LLVM  7.0.0svn
InstCombineSelect.cpp
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1 //===- InstCombineSelect.cpp ----------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the visitSelect function.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "InstCombineInternal.h"
15 #include "llvm/ADT/APInt.h"
16 #include "llvm/ADT/Optional.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/IR/BasicBlock.h"
24 #include "llvm/IR/Constant.h"
25 #include "llvm/IR/Constants.h"
26 #include "llvm/IR/DerivedTypes.h"
27 #include "llvm/IR/IRBuilder.h"
28 #include "llvm/IR/InstrTypes.h"
29 #include "llvm/IR/Instruction.h"
30 #include "llvm/IR/Instructions.h"
31 #include "llvm/IR/IntrinsicInst.h"
32 #include "llvm/IR/Intrinsics.h"
33 #include "llvm/IR/Operator.h"
34 #include "llvm/IR/PatternMatch.h"
35 #include "llvm/IR/Type.h"
36 #include "llvm/IR/User.h"
37 #include "llvm/IR/Value.h"
38 #include "llvm/Support/Casting.h"
40 #include "llvm/Support/KnownBits.h"
42 #include <cassert>
43 #include <utility>
44 
45 using namespace llvm;
46 using namespace PatternMatch;
47 
48 #define DEBUG_TYPE "instcombine"
49 
51  SelectPatternFlavor SPF, Value *A, Value *B) {
53  assert(CmpInst::isIntPredicate(Pred) && "Expected integer predicate");
54  return Builder.CreateSelect(Builder.CreateICmp(Pred, A, B), A, B);
55 }
56 
57 /// This folds:
58 /// select (icmp eq (and X, C1)), TC, FC
59 /// iff C1 is a power 2 and the difference between TC and FC is a power-of-2.
60 /// To something like:
61 /// (shr (and (X, C1)), (log2(C1) - log2(TC-FC))) + FC
62 /// Or:
63 /// (shl (and (X, C1)), (log2(TC-FC) - log2(C1))) + FC
64 /// With some variations depending if FC is larger than TC, or the shift
65 /// isn't needed, or the bit widths don't match.
67  InstCombiner::BuilderTy &Builder) {
68  const APInt *SelTC, *SelFC;
69  if (!match(Sel.getTrueValue(), m_APInt(SelTC)) ||
70  !match(Sel.getFalseValue(), m_APInt(SelFC)))
71  return nullptr;
72 
73  // If this is a vector select, we need a vector compare.
74  Type *SelType = Sel.getType();
75  if (SelType->isVectorTy() != Cmp->getType()->isVectorTy())
76  return nullptr;
77 
78  Value *V;
79  APInt AndMask;
80  bool CreateAnd = false;
81  ICmpInst::Predicate Pred = Cmp->getPredicate();
82  if (ICmpInst::isEquality(Pred)) {
83  if (!match(Cmp->getOperand(1), m_Zero()))
84  return nullptr;
85 
86  V = Cmp->getOperand(0);
87  const APInt *AndRHS;
88  if (!match(V, m_And(m_Value(), m_Power2(AndRHS))))
89  return nullptr;
90 
91  AndMask = *AndRHS;
92  } else if (decomposeBitTestICmp(Cmp->getOperand(0), Cmp->getOperand(1),
93  Pred, V, AndMask)) {
94  assert(ICmpInst::isEquality(Pred) && "Not equality test?");
95  if (!AndMask.isPowerOf2())
96  return nullptr;
97 
98  CreateAnd = true;
99  } else {
100  return nullptr;
101  }
102 
103  // In general, when both constants are non-zero, we would need an offset to
104  // replace the select. This would require more instructions than we started
105  // with. But there's one special-case that we handle here because it can
106  // simplify/reduce the instructions.
107  APInt TC = *SelTC;
108  APInt FC = *SelFC;
109  if (!TC.isNullValue() && !FC.isNullValue()) {
110  // If the select constants differ by exactly one bit and that's the same
111  // bit that is masked and checked by the select condition, the select can
112  // be replaced by bitwise logic to set/clear one bit of the constant result.
113  if (TC.getBitWidth() != AndMask.getBitWidth() || (TC ^ FC) != AndMask)
114  return nullptr;
115  if (CreateAnd) {
116  // If we have to create an 'and', then we must kill the cmp to not
117  // increase the instruction count.
118  if (!Cmp->hasOneUse())
119  return nullptr;
120  V = Builder.CreateAnd(V, ConstantInt::get(SelType, AndMask));
121  }
122  bool ExtraBitInTC = TC.ugt(FC);
123  if (Pred == ICmpInst::ICMP_EQ) {
124  // If the masked bit in V is clear, clear or set the bit in the result:
125  // (V & AndMaskC) == 0 ? TC : FC --> (V & AndMaskC) ^ TC
126  // (V & AndMaskC) == 0 ? TC : FC --> (V & AndMaskC) | TC
127  Constant *C = ConstantInt::get(SelType, TC);
128  return ExtraBitInTC ? Builder.CreateXor(V, C) : Builder.CreateOr(V, C);
129  }
130  if (Pred == ICmpInst::ICMP_NE) {
131  // If the masked bit in V is set, set or clear the bit in the result:
132  // (V & AndMaskC) != 0 ? TC : FC --> (V & AndMaskC) | FC
133  // (V & AndMaskC) != 0 ? TC : FC --> (V & AndMaskC) ^ FC
134  Constant *C = ConstantInt::get(SelType, FC);
135  return ExtraBitInTC ? Builder.CreateOr(V, C) : Builder.CreateXor(V, C);
136  }
137  llvm_unreachable("Only expecting equality predicates");
138  }
139 
140  // Make sure one of the select arms is a power-of-2.
141  if (!TC.isPowerOf2() && !FC.isPowerOf2())
142  return nullptr;
143 
144  // Determine which shift is needed to transform result of the 'and' into the
145  // desired result.
146  const APInt &ValC = !TC.isNullValue() ? TC : FC;
147  unsigned ValZeros = ValC.logBase2();
148  unsigned AndZeros = AndMask.logBase2();
149 
150  // Insert the 'and' instruction on the input to the truncate.
151  if (CreateAnd)
152  V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), AndMask));
153 
154  // If types don't match, we can still convert the select by introducing a zext
155  // or a trunc of the 'and'.
156  if (ValZeros > AndZeros) {
157  V = Builder.CreateZExtOrTrunc(V, SelType);
158  V = Builder.CreateShl(V, ValZeros - AndZeros);
159  } else if (ValZeros < AndZeros) {
160  V = Builder.CreateLShr(V, AndZeros - ValZeros);
161  V = Builder.CreateZExtOrTrunc(V, SelType);
162  } else {
163  V = Builder.CreateZExtOrTrunc(V, SelType);
164  }
165 
166  // Okay, now we know that everything is set up, we just don't know whether we
167  // have a icmp_ne or icmp_eq and whether the true or false val is the zero.
168  bool ShouldNotVal = !TC.isNullValue();
169  ShouldNotVal ^= Pred == ICmpInst::ICMP_NE;
170  if (ShouldNotVal)
171  V = Builder.CreateXor(V, ValC);
172 
173  return V;
174 }
175 
176 /// We want to turn code that looks like this:
177 /// %C = or %A, %B
178 /// %D = select %cond, %C, %A
179 /// into:
180 /// %C = select %cond, %B, 0
181 /// %D = or %A, %C
182 ///
183 /// Assuming that the specified instruction is an operand to the select, return
184 /// a bitmask indicating which operands of this instruction are foldable if they
185 /// equal the other incoming value of the select.
187  switch (I->getOpcode()) {
188  case Instruction::Add:
189  case Instruction::Mul:
190  case Instruction::And:
191  case Instruction::Or:
192  case Instruction::Xor:
193  return 3; // Can fold through either operand.
194  case Instruction::Sub: // Can only fold on the amount subtracted.
195  case Instruction::Shl: // Can only fold on the shift amount.
196  case Instruction::LShr:
197  case Instruction::AShr:
198  return 1;
199  default:
200  return 0; // Cannot fold
201  }
202 }
203 
204 /// For the same transformation as the previous function, return the identity
205 /// constant that goes into the select.
207  switch (I->getOpcode()) {
208  default: llvm_unreachable("This cannot happen!");
209  case Instruction::Add:
210  case Instruction::Sub:
211  case Instruction::Or:
212  case Instruction::Xor:
213  case Instruction::Shl:
214  case Instruction::LShr:
215  case Instruction::AShr:
217  case Instruction::And:
219  case Instruction::Mul:
220  return APInt(I->getType()->getScalarSizeInBits(), 1);
221  }
222 }
223 
224 /// We have (select c, TI, FI), and we know that TI and FI have the same opcode.
225 Instruction *InstCombiner::foldSelectOpOp(SelectInst &SI, Instruction *TI,
226  Instruction *FI) {
227  // Don't break up min/max patterns. The hasOneUse checks below prevent that
228  // for most cases, but vector min/max with bitcasts can be transformed. If the
229  // one-use restrictions are eased for other patterns, we still don't want to
230  // obfuscate min/max.
231  if ((match(&SI, m_SMin(m_Value(), m_Value())) ||
232  match(&SI, m_SMax(m_Value(), m_Value())) ||
233  match(&SI, m_UMin(m_Value(), m_Value())) ||
234  match(&SI, m_UMax(m_Value(), m_Value()))))
235  return nullptr;
236 
237  // If this is a cast from the same type, merge.
238  if (TI->getNumOperands() == 1 && TI->isCast()) {
239  Type *FIOpndTy = FI->getOperand(0)->getType();
240  if (TI->getOperand(0)->getType() != FIOpndTy)
241  return nullptr;
242 
243  // The select condition may be a vector. We may only change the operand
244  // type if the vector width remains the same (and matches the condition).
245  Type *CondTy = SI.getCondition()->getType();
246  if (CondTy->isVectorTy()) {
247  if (!FIOpndTy->isVectorTy())
248  return nullptr;
249  if (CondTy->getVectorNumElements() != FIOpndTy->getVectorNumElements())
250  return nullptr;
251 
252  // TODO: If the backend knew how to deal with casts better, we could
253  // remove this limitation. For now, there's too much potential to create
254  // worse codegen by promoting the select ahead of size-altering casts
255  // (PR28160).
256  //
257  // Note that ValueTracking's matchSelectPattern() looks through casts
258  // without checking 'hasOneUse' when it matches min/max patterns, so this
259  // transform may end up happening anyway.
260  if (TI->getOpcode() != Instruction::BitCast &&
261  (!TI->hasOneUse() || !FI->hasOneUse()))
262  return nullptr;
263  } else if (!TI->hasOneUse() || !FI->hasOneUse()) {
264  // TODO: The one-use restrictions for a scalar select could be eased if
265  // the fold of a select in visitLoadInst() was enhanced to match a pattern
266  // that includes a cast.
267  return nullptr;
268  }
269 
270  // Fold this by inserting a select from the input values.
271  Value *NewSI =
272  Builder.CreateSelect(SI.getCondition(), TI->getOperand(0),
273  FI->getOperand(0), SI.getName() + ".v", &SI);
274  return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
275  TI->getType());
276  }
277 
278  // Only handle binary operators (including two-operand getelementptr) with
279  // one-use here. As with the cast case above, it may be possible to relax the
280  // one-use constraint, but that needs be examined carefully since it may not
281  // reduce the total number of instructions.
282  if (TI->getNumOperands() != 2 || FI->getNumOperands() != 2 ||
283  (!isa<BinaryOperator>(TI) && !isa<GetElementPtrInst>(TI)) ||
284  !TI->hasOneUse() || !FI->hasOneUse())
285  return nullptr;
286 
287  // Figure out if the operations have any operands in common.
288  Value *MatchOp, *OtherOpT, *OtherOpF;
289  bool MatchIsOpZero;
290  if (TI->getOperand(0) == FI->getOperand(0)) {
291  MatchOp = TI->getOperand(0);
292  OtherOpT = TI->getOperand(1);
293  OtherOpF = FI->getOperand(1);
294  MatchIsOpZero = true;
295  } else if (TI->getOperand(1) == FI->getOperand(1)) {
296  MatchOp = TI->getOperand(1);
297  OtherOpT = TI->getOperand(0);
298  OtherOpF = FI->getOperand(0);
299  MatchIsOpZero = false;
300  } else if (!TI->isCommutative()) {
301  return nullptr;
302  } else if (TI->getOperand(0) == FI->getOperand(1)) {
303  MatchOp = TI->getOperand(0);
304  OtherOpT = TI->getOperand(1);
305  OtherOpF = FI->getOperand(0);
306  MatchIsOpZero = true;
307  } else if (TI->getOperand(1) == FI->getOperand(0)) {
308  MatchOp = TI->getOperand(1);
309  OtherOpT = TI->getOperand(0);
310  OtherOpF = FI->getOperand(1);
311  MatchIsOpZero = true;
312  } else {
313  return nullptr;
314  }
315 
316  // If we reach here, they do have operations in common.
317  Value *NewSI = Builder.CreateSelect(SI.getCondition(), OtherOpT, OtherOpF,
318  SI.getName() + ".v", &SI);
319  Value *Op0 = MatchIsOpZero ? MatchOp : NewSI;
320  Value *Op1 = MatchIsOpZero ? NewSI : MatchOp;
321  if (auto *BO = dyn_cast<BinaryOperator>(TI)) {
322  return BinaryOperator::Create(BO->getOpcode(), Op0, Op1);
323  }
324  if (auto *TGEP = dyn_cast<GetElementPtrInst>(TI)) {
325  auto *FGEP = cast<GetElementPtrInst>(FI);
326  Type *ElementType = TGEP->getResultElementType();
327  return TGEP->isInBounds() && FGEP->isInBounds()
328  ? GetElementPtrInst::CreateInBounds(ElementType, Op0, {Op1})
329  : GetElementPtrInst::Create(ElementType, Op0, {Op1});
330  }
331  llvm_unreachable("Expected BinaryOperator or GEP");
332  return nullptr;
333 }
334 
335 static bool isSelect01(const APInt &C1I, const APInt &C2I) {
336  if (!C1I.isNullValue() && !C2I.isNullValue()) // One side must be zero.
337  return false;
338  return C1I.isOneValue() || C1I.isAllOnesValue() ||
339  C2I.isOneValue() || C2I.isAllOnesValue();
340 }
341 
342 /// Try to fold the select into one of the operands to allow further
343 /// optimization.
344 Instruction *InstCombiner::foldSelectIntoOp(SelectInst &SI, Value *TrueVal,
345  Value *FalseVal) {
346  // See the comment above GetSelectFoldableOperands for a description of the
347  // transformation we are doing here.
348  if (auto *TVI = dyn_cast<BinaryOperator>(TrueVal)) {
349  if (TVI->hasOneUse() && !isa<Constant>(FalseVal)) {
350  if (unsigned SFO = getSelectFoldableOperands(TVI)) {
351  unsigned OpToFold = 0;
352  if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
353  OpToFold = 1;
354  } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
355  OpToFold = 2;
356  }
357 
358  if (OpToFold) {
360  Value *OOp = TVI->getOperand(2-OpToFold);
361  // Avoid creating select between 2 constants unless it's selecting
362  // between 0, 1 and -1.
363  const APInt *OOpC;
364  bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
365  if (!isa<Constant>(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) {
366  Value *C = ConstantInt::get(OOp->getType(), CI);
367  Value *NewSel = Builder.CreateSelect(SI.getCondition(), OOp, C);
368  NewSel->takeName(TVI);
369  BinaryOperator *BO = BinaryOperator::Create(TVI->getOpcode(),
370  FalseVal, NewSel);
371  BO->copyIRFlags(TVI);
372  return BO;
373  }
374  }
375  }
376  }
377  }
378 
379  if (auto *FVI = dyn_cast<BinaryOperator>(FalseVal)) {
380  if (FVI->hasOneUse() && !isa<Constant>(TrueVal)) {
381  if (unsigned SFO = getSelectFoldableOperands(FVI)) {
382  unsigned OpToFold = 0;
383  if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
384  OpToFold = 1;
385  } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
386  OpToFold = 2;
387  }
388 
389  if (OpToFold) {
391  Value *OOp = FVI->getOperand(2-OpToFold);
392  // Avoid creating select between 2 constants unless it's selecting
393  // between 0, 1 and -1.
394  const APInt *OOpC;
395  bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
396  if (!isa<Constant>(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) {
397  Value *C = ConstantInt::get(OOp->getType(), CI);
398  Value *NewSel = Builder.CreateSelect(SI.getCondition(), C, OOp);
399  NewSel->takeName(FVI);
400  BinaryOperator *BO = BinaryOperator::Create(FVI->getOpcode(),
401  TrueVal, NewSel);
402  BO->copyIRFlags(FVI);
403  return BO;
404  }
405  }
406  }
407  }
408  }
409 
410  return nullptr;
411 }
412 
413 /// We want to turn:
414 /// (select (icmp eq (and X, Y), 0), (and (lshr X, Z), 1), 1)
415 /// into:
416 /// zext (icmp ne i32 (and X, (or Y, (shl 1, Z))), 0)
417 /// Note:
418 /// Z may be 0 if lshr is missing.
419 /// Worst-case scenario is that we will replace 5 instructions with 5 different
420 /// instructions, but we got rid of select.
421 static Instruction *foldSelectICmpAndAnd(Type *SelType, const ICmpInst *Cmp,
422  Value *TVal, Value *FVal,
423  InstCombiner::BuilderTy &Builder) {
424  if (!(Cmp->hasOneUse() && Cmp->getOperand(0)->hasOneUse() &&
425  Cmp->getPredicate() == ICmpInst::ICMP_EQ &&
426  match(Cmp->getOperand(1), m_Zero()) && match(FVal, m_One())))
427  return nullptr;
428 
429  // The TrueVal has general form of: and %B, 1
430  Value *B;
431  if (!match(TVal, m_OneUse(m_And(m_Value(B), m_One()))))
432  return nullptr;
433 
434  // Where %B may be optionally shifted: lshr %X, %Z.
435  Value *X, *Z;
436  const bool HasShift = match(B, m_OneUse(m_LShr(m_Value(X), m_Value(Z))));
437  if (!HasShift)
438  X = B;
439 
440  Value *Y;
441  if (!match(Cmp->getOperand(0), m_c_And(m_Specific(X), m_Value(Y))))
442  return nullptr;
443 
444  // ((X & Y) == 0) ? ((X >> Z) & 1) : 1 --> (X & (Y | (1 << Z))) != 0
445  // ((X & Y) == 0) ? (X & 1) : 1 --> (X & (Y | 1)) != 0
446  Constant *One = ConstantInt::get(SelType, 1);
447  Value *MaskB = HasShift ? Builder.CreateShl(One, Z) : One;
448  Value *FullMask = Builder.CreateOr(Y, MaskB);
449  Value *MaskedX = Builder.CreateAnd(X, FullMask);
450  Value *ICmpNeZero = Builder.CreateIsNotNull(MaskedX);
451  return new ZExtInst(ICmpNeZero, SelType);
452 }
453 
454 /// We want to turn:
455 /// (select (icmp eq (and X, C1), 0), Y, (or Y, C2))
456 /// into:
457 /// (or (shl (and X, C1), C3), Y)
458 /// iff:
459 /// C1 and C2 are both powers of 2
460 /// where:
461 /// C3 = Log(C2) - Log(C1)
462 ///
463 /// This transform handles cases where:
464 /// 1. The icmp predicate is inverted
465 /// 2. The select operands are reversed
466 /// 3. The magnitude of C2 and C1 are flipped
467 static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal,
468  Value *FalseVal,
469  InstCombiner::BuilderTy &Builder) {
470  // Only handle integer compares. Also, if this is a vector select, we need a
471  // vector compare.
472  if (!TrueVal->getType()->isIntOrIntVectorTy() ||
473  TrueVal->getType()->isVectorTy() != IC->getType()->isVectorTy())
474  return nullptr;
475 
476  Value *CmpLHS = IC->getOperand(0);
477  Value *CmpRHS = IC->getOperand(1);
478 
479  Value *V;
480  unsigned C1Log;
481  bool IsEqualZero;
482  bool NeedAnd = false;
483  if (IC->isEquality()) {
484  if (!match(CmpRHS, m_Zero()))
485  return nullptr;
486 
487  const APInt *C1;
488  if (!match(CmpLHS, m_And(m_Value(), m_Power2(C1))))
489  return nullptr;
490 
491  V = CmpLHS;
492  C1Log = C1->logBase2();
493  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ;
494  } else if (IC->getPredicate() == ICmpInst::ICMP_SLT ||
495  IC->getPredicate() == ICmpInst::ICMP_SGT) {
496  // We also need to recognize (icmp slt (trunc (X)), 0) and
497  // (icmp sgt (trunc (X)), -1).
498  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_SGT;
499  if ((IsEqualZero && !match(CmpRHS, m_AllOnes())) ||
500  (!IsEqualZero && !match(CmpRHS, m_Zero())))
501  return nullptr;
502 
503  if (!match(CmpLHS, m_OneUse(m_Trunc(m_Value(V)))))
504  return nullptr;
505 
506  C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1;
507  NeedAnd = true;
508  } else {
509  return nullptr;
510  }
511 
512  const APInt *C2;
513  bool OrOnTrueVal = false;
514  bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)));
515  if (!OrOnFalseVal)
516  OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2)));
517 
518  if (!OrOnFalseVal && !OrOnTrueVal)
519  return nullptr;
520 
521  Value *Y = OrOnFalseVal ? TrueVal : FalseVal;
522 
523  unsigned C2Log = C2->logBase2();
524 
525  bool NeedXor = (!IsEqualZero && OrOnFalseVal) || (IsEqualZero && OrOnTrueVal);
526  bool NeedShift = C1Log != C2Log;
527  bool NeedZExtTrunc = Y->getType()->getScalarSizeInBits() !=
529 
530  // Make sure we don't create more instructions than we save.
531  Value *Or = OrOnFalseVal ? FalseVal : TrueVal;
532  if ((NeedShift + NeedXor + NeedZExtTrunc) >
533  (IC->hasOneUse() + Or->hasOneUse()))
534  return nullptr;
535 
536  if (NeedAnd) {
537  // Insert the AND instruction on the input to the truncate.
539  V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), C1));
540  }
541 
542  if (C2Log > C1Log) {
543  V = Builder.CreateZExtOrTrunc(V, Y->getType());
544  V = Builder.CreateShl(V, C2Log - C1Log);
545  } else if (C1Log > C2Log) {
546  V = Builder.CreateLShr(V, C1Log - C2Log);
547  V = Builder.CreateZExtOrTrunc(V, Y->getType());
548  } else
549  V = Builder.CreateZExtOrTrunc(V, Y->getType());
550 
551  if (NeedXor)
552  V = Builder.CreateXor(V, *C2);
553 
554  return Builder.CreateOr(V, Y);
555 }
556 
557 /// Transform patterns such as: (a > b) ? a - b : 0
558 /// into: ((a > b) ? a : b) - b)
559 /// This produces a canonical max pattern that is more easily recognized by the
560 /// backend and converted into saturated subtraction instructions if those
561 /// exist.
562 /// There are 8 commuted/swapped variants of this pattern.
563 /// TODO: Also support a - UMIN(a,b) patterns.
565  const Value *TrueVal,
566  const Value *FalseVal,
567  InstCombiner::BuilderTy &Builder) {
568  ICmpInst::Predicate Pred = ICI->getPredicate();
569  if (!ICmpInst::isUnsigned(Pred))
570  return nullptr;
571 
572  // (b > a) ? 0 : a - b -> (b <= a) ? a - b : 0
573  if (match(TrueVal, m_Zero())) {
574  Pred = ICmpInst::getInversePredicate(Pred);
575  std::swap(TrueVal, FalseVal);
576  }
577  if (!match(FalseVal, m_Zero()))
578  return nullptr;
579 
580  Value *A = ICI->getOperand(0);
581  Value *B = ICI->getOperand(1);
582  if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_ULT) {
583  // (b < a) ? a - b : 0 -> (a > b) ? a - b : 0
584  std::swap(A, B);
585  Pred = ICmpInst::getSwappedPredicate(Pred);
586  }
587 
588  assert((Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_UGT) &&
589  "Unexpected isUnsigned predicate!");
590 
591  // Account for swapped form of subtraction: ((a > b) ? b - a : 0).
592  bool IsNegative = false;
593  if (match(TrueVal, m_Sub(m_Specific(B), m_Specific(A))))
594  IsNegative = true;
595  else if (!match(TrueVal, m_Sub(m_Specific(A), m_Specific(B))))
596  return nullptr;
597 
598  // If sub is used anywhere else, we wouldn't be able to eliminate it
599  // afterwards.
600  if (!TrueVal->hasOneUse())
601  return nullptr;
602 
603  // All checks passed, convert to canonical unsigned saturated subtraction
604  // form: sub(max()).
605  // (a > b) ? a - b : 0 -> ((a > b) ? a : b) - b)
606  Value *Max = Builder.CreateSelect(Builder.CreateICmp(Pred, A, B), A, B);
607  return IsNegative ? Builder.CreateSub(B, Max) : Builder.CreateSub(Max, B);
608 }
609 
610 /// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single
611 /// call to cttz/ctlz with flag 'is_zero_undef' cleared.
612 ///
613 /// For example, we can fold the following code sequence:
614 /// \code
615 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
616 /// %1 = icmp ne i32 %x, 0
617 /// %2 = select i1 %1, i32 %0, i32 32
618 /// \code
619 ///
620 /// into:
621 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
622 static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
623  InstCombiner::BuilderTy &Builder) {
624  ICmpInst::Predicate Pred = ICI->getPredicate();
625  Value *CmpLHS = ICI->getOperand(0);
626  Value *CmpRHS = ICI->getOperand(1);
627 
628  // Check if the condition value compares a value for equality against zero.
629  if (!ICI->isEquality() || !match(CmpRHS, m_Zero()))
630  return nullptr;
631 
632  Value *Count = FalseVal;
633  Value *ValueOnZero = TrueVal;
634  if (Pred == ICmpInst::ICMP_NE)
635  std::swap(Count, ValueOnZero);
636 
637  // Skip zero extend/truncate.
638  Value *V = nullptr;
639  if (match(Count, m_ZExt(m_Value(V))) ||
640  match(Count, m_Trunc(m_Value(V))))
641  Count = V;
642 
643  // Check if the value propagated on zero is a constant number equal to the
644  // sizeof in bits of 'Count'.
645  unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits();
646  if (!match(ValueOnZero, m_SpecificInt(SizeOfInBits)))
647  return nullptr;
648 
649  // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
650  // input to the cttz/ctlz is used as LHS for the compare instruction.
651  if (match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) ||
652  match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS)))) {
653  IntrinsicInst *II = cast<IntrinsicInst>(Count);
654  // Explicitly clear the 'undef_on_zero' flag.
655  IntrinsicInst *NewI = cast<IntrinsicInst>(II->clone());
656  NewI->setArgOperand(1, ConstantInt::getFalse(NewI->getContext()));
657  Builder.Insert(NewI);
658  return Builder.CreateZExtOrTrunc(NewI, ValueOnZero->getType());
659  }
660 
661  return nullptr;
662 }
663 
664 /// Return true if we find and adjust an icmp+select pattern where the compare
665 /// is with a constant that can be incremented or decremented to match the
666 /// minimum or maximum idiom.
667 static bool adjustMinMax(SelectInst &Sel, ICmpInst &Cmp) {
668  ICmpInst::Predicate Pred = Cmp.getPredicate();
669  Value *CmpLHS = Cmp.getOperand(0);
670  Value *CmpRHS = Cmp.getOperand(1);
671  Value *TrueVal = Sel.getTrueValue();
672  Value *FalseVal = Sel.getFalseValue();
673 
674  // We may move or edit the compare, so make sure the select is the only user.
675  const APInt *CmpC;
676  if (!Cmp.hasOneUse() || !match(CmpRHS, m_APInt(CmpC)))
677  return false;
678 
679  // These transforms only work for selects of integers or vector selects of
680  // integer vectors.
681  Type *SelTy = Sel.getType();
682  auto *SelEltTy = dyn_cast<IntegerType>(SelTy->getScalarType());
683  if (!SelEltTy || SelTy->isVectorTy() != Cmp.getType()->isVectorTy())
684  return false;
685 
686  Constant *AdjustedRHS;
687  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT)
688  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC + 1);
689  else if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT)
690  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC - 1);
691  else
692  return false;
693 
694  // X > C ? X : C+1 --> X < C+1 ? C+1 : X
695  // X < C ? X : C-1 --> X > C-1 ? C-1 : X
696  if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
697  (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
698  ; // Nothing to do here. Values match without any sign/zero extension.
699  }
700  // Types do not match. Instead of calculating this with mixed types, promote
701  // all to the larger type. This enables scalar evolution to analyze this
702  // expression.
703  else if (CmpRHS->getType()->getScalarSizeInBits() < SelEltTy->getBitWidth()) {
704  Constant *SextRHS = ConstantExpr::getSExt(AdjustedRHS, SelTy);
705 
706  // X = sext x; x >s c ? X : C+1 --> X = sext x; X <s C+1 ? C+1 : X
707  // X = sext x; x <s c ? X : C-1 --> X = sext x; X >s C-1 ? C-1 : X
708  // X = sext x; x >u c ? X : C+1 --> X = sext x; X <u C+1 ? C+1 : X
709  // X = sext x; x <u c ? X : C-1 --> X = sext x; X >u C-1 ? C-1 : X
710  if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) && SextRHS == FalseVal) {
711  CmpLHS = TrueVal;
712  AdjustedRHS = SextRHS;
713  } else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) &&
714  SextRHS == TrueVal) {
715  CmpLHS = FalseVal;
716  AdjustedRHS = SextRHS;
717  } else if (Cmp.isUnsigned()) {
718  Constant *ZextRHS = ConstantExpr::getZExt(AdjustedRHS, SelTy);
719  // X = zext x; x >u c ? X : C+1 --> X = zext x; X <u C+1 ? C+1 : X
720  // X = zext x; x <u c ? X : C-1 --> X = zext x; X >u C-1 ? C-1 : X
721  // zext + signed compare cannot be changed:
722  // 0xff <s 0x00, but 0x00ff >s 0x0000
723  if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) && ZextRHS == FalseVal) {
724  CmpLHS = TrueVal;
725  AdjustedRHS = ZextRHS;
726  } else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) &&
727  ZextRHS == TrueVal) {
728  CmpLHS = FalseVal;
729  AdjustedRHS = ZextRHS;
730  } else {
731  return false;
732  }
733  } else {
734  return false;
735  }
736  } else {
737  return false;
738  }
739 
740  Pred = ICmpInst::getSwappedPredicate(Pred);
741  CmpRHS = AdjustedRHS;
742  std::swap(FalseVal, TrueVal);
743  Cmp.setPredicate(Pred);
744  Cmp.setOperand(0, CmpLHS);
745  Cmp.setOperand(1, CmpRHS);
746  Sel.setOperand(1, TrueVal);
747  Sel.setOperand(2, FalseVal);
748  Sel.swapProfMetadata();
749 
750  // Move the compare instruction right before the select instruction. Otherwise
751  // the sext/zext value may be defined after the compare instruction uses it.
752  Cmp.moveBefore(&Sel);
753 
754  return true;
755 }
756 
757 /// If this is an integer min/max (icmp + select) with a constant operand,
758 /// create the canonical icmp for the min/max operation and canonicalize the
759 /// constant to the 'false' operand of the select:
760 /// select (icmp Pred X, C1), C2, X --> select (icmp Pred' X, C2), X, C2
761 /// Note: if C1 != C2, this will change the icmp constant to the existing
762 /// constant operand of the select.
763 static Instruction *
764 canonicalizeMinMaxWithConstant(SelectInst &Sel, ICmpInst &Cmp,
765  InstCombiner::BuilderTy &Builder) {
766  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
767  return nullptr;
768 
769  // Canonicalize the compare predicate based on whether we have min or max.
770  Value *LHS, *RHS;
771  SelectPatternResult SPR = matchSelectPattern(&Sel, LHS, RHS);
773  return nullptr;
774 
775  // Is this already canonical?
776  ICmpInst::Predicate CanonicalPred = getMinMaxPred(SPR.Flavor);
777  if (Cmp.getOperand(0) == LHS && Cmp.getOperand(1) == RHS &&
778  Cmp.getPredicate() == CanonicalPred)
779  return nullptr;
780 
781  // Create the canonical compare and plug it into the select.
782  Sel.setCondition(Builder.CreateICmp(CanonicalPred, LHS, RHS));
783 
784  // If the select operands did not change, we're done.
785  if (Sel.getTrueValue() == LHS && Sel.getFalseValue() == RHS)
786  return &Sel;
787 
788  // If we are swapping the select operands, swap the metadata too.
789  assert(Sel.getTrueValue() == RHS && Sel.getFalseValue() == LHS &&
790  "Unexpected results from matchSelectPattern");
791  Sel.setTrueValue(LHS);
792  Sel.setFalseValue(RHS);
793  Sel.swapProfMetadata();
794  return &Sel;
795 }
796 
797 /// There are 4 select variants for each of ABS/NABS (different compare
798 /// constants, compare predicates, select operands). Canonicalize to 1 pattern.
799 /// This makes CSE more likely.
800 static Instruction *canonicalizeAbsNabs(SelectInst &Sel, ICmpInst &Cmp,
801  InstCombiner::BuilderTy &Builder) {
802  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
803  return nullptr;
804 
805  // Choose a sign-bit check for the compare (likely simpler for codegen).
806  // ABS: (X <s 0) ? -X : X
807  // NABS: (X <s 0) ? X : -X
808  Value *LHS, *RHS;
809  SelectPatternFlavor SPF = matchSelectPattern(&Sel, LHS, RHS).Flavor;
810  if (SPF != SelectPatternFlavor::SPF_ABS &&
812  return nullptr;
813 
814  // Is this already canonical?
815  if (match(Cmp.getOperand(1), m_ZeroInt()) &&
817  return nullptr;
818 
819  // Create the canonical compare.
822 
823  // If the select operands do not change, we're done.
824  Value *TVal = Sel.getTrueValue();
825  Value *FVal = Sel.getFalseValue();
826  if (SPF == SelectPatternFlavor::SPF_NABS) {
827  if (TVal == LHS && match(FVal, m_Neg(m_Specific(TVal))))
828  return &Sel;
829  assert(FVal == LHS && match(TVal, m_Neg(m_Specific(FVal))) &&
830  "Unexpected results from matchSelectPattern");
831  } else {
832  if (FVal == LHS && match(TVal, m_Neg(m_Specific(FVal))))
833  return &Sel;
834  assert(TVal == LHS && match(FVal, m_Neg(m_Specific(TVal))) &&
835  "Unexpected results from matchSelectPattern");
836  }
837 
838  // We are swapping the select operands, so swap the metadata too.
839  Sel.setTrueValue(FVal);
840  Sel.setFalseValue(TVal);
841  Sel.swapProfMetadata();
842  return &Sel;
843 }
844 
845 /// Visit a SelectInst that has an ICmpInst as its first operand.
846 Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI,
847  ICmpInst *ICI) {
848  Value *TrueVal = SI.getTrueValue();
849  Value *FalseVal = SI.getFalseValue();
850 
851  if (Instruction *NewSel = canonicalizeMinMaxWithConstant(SI, *ICI, Builder))
852  return NewSel;
853 
854  if (Instruction *NewAbs = canonicalizeAbsNabs(SI, *ICI, Builder))
855  return NewAbs;
856 
857  bool Changed = adjustMinMax(SI, *ICI);
858 
859  if (Value *V = foldSelectICmpAnd(SI, ICI, Builder))
860  return replaceInstUsesWith(SI, V);
861 
862  // NOTE: if we wanted to, this is where to detect integer MIN/MAX
863  ICmpInst::Predicate Pred = ICI->getPredicate();
864  Value *CmpLHS = ICI->getOperand(0);
865  Value *CmpRHS = ICI->getOperand(1);
866  if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
867  if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
868  // Transform (X == C) ? X : Y -> (X == C) ? C : Y
869  SI.setOperand(1, CmpRHS);
870  Changed = true;
871  } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
872  // Transform (X != C) ? Y : X -> (X != C) ? Y : C
873  SI.setOperand(2, CmpRHS);
874  Changed = true;
875  }
876  }
877 
878  // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring
879  // decomposeBitTestICmp() might help.
880  {
881  unsigned BitWidth =
882  DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
883  APInt MinSignedValue = APInt::getSignedMinValue(BitWidth);
884  Value *X;
885  const APInt *Y, *C;
886  bool TrueWhenUnset;
887  bool IsBitTest = false;
888  if (ICmpInst::isEquality(Pred) &&
889  match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) &&
890  match(CmpRHS, m_Zero())) {
891  IsBitTest = true;
892  TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
893  } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
894  X = CmpLHS;
895  Y = &MinSignedValue;
896  IsBitTest = true;
897  TrueWhenUnset = false;
898  } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
899  X = CmpLHS;
900  Y = &MinSignedValue;
901  IsBitTest = true;
902  TrueWhenUnset = true;
903  }
904  if (IsBitTest) {
905  Value *V = nullptr;
906  // (X & Y) == 0 ? X : X ^ Y --> X & ~Y
907  if (TrueWhenUnset && TrueVal == X &&
908  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
909  V = Builder.CreateAnd(X, ~(*Y));
910  // (X & Y) != 0 ? X ^ Y : X --> X & ~Y
911  else if (!TrueWhenUnset && FalseVal == X &&
912  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
913  V = Builder.CreateAnd(X, ~(*Y));
914  // (X & Y) == 0 ? X ^ Y : X --> X | Y
915  else if (TrueWhenUnset && FalseVal == X &&
916  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
917  V = Builder.CreateOr(X, *Y);
918  // (X & Y) != 0 ? X : X ^ Y --> X | Y
919  else if (!TrueWhenUnset && TrueVal == X &&
920  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
921  V = Builder.CreateOr(X, *Y);
922 
923  if (V)
924  return replaceInstUsesWith(SI, V);
925  }
926  }
927 
928  if (Instruction *V =
929  foldSelectICmpAndAnd(SI.getType(), ICI, TrueVal, FalseVal, Builder))
930  return V;
931 
932  if (Value *V = foldSelectICmpAndOr(ICI, TrueVal, FalseVal, Builder))
933  return replaceInstUsesWith(SI, V);
934 
935  if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
936  return replaceInstUsesWith(SI, V);
937 
938  if (Value *V = canonicalizeSaturatedSubtract(ICI, TrueVal, FalseVal, Builder))
939  return replaceInstUsesWith(SI, V);
940 
941  return Changed ? &SI : nullptr;
942 }
943 
944 /// SI is a select whose condition is a PHI node (but the two may be in
945 /// different blocks). See if the true/false values (V) are live in all of the
946 /// predecessor blocks of the PHI. For example, cases like this can't be mapped:
947 ///
948 /// X = phi [ C1, BB1], [C2, BB2]
949 /// Y = add
950 /// Z = select X, Y, 0
951 ///
952 /// because Y is not live in BB1/BB2.
953 static bool canSelectOperandBeMappingIntoPredBlock(const Value *V,
954  const SelectInst &SI) {
955  // If the value is a non-instruction value like a constant or argument, it
956  // can always be mapped.
957  const Instruction *I = dyn_cast<Instruction>(V);
958  if (!I) return true;
959 
960  // If V is a PHI node defined in the same block as the condition PHI, we can
961  // map the arguments.
962  const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
963 
964  if (const PHINode *VP = dyn_cast<PHINode>(I))
965  if (VP->getParent() == CondPHI->getParent())
966  return true;
967 
968  // Otherwise, if the PHI and select are defined in the same block and if V is
969  // defined in a different block, then we can transform it.
970  if (SI.getParent() == CondPHI->getParent() &&
971  I->getParent() != CondPHI->getParent())
972  return true;
973 
974  // Otherwise we have a 'hard' case and we can't tell without doing more
975  // detailed dominator based analysis, punt.
976  return false;
977 }
978 
979 /// We have an SPF (e.g. a min or max) of an SPF of the form:
980 /// SPF2(SPF1(A, B), C)
981 Instruction *InstCombiner::foldSPFofSPF(Instruction *Inner,
982  SelectPatternFlavor SPF1,
983  Value *A, Value *B,
984  Instruction &Outer,
985  SelectPatternFlavor SPF2, Value *C) {
986  if (Outer.getType() != Inner->getType())
987  return nullptr;
988 
989  if (C == A || C == B) {
990  // MAX(MAX(A, B), B) -> MAX(A, B)
991  // MIN(MIN(a, b), a) -> MIN(a, b)
992  if (SPF1 == SPF2 && SelectPatternResult::isMinOrMax(SPF1))
993  return replaceInstUsesWith(Outer, Inner);
994 
995  // MAX(MIN(a, b), a) -> a
996  // MIN(MAX(a, b), a) -> a
997  if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
998  (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
999  (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
1000  (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
1001  return replaceInstUsesWith(Outer, C);
1002  }
1003 
1004  if (SPF1 == SPF2) {
1005  const APInt *CB, *CC;
1006  if (match(B, m_APInt(CB)) && match(C, m_APInt(CC))) {
1007  // MIN(MIN(A, 23), 97) -> MIN(A, 23)
1008  // MAX(MAX(A, 97), 23) -> MAX(A, 97)
1009  if ((SPF1 == SPF_UMIN && CB->ule(*CC)) ||
1010  (SPF1 == SPF_SMIN && CB->sle(*CC)) ||
1011  (SPF1 == SPF_UMAX && CB->uge(*CC)) ||
1012  (SPF1 == SPF_SMAX && CB->sge(*CC)))
1013  return replaceInstUsesWith(Outer, Inner);
1014 
1015  // MIN(MIN(A, 97), 23) -> MIN(A, 23)
1016  // MAX(MAX(A, 23), 97) -> MAX(A, 97)
1017  if ((SPF1 == SPF_UMIN && CB->ugt(*CC)) ||
1018  (SPF1 == SPF_SMIN && CB->sgt(*CC)) ||
1019  (SPF1 == SPF_UMAX && CB->ult(*CC)) ||
1020  (SPF1 == SPF_SMAX && CB->slt(*CC))) {
1021  Outer.replaceUsesOfWith(Inner, A);
1022  return &Outer;
1023  }
1024  }
1025  }
1026 
1027  // ABS(ABS(X)) -> ABS(X)
1028  // NABS(NABS(X)) -> NABS(X)
1029  if (SPF1 == SPF2 && (SPF1 == SPF_ABS || SPF1 == SPF_NABS)) {
1030  return replaceInstUsesWith(Outer, Inner);
1031  }
1032 
1033  // ABS(NABS(X)) -> ABS(X)
1034  // NABS(ABS(X)) -> NABS(X)
1035  if ((SPF1 == SPF_ABS && SPF2 == SPF_NABS) ||
1036  (SPF1 == SPF_NABS && SPF2 == SPF_ABS)) {
1037  SelectInst *SI = cast<SelectInst>(Inner);
1038  Value *NewSI =
1039  Builder.CreateSelect(SI->getCondition(), SI->getFalseValue(),
1040  SI->getTrueValue(), SI->getName(), SI);
1041  return replaceInstUsesWith(Outer, NewSI);
1042  }
1043 
1044  auto IsFreeOrProfitableToInvert =
1045  [&](Value *V, Value *&NotV, bool &ElidesXor) {
1046  if (match(V, m_Not(m_Value(NotV)))) {
1047  // If V has at most 2 uses then we can get rid of the xor operation
1048  // entirely.
1049  ElidesXor |= !V->hasNUsesOrMore(3);
1050  return true;
1051  }
1052 
1053  if (IsFreeToInvert(V, !V->hasNUsesOrMore(3))) {
1054  NotV = nullptr;
1055  return true;
1056  }
1057 
1058  return false;
1059  };
1060 
1061  Value *NotA, *NotB, *NotC;
1062  bool ElidesXor = false;
1063 
1064  // MIN(MIN(~A, ~B), ~C) == ~MAX(MAX(A, B), C)
1065  // MIN(MAX(~A, ~B), ~C) == ~MAX(MIN(A, B), C)
1066  // MAX(MIN(~A, ~B), ~C) == ~MIN(MAX(A, B), C)
1067  // MAX(MAX(~A, ~B), ~C) == ~MIN(MIN(A, B), C)
1068  //
1069  // This transform is performance neutral if we can elide at least one xor from
1070  // the set of three operands, since we'll be tacking on an xor at the very
1071  // end.
1072  if (SelectPatternResult::isMinOrMax(SPF1) &&
1074  IsFreeOrProfitableToInvert(A, NotA, ElidesXor) &&
1075  IsFreeOrProfitableToInvert(B, NotB, ElidesXor) &&
1076  IsFreeOrProfitableToInvert(C, NotC, ElidesXor) && ElidesXor) {
1077  if (!NotA)
1078  NotA = Builder.CreateNot(A);
1079  if (!NotB)
1080  NotB = Builder.CreateNot(B);
1081  if (!NotC)
1082  NotC = Builder.CreateNot(C);
1083 
1084  Value *NewInner = createMinMax(Builder, getInverseMinMaxFlavor(SPF1), NotA,
1085  NotB);
1086  Value *NewOuter = Builder.CreateNot(
1087  createMinMax(Builder, getInverseMinMaxFlavor(SPF2), NewInner, NotC));
1088  return replaceInstUsesWith(Outer, NewOuter);
1089  }
1090 
1091  return nullptr;
1092 }
1093 
1094 /// Turn select C, (X + Y), (X - Y) --> (X + (select C, Y, (-Y))).
1095 /// This is even legal for FP.
1096 static Instruction *foldAddSubSelect(SelectInst &SI,
1097  InstCombiner::BuilderTy &Builder) {
1098  Value *CondVal = SI.getCondition();
1099  Value *TrueVal = SI.getTrueValue();
1100  Value *FalseVal = SI.getFalseValue();
1101  auto *TI = dyn_cast<Instruction>(TrueVal);
1102  auto *FI = dyn_cast<Instruction>(FalseVal);
1103  if (!TI || !FI || !TI->hasOneUse() || !FI->hasOneUse())
1104  return nullptr;
1105 
1106  Instruction *AddOp = nullptr, *SubOp = nullptr;
1107  if ((TI->getOpcode() == Instruction::Sub &&
1108  FI->getOpcode() == Instruction::Add) ||
1109  (TI->getOpcode() == Instruction::FSub &&
1110  FI->getOpcode() == Instruction::FAdd)) {
1111  AddOp = FI;
1112  SubOp = TI;
1113  } else if ((FI->getOpcode() == Instruction::Sub &&
1114  TI->getOpcode() == Instruction::Add) ||
1115  (FI->getOpcode() == Instruction::FSub &&
1116  TI->getOpcode() == Instruction::FAdd)) {
1117  AddOp = TI;
1118  SubOp = FI;
1119  }
1120 
1121  if (AddOp) {
1122  Value *OtherAddOp = nullptr;
1123  if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
1124  OtherAddOp = AddOp->getOperand(1);
1125  } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
1126  OtherAddOp = AddOp->getOperand(0);
1127  }
1128 
1129  if (OtherAddOp) {
1130  // So at this point we know we have (Y -> OtherAddOp):
1131  // select C, (add X, Y), (sub X, Z)
1132  Value *NegVal; // Compute -Z
1133  if (SI.getType()->isFPOrFPVectorTy()) {
1134  NegVal = Builder.CreateFNeg(SubOp->getOperand(1));
1135  if (Instruction *NegInst = dyn_cast<Instruction>(NegVal)) {
1136  FastMathFlags Flags = AddOp->getFastMathFlags();
1137  Flags &= SubOp->getFastMathFlags();
1138  NegInst->setFastMathFlags(Flags);
1139  }
1140  } else {
1141  NegVal = Builder.CreateNeg(SubOp->getOperand(1));
1142  }
1143 
1144  Value *NewTrueOp = OtherAddOp;
1145  Value *NewFalseOp = NegVal;
1146  if (AddOp != TI)
1147  std::swap(NewTrueOp, NewFalseOp);
1148  Value *NewSel = Builder.CreateSelect(CondVal, NewTrueOp, NewFalseOp,
1149  SI.getName() + ".p", &SI);
1150 
1151  if (SI.getType()->isFPOrFPVectorTy()) {
1152  Instruction *RI =
1153  BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel);
1154 
1155  FastMathFlags Flags = AddOp->getFastMathFlags();
1156  Flags &= SubOp->getFastMathFlags();
1157  RI->setFastMathFlags(Flags);
1158  return RI;
1159  } else
1160  return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
1161  }
1162  }
1163  return nullptr;
1164 }
1165 
1166 Instruction *InstCombiner::foldSelectExtConst(SelectInst &Sel) {
1167  Constant *C;
1168  if (!match(Sel.getTrueValue(), m_Constant(C)) &&
1169  !match(Sel.getFalseValue(), m_Constant(C)))
1170  return nullptr;
1171 
1172  Instruction *ExtInst;
1173  if (!match(Sel.getTrueValue(), m_Instruction(ExtInst)) &&
1174  !match(Sel.getFalseValue(), m_Instruction(ExtInst)))
1175  return nullptr;
1176 
1177  auto ExtOpcode = ExtInst->getOpcode();
1178  if (ExtOpcode != Instruction::ZExt && ExtOpcode != Instruction::SExt)
1179  return nullptr;
1180 
1181  // If we are extending from a boolean type or if we can create a select that
1182  // has the same size operands as its condition, try to narrow the select.
1183  Value *X = ExtInst->getOperand(0);
1184  Type *SmallType = X->getType();
1185  Value *Cond = Sel.getCondition();
1186  auto *Cmp = dyn_cast<CmpInst>(Cond);
1187  if (!SmallType->isIntOrIntVectorTy(1) &&
1188  (!Cmp || Cmp->getOperand(0)->getType() != SmallType))
1189  return nullptr;
1190 
1191  // If the constant is the same after truncation to the smaller type and
1192  // extension to the original type, we can narrow the select.
1193  Type *SelType = Sel.getType();
1194  Constant *TruncC = ConstantExpr::getTrunc(C, SmallType);
1195  Constant *ExtC = ConstantExpr::getCast(ExtOpcode, TruncC, SelType);
1196  if (ExtC == C) {
1197  Value *TruncCVal = cast<Value>(TruncC);
1198  if (ExtInst == Sel.getFalseValue())
1199  std::swap(X, TruncCVal);
1200 
1201  // select Cond, (ext X), C --> ext(select Cond, X, C')
1202  // select Cond, C, (ext X) --> ext(select Cond, C', X)
1203  Value *NewSel = Builder.CreateSelect(Cond, X, TruncCVal, "narrow", &Sel);
1204  return CastInst::Create(Instruction::CastOps(ExtOpcode), NewSel, SelType);
1205  }
1206 
1207  // If one arm of the select is the extend of the condition, replace that arm
1208  // with the extension of the appropriate known bool value.
1209  if (Cond == X) {
1210  if (ExtInst == Sel.getTrueValue()) {
1211  // select X, (sext X), C --> select X, -1, C
1212  // select X, (zext X), C --> select X, 1, C
1213  Constant *One = ConstantInt::getTrue(SmallType);
1214  Constant *AllOnesOrOne = ConstantExpr::getCast(ExtOpcode, One, SelType);
1215  return SelectInst::Create(Cond, AllOnesOrOne, C, "", nullptr, &Sel);
1216  } else {
1217  // select X, C, (sext X) --> select X, C, 0
1218  // select X, C, (zext X) --> select X, C, 0
1219  Constant *Zero = ConstantInt::getNullValue(SelType);
1220  return SelectInst::Create(Cond, C, Zero, "", nullptr, &Sel);
1221  }
1222  }
1223 
1224  return nullptr;
1225 }
1226 
1227 /// Try to transform a vector select with a constant condition vector into a
1228 /// shuffle for easier combining with other shuffles and insert/extract.
1229 static Instruction *canonicalizeSelectToShuffle(SelectInst &SI) {
1230  Value *CondVal = SI.getCondition();
1231  Constant *CondC;
1232  if (!CondVal->getType()->isVectorTy() || !match(CondVal, m_Constant(CondC)))
1233  return nullptr;
1234 
1235  unsigned NumElts = CondVal->getType()->getVectorNumElements();
1237  Mask.reserve(NumElts);
1238  Type *Int32Ty = Type::getInt32Ty(CondVal->getContext());
1239  for (unsigned i = 0; i != NumElts; ++i) {
1240  Constant *Elt = CondC->getAggregateElement(i);
1241  if (!Elt)
1242  return nullptr;
1243 
1244  if (Elt->isOneValue()) {
1245  // If the select condition element is true, choose from the 1st vector.
1246  Mask.push_back(ConstantInt::get(Int32Ty, i));
1247  } else if (Elt->isNullValue()) {
1248  // If the select condition element is false, choose from the 2nd vector.
1249  Mask.push_back(ConstantInt::get(Int32Ty, i + NumElts));
1250  } else if (isa<UndefValue>(Elt)) {
1251  // Undef in a select condition (choose one of the operands) does not mean
1252  // the same thing as undef in a shuffle mask (any value is acceptable), so
1253  // give up.
1254  return nullptr;
1255  } else {
1256  // Bail out on a constant expression.
1257  return nullptr;
1258  }
1259  }
1260 
1261  return new ShuffleVectorInst(SI.getTrueValue(), SI.getFalseValue(),
1262  ConstantVector::get(Mask));
1263 }
1264 
1265 /// Reuse bitcasted operands between a compare and select:
1266 /// select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
1267 /// bitcast (select (cmp (bitcast C), (bitcast D)), (bitcast C), (bitcast D))
1268 static Instruction *foldSelectCmpBitcasts(SelectInst &Sel,
1269  InstCombiner::BuilderTy &Builder) {
1270  Value *Cond = Sel.getCondition();
1271  Value *TVal = Sel.getTrueValue();
1272  Value *FVal = Sel.getFalseValue();
1273 
1274  CmpInst::Predicate Pred;
1275  Value *A, *B;
1276  if (!match(Cond, m_Cmp(Pred, m_Value(A), m_Value(B))))
1277  return nullptr;
1278 
1279  // The select condition is a compare instruction. If the select's true/false
1280  // values are already the same as the compare operands, there's nothing to do.
1281  if (TVal == A || TVal == B || FVal == A || FVal == B)
1282  return nullptr;
1283 
1284  Value *C, *D;
1285  if (!match(A, m_BitCast(m_Value(C))) || !match(B, m_BitCast(m_Value(D))))
1286  return nullptr;
1287 
1288  // select (cmp (bitcast C), (bitcast D)), (bitcast TSrc), (bitcast FSrc)
1289  Value *TSrc, *FSrc;
1290  if (!match(TVal, m_BitCast(m_Value(TSrc))) ||
1291  !match(FVal, m_BitCast(m_Value(FSrc))))
1292  return nullptr;
1293 
1294  // If the select true/false values are *different bitcasts* of the same source
1295  // operands, make the select operands the same as the compare operands and
1296  // cast the result. This is the canonical select form for min/max.
1297  Value *NewSel;
1298  if (TSrc == C && FSrc == D) {
1299  // select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
1300  // bitcast (select (cmp A, B), A, B)
1301  NewSel = Builder.CreateSelect(Cond, A, B, "", &Sel);
1302  } else if (TSrc == D && FSrc == C) {
1303  // select (cmp (bitcast C), (bitcast D)), (bitcast' D), (bitcast' C) -->
1304  // bitcast (select (cmp A, B), B, A)
1305  NewSel = Builder.CreateSelect(Cond, B, A, "", &Sel);
1306  } else {
1307  return nullptr;
1308  }
1309  return CastInst::CreateBitOrPointerCast(NewSel, Sel.getType());
1310 }
1311 
1312 /// Try to eliminate select instructions that test the returned flag of cmpxchg
1313 /// instructions.
1314 ///
1315 /// If a select instruction tests the returned flag of a cmpxchg instruction and
1316 /// selects between the returned value of the cmpxchg instruction its compare
1317 /// operand, the result of the select will always be equal to its false value.
1318 /// For example:
1319 ///
1320 /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst
1321 /// %1 = extractvalue { i64, i1 } %0, 1
1322 /// %2 = extractvalue { i64, i1 } %0, 0
1323 /// %3 = select i1 %1, i64 %compare, i64 %2
1324 /// ret i64 %3
1325 ///
1326 /// The returned value of the cmpxchg instruction (%2) is the original value
1327 /// located at %ptr prior to any update. If the cmpxchg operation succeeds, %2
1328 /// must have been equal to %compare. Thus, the result of the select is always
1329 /// equal to %2, and the code can be simplified to:
1330 ///
1331 /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst
1332 /// %1 = extractvalue { i64, i1 } %0, 0
1333 /// ret i64 %1
1334 ///
1335 static Instruction *foldSelectCmpXchg(SelectInst &SI) {
1336  // A helper that determines if V is an extractvalue instruction whose
1337  // aggregate operand is a cmpxchg instruction and whose single index is equal
1338  // to I. If such conditions are true, the helper returns the cmpxchg
1339  // instruction; otherwise, a nullptr is returned.
1340  auto isExtractFromCmpXchg = [](Value *V, unsigned I) -> AtomicCmpXchgInst * {
1341  auto *Extract = dyn_cast<ExtractValueInst>(V);
1342  if (!Extract)
1343  return nullptr;
1344  if (Extract->getIndices()[0] != I)
1345  return nullptr;
1346  return dyn_cast<AtomicCmpXchgInst>(Extract->getAggregateOperand());
1347  };
1348 
1349  // If the select has a single user, and this user is a select instruction that
1350  // we can simplify, skip the cmpxchg simplification for now.
1351  if (SI.hasOneUse())
1352  if (auto *Select = dyn_cast<SelectInst>(SI.user_back()))
1353  if (Select->getCondition() == SI.getCondition())
1354  if (Select->getFalseValue() == SI.getTrueValue() ||
1355  Select->getTrueValue() == SI.getFalseValue())
1356  return nullptr;
1357 
1358  // Ensure the select condition is the returned flag of a cmpxchg instruction.
1359  auto *CmpXchg = isExtractFromCmpXchg(SI.getCondition(), 1);
1360  if (!CmpXchg)
1361  return nullptr;
1362 
1363  // Check the true value case: The true value of the select is the returned
1364  // value of the same cmpxchg used by the condition, and the false value is the
1365  // cmpxchg instruction's compare operand.
1366  if (auto *X = isExtractFromCmpXchg(SI.getTrueValue(), 0))
1367  if (X == CmpXchg && X->getCompareOperand() == SI.getFalseValue()) {
1368  SI.setTrueValue(SI.getFalseValue());
1369  return &SI;
1370  }
1371 
1372  // Check the false value case: The false value of the select is the returned
1373  // value of the same cmpxchg used by the condition, and the true value is the
1374  // cmpxchg instruction's compare operand.
1375  if (auto *X = isExtractFromCmpXchg(SI.getFalseValue(), 0))
1376  if (X == CmpXchg && X->getCompareOperand() == SI.getTrueValue()) {
1377  SI.setTrueValue(SI.getFalseValue());
1378  return &SI;
1379  }
1380 
1381  return nullptr;
1382 }
1383 
1384 /// Reduce a sequence of min/max with a common operand.
1385 static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS,
1386  Value *RHS,
1387  InstCombiner::BuilderTy &Builder) {
1388  assert(SelectPatternResult::isMinOrMax(SPF) && "Expected a min/max");
1389  // TODO: Allow FP min/max with nnan/nsz.
1390  if (!LHS->getType()->isIntOrIntVectorTy())
1391  return nullptr;
1392 
1393  // Match 3 of the same min/max ops. Example: umin(umin(), umin()).
1394  Value *A, *B, *C, *D;
1395  SelectPatternResult L = matchSelectPattern(LHS, A, B);
1396  SelectPatternResult R = matchSelectPattern(RHS, C, D);
1397  if (SPF != L.Flavor || L.Flavor != R.Flavor)
1398  return nullptr;
1399 
1400  // Look for a common operand. The use checks are different than usual because
1401  // a min/max pattern typically has 2 uses of each op: 1 by the cmp and 1 by
1402  // the select.
1403  Value *MinMaxOp = nullptr;
1404  Value *ThirdOp = nullptr;
1405  if (!LHS->hasNUsesOrMore(3) && RHS->hasNUsesOrMore(3)) {
1406  // If the LHS is only used in this chain and the RHS is used outside of it,
1407  // reuse the RHS min/max because that will eliminate the LHS.
1408  if (D == A || C == A) {
1409  // min(min(a, b), min(c, a)) --> min(min(c, a), b)
1410  // min(min(a, b), min(a, d)) --> min(min(a, d), b)
1411  MinMaxOp = RHS;
1412  ThirdOp = B;
1413  } else if (D == B || C == B) {
1414  // min(min(a, b), min(c, b)) --> min(min(c, b), a)
1415  // min(min(a, b), min(b, d)) --> min(min(b, d), a)
1416  MinMaxOp = RHS;
1417  ThirdOp = A;
1418  }
1419  } else if (!RHS->hasNUsesOrMore(3)) {
1420  // Reuse the LHS. This will eliminate the RHS.
1421  if (D == A || D == B) {
1422  // min(min(a, b), min(c, a)) --> min(min(a, b), c)
1423  // min(min(a, b), min(c, b)) --> min(min(a, b), c)
1424  MinMaxOp = LHS;
1425  ThirdOp = C;
1426  } else if (C == A || C == B) {
1427  // min(min(a, b), min(b, d)) --> min(min(a, b), d)
1428  // min(min(a, b), min(c, b)) --> min(min(a, b), d)
1429  MinMaxOp = LHS;
1430  ThirdOp = D;
1431  }
1432  }
1433  if (!MinMaxOp || !ThirdOp)
1434  return nullptr;
1435 
1437  Value *CmpABC = Builder.CreateICmp(P, MinMaxOp, ThirdOp);
1438  return SelectInst::Create(CmpABC, MinMaxOp, ThirdOp);
1439 }
1440 
1442  Value *CondVal = SI.getCondition();
1443  Value *TrueVal = SI.getTrueValue();
1444  Value *FalseVal = SI.getFalseValue();
1445  Type *SelType = SI.getType();
1446 
1447  // FIXME: Remove this workaround when freeze related patches are done.
1448  // For select with undef operand which feeds into an equality comparison,
1449  // don't simplify it so loop unswitch can know the equality comparison
1450  // may have an undef operand. This is a workaround for PR31652 caused by
1451  // descrepancy about branch on undef between LoopUnswitch and GVN.
1452  if (isa<UndefValue>(TrueVal) || isa<UndefValue>(FalseVal)) {
1453  if (llvm::any_of(SI.users(), [&](User *U) {
1454  ICmpInst *CI = dyn_cast<ICmpInst>(U);
1455  if (CI && CI->isEquality())
1456  return true;
1457  return false;
1458  })) {
1459  return nullptr;
1460  }
1461  }
1462 
1463  if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal,
1464  SQ.getWithInstruction(&SI)))
1465  return replaceInstUsesWith(SI, V);
1466 
1467  if (Instruction *I = canonicalizeSelectToShuffle(SI))
1468  return I;
1469 
1470  // Canonicalize a one-use integer compare with a non-canonical predicate by
1471  // inverting the predicate and swapping the select operands. This matches a
1472  // compare canonicalization for conditional branches.
1473  // TODO: Should we do the same for FP compares?
1474  CmpInst::Predicate Pred;
1475  if (match(CondVal, m_OneUse(m_ICmp(Pred, m_Value(), m_Value()))) &&
1476  !isCanonicalPredicate(Pred)) {
1477  // Swap true/false values and condition.
1478  CmpInst *Cond = cast<CmpInst>(CondVal);
1480  SI.setOperand(1, FalseVal);
1481  SI.setOperand(2, TrueVal);
1482  SI.swapProfMetadata();
1483  Worklist.Add(Cond);
1484  return &SI;
1485  }
1486 
1487  if (SelType->isIntOrIntVectorTy(1) &&
1488  TrueVal->getType() == CondVal->getType()) {
1489  if (match(TrueVal, m_One())) {
1490  // Change: A = select B, true, C --> A = or B, C
1491  return BinaryOperator::CreateOr(CondVal, FalseVal);
1492  }
1493  if (match(TrueVal, m_Zero())) {
1494  // Change: A = select B, false, C --> A = and !B, C
1495  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1496  return BinaryOperator::CreateAnd(NotCond, FalseVal);
1497  }
1498  if (match(FalseVal, m_Zero())) {
1499  // Change: A = select B, C, false --> A = and B, C
1500  return BinaryOperator::CreateAnd(CondVal, TrueVal);
1501  }
1502  if (match(FalseVal, m_One())) {
1503  // Change: A = select B, C, true --> A = or !B, C
1504  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1505  return BinaryOperator::CreateOr(NotCond, TrueVal);
1506  }
1507 
1508  // select a, a, b -> a | b
1509  // select a, b, a -> a & b
1510  if (CondVal == TrueVal)
1511  return BinaryOperator::CreateOr(CondVal, FalseVal);
1512  if (CondVal == FalseVal)
1513  return BinaryOperator::CreateAnd(CondVal, TrueVal);
1514 
1515  // select a, ~a, b -> (~a) & b
1516  // select a, b, ~a -> (~a) | b
1517  if (match(TrueVal, m_Not(m_Specific(CondVal))))
1518  return BinaryOperator::CreateAnd(TrueVal, FalseVal);
1519  if (match(FalseVal, m_Not(m_Specific(CondVal))))
1520  return BinaryOperator::CreateOr(TrueVal, FalseVal);
1521  }
1522 
1523  // Selecting between two integer or vector splat integer constants?
1524  //
1525  // Note that we don't handle a scalar select of vectors:
1526  // select i1 %c, <2 x i8> <1, 1>, <2 x i8> <0, 0>
1527  // because that may need 3 instructions to splat the condition value:
1528  // extend, insertelement, shufflevector.
1529  if (SelType->isIntOrIntVectorTy() &&
1530  CondVal->getType()->isVectorTy() == SelType->isVectorTy()) {
1531  // select C, 1, 0 -> zext C to int
1532  if (match(TrueVal, m_One()) && match(FalseVal, m_Zero()))
1533  return new ZExtInst(CondVal, SelType);
1534 
1535  // select C, -1, 0 -> sext C to int
1536  if (match(TrueVal, m_AllOnes()) && match(FalseVal, m_Zero()))
1537  return new SExtInst(CondVal, SelType);
1538 
1539  // select C, 0, 1 -> zext !C to int
1540  if (match(TrueVal, m_Zero()) && match(FalseVal, m_One())) {
1541  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1542  return new ZExtInst(NotCond, SelType);
1543  }
1544 
1545  // select C, 0, -1 -> sext !C to int
1546  if (match(TrueVal, m_Zero()) && match(FalseVal, m_AllOnes())) {
1547  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1548  return new SExtInst(NotCond, SelType);
1549  }
1550  }
1551 
1552  // See if we are selecting two values based on a comparison of the two values.
1553  if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
1554  if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
1555  // Transform (X == Y) ? X : Y -> Y
1556  if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
1557  // This is not safe in general for floating point:
1558  // consider X== -0, Y== +0.
1559  // It becomes safe if either operand is a nonzero constant.
1560  ConstantFP *CFPt, *CFPf;
1561  if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
1562  !CFPt->getValueAPF().isZero()) ||
1563  ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
1564  !CFPf->getValueAPF().isZero()))
1565  return replaceInstUsesWith(SI, FalseVal);
1566  }
1567  // Transform (X une Y) ? X : Y -> X
1568  if (FCI->getPredicate() == FCmpInst::FCMP_UNE) {
1569  // This is not safe in general for floating point:
1570  // consider X== -0, Y== +0.
1571  // It becomes safe if either operand is a nonzero constant.
1572  ConstantFP *CFPt, *CFPf;
1573  if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
1574  !CFPt->getValueAPF().isZero()) ||
1575  ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
1576  !CFPf->getValueAPF().isZero()))
1577  return replaceInstUsesWith(SI, TrueVal);
1578  }
1579 
1580  // Canonicalize to use ordered comparisons by swapping the select
1581  // operands.
1582  //
1583  // e.g.
1584  // (X ugt Y) ? X : Y -> (X ole Y) ? Y : X
1585  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
1586  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
1587  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1588  Builder.setFastMathFlags(FCI->getFastMathFlags());
1589  Value *NewCond = Builder.CreateFCmp(InvPred, TrueVal, FalseVal,
1590  FCI->getName() + ".inv");
1591 
1592  return SelectInst::Create(NewCond, FalseVal, TrueVal,
1593  SI.getName() + ".p");
1594  }
1595 
1596  // NOTE: if we wanted to, this is where to detect MIN/MAX
1597  } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
1598  // Transform (X == Y) ? Y : X -> X
1599  if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
1600  // This is not safe in general for floating point:
1601  // consider X== -0, Y== +0.
1602  // It becomes safe if either operand is a nonzero constant.
1603  ConstantFP *CFPt, *CFPf;
1604  if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
1605  !CFPt->getValueAPF().isZero()) ||
1606  ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
1607  !CFPf->getValueAPF().isZero()))
1608  return replaceInstUsesWith(SI, FalseVal);
1609  }
1610  // Transform (X une Y) ? Y : X -> Y
1611  if (FCI->getPredicate() == FCmpInst::FCMP_UNE) {
1612  // This is not safe in general for floating point:
1613  // consider X== -0, Y== +0.
1614  // It becomes safe if either operand is a nonzero constant.
1615  ConstantFP *CFPt, *CFPf;
1616  if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
1617  !CFPt->getValueAPF().isZero()) ||
1618  ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
1619  !CFPf->getValueAPF().isZero()))
1620  return replaceInstUsesWith(SI, TrueVal);
1621  }
1622 
1623  // Canonicalize to use ordered comparisons by swapping the select
1624  // operands.
1625  //
1626  // e.g.
1627  // (X ugt Y) ? X : Y -> (X ole Y) ? X : Y
1628  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
1629  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
1630  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1631  Builder.setFastMathFlags(FCI->getFastMathFlags());
1632  Value *NewCond = Builder.CreateFCmp(InvPred, FalseVal, TrueVal,
1633  FCI->getName() + ".inv");
1634 
1635  return SelectInst::Create(NewCond, FalseVal, TrueVal,
1636  SI.getName() + ".p");
1637  }
1638 
1639  // NOTE: if we wanted to, this is where to detect MIN/MAX
1640  }
1641 
1642  // Canonicalize select with fcmp to fabs(). -0.0 makes this tricky. We need
1643  // fast-math-flags (nsz) or fsub with +0.0 (not fneg) for this to work. We
1644  // also require nnan because we do not want to unintentionally change the
1645  // sign of a NaN value.
1646  Value *X = FCI->getOperand(0);
1647  FCmpInst::Predicate Pred = FCI->getPredicate();
1648  if (match(FCI->getOperand(1), m_AnyZeroFP()) && FCI->hasNoNaNs()) {
1649  // (X <= +/-0.0) ? (0.0 - X) : X --> fabs(X)
1650  // (X > +/-0.0) ? X : (0.0 - X) --> fabs(X)
1651  if ((X == FalseVal && Pred == FCmpInst::FCMP_OLE &&
1652  match(TrueVal, m_FSub(m_PosZeroFP(), m_Specific(X)))) ||
1653  (X == TrueVal && Pred == FCmpInst::FCMP_OGT &&
1654  match(FalseVal, m_FSub(m_PosZeroFP(), m_Specific(X))))) {
1655  Value *Fabs = Builder.CreateIntrinsic(Intrinsic::fabs, { X }, FCI);
1656  return replaceInstUsesWith(SI, Fabs);
1657  }
1658  // With nsz:
1659  // (X < +/-0.0) ? -X : X --> fabs(X)
1660  // (X <= +/-0.0) ? -X : X --> fabs(X)
1661  // (X > +/-0.0) ? X : -X --> fabs(X)
1662  // (X >= +/-0.0) ? X : -X --> fabs(X)
1663  if (FCI->hasNoSignedZeros() &&
1664  ((X == FalseVal && match(TrueVal, m_FNeg(m_Specific(X))) &&
1665  (Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_OLE)) ||
1666  (X == TrueVal && match(FalseVal, m_FNeg(m_Specific(X))) &&
1667  (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_OGE)))) {
1668  Value *Fabs = Builder.CreateIntrinsic(Intrinsic::fabs, { X }, FCI);
1669  return replaceInstUsesWith(SI, Fabs);
1670  }
1671  }
1672  }
1673 
1674  // See if we are selecting two values based on a comparison of the two values.
1675  if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
1676  if (Instruction *Result = foldSelectInstWithICmp(SI, ICI))
1677  return Result;
1678 
1679  if (Instruction *Add = foldAddSubSelect(SI, Builder))
1680  return Add;
1681 
1682  // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
1683  auto *TI = dyn_cast<Instruction>(TrueVal);
1684  auto *FI = dyn_cast<Instruction>(FalseVal);
1685  if (TI && FI && TI->getOpcode() == FI->getOpcode())
1686  if (Instruction *IV = foldSelectOpOp(SI, TI, FI))
1687  return IV;
1688 
1689  if (Instruction *I = foldSelectExtConst(SI))
1690  return I;
1691 
1692  // See if we can fold the select into one of our operands.
1693  if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) {
1694  if (Instruction *FoldI = foldSelectIntoOp(SI, TrueVal, FalseVal))
1695  return FoldI;
1696 
1697  Value *LHS, *RHS, *LHS2, *RHS2;
1698  Instruction::CastOps CastOp;
1699  SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp);
1700  auto SPF = SPR.Flavor;
1701 
1703  // Canonicalize so that
1704  // - type casts are outside select patterns.
1705  // - float clamp is transformed to min/max pattern
1706 
1707  bool IsCastNeeded = LHS->getType() != SelType;
1708  Value *CmpLHS = cast<CmpInst>(CondVal)->getOperand(0);
1709  Value *CmpRHS = cast<CmpInst>(CondVal)->getOperand(1);
1710  if (IsCastNeeded ||
1711  (LHS->getType()->isFPOrFPVectorTy() &&
1712  ((CmpLHS != LHS && CmpLHS != RHS) ||
1713  (CmpRHS != LHS && CmpRHS != RHS)))) {
1714  CmpInst::Predicate Pred = getMinMaxPred(SPF, SPR.Ordered);
1715 
1716  Value *Cmp;
1717  if (CmpInst::isIntPredicate(Pred)) {
1718  Cmp = Builder.CreateICmp(Pred, LHS, RHS);
1719  } else {
1720  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1721  auto FMF = cast<FPMathOperator>(SI.getCondition())->getFastMathFlags();
1722  Builder.setFastMathFlags(FMF);
1723  Cmp = Builder.CreateFCmp(Pred, LHS, RHS);
1724  }
1725 
1726  Value *NewSI = Builder.CreateSelect(Cmp, LHS, RHS, SI.getName(), &SI);
1727  if (!IsCastNeeded)
1728  return replaceInstUsesWith(SI, NewSI);
1729 
1730  Value *NewCast = Builder.CreateCast(CastOp, NewSI, SelType);
1731  return replaceInstUsesWith(SI, NewCast);
1732  }
1733 
1734  // MAX(~a, ~b) -> ~MIN(a, b)
1735  // MIN(~a, ~b) -> ~MAX(a, b)
1736  Value *A, *B;
1737  if (match(LHS, m_Not(m_Value(A))) && match(RHS, m_Not(m_Value(B))) &&
1738  (LHS->getNumUses() <= 2 || RHS->getNumUses() <= 2)) {
1739  CmpInst::Predicate InvertedPred = getInverseMinMaxPred(SPF);
1740  Value *InvertedCmp = Builder.CreateICmp(InvertedPred, A, B);
1741  Value *NewSel = Builder.CreateSelect(InvertedCmp, A, B);
1742  return BinaryOperator::CreateNot(NewSel);
1743  }
1744 
1745  if (Instruction *I = factorizeMinMaxTree(SPF, LHS, RHS, Builder))
1746  return I;
1747  }
1748 
1749  if (SPF) {
1750  // MAX(MAX(a, b), a) -> MAX(a, b)
1751  // MIN(MIN(a, b), a) -> MIN(a, b)
1752  // MAX(MIN(a, b), a) -> a
1753  // MIN(MAX(a, b), a) -> a
1754  // ABS(ABS(a)) -> ABS(a)
1755  // NABS(NABS(a)) -> NABS(a)
1756  if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor)
1757  if (Instruction *R = foldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
1758  SI, SPF, RHS))
1759  return R;
1760  if (SelectPatternFlavor SPF2 = matchSelectPattern(RHS, LHS2, RHS2).Flavor)
1761  if (Instruction *R = foldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2,
1762  SI, SPF, LHS))
1763  return R;
1764  }
1765 
1766  // TODO.
1767  // ABS(-X) -> ABS(X)
1768  }
1769 
1770  // See if we can fold the select into a phi node if the condition is a select.
1771  if (auto *PN = dyn_cast<PHINode>(SI.getCondition()))
1772  // The true/false values have to be live in the PHI predecessor's blocks.
1773  if (canSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
1774  canSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
1775  if (Instruction *NV = foldOpIntoPhi(SI, PN))
1776  return NV;
1777 
1778  if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
1779  if (TrueSI->getCondition()->getType() == CondVal->getType()) {
1780  // select(C, select(C, a, b), c) -> select(C, a, c)
1781  if (TrueSI->getCondition() == CondVal) {
1782  if (SI.getTrueValue() == TrueSI->getTrueValue())
1783  return nullptr;
1784  SI.setOperand(1, TrueSI->getTrueValue());
1785  return &SI;
1786  }
1787  // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
1788  // We choose this as normal form to enable folding on the And and shortening
1789  // paths for the values (this helps GetUnderlyingObjects() for example).
1790  if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
1791  Value *And = Builder.CreateAnd(CondVal, TrueSI->getCondition());
1792  SI.setOperand(0, And);
1793  SI.setOperand(1, TrueSI->getTrueValue());
1794  return &SI;
1795  }
1796  }
1797  }
1798  if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
1799  if (FalseSI->getCondition()->getType() == CondVal->getType()) {
1800  // select(C, a, select(C, b, c)) -> select(C, a, c)
1801  if (FalseSI->getCondition() == CondVal) {
1802  if (SI.getFalseValue() == FalseSI->getFalseValue())
1803  return nullptr;
1804  SI.setOperand(2, FalseSI->getFalseValue());
1805  return &SI;
1806  }
1807  // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
1808  if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
1809  Value *Or = Builder.CreateOr(CondVal, FalseSI->getCondition());
1810  SI.setOperand(0, Or);
1811  SI.setOperand(2, FalseSI->getFalseValue());
1812  return &SI;
1813  }
1814  }
1815  }
1816 
1817  auto canMergeSelectThroughBinop = [](BinaryOperator *BO) {
1818  // The select might be preventing a division by 0.
1819  switch (BO->getOpcode()) {
1820  default:
1821  return true;
1822  case Instruction::SRem:
1823  case Instruction::URem:
1824  case Instruction::SDiv:
1825  case Instruction::UDiv:
1826  return false;
1827  }
1828  };
1829 
1830  // Try to simplify a binop sandwiched between 2 selects with the same
1831  // condition.
1832  // select(C, binop(select(C, X, Y), W), Z) -> select(C, binop(X, W), Z)
1833  BinaryOperator *TrueBO;
1834  if (match(TrueVal, m_OneUse(m_BinOp(TrueBO))) &&
1835  canMergeSelectThroughBinop(TrueBO)) {
1836  if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(0))) {
1837  if (TrueBOSI->getCondition() == CondVal) {
1838  TrueBO->setOperand(0, TrueBOSI->getTrueValue());
1839  Worklist.Add(TrueBO);
1840  return &SI;
1841  }
1842  }
1843  if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(1))) {
1844  if (TrueBOSI->getCondition() == CondVal) {
1845  TrueBO->setOperand(1, TrueBOSI->getTrueValue());
1846  Worklist.Add(TrueBO);
1847  return &SI;
1848  }
1849  }
1850  }
1851 
1852  // select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W))
1853  BinaryOperator *FalseBO;
1854  if (match(FalseVal, m_OneUse(m_BinOp(FalseBO))) &&
1855  canMergeSelectThroughBinop(FalseBO)) {
1856  if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(0))) {
1857  if (FalseBOSI->getCondition() == CondVal) {
1858  FalseBO->setOperand(0, FalseBOSI->getFalseValue());
1859  Worklist.Add(FalseBO);
1860  return &SI;
1861  }
1862  }
1863  if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(1))) {
1864  if (FalseBOSI->getCondition() == CondVal) {
1865  FalseBO->setOperand(1, FalseBOSI->getFalseValue());
1866  Worklist.Add(FalseBO);
1867  return &SI;
1868  }
1869  }
1870  }
1871 
1872  if (BinaryOperator::isNot(CondVal)) {
1874  SI.setOperand(1, FalseVal);
1875  SI.setOperand(2, TrueVal);
1876  return &SI;
1877  }
1878 
1879  if (VectorType *VecTy = dyn_cast<VectorType>(SelType)) {
1880  unsigned VWidth = VecTy->getNumElements();
1881  APInt UndefElts(VWidth, 0);
1882  APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
1883  if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) {
1884  if (V != &SI)
1885  return replaceInstUsesWith(SI, V);
1886  return &SI;
1887  }
1888  }
1889 
1890  // See if we can determine the result of this select based on a dominating
1891  // condition.
1892  BasicBlock *Parent = SI.getParent();
1893  if (BasicBlock *Dom = Parent->getSinglePredecessor()) {
1894  auto *PBI = dyn_cast_or_null<BranchInst>(Dom->getTerminator());
1895  if (PBI && PBI->isConditional() &&
1896  PBI->getSuccessor(0) != PBI->getSuccessor(1) &&
1897  (PBI->getSuccessor(0) == Parent || PBI->getSuccessor(1) == Parent)) {
1898  bool CondIsTrue = PBI->getSuccessor(0) == Parent;
1899  Optional<bool> Implication = isImpliedCondition(
1900  PBI->getCondition(), SI.getCondition(), DL, CondIsTrue);
1901  if (Implication) {
1902  Value *V = *Implication ? TrueVal : FalseVal;
1903  return replaceInstUsesWith(SI, V);
1904  }
1905  }
1906  }
1907 
1908  // If we can compute the condition, there's no need for a select.
1909  // Like the above fold, we are attempting to reduce compile-time cost by
1910  // putting this fold here with limitations rather than in InstSimplify.
1911  // The motivation for this call into value tracking is to take advantage of
1912  // the assumption cache, so make sure that is populated.
1913  if (!CondVal->getType()->isVectorTy() && !AC.assumptions().empty()) {
1914  KnownBits Known(1);
1915  computeKnownBits(CondVal, Known, 0, &SI);
1916  if (Known.One.isOneValue())
1917  return replaceInstUsesWith(SI, TrueVal);
1918  if (Known.Zero.isOneValue())
1919  return replaceInstUsesWith(SI, FalseVal);
1920  }
1921 
1922  if (Instruction *BitCastSel = foldSelectCmpBitcasts(SI, Builder))
1923  return BitCastSel;
1924 
1925  // Simplify selects that test the returned flag of cmpxchg instructions.
1926  if (Instruction *Select = foldSelectCmpXchg(SI))
1927  return Select;
1928 
1929  return nullptr;
1930 }
MaxMin_match< ICmpInst, LHS, RHS, umin_pred_ty > m_UMin(const LHS &L, const RHS &R)
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:709
uint64_t CallInst * C
BinaryOp_match< cstfp_pred_ty< is_neg_zero_fp >, RHS, Instruction::FSub > m_FNeg(const RHS &X)
Match &#39;fneg X&#39; as &#39;fsub -0.0, X&#39;.
Definition: PatternMatch.h:656
static bool isSelect01(const APInt &C1I, const APInt &C2I)
static ConstantInt * getFalse(LLVMContext &Context)
Definition: Constants.cpp:574
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:72
Value * CreateICmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1846
This class is the base class for the comparison instructions.
Definition: InstrTypes.h:875
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 isZero() const
Definition: APFloat.h:1143
static bool IsFreeToInvert(Value *V, bool WillInvertAllUses)
Return true if the specified value is free to invert (apply ~ to).
class_match< CmpInst > m_Cmp()
Matches any compare instruction and ignore it.
Definition: PatternMatch.h:80
This instruction extracts a struct member or array element value from an aggregate value...
static APInt getAllOnesValue(unsigned numBits)
Get the all-ones value.
Definition: APInt.h:555
BinaryOp_match< LHS, RHS, Instruction::Sub > m_Sub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:642
is_zero m_Zero()
Match any null constant or a vector with all elements equal to 0.
Definition: PatternMatch.h:373
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:1996
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:1566
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
BinaryOps getOpcode() const
Definition: InstrTypes.h:555
Value * CreateXor(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1148
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:514
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:863
bool slt(const APInt &RHS) const
Signed less than comparison.
Definition: APInt.h:1188
class_match< Constant > m_Constant()
Match an arbitrary Constant and ignore it.
Definition: PatternMatch.h:91
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:911
unsigned less than
Definition: InstrTypes.h:910
0 1 0 0 True if ordered and less than
Definition: InstrTypes.h:891
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:713
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:901
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:1258
static bool isEquality(Predicate P)
Return true if this predicate is either EQ or NE.
SelectPatternFlavor getInverseMinMaxFlavor(SelectPatternFlavor SPF)
Return the inverse minimum/maximum flavor of the specified flavor.
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:648
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:227
void reserve(size_type N)
Definition: SmallVector.h:377
bool sle(const APInt &RHS) const
Signed less or equal comparison.
Definition: APInt.h:1223
void copyIRFlags(const Value *V, bool IncludeWrapFlags=true)
Convenience method to copy supported exact, fast-math, and (optionally) wrapping flags from V to this...
cst_pred_ty< is_zero_int > m_ZeroInt()
Match an integer 0 or a vector with all elements equal to 0.
Definition: PatternMatch.h:361
bool Ordered
Only applicable if Flavor is SPF_FMINNUM or SPF_FMAXNUM.
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1493
Signed maximum.
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:258
Value * CreateNot(Value *V, const Twine &Name="")
Definition: IRBuilder.h:1282
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
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:721
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:983
Absolute value.
bool isUnsigned() const
Definition: InstrTypes.h:1060
CastClass_match< OpTy, Instruction::Trunc > m_Trunc(const OpTy &Op)
Matches Trunc.
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:731
0 1 0 1 True if ordered and less than or equal
Definition: InstrTypes.h:892
static Constant * getSExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1618
This file implements a class to represent arbitrary precision integral constant values and operations...
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1632
Instruction * clone() const
Create a copy of &#39;this&#39; instruction that is identical in all ways except the following: ...
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:245
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.
MaxMin_match< ICmpInst, LHS, RHS, smin_pred_ty > m_SMin(const LHS &L, const RHS &R)
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:126
cstfp_pred_ty< is_pos_zero_fp > m_PosZeroFP()
Match a floating-point positive zero.
Definition: PatternMatch.h:433
Value * CreateSub(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:979
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:203
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:382
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:301
static BinaryOperator * CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
static const Value * getNotArgument(const Value *BinOp)
Value * getOperand(unsigned i) const
Definition: User.h:170
void replaceUsesOfWith(Value *From, Value *To)
Replace uses of one Value with another.
Definition: User.cpp:21
Value * CreateOr(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1130
Constant * getAggregateElement(unsigned Elt) const
For aggregates (struct/array/vector) return the constant that corresponds to the specified element if...
Definition: Constants.cpp:328
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:301
Value * CreateFCmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1854
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:63
#define P(N)
BinaryOp_match< LHS, RHS, Instruction::LShr > m_LShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:733
bool hasNUsesOrMore(unsigned N) const
Return true if this value has N users or more.
Definition: Value.cpp:140
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:389
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)
apint_match m_APInt(const APInt *&Res)
Match a ConstantInt or splatted ConstantVector, binding the specified pointer to the contained APInt...
Definition: PatternMatch.h:177
const BasicBlock * getSinglePredecessor() const
Return the predecessor of this block if it has a single predecessor block.
Definition: BasicBlock.cpp:235
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
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:715
CallInst * CreateIntrinsic(Intrinsic::ID ID, Instruction *FMFSource=nullptr, const Twine &Name="")
Create a call to intrinsic ID with no operands.
Definition: IRBuilder.cpp:741
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1169
CastClass_match< OpTy, Instruction::BitCast > m_BitCast(const OpTy &Op)
Matches BitCast.
This is an important base class in LLVM.
Definition: Constant.h:42
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:1901
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.
ConstantFP - Floating Point Values [float, double].
Definition: Constants.h:264
bool isOneValue() const
Determine if this is a value of 1.
Definition: APInt.h:404
cst_pred_ty< is_all_ones > m_AllOnes()
Match an integer or vector with all bits set.
Definition: PatternMatch.h:306
static APInt getOneBitSet(unsigned numBits, unsigned BitNo)
Return an APInt with exactly one bit set in the result.
Definition: APInt.h:581
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:490
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:915
Value * CreateNeg(Value *V, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1256
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:885
void setArgOperand(unsigned i, Value *v)
CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF, bool Ordered=false)
Return the canonical comparison predicate for the specified minimum/maximum flavor.
static bool isNot(const Value *V)
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:75
Class to represent integer types.
Definition: DerivedTypes.h:40
CmpInst::Predicate getInverseMinMaxPred(SelectPatternFlavor SPF)
Return the canonical inverse comparison predicate for the specified minimum/maximum flavor...
const Value * getCondition() const
bool isCast() const
Definition: Instruction.h:132
void swapProfMetadata()
If the instruction has "branch_weights" MD_prof metadata and the MDNode has three operands (including...
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
signed greater than
Definition: InstrTypes.h:912
neg_match< LHS > m_Neg(const LHS &L)
Match an integer negate.
const APFloat & getValueAPF() const
Definition: Constants.h:299
CastClass_match< OpTy, Instruction::SExt > m_SExt(const OpTy &Op)
Matches SExt.
Floating point maxnum.
static Value * createMinMax(InstCombiner::BuilderTy &Builder, SelectPatternFlavor SPF, Value *A, Value *B)
0 0 1 0 True if ordered and greater than
Definition: InstrTypes.h:889
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:192
SelectPatternFlavor Flavor
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type...
Definition: Type.cpp:130
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
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:64
signed less than
Definition: InstrTypes.h:914
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:1604
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:611
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1277
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:567
bool isCommutative() const
Return true if the instruction is commutative:
Definition: Instruction.h:452
Instruction * visitSelectInst(SelectInst &SI)
void setPredicate(Predicate P)
Set the predicate for this instruction to the specified value.
Definition: InstrTypes.h:964
void setOperand(unsigned i, Value *Val)
Definition: User.h:175
unsigned logBase2() const
Definition: APInt.h:1732
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:924
unsigned getVectorNumElements() const
Definition: DerivedTypes.h:462
bool isIntPredicate() const
Definition: InstrTypes.h:977
Class to represent vector types.
Definition: DerivedTypes.h:393
Class for arbitrary precision integers.
Definition: APInt.h:69
bool ule(const APInt &RHS) const
Unsigned less or equal comparison.
Definition: APInt.h:1207
bool isPowerOf2() const
Check if this APInt&#39;s value is a power of two greater than zero.
Definition: APInt.h:457
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:1293
iterator_range< user_iterator > users()
Definition: Value.h:399
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1497
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1051
const Value * getFalseValue() const
void setCondition(Value *V)
static APInt getSelectFoldableConstant(BinaryOperator *I)
For the same transformation as the previous function, return the identity constant that goes into the...
static CastInst * Create(Instruction::CastOps, Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Provides a way to construct any of the CastInst subclasses using an opcode instead of the subclass&#39;s ...
bool ugt(const APInt &RHS) const
Unsigned greather than comparison.
Definition: APInt.h:1239
Predicate getPredicate() const
Return the predicate for this instruction.
Definition: InstrTypes.h:959
unsigned getNumUses() const
This method computes the number of uses of this Value.
Definition: Value.cpp:170
static cl::opt< bool > NeedAnd("extract-needand", cl::init(true), cl::Hidden, cl::desc("Require & in extract patterns"))
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: ((a > b) ? a : b) - b) This produces a canonica...
void setTrueValue(Value *V)
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:176
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:909
static bool isUnordered(Predicate predicate)
Determine if the predicate is an unordered operation.
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:224
bool isEquality() const
Return true if this predicate is either EQ or NE.
#define I(x, y, z)
Definition: MD5.cpp:58
MaxMin_match< ICmpInst, LHS, RHS, smax_pred_ty > m_SMax(const LHS &L, const RHS &R)
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:323
void setFalseValue(Value *V)
Signed minimum.
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1112
Optional< bool > isImpliedCondition(const Value *LHS, const Value *RHS, const DataLayout &DL, bool LHSIsTrue=true, unsigned Depth=0)
Return true if RHS is known to be implied true by LHS.
InstTy * Insert(InstTy *I, const Twine &Name="") const
Insert and return the specified instruction.
Definition: IRBuilder.h:782
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:1666
static GetElementPtrInst * CreateInBounds(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Create an "inbounds" getelementptr.
Definition: Instructions.h:897
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:538
0 0 0 1 True if ordered and equal
Definition: InstrTypes.h:888
LLVM Value Representation.
Definition: Value.h:73
This file provides internal interfaces used to implement the InstCombine.
SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, Instruction::CastOps *CastOp=nullptr, unsigned Depth=0)
Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind and providing the out param...
cst_pred_ty< is_one > m_One()
Match an integer 1 or a vector with all elements equal to 1.
Definition: PatternMatch.h:352
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:81
void setFastMathFlags(FastMathFlags NewFMF)
Set the fast-math flags to be used with generated fp-math operators.
Definition: IRBuilder.h:220
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:1072
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:412
Convenience struct for specifying and reasoning about fast-math flags.
Definition: Operator.h:160
unsigned greater than
Definition: InstrTypes.h:908
Predicate getSwappedPredicate() const
For example, EQ->EQ, SLE->SGE, ULT->UGT, OEQ->OEQ, ULE->UGE, OLT->OGT, etc.
Definition: InstrTypes.h:999
static APInt getNullValue(unsigned numBits)
Get the &#39;0&#39; value.
Definition: APInt.h:562
specific_intval m_SpecificInt(uint64_t V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:567
cstfp_pred_ty< is_any_zero_fp > m_AnyZeroFP()
Match a floating-point negative zero or positive zero.
Definition: PatternMatch.h:424
0 0 1 1 True if ordered and greater than or equal
Definition: InstrTypes.h:890
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)
Determine which bits of V are known to be either zero or one and return them in the KnownZero/KnownOn...
static Constant * get(ArrayRef< Constant *> V)
Definition: Constants.cpp:1046
Value * CreateFNeg(Value *V, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1274
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:467
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:399
IntegerType * Int32Ty
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:44
const BasicBlock * getParent() const
Definition: Instruction.h:67
CmpClass_match< LHS, RHS, ICmpInst, ICmpInst::Predicate > m_ICmp(ICmpInst::Predicate &Pred, const LHS &L, const RHS &R)
Definition: PatternMatch.h:974