1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements routines for folding instructions into simpler forms
11 // that do not require creating new instructions.  This does constant folding
12 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
13 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
14 // ("and i32 %x, %x" -> "%x").  All operands are assumed to have already been
15 // simplified: This is usually true and assuming it simplifies the logic (if
16 // they have not been simplified then results are correct but maybe suboptimal).
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #include "llvm/Analysis/InstructionSimplify.h"
21 #include "llvm/ADT/SetVector.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/Analysis/AliasAnalysis.h"
24 #include "llvm/Analysis/AssumptionCache.h"
25 #include "llvm/Analysis/CaptureTracking.h"
26 #include "llvm/Analysis/ConstantFolding.h"
27 #include "llvm/Analysis/LoopAnalysisManager.h"
28 #include "llvm/Analysis/MemoryBuiltins.h"
29 #include "llvm/Analysis/OptimizationDiagnosticInfo.h"
30 #include "llvm/Analysis/ValueTracking.h"
31 #include "llvm/Analysis/VectorUtils.h"
32 #include "llvm/IR/ConstantRange.h"
33 #include "llvm/IR/DataLayout.h"
34 #include "llvm/IR/Dominators.h"
35 #include "llvm/IR/GetElementPtrTypeIterator.h"
36 #include "llvm/IR/GlobalAlias.h"
37 #include "llvm/IR/Operator.h"
38 #include "llvm/IR/PatternMatch.h"
39 #include "llvm/IR/ValueHandle.h"
40 #include "llvm/Support/KnownBits.h"
41 #include <algorithm>
42 using namespace llvm;
43 using namespace llvm::PatternMatch;
44 
45 #define DEBUG_TYPE "instsimplify"
46 
47 enum { RecursionLimit = 3 };
48 
49 STATISTIC(NumExpand,  "Number of expansions");
50 STATISTIC(NumReassoc, "Number of reassociations");
51 
52 static Value *SimplifyAndInst(Value *, Value *, const SimplifyQuery &, unsigned);
53 static Value *SimplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &,
54                             unsigned);
55 static Value *SimplifyFPBinOp(unsigned, Value *, Value *, const FastMathFlags &,
56                               const SimplifyQuery &, unsigned);
57 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &,
58                               unsigned);
59 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
60                                const SimplifyQuery &Q, unsigned MaxRecurse);
61 static Value *SimplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned);
62 static Value *SimplifyXorInst(Value *, Value *, const SimplifyQuery &, unsigned);
63 static Value *SimplifyCastInst(unsigned, Value *, Type *,
64                                const SimplifyQuery &, unsigned);
65 
66 /// For a boolean type or a vector of boolean type, return false or a vector
67 /// with every element false.
68 static Constant *getFalse(Type *Ty) {
69   return ConstantInt::getFalse(Ty);
70 }
71 
72 /// For a boolean type or a vector of boolean type, return true or a vector
73 /// with every element true.
74 static Constant *getTrue(Type *Ty) {
75   return ConstantInt::getTrue(Ty);
76 }
77 
78 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
79 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
80                           Value *RHS) {
81   CmpInst *Cmp = dyn_cast<CmpInst>(V);
82   if (!Cmp)
83     return false;
84   CmpInst::Predicate CPred = Cmp->getPredicate();
85   Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
86   if (CPred == Pred && CLHS == LHS && CRHS == RHS)
87     return true;
88   return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
89     CRHS == LHS;
90 }
91 
92 /// Does the given value dominate the specified phi node?
93 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
94   Instruction *I = dyn_cast<Instruction>(V);
95   if (!I)
96     // Arguments and constants dominate all instructions.
97     return true;
98 
99   // If we are processing instructions (and/or basic blocks) that have not been
100   // fully added to a function, the parent nodes may still be null. Simply
101   // return the conservative answer in these cases.
102   if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
103     return false;
104 
105   // If we have a DominatorTree then do a precise test.
106   if (DT) {
107     if (!DT->isReachableFromEntry(P->getParent()))
108       return true;
109     if (!DT->isReachableFromEntry(I->getParent()))
110       return false;
111     return DT->dominates(I, P);
112   }
113 
114   // Otherwise, if the instruction is in the entry block and is not an invoke,
115   // then it obviously dominates all phi nodes.
116   if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
117       !isa<InvokeInst>(I))
118     return true;
119 
120   return false;
121 }
122 
123 /// Simplify "A op (B op' C)" by distributing op over op', turning it into
124 /// "(A op B) op' (A op C)".  Here "op" is given by Opcode and "op'" is
125 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
126 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
127 /// Returns the simplified value, or null if no simplification was performed.
128 static Value *ExpandBinOp(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS,
129                           Instruction::BinaryOps OpcodeToExpand, const SimplifyQuery &Q,
130                           unsigned MaxRecurse) {
131   // Recursion is always used, so bail out at once if we already hit the limit.
132   if (!MaxRecurse--)
133     return nullptr;
134 
135   // Check whether the expression has the form "(A op' B) op C".
136   if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
137     if (Op0->getOpcode() == OpcodeToExpand) {
138       // It does!  Try turning it into "(A op C) op' (B op C)".
139       Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
140       // Do "A op C" and "B op C" both simplify?
141       if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
142         if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
143           // They do! Return "L op' R" if it simplifies or is already available.
144           // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
145           if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
146                                      && L == B && R == A)) {
147             ++NumExpand;
148             return LHS;
149           }
150           // Otherwise return "L op' R" if it simplifies.
151           if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
152             ++NumExpand;
153             return V;
154           }
155         }
156     }
157 
158   // Check whether the expression has the form "A op (B op' C)".
159   if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
160     if (Op1->getOpcode() == OpcodeToExpand) {
161       // It does!  Try turning it into "(A op B) op' (A op C)".
162       Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
163       // Do "A op B" and "A op C" both simplify?
164       if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
165         if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
166           // They do! Return "L op' R" if it simplifies or is already available.
167           // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
168           if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
169                                      && L == C && R == B)) {
170             ++NumExpand;
171             return RHS;
172           }
173           // Otherwise return "L op' R" if it simplifies.
174           if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
175             ++NumExpand;
176             return V;
177           }
178         }
179     }
180 
181   return nullptr;
182 }
183 
184 /// Generic simplifications for associative binary operations.
185 /// Returns the simpler value, or null if none was found.
186 static Value *SimplifyAssociativeBinOp(Instruction::BinaryOps Opcode,
187                                        Value *LHS, Value *RHS, const SimplifyQuery &Q,
188                                        unsigned MaxRecurse) {
189   assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
190 
191   // Recursion is always used, so bail out at once if we already hit the limit.
192   if (!MaxRecurse--)
193     return nullptr;
194 
195   BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
196   BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
197 
198   // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
199   if (Op0 && Op0->getOpcode() == Opcode) {
200     Value *A = Op0->getOperand(0);
201     Value *B = Op0->getOperand(1);
202     Value *C = RHS;
203 
204     // Does "B op C" simplify?
205     if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
206       // It does!  Return "A op V" if it simplifies or is already available.
207       // If V equals B then "A op V" is just the LHS.
208       if (V == B) return LHS;
209       // Otherwise return "A op V" if it simplifies.
210       if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
211         ++NumReassoc;
212         return W;
213       }
214     }
215   }
216 
217   // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
218   if (Op1 && Op1->getOpcode() == Opcode) {
219     Value *A = LHS;
220     Value *B = Op1->getOperand(0);
221     Value *C = Op1->getOperand(1);
222 
223     // Does "A op B" simplify?
224     if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
225       // It does!  Return "V op C" if it simplifies or is already available.
226       // If V equals B then "V op C" is just the RHS.
227       if (V == B) return RHS;
228       // Otherwise return "V op C" if it simplifies.
229       if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
230         ++NumReassoc;
231         return W;
232       }
233     }
234   }
235 
236   // The remaining transforms require commutativity as well as associativity.
237   if (!Instruction::isCommutative(Opcode))
238     return nullptr;
239 
240   // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
241   if (Op0 && Op0->getOpcode() == Opcode) {
242     Value *A = Op0->getOperand(0);
243     Value *B = Op0->getOperand(1);
244     Value *C = RHS;
245 
246     // Does "C op A" simplify?
247     if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
248       // It does!  Return "V op B" if it simplifies or is already available.
249       // If V equals A then "V op B" is just the LHS.
250       if (V == A) return LHS;
251       // Otherwise return "V op B" if it simplifies.
252       if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
253         ++NumReassoc;
254         return W;
255       }
256     }
257   }
258 
259   // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
260   if (Op1 && Op1->getOpcode() == Opcode) {
261     Value *A = LHS;
262     Value *B = Op1->getOperand(0);
263     Value *C = Op1->getOperand(1);
264 
265     // Does "C op A" simplify?
266     if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
267       // It does!  Return "B op V" if it simplifies or is already available.
268       // If V equals C then "B op V" is just the RHS.
269       if (V == C) return RHS;
270       // Otherwise return "B op V" if it simplifies.
271       if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
272         ++NumReassoc;
273         return W;
274       }
275     }
276   }
277 
278   return nullptr;
279 }
280 
281 /// In the case of a binary operation with a select instruction as an operand,
282 /// try to simplify the binop by seeing whether evaluating it on both branches
283 /// of the select results in the same value. Returns the common value if so,
284 /// otherwise returns null.
285 static Value *ThreadBinOpOverSelect(Instruction::BinaryOps Opcode, Value *LHS,
286                                     Value *RHS, const SimplifyQuery &Q,
287                                     unsigned MaxRecurse) {
288   // Recursion is always used, so bail out at once if we already hit the limit.
289   if (!MaxRecurse--)
290     return nullptr;
291 
292   SelectInst *SI;
293   if (isa<SelectInst>(LHS)) {
294     SI = cast<SelectInst>(LHS);
295   } else {
296     assert(isa<SelectInst>(RHS) && "No select instruction operand!");
297     SI = cast<SelectInst>(RHS);
298   }
299 
300   // Evaluate the BinOp on the true and false branches of the select.
301   Value *TV;
302   Value *FV;
303   if (SI == LHS) {
304     TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
305     FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
306   } else {
307     TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
308     FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
309   }
310 
311   // If they simplified to the same value, then return the common value.
312   // If they both failed to simplify then return null.
313   if (TV == FV)
314     return TV;
315 
316   // If one branch simplified to undef, return the other one.
317   if (TV && isa<UndefValue>(TV))
318     return FV;
319   if (FV && isa<UndefValue>(FV))
320     return TV;
321 
322   // If applying the operation did not change the true and false select values,
323   // then the result of the binop is the select itself.
324   if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
325     return SI;
326 
327   // If one branch simplified and the other did not, and the simplified
328   // value is equal to the unsimplified one, return the simplified value.
329   // For example, select (cond, X, X & Z) & Z -> X & Z.
330   if ((FV && !TV) || (TV && !FV)) {
331     // Check that the simplified value has the form "X op Y" where "op" is the
332     // same as the original operation.
333     Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
334     if (Simplified && Simplified->getOpcode() == Opcode) {
335       // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
336       // We already know that "op" is the same as for the simplified value.  See
337       // if the operands match too.  If so, return the simplified value.
338       Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
339       Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
340       Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
341       if (Simplified->getOperand(0) == UnsimplifiedLHS &&
342           Simplified->getOperand(1) == UnsimplifiedRHS)
343         return Simplified;
344       if (Simplified->isCommutative() &&
345           Simplified->getOperand(1) == UnsimplifiedLHS &&
346           Simplified->getOperand(0) == UnsimplifiedRHS)
347         return Simplified;
348     }
349   }
350 
351   return nullptr;
352 }
353 
354 /// In the case of a comparison with a select instruction, try to simplify the
355 /// comparison by seeing whether both branches of the select result in the same
356 /// value. Returns the common value if so, otherwise returns null.
357 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
358                                   Value *RHS, const SimplifyQuery &Q,
359                                   unsigned MaxRecurse) {
360   // Recursion is always used, so bail out at once if we already hit the limit.
361   if (!MaxRecurse--)
362     return nullptr;
363 
364   // Make sure the select is on the LHS.
365   if (!isa<SelectInst>(LHS)) {
366     std::swap(LHS, RHS);
367     Pred = CmpInst::getSwappedPredicate(Pred);
368   }
369   assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
370   SelectInst *SI = cast<SelectInst>(LHS);
371   Value *Cond = SI->getCondition();
372   Value *TV = SI->getTrueValue();
373   Value *FV = SI->getFalseValue();
374 
375   // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
376   // Does "cmp TV, RHS" simplify?
377   Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
378   if (TCmp == Cond) {
379     // It not only simplified, it simplified to the select condition.  Replace
380     // it with 'true'.
381     TCmp = getTrue(Cond->getType());
382   } else if (!TCmp) {
383     // It didn't simplify.  However if "cmp TV, RHS" is equal to the select
384     // condition then we can replace it with 'true'.  Otherwise give up.
385     if (!isSameCompare(Cond, Pred, TV, RHS))
386       return nullptr;
387     TCmp = getTrue(Cond->getType());
388   }
389 
390   // Does "cmp FV, RHS" simplify?
391   Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
392   if (FCmp == Cond) {
393     // It not only simplified, it simplified to the select condition.  Replace
394     // it with 'false'.
395     FCmp = getFalse(Cond->getType());
396   } else if (!FCmp) {
397     // It didn't simplify.  However if "cmp FV, RHS" is equal to the select
398     // condition then we can replace it with 'false'.  Otherwise give up.
399     if (!isSameCompare(Cond, Pred, FV, RHS))
400       return nullptr;
401     FCmp = getFalse(Cond->getType());
402   }
403 
404   // If both sides simplified to the same value, then use it as the result of
405   // the original comparison.
406   if (TCmp == FCmp)
407     return TCmp;
408 
409   // The remaining cases only make sense if the select condition has the same
410   // type as the result of the comparison, so bail out if this is not so.
411   if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
412     return nullptr;
413   // If the false value simplified to false, then the result of the compare
414   // is equal to "Cond && TCmp".  This also catches the case when the false
415   // value simplified to false and the true value to true, returning "Cond".
416   if (match(FCmp, m_Zero()))
417     if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
418       return V;
419   // If the true value simplified to true, then the result of the compare
420   // is equal to "Cond || FCmp".
421   if (match(TCmp, m_One()))
422     if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
423       return V;
424   // Finally, if the false value simplified to true and the true value to
425   // false, then the result of the compare is equal to "!Cond".
426   if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
427     if (Value *V =
428         SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
429                         Q, MaxRecurse))
430       return V;
431 
432   return nullptr;
433 }
434 
435 /// In the case of a binary operation with an operand that is a PHI instruction,
436 /// try to simplify the binop by seeing whether evaluating it on the incoming
437 /// phi values yields the same result for every value. If so returns the common
438 /// value, otherwise returns null.
439 static Value *ThreadBinOpOverPHI(Instruction::BinaryOps Opcode, Value *LHS,
440                                  Value *RHS, const SimplifyQuery &Q,
441                                  unsigned MaxRecurse) {
442   // Recursion is always used, so bail out at once if we already hit the limit.
443   if (!MaxRecurse--)
444     return nullptr;
445 
446   PHINode *PI;
447   if (isa<PHINode>(LHS)) {
448     PI = cast<PHINode>(LHS);
449     // Bail out if RHS and the phi may be mutually interdependent due to a loop.
450     if (!ValueDominatesPHI(RHS, PI, Q.DT))
451       return nullptr;
452   } else {
453     assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
454     PI = cast<PHINode>(RHS);
455     // Bail out if LHS and the phi may be mutually interdependent due to a loop.
456     if (!ValueDominatesPHI(LHS, PI, Q.DT))
457       return nullptr;
458   }
459 
460   // Evaluate the BinOp on the incoming phi values.
461   Value *CommonValue = nullptr;
462   for (Value *Incoming : PI->incoming_values()) {
463     // If the incoming value is the phi node itself, it can safely be skipped.
464     if (Incoming == PI) continue;
465     Value *V = PI == LHS ?
466       SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
467       SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
468     // If the operation failed to simplify, or simplified to a different value
469     // to previously, then give up.
470     if (!V || (CommonValue && V != CommonValue))
471       return nullptr;
472     CommonValue = V;
473   }
474 
475   return CommonValue;
476 }
477 
478 /// In the case of a comparison with a PHI instruction, try to simplify the
479 /// comparison by seeing whether comparing with all of the incoming phi values
480 /// yields the same result every time. If so returns the common result,
481 /// otherwise returns null.
482 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
483                                const SimplifyQuery &Q, unsigned MaxRecurse) {
484   // Recursion is always used, so bail out at once if we already hit the limit.
485   if (!MaxRecurse--)
486     return nullptr;
487 
488   // Make sure the phi is on the LHS.
489   if (!isa<PHINode>(LHS)) {
490     std::swap(LHS, RHS);
491     Pred = CmpInst::getSwappedPredicate(Pred);
492   }
493   assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
494   PHINode *PI = cast<PHINode>(LHS);
495 
496   // Bail out if RHS and the phi may be mutually interdependent due to a loop.
497   if (!ValueDominatesPHI(RHS, PI, Q.DT))
498     return nullptr;
499 
500   // Evaluate the BinOp on the incoming phi values.
501   Value *CommonValue = nullptr;
502   for (Value *Incoming : PI->incoming_values()) {
503     // If the incoming value is the phi node itself, it can safely be skipped.
504     if (Incoming == PI) continue;
505     Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
506     // If the operation failed to simplify, or simplified to a different value
507     // to previously, then give up.
508     if (!V || (CommonValue && V != CommonValue))
509       return nullptr;
510     CommonValue = V;
511   }
512 
513   return CommonValue;
514 }
515 
516 static Constant *foldOrCommuteConstant(Instruction::BinaryOps Opcode,
517                                        Value *&Op0, Value *&Op1,
518                                        const SimplifyQuery &Q) {
519   if (auto *CLHS = dyn_cast<Constant>(Op0)) {
520     if (auto *CRHS = dyn_cast<Constant>(Op1))
521       return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL);
522 
523     // Canonicalize the constant to the RHS if this is a commutative operation.
524     if (Instruction::isCommutative(Opcode))
525       std::swap(Op0, Op1);
526   }
527   return nullptr;
528 }
529 
530 /// Given operands for an Add, see if we can fold the result.
531 /// If not, this returns null.
532 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
533                               const SimplifyQuery &Q, unsigned MaxRecurse) {
534   if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q))
535     return C;
536 
537   // X + undef -> undef
538   if (match(Op1, m_Undef()))
539     return Op1;
540 
541   // X + 0 -> X
542   if (match(Op1, m_Zero()))
543     return Op0;
544 
545   // X + (Y - X) -> Y
546   // (Y - X) + X -> Y
547   // Eg: X + -X -> 0
548   Value *Y = nullptr;
549   if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
550       match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
551     return Y;
552 
553   // X + ~X -> -1   since   ~X = -X-1
554   Type *Ty = Op0->getType();
555   if (match(Op0, m_Not(m_Specific(Op1))) ||
556       match(Op1, m_Not(m_Specific(Op0))))
557     return Constant::getAllOnesValue(Ty);
558 
559   // add nsw/nuw (xor Y, signmask), signmask --> Y
560   // The no-wrapping add guarantees that the top bit will be set by the add.
561   // Therefore, the xor must be clearing the already set sign bit of Y.
562   if ((isNSW || isNUW) && match(Op1, m_SignMask()) &&
563       match(Op0, m_Xor(m_Value(Y), m_SignMask())))
564     return Y;
565 
566   /// i1 add -> xor.
567   if (MaxRecurse && Op0->getType()->getScalarType()->isIntegerTy(1))
568     if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
569       return V;
570 
571   // Try some generic simplifications for associative operations.
572   if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
573                                           MaxRecurse))
574     return V;
575 
576   // Threading Add over selects and phi nodes is pointless, so don't bother.
577   // Threading over the select in "A + select(cond, B, C)" means evaluating
578   // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
579   // only if B and C are equal.  If B and C are equal then (since we assume
580   // that operands have already been simplified) "select(cond, B, C)" should
581   // have been simplified to the common value of B and C already.  Analysing
582   // "A+B" and "A+C" thus gains nothing, but costs compile time.  Similarly
583   // for threading over phi nodes.
584 
585   return nullptr;
586 }
587 
588 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
589                              const SimplifyQuery &Query) {
590   return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query, RecursionLimit);
591 }
592 
593 /// \brief Compute the base pointer and cumulative constant offsets for V.
594 ///
595 /// This strips all constant offsets off of V, leaving it the base pointer, and
596 /// accumulates the total constant offset applied in the returned constant. It
597 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
598 /// no constant offsets applied.
599 ///
600 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
601 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
602 /// folding.
603 static Constant *stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V,
604                                                 bool AllowNonInbounds = false) {
605   assert(V->getType()->getScalarType()->isPointerTy());
606 
607   Type *IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType();
608   APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
609 
610   // Even though we don't look through PHI nodes, we could be called on an
611   // instruction in an unreachable block, which may be on a cycle.
612   SmallPtrSet<Value *, 4> Visited;
613   Visited.insert(V);
614   do {
615     if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
616       if ((!AllowNonInbounds && !GEP->isInBounds()) ||
617           !GEP->accumulateConstantOffset(DL, Offset))
618         break;
619       V = GEP->getPointerOperand();
620     } else if (Operator::getOpcode(V) == Instruction::BitCast) {
621       V = cast<Operator>(V)->getOperand(0);
622     } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
623       if (GA->isInterposable())
624         break;
625       V = GA->getAliasee();
626     } else {
627       if (auto CS = CallSite(V))
628         if (Value *RV = CS.getReturnedArgOperand()) {
629           V = RV;
630           continue;
631         }
632       break;
633     }
634     assert(V->getType()->getScalarType()->isPointerTy() &&
635            "Unexpected operand type!");
636   } while (Visited.insert(V).second);
637 
638   Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
639   if (V->getType()->isVectorTy())
640     return ConstantVector::getSplat(V->getType()->getVectorNumElements(),
641                                     OffsetIntPtr);
642   return OffsetIntPtr;
643 }
644 
645 /// \brief Compute the constant difference between two pointer values.
646 /// If the difference is not a constant, returns zero.
647 static Constant *computePointerDifference(const DataLayout &DL, Value *LHS,
648                                           Value *RHS) {
649   Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
650   Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
651 
652   // If LHS and RHS are not related via constant offsets to the same base
653   // value, there is nothing we can do here.
654   if (LHS != RHS)
655     return nullptr;
656 
657   // Otherwise, the difference of LHS - RHS can be computed as:
658   //    LHS - RHS
659   //  = (LHSOffset + Base) - (RHSOffset + Base)
660   //  = LHSOffset - RHSOffset
661   return ConstantExpr::getSub(LHSOffset, RHSOffset);
662 }
663 
664 /// Given operands for a Sub, see if we can fold the result.
665 /// If not, this returns null.
666 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
667                               const SimplifyQuery &Q, unsigned MaxRecurse) {
668   if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q))
669     return C;
670 
671   // X - undef -> undef
672   // undef - X -> undef
673   if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
674     return UndefValue::get(Op0->getType());
675 
676   // X - 0 -> X
677   if (match(Op1, m_Zero()))
678     return Op0;
679 
680   // X - X -> 0
681   if (Op0 == Op1)
682     return Constant::getNullValue(Op0->getType());
683 
684   // Is this a negation?
685   if (match(Op0, m_Zero())) {
686     // 0 - X -> 0 if the sub is NUW.
687     if (isNUW)
688       return Op0;
689 
690     unsigned BitWidth = Op1->getType()->getScalarSizeInBits();
691     KnownBits Known(BitWidth);
692     computeKnownBits(Op1, Known, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
693     if (Known.Zero.isMaxSignedValue()) {
694       // Op1 is either 0 or the minimum signed value. If the sub is NSW, then
695       // Op1 must be 0 because negating the minimum signed value is undefined.
696       if (isNSW)
697         return Op0;
698 
699       // 0 - X -> X if X is 0 or the minimum signed value.
700       return Op1;
701     }
702   }
703 
704   // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
705   // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
706   Value *X = nullptr, *Y = nullptr, *Z = Op1;
707   if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
708     // See if "V === Y - Z" simplifies.
709     if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
710       // It does!  Now see if "X + V" simplifies.
711       if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
712         // It does, we successfully reassociated!
713         ++NumReassoc;
714         return W;
715       }
716     // See if "V === X - Z" simplifies.
717     if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
718       // It does!  Now see if "Y + V" simplifies.
719       if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
720         // It does, we successfully reassociated!
721         ++NumReassoc;
722         return W;
723       }
724   }
725 
726   // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
727   // For example, X - (X + 1) -> -1
728   X = Op0;
729   if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
730     // See if "V === X - Y" simplifies.
731     if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
732       // It does!  Now see if "V - Z" simplifies.
733       if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
734         // It does, we successfully reassociated!
735         ++NumReassoc;
736         return W;
737       }
738     // See if "V === X - Z" simplifies.
739     if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
740       // It does!  Now see if "V - Y" simplifies.
741       if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
742         // It does, we successfully reassociated!
743         ++NumReassoc;
744         return W;
745       }
746   }
747 
748   // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
749   // For example, X - (X - Y) -> Y.
750   Z = Op0;
751   if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
752     // See if "V === Z - X" simplifies.
753     if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
754       // It does!  Now see if "V + Y" simplifies.
755       if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
756         // It does, we successfully reassociated!
757         ++NumReassoc;
758         return W;
759       }
760 
761   // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
762   if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
763       match(Op1, m_Trunc(m_Value(Y))))
764     if (X->getType() == Y->getType())
765       // See if "V === X - Y" simplifies.
766       if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
767         // It does!  Now see if "trunc V" simplifies.
768         if (Value *W = SimplifyCastInst(Instruction::Trunc, V, Op0->getType(),
769                                         Q, MaxRecurse - 1))
770           // It does, return the simplified "trunc V".
771           return W;
772 
773   // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
774   if (match(Op0, m_PtrToInt(m_Value(X))) &&
775       match(Op1, m_PtrToInt(m_Value(Y))))
776     if (Constant *Result = computePointerDifference(Q.DL, X, Y))
777       return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
778 
779   // i1 sub -> xor.
780   if (MaxRecurse && Op0->getType()->getScalarType()->isIntegerTy(1))
781     if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
782       return V;
783 
784   // Threading Sub over selects and phi nodes is pointless, so don't bother.
785   // Threading over the select in "A - select(cond, B, C)" means evaluating
786   // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
787   // only if B and C are equal.  If B and C are equal then (since we assume
788   // that operands have already been simplified) "select(cond, B, C)" should
789   // have been simplified to the common value of B and C already.  Analysing
790   // "A-B" and "A-C" thus gains nothing, but costs compile time.  Similarly
791   // for threading over phi nodes.
792 
793   return nullptr;
794 }
795 
796 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
797                              const SimplifyQuery &Q) {
798   return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
799 }
800 
801 /// Given operands for an FAdd, see if we can fold the result.  If not, this
802 /// returns null.
803 static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
804                               const SimplifyQuery &Q, unsigned MaxRecurse) {
805   if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q))
806     return C;
807 
808   // fadd X, -0 ==> X
809   if (match(Op1, m_NegZero()))
810     return Op0;
811 
812   // fadd X, 0 ==> X, when we know X is not -0
813   if (match(Op1, m_Zero()) &&
814       (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
815     return Op0;
816 
817   // fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
818   //   where nnan and ninf have to occur at least once somewhere in this
819   //   expression
820   Value *SubOp = nullptr;
821   if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0))))
822     SubOp = Op1;
823   else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1))))
824     SubOp = Op0;
825   if (SubOp) {
826     Instruction *FSub = cast<Instruction>(SubOp);
827     if ((FMF.noNaNs() || FSub->hasNoNaNs()) &&
828         (FMF.noInfs() || FSub->hasNoInfs()))
829       return Constant::getNullValue(Op0->getType());
830   }
831 
832   return nullptr;
833 }
834 
835 /// Given operands for an FSub, see if we can fold the result.  If not, this
836 /// returns null.
837 static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
838                               const SimplifyQuery &Q, unsigned MaxRecurse) {
839   if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q))
840     return C;
841 
842   // fsub X, 0 ==> X
843   if (match(Op1, m_Zero()))
844     return Op0;
845 
846   // fsub X, -0 ==> X, when we know X is not -0
847   if (match(Op1, m_NegZero()) &&
848       (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
849     return Op0;
850 
851   // fsub -0.0, (fsub -0.0, X) ==> X
852   Value *X;
853   if (match(Op0, m_NegZero()) && match(Op1, m_FSub(m_NegZero(), m_Value(X))))
854     return X;
855 
856   // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.
857   if (FMF.noSignedZeros() && match(Op0, m_AnyZero()) &&
858       match(Op1, m_FSub(m_AnyZero(), m_Value(X))))
859     return X;
860 
861   // fsub nnan x, x ==> 0.0
862   if (FMF.noNaNs() && Op0 == Op1)
863     return Constant::getNullValue(Op0->getType());
864 
865   return nullptr;
866 }
867 
868 /// Given the operands for an FMul, see if we can fold the result
869 static Value *SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
870                                const SimplifyQuery &Q, unsigned MaxRecurse) {
871   if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q))
872     return C;
873 
874   // fmul X, 1.0 ==> X
875   if (match(Op1, m_FPOne()))
876     return Op0;
877 
878   // fmul nnan nsz X, 0 ==> 0
879   if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero()))
880     return Op1;
881 
882   return nullptr;
883 }
884 
885 /// Given operands for a Mul, see if we can fold the result.
886 /// If not, this returns null.
887 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
888                               unsigned MaxRecurse) {
889   if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q))
890     return C;
891 
892   // X * undef -> 0
893   if (match(Op1, m_Undef()))
894     return Constant::getNullValue(Op0->getType());
895 
896   // X * 0 -> 0
897   if (match(Op1, m_Zero()))
898     return Op1;
899 
900   // X * 1 -> X
901   if (match(Op1, m_One()))
902     return Op0;
903 
904   // (X / Y) * Y -> X if the division is exact.
905   Value *X = nullptr;
906   if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
907       match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))   // Y * (X / Y)
908     return X;
909 
910   // i1 mul -> and.
911   if (MaxRecurse && Op0->getType()->getScalarType()->isIntegerTy(1))
912     if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
913       return V;
914 
915   // Try some generic simplifications for associative operations.
916   if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
917                                           MaxRecurse))
918     return V;
919 
920   // Mul distributes over Add.  Try some generic simplifications based on this.
921   if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
922                              Q, MaxRecurse))
923     return V;
924 
925   // If the operation is with the result of a select instruction, check whether
926   // operating on either branch of the select always yields the same value.
927   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
928     if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
929                                          MaxRecurse))
930       return V;
931 
932   // If the operation is with the result of a phi instruction, check whether
933   // operating on all incoming values of the phi always yields the same value.
934   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
935     if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
936                                       MaxRecurse))
937       return V;
938 
939   return nullptr;
940 }
941 
942 Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
943                               const SimplifyQuery &Q) {
944   return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit);
945 }
946 
947 
948 Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
949                               const SimplifyQuery &Q) {
950   return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit);
951 }
952 
953 Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
954                               const SimplifyQuery &Q) {
955   return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit);
956 }
957 
958 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
959   return ::SimplifyMulInst(Op0, Op1, Q, RecursionLimit);
960 }
961 
962 /// Check for common or similar folds of integer division or integer remainder.
963 static Value *simplifyDivRem(Value *Op0, Value *Op1, bool IsDiv) {
964   Type *Ty = Op0->getType();
965 
966   // X / undef -> undef
967   // X % undef -> undef
968   if (match(Op1, m_Undef()))
969     return Op1;
970 
971   // X / 0 -> undef
972   // X % 0 -> undef
973   // We don't need to preserve faults!
974   if (match(Op1, m_Zero()))
975     return UndefValue::get(Ty);
976 
977   // If any element of a constant divisor vector is zero, the whole op is undef.
978   auto *Op1C = dyn_cast<Constant>(Op1);
979   if (Op1C && Ty->isVectorTy()) {
980     unsigned NumElts = Ty->getVectorNumElements();
981     for (unsigned i = 0; i != NumElts; ++i) {
982       Constant *Elt = Op1C->getAggregateElement(i);
983       if (Elt && Elt->isNullValue())
984         return UndefValue::get(Ty);
985     }
986   }
987 
988   // undef / X -> 0
989   // undef % X -> 0
990   if (match(Op0, m_Undef()))
991     return Constant::getNullValue(Ty);
992 
993   // 0 / X -> 0
994   // 0 % X -> 0
995   if (match(Op0, m_Zero()))
996     return Op0;
997 
998   // X / X -> 1
999   // X % X -> 0
1000   if (Op0 == Op1)
1001     return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty);
1002 
1003   // X / 1 -> X
1004   // X % 1 -> 0
1005   // If this is a boolean op (single-bit element type), we can't have
1006   // division-by-zero or remainder-by-zero, so assume the divisor is 1.
1007   if (match(Op1, m_One()) || Ty->getScalarType()->isIntegerTy(1))
1008     return IsDiv ? Op0 : Constant::getNullValue(Ty);
1009 
1010   return nullptr;
1011 }
1012 
1013 /// Given operands for an SDiv or UDiv, see if we can fold the result.
1014 /// If not, this returns null.
1015 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1016                           const SimplifyQuery &Q, unsigned MaxRecurse) {
1017   if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1018     return C;
1019 
1020   if (Value *V = simplifyDivRem(Op0, Op1, true))
1021     return V;
1022 
1023   bool isSigned = Opcode == Instruction::SDiv;
1024 
1025   // (X * Y) / Y -> X if the multiplication does not overflow.
1026   Value *X = nullptr, *Y = nullptr;
1027   if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
1028     if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
1029     OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
1030     // If the Mul knows it does not overflow, then we are good to go.
1031     if ((isSigned && Mul->hasNoSignedWrap()) ||
1032         (!isSigned && Mul->hasNoUnsignedWrap()))
1033       return X;
1034     // If X has the form X = A / Y then X * Y cannot overflow.
1035     if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
1036       if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1037         return X;
1038   }
1039 
1040   // (X rem Y) / Y -> 0
1041   if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1042       (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1043     return Constant::getNullValue(Op0->getType());
1044 
1045   // (X /u C1) /u C2 -> 0 if C1 * C2 overflow
1046   ConstantInt *C1, *C2;
1047   if (!isSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
1048       match(Op1, m_ConstantInt(C2))) {
1049     bool Overflow;
1050     (void)C1->getValue().umul_ov(C2->getValue(), Overflow);
1051     if (Overflow)
1052       return Constant::getNullValue(Op0->getType());
1053   }
1054 
1055   // If the operation is with the result of a select instruction, check whether
1056   // operating on either branch of the select always yields the same value.
1057   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1058     if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1059       return V;
1060 
1061   // If the operation is with the result of a phi instruction, check whether
1062   // operating on all incoming values of the phi always yields the same value.
1063   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1064     if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1065       return V;
1066 
1067   return nullptr;
1068 }
1069 
1070 /// Given operands for an SDiv, see if we can fold the result.
1071 /// If not, this returns null.
1072 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1073                                unsigned MaxRecurse) {
1074   if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
1075     return V;
1076 
1077   return nullptr;
1078 }
1079 
1080 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1081   return ::SimplifySDivInst(Op0, Op1, Q, RecursionLimit);
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   if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
1089     return V;
1090 
1091   // udiv %V, C -> 0 if %V < C
1092   if (MaxRecurse) {
1093     if (Constant *C = dyn_cast_or_null<Constant>(SimplifyICmpInst(
1094             ICmpInst::ICMP_ULT, Op0, Op1, Q, MaxRecurse - 1))) {
1095       if (C->isAllOnesValue()) {
1096         return Constant::getNullValue(Op0->getType());
1097       }
1098     }
1099   }
1100 
1101   return nullptr;
1102 }
1103 
1104 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1105   return ::SimplifyUDivInst(Op0, Op1, Q, RecursionLimit);
1106 }
1107 
1108 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
1109                                const SimplifyQuery &Q, unsigned) {
1110   if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q))
1111     return C;
1112 
1113   // undef / X -> undef    (the undef could be a snan).
1114   if (match(Op0, m_Undef()))
1115     return Op0;
1116 
1117   // X / undef -> undef
1118   if (match(Op1, m_Undef()))
1119     return Op1;
1120 
1121   // X / 1.0 -> X
1122   if (match(Op1, m_FPOne()))
1123     return Op0;
1124 
1125   // 0 / X -> 0
1126   // Requires that NaNs are off (X could be zero) and signed zeroes are
1127   // ignored (X could be positive or negative, so the output sign is unknown).
1128   if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
1129     return Op0;
1130 
1131   if (FMF.noNaNs()) {
1132     // X / X -> 1.0 is legal when NaNs are ignored.
1133     if (Op0 == Op1)
1134       return ConstantFP::get(Op0->getType(), 1.0);
1135 
1136     // -X /  X -> -1.0 and
1137     //  X / -X -> -1.0 are legal when NaNs are ignored.
1138     // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored.
1139     if ((BinaryOperator::isFNeg(Op0, /*IgnoreZeroSign=*/true) &&
1140          BinaryOperator::getFNegArgument(Op0) == Op1) ||
1141         (BinaryOperator::isFNeg(Op1, /*IgnoreZeroSign=*/true) &&
1142          BinaryOperator::getFNegArgument(Op1) == Op0))
1143       return ConstantFP::get(Op0->getType(), -1.0);
1144   }
1145 
1146   return nullptr;
1147 }
1148 
1149 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
1150                               const SimplifyQuery &Q) {
1151   return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit);
1152 }
1153 
1154 /// Given operands for an SRem or URem, see if we can fold the result.
1155 /// If not, this returns null.
1156 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1157                           const SimplifyQuery &Q, unsigned MaxRecurse) {
1158   if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1159     return C;
1160 
1161   if (Value *V = simplifyDivRem(Op0, Op1, false))
1162     return V;
1163 
1164   // (X % Y) % Y -> X % Y
1165   if ((Opcode == Instruction::SRem &&
1166        match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1167       (Opcode == Instruction::URem &&
1168        match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1169     return Op0;
1170 
1171   // If the operation is with the result of a select instruction, check whether
1172   // operating on either branch of the select always yields the same value.
1173   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1174     if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1175       return V;
1176 
1177   // If the operation is with the result of a phi instruction, check whether
1178   // operating on all incoming values of the phi always yields the same value.
1179   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1180     if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1181       return V;
1182 
1183   return nullptr;
1184 }
1185 
1186 /// Given operands for an SRem, see if we can fold the result.
1187 /// If not, this returns null.
1188 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1189                                unsigned MaxRecurse) {
1190   if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
1191     return V;
1192 
1193   return nullptr;
1194 }
1195 
1196 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1197   return ::SimplifySRemInst(Op0, Op1, Q, RecursionLimit);
1198 }
1199 
1200 /// Given operands for a URem, see if we can fold the result.
1201 /// If not, this returns null.
1202 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1203                                unsigned MaxRecurse) {
1204   if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
1205     return V;
1206 
1207   // urem %V, C -> %V if %V < C
1208   if (MaxRecurse) {
1209     if (Constant *C = dyn_cast_or_null<Constant>(SimplifyICmpInst(
1210             ICmpInst::ICMP_ULT, Op0, Op1, Q, MaxRecurse - 1))) {
1211       if (C->isAllOnesValue()) {
1212         return Op0;
1213       }
1214     }
1215   }
1216 
1217   return nullptr;
1218 }
1219 
1220 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1221   return ::SimplifyURemInst(Op0, Op1, Q, RecursionLimit);
1222 }
1223 
1224 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
1225                                const SimplifyQuery &Q, unsigned) {
1226   if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q))
1227     return C;
1228 
1229   // undef % X -> undef    (the undef could be a snan).
1230   if (match(Op0, m_Undef()))
1231     return Op0;
1232 
1233   // X % undef -> undef
1234   if (match(Op1, m_Undef()))
1235     return Op1;
1236 
1237   // 0 % X -> 0
1238   // Requires that NaNs are off (X could be zero) and signed zeroes are
1239   // ignored (X could be positive or negative, so the output sign is unknown).
1240   if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
1241     return Op0;
1242 
1243   return nullptr;
1244 }
1245 
1246 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
1247                               const SimplifyQuery &Q) {
1248   return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit);
1249 }
1250 
1251 /// Returns true if a shift by \c Amount always yields undef.
1252 static bool isUndefShift(Value *Amount) {
1253   Constant *C = dyn_cast<Constant>(Amount);
1254   if (!C)
1255     return false;
1256 
1257   // X shift by undef -> undef because it may shift by the bitwidth.
1258   if (isa<UndefValue>(C))
1259     return true;
1260 
1261   // Shifting by the bitwidth or more is undefined.
1262   if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
1263     if (CI->getValue().getLimitedValue() >=
1264         CI->getType()->getScalarSizeInBits())
1265       return true;
1266 
1267   // If all lanes of a vector shift are undefined the whole shift is.
1268   if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
1269     for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I)
1270       if (!isUndefShift(C->getAggregateElement(I)))
1271         return false;
1272     return true;
1273   }
1274 
1275   return false;
1276 }
1277 
1278 /// Given operands for an Shl, LShr or AShr, see if we can fold the result.
1279 /// If not, this returns null.
1280 static Value *SimplifyShift(Instruction::BinaryOps Opcode, Value *Op0,
1281                             Value *Op1, const SimplifyQuery &Q, unsigned MaxRecurse) {
1282   if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1283     return C;
1284 
1285   // 0 shift by X -> 0
1286   if (match(Op0, m_Zero()))
1287     return Op0;
1288 
1289   // X shift by 0 -> X
1290   if (match(Op1, m_Zero()))
1291     return Op0;
1292 
1293   // Fold undefined shifts.
1294   if (isUndefShift(Op1))
1295     return UndefValue::get(Op0->getType());
1296 
1297   // If the operation is with the result of a select instruction, check whether
1298   // operating on either branch of the select always yields the same value.
1299   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1300     if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1301       return V;
1302 
1303   // If the operation is with the result of a phi instruction, check whether
1304   // operating on all incoming values of the phi always yields the same value.
1305   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1306     if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1307       return V;
1308 
1309   // If any bits in the shift amount make that value greater than or equal to
1310   // the number of bits in the type, the shift is undefined.
1311   unsigned BitWidth = Op1->getType()->getScalarSizeInBits();
1312   KnownBits Known(BitWidth);
1313   computeKnownBits(Op1, Known, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1314   if (Known.One.getLimitedValue() >= BitWidth)
1315     return UndefValue::get(Op0->getType());
1316 
1317   // If all valid bits in the shift amount are known zero, the first operand is
1318   // unchanged.
1319   unsigned NumValidShiftBits = Log2_32_Ceil(BitWidth);
1320   if (Known.Zero.countTrailingOnes() >= NumValidShiftBits)
1321     return Op0;
1322 
1323   return nullptr;
1324 }
1325 
1326 /// \brief Given operands for an Shl, LShr or AShr, see if we can
1327 /// fold the result.  If not, this returns null.
1328 static Value *SimplifyRightShift(Instruction::BinaryOps Opcode, Value *Op0,
1329                                  Value *Op1, bool isExact, const SimplifyQuery &Q,
1330                                  unsigned MaxRecurse) {
1331   if (Value *V = SimplifyShift(Opcode, Op0, Op1, Q, MaxRecurse))
1332     return V;
1333 
1334   // X >> X -> 0
1335   if (Op0 == Op1)
1336     return Constant::getNullValue(Op0->getType());
1337 
1338   // undef >> X -> 0
1339   // undef >> X -> undef (if it's exact)
1340   if (match(Op0, m_Undef()))
1341     return isExact ? Op0 : Constant::getNullValue(Op0->getType());
1342 
1343   // The low bit cannot be shifted out of an exact shift if it is set.
1344   if (isExact) {
1345     unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
1346     KnownBits Op0Known(BitWidth);
1347     computeKnownBits(Op0, Op0Known, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
1348     if (Op0Known.One[0])
1349       return Op0;
1350   }
1351 
1352   return nullptr;
1353 }
1354 
1355 /// Given operands for an Shl, see if we can fold the result.
1356 /// If not, this returns null.
1357 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1358                               const SimplifyQuery &Q, unsigned MaxRecurse) {
1359   if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1360     return V;
1361 
1362   // undef << X -> 0
1363   // undef << X -> undef if (if it's NSW/NUW)
1364   if (match(Op0, m_Undef()))
1365     return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType());
1366 
1367   // (X >> A) << A -> X
1368   Value *X;
1369   if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1370     return X;
1371   return nullptr;
1372 }
1373 
1374 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1375                              const SimplifyQuery &Q) {
1376   return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
1377 }
1378 
1379 /// Given operands for an LShr, see if we can fold the result.
1380 /// If not, this returns null.
1381 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1382                                const SimplifyQuery &Q, unsigned MaxRecurse) {
1383   if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q,
1384                                     MaxRecurse))
1385       return V;
1386 
1387   // (X << A) >> A -> X
1388   Value *X;
1389   if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
1390     return X;
1391 
1392   return nullptr;
1393 }
1394 
1395 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1396                               const SimplifyQuery &Q) {
1397   return ::SimplifyLShrInst(Op0, Op1, isExact, Q, RecursionLimit);
1398 }
1399 
1400 /// Given operands for an AShr, see if we can fold the result.
1401 /// If not, this returns null.
1402 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1403                                const SimplifyQuery &Q, unsigned MaxRecurse) {
1404   if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
1405                                     MaxRecurse))
1406     return V;
1407 
1408   // all ones >>a X -> all ones
1409   if (match(Op0, m_AllOnes()))
1410     return Op0;
1411 
1412   // (X << A) >> A -> X
1413   Value *X;
1414   if (match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
1415     return X;
1416 
1417   // Arithmetic shifting an all-sign-bit value is a no-op.
1418   unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
1419   if (NumSignBits == Op0->getType()->getScalarSizeInBits())
1420     return Op0;
1421 
1422   return nullptr;
1423 }
1424 
1425 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1426                               const SimplifyQuery &Q) {
1427   return ::SimplifyAShrInst(Op0, Op1, isExact, Q, RecursionLimit);
1428 }
1429 
1430 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp,
1431                                          ICmpInst *UnsignedICmp, bool IsAnd) {
1432   Value *X, *Y;
1433 
1434   ICmpInst::Predicate EqPred;
1435   if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) ||
1436       !ICmpInst::isEquality(EqPred))
1437     return nullptr;
1438 
1439   ICmpInst::Predicate UnsignedPred;
1440   if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
1441       ICmpInst::isUnsigned(UnsignedPred))
1442     ;
1443   else if (match(UnsignedICmp,
1444                  m_ICmp(UnsignedPred, m_Value(Y), m_Specific(X))) &&
1445            ICmpInst::isUnsigned(UnsignedPred))
1446     UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
1447   else
1448     return nullptr;
1449 
1450   // X < Y && Y != 0  -->  X < Y
1451   // X < Y || Y != 0  -->  Y != 0
1452   if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE)
1453     return IsAnd ? UnsignedICmp : ZeroICmp;
1454 
1455   // X >= Y || Y != 0  -->  true
1456   // X >= Y || Y == 0  -->  X >= Y
1457   if (UnsignedPred == ICmpInst::ICMP_UGE && !IsAnd) {
1458     if (EqPred == ICmpInst::ICMP_NE)
1459       return getTrue(UnsignedICmp->getType());
1460     return UnsignedICmp;
1461   }
1462 
1463   // X < Y && Y == 0  -->  false
1464   if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
1465       IsAnd)
1466     return getFalse(UnsignedICmp->getType());
1467 
1468   return nullptr;
1469 }
1470 
1471 /// Commuted variants are assumed to be handled by calling this function again
1472 /// with the parameters swapped.
1473 static Value *simplifyAndOfICmpsWithSameOperands(ICmpInst *Op0, ICmpInst *Op1) {
1474   ICmpInst::Predicate Pred0, Pred1;
1475   Value *A ,*B;
1476   if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
1477       !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
1478     return nullptr;
1479 
1480   // We have (icmp Pred0, A, B) & (icmp Pred1, A, B).
1481   // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
1482   // can eliminate Op1 from this 'and'.
1483   if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
1484     return Op0;
1485 
1486   // Check for any combination of predicates that are guaranteed to be disjoint.
1487   if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
1488       (Pred0 == ICmpInst::ICMP_EQ && ICmpInst::isFalseWhenEqual(Pred1)) ||
1489       (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT) ||
1490       (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT))
1491     return getFalse(Op0->getType());
1492 
1493   return nullptr;
1494 }
1495 
1496 /// Commuted variants are assumed to be handled by calling this function again
1497 /// with the parameters swapped.
1498 static Value *simplifyOrOfICmpsWithSameOperands(ICmpInst *Op0, ICmpInst *Op1) {
1499   ICmpInst::Predicate Pred0, Pred1;
1500   Value *A ,*B;
1501   if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
1502       !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
1503     return nullptr;
1504 
1505   // We have (icmp Pred0, A, B) | (icmp Pred1, A, B).
1506   // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
1507   // can eliminate Op0 from this 'or'.
1508   if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
1509     return Op1;
1510 
1511   // Check for any combination of predicates that cover the entire range of
1512   // possibilities.
1513   if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
1514       (Pred0 == ICmpInst::ICMP_NE && ICmpInst::isTrueWhenEqual(Pred1)) ||
1515       (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGE) ||
1516       (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGE))
1517     return getTrue(Op0->getType());
1518 
1519   return nullptr;
1520 }
1521 
1522 /// Test if a pair of compares with a shared operand and 2 constants has an
1523 /// empty set intersection, full set union, or if one compare is a superset of
1524 /// the other.
1525 static Value *simplifyAndOrOfICmpsWithConstants(ICmpInst *Cmp0, ICmpInst *Cmp1,
1526                                                 bool IsAnd) {
1527   // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)).
1528   if (Cmp0->getOperand(0) != Cmp1->getOperand(0))
1529     return nullptr;
1530 
1531   const APInt *C0, *C1;
1532   if (!match(Cmp0->getOperand(1), m_APInt(C0)) ||
1533       !match(Cmp1->getOperand(1), m_APInt(C1)))
1534     return nullptr;
1535 
1536   auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0);
1537   auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1);
1538 
1539   // For and-of-compares, check if the intersection is empty:
1540   // (icmp X, C0) && (icmp X, C1) --> empty set --> false
1541   if (IsAnd && Range0.intersectWith(Range1).isEmptySet())
1542     return getFalse(Cmp0->getType());
1543 
1544   // For or-of-compares, check if the union is full:
1545   // (icmp X, C0) || (icmp X, C1) --> full set --> true
1546   if (!IsAnd && Range0.unionWith(Range1).isFullSet())
1547     return getTrue(Cmp0->getType());
1548 
1549   // Is one range a superset of the other?
1550   // If this is and-of-compares, take the smaller set:
1551   // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42
1552   // If this is or-of-compares, take the larger set:
1553   // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4
1554   if (Range0.contains(Range1))
1555     return IsAnd ? Cmp1 : Cmp0;
1556   if (Range1.contains(Range0))
1557     return IsAnd ? Cmp0 : Cmp1;
1558 
1559   return nullptr;
1560 }
1561 
1562 /// Commuted variants are assumed to be handled by calling this function again
1563 /// with the parameters swapped.
1564 static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
1565   if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true))
1566     return X;
1567 
1568   if (Value *X = simplifyAndOfICmpsWithSameOperands(Op0, Op1))
1569     return X;
1570 
1571   if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true))
1572     return X;
1573 
1574   // (icmp (add V, C0), C1) & (icmp V, C0)
1575   Type *ITy = Op0->getType();
1576   ICmpInst::Predicate Pred0, Pred1;
1577   const APInt *C0, *C1;
1578   Value *V;
1579   if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1580     return nullptr;
1581 
1582   if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1583     return nullptr;
1584 
1585   auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1586   if (AddInst->getOperand(1) != Op1->getOperand(1))
1587     return nullptr;
1588 
1589   bool isNSW = AddInst->hasNoSignedWrap();
1590   bool isNUW = AddInst->hasNoUnsignedWrap();
1591 
1592   const APInt Delta = *C1 - *C0;
1593   if (C0->isStrictlyPositive()) {
1594     if (Delta == 2) {
1595       if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
1596         return getFalse(ITy);
1597       if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1598         return getFalse(ITy);
1599     }
1600     if (Delta == 1) {
1601       if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
1602         return getFalse(ITy);
1603       if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
1604         return getFalse(ITy);
1605     }
1606   }
1607   if (C0->getBoolValue() && isNUW) {
1608     if (Delta == 2)
1609       if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
1610         return getFalse(ITy);
1611     if (Delta == 1)
1612       if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
1613         return getFalse(ITy);
1614   }
1615 
1616   return nullptr;
1617 }
1618 
1619 /// Commuted variants are assumed to be handled by calling this function again
1620 /// with the parameters swapped.
1621 static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
1622   if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false))
1623     return X;
1624 
1625   if (Value *X = simplifyOrOfICmpsWithSameOperands(Op0, Op1))
1626     return X;
1627 
1628   if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false))
1629     return X;
1630 
1631   // (icmp (add V, C0), C1) | (icmp V, C0)
1632   ICmpInst::Predicate Pred0, Pred1;
1633   const APInt *C0, *C1;
1634   Value *V;
1635   if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1636     return nullptr;
1637 
1638   if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1639     return nullptr;
1640 
1641   auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1642   if (AddInst->getOperand(1) != Op1->getOperand(1))
1643     return nullptr;
1644 
1645   Type *ITy = Op0->getType();
1646   bool isNSW = AddInst->hasNoSignedWrap();
1647   bool isNUW = AddInst->hasNoUnsignedWrap();
1648 
1649   const APInt Delta = *C1 - *C0;
1650   if (C0->isStrictlyPositive()) {
1651     if (Delta == 2) {
1652       if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
1653         return getTrue(ITy);
1654       if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1655         return getTrue(ITy);
1656     }
1657     if (Delta == 1) {
1658       if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
1659         return getTrue(ITy);
1660       if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
1661         return getTrue(ITy);
1662     }
1663   }
1664   if (C0->getBoolValue() && isNUW) {
1665     if (Delta == 2)
1666       if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
1667         return getTrue(ITy);
1668     if (Delta == 1)
1669       if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
1670         return getTrue(ITy);
1671   }
1672 
1673   return nullptr;
1674 }
1675 
1676 static Value *simplifyPossiblyCastedAndOrOfICmps(ICmpInst *Cmp0, ICmpInst *Cmp1,
1677                                                  bool IsAnd, CastInst *Cast) {
1678   Value *V =
1679       IsAnd ? simplifyAndOfICmps(Cmp0, Cmp1) : simplifyOrOfICmps(Cmp0, Cmp1);
1680   if (!V)
1681     return nullptr;
1682   if (!Cast)
1683     return V;
1684 
1685   // If we looked through casts, we can only handle a constant simplification
1686   // because we are not allowed to create a cast instruction here.
1687   if (auto *C = dyn_cast<Constant>(V))
1688     return ConstantExpr::getCast(Cast->getOpcode(), C, Cast->getType());
1689 
1690   return nullptr;
1691 }
1692 
1693 static Value *simplifyAndOrOfICmps(Value *Op0, Value *Op1, bool IsAnd) {
1694   // Look through casts of the 'and' operands to find compares.
1695   auto *Cast0 = dyn_cast<CastInst>(Op0);
1696   auto *Cast1 = dyn_cast<CastInst>(Op1);
1697   if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() &&
1698       Cast0->getSrcTy() == Cast1->getSrcTy()) {
1699     Op0 = Cast0->getOperand(0);
1700     Op1 = Cast1->getOperand(0);
1701   }
1702 
1703   auto *Cmp0 = dyn_cast<ICmpInst>(Op0);
1704   auto *Cmp1 = dyn_cast<ICmpInst>(Op1);
1705   if (!Cmp0 || !Cmp1)
1706     return nullptr;
1707 
1708   if (Value *V = simplifyPossiblyCastedAndOrOfICmps(Cmp0, Cmp1, IsAnd, Cast0))
1709     return V;
1710   if (Value *V = simplifyPossiblyCastedAndOrOfICmps(Cmp1, Cmp0, IsAnd, Cast0))
1711     return V;
1712 
1713   return nullptr;
1714 }
1715 
1716 /// Given operands for an And, see if we can fold the result.
1717 /// If not, this returns null.
1718 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1719                               unsigned MaxRecurse) {
1720   if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q))
1721     return C;
1722 
1723   // X & undef -> 0
1724   if (match(Op1, m_Undef()))
1725     return Constant::getNullValue(Op0->getType());
1726 
1727   // X & X = X
1728   if (Op0 == Op1)
1729     return Op0;
1730 
1731   // X & 0 = 0
1732   if (match(Op1, m_Zero()))
1733     return Op1;
1734 
1735   // X & -1 = X
1736   if (match(Op1, m_AllOnes()))
1737     return Op0;
1738 
1739   // A & ~A  =  ~A & A  =  0
1740   if (match(Op0, m_Not(m_Specific(Op1))) ||
1741       match(Op1, m_Not(m_Specific(Op0))))
1742     return Constant::getNullValue(Op0->getType());
1743 
1744   // (A | ?) & A = A
1745   Value *A = nullptr, *B = nullptr;
1746   if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1747       (A == Op1 || B == Op1))
1748     return Op1;
1749 
1750   // A & (A | ?) = A
1751   if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1752       (A == Op0 || B == Op0))
1753     return Op0;
1754 
1755   // A & (-A) = A if A is a power of two or zero.
1756   if (match(Op0, m_Neg(m_Specific(Op1))) ||
1757       match(Op1, m_Neg(m_Specific(Op0)))) {
1758     if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1759                                Q.DT))
1760       return Op0;
1761     if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
1762                                Q.DT))
1763       return Op1;
1764   }
1765 
1766   if (Value *V = simplifyAndOrOfICmps(Op0, Op1, true))
1767     return V;
1768 
1769   // Try some generic simplifications for associative operations.
1770   if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1771                                           MaxRecurse))
1772     return V;
1773 
1774   // And distributes over Or.  Try some generic simplifications based on this.
1775   if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1776                              Q, MaxRecurse))
1777     return V;
1778 
1779   // And distributes over Xor.  Try some generic simplifications based on this.
1780   if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1781                              Q, MaxRecurse))
1782     return V;
1783 
1784   // If the operation is with the result of a select instruction, check whether
1785   // operating on either branch of the select always yields the same value.
1786   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1787     if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1788                                          MaxRecurse))
1789       return V;
1790 
1791   // If the operation is with the result of a phi instruction, check whether
1792   // operating on all incoming values of the phi always yields the same value.
1793   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1794     if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1795                                       MaxRecurse))
1796       return V;
1797 
1798   return nullptr;
1799 }
1800 
1801 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1802   return ::SimplifyAndInst(Op0, Op1, Q, RecursionLimit);
1803 }
1804 
1805 /// Given operands for an Or, see if we can fold the result.
1806 /// If not, this returns null.
1807 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1808                              unsigned MaxRecurse) {
1809   if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q))
1810     return C;
1811 
1812   // X | undef -> -1
1813   if (match(Op1, m_Undef()))
1814     return Constant::getAllOnesValue(Op0->getType());
1815 
1816   // X | X = X
1817   if (Op0 == Op1)
1818     return Op0;
1819 
1820   // X | 0 = X
1821   if (match(Op1, m_Zero()))
1822     return Op0;
1823 
1824   // X | -1 = -1
1825   if (match(Op1, m_AllOnes()))
1826     return Op1;
1827 
1828   // A | ~A  =  ~A | A  =  -1
1829   if (match(Op0, m_Not(m_Specific(Op1))) ||
1830       match(Op1, m_Not(m_Specific(Op0))))
1831     return Constant::getAllOnesValue(Op0->getType());
1832 
1833   // (A & ?) | A = A
1834   Value *A = nullptr, *B = nullptr;
1835   if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1836       (A == Op1 || B == Op1))
1837     return Op1;
1838 
1839   // A | (A & ?) = A
1840   if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1841       (A == Op0 || B == Op0))
1842     return Op0;
1843 
1844   // ~(A & ?) | A = -1
1845   if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1846       (A == Op1 || B == Op1))
1847     return Constant::getAllOnesValue(Op1->getType());
1848 
1849   // A | ~(A & ?) = -1
1850   if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1851       (A == Op0 || B == Op0))
1852     return Constant::getAllOnesValue(Op0->getType());
1853 
1854   // (A & ~B) | (A ^ B) -> (A ^ B)
1855   // (~B & A) | (A ^ B) -> (A ^ B)
1856   // (A & ~B) | (B ^ A) -> (B ^ A)
1857   // (~B & A) | (B ^ A) -> (B ^ A)
1858   if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
1859       (match(Op0, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
1860        match(Op0, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
1861     return Op1;
1862 
1863   // Commute the 'or' operands.
1864   // (A ^ B) | (A & ~B) -> (A ^ B)
1865   // (A ^ B) | (~B & A) -> (A ^ B)
1866   // (B ^ A) | (A & ~B) -> (B ^ A)
1867   // (B ^ A) | (~B & A) -> (B ^ A)
1868   if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
1869       (match(Op1, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
1870        match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
1871     return Op0;
1872 
1873   if (Value *V = simplifyAndOrOfICmps(Op0, Op1, false))
1874     return V;
1875 
1876   // Try some generic simplifications for associative operations.
1877   if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1878                                           MaxRecurse))
1879     return V;
1880 
1881   // Or distributes over And.  Try some generic simplifications based on this.
1882   if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1883                              MaxRecurse))
1884     return V;
1885 
1886   // If the operation is with the result of a select instruction, check whether
1887   // operating on either branch of the select always yields the same value.
1888   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1889     if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1890                                          MaxRecurse))
1891       return V;
1892 
1893   // (A & C)|(B & D)
1894   Value *C = nullptr, *D = nullptr;
1895   if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
1896       match(Op1, m_And(m_Value(B), m_Value(D)))) {
1897     ConstantInt *C1 = dyn_cast<ConstantInt>(C);
1898     ConstantInt *C2 = dyn_cast<ConstantInt>(D);
1899     if (C1 && C2 && (C1->getValue() == ~C2->getValue())) {
1900       // (A & C1)|(B & C2)
1901       // If we have: ((V + N) & C1) | (V & C2)
1902       // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1903       // replace with V+N.
1904       Value *V1, *V2;
1905       if ((C2->getValue() & (C2->getValue() + 1)) == 0 && // C2 == 0+1+
1906           match(A, m_Add(m_Value(V1), m_Value(V2)))) {
1907         // Add commutes, try both ways.
1908         if (V1 == B &&
1909             MaskedValueIsZero(V2, C2->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1910           return A;
1911         if (V2 == B &&
1912             MaskedValueIsZero(V1, C2->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1913           return A;
1914       }
1915       // Or commutes, try both ways.
1916       if ((C1->getValue() & (C1->getValue() + 1)) == 0 &&
1917           match(B, m_Add(m_Value(V1), m_Value(V2)))) {
1918         // Add commutes, try both ways.
1919         if (V1 == A &&
1920             MaskedValueIsZero(V2, C1->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1921           return B;
1922         if (V2 == A &&
1923             MaskedValueIsZero(V1, C1->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
1924           return B;
1925       }
1926     }
1927   }
1928 
1929   // If the operation is with the result of a phi instruction, check whether
1930   // operating on all incoming values of the phi always yields the same value.
1931   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1932     if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1933       return V;
1934 
1935   return nullptr;
1936 }
1937 
1938 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1939   return ::SimplifyOrInst(Op0, Op1, Q, RecursionLimit);
1940 }
1941 
1942 /// Given operands for a Xor, see if we can fold the result.
1943 /// If not, this returns null.
1944 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1945                               unsigned MaxRecurse) {
1946   if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q))
1947     return C;
1948 
1949   // A ^ undef -> undef
1950   if (match(Op1, m_Undef()))
1951     return Op1;
1952 
1953   // A ^ 0 = A
1954   if (match(Op1, m_Zero()))
1955     return Op0;
1956 
1957   // A ^ A = 0
1958   if (Op0 == Op1)
1959     return Constant::getNullValue(Op0->getType());
1960 
1961   // A ^ ~A  =  ~A ^ A  =  -1
1962   if (match(Op0, m_Not(m_Specific(Op1))) ||
1963       match(Op1, m_Not(m_Specific(Op0))))
1964     return Constant::getAllOnesValue(Op0->getType());
1965 
1966   // Try some generic simplifications for associative operations.
1967   if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1968                                           MaxRecurse))
1969     return V;
1970 
1971   // Threading Xor over selects and phi nodes is pointless, so don't bother.
1972   // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1973   // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1974   // only if B and C are equal.  If B and C are equal then (since we assume
1975   // that operands have already been simplified) "select(cond, B, C)" should
1976   // have been simplified to the common value of B and C already.  Analysing
1977   // "A^B" and "A^C" thus gains nothing, but costs compile time.  Similarly
1978   // for threading over phi nodes.
1979 
1980   return nullptr;
1981 }
1982 
1983 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1984   return ::SimplifyXorInst(Op0, Op1, Q, RecursionLimit);
1985 }
1986 
1987 
1988 static Type *GetCompareTy(Value *Op) {
1989   return CmpInst::makeCmpResultType(Op->getType());
1990 }
1991 
1992 /// Rummage around inside V looking for something equivalent to the comparison
1993 /// "LHS Pred RHS". Return such a value if found, otherwise return null.
1994 /// Helper function for analyzing max/min idioms.
1995 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1996                                          Value *LHS, Value *RHS) {
1997   SelectInst *SI = dyn_cast<SelectInst>(V);
1998   if (!SI)
1999     return nullptr;
2000   CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
2001   if (!Cmp)
2002     return nullptr;
2003   Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
2004   if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
2005     return Cmp;
2006   if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
2007       LHS == CmpRHS && RHS == CmpLHS)
2008     return Cmp;
2009   return nullptr;
2010 }
2011 
2012 // A significant optimization not implemented here is assuming that alloca
2013 // addresses are not equal to incoming argument values. They don't *alias*,
2014 // as we say, but that doesn't mean they aren't equal, so we take a
2015 // conservative approach.
2016 //
2017 // This is inspired in part by C++11 5.10p1:
2018 //   "Two pointers of the same type compare equal if and only if they are both
2019 //    null, both point to the same function, or both represent the same
2020 //    address."
2021 //
2022 // This is pretty permissive.
2023 //
2024 // It's also partly due to C11 6.5.9p6:
2025 //   "Two pointers compare equal if and only if both are null pointers, both are
2026 //    pointers to the same object (including a pointer to an object and a
2027 //    subobject at its beginning) or function, both are pointers to one past the
2028 //    last element of the same array object, or one is a pointer to one past the
2029 //    end of one array object and the other is a pointer to the start of a
2030 //    different array object that happens to immediately follow the first array
2031 //    object in the address space.)
2032 //
2033 // C11's version is more restrictive, however there's no reason why an argument
2034 // couldn't be a one-past-the-end value for a stack object in the caller and be
2035 // equal to the beginning of a stack object in the callee.
2036 //
2037 // If the C and C++ standards are ever made sufficiently restrictive in this
2038 // area, it may be possible to update LLVM's semantics accordingly and reinstate
2039 // this optimization.
2040 static Constant *
2041 computePointerICmp(const DataLayout &DL, const TargetLibraryInfo *TLI,
2042                    const DominatorTree *DT, CmpInst::Predicate Pred,
2043                    const Instruction *CxtI, Value *LHS, Value *RHS) {
2044   // First, skip past any trivial no-ops.
2045   LHS = LHS->stripPointerCasts();
2046   RHS = RHS->stripPointerCasts();
2047 
2048   // A non-null pointer is not equal to a null pointer.
2049   if (llvm::isKnownNonNull(LHS) && isa<ConstantPointerNull>(RHS) &&
2050       (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE))
2051     return ConstantInt::get(GetCompareTy(LHS),
2052                             !CmpInst::isTrueWhenEqual(Pred));
2053 
2054   // We can only fold certain predicates on pointer comparisons.
2055   switch (Pred) {
2056   default:
2057     return nullptr;
2058 
2059     // Equality comaprisons are easy to fold.
2060   case CmpInst::ICMP_EQ:
2061   case CmpInst::ICMP_NE:
2062     break;
2063 
2064     // We can only handle unsigned relational comparisons because 'inbounds' on
2065     // a GEP only protects against unsigned wrapping.
2066   case CmpInst::ICMP_UGT:
2067   case CmpInst::ICMP_UGE:
2068   case CmpInst::ICMP_ULT:
2069   case CmpInst::ICMP_ULE:
2070     // However, we have to switch them to their signed variants to handle
2071     // negative indices from the base pointer.
2072     Pred = ICmpInst::getSignedPredicate(Pred);
2073     break;
2074   }
2075 
2076   // Strip off any constant offsets so that we can reason about them.
2077   // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
2078   // here and compare base addresses like AliasAnalysis does, however there are
2079   // numerous hazards. AliasAnalysis and its utilities rely on special rules
2080   // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
2081   // doesn't need to guarantee pointer inequality when it says NoAlias.
2082   Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
2083   Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
2084 
2085   // If LHS and RHS are related via constant offsets to the same base
2086   // value, we can replace it with an icmp which just compares the offsets.
2087   if (LHS == RHS)
2088     return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
2089 
2090   // Various optimizations for (in)equality comparisons.
2091   if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
2092     // Different non-empty allocations that exist at the same time have
2093     // different addresses (if the program can tell). Global variables always
2094     // exist, so they always exist during the lifetime of each other and all
2095     // allocas. Two different allocas usually have different addresses...
2096     //
2097     // However, if there's an @llvm.stackrestore dynamically in between two
2098     // allocas, they may have the same address. It's tempting to reduce the
2099     // scope of the problem by only looking at *static* allocas here. That would
2100     // cover the majority of allocas while significantly reducing the likelihood
2101     // of having an @llvm.stackrestore pop up in the middle. However, it's not
2102     // actually impossible for an @llvm.stackrestore to pop up in the middle of
2103     // an entry block. Also, if we have a block that's not attached to a
2104     // function, we can't tell if it's "static" under the current definition.
2105     // Theoretically, this problem could be fixed by creating a new kind of
2106     // instruction kind specifically for static allocas. Such a new instruction
2107     // could be required to be at the top of the entry block, thus preventing it
2108     // from being subject to a @llvm.stackrestore. Instcombine could even
2109     // convert regular allocas into these special allocas. It'd be nifty.
2110     // However, until then, this problem remains open.
2111     //
2112     // So, we'll assume that two non-empty allocas have different addresses
2113     // for now.
2114     //
2115     // With all that, if the offsets are within the bounds of their allocations
2116     // (and not one-past-the-end! so we can't use inbounds!), and their
2117     // allocations aren't the same, the pointers are not equal.
2118     //
2119     // Note that it's not necessary to check for LHS being a global variable
2120     // address, due to canonicalization and constant folding.
2121     if (isa<AllocaInst>(LHS) &&
2122         (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
2123       ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
2124       ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
2125       uint64_t LHSSize, RHSSize;
2126       if (LHSOffsetCI && RHSOffsetCI &&
2127           getObjectSize(LHS, LHSSize, DL, TLI) &&
2128           getObjectSize(RHS, RHSSize, DL, TLI)) {
2129         const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
2130         const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
2131         if (!LHSOffsetValue.isNegative() &&
2132             !RHSOffsetValue.isNegative() &&
2133             LHSOffsetValue.ult(LHSSize) &&
2134             RHSOffsetValue.ult(RHSSize)) {
2135           return ConstantInt::get(GetCompareTy(LHS),
2136                                   !CmpInst::isTrueWhenEqual(Pred));
2137         }
2138       }
2139 
2140       // Repeat the above check but this time without depending on DataLayout
2141       // or being able to compute a precise size.
2142       if (!cast<PointerType>(LHS->getType())->isEmptyTy() &&
2143           !cast<PointerType>(RHS->getType())->isEmptyTy() &&
2144           LHSOffset->isNullValue() &&
2145           RHSOffset->isNullValue())
2146         return ConstantInt::get(GetCompareTy(LHS),
2147                                 !CmpInst::isTrueWhenEqual(Pred));
2148     }
2149 
2150     // Even if an non-inbounds GEP occurs along the path we can still optimize
2151     // equality comparisons concerning the result. We avoid walking the whole
2152     // chain again by starting where the last calls to
2153     // stripAndComputeConstantOffsets left off and accumulate the offsets.
2154     Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true);
2155     Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true);
2156     if (LHS == RHS)
2157       return ConstantExpr::getICmp(Pred,
2158                                    ConstantExpr::getAdd(LHSOffset, LHSNoBound),
2159                                    ConstantExpr::getAdd(RHSOffset, RHSNoBound));
2160 
2161     // If one side of the equality comparison must come from a noalias call
2162     // (meaning a system memory allocation function), and the other side must
2163     // come from a pointer that cannot overlap with dynamically-allocated
2164     // memory within the lifetime of the current function (allocas, byval
2165     // arguments, globals), then determine the comparison result here.
2166     SmallVector<Value *, 8> LHSUObjs, RHSUObjs;
2167     GetUnderlyingObjects(LHS, LHSUObjs, DL);
2168     GetUnderlyingObjects(RHS, RHSUObjs, DL);
2169 
2170     // Is the set of underlying objects all noalias calls?
2171     auto IsNAC = [](ArrayRef<Value *> Objects) {
2172       return all_of(Objects, isNoAliasCall);
2173     };
2174 
2175     // Is the set of underlying objects all things which must be disjoint from
2176     // noalias calls. For allocas, we consider only static ones (dynamic
2177     // allocas might be transformed into calls to malloc not simultaneously
2178     // live with the compared-to allocation). For globals, we exclude symbols
2179     // that might be resolve lazily to symbols in another dynamically-loaded
2180     // library (and, thus, could be malloc'ed by the implementation).
2181     auto IsAllocDisjoint = [](ArrayRef<Value *> Objects) {
2182       return all_of(Objects, [](Value *V) {
2183         if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
2184           return AI->getParent() && AI->getFunction() && AI->isStaticAlloca();
2185         if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
2186           return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() ||
2187                   GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) &&
2188                  !GV->isThreadLocal();
2189         if (const Argument *A = dyn_cast<Argument>(V))
2190           return A->hasByValAttr();
2191         return false;
2192       });
2193     };
2194 
2195     if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
2196         (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
2197         return ConstantInt::get(GetCompareTy(LHS),
2198                                 !CmpInst::isTrueWhenEqual(Pred));
2199 
2200     // Fold comparisons for non-escaping pointer even if the allocation call
2201     // cannot be elided. We cannot fold malloc comparison to null. Also, the
2202     // dynamic allocation call could be either of the operands.
2203     Value *MI = nullptr;
2204     if (isAllocLikeFn(LHS, TLI) && llvm::isKnownNonNullAt(RHS, CxtI, DT))
2205       MI = LHS;
2206     else if (isAllocLikeFn(RHS, TLI) && llvm::isKnownNonNullAt(LHS, CxtI, DT))
2207       MI = RHS;
2208     // FIXME: We should also fold the compare when the pointer escapes, but the
2209     // compare dominates the pointer escape
2210     if (MI && !PointerMayBeCaptured(MI, true, true))
2211       return ConstantInt::get(GetCompareTy(LHS),
2212                               CmpInst::isFalseWhenEqual(Pred));
2213   }
2214 
2215   // Otherwise, fail.
2216   return nullptr;
2217 }
2218 
2219 /// Fold an icmp when its operands have i1 scalar type.
2220 static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS,
2221                                   Value *RHS, const SimplifyQuery &Q) {
2222   Type *ITy = GetCompareTy(LHS); // The return type.
2223   Type *OpTy = LHS->getType();   // The operand type.
2224   if (!OpTy->getScalarType()->isIntegerTy(1))
2225     return nullptr;
2226 
2227   switch (Pred) {
2228   default:
2229     break;
2230   case ICmpInst::ICMP_EQ:
2231     // X == 1 -> X
2232     if (match(RHS, m_One()))
2233       return LHS;
2234     break;
2235   case ICmpInst::ICMP_NE:
2236     // X != 0 -> X
2237     if (match(RHS, m_Zero()))
2238       return LHS;
2239     break;
2240   case ICmpInst::ICMP_UGT:
2241     // X >u 0 -> X
2242     if (match(RHS, m_Zero()))
2243       return LHS;
2244     break;
2245   case ICmpInst::ICMP_UGE:
2246     // X >=u 1 -> X
2247     if (match(RHS, m_One()))
2248       return LHS;
2249     if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
2250       return getTrue(ITy);
2251     break;
2252   case ICmpInst::ICMP_SGE:
2253     /// For signed comparison, the values for an i1 are 0 and -1
2254     /// respectively. This maps into a truth table of:
2255     /// LHS | RHS | LHS >=s RHS   | LHS implies RHS
2256     ///  0  |  0  |  1 (0 >= 0)   |  1
2257     ///  0  |  1  |  1 (0 >= -1)  |  1
2258     ///  1  |  0  |  0 (-1 >= 0)  |  0
2259     ///  1  |  1  |  1 (-1 >= -1) |  1
2260     if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
2261       return getTrue(ITy);
2262     break;
2263   case ICmpInst::ICMP_SLT:
2264     // X <s 0 -> X
2265     if (match(RHS, m_Zero()))
2266       return LHS;
2267     break;
2268   case ICmpInst::ICMP_SLE:
2269     // X <=s -1 -> X
2270     if (match(RHS, m_One()))
2271       return LHS;
2272     break;
2273   case ICmpInst::ICMP_ULE:
2274     if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
2275       return getTrue(ITy);
2276     break;
2277   }
2278 
2279   return nullptr;
2280 }
2281 
2282 /// Try hard to fold icmp with zero RHS because this is a common case.
2283 static Value *simplifyICmpWithZero(CmpInst::Predicate Pred, Value *LHS,
2284                                    Value *RHS, const SimplifyQuery &Q) {
2285   if (!match(RHS, m_Zero()))
2286     return nullptr;
2287 
2288   Type *ITy = GetCompareTy(LHS); // The return type.
2289   bool LHSKnownNonNegative, LHSKnownNegative;
2290   switch (Pred) {
2291   default:
2292     llvm_unreachable("Unknown ICmp predicate!");
2293   case ICmpInst::ICMP_ULT:
2294     return getFalse(ITy);
2295   case ICmpInst::ICMP_UGE:
2296     return getTrue(ITy);
2297   case ICmpInst::ICMP_EQ:
2298   case ICmpInst::ICMP_ULE:
2299     if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2300       return getFalse(ITy);
2301     break;
2302   case ICmpInst::ICMP_NE:
2303   case ICmpInst::ICMP_UGT:
2304     if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2305       return getTrue(ITy);
2306     break;
2307   case ICmpInst::ICMP_SLT:
2308     ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2309                    Q.CxtI, Q.DT);
2310     if (LHSKnownNegative)
2311       return getTrue(ITy);
2312     if (LHSKnownNonNegative)
2313       return getFalse(ITy);
2314     break;
2315   case ICmpInst::ICMP_SLE:
2316     ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2317                    Q.CxtI, Q.DT);
2318     if (LHSKnownNegative)
2319       return getTrue(ITy);
2320     if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2321       return getFalse(ITy);
2322     break;
2323   case ICmpInst::ICMP_SGE:
2324     ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2325                    Q.CxtI, Q.DT);
2326     if (LHSKnownNegative)
2327       return getFalse(ITy);
2328     if (LHSKnownNonNegative)
2329       return getTrue(ITy);
2330     break;
2331   case ICmpInst::ICMP_SGT:
2332     ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
2333                    Q.CxtI, Q.DT);
2334     if (LHSKnownNegative)
2335       return getFalse(ITy);
2336     if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
2337       return getTrue(ITy);
2338     break;
2339   }
2340 
2341   return nullptr;
2342 }
2343 
2344 /// Many binary operators with a constant operand have an easy-to-compute
2345 /// range of outputs. This can be used to fold a comparison to always true or
2346 /// always false.
2347 static void setLimitsForBinOp(BinaryOperator &BO, APInt &Lower, APInt &Upper) {
2348   unsigned Width = Lower.getBitWidth();
2349   const APInt *C;
2350   switch (BO.getOpcode()) {
2351   case Instruction::Add:
2352     if (match(BO.getOperand(1), m_APInt(C)) && *C != 0) {
2353       // FIXME: If we have both nuw and nsw, we should reduce the range further.
2354       if (BO.hasNoUnsignedWrap()) {
2355         // 'add nuw x, C' produces [C, UINT_MAX].
2356         Lower = *C;
2357       } else if (BO.hasNoSignedWrap()) {
2358         if (C->isNegative()) {
2359           // 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C].
2360           Lower = APInt::getSignedMinValue(Width);
2361           Upper = APInt::getSignedMaxValue(Width) + *C + 1;
2362         } else {
2363           // 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX].
2364           Lower = APInt::getSignedMinValue(Width) + *C;
2365           Upper = APInt::getSignedMaxValue(Width) + 1;
2366         }
2367       }
2368     }
2369     break;
2370 
2371   case Instruction::And:
2372     if (match(BO.getOperand(1), m_APInt(C)))
2373       // 'and x, C' produces [0, C].
2374       Upper = *C + 1;
2375     break;
2376 
2377   case Instruction::Or:
2378     if (match(BO.getOperand(1), m_APInt(C)))
2379       // 'or x, C' produces [C, UINT_MAX].
2380       Lower = *C;
2381     break;
2382 
2383   case Instruction::AShr:
2384     if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) {
2385       // 'ashr x, C' produces [INT_MIN >> C, INT_MAX >> C].
2386       Lower = APInt::getSignedMinValue(Width).ashr(*C);
2387       Upper = APInt::getSignedMaxValue(Width).ashr(*C) + 1;
2388     } else if (match(BO.getOperand(0), m_APInt(C))) {
2389       unsigned ShiftAmount = Width - 1;
2390       if (*C != 0 && BO.isExact())
2391         ShiftAmount = C->countTrailingZeros();
2392       if (C->isNegative()) {
2393         // 'ashr C, x' produces [C, C >> (Width-1)]
2394         Lower = *C;
2395         Upper = C->ashr(ShiftAmount) + 1;
2396       } else {
2397         // 'ashr C, x' produces [C >> (Width-1), C]
2398         Lower = C->ashr(ShiftAmount);
2399         Upper = *C + 1;
2400       }
2401     }
2402     break;
2403 
2404   case Instruction::LShr:
2405     if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) {
2406       // 'lshr x, C' produces [0, UINT_MAX >> C].
2407       Upper = APInt::getAllOnesValue(Width).lshr(*C) + 1;
2408     } else if (match(BO.getOperand(0), m_APInt(C))) {
2409       // 'lshr C, x' produces [C >> (Width-1), C].
2410       unsigned ShiftAmount = Width - 1;
2411       if (*C != 0 && BO.isExact())
2412         ShiftAmount = C->countTrailingZeros();
2413       Lower = C->lshr(ShiftAmount);
2414       Upper = *C + 1;
2415     }
2416     break;
2417 
2418   case Instruction::Shl:
2419     if (match(BO.getOperand(0), m_APInt(C))) {
2420       if (BO.hasNoUnsignedWrap()) {
2421         // 'shl nuw C, x' produces [C, C << CLZ(C)]
2422         Lower = *C;
2423         Upper = Lower.shl(Lower.countLeadingZeros()) + 1;
2424       } else if (BO.hasNoSignedWrap()) { // TODO: What if both nuw+nsw?
2425         if (C->isNegative()) {
2426           // 'shl nsw C, x' produces [C << CLO(C)-1, C]
2427           unsigned ShiftAmount = C->countLeadingOnes() - 1;
2428           Lower = C->shl(ShiftAmount);
2429           Upper = *C + 1;
2430         } else {
2431           // 'shl nsw C, x' produces [C, C << CLZ(C)-1]
2432           unsigned ShiftAmount = C->countLeadingZeros() - 1;
2433           Lower = *C;
2434           Upper = C->shl(ShiftAmount) + 1;
2435         }
2436       }
2437     }
2438     break;
2439 
2440   case Instruction::SDiv:
2441     if (match(BO.getOperand(1), m_APInt(C))) {
2442       APInt IntMin = APInt::getSignedMinValue(Width);
2443       APInt IntMax = APInt::getSignedMaxValue(Width);
2444       if (C->isAllOnesValue()) {
2445         // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
2446         //    where C != -1 and C != 0 and C != 1
2447         Lower = IntMin + 1;
2448         Upper = IntMax + 1;
2449       } else if (C->countLeadingZeros() < Width - 1) {
2450         // 'sdiv x, C' produces [INT_MIN / C, INT_MAX / C]
2451         //    where C != -1 and C != 0 and C != 1
2452         Lower = IntMin.sdiv(*C);
2453         Upper = IntMax.sdiv(*C);
2454         if (Lower.sgt(Upper))
2455           std::swap(Lower, Upper);
2456         Upper = Upper + 1;
2457         assert(Upper != Lower && "Upper part of range has wrapped!");
2458       }
2459     } else if (match(BO.getOperand(0), m_APInt(C))) {
2460       if (C->isMinSignedValue()) {
2461         // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
2462         Lower = *C;
2463         Upper = Lower.lshr(1) + 1;
2464       } else {
2465         // 'sdiv C, x' produces [-|C|, |C|].
2466         Upper = C->abs() + 1;
2467         Lower = (-Upper) + 1;
2468       }
2469     }
2470     break;
2471 
2472   case Instruction::UDiv:
2473     if (match(BO.getOperand(1), m_APInt(C)) && *C != 0) {
2474       // 'udiv x, C' produces [0, UINT_MAX / C].
2475       Upper = APInt::getMaxValue(Width).udiv(*C) + 1;
2476     } else if (match(BO.getOperand(0), m_APInt(C))) {
2477       // 'udiv C, x' produces [0, C].
2478       Upper = *C + 1;
2479     }
2480     break;
2481 
2482   case Instruction::SRem:
2483     if (match(BO.getOperand(1), m_APInt(C))) {
2484       // 'srem x, C' produces (-|C|, |C|).
2485       Upper = C->abs();
2486       Lower = (-Upper) + 1;
2487     }
2488     break;
2489 
2490   case Instruction::URem:
2491     if (match(BO.getOperand(1), m_APInt(C)))
2492       // 'urem x, C' produces [0, C).
2493       Upper = *C;
2494     break;
2495 
2496   default:
2497     break;
2498   }
2499 }
2500 
2501 static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS,
2502                                        Value *RHS) {
2503   const APInt *C;
2504   if (!match(RHS, m_APInt(C)))
2505     return nullptr;
2506 
2507   // Rule out tautological comparisons (eg., ult 0 or uge 0).
2508   ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C);
2509   if (RHS_CR.isEmptySet())
2510     return ConstantInt::getFalse(GetCompareTy(RHS));
2511   if (RHS_CR.isFullSet())
2512     return ConstantInt::getTrue(GetCompareTy(RHS));
2513 
2514   // Find the range of possible values for binary operators.
2515   unsigned Width = C->getBitWidth();
2516   APInt Lower = APInt(Width, 0);
2517   APInt Upper = APInt(Width, 0);
2518   if (auto *BO = dyn_cast<BinaryOperator>(LHS))
2519     setLimitsForBinOp(*BO, Lower, Upper);
2520 
2521   ConstantRange LHS_CR =
2522       Lower != Upper ? ConstantRange(Lower, Upper) : ConstantRange(Width, true);
2523 
2524   if (auto *I = dyn_cast<Instruction>(LHS))
2525     if (auto *Ranges = I->getMetadata(LLVMContext::MD_range))
2526       LHS_CR = LHS_CR.intersectWith(getConstantRangeFromMetadata(*Ranges));
2527 
2528   if (!LHS_CR.isFullSet()) {
2529     if (RHS_CR.contains(LHS_CR))
2530       return ConstantInt::getTrue(GetCompareTy(RHS));
2531     if (RHS_CR.inverse().contains(LHS_CR))
2532       return ConstantInt::getFalse(GetCompareTy(RHS));
2533   }
2534 
2535   return nullptr;
2536 }
2537 
2538 /// TODO: A large part of this logic is duplicated in InstCombine's
2539 /// foldICmpBinOp(). We should be able to share that and avoid the code
2540 /// duplication.
2541 static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS,
2542                                     Value *RHS, const SimplifyQuery &Q,
2543                                     unsigned MaxRecurse) {
2544   Type *ITy = GetCompareTy(LHS); // The return type.
2545 
2546   BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
2547   BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
2548   if (MaxRecurse && (LBO || RBO)) {
2549     // Analyze the case when either LHS or RHS is an add instruction.
2550     Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2551     // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
2552     bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
2553     if (LBO && LBO->getOpcode() == Instruction::Add) {
2554       A = LBO->getOperand(0);
2555       B = LBO->getOperand(1);
2556       NoLHSWrapProblem =
2557           ICmpInst::isEquality(Pred) ||
2558           (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
2559           (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
2560     }
2561     if (RBO && RBO->getOpcode() == Instruction::Add) {
2562       C = RBO->getOperand(0);
2563       D = RBO->getOperand(1);
2564       NoRHSWrapProblem =
2565           ICmpInst::isEquality(Pred) ||
2566           (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
2567           (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2568     }
2569 
2570     // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2571     if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2572       if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2573                                       Constant::getNullValue(RHS->getType()), Q,
2574                                       MaxRecurse - 1))
2575         return V;
2576 
2577     // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2578     if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2579       if (Value *V =
2580               SimplifyICmpInst(Pred, Constant::getNullValue(LHS->getType()),
2581                                C == LHS ? D : C, Q, MaxRecurse - 1))
2582         return V;
2583 
2584     // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2585     if (A && C && (A == C || A == D || B == C || B == D) && NoLHSWrapProblem &&
2586         NoRHSWrapProblem) {
2587       // Determine Y and Z in the form icmp (X+Y), (X+Z).
2588       Value *Y, *Z;
2589       if (A == C) {
2590         // C + B == C + D  ->  B == D
2591         Y = B;
2592         Z = D;
2593       } else if (A == D) {
2594         // D + B == C + D  ->  B == C
2595         Y = B;
2596         Z = C;
2597       } else if (B == C) {
2598         // A + C == C + D  ->  A == D
2599         Y = A;
2600         Z = D;
2601       } else {
2602         assert(B == D);
2603         // A + D == C + D  ->  A == C
2604         Y = A;
2605         Z = C;
2606       }
2607       if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1))
2608         return V;
2609     }
2610   }
2611 
2612   {
2613     Value *Y = nullptr;
2614     // icmp pred (or X, Y), X
2615     if (LBO && match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) {
2616       if (Pred == ICmpInst::ICMP_ULT)
2617         return getFalse(ITy);
2618       if (Pred == ICmpInst::ICMP_UGE)
2619         return getTrue(ITy);
2620 
2621       if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) {
2622         bool RHSKnownNonNegative, RHSKnownNegative;
2623         bool YKnownNonNegative, YKnownNegative;
2624         ComputeSignBit(RHS, RHSKnownNonNegative, RHSKnownNegative, Q.DL, 0,
2625                        Q.AC, Q.CxtI, Q.DT);
2626         ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, Q.DL, 0, Q.AC,
2627                        Q.CxtI, Q.DT);
2628         if (RHSKnownNonNegative && YKnownNegative)
2629           return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy);
2630         if (RHSKnownNegative || YKnownNonNegative)
2631           return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy);
2632       }
2633     }
2634     // icmp pred X, (or X, Y)
2635     if (RBO && match(RBO, m_c_Or(m_Value(Y), m_Specific(LHS)))) {
2636       if (Pred == ICmpInst::ICMP_ULE)
2637         return getTrue(ITy);
2638       if (Pred == ICmpInst::ICMP_UGT)
2639         return getFalse(ITy);
2640 
2641       if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLE) {
2642         bool LHSKnownNonNegative, LHSKnownNegative;
2643         bool YKnownNonNegative, YKnownNegative;
2644         ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0,
2645                        Q.AC, Q.CxtI, Q.DT);
2646         ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, Q.DL, 0, Q.AC,
2647                        Q.CxtI, Q.DT);
2648         if (LHSKnownNonNegative && YKnownNegative)
2649           return Pred == ICmpInst::ICMP_SGT ? getTrue(ITy) : getFalse(ITy);
2650         if (LHSKnownNegative || YKnownNonNegative)
2651           return Pred == ICmpInst::ICMP_SGT ? getFalse(ITy) : getTrue(ITy);
2652       }
2653     }
2654   }
2655 
2656   // icmp pred (and X, Y), X
2657   if (LBO && match(LBO, m_CombineOr(m_And(m_Value(), m_Specific(RHS)),
2658                                     m_And(m_Specific(RHS), m_Value())))) {
2659     if (Pred == ICmpInst::ICMP_UGT)
2660       return getFalse(ITy);
2661     if (Pred == ICmpInst::ICMP_ULE)
2662       return getTrue(ITy);
2663   }
2664   // icmp pred X, (and X, Y)
2665   if (RBO && match(RBO, m_CombineOr(m_And(m_Value(), m_Specific(LHS)),
2666                                     m_And(m_Specific(LHS), m_Value())))) {
2667     if (Pred == ICmpInst::ICMP_UGE)
2668       return getTrue(ITy);
2669     if (Pred == ICmpInst::ICMP_ULT)
2670       return getFalse(ITy);
2671   }
2672 
2673   // 0 - (zext X) pred C
2674   if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
2675     if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
2676       if (RHSC->getValue().isStrictlyPositive()) {
2677         if (Pred == ICmpInst::ICMP_SLT)
2678           return ConstantInt::getTrue(RHSC->getContext());
2679         if (Pred == ICmpInst::ICMP_SGE)
2680           return ConstantInt::getFalse(RHSC->getContext());
2681         if (Pred == ICmpInst::ICMP_EQ)
2682           return ConstantInt::getFalse(RHSC->getContext());
2683         if (Pred == ICmpInst::ICMP_NE)
2684           return ConstantInt::getTrue(RHSC->getContext());
2685       }
2686       if (RHSC->getValue().isNonNegative()) {
2687         if (Pred == ICmpInst::ICMP_SLE)
2688           return ConstantInt::getTrue(RHSC->getContext());
2689         if (Pred == ICmpInst::ICMP_SGT)
2690           return ConstantInt::getFalse(RHSC->getContext());
2691       }
2692     }
2693   }
2694 
2695   // icmp pred (urem X, Y), Y
2696   if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2697     bool KnownNonNegative, KnownNegative;
2698     switch (Pred) {
2699     default:
2700       break;
2701     case ICmpInst::ICMP_SGT:
2702     case ICmpInst::ICMP_SGE:
2703       ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2704                      Q.CxtI, Q.DT);
2705       if (!KnownNonNegative)
2706         break;
2707       LLVM_FALLTHROUGH;
2708     case ICmpInst::ICMP_EQ:
2709     case ICmpInst::ICMP_UGT:
2710     case ICmpInst::ICMP_UGE:
2711       return getFalse(ITy);
2712     case ICmpInst::ICMP_SLT:
2713     case ICmpInst::ICMP_SLE:
2714       ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2715                      Q.CxtI, Q.DT);
2716       if (!KnownNonNegative)
2717         break;
2718       LLVM_FALLTHROUGH;
2719     case ICmpInst::ICMP_NE:
2720     case ICmpInst::ICMP_ULT:
2721     case ICmpInst::ICMP_ULE:
2722       return getTrue(ITy);
2723     }
2724   }
2725 
2726   // icmp pred X, (urem Y, X)
2727   if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2728     bool KnownNonNegative, KnownNegative;
2729     switch (Pred) {
2730     default:
2731       break;
2732     case ICmpInst::ICMP_SGT:
2733     case ICmpInst::ICMP_SGE:
2734       ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2735                      Q.CxtI, Q.DT);
2736       if (!KnownNonNegative)
2737         break;
2738       LLVM_FALLTHROUGH;
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       ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
2746                      Q.CxtI, Q.DT);
2747       if (!KnownNonNegative)
2748         break;
2749       LLVM_FALLTHROUGH;
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 == 1 || !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 == 1) {
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))
2822         break;
2823       LLVM_FALLTHROUGH;
2824     case Instruction::SDiv:
2825     case Instruction::AShr:
2826       if (!LBO->isExact() || !RBO->isExact())
2827         break;
2828       if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2829                                       RBO->getOperand(0), Q, MaxRecurse - 1))
2830         return V;
2831       break;
2832     case Instruction::Shl: {
2833       bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2834       bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2835       if (!NUW && !NSW)
2836         break;
2837       if (!NSW && ICmpInst::isSigned(Pred))
2838         break;
2839       if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2840                                       RBO->getOperand(0), Q, MaxRecurse - 1))
2841         return V;
2842       break;
2843     }
2844     }
2845   }
2846   return nullptr;
2847 }
2848 
2849 /// Simplify integer comparisons where at least one operand of the compare
2850 /// matches an integer min/max idiom.
2851 static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS,
2852                                      Value *RHS, const SimplifyQuery &Q,
2853                                      unsigned MaxRecurse) {
2854   Type *ITy = GetCompareTy(LHS); // The return type.
2855   Value *A, *B;
2856   CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2857   CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2858 
2859   // Signed variants on "max(a,b)>=a -> true".
2860   if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2861     if (A != RHS)
2862       std::swap(A, B);       // smax(A, B) pred A.
2863     EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2864     // We analyze this as smax(A, B) pred A.
2865     P = Pred;
2866   } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2867              (A == LHS || B == LHS)) {
2868     if (A != LHS)
2869       std::swap(A, B);       // A pred smax(A, B).
2870     EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2871     // We analyze this as smax(A, B) swapped-pred A.
2872     P = CmpInst::getSwappedPredicate(Pred);
2873   } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2874              (A == RHS || B == RHS)) {
2875     if (A != RHS)
2876       std::swap(A, B);       // smin(A, B) pred A.
2877     EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2878     // We analyze this as smax(-A, -B) swapped-pred -A.
2879     // Note that we do not need to actually form -A or -B thanks to EqP.
2880     P = CmpInst::getSwappedPredicate(Pred);
2881   } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2882              (A == LHS || B == LHS)) {
2883     if (A != LHS)
2884       std::swap(A, B);       // A pred smin(A, B).
2885     EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2886     // We analyze this as smax(-A, -B) pred -A.
2887     // Note that we do not need to actually form -A or -B thanks to EqP.
2888     P = Pred;
2889   }
2890   if (P != CmpInst::BAD_ICMP_PREDICATE) {
2891     // Cases correspond to "max(A, B) p A".
2892     switch (P) {
2893     default:
2894       break;
2895     case CmpInst::ICMP_EQ:
2896     case CmpInst::ICMP_SLE:
2897       // Equivalent to "A EqP B".  This may be the same as the condition tested
2898       // in the max/min; if so, we can just return that.
2899       if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2900         return V;
2901       if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2902         return V;
2903       // Otherwise, see if "A EqP B" simplifies.
2904       if (MaxRecurse)
2905         if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
2906           return V;
2907       break;
2908     case CmpInst::ICMP_NE:
2909     case CmpInst::ICMP_SGT: {
2910       CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2911       // Equivalent to "A InvEqP B".  This may be the same as the condition
2912       // tested in the max/min; if so, we can just return that.
2913       if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2914         return V;
2915       if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2916         return V;
2917       // Otherwise, see if "A InvEqP B" simplifies.
2918       if (MaxRecurse)
2919         if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
2920           return V;
2921       break;
2922     }
2923     case CmpInst::ICMP_SGE:
2924       // Always true.
2925       return getTrue(ITy);
2926     case CmpInst::ICMP_SLT:
2927       // Always false.
2928       return getFalse(ITy);
2929     }
2930   }
2931 
2932   // Unsigned variants on "max(a,b)>=a -> true".
2933   P = CmpInst::BAD_ICMP_PREDICATE;
2934   if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2935     if (A != RHS)
2936       std::swap(A, B);       // umax(A, B) pred A.
2937     EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2938     // We analyze this as umax(A, B) pred A.
2939     P = Pred;
2940   } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2941              (A == LHS || B == LHS)) {
2942     if (A != LHS)
2943       std::swap(A, B);       // A pred umax(A, B).
2944     EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2945     // We analyze this as umax(A, B) swapped-pred A.
2946     P = CmpInst::getSwappedPredicate(Pred);
2947   } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2948              (A == RHS || B == RHS)) {
2949     if (A != RHS)
2950       std::swap(A, B);       // umin(A, B) pred A.
2951     EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2952     // We analyze this as umax(-A, -B) swapped-pred -A.
2953     // Note that we do not need to actually form -A or -B thanks to EqP.
2954     P = CmpInst::getSwappedPredicate(Pred);
2955   } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2956              (A == LHS || B == LHS)) {
2957     if (A != LHS)
2958       std::swap(A, B);       // A pred umin(A, B).
2959     EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2960     // We analyze this as umax(-A, -B) pred -A.
2961     // Note that we do not need to actually form -A or -B thanks to EqP.
2962     P = Pred;
2963   }
2964   if (P != CmpInst::BAD_ICMP_PREDICATE) {
2965     // Cases correspond to "max(A, B) p A".
2966     switch (P) {
2967     default:
2968       break;
2969     case CmpInst::ICMP_EQ:
2970     case CmpInst::ICMP_ULE:
2971       // Equivalent to "A EqP B".  This may be the same as the condition tested
2972       // in the max/min; if so, we can just return that.
2973       if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2974         return V;
2975       if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2976         return V;
2977       // Otherwise, see if "A EqP B" simplifies.
2978       if (MaxRecurse)
2979         if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
2980           return V;
2981       break;
2982     case CmpInst::ICMP_NE:
2983     case CmpInst::ICMP_UGT: {
2984       CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2985       // Equivalent to "A InvEqP B".  This may be the same as the condition
2986       // tested in the max/min; if so, we can just return that.
2987       if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2988         return V;
2989       if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2990         return V;
2991       // Otherwise, see if "A InvEqP B" simplifies.
2992       if (MaxRecurse)
2993         if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
2994           return V;
2995       break;
2996     }
2997     case CmpInst::ICMP_UGE:
2998       // Always true.
2999       return getTrue(ITy);
3000     case CmpInst::ICMP_ULT:
3001       // Always false.
3002       return getFalse(ITy);
3003     }
3004   }
3005 
3006   // Variants on "max(x,y) >= min(x,z)".
3007   Value *C, *D;
3008   if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
3009       match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
3010       (A == C || A == D || B == C || B == D)) {
3011     // max(x, ?) pred min(x, ?).
3012     if (Pred == CmpInst::ICMP_SGE)
3013       // Always true.
3014       return getTrue(ITy);
3015     if (Pred == CmpInst::ICMP_SLT)
3016       // Always false.
3017       return getFalse(ITy);
3018   } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
3019              match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
3020              (A == C || A == D || B == C || B == D)) {
3021     // min(x, ?) pred max(x, ?).
3022     if (Pred == CmpInst::ICMP_SLE)
3023       // Always true.
3024       return getTrue(ITy);
3025     if (Pred == CmpInst::ICMP_SGT)
3026       // Always false.
3027       return getFalse(ITy);
3028   } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
3029              match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
3030              (A == C || A == D || B == C || B == D)) {
3031     // max(x, ?) pred min(x, ?).
3032     if (Pred == CmpInst::ICMP_UGE)
3033       // Always true.
3034       return getTrue(ITy);
3035     if (Pred == CmpInst::ICMP_ULT)
3036       // Always false.
3037       return getFalse(ITy);
3038   } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
3039              match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
3040              (A == C || A == D || B == C || B == D)) {
3041     // min(x, ?) pred max(x, ?).
3042     if (Pred == CmpInst::ICMP_ULE)
3043       // Always true.
3044       return getTrue(ITy);
3045     if (Pred == CmpInst::ICMP_UGT)
3046       // Always false.
3047       return getFalse(ITy);
3048   }
3049 
3050   return nullptr;
3051 }
3052 
3053 /// Given operands for an ICmpInst, see if we can fold the result.
3054 /// If not, this returns null.
3055 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3056                                const SimplifyQuery &Q, unsigned MaxRecurse) {
3057   CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3058   assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
3059 
3060   if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3061     if (Constant *CRHS = dyn_cast<Constant>(RHS))
3062       return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3063 
3064     // If we have a constant, make sure it is on the RHS.
3065     std::swap(LHS, RHS);
3066     Pred = CmpInst::getSwappedPredicate(Pred);
3067   }
3068 
3069   Type *ITy = GetCompareTy(LHS); // The return type.
3070 
3071   // icmp X, X -> true/false
3072   // X icmp undef -> true/false.  For example, icmp ugt %X, undef -> false
3073   // because X could be 0.
3074   if (LHS == RHS || isa<UndefValue>(RHS))
3075     return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
3076 
3077   if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
3078     return V;
3079 
3080   if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
3081     return V;
3082 
3083   if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS))
3084     return V;
3085 
3086   // If both operands have range metadata, use the metadata
3087   // to simplify the comparison.
3088   if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) {
3089     auto RHS_Instr = cast<Instruction>(RHS);
3090     auto LHS_Instr = cast<Instruction>(LHS);
3091 
3092     if (RHS_Instr->getMetadata(LLVMContext::MD_range) &&
3093         LHS_Instr->getMetadata(LLVMContext::MD_range)) {
3094       auto RHS_CR = getConstantRangeFromMetadata(
3095           *RHS_Instr->getMetadata(LLVMContext::MD_range));
3096       auto LHS_CR = getConstantRangeFromMetadata(
3097           *LHS_Instr->getMetadata(LLVMContext::MD_range));
3098 
3099       auto Satisfied_CR = ConstantRange::makeSatisfyingICmpRegion(Pred, RHS_CR);
3100       if (Satisfied_CR.contains(LHS_CR))
3101         return ConstantInt::getTrue(RHS->getContext());
3102 
3103       auto InversedSatisfied_CR = ConstantRange::makeSatisfyingICmpRegion(
3104                 CmpInst::getInversePredicate(Pred), RHS_CR);
3105       if (InversedSatisfied_CR.contains(LHS_CR))
3106         return ConstantInt::getFalse(RHS->getContext());
3107     }
3108   }
3109 
3110   // Compare of cast, for example (zext X) != 0 -> X != 0
3111   if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
3112     Instruction *LI = cast<CastInst>(LHS);
3113     Value *SrcOp = LI->getOperand(0);
3114     Type *SrcTy = SrcOp->getType();
3115     Type *DstTy = LI->getType();
3116 
3117     // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
3118     // if the integer type is the same size as the pointer type.
3119     if (MaxRecurse && isa<PtrToIntInst>(LI) &&
3120         Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
3121       if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
3122         // Transfer the cast to the constant.
3123         if (Value *V = SimplifyICmpInst(Pred, SrcOp,
3124                                         ConstantExpr::getIntToPtr(RHSC, SrcTy),
3125                                         Q, MaxRecurse-1))
3126           return V;
3127       } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
3128         if (RI->getOperand(0)->getType() == SrcTy)
3129           // Compare without the cast.
3130           if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
3131                                           Q, MaxRecurse-1))
3132             return V;
3133       }
3134     }
3135 
3136     if (isa<ZExtInst>(LHS)) {
3137       // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
3138       // same type.
3139       if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
3140         if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3141           // Compare X and Y.  Note that signed predicates become unsigned.
3142           if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
3143                                           SrcOp, RI->getOperand(0), Q,
3144                                           MaxRecurse-1))
3145             return V;
3146       }
3147       // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
3148       // too.  If not, then try to deduce the result of the comparison.
3149       else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
3150         // Compute the constant that would happen if we truncated to SrcTy then
3151         // reextended to DstTy.
3152         Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
3153         Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
3154 
3155         // If the re-extended constant didn't change then this is effectively
3156         // also a case of comparing two zero-extended values.
3157         if (RExt == CI && MaxRecurse)
3158           if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
3159                                         SrcOp, Trunc, Q, MaxRecurse-1))
3160             return V;
3161 
3162         // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
3163         // there.  Use this to work out the result of the comparison.
3164         if (RExt != CI) {
3165           switch (Pred) {
3166           default: llvm_unreachable("Unknown ICmp predicate!");
3167           // LHS <u RHS.
3168           case ICmpInst::ICMP_EQ:
3169           case ICmpInst::ICMP_UGT:
3170           case ICmpInst::ICMP_UGE:
3171             return ConstantInt::getFalse(CI->getContext());
3172 
3173           case ICmpInst::ICMP_NE:
3174           case ICmpInst::ICMP_ULT:
3175           case ICmpInst::ICMP_ULE:
3176             return ConstantInt::getTrue(CI->getContext());
3177 
3178           // LHS is non-negative.  If RHS is negative then LHS >s LHS.  If RHS
3179           // is non-negative then LHS <s RHS.
3180           case ICmpInst::ICMP_SGT:
3181           case ICmpInst::ICMP_SGE:
3182             return CI->getValue().isNegative() ?
3183               ConstantInt::getTrue(CI->getContext()) :
3184               ConstantInt::getFalse(CI->getContext());
3185 
3186           case ICmpInst::ICMP_SLT:
3187           case ICmpInst::ICMP_SLE:
3188             return CI->getValue().isNegative() ?
3189               ConstantInt::getFalse(CI->getContext()) :
3190               ConstantInt::getTrue(CI->getContext());
3191           }
3192         }
3193       }
3194     }
3195 
3196     if (isa<SExtInst>(LHS)) {
3197       // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
3198       // same type.
3199       if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
3200         if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3201           // Compare X and Y.  Note that the predicate does not change.
3202           if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
3203                                           Q, MaxRecurse-1))
3204             return V;
3205       }
3206       // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
3207       // too.  If not, then try to deduce the result of the comparison.
3208       else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
3209         // Compute the constant that would happen if we truncated to SrcTy then
3210         // reextended to DstTy.
3211         Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
3212         Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
3213 
3214         // If the re-extended constant didn't change then this is effectively
3215         // also a case of comparing two sign-extended values.
3216         if (RExt == CI && MaxRecurse)
3217           if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
3218             return V;
3219 
3220         // Otherwise the upper bits of LHS are all equal, while RHS has varying
3221         // bits there.  Use this to work out the result of the comparison.
3222         if (RExt != CI) {
3223           switch (Pred) {
3224           default: llvm_unreachable("Unknown ICmp predicate!");
3225           case ICmpInst::ICMP_EQ:
3226             return ConstantInt::getFalse(CI->getContext());
3227           case ICmpInst::ICMP_NE:
3228             return ConstantInt::getTrue(CI->getContext());
3229 
3230           // If RHS is non-negative then LHS <s RHS.  If RHS is negative then
3231           // LHS >s RHS.
3232           case ICmpInst::ICMP_SGT:
3233           case ICmpInst::ICMP_SGE:
3234             return CI->getValue().isNegative() ?
3235               ConstantInt::getTrue(CI->getContext()) :
3236               ConstantInt::getFalse(CI->getContext());
3237           case ICmpInst::ICMP_SLT:
3238           case ICmpInst::ICMP_SLE:
3239             return CI->getValue().isNegative() ?
3240               ConstantInt::getFalse(CI->getContext()) :
3241               ConstantInt::getTrue(CI->getContext());
3242 
3243           // If LHS is non-negative then LHS <u RHS.  If LHS is negative then
3244           // LHS >u RHS.
3245           case ICmpInst::ICMP_UGT:
3246           case ICmpInst::ICMP_UGE:
3247             // Comparison is true iff the LHS <s 0.
3248             if (MaxRecurse)
3249               if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
3250                                               Constant::getNullValue(SrcTy),
3251                                               Q, MaxRecurse-1))
3252                 return V;
3253             break;
3254           case ICmpInst::ICMP_ULT:
3255           case ICmpInst::ICMP_ULE:
3256             // Comparison is true iff the LHS >=s 0.
3257             if (MaxRecurse)
3258               if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
3259                                               Constant::getNullValue(SrcTy),
3260                                               Q, MaxRecurse-1))
3261                 return V;
3262             break;
3263           }
3264         }
3265       }
3266     }
3267   }
3268 
3269   // icmp eq|ne X, Y -> false|true if X != Y
3270   if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) &&
3271       isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT)) {
3272     LLVMContext &Ctx = LHS->getType()->getContext();
3273     return Pred == ICmpInst::ICMP_NE ?
3274       ConstantInt::getTrue(Ctx) : ConstantInt::getFalse(Ctx);
3275   }
3276 
3277   if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse))
3278     return V;
3279 
3280   if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse))
3281     return V;
3282 
3283   // Simplify comparisons of related pointers using a powerful, recursive
3284   // GEP-walk when we have target data available..
3285   if (LHS->getType()->isPointerTy())
3286     if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.CxtI, LHS, RHS))
3287       return C;
3288   if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS))
3289     if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS))
3290       if (Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) ==
3291               Q.DL.getTypeSizeInBits(CLHS->getType()) &&
3292           Q.DL.getTypeSizeInBits(CRHS->getPointerOperandType()) ==
3293               Q.DL.getTypeSizeInBits(CRHS->getType()))
3294         if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.CxtI,
3295                                          CLHS->getPointerOperand(),
3296                                          CRHS->getPointerOperand()))
3297           return C;
3298 
3299   if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
3300     if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
3301       if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
3302           GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
3303           (ICmpInst::isEquality(Pred) ||
3304            (GLHS->isInBounds() && GRHS->isInBounds() &&
3305             Pred == ICmpInst::getSignedPredicate(Pred)))) {
3306         // The bases are equal and the indices are constant.  Build a constant
3307         // expression GEP with the same indices and a null base pointer to see
3308         // what constant folding can make out of it.
3309         Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
3310         SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
3311         Constant *NewLHS = ConstantExpr::getGetElementPtr(
3312             GLHS->getSourceElementType(), Null, IndicesLHS);
3313 
3314         SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
3315         Constant *NewRHS = ConstantExpr::getGetElementPtr(
3316             GLHS->getSourceElementType(), Null, IndicesRHS);
3317         return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
3318       }
3319     }
3320   }
3321 
3322   // If a bit is known to be zero for A and known to be one for B,
3323   // then A and B cannot be equal.
3324   if (ICmpInst::isEquality(Pred)) {
3325     const APInt *RHSVal;
3326     if (match(RHS, m_APInt(RHSVal))) {
3327       unsigned BitWidth = RHSVal->getBitWidth();
3328       KnownBits LHSKnown(BitWidth);
3329       computeKnownBits(LHS, LHSKnown, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
3330       if (LHSKnown.Zero.intersects(*RHSVal) ||
3331           !LHSKnown.One.isSubsetOf(*RHSVal))
3332         return Pred == ICmpInst::ICMP_EQ ? ConstantInt::getFalse(ITy)
3333                                          : ConstantInt::getTrue(ITy);
3334     }
3335   }
3336 
3337   // If the comparison is with the result of a select instruction, check whether
3338   // comparing with either branch of the select always yields the same value.
3339   if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3340     if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3341       return V;
3342 
3343   // If the comparison is with the result of a phi instruction, check whether
3344   // doing the compare with each incoming phi value yields a common result.
3345   if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3346     if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3347       return V;
3348 
3349   return nullptr;
3350 }
3351 
3352 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3353                               const SimplifyQuery &Q) {
3354   return ::SimplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
3355 }
3356 
3357 /// Given operands for an FCmpInst, see if we can fold the result.
3358 /// If not, this returns null.
3359 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3360                                FastMathFlags FMF, const SimplifyQuery &Q,
3361                                unsigned MaxRecurse) {
3362   CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
3363   assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
3364 
3365   if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3366     if (Constant *CRHS = dyn_cast<Constant>(RHS))
3367       return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3368 
3369     // If we have a constant, make sure it is on the RHS.
3370     std::swap(LHS, RHS);
3371     Pred = CmpInst::getSwappedPredicate(Pred);
3372   }
3373 
3374   // Fold trivial predicates.
3375   Type *RetTy = GetCompareTy(LHS);
3376   if (Pred == FCmpInst::FCMP_FALSE)
3377     return getFalse(RetTy);
3378   if (Pred == FCmpInst::FCMP_TRUE)
3379     return getTrue(RetTy);
3380 
3381   // UNO/ORD predicates can be trivially folded if NaNs are ignored.
3382   if (FMF.noNaNs()) {
3383     if (Pred == FCmpInst::FCMP_UNO)
3384       return getFalse(RetTy);
3385     if (Pred == FCmpInst::FCMP_ORD)
3386       return getTrue(RetTy);
3387   }
3388 
3389   // fcmp pred x, undef  and  fcmp pred undef, x
3390   // fold to true if unordered, false if ordered
3391   if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS)) {
3392     // Choosing NaN for the undef will always make unordered comparison succeed
3393     // and ordered comparison fail.
3394     return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
3395   }
3396 
3397   // fcmp x,x -> true/false.  Not all compares are foldable.
3398   if (LHS == RHS) {
3399     if (CmpInst::isTrueWhenEqual(Pred))
3400       return getTrue(RetTy);
3401     if (CmpInst::isFalseWhenEqual(Pred))
3402       return getFalse(RetTy);
3403   }
3404 
3405   // Handle fcmp with constant RHS
3406   const ConstantFP *CFP = nullptr;
3407   if (const auto *RHSC = dyn_cast<Constant>(RHS)) {
3408     if (RHS->getType()->isVectorTy())
3409       CFP = dyn_cast_or_null<ConstantFP>(RHSC->getSplatValue());
3410     else
3411       CFP = dyn_cast<ConstantFP>(RHSC);
3412   }
3413   if (CFP) {
3414     // If the constant is a nan, see if we can fold the comparison based on it.
3415     if (CFP->getValueAPF().isNaN()) {
3416       if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
3417         return getFalse(RetTy);
3418       assert(FCmpInst::isUnordered(Pred) &&
3419              "Comparison must be either ordered or unordered!");
3420       // True if unordered.
3421       return getTrue(RetTy);
3422     }
3423     // Check whether the constant is an infinity.
3424     if (CFP->getValueAPF().isInfinity()) {
3425       if (CFP->getValueAPF().isNegative()) {
3426         switch (Pred) {
3427         case FCmpInst::FCMP_OLT:
3428           // No value is ordered and less than negative infinity.
3429           return getFalse(RetTy);
3430         case FCmpInst::FCMP_UGE:
3431           // All values are unordered with or at least negative infinity.
3432           return getTrue(RetTy);
3433         default:
3434           break;
3435         }
3436       } else {
3437         switch (Pred) {
3438         case FCmpInst::FCMP_OGT:
3439           // No value is ordered and greater than infinity.
3440           return getFalse(RetTy);
3441         case FCmpInst::FCMP_ULE:
3442           // All values are unordered with and at most infinity.
3443           return getTrue(RetTy);
3444         default:
3445           break;
3446         }
3447       }
3448     }
3449     if (CFP->getValueAPF().isZero()) {
3450       switch (Pred) {
3451       case FCmpInst::FCMP_UGE:
3452         if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3453           return getTrue(RetTy);
3454         break;
3455       case FCmpInst::FCMP_OLT:
3456         // X < 0
3457         if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
3458           return getFalse(RetTy);
3459         break;
3460       default:
3461         break;
3462       }
3463     }
3464   }
3465 
3466   // If the comparison is with the result of a select instruction, check whether
3467   // comparing with either branch of the select always yields the same value.
3468   if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
3469     if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
3470       return V;
3471 
3472   // If the comparison is with the result of a phi instruction, check whether
3473   // doing the compare with each incoming phi value yields a common result.
3474   if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
3475     if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
3476       return V;
3477 
3478   return nullptr;
3479 }
3480 
3481 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
3482                               FastMathFlags FMF, const SimplifyQuery &Q) {
3483   return ::SimplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit);
3484 }
3485 
3486 /// See if V simplifies when its operand Op is replaced with RepOp.
3487 static const Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
3488                                            const SimplifyQuery &Q,
3489                                            unsigned MaxRecurse) {
3490   // Trivial replacement.
3491   if (V == Op)
3492     return RepOp;
3493 
3494   auto *I = dyn_cast<Instruction>(V);
3495   if (!I)
3496     return nullptr;
3497 
3498   // If this is a binary operator, try to simplify it with the replaced op.
3499   if (auto *B = dyn_cast<BinaryOperator>(I)) {
3500     // Consider:
3501     //   %cmp = icmp eq i32 %x, 2147483647
3502     //   %add = add nsw i32 %x, 1
3503     //   %sel = select i1 %cmp, i32 -2147483648, i32 %add
3504     //
3505     // We can't replace %sel with %add unless we strip away the flags.
3506     if (isa<OverflowingBinaryOperator>(B))
3507       if (B->hasNoSignedWrap() || B->hasNoUnsignedWrap())
3508         return nullptr;
3509     if (isa<PossiblyExactOperator>(B))
3510       if (B->isExact())
3511         return nullptr;
3512 
3513     if (MaxRecurse) {
3514       if (B->getOperand(0) == Op)
3515         return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), Q,
3516                              MaxRecurse - 1);
3517       if (B->getOperand(1) == Op)
3518         return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, Q,
3519                              MaxRecurse - 1);
3520     }
3521   }
3522 
3523   // Same for CmpInsts.
3524   if (CmpInst *C = dyn_cast<CmpInst>(I)) {
3525     if (MaxRecurse) {
3526       if (C->getOperand(0) == Op)
3527         return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), Q,
3528                                MaxRecurse - 1);
3529       if (C->getOperand(1) == Op)
3530         return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, Q,
3531                                MaxRecurse - 1);
3532     }
3533   }
3534 
3535   // TODO: We could hand off more cases to instsimplify here.
3536 
3537   // If all operands are constant after substituting Op for RepOp then we can
3538   // constant fold the instruction.
3539   if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) {
3540     // Build a list of all constant operands.
3541     SmallVector<Constant *, 8> ConstOps;
3542     for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
3543       if (I->getOperand(i) == Op)
3544         ConstOps.push_back(CRepOp);
3545       else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i)))
3546         ConstOps.push_back(COp);
3547       else
3548         break;
3549     }
3550 
3551     // All operands were constants, fold it.
3552     if (ConstOps.size() == I->getNumOperands()) {
3553       if (CmpInst *C = dyn_cast<CmpInst>(I))
3554         return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0],
3555                                                ConstOps[1], Q.DL, Q.TLI);
3556 
3557       if (LoadInst *LI = dyn_cast<LoadInst>(I))
3558         if (!LI->isVolatile())
3559           return ConstantFoldLoadFromConstPtr(ConstOps[0], LI->getType(), Q.DL);
3560 
3561       return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI);
3562     }
3563   }
3564 
3565   return nullptr;
3566 }
3567 
3568 /// Try to simplify a select instruction when its condition operand is an
3569 /// integer comparison where one operand of the compare is a constant.
3570 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X,
3571                                     const APInt *Y, bool TrueWhenUnset) {
3572   const APInt *C;
3573 
3574   // (X & Y) == 0 ? X & ~Y : X  --> X
3575   // (X & Y) != 0 ? X & ~Y : X  --> X & ~Y
3576   if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) &&
3577       *Y == ~*C)
3578     return TrueWhenUnset ? FalseVal : TrueVal;
3579 
3580   // (X & Y) == 0 ? X : X & ~Y  --> X & ~Y
3581   // (X & Y) != 0 ? X : X & ~Y  --> X
3582   if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) &&
3583       *Y == ~*C)
3584     return TrueWhenUnset ? FalseVal : TrueVal;
3585 
3586   if (Y->isPowerOf2()) {
3587     // (X & Y) == 0 ? X | Y : X  --> X | Y
3588     // (X & Y) != 0 ? X | Y : X  --> X
3589     if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) &&
3590         *Y == *C)
3591       return TrueWhenUnset ? TrueVal : FalseVal;
3592 
3593     // (X & Y) == 0 ? X : X | Y  --> X
3594     // (X & Y) != 0 ? X : X | Y  --> X | Y
3595     if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) &&
3596         *Y == *C)
3597       return TrueWhenUnset ? TrueVal : FalseVal;
3598   }
3599 
3600   return nullptr;
3601 }
3602 
3603 /// An alternative way to test if a bit is set or not uses sgt/slt instead of
3604 /// eq/ne.
3605 static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *TrueVal,
3606                                            Value *FalseVal,
3607                                            bool TrueWhenUnset) {
3608   unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits();
3609   if (!BitWidth)
3610     return nullptr;
3611 
3612   APInt MinSignedValue;
3613   Value *X;
3614   if (match(CmpLHS, m_Trunc(m_Value(X))) && (X == TrueVal || X == FalseVal)) {
3615     // icmp slt (trunc X), 0  <--> icmp ne (and X, C), 0
3616     // icmp sgt (trunc X), -1 <--> icmp eq (and X, C), 0
3617     unsigned DestSize = CmpLHS->getType()->getScalarSizeInBits();
3618     MinSignedValue = APInt::getSignedMinValue(DestSize).zext(BitWidth);
3619   } else {
3620     // icmp slt X, 0  <--> icmp ne (and X, C), 0
3621     // icmp sgt X, -1 <--> icmp eq (and X, C), 0
3622     X = CmpLHS;
3623     MinSignedValue = APInt::getSignedMinValue(BitWidth);
3624   }
3625 
3626   if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, &MinSignedValue,
3627                                        TrueWhenUnset))
3628     return V;
3629 
3630   return nullptr;
3631 }
3632 
3633 /// Try to simplify a select instruction when its condition operand is an
3634 /// integer comparison.
3635 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
3636                                          Value *FalseVal, const SimplifyQuery &Q,
3637                                          unsigned MaxRecurse) {
3638   ICmpInst::Predicate Pred;
3639   Value *CmpLHS, *CmpRHS;
3640   if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
3641     return nullptr;
3642 
3643   // FIXME: This code is nearly duplicated in InstCombine. Using/refactoring
3644   // decomposeBitTestICmp() might help.
3645   if (ICmpInst::isEquality(Pred) && match(CmpRHS, m_Zero())) {
3646     Value *X;
3647     const APInt *Y;
3648     if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y))))
3649       if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y,
3650                                            Pred == ICmpInst::ICMP_EQ))
3651         return V;
3652   } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
3653     // Comparing signed-less-than 0 checks if the sign bit is set.
3654     if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, TrueVal, FalseVal,
3655                                                 false))
3656       return V;
3657   } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
3658     // Comparing signed-greater-than -1 checks if the sign bit is not set.
3659     if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, TrueVal, FalseVal,
3660                                                 true))
3661       return V;
3662   }
3663 
3664   if (CondVal->hasOneUse()) {
3665     const APInt *C;
3666     if (match(CmpRHS, m_APInt(C))) {
3667       // X < MIN ? T : F  -->  F
3668       if (Pred == ICmpInst::ICMP_SLT && C->isMinSignedValue())
3669         return FalseVal;
3670       // X < MIN ? T : F  -->  F
3671       if (Pred == ICmpInst::ICMP_ULT && C->isMinValue())
3672         return FalseVal;
3673       // X > MAX ? T : F  -->  F
3674       if (Pred == ICmpInst::ICMP_SGT && C->isMaxSignedValue())
3675         return FalseVal;
3676       // X > MAX ? T : F  -->  F
3677       if (Pred == ICmpInst::ICMP_UGT && C->isMaxValue())
3678         return FalseVal;
3679     }
3680   }
3681 
3682   // If we have an equality comparison, then we know the value in one of the
3683   // arms of the select. See if substituting this value into the arm and
3684   // simplifying the result yields the same value as the other arm.
3685   if (Pred == ICmpInst::ICMP_EQ) {
3686     if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3687             TrueVal ||
3688         SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3689             TrueVal)
3690       return FalseVal;
3691     if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3692             FalseVal ||
3693         SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3694             FalseVal)
3695       return FalseVal;
3696   } else if (Pred == ICmpInst::ICMP_NE) {
3697     if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3698             FalseVal ||
3699         SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3700             FalseVal)
3701       return TrueVal;
3702     if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
3703             TrueVal ||
3704         SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
3705             TrueVal)
3706       return TrueVal;
3707   }
3708 
3709   return nullptr;
3710 }
3711 
3712 /// Given operands for a SelectInst, see if we can fold the result.
3713 /// If not, this returns null.
3714 static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
3715                                  Value *FalseVal, const SimplifyQuery &Q,
3716                                  unsigned MaxRecurse) {
3717   // select true, X, Y  -> X
3718   // select false, X, Y -> Y
3719   if (Constant *CB = dyn_cast<Constant>(CondVal)) {
3720     if (CB->isAllOnesValue())
3721       return TrueVal;
3722     if (CB->isNullValue())
3723       return FalseVal;
3724   }
3725 
3726   // select C, X, X -> X
3727   if (TrueVal == FalseVal)
3728     return TrueVal;
3729 
3730   if (isa<UndefValue>(CondVal)) {  // select undef, X, Y -> X or Y
3731     if (isa<Constant>(FalseVal))
3732       return FalseVal;
3733     return TrueVal;
3734   }
3735   if (isa<UndefValue>(TrueVal))   // select C, undef, X -> X
3736     return FalseVal;
3737   if (isa<UndefValue>(FalseVal))   // select C, X, undef -> X
3738     return TrueVal;
3739 
3740   if (Value *V =
3741           simplifySelectWithICmpCond(CondVal, TrueVal, FalseVal, Q, MaxRecurse))
3742     return V;
3743 
3744   return nullptr;
3745 }
3746 
3747 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
3748                                 const SimplifyQuery &Q) {
3749   return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit);
3750 }
3751 
3752 /// Given operands for an GetElementPtrInst, see if we can fold the result.
3753 /// If not, this returns null.
3754 static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
3755                               const SimplifyQuery &Q, unsigned) {
3756   // The type of the GEP pointer operand.
3757   unsigned AS =
3758       cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace();
3759 
3760   // getelementptr P -> P.
3761   if (Ops.size() == 1)
3762     return Ops[0];
3763 
3764   // Compute the (pointer) type returned by the GEP instruction.
3765   Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1));
3766   Type *GEPTy = PointerType::get(LastType, AS);
3767   if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
3768     GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3769   else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType()))
3770     GEPTy = VectorType::get(GEPTy, VT->getNumElements());
3771 
3772   if (isa<UndefValue>(Ops[0]))
3773     return UndefValue::get(GEPTy);
3774 
3775   if (Ops.size() == 2) {
3776     // getelementptr P, 0 -> P.
3777     if (match(Ops[1], m_Zero()))
3778       return Ops[0];
3779 
3780     Type *Ty = SrcTy;
3781     if (Ty->isSized()) {
3782       Value *P;
3783       uint64_t C;
3784       uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty);
3785       // getelementptr P, N -> P if P points to a type of zero size.
3786       if (TyAllocSize == 0)
3787         return Ops[0];
3788 
3789       // The following transforms are only safe if the ptrtoint cast
3790       // doesn't truncate the pointers.
3791       if (Ops[1]->getType()->getScalarSizeInBits() ==
3792           Q.DL.getPointerSizeInBits(AS)) {
3793         auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * {
3794           if (match(P, m_Zero()))
3795             return Constant::getNullValue(GEPTy);
3796           Value *Temp;
3797           if (match(P, m_PtrToInt(m_Value(Temp))))
3798             if (Temp->getType() == GEPTy)
3799               return Temp;
3800           return nullptr;
3801         };
3802 
3803         // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
3804         if (TyAllocSize == 1 &&
3805             match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0])))))
3806           if (Value *R = PtrToIntOrZero(P))
3807             return R;
3808 
3809         // getelementptr V, (ashr (sub P, V), C) -> Q
3810         // if P points to a type of size 1 << C.
3811         if (match(Ops[1],
3812                   m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3813                          m_ConstantInt(C))) &&
3814             TyAllocSize == 1ULL << C)
3815           if (Value *R = PtrToIntOrZero(P))
3816             return R;
3817 
3818         // getelementptr V, (sdiv (sub P, V), C) -> Q
3819         // if P points to a type of size C.
3820         if (match(Ops[1],
3821                   m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
3822                          m_SpecificInt(TyAllocSize))))
3823           if (Value *R = PtrToIntOrZero(P))
3824             return R;
3825       }
3826     }
3827   }
3828 
3829   if (Q.DL.getTypeAllocSize(LastType) == 1 &&
3830       all_of(Ops.slice(1).drop_back(1),
3831              [](Value *Idx) { return match(Idx, m_Zero()); })) {
3832     unsigned PtrWidth =
3833         Q.DL.getPointerSizeInBits(Ops[0]->getType()->getPointerAddressSpace());
3834     if (Q.DL.getTypeSizeInBits(Ops.back()->getType()) == PtrWidth) {
3835       APInt BasePtrOffset(PtrWidth, 0);
3836       Value *StrippedBasePtr =
3837           Ops[0]->stripAndAccumulateInBoundsConstantOffsets(Q.DL,
3838                                                             BasePtrOffset);
3839 
3840       // gep (gep V, C), (sub 0, V) -> C
3841       if (match(Ops.back(),
3842                 m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr))))) {
3843         auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset);
3844         return ConstantExpr::getIntToPtr(CI, GEPTy);
3845       }
3846       // gep (gep V, C), (xor V, -1) -> C-1
3847       if (match(Ops.back(),
3848                 m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes()))) {
3849         auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1);
3850         return ConstantExpr::getIntToPtr(CI, GEPTy);
3851       }
3852     }
3853   }
3854 
3855   // Check to see if this is constant foldable.
3856   for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3857     if (!isa<Constant>(Ops[i]))
3858       return nullptr;
3859 
3860   return ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]),
3861                                         Ops.slice(1));
3862 }
3863 
3864 Value *llvm::SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
3865                              const SimplifyQuery &Q) {
3866   return ::SimplifyGEPInst(SrcTy, Ops, Q, RecursionLimit);
3867 }
3868 
3869 /// Given operands for an InsertValueInst, see if we can fold the result.
3870 /// If not, this returns null.
3871 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
3872                                       ArrayRef<unsigned> Idxs, const SimplifyQuery &Q,
3873                                       unsigned) {
3874   if (Constant *CAgg = dyn_cast<Constant>(Agg))
3875     if (Constant *CVal = dyn_cast<Constant>(Val))
3876       return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
3877 
3878   // insertvalue x, undef, n -> x
3879   if (match(Val, m_Undef()))
3880     return Agg;
3881 
3882   // insertvalue x, (extractvalue y, n), n
3883   if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
3884     if (EV->getAggregateOperand()->getType() == Agg->getType() &&
3885         EV->getIndices() == Idxs) {
3886       // insertvalue undef, (extractvalue y, n), n -> y
3887       if (match(Agg, m_Undef()))
3888         return EV->getAggregateOperand();
3889 
3890       // insertvalue y, (extractvalue y, n), n -> y
3891       if (Agg == EV->getAggregateOperand())
3892         return Agg;
3893     }
3894 
3895   return nullptr;
3896 }
3897 
3898 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
3899                                      ArrayRef<unsigned> Idxs,
3900                                      const SimplifyQuery &Q) {
3901   return ::SimplifyInsertValueInst(Agg, Val, Idxs, Q, RecursionLimit);
3902 }
3903 
3904 /// Given operands for an ExtractValueInst, see if we can fold the result.
3905 /// If not, this returns null.
3906 static Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
3907                                        const SimplifyQuery &, unsigned) {
3908   if (auto *CAgg = dyn_cast<Constant>(Agg))
3909     return ConstantFoldExtractValueInstruction(CAgg, Idxs);
3910 
3911   // extractvalue x, (insertvalue y, elt, n), n -> elt
3912   unsigned NumIdxs = Idxs.size();
3913   for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr;
3914        IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) {
3915     ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices();
3916     unsigned NumInsertValueIdxs = InsertValueIdxs.size();
3917     unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs);
3918     if (InsertValueIdxs.slice(0, NumCommonIdxs) ==
3919         Idxs.slice(0, NumCommonIdxs)) {
3920       if (NumIdxs == NumInsertValueIdxs)
3921         return IVI->getInsertedValueOperand();
3922       break;
3923     }
3924   }
3925 
3926   return nullptr;
3927 }
3928 
3929 Value *llvm::SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
3930                                       const SimplifyQuery &Q) {
3931   return ::SimplifyExtractValueInst(Agg, Idxs, Q, RecursionLimit);
3932 }
3933 
3934 /// Given operands for an ExtractElementInst, see if we can fold the result.
3935 /// If not, this returns null.
3936 static Value *SimplifyExtractElementInst(Value *Vec, Value *Idx, const SimplifyQuery &,
3937                                          unsigned) {
3938   if (auto *CVec = dyn_cast<Constant>(Vec)) {
3939     if (auto *CIdx = dyn_cast<Constant>(Idx))
3940       return ConstantFoldExtractElementInstruction(CVec, CIdx);
3941 
3942     // The index is not relevant if our vector is a splat.
3943     if (auto *Splat = CVec->getSplatValue())
3944       return Splat;
3945 
3946     if (isa<UndefValue>(Vec))
3947       return UndefValue::get(Vec->getType()->getVectorElementType());
3948   }
3949 
3950   // If extracting a specified index from the vector, see if we can recursively
3951   // find a previously computed scalar that was inserted into the vector.
3952   if (auto *IdxC = dyn_cast<ConstantInt>(Idx))
3953     if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
3954       return Elt;
3955 
3956   return nullptr;
3957 }
3958 
3959 Value *llvm::SimplifyExtractElementInst(Value *Vec, Value *Idx,
3960                                         const SimplifyQuery &Q) {
3961   return ::SimplifyExtractElementInst(Vec, Idx, Q, RecursionLimit);
3962 }
3963 
3964 /// See if we can fold the given phi. If not, returns null.
3965 static Value *SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q) {
3966   // If all of the PHI's incoming values are the same then replace the PHI node
3967   // with the common value.
3968   Value *CommonValue = nullptr;
3969   bool HasUndefInput = false;
3970   for (Value *Incoming : PN->incoming_values()) {
3971     // If the incoming value is the phi node itself, it can safely be skipped.
3972     if (Incoming == PN) continue;
3973     if (isa<UndefValue>(Incoming)) {
3974       // Remember that we saw an undef value, but otherwise ignore them.
3975       HasUndefInput = true;
3976       continue;
3977     }
3978     if (CommonValue && Incoming != CommonValue)
3979       return nullptr;  // Not the same, bail out.
3980     CommonValue = Incoming;
3981   }
3982 
3983   // If CommonValue is null then all of the incoming values were either undef or
3984   // equal to the phi node itself.
3985   if (!CommonValue)
3986     return UndefValue::get(PN->getType());
3987 
3988   // If we have a PHI node like phi(X, undef, X), where X is defined by some
3989   // instruction, we cannot return X as the result of the PHI node unless it
3990   // dominates the PHI block.
3991   if (HasUndefInput)
3992     return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr;
3993 
3994   return CommonValue;
3995 }
3996 
3997 static Value *SimplifyCastInst(unsigned CastOpc, Value *Op,
3998                                Type *Ty, const SimplifyQuery &Q, unsigned MaxRecurse) {
3999   if (auto *C = dyn_cast<Constant>(Op))
4000     return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL);
4001 
4002   if (auto *CI = dyn_cast<CastInst>(Op)) {
4003     auto *Src = CI->getOperand(0);
4004     Type *SrcTy = Src->getType();
4005     Type *MidTy = CI->getType();
4006     Type *DstTy = Ty;
4007     if (Src->getType() == Ty) {
4008       auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode());
4009       auto SecondOp = static_cast<Instruction::CastOps>(CastOpc);
4010       Type *SrcIntPtrTy =
4011           SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr;
4012       Type *MidIntPtrTy =
4013           MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr;
4014       Type *DstIntPtrTy =
4015           DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr;
4016       if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy,
4017                                          SrcIntPtrTy, MidIntPtrTy,
4018                                          DstIntPtrTy) == Instruction::BitCast)
4019         return Src;
4020     }
4021   }
4022 
4023   // bitcast x -> x
4024   if (CastOpc == Instruction::BitCast)
4025     if (Op->getType() == Ty)
4026       return Op;
4027 
4028   return nullptr;
4029 }
4030 
4031 Value *llvm::SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
4032                               const SimplifyQuery &Q) {
4033   return ::SimplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit);
4034 }
4035 
4036 /// For the given destination element of a shuffle, peek through shuffles to
4037 /// match a root vector source operand that contains that element in the same
4038 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s).
4039 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1,
4040                                    int MaskVal, Value *RootVec,
4041                                    unsigned MaxRecurse) {
4042   if (!MaxRecurse--)
4043     return nullptr;
4044 
4045   // Bail out if any mask value is undefined. That kind of shuffle may be
4046   // simplified further based on demanded bits or other folds.
4047   if (MaskVal == -1)
4048     return nullptr;
4049 
4050   // The mask value chooses which source operand we need to look at next.
4051   int InVecNumElts = Op0->getType()->getVectorNumElements();
4052   int RootElt = MaskVal;
4053   Value *SourceOp = Op0;
4054   if (MaskVal >= InVecNumElts) {
4055     RootElt = MaskVal - InVecNumElts;
4056     SourceOp = Op1;
4057   }
4058 
4059   // If the source operand is a shuffle itself, look through it to find the
4060   // matching root vector.
4061   if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) {
4062     return foldIdentityShuffles(
4063         DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1),
4064         SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse);
4065   }
4066 
4067   // TODO: Look through bitcasts? What if the bitcast changes the vector element
4068   // size?
4069 
4070   // The source operand is not a shuffle. Initialize the root vector value for
4071   // this shuffle if that has not been done yet.
4072   if (!RootVec)
4073     RootVec = SourceOp;
4074 
4075   // Give up as soon as a source operand does not match the existing root value.
4076   if (RootVec != SourceOp)
4077     return nullptr;
4078 
4079   // The element must be coming from the same lane in the source vector
4080   // (although it may have crossed lanes in intermediate shuffles).
4081   if (RootElt != DestElt)
4082     return nullptr;
4083 
4084   return RootVec;
4085 }
4086 
4087 static Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *Mask,
4088                                         Type *RetTy, const SimplifyQuery &Q,
4089                                         unsigned MaxRecurse) {
4090   if (isa<UndefValue>(Mask))
4091     return UndefValue::get(RetTy);
4092 
4093   Type *InVecTy = Op0->getType();
4094   unsigned MaskNumElts = Mask->getType()->getVectorNumElements();
4095   unsigned InVecNumElts = InVecTy->getVectorNumElements();
4096 
4097   SmallVector<int, 32> Indices;
4098   ShuffleVectorInst::getShuffleMask(Mask, Indices);
4099   assert(MaskNumElts == Indices.size() &&
4100          "Size of Indices not same as number of mask elements?");
4101 
4102   // Canonicalization: If mask does not select elements from an input vector,
4103   // replace that input vector with undef.
4104   bool MaskSelects0 = false, MaskSelects1 = false;
4105   for (unsigned i = 0; i != MaskNumElts; ++i) {
4106     if (Indices[i] == -1)
4107       continue;
4108     if ((unsigned)Indices[i] < InVecNumElts)
4109       MaskSelects0 = true;
4110     else
4111       MaskSelects1 = true;
4112   }
4113   if (!MaskSelects0)
4114     Op0 = UndefValue::get(InVecTy);
4115   if (!MaskSelects1)
4116     Op1 = UndefValue::get(InVecTy);
4117 
4118   auto *Op0Const = dyn_cast<Constant>(Op0);
4119   auto *Op1Const = dyn_cast<Constant>(Op1);
4120 
4121   // If all operands are constant, constant fold the shuffle.
4122   if (Op0Const && Op1Const)
4123     return ConstantFoldShuffleVectorInstruction(Op0Const, Op1Const, Mask);
4124 
4125   // Canonicalization: if only one input vector is constant, it shall be the
4126   // second one.
4127   if (Op0Const && !Op1Const) {
4128     std::swap(Op0, Op1);
4129     ShuffleVectorInst::commuteShuffleMask(Indices, InVecNumElts);
4130   }
4131 
4132   // A shuffle of a splat is always the splat itself. Legal if the shuffle's
4133   // value type is same as the input vectors' type.
4134   if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0))
4135     if (isa<UndefValue>(Op1) && RetTy == InVecTy &&
4136         OpShuf->getMask()->getSplatValue())
4137       return Op0;
4138 
4139   // Don't fold a shuffle with undef mask elements. This may get folded in a
4140   // better way using demanded bits or other analysis.
4141   // TODO: Should we allow this?
4142   if (find(Indices, -1) != Indices.end())
4143     return nullptr;
4144 
4145   // Check if every element of this shuffle can be mapped back to the
4146   // corresponding element of a single root vector. If so, we don't need this
4147   // shuffle. This handles simple identity shuffles as well as chains of
4148   // shuffles that may widen/narrow and/or move elements across lanes and back.
4149   Value *RootVec = nullptr;
4150   for (unsigned i = 0; i != MaskNumElts; ++i) {
4151     // Note that recursion is limited for each vector element, so if any element
4152     // exceeds the limit, this will fail to simplify.
4153     RootVec =
4154         foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse);
4155 
4156     // We can't replace a widening/narrowing shuffle with one of its operands.
4157     if (!RootVec || RootVec->getType() != RetTy)
4158       return nullptr;
4159   }
4160   return RootVec;
4161 }
4162 
4163 /// Given operands for a ShuffleVectorInst, fold the result or return null.
4164 Value *llvm::SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *Mask,
4165                                        Type *RetTy, const SimplifyQuery &Q) {
4166   return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit);
4167 }
4168 
4169 //=== Helper functions for higher up the class hierarchy.
4170 
4171 /// Given operands for a BinaryOperator, see if we can fold the result.
4172 /// If not, this returns null.
4173 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4174                             const SimplifyQuery &Q, unsigned MaxRecurse) {
4175   switch (Opcode) {
4176   case Instruction::Add:
4177     return SimplifyAddInst(LHS, RHS, false, false, Q, MaxRecurse);
4178   case Instruction::FAdd:
4179     return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4180   case Instruction::Sub:
4181     return SimplifySubInst(LHS, RHS, false, false, Q, MaxRecurse);
4182   case Instruction::FSub:
4183     return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4184   case Instruction::Mul:
4185     return SimplifyMulInst(LHS, RHS, Q, MaxRecurse);
4186   case Instruction::FMul:
4187     return SimplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4188   case Instruction::SDiv:
4189     return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
4190   case Instruction::UDiv:
4191     return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
4192   case Instruction::FDiv:
4193     return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4194   case Instruction::SRem:
4195     return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
4196   case Instruction::URem:
4197     return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
4198   case Instruction::FRem:
4199     return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4200   case Instruction::Shl:
4201     return SimplifyShlInst(LHS, RHS, false, false, Q, MaxRecurse);
4202   case Instruction::LShr:
4203     return SimplifyLShrInst(LHS, RHS, false, Q, MaxRecurse);
4204   case Instruction::AShr:
4205     return SimplifyAShrInst(LHS, RHS, false, Q, MaxRecurse);
4206   case Instruction::And:
4207     return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
4208   case Instruction::Or:
4209     return SimplifyOrInst(LHS, RHS, Q, MaxRecurse);
4210   case Instruction::Xor:
4211     return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
4212   default:
4213     llvm_unreachable("Unexpected opcode");
4214   }
4215 }
4216 
4217 /// Given operands for a BinaryOperator, see if we can fold the result.
4218 /// If not, this returns null.
4219 /// In contrast to SimplifyBinOp, try to use FastMathFlag when folding the
4220 /// result. In case we don't need FastMathFlags, simply fall to SimplifyBinOp.
4221 static Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4222                               const FastMathFlags &FMF, const SimplifyQuery &Q,
4223                               unsigned MaxRecurse) {
4224   switch (Opcode) {
4225   case Instruction::FAdd:
4226     return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse);
4227   case Instruction::FSub:
4228     return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse);
4229   case Instruction::FMul:
4230     return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse);
4231   case Instruction::FDiv:
4232     return SimplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse);
4233   default:
4234     return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
4235   }
4236 }
4237 
4238 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4239                            const SimplifyQuery &Q) {
4240   return ::SimplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit);
4241 }
4242 
4243 Value *llvm::SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
4244                              FastMathFlags FMF, const SimplifyQuery &Q) {
4245   return ::SimplifyFPBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit);
4246 }
4247 
4248 /// Given operands for a CmpInst, see if we can fold the result.
4249 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
4250                               const SimplifyQuery &Q, unsigned MaxRecurse) {
4251   if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
4252     return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
4253   return SimplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse);
4254 }
4255 
4256 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
4257                              const SimplifyQuery &Q) {
4258   return ::SimplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
4259 }
4260 
4261 static bool IsIdempotent(Intrinsic::ID ID) {
4262   switch (ID) {
4263   default: return false;
4264 
4265   // Unary idempotent: f(f(x)) = f(x)
4266   case Intrinsic::fabs:
4267   case Intrinsic::floor:
4268   case Intrinsic::ceil:
4269   case Intrinsic::trunc:
4270   case Intrinsic::rint:
4271   case Intrinsic::nearbyint:
4272   case Intrinsic::round:
4273     return true;
4274   }
4275 }
4276 
4277 static Value *SimplifyRelativeLoad(Constant *Ptr, Constant *Offset,
4278                                    const DataLayout &DL) {
4279   GlobalValue *PtrSym;
4280   APInt PtrOffset;
4281   if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL))
4282     return nullptr;
4283 
4284   Type *Int8PtrTy = Type::getInt8PtrTy(Ptr->getContext());
4285   Type *Int32Ty = Type::getInt32Ty(Ptr->getContext());
4286   Type *Int32PtrTy = Int32Ty->getPointerTo();
4287   Type *Int64Ty = Type::getInt64Ty(Ptr->getContext());
4288 
4289   auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset);
4290   if (!OffsetConstInt || OffsetConstInt->getType()->getBitWidth() > 64)
4291     return nullptr;
4292 
4293   uint64_t OffsetInt = OffsetConstInt->getSExtValue();
4294   if (OffsetInt % 4 != 0)
4295     return nullptr;
4296 
4297   Constant *C = ConstantExpr::getGetElementPtr(
4298       Int32Ty, ConstantExpr::getBitCast(Ptr, Int32PtrTy),
4299       ConstantInt::get(Int64Ty, OffsetInt / 4));
4300   Constant *Loaded = ConstantFoldLoadFromConstPtr(C, Int32Ty, DL);
4301   if (!Loaded)
4302     return nullptr;
4303 
4304   auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded);
4305   if (!LoadedCE)
4306     return nullptr;
4307 
4308   if (LoadedCE->getOpcode() == Instruction::Trunc) {
4309     LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
4310     if (!LoadedCE)
4311       return nullptr;
4312   }
4313 
4314   if (LoadedCE->getOpcode() != Instruction::Sub)
4315     return nullptr;
4316 
4317   auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
4318   if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt)
4319     return nullptr;
4320   auto *LoadedLHSPtr = LoadedLHS->getOperand(0);
4321 
4322   Constant *LoadedRHS = LoadedCE->getOperand(1);
4323   GlobalValue *LoadedRHSSym;
4324   APInt LoadedRHSOffset;
4325   if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset,
4326                                   DL) ||
4327       PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset)
4328     return nullptr;
4329 
4330   return ConstantExpr::getBitCast(LoadedLHSPtr, Int8PtrTy);
4331 }
4332 
4333 static bool maskIsAllZeroOrUndef(Value *Mask) {
4334   auto *ConstMask = dyn_cast<Constant>(Mask);
4335   if (!ConstMask)
4336     return false;
4337   if (ConstMask->isNullValue() || isa<UndefValue>(ConstMask))
4338     return true;
4339   for (unsigned I = 0, E = ConstMask->getType()->getVectorNumElements(); I != E;
4340        ++I) {
4341     if (auto *MaskElt = ConstMask->getAggregateElement(I))
4342       if (MaskElt->isNullValue() || isa<UndefValue>(MaskElt))
4343         continue;
4344     return false;
4345   }
4346   return true;
4347 }
4348 
4349 template <typename IterTy>
4350 static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
4351                                 const SimplifyQuery &Q, unsigned MaxRecurse) {
4352   Intrinsic::ID IID = F->getIntrinsicID();
4353   unsigned NumOperands = std::distance(ArgBegin, ArgEnd);
4354 
4355   // Unary Ops
4356   if (NumOperands == 1) {
4357     // Perform idempotent optimizations
4358     if (IsIdempotent(IID)) {
4359       if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin)) {
4360         if (II->getIntrinsicID() == IID)
4361           return II;
4362       }
4363     }
4364 
4365     switch (IID) {
4366     case Intrinsic::fabs: {
4367       if (SignBitMustBeZero(*ArgBegin, Q.TLI))
4368         return *ArgBegin;
4369       return nullptr;
4370     }
4371     default:
4372       return nullptr;
4373     }
4374   }
4375 
4376   // Binary Ops
4377   if (NumOperands == 2) {
4378     Value *LHS = *ArgBegin;
4379     Value *RHS = *(ArgBegin + 1);
4380     Type *ReturnType = F->getReturnType();
4381 
4382     switch (IID) {
4383     case Intrinsic::usub_with_overflow:
4384     case Intrinsic::ssub_with_overflow: {
4385       // X - X -> { 0, false }
4386       if (LHS == RHS)
4387         return Constant::getNullValue(ReturnType);
4388 
4389       // X - undef -> undef
4390       // undef - X -> undef
4391       if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS))
4392         return UndefValue::get(ReturnType);
4393 
4394       return nullptr;
4395     }
4396     case Intrinsic::uadd_with_overflow:
4397     case Intrinsic::sadd_with_overflow: {
4398       // X + undef -> undef
4399       if (isa<UndefValue>(RHS))
4400         return UndefValue::get(ReturnType);
4401 
4402       return nullptr;
4403     }
4404     case Intrinsic::umul_with_overflow:
4405     case Intrinsic::smul_with_overflow: {
4406       // X * 0 -> { 0, false }
4407       if (match(RHS, m_Zero()))
4408         return Constant::getNullValue(ReturnType);
4409 
4410       // X * undef -> { 0, false }
4411       if (match(RHS, m_Undef()))
4412         return Constant::getNullValue(ReturnType);
4413 
4414       return nullptr;
4415     }
4416     case Intrinsic::load_relative: {
4417       Constant *C0 = dyn_cast<Constant>(LHS);
4418       Constant *C1 = dyn_cast<Constant>(RHS);
4419       if (C0 && C1)
4420         return SimplifyRelativeLoad(C0, C1, Q.DL);
4421       return nullptr;
4422     }
4423     default:
4424       return nullptr;
4425     }
4426   }
4427 
4428   // Simplify calls to llvm.masked.load.*
4429   switch (IID) {
4430   case Intrinsic::masked_load: {
4431     Value *MaskArg = ArgBegin[2];
4432     Value *PassthruArg = ArgBegin[3];
4433     // If the mask is all zeros or undef, the "passthru" argument is the result.
4434     if (maskIsAllZeroOrUndef(MaskArg))
4435       return PassthruArg;
4436     return nullptr;
4437   }
4438   default:
4439     return nullptr;
4440   }
4441 }
4442 
4443 template <typename IterTy>
4444 static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd,
4445                            const SimplifyQuery &Q, unsigned MaxRecurse) {
4446   Type *Ty = V->getType();
4447   if (PointerType *PTy = dyn_cast<PointerType>(Ty))
4448     Ty = PTy->getElementType();
4449   FunctionType *FTy = cast<FunctionType>(Ty);
4450 
4451   // call undef -> undef
4452   // call null -> undef
4453   if (isa<UndefValue>(V) || isa<ConstantPointerNull>(V))
4454     return UndefValue::get(FTy->getReturnType());
4455 
4456   Function *F = dyn_cast<Function>(V);
4457   if (!F)
4458     return nullptr;
4459 
4460   if (F->isIntrinsic())
4461     if (Value *Ret = SimplifyIntrinsic(F, ArgBegin, ArgEnd, Q, MaxRecurse))
4462       return Ret;
4463 
4464   if (!canConstantFoldCallTo(F))
4465     return nullptr;
4466 
4467   SmallVector<Constant *, 4> ConstantArgs;
4468   ConstantArgs.reserve(ArgEnd - ArgBegin);
4469   for (IterTy I = ArgBegin, E = ArgEnd; I != E; ++I) {
4470     Constant *C = dyn_cast<Constant>(*I);
4471     if (!C)
4472       return nullptr;
4473     ConstantArgs.push_back(C);
4474   }
4475 
4476   return ConstantFoldCall(F, ConstantArgs, Q.TLI);
4477 }
4478 
4479 Value *llvm::SimplifyCall(Value *V, User::op_iterator ArgBegin,
4480                           User::op_iterator ArgEnd, const SimplifyQuery &Q) {
4481   return ::SimplifyCall(V, ArgBegin, ArgEnd, Q, RecursionLimit);
4482 }
4483 
4484 Value *llvm::SimplifyCall(Value *V, ArrayRef<Value *> Args,
4485                           const SimplifyQuery &Q) {
4486   return ::SimplifyCall(V, Args.begin(), Args.end(), Q, RecursionLimit);
4487 }
4488 
4489 /// See if we can compute a simplified version of this instruction.
4490 /// If not, this returns null.
4491 
4492 Value *llvm::SimplifyInstruction(Instruction *I, const SimplifyQuery &SQ,
4493                                  OptimizationRemarkEmitter *ORE) {
4494   const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I);
4495   Value *Result;
4496 
4497   switch (I->getOpcode()) {
4498   default:
4499     Result = ConstantFoldInstruction(I, Q.DL, Q.TLI);
4500     break;
4501   case Instruction::FAdd:
4502     Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
4503                               I->getFastMathFlags(), Q);
4504     break;
4505   case Instruction::Add:
4506     Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
4507                              cast<BinaryOperator>(I)->hasNoSignedWrap(),
4508                              cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4509     break;
4510   case Instruction::FSub:
4511     Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
4512                               I->getFastMathFlags(), Q);
4513     break;
4514   case Instruction::Sub:
4515     Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
4516                              cast<BinaryOperator>(I)->hasNoSignedWrap(),
4517                              cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4518     break;
4519   case Instruction::FMul:
4520     Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1),
4521                               I->getFastMathFlags(), Q);
4522     break;
4523   case Instruction::Mul:
4524     Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), Q);
4525     break;
4526   case Instruction::SDiv:
4527     Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), Q);
4528     break;
4529   case Instruction::UDiv:
4530     Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), Q);
4531     break;
4532   case Instruction::FDiv:
4533     Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1),
4534                               I->getFastMathFlags(), Q);
4535     break;
4536   case Instruction::SRem:
4537     Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), Q);
4538     break;
4539   case Instruction::URem:
4540     Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), Q);
4541     break;
4542   case Instruction::FRem:
4543     Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1),
4544                               I->getFastMathFlags(), Q);
4545     break;
4546   case Instruction::Shl:
4547     Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
4548                              cast<BinaryOperator>(I)->hasNoSignedWrap(),
4549                              cast<BinaryOperator>(I)->hasNoUnsignedWrap(), Q);
4550     break;
4551   case Instruction::LShr:
4552     Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
4553                               cast<BinaryOperator>(I)->isExact(), Q);
4554     break;
4555   case Instruction::AShr:
4556     Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
4557                               cast<BinaryOperator>(I)->isExact(), Q);
4558     break;
4559   case Instruction::And:
4560     Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), Q);
4561     break;
4562   case Instruction::Or:
4563     Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), Q);
4564     break;
4565   case Instruction::Xor:
4566     Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), Q);
4567     break;
4568   case Instruction::ICmp:
4569     Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
4570                               I->getOperand(0), I->getOperand(1), Q);
4571     break;
4572   case Instruction::FCmp:
4573     Result =
4574         SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0),
4575                          I->getOperand(1), I->getFastMathFlags(), Q);
4576     break;
4577   case Instruction::Select:
4578     Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
4579                                 I->getOperand(2), Q);
4580     break;
4581   case Instruction::GetElementPtr: {
4582     SmallVector<Value *, 8> Ops(I->op_begin(), I->op_end());
4583     Result = SimplifyGEPInst(cast<GetElementPtrInst>(I)->getSourceElementType(),
4584                              Ops, Q);
4585     break;
4586   }
4587   case Instruction::InsertValue: {
4588     InsertValueInst *IV = cast<InsertValueInst>(I);
4589     Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
4590                                      IV->getInsertedValueOperand(),
4591                                      IV->getIndices(), Q);
4592     break;
4593   }
4594   case Instruction::ExtractValue: {
4595     auto *EVI = cast<ExtractValueInst>(I);
4596     Result = SimplifyExtractValueInst(EVI->getAggregateOperand(),
4597                                       EVI->getIndices(), Q);
4598     break;
4599   }
4600   case Instruction::ExtractElement: {
4601     auto *EEI = cast<ExtractElementInst>(I);
4602     Result = SimplifyExtractElementInst(EEI->getVectorOperand(),
4603                                         EEI->getIndexOperand(), Q);
4604     break;
4605   }
4606   case Instruction::ShuffleVector: {
4607     auto *SVI = cast<ShuffleVectorInst>(I);
4608     Result = SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
4609                                        SVI->getMask(), SVI->getType(), Q);
4610     break;
4611   }
4612   case Instruction::PHI:
4613     Result = SimplifyPHINode(cast<PHINode>(I), Q);
4614     break;
4615   case Instruction::Call: {
4616     CallSite CS(cast<CallInst>(I));
4617     Result = SimplifyCall(CS.getCalledValue(), CS.arg_begin(), CS.arg_end(), Q);
4618     break;
4619   }
4620 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc:
4621 #include "llvm/IR/Instruction.def"
4622 #undef HANDLE_CAST_INST
4623     Result =
4624         SimplifyCastInst(I->getOpcode(), I->getOperand(0), I->getType(), Q);
4625     break;
4626   case Instruction::Alloca:
4627     // No simplifications for Alloca and it can't be constant folded.
4628     Result = nullptr;
4629     break;
4630   }
4631 
4632   // In general, it is possible for computeKnownBits to determine all bits in a
4633   // value even when the operands are not all constants.
4634   if (!Result && I->getType()->isIntOrIntVectorTy()) {
4635     unsigned BitWidth = I->getType()->getScalarSizeInBits();
4636     KnownBits Known(BitWidth);
4637     computeKnownBits(I, Known, Q.DL, /*Depth*/ 0, Q.AC, I, Q.DT, ORE);
4638     if (Known.isConstant())
4639       Result = ConstantInt::get(I->getType(), Known.getConstant());
4640   }
4641 
4642   /// If called on unreachable code, the above logic may report that the
4643   /// instruction simplified to itself.  Make life easier for users by
4644   /// detecting that case here, returning a safe value instead.
4645   return Result == I ? UndefValue::get(I->getType()) : Result;
4646 }
4647 
4648 /// \brief Implementation of recursive simplification through an instruction's
4649 /// uses.
4650 ///
4651 /// This is the common implementation of the recursive simplification routines.
4652 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
4653 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
4654 /// instructions to process and attempt to simplify it using
4655 /// InstructionSimplify.
4656 ///
4657 /// This routine returns 'true' only when *it* simplifies something. The passed
4658 /// in simplified value does not count toward this.
4659 static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
4660                                               const TargetLibraryInfo *TLI,
4661                                               const DominatorTree *DT,
4662                                               AssumptionCache *AC) {
4663   bool Simplified = false;
4664   SmallSetVector<Instruction *, 8> Worklist;
4665   const DataLayout &DL = I->getModule()->getDataLayout();
4666 
4667   // If we have an explicit value to collapse to, do that round of the
4668   // simplification loop by hand initially.
4669   if (SimpleV) {
4670     for (User *U : I->users())
4671       if (U != I)
4672         Worklist.insert(cast<Instruction>(U));
4673 
4674     // Replace the instruction with its simplified value.
4675     I->replaceAllUsesWith(SimpleV);
4676 
4677     // Gracefully handle edge cases where the instruction is not wired into any
4678     // parent block.
4679     if (I->getParent() && !I->isEHPad() && !isa<TerminatorInst>(I) &&
4680         !I->mayHaveSideEffects())
4681       I->eraseFromParent();
4682   } else {
4683     Worklist.insert(I);
4684   }
4685 
4686   // Note that we must test the size on each iteration, the worklist can grow.
4687   for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
4688     I = Worklist[Idx];
4689 
4690     // See if this instruction simplifies.
4691     SimpleV = SimplifyInstruction(I, {DL, TLI, DT, AC});
4692     if (!SimpleV)
4693       continue;
4694 
4695     Simplified = true;
4696 
4697     // Stash away all the uses of the old instruction so we can check them for
4698     // recursive simplifications after a RAUW. This is cheaper than checking all
4699     // uses of To on the recursive step in most cases.
4700     for (User *U : I->users())
4701       Worklist.insert(cast<Instruction>(U));
4702 
4703     // Replace the instruction with its simplified value.
4704     I->replaceAllUsesWith(SimpleV);
4705 
4706     // Gracefully handle edge cases where the instruction is not wired into any
4707     // parent block.
4708     if (I->getParent() && !I->isEHPad() && !isa<TerminatorInst>(I) &&
4709         !I->mayHaveSideEffects())
4710       I->eraseFromParent();
4711   }
4712   return Simplified;
4713 }
4714 
4715 bool llvm::recursivelySimplifyInstruction(Instruction *I,
4716                                           const TargetLibraryInfo *TLI,
4717                                           const DominatorTree *DT,
4718                                           AssumptionCache *AC) {
4719   return replaceAndRecursivelySimplifyImpl(I, nullptr, TLI, DT, AC);
4720 }
4721 
4722 bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
4723                                          const TargetLibraryInfo *TLI,
4724                                          const DominatorTree *DT,
4725                                          AssumptionCache *AC) {
4726   assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
4727   assert(SimpleV && "Must provide a simplified value.");
4728   return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC);
4729 }
4730 
4731 namespace llvm {
4732 const SimplifyQuery getBestSimplifyQuery(Pass &P, Function &F) {
4733   auto *DTWP = P.getAnalysisIfAvailable<DominatorTreeWrapperPass>();
4734   auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
4735   auto *TLIWP = P.getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
4736   auto *TLI = TLIWP ? &TLIWP->getTLI() : nullptr;
4737   auto *ACWP = P.getAnalysisIfAvailable<AssumptionCacheTracker>();
4738   auto *AC = ACWP ? &ACWP->getAssumptionCache(F) : nullptr;
4739   return {F.getParent()->getDataLayout(), TLI, DT, AC};
4740 }
4741 
4742 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &AR,
4743                                          const DataLayout &DL) {
4744   return {DL, &AR.TLI, &AR.DT, &AR.AC};
4745 }
4746 
4747 template <class T, class... TArgs>
4748 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &AM,
4749                                          Function &F) {
4750   auto *DT = AM.template getCachedResult<DominatorTreeAnalysis>(F);
4751   auto *TLI = AM.template getCachedResult<TargetLibraryAnalysis>(F);
4752   auto *AC = AM.template getCachedResult<AssumptionAnalysis>(F);
4753   return {F.getParent()->getDataLayout(), TLI, DT, AC};
4754 }
4755 template const SimplifyQuery getBestSimplifyQuery(AnalysisManager<Function> &,
4756                                                   Function &);
4757 }
4758