LLVM  12.0.0git
InstCombineSelect.cpp
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1 //===- InstCombineSelect.cpp ----------------------------------------------===//
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 the visitSelect function.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "InstCombineInternal.h"
14 #include "llvm/ADT/APInt.h"
15 #include "llvm/ADT/Optional.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/IR/BasicBlock.h"
23 #include "llvm/IR/Constant.h"
24 #include "llvm/IR/Constants.h"
25 #include "llvm/IR/DerivedTypes.h"
26 #include "llvm/IR/IRBuilder.h"
27 #include "llvm/IR/InstrTypes.h"
28 #include "llvm/IR/Instruction.h"
29 #include "llvm/IR/Instructions.h"
30 #include "llvm/IR/IntrinsicInst.h"
31 #include "llvm/IR/Intrinsics.h"
32 #include "llvm/IR/Operator.h"
33 #include "llvm/IR/PatternMatch.h"
34 #include "llvm/IR/Type.h"
35 #include "llvm/IR/User.h"
36 #include "llvm/IR/Value.h"
37 #include "llvm/Support/Casting.h"
39 #include "llvm/Support/KnownBits.h"
41 #include <cassert>
42 #include <utility>
43 
44 using namespace llvm;
45 using namespace PatternMatch;
46 
47 #define DEBUG_TYPE "instcombine"
48 
50  SelectPatternFlavor SPF, Value *A, Value *B) {
52  assert(CmpInst::isIntPredicate(Pred) && "Expected integer predicate");
53  return Builder.CreateSelect(Builder.CreateICmp(Pred, A, B), A, B);
54 }
55 
56 /// Replace a select operand based on an equality comparison with the identity
57 /// constant of a binop.
59  const TargetLibraryInfo &TLI,
60  InstCombiner &IC) {
61  // The select condition must be an equality compare with a constant operand.
62  Value *X;
63  Constant *C;
64  CmpInst::Predicate Pred;
65  if (!match(Sel.getCondition(), m_Cmp(Pred, m_Value(X), m_Constant(C))))
66  return nullptr;
67 
68  bool IsEq;
69  if (ICmpInst::isEquality(Pred))
70  IsEq = Pred == ICmpInst::ICMP_EQ;
71  else if (Pred == FCmpInst::FCMP_OEQ)
72  IsEq = true;
73  else if (Pred == FCmpInst::FCMP_UNE)
74  IsEq = false;
75  else
76  return nullptr;
77 
78  // A select operand must be a binop.
79  BinaryOperator *BO;
80  if (!match(Sel.getOperand(IsEq ? 1 : 2), m_BinOp(BO)))
81  return nullptr;
82 
83  // The compare constant must be the identity constant for that binop.
84  // If this a floating-point compare with 0.0, any zero constant will do.
85  Type *Ty = BO->getType();
86  Constant *IdC = ConstantExpr::getBinOpIdentity(BO->getOpcode(), Ty, true);
87  if (IdC != C) {
88  if (!IdC || !CmpInst::isFPPredicate(Pred))
89  return nullptr;
90  if (!match(IdC, m_AnyZeroFP()) || !match(C, m_AnyZeroFP()))
91  return nullptr;
92  }
93 
94  // Last, match the compare variable operand with a binop operand.
95  Value *Y;
96  if (!BO->isCommutative() && !match(BO, m_BinOp(m_Value(Y), m_Specific(X))))
97  return nullptr;
98  if (!match(BO, m_c_BinOp(m_Value(Y), m_Specific(X))))
99  return nullptr;
100 
101  // +0.0 compares equal to -0.0, and so it does not behave as required for this
102  // transform. Bail out if we can not exclude that possibility.
103  if (isa<FPMathOperator>(BO))
104  if (!BO->hasNoSignedZeros() && !CannotBeNegativeZero(Y, &TLI))
105  return nullptr;
106 
107  // BO = binop Y, X
108  // S = { select (cmp eq X, C), BO, ? } or { select (cmp ne X, C), ?, BO }
109  // =>
110  // S = { select (cmp eq X, C), Y, ? } or { select (cmp ne X, C), ?, Y }
111  return IC.replaceOperand(Sel, IsEq ? 1 : 2, Y);
112 }
113 
114 /// This folds:
115 /// select (icmp eq (and X, C1)), TC, FC
116 /// iff C1 is a power 2 and the difference between TC and FC is a power-of-2.
117 /// To something like:
118 /// (shr (and (X, C1)), (log2(C1) - log2(TC-FC))) + FC
119 /// Or:
120 /// (shl (and (X, C1)), (log2(TC-FC) - log2(C1))) + FC
121 /// With some variations depending if FC is larger than TC, or the shift
122 /// isn't needed, or the bit widths don't match.
125  const APInt *SelTC, *SelFC;
126  if (!match(Sel.getTrueValue(), m_APInt(SelTC)) ||
127  !match(Sel.getFalseValue(), m_APInt(SelFC)))
128  return nullptr;
129 
130  // If this is a vector select, we need a vector compare.
131  Type *SelType = Sel.getType();
132  if (SelType->isVectorTy() != Cmp->getType()->isVectorTy())
133  return nullptr;
134 
135  Value *V;
136  APInt AndMask;
137  bool CreateAnd = false;
138  ICmpInst::Predicate Pred = Cmp->getPredicate();
139  if (ICmpInst::isEquality(Pred)) {
140  if (!match(Cmp->getOperand(1), m_Zero()))
141  return nullptr;
142 
143  V = Cmp->getOperand(0);
144  const APInt *AndRHS;
145  if (!match(V, m_And(m_Value(), m_Power2(AndRHS))))
146  return nullptr;
147 
148  AndMask = *AndRHS;
149  } else if (decomposeBitTestICmp(Cmp->getOperand(0), Cmp->getOperand(1),
150  Pred, V, AndMask)) {
151  assert(ICmpInst::isEquality(Pred) && "Not equality test?");
152  if (!AndMask.isPowerOf2())
153  return nullptr;
154 
155  CreateAnd = true;
156  } else {
157  return nullptr;
158  }
159 
160  // In general, when both constants are non-zero, we would need an offset to
161  // replace the select. This would require more instructions than we started
162  // with. But there's one special-case that we handle here because it can
163  // simplify/reduce the instructions.
164  APInt TC = *SelTC;
165  APInt FC = *SelFC;
166  if (!TC.isNullValue() && !FC.isNullValue()) {
167  // If the select constants differ by exactly one bit and that's the same
168  // bit that is masked and checked by the select condition, the select can
169  // be replaced by bitwise logic to set/clear one bit of the constant result.
170  if (TC.getBitWidth() != AndMask.getBitWidth() || (TC ^ FC) != AndMask)
171  return nullptr;
172  if (CreateAnd) {
173  // If we have to create an 'and', then we must kill the cmp to not
174  // increase the instruction count.
175  if (!Cmp->hasOneUse())
176  return nullptr;
177  V = Builder.CreateAnd(V, ConstantInt::get(SelType, AndMask));
178  }
179  bool ExtraBitInTC = TC.ugt(FC);
180  if (Pred == ICmpInst::ICMP_EQ) {
181  // If the masked bit in V is clear, clear or set the bit in the result:
182  // (V & AndMaskC) == 0 ? TC : FC --> (V & AndMaskC) ^ TC
183  // (V & AndMaskC) == 0 ? TC : FC --> (V & AndMaskC) | TC
184  Constant *C = ConstantInt::get(SelType, TC);
185  return ExtraBitInTC ? Builder.CreateXor(V, C) : Builder.CreateOr(V, C);
186  }
187  if (Pred == ICmpInst::ICMP_NE) {
188  // If the masked bit in V is set, set or clear the bit in the result:
189  // (V & AndMaskC) != 0 ? TC : FC --> (V & AndMaskC) | FC
190  // (V & AndMaskC) != 0 ? TC : FC --> (V & AndMaskC) ^ FC
191  Constant *C = ConstantInt::get(SelType, FC);
192  return ExtraBitInTC ? Builder.CreateOr(V, C) : Builder.CreateXor(V, C);
193  }
194  llvm_unreachable("Only expecting equality predicates");
195  }
196 
197  // Make sure one of the select arms is a power-of-2.
198  if (!TC.isPowerOf2() && !FC.isPowerOf2())
199  return nullptr;
200 
201  // Determine which shift is needed to transform result of the 'and' into the
202  // desired result.
203  const APInt &ValC = !TC.isNullValue() ? TC : FC;
204  unsigned ValZeros = ValC.logBase2();
205  unsigned AndZeros = AndMask.logBase2();
206 
207  // Insert the 'and' instruction on the input to the truncate.
208  if (CreateAnd)
209  V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), AndMask));
210 
211  // If types don't match, we can still convert the select by introducing a zext
212  // or a trunc of the 'and'.
213  if (ValZeros > AndZeros) {
214  V = Builder.CreateZExtOrTrunc(V, SelType);
215  V = Builder.CreateShl(V, ValZeros - AndZeros);
216  } else if (ValZeros < AndZeros) {
217  V = Builder.CreateLShr(V, AndZeros - ValZeros);
218  V = Builder.CreateZExtOrTrunc(V, SelType);
219  } else {
220  V = Builder.CreateZExtOrTrunc(V, SelType);
221  }
222 
223  // Okay, now we know that everything is set up, we just don't know whether we
224  // have a icmp_ne or icmp_eq and whether the true or false val is the zero.
225  bool ShouldNotVal = !TC.isNullValue();
226  ShouldNotVal ^= Pred == ICmpInst::ICMP_NE;
227  if (ShouldNotVal)
228  V = Builder.CreateXor(V, ValC);
229 
230  return V;
231 }
232 
233 /// We want to turn code that looks like this:
234 /// %C = or %A, %B
235 /// %D = select %cond, %C, %A
236 /// into:
237 /// %C = select %cond, %B, 0
238 /// %D = or %A, %C
239 ///
240 /// Assuming that the specified instruction is an operand to the select, return
241 /// a bitmask indicating which operands of this instruction are foldable if they
242 /// equal the other incoming value of the select.
244  switch (I->getOpcode()) {
245  case Instruction::Add:
246  case Instruction::Mul:
247  case Instruction::And:
248  case Instruction::Or:
249  case Instruction::Xor:
250  return 3; // Can fold through either operand.
251  case Instruction::Sub: // Can only fold on the amount subtracted.
252  case Instruction::Shl: // Can only fold on the shift amount.
253  case Instruction::LShr:
254  case Instruction::AShr:
255  return 1;
256  default:
257  return 0; // Cannot fold
258  }
259 }
260 
261 /// For the same transformation as the previous function, return the identity
262 /// constant that goes into the select.
264  switch (I->getOpcode()) {
265  default: llvm_unreachable("This cannot happen!");
266  case Instruction::Add:
267  case Instruction::Sub:
268  case Instruction::Or:
269  case Instruction::Xor:
270  case Instruction::Shl:
271  case Instruction::LShr:
272  case Instruction::AShr:
274  case Instruction::And:
276  case Instruction::Mul:
277  return APInt(I->getType()->getScalarSizeInBits(), 1);
278  }
279 }
280 
281 /// We have (select c, TI, FI), and we know that TI and FI have the same opcode.
282 Instruction *InstCombiner::foldSelectOpOp(SelectInst &SI, Instruction *TI,
283  Instruction *FI) {
284  // Don't break up min/max patterns. The hasOneUse checks below prevent that
285  // for most cases, but vector min/max with bitcasts can be transformed. If the
286  // one-use restrictions are eased for other patterns, we still don't want to
287  // obfuscate min/max.
288  if ((match(&SI, m_SMin(m_Value(), m_Value())) ||
289  match(&SI, m_SMax(m_Value(), m_Value())) ||
290  match(&SI, m_UMin(m_Value(), m_Value())) ||
291  match(&SI, m_UMax(m_Value(), m_Value()))))
292  return nullptr;
293 
294  // If this is a cast from the same type, merge.
295  Value *Cond = SI.getCondition();
296  Type *CondTy = Cond->getType();
297  if (TI->getNumOperands() == 1 && TI->isCast()) {
298  Type *FIOpndTy = FI->getOperand(0)->getType();
299  if (TI->getOperand(0)->getType() != FIOpndTy)
300  return nullptr;
301 
302  // The select condition may be a vector. We may only change the operand
303  // type if the vector width remains the same (and matches the condition).
304  if (auto *CondVTy = dyn_cast<VectorType>(CondTy)) {
305  if (!FIOpndTy->isVectorTy())
306  return nullptr;
307  if (CondVTy->getNumElements() !=
308  cast<VectorType>(FIOpndTy)->getNumElements())
309  return nullptr;
310 
311  // TODO: If the backend knew how to deal with casts better, we could
312  // remove this limitation. For now, there's too much potential to create
313  // worse codegen by promoting the select ahead of size-altering casts
314  // (PR28160).
315  //
316  // Note that ValueTracking's matchSelectPattern() looks through casts
317  // without checking 'hasOneUse' when it matches min/max patterns, so this
318  // transform may end up happening anyway.
319  if (TI->getOpcode() != Instruction::BitCast &&
320  (!TI->hasOneUse() || !FI->hasOneUse()))
321  return nullptr;
322  } else if (!TI->hasOneUse() || !FI->hasOneUse()) {
323  // TODO: The one-use restrictions for a scalar select could be eased if
324  // the fold of a select in visitLoadInst() was enhanced to match a pattern
325  // that includes a cast.
326  return nullptr;
327  }
328 
329  // Fold this by inserting a select from the input values.
330  Value *NewSI =
331  Builder.CreateSelect(Cond, TI->getOperand(0), FI->getOperand(0),
332  SI.getName() + ".v", &SI);
333  return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
334  TI->getType());
335  }
336 
337  // Cond ? -X : -Y --> -(Cond ? X : Y)
338  Value *X, *Y;
339  if (match(TI, m_FNeg(m_Value(X))) && match(FI, m_FNeg(m_Value(Y))) &&
340  (TI->hasOneUse() || FI->hasOneUse())) {
341  Value *NewSel = Builder.CreateSelect(Cond, X, Y, SI.getName() + ".v", &SI);
342  return UnaryOperator::CreateFNegFMF(NewSel, TI);
343  }
344 
345  // Only handle binary operators (including two-operand getelementptr) with
346  // one-use here. As with the cast case above, it may be possible to relax the
347  // one-use constraint, but that needs be examined carefully since it may not
348  // reduce the total number of instructions.
349  if (TI->getNumOperands() != 2 || FI->getNumOperands() != 2 ||
350  (!isa<BinaryOperator>(TI) && !isa<GetElementPtrInst>(TI)) ||
351  !TI->hasOneUse() || !FI->hasOneUse())
352  return nullptr;
353 
354  // Figure out if the operations have any operands in common.
355  Value *MatchOp, *OtherOpT, *OtherOpF;
356  bool MatchIsOpZero;
357  if (TI->getOperand(0) == FI->getOperand(0)) {
358  MatchOp = TI->getOperand(0);
359  OtherOpT = TI->getOperand(1);
360  OtherOpF = FI->getOperand(1);
361  MatchIsOpZero = true;
362  } else if (TI->getOperand(1) == FI->getOperand(1)) {
363  MatchOp = TI->getOperand(1);
364  OtherOpT = TI->getOperand(0);
365  OtherOpF = FI->getOperand(0);
366  MatchIsOpZero = false;
367  } else if (!TI->isCommutative()) {
368  return nullptr;
369  } else if (TI->getOperand(0) == FI->getOperand(1)) {
370  MatchOp = TI->getOperand(0);
371  OtherOpT = TI->getOperand(1);
372  OtherOpF = FI->getOperand(0);
373  MatchIsOpZero = true;
374  } else if (TI->getOperand(1) == FI->getOperand(0)) {
375  MatchOp = TI->getOperand(1);
376  OtherOpT = TI->getOperand(0);
377  OtherOpF = FI->getOperand(1);
378  MatchIsOpZero = true;
379  } else {
380  return nullptr;
381  }
382 
383  // If the select condition is a vector, the operands of the original select's
384  // operands also must be vectors. This may not be the case for getelementptr
385  // for example.
386  if (CondTy->isVectorTy() && (!OtherOpT->getType()->isVectorTy() ||
387  !OtherOpF->getType()->isVectorTy()))
388  return nullptr;
389 
390  // If we reach here, they do have operations in common.
391  Value *NewSI = Builder.CreateSelect(Cond, OtherOpT, OtherOpF,
392  SI.getName() + ".v", &SI);
393  Value *Op0 = MatchIsOpZero ? MatchOp : NewSI;
394  Value *Op1 = MatchIsOpZero ? NewSI : MatchOp;
395  if (auto *BO = dyn_cast<BinaryOperator>(TI)) {
396  BinaryOperator *NewBO = BinaryOperator::Create(BO->getOpcode(), Op0, Op1);
397  NewBO->copyIRFlags(TI);
398  NewBO->andIRFlags(FI);
399  return NewBO;
400  }
401  if (auto *TGEP = dyn_cast<GetElementPtrInst>(TI)) {
402  auto *FGEP = cast<GetElementPtrInst>(FI);
403  Type *ElementType = TGEP->getResultElementType();
404  return TGEP->isInBounds() && FGEP->isInBounds()
405  ? GetElementPtrInst::CreateInBounds(ElementType, Op0, {Op1})
406  : GetElementPtrInst::Create(ElementType, Op0, {Op1});
407  }
408  llvm_unreachable("Expected BinaryOperator or GEP");
409  return nullptr;
410 }
411 
412 static bool isSelect01(const APInt &C1I, const APInt &C2I) {
413  if (!C1I.isNullValue() && !C2I.isNullValue()) // One side must be zero.
414  return false;
415  return C1I.isOneValue() || C1I.isAllOnesValue() ||
416  C2I.isOneValue() || C2I.isAllOnesValue();
417 }
418 
419 /// Try to fold the select into one of the operands to allow further
420 /// optimization.
421 Instruction *InstCombiner::foldSelectIntoOp(SelectInst &SI, Value *TrueVal,
422  Value *FalseVal) {
423  // See the comment above GetSelectFoldableOperands for a description of the
424  // transformation we are doing here.
425  if (auto *TVI = dyn_cast<BinaryOperator>(TrueVal)) {
426  if (TVI->hasOneUse() && !isa<Constant>(FalseVal)) {
427  if (unsigned SFO = getSelectFoldableOperands(TVI)) {
428  unsigned OpToFold = 0;
429  if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
430  OpToFold = 1;
431  } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
432  OpToFold = 2;
433  }
434 
435  if (OpToFold) {
437  Value *OOp = TVI->getOperand(2-OpToFold);
438  // Avoid creating select between 2 constants unless it's selecting
439  // between 0, 1 and -1.
440  const APInt *OOpC;
441  bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
442  if (!isa<Constant>(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) {
443  Value *C = ConstantInt::get(OOp->getType(), CI);
444  Value *NewSel = Builder.CreateSelect(SI.getCondition(), OOp, C);
445  NewSel->takeName(TVI);
446  BinaryOperator *BO = BinaryOperator::Create(TVI->getOpcode(),
447  FalseVal, NewSel);
448  BO->copyIRFlags(TVI);
449  return BO;
450  }
451  }
452  }
453  }
454  }
455 
456  if (auto *FVI = dyn_cast<BinaryOperator>(FalseVal)) {
457  if (FVI->hasOneUse() && !isa<Constant>(TrueVal)) {
458  if (unsigned SFO = getSelectFoldableOperands(FVI)) {
459  unsigned OpToFold = 0;
460  if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
461  OpToFold = 1;
462  } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
463  OpToFold = 2;
464  }
465 
466  if (OpToFold) {
468  Value *OOp = FVI->getOperand(2-OpToFold);
469  // Avoid creating select between 2 constants unless it's selecting
470  // between 0, 1 and -1.
471  const APInt *OOpC;
472  bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
473  if (!isa<Constant>(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) {
474  Value *C = ConstantInt::get(OOp->getType(), CI);
475  Value *NewSel = Builder.CreateSelect(SI.getCondition(), C, OOp);
476  NewSel->takeName(FVI);
477  BinaryOperator *BO = BinaryOperator::Create(FVI->getOpcode(),
478  TrueVal, NewSel);
479  BO->copyIRFlags(FVI);
480  return BO;
481  }
482  }
483  }
484  }
485  }
486 
487  return nullptr;
488 }
489 
490 /// We want to turn:
491 /// (select (icmp eq (and X, Y), 0), (and (lshr X, Z), 1), 1)
492 /// into:
493 /// zext (icmp ne i32 (and X, (or Y, (shl 1, Z))), 0)
494 /// Note:
495 /// Z may be 0 if lshr is missing.
496 /// Worst-case scenario is that we will replace 5 instructions with 5 different
497 /// instructions, but we got rid of select.
498 static Instruction *foldSelectICmpAndAnd(Type *SelType, const ICmpInst *Cmp,
499  Value *TVal, Value *FVal,
501  if (!(Cmp->hasOneUse() && Cmp->getOperand(0)->hasOneUse() &&
502  Cmp->getPredicate() == ICmpInst::ICMP_EQ &&
503  match(Cmp->getOperand(1), m_Zero()) && match(FVal, m_One())))
504  return nullptr;
505 
506  // The TrueVal has general form of: and %B, 1
507  Value *B;
508  if (!match(TVal, m_OneUse(m_And(m_Value(B), m_One()))))
509  return nullptr;
510 
511  // Where %B may be optionally shifted: lshr %X, %Z.
512  Value *X, *Z;
513  const bool HasShift = match(B, m_OneUse(m_LShr(m_Value(X), m_Value(Z))));
514  if (!HasShift)
515  X = B;
516 
517  Value *Y;
518  if (!match(Cmp->getOperand(0), m_c_And(m_Specific(X), m_Value(Y))))
519  return nullptr;
520 
521  // ((X & Y) == 0) ? ((X >> Z) & 1) : 1 --> (X & (Y | (1 << Z))) != 0
522  // ((X & Y) == 0) ? (X & 1) : 1 --> (X & (Y | 1)) != 0
523  Constant *One = ConstantInt::get(SelType, 1);
524  Value *MaskB = HasShift ? Builder.CreateShl(One, Z) : One;
525  Value *FullMask = Builder.CreateOr(Y, MaskB);
526  Value *MaskedX = Builder.CreateAnd(X, FullMask);
527  Value *ICmpNeZero = Builder.CreateIsNotNull(MaskedX);
528  return new ZExtInst(ICmpNeZero, SelType);
529 }
530 
531 /// We want to turn:
532 /// (select (icmp sgt x, C), lshr (X, Y), ashr (X, Y)); iff C s>= -1
533 /// (select (icmp slt x, C), ashr (X, Y), lshr (X, Y)); iff C s>= 0
534 /// into:
535 /// ashr (X, Y)
536 static Value *foldSelectICmpLshrAshr(const ICmpInst *IC, Value *TrueVal,
537  Value *FalseVal,
539  ICmpInst::Predicate Pred = IC->getPredicate();
540  Value *CmpLHS = IC->getOperand(0);
541  Value *CmpRHS = IC->getOperand(1);
542  if (!CmpRHS->getType()->isIntOrIntVectorTy())
543  return nullptr;
544 
545  Value *X, *Y;
546  unsigned Bitwidth = CmpRHS->getType()->getScalarSizeInBits();
547  if ((Pred != ICmpInst::ICMP_SGT ||
548  !match(CmpRHS,
549  m_SpecificInt_ICMP(ICmpInst::ICMP_SGE, APInt(Bitwidth, -1)))) &&
550  (Pred != ICmpInst::ICMP_SLT ||
551  !match(CmpRHS,
553  return nullptr;
554 
555  // Canonicalize so that ashr is in FalseVal.
556  if (Pred == ICmpInst::ICMP_SLT)
557  std::swap(TrueVal, FalseVal);
558 
559  if (match(TrueVal, m_LShr(m_Value(X), m_Value(Y))) &&
560  match(FalseVal, m_AShr(m_Specific(X), m_Specific(Y))) &&
561  match(CmpLHS, m_Specific(X))) {
562  const auto *Ashr = cast<Instruction>(FalseVal);
563  // if lshr is not exact and ashr is, this new ashr must not be exact.
564  bool IsExact = Ashr->isExact() && cast<Instruction>(TrueVal)->isExact();
565  return Builder.CreateAShr(X, Y, IC->getName(), IsExact);
566  }
567 
568  return nullptr;
569 }
570 
571 /// We want to turn:
572 /// (select (icmp eq (and X, C1), 0), Y, (or Y, C2))
573 /// into:
574 /// (or (shl (and X, C1), C3), Y)
575 /// iff:
576 /// C1 and C2 are both powers of 2
577 /// where:
578 /// C3 = Log(C2) - Log(C1)
579 ///
580 /// This transform handles cases where:
581 /// 1. The icmp predicate is inverted
582 /// 2. The select operands are reversed
583 /// 3. The magnitude of C2 and C1 are flipped
584 static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal,
585  Value *FalseVal,
587  // Only handle integer compares. Also, if this is a vector select, we need a
588  // vector compare.
589  if (!TrueVal->getType()->isIntOrIntVectorTy() ||
590  TrueVal->getType()->isVectorTy() != IC->getType()->isVectorTy())
591  return nullptr;
592 
593  Value *CmpLHS = IC->getOperand(0);
594  Value *CmpRHS = IC->getOperand(1);
595 
596  Value *V;
597  unsigned C1Log;
598  bool IsEqualZero;
599  bool NeedAnd = false;
600  if (IC->isEquality()) {
601  if (!match(CmpRHS, m_Zero()))
602  return nullptr;
603 
604  const APInt *C1;
605  if (!match(CmpLHS, m_And(m_Value(), m_Power2(C1))))
606  return nullptr;
607 
608  V = CmpLHS;
609  C1Log = C1->logBase2();
610  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ;
611  } else if (IC->getPredicate() == ICmpInst::ICMP_SLT ||
612  IC->getPredicate() == ICmpInst::ICMP_SGT) {
613  // We also need to recognize (icmp slt (trunc (X)), 0) and
614  // (icmp sgt (trunc (X)), -1).
615  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_SGT;
616  if ((IsEqualZero && !match(CmpRHS, m_AllOnes())) ||
617  (!IsEqualZero && !match(CmpRHS, m_Zero())))
618  return nullptr;
619 
620  if (!match(CmpLHS, m_OneUse(m_Trunc(m_Value(V)))))
621  return nullptr;
622 
623  C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1;
624  NeedAnd = true;
625  } else {
626  return nullptr;
627  }
628 
629  const APInt *C2;
630  bool OrOnTrueVal = false;
631  bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)));
632  if (!OrOnFalseVal)
633  OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2)));
634 
635  if (!OrOnFalseVal && !OrOnTrueVal)
636  return nullptr;
637 
638  Value *Y = OrOnFalseVal ? TrueVal : FalseVal;
639 
640  unsigned C2Log = C2->logBase2();
641 
642  bool NeedXor = (!IsEqualZero && OrOnFalseVal) || (IsEqualZero && OrOnTrueVal);
643  bool NeedShift = C1Log != C2Log;
644  bool NeedZExtTrunc = Y->getType()->getScalarSizeInBits() !=
646 
647  // Make sure we don't create more instructions than we save.
648  Value *Or = OrOnFalseVal ? FalseVal : TrueVal;
649  if ((NeedShift + NeedXor + NeedZExtTrunc) >
650  (IC->hasOneUse() + Or->hasOneUse()))
651  return nullptr;
652 
653  if (NeedAnd) {
654  // Insert the AND instruction on the input to the truncate.
656  V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), C1));
657  }
658 
659  if (C2Log > C1Log) {
660  V = Builder.CreateZExtOrTrunc(V, Y->getType());
661  V = Builder.CreateShl(V, C2Log - C1Log);
662  } else if (C1Log > C2Log) {
663  V = Builder.CreateLShr(V, C1Log - C2Log);
664  V = Builder.CreateZExtOrTrunc(V, Y->getType());
665  } else
666  V = Builder.CreateZExtOrTrunc(V, Y->getType());
667 
668  if (NeedXor)
669  V = Builder.CreateXor(V, *C2);
670 
671  return Builder.CreateOr(V, Y);
672 }
673 
674 /// Canonicalize a set or clear of a masked set of constant bits to
675 /// select-of-constants form.
678  Value *Cond = Sel.getCondition();
679  Value *T = Sel.getTrueValue();
680  Value *F = Sel.getFalseValue();
681  Type *Ty = Sel.getType();
682  Value *X;
683  const APInt *NotC, *C;
684 
685  // Cond ? (X & ~C) : (X | C) --> (X & ~C) | (Cond ? 0 : C)
686  if (match(T, m_And(m_Value(X), m_APInt(NotC))) &&
687  match(F, m_OneUse(m_Or(m_Specific(X), m_APInt(C)))) && *NotC == ~(*C)) {
689  Constant *OrC = ConstantInt::get(Ty, *C);
690  Value *NewSel = Builder.CreateSelect(Cond, Zero, OrC, "masksel", &Sel);
691  return BinaryOperator::CreateOr(T, NewSel);
692  }
693 
694  // Cond ? (X | C) : (X & ~C) --> (X & ~C) | (Cond ? C : 0)
695  if (match(F, m_And(m_Value(X), m_APInt(NotC))) &&
696  match(T, m_OneUse(m_Or(m_Specific(X), m_APInt(C)))) && *NotC == ~(*C)) {
698  Constant *OrC = ConstantInt::get(Ty, *C);
699  Value *NewSel = Builder.CreateSelect(Cond, OrC, Zero, "masksel", &Sel);
700  return BinaryOperator::CreateOr(F, NewSel);
701  }
702 
703  return nullptr;
704 }
705 
706 /// Transform patterns such as (a > b) ? a - b : 0 into usub.sat(a, b).
707 /// There are 8 commuted/swapped variants of this pattern.
708 /// TODO: Also support a - UMIN(a,b) patterns.
710  const Value *TrueVal,
711  const Value *FalseVal,
713  ICmpInst::Predicate Pred = ICI->getPredicate();
714  if (!ICmpInst::isUnsigned(Pred))
715  return nullptr;
716 
717  // (b > a) ? 0 : a - b -> (b <= a) ? a - b : 0
718  if (match(TrueVal, m_Zero())) {
719  Pred = ICmpInst::getInversePredicate(Pred);
720  std::swap(TrueVal, FalseVal);
721  }
722  if (!match(FalseVal, m_Zero()))
723  return nullptr;
724 
725  Value *A = ICI->getOperand(0);
726  Value *B = ICI->getOperand(1);
727  if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_ULT) {
728  // (b < a) ? a - b : 0 -> (a > b) ? a - b : 0
729  std::swap(A, B);
730  Pred = ICmpInst::getSwappedPredicate(Pred);
731  }
732 
733  assert((Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_UGT) &&
734  "Unexpected isUnsigned predicate!");
735 
736  // Ensure the sub is of the form:
737  // (a > b) ? a - b : 0 -> usub.sat(a, b)
738  // (a > b) ? b - a : 0 -> -usub.sat(a, b)
739  // Checking for both a-b and a+(-b) as a constant.
740  bool IsNegative = false;
741  const APInt *C;
742  if (match(TrueVal, m_Sub(m_Specific(B), m_Specific(A))) ||
743  (match(A, m_APInt(C)) &&
744  match(TrueVal, m_Add(m_Specific(B), m_SpecificInt(-*C)))))
745  IsNegative = true;
746  else if (!match(TrueVal, m_Sub(m_Specific(A), m_Specific(B))) &&
747  !(match(B, m_APInt(C)) &&
748  match(TrueVal, m_Add(m_Specific(A), m_SpecificInt(-*C)))))
749  return nullptr;
750 
751  // If we are adding a negate and the sub and icmp are used anywhere else, we
752  // would end up with more instructions.
753  if (IsNegative && !TrueVal->hasOneUse() && !ICI->hasOneUse())
754  return nullptr;
755 
756  // (a > b) ? a - b : 0 -> usub.sat(a, b)
757  // (a > b) ? b - a : 0 -> -usub.sat(a, b)
758  Value *Result = Builder.CreateBinaryIntrinsic(Intrinsic::usub_sat, A, B);
759  if (IsNegative)
760  Result = Builder.CreateNeg(Result);
761  return Result;
762 }
763 
764 static Value *canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal,
766  if (!Cmp->hasOneUse())
767  return nullptr;
768 
769  // Match unsigned saturated add with constant.
770  Value *Cmp0 = Cmp->getOperand(0);
771  Value *Cmp1 = Cmp->getOperand(1);
772  ICmpInst::Predicate Pred = Cmp->getPredicate();
773  Value *X;
774  const APInt *C, *CmpC;
775  if (Pred == ICmpInst::ICMP_ULT &&
776  match(TVal, m_Add(m_Value(X), m_APInt(C))) && X == Cmp0 &&
777  match(FVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) && *CmpC == ~*C) {
778  // (X u< ~C) ? (X + C) : -1 --> uadd.sat(X, C)
779  return Builder.CreateBinaryIntrinsic(
780  Intrinsic::uadd_sat, X, ConstantInt::get(X->getType(), *C));
781  }
782 
783  // Match unsigned saturated add of 2 variables with an unnecessary 'not'.
784  // There are 8 commuted variants.
785  // Canonicalize -1 (saturated result) to true value of the select. Just
786  // swapping the compare operands is legal, because the selected value is the
787  // same in case of equality, so we can interchange u< and u<=.
788  if (match(FVal, m_AllOnes())) {
789  std::swap(TVal, FVal);
790  std::swap(Cmp0, Cmp1);
791  }
792  if (!match(TVal, m_AllOnes()))
793  return nullptr;
794 
795  // Canonicalize predicate to 'ULT'.
796  if (Pred == ICmpInst::ICMP_UGT) {
797  Pred = ICmpInst::ICMP_ULT;
798  std::swap(Cmp0, Cmp1);
799  }
800  if (Pred != ICmpInst::ICMP_ULT)
801  return nullptr;
802 
803  // Match unsigned saturated add of 2 variables with an unnecessary 'not'.
804  Value *Y;
805  if (match(Cmp0, m_Not(m_Value(X))) &&
806  match(FVal, m_c_Add(m_Specific(X), m_Value(Y))) && Y == Cmp1) {
807  // (~X u< Y) ? -1 : (X + Y) --> uadd.sat(X, Y)
808  // (~X u< Y) ? -1 : (Y + X) --> uadd.sat(X, Y)
809  return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, X, Y);
810  }
811  // The 'not' op may be included in the sum but not the compare.
812  X = Cmp0;
813  Y = Cmp1;
814  if (match(FVal, m_c_Add(m_Not(m_Specific(X)), m_Specific(Y)))) {
815  // (X u< Y) ? -1 : (~X + Y) --> uadd.sat(~X, Y)
816  // (X u< Y) ? -1 : (Y + ~X) --> uadd.sat(Y, ~X)
817  BinaryOperator *BO = cast<BinaryOperator>(FVal);
818  return Builder.CreateBinaryIntrinsic(
819  Intrinsic::uadd_sat, BO->getOperand(0), BO->getOperand(1));
820  }
821  // The overflow may be detected via the add wrapping round.
822  if (match(Cmp0, m_c_Add(m_Specific(Cmp1), m_Value(Y))) &&
823  match(FVal, m_c_Add(m_Specific(Cmp1), m_Specific(Y)))) {
824  // ((X + Y) u< X) ? -1 : (X + Y) --> uadd.sat(X, Y)
825  // ((X + Y) u< Y) ? -1 : (X + Y) --> uadd.sat(X, Y)
826  return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, Cmp1, Y);
827  }
828 
829  return nullptr;
830 }
831 
832 /// Fold the following code sequence:
833 /// \code
834 /// int a = ctlz(x & -x);
835 // x ? 31 - a : a;
836 /// \code
837 ///
838 /// into:
839 /// cttz(x)
840 static Instruction *foldSelectCtlzToCttz(ICmpInst *ICI, Value *TrueVal,
841  Value *FalseVal,
843  unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits();
844  if (!ICI->isEquality() || !match(ICI->getOperand(1), m_Zero()))
845  return nullptr;
846 
847  if (ICI->getPredicate() == ICmpInst::ICMP_NE)
848  std::swap(TrueVal, FalseVal);
849 
850  if (!match(FalseVal,
851  m_Xor(m_Deferred(TrueVal), m_SpecificInt(BitWidth - 1))))
852  return nullptr;
853 
854  if (!match(TrueVal, m_Intrinsic<Intrinsic::ctlz>()))
855  return nullptr;
856 
857  Value *X = ICI->getOperand(0);
858  auto *II = cast<IntrinsicInst>(TrueVal);
859  if (!match(II->getOperand(0), m_c_And(m_Specific(X), m_Neg(m_Specific(X)))))
860  return nullptr;
861 
862  Function *F = Intrinsic::getDeclaration(II->getModule(), Intrinsic::cttz,
863  II->getType());
864  return CallInst::Create(F, {X, II->getArgOperand(1)});
865 }
866 
867 /// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single
868 /// call to cttz/ctlz with flag 'is_zero_undef' cleared.
869 ///
870 /// For example, we can fold the following code sequence:
871 /// \code
872 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
873 /// %1 = icmp ne i32 %x, 0
874 /// %2 = select i1 %1, i32 %0, i32 32
875 /// \code
876 ///
877 /// into:
878 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
879 static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
880  InstCombiner::BuilderTy &Builder) {
881  ICmpInst::Predicate Pred = ICI->getPredicate();
882  Value *CmpLHS = ICI->getOperand(0);
883  Value *CmpRHS = ICI->getOperand(1);
884 
885  // Check if the condition value compares a value for equality against zero.
886  if (!ICI->isEquality() || !match(CmpRHS, m_Zero()))
887  return nullptr;
888 
889  Value *SelectArg = FalseVal;
890  Value *ValueOnZero = TrueVal;
891  if (Pred == ICmpInst::ICMP_NE)
892  std::swap(SelectArg, ValueOnZero);
893 
894  // Skip zero extend/truncate.
895  Value *Count = nullptr;
896  if (!match(SelectArg, m_ZExt(m_Value(Count))) &&
897  !match(SelectArg, m_Trunc(m_Value(Count))))
898  Count = SelectArg;
899 
900  // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
901  // input to the cttz/ctlz is used as LHS for the compare instruction.
902  if (!match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) &&
903  !match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS))))
904  return nullptr;
905 
906  IntrinsicInst *II = cast<IntrinsicInst>(Count);
907 
908  // Check if the value propagated on zero is a constant number equal to the
909  // sizeof in bits of 'Count'.
910  unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits();
911  if (match(ValueOnZero, m_SpecificInt(SizeOfInBits))) {
912  // Explicitly clear the 'undef_on_zero' flag. It's always valid to go from
913  // true to false on this flag, so we can replace it for all users.
915  return SelectArg;
916  }
917 
918  // The ValueOnZero is not the bitwidth. But if the cttz/ctlz (and optional
919  // zext/trunc) have one use (ending at the select), the cttz/ctlz result will
920  // not be used if the input is zero. Relax to 'undef_on_zero' for that case.
921  if (II->hasOneUse() && SelectArg->hasOneUse() &&
922  !match(II->getArgOperand(1), m_One()))
924 
925  return nullptr;
926 }
927 
928 /// Return true if we find and adjust an icmp+select pattern where the compare
929 /// is with a constant that can be incremented or decremented to match the
930 /// minimum or maximum idiom.
931 static bool adjustMinMax(SelectInst &Sel, ICmpInst &Cmp) {
932  ICmpInst::Predicate Pred = Cmp.getPredicate();
933  Value *CmpLHS = Cmp.getOperand(0);
934  Value *CmpRHS = Cmp.getOperand(1);
935  Value *TrueVal = Sel.getTrueValue();
936  Value *FalseVal = Sel.getFalseValue();
937 
938  // We may move or edit the compare, so make sure the select is the only user.
939  const APInt *CmpC;
940  if (!Cmp.hasOneUse() || !match(CmpRHS, m_APInt(CmpC)))
941  return false;
942 
943  // These transforms only work for selects of integers or vector selects of
944  // integer vectors.
945  Type *SelTy = Sel.getType();
946  auto *SelEltTy = dyn_cast<IntegerType>(SelTy->getScalarType());
947  if (!SelEltTy || SelTy->isVectorTy() != Cmp.getType()->isVectorTy())
948  return false;
949 
950  Constant *AdjustedRHS;
951  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT)
952  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC + 1);
953  else if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT)
954  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC - 1);
955  else
956  return false;
957 
958  // X > C ? X : C+1 --> X < C+1 ? C+1 : X
959  // X < C ? X : C-1 --> X > C-1 ? C-1 : X
960  if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
961  (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
962  ; // Nothing to do here. Values match without any sign/zero extension.
963  }
964  // Types do not match. Instead of calculating this with mixed types, promote
965  // all to the larger type. This enables scalar evolution to analyze this
966  // expression.
967  else if (CmpRHS->getType()->getScalarSizeInBits() < SelEltTy->getBitWidth()) {
968  Constant *SextRHS = ConstantExpr::getSExt(AdjustedRHS, SelTy);
969 
970  // X = sext x; x >s c ? X : C+1 --> X = sext x; X <s C+1 ? C+1 : X
971  // X = sext x; x <s c ? X : C-1 --> X = sext x; X >s C-1 ? C-1 : X
972  // X = sext x; x >u c ? X : C+1 --> X = sext x; X <u C+1 ? C+1 : X
973  // X = sext x; x <u c ? X : C-1 --> X = sext x; X >u C-1 ? C-1 : X
974  if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) && SextRHS == FalseVal) {
975  CmpLHS = TrueVal;
976  AdjustedRHS = SextRHS;
977  } else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) &&
978  SextRHS == TrueVal) {
979  CmpLHS = FalseVal;
980  AdjustedRHS = SextRHS;
981  } else if (Cmp.isUnsigned()) {
982  Constant *ZextRHS = ConstantExpr::getZExt(AdjustedRHS, SelTy);
983  // X = zext x; x >u c ? X : C+1 --> X = zext x; X <u C+1 ? C+1 : X
984  // X = zext x; x <u c ? X : C-1 --> X = zext x; X >u C-1 ? C-1 : X
985  // zext + signed compare cannot be changed:
986  // 0xff <s 0x00, but 0x00ff >s 0x0000
987  if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) && ZextRHS == FalseVal) {
988  CmpLHS = TrueVal;
989  AdjustedRHS = ZextRHS;
990  } else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) &&
991  ZextRHS == TrueVal) {
992  CmpLHS = FalseVal;
993  AdjustedRHS = ZextRHS;
994  } else {
995  return false;
996  }
997  } else {
998  return false;
999  }
1000  } else {
1001  return false;
1002  }
1003 
1004  Pred = ICmpInst::getSwappedPredicate(Pred);
1005  CmpRHS = AdjustedRHS;
1006  std::swap(FalseVal, TrueVal);
1007  Cmp.setPredicate(Pred);
1008  Cmp.setOperand(0, CmpLHS);
1009  Cmp.setOperand(1, CmpRHS);
1010  Sel.setOperand(1, TrueVal);
1011  Sel.setOperand(2, FalseVal);
1012  Sel.swapProfMetadata();
1013 
1014  // Move the compare instruction right before the select instruction. Otherwise
1015  // the sext/zext value may be defined after the compare instruction uses it.
1016  Cmp.moveBefore(&Sel);
1017 
1018  return true;
1019 }
1020 
1021 /// If this is an integer min/max (icmp + select) with a constant operand,
1022 /// create the canonical icmp for the min/max operation and canonicalize the
1023 /// constant to the 'false' operand of the select:
1024 /// select (icmp Pred X, C1), C2, X --> select (icmp Pred' X, C2), X, C2
1025 /// Note: if C1 != C2, this will change the icmp constant to the existing
1026 /// constant operand of the select.
1027 static Instruction *
1028 canonicalizeMinMaxWithConstant(SelectInst &Sel, ICmpInst &Cmp,
1029  InstCombiner &IC) {
1030  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
1031  return nullptr;
1032 
1033  // Canonicalize the compare predicate based on whether we have min or max.
1034  Value *LHS, *RHS;
1035  SelectPatternResult SPR = matchSelectPattern(&Sel, LHS, RHS);
1037  return nullptr;
1038 
1039  // Is this already canonical?
1040  ICmpInst::Predicate CanonicalPred = getMinMaxPred(SPR.Flavor);
1041  if (Cmp.getOperand(0) == LHS && Cmp.getOperand(1) == RHS &&
1042  Cmp.getPredicate() == CanonicalPred)
1043  return nullptr;
1044 
1045  // Bail out on unsimplified X-0 operand (due to some worklist management bug),
1046  // as this may cause an infinite combine loop. Let the sub be folded first.
1047  if (match(LHS, m_Sub(m_Value(), m_Zero())) ||
1048  match(RHS, m_Sub(m_Value(), m_Zero())))
1049  return nullptr;
1050 
1051  // Create the canonical compare and plug it into the select.
1052  IC.replaceOperand(Sel, 0, IC.Builder.CreateICmp(CanonicalPred, LHS, RHS));
1053 
1054  // If the select operands did not change, we're done.
1055  if (Sel.getTrueValue() == LHS && Sel.getFalseValue() == RHS)
1056  return &Sel;
1057 
1058  // If we are swapping the select operands, swap the metadata too.
1059  assert(Sel.getTrueValue() == RHS && Sel.getFalseValue() == LHS &&
1060  "Unexpected results from matchSelectPattern");
1061  Sel.swapValues();
1062  Sel.swapProfMetadata();
1063  return &Sel;
1064 }
1065 
1066 /// There are many select variants for each of ABS/NABS.
1067 /// In matchSelectPattern(), there are different compare constants, compare
1068 /// predicates/operands and select operands.
1069 /// In isKnownNegation(), there are different formats of negated operands.
1070 /// Canonicalize all these variants to 1 pattern.
1071 /// This makes CSE more likely.
1072 static Instruction *canonicalizeAbsNabs(SelectInst &Sel, ICmpInst &Cmp,
1073  InstCombiner &IC) {
1074  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
1075  return nullptr;
1076 
1077  // Choose a sign-bit check for the compare (likely simpler for codegen).
1078  // ABS: (X <s 0) ? -X : X
1079  // NABS: (X <s 0) ? X : -X
1080  Value *LHS, *RHS;
1081  SelectPatternFlavor SPF = matchSelectPattern(&Sel, LHS, RHS).Flavor;
1082  if (SPF != SelectPatternFlavor::SPF_ABS &&
1084  return nullptr;
1085 
1086  Value *TVal = Sel.getTrueValue();
1087  Value *FVal = Sel.getFalseValue();
1088  assert(isKnownNegation(TVal, FVal) &&
1089  "Unexpected result from matchSelectPattern");
1090 
1091  // The compare may use the negated abs()/nabs() operand, or it may use
1092  // negation in non-canonical form such as: sub A, B.
1093  bool CmpUsesNegatedOp = match(Cmp.getOperand(0), m_Neg(m_Specific(TVal))) ||
1094  match(Cmp.getOperand(0), m_Neg(m_Specific(FVal)));
1095 
1096  bool CmpCanonicalized = !CmpUsesNegatedOp &&
1097  match(Cmp.getOperand(1), m_ZeroInt()) &&
1099  bool RHSCanonicalized = match(RHS, m_Neg(m_Specific(LHS)));
1100 
1101  // Is this already canonical?
1102  if (CmpCanonicalized && RHSCanonicalized)
1103  return nullptr;
1104 
1105  // If RHS is not canonical but is used by other instructions, don't
1106  // canonicalize it and potentially increase the instruction count.
1107  if (!RHSCanonicalized)
1108  if (!(RHS->hasOneUse() || (RHS->hasNUses(2) && CmpUsesNegatedOp)))
1109  return nullptr;
1110 
1111  // Create the canonical compare: icmp slt LHS 0.
1112  if (!CmpCanonicalized) {
1115  if (CmpUsesNegatedOp)
1116  Cmp.setOperand(0, LHS);
1117  }
1118 
1119  // Create the canonical RHS: RHS = sub (0, LHS).
1120  if (!RHSCanonicalized) {
1121  assert(RHS->hasOneUse() && "RHS use number is not right");
1122  RHS = IC.Builder.CreateNeg(LHS);
1123  if (TVal == LHS) {
1124  // Replace false value.
1125  IC.replaceOperand(Sel, 2, RHS);
1126  FVal = RHS;
1127  } else {
1128  // Replace true value.
1129  IC.replaceOperand(Sel, 1, RHS);
1130  TVal = RHS;
1131  }
1132  }
1133 
1134  // If the select operands do not change, we're done.
1135  if (SPF == SelectPatternFlavor::SPF_NABS) {
1136  if (TVal == LHS)
1137  return &Sel;
1138  assert(FVal == LHS && "Unexpected results from matchSelectPattern");
1139  } else {
1140  if (FVal == LHS)
1141  return &Sel;
1142  assert(TVal == LHS && "Unexpected results from matchSelectPattern");
1143  }
1144 
1145  // We are swapping the select operands, so swap the metadata too.
1146  Sel.swapValues();
1147  Sel.swapProfMetadata();
1148  return &Sel;
1149 }
1150 
1151 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *ReplaceOp,
1152  const SimplifyQuery &Q) {
1153  // If this is a binary operator, try to simplify it with the replaced op
1154  // because we know Op and ReplaceOp are equivalant.
1155  // For example: V = X + 1, Op = X, ReplaceOp = 42
1156  // Simplifies as: add(42, 1) --> 43
1157  if (auto *BO = dyn_cast<BinaryOperator>(V)) {
1158  if (BO->getOperand(0) == Op)
1159  return SimplifyBinOp(BO->getOpcode(), ReplaceOp, BO->getOperand(1), Q);
1160  if (BO->getOperand(1) == Op)
1161  return SimplifyBinOp(BO->getOpcode(), BO->getOperand(0), ReplaceOp, Q);
1162  }
1163 
1164  return nullptr;
1165 }
1166 
1167 /// If we have a select with an equality comparison, then we know the value in
1168 /// one of the arms of the select. See if substituting this value into an arm
1169 /// and simplifying the result yields the same value as the other arm.
1170 ///
1171 /// To make this transform safe, we must drop poison-generating flags
1172 /// (nsw, etc) if we simplified to a binop because the select may be guarding
1173 /// that poison from propagating. If the existing binop already had no
1174 /// poison-generating flags, then this transform can be done by instsimplify.
1175 ///
1176 /// Consider:
1177 /// %cmp = icmp eq i32 %x, 2147483647
1178 /// %add = add nsw i32 %x, 1
1179 /// %sel = select i1 %cmp, i32 -2147483648, i32 %add
1180 ///
1181 /// We can't replace %sel with %add unless we strip away the flags.
1182 /// TODO: Wrapping flags could be preserved in some cases with better analysis.
1183 static Value *foldSelectValueEquivalence(SelectInst &Sel, ICmpInst &Cmp,
1184  const SimplifyQuery &Q) {
1185  if (!Cmp.isEquality())
1186  return nullptr;
1187 
1188  // Canonicalize the pattern to ICMP_EQ by swapping the select operands.
1189  Value *TrueVal = Sel.getTrueValue(), *FalseVal = Sel.getFalseValue();
1190  if (Cmp.getPredicate() == ICmpInst::ICMP_NE)
1191  std::swap(TrueVal, FalseVal);
1192 
1193  // Try each equivalence substitution possibility.
1194  // We have an 'EQ' comparison, so the select's false value will propagate.
1195  // Example:
1196  // (X == 42) ? 43 : (X + 1) --> (X == 42) ? (X + 1) : (X + 1) --> X + 1
1197  // (X == 42) ? (X + 1) : 43 --> (X == 42) ? (42 + 1) : 43 --> 43
1198  Value *CmpLHS = Cmp.getOperand(0), *CmpRHS = Cmp.getOperand(1);
1199  if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q) == TrueVal ||
1200  simplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q) == TrueVal ||
1201  simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q) == FalseVal ||
1202  simplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q) == FalseVal) {
1203  if (auto *FalseInst = dyn_cast<Instruction>(FalseVal))
1204  FalseInst->dropPoisonGeneratingFlags();
1205  return FalseVal;
1206  }
1207  return nullptr;
1208 }
1209 
1210 // See if this is a pattern like:
1211 // %old_cmp1 = icmp slt i32 %x, C2
1212 // %old_replacement = select i1 %old_cmp1, i32 %target_low, i32 %target_high
1213 // %old_x_offseted = add i32 %x, C1
1214 // %old_cmp0 = icmp ult i32 %old_x_offseted, C0
1215 // %r = select i1 %old_cmp0, i32 %x, i32 %old_replacement
1216 // This can be rewritten as more canonical pattern:
1217 // %new_cmp1 = icmp slt i32 %x, -C1
1218 // %new_cmp2 = icmp sge i32 %x, C0-C1
1219 // %new_clamped_low = select i1 %new_cmp1, i32 %target_low, i32 %x
1220 // %r = select i1 %new_cmp2, i32 %target_high, i32 %new_clamped_low
1221 // Iff -C1 s<= C2 s<= C0-C1
1222 // Also ULT predicate can also be UGT iff C0 != -1 (+invert result)
1223 // SLT predicate can also be SGT iff C2 != INT_MAX (+invert res.)
1224 static Instruction *canonicalizeClampLike(SelectInst &Sel0, ICmpInst &Cmp0,
1225  InstCombiner::BuilderTy &Builder) {
1226  Value *X = Sel0.getTrueValue();
1227  Value *Sel1 = Sel0.getFalseValue();
1228 
1229  // First match the condition of the outermost select.
1230  // Said condition must be one-use.
1231  if (!Cmp0.hasOneUse())
1232  return nullptr;
1233  Value *Cmp00 = Cmp0.getOperand(0);
1234  Constant *C0;
1235  if (!match(Cmp0.getOperand(1),
1237  return nullptr;
1238  // Canonicalize Cmp0 into the form we expect.
1239  // FIXME: we shouldn't care about lanes that are 'undef' in the end?
1240  switch (Cmp0.getPredicate()) {
1241  case ICmpInst::Predicate::ICMP_ULT:
1242  break; // Great!
1243  case ICmpInst::Predicate::ICMP_ULE:
1244  // We'd have to increment C0 by one, and for that it must not have all-ones
1245  // element, but then it would have been canonicalized to 'ult' before
1246  // we get here. So we can't do anything useful with 'ule'.
1247  return nullptr;
1248  case ICmpInst::Predicate::ICMP_UGT:
1249  // We want to canonicalize it to 'ult', so we'll need to increment C0,
1250  // which again means it must not have any all-ones elements.
1251  if (!match(C0,
1252  m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_NE,
1254  C0->getType()->getScalarSizeInBits()))))
1255  return nullptr; // Can't do, have all-ones element[s].
1256  C0 = AddOne(C0);
1257  std::swap(X, Sel1);
1258  break;
1259  case ICmpInst::Predicate::ICMP_UGE:
1260  // The only way we'd get this predicate if this `icmp` has extra uses,
1261  // but then we won't be able to do this fold.
1262  return nullptr;
1263  default:
1264  return nullptr; // Unknown predicate.
1265  }
1266 
1267  // Now that we've canonicalized the ICmp, we know the X we expect;
1268  // the select in other hand should be one-use.
1269  if (!Sel1->hasOneUse())
1270  return nullptr;
1271 
1272  // We now can finish matching the condition of the outermost select:
1273  // it should either be the X itself, or an addition of some constant to X.
1274  Constant *C1;
1275  if (Cmp00 == X)
1276  C1 = ConstantInt::getNullValue(Sel0.getType());
1277  else if (!match(Cmp00,
1278  m_Add(m_Specific(X),
1280  return nullptr;
1281 
1282  Value *Cmp1;
1283  ICmpInst::Predicate Pred1;
1284  Constant *C2;
1285  Value *ReplacementLow, *ReplacementHigh;
1286  if (!match(Sel1, m_Select(m_Value(Cmp1), m_Value(ReplacementLow),
1287  m_Value(ReplacementHigh))) ||
1288  !match(Cmp1,
1289  m_ICmp(Pred1, m_Specific(X),
1291  return nullptr;
1292 
1293  if (!Cmp1->hasOneUse() && (Cmp00 == X || !Cmp00->hasOneUse()))
1294  return nullptr; // Not enough one-use instructions for the fold.
1295  // FIXME: this restriction could be relaxed if Cmp1 can be reused as one of
1296  // two comparisons we'll need to build.
1297 
1298  // Canonicalize Cmp1 into the form we expect.
1299  // FIXME: we shouldn't care about lanes that are 'undef' in the end?
1300  switch (Pred1) {
1301  case ICmpInst::Predicate::ICMP_SLT:
1302  break;
1303  case ICmpInst::Predicate::ICMP_SLE:
1304  // We'd have to increment C2 by one, and for that it must not have signed
1305  // max element, but then it would have been canonicalized to 'slt' before
1306  // we get here. So we can't do anything useful with 'sle'.
1307  return nullptr;
1308  case ICmpInst::Predicate::ICMP_SGT:
1309  // We want to canonicalize it to 'slt', so we'll need to increment C2,
1310  // which again means it must not have any signed max elements.
1311  if (!match(C2,
1312  m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_NE,
1314  C2->getType()->getScalarSizeInBits()))))
1315  return nullptr; // Can't do, have signed max element[s].
1316  C2 = AddOne(C2);
1318  case ICmpInst::Predicate::ICMP_SGE:
1319  // Also non-canonical, but here we don't need to change C2,
1320  // so we don't have any restrictions on C2, so we can just handle it.
1321  std::swap(ReplacementLow, ReplacementHigh);
1322  break;
1323  default:
1324  return nullptr; // Unknown predicate.
1325  }
1326 
1327  // The thresholds of this clamp-like pattern.
1328  auto *ThresholdLowIncl = ConstantExpr::getNeg(C1);
1329  auto *ThresholdHighExcl = ConstantExpr::getSub(C0, C1);
1330 
1331  // The fold has a precondition 1: C2 s>= ThresholdLow
1332  auto *Precond1 = ConstantExpr::getICmp(ICmpInst::Predicate::ICMP_SGE, C2,
1333  ThresholdLowIncl);
1334  if (!match(Precond1, m_One()))
1335  return nullptr;
1336  // The fold has a precondition 2: C2 s<= ThresholdHigh
1337  auto *Precond2 = ConstantExpr::getICmp(ICmpInst::Predicate::ICMP_SLE, C2,
1338  ThresholdHighExcl);
1339  if (!match(Precond2, m_One()))
1340  return nullptr;
1341 
1342  // All good, finally emit the new pattern.
1343  Value *ShouldReplaceLow = Builder.CreateICmpSLT(X, ThresholdLowIncl);
1344  Value *ShouldReplaceHigh = Builder.CreateICmpSGE(X, ThresholdHighExcl);
1345  Value *MaybeReplacedLow =
1346  Builder.CreateSelect(ShouldReplaceLow, ReplacementLow, X);
1347  Instruction *MaybeReplacedHigh =
1348  SelectInst::Create(ShouldReplaceHigh, ReplacementHigh, MaybeReplacedLow);
1349 
1350  return MaybeReplacedHigh;
1351 }
1352 
1353 // If we have
1354 // %cmp = icmp [canonical predicate] i32 %x, C0
1355 // %r = select i1 %cmp, i32 %y, i32 C1
1356 // Where C0 != C1 and %x may be different from %y, see if the constant that we
1357 // will have if we flip the strictness of the predicate (i.e. without changing
1358 // the result) is identical to the C1 in select. If it matches we can change
1359 // original comparison to one with swapped predicate, reuse the constant,
1360 // and swap the hands of select.
1361 static Instruction *
1362 tryToReuseConstantFromSelectInComparison(SelectInst &Sel, ICmpInst &Cmp,
1363  InstCombiner &IC) {
1364  ICmpInst::Predicate Pred;
1365  Value *X;
1366  Constant *C0;
1367  if (!match(&Cmp, m_OneUse(m_ICmp(
1368  Pred, m_Value(X),
1370  return nullptr;
1371 
1372  // If comparison predicate is non-relational, we won't be able to do anything.
1373  if (ICmpInst::isEquality(Pred))
1374  return nullptr;
1375 
1376  // If comparison predicate is non-canonical, then we certainly won't be able
1377  // to make it canonical; canonicalizeCmpWithConstant() already tried.
1378  if (!isCanonicalPredicate(Pred))
1379  return nullptr;
1380 
1381  // If the [input] type of comparison and select type are different, lets abort
1382  // for now. We could try to compare constants with trunc/[zs]ext though.
1383  if (C0->getType() != Sel.getType())
1384  return nullptr;
1385 
1386  // FIXME: are there any magic icmp predicate+constant pairs we must not touch?
1387 
1388  Value *SelVal0, *SelVal1; // We do not care which one is from where.
1389  match(&Sel, m_Select(m_Value(), m_Value(SelVal0), m_Value(SelVal1)));
1390  // At least one of these values we are selecting between must be a constant
1391  // else we'll never succeed.
1392  if (!match(SelVal0, m_AnyIntegralConstant()) &&
1393  !match(SelVal1, m_AnyIntegralConstant()))
1394  return nullptr;
1395 
1396  // Does this constant C match any of the `select` values?
1397  auto MatchesSelectValue = [SelVal0, SelVal1](Constant *C) {
1398  return C->isElementWiseEqual(SelVal0) || C->isElementWiseEqual(SelVal1);
1399  };
1400 
1401  // If C0 *already* matches true/false value of select, we are done.
1402  if (MatchesSelectValue(C0))
1403  return nullptr;
1404 
1405  // Check the constant we'd have with flipped-strictness predicate.
1406  auto FlippedStrictness = getFlippedStrictnessPredicateAndConstant(Pred, C0);
1407  if (!FlippedStrictness)
1408  return nullptr;
1409 
1410  // If said constant doesn't match either, then there is no hope,
1411  if (!MatchesSelectValue(FlippedStrictness->second))
1412  return nullptr;
1413 
1414  // It matched! Lets insert the new comparison just before select.
1415  InstCombiner::BuilderTy::InsertPointGuard Guard(IC.Builder);
1416  IC.Builder.SetInsertPoint(&Sel);
1417 
1418  Pred = ICmpInst::getSwappedPredicate(Pred); // Yes, swapped.
1419  Value *NewCmp = IC.Builder.CreateICmp(Pred, X, FlippedStrictness->second,
1420  Cmp.getName() + ".inv");
1421  IC.replaceOperand(Sel, 0, NewCmp);
1422  Sel.swapValues();
1423  Sel.swapProfMetadata();
1424 
1425  return &Sel;
1426 }
1427 
1428 /// Visit a SelectInst that has an ICmpInst as its first operand.
1429 Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI,
1430  ICmpInst *ICI) {
1431  if (Value *V = foldSelectValueEquivalence(SI, *ICI, SQ))
1432  return replaceInstUsesWith(SI, V);
1433 
1434  if (Instruction *NewSel = canonicalizeMinMaxWithConstant(SI, *ICI, *this))
1435  return NewSel;
1436 
1437  if (Instruction *NewAbs = canonicalizeAbsNabs(SI, *ICI, *this))
1438  return NewAbs;
1439 
1440  if (Instruction *NewAbs = canonicalizeClampLike(SI, *ICI, Builder))
1441  return NewAbs;
1442 
1443  if (Instruction *NewSel =
1444  tryToReuseConstantFromSelectInComparison(SI, *ICI, *this))
1445  return NewSel;
1446 
1447  bool Changed = adjustMinMax(SI, *ICI);
1448 
1449  if (Value *V = foldSelectICmpAnd(SI, ICI, Builder))
1450  return replaceInstUsesWith(SI, V);
1451 
1452  // NOTE: if we wanted to, this is where to detect integer MIN/MAX
1453  Value *TrueVal = SI.getTrueValue();
1454  Value *FalseVal = SI.getFalseValue();
1455  ICmpInst::Predicate Pred = ICI->getPredicate();
1456  Value *CmpLHS = ICI->getOperand(0);
1457  Value *CmpRHS = ICI->getOperand(1);
1458  if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
1459  if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
1460  // Transform (X == C) ? X : Y -> (X == C) ? C : Y
1461  SI.setOperand(1, CmpRHS);
1462  Changed = true;
1463  } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
1464  // Transform (X != C) ? Y : X -> (X != C) ? Y : C
1465  SI.setOperand(2, CmpRHS);
1466  Changed = true;
1467  }
1468  }
1469 
1470  // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring
1471  // decomposeBitTestICmp() might help.
1472  {
1473  unsigned BitWidth =
1474  DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
1475  APInt MinSignedValue = APInt::getSignedMinValue(BitWidth);
1476  Value *X;
1477  const APInt *Y, *C;
1478  bool TrueWhenUnset;
1479  bool IsBitTest = false;
1480  if (ICmpInst::isEquality(Pred) &&
1481  match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) &&
1482  match(CmpRHS, m_Zero())) {
1483  IsBitTest = true;
1484  TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
1485  } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
1486  X = CmpLHS;
1487  Y = &MinSignedValue;
1488  IsBitTest = true;
1489  TrueWhenUnset = false;
1490  } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
1491  X = CmpLHS;
1492  Y = &MinSignedValue;
1493  IsBitTest = true;
1494  TrueWhenUnset = true;
1495  }
1496  if (IsBitTest) {
1497  Value *V = nullptr;
1498  // (X & Y) == 0 ? X : X ^ Y --> X & ~Y
1499  if (TrueWhenUnset && TrueVal == X &&
1500  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1501  V = Builder.CreateAnd(X, ~(*Y));
1502  // (X & Y) != 0 ? X ^ Y : X --> X & ~Y
1503  else if (!TrueWhenUnset && FalseVal == X &&
1504  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1505  V = Builder.CreateAnd(X, ~(*Y));
1506  // (X & Y) == 0 ? X ^ Y : X --> X | Y
1507  else if (TrueWhenUnset && FalseVal == X &&
1508  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1509  V = Builder.CreateOr(X, *Y);
1510  // (X & Y) != 0 ? X : X ^ Y --> X | Y
1511  else if (!TrueWhenUnset && TrueVal == X &&
1512  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1513  V = Builder.CreateOr(X, *Y);
1514 
1515  if (V)
1516  return replaceInstUsesWith(SI, V);
1517  }
1518  }
1519 
1520  if (Instruction *V =
1521  foldSelectICmpAndAnd(SI.getType(), ICI, TrueVal, FalseVal, Builder))
1522  return V;
1523 
1524  if (Instruction *V = foldSelectCtlzToCttz(ICI, TrueVal, FalseVal, Builder))
1525  return V;
1526 
1527  if (Value *V = foldSelectICmpAndOr(ICI, TrueVal, FalseVal, Builder))
1528  return replaceInstUsesWith(SI, V);
1529 
1530  if (Value *V = foldSelectICmpLshrAshr(ICI, TrueVal, FalseVal, Builder))
1531  return replaceInstUsesWith(SI, V);
1532 
1533  if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
1534  return replaceInstUsesWith(SI, V);
1535 
1536  if (Value *V = canonicalizeSaturatedSubtract(ICI, TrueVal, FalseVal, Builder))
1537  return replaceInstUsesWith(SI, V);
1538 
1539  if (Value *V = canonicalizeSaturatedAdd(ICI, TrueVal, FalseVal, Builder))
1540  return replaceInstUsesWith(SI, V);
1541 
1542  return Changed ? &SI : nullptr;
1543 }
1544 
1545 /// SI is a select whose condition is a PHI node (but the two may be in
1546 /// different blocks). See if the true/false values (V) are live in all of the
1547 /// predecessor blocks of the PHI. For example, cases like this can't be mapped:
1548 ///
1549 /// X = phi [ C1, BB1], [C2, BB2]
1550 /// Y = add
1551 /// Z = select X, Y, 0
1552 ///
1553 /// because Y is not live in BB1/BB2.
1554 static bool canSelectOperandBeMappingIntoPredBlock(const Value *V,
1555  const SelectInst &SI) {
1556  // If the value is a non-instruction value like a constant or argument, it
1557  // can always be mapped.
1558  const Instruction *I = dyn_cast<Instruction>(V);
1559  if (!I) return true;
1560 
1561  // If V is a PHI node defined in the same block as the condition PHI, we can
1562  // map the arguments.
1563  const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
1564 
1565  if (const PHINode *VP = dyn_cast<PHINode>(I))
1566  if (VP->getParent() == CondPHI->getParent())
1567  return true;
1568 
1569  // Otherwise, if the PHI and select are defined in the same block and if V is
1570  // defined in a different block, then we can transform it.
1571  if (SI.getParent() == CondPHI->getParent() &&
1572  I->getParent() != CondPHI->getParent())
1573  return true;
1574 
1575  // Otherwise we have a 'hard' case and we can't tell without doing more
1576  // detailed dominator based analysis, punt.
1577  return false;
1578 }
1579 
1580 /// We have an SPF (e.g. a min or max) of an SPF of the form:
1581 /// SPF2(SPF1(A, B), C)
1582 Instruction *InstCombiner::foldSPFofSPF(Instruction *Inner,
1583  SelectPatternFlavor SPF1,
1584  Value *A, Value *B,
1585  Instruction &Outer,
1586  SelectPatternFlavor SPF2, Value *C) {
1587  if (Outer.getType() != Inner->getType())
1588  return nullptr;
1589 
1590  if (C == A || C == B) {
1591  // MAX(MAX(A, B), B) -> MAX(A, B)
1592  // MIN(MIN(a, b), a) -> MIN(a, b)
1593  // TODO: This could be done in instsimplify.
1594  if (SPF1 == SPF2 && SelectPatternResult::isMinOrMax(SPF1))
1595  return replaceInstUsesWith(Outer, Inner);
1596 
1597  // MAX(MIN(a, b), a) -> a
1598  // MIN(MAX(a, b), a) -> a
1599  // TODO: This could be done in instsimplify.
1600  if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
1601  (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
1602  (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
1603  (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
1604  return replaceInstUsesWith(Outer, C);
1605  }
1606 
1607  if (SPF1 == SPF2) {
1608  const APInt *CB, *CC;
1609  if (match(B, m_APInt(CB)) && match(C, m_APInt(CC))) {
1610  // MIN(MIN(A, 23), 97) -> MIN(A, 23)
1611  // MAX(MAX(A, 97), 23) -> MAX(A, 97)
1612  // TODO: This could be done in instsimplify.
1613  if ((SPF1 == SPF_UMIN && CB->ule(*CC)) ||
1614  (SPF1 == SPF_SMIN && CB->sle(*CC)) ||
1615  (SPF1 == SPF_UMAX && CB->uge(*CC)) ||
1616  (SPF1 == SPF_SMAX && CB->sge(*CC)))
1617  return replaceInstUsesWith(Outer, Inner);
1618 
1619  // MIN(MIN(A, 97), 23) -> MIN(A, 23)
1620  // MAX(MAX(A, 23), 97) -> MAX(A, 97)
1621  if ((SPF1 == SPF_UMIN && CB->ugt(*CC)) ||
1622  (SPF1 == SPF_SMIN && CB->sgt(*CC)) ||
1623  (SPF1 == SPF_UMAX && CB->ult(*CC)) ||
1624  (SPF1 == SPF_SMAX && CB->slt(*CC))) {
1625  Outer.replaceUsesOfWith(Inner, A);
1626  return &Outer;
1627  }
1628  }
1629  }
1630 
1631  // max(max(A, B), min(A, B)) --> max(A, B)
1632  // min(min(A, B), max(A, B)) --> min(A, B)
1633  // TODO: This could be done in instsimplify.
1634  if (SPF1 == SPF2 &&
1635  ((SPF1 == SPF_UMIN && match(C, m_c_UMax(m_Specific(A), m_Specific(B)))) ||
1636  (SPF1 == SPF_SMIN && match(C, m_c_SMax(m_Specific(A), m_Specific(B)))) ||
1637  (SPF1 == SPF_UMAX && match(C, m_c_UMin(m_Specific(A), m_Specific(B)))) ||
1638  (SPF1 == SPF_SMAX && match(C, m_c_SMin(m_Specific(A), m_Specific(B))))))
1639  return replaceInstUsesWith(Outer, Inner);
1640 
1641  // ABS(ABS(X)) -> ABS(X)
1642  // NABS(NABS(X)) -> NABS(X)
1643  // TODO: This could be done in instsimplify.
1644  if (SPF1 == SPF2 && (SPF1 == SPF_ABS || SPF1 == SPF_NABS)) {
1645  return replaceInstUsesWith(Outer, Inner);
1646  }
1647 
1648  // ABS(NABS(X)) -> ABS(X)
1649  // NABS(ABS(X)) -> NABS(X)
1650  if ((SPF1 == SPF_ABS && SPF2 == SPF_NABS) ||
1651  (SPF1 == SPF_NABS && SPF2 == SPF_ABS)) {
1652  SelectInst *SI = cast<SelectInst>(Inner);
1653  Value *NewSI =
1654  Builder.CreateSelect(SI->getCondition(), SI->getFalseValue(),
1655  SI->getTrueValue(), SI->getName(), SI);
1656  return replaceInstUsesWith(Outer, NewSI);
1657  }
1658 
1659  auto IsFreeOrProfitableToInvert =
1660  [&](Value *V, Value *&NotV, bool &ElidesXor) {
1661  if (match(V, m_Not(m_Value(NotV)))) {
1662  // If V has at most 2 uses then we can get rid of the xor operation
1663  // entirely.
1664  ElidesXor |= !V->hasNUsesOrMore(3);
1665  return true;
1666  }
1667 
1668  if (isFreeToInvert(V, !V->hasNUsesOrMore(3))) {
1669  NotV = nullptr;
1670  return true;
1671  }
1672 
1673  return false;
1674  };
1675 
1676  Value *NotA, *NotB, *NotC;
1677  bool ElidesXor = false;
1678 
1679  // MIN(MIN(~A, ~B), ~C) == ~MAX(MAX(A, B), C)
1680  // MIN(MAX(~A, ~B), ~C) == ~MAX(MIN(A, B), C)
1681  // MAX(MIN(~A, ~B), ~C) == ~MIN(MAX(A, B), C)
1682  // MAX(MAX(~A, ~B), ~C) == ~MIN(MIN(A, B), C)
1683  //
1684  // This transform is performance neutral if we can elide at least one xor from
1685  // the set of three operands, since we'll be tacking on an xor at the very
1686  // end.
1687  if (SelectPatternResult::isMinOrMax(SPF1) &&
1689  IsFreeOrProfitableToInvert(A, NotA, ElidesXor) &&
1690  IsFreeOrProfitableToInvert(B, NotB, ElidesXor) &&
1691  IsFreeOrProfitableToInvert(C, NotC, ElidesXor) && ElidesXor) {
1692  if (!NotA)
1693  NotA = Builder.CreateNot(A);
1694  if (!NotB)
1695  NotB = Builder.CreateNot(B);
1696  if (!NotC)
1697  NotC = Builder.CreateNot(C);
1698 
1699  Value *NewInner = createMinMax(Builder, getInverseMinMaxFlavor(SPF1), NotA,
1700  NotB);
1701  Value *NewOuter = Builder.CreateNot(
1702  createMinMax(Builder, getInverseMinMaxFlavor(SPF2), NewInner, NotC));
1703  return replaceInstUsesWith(Outer, NewOuter);
1704  }
1705 
1706  return nullptr;
1707 }
1708 
1709 /// Turn select C, (X + Y), (X - Y) --> (X + (select C, Y, (-Y))).
1710 /// This is even legal for FP.
1711 static Instruction *foldAddSubSelect(SelectInst &SI,
1712  InstCombiner::BuilderTy &Builder) {
1713  Value *CondVal = SI.getCondition();
1714  Value *TrueVal = SI.getTrueValue();
1715  Value *FalseVal = SI.getFalseValue();
1716  auto *TI = dyn_cast<Instruction>(TrueVal);
1717  auto *FI = dyn_cast<Instruction>(FalseVal);
1718  if (!TI || !FI || !TI->hasOneUse() || !FI->hasOneUse())
1719  return nullptr;
1720 
1721  Instruction *AddOp = nullptr, *SubOp = nullptr;
1722  if ((TI->getOpcode() == Instruction::Sub &&
1723  FI->getOpcode() == Instruction::Add) ||
1724  (TI->getOpcode() == Instruction::FSub &&
1725  FI->getOpcode() == Instruction::FAdd)) {
1726  AddOp = FI;
1727  SubOp = TI;
1728  } else if ((FI->getOpcode() == Instruction::Sub &&
1729  TI->getOpcode() == Instruction::Add) ||
1730  (FI->getOpcode() == Instruction::FSub &&
1731  TI->getOpcode() == Instruction::FAdd)) {
1732  AddOp = TI;
1733  SubOp = FI;
1734  }
1735 
1736  if (AddOp) {
1737  Value *OtherAddOp = nullptr;
1738  if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
1739  OtherAddOp = AddOp->getOperand(1);
1740  } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
1741  OtherAddOp = AddOp->getOperand(0);
1742  }
1743 
1744  if (OtherAddOp) {
1745  // So at this point we know we have (Y -> OtherAddOp):
1746  // select C, (add X, Y), (sub X, Z)
1747  Value *NegVal; // Compute -Z
1748  if (SI.getType()->isFPOrFPVectorTy()) {
1749  NegVal = Builder.CreateFNeg(SubOp->getOperand(1));
1750  if (Instruction *NegInst = dyn_cast<Instruction>(NegVal)) {
1751  FastMathFlags Flags = AddOp->getFastMathFlags();
1752  Flags &= SubOp->getFastMathFlags();
1753  NegInst->setFastMathFlags(Flags);
1754  }
1755  } else {
1756  NegVal = Builder.CreateNeg(SubOp->getOperand(1));
1757  }
1758 
1759  Value *NewTrueOp = OtherAddOp;
1760  Value *NewFalseOp = NegVal;
1761  if (AddOp != TI)
1762  std::swap(NewTrueOp, NewFalseOp);
1763  Value *NewSel = Builder.CreateSelect(CondVal, NewTrueOp, NewFalseOp,
1764  SI.getName() + ".p", &SI);
1765 
1766  if (SI.getType()->isFPOrFPVectorTy()) {
1767  Instruction *RI =
1768  BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel);
1769 
1770  FastMathFlags Flags = AddOp->getFastMathFlags();
1771  Flags &= SubOp->getFastMathFlags();
1772  RI->setFastMathFlags(Flags);
1773  return RI;
1774  } else
1775  return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
1776  }
1777  }
1778  return nullptr;
1779 }
1780 
1781 /// Turn X + Y overflows ? -1 : X + Y -> uadd_sat X, Y
1782 /// And X - Y overflows ? 0 : X - Y -> usub_sat X, Y
1783 /// Along with a number of patterns similar to:
1784 /// X + Y overflows ? (X < 0 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1785 /// X - Y overflows ? (X > 0 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1786 static Instruction *
1787 foldOverflowingAddSubSelect(SelectInst &SI, InstCombiner::BuilderTy &Builder) {
1788  Value *CondVal = SI.getCondition();
1789  Value *TrueVal = SI.getTrueValue();
1790  Value *FalseVal = SI.getFalseValue();
1791 
1792  WithOverflowInst *II;
1793  if (!match(CondVal, m_ExtractValue<1>(m_WithOverflowInst(II))) ||
1794  !match(FalseVal, m_ExtractValue<0>(m_Specific(II))))
1795  return nullptr;
1796 
1797  Value *X = II->getLHS();
1798  Value *Y = II->getRHS();
1799 
1800  auto IsSignedSaturateLimit = [&](Value *Limit, bool IsAdd) {
1801  Type *Ty = Limit->getType();
1802 
1803  ICmpInst::Predicate Pred;
1804  Value *TrueVal, *FalseVal, *Op;
1805  const APInt *C;
1806  if (!match(Limit, m_Select(m_ICmp(Pred, m_Value(Op), m_APInt(C)),
1807  m_Value(TrueVal), m_Value(FalseVal))))
1808  return false;
1809 
1810  auto IsZeroOrOne = [](const APInt &C) {
1811  return C.isNullValue() || C.isOneValue();
1812  };
1813  auto IsMinMax = [&](Value *Min, Value *Max) {
1816  return match(Min, m_SpecificInt(MinVal)) &&
1817  match(Max, m_SpecificInt(MaxVal));
1818  };
1819 
1820  if (Op != X && Op != Y)
1821  return false;
1822 
1823  if (IsAdd) {
1824  // X + Y overflows ? (X <s 0 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1825  // X + Y overflows ? (X <s 1 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1826  // X + Y overflows ? (Y <s 0 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1827  // X + Y overflows ? (Y <s 1 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1828  if (Pred == ICmpInst::ICMP_SLT && IsZeroOrOne(*C) &&
1829  IsMinMax(TrueVal, FalseVal))
1830  return true;
1831  // X + Y overflows ? (X >s 0 ? INTMAX : INTMIN) : X + Y --> sadd_sat X, Y
1832  // X + Y overflows ? (X >s -1 ? INTMAX : INTMIN) : X + Y --> sadd_sat X, Y
1833  // X + Y overflows ? (Y >s 0 ? INTMAX : INTMIN) : X + Y --> sadd_sat X, Y
1834  // X + Y overflows ? (Y >s -1 ? INTMAX : INTMIN) : X + Y --> sadd_sat X, Y
1835  if (Pred == ICmpInst::ICMP_SGT && IsZeroOrOne(*C + 1) &&
1836  IsMinMax(FalseVal, TrueVal))
1837  return true;
1838  } else {
1839  // X - Y overflows ? (X <s 0 ? INTMIN : INTMAX) : X - Y --> ssub_sat X, Y
1840  // X - Y overflows ? (X <s -1 ? INTMIN : INTMAX) : X - Y --> ssub_sat X, Y
1841  if (Op == X && Pred == ICmpInst::ICMP_SLT && IsZeroOrOne(*C + 1) &&
1842  IsMinMax(TrueVal, FalseVal))
1843  return true;
1844  // X - Y overflows ? (X >s -1 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1845  // X - Y overflows ? (X >s -2 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1846  if (Op == X && Pred == ICmpInst::ICMP_SGT && IsZeroOrOne(*C + 2) &&
1847  IsMinMax(FalseVal, TrueVal))
1848  return true;
1849  // X - Y overflows ? (Y <s 0 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1850  // X - Y overflows ? (Y <s 1 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1851  if (Op == Y && Pred == ICmpInst::ICMP_SLT && IsZeroOrOne(*C) &&
1852  IsMinMax(FalseVal, TrueVal))
1853  return true;
1854  // X - Y overflows ? (Y >s 0 ? INTMIN : INTMAX) : X - Y --> ssub_sat X, Y
1855  // X - Y overflows ? (Y >s -1 ? INTMIN : INTMAX) : X - Y --> ssub_sat X, Y
1856  if (Op == Y && Pred == ICmpInst::ICMP_SGT && IsZeroOrOne(*C + 1) &&
1857  IsMinMax(TrueVal, FalseVal))
1858  return true;
1859  }
1860 
1861  return false;
1862  };
1863 
1864  Intrinsic::ID NewIntrinsicID;
1865  if (II->getIntrinsicID() == Intrinsic::uadd_with_overflow &&
1866  match(TrueVal, m_AllOnes()))
1867  // X + Y overflows ? -1 : X + Y -> uadd_sat X, Y
1868  NewIntrinsicID = Intrinsic::uadd_sat;
1869  else if (II->getIntrinsicID() == Intrinsic::usub_with_overflow &&
1870  match(TrueVal, m_Zero()))
1871  // X - Y overflows ? 0 : X - Y -> usub_sat X, Y
1872  NewIntrinsicID = Intrinsic::usub_sat;
1873  else if (II->getIntrinsicID() == Intrinsic::sadd_with_overflow &&
1874  IsSignedSaturateLimit(TrueVal, /*IsAdd=*/true))
1875  // X + Y overflows ? (X <s 0 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1876  // X + Y overflows ? (X <s 1 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1877  // X + Y overflows ? (X >s 0 ? INTMAX : INTMIN) : X + Y --> sadd_sat X, Y
1878  // X + Y overflows ? (X >s -1 ? INTMAX : INTMIN) : X + Y --> sadd_sat X, Y
1879  // X + Y overflows ? (Y <s 0 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1880  // X + Y overflows ? (Y <s 1 ? INTMIN : INTMAX) : X + Y --> sadd_sat X, Y
1881  // X + Y overflows ? (Y >s 0 ? INTMAX : INTMIN) : X + Y --> sadd_sat X, Y
1882  // X + Y overflows ? (Y >s -1 ? INTMAX : INTMIN) : X + Y --> sadd_sat X, Y
1883  NewIntrinsicID = Intrinsic::sadd_sat;
1884  else if (II->getIntrinsicID() == Intrinsic::ssub_with_overflow &&
1885  IsSignedSaturateLimit(TrueVal, /*IsAdd=*/false))
1886  // X - Y overflows ? (X <s 0 ? INTMIN : INTMAX) : X - Y --> ssub_sat X, Y
1887  // X - Y overflows ? (X <s -1 ? INTMIN : INTMAX) : X - Y --> ssub_sat X, Y
1888  // X - Y overflows ? (X >s -1 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1889  // X - Y overflows ? (X >s -2 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1890  // X - Y overflows ? (Y <s 0 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1891  // X - Y overflows ? (Y <s 1 ? INTMAX : INTMIN) : X - Y --> ssub_sat X, Y
1892  // X - Y overflows ? (Y >s 0 ? INTMIN : INTMAX) : X - Y --> ssub_sat X, Y
1893  // X - Y overflows ? (Y >s -1 ? INTMIN : INTMAX) : X - Y --> ssub_sat X, Y
1894  NewIntrinsicID = Intrinsic::ssub_sat;
1895  else
1896  return nullptr;
1897 
1898  Function *F =
1899  Intrinsic::getDeclaration(SI.getModule(), NewIntrinsicID, SI.getType());
1900  return CallInst::Create(F, {X, Y});
1901 }
1902 
1903 Instruction *InstCombiner::foldSelectExtConst(SelectInst &Sel) {
1904  Constant *C;
1905  if (!match(Sel.getTrueValue(), m_Constant(C)) &&
1906  !match(Sel.getFalseValue(), m_Constant(C)))
1907  return nullptr;
1908 
1909  Instruction *ExtInst;
1910  if (!match(Sel.getTrueValue(), m_Instruction(ExtInst)) &&
1911  !match(Sel.getFalseValue(), m_Instruction(ExtInst)))
1912  return nullptr;
1913 
1914  auto ExtOpcode = ExtInst->getOpcode();
1915  if (ExtOpcode != Instruction::ZExt && ExtOpcode != Instruction::SExt)
1916  return nullptr;
1917 
1918  // If we are extending from a boolean type or if we can create a select that
1919  // has the same size operands as its condition, try to narrow the select.
1920  Value *X = ExtInst->getOperand(0);
1921  Type *SmallType = X->getType();
1922  Value *Cond = Sel.getCondition();
1923  auto *Cmp = dyn_cast<CmpInst>(Cond);
1924  if (!SmallType->isIntOrIntVectorTy(1) &&
1925  (!Cmp || Cmp->getOperand(0)->getType() != SmallType))
1926  return nullptr;
1927 
1928  // If the constant is the same after truncation to the smaller type and
1929  // extension to the original type, we can narrow the select.
1930  Type *SelType = Sel.getType();
1931  Constant *TruncC = ConstantExpr::getTrunc(C, SmallType);
1932  Constant *ExtC = ConstantExpr::getCast(ExtOpcode, TruncC, SelType);
1933  if (ExtC == C && ExtInst->hasOneUse()) {
1934  Value *TruncCVal = cast<Value>(TruncC);
1935  if (ExtInst == Sel.getFalseValue())
1936  std::swap(X, TruncCVal);
1937 
1938  // select Cond, (ext X), C --> ext(select Cond, X, C')
1939  // select Cond, C, (ext X) --> ext(select Cond, C', X)
1940  Value *NewSel = Builder.CreateSelect(Cond, X, TruncCVal, "narrow", &Sel);
1941  return CastInst::Create(Instruction::CastOps(ExtOpcode), NewSel, SelType);
1942  }
1943 
1944  // If one arm of the select is the extend of the condition, replace that arm
1945  // with the extension of the appropriate known bool value.
1946  if (Cond == X) {
1947  if (ExtInst == Sel.getTrueValue()) {
1948  // select X, (sext X), C --> select X, -1, C
1949  // select X, (zext X), C --> select X, 1, C
1950  Constant *One = ConstantInt::getTrue(SmallType);
1951  Constant *AllOnesOrOne = ConstantExpr::getCast(ExtOpcode, One, SelType);
1952  return SelectInst::Create(Cond, AllOnesOrOne, C, "", nullptr, &Sel);
1953  } else {
1954  // select X, C, (sext X) --> select X, C, 0
1955  // select X, C, (zext X) --> select X, C, 0
1956  Constant *Zero = ConstantInt::getNullValue(SelType);
1957  return SelectInst::Create(Cond, C, Zero, "", nullptr, &Sel);
1958  }
1959  }
1960 
1961  return nullptr;
1962 }
1963 
1964 /// Try to transform a vector select with a constant condition vector into a
1965 /// shuffle for easier combining with other shuffles and insert/extract.
1966 static Instruction *canonicalizeSelectToShuffle(SelectInst &SI) {
1967  Value *CondVal = SI.getCondition();
1968  Constant *CondC;
1969  if (!CondVal->getType()->isVectorTy() || !match(CondVal, m_Constant(CondC)))
1970  return nullptr;
1971 
1972  unsigned NumElts = cast<VectorType>(CondVal->getType())->getNumElements();
1974  Mask.reserve(NumElts);
1975  for (unsigned i = 0; i != NumElts; ++i) {
1976  Constant *Elt = CondC->getAggregateElement(i);
1977  if (!Elt)
1978  return nullptr;
1979 
1980  if (Elt->isOneValue()) {
1981  // If the select condition element is true, choose from the 1st vector.
1982  Mask.push_back(i);
1983  } else if (Elt->isNullValue()) {
1984  // If the select condition element is false, choose from the 2nd vector.
1985  Mask.push_back(i + NumElts);
1986  } else if (isa<UndefValue>(Elt)) {
1987  // Undef in a select condition (choose one of the operands) does not mean
1988  // the same thing as undef in a shuffle mask (any value is acceptable), so
1989  // give up.
1990  return nullptr;
1991  } else {
1992  // Bail out on a constant expression.
1993  return nullptr;
1994  }
1995  }
1996 
1997  return new ShuffleVectorInst(SI.getTrueValue(), SI.getFalseValue(), Mask);
1998 }
1999 
2000 /// If we have a select of vectors with a scalar condition, try to convert that
2001 /// to a vector select by splatting the condition. A splat may get folded with
2002 /// other operations in IR and having all operands of a select be vector types
2003 /// is likely better for vector codegen.
2004 static Instruction *canonicalizeScalarSelectOfVecs(
2005  SelectInst &Sel, InstCombiner &IC) {
2006  auto *Ty = dyn_cast<VectorType>(Sel.getType());
2007  if (!Ty)
2008  return nullptr;
2009 
2010  // We can replace a single-use extract with constant index.
2011  Value *Cond = Sel.getCondition();
2012  if (!match(Cond, m_OneUse(m_ExtractElt(m_Value(), m_ConstantInt()))))
2013  return nullptr;
2014 
2015  // select (extelt V, Index), T, F --> select (splat V, Index), T, F
2016  // Splatting the extracted condition reduces code (we could directly create a
2017  // splat shuffle of the source vector to eliminate the intermediate step).
2018  unsigned NumElts = Ty->getNumElements();
2019  return IC.replaceOperand(Sel, 0, IC.Builder.CreateVectorSplat(NumElts, Cond));
2020 }
2021 
2022 /// Reuse bitcasted operands between a compare and select:
2023 /// select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
2024 /// bitcast (select (cmp (bitcast C), (bitcast D)), (bitcast C), (bitcast D))
2025 static Instruction *foldSelectCmpBitcasts(SelectInst &Sel,
2026  InstCombiner::BuilderTy &Builder) {
2027  Value *Cond = Sel.getCondition();
2028  Value *TVal = Sel.getTrueValue();
2029  Value *FVal = Sel.getFalseValue();
2030 
2031  CmpInst::Predicate Pred;
2032  Value *A, *B;
2033  if (!match(Cond, m_Cmp(Pred, m_Value(A), m_Value(B))))
2034  return nullptr;
2035 
2036  // The select condition is a compare instruction. If the select's true/false
2037  // values are already the same as the compare operands, there's nothing to do.
2038  if (TVal == A || TVal == B || FVal == A || FVal == B)
2039  return nullptr;
2040 
2041  Value *C, *D;
2042  if (!match(A, m_BitCast(m_Value(C))) || !match(B, m_BitCast(m_Value(D))))
2043  return nullptr;
2044 
2045  // select (cmp (bitcast C), (bitcast D)), (bitcast TSrc), (bitcast FSrc)
2046  Value *TSrc, *FSrc;
2047  if (!match(TVal, m_BitCast(m_Value(TSrc))) ||
2048  !match(FVal, m_BitCast(m_Value(FSrc))))
2049  return nullptr;
2050 
2051  // If the select true/false values are *different bitcasts* of the same source
2052  // operands, make the select operands the same as the compare operands and
2053  // cast the result. This is the canonical select form for min/max.
2054  Value *NewSel;
2055  if (TSrc == C && FSrc == D) {
2056  // select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
2057  // bitcast (select (cmp A, B), A, B)
2058  NewSel = Builder.CreateSelect(Cond, A, B, "", &Sel);
2059  } else if (TSrc == D && FSrc == C) {
2060  // select (cmp (bitcast C), (bitcast D)), (bitcast' D), (bitcast' C) -->
2061  // bitcast (select (cmp A, B), B, A)
2062  NewSel = Builder.CreateSelect(Cond, B, A, "", &Sel);
2063  } else {
2064  return nullptr;
2065  }
2066  return CastInst::CreateBitOrPointerCast(NewSel, Sel.getType());
2067 }
2068 
2069 /// Try to eliminate select instructions that test the returned flag of cmpxchg
2070 /// instructions.
2071 ///
2072 /// If a select instruction tests the returned flag of a cmpxchg instruction and
2073 /// selects between the returned value of the cmpxchg instruction its compare
2074 /// operand, the result of the select will always be equal to its false value.
2075 /// For example:
2076 ///
2077 /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst
2078 /// %1 = extractvalue { i64, i1 } %0, 1
2079 /// %2 = extractvalue { i64, i1 } %0, 0
2080 /// %3 = select i1 %1, i64 %compare, i64 %2
2081 /// ret i64 %3
2082 ///
2083 /// The returned value of the cmpxchg instruction (%2) is the original value
2084 /// located at %ptr prior to any update. If the cmpxchg operation succeeds, %2
2085 /// must have been equal to %compare. Thus, the result of the select is always
2086 /// equal to %2, and the code can be simplified to:
2087 ///
2088 /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst
2089 /// %1 = extractvalue { i64, i1 } %0, 0
2090 /// ret i64 %1
2091 ///
2092 static Value *foldSelectCmpXchg(SelectInst &SI) {
2093  // A helper that determines if V is an extractvalue instruction whose
2094  // aggregate operand is a cmpxchg instruction and whose single index is equal
2095  // to I. If such conditions are true, the helper returns the cmpxchg
2096  // instruction; otherwise, a nullptr is returned.
2097  auto isExtractFromCmpXchg = [](Value *V, unsigned I) -> AtomicCmpXchgInst * {
2098  auto *Extract = dyn_cast<ExtractValueInst>(V);
2099  if (!Extract)
2100  return nullptr;
2101  if (Extract->getIndices()[0] != I)
2102  return nullptr;
2103  return dyn_cast<AtomicCmpXchgInst>(Extract->getAggregateOperand());
2104  };
2105 
2106  // If the select has a single user, and this user is a select instruction that
2107  // we can simplify, skip the cmpxchg simplification for now.
2108  if (SI.hasOneUse())
2109  if (auto *Select = dyn_cast<SelectInst>(SI.user_back()))
2110  if (Select->getCondition() == SI.getCondition())
2111  if (Select->getFalseValue() == SI.getTrueValue() ||
2112  Select->getTrueValue() == SI.getFalseValue())
2113  return nullptr;
2114 
2115  // Ensure the select condition is the returned flag of a cmpxchg instruction.
2116  auto *CmpXchg = isExtractFromCmpXchg(SI.getCondition(), 1);
2117  if (!CmpXchg)
2118  return nullptr;
2119 
2120  // Check the true value case: The true value of the select is the returned
2121  // value of the same cmpxchg used by the condition, and the false value is the
2122  // cmpxchg instruction's compare operand.
2123  if (auto *X = isExtractFromCmpXchg(SI.getTrueValue(), 0))
2124  if (X == CmpXchg && X->getCompareOperand() == SI.getFalseValue())
2125  return SI.getFalseValue();
2126 
2127  // Check the false value case: The false value of the select is the returned
2128  // value of the same cmpxchg used by the condition, and the true value is the
2129  // cmpxchg instruction's compare operand.
2130  if (auto *X = isExtractFromCmpXchg(SI.getFalseValue(), 0))
2131  if (X == CmpXchg && X->getCompareOperand() == SI.getTrueValue())
2132  return SI.getFalseValue();
2133 
2134  return nullptr;
2135 }
2136 
2137 static Instruction *moveAddAfterMinMax(SelectPatternFlavor SPF, Value *X,
2138  Value *Y,
2139  InstCombiner::BuilderTy &Builder) {
2140  assert(SelectPatternResult::isMinOrMax(SPF) && "Expected min/max pattern");
2141  bool IsUnsigned = SPF == SelectPatternFlavor::SPF_UMIN ||
2143  // TODO: If InstSimplify could fold all cases where C2 <= C1, we could change
2144  // the constant value check to an assert.
2145  Value *A;
2146  const APInt *C1, *C2;
2147  if (IsUnsigned && match(X, m_NUWAdd(m_Value(A), m_APInt(C1))) &&
2148  match(Y, m_APInt(C2)) && C2->uge(*C1) && X->hasNUses(2)) {
2149  // umin (add nuw A, C1), C2 --> add nuw (umin A, C2 - C1), C1
2150  // umax (add nuw A, C1), C2 --> add nuw (umax A, C2 - C1), C1
2151  Value *NewMinMax = createMinMax(Builder, SPF, A,
2152  ConstantInt::get(X->getType(), *C2 - *C1));
2154  ConstantInt::get(X->getType(), *C1));
2155  }
2156 
2157  if (!IsUnsigned && match(X, m_NSWAdd(m_Value(A), m_APInt(C1))) &&
2158  match(Y, m_APInt(C2)) && X->hasNUses(2)) {
2159  bool Overflow;
2160  APInt Diff = C2->ssub_ov(*C1, Overflow);
2161  if (!Overflow) {
2162  // smin (add nsw A, C1), C2 --> add nsw (smin A, C2 - C1), C1
2163  // smax (add nsw A, C1), C2 --> add nsw (smax A, C2 - C1), C1
2164  Value *NewMinMax = createMinMax(Builder, SPF, A,
2165  ConstantInt::get(X->getType(), Diff));
2167  ConstantInt::get(X->getType(), *C1));
2168  }
2169  }
2170 
2171  return nullptr;
2172 }
2173 
2174 /// Match a sadd_sat or ssub_sat which is using min/max to clamp the value.
2175 Instruction *InstCombiner::matchSAddSubSat(SelectInst &MinMax1) {
2176  Type *Ty = MinMax1.getType();
2177 
2178  // We are looking for a tree of:
2179  // max(INT_MIN, min(INT_MAX, add(sext(A), sext(B))))
2180  // Where the min and max could be reversed
2181  Instruction *MinMax2;
2182  BinaryOperator *AddSub;
2183  const APInt *MinValue, *MaxValue;
2184  if (match(&MinMax1, m_SMin(m_Instruction(MinMax2), m_APInt(MaxValue)))) {
2185  if (!match(MinMax2, m_SMax(m_BinOp(AddSub), m_APInt(MinValue))))
2186  return nullptr;
2187  } else if (match(&MinMax1,
2188  m_SMax(m_Instruction(MinMax2), m_APInt(MinValue)))) {
2189  if (!match(MinMax2, m_SMin(m_BinOp(AddSub), m_APInt(MaxValue))))
2190  return nullptr;
2191  } else
2192  return nullptr;
2193 
2194  // Check that the constants clamp a saturate, and that the new type would be
2195  // sensible to convert to.
2196  if (!(*MaxValue + 1).isPowerOf2() || -*MinValue != *MaxValue + 1)
2197  return nullptr;
2198  // In what bitwidth can this be treated as saturating arithmetics?
2199  unsigned NewBitWidth = (*MaxValue + 1).logBase2() + 1;
2200  // FIXME: This isn't quite right for vectors, but using the scalar type is a
2201  // good first approximation for what should be done there.
2202  if (!shouldChangeType(Ty->getScalarType()->getIntegerBitWidth(), NewBitWidth))
2203  return nullptr;
2204 
2205  // Also make sure that the number of uses is as expected. The "3"s are for the
2206  // the two items of min/max (the compare and the select).
2207  if (MinMax2->hasNUsesOrMore(3) || AddSub->hasNUsesOrMore(3))
2208  return nullptr;
2209 
2210  // Create the new type (which can be a vector type)
2211  Type *NewTy = Ty->getWithNewBitWidth(NewBitWidth);
2212  // Match the two extends from the add/sub
2213  Value *A, *B;
2214  if(!match(AddSub, m_BinOp(m_SExt(m_Value(A)), m_SExt(m_Value(B)))))
2215  return nullptr;
2216  // And check the incoming values are of a type smaller than or equal to the
2217  // size of the saturation. Otherwise the higher bits can cause different
2218  // results.
2219  if (A->getType()->getScalarSizeInBits() > NewBitWidth ||
2220  B->getType()->getScalarSizeInBits() > NewBitWidth)
2221  return nullptr;
2222 
2223  Intrinsic::ID IntrinsicID;
2224  if (AddSub->getOpcode() == Instruction::Add)
2225  IntrinsicID = Intrinsic::sadd_sat;
2226  else if (AddSub->getOpcode() == Instruction::Sub)
2227  IntrinsicID = Intrinsic::ssub_sat;
2228  else
2229  return nullptr;
2230 
2231  // Finally create and return the sat intrinsic, truncated to the new type
2232  Function *F = Intrinsic::getDeclaration(MinMax1.getModule(), IntrinsicID, NewTy);
2233  Value *AT = Builder.CreateSExt(A, NewTy);
2234  Value *BT = Builder.CreateSExt(B, NewTy);
2235  Value *Sat = Builder.CreateCall(F, {AT, BT});
2236  return CastInst::Create(Instruction::SExt, Sat, Ty);
2237 }
2238 
2239 /// Reduce a sequence of min/max with a common operand.
2240 static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS,
2241  Value *RHS,
2242  InstCombiner::BuilderTy &Builder) {
2243  assert(SelectPatternResult::isMinOrMax(SPF) && "Expected a min/max");
2244  // TODO: Allow FP min/max with nnan/nsz.
2245  if (!LHS->getType()->isIntOrIntVectorTy())
2246  return nullptr;
2247 
2248  // Match 3 of the same min/max ops. Example: umin(umin(), umin()).
2249  Value *A, *B, *C, *D;
2250  SelectPatternResult L = matchSelectPattern(LHS, A, B);
2251  SelectPatternResult R = matchSelectPattern(RHS, C, D);
2252  if (SPF != L.Flavor || L.Flavor != R.Flavor)
2253  return nullptr;
2254 
2255  // Look for a common operand. The use checks are different than usual because
2256  // a min/max pattern typically has 2 uses of each op: 1 by the cmp and 1 by
2257  // the select.
2258  Value *MinMaxOp = nullptr;
2259  Value *ThirdOp = nullptr;
2260  if (!LHS->hasNUsesOrMore(3) && RHS->hasNUsesOrMore(3)) {
2261  // If the LHS is only used in this chain and the RHS is used outside of it,
2262  // reuse the RHS min/max because that will eliminate the LHS.
2263  if (D == A || C == A) {
2264  // min(min(a, b), min(c, a)) --> min(min(c, a), b)
2265  // min(min(a, b), min(a, d)) --> min(min(a, d), b)
2266  MinMaxOp = RHS;
2267  ThirdOp = B;
2268  } else if (D == B || C == B) {
2269  // min(min(a, b), min(c, b)) --> min(min(c, b), a)
2270  // min(min(a, b), min(b, d)) --> min(min(b, d), a)
2271  MinMaxOp = RHS;
2272  ThirdOp = A;
2273  }
2274  } else if (!RHS->hasNUsesOrMore(3)) {
2275  // Reuse the LHS. This will eliminate the RHS.
2276  if (D == A || D == B) {
2277  // min(min(a, b), min(c, a)) --> min(min(a, b), c)
2278  // min(min(a, b), min(c, b)) --> min(min(a, b), c)
2279  MinMaxOp = LHS;
2280  ThirdOp = C;
2281  } else if (C == A || C == B) {
2282  // min(min(a, b), min(b, d)) --> min(min(a, b), d)
2283  // min(min(a, b), min(c, b)) --> min(min(a, b), d)
2284  MinMaxOp = LHS;
2285  ThirdOp = D;
2286  }
2287  }
2288  if (!MinMaxOp || !ThirdOp)
2289  return nullptr;
2290 
2292  Value *CmpABC = Builder.CreateICmp(P, MinMaxOp, ThirdOp);
2293  return SelectInst::Create(CmpABC, MinMaxOp, ThirdOp);
2294 }
2295 
2296 /// Try to reduce a rotate pattern that includes a compare and select into a
2297 /// funnel shift intrinsic. Example:
2298 /// rotl32(a, b) --> (b == 0 ? a : ((a >> (32 - b)) | (a << b)))
2299 /// --> call llvm.fshl.i32(a, a, b)
2300 static Instruction *foldSelectRotate(SelectInst &Sel) {
2301  // The false value of the select must be a rotate of the true value.
2302  Value *Or0, *Or1;
2303  if (!match(Sel.getFalseValue(), m_OneUse(m_Or(m_Value(Or0), m_Value(Or1)))))
2304  return nullptr;
2305 
2306  Value *TVal = Sel.getTrueValue();
2307  Value *SA0, *SA1;
2308  if (!match(Or0, m_OneUse(m_LogicalShift(m_Specific(TVal), m_Value(SA0)))) ||
2309  !match(Or1, m_OneUse(m_LogicalShift(m_Specific(TVal), m_Value(SA1)))))
2310  return nullptr;
2311 
2312  auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode();
2313  auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode();
2314  if (ShiftOpcode0 == ShiftOpcode1)
2315  return nullptr;
2316 
2317  // We have one of these patterns so far:
2318  // select ?, TVal, (or (lshr TVal, SA0), (shl TVal, SA1))
2319  // select ?, TVal, (or (shl TVal, SA0), (lshr TVal, SA1))
2320  // This must be a power-of-2 rotate for a bitmasking transform to be valid.
2321  unsigned Width = Sel.getType()->getScalarSizeInBits();
2322  if (!isPowerOf2_32(Width))
2323  return nullptr;
2324 
2325  // Check the shift amounts to see if they are an opposite pair.
2326  Value *ShAmt;
2327  if (match(SA1, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(SA0)))))
2328  ShAmt = SA0;
2329  else if (match(SA0, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(SA1)))))
2330  ShAmt = SA1;
2331  else
2332  return nullptr;
2333 
2334  // Finally, see if the select is filtering out a shift-by-zero.
2335  Value *Cond = Sel.getCondition();
2336  ICmpInst::Predicate Pred;
2337  if (!match(Cond, m_OneUse(m_ICmp(Pred, m_Specific(ShAmt), m_ZeroInt()))) ||
2338  Pred != ICmpInst::ICMP_EQ)
2339  return nullptr;
2340 
2341  // This is a rotate that avoids shift-by-bitwidth UB in a suboptimal way.
2342  // Convert to funnel shift intrinsic.
2343  bool IsFshl = (ShAmt == SA0 && ShiftOpcode0 == BinaryOperator::Shl) ||
2344  (ShAmt == SA1 && ShiftOpcode1 == BinaryOperator::Shl);
2345  Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
2346  Function *F = Intrinsic::getDeclaration(Sel.getModule(), IID, Sel.getType());
2347  return IntrinsicInst::Create(F, { TVal, TVal, ShAmt });
2348 }
2349 
2350 static Instruction *foldSelectToCopysign(SelectInst &Sel,
2351  InstCombiner::BuilderTy &Builder) {
2352  Value *Cond = Sel.getCondition();
2353  Value *TVal = Sel.getTrueValue();
2354  Value *FVal = Sel.getFalseValue();
2355  Type *SelType = Sel.getType();
2356 
2357  // Match select ?, TC, FC where the constants are equal but negated.
2358  // TODO: Generalize to handle a negated variable operand?
2359  const APFloat *TC, *FC;
2360  if (!match(TVal, m_APFloat(TC)) || !match(FVal, m_APFloat(FC)) ||
2361  !abs(*TC).bitwiseIsEqual(abs(*FC)))
2362  return nullptr;
2363 
2364  assert(TC != FC && "Expected equal select arms to simplify");
2365 
2366  Value *X;
2367  const APInt *C;
2368  bool IsTrueIfSignSet;
2369  ICmpInst::Predicate Pred;
2370  if (!match(Cond, m_OneUse(m_ICmp(Pred, m_BitCast(m_Value(X)), m_APInt(C)))) ||
2371  !isSignBitCheck(Pred, *C, IsTrueIfSignSet) || X->getType() != SelType)
2372  return nullptr;
2373 
2374  // If needed, negate the value that will be the sign argument of the copysign:
2375  // (bitcast X) < 0 ? -TC : TC --> copysign(TC, X)
2376  // (bitcast X) < 0 ? TC : -TC --> copysign(TC, -X)
2377  // (bitcast X) >= 0 ? -TC : TC --> copysign(TC, -X)
2378  // (bitcast X) >= 0 ? TC : -TC --> copysign(TC, X)
2379  if (IsTrueIfSignSet ^ TC->isNegative())
2380  X = Builder.CreateFNegFMF(X, &Sel);
2381 
2382  // Canonicalize the magnitude argument as the positive constant since we do
2383  // not care about its sign.
2384  Value *MagArg = TC->isNegative() ? FVal : TVal;
2385  Function *F = Intrinsic::getDeclaration(Sel.getModule(), Intrinsic::copysign,
2386  Sel.getType());
2387  Instruction *CopySign = IntrinsicInst::Create(F, { MagArg, X });
2388  CopySign->setFastMathFlags(Sel.getFastMathFlags());
2389  return CopySign;
2390 }
2391 
2392 Instruction *InstCombiner::foldVectorSelect(SelectInst &Sel) {
2393  auto *VecTy = dyn_cast<FixedVectorType>(Sel.getType());
2394  if (!VecTy)
2395  return nullptr;
2396 
2397  unsigned NumElts = VecTy->getNumElements();
2398  APInt UndefElts(NumElts, 0);
2399  APInt AllOnesEltMask(APInt::getAllOnesValue(NumElts));
2400  if (Value *V = SimplifyDemandedVectorElts(&Sel, AllOnesEltMask, UndefElts)) {
2401  if (V != &Sel)
2402  return replaceInstUsesWith(Sel, V);
2403  return &Sel;
2404  }
2405 
2406  // A select of a "select shuffle" with a common operand can be rearranged
2407  // to select followed by "select shuffle". Because of poison, this only works
2408  // in the case of a shuffle with no undefined mask elements.
2409  Value *Cond = Sel.getCondition();
2410  Value *TVal = Sel.getTrueValue();
2411  Value *FVal = Sel.getFalseValue();
2412  Value *X, *Y;
2414  if (match(TVal, m_OneUse(m_Shuffle(m_Value(X), m_Value(Y), m_Mask(Mask)))) &&
2415  !is_contained(Mask, UndefMaskElem) &&
2416  cast<ShuffleVectorInst>(TVal)->isSelect()) {
2417  if (X == FVal) {
2418  // select Cond, (shuf_sel X, Y), X --> shuf_sel X, (select Cond, Y, X)
2419  Value *NewSel = Builder.CreateSelect(Cond, Y, X, "sel", &Sel);
2420  return new ShuffleVectorInst(X, NewSel, Mask);
2421  }
2422  if (Y == FVal) {
2423  // select Cond, (shuf_sel X, Y), Y --> shuf_sel (select Cond, X, Y), Y
2424  Value *NewSel = Builder.CreateSelect(Cond, X, Y, "sel", &Sel);
2425  return new ShuffleVectorInst(NewSel, Y, Mask);
2426  }
2427  }
2428  if (match(FVal, m_OneUse(m_Shuffle(m_Value(X), m_Value(Y), m_Mask(Mask)))) &&
2429  !is_contained(Mask, UndefMaskElem) &&
2430  cast<ShuffleVectorInst>(FVal)->isSelect()) {
2431  if (X == TVal) {
2432  // select Cond, X, (shuf_sel X, Y) --> shuf_sel X, (select Cond, X, Y)
2433  Value *NewSel = Builder.CreateSelect(Cond, X, Y, "sel", &Sel);
2434  return new ShuffleVectorInst(X, NewSel, Mask);
2435  }
2436  if (Y == TVal) {
2437  // select Cond, Y, (shuf_sel X, Y) --> shuf_sel (select Cond, Y, X), Y
2438  Value *NewSel = Builder.CreateSelect(Cond, Y, X, "sel", &Sel);
2439  return new ShuffleVectorInst(NewSel, Y, Mask);
2440  }
2441  }
2442 
2443  return nullptr;
2444 }
2445 
2446 static Instruction *foldSelectToPhiImpl(SelectInst &Sel, BasicBlock *BB,
2447  const DominatorTree &DT,
2448  InstCombiner::BuilderTy &Builder) {
2449  // Find the block's immediate dominator that ends with a conditional branch
2450  // that matches select's condition (maybe inverted).
2451  auto *IDomNode = DT[BB]->getIDom();
2452  if (!IDomNode)
2453  return nullptr;
2454  BasicBlock *IDom = IDomNode->getBlock();
2455 
2456  Value *Cond = Sel.getCondition();
2457  Value *IfTrue, *IfFalse;
2458  BasicBlock *TrueSucc, *FalseSucc;
2459  if (match(IDom->getTerminator(),
2460  m_Br(m_Specific(Cond), m_BasicBlock(TrueSucc),
2461  m_BasicBlock(FalseSucc)))) {
2462  IfTrue = Sel.getTrueValue();
2463  IfFalse = Sel.getFalseValue();
2464  } else if (match(IDom->getTerminator(),
2465  m_Br(m_Not(m_Specific(Cond)), m_BasicBlock(TrueSucc),
2466  m_BasicBlock(FalseSucc)))) {
2467  IfTrue = Sel.getFalseValue();
2468  IfFalse = Sel.getTrueValue();
2469  } else
2470  return nullptr;
2471 
2472  // We want to replace select %cond, %a, %b with a phi that takes value %a
2473  // for all incoming edges that are dominated by condition `%cond == true`,
2474  // and value %b for edges dominated by condition `%cond == false`. If %a
2475  // or %b are also phis from the same basic block, we can go further and take
2476  // their incoming values from the corresponding blocks.
2477  BasicBlockEdge TrueEdge(IDom, TrueSucc);
2478  BasicBlockEdge FalseEdge(IDom, FalseSucc);
2480  for (auto *Pred : predecessors(BB)) {
2481  // Check implication.
2482  BasicBlockEdge Incoming(Pred, BB);
2483  if (DT.dominates(TrueEdge, Incoming))
2484  Inputs[Pred] = IfTrue->DoPHITranslation(BB, Pred);
2485  else if (DT.dominates(FalseEdge, Incoming))
2486  Inputs[Pred] = IfFalse->DoPHITranslation(BB, Pred);
2487  else
2488  return nullptr;
2489  // Check availability.
2490  if (auto *Insn = dyn_cast<Instruction>(Inputs[Pred]))
2491  if (!DT.dominates(Insn, Pred->getTerminator()))
2492  return nullptr;
2493  }
2494 
2495  Builder.SetInsertPoint(&*BB->begin());
2496  auto *PN = Builder.CreatePHI(Sel.getType(), Inputs.size());
2497  for (auto *Pred : predecessors(BB))
2498  PN->addIncoming(Inputs[Pred], Pred);
2499  PN->takeName(&Sel);
2500  return PN;
2501 }
2502 
2503 static Instruction *foldSelectToPhi(SelectInst &Sel, const DominatorTree &DT,
2504  InstCombiner::BuilderTy &Builder) {
2505  // Try to replace this select with Phi in one of these blocks.
2506  SmallSetVector<BasicBlock *, 4> CandidateBlocks;
2507  CandidateBlocks.insert(Sel.getParent());
2508  for (Value *V : Sel.operands())
2509  if (auto *I = dyn_cast<Instruction>(V))
2510  CandidateBlocks.insert(I->getParent());
2511 
2512  for (BasicBlock *BB : CandidateBlocks)
2513  if (auto *PN = foldSelectToPhiImpl(Sel, BB, DT, Builder))
2514  return PN;
2515  return nullptr;
2516 }
2517 
2519  Value *CondVal = SI.getCondition();
2520  Value *TrueVal = SI.getTrueValue();
2521  Value *FalseVal = SI.getFalseValue();
2522  Type *SelType = SI.getType();
2523 
2524  // FIXME: Remove this workaround when freeze related patches are done.
2525  // For select with undef operand which feeds into an equality comparison,
2526  // don't simplify it so loop unswitch can know the equality comparison
2527  // may have an undef operand. This is a workaround for PR31652 caused by
2528  // descrepancy about branch on undef between LoopUnswitch and GVN.
2529  if (isa<UndefValue>(TrueVal) || isa<UndefValue>(FalseVal)) {
2530  if (llvm::any_of(SI.users(), [&](User *U) {
2531  ICmpInst *CI = dyn_cast<ICmpInst>(U);
2532  if (CI && CI->isEquality())
2533  return true;
2534  return false;
2535  })) {
2536  return nullptr;
2537  }
2538  }
2539 
2540  if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal,
2541  SQ.getWithInstruction(&SI)))
2542  return replaceInstUsesWith(SI, V);
2543 
2544  if (Instruction *I = canonicalizeSelectToShuffle(SI))
2545  return I;
2546 
2547  if (Instruction *I = canonicalizeScalarSelectOfVecs(SI, *this))
2548  return I;
2549 
2550  CmpInst::Predicate Pred;
2551 
2552  if (SelType->isIntOrIntVectorTy(1) &&
2553  TrueVal->getType() == CondVal->getType()) {
2554  if (match(TrueVal, m_One())) {
2555  // Change: A = select B, true, C --> A = or B, C
2556  return BinaryOperator::CreateOr(CondVal, FalseVal);
2557  }
2558  if (match(TrueVal, m_Zero())) {
2559  // Change: A = select B, false, C --> A = and !B, C
2560  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
2561  return BinaryOperator::CreateAnd(NotCond, FalseVal);
2562  }
2563  if (match(FalseVal, m_Zero())) {
2564  // Change: A = select B, C, false --> A = and B, C
2565  return BinaryOperator::CreateAnd(CondVal, TrueVal);
2566  }
2567  if (match(FalseVal, m_One())) {
2568  // Change: A = select B, C, true --> A = or !B, C
2569  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
2570  return BinaryOperator::CreateOr(NotCond, TrueVal);
2571  }
2572 
2573  // select a, a, b -> a | b
2574  // select a, b, a -> a & b
2575  if (CondVal == TrueVal)
2576  return BinaryOperator::CreateOr(CondVal, FalseVal);
2577  if (CondVal == FalseVal)
2578  return BinaryOperator::CreateAnd(CondVal, TrueVal);
2579 
2580  // select a, ~a, b -> (~a) & b
2581  // select a, b, ~a -> (~a) | b
2582  if (match(TrueVal, m_Not(m_Specific(CondVal))))
2583  return BinaryOperator::CreateAnd(TrueVal, FalseVal);
2584  if (match(FalseVal, m_Not(m_Specific(CondVal))))
2585  return BinaryOperator::CreateOr(TrueVal, FalseVal);
2586  }
2587 
2588  // Selecting between two integer or vector splat integer constants?
2589  //
2590  // Note that we don't handle a scalar select of vectors:
2591  // select i1 %c, <2 x i8> <1, 1>, <2 x i8> <0, 0>
2592  // because that may need 3 instructions to splat the condition value:
2593  // extend, insertelement, shufflevector.
2594  if (SelType->isIntOrIntVectorTy() &&
2595  CondVal->getType()->isVectorTy() == SelType->isVectorTy()) {
2596  // select C, 1, 0 -> zext C to int
2597  if (match(TrueVal, m_One()) && match(FalseVal, m_Zero()))
2598  return new ZExtInst(CondVal, SelType);
2599 
2600  // select C, -1, 0 -> sext C to int
2601  if (match(TrueVal, m_AllOnes()) && match(FalseVal, m_Zero()))
2602  return new SExtInst(CondVal, SelType);
2603 
2604  // select C, 0, 1 -> zext !C to int
2605  if (match(TrueVal, m_Zero()) && match(FalseVal, m_One())) {
2606  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
2607  return new ZExtInst(NotCond, SelType);
2608  }
2609 
2610  // select C, 0, -1 -> sext !C to int
2611  if (match(TrueVal, m_Zero()) && match(FalseVal, m_AllOnes())) {
2612  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
2613  return new SExtInst(NotCond, SelType);
2614  }
2615  }
2616 
2617  // See if we are selecting two values based on a comparison of the two values.
2618  if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
2619  Value *Cmp0 = FCI->getOperand(0), *Cmp1 = FCI->getOperand(1);
2620  if ((Cmp0 == TrueVal && Cmp1 == FalseVal) ||
2621  (Cmp0 == FalseVal && Cmp1 == TrueVal)) {
2622  // Canonicalize to use ordered comparisons by swapping the select
2623  // operands.
2624  //
2625  // e.g.
2626  // (X ugt Y) ? X : Y -> (X ole Y) ? Y : X
2627  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
2628  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
2629  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
2630  // FIXME: The FMF should propagate from the select, not the fcmp.
2631  Builder.setFastMathFlags(FCI->getFastMathFlags());
2632  Value *NewCond = Builder.CreateFCmp(InvPred, Cmp0, Cmp1,
2633  FCI->getName() + ".inv");
2634  Value *NewSel = Builder.CreateSelect(NewCond, FalseVal, TrueVal);
2635  return replaceInstUsesWith(SI, NewSel);
2636  }
2637 
2638  // NOTE: if we wanted to, this is where to detect MIN/MAX
2639  }
2640  }
2641 
2642  // Canonicalize select with fcmp to fabs(). -0.0 makes this tricky. We need
2643  // fast-math-flags (nsz) or fsub with +0.0 (not fneg) for this to work. We
2644  // also require nnan because we do not want to unintentionally change the
2645  // sign of a NaN value.
2646  // FIXME: These folds should test/propagate FMF from the select, not the
2647  // fsub or fneg.
2648  // (X <= +/-0.0) ? (0.0 - X) : X --> fabs(X)
2649  Instruction *FSub;
2650  if (match(CondVal, m_FCmp(Pred, m_Specific(FalseVal), m_AnyZeroFP())) &&
2651  match(TrueVal, m_FSub(m_PosZeroFP(), m_Specific(FalseVal))) &&
2652  match(TrueVal, m_Instruction(FSub)) && FSub->hasNoNaNs() &&
2653  (Pred == FCmpInst::FCMP_OLE || Pred == FCmpInst::FCMP_ULE)) {
2654  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, FalseVal, FSub);
2655  return replaceInstUsesWith(SI, Fabs);
2656  }
2657  // (X > +/-0.0) ? X : (0.0 - X) --> fabs(X)
2658  if (match(CondVal, m_FCmp(Pred, m_Specific(TrueVal), m_AnyZeroFP())) &&
2659  match(FalseVal, m_FSub(m_PosZeroFP(), m_Specific(TrueVal))) &&
2660  match(FalseVal, m_Instruction(FSub)) && FSub->hasNoNaNs() &&
2661  (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_UGT)) {
2662  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, TrueVal, FSub);
2663  return replaceInstUsesWith(SI, Fabs);
2664  }
2665  // With nnan and nsz:
2666  // (X < +/-0.0) ? -X : X --> fabs(X)
2667  // (X <= +/-0.0) ? -X : X --> fabs(X)
2668  Instruction *FNeg;
2669  if (match(CondVal, m_FCmp(Pred, m_Specific(FalseVal), m_AnyZeroFP())) &&
2670  match(TrueVal, m_FNeg(m_Specific(FalseVal))) &&
2671  match(TrueVal, m_Instruction(FNeg)) &&
2672  FNeg->hasNoNaNs() && FNeg->hasNoSignedZeros() &&
2673  (Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_OLE ||
2674  Pred == FCmpInst::FCMP_ULT || Pred == FCmpInst::FCMP_ULE)) {
2675  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, FalseVal, FNeg);
2676  return replaceInstUsesWith(SI, Fabs);
2677  }
2678  // With nnan and nsz:
2679  // (X > +/-0.0) ? X : -X --> fabs(X)
2680  // (X >= +/-0.0) ? X : -X --> fabs(X)
2681  if (match(CondVal, m_FCmp(Pred, m_Specific(TrueVal), m_AnyZeroFP())) &&
2682  match(FalseVal, m_FNeg(m_Specific(TrueVal))) &&
2683  match(FalseVal, m_Instruction(FNeg)) &&
2684  FNeg->hasNoNaNs() && FNeg->hasNoSignedZeros() &&
2685  (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_OGE ||
2686  Pred == FCmpInst::FCMP_UGT || Pred == FCmpInst::FCMP_UGE)) {
2687  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, TrueVal, FNeg);
2688  return replaceInstUsesWith(SI, Fabs);
2689  }
2690 
2691  // See if we are selecting two values based on a comparison of the two values.
2692  if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
2693  if (Instruction *Result = foldSelectInstWithICmp(SI, ICI))
2694  return Result;
2695 
2696  if (Instruction *Add = foldAddSubSelect(SI, Builder))
2697  return Add;
2698  if (Instruction *Add = foldOverflowingAddSubSelect(SI, Builder))
2699  return Add;
2700  if (Instruction *Or = foldSetClearBits(SI, Builder))
2701  return Or;
2702 
2703  // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
2704  auto *TI = dyn_cast<Instruction>(TrueVal);
2705  auto *FI = dyn_cast<Instruction>(FalseVal);
2706  if (TI && FI && TI->getOpcode() == FI->getOpcode())
2707  if (Instruction *IV = foldSelectOpOp(SI, TI, FI))
2708  return IV;
2709 
2710  if (Instruction *I = foldSelectExtConst(SI))
2711  return I;
2712 
2713  // See if we can fold the select into one of our operands.
2714  if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) {
2715  if (Instruction *FoldI = foldSelectIntoOp(SI, TrueVal, FalseVal))
2716  return FoldI;
2717 
2718  Value *LHS, *RHS;
2719  Instruction::CastOps CastOp;
2720  SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp);
2721  auto SPF = SPR.Flavor;
2722  if (SPF) {
2723  Value *LHS2, *RHS2;
2724  if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor)
2725  if (Instruction *R = foldSPFofSPF(cast<Instruction>(LHS), SPF2, LHS2,
2726  RHS2, SI, SPF, RHS))
2727  return R;
2728  if (SelectPatternFlavor SPF2 = matchSelectPattern(RHS, LHS2, RHS2).Flavor)
2729  if (Instruction *R = foldSPFofSPF(cast<Instruction>(RHS), SPF2, LHS2,
2730  RHS2, SI, SPF, LHS))
2731  return R;
2732  // TODO.
2733  // ABS(-X) -> ABS(X)
2734  }
2735 
2737  // Canonicalize so that
2738  // - type casts are outside select patterns.
2739  // - float clamp is transformed to min/max pattern
2740 
2741  bool IsCastNeeded = LHS->getType() != SelType;
2742  Value *CmpLHS = cast<CmpInst>(CondVal)->getOperand(0);
2743  Value *CmpRHS = cast<CmpInst>(CondVal)->getOperand(1);
2744  if (IsCastNeeded ||
2745  (LHS->getType()->isFPOrFPVectorTy() &&
2746  ((CmpLHS != LHS && CmpLHS != RHS) ||
2747  (CmpRHS != LHS && CmpRHS != RHS)))) {
2748  CmpInst::Predicate MinMaxPred = getMinMaxPred(SPF, SPR.Ordered);
2749 
2750  Value *Cmp;
2751  if (CmpInst::isIntPredicate(MinMaxPred)) {
2752  Cmp = Builder.CreateICmp(MinMaxPred, LHS, RHS);
2753  } else {
2754  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
2755  auto FMF =
2756  cast<FPMathOperator>(SI.getCondition())->getFastMathFlags();
2757  Builder.setFastMathFlags(FMF);
2758  Cmp = Builder.CreateFCmp(MinMaxPred, LHS, RHS);
2759  }
2760 
2761  Value *NewSI = Builder.CreateSelect(Cmp, LHS, RHS, SI.getName(), &SI);
2762  if (!IsCastNeeded)
2763  return replaceInstUsesWith(SI, NewSI);
2764 
2765  Value *NewCast = Builder.CreateCast(CastOp, NewSI, SelType);
2766  return replaceInstUsesWith(SI, NewCast);
2767  }
2768 
2769  // MAX(~a, ~b) -> ~MIN(a, b)
2770  // MAX(~a, C) -> ~MIN(a, ~C)
2771  // MIN(~a, ~b) -> ~MAX(a, b)
2772  // MIN(~a, C) -> ~MAX(a, ~C)
2773  auto moveNotAfterMinMax = [&](Value *X, Value *Y) -> Instruction * {
2774  Value *A;
2775  if (match(X, m_Not(m_Value(A))) && !X->hasNUsesOrMore(3) &&
2776  !isFreeToInvert(A, A->hasOneUse()) &&
2777  // Passing false to only consider m_Not and constants.
2778  isFreeToInvert(Y, false)) {
2779  Value *B = Builder.CreateNot(Y);
2780  Value *NewMinMax = createMinMax(Builder, getInverseMinMaxFlavor(SPF),
2781  A, B);
2782  // Copy the profile metadata.
2783  if (MDNode *MD = SI.getMetadata(LLVMContext::MD_prof)) {
2784  cast<SelectInst>(NewMinMax)->setMetadata(LLVMContext::MD_prof, MD);
2785  // Swap the metadata if the operands are swapped.
2786  if (X == SI.getFalseValue() && Y == SI.getTrueValue())
2787  cast<SelectInst>(NewMinMax)->swapProfMetadata();
2788  }
2789 
2790  return BinaryOperator::CreateNot(NewMinMax);
2791  }
2792 
2793  return nullptr;
2794  };
2795 
2796  if (Instruction *I = moveNotAfterMinMax(LHS, RHS))
2797  return I;
2798  if (Instruction *I = moveNotAfterMinMax(RHS, LHS))
2799  return I;
2800 
2801  if (Instruction *I = moveAddAfterMinMax(SPF, LHS, RHS, Builder))
2802  return I;
2803 
2804  if (Instruction *I = factorizeMinMaxTree(SPF, LHS, RHS, Builder))
2805  return I;
2806  if (Instruction *I = matchSAddSubSat(SI))
2807  return I;
2808  }
2809  }
2810 
2811  // Canonicalize select of FP values where NaN and -0.0 are not valid as
2812  // minnum/maxnum intrinsics.
2813  if (isa<FPMathOperator>(SI) && SI.hasNoNaNs() && SI.hasNoSignedZeros()) {
2814  Value *X, *Y;
2815  if (match(&SI, m_OrdFMax(m_Value(X), m_Value(Y))))
2816  return replaceInstUsesWith(
2817  SI, Builder.CreateBinaryIntrinsic(Intrinsic::maxnum, X, Y, &SI));
2818 
2819  if (match(&SI, m_OrdFMin(m_Value(X), m_Value(Y))))
2820  return replaceInstUsesWith(
2821  SI, Builder.CreateBinaryIntrinsic(Intrinsic::minnum, X, Y, &SI));
2822  }
2823 
2824  // See if we can fold the select into a phi node if the condition is a select.
2825  if (auto *PN = dyn_cast<PHINode>(SI.getCondition()))
2826  // The true/false values have to be live in the PHI predecessor's blocks.
2827  if (canSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
2828  canSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
2829  if (Instruction *NV = foldOpIntoPhi(SI, PN))
2830  return NV;
2831 
2832  if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
2833  if (TrueSI->getCondition()->getType() == CondVal->getType()) {
2834  // select(C, select(C, a, b), c) -> select(C, a, c)
2835  if (TrueSI->getCondition() == CondVal) {
2836  if (SI.getTrueValue() == TrueSI->getTrueValue())
2837  return nullptr;
2838  return replaceOperand(SI, 1, TrueSI->getTrueValue());
2839  }
2840  // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
2841  // We choose this as normal form to enable folding on the And and shortening
2842  // paths for the values (this helps GetUnderlyingObjects() for example).
2843  if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
2844  Value *And = Builder.CreateAnd(CondVal, TrueSI->getCondition());
2845  replaceOperand(SI, 0, And);
2846  replaceOperand(SI, 1, TrueSI->getTrueValue());
2847  return &SI;
2848  }
2849  }
2850  }
2851  if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
2852  if (FalseSI->getCondition()->getType() == CondVal->getType()) {
2853  // select(C, a, select(C, b, c)) -> select(C, a, c)
2854  if (FalseSI->getCondition() == CondVal) {
2855  if (SI.getFalseValue() == FalseSI->getFalseValue())
2856  return nullptr;
2857  return replaceOperand(SI, 2, FalseSI->getFalseValue());
2858  }
2859  // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
2860  if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
2861  Value *Or = Builder.CreateOr(CondVal, FalseSI->getCondition());
2862  replaceOperand(SI, 0, Or);
2863  replaceOperand(SI, 2, FalseSI->getFalseValue());
2864  return &SI;
2865  }
2866  }
2867  }
2868 
2869  auto canMergeSelectThroughBinop = [](BinaryOperator *BO) {
2870  // The select might be preventing a division by 0.
2871  switch (BO->getOpcode()) {
2872  default:
2873  return true;
2874  case Instruction::SRem:
2875  case Instruction::URem:
2876  case Instruction::SDiv:
2877  case Instruction::UDiv:
2878  return false;
2879  }
2880  };
2881 
2882  // Try to simplify a binop sandwiched between 2 selects with the same
2883  // condition.
2884  // select(C, binop(select(C, X, Y), W), Z) -> select(C, binop(X, W), Z)
2885  BinaryOperator *TrueBO;
2886  if (match(TrueVal, m_OneUse(m_BinOp(TrueBO))) &&
2887  canMergeSelectThroughBinop(TrueBO)) {
2888  if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(0))) {
2889  if (TrueBOSI->getCondition() == CondVal) {
2890  replaceOperand(*TrueBO, 0, TrueBOSI->getTrueValue());
2891  Worklist.push(TrueBO);
2892  return &SI;
2893  }
2894  }
2895  if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(1))) {
2896  if (TrueBOSI->getCondition() == CondVal) {
2897  replaceOperand(*TrueBO, 1, TrueBOSI->getTrueValue());
2898  Worklist.push(TrueBO);
2899  return &SI;
2900  }
2901  }
2902  }
2903 
2904  // select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W))
2905  BinaryOperator *FalseBO;
2906  if (match(FalseVal, m_OneUse(m_BinOp(FalseBO))) &&
2907  canMergeSelectThroughBinop(FalseBO)) {
2908  if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(0))) {
2909  if (FalseBOSI->getCondition() == CondVal) {
2910  replaceOperand(*FalseBO, 0, FalseBOSI->getFalseValue());
2911  Worklist.push(FalseBO);
2912  return &SI;
2913  }
2914  }
2915  if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(1))) {
2916  if (FalseBOSI->getCondition() == CondVal) {
2917  replaceOperand(*FalseBO, 1, FalseBOSI->getFalseValue());
2918  Worklist.push(FalseBO);
2919  return &SI;
2920  }
2921  }
2922  }
2923 
2924  Value *NotCond;
2925  if (match(CondVal, m_Not(m_Value(NotCond)))) {
2926  replaceOperand(SI, 0, NotCond);
2927  SI.swapValues();
2928  SI.swapProfMetadata();
2929  return &SI;
2930  }
2931 
2932  if (Instruction *I = foldVectorSelect(SI))
2933  return I;
2934 
2935  // If we can compute the condition, there's no need for a select.
2936  // Like the above fold, we are attempting to reduce compile-time cost by
2937  // putting this fold here with limitations rather than in InstSimplify.
2938  // The motivation for this call into value tracking is to take advantage of
2939  // the assumption cache, so make sure that is populated.
2940  if (!CondVal->getType()->isVectorTy() && !AC.assumptions().empty()) {
2941  KnownBits Known(1);
2942  computeKnownBits(CondVal, Known, 0, &SI);
2943  if (Known.One.isOneValue())
2944  return replaceInstUsesWith(SI, TrueVal);
2945  if (Known.Zero.isOneValue())
2946  return replaceInstUsesWith(SI, FalseVal);
2947  }
2948 
2949  if (Instruction *BitCastSel = foldSelectCmpBitcasts(SI, Builder))
2950  return BitCastSel;
2951 
2952  // Simplify selects that test the returned flag of cmpxchg instructions.
2953  if (Value *V = foldSelectCmpXchg(SI))
2954  return replaceInstUsesWith(SI, V);
2955 
2956  if (Instruction *Select = foldSelectBinOpIdentity(SI, TLI, *this))
2957  return Select;
2958 
2959  if (Instruction *Rot = foldSelectRotate(SI))
2960  return Rot;
2961 
2962  if (Instruction *Copysign = foldSelectToCopysign(SI, Builder))
2963  return Copysign;
2964 
2965  if (Instruction *PN = foldSelectToPhi(SI, DT, Builder))
2966  return replaceInstUsesWith(SI, PN);
2967 
2968  return nullptr;
2969 }
MaxMin_match< ICmpInst, LHS, RHS, umin_pred_ty > m_UMin(const LHS &L, const RHS &R)
cst_pred_ty< icmp_pred_with_threshold > m_SpecificInt_ICMP(ICmpInst::Predicate Predicate, const APInt &Threshold)
Match an integer or vector with every element comparing &#39;pred&#39; (eg/ne/...) to Threshold.
Definition: PatternMatch.h:542
bool isFPPredicate() const
Definition: InstrTypes.h:819
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:955
uint64_t CallInst * C
void computeKnownBits(const Value *V, KnownBits &Known, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, OptimizationRemarkEmitter *ORE=nullptr, bool UseInstrInfo=true)
Determine which bits of V are known to be either zero or one and return them in the KnownZero/KnownOn...
static bool isSelect01(const APInt &C1I, const APInt &C2I)
static ConstantInt * getFalse(LLVMContext &Context)
Definition: Constants.cpp:749
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:76
This class is the base class for the comparison instructions.
Definition: InstrTypes.h:715
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
void setFastMathFlags(FastMathFlags FMF)
Convenience function for setting multiple fast-math flags on this instruction, which must be an opera...
LLVM_NODISCARD std::enable_if_t< !is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type > dyn_cast(const Y &Val)
Definition: Casting.h:334
bool hasNoSignedZeros() const
Determine whether the no-signed-zeros flag is set.
class_match< CmpInst > m_Cmp()
Matches any compare instruction and ignore it.
Definition: PatternMatch.h:89
void addIncoming(Value *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
This instruction extracts a struct member or array element value from an aggregate value...
ThreeOps_match< Cond, LHS, RHS, Instruction::Select > m_Select(const Cond &C, const LHS &L, const RHS &R)
Matches SelectInst.
static APInt getAllOnesValue(unsigned numBits)
Get the all-ones value.
Definition: APInt.h:566
BinaryOp_match< LHS, RHS, Instruction::Sub > m_Sub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:852
is_zero m_Zero()
Match any null constant or a vector with all elements equal to 0.
Definition: PatternMatch.h:451
DiagnosticInfoOptimizationBase::Argument NV
static BinaryOperator * CreateNot(Value *Op, const Twine &Name="", Instruction *InsertBefore=nullptr)
Unsigned minimum.
signed greater or equal
Definition: InstrTypes.h:753
brc_match< Cond_t, bind_ty< BasicBlock >, bind_ty< BasicBlock > > m_Br(const Cond_t &C, BasicBlock *&T, BasicBlock *&F)
This class represents lattice values for constants.
Definition: AllocatorList.h:23
BinaryOps getOpcode() const
Definition: InstrTypes.h:395
Represents an op.with.overflow intrinsic.
Value * CreateCast(Instruction::CastOps Op, Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:2087
bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred, Value *&X, APInt &Mask, bool LookThroughTrunc=true)
Decompose an icmp into the form ((X & Mask) pred 0) if possible.
An instruction that atomically checks whether a specified value is in a memory location, and, if it is, stores a new value there.
Definition: Instructions.h:521
static CallInst * Create(FunctionType *Ty, Value *F, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Value * CreateLShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1280
unsigned less than
Definition: InstrTypes.h:750
This class represents zero extension of integer types.
0 1 0 0 True if ordered and less than
Definition: InstrTypes.h:731
static GetElementPtrInst * Create(Type *PointeeType, Value *Ptr, ArrayRef< Value *> IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Definition: Instructions.h:930
bool slt(const APInt &RHS) const
Signed less than comparison.
Definition: APInt.h:1226
class_match< Constant > m_Constant()
Match an arbitrary Constant and ignore it.
Definition: PatternMatch.h:100
static bool isCanonicalPredicate(CmpInst::Predicate Pred)
Predicate canonicalization reduces the number of patterns that need to be matched by other transforms...
const Value * getTrueValue() const
constexpr int UndefMaskElem
BinaryOp_match< LHS, RHS, Instruction::AShr > m_AShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:985
This instruction constructs a fixed permutation of two input vectors.
static SelectInst * Create(Value *C, Value *S1, Value *S2, const Twine &NameStr="", Instruction *InsertBefore=nullptr, Instruction *MDFrom=nullptr)
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:826
static unsigned getSelectFoldableOperands(BinaryOperator *I)
We want to turn code that looks like this: C = or A, B D = select cond, C, A into: C = select cond...
static CastInst * CreateBitOrPointerCast(Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Create a BitCast, a PtrToInt, or an IntToPTr cast instruction.
bool sgt(const APInt &RHS) const
Signed greater than comparison.
Definition: APInt.h:1296
static bool isEquality(Predicate P)
Return true if this predicate is either EQ or NE.
void setArgOperand(unsigned i, Value *v)
Definition: InstrTypes.h:1264
Metadata node.
Definition: Metadata.h:870
SelectPatternFlavor getInverseMinMaxFlavor(SelectPatternFlavor SPF)
Return the inverse minimum/maximum flavor of the specified flavor.
F(f)
This class represents a sign extension of integer types.
BinaryOp_match< LHS, RHS, Instruction::FSub > m_FSub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:858
static Constant * getSub(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2492
const Instruction * getTerminator() const LLVM_READONLY
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:150
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:231
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:725
void reserve(size_type N)
Definition: SmallVector.h:415
bool sle(const APInt &RHS) const
Signed less or equal comparison.
Definition: APInt.h:1261
void copyIRFlags(const Value *V, bool IncludeWrapFlags=true)
Convenience method to copy supported exact, fast-math, and (optionally) wrapping flags from V to this...
AnyBinaryOp_match< LHS, RHS, true > m_c_BinOp(const LHS &L, const RHS &R)
Matches a BinaryOperator with LHS and RHS in either order.
const Value * DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB) const
Translate PHI node to its predecessor from the given basic block.
Definition: Value.cpp:818
static bool isFreeToInvert(Value *V, bool WillInvertAllUses)
Return true if the specified value is free to invert (apply ~ to).
cst_pred_ty< is_zero_int > m_ZeroInt()
Match an integer 0 or a vector with all elements equal to 0.
Definition: PatternMatch.h:438
bool Ordered
Only applicable if Flavor is SPF_FMINNUM or SPF_FMAXNUM.
static APInt getSignedMaxValue(unsigned numBits)
Gets maximum signed value of APInt for a specific bit width.
Definition: APInt.h:539
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1569
Signed maximum.
BinOpPred_match< LHS, RHS, is_logical_shift_op > m_LogicalShift(const LHS &L, const RHS &R)
Matches logical shift operations.
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1320
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:328
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:289
Value * getArgOperand(unsigned i) const
Definition: InstrTypes.h:1259
static BinaryOperator * CreateNSW(BinaryOps Opc, Value *V1, Value *V2, const Twine &Name="")
Definition: InstrTypes.h:286
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
CmpClass_match< LHS, RHS, FCmpInst, FCmpInst::Predicate > m_FCmp(FCmpInst::Predicate &Pred, const LHS &L, const RHS &R)
static UnaryOperator * CreateFNegFMF(Value *Op, Instruction *FMFSource, const Twine &Name="", Instruction *InsertBefore=nullptr)
Definition: InstrTypes.h:166
static Value * foldSelectICmpAnd(SelectInst &Sel, ICmpInst *Cmp, InstCombiner::BuilderTy &Builder)
This folds: select (icmp eq (and X, C1)), TC, FC iff C1 is a power 2 and the difference between TC an...
BinaryOp_match< LHS, RHS, Instruction::Xor > m_Xor(const LHS &L, const RHS &R)
Definition: PatternMatch.h:967
This class represents the LLVM &#39;select&#39; instruction.
Predicate getInversePredicate() const
For example, EQ -> NE, UGT -> ULE, SLT -> SGE, OEQ -> UNE, UGT -> OLE, OLT -> UGE, etc.
Definition: InstrTypes.h:826
Absolute value.
Value * CreateFCmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:2285
static Instruction * foldSelectBinOpIdentity(SelectInst &Sel, const TargetLibraryInfo &TLI, InstCombiner &IC)
Replace a select operand based on an equality comparison with the identity constant of a binop...
static Optional< unsigned > getOpcode(ArrayRef< VPValue *> Values)
Returns the opcode of Values or ~0 if they do not all agree.
Definition: VPlanSLP.cpp:196
static Value * foldSelectICmpLshrAshr(const ICmpInst *IC, Value *TrueVal, Value *FalseVal, InstCombiner::BuilderTy &Builder)
We want to turn: (select (icmp sgt x, C), lshr (X, Y), ashr (X, Y)); iff C s>= -1 (select (icmp slt x...
bool isUnsigned() const
Definition: InstrTypes.h:903
CastClass_match< OpTy, Instruction::Trunc > m_Trunc(const OpTy &Op)
Matches Trunc.
The core instruction combiner logic.
static Constant * AddOne(Constant *C)
Add one to a Constant.
static Constant * getSExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1901
0 0 0 1 True if ordered and equal
Definition: InstrTypes.h:728
CallInst * CreateCall(FunctionType *FTy, Value *Callee, ArrayRef< Value *> Args=None, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:2328
std::underlying_type_t< E > Mask()
Get a bitmask with 1s in all places up to the high-order bit of E&#39;s largest value.
Definition: BitmaskEnum.h:80
This file implements a class to represent arbitrary precision integral constant values and operations...
BinaryOp_match< LHS, RHS, Instruction::Add > m_Add(const LHS &L, const RHS &R)
Definition: PatternMatch.h:840
bind_ty< WithOverflowInst > m_WithOverflowInst(WithOverflowInst *&I)
Match a with overflow intrinsic, capturing it if we match.
Definition: PatternMatch.h:621
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1915
OverflowingBinaryOp_match< LHS, RHS, Instruction::Add, OverflowingBinaryOperator::NoUnsignedWrap > m_NUWAdd(const LHS &L, const RHS &R)
bool isNullValue() const
Return true if this is the value that would be returned by getNullValue.
Definition: Constants.cpp:86
FastMathFlags getFastMathFlags() const
Convenience function for getting all the fast-math flags, which must be an operator which supports th...
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:244
bool insert(const value_type &X)
Insert a new element into the SetVector.
Definition: SetVector.h:141
apfloat_match m_APFloat(const APFloat *&Res)
Match a ConstantFP or splatted ConstantVector, binding the specified pointer to the contained APFloat...
Definition: PatternMatch.h:230
CastClass_match< OpTy, Instruction::ZExt > m_ZExt(const OpTy &Op)
Matches ZExt.
unsigned greater or equal
Definition: InstrTypes.h:749
This instruction compares its operands according to the predicate given to the constructor.
void andIRFlags(const Value *V)
Logical &#39;and&#39; of any supported wrapping, exact, and fast-math flags of V and this instruction...
MaxMin_match< FCmpInst, LHS, RHS, ofmin_pred_ty > m_OrdFMin(const LHS &L, const RHS &R)
Match an &#39;ordered&#39; floating point minimum function.
MaxMin_match< ICmpInst, LHS, RHS, smin_pred_ty > m_SMin(const LHS &L, const RHS &R)
MDNode * getMetadata(unsigned KindID) const
Get the metadata of given kind attached to this Instruction.
Definition: Instruction.h:279
class_match< ConstantInt > m_ConstantInt()
Match an arbitrary ConstantInt and ignore it.
Definition: PatternMatch.h:92
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:160
cstfp_pred_ty< is_pos_zero_fp > m_PosZeroFP()
Match a floating-point positive zero.
Definition: PatternMatch.h:581
Value * CreateSExt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1962
Value * CreateFNegFMF(Value *V, Instruction *FMFSource, const Twine &Name="")
Copy fast-math-flags from an instruction rather than using the builder&#39;s default FMF.
Definition: IRBuilder.h:1554
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:204
Value * getRHS() const
CallInst * CreateUnaryIntrinsic(Intrinsic::ID ID, Value *V, Instruction *FMFSource=nullptr, const Twine &Name="")
Create a call to intrinsic ID with 1 operand which is mangled on its type.
Definition: IRBuilder.cpp:768
static Instruction * foldSelectICmpAndAnd(Type *SelType, const ICmpInst *Cmp, Value *TVal, Value *FVal, InstCombiner::BuilderTy &Builder)
We want to turn: (select (icmp eq (and X, Y), 0), (and (lshr X, Z), 1), 1) into: zext (icmp ne i32 (a...
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power-of-2.
Definition: PatternMatch.h:460
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
Function * getDeclaration(Module *M, ID id, ArrayRef< Type *> Tys=None)
Create or insert an LLVM Function declaration for an intrinsic, and return it.
Definition: Function.cpp:1161
static BinaryOperator * CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
void SetInsertPoint(BasicBlock *TheBB)
This specifies that created instructions should be appended to the end of the specified block...
Definition: IRBuilder.h:161
Value * getOperand(unsigned i) const
Definition: User.h:169
PHINode * CreatePHI(Type *Ty, unsigned NumReservedValues, const Twine &Name="")
Definition: IRBuilder.h:2320
bool CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI, unsigned Depth=0)
Return true if we can prove that the specified FP value is never equal to -0.0.
void replaceUsesOfWith(Value *From, Value *To)
Replace uses of one Value with another.
Definition: User.cpp:21
Constant * getAggregateElement(unsigned Elt) const
For aggregates (struct/array/vector) return the constant that corresponds to the specified element if...
Definition: Constants.cpp:402
Instruction * replaceOperand(Instruction &I, unsigned OpNum, Value *V)
Replace operand of instruction and add old operand to the worklist.
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:309
SmallVector< MachineOperand, 4 > Cond
MaxMin_match< ICmpInst, LHS, RHS, umin_pred_ty, true > m_c_UMin(const LHS &L, const RHS &R)
Matches a UMin with LHS and RHS in either order.
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:67
#define P(N)
BinaryOp_match< LHS, RHS, Instruction::LShr > m_LShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:979
bool hasNUsesOrMore(unsigned N) const
Return true if this value has N users or more.
Definition: Value.cpp:146
Value * SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, const SimplifyQuery &Q)
Given operands for a SelectInst, fold the result or return null.
bool isAllOnesValue() const
Determine if all bits are set.
Definition: APInt.h:400
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
MaxMin_match< ICmpInst, LHS, RHS, umax_pred_ty > m_UMax(const LHS &L, const RHS &R)
bool hasNUses(unsigned N) const
Return true if this Value has exactly N users.
Definition: Value.cpp:142
apint_match m_APInt(const APInt *&Res)
Match a ConstantInt or splatted ConstantVector, binding the specified pointer to the contained APInt...
Definition: PatternMatch.h:213
bool isNegative() const
Definition: APFloat.h:1203
Value * CreateAShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1300
BinaryOp_match< LHS, RHS, Instruction::Add, true > m_c_Add(const LHS &L, const RHS &R)
Matches a Add with LHS and RHS in either order.
bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW=false)
Return true if the two given values are negation.
constexpr bool isPowerOf2_32(uint32_t Value)
Return true if the argument is a power of two > 0.
Definition: MathExtras.h:492
LLVM Basic Block Representation.
Definition: BasicBlock.h:58
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
BinaryOp_match< LHS, RHS, Instruction::Or > m_Or(const LHS &L, const RHS &R)
Definition: PatternMatch.h:961
Value * CreateNot(Value *V, const Twine &Name="")
Definition: IRBuilder.h:1563
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1207
CastClass_match< OpTy, Instruction::BitCast > m_BitCast(const OpTy &Op)
Matches BitCast.
signed less than
Definition: InstrTypes.h:754
This is an important base class in LLVM.
Definition: Constant.h:41
This file contains the declarations for the subclasses of Constant, which represent the different fla...
bool isSignBitCheck(ICmpInst::Predicate Pred, const APInt &RHS, bool &TrueIfSigned)
Given an exploded icmp instruction, return true if the comparison only checks the sign bit...
BinaryOp_match< LHS, RHS, Instruction::And, true > m_c_And(const LHS &L, const RHS &R)
Matches an And with LHS and RHS in either order.
static BinaryOperator * CreateNUW(BinaryOps Opc, Value *V1, Value *V2, const Twine &Name="")
Definition: InstrTypes.h:305
bool isOneValue() const
Determine if this is a value of 1.
Definition: APInt.h:415
APInt ssub_ov(const APInt &RHS, bool &Overflow) const
Definition: APInt.cpp:1967
specific_intval m_SpecificInt(APInt V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:725
cst_pred_ty< is_all_ones > m_AllOnes()
Match an integer or vector with all bits set.
Definition: PatternMatch.h:361
static APInt getOneBitSet(unsigned numBits, unsigned BitNo)
Return an APInt with exactly one bit set in the result.
Definition: APInt.h:592
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:648
Class to represent fixed width SIMD vectors.
Definition: DerivedTypes.h:557
1 0 1 1 True if unordered, greater than, or equal
Definition: InstrTypes.h:738
bool any_of(R &&range, UnaryPredicate P)
Provide wrappers to std::any_of which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1498
unsigned greater than
Definition: InstrTypes.h:748
This instruction compares its operands according to the predicate given to the constructor.
static Constant * getBinOpIdentity(unsigned Opcode, Type *Ty, bool AllowRHSConstant=false)
Return the identity constant for a binary opcode.
Definition: Constants.cpp:2569
Value * CreateNeg(Value *V, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1526
0 0 1 0 True if ordered and greater than
Definition: InstrTypes.h:729
op_range operands()
Definition: User.h:242
MaxMin_match< ICmpInst, LHS, RHS, smax_pred_ty, true > m_c_SMax(const LHS &L, const RHS &R)
Matches an SMax with LHS and RHS in either order.
CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF, bool Ordered=false)
Return the canonical comparison predicate for the specified minimum/maximum flavor.
static Constant * getICmp(unsigned short pred, Constant *LHS, Constant *RHS, bool OnlyIfReduced=false)
get* - Return some common constants without having to specify the full Instruction::OPCODE identifier...
Definition: Constants.cpp:2293
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:84
Value * CreateIsNotNull(Value *Arg, const Twine &Name="")
Return an i1 value testing if Arg is not null.
Definition: IRBuilder.h:2464
Class to represent integer types.
Definition: DerivedTypes.h:40
Value * CreateXor(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1372
constexpr unsigned BitWidth
Definition: BitmaskEnum.h:147
const Value * getCondition() const
assume Assume Builder
1 1 0 0 True if unordered or less than
Definition: InstrTypes.h:739
bool isCast() const
Definition: Instruction.h:168
TwoOps_match< Val_t, Idx_t, Instruction::ExtractElement > m_ExtractElt(const Val_t &Val, const Idx_t &Idx)
Matches ExtractElementInst.
C setMetadata(LLVMContext::MD_range, MDNode::get(Context, LowAndHigh))
void swapProfMetadata()
If the instruction has "branch_weights" MD_prof metadata and the MDNode has three operands (including...
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
LLVM_READONLY APFloat maxnum(const APFloat &A, const APFloat &B)
Implements IEEE maxNum semantics.
Definition: APFloat.h:1294
Value * CreateICmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2274
deferredval_ty< Value > m_Deferred(Value *const &V)
A commutative-friendly version of m_Specific().
Definition: PatternMatch.h:661
Type * getWithNewBitWidth(unsigned NewBitWidth) const
Given an integer or vector type, change the lane bitwidth to NewBitwidth, whilst keeping the old numb...
Definition: DerivedTypes.h:708
CastClass_match< OpTy, Instruction::SExt > m_SExt(const OpTy &Op)
Matches SExt.
Intrinsic::ID getIntrinsicID() const
Return the intrinsic ID of this intrinsic.
Definition: IntrinsicInst.h:51
Floating point maxnum.
MaxMin_match< ICmpInst, LHS, RHS, umax_pred_ty, true > m_c_UMax(const LHS &L, const RHS &R)
Matches a UMax with LHS and RHS in either order.
Value * CreateICmpSGE(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2192
static Value * createMinMax(InstCombiner::BuilderTy &Builder, SelectPatternFlavor SPF, Value *A, Value *B)
1 1 0 1 True if unordered, less than, or equal
Definition: InstrTypes.h:740
static Value * foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal, Value *FalseVal, InstCombiner::BuilderTy &Builder)
We want to turn: (select (icmp eq (and X, C1), 0), Y, (or Y, C2)) into: (or (shl (and X...
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:302
unsigned getNumOperands() const
Definition: User.h:191
static Instruction * foldSetClearBits(SelectInst &Sel, InstCombiner::BuilderTy &Builder)
Canonicalize a set or clear of a masked set of constant bits to select-of-constants form...
SelectPatternFlavor Flavor
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type...
Definition: Type.cpp:137
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:883
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:251
SelectPatternFlavor
Specific patterns of select instructions we can match.
Instruction * user_back()
Specialize the methods defined in Value, as we know that an instruction can only be used by other ins...
Definition: Instruction.h:91
Provides information about what library functions are available for the current target.
Value * CreateSelect(Value *C, Value *True, Value *False, const Twine &Name="", Instruction *MDFrom=nullptr)
Definition: IRBuilder.cpp:920
Value * CreateVectorSplat(unsigned NumElts, Value *V, const Twine &Name="")
Return a vector value that contains.
Definition: IRBuilder.cpp:1000
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
static Constant * getTrunc(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1887
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:786
pred_range predecessors(BasicBlock *BB)
Definition: CFG.h:125
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1315
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:742
bool isCommutative() const
Return true if the instruction is commutative:
Definition: Instruction.h:535
Instruction * visitSelectInst(SelectInst &SI)
void setPredicate(Predicate P)
Set the predicate for this instruction to the specified value.
Definition: InstrTypes.h:805
OverflowingBinaryOp_match< LHS, RHS, Instruction::Add, OverflowingBinaryOperator::NoSignedWrap > m_NSWAdd(const LHS &L, const RHS &R)
void setOperand(unsigned i, Value *Val)
Definition: User.h:174
unsigned logBase2() const
Definition: APInt.h:1808
BinaryOp_match< cst_pred_ty< is_zero_int >, ValTy, Instruction::Sub > m_Neg(const ValTy &V)
Matches a &#39;Neg&#39; as &#39;sub 0, V&#39;.
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:962
bool isIntPredicate() const
Definition: InstrTypes.h:820
Base class of all SIMD vector types.
Definition: DerivedTypes.h:390
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:68
Class for arbitrary precision integers.
Definition: APInt.h:69
bool ule(const APInt &RHS) const
Unsigned less or equal comparison.
Definition: APInt.h:1245
static Value * canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal, InstCombiner::BuilderTy &Builder)
bool isPowerOf2() const
Check if this APInt&#39;s value is a power of two greater than zero.
Definition: APInt.h:468
static BinaryOperator * Create(BinaryOps Op, Value *S1, Value *S2, const Twine &Name=Twine(), Instruction *InsertBefore=nullptr)
Construct a binary instruction, given the opcode and the two operands.
bool sge(const APInt &RHS) const
Signed greater or equal comparison.
Definition: APInt.h:1331
iterator_range< user_iterator > users()
Definition: Value.h:418
unsigned less or equal
Definition: InstrTypes.h:751
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1780
const Value * getFalseValue() const
static APInt getSelectFoldableConstant(BinaryOperator *I)
For the same transformation as the previous function, return the identity constant that goes into the...
static Constant * getNeg(Constant *C, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2462
static CastInst * Create(Instruction::CastOps, Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Provides a way to construct any of the CastInst subclasses using an opcode instead of the subclass&#39;s ...
bool ugt(const APInt &RHS) const
Unsigned greater than comparison.
Definition: APInt.h:1277
Predicate getPredicate() const
Return the predicate for this instruction.
Definition: InstrTypes.h:802
static cl::opt< bool > NeedAnd("extract-needand", cl::init(true), cl::Hidden, cl::desc("Require & in extract patterns"))
FNeg_match< OpTy > m_FNeg(const OpTy &X)
Match &#39;fneg X&#39; as &#39;fsub -0.0, X&#39;.
Definition: PatternMatch.h:895
static Value * canonicalizeSaturatedSubtract(const ICmpInst *ICI, const Value *TrueVal, const Value *FalseVal, InstCombiner::BuilderTy &Builder)
Transform patterns such as (a > b) ? a - b : 0 into usub.sat(a, b).
unsigned getIntegerBitWidth() const
Definition: DerivedTypes.h:102
static bool isMinOrMax(SelectPatternFlavor SPF)
When implementing this min/max pattern as fcmp; select, does the fcmp have to be ordered?
static bool isUnordered(Predicate predicate)
Determine if the predicate is an unordered operation.
Value * CreateOr(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1346
MaxMin_match< ICmpInst, LHS, RHS, smin_pred_ty, true > m_c_SMin(const LHS &L, const RHS &R)
Matches an SMin with LHS and RHS in either order.
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:270
1 0 1 0 True if unordered or greater than
Definition: InstrTypes.h:737
unsigned getNumElements() const
Get the number of elements in this vector.
Definition: DerivedTypes.h:426
bool isEquality() const
Return true if this predicate is either EQ or NE.
#define I(x, y, z)
Definition: MD5.cpp:59
llvm::Optional< std::pair< CmpInst::Predicate, Constant * > > getFlippedStrictnessPredicateAndConstant(CmpInst::Predicate Pred, Constant *C)
APFloat abs(APFloat X)
Returns the absolute value of the argument.
Definition: APFloat.h:1269
MaxMin_match< ICmpInst, LHS, RHS, smax_pred_ty > m_SMax(const LHS &L, const RHS &R)
void swapValues()
Swap the true and false values of the select instruction.
class_match< BasicBlock > m_BasicBlock()
Match an arbitrary basic block value and ignore it.
Definition: PatternMatch.h:103
Signed minimum.
0 0 1 1 True if ordered and greater than or equal
Definition: InstrTypes.h:730
CallInst * CreateBinaryIntrinsic(Intrinsic::ID ID, Value *LHS, Value *RHS, Instruction *FMFSource=nullptr, const Twine &Name="")
Create a call to intrinsic ID with 2 operands which is mangled on the first type. ...
Definition: IRBuilder.cpp:776
static Value * getNumElements(BasicBlock *Preheader, Value *BTC)
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1259
bool isFPOrFPVectorTy() const
Return true if this is a FP type or a vector of FP.
Definition: Type.h:186
Value * CreateFNeg(Value *V, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1544
bool isOneValue() const
Returns true if the value is one.
Definition: Constants.cpp:127
0 1 0 1 True if ordered and less than or equal
Definition: InstrTypes.h:732
Value * SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for a BinaryOperator, fold the result or return null.
static GetElementPtrInst * CreateInBounds(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Create an "inbounds" getelementptr.
Definition: Instructions.h:964
signed greater than
Definition: InstrTypes.h:752
Value * CreateICmpSLT(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2196
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static APInt getSignedMinValue(unsigned numBits)
Gets minimum signed value of APInt for a specific bit width.
Definition: APInt.h:549
MaxMin_match< FCmpInst, LHS, RHS, ofmax_pred_ty > m_OrdFMax(const LHS &L, const RHS &R)
Match an &#39;ordered&#39; floating point maximum function.
LLVM Value Representation.
Definition: Value.h:74
This file provides internal interfaces used to implement the InstCombine.
SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, Instruction::CastOps *CastOp=nullptr, unsigned Depth=0)
Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind and providing the out param...
cst_pred_ty< is_one > m_One()
Match an integer 1 or a vector with all elements equal to 1.
Definition: PatternMatch.h:429
bool bitwiseIsEqual(const APFloat &RHS) const
Definition: APFloat.h:1168
#define LLVM_FALLTHROUGH
LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
Definition: Compiler.h:280
void setFastMathFlags(FastMathFlags NewFMF)
Set the fast-math flags to be used with generated fp-math operators.
Definition: IRBuilder.h:256
void moveBefore(Instruction *MovePos)
Unlink this instruction from its current basic block and insert it into the basic block that MovePos ...
Definition: Instruction.cpp:99
Value * CreateZExtOrTrunc(Value *V, Type *DestTy, const Twine &Name="")
Create a ZExt or Trunc from the integer value V to DestTy.
Definition: IRBuilder.h:1968
match_combine_and< LTy, RTy > m_CombineAnd(const LTy &L, const RTy &R)
Combine two pattern matchers matching L && R.
Definition: PatternMatch.h:159
TwoOps_match< V1_t, V2_t, Instruction::ShuffleVector > m_Shuffle(const V1_t &v1, const V2_t &v2)
Matches ShuffleVectorInst independently of mask value.
cst_pred_ty< is_any_apint > m_AnyIntegralConstant()
Match an integer or vector with any integral constant.
Definition: PatternMatch.h:352
bool hasNoNaNs() const
Determine whether the no-NaNs flag is set.
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:431
Convenience struct for specifying and reasoning about fast-math flags.
Definition: Operator.h:160
Predicate getSwappedPredicate() const
For example, EQ->EQ, SLE->SGE, ULT->UGT, OEQ->OEQ, ULE->UGE, OLT->OGT, etc.
Definition: InstrTypes.h:842
static APInt getNullValue(unsigned numBits)
Get the &#39;0&#39; value.
Definition: APInt.h:573
cstfp_pred_ty< is_any_zero_fp > m_AnyZeroFP()
Match a floating-point negative zero or positive zero.
Definition: PatternMatch.h:572
Value * getLHS() const
LLVM_READONLY APFloat minnum(const APFloat &A, const APFloat &B)
Implements IEEE minNum semantics.
Definition: APFloat.h:1283
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:615
BinaryOp_match< ValTy, cst_pred_ty< is_all_ones >, Instruction::Xor, true > m_Not(const ValTy &V)
Matches a &#39;Not&#39; as &#39;xor V, -1&#39; or &#39;xor -1, V&#39;.
bool isNullValue() const
Determine if all bits are clear.
Definition: APInt.h:410
1 1 1 0 True if unordered or not equal
Definition: InstrTypes.h:741
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:44
const BasicBlock * getParent() const
Definition: Instruction.h:94
CmpClass_match< LHS, RHS, ICmpInst, ICmpInst::Predicate > m_ICmp(ICmpInst::Predicate &Pred, const LHS &L, const RHS &R)
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
bool is_contained(R &&Range, const E &Element)
Wrapper function around std::find to detect if an element exists in a container.
Definition: STLExtras.h:1549