LLVM  8.0.0svn
InstCombineShifts.cpp
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1 //===- InstCombineShifts.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 visitShl, visitLShr, and visitAShr functions.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "InstCombineInternal.h"
17 #include "llvm/IR/IntrinsicInst.h"
18 #include "llvm/IR/PatternMatch.h"
19 using namespace llvm;
20 using namespace PatternMatch;
21 
22 #define DEBUG_TYPE "instcombine"
23 
25  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
26  assert(Op0->getType() == Op1->getType());
27 
28  // See if we can fold away this shift.
29  if (SimplifyDemandedInstructionBits(I))
30  return &I;
31 
32  // Try to fold constant and into select arguments.
33  if (isa<Constant>(Op0))
34  if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
35  if (Instruction *R = FoldOpIntoSelect(I, SI))
36  return R;
37 
38  if (Constant *CUI = dyn_cast<Constant>(Op1))
39  if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
40  return Res;
41 
42  // (C1 shift (A add C2)) -> (C1 shift C2) shift A)
43  // iff A and C2 are both positive.
44  Value *A;
45  Constant *C;
46  if (match(Op0, m_Constant()) && match(Op1, m_Add(m_Value(A), m_Constant(C))))
47  if (isKnownNonNegative(A, DL, 0, &AC, &I, &DT) &&
48  isKnownNonNegative(C, DL, 0, &AC, &I, &DT))
50  I.getOpcode(), Builder.CreateBinOp(I.getOpcode(), Op0, C), A);
51 
52  // X shift (A srem B) -> X shift (A and B-1) iff B is a power of 2.
53  // Because shifts by negative values (which could occur if A were negative)
54  // are undefined.
55  const APInt *B;
56  if (Op1->hasOneUse() && match(Op1, m_SRem(m_Value(A), m_Power2(B)))) {
57  // FIXME: Should this get moved into SimplifyDemandedBits by saying we don't
58  // demand the sign bit (and many others) here??
59  Value *Rem = Builder.CreateAnd(A, ConstantInt::get(I.getType(), *B - 1),
60  Op1->getName());
61  I.setOperand(1, Rem);
62  return &I;
63  }
64 
65  return nullptr;
66 }
67 
68 /// Return true if we can simplify two logical (either left or right) shifts
69 /// that have constant shift amounts: OuterShift (InnerShift X, C1), C2.
70 static bool canEvaluateShiftedShift(unsigned OuterShAmt, bool IsOuterShl,
71  Instruction *InnerShift, InstCombiner &IC,
72  Instruction *CxtI) {
73  assert(InnerShift->isLogicalShift() && "Unexpected instruction type");
74 
75  // We need constant scalar or constant splat shifts.
76  const APInt *InnerShiftConst;
77  if (!match(InnerShift->getOperand(1), m_APInt(InnerShiftConst)))
78  return false;
79 
80  // Two logical shifts in the same direction:
81  // shl (shl X, C1), C2 --> shl X, C1 + C2
82  // lshr (lshr X, C1), C2 --> lshr X, C1 + C2
83  bool IsInnerShl = InnerShift->getOpcode() == Instruction::Shl;
84  if (IsInnerShl == IsOuterShl)
85  return true;
86 
87  // Equal shift amounts in opposite directions become bitwise 'and':
88  // lshr (shl X, C), C --> and X, C'
89  // shl (lshr X, C), C --> and X, C'
90  if (*InnerShiftConst == OuterShAmt)
91  return true;
92 
93  // If the 2nd shift is bigger than the 1st, we can fold:
94  // lshr (shl X, C1), C2 --> and (shl X, C1 - C2), C3
95  // shl (lshr X, C1), C2 --> and (lshr X, C1 - C2), C3
96  // but it isn't profitable unless we know the and'd out bits are already zero.
97  // Also, check that the inner shift is valid (less than the type width) or
98  // we'll crash trying to produce the bit mask for the 'and'.
99  unsigned TypeWidth = InnerShift->getType()->getScalarSizeInBits();
100  if (InnerShiftConst->ugt(OuterShAmt) && InnerShiftConst->ult(TypeWidth)) {
101  unsigned InnerShAmt = InnerShiftConst->getZExtValue();
102  unsigned MaskShift =
103  IsInnerShl ? TypeWidth - InnerShAmt : InnerShAmt - OuterShAmt;
104  APInt Mask = APInt::getLowBitsSet(TypeWidth, OuterShAmt) << MaskShift;
105  if (IC.MaskedValueIsZero(InnerShift->getOperand(0), Mask, 0, CxtI))
106  return true;
107  }
108 
109  return false;
110 }
111 
112 /// See if we can compute the specified value, but shifted logically to the left
113 /// or right by some number of bits. This should return true if the expression
114 /// can be computed for the same cost as the current expression tree. This is
115 /// used to eliminate extraneous shifting from things like:
116 /// %C = shl i128 %A, 64
117 /// %D = shl i128 %B, 96
118 /// %E = or i128 %C, %D
119 /// %F = lshr i128 %E, 64
120 /// where the client will ask if E can be computed shifted right by 64-bits. If
121 /// this succeeds, getShiftedValue() will be called to produce the value.
122 static bool canEvaluateShifted(Value *V, unsigned NumBits, bool IsLeftShift,
123  InstCombiner &IC, Instruction *CxtI) {
124  // We can always evaluate constants shifted.
125  if (isa<Constant>(V))
126  return true;
127 
129  if (!I) return false;
130 
131  // If this is the opposite shift, we can directly reuse the input of the shift
132  // if the needed bits are already zero in the input. This allows us to reuse
133  // the value which means that we don't care if the shift has multiple uses.
134  // TODO: Handle opposite shift by exact value.
135  ConstantInt *CI = nullptr;
136  if ((IsLeftShift && match(I, m_LShr(m_Value(), m_ConstantInt(CI)))) ||
137  (!IsLeftShift && match(I, m_Shl(m_Value(), m_ConstantInt(CI))))) {
138  if (CI->getValue() == NumBits) {
139  // TODO: Check that the input bits are already zero with MaskedValueIsZero
140 #if 0
141  // If this is a truncate of a logical shr, we can truncate it to a smaller
142  // lshr iff we know that the bits we would otherwise be shifting in are
143  // already zeros.
144  uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
145  uint32_t BitWidth = Ty->getScalarSizeInBits();
146  if (MaskedValueIsZero(I->getOperand(0),
147  APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
148  CI->getLimitedValue(BitWidth) < BitWidth) {
149  return CanEvaluateTruncated(I->getOperand(0), Ty);
150  }
151 #endif
152 
153  }
154  }
155 
156  // We can't mutate something that has multiple uses: doing so would
157  // require duplicating the instruction in general, which isn't profitable.
158  if (!I->hasOneUse()) return false;
159 
160  switch (I->getOpcode()) {
161  default: return false;
162  case Instruction::And:
163  case Instruction::Or:
164  case Instruction::Xor:
165  // Bitwise operators can all arbitrarily be arbitrarily evaluated shifted.
166  return canEvaluateShifted(I->getOperand(0), NumBits, IsLeftShift, IC, I) &&
167  canEvaluateShifted(I->getOperand(1), NumBits, IsLeftShift, IC, I);
168 
169  case Instruction::Shl:
170  case Instruction::LShr:
171  return canEvaluateShiftedShift(NumBits, IsLeftShift, I, IC, CxtI);
172 
173  case Instruction::Select: {
174  SelectInst *SI = cast<SelectInst>(I);
175  Value *TrueVal = SI->getTrueValue();
176  Value *FalseVal = SI->getFalseValue();
177  return canEvaluateShifted(TrueVal, NumBits, IsLeftShift, IC, SI) &&
178  canEvaluateShifted(FalseVal, NumBits, IsLeftShift, IC, SI);
179  }
180  case Instruction::PHI: {
181  // We can change a phi if we can change all operands. Note that we never
182  // get into trouble with cyclic PHIs here because we only consider
183  // instructions with a single use.
184  PHINode *PN = cast<PHINode>(I);
185  for (Value *IncValue : PN->incoming_values())
186  if (!canEvaluateShifted(IncValue, NumBits, IsLeftShift, IC, PN))
187  return false;
188  return true;
189  }
190  }
191 }
192 
193 /// Fold OuterShift (InnerShift X, C1), C2.
194 /// See canEvaluateShiftedShift() for the constraints on these instructions.
195 static Value *foldShiftedShift(BinaryOperator *InnerShift, unsigned OuterShAmt,
196  bool IsOuterShl,
197  InstCombiner::BuilderTy &Builder) {
198  bool IsInnerShl = InnerShift->getOpcode() == Instruction::Shl;
199  Type *ShType = InnerShift->getType();
200  unsigned TypeWidth = ShType->getScalarSizeInBits();
201 
202  // We only accept shifts-by-a-constant in canEvaluateShifted().
203  const APInt *C1;
204  match(InnerShift->getOperand(1), m_APInt(C1));
205  unsigned InnerShAmt = C1->getZExtValue();
206 
207  // Change the shift amount and clear the appropriate IR flags.
208  auto NewInnerShift = [&](unsigned ShAmt) {
209  InnerShift->setOperand(1, ConstantInt::get(ShType, ShAmt));
210  if (IsInnerShl) {
211  InnerShift->setHasNoUnsignedWrap(false);
212  InnerShift->setHasNoSignedWrap(false);
213  } else {
214  InnerShift->setIsExact(false);
215  }
216  return InnerShift;
217  };
218 
219  // Two logical shifts in the same direction:
220  // shl (shl X, C1), C2 --> shl X, C1 + C2
221  // lshr (lshr X, C1), C2 --> lshr X, C1 + C2
222  if (IsInnerShl == IsOuterShl) {
223  // If this is an oversized composite shift, then unsigned shifts get 0.
224  if (InnerShAmt + OuterShAmt >= TypeWidth)
225  return Constant::getNullValue(ShType);
226 
227  return NewInnerShift(InnerShAmt + OuterShAmt);
228  }
229 
230  // Equal shift amounts in opposite directions become bitwise 'and':
231  // lshr (shl X, C), C --> and X, C'
232  // shl (lshr X, C), C --> and X, C'
233  if (InnerShAmt == OuterShAmt) {
234  APInt Mask = IsInnerShl
235  ? APInt::getLowBitsSet(TypeWidth, TypeWidth - OuterShAmt)
236  : APInt::getHighBitsSet(TypeWidth, TypeWidth - OuterShAmt);
237  Value *And = Builder.CreateAnd(InnerShift->getOperand(0),
238  ConstantInt::get(ShType, Mask));
239  if (auto *AndI = dyn_cast<Instruction>(And)) {
240  AndI->moveBefore(InnerShift);
241  AndI->takeName(InnerShift);
242  }
243  return And;
244  }
245 
246  assert(InnerShAmt > OuterShAmt &&
247  "Unexpected opposite direction logical shift pair");
248 
249  // In general, we would need an 'and' for this transform, but
250  // canEvaluateShiftedShift() guarantees that the masked-off bits are not used.
251  // lshr (shl X, C1), C2 --> shl X, C1 - C2
252  // shl (lshr X, C1), C2 --> lshr X, C1 - C2
253  return NewInnerShift(InnerShAmt - OuterShAmt);
254 }
255 
256 /// When canEvaluateShifted() returns true for an expression, this function
257 /// inserts the new computation that produces the shifted value.
258 static Value *getShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
259  InstCombiner &IC, const DataLayout &DL) {
260  // We can always evaluate constants shifted.
261  if (Constant *C = dyn_cast<Constant>(V)) {
262  if (isLeftShift)
263  V = IC.Builder.CreateShl(C, NumBits);
264  else
265  V = IC.Builder.CreateLShr(C, NumBits);
266  // If we got a constantexpr back, try to simplify it with TD info.
267  if (auto *C = dyn_cast<Constant>(V))
268  if (auto *FoldedC =
270  V = FoldedC;
271  return V;
272  }
273 
274  Instruction *I = cast<Instruction>(V);
275  IC.Worklist.Add(I);
276 
277  switch (I->getOpcode()) {
278  default: llvm_unreachable("Inconsistency with CanEvaluateShifted");
279  case Instruction::And:
280  case Instruction::Or:
281  case Instruction::Xor:
282  // Bitwise operators can all arbitrarily be arbitrarily evaluated shifted.
283  I->setOperand(
284  0, getShiftedValue(I->getOperand(0), NumBits, isLeftShift, IC, DL));
285  I->setOperand(
286  1, getShiftedValue(I->getOperand(1), NumBits, isLeftShift, IC, DL));
287  return I;
288 
289  case Instruction::Shl:
290  case Instruction::LShr:
291  return foldShiftedShift(cast<BinaryOperator>(I), NumBits, isLeftShift,
292  IC.Builder);
293 
294  case Instruction::Select:
295  I->setOperand(
296  1, getShiftedValue(I->getOperand(1), NumBits, isLeftShift, IC, DL));
297  I->setOperand(
298  2, getShiftedValue(I->getOperand(2), NumBits, isLeftShift, IC, DL));
299  return I;
300  case Instruction::PHI: {
301  // We can change a phi if we can change all operands. Note that we never
302  // get into trouble with cyclic PHIs here because we only consider
303  // instructions with a single use.
304  PHINode *PN = cast<PHINode>(I);
305  for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
306  PN->setIncomingValue(i, getShiftedValue(PN->getIncomingValue(i), NumBits,
307  isLeftShift, IC, DL));
308  return PN;
309  }
310  }
311 }
312 
313 // If this is a bitwise operator or add with a constant RHS we might be able
314 // to pull it through a shift.
316  BinaryOperator *BO,
317  const APInt &C) {
318  bool IsValid = true; // Valid only for And, Or Xor,
319  bool HighBitSet = false; // Transform ifhigh bit of constant set?
320 
321  switch (BO->getOpcode()) {
322  default: IsValid = false; break; // Do not perform transform!
323  case Instruction::Add:
324  IsValid = Shift.getOpcode() == Instruction::Shl;
325  break;
326  case Instruction::Or:
327  case Instruction::Xor:
328  HighBitSet = false;
329  break;
330  case Instruction::And:
331  HighBitSet = true;
332  break;
333  }
334 
335  // If this is a signed shift right, and the high bit is modified
336  // by the logical operation, do not perform the transformation.
337  // The HighBitSet boolean indicates the value of the high bit of
338  // the constant which would cause it to be modified for this
339  // operation.
340  //
341  if (IsValid && Shift.getOpcode() == Instruction::AShr)
342  IsValid = C.isNegative() == HighBitSet;
343 
344  return IsValid;
345 }
346 
348  BinaryOperator &I) {
349  bool isLeftShift = I.getOpcode() == Instruction::Shl;
350 
351  const APInt *Op1C;
352  if (!match(Op1, m_APInt(Op1C)))
353  return nullptr;
354 
355  // See if we can propagate this shift into the input, this covers the trivial
356  // cast of lshr(shl(x,c1),c2) as well as other more complex cases.
357  if (I.getOpcode() != Instruction::AShr &&
358  canEvaluateShifted(Op0, Op1C->getZExtValue(), isLeftShift, *this, &I)) {
359  LLVM_DEBUG(
360  dbgs() << "ICE: GetShiftedValue propagating shift through expression"
361  " to eliminate shift:\n IN: "
362  << *Op0 << "\n SH: " << I << "\n");
363 
364  return replaceInstUsesWith(
365  I, getShiftedValue(Op0, Op1C->getZExtValue(), isLeftShift, *this, DL));
366  }
367 
368  // See if we can simplify any instructions used by the instruction whose sole
369  // purpose is to compute bits we don't care about.
370  unsigned TypeBits = Op0->getType()->getScalarSizeInBits();
371 
372  assert(!Op1C->uge(TypeBits) &&
373  "Shift over the type width should have been removed already");
374 
375  if (Instruction *FoldedShift = foldBinOpIntoSelectOrPhi(I))
376  return FoldedShift;
377 
378  // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
379  if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
380  Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
381  // If 'shift2' is an ashr, we would have to get the sign bit into a funny
382  // place. Don't try to do this transformation in this case. Also, we
383  // require that the input operand is a shift-by-constant so that we have
384  // confidence that the shifts will get folded together. We could do this
385  // xform in more cases, but it is unlikely to be profitable.
386  if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
387  isa<ConstantInt>(TrOp->getOperand(1))) {
388  // Okay, we'll do this xform. Make the shift of shift.
389  Constant *ShAmt =
390  ConstantExpr::getZExt(cast<Constant>(Op1), TrOp->getType());
391  // (shift2 (shift1 & 0x00FF), c2)
392  Value *NSh = Builder.CreateBinOp(I.getOpcode(), TrOp, ShAmt, I.getName());
393 
394  // For logical shifts, the truncation has the effect of making the high
395  // part of the register be zeros. Emulate this by inserting an AND to
396  // clear the top bits as needed. This 'and' will usually be zapped by
397  // other xforms later if dead.
398  unsigned SrcSize = TrOp->getType()->getScalarSizeInBits();
399  unsigned DstSize = TI->getType()->getScalarSizeInBits();
400  APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
401 
402  // The mask we constructed says what the trunc would do if occurring
403  // between the shifts. We want to know the effect *after* the second
404  // shift. We know that it is a logical shift by a constant, so adjust the
405  // mask as appropriate.
406  if (I.getOpcode() == Instruction::Shl)
407  MaskV <<= Op1C->getZExtValue();
408  else {
409  assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
410  MaskV.lshrInPlace(Op1C->getZExtValue());
411  }
412 
413  // shift1 & 0x00FF
414  Value *And = Builder.CreateAnd(NSh,
415  ConstantInt::get(I.getContext(), MaskV),
416  TI->getName());
417 
418  // Return the value truncated to the interesting size.
419  return new TruncInst(And, I.getType());
420  }
421  }
422 
423  if (Op0->hasOneUse()) {
424  if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
425  // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
426  Value *V1, *V2;
427  ConstantInt *CC;
428  switch (Op0BO->getOpcode()) {
429  default: break;
430  case Instruction::Add:
431  case Instruction::And:
432  case Instruction::Or:
433  case Instruction::Xor: {
434  // These operators commute.
435  // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
436  if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
437  match(Op0BO->getOperand(1), m_Shr(m_Value(V1),
438  m_Specific(Op1)))) {
439  Value *YS = // (Y << C)
440  Builder.CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
441  // (X + (Y << C))
442  Value *X = Builder.CreateBinOp(Op0BO->getOpcode(), YS, V1,
443  Op0BO->getOperand(1)->getName());
444  unsigned Op1Val = Op1C->getLimitedValue(TypeBits);
445 
446  APInt Bits = APInt::getHighBitsSet(TypeBits, TypeBits - Op1Val);
448  if (VectorType *VT = dyn_cast<VectorType>(X->getType()))
449  Mask = ConstantVector::getSplat(VT->getNumElements(), Mask);
450  return BinaryOperator::CreateAnd(X, Mask);
451  }
452 
453  // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
454  Value *Op0BOOp1 = Op0BO->getOperand(1);
455  if (isLeftShift && Op0BOOp1->hasOneUse() &&
456  match(Op0BOOp1,
457  m_And(m_OneUse(m_Shr(m_Value(V1), m_Specific(Op1))),
458  m_ConstantInt(CC)))) {
459  Value *YS = // (Y << C)
460  Builder.CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
461  // X & (CC << C)
462  Value *XM = Builder.CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
463  V1->getName()+".mask");
464  return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
465  }
467  }
468 
469  case Instruction::Sub: {
470  // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
471  if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
472  match(Op0BO->getOperand(0), m_Shr(m_Value(V1),
473  m_Specific(Op1)))) {
474  Value *YS = // (Y << C)
475  Builder.CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
476  // (X + (Y << C))
477  Value *X = Builder.CreateBinOp(Op0BO->getOpcode(), V1, YS,
478  Op0BO->getOperand(0)->getName());
479  unsigned Op1Val = Op1C->getLimitedValue(TypeBits);
480 
481  APInt Bits = APInt::getHighBitsSet(TypeBits, TypeBits - Op1Val);
483  if (VectorType *VT = dyn_cast<VectorType>(X->getType()))
484  Mask = ConstantVector::getSplat(VT->getNumElements(), Mask);
485  return BinaryOperator::CreateAnd(X, Mask);
486  }
487 
488  // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
489  if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
490  match(Op0BO->getOperand(0),
491  m_And(m_OneUse(m_Shr(m_Value(V1), m_Value(V2))),
492  m_ConstantInt(CC))) && V2 == Op1) {
493  Value *YS = // (Y << C)
494  Builder.CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
495  // X & (CC << C)
496  Value *XM = Builder.CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
497  V1->getName()+".mask");
498 
499  return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
500  }
501 
502  break;
503  }
504  }
505 
506 
507  // If the operand is a bitwise operator with a constant RHS, and the
508  // shift is the only use, we can pull it out of the shift.
509  const APInt *Op0C;
510  if (match(Op0BO->getOperand(1), m_APInt(Op0C))) {
511  if (canShiftBinOpWithConstantRHS(I, Op0BO, *Op0C)) {
512  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
513  cast<Constant>(Op0BO->getOperand(1)), Op1);
514 
515  Value *NewShift =
516  Builder.CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1);
517  NewShift->takeName(Op0BO);
518 
519  return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
520  NewRHS);
521  }
522  }
523 
524  // If the operand is a subtract with a constant LHS, and the shift
525  // is the only use, we can pull it out of the shift.
526  // This folds (shl (sub C1, X), C2) -> (sub (C1 << C2), (shl X, C2))
527  if (isLeftShift && Op0BO->getOpcode() == Instruction::Sub &&
528  match(Op0BO->getOperand(0), m_APInt(Op0C))) {
529  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
530  cast<Constant>(Op0BO->getOperand(0)), Op1);
531 
532  Value *NewShift = Builder.CreateShl(Op0BO->getOperand(1), Op1);
533  NewShift->takeName(Op0BO);
534 
535  return BinaryOperator::CreateSub(NewRHS, NewShift);
536  }
537  }
538 
539  // If we have a select that conditionally executes some binary operator,
540  // see if we can pull it the select and operator through the shift.
541  //
542  // For example, turning:
543  // shl (select C, (add X, C1), X), C2
544  // Into:
545  // Y = shl X, C2
546  // select C, (add Y, C1 << C2), Y
547  Value *Cond;
548  BinaryOperator *TBO;
549  Value *FalseVal;
550  if (match(Op0, m_Select(m_Value(Cond), m_OneUse(m_BinOp(TBO)),
551  m_Value(FalseVal)))) {
552  const APInt *C;
553  if (!isa<Constant>(FalseVal) && TBO->getOperand(0) == FalseVal &&
554  match(TBO->getOperand(1), m_APInt(C)) &&
555  canShiftBinOpWithConstantRHS(I, TBO, *C)) {
556  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
557  cast<Constant>(TBO->getOperand(1)), Op1);
558 
559  Value *NewShift =
560  Builder.CreateBinOp(I.getOpcode(), FalseVal, Op1);
561  Value *NewOp = Builder.CreateBinOp(TBO->getOpcode(), NewShift,
562  NewRHS);
563  return SelectInst::Create(Cond, NewOp, NewShift);
564  }
565  }
566 
567  BinaryOperator *FBO;
568  Value *TrueVal;
569  if (match(Op0, m_Select(m_Value(Cond), m_Value(TrueVal),
570  m_OneUse(m_BinOp(FBO))))) {
571  const APInt *C;
572  if (!isa<Constant>(TrueVal) && FBO->getOperand(0) == TrueVal &&
573  match(FBO->getOperand(1), m_APInt(C)) &&
574  canShiftBinOpWithConstantRHS(I, FBO, *C)) {
575  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
576  cast<Constant>(FBO->getOperand(1)), Op1);
577 
578  Value *NewShift =
579  Builder.CreateBinOp(I.getOpcode(), TrueVal, Op1);
580  Value *NewOp = Builder.CreateBinOp(FBO->getOpcode(), NewShift,
581  NewRHS);
582  return SelectInst::Create(Cond, NewShift, NewOp);
583  }
584  }
585  }
586 
587  return nullptr;
588 }
589 
591  if (Value *V = SimplifyShlInst(I.getOperand(0), I.getOperand(1),
593  SQ.getWithInstruction(&I)))
594  return replaceInstUsesWith(I, V);
595 
596  if (Instruction *X = foldVectorBinop(I))
597  return X;
598 
599  if (Instruction *V = commonShiftTransforms(I))
600  return V;
601 
602  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
603  Type *Ty = I.getType();
604  const APInt *ShAmtAPInt;
605  if (match(Op1, m_APInt(ShAmtAPInt))) {
606  unsigned ShAmt = ShAmtAPInt->getZExtValue();
607  unsigned BitWidth = Ty->getScalarSizeInBits();
608 
609  // shl (zext X), ShAmt --> zext (shl X, ShAmt)
610  // This is only valid if X would have zeros shifted out.
611  Value *X;
612  if (match(Op0, m_ZExt(m_Value(X)))) {
613  unsigned SrcWidth = X->getType()->getScalarSizeInBits();
614  if (ShAmt < SrcWidth &&
615  MaskedValueIsZero(X, APInt::getHighBitsSet(SrcWidth, ShAmt), 0, &I))
616  return new ZExtInst(Builder.CreateShl(X, ShAmt), Ty);
617  }
618 
619  // (X >> C) << C --> X & (-1 << C)
620  if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1)))) {
621  APInt Mask(APInt::getHighBitsSet(BitWidth, BitWidth - ShAmt));
622  return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, Mask));
623  }
624 
625  // FIXME: we do not yet transform non-exact shr's. The backend (DAGCombine)
626  // needs a few fixes for the rotate pattern recognition first.
627  const APInt *ShOp1;
628  if (match(Op0, m_Exact(m_Shr(m_Value(X), m_APInt(ShOp1))))) {
629  unsigned ShrAmt = ShOp1->getZExtValue();
630  if (ShrAmt < ShAmt) {
631  // If C1 < C2: (X >>?,exact C1) << C2 --> X << (C2 - C1)
632  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShrAmt);
633  auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
634  NewShl->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
635  NewShl->setHasNoSignedWrap(I.hasNoSignedWrap());
636  return NewShl;
637  }
638  if (ShrAmt > ShAmt) {
639  // If C1 > C2: (X >>?exact C1) << C2 --> X >>?exact (C1 - C2)
640  Constant *ShiftDiff = ConstantInt::get(Ty, ShrAmt - ShAmt);
641  auto *NewShr = BinaryOperator::Create(
642  cast<BinaryOperator>(Op0)->getOpcode(), X, ShiftDiff);
643  NewShr->setIsExact(true);
644  return NewShr;
645  }
646  }
647 
648  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShOp1)))) {
649  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
650  // Oversized shifts are simplified to zero in InstSimplify.
651  if (AmtSum < BitWidth)
652  // (X << C1) << C2 --> X << (C1 + C2)
653  return BinaryOperator::CreateShl(X, ConstantInt::get(Ty, AmtSum));
654  }
655 
656  // If the shifted-out value is known-zero, then this is a NUW shift.
657  if (!I.hasNoUnsignedWrap() &&
658  MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, ShAmt), 0, &I)) {
660  return &I;
661  }
662 
663  // If the shifted-out value is all signbits, then this is a NSW shift.
664  if (!I.hasNoSignedWrap() && ComputeNumSignBits(Op0, 0, &I) > ShAmt) {
665  I.setHasNoSignedWrap();
666  return &I;
667  }
668  }
669 
670  // Transform (x >> y) << y to x & (-1 << y)
671  // Valid for any type of right-shift.
672  Value *X;
673  if (match(Op0, m_OneUse(m_Shr(m_Value(X), m_Specific(Op1))))) {
674  Constant *AllOnes = ConstantInt::getAllOnesValue(Ty);
675  Value *Mask = Builder.CreateShl(AllOnes, Op1);
676  return BinaryOperator::CreateAnd(Mask, X);
677  }
678 
679  Constant *C1;
680  if (match(Op1, m_Constant(C1))) {
681  Constant *C2;
682  Value *X;
683  // (C2 << X) << C1 --> (C2 << C1) << X
684  if (match(Op0, m_OneUse(m_Shl(m_Constant(C2), m_Value(X)))))
685  return BinaryOperator::CreateShl(ConstantExpr::getShl(C2, C1), X);
686 
687  // (X * C2) << C1 --> X * (C2 << C1)
688  if (match(Op0, m_Mul(m_Value(X), m_Constant(C2))))
690  }
691 
692  return nullptr;
693 }
694 
696  if (Value *V = SimplifyLShrInst(I.getOperand(0), I.getOperand(1), I.isExact(),
697  SQ.getWithInstruction(&I)))
698  return replaceInstUsesWith(I, V);
699 
700  if (Instruction *X = foldVectorBinop(I))
701  return X;
702 
703  if (Instruction *R = commonShiftTransforms(I))
704  return R;
705 
706  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
707  Type *Ty = I.getType();
708  const APInt *ShAmtAPInt;
709  if (match(Op1, m_APInt(ShAmtAPInt))) {
710  unsigned ShAmt = ShAmtAPInt->getZExtValue();
711  unsigned BitWidth = Ty->getScalarSizeInBits();
712  auto *II = dyn_cast<IntrinsicInst>(Op0);
713  if (II && isPowerOf2_32(BitWidth) && Log2_32(BitWidth) == ShAmt &&
714  (II->getIntrinsicID() == Intrinsic::ctlz ||
715  II->getIntrinsicID() == Intrinsic::cttz ||
716  II->getIntrinsicID() == Intrinsic::ctpop)) {
717  // ctlz.i32(x)>>5 --> zext(x == 0)
718  // cttz.i32(x)>>5 --> zext(x == 0)
719  // ctpop.i32(x)>>5 --> zext(x == -1)
720  bool IsPop = II->getIntrinsicID() == Intrinsic::ctpop;
721  Constant *RHS = ConstantInt::getSigned(Ty, IsPop ? -1 : 0);
722  Value *Cmp = Builder.CreateICmpEQ(II->getArgOperand(0), RHS);
723  return new ZExtInst(Cmp, Ty);
724  }
725 
726  Value *X;
727  const APInt *ShOp1;
728  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShOp1))) && ShOp1->ult(BitWidth)) {
729  if (ShOp1->ult(ShAmt)) {
730  unsigned ShlAmt = ShOp1->getZExtValue();
731  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShlAmt);
732  if (cast<BinaryOperator>(Op0)->hasNoUnsignedWrap()) {
733  // (X <<nuw C1) >>u C2 --> X >>u (C2 - C1)
734  auto *NewLShr = BinaryOperator::CreateLShr(X, ShiftDiff);
735  NewLShr->setIsExact(I.isExact());
736  return NewLShr;
737  }
738  // (X << C1) >>u C2 --> (X >>u (C2 - C1)) & (-1 >> C2)
739  Value *NewLShr = Builder.CreateLShr(X, ShiftDiff, "", I.isExact());
740  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
741  return BinaryOperator::CreateAnd(NewLShr, ConstantInt::get(Ty, Mask));
742  }
743  if (ShOp1->ugt(ShAmt)) {
744  unsigned ShlAmt = ShOp1->getZExtValue();
745  Constant *ShiftDiff = ConstantInt::get(Ty, ShlAmt - ShAmt);
746  if (cast<BinaryOperator>(Op0)->hasNoUnsignedWrap()) {
747  // (X <<nuw C1) >>u C2 --> X <<nuw (C1 - C2)
748  auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
749  NewShl->setHasNoUnsignedWrap(true);
750  return NewShl;
751  }
752  // (X << C1) >>u C2 --> X << (C1 - C2) & (-1 >> C2)
753  Value *NewShl = Builder.CreateShl(X, ShiftDiff);
754  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
755  return BinaryOperator::CreateAnd(NewShl, ConstantInt::get(Ty, Mask));
756  }
757  assert(*ShOp1 == ShAmt);
758  // (X << C) >>u C --> X & (-1 >>u C)
759  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
760  return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, Mask));
761  }
762 
763  if (match(Op0, m_OneUse(m_ZExt(m_Value(X)))) &&
764  (!Ty->isIntegerTy() || shouldChangeType(Ty, X->getType()))) {
765  assert(ShAmt < X->getType()->getScalarSizeInBits() &&
766  "Big shift not simplified to zero?");
767  // lshr (zext iM X to iN), C --> zext (lshr X, C) to iN
768  Value *NewLShr = Builder.CreateLShr(X, ShAmt);
769  return new ZExtInst(NewLShr, Ty);
770  }
771 
772  if (match(Op0, m_SExt(m_Value(X))) &&
773  (!Ty->isIntegerTy() || shouldChangeType(Ty, X->getType()))) {
774  // Are we moving the sign bit to the low bit and widening with high zeros?
775  unsigned SrcTyBitWidth = X->getType()->getScalarSizeInBits();
776  if (ShAmt == BitWidth - 1) {
777  // lshr (sext i1 X to iN), N-1 --> zext X to iN
778  if (SrcTyBitWidth == 1)
779  return new ZExtInst(X, Ty);
780 
781  // lshr (sext iM X to iN), N-1 --> zext (lshr X, M-1) to iN
782  if (Op0->hasOneUse()) {
783  Value *NewLShr = Builder.CreateLShr(X, SrcTyBitWidth - 1);
784  return new ZExtInst(NewLShr, Ty);
785  }
786  }
787 
788  // lshr (sext iM X to iN), N-M --> zext (ashr X, min(N-M, M-1)) to iN
789  if (ShAmt == BitWidth - SrcTyBitWidth && Op0->hasOneUse()) {
790  // The new shift amount can't be more than the narrow source type.
791  unsigned NewShAmt = std::min(ShAmt, SrcTyBitWidth - 1);
792  Value *AShr = Builder.CreateAShr(X, NewShAmt);
793  return new ZExtInst(AShr, Ty);
794  }
795  }
796 
797  if (match(Op0, m_LShr(m_Value(X), m_APInt(ShOp1)))) {
798  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
799  // Oversized shifts are simplified to zero in InstSimplify.
800  if (AmtSum < BitWidth)
801  // (X >>u C1) >>u C2 --> X >>u (C1 + C2)
802  return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
803  }
804 
805  // If the shifted-out value is known-zero, then this is an exact shift.
806  if (!I.isExact() &&
807  MaskedValueIsZero(Op0, APInt::getLowBitsSet(BitWidth, ShAmt), 0, &I)) {
808  I.setIsExact();
809  return &I;
810  }
811  }
812 
813  // Transform (x << y) >> y to x & (-1 >> y)
814  Value *X;
815  if (match(Op0, m_OneUse(m_Shl(m_Value(X), m_Specific(Op1))))) {
816  Constant *AllOnes = ConstantInt::getAllOnesValue(Ty);
817  Value *Mask = Builder.CreateLShr(AllOnes, Op1);
818  return BinaryOperator::CreateAnd(Mask, X);
819  }
820 
821  return nullptr;
822 }
823 
825  if (Value *V = SimplifyAShrInst(I.getOperand(0), I.getOperand(1), I.isExact(),
826  SQ.getWithInstruction(&I)))
827  return replaceInstUsesWith(I, V);
828 
829  if (Instruction *X = foldVectorBinop(I))
830  return X;
831 
832  if (Instruction *R = commonShiftTransforms(I))
833  return R;
834 
835  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
836  Type *Ty = I.getType();
837  unsigned BitWidth = Ty->getScalarSizeInBits();
838  const APInt *ShAmtAPInt;
839  if (match(Op1, m_APInt(ShAmtAPInt)) && ShAmtAPInt->ult(BitWidth)) {
840  unsigned ShAmt = ShAmtAPInt->getZExtValue();
841 
842  // If the shift amount equals the difference in width of the destination
843  // and source scalar types:
844  // ashr (shl (zext X), C), C --> sext X
845  Value *X;
846  if (match(Op0, m_Shl(m_ZExt(m_Value(X)), m_Specific(Op1))) &&
847  ShAmt == BitWidth - X->getType()->getScalarSizeInBits())
848  return new SExtInst(X, Ty);
849 
850  // We can't handle (X << C1) >>s C2. It shifts arbitrary bits in. However,
851  // we can handle (X <<nsw C1) >>s C2 since it only shifts in sign bits.
852  const APInt *ShOp1;
853  if (match(Op0, m_NSWShl(m_Value(X), m_APInt(ShOp1))) &&
854  ShOp1->ult(BitWidth)) {
855  unsigned ShlAmt = ShOp1->getZExtValue();
856  if (ShlAmt < ShAmt) {
857  // (X <<nsw C1) >>s C2 --> X >>s (C2 - C1)
858  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShlAmt);
859  auto *NewAShr = BinaryOperator::CreateAShr(X, ShiftDiff);
860  NewAShr->setIsExact(I.isExact());
861  return NewAShr;
862  }
863  if (ShlAmt > ShAmt) {
864  // (X <<nsw C1) >>s C2 --> X <<nsw (C1 - C2)
865  Constant *ShiftDiff = ConstantInt::get(Ty, ShlAmt - ShAmt);
866  auto *NewShl = BinaryOperator::Create(Instruction::Shl, X, ShiftDiff);
867  NewShl->setHasNoSignedWrap(true);
868  return NewShl;
869  }
870  }
871 
872  if (match(Op0, m_AShr(m_Value(X), m_APInt(ShOp1))) &&
873  ShOp1->ult(BitWidth)) {
874  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
875  // Oversized arithmetic shifts replicate the sign bit.
876  AmtSum = std::min(AmtSum, BitWidth - 1);
877  // (X >>s C1) >>s C2 --> X >>s (C1 + C2)
878  return BinaryOperator::CreateAShr(X, ConstantInt::get(Ty, AmtSum));
879  }
880 
881  if (match(Op0, m_OneUse(m_SExt(m_Value(X)))) &&
882  (Ty->isVectorTy() || shouldChangeType(Ty, X->getType()))) {
883  // ashr (sext X), C --> sext (ashr X, C')
884  Type *SrcTy = X->getType();
885  ShAmt = std::min(ShAmt, SrcTy->getScalarSizeInBits() - 1);
886  Value *NewSh = Builder.CreateAShr(X, ConstantInt::get(SrcTy, ShAmt));
887  return new SExtInst(NewSh, Ty);
888  }
889 
890  // If the shifted-out value is known-zero, then this is an exact shift.
891  if (!I.isExact() &&
892  MaskedValueIsZero(Op0, APInt::getLowBitsSet(BitWidth, ShAmt), 0, &I)) {
893  I.setIsExact();
894  return &I;
895  }
896  }
897 
898  // See if we can turn a signed shr into an unsigned shr.
899  if (MaskedValueIsZero(Op0, APInt::getSignMask(BitWidth), 0, &I))
900  return BinaryOperator::CreateLShr(Op0, Op1);
901 
902  return nullptr;
903 }
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:750
uint64_t CallInst * C
BinOpPred_match< LHS, RHS, is_right_shift_op > m_Shr(const LHS &L, const RHS &R)
Matches logical shift operations.
Definition: PatternMatch.h:934
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:72
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
uint64_t getZExtValue() const
Get zero extended value.
Definition: APInt.h:1563
ThreeOps_match< Cond, LHS, RHS, Instruction::Select > m_Select(const Cond &C, const LHS &L, const RHS &R)
Matches SelectInst.
This class represents lattice values for constants.
Definition: AllocatorList.h:24
BinaryOps getOpcode() const
Definition: InstrTypes.h:312
#define LLVM_FALLTHROUGH
Definition: Compiler.h:86
BinaryOp_match< LHS, RHS, Instruction::SRem > m_SRem(const LHS &L, const RHS &R)
Definition: PatternMatch.h:738
This class represents zero extension of integer types.
BinaryOp_match< LHS, RHS, Instruction::Mul > m_Mul(const LHS &L, const RHS &R)
Definition: PatternMatch.h:702
static bool canEvaluateShifted(Value *V, unsigned NumBits, bool IsLeftShift, InstCombiner &IC, Instruction *CxtI)
See if we can compute the specified value, but shifted logically to the left or right by some number ...
static APInt getLowBitsSet(unsigned numBits, unsigned loBitsSet)
Get a value with low bits set.
Definition: APInt.h:648
class_match< Constant > m_Constant()
Match an arbitrary Constant and ignore it.
Definition: PatternMatch.h:91
const Value * getTrueValue() const
BinaryOp_match< LHS, RHS, Instruction::AShr > m_AShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:780
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:705
void Add(Instruction *I)
Add - Add the specified instruction to the worklist if it isn&#39;t already in it.
This class represents a sign extension of integer types.
Value * SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, const SimplifyQuery &Q)
Given operands for a Shl, fold the result or return null.
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:230
bool hasNoSignedWrap() const
Determine whether the no signed wrap flag is set.
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:265
Value * SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, const SimplifyQuery &Q)
Given operands for a LShr, fold the result or return null.
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
This class represents the LLVM &#39;select&#39; instruction.
Instruction * commonShiftTransforms(BinaryOperator &I)
Exact_match< T > m_Exact(const T &SubPattern)
Definition: PatternMatch.h:975
static Optional< unsigned > getOpcode(ArrayRef< VPValue *> Values)
Returns the opcode of Values or ~0 if they do not all agree.
Definition: VPlanSLP.cpp:197
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:743
The core instruction combiner logic.
bool MaskedValueIsZero(const Value *V, const APInt &Mask, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return true if &#39;V & Mask&#39; is known to be zero.
void lshrInPlace(unsigned ShiftAmt)
Logical right-shift this APInt by ShiftAmt in place.
Definition: APInt.h:978
BinaryOp_match< LHS, RHS, Instruction::Add > m_Add(const LHS &L, const RHS &R)
Definition: PatternMatch.h:643
Constant * ConstantFoldConstant(const Constant *C, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldConstant - Attempt to fold the constant using the specified DataLayout.
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1639
void setIsExact(bool b=true)
Set or clear the exact flag on this instruction, which must be an operator which supports this flag...
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.
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:126
bool isKnownNonNegative(const Value *V, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Returns true if the give value is known to be non-negative.
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power-of-2.
Definition: PatternMatch.h:386
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:292
This class represents a truncation of integer types.
Value * getOperand(unsigned i) const
Definition: User.h:170
static APInt getHighBitsSet(unsigned numBits, unsigned hiBitsSet)
Get a value with high bits set.
Definition: APInt.h:636
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:63
bool isNegative() const
Determine sign of this APInt.
Definition: APInt.h:364
unsigned ComputeNumSignBits(const Value *Op, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return the number of times the sign bit of the register is replicated into the other bits...
BinaryOp_match< LHS, RHS, Instruction::LShr > m_LShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:774
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
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
constexpr bool isPowerOf2_32(uint32_t Value)
Return true if the argument is a power of two > 0.
Definition: MathExtras.h:429
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1185
This is an important base class in LLVM.
Definition: Constant.h:42
static unsigned getScalarSizeInBits(Type *Ty)
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:503
BinaryOp_match< LHS, RHS, Instruction::Shl > m_Shl(const LHS &L, const RHS &R)
Definition: PatternMatch.h:768
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:75
static Constant * getAllOnesValue(Type *Ty)
Definition: Constants.cpp:319
Instruction * visitLShr(BinaryOperator &I)
static wasm::ValType getType(const TargetRegisterClass *RC)
Value * getIncomingValue(unsigned i) const
Return incoming value number x.
bool isExact() const
Determine whether the exact flag is set.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
TargetLibraryInfo & getTargetLibraryInfo() const
InstCombineWorklist & Worklist
A worklist of the instructions that need to be simplified.
CastClass_match< OpTy, Instruction::SExt > m_SExt(const OpTy &Op)
Matches SExt.
Intrinsic::ID getIntrinsicID() const
Return the intrinsic ID of this intrinsic.
Definition: IntrinsicInst.h:51
static APInt getSignMask(unsigned BitWidth)
Get the SignMask for a specific bit width.
Definition: APInt.h:555
static Constant * getSplat(unsigned NumElts, Constant *Elt)
Return a ConstantVector with the specified constant in each element.
Definition: Constants.cpp:1093
void setHasNoSignedWrap(bool b=true)
Set or clear the nsw flag on this instruction, which must be an operator which supports this flag...
uint64_t getLimitedValue(uint64_t Limit=~0ULL) const
getLimitedValue - If the value is smaller than the specified limit, return it, otherwise return the l...
Definition: Constants.h:251
This is the shared class of boolean and integer constants.
Definition: Constants.h:84
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type...
Definition: Type.cpp:130
static bool canEvaluateShiftedShift(unsigned OuterShAmt, bool IsOuterShl, Instruction *InnerShift, InstCombiner &IC, Instruction *CxtI)
Return true if we can simplify two logical (either left or right) shifts that have constant shift amo...
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:618
static ConstantInt * getSigned(IntegerType *Ty, int64_t V)
Return a ConstantInt with the specified value for the specified type.
Definition: Constants.cpp:632
unsigned getNumIncomingValues() const
Return the number of incoming edges.
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1293
void setOperand(unsigned i, Value *Val)
Definition: User.h:175
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:133
unsigned Log2_32(uint32_t Value)
Return the floor log base 2 of the specified value, -1 if the value is zero.
Definition: MathExtras.h:539
Class to represent vector types.
Definition: DerivedTypes.h:393
Class for arbitrary precision integers.
Definition: APInt.h:70
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.
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1063
const Value * getFalseValue() const
static bool canShiftBinOpWithConstantRHS(BinaryOperator &Shift, BinaryOperator *BO, const APInt &C)
bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth=0, const Instruction *CxtI=nullptr) const
bool ugt(const APInt &RHS) const
Unsigned greather than comparison.
Definition: APInt.h:1255
uint64_t getLimitedValue(uint64_t Limit=UINT64_MAX) const
If this value is smaller than the specified limit, return it, otherwise return the limit value...
Definition: APInt.h:482
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:215
Value * SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, const SimplifyQuery &Q)
Given operands for a AShr, fold the result or return nulll.
#define I(x, y, z)
Definition: MD5.cpp:58
OverflowingBinaryOp_match< LHS, RHS, Instruction::Shl, OverflowingBinaryOperator::NoSignedWrap > m_NSWShl(const LHS &L, const RHS &R)
Definition: PatternMatch.h:837
static Value * getShiftedValue(Value *V, unsigned NumBits, bool isLeftShift, InstCombiner &IC, const DataLayout &DL)
When canEvaluateShifted() returns true for an expression, this function inserts the new computation t...
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
static Constant * getShl(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2284
bool isLogicalShift() const
Return true if this is a logical shift left or a logical shift right.
Definition: Instruction.h:163
bool hasNoUnsignedWrap() const
Determine whether the no unsigned wrap flag is set.
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1124
void setHasNoUnsignedWrap(bool b=true)
Set or clear the nuw flag on this instruction, which must be an operator which supports this flag...
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static Value * foldShiftedShift(BinaryOperator *InnerShift, unsigned OuterShAmt, bool IsOuterShl, InstCombiner::BuilderTy &Builder)
Fold OuterShift (InnerShift X, C1), C2.
LLVM Value Representation.
Definition: Value.h:73
This file provides internal interfaces used to implement the InstCombine.
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
Value * CreateLShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1084
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:413
Instruction * visitAShr(BinaryOperator &I)
void setIncomingValue(unsigned i, Value *V)
Instruction * visitShl(BinaryOperator &I)
static BinaryOperator * CreateMul(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
#define LLVM_DEBUG(X)
Definition: Debug.h:123
op_range incoming_values()
Instruction * FoldShiftByConstant(Value *Op0, Constant *Op1, BinaryOperator &I)
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:44
static Constant * get(unsigned Opcode, Constant *C1, unsigned Flags=0, Type *OnlyIfReducedTy=nullptr)
get - Return a unary operator constant expression, folding if possible.
Definition: Constants.cpp:1780