LLVM  10.0.0svn
InstCombineShifts.cpp
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1 //===- InstCombineShifts.cpp ----------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the visitShl, visitLShr, and visitAShr functions.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "InstCombineInternal.h"
16 #include "llvm/IR/IntrinsicInst.h"
17 #include "llvm/IR/PatternMatch.h"
18 using namespace llvm;
19 using namespace PatternMatch;
20 
21 #define DEBUG_TYPE "instcombine"
22 
23 // Given pattern:
24 // (x shiftopcode Q) shiftopcode K
25 // we should rewrite it as
26 // x shiftopcode (Q+K) iff (Q+K) u< bitwidth(x)
27 // This is valid for any shift, but they must be identical.
28 static Instruction *
30  const SimplifyQuery &SQ,
31  InstCombiner::BuilderTy &Builder) {
32  // Look for a shift of some instruction, ignore zext of shift amount if any.
33  Instruction *Sh0Op0;
34  Value *ShAmt0;
35  if (!match(Sh0,
36  m_Shift(m_Instruction(Sh0Op0), m_ZExtOrSelf(m_Value(ShAmt0)))))
37  return nullptr;
38 
39  // If there is a truncation between the two shifts, we must make note of it
40  // and look through it. The truncation imposes additional constraints on the
41  // transform.
42  Instruction *Sh1;
43  Value *Trunc = nullptr;
44  match(Sh0Op0,
46  m_Instruction(Sh1)));
47 
48  // Inner shift: (x shiftopcode ShAmt1)
49  // Like with other shift, ignore zext of shift amount if any.
50  Value *X, *ShAmt1;
51  if (!match(Sh1, m_Shift(m_Value(X), m_ZExtOrSelf(m_Value(ShAmt1)))))
52  return nullptr;
53 
54  // We have two shift amounts from two different shifts. The types of those
55  // shift amounts may not match. If that's the case let's bailout now..
56  if (ShAmt0->getType() != ShAmt1->getType())
57  return nullptr;
58 
59  // The shift opcodes must be identical.
60  Instruction::BinaryOps ShiftOpcode = Sh0->getOpcode();
61  if (ShiftOpcode != Sh1->getOpcode())
62  return nullptr;
63 
64  // If we saw truncation, we'll need to produce extra instruction,
65  // and for that one of the operands of the shift must be one-use.
66  if (Trunc && !match(Sh0, m_c_BinOp(m_OneUse(m_Value()), m_Value())))
67  return nullptr;
68 
69  // Can we fold (ShAmt0+ShAmt1) ?
70  auto *NewShAmt = dyn_cast_or_null<Constant>(
71  SimplifyAddInst(ShAmt0, ShAmt1, /*isNSW=*/false, /*isNUW=*/false,
72  SQ.getWithInstruction(Sh0)));
73  if (!NewShAmt)
74  return nullptr; // Did not simplify.
75  unsigned NewShAmtBitWidth = NewShAmt->getType()->getScalarSizeInBits();
76  unsigned XBitWidth = X->getType()->getScalarSizeInBits();
77  // Is the new shift amount smaller than the bit width of inner/new shift?
78  if (!match(NewShAmt, m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_ULT,
79  APInt(NewShAmtBitWidth, XBitWidth))))
80  return nullptr; // FIXME: could perform constant-folding.
81 
82  // If there was a truncation, and we have a right-shift, we can only fold if
83  // we are left with the original sign bit.
84  // FIXME: zero shift amount is also legal here, but we can't *easily* check
85  // more than one predicate so it's not really worth it.
86  if (Trunc && ShiftOpcode != Instruction::BinaryOps::Shl &&
87  !match(NewShAmt,
88  m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_EQ,
89  APInt(NewShAmtBitWidth, XBitWidth - 1))))
90  return nullptr;
91 
92  // All good, we can do this fold.
93  NewShAmt = ConstantExpr::getZExtOrBitCast(NewShAmt, X->getType());
94 
95  BinaryOperator *NewShift = BinaryOperator::Create(ShiftOpcode, X, NewShAmt);
96 
97  // The flags can only be propagated if there wasn't a trunc.
98  if (!Trunc) {
99  // If the pattern did not involve trunc, and both of the original shifts
100  // had the same flag set, preserve the flag.
101  if (ShiftOpcode == Instruction::BinaryOps::Shl) {
102  NewShift->setHasNoUnsignedWrap(Sh0->hasNoUnsignedWrap() &&
103  Sh1->hasNoUnsignedWrap());
104  NewShift->setHasNoSignedWrap(Sh0->hasNoSignedWrap() &&
105  Sh1->hasNoSignedWrap());
106  } else {
107  NewShift->setIsExact(Sh0->isExact() && Sh1->isExact());
108  }
109  }
110 
111  Instruction *Ret = NewShift;
112  if (Trunc) {
113  Builder.Insert(NewShift);
114  Ret = CastInst::Create(Instruction::Trunc, NewShift, Sh0->getType());
115  }
116 
117  return Ret;
118 }
119 
120 // Try to replace `undef` constants in C with Replacement.
121 static Constant *replaceUndefsWith(Constant *C, Constant *Replacement) {
122  if (C && match(C, m_Undef()))
123  return Replacement;
124 
125  if (auto *CV = dyn_cast<ConstantVector>(C)) {
126  llvm::SmallVector<Constant *, 32> NewOps(CV->getNumOperands());
127  for (unsigned i = 0, NumElts = NewOps.size(); i != NumElts; ++i) {
128  Constant *EltC = CV->getOperand(i);
129  NewOps[i] = EltC && match(EltC, m_Undef()) ? Replacement : EltC;
130  }
131  return ConstantVector::get(NewOps);
132  }
133 
134  // Don't know how to deal with this constant.
135  return C;
136 }
137 
138 // If we have some pattern that leaves only some low bits set, and then performs
139 // left-shift of those bits, if none of the bits that are left after the final
140 // shift are modified by the mask, we can omit the mask.
141 //
142 // There are many variants to this pattern:
143 // a) (x & ((1 << MaskShAmt) - 1)) << ShiftShAmt
144 // b) (x & (~(-1 << MaskShAmt))) << ShiftShAmt
145 // c) (x & (-1 >> MaskShAmt)) << ShiftShAmt
146 // d) (x & ((-1 << MaskShAmt) >> MaskShAmt)) << ShiftShAmt
147 // e) ((x << MaskShAmt) l>> MaskShAmt) << ShiftShAmt
148 // f) ((x << MaskShAmt) a>> MaskShAmt) << ShiftShAmt
149 // All these patterns can be simplified to just:
150 // x << ShiftShAmt
151 // iff:
152 // a,b) (MaskShAmt+ShiftShAmt) u>= bitwidth(x)
153 // c,d,e,f) (ShiftShAmt-MaskShAmt) s>= 0 (i.e. ShiftShAmt u>= MaskShAmt)
154 static Instruction *
156  const SimplifyQuery &Q,
157  InstCombiner::BuilderTy &Builder) {
158  assert(OuterShift->getOpcode() == Instruction::BinaryOps::Shl &&
159  "The input must be 'shl'!");
160 
161  Value *Masked = OuterShift->getOperand(0);
162  Value *ShiftShAmt = OuterShift->getOperand(1);
163 
164  Type *NarrowestTy = OuterShift->getType();
165  Type *WidestTy = Masked->getType();
166  // The mask must be computed in a type twice as wide to ensure
167  // that no bits are lost if the sum-of-shifts is wider than the base type.
168  Type *ExtendedTy = WidestTy->getExtendedType();
169 
170  Value *MaskShAmt;
171 
172  // ((1 << MaskShAmt) - 1)
173  auto MaskA = m_Add(m_Shl(m_One(), m_Value(MaskShAmt)), m_AllOnes());
174  // (~(-1 << maskNbits))
175  auto MaskB = m_Xor(m_Shl(m_AllOnes(), m_Value(MaskShAmt)), m_AllOnes());
176  // (-1 >> MaskShAmt)
177  auto MaskC = m_Shr(m_AllOnes(), m_Value(MaskShAmt));
178  // ((-1 << MaskShAmt) >> MaskShAmt)
179  auto MaskD =
180  m_Shr(m_Shl(m_AllOnes(), m_Value(MaskShAmt)), m_Deferred(MaskShAmt));
181 
182  Value *X;
183  Constant *NewMask;
184 
185  if (match(Masked, m_c_And(m_CombineOr(MaskA, MaskB), m_Value(X)))) {
186  // Can we simplify (MaskShAmt+ShiftShAmt) ?
187  auto *SumOfShAmts = dyn_cast_or_null<Constant>(SimplifyAddInst(
188  MaskShAmt, ShiftShAmt, /*IsNSW=*/false, /*IsNUW=*/false, Q));
189  if (!SumOfShAmts)
190  return nullptr; // Did not simplify.
191  // In this pattern SumOfShAmts correlates with the number of low bits
192  // that shall remain in the root value (OuterShift).
193 
194  // An extend of an undef value becomes zero because the high bits are never
195  // completely unknown. Replace the the `undef` shift amounts with final
196  // shift bitwidth to ensure that the value remains undef when creating the
197  // subsequent shift op.
198  SumOfShAmts = replaceUndefsWith(
199  SumOfShAmts, ConstantInt::get(SumOfShAmts->getType()->getScalarType(),
200  ExtendedTy->getScalarSizeInBits()));
201  auto *ExtendedSumOfShAmts = ConstantExpr::getZExt(SumOfShAmts, ExtendedTy);
202  // And compute the mask as usual: ~(-1 << (SumOfShAmts))
203  auto *ExtendedAllOnes = ConstantExpr::getAllOnesValue(ExtendedTy);
204  auto *ExtendedInvertedMask =
205  ConstantExpr::getShl(ExtendedAllOnes, ExtendedSumOfShAmts);
206  NewMask = ConstantExpr::getNot(ExtendedInvertedMask);
207  } else if (match(Masked, m_c_And(m_CombineOr(MaskC, MaskD), m_Value(X))) ||
208  match(Masked, m_Shr(m_Shl(m_Value(X), m_Value(MaskShAmt)),
209  m_Deferred(MaskShAmt)))) {
210  // Can we simplify (ShiftShAmt-MaskShAmt) ?
211  auto *ShAmtsDiff = dyn_cast_or_null<Constant>(SimplifySubInst(
212  ShiftShAmt, MaskShAmt, /*IsNSW=*/false, /*IsNUW=*/false, Q));
213  if (!ShAmtsDiff)
214  return nullptr; // Did not simplify.
215  // In this pattern ShAmtsDiff correlates with the number of high bits that
216  // shall be unset in the root value (OuterShift).
217 
218  // An extend of an undef value becomes zero because the high bits are never
219  // completely unknown. Replace the the `undef` shift amounts with negated
220  // bitwidth of innermost shift to ensure that the value remains undef when
221  // creating the subsequent shift op.
222  unsigned WidestTyBitWidth = WidestTy->getScalarSizeInBits();
223  ShAmtsDiff = replaceUndefsWith(
224  ShAmtsDiff, ConstantInt::get(ShAmtsDiff->getType()->getScalarType(),
225  -WidestTyBitWidth));
226  auto *ExtendedNumHighBitsToClear = ConstantExpr::getZExt(
227  ConstantExpr::getSub(ConstantInt::get(ShAmtsDiff->getType(),
228  WidestTyBitWidth,
229  /*isSigned=*/false),
230  ShAmtsDiff),
231  ExtendedTy);
232  // And compute the mask as usual: (-1 l>> (NumHighBitsToClear))
233  auto *ExtendedAllOnes = ConstantExpr::getAllOnesValue(ExtendedTy);
234  NewMask =
235  ConstantExpr::getLShr(ExtendedAllOnes, ExtendedNumHighBitsToClear);
236  } else
237  return nullptr; // Don't know anything about this pattern.
238 
239  NewMask = ConstantExpr::getTrunc(NewMask, NarrowestTy);
240 
241  // Does this mask has any unset bits? If not then we can just not apply it.
242  bool NeedMask = !match(NewMask, m_AllOnes());
243 
244  // If we need to apply a mask, there are several more restrictions we have.
245  if (NeedMask) {
246  // The old masking instruction must go away.
247  if (!Masked->hasOneUse())
248  return nullptr;
249  // The original "masking" instruction must not have been`ashr`.
250  if (match(Masked, m_AShr(m_Value(), m_Value())))
251  return nullptr;
252  }
253 
254  // No 'NUW'/'NSW'! We no longer know that we won't shift-out non-0 bits.
255  auto *NewShift =
256  BinaryOperator::Create(OuterShift->getOpcode(), X, ShiftShAmt);
257 
258  if (!NeedMask)
259  return NewShift;
260 
261  Builder.Insert(NewShift);
262  return BinaryOperator::Create(Instruction::And, NewShift, NewMask);
263 }
264 
266  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
267  assert(Op0->getType() == Op1->getType());
268 
269  // If the shift amount is a one-use `sext`, we can demote it to `zext`.
270  Value *Y;
271  if (match(Op1, m_OneUse(m_SExt(m_Value(Y))))) {
272  Value *NewExt = Builder.CreateZExt(Y, I.getType(), Op1->getName());
273  return BinaryOperator::Create(I.getOpcode(), Op0, NewExt);
274  }
275 
276  // See if we can fold away this shift.
277  if (SimplifyDemandedInstructionBits(I))
278  return &I;
279 
280  // Try to fold constant and into select arguments.
281  if (isa<Constant>(Op0))
282  if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
283  if (Instruction *R = FoldOpIntoSelect(I, SI))
284  return R;
285 
286  if (Constant *CUI = dyn_cast<Constant>(Op1))
287  if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
288  return Res;
289 
290  if (Instruction *NewShift =
292  return NewShift;
293 
294  // (C1 shift (A add C2)) -> (C1 shift C2) shift A)
295  // iff A and C2 are both positive.
296  Value *A;
297  Constant *C;
298  if (match(Op0, m_Constant()) && match(Op1, m_Add(m_Value(A), m_Constant(C))))
299  if (isKnownNonNegative(A, DL, 0, &AC, &I, &DT) &&
300  isKnownNonNegative(C, DL, 0, &AC, &I, &DT))
301  return BinaryOperator::Create(
302  I.getOpcode(), Builder.CreateBinOp(I.getOpcode(), Op0, C), A);
303 
304  // X shift (A srem B) -> X shift (A and B-1) iff B is a power of 2.
305  // Because shifts by negative values (which could occur if A were negative)
306  // are undefined.
307  const APInt *B;
308  if (Op1->hasOneUse() && match(Op1, m_SRem(m_Value(A), m_Power2(B)))) {
309  // FIXME: Should this get moved into SimplifyDemandedBits by saying we don't
310  // demand the sign bit (and many others) here??
311  Value *Rem = Builder.CreateAnd(A, ConstantInt::get(I.getType(), *B - 1),
312  Op1->getName());
313  I.setOperand(1, Rem);
314  return &I;
315  }
316 
317  return nullptr;
318 }
319 
320 /// Return true if we can simplify two logical (either left or right) shifts
321 /// that have constant shift amounts: OuterShift (InnerShift X, C1), C2.
322 static bool canEvaluateShiftedShift(unsigned OuterShAmt, bool IsOuterShl,
323  Instruction *InnerShift, InstCombiner &IC,
324  Instruction *CxtI) {
325  assert(InnerShift->isLogicalShift() && "Unexpected instruction type");
326 
327  // We need constant scalar or constant splat shifts.
328  const APInt *InnerShiftConst;
329  if (!match(InnerShift->getOperand(1), m_APInt(InnerShiftConst)))
330  return false;
331 
332  // Two logical shifts in the same direction:
333  // shl (shl X, C1), C2 --> shl X, C1 + C2
334  // lshr (lshr X, C1), C2 --> lshr X, C1 + C2
335  bool IsInnerShl = InnerShift->getOpcode() == Instruction::Shl;
336  if (IsInnerShl == IsOuterShl)
337  return true;
338 
339  // Equal shift amounts in opposite directions become bitwise 'and':
340  // lshr (shl X, C), C --> and X, C'
341  // shl (lshr X, C), C --> and X, C'
342  if (*InnerShiftConst == OuterShAmt)
343  return true;
344 
345  // If the 2nd shift is bigger than the 1st, we can fold:
346  // lshr (shl X, C1), C2 --> and (shl X, C1 - C2), C3
347  // shl (lshr X, C1), C2 --> and (lshr X, C1 - C2), C3
348  // but it isn't profitable unless we know the and'd out bits are already zero.
349  // Also, check that the inner shift is valid (less than the type width) or
350  // we'll crash trying to produce the bit mask for the 'and'.
351  unsigned TypeWidth = InnerShift->getType()->getScalarSizeInBits();
352  if (InnerShiftConst->ugt(OuterShAmt) && InnerShiftConst->ult(TypeWidth)) {
353  unsigned InnerShAmt = InnerShiftConst->getZExtValue();
354  unsigned MaskShift =
355  IsInnerShl ? TypeWidth - InnerShAmt : InnerShAmt - OuterShAmt;
356  APInt Mask = APInt::getLowBitsSet(TypeWidth, OuterShAmt) << MaskShift;
357  if (IC.MaskedValueIsZero(InnerShift->getOperand(0), Mask, 0, CxtI))
358  return true;
359  }
360 
361  return false;
362 }
363 
364 /// See if we can compute the specified value, but shifted logically to the left
365 /// or right by some number of bits. This should return true if the expression
366 /// can be computed for the same cost as the current expression tree. This is
367 /// used to eliminate extraneous shifting from things like:
368 /// %C = shl i128 %A, 64
369 /// %D = shl i128 %B, 96
370 /// %E = or i128 %C, %D
371 /// %F = lshr i128 %E, 64
372 /// where the client will ask if E can be computed shifted right by 64-bits. If
373 /// this succeeds, getShiftedValue() will be called to produce the value.
374 static bool canEvaluateShifted(Value *V, unsigned NumBits, bool IsLeftShift,
375  InstCombiner &IC, Instruction *CxtI) {
376  // We can always evaluate constants shifted.
377  if (isa<Constant>(V))
378  return true;
379 
381  if (!I) return false;
382 
383  // If this is the opposite shift, we can directly reuse the input of the shift
384  // if the needed bits are already zero in the input. This allows us to reuse
385  // the value which means that we don't care if the shift has multiple uses.
386  // TODO: Handle opposite shift by exact value.
387  ConstantInt *CI = nullptr;
388  if ((IsLeftShift && match(I, m_LShr(m_Value(), m_ConstantInt(CI)))) ||
389  (!IsLeftShift && match(I, m_Shl(m_Value(), m_ConstantInt(CI))))) {
390  if (CI->getValue() == NumBits) {
391  // TODO: Check that the input bits are already zero with MaskedValueIsZero
392 #if 0
393  // If this is a truncate of a logical shr, we can truncate it to a smaller
394  // lshr iff we know that the bits we would otherwise be shifting in are
395  // already zeros.
396  uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
397  uint32_t BitWidth = Ty->getScalarSizeInBits();
398  if (MaskedValueIsZero(I->getOperand(0),
399  APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
400  CI->getLimitedValue(BitWidth) < BitWidth) {
401  return CanEvaluateTruncated(I->getOperand(0), Ty);
402  }
403 #endif
404 
405  }
406  }
407 
408  // We can't mutate something that has multiple uses: doing so would
409  // require duplicating the instruction in general, which isn't profitable.
410  if (!I->hasOneUse()) return false;
411 
412  switch (I->getOpcode()) {
413  default: return false;
414  case Instruction::And:
415  case Instruction::Or:
416  case Instruction::Xor:
417  // Bitwise operators can all arbitrarily be arbitrarily evaluated shifted.
418  return canEvaluateShifted(I->getOperand(0), NumBits, IsLeftShift, IC, I) &&
419  canEvaluateShifted(I->getOperand(1), NumBits, IsLeftShift, IC, I);
420 
421  case Instruction::Shl:
422  case Instruction::LShr:
423  return canEvaluateShiftedShift(NumBits, IsLeftShift, I, IC, CxtI);
424 
425  case Instruction::Select: {
426  SelectInst *SI = cast<SelectInst>(I);
427  Value *TrueVal = SI->getTrueValue();
428  Value *FalseVal = SI->getFalseValue();
429  return canEvaluateShifted(TrueVal, NumBits, IsLeftShift, IC, SI) &&
430  canEvaluateShifted(FalseVal, NumBits, IsLeftShift, IC, SI);
431  }
432  case Instruction::PHI: {
433  // We can change a phi if we can change all operands. Note that we never
434  // get into trouble with cyclic PHIs here because we only consider
435  // instructions with a single use.
436  PHINode *PN = cast<PHINode>(I);
437  for (Value *IncValue : PN->incoming_values())
438  if (!canEvaluateShifted(IncValue, NumBits, IsLeftShift, IC, PN))
439  return false;
440  return true;
441  }
442  }
443 }
444 
445 /// Fold OuterShift (InnerShift X, C1), C2.
446 /// See canEvaluateShiftedShift() for the constraints on these instructions.
447 static Value *foldShiftedShift(BinaryOperator *InnerShift, unsigned OuterShAmt,
448  bool IsOuterShl,
449  InstCombiner::BuilderTy &Builder) {
450  bool IsInnerShl = InnerShift->getOpcode() == Instruction::Shl;
451  Type *ShType = InnerShift->getType();
452  unsigned TypeWidth = ShType->getScalarSizeInBits();
453 
454  // We only accept shifts-by-a-constant in canEvaluateShifted().
455  const APInt *C1;
456  match(InnerShift->getOperand(1), m_APInt(C1));
457  unsigned InnerShAmt = C1->getZExtValue();
458 
459  // Change the shift amount and clear the appropriate IR flags.
460  auto NewInnerShift = [&](unsigned ShAmt) {
461  InnerShift->setOperand(1, ConstantInt::get(ShType, ShAmt));
462  if (IsInnerShl) {
463  InnerShift->setHasNoUnsignedWrap(false);
464  InnerShift->setHasNoSignedWrap(false);
465  } else {
466  InnerShift->setIsExact(false);
467  }
468  return InnerShift;
469  };
470 
471  // Two logical shifts in the same direction:
472  // shl (shl X, C1), C2 --> shl X, C1 + C2
473  // lshr (lshr X, C1), C2 --> lshr X, C1 + C2
474  if (IsInnerShl == IsOuterShl) {
475  // If this is an oversized composite shift, then unsigned shifts get 0.
476  if (InnerShAmt + OuterShAmt >= TypeWidth)
477  return Constant::getNullValue(ShType);
478 
479  return NewInnerShift(InnerShAmt + OuterShAmt);
480  }
481 
482  // Equal shift amounts in opposite directions become bitwise 'and':
483  // lshr (shl X, C), C --> and X, C'
484  // shl (lshr X, C), C --> and X, C'
485  if (InnerShAmt == OuterShAmt) {
486  APInt Mask = IsInnerShl
487  ? APInt::getLowBitsSet(TypeWidth, TypeWidth - OuterShAmt)
488  : APInt::getHighBitsSet(TypeWidth, TypeWidth - OuterShAmt);
489  Value *And = Builder.CreateAnd(InnerShift->getOperand(0),
490  ConstantInt::get(ShType, Mask));
491  if (auto *AndI = dyn_cast<Instruction>(And)) {
492  AndI->moveBefore(InnerShift);
493  AndI->takeName(InnerShift);
494  }
495  return And;
496  }
497 
498  assert(InnerShAmt > OuterShAmt &&
499  "Unexpected opposite direction logical shift pair");
500 
501  // In general, we would need an 'and' for this transform, but
502  // canEvaluateShiftedShift() guarantees that the masked-off bits are not used.
503  // lshr (shl X, C1), C2 --> shl X, C1 - C2
504  // shl (lshr X, C1), C2 --> lshr X, C1 - C2
505  return NewInnerShift(InnerShAmt - OuterShAmt);
506 }
507 
508 /// When canEvaluateShifted() returns true for an expression, this function
509 /// inserts the new computation that produces the shifted value.
510 static Value *getShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
511  InstCombiner &IC, const DataLayout &DL) {
512  // We can always evaluate constants shifted.
513  if (Constant *C = dyn_cast<Constant>(V)) {
514  if (isLeftShift)
515  V = IC.Builder.CreateShl(C, NumBits);
516  else
517  V = IC.Builder.CreateLShr(C, NumBits);
518  // If we got a constantexpr back, try to simplify it with TD info.
519  if (auto *C = dyn_cast<Constant>(V))
520  if (auto *FoldedC =
522  V = FoldedC;
523  return V;
524  }
525 
526  Instruction *I = cast<Instruction>(V);
527  IC.Worklist.Add(I);
528 
529  switch (I->getOpcode()) {
530  default: llvm_unreachable("Inconsistency with CanEvaluateShifted");
531  case Instruction::And:
532  case Instruction::Or:
533  case Instruction::Xor:
534  // Bitwise operators can all arbitrarily be arbitrarily evaluated shifted.
535  I->setOperand(
536  0, getShiftedValue(I->getOperand(0), NumBits, isLeftShift, IC, DL));
537  I->setOperand(
538  1, getShiftedValue(I->getOperand(1), NumBits, isLeftShift, IC, DL));
539  return I;
540 
541  case Instruction::Shl:
542  case Instruction::LShr:
543  return foldShiftedShift(cast<BinaryOperator>(I), NumBits, isLeftShift,
544  IC.Builder);
545 
546  case Instruction::Select:
547  I->setOperand(
548  1, getShiftedValue(I->getOperand(1), NumBits, isLeftShift, IC, DL));
549  I->setOperand(
550  2, getShiftedValue(I->getOperand(2), NumBits, isLeftShift, IC, DL));
551  return I;
552  case Instruction::PHI: {
553  // We can change a phi if we can change all operands. Note that we never
554  // get into trouble with cyclic PHIs here because we only consider
555  // instructions with a single use.
556  PHINode *PN = cast<PHINode>(I);
557  for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
558  PN->setIncomingValue(i, getShiftedValue(PN->getIncomingValue(i), NumBits,
559  isLeftShift, IC, DL));
560  return PN;
561  }
562  }
563 }
564 
565 // If this is a bitwise operator or add with a constant RHS we might be able
566 // to pull it through a shift.
568  BinaryOperator *BO) {
569  switch (BO->getOpcode()) {
570  default:
571  return false; // Do not perform transform!
572  case Instruction::Add:
573  return Shift.getOpcode() == Instruction::Shl;
574  case Instruction::Or:
575  case Instruction::Xor:
576  case Instruction::And:
577  return true;
578  }
579 }
580 
582  BinaryOperator &I) {
583  bool isLeftShift = I.getOpcode() == Instruction::Shl;
584 
585  const APInt *Op1C;
586  if (!match(Op1, m_APInt(Op1C)))
587  return nullptr;
588 
589  // See if we can propagate this shift into the input, this covers the trivial
590  // cast of lshr(shl(x,c1),c2) as well as other more complex cases.
591  if (I.getOpcode() != Instruction::AShr &&
592  canEvaluateShifted(Op0, Op1C->getZExtValue(), isLeftShift, *this, &I)) {
593  LLVM_DEBUG(
594  dbgs() << "ICE: GetShiftedValue propagating shift through expression"
595  " to eliminate shift:\n IN: "
596  << *Op0 << "\n SH: " << I << "\n");
597 
598  return replaceInstUsesWith(
599  I, getShiftedValue(Op0, Op1C->getZExtValue(), isLeftShift, *this, DL));
600  }
601 
602  // See if we can simplify any instructions used by the instruction whose sole
603  // purpose is to compute bits we don't care about.
604  unsigned TypeBits = Op0->getType()->getScalarSizeInBits();
605 
606  assert(!Op1C->uge(TypeBits) &&
607  "Shift over the type width should have been removed already");
608 
609  if (Instruction *FoldedShift = foldBinOpIntoSelectOrPhi(I))
610  return FoldedShift;
611 
612  // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
613  if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
614  Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
615  // If 'shift2' is an ashr, we would have to get the sign bit into a funny
616  // place. Don't try to do this transformation in this case. Also, we
617  // require that the input operand is a shift-by-constant so that we have
618  // confidence that the shifts will get folded together. We could do this
619  // xform in more cases, but it is unlikely to be profitable.
620  if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
621  isa<ConstantInt>(TrOp->getOperand(1))) {
622  // Okay, we'll do this xform. Make the shift of shift.
623  Constant *ShAmt =
624  ConstantExpr::getZExt(cast<Constant>(Op1), TrOp->getType());
625  // (shift2 (shift1 & 0x00FF), c2)
626  Value *NSh = Builder.CreateBinOp(I.getOpcode(), TrOp, ShAmt, I.getName());
627 
628  // For logical shifts, the truncation has the effect of making the high
629  // part of the register be zeros. Emulate this by inserting an AND to
630  // clear the top bits as needed. This 'and' will usually be zapped by
631  // other xforms later if dead.
632  unsigned SrcSize = TrOp->getType()->getScalarSizeInBits();
633  unsigned DstSize = TI->getType()->getScalarSizeInBits();
634  APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
635 
636  // The mask we constructed says what the trunc would do if occurring
637  // between the shifts. We want to know the effect *after* the second
638  // shift. We know that it is a logical shift by a constant, so adjust the
639  // mask as appropriate.
640  if (I.getOpcode() == Instruction::Shl)
641  MaskV <<= Op1C->getZExtValue();
642  else {
643  assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
644  MaskV.lshrInPlace(Op1C->getZExtValue());
645  }
646 
647  // shift1 & 0x00FF
648  Value *And = Builder.CreateAnd(NSh,
649  ConstantInt::get(I.getContext(), MaskV),
650  TI->getName());
651 
652  // Return the value truncated to the interesting size.
653  return new TruncInst(And, I.getType());
654  }
655  }
656 
657  if (Op0->hasOneUse()) {
658  if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
659  // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
660  Value *V1, *V2;
661  ConstantInt *CC;
662  switch (Op0BO->getOpcode()) {
663  default: break;
664  case Instruction::Add:
665  case Instruction::And:
666  case Instruction::Or:
667  case Instruction::Xor: {
668  // These operators commute.
669  // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
670  if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
671  match(Op0BO->getOperand(1), m_Shr(m_Value(V1),
672  m_Specific(Op1)))) {
673  Value *YS = // (Y << C)
674  Builder.CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
675  // (X + (Y << C))
676  Value *X = Builder.CreateBinOp(Op0BO->getOpcode(), YS, V1,
677  Op0BO->getOperand(1)->getName());
678  unsigned Op1Val = Op1C->getLimitedValue(TypeBits);
679 
680  APInt Bits = APInt::getHighBitsSet(TypeBits, TypeBits - Op1Val);
682  if (VectorType *VT = dyn_cast<VectorType>(X->getType()))
683  Mask = ConstantVector::getSplat(VT->getNumElements(), Mask);
684  return BinaryOperator::CreateAnd(X, Mask);
685  }
686 
687  // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
688  Value *Op0BOOp1 = Op0BO->getOperand(1);
689  if (isLeftShift && Op0BOOp1->hasOneUse() &&
690  match(Op0BOOp1,
691  m_And(m_OneUse(m_Shr(m_Value(V1), m_Specific(Op1))),
692  m_ConstantInt(CC)))) {
693  Value *YS = // (Y << C)
694  Builder.CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
695  // X & (CC << C)
696  Value *XM = Builder.CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
697  V1->getName()+".mask");
698  return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
699  }
701  }
702 
703  case Instruction::Sub: {
704  // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
705  if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
706  match(Op0BO->getOperand(0), m_Shr(m_Value(V1),
707  m_Specific(Op1)))) {
708  Value *YS = // (Y << C)
709  Builder.CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
710  // (X + (Y << C))
711  Value *X = Builder.CreateBinOp(Op0BO->getOpcode(), V1, YS,
712  Op0BO->getOperand(0)->getName());
713  unsigned Op1Val = Op1C->getLimitedValue(TypeBits);
714 
715  APInt Bits = APInt::getHighBitsSet(TypeBits, TypeBits - Op1Val);
717  if (VectorType *VT = dyn_cast<VectorType>(X->getType()))
718  Mask = ConstantVector::getSplat(VT->getNumElements(), Mask);
719  return BinaryOperator::CreateAnd(X, Mask);
720  }
721 
722  // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
723  if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
724  match(Op0BO->getOperand(0),
725  m_And(m_OneUse(m_Shr(m_Value(V1), m_Value(V2))),
726  m_ConstantInt(CC))) && V2 == Op1) {
727  Value *YS = // (Y << C)
728  Builder.CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
729  // X & (CC << C)
730  Value *XM = Builder.CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
731  V1->getName()+".mask");
732 
733  return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
734  }
735 
736  break;
737  }
738  }
739 
740 
741  // If the operand is a bitwise operator with a constant RHS, and the
742  // shift is the only use, we can pull it out of the shift.
743  const APInt *Op0C;
744  if (match(Op0BO->getOperand(1), m_APInt(Op0C))) {
745  if (canShiftBinOpWithConstantRHS(I, Op0BO)) {
746  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
747  cast<Constant>(Op0BO->getOperand(1)), Op1);
748 
749  Value *NewShift =
750  Builder.CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1);
751  NewShift->takeName(Op0BO);
752 
753  return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
754  NewRHS);
755  }
756  }
757 
758  // If the operand is a subtract with a constant LHS, and the shift
759  // is the only use, we can pull it out of the shift.
760  // This folds (shl (sub C1, X), C2) -> (sub (C1 << C2), (shl X, C2))
761  if (isLeftShift && Op0BO->getOpcode() == Instruction::Sub &&
762  match(Op0BO->getOperand(0), m_APInt(Op0C))) {
763  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
764  cast<Constant>(Op0BO->getOperand(0)), Op1);
765 
766  Value *NewShift = Builder.CreateShl(Op0BO->getOperand(1), Op1);
767  NewShift->takeName(Op0BO);
768 
769  return BinaryOperator::CreateSub(NewRHS, NewShift);
770  }
771  }
772 
773  // If we have a select that conditionally executes some binary operator,
774  // see if we can pull it the select and operator through the shift.
775  //
776  // For example, turning:
777  // shl (select C, (add X, C1), X), C2
778  // Into:
779  // Y = shl X, C2
780  // select C, (add Y, C1 << C2), Y
781  Value *Cond;
782  BinaryOperator *TBO;
783  Value *FalseVal;
784  if (match(Op0, m_Select(m_Value(Cond), m_OneUse(m_BinOp(TBO)),
785  m_Value(FalseVal)))) {
786  const APInt *C;
787  if (!isa<Constant>(FalseVal) && TBO->getOperand(0) == FalseVal &&
788  match(TBO->getOperand(1), m_APInt(C)) &&
790  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
791  cast<Constant>(TBO->getOperand(1)), Op1);
792 
793  Value *NewShift =
794  Builder.CreateBinOp(I.getOpcode(), FalseVal, Op1);
795  Value *NewOp = Builder.CreateBinOp(TBO->getOpcode(), NewShift,
796  NewRHS);
797  return SelectInst::Create(Cond, NewOp, NewShift);
798  }
799  }
800 
801  BinaryOperator *FBO;
802  Value *TrueVal;
803  if (match(Op0, m_Select(m_Value(Cond), m_Value(TrueVal),
804  m_OneUse(m_BinOp(FBO))))) {
805  const APInt *C;
806  if (!isa<Constant>(TrueVal) && FBO->getOperand(0) == TrueVal &&
807  match(FBO->getOperand(1), m_APInt(C)) &&
809  Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
810  cast<Constant>(FBO->getOperand(1)), Op1);
811 
812  Value *NewShift =
813  Builder.CreateBinOp(I.getOpcode(), TrueVal, Op1);
814  Value *NewOp = Builder.CreateBinOp(FBO->getOpcode(), NewShift,
815  NewRHS);
816  return SelectInst::Create(Cond, NewShift, NewOp);
817  }
818  }
819  }
820 
821  return nullptr;
822 }
823 
825  const SimplifyQuery Q = SQ.getWithInstruction(&I);
826 
827  if (Value *V = SimplifyShlInst(I.getOperand(0), I.getOperand(1),
828  I.hasNoSignedWrap(), I.hasNoUnsignedWrap(), Q))
829  return replaceInstUsesWith(I, V);
830 
831  if (Instruction *X = foldVectorBinop(I))
832  return X;
833 
834  if (Instruction *V = commonShiftTransforms(I))
835  return V;
836 
837  if (Instruction *V = dropRedundantMaskingOfLeftShiftInput(&I, Q, Builder))
838  return V;
839 
840  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
841  Type *Ty = I.getType();
842  unsigned BitWidth = Ty->getScalarSizeInBits();
843 
844  const APInt *ShAmtAPInt;
845  if (match(Op1, m_APInt(ShAmtAPInt))) {
846  unsigned ShAmt = ShAmtAPInt->getZExtValue();
847 
848  // shl (zext X), ShAmt --> zext (shl X, ShAmt)
849  // This is only valid if X would have zeros shifted out.
850  Value *X;
851  if (match(Op0, m_OneUse(m_ZExt(m_Value(X))))) {
852  unsigned SrcWidth = X->getType()->getScalarSizeInBits();
853  if (ShAmt < SrcWidth &&
854  MaskedValueIsZero(X, APInt::getHighBitsSet(SrcWidth, ShAmt), 0, &I))
855  return new ZExtInst(Builder.CreateShl(X, ShAmt), Ty);
856  }
857 
858  // (X >> C) << C --> X & (-1 << C)
859  if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1)))) {
860  APInt Mask(APInt::getHighBitsSet(BitWidth, BitWidth - ShAmt));
861  return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, Mask));
862  }
863 
864  // FIXME: we do not yet transform non-exact shr's. The backend (DAGCombine)
865  // needs a few fixes for the rotate pattern recognition first.
866  const APInt *ShOp1;
867  if (match(Op0, m_Exact(m_Shr(m_Value(X), m_APInt(ShOp1))))) {
868  unsigned ShrAmt = ShOp1->getZExtValue();
869  if (ShrAmt < ShAmt) {
870  // If C1 < C2: (X >>?,exact C1) << C2 --> X << (C2 - C1)
871  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShrAmt);
872  auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
873  NewShl->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
874  NewShl->setHasNoSignedWrap(I.hasNoSignedWrap());
875  return NewShl;
876  }
877  if (ShrAmt > ShAmt) {
878  // If C1 > C2: (X >>?exact C1) << C2 --> X >>?exact (C1 - C2)
879  Constant *ShiftDiff = ConstantInt::get(Ty, ShrAmt - ShAmt);
880  auto *NewShr = BinaryOperator::Create(
881  cast<BinaryOperator>(Op0)->getOpcode(), X, ShiftDiff);
882  NewShr->setIsExact(true);
883  return NewShr;
884  }
885  }
886 
887  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShOp1)))) {
888  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
889  // Oversized shifts are simplified to zero in InstSimplify.
890  if (AmtSum < BitWidth)
891  // (X << C1) << C2 --> X << (C1 + C2)
892  return BinaryOperator::CreateShl(X, ConstantInt::get(Ty, AmtSum));
893  }
894 
895  // If the shifted-out value is known-zero, then this is a NUW shift.
896  if (!I.hasNoUnsignedWrap() &&
897  MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, ShAmt), 0, &I)) {
899  return &I;
900  }
901 
902  // If the shifted-out value is all signbits, then this is a NSW shift.
903  if (!I.hasNoSignedWrap() && ComputeNumSignBits(Op0, 0, &I) > ShAmt) {
904  I.setHasNoSignedWrap();
905  return &I;
906  }
907  }
908 
909  // Transform (x >> y) << y to x & (-1 << y)
910  // Valid for any type of right-shift.
911  Value *X;
912  if (match(Op0, m_OneUse(m_Shr(m_Value(X), m_Specific(Op1))))) {
913  Constant *AllOnes = ConstantInt::getAllOnesValue(Ty);
914  Value *Mask = Builder.CreateShl(AllOnes, Op1);
915  return BinaryOperator::CreateAnd(Mask, X);
916  }
917 
918  Constant *C1;
919  if (match(Op1, m_Constant(C1))) {
920  Constant *C2;
921  Value *X;
922  // (C2 << X) << C1 --> (C2 << C1) << X
923  if (match(Op0, m_OneUse(m_Shl(m_Constant(C2), m_Value(X)))))
924  return BinaryOperator::CreateShl(ConstantExpr::getShl(C2, C1), X);
925 
926  // (X * C2) << C1 --> X * (C2 << C1)
927  if (match(Op0, m_Mul(m_Value(X), m_Constant(C2))))
929 
930  // shl (zext i1 X), C1 --> select (X, 1 << C1, 0)
931  if (match(Op0, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
932  auto *NewC = ConstantExpr::getShl(ConstantInt::get(Ty, 1), C1);
933  return SelectInst::Create(X, NewC, ConstantInt::getNullValue(Ty));
934  }
935  }
936 
937  // (1 << (C - x)) -> ((1 << C) >> x) if C is bitwidth - 1
938  if (match(Op0, m_One()) &&
939  match(Op1, m_Sub(m_SpecificInt(BitWidth - 1), m_Value(X))))
940  return BinaryOperator::CreateLShr(
941  ConstantInt::get(Ty, APInt::getSignMask(BitWidth)), X);
942 
943  return nullptr;
944 }
945 
947  if (Value *V = SimplifyLShrInst(I.getOperand(0), I.getOperand(1), I.isExact(),
948  SQ.getWithInstruction(&I)))
949  return replaceInstUsesWith(I, V);
950 
951  if (Instruction *X = foldVectorBinop(I))
952  return X;
953 
954  if (Instruction *R = commonShiftTransforms(I))
955  return R;
956 
957  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
958  Type *Ty = I.getType();
959  const APInt *ShAmtAPInt;
960  if (match(Op1, m_APInt(ShAmtAPInt))) {
961  unsigned ShAmt = ShAmtAPInt->getZExtValue();
962  unsigned BitWidth = Ty->getScalarSizeInBits();
963  auto *II = dyn_cast<IntrinsicInst>(Op0);
964  if (II && isPowerOf2_32(BitWidth) && Log2_32(BitWidth) == ShAmt &&
965  (II->getIntrinsicID() == Intrinsic::ctlz ||
966  II->getIntrinsicID() == Intrinsic::cttz ||
967  II->getIntrinsicID() == Intrinsic::ctpop)) {
968  // ctlz.i32(x)>>5 --> zext(x == 0)
969  // cttz.i32(x)>>5 --> zext(x == 0)
970  // ctpop.i32(x)>>5 --> zext(x == -1)
971  bool IsPop = II->getIntrinsicID() == Intrinsic::ctpop;
972  Constant *RHS = ConstantInt::getSigned(Ty, IsPop ? -1 : 0);
973  Value *Cmp = Builder.CreateICmpEQ(II->getArgOperand(0), RHS);
974  return new ZExtInst(Cmp, Ty);
975  }
976 
977  Value *X;
978  const APInt *ShOp1;
979  if (match(Op0, m_Shl(m_Value(X), m_APInt(ShOp1))) && ShOp1->ult(BitWidth)) {
980  if (ShOp1->ult(ShAmt)) {
981  unsigned ShlAmt = ShOp1->getZExtValue();
982  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShlAmt);
983  if (cast<BinaryOperator>(Op0)->hasNoUnsignedWrap()) {
984  // (X <<nuw C1) >>u C2 --> X >>u (C2 - C1)
985  auto *NewLShr = BinaryOperator::CreateLShr(X, ShiftDiff);
986  NewLShr->setIsExact(I.isExact());
987  return NewLShr;
988  }
989  // (X << C1) >>u C2 --> (X >>u (C2 - C1)) & (-1 >> C2)
990  Value *NewLShr = Builder.CreateLShr(X, ShiftDiff, "", I.isExact());
991  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
992  return BinaryOperator::CreateAnd(NewLShr, ConstantInt::get(Ty, Mask));
993  }
994  if (ShOp1->ugt(ShAmt)) {
995  unsigned ShlAmt = ShOp1->getZExtValue();
996  Constant *ShiftDiff = ConstantInt::get(Ty, ShlAmt - ShAmt);
997  if (cast<BinaryOperator>(Op0)->hasNoUnsignedWrap()) {
998  // (X <<nuw C1) >>u C2 --> X <<nuw (C1 - C2)
999  auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
1000  NewShl->setHasNoUnsignedWrap(true);
1001  return NewShl;
1002  }
1003  // (X << C1) >>u C2 --> X << (C1 - C2) & (-1 >> C2)
1004  Value *NewShl = Builder.CreateShl(X, ShiftDiff);
1005  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
1006  return BinaryOperator::CreateAnd(NewShl, ConstantInt::get(Ty, Mask));
1007  }
1008  assert(*ShOp1 == ShAmt);
1009  // (X << C) >>u C --> X & (-1 >>u C)
1010  APInt Mask(APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt));
1011  return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, Mask));
1012  }
1013 
1014  if (match(Op0, m_OneUse(m_ZExt(m_Value(X)))) &&
1015  (!Ty->isIntegerTy() || shouldChangeType(Ty, X->getType()))) {
1016  assert(ShAmt < X->getType()->getScalarSizeInBits() &&
1017  "Big shift not simplified to zero?");
1018  // lshr (zext iM X to iN), C --> zext (lshr X, C) to iN
1019  Value *NewLShr = Builder.CreateLShr(X, ShAmt);
1020  return new ZExtInst(NewLShr, Ty);
1021  }
1022 
1023  if (match(Op0, m_SExt(m_Value(X))) &&
1024  (!Ty->isIntegerTy() || shouldChangeType(Ty, X->getType()))) {
1025  // Are we moving the sign bit to the low bit and widening with high zeros?
1026  unsigned SrcTyBitWidth = X->getType()->getScalarSizeInBits();
1027  if (ShAmt == BitWidth - 1) {
1028  // lshr (sext i1 X to iN), N-1 --> zext X to iN
1029  if (SrcTyBitWidth == 1)
1030  return new ZExtInst(X, Ty);
1031 
1032  // lshr (sext iM X to iN), N-1 --> zext (lshr X, M-1) to iN
1033  if (Op0->hasOneUse()) {
1034  Value *NewLShr = Builder.CreateLShr(X, SrcTyBitWidth - 1);
1035  return new ZExtInst(NewLShr, Ty);
1036  }
1037  }
1038 
1039  // lshr (sext iM X to iN), N-M --> zext (ashr X, min(N-M, M-1)) to iN
1040  if (ShAmt == BitWidth - SrcTyBitWidth && Op0->hasOneUse()) {
1041  // The new shift amount can't be more than the narrow source type.
1042  unsigned NewShAmt = std::min(ShAmt, SrcTyBitWidth - 1);
1043  Value *AShr = Builder.CreateAShr(X, NewShAmt);
1044  return new ZExtInst(AShr, Ty);
1045  }
1046  }
1047 
1048  if (match(Op0, m_LShr(m_Value(X), m_APInt(ShOp1)))) {
1049  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
1050  // Oversized shifts are simplified to zero in InstSimplify.
1051  if (AmtSum < BitWidth)
1052  // (X >>u C1) >>u C2 --> X >>u (C1 + C2)
1053  return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
1054  }
1055 
1056  // If the shifted-out value is known-zero, then this is an exact shift.
1057  if (!I.isExact() &&
1058  MaskedValueIsZero(Op0, APInt::getLowBitsSet(BitWidth, ShAmt), 0, &I)) {
1059  I.setIsExact();
1060  return &I;
1061  }
1062  }
1063 
1064  // Transform (x << y) >> y to x & (-1 >> y)
1065  Value *X;
1066  if (match(Op0, m_OneUse(m_Shl(m_Value(X), m_Specific(Op1))))) {
1067  Constant *AllOnes = ConstantInt::getAllOnesValue(Ty);
1068  Value *Mask = Builder.CreateLShr(AllOnes, Op1);
1069  return BinaryOperator::CreateAnd(Mask, X);
1070  }
1071 
1072  return nullptr;
1073 }
1074 
1075 Instruction *
1077  BinaryOperator &OldAShr) {
1078  assert(OldAShr.getOpcode() == Instruction::AShr &&
1079  "Must be called with arithmetic right-shift instruction only.");
1080 
1081  // Check that constant C is a splat of the element-wise bitwidth of V.
1082  auto BitWidthSplat = [](Constant *C, Value *V) {
1083  return match(
1084  C, m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_EQ,
1086  V->getType()->getScalarSizeInBits())));
1087  };
1088 
1089  // It should look like variable-length sign-extension on the outside:
1090  // (Val << (bitwidth(Val)-Nbits)) a>> (bitwidth(Val)-Nbits)
1091  Value *NBits;
1092  Instruction *MaybeTrunc;
1093  Constant *C1, *C2;
1094  if (!match(&OldAShr,
1095  m_AShr(m_Shl(m_Instruction(MaybeTrunc),
1097  m_ZExtOrSelf(m_Value(NBits))))),
1099  m_ZExtOrSelf(m_Deferred(NBits)))))) ||
1100  !BitWidthSplat(C1, &OldAShr) || !BitWidthSplat(C2, &OldAShr))
1101  return nullptr;
1102 
1103  // There may or may not be a truncation after outer two shifts.
1104  Instruction *HighBitExtract;
1105  match(MaybeTrunc, m_TruncOrSelf(m_Instruction(HighBitExtract)));
1106  bool HadTrunc = MaybeTrunc != HighBitExtract;
1107 
1108  // And finally, the innermost part of the pattern must be a right-shift.
1109  Value *X, *NumLowBitsToSkip;
1110  if (!match(HighBitExtract, m_Shr(m_Value(X), m_Value(NumLowBitsToSkip))))
1111  return nullptr;
1112 
1113  // Said right-shift must extract high NBits bits - C0 must be it's bitwidth.
1114  Constant *C0;
1115  if (!match(NumLowBitsToSkip,
1116  m_ZExtOrSelf(
1117  m_Sub(m_Constant(C0), m_ZExtOrSelf(m_Specific(NBits))))) ||
1118  !BitWidthSplat(C0, HighBitExtract))
1119  return nullptr;
1120 
1121  // Since the NBits is identical for all shifts, if the outermost and
1122  // innermost shifts are identical, then outermost shifts are redundant.
1123  // If we had truncation, do keep it though.
1124  if (HighBitExtract->getOpcode() == OldAShr.getOpcode())
1125  return replaceInstUsesWith(OldAShr, MaybeTrunc);
1126 
1127  // Else, if there was a truncation, then we need to ensure that one
1128  // instruction will go away.
1129  if (HadTrunc && !match(&OldAShr, m_c_BinOp(m_OneUse(m_Value()), m_Value())))
1130  return nullptr;
1131 
1132  // Finally, bypass two innermost shifts, and perform the outermost shift on
1133  // the operands of the innermost shift.
1134  Instruction *NewAShr =
1135  BinaryOperator::Create(OldAShr.getOpcode(), X, NumLowBitsToSkip);
1136  NewAShr->copyIRFlags(HighBitExtract); // We can preserve 'exact'-ness.
1137  if (!HadTrunc)
1138  return NewAShr;
1139 
1140  Builder.Insert(NewAShr);
1141  return TruncInst::CreateTruncOrBitCast(NewAShr, OldAShr.getType());
1142 }
1143 
1145  if (Value *V = SimplifyAShrInst(I.getOperand(0), I.getOperand(1), I.isExact(),
1146  SQ.getWithInstruction(&I)))
1147  return replaceInstUsesWith(I, V);
1148 
1149  if (Instruction *X = foldVectorBinop(I))
1150  return X;
1151 
1152  if (Instruction *R = commonShiftTransforms(I))
1153  return R;
1154 
1155  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1156  Type *Ty = I.getType();
1157  unsigned BitWidth = Ty->getScalarSizeInBits();
1158  const APInt *ShAmtAPInt;
1159  if (match(Op1, m_APInt(ShAmtAPInt)) && ShAmtAPInt->ult(BitWidth)) {
1160  unsigned ShAmt = ShAmtAPInt->getZExtValue();
1161 
1162  // If the shift amount equals the difference in width of the destination
1163  // and source scalar types:
1164  // ashr (shl (zext X), C), C --> sext X
1165  Value *X;
1166  if (match(Op0, m_Shl(m_ZExt(m_Value(X)), m_Specific(Op1))) &&
1167  ShAmt == BitWidth - X->getType()->getScalarSizeInBits())
1168  return new SExtInst(X, Ty);
1169 
1170  // We can't handle (X << C1) >>s C2. It shifts arbitrary bits in. However,
1171  // we can handle (X <<nsw C1) >>s C2 since it only shifts in sign bits.
1172  const APInt *ShOp1;
1173  if (match(Op0, m_NSWShl(m_Value(X), m_APInt(ShOp1))) &&
1174  ShOp1->ult(BitWidth)) {
1175  unsigned ShlAmt = ShOp1->getZExtValue();
1176  if (ShlAmt < ShAmt) {
1177  // (X <<nsw C1) >>s C2 --> X >>s (C2 - C1)
1178  Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShlAmt);
1179  auto *NewAShr = BinaryOperator::CreateAShr(X, ShiftDiff);
1180  NewAShr->setIsExact(I.isExact());
1181  return NewAShr;
1182  }
1183  if (ShlAmt > ShAmt) {
1184  // (X <<nsw C1) >>s C2 --> X <<nsw (C1 - C2)
1185  Constant *ShiftDiff = ConstantInt::get(Ty, ShlAmt - ShAmt);
1186  auto *NewShl = BinaryOperator::Create(Instruction::Shl, X, ShiftDiff);
1187  NewShl->setHasNoSignedWrap(true);
1188  return NewShl;
1189  }
1190  }
1191 
1192  if (match(Op0, m_AShr(m_Value(X), m_APInt(ShOp1))) &&
1193  ShOp1->ult(BitWidth)) {
1194  unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
1195  // Oversized arithmetic shifts replicate the sign bit.
1196  AmtSum = std::min(AmtSum, BitWidth - 1);
1197  // (X >>s C1) >>s C2 --> X >>s (C1 + C2)
1198  return BinaryOperator::CreateAShr(X, ConstantInt::get(Ty, AmtSum));
1199  }
1200 
1201  if (match(Op0, m_OneUse(m_SExt(m_Value(X)))) &&
1202  (Ty->isVectorTy() || shouldChangeType(Ty, X->getType()))) {
1203  // ashr (sext X), C --> sext (ashr X, C')
1204  Type *SrcTy = X->getType();
1205  ShAmt = std::min(ShAmt, SrcTy->getScalarSizeInBits() - 1);
1206  Value *NewSh = Builder.CreateAShr(X, ConstantInt::get(SrcTy, ShAmt));
1207  return new SExtInst(NewSh, Ty);
1208  }
1209 
1210  // If the shifted-out value is known-zero, then this is an exact shift.
1211  if (!I.isExact() &&
1212  MaskedValueIsZero(Op0, APInt::getLowBitsSet(BitWidth, ShAmt), 0, &I)) {
1213  I.setIsExact();
1214  return &I;
1215  }
1216  }
1217 
1218  if (Instruction *R = foldVariableSignZeroExtensionOfVariableHighBitExtract(I))
1219  return R;
1220 
1221  // See if we can turn a signed shr into an unsigned shr.
1222  if (MaskedValueIsZero(Op0, APInt::getSignMask(BitWidth), 0, &I))
1223  return BinaryOperator::CreateLShr(Op0, Op1);
1224 
1225  return nullptr;
1226 }
cst_pred_ty< icmp_pred_with_threshold > m_SpecificInt_ICMP(ICmpInst::Predicate Predicate, const APInt &Threshold)
Match an integer or vector with every element comparing &#39;pred&#39; (eg/ne/...) to Threshold.
Definition: PatternMatch.h:494
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:874
uint64_t CallInst * C
BinOpPred_match< LHS, RHS, is_right_shift_op > m_Shr(const LHS &L, const RHS &R)
Matches logical shift operations.
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:112
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:70
class_match< UndefValue > m_Undef()
Match an arbitrary undef constant.
Definition: PatternMatch.h:86
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
uint64_t getZExtValue() const
Get zero extended value.
Definition: APInt.h:1571
ThreeOps_match< Cond, LHS, RHS, Instruction::Select > m_Select(const Cond &C, const LHS &L, const RHS &R)
Matches SelectInst.
BinaryOp_match< LHS, RHS, Instruction::Sub > m_Sub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:771
This class represents lattice values for constants.
Definition: AllocatorList.h:23
SimplifyQuery getWithInstruction(Instruction *I) const
BinaryOps getOpcode() const
Definition: InstrTypes.h:402
static Instruction * dropRedundantMaskingOfLeftShiftInput(BinaryOperator *OuterShift, const SimplifyQuery &Q, InstCombiner::BuilderTy &Builder)
BinaryOp_match< LHS, RHS, Instruction::SRem > m_SRem(const LHS &L, const RHS &R)
Definition: PatternMatch.h:862
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:826
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:647
class_match< Constant > m_Constant()
Match an arbitrary Constant and ignore it.
Definition: PatternMatch.h:89
const Value * getTrueValue() const
BinaryOp_match< LHS, RHS, Instruction::AShr > m_AShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:904
static SelectInst * Create(Value *C, Value *S1, Value *S2, const Twine &NameStr="", Instruction *InsertBefore=nullptr, Instruction *MDFrom=nullptr)
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:743
void Add(Instruction *I)
Add - Add the specified instruction to the worklist if it isn&#39;t already in it.
static Instruction * reassociateShiftAmtsOfTwoSameDirectionShifts(BinaryOperator *Sh0, const SimplifyQuery &SQ, InstCombiner::BuilderTy &Builder)
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.
static Constant * getSub(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2261
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:230
void copyIRFlags(const Value *V, bool IncludeWrapFlags=true)
Convenience method to copy supported exact, fast-math, and (optionally) wrapping flags from V to this...
AnyBinaryOp_match< LHS, RHS, true > m_c_BinOp(const LHS &L, const RHS &R)
Matches a BinaryOperator with LHS and RHS in either order.
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:289
Value * SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, const SimplifyQuery &Q)
Given operands for a LShr, fold the result or return null.
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:47
match_combine_or< CastClass_match< OpTy, Instruction::ZExt >, OpTy > m_ZExtOrSelf(const OpTy &Op)
BinaryOp_match< LHS, RHS, Instruction::Xor > m_Xor(const LHS &L, const RHS &R)
Definition: PatternMatch.h:886
This class represents the LLVM &#39;select&#39; instruction.
Instruction * commonShiftTransforms(BinaryOperator &I)
Exact_match< T > m_Exact(const T &SubPattern)
static Constant * getLShr(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2328
static Optional< unsigned > getOpcode(ArrayRef< VPValue *> Values)
Returns the opcode of Values or ~0 if they do not all agree.
Definition: VPlanSLP.cpp:196
CastClass_match< OpTy, Instruction::Trunc > m_Trunc(const OpTy &Op)
Matches Trunc.
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:197
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:977
BinaryOp_match< LHS, RHS, Instruction::Add > m_Add(const LHS &L, const RHS &R)
Definition: PatternMatch.h:759
static bool canShiftBinOpWithConstantRHS(BinaryOperator &Shift, BinaryOperator *BO)
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:1696
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:246
match_combine_or< LTy, RTy > m_CombineOr(const LTy &L, const RTy &R)
Combine two pattern matchers matching L || R.
Definition: PatternMatch.h:142
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:81
Instruction * foldVariableSignZeroExtensionOfVariableHighBitExtract(BinaryOperator &OldAShr)
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:137
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:125
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:203
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:412
match_combine_or< CastClass_match< OpTy, Instruction::Trunc >, OpTy > m_TruncOrSelf(const OpTy &Op)
Type * getExtendedType() const
Given scalar/vector integer type, returns a type with elements twice as wide as in the original type...
Definition: DerivedTypes.h:611
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:291
This class represents a truncation of integer types.
static Constant * replaceUndefsWith(Constant *C, Constant *Replacement)
Value * getOperand(unsigned i) const
Definition: User.h:169
static APInt getHighBitsSet(unsigned numBits, unsigned hiBitsSet)
Get a value with high bits set.
Definition: APInt.h:635
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:61
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:898
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:194
constexpr bool isPowerOf2_32(uint32_t Value)
Return true if the argument is a power of two > 0.
Definition: MathExtras.h:465
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1184
This is an important base class in LLVM.
Definition: Constant.h:41
BinaryOp_match< LHS, RHS, Instruction::And, true > m_c_And(const LHS &L, const RHS &R)
Matches an And with LHS and RHS in either order.
static unsigned getScalarSizeInBits(Type *Ty)
specific_intval m_SpecificInt(APInt V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:664
cst_pred_ty< is_all_ones > m_AllOnes()
Match an integer or vector with all bits set.
Definition: PatternMatch.h:336
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:587
Value * SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, const SimplifyQuery &Q)
Given operands for an Add, fold the result or return null.
BinaryOp_match< LHS, RHS, Instruction::Shl > m_Shl(const LHS &L, const RHS &R)
Definition: PatternMatch.h:892
constexpr double e
Definition: MathExtras.h:57
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:73
static Constant * getNot(Constant *C)
Definition: Constants.cpp:2244
static Constant * getAllOnesValue(Type *Ty)
Definition: Constants.cpp:343
Instruction * visitLShr(BinaryOperator &I)
static bool hasNoUnsignedWrap(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.
deferredval_ty< Value > m_Deferred(Value *const &V)
A commutative-friendly version of m_Specific().
Definition: PatternMatch.h:600
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:50
static APInt getSignMask(unsigned BitWidth)
Get the SignMask for a specific bit width.
Definition: APInt.h:554
static Constant * getSplat(unsigned NumElts, Constant *Elt)
Return a ConstantVector with the specified constant in each element.
Definition: Constants.cpp:1150
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:250
This is the shared class of boolean and integer constants.
Definition: Constants.h:83
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type...
Definition: Type.cpp:134
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
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 * getTrunc(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1668
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:653
static ConstantInt * getSigned(IntegerType *Ty, int64_t V)
Return a ConstantInt with the specified value for the specified type.
Definition: Constants.cpp:667
unsigned getNumIncomingValues() const
Return the number of incoming edges.
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1292
void setOperand(unsigned i, Value *Val)
Definition: User.h:174
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:585
Class to represent vector types.
Definition: DerivedTypes.h:432
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.
BinOpPred_match< LHS, RHS, is_shift_op > m_Shift(const LHS &L, const RHS &R)
Matches shift operations.
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1207
const Value * getFalseValue() const
static Constant * getZExtOrBitCast(Constant *C, Type *Ty)
Definition: Constants.cpp:1600
bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth=0, const Instruction *CxtI=nullptr) const
static CastInst * Create(Instruction::CastOps, Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Provides a way to construct any of the CastInst subclasses using an opcode instead of the subclass&#39;s ...
bool ugt(const APInt &RHS) const
Unsigned greather than comparison.
Definition: APInt.h:1254
static CastInst * CreateTruncOrBitCast(Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Create a Trunc or BitCast cast instruction.
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:481
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
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:961
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:332
static Constant * getShl(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2321
bool isLogicalShift() const
Return true if this is a logical shift left or a logical shift right.
Definition: Instruction.h:165
bool hasNoUnsignedWrap() const
Determine whether the no unsigned wrap flag is set.
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1268
InstTy * Insert(InstTy *I, const Twine &Name="") const
Insert and return the specified instruction.
Definition: IRBuilder.h:830
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:74
This file provides internal interfaces used to implement the InstCombine.
cst_pred_ty< is_one > m_One()
Match an integer 1 or a vector with all elements equal to 1.
Definition: PatternMatch.h:382
#define LLVM_FALLTHROUGH
LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
Definition: Compiler.h:273
std::underlying_type< E >::type Mask()
Get a bitmask with 1s in all places up to the high-order bit of E&#39;s largest value.
Definition: BitmaskEnum.h:80
Value * CreateLShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1228
Value * SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, const SimplifyQuery &Q)
Given operands for a Sub, fold the result or return null.
match_combine_and< LTy, RTy > m_CombineAnd(const LTy &L, const RTy &R)
Combine two pattern matchers matching L && R.
Definition: PatternMatch.h:148
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:433
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:122
op_range incoming_values()
Instruction * FoldShiftByConstant(Value *Op0, Constant *Op1, BinaryOperator &I)
static Constant * get(ArrayRef< Constant *> V)
Definition: Constants.cpp:1110
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:558
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:43
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:1837