LLVM  6.0.0svn
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"
18 #include "llvm/IR/MDBuilder.h"
19 #include "llvm/IR/PatternMatch.h"
20 #include "llvm/Support/KnownBits.h"
21 using namespace llvm;
22 using namespace PatternMatch;
23 
24 #define DEBUG_TYPE "instcombine"
25 
28  switch (SPF) {
29  default:
30  llvm_unreachable("unhandled!");
31 
32  case SPF_SMIN:
33  return SPF_SMAX;
34  case SPF_UMIN:
35  return SPF_UMAX;
36  case SPF_SMAX:
37  return SPF_SMIN;
38  case SPF_UMAX:
39  return SPF_UMIN;
40  }
41 }
42 
44  bool Ordered=false) {
45  switch (SPF) {
46  default:
47  llvm_unreachable("unhandled!");
48 
49  case SPF_SMIN:
50  return ICmpInst::ICMP_SLT;
51  case SPF_UMIN:
52  return ICmpInst::ICMP_ULT;
53  case SPF_SMAX:
54  return ICmpInst::ICMP_SGT;
55  case SPF_UMAX:
56  return ICmpInst::ICMP_UGT;
57  case SPF_FMINNUM:
58  return Ordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT;
59  case SPF_FMAXNUM:
60  return Ordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT;
61  }
62 }
63 
66  Value *B) {
69  return Builder.CreateSelect(Builder.CreateICmp(Pred, A, B), A, B);
70 }
71 
72 /// We want to turn code that looks like this:
73 /// %C = or %A, %B
74 /// %D = select %cond, %C, %A
75 /// into:
76 /// %C = select %cond, %B, 0
77 /// %D = or %A, %C
78 ///
79 /// Assuming that the specified instruction is an operand to the select, return
80 /// a bitmask indicating which operands of this instruction are foldable if they
81 /// equal the other incoming value of the select.
82 ///
84  switch (I->getOpcode()) {
85  case Instruction::Add:
86  case Instruction::Mul:
87  case Instruction::And:
88  case Instruction::Or:
89  case Instruction::Xor:
90  return 3; // Can fold through either operand.
91  case Instruction::Sub: // Can only fold on the amount subtracted.
92  case Instruction::Shl: // Can only fold on the shift amount.
93  case Instruction::LShr:
94  case Instruction::AShr:
95  return 1;
96  default:
97  return 0; // Cannot fold
98  }
99 }
100 
101 /// For the same transformation as the previous function, return the identity
102 /// constant that goes into the select.
104  switch (I->getOpcode()) {
105  default: llvm_unreachable("This cannot happen!");
106  case Instruction::Add:
107  case Instruction::Sub:
108  case Instruction::Or:
109  case Instruction::Xor:
110  case Instruction::Shl:
111  case Instruction::LShr:
112  case Instruction::AShr:
113  return Constant::getNullValue(I->getType());
114  case Instruction::And:
115  return Constant::getAllOnesValue(I->getType());
116  case Instruction::Mul:
117  return ConstantInt::get(I->getType(), 1);
118  }
119 }
120 
121 /// We have (select c, TI, FI), and we know that TI and FI have the same opcode.
122 Instruction *InstCombiner::foldSelectOpOp(SelectInst &SI, Instruction *TI,
123  Instruction *FI) {
124  // Don't break up min/max patterns. The hasOneUse checks below prevent that
125  // for most cases, but vector min/max with bitcasts can be transformed. If the
126  // one-use restrictions are eased for other patterns, we still don't want to
127  // obfuscate min/max.
128  if ((match(&SI, m_SMin(m_Value(), m_Value())) ||
129  match(&SI, m_SMax(m_Value(), m_Value())) ||
130  match(&SI, m_UMin(m_Value(), m_Value())) ||
131  match(&SI, m_UMax(m_Value(), m_Value()))))
132  return nullptr;
133 
134  // If this is a cast from the same type, merge.
135  if (TI->getNumOperands() == 1 && TI->isCast()) {
136  Type *FIOpndTy = FI->getOperand(0)->getType();
137  if (TI->getOperand(0)->getType() != FIOpndTy)
138  return nullptr;
139 
140  // The select condition may be a vector. We may only change the operand
141  // type if the vector width remains the same (and matches the condition).
142  Type *CondTy = SI.getCondition()->getType();
143  if (CondTy->isVectorTy()) {
144  if (!FIOpndTy->isVectorTy())
145  return nullptr;
146  if (CondTy->getVectorNumElements() != FIOpndTy->getVectorNumElements())
147  return nullptr;
148 
149  // TODO: If the backend knew how to deal with casts better, we could
150  // remove this limitation. For now, there's too much potential to create
151  // worse codegen by promoting the select ahead of size-altering casts
152  // (PR28160).
153  //
154  // Note that ValueTracking's matchSelectPattern() looks through casts
155  // without checking 'hasOneUse' when it matches min/max patterns, so this
156  // transform may end up happening anyway.
157  if (TI->getOpcode() != Instruction::BitCast &&
158  (!TI->hasOneUse() || !FI->hasOneUse()))
159  return nullptr;
160 
161  } else if (!TI->hasOneUse() || !FI->hasOneUse()) {
162  // TODO: The one-use restrictions for a scalar select could be eased if
163  // the fold of a select in visitLoadInst() was enhanced to match a pattern
164  // that includes a cast.
165  return nullptr;
166  }
167 
168  // Fold this by inserting a select from the input values.
169  Value *NewSI =
170  Builder.CreateSelect(SI.getCondition(), TI->getOperand(0),
171  FI->getOperand(0), SI.getName() + ".v", &SI);
172  return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
173  TI->getType());
174  }
175 
176  // Only handle binary operators with one-use here. As with the cast case
177  // above, it may be possible to relax the one-use constraint, but that needs
178  // be examined carefully since it may not reduce the total number of
179  // instructions.
181  if (!BO || !TI->hasOneUse() || !FI->hasOneUse())
182  return nullptr;
183 
184  // Figure out if the operations have any operands in common.
185  Value *MatchOp, *OtherOpT, *OtherOpF;
186  bool MatchIsOpZero;
187  if (TI->getOperand(0) == FI->getOperand(0)) {
188  MatchOp = TI->getOperand(0);
189  OtherOpT = TI->getOperand(1);
190  OtherOpF = FI->getOperand(1);
191  MatchIsOpZero = true;
192  } else if (TI->getOperand(1) == FI->getOperand(1)) {
193  MatchOp = TI->getOperand(1);
194  OtherOpT = TI->getOperand(0);
195  OtherOpF = FI->getOperand(0);
196  MatchIsOpZero = false;
197  } else if (!TI->isCommutative()) {
198  return nullptr;
199  } else if (TI->getOperand(0) == FI->getOperand(1)) {
200  MatchOp = TI->getOperand(0);
201  OtherOpT = TI->getOperand(1);
202  OtherOpF = FI->getOperand(0);
203  MatchIsOpZero = true;
204  } else if (TI->getOperand(1) == FI->getOperand(0)) {
205  MatchOp = TI->getOperand(1);
206  OtherOpT = TI->getOperand(0);
207  OtherOpF = FI->getOperand(1);
208  MatchIsOpZero = true;
209  } else {
210  return nullptr;
211  }
212 
213  // If we reach here, they do have operations in common.
214  Value *NewSI = Builder.CreateSelect(SI.getCondition(), OtherOpT, OtherOpF,
215  SI.getName() + ".v", &SI);
216  Value *Op0 = MatchIsOpZero ? MatchOp : NewSI;
217  Value *Op1 = MatchIsOpZero ? NewSI : MatchOp;
218  return BinaryOperator::Create(BO->getOpcode(), Op0, Op1);
219 }
220 
221 static bool isSelect01(Constant *C1, Constant *C2) {
222  ConstantInt *C1I = dyn_cast<ConstantInt>(C1);
223  if (!C1I)
224  return false;
225  ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
226  if (!C2I)
227  return false;
228  if (!C1I->isZero() && !C2I->isZero()) // One side must be zero.
229  return false;
230  return C1I->isOne() || C1I->isMinusOne() ||
231  C2I->isOne() || C2I->isMinusOne();
232 }
233 
234 /// Try to fold the select into one of the operands to allow further
235 /// optimization.
236 Instruction *InstCombiner::foldSelectIntoOp(SelectInst &SI, Value *TrueVal,
237  Value *FalseVal) {
238  // See the comment above GetSelectFoldableOperands for a description of the
239  // transformation we are doing here.
240  if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
241  if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
242  !isa<Constant>(FalseVal)) {
243  if (unsigned SFO = getSelectFoldableOperands(TVI)) {
244  unsigned OpToFold = 0;
245  if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
246  OpToFold = 1;
247  } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
248  OpToFold = 2;
249  }
250 
251  if (OpToFold) {
253  Value *OOp = TVI->getOperand(2-OpToFold);
254  // Avoid creating select between 2 constants unless it's selecting
255  // between 0, 1 and -1.
256  if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
257  Value *NewSel = Builder.CreateSelect(SI.getCondition(), OOp, C);
258  NewSel->takeName(TVI);
259  BinaryOperator *TVI_BO = cast<BinaryOperator>(TVI);
261  FalseVal, NewSel);
262  BO->copyIRFlags(TVI_BO);
263  return BO;
264  }
265  }
266  }
267  }
268  }
269 
270  if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
271  if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
272  !isa<Constant>(TrueVal)) {
273  if (unsigned SFO = getSelectFoldableOperands(FVI)) {
274  unsigned OpToFold = 0;
275  if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
276  OpToFold = 1;
277  } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
278  OpToFold = 2;
279  }
280 
281  if (OpToFold) {
283  Value *OOp = FVI->getOperand(2-OpToFold);
284  // Avoid creating select between 2 constants unless it's selecting
285  // between 0, 1 and -1.
286  if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
287  Value *NewSel = Builder.CreateSelect(SI.getCondition(), C, OOp);
288  NewSel->takeName(FVI);
289  BinaryOperator *FVI_BO = cast<BinaryOperator>(FVI);
291  TrueVal, NewSel);
292  BO->copyIRFlags(FVI_BO);
293  return BO;
294  }
295  }
296  }
297  }
298  }
299 
300  return nullptr;
301 }
302 
303 /// We want to turn:
304 /// (select (icmp eq (and X, C1), 0), Y, (or Y, C2))
305 /// into:
306 /// (or (shl (and X, C1), C3), Y)
307 /// iff:
308 /// C1 and C2 are both powers of 2
309 /// where:
310 /// C3 = Log(C2) - Log(C1)
311 ///
312 /// This transform handles cases where:
313 /// 1. The icmp predicate is inverted
314 /// 2. The select operands are reversed
315 /// 3. The magnitude of C2 and C1 are flipped
316 static Value *foldSelectICmpAndOr(const SelectInst &SI, Value *TrueVal,
317  Value *FalseVal,
318  InstCombiner::BuilderTy &Builder) {
319  const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition());
320  if (!IC || !SI.getType()->isIntegerTy())
321  return nullptr;
322 
323  Value *CmpLHS = IC->getOperand(0);
324  Value *CmpRHS = IC->getOperand(1);
325 
326  Value *V;
327  unsigned C1Log;
328  bool IsEqualZero;
329  bool NeedAnd = false;
330  if (IC->isEquality()) {
331  if (!match(CmpRHS, m_Zero()))
332  return nullptr;
333 
334  const APInt *C1;
335  if (!match(CmpLHS, m_And(m_Value(), m_Power2(C1))))
336  return nullptr;
337 
338  V = CmpLHS;
339  C1Log = C1->logBase2();
340  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ;
341  } else if (IC->getPredicate() == ICmpInst::ICMP_SLT ||
342  IC->getPredicate() == ICmpInst::ICMP_SGT) {
343  // We also need to recognize (icmp slt (trunc (X)), 0) and
344  // (icmp sgt (trunc (X)), -1).
345  IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_SGT;
346  if ((IsEqualZero && !match(CmpRHS, m_AllOnes())) ||
347  (!IsEqualZero && !match(CmpRHS, m_Zero())))
348  return nullptr;
349 
350  if (!match(CmpLHS, m_OneUse(m_Trunc(m_Value(V)))))
351  return nullptr;
352 
353  C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1;
354  NeedAnd = true;
355  } else {
356  return nullptr;
357  }
358 
359  const APInt *C2;
360  bool OrOnTrueVal = false;
361  bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)));
362  if (!OrOnFalseVal)
363  OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2)));
364 
365  if (!OrOnFalseVal && !OrOnTrueVal)
366  return nullptr;
367 
368  Value *Y = OrOnFalseVal ? TrueVal : FalseVal;
369 
370  unsigned C2Log = C2->logBase2();
371 
372  bool NeedXor = (!IsEqualZero && OrOnFalseVal) || (IsEqualZero && OrOnTrueVal);
373  bool NeedShift = C1Log != C2Log;
374  bool NeedZExtTrunc = Y->getType()->getIntegerBitWidth() !=
375  V->getType()->getIntegerBitWidth();
376 
377  // Make sure we don't create more instructions than we save.
378  Value *Or = OrOnFalseVal ? FalseVal : TrueVal;
379  if ((NeedShift + NeedXor + NeedZExtTrunc) >
380  (IC->hasOneUse() + Or->hasOneUse()))
381  return nullptr;
382 
383  if (NeedAnd) {
384  // Insert the AND instruction on the input to the truncate.
386  V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), C1));
387  }
388 
389  if (C2Log > C1Log) {
390  V = Builder.CreateZExtOrTrunc(V, Y->getType());
391  V = Builder.CreateShl(V, C2Log - C1Log);
392  } else if (C1Log > C2Log) {
393  V = Builder.CreateLShr(V, C1Log - C2Log);
394  V = Builder.CreateZExtOrTrunc(V, Y->getType());
395  } else
396  V = Builder.CreateZExtOrTrunc(V, Y->getType());
397 
398  if (NeedXor)
399  V = Builder.CreateXor(V, *C2);
400 
401  return Builder.CreateOr(V, Y);
402 }
403 
404 /// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single
405 /// call to cttz/ctlz with flag 'is_zero_undef' cleared.
406 ///
407 /// For example, we can fold the following code sequence:
408 /// \code
409 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
410 /// %1 = icmp ne i32 %x, 0
411 /// %2 = select i1 %1, i32 %0, i32 32
412 /// \code
413 ///
414 /// into:
415 /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
416 static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
417  InstCombiner::BuilderTy &Builder) {
418  ICmpInst::Predicate Pred = ICI->getPredicate();
419  Value *CmpLHS = ICI->getOperand(0);
420  Value *CmpRHS = ICI->getOperand(1);
421 
422  // Check if the condition value compares a value for equality against zero.
423  if (!ICI->isEquality() || !match(CmpRHS, m_Zero()))
424  return nullptr;
425 
426  Value *Count = FalseVal;
427  Value *ValueOnZero = TrueVal;
428  if (Pred == ICmpInst::ICMP_NE)
429  std::swap(Count, ValueOnZero);
430 
431  // Skip zero extend/truncate.
432  Value *V = nullptr;
433  if (match(Count, m_ZExt(m_Value(V))) ||
434  match(Count, m_Trunc(m_Value(V))))
435  Count = V;
436 
437  // Check if the value propagated on zero is a constant number equal to the
438  // sizeof in bits of 'Count'.
439  unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits();
440  if (!match(ValueOnZero, m_SpecificInt(SizeOfInBits)))
441  return nullptr;
442 
443  // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
444  // input to the cttz/ctlz is used as LHS for the compare instruction.
445  if (match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) ||
446  match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS)))) {
447  IntrinsicInst *II = cast<IntrinsicInst>(Count);
448  // Explicitly clear the 'undef_on_zero' flag.
449  IntrinsicInst *NewI = cast<IntrinsicInst>(II->clone());
450  Type *Ty = NewI->getArgOperand(1)->getType();
451  NewI->setArgOperand(1, Constant::getNullValue(Ty));
452  Builder.Insert(NewI);
453  return Builder.CreateZExtOrTrunc(NewI, ValueOnZero->getType());
454  }
455 
456  return nullptr;
457 }
458 
459 /// Return true if we find and adjust an icmp+select pattern where the compare
460 /// is with a constant that can be incremented or decremented to match the
461 /// minimum or maximum idiom.
462 static bool adjustMinMax(SelectInst &Sel, ICmpInst &Cmp) {
463  ICmpInst::Predicate Pred = Cmp.getPredicate();
464  Value *CmpLHS = Cmp.getOperand(0);
465  Value *CmpRHS = Cmp.getOperand(1);
466  Value *TrueVal = Sel.getTrueValue();
467  Value *FalseVal = Sel.getFalseValue();
468 
469  // We may move or edit the compare, so make sure the select is the only user.
470  const APInt *CmpC;
471  if (!Cmp.hasOneUse() || !match(CmpRHS, m_APInt(CmpC)))
472  return false;
473 
474  // These transforms only work for selects of integers or vector selects of
475  // integer vectors.
476  Type *SelTy = Sel.getType();
477  auto *SelEltTy = dyn_cast<IntegerType>(SelTy->getScalarType());
478  if (!SelEltTy || SelTy->isVectorTy() != Cmp.getType()->isVectorTy())
479  return false;
480 
481  Constant *AdjustedRHS;
482  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT)
483  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC + 1);
484  else if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT)
485  AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC - 1);
486  else
487  return false;
488 
489  // X > C ? X : C+1 --> X < C+1 ? C+1 : X
490  // X < C ? X : C-1 --> X > C-1 ? C-1 : X
491  if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
492  (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
493  ; // Nothing to do here. Values match without any sign/zero extension.
494  }
495  // Types do not match. Instead of calculating this with mixed types, promote
496  // all to the larger type. This enables scalar evolution to analyze this
497  // expression.
498  else if (CmpRHS->getType()->getScalarSizeInBits() < SelEltTy->getBitWidth()) {
499  Constant *SextRHS = ConstantExpr::getSExt(AdjustedRHS, SelTy);
500 
501  // X = sext x; x >s c ? X : C+1 --> X = sext x; X <s C+1 ? C+1 : X
502  // X = sext x; x <s c ? X : C-1 --> X = sext x; X >s C-1 ? C-1 : X
503  // X = sext x; x >u c ? X : C+1 --> X = sext x; X <u C+1 ? C+1 : X
504  // X = sext x; x <u c ? X : C-1 --> X = sext x; X >u C-1 ? C-1 : X
505  if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) && SextRHS == FalseVal) {
506  CmpLHS = TrueVal;
507  AdjustedRHS = SextRHS;
508  } else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) &&
509  SextRHS == TrueVal) {
510  CmpLHS = FalseVal;
511  AdjustedRHS = SextRHS;
512  } else if (Cmp.isUnsigned()) {
513  Constant *ZextRHS = ConstantExpr::getZExt(AdjustedRHS, SelTy);
514  // X = zext x; x >u c ? X : C+1 --> X = zext x; X <u C+1 ? C+1 : X
515  // X = zext x; x <u c ? X : C-1 --> X = zext x; X >u C-1 ? C-1 : X
516  // zext + signed compare cannot be changed:
517  // 0xff <s 0x00, but 0x00ff >s 0x0000
518  if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) && ZextRHS == FalseVal) {
519  CmpLHS = TrueVal;
520  AdjustedRHS = ZextRHS;
521  } else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) &&
522  ZextRHS == TrueVal) {
523  CmpLHS = FalseVal;
524  AdjustedRHS = ZextRHS;
525  } else {
526  return false;
527  }
528  } else {
529  return false;
530  }
531  } else {
532  return false;
533  }
534 
535  Pred = ICmpInst::getSwappedPredicate(Pred);
536  CmpRHS = AdjustedRHS;
537  std::swap(FalseVal, TrueVal);
538  Cmp.setPredicate(Pred);
539  Cmp.setOperand(0, CmpLHS);
540  Cmp.setOperand(1, CmpRHS);
541  Sel.setOperand(1, TrueVal);
542  Sel.setOperand(2, FalseVal);
543  Sel.swapProfMetadata();
544 
545  // Move the compare instruction right before the select instruction. Otherwise
546  // the sext/zext value may be defined after the compare instruction uses it.
547  Cmp.moveBefore(&Sel);
548 
549  return true;
550 }
551 
552 /// If this is an integer min/max (icmp + select) with a constant operand,
553 /// create the canonical icmp for the min/max operation and canonicalize the
554 /// constant to the 'false' operand of the select:
555 /// select (icmp Pred X, C1), C2, X --> select (icmp Pred' X, C2), X, C2
556 /// Note: if C1 != C2, this will change the icmp constant to the existing
557 /// constant operand of the select.
558 static Instruction *
559 canonicalizeMinMaxWithConstant(SelectInst &Sel, ICmpInst &Cmp,
560  InstCombiner::BuilderTy &Builder) {
561  if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
562  return nullptr;
563 
564  // Canonicalize the compare predicate based on whether we have min or max.
565  Value *LHS, *RHS;
566  ICmpInst::Predicate NewPred;
567  SelectPatternResult SPR = matchSelectPattern(&Sel, LHS, RHS);
568  switch (SPR.Flavor) {
569  case SPF_SMIN: NewPred = ICmpInst::ICMP_SLT; break;
570  case SPF_UMIN: NewPred = ICmpInst::ICMP_ULT; break;
571  case SPF_SMAX: NewPred = ICmpInst::ICMP_SGT; break;
572  case SPF_UMAX: NewPred = ICmpInst::ICMP_UGT; break;
573  default: return nullptr;
574  }
575 
576  // Is this already canonical?
577  if (Cmp.getOperand(0) == LHS && Cmp.getOperand(1) == RHS &&
578  Cmp.getPredicate() == NewPred)
579  return nullptr;
580 
581  // Create the canonical compare and plug it into the select.
582  Sel.setCondition(Builder.CreateICmp(NewPred, LHS, RHS));
583 
584  // If the select operands did not change, we're done.
585  if (Sel.getTrueValue() == LHS && Sel.getFalseValue() == RHS)
586  return &Sel;
587 
588  // If we are swapping the select operands, swap the metadata too.
589  assert(Sel.getTrueValue() == RHS && Sel.getFalseValue() == LHS &&
590  "Unexpected results from matchSelectPattern");
591  Sel.setTrueValue(LHS);
592  Sel.setFalseValue(RHS);
593  Sel.swapProfMetadata();
594  return &Sel;
595 }
596 
597 /// Visit a SelectInst that has an ICmpInst as its first operand.
598 Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI,
599  ICmpInst *ICI) {
600  if (Instruction *NewSel = canonicalizeMinMaxWithConstant(SI, *ICI, Builder))
601  return NewSel;
602 
603  bool Changed = adjustMinMax(SI, *ICI);
604 
605  ICmpInst::Predicate Pred = ICI->getPredicate();
606  Value *CmpLHS = ICI->getOperand(0);
607  Value *CmpRHS = ICI->getOperand(1);
608  Value *TrueVal = SI.getTrueValue();
609  Value *FalseVal = SI.getFalseValue();
610 
611  // Transform (X >s -1) ? C1 : C2 --> ((X >>s 31) & (C2 - C1)) + C1
612  // and (X <s 0) ? C2 : C1 --> ((X >>s 31) & (C2 - C1)) + C1
613  // FIXME: Type and constness constraints could be lifted, but we have to
614  // watch code size carefully. We should consider xor instead of
615  // sub/add when we decide to do that.
616  if (IntegerType *Ty = dyn_cast<IntegerType>(CmpLHS->getType())) {
617  if (TrueVal->getType() == Ty) {
618  if (ConstantInt *Cmp = dyn_cast<ConstantInt>(CmpRHS)) {
619  ConstantInt *C1 = nullptr, *C2 = nullptr;
620  if (Pred == ICmpInst::ICMP_SGT && Cmp->isMinusOne()) {
621  C1 = dyn_cast<ConstantInt>(TrueVal);
622  C2 = dyn_cast<ConstantInt>(FalseVal);
623  } else if (Pred == ICmpInst::ICMP_SLT && Cmp->isZero()) {
624  C1 = dyn_cast<ConstantInt>(FalseVal);
625  C2 = dyn_cast<ConstantInt>(TrueVal);
626  }
627  if (C1 && C2) {
628  // This shift results in either -1 or 0.
629  Value *AShr = Builder.CreateAShr(CmpLHS, Ty->getBitWidth() - 1);
630 
631  // Check if we can express the operation with a single or.
632  if (C2->isMinusOne())
633  return replaceInstUsesWith(SI, Builder.CreateOr(AShr, C1));
634 
635  Value *And = Builder.CreateAnd(AShr, C2->getValue() - C1->getValue());
636  return replaceInstUsesWith(SI, Builder.CreateAdd(And, C1));
637  }
638  }
639  }
640  }
641 
642  // NOTE: if we wanted to, this is where to detect integer MIN/MAX
643 
644  if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
645  if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
646  // Transform (X == C) ? X : Y -> (X == C) ? C : Y
647  SI.setOperand(1, CmpRHS);
648  Changed = true;
649  } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
650  // Transform (X != C) ? Y : X -> (X != C) ? Y : C
651  SI.setOperand(2, CmpRHS);
652  Changed = true;
653  }
654  }
655 
656  // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring
657  // decomposeBitTestICmp() might help.
658  {
659  unsigned BitWidth =
660  DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
661  APInt MinSignedValue = APInt::getSignedMinValue(BitWidth);
662  Value *X;
663  const APInt *Y, *C;
664  bool TrueWhenUnset;
665  bool IsBitTest = false;
666  if (ICmpInst::isEquality(Pred) &&
667  match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) &&
668  match(CmpRHS, m_Zero())) {
669  IsBitTest = true;
670  TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
671  } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
672  X = CmpLHS;
673  Y = &MinSignedValue;
674  IsBitTest = true;
675  TrueWhenUnset = false;
676  } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
677  X = CmpLHS;
678  Y = &MinSignedValue;
679  IsBitTest = true;
680  TrueWhenUnset = true;
681  }
682  if (IsBitTest) {
683  Value *V = nullptr;
684  // (X & Y) == 0 ? X : X ^ Y --> X & ~Y
685  if (TrueWhenUnset && TrueVal == X &&
686  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
687  V = Builder.CreateAnd(X, ~(*Y));
688  // (X & Y) != 0 ? X ^ Y : X --> X & ~Y
689  else if (!TrueWhenUnset && FalseVal == X &&
690  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
691  V = Builder.CreateAnd(X, ~(*Y));
692  // (X & Y) == 0 ? X ^ Y : X --> X | Y
693  else if (TrueWhenUnset && FalseVal == X &&
694  match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
695  V = Builder.CreateOr(X, *Y);
696  // (X & Y) != 0 ? X : X ^ Y --> X | Y
697  else if (!TrueWhenUnset && TrueVal == X &&
698  match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
699  V = Builder.CreateOr(X, *Y);
700 
701  if (V)
702  return replaceInstUsesWith(SI, V);
703  }
704  }
705 
706  if (Value *V = foldSelectICmpAndOr(SI, TrueVal, FalseVal, Builder))
707  return replaceInstUsesWith(SI, V);
708 
709  if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
710  return replaceInstUsesWith(SI, V);
711 
712  return Changed ? &SI : nullptr;
713 }
714 
715 
716 /// SI is a select whose condition is a PHI node (but the two may be in
717 /// different blocks). See if the true/false values (V) are live in all of the
718 /// predecessor blocks of the PHI. For example, cases like this can't be mapped:
719 ///
720 /// X = phi [ C1, BB1], [C2, BB2]
721 /// Y = add
722 /// Z = select X, Y, 0
723 ///
724 /// because Y is not live in BB1/BB2.
725 ///
726 static bool canSelectOperandBeMappingIntoPredBlock(const Value *V,
727  const SelectInst &SI) {
728  // If the value is a non-instruction value like a constant or argument, it
729  // can always be mapped.
730  const Instruction *I = dyn_cast<Instruction>(V);
731  if (!I) return true;
732 
733  // If V is a PHI node defined in the same block as the condition PHI, we can
734  // map the arguments.
735  const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
736 
737  if (const PHINode *VP = dyn_cast<PHINode>(I))
738  if (VP->getParent() == CondPHI->getParent())
739  return true;
740 
741  // Otherwise, if the PHI and select are defined in the same block and if V is
742  // defined in a different block, then we can transform it.
743  if (SI.getParent() == CondPHI->getParent() &&
744  I->getParent() != CondPHI->getParent())
745  return true;
746 
747  // Otherwise we have a 'hard' case and we can't tell without doing more
748  // detailed dominator based analysis, punt.
749  return false;
750 }
751 
752 /// We have an SPF (e.g. a min or max) of an SPF of the form:
753 /// SPF2(SPF1(A, B), C)
754 Instruction *InstCombiner::foldSPFofSPF(Instruction *Inner,
755  SelectPatternFlavor SPF1,
756  Value *A, Value *B,
757  Instruction &Outer,
758  SelectPatternFlavor SPF2, Value *C) {
759  if (Outer.getType() != Inner->getType())
760  return nullptr;
761 
762  if (C == A || C == B) {
763  // MAX(MAX(A, B), B) -> MAX(A, B)
764  // MIN(MIN(a, b), a) -> MIN(a, b)
765  if (SPF1 == SPF2)
766  return replaceInstUsesWith(Outer, Inner);
767 
768  // MAX(MIN(a, b), a) -> a
769  // MIN(MAX(a, b), a) -> a
770  if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
771  (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
772  (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
773  (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
774  return replaceInstUsesWith(Outer, C);
775  }
776 
777  if (SPF1 == SPF2) {
778  const APInt *CB, *CC;
779  if (match(B, m_APInt(CB)) && match(C, m_APInt(CC))) {
780  // MIN(MIN(A, 23), 97) -> MIN(A, 23)
781  // MAX(MAX(A, 97), 23) -> MAX(A, 97)
782  if ((SPF1 == SPF_UMIN && CB->ule(*CC)) ||
783  (SPF1 == SPF_SMIN && CB->sle(*CC)) ||
784  (SPF1 == SPF_UMAX && CB->uge(*CC)) ||
785  (SPF1 == SPF_SMAX && CB->sge(*CC)))
786  return replaceInstUsesWith(Outer, Inner);
787 
788  // MIN(MIN(A, 97), 23) -> MIN(A, 23)
789  // MAX(MAX(A, 23), 97) -> MAX(A, 97)
790  if ((SPF1 == SPF_UMIN && CB->ugt(*CC)) ||
791  (SPF1 == SPF_SMIN && CB->sgt(*CC)) ||
792  (SPF1 == SPF_UMAX && CB->ult(*CC)) ||
793  (SPF1 == SPF_SMAX && CB->slt(*CC))) {
794  Outer.replaceUsesOfWith(Inner, A);
795  return &Outer;
796  }
797  }
798  }
799 
800  // ABS(ABS(X)) -> ABS(X)
801  // NABS(NABS(X)) -> NABS(X)
802  if (SPF1 == SPF2 && (SPF1 == SPF_ABS || SPF1 == SPF_NABS)) {
803  return replaceInstUsesWith(Outer, Inner);
804  }
805 
806  // ABS(NABS(X)) -> ABS(X)
807  // NABS(ABS(X)) -> NABS(X)
808  if ((SPF1 == SPF_ABS && SPF2 == SPF_NABS) ||
809  (SPF1 == SPF_NABS && SPF2 == SPF_ABS)) {
810  SelectInst *SI = cast<SelectInst>(Inner);
811  Value *NewSI =
812  Builder.CreateSelect(SI->getCondition(), SI->getFalseValue(),
813  SI->getTrueValue(), SI->getName(), SI);
814  return replaceInstUsesWith(Outer, NewSI);
815  }
816 
817  auto IsFreeOrProfitableToInvert =
818  [&](Value *V, Value *&NotV, bool &ElidesXor) {
819  if (match(V, m_Not(m_Value(NotV)))) {
820  // If V has at most 2 uses then we can get rid of the xor operation
821  // entirely.
822  ElidesXor |= !V->hasNUsesOrMore(3);
823  return true;
824  }
825 
826  if (IsFreeToInvert(V, !V->hasNUsesOrMore(3))) {
827  NotV = nullptr;
828  return true;
829  }
830 
831  return false;
832  };
833 
834  Value *NotA, *NotB, *NotC;
835  bool ElidesXor = false;
836 
837  // MIN(MIN(~A, ~B), ~C) == ~MAX(MAX(A, B), C)
838  // MIN(MAX(~A, ~B), ~C) == ~MAX(MIN(A, B), C)
839  // MAX(MIN(~A, ~B), ~C) == ~MIN(MAX(A, B), C)
840  // MAX(MAX(~A, ~B), ~C) == ~MIN(MIN(A, B), C)
841  //
842  // This transform is performance neutral if we can elide at least one xor from
843  // the set of three operands, since we'll be tacking on an xor at the very
844  // end.
847  IsFreeOrProfitableToInvert(A, NotA, ElidesXor) &&
848  IsFreeOrProfitableToInvert(B, NotB, ElidesXor) &&
849  IsFreeOrProfitableToInvert(C, NotC, ElidesXor) && ElidesXor) {
850  if (!NotA)
851  NotA = Builder.CreateNot(A);
852  if (!NotB)
853  NotB = Builder.CreateNot(B);
854  if (!NotC)
855  NotC = Builder.CreateNot(C);
856 
858  Builder, getInverseMinMaxSelectPattern(SPF1), NotA, NotB);
859  Value *NewOuter = Builder.CreateNot(generateMinMaxSelectPattern(
860  Builder, getInverseMinMaxSelectPattern(SPF2), NewInner, NotC));
861  return replaceInstUsesWith(Outer, NewOuter);
862  }
863 
864  return nullptr;
865 }
866 
867 /// If one of the constants is zero (we know they can't both be) and we have an
868 /// icmp instruction with zero, and we have an 'and' with the non-constant value
869 /// and a power of two we can turn the select into a shift on the result of the
870 /// 'and'.
871 static Value *foldSelectICmpAnd(const SelectInst &SI, APInt TrueVal,
872  APInt FalseVal,
873  InstCombiner::BuilderTy &Builder) {
874  const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition());
875  if (!IC || !IC->isEquality() || !SI.getType()->isIntegerTy())
876  return nullptr;
877 
878  if (!match(IC->getOperand(1), m_Zero()))
879  return nullptr;
880 
881  ConstantInt *AndRHS;
882  Value *LHS = IC->getOperand(0);
883  if (!match(LHS, m_And(m_Value(), m_ConstantInt(AndRHS))))
884  return nullptr;
885 
886  // If both select arms are non-zero see if we have a select of the form
887  // 'x ? 2^n + C : C'. Then we can offset both arms by C, use the logic
888  // for 'x ? 2^n : 0' and fix the thing up at the end.
889  APInt Offset(TrueVal.getBitWidth(), 0);
890  if (!TrueVal.isNullValue() && !FalseVal.isNullValue()) {
891  if ((TrueVal - FalseVal).isPowerOf2())
892  Offset = FalseVal;
893  else if ((FalseVal - TrueVal).isPowerOf2())
894  Offset = TrueVal;
895  else
896  return nullptr;
897 
898  // Adjust TrueVal and FalseVal to the offset.
899  TrueVal -= Offset;
900  FalseVal -= Offset;
901  }
902 
903  // Make sure the mask in the 'and' and one of the select arms is a power of 2.
904  if (!AndRHS->getValue().isPowerOf2() ||
905  (!TrueVal.isPowerOf2() && !FalseVal.isPowerOf2()))
906  return nullptr;
907 
908  // Determine which shift is needed to transform result of the 'and' into the
909  // desired result.
910  const APInt &ValC = !TrueVal.isNullValue() ? TrueVal : FalseVal;
911  unsigned ValZeros = ValC.logBase2();
912  unsigned AndZeros = AndRHS->getValue().logBase2();
913 
914  // If types don't match we can still convert the select by introducing a zext
915  // or a trunc of the 'and'. The trunc case requires that all of the truncated
916  // bits are zero, we can figure that out by looking at the 'and' mask.
917  if (AndZeros >= ValC.getBitWidth())
918  return nullptr;
919 
920  Value *V = Builder.CreateZExtOrTrunc(LHS, SI.getType());
921  if (ValZeros > AndZeros)
922  V = Builder.CreateShl(V, ValZeros - AndZeros);
923  else if (ValZeros < AndZeros)
924  V = Builder.CreateLShr(V, AndZeros - ValZeros);
925 
926  // Okay, now we know that everything is set up, we just don't know whether we
927  // have a icmp_ne or icmp_eq and whether the true or false val is the zero.
928  bool ShouldNotVal = !TrueVal.isNullValue();
929  ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
930  if (ShouldNotVal)
931  V = Builder.CreateXor(V, ValC);
932 
933  // Apply an offset if needed.
934  if (!Offset.isNullValue())
935  V = Builder.CreateAdd(V, ConstantInt::get(V->getType(), Offset));
936  return V;
937 }
938 
939 /// Turn select C, (X + Y), (X - Y) --> (X + (select C, Y, (-Y))).
940 /// This is even legal for FP.
941 static Instruction *foldAddSubSelect(SelectInst &SI,
942  InstCombiner::BuilderTy &Builder) {
943  Value *CondVal = SI.getCondition();
944  Value *TrueVal = SI.getTrueValue();
945  Value *FalseVal = SI.getFalseValue();
946  auto *TI = dyn_cast<Instruction>(TrueVal);
947  auto *FI = dyn_cast<Instruction>(FalseVal);
948  if (!TI || !FI || !TI->hasOneUse() || !FI->hasOneUse())
949  return nullptr;
950 
951  Instruction *AddOp = nullptr, *SubOp = nullptr;
952  if ((TI->getOpcode() == Instruction::Sub &&
953  FI->getOpcode() == Instruction::Add) ||
954  (TI->getOpcode() == Instruction::FSub &&
955  FI->getOpcode() == Instruction::FAdd)) {
956  AddOp = FI;
957  SubOp = TI;
958  } else if ((FI->getOpcode() == Instruction::Sub &&
959  TI->getOpcode() == Instruction::Add) ||
960  (FI->getOpcode() == Instruction::FSub &&
961  TI->getOpcode() == Instruction::FAdd)) {
962  AddOp = TI;
963  SubOp = FI;
964  }
965 
966  if (AddOp) {
967  Value *OtherAddOp = nullptr;
968  if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
969  OtherAddOp = AddOp->getOperand(1);
970  } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
971  OtherAddOp = AddOp->getOperand(0);
972  }
973 
974  if (OtherAddOp) {
975  // So at this point we know we have (Y -> OtherAddOp):
976  // select C, (add X, Y), (sub X, Z)
977  Value *NegVal; // Compute -Z
978  if (SI.getType()->isFPOrFPVectorTy()) {
979  NegVal = Builder.CreateFNeg(SubOp->getOperand(1));
980  if (Instruction *NegInst = dyn_cast<Instruction>(NegVal)) {
982  Flags &= SubOp->getFastMathFlags();
983  NegInst->setFastMathFlags(Flags);
984  }
985  } else {
986  NegVal = Builder.CreateNeg(SubOp->getOperand(1));
987  }
988 
989  Value *NewTrueOp = OtherAddOp;
990  Value *NewFalseOp = NegVal;
991  if (AddOp != TI)
992  std::swap(NewTrueOp, NewFalseOp);
993  Value *NewSel = Builder.CreateSelect(CondVal, NewTrueOp, NewFalseOp,
994  SI.getName() + ".p", &SI);
995 
996  if (SI.getType()->isFPOrFPVectorTy()) {
997  Instruction *RI =
998  BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel);
999 
1001  Flags &= SubOp->getFastMathFlags();
1002  RI->setFastMathFlags(Flags);
1003  return RI;
1004  } else
1005  return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
1006  }
1007  }
1008  return nullptr;
1009 }
1010 
1011 Instruction *InstCombiner::foldSelectExtConst(SelectInst &Sel) {
1012  Instruction *ExtInst;
1013  if (!match(Sel.getTrueValue(), m_Instruction(ExtInst)) &&
1014  !match(Sel.getFalseValue(), m_Instruction(ExtInst)))
1015  return nullptr;
1016 
1017  auto ExtOpcode = ExtInst->getOpcode();
1018  if (ExtOpcode != Instruction::ZExt && ExtOpcode != Instruction::SExt)
1019  return nullptr;
1020 
1021  // TODO: Handle larger types? That requires adjusting FoldOpIntoSelect too.
1022  Value *X = ExtInst->getOperand(0);
1023  Type *SmallType = X->getType();
1024  if (!SmallType->isIntOrIntVectorTy(1))
1025  return nullptr;
1026 
1027  Constant *C;
1028  if (!match(Sel.getTrueValue(), m_Constant(C)) &&
1029  !match(Sel.getFalseValue(), m_Constant(C)))
1030  return nullptr;
1031 
1032  // If the constant is the same after truncation to the smaller type and
1033  // extension to the original type, we can narrow the select.
1034  Value *Cond = Sel.getCondition();
1035  Type *SelType = Sel.getType();
1036  Constant *TruncC = ConstantExpr::getTrunc(C, SmallType);
1037  Constant *ExtC = ConstantExpr::getCast(ExtOpcode, TruncC, SelType);
1038  if (ExtC == C) {
1039  Value *TruncCVal = cast<Value>(TruncC);
1040  if (ExtInst == Sel.getFalseValue())
1041  std::swap(X, TruncCVal);
1042 
1043  // select Cond, (ext X), C --> ext(select Cond, X, C')
1044  // select Cond, C, (ext X) --> ext(select Cond, C', X)
1045  Value *NewSel = Builder.CreateSelect(Cond, X, TruncCVal, "narrow", &Sel);
1046  return CastInst::Create(Instruction::CastOps(ExtOpcode), NewSel, SelType);
1047  }
1048 
1049  // If one arm of the select is the extend of the condition, replace that arm
1050  // with the extension of the appropriate known bool value.
1051  if (Cond == X) {
1052  if (ExtInst == Sel.getTrueValue()) {
1053  // select X, (sext X), C --> select X, -1, C
1054  // select X, (zext X), C --> select X, 1, C
1055  Constant *One = ConstantInt::getTrue(SmallType);
1056  Constant *AllOnesOrOne = ConstantExpr::getCast(ExtOpcode, One, SelType);
1057  return SelectInst::Create(Cond, AllOnesOrOne, C, "", nullptr, &Sel);
1058  } else {
1059  // select X, C, (sext X) --> select X, C, 0
1060  // select X, C, (zext X) --> select X, C, 0
1062  return SelectInst::Create(Cond, C, Zero, "", nullptr, &Sel);
1063  }
1064  }
1065 
1066  return nullptr;
1067 }
1068 
1069 /// Try to transform a vector select with a constant condition vector into a
1070 /// shuffle for easier combining with other shuffles and insert/extract.
1071 static Instruction *canonicalizeSelectToShuffle(SelectInst &SI) {
1072  Value *CondVal = SI.getCondition();
1073  Constant *CondC;
1074  if (!CondVal->getType()->isVectorTy() || !match(CondVal, m_Constant(CondC)))
1075  return nullptr;
1076 
1077  unsigned NumElts = CondVal->getType()->getVectorNumElements();
1079  Mask.reserve(NumElts);
1080  Type *Int32Ty = Type::getInt32Ty(CondVal->getContext());
1081  for (unsigned i = 0; i != NumElts; ++i) {
1082  Constant *Elt = CondC->getAggregateElement(i);
1083  if (!Elt)
1084  return nullptr;
1085 
1086  if (Elt->isOneValue()) {
1087  // If the select condition element is true, choose from the 1st vector.
1088  Mask.push_back(ConstantInt::get(Int32Ty, i));
1089  } else if (Elt->isNullValue()) {
1090  // If the select condition element is false, choose from the 2nd vector.
1091  Mask.push_back(ConstantInt::get(Int32Ty, i + NumElts));
1092  } else if (isa<UndefValue>(Elt)) {
1093  // Undef in a select condition (choose one of the operands) does not mean
1094  // the same thing as undef in a shuffle mask (any value is acceptable), so
1095  // give up.
1096  return nullptr;
1097  } else {
1098  // Bail out on a constant expression.
1099  return nullptr;
1100  }
1101  }
1102 
1103  return new ShuffleVectorInst(SI.getTrueValue(), SI.getFalseValue(),
1104  ConstantVector::get(Mask));
1105 }
1106 
1107 /// Reuse bitcasted operands between a compare and select:
1108 /// select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
1109 /// bitcast (select (cmp (bitcast C), (bitcast D)), (bitcast C), (bitcast D))
1110 static Instruction *foldSelectCmpBitcasts(SelectInst &Sel,
1111  InstCombiner::BuilderTy &Builder) {
1112  Value *Cond = Sel.getCondition();
1113  Value *TVal = Sel.getTrueValue();
1114  Value *FVal = Sel.getFalseValue();
1115 
1116  CmpInst::Predicate Pred;
1117  Value *A, *B;
1118  if (!match(Cond, m_Cmp(Pred, m_Value(A), m_Value(B))))
1119  return nullptr;
1120 
1121  // The select condition is a compare instruction. If the select's true/false
1122  // values are already the same as the compare operands, there's nothing to do.
1123  if (TVal == A || TVal == B || FVal == A || FVal == B)
1124  return nullptr;
1125 
1126  Value *C, *D;
1127  if (!match(A, m_BitCast(m_Value(C))) || !match(B, m_BitCast(m_Value(D))))
1128  return nullptr;
1129 
1130  // select (cmp (bitcast C), (bitcast D)), (bitcast TSrc), (bitcast FSrc)
1131  Value *TSrc, *FSrc;
1132  if (!match(TVal, m_BitCast(m_Value(TSrc))) ||
1133  !match(FVal, m_BitCast(m_Value(FSrc))))
1134  return nullptr;
1135 
1136  // If the select true/false values are *different bitcasts* of the same source
1137  // operands, make the select operands the same as the compare operands and
1138  // cast the result. This is the canonical select form for min/max.
1139  Value *NewSel;
1140  if (TSrc == C && FSrc == D) {
1141  // select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) -->
1142  // bitcast (select (cmp A, B), A, B)
1143  NewSel = Builder.CreateSelect(Cond, A, B, "", &Sel);
1144  } else if (TSrc == D && FSrc == C) {
1145  // select (cmp (bitcast C), (bitcast D)), (bitcast' D), (bitcast' C) -->
1146  // bitcast (select (cmp A, B), B, A)
1147  NewSel = Builder.CreateSelect(Cond, B, A, "", &Sel);
1148  } else {
1149  return nullptr;
1150  }
1151  return CastInst::CreateBitOrPointerCast(NewSel, Sel.getType());
1152 }
1153 
1155  Value *CondVal = SI.getCondition();
1156  Value *TrueVal = SI.getTrueValue();
1157  Value *FalseVal = SI.getFalseValue();
1158  Type *SelType = SI.getType();
1159 
1160  if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal,
1161  SQ.getWithInstruction(&SI)))
1162  return replaceInstUsesWith(SI, V);
1163 
1164  if (Instruction *I = canonicalizeSelectToShuffle(SI))
1165  return I;
1166 
1167  // Canonicalize a one-use integer compare with a non-canonical predicate by
1168  // inverting the predicate and swapping the select operands. This matches a
1169  // compare canonicalization for conditional branches.
1170  // TODO: Should we do the same for FP compares?
1171  CmpInst::Predicate Pred;
1172  if (match(CondVal, m_OneUse(m_ICmp(Pred, m_Value(), m_Value()))) &&
1173  !isCanonicalPredicate(Pred)) {
1174  // Swap true/false values and condition.
1175  CmpInst *Cond = cast<CmpInst>(CondVal);
1177  SI.setOperand(1, FalseVal);
1178  SI.setOperand(2, TrueVal);
1179  SI.swapProfMetadata();
1180  Worklist.Add(Cond);
1181  return &SI;
1182  }
1183 
1184  if (SelType->isIntOrIntVectorTy(1) &&
1185  TrueVal->getType() == CondVal->getType()) {
1186  if (match(TrueVal, m_One())) {
1187  // Change: A = select B, true, C --> A = or B, C
1188  return BinaryOperator::CreateOr(CondVal, FalseVal);
1189  }
1190  if (match(TrueVal, m_Zero())) {
1191  // Change: A = select B, false, C --> A = and !B, C
1192  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1193  return BinaryOperator::CreateAnd(NotCond, FalseVal);
1194  }
1195  if (match(FalseVal, m_Zero())) {
1196  // Change: A = select B, C, false --> A = and B, C
1197  return BinaryOperator::CreateAnd(CondVal, TrueVal);
1198  }
1199  if (match(FalseVal, m_One())) {
1200  // Change: A = select B, C, true --> A = or !B, C
1201  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1202  return BinaryOperator::CreateOr(NotCond, TrueVal);
1203  }
1204 
1205  // select a, a, b -> a | b
1206  // select a, b, a -> a & b
1207  if (CondVal == TrueVal)
1208  return BinaryOperator::CreateOr(CondVal, FalseVal);
1209  if (CondVal == FalseVal)
1210  return BinaryOperator::CreateAnd(CondVal, TrueVal);
1211 
1212  // select a, ~a, b -> (~a) & b
1213  // select a, b, ~a -> (~a) | b
1214  if (match(TrueVal, m_Not(m_Specific(CondVal))))
1215  return BinaryOperator::CreateAnd(TrueVal, FalseVal);
1216  if (match(FalseVal, m_Not(m_Specific(CondVal))))
1217  return BinaryOperator::CreateOr(TrueVal, FalseVal);
1218  }
1219 
1220  // Selecting between two integer or vector splat integer constants?
1221  //
1222  // Note that we don't handle a scalar select of vectors:
1223  // select i1 %c, <2 x i8> <1, 1>, <2 x i8> <0, 0>
1224  // because that may need 3 instructions to splat the condition value:
1225  // extend, insertelement, shufflevector.
1226  if (SelType->isIntOrIntVectorTy() &&
1227  CondVal->getType()->isVectorTy() == SelType->isVectorTy()) {
1228  // select C, 1, 0 -> zext C to int
1229  if (match(TrueVal, m_One()) && match(FalseVal, m_Zero()))
1230  return new ZExtInst(CondVal, SelType);
1231 
1232  // select C, -1, 0 -> sext C to int
1233  if (match(TrueVal, m_AllOnes()) && match(FalseVal, m_Zero()))
1234  return new SExtInst(CondVal, SelType);
1235 
1236  // select C, 0, 1 -> zext !C to int
1237  if (match(TrueVal, m_Zero()) && match(FalseVal, m_One())) {
1238  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1239  return new ZExtInst(NotCond, SelType);
1240  }
1241 
1242  // select C, 0, -1 -> sext !C to int
1243  if (match(TrueVal, m_Zero()) && match(FalseVal, m_AllOnes())) {
1244  Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName());
1245  return new SExtInst(NotCond, SelType);
1246  }
1247  }
1248 
1249  if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
1250  if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal))
1251  if (Value *V = foldSelectICmpAnd(SI, TrueValC->getValue(),
1252  FalseValC->getValue(), Builder))
1253  return replaceInstUsesWith(SI, V);
1254 
1255  // See if we are selecting two values based on a comparison of the two values.
1256  if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
1257  if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
1258  // Transform (X == Y) ? X : Y -> Y
1259  if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
1260  // This is not safe in general for floating point:
1261  // consider X== -0, Y== +0.
1262  // It becomes safe if either operand is a nonzero constant.
1263  ConstantFP *CFPt, *CFPf;
1264  if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
1265  !CFPt->getValueAPF().isZero()) ||
1266  ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
1267  !CFPf->getValueAPF().isZero()))
1268  return replaceInstUsesWith(SI, FalseVal);
1269  }
1270  // Transform (X une Y) ? X : Y -> X
1271  if (FCI->getPredicate() == FCmpInst::FCMP_UNE) {
1272  // This is not safe in general for floating point:
1273  // consider X== -0, Y== +0.
1274  // It becomes safe if either operand is a nonzero constant.
1275  ConstantFP *CFPt, *CFPf;
1276  if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
1277  !CFPt->getValueAPF().isZero()) ||
1278  ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
1279  !CFPf->getValueAPF().isZero()))
1280  return replaceInstUsesWith(SI, TrueVal);
1281  }
1282 
1283  // Canonicalize to use ordered comparisons by swapping the select
1284  // operands.
1285  //
1286  // e.g.
1287  // (X ugt Y) ? X : Y -> (X ole Y) ? Y : X
1288  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
1289  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
1290  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1291  Builder.setFastMathFlags(FCI->getFastMathFlags());
1292  Value *NewCond = Builder.CreateFCmp(InvPred, TrueVal, FalseVal,
1293  FCI->getName() + ".inv");
1294 
1295  return SelectInst::Create(NewCond, FalseVal, TrueVal,
1296  SI.getName() + ".p");
1297  }
1298 
1299  // NOTE: if we wanted to, this is where to detect MIN/MAX
1300  } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
1301  // Transform (X == Y) ? Y : X -> X
1302  if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
1303  // This is not safe in general for floating point:
1304  // consider X== -0, Y== +0.
1305  // It becomes safe if either operand is a nonzero constant.
1306  ConstantFP *CFPt, *CFPf;
1307  if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
1308  !CFPt->getValueAPF().isZero()) ||
1309  ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
1310  !CFPf->getValueAPF().isZero()))
1311  return replaceInstUsesWith(SI, FalseVal);
1312  }
1313  // Transform (X une Y) ? Y : X -> Y
1314  if (FCI->getPredicate() == FCmpInst::FCMP_UNE) {
1315  // This is not safe in general for floating point:
1316  // consider X== -0, Y== +0.
1317  // It becomes safe if either operand is a nonzero constant.
1318  ConstantFP *CFPt, *CFPf;
1319  if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
1320  !CFPt->getValueAPF().isZero()) ||
1321  ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
1322  !CFPf->getValueAPF().isZero()))
1323  return replaceInstUsesWith(SI, TrueVal);
1324  }
1325 
1326  // Canonicalize to use ordered comparisons by swapping the select
1327  // operands.
1328  //
1329  // e.g.
1330  // (X ugt Y) ? X : Y -> (X ole Y) ? X : Y
1331  if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
1332  FCmpInst::Predicate InvPred = FCI->getInversePredicate();
1333  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1334  Builder.setFastMathFlags(FCI->getFastMathFlags());
1335  Value *NewCond = Builder.CreateFCmp(InvPred, FalseVal, TrueVal,
1336  FCI->getName() + ".inv");
1337 
1338  return SelectInst::Create(NewCond, FalseVal, TrueVal,
1339  SI.getName() + ".p");
1340  }
1341 
1342  // NOTE: if we wanted to, this is where to detect MIN/MAX
1343  }
1344  // NOTE: if we wanted to, this is where to detect ABS
1345  }
1346 
1347  // See if we are selecting two values based on a comparison of the two values.
1348  if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
1349  if (Instruction *Result = foldSelectInstWithICmp(SI, ICI))
1350  return Result;
1351 
1352  if (Instruction *Add = foldAddSubSelect(SI, Builder))
1353  return Add;
1354 
1355  // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
1356  auto *TI = dyn_cast<Instruction>(TrueVal);
1357  auto *FI = dyn_cast<Instruction>(FalseVal);
1358  if (TI && FI && TI->getOpcode() == FI->getOpcode())
1359  if (Instruction *IV = foldSelectOpOp(SI, TI, FI))
1360  return IV;
1361 
1362  if (Instruction *I = foldSelectExtConst(SI))
1363  return I;
1364 
1365  // See if we can fold the select into one of our operands.
1366  if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) {
1367  if (Instruction *FoldI = foldSelectIntoOp(SI, TrueVal, FalseVal))
1368  return FoldI;
1369 
1370  Value *LHS, *RHS, *LHS2, *RHS2;
1371  Instruction::CastOps CastOp;
1372  SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp);
1373  auto SPF = SPR.Flavor;
1374 
1376  // Canonicalize so that type casts are outside select patterns.
1377  if (LHS->getType()->getPrimitiveSizeInBits() !=
1378  SelType->getPrimitiveSizeInBits()) {
1380 
1381  Value *Cmp;
1382  if (CmpInst::isIntPredicate(Pred)) {
1383  Cmp = Builder.CreateICmp(Pred, LHS, RHS);
1384  } else {
1385  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
1386  auto FMF = cast<FPMathOperator>(SI.getCondition())->getFastMathFlags();
1387  Builder.setFastMathFlags(FMF);
1388  Cmp = Builder.CreateFCmp(Pred, LHS, RHS);
1389  }
1390 
1391  Value *NewSI = Builder.CreateCast(
1392  CastOp, Builder.CreateSelect(Cmp, LHS, RHS, SI.getName(), &SI),
1393  SelType);
1394  return replaceInstUsesWith(SI, NewSI);
1395  }
1396  }
1397 
1398  if (SPF) {
1399  // MAX(MAX(a, b), a) -> MAX(a, b)
1400  // MIN(MIN(a, b), a) -> MIN(a, b)
1401  // MAX(MIN(a, b), a) -> a
1402  // MIN(MAX(a, b), a) -> a
1403  // ABS(ABS(a)) -> ABS(a)
1404  // NABS(NABS(a)) -> NABS(a)
1405  if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor)
1406  if (Instruction *R = foldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
1407  SI, SPF, RHS))
1408  return R;
1409  if (SelectPatternFlavor SPF2 = matchSelectPattern(RHS, LHS2, RHS2).Flavor)
1410  if (Instruction *R = foldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2,
1411  SI, SPF, LHS))
1412  return R;
1413  }
1414 
1415  // MAX(~a, ~b) -> ~MIN(a, b)
1416  if ((SPF == SPF_SMAX || SPF == SPF_UMAX) &&
1417  IsFreeToInvert(LHS, LHS->hasNUses(2)) &&
1418  IsFreeToInvert(RHS, RHS->hasNUses(2))) {
1419  // For this transform to be profitable, we need to eliminate at least two
1420  // 'not' instructions if we're going to add one 'not' instruction.
1421  int NumberOfNots =
1422  (LHS->hasNUses(2) && match(LHS, m_Not(m_Value()))) +
1423  (RHS->hasNUses(2) && match(RHS, m_Not(m_Value()))) +
1424  (SI.hasOneUse() && match(*SI.user_begin(), m_Not(m_Value())));
1425 
1426  if (NumberOfNots >= 2) {
1427  Value *NewLHS = Builder.CreateNot(LHS);
1428  Value *NewRHS = Builder.CreateNot(RHS);
1429  Value *NewCmp = SPF == SPF_SMAX ? Builder.CreateICmpSLT(NewLHS, NewRHS)
1430  : Builder.CreateICmpULT(NewLHS, NewRHS);
1431  Value *NewSI =
1432  Builder.CreateNot(Builder.CreateSelect(NewCmp, NewLHS, NewRHS));
1433  return replaceInstUsesWith(SI, NewSI);
1434  }
1435  }
1436 
1437  // TODO.
1438  // ABS(-X) -> ABS(X)
1439  }
1440 
1441  // See if we can fold the select into a phi node if the condition is a select.
1442  if (auto *PN = dyn_cast<PHINode>(SI.getCondition()))
1443  // The true/false values have to be live in the PHI predecessor's blocks.
1444  if (canSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
1445  canSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
1446  if (Instruction *NV = foldOpIntoPhi(SI, PN))
1447  return NV;
1448 
1449  if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
1450  if (TrueSI->getCondition()->getType() == CondVal->getType()) {
1451  // select(C, select(C, a, b), c) -> select(C, a, c)
1452  if (TrueSI->getCondition() == CondVal) {
1453  if (SI.getTrueValue() == TrueSI->getTrueValue())
1454  return nullptr;
1455  SI.setOperand(1, TrueSI->getTrueValue());
1456  return &SI;
1457  }
1458  // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
1459  // We choose this as normal form to enable folding on the And and shortening
1460  // paths for the values (this helps GetUnderlyingObjects() for example).
1461  if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
1462  Value *And = Builder.CreateAnd(CondVal, TrueSI->getCondition());
1463  SI.setOperand(0, And);
1464  SI.setOperand(1, TrueSI->getTrueValue());
1465  return &SI;
1466  }
1467  }
1468  }
1469  if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
1470  if (FalseSI->getCondition()->getType() == CondVal->getType()) {
1471  // select(C, a, select(C, b, c)) -> select(C, a, c)
1472  if (FalseSI->getCondition() == CondVal) {
1473  if (SI.getFalseValue() == FalseSI->getFalseValue())
1474  return nullptr;
1475  SI.setOperand(2, FalseSI->getFalseValue());
1476  return &SI;
1477  }
1478  // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
1479  if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
1480  Value *Or = Builder.CreateOr(CondVal, FalseSI->getCondition());
1481  SI.setOperand(0, Or);
1482  SI.setOperand(2, FalseSI->getFalseValue());
1483  return &SI;
1484  }
1485  }
1486  }
1487 
1488  if (BinaryOperator::isNot(CondVal)) {
1490  SI.setOperand(1, FalseVal);
1491  SI.setOperand(2, TrueVal);
1492  return &SI;
1493  }
1494 
1495  if (VectorType *VecTy = dyn_cast<VectorType>(SelType)) {
1496  unsigned VWidth = VecTy->getNumElements();
1497  APInt UndefElts(VWidth, 0);
1498  APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
1499  if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) {
1500  if (V != &SI)
1501  return replaceInstUsesWith(SI, V);
1502  return &SI;
1503  }
1504 
1505  if (isa<ConstantAggregateZero>(CondVal)) {
1506  return replaceInstUsesWith(SI, FalseVal);
1507  }
1508  }
1509 
1510  // See if we can determine the result of this select based on a dominating
1511  // condition.
1512  BasicBlock *Parent = SI.getParent();
1513  if (BasicBlock *Dom = Parent->getSinglePredecessor()) {
1514  auto *PBI = dyn_cast_or_null<BranchInst>(Dom->getTerminator());
1515  if (PBI && PBI->isConditional() &&
1516  PBI->getSuccessor(0) != PBI->getSuccessor(1) &&
1517  (PBI->getSuccessor(0) == Parent || PBI->getSuccessor(1) == Parent)) {
1518  bool CondIsFalse = PBI->getSuccessor(1) == Parent;
1519  Optional<bool> Implication = isImpliedCondition(
1520  PBI->getCondition(), SI.getCondition(), DL, CondIsFalse);
1521  if (Implication) {
1522  Value *V = *Implication ? TrueVal : FalseVal;
1523  return replaceInstUsesWith(SI, V);
1524  }
1525  }
1526  }
1527 
1528  // If we can compute the condition, there's no need for a select.
1529  // Like the above fold, we are attempting to reduce compile-time cost by
1530  // putting this fold here with limitations rather than in InstSimplify.
1531  // The motivation for this call into value tracking is to take advantage of
1532  // the assumption cache, so make sure that is populated.
1533  if (!CondVal->getType()->isVectorTy() && !AC.assumptions().empty()) {
1534  KnownBits Known(1);
1535  computeKnownBits(CondVal, Known, 0, &SI);
1536  if (Known.One.isOneValue())
1537  return replaceInstUsesWith(SI, TrueVal);
1538  if (Known.Zero.isOneValue())
1539  return replaceInstUsesWith(SI, FalseVal);
1540  }
1541 
1542  if (Instruction *BitCastSel = foldSelectCmpBitcasts(SI, Builder))
1543  return BitCastSel;
1544 
1545  return nullptr;
1546 }
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:550
uint64_t CallInst * C
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:1634
This class is the base class for the comparison instructions.
Definition: InstrTypes.h:850
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:1128
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
static APInt getAllOnesValue(unsigned numBits)
Get the all-ones value.
Definition: APInt.h:555
DiagnosticInfoOptimizationBase::Argument NV
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:1391
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
BinaryOps getOpcode() const
Definition: InstrTypes.h:523
Value * CreateICmpULT(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1558
Value * CreateXor(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1095
match_zero m_Zero()
Match an arbitrary zero/null constant.
Definition: PatternMatch.h:145
This class represents zero extension of integer types.
Value * CreateICmpSLT(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1570
bool slt(const APInt &RHS) const
Signed less than comparison.
Definition: APInt.h:1183
static Value * foldSelectICmpAndOr(const SelectInst &SI, 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...
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 than
Definition: InstrTypes.h:885
0 1 0 0 True if ordered and less than
Definition: InstrTypes.h:866
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:697
1 1 1 0 True if unordered or not equal
Definition: InstrTypes.h:876
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:1253
static bool isEquality(Predicate P)
Return true if this predicate is either EQ or NE.
This class represents a sign extension of integer types.
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:227
void reserve(size_type N)
Definition: SmallVector.h:380
bool sle(const APInt &RHS) const
Signed less or equal comparison.
Definition: APInt.h:1218
void copyIRFlags(const Value *V, bool IncludeWrapFlags=true)
Convenience method to copy supported exact, fast-math, and (optionally) wrapping flags from V to this...
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:1488
Signed maximum.
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:207
Value * CreateNot(Value *V, const Twine &Name="")
Definition: IRBuilder.h:1142
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
BinaryOp_match< LHS, RHS, Instruction::Xor > m_Xor(const LHS &L, const RHS &R)
Definition: PatternMatch.h:562
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:958
Absolute value.
bool isUnsigned() const
Determine if this instruction is using an unsigned comparison.
Definition: InstrTypes.h:1007
CastClass_match< OpTy, Instruction::Trunc > m_Trunc(const OpTy &Op)
Matches Trunc.
Definition: PatternMatch.h:888
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:197
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:664
static Constant * getSExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1556
Value * CreateAdd(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:889
static SelectPatternFlavor getInverseMinMaxSelectPattern(SelectPatternFlavor SPF)
not_match< LHS > m_Not(const LHS &L)
Definition: PatternMatch.h:961
bool isOne() const
This is just a convenience method to make client code smaller for a common case.
Definition: Constants.h:201
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1570
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:86
FastMathFlags getFastMathFlags() const
Convenience function for getting all the fast-math flags, which must be an operator which supports th...
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
CastClass_match< OpTy, Instruction::ZExt > m_ZExt(const OpTy &Op)
Matches ZExt.
Definition: PatternMatch.h:900
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)
class_match< ConstantInt > m_ConstantInt()
Match an arbitrary ConstantInt and ignore it.
Definition: PatternMatch.h:83
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:138
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:121
bool isMinusOne() const
This function will return true iff every bit in this constant is set to true.
Definition: Constants.h:209
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:203
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power of 2.
Definition: PatternMatch.h:306
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:290
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:154
void replaceUsesOfWith(Value *From, Value *To)
Replace uses of one Value with another.
Definition: User.cpp:22
SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, Instruction::CastOps *CastOp=nullptr)
Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind and providing the out param...
Value * CreateOr(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1079
Constant * getAggregateElement(unsigned Elt) const
For aggregates (struct/array/vector) return the constant that corresponds to the specified element if...
Definition: Constants.cpp:277
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:1641
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:63
bool hasNUsesOrMore(unsigned N) const
Return true if this value has N users or more.
Definition: Value.cpp:134
Value * SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, const SimplifyQuery &Q)
Given operands for a SelectInst, fold the result or return null.
MaxMin_match< ICmpInst, LHS, RHS, umax_pred_ty > m_UMax(const LHS &L, const RHS &R)
bool hasNUses(unsigned N) const
Return true if this Value has exactly N users.
Definition: Value.cpp:126
apint_match m_APInt(const APInt *&Res)
Match a ConstantInt or splatted ConstantVector, binding the specified pointer to the contained APInt...
Definition: PatternMatch.h:240
const BasicBlock * getSinglePredecessor() const
Return the predecessor of this block if it has a single predecessor block.
Definition: BasicBlock.cpp:217
Value * CreateAShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1045
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:556
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1164
CastClass_match< OpTy, Instruction::BitCast > m_BitCast(const OpTy &Op)
Matches BitCast.
Definition: PatternMatch.h:876
This is an important base class in LLVM.
Definition: Constant.h:42
Value * CreateSelect(Value *C, Value *True, Value *False, const Twine &Name="", Instruction *MDFrom=nullptr)
Definition: IRBuilder.h:1689
#define A
Definition: LargeTest.cpp:12
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
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:358
Value * CreateNeg(Value *V, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1120
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:860
static bool isNot(const Value *V)
Class to represent integer types.
Definition: DerivedTypes.h:40
const Value * getCondition() const
static Constant * getAllOnesValue(Type *Ty)
Get the all ones value.
Definition: Constants.cpp:261
bool isCast() const
Definition: Instruction.h:127
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:887
const APFloat & getValueAPF() const
Definition: Constants.h:294
CastClass_match< OpTy, Instruction::SExt > m_SExt(const OpTy &Op)
Matches SExt.
Definition: PatternMatch.h:894
Floating point maxnum.
0 0 1 0 True if ordered and greater than
Definition: InstrTypes.h:864
unsigned getNumOperands() const
Definition: User.h:176
This is the shared class of boolean and integer constants.
Definition: Constants.h:84
SelectPatternFlavor Flavor
#define B
Definition: LargeTest.cpp:24
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type...
Definition: Type.cpp:130
Unsigned maximum.
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:864
1 1 0 0 True if unordered or less than
Definition: InstrTypes.h:874
SelectPatternFlavor
Specific patterns of select instructions we can match.
Floating point minnum.
signed less than
Definition: InstrTypes.h:889
static Constant * getTrunc(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1542
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:560
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1272
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:516
bool isCommutative() const
Return true if the instruction is commutative:
Definition: Instruction.h:416
Instruction * visitSelectInst(SelectInst &SI)
void setPredicate(Predicate P)
Set the predicate for this instruction to the specified value.
Definition: InstrTypes.h:939
void setOperand(unsigned i, Value *Val)
Definition: User.h:159
unsigned logBase2() const
Definition: APInt.h:1727
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:923
unsigned getVectorNumElements() const
Definition: DerivedTypes.h:462
bool isIntPredicate() const
Definition: InstrTypes.h:952
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:1202
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 greather or equal comparison.
Definition: APInt.h:1288
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1435
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1008
const Value * getFalseValue() const
void setCondition(Value *V)
static std::vector< std::string > Flags
Definition: FlagsTest.cpp:8
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:1234
Predicate getPredicate() const
Return the predicate for this instruction.
Definition: InstrTypes.h:934
static cl::opt< bool > NeedAnd("extract-needand", cl::init(true), cl::Hidden, cl::desc("Require & in extract patterns"))
void setTrueValue(Value *V)
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:176
unsigned getIntegerBitWidth() const
Definition: DerivedTypes.h:97
static bool isMinOrMax(SelectPatternFlavor SPF)
When implementing this min/max pattern as fcmp; select, does the fcmp have to be ordered?
static bool isUnordered(Predicate predicate)
Determine if the predicate is an unordered operation.
match_one m_One()
Match an integer 1 or a vector with all elements equal to 1.
Definition: PatternMatch.h:194
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:218
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)
bool isZero() const
This is just a convenience method to make client code smaller for a common code.
Definition: Constants.h:193
static Value * generateMinMaxSelectPattern(InstCombiner::BuilderTy &Builder, SelectPatternFlavor SPF, Value *A, Value *B)
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)
static volatile int Zero
1 0 1 0 True if unordered or greater than
Definition: InstrTypes.h:872
Signed minimum.
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1063
static Constant * getSelectFoldableConstant(Instruction *I)
For the same transformation as the previous function, return the identity constant that goes into the...
InstTy * Insert(InstTy *I, const Twine &Name="") const
Insert and return the specified instruction.
Definition: IRBuilder.h:715
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:127
Value * CreateCast(Instruction::CastOps Op, Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1476
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
user_iterator user_begin()
Definition: Value.h:371
static APInt getSignedMinValue(unsigned numBits)
Gets minimum signed value of APInt for a specific bit width.
Definition: APInt.h:538
match_all_ones m_AllOnes()
Match an integer or vector with all bits set to true.
Definition: PatternMatch.h:205
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:115
0 0 0 1 True if ordered and equal
Definition: InstrTypes.h:863
LLVM Value Representation.
Definition: Value.h:73
static CmpInst::Predicate getCmpPredicateForMinMax(SelectPatternFlavor SPF, bool Ordered=false)
This file provides internal interfaces used to implement the InstCombine.
static unsigned getSelectFoldableOperands(Instruction *I)
We want to turn code that looks like this: C = or A, B D = select cond, C, A into: C = select cond...
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:221
void moveBefore(Instruction *MovePos)
Unlink this instruction from its current basic block and insert it into the basic block that MovePos ...
Definition: Instruction.cpp:88
static bool isSelect01(Constant *C1, Constant *C2)
Value * CreateLShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1027
Optional< bool > isImpliedCondition(const Value *LHS, const Value *RHS, const DataLayout &DL, bool LHSIsFalse=false, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr)
Return true if RHS is known to be implied true by LHS.
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:408
Convenience struct for specifying and reasoning about fast-math flags.
Definition: Operator.h:160
unsigned greater than
Definition: InstrTypes.h:883
Predicate getSwappedPredicate() const
For example, EQ->EQ, SLE->SGE, ULT->UGT, OEQ->OEQ, ULE->UGE, OLT->OGT, etc.
Definition: InstrTypes.h:974
specific_intval m_SpecificInt(uint64_t V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:419
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:984
#define D
Definition: LargeTest.cpp:26
Value * CreateFNeg(Value *V, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1135
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:335
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:66
CmpClass_match< LHS, RHS, ICmpInst, ICmpInst::Predicate > m_ICmp(ICmpInst::Predicate &Pred, const LHS &L, const RHS &R)
Definition: PatternMatch.h:813