LLVM  9.0.0svn
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  // The select condition must be an equality compare with a constant operand.
61  Value *X;
62  Constant *C;
63  CmpInst::Predicate Pred;
64  if (!match(Sel.getCondition(), m_Cmp(Pred, m_Value(X), m_Constant(C))))
65  return nullptr;
66 
67  bool IsEq;
68  if (ICmpInst::isEquality(Pred))
69  IsEq = Pred == ICmpInst::ICMP_EQ;
70  else if (Pred == FCmpInst::FCMP_OEQ)
71  IsEq = true;
72  else if (Pred == FCmpInst::FCMP_UNE)
73  IsEq = false;
74  else
75  return nullptr;
76 
77  // A select operand must be a binop.
78  BinaryOperator *BO;
79  if (!match(Sel.getOperand(IsEq ? 1 : 2), m_BinOp(BO)))
80  return nullptr;
81 
82  // The compare constant must be the identity constant for that binop.
83  // If this a floating-point compare with 0.0, any zero constant will do.
84  Type *Ty = BO->getType();
85  Constant *IdC = ConstantExpr::getBinOpIdentity(BO->getOpcode(), Ty, true);
86  if (IdC != C) {
87  if (!IdC || !CmpInst::isFPPredicate(Pred))
88  return nullptr;
89  if (!match(IdC, m_AnyZeroFP()) || !match(C, m_AnyZeroFP()))
90  return nullptr;
91  }
92 
93  // Last, match the compare variable operand with a binop operand.
94  Value *Y;
95  if (!BO->isCommutative() && !match(BO, m_BinOp(m_Value(Y), m_Specific(X))))
96  return nullptr;
97  if (!match(BO, m_c_BinOp(m_Value(Y), m_Specific(X))))
98  return nullptr;
99 
100  // +0.0 compares equal to -0.0, and so it does not behave as required for this
101  // transform. Bail out if we can not exclude that possibility.
102  if (isa<FPMathOperator>(BO))
103  if (!BO->hasNoSignedZeros() && !CannotBeNegativeZero(Y, &TLI))
104  return nullptr;
105 
106  // BO = binop Y, X
107  // S = { select (cmp eq X, C), BO, ? } or { select (cmp ne X, C), ?, BO }
108  // =>
109  // S = { select (cmp eq X, C), Y, ? } or { select (cmp ne X, C), ?, Y }
110  Sel.setOperand(IsEq ? 1 : 2, Y);
111  return &Sel;
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.
124  InstCombiner::BuilderTy &Builder) {
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 (CondTy->isVectorTy()) {
305  if (!FIOpndTy->isVectorTy())
306  return nullptr;
307  if (CondTy->getVectorNumElements() != FIOpndTy->getVectorNumElements())
308  return nullptr;
309 
310  // TODO: If the backend knew how to deal with casts better, we could
311  // remove this limitation. For now, there's too much potential to create
312  // worse codegen by promoting the select ahead of size-altering casts
313  // (PR28160).
314  //
315  // Note that ValueTracking's matchSelectPattern() looks through casts
316  // without checking 'hasOneUse' when it matches min/max patterns, so this
317  // transform may end up happening anyway.
318  if (TI->getOpcode() != Instruction::BitCast &&
319  (!TI->hasOneUse() || !FI->hasOneUse()))
320  return nullptr;
321  } else if (!TI->hasOneUse() || !FI->hasOneUse()) {
322  // TODO: The one-use restrictions for a scalar select could be eased if
323  // the fold of a select in visitLoadInst() was enhanced to match a pattern
324  // that includes a cast.
325  return nullptr;
326  }
327 
328  // Fold this by inserting a select from the input values.
329  Value *NewSI =
330  Builder.CreateSelect(Cond, TI->getOperand(0), FI->getOperand(0),
331  SI.getName() + ".v", &SI);
332  return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
333  TI->getType());
334  }
335 
336  // Cond ? -X : -Y --> -(Cond ? X : Y)
337  Value *X, *Y;
338  if (match(TI, m_FNeg(m_Value(X))) && match(FI, m_FNeg(m_Value(Y))) &&
339  (TI->hasOneUse() || FI->hasOneUse())) {
340  Value *NewSel = Builder.CreateSelect(Cond, X, Y, SI.getName() + ".v", &SI);
341  // TODO: Remove the hack for the binop form when the unary op is optimized
342  // properly with all IR passes.
343  if (TI->getOpcode() != Instruction::FNeg)
344  return BinaryOperator::CreateFNegFMF(NewSel, cast<BinaryOperator>(TI));
345  return UnaryOperator::CreateFNeg(NewSel);
346  }
347 
348  // Only handle binary operators (including two-operand getelementptr) with
349  // one-use here. As with the cast case above, it may be possible to relax the
350  // one-use constraint, but that needs be examined carefully since it may not
351  // reduce the total number of instructions.
352  if (TI->getNumOperands() != 2 || FI->getNumOperands() != 2 ||
353  (!isa<BinaryOperator>(TI) && !isa<GetElementPtrInst>(TI)) ||
354  !TI->hasOneUse() || !FI->hasOneUse())
355  return nullptr;
356 
357  // Figure out if the operations have any operands in common.
358  Value *MatchOp, *OtherOpT, *OtherOpF;
359  bool MatchIsOpZero;
360  if (TI->getOperand(0) == FI->getOperand(0)) {
361  MatchOp = TI->getOperand(0);
362  OtherOpT = TI->getOperand(1);
363  OtherOpF = FI->getOperand(1);
364  MatchIsOpZero = true;
365  } else if (TI->getOperand(1) == FI->getOperand(1)) {
366  MatchOp = TI->getOperand(1);
367  OtherOpT = TI->getOperand(0);
368  OtherOpF = FI->getOperand(0);
369  MatchIsOpZero = false;
370  } else if (!TI->isCommutative()) {
371  return nullptr;
372  } else if (TI->getOperand(0) == FI->getOperand(1)) {
373  MatchOp = TI->getOperand(0);
374  OtherOpT = TI->getOperand(1);
375  OtherOpF = FI->getOperand(0);
376  MatchIsOpZero = true;
377  } else if (TI->getOperand(1) == FI->getOperand(0)) {
378  MatchOp = TI->getOperand(1);
379  OtherOpT = TI->getOperand(0);
380  OtherOpF = FI->getOperand(1);
381  MatchIsOpZero = true;
382  } else {
383  return nullptr;
384  }
385 
386  // If the select condition is a vector, the operands of the original select's
387  // operands also must be vectors. This may not be the case for getelementptr
388  // for example.
389  if (CondTy->isVectorTy() && (!OtherOpT->getType()->isVectorTy() ||
390  !OtherOpF->getType()->isVectorTy()))
391  return nullptr;
392 
393  // If we reach here, they do have operations in common.
394  Value *NewSI = Builder.CreateSelect(Cond, OtherOpT, OtherOpF,
395  SI.getName() + ".v", &SI);
396  Value *Op0 = MatchIsOpZero ? MatchOp : NewSI;
397  Value *Op1 = MatchIsOpZero ? NewSI : MatchOp;
398  if (auto *BO = dyn_cast<BinaryOperator>(TI)) {
399  BinaryOperator *NewBO = BinaryOperator::Create(BO->getOpcode(), Op0, Op1);
400  NewBO->copyIRFlags(TI);
401  NewBO->andIRFlags(FI);
402  return NewBO;
403  }
404  if (auto *TGEP = dyn_cast<GetElementPtrInst>(TI)) {
405  auto *FGEP = cast<GetElementPtrInst>(FI);
406  Type *ElementType = TGEP->getResultElementType();
407  return TGEP->isInBounds() && FGEP->isInBounds()
408  ? GetElementPtrInst::CreateInBounds(ElementType, Op0, {Op1})
409  : GetElementPtrInst::Create(ElementType, Op0, {Op1});
410  }
411  llvm_unreachable("Expected BinaryOperator or GEP");
412  return nullptr;
413 }
414 
415 static bool isSelect01(const APInt &C1I, const APInt &C2I) {
416  if (!C1I.isNullValue() && !C2I.isNullValue()) // One side must be zero.
417  return false;
418  return C1I.isOneValue() || C1I.isAllOnesValue() ||
419  C2I.isOneValue() || C2I.isAllOnesValue();
420 }
421 
422 /// Try to fold the select into one of the operands to allow further
423 /// optimization.
424 Instruction *InstCombiner::foldSelectIntoOp(SelectInst &SI, Value *TrueVal,
425  Value *FalseVal) {
426  // See the comment above GetSelectFoldableOperands for a description of the
427  // transformation we are doing here.
428  if (auto *TVI = dyn_cast<BinaryOperator>(TrueVal)) {
429  if (TVI->hasOneUse() && !isa<Constant>(FalseVal)) {
430  if (unsigned SFO = getSelectFoldableOperands(TVI)) {
431  unsigned OpToFold = 0;
432  if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
433  OpToFold = 1;
434  } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
435  OpToFold = 2;
436  }
437 
438  if (OpToFold) {
440  Value *OOp = TVI->getOperand(2-OpToFold);
441  // Avoid creating select between 2 constants unless it's selecting
442  // between 0, 1 and -1.
443  const APInt *OOpC;
444  bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
445  if (!isa<Constant>(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) {
446  Value *C = ConstantInt::get(OOp->getType(), CI);
447  Value *NewSel = Builder.CreateSelect(SI.getCondition(), OOp, C);
448  NewSel->takeName(TVI);
449  BinaryOperator *BO = BinaryOperator::Create(TVI->getOpcode(),
450  FalseVal, NewSel);
451  BO->copyIRFlags(TVI);
452  return BO;
453  }
454  }
455  }
456  }
457  }
458 
459  if (auto *FVI = dyn_cast<BinaryOperator>(FalseVal)) {
460  if (FVI->hasOneUse() && !isa<Constant>(TrueVal)) {
461  if (unsigned SFO = getSelectFoldableOperands(FVI)) {
462  unsigned OpToFold = 0;
463  if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
464  OpToFold = 1;
465  } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
466  OpToFold = 2;
467  }
468 
469  if (OpToFold) {
471  Value *OOp = FVI->getOperand(2-OpToFold);
472  // Avoid creating select between 2 constants unless it's selecting
473  // between 0, 1 and -1.
474  const APInt *OOpC;
475  bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
476  if (!isa<Constant>(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) {
477  Value *C = ConstantInt::get(OOp->getType(), CI);
478  Value *NewSel = Builder.CreateSelect(SI.getCondition(), C, OOp);
479  NewSel->takeName(FVI);
480  BinaryOperator *BO = BinaryOperator::Create(FVI->getOpcode(),
481  TrueVal, NewSel);
482  BO->copyIRFlags(FVI);
483  return BO;
484  }
485  }
486  }
487  }
488  }
489 
490  return nullptr;
491 }
492 
493 /// We want to turn:
494 /// (select (icmp eq (and X, Y), 0), (and (lshr X, Z), 1), 1)
495 /// into:
496 /// zext (icmp ne i32 (and X, (or Y, (shl 1, Z))), 0)
497 /// Note:
498 /// Z may be 0 if lshr is missing.
499 /// Worst-case scenario is that we will replace 5 instructions with 5 different
500 /// instructions, but we got rid of select.
501 static Instruction *foldSelectICmpAndAnd(Type *SelType, const ICmpInst *Cmp,
502  Value *TVal, Value *FVal,
503  InstCombiner::BuilderTy &Builder) {
504  if (!(Cmp->hasOneUse() && Cmp->getOperand(0)->hasOneUse() &&
505  Cmp->getPredicate() == ICmpInst::ICMP_EQ &&
506  match(Cmp->getOperand(1), m_Zero()) && match(FVal, m_One())))
507  return nullptr;
508 
509  // The TrueVal has general form of: and %B, 1
510  Value *B;
511  if (!match(TVal, m_OneUse(m_And(m_Value(B), m_One()))))
512  return nullptr;
513 
514  // Where %B may be optionally shifted: lshr %X, %Z.
515  Value *X, *Z;
516  const bool HasShift = match(B, m_OneUse(m_LShr(m_Value(X), m_Value(Z))));
517  if (!HasShift)
518  X = B;
519 
520  Value *Y;
521  if (!match(Cmp->getOperand(0), m_c_And(m_Specific(X), m_Value(Y))))
522  return nullptr;
523 
524  // ((X & Y) == 0) ? ((X >> Z) & 1) : 1 --> (X & (Y | (1 << Z))) != 0
525  // ((X & Y) == 0) ? (X & 1) : 1 --> (X & (Y | 1)) != 0
526  Constant *One = ConstantInt::get(SelType, 1);
527  Value *MaskB = HasShift ? Builder.CreateShl(One, Z) : One;
528  Value *FullMask = Builder.CreateOr(Y, MaskB);
529  Value *MaskedX = Builder.CreateAnd(X, FullMask);
530  Value *ICmpNeZero = Builder.CreateIsNotNull(MaskedX);
531  return new ZExtInst(ICmpNeZero, SelType);
532 }
533 
534 /// We want to turn:
535 /// (select (icmp eq (and X, C1), 0), Y, (or Y, C2))
536 /// into:
537 /// (or (shl (and X, C1), C3), Y)
538 /// iff:
539 /// C1 and C2 are both powers of 2
540 /// where:
541 /// C3 = Log(C2) - Log(C1)
542 ///
543 /// This transform handles cases where:
544 /// 1. The icmp predicate is inverted
545 /// 2. The select operands are reversed
546 /// 3. The magnitude of C2 and C1 are flipped
547 static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal,
548  Value *FalseVal,
549  InstCombiner::BuilderTy &Builder) {
550  // Only handle integer compares. Also, if this is a vector select, we need a
551  // vector compare.
552  if (!TrueVal->getType()->isIntOrIntVectorTy() ||
553  TrueVal->getType()->isVectorTy() != IC->getType()->isVectorTy())
554  return nullptr;
555 
556  Value *CmpLHS = IC->getOperand(0);
557  Value *CmpRHS = IC->getOperand(1);
558 
559  Value *V;
560  unsigned C1Log;
561  bool IsEqualZero;
562  bool NeedAnd = false;
563  if (IC->isEquality()) {
564  if (!match(CmpRHS, m_Zero()))
565  return nullptr;
566 
567  const APInt *C1;
568  if (!match(CmpLHS, m_And(m_Value(), m_Power2(C1))))
569  return nullptr;
570 
571  V = CmpLHS;
572  C1Log = C1->logBase2();
573  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ;
574  } else if (IC->getPredicate() == ICmpInst::ICMP_SLT ||
575  IC->getPredicate() == ICmpInst::ICMP_SGT) {
576  // We also need to recognize (icmp slt (trunc (X)), 0) and
577  // (icmp sgt (trunc (X)), -1).
578  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_SGT;
579  if ((IsEqualZero && !match(CmpRHS, m_AllOnes())) ||
580  (!IsEqualZero && !match(CmpRHS, m_Zero())))
581  return nullptr;
582 
583  if (!match(CmpLHS, m_OneUse(m_Trunc(m_Value(V)))))
584  return nullptr;
585 
586  C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1;
587  NeedAnd = true;
588  } else {
589  return nullptr;
590  }
591 
592  const APInt *C2;
593  bool OrOnTrueVal = false;
594  bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)));
595  if (!OrOnFalseVal)
596  OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2)));
597 
598  if (!OrOnFalseVal && !OrOnTrueVal)
599  return nullptr;
600 
601  Value *Y = OrOnFalseVal ? TrueVal : FalseVal;
602 
603  unsigned C2Log = C2->logBase2();
604 
605  bool NeedXor = (!IsEqualZero && OrOnFalseVal) || (IsEqualZero && OrOnTrueVal);
606  bool NeedShift = C1Log != C2Log;
607  bool NeedZExtTrunc = Y->getType()->getScalarSizeInBits() !=
609 
610  // Make sure we don't create more instructions than we save.
611  Value *Or = OrOnFalseVal ? FalseVal : TrueVal;
612  if ((NeedShift + NeedXor + NeedZExtTrunc) >
613  (IC->hasOneUse() + Or->hasOneUse()))
614  return nullptr;
615 
616  if (NeedAnd) {
617  // Insert the AND instruction on the input to the truncate.
619  V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), C1));
620  }
621 
622  if (C2Log > C1Log) {
623  V = Builder.CreateZExtOrTrunc(V, Y->getType());
624  V = Builder.CreateShl(V, C2Log - C1Log);
625  } else if (C1Log > C2Log) {
626  V = Builder.CreateLShr(V, C1Log - C2Log);
627  V = Builder.CreateZExtOrTrunc(V, Y->getType());
628  } else
629  V = Builder.CreateZExtOrTrunc(V, Y->getType());
630 
631  if (NeedXor)
632  V = Builder.CreateXor(V, *C2);
633 
634  return Builder.CreateOr(V, Y);
635 }
636 
637 /// Transform patterns such as (a > b) ? a - b : 0 into usub.sat(a, b).
638 /// There are 8 commuted/swapped variants of this pattern.
639 /// TODO: Also support a - UMIN(a,b) patterns.
641  const Value *TrueVal,
642  const Value *FalseVal,
643  InstCombiner::BuilderTy &Builder) {
644  ICmpInst::Predicate Pred = ICI->getPredicate();
645  if (!ICmpInst::isUnsigned(Pred))
646  return nullptr;
647 
648  // (b > a) ? 0 : a - b -> (b <= a) ? a - b : 0
649  if (match(TrueVal, m_Zero())) {
650  Pred = ICmpInst::getInversePredicate(Pred);
651  std::swap(TrueVal, FalseVal);
652  }
653  if (!match(FalseVal, m_Zero()))
654  return nullptr;
655 
656  Value *A = ICI->getOperand(0);
657  Value *B = ICI->getOperand(1);
658  if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_ULT) {
659  // (b < a) ? a - b : 0 -> (a > b) ? a - b : 0
660  std::swap(A, B);
661  Pred = ICmpInst::getSwappedPredicate(Pred);
662  }
663 
664  assert((Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_UGT) &&
665  "Unexpected isUnsigned predicate!");
666 
667  // Account for swapped form of subtraction: ((a > b) ? b - a : 0).
668  bool IsNegative = false;
669  if (match(TrueVal, m_Sub(m_Specific(B), m_Specific(A))))
670  IsNegative = true;
671  else if (!match(TrueVal, m_Sub(m_Specific(A), m_Specific(B))))
672  return nullptr;
673 
674  // If sub is used anywhere else, we wouldn't be able to eliminate it
675  // afterwards.
676  if (!TrueVal->hasOneUse())
677  return nullptr;
678 
679  // (a > b) ? a - b : 0 -> usub.sat(a, b)
680  // (a > b) ? b - a : 0 -> -usub.sat(a, b)
681  Value *Result = Builder.CreateBinaryIntrinsic(Intrinsic::usub_sat, A, B);
682  if (IsNegative)
683  Result = Builder.CreateNeg(Result);
684  return Result;
685 }
686 
687 static Value *canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal,
688  InstCombiner::BuilderTy &Builder) {
689  if (!Cmp->hasOneUse())
690  return nullptr;
691 
692  // Match unsigned saturated add with constant.
693  Value *Cmp0 = Cmp->getOperand(0);
694  Value *Cmp1 = Cmp->getOperand(1);
695  ICmpInst::Predicate Pred = Cmp->getPredicate();
696  Value *X;
697  const APInt *C, *CmpC;
698  if (Pred == ICmpInst::ICMP_ULT &&
699  match(TVal, m_Add(m_Value(X), m_APInt(C))) && X == Cmp0 &&
700  match(FVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) && *CmpC == ~*C) {
701  // (X u< ~C) ? (X + C) : -1 --> uadd.sat(X, C)
702  return Builder.CreateBinaryIntrinsic(
703  Intrinsic::uadd_sat, X, ConstantInt::get(X->getType(), *C));
704  }
705 
706  // Match unsigned saturated add of 2 variables with an unnecessary 'not'.
707  // There are 8 commuted variants.
708  // Canonicalize -1 (saturated result) to true value of the select. Just
709  // swapping the compare operands is legal, because the selected value is the
710  // same in case of equality, so we can interchange u< and u<=.
711  if (match(FVal, m_AllOnes())) {
712  std::swap(TVal, FVal);
713  std::swap(Cmp0, Cmp1);
714  }
715  if (!match(TVal, m_AllOnes()))
716  return nullptr;
717 
718  // Canonicalize predicate to 'ULT'.
719  if (Pred == ICmpInst::ICMP_UGT) {
720  Pred = ICmpInst::ICMP_ULT;
721  std::swap(Cmp0, Cmp1);
722  }
723  if (Pred != ICmpInst::ICMP_ULT)
724  return nullptr;
725 
726  // Match unsigned saturated add of 2 variables with an unnecessary 'not'.
727  Value *Y;
728  if (match(Cmp0, m_Not(m_Value(X))) &&
729  match(FVal, m_c_Add(m_Specific(X), m_Value(Y))) && Y == Cmp1) {
730  // (~X u< Y) ? -1 : (X + Y) --> uadd.sat(X, Y)
731  // (~X u< Y) ? -1 : (Y + X) --> uadd.sat(X, Y)
732  return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, X, Y);
733  }
734  // The 'not' op may be included in the sum but not the compare.
735  X = Cmp0;
736  Y = Cmp1;
737  if (match(FVal, m_c_Add(m_Not(m_Specific(X)), m_Specific(Y)))) {
738  // (X u< Y) ? -1 : (~X + Y) --> uadd.sat(~X, Y)
739  // (X u< Y) ? -1 : (Y + ~X) --> uadd.sat(Y, ~X)
740  BinaryOperator *BO = cast<BinaryOperator>(FVal);
741  return Builder.CreateBinaryIntrinsic(
742  Intrinsic::uadd_sat, BO->getOperand(0), BO->getOperand(1));
743  }
744 
745  return nullptr;
746 }
747 
748 /// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single
749 /// call to cttz/ctlz with flag 'is_zero_undef' cleared.
750 ///
751 /// For example, we can fold the following code sequence:
752 /// \code
753 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
754 /// %1 = icmp ne i32 %x, 0
755 /// %2 = select i1 %1, i32 %0, i32 32
756 /// \code
757 ///
758 /// into:
759 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
760 static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
761  InstCombiner::BuilderTy &Builder) {
762  ICmpInst::Predicate Pred = ICI->getPredicate();
763  Value *CmpLHS = ICI->getOperand(0);
764  Value *CmpRHS = ICI->getOperand(1);
765 
766  // Check if the condition value compares a value for equality against zero.
767  if (!ICI->isEquality() || !match(CmpRHS, m_Zero()))
768  return nullptr;
769 
770  Value *Count = FalseVal;
771  Value *ValueOnZero = TrueVal;
772  if (Pred == ICmpInst::ICMP_NE)
773  std::swap(Count, ValueOnZero);
774 
775  // Skip zero extend/truncate.
776  Value *V = nullptr;
777  if (match(Count, m_ZExt(m_Value(V))) ||
778  match(Count, m_Trunc(m_Value(V))))
779  Count = V;
780 
781  // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
782  // input to the cttz/ctlz is used as LHS for the compare instruction.
783  if (!match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) &&
784  !match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS))))
785  return nullptr;
786 
787  IntrinsicInst *II = cast<IntrinsicInst>(Count);
788 
789  // Check if the value propagated on zero is a constant number equal to the
790  // sizeof in bits of 'Count'.
791  unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits();
792  if (match(ValueOnZero, m_SpecificInt(SizeOfInBits))) {
793  // Explicitly clear the 'undef_on_zero' flag.
794  IntrinsicInst *NewI = cast<IntrinsicInst>(II->clone());
796  Builder.Insert(NewI);
797  return Builder.CreateZExtOrTrunc(NewI, ValueOnZero->getType());
798  }
799 
800  // If the ValueOnZero is not the bitwidth, we can at least make use of the
801  // fact that the cttz/ctlz result will not be used if the input is zero, so
802  // it's okay to relax it to undef for that case.
803  if (II->hasOneUse() && !match(II->getArgOperand(1), m_One()))
805 
806  return nullptr;
807 }
808 
809 /// Return true if we find and adjust an icmp+select pattern where the compare
810 /// is with a constant that can be incremented or decremented to match the
811 /// minimum or maximum idiom.
812 static bool adjustMinMax(SelectInst &Sel, ICmpInst &Cmp) {
813  ICmpInst::Predicate Pred = Cmp.getPredicate();
814  Value *CmpLHS = Cmp.getOperand(0);
815  Value *CmpRHS = Cmp.getOperand(1);
816  Value *TrueVal = Sel.getTrueValue();
817  Value *FalseVal = Sel.getFalseValue();
818 
819  // We may move or edit the compare, so make sure the select is the only user.
820  const APInt *CmpC;
821  if (!Cmp.hasOneUse() || !match(CmpRHS, m_APInt(CmpC)))
822  return false;
823 
824  // These transforms only work for selects of integers or vector selects of
825  // integer vectors.
826  Type *SelTy = Sel.getType();
827  auto *SelEltTy = dyn_cast<IntegerType>(SelTy->getScalarType());
828  if (!SelEltTy || SelTy->isVectorTy() != Cmp.getType()->isVectorTy())
829  return false;
830 
831  Constant *AdjustedRHS;
832  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT)
833  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC + 1);
834  else if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT)
835  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC - 1);
836  else
837  return false;
838 
839  // X > C ? X : C+1 --> X < C+1 ? C+1 : X
840  // X < C ? X : C-1 --> X > C-1 ? C-1 : X
841  if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
842  (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
843  ; // Nothing to do here. Values match without any sign/zero extension.
844  }
845  // Types do not match. Instead of calculating this with mixed types, promote
846  // all to the larger type. This enables scalar evolution to analyze this
847  // expression.
848  else if (CmpRHS->getType()->getScalarSizeInBits() < SelEltTy->getBitWidth()) {
849  Constant *SextRHS = ConstantExpr::getSExt(AdjustedRHS, SelTy);
850 
851  // X = sext x; x >s c ? X : C+1 --> X = sext x; X <s C+1 ? C+1 : X
852  // X = sext x; x <s c ? X : C-1 --> X = sext x; X >s C-1 ? C-1 : X
853  // X = sext x; x >u c ? X : C+1 --> X = sext x; X <u C+1 ? C+1 : X
854  // X = sext x; x <u c ? X : C-1 --> X = sext x; X >u C-1 ? C-1 : X
855  if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) && SextRHS == FalseVal) {
856  CmpLHS = TrueVal;
857  AdjustedRHS = SextRHS;
858  } else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) &&
859  SextRHS == TrueVal) {
860  CmpLHS = FalseVal;
861  AdjustedRHS = SextRHS;
862  } else if (Cmp.isUnsigned()) {
863  Constant *ZextRHS = ConstantExpr::getZExt(AdjustedRHS, SelTy);
864  // X = zext x; x >u c ? X : C+1 --> X = zext x; X <u C+1 ? C+1 : X
865  // X = zext x; x <u c ? X : C-1 --> X = zext x; X >u C-1 ? C-1 : X
866  // zext + signed compare cannot be changed:
867  // 0xff <s 0x00, but 0x00ff >s 0x0000
868  if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) && ZextRHS == FalseVal) {
869  CmpLHS = TrueVal;
870  AdjustedRHS = ZextRHS;
871  } else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) &&
872  ZextRHS == TrueVal) {
873  CmpLHS = FalseVal;
874  AdjustedRHS = ZextRHS;
875  } else {
876  return false;
877  }
878  } else {
879  return false;
880  }
881  } else {
882  return false;
883  }
884 
885  Pred = ICmpInst::getSwappedPredicate(Pred);
886  CmpRHS = AdjustedRHS;
887  std::swap(FalseVal, TrueVal);
888  Cmp.setPredicate(Pred);
889  Cmp.setOperand(0, CmpLHS);
890  Cmp.setOperand(1, CmpRHS);
891  Sel.setOperand(1, TrueVal);
892  Sel.setOperand(2, FalseVal);
893  Sel.swapProfMetadata();
894 
895  // Move the compare instruction right before the select instruction. Otherwise
896  // the sext/zext value may be defined after the compare instruction uses it.
897  Cmp.moveBefore(&Sel);
898 
899  return true;
900 }
901 
902 /// If this is an integer min/max (icmp + select) with a constant operand,
903 /// create the canonical icmp for the min/max operation and canonicalize the
904 /// constant to the 'false' operand of the select:
905 /// select (icmp Pred X, C1), C2, X --> select (icmp Pred' X, C2), X, C2
906 /// Note: if C1 != C2, this will change the icmp constant to the existing
907 /// constant operand of the select.
908 static Instruction *
909 canonicalizeMinMaxWithConstant(SelectInst &Sel, ICmpInst &Cmp,
910  InstCombiner::BuilderTy &Builder) {
911  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
912  return nullptr;
913 
914  // Canonicalize the compare predicate based on whether we have min or max.
915  Value *LHS, *RHS;
916  SelectPatternResult SPR = matchSelectPattern(&Sel, LHS, RHS);
918  return nullptr;
919 
920  // Is this already canonical?
921  ICmpInst::Predicate CanonicalPred = getMinMaxPred(SPR.Flavor);
922  if (Cmp.getOperand(0) == LHS && Cmp.getOperand(1) == RHS &&
923  Cmp.getPredicate() == CanonicalPred)
924  return nullptr;
925 
926  // Create the canonical compare and plug it into the select.
927  Sel.setCondition(Builder.CreateICmp(CanonicalPred, LHS, RHS));
928 
929  // If the select operands did not change, we're done.
930  if (Sel.getTrueValue() == LHS && Sel.getFalseValue() == RHS)
931  return &Sel;
932 
933  // If we are swapping the select operands, swap the metadata too.
934  assert(Sel.getTrueValue() == RHS && Sel.getFalseValue() == LHS &&
935  "Unexpected results from matchSelectPattern");
936  Sel.setTrueValue(LHS);
937  Sel.setFalseValue(RHS);
938  Sel.swapProfMetadata();
939  return &Sel;
940 }
941 
942 /// There are many select variants for each of ABS/NABS.
943 /// In matchSelectPattern(), there are different compare constants, compare
944 /// predicates/operands and select operands.
945 /// In isKnownNegation(), there are different formats of negated operands.
946 /// Canonicalize all these variants to 1 pattern.
947 /// This makes CSE more likely.
948 static Instruction *canonicalizeAbsNabs(SelectInst &Sel, ICmpInst &Cmp,
949  InstCombiner::BuilderTy &Builder) {
950  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
951  return nullptr;
952 
953  // Choose a sign-bit check for the compare (likely simpler for codegen).
954  // ABS: (X <s 0) ? -X : X
955  // NABS: (X <s 0) ? X : -X
956  Value *LHS, *RHS;
957  SelectPatternFlavor SPF = matchSelectPattern(&Sel, LHS, RHS).Flavor;
958  if (SPF != SelectPatternFlavor::SPF_ABS &&
960  return nullptr;
961 
962  Value *TVal = Sel.getTrueValue();
963  Value *FVal = Sel.getFalseValue();
964  assert(isKnownNegation(TVal, FVal) &&
965  "Unexpected result from matchSelectPattern");
966 
967  // The compare may use the negated abs()/nabs() operand, or it may use
968  // negation in non-canonical form such as: sub A, B.
969  bool CmpUsesNegatedOp = match(Cmp.getOperand(0), m_Neg(m_Specific(TVal))) ||
970  match(Cmp.getOperand(0), m_Neg(m_Specific(FVal)));
971 
972  bool CmpCanonicalized = !CmpUsesNegatedOp &&
973  match(Cmp.getOperand(1), m_ZeroInt()) &&
975  bool RHSCanonicalized = match(RHS, m_Neg(m_Specific(LHS)));
976 
977  // Is this already canonical?
978  if (CmpCanonicalized && RHSCanonicalized)
979  return nullptr;
980 
981  // If RHS is used by other instructions except compare and select, don't
982  // canonicalize it to not increase the instruction count.
983  if (!(RHS->hasOneUse() || (RHS->hasNUses(2) && CmpUsesNegatedOp)))
984  return nullptr;
985 
986  // Create the canonical compare: icmp slt LHS 0.
987  if (!CmpCanonicalized) {
990  if (CmpUsesNegatedOp)
991  Cmp.setOperand(0, LHS);
992  }
993 
994  // Create the canonical RHS: RHS = sub (0, LHS).
995  if (!RHSCanonicalized) {
996  assert(RHS->hasOneUse() && "RHS use number is not right");
997  RHS = Builder.CreateNeg(LHS);
998  if (TVal == LHS) {
999  Sel.setFalseValue(RHS);
1000  FVal = RHS;
1001  } else {
1002  Sel.setTrueValue(RHS);
1003  TVal = RHS;
1004  }
1005  }
1006 
1007  // If the select operands do not change, we're done.
1008  if (SPF == SelectPatternFlavor::SPF_NABS) {
1009  if (TVal == LHS)
1010  return &Sel;
1011  assert(FVal == LHS && "Unexpected results from matchSelectPattern");
1012  } else {
1013  if (FVal == LHS)
1014  return &Sel;
1015  assert(TVal == LHS && "Unexpected results from matchSelectPattern");
1016  }
1017 
1018  // We are swapping the select operands, so swap the metadata too.
1019  Sel.setTrueValue(FVal);
1020  Sel.setFalseValue(TVal);
1021  Sel.swapProfMetadata();
1022  return &Sel;
1023 }
1024 
1025 /// Visit a SelectInst that has an ICmpInst as its first operand.
1026 Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI,
1027  ICmpInst *ICI) {
1028  Value *TrueVal = SI.getTrueValue();
1029  Value *FalseVal = SI.getFalseValue();
1030 
1031  if (Instruction *NewSel = canonicalizeMinMaxWithConstant(SI, *ICI, Builder))
1032  return NewSel;
1033 
1034  if (Instruction *NewAbs = canonicalizeAbsNabs(SI, *ICI, Builder))
1035  return NewAbs;
1036 
1037  bool Changed = adjustMinMax(SI, *ICI);
1038 
1039  if (Value *V = foldSelectICmpAnd(SI, ICI, Builder))
1040  return replaceInstUsesWith(SI, V);
1041 
1042  // NOTE: if we wanted to, this is where to detect integer MIN/MAX
1043  ICmpInst::Predicate Pred = ICI->getPredicate();
1044  Value *CmpLHS = ICI->getOperand(0);
1045  Value *CmpRHS = ICI->getOperand(1);
1046  if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
1047  if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
1048  // Transform (X == C) ? X : Y -> (X == C) ? C : Y
1049  SI.setOperand(1, CmpRHS);
1050  Changed = true;
1051  } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
1052  // Transform (X != C) ? Y : X -> (X != C) ? Y : C
1053  SI.setOperand(2, CmpRHS);
1054  Changed = true;
1055  }
1056  }
1057 
1058  // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring
1059  // decomposeBitTestICmp() might help.
1060  {
1061  unsigned BitWidth =
1062  DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
1063  APInt MinSignedValue = APInt::getSignedMinValue(BitWidth);
1064  Value *X;
1065  const APInt *Y, *C;
1066  bool TrueWhenUnset;
1067  bool IsBitTest = false;
1068  if (ICmpInst::isEquality(Pred) &&
1069  match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) &&
1070  match(CmpRHS, m_Zero())) {
1071  IsBitTest = true;
1072  TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
1073  } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
1074  X = CmpLHS;
1075  Y = &MinSignedValue;
1076  IsBitTest = true;
1077  TrueWhenUnset = false;
1078  } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
1079  X = CmpLHS;
1080  Y = &MinSignedValue;
1081  IsBitTest = true;
1082  TrueWhenUnset = true;
1083  }
1084  if (IsBitTest) {
1085  Value *V = nullptr;
1086  // (X & Y) == 0 ? X : X ^ Y --> X & ~Y
1087  if (TrueWhenUnset && TrueVal == X &&
1088  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1089  V = Builder.CreateAnd(X, ~(*Y));
1090  // (X & Y) != 0 ? X ^ Y : X --> X & ~Y
1091  else if (!TrueWhenUnset && FalseVal == X &&
1092  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1093  V = Builder.CreateAnd(X, ~(*Y));
1094  // (X & Y) == 0 ? X ^ Y : X --> X | Y
1095  else if (TrueWhenUnset && FalseVal == X &&
1096  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1097  V = Builder.CreateOr(X, *Y);
1098  // (X & Y) != 0 ? X : X ^ Y --> X | Y
1099  else if (!TrueWhenUnset && TrueVal == X &&
1100  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1101  V = Builder.CreateOr(X, *Y);
1102 
1103  if (V)
1104  return replaceInstUsesWith(SI, V);
1105  }
1106  }
1107 
1108  if (Instruction *V =
1109  foldSelectICmpAndAnd(SI.getType(), ICI, TrueVal, FalseVal, Builder))
1110  return V;
1111 
1112  if (Value *V = foldSelectICmpAndOr(ICI, TrueVal, FalseVal, Builder))
1113  return replaceInstUsesWith(SI, V);
1114 
1115  if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
1116  return replaceInstUsesWith(SI, V);
1117 
1118  if (Value *V = canonicalizeSaturatedSubtract(ICI, TrueVal, FalseVal, Builder))
1119  return replaceInstUsesWith(SI, V);
1120 
1121  if (Value *V = canonicalizeSaturatedAdd(ICI, TrueVal, FalseVal, Builder))
1122  return replaceInstUsesWith(SI, V);
1123 
1124  return Changed ? &SI : nullptr;
1125 }
1126 
1127 /// SI is a select whose condition is a PHI node (but the two may be in
1128 /// different blocks). See if the true/false values (V) are live in all of the
1129 /// predecessor blocks of the PHI. For example, cases like this can't be mapped:
1130 ///
1131 /// X = phi [ C1, BB1], [C2, BB2]
1132 /// Y = add
1133 /// Z = select X, Y, 0
1134 ///
1135 /// because Y is not live in BB1/BB2.
1136 static bool canSelectOperandBeMappingIntoPredBlock(const Value *V,
1137  const SelectInst &SI) {
1138  // If the value is a non-instruction value like a constant or argument, it
1139  // can always be mapped.
1140  const Instruction *I = dyn_cast<Instruction>(V);
1141  if (!I) return true;
1142 
1143  // If V is a PHI node defined in the same block as the condition PHI, we can
1144  // map the arguments.
1145  const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
1146 
1147  if (const PHINode *VP = dyn_cast<PHINode>(I))
1148  if (VP->getParent() == CondPHI->getParent())
1149  return true;
1150 
1151  // Otherwise, if the PHI and select are defined in the same block and if V is
1152  // defined in a different block, then we can transform it.
1153  if (SI.getParent() == CondPHI->getParent() &&
1154  I->getParent() != CondPHI->getParent())
1155  return true;
1156 
1157  // Otherwise we have a 'hard' case and we can't tell without doing more
1158  // detailed dominator based analysis, punt.
1159  return false;
1160 }
1161 
1162 /// We have an SPF (e.g. a min or max) of an SPF of the form:
1163 /// SPF2(SPF1(A, B), C)
1164 Instruction *InstCombiner::foldSPFofSPF(Instruction *Inner,
1165  SelectPatternFlavor SPF1,
1166  Value *A, Value *B,
1167  Instruction &Outer,
1168  SelectPatternFlavor SPF2, Value *C) {
1169  if (Outer.getType() != Inner->getType())
1170  return nullptr;
1171 
1172  if (C == A || C == B) {
1173  // MAX(MAX(A, B), B) -> MAX(A, B)
1174  // MIN(MIN(a, b), a) -> MIN(a, b)
1175  // TODO: This could be done in instsimplify.
1176  if (SPF1 == SPF2 && SelectPatternResult::isMinOrMax(SPF1))
1177  return replaceInstUsesWith(Outer, Inner);
1178 
1179  // MAX(MIN(a, b), a) -> a
1180  // MIN(MAX(a, b), a) -> a
1181  // TODO: This could be done in instsimplify.
1182  if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
1183  (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
1184  (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
1185  (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
1186  return replaceInstUsesWith(Outer, C);
1187  }
1188 
1189  if (SPF1 == SPF2) {
1190  const APInt *CB, *CC;
1191  if (match(B, m_APInt(CB)) && match(C, m_APInt(CC))) {
1192  // MIN(MIN(A, 23), 97) -> MIN(A, 23)
1193  // MAX(MAX(A, 97), 23) -> MAX(A, 97)
1194  // TODO: This could be done in instsimplify.
1195  if ((SPF1 == SPF_UMIN && CB->ule(*CC)) ||
1196  (SPF1 == SPF_SMIN && CB->sle(*CC)) ||
1197  (SPF1 == SPF_UMAX && CB->uge(*CC)) ||
1198  (SPF1 == SPF_SMAX && CB->sge(*CC)))
1199  return replaceInstUsesWith(Outer, Inner);
1200 
1201  // MIN(MIN(A, 97), 23) -> MIN(A, 23)
1202  // MAX(MAX(A, 23), 97) -> MAX(A, 97)
1203  if ((SPF1 == SPF_UMIN && CB->ugt(*CC)) ||
1204  (SPF1 == SPF_SMIN && CB->sgt(*CC)) ||
1205  (SPF1 == SPF_UMAX && CB->ult(*CC)) ||
1206  (SPF1 == SPF_SMAX && CB->slt(*CC))) {
1207  Outer.replaceUsesOfWith(Inner, A);
1208  return &Outer;
1209  }
1210  }
1211  }
1212 
1213  // ABS(ABS(X)) -> ABS(X)
1214  // NABS(NABS(X)) -> NABS(X)
1215  // TODO: This could be done in instsimplify.
1216  if (SPF1 == SPF2 && (SPF1 == SPF_ABS || SPF1 == SPF_NABS)) {
1217  return replaceInstUsesWith(Outer, Inner);
1218  }
1219 
1220  // ABS(NABS(X)) -> ABS(X)
1221  // NABS(ABS(X)) -> NABS(X)
1222  if ((SPF1 == SPF_ABS && SPF2 == SPF_NABS) ||
1223  (SPF1 == SPF_NABS && SPF2 == SPF_ABS)) {
1224  SelectInst *SI = cast<SelectInst>(Inner);
1225  Value *NewSI =
1226  Builder.CreateSelect(SI->getCondition(), SI->getFalseValue(),
1227  SI->getTrueValue(), SI->getName(), SI);
1228  return replaceInstUsesWith(Outer, NewSI);
1229  }
1230 
1231  auto IsFreeOrProfitableToInvert =
1232  [&](Value *V, Value *&NotV, bool &ElidesXor) {
1233  if (match(V, m_Not(m_Value(NotV)))) {
1234  // If V has at most 2 uses then we can get rid of the xor operation
1235  // entirely.
1236  ElidesXor |= !V->hasNUsesOrMore(3);
1237  return true;
1238  }
1239 
1240  if (IsFreeToInvert(V, !V->hasNUsesOrMore(3))) {
1241  NotV = nullptr;
1242  return true;
1243  }
1244 
1245  return false;
1246  };
1247 
1248  Value *NotA, *NotB, *NotC;
1249  bool ElidesXor = false;
1250 
1251  // MIN(MIN(~A, ~B), ~C) == ~MAX(MAX(A, B), C)
1252  // MIN(MAX(~A, ~B), ~C) == ~MAX(MIN(A, B), C)
1253  // MAX(MIN(~A, ~B), ~C) == ~MIN(MAX(A, B), C)
1254  // MAX(MAX(~A, ~B), ~C) == ~MIN(MIN(A, B), C)
1255  //
1256  // This transform is performance neutral if we can elide at least one xor from
1257  // the set of three operands, since we'll be tacking on an xor at the very
1258  // end.
1259  if (SelectPatternResult::isMinOrMax(SPF1) &&
1261  IsFreeOrProfitableToInvert(A, NotA, ElidesXor) &&
1262  IsFreeOrProfitableToInvert(B, NotB, ElidesXor) &&
1263  IsFreeOrProfitableToInvert(C, NotC, ElidesXor) && ElidesXor) {
1264  if (!NotA)
1265  NotA = Builder.CreateNot(A);
1266  if (!NotB)
1267  NotB = Builder.CreateNot(B);
1268  if (!NotC)
1269  NotC = Builder.CreateNot(C);
1270 
1271  Value *NewInner = createMinMax(Builder, getInverseMinMaxFlavor(SPF1), NotA,
1272  NotB);
1273  Value *NewOuter = Builder.CreateNot(
1274  createMinMax(Builder, getInverseMinMaxFlavor(SPF2), NewInner, NotC));
1275  return replaceInstUsesWith(Outer, NewOuter);
1276  }
1277 
1278  return nullptr;
1279 }
1280 
1281 /// Turn select C, (X + Y), (X - Y) --> (X + (select C, Y, (-Y))).
1282 /// This is even legal for FP.
1283 static Instruction *foldAddSubSelect(SelectInst &SI,
1284  InstCombiner::BuilderTy &Builder) {
1285  Value *CondVal = SI.getCondition();
1286  Value *TrueVal = SI.getTrueValue();
1287  Value *FalseVal = SI.getFalseValue();
1288  auto *TI = dyn_cast<Instruction>(TrueVal);
1289  auto *FI = dyn_cast<Instruction>(FalseVal);
1290  if (!TI || !FI || !TI->hasOneUse() || !FI->hasOneUse())
1291  return nullptr;
1292 
1293  Instruction *AddOp = nullptr, *SubOp = nullptr;
1294  if ((TI->getOpcode() == Instruction::Sub &&
1295  FI->getOpcode() == Instruction::Add) ||
1296  (TI->getOpcode() == Instruction::FSub &&
1297  FI->getOpcode() == Instruction::FAdd)) {
1298  AddOp = FI;
1299  SubOp = TI;
1300  } else if ((FI->getOpcode() == Instruction::Sub &&
1301  TI->getOpcode() == Instruction::Add) ||
1302  (FI->getOpcode() == Instruction::FSub &&
1303  TI->getOpcode() == Instruction::FAdd)) {
1304  AddOp = TI;
1305  SubOp = FI;
1306  }
1307 
1308  if (AddOp) {
1309  Value *OtherAddOp = nullptr;
1310  if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
1311  OtherAddOp = AddOp->getOperand(1);
1312  } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
1313  OtherAddOp = AddOp->getOperand(0);
1314  }
1315 
1316  if (OtherAddOp) {
1317  // So at this point we know we have (Y -> OtherAddOp):
1318  // select C, (add X, Y), (sub X, Z)
1319  Value *NegVal; // Compute -Z
1320  if (SI.getType()->isFPOrFPVectorTy()) {
1321  NegVal = Builder.CreateFNeg(SubOp->getOperand(1));
1322  if (Instruction *NegInst = dyn_cast<Instruction>(NegVal)) {
1323  FastMathFlags Flags = AddOp->getFastMathFlags();
1324  Flags &= SubOp->getFastMathFlags();
1325  NegInst->setFastMathFlags(Flags);
1326  }
1327  } else {
1328  NegVal = Builder.CreateNeg(SubOp->getOperand(1));
1329  }
1330 
1331  Value *NewTrueOp = OtherAddOp;
1332  Value *NewFalseOp = NegVal;
1333  if (AddOp != TI)
1334  std::swap(NewTrueOp, NewFalseOp);
1335  Value *NewSel = Builder.CreateSelect(CondVal, NewTrueOp, NewFalseOp,
1336  SI.getName() + ".p", &SI);
1337 
1338  if (SI.getType()->isFPOrFPVectorTy()) {
1339  Instruction *RI =
1340  BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel);
1341 
1342  FastMathFlags Flags = AddOp->getFastMathFlags();
1343  Flags &= SubOp->getFastMathFlags();
1344  RI->setFastMathFlags(Flags);
1345  return RI;
1346  } else
1347  return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
1348  }
1349  }
1350  return nullptr;
1351 }
1352 
1353 Instruction *InstCombiner::foldSelectExtConst(SelectInst &Sel) {
1354  Constant *C;
1355  if (!match(Sel.getTrueValue(), m_Constant(C)) &&
1356  !match(Sel.getFalseValue(), m_Constant(C)))
1357  return nullptr;
1358 
1359  Instruction *ExtInst;
1360  if (!match(Sel.getTrueValue(), m_Instruction(ExtInst)) &&
1361  !match(Sel.getFalseValue(), m_Instruction(ExtInst)))
1362  return nullptr;
1363 
1364  auto ExtOpcode = ExtInst->getOpcode();
1365  if (ExtOpcode != Instruction::ZExt && ExtOpcode != Instruction::SExt)
1366  return nullptr;
1367 
1368  // If we are extending from a boolean type or if we can create a select that
1369  // has the same size operands as its condition, try to narrow the select.
1370  Value *X = ExtInst->getOperand(0);
1371  Type *SmallType = X->getType();
1372  Value *Cond = Sel.getCondition();
1373  auto *Cmp = dyn_cast<CmpInst>(Cond);
1374  if (!SmallType->isIntOrIntVectorTy(1) &&
1375  (!Cmp || Cmp->getOperand(0)->getType() != SmallType))
1376  return nullptr;
1377 
1378  // If the constant is the same after truncation to the smaller type and
1379  // extension to the original type, we can narrow the select.
1380  Type *SelType = Sel.getType();
1381  Constant *TruncC = ConstantExpr::getTrunc(C, SmallType);
1382  Constant *ExtC = ConstantExpr::getCast(ExtOpcode, TruncC, SelType);
1383  if (ExtC == C) {
1384  Value *TruncCVal = cast<Value>(TruncC);
1385  if (ExtInst == Sel.getFalseValue())
1386  std::swap(X, TruncCVal);
1387 
1388  // select Cond, (ext X), C --> ext(select Cond, X, C')
1389  // select Cond, C, (ext X) --> ext(select Cond, C', X)
1390  Value *NewSel = Builder.CreateSelect(Cond, X, TruncCVal, "narrow", &Sel);
1391  return CastInst::Create(Instruction::CastOps(ExtOpcode), NewSel, SelType);
1392  }
1393 
1394  // If one arm of the select is the extend of the condition, replace that arm
1395  // with the extension of the appropriate known bool value.
1396  if (Cond == X) {
1397  if (ExtInst == Sel.getTrueValue()) {
1398  // select X, (sext X), C --> select X, -1, C
1399  // select X, (zext X), C --> select X, 1, C
1400  Constant *One = ConstantInt::getTrue(SmallType);
1401  Constant *AllOnesOrOne = ConstantExpr::getCast(ExtOpcode, One, SelType);
1402  return SelectInst::Create(Cond, AllOnesOrOne, C, "", nullptr, &Sel);
1403  } else {
1404  // select X, C, (sext X) --> select X, C, 0
1405  // select X, C, (zext X) --> select X, C, 0
1406  Constant *Zero = ConstantInt::getNullValue(SelType);
1407  return SelectInst::Create(Cond, C, Zero, "", nullptr, &Sel);
1408  }
1409  }
1410 
1411  return nullptr;
1412 }
1413 
1414 /// Try to transform a vector select with a constant condition vector into a
1415 /// shuffle for easier combining with other shuffles and insert/extract.
1416 static Instruction *canonicalizeSelectToShuffle(SelectInst &SI) {
1417  Value *CondVal = SI.getCondition();
1418  Constant *CondC;
1419  if (!CondVal->getType()->isVectorTy() || !match(CondVal, m_Constant(CondC)))
1420  return nullptr;
1421 
1422  unsigned NumElts = CondVal->getType()->getVectorNumElements();
1424  Mask.reserve(NumElts);
1425  Type *Int32Ty = Type::getInt32Ty(CondVal->getContext());
1426  for (unsigned i = 0; i != NumElts; ++i) {
1427  Constant *Elt = CondC->getAggregateElement(i);
1428  if (!Elt)
1429  return nullptr;
1430 
1431  if (Elt->isOneValue()) {
1432  // If the select condition element is true, choose from the 1st vector.
1433  Mask.push_back(ConstantInt::get(Int32Ty, i));
1434  } else if (Elt->isNullValue()) {
1435  // If the select condition element is false, choose from the 2nd vector.
1436  Mask.push_back(ConstantInt::get(Int32Ty, i + NumElts));
1437  } else if (isa<UndefValue>(Elt)) {
1438  // Undef in a select condition (choose one of the operands) does not mean
1439  // the same thing as undef in a shuffle mask (any value is acceptable), so
1440  // give up.
1441  return nullptr;
1442  } else {
1443  // Bail out on a constant expression.
1444  return nullptr;
1445  }
1446  }
1447 
1448  return new ShuffleVectorInst(SI.getTrueValue(), SI.getFalseValue(),
1449  ConstantVector::get(Mask));
1450 }
1451 
1452 /// Reuse bitcasted operands between a compare and select:
1453 /// select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
1454 /// bitcast (select (cmp (bitcast C), (bitcast D)), (bitcast C), (bitcast D))
1455 static Instruction *foldSelectCmpBitcasts(SelectInst &Sel,
1456  InstCombiner::BuilderTy &Builder) {
1457  Value *Cond = Sel.getCondition();
1458  Value *TVal = Sel.getTrueValue();
1459  Value *FVal = Sel.getFalseValue();
1460 
1461  CmpInst::Predicate Pred;
1462  Value *A, *B;
1463  if (!match(Cond, m_Cmp(Pred, m_Value(A), m_Value(B))))
1464  return nullptr;
1465 
1466  // The select condition is a compare instruction. If the select's true/false
1467  // values are already the same as the compare operands, there's nothing to do.
1468  if (TVal == A || TVal == B || FVal == A || FVal == B)
1469  return nullptr;
1470 
1471  Value *C, *D;
1472  if (!match(A, m_BitCast(m_Value(C))) || !match(B, m_BitCast(m_Value(D))))
1473  return nullptr;
1474 
1475  // select (cmp (bitcast C), (bitcast D)), (bitcast TSrc), (bitcast FSrc)
1476  Value *TSrc, *FSrc;
1477  if (!match(TVal, m_BitCast(m_Value(TSrc))) ||
1478  !match(FVal, m_BitCast(m_Value(FSrc))))
1479  return nullptr;
1480 
1481  // If the select true/false values are *different bitcasts* of the same source
1482  // operands, make the select operands the same as the compare operands and
1483  // cast the result. This is the canonical select form for min/max.
1484  Value *NewSel;
1485  if (TSrc == C && FSrc == D) {
1486  // select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
1487  // bitcast (select (cmp A, B), A, B)
1488  NewSel = Builder.CreateSelect(Cond, A, B, "", &Sel);
1489  } else if (TSrc == D && FSrc == C) {
1490  // select (cmp (bitcast C), (bitcast D)), (bitcast' D), (bitcast' C) -->
1491  // bitcast (select (cmp A, B), B, A)
1492  NewSel = Builder.CreateSelect(Cond, B, A, "", &Sel);
1493  } else {
1494  return nullptr;
1495  }
1496  return CastInst::CreateBitOrPointerCast(NewSel, Sel.getType());
1497 }
1498 
1499 /// Try to eliminate select instructions that test the returned flag of cmpxchg
1500 /// instructions.
1501 ///
1502 /// If a select instruction tests the returned flag of a cmpxchg instruction and
1503 /// selects between the returned value of the cmpxchg instruction its compare
1504 /// operand, the result of the select will always be equal to its false value.
1505 /// For example:
1506 ///
1507 /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst
1508 /// %1 = extractvalue { i64, i1 } %0, 1
1509 /// %2 = extractvalue { i64, i1 } %0, 0
1510 /// %3 = select i1 %1, i64 %compare, i64 %2
1511 /// ret i64 %3
1512 ///
1513 /// The returned value of the cmpxchg instruction (%2) is the original value
1514 /// located at %ptr prior to any update. If the cmpxchg operation succeeds, %2
1515 /// must have been equal to %compare. Thus, the result of the select is always
1516 /// equal to %2, and the code can be simplified to:
1517 ///
1518 /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst
1519 /// %1 = extractvalue { i64, i1 } %0, 0
1520 /// ret i64 %1
1521 ///
1522 static Instruction *foldSelectCmpXchg(SelectInst &SI) {
1523  // A helper that determines if V is an extractvalue instruction whose
1524  // aggregate operand is a cmpxchg instruction and whose single index is equal
1525  // to I. If such conditions are true, the helper returns the cmpxchg
1526  // instruction; otherwise, a nullptr is returned.
1527  auto isExtractFromCmpXchg = [](Value *V, unsigned I) -> AtomicCmpXchgInst * {
1528  auto *Extract = dyn_cast<ExtractValueInst>(V);
1529  if (!Extract)
1530  return nullptr;
1531  if (Extract->getIndices()[0] != I)
1532  return nullptr;
1533  return dyn_cast<AtomicCmpXchgInst>(Extract->getAggregateOperand());
1534  };
1535 
1536  // If the select has a single user, and this user is a select instruction that
1537  // we can simplify, skip the cmpxchg simplification for now.
1538  if (SI.hasOneUse())
1539  if (auto *Select = dyn_cast<SelectInst>(SI.user_back()))
1540  if (Select->getCondition() == SI.getCondition())
1541  if (Select->getFalseValue() == SI.getTrueValue() ||
1542  Select->getTrueValue() == SI.getFalseValue())
1543  return nullptr;
1544 
1545  // Ensure the select condition is the returned flag of a cmpxchg instruction.
1546  auto *CmpXchg = isExtractFromCmpXchg(SI.getCondition(), 1);
1547  if (!CmpXchg)
1548  return nullptr;
1549 
1550  // Check the true value case: The true value of the select is the returned
1551  // value of the same cmpxchg used by the condition, and the false value is the
1552  // cmpxchg instruction's compare operand.
1553  if (auto *X = isExtractFromCmpXchg(SI.getTrueValue(), 0))
1554  if (X == CmpXchg && X->getCompareOperand() == SI.getFalseValue()) {
1555  SI.setTrueValue(SI.getFalseValue());
1556  return &SI;
1557  }
1558 
1559  // Check the false value case: The false value of the select is the returned
1560  // value of the same cmpxchg used by the condition, and the true value is the
1561  // cmpxchg instruction's compare operand.
1562  if (auto *X = isExtractFromCmpXchg(SI.getFalseValue(), 0))
1563  if (X == CmpXchg && X->getCompareOperand() == SI.getTrueValue()) {
1564  SI.setTrueValue(SI.getFalseValue());
1565  return &SI;
1566  }
1567 
1568  return nullptr;
1569 }
1570 
1571 static Instruction *moveAddAfterMinMax(SelectPatternFlavor SPF, Value *X,
1572  Value *Y,
1573  InstCombiner::BuilderTy &Builder) {
1574  assert(SelectPatternResult::isMinOrMax(SPF) && "Expected min/max pattern");
1575  bool IsUnsigned = SPF == SelectPatternFlavor::SPF_UMIN ||
1577  // TODO: If InstSimplify could fold all cases where C2 <= C1, we could change
1578  // the constant value check to an assert.
1579  Value *A;
1580  const APInt *C1, *C2;
1581  if (IsUnsigned && match(X, m_NUWAdd(m_Value(A), m_APInt(C1))) &&
1582  match(Y, m_APInt(C2)) && C2->uge(*C1) && X->hasNUses(2)) {
1583  // umin (add nuw A, C1), C2 --> add nuw (umin A, C2 - C1), C1
1584  // umax (add nuw A, C1), C2 --> add nuw (umax A, C2 - C1), C1
1585  Value *NewMinMax = createMinMax(Builder, SPF, A,
1586  ConstantInt::get(X->getType(), *C2 - *C1));
1588  ConstantInt::get(X->getType(), *C1));
1589  }
1590 
1591  if (!IsUnsigned && match(X, m_NSWAdd(m_Value(A), m_APInt(C1))) &&
1592  match(Y, m_APInt(C2)) && X->hasNUses(2)) {
1593  bool Overflow;
1594  APInt Diff = C2->ssub_ov(*C1, Overflow);
1595  if (!Overflow) {
1596  // smin (add nsw A, C1), C2 --> add nsw (smin A, C2 - C1), C1
1597  // smax (add nsw A, C1), C2 --> add nsw (smax A, C2 - C1), C1
1598  Value *NewMinMax = createMinMax(Builder, SPF, A,
1599  ConstantInt::get(X->getType(), Diff));
1601  ConstantInt::get(X->getType(), *C1));
1602  }
1603  }
1604 
1605  return nullptr;
1606 }
1607 
1608 /// Reduce a sequence of min/max with a common operand.
1609 static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS,
1610  Value *RHS,
1611  InstCombiner::BuilderTy &Builder) {
1612  assert(SelectPatternResult::isMinOrMax(SPF) && "Expected a min/max");
1613  // TODO: Allow FP min/max with nnan/nsz.
1614  if (!LHS->getType()->isIntOrIntVectorTy())
1615  return nullptr;
1616 
1617  // Match 3 of the same min/max ops. Example: umin(umin(), umin()).
1618  Value *A, *B, *C, *D;
1619  SelectPatternResult L = matchSelectPattern(LHS, A, B);
1620  SelectPatternResult R = matchSelectPattern(RHS, C, D);
1621  if (SPF != L.Flavor || L.Flavor != R.Flavor)
1622  return nullptr;
1623 
1624  // Look for a common operand. The use checks are different than usual because
1625  // a min/max pattern typically has 2 uses of each op: 1 by the cmp and 1 by
1626  // the select.
1627  Value *MinMaxOp = nullptr;
1628  Value *ThirdOp = nullptr;
1629  if (!LHS->hasNUsesOrMore(3) && RHS->hasNUsesOrMore(3)) {
1630  // If the LHS is only used in this chain and the RHS is used outside of it,
1631  // reuse the RHS min/max because that will eliminate the LHS.
1632  if (D == A || C == A) {
1633  // min(min(a, b), min(c, a)) --> min(min(c, a), b)
1634  // min(min(a, b), min(a, d)) --> min(min(a, d), b)
1635  MinMaxOp = RHS;
1636  ThirdOp = B;
1637  } else if (D == B || C == B) {
1638  // min(min(a, b), min(c, b)) --> min(min(c, b), a)
1639  // min(min(a, b), min(b, d)) --> min(min(b, d), a)
1640  MinMaxOp = RHS;
1641  ThirdOp = A;
1642  }
1643  } else if (!RHS->hasNUsesOrMore(3)) {
1644  // Reuse the LHS. This will eliminate the RHS.
1645  if (D == A || D == B) {
1646  // min(min(a, b), min(c, a)) --> min(min(a, b), c)
1647  // min(min(a, b), min(c, b)) --> min(min(a, b), c)
1648  MinMaxOp = LHS;
1649  ThirdOp = C;
1650  } else if (C == A || C == B) {
1651  // min(min(a, b), min(b, d)) --> min(min(a, b), d)
1652  // min(min(a, b), min(c, b)) --> min(min(a, b), d)
1653  MinMaxOp = LHS;
1654  ThirdOp = D;
1655  }
1656  }
1657  if (!MinMaxOp || !ThirdOp)
1658  return nullptr;
1659 
1661  Value *CmpABC = Builder.CreateICmp(P, MinMaxOp, ThirdOp);
1662  return SelectInst::Create(CmpABC, MinMaxOp, ThirdOp);
1663 }
1664 
1665 /// Try to reduce a rotate pattern that includes a compare and select into a
1666 /// funnel shift intrinsic. Example:
1667 /// rotl32(a, b) --> (b == 0 ? a : ((a >> (32 - b)) | (a << b)))
1668 /// --> call llvm.fshl.i32(a, a, b)
1669 static Instruction *foldSelectRotate(SelectInst &Sel) {
1670  // The false value of the select must be a rotate of the true value.
1671  Value *Or0, *Or1;
1672  if (!match(Sel.getFalseValue(), m_OneUse(m_Or(m_Value(Or0), m_Value(Or1)))))
1673  return nullptr;
1674 
1675  Value *TVal = Sel.getTrueValue();
1676  Value *SA0, *SA1;
1677  if (!match(Or0, m_OneUse(m_LogicalShift(m_Specific(TVal), m_Value(SA0)))) ||
1678  !match(Or1, m_OneUse(m_LogicalShift(m_Specific(TVal), m_Value(SA1)))))
1679  return nullptr;
1680 
1681  auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode();
1682  auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode();
1683  if (ShiftOpcode0 == ShiftOpcode1)
1684  return nullptr;
1685 
1686  // We have one of these patterns so far:
1687  // select ?, TVal, (or (lshr TVal, SA0), (shl TVal, SA1))
1688  // select ?, TVal, (or (shl TVal, SA0), (lshr TVal, SA1))
1689  // This must be a power-of-2 rotate for a bitmasking transform to be valid.
1690  unsigned Width = Sel.getType()->getScalarSizeInBits();
1691  if (!isPowerOf2_32(Width))
1692  return nullptr;
1693 
1694  // Check the shift amounts to see if they are an opposite pair.
1695  Value *ShAmt;
1696  if (match(SA1, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(SA0)))))
1697  ShAmt = SA0;
1698  else if (match(SA0, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(SA1)))))
1699  ShAmt = SA1;
1700  else
1701  return nullptr;
1702 
1703  // Finally, see if the select is filtering out a shift-by-zero.
1704  Value *Cond = Sel.getCondition();
1705  ICmpInst::Predicate Pred;
1706  if (!match(Cond, m_OneUse(m_ICmp(Pred, m_Specific(ShAmt), m_ZeroInt()))) ||
1707  Pred != ICmpInst::ICMP_EQ)
1708  return nullptr;
1709 
1710  // This is a rotate that avoids shift-by-bitwidth UB in a suboptimal way.
1711  // Convert to funnel shift intrinsic.
1712  bool IsFshl = (ShAmt == SA0 && ShiftOpcode0 == BinaryOperator::Shl) ||
1713  (ShAmt == SA1 && ShiftOpcode1 == BinaryOperator::Shl);
1714  Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
1715  Function *F = Intrinsic::getDeclaration(Sel.getModule(), IID, Sel.getType());
1716  return IntrinsicInst::Create(F, { TVal, TVal, ShAmt });
1717 }
1718 
1720  Value *CondVal = SI.getCondition();
1721  Value *TrueVal = SI.getTrueValue();
1722  Value *FalseVal = SI.getFalseValue();
1723  Type *SelType = SI.getType();
1724 
1725  // FIXME: Remove this workaround when freeze related patches are done.
1726  // For select with undef operand which feeds into an equality comparison,
1727  // don't simplify it so loop unswitch can know the equality comparison
1728  // may have an undef operand. This is a workaround for PR31652 caused by
1729  // descrepancy about branch on undef between LoopUnswitch and GVN.
1730  if (isa<UndefValue>(TrueVal) || isa<UndefValue>(FalseVal)) {
1731  if (llvm::any_of(SI.users(), [&](User *U) {
1732  ICmpInst *CI = dyn_cast<ICmpInst>(U);
1733  if (CI && CI->isEquality())
1734  return true;
1735  return false;
1736  })) {
1737  return nullptr;
1738  }
1739  }
1740 
1741  if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal,
1742  SQ.getWithInstruction(&SI)))
1743  return replaceInstUsesWith(SI, V);
1744 
1745  if (Instruction *I = canonicalizeSelectToShuffle(SI))
1746  return I;
1747 
1748  // Canonicalize a one-use integer compare with a non-canonical predicate by
1749  // inverting the predicate and swapping the select operands. This matches a
1750  // compare canonicalization for conditional branches.
1751  // TODO: Should we do the same for FP compares?
1752  CmpInst::Predicate Pred;
1753  if (match(CondVal, m_OneUse(m_ICmp(Pred, m_Value(), m_Value()))) &&
1754  !isCanonicalPredicate(Pred)) {
1755  // Swap true/false values and condition.
1756  CmpInst *Cond = cast<CmpInst>(CondVal);
1758  SI.setOperand(1, FalseVal);
1759  SI.setOperand(2, TrueVal);
1760  SI.swapProfMetadata();
1761  Worklist.Add(Cond);
1762  return &SI;
1763  }
1764 
1765  if (SelType->isIntOrIntVectorTy(1) &&
1766  TrueVal->getType() == CondVal->getType()) {
1767  if (match(TrueVal, m_One())) {
1768  // Change: A = select B, true, C --> A = or B, C
1769  return BinaryOperator::CreateOr(CondVal, FalseVal);
1770  }
1771  if (match(TrueVal, m_Zero())) {
1772  // Change: A = select B, false, C --> A = and !B, C
1773  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1774  return BinaryOperator::CreateAnd(NotCond, FalseVal);
1775  }
1776  if (match(FalseVal, m_Zero())) {
1777  // Change: A = select B, C, false --> A = and B, C
1778  return BinaryOperator::CreateAnd(CondVal, TrueVal);
1779  }
1780  if (match(FalseVal, m_One())) {
1781  // Change: A = select B, C, true --> A = or !B, C
1782  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1783  return BinaryOperator::CreateOr(NotCond, TrueVal);
1784  }
1785 
1786  // select a, a, b -> a | b
1787  // select a, b, a -> a & b
1788  if (CondVal == TrueVal)
1789  return BinaryOperator::CreateOr(CondVal, FalseVal);
1790  if (CondVal == FalseVal)
1791  return BinaryOperator::CreateAnd(CondVal, TrueVal);
1792 
1793  // select a, ~a, b -> (~a) & b
1794  // select a, b, ~a -> (~a) | b
1795  if (match(TrueVal, m_Not(m_Specific(CondVal))))
1796  return BinaryOperator::CreateAnd(TrueVal, FalseVal);
1797  if (match(FalseVal, m_Not(m_Specific(CondVal))))
1798  return BinaryOperator::CreateOr(TrueVal, FalseVal);
1799  }
1800 
1801  // Selecting between two integer or vector splat integer constants?
1802  //
1803  // Note that we don't handle a scalar select of vectors:
1804  // select i1 %c, <2 x i8> <1, 1>, <2 x i8> <0, 0>
1805  // because that may need 3 instructions to splat the condition value:
1806  // extend, insertelement, shufflevector.
1807  if (SelType->isIntOrIntVectorTy() &&
1808  CondVal->getType()->isVectorTy() == SelType->isVectorTy()) {
1809  // select C, 1, 0 -> zext C to int
1810  if (match(TrueVal, m_One()) && match(FalseVal, m_Zero()))
1811  return new ZExtInst(CondVal, SelType);
1812 
1813  // select C, -1, 0 -> sext C to int
1814  if (match(TrueVal, m_AllOnes()) && match(FalseVal, m_Zero()))
1815  return new SExtInst(CondVal, SelType);
1816 
1817  // select C, 0, 1 -> zext !C to int
1818  if (match(TrueVal, m_Zero()) && match(FalseVal, m_One())) {
1819  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1820  return new ZExtInst(NotCond, SelType);
1821  }
1822 
1823  // select C, 0, -1 -> sext !C to int
1824  if (match(TrueVal, m_Zero()) && match(FalseVal, m_AllOnes())) {
1825  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1826  return new SExtInst(NotCond, SelType);
1827  }
1828  }
1829 
1830  // See if we are selecting two values based on a comparison of the two values.
1831  if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
1832  if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
1833  // Canonicalize to use ordered comparisons by swapping the select
1834  // operands.
1835  //
1836  // e.g.
1837  // (X ugt Y) ? X : Y -> (X ole Y) ? Y : X
1838  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
1839  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
1840  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1841  Builder.setFastMathFlags(FCI->getFastMathFlags());
1842  Value *NewCond = Builder.CreateFCmp(InvPred, TrueVal, FalseVal,
1843  FCI->getName() + ".inv");
1844 
1845  return SelectInst::Create(NewCond, FalseVal, TrueVal,
1846  SI.getName() + ".p");
1847  }
1848 
1849  // NOTE: if we wanted to, this is where to detect MIN/MAX
1850  } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
1851  // Canonicalize to use ordered comparisons by swapping the select
1852  // operands.
1853  //
1854  // e.g.
1855  // (X ugt Y) ? X : Y -> (X ole Y) ? X : Y
1856  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
1857  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
1858  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1859  Builder.setFastMathFlags(FCI->getFastMathFlags());
1860  Value *NewCond = Builder.CreateFCmp(InvPred, FalseVal, TrueVal,
1861  FCI->getName() + ".inv");
1862 
1863  return SelectInst::Create(NewCond, FalseVal, TrueVal,
1864  SI.getName() + ".p");
1865  }
1866 
1867  // NOTE: if we wanted to, this is where to detect MIN/MAX
1868  }
1869 
1870  // Canonicalize select with fcmp to fabs(). -0.0 makes this tricky. We need
1871  // fast-math-flags (nsz) or fsub with +0.0 (not fneg) for this to work. We
1872  // also require nnan because we do not want to unintentionally change the
1873  // sign of a NaN value.
1874  Value *X = FCI->getOperand(0);
1875  FCmpInst::Predicate Pred = FCI->getPredicate();
1876  if (match(FCI->getOperand(1), m_AnyZeroFP()) && FCI->hasNoNaNs()) {
1877  // (X <= +/-0.0) ? (0.0 - X) : X --> fabs(X)
1878  // (X > +/-0.0) ? X : (0.0 - X) --> fabs(X)
1879  if ((X == FalseVal && Pred == FCmpInst::FCMP_OLE &&
1880  match(TrueVal, m_FSub(m_PosZeroFP(), m_Specific(X)))) ||
1881  (X == TrueVal && Pred == FCmpInst::FCMP_OGT &&
1882  match(FalseVal, m_FSub(m_PosZeroFP(), m_Specific(X))))) {
1883  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, X, FCI);
1884  return replaceInstUsesWith(SI, Fabs);
1885  }
1886  // With nsz:
1887  // (X < +/-0.0) ? -X : X --> fabs(X)
1888  // (X <= +/-0.0) ? -X : X --> fabs(X)
1889  // (X > +/-0.0) ? X : -X --> fabs(X)
1890  // (X >= +/-0.0) ? X : -X --> fabs(X)
1891  if (FCI->hasNoSignedZeros() &&
1892  ((X == FalseVal && match(TrueVal, m_FNeg(m_Specific(X))) &&
1893  (Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_OLE)) ||
1894  (X == TrueVal && match(FalseVal, m_FNeg(m_Specific(X))) &&
1895  (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_OGE)))) {
1896  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, X, FCI);
1897  return replaceInstUsesWith(SI, Fabs);
1898  }
1899  }
1900  }
1901 
1902  // See if we are selecting two values based on a comparison of the two values.
1903  if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
1904  if (Instruction *Result = foldSelectInstWithICmp(SI, ICI))
1905  return Result;
1906 
1907  if (Instruction *Add = foldAddSubSelect(SI, Builder))
1908  return Add;
1909 
1910  // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
1911  auto *TI = dyn_cast<Instruction>(TrueVal);
1912  auto *FI = dyn_cast<Instruction>(FalseVal);
1913  if (TI && FI && TI->getOpcode() == FI->getOpcode())
1914  if (Instruction *IV = foldSelectOpOp(SI, TI, FI))
1915  return IV;
1916 
1917  if (Instruction *I = foldSelectExtConst(SI))
1918  return I;
1919 
1920  // See if we can fold the select into one of our operands.
1921  if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) {
1922  if (Instruction *FoldI = foldSelectIntoOp(SI, TrueVal, FalseVal))
1923  return FoldI;
1924 
1925  Value *LHS, *RHS;
1926  Instruction::CastOps CastOp;
1927  SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp);
1928  auto SPF = SPR.Flavor;
1929  if (SPF) {
1930  Value *LHS2, *RHS2;
1931  if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor)
1932  if (Instruction *R = foldSPFofSPF(cast<Instruction>(LHS), SPF2, LHS2,
1933  RHS2, SI, SPF, RHS))
1934  return R;
1935  if (SelectPatternFlavor SPF2 = matchSelectPattern(RHS, LHS2, RHS2).Flavor)
1936  if (Instruction *R = foldSPFofSPF(cast<Instruction>(RHS), SPF2, LHS2,
1937  RHS2, SI, SPF, LHS))
1938  return R;
1939  // TODO.
1940  // ABS(-X) -> ABS(X)
1941  }
1942 
1944  // Canonicalize so that
1945  // - type casts are outside select patterns.
1946  // - float clamp is transformed to min/max pattern
1947 
1948  bool IsCastNeeded = LHS->getType() != SelType;
1949  Value *CmpLHS = cast<CmpInst>(CondVal)->getOperand(0);
1950  Value *CmpRHS = cast<CmpInst>(CondVal)->getOperand(1);
1951  if (IsCastNeeded ||
1952  (LHS->getType()->isFPOrFPVectorTy() &&
1953  ((CmpLHS != LHS && CmpLHS != RHS) ||
1954  (CmpRHS != LHS && CmpRHS != RHS)))) {
1955  CmpInst::Predicate Pred = getMinMaxPred(SPF, SPR.Ordered);
1956 
1957  Value *Cmp;
1958  if (CmpInst::isIntPredicate(Pred)) {
1959  Cmp = Builder.CreateICmp(Pred, LHS, RHS);
1960  } else {
1961  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1962  auto FMF = cast<FPMathOperator>(SI.getCondition())->getFastMathFlags();
1963  Builder.setFastMathFlags(FMF);
1964  Cmp = Builder.CreateFCmp(Pred, LHS, RHS);
1965  }
1966 
1967  Value *NewSI = Builder.CreateSelect(Cmp, LHS, RHS, SI.getName(), &SI);
1968  if (!IsCastNeeded)
1969  return replaceInstUsesWith(SI, NewSI);
1970 
1971  Value *NewCast = Builder.CreateCast(CastOp, NewSI, SelType);
1972  return replaceInstUsesWith(SI, NewCast);
1973  }
1974 
1975  // MAX(~a, ~b) -> ~MIN(a, b)
1976  // MAX(~a, C) -> ~MIN(a, ~C)
1977  // MIN(~a, ~b) -> ~MAX(a, b)
1978  // MIN(~a, C) -> ~MAX(a, ~C)
1979  auto moveNotAfterMinMax = [&](Value *X, Value *Y) -> Instruction * {
1980  Value *A;
1981  if (match(X, m_Not(m_Value(A))) && !X->hasNUsesOrMore(3) &&
1982  !IsFreeToInvert(A, A->hasOneUse()) &&
1983  // Passing false to only consider m_Not and constants.
1984  IsFreeToInvert(Y, false)) {
1985  Value *B = Builder.CreateNot(Y);
1986  Value *NewMinMax = createMinMax(Builder, getInverseMinMaxFlavor(SPF),
1987  A, B);
1988  // Copy the profile metadata.
1989  if (MDNode *MD = SI.getMetadata(LLVMContext::MD_prof)) {
1990  cast<SelectInst>(NewMinMax)->setMetadata(LLVMContext::MD_prof, MD);
1991  // Swap the metadata if the operands are swapped.
1992  if (X == SI.getFalseValue() && Y == SI.getTrueValue())
1993  cast<SelectInst>(NewMinMax)->swapProfMetadata();
1994  }
1995 
1996  return BinaryOperator::CreateNot(NewMinMax);
1997  }
1998 
1999  return nullptr;
2000  };
2001 
2002  if (Instruction *I = moveNotAfterMinMax(LHS, RHS))
2003  return I;
2004  if (Instruction *I = moveNotAfterMinMax(RHS, LHS))
2005  return I;
2006 
2007  if (Instruction *I = moveAddAfterMinMax(SPF, LHS, RHS, Builder))
2008  return I;
2009 
2010  if (Instruction *I = factorizeMinMaxTree(SPF, LHS, RHS, Builder))
2011  return I;
2012  }
2013  }
2014 
2015  // See if we can fold the select into a phi node if the condition is a select.
2016  if (auto *PN = dyn_cast<PHINode>(SI.getCondition()))
2017  // The true/false values have to be live in the PHI predecessor's blocks.
2018  if (canSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
2019  canSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
2020  if (Instruction *NV = foldOpIntoPhi(SI, PN))
2021  return NV;
2022 
2023  if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
2024  if (TrueSI->getCondition()->getType() == CondVal->getType()) {
2025  // select(C, select(C, a, b), c) -> select(C, a, c)
2026  if (TrueSI->getCondition() == CondVal) {
2027  if (SI.getTrueValue() == TrueSI->getTrueValue())
2028  return nullptr;
2029  SI.setOperand(1, TrueSI->getTrueValue());
2030  return &SI;
2031  }
2032  // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
2033  // We choose this as normal form to enable folding on the And and shortening
2034  // paths for the values (this helps GetUnderlyingObjects() for example).
2035  if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
2036  Value *And = Builder.CreateAnd(CondVal, TrueSI->getCondition());
2037  SI.setOperand(0, And);
2038  SI.setOperand(1, TrueSI->getTrueValue());
2039  return &SI;
2040  }
2041  }
2042  }
2043  if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
2044  if (FalseSI->getCondition()->getType() == CondVal->getType()) {
2045  // select(C, a, select(C, b, c)) -> select(C, a, c)
2046  if (FalseSI->getCondition() == CondVal) {
2047  if (SI.getFalseValue() == FalseSI->getFalseValue())
2048  return nullptr;
2049  SI.setOperand(2, FalseSI->getFalseValue());
2050  return &SI;
2051  }
2052  // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
2053  if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
2054  Value *Or = Builder.CreateOr(CondVal, FalseSI->getCondition());
2055  SI.setOperand(0, Or);
2056  SI.setOperand(2, FalseSI->getFalseValue());
2057  return &SI;
2058  }
2059  }
2060  }
2061 
2062  auto canMergeSelectThroughBinop = [](BinaryOperator *BO) {
2063  // The select might be preventing a division by 0.
2064  switch (BO->getOpcode()) {
2065  default:
2066  return true;
2067  case Instruction::SRem:
2068  case Instruction::URem:
2069  case Instruction::SDiv:
2070  case Instruction::UDiv:
2071  return false;
2072  }
2073  };
2074 
2075  // Try to simplify a binop sandwiched between 2 selects with the same
2076  // condition.
2077  // select(C, binop(select(C, X, Y), W), Z) -> select(C, binop(X, W), Z)
2078  BinaryOperator *TrueBO;
2079  if (match(TrueVal, m_OneUse(m_BinOp(TrueBO))) &&
2080  canMergeSelectThroughBinop(TrueBO)) {
2081  if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(0))) {
2082  if (TrueBOSI->getCondition() == CondVal) {
2083  TrueBO->setOperand(0, TrueBOSI->getTrueValue());
2084  Worklist.Add(TrueBO);
2085  return &SI;
2086  }
2087  }
2088  if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(1))) {
2089  if (TrueBOSI->getCondition() == CondVal) {
2090  TrueBO->setOperand(1, TrueBOSI->getTrueValue());
2091  Worklist.Add(TrueBO);
2092  return &SI;
2093  }
2094  }
2095  }
2096 
2097  // select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W))
2098  BinaryOperator *FalseBO;
2099  if (match(FalseVal, m_OneUse(m_BinOp(FalseBO))) &&
2100  canMergeSelectThroughBinop(FalseBO)) {
2101  if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(0))) {
2102  if (FalseBOSI->getCondition() == CondVal) {
2103  FalseBO->setOperand(0, FalseBOSI->getFalseValue());
2104  Worklist.Add(FalseBO);
2105  return &SI;
2106  }
2107  }
2108  if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(1))) {
2109  if (FalseBOSI->getCondition() == CondVal) {
2110  FalseBO->setOperand(1, FalseBOSI->getFalseValue());
2111  Worklist.Add(FalseBO);
2112  return &SI;
2113  }
2114  }
2115  }
2116 
2117  Value *NotCond;
2118  if (match(CondVal, m_Not(m_Value(NotCond)))) {
2119  SI.setOperand(0, NotCond);
2120  SI.setOperand(1, FalseVal);
2121  SI.setOperand(2, TrueVal);
2122  SI.swapProfMetadata();
2123  return &SI;
2124  }
2125 
2126  if (VectorType *VecTy = dyn_cast<VectorType>(SelType)) {
2127  unsigned VWidth = VecTy->getNumElements();
2128  APInt UndefElts(VWidth, 0);
2129  APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
2130  if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) {
2131  if (V != &SI)
2132  return replaceInstUsesWith(SI, V);
2133  return &SI;
2134  }
2135  }
2136 
2137  // If we can compute the condition, there's no need for a select.
2138  // Like the above fold, we are attempting to reduce compile-time cost by
2139  // putting this fold here with limitations rather than in InstSimplify.
2140  // The motivation for this call into value tracking is to take advantage of
2141  // the assumption cache, so make sure that is populated.
2142  if (!CondVal->getType()->isVectorTy() && !AC.assumptions().empty()) {
2143  KnownBits Known(1);
2144  computeKnownBits(CondVal, Known, 0, &SI);
2145  if (Known.One.isOneValue())
2146  return replaceInstUsesWith(SI, TrueVal);
2147  if (Known.Zero.isOneValue())
2148  return replaceInstUsesWith(SI, FalseVal);
2149  }
2150 
2151  if (Instruction *BitCastSel = foldSelectCmpBitcasts(SI, Builder))
2152  return BitCastSel;
2153 
2154  // Simplify selects that test the returned flag of cmpxchg instructions.
2155  if (Instruction *Select = foldSelectCmpXchg(SI))
2156  return Select;
2157 
2158  if (Instruction *Select = foldSelectBinOpIdentity(SI, TLI))
2159  return Select;
2160 
2161  if (Instruction *Rot = foldSelectRotate(SI))
2162  return Rot;
2163 
2164  return nullptr;
2165 }
MaxMin_match< ICmpInst, LHS, RHS, umin_pred_ty > m_UMin(const LHS &L, const RHS &R)
bool isFPPredicate() const
Definition: InstrTypes.h:801
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:756
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:594
static Instruction * foldSelectBinOpIdentity(SelectInst &Sel, const TargetLibraryInfo &TLI)
Replace a select operand based on an equality comparison with the identity constant of a binop...
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:70
Value * CreateICmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1984
This class is the base class for the comparison instructions.
Definition: InstrTypes.h:699
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...
static bool IsFreeToInvert(Value *V, bool WillInvertAllUses)
Return true if the specified value is free to invert (apply ~ to).
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:78
This instruction extracts a struct member or array element value from an aggregate value...
static APInt getAllOnesValue(unsigned numBits)
Get the all-ones value.
Definition: APInt.h:561
BinaryOp_match< LHS, RHS, Instruction::Sub > m_Sub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:653
is_zero m_Zero()
Match any null constant or a vector with all elements equal to 0.
Definition: PatternMatch.h:375
DiagnosticInfoOptimizationBase::Argument NV
static BinaryOperator * CreateNot(Value *Op, const Twine &Name="", Instruction *InsertBefore=nullptr)
Value * CreateIsNotNull(Value *Arg, const Twine &Name="")
Return an i1 value testing if Arg is not null.
Definition: IRBuilder.h:2152
Unsigned minimum.
Value * CreateZExtOrTrunc(Value *V, Type *DestTy, const Twine &Name="")
Create a ZExt or Trunc from the integer value V to DestTy.
Definition: IRBuilder.h:1704
This class represents lattice values for constants.
Definition: AllocatorList.h:23
BinaryOps getOpcode() const
Definition: InstrTypes.h:379
Value * CreateXor(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1235
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:528
static CallInst * Create(FunctionType *Ty, Value *F, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
This class represents zero extension of integer types.
static GetElementPtrInst * Create(Type *PointeeType, Value *Ptr, ArrayRef< Value *> IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Definition: Instructions.h:899
bool slt(const APInt &RHS) const
Signed less than comparison.
Definition: APInt.h:1203
class_match< Constant > m_Constant()
Match an arbitrary Constant and ignore it.
Definition: PatternMatch.h:89
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
unsigned less or equal
Definition: InstrTypes.h:735
unsigned less than
Definition: InstrTypes.h:734
0 1 0 0 True if ordered and less than
Definition: InstrTypes.h:715
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:709
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...
1 1 1 0 True if unordered or not equal
Definition: InstrTypes.h:725
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 greather than comparison.
Definition: APInt.h:1273
static bool isEquality(Predicate P)
Return true if this predicate is either EQ or NE.
void setArgOperand(unsigned i, Value *v)
Definition: InstrTypes.h:1223
Metadata node.
Definition: Metadata.h:863
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:659
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:229
void reserve(size_type N)
Definition: SmallVector.h:369
bool sle(const APInt &RHS) const
Signed less or equal comparison.
Definition: APInt.h:1238
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.
cst_pred_ty< is_zero_int > m_ZeroInt()
Match an integer 0 or a vector with all elements equal to 0.
Definition: PatternMatch.h:363
bool Ordered
Only applicable if Flavor is SPF_FMINNUM or SPF_FMAXNUM.
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1508
Signed maximum.
BinOpPred_match< LHS, RHS, is_logical_shift_op > m_LogicalShift(const LHS &L, const RHS &R)
Matches logical shift operations.
Definition: PatternMatch.h:948
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:274
Value * CreateNot(Value *V, const Twine &Name="")
Definition: IRBuilder.h:1369
Value * getArgOperand(unsigned i) const
Definition: InstrTypes.h:1218
static BinaryOperator * CreateNSW(BinaryOps Opc, Value *V1, Value *V2, const Twine &Name="")
Definition: InstrTypes.h:266
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:47
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:768
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:808
Absolute value.
static Optional< unsigned > getOpcode(ArrayRef< VPValue *> Values)
Returns the opcode of Values or ~0 if they do not all agree.
Definition: VPlanSLP.cpp:196
bool isUnsigned() const
Definition: InstrTypes.h:885
CastClass_match< OpTy, Instruction::Trunc > m_Trunc(const OpTy &Op)
Matches Trunc.
0 1 0 1 True if ordered and less than or equal
Definition: InstrTypes.h:716
static Constant * getSExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1660
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:641
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1674
Instruction * clone() const
Create a copy of &#39;this&#39; instruction that is identical in all ways except the following: ...
OverflowingBinaryOp_match< LHS, RHS, Instruction::Add, OverflowingBinaryOperator::NoUnsignedWrap > m_NUWAdd(const LHS &L, const RHS &R)
Definition: PatternMatch.h:852
bool isNullValue() const
Return true if this is the value that would be returned by getNullValue.
Definition: Constants.cpp:84
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
CastClass_match< OpTy, Instruction::ZExt > m_ZExt(const OpTy &Op)
Matches ZExt.
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< 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:234
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:125
cstfp_pred_ty< is_pos_zero_fp > m_PosZeroFP()
Match a floating-point positive zero.
Definition: PatternMatch.h:444
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:202
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:733
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:384
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:291
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:1022
static BinaryOperator * CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
Value * getOperand(unsigned i) const
Definition: User.h:169
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:20
Value * CreateOr(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1217
Constant * getAggregateElement(unsigned Elt) const
For aggregates (struct/array/vector) return the constant that corresponds to the specified element if...
Definition: Constants.cpp:344
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:303
Value * CreateFCmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1992
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:61
#define P(N)
BinaryOp_match< LHS, RHS, Instruction::LShr > m_LShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:780
bool hasNUsesOrMore(unsigned N) const
Return true if this value has N users or more.
Definition: Value.cpp:135
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:395
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:131
apint_match m_APInt(const APInt *&Res)
Match a ConstantInt or splatted ConstantVector, binding the specified pointer to the contained APInt...
Definition: PatternMatch.h:175
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:428
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
BinaryOp_match< LHS, RHS, Instruction::Or > m_Or(const LHS &L, const RHS &R)
Definition: PatternMatch.h:762
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1184
CastClass_match< OpTy, Instruction::BitCast > m_BitCast(const OpTy &Op)
Matches BitCast.
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...
Value * CreateSelect(Value *C, Value *True, Value *False, const Twine &Name="", Instruction *MDFrom=nullptr)
Definition: IRBuilder.h:2057
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:285
bool isOneValue() const
Determine if this is a value of 1.
Definition: APInt.h:410
APInt ssub_ov(const APInt &RHS, bool &Overflow) const
Definition: APInt.cpp:1887
cst_pred_ty< is_all_ones > m_AllOnes()
Match an integer or vector with all bits set.
Definition: PatternMatch.h:308
static APInt getOneBitSet(unsigned numBits, unsigned BitNo)
Return an APInt with exactly one bit set in the result.
Definition: APInt.h:587
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:501
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:1192
Value * CreateNeg(Value *V, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1343
This instruction compares its operands according to the predicate given to the constructor.
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:709
static Constant * getBinOpIdentity(unsigned Opcode, Type *Ty, bool AllowRHSConstant=false)
Return the identity constant for a binary opcode.
Definition: Constants.cpp:2316
CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF, bool Ordered=false)
Return the canonical comparison predicate for the specified minimum/maximum flavor.
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:73
Class to represent integer types.
Definition: DerivedTypes.h:39
const Value * getCondition() const
bool isCast() const
Definition: Instruction.h:133
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.
signed greater than
Definition: InstrTypes.h:736
CastClass_match< OpTy, Instruction::SExt > m_SExt(const OpTy &Op)
Matches SExt.
Floating point maxnum.
static Value * createMinMax(InstCombiner::BuilderTy &Builder, SelectPatternFlavor SPF, Value *A, Value *B)
0 0 1 0 True if ordered and greater than
Definition: InstrTypes.h:713
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...
unsigned getNumOperands() const
Definition: User.h:191
SelectPatternFlavor Flavor
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type...
Definition: Type.cpp:129
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:841
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:63
Provides information about what library functions are available for the current target.
signed less than
Definition: InstrTypes.h:738
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:1646
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:631
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1292
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:587
bool isCommutative() const
Return true if the instruction is commutative:
Definition: Instruction.h:488
Instruction * visitSelectInst(SelectInst &SI)
void setPredicate(Predicate P)
Set the predicate for this instruction to the specified value.
Definition: InstrTypes.h:789
OverflowingBinaryOp_match< LHS, RHS, Instruction::Add, OverflowingBinaryOperator::NoSignedWrap > m_NSWAdd(const LHS &L, const RHS &R)
Definition: PatternMatch.h:819
void setOperand(unsigned i, Value *Val)
Definition: User.h:174
unsigned logBase2() const
Definition: APInt.h:1747
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:940
unsigned getVectorNumElements() const
Definition: DerivedTypes.h:493
bool isIntPredicate() const
Definition: InstrTypes.h:802
Class to represent vector types.
Definition: DerivedTypes.h:424
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:55
Class for arbitrary precision integers.
Definition: APInt.h:69
bool ule(const APInt &RHS) const
Unsigned less or equal comparison.
Definition: APInt.h:1222
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:463
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:1308
iterator_range< user_iterator > users()
Definition: Value.h:399
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1539
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1138
const Value * getFalseValue() const
void setCondition(Value *V)
static APInt getSelectFoldableConstant(BinaryOperator *I)
For the same transformation as the previous function, return the identity constant that goes into the...
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 greather than comparison.
Definition: APInt.h:1254
Predicate getPredicate() const
Return the predicate for this instruction.
Definition: InstrTypes.h:784
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:696
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).
void setTrueValue(Value *V)
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:175
static bool isMinOrMax(SelectPatternFlavor SPF)
When implementing this min/max pattern as fcmp; select, does the fcmp have to be ordered?
unsigned greater or equal
Definition: InstrTypes.h:733
static bool isUnordered(Predicate predicate)
Determine if the predicate is an unordered operation.
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
bool isEquality() const
Return true if this predicate is either EQ or NE.
#define I(x, y, z)
Definition: MD5.cpp:58
MaxMin_match< ICmpInst, LHS, RHS, smax_pred_ty > m_SMax(const LHS &L, const RHS &R)
static BinaryOperator * CreateFNegFMF(Value *Op, BinaryOperator *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:260
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:332
void setFalseValue(Value *V)
Signed minimum.
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:741
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1199
InstTy * Insert(InstTy *I, const Twine &Name="") const
Insert and return the specified instruction.
Definition: IRBuilder.h:793
bool isFPOrFPVectorTy() const
Return true if this is a FP type or a vector of FP.
Definition: Type.h:184
bool isOneValue() const
Returns true if the value is one.
Definition: Constants.cpp:125
Value * CreateCast(Instruction::CastOps Op, Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1804
static GetElementPtrInst * CreateInBounds(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Create an "inbounds" getelementptr.
Definition: Instructions.h:933
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:544
0 0 0 1 True if ordered and equal
Definition: InstrTypes.h:712
LLVM Value Representation.
Definition: Value.h:72
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:354
std::underlying_type< E >::type 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
void setFastMathFlags(FastMathFlags NewFMF)
Set the fast-math flags to be used with generated fp-math operators.
Definition: IRBuilder.h:219
void moveBefore(Instruction *MovePos)
Unlink this instruction from its current basic block and insert it into the basic block that MovePos ...
Definition: Instruction.cpp:86
Value * CreateLShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1159
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:412
Convenience struct for specifying and reasoning about fast-math flags.
Definition: Operator.h:159
unsigned greater than
Definition: InstrTypes.h:732
Predicate getSwappedPredicate() const
For example, EQ->EQ, SLE->SGE, ULT->UGT, OEQ->OEQ, ULE->UGE, OLT->OGT, etc.
Definition: InstrTypes.h:824
static APInt getNullValue(unsigned numBits)
Get the &#39;0&#39; value.
Definition: APInt.h:568
specific_intval m_SpecificInt(uint64_t V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:578
cstfp_pred_ty< is_any_zero_fp > m_AnyZeroFP()
Match a floating-point negative zero or positive zero.
Definition: PatternMatch.h:435
0 0 1 1 True if ordered and greater than or equal
Definition: InstrTypes.h:714
static Constant * get(ArrayRef< Constant *> V)
Definition: Constants.cpp:1088
Value * CreateFNeg(Value *V, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1361
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:478
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:405
IntegerType * Int32Ty
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:43
const BasicBlock * getParent() const
Definition: Instruction.h:66
CmpClass_match< LHS, RHS, ICmpInst, ICmpInst::Predicate > m_ICmp(ICmpInst::Predicate &Pred, const LHS &L, const RHS &R)