2406  } else if (match(BO.getOperand(0), m_APInt(C))) {
2407  // 'lshr C, x' produces [C >> (Width-1), C].
2408  unsigned ShiftAmount = Width - 1;
2409  if (!C->isNullValue() && BO.isExact())
2410  ShiftAmount = C->countTrailingZeros();
2411  Lower = C->lshr(ShiftAmount);
2412  Upper = *C + 1;
2413  }
2414  break;
2415 
2416  case Instruction::Shl:
2417  if (match(BO.getOperand(0), m_APInt(C))) {
2418  if (BO.hasNoUnsignedWrap()) {
2419  // 'shl nuw C, x' produces [C, C << CLZ(C)]
2420  Lower = *C;
2421  Upper = Lower.shl(Lower.countLeadingZeros()) + 1;
2422  } else if (BO.hasNoSignedWrap()) { // TODO: What if both nuw+nsw?
2423  if (C->isNegative()) {
2424  // 'shl nsw C, x' produces [C << CLO(C)-1, C]
2425  unsigned ShiftAmount = C->countLeadingOnes() - 1;
2426  Lower = C->shl(ShiftAmount);
2427  Upper = *C + 1;
2428  } else {
2429  // 'shl nsw C, x' produces [C, C << CLZ(C)-1]
2430  unsigned ShiftAmount = C->countLeadingZeros() - 1;
2431  Lower = *C;
2432  Upper = C->shl(ShiftAmount) + 1;
2433  }
2434  }
2435  }
2436  break;
2437 
2438  case Instruction::SDiv:
2439  if (match(BO.getOperand(1), m_APInt(C))) {
2440  APInt IntMin = APInt::getSignedMinValue(Width);
2441  APInt IntMax = APInt::getSignedMaxValue(Width);
2442  if (C->isAllOnesValue()) {
2443  // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
2444  // where C != -1 and C != 0 and C != 1
2445  Lower = IntMin + 1;
2446  Upper = IntMax + 1;
2447  } else if (C->countLeadingZeros() < Width - 1) {
2448  // 'sdiv x, C' produces [INT_MIN / C, INT_MAX / C]
2449  // where C != -1 and C != 0 and C != 1
2450  Lower = IntMin.sdiv(*C);
2451  Upper = IntMax.sdiv(*C);
2452  if (Lower.sgt(Upper))
2453  std::swap(Lower, Upper);
2454  Upper = Upper + 1;
2455  assert(Upper != Lower && "Upper part of range has wrapped!");
2456  }
2457  } else if (match(BO.getOperand(0), m_APInt(C))) {
2458  if (C->isMinSignedValue()) {
2459  // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
2460  Lower = *C;
2461  Upper = Lower.lshr(1) + 1;
2462  } else {
2463  // 'sdiv C, x' produces [-|C|, |C|].
2464  Upper = C->abs() + 1;
2465  Lower = (-Upper) + 1;
2466  }
2467  }
2468  break;
2469 
2470  case Instruction::UDiv:
2471  if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) {
2472  // 'udiv x, C' produces [0, UINT_MAX / C].
2473  Upper = APInt::getMaxValue(Width).udiv(*C) + 1;
2474  } else if (match(BO.getOperand(0), m_APInt(C))) {
2475  // 'udiv C, x' produces [0, C].
2476  Upper = *C + 1;
2477  }
2478  break;
2479 
2480  case Instruction::SRem:
2481  if (match(BO.getOperand(1), m_APInt(C))) {
2482  // 'srem x, C' produces (-|C|, |C|).
2483  Upper = C->abs();
2484  Lower = (-Upper) + 1;
2485  }
2486  break;
2487 
2488  case Instruction::URem:
2489  if (match(BO.getOperand(1), m_APInt(C)))
2490  // 'urem x, C' produces [0, C).
2491  Upper = *C;
2492  break;
2493 
2494  default:
2495  break;
2496  }
2497 }
2498 
2500  Value *RHS) {
2501  Type *ITy = GetCompareTy(RHS); // The return type.
2502 
2503  Value *X;
2504  // Sign-bit checks can be optimized to true/false after unsigned
2505  // floating-point casts:
2506  // icmp slt (bitcast (uitofp X)), 0 --> false
2507  // icmp sgt (bitcast (uitofp X)), -1 --> true
2508  if (match(LHS, m_BitCast(m_UIToFP(m_Value(X))))) {
2509  if (Pred == ICmpInst::ICMP_SLT && match(RHS, m_Zero()))
2510  return ConstantInt::getFalse(ITy);
2511  if (Pred == ICmpInst::ICMP_SGT && match(RHS, m_AllOnes()))
2512  return ConstantInt::getTrue(ITy);
2513  }
2514 
2515  const APInt *C;
2516  if (!match(RHS, m_APInt(C)))
2517  return nullptr;
2518 
2519  // Rule out tautological comparisons (eg., ult 0 or uge 0).
2521  if (RHS_CR.isEmptySet())
2522  return ConstantInt::getFalse(ITy);
2523  if (RHS_CR.isFullSet())
2524  return ConstantInt::getTrue(ITy);
2525 
2526  // Find the range of possible values for binary operators.
2527  unsigned Width = C->getBitWidth();
2528  APInt Lower = APInt(Width, 0);
2529  APInt Upper = APInt(Width, 0);
2530  if (auto *BO = dyn_cast<BinaryOperator>(LHS))
2531  setLimitsForBinOp(*BO, Lower, Upper);
2532 
2533  ConstantRange LHS_CR =
2534  Lower != Upper ? ConstantRange(Lower, Upper) : ConstantRange(Width, true);
2535 
2536  if (auto *I = dyn_cast<Instruction>(LHS))
2537  if (auto *Ranges = I->getMetadata(LLVMContext::MD_range))
2538  LHS_CR = LHS_CR.intersectWith(getConstantRangeFromMetadata(*Ranges));
2539 
2540  if (!LHS_CR.isFullSet()) {
2541  if (RHS_CR.contains(LHS_CR))
2542  return ConstantInt::getTrue(ITy);
2543  if (RHS_CR.inverse().contains(LHS_CR))
2544  return ConstantInt::getFalse(ITy);
2545  }
2546 
2547  return nullptr;
2548 }
2549 
2550 /// TODO: A large part of this logic is duplicated in InstCombine's
2551 /// foldICmpBinOp(). We should be able to share that and avoid the code
2552 /// duplication.
2554  Value *RHS, const SimplifyQuery &Q,
2555  unsigned MaxRecurse) {
2556  Type *ITy = GetCompareTy(LHS); // The return type.
2557 
2558  BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2559  BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2560  if (MaxRecurse && (LBO || RBO)) {
2561  // Analyze the case when either LHS or RHS is an add instruction.
2562  Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2563  // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2564  bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2565  if (LBO && LBO->getOpcode() == Instruction::Add) {
2566  A = LBO->getOperand(0);
2567  B = LBO->getOperand(1);
2568  NoLHSWrapProblem =
2569  ICmpInst::isEquality(Pred) ||
2570  (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
2571  (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
2572  }
2573  if (RBO && RBO->getOpcode() == Instruction::Add) {
2574  C = RBO->getOperand(0);
2575  D = RBO->getOperand(1);
2576  NoRHSWrapProblem =
2577  ICmpInst::isEquality(Pred) ||
2578  (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2579  (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2580  }
2581 
2582  // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2583  if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2584  if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2585  Constant::getNullValue(RHS->getType()), Q,
2586  MaxRecurse - 1))
2587  return V;
2588 
2589  // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2590  if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2591  if (Value *V =
2593  C == LHS ? D : C, Q, MaxRecurse - 1))
2594  return V;
2595 
2596  // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2597  if (A && C && (A == C || A == D || B == C || B == D) && NoLHSWrapProblem &&
2598  NoRHSWrapProblem) {
2599  // Determine Y and Z in the form icmp (X+Y), (X+Z).
2600  Value *Y, *Z;
2601  if (A == C) {
2602  // C + B == C + D -> B == D
2603  Y = B;
2604  Z = D;
2605  } else if (A == D) {
2606  // D + B == C + D -> B == C
2607  Y = B;
2608  Z = C;
2609  } else if (B == C) {
2610  // A + C == C + D -> A == D
2611  Y = A;
2612  Z = D;
2613  } else {
2614  assert(B == D);
2615  // A + D == C + D -> A == C
2616  Y = A;
2617  Z = C;
2618  }
2619  if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1))
2620  return V;
2621  }
2622  }
2623 
2624  {
2625  Value *Y = nullptr;
2626  // icmp pred (or X, Y), X
2627  if (LBO && match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) {
2628  if (Pred == ICmpInst::ICMP_ULT)
2629  return getFalse(ITy);
2630  if (Pred == ICmpInst::ICMP_UGE)
2631  return getTrue(ITy);
2632 
2633  if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) {
2634  KnownBits RHSKnown = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2635  KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2636  if (RHSKnown.isNonNegative() && YKnown.isNegative())
2637  return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy);
2638  if (RHSKnown.isNegative() || YKnown.isNonNegative())
2639  return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy);
2640  }
2641  }
2642  // icmp pred X, (or X, Y)
2643  if (RBO && match(RBO, m_c_Or(m_Value(Y), m_Specific(LHS)))) {
2644  if (Pred == ICmpInst::ICMP_ULE)
2645  return getTrue(ITy);
2646  if (Pred == ICmpInst::ICMP_UGT)
2647  return getFalse(ITy);
2648 
2649  if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLE) {
2650  KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2651  KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2652  if (LHSKnown.isNonNegative() && YKnown.isNegative())
2653  return Pred == ICmpInst::ICMP_SGT ? getTrue(ITy) : getFalse(ITy);
2654  if (LHSKnown.isNegative() || YKnown.isNonNegative())
2655  return Pred == ICmpInst::ICMP_SGT ? getFalse(ITy) : getTrue(ITy);
2656  }
2657  }
2658  }
2659 
2660  // icmp pred (and X, Y), X
2661  if (LBO && match(LBO, m_c_And(m_Value(), m_Specific(RHS)))) {
2662  if (Pred == ICmpInst::ICMP_UGT)
2663  return getFalse(ITy);
2664  if (Pred == ICmpInst::ICMP_ULE)
2665  return getTrue(ITy);
2666  }
2667  // icmp pred X, (and X, Y)
2668  if (RBO && match(RBO, m_c_And(m_Value(), m_Specific(LHS)))) {
2669  if (Pred == ICmpInst::ICMP_UGE)
2670  return getTrue(ITy);
2671  if (Pred == ICmpInst::ICMP_ULT)
2672  return getFalse(ITy);
2673  }
2674 
2675  // 0 - (zext X) pred C
2676  if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
2677  if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
2678  if (RHSC->getValue().isStrictlyPositive()) {
2679  if (Pred == ICmpInst::ICMP_SLT)
2680  return ConstantInt::getTrue(RHSC->getContext());
2681  if (Pred == ICmpInst::ICMP_SGE)
2682  return ConstantInt::getFalse(RHSC->getContext());
2683  if (Pred == ICmpInst::ICMP_EQ)
2684  return ConstantInt::getFalse(RHSC->getContext());
2685  if (Pred == ICmpInst::ICMP_NE)
2686  return ConstantInt::getTrue(RHSC->getContext());
2687  }
2688  if (RHSC->getValue().isNonNegative()) {
2689  if (Pred == ICmpInst::ICMP_SLE)
2690  return ConstantInt::getTrue(RHSC->getContext());
2691  if (Pred == ICmpInst::ICMP_SGT)
2692  return ConstantInt::getFalse(RHSC->getContext());
2693  }
2694  }
2695  }
2696 
2697  // icmp pred (urem X, Y), Y
2698  if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2699  switch (Pred) {
2700  default:
2701  break;
2702  case ICmpInst::ICMP_SGT:
2703  case ICmpInst::ICMP_SGE: {
2704  KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2705  if (!Known.isNonNegative())
2706  break;
2708  }
2709  case ICmpInst::ICMP_EQ:
2710  case ICmpInst::ICMP_UGT:
2711  case ICmpInst::ICMP_UGE:
2712  return getFalse(ITy);
2713  case ICmpInst::ICMP_SLT:
2714  case ICmpInst::ICMP_SLE: {
2715  KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2716  if (!Known.isNonNegative())
2717  break;
2719  }
2720  case ICmpInst::ICMP_NE:
2721  case ICmpInst::ICMP_ULT:
2722  case ICmpInst::ICMP_ULE:
2723  return getTrue(ITy);
2724  }
2725  }
2726 
2727  // icmp pred X, (urem Y, X)
2728  if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2729  switch (Pred) {
2730  default:
2731  break;
2732  case ICmpInst::ICMP_SGT:
2733  case ICmpInst::ICMP_SGE: {
2734  KnownBits Known = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2735  if (!Known.isNonNegative())
2736  break;
2738  }
2739  case ICmpInst::ICMP_NE:
2740  case ICmpInst::ICMP_UGT:
2741  case ICmpInst::ICMP_UGE:
2742  return getTrue(ITy);
2743  case ICmpInst::ICMP_SLT:
2744  case ICmpInst::ICMP_SLE: {
2745  KnownBits Known = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
2746  if (!Known.isNonNegative())
2747  break;
2749  }
2750  case ICmpInst::ICMP_EQ:
2751  case ICmpInst::ICMP_ULT:
2752  case ICmpInst::ICMP_ULE:
2753  return getFalse(ITy);
2754  }
2755  }
2756 
2757  // x >> y <=u x
2758  // x udiv y <=u x.
2759  if (LBO && (match(LBO, m_LShr(m_Specific(RHS), m_Value())) ||
2760  match(LBO, m_UDiv(m_Specific(RHS), m_Value())))) {
2761  // icmp pred (X op Y), X
2762  if (Pred == ICmpInst::ICMP_UGT)
2763  return getFalse(ITy);
2764  if (Pred == ICmpInst::ICMP_ULE)
2765  return getTrue(ITy);
2766  }
2767 
2768  // x >=u x >> y
2769  // x >=u x udiv y.
2770  if (RBO && (match(RBO, m_LShr(m_Specific(LHS), m_Value())) ||
2771  match(RBO, m_UDiv(m_Specific(LHS), m_Value())))) {
2772  // icmp pred X, (X op Y)
2773  if (Pred == ICmpInst::ICMP_ULT)
2774  return getFalse(ITy);
2775  if (Pred == ICmpInst::ICMP_UGE)
2776  return getTrue(ITy);
2777  }
2778 
2779  // handle:
2780  // CI2 << X == CI
2781  // CI2 << X != CI
2782  //
2783  // where CI2 is a power of 2 and CI isn't
2784  if (auto *CI = dyn_cast<ConstantInt>(RHS)) {
2785  const APInt *CI2Val, *CIVal = &CI->getValue();
2786  if (LBO && match(LBO, m_Shl(m_APInt(CI2Val), m_Value())) &&
2787  CI2Val->isPowerOf2()) {
2788  if (!CIVal->isPowerOf2()) {
2789  // CI2 << X can equal zero in some circumstances,
2790  // this simplification is unsafe if CI is zero.
2791  //
2792  // We know it is safe if:
2793  // - The shift is nsw, we can't shift out the one bit.
2794  // - The shift is nuw, we can't shift out the one bit.
2795  // - CI2 is one
2796  // - CI isn't zero
2797  if (LBO->hasNoSignedWrap() || LBO->hasNoUnsignedWrap() ||
2798  CI2Val->isOneValue() || !CI->isZero()) {
2799  if (Pred == ICmpInst::ICMP_EQ)
2800  return ConstantInt::getFalse(RHS->getContext());
2801  if (Pred == ICmpInst::ICMP_NE)
2802  return ConstantInt::getTrue(RHS->getContext());
2803  }
2804  }
2805  if (CIVal->isSignMask() && CI2Val->isOneValue()) {
2806  if (Pred == ICmpInst::ICMP_UGT)
2807  return ConstantInt::getFalse(RHS->getContext());
2808  if (Pred == ICmpInst::ICMP_ULE)
2809  return ConstantInt::getTrue(RHS->getContext());
2810  }
2811  }
2812  }
2813 
2814  if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2815  LBO->getOperand(1) == RBO->getOperand(1)) {
2816  switch (LBO->getOpcode()) {
2817  default:
2818  break;
2819  case Instruction::UDiv:
2820  case Instruction::LShr:
2821  if (ICmpInst::isSigned(Pred) || !LBO->isExact() || !RBO->isExact())
2822  break;
2823  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2824  RBO->getOperand(0), Q, MaxRecurse - 1))
2825  return V;
2826  break;
2827  case Instruction::SDiv:
2828  if (!ICmpInst::isEquality(Pred) || !LBO->isExact() || !RBO->isExact())
2829  break;
2830  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2831  RBO->getOperand(0), Q, MaxRecurse - 1))
2832  return V;
2833  break;
2834  case Instruction::AShr:
2835  if (!LBO->isExact() || !RBO->isExact())
2836  break;
2837  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2838  RBO->getOperand(0), Q, MaxRecurse - 1))
2839  return V;
2840  break;
2841  case Instruction::Shl: {
2842  bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2843  bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2844  if (!NUW && !NSW)
2845  break;
2846  if (!NSW && ICmpInst::isSigned(Pred))
2847  break;
2848  if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2849  RBO->getOperand(0), Q, MaxRecurse - 1))
2850  return V;
2851  break;
2852  }
2853  }
2854  }
2855  return nullptr;
2856 }
2857 
2858 /// Simplify integer comparisons where at least one operand of the compare
2859 /// matches an integer min/max idiom.
2861  Value *RHS, const SimplifyQuery &Q,
2862  unsigned MaxRecurse) {
2863  Type *ITy = GetCompareTy(LHS); // The return type.
2864  Value *A, *B;
2866  CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2867 
2868  // Signed variants on "max(a,b)>=a -> true".
2869  if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2870  if (A != RHS)
2871  std::swap(A, B); // smax(A, B) pred A.
2872  EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2873  // We analyze this as smax(A, B) pred A.
2874  P = Pred;
2875  } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2876  (A == LHS || B == LHS)) {
2877  if (A != LHS)
2878  std::swap(A, B); // A pred smax(A, B).
2879  EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2880  // We analyze this as smax(A, B) swapped-pred A.
2881  P = CmpInst::getSwappedPredicate(Pred);
2882  } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2883  (A == RHS || B == RHS)) {
2884  if (A != RHS)
2885  std::swap(A, B); // smin(A, B) pred A.
2886  EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2887  // We analyze this as smax(-A, -B) swapped-pred -A.
2888  // Note that we do not need to actually form -A or -B thanks to EqP.
2889  P = CmpInst::getSwappedPredicate(Pred);
2890  } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2891  (A == LHS || B == LHS)) {
2892  if (A != LHS)
2893  std::swap(A, B); // A pred smin(A, B).
2894  EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2895  // We analyze this as smax(-A, -B) pred -A.
2896  // Note that we do not need to actually form -A or -B thanks to EqP.
2897  P = Pred;
2898  }
2899  if (P != CmpInst::BAD_ICMP_PREDICATE) {
2900  // Cases correspond to "max(A, B) p A".
2901  switch (P) {
2902  default:
2903  break;
2904  case CmpInst::ICMP_EQ:
2905  case CmpInst::ICMP_SLE:
2906  // Equivalent to "A EqP B". This may be the same as the condition tested
2907  // in the max/min; if so, we can just return that.
2908  if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2909  return V;
2910  if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2911  return V;
2912  // Otherwise, see if "A EqP B" simplifies.
2913  if (MaxRecurse)
2914  if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
2915  return V;
2916  break;
2917  case CmpInst::ICMP_NE:
2918  case CmpInst::ICMP_SGT: {
2920  // Equivalent to "A InvEqP B". This may be the same as the condition
2921  // tested in the max/min; if so, we can just return that.
2922  if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2923  return V;
2924  if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2925  return V;
2926  // Otherwise, see if "A InvEqP B" simplifies.
2927  if (MaxRecurse)
2928  if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
2929  return V;
2930  break;
2931  }
2932  case CmpInst::ICMP_SGE:
2933  // Always true.
2934  return getTrue(ITy);
2935  case CmpInst::ICMP_SLT:
2936  // Always false.
2937  return getFalse(ITy);
2938  }
2939  }
2940 
2941  // Unsigned variants on "max(a,b)>=a -> true".
2943  if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2944  if (A != RHS)
2945  std::swap(A, B); // umax(A, B) pred A.
2946  EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2947  // We analyze this as umax(A, B) pred A.
2948  P = Pred;
2949  } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2950  (A == LHS || B == LHS)) {
2951  if (A != LHS)
2952  std::swap(A, B); // A pred umax(A, B).
2953  EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2954  // We analyze this as umax(A, B) swapped-pred A.
2955  P = CmpInst::getSwappedPredicate(Pred);
2956  } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2957  (A == RHS || B == RHS)) {
2958  if (A != RHS)
2959  std::swap(A, B); // umin(A, B) pred A.
2960  EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2961  // We analyze this as umax(-A, -B) swapped-pred -A.
2962  // Note that we do not need to actually form -A or -B thanks to EqP.
2963  P = CmpInst::getSwappedPredicate(Pred);
2964  } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2965  (A == LHS || B == LHS)) {
2966  if (A != LHS)
2967  std::swap(A, B); // A pred umin(A, B).
2968  EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2969  // We analyze this as umax(-A, -B) pred -A.
2970  // Note that we do not need to actually form -A or -B thanks to EqP.
2971  P = Pred;
2972  }
2973  if (P != CmpInst::BAD_ICMP_PREDICATE) {
2974  // Cases correspond to "max(A, B) p A".
2975  switch (P) {
2976  default:
2977  break;
2978  case CmpInst::ICMP_EQ:
2979  case CmpInst::ICMP_ULE:
2980  // Equivalent to "A EqP B". This may be the same as the condition tested
2981  // in the max/min; if so, we can just return that.
2982  if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2983  return V;
2984  if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2985  return V;
2986  // Otherwise, see if "A EqP B" simplifies.
2987  if (MaxRecurse)
2988  if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
2989  return V;
2990  break;
2991  case CmpInst::ICMP_NE:
2992  case CmpInst::ICMP_UGT: {
2994  // Equivalent to "A InvEqP B". This may be the same as the condition
2995  // tested in the max/min; if so, we can just return that.
2996  if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2997  return V;
2998  if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2999  return V;
3000  // Otherwise, see if "A InvEqP B" simplifies.
3001  if (MaxRecurse)
3002  if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
3003  return V;
3004  break;
3005  }
3006  case CmpInst::ICMP_UGE:
3007  // Always true.
3008  return getTrue(ITy);
3009  case CmpInst::ICMP_ULT:
3010  // Always false.
3011  return getFalse(ITy);
3012  }
3013  }
3014 
3015  // Variants on "max(x,y) >= min(x,z)".
3016  Value *C, *D;
3017  if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
3018  match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
3019  (A == C || A == D || B == C || B == D)) {
3020  // max(x, ?) pred min(x, ?).
3021  if (Pred == CmpInst::ICMP_SGE)
3022  // Always true.
3023  return getTrue(ITy);
3024  if (Pred == CmpInst::ICMP_SLT)
3025  // Always false.
3026  return getFalse(ITy);
3027  } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
3028  match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
3029  (A == C || A == D || B == C || B == D)) {
3030  // min(x, ?) pred max(x, ?).
3031  if (Pred == CmpInst::ICMP_SLE)
3032  // Always true.
3033  return getTrue(ITy);
3034  if (Pred == CmpInst::ICMP_SGT)
3035  // Always false.
3036  return getFalse(ITy);
3037  } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
3038  match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
3039  (A == C || A == D || B == C || B == D)) {
3040  // max(x, ?) pred min(x, ?).
3041  if (Pred == CmpInst::ICMP_UGE)
3042  // Always true.
3043  return getTrue(ITy);
3044  if (Pred == CmpInst::ICMP_ULT)
3045  // Always false.
3046  return getFalse(ITy);
3047  } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
3048  match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
3049  (A == C || A == D || B == C || B == D)) {
3050  // min(x, ?) pred max(x, ?).
3051  if (Pred == CmpInst::ICMP_ULE)
3052  // Always true.
3053  return getTrue(ITy);
3054  if (Pred == CmpInst::ICMP_UGT)
3055  // Always false.
3056  return getFalse(ITy);
3057  }
3058 
3059  return nullptr;
3060 }
3061 
3062 /// Given operands for an ICmpInst, see if we can fold the result.
3063 /// If not, this returns null.
3064 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3065  const SimplifyQuery &Q, unsigned MaxRecurse) {
3066  CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3067  assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
3068 
3069  if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3070  if (Constant *CRHS = dyn_cast<Constant>(RHS))
3071  return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3072 
3073  // If we have a constant, make sure it is on the RHS.
3074  std::swap(LHS, RHS);
3075  Pred = CmpInst::getSwappedPredicate(Pred);
3076  }
3077 
3078  Type *ITy = GetCompareTy(LHS); // The return type.
3079 
3080  // icmp X, X -> true/false
3081  // icmp X, undef -> true/false because undef could be X.
3082  if (LHS == RHS || isa<UndefValue>(RHS))
3083  return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
3084 
3085  if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
3086  return V;
3087 
3088  if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
3089  return V;
3090 
3091  if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS))
3092  return V;
3093 
3094  // If both operands have range metadata, use the metadata
3095  // to simplify the comparison.
3096  if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) {
3097  auto RHS_Instr = cast<Instruction>(RHS);
3098  auto LHS_Instr = cast<Instruction>(LHS);
3099 
3100  if (RHS_Instr->getMetadata(LLVMContext::MD_range) &&
3101  LHS_Instr->getMetadata(LLVMContext::MD_range)) {
3102  auto RHS_CR = getConstantRangeFromMetadata(
3103  *RHS_Instr->getMetadata(LLVMContext::MD_range));
3104  auto LHS_CR = getConstantRangeFromMetadata(
3105  *LHS_Instr->getMetadata(LLVMContext::MD_range));
3106 
3107  auto Satisfied_CR = ConstantRange::makeSatisfyingICmpRegion(Pred, RHS_CR);
3108  if (Satisfied_CR.contains(LHS_CR))
3109  return ConstantInt::getTrue(RHS->getContext());
3110 
3111  auto InversedSatisfied_CR = ConstantRange::makeSatisfyingICmpRegion(
3112  CmpInst::getInversePredicate(Pred), RHS_CR);
3113  if (InversedSatisfied_CR.contains(LHS_CR))
3114  return ConstantInt::getFalse(RHS->getContext());
3115  }
3116  }
3117 
3118  // Compare of cast, for example (zext X) != 0 -> X != 0
3119  if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
3120  Instruction *LI = cast<CastInst>(LHS);
3121  Value *SrcOp = LI->getOperand(0);
3122  Type *SrcTy = SrcOp->getType();
3123  Type *DstTy = LI->getType();
3124 
3125  // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
3126  // if the integer type is the same size as the pointer type.
3127  if (MaxRecurse && isa<PtrToIntInst>(LI) &&
3128  Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
3129  if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
3130  // Transfer the cast to the constant.
3131  if (Value *V = SimplifyICmpInst(Pred, SrcOp,
3132  ConstantExpr::getIntToPtr(RHSC, SrcTy),
3133  Q, MaxRecurse-1))
3134  return V;
3135  } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
3136  if (RI->getOperand(0)->getType() == SrcTy)
3137  // Compare without the cast.
3138  if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
3139  Q, MaxRecurse-1))
3140  return V;
3141  }
3142  }
3143 
3144  if (isa<ZExtInst>(LHS)) {
3145  // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
3146  // same type.
3147  if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
3148  if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3149  // Compare X and Y. Note that signed predicates become unsigned.
3151  SrcOp, RI->getOperand(0), Q,
3152  MaxRecurse-1))
3153  return V;
3154  }
3155  // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
3156  // too. If not, then try to deduce the result of the comparison.
3157  else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
3158  // Compute the constant that would happen if we truncated to SrcTy then
3159  // reextended to DstTy.
3160  Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
3161  Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
3162 
3163  // If the re-extended constant didn't change then this is effectively
3164  // also a case of comparing two zero-extended values.
3165  if (RExt == CI && MaxRecurse)
3167  SrcOp, Trunc, Q, MaxRecurse-1))
3168  return V;
3169 
3170  // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
3171  // there. Use this to work out the result of the comparison.
3172  if (RExt != CI) {
3173  switch (Pred) {
3174  default: llvm_unreachable("Unknown ICmp predicate!");
3175  // LHS <u RHS.
3176  case ICmpInst::ICMP_EQ:
3177  case ICmpInst::ICMP_UGT:
3178  case ICmpInst::ICMP_UGE:
3179  return ConstantInt::getFalse(CI->getContext());
3180 
3181  case ICmpInst::ICMP_NE:
3182  case ICmpInst::ICMP_ULT:
3183  case ICmpInst::ICMP_ULE:
3184  return ConstantInt::getTrue(CI->getContext());
3185 
3186  // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
3187  // is non-negative then LHS <s RHS.
3188  case ICmpInst::ICMP_SGT:
3189  case ICmpInst::ICMP_SGE:
3190  return CI->getValue().isNegative() ?
3191  ConstantInt::getTrue(CI->getContext()) :
3192  ConstantInt::getFalse(CI->getContext());
3193 
3194  case ICmpInst::ICMP_SLT:
3195  case ICmpInst::ICMP_SLE:
3196  return CI->getValue().isNegative() ?
3197  ConstantInt::getFalse(CI->getContext()) :
3198  ConstantInt::getTrue(CI->getContext());
3199  }
3200  }
3201  }
3202  }
3203 
3204  if (isa<SExtInst>(LHS)) {
3205  // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
3206  // same type.
3207  if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
3208  if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3209  // Compare X and Y. Note that the predicate does not change.
3210  if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
3211  Q, MaxRecurse-1))
3212  return V;
3213  }
3214  // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
3215  // too. If not, then try to deduce the result of the comparison.
3216  else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
3217  // Compute the constant that would happen if we truncated to SrcTy then
3218  // reextended to DstTy.
3219  Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
3220  Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
3221 
3222  // If the re-extended constant didn't change then this is effectively
3223  // also a case of comparing two sign-extended values.
3224  if (RExt == CI && MaxRecurse)
3225  if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
3226  return V;
3227 
3228  // Otherwise the upper bits of LHS are all equal, while RHS has varying
3229  // bits there. Use this to work out the result of the comparison.
3230  if (RExt != CI) {
3231  switch (Pred) {
3232  default: llvm_unreachable("Unknown ICmp predicate!");
3233  case ICmpInst::ICMP_EQ:
3234  return ConstantInt::getFalse(CI->getContext());
3235  case ICmpInst::ICMP_NE:
3236  return ConstantInt::getTrue(CI->getContext());
3237 
3238  // If RHS is non-negative then LHS <s RHS. If RHS is negative then
3239  // LHS >s RHS.
3240  case ICmpInst::ICMP_SGT:
3241  case ICmpInst::ICMP_SGE:
3242  return CI->getValue().isNegative() ?
3243  ConstantInt::getTrue(CI->getContext()) :
3244  ConstantInt::getFalse(CI->getContext());
3245  case ICmpInst::ICMP_SLT:
3246  case ICmpInst::ICMP_SLE:
3247  return CI->getValue().isNegative() ?
3248  ConstantInt::getFalse(CI->getContext()) :
3249  ConstantInt::getTrue(CI->getContext());
3250 
3251  // If LHS is non-negative then LHS <u RHS. If LHS is negative then
3252  // LHS >u RHS.
3253  case ICmpInst::ICMP_UGT:
3254  case ICmpInst::ICMP_UGE:
3255  // Comparison is true iff the LHS <s 0.
3256  if (MaxRecurse)
3257  if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
3258  Constant::getNullValue(SrcTy),
3259  Q, MaxRecurse-1))
3260  return V;
3261  break;
3262  case ICmpInst::ICMP_ULT:
3263  case ICmpInst::ICMP_ULE:
3264  // Comparison is true iff the LHS >=s 0.
3265  if (MaxRecurse)
3266  if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
3267  Constant::getNullValue(SrcTy),
3268  Q, MaxRecurse-1))
3269  return V;
3270  break;
3271  }
3272  }
3273  }
3274  }
3275  }
3276 
3277  // icmp eq|ne X, Y -> false|true if X != Y
3278  if (ICmpInst::isEquality(Pred) &&
3279  isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT)) {
3280  return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy);
3281  }
3282 
3283  if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse))
3284  return V;
3285 
3286  if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse))
3287  return V;
3288 
3289  // Simplify comparisons of related pointers using a powerful, recursive
3290  // GEP-walk when we have target data available..
3291  if (LHS->getType()->isPointerTy())
3292  if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.AC, Q.CxtI, LHS,
3293  RHS))
3294  return C;
3295  if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS))
3296  if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS))
3297  if (Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) ==
3298  Q.DL.getTypeSizeInBits(CLHS->getType()) &&
3299  Q.DL.getTypeSizeInBits(CRHS->getPointerOperandType()) ==
3300  Q.DL.getTypeSizeInBits(CRHS->getType()))
3301  if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.AC, Q.CxtI,
3302  CLHS->getPointerOperand(),
3303  CRHS->getPointerOperand()))
3304  return C;
3305 
3306  if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
3307  if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
3308  if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
3309  GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
3310  (ICmpInst::isEquality(Pred) ||
3311  (GLHS->isInBounds() && GRHS->isInBounds() &&
3312  Pred == ICmpInst::getSignedPredicate(Pred)))) {
3313  // The bases are equal and the indices are constant. Build a constant
3314  // expression GEP with the same indices and a null base pointer to see
3315  // what constant folding can make out of it.
3316  Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
3317  SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
3319  GLHS->getSourceElementType(), Null, IndicesLHS);
3320 
3321  SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
3323  GLHS->getSourceElementType(), Null, IndicesRHS);
3324  return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
3325  }
3326  }
3327  }
3328 
3329  // If the comparison is with the result of a select instruction, check whether
3330  // comparing with either branch of the select always yields the same value.
3331  if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3332  if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3333  return V;
3334 
3335  // If the comparison is with the result of a phi instruction, check whether
3336  // doing the compare with each incoming phi value yields a common result.
3337  if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3338  if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3339  return V;
3340 
3341  return nullptr;
3342 }
3343 
3344 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3345  const SimplifyQuery &Q) {
3346  return ::SimplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
3347 }
3348 
3349 /// Given operands for an FCmpInst, see if we can fold the result.
3350 /// If not, this returns null.
3351 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3352  FastMathFlags FMF, const SimplifyQuery &Q,
3353  unsigned MaxRecurse) {
3354  CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3355  assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
3356 
3357  if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3358  if (Constant *CRHS = dyn_cast<Constant>(RHS))
3359  return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3360 
3361  // If we have a constant, make sure it is on the RHS.
3362  std::swap(LHS, RHS);
3363  Pred = CmpInst::getSwappedPredicate(Pred);
3364  }
3365 
3366  // Fold trivial predicates.
3367  Type *RetTy = GetCompareTy(LHS);
3368  if (Pred == FCmpInst::FCMP_FALSE)
3369  return getFalse(RetTy);
3370  if (Pred == FCmpInst::FCMP_TRUE)
3371  return getTrue(RetTy);
3372 
3373  // UNO/ORD predicates can be trivially folded if NaNs are ignored.
3374  if (FMF.noNaNs()) {
3375  if (Pred == FCmpInst::FCMP_UNO)
3376  return getFalse(RetTy);
3377  if (Pred == FCmpInst::FCMP_ORD)
3378  return getTrue(RetTy);
3379  }
3380 
3381  // NaN is unordered; NaN is not ordered.
3383  "Comparison must be either ordered or unordered");
3384  if (match(RHS, m_NaN()))
3385  return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
3386 
3387  // fcmp pred x, undef and fcmp pred undef, x
3388  // fold to true if unordered, false if ordered
3389  if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS)) {
3390  // Choosing NaN for the undef will always make unordered comparison succeed
3391  // and ordered comparison fail.
3392  return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
3393  }
3394 
3395  // fcmp x,x -> true/false. Not all compares are foldable.
3396  if (LHS == RHS) {
3397  if (CmpInst::isTrueWhenEqual(Pred))
3398  return getTrue(RetTy);
3399  if (CmpInst::isFalseWhenEqual(Pred))
3400  return getFalse(RetTy);
3401  }
3402 
3403  // Handle fcmp with constant RHS.
3404  const APFloat *C;
3405  if (match(RHS, m_APFloat(C))) {
3406  // Check whether the constant is an infinity.
3407  if (C->isInfinity()) {
3408  if (C->isNegative()) {
3409  switch (Pred) {
3410  case FCmpInst::FCMP_OLT:
3411  // No value is ordered and less than negative infinity.
3412  return getFalse(RetTy);
3413  case FCmpInst::FCMP_UGE:
3414  // All values are unordered with or at least negative infinity.
3415  return getTrue(RetTy);
3416  default:
3417  break;
3418  }
3419  } else {
3420  switch (Pred) {
3421  case FCmpInst::FCMP_OGT:
3422  // No value is ordered and greater than infinity.
3423  return getFalse(RetTy);
3424  case FCmpInst::FCMP_ULE:
3425  // All values are unordered with and at most infinity.
3426  return getTrue(RetTy);
3427  default:
3428  break;
3429  }
3430  }
3431  }
3432  if (C->isZero()) {
3433  switch (Pred) {
3434  case FCmpInst::FCMP_UGE:
3435  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3436  return getTrue(RetTy);
3437  break;
3438  case FCmpInst::FCMP_OLT:
3439  // X < 0
3440  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3441  return getFalse(RetTy);
3442  break;
3443  default:
3444  break;
3445  }
3446  } else if (C->isNegative()) {
3447  assert(!C->isNaN() && "Unexpected NaN constant!");
3448  // TODO: We can catch more cases by using a range check rather than
3449  // relying on CannotBeOrderedLessThanZero.
3450  switch (Pred) {
3451  case FCmpInst::FCMP_UGE:
3452  case FCmpInst::FCMP_UGT:
3453  case FCmpInst::FCMP_UNE:
3454  // (X >= 0) implies (X > C) when (C < 0)
3455  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3456  return getTrue(RetTy);
3457  break;
3458  case FCmpInst::FCMP_OEQ:
3459  case FCmpInst::FCMP_OLE:
3460  case FCmpInst::FCMP_OLT:
3461  // (X >= 0) implies !(X < C) when (C < 0)
3462  if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3463  return getFalse(RetTy);
3464  break;
3465  default:
3466  break;
3467  }
3468  }
3469  }
3470 
3471  // If the comparison is with the result of a select instruction, check whether
3472  // comparing with either branch of the select always yields the same value.
3473  if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3474  if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3475  return V;
3476 
3477  // If the comparison is with the result of a phi instruction, check whether
3478  // doing the compare with each incoming phi value yields a common result.
3479  if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3480  if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3481  return V;
3482 
3483  return nullptr;
3484 }
3485 
3486 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3487  FastMathFlags FMF, const SimplifyQuery &Q) {
3488  return ::SimplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit);
3489 }
3490 
3491 /// See if V simplifies when its operand Op is replaced with RepOp.
3492 static const Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
3493  const SimplifyQuery &Q,
3494  unsigned MaxRecurse) {
3495  // Trivial replacement.
3496  if (V == Op)
3497  return RepOp;
3498 
3499  // We cannot replace a constant, and shouldn't even try.
3500  if (isa<Constant>(Op))
3501  return nullptr;
3502 
3503  auto *I = dyn_cast<Instruction>(V);
3504  if (!I)
3505  return nullptr;
3506 
3507  // If this is a binary operator, try to simplify it with the replaced op.
3508  if (auto *B = dyn_cast<BinaryOperator>(I)) {
3509  // Consider:
3510  // %cmp = icmp eq i32 %x, 2147483647
3511  // %add = add nsw i32 %x, 1
3512  // %sel = select i1 %cmp, i32 -2147483648, i32 %add
3513  //
3514  // We can't replace %sel with %add unless we strip away the flags.
3515  if (isa<OverflowingBinaryOperator>(B))
3516  if (B->hasNoSignedWrap() || B->hasNoUnsignedWrap())
3517  return nullptr;
3518  if (isa<PossiblyExactOperator>(B))
3519  if (B->isExact())
3520  return nullptr;
3521 
3522  if (MaxRecurse) {
3523  if (B->getOperand(0) == Op)
3524  return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), Q,
3525  MaxRecurse - 1);
3526  if (B->getOperand(1) == Op)
3527  return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, Q,
3528  MaxRecurse - 1);
3529  }
3530  }
3531 
3532  // Same for CmpInsts.
3533  if (CmpInst *C = dyn_cast<CmpInst>(I)) {
3534  if (MaxRecurse) {
3535  if (C->getOperand(0) == Op)
3536  return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), Q,
3537  MaxRecurse - 1);
3538  if (C->getOperand(1) == Op)
3539  return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, Q,
3540  MaxRecurse - 1);
3541  }
3542  }
3543 
3544  // Same for GEPs.
3545  if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
3546  if (MaxRecurse) {
3547  SmallVector<Value *, 8> NewOps(GEP->getNumOperands());
3548  transform(GEP->operands(), NewOps.begin(),
3549  [&](Value *V) { return V == Op ? RepOp : V; });
3550  return SimplifyGEPInst(GEP->getSourceElementType(), NewOps, Q,
3551  MaxRecurse - 1);
3552  }
3553  }
3554 
3555  // TODO: We could hand off more cases to instsimplify here.
3556 
3557  // If all operands are constant after substituting Op for RepOp then we can
3558  // constant fold the instruction.
3559  if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) {
3560  // Build a list of all constant operands.
3561  SmallVector<Constant *, 8> ConstOps;
3562  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
3563  if (I->getOperand(i) == Op)
3564  ConstOps.push_back(CRepOp);
3565  else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i)))
3566  ConstOps.push_back(COp);
3567  else
3568  break;
3569  }
3570 
3571  // All operands were constants, fold it.
3572  if (ConstOps.size() == I->getNumOperands()) {
3573  if (CmpInst *C = dyn_cast<CmpInst>(I))
3574  return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0],
3575  ConstOps[1], Q.DL, Q.TLI);
3576 
3577  if (LoadInst *LI = dyn_cast<LoadInst>(I))
3578  if (!LI->isVolatile())
3579  return ConstantFoldLoadFromConstPtr(ConstOps[0], LI->getType(), Q.DL);
3580 
3581  return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI);
3582  }
3583  }
3584 
3585  return nullptr;
3586 }
3587 
3588 /// Try to simplify a select instruction when its condition operand is an
3589 /// integer comparison where one operand of the compare is a constant.
3590 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X,
3591  const APInt *Y, bool TrueWhenUnset) {
3592  const APInt *C;
3593 
3594  // (X & Y) == 0 ? X & ~Y : X --> X
3595  // (X & Y) != 0 ? X & ~Y : X --> X & ~Y
3596  if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) &&
3597  *Y == ~*C)
3598  return TrueWhenUnset ? FalseVal : TrueVal;
3599 
3600  // (X & Y) == 0 ? X : X & ~Y --> X & ~Y
3601  // (X & Y) != 0 ? X : X & ~Y --> X
3602  if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) &&
3603  *Y == ~*C)
3604  return TrueWhenUnset ? FalseVal : TrueVal;
3605 
3606  if (Y->isPowerOf2()) {
3607  // (X & Y) == 0 ? X | Y : X --> X | Y
3608  // (X & Y) != 0 ? X | Y : X --> X
3609  if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) &&
3610  *Y == *C)
3611  return TrueWhenUnset ? TrueVal : FalseVal;
3612 
3613  // (X & Y) == 0 ? X : X | Y --> X
3614  // (X & Y) != 0 ? X : X | Y --> X | Y
3615  if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) &&
3616  *Y == *C)
3617  return TrueWhenUnset ? TrueVal : FalseVal;
3618  }
3619 
3620  return nullptr;
3621 }
3622 
3623 /// An alternative way to test if a bit is set or not uses sgt/slt instead of
3624 /// eq/ne.
3626  ICmpInst::Predicate Pred,
3627  Value *TrueVal, Value *FalseVal) {
3628  Value *X;
3629  APInt Mask;
3630  if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask))
3631  return nullptr;
3632 
3633  return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask,
3634  Pred == ICmpInst::ICMP_EQ);
3635 }
3636 
3637 /// Try to simplify a select instruction when its condition operand is an
3638 /// integer comparison.
3639 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
3640  Value *FalseVal, const SimplifyQuery &Q,
3641  unsigned MaxRecurse) {
3642  ICmpInst::Predicate Pred;
3643  Value *CmpLHS, *CmpRHS;
3644  if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
3645  return nullptr;
3646 
3647  if (ICmpInst::isEquality(Pred) && match(CmpRHS, m_Zero())) {
3648  Value *X;
3649  const APInt *Y;
3650  if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y))))
3651  if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y,
3652  Pred == ICmpInst::ICMP_EQ))
3653  return V;
3654  }
3655 
3656  // Check for other compares that behave like bit test.
3657  if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred,
3658  TrueVal, FalseVal))
3659  return V;
3660 
3661  // If we have an equality comparison, then we know the value in one of the
3662  // arms of the select. See if substituting this value into the arm and
3663  // simplifying the result yields the same value as the other arm.
3664  if (Pred == ICmpInst::ICMP_EQ) {
3665  if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3666  TrueVal ||
3667  SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3668  TrueVal)
3669  return FalseVal;
3670  if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3671  FalseVal ||
3672  SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3673  FalseVal)
3674  return FalseVal;
3675  } else if (Pred == ICmpInst::ICMP_NE) {
3676  if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3677  FalseVal ||
3678  SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3679  FalseVal)
3680  return TrueVal;
3681  if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3682  TrueVal ||
3683  SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3684  TrueVal)
3685  return TrueVal;
3686  }
3687 
3688  return nullptr;
3689 }
3690 
3691 /// Given operands for a SelectInst, see if we can fold the result.
3692 /// If not, this returns null.
3693 static Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3694  const SimplifyQuery &Q, unsigned MaxRecurse) {
3695  if (auto *CondC = dyn_cast<Constant>(Cond)) {
3696  if (auto *TrueC = dyn_cast<Constant>(TrueVal))
3697  if (auto *FalseC = dyn_cast<Constant>(FalseVal))
3698  return ConstantFoldSelectInstruction(CondC, TrueC, FalseC);
3699 
3700  // select undef, X, Y -> X or Y
3701  if (isa<UndefValue>(CondC))
3702  return isa<Constant>(FalseVal) ? FalseVal : TrueVal;
3703 
3704  // TODO: Vector constants with undef elements don't simplify.
3705 
3706  // select true, X, Y -> X
3707  if (CondC->isAllOnesValue())
3708  return TrueVal;
3709  // select false, X, Y -> Y
3710  if (CondC->isNullValue())
3711  return FalseVal;
3712  }
3713 
3714  // select ?, X, X -> X
3715  if (TrueVal == FalseVal)
3716  return TrueVal;
3717 
3718  if (isa<UndefValue>(TrueVal)) // select ?, undef, X -> X
3719  return FalseVal;
3720  if (isa<UndefValue>(FalseVal)) // select ?, X, undef -> X
3721  return TrueVal;
3722 
3723  if (Value *V =
3724  simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse))
3725  return V;
3726 
3727  return nullptr;
3728 }
3729 
3730 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3731  const SimplifyQuery &Q) {
3732  return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit);
3733 }
3734 
3735 /// Given operands for an GetElementPtrInst, see if we can fold the result.
3736 /// If not, this returns null.
3738  const SimplifyQuery &Q, unsigned) {
3739  // The type of the GEP pointer operand.
3740  unsigned AS =
3741  cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace();
3742 
3743  // getelementptr P -> P.
3744  if (Ops.size() == 1)
3745  return Ops[0];
3746 
3747  // Compute the (pointer) type returned by the GEP instruction.
3748  Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1));
3749  Type *GEPTy = PointerType::get(LastType, AS);
3750  if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
3751  GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3752  else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType()))
3753  GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3754 
3755  if (isa<UndefValue>(Ops[0]))
3756  return UndefValue::get(GEPTy);
3757 
3758  if (Ops.size() == 2) {
3759  // getelementptr P, 0 -> P.
3760  if (match(Ops[1], m_Zero()) && Ops[0]->getType() == GEPTy)
3761  return Ops[0];
3762 
3763  Type *Ty = SrcTy;
3764  if (Ty->isSized()) {
3765  Value *P;
3766  uint64_t C;
3767  uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty);
3768  // getelementptr P, N -> P if P points to a type of zero size.
3769  if (TyAllocSize == 0 && Ops[0]->getType() == GEPTy)
3770  return Ops[0];
3771 
3772  // The following transforms are only safe if the ptrtoint cast
3773  // doesn't truncate the pointers.
3774  if (Ops[1]->getType()->getScalarSizeInBits() ==
3775  Q.DL.getIndexSizeInBits(AS)) {
3776  auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * {
3777  if (match(P, m_Zero()))
3778  return Constant::getNullValue(GEPTy);
3779  Value *Temp;
3780  if (match(P, m_PtrToInt(m_Value(Temp))))
3781  if (Temp->getType() == GEPTy)
3782  return Temp;
3783  return nullptr;
3784  };
3785 
3786  // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
3787  if (TyAllocSize == 1 &&
3788  match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0])))))
3789  if (Value *R = PtrToIntOrZero(P))
3790  return R;
3791 
3792  // getelementptr V, (ashr (sub P, V), C) -> Q
3793  // if P points to a type of size 1 << C.
3794  if (match(Ops[1],
3795  m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3796  m_ConstantInt(C))) &&
3797  TyAllocSize == 1ULL << C)
3798  if (Value *R = PtrToIntOrZero(P))
3799  return R;
3800 
3801  // getelementptr V, (sdiv (sub P, V), C) -> Q
3802  // if P points to a type of size C.
3803  if (match(Ops[1],
3804  m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3805  m_SpecificInt(TyAllocSize))))
3806  if (Value *R = PtrToIntOrZero(P))
3807  return R;
3808  }
3809  }
3810  }
3811 
3812  if (Q.DL.getTypeAllocSize(LastType) == 1 &&
3813  all_of(Ops.slice(1).drop_back(1),
3814  [](Value *Idx) { return match(Idx, m_Zero()); })) {
3815  unsigned IdxWidth =
3816  Q.DL.getIndexSizeInBits(Ops[0]->getType()->getPointerAddressSpace());
3817  if (Q.DL.getTypeSizeInBits(Ops.back()->getType()) == IdxWidth) {
3818  APInt BasePtrOffset(IdxWidth, 0);
3819  Value *StrippedBasePtr =
3820  Ops[0]->stripAndAccumulateInBoundsConstantOffsets(Q.DL,
3821  BasePtrOffset);
3822 
3823  // gep (gep V, C), (sub 0, V) -> C
3824  if (match(Ops.back(),
3825  m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr))))) {
3826  auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset);
3827  return ConstantExpr::getIntToPtr(CI, GEPTy);
3828  }
3829  // gep (gep V, C), (xor V, -1) -> C-1
3830  if (match(Ops.back(),
3831  m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes()))) {
3832  auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1);
3833  return ConstantExpr::getIntToPtr(CI, GEPTy);
3834  }
3835  }
3836  }
3837 
3838  // Check to see if this is constant foldable.
3839  if (!all_of(Ops, [](Value *V) { return isa<Constant>(V); }))
3840  return nullptr;
3841 
3842  auto *CE = ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]),
3843  Ops.slice(1));
3844  if (auto *CEFolded = ConstantFoldConstant(CE, Q.DL))
3845  return CEFolded;
3846  return CE;
3847 }
3848 
3850  const SimplifyQuery &Q) {
3851  return ::SimplifyGEPInst(SrcTy, Ops, Q, RecursionLimit);
3852 }
3853 
3854 /// Given operands for an InsertValueInst, see if we can fold the result.
3855 /// If not, this returns null.
3857  ArrayRef<unsigned> Idxs, const SimplifyQuery &Q,
3858  unsigned) {
3859  if (Constant *CAgg = dyn_cast<Constant>(Agg))
3860  if (Constant *CVal = dyn_cast<Constant>(Val))
3861  return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
3862 
3863  // insertvalue x, undef, n -> x
3864  if (match(Val, m_Undef()))
3865  return Agg;
3866 
3867  // insertvalue x, (extractvalue y, n), n
3868  if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
3869  if (EV->getAggregateOperand()->getType() == Agg->getType() &&
3870  EV->getIndices() == Idxs) {
3871  // insertvalue undef, (extractvalue y, n), n -> y
3872  if (match(Agg, m_Undef()))
3873  return EV->getAggregateOperand();
3874 
3875  // insertvalue y, (extractvalue y, n), n -> y
3876  if (Agg == EV->getAggregateOperand())
3877  return Agg;
3878  }
3879 
3880  return nullptr;
3881 }
3882 
3884  ArrayRef<unsigned> Idxs,
3885  const SimplifyQuery &Q) {
3887 }
3888 
3890  const SimplifyQuery &Q) {
3891  // Try to constant fold.
3892  auto *VecC = dyn_cast<Constant>(Vec);
3893  auto *ValC = dyn_cast<Constant>(Val);
3894  auto *IdxC = dyn_cast<Constant>(Idx);
3895  if (VecC && ValC && IdxC)
3896  return ConstantFoldInsertElementInstruction(VecC, ValC, IdxC);
3897 
3898  // Fold into undef if index is out of bounds.
3899  if (auto *CI = dyn_cast<ConstantInt>(Idx)) {
3900  uint64_t NumElements = cast<VectorType>(Vec->getType())->getNumElements();
3901  if (CI->uge(NumElements))
3902  return UndefValue::get(Vec->getType());
3903  }
3904 
3905  // If index is undef, it might be out of bounds (see above case)
3906  if (isa<UndefValue>(Idx))
3907  return UndefValue::get(Vec->getType());
3908 
3909  return nullptr;
3910 }
3911 
3912 /// Given operands for an ExtractValueInst, see if we can fold the result.
3913 /// If not, this returns null.
3915  const SimplifyQuery &, unsigned) {
3916  if (auto *CAgg = dyn_cast<Constant>(Agg))
3917  return ConstantFoldExtractValueInstruction(CAgg, Idxs);
3918 
3919  // extractvalue x, (insertvalue y, elt, n), n -> elt
3920  unsigned NumIdxs = Idxs.size();
3921  for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr;
3922  IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) {
3923  ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices();
3924  unsigned NumInsertValueIdxs = InsertValueIdxs.size();
3925  unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs);
3926  if (InsertValueIdxs.slice(0, NumCommonIdxs) ==
3927  Idxs.slice(0, NumCommonIdxs)) {
3928  if (NumIdxs == NumInsertValueIdxs)
3929  return IVI->getInsertedValueOperand();
3930  break;
3931  }
3932  }
3933 
3934  return nullptr;
3935 }
3936 
3938  const SimplifyQuery &Q) {
3940 }
3941 
3942 /// Given operands for an ExtractElementInst, see if we can fold the result.
3943 /// If not, this returns null.
3945  unsigned) {
3946  if (auto *CVec = dyn_cast<Constant>(Vec)) {
3947  if (auto *CIdx = dyn_cast<Constant>(Idx))
3948  return ConstantFoldExtractElementInstruction(CVec, CIdx);
3949 
3950  // The index is not relevant if our vector is a splat.
3951  if (auto *Splat = CVec->getSplatValue())
3952  return Splat;
3953 
3954  if (isa<UndefValue>(Vec))
3955  return UndefValue::get(Vec->getType()->getVectorElementType());
3956  }
3957 
3958  // If extracting a specified index from the vector, see if we can recursively
3959  // find a previously computed scalar that was inserted into the vector.
3960  if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) {
3961  if (IdxC->getValue().uge(Vec->getType()->getVectorNumElements()))
3962  // definitely out of bounds, thus undefined result
3963  return UndefValue::get(Vec->getType()->getVectorElementType());
3964  if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
3965  return Elt;
3966  }
3967 
3968  // An undef extract index can be arbitrarily chosen to be an out-of-range
3969  // index value, which would result in the instruction being undef.
3970  if (isa<UndefValue>(Idx))
3971  return UndefValue::get(Vec->getType()->getVectorElementType());
3972 
3973  return nullptr;
3974 }
3975 
3977  const SimplifyQuery &Q) {
3979 }
3980 
3981 /// See if we can fold the given phi. If not, returns null.
3982 static Value *SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q) {
3983  // If all of the PHI's incoming values are the same then replace the PHI node
3984  // with the common value.
3985  Value *CommonValue = nullptr;
3986  bool HasUndefInput = false;
3987  for (Value *Incoming : PN->incoming_values()) {
3988  // If the incoming value is the phi node itself, it can safely be skipped.
3989  if (Incoming == PN) continue;
3990  if (isa<UndefValue>(Incoming)) {
3991  // Remember that we saw an undef value, but otherwise ignore them.
3992  HasUndefInput = true;
3993  continue;
3994  }
3995  if (CommonValue && Incoming != CommonValue)
3996  return nullptr; // Not the same, bail out.
3997  CommonValue = Incoming;
3998  }
3999 
4000  // If CommonValue is null then all of the incoming values were either undef or
4001  // equal to the phi node itself.
4002  if (!CommonValue)
4003  return UndefValue::get(PN->getType());
4004 
4005  // If we have a PHI node like phi(X, undef, X), where X is defined by some
4006  // instruction, we cannot return X as the result of the PHI node unless it
4007  // dominates the PHI block.
4008  if (HasUndefInput)
4009  return valueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr;
4010 
4011  return CommonValue;
4012 }
4013 
4014 static Value *SimplifyCastInst(unsigned CastOpc, Value *Op,
4015  Type *Ty, const SimplifyQuery &Q, unsigned MaxRecurse) {
4016  if (auto *C = dyn_cast<Constant>(Op))
4017  return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL);
4018 
4019  if (auto *CI = dyn_cast<CastInst>(Op)) {
4020  auto *Src = CI->getOperand(0);
4021  Type *SrcTy = Src->getType();
4022  Type *MidTy = CI->getType();
4023  Type *DstTy = Ty;
4024  if (Src->getType() == Ty) {
4025  auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode());
4026  auto SecondOp = static_cast<Instruction::CastOps>(CastOpc);
4027  Type *SrcIntPtrTy =
4028  SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr;
4029  Type *MidIntPtrTy =
4030  MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr;
4031  Type *DstIntPtrTy =
4032  DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr;
4033  if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy,
4034  SrcIntPtrTy, MidIntPtrTy,
4035  DstIntPtrTy) == Instruction::BitCast)
4036  return Src;
4037  }
4038  }
4039 
4040  // bitcast x -> x
4041  if (CastOpc == Instruction::BitCast)
4042  if (Op->getType() == Ty)
4043  return Op;
4044 
4045  return nullptr;
4046 }
4047 
4048 Value *llvm::SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
4049  const SimplifyQuery &Q) {
4050  return ::SimplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit);
4051 }
4052 
4053 /// For the given destination element of a shuffle, peek through shuffles to
4054 /// match a root vector source operand that contains that element in the same
4055 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s).
4056 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1,
4057  int MaskVal, Value *RootVec,
4058  unsigned MaxRecurse) {
4059  if (!MaxRecurse--)
4060  return nullptr;
4061 
4062  // Bail out if any mask value is undefined. That kind of shuffle may be
4063  // simplified further based on demanded bits or other folds.
4064  if (MaskVal == -1)
4065  return nullptr;
4066 
4067  // The mask value chooses which source operand we need to look at next.
4068  int InVecNumElts = Op0->getType()->getVectorNumElements();
4069  int RootElt = MaskVal;
4070  Value *SourceOp = Op0;
4071  if (MaskVal >= InVecNumElts) {
4072  RootElt = MaskVal - InVecNumElts;
4073  SourceOp = Op1;
4074  }
4075 
4076  // If the source operand is a shuffle itself, look through it to find the
4077  // matching root vector.
4078  if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) {
4079  return foldIdentityShuffles(
4080  DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1),
4081  SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse);
4082  }
4083 
4084  // TODO: Look through bitcasts? What if the bitcast changes the vector element
4085  // size?
4086 
4087  // The source operand is not a shuffle. Initialize the root vector value for
4088  // this shuffle if that has not been done yet.
4089  if (!RootVec)
4090  RootVec = SourceOp;
4091 
4092  // Give up as soon as a source operand does not match the existing root value.
4093  if (RootVec != SourceOp)
4094  return nullptr;
4095 
4096  // The element must be coming from the same lane in the source vector
4097  // (although it may have crossed lanes in intermediate shuffles).
4098  if (RootElt != DestElt)
4099  return nullptr;
4100 
4101  return RootVec;
4102 }
4103 
4105  Type *RetTy, const SimplifyQuery &Q,
4106  unsigned MaxRecurse) {
4107  if (isa<UndefValue>(Mask))
4108  return UndefValue::get(RetTy);
4109 
4110  Type *InVecTy = Op0->getType();
4111  unsigned MaskNumElts = Mask->getType()->getVectorNumElements();
4112  unsigned InVecNumElts = InVecTy->getVectorNumElements();
4113 
4114  SmallVector<int, 32> Indices;
4115  ShuffleVectorInst::getShuffleMask(Mask, Indices);
4116  assert(MaskNumElts == Indices.size() &&
4117  "Size of Indices not same as number of mask elements?");
4118 
4119  // Canonicalization: If mask does not select elements from an input vector,
4120  // replace that input vector with undef.
4121  bool MaskSelects0 = false, MaskSelects1 = false;
4122  for (unsigned i = 0; i != MaskNumElts; ++i) {
4123  if (Indices[i] == -1)
4124  continue;
4125  if ((unsigned)Indices[i] < InVecNumElts)
4126  MaskSelects0 = true;
4127  else
4128  MaskSelects1 = true;
4129  }
4130  if (!MaskSelects0)
4131  Op0 = UndefValue::get(InVecTy);
4132  if (!MaskSelects1)
4133  Op1 = UndefValue::get(InVecTy);
4134 
4135  auto *Op0Const = dyn_cast<Constant>(Op0);
4136  auto *Op1Const = dyn_cast<Constant>(Op1);
4137 
4138  // If all operands are constant, constant fold the shuffle.
4139  if (Op0Const && Op1Const)
4140  return ConstantFoldShuffleVectorInstruction(Op0Const, Op1Const, Mask);
4141 
4142  // Canonicalization: if only one input vector is constant, it shall be the
4143  // second one.
4144  if (Op0Const && !Op1Const) {
4145  std::swap(Op0, Op1);
4146  ShuffleVectorInst::commuteShuffleMask(Indices, InVecNumElts);
4147  }
4148 
4149  // A shuffle of a splat is always the splat itself. Legal if the shuffle's
4150  // value type is same as the input vectors' type.
4151  if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0))
4152  if (isa<UndefValue>(Op1) && RetTy == InVecTy &&
4153  OpShuf->getMask()->getSplatValue())
4154  return Op0;
4155 
4156  // Don't fold a shuffle with undef mask elements. This may get folded in a
4157  // better way using demanded bits or other analysis.
4158  // TODO: Should we allow this?
4159  if (find(Indices, -1) != Indices.end())
4160  return nullptr;
4161 
4162  // Check if every element of this shuffle can be mapped back to the
4163  // corresponding element of a single root vector. If so, we don't need this
4164  // shuffle. This handles simple identity shuffles as well as chains of
4165  // shuffles that may widen/narrow and/or move elements across lanes and back.
4166  Value *RootVec = nullptr;
4167  for (unsigned i = 0; i != MaskNumElts; ++i) {
4168  // Note that recursion is limited for each vector element, so if any element
4169  // exceeds the limit, this will fail to simplify.
4170  RootVec =
4171  foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse);
4172 
4173  // We can't replace a widening/narrowing shuffle with one of its operands.
4174  if (!RootVec || RootVec->getType() != RetTy)
4175  return nullptr;
4176  }
4177  return RootVec;
4178 }
4179 
4180 /// Given operands for a ShuffleVectorInst, fold the result or return null.
4182  Type *RetTy, const SimplifyQuery &Q) {
4183  return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit);
4184 }
4185 
4187  // If the input is a vector with undef elements, just return a default NaN.
4188  if (!In->isNaN())
4189  return ConstantFP::getNaN(In->getType());
4190 
4191  // Propagate the existing NaN constant when possible.
4192  // TODO: Should we quiet a signaling NaN?
4193  return In;
4194 }
4195 
4196 static Constant *simplifyFPBinop(Value *Op0, Value *Op1) {
4197  if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1))
4198  return ConstantFP::getNaN(Op0->getType());
4199 
4200  if (match(Op0, m_NaN()))
4201  return propagateNaN(cast<Constant>(Op0));
4202  if (match(Op1, m_NaN()))
4203  return propagateNaN(cast<Constant>(Op1));
4204 
4205  return nullptr;
4206 }
4207 
4208 /// Given operands for an FAdd, see if we can fold the result. If not, this
4209 /// returns null.
4211  const SimplifyQuery &Q, unsigned MaxRecurse) {
4212  if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q))
4213  return C;
4214 
4215  if (Constant *C = simplifyFPBinop(Op0, Op1))
4216  return C;
4217 
4218  // fadd X, -0 ==> X
4219  if (match(Op1, m_NegZeroFP()))
4220  return Op0;
4221 
4222  // fadd X, 0 ==> X, when we know X is not -0
4223  if (match(Op1, m_PosZeroFP()) &&
4224  (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
4225  return Op0;
4226 
4227  // With nnan: (+/-0.0 - X) + X --> 0.0 (and commuted variant)
4228  // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN.
4229  // Negative zeros are allowed because we always end up with positive zero:
4230  // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0
4231  // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0
4232  // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0
4233  // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0
4234  if (FMF.noNaNs() && (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) ||
4235  match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0)))))
4236  return ConstantFP::getNullValue(Op0->getType());
4237 
4238  return nullptr;
4239 }
4240 
4241 /// Given operands for an FSub, see if we can fold the result. If not, this
4242 /// returns null.
4244  const SimplifyQuery &Q, unsigned MaxRecurse) {
4245  if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q))
4246  return C;
4247 
4248  if (Constant *C = simplifyFPBinop(Op0, Op1))
4249  return C;
4250 
4251  // fsub X, +0 ==> X
4252  if (match(Op1, m_PosZeroFP()))
4253  return Op0;
4254 
4255  // fsub X, -0 ==> X, when we know X is not -0
4256  if (match(Op1, m_NegZeroFP()) &&
4257  (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
4258  return Op0;
4259 
4260  // fsub -0.0, (fsub -0.0, X) ==> X
4261  Value *X;
4262  if (match(Op0, m_NegZeroFP()) &&
4263  match(Op1, m_FSub(m_NegZeroFP(), m_Value(X))))
4264  return X;
4265 
4266  // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.
4267  if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) &&
4268  match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))))
4269  return X;
4270 
4271  // fsub nnan x, x ==> 0.0
4272  if (FMF.noNaNs() && Op0 == Op1)
4273  return Constant::getNullValue(Op0->getType());
4274 
4275  return nullptr;
4276 }
4277 
4278 /// Given the operands for an FMul, see if we can fold the result
4280  const SimplifyQuery &Q, unsigned MaxRecurse) {
4281  if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q))
4282  return C;
4283 
4284  if (Constant *C = simplifyFPBinop(Op0, Op1))
4285  return C;
4286 
4287  // fmul X, 1.0 ==> X
4288  if (match(Op1, m_FPOne()))
4289  return Op0;
4290 
4291  // fmul nnan nsz X, 0 ==> 0
4292  if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZeroFP()))
4293  return ConstantFP::getNullValue(Op0->getType());
4294 
4295  // sqrt(X) * sqrt(X) --> X, if we can:
4296  // 1. Remove the intermediate rounding (reassociate).
4297  // 2. Ignore non-zero negative numbers because sqrt would produce NAN.
4298  // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0.
4299  Value *X;
4300  if (Op0 == Op1 && match(Op0, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))) &&
4301  FMF.allowReassoc() && FMF.noNaNs() && FMF.noSignedZeros())
4302  return X;
4303 
4304  return nullptr;
4305 }
4306 
4308  const SimplifyQuery &Q) {
4309  return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit);
4310 }
4311 
4312 
4314  const SimplifyQuery &Q) {
4315  return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit);
4316 }
4317 
4319  const SimplifyQuery &Q) {
4320  return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit);
4321 }
4322 
4324  const SimplifyQuery &Q, unsigned) {
4325  if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q))
4326  return C;
4327 
4328  if (Constant *C = simplifyFPBinop(Op0, Op1))
4329  return C;
4330 
4331  // X / 1.0 -> X
4332  if (match(Op1, m_FPOne()))
4333  return Op0;
4334 
4335  // 0 / X -> 0
4336  // Requires that NaNs are off (X could be zero) and signed zeroes are
4337  // ignored (X could be positive or negative, so the output sign is unknown).
4338  if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()))
4339  return ConstantFP::getNullValue(Op0->getType());
4340 
4341  if (FMF.noNaNs()) {
4342  // X / X -> 1.0 is legal when NaNs are ignored.
4343  // We can ignore infinities because INF/INF is NaN.
4344  if (Op0 == Op1)
4345  return ConstantFP::get(Op0->getType(), 1.0);
4346 
4347  // (X * Y) / Y --> X if we can reassociate to the above form.
4348  Value *X;
4349  if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1))))
4350  return X;
4351 
4352  // -X / X -> -1.0 and
4353  // X / -X -> -1.0 are legal when NaNs are ignored.
4354  // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored.
4355  if ((BinaryOperator::isFNeg(Op0, /*IgnoreZeroSign=*/true) &&
4356  BinaryOperator::getFNegArgument(Op0) == Op1) ||
4357  (BinaryOperator::isFNeg(Op1, /*IgnoreZeroSign=*/true) &&
4358  BinaryOperator::getFNegArgument(Op1) == Op0))
4359  return ConstantFP::get(Op0->getType(), -1.0);
4360  }
4361 
4362  return nullptr;
4363 }
4364 
4366  const SimplifyQuery &Q) {
4367  return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit);
4368 }
4369 
4371  const SimplifyQuery &Q, unsigned) {
4372  if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q))
4373  return C;
4374 
4375  if (Constant *C = simplifyFPBinop(Op0, Op1))
4376  return C;
4377 
4378  // Unlike fdiv, the result of frem always matches the sign of the dividend.
4379  // The constant match may include undef elements in a vector, so return a full
4380  // zero constant as the result.
4381  if (FMF.noNaNs()) {
4382  // +0 % X -> 0
4383  if (match(Op0, m_PosZeroFP()))
4384  return ConstantFP::getNullValue(Op0->getType());
4385  // -0 % X -> -0
4386  if (match(Op0, m_NegZeroFP()))
4387  return ConstantFP::getNegativeZero(Op0->getType());
4388  }
4389 
4390  return nullptr;
4391 }
4392 
4394  const SimplifyQuery &Q) {
4395  return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit);
4396 }
4397 
4398 //=== Helper functions for higher up the class hierarchy.
4399 
4400 /// Given operands for a BinaryOperator, see if we can fold the result.
4401 /// If not, this returns null.
4402 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4403  const SimplifyQuery &Q, unsigned MaxRecurse) {
4404  switch (Opcode) {
4405  case Instruction::Add:
4406  return SimplifyAddInst(LHS, RHS, false, false, Q, MaxRecurse);
4407  case Instruction::Sub:
4408  return SimplifySubInst(LHS, RHS, false, false, Q, MaxRecurse);
4409  case Instruction::Mul:
4410  return SimplifyMulInst(LHS, RHS, Q, MaxRecurse);
4411  case Instruction::SDiv:
4412  return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
4413  case Instruction::UDiv:
4414  return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
4415  case Instruction::SRem:
4416  return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
4417  case Instruction::URem:
4418  return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
4419  case Instruction::Shl:
4420  return SimplifyShlInst(LHS, RHS, false, false, Q, MaxRecurse);
4421  case Instruction::LShr:
4422  return SimplifyLShrInst(LHS, RHS, false, Q, MaxRecurse);
4423  case Instruction::AShr:
4424  return SimplifyAShrInst(LHS, RHS, false, Q, MaxRecurse);
4425  case Instruction::And:
4426  return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
4427  case Instruction::Or:
4428  return SimplifyOrInst(LHS, RHS, Q, MaxRecurse);
4429  case Instruction::Xor:
4430  return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
4431  case Instruction::FAdd:
4432  return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4433  case Instruction::FSub:
4434  return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4435  case Instruction::FMul:
4436  return SimplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4437  case Instruction::FDiv:
4438  return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4439  case Instruction::FRem:
4440  return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4441  default:
4442  llvm_unreachable("Unexpected opcode");
4443  }
4444 }
4445 
4446 /// Given operands for a BinaryOperator, see if we can fold the result.
4447 /// If not, this returns null.
4448 /// In contrast to SimplifyBinOp, try to use FastMathFlag when folding the
4449 /// result. In case we don't need FastMathFlags, simply fall to SimplifyBinOp.
4450 static Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4451  const FastMathFlags &FMF, const SimplifyQuery &Q,
4452  unsigned MaxRecurse) {
4453  switch (Opcode) {
4454  case Instruction::FAdd:
4455  return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse);
4456  case Instruction::FSub:
4457  return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse);
4458  case Instruction::FMul:
4459  return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse);
4460  case Instruction::FDiv:
4461  return SimplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse);
4462  default:
4463  return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
4464  }
4465 }
4466 
4467 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4468  const SimplifyQuery &Q) {
4469  return ::SimplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit);
4470 }
4471 
4472 Value *llvm::SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4473  FastMathFlags FMF, const SimplifyQuery &Q) {
4474  return ::SimplifyFPBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit);
4475 }
4476 
4477 /// Given operands for a CmpInst, see if we can fold the result.
4478 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
4479  const SimplifyQuery &Q, unsigned MaxRecurse) {
4481  return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
4482  return SimplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4483 }
4484 
4485 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
4486  const SimplifyQuery &Q) {
4487  return ::SimplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
4488 }
4489 
4491  switch (ID) {
4492  default: return false;
4493 
4494  // Unary idempotent: f(f(x)) = f(x)
4495  case Intrinsic::fabs:
4496  case Intrinsic::floor:
4497  case Intrinsic::ceil:
4498  case Intrinsic::trunc:
4499  case Intrinsic::rint:
4500  case Intrinsic::nearbyint:
4501  case Intrinsic::round:
4502  case Intrinsic::canonicalize:
4503  return true;
4504  }
4505 }
4506 
4508  const DataLayout &DL) {
4509  GlobalValue *PtrSym;
4510  APInt PtrOffset;
4511  if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL))
4512  return nullptr;
4513 
4514  Type *Int8PtrTy = Type::getInt8PtrTy(Ptr->getContext());
4516  Type *Int32PtrTy = Int32Ty->getPointerTo();
4517  Type *Int64Ty = Type::getInt64Ty(Ptr->getContext());
4518 
4519  auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset);
4520  if (!OffsetConstInt || OffsetConstInt->getType()->getBitWidth() > 64)
4521  return nullptr;
4522 
4523  uint64_t OffsetInt = OffsetConstInt->getSExtValue();
4524  if (OffsetInt % 4 != 0)
4525  return nullptr;
4526 
4528  Int32Ty, ConstantExpr::getBitCast(Ptr, Int32PtrTy),
4529  ConstantInt::get(Int64Ty, OffsetInt / 4));
4530  Constant *Loaded = ConstantFoldLoadFromConstPtr(C, Int32Ty, DL);
4531  if (!Loaded)
4532  return nullptr;
4533 
4534  auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded);
4535  if (!LoadedCE)
4536  return nullptr;
4537 
4538  if (LoadedCE->getOpcode() == Instruction::Trunc) {
4539  LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
4540  if (!LoadedCE)
4541  return nullptr;
4542  }
4543 
4544  if (LoadedCE->getOpcode() != Instruction::Sub)
4545  return nullptr;
4546 
4547  auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
4548  if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt)
4549  return nullptr;
4550  auto *LoadedLHSPtr = LoadedLHS->getOperand(0);
4551 
4552  Constant *LoadedRHS = LoadedCE->getOperand(1);
4553  GlobalValue *LoadedRHSSym;
4554  APInt LoadedRHSOffset;
4555  if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset,
4556  DL) ||
4557  PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset)
4558  return nullptr;
4559 
4560  return ConstantExpr::getBitCast(LoadedLHSPtr, Int8PtrTy);
4561 }
4562 
4564  auto *ConstMask = dyn_cast<Constant>(Mask);
4565  if (!ConstMask)
4566  return false;
4567  if (ConstMask->isNullValue() || isa<UndefValue>(ConstMask))
4568  return true;
4569  for (unsigned I = 0, E = ConstMask->getType()->getVectorNumElements(); I != E;
4570  ++I) {
4571  if (auto *MaskElt = ConstMask->getAggregateElement(I))
4572  if (MaskElt->isNullValue() || isa<UndefValue>(MaskElt))
4573  continue;
4574  return false;
4575  }
4576  return true;
4577 }
4578 
4579 template <typename IterTy>
4580 static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
4581  const SimplifyQuery &Q, unsigned MaxRecurse) {
4582  Intrinsic::ID IID = F->getIntrinsicID();
4583  unsigned NumOperands = std::distance(ArgBegin, ArgEnd);
4584 
4585  // Unary Ops
4586  if (NumOperands == 1) {
4587  // Perform idempotent optimizations
4588  if (IsIdempotent(IID)) {
4589  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin)) {
4590  if (II->getIntrinsicID() == IID)
4591  return II;
4592  }
4593  }
4594 
4595  Value *IIOperand = *ArgBegin;
4596  Value *X;
4597  switch (IID) {
4598  case Intrinsic::fabs: {
4599  if (SignBitMustBeZero(IIOperand, Q.TLI))
4600  return IIOperand;
4601  return nullptr;
4602  }
4603  case Intrinsic::bswap: {
4604  // bswap(bswap(x)) -> x
4605  if (match(IIOperand, m_BSwap(m_Value(X))))
4606  return X;
4607  return nullptr;
4608  }
4609  case Intrinsic::bitreverse: {
4610  // bitreverse(bitreverse(x)) -> x
4611  if (match(IIOperand, m_BitReverse(m_Value(X))))
4612  return X;
4613  return nullptr;
4614  }
4615  case Intrinsic::exp: {
4616  // exp(log(x)) -> x
4617  if (Q.CxtI->hasAllowReassoc() &&
4618  match(IIOperand, m_Intrinsic<Intrinsic::log>(m_Value(X))))
4619  return X;
4620  return nullptr;
4621  }
4622  case Intrinsic::exp2: {
4623  // exp2(log2(x)) -> x
4624  if (Q.CxtI->hasAllowReassoc() &&
4625  match(IIOperand, m_Intrinsic<Intrinsic::log2>(m_Value(X))))
4626  return X;
4627  return nullptr;
4628  }
4629  case Intrinsic::log: {
4630  // log(exp(x)) -> x
4631  if (Q.CxtI->hasAllowReassoc() &&
4632  match(IIOperand, m_Intrinsic<Intrinsic::exp>(m_Value(X))))
4633  return X;
4634  return nullptr;
4635  }
4636  case Intrinsic::log2: {
4637  // log2(exp2(x)) -> x
4638  if (Q.CxtI->hasAllowReassoc() &&
4639  match(IIOperand, m_Intrinsic<Intrinsic::exp2>(m_Value(X)))) {
4640  return X;
4641  }
4642  return nullptr;
4643  }
4644  default:
4645  return nullptr;
4646  }
4647  }
4648 
4649  // Binary Ops
4650  if (NumOperands == 2) {
4651  Value *LHS = *ArgBegin;
4652  Value *RHS = *(ArgBegin + 1);
4653  Type *ReturnType = F->getReturnType();
4654 
4655  switch (IID) {
4656  case Intrinsic::usub_with_overflow:
4657  case Intrinsic::ssub_with_overflow: {
4658  // X - X -> { 0, false }
4659  if (LHS == RHS)
4660  return Constant::getNullValue(ReturnType);
4661 
4662  // X - undef -> undef
4663  // undef - X -> undef
4664  if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS))
4665  return UndefValue::get(ReturnType);
4666 
4667  return nullptr;
4668  }
4669  case Intrinsic::uadd_with_overflow:
4670  case Intrinsic::sadd_with_overflow: {
4671  // X + undef -> undef
4672  if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS))
4673  return UndefValue::get(ReturnType);
4674 
4675  return nullptr;
4676  }
4677  case Intrinsic::umul_with_overflow:
4678  case Intrinsic::smul_with_overflow: {
4679  // 0 * X -> { 0, false }
4680  // X * 0 -> { 0, false }
4681  if (match(LHS, m_Zero()) || match(RHS, m_Zero()))
4682  return Constant::getNullValue(ReturnType);
4683 
4684  // undef * X -> { 0, false }
4685  // X * undef -> { 0, false }
4686  if (match(LHS, m_Undef()) || match(RHS, m_Undef()))
4687  return Constant::getNullValue(ReturnType);
4688 
4689  return nullptr;
4690  }
4691  case Intrinsic::load_relative: {
4692  Constant *C0 = dyn_cast<Constant>(LHS);
4693  Constant *C1 = dyn_cast<Constant>(RHS);
4694  if (C0 && C1)
4695  return SimplifyRelativeLoad(C0, C1, Q.DL);
4696  return nullptr;
4697  }
4698  case Intrinsic::powi:
4699  if (ConstantInt *Power = dyn_cast<ConstantInt>(RHS)) {
4700  // powi(x, 0) -> 1.0
4701  if (Power->isZero())
4702  return ConstantFP::get(LHS->getType(), 1.0);
4703  // powi(x, 1) -> x
4704  if (Power->isOne())
4705  return LHS;
4706  }
4707  return nullptr;
4708  default:
4709  return nullptr;
4710  }
4711  }
4712 
4713  // Simplify calls to llvm.masked.load.*
4714  switch (IID) {
4715  case Intrinsic::masked_load: {
4716  Value *MaskArg = ArgBegin[2];
4717  Value *PassthruArg = ArgBegin[3];
4718  // If the mask is all zeros or undef, the "passthru" argument is the result.
4719  if (maskIsAllZeroOrUndef(MaskArg))
4720  return PassthruArg;
4721  return nullptr;
4722  }
4723  default:
4724  return nullptr;
4725  }
4726 }
4727 
4728 template <typename IterTy>
4729 static Value *SimplifyCall(ImmutableCallSite CS, Value *V, IterTy ArgBegin,
4730  IterTy ArgEnd, const SimplifyQuery &Q,
4731  unsigned MaxRecurse) {
4732  Type *Ty = V->getType();
4733  if (PointerType *PTy = dyn_cast<PointerType>(Ty))
4734  Ty = PTy->getElementType();
4735  FunctionType *FTy = cast<FunctionType>(Ty);
4736 
4737  // call undef -> undef
4738  // call null -> undef
4739  if (isa<UndefValue>(V) || isa<ConstantPointerNull>(V))
4740  return UndefValue::get(FTy->getReturnType());
4741 
4742  Function *F = dyn_cast<Function>(V);
4743  if (!F)
4744  return nullptr;
4745 
4746  if (F->isIntrinsic())
4747  if (Value *Ret = SimplifyIntrinsic(F, ArgBegin, ArgEnd, Q, MaxRecurse))
4748  return Ret;
4749 
4750  if (!canConstantFoldCallTo(CS, F))
4751  return nullptr;
4752 
4753  SmallVector<Constant *, 4> ConstantArgs;
4754  ConstantArgs.reserve(ArgEnd - ArgBegin);
4755  for (IterTy I = ArgBegin, E = ArgEnd; I != E; ++I) {
4756  Constant *C = dyn_cast<Constant>(*I);
4757  if (!C)
4758  return nullptr;
4759  ConstantArgs.push_back(C);
4760  }
4761 
4762  return ConstantFoldCall(CS, F, ConstantArgs, Q.TLI);
4763 }
4764 
4766  User::op_iterator ArgBegin, User::op_iterator ArgEnd,
4767  const SimplifyQuery &Q) {
4768  return ::SimplifyCall(CS, V, ArgBegin, ArgEnd, Q, RecursionLimit);
4769 }
4770 
4772  ArrayRef<Value *> Args, const SimplifyQuery &Q) {
4773  return ::SimplifyCall(CS, V, Args.begin(), Args.end(), Q, RecursionLimit);
4774 }
4775 
4777  CallSite CS(const_cast<Instruction*>(ICS.getInstruction()));
4779  Q, RecursionLimit);
4780 }
4781 
4782 /// See if we can compute a simplified version of this instruction.
4783 /// If not, this returns null.
4784 
4787  const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I);
4788  Value *Result;
4789 
4790  switch (I->getOpcode()) {
4791  default:
4792  Result = ConstantFoldInstruction(I, Q.DL, Q.TLI);
4793  break;
4794  case Instruction::FAdd:
4795  Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
4796  I->getFastMathFlags(), Q);
4797  break;
4798  case Instruction::Add:
4799  Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
4800  cast<BinaryOperator>(I)->hasNoSignedWrap(),
4801  cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4802  break;
4803  case Instruction::FSub:
4804  Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
4805  I->getFastMathFlags(), Q);
4806  break;
4807  case Instruction::Sub:
4808  Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
4809  cast<BinaryOperator>(I)->hasNoSignedWrap(),
4810  cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4811  break;
4812  case Instruction::FMul:
4813  Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1),
4814  I->getFastMathFlags(), Q);
4815  break;
4816  case Instruction::Mul:
4817  Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), Q);
4818  break;
4819  case Instruction::SDiv:
4820  Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), Q);
4821  break;
4822  case Instruction::UDiv:
4823  Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), Q);
4824  break;
4825  case Instruction::FDiv:
4826  Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1),
4827  I->getFastMathFlags(), Q);
4828  break;
4829  case Instruction::SRem:
4830  Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), Q);
4831  break;
4832  case Instruction::URem:
4833  Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), Q);
4834  break;
4835  case Instruction::FRem:
4836  Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1),
4837  I->getFastMathFlags(), Q);
4838  break;
4839  case Instruction::Shl:
4840  Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
4841  cast<BinaryOperator>(I)->hasNoSignedWrap(),
4842  cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4843  break;
4844  case Instruction::LShr:
4845  Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
4846  cast<BinaryOperator>(I)->isExact(), Q);
4847  break;
4848  case Instruction::AShr:
4849  Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
4850  cast<BinaryOperator>(I)->isExact(), Q);
4851  break;
4852  case Instruction::And:
4853  Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), Q);
4854  break;
4855  case Instruction::Or:
4856  Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), Q);
4857  break;
4858  case Instruction::Xor:
4859  Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), Q);
4860  break;
4861  case Instruction::ICmp:
4862  Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
4863  I->getOperand(0), I->getOperand(1), Q);
4864  break;
4865  case Instruction::FCmp:
4866  Result =
4867  SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0),
4868  I->getOperand(1), I->getFastMathFlags(), Q);
4869  break;
4870  case Instruction::Select:
4871  Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
4872  I->getOperand(2), Q);
4873  break;
4874  case Instruction::GetElementPtr: {
4875  SmallVector<Value *, 8> Ops(I->op_begin(), I->