LLVM  6.0.0svn
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  unsigned InnerShAmt = InnerShiftConst->getZExtValue();
91  if (InnerShAmt == OuterShAmt)
92  return true;
93 
94  // If the 2nd shift is bigger than the 1st, we can fold:
95  // lshr (shl X, C1), C2 --> and (shl X, C1 - C2), C3
96  // shl (lshr X, C1), C2 --> and (lshr X, C1 - C2), C3
97  // but it isn't profitable unless we know the and'd out bits are already zero.
98  // Also, check that the inner shift is valid (less than the type width) or
99  // we'll crash trying to produce the bit mask for the 'and'.
100  unsigned TypeWidth = InnerShift->getType()->getScalarSizeInBits();
101  if (InnerShAmt > OuterShAmt && InnerShAmt < TypeWidth) {
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->getZExtValue() == 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  DEBUG(dbgs() << "ICE: GetShiftedValue propagating shift through expression"
360  " to eliminate shift:\n IN: " << *Op0 << "\n SH: " << I <<"\n");
361 
362  return replaceInstUsesWith(
363  I, getShiftedValue(Op0, Op1C->getZExtValue(), isLeftShift, *this, DL));
364  }
365 
366  // See if we can simplify any instructions used by the instruction whose sole
367  // purpose is to compute bits we don't care about.
368  unsigned TypeBits = Op0->getType()->getScalarSizeInBits();
369 
370  assert(!Op1C->uge(TypeBits) &&
371  "Shift over the type width should have been removed already");
372 
373  if (Instruction *FoldedShift = foldOpWithConstantIntoOperand(I))
374  return FoldedShift;
375 
376  // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
377  if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
378  Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
379  // If 'shift2' is an ashr, we would have to get the sign bit into a funny
380  // place. Don't try to do this transformation in this case. Also, we
381  // require that the input operand is a shift-by-constant so that we have
382  // confidence that the shifts will get folded together. We could do this
383  // xform in more cases, but it is unlikely to be profitable.
384  if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
385  isa<ConstantInt>(TrOp->getOperand(1))) {
386  // Okay, we'll do this xform. Make the shift of shift.
387  Constant *ShAmt =
388  ConstantExpr::getZExt(cast<Constant>(Op1), TrOp->getType());
389  // (shift2 (shift1 & 0x00FF), c2)
390  Value *NSh = Builder.CreateBinOp(I.getOpcode(), TrOp, ShAmt, I.getName());
391 
392  // For logical shifts, the truncation has the effect of making the high
393  // part of the register be zeros. Emulate this by inserting an AND to
394  // clear the top bits as needed. This 'and' will usually be zapped by
395  // other xforms later if dead.
396  unsigned SrcSize = TrOp->getType()->getScalarSizeInBits();
397  unsigned DstSize = TI->getType()->getScalarSizeInBits();
398  APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
399 
400  // The mask we constructed says what the trunc would do if occurring
401  // between the shifts. We want to know the effect *after* the second
402  // shift. We know that it is a logical shift by a constant, so adjust the
403  // mask as appropriate.
404  if (I.getOpcode() == Instruction::Shl)
405  MaskV <<= Op1C->getZExtValue();
406  else {
407  assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
408  MaskV.lshrInPlace(Op1C->getZExtValue());
409  }
410 
411  // shift1 & 0x00FF
412  Value *And = Builder.CreateAnd(NSh,
413  ConstantInt::get(I.getContext(), MaskV),
414  TI->getName());
415 
416  // Return the value truncated to the interesting size.
417  return new TruncInst(And, I.getType());
418  }
419  }
420 
421  if (Op0->hasOneUse()) {
422  if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
423  // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
424  Value *V1, *V2;
425  ConstantInt *CC;
426  switch (Op0BO->getOpcode()) {
427  default: break;
428  case Instruction::Add:
429  case Instruction::And:
430  case Instruction::Or:
431  case Instruction::Xor: {
432  // These operators commute.
433  // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
434  if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
435  match(Op0BO->getOperand(1), m_Shr(m_Value(V1),
436  m_Specific(Op1)))) {
437  Value *YS = // (Y << C)
438  Builder.CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
439  // (X + (Y << C))
440  Value *X = Builder.CreateBinOp(Op0BO->getOpcode(), YS, V1,
441  Op0BO->getOperand(1)->getName());
442  unsigned Op1Val = Op1C->getLimitedValue(TypeBits);
443 
444  APInt Bits = APInt::getHighBitsSet(TypeBits, TypeBits - Op1Val);
446  if (VectorType *VT = dyn_cast<VectorType>(X->getType()))
447  Mask = ConstantVector::getSplat(VT->getNumElements(), Mask);
448  return BinaryOperator::CreateAnd(X, Mask);
449  }
450 
451  // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
452  Value *Op0BOOp1 = Op0BO->getOperand(1);
453  if (isLeftShift && Op0BOOp1->hasOneUse() &&
454  match(Op0BOOp1,
455  m_And(m_OneUse(m_Shr(m_Value(V1), m_Specific(Op1))),
456  m_ConstantInt(CC)))) {
457  Value *YS = // (Y << C)
458  Builder.CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
459  // X & (CC << C)
460  Value *XM = Builder.CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
461  V1->getName()+".mask");
462  return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
463  }
465  }
466 
467  case Instruction::Sub: {
468  // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
469  if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
470  match(Op0BO->getOperand(0), m_Shr(m_Value(V1),
471  m_Specific(Op1)))) {
472  Value *YS = // (Y << C)
473  Builder.CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
474  // (X + (Y << C))
475  Value *X = Builder.CreateBinOp(Op0BO->getOpcode(), V1, YS,
476  Op0BO->getOperand(0)->getName());
477  unsigned Op1Val = Op1C->getLimitedValue(TypeBits);
478 
479  APInt Bits = APInt::getHighBitsSet(TypeBits, TypeBits - Op1Val);
481  if (VectorType *VT = dyn_cast<VectorType>(X->getType()))
482  Mask = ConstantVector::getSplat(VT->getNumElements(), Mask);
483  return BinaryOperator::CreateAnd(X, Mask);
484  }
485 
486  // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
487  if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
488  match(Op0BO->getOperand(0),
489  m_And(m_OneUse(m_Shr(m_Value(V1), m_Value(V2))),
490  m_ConstantInt(CC))) && V2 == Op1) {
491  Value *YS = // (Y << C)
492  Builder.CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
493  // X & (CC << C)
494  Value *XM = Builder.CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
495  V1->getName()+".mask");
496 
497  return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
498  }
499 
500  break;
501  }
502  }
503 
504 
505  // If the operand is a bitwise operator with a constant RHS, and the
506  // shift is the only use, we can pull it out of the shift.
507  const APInt *Op0C;
508  if (match(Op0BO->getOperand(1), m_APInt(Op0C))) {
509  if (canShiftBinOpWithConstantRHS(I, Op0BO, *Op0C)) {
510  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
511  cast<Constant>(Op0BO->getOperand(1)), Op1);
512 
513  Value *NewShift =
514  Builder.CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1);
515  NewShift->takeName(Op0BO);
516 
517  return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
518  NewRHS);
519  }
520  }
521 
522  // If the operand is a subtract with a constant LHS, and the shift
523  // is the only use, we can pull it out of the shift.
524  // This folds (shl (sub C1, X), C2) -> (sub (C1 << C2), (shl X, C2))
525  if (isLeftShift && Op0BO->getOpcode() == Instruction::Sub &&
526  match(Op0BO->getOperand(0), m_APInt(Op0C))) {
527  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
528  cast<Constant>(Op0BO->getOperand(0)), Op1);
529 
530  Value *NewShift = Builder.CreateShl(Op0BO->getOperand(1), Op1);
531  NewShift->takeName(Op0BO);
532 
533  return BinaryOperator::CreateSub(NewRHS, NewShift);
534  }
535  }
536 
537  // If we have a select that conditionally executes some binary operator,
538  // see if we can pull it the select and operator through the shift.
539  //
540  // For example, turning:
541  // shl (select C, (add X, C1), X), C2
542  // Into:
543  // Y = shl X, C2
544  // select C, (add Y, C1 << C2), Y
545  Value *Cond;
546  BinaryOperator *TBO;
547  Value *FalseVal;
548  if (match(Op0, m_Select(m_Value(Cond), m_OneUse(m_BinOp(TBO)),
549  m_Value(FalseVal)))) {
550  const APInt *C;
551  if (!isa<Constant>(FalseVal) && TBO->getOperand(0) == FalseVal &&
552  match(TBO->getOperand(1), m_APInt(C)) &&
553  canShiftBinOpWithConstantRHS(I, TBO, *C)) {
554  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
555  cast<Constant>(TBO->getOperand(1)), Op1);
556 
557  Value *NewShift =
558  Builder.CreateBinOp(I.getOpcode(), FalseVal, Op1);
559  Value *NewOp = Builder.CreateBinOp(TBO->getOpcode(), NewShift,
560  NewRHS);
561  return SelectInst::Create(Cond, NewOp, NewShift);
562  }
563  }
564 
565  BinaryOperator *FBO;
566  Value *TrueVal;
567  if (match(Op0, m_Select(m_Value(Cond), m_Value(TrueVal),
568  m_OneUse(m_BinOp(FBO))))) {
569  const APInt *C;
570  if (!isa<Constant>(TrueVal) && FBO->getOperand(0) == TrueVal &&
571  match(FBO->getOperand(1), m_APInt(C)) &&
572  canShiftBinOpWithConstantRHS(I, FBO, *C)) {
573  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
574  cast<Constant>(FBO->getOperand(1)), Op1);
575 
576  Value *NewShift =
577  Builder.CreateBinOp(I.getOpcode(), TrueVal, Op1);
578  Value *NewOp = Builder.CreateBinOp(FBO->getOpcode(), NewShift,
579  NewRHS);
580  return SelectInst::Create(Cond, NewShift, NewOp);
581  }
582  }
583  }
584 
585  return nullptr;
586 }
587 
589  if (Value *V = SimplifyVectorOp(I))
590  return replaceInstUsesWith(I, V);
591 
592  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
593  if (Value *V =
595  SQ.getWithInstruction(&I)))
596  return replaceInstUsesWith(I, V);
597 
598  if (Instruction *V = commonShiftTransforms(I))
599  return V;
600 
601  const APInt *ShAmtAPInt;
602  if (match(Op1, m_APInt(ShAmtAPInt))) {
603  unsigned ShAmt = ShAmtAPInt->getZExtValue();
604  unsigned BitWidth = I.getType()->getScalarSizeInBits();
605  Type *Ty = I.getType();
606 
607  // shl (zext X), ShAmt --> zext (shl X, ShAmt)
608  // This is only valid if X would have zeros shifted out.
609  Value *X;
610  if (match(Op0, m_ZExt(m_Value(X)))) {
611  unsigned SrcWidth = X->getType()->getScalarSizeInBits();
612  if (ShAmt < SrcWidth &&
613  MaskedValueIsZero(X, APInt::getHighBitsSet(SrcWidth, ShAmt), 0, &I))
614  return new ZExtInst(Builder.CreateShl(X, ShAmt), Ty);
615  }
616 
617  // (X >> C) << C --> X & (-1 << C)
618  if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1)))) {
619  APInt Mask(APInt::getHighBitsSet(BitWidth, BitWidth - ShAmt));
620  return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, Mask));
621  }
622 
623  // Be careful about hiding shl instructions behind bit masks. They are used
624  // to represent multiplies by a constant, and it is important that simple
625  // arithmetic expressions are still recognizable by scalar evolution.
626  // The inexact versions are deferred to DAGCombine, so we don't hide shl
627  // behind a bit mask.
628  const APInt *ShOp1;
629  if (match(Op0, m_Exact(m_Shr(m_Value(X), m_APInt(ShOp1))))) {
630  unsigned ShrAmt = ShOp1->getZExtValue();
631  if (ShrAmt < ShAmt) {
632  // If C1 < C2: (X >>?,exact C1) << C2 --> X << (C2 - C1)
633  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShrAmt);
634  auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
635  NewShl->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
636  NewShl->setHasNoSignedWrap(I.hasNoSignedWrap());
637  return NewShl;
638  }
639  if (ShrAmt > ShAmt) {
640  // If C1 > C2: (X >>?exact C1) << C2 --> X >>?exact (C1 - C2)
641  Constant *ShiftDiff = ConstantInt::get(Ty, ShrAmt - ShAmt);
642  auto *NewShr = BinaryOperator::Create(
643  cast<BinaryOperator>(Op0)->getOpcode(), X, ShiftDiff);
644  NewShr->setIsExact(true);
645  return NewShr;
646  }
647  }
648 
649  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShOp1)))) {
650  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
651  // Oversized shifts are simplified to zero in InstSimplify.
652  if (AmtSum < BitWidth)
653  // (X << C1) << C2 --> X << (C1 + C2)
654  return BinaryOperator::CreateShl(X, ConstantInt::get(Ty, AmtSum));
655  }
656 
657  // If the shifted-out value is known-zero, then this is a NUW shift.
658  if (!I.hasNoUnsignedWrap() &&
659  MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, ShAmt), 0, &I)) {
661  return &I;
662  }
663 
664  // If the shifted-out value is all signbits, then this is a NSW shift.
665  if (!I.hasNoSignedWrap() && ComputeNumSignBits(Op0, 0, &I) > ShAmt) {
666  I.setHasNoSignedWrap();
667  return &I;
668  }
669  }
670 
671  Constant *C1;
672  if (match(Op1, m_Constant(C1))) {
673  Constant *C2;
674  Value *X;
675  // (C2 << X) << C1 --> (C2 << C1) << X
676  if (match(Op0, m_OneUse(m_Shl(m_Constant(C2), m_Value(X)))))
677  return BinaryOperator::CreateShl(ConstantExpr::getShl(C2, C1), X);
678 
679  // (X * C2) << C1 --> X * (C2 << C1)
680  if (match(Op0, m_Mul(m_Value(X), m_Constant(C2))))
682  }
683 
684  return nullptr;
685 }
686 
688  if (Value *V = SimplifyVectorOp(I))
689  return replaceInstUsesWith(I, V);
690 
691  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
692  if (Value *V =
693  SimplifyLShrInst(Op0, Op1, I.isExact(), SQ.getWithInstruction(&I)))
694  return replaceInstUsesWith(I, V);
695 
696  if (Instruction *R = commonShiftTransforms(I))
697  return R;
698 
699  Type *Ty = I.getType();
700  const APInt *ShAmtAPInt;
701  if (match(Op1, m_APInt(ShAmtAPInt))) {
702  unsigned ShAmt = ShAmtAPInt->getZExtValue();
703  unsigned BitWidth = Ty->getScalarSizeInBits();
704  auto *II = dyn_cast<IntrinsicInst>(Op0);
705  if (II && isPowerOf2_32(BitWidth) && Log2_32(BitWidth) == ShAmt &&
706  (II->getIntrinsicID() == Intrinsic::ctlz ||
707  II->getIntrinsicID() == Intrinsic::cttz ||
708  II->getIntrinsicID() == Intrinsic::ctpop)) {
709  // ctlz.i32(x)>>5 --> zext(x == 0)
710  // cttz.i32(x)>>5 --> zext(x == 0)
711  // ctpop.i32(x)>>5 --> zext(x == -1)
712  bool IsPop = II->getIntrinsicID() == Intrinsic::ctpop;
713  Constant *RHS = ConstantInt::getSigned(Ty, IsPop ? -1 : 0);
714  Value *Cmp = Builder.CreateICmpEQ(II->getArgOperand(0), RHS);
715  return new ZExtInst(Cmp, Ty);
716  }
717 
718  Value *X;
719  const APInt *ShOp1;
720  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShOp1)))) {
721  unsigned ShlAmt = ShOp1->getZExtValue();
722  if (ShlAmt < ShAmt) {
723  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShlAmt);
724  if (cast<BinaryOperator>(Op0)->hasNoUnsignedWrap()) {
725  // (X <<nuw C1) >>u C2 --> X >>u (C2 - C1)
726  auto *NewLShr = BinaryOperator::CreateLShr(X, ShiftDiff);
727  NewLShr->setIsExact(I.isExact());
728  return NewLShr;
729  }
730  // (X << C1) >>u C2 --> (X >>u (C2 - C1)) & (-1 >> C2)
731  Value *NewLShr = Builder.CreateLShr(X, ShiftDiff, "", I.isExact());
732  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
733  return BinaryOperator::CreateAnd(NewLShr, ConstantInt::get(Ty, Mask));
734  }
735  if (ShlAmt > ShAmt) {
736  Constant *ShiftDiff = ConstantInt::get(Ty, ShlAmt - ShAmt);
737  if (cast<BinaryOperator>(Op0)->hasNoUnsignedWrap()) {
738  // (X <<nuw C1) >>u C2 --> X <<nuw (C1 - C2)
739  auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
740  NewShl->setHasNoUnsignedWrap(true);
741  return NewShl;
742  }
743  // (X << C1) >>u C2 --> X << (C1 - C2) & (-1 >> C2)
744  Value *NewShl = Builder.CreateShl(X, ShiftDiff);
745  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
746  return BinaryOperator::CreateAnd(NewShl, ConstantInt::get(Ty, Mask));
747  }
748  assert(ShlAmt == ShAmt);
749  // (X << C) >>u C --> X & (-1 >>u C)
750  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
751  return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, Mask));
752  }
753 
754  if (match(Op0, m_OneUse(m_ZExt(m_Value(X)))) &&
755  (!Ty->isIntegerTy() || shouldChangeType(Ty, X->getType()))) {
756  assert(ShAmt < X->getType()->getScalarSizeInBits() &&
757  "Big shift not simplified to zero?");
758  // lshr (zext iM X to iN), C --> zext (lshr X, C) to iN
759  Value *NewLShr = Builder.CreateLShr(X, ShAmt);
760  return new ZExtInst(NewLShr, Ty);
761  }
762 
763  if (match(Op0, m_SExt(m_Value(X))) &&
764  (!Ty->isIntegerTy() || shouldChangeType(Ty, X->getType()))) {
765  // Are we moving the sign bit to the low bit and widening with high zeros?
766  unsigned SrcTyBitWidth = X->getType()->getScalarSizeInBits();
767  if (ShAmt == BitWidth - 1) {
768  // lshr (sext i1 X to iN), N-1 --> zext X to iN
769  if (SrcTyBitWidth == 1)
770  return new ZExtInst(X, Ty);
771 
772  // lshr (sext iM X to iN), N-1 --> zext (lshr X, M-1) to iN
773  if (Op0->hasOneUse()) {
774  Value *NewLShr = Builder.CreateLShr(X, SrcTyBitWidth - 1);
775  return new ZExtInst(NewLShr, Ty);
776  }
777  }
778 
779  // lshr (sext iM X to iN), N-M --> zext (ashr X, min(N-M, M-1)) to iN
780  if (ShAmt == BitWidth - SrcTyBitWidth && Op0->hasOneUse()) {
781  // The new shift amount can't be more than the narrow source type.
782  unsigned NewShAmt = std::min(ShAmt, SrcTyBitWidth - 1);
783  Value *AShr = Builder.CreateAShr(X, NewShAmt);
784  return new ZExtInst(AShr, Ty);
785  }
786  }
787 
788  if (match(Op0, m_LShr(m_Value(X), m_APInt(ShOp1)))) {
789  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
790  // Oversized shifts are simplified to zero in InstSimplify.
791  if (AmtSum < BitWidth)
792  // (X >>u C1) >>u C2 --> X >>u (C1 + C2)
793  return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
794  }
795 
796  // If the shifted-out value is known-zero, then this is an exact shift.
797  if (!I.isExact() &&
798  MaskedValueIsZero(Op0, APInt::getLowBitsSet(BitWidth, ShAmt), 0, &I)) {
799  I.setIsExact();
800  return &I;
801  }
802  }
803  return nullptr;
804 }
805 
807  if (Value *V = SimplifyVectorOp(I))
808  return replaceInstUsesWith(I, V);
809 
810  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
811  if (Value *V =
812  SimplifyAShrInst(Op0, Op1, I.isExact(), SQ.getWithInstruction(&I)))
813  return replaceInstUsesWith(I, V);
814 
815  if (Instruction *R = commonShiftTransforms(I))
816  return R;
817 
818  Type *Ty = I.getType();
819  unsigned BitWidth = Ty->getScalarSizeInBits();
820  const APInt *ShAmtAPInt;
821  if (match(Op1, m_APInt(ShAmtAPInt))) {
822  unsigned ShAmt = ShAmtAPInt->getZExtValue();
823 
824  // If the shift amount equals the difference in width of the destination
825  // and source scalar types:
826  // ashr (shl (zext X), C), C --> sext X
827  Value *X;
828  if (match(Op0, m_Shl(m_ZExt(m_Value(X)), m_Specific(Op1))) &&
829  ShAmt == BitWidth - X->getType()->getScalarSizeInBits())
830  return new SExtInst(X, Ty);
831 
832  // We can't handle (X << C1) >>s C2. It shifts arbitrary bits in. However,
833  // we can handle (X <<nsw C1) >>s C2 since it only shifts in sign bits.
834  const APInt *ShOp1;
835  if (match(Op0, m_NSWShl(m_Value(X), m_APInt(ShOp1)))) {
836  unsigned ShlAmt = ShOp1->getZExtValue();
837  if (ShlAmt < ShAmt) {
838  // (X <<nsw C1) >>s C2 --> X >>s (C2 - C1)
839  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShlAmt);
840  auto *NewAShr = BinaryOperator::CreateAShr(X, ShiftDiff);
841  NewAShr->setIsExact(I.isExact());
842  return NewAShr;
843  }
844  if (ShlAmt > ShAmt) {
845  // (X <<nsw C1) >>s C2 --> X <<nsw (C1 - C2)
846  Constant *ShiftDiff = ConstantInt::get(Ty, ShlAmt - ShAmt);
847  auto *NewShl = BinaryOperator::Create(Instruction::Shl, X, ShiftDiff);
848  NewShl->setHasNoSignedWrap(true);
849  return NewShl;
850  }
851  }
852 
853  if (match(Op0, m_AShr(m_Value(X), m_APInt(ShOp1)))) {
854  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
855  // Oversized arithmetic shifts replicate the sign bit.
856  AmtSum = std::min(AmtSum, BitWidth - 1);
857  // (X >>s C1) >>s C2 --> X >>s (C1 + C2)
858  return BinaryOperator::CreateAShr(X, ConstantInt::get(Ty, AmtSum));
859  }
860 
861  if (match(Op0, m_OneUse(m_SExt(m_Value(X)))) &&
862  (Ty->isVectorTy() || shouldChangeType(Ty, X->getType()))) {
863  // ashr (sext X), C --> sext (ashr X, C')
864  Type *SrcTy = X->getType();
865  ShAmt = std::min(ShAmt, SrcTy->getScalarSizeInBits() - 1);
866  Value *NewSh = Builder.CreateAShr(X, ConstantInt::get(SrcTy, ShAmt));
867  return new SExtInst(NewSh, Ty);
868  }
869 
870  // If the shifted-out value is known-zero, then this is an exact shift.
871  if (!I.isExact() &&
872  MaskedValueIsZero(Op0, APInt::getLowBitsSet(BitWidth, ShAmt), 0, &I)) {
873  I.setIsExact();
874  return &I;
875  }
876  }
877 
878  // See if we can turn a signed shr into an unsigned shr.
879  if (MaskedValueIsZero(Op0, APInt::getSignMask(BitWidth), 0, &I))
880  return BinaryOperator::CreateLShr(Op0, Op1);
881 
882  return nullptr;
883 }
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:574
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:758
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:109
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:1542
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
BinaryOps getOpcode() const
Definition: InstrTypes.h:523
BinaryOp_match< LHS, RHS, Instruction::SRem > m_SRem(const LHS &L, const RHS &R)
Definition: PatternMatch.h:562
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:526
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:641
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:604
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:728
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:227
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:207
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:799
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:668
The core instruction combiner logic.
void lshrInPlace(unsigned ShiftAmt)
Logical right-shift this APInt by ShiftAmt in place.
Definition: APInt.h:966
BinaryOp_match< LHS, RHS, Instruction::Add > m_Add(const LHS &L, const RHS &R)
Definition: PatternMatch.h:502
Constant * ConstantFoldConstant(const Constant *C, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldConstant - Attempt to fold the constant using the specified DataLayout.
static Constant * get(unsigned Opcode, Constant *C1, Constant *C2, unsigned Flags=0, Type *OnlyIfReducedTy=nullptr)
get - Return a binary or shift operator constant expression, folding if possible. ...
Definition: Constants.cpp:1711
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1570
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.
Definition: PatternMatch.h:924
class_match< ConstantInt > m_ConstantInt()
Match an arbitrary ConstantInt and ignore it.
Definition: PatternMatch.h:83
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:125
SelectClass_match< Cond, LHS, RHS > m_Select(const Cond &C, const LHS &L, const RHS &R)
Definition: PatternMatch.h:869
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power of 2.
Definition: PatternMatch.h:330
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:154
static APInt getHighBitsSet(unsigned numBits, unsigned hiBitsSet)
Get a value with high bits set.
Definition: APInt.h:629
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:63
bool isNegative() const
Determine sign of this APInt.
Definition: APInt.h:357
BinaryOp_match< LHS, RHS, Instruction::LShr > m_LShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:598
uint64_t getZExtValue() const
Return the constant as a 64-bit unsigned integer value after it has been zero extended as appropriate...
Definition: Constants.h:149
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:260
constexpr bool isPowerOf2_32(uint32_t Value)
Return true if the argument is a power of two > 0.
Definition: MathExtras.h:421
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
bool isKnownNonNegative(const Value *V, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr)
Returns true if the give value is known to be non-negative.
This is an important base class in LLVM.
Definition: Constant.h:42
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)
Return true if &#39;V & Mask&#39; is known to be zero.
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:382
BinaryOp_match< LHS, RHS, Instruction::Shl > m_Shl(const LHS &L, const RHS &R)
Definition: PatternMatch.h:592
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:75
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.
Definition: PatternMatch.h:918
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:548
static Constant * getSplat(unsigned NumElts, Constant *Elt)
Return a ConstantVector with the specified constant in each element.
Definition: Constants.cpp:1024
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 ComputeNumSignBits(const Value *Op, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr)
Return the number of times the sign bit of the register is replicated into the other bits...
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:560
static ConstantInt * getSigned(IntegerType *Ty, int64_t V)
Return a ConstantInt with the specified value for the specified type.
Definition: Constants.cpp:574
unsigned getNumIncomingValues() const
Return the number of incoming edges.
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1272
void setOperand(unsigned i, Value *Val)
Definition: User.h:159
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
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:531
Class to represent vector types.
Definition: DerivedTypes.h:393
Class for arbitrary precision integers.
Definition: APInt.h:69
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:1012
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
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:475
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:220
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:661
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:2186
bool isLogicalShift() const
Return true if this is a logical shift left or a logical shift right.
Definition: Instruction.h:150
bool hasNoUnsignedWrap() const
Determine whether the no unsigned wrap flag is set.
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1067
void setHasNoUnsignedWrap(bool b=true)
Set or clear the nsw 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.
#define LLVM_FALLTHROUGH
LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
Definition: Compiler.h:235
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:1031
#define DEBUG(X)
Definition: Debug.h:118
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:414
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)
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