LLVM  10.0.0svn
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 sgt x, C), lshr (X, Y), ashr (X, Y)); iff C s>= -1
536 /// (select (icmp slt x, C), ashr (X, Y), lshr (X, Y)); iff C s>= 0
537 /// into:
538 /// ashr (X, Y)
539 static Value *foldSelectICmpLshrAshr(const ICmpInst *IC, Value *TrueVal,
540  Value *FalseVal,
541  InstCombiner::BuilderTy &Builder) {
542  ICmpInst::Predicate Pred = IC->getPredicate();
543  Value *CmpLHS = IC->getOperand(0);
544  Value *CmpRHS = IC->getOperand(1);
545  if (!CmpRHS->getType()->isIntOrIntVectorTy())
546  return nullptr;
547 
548  Value *X, *Y;
549  unsigned Bitwidth = CmpRHS->getType()->getScalarSizeInBits();
550  if ((Pred != ICmpInst::ICMP_SGT ||
551  !match(CmpRHS,
552  m_SpecificInt_ICMP(ICmpInst::ICMP_SGE, APInt(Bitwidth, -1)))) &&
553  (Pred != ICmpInst::ICMP_SLT ||
554  !match(CmpRHS,
556  return nullptr;
557 
558  // Canonicalize so that ashr is in FalseVal.
559  if (Pred == ICmpInst::ICMP_SLT)
560  std::swap(TrueVal, FalseVal);
561 
562  if (match(TrueVal, m_LShr(m_Value(X), m_Value(Y))) &&
563  match(FalseVal, m_AShr(m_Specific(X), m_Specific(Y))) &&
564  match(CmpLHS, m_Specific(X))) {
565  const auto *Ashr = cast<Instruction>(FalseVal);
566  // if lshr is not exact and ashr is, this new ashr must not be exact.
567  bool IsExact = Ashr->isExact() && cast<Instruction>(TrueVal)->isExact();
568  return Builder.CreateAShr(X, Y, IC->getName(), IsExact);
569  }
570 
571  return nullptr;
572 }
573 
574 /// We want to turn:
575 /// (select (icmp eq (and X, C1), 0), Y, (or Y, C2))
576 /// into:
577 /// (or (shl (and X, C1), C3), Y)
578 /// iff:
579 /// C1 and C2 are both powers of 2
580 /// where:
581 /// C3 = Log(C2) - Log(C1)
582 ///
583 /// This transform handles cases where:
584 /// 1. The icmp predicate is inverted
585 /// 2. The select operands are reversed
586 /// 3. The magnitude of C2 and C1 are flipped
587 static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal,
588  Value *FalseVal,
589  InstCombiner::BuilderTy &Builder) {
590  // Only handle integer compares. Also, if this is a vector select, we need a
591  // vector compare.
592  if (!TrueVal->getType()->isIntOrIntVectorTy() ||
593  TrueVal->getType()->isVectorTy() != IC->getType()->isVectorTy())
594  return nullptr;
595 
596  Value *CmpLHS = IC->getOperand(0);
597  Value *CmpRHS = IC->getOperand(1);
598 
599  Value *V;
600  unsigned C1Log;
601  bool IsEqualZero;
602  bool NeedAnd = false;
603  if (IC->isEquality()) {
604  if (!match(CmpRHS, m_Zero()))
605  return nullptr;
606 
607  const APInt *C1;
608  if (!match(CmpLHS, m_And(m_Value(), m_Power2(C1))))
609  return nullptr;
610 
611  V = CmpLHS;
612  C1Log = C1->logBase2();
613  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ;
614  } else if (IC->getPredicate() == ICmpInst::ICMP_SLT ||
615  IC->getPredicate() == ICmpInst::ICMP_SGT) {
616  // We also need to recognize (icmp slt (trunc (X)), 0) and
617  // (icmp sgt (trunc (X)), -1).
618  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_SGT;
619  if ((IsEqualZero && !match(CmpRHS, m_AllOnes())) ||
620  (!IsEqualZero && !match(CmpRHS, m_Zero())))
621  return nullptr;
622 
623  if (!match(CmpLHS, m_OneUse(m_Trunc(m_Value(V)))))
624  return nullptr;
625 
626  C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1;
627  NeedAnd = true;
628  } else {
629  return nullptr;
630  }
631 
632  const APInt *C2;
633  bool OrOnTrueVal = false;
634  bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)));
635  if (!OrOnFalseVal)
636  OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2)));
637 
638  if (!OrOnFalseVal && !OrOnTrueVal)
639  return nullptr;
640 
641  Value *Y = OrOnFalseVal ? TrueVal : FalseVal;
642 
643  unsigned C2Log = C2->logBase2();
644 
645  bool NeedXor = (!IsEqualZero && OrOnFalseVal) || (IsEqualZero && OrOnTrueVal);
646  bool NeedShift = C1Log != C2Log;
647  bool NeedZExtTrunc = Y->getType()->getScalarSizeInBits() !=
649 
650  // Make sure we don't create more instructions than we save.
651  Value *Or = OrOnFalseVal ? FalseVal : TrueVal;
652  if ((NeedShift + NeedXor + NeedZExtTrunc) >
653  (IC->hasOneUse() + Or->hasOneUse()))
654  return nullptr;
655 
656  if (NeedAnd) {
657  // Insert the AND instruction on the input to the truncate.
659  V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), C1));
660  }
661 
662  if (C2Log > C1Log) {
663  V = Builder.CreateZExtOrTrunc(V, Y->getType());
664  V = Builder.CreateShl(V, C2Log - C1Log);
665  } else if (C1Log > C2Log) {
666  V = Builder.CreateLShr(V, C1Log - C2Log);
667  V = Builder.CreateZExtOrTrunc(V, Y->getType());
668  } else
669  V = Builder.CreateZExtOrTrunc(V, Y->getType());
670 
671  if (NeedXor)
672  V = Builder.CreateXor(V, *C2);
673 
674  return Builder.CreateOr(V, Y);
675 }
676 
677 /// Transform patterns such as (a > b) ? a - b : 0 into usub.sat(a, b).
678 /// There are 8 commuted/swapped variants of this pattern.
679 /// TODO: Also support a - UMIN(a,b) patterns.
681  const Value *TrueVal,
682  const Value *FalseVal,
683  InstCombiner::BuilderTy &Builder) {
684  ICmpInst::Predicate Pred = ICI->getPredicate();
685  if (!ICmpInst::isUnsigned(Pred))
686  return nullptr;
687 
688  // (b > a) ? 0 : a - b -> (b <= a) ? a - b : 0
689  if (match(TrueVal, m_Zero())) {
690  Pred = ICmpInst::getInversePredicate(Pred);
691  std::swap(TrueVal, FalseVal);
692  }
693  if (!match(FalseVal, m_Zero()))
694  return nullptr;
695 
696  Value *A = ICI->getOperand(0);
697  Value *B = ICI->getOperand(1);
698  if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_ULT) {
699  // (b < a) ? a - b : 0 -> (a > b) ? a - b : 0
700  std::swap(A, B);
701  Pred = ICmpInst::getSwappedPredicate(Pred);
702  }
703 
704  assert((Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_UGT) &&
705  "Unexpected isUnsigned predicate!");
706 
707  // Account for swapped form of subtraction: ((a > b) ? b - a : 0).
708  bool IsNegative = false;
709  if (match(TrueVal, m_Sub(m_Specific(B), m_Specific(A))))
710  IsNegative = true;
711  else if (!match(TrueVal, m_Sub(m_Specific(A), m_Specific(B))))
712  return nullptr;
713 
714  // If sub is used anywhere else, we wouldn't be able to eliminate it
715  // afterwards.
716  if (!TrueVal->hasOneUse())
717  return nullptr;
718 
719  // (a > b) ? a - b : 0 -> usub.sat(a, b)
720  // (a > b) ? b - a : 0 -> -usub.sat(a, b)
721  Value *Result = Builder.CreateBinaryIntrinsic(Intrinsic::usub_sat, A, B);
722  if (IsNegative)
723  Result = Builder.CreateNeg(Result);
724  return Result;
725 }
726 
727 static Value *canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal,
728  InstCombiner::BuilderTy &Builder) {
729  if (!Cmp->hasOneUse())
730  return nullptr;
731 
732  // Match unsigned saturated add with constant.
733  Value *Cmp0 = Cmp->getOperand(0);
734  Value *Cmp1 = Cmp->getOperand(1);
735  ICmpInst::Predicate Pred = Cmp->getPredicate();
736  Value *X;
737  const APInt *C, *CmpC;
738  if (Pred == ICmpInst::ICMP_ULT &&
739  match(TVal, m_Add(m_Value(X), m_APInt(C))) && X == Cmp0 &&
740  match(FVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) && *CmpC == ~*C) {
741  // (X u< ~C) ? (X + C) : -1 --> uadd.sat(X, C)
742  return Builder.CreateBinaryIntrinsic(
743  Intrinsic::uadd_sat, X, ConstantInt::get(X->getType(), *C));
744  }
745 
746  // Match unsigned saturated add of 2 variables with an unnecessary 'not'.
747  // There are 8 commuted variants.
748  // Canonicalize -1 (saturated result) to true value of the select. Just
749  // swapping the compare operands is legal, because the selected value is the
750  // same in case of equality, so we can interchange u< and u<=.
751  if (match(FVal, m_AllOnes())) {
752  std::swap(TVal, FVal);
753  std::swap(Cmp0, Cmp1);
754  }
755  if (!match(TVal, m_AllOnes()))
756  return nullptr;
757 
758  // Canonicalize predicate to 'ULT'.
759  if (Pred == ICmpInst::ICMP_UGT) {
760  Pred = ICmpInst::ICMP_ULT;
761  std::swap(Cmp0, Cmp1);
762  }
763  if (Pred != ICmpInst::ICMP_ULT)
764  return nullptr;
765 
766  // Match unsigned saturated add of 2 variables with an unnecessary 'not'.
767  Value *Y;
768  if (match(Cmp0, m_Not(m_Value(X))) &&
769  match(FVal, m_c_Add(m_Specific(X), m_Value(Y))) && Y == Cmp1) {
770  // (~X u< Y) ? -1 : (X + Y) --> uadd.sat(X, Y)
771  // (~X u< Y) ? -1 : (Y + X) --> uadd.sat(X, Y)
772  return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, X, Y);
773  }
774  // The 'not' op may be included in the sum but not the compare.
775  X = Cmp0;
776  Y = Cmp1;
777  if (match(FVal, m_c_Add(m_Not(m_Specific(X)), m_Specific(Y)))) {
778  // (X u< Y) ? -1 : (~X + Y) --> uadd.sat(~X, Y)
779  // (X u< Y) ? -1 : (Y + ~X) --> uadd.sat(Y, ~X)
780  BinaryOperator *BO = cast<BinaryOperator>(FVal);
781  return Builder.CreateBinaryIntrinsic(
782  Intrinsic::uadd_sat, BO->getOperand(0), BO->getOperand(1));
783  }
784 
785  return nullptr;
786 }
787 
788 /// Fold the following code sequence:
789 /// \code
790 /// int a = ctlz(x & -x);
791 // x ? 31 - a : a;
792 /// \code
793 ///
794 /// into:
795 /// cttz(x)
796 static Instruction *foldSelectCtlzToCttz(ICmpInst *ICI, Value *TrueVal,
797  Value *FalseVal,
798  InstCombiner::BuilderTy &Builder) {
799  unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits();
800  if (!ICI->isEquality() || !match(ICI->getOperand(1), m_Zero()))
801  return nullptr;
802 
803  if (ICI->getPredicate() == ICmpInst::ICMP_NE)
804  std::swap(TrueVal, FalseVal);
805 
806  if (!match(FalseVal,
807  m_Xor(m_Deferred(TrueVal), m_SpecificInt(BitWidth - 1))))
808  return nullptr;
809 
810  if (!match(TrueVal, m_Intrinsic<Intrinsic::ctlz>()))
811  return nullptr;
812 
813  Value *X = ICI->getOperand(0);
814  auto *II = cast<IntrinsicInst>(TrueVal);
815  if (!match(II->getOperand(0), m_c_And(m_Specific(X), m_Neg(m_Specific(X)))))
816  return nullptr;
817 
818  Function *F = Intrinsic::getDeclaration(II->getModule(), Intrinsic::cttz,
819  II->getType());
820  return CallInst::Create(F, {X, II->getArgOperand(1)});
821 }
822 
823 /// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single
824 /// call to cttz/ctlz with flag 'is_zero_undef' cleared.
825 ///
826 /// For example, we can fold the following code sequence:
827 /// \code
828 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
829 /// %1 = icmp ne i32 %x, 0
830 /// %2 = select i1 %1, i32 %0, i32 32
831 /// \code
832 ///
833 /// into:
834 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
835 static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
836  InstCombiner::BuilderTy &Builder) {
837  ICmpInst::Predicate Pred = ICI->getPredicate();
838  Value *CmpLHS = ICI->getOperand(0);
839  Value *CmpRHS = ICI->getOperand(1);
840 
841  // Check if the condition value compares a value for equality against zero.
842  if (!ICI->isEquality() || !match(CmpRHS, m_Zero()))
843  return nullptr;
844 
845  Value *Count = FalseVal;
846  Value *ValueOnZero = TrueVal;
847  if (Pred == ICmpInst::ICMP_NE)
848  std::swap(Count, ValueOnZero);
849 
850  // Skip zero extend/truncate.
851  Value *V = nullptr;
852  if (match(Count, m_ZExt(m_Value(V))) ||
853  match(Count, m_Trunc(m_Value(V))))
854  Count = V;
855 
856  // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
857  // input to the cttz/ctlz is used as LHS for the compare instruction.
858  if (!match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) &&
859  !match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS))))
860  return nullptr;
861 
862  IntrinsicInst *II = cast<IntrinsicInst>(Count);
863 
864  // Check if the value propagated on zero is a constant number equal to the
865  // sizeof in bits of 'Count'.
866  unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits();
867  if (match(ValueOnZero, m_SpecificInt(SizeOfInBits))) {
868  // Explicitly clear the 'undef_on_zero' flag.
869  IntrinsicInst *NewI = cast<IntrinsicInst>(II->clone());
871  Builder.Insert(NewI);
872  return Builder.CreateZExtOrTrunc(NewI, ValueOnZero->getType());
873  }
874 
875  // If the ValueOnZero is not the bitwidth, we can at least make use of the
876  // fact that the cttz/ctlz result will not be used if the input is zero, so
877  // it's okay to relax it to undef for that case.
878  if (II->hasOneUse() && !match(II->getArgOperand(1), m_One()))
880 
881  return nullptr;
882 }
883 
884 /// Return true if we find and adjust an icmp+select pattern where the compare
885 /// is with a constant that can be incremented or decremented to match the
886 /// minimum or maximum idiom.
887 static bool adjustMinMax(SelectInst &Sel, ICmpInst &Cmp) {
888  ICmpInst::Predicate Pred = Cmp.getPredicate();
889  Value *CmpLHS = Cmp.getOperand(0);
890  Value *CmpRHS = Cmp.getOperand(1);
891  Value *TrueVal = Sel.getTrueValue();
892  Value *FalseVal = Sel.getFalseValue();
893 
894  // We may move or edit the compare, so make sure the select is the only user.
895  const APInt *CmpC;
896  if (!Cmp.hasOneUse() || !match(CmpRHS, m_APInt(CmpC)))
897  return false;
898 
899  // These transforms only work for selects of integers or vector selects of
900  // integer vectors.
901  Type *SelTy = Sel.getType();
902  auto *SelEltTy = dyn_cast<IntegerType>(SelTy->getScalarType());
903  if (!SelEltTy || SelTy->isVectorTy() != Cmp.getType()->isVectorTy())
904  return false;
905 
906  Constant *AdjustedRHS;
907  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT)
908  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC + 1);
909  else if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT)
910  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC - 1);
911  else
912  return false;
913 
914  // X > C ? X : C+1 --> X < C+1 ? C+1 : X
915  // X < C ? X : C-1 --> X > C-1 ? C-1 : X
916  if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
917  (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
918  ; // Nothing to do here. Values match without any sign/zero extension.
919  }
920  // Types do not match. Instead of calculating this with mixed types, promote
921  // all to the larger type. This enables scalar evolution to analyze this
922  // expression.
923  else if (CmpRHS->getType()->getScalarSizeInBits() < SelEltTy->getBitWidth()) {
924  Constant *SextRHS = ConstantExpr::getSExt(AdjustedRHS, SelTy);
925 
926  // X = sext x; x >s c ? X : C+1 --> X = sext x; X <s C+1 ? C+1 : X
927  // X = sext x; x <s c ? X : C-1 --> X = sext x; X >s C-1 ? C-1 : X
928  // X = sext x; x >u c ? X : C+1 --> X = sext x; X <u C+1 ? C+1 : X
929  // X = sext x; x <u c ? X : C-1 --> X = sext x; X >u C-1 ? C-1 : X
930  if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) && SextRHS == FalseVal) {
931  CmpLHS = TrueVal;
932  AdjustedRHS = SextRHS;
933  } else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) &&
934  SextRHS == TrueVal) {
935  CmpLHS = FalseVal;
936  AdjustedRHS = SextRHS;
937  } else if (Cmp.isUnsigned()) {
938  Constant *ZextRHS = ConstantExpr::getZExt(AdjustedRHS, SelTy);
939  // X = zext x; x >u c ? X : C+1 --> X = zext x; X <u C+1 ? C+1 : X
940  // X = zext x; x <u c ? X : C-1 --> X = zext x; X >u C-1 ? C-1 : X
941  // zext + signed compare cannot be changed:
942  // 0xff <s 0x00, but 0x00ff >s 0x0000
943  if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) && ZextRHS == FalseVal) {
944  CmpLHS = TrueVal;
945  AdjustedRHS = ZextRHS;
946  } else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) &&
947  ZextRHS == TrueVal) {
948  CmpLHS = FalseVal;
949  AdjustedRHS = ZextRHS;
950  } else {
951  return false;
952  }
953  } else {
954  return false;
955  }
956  } else {
957  return false;
958  }
959 
960  Pred = ICmpInst::getSwappedPredicate(Pred);
961  CmpRHS = AdjustedRHS;
962  std::swap(FalseVal, TrueVal);
963  Cmp.setPredicate(Pred);
964  Cmp.setOperand(0, CmpLHS);
965  Cmp.setOperand(1, CmpRHS);
966  Sel.setOperand(1, TrueVal);
967  Sel.setOperand(2, FalseVal);
968  Sel.swapProfMetadata();
969 
970  // Move the compare instruction right before the select instruction. Otherwise
971  // the sext/zext value may be defined after the compare instruction uses it.
972  Cmp.moveBefore(&Sel);
973 
974  return true;
975 }
976 
977 /// If this is an integer min/max (icmp + select) with a constant operand,
978 /// create the canonical icmp for the min/max operation and canonicalize the
979 /// constant to the 'false' operand of the select:
980 /// select (icmp Pred X, C1), C2, X --> select (icmp Pred' X, C2), X, C2
981 /// Note: if C1 != C2, this will change the icmp constant to the existing
982 /// constant operand of the select.
983 static Instruction *
984 canonicalizeMinMaxWithConstant(SelectInst &Sel, ICmpInst &Cmp,
985  InstCombiner::BuilderTy &Builder) {
986  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
987  return nullptr;
988 
989  // Canonicalize the compare predicate based on whether we have min or max.
990  Value *LHS, *RHS;
991  SelectPatternResult SPR = matchSelectPattern(&Sel, LHS, RHS);
993  return nullptr;
994 
995  // Is this already canonical?
996  ICmpInst::Predicate CanonicalPred = getMinMaxPred(SPR.Flavor);
997  if (Cmp.getOperand(0) == LHS && Cmp.getOperand(1) == RHS &&
998  Cmp.getPredicate() == CanonicalPred)
999  return nullptr;
1000 
1001  // Create the canonical compare and plug it into the select.
1002  Sel.setCondition(Builder.CreateICmp(CanonicalPred, LHS, RHS));
1003 
1004  // If the select operands did not change, we're done.
1005  if (Sel.getTrueValue() == LHS && Sel.getFalseValue() == RHS)
1006  return &Sel;
1007 
1008  // If we are swapping the select operands, swap the metadata too.
1009  assert(Sel.getTrueValue() == RHS && Sel.getFalseValue() == LHS &&
1010  "Unexpected results from matchSelectPattern");
1011  Sel.swapValues();
1012  Sel.swapProfMetadata();
1013  return &Sel;
1014 }
1015 
1016 /// There are many select variants for each of ABS/NABS.
1017 /// In matchSelectPattern(), there are different compare constants, compare
1018 /// predicates/operands and select operands.
1019 /// In isKnownNegation(), there are different formats of negated operands.
1020 /// Canonicalize all these variants to 1 pattern.
1021 /// This makes CSE more likely.
1022 static Instruction *canonicalizeAbsNabs(SelectInst &Sel, ICmpInst &Cmp,
1023  InstCombiner::BuilderTy &Builder) {
1024  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
1025  return nullptr;
1026 
1027  // Choose a sign-bit check for the compare (likely simpler for codegen).
1028  // ABS: (X <s 0) ? -X : X
1029  // NABS: (X <s 0) ? X : -X
1030  Value *LHS, *RHS;
1031  SelectPatternFlavor SPF = matchSelectPattern(&Sel, LHS, RHS).Flavor;
1032  if (SPF != SelectPatternFlavor::SPF_ABS &&
1034  return nullptr;
1035 
1036  Value *TVal = Sel.getTrueValue();
1037  Value *FVal = Sel.getFalseValue();
1038  assert(isKnownNegation(TVal, FVal) &&
1039  "Unexpected result from matchSelectPattern");
1040 
1041  // The compare may use the negated abs()/nabs() operand, or it may use
1042  // negation in non-canonical form such as: sub A, B.
1043  bool CmpUsesNegatedOp = match(Cmp.getOperand(0), m_Neg(m_Specific(TVal))) ||
1044  match(Cmp.getOperand(0), m_Neg(m_Specific(FVal)));
1045 
1046  bool CmpCanonicalized = !CmpUsesNegatedOp &&
1047  match(Cmp.getOperand(1), m_ZeroInt()) &&
1049  bool RHSCanonicalized = match(RHS, m_Neg(m_Specific(LHS)));
1050 
1051  // Is this already canonical?
1052  if (CmpCanonicalized && RHSCanonicalized)
1053  return nullptr;
1054 
1055  // If RHS is used by other instructions except compare and select, don't
1056  // canonicalize it to not increase the instruction count.
1057  if (!(RHS->hasOneUse() || (RHS->hasNUses(2) && CmpUsesNegatedOp)))
1058  return nullptr;
1059 
1060  // Create the canonical compare: icmp slt LHS 0.
1061  if (!CmpCanonicalized) {
1064  if (CmpUsesNegatedOp)
1065  Cmp.setOperand(0, LHS);
1066  }
1067 
1068  // Create the canonical RHS: RHS = sub (0, LHS).
1069  if (!RHSCanonicalized) {
1070  assert(RHS->hasOneUse() && "RHS use number is not right");
1071  RHS = Builder.CreateNeg(LHS);
1072  if (TVal == LHS) {
1073  Sel.setFalseValue(RHS);
1074  FVal = RHS;
1075  } else {
1076  Sel.setTrueValue(RHS);
1077  TVal = RHS;
1078  }
1079  }
1080 
1081  // If the select operands do not change, we're done.
1082  if (SPF == SelectPatternFlavor::SPF_NABS) {
1083  if (TVal == LHS)
1084  return &Sel;
1085  assert(FVal == LHS && "Unexpected results from matchSelectPattern");
1086  } else {
1087  if (FVal == LHS)
1088  return &Sel;
1089  assert(TVal == LHS && "Unexpected results from matchSelectPattern");
1090  }
1091 
1092  // We are swapping the select operands, so swap the metadata too.
1093  Sel.swapValues();
1094  Sel.swapProfMetadata();
1095  return &Sel;
1096 }
1097 
1098 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *ReplaceOp,
1099  const SimplifyQuery &Q) {
1100  // If this is a binary operator, try to simplify it with the replaced op
1101  // because we know Op and ReplaceOp are equivalant.
1102  // For example: V = X + 1, Op = X, ReplaceOp = 42
1103  // Simplifies as: add(42, 1) --> 43
1104  if (auto *BO = dyn_cast<BinaryOperator>(V)) {
1105  if (BO->getOperand(0) == Op)
1106  return SimplifyBinOp(BO->getOpcode(), ReplaceOp, BO->getOperand(1), Q);
1107  if (BO->getOperand(1) == Op)
1108  return SimplifyBinOp(BO->getOpcode(), BO->getOperand(0), ReplaceOp, Q);
1109  }
1110 
1111  return nullptr;
1112 }
1113 
1114 /// If we have a select with an equality comparison, then we know the value in
1115 /// one of the arms of the select. See if substituting this value into an arm
1116 /// and simplifying the result yields the same value as the other arm.
1117 ///
1118 /// To make this transform safe, we must drop poison-generating flags
1119 /// (nsw, etc) if we simplified to a binop because the select may be guarding
1120 /// that poison from propagating. If the existing binop already had no
1121 /// poison-generating flags, then this transform can be done by instsimplify.
1122 ///
1123 /// Consider:
1124 /// %cmp = icmp eq i32 %x, 2147483647
1125 /// %add = add nsw i32 %x, 1
1126 /// %sel = select i1 %cmp, i32 -2147483648, i32 %add
1127 ///
1128 /// We can't replace %sel with %add unless we strip away the flags.
1129 /// TODO: Wrapping flags could be preserved in some cases with better analysis.
1130 static Value *foldSelectValueEquivalence(SelectInst &Sel, ICmpInst &Cmp,
1131  const SimplifyQuery &Q) {
1132  if (!Cmp.isEquality())
1133  return nullptr;
1134 
1135  // Canonicalize the pattern to ICMP_EQ by swapping the select operands.
1136  Value *TrueVal = Sel.getTrueValue(), *FalseVal = Sel.getFalseValue();
1137  if (Cmp.getPredicate() == ICmpInst::ICMP_NE)
1138  std::swap(TrueVal, FalseVal);
1139 
1140  // Try each equivalence substitution possibility.
1141  // We have an 'EQ' comparison, so the select's false value will propagate.
1142  // Example:
1143  // (X == 42) ? 43 : (X + 1) --> (X == 42) ? (X + 1) : (X + 1) --> X + 1
1144  // (X == 42) ? (X + 1) : 43 --> (X == 42) ? (42 + 1) : 43 --> 43
1145  Value *CmpLHS = Cmp.getOperand(0), *CmpRHS = Cmp.getOperand(1);
1146  if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q) == TrueVal ||
1147  simplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q) == TrueVal ||
1148  simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q) == FalseVal ||
1149  simplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q) == FalseVal) {
1150  if (auto *FalseInst = dyn_cast<Instruction>(FalseVal))
1151  FalseInst->dropPoisonGeneratingFlags();
1152  return FalseVal;
1153  }
1154  return nullptr;
1155 }
1156 
1157 // See if this is a pattern like:
1158 // %old_cmp1 = icmp slt i32 %x, C2
1159 // %old_replacement = select i1 %old_cmp1, i32 %target_low, i32 %target_high
1160 // %old_x_offseted = add i32 %x, C1
1161 // %old_cmp0 = icmp ult i32 %old_x_offseted, C0
1162 // %r = select i1 %old_cmp0, i32 %x, i32 %old_replacement
1163 // This can be rewritten as more canonical pattern:
1164 // %new_cmp1 = icmp slt i32 %x, -C1
1165 // %new_cmp2 = icmp sge i32 %x, C0-C1
1166 // %new_clamped_low = select i1 %new_cmp1, i32 %target_low, i32 %x
1167 // %r = select i1 %new_cmp2, i32 %target_high, i32 %new_clamped_low
1168 // Iff -C1 s<= C2 s<= C0-C1
1169 // Also ULT predicate can also be UGT iff C0 != -1 (+invert result)
1170 // SLT predicate can also be SGT iff C2 != INT_MAX (+invert res.)
1171 static Instruction *canonicalizeClampLike(SelectInst &Sel0, ICmpInst &Cmp0,
1172  InstCombiner::BuilderTy &Builder) {
1173  Value *X = Sel0.getTrueValue();
1174  Value *Sel1 = Sel0.getFalseValue();
1175 
1176  // First match the condition of the outermost select.
1177  // Said condition must be one-use.
1178  if (!Cmp0.hasOneUse())
1179  return nullptr;
1180  Value *Cmp00 = Cmp0.getOperand(0);
1181  Constant *C0;
1182  if (!match(Cmp0.getOperand(1),
1184  return nullptr;
1185  // Canonicalize Cmp0 into the form we expect.
1186  // FIXME: we shouldn't care about lanes that are 'undef' in the end?
1187  switch (Cmp0.getPredicate()) {
1188  case ICmpInst::Predicate::ICMP_ULT:
1189  break; // Great!
1190  case ICmpInst::Predicate::ICMP_ULE:
1191  // We'd have to increment C0 by one, and for that it must not have all-ones
1192  // element, but then it would have been canonicalized to 'ult' before
1193  // we get here. So we can't do anything useful with 'ule'.
1194  return nullptr;
1195  case ICmpInst::Predicate::ICMP_UGT:
1196  // We want to canonicalize it to 'ult', so we'll need to increment C0,
1197  // which again means it must not have any all-ones elements.
1198  if (!match(C0,
1199  m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_NE,
1201  C0->getType()->getScalarSizeInBits()))))
1202  return nullptr; // Can't do, have all-ones element[s].
1203  C0 = AddOne(C0);
1204  std::swap(X, Sel1);
1205  break;
1206  case ICmpInst::Predicate::ICMP_UGE:
1207  // The only way we'd get this predicate if this `icmp` has extra uses,
1208  // but then we won't be able to do this fold.
1209  return nullptr;
1210  default:
1211  return nullptr; // Unknown predicate.
1212  }
1213 
1214  // Now that we've canonicalized the ICmp, we know the X we expect;
1215  // the select in other hand should be one-use.
1216  if (!Sel1->hasOneUse())
1217  return nullptr;
1218 
1219  // We now can finish matching the condition of the outermost select:
1220  // it should either be the X itself, or an addition of some constant to X.
1221  Constant *C1;
1222  if (Cmp00 == X)
1223  C1 = ConstantInt::getNullValue(Sel0.getType());
1224  else if (!match(Cmp00,
1225  m_Add(m_Specific(X),
1227  return nullptr;
1228 
1229  Value *Cmp1;
1230  ICmpInst::Predicate Pred1;
1231  Constant *C2;
1232  Value *ReplacementLow, *ReplacementHigh;
1233  if (!match(Sel1, m_Select(m_Value(Cmp1), m_Value(ReplacementLow),
1234  m_Value(ReplacementHigh))) ||
1235  !match(Cmp1,
1236  m_ICmp(Pred1, m_Specific(X),
1238  return nullptr;
1239 
1240  if (!Cmp1->hasOneUse() && (Cmp00 == X || !Cmp00->hasOneUse()))
1241  return nullptr; // Not enough one-use instructions for the fold.
1242  // FIXME: this restriction could be relaxed if Cmp1 can be reused as one of
1243  // two comparisons we'll need to build.
1244 
1245  // Canonicalize Cmp1 into the form we expect.
1246  // FIXME: we shouldn't care about lanes that are 'undef' in the end?
1247  switch (Pred1) {
1248  case ICmpInst::Predicate::ICMP_SLT:
1249  break;
1250  case ICmpInst::Predicate::ICMP_SLE:
1251  // We'd have to increment C2 by one, and for that it must not have signed
1252  // max element, but then it would have been canonicalized to 'slt' before
1253  // we get here. So we can't do anything useful with 'sle'.
1254  return nullptr;
1255  case ICmpInst::Predicate::ICMP_SGT:
1256  // We want to canonicalize it to 'slt', so we'll need to increment C2,
1257  // which again means it must not have any signed max elements.
1258  if (!match(C2,
1259  m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_NE,
1261  C2->getType()->getScalarSizeInBits()))))
1262  return nullptr; // Can't do, have signed max element[s].
1263  C2 = AddOne(C2);
1265  case ICmpInst::Predicate::ICMP_SGE:
1266  // Also non-canonical, but here we don't need to change C2,
1267  // so we don't have any restrictions on C2, so we can just handle it.
1268  std::swap(ReplacementLow, ReplacementHigh);
1269  break;
1270  default:
1271  return nullptr; // Unknown predicate.
1272  }
1273 
1274  // The thresholds of this clamp-like pattern.
1275  auto *ThresholdLowIncl = ConstantExpr::getNeg(C1);
1276  auto *ThresholdHighExcl = ConstantExpr::getSub(C0, C1);
1277 
1278  // The fold has a precondition 1: C2 s>= ThresholdLow
1279  auto *Precond1 = ConstantExpr::getICmp(ICmpInst::Predicate::ICMP_SGE, C2,
1280  ThresholdLowIncl);
1281  if (!match(Precond1, m_One()))
1282  return nullptr;
1283  // The fold has a precondition 2: C2 s<= ThresholdHigh
1284  auto *Precond2 = ConstantExpr::getICmp(ICmpInst::Predicate::ICMP_SLE, C2,
1285  ThresholdHighExcl);
1286  if (!match(Precond2, m_One()))
1287  return nullptr;
1288 
1289  // All good, finally emit the new pattern.
1290  Value *ShouldReplaceLow = Builder.CreateICmpSLT(X, ThresholdLowIncl);
1291  Value *ShouldReplaceHigh = Builder.CreateICmpSGE(X, ThresholdHighExcl);
1292  Value *MaybeReplacedLow =
1293  Builder.CreateSelect(ShouldReplaceLow, ReplacementLow, X);
1294  Instruction *MaybeReplacedHigh =
1295  SelectInst::Create(ShouldReplaceHigh, ReplacementHigh, MaybeReplacedLow);
1296 
1297  return MaybeReplacedHigh;
1298 }
1299 
1300 // If we have
1301 // %cmp = icmp [canonical predicate] i32 %x, C0
1302 // %r = select i1 %cmp, i32 %y, i32 C1
1303 // Where C0 != C1 and %x may be different from %y, see if the constant that we
1304 // will have if we flip the strictness of the predicate (i.e. without changing
1305 // the result) is identical to the C1 in select. If it matches we can change
1306 // original comparison to one with swapped predicate, reuse the constant,
1307 // and swap the hands of select.
1308 static Instruction *
1309 tryToReuseConstantFromSelectInComparison(SelectInst &Sel, ICmpInst &Cmp,
1310  InstCombiner::BuilderTy &Builder) {
1311  ICmpInst::Predicate Pred;
1312  Value *X;
1313  Constant *C0;
1314  if (!match(&Cmp, m_OneUse(m_ICmp(
1315  Pred, m_Value(X),
1317  return nullptr;
1318 
1319  // If comparison predicate is non-relational, we won't be able to do anything.
1320  if (ICmpInst::isEquality(Pred))
1321  return nullptr;
1322 
1323  // If comparison predicate is non-canonical, then we certainly won't be able
1324  // to make it canonical; canonicalizeCmpWithConstant() already tried.
1325  if (!isCanonicalPredicate(Pred))
1326  return nullptr;
1327 
1328  // If the [input] type of comparison and select type are different, lets abort
1329  // for now. We could try to compare constants with trunc/[zs]ext though.
1330  if (C0->getType() != Sel.getType())
1331  return nullptr;
1332 
1333  // FIXME: are there any magic icmp predicate+constant pairs we must not touch?
1334 
1335  Value *SelVal0, *SelVal1; // We do not care which one is from where.
1336  match(&Sel, m_Select(m_Value(), m_Value(SelVal0), m_Value(SelVal1)));
1337  // At least one of these values we are selecting between must be a constant
1338  // else we'll never succeed.
1339  if (!match(SelVal0, m_AnyIntegralConstant()) &&
1340  !match(SelVal1, m_AnyIntegralConstant()))
1341  return nullptr;
1342 
1343  // Does this constant C match any of the `select` values?
1344  auto MatchesSelectValue = [SelVal0, SelVal1](Constant *C) {
1345  return C->isElementWiseEqual(SelVal0) || C->isElementWiseEqual(SelVal1);
1346  };
1347 
1348  // If C0 *already* matches true/false value of select, we are done.
1349  if (MatchesSelectValue(C0))
1350  return nullptr;
1351 
1352  // Check the constant we'd have with flipped-strictness predicate.
1353  auto FlippedStrictness = getFlippedStrictnessPredicateAndConstant(Pred, C0);
1354  if (!FlippedStrictness)
1355  return nullptr;
1356 
1357  // If said constant doesn't match either, then there is no hope,
1358  if (!MatchesSelectValue(FlippedStrictness->second))
1359  return nullptr;
1360 
1361  // It matched! Lets insert the new comparison just before select.
1362  InstCombiner::BuilderTy::InsertPointGuard Guard(Builder);
1363  Builder.SetInsertPoint(&Sel);
1364 
1365  Pred = ICmpInst::getSwappedPredicate(Pred); // Yes, swapped.
1366  Value *NewCmp = Builder.CreateICmp(Pred, X, FlippedStrictness->second,
1367  Cmp.getName() + ".inv");
1368  Sel.setCondition(NewCmp);
1369  Sel.swapValues();
1370  Sel.swapProfMetadata();
1371 
1372  return &Sel;
1373 }
1374 
1375 /// Visit a SelectInst that has an ICmpInst as its first operand.
1376 Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI,
1377  ICmpInst *ICI) {
1378  if (Value *V = foldSelectValueEquivalence(SI, *ICI, SQ))
1379  return replaceInstUsesWith(SI, V);
1380 
1381  if (Instruction *NewSel = canonicalizeMinMaxWithConstant(SI, *ICI, Builder))
1382  return NewSel;
1383 
1384  if (Instruction *NewAbs = canonicalizeAbsNabs(SI, *ICI, Builder))
1385  return NewAbs;
1386 
1387  if (Instruction *NewAbs = canonicalizeClampLike(SI, *ICI, Builder))
1388  return NewAbs;
1389 
1390  if (Instruction *NewSel =
1391  tryToReuseConstantFromSelectInComparison(SI, *ICI, Builder))
1392  return NewSel;
1393 
1394  bool Changed = adjustMinMax(SI, *ICI);
1395 
1396  if (Value *V = foldSelectICmpAnd(SI, ICI, Builder))
1397  return replaceInstUsesWith(SI, V);
1398 
1399  // NOTE: if we wanted to, this is where to detect integer MIN/MAX
1400  Value *TrueVal = SI.getTrueValue();
1401  Value *FalseVal = SI.getFalseValue();
1402  ICmpInst::Predicate Pred = ICI->getPredicate();
1403  Value *CmpLHS = ICI->getOperand(0);
1404  Value *CmpRHS = ICI->getOperand(1);
1405  if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
1406  if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
1407  // Transform (X == C) ? X : Y -> (X == C) ? C : Y
1408  SI.setOperand(1, CmpRHS);
1409  Changed = true;
1410  } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
1411  // Transform (X != C) ? Y : X -> (X != C) ? Y : C
1412  SI.setOperand(2, CmpRHS);
1413  Changed = true;
1414  }
1415  }
1416 
1417  // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring
1418  // decomposeBitTestICmp() might help.
1419  {
1420  unsigned BitWidth =
1421  DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
1422  APInt MinSignedValue = APInt::getSignedMinValue(BitWidth);
1423  Value *X;
1424  const APInt *Y, *C;
1425  bool TrueWhenUnset;
1426  bool IsBitTest = false;
1427  if (ICmpInst::isEquality(Pred) &&
1428  match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) &&
1429  match(CmpRHS, m_Zero())) {
1430  IsBitTest = true;
1431  TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
1432  } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
1433  X = CmpLHS;
1434  Y = &MinSignedValue;
1435  IsBitTest = true;
1436  TrueWhenUnset = false;
1437  } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
1438  X = CmpLHS;
1439  Y = &MinSignedValue;
1440  IsBitTest = true;
1441  TrueWhenUnset = true;
1442  }
1443  if (IsBitTest) {
1444  Value *V = nullptr;
1445  // (X & Y) == 0 ? X : X ^ Y --> X & ~Y
1446  if (TrueWhenUnset && TrueVal == X &&
1447  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1448  V = Builder.CreateAnd(X, ~(*Y));
1449  // (X & Y) != 0 ? X ^ Y : X --> X & ~Y
1450  else if (!TrueWhenUnset && FalseVal == X &&
1451  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1452  V = Builder.CreateAnd(X, ~(*Y));
1453  // (X & Y) == 0 ? X ^ Y : X --> X | Y
1454  else if (TrueWhenUnset && FalseVal == X &&
1455  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1456  V = Builder.CreateOr(X, *Y);
1457  // (X & Y) != 0 ? X : X ^ Y --> X | Y
1458  else if (!TrueWhenUnset && TrueVal == X &&
1459  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
1460  V = Builder.CreateOr(X, *Y);
1461 
1462  if (V)
1463  return replaceInstUsesWith(SI, V);
1464  }
1465  }
1466 
1467  if (Instruction *V =
1468  foldSelectICmpAndAnd(SI.getType(), ICI, TrueVal, FalseVal, Builder))
1469  return V;
1470 
1471  if (Instruction *V = foldSelectCtlzToCttz(ICI, TrueVal, FalseVal, Builder))
1472  return V;
1473 
1474  if (Value *V = foldSelectICmpAndOr(ICI, TrueVal, FalseVal, Builder))
1475  return replaceInstUsesWith(SI, V);
1476 
1477  if (Value *V = foldSelectICmpLshrAshr(ICI, TrueVal, FalseVal, Builder))
1478  return replaceInstUsesWith(SI, V);
1479 
1480  if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
1481  return replaceInstUsesWith(SI, V);
1482 
1483  if (Value *V = canonicalizeSaturatedSubtract(ICI, TrueVal, FalseVal, Builder))
1484  return replaceInstUsesWith(SI, V);
1485 
1486  if (Value *V = canonicalizeSaturatedAdd(ICI, TrueVal, FalseVal, Builder))
1487  return replaceInstUsesWith(SI, V);
1488 
1489  return Changed ? &SI : nullptr;
1490 }
1491 
1492 /// SI is a select whose condition is a PHI node (but the two may be in
1493 /// different blocks). See if the true/false values (V) are live in all of the
1494 /// predecessor blocks of the PHI. For example, cases like this can't be mapped:
1495 ///
1496 /// X = phi [ C1, BB1], [C2, BB2]
1497 /// Y = add
1498 /// Z = select X, Y, 0
1499 ///
1500 /// because Y is not live in BB1/BB2.
1501 static bool canSelectOperandBeMappingIntoPredBlock(const Value *V,
1502  const SelectInst &SI) {
1503  // If the value is a non-instruction value like a constant or argument, it
1504  // can always be mapped.
1505  const Instruction *I = dyn_cast<Instruction>(V);
1506  if (!I) return true;
1507 
1508  // If V is a PHI node defined in the same block as the condition PHI, we can
1509  // map the arguments.
1510  const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
1511 
1512  if (const PHINode *VP = dyn_cast<PHINode>(I))
1513  if (VP->getParent() == CondPHI->getParent())
1514  return true;
1515 
1516  // Otherwise, if the PHI and select are defined in the same block and if V is
1517  // defined in a different block, then we can transform it.
1518  if (SI.getParent() == CondPHI->getParent() &&
1519  I->getParent() != CondPHI->getParent())
1520  return true;
1521 
1522  // Otherwise we have a 'hard' case and we can't tell without doing more
1523  // detailed dominator based analysis, punt.
1524  return false;
1525 }
1526 
1527 /// We have an SPF (e.g. a min or max) of an SPF of the form:
1528 /// SPF2(SPF1(A, B), C)
1529 Instruction *InstCombiner::foldSPFofSPF(Instruction *Inner,
1530  SelectPatternFlavor SPF1,
1531  Value *A, Value *B,
1532  Instruction &Outer,
1533  SelectPatternFlavor SPF2, Value *C) {
1534  if (Outer.getType() != Inner->getType())
1535  return nullptr;
1536 
1537  if (C == A || C == B) {
1538  // MAX(MAX(A, B), B) -> MAX(A, B)
1539  // MIN(MIN(a, b), a) -> MIN(a, b)
1540  // TODO: This could be done in instsimplify.
1541  if (SPF1 == SPF2 && SelectPatternResult::isMinOrMax(SPF1))
1542  return replaceInstUsesWith(Outer, Inner);
1543 
1544  // MAX(MIN(a, b), a) -> a
1545  // MIN(MAX(a, b), a) -> a
1546  // TODO: This could be done in instsimplify.
1547  if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
1548  (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
1549  (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
1550  (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
1551  return replaceInstUsesWith(Outer, C);
1552  }
1553 
1554  if (SPF1 == SPF2) {
1555  const APInt *CB, *CC;
1556  if (match(B, m_APInt(CB)) && match(C, m_APInt(CC))) {
1557  // MIN(MIN(A, 23), 97) -> MIN(A, 23)
1558  // MAX(MAX(A, 97), 23) -> MAX(A, 97)
1559  // TODO: This could be done in instsimplify.
1560  if ((SPF1 == SPF_UMIN && CB->ule(*CC)) ||
1561  (SPF1 == SPF_SMIN && CB->sle(*CC)) ||
1562  (SPF1 == SPF_UMAX && CB->uge(*CC)) ||
1563  (SPF1 == SPF_SMAX && CB->sge(*CC)))
1564  return replaceInstUsesWith(Outer, Inner);
1565 
1566  // MIN(MIN(A, 97), 23) -> MIN(A, 23)
1567  // MAX(MAX(A, 23), 97) -> MAX(A, 97)
1568  if ((SPF1 == SPF_UMIN && CB->ugt(*CC)) ||
1569  (SPF1 == SPF_SMIN && CB->sgt(*CC)) ||
1570  (SPF1 == SPF_UMAX && CB->ult(*CC)) ||
1571  (SPF1 == SPF_SMAX && CB->slt(*CC))) {
1572  Outer.replaceUsesOfWith(Inner, A);
1573  return &Outer;
1574  }
1575  }
1576  }
1577 
1578  // max(max(A, B), min(A, B)) --> max(A, B)
1579  // min(min(A, B), max(A, B)) --> min(A, B)
1580  // TODO: This could be done in instsimplify.
1581  if (SPF1 == SPF2 &&
1582  ((SPF1 == SPF_UMIN && match(C, m_c_UMax(m_Specific(A), m_Specific(B)))) ||
1583  (SPF1 == SPF_SMIN && match(C, m_c_SMax(m_Specific(A), m_Specific(B)))) ||
1584  (SPF1 == SPF_UMAX && match(C, m_c_UMin(m_Specific(A), m_Specific(B)))) ||
1585  (SPF1 == SPF_SMAX && match(C, m_c_SMin(m_Specific(A), m_Specific(B))))))
1586  return replaceInstUsesWith(Outer, Inner);
1587 
1588  // ABS(ABS(X)) -> ABS(X)
1589  // NABS(NABS(X)) -> NABS(X)
1590  // TODO: This could be done in instsimplify.
1591  if (SPF1 == SPF2 && (SPF1 == SPF_ABS || SPF1 == SPF_NABS)) {
1592  return replaceInstUsesWith(Outer, Inner);
1593  }
1594 
1595  // ABS(NABS(X)) -> ABS(X)
1596  // NABS(ABS(X)) -> NABS(X)
1597  if ((SPF1 == SPF_ABS && SPF2 == SPF_NABS) ||
1598  (SPF1 == SPF_NABS && SPF2 == SPF_ABS)) {
1599  SelectInst *SI = cast<SelectInst>(Inner);
1600  Value *NewSI =
1601  Builder.CreateSelect(SI->getCondition(), SI->getFalseValue(),
1602  SI->getTrueValue(), SI->getName(), SI);
1603  return replaceInstUsesWith(Outer, NewSI);
1604  }
1605 
1606  auto IsFreeOrProfitableToInvert =
1607  [&](Value *V, Value *&NotV, bool &ElidesXor) {
1608  if (match(V, m_Not(m_Value(NotV)))) {
1609  // If V has at most 2 uses then we can get rid of the xor operation
1610  // entirely.
1611  ElidesXor |= !V->hasNUsesOrMore(3);
1612  return true;
1613  }
1614 
1615  if (isFreeToInvert(V, !V->hasNUsesOrMore(3))) {
1616  NotV = nullptr;
1617  return true;
1618  }
1619 
1620  return false;
1621  };
1622 
1623  Value *NotA, *NotB, *NotC;
1624  bool ElidesXor = false;
1625 
1626  // MIN(MIN(~A, ~B), ~C) == ~MAX(MAX(A, B), C)
1627  // MIN(MAX(~A, ~B), ~C) == ~MAX(MIN(A, B), C)
1628  // MAX(MIN(~A, ~B), ~C) == ~MIN(MAX(A, B), C)
1629  // MAX(MAX(~A, ~B), ~C) == ~MIN(MIN(A, B), C)
1630  //
1631  // This transform is performance neutral if we can elide at least one xor from
1632  // the set of three operands, since we'll be tacking on an xor at the very
1633  // end.
1634  if (SelectPatternResult::isMinOrMax(SPF1) &&
1636  IsFreeOrProfitableToInvert(A, NotA, ElidesXor) &&
1637  IsFreeOrProfitableToInvert(B, NotB, ElidesXor) &&
1638  IsFreeOrProfitableToInvert(C, NotC, ElidesXor) && ElidesXor) {
1639  if (!NotA)
1640  NotA = Builder.CreateNot(A);
1641  if (!NotB)
1642  NotB = Builder.CreateNot(B);
1643  if (!NotC)
1644  NotC = Builder.CreateNot(C);
1645 
1646  Value *NewInner = createMinMax(Builder, getInverseMinMaxFlavor(SPF1), NotA,
1647  NotB);
1648  Value *NewOuter = Builder.CreateNot(
1649  createMinMax(Builder, getInverseMinMaxFlavor(SPF2), NewInner, NotC));
1650  return replaceInstUsesWith(Outer, NewOuter);
1651  }
1652 
1653  return nullptr;
1654 }
1655 
1656 /// Turn select C, (X + Y), (X - Y) --> (X + (select C, Y, (-Y))).
1657 /// This is even legal for FP.
1658 static Instruction *foldAddSubSelect(SelectInst &SI,
1659  InstCombiner::BuilderTy &Builder) {
1660  Value *CondVal = SI.getCondition();
1661  Value *TrueVal = SI.getTrueValue();
1662  Value *FalseVal = SI.getFalseValue();
1663  auto *TI = dyn_cast<Instruction>(TrueVal);
1664  auto *FI = dyn_cast<Instruction>(FalseVal);
1665  if (!TI || !FI || !TI->hasOneUse() || !FI->hasOneUse())
1666  return nullptr;
1667 
1668  Instruction *AddOp = nullptr, *SubOp = nullptr;
1669  if ((TI->getOpcode() == Instruction::Sub &&
1670  FI->getOpcode() == Instruction::Add) ||
1671  (TI->getOpcode() == Instruction::FSub &&
1672  FI->getOpcode() == Instruction::FAdd)) {
1673  AddOp = FI;
1674  SubOp = TI;
1675  } else if ((FI->getOpcode() == Instruction::Sub &&
1676  TI->getOpcode() == Instruction::Add) ||
1677  (FI->getOpcode() == Instruction::FSub &&
1678  TI->getOpcode() == Instruction::FAdd)) {
1679  AddOp = TI;
1680  SubOp = FI;
1681  }
1682 
1683  if (AddOp) {
1684  Value *OtherAddOp = nullptr;
1685  if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
1686  OtherAddOp = AddOp->getOperand(1);
1687  } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
1688  OtherAddOp = AddOp->getOperand(0);
1689  }
1690 
1691  if (OtherAddOp) {
1692  // So at this point we know we have (Y -> OtherAddOp):
1693  // select C, (add X, Y), (sub X, Z)
1694  Value *NegVal; // Compute -Z
1695  if (SI.getType()->isFPOrFPVectorTy()) {
1696  NegVal = Builder.CreateFNeg(SubOp->getOperand(1));
1697  if (Instruction *NegInst = dyn_cast<Instruction>(NegVal)) {
1698  FastMathFlags Flags = AddOp->getFastMathFlags();
1699  Flags &= SubOp->getFastMathFlags();
1700  NegInst->setFastMathFlags(Flags);
1701  }
1702  } else {
1703  NegVal = Builder.CreateNeg(SubOp->getOperand(1));
1704  }
1705 
1706  Value *NewTrueOp = OtherAddOp;
1707  Value *NewFalseOp = NegVal;
1708  if (AddOp != TI)
1709  std::swap(NewTrueOp, NewFalseOp);
1710  Value *NewSel = Builder.CreateSelect(CondVal, NewTrueOp, NewFalseOp,
1711  SI.getName() + ".p", &SI);
1712 
1713  if (SI.getType()->isFPOrFPVectorTy()) {
1714  Instruction *RI =
1715  BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel);
1716 
1717  FastMathFlags Flags = AddOp->getFastMathFlags();
1718  Flags &= SubOp->getFastMathFlags();
1719  RI->setFastMathFlags(Flags);
1720  return RI;
1721  } else
1722  return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
1723  }
1724  }
1725  return nullptr;
1726 }
1727 
1728 Instruction *InstCombiner::foldSelectExtConst(SelectInst &Sel) {
1729  Constant *C;
1730  if (!match(Sel.getTrueValue(), m_Constant(C)) &&
1731  !match(Sel.getFalseValue(), m_Constant(C)))
1732  return nullptr;
1733 
1734  Instruction *ExtInst;
1735  if (!match(Sel.getTrueValue(), m_Instruction(ExtInst)) &&
1736  !match(Sel.getFalseValue(), m_Instruction(ExtInst)))
1737  return nullptr;
1738 
1739  auto ExtOpcode = ExtInst->getOpcode();
1740  if (ExtOpcode != Instruction::ZExt && ExtOpcode != Instruction::SExt)
1741  return nullptr;
1742 
1743  // If we are extending from a boolean type or if we can create a select that
1744  // has the same size operands as its condition, try to narrow the select.
1745  Value *X = ExtInst->getOperand(0);
1746  Type *SmallType = X->getType();
1747  Value *Cond = Sel.getCondition();
1748  auto *Cmp = dyn_cast<CmpInst>(Cond);
1749  if (!SmallType->isIntOrIntVectorTy(1) &&
1750  (!Cmp || Cmp->getOperand(0)->getType() != SmallType))
1751  return nullptr;
1752 
1753  // If the constant is the same after truncation to the smaller type and
1754  // extension to the original type, we can narrow the select.
1755  Type *SelType = Sel.getType();
1756  Constant *TruncC = ConstantExpr::getTrunc(C, SmallType);
1757  Constant *ExtC = ConstantExpr::getCast(ExtOpcode, TruncC, SelType);
1758  if (ExtC == C) {
1759  Value *TruncCVal = cast<Value>(TruncC);
1760  if (ExtInst == Sel.getFalseValue())
1761  std::swap(X, TruncCVal);
1762 
1763  // select Cond, (ext X), C --> ext(select Cond, X, C')
1764  // select Cond, C, (ext X) --> ext(select Cond, C', X)
1765  Value *NewSel = Builder.CreateSelect(Cond, X, TruncCVal, "narrow", &Sel);
1766  return CastInst::Create(Instruction::CastOps(ExtOpcode), NewSel, SelType);
1767  }
1768 
1769  // If one arm of the select is the extend of the condition, replace that arm
1770  // with the extension of the appropriate known bool value.
1771  if (Cond == X) {
1772  if (ExtInst == Sel.getTrueValue()) {
1773  // select X, (sext X), C --> select X, -1, C
1774  // select X, (zext X), C --> select X, 1, C
1775  Constant *One = ConstantInt::getTrue(SmallType);
1776  Constant *AllOnesOrOne = ConstantExpr::getCast(ExtOpcode, One, SelType);
1777  return SelectInst::Create(Cond, AllOnesOrOne, C, "", nullptr, &Sel);
1778  } else {
1779  // select X, C, (sext X) --> select X, C, 0
1780  // select X, C, (zext X) --> select X, C, 0
1781  Constant *Zero = ConstantInt::getNullValue(SelType);
1782  return SelectInst::Create(Cond, C, Zero, "", nullptr, &Sel);
1783  }
1784  }
1785 
1786  return nullptr;
1787 }
1788 
1789 /// Try to transform a vector select with a constant condition vector into a
1790 /// shuffle for easier combining with other shuffles and insert/extract.
1791 static Instruction *canonicalizeSelectToShuffle(SelectInst &SI) {
1792  Value *CondVal = SI.getCondition();
1793  Constant *CondC;
1794  if (!CondVal->getType()->isVectorTy() || !match(CondVal, m_Constant(CondC)))
1795  return nullptr;
1796 
1797  unsigned NumElts = CondVal->getType()->getVectorNumElements();
1799  Mask.reserve(NumElts);
1800  Type *Int32Ty = Type::getInt32Ty(CondVal->getContext());
1801  for (unsigned i = 0; i != NumElts; ++i) {
1802  Constant *Elt = CondC->getAggregateElement(i);
1803  if (!Elt)
1804  return nullptr;
1805 
1806  if (Elt->isOneValue()) {
1807  // If the select condition element is true, choose from the 1st vector.
1808  Mask.push_back(ConstantInt::get(Int32Ty, i));
1809  } else if (Elt->isNullValue()) {
1810  // If the select condition element is false, choose from the 2nd vector.
1811  Mask.push_back(ConstantInt::get(Int32Ty, i + NumElts));
1812  } else if (isa<UndefValue>(Elt)) {
1813  // Undef in a select condition (choose one of the operands) does not mean
1814  // the same thing as undef in a shuffle mask (any value is acceptable), so
1815  // give up.
1816  return nullptr;
1817  } else {
1818  // Bail out on a constant expression.
1819  return nullptr;
1820  }
1821  }
1822 
1823  return new ShuffleVectorInst(SI.getTrueValue(), SI.getFalseValue(),
1824  ConstantVector::get(Mask));
1825 }
1826 
1827 /// If we have a select of vectors with a scalar condition, try to convert that
1828 /// to a vector select by splatting the condition. A splat may get folded with
1829 /// other operations in IR and having all operands of a select be vector types
1830 /// is likely better for vector codegen.
1831 static Instruction *canonicalizeScalarSelectOfVecs(
1832  SelectInst &Sel, InstCombiner::BuilderTy &Builder) {
1833  Type *Ty = Sel.getType();
1834  if (!Ty->isVectorTy())
1835  return nullptr;
1836 
1837  // We can replace a single-use extract with constant index.
1838  Value *Cond = Sel.getCondition();
1840  return nullptr;
1841 
1842  // select (extelt V, Index), T, F --> select (splat V, Index), T, F
1843  // Splatting the extracted condition reduces code (we could directly create a
1844  // splat shuffle of the source vector to eliminate the intermediate step).
1845  unsigned NumElts = Ty->getVectorNumElements();
1846  Value *SplatCond = Builder.CreateVectorSplat(NumElts, Cond);
1847  Sel.setCondition(SplatCond);
1848  return &Sel;
1849 }
1850 
1851 /// Reuse bitcasted operands between a compare and select:
1852 /// select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
1853 /// bitcast (select (cmp (bitcast C), (bitcast D)), (bitcast C), (bitcast D))
1854 static Instruction *foldSelectCmpBitcasts(SelectInst &Sel,
1855  InstCombiner::BuilderTy &Builder) {
1856  Value *Cond = Sel.getCondition();
1857  Value *TVal = Sel.getTrueValue();
1858  Value *FVal = Sel.getFalseValue();
1859 
1860  CmpInst::Predicate Pred;
1861  Value *A, *B;
1862  if (!match(Cond, m_Cmp(Pred, m_Value(A), m_Value(B))))
1863  return nullptr;
1864 
1865  // The select condition is a compare instruction. If the select's true/false
1866  // values are already the same as the compare operands, there's nothing to do.
1867  if (TVal == A || TVal == B || FVal == A || FVal == B)
1868  return nullptr;
1869 
1870  Value *C, *D;
1871  if (!match(A, m_BitCast(m_Value(C))) || !match(B, m_BitCast(m_Value(D))))
1872  return nullptr;
1873 
1874  // select (cmp (bitcast C), (bitcast D)), (bitcast TSrc), (bitcast FSrc)
1875  Value *TSrc, *FSrc;
1876  if (!match(TVal, m_BitCast(m_Value(TSrc))) ||
1877  !match(FVal, m_BitCast(m_Value(FSrc))))
1878  return nullptr;
1879 
1880  // If the select true/false values are *different bitcasts* of the same source
1881  // operands, make the select operands the same as the compare operands and
1882  // cast the result. This is the canonical select form for min/max.
1883  Value *NewSel;
1884  if (TSrc == C && FSrc == D) {
1885  // select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
1886  // bitcast (select (cmp A, B), A, B)
1887  NewSel = Builder.CreateSelect(Cond, A, B, "", &Sel);
1888  } else if (TSrc == D && FSrc == C) {
1889  // select (cmp (bitcast C), (bitcast D)), (bitcast' D), (bitcast' C) -->
1890  // bitcast (select (cmp A, B), B, A)
1891  NewSel = Builder.CreateSelect(Cond, B, A, "", &Sel);
1892  } else {
1893  return nullptr;
1894  }
1895  return CastInst::CreateBitOrPointerCast(NewSel, Sel.getType());
1896 }
1897 
1898 /// Try to eliminate select instructions that test the returned flag of cmpxchg
1899 /// instructions.
1900 ///
1901 /// If a select instruction tests the returned flag of a cmpxchg instruction and
1902 /// selects between the returned value of the cmpxchg instruction its compare
1903 /// operand, the result of the select will always be equal to its false value.
1904 /// For example:
1905 ///
1906 /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst
1907 /// %1 = extractvalue { i64, i1 } %0, 1
1908 /// %2 = extractvalue { i64, i1 } %0, 0
1909 /// %3 = select i1 %1, i64 %compare, i64 %2
1910 /// ret i64 %3
1911 ///
1912 /// The returned value of the cmpxchg instruction (%2) is the original value
1913 /// located at %ptr prior to any update. If the cmpxchg operation succeeds, %2
1914 /// must have been equal to %compare. Thus, the result of the select is always
1915 /// equal to %2, and the code can be simplified to:
1916 ///
1917 /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst
1918 /// %1 = extractvalue { i64, i1 } %0, 0
1919 /// ret i64 %1
1920 ///
1921 static Instruction *foldSelectCmpXchg(SelectInst &SI) {
1922  // A helper that determines if V is an extractvalue instruction whose
1923  // aggregate operand is a cmpxchg instruction and whose single index is equal
1924  // to I. If such conditions are true, the helper returns the cmpxchg
1925  // instruction; otherwise, a nullptr is returned.
1926  auto isExtractFromCmpXchg = [](Value *V, unsigned I) -> AtomicCmpXchgInst * {
1927  auto *Extract = dyn_cast<ExtractValueInst>(V);
1928  if (!Extract)
1929  return nullptr;
1930  if (Extract->getIndices()[0] != I)
1931  return nullptr;
1932  return dyn_cast<AtomicCmpXchgInst>(Extract->getAggregateOperand());
1933  };
1934 
1935  // If the select has a single user, and this user is a select instruction that
1936  // we can simplify, skip the cmpxchg simplification for now.
1937  if (SI.hasOneUse())
1938  if (auto *Select = dyn_cast<SelectInst>(SI.user_back()))
1939  if (Select->getCondition() == SI.getCondition())
1940  if (Select->getFalseValue() == SI.getTrueValue() ||
1941  Select->getTrueValue() == SI.getFalseValue())
1942  return nullptr;
1943 
1944  // Ensure the select condition is the returned flag of a cmpxchg instruction.
1945  auto *CmpXchg = isExtractFromCmpXchg(SI.getCondition(), 1);
1946  if (!CmpXchg)
1947  return nullptr;
1948 
1949  // Check the true value case: The true value of the select is the returned
1950  // value of the same cmpxchg used by the condition, and the false value is the
1951  // cmpxchg instruction's compare operand.
1952  if (auto *X = isExtractFromCmpXchg(SI.getTrueValue(), 0))
1953  if (X == CmpXchg && X->getCompareOperand() == SI.getFalseValue()) {
1954  SI.setTrueValue(SI.getFalseValue());
1955  return &SI;
1956  }
1957 
1958  // Check the false value case: The false value of the select is the returned
1959  // value of the same cmpxchg used by the condition, and the true value is the
1960  // cmpxchg instruction's compare operand.
1961  if (auto *X = isExtractFromCmpXchg(SI.getFalseValue(), 0))
1962  if (X == CmpXchg && X->getCompareOperand() == SI.getTrueValue()) {
1963  SI.setTrueValue(SI.getFalseValue());
1964  return &SI;
1965  }
1966 
1967  return nullptr;
1968 }
1969 
1970 static Instruction *moveAddAfterMinMax(SelectPatternFlavor SPF, Value *X,
1971  Value *Y,
1972  InstCombiner::BuilderTy &Builder) {
1973  assert(SelectPatternResult::isMinOrMax(SPF) && "Expected min/max pattern");
1974  bool IsUnsigned = SPF == SelectPatternFlavor::SPF_UMIN ||
1976  // TODO: If InstSimplify could fold all cases where C2 <= C1, we could change
1977  // the constant value check to an assert.
1978  Value *A;
1979  const APInt *C1, *C2;
1980  if (IsUnsigned && match(X, m_NUWAdd(m_Value(A), m_APInt(C1))) &&
1981  match(Y, m_APInt(C2)) && C2->uge(*C1) && X->hasNUses(2)) {
1982  // umin (add nuw A, C1), C2 --> add nuw (umin A, C2 - C1), C1
1983  // umax (add nuw A, C1), C2 --> add nuw (umax A, C2 - C1), C1
1984  Value *NewMinMax = createMinMax(Builder, SPF, A,
1985  ConstantInt::get(X->getType(), *C2 - *C1));
1987  ConstantInt::get(X->getType(), *C1));
1988  }
1989 
1990  if (!IsUnsigned && match(X, m_NSWAdd(m_Value(A), m_APInt(C1))) &&
1991  match(Y, m_APInt(C2)) && X->hasNUses(2)) {
1992  bool Overflow;
1993  APInt Diff = C2->ssub_ov(*C1, Overflow);
1994  if (!Overflow) {
1995  // smin (add nsw A, C1), C2 --> add nsw (smin A, C2 - C1), C1
1996  // smax (add nsw A, C1), C2 --> add nsw (smax A, C2 - C1), C1
1997  Value *NewMinMax = createMinMax(Builder, SPF, A,
1998  ConstantInt::get(X->getType(), Diff));
2000  ConstantInt::get(X->getType(), *C1));
2001  }
2002  }
2003 
2004  return nullptr;
2005 }
2006 
2007 /// Reduce a sequence of min/max with a common operand.
2008 static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS,
2009  Value *RHS,
2010  InstCombiner::BuilderTy &Builder) {
2011  assert(SelectPatternResult::isMinOrMax(SPF) && "Expected a min/max");
2012  // TODO: Allow FP min/max with nnan/nsz.
2013  if (!LHS->getType()->isIntOrIntVectorTy())
2014  return nullptr;
2015 
2016  // Match 3 of the same min/max ops. Example: umin(umin(), umin()).
2017  Value *A, *B, *C, *D;
2018  SelectPatternResult L = matchSelectPattern(LHS, A, B);
2019  SelectPatternResult R = matchSelectPattern(RHS, C, D);
2020  if (SPF != L.Flavor || L.Flavor != R.Flavor)
2021  return nullptr;
2022 
2023  // Look for a common operand. The use checks are different than usual because
2024  // a min/max pattern typically has 2 uses of each op: 1 by the cmp and 1 by
2025  // the select.
2026  Value *MinMaxOp = nullptr;
2027  Value *ThirdOp = nullptr;
2028  if (!LHS->hasNUsesOrMore(3) && RHS->hasNUsesOrMore(3)) {
2029  // If the LHS is only used in this chain and the RHS is used outside of it,
2030  // reuse the RHS min/max because that will eliminate the LHS.
2031  if (D == A || C == A) {
2032  // min(min(a, b), min(c, a)) --> min(min(c, a), b)
2033  // min(min(a, b), min(a, d)) --> min(min(a, d), b)
2034  MinMaxOp = RHS;
2035  ThirdOp = B;
2036  } else if (D == B || C == B) {
2037  // min(min(a, b), min(c, b)) --> min(min(c, b), a)
2038  // min(min(a, b), min(b, d)) --> min(min(b, d), a)
2039  MinMaxOp = RHS;
2040  ThirdOp = A;
2041  }
2042  } else if (!RHS->hasNUsesOrMore(3)) {
2043  // Reuse the LHS. This will eliminate the RHS.
2044  if (D == A || D == B) {
2045  // min(min(a, b), min(c, a)) --> min(min(a, b), c)
2046  // min(min(a, b), min(c, b)) --> min(min(a, b), c)
2047  MinMaxOp = LHS;
2048  ThirdOp = C;
2049  } else if (C == A || C == B) {
2050  // min(min(a, b), min(b, d)) --> min(min(a, b), d)
2051  // min(min(a, b), min(c, b)) --> min(min(a, b), d)
2052  MinMaxOp = LHS;
2053  ThirdOp = D;
2054  }
2055  }
2056  if (!MinMaxOp || !ThirdOp)
2057  return nullptr;
2058 
2060  Value *CmpABC = Builder.CreateICmp(P, MinMaxOp, ThirdOp);
2061  return SelectInst::Create(CmpABC, MinMaxOp, ThirdOp);
2062 }
2063 
2064 /// Try to reduce a rotate pattern that includes a compare and select into a
2065 /// funnel shift intrinsic. Example:
2066 /// rotl32(a, b) --> (b == 0 ? a : ((a >> (32 - b)) | (a << b)))
2067 /// --> call llvm.fshl.i32(a, a, b)
2068 static Instruction *foldSelectRotate(SelectInst &Sel) {
2069  // The false value of the select must be a rotate of the true value.
2070  Value *Or0, *Or1;
2071  if (!match(Sel.getFalseValue(), m_OneUse(m_Or(m_Value(Or0), m_Value(Or1)))))
2072  return nullptr;
2073 
2074  Value *TVal = Sel.getTrueValue();
2075  Value *SA0, *SA1;
2076  if (!match(Or0, m_OneUse(m_LogicalShift(m_Specific(TVal), m_Value(SA0)))) ||
2077  !match(Or1, m_OneUse(m_LogicalShift(m_Specific(TVal), m_Value(SA1)))))
2078  return nullptr;
2079 
2080  auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode();
2081  auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode();
2082  if (ShiftOpcode0 == ShiftOpcode1)
2083  return nullptr;
2084 
2085  // We have one of these patterns so far:
2086  // select ?, TVal, (or (lshr TVal, SA0), (shl TVal, SA1))
2087  // select ?, TVal, (or (shl TVal, SA0), (lshr TVal, SA1))
2088  // This must be a power-of-2 rotate for a bitmasking transform to be valid.
2089  unsigned Width = Sel.getType()->getScalarSizeInBits();
2090  if (!isPowerOf2_32(Width))
2091  return nullptr;
2092 
2093  // Check the shift amounts to see if they are an opposite pair.
2094  Value *ShAmt;
2095  if (match(SA1, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(SA0)))))
2096  ShAmt = SA0;
2097  else if (match(SA0, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(SA1)))))
2098  ShAmt = SA1;
2099  else
2100  return nullptr;
2101 
2102  // Finally, see if the select is filtering out a shift-by-zero.
2103  Value *Cond = Sel.getCondition();
2104  ICmpInst::Predicate Pred;
2105  if (!match(Cond, m_OneUse(m_ICmp(Pred, m_Specific(ShAmt), m_ZeroInt()))) ||
2106  Pred != ICmpInst::ICMP_EQ)
2107  return nullptr;
2108 
2109  // This is a rotate that avoids shift-by-bitwidth UB in a suboptimal way.
2110  // Convert to funnel shift intrinsic.
2111  bool IsFshl = (ShAmt == SA0 && ShiftOpcode0 == BinaryOperator::Shl) ||
2112  (ShAmt == SA1 && ShiftOpcode1 == BinaryOperator::Shl);
2113  Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
2114  Function *F = Intrinsic::getDeclaration(Sel.getModule(), IID, Sel.getType());
2115  return IntrinsicInst::Create(F, { TVal, TVal, ShAmt });
2116 }
2117 
2119  Value *CondVal = SI.getCondition();
2120  Value *TrueVal = SI.getTrueValue();
2121  Value *FalseVal = SI.getFalseValue();
2122  Type *SelType = SI.getType();
2123 
2124  // FIXME: Remove this workaround when freeze related patches are done.
2125  // For select with undef operand which feeds into an equality comparison,
2126  // don't simplify it so loop unswitch can know the equality comparison
2127  // may have an undef operand. This is a workaround for PR31652 caused by
2128  // descrepancy about branch on undef between LoopUnswitch and GVN.
2129  if (isa<UndefValue>(TrueVal) || isa<UndefValue>(FalseVal)) {
2130  if (llvm::any_of(SI.users(), [&](User *U) {
2131  ICmpInst *CI = dyn_cast<ICmpInst>(U);
2132  if (CI && CI->isEquality())
2133  return true;
2134  return false;
2135  })) {
2136  return nullptr;
2137  }
2138  }
2139 
2140  if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal,
2141  SQ.getWithInstruction(&SI)))
2142  return replaceInstUsesWith(SI, V);
2143 
2144  if (Instruction *I = canonicalizeSelectToShuffle(SI))
2145  return I;
2146 
2147  if (Instruction *I = canonicalizeScalarSelectOfVecs(SI, Builder))
2148  return I;
2149 
2150  // Canonicalize a one-use integer compare with a non-canonical predicate by
2151  // inverting the predicate and swapping the select operands. This matches a
2152  // compare canonicalization for conditional branches.
2153  // TODO: Should we do the same for FP compares?
2154  CmpInst::Predicate Pred;
2155  if (match(CondVal, m_OneUse(m_ICmp(Pred, m_Value(), m_Value()))) &&
2156  !isCanonicalPredicate(Pred)) {
2157  // Swap true/false values and condition.
2158  CmpInst *Cond = cast<CmpInst>(CondVal);
2160  SI.setOperand(1, FalseVal);
2161  SI.setOperand(2, TrueVal);
2162  SI.swapProfMetadata();
2163  Worklist.Add(Cond);
2164  return &SI;
2165  }
2166 
2167  if (SelType->isIntOrIntVectorTy(1) &&
2168  TrueVal->getType() == CondVal->getType()) {
2169  if (match(TrueVal, m_One())) {
2170  // Change: A = select B, true, C --> A = or B, C
2171  return BinaryOperator::CreateOr(CondVal, FalseVal);
2172  }
2173  if (match(TrueVal, m_Zero())) {
2174  // Change: A = select B, false, C --> A = and !B, C
2175  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
2176  return BinaryOperator::CreateAnd(NotCond, FalseVal);
2177  }
2178  if (match(FalseVal, m_Zero())) {
2179  // Change: A = select B, C, false --> A = and B, C
2180  return BinaryOperator::CreateAnd(CondVal, TrueVal);
2181  }
2182  if (match(FalseVal, m_One())) {
2183  // Change: A = select B, C, true --> A = or !B, C
2184  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
2185  return BinaryOperator::CreateOr(NotCond, TrueVal);
2186  }
2187 
2188  // select a, a, b -> a | b
2189  // select a, b, a -> a & b
2190  if (CondVal == TrueVal)
2191  return BinaryOperator::CreateOr(CondVal, FalseVal);
2192  if (CondVal == FalseVal)
2193  return BinaryOperator::CreateAnd(CondVal, TrueVal);
2194 
2195  // select a, ~a, b -> (~a) & b
2196  // select a, b, ~a -> (~a) | b
2197  if (match(TrueVal, m_Not(m_Specific(CondVal))))
2198  return BinaryOperator::CreateAnd(TrueVal, FalseVal);
2199  if (match(FalseVal, m_Not(m_Specific(CondVal))))
2200  return BinaryOperator::CreateOr(TrueVal, FalseVal);
2201  }
2202 
2203  // Selecting between two integer or vector splat integer constants?
2204  //
2205  // Note that we don't handle a scalar select of vectors:
2206  // select i1 %c, <2 x i8> <1, 1>, <2 x i8> <0, 0>
2207  // because that may need 3 instructions to splat the condition value:
2208  // extend, insertelement, shufflevector.
2209  if (SelType->isIntOrIntVectorTy() &&
2210  CondVal->getType()->isVectorTy() == SelType->isVectorTy()) {
2211  // select C, 1, 0 -> zext C to int
2212  if (match(TrueVal, m_One()) && match(FalseVal, m_Zero()))
2213  return new ZExtInst(CondVal, SelType);
2214 
2215  // select C, -1, 0 -> sext C to int
2216  if (match(TrueVal, m_AllOnes()) && match(FalseVal, m_Zero()))
2217  return new SExtInst(CondVal, SelType);
2218 
2219  // select C, 0, 1 -> zext !C to int
2220  if (match(TrueVal, m_Zero()) && match(FalseVal, m_One())) {
2221  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
2222  return new ZExtInst(NotCond, SelType);
2223  }
2224 
2225  // select C, 0, -1 -> sext !C to int
2226  if (match(TrueVal, m_Zero()) && match(FalseVal, m_AllOnes())) {
2227  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
2228  return new SExtInst(NotCond, SelType);
2229  }
2230  }
2231 
2232  // See if we are selecting two values based on a comparison of the two values.
2233  if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
2234  if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
2235  // Canonicalize to use ordered comparisons by swapping the select
2236  // operands.
2237  //
2238  // e.g.
2239  // (X ugt Y) ? X : Y -> (X ole Y) ? Y : X
2240  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
2241  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
2242  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
2243  Builder.setFastMathFlags(FCI->getFastMathFlags());
2244  Value *NewCond = Builder.CreateFCmp(InvPred, TrueVal, FalseVal,
2245  FCI->getName() + ".inv");
2246 
2247  return SelectInst::Create(NewCond, FalseVal, TrueVal,
2248  SI.getName() + ".p");
2249  }
2250 
2251  // NOTE: if we wanted to, this is where to detect MIN/MAX
2252  } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
2253  // Canonicalize to use ordered comparisons by swapping the select
2254  // operands.
2255  //
2256  // e.g.
2257  // (X ugt Y) ? X : Y -> (X ole Y) ? X : Y
2258  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
2259  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
2260  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
2261  Builder.setFastMathFlags(FCI->getFastMathFlags());
2262  Value *NewCond = Builder.CreateFCmp(InvPred, FalseVal, TrueVal,
2263  FCI->getName() + ".inv");
2264 
2265  return SelectInst::Create(NewCond, FalseVal, TrueVal,
2266  SI.getName() + ".p");
2267  }
2268 
2269  // NOTE: if we wanted to, this is where to detect MIN/MAX
2270  }
2271  }
2272 
2273  // Canonicalize select with fcmp to fabs(). -0.0 makes this tricky. We need
2274  // fast-math-flags (nsz) or fsub with +0.0 (not fneg) for this to work. We
2275  // also require nnan because we do not want to unintentionally change the
2276  // sign of a NaN value.
2277  // FIXME: These folds should test/propagate FMF from the select, not the
2278  // fsub or fneg.
2279  // (X <= +/-0.0) ? (0.0 - X) : X --> fabs(X)
2280  Instruction *FSub;
2281  if (match(CondVal, m_FCmp(Pred, m_Specific(FalseVal), m_AnyZeroFP())) &&
2282  match(TrueVal, m_FSub(m_PosZeroFP(), m_Specific(FalseVal))) &&
2283  match(TrueVal, m_Instruction(FSub)) && FSub->hasNoNaNs() &&
2284  (Pred == FCmpInst::FCMP_OLE || Pred == FCmpInst::FCMP_ULE)) {
2285  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, FalseVal, FSub);
2286  return replaceInstUsesWith(SI, Fabs);
2287  }
2288  // (X > +/-0.0) ? X : (0.0 - X) --> fabs(X)
2289  if (match(CondVal, m_FCmp(Pred, m_Specific(TrueVal), m_AnyZeroFP())) &&
2290  match(FalseVal, m_FSub(m_PosZeroFP(), m_Specific(TrueVal))) &&
2291  match(FalseVal, m_Instruction(FSub)) && FSub->hasNoNaNs() &&
2292  (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_UGT)) {
2293  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, TrueVal, FSub);
2294  return replaceInstUsesWith(SI, Fabs);
2295  }
2296  // With nnan and nsz:
2297  // (X < +/-0.0) ? -X : X --> fabs(X)
2298  // (X <= +/-0.0) ? -X : X --> fabs(X)
2299  Instruction *FNeg;
2300  if (match(CondVal, m_FCmp(Pred, m_Specific(FalseVal), m_AnyZeroFP())) &&
2301  match(TrueVal, m_FNeg(m_Specific(FalseVal))) &&
2302  match(TrueVal, m_Instruction(FNeg)) &&
2303  FNeg->hasNoNaNs() && FNeg->hasNoSignedZeros() &&
2304  (Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_OLE ||
2305  Pred == FCmpInst::FCMP_ULT || Pred == FCmpInst::FCMP_ULE)) {
2306  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, FalseVal, FNeg);
2307  return replaceInstUsesWith(SI, Fabs);
2308  }
2309  // With nnan and nsz:
2310  // (X > +/-0.0) ? X : -X --> fabs(X)
2311  // (X >= +/-0.0) ? X : -X --> fabs(X)
2312  if (match(CondVal, m_FCmp(Pred, m_Specific(TrueVal), m_AnyZeroFP())) &&
2313  match(FalseVal, m_FNeg(m_Specific(TrueVal))) &&
2314  match(FalseVal, m_Instruction(FNeg)) &&
2315  FNeg->hasNoNaNs() && FNeg->hasNoSignedZeros() &&
2316  (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_OGE ||
2317  Pred == FCmpInst::FCMP_UGT || Pred == FCmpInst::FCMP_UGE)) {
2318  Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, TrueVal, FNeg);
2319  return replaceInstUsesWith(SI, Fabs);
2320  }
2321 
2322  // See if we are selecting two values based on a comparison of the two values.
2323  if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
2324  if (Instruction *Result = foldSelectInstWithICmp(SI, ICI))
2325  return Result;
2326 
2327  if (Instruction *Add = foldAddSubSelect(SI, Builder))
2328  return Add;
2329 
2330  // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
2331  auto *TI = dyn_cast<Instruction>(TrueVal);
2332  auto *FI = dyn_cast<Instruction>(FalseVal);
2333  if (TI && FI && TI->getOpcode() == FI->getOpcode())
2334  if (Instruction *IV = foldSelectOpOp(SI, TI, FI))
2335  return IV;
2336 
2337  if (Instruction *I = foldSelectExtConst(SI))
2338  return I;
2339 
2340  // See if we can fold the select into one of our operands.
2341  if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) {
2342  if (Instruction *FoldI = foldSelectIntoOp(SI, TrueVal, FalseVal))
2343  return FoldI;
2344 
2345  Value *LHS, *RHS;
2346  Instruction::CastOps CastOp;
2347  SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp);
2348  auto SPF = SPR.Flavor;
2349  if (SPF) {
2350  Value *LHS2, *RHS2;
2351  if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor)
2352  if (Instruction *R = foldSPFofSPF(cast<Instruction>(LHS), SPF2, LHS2,
2353  RHS2, SI, SPF, RHS))
2354  return R;
2355  if (SelectPatternFlavor SPF2 = matchSelectPattern(RHS, LHS2, RHS2).Flavor)
2356  if (Instruction *R = foldSPFofSPF(cast<Instruction>(RHS), SPF2, LHS2,
2357  RHS2, SI, SPF, LHS))
2358  return R;
2359  // TODO.
2360  // ABS(-X) -> ABS(X)
2361  }
2362 
2364  // Canonicalize so that
2365  // - type casts are outside select patterns.
2366  // - float clamp is transformed to min/max pattern
2367 
2368  bool IsCastNeeded = LHS->getType() != SelType;
2369  Value *CmpLHS = cast<CmpInst>(CondVal)->getOperand(0);
2370  Value *CmpRHS = cast<CmpInst>(CondVal)->getOperand(1);
2371  if (IsCastNeeded ||
2372  (LHS->getType()->isFPOrFPVectorTy() &&
2373  ((CmpLHS != LHS && CmpLHS != RHS) ||
2374  (CmpRHS != LHS && CmpRHS != RHS)))) {
2375  CmpInst::Predicate MinMaxPred = getMinMaxPred(SPF, SPR.Ordered);
2376 
2377  Value *Cmp;
2378  if (CmpInst::isIntPredicate(MinMaxPred)) {
2379  Cmp = Builder.CreateICmp(MinMaxPred, LHS, RHS);
2380  } else {
2381  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
2382  auto FMF =
2383  cast<FPMathOperator>(SI.getCondition())->getFastMathFlags();
2384  Builder.setFastMathFlags(FMF);
2385  Cmp = Builder.CreateFCmp(MinMaxPred, LHS, RHS);
2386  }
2387 
2388  Value *NewSI = Builder.CreateSelect(Cmp, LHS, RHS, SI.getName(), &SI);
2389  if (!IsCastNeeded)
2390  return replaceInstUsesWith(SI, NewSI);
2391 
2392  Value *NewCast = Builder.CreateCast(CastOp, NewSI, SelType);
2393  return replaceInstUsesWith(SI, NewCast);
2394  }
2395 
2396  // MAX(~a, ~b) -> ~MIN(a, b)
2397  // MAX(~a, C) -> ~MIN(a, ~C)
2398  // MIN(~a, ~b) -> ~MAX(a, b)
2399  // MIN(~a, C) -> ~MAX(a, ~C)
2400  auto moveNotAfterMinMax = [&](Value *X, Value *Y) -> Instruction * {
2401  Value *A;
2402  if (match(X, m_Not(m_Value(A))) && !X->hasNUsesOrMore(3) &&
2403  !isFreeToInvert(A, A->hasOneUse()) &&
2404  // Passing false to only consider m_Not and constants.
2405  isFreeToInvert(Y, false)) {
2406  Value *B = Builder.CreateNot(Y);
2407  Value *NewMinMax = createMinMax(Builder, getInverseMinMaxFlavor(SPF),
2408  A, B);
2409  // Copy the profile metadata.
2410  if (MDNode *MD = SI.getMetadata(LLVMContext::MD_prof)) {
2411  cast<SelectInst>(NewMinMax)->setMetadata(LLVMContext::MD_prof, MD);
2412  // Swap the metadata if the operands are swapped.
2413  if (X == SI.getFalseValue() && Y == SI.getTrueValue())
2414  cast<SelectInst>(NewMinMax)->swapProfMetadata();
2415  }
2416 
2417  return BinaryOperator::CreateNot(NewMinMax);
2418  }
2419 
2420  return nullptr;
2421  };
2422 
2423  if (Instruction *I = moveNotAfterMinMax(LHS, RHS))
2424  return I;
2425  if (Instruction *I = moveNotAfterMinMax(RHS, LHS))
2426  return I;
2427 
2428  if (Instruction *I = moveAddAfterMinMax(SPF, LHS, RHS, Builder))
2429  return I;
2430 
2431  if (Instruction *I = factorizeMinMaxTree(SPF, LHS, RHS, Builder))
2432  return I;
2433  }
2434  }
2435 
2436  // Canonicalize select of FP values where NaN and -0.0 are not valid as
2437  // minnum/maxnum intrinsics.
2438  if (isa<FPMathOperator>(SI) && SI.hasNoNaNs() && SI.hasNoSignedZeros()) {
2439  Value *X, *Y;
2440  if (match(&SI, m_OrdFMax(m_Value(X), m_Value(Y))))
2441  return replaceInstUsesWith(
2442  SI, Builder.CreateBinaryIntrinsic(Intrinsic::maxnum, X, Y, &SI));
2443 
2444  if (match(&SI, m_OrdFMin(m_Value(X), m_Value(Y))))
2445  return replaceInstUsesWith(
2446  SI, Builder.CreateBinaryIntrinsic(Intrinsic::minnum, X, Y, &SI));
2447  }
2448 
2449  // See if we can fold the select into a phi node if the condition is a select.
2450  if (auto *PN = dyn_cast<PHINode>(SI.getCondition()))
2451  // The true/false values have to be live in the PHI predecessor's blocks.
2452  if (canSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
2453  canSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
2454  if (Instruction *NV = foldOpIntoPhi(SI, PN))
2455  return NV;
2456 
2457  if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
2458  if (TrueSI->getCondition()->getType() == CondVal->getType()) {
2459  // select(C, select(C, a, b), c) -> select(C, a, c)
2460  if (TrueSI->getCondition() == CondVal) {
2461  if (SI.getTrueValue() == TrueSI->getTrueValue())
2462  return nullptr;
2463  SI.setOperand(1, TrueSI->getTrueValue());
2464  return &SI;
2465  }
2466  // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
2467  // We choose this as normal form to enable folding on the And and shortening
2468  // paths for the values (this helps GetUnderlyingObjects() for example).
2469  if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
2470  Value *And = Builder.CreateAnd(CondVal, TrueSI->getCondition());
2471  SI.setOperand(0, And);
2472  SI.setOperand(1, TrueSI->getTrueValue());
2473  return &SI;
2474  }
2475  }
2476  }
2477  if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
2478  if (FalseSI->getCondition()->getType() == CondVal->getType()) {
2479  // select(C, a, select(C, b, c)) -> select(C, a, c)
2480  if (FalseSI->getCondition() == CondVal) {
2481  if (SI.getFalseValue() == FalseSI->getFalseValue())
2482  return nullptr;
2483  SI.setOperand(2, FalseSI->getFalseValue());
2484  return &SI;
2485  }
2486  // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
2487  if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
2488  Value *Or = Builder.CreateOr(CondVal, FalseSI->getCondition());
2489  SI.setOperand(0, Or);
2490  SI.setOperand(2, FalseSI->getFalseValue());
2491  return &SI;
2492  }
2493  }
2494  }
2495 
2496  auto canMergeSelectThroughBinop = [](BinaryOperator *BO) {
2497  // The select might be preventing a division by 0.
2498  switch (BO->getOpcode()) {
2499  default:
2500  return true;
2501  case Instruction::SRem:
2502  case Instruction::URem:
2503  case Instruction::SDiv:
2504  case Instruction::UDiv:
2505  return false;
2506  }
2507  };
2508 
2509  // Try to simplify a binop sandwiched between 2 selects with the same
2510  // condition.
2511  // select(C, binop(select(C, X, Y), W), Z) -> select(C, binop(X, W), Z)
2512  BinaryOperator *TrueBO;
2513  if (match(TrueVal, m_OneUse(m_BinOp(TrueBO))) &&
2514  canMergeSelectThroughBinop(TrueBO)) {
2515  if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(0))) {
2516  if (TrueBOSI->getCondition() == CondVal) {
2517  TrueBO->setOperand(0, TrueBOSI->getTrueValue());
2518  Worklist.Add(TrueBO);
2519  return &SI;
2520  }
2521  }
2522  if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(1))) {
2523  if (TrueBOSI->getCondition() == CondVal) {
2524  TrueBO->setOperand(1, TrueBOSI->getTrueValue());
2525  Worklist.Add(TrueBO);
2526  return &SI;
2527  }
2528  }
2529  }
2530 
2531  // select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W))
2532  BinaryOperator *FalseBO;
2533  if (match(FalseVal, m_OneUse(m_BinOp(FalseBO))) &&
2534  canMergeSelectThroughBinop(FalseBO)) {
2535  if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(0))) {
2536  if (FalseBOSI->getCondition() == CondVal) {
2537  FalseBO->setOperand(0, FalseBOSI->getFalseValue());
2538  Worklist.Add(FalseBO);
2539  return &SI;
2540  }
2541  }
2542  if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(1))) {
2543  if (FalseBOSI->getCondition() == CondVal) {
2544  FalseBO->setOperand(1, FalseBOSI->getFalseValue());
2545  Worklist.Add(FalseBO);
2546  return &SI;
2547  }
2548  }
2549  }
2550 
2551  Value *NotCond;
2552  if (match(CondVal, m_Not(m_Value(NotCond)))) {
2553  SI.setOperand(0, NotCond);
2554  SI.setOperand(1, FalseVal);
2555  SI.setOperand(2, TrueVal);
2556  SI.swapProfMetadata();
2557  return &SI;
2558  }
2559 
2560  if (VectorType *VecTy = dyn_cast<VectorType>(SelType)) {
2561  unsigned VWidth = VecTy->getNumElements();
2562  APInt UndefElts(VWidth, 0);
2563  APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
2564  if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) {
2565  if (V != &SI)
2566  return replaceInstUsesWith(SI, V);
2567  return &SI;
2568  }
2569  }
2570 
2571  // If we can compute the condition, there's no need for a select.
2572  // Like the above fold, we are attempting to reduce compile-time cost by
2573  // putting this fold here with limitations rather than in InstSimplify.
2574  // The motivation for this call into value tracking is to take advantage of
2575  // the assumption cache, so make sure that is populated.
2576  if (!CondVal->getType()->isVectorTy() && !AC.assumptions().empty()) {
2577  KnownBits Known(1);
2578  computeKnownBits(CondVal, Known, 0, &SI);
2579  if (Known.One.isOneValue())
2580  return replaceInstUsesWith(SI, TrueVal);
2581  if (Known.Zero.isOneValue())
2582  return replaceInstUsesWith(SI, FalseVal);
2583  }
2584 
2585  if (Instruction *BitCastSel = foldSelectCmpBitcasts(SI, Builder))
2586  return BitCastSel;
2587 
2588  // Simplify selects that test the returned flag of cmpxchg instructions.
2589  if (Instruction *Select = foldSelectCmpXchg(SI))
2590  return Select;
2591 
2592  if (Instruction *Select = foldSelectBinOpIdentity(SI, TLI))
2593  return Select;
2594 
2595  if (Instruction *Rot = foldSelectRotate(SI))
2596  return Rot;
2597 
2598  return nullptr;
2599 }
MaxMin_match< ICmpInst, LHS, RHS, umin_pred_ty > m_UMin(const LHS &L, const RHS &R)
cst_pred_ty< icmp_pred_with_threshold > m_SpecificInt_ICMP(ICmpInst::Predicate Predicate, const APInt &Threshold)
Match an integer or vector with every element comparing &#39;pred&#39; (eg/ne/...) to Threshold.
Definition: PatternMatch.h:494
bool isFPPredicate() const
Definition: InstrTypes.h:824
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:874
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:616
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:2210
This class is the base class for the comparison instructions.
Definition: InstrTypes.h:722
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...
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...
ThreeOps_match< Cond, LHS, RHS, Instruction::Select > m_Select(const Cond &C, const LHS &L, const RHS &R)
Matches SelectInst.
static APInt getAllOnesValue(unsigned numBits)
Get the all-ones value.
Definition: APInt.h:561
BinaryOp_match< LHS, RHS, Instruction::Sub > m_Sub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:771
is_zero m_Zero()
Match any null constant or a vector with all elements equal to 0.
Definition: PatternMatch.h:403
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:2383
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:1886
This class represents lattice values for constants.
Definition: AllocatorList.h:23
BinaryOps getOpcode() const
Definition: InstrTypes.h:402
Value * CreateXor(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1320
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:538
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:909
Value * CreateICmpSLT(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2132
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:758
unsigned less than
Definition: InstrTypes.h:757
BinaryOp_match< LHS, RHS, Instruction::AShr > m_AShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:904
0 1 0 0 True if ordered and less than
Definition: InstrTypes.h:738
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:743
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:748
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:1246
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:777
static Constant * getSub(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2261
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:230
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.
static bool isFreeToInvert(Value *V, bool WillInvertAllUses)
Return true if the specified value is free to invert (apply ~ to).
cst_pred_ty< is_zero_int > m_ZeroInt()
Match an integer 0 or a vector with all elements equal to 0.
Definition: PatternMatch.h:391
bool Ordered
Only applicable if Flavor is SPF_FMINNUM or SPF_FMAXNUM.
static APInt getSignedMaxValue(unsigned numBits)
Gets maximum signed value of APInt for a specific bit width.
Definition: APInt.h:534
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1517
Signed maximum.
BinOpPred_match< LHS, RHS, is_logical_shift_op > m_LogicalShift(const LHS &L, const RHS &R)
Matches logical shift operations.
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:289
Value * CreateNot(Value *V, const Twine &Name="")
Definition: IRBuilder.h:1522
Value * getArgOperand(unsigned i) const
Definition: InstrTypes.h:1241
static BinaryOperator * CreateNSW(BinaryOps Opc, Value *V1, Value *V2, const Twine &Name="")
Definition: InstrTypes.h:289
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:47
CmpClass_match< LHS, RHS, FCmpInst, FCmpInst::Predicate > m_FCmp(FCmpInst::Predicate &Pred, const LHS &L, const RHS &R)
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:886
TwoOps_match< Val_t, Idx_t, Instruction::ExtractElement > m_ExtractElement(const Val_t &Val, const Idx_t &Idx)
Matches ExtractElementInst.
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:831
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
static Value * foldSelectICmpLshrAshr(const ICmpInst *IC, Value *TrueVal, Value *FalseVal, InstCombiner::BuilderTy &Builder)
We want to turn: (select (icmp sgt x, C), lshr (X, Y), ashr (X, Y)); iff C s>= -1 (select (icmp slt x...
bool isUnsigned() const
Definition: InstrTypes.h:908
CastClass_match< OpTy, Instruction::Trunc > m_Trunc(const OpTy &Op)
Matches Trunc.
static Constant * AddOne(Constant *C)
Add one to a Constant.
0 1 0 1 True if ordered and less than or equal
Definition: InstrTypes.h:739
static Constant * getSExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1682
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:759
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1696
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:970
bool isNullValue() const
Return true if this is the value that would be returned by getNullValue.
Definition: Constants.cpp:85
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:246
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< FCmpInst, LHS, RHS, ofmin_pred_ty > m_OrdFMin(const LHS &L, const RHS &R)
Match an &#39;ordered&#39; floating point minimum function.
MaxMin_match< ICmpInst, LHS, RHS, smin_pred_ty > m_SMin(const LHS &L, const RHS &R)
MDNode * getMetadata(unsigned KindID) const
Get the metadata of given kind attached to this Instruction.
Definition: Instruction.h:244
Value * CreateVectorSplat(unsigned NumElts, Value *V, const Twine &Name="")
Return a vector value that contains.
Definition: IRBuilder.h:2463
class_match< ConstantInt > m_ConstantInt()
Match an arbitrary ConstantInt and ignore it.
Definition: PatternMatch.h:81
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:524
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:203
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:412
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:1093
static BinaryOperator * CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
void SetInsertPoint(BasicBlock *TheBB)
This specifies that created instructions should be appended to the end of the specified block...
Definition: IRBuilder.h:132
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:1294
Constant * getAggregateElement(unsigned Elt) const
For aggregates (struct/array/vector) return the constant that corresponds to the specified element if...
Definition: Constants.cpp:359
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:307
MaxMin_match< ICmpInst, LHS, RHS, umin_pred_ty, true > m_c_UMin(const LHS &L, const RHS &R)
Matches a UMin with LHS and RHS in either order.
Value * CreateFCmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:2218
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:898
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:194
Value * CreateAShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1248
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:465
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
BinaryOp_match< LHS, RHS, Instruction::Or > m_Or(const LHS &L, const RHS &R)
Definition: PatternMatch.h:880
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:2286
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:308
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:1944
specific_intval m_SpecificInt(APInt V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:664
cst_pred_ty< is_all_ones > m_AllOnes()
Match an integer or vector with all bits set.
Definition: PatternMatch.h:336
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:587
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:1172
Value * CreateNeg(Value *V, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1485
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:732
static Constant * getBinOpIdentity(unsigned Opcode, Type *Ty, bool AllowRHSConstant=false)
Return the identity constant for a binary opcode.
Definition: Constants.cpp:2338
Value * CreateICmpSGE(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2128
MaxMin_match< ICmpInst, LHS, RHS, smax_pred_ty, true > m_c_SMax(const LHS &L, const RHS &R)
Matches an SMax with LHS and RHS in either order.
CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF, bool Ordered=false)
Return the canonical comparison predicate for the specified minimum/maximum flavor.
static Constant * getICmp(unsigned short pred, Constant *LHS, Constant *RHS, bool OnlyIfReduced=false)
get* - Return some common constants without having to specify the full Instruction::OPCODE identifier...
Definition: Constants.cpp:2065
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:40
const Value * getCondition() const
bool isCast() const
Definition: Instruction.h:133
C setMetadata(LLVMContext::MD_range, MDNode::get(Context, LowAndHigh))
1 1 0 1 True if unordered, less than, or equal
Definition: InstrTypes.h:747
void swapProfMetadata()
If the instruction has "branch_weights" MD_prof metadata and the MDNode has three operands (including...
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
LLVM_READONLY APFloat maxnum(const APFloat &A, const APFloat &B)
Implements IEEE maxNum semantics.
Definition: APFloat.h:1253
deferredval_ty< Value > m_Deferred(Value *const &V)
A commutative-friendly version of m_Specific().
Definition: PatternMatch.h:600
signed greater than
Definition: InstrTypes.h:759
CastClass_match< OpTy, Instruction::SExt > m_SExt(const OpTy &Op)
Matches SExt.
Floating point maxnum.
MaxMin_match< ICmpInst, LHS, RHS, umax_pred_ty, true > m_c_UMax(const LHS &L, const RHS &R)
Matches a UMax with LHS and RHS in either order.
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:736
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:134
1 1 0 0 True if unordered or less than
Definition: InstrTypes.h:746
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
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:761
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:1668
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:653
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1292
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:609
bool isCommutative() const
Return true if the instruction is commutative:
Definition: Instruction.h:498
Instruction * visitSelectInst(SelectInst &SI)
void setPredicate(Predicate P)
Set the predicate for this instruction to the specified value.
Definition: InstrTypes.h:812
OverflowingBinaryOp_match< LHS, RHS, Instruction::Add, OverflowingBinaryOperator::NoSignedWrap > m_NSWAdd(const LHS &L, const RHS &R)
Definition: PatternMatch.h:937
void setOperand(unsigned i, Value *Val)
Definition: User.h:174
unsigned logBase2() const
Definition: APInt.h:1756
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:566
bool isIntPredicate() const
Definition: InstrTypes.h:825
Class to represent vector types.
Definition: DerivedTypes.h:432
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:420
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1561
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1207
const Value * getFalseValue() const
void setCondition(Value *V)
static BinaryOperator * CreateFNegFMF(Value *Op, Instruction *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:283
static APInt getSelectFoldableConstant(BinaryOperator *I)
For the same transformation as the previous function, return the identity constant that goes into the...
static Constant * getNeg(Constant *C, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2231
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:807
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:814
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:180
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:756
static bool isUnordered(Predicate predicate)
Determine if the predicate is an unordered operation.
MaxMin_match< ICmpInst, LHS, RHS, smin_pred_ty, true > m_c_SMin(const LHS &L, const RHS &R)
Matches an SMin with LHS and RHS in either order.
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
bool isEquality() const
Return true if this predicate is either EQ or NE.
#define I(x, y, z)
Definition: MD5.cpp:58
llvm::Optional< std::pair< CmpInst::Predicate, Constant * > > getFlippedStrictnessPredicateAndConstant(CmpInst::Predicate Pred, Constant *C)
MaxMin_match< ICmpInst, LHS, RHS, smax_pred_ty > m_SMax(const LHS &L, const RHS &R)
void swapValues()
Swap the true and false values of the select instruction.
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)
1 0 1 0 True if unordered or greater than
Definition: InstrTypes.h:744
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:1268
InstTy * Insert(InstTy *I, const Twine &Name="") const
Insert and return the specified instruction.
Definition: IRBuilder.h:830
bool isFPOrFPVectorTy() const
Return true if this is a FP type or a vector of FP.
Definition: Type.h:185
bool isOneValue() const
Returns true if the value is one.
Definition: Constants.cpp:126
Value * CreateCast(Instruction::CastOps Op, Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1999
Value * SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for a BinaryOperator, fold the result or return null.
static GetElementPtrInst * CreateInBounds(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Create an "inbounds" getelementptr.
Definition: Instructions.h:943
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
MaxMin_match< FCmpInst, LHS, RHS, ofmax_pred_ty > m_OrdFMax(const LHS &L, const RHS &R)
Match an &#39;ordered&#39; floating point maximum function.
0 0 0 1 True if ordered and equal
Definition: InstrTypes.h:735
LLVM Value Representation.
Definition: Value.h:74
This file provides internal interfaces used to implement the InstCombine.
1 0 1 1 True if unordered, greater than, or equal
Definition: InstrTypes.h:745
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:382
#define LLVM_FALLTHROUGH
LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
Definition: Compiler.h:273
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:225
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:1228
match_combine_and< LTy, RTy > m_CombineAnd(const LTy &L, const RTy &R)
Combine two pattern matchers matching L && R.
Definition: PatternMatch.h:148
cst_pred_ty< is_any_apint > m_AnyIntegralConstant()
Match an integer or vector with any integral constant.
Definition: PatternMatch.h:327
bool hasNoNaNs() const
Determine whether the no-NaNs flag is set.
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:433
Convenience struct for specifying and reasoning about fast-math flags.
Definition: Operator.h:159
unsigned greater than
Definition: InstrTypes.h:755
Predicate getSwappedPredicate() const
For example, EQ->EQ, SLE->SGE, ULT->UGT, OEQ->OEQ, ULE->UGE, OLT->OGT, etc.
Definition: InstrTypes.h:847
static APInt getNullValue(unsigned numBits)
Get the &#39;0&#39; value.
Definition: APInt.h:568
cstfp_pred_ty< is_any_zero_fp > m_AnyZeroFP()
Match a floating-point negative zero or positive zero.
Definition: PatternMatch.h:515
0 0 1 1 True if ordered and greater than or equal
Definition: InstrTypes.h:737
static Constant * get(ArrayRef< Constant *> V)
Definition: Constants.cpp:1110
Value * CreateFNeg(Value *V, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1503
LLVM_READONLY APFloat minnum(const APFloat &A, const APFloat &B)
Implements IEEE minNum semantics.
Definition: APFloat.h:1242
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:558
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
signed greater or equal
Definition: InstrTypes.h:760
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)