xref: /freebsd/contrib/llvm-project/llvm/lib/Analysis/InstructionSimplify.cpp (revision 700637cbb5e582861067a11aaca4d053546871d2)
1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements routines for folding instructions into simpler forms
10 // that do not require creating new instructions.  This does constant folding
11 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
12 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
13 // ("and i32 %x, %x" -> "%x").  All operands are assumed to have already been
14 // simplified: This is usually true and assuming it simplifies the logic (if
15 // they have not been simplified then results are correct but maybe suboptimal).
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #include "llvm/Analysis/InstructionSimplify.h"
20 
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/ADT/SetVector.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/Analysis/AliasAnalysis.h"
25 #include "llvm/Analysis/AssumptionCache.h"
26 #include "llvm/Analysis/CaptureTracking.h"
27 #include "llvm/Analysis/CmpInstAnalysis.h"
28 #include "llvm/Analysis/ConstantFolding.h"
29 #include "llvm/Analysis/FloatingPointPredicateUtils.h"
30 #include "llvm/Analysis/InstSimplifyFolder.h"
31 #include "llvm/Analysis/Loads.h"
32 #include "llvm/Analysis/LoopAnalysisManager.h"
33 #include "llvm/Analysis/MemoryBuiltins.h"
34 #include "llvm/Analysis/OverflowInstAnalysis.h"
35 #include "llvm/Analysis/TargetLibraryInfo.h"
36 #include "llvm/Analysis/ValueTracking.h"
37 #include "llvm/Analysis/VectorUtils.h"
38 #include "llvm/IR/ConstantRange.h"
39 #include "llvm/IR/DataLayout.h"
40 #include "llvm/IR/Dominators.h"
41 #include "llvm/IR/InstrTypes.h"
42 #include "llvm/IR/Instructions.h"
43 #include "llvm/IR/Operator.h"
44 #include "llvm/IR/PatternMatch.h"
45 #include "llvm/IR/Statepoint.h"
46 #include "llvm/Support/KnownBits.h"
47 #include "llvm/Support/KnownFPClass.h"
48 #include <algorithm>
49 #include <optional>
50 using namespace llvm;
51 using namespace llvm::PatternMatch;
52 
53 #define DEBUG_TYPE "instsimplify"
54 
55 enum { RecursionLimit = 3 };
56 
57 STATISTIC(NumExpand, "Number of expansions");
58 STATISTIC(NumReassoc, "Number of reassociations");
59 
60 static Value *simplifyAndInst(Value *, Value *, const SimplifyQuery &,
61                               unsigned);
62 static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned);
63 static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &,
64                              const SimplifyQuery &, unsigned);
65 static Value *simplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &,
66                             unsigned);
67 static Value *simplifyBinOp(unsigned, Value *, Value *, const FastMathFlags &,
68                             const SimplifyQuery &, unsigned);
69 static Value *simplifyCmpInst(CmpPredicate, Value *, Value *,
70                               const SimplifyQuery &, unsigned);
71 static Value *simplifyICmpInst(CmpPredicate Predicate, Value *LHS, Value *RHS,
72                                const SimplifyQuery &Q, unsigned MaxRecurse);
73 static Value *simplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned);
74 static Value *simplifyXorInst(Value *, Value *, const SimplifyQuery &,
75                               unsigned);
76 static Value *simplifyCastInst(unsigned, Value *, Type *, const SimplifyQuery &,
77                                unsigned);
78 static Value *simplifyGEPInst(Type *, Value *, ArrayRef<Value *>,
79                               GEPNoWrapFlags, const SimplifyQuery &, unsigned);
80 static Value *simplifySelectInst(Value *, Value *, Value *,
81                                  const SimplifyQuery &, unsigned);
82 static Value *simplifyInstructionWithOperands(Instruction *I,
83                                               ArrayRef<Value *> NewOps,
84                                               const SimplifyQuery &SQ,
85                                               unsigned MaxRecurse);
86 
87 /// For a boolean type or a vector of boolean type, return false or a vector
88 /// with every element false.
getFalse(Type * Ty)89 static Constant *getFalse(Type *Ty) { return ConstantInt::getFalse(Ty); }
90 
91 /// For a boolean type or a vector of boolean type, return true or a vector
92 /// with every element true.
getTrue(Type * Ty)93 static Constant *getTrue(Type *Ty) { return ConstantInt::getTrue(Ty); }
94 
95 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
isSameCompare(Value * V,CmpPredicate Pred,Value * LHS,Value * RHS)96 static bool isSameCompare(Value *V, CmpPredicate Pred, Value *LHS, Value *RHS) {
97   CmpInst *Cmp = dyn_cast<CmpInst>(V);
98   if (!Cmp)
99     return false;
100   CmpInst::Predicate CPred = Cmp->getPredicate();
101   Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
102   if (CPred == Pred && CLHS == LHS && CRHS == RHS)
103     return true;
104   return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
105          CRHS == LHS;
106 }
107 
108 /// Simplify comparison with true or false branch of select:
109 ///  %sel = select i1 %cond, i32 %tv, i32 %fv
110 ///  %cmp = icmp sle i32 %sel, %rhs
111 /// Compose new comparison by substituting %sel with either %tv or %fv
112 /// and see if it simplifies.
simplifyCmpSelCase(CmpPredicate Pred,Value * LHS,Value * RHS,Value * Cond,const SimplifyQuery & Q,unsigned MaxRecurse,Constant * TrueOrFalse)113 static Value *simplifyCmpSelCase(CmpPredicate Pred, Value *LHS, Value *RHS,
114                                  Value *Cond, const SimplifyQuery &Q,
115                                  unsigned MaxRecurse, Constant *TrueOrFalse) {
116   Value *SimplifiedCmp = simplifyCmpInst(Pred, LHS, RHS, Q, MaxRecurse);
117   if (SimplifiedCmp == Cond) {
118     // %cmp simplified to the select condition (%cond).
119     return TrueOrFalse;
120   } else if (!SimplifiedCmp && isSameCompare(Cond, Pred, LHS, RHS)) {
121     // It didn't simplify. However, if composed comparison is equivalent
122     // to the select condition (%cond) then we can replace it.
123     return TrueOrFalse;
124   }
125   return SimplifiedCmp;
126 }
127 
128 /// Simplify comparison with true branch of select
simplifyCmpSelTrueCase(CmpPredicate Pred,Value * LHS,Value * RHS,Value * Cond,const SimplifyQuery & Q,unsigned MaxRecurse)129 static Value *simplifyCmpSelTrueCase(CmpPredicate Pred, Value *LHS, Value *RHS,
130                                      Value *Cond, const SimplifyQuery &Q,
131                                      unsigned MaxRecurse) {
132   return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse,
133                             getTrue(Cond->getType()));
134 }
135 
136 /// Simplify comparison with false branch of select
simplifyCmpSelFalseCase(CmpPredicate Pred,Value * LHS,Value * RHS,Value * Cond,const SimplifyQuery & Q,unsigned MaxRecurse)137 static Value *simplifyCmpSelFalseCase(CmpPredicate Pred, Value *LHS, Value *RHS,
138                                       Value *Cond, const SimplifyQuery &Q,
139                                       unsigned MaxRecurse) {
140   return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse,
141                             getFalse(Cond->getType()));
142 }
143 
144 /// We know comparison with both branches of select can be simplified, but they
145 /// are not equal. This routine handles some logical simplifications.
handleOtherCmpSelSimplifications(Value * TCmp,Value * FCmp,Value * Cond,const SimplifyQuery & Q,unsigned MaxRecurse)146 static Value *handleOtherCmpSelSimplifications(Value *TCmp, Value *FCmp,
147                                                Value *Cond,
148                                                const SimplifyQuery &Q,
149                                                unsigned MaxRecurse) {
150   // If the false value simplified to false, then the result of the compare
151   // is equal to "Cond && TCmp".  This also catches the case when the false
152   // value simplified to false and the true value to true, returning "Cond".
153   // Folding select to and/or isn't poison-safe in general; impliesPoison
154   // checks whether folding it does not convert a well-defined value into
155   // poison.
156   if (match(FCmp, m_Zero()) && impliesPoison(TCmp, Cond))
157     if (Value *V = simplifyAndInst(Cond, TCmp, Q, MaxRecurse))
158       return V;
159   // If the true value simplified to true, then the result of the compare
160   // is equal to "Cond || FCmp".
161   if (match(TCmp, m_One()) && impliesPoison(FCmp, Cond))
162     if (Value *V = simplifyOrInst(Cond, FCmp, Q, MaxRecurse))
163       return V;
164   // Finally, if the false value simplified to true and the true value to
165   // false, then the result of the compare is equal to "!Cond".
166   if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
167     if (Value *V = simplifyXorInst(
168             Cond, Constant::getAllOnesValue(Cond->getType()), Q, MaxRecurse))
169       return V;
170   return nullptr;
171 }
172 
173 /// Does the given value dominate the specified phi node?
valueDominatesPHI(Value * V,PHINode * P,const DominatorTree * DT)174 static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
175   Instruction *I = dyn_cast<Instruction>(V);
176   if (!I)
177     // Arguments and constants dominate all instructions.
178     return true;
179 
180   // If we have a DominatorTree then do a precise test.
181   if (DT)
182     return DT->dominates(I, P);
183 
184   // Otherwise, if the instruction is in the entry block and is not an invoke,
185   // then it obviously dominates all phi nodes.
186   if (I->getParent()->isEntryBlock() && !isa<InvokeInst>(I) &&
187       !isa<CallBrInst>(I))
188     return true;
189 
190   return false;
191 }
192 
193 /// Try to simplify a binary operator of form "V op OtherOp" where V is
194 /// "(B0 opex B1)" by distributing 'op' across 'opex' as
195 /// "(B0 op OtherOp) opex (B1 op OtherOp)".
expandBinOp(Instruction::BinaryOps Opcode,Value * V,Value * OtherOp,Instruction::BinaryOps OpcodeToExpand,const SimplifyQuery & Q,unsigned MaxRecurse)196 static Value *expandBinOp(Instruction::BinaryOps Opcode, Value *V,
197                           Value *OtherOp, Instruction::BinaryOps OpcodeToExpand,
198                           const SimplifyQuery &Q, unsigned MaxRecurse) {
199   auto *B = dyn_cast<BinaryOperator>(V);
200   if (!B || B->getOpcode() != OpcodeToExpand)
201     return nullptr;
202   Value *B0 = B->getOperand(0), *B1 = B->getOperand(1);
203   Value *L =
204       simplifyBinOp(Opcode, B0, OtherOp, Q.getWithoutUndef(), MaxRecurse);
205   if (!L)
206     return nullptr;
207   Value *R =
208       simplifyBinOp(Opcode, B1, OtherOp, Q.getWithoutUndef(), MaxRecurse);
209   if (!R)
210     return nullptr;
211 
212   // Does the expanded pair of binops simplify to the existing binop?
213   if ((L == B0 && R == B1) ||
214       (Instruction::isCommutative(OpcodeToExpand) && L == B1 && R == B0)) {
215     ++NumExpand;
216     return B;
217   }
218 
219   // Otherwise, return "L op' R" if it simplifies.
220   Value *S = simplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse);
221   if (!S)
222     return nullptr;
223 
224   ++NumExpand;
225   return S;
226 }
227 
228 /// Try to simplify binops of form "A op (B op' C)" or the commuted variant by
229 /// distributing op over op'.
expandCommutativeBinOp(Instruction::BinaryOps Opcode,Value * L,Value * R,Instruction::BinaryOps OpcodeToExpand,const SimplifyQuery & Q,unsigned MaxRecurse)230 static Value *expandCommutativeBinOp(Instruction::BinaryOps Opcode, Value *L,
231                                      Value *R,
232                                      Instruction::BinaryOps OpcodeToExpand,
233                                      const SimplifyQuery &Q,
234                                      unsigned MaxRecurse) {
235   // Recursion is always used, so bail out at once if we already hit the limit.
236   if (!MaxRecurse--)
237     return nullptr;
238 
239   if (Value *V = expandBinOp(Opcode, L, R, OpcodeToExpand, Q, MaxRecurse))
240     return V;
241   if (Value *V = expandBinOp(Opcode, R, L, OpcodeToExpand, Q, MaxRecurse))
242     return V;
243   return nullptr;
244 }
245 
246 /// Generic simplifications for associative binary operations.
247 /// Returns the simpler value, or null if none was found.
simplifyAssociativeBinOp(Instruction::BinaryOps Opcode,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)248 static Value *simplifyAssociativeBinOp(Instruction::BinaryOps Opcode,
249                                        Value *LHS, Value *RHS,
250                                        const SimplifyQuery &Q,
251                                        unsigned MaxRecurse) {
252   assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
253 
254   // Recursion is always used, so bail out at once if we already hit the limit.
255   if (!MaxRecurse--)
256     return nullptr;
257 
258   BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
259   BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
260 
261   // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
262   if (Op0 && Op0->getOpcode() == Opcode) {
263     Value *A = Op0->getOperand(0);
264     Value *B = Op0->getOperand(1);
265     Value *C = RHS;
266 
267     // Does "B op C" simplify?
268     if (Value *V = simplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
269       // It does!  Return "A op V" if it simplifies or is already available.
270       // If V equals B then "A op V" is just the LHS.
271       if (V == B)
272         return LHS;
273       // Otherwise return "A op V" if it simplifies.
274       if (Value *W = simplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
275         ++NumReassoc;
276         return W;
277       }
278     }
279   }
280 
281   // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
282   if (Op1 && Op1->getOpcode() == Opcode) {
283     Value *A = LHS;
284     Value *B = Op1->getOperand(0);
285     Value *C = Op1->getOperand(1);
286 
287     // Does "A op B" simplify?
288     if (Value *V = simplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
289       // It does!  Return "V op C" if it simplifies or is already available.
290       // If V equals B then "V op C" is just the RHS.
291       if (V == B)
292         return RHS;
293       // Otherwise return "V op C" if it simplifies.
294       if (Value *W = simplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
295         ++NumReassoc;
296         return W;
297       }
298     }
299   }
300 
301   // The remaining transforms require commutativity as well as associativity.
302   if (!Instruction::isCommutative(Opcode))
303     return nullptr;
304 
305   // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
306   if (Op0 && Op0->getOpcode() == Opcode) {
307     Value *A = Op0->getOperand(0);
308     Value *B = Op0->getOperand(1);
309     Value *C = RHS;
310 
311     // Does "C op A" simplify?
312     if (Value *V = simplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
313       // It does!  Return "V op B" if it simplifies or is already available.
314       // If V equals A then "V op B" is just the LHS.
315       if (V == A)
316         return LHS;
317       // Otherwise return "V op B" if it simplifies.
318       if (Value *W = simplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
319         ++NumReassoc;
320         return W;
321       }
322     }
323   }
324 
325   // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
326   if (Op1 && Op1->getOpcode() == Opcode) {
327     Value *A = LHS;
328     Value *B = Op1->getOperand(0);
329     Value *C = Op1->getOperand(1);
330 
331     // Does "C op A" simplify?
332     if (Value *V = simplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
333       // It does!  Return "B op V" if it simplifies or is already available.
334       // If V equals C then "B op V" is just the RHS.
335       if (V == C)
336         return RHS;
337       // Otherwise return "B op V" if it simplifies.
338       if (Value *W = simplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
339         ++NumReassoc;
340         return W;
341       }
342     }
343   }
344 
345   return nullptr;
346 }
347 
348 /// In the case of a binary operation with a select instruction as an operand,
349 /// try to simplify the binop by seeing whether evaluating it on both branches
350 /// of the select results in the same value. Returns the common value if so,
351 /// otherwise returns null.
threadBinOpOverSelect(Instruction::BinaryOps Opcode,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)352 static Value *threadBinOpOverSelect(Instruction::BinaryOps Opcode, Value *LHS,
353                                     Value *RHS, const SimplifyQuery &Q,
354                                     unsigned MaxRecurse) {
355   // Recursion is always used, so bail out at once if we already hit the limit.
356   if (!MaxRecurse--)
357     return nullptr;
358 
359   SelectInst *SI;
360   if (isa<SelectInst>(LHS)) {
361     SI = cast<SelectInst>(LHS);
362   } else {
363     assert(isa<SelectInst>(RHS) && "No select instruction operand!");
364     SI = cast<SelectInst>(RHS);
365   }
366 
367   // Evaluate the BinOp on the true and false branches of the select.
368   Value *TV;
369   Value *FV;
370   if (SI == LHS) {
371     TV = simplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
372     FV = simplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
373   } else {
374     TV = simplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
375     FV = simplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
376   }
377 
378   // If they simplified to the same value, then return the common value.
379   // If they both failed to simplify then return null.
380   if (TV == FV)
381     return TV;
382 
383   // If one branch simplified to undef, return the other one.
384   if (TV && Q.isUndefValue(TV))
385     return FV;
386   if (FV && Q.isUndefValue(FV))
387     return TV;
388 
389   // If applying the operation did not change the true and false select values,
390   // then the result of the binop is the select itself.
391   if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
392     return SI;
393 
394   // If one branch simplified and the other did not, and the simplified
395   // value is equal to the unsimplified one, return the simplified value.
396   // For example, select (cond, X, X & Z) & Z -> X & Z.
397   if ((FV && !TV) || (TV && !FV)) {
398     // Check that the simplified value has the form "X op Y" where "op" is the
399     // same as the original operation.
400     Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
401     if (Simplified && Simplified->getOpcode() == unsigned(Opcode) &&
402         !Simplified->hasPoisonGeneratingFlags()) {
403       // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
404       // We already know that "op" is the same as for the simplified value.  See
405       // if the operands match too.  If so, return the simplified value.
406       Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
407       Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
408       Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
409       if (Simplified->getOperand(0) == UnsimplifiedLHS &&
410           Simplified->getOperand(1) == UnsimplifiedRHS)
411         return Simplified;
412       if (Simplified->isCommutative() &&
413           Simplified->getOperand(1) == UnsimplifiedLHS &&
414           Simplified->getOperand(0) == UnsimplifiedRHS)
415         return Simplified;
416     }
417   }
418 
419   return nullptr;
420 }
421 
422 /// In the case of a comparison with a select instruction, try to simplify the
423 /// comparison by seeing whether both branches of the select result in the same
424 /// value. Returns the common value if so, otherwise returns null.
425 /// For example, if we have:
426 ///  %tmp = select i1 %cmp, i32 1, i32 2
427 ///  %cmp1 = icmp sle i32 %tmp, 3
428 /// We can simplify %cmp1 to true, because both branches of select are
429 /// less than 3. We compose new comparison by substituting %tmp with both
430 /// branches of select and see if it can be simplified.
threadCmpOverSelect(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)431 static Value *threadCmpOverSelect(CmpPredicate Pred, Value *LHS, Value *RHS,
432                                   const SimplifyQuery &Q, unsigned MaxRecurse) {
433   // Recursion is always used, so bail out at once if we already hit the limit.
434   if (!MaxRecurse--)
435     return nullptr;
436 
437   // Make sure the select is on the LHS.
438   if (!isa<SelectInst>(LHS)) {
439     std::swap(LHS, RHS);
440     Pred = CmpInst::getSwappedPredicate(Pred);
441   }
442   assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
443   SelectInst *SI = cast<SelectInst>(LHS);
444   Value *Cond = SI->getCondition();
445   Value *TV = SI->getTrueValue();
446   Value *FV = SI->getFalseValue();
447 
448   // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
449   // Does "cmp TV, RHS" simplify?
450   Value *TCmp = simplifyCmpSelTrueCase(Pred, TV, RHS, Cond, Q, MaxRecurse);
451   if (!TCmp)
452     return nullptr;
453 
454   // Does "cmp FV, RHS" simplify?
455   Value *FCmp = simplifyCmpSelFalseCase(Pred, FV, RHS, Cond, Q, MaxRecurse);
456   if (!FCmp)
457     return nullptr;
458 
459   // If both sides simplified to the same value, then use it as the result of
460   // the original comparison.
461   if (TCmp == FCmp)
462     return TCmp;
463 
464   // The remaining cases only make sense if the select condition has the same
465   // type as the result of the comparison, so bail out if this is not so.
466   if (Cond->getType()->isVectorTy() == RHS->getType()->isVectorTy())
467     return handleOtherCmpSelSimplifications(TCmp, FCmp, Cond, Q, MaxRecurse);
468 
469   return nullptr;
470 }
471 
472 /// In the case of a binary operation with an operand that is a PHI instruction,
473 /// try to simplify the binop by seeing whether evaluating it on the incoming
474 /// phi values yields the same result for every value. If so returns the common
475 /// value, otherwise returns null.
threadBinOpOverPHI(Instruction::BinaryOps Opcode,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)476 static Value *threadBinOpOverPHI(Instruction::BinaryOps Opcode, Value *LHS,
477                                  Value *RHS, const SimplifyQuery &Q,
478                                  unsigned MaxRecurse) {
479   // Recursion is always used, so bail out at once if we already hit the limit.
480   if (!MaxRecurse--)
481     return nullptr;
482 
483   PHINode *PI;
484   if (isa<PHINode>(LHS)) {
485     PI = cast<PHINode>(LHS);
486     // Bail out if RHS and the phi may be mutually interdependent due to a loop.
487     if (!valueDominatesPHI(RHS, PI, Q.DT))
488       return nullptr;
489   } else {
490     assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
491     PI = cast<PHINode>(RHS);
492     // Bail out if LHS and the phi may be mutually interdependent due to a loop.
493     if (!valueDominatesPHI(LHS, PI, Q.DT))
494       return nullptr;
495   }
496 
497   // Evaluate the BinOp on the incoming phi values.
498   Value *CommonValue = nullptr;
499   for (Use &Incoming : PI->incoming_values()) {
500     // If the incoming value is the phi node itself, it can safely be skipped.
501     if (Incoming == PI)
502       continue;
503     Instruction *InTI = PI->getIncomingBlock(Incoming)->getTerminator();
504     Value *V = PI == LHS
505                    ? simplifyBinOp(Opcode, Incoming, RHS,
506                                    Q.getWithInstruction(InTI), MaxRecurse)
507                    : simplifyBinOp(Opcode, LHS, Incoming,
508                                    Q.getWithInstruction(InTI), MaxRecurse);
509     // If the operation failed to simplify, or simplified to a different value
510     // to previously, then give up.
511     if (!V || (CommonValue && V != CommonValue))
512       return nullptr;
513     CommonValue = V;
514   }
515 
516   return CommonValue;
517 }
518 
519 /// In the case of a comparison with a PHI instruction, try to simplify the
520 /// comparison by seeing whether comparing with all of the incoming phi values
521 /// yields the same result every time. If so returns the common result,
522 /// otherwise returns null.
threadCmpOverPHI(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)523 static Value *threadCmpOverPHI(CmpPredicate Pred, Value *LHS, Value *RHS,
524                                const SimplifyQuery &Q, unsigned MaxRecurse) {
525   // Recursion is always used, so bail out at once if we already hit the limit.
526   if (!MaxRecurse--)
527     return nullptr;
528 
529   // Make sure the phi is on the LHS.
530   if (!isa<PHINode>(LHS)) {
531     std::swap(LHS, RHS);
532     Pred = CmpInst::getSwappedPredicate(Pred);
533   }
534   assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
535   PHINode *PI = cast<PHINode>(LHS);
536 
537   // Bail out if RHS and the phi may be mutually interdependent due to a loop.
538   if (!valueDominatesPHI(RHS, PI, Q.DT))
539     return nullptr;
540 
541   // Evaluate the BinOp on the incoming phi values.
542   Value *CommonValue = nullptr;
543   for (unsigned u = 0, e = PI->getNumIncomingValues(); u < e; ++u) {
544     Value *Incoming = PI->getIncomingValue(u);
545     Instruction *InTI = PI->getIncomingBlock(u)->getTerminator();
546     // If the incoming value is the phi node itself, it can safely be skipped.
547     if (Incoming == PI)
548       continue;
549     // Change the context instruction to the "edge" that flows into the phi.
550     // This is important because that is where incoming is actually "evaluated"
551     // even though it is used later somewhere else.
552     Value *V = simplifyCmpInst(Pred, Incoming, RHS, Q.getWithInstruction(InTI),
553                                MaxRecurse);
554     // If the operation failed to simplify, or simplified to a different value
555     // to previously, then give up.
556     if (!V || (CommonValue && V != CommonValue))
557       return nullptr;
558     CommonValue = V;
559   }
560 
561   return CommonValue;
562 }
563 
foldOrCommuteConstant(Instruction::BinaryOps Opcode,Value * & Op0,Value * & Op1,const SimplifyQuery & Q)564 static Constant *foldOrCommuteConstant(Instruction::BinaryOps Opcode,
565                                        Value *&Op0, Value *&Op1,
566                                        const SimplifyQuery &Q) {
567   if (auto *CLHS = dyn_cast<Constant>(Op0)) {
568     if (auto *CRHS = dyn_cast<Constant>(Op1)) {
569       switch (Opcode) {
570       default:
571         break;
572       case Instruction::FAdd:
573       case Instruction::FSub:
574       case Instruction::FMul:
575       case Instruction::FDiv:
576       case Instruction::FRem:
577         if (Q.CxtI != nullptr)
578           return ConstantFoldFPInstOperands(Opcode, CLHS, CRHS, Q.DL, Q.CxtI);
579       }
580       return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL);
581     }
582 
583     // Canonicalize the constant to the RHS if this is a commutative operation.
584     if (Instruction::isCommutative(Opcode))
585       std::swap(Op0, Op1);
586   }
587   return nullptr;
588 }
589 
590 /// Given operands for an Add, see if we can fold the result.
591 /// If not, this returns null.
simplifyAddInst(Value * Op0,Value * Op1,bool IsNSW,bool IsNUW,const SimplifyQuery & Q,unsigned MaxRecurse)592 static Value *simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
593                               const SimplifyQuery &Q, unsigned MaxRecurse) {
594   if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q))
595     return C;
596 
597   // X + poison -> poison
598   if (isa<PoisonValue>(Op1))
599     return Op1;
600 
601   // X + undef -> undef
602   if (Q.isUndefValue(Op1))
603     return Op1;
604 
605   // X + 0 -> X
606   if (match(Op1, m_Zero()))
607     return Op0;
608 
609   // If two operands are negative, return 0.
610   if (isKnownNegation(Op0, Op1))
611     return Constant::getNullValue(Op0->getType());
612 
613   // X + (Y - X) -> Y
614   // (Y - X) + X -> Y
615   // Eg: X + -X -> 0
616   Value *Y = nullptr;
617   if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
618       match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
619     return Y;
620 
621   // X + ~X -> -1   since   ~X = -X-1
622   Type *Ty = Op0->getType();
623   if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0))))
624     return Constant::getAllOnesValue(Ty);
625 
626   // add nsw/nuw (xor Y, signmask), signmask --> Y
627   // The no-wrapping add guarantees that the top bit will be set by the add.
628   // Therefore, the xor must be clearing the already set sign bit of Y.
629   if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) &&
630       match(Op0, m_Xor(m_Value(Y), m_SignMask())))
631     return Y;
632 
633   // add nuw %x, -1  ->  -1, because %x can only be 0.
634   if (IsNUW && match(Op1, m_AllOnes()))
635     return Op1; // Which is -1.
636 
637   /// i1 add -> xor.
638   if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
639     if (Value *V = simplifyXorInst(Op0, Op1, Q, MaxRecurse - 1))
640       return V;
641 
642   // Try some generic simplifications for associative operations.
643   if (Value *V =
644           simplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, MaxRecurse))
645     return V;
646 
647   // Threading Add over selects and phi nodes is pointless, so don't bother.
648   // Threading over the select in "A + select(cond, B, C)" means evaluating
649   // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
650   // only if B and C are equal.  If B and C are equal then (since we assume
651   // that operands have already been simplified) "select(cond, B, C)" should
652   // have been simplified to the common value of B and C already.  Analysing
653   // "A+B" and "A+C" thus gains nothing, but costs compile time.  Similarly
654   // for threading over phi nodes.
655 
656   return nullptr;
657 }
658 
simplifyAddInst(Value * Op0,Value * Op1,bool IsNSW,bool IsNUW,const SimplifyQuery & Query)659 Value *llvm::simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
660                              const SimplifyQuery &Query) {
661   return ::simplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit);
662 }
663 
664 /// Compute the base pointer and cumulative constant offsets for V.
665 ///
666 /// This strips all constant offsets off of V, leaving it the base pointer, and
667 /// accumulates the total constant offset applied in the returned constant.
668 /// It returns zero if there are no constant offsets applied.
669 ///
670 /// This is very similar to stripAndAccumulateConstantOffsets(), except it
671 /// normalizes the offset bitwidth to the stripped pointer type, not the
672 /// original pointer type.
stripAndComputeConstantOffsets(const DataLayout & DL,Value * & V,bool AllowNonInbounds=false)673 static APInt stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V,
674                                             bool AllowNonInbounds = false) {
675   assert(V->getType()->isPtrOrPtrVectorTy());
676 
677   APInt Offset = APInt::getZero(DL.getIndexTypeSizeInBits(V->getType()));
678   V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds);
679   // As that strip may trace through `addrspacecast`, need to sext or trunc
680   // the offset calculated.
681   return Offset.sextOrTrunc(DL.getIndexTypeSizeInBits(V->getType()));
682 }
683 
684 /// Compute the constant difference between two pointer values.
685 /// If the difference is not a constant, returns zero.
computePointerDifference(const DataLayout & DL,Value * LHS,Value * RHS)686 static Constant *computePointerDifference(const DataLayout &DL, Value *LHS,
687                                           Value *RHS) {
688   APInt LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
689   APInt RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
690 
691   // If LHS and RHS are not related via constant offsets to the same base
692   // value, there is nothing we can do here.
693   if (LHS != RHS)
694     return nullptr;
695 
696   // Otherwise, the difference of LHS - RHS can be computed as:
697   //    LHS - RHS
698   //  = (LHSOffset + Base) - (RHSOffset + Base)
699   //  = LHSOffset - RHSOffset
700   Constant *Res = ConstantInt::get(LHS->getContext(), LHSOffset - RHSOffset);
701   if (auto *VecTy = dyn_cast<VectorType>(LHS->getType()))
702     Res = ConstantVector::getSplat(VecTy->getElementCount(), Res);
703   return Res;
704 }
705 
706 /// Test if there is a dominating equivalence condition for the
707 /// two operands. If there is, try to reduce the binary operation
708 /// between the two operands.
709 /// Example: Op0 - Op1 --> 0 when Op0 == Op1
simplifyByDomEq(unsigned Opcode,Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)710 static Value *simplifyByDomEq(unsigned Opcode, Value *Op0, Value *Op1,
711                               const SimplifyQuery &Q, unsigned MaxRecurse) {
712   // Recursive run it can not get any benefit
713   if (MaxRecurse != RecursionLimit)
714     return nullptr;
715 
716   std::optional<bool> Imp =
717       isImpliedByDomCondition(CmpInst::ICMP_EQ, Op0, Op1, Q.CxtI, Q.DL);
718   if (Imp && *Imp) {
719     Type *Ty = Op0->getType();
720     switch (Opcode) {
721     case Instruction::Sub:
722     case Instruction::Xor:
723     case Instruction::URem:
724     case Instruction::SRem:
725       return Constant::getNullValue(Ty);
726 
727     case Instruction::SDiv:
728     case Instruction::UDiv:
729       return ConstantInt::get(Ty, 1);
730 
731     case Instruction::And:
732     case Instruction::Or:
733       // Could be either one - choose Op1 since that's more likely a constant.
734       return Op1;
735     default:
736       break;
737     }
738   }
739   return nullptr;
740 }
741 
742 /// Given operands for a Sub, see if we can fold the result.
743 /// If not, this returns null.
simplifySubInst(Value * Op0,Value * Op1,bool IsNSW,bool IsNUW,const SimplifyQuery & Q,unsigned MaxRecurse)744 static Value *simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
745                               const SimplifyQuery &Q, unsigned MaxRecurse) {
746   if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q))
747     return C;
748 
749   // X - poison -> poison
750   // poison - X -> poison
751   if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1))
752     return PoisonValue::get(Op0->getType());
753 
754   // X - undef -> undef
755   // undef - X -> undef
756   if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
757     return UndefValue::get(Op0->getType());
758 
759   // X - 0 -> X
760   if (match(Op1, m_Zero()))
761     return Op0;
762 
763   // X - X -> 0
764   if (Op0 == Op1)
765     return Constant::getNullValue(Op0->getType());
766 
767   // Is this a negation?
768   if (match(Op0, m_Zero())) {
769     // 0 - X -> 0 if the sub is NUW.
770     if (IsNUW)
771       return Constant::getNullValue(Op0->getType());
772 
773     KnownBits Known = computeKnownBits(Op1, Q);
774     if (Known.Zero.isMaxSignedValue()) {
775       // Op1 is either 0 or the minimum signed value. If the sub is NSW, then
776       // Op1 must be 0 because negating the minimum signed value is undefined.
777       if (IsNSW)
778         return Constant::getNullValue(Op0->getType());
779 
780       // 0 - X -> X if X is 0 or the minimum signed value.
781       return Op1;
782     }
783   }
784 
785   // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
786   // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
787   Value *X = nullptr, *Y = nullptr, *Z = Op1;
788   if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
789     // See if "V === Y - Z" simplifies.
790     if (Value *V = simplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse - 1))
791       // It does!  Now see if "X + V" simplifies.
792       if (Value *W = simplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse - 1)) {
793         // It does, we successfully reassociated!
794         ++NumReassoc;
795         return W;
796       }
797     // See if "V === X - Z" simplifies.
798     if (Value *V = simplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse - 1))
799       // It does!  Now see if "Y + V" simplifies.
800       if (Value *W = simplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse - 1)) {
801         // It does, we successfully reassociated!
802         ++NumReassoc;
803         return W;
804       }
805   }
806 
807   // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
808   // For example, X - (X + 1) -> -1
809   X = Op0;
810   if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
811     // See if "V === X - Y" simplifies.
812     if (Value *V = simplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse - 1))
813       // It does!  Now see if "V - Z" simplifies.
814       if (Value *W = simplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse - 1)) {
815         // It does, we successfully reassociated!
816         ++NumReassoc;
817         return W;
818       }
819     // See if "V === X - Z" simplifies.
820     if (Value *V = simplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse - 1))
821       // It does!  Now see if "V - Y" simplifies.
822       if (Value *W = simplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse - 1)) {
823         // It does, we successfully reassociated!
824         ++NumReassoc;
825         return W;
826       }
827   }
828 
829   // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
830   // For example, X - (X - Y) -> Y.
831   Z = Op0;
832   if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
833     // See if "V === Z - X" simplifies.
834     if (Value *V = simplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse - 1))
835       // It does!  Now see if "V + Y" simplifies.
836       if (Value *W = simplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse - 1)) {
837         // It does, we successfully reassociated!
838         ++NumReassoc;
839         return W;
840       }
841 
842   // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
843   if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
844       match(Op1, m_Trunc(m_Value(Y))))
845     if (X->getType() == Y->getType())
846       // See if "V === X - Y" simplifies.
847       if (Value *V = simplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse - 1))
848         // It does!  Now see if "trunc V" simplifies.
849         if (Value *W = simplifyCastInst(Instruction::Trunc, V, Op0->getType(),
850                                         Q, MaxRecurse - 1))
851           // It does, return the simplified "trunc V".
852           return W;
853 
854   // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
855   if (match(Op0, m_PtrToInt(m_Value(X))) && match(Op1, m_PtrToInt(m_Value(Y))))
856     if (Constant *Result = computePointerDifference(Q.DL, X, Y))
857       return ConstantFoldIntegerCast(Result, Op0->getType(), /*IsSigned*/ true,
858                                      Q.DL);
859 
860   // i1 sub -> xor.
861   if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
862     if (Value *V = simplifyXorInst(Op0, Op1, Q, MaxRecurse - 1))
863       return V;
864 
865   // Threading Sub over selects and phi nodes is pointless, so don't bother.
866   // Threading over the select in "A - select(cond, B, C)" means evaluating
867   // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
868   // only if B and C are equal.  If B and C are equal then (since we assume
869   // that operands have already been simplified) "select(cond, B, C)" should
870   // have been simplified to the common value of B and C already.  Analysing
871   // "A-B" and "A-C" thus gains nothing, but costs compile time.  Similarly
872   // for threading over phi nodes.
873 
874   if (Value *V = simplifyByDomEq(Instruction::Sub, Op0, Op1, Q, MaxRecurse))
875     return V;
876 
877   // (sub nuw C_Mask, (xor X, C_Mask)) -> X
878   if (IsNUW) {
879     Value *X;
880     if (match(Op1, m_Xor(m_Value(X), m_Specific(Op0))) &&
881         match(Op0, m_LowBitMask()))
882       return X;
883   }
884 
885   return nullptr;
886 }
887 
simplifySubInst(Value * Op0,Value * Op1,bool IsNSW,bool IsNUW,const SimplifyQuery & Q)888 Value *llvm::simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
889                              const SimplifyQuery &Q) {
890   return ::simplifySubInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit);
891 }
892 
893 /// Given operands for a Mul, see if we can fold the result.
894 /// If not, this returns null.
simplifyMulInst(Value * Op0,Value * Op1,bool IsNSW,bool IsNUW,const SimplifyQuery & Q,unsigned MaxRecurse)895 static Value *simplifyMulInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
896                               const SimplifyQuery &Q, unsigned MaxRecurse) {
897   if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q))
898     return C;
899 
900   // X * poison -> poison
901   if (isa<PoisonValue>(Op1))
902     return Op1;
903 
904   // X * undef -> 0
905   // X * 0 -> 0
906   if (Q.isUndefValue(Op1) || match(Op1, m_Zero()))
907     return Constant::getNullValue(Op0->getType());
908 
909   // X * 1 -> X
910   if (match(Op1, m_One()))
911     return Op0;
912 
913   // (X / Y) * Y -> X if the division is exact.
914   Value *X = nullptr;
915   if (Q.IIQ.UseInstrInfo &&
916       (match(Op0,
917              m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) ||     // (X / Y) * Y
918        match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))) // Y * (X / Y)
919     return X;
920 
921    if (Op0->getType()->isIntOrIntVectorTy(1)) {
922     // mul i1 nsw is a special-case because -1 * -1 is poison (+1 is not
923     // representable). All other cases reduce to 0, so just return 0.
924     if (IsNSW)
925       return ConstantInt::getNullValue(Op0->getType());
926 
927     // Treat "mul i1" as "and i1".
928     if (MaxRecurse)
929       if (Value *V = simplifyAndInst(Op0, Op1, Q, MaxRecurse - 1))
930         return V;
931   }
932 
933   // Try some generic simplifications for associative operations.
934   if (Value *V =
935           simplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, MaxRecurse))
936     return V;
937 
938   // Mul distributes over Add. Try some generic simplifications based on this.
939   if (Value *V = expandCommutativeBinOp(Instruction::Mul, Op0, Op1,
940                                         Instruction::Add, Q, MaxRecurse))
941     return V;
942 
943   // If the operation is with the result of a select instruction, check whether
944   // operating on either branch of the select always yields the same value.
945   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
946     if (Value *V =
947             threadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, MaxRecurse))
948       return V;
949 
950   // If the operation is with the result of a phi instruction, check whether
951   // operating on all incoming values of the phi always yields the same value.
952   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
953     if (Value *V =
954             threadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, MaxRecurse))
955       return V;
956 
957   return nullptr;
958 }
959 
simplifyMulInst(Value * Op0,Value * Op1,bool IsNSW,bool IsNUW,const SimplifyQuery & Q)960 Value *llvm::simplifyMulInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
961                              const SimplifyQuery &Q) {
962   return ::simplifyMulInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit);
963 }
964 
965 /// Given a predicate and two operands, return true if the comparison is true.
966 /// This is a helper for div/rem simplification where we return some other value
967 /// when we can prove a relationship between the operands.
isICmpTrue(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)968 static bool isICmpTrue(CmpPredicate Pred, Value *LHS, Value *RHS,
969                        const SimplifyQuery &Q, unsigned MaxRecurse) {
970   Value *V = simplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse);
971   Constant *C = dyn_cast_or_null<Constant>(V);
972   return (C && C->isAllOnesValue());
973 }
974 
975 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer
976 /// to simplify X % Y to X.
isDivZero(Value * X,Value * Y,const SimplifyQuery & Q,unsigned MaxRecurse,bool IsSigned)977 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q,
978                       unsigned MaxRecurse, bool IsSigned) {
979   // Recursion is always used, so bail out at once if we already hit the limit.
980   if (!MaxRecurse--)
981     return false;
982 
983   if (IsSigned) {
984     // (X srem Y) sdiv Y --> 0
985     if (match(X, m_SRem(m_Value(), m_Specific(Y))))
986       return true;
987 
988     // |X| / |Y| --> 0
989     //
990     // We require that 1 operand is a simple constant. That could be extended to
991     // 2 variables if we computed the sign bit for each.
992     //
993     // Make sure that a constant is not the minimum signed value because taking
994     // the abs() of that is undefined.
995     Type *Ty = X->getType();
996     const APInt *C;
997     if (match(X, m_APInt(C)) && !C->isMinSignedValue()) {
998       // Is the variable divisor magnitude always greater than the constant
999       // dividend magnitude?
1000       // |Y| > |C| --> Y < -abs(C) or Y > abs(C)
1001       Constant *PosDividendC = ConstantInt::get(Ty, C->abs());
1002       Constant *NegDividendC = ConstantInt::get(Ty, -C->abs());
1003       if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) ||
1004           isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse))
1005         return true;
1006     }
1007     if (match(Y, m_APInt(C))) {
1008       // Special-case: we can't take the abs() of a minimum signed value. If
1009       // that's the divisor, then all we have to do is prove that the dividend
1010       // is also not the minimum signed value.
1011       if (C->isMinSignedValue())
1012         return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse);
1013 
1014       // Is the variable dividend magnitude always less than the constant
1015       // divisor magnitude?
1016       // |X| < |C| --> X > -abs(C) and X < abs(C)
1017       Constant *PosDivisorC = ConstantInt::get(Ty, C->abs());
1018       Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs());
1019       if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) &&
1020           isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse))
1021         return true;
1022     }
1023     return false;
1024   }
1025 
1026   // IsSigned == false.
1027 
1028   // Is the unsigned dividend known to be less than a constant divisor?
1029   // TODO: Convert this (and above) to range analysis
1030   //      ("computeConstantRangeIncludingKnownBits")?
1031   const APInt *C;
1032   if (match(Y, m_APInt(C)) && computeKnownBits(X, Q).getMaxValue().ult(*C))
1033     return true;
1034 
1035   // Try again for any divisor:
1036   // Is the dividend unsigned less than the divisor?
1037   return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse);
1038 }
1039 
1040 /// Check for common or similar folds of integer division or integer remainder.
1041 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem).
simplifyDivRem(Instruction::BinaryOps Opcode,Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)1042 static Value *simplifyDivRem(Instruction::BinaryOps Opcode, Value *Op0,
1043                              Value *Op1, const SimplifyQuery &Q,
1044                              unsigned MaxRecurse) {
1045   bool IsDiv = (Opcode == Instruction::SDiv || Opcode == Instruction::UDiv);
1046   bool IsSigned = (Opcode == Instruction::SDiv || Opcode == Instruction::SRem);
1047 
1048   Type *Ty = Op0->getType();
1049 
1050   // X / undef -> poison
1051   // X % undef -> poison
1052   if (Q.isUndefValue(Op1) || isa<PoisonValue>(Op1))
1053     return PoisonValue::get(Ty);
1054 
1055   // X / 0 -> poison
1056   // X % 0 -> poison
1057   // We don't need to preserve faults!
1058   if (match(Op1, m_Zero()))
1059     return PoisonValue::get(Ty);
1060 
1061   // poison / X -> poison
1062   // poison % X -> poison
1063   if (isa<PoisonValue>(Op0))
1064     return Op0;
1065 
1066   // undef / X -> 0
1067   // undef % X -> 0
1068   if (Q.isUndefValue(Op0))
1069     return Constant::getNullValue(Ty);
1070 
1071   // 0 / X -> 0
1072   // 0 % X -> 0
1073   if (match(Op0, m_Zero()))
1074     return Constant::getNullValue(Op0->getType());
1075 
1076   // X / X -> 1
1077   // X % X -> 0
1078   if (Op0 == Op1)
1079     return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty);
1080 
1081   KnownBits Known = computeKnownBits(Op1, Q);
1082   // X / 0 -> poison
1083   // X % 0 -> poison
1084   // If the divisor is known to be zero, just return poison. This can happen in
1085   // some cases where its provable indirectly the denominator is zero but it's
1086   // not trivially simplifiable (i.e known zero through a phi node).
1087   if (Known.isZero())
1088     return PoisonValue::get(Ty);
1089 
1090   // X / 1 -> X
1091   // X % 1 -> 0
1092   // If the divisor can only be zero or one, we can't have division-by-zero
1093   // or remainder-by-zero, so assume the divisor is 1.
1094   //   e.g. 1, zext (i8 X), sdiv X (Y and 1)
1095   if (Known.countMinLeadingZeros() == Known.getBitWidth() - 1)
1096     return IsDiv ? Op0 : Constant::getNullValue(Ty);
1097 
1098   // If X * Y does not overflow, then:
1099   //   X * Y / Y -> X
1100   //   X * Y % Y -> 0
1101   Value *X;
1102   if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) {
1103     auto *Mul = cast<OverflowingBinaryOperator>(Op0);
1104     // The multiplication can't overflow if it is defined not to, or if
1105     // X == A / Y for some A.
1106     if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) ||
1107         (!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul)) ||
1108         (IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) ||
1109         (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1))))) {
1110       return IsDiv ? X : Constant::getNullValue(Op0->getType());
1111     }
1112   }
1113 
1114   if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned))
1115     return IsDiv ? Constant::getNullValue(Op0->getType()) : Op0;
1116 
1117   if (Value *V = simplifyByDomEq(Opcode, Op0, Op1, Q, MaxRecurse))
1118     return V;
1119 
1120   // If the operation is with the result of a select instruction, check whether
1121   // operating on either branch of the select always yields the same value.
1122   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1123     if (Value *V = threadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1124       return V;
1125 
1126   // If the operation is with the result of a phi instruction, check whether
1127   // operating on all incoming values of the phi always yields the same value.
1128   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1129     if (Value *V = threadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1130       return V;
1131 
1132   return nullptr;
1133 }
1134 
1135 /// These are simplifications common to SDiv and UDiv.
simplifyDiv(Instruction::BinaryOps Opcode,Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q,unsigned MaxRecurse)1136 static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1137                           bool IsExact, const SimplifyQuery &Q,
1138                           unsigned MaxRecurse) {
1139   if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1140     return C;
1141 
1142   if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse))
1143     return V;
1144 
1145   const APInt *DivC;
1146   if (IsExact && match(Op1, m_APInt(DivC))) {
1147     // If this is an exact divide by a constant, then the dividend (Op0) must
1148     // have at least as many trailing zeros as the divisor to divide evenly. If
1149     // it has less trailing zeros, then the result must be poison.
1150     if (DivC->countr_zero()) {
1151       KnownBits KnownOp0 = computeKnownBits(Op0, Q);
1152       if (KnownOp0.countMaxTrailingZeros() < DivC->countr_zero())
1153         return PoisonValue::get(Op0->getType());
1154     }
1155 
1156     // udiv exact (mul nsw X, C), C --> X
1157     // sdiv exact (mul nuw X, C), C --> X
1158     // where C is not a power of 2.
1159     Value *X;
1160     if (!DivC->isPowerOf2() &&
1161         (Opcode == Instruction::UDiv
1162              ? match(Op0, m_NSWMul(m_Value(X), m_Specific(Op1)))
1163              : match(Op0, m_NUWMul(m_Value(X), m_Specific(Op1)))))
1164       return X;
1165   }
1166 
1167   return nullptr;
1168 }
1169 
1170 /// These are simplifications common to SRem and URem.
simplifyRem(Instruction::BinaryOps Opcode,Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)1171 static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1172                           const SimplifyQuery &Q, unsigned MaxRecurse) {
1173   if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1174     return C;
1175 
1176   if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse))
1177     return V;
1178 
1179   // (X << Y) % X -> 0
1180   if (Q.IIQ.UseInstrInfo) {
1181     if ((Opcode == Instruction::SRem &&
1182          match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) ||
1183         (Opcode == Instruction::URem &&
1184          match(Op0, m_NUWShl(m_Specific(Op1), m_Value()))))
1185       return Constant::getNullValue(Op0->getType());
1186 
1187     const APInt *C0;
1188     if (match(Op1, m_APInt(C0))) {
1189       // (srem (mul nsw X, C1), C0) -> 0 if C1 s% C0 == 0
1190       // (urem (mul nuw X, C1), C0) -> 0 if C1 u% C0 == 0
1191       if (Opcode == Instruction::SRem
1192               ? match(Op0,
1193                       m_NSWMul(m_Value(), m_CheckedInt([C0](const APInt &C) {
1194                                  return C.srem(*C0).isZero();
1195                                })))
1196               : match(Op0,
1197                       m_NUWMul(m_Value(), m_CheckedInt([C0](const APInt &C) {
1198                                  return C.urem(*C0).isZero();
1199                                }))))
1200         return Constant::getNullValue(Op0->getType());
1201     }
1202   }
1203   return nullptr;
1204 }
1205 
1206 /// Given operands for an SDiv, see if we can fold the result.
1207 /// If not, this returns null.
simplifySDivInst(Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q,unsigned MaxRecurse)1208 static Value *simplifySDivInst(Value *Op0, Value *Op1, bool IsExact,
1209                                const SimplifyQuery &Q, unsigned MaxRecurse) {
1210   // If two operands are negated and no signed overflow, return -1.
1211   if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true))
1212     return Constant::getAllOnesValue(Op0->getType());
1213 
1214   return simplifyDiv(Instruction::SDiv, Op0, Op1, IsExact, Q, MaxRecurse);
1215 }
1216 
simplifySDivInst(Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q)1217 Value *llvm::simplifySDivInst(Value *Op0, Value *Op1, bool IsExact,
1218                               const SimplifyQuery &Q) {
1219   return ::simplifySDivInst(Op0, Op1, IsExact, Q, RecursionLimit);
1220 }
1221 
1222 /// Given operands for a UDiv, see if we can fold the result.
1223 /// If not, this returns null.
simplifyUDivInst(Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q,unsigned MaxRecurse)1224 static Value *simplifyUDivInst(Value *Op0, Value *Op1, bool IsExact,
1225                                const SimplifyQuery &Q, unsigned MaxRecurse) {
1226   return simplifyDiv(Instruction::UDiv, Op0, Op1, IsExact, Q, MaxRecurse);
1227 }
1228 
simplifyUDivInst(Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q)1229 Value *llvm::simplifyUDivInst(Value *Op0, Value *Op1, bool IsExact,
1230                               const SimplifyQuery &Q) {
1231   return ::simplifyUDivInst(Op0, Op1, IsExact, Q, RecursionLimit);
1232 }
1233 
1234 /// Given operands for an SRem, see if we can fold the result.
1235 /// If not, this returns null.
simplifySRemInst(Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)1236 static Value *simplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1237                                unsigned MaxRecurse) {
1238   // If the divisor is 0, the result is undefined, so assume the divisor is -1.
1239   // srem Op0, (sext i1 X) --> srem Op0, -1 --> 0
1240   Value *X;
1241   if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))
1242     return ConstantInt::getNullValue(Op0->getType());
1243 
1244   // If the two operands are negated, return 0.
1245   if (isKnownNegation(Op0, Op1))
1246     return ConstantInt::getNullValue(Op0->getType());
1247 
1248   return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse);
1249 }
1250 
simplifySRemInst(Value * Op0,Value * Op1,const SimplifyQuery & Q)1251 Value *llvm::simplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1252   return ::simplifySRemInst(Op0, Op1, Q, RecursionLimit);
1253 }
1254 
1255 /// Given operands for a URem, see if we can fold the result.
1256 /// If not, this returns null.
simplifyURemInst(Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)1257 static Value *simplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
1258                                unsigned MaxRecurse) {
1259   return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse);
1260 }
1261 
simplifyURemInst(Value * Op0,Value * Op1,const SimplifyQuery & Q)1262 Value *llvm::simplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
1263   return ::simplifyURemInst(Op0, Op1, Q, RecursionLimit);
1264 }
1265 
1266 /// Returns true if a shift by \c Amount always yields poison.
isPoisonShift(Value * Amount,const SimplifyQuery & Q)1267 static bool isPoisonShift(Value *Amount, const SimplifyQuery &Q) {
1268   Constant *C = dyn_cast<Constant>(Amount);
1269   if (!C)
1270     return false;
1271 
1272   // X shift by undef -> poison because it may shift by the bitwidth.
1273   if (Q.isUndefValue(C))
1274     return true;
1275 
1276   // Shifting by the bitwidth or more is poison. This covers scalars and
1277   // fixed/scalable vectors with splat constants.
1278   const APInt *AmountC;
1279   if (match(C, m_APInt(AmountC)) && AmountC->uge(AmountC->getBitWidth()))
1280     return true;
1281 
1282   // Try harder for fixed-length vectors:
1283   // If all lanes of a vector shift are poison, the whole shift is poison.
1284   if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
1285     for (unsigned I = 0,
1286                   E = cast<FixedVectorType>(C->getType())->getNumElements();
1287          I != E; ++I)
1288       if (!isPoisonShift(C->getAggregateElement(I), Q))
1289         return false;
1290     return true;
1291   }
1292 
1293   return false;
1294 }
1295 
1296 /// Given operands for an Shl, LShr or AShr, see if we can fold the result.
1297 /// If not, this returns null.
simplifyShift(Instruction::BinaryOps Opcode,Value * Op0,Value * Op1,bool IsNSW,const SimplifyQuery & Q,unsigned MaxRecurse)1298 static Value *simplifyShift(Instruction::BinaryOps Opcode, Value *Op0,
1299                             Value *Op1, bool IsNSW, const SimplifyQuery &Q,
1300                             unsigned MaxRecurse) {
1301   if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
1302     return C;
1303 
1304   // poison shift by X -> poison
1305   if (isa<PoisonValue>(Op0))
1306     return Op0;
1307 
1308   // 0 shift by X -> 0
1309   if (match(Op0, m_Zero()))
1310     return Constant::getNullValue(Op0->getType());
1311 
1312   // X shift by 0 -> X
1313   // Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones
1314   // would be poison.
1315   Value *X;
1316   if (match(Op1, m_Zero()) ||
1317       (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)))
1318     return Op0;
1319 
1320   // Fold undefined shifts.
1321   if (isPoisonShift(Op1, Q))
1322     return PoisonValue::get(Op0->getType());
1323 
1324   // If the operation is with the result of a select instruction, check whether
1325   // operating on either branch of the select always yields the same value.
1326   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1327     if (Value *V = threadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1328       return V;
1329 
1330   // If the operation is with the result of a phi instruction, check whether
1331   // operating on all incoming values of the phi always yields the same value.
1332   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1333     if (Value *V = threadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1334       return V;
1335 
1336   // If any bits in the shift amount make that value greater than or equal to
1337   // the number of bits in the type, the shift is undefined.
1338   KnownBits KnownAmt = computeKnownBits(Op1, Q);
1339   if (KnownAmt.getMinValue().uge(KnownAmt.getBitWidth()))
1340     return PoisonValue::get(Op0->getType());
1341 
1342   // If all valid bits in the shift amount are known zero, the first operand is
1343   // unchanged.
1344   unsigned NumValidShiftBits = Log2_32_Ceil(KnownAmt.getBitWidth());
1345   if (KnownAmt.countMinTrailingZeros() >= NumValidShiftBits)
1346     return Op0;
1347 
1348   // Check for nsw shl leading to a poison value.
1349   if (IsNSW) {
1350     assert(Opcode == Instruction::Shl && "Expected shl for nsw instruction");
1351     KnownBits KnownVal = computeKnownBits(Op0, Q);
1352     KnownBits KnownShl = KnownBits::shl(KnownVal, KnownAmt);
1353 
1354     if (KnownVal.Zero.isSignBitSet())
1355       KnownShl.Zero.setSignBit();
1356     if (KnownVal.One.isSignBitSet())
1357       KnownShl.One.setSignBit();
1358 
1359     if (KnownShl.hasConflict())
1360       return PoisonValue::get(Op0->getType());
1361   }
1362 
1363   return nullptr;
1364 }
1365 
1366 /// Given operands for an LShr or AShr, see if we can fold the result.  If not,
1367 /// this returns null.
simplifyRightShift(Instruction::BinaryOps Opcode,Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q,unsigned MaxRecurse)1368 static Value *simplifyRightShift(Instruction::BinaryOps Opcode, Value *Op0,
1369                                  Value *Op1, bool IsExact,
1370                                  const SimplifyQuery &Q, unsigned MaxRecurse) {
1371   if (Value *V =
1372           simplifyShift(Opcode, Op0, Op1, /*IsNSW*/ false, Q, MaxRecurse))
1373     return V;
1374 
1375   // X >> X -> 0
1376   if (Op0 == Op1)
1377     return Constant::getNullValue(Op0->getType());
1378 
1379   // undef >> X -> 0
1380   // undef >> X -> undef (if it's exact)
1381   if (Q.isUndefValue(Op0))
1382     return IsExact ? Op0 : Constant::getNullValue(Op0->getType());
1383 
1384   // The low bit cannot be shifted out of an exact shift if it is set.
1385   // TODO: Generalize by counting trailing zeros (see fold for exact division).
1386   if (IsExact) {
1387     KnownBits Op0Known = computeKnownBits(Op0, Q);
1388     if (Op0Known.One[0])
1389       return Op0;
1390   }
1391 
1392   return nullptr;
1393 }
1394 
1395 /// Given operands for an Shl, see if we can fold the result.
1396 /// If not, this returns null.
simplifyShlInst(Value * Op0,Value * Op1,bool IsNSW,bool IsNUW,const SimplifyQuery & Q,unsigned MaxRecurse)1397 static Value *simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
1398                               const SimplifyQuery &Q, unsigned MaxRecurse) {
1399   if (Value *V =
1400           simplifyShift(Instruction::Shl, Op0, Op1, IsNSW, Q, MaxRecurse))
1401     return V;
1402 
1403   Type *Ty = Op0->getType();
1404   // undef << X -> 0
1405   // undef << X -> undef if (if it's NSW/NUW)
1406   if (Q.isUndefValue(Op0))
1407     return IsNSW || IsNUW ? Op0 : Constant::getNullValue(Ty);
1408 
1409   // (X >> A) << A -> X
1410   Value *X;
1411   if (Q.IIQ.UseInstrInfo &&
1412       match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1413     return X;
1414 
1415   // shl nuw i8 C, %x  ->  C  iff C has sign bit set.
1416   if (IsNUW && match(Op0, m_Negative()))
1417     return Op0;
1418   // NOTE: could use computeKnownBits() / LazyValueInfo,
1419   // but the cost-benefit analysis suggests it isn't worth it.
1420 
1421   // "nuw" guarantees that only zeros are shifted out, and "nsw" guarantees
1422   // that the sign-bit does not change, so the only input that does not
1423   // produce poison is 0, and "0 << (bitwidth-1) --> 0".
1424   if (IsNSW && IsNUW &&
1425       match(Op1, m_SpecificInt(Ty->getScalarSizeInBits() - 1)))
1426     return Constant::getNullValue(Ty);
1427 
1428   return nullptr;
1429 }
1430 
simplifyShlInst(Value * Op0,Value * Op1,bool IsNSW,bool IsNUW,const SimplifyQuery & Q)1431 Value *llvm::simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
1432                              const SimplifyQuery &Q) {
1433   return ::simplifyShlInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit);
1434 }
1435 
1436 /// Given operands for an LShr, see if we can fold the result.
1437 /// If not, this returns null.
simplifyLShrInst(Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q,unsigned MaxRecurse)1438 static Value *simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact,
1439                                const SimplifyQuery &Q, unsigned MaxRecurse) {
1440   if (Value *V = simplifyRightShift(Instruction::LShr, Op0, Op1, IsExact, Q,
1441                                     MaxRecurse))
1442     return V;
1443 
1444   // (X << A) >> A -> X
1445   Value *X;
1446   if (Q.IIQ.UseInstrInfo && match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
1447     return X;
1448 
1449   // ((X << A) | Y) >> A -> X  if effective width of Y is not larger than A.
1450   // We can return X as we do in the above case since OR alters no bits in X.
1451   // SimplifyDemandedBits in InstCombine can do more general optimization for
1452   // bit manipulation. This pattern aims to provide opportunities for other
1453   // optimizers by supporting a simple but common case in InstSimplify.
1454   Value *Y;
1455   const APInt *ShRAmt, *ShLAmt;
1456   if (Q.IIQ.UseInstrInfo && match(Op1, m_APInt(ShRAmt)) &&
1457       match(Op0, m_c_Or(m_NUWShl(m_Value(X), m_APInt(ShLAmt)), m_Value(Y))) &&
1458       *ShRAmt == *ShLAmt) {
1459     const KnownBits YKnown = computeKnownBits(Y, Q);
1460     const unsigned EffWidthY = YKnown.countMaxActiveBits();
1461     if (ShRAmt->uge(EffWidthY))
1462       return X;
1463   }
1464 
1465   return nullptr;
1466 }
1467 
simplifyLShrInst(Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q)1468 Value *llvm::simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact,
1469                               const SimplifyQuery &Q) {
1470   return ::simplifyLShrInst(Op0, Op1, IsExact, Q, RecursionLimit);
1471 }
1472 
1473 /// Given operands for an AShr, see if we can fold the result.
1474 /// If not, this returns null.
simplifyAShrInst(Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q,unsigned MaxRecurse)1475 static Value *simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact,
1476                                const SimplifyQuery &Q, unsigned MaxRecurse) {
1477   if (Value *V = simplifyRightShift(Instruction::AShr, Op0, Op1, IsExact, Q,
1478                                     MaxRecurse))
1479     return V;
1480 
1481   // -1 >>a X --> -1
1482   // (-1 << X) a>> X --> -1
1483   // We could return the original -1 constant to preserve poison elements.
1484   if (match(Op0, m_AllOnes()) ||
1485       match(Op0, m_Shl(m_AllOnes(), m_Specific(Op1))))
1486     return Constant::getAllOnesValue(Op0->getType());
1487 
1488   // (X << A) >> A -> X
1489   Value *X;
1490   if (Q.IIQ.UseInstrInfo && match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
1491     return X;
1492 
1493   // Arithmetic shifting an all-sign-bit value is a no-op.
1494   unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, Q.AC, Q.CxtI, Q.DT);
1495   if (NumSignBits == Op0->getType()->getScalarSizeInBits())
1496     return Op0;
1497 
1498   return nullptr;
1499 }
1500 
simplifyAShrInst(Value * Op0,Value * Op1,bool IsExact,const SimplifyQuery & Q)1501 Value *llvm::simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact,
1502                               const SimplifyQuery &Q) {
1503   return ::simplifyAShrInst(Op0, Op1, IsExact, Q, RecursionLimit);
1504 }
1505 
1506 /// Commuted variants are assumed to be handled by calling this function again
1507 /// with the parameters swapped.
simplifyUnsignedRangeCheck(ICmpInst * ZeroICmp,ICmpInst * UnsignedICmp,bool IsAnd,const SimplifyQuery & Q)1508 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp,
1509                                          ICmpInst *UnsignedICmp, bool IsAnd,
1510                                          const SimplifyQuery &Q) {
1511   Value *X, *Y;
1512 
1513   CmpPredicate EqPred;
1514   if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) ||
1515       !ICmpInst::isEquality(EqPred))
1516     return nullptr;
1517 
1518   CmpPredicate UnsignedPred;
1519 
1520   Value *A, *B;
1521   // Y = (A - B);
1522   if (match(Y, m_Sub(m_Value(A), m_Value(B)))) {
1523     if (match(UnsignedICmp,
1524               m_c_ICmp(UnsignedPred, m_Specific(A), m_Specific(B))) &&
1525         ICmpInst::isUnsigned(UnsignedPred)) {
1526       // A >=/<= B || (A - B) != 0  <-->  true
1527       if ((UnsignedPred == ICmpInst::ICMP_UGE ||
1528            UnsignedPred == ICmpInst::ICMP_ULE) &&
1529           EqPred == ICmpInst::ICMP_NE && !IsAnd)
1530         return ConstantInt::getTrue(UnsignedICmp->getType());
1531       // A </> B && (A - B) == 0  <-->  false
1532       if ((UnsignedPred == ICmpInst::ICMP_ULT ||
1533            UnsignedPred == ICmpInst::ICMP_UGT) &&
1534           EqPred == ICmpInst::ICMP_EQ && IsAnd)
1535         return ConstantInt::getFalse(UnsignedICmp->getType());
1536 
1537       // A </> B && (A - B) != 0  <-->  A </> B
1538       // A </> B || (A - B) != 0  <-->  (A - B) != 0
1539       if (EqPred == ICmpInst::ICMP_NE && (UnsignedPred == ICmpInst::ICMP_ULT ||
1540                                           UnsignedPred == ICmpInst::ICMP_UGT))
1541         return IsAnd ? UnsignedICmp : ZeroICmp;
1542 
1543       // A <=/>= B && (A - B) == 0  <-->  (A - B) == 0
1544       // A <=/>= B || (A - B) == 0  <-->  A <=/>= B
1545       if (EqPred == ICmpInst::ICMP_EQ && (UnsignedPred == ICmpInst::ICMP_ULE ||
1546                                           UnsignedPred == ICmpInst::ICMP_UGE))
1547         return IsAnd ? ZeroICmp : UnsignedICmp;
1548     }
1549 
1550     // Given  Y = (A - B)
1551     //   Y >= A && Y != 0  --> Y >= A  iff B != 0
1552     //   Y <  A || Y == 0  --> Y <  A  iff B != 0
1553     if (match(UnsignedICmp,
1554               m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) {
1555       if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd &&
1556           EqPred == ICmpInst::ICMP_NE && isKnownNonZero(B, Q))
1557         return UnsignedICmp;
1558       if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd &&
1559           EqPred == ICmpInst::ICMP_EQ && isKnownNonZero(B, Q))
1560         return UnsignedICmp;
1561     }
1562   }
1563 
1564   if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
1565       ICmpInst::isUnsigned(UnsignedPred))
1566     ;
1567   else if (match(UnsignedICmp,
1568                  m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) &&
1569            ICmpInst::isUnsigned(UnsignedPred))
1570     UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
1571   else
1572     return nullptr;
1573 
1574   // X > Y && Y == 0  -->  Y == 0  iff X != 0
1575   // X > Y || Y == 0  -->  X > Y   iff X != 0
1576   if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ &&
1577       isKnownNonZero(X, Q))
1578     return IsAnd ? ZeroICmp : UnsignedICmp;
1579 
1580   // X <= Y && Y != 0  -->  X <= Y  iff X != 0
1581   // X <= Y || Y != 0  -->  Y != 0  iff X != 0
1582   if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE &&
1583       isKnownNonZero(X, Q))
1584     return IsAnd ? UnsignedICmp : ZeroICmp;
1585 
1586   // The transforms below here are expected to be handled more generally with
1587   // simplifyAndOrOfICmpsWithLimitConst() or in InstCombine's
1588   // foldAndOrOfICmpsWithConstEq(). If we are looking to trim optimizer overlap,
1589   // these are candidates for removal.
1590 
1591   // X < Y && Y != 0  -->  X < Y
1592   // X < Y || Y != 0  -->  Y != 0
1593   if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE)
1594     return IsAnd ? UnsignedICmp : ZeroICmp;
1595 
1596   // X >= Y && Y == 0  -->  Y == 0
1597   // X >= Y || Y == 0  -->  X >= Y
1598   if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ)
1599     return IsAnd ? ZeroICmp : UnsignedICmp;
1600 
1601   // X < Y && Y == 0  -->  false
1602   if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
1603       IsAnd)
1604     return getFalse(UnsignedICmp->getType());
1605 
1606   // X >= Y || Y != 0  -->  true
1607   if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_NE &&
1608       !IsAnd)
1609     return getTrue(UnsignedICmp->getType());
1610 
1611   return nullptr;
1612 }
1613 
1614 /// Test if a pair of compares with a shared operand and 2 constants has an
1615 /// empty set intersection, full set union, or if one compare is a superset of
1616 /// the other.
simplifyAndOrOfICmpsWithConstants(ICmpInst * Cmp0,ICmpInst * Cmp1,bool IsAnd)1617 static Value *simplifyAndOrOfICmpsWithConstants(ICmpInst *Cmp0, ICmpInst *Cmp1,
1618                                                 bool IsAnd) {
1619   // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)).
1620   if (Cmp0->getOperand(0) != Cmp1->getOperand(0))
1621     return nullptr;
1622 
1623   const APInt *C0, *C1;
1624   if (!match(Cmp0->getOperand(1), m_APInt(C0)) ||
1625       !match(Cmp1->getOperand(1), m_APInt(C1)))
1626     return nullptr;
1627 
1628   auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0);
1629   auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1);
1630 
1631   // For and-of-compares, check if the intersection is empty:
1632   // (icmp X, C0) && (icmp X, C1) --> empty set --> false
1633   if (IsAnd && Range0.intersectWith(Range1).isEmptySet())
1634     return getFalse(Cmp0->getType());
1635 
1636   // For or-of-compares, check if the union is full:
1637   // (icmp X, C0) || (icmp X, C1) --> full set --> true
1638   if (!IsAnd && Range0.unionWith(Range1).isFullSet())
1639     return getTrue(Cmp0->getType());
1640 
1641   // Is one range a superset of the other?
1642   // If this is and-of-compares, take the smaller set:
1643   // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42
1644   // If this is or-of-compares, take the larger set:
1645   // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4
1646   if (Range0.contains(Range1))
1647     return IsAnd ? Cmp1 : Cmp0;
1648   if (Range1.contains(Range0))
1649     return IsAnd ? Cmp0 : Cmp1;
1650 
1651   return nullptr;
1652 }
1653 
simplifyAndOfICmpsWithAdd(ICmpInst * Op0,ICmpInst * Op1,const InstrInfoQuery & IIQ)1654 static Value *simplifyAndOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1,
1655                                         const InstrInfoQuery &IIQ) {
1656   // (icmp (add V, C0), C1) & (icmp V, C0)
1657   CmpPredicate Pred0, Pred1;
1658   const APInt *C0, *C1;
1659   Value *V;
1660   if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1661     return nullptr;
1662 
1663   if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1664     return nullptr;
1665 
1666   auto *AddInst = cast<OverflowingBinaryOperator>(Op0->getOperand(0));
1667   if (AddInst->getOperand(1) != Op1->getOperand(1))
1668     return nullptr;
1669 
1670   Type *ITy = Op0->getType();
1671   bool IsNSW = IIQ.hasNoSignedWrap(AddInst);
1672   bool IsNUW = IIQ.hasNoUnsignedWrap(AddInst);
1673 
1674   const APInt Delta = *C1 - *C0;
1675   if (C0->isStrictlyPositive()) {
1676     if (Delta == 2) {
1677       if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
1678         return getFalse(ITy);
1679       if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && IsNSW)
1680         return getFalse(ITy);
1681     }
1682     if (Delta == 1) {
1683       if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
1684         return getFalse(ITy);
1685       if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && IsNSW)
1686         return getFalse(ITy);
1687     }
1688   }
1689   if (C0->getBoolValue() && IsNUW) {
1690     if (Delta == 2)
1691       if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
1692         return getFalse(ITy);
1693     if (Delta == 1)
1694       if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
1695         return getFalse(ITy);
1696   }
1697 
1698   return nullptr;
1699 }
1700 
1701 /// Try to simplify and/or of icmp with ctpop intrinsic.
simplifyAndOrOfICmpsWithCtpop(ICmpInst * Cmp0,ICmpInst * Cmp1,bool IsAnd)1702 static Value *simplifyAndOrOfICmpsWithCtpop(ICmpInst *Cmp0, ICmpInst *Cmp1,
1703                                             bool IsAnd) {
1704   CmpPredicate Pred0, Pred1;
1705   Value *X;
1706   const APInt *C;
1707   if (!match(Cmp0, m_ICmp(Pred0, m_Intrinsic<Intrinsic::ctpop>(m_Value(X)),
1708                           m_APInt(C))) ||
1709       !match(Cmp1, m_ICmp(Pred1, m_Specific(X), m_ZeroInt())) || C->isZero())
1710     return nullptr;
1711 
1712   // (ctpop(X) == C) || (X != 0) --> X != 0 where C > 0
1713   if (!IsAnd && Pred0 == ICmpInst::ICMP_EQ && Pred1 == ICmpInst::ICMP_NE)
1714     return Cmp1;
1715   // (ctpop(X) != C) && (X == 0) --> X == 0 where C > 0
1716   if (IsAnd && Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_EQ)
1717     return Cmp1;
1718 
1719   return nullptr;
1720 }
1721 
simplifyAndOfICmps(ICmpInst * Op0,ICmpInst * Op1,const SimplifyQuery & Q)1722 static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1,
1723                                  const SimplifyQuery &Q) {
1724   if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true, Q))
1725     return X;
1726   if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true, Q))
1727     return X;
1728 
1729   if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true))
1730     return X;
1731 
1732   if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op0, Op1, true))
1733     return X;
1734   if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op1, Op0, true))
1735     return X;
1736 
1737   if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1, Q.IIQ))
1738     return X;
1739   if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0, Q.IIQ))
1740     return X;
1741 
1742   return nullptr;
1743 }
1744 
simplifyOrOfICmpsWithAdd(ICmpInst * Op0,ICmpInst * Op1,const InstrInfoQuery & IIQ)1745 static Value *simplifyOrOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1,
1746                                        const InstrInfoQuery &IIQ) {
1747   // (icmp (add V, C0), C1) | (icmp V, C0)
1748   CmpPredicate Pred0, Pred1;
1749   const APInt *C0, *C1;
1750   Value *V;
1751   if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
1752     return nullptr;
1753 
1754   if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
1755     return nullptr;
1756 
1757   auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
1758   if (AddInst->getOperand(1) != Op1->getOperand(1))
1759     return nullptr;
1760 
1761   Type *ITy = Op0->getType();
1762   bool IsNSW = IIQ.hasNoSignedWrap(AddInst);
1763   bool IsNUW = IIQ.hasNoUnsignedWrap(AddInst);
1764 
1765   const APInt Delta = *C1 - *C0;
1766   if (C0->isStrictlyPositive()) {
1767     if (Delta == 2) {
1768       if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
1769         return getTrue(ITy);
1770       if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && IsNSW)
1771         return getTrue(ITy);
1772     }
1773     if (Delta == 1) {
1774       if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
1775         return getTrue(ITy);
1776       if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && IsNSW)
1777         return getTrue(ITy);
1778     }
1779   }
1780   if (C0->getBoolValue() && IsNUW) {
1781     if (Delta == 2)
1782       if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
1783         return getTrue(ITy);
1784     if (Delta == 1)
1785       if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
1786         return getTrue(ITy);
1787   }
1788 
1789   return nullptr;
1790 }
1791 
simplifyOrOfICmps(ICmpInst * Op0,ICmpInst * Op1,const SimplifyQuery & Q)1792 static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1,
1793                                 const SimplifyQuery &Q) {
1794   if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false, Q))
1795     return X;
1796   if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false, Q))
1797     return X;
1798 
1799   if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false))
1800     return X;
1801 
1802   if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op0, Op1, false))
1803     return X;
1804   if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op1, Op0, false))
1805     return X;
1806 
1807   if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, Q.IIQ))
1808     return X;
1809   if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, Q.IIQ))
1810     return X;
1811 
1812   return nullptr;
1813 }
1814 
simplifyAndOrOfFCmps(const SimplifyQuery & Q,FCmpInst * LHS,FCmpInst * RHS,bool IsAnd)1815 static Value *simplifyAndOrOfFCmps(const SimplifyQuery &Q, FCmpInst *LHS,
1816                                    FCmpInst *RHS, bool IsAnd) {
1817   Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
1818   Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
1819   if (LHS0->getType() != RHS0->getType())
1820     return nullptr;
1821 
1822   FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
1823   auto AbsOrSelfLHS0 = m_CombineOr(m_Specific(LHS0), m_FAbs(m_Specific(LHS0)));
1824   if ((PredL == FCmpInst::FCMP_ORD || PredL == FCmpInst::FCMP_UNO) &&
1825       ((FCmpInst::isOrdered(PredR) && IsAnd) ||
1826        (FCmpInst::isUnordered(PredR) && !IsAnd))) {
1827     // (fcmp ord X, 0) & (fcmp o** X/abs(X), Y) --> fcmp o** X/abs(X), Y
1828     // (fcmp uno X, 0) & (fcmp o** X/abs(X), Y) --> false
1829     // (fcmp uno X, 0) | (fcmp u** X/abs(X), Y) --> fcmp u** X/abs(X), Y
1830     // (fcmp ord X, 0) | (fcmp u** X/abs(X), Y) --> true
1831     if ((match(RHS0, AbsOrSelfLHS0) || match(RHS1, AbsOrSelfLHS0)) &&
1832         match(LHS1, m_PosZeroFP()))
1833       return FCmpInst::isOrdered(PredL) == FCmpInst::isOrdered(PredR)
1834                  ? static_cast<Value *>(RHS)
1835                  : ConstantInt::getBool(LHS->getType(), !IsAnd);
1836   }
1837 
1838   auto AbsOrSelfRHS0 = m_CombineOr(m_Specific(RHS0), m_FAbs(m_Specific(RHS0)));
1839   if ((PredR == FCmpInst::FCMP_ORD || PredR == FCmpInst::FCMP_UNO) &&
1840       ((FCmpInst::isOrdered(PredL) && IsAnd) ||
1841        (FCmpInst::isUnordered(PredL) && !IsAnd))) {
1842     // (fcmp o** X/abs(X), Y) & (fcmp ord X, 0) --> fcmp o** X/abs(X), Y
1843     // (fcmp o** X/abs(X), Y) & (fcmp uno X, 0) --> false
1844     // (fcmp u** X/abs(X), Y) | (fcmp uno X, 0) --> fcmp u** X/abs(X), Y
1845     // (fcmp u** X/abs(X), Y) | (fcmp ord X, 0) --> true
1846     if ((match(LHS0, AbsOrSelfRHS0) || match(LHS1, AbsOrSelfRHS0)) &&
1847         match(RHS1, m_PosZeroFP()))
1848       return FCmpInst::isOrdered(PredL) == FCmpInst::isOrdered(PredR)
1849                  ? static_cast<Value *>(LHS)
1850                  : ConstantInt::getBool(LHS->getType(), !IsAnd);
1851   }
1852 
1853   return nullptr;
1854 }
1855 
simplifyAndOrOfCmps(const SimplifyQuery & Q,Value * Op0,Value * Op1,bool IsAnd)1856 static Value *simplifyAndOrOfCmps(const SimplifyQuery &Q, Value *Op0,
1857                                   Value *Op1, bool IsAnd) {
1858   // Look through casts of the 'and' operands to find compares.
1859   auto *Cast0 = dyn_cast<CastInst>(Op0);
1860   auto *Cast1 = dyn_cast<CastInst>(Op1);
1861   if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() &&
1862       Cast0->getSrcTy() == Cast1->getSrcTy()) {
1863     Op0 = Cast0->getOperand(0);
1864     Op1 = Cast1->getOperand(0);
1865   }
1866 
1867   Value *V = nullptr;
1868   auto *ICmp0 = dyn_cast<ICmpInst>(Op0);
1869   auto *ICmp1 = dyn_cast<ICmpInst>(Op1);
1870   if (ICmp0 && ICmp1)
1871     V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1, Q)
1872               : simplifyOrOfICmps(ICmp0, ICmp1, Q);
1873 
1874   auto *FCmp0 = dyn_cast<FCmpInst>(Op0);
1875   auto *FCmp1 = dyn_cast<FCmpInst>(Op1);
1876   if (FCmp0 && FCmp1)
1877     V = simplifyAndOrOfFCmps(Q, FCmp0, FCmp1, IsAnd);
1878 
1879   if (!V)
1880     return nullptr;
1881   if (!Cast0)
1882     return V;
1883 
1884   // If we looked through casts, we can only handle a constant simplification
1885   // because we are not allowed to create a cast instruction here.
1886   if (auto *C = dyn_cast<Constant>(V))
1887     return ConstantFoldCastOperand(Cast0->getOpcode(), C, Cast0->getType(),
1888                                    Q.DL);
1889 
1890   return nullptr;
1891 }
1892 
1893 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
1894                                      const SimplifyQuery &Q,
1895                                      bool AllowRefinement,
1896                                      SmallVectorImpl<Instruction *> *DropFlags,
1897                                      unsigned MaxRecurse);
1898 
simplifyAndOrWithICmpEq(unsigned Opcode,Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)1899 static Value *simplifyAndOrWithICmpEq(unsigned Opcode, Value *Op0, Value *Op1,
1900                                       const SimplifyQuery &Q,
1901                                       unsigned MaxRecurse) {
1902   assert((Opcode == Instruction::And || Opcode == Instruction::Or) &&
1903          "Must be and/or");
1904   CmpPredicate Pred;
1905   Value *A, *B;
1906   if (!match(Op0, m_ICmp(Pred, m_Value(A), m_Value(B))) ||
1907       !ICmpInst::isEquality(Pred))
1908     return nullptr;
1909 
1910   auto Simplify = [&](Value *Res) -> Value * {
1911     Constant *Absorber = ConstantExpr::getBinOpAbsorber(Opcode, Res->getType());
1912 
1913     // and (icmp eq a, b), x implies (a==b) inside x.
1914     // or (icmp ne a, b), x implies (a==b) inside x.
1915     // If x simplifies to true/false, we can simplify the and/or.
1916     if (Pred ==
1917         (Opcode == Instruction::And ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE)) {
1918       if (Res == Absorber)
1919         return Absorber;
1920       if (Res == ConstantExpr::getBinOpIdentity(Opcode, Res->getType()))
1921         return Op0;
1922       return nullptr;
1923     }
1924 
1925     // If we have and (icmp ne a, b), x and for a==b we can simplify x to false,
1926     // then we can drop the icmp, as x will already be false in the case where
1927     // the icmp is false. Similar for or and true.
1928     if (Res == Absorber)
1929       return Op1;
1930     return nullptr;
1931   };
1932 
1933   // In the final case (Res == Absorber with inverted predicate), it is safe to
1934   // refine poison during simplification, but not undef. For simplicity always
1935   // disable undef-based folds here.
1936   if (Value *Res = simplifyWithOpReplaced(Op1, A, B, Q.getWithoutUndef(),
1937                                           /* AllowRefinement */ true,
1938                                           /* DropFlags */ nullptr, MaxRecurse))
1939     return Simplify(Res);
1940   if (Value *Res = simplifyWithOpReplaced(Op1, B, A, Q.getWithoutUndef(),
1941                                           /* AllowRefinement */ true,
1942                                           /* DropFlags */ nullptr, MaxRecurse))
1943     return Simplify(Res);
1944 
1945   return nullptr;
1946 }
1947 
1948 /// Given a bitwise logic op, check if the operands are add/sub with a common
1949 /// source value and inverted constant (identity: C - X -> ~(X + ~C)).
simplifyLogicOfAddSub(Value * Op0,Value * Op1,Instruction::BinaryOps Opcode)1950 static Value *simplifyLogicOfAddSub(Value *Op0, Value *Op1,
1951                                     Instruction::BinaryOps Opcode) {
1952   assert(Op0->getType() == Op1->getType() && "Mismatched binop types");
1953   assert(BinaryOperator::isBitwiseLogicOp(Opcode) && "Expected logic op");
1954   Value *X;
1955   Constant *C1, *C2;
1956   if ((match(Op0, m_Add(m_Value(X), m_Constant(C1))) &&
1957        match(Op1, m_Sub(m_Constant(C2), m_Specific(X)))) ||
1958       (match(Op1, m_Add(m_Value(X), m_Constant(C1))) &&
1959        match(Op0, m_Sub(m_Constant(C2), m_Specific(X))))) {
1960     if (ConstantExpr::getNot(C1) == C2) {
1961       // (X + C) & (~C - X) --> (X + C) & ~(X + C) --> 0
1962       // (X + C) | (~C - X) --> (X + C) | ~(X + C) --> -1
1963       // (X + C) ^ (~C - X) --> (X + C) ^ ~(X + C) --> -1
1964       Type *Ty = Op0->getType();
1965       return Opcode == Instruction::And ? ConstantInt::getNullValue(Ty)
1966                                         : ConstantInt::getAllOnesValue(Ty);
1967     }
1968   }
1969   return nullptr;
1970 }
1971 
1972 // Commutative patterns for and that will be tried with both operand orders.
simplifyAndCommutative(Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)1973 static Value *simplifyAndCommutative(Value *Op0, Value *Op1,
1974                                      const SimplifyQuery &Q,
1975                                      unsigned MaxRecurse) {
1976   // ~A & A =  0
1977   if (match(Op0, m_Not(m_Specific(Op1))))
1978     return Constant::getNullValue(Op0->getType());
1979 
1980   // (A | ?) & A = A
1981   if (match(Op0, m_c_Or(m_Specific(Op1), m_Value())))
1982     return Op1;
1983 
1984   // (X | ~Y) & (X | Y) --> X
1985   Value *X, *Y;
1986   if (match(Op0, m_c_Or(m_Value(X), m_Not(m_Value(Y)))) &&
1987       match(Op1, m_c_Or(m_Specific(X), m_Specific(Y))))
1988     return X;
1989 
1990   // If we have a multiplication overflow check that is being 'and'ed with a
1991   // check that one of the multipliers is not zero, we can omit the 'and', and
1992   // only keep the overflow check.
1993   if (isCheckForZeroAndMulWithOverflow(Op0, Op1, true))
1994     return Op1;
1995 
1996   // -A & A = A if A is a power of two or zero.
1997   if (match(Op0, m_Neg(m_Specific(Op1))) &&
1998       isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, Q.AC, Q.CxtI, Q.DT))
1999     return Op1;
2000 
2001   // This is a similar pattern used for checking if a value is a power-of-2:
2002   // (A - 1) & A --> 0 (if A is a power-of-2 or 0)
2003   if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) &&
2004       isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, Q.AC, Q.CxtI, Q.DT))
2005     return Constant::getNullValue(Op1->getType());
2006 
2007   // (x << N) & ((x << M) - 1) --> 0, where x is known to be a power of 2 and
2008   // M <= N.
2009   const APInt *Shift1, *Shift2;
2010   if (match(Op0, m_Shl(m_Value(X), m_APInt(Shift1))) &&
2011       match(Op1, m_Add(m_Shl(m_Specific(X), m_APInt(Shift2)), m_AllOnes())) &&
2012       isKnownToBeAPowerOfTwo(X, Q.DL, /*OrZero*/ true, Q.AC, Q.CxtI) &&
2013       Shift1->uge(*Shift2))
2014     return Constant::getNullValue(Op0->getType());
2015 
2016   if (Value *V =
2017           simplifyAndOrWithICmpEq(Instruction::And, Op0, Op1, Q, MaxRecurse))
2018     return V;
2019 
2020   return nullptr;
2021 }
2022 
2023 /// Given operands for an And, see if we can fold the result.
2024 /// If not, this returns null.
simplifyAndInst(Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)2025 static Value *simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
2026                               unsigned MaxRecurse) {
2027   if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q))
2028     return C;
2029 
2030   // X & poison -> poison
2031   if (isa<PoisonValue>(Op1))
2032     return Op1;
2033 
2034   // X & undef -> 0
2035   if (Q.isUndefValue(Op1))
2036     return Constant::getNullValue(Op0->getType());
2037 
2038   // X & X = X
2039   if (Op0 == Op1)
2040     return Op0;
2041 
2042   // X & 0 = 0
2043   if (match(Op1, m_Zero()))
2044     return Constant::getNullValue(Op0->getType());
2045 
2046   // X & -1 = X
2047   if (match(Op1, m_AllOnes()))
2048     return Op0;
2049 
2050   if (Value *Res = simplifyAndCommutative(Op0, Op1, Q, MaxRecurse))
2051     return Res;
2052   if (Value *Res = simplifyAndCommutative(Op1, Op0, Q, MaxRecurse))
2053     return Res;
2054 
2055   if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::And))
2056     return V;
2057 
2058   // A mask that only clears known zeros of a shifted value is a no-op.
2059   const APInt *Mask;
2060   const APInt *ShAmt;
2061   Value *X, *Y;
2062   if (match(Op1, m_APInt(Mask))) {
2063     // If all bits in the inverted and shifted mask are clear:
2064     // and (shl X, ShAmt), Mask --> shl X, ShAmt
2065     if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) &&
2066         (~(*Mask)).lshr(*ShAmt).isZero())
2067       return Op0;
2068 
2069     // If all bits in the inverted and shifted mask are clear:
2070     // and (lshr X, ShAmt), Mask --> lshr X, ShAmt
2071     if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) &&
2072         (~(*Mask)).shl(*ShAmt).isZero())
2073       return Op0;
2074   }
2075 
2076   // and 2^x-1, 2^C --> 0 where x <= C.
2077   const APInt *PowerC;
2078   Value *Shift;
2079   if (match(Op1, m_Power2(PowerC)) &&
2080       match(Op0, m_Add(m_Value(Shift), m_AllOnes())) &&
2081       isKnownToBeAPowerOfTwo(Shift, Q.DL, /*OrZero*/ false, Q.AC, Q.CxtI,
2082                              Q.DT)) {
2083     KnownBits Known = computeKnownBits(Shift, Q);
2084     // Use getActiveBits() to make use of the additional power of two knowledge
2085     if (PowerC->getActiveBits() >= Known.getMaxValue().getActiveBits())
2086       return ConstantInt::getNullValue(Op1->getType());
2087   }
2088 
2089   if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true))
2090     return V;
2091 
2092   // Try some generic simplifications for associative operations.
2093   if (Value *V =
2094           simplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, MaxRecurse))
2095     return V;
2096 
2097   // And distributes over Or.  Try some generic simplifications based on this.
2098   if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1,
2099                                         Instruction::Or, Q, MaxRecurse))
2100     return V;
2101 
2102   // And distributes over Xor.  Try some generic simplifications based on this.
2103   if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1,
2104                                         Instruction::Xor, Q, MaxRecurse))
2105     return V;
2106 
2107   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) {
2108     if (Op0->getType()->isIntOrIntVectorTy(1)) {
2109       // A & (A && B) -> A && B
2110       if (match(Op1, m_Select(m_Specific(Op0), m_Value(), m_Zero())))
2111         return Op1;
2112       else if (match(Op0, m_Select(m_Specific(Op1), m_Value(), m_Zero())))
2113         return Op0;
2114     }
2115     // If the operation is with the result of a select instruction, check
2116     // whether operating on either branch of the select always yields the same
2117     // value.
2118     if (Value *V =
2119             threadBinOpOverSelect(Instruction::And, Op0, Op1, Q, MaxRecurse))
2120       return V;
2121   }
2122 
2123   // If the operation is with the result of a phi instruction, check whether
2124   // operating on all incoming values of the phi always yields the same value.
2125   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
2126     if (Value *V =
2127             threadBinOpOverPHI(Instruction::And, Op0, Op1, Q, MaxRecurse))
2128       return V;
2129 
2130   // Assuming the effective width of Y is not larger than A, i.e. all bits
2131   // from X and Y are disjoint in (X << A) | Y,
2132   // if the mask of this AND op covers all bits of X or Y, while it covers
2133   // no bits from the other, we can bypass this AND op. E.g.,
2134   // ((X << A) | Y) & Mask -> Y,
2135   //     if Mask = ((1 << effective_width_of(Y)) - 1)
2136   // ((X << A) | Y) & Mask -> X << A,
2137   //     if Mask = ((1 << effective_width_of(X)) - 1) << A
2138   // SimplifyDemandedBits in InstCombine can optimize the general case.
2139   // This pattern aims to help other passes for a common case.
2140   Value *XShifted;
2141   if (Q.IIQ.UseInstrInfo && match(Op1, m_APInt(Mask)) &&
2142       match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)),
2143                                      m_Value(XShifted)),
2144                         m_Value(Y)))) {
2145     const unsigned Width = Op0->getType()->getScalarSizeInBits();
2146     const unsigned ShftCnt = ShAmt->getLimitedValue(Width);
2147     const KnownBits YKnown = computeKnownBits(Y, Q);
2148     const unsigned EffWidthY = YKnown.countMaxActiveBits();
2149     if (EffWidthY <= ShftCnt) {
2150       const KnownBits XKnown = computeKnownBits(X, Q);
2151       const unsigned EffWidthX = XKnown.countMaxActiveBits();
2152       const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY);
2153       const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt;
2154       // If the mask is extracting all bits from X or Y as is, we can skip
2155       // this AND op.
2156       if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask))
2157         return Y;
2158       if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask))
2159         return XShifted;
2160     }
2161   }
2162 
2163   // ((X | Y) ^ X ) & ((X | Y) ^ Y) --> 0
2164   // ((X | Y) ^ Y ) & ((X | Y) ^ X) --> 0
2165   BinaryOperator *Or;
2166   if (match(Op0, m_c_Xor(m_Value(X),
2167                          m_CombineAnd(m_BinOp(Or),
2168                                       m_c_Or(m_Deferred(X), m_Value(Y))))) &&
2169       match(Op1, m_c_Xor(m_Specific(Or), m_Specific(Y))))
2170     return Constant::getNullValue(Op0->getType());
2171 
2172   const APInt *C1;
2173   Value *A;
2174   // (A ^ C) & (A ^ ~C) -> 0
2175   if (match(Op0, m_Xor(m_Value(A), m_APInt(C1))) &&
2176       match(Op1, m_Xor(m_Specific(A), m_SpecificInt(~*C1))))
2177     return Constant::getNullValue(Op0->getType());
2178 
2179   if (Op0->getType()->isIntOrIntVectorTy(1)) {
2180     if (std::optional<bool> Implied = isImpliedCondition(Op0, Op1, Q.DL)) {
2181       // If Op0 is true implies Op1 is true, then Op0 is a subset of Op1.
2182       if (*Implied == true)
2183         return Op0;
2184       // If Op0 is true implies Op1 is false, then they are not true together.
2185       if (*Implied == false)
2186         return ConstantInt::getFalse(Op0->getType());
2187     }
2188     if (std::optional<bool> Implied = isImpliedCondition(Op1, Op0, Q.DL)) {
2189       // If Op1 is true implies Op0 is true, then Op1 is a subset of Op0.
2190       if (*Implied)
2191         return Op1;
2192       // If Op1 is true implies Op0 is false, then they are not true together.
2193       if (!*Implied)
2194         return ConstantInt::getFalse(Op1->getType());
2195     }
2196   }
2197 
2198   if (Value *V = simplifyByDomEq(Instruction::And, Op0, Op1, Q, MaxRecurse))
2199     return V;
2200 
2201   return nullptr;
2202 }
2203 
simplifyAndInst(Value * Op0,Value * Op1,const SimplifyQuery & Q)2204 Value *llvm::simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
2205   return ::simplifyAndInst(Op0, Op1, Q, RecursionLimit);
2206 }
2207 
2208 // TODO: Many of these folds could use LogicalAnd/LogicalOr.
simplifyOrLogic(Value * X,Value * Y)2209 static Value *simplifyOrLogic(Value *X, Value *Y) {
2210   assert(X->getType() == Y->getType() && "Expected same type for 'or' ops");
2211   Type *Ty = X->getType();
2212 
2213   // X | ~X --> -1
2214   if (match(Y, m_Not(m_Specific(X))))
2215     return ConstantInt::getAllOnesValue(Ty);
2216 
2217   // X | ~(X & ?) = -1
2218   if (match(Y, m_Not(m_c_And(m_Specific(X), m_Value()))))
2219     return ConstantInt::getAllOnesValue(Ty);
2220 
2221   // X | (X & ?) --> X
2222   if (match(Y, m_c_And(m_Specific(X), m_Value())))
2223     return X;
2224 
2225   Value *A, *B;
2226 
2227   // (A ^ B) | (A | B) --> A | B
2228   // (A ^ B) | (B | A) --> B | A
2229   if (match(X, m_Xor(m_Value(A), m_Value(B))) &&
2230       match(Y, m_c_Or(m_Specific(A), m_Specific(B))))
2231     return Y;
2232 
2233   // ~(A ^ B) | (A | B) --> -1
2234   // ~(A ^ B) | (B | A) --> -1
2235   if (match(X, m_Not(m_Xor(m_Value(A), m_Value(B)))) &&
2236       match(Y, m_c_Or(m_Specific(A), m_Specific(B))))
2237     return ConstantInt::getAllOnesValue(Ty);
2238 
2239   // (A & ~B) | (A ^ B) --> A ^ B
2240   // (~B & A) | (A ^ B) --> A ^ B
2241   // (A & ~B) | (B ^ A) --> B ^ A
2242   // (~B & A) | (B ^ A) --> B ^ A
2243   if (match(X, m_c_And(m_Value(A), m_Not(m_Value(B)))) &&
2244       match(Y, m_c_Xor(m_Specific(A), m_Specific(B))))
2245     return Y;
2246 
2247   // (~A ^ B) | (A & B) --> ~A ^ B
2248   // (B ^ ~A) | (A & B) --> B ^ ~A
2249   // (~A ^ B) | (B & A) --> ~A ^ B
2250   // (B ^ ~A) | (B & A) --> B ^ ~A
2251   if (match(X, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) &&
2252       match(Y, m_c_And(m_Specific(A), m_Specific(B))))
2253     return X;
2254 
2255   // (~A | B) | (A ^ B) --> -1
2256   // (~A | B) | (B ^ A) --> -1
2257   // (B | ~A) | (A ^ B) --> -1
2258   // (B | ~A) | (B ^ A) --> -1
2259   if (match(X, m_c_Or(m_Not(m_Value(A)), m_Value(B))) &&
2260       match(Y, m_c_Xor(m_Specific(A), m_Specific(B))))
2261     return ConstantInt::getAllOnesValue(Ty);
2262 
2263   // (~A & B) | ~(A | B) --> ~A
2264   // (~A & B) | ~(B | A) --> ~A
2265   // (B & ~A) | ~(A | B) --> ~A
2266   // (B & ~A) | ~(B | A) --> ~A
2267   Value *NotA;
2268   if (match(X, m_c_And(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))),
2269                        m_Value(B))) &&
2270       match(Y, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
2271     return NotA;
2272   // The same is true of Logical And
2273   // TODO: This could share the logic of the version above if there was a
2274   // version of LogicalAnd that allowed more than just i1 types.
2275   if (match(X, m_c_LogicalAnd(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))),
2276                               m_Value(B))) &&
2277       match(Y, m_Not(m_c_LogicalOr(m_Specific(A), m_Specific(B)))))
2278     return NotA;
2279 
2280   // ~(A ^ B) | (A & B) --> ~(A ^ B)
2281   // ~(A ^ B) | (B & A) --> ~(A ^ B)
2282   Value *NotAB;
2283   if (match(X, m_CombineAnd(m_Not(m_Xor(m_Value(A), m_Value(B))),
2284                             m_Value(NotAB))) &&
2285       match(Y, m_c_And(m_Specific(A), m_Specific(B))))
2286     return NotAB;
2287 
2288   // ~(A & B) | (A ^ B) --> ~(A & B)
2289   // ~(A & B) | (B ^ A) --> ~(A & B)
2290   if (match(X, m_CombineAnd(m_Not(m_And(m_Value(A), m_Value(B))),
2291                             m_Value(NotAB))) &&
2292       match(Y, m_c_Xor(m_Specific(A), m_Specific(B))))
2293     return NotAB;
2294 
2295   return nullptr;
2296 }
2297 
2298 /// Given operands for an Or, see if we can fold the result.
2299 /// If not, this returns null.
simplifyOrInst(Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)2300 static Value *simplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
2301                              unsigned MaxRecurse) {
2302   if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q))
2303     return C;
2304 
2305   // X | poison -> poison
2306   if (isa<PoisonValue>(Op1))
2307     return Op1;
2308 
2309   // X | undef -> -1
2310   // X | -1 = -1
2311   // Do not return Op1 because it may contain undef elements if it's a vector.
2312   if (Q.isUndefValue(Op1) || match(Op1, m_AllOnes()))
2313     return Constant::getAllOnesValue(Op0->getType());
2314 
2315   // X | X = X
2316   // X | 0 = X
2317   if (Op0 == Op1 || match(Op1, m_Zero()))
2318     return Op0;
2319 
2320   if (Value *R = simplifyOrLogic(Op0, Op1))
2321     return R;
2322   if (Value *R = simplifyOrLogic(Op1, Op0))
2323     return R;
2324 
2325   if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Or))
2326     return V;
2327 
2328   // Rotated -1 is still -1:
2329   // (-1 << X) | (-1 >> (C - X)) --> -1
2330   // (-1 >> X) | (-1 << (C - X)) --> -1
2331   // ...with C <= bitwidth (and commuted variants).
2332   Value *X, *Y;
2333   if ((match(Op0, m_Shl(m_AllOnes(), m_Value(X))) &&
2334        match(Op1, m_LShr(m_AllOnes(), m_Value(Y)))) ||
2335       (match(Op1, m_Shl(m_AllOnes(), m_Value(X))) &&
2336        match(Op0, m_LShr(m_AllOnes(), m_Value(Y))))) {
2337     const APInt *C;
2338     if ((match(X, m_Sub(m_APInt(C), m_Specific(Y))) ||
2339          match(Y, m_Sub(m_APInt(C), m_Specific(X)))) &&
2340         C->ule(X->getType()->getScalarSizeInBits())) {
2341       return ConstantInt::getAllOnesValue(X->getType());
2342     }
2343   }
2344 
2345   // A funnel shift (rotate) can be decomposed into simpler shifts. See if we
2346   // are mixing in another shift that is redundant with the funnel shift.
2347 
2348   // (fshl X, ?, Y) | (shl X, Y) --> fshl X, ?, Y
2349   // (shl X, Y) | (fshl X, ?, Y) --> fshl X, ?, Y
2350   if (match(Op0,
2351             m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(Y))) &&
2352       match(Op1, m_Shl(m_Specific(X), m_Specific(Y))))
2353     return Op0;
2354   if (match(Op1,
2355             m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(Y))) &&
2356       match(Op0, m_Shl(m_Specific(X), m_Specific(Y))))
2357     return Op1;
2358 
2359   // (fshr ?, X, Y) | (lshr X, Y) --> fshr ?, X, Y
2360   // (lshr X, Y) | (fshr ?, X, Y) --> fshr ?, X, Y
2361   if (match(Op0,
2362             m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(Y))) &&
2363       match(Op1, m_LShr(m_Specific(X), m_Specific(Y))))
2364     return Op0;
2365   if (match(Op1,
2366             m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(Y))) &&
2367       match(Op0, m_LShr(m_Specific(X), m_Specific(Y))))
2368     return Op1;
2369 
2370   if (Value *V =
2371           simplifyAndOrWithICmpEq(Instruction::Or, Op0, Op1, Q, MaxRecurse))
2372     return V;
2373   if (Value *V =
2374           simplifyAndOrWithICmpEq(Instruction::Or, Op1, Op0, Q, MaxRecurse))
2375     return V;
2376 
2377   if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false))
2378     return V;
2379 
2380   // If we have a multiplication overflow check that is being 'and'ed with a
2381   // check that one of the multipliers is not zero, we can omit the 'and', and
2382   // only keep the overflow check.
2383   if (isCheckForZeroAndMulWithOverflow(Op0, Op1, false))
2384     return Op1;
2385   if (isCheckForZeroAndMulWithOverflow(Op1, Op0, false))
2386     return Op0;
2387 
2388   // Try some generic simplifications for associative operations.
2389   if (Value *V =
2390           simplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, MaxRecurse))
2391     return V;
2392 
2393   // Or distributes over And.  Try some generic simplifications based on this.
2394   if (Value *V = expandCommutativeBinOp(Instruction::Or, Op0, Op1,
2395                                         Instruction::And, Q, MaxRecurse))
2396     return V;
2397 
2398   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) {
2399     if (Op0->getType()->isIntOrIntVectorTy(1)) {
2400       // A | (A || B) -> A || B
2401       if (match(Op1, m_Select(m_Specific(Op0), m_One(), m_Value())))
2402         return Op1;
2403       else if (match(Op0, m_Select(m_Specific(Op1), m_One(), m_Value())))
2404         return Op0;
2405     }
2406     // If the operation is with the result of a select instruction, check
2407     // whether operating on either branch of the select always yields the same
2408     // value.
2409     if (Value *V =
2410             threadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, MaxRecurse))
2411       return V;
2412   }
2413 
2414   // (A & C1)|(B & C2)
2415   Value *A, *B;
2416   const APInt *C1, *C2;
2417   if (match(Op0, m_And(m_Value(A), m_APInt(C1))) &&
2418       match(Op1, m_And(m_Value(B), m_APInt(C2)))) {
2419     if (*C1 == ~*C2) {
2420       // (A & C1)|(B & C2)
2421       // If we have: ((V + N) & C1) | (V & C2)
2422       // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2423       // replace with V+N.
2424       Value *N;
2425       if (C2->isMask() && // C2 == 0+1+
2426           match(A, m_c_Add(m_Specific(B), m_Value(N)))) {
2427         // Add commutes, try both ways.
2428         if (MaskedValueIsZero(N, *C2, Q))
2429           return A;
2430       }
2431       // Or commutes, try both ways.
2432       if (C1->isMask() && match(B, m_c_Add(m_Specific(A), m_Value(N)))) {
2433         // Add commutes, try both ways.
2434         if (MaskedValueIsZero(N, *C1, Q))
2435           return B;
2436       }
2437     }
2438   }
2439 
2440   // If the operation is with the result of a phi instruction, check whether
2441   // operating on all incoming values of the phi always yields the same value.
2442   if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
2443     if (Value *V = threadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
2444       return V;
2445 
2446   // (A ^ C) | (A ^ ~C) -> -1, i.e. all bits set to one.
2447   if (match(Op0, m_Xor(m_Value(A), m_APInt(C1))) &&
2448       match(Op1, m_Xor(m_Specific(A), m_SpecificInt(~*C1))))
2449     return Constant::getAllOnesValue(Op0->getType());
2450 
2451   if (Op0->getType()->isIntOrIntVectorTy(1)) {
2452     if (std::optional<bool> Implied =
2453             isImpliedCondition(Op0, Op1, Q.DL, false)) {
2454       // If Op0 is false implies Op1 is false, then Op1 is a subset of Op0.
2455       if (*Implied == false)
2456         return Op0;
2457       // If Op0 is false implies Op1 is true, then at least one is always true.
2458       if (*Implied == true)
2459         return ConstantInt::getTrue(Op0->getType());
2460     }
2461     if (std::optional<bool> Implied =
2462             isImpliedCondition(Op1, Op0, Q.DL, false)) {
2463       // If Op1 is false implies Op0 is false, then Op0 is a subset of Op1.
2464       if (*Implied == false)
2465         return Op1;
2466       // If Op1 is false implies Op0 is true, then at least one is always true.
2467       if (*Implied == true)
2468         return ConstantInt::getTrue(Op1->getType());
2469     }
2470   }
2471 
2472   if (Value *V = simplifyByDomEq(Instruction::Or, Op0, Op1, Q, MaxRecurse))
2473     return V;
2474 
2475   return nullptr;
2476 }
2477 
simplifyOrInst(Value * Op0,Value * Op1,const SimplifyQuery & Q)2478 Value *llvm::simplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
2479   return ::simplifyOrInst(Op0, Op1, Q, RecursionLimit);
2480 }
2481 
2482 /// Given operands for a Xor, see if we can fold the result.
2483 /// If not, this returns null.
simplifyXorInst(Value * Op0,Value * Op1,const SimplifyQuery & Q,unsigned MaxRecurse)2484 static Value *simplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
2485                               unsigned MaxRecurse) {
2486   if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q))
2487     return C;
2488 
2489   // X ^ poison -> poison
2490   if (isa<PoisonValue>(Op1))
2491     return Op1;
2492 
2493   // A ^ undef -> undef
2494   if (Q.isUndefValue(Op1))
2495     return Op1;
2496 
2497   // A ^ 0 = A
2498   if (match(Op1, m_Zero()))
2499     return Op0;
2500 
2501   // A ^ A = 0
2502   if (Op0 == Op1)
2503     return Constant::getNullValue(Op0->getType());
2504 
2505   // A ^ ~A  =  ~A ^ A  =  -1
2506   if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0))))
2507     return Constant::getAllOnesValue(Op0->getType());
2508 
2509   auto foldAndOrNot = [](Value *X, Value *Y) -> Value * {
2510     Value *A, *B;
2511     // (~A & B) ^ (A | B) --> A -- There are 8 commuted variants.
2512     if (match(X, m_c_And(m_Not(m_Value(A)), m_Value(B))) &&
2513         match(Y, m_c_Or(m_Specific(A), m_Specific(B))))
2514       return A;
2515 
2516     // (~A | B) ^ (A & B) --> ~A -- There are 8 commuted variants.
2517     // The 'not' op must contain a complete -1 operand (no undef elements for
2518     // vector) for the transform to be safe.
2519     Value *NotA;
2520     if (match(X, m_c_Or(m_CombineAnd(m_Not(m_Value(A)), m_Value(NotA)),
2521                         m_Value(B))) &&
2522         match(Y, m_c_And(m_Specific(A), m_Specific(B))))
2523       return NotA;
2524 
2525     return nullptr;
2526   };
2527   if (Value *R = foldAndOrNot(Op0, Op1))
2528     return R;
2529   if (Value *R = foldAndOrNot(Op1, Op0))
2530     return R;
2531 
2532   if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor))
2533     return V;
2534 
2535   // Try some generic simplifications for associative operations.
2536   if (Value *V =
2537           simplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, MaxRecurse))
2538     return V;
2539 
2540   // Threading Xor over selects and phi nodes is pointless, so don't bother.
2541   // Threading over the select in "A ^ select(cond, B, C)" means evaluating
2542   // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
2543   // only if B and C are equal.  If B and C are equal then (since we assume
2544   // that operands have already been simplified) "select(cond, B, C)" should
2545   // have been simplified to the common value of B and C already.  Analysing
2546   // "A^B" and "A^C" thus gains nothing, but costs compile time.  Similarly
2547   // for threading over phi nodes.
2548 
2549   if (Value *V = simplifyByDomEq(Instruction::Xor, Op0, Op1, Q, MaxRecurse))
2550     return V;
2551 
2552   // (xor (sub nuw C_Mask, X), C_Mask) -> X
2553   {
2554     Value *X;
2555     if (match(Op0, m_NUWSub(m_Specific(Op1), m_Value(X))) &&
2556         match(Op1, m_LowBitMask()))
2557       return X;
2558   }
2559 
2560   return nullptr;
2561 }
2562 
simplifyXorInst(Value * Op0,Value * Op1,const SimplifyQuery & Q)2563 Value *llvm::simplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
2564   return ::simplifyXorInst(Op0, Op1, Q, RecursionLimit);
2565 }
2566 
getCompareTy(Value * Op)2567 static Type *getCompareTy(Value *Op) {
2568   return CmpInst::makeCmpResultType(Op->getType());
2569 }
2570 
2571 /// Rummage around inside V looking for something equivalent to the comparison
2572 /// "LHS Pred RHS". Return such a value if found, otherwise return null.
2573 /// Helper function for analyzing max/min idioms.
extractEquivalentCondition(Value * V,CmpPredicate Pred,Value * LHS,Value * RHS)2574 static Value *extractEquivalentCondition(Value *V, CmpPredicate Pred,
2575                                          Value *LHS, Value *RHS) {
2576   SelectInst *SI = dyn_cast<SelectInst>(V);
2577   if (!SI)
2578     return nullptr;
2579   CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
2580   if (!Cmp)
2581     return nullptr;
2582   Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
2583   if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
2584     return Cmp;
2585   if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
2586       LHS == CmpRHS && RHS == CmpLHS)
2587     return Cmp;
2588   return nullptr;
2589 }
2590 
2591 /// Return true if the underlying object (storage) must be disjoint from
2592 /// storage returned by any noalias return call.
isAllocDisjoint(const Value * V)2593 static bool isAllocDisjoint(const Value *V) {
2594   // For allocas, we consider only static ones (dynamic
2595   // allocas might be transformed into calls to malloc not simultaneously
2596   // live with the compared-to allocation). For globals, we exclude symbols
2597   // that might be resolve lazily to symbols in another dynamically-loaded
2598   // library (and, thus, could be malloc'ed by the implementation).
2599   if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
2600     return AI->isStaticAlloca();
2601   if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
2602     return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() ||
2603             GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) &&
2604            !GV->isThreadLocal();
2605   if (const Argument *A = dyn_cast<Argument>(V))
2606     return A->hasByValAttr();
2607   return false;
2608 }
2609 
2610 /// Return true if V1 and V2 are each the base of some distict storage region
2611 /// [V, object_size(V)] which do not overlap.  Note that zero sized regions
2612 /// *are* possible, and that zero sized regions do not overlap with any other.
haveNonOverlappingStorage(const Value * V1,const Value * V2)2613 static bool haveNonOverlappingStorage(const Value *V1, const Value *V2) {
2614   // Global variables always exist, so they always exist during the lifetime
2615   // of each other and all allocas.  Global variables themselves usually have
2616   // non-overlapping storage, but since their addresses are constants, the
2617   // case involving two globals does not reach here and is instead handled in
2618   // constant folding.
2619   //
2620   // Two different allocas usually have different addresses...
2621   //
2622   // However, if there's an @llvm.stackrestore dynamically in between two
2623   // allocas, they may have the same address. It's tempting to reduce the
2624   // scope of the problem by only looking at *static* allocas here. That would
2625   // cover the majority of allocas while significantly reducing the likelihood
2626   // of having an @llvm.stackrestore pop up in the middle. However, it's not
2627   // actually impossible for an @llvm.stackrestore to pop up in the middle of
2628   // an entry block. Also, if we have a block that's not attached to a
2629   // function, we can't tell if it's "static" under the current definition.
2630   // Theoretically, this problem could be fixed by creating a new kind of
2631   // instruction kind specifically for static allocas. Such a new instruction
2632   // could be required to be at the top of the entry block, thus preventing it
2633   // from being subject to a @llvm.stackrestore. Instcombine could even
2634   // convert regular allocas into these special allocas. It'd be nifty.
2635   // However, until then, this problem remains open.
2636   //
2637   // So, we'll assume that two non-empty allocas have different addresses
2638   // for now.
2639   auto isByValArg = [](const Value *V) {
2640     const Argument *A = dyn_cast<Argument>(V);
2641     return A && A->hasByValAttr();
2642   };
2643 
2644   // Byval args are backed by store which does not overlap with each other,
2645   // allocas, or globals.
2646   if (isByValArg(V1))
2647     return isa<AllocaInst>(V2) || isa<GlobalVariable>(V2) || isByValArg(V2);
2648   if (isByValArg(V2))
2649     return isa<AllocaInst>(V1) || isa<GlobalVariable>(V1) || isByValArg(V1);
2650 
2651   return isa<AllocaInst>(V1) &&
2652          (isa<AllocaInst>(V2) || isa<GlobalVariable>(V2));
2653 }
2654 
2655 // A significant optimization not implemented here is assuming that alloca
2656 // addresses are not equal to incoming argument values. They don't *alias*,
2657 // as we say, but that doesn't mean they aren't equal, so we take a
2658 // conservative approach.
2659 //
2660 // This is inspired in part by C++11 5.10p1:
2661 //   "Two pointers of the same type compare equal if and only if they are both
2662 //    null, both point to the same function, or both represent the same
2663 //    address."
2664 //
2665 // This is pretty permissive.
2666 //
2667 // It's also partly due to C11 6.5.9p6:
2668 //   "Two pointers compare equal if and only if both are null pointers, both are
2669 //    pointers to the same object (including a pointer to an object and a
2670 //    subobject at its beginning) or function, both are pointers to one past the
2671 //    last element of the same array object, or one is a pointer to one past the
2672 //    end of one array object and the other is a pointer to the start of a
2673 //    different array object that happens to immediately follow the first array
2674 //    object in the address space.)
2675 //
2676 // C11's version is more restrictive, however there's no reason why an argument
2677 // couldn't be a one-past-the-end value for a stack object in the caller and be
2678 // equal to the beginning of a stack object in the callee.
2679 //
2680 // If the C and C++ standards are ever made sufficiently restrictive in this
2681 // area, it may be possible to update LLVM's semantics accordingly and reinstate
2682 // this optimization.
computePointerICmp(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q)2683 static Constant *computePointerICmp(CmpPredicate Pred, Value *LHS, Value *RHS,
2684                                     const SimplifyQuery &Q) {
2685   assert(LHS->getType() == RHS->getType() && "Must have same types");
2686   const DataLayout &DL = Q.DL;
2687   const TargetLibraryInfo *TLI = Q.TLI;
2688 
2689   // We fold equality and unsigned predicates on pointer comparisons, but forbid
2690   // signed predicates since a GEP with inbounds could cross the sign boundary.
2691   if (CmpInst::isSigned(Pred))
2692     return nullptr;
2693 
2694   // We have to switch to a signed predicate to handle negative indices from
2695   // the base pointer.
2696   Pred = ICmpInst::getSignedPredicate(Pred);
2697 
2698   // Strip off any constant offsets so that we can reason about them.
2699   // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
2700   // here and compare base addresses like AliasAnalysis does, however there are
2701   // numerous hazards. AliasAnalysis and its utilities rely on special rules
2702   // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
2703   // doesn't need to guarantee pointer inequality when it says NoAlias.
2704 
2705   // Even if an non-inbounds GEP occurs along the path we can still optimize
2706   // equality comparisons concerning the result.
2707   bool AllowNonInbounds = ICmpInst::isEquality(Pred);
2708   unsigned IndexSize = DL.getIndexTypeSizeInBits(LHS->getType());
2709   APInt LHSOffset(IndexSize, 0), RHSOffset(IndexSize, 0);
2710   LHS = LHS->stripAndAccumulateConstantOffsets(DL, LHSOffset, AllowNonInbounds);
2711   RHS = RHS->stripAndAccumulateConstantOffsets(DL, RHSOffset, AllowNonInbounds);
2712 
2713   // If LHS and RHS are related via constant offsets to the same base
2714   // value, we can replace it with an icmp which just compares the offsets.
2715   if (LHS == RHS)
2716     return ConstantInt::get(getCompareTy(LHS),
2717                             ICmpInst::compare(LHSOffset, RHSOffset, Pred));
2718 
2719   // Various optimizations for (in)equality comparisons.
2720   if (ICmpInst::isEquality(Pred)) {
2721     // Different non-empty allocations that exist at the same time have
2722     // different addresses (if the program can tell). If the offsets are
2723     // within the bounds of their allocations (and not one-past-the-end!
2724     // so we can't use inbounds!), and their allocations aren't the same,
2725     // the pointers are not equal.
2726     if (haveNonOverlappingStorage(LHS, RHS)) {
2727       uint64_t LHSSize, RHSSize;
2728       ObjectSizeOpts Opts;
2729       Opts.EvalMode = ObjectSizeOpts::Mode::Min;
2730       auto *F = [](Value *V) -> Function * {
2731         if (auto *I = dyn_cast<Instruction>(V))
2732           return I->getFunction();
2733         if (auto *A = dyn_cast<Argument>(V))
2734           return A->getParent();
2735         return nullptr;
2736       }(LHS);
2737       Opts.NullIsUnknownSize = F ? NullPointerIsDefined(F) : true;
2738       if (getObjectSize(LHS, LHSSize, DL, TLI, Opts) && LHSSize != 0 &&
2739           getObjectSize(RHS, RHSSize, DL, TLI, Opts) && RHSSize != 0) {
2740         APInt Dist = LHSOffset - RHSOffset;
2741         if (Dist.isNonNegative() ? Dist.ult(LHSSize) : (-Dist).ult(RHSSize))
2742           return ConstantInt::get(getCompareTy(LHS),
2743                                   !CmpInst::isTrueWhenEqual(Pred));
2744       }
2745     }
2746 
2747     // If one side of the equality comparison must come from a noalias call
2748     // (meaning a system memory allocation function), and the other side must
2749     // come from a pointer that cannot overlap with dynamically-allocated
2750     // memory within the lifetime of the current function (allocas, byval
2751     // arguments, globals), then determine the comparison result here.
2752     SmallVector<const Value *, 8> LHSUObjs, RHSUObjs;
2753     getUnderlyingObjects(LHS, LHSUObjs);
2754     getUnderlyingObjects(RHS, RHSUObjs);
2755 
2756     // Is the set of underlying objects all noalias calls?
2757     auto IsNAC = [](ArrayRef<const Value *> Objects) {
2758       return all_of(Objects, isNoAliasCall);
2759     };
2760 
2761     // Is the set of underlying objects all things which must be disjoint from
2762     // noalias calls.  We assume that indexing from such disjoint storage
2763     // into the heap is undefined, and thus offsets can be safely ignored.
2764     auto IsAllocDisjoint = [](ArrayRef<const Value *> Objects) {
2765       return all_of(Objects, ::isAllocDisjoint);
2766     };
2767 
2768     if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
2769         (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
2770       return ConstantInt::get(getCompareTy(LHS),
2771                               !CmpInst::isTrueWhenEqual(Pred));
2772 
2773     // Fold comparisons for non-escaping pointer even if the allocation call
2774     // cannot be elided. We cannot fold malloc comparison to null. Also, the
2775     // dynamic allocation call could be either of the operands.  Note that
2776     // the other operand can not be based on the alloc - if it were, then
2777     // the cmp itself would be a capture.
2778     Value *MI = nullptr;
2779     if (isAllocLikeFn(LHS, TLI) && llvm::isKnownNonZero(RHS, Q))
2780       MI = LHS;
2781     else if (isAllocLikeFn(RHS, TLI) && llvm::isKnownNonZero(LHS, Q))
2782       MI = RHS;
2783     if (MI) {
2784       // FIXME: This is incorrect, see PR54002. While we can assume that the
2785       // allocation is at an address that makes the comparison false, this
2786       // requires that *all* comparisons to that address be false, which
2787       // InstSimplify cannot guarantee.
2788       struct CustomCaptureTracker : public CaptureTracker {
2789         bool Captured = false;
2790         void tooManyUses() override { Captured = true; }
2791         Action captured(const Use *U, UseCaptureInfo CI) override {
2792           // TODO(captures): Use UseCaptureInfo.
2793           if (auto *ICmp = dyn_cast<ICmpInst>(U->getUser())) {
2794             // Comparison against value stored in global variable. Given the
2795             // pointer does not escape, its value cannot be guessed and stored
2796             // separately in a global variable.
2797             unsigned OtherIdx = 1 - U->getOperandNo();
2798             auto *LI = dyn_cast<LoadInst>(ICmp->getOperand(OtherIdx));
2799             if (LI && isa<GlobalVariable>(LI->getPointerOperand()))
2800               return Continue;
2801           }
2802 
2803           Captured = true;
2804           return Stop;
2805         }
2806       };
2807       CustomCaptureTracker Tracker;
2808       PointerMayBeCaptured(MI, &Tracker);
2809       if (!Tracker.Captured)
2810         return ConstantInt::get(getCompareTy(LHS),
2811                                 CmpInst::isFalseWhenEqual(Pred));
2812     }
2813   }
2814 
2815   // Otherwise, fail.
2816   return nullptr;
2817 }
2818 
2819 /// Fold an icmp when its operands have i1 scalar type.
simplifyICmpOfBools(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q)2820 static Value *simplifyICmpOfBools(CmpPredicate Pred, Value *LHS, Value *RHS,
2821                                   const SimplifyQuery &Q) {
2822   Type *ITy = getCompareTy(LHS); // The return type.
2823   Type *OpTy = LHS->getType();   // The operand type.
2824   if (!OpTy->isIntOrIntVectorTy(1))
2825     return nullptr;
2826 
2827   // A boolean compared to true/false can be reduced in 14 out of the 20
2828   // (10 predicates * 2 constants) possible combinations. The other
2829   // 6 cases require a 'not' of the LHS.
2830 
2831   auto ExtractNotLHS = [](Value *V) -> Value * {
2832     Value *X;
2833     if (match(V, m_Not(m_Value(X))))
2834       return X;
2835     return nullptr;
2836   };
2837 
2838   if (match(RHS, m_Zero())) {
2839     switch (Pred) {
2840     case CmpInst::ICMP_NE:  // X !=  0 -> X
2841     case CmpInst::ICMP_UGT: // X >u  0 -> X
2842     case CmpInst::ICMP_SLT: // X <s  0 -> X
2843       return LHS;
2844 
2845     case CmpInst::ICMP_EQ:  // not(X) ==  0 -> X != 0 -> X
2846     case CmpInst::ICMP_ULE: // not(X) <=u 0 -> X >u 0 -> X
2847     case CmpInst::ICMP_SGE: // not(X) >=s 0 -> X <s 0 -> X
2848       if (Value *X = ExtractNotLHS(LHS))
2849         return X;
2850       break;
2851 
2852     case CmpInst::ICMP_ULT: // X <u  0 -> false
2853     case CmpInst::ICMP_SGT: // X >s  0 -> false
2854       return getFalse(ITy);
2855 
2856     case CmpInst::ICMP_UGE: // X >=u 0 -> true
2857     case CmpInst::ICMP_SLE: // X <=s 0 -> true
2858       return getTrue(ITy);
2859 
2860     default:
2861       break;
2862     }
2863   } else if (match(RHS, m_One())) {
2864     switch (Pred) {
2865     case CmpInst::ICMP_EQ:  // X ==   1 -> X
2866     case CmpInst::ICMP_UGE: // X >=u  1 -> X
2867     case CmpInst::ICMP_SLE: // X <=s -1 -> X
2868       return LHS;
2869 
2870     case CmpInst::ICMP_NE:  // not(X) !=  1 -> X ==   1 -> X
2871     case CmpInst::ICMP_ULT: // not(X) <=u 1 -> X >=u  1 -> X
2872     case CmpInst::ICMP_SGT: // not(X) >s  1 -> X <=s -1 -> X
2873       if (Value *X = ExtractNotLHS(LHS))
2874         return X;
2875       break;
2876 
2877     case CmpInst::ICMP_UGT: // X >u   1 -> false
2878     case CmpInst::ICMP_SLT: // X <s  -1 -> false
2879       return getFalse(ITy);
2880 
2881     case CmpInst::ICMP_ULE: // X <=u  1 -> true
2882     case CmpInst::ICMP_SGE: // X >=s -1 -> true
2883       return getTrue(ITy);
2884 
2885     default:
2886       break;
2887     }
2888   }
2889 
2890   switch (Pred) {
2891   default:
2892     break;
2893   case ICmpInst::ICMP_UGE:
2894     if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false))
2895       return getTrue(ITy);
2896     break;
2897   case ICmpInst::ICMP_SGE:
2898     /// For signed comparison, the values for an i1 are 0 and -1
2899     /// respectively. This maps into a truth table of:
2900     /// LHS | RHS | LHS >=s RHS   | LHS implies RHS
2901     ///  0  |  0  |  1 (0 >= 0)   |  1
2902     ///  0  |  1  |  1 (0 >= -1)  |  1
2903     ///  1  |  0  |  0 (-1 >= 0)  |  0
2904     ///  1  |  1  |  1 (-1 >= -1) |  1
2905     if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false))
2906       return getTrue(ITy);
2907     break;
2908   case ICmpInst::ICMP_ULE:
2909     if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false))
2910       return getTrue(ITy);
2911     break;
2912   case ICmpInst::ICMP_SLE:
2913     /// SLE follows the same logic as SGE with the LHS and RHS swapped.
2914     if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false))
2915       return getTrue(ITy);
2916     break;
2917   }
2918 
2919   return nullptr;
2920 }
2921 
2922 /// Try hard to fold icmp with zero RHS because this is a common case.
simplifyICmpWithZero(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q)2923 static Value *simplifyICmpWithZero(CmpPredicate Pred, Value *LHS, Value *RHS,
2924                                    const SimplifyQuery &Q) {
2925   if (!match(RHS, m_Zero()))
2926     return nullptr;
2927 
2928   Type *ITy = getCompareTy(LHS); // The return type.
2929   switch (Pred) {
2930   default:
2931     llvm_unreachable("Unknown ICmp predicate!");
2932   case ICmpInst::ICMP_ULT:
2933     return getFalse(ITy);
2934   case ICmpInst::ICMP_UGE:
2935     return getTrue(ITy);
2936   case ICmpInst::ICMP_EQ:
2937   case ICmpInst::ICMP_ULE:
2938     if (isKnownNonZero(LHS, Q))
2939       return getFalse(ITy);
2940     break;
2941   case ICmpInst::ICMP_NE:
2942   case ICmpInst::ICMP_UGT:
2943     if (isKnownNonZero(LHS, Q))
2944       return getTrue(ITy);
2945     break;
2946   case ICmpInst::ICMP_SLT: {
2947     KnownBits LHSKnown = computeKnownBits(LHS, Q);
2948     if (LHSKnown.isNegative())
2949       return getTrue(ITy);
2950     if (LHSKnown.isNonNegative())
2951       return getFalse(ITy);
2952     break;
2953   }
2954   case ICmpInst::ICMP_SLE: {
2955     KnownBits LHSKnown = computeKnownBits(LHS, Q);
2956     if (LHSKnown.isNegative())
2957       return getTrue(ITy);
2958     if (LHSKnown.isNonNegative() && isKnownNonZero(LHS, Q))
2959       return getFalse(ITy);
2960     break;
2961   }
2962   case ICmpInst::ICMP_SGE: {
2963     KnownBits LHSKnown = computeKnownBits(LHS, Q);
2964     if (LHSKnown.isNegative())
2965       return getFalse(ITy);
2966     if (LHSKnown.isNonNegative())
2967       return getTrue(ITy);
2968     break;
2969   }
2970   case ICmpInst::ICMP_SGT: {
2971     KnownBits LHSKnown = computeKnownBits(LHS, Q);
2972     if (LHSKnown.isNegative())
2973       return getFalse(ITy);
2974     if (LHSKnown.isNonNegative() && isKnownNonZero(LHS, Q))
2975       return getTrue(ITy);
2976     break;
2977   }
2978   }
2979 
2980   return nullptr;
2981 }
2982 
simplifyICmpWithConstant(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q)2983 static Value *simplifyICmpWithConstant(CmpPredicate Pred, Value *LHS,
2984                                        Value *RHS, const SimplifyQuery &Q) {
2985   Type *ITy = getCompareTy(RHS); // The return type.
2986 
2987   Value *X;
2988   const APInt *C;
2989   if (!match(RHS, m_APIntAllowPoison(C)))
2990     return nullptr;
2991 
2992   // Sign-bit checks can be optimized to true/false after unsigned
2993   // floating-point casts:
2994   // icmp slt (bitcast (uitofp X)),  0 --> false
2995   // icmp sgt (bitcast (uitofp X)), -1 --> true
2996   if (match(LHS, m_ElementWiseBitCast(m_UIToFP(m_Value(X))))) {
2997     bool TrueIfSigned;
2998     if (isSignBitCheck(Pred, *C, TrueIfSigned))
2999       return ConstantInt::getBool(ITy, !TrueIfSigned);
3000   }
3001 
3002   // Rule out tautological comparisons (eg., ult 0 or uge 0).
3003   ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C);
3004   if (RHS_CR.isEmptySet())
3005     return ConstantInt::getFalse(ITy);
3006   if (RHS_CR.isFullSet())
3007     return ConstantInt::getTrue(ITy);
3008 
3009   ConstantRange LHS_CR =
3010       computeConstantRange(LHS, CmpInst::isSigned(Pred), Q.IIQ.UseInstrInfo);
3011   if (!LHS_CR.isFullSet()) {
3012     if (RHS_CR.contains(LHS_CR))
3013       return ConstantInt::getTrue(ITy);
3014     if (RHS_CR.inverse().contains(LHS_CR))
3015       return ConstantInt::getFalse(ITy);
3016   }
3017 
3018   // (mul nuw/nsw X, MulC) != C --> true  (if C is not a multiple of MulC)
3019   // (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC)
3020   const APInt *MulC;
3021   if (Q.IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) &&
3022       ((match(LHS, m_NUWMul(m_Value(), m_APIntAllowPoison(MulC))) &&
3023         *MulC != 0 && C->urem(*MulC) != 0) ||
3024        (match(LHS, m_NSWMul(m_Value(), m_APIntAllowPoison(MulC))) &&
3025         *MulC != 0 && C->srem(*MulC) != 0)))
3026     return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE);
3027 
3028   if (Pred == ICmpInst::ICMP_UGE && C->isOne() && isKnownNonZero(LHS, Q))
3029     return ConstantInt::getTrue(ITy);
3030 
3031   return nullptr;
3032 }
3033 
3034 enum class MonotonicType { GreaterEq, LowerEq };
3035 
3036 /// Get values V_i such that V uge V_i (GreaterEq) or V ule V_i (LowerEq).
getUnsignedMonotonicValues(SmallPtrSetImpl<Value * > & Res,Value * V,MonotonicType Type,const SimplifyQuery & Q,unsigned Depth=0)3037 static void getUnsignedMonotonicValues(SmallPtrSetImpl<Value *> &Res, Value *V,
3038                                        MonotonicType Type,
3039                                        const SimplifyQuery &Q,
3040                                        unsigned Depth = 0) {
3041   if (!Res.insert(V).second)
3042     return;
3043 
3044   // Can be increased if useful.
3045   if (++Depth > 1)
3046     return;
3047 
3048   auto *I = dyn_cast<Instruction>(V);
3049   if (!I)
3050     return;
3051 
3052   Value *X, *Y;
3053   if (Type == MonotonicType::GreaterEq) {
3054     if (match(I, m_Or(m_Value(X), m_Value(Y))) ||
3055         match(I, m_Intrinsic<Intrinsic::uadd_sat>(m_Value(X), m_Value(Y)))) {
3056       getUnsignedMonotonicValues(Res, X, Type, Q, Depth);
3057       getUnsignedMonotonicValues(Res, Y, Type, Q, Depth);
3058     }
3059     // X * Y >= X --> true
3060     if (match(I, m_NUWMul(m_Value(X), m_Value(Y)))) {
3061       if (isKnownNonZero(X, Q))
3062         getUnsignedMonotonicValues(Res, Y, Type, Q, Depth);
3063       if (isKnownNonZero(Y, Q))
3064         getUnsignedMonotonicValues(Res, X, Type, Q, Depth);
3065     }
3066   } else {
3067     assert(Type == MonotonicType::LowerEq);
3068     switch (I->getOpcode()) {
3069     case Instruction::And:
3070       getUnsignedMonotonicValues(Res, I->getOperand(0), Type, Q, Depth);
3071       getUnsignedMonotonicValues(Res, I->getOperand(1), Type, Q, Depth);
3072       break;
3073     case Instruction::URem:
3074     case Instruction::UDiv:
3075     case Instruction::LShr:
3076       getUnsignedMonotonicValues(Res, I->getOperand(0), Type, Q, Depth);
3077       break;
3078     case Instruction::Call:
3079       if (match(I, m_Intrinsic<Intrinsic::usub_sat>(m_Value(X))))
3080         getUnsignedMonotonicValues(Res, X, Type, Q, Depth);
3081       break;
3082     default:
3083       break;
3084     }
3085   }
3086 }
3087 
simplifyICmpUsingMonotonicValues(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q)3088 static Value *simplifyICmpUsingMonotonicValues(CmpPredicate Pred, Value *LHS,
3089                                                Value *RHS,
3090                                                const SimplifyQuery &Q) {
3091   if (Pred != ICmpInst::ICMP_UGE && Pred != ICmpInst::ICMP_ULT)
3092     return nullptr;
3093 
3094   // We have LHS uge GreaterValues and LowerValues uge RHS. If any of the
3095   // GreaterValues and LowerValues are the same, it follows that LHS uge RHS.
3096   SmallPtrSet<Value *, 4> GreaterValues;
3097   SmallPtrSet<Value *, 4> LowerValues;
3098   getUnsignedMonotonicValues(GreaterValues, LHS, MonotonicType::GreaterEq, Q);
3099   getUnsignedMonotonicValues(LowerValues, RHS, MonotonicType::LowerEq, Q);
3100   for (Value *GV : GreaterValues)
3101     if (LowerValues.contains(GV))
3102       return ConstantInt::getBool(getCompareTy(LHS),
3103                                   Pred == ICmpInst::ICMP_UGE);
3104   return nullptr;
3105 }
3106 
simplifyICmpWithBinOpOnLHS(CmpPredicate Pred,BinaryOperator * LBO,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)3107 static Value *simplifyICmpWithBinOpOnLHS(CmpPredicate Pred, BinaryOperator *LBO,
3108                                          Value *RHS, const SimplifyQuery &Q,
3109                                          unsigned MaxRecurse) {
3110   Type *ITy = getCompareTy(RHS); // The return type.
3111 
3112   Value *Y = nullptr;
3113   // icmp pred (or X, Y), X
3114   if (match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) {
3115     if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) {
3116       KnownBits RHSKnown = computeKnownBits(RHS, Q);
3117       KnownBits YKnown = computeKnownBits(Y, Q);
3118       if (RHSKnown.isNonNegative() && YKnown.isNegative())
3119         return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy);
3120       if (RHSKnown.isNegative() || YKnown.isNonNegative())
3121         return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy);
3122     }
3123   }
3124 
3125   // icmp pred (urem X, Y), Y
3126   if (match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
3127     switch (Pred) {
3128     default:
3129       break;
3130     case ICmpInst::ICMP_SGT:
3131     case ICmpInst::ICMP_SGE: {
3132       KnownBits Known = computeKnownBits(RHS, Q);
3133       if (!Known.isNonNegative())
3134         break;
3135       [[fallthrough]];
3136     }
3137     case ICmpInst::ICMP_EQ:
3138     case ICmpInst::ICMP_UGT:
3139     case ICmpInst::ICMP_UGE:
3140       return getFalse(ITy);
3141     case ICmpInst::ICMP_SLT:
3142     case ICmpInst::ICMP_SLE: {
3143       KnownBits Known = computeKnownBits(RHS, Q);
3144       if (!Known.isNonNegative())
3145         break;
3146       [[fallthrough]];
3147     }
3148     case ICmpInst::ICMP_NE:
3149     case ICmpInst::ICMP_ULT:
3150     case ICmpInst::ICMP_ULE:
3151       return getTrue(ITy);
3152     }
3153   }
3154 
3155   // If x is nonzero:
3156   // x >>u C <u  x --> true  for C != 0.
3157   // x >>u C !=  x --> true  for C != 0.
3158   // x >>u C >=u x --> false for C != 0.
3159   // x >>u C ==  x --> false for C != 0.
3160   // x udiv C <u  x --> true  for C != 1.
3161   // x udiv C !=  x --> true  for C != 1.
3162   // x udiv C >=u x --> false for C != 1.
3163   // x udiv C ==  x --> false for C != 1.
3164   // TODO: allow non-constant shift amount/divisor
3165   const APInt *C;
3166   if ((match(LBO, m_LShr(m_Specific(RHS), m_APInt(C))) && *C != 0) ||
3167       (match(LBO, m_UDiv(m_Specific(RHS), m_APInt(C))) && *C != 1)) {
3168     if (isKnownNonZero(RHS, Q)) {
3169       switch (Pred) {
3170       default:
3171         break;
3172       case ICmpInst::ICMP_EQ:
3173       case ICmpInst::ICMP_UGE:
3174       case ICmpInst::ICMP_UGT:
3175         return getFalse(ITy);
3176       case ICmpInst::ICMP_NE:
3177       case ICmpInst::ICMP_ULT:
3178       case ICmpInst::ICMP_ULE:
3179         return getTrue(ITy);
3180       }
3181     }
3182   }
3183 
3184   // (x*C1)/C2 <= x for C1 <= C2.
3185   // This holds even if the multiplication overflows: Assume that x != 0 and
3186   // arithmetic is modulo M. For overflow to occur we must have C1 >= M/x and
3187   // thus C2 >= M/x. It follows that (x*C1)/C2 <= (M-1)/C2 <= ((M-1)*x)/M < x.
3188   //
3189   // Additionally, either the multiplication and division might be represented
3190   // as shifts:
3191   // (x*C1)>>C2 <= x for C1 < 2**C2.
3192   // (x<<C1)/C2 <= x for 2**C1 < C2.
3193   const APInt *C1, *C2;
3194   if ((match(LBO, m_UDiv(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) &&
3195        C1->ule(*C2)) ||
3196       (match(LBO, m_LShr(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) &&
3197        C1->ule(APInt(C2->getBitWidth(), 1) << *C2)) ||
3198       (match(LBO, m_UDiv(m_Shl(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) &&
3199        (APInt(C1->getBitWidth(), 1) << *C1).ule(*C2))) {
3200     if (Pred == ICmpInst::ICMP_UGT)
3201       return getFalse(ITy);
3202     if (Pred == ICmpInst::ICMP_ULE)
3203       return getTrue(ITy);
3204   }
3205 
3206   // (sub C, X) == X, C is odd  --> false
3207   // (sub C, X) != X, C is odd  --> true
3208   if (match(LBO, m_Sub(m_APIntAllowPoison(C), m_Specific(RHS))) &&
3209       (*C & 1) == 1 && ICmpInst::isEquality(Pred))
3210     return (Pred == ICmpInst::ICMP_EQ) ? getFalse(ITy) : getTrue(ITy);
3211 
3212   return nullptr;
3213 }
3214 
3215 // If only one of the icmp's operands has NSW flags, try to prove that:
3216 //
3217 //   icmp slt (x + C1), (x +nsw C2)
3218 //
3219 // is equivalent to:
3220 //
3221 //   icmp slt C1, C2
3222 //
3223 // which is true if x + C2 has the NSW flags set and:
3224 // *) C1 < C2 && C1 >= 0, or
3225 // *) C2 < C1 && C1 <= 0.
3226 //
trySimplifyICmpWithAdds(CmpPredicate Pred,Value * LHS,Value * RHS,const InstrInfoQuery & IIQ)3227 static bool trySimplifyICmpWithAdds(CmpPredicate Pred, Value *LHS, Value *RHS,
3228                                     const InstrInfoQuery &IIQ) {
3229   // TODO: only support icmp slt for now.
3230   if (Pred != CmpInst::ICMP_SLT || !IIQ.UseInstrInfo)
3231     return false;
3232 
3233   // Canonicalize nsw add as RHS.
3234   if (!match(RHS, m_NSWAdd(m_Value(), m_Value())))
3235     std::swap(LHS, RHS);
3236   if (!match(RHS, m_NSWAdd(m_Value(), m_Value())))
3237     return false;
3238 
3239   Value *X;
3240   const APInt *C1, *C2;
3241   if (!match(LHS, m_Add(m_Value(X), m_APInt(C1))) ||
3242       !match(RHS, m_Add(m_Specific(X), m_APInt(C2))))
3243     return false;
3244 
3245   return (C1->slt(*C2) && C1->isNonNegative()) ||
3246          (C2->slt(*C1) && C1->isNonPositive());
3247 }
3248 
3249 /// TODO: A large part of this logic is duplicated in InstCombine's
3250 /// foldICmpBinOp(). We should be able to share that and avoid the code
3251 /// duplication.
simplifyICmpWithBinOp(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)3252 static Value *simplifyICmpWithBinOp(CmpPredicate Pred, Value *LHS, Value *RHS,
3253                                     const SimplifyQuery &Q,
3254                                     unsigned MaxRecurse) {
3255   BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
3256   BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
3257   if (MaxRecurse && (LBO || RBO)) {
3258     // Analyze the case when either LHS or RHS is an add instruction.
3259     Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
3260     // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
3261     bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
3262     if (LBO && LBO->getOpcode() == Instruction::Add) {
3263       A = LBO->getOperand(0);
3264       B = LBO->getOperand(1);
3265       NoLHSWrapProblem =
3266           ICmpInst::isEquality(Pred) ||
3267           (CmpInst::isUnsigned(Pred) &&
3268            Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO))) ||
3269           (CmpInst::isSigned(Pred) &&
3270            Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)));
3271     }
3272     if (RBO && RBO->getOpcode() == Instruction::Add) {
3273       C = RBO->getOperand(0);
3274       D = RBO->getOperand(1);
3275       NoRHSWrapProblem =
3276           ICmpInst::isEquality(Pred) ||
3277           (CmpInst::isUnsigned(Pred) &&
3278            Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(RBO))) ||
3279           (CmpInst::isSigned(Pred) &&
3280            Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RBO)));
3281     }
3282 
3283     // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
3284     if ((A == RHS || B == RHS) && NoLHSWrapProblem)
3285       if (Value *V = simplifyICmpInst(Pred, A == RHS ? B : A,
3286                                       Constant::getNullValue(RHS->getType()), Q,
3287                                       MaxRecurse - 1))
3288         return V;
3289 
3290     // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
3291     if ((C == LHS || D == LHS) && NoRHSWrapProblem)
3292       if (Value *V =
3293               simplifyICmpInst(Pred, Constant::getNullValue(LHS->getType()),
3294                                C == LHS ? D : C, Q, MaxRecurse - 1))
3295         return V;
3296 
3297     // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
3298     bool CanSimplify = (NoLHSWrapProblem && NoRHSWrapProblem) ||
3299                        trySimplifyICmpWithAdds(Pred, LHS, RHS, Q.IIQ);
3300     if (A && C && (A == C || A == D || B == C || B == D) && CanSimplify) {
3301       // Determine Y and Z in the form icmp (X+Y), (X+Z).
3302       Value *Y, *Z;
3303       if (A == C) {
3304         // C + B == C + D  ->  B == D
3305         Y = B;
3306         Z = D;
3307       } else if (A == D) {
3308         // D + B == C + D  ->  B == C
3309         Y = B;
3310         Z = C;
3311       } else if (B == C) {
3312         // A + C == C + D  ->  A == D
3313         Y = A;
3314         Z = D;
3315       } else {
3316         assert(B == D);
3317         // A + D == C + D  ->  A == C
3318         Y = A;
3319         Z = C;
3320       }
3321       if (Value *V = simplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1))
3322         return V;
3323     }
3324   }
3325 
3326   if (LBO)
3327     if (Value *V = simplifyICmpWithBinOpOnLHS(Pred, LBO, RHS, Q, MaxRecurse))
3328       return V;
3329 
3330   if (RBO)
3331     if (Value *V = simplifyICmpWithBinOpOnLHS(
3332             ICmpInst::getSwappedPredicate(Pred), RBO, LHS, Q, MaxRecurse))
3333       return V;
3334 
3335   // 0 - (zext X) pred C
3336   if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
3337     const APInt *C;
3338     if (match(RHS, m_APInt(C))) {
3339       if (C->isStrictlyPositive()) {
3340         if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_NE)
3341           return ConstantInt::getTrue(getCompareTy(RHS));
3342         if (Pred == ICmpInst::ICMP_SGE || Pred == ICmpInst::ICMP_EQ)
3343           return ConstantInt::getFalse(getCompareTy(RHS));
3344       }
3345       if (C->isNonNegative()) {
3346         if (Pred == ICmpInst::ICMP_SLE)
3347           return ConstantInt::getTrue(getCompareTy(RHS));
3348         if (Pred == ICmpInst::ICMP_SGT)
3349           return ConstantInt::getFalse(getCompareTy(RHS));
3350       }
3351     }
3352   }
3353 
3354   //   If C2 is a power-of-2 and C is not:
3355   //   (C2 << X) == C --> false
3356   //   (C2 << X) != C --> true
3357   const APInt *C;
3358   if (match(LHS, m_Shl(m_Power2(), m_Value())) &&
3359       match(RHS, m_APIntAllowPoison(C)) && !C->isPowerOf2()) {
3360     // C2 << X can equal zero in some circumstances.
3361     // This simplification might be unsafe if C is zero.
3362     //
3363     // We know it is safe if:
3364     // - The shift is nsw. We can't shift out the one bit.
3365     // - The shift is nuw. We can't shift out the one bit.
3366     // - C2 is one.
3367     // - C isn't zero.
3368     if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) ||
3369         Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) ||
3370         match(LHS, m_Shl(m_One(), m_Value())) || !C->isZero()) {
3371       if (Pred == ICmpInst::ICMP_EQ)
3372         return ConstantInt::getFalse(getCompareTy(RHS));
3373       if (Pred == ICmpInst::ICMP_NE)
3374         return ConstantInt::getTrue(getCompareTy(RHS));
3375     }
3376   }
3377 
3378   // If C is a power-of-2:
3379   // (C << X)  >u 0x8000 --> false
3380   // (C << X) <=u 0x8000 --> true
3381   if (match(LHS, m_Shl(m_Power2(), m_Value())) && match(RHS, m_SignMask())) {
3382     if (Pred == ICmpInst::ICMP_UGT)
3383       return ConstantInt::getFalse(getCompareTy(RHS));
3384     if (Pred == ICmpInst::ICMP_ULE)
3385       return ConstantInt::getTrue(getCompareTy(RHS));
3386   }
3387 
3388   if (!MaxRecurse || !LBO || !RBO || LBO->getOpcode() != RBO->getOpcode())
3389     return nullptr;
3390 
3391   if (LBO->getOperand(0) == RBO->getOperand(0)) {
3392     switch (LBO->getOpcode()) {
3393     default:
3394       break;
3395     case Instruction::Shl: {
3396       bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO);
3397       bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO);
3398       if (!NUW || (ICmpInst::isSigned(Pred) && !NSW) ||
3399           !isKnownNonZero(LBO->getOperand(0), Q))
3400         break;
3401       if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(1),
3402                                       RBO->getOperand(1), Q, MaxRecurse - 1))
3403         return V;
3404       break;
3405     }
3406     // If C1 & C2 == C1, A = X and/or C1, B = X and/or C2:
3407     // icmp ule A, B -> true
3408     // icmp ugt A, B -> false
3409     // icmp sle A, B -> true (C1 and C2 are the same sign)
3410     // icmp sgt A, B -> false (C1 and C2 are the same sign)
3411     case Instruction::And:
3412     case Instruction::Or: {
3413       const APInt *C1, *C2;
3414       if (ICmpInst::isRelational(Pred) &&
3415           match(LBO->getOperand(1), m_APInt(C1)) &&
3416           match(RBO->getOperand(1), m_APInt(C2))) {
3417         if (!C1->isSubsetOf(*C2)) {
3418           std::swap(C1, C2);
3419           Pred = ICmpInst::getSwappedPredicate(Pred);
3420         }
3421         if (C1->isSubsetOf(*C2)) {
3422           if (Pred == ICmpInst::ICMP_ULE)
3423             return ConstantInt::getTrue(getCompareTy(LHS));
3424           if (Pred == ICmpInst::ICMP_UGT)
3425             return ConstantInt::getFalse(getCompareTy(LHS));
3426           if (C1->isNonNegative() == C2->isNonNegative()) {
3427             if (Pred == ICmpInst::ICMP_SLE)
3428               return ConstantInt::getTrue(getCompareTy(LHS));
3429             if (Pred == ICmpInst::ICMP_SGT)
3430               return ConstantInt::getFalse(getCompareTy(LHS));
3431           }
3432         }
3433       }
3434       break;
3435     }
3436     }
3437   }
3438 
3439   if (LBO->getOperand(1) == RBO->getOperand(1)) {
3440     switch (LBO->getOpcode()) {
3441     default:
3442       break;
3443     case Instruction::UDiv:
3444     case Instruction::LShr:
3445       if (ICmpInst::isSigned(Pred) || !Q.IIQ.isExact(LBO) ||
3446           !Q.IIQ.isExact(RBO))
3447         break;
3448       if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0),
3449                                       RBO->getOperand(0), Q, MaxRecurse - 1))
3450         return V;
3451       break;
3452     case Instruction::SDiv:
3453       if (!ICmpInst::isEquality(Pred) || !Q.IIQ.isExact(LBO) ||
3454           !Q.IIQ.isExact(RBO))
3455         break;
3456       if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0),
3457                                       RBO->getOperand(0), Q, MaxRecurse - 1))
3458         return V;
3459       break;
3460     case Instruction::AShr:
3461       if (!Q.IIQ.isExact(LBO) || !Q.IIQ.isExact(RBO))
3462         break;
3463       if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0),
3464                                       RBO->getOperand(0), Q, MaxRecurse - 1))
3465         return V;
3466       break;
3467     case Instruction::Shl: {
3468       bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO);
3469       bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO);
3470       if (!NUW && !NSW)
3471         break;
3472       if (!NSW && ICmpInst::isSigned(Pred))
3473         break;
3474       if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0),
3475                                       RBO->getOperand(0), Q, MaxRecurse - 1))
3476         return V;
3477       break;
3478     }
3479     }
3480   }
3481   return nullptr;
3482 }
3483 
3484 /// simplify integer comparisons where at least one operand of the compare
3485 /// matches an integer min/max idiom.
simplifyICmpWithMinMax(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)3486 static Value *simplifyICmpWithMinMax(CmpPredicate Pred, Value *LHS, Value *RHS,
3487                                      const SimplifyQuery &Q,
3488                                      unsigned MaxRecurse) {
3489   Type *ITy = getCompareTy(LHS); // The return type.
3490   Value *A, *B;
3491   CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
3492   CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
3493 
3494   // Signed variants on "max(a,b)>=a -> true".
3495   if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
3496     if (A != RHS)
3497       std::swap(A, B);       // smax(A, B) pred A.
3498     EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
3499     // We analyze this as smax(A, B) pred A.
3500     P = Pred;
3501   } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
3502              (A == LHS || B == LHS)) {
3503     if (A != LHS)
3504       std::swap(A, B);       // A pred smax(A, B).
3505     EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
3506     // We analyze this as smax(A, B) swapped-pred A.
3507     P = CmpInst::getSwappedPredicate(Pred);
3508   } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
3509              (A == RHS || B == RHS)) {
3510     if (A != RHS)
3511       std::swap(A, B);       // smin(A, B) pred A.
3512     EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
3513     // We analyze this as smax(-A, -B) swapped-pred -A.
3514     // Note that we do not need to actually form -A or -B thanks to EqP.
3515     P = CmpInst::getSwappedPredicate(Pred);
3516   } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
3517              (A == LHS || B == LHS)) {
3518     if (A != LHS)
3519       std::swap(A, B);       // A pred smin(A, B).
3520     EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
3521     // We analyze this as smax(-A, -B) pred -A.
3522     // Note that we do not need to actually form -A or -B thanks to EqP.
3523     P = Pred;
3524   }
3525   if (P != CmpInst::BAD_ICMP_PREDICATE) {
3526     // Cases correspond to "max(A, B) p A".
3527     switch (P) {
3528     default:
3529       break;
3530     case CmpInst::ICMP_EQ:
3531     case CmpInst::ICMP_SLE:
3532       // Equivalent to "A EqP B".  This may be the same as the condition tested
3533       // in the max/min; if so, we can just return that.
3534       if (Value *V = extractEquivalentCondition(LHS, EqP, A, B))
3535         return V;
3536       if (Value *V = extractEquivalentCondition(RHS, EqP, A, B))
3537         return V;
3538       // Otherwise, see if "A EqP B" simplifies.
3539       if (MaxRecurse)
3540         if (Value *V = simplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
3541           return V;
3542       break;
3543     case CmpInst::ICMP_NE:
3544     case CmpInst::ICMP_SGT: {
3545       CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
3546       // Equivalent to "A InvEqP B".  This may be the same as the condition
3547       // tested in the max/min; if so, we can just return that.
3548       if (Value *V = extractEquivalentCondition(LHS, InvEqP, A, B))
3549         return V;
3550       if (Value *V = extractEquivalentCondition(RHS, InvEqP, A, B))
3551         return V;
3552       // Otherwise, see if "A InvEqP B" simplifies.
3553       if (MaxRecurse)
3554         if (Value *V = simplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
3555           return V;
3556       break;
3557     }
3558     case CmpInst::ICMP_SGE:
3559       // Always true.
3560       return getTrue(ITy);
3561     case CmpInst::ICMP_SLT:
3562       // Always false.
3563       return getFalse(ITy);
3564     }
3565   }
3566 
3567   // Unsigned variants on "max(a,b)>=a -> true".
3568   P = CmpInst::BAD_ICMP_PREDICATE;
3569   if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
3570     if (A != RHS)
3571       std::swap(A, B);       // umax(A, B) pred A.
3572     EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
3573     // We analyze this as umax(A, B) pred A.
3574     P = Pred;
3575   } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
3576              (A == LHS || B == LHS)) {
3577     if (A != LHS)
3578       std::swap(A, B);       // A pred umax(A, B).
3579     EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
3580     // We analyze this as umax(A, B) swapped-pred A.
3581     P = CmpInst::getSwappedPredicate(Pred);
3582   } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
3583              (A == RHS || B == RHS)) {
3584     if (A != RHS)
3585       std::swap(A, B);       // umin(A, B) pred A.
3586     EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
3587     // We analyze this as umax(-A, -B) swapped-pred -A.
3588     // Note that we do not need to actually form -A or -B thanks to EqP.
3589     P = CmpInst::getSwappedPredicate(Pred);
3590   } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
3591              (A == LHS || B == LHS)) {
3592     if (A != LHS)
3593       std::swap(A, B);       // A pred umin(A, B).
3594     EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
3595     // We analyze this as umax(-A, -B) pred -A.
3596     // Note that we do not need to actually form -A or -B thanks to EqP.
3597     P = Pred;
3598   }
3599   if (P != CmpInst::BAD_ICMP_PREDICATE) {
3600     // Cases correspond to "max(A, B) p A".
3601     switch (P) {
3602     default:
3603       break;
3604     case CmpInst::ICMP_EQ:
3605     case CmpInst::ICMP_ULE:
3606       // Equivalent to "A EqP B".  This may be the same as the condition tested
3607       // in the max/min; if so, we can just return that.
3608       if (Value *V = extractEquivalentCondition(LHS, EqP, A, B))
3609         return V;
3610       if (Value *V = extractEquivalentCondition(RHS, EqP, A, B))
3611         return V;
3612       // Otherwise, see if "A EqP B" simplifies.
3613       if (MaxRecurse)
3614         if (Value *V = simplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1))
3615           return V;
3616       break;
3617     case CmpInst::ICMP_NE:
3618     case CmpInst::ICMP_UGT: {
3619       CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
3620       // Equivalent to "A InvEqP B".  This may be the same as the condition
3621       // tested in the max/min; if so, we can just return that.
3622       if (Value *V = extractEquivalentCondition(LHS, InvEqP, A, B))
3623         return V;
3624       if (Value *V = extractEquivalentCondition(RHS, InvEqP, A, B))
3625         return V;
3626       // Otherwise, see if "A InvEqP B" simplifies.
3627       if (MaxRecurse)
3628         if (Value *V = simplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1))
3629           return V;
3630       break;
3631     }
3632     case CmpInst::ICMP_UGE:
3633       return getTrue(ITy);
3634     case CmpInst::ICMP_ULT:
3635       return getFalse(ITy);
3636     }
3637   }
3638 
3639   // Comparing 1 each of min/max with a common operand?
3640   // Canonicalize min operand to RHS.
3641   if (match(LHS, m_UMin(m_Value(), m_Value())) ||
3642       match(LHS, m_SMin(m_Value(), m_Value()))) {
3643     std::swap(LHS, RHS);
3644     Pred = ICmpInst::getSwappedPredicate(Pred);
3645   }
3646 
3647   Value *C, *D;
3648   if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
3649       match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
3650       (A == C || A == D || B == C || B == D)) {
3651     // smax(A, B) >=s smin(A, D) --> true
3652     if (Pred == CmpInst::ICMP_SGE)
3653       return getTrue(ITy);
3654     // smax(A, B) <s smin(A, D) --> false
3655     if (Pred == CmpInst::ICMP_SLT)
3656       return getFalse(ITy);
3657   } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
3658              match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
3659              (A == C || A == D || B == C || B == D)) {
3660     // umax(A, B) >=u umin(A, D) --> true
3661     if (Pred == CmpInst::ICMP_UGE)
3662       return getTrue(ITy);
3663     // umax(A, B) <u umin(A, D) --> false
3664     if (Pred == CmpInst::ICMP_ULT)
3665       return getFalse(ITy);
3666   }
3667 
3668   return nullptr;
3669 }
3670 
simplifyICmpWithDominatingAssume(CmpPredicate Predicate,Value * LHS,Value * RHS,const SimplifyQuery & Q)3671 static Value *simplifyICmpWithDominatingAssume(CmpPredicate Predicate,
3672                                                Value *LHS, Value *RHS,
3673                                                const SimplifyQuery &Q) {
3674   // Gracefully handle instructions that have not been inserted yet.
3675   if (!Q.AC || !Q.CxtI)
3676     return nullptr;
3677 
3678   for (Value *AssumeBaseOp : {LHS, RHS}) {
3679     for (auto &AssumeVH : Q.AC->assumptionsFor(AssumeBaseOp)) {
3680       if (!AssumeVH)
3681         continue;
3682 
3683       CallInst *Assume = cast<CallInst>(AssumeVH);
3684       if (std::optional<bool> Imp = isImpliedCondition(
3685               Assume->getArgOperand(0), Predicate, LHS, RHS, Q.DL))
3686         if (isValidAssumeForContext(Assume, Q.CxtI, Q.DT))
3687           return ConstantInt::get(getCompareTy(LHS), *Imp);
3688     }
3689   }
3690 
3691   return nullptr;
3692 }
3693 
simplifyICmpWithIntrinsicOnLHS(CmpPredicate Pred,Value * LHS,Value * RHS)3694 static Value *simplifyICmpWithIntrinsicOnLHS(CmpPredicate Pred, Value *LHS,
3695                                              Value *RHS) {
3696   auto *II = dyn_cast<IntrinsicInst>(LHS);
3697   if (!II)
3698     return nullptr;
3699 
3700   switch (II->getIntrinsicID()) {
3701   case Intrinsic::uadd_sat:
3702     // uadd.sat(X, Y) uge X + Y
3703     if (match(RHS, m_c_Add(m_Specific(II->getArgOperand(0)),
3704                            m_Specific(II->getArgOperand(1))))) {
3705       if (Pred == ICmpInst::ICMP_UGE)
3706         return ConstantInt::getTrue(getCompareTy(II));
3707       if (Pred == ICmpInst::ICMP_ULT)
3708         return ConstantInt::getFalse(getCompareTy(II));
3709     }
3710     return nullptr;
3711   case Intrinsic::usub_sat:
3712     // usub.sat(X, Y) ule X - Y
3713     if (match(RHS, m_Sub(m_Specific(II->getArgOperand(0)),
3714                          m_Specific(II->getArgOperand(1))))) {
3715       if (Pred == ICmpInst::ICMP_ULE)
3716         return ConstantInt::getTrue(getCompareTy(II));
3717       if (Pred == ICmpInst::ICMP_UGT)
3718         return ConstantInt::getFalse(getCompareTy(II));
3719     }
3720     return nullptr;
3721   default:
3722     return nullptr;
3723   }
3724 }
3725 
3726 /// Helper method to get range from metadata or attribute.
getRange(Value * V,const InstrInfoQuery & IIQ)3727 static std::optional<ConstantRange> getRange(Value *V,
3728                                              const InstrInfoQuery &IIQ) {
3729   if (Instruction *I = dyn_cast<Instruction>(V))
3730     if (MDNode *MD = IIQ.getMetadata(I, LLVMContext::MD_range))
3731       return getConstantRangeFromMetadata(*MD);
3732 
3733   if (const Argument *A = dyn_cast<Argument>(V))
3734     return A->getRange();
3735   else if (const CallBase *CB = dyn_cast<CallBase>(V))
3736     return CB->getRange();
3737 
3738   return std::nullopt;
3739 }
3740 
3741 /// Given operands for an ICmpInst, see if we can fold the result.
3742 /// If not, this returns null.
simplifyICmpInst(CmpPredicate Pred,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)3743 static Value *simplifyICmpInst(CmpPredicate Pred, Value *LHS, Value *RHS,
3744                                const SimplifyQuery &Q, unsigned MaxRecurse) {
3745   assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
3746 
3747   if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
3748     if (Constant *CRHS = dyn_cast<Constant>(RHS))
3749       return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
3750 
3751     // If we have a constant, make sure it is on the RHS.
3752     std::swap(LHS, RHS);
3753     Pred = CmpInst::getSwappedPredicate(Pred);
3754   }
3755   assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X");
3756 
3757   Type *ITy = getCompareTy(LHS); // The return type.
3758 
3759   // icmp poison, X -> poison
3760   if (isa<PoisonValue>(RHS))
3761     return PoisonValue::get(ITy);
3762 
3763   // For EQ and NE, we can always pick a value for the undef to make the
3764   // predicate pass or fail, so we can return undef.
3765   // Matches behavior in llvm::ConstantFoldCompareInstruction.
3766   if (Q.isUndefValue(RHS) && ICmpInst::isEquality(Pred))
3767     return UndefValue::get(ITy);
3768 
3769   // icmp X, X -> true/false
3770   // icmp X, undef -> true/false because undef could be X.
3771   if (LHS == RHS || Q.isUndefValue(RHS))
3772     return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
3773 
3774   if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
3775     return V;
3776 
3777   // TODO: Sink/common this with other potentially expensive calls that use
3778   //       ValueTracking? See comment below for isKnownNonEqual().
3779   if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
3780     return V;
3781 
3782   if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q))
3783     return V;
3784 
3785   // If both operands have range metadata, use the metadata
3786   // to simplify the comparison.
3787   if (std::optional<ConstantRange> RhsCr = getRange(RHS, Q.IIQ))
3788     if (std::optional<ConstantRange> LhsCr = getRange(LHS, Q.IIQ)) {
3789       if (LhsCr->icmp(Pred, *RhsCr))
3790         return ConstantInt::getTrue(ITy);
3791 
3792       if (LhsCr->icmp(CmpInst::getInversePredicate(Pred), *RhsCr))
3793         return ConstantInt::getFalse(ITy);
3794     }
3795 
3796   // Compare of cast, for example (zext X) != 0 -> X != 0
3797   if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
3798     Instruction *LI = cast<CastInst>(LHS);
3799     Value *SrcOp = LI->getOperand(0);
3800     Type *SrcTy = SrcOp->getType();
3801     Type *DstTy = LI->getType();
3802 
3803     // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
3804     // if the integer type is the same size as the pointer type.
3805     if (MaxRecurse && isa<PtrToIntInst>(LI) &&
3806         Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
3807       if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
3808         // Transfer the cast to the constant.
3809         if (Value *V = simplifyICmpInst(Pred, SrcOp,
3810                                         ConstantExpr::getIntToPtr(RHSC, SrcTy),
3811                                         Q, MaxRecurse - 1))
3812           return V;
3813       } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
3814         if (RI->getOperand(0)->getType() == SrcTy)
3815           // Compare without the cast.
3816           if (Value *V = simplifyICmpInst(Pred, SrcOp, RI->getOperand(0), Q,
3817                                           MaxRecurse - 1))
3818             return V;
3819       }
3820     }
3821 
3822     if (isa<ZExtInst>(LHS)) {
3823       // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
3824       // same type.
3825       if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
3826         if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3827           // Compare X and Y.  Note that signed predicates become unsigned.
3828           if (Value *V =
3829                   simplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), SrcOp,
3830                                    RI->getOperand(0), Q, MaxRecurse - 1))
3831             return V;
3832       }
3833       // Fold (zext X) ule (sext X), (zext X) sge (sext X) to true.
3834       else if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
3835         if (SrcOp == RI->getOperand(0)) {
3836           if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_SGE)
3837             return ConstantInt::getTrue(ITy);
3838           if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SLT)
3839             return ConstantInt::getFalse(ITy);
3840         }
3841       }
3842       // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
3843       // too.  If not, then try to deduce the result of the comparison.
3844       else if (match(RHS, m_ImmConstant())) {
3845         Constant *C = dyn_cast<Constant>(RHS);
3846         assert(C != nullptr);
3847 
3848         // Compute the constant that would happen if we truncated to SrcTy then
3849         // reextended to DstTy.
3850         Constant *Trunc =
3851             ConstantFoldCastOperand(Instruction::Trunc, C, SrcTy, Q.DL);
3852         assert(Trunc && "Constant-fold of ImmConstant should not fail");
3853         Constant *RExt =
3854             ConstantFoldCastOperand(CastInst::ZExt, Trunc, DstTy, Q.DL);
3855         assert(RExt && "Constant-fold of ImmConstant should not fail");
3856         Constant *AnyEq =
3857             ConstantFoldCompareInstOperands(ICmpInst::ICMP_EQ, RExt, C, Q.DL);
3858         assert(AnyEq && "Constant-fold of ImmConstant should not fail");
3859 
3860         // If the re-extended constant didn't change any of the elements then
3861         // this is effectively also a case of comparing two zero-extended
3862         // values.
3863         if (AnyEq->isAllOnesValue() && MaxRecurse)
3864           if (Value *V = simplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
3865                                           SrcOp, Trunc, Q, MaxRecurse - 1))
3866             return V;
3867 
3868         // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
3869         // there.  Use this to work out the result of the comparison.
3870         if (AnyEq->isNullValue()) {
3871           switch (Pred) {
3872           default:
3873             llvm_unreachable("Unknown ICmp predicate!");
3874           // LHS <u RHS.
3875           case ICmpInst::ICMP_EQ:
3876           case ICmpInst::ICMP_UGT:
3877           case ICmpInst::ICMP_UGE:
3878             return Constant::getNullValue(ITy);
3879 
3880           case ICmpInst::ICMP_NE:
3881           case ICmpInst::ICMP_ULT:
3882           case ICmpInst::ICMP_ULE:
3883             return Constant::getAllOnesValue(ITy);
3884 
3885           // LHS is non-negative.  If RHS is negative then LHS >s LHS.  If RHS
3886           // is non-negative then LHS <s RHS.
3887           case ICmpInst::ICMP_SGT:
3888           case ICmpInst::ICMP_SGE:
3889             return ConstantFoldCompareInstOperands(
3890                 ICmpInst::ICMP_SLT, C, Constant::getNullValue(C->getType()),
3891                 Q.DL);
3892           case ICmpInst::ICMP_SLT:
3893           case ICmpInst::ICMP_SLE:
3894             return ConstantFoldCompareInstOperands(
3895                 ICmpInst::ICMP_SGE, C, Constant::getNullValue(C->getType()),
3896                 Q.DL);
3897           }
3898         }
3899       }
3900     }
3901 
3902     if (isa<SExtInst>(LHS)) {
3903       // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
3904       // same type.
3905       if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
3906         if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
3907           // Compare X and Y.  Note that the predicate does not change.
3908           if (Value *V = simplifyICmpInst(Pred, SrcOp, RI->getOperand(0), Q,
3909                                           MaxRecurse - 1))
3910             return V;
3911       }
3912       // Fold (sext X) uge (zext X), (sext X) sle (zext X) to true.
3913       else if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
3914         if (SrcOp == RI->getOperand(0)) {
3915           if (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_SLE)
3916             return ConstantInt::getTrue(ITy);
3917           if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SGT)
3918             return ConstantInt::getFalse(ITy);
3919         }
3920       }
3921       // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
3922       // too.  If not, then try to deduce the result of the comparison.
3923       else if (match(RHS, m_ImmConstant())) {
3924         Constant *C = cast<Constant>(RHS);
3925 
3926         // Compute the constant that would happen if we truncated to SrcTy then
3927         // reextended to DstTy.
3928         Constant *Trunc =
3929             ConstantFoldCastOperand(Instruction::Trunc, C, SrcTy, Q.DL);
3930         assert(Trunc && "Constant-fold of ImmConstant should not fail");
3931         Constant *RExt =
3932             ConstantFoldCastOperand(CastInst::SExt, Trunc, DstTy, Q.DL);
3933         assert(RExt && "Constant-fold of ImmConstant should not fail");
3934         Constant *AnyEq =
3935             ConstantFoldCompareInstOperands(ICmpInst::ICMP_EQ, RExt, C, Q.DL);
3936         assert(AnyEq && "Constant-fold of ImmConstant should not fail");
3937 
3938         // If the re-extended constant didn't change then this is effectively
3939         // also a case of comparing two sign-extended values.
3940         if (AnyEq->isAllOnesValue() && MaxRecurse)
3941           if (Value *V =
3942                   simplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse - 1))
3943             return V;
3944 
3945         // Otherwise the upper bits of LHS are all equal, while RHS has varying
3946         // bits there.  Use this to work out the result of the comparison.
3947         if (AnyEq->isNullValue()) {
3948           switch (Pred) {
3949           default:
3950             llvm_unreachable("Unknown ICmp predicate!");
3951           case ICmpInst::ICMP_EQ:
3952             return Constant::getNullValue(ITy);
3953           case ICmpInst::ICMP_NE:
3954             return Constant::getAllOnesValue(ITy);
3955 
3956           // If RHS is non-negative then LHS <s RHS.  If RHS is negative then
3957           // LHS >s RHS.
3958           case ICmpInst::ICMP_SGT:
3959           case ICmpInst::ICMP_SGE:
3960             return ConstantFoldCompareInstOperands(
3961                 ICmpInst::ICMP_SLT, C, Constant::getNullValue(C->getType()),
3962                 Q.DL);
3963           case ICmpInst::ICMP_SLT:
3964           case ICmpInst::ICMP_SLE:
3965             return ConstantFoldCompareInstOperands(
3966                 ICmpInst::ICMP_SGE, C, Constant::getNullValue(C->getType()),
3967                 Q.DL);
3968 
3969           // If LHS is non-negative then LHS <u RHS.  If LHS is negative then
3970           // LHS >u RHS.
3971           case ICmpInst::ICMP_UGT:
3972           case ICmpInst::ICMP_UGE:
3973             // Comparison is true iff the LHS <s 0.
3974             if (MaxRecurse)
3975               if (Value *V = simplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
3976                                               Constant::getNullValue(SrcTy), Q,
3977                                               MaxRecurse - 1))
3978                 return V;
3979             break;
3980           case ICmpInst::ICMP_ULT:
3981           case ICmpInst::ICMP_ULE:
3982             // Comparison is true iff the LHS >=s 0.
3983             if (MaxRecurse)
3984               if (Value *V = simplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
3985                                               Constant::getNullValue(SrcTy), Q,
3986                                               MaxRecurse - 1))
3987                 return V;
3988             break;
3989           }
3990         }
3991       }
3992     }
3993   }
3994 
3995   // icmp eq|ne X, Y -> false|true if X != Y
3996   // This is potentially expensive, and we have already computedKnownBits for
3997   // compares with 0 above here, so only try this for a non-zero compare.
3998   if (ICmpInst::isEquality(Pred) && !match(RHS, m_Zero()) &&
3999       isKnownNonEqual(LHS, RHS, Q)) {
4000     return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy);
4001   }
4002 
4003   if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse))
4004     return V;
4005 
4006   if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse))
4007     return V;
4008 
4009   if (Value *V = simplifyICmpWithIntrinsicOnLHS(Pred, LHS, RHS))
4010     return V;
4011   if (Value *V = simplifyICmpWithIntrinsicOnLHS(
4012           ICmpInst::getSwappedPredicate(Pred), RHS, LHS))
4013     return V;
4014 
4015   if (Value *V = simplifyICmpUsingMonotonicValues(Pred, LHS, RHS, Q))
4016     return V;
4017   if (Value *V = simplifyICmpUsingMonotonicValues(
4018           ICmpInst::getSwappedPredicate(Pred), RHS, LHS, Q))
4019     return V;
4020 
4021   if (Value *V = simplifyICmpWithDominatingAssume(Pred, LHS, RHS, Q))
4022     return V;
4023 
4024   if (std::optional<bool> Res =
4025           isImpliedByDomCondition(Pred, LHS, RHS, Q.CxtI, Q.DL))
4026     return ConstantInt::getBool(ITy, *Res);
4027 
4028   // Simplify comparisons of related pointers using a powerful, recursive
4029   // GEP-walk when we have target data available..
4030   if (LHS->getType()->isPointerTy())
4031     if (auto *C = computePointerICmp(Pred, LHS, RHS, Q))
4032       return C;
4033   if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS))
4034     if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS))
4035       if (CLHS->getPointerOperandType() == CRHS->getPointerOperandType() &&
4036           Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) ==
4037               Q.DL.getTypeSizeInBits(CLHS->getType()))
4038         if (auto *C = computePointerICmp(Pred, CLHS->getPointerOperand(),
4039                                          CRHS->getPointerOperand(), Q))
4040           return C;
4041 
4042   // If the comparison is with the result of a select instruction, check whether
4043   // comparing with either branch of the select always yields the same value.
4044   if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
4045     if (Value *V = threadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
4046       return V;
4047 
4048   // If the comparison is with the result of a phi instruction, check whether
4049   // doing the compare with each incoming phi value yields a common result.
4050   if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
4051     if (Value *V = threadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
4052       return V;
4053 
4054   return nullptr;
4055 }
4056 
simplifyICmpInst(CmpPredicate Predicate,Value * LHS,Value * RHS,const SimplifyQuery & Q)4057 Value *llvm::simplifyICmpInst(CmpPredicate Predicate, Value *LHS, Value *RHS,
4058                               const SimplifyQuery &Q) {
4059   return ::simplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
4060 }
4061 
4062 /// Given operands for an FCmpInst, see if we can fold the result.
4063 /// If not, this returns null.
simplifyFCmpInst(CmpPredicate Pred,Value * LHS,Value * RHS,FastMathFlags FMF,const SimplifyQuery & Q,unsigned MaxRecurse)4064 static Value *simplifyFCmpInst(CmpPredicate Pred, Value *LHS, Value *RHS,
4065                                FastMathFlags FMF, const SimplifyQuery &Q,
4066                                unsigned MaxRecurse) {
4067   assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
4068 
4069   if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
4070     if (Constant *CRHS = dyn_cast<Constant>(RHS))
4071       return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI,
4072                                              Q.CxtI);
4073 
4074     // If we have a constant, make sure it is on the RHS.
4075     std::swap(LHS, RHS);
4076     Pred = CmpInst::getSwappedPredicate(Pred);
4077   }
4078 
4079   // Fold trivial predicates.
4080   Type *RetTy = getCompareTy(LHS);
4081   if (Pred == FCmpInst::FCMP_FALSE)
4082     return getFalse(RetTy);
4083   if (Pred == FCmpInst::FCMP_TRUE)
4084     return getTrue(RetTy);
4085 
4086   // fcmp pred x, poison and  fcmp pred poison, x
4087   // fold to poison
4088   if (isa<PoisonValue>(LHS) || isa<PoisonValue>(RHS))
4089     return PoisonValue::get(RetTy);
4090 
4091   // fcmp pred x, undef  and  fcmp pred undef, x
4092   // fold to true if unordered, false if ordered
4093   if (Q.isUndefValue(LHS) || Q.isUndefValue(RHS)) {
4094     // Choosing NaN for the undef will always make unordered comparison succeed
4095     // and ordered comparison fail.
4096     return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
4097   }
4098 
4099   // fcmp x,x -> true/false.  Not all compares are foldable.
4100   if (LHS == RHS) {
4101     if (CmpInst::isTrueWhenEqual(Pred))
4102       return getTrue(RetTy);
4103     if (CmpInst::isFalseWhenEqual(Pred))
4104       return getFalse(RetTy);
4105   }
4106 
4107   // Fold (un)ordered comparison if we can determine there are no NaNs.
4108   //
4109   // This catches the 2 variable input case, constants are handled below as a
4110   // class-like compare.
4111   if (Pred == FCmpInst::FCMP_ORD || Pred == FCmpInst::FCMP_UNO) {
4112     KnownFPClass RHSClass = computeKnownFPClass(RHS, fcAllFlags, Q);
4113     KnownFPClass LHSClass = computeKnownFPClass(LHS, fcAllFlags, Q);
4114 
4115     if (FMF.noNaNs() ||
4116         (RHSClass.isKnownNeverNaN() && LHSClass.isKnownNeverNaN()))
4117       return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD);
4118 
4119     if (RHSClass.isKnownAlwaysNaN() || LHSClass.isKnownAlwaysNaN())
4120       return ConstantInt::get(RetTy, Pred == CmpInst::FCMP_UNO);
4121   }
4122 
4123   const APFloat *C = nullptr;
4124   match(RHS, m_APFloatAllowPoison(C));
4125   std::optional<KnownFPClass> FullKnownClassLHS;
4126 
4127   // Lazily compute the possible classes for LHS. Avoid computing it twice if
4128   // RHS is a 0.
4129   auto computeLHSClass = [=, &FullKnownClassLHS](FPClassTest InterestedFlags =
4130                                                      fcAllFlags) {
4131     if (FullKnownClassLHS)
4132       return *FullKnownClassLHS;
4133     return computeKnownFPClass(LHS, FMF, InterestedFlags, Q);
4134   };
4135 
4136   if (C && Q.CxtI) {
4137     // Fold out compares that express a class test.
4138     //
4139     // FIXME: Should be able to perform folds without context
4140     // instruction. Always pass in the context function?
4141 
4142     const Function *ParentF = Q.CxtI->getFunction();
4143     auto [ClassVal, ClassTest] = fcmpToClassTest(Pred, *ParentF, LHS, C);
4144     if (ClassVal) {
4145       FullKnownClassLHS = computeLHSClass();
4146       if ((FullKnownClassLHS->KnownFPClasses & ClassTest) == fcNone)
4147         return getFalse(RetTy);
4148       if ((FullKnownClassLHS->KnownFPClasses & ~ClassTest) == fcNone)
4149         return getTrue(RetTy);
4150     }
4151   }
4152 
4153   // Handle fcmp with constant RHS.
4154   if (C) {
4155     // TODO: If we always required a context function, we wouldn't need to
4156     // special case nans.
4157     if (C->isNaN())
4158       return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
4159 
4160     // TODO: Need version fcmpToClassTest which returns implied class when the
4161     // compare isn't a complete class test. e.g. > 1.0 implies fcPositive, but
4162     // isn't implementable as a class call.
4163     if (C->isNegative() && !C->isNegZero()) {
4164       FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask;
4165 
4166       // TODO: We can catch more cases by using a range check rather than
4167       //       relying on CannotBeOrderedLessThanZero.
4168       switch (Pred) {
4169       case FCmpInst::FCMP_UGE:
4170       case FCmpInst::FCMP_UGT:
4171       case FCmpInst::FCMP_UNE: {
4172         KnownFPClass KnownClass = computeLHSClass(Interested);
4173 
4174         // (X >= 0) implies (X > C) when (C < 0)
4175         if (KnownClass.cannotBeOrderedLessThanZero())
4176           return getTrue(RetTy);
4177         break;
4178       }
4179       case FCmpInst::FCMP_OEQ:
4180       case FCmpInst::FCMP_OLE:
4181       case FCmpInst::FCMP_OLT: {
4182         KnownFPClass KnownClass = computeLHSClass(Interested);
4183 
4184         // (X >= 0) implies !(X < C) when (C < 0)
4185         if (KnownClass.cannotBeOrderedLessThanZero())
4186           return getFalse(RetTy);
4187         break;
4188       }
4189       default:
4190         break;
4191       }
4192     }
4193     // Check comparison of [minnum/maxnum with constant] with other constant.
4194     const APFloat *C2;
4195     if ((match(LHS, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_APFloat(C2))) &&
4196          *C2 < *C) ||
4197         (match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) &&
4198          *C2 > *C)) {
4199       bool IsMaxNum =
4200           cast<IntrinsicInst>(LHS)->getIntrinsicID() == Intrinsic::maxnum;
4201       // The ordered relationship and minnum/maxnum guarantee that we do not
4202       // have NaN constants, so ordered/unordered preds are handled the same.
4203       switch (Pred) {
4204       case FCmpInst::FCMP_OEQ:
4205       case FCmpInst::FCMP_UEQ:
4206         // minnum(X, LesserC)  == C --> false
4207         // maxnum(X, GreaterC) == C --> false
4208         return getFalse(RetTy);
4209       case FCmpInst::FCMP_ONE:
4210       case FCmpInst::FCMP_UNE:
4211         // minnum(X, LesserC)  != C --> true
4212         // maxnum(X, GreaterC) != C --> true
4213         return getTrue(RetTy);
4214       case FCmpInst::FCMP_OGE:
4215       case FCmpInst::FCMP_UGE:
4216       case FCmpInst::FCMP_OGT:
4217       case FCmpInst::FCMP_UGT:
4218         // minnum(X, LesserC)  >= C --> false
4219         // minnum(X, LesserC)  >  C --> false
4220         // maxnum(X, GreaterC) >= C --> true
4221         // maxnum(X, GreaterC) >  C --> true
4222         return ConstantInt::get(RetTy, IsMaxNum);
4223       case FCmpInst::FCMP_OLE:
4224       case FCmpInst::FCMP_ULE:
4225       case FCmpInst::FCMP_OLT:
4226       case FCmpInst::FCMP_ULT:
4227         // minnum(X, LesserC)  <= C --> true
4228         // minnum(X, LesserC)  <  C --> true
4229         // maxnum(X, GreaterC) <= C --> false
4230         // maxnum(X, GreaterC) <  C --> false
4231         return ConstantInt::get(RetTy, !IsMaxNum);
4232       default:
4233         // TRUE/FALSE/ORD/UNO should be handled before this.
4234         llvm_unreachable("Unexpected fcmp predicate");
4235       }
4236     }
4237   }
4238 
4239   // TODO: Could fold this with above if there were a matcher which returned all
4240   // classes in a non-splat vector.
4241   if (match(RHS, m_AnyZeroFP())) {
4242     switch (Pred) {
4243     case FCmpInst::FCMP_OGE:
4244     case FCmpInst::FCMP_ULT: {
4245       FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask;
4246       if (!FMF.noNaNs())
4247         Interested |= fcNan;
4248 
4249       KnownFPClass Known = computeLHSClass(Interested);
4250 
4251       // Positive or zero X >= 0.0 --> true
4252       // Positive or zero X <  0.0 --> false
4253       if ((FMF.noNaNs() || Known.isKnownNeverNaN()) &&
4254           Known.cannotBeOrderedLessThanZero())
4255         return Pred == FCmpInst::FCMP_OGE ? getTrue(RetTy) : getFalse(RetTy);
4256       break;
4257     }
4258     case FCmpInst::FCMP_UGE:
4259     case FCmpInst::FCMP_OLT: {
4260       FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask;
4261       KnownFPClass Known = computeLHSClass(Interested);
4262 
4263       // Positive or zero or nan X >= 0.0 --> true
4264       // Positive or zero or nan X <  0.0 --> false
4265       if (Known.cannotBeOrderedLessThanZero())
4266         return Pred == FCmpInst::FCMP_UGE ? getTrue(RetTy) : getFalse(RetTy);
4267       break;
4268     }
4269     default:
4270       break;
4271     }
4272   }
4273 
4274   // If the comparison is with the result of a select instruction, check whether
4275   // comparing with either branch of the select always yields the same value.
4276   if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
4277     if (Value *V = threadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
4278       return V;
4279 
4280   // If the comparison is with the result of a phi instruction, check whether
4281   // doing the compare with each incoming phi value yields a common result.
4282   if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
4283     if (Value *V = threadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
4284       return V;
4285 
4286   return nullptr;
4287 }
4288 
simplifyFCmpInst(CmpPredicate Predicate,Value * LHS,Value * RHS,FastMathFlags FMF,const SimplifyQuery & Q)4289 Value *llvm::simplifyFCmpInst(CmpPredicate Predicate, Value *LHS, Value *RHS,
4290                               FastMathFlags FMF, const SimplifyQuery &Q) {
4291   return ::simplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit);
4292 }
4293 
simplifyWithOpsReplaced(Value * V,ArrayRef<std::pair<Value *,Value * >> Ops,const SimplifyQuery & Q,bool AllowRefinement,SmallVectorImpl<Instruction * > * DropFlags,unsigned MaxRecurse)4294 static Value *simplifyWithOpsReplaced(Value *V,
4295                                       ArrayRef<std::pair<Value *, Value *>> Ops,
4296                                       const SimplifyQuery &Q,
4297                                       bool AllowRefinement,
4298                                       SmallVectorImpl<Instruction *> *DropFlags,
4299                                       unsigned MaxRecurse) {
4300   assert((AllowRefinement || !Q.CanUseUndef) &&
4301          "If AllowRefinement=false then CanUseUndef=false");
4302   for (const auto &OpAndRepOp : Ops) {
4303     // We cannot replace a constant, and shouldn't even try.
4304     if (isa<Constant>(OpAndRepOp.first))
4305       return nullptr;
4306 
4307     // Trivial replacement.
4308     if (V == OpAndRepOp.first)
4309       return OpAndRepOp.second;
4310   }
4311 
4312   if (!MaxRecurse--)
4313     return nullptr;
4314 
4315   auto *I = dyn_cast<Instruction>(V);
4316   if (!I)
4317     return nullptr;
4318 
4319   // The arguments of a phi node might refer to a value from a previous
4320   // cycle iteration.
4321   if (isa<PHINode>(I))
4322     return nullptr;
4323 
4324   // Don't fold away llvm.is.constant checks based on assumptions.
4325   if (match(I, m_Intrinsic<Intrinsic::is_constant>()))
4326     return nullptr;
4327 
4328   // Don't simplify freeze.
4329   if (isa<FreezeInst>(I))
4330     return nullptr;
4331 
4332   for (const auto &OpAndRepOp : Ops) {
4333     // For vector types, the simplification must hold per-lane, so forbid
4334     // potentially cross-lane operations like shufflevector.
4335     if (OpAndRepOp.first->getType()->isVectorTy() &&
4336         !isNotCrossLaneOperation(I))
4337       return nullptr;
4338   }
4339 
4340   // Replace Op with RepOp in instruction operands.
4341   SmallVector<Value *, 8> NewOps;
4342   bool AnyReplaced = false;
4343   for (Value *InstOp : I->operands()) {
4344     if (Value *NewInstOp = simplifyWithOpsReplaced(
4345             InstOp, Ops, Q, AllowRefinement, DropFlags, MaxRecurse)) {
4346       NewOps.push_back(NewInstOp);
4347       AnyReplaced = InstOp != NewInstOp;
4348     } else {
4349       NewOps.push_back(InstOp);
4350     }
4351 
4352     // Bail out if any operand is undef and SimplifyQuery disables undef
4353     // simplification. Constant folding currently doesn't respect this option.
4354     if (isa<UndefValue>(NewOps.back()) && !Q.CanUseUndef)
4355       return nullptr;
4356   }
4357 
4358   if (!AnyReplaced)
4359     return nullptr;
4360 
4361   if (!AllowRefinement) {
4362     // General InstSimplify functions may refine the result, e.g. by returning
4363     // a constant for a potentially poison value. To avoid this, implement only
4364     // a few non-refining but profitable transforms here.
4365 
4366     if (auto *BO = dyn_cast<BinaryOperator>(I)) {
4367       unsigned Opcode = BO->getOpcode();
4368       // id op x -> x, x op id -> x
4369       // Exclude floats, because x op id may produce a different NaN value.
4370       if (!BO->getType()->isFPOrFPVectorTy()) {
4371         if (NewOps[0] == ConstantExpr::getBinOpIdentity(Opcode, I->getType()))
4372           return NewOps[1];
4373         if (NewOps[1] == ConstantExpr::getBinOpIdentity(Opcode, I->getType(),
4374                                                         /* RHS */ true))
4375           return NewOps[0];
4376       }
4377 
4378       // x & x -> x, x | x -> x
4379       if ((Opcode == Instruction::And || Opcode == Instruction::Or) &&
4380           NewOps[0] == NewOps[1]) {
4381         // or disjoint x, x results in poison.
4382         if (auto *PDI = dyn_cast<PossiblyDisjointInst>(BO)) {
4383           if (PDI->isDisjoint()) {
4384             if (!DropFlags)
4385               return nullptr;
4386             DropFlags->push_back(BO);
4387           }
4388         }
4389         return NewOps[0];
4390       }
4391 
4392       // x - x -> 0, x ^ x -> 0. This is non-refining, because x is non-poison
4393       // by assumption and this case never wraps, so nowrap flags can be
4394       // ignored.
4395       if ((Opcode == Instruction::Sub || Opcode == Instruction::Xor) &&
4396           NewOps[0] == NewOps[1] &&
4397           any_of(Ops, [=](const auto &Rep) { return NewOps[0] == Rep.second; }))
4398         return Constant::getNullValue(I->getType());
4399 
4400       // If we are substituting an absorber constant into a binop and extra
4401       // poison can't leak if we remove the select -- because both operands of
4402       // the binop are based on the same value -- then it may be safe to replace
4403       // the value with the absorber constant. Examples:
4404       // (Op == 0) ? 0 : (Op & -Op)            --> Op & -Op
4405       // (Op == 0) ? 0 : (Op * (binop Op, C))  --> Op * (binop Op, C)
4406       // (Op == -1) ? -1 : (Op | (binop C, Op) --> Op | (binop C, Op)
4407       Constant *Absorber = ConstantExpr::getBinOpAbsorber(Opcode, I->getType());
4408       if ((NewOps[0] == Absorber || NewOps[1] == Absorber) &&
4409           any_of(Ops,
4410                  [=](const auto &Rep) { return impliesPoison(BO, Rep.first); }))
4411         return Absorber;
4412     }
4413 
4414     if (isa<GetElementPtrInst>(I)) {
4415       // getelementptr x, 0 -> x.
4416       // This never returns poison, even if inbounds is set.
4417       if (NewOps.size() == 2 && match(NewOps[1], m_Zero()))
4418         return NewOps[0];
4419     }
4420   } else {
4421     // The simplification queries below may return the original value. Consider:
4422     //   %div = udiv i32 %arg, %arg2
4423     //   %mul = mul nsw i32 %div, %arg2
4424     //   %cmp = icmp eq i32 %mul, %arg
4425     //   %sel = select i1 %cmp, i32 %div, i32 undef
4426     // Replacing %arg by %mul, %div becomes "udiv i32 %mul, %arg2", which
4427     // simplifies back to %arg. This can only happen because %mul does not
4428     // dominate %div. To ensure a consistent return value contract, we make sure
4429     // that this case returns nullptr as well.
4430     auto PreventSelfSimplify = [V](Value *Simplified) {
4431       return Simplified != V ? Simplified : nullptr;
4432     };
4433 
4434     return PreventSelfSimplify(
4435         ::simplifyInstructionWithOperands(I, NewOps, Q, MaxRecurse));
4436   }
4437 
4438   // If all operands are constant after substituting Op for RepOp then we can
4439   // constant fold the instruction.
4440   SmallVector<Constant *, 8> ConstOps;
4441   for (Value *NewOp : NewOps) {
4442     if (Constant *ConstOp = dyn_cast<Constant>(NewOp))
4443       ConstOps.push_back(ConstOp);
4444     else
4445       return nullptr;
4446   }
4447 
4448   // Consider:
4449   //   %cmp = icmp eq i32 %x, 2147483647
4450   //   %add = add nsw i32 %x, 1
4451   //   %sel = select i1 %cmp, i32 -2147483648, i32 %add
4452   //
4453   // We can't replace %sel with %add unless we strip away the flags (which
4454   // will be done in InstCombine).
4455   // TODO: This may be unsound, because it only catches some forms of
4456   // refinement.
4457   if (!AllowRefinement) {
4458     if (canCreatePoison(cast<Operator>(I), !DropFlags)) {
4459       // abs cannot create poison if the value is known to never be int_min.
4460       if (auto *II = dyn_cast<IntrinsicInst>(I);
4461           II && II->getIntrinsicID() == Intrinsic::abs) {
4462         if (!ConstOps[0]->isNotMinSignedValue())
4463           return nullptr;
4464       } else
4465         return nullptr;
4466     }
4467     Constant *Res = ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI,
4468                                              /*AllowNonDeterministic=*/false);
4469     if (DropFlags && Res && I->hasPoisonGeneratingAnnotations())
4470       DropFlags->push_back(I);
4471     return Res;
4472   }
4473 
4474   return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI,
4475                                   /*AllowNonDeterministic=*/false);
4476 }
4477 
simplifyWithOpReplaced(Value * V,Value * Op,Value * RepOp,const SimplifyQuery & Q,bool AllowRefinement,SmallVectorImpl<Instruction * > * DropFlags,unsigned MaxRecurse)4478 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
4479                                      const SimplifyQuery &Q,
4480                                      bool AllowRefinement,
4481                                      SmallVectorImpl<Instruction *> *DropFlags,
4482                                      unsigned MaxRecurse) {
4483   return simplifyWithOpsReplaced(V, {{Op, RepOp}}, Q, AllowRefinement,
4484                                  DropFlags, MaxRecurse);
4485 }
4486 
simplifyWithOpReplaced(Value * V,Value * Op,Value * RepOp,const SimplifyQuery & Q,bool AllowRefinement,SmallVectorImpl<Instruction * > * DropFlags)4487 Value *llvm::simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
4488                                     const SimplifyQuery &Q,
4489                                     bool AllowRefinement,
4490                                     SmallVectorImpl<Instruction *> *DropFlags) {
4491   // If refinement is disabled, also disable undef simplifications (which are
4492   // always refinements) in SimplifyQuery.
4493   if (!AllowRefinement)
4494     return ::simplifyWithOpReplaced(V, Op, RepOp, Q.getWithoutUndef(),
4495                                     AllowRefinement, DropFlags, RecursionLimit);
4496   return ::simplifyWithOpReplaced(V, Op, RepOp, Q, AllowRefinement, DropFlags,
4497                                   RecursionLimit);
4498 }
4499 
4500 /// Try to simplify a select instruction when its condition operand is an
4501 /// integer comparison where one operand of the compare is a constant.
simplifySelectBitTest(Value * TrueVal,Value * FalseVal,Value * X,const APInt * Y,bool TrueWhenUnset)4502 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X,
4503                                     const APInt *Y, bool TrueWhenUnset) {
4504   const APInt *C;
4505 
4506   // (X & Y) == 0 ? X & ~Y : X  --> X
4507   // (X & Y) != 0 ? X & ~Y : X  --> X & ~Y
4508   if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) &&
4509       *Y == ~*C)
4510     return TrueWhenUnset ? FalseVal : TrueVal;
4511 
4512   // (X & Y) == 0 ? X : X & ~Y  --> X & ~Y
4513   // (X & Y) != 0 ? X : X & ~Y  --> X
4514   if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) &&
4515       *Y == ~*C)
4516     return TrueWhenUnset ? FalseVal : TrueVal;
4517 
4518   if (Y->isPowerOf2()) {
4519     // (X & Y) == 0 ? X | Y : X  --> X | Y
4520     // (X & Y) != 0 ? X | Y : X  --> X
4521     if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) &&
4522         *Y == *C) {
4523       // We can't return the or if it has the disjoint flag.
4524       if (TrueWhenUnset && cast<PossiblyDisjointInst>(TrueVal)->isDisjoint())
4525         return nullptr;
4526       return TrueWhenUnset ? TrueVal : FalseVal;
4527     }
4528 
4529     // (X & Y) == 0 ? X : X | Y  --> X
4530     // (X & Y) != 0 ? X : X | Y  --> X | Y
4531     if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) &&
4532         *Y == *C) {
4533       // We can't return the or if it has the disjoint flag.
4534       if (!TrueWhenUnset && cast<PossiblyDisjointInst>(FalseVal)->isDisjoint())
4535         return nullptr;
4536       return TrueWhenUnset ? TrueVal : FalseVal;
4537     }
4538   }
4539 
4540   return nullptr;
4541 }
4542 
simplifyCmpSelOfMaxMin(Value * CmpLHS,Value * CmpRHS,CmpPredicate Pred,Value * TVal,Value * FVal)4543 static Value *simplifyCmpSelOfMaxMin(Value *CmpLHS, Value *CmpRHS,
4544                                      CmpPredicate Pred, Value *TVal,
4545                                      Value *FVal) {
4546   // Canonicalize common cmp+sel operand as CmpLHS.
4547   if (CmpRHS == TVal || CmpRHS == FVal) {
4548     std::swap(CmpLHS, CmpRHS);
4549     Pred = ICmpInst::getSwappedPredicate(Pred);
4550   }
4551 
4552   // Canonicalize common cmp+sel operand as TVal.
4553   if (CmpLHS == FVal) {
4554     std::swap(TVal, FVal);
4555     Pred = ICmpInst::getInversePredicate(Pred);
4556   }
4557 
4558   // A vector select may be shuffling together elements that are equivalent
4559   // based on the max/min/select relationship.
4560   Value *X = CmpLHS, *Y = CmpRHS;
4561   bool PeekedThroughSelectShuffle = false;
4562   auto *Shuf = dyn_cast<ShuffleVectorInst>(FVal);
4563   if (Shuf && Shuf->isSelect()) {
4564     if (Shuf->getOperand(0) == Y)
4565       FVal = Shuf->getOperand(1);
4566     else if (Shuf->getOperand(1) == Y)
4567       FVal = Shuf->getOperand(0);
4568     else
4569       return nullptr;
4570     PeekedThroughSelectShuffle = true;
4571   }
4572 
4573   // (X pred Y) ? X : max/min(X, Y)
4574   auto *MMI = dyn_cast<MinMaxIntrinsic>(FVal);
4575   if (!MMI || TVal != X ||
4576       !match(FVal, m_c_MaxOrMin(m_Specific(X), m_Specific(Y))))
4577     return nullptr;
4578 
4579   // (X >  Y) ? X : max(X, Y) --> max(X, Y)
4580   // (X >= Y) ? X : max(X, Y) --> max(X, Y)
4581   // (X <  Y) ? X : min(X, Y) --> min(X, Y)
4582   // (X <= Y) ? X : min(X, Y) --> min(X, Y)
4583   //
4584   // The equivalence allows a vector select (shuffle) of max/min and Y. Ex:
4585   // (X > Y) ? X : (Z ? max(X, Y) : Y)
4586   // If Z is true, this reduces as above, and if Z is false:
4587   // (X > Y) ? X : Y --> max(X, Y)
4588   ICmpInst::Predicate MMPred = MMI->getPredicate();
4589   if (MMPred == CmpInst::getStrictPredicate(Pred))
4590     return MMI;
4591 
4592   // Other transforms are not valid with a shuffle.
4593   if (PeekedThroughSelectShuffle)
4594     return nullptr;
4595 
4596   // (X == Y) ? X : max/min(X, Y) --> max/min(X, Y)
4597   if (Pred == CmpInst::ICMP_EQ)
4598     return MMI;
4599 
4600   // (X != Y) ? X : max/min(X, Y) --> X
4601   if (Pred == CmpInst::ICMP_NE)
4602     return X;
4603 
4604   // (X <  Y) ? X : max(X, Y) --> X
4605   // (X <= Y) ? X : max(X, Y) --> X
4606   // (X >  Y) ? X : min(X, Y) --> X
4607   // (X >= Y) ? X : min(X, Y) --> X
4608   ICmpInst::Predicate InvPred = CmpInst::getInversePredicate(Pred);
4609   if (MMPred == CmpInst::getStrictPredicate(InvPred))
4610     return X;
4611 
4612   return nullptr;
4613 }
4614 
4615 /// An alternative way to test if a bit is set or not.
4616 /// uses e.g. sgt/slt or trunc instead of eq/ne.
simplifySelectWithBitTest(Value * CondVal,Value * TrueVal,Value * FalseVal)4617 static Value *simplifySelectWithBitTest(Value *CondVal, Value *TrueVal,
4618                                         Value *FalseVal) {
4619   if (auto Res = decomposeBitTest(CondVal))
4620     return simplifySelectBitTest(TrueVal, FalseVal, Res->X, &Res->Mask,
4621                                  Res->Pred == ICmpInst::ICMP_EQ);
4622 
4623   return nullptr;
4624 }
4625 
4626 /// Try to simplify a select instruction when its condition operand is an
4627 /// integer equality or floating-point equivalence comparison.
simplifySelectWithEquivalence(ArrayRef<std::pair<Value *,Value * >> Replacements,Value * TrueVal,Value * FalseVal,const SimplifyQuery & Q,unsigned MaxRecurse)4628 static Value *simplifySelectWithEquivalence(
4629     ArrayRef<std::pair<Value *, Value *>> Replacements, Value *TrueVal,
4630     Value *FalseVal, const SimplifyQuery &Q, unsigned MaxRecurse) {
4631   Value *SimplifiedFalseVal =
4632       simplifyWithOpsReplaced(FalseVal, Replacements, Q.getWithoutUndef(),
4633                               /* AllowRefinement */ false,
4634                               /* DropFlags */ nullptr, MaxRecurse);
4635   if (!SimplifiedFalseVal)
4636     SimplifiedFalseVal = FalseVal;
4637 
4638   Value *SimplifiedTrueVal =
4639       simplifyWithOpsReplaced(TrueVal, Replacements, Q,
4640                               /* AllowRefinement */ true,
4641                               /* DropFlags */ nullptr, MaxRecurse);
4642   if (!SimplifiedTrueVal)
4643     SimplifiedTrueVal = TrueVal;
4644 
4645   if (SimplifiedFalseVal == SimplifiedTrueVal)
4646     return FalseVal;
4647 
4648   return nullptr;
4649 }
4650 
4651 /// Try to simplify a select instruction when its condition operand is an
4652 /// integer comparison.
simplifySelectWithICmpCond(Value * CondVal,Value * TrueVal,Value * FalseVal,const SimplifyQuery & Q,unsigned MaxRecurse)4653 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
4654                                          Value *FalseVal,
4655                                          const SimplifyQuery &Q,
4656                                          unsigned MaxRecurse) {
4657   CmpPredicate Pred;
4658   Value *CmpLHS, *CmpRHS;
4659   if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
4660     return nullptr;
4661 
4662   if (Value *V = simplifyCmpSelOfMaxMin(CmpLHS, CmpRHS, Pred, TrueVal, FalseVal))
4663     return V;
4664 
4665   // Canonicalize ne to eq predicate.
4666   if (Pred == ICmpInst::ICMP_NE) {
4667     Pred = ICmpInst::ICMP_EQ;
4668     std::swap(TrueVal, FalseVal);
4669   }
4670 
4671   // Check for integer min/max with a limit constant:
4672   // X > MIN_INT ? X : MIN_INT --> X
4673   // X < MAX_INT ? X : MAX_INT --> X
4674   if (TrueVal->getType()->isIntOrIntVectorTy()) {
4675     Value *X, *Y;
4676     SelectPatternFlavor SPF =
4677         matchDecomposedSelectPattern(cast<ICmpInst>(CondVal), TrueVal, FalseVal,
4678                                      X, Y)
4679             .Flavor;
4680     if (SelectPatternResult::isMinOrMax(SPF) && Pred == getMinMaxPred(SPF)) {
4681       APInt LimitC = getMinMaxLimit(getInverseMinMaxFlavor(SPF),
4682                                     X->getType()->getScalarSizeInBits());
4683       if (match(Y, m_SpecificInt(LimitC)))
4684         return X;
4685     }
4686   }
4687 
4688   if (Pred == ICmpInst::ICMP_EQ && match(CmpRHS, m_Zero())) {
4689     Value *X;
4690     const APInt *Y;
4691     if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y))))
4692       if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y,
4693                                            /*TrueWhenUnset=*/true))
4694         return V;
4695 
4696     // Test for a bogus zero-shift-guard-op around funnel-shift or rotate.
4697     Value *ShAmt;
4698     auto isFsh = m_CombineOr(m_FShl(m_Value(X), m_Value(), m_Value(ShAmt)),
4699                              m_FShr(m_Value(), m_Value(X), m_Value(ShAmt)));
4700     // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X
4701     // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X
4702     if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt)
4703       return X;
4704 
4705     // Test for a zero-shift-guard-op around rotates. These are used to
4706     // avoid UB from oversized shifts in raw IR rotate patterns, but the
4707     // intrinsics do not have that problem.
4708     // We do not allow this transform for the general funnel shift case because
4709     // that would not preserve the poison safety of the original code.
4710     auto isRotate =
4711         m_CombineOr(m_FShl(m_Value(X), m_Deferred(X), m_Value(ShAmt)),
4712                     m_FShr(m_Value(X), m_Deferred(X), m_Value(ShAmt)));
4713     // (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt)
4714     // (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt)
4715     if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt &&
4716         Pred == ICmpInst::ICMP_EQ)
4717       return FalseVal;
4718 
4719     // X == 0 ? abs(X) : -abs(X) --> -abs(X)
4720     // X == 0 ? -abs(X) : abs(X) --> abs(X)
4721     if (match(TrueVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))) &&
4722         match(FalseVal, m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))))
4723       return FalseVal;
4724     if (match(TrueVal,
4725               m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) &&
4726         match(FalseVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))))
4727       return FalseVal;
4728   }
4729 
4730   // If we have a scalar equality comparison, then we know the value in one of
4731   // the arms of the select. See if substituting this value into the arm and
4732   // simplifying the result yields the same value as the other arm.
4733   if (Pred == ICmpInst::ICMP_EQ) {
4734     if (CmpLHS->getType()->isIntOrIntVectorTy() ||
4735         canReplacePointersIfEqual(CmpLHS, CmpRHS, Q.DL))
4736       if (Value *V = simplifySelectWithEquivalence({{CmpLHS, CmpRHS}}, TrueVal,
4737                                                    FalseVal, Q, MaxRecurse))
4738         return V;
4739     if (CmpLHS->getType()->isIntOrIntVectorTy() ||
4740         canReplacePointersIfEqual(CmpRHS, CmpLHS, Q.DL))
4741       if (Value *V = simplifySelectWithEquivalence({{CmpRHS, CmpLHS}}, TrueVal,
4742                                                    FalseVal, Q, MaxRecurse))
4743         return V;
4744 
4745     Value *X;
4746     Value *Y;
4747     // select((X | Y) == 0 ?  X : 0) --> 0 (commuted 2 ways)
4748     if (match(CmpLHS, m_Or(m_Value(X), m_Value(Y))) &&
4749         match(CmpRHS, m_Zero())) {
4750       // (X | Y) == 0 implies X == 0 and Y == 0.
4751       if (Value *V = simplifySelectWithEquivalence(
4752               {{X, CmpRHS}, {Y, CmpRHS}}, TrueVal, FalseVal, Q, MaxRecurse))
4753         return V;
4754     }
4755 
4756     // select((X & Y) == -1 ?  X : -1) --> -1 (commuted 2 ways)
4757     if (match(CmpLHS, m_And(m_Value(X), m_Value(Y))) &&
4758         match(CmpRHS, m_AllOnes())) {
4759       // (X & Y) == -1 implies X == -1 and Y == -1.
4760       if (Value *V = simplifySelectWithEquivalence(
4761               {{X, CmpRHS}, {Y, CmpRHS}}, TrueVal, FalseVal, Q, MaxRecurse))
4762         return V;
4763     }
4764   }
4765 
4766   return nullptr;
4767 }
4768 
4769 /// Try to simplify a select instruction when its condition operand is a
4770 /// floating-point comparison.
simplifySelectWithFCmp(Value * Cond,Value * T,Value * F,const SimplifyQuery & Q,unsigned MaxRecurse)4771 static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F,
4772                                      const SimplifyQuery &Q,
4773                                      unsigned MaxRecurse) {
4774   CmpPredicate Pred;
4775   Value *CmpLHS, *CmpRHS;
4776   if (!match(Cond, m_FCmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
4777     return nullptr;
4778   FCmpInst *I = cast<FCmpInst>(Cond);
4779 
4780   bool IsEquiv = I->isEquivalence();
4781   if (I->isEquivalence(/*Invert=*/true)) {
4782     std::swap(T, F);
4783     Pred = FCmpInst::getInversePredicate(Pred);
4784     IsEquiv = true;
4785   }
4786 
4787   // This transforms is safe if at least one operand is known to not be zero.
4788   // Otherwise, the select can change the sign of a zero operand.
4789   if (IsEquiv) {
4790     if (Value *V = simplifySelectWithEquivalence({{CmpLHS, CmpRHS}}, T, F, Q,
4791                                                  MaxRecurse))
4792       return V;
4793     if (Value *V = simplifySelectWithEquivalence({{CmpRHS, CmpLHS}}, T, F, Q,
4794                                                  MaxRecurse))
4795       return V;
4796   }
4797 
4798   // Canonicalize CmpLHS to be T, and CmpRHS to be F, if they're swapped.
4799   if (CmpLHS == F && CmpRHS == T)
4800     std::swap(CmpLHS, CmpRHS);
4801 
4802   if (CmpLHS != T || CmpRHS != F)
4803     return nullptr;
4804 
4805   // This transform is also safe if we do not have (do not care about) -0.0.
4806   if (Q.CxtI && isa<FPMathOperator>(Q.CxtI) && Q.CxtI->hasNoSignedZeros()) {
4807     // (T == F) ? T : F --> F
4808     if (Pred == FCmpInst::FCMP_OEQ)
4809       return F;
4810 
4811     // (T != F) ? T : F --> T
4812     if (Pred == FCmpInst::FCMP_UNE)
4813       return T;
4814   }
4815 
4816   return nullptr;
4817 }
4818 
4819 /// Given operands for a SelectInst, see if we can fold the result.
4820 /// If not, this returns null.
simplifySelectInst(Value * Cond,Value * TrueVal,Value * FalseVal,const SimplifyQuery & Q,unsigned MaxRecurse)4821 static Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
4822                                  const SimplifyQuery &Q, unsigned MaxRecurse) {
4823   if (auto *CondC = dyn_cast<Constant>(Cond)) {
4824     if (auto *TrueC = dyn_cast<Constant>(TrueVal))
4825       if (auto *FalseC = dyn_cast<Constant>(FalseVal))
4826         if (Constant *C = ConstantFoldSelectInstruction(CondC, TrueC, FalseC))
4827           return C;
4828 
4829     // select poison, X, Y -> poison
4830     if (isa<PoisonValue>(CondC))
4831       return PoisonValue::get(TrueVal->getType());
4832 
4833     // select undef, X, Y -> X or Y
4834     if (Q.isUndefValue(CondC))
4835       return isa<Constant>(FalseVal) ? FalseVal : TrueVal;
4836 
4837     // select true,  X, Y --> X
4838     // select false, X, Y --> Y
4839     // For vectors, allow undef/poison elements in the condition to match the
4840     // defined elements, so we can eliminate the select.
4841     if (match(CondC, m_One()))
4842       return TrueVal;
4843     if (match(CondC, m_Zero()))
4844       return FalseVal;
4845   }
4846 
4847   assert(Cond->getType()->isIntOrIntVectorTy(1) &&
4848          "Select must have bool or bool vector condition");
4849   assert(TrueVal->getType() == FalseVal->getType() &&
4850          "Select must have same types for true/false ops");
4851 
4852   if (Cond->getType() == TrueVal->getType()) {
4853     // select i1 Cond, i1 true, i1 false --> i1 Cond
4854     if (match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt()))
4855       return Cond;
4856 
4857     // (X && Y) ? X : Y --> Y (commuted 2 ways)
4858     if (match(Cond, m_c_LogicalAnd(m_Specific(TrueVal), m_Specific(FalseVal))))
4859       return FalseVal;
4860 
4861     // (X || Y) ? X : Y --> X (commuted 2 ways)
4862     if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Specific(FalseVal))))
4863       return TrueVal;
4864 
4865     // (X || Y) ? false : X --> false (commuted 2 ways)
4866     if (match(Cond, m_c_LogicalOr(m_Specific(FalseVal), m_Value())) &&
4867         match(TrueVal, m_ZeroInt()))
4868       return ConstantInt::getFalse(Cond->getType());
4869 
4870     // Match patterns that end in logical-and.
4871     if (match(FalseVal, m_ZeroInt())) {
4872       // !(X || Y) && X --> false (commuted 2 ways)
4873       if (match(Cond, m_Not(m_c_LogicalOr(m_Specific(TrueVal), m_Value()))))
4874         return ConstantInt::getFalse(Cond->getType());
4875       // X && !(X || Y) --> false (commuted 2 ways)
4876       if (match(TrueVal, m_Not(m_c_LogicalOr(m_Specific(Cond), m_Value()))))
4877         return ConstantInt::getFalse(Cond->getType());
4878 
4879       // (X || Y) && Y --> Y (commuted 2 ways)
4880       if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Value())))
4881         return TrueVal;
4882       // Y && (X || Y) --> Y (commuted 2 ways)
4883       if (match(TrueVal, m_c_LogicalOr(m_Specific(Cond), m_Value())))
4884         return Cond;
4885 
4886       // (X || Y) && (X || !Y) --> X (commuted 8 ways)
4887       Value *X, *Y;
4888       if (match(Cond, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) &&
4889           match(TrueVal, m_c_LogicalOr(m_Specific(X), m_Specific(Y))))
4890         return X;
4891       if (match(TrueVal, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) &&
4892           match(Cond, m_c_LogicalOr(m_Specific(X), m_Specific(Y))))
4893         return X;
4894     }
4895 
4896     // Match patterns that end in logical-or.
4897     if (match(TrueVal, m_One())) {
4898       // !(X && Y) || X --> true (commuted 2 ways)
4899       if (match(Cond, m_Not(m_c_LogicalAnd(m_Specific(FalseVal), m_Value()))))
4900         return ConstantInt::getTrue(Cond->getType());
4901       // X || !(X && Y) --> true (commuted 2 ways)
4902       if (match(FalseVal, m_Not(m_c_LogicalAnd(m_Specific(Cond), m_Value()))))
4903         return ConstantInt::getTrue(Cond->getType());
4904 
4905       // (X && Y) || Y --> Y (commuted 2 ways)
4906       if (match(Cond, m_c_LogicalAnd(m_Specific(FalseVal), m_Value())))
4907         return FalseVal;
4908       // Y || (X && Y) --> Y (commuted 2 ways)
4909       if (match(FalseVal, m_c_LogicalAnd(m_Specific(Cond), m_Value())))
4910         return Cond;
4911     }
4912   }
4913 
4914   // select ?, X, X -> X
4915   if (TrueVal == FalseVal)
4916     return TrueVal;
4917 
4918   if (Cond == TrueVal) {
4919     // select i1 X, i1 X, i1 false --> X (logical-and)
4920     if (match(FalseVal, m_ZeroInt()))
4921       return Cond;
4922     // select i1 X, i1 X, i1 true --> true
4923     if (match(FalseVal, m_One()))
4924       return ConstantInt::getTrue(Cond->getType());
4925   }
4926   if (Cond == FalseVal) {
4927     // select i1 X, i1 true, i1 X --> X (logical-or)
4928     if (match(TrueVal, m_One()))
4929       return Cond;
4930     // select i1 X, i1 false, i1 X --> false
4931     if (match(TrueVal, m_ZeroInt()))
4932       return ConstantInt::getFalse(Cond->getType());
4933   }
4934 
4935   // If the true or false value is poison, we can fold to the other value.
4936   // If the true or false value is undef, we can fold to the other value as
4937   // long as the other value isn't poison.
4938   // select ?, poison, X -> X
4939   // select ?, undef,  X -> X
4940   if (isa<PoisonValue>(TrueVal) ||
4941       (Q.isUndefValue(TrueVal) && impliesPoison(FalseVal, Cond)))
4942     return FalseVal;
4943   // select ?, X, poison -> X
4944   // select ?, X, undef  -> X
4945   if (isa<PoisonValue>(FalseVal) ||
4946       (Q.isUndefValue(FalseVal) && impliesPoison(TrueVal, Cond)))
4947     return TrueVal;
4948 
4949   // Deal with partial undef vector constants: select ?, VecC, VecC' --> VecC''
4950   Constant *TrueC, *FalseC;
4951   if (isa<FixedVectorType>(TrueVal->getType()) &&
4952       match(TrueVal, m_Constant(TrueC)) &&
4953       match(FalseVal, m_Constant(FalseC))) {
4954     unsigned NumElts =
4955         cast<FixedVectorType>(TrueC->getType())->getNumElements();
4956     SmallVector<Constant *, 16> NewC;
4957     for (unsigned i = 0; i != NumElts; ++i) {
4958       // Bail out on incomplete vector constants.
4959       Constant *TEltC = TrueC->getAggregateElement(i);
4960       Constant *FEltC = FalseC->getAggregateElement(i);
4961       if (!TEltC || !FEltC)
4962         break;
4963 
4964       // If the elements match (undef or not), that value is the result. If only
4965       // one element is undef, choose the defined element as the safe result.
4966       if (TEltC == FEltC)
4967         NewC.push_back(TEltC);
4968       else if (isa<PoisonValue>(TEltC) ||
4969                (Q.isUndefValue(TEltC) && isGuaranteedNotToBePoison(FEltC)))
4970         NewC.push_back(FEltC);
4971       else if (isa<PoisonValue>(FEltC) ||
4972                (Q.isUndefValue(FEltC) && isGuaranteedNotToBePoison(TEltC)))
4973         NewC.push_back(TEltC);
4974       else
4975         break;
4976     }
4977     if (NewC.size() == NumElts)
4978       return ConstantVector::get(NewC);
4979   }
4980 
4981   if (Value *V =
4982           simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse))
4983     return V;
4984 
4985   if (Value *V = simplifySelectWithBitTest(Cond, TrueVal, FalseVal))
4986     return V;
4987 
4988   if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q, MaxRecurse))
4989     return V;
4990 
4991   std::optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL);
4992   if (Imp)
4993     return *Imp ? TrueVal : FalseVal;
4994 
4995   return nullptr;
4996 }
4997 
simplifySelectInst(Value * Cond,Value * TrueVal,Value * FalseVal,const SimplifyQuery & Q)4998 Value *llvm::simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
4999                                 const SimplifyQuery &Q) {
5000   return ::simplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit);
5001 }
5002 
5003 /// Given operands for an GetElementPtrInst, see if we can fold the result.
5004 /// If not, this returns null.
simplifyGEPInst(Type * SrcTy,Value * Ptr,ArrayRef<Value * > Indices,GEPNoWrapFlags NW,const SimplifyQuery & Q,unsigned)5005 static Value *simplifyGEPInst(Type *SrcTy, Value *Ptr,
5006                               ArrayRef<Value *> Indices, GEPNoWrapFlags NW,
5007                               const SimplifyQuery &Q, unsigned) {
5008   // The type of the GEP pointer operand.
5009   unsigned AS =
5010       cast<PointerType>(Ptr->getType()->getScalarType())->getAddressSpace();
5011 
5012   // getelementptr P -> P.
5013   if (Indices.empty())
5014     return Ptr;
5015 
5016   // Compute the (pointer) type returned by the GEP instruction.
5017   Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Indices);
5018   Type *GEPTy = Ptr->getType();
5019   if (!GEPTy->isVectorTy()) {
5020     for (Value *Op : Indices) {
5021       // If one of the operands is a vector, the result type is a vector of
5022       // pointers. All vector operands must have the same number of elements.
5023       if (VectorType *VT = dyn_cast<VectorType>(Op->getType())) {
5024         GEPTy = VectorType::get(GEPTy, VT->getElementCount());
5025         break;
5026       }
5027     }
5028   }
5029 
5030   // All-zero GEP is a no-op, unless it performs a vector splat.
5031   if (Ptr->getType() == GEPTy &&
5032       all_of(Indices, [](const auto *V) { return match(V, m_Zero()); }))
5033     return Ptr;
5034 
5035   // getelementptr poison, idx -> poison
5036   // getelementptr baseptr, poison -> poison
5037   if (isa<PoisonValue>(Ptr) ||
5038       any_of(Indices, [](const auto *V) { return isa<PoisonValue>(V); }))
5039     return PoisonValue::get(GEPTy);
5040 
5041   // getelementptr undef, idx -> undef
5042   if (Q.isUndefValue(Ptr))
5043     return UndefValue::get(GEPTy);
5044 
5045   bool IsScalableVec =
5046       SrcTy->isScalableTy() || any_of(Indices, [](const Value *V) {
5047         return isa<ScalableVectorType>(V->getType());
5048       });
5049 
5050   if (Indices.size() == 1) {
5051     Type *Ty = SrcTy;
5052     if (!IsScalableVec && Ty->isSized()) {
5053       Value *P;
5054       uint64_t C;
5055       uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty);
5056       // getelementptr P, N -> P if P points to a type of zero size.
5057       if (TyAllocSize == 0 && Ptr->getType() == GEPTy)
5058         return Ptr;
5059 
5060       // The following transforms are only safe if the ptrtoint cast
5061       // doesn't truncate the pointers.
5062       if (Indices[0]->getType()->getScalarSizeInBits() ==
5063           Q.DL.getPointerSizeInBits(AS)) {
5064         auto CanSimplify = [GEPTy, &P, Ptr]() -> bool {
5065           return P->getType() == GEPTy &&
5066                  getUnderlyingObject(P) == getUnderlyingObject(Ptr);
5067         };
5068         // getelementptr V, (sub P, V) -> P if P points to a type of size 1.
5069         if (TyAllocSize == 1 &&
5070             match(Indices[0],
5071                   m_Sub(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Specific(Ptr)))) &&
5072             CanSimplify())
5073           return P;
5074 
5075         // getelementptr V, (ashr (sub P, V), C) -> P if P points to a type of
5076         // size 1 << C.
5077         if (match(Indices[0], m_AShr(m_Sub(m_PtrToInt(m_Value(P)),
5078                                            m_PtrToInt(m_Specific(Ptr))),
5079                                      m_ConstantInt(C))) &&
5080             TyAllocSize == 1ULL << C && CanSimplify())
5081           return P;
5082 
5083         // getelementptr V, (sdiv (sub P, V), C) -> P if P points to a type of
5084         // size C.
5085         if (match(Indices[0], m_SDiv(m_Sub(m_PtrToInt(m_Value(P)),
5086                                            m_PtrToInt(m_Specific(Ptr))),
5087                                      m_SpecificInt(TyAllocSize))) &&
5088             CanSimplify())
5089           return P;
5090       }
5091     }
5092   }
5093 
5094   if (!IsScalableVec && Q.DL.getTypeAllocSize(LastType) == 1 &&
5095       all_of(Indices.drop_back(1),
5096              [](Value *Idx) { return match(Idx, m_Zero()); })) {
5097     unsigned IdxWidth =
5098         Q.DL.getIndexSizeInBits(Ptr->getType()->getPointerAddressSpace());
5099     if (Q.DL.getTypeSizeInBits(Indices.back()->getType()) == IdxWidth) {
5100       APInt BasePtrOffset(IdxWidth, 0);
5101       Value *StrippedBasePtr =
5102           Ptr->stripAndAccumulateInBoundsConstantOffsets(Q.DL, BasePtrOffset);
5103 
5104       // Avoid creating inttoptr of zero here: While LLVMs treatment of
5105       // inttoptr is generally conservative, this particular case is folded to
5106       // a null pointer, which will have incorrect provenance.
5107 
5108       // gep (gep V, C), (sub 0, V) -> C
5109       if (match(Indices.back(),
5110                 m_Neg(m_PtrToInt(m_Specific(StrippedBasePtr)))) &&
5111           !BasePtrOffset.isZero()) {
5112         auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset);
5113         return ConstantExpr::getIntToPtr(CI, GEPTy);
5114       }
5115       // gep (gep V, C), (xor V, -1) -> C-1
5116       if (match(Indices.back(),
5117                 m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes())) &&
5118           !BasePtrOffset.isOne()) {
5119         auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1);
5120         return ConstantExpr::getIntToPtr(CI, GEPTy);
5121       }
5122     }
5123   }
5124 
5125   // Check to see if this is constant foldable.
5126   if (!isa<Constant>(Ptr) ||
5127       !all_of(Indices, [](Value *V) { return isa<Constant>(V); }))
5128     return nullptr;
5129 
5130   if (!ConstantExpr::isSupportedGetElementPtr(SrcTy))
5131     return ConstantFoldGetElementPtr(SrcTy, cast<Constant>(Ptr), std::nullopt,
5132                                      Indices);
5133 
5134   auto *CE =
5135       ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ptr), Indices, NW);
5136   return ConstantFoldConstant(CE, Q.DL);
5137 }
5138 
simplifyGEPInst(Type * SrcTy,Value * Ptr,ArrayRef<Value * > Indices,GEPNoWrapFlags NW,const SimplifyQuery & Q)5139 Value *llvm::simplifyGEPInst(Type *SrcTy, Value *Ptr, ArrayRef<Value *> Indices,
5140                              GEPNoWrapFlags NW, const SimplifyQuery &Q) {
5141   return ::simplifyGEPInst(SrcTy, Ptr, Indices, NW, Q, RecursionLimit);
5142 }
5143 
5144 /// Given operands for an InsertValueInst, see if we can fold the result.
5145 /// If not, this returns null.
simplifyInsertValueInst(Value * Agg,Value * Val,ArrayRef<unsigned> Idxs,const SimplifyQuery & Q,unsigned)5146 static Value *simplifyInsertValueInst(Value *Agg, Value *Val,
5147                                       ArrayRef<unsigned> Idxs,
5148                                       const SimplifyQuery &Q, unsigned) {
5149   if (Constant *CAgg = dyn_cast<Constant>(Agg))
5150     if (Constant *CVal = dyn_cast<Constant>(Val))
5151       return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
5152 
5153   // insertvalue x, poison, n -> x
5154   // insertvalue x, undef, n -> x if x cannot be poison
5155   if (isa<PoisonValue>(Val) ||
5156       (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Agg)))
5157     return Agg;
5158 
5159   // insertvalue x, (extractvalue y, n), n
5160   if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
5161     if (EV->getAggregateOperand()->getType() == Agg->getType() &&
5162         EV->getIndices() == Idxs) {
5163       // insertvalue poison, (extractvalue y, n), n -> y
5164       // insertvalue undef, (extractvalue y, n), n -> y if y cannot be poison
5165       if (isa<PoisonValue>(Agg) ||
5166           (Q.isUndefValue(Agg) &&
5167            isGuaranteedNotToBePoison(EV->getAggregateOperand())))
5168         return EV->getAggregateOperand();
5169 
5170       // insertvalue y, (extractvalue y, n), n -> y
5171       if (Agg == EV->getAggregateOperand())
5172         return Agg;
5173     }
5174 
5175   return nullptr;
5176 }
5177 
simplifyInsertValueInst(Value * Agg,Value * Val,ArrayRef<unsigned> Idxs,const SimplifyQuery & Q)5178 Value *llvm::simplifyInsertValueInst(Value *Agg, Value *Val,
5179                                      ArrayRef<unsigned> Idxs,
5180                                      const SimplifyQuery &Q) {
5181   return ::simplifyInsertValueInst(Agg, Val, Idxs, Q, RecursionLimit);
5182 }
5183 
simplifyInsertElementInst(Value * Vec,Value * Val,Value * Idx,const SimplifyQuery & Q)5184 Value *llvm::simplifyInsertElementInst(Value *Vec, Value *Val, Value *Idx,
5185                                        const SimplifyQuery &Q) {
5186   // Try to constant fold.
5187   auto *VecC = dyn_cast<Constant>(Vec);
5188   auto *ValC = dyn_cast<Constant>(Val);
5189   auto *IdxC = dyn_cast<Constant>(Idx);
5190   if (VecC && ValC && IdxC)
5191     return ConstantExpr::getInsertElement(VecC, ValC, IdxC);
5192 
5193   // For fixed-length vector, fold into poison if index is out of bounds.
5194   if (auto *CI = dyn_cast<ConstantInt>(Idx)) {
5195     if (isa<FixedVectorType>(Vec->getType()) &&
5196         CI->uge(cast<FixedVectorType>(Vec->getType())->getNumElements()))
5197       return PoisonValue::get(Vec->getType());
5198   }
5199 
5200   // If index is undef, it might be out of bounds (see above case)
5201   if (Q.isUndefValue(Idx))
5202     return PoisonValue::get(Vec->getType());
5203 
5204   // If the scalar is poison, or it is undef and there is no risk of
5205   // propagating poison from the vector value, simplify to the vector value.
5206   if (isa<PoisonValue>(Val) ||
5207       (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Vec)))
5208     return Vec;
5209 
5210   // Inserting the splatted value into a constant splat does nothing.
5211   if (VecC && ValC && VecC->getSplatValue() == ValC)
5212     return Vec;
5213 
5214   // If we are extracting a value from a vector, then inserting it into the same
5215   // place, that's the input vector:
5216   // insertelt Vec, (extractelt Vec, Idx), Idx --> Vec
5217   if (match(Val, m_ExtractElt(m_Specific(Vec), m_Specific(Idx))))
5218     return Vec;
5219 
5220   return nullptr;
5221 }
5222 
5223 /// Given operands for an ExtractValueInst, see if we can fold the result.
5224 /// If not, this returns null.
simplifyExtractValueInst(Value * Agg,ArrayRef<unsigned> Idxs,const SimplifyQuery &,unsigned)5225 static Value *simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
5226                                        const SimplifyQuery &, unsigned) {
5227   if (auto *CAgg = dyn_cast<Constant>(Agg))
5228     return ConstantFoldExtractValueInstruction(CAgg, Idxs);
5229 
5230   // extractvalue x, (insertvalue y, elt, n), n -> elt
5231   unsigned NumIdxs = Idxs.size();
5232   for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr;
5233        IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) {
5234     ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices();
5235     unsigned NumInsertValueIdxs = InsertValueIdxs.size();
5236     unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs);
5237     if (InsertValueIdxs.slice(0, NumCommonIdxs) ==
5238         Idxs.slice(0, NumCommonIdxs)) {
5239       if (NumIdxs == NumInsertValueIdxs)
5240         return IVI->getInsertedValueOperand();
5241       break;
5242     }
5243   }
5244 
5245   return nullptr;
5246 }
5247 
simplifyExtractValueInst(Value * Agg,ArrayRef<unsigned> Idxs,const SimplifyQuery & Q)5248 Value *llvm::simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
5249                                       const SimplifyQuery &Q) {
5250   return ::simplifyExtractValueInst(Agg, Idxs, Q, RecursionLimit);
5251 }
5252 
5253 /// Given operands for an ExtractElementInst, see if we can fold the result.
5254 /// If not, this returns null.
simplifyExtractElementInst(Value * Vec,Value * Idx,const SimplifyQuery & Q,unsigned)5255 static Value *simplifyExtractElementInst(Value *Vec, Value *Idx,
5256                                          const SimplifyQuery &Q, unsigned) {
5257   auto *VecVTy = cast<VectorType>(Vec->getType());
5258   if (auto *CVec = dyn_cast<Constant>(Vec)) {
5259     if (auto *CIdx = dyn_cast<Constant>(Idx))
5260       return ConstantExpr::getExtractElement(CVec, CIdx);
5261 
5262     if (Q.isUndefValue(Vec))
5263       return UndefValue::get(VecVTy->getElementType());
5264   }
5265 
5266   // An undef extract index can be arbitrarily chosen to be an out-of-range
5267   // index value, which would result in the instruction being poison.
5268   if (Q.isUndefValue(Idx))
5269     return PoisonValue::get(VecVTy->getElementType());
5270 
5271   // If extracting a specified index from the vector, see if we can recursively
5272   // find a previously computed scalar that was inserted into the vector.
5273   if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) {
5274     // For fixed-length vector, fold into undef if index is out of bounds.
5275     unsigned MinNumElts = VecVTy->getElementCount().getKnownMinValue();
5276     if (isa<FixedVectorType>(VecVTy) && IdxC->getValue().uge(MinNumElts))
5277       return PoisonValue::get(VecVTy->getElementType());
5278     // Handle case where an element is extracted from a splat.
5279     if (IdxC->getValue().ult(MinNumElts))
5280       if (auto *Splat = getSplatValue(Vec))
5281         return Splat;
5282     if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
5283       return Elt;
5284   } else {
5285     // extractelt x, (insertelt y, elt, n), n -> elt
5286     // If the possibly-variable indices are trivially known to be equal
5287     // (because they are the same operand) then use the value that was
5288     // inserted directly.
5289     auto *IE = dyn_cast<InsertElementInst>(Vec);
5290     if (IE && IE->getOperand(2) == Idx)
5291       return IE->getOperand(1);
5292 
5293     // The index is not relevant if our vector is a splat.
5294     if (Value *Splat = getSplatValue(Vec))
5295       return Splat;
5296   }
5297   return nullptr;
5298 }
5299 
simplifyExtractElementInst(Value * Vec,Value * Idx,const SimplifyQuery & Q)5300 Value *llvm::simplifyExtractElementInst(Value *Vec, Value *Idx,
5301                                         const SimplifyQuery &Q) {
5302   return ::simplifyExtractElementInst(Vec, Idx, Q, RecursionLimit);
5303 }
5304 
5305 /// See if we can fold the given phi. If not, returns null.
simplifyPHINode(PHINode * PN,ArrayRef<Value * > IncomingValues,const SimplifyQuery & Q)5306 static Value *simplifyPHINode(PHINode *PN, ArrayRef<Value *> IncomingValues,
5307                               const SimplifyQuery &Q) {
5308   // WARNING: no matter how worthwhile it may seem, we can not perform PHI CSE
5309   //          here, because the PHI we may succeed simplifying to was not
5310   //          def-reachable from the original PHI!
5311 
5312   // If all of the PHI's incoming values are the same then replace the PHI node
5313   // with the common value.
5314   Value *CommonValue = nullptr;
5315   bool HasPoisonInput = false;
5316   bool HasUndefInput = false;
5317   for (Value *Incoming : IncomingValues) {
5318     // If the incoming value is the phi node itself, it can safely be skipped.
5319     if (Incoming == PN)
5320       continue;
5321     if (isa<PoisonValue>(Incoming)) {
5322       HasPoisonInput = true;
5323       continue;
5324     }
5325     if (Q.isUndefValue(Incoming)) {
5326       // Remember that we saw an undef value, but otherwise ignore them.
5327       HasUndefInput = true;
5328       continue;
5329     }
5330     if (CommonValue && Incoming != CommonValue)
5331       return nullptr; // Not the same, bail out.
5332     CommonValue = Incoming;
5333   }
5334 
5335   // If CommonValue is null then all of the incoming values were either undef,
5336   // poison or equal to the phi node itself.
5337   if (!CommonValue)
5338     return HasUndefInput ? UndefValue::get(PN->getType())
5339                          : PoisonValue::get(PN->getType());
5340 
5341   if (HasPoisonInput || HasUndefInput) {
5342     // If we have a PHI node like phi(X, undef, X), where X is defined by some
5343     // instruction, we cannot return X as the result of the PHI node unless it
5344     // dominates the PHI block.
5345     if (!valueDominatesPHI(CommonValue, PN, Q.DT))
5346       return nullptr;
5347 
5348     // Make sure we do not replace an undef value with poison.
5349     if (HasUndefInput &&
5350         !isGuaranteedNotToBePoison(CommonValue, Q.AC, Q.CxtI, Q.DT))
5351       return nullptr;
5352     return CommonValue;
5353   }
5354 
5355   return CommonValue;
5356 }
5357 
simplifyCastInst(unsigned CastOpc,Value * Op,Type * Ty,const SimplifyQuery & Q,unsigned MaxRecurse)5358 static Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
5359                                const SimplifyQuery &Q, unsigned MaxRecurse) {
5360   if (auto *C = dyn_cast<Constant>(Op))
5361     return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL);
5362 
5363   if (auto *CI = dyn_cast<CastInst>(Op)) {
5364     auto *Src = CI->getOperand(0);
5365     Type *SrcTy = Src->getType();
5366     Type *MidTy = CI->getType();
5367     Type *DstTy = Ty;
5368     if (Src->getType() == Ty) {
5369       auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode());
5370       auto SecondOp = static_cast<Instruction::CastOps>(CastOpc);
5371       Type *SrcIntPtrTy =
5372           SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr;
5373       Type *MidIntPtrTy =
5374           MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr;
5375       Type *DstIntPtrTy =
5376           DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr;
5377       if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy,
5378                                          SrcIntPtrTy, MidIntPtrTy,
5379                                          DstIntPtrTy) == Instruction::BitCast)
5380         return Src;
5381     }
5382   }
5383 
5384   // bitcast x -> x
5385   if (CastOpc == Instruction::BitCast)
5386     if (Op->getType() == Ty)
5387       return Op;
5388 
5389   // ptrtoint (ptradd (Ptr, X - ptrtoint(Ptr))) -> X
5390   Value *Ptr, *X;
5391   if (CastOpc == Instruction::PtrToInt &&
5392       match(Op, m_PtrAdd(m_Value(Ptr),
5393                          m_Sub(m_Value(X), m_PtrToInt(m_Deferred(Ptr))))) &&
5394       X->getType() == Ty && Ty == Q.DL.getIndexType(Ptr->getType()))
5395     return X;
5396 
5397   return nullptr;
5398 }
5399 
simplifyCastInst(unsigned CastOpc,Value * Op,Type * Ty,const SimplifyQuery & Q)5400 Value *llvm::simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
5401                               const SimplifyQuery &Q) {
5402   return ::simplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit);
5403 }
5404 
5405 /// For the given destination element of a shuffle, peek through shuffles to
5406 /// match a root vector source operand that contains that element in the same
5407 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s).
foldIdentityShuffles(int DestElt,Value * Op0,Value * Op1,int MaskVal,Value * RootVec,unsigned MaxRecurse)5408 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1,
5409                                    int MaskVal, Value *RootVec,
5410                                    unsigned MaxRecurse) {
5411   if (!MaxRecurse--)
5412     return nullptr;
5413 
5414   // Bail out if any mask value is undefined. That kind of shuffle may be
5415   // simplified further based on demanded bits or other folds.
5416   if (MaskVal == -1)
5417     return nullptr;
5418 
5419   // The mask value chooses which source operand we need to look at next.
5420   int InVecNumElts = cast<FixedVectorType>(Op0->getType())->getNumElements();
5421   int RootElt = MaskVal;
5422   Value *SourceOp = Op0;
5423   if (MaskVal >= InVecNumElts) {
5424     RootElt = MaskVal - InVecNumElts;
5425     SourceOp = Op1;
5426   }
5427 
5428   // If the source operand is a shuffle itself, look through it to find the
5429   // matching root vector.
5430   if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) {
5431     return foldIdentityShuffles(
5432         DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1),
5433         SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse);
5434   }
5435 
5436   // The source operand is not a shuffle. Initialize the root vector value for
5437   // this shuffle if that has not been done yet.
5438   if (!RootVec)
5439     RootVec = SourceOp;
5440 
5441   // Give up as soon as a source operand does not match the existing root value.
5442   if (RootVec != SourceOp)
5443     return nullptr;
5444 
5445   // The element must be coming from the same lane in the source vector
5446   // (although it may have crossed lanes in intermediate shuffles).
5447   if (RootElt != DestElt)
5448     return nullptr;
5449 
5450   return RootVec;
5451 }
5452 
simplifyShuffleVectorInst(Value * Op0,Value * Op1,ArrayRef<int> Mask,Type * RetTy,const SimplifyQuery & Q,unsigned MaxRecurse)5453 static Value *simplifyShuffleVectorInst(Value *Op0, Value *Op1,
5454                                         ArrayRef<int> Mask, Type *RetTy,
5455                                         const SimplifyQuery &Q,
5456                                         unsigned MaxRecurse) {
5457   if (all_of(Mask, [](int Elem) { return Elem == PoisonMaskElem; }))
5458     return PoisonValue::get(RetTy);
5459 
5460   auto *InVecTy = cast<VectorType>(Op0->getType());
5461   unsigned MaskNumElts = Mask.size();
5462   ElementCount InVecEltCount = InVecTy->getElementCount();
5463 
5464   bool Scalable = InVecEltCount.isScalable();
5465 
5466   SmallVector<int, 32> Indices;
5467   Indices.assign(Mask.begin(), Mask.end());
5468 
5469   // Canonicalization: If mask does not select elements from an input vector,
5470   // replace that input vector with poison.
5471   if (!Scalable) {
5472     bool MaskSelects0 = false, MaskSelects1 = false;
5473     unsigned InVecNumElts = InVecEltCount.getKnownMinValue();
5474     for (unsigned i = 0; i != MaskNumElts; ++i) {
5475       if (Indices[i] == -1)
5476         continue;
5477       if ((unsigned)Indices[i] < InVecNumElts)
5478         MaskSelects0 = true;
5479       else
5480         MaskSelects1 = true;
5481     }
5482     if (!MaskSelects0)
5483       Op0 = PoisonValue::get(InVecTy);
5484     if (!MaskSelects1)
5485       Op1 = PoisonValue::get(InVecTy);
5486   }
5487 
5488   auto *Op0Const = dyn_cast<Constant>(Op0);
5489   auto *Op1Const = dyn_cast<Constant>(Op1);
5490 
5491   // If all operands are constant, constant fold the shuffle. This
5492   // transformation depends on the value of the mask which is not known at
5493   // compile time for scalable vectors
5494   if (Op0Const && Op1Const)
5495     return ConstantExpr::getShuffleVector(Op0Const, Op1Const, Mask);
5496 
5497   // Canonicalization: if only one input vector is constant, it shall be the
5498   // second one. This transformation depends on the value of the mask which
5499   // is not known at compile time for scalable vectors
5500   if (!Scalable && Op0Const && !Op1Const) {
5501     std::swap(Op0, Op1);
5502     ShuffleVectorInst::commuteShuffleMask(Indices,
5503                                           InVecEltCount.getKnownMinValue());
5504   }
5505 
5506   // A splat of an inserted scalar constant becomes a vector constant:
5507   // shuf (inselt ?, C, IndexC), undef, <IndexC, IndexC...> --> <C, C...>
5508   // NOTE: We may have commuted above, so analyze the updated Indices, not the
5509   //       original mask constant.
5510   // NOTE: This transformation depends on the value of the mask which is not
5511   // known at compile time for scalable vectors
5512   Constant *C;
5513   ConstantInt *IndexC;
5514   if (!Scalable && match(Op0, m_InsertElt(m_Value(), m_Constant(C),
5515                                           m_ConstantInt(IndexC)))) {
5516     // Match a splat shuffle mask of the insert index allowing undef elements.
5517     int InsertIndex = IndexC->getZExtValue();
5518     if (all_of(Indices, [InsertIndex](int MaskElt) {
5519           return MaskElt == InsertIndex || MaskElt == -1;
5520         })) {
5521       assert(isa<UndefValue>(Op1) && "Expected undef operand 1 for splat");
5522 
5523       // Shuffle mask poisons become poison constant result elements.
5524       SmallVector<Constant *, 16> VecC(MaskNumElts, C);
5525       for (unsigned i = 0; i != MaskNumElts; ++i)
5526         if (Indices[i] == -1)
5527           VecC[i] = PoisonValue::get(C->getType());
5528       return ConstantVector::get(VecC);
5529     }
5530   }
5531 
5532   // A shuffle of a splat is always the splat itself. Legal if the shuffle's
5533   // value type is same as the input vectors' type.
5534   if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0))
5535     if (Q.isUndefValue(Op1) && RetTy == InVecTy &&
5536         all_equal(OpShuf->getShuffleMask()))
5537       return Op0;
5538 
5539   // All remaining transformation depend on the value of the mask, which is
5540   // not known at compile time for scalable vectors.
5541   if (Scalable)
5542     return nullptr;
5543 
5544   // Don't fold a shuffle with undef mask elements. This may get folded in a
5545   // better way using demanded bits or other analysis.
5546   // TODO: Should we allow this?
5547   if (is_contained(Indices, -1))
5548     return nullptr;
5549 
5550   // Check if every element of this shuffle can be mapped back to the
5551   // corresponding element of a single root vector. If so, we don't need this
5552   // shuffle. This handles simple identity shuffles as well as chains of
5553   // shuffles that may widen/narrow and/or move elements across lanes and back.
5554   Value *RootVec = nullptr;
5555   for (unsigned i = 0; i != MaskNumElts; ++i) {
5556     // Note that recursion is limited for each vector element, so if any element
5557     // exceeds the limit, this will fail to simplify.
5558     RootVec =
5559         foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse);
5560 
5561     // We can't replace a widening/narrowing shuffle with one of its operands.
5562     if (!RootVec || RootVec->getType() != RetTy)
5563       return nullptr;
5564   }
5565   return RootVec;
5566 }
5567 
5568 /// Given operands for a ShuffleVectorInst, fold the result or return null.
simplifyShuffleVectorInst(Value * Op0,Value * Op1,ArrayRef<int> Mask,Type * RetTy,const SimplifyQuery & Q)5569 Value *llvm::simplifyShuffleVectorInst(Value *Op0, Value *Op1,
5570                                        ArrayRef<int> Mask, Type *RetTy,
5571                                        const SimplifyQuery &Q) {
5572   return ::simplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit);
5573 }
5574 
foldConstant(Instruction::UnaryOps Opcode,Value * & Op,const SimplifyQuery & Q)5575 static Constant *foldConstant(Instruction::UnaryOps Opcode, Value *&Op,
5576                               const SimplifyQuery &Q) {
5577   if (auto *C = dyn_cast<Constant>(Op))
5578     return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL);
5579   return nullptr;
5580 }
5581 
5582 /// Given the operand for an FNeg, see if we can fold the result.  If not, this
5583 /// returns null.
simplifyFNegInst(Value * Op,FastMathFlags FMF,const SimplifyQuery & Q,unsigned MaxRecurse)5584 static Value *simplifyFNegInst(Value *Op, FastMathFlags FMF,
5585                                const SimplifyQuery &Q, unsigned MaxRecurse) {
5586   if (Constant *C = foldConstant(Instruction::FNeg, Op, Q))
5587     return C;
5588 
5589   Value *X;
5590   // fneg (fneg X) ==> X
5591   if (match(Op, m_FNeg(m_Value(X))))
5592     return X;
5593 
5594   return nullptr;
5595 }
5596 
simplifyFNegInst(Value * Op,FastMathFlags FMF,const SimplifyQuery & Q)5597 Value *llvm::simplifyFNegInst(Value *Op, FastMathFlags FMF,
5598                               const SimplifyQuery &Q) {
5599   return ::simplifyFNegInst(Op, FMF, Q, RecursionLimit);
5600 }
5601 
5602 /// Try to propagate existing NaN values when possible. If not, replace the
5603 /// constant or elements in the constant with a canonical NaN.
propagateNaN(Constant * In)5604 static Constant *propagateNaN(Constant *In) {
5605   Type *Ty = In->getType();
5606   if (auto *VecTy = dyn_cast<FixedVectorType>(Ty)) {
5607     unsigned NumElts = VecTy->getNumElements();
5608     SmallVector<Constant *, 32> NewC(NumElts);
5609     for (unsigned i = 0; i != NumElts; ++i) {
5610       Constant *EltC = In->getAggregateElement(i);
5611       // Poison elements propagate. NaN propagates except signaling is quieted.
5612       // Replace unknown or undef elements with canonical NaN.
5613       if (EltC && isa<PoisonValue>(EltC))
5614         NewC[i] = EltC;
5615       else if (EltC && EltC->isNaN())
5616         NewC[i] = ConstantFP::get(
5617             EltC->getType(), cast<ConstantFP>(EltC)->getValue().makeQuiet());
5618       else
5619         NewC[i] = ConstantFP::getNaN(VecTy->getElementType());
5620     }
5621     return ConstantVector::get(NewC);
5622   }
5623 
5624   // If it is not a fixed vector, but not a simple NaN either, return a
5625   // canonical NaN.
5626   if (!In->isNaN())
5627     return ConstantFP::getNaN(Ty);
5628 
5629   // If we known this is a NaN, and it's scalable vector, we must have a splat
5630   // on our hands. Grab that before splatting a QNaN constant.
5631   if (isa<ScalableVectorType>(Ty)) {
5632     auto *Splat = In->getSplatValue();
5633     assert(Splat && Splat->isNaN() &&
5634            "Found a scalable-vector NaN but not a splat");
5635     In = Splat;
5636   }
5637 
5638   // Propagate an existing QNaN constant. If it is an SNaN, make it quiet, but
5639   // preserve the sign/payload.
5640   return ConstantFP::get(Ty, cast<ConstantFP>(In)->getValue().makeQuiet());
5641 }
5642 
5643 /// Perform folds that are common to any floating-point operation. This implies
5644 /// transforms based on poison/undef/NaN because the operation itself makes no
5645 /// difference to the result.
simplifyFPOp(ArrayRef<Value * > Ops,FastMathFlags FMF,const SimplifyQuery & Q,fp::ExceptionBehavior ExBehavior,RoundingMode Rounding)5646 static Constant *simplifyFPOp(ArrayRef<Value *> Ops, FastMathFlags FMF,
5647                               const SimplifyQuery &Q,
5648                               fp::ExceptionBehavior ExBehavior,
5649                               RoundingMode Rounding) {
5650   // Poison is independent of anything else. It always propagates from an
5651   // operand to a math result.
5652   if (any_of(Ops, [](Value *V) { return match(V, m_Poison()); }))
5653     return PoisonValue::get(Ops[0]->getType());
5654 
5655   for (Value *V : Ops) {
5656     bool IsNan = match(V, m_NaN());
5657     bool IsInf = match(V, m_Inf());
5658     bool IsUndef = Q.isUndefValue(V);
5659 
5660     // If this operation has 'nnan' or 'ninf' and at least 1 disallowed operand
5661     // (an undef operand can be chosen to be Nan/Inf), then the result of
5662     // this operation is poison.
5663     if (FMF.noNaNs() && (IsNan || IsUndef))
5664       return PoisonValue::get(V->getType());
5665     if (FMF.noInfs() && (IsInf || IsUndef))
5666       return PoisonValue::get(V->getType());
5667 
5668     if (isDefaultFPEnvironment(ExBehavior, Rounding)) {
5669       // Undef does not propagate because undef means that all bits can take on
5670       // any value. If this is undef * NaN for example, then the result values
5671       // (at least the exponent bits) are limited. Assume the undef is a
5672       // canonical NaN and propagate that.
5673       if (IsUndef)
5674         return ConstantFP::getNaN(V->getType());
5675       if (IsNan)
5676         return propagateNaN(cast<Constant>(V));
5677     } else if (ExBehavior != fp::ebStrict) {
5678       if (IsNan)
5679         return propagateNaN(cast<Constant>(V));
5680     }
5681   }
5682   return nullptr;
5683 }
5684 
5685 /// Given operands for an FAdd, see if we can fold the result.  If not, this
5686 /// returns null.
5687 static Value *
simplifyFAddInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,unsigned MaxRecurse,fp::ExceptionBehavior ExBehavior=fp::ebIgnore,RoundingMode Rounding=RoundingMode::NearestTiesToEven)5688 simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5689                  const SimplifyQuery &Q, unsigned MaxRecurse,
5690                  fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
5691                  RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
5692   if (isDefaultFPEnvironment(ExBehavior, Rounding))
5693     if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q))
5694       return C;
5695 
5696   if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
5697     return C;
5698 
5699   // fadd X, -0 ==> X
5700   // With strict/constrained FP, we have these possible edge cases that do
5701   // not simplify to Op0:
5702   // fadd SNaN, -0.0 --> QNaN
5703   // fadd +0.0, -0.0 --> -0.0 (but only with round toward negative)
5704   if (canIgnoreSNaN(ExBehavior, FMF) &&
5705       (!canRoundingModeBe(Rounding, RoundingMode::TowardNegative) ||
5706        FMF.noSignedZeros()))
5707     if (match(Op1, m_NegZeroFP()))
5708       return Op0;
5709 
5710   // fadd X, 0 ==> X, when we know X is not -0
5711   if (canIgnoreSNaN(ExBehavior, FMF))
5712     if (match(Op1, m_PosZeroFP()) &&
5713         (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, Q)))
5714       return Op0;
5715 
5716   if (!isDefaultFPEnvironment(ExBehavior, Rounding))
5717     return nullptr;
5718 
5719   if (FMF.noNaNs()) {
5720     // With nnan: X + {+/-}Inf --> {+/-}Inf
5721     if (match(Op1, m_Inf()))
5722       return Op1;
5723 
5724     // With nnan: -X + X --> 0.0 (and commuted variant)
5725     // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN.
5726     // Negative zeros are allowed because we always end up with positive zero:
5727     // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0
5728     // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0
5729     // X =  0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0
5730     // X =  0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0
5731     if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) ||
5732         match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0))))
5733       return ConstantFP::getZero(Op0->getType());
5734 
5735     if (match(Op0, m_FNeg(m_Specific(Op1))) ||
5736         match(Op1, m_FNeg(m_Specific(Op0))))
5737       return ConstantFP::getZero(Op0->getType());
5738   }
5739 
5740   // (X - Y) + Y --> X
5741   // Y + (X - Y) --> X
5742   Value *X;
5743   if (FMF.noSignedZeros() && FMF.allowReassoc() &&
5744       (match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) ||
5745        match(Op1, m_FSub(m_Value(X), m_Specific(Op0)))))
5746     return X;
5747 
5748   return nullptr;
5749 }
5750 
5751 /// Given operands for an FSub, see if we can fold the result.  If not, this
5752 /// returns null.
5753 static Value *
simplifyFSubInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,unsigned MaxRecurse,fp::ExceptionBehavior ExBehavior=fp::ebIgnore,RoundingMode Rounding=RoundingMode::NearestTiesToEven)5754 simplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5755                  const SimplifyQuery &Q, unsigned MaxRecurse,
5756                  fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
5757                  RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
5758   if (isDefaultFPEnvironment(ExBehavior, Rounding))
5759     if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q))
5760       return C;
5761 
5762   if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
5763     return C;
5764 
5765   // fsub X, +0 ==> X
5766   if (canIgnoreSNaN(ExBehavior, FMF) &&
5767       (!canRoundingModeBe(Rounding, RoundingMode::TowardNegative) ||
5768        FMF.noSignedZeros()))
5769     if (match(Op1, m_PosZeroFP()))
5770       return Op0;
5771 
5772   // fsub X, -0 ==> X, when we know X is not -0
5773   if (canIgnoreSNaN(ExBehavior, FMF))
5774     if (match(Op1, m_NegZeroFP()) &&
5775         (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, Q)))
5776       return Op0;
5777 
5778   // fsub -0.0, (fsub -0.0, X) ==> X
5779   // fsub -0.0, (fneg X) ==> X
5780   Value *X;
5781   if (canIgnoreSNaN(ExBehavior, FMF))
5782     if (match(Op0, m_NegZeroFP()) && match(Op1, m_FNeg(m_Value(X))))
5783       return X;
5784 
5785   // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.
5786   // fsub 0.0, (fneg X) ==> X if signed zeros are ignored.
5787   if (canIgnoreSNaN(ExBehavior, FMF))
5788     if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) &&
5789         (match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) ||
5790          match(Op1, m_FNeg(m_Value(X)))))
5791       return X;
5792 
5793   if (!isDefaultFPEnvironment(ExBehavior, Rounding))
5794     return nullptr;
5795 
5796   if (FMF.noNaNs()) {
5797     // fsub nnan x, x ==> 0.0
5798     if (Op0 == Op1)
5799       return Constant::getNullValue(Op0->getType());
5800 
5801     // With nnan: {+/-}Inf - X --> {+/-}Inf
5802     if (match(Op0, m_Inf()))
5803       return Op0;
5804 
5805     // With nnan: X - {+/-}Inf --> {-/+}Inf
5806     if (match(Op1, m_Inf()))
5807       return foldConstant(Instruction::FNeg, Op1, Q);
5808   }
5809 
5810   // Y - (Y - X) --> X
5811   // (X + Y) - Y --> X
5812   if (FMF.noSignedZeros() && FMF.allowReassoc() &&
5813       (match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) ||
5814        match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X)))))
5815     return X;
5816 
5817   return nullptr;
5818 }
5819 
simplifyFMAFMul(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,unsigned MaxRecurse,fp::ExceptionBehavior ExBehavior,RoundingMode Rounding)5820 static Value *simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF,
5821                               const SimplifyQuery &Q, unsigned MaxRecurse,
5822                               fp::ExceptionBehavior ExBehavior,
5823                               RoundingMode Rounding) {
5824   if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
5825     return C;
5826 
5827   if (!isDefaultFPEnvironment(ExBehavior, Rounding))
5828     return nullptr;
5829 
5830   // Canonicalize special constants as operand 1.
5831   if (match(Op0, m_FPOne()) || match(Op0, m_AnyZeroFP()))
5832     std::swap(Op0, Op1);
5833 
5834   // X * 1.0 --> X
5835   if (match(Op1, m_FPOne()))
5836     return Op0;
5837 
5838   if (match(Op1, m_AnyZeroFP())) {
5839     // X * 0.0 --> 0.0 (with nnan and nsz)
5840     if (FMF.noNaNs() && FMF.noSignedZeros())
5841       return ConstantFP::getZero(Op0->getType());
5842 
5843     KnownFPClass Known = computeKnownFPClass(Op0, FMF, fcInf | fcNan, Q);
5844     if (Known.isKnownNever(fcInf | fcNan)) {
5845       // if nsz is set, return 0.0
5846       if (FMF.noSignedZeros())
5847         return ConstantFP::getZero(Op0->getType());
5848       // +normal number * (-)0.0 --> (-)0.0
5849       if (Known.SignBit == false)
5850         return Op1;
5851       // -normal number * (-)0.0 --> -(-)0.0
5852       if (Known.SignBit == true)
5853         return foldConstant(Instruction::FNeg, Op1, Q);
5854     }
5855   }
5856 
5857   // sqrt(X) * sqrt(X) --> X, if we can:
5858   // 1. Remove the intermediate rounding (reassociate).
5859   // 2. Ignore non-zero negative numbers because sqrt would produce NAN.
5860   // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0.
5861   Value *X;
5862   if (Op0 == Op1 && match(Op0, m_Sqrt(m_Value(X))) && FMF.allowReassoc() &&
5863       FMF.noNaNs() && FMF.noSignedZeros())
5864     return X;
5865 
5866   return nullptr;
5867 }
5868 
5869 /// Given the operands for an FMul, see if we can fold the result
5870 static Value *
simplifyFMulInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,unsigned MaxRecurse,fp::ExceptionBehavior ExBehavior=fp::ebIgnore,RoundingMode Rounding=RoundingMode::NearestTiesToEven)5871 simplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5872                  const SimplifyQuery &Q, unsigned MaxRecurse,
5873                  fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
5874                  RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
5875   if (isDefaultFPEnvironment(ExBehavior, Rounding))
5876     if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q))
5877       return C;
5878 
5879   // Now apply simplifications that do not require rounding.
5880   return simplifyFMAFMul(Op0, Op1, FMF, Q, MaxRecurse, ExBehavior, Rounding);
5881 }
5882 
simplifyFAddInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,fp::ExceptionBehavior ExBehavior,RoundingMode Rounding)5883 Value *llvm::simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5884                               const SimplifyQuery &Q,
5885                               fp::ExceptionBehavior ExBehavior,
5886                               RoundingMode Rounding) {
5887   return ::simplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
5888                             Rounding);
5889 }
5890 
simplifyFSubInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,fp::ExceptionBehavior ExBehavior,RoundingMode Rounding)5891 Value *llvm::simplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5892                               const SimplifyQuery &Q,
5893                               fp::ExceptionBehavior ExBehavior,
5894                               RoundingMode Rounding) {
5895   return ::simplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
5896                             Rounding);
5897 }
5898 
simplifyFMulInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,fp::ExceptionBehavior ExBehavior,RoundingMode Rounding)5899 Value *llvm::simplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5900                               const SimplifyQuery &Q,
5901                               fp::ExceptionBehavior ExBehavior,
5902                               RoundingMode Rounding) {
5903   return ::simplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
5904                             Rounding);
5905 }
5906 
simplifyFMAFMul(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,fp::ExceptionBehavior ExBehavior,RoundingMode Rounding)5907 Value *llvm::simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF,
5908                              const SimplifyQuery &Q,
5909                              fp::ExceptionBehavior ExBehavior,
5910                              RoundingMode Rounding) {
5911   return ::simplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
5912                            Rounding);
5913 }
5914 
5915 static Value *
simplifyFDivInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,unsigned,fp::ExceptionBehavior ExBehavior=fp::ebIgnore,RoundingMode Rounding=RoundingMode::NearestTiesToEven)5916 simplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5917                  const SimplifyQuery &Q, unsigned,
5918                  fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
5919                  RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
5920   if (isDefaultFPEnvironment(ExBehavior, Rounding))
5921     if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q))
5922       return C;
5923 
5924   if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
5925     return C;
5926 
5927   if (!isDefaultFPEnvironment(ExBehavior, Rounding))
5928     return nullptr;
5929 
5930   // X / 1.0 -> X
5931   if (match(Op1, m_FPOne()))
5932     return Op0;
5933 
5934   // 0 / X -> 0
5935   // Requires that NaNs are off (X could be zero) and signed zeroes are
5936   // ignored (X could be positive or negative, so the output sign is unknown).
5937   if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()))
5938     return ConstantFP::getZero(Op0->getType());
5939 
5940   if (FMF.noNaNs()) {
5941     // X / X -> 1.0 is legal when NaNs are ignored.
5942     // We can ignore infinities because INF/INF is NaN.
5943     if (Op0 == Op1)
5944       return ConstantFP::get(Op0->getType(), 1.0);
5945 
5946     // (X * Y) / Y --> X if we can reassociate to the above form.
5947     Value *X;
5948     if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1))))
5949       return X;
5950 
5951     // -X /  X -> -1.0 and
5952     //  X / -X -> -1.0 are legal when NaNs are ignored.
5953     // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored.
5954     if (match(Op0, m_FNegNSZ(m_Specific(Op1))) ||
5955         match(Op1, m_FNegNSZ(m_Specific(Op0))))
5956       return ConstantFP::get(Op0->getType(), -1.0);
5957 
5958     // nnan ninf X / [-]0.0 -> poison
5959     if (FMF.noInfs() && match(Op1, m_AnyZeroFP()))
5960       return PoisonValue::get(Op1->getType());
5961   }
5962 
5963   return nullptr;
5964 }
5965 
simplifyFDivInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,fp::ExceptionBehavior ExBehavior,RoundingMode Rounding)5966 Value *llvm::simplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5967                               const SimplifyQuery &Q,
5968                               fp::ExceptionBehavior ExBehavior,
5969                               RoundingMode Rounding) {
5970   return ::simplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
5971                             Rounding);
5972 }
5973 
5974 static Value *
simplifyFRemInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,unsigned,fp::ExceptionBehavior ExBehavior=fp::ebIgnore,RoundingMode Rounding=RoundingMode::NearestTiesToEven)5975 simplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
5976                  const SimplifyQuery &Q, unsigned,
5977                  fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
5978                  RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
5979   if (isDefaultFPEnvironment(ExBehavior, Rounding))
5980     if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q))
5981       return C;
5982 
5983   if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
5984     return C;
5985 
5986   if (!isDefaultFPEnvironment(ExBehavior, Rounding))
5987     return nullptr;
5988 
5989   // Unlike fdiv, the result of frem always matches the sign of the dividend.
5990   // The constant match may include undef elements in a vector, so return a full
5991   // zero constant as the result.
5992   if (FMF.noNaNs()) {
5993     // +0 % X -> 0
5994     if (match(Op0, m_PosZeroFP()))
5995       return ConstantFP::getZero(Op0->getType());
5996     // -0 % X -> -0
5997     if (match(Op0, m_NegZeroFP()))
5998       return ConstantFP::getNegativeZero(Op0->getType());
5999   }
6000 
6001   return nullptr;
6002 }
6003 
simplifyFRemInst(Value * Op0,Value * Op1,FastMathFlags FMF,const SimplifyQuery & Q,fp::ExceptionBehavior ExBehavior,RoundingMode Rounding)6004 Value *llvm::simplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
6005                               const SimplifyQuery &Q,
6006                               fp::ExceptionBehavior ExBehavior,
6007                               RoundingMode Rounding) {
6008   return ::simplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
6009                             Rounding);
6010 }
6011 
6012 //=== Helper functions for higher up the class hierarchy.
6013 
6014 /// Given the operand for a UnaryOperator, see if we can fold the result.
6015 /// If not, this returns null.
simplifyUnOp(unsigned Opcode,Value * Op,const SimplifyQuery & Q,unsigned MaxRecurse)6016 static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q,
6017                            unsigned MaxRecurse) {
6018   switch (Opcode) {
6019   case Instruction::FNeg:
6020     return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse);
6021   default:
6022     llvm_unreachable("Unexpected opcode");
6023   }
6024 }
6025 
6026 /// Given the operand for a UnaryOperator, see if we can fold the result.
6027 /// If not, this returns null.
6028 /// Try to use FastMathFlags when folding the result.
simplifyFPUnOp(unsigned Opcode,Value * Op,const FastMathFlags & FMF,const SimplifyQuery & Q,unsigned MaxRecurse)6029 static Value *simplifyFPUnOp(unsigned Opcode, Value *Op,
6030                              const FastMathFlags &FMF, const SimplifyQuery &Q,
6031                              unsigned MaxRecurse) {
6032   switch (Opcode) {
6033   case Instruction::FNeg:
6034     return simplifyFNegInst(Op, FMF, Q, MaxRecurse);
6035   default:
6036     return simplifyUnOp(Opcode, Op, Q, MaxRecurse);
6037   }
6038 }
6039 
simplifyUnOp(unsigned Opcode,Value * Op,const SimplifyQuery & Q)6040 Value *llvm::simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) {
6041   return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit);
6042 }
6043 
simplifyUnOp(unsigned Opcode,Value * Op,FastMathFlags FMF,const SimplifyQuery & Q)6044 Value *llvm::simplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF,
6045                           const SimplifyQuery &Q) {
6046   return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit);
6047 }
6048 
6049 /// Given operands for a BinaryOperator, see if we can fold the result.
6050 /// If not, this returns null.
simplifyBinOp(unsigned Opcode,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)6051 static Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
6052                             const SimplifyQuery &Q, unsigned MaxRecurse) {
6053   switch (Opcode) {
6054   case Instruction::Add:
6055     return simplifyAddInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q,
6056                            MaxRecurse);
6057   case Instruction::Sub:
6058     return simplifySubInst(LHS, RHS,  /* IsNSW */ false, /* IsNUW */ false, Q,
6059                            MaxRecurse);
6060   case Instruction::Mul:
6061     return simplifyMulInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q,
6062                            MaxRecurse);
6063   case Instruction::SDiv:
6064     return simplifySDivInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse);
6065   case Instruction::UDiv:
6066     return simplifyUDivInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse);
6067   case Instruction::SRem:
6068     return simplifySRemInst(LHS, RHS, Q, MaxRecurse);
6069   case Instruction::URem:
6070     return simplifyURemInst(LHS, RHS, Q, MaxRecurse);
6071   case Instruction::Shl:
6072     return simplifyShlInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q,
6073                            MaxRecurse);
6074   case Instruction::LShr:
6075     return simplifyLShrInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse);
6076   case Instruction::AShr:
6077     return simplifyAShrInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse);
6078   case Instruction::And:
6079     return simplifyAndInst(LHS, RHS, Q, MaxRecurse);
6080   case Instruction::Or:
6081     return simplifyOrInst(LHS, RHS, Q, MaxRecurse);
6082   case Instruction::Xor:
6083     return simplifyXorInst(LHS, RHS, Q, MaxRecurse);
6084   case Instruction::FAdd:
6085     return simplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
6086   case Instruction::FSub:
6087     return simplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
6088   case Instruction::FMul:
6089     return simplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
6090   case Instruction::FDiv:
6091     return simplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
6092   case Instruction::FRem:
6093     return simplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
6094   default:
6095     llvm_unreachable("Unexpected opcode");
6096   }
6097 }
6098 
6099 /// Given operands for a BinaryOperator, see if we can fold the result.
6100 /// If not, this returns null.
6101 /// Try to use FastMathFlags when folding the result.
simplifyBinOp(unsigned Opcode,Value * LHS,Value * RHS,const FastMathFlags & FMF,const SimplifyQuery & Q,unsigned MaxRecurse)6102 static Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
6103                             const FastMathFlags &FMF, const SimplifyQuery &Q,
6104                             unsigned MaxRecurse) {
6105   switch (Opcode) {
6106   case Instruction::FAdd:
6107     return simplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse);
6108   case Instruction::FSub:
6109     return simplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse);
6110   case Instruction::FMul:
6111     return simplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse);
6112   case Instruction::FDiv:
6113     return simplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse);
6114   default:
6115     return simplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
6116   }
6117 }
6118 
simplifyBinOp(unsigned Opcode,Value * LHS,Value * RHS,const SimplifyQuery & Q)6119 Value *llvm::simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
6120                            const SimplifyQuery &Q) {
6121   return ::simplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit);
6122 }
6123 
simplifyBinOp(unsigned Opcode,Value * LHS,Value * RHS,FastMathFlags FMF,const SimplifyQuery & Q)6124 Value *llvm::simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
6125                            FastMathFlags FMF, const SimplifyQuery &Q) {
6126   return ::simplifyBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit);
6127 }
6128 
6129 /// Given operands for a CmpInst, see if we can fold the result.
simplifyCmpInst(CmpPredicate Predicate,Value * LHS,Value * RHS,const SimplifyQuery & Q,unsigned MaxRecurse)6130 static Value *simplifyCmpInst(CmpPredicate Predicate, Value *LHS, Value *RHS,
6131                               const SimplifyQuery &Q, unsigned MaxRecurse) {
6132   if (CmpInst::isIntPredicate(Predicate))
6133     return simplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
6134   return simplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse);
6135 }
6136 
simplifyCmpInst(CmpPredicate Predicate,Value * LHS,Value * RHS,const SimplifyQuery & Q)6137 Value *llvm::simplifyCmpInst(CmpPredicate Predicate, Value *LHS, Value *RHS,
6138                              const SimplifyQuery &Q) {
6139   return ::simplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit);
6140 }
6141 
isIdempotent(Intrinsic::ID ID)6142 static bool isIdempotent(Intrinsic::ID ID) {
6143   switch (ID) {
6144   default:
6145     return false;
6146 
6147   // Unary idempotent: f(f(x)) = f(x)
6148   case Intrinsic::fabs:
6149   case Intrinsic::floor:
6150   case Intrinsic::ceil:
6151   case Intrinsic::trunc:
6152   case Intrinsic::rint:
6153   case Intrinsic::nearbyint:
6154   case Intrinsic::round:
6155   case Intrinsic::roundeven:
6156   case Intrinsic::canonicalize:
6157   case Intrinsic::arithmetic_fence:
6158     return true;
6159   }
6160 }
6161 
6162 /// Return true if the intrinsic rounds a floating-point value to an integral
6163 /// floating-point value (not an integer type).
removesFPFraction(Intrinsic::ID ID)6164 static bool removesFPFraction(Intrinsic::ID ID) {
6165   switch (ID) {
6166   default:
6167     return false;
6168 
6169   case Intrinsic::floor:
6170   case Intrinsic::ceil:
6171   case Intrinsic::trunc:
6172   case Intrinsic::rint:
6173   case Intrinsic::nearbyint:
6174   case Intrinsic::round:
6175   case Intrinsic::roundeven:
6176     return true;
6177   }
6178 }
6179 
simplifyRelativeLoad(Constant * Ptr,Constant * Offset,const DataLayout & DL)6180 static Value *simplifyRelativeLoad(Constant *Ptr, Constant *Offset,
6181                                    const DataLayout &DL) {
6182   GlobalValue *PtrSym;
6183   APInt PtrOffset;
6184   if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL))
6185     return nullptr;
6186 
6187   Type *Int32Ty = Type::getInt32Ty(Ptr->getContext());
6188 
6189   auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset);
6190   if (!OffsetConstInt || OffsetConstInt->getBitWidth() > 64)
6191     return nullptr;
6192 
6193   APInt OffsetInt = OffsetConstInt->getValue().sextOrTrunc(
6194       DL.getIndexTypeSizeInBits(Ptr->getType()));
6195   if (OffsetInt.srem(4) != 0)
6196     return nullptr;
6197 
6198   Constant *Loaded =
6199       ConstantFoldLoadFromConstPtr(Ptr, Int32Ty, std::move(OffsetInt), DL);
6200   if (!Loaded)
6201     return nullptr;
6202 
6203   auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded);
6204   if (!LoadedCE)
6205     return nullptr;
6206 
6207   if (LoadedCE->getOpcode() == Instruction::Trunc) {
6208     LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
6209     if (!LoadedCE)
6210       return nullptr;
6211   }
6212 
6213   if (LoadedCE->getOpcode() != Instruction::Sub)
6214     return nullptr;
6215 
6216   auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
6217   if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt)
6218     return nullptr;
6219   auto *LoadedLHSPtr = LoadedLHS->getOperand(0);
6220 
6221   Constant *LoadedRHS = LoadedCE->getOperand(1);
6222   GlobalValue *LoadedRHSSym;
6223   APInt LoadedRHSOffset;
6224   if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset,
6225                                   DL) ||
6226       PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset)
6227     return nullptr;
6228 
6229   return LoadedLHSPtr;
6230 }
6231 
6232 // TODO: Need to pass in FastMathFlags
simplifyLdexp(Value * Op0,Value * Op1,const SimplifyQuery & Q,bool IsStrict)6233 static Value *simplifyLdexp(Value *Op0, Value *Op1, const SimplifyQuery &Q,
6234                             bool IsStrict) {
6235   // ldexp(poison, x) -> poison
6236   // ldexp(x, poison) -> poison
6237   if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1))
6238     return Op0;
6239 
6240   // ldexp(undef, x) -> nan
6241   if (Q.isUndefValue(Op0))
6242     return ConstantFP::getNaN(Op0->getType());
6243 
6244   if (!IsStrict) {
6245     // TODO: Could insert a canonicalize for strict
6246 
6247     // ldexp(x, undef) -> x
6248     if (Q.isUndefValue(Op1))
6249       return Op0;
6250   }
6251 
6252   const APFloat *C = nullptr;
6253   match(Op0, PatternMatch::m_APFloat(C));
6254 
6255   // These cases should be safe, even with strictfp.
6256   // ldexp(0.0, x) -> 0.0
6257   // ldexp(-0.0, x) -> -0.0
6258   // ldexp(inf, x) -> inf
6259   // ldexp(-inf, x) -> -inf
6260   if (C && (C->isZero() || C->isInfinity()))
6261     return Op0;
6262 
6263   // These are canonicalization dropping, could do it if we knew how we could
6264   // ignore denormal flushes and target handling of nan payload bits.
6265   if (IsStrict)
6266     return nullptr;
6267 
6268   // TODO: Could quiet this with strictfp if the exception mode isn't strict.
6269   if (C && C->isNaN())
6270     return ConstantFP::get(Op0->getType(), C->makeQuiet());
6271 
6272   // ldexp(x, 0) -> x
6273 
6274   // TODO: Could fold this if we know the exception mode isn't
6275   // strict, we know the denormal mode and other target modes.
6276   if (match(Op1, PatternMatch::m_ZeroInt()))
6277     return Op0;
6278 
6279   return nullptr;
6280 }
6281 
simplifyUnaryIntrinsic(Function * F,Value * Op0,const SimplifyQuery & Q,const CallBase * Call)6282 static Value *simplifyUnaryIntrinsic(Function *F, Value *Op0,
6283                                      const SimplifyQuery &Q,
6284                                      const CallBase *Call) {
6285   // Idempotent functions return the same result when called repeatedly.
6286   Intrinsic::ID IID = F->getIntrinsicID();
6287   if (isIdempotent(IID))
6288     if (auto *II = dyn_cast<IntrinsicInst>(Op0))
6289       if (II->getIntrinsicID() == IID)
6290         return II;
6291 
6292   if (removesFPFraction(IID)) {
6293     // Converting from int or calling a rounding function always results in a
6294     // finite integral number or infinity. For those inputs, rounding functions
6295     // always return the same value, so the (2nd) rounding is eliminated. Ex:
6296     // floor (sitofp x) -> sitofp x
6297     // round (ceil x) -> ceil x
6298     auto *II = dyn_cast<IntrinsicInst>(Op0);
6299     if ((II && removesFPFraction(II->getIntrinsicID())) ||
6300         match(Op0, m_SIToFP(m_Value())) || match(Op0, m_UIToFP(m_Value())))
6301       return Op0;
6302   }
6303 
6304   Value *X;
6305   switch (IID) {
6306   case Intrinsic::fabs:
6307     if (computeKnownFPSignBit(Op0, Q) == false)
6308       return Op0;
6309     break;
6310   case Intrinsic::bswap:
6311     // bswap(bswap(x)) -> x
6312     if (match(Op0, m_BSwap(m_Value(X))))
6313       return X;
6314     break;
6315   case Intrinsic::bitreverse:
6316     // bitreverse(bitreverse(x)) -> x
6317     if (match(Op0, m_BitReverse(m_Value(X))))
6318       return X;
6319     break;
6320   case Intrinsic::ctpop: {
6321     // ctpop(X) -> 1 iff X is non-zero power of 2.
6322     if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ false, Q.AC, Q.CxtI, Q.DT))
6323       return ConstantInt::get(Op0->getType(), 1);
6324     // If everything but the lowest bit is zero, that bit is the pop-count. Ex:
6325     // ctpop(and X, 1) --> and X, 1
6326     unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
6327     if (MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, BitWidth - 1),
6328                           Q))
6329       return Op0;
6330     break;
6331   }
6332   case Intrinsic::exp:
6333     // exp(log(x)) -> x
6334     if (Call->hasAllowReassoc() &&
6335         match(Op0, m_Intrinsic<Intrinsic::log>(m_Value(X))))
6336       return X;
6337     break;
6338   case Intrinsic::exp2:
6339     // exp2(log2(x)) -> x
6340     if (Call->hasAllowReassoc() &&
6341         match(Op0, m_Intrinsic<Intrinsic::log2>(m_Value(X))))
6342       return X;
6343     break;
6344   case Intrinsic::exp10:
6345     // exp10(log10(x)) -> x
6346     if (Call->hasAllowReassoc() &&
6347         match(Op0, m_Intrinsic<Intrinsic::log10>(m_Value(X))))
6348       return X;
6349     break;
6350   case Intrinsic::log:
6351     // log(exp(x)) -> x
6352     if (Call->hasAllowReassoc() &&
6353         match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X))))
6354       return X;
6355     break;
6356   case Intrinsic::log2:
6357     // log2(exp2(x)) -> x
6358     if (Call->hasAllowReassoc() &&
6359         (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) ||
6360          match(Op0,
6361                m_Intrinsic<Intrinsic::pow>(m_SpecificFP(2.0), m_Value(X)))))
6362       return X;
6363     break;
6364   case Intrinsic::log10:
6365     // log10(pow(10.0, x)) -> x
6366     // log10(exp10(x)) -> x
6367     if (Call->hasAllowReassoc() &&
6368         (match(Op0, m_Intrinsic<Intrinsic::exp10>(m_Value(X))) ||
6369          match(Op0,
6370                m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0), m_Value(X)))))
6371       return X;
6372     break;
6373   case Intrinsic::vector_reverse:
6374     // vector.reverse(vector.reverse(x)) -> x
6375     if (match(Op0, m_VecReverse(m_Value(X))))
6376       return X;
6377     // vector.reverse(splat(X)) -> splat(X)
6378     if (isSplatValue(Op0))
6379       return Op0;
6380     break;
6381   default:
6382     break;
6383   }
6384 
6385   return nullptr;
6386 }
6387 
6388 /// Given a min/max intrinsic, see if it can be removed based on having an
6389 /// operand that is another min/max intrinsic with shared operand(s). The caller
6390 /// is expected to swap the operand arguments to handle commutation.
foldMinMaxSharedOp(Intrinsic::ID IID,Value * Op0,Value * Op1)6391 static Value *foldMinMaxSharedOp(Intrinsic::ID IID, Value *Op0, Value *Op1) {
6392   Value *X, *Y;
6393   if (!match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y))))
6394     return nullptr;
6395 
6396   auto *MM0 = dyn_cast<IntrinsicInst>(Op0);
6397   if (!MM0)
6398     return nullptr;
6399   Intrinsic::ID IID0 = MM0->getIntrinsicID();
6400 
6401   if (Op1 == X || Op1 == Y ||
6402       match(Op1, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) {
6403     // max (max X, Y), X --> max X, Y
6404     if (IID0 == IID)
6405       return MM0;
6406     // max (min X, Y), X --> X
6407     if (IID0 == getInverseMinMaxIntrinsic(IID))
6408       return Op1;
6409   }
6410   return nullptr;
6411 }
6412 
6413 /// Given a min/max intrinsic, see if it can be removed based on having an
6414 /// operand that is another min/max intrinsic with shared operand(s). The caller
6415 /// is expected to swap the operand arguments to handle commutation.
foldMinimumMaximumSharedOp(Intrinsic::ID IID,Value * Op0,Value * Op1)6416 static Value *foldMinimumMaximumSharedOp(Intrinsic::ID IID, Value *Op0,
6417                                          Value *Op1) {
6418   assert((IID == Intrinsic::maxnum || IID == Intrinsic::minnum ||
6419           IID == Intrinsic::maximum || IID == Intrinsic::minimum) &&
6420          "Unsupported intrinsic");
6421 
6422   auto *M0 = dyn_cast<IntrinsicInst>(Op0);
6423   // If Op0 is not the same intrinsic as IID, do not process.
6424   // This is a difference with integer min/max handling. We do not process the
6425   // case like max(min(X,Y),min(X,Y)) => min(X,Y). But it can be handled by GVN.
6426   if (!M0 || M0->getIntrinsicID() != IID)
6427     return nullptr;
6428   Value *X0 = M0->getOperand(0);
6429   Value *Y0 = M0->getOperand(1);
6430   // Simple case, m(m(X,Y), X) => m(X, Y)
6431   //              m(m(X,Y), Y) => m(X, Y)
6432   // For minimum/maximum, X is NaN => m(NaN, Y) == NaN and m(NaN, NaN) == NaN.
6433   // For minimum/maximum, Y is NaN => m(X, NaN) == NaN  and m(NaN, NaN) == NaN.
6434   // For minnum/maxnum, X is NaN => m(NaN, Y) == Y and m(Y, Y) == Y.
6435   // For minnum/maxnum, Y is NaN => m(X, NaN) == X and m(X, NaN) == X.
6436   if (X0 == Op1 || Y0 == Op1)
6437     return M0;
6438 
6439   auto *M1 = dyn_cast<IntrinsicInst>(Op1);
6440   if (!M1)
6441     return nullptr;
6442   Value *X1 = M1->getOperand(0);
6443   Value *Y1 = M1->getOperand(1);
6444   Intrinsic::ID IID1 = M1->getIntrinsicID();
6445   // we have a case m(m(X,Y),m'(X,Y)) taking into account m' is commutative.
6446   // if m' is m or inversion of m => m(m(X,Y),m'(X,Y)) == m(X,Y).
6447   // For minimum/maximum, X is NaN => m(NaN,Y) == m'(NaN, Y) == NaN.
6448   // For minimum/maximum, Y is NaN => m(X,NaN) == m'(X, NaN) == NaN.
6449   // For minnum/maxnum, X is NaN => m(NaN,Y) == m'(NaN, Y) == Y.
6450   // For minnum/maxnum, Y is NaN => m(X,NaN) == m'(X, NaN) == X.
6451   if ((X0 == X1 && Y0 == Y1) || (X0 == Y1 && Y0 == X1))
6452     if (IID1 == IID || getInverseMinMaxIntrinsic(IID1) == IID)
6453       return M0;
6454 
6455   return nullptr;
6456 }
6457 
simplifyBinaryIntrinsic(Intrinsic::ID IID,Type * ReturnType,Value * Op0,Value * Op1,const SimplifyQuery & Q,const CallBase * Call)6458 Value *llvm::simplifyBinaryIntrinsic(Intrinsic::ID IID, Type *ReturnType,
6459                                      Value *Op0, Value *Op1,
6460                                      const SimplifyQuery &Q,
6461                                      const CallBase *Call) {
6462   unsigned BitWidth = ReturnType->getScalarSizeInBits();
6463   switch (IID) {
6464   case Intrinsic::abs:
6465     // abs(abs(x)) -> abs(x). We don't need to worry about the nsw arg here.
6466     // It is always ok to pick the earlier abs. We'll just lose nsw if its only
6467     // on the outer abs.
6468     if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(), m_Value())))
6469       return Op0;
6470     break;
6471 
6472   case Intrinsic::cttz: {
6473     Value *X;
6474     if (match(Op0, m_Shl(m_One(), m_Value(X))))
6475       return X;
6476     break;
6477   }
6478   case Intrinsic::ctlz: {
6479     Value *X;
6480     if (match(Op0, m_LShr(m_Negative(), m_Value(X))))
6481       return X;
6482     if (match(Op0, m_AShr(m_Negative(), m_Value())))
6483       return Constant::getNullValue(ReturnType);
6484     break;
6485   }
6486   case Intrinsic::ptrmask: {
6487     // NOTE: We can't apply this simplifications based on the value of Op1
6488     // because we need to preserve provenance.
6489     if (Q.isUndefValue(Op0) || match(Op0, m_Zero()))
6490       return Constant::getNullValue(Op0->getType());
6491 
6492     assert(Op1->getType()->getScalarSizeInBits() ==
6493                Q.DL.getIndexTypeSizeInBits(Op0->getType()) &&
6494            "Invalid mask width");
6495     // If index-width (mask size) is less than pointer-size then mask is
6496     // 1-extended.
6497     if (match(Op1, m_PtrToInt(m_Specific(Op0))))
6498       return Op0;
6499 
6500     // NOTE: We may have attributes associated with the return value of the
6501     // llvm.ptrmask intrinsic that will be lost when we just return the
6502     // operand. We should try to preserve them.
6503     if (match(Op1, m_AllOnes()) || Q.isUndefValue(Op1))
6504       return Op0;
6505 
6506     Constant *C;
6507     if (match(Op1, m_ImmConstant(C))) {
6508       KnownBits PtrKnown = computeKnownBits(Op0, Q);
6509       // See if we only masking off bits we know are already zero due to
6510       // alignment.
6511       APInt IrrelevantPtrBits =
6512           PtrKnown.Zero.zextOrTrunc(C->getType()->getScalarSizeInBits());
6513       C = ConstantFoldBinaryOpOperands(
6514           Instruction::Or, C, ConstantInt::get(C->getType(), IrrelevantPtrBits),
6515           Q.DL);
6516       if (C != nullptr && C->isAllOnesValue())
6517         return Op0;
6518     }
6519     break;
6520   }
6521   case Intrinsic::smax:
6522   case Intrinsic::smin:
6523   case Intrinsic::umax:
6524   case Intrinsic::umin: {
6525     // If the arguments are the same, this is a no-op.
6526     if (Op0 == Op1)
6527       return Op0;
6528 
6529     // Canonicalize immediate constant operand as Op1.
6530     if (match(Op0, m_ImmConstant()))
6531       std::swap(Op0, Op1);
6532 
6533     // Assume undef is the limit value.
6534     if (Q.isUndefValue(Op1))
6535       return ConstantInt::get(
6536           ReturnType, MinMaxIntrinsic::getSaturationPoint(IID, BitWidth));
6537 
6538     const APInt *C;
6539     if (match(Op1, m_APIntAllowPoison(C))) {
6540       // Clamp to limit value. For example:
6541       // umax(i8 %x, i8 255) --> 255
6542       if (*C == MinMaxIntrinsic::getSaturationPoint(IID, BitWidth))
6543         return ConstantInt::get(ReturnType, *C);
6544 
6545       // If the constant op is the opposite of the limit value, the other must
6546       // be larger/smaller or equal. For example:
6547       // umin(i8 %x, i8 255) --> %x
6548       if (*C == MinMaxIntrinsic::getSaturationPoint(
6549                     getInverseMinMaxIntrinsic(IID), BitWidth))
6550         return Op0;
6551 
6552       // Remove nested call if constant operands allow it. Example:
6553       // max (max X, 7), 5 -> max X, 7
6554       auto *MinMax0 = dyn_cast<IntrinsicInst>(Op0);
6555       if (MinMax0 && MinMax0->getIntrinsicID() == IID) {
6556         // TODO: loosen undef/splat restrictions for vector constants.
6557         Value *M00 = MinMax0->getOperand(0), *M01 = MinMax0->getOperand(1);
6558         const APInt *InnerC;
6559         if ((match(M00, m_APInt(InnerC)) || match(M01, m_APInt(InnerC))) &&
6560             ICmpInst::compare(*InnerC, *C,
6561                               ICmpInst::getNonStrictPredicate(
6562                                   MinMaxIntrinsic::getPredicate(IID))))
6563           return Op0;
6564       }
6565     }
6566 
6567     if (Value *V = foldMinMaxSharedOp(IID, Op0, Op1))
6568       return V;
6569     if (Value *V = foldMinMaxSharedOp(IID, Op1, Op0))
6570       return V;
6571 
6572     ICmpInst::Predicate Pred =
6573         ICmpInst::getNonStrictPredicate(MinMaxIntrinsic::getPredicate(IID));
6574     if (isICmpTrue(Pred, Op0, Op1, Q.getWithoutUndef(), RecursionLimit))
6575       return Op0;
6576     if (isICmpTrue(Pred, Op1, Op0, Q.getWithoutUndef(), RecursionLimit))
6577       return Op1;
6578 
6579     break;
6580   }
6581   case Intrinsic::scmp:
6582   case Intrinsic::ucmp: {
6583     // Fold to a constant if the relationship between operands can be
6584     // established with certainty
6585     if (isICmpTrue(CmpInst::ICMP_EQ, Op0, Op1, Q, RecursionLimit))
6586       return Constant::getNullValue(ReturnType);
6587 
6588     ICmpInst::Predicate PredGT =
6589         IID == Intrinsic::scmp ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
6590     if (isICmpTrue(PredGT, Op0, Op1, Q, RecursionLimit))
6591       return ConstantInt::get(ReturnType, 1);
6592 
6593     ICmpInst::Predicate PredLT =
6594         IID == Intrinsic::scmp ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
6595     if (isICmpTrue(PredLT, Op0, Op1, Q, RecursionLimit))
6596       return ConstantInt::getSigned(ReturnType, -1);
6597 
6598     break;
6599   }
6600   case Intrinsic::usub_with_overflow:
6601   case Intrinsic::ssub_with_overflow:
6602     // X - X -> { 0, false }
6603     // X - undef -> { 0, false }
6604     // undef - X -> { 0, false }
6605     if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
6606       return Constant::getNullValue(ReturnType);
6607     break;
6608   case Intrinsic::uadd_with_overflow:
6609   case Intrinsic::sadd_with_overflow:
6610     // X + undef -> { -1, false }
6611     // undef + x -> { -1, false }
6612     if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) {
6613       return ConstantStruct::get(
6614           cast<StructType>(ReturnType),
6615           {Constant::getAllOnesValue(ReturnType->getStructElementType(0)),
6616            Constant::getNullValue(ReturnType->getStructElementType(1))});
6617     }
6618     break;
6619   case Intrinsic::umul_with_overflow:
6620   case Intrinsic::smul_with_overflow:
6621     // 0 * X -> { 0, false }
6622     // X * 0 -> { 0, false }
6623     if (match(Op0, m_Zero()) || match(Op1, m_Zero()))
6624       return Constant::getNullValue(ReturnType);
6625     // undef * X -> { 0, false }
6626     // X * undef -> { 0, false }
6627     if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
6628       return Constant::getNullValue(ReturnType);
6629     break;
6630   case Intrinsic::uadd_sat:
6631     // sat(MAX + X) -> MAX
6632     // sat(X + MAX) -> MAX
6633     if (match(Op0, m_AllOnes()) || match(Op1, m_AllOnes()))
6634       return Constant::getAllOnesValue(ReturnType);
6635     [[fallthrough]];
6636   case Intrinsic::sadd_sat:
6637     // sat(X + undef) -> -1
6638     // sat(undef + X) -> -1
6639     // For unsigned: Assume undef is MAX, thus we saturate to MAX (-1).
6640     // For signed: Assume undef is ~X, in which case X + ~X = -1.
6641     if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
6642       return Constant::getAllOnesValue(ReturnType);
6643 
6644     // X + 0 -> X
6645     if (match(Op1, m_Zero()))
6646       return Op0;
6647     // 0 + X -> X
6648     if (match(Op0, m_Zero()))
6649       return Op1;
6650     break;
6651   case Intrinsic::usub_sat:
6652     // sat(0 - X) -> 0, sat(X - MAX) -> 0
6653     if (match(Op0, m_Zero()) || match(Op1, m_AllOnes()))
6654       return Constant::getNullValue(ReturnType);
6655     [[fallthrough]];
6656   case Intrinsic::ssub_sat:
6657     // X - X -> 0, X - undef -> 0, undef - X -> 0
6658     if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
6659       return Constant::getNullValue(ReturnType);
6660     // X - 0 -> X
6661     if (match(Op1, m_Zero()))
6662       return Op0;
6663     break;
6664   case Intrinsic::load_relative:
6665     if (auto *C0 = dyn_cast<Constant>(Op0))
6666       if (auto *C1 = dyn_cast<Constant>(Op1))
6667         return simplifyRelativeLoad(C0, C1, Q.DL);
6668     break;
6669   case Intrinsic::powi:
6670     if (auto *Power = dyn_cast<ConstantInt>(Op1)) {
6671       // powi(x, 0) -> 1.0
6672       if (Power->isZero())
6673         return ConstantFP::get(Op0->getType(), 1.0);
6674       // powi(x, 1) -> x
6675       if (Power->isOne())
6676         return Op0;
6677     }
6678     break;
6679   case Intrinsic::ldexp:
6680     return simplifyLdexp(Op0, Op1, Q, false);
6681   case Intrinsic::copysign:
6682     // copysign X, X --> X
6683     if (Op0 == Op1)
6684       return Op0;
6685     // copysign -X, X --> X
6686     // copysign X, -X --> -X
6687     if (match(Op0, m_FNeg(m_Specific(Op1))) ||
6688         match(Op1, m_FNeg(m_Specific(Op0))))
6689       return Op1;
6690     break;
6691   case Intrinsic::is_fpclass: {
6692     uint64_t Mask = cast<ConstantInt>(Op1)->getZExtValue();
6693     // If all tests are made, it doesn't matter what the value is.
6694     if ((Mask & fcAllFlags) == fcAllFlags)
6695       return ConstantInt::get(ReturnType, true);
6696     if ((Mask & fcAllFlags) == 0)
6697       return ConstantInt::get(ReturnType, false);
6698     if (Q.isUndefValue(Op0))
6699       return UndefValue::get(ReturnType);
6700     break;
6701   }
6702   case Intrinsic::maxnum:
6703   case Intrinsic::minnum:
6704   case Intrinsic::maximum:
6705   case Intrinsic::minimum: {
6706     // If the arguments are the same, this is a no-op.
6707     if (Op0 == Op1)
6708       return Op0;
6709 
6710     // Canonicalize constant operand as Op1.
6711     if (isa<Constant>(Op0))
6712       std::swap(Op0, Op1);
6713 
6714     // If an argument is undef, return the other argument.
6715     if (Q.isUndefValue(Op1))
6716       return Op0;
6717 
6718     bool PropagateNaN = IID == Intrinsic::minimum || IID == Intrinsic::maximum;
6719     bool IsMin = IID == Intrinsic::minimum || IID == Intrinsic::minnum;
6720 
6721     // minnum(X, nan) -> X
6722     // maxnum(X, nan) -> X
6723     // minimum(X, nan) -> nan
6724     // maximum(X, nan) -> nan
6725     if (match(Op1, m_NaN()))
6726       return PropagateNaN ? propagateNaN(cast<Constant>(Op1)) : Op0;
6727 
6728     // In the following folds, inf can be replaced with the largest finite
6729     // float, if the ninf flag is set.
6730     const APFloat *C;
6731     if (match(Op1, m_APFloat(C)) &&
6732         (C->isInfinity() || (Call && Call->hasNoInfs() && C->isLargest()))) {
6733       // minnum(X, -inf) -> -inf
6734       // maxnum(X, +inf) -> +inf
6735       // minimum(X, -inf) -> -inf if nnan
6736       // maximum(X, +inf) -> +inf if nnan
6737       if (C->isNegative() == IsMin &&
6738           (!PropagateNaN || (Call && Call->hasNoNaNs())))
6739         return ConstantFP::get(ReturnType, *C);
6740 
6741       // minnum(X, +inf) -> X if nnan
6742       // maxnum(X, -inf) -> X if nnan
6743       // minimum(X, +inf) -> X
6744       // maximum(X, -inf) -> X
6745       if (C->isNegative() != IsMin &&
6746           (PropagateNaN || (Call && Call->hasNoNaNs())))
6747         return Op0;
6748     }
6749 
6750     // Min/max of the same operation with common operand:
6751     // m(m(X, Y)), X --> m(X, Y) (4 commuted variants)
6752     if (Value *V = foldMinimumMaximumSharedOp(IID, Op0, Op1))
6753       return V;
6754     if (Value *V = foldMinimumMaximumSharedOp(IID, Op1, Op0))
6755       return V;
6756 
6757     break;
6758   }
6759   case Intrinsic::vector_extract: {
6760     // (extract_vector (insert_vector _, X, 0), 0) -> X
6761     unsigned IdxN = cast<ConstantInt>(Op1)->getZExtValue();
6762     Value *X = nullptr;
6763     if (match(Op0, m_Intrinsic<Intrinsic::vector_insert>(m_Value(), m_Value(X),
6764                                                          m_Zero())) &&
6765         IdxN == 0 && X->getType() == ReturnType)
6766       return X;
6767 
6768     break;
6769   }
6770   default:
6771     break;
6772   }
6773 
6774   return nullptr;
6775 }
6776 
simplifyIntrinsic(CallBase * Call,Value * Callee,ArrayRef<Value * > Args,const SimplifyQuery & Q)6777 static Value *simplifyIntrinsic(CallBase *Call, Value *Callee,
6778                                 ArrayRef<Value *> Args,
6779                                 const SimplifyQuery &Q) {
6780   // Operand bundles should not be in Args.
6781   assert(Call->arg_size() == Args.size());
6782   unsigned NumOperands = Args.size();
6783   Function *F = cast<Function>(Callee);
6784   Intrinsic::ID IID = F->getIntrinsicID();
6785 
6786   if (IID != Intrinsic::not_intrinsic && intrinsicPropagatesPoison(IID) &&
6787       any_of(Args, IsaPred<PoisonValue>))
6788     return PoisonValue::get(F->getReturnType());
6789   // Most of the intrinsics with no operands have some kind of side effect.
6790   // Don't simplify.
6791   if (!NumOperands) {
6792     switch (IID) {
6793     case Intrinsic::vscale: {
6794       Type *RetTy = F->getReturnType();
6795       ConstantRange CR = getVScaleRange(Call->getFunction(), 64);
6796       if (const APInt *C = CR.getSingleElement())
6797         return ConstantInt::get(RetTy, C->getZExtValue());
6798       return nullptr;
6799     }
6800     default:
6801       return nullptr;
6802     }
6803   }
6804 
6805   if (NumOperands == 1)
6806     return simplifyUnaryIntrinsic(F, Args[0], Q, Call);
6807 
6808   if (NumOperands == 2)
6809     return simplifyBinaryIntrinsic(IID, F->getReturnType(), Args[0], Args[1], Q,
6810                                    Call);
6811 
6812   // Handle intrinsics with 3 or more arguments.
6813   switch (IID) {
6814   case Intrinsic::masked_load:
6815   case Intrinsic::masked_gather: {
6816     Value *MaskArg = Args[2];
6817     Value *PassthruArg = Args[3];
6818     // If the mask is all zeros or undef, the "passthru" argument is the result.
6819     if (maskIsAllZeroOrUndef(MaskArg))
6820       return PassthruArg;
6821     return nullptr;
6822   }
6823   case Intrinsic::fshl:
6824   case Intrinsic::fshr: {
6825     Value *Op0 = Args[0], *Op1 = Args[1], *ShAmtArg = Args[2];
6826 
6827     // If both operands are undef, the result is undef.
6828     if (Q.isUndefValue(Op0) && Q.isUndefValue(Op1))
6829       return UndefValue::get(F->getReturnType());
6830 
6831     // If shift amount is undef, assume it is zero.
6832     if (Q.isUndefValue(ShAmtArg))
6833       return Args[IID == Intrinsic::fshl ? 0 : 1];
6834 
6835     const APInt *ShAmtC;
6836     if (match(ShAmtArg, m_APInt(ShAmtC))) {
6837       // If there's effectively no shift, return the 1st arg or 2nd arg.
6838       APInt BitWidth = APInt(ShAmtC->getBitWidth(), ShAmtC->getBitWidth());
6839       if (ShAmtC->urem(BitWidth).isZero())
6840         return Args[IID == Intrinsic::fshl ? 0 : 1];
6841     }
6842 
6843     // Rotating zero by anything is zero.
6844     if (match(Op0, m_Zero()) && match(Op1, m_Zero()))
6845       return ConstantInt::getNullValue(F->getReturnType());
6846 
6847     // Rotating -1 by anything is -1.
6848     if (match(Op0, m_AllOnes()) && match(Op1, m_AllOnes()))
6849       return ConstantInt::getAllOnesValue(F->getReturnType());
6850 
6851     return nullptr;
6852   }
6853   case Intrinsic::experimental_constrained_fma: {
6854     auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
6855     if (Value *V = simplifyFPOp(Args, {}, Q, *FPI->getExceptionBehavior(),
6856                                 *FPI->getRoundingMode()))
6857       return V;
6858     return nullptr;
6859   }
6860   case Intrinsic::fma:
6861   case Intrinsic::fmuladd: {
6862     if (Value *V = simplifyFPOp(Args, {}, Q, fp::ebIgnore,
6863                                 RoundingMode::NearestTiesToEven))
6864       return V;
6865     return nullptr;
6866   }
6867   case Intrinsic::smul_fix:
6868   case Intrinsic::smul_fix_sat: {
6869     Value *Op0 = Args[0];
6870     Value *Op1 = Args[1];
6871     Value *Op2 = Args[2];
6872     Type *ReturnType = F->getReturnType();
6873 
6874     // Canonicalize constant operand as Op1 (ConstantFolding handles the case
6875     // when both Op0 and Op1 are constant so we do not care about that special
6876     // case here).
6877     if (isa<Constant>(Op0))
6878       std::swap(Op0, Op1);
6879 
6880     // X * 0 -> 0
6881     if (match(Op1, m_Zero()))
6882       return Constant::getNullValue(ReturnType);
6883 
6884     // X * undef -> 0
6885     if (Q.isUndefValue(Op1))
6886       return Constant::getNullValue(ReturnType);
6887 
6888     // X * (1 << Scale) -> X
6889     APInt ScaledOne =
6890         APInt::getOneBitSet(ReturnType->getScalarSizeInBits(),
6891                             cast<ConstantInt>(Op2)->getZExtValue());
6892     if (ScaledOne.isNonNegative() && match(Op1, m_SpecificInt(ScaledOne)))
6893       return Op0;
6894 
6895     return nullptr;
6896   }
6897   case Intrinsic::vector_insert: {
6898     Value *Vec = Args[0];
6899     Value *SubVec = Args[1];
6900     Value *Idx = Args[2];
6901     Type *ReturnType = F->getReturnType();
6902 
6903     // (insert_vector Y, (extract_vector X, 0), 0) -> X
6904     // where: Y is X, or Y is undef
6905     unsigned IdxN = cast<ConstantInt>(Idx)->getZExtValue();
6906     Value *X = nullptr;
6907     if (match(SubVec,
6908               m_Intrinsic<Intrinsic::vector_extract>(m_Value(X), m_Zero())) &&
6909         (Q.isUndefValue(Vec) || Vec == X) && IdxN == 0 &&
6910         X->getType() == ReturnType)
6911       return X;
6912 
6913     return nullptr;
6914   }
6915   case Intrinsic::experimental_constrained_fadd: {
6916     auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
6917     return simplifyFAddInst(Args[0], Args[1], FPI->getFastMathFlags(), Q,
6918                             *FPI->getExceptionBehavior(),
6919                             *FPI->getRoundingMode());
6920   }
6921   case Intrinsic::experimental_constrained_fsub: {
6922     auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
6923     return simplifyFSubInst(Args[0], Args[1], FPI->getFastMathFlags(), Q,
6924                             *FPI->getExceptionBehavior(),
6925                             *FPI->getRoundingMode());
6926   }
6927   case Intrinsic::experimental_constrained_fmul: {
6928     auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
6929     return simplifyFMulInst(Args[0], Args[1], FPI->getFastMathFlags(), Q,
6930                             *FPI->getExceptionBehavior(),
6931                             *FPI->getRoundingMode());
6932   }
6933   case Intrinsic::experimental_constrained_fdiv: {
6934     auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
6935     return simplifyFDivInst(Args[0], Args[1], FPI->getFastMathFlags(), Q,
6936                             *FPI->getExceptionBehavior(),
6937                             *FPI->getRoundingMode());
6938   }
6939   case Intrinsic::experimental_constrained_frem: {
6940     auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
6941     return simplifyFRemInst(Args[0], Args[1], FPI->getFastMathFlags(), Q,
6942                             *FPI->getExceptionBehavior(),
6943                             *FPI->getRoundingMode());
6944   }
6945   case Intrinsic::experimental_constrained_ldexp:
6946     return simplifyLdexp(Args[0], Args[1], Q, true);
6947   case Intrinsic::experimental_gc_relocate: {
6948     GCRelocateInst &GCR = *cast<GCRelocateInst>(Call);
6949     Value *DerivedPtr = GCR.getDerivedPtr();
6950     Value *BasePtr = GCR.getBasePtr();
6951 
6952     // Undef is undef, even after relocation.
6953     if (isa<UndefValue>(DerivedPtr) || isa<UndefValue>(BasePtr)) {
6954       return UndefValue::get(GCR.getType());
6955     }
6956 
6957     if (auto *PT = dyn_cast<PointerType>(GCR.getType())) {
6958       // For now, the assumption is that the relocation of null will be null
6959       // for most any collector. If this ever changes, a corresponding hook
6960       // should be added to GCStrategy and this code should check it first.
6961       if (isa<ConstantPointerNull>(DerivedPtr)) {
6962         // Use null-pointer of gc_relocate's type to replace it.
6963         return ConstantPointerNull::get(PT);
6964       }
6965     }
6966     return nullptr;
6967   }
6968   case Intrinsic::experimental_vp_reverse: {
6969     Value *Vec = Call->getArgOperand(0);
6970     Value *Mask = Call->getArgOperand(1);
6971     Value *EVL = Call->getArgOperand(2);
6972 
6973     Value *X;
6974     // vp.reverse(vp.reverse(X)) == X (with all ones mask and matching EVL)
6975     if (match(Mask, m_AllOnes()) &&
6976         match(Vec, m_Intrinsic<Intrinsic::experimental_vp_reverse>(
6977                        m_Value(X), m_AllOnes(), m_Specific(EVL))))
6978       return X;
6979 
6980     // vp.reverse(splat(X)) -> splat(X) (regardless of mask and EVL)
6981     if (isSplatValue(Vec))
6982       return Vec;
6983     return nullptr;
6984   }
6985   default:
6986     return nullptr;
6987   }
6988 }
6989 
tryConstantFoldCall(CallBase * Call,Value * Callee,ArrayRef<Value * > Args,const SimplifyQuery & Q)6990 static Value *tryConstantFoldCall(CallBase *Call, Value *Callee,
6991                                   ArrayRef<Value *> Args,
6992                                   const SimplifyQuery &Q) {
6993   auto *F = dyn_cast<Function>(Callee);
6994   if (!F || !canConstantFoldCallTo(Call, F))
6995     return nullptr;
6996 
6997   SmallVector<Constant *, 4> ConstantArgs;
6998   ConstantArgs.reserve(Args.size());
6999   for (Value *Arg : Args) {
7000     Constant *C = dyn_cast<Constant>(Arg);
7001     if (!C) {
7002       if (isa<MetadataAsValue>(Arg))
7003         continue;
7004       return nullptr;
7005     }
7006     ConstantArgs.push_back(C);
7007   }
7008 
7009   return ConstantFoldCall(Call, F, ConstantArgs, Q.TLI);
7010 }
7011 
simplifyCall(CallBase * Call,Value * Callee,ArrayRef<Value * > Args,const SimplifyQuery & Q)7012 Value *llvm::simplifyCall(CallBase *Call, Value *Callee, ArrayRef<Value *> Args,
7013                           const SimplifyQuery &Q) {
7014   // Args should not contain operand bundle operands.
7015   assert(Call->arg_size() == Args.size());
7016 
7017   // musttail calls can only be simplified if they are also DCEd.
7018   // As we can't guarantee this here, don't simplify them.
7019   if (Call->isMustTailCall())
7020     return nullptr;
7021 
7022   // call undef -> poison
7023   // call null -> poison
7024   if (isa<UndefValue>(Callee) || isa<ConstantPointerNull>(Callee))
7025     return PoisonValue::get(Call->getType());
7026 
7027   if (Value *V = tryConstantFoldCall(Call, Callee, Args, Q))
7028     return V;
7029 
7030   auto *F = dyn_cast<Function>(Callee);
7031   if (F && F->isIntrinsic())
7032     if (Value *Ret = simplifyIntrinsic(Call, Callee, Args, Q))
7033       return Ret;
7034 
7035   return nullptr;
7036 }
7037 
simplifyConstrainedFPCall(CallBase * Call,const SimplifyQuery & Q)7038 Value *llvm::simplifyConstrainedFPCall(CallBase *Call, const SimplifyQuery &Q) {
7039   assert(isa<ConstrainedFPIntrinsic>(Call));
7040   SmallVector<Value *, 4> Args(Call->args());
7041   if (Value *V = tryConstantFoldCall(Call, Call->getCalledOperand(), Args, Q))
7042     return V;
7043   if (Value *Ret = simplifyIntrinsic(Call, Call->getCalledOperand(), Args, Q))
7044     return Ret;
7045   return nullptr;
7046 }
7047 
7048 /// Given operands for a Freeze, see if we can fold the result.
simplifyFreezeInst(Value * Op0,const SimplifyQuery & Q)7049 static Value *simplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) {
7050   // Use a utility function defined in ValueTracking.
7051   if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT))
7052     return Op0;
7053   // We have room for improvement.
7054   return nullptr;
7055 }
7056 
simplifyFreezeInst(Value * Op0,const SimplifyQuery & Q)7057 Value *llvm::simplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) {
7058   return ::simplifyFreezeInst(Op0, Q);
7059 }
7060 
simplifyLoadInst(LoadInst * LI,Value * PtrOp,const SimplifyQuery & Q)7061 Value *llvm::simplifyLoadInst(LoadInst *LI, Value *PtrOp,
7062                               const SimplifyQuery &Q) {
7063   if (LI->isVolatile())
7064     return nullptr;
7065 
7066   if (auto *PtrOpC = dyn_cast<Constant>(PtrOp))
7067     return ConstantFoldLoadFromConstPtr(PtrOpC, LI->getType(), Q.DL);
7068 
7069   // We can only fold the load if it is from a constant global with definitive
7070   // initializer. Skip expensive logic if this is not the case.
7071   auto *GV = dyn_cast<GlobalVariable>(getUnderlyingObject(PtrOp));
7072   if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer())
7073     return nullptr;
7074 
7075   // If GlobalVariable's initializer is uniform, then return the constant
7076   // regardless of its offset.
7077   if (Constant *C = ConstantFoldLoadFromUniformValue(GV->getInitializer(),
7078                                                      LI->getType(), Q.DL))
7079     return C;
7080 
7081   // Try to convert operand into a constant by stripping offsets while looking
7082   // through invariant.group intrinsics.
7083   APInt Offset(Q.DL.getIndexTypeSizeInBits(PtrOp->getType()), 0);
7084   PtrOp = PtrOp->stripAndAccumulateConstantOffsets(
7085       Q.DL, Offset, /* AllowNonInbounts */ true,
7086       /* AllowInvariantGroup */ true);
7087   if (PtrOp == GV) {
7088     // Index size may have changed due to address space casts.
7089     Offset = Offset.sextOrTrunc(Q.DL.getIndexTypeSizeInBits(PtrOp->getType()));
7090     return ConstantFoldLoadFromConstPtr(GV, LI->getType(), std::move(Offset),
7091                                         Q.DL);
7092   }
7093 
7094   return nullptr;
7095 }
7096 
7097 /// See if we can compute a simplified version of this instruction.
7098 /// If not, this returns null.
7099 
simplifyInstructionWithOperands(Instruction * I,ArrayRef<Value * > NewOps,const SimplifyQuery & SQ,unsigned MaxRecurse)7100 static Value *simplifyInstructionWithOperands(Instruction *I,
7101                                               ArrayRef<Value *> NewOps,
7102                                               const SimplifyQuery &SQ,
7103                                               unsigned MaxRecurse) {
7104   assert(I->getFunction() && "instruction should be inserted in a function");
7105   assert((!SQ.CxtI || SQ.CxtI->getFunction() == I->getFunction()) &&
7106          "context instruction should be in the same function");
7107 
7108   const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I);
7109 
7110   switch (I->getOpcode()) {
7111   default:
7112     if (llvm::all_of(NewOps, [](Value *V) { return isa<Constant>(V); })) {
7113       SmallVector<Constant *, 8> NewConstOps(NewOps.size());
7114       transform(NewOps, NewConstOps.begin(),
7115                 [](Value *V) { return cast<Constant>(V); });
7116       return ConstantFoldInstOperands(I, NewConstOps, Q.DL, Q.TLI);
7117     }
7118     return nullptr;
7119   case Instruction::FNeg:
7120     return simplifyFNegInst(NewOps[0], I->getFastMathFlags(), Q, MaxRecurse);
7121   case Instruction::FAdd:
7122     return simplifyFAddInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q,
7123                             MaxRecurse);
7124   case Instruction::Add:
7125     return simplifyAddInst(
7126         NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
7127         Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse);
7128   case Instruction::FSub:
7129     return simplifyFSubInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q,
7130                             MaxRecurse);
7131   case Instruction::Sub:
7132     return simplifySubInst(
7133         NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
7134         Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse);
7135   case Instruction::FMul:
7136     return simplifyFMulInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q,
7137                             MaxRecurse);
7138   case Instruction::Mul:
7139     return simplifyMulInst(
7140         NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
7141         Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse);
7142   case Instruction::SDiv:
7143     return simplifySDivInst(NewOps[0], NewOps[1],
7144                             Q.IIQ.isExact(cast<BinaryOperator>(I)), Q,
7145                             MaxRecurse);
7146   case Instruction::UDiv:
7147     return simplifyUDivInst(NewOps[0], NewOps[1],
7148                             Q.IIQ.isExact(cast<BinaryOperator>(I)), Q,
7149                             MaxRecurse);
7150   case Instruction::FDiv:
7151     return simplifyFDivInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q,
7152                             MaxRecurse);
7153   case Instruction::SRem:
7154     return simplifySRemInst(NewOps[0], NewOps[1], Q, MaxRecurse);
7155   case Instruction::URem:
7156     return simplifyURemInst(NewOps[0], NewOps[1], Q, MaxRecurse);
7157   case Instruction::FRem:
7158     return simplifyFRemInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q,
7159                             MaxRecurse);
7160   case Instruction::Shl:
7161     return simplifyShlInst(
7162         NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
7163         Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse);
7164   case Instruction::LShr:
7165     return simplifyLShrInst(NewOps[0], NewOps[1],
7166                             Q.IIQ.isExact(cast<BinaryOperator>(I)), Q,
7167                             MaxRecurse);
7168   case Instruction::AShr:
7169     return simplifyAShrInst(NewOps[0], NewOps[1],
7170                             Q.IIQ.isExact(cast<BinaryOperator>(I)), Q,
7171                             MaxRecurse);
7172   case Instruction::And:
7173     return simplifyAndInst(NewOps[0], NewOps[1], Q, MaxRecurse);
7174   case Instruction::Or:
7175     return simplifyOrInst(NewOps[0], NewOps[1], Q, MaxRecurse);
7176   case Instruction::Xor:
7177     return simplifyXorInst(NewOps[0], NewOps[1], Q, MaxRecurse);
7178   case Instruction::ICmp:
7179     return simplifyICmpInst(cast<ICmpInst>(I)->getCmpPredicate(), NewOps[0],
7180                             NewOps[1], Q, MaxRecurse);
7181   case Instruction::FCmp:
7182     return simplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), NewOps[0],
7183                             NewOps[1], I->getFastMathFlags(), Q, MaxRecurse);
7184   case Instruction::Select:
7185     return simplifySelectInst(NewOps[0], NewOps[1], NewOps[2], Q, MaxRecurse);
7186   case Instruction::GetElementPtr: {
7187     auto *GEPI = cast<GetElementPtrInst>(I);
7188     return simplifyGEPInst(GEPI->getSourceElementType(), NewOps[0],
7189                            ArrayRef(NewOps).slice(1), GEPI->getNoWrapFlags(), Q,
7190                            MaxRecurse);
7191   }
7192   case Instruction::InsertValue: {
7193     InsertValueInst *IV = cast<InsertValueInst>(I);
7194     return simplifyInsertValueInst(NewOps[0], NewOps[1], IV->getIndices(), Q,
7195                                    MaxRecurse);
7196   }
7197   case Instruction::InsertElement:
7198     return simplifyInsertElementInst(NewOps[0], NewOps[1], NewOps[2], Q);
7199   case Instruction::ExtractValue: {
7200     auto *EVI = cast<ExtractValueInst>(I);
7201     return simplifyExtractValueInst(NewOps[0], EVI->getIndices(), Q,
7202                                     MaxRecurse);
7203   }
7204   case Instruction::ExtractElement:
7205     return simplifyExtractElementInst(NewOps[0], NewOps[1], Q, MaxRecurse);
7206   case Instruction::ShuffleVector: {
7207     auto *SVI = cast<ShuffleVectorInst>(I);
7208     return simplifyShuffleVectorInst(NewOps[0], NewOps[1],
7209                                      SVI->getShuffleMask(), SVI->getType(), Q,
7210                                      MaxRecurse);
7211   }
7212   case Instruction::PHI:
7213     return simplifyPHINode(cast<PHINode>(I), NewOps, Q);
7214   case Instruction::Call:
7215     return simplifyCall(
7216         cast<CallInst>(I), NewOps.back(),
7217         NewOps.drop_back(1 + cast<CallInst>(I)->getNumTotalBundleOperands()), Q);
7218   case Instruction::Freeze:
7219     return llvm::simplifyFreezeInst(NewOps[0], Q);
7220 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc:
7221 #include "llvm/IR/Instruction.def"
7222 #undef HANDLE_CAST_INST
7223     return simplifyCastInst(I->getOpcode(), NewOps[0], I->getType(), Q,
7224                             MaxRecurse);
7225   case Instruction::Alloca:
7226     // No simplifications for Alloca and it can't be constant folded.
7227     return nullptr;
7228   case Instruction::Load:
7229     return simplifyLoadInst(cast<LoadInst>(I), NewOps[0], Q);
7230   }
7231 }
7232 
simplifyInstructionWithOperands(Instruction * I,ArrayRef<Value * > NewOps,const SimplifyQuery & SQ)7233 Value *llvm::simplifyInstructionWithOperands(Instruction *I,
7234                                              ArrayRef<Value *> NewOps,
7235                                              const SimplifyQuery &SQ) {
7236   assert(NewOps.size() == I->getNumOperands() &&
7237          "Number of operands should match the instruction!");
7238   return ::simplifyInstructionWithOperands(I, NewOps, SQ, RecursionLimit);
7239 }
7240 
simplifyInstruction(Instruction * I,const SimplifyQuery & SQ)7241 Value *llvm::simplifyInstruction(Instruction *I, const SimplifyQuery &SQ) {
7242   SmallVector<Value *, 8> Ops(I->operands());
7243   Value *Result = ::simplifyInstructionWithOperands(I, Ops, SQ, RecursionLimit);
7244 
7245   /// If called on unreachable code, the instruction may simplify to itself.
7246   /// Make life easier for users by detecting that case here, and returning a
7247   /// safe value instead.
7248   return Result == I ? PoisonValue::get(I->getType()) : Result;
7249 }
7250 
7251 /// Implementation of recursive simplification through an instruction's
7252 /// uses.
7253 ///
7254 /// This is the common implementation of the recursive simplification routines.
7255 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
7256 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
7257 /// instructions to process and attempt to simplify it using
7258 /// InstructionSimplify. Recursively visited users which could not be
7259 /// simplified themselves are to the optional UnsimplifiedUsers set for
7260 /// further processing by the caller.
7261 ///
7262 /// This routine returns 'true' only when *it* simplifies something. The passed
7263 /// in simplified value does not count toward this.
replaceAndRecursivelySimplifyImpl(Instruction * I,Value * SimpleV,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,SmallSetVector<Instruction *,8> * UnsimplifiedUsers=nullptr)7264 static bool replaceAndRecursivelySimplifyImpl(
7265     Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI,
7266     const DominatorTree *DT, AssumptionCache *AC,
7267     SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) {
7268   bool Simplified = false;
7269   SmallSetVector<Instruction *, 8> Worklist;
7270   const DataLayout &DL = I->getDataLayout();
7271 
7272   // If we have an explicit value to collapse to, do that round of the
7273   // simplification loop by hand initially.
7274   if (SimpleV) {
7275     for (User *U : I->users())
7276       if (U != I)
7277         Worklist.insert(cast<Instruction>(U));
7278 
7279     // Replace the instruction with its simplified value.
7280     I->replaceAllUsesWith(SimpleV);
7281 
7282     if (!I->isEHPad() && !I->isTerminator() && !I->mayHaveSideEffects())
7283       I->eraseFromParent();
7284   } else {
7285     Worklist.insert(I);
7286   }
7287 
7288   // Note that we must test the size on each iteration, the worklist can grow.
7289   for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
7290     I = Worklist[Idx];
7291 
7292     // See if this instruction simplifies.
7293     SimpleV = simplifyInstruction(I, {DL, TLI, DT, AC});
7294     if (!SimpleV) {
7295       if (UnsimplifiedUsers)
7296         UnsimplifiedUsers->insert(I);
7297       continue;
7298     }
7299 
7300     Simplified = true;
7301 
7302     // Stash away all the uses of the old instruction so we can check them for
7303     // recursive simplifications after a RAUW. This is cheaper than checking all
7304     // uses of To on the recursive step in most cases.
7305     for (User *U : I->users())
7306       Worklist.insert(cast<Instruction>(U));
7307 
7308     // Replace the instruction with its simplified value.
7309     I->replaceAllUsesWith(SimpleV);
7310 
7311     if (!I->isEHPad() && !I->isTerminator() && !I->mayHaveSideEffects())
7312       I->eraseFromParent();
7313   }
7314   return Simplified;
7315 }
7316 
replaceAndRecursivelySimplify(Instruction * I,Value * SimpleV,const TargetLibraryInfo * TLI,const DominatorTree * DT,AssumptionCache * AC,SmallSetVector<Instruction *,8> * UnsimplifiedUsers)7317 bool llvm::replaceAndRecursivelySimplify(
7318     Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI,
7319     const DominatorTree *DT, AssumptionCache *AC,
7320     SmallSetVector<Instruction *, 8> *UnsimplifiedUsers) {
7321   assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
7322   assert(SimpleV && "Must provide a simplified value.");
7323   return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC,
7324                                            UnsimplifiedUsers);
7325 }
7326 
7327 namespace llvm {
getBestSimplifyQuery(Pass & P,Function & F)7328 const SimplifyQuery getBestSimplifyQuery(Pass &P, Function &F) {
7329   auto *DTWP = P.getAnalysisIfAvailable<DominatorTreeWrapperPass>();
7330   auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
7331   auto *TLIWP = P.getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
7332   auto *TLI = TLIWP ? &TLIWP->getTLI(F) : nullptr;
7333   auto *ACWP = P.getAnalysisIfAvailable<AssumptionCacheTracker>();
7334   auto *AC = ACWP ? &ACWP->getAssumptionCache(F) : nullptr;
7335   return {F.getDataLayout(), TLI, DT, AC};
7336 }
7337 
getBestSimplifyQuery(LoopStandardAnalysisResults & AR,const DataLayout & DL)7338 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &AR,
7339                                          const DataLayout &DL) {
7340   return {DL, &AR.TLI, &AR.DT, &AR.AC};
7341 }
7342 
7343 template <class T, class... TArgs>
getBestSimplifyQuery(AnalysisManager<T,TArgs...> & AM,Function & F)7344 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &AM,
7345                                          Function &F) {
7346   auto *DT = AM.template getCachedResult<DominatorTreeAnalysis>(F);
7347   auto *TLI = AM.template getCachedResult<TargetLibraryAnalysis>(F);
7348   auto *AC = AM.template getCachedResult<AssumptionAnalysis>(F);
7349   return {F.getDataLayout(), TLI, DT, AC};
7350 }
7351 template const SimplifyQuery getBestSimplifyQuery(AnalysisManager<Function> &,
7352                                                   Function &);
7353 
isUndefValue(Value * V) const7354 bool SimplifyQuery::isUndefValue(Value *V) const {
7355   if (!CanUseUndef)
7356     return false;
7357 
7358   return match(V, m_Undef());
7359 }
7360 
7361 } // namespace llvm
7362 
anchor()7363 void InstSimplifyFolder::anchor() {}
7364