LLVM  10.0.0svn
InstCombineCasts.cpp
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1 //===- InstCombineCasts.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 visit functions for cast operations.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "InstCombineInternal.h"
14 #include "llvm/ADT/SetVector.h"
17 #include "llvm/IR/DataLayout.h"
18 #include "llvm/IR/DIBuilder.h"
19 #include "llvm/IR/PatternMatch.h"
20 #include "llvm/Support/KnownBits.h"
21 using namespace llvm;
22 using namespace PatternMatch;
23 
24 #define DEBUG_TYPE "instcombine"
25 
26 /// Analyze 'Val', seeing if it is a simple linear expression.
27 /// If so, decompose it, returning some value X, such that Val is
28 /// X*Scale+Offset.
29 ///
30 static Value *decomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
31  uint64_t &Offset) {
32  if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
33  Offset = CI->getZExtValue();
34  Scale = 0;
35  return ConstantInt::get(Val->getType(), 0);
36  }
37 
38  if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
39  // Cannot look past anything that might overflow.
41  if (OBI && !OBI->hasNoUnsignedWrap() && !OBI->hasNoSignedWrap()) {
42  Scale = 1;
43  Offset = 0;
44  return Val;
45  }
46 
47  if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
48  if (I->getOpcode() == Instruction::Shl) {
49  // This is a value scaled by '1 << the shift amt'.
50  Scale = UINT64_C(1) << RHS->getZExtValue();
51  Offset = 0;
52  return I->getOperand(0);
53  }
54 
55  if (I->getOpcode() == Instruction::Mul) {
56  // This value is scaled by 'RHS'.
57  Scale = RHS->getZExtValue();
58  Offset = 0;
59  return I->getOperand(0);
60  }
61 
62  if (I->getOpcode() == Instruction::Add) {
63  // We have X+C. Check to see if we really have (X*C2)+C1,
64  // where C1 is divisible by C2.
65  unsigned SubScale;
66  Value *SubVal =
67  decomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
68  Offset += RHS->getZExtValue();
69  Scale = SubScale;
70  return SubVal;
71  }
72  }
73  }
74 
75  // Otherwise, we can't look past this.
76  Scale = 1;
77  Offset = 0;
78  return Val;
79 }
80 
81 /// If we find a cast of an allocation instruction, try to eliminate the cast by
82 /// moving the type information into the alloc.
83 Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
84  AllocaInst &AI) {
85  PointerType *PTy = cast<PointerType>(CI.getType());
86 
87  BuilderTy AllocaBuilder(Builder);
88  AllocaBuilder.SetInsertPoint(&AI);
89 
90  // Get the type really allocated and the type casted to.
91  Type *AllocElTy = AI.getAllocatedType();
92  Type *CastElTy = PTy->getElementType();
93  if (!AllocElTy->isSized() || !CastElTy->isSized()) return nullptr;
94 
95  unsigned AllocElTyAlign = DL.getABITypeAlignment(AllocElTy);
96  unsigned CastElTyAlign = DL.getABITypeAlignment(CastElTy);
97  if (CastElTyAlign < AllocElTyAlign) return nullptr;
98 
99  // If the allocation has multiple uses, only promote it if we are strictly
100  // increasing the alignment of the resultant allocation. If we keep it the
101  // same, we open the door to infinite loops of various kinds.
102  if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return nullptr;
103 
104  uint64_t AllocElTySize = DL.getTypeAllocSize(AllocElTy);
105  uint64_t CastElTySize = DL.getTypeAllocSize(CastElTy);
106  if (CastElTySize == 0 || AllocElTySize == 0) return nullptr;
107 
108  // If the allocation has multiple uses, only promote it if we're not
109  // shrinking the amount of memory being allocated.
110  uint64_t AllocElTyStoreSize = DL.getTypeStoreSize(AllocElTy);
111  uint64_t CastElTyStoreSize = DL.getTypeStoreSize(CastElTy);
112  if (!AI.hasOneUse() && CastElTyStoreSize < AllocElTyStoreSize) return nullptr;
113 
114  // See if we can satisfy the modulus by pulling a scale out of the array
115  // size argument.
116  unsigned ArraySizeScale;
117  uint64_t ArrayOffset;
118  Value *NumElements = // See if the array size is a decomposable linear expr.
119  decomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
120 
121  // If we can now satisfy the modulus, by using a non-1 scale, we really can
122  // do the xform.
123  if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
124  (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return nullptr;
125 
126  unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
127  Value *Amt = nullptr;
128  if (Scale == 1) {
129  Amt = NumElements;
130  } else {
131  Amt = ConstantInt::get(AI.getArraySize()->getType(), Scale);
132  // Insert before the alloca, not before the cast.
133  Amt = AllocaBuilder.CreateMul(Amt, NumElements);
134  }
135 
136  if (uint64_t Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
138  Offset, true);
139  Amt = AllocaBuilder.CreateAdd(Amt, Off);
140  }
141 
142  AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
144  New->takeName(&AI);
146 
147  // If the allocation has multiple real uses, insert a cast and change all
148  // things that used it to use the new cast. This will also hack on CI, but it
149  // will die soon.
150  if (!AI.hasOneUse()) {
151  // New is the allocation instruction, pointer typed. AI is the original
152  // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
153  Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
154  replaceInstUsesWith(AI, NewCast);
155  }
156  return replaceInstUsesWith(CI, New);
157 }
158 
159 /// Given an expression that CanEvaluateTruncated or CanEvaluateSExtd returns
160 /// true for, actually insert the code to evaluate the expression.
161 Value *InstCombiner::EvaluateInDifferentType(Value *V, Type *Ty,
162  bool isSigned) {
163  if (Constant *C = dyn_cast<Constant>(V)) {
164  C = ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
165  // If we got a constantexpr back, try to simplify it with DL info.
166  if (Constant *FoldedC = ConstantFoldConstant(C, DL, &TLI))
167  C = FoldedC;
168  return C;
169  }
170 
171  // Otherwise, it must be an instruction.
172  Instruction *I = cast<Instruction>(V);
173  Instruction *Res = nullptr;
174  unsigned Opc = I->getOpcode();
175  switch (Opc) {
176  case Instruction::Add:
177  case Instruction::Sub:
178  case Instruction::Mul:
179  case Instruction::And:
180  case Instruction::Or:
181  case Instruction::Xor:
182  case Instruction::AShr:
183  case Instruction::LShr:
184  case Instruction::Shl:
185  case Instruction::UDiv:
186  case Instruction::URem: {
187  Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
188  Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
189  Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
190  break;
191  }
192  case Instruction::Trunc:
193  case Instruction::ZExt:
194  case Instruction::SExt:
195  // If the source type of the cast is the type we're trying for then we can
196  // just return the source. There's no need to insert it because it is not
197  // new.
198  if (I->getOperand(0)->getType() == Ty)
199  return I->getOperand(0);
200 
201  // Otherwise, must be the same type of cast, so just reinsert a new one.
202  // This also handles the case of zext(trunc(x)) -> zext(x).
203  Res = CastInst::CreateIntegerCast(I->getOperand(0), Ty,
204  Opc == Instruction::SExt);
205  break;
206  case Instruction::Select: {
207  Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
208  Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
209  Res = SelectInst::Create(I->getOperand(0), True, False);
210  break;
211  }
212  case Instruction::PHI: {
213  PHINode *OPN = cast<PHINode>(I);
214  PHINode *NPN = PHINode::Create(Ty, OPN->getNumIncomingValues());
215  for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
216  Value *V =
217  EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
218  NPN->addIncoming(V, OPN->getIncomingBlock(i));
219  }
220  Res = NPN;
221  break;
222  }
223  default:
224  // TODO: Can handle more cases here.
225  llvm_unreachable("Unreachable!");
226  }
227 
228  Res->takeName(I);
229  return InsertNewInstWith(Res, *I);
230 }
231 
232 Instruction::CastOps InstCombiner::isEliminableCastPair(const CastInst *CI1,
233  const CastInst *CI2) {
234  Type *SrcTy = CI1->getSrcTy();
235  Type *MidTy = CI1->getDestTy();
236  Type *DstTy = CI2->getDestTy();
237 
238  Instruction::CastOps firstOp = CI1->getOpcode();
239  Instruction::CastOps secondOp = CI2->getOpcode();
240  Type *SrcIntPtrTy =
241  SrcTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(SrcTy) : nullptr;
242  Type *MidIntPtrTy =
243  MidTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(MidTy) : nullptr;
244  Type *DstIntPtrTy =
245  DstTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(DstTy) : nullptr;
246  unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
247  DstTy, SrcIntPtrTy, MidIntPtrTy,
248  DstIntPtrTy);
249 
250  // We don't want to form an inttoptr or ptrtoint that converts to an integer
251  // type that differs from the pointer size.
252  if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
253  (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
254  Res = 0;
255 
256  return Instruction::CastOps(Res);
257 }
258 
259 /// Implement the transforms common to all CastInst visitors.
261  Value *Src = CI.getOperand(0);
262 
263  // Try to eliminate a cast of a cast.
264  if (auto *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
265  if (Instruction::CastOps NewOpc = isEliminableCastPair(CSrc, &CI)) {
266  // The first cast (CSrc) is eliminable so we need to fix up or replace
267  // the second cast (CI). CSrc will then have a good chance of being dead.
268  auto *Ty = CI.getType();
269  auto *Res = CastInst::Create(NewOpc, CSrc->getOperand(0), Ty);
270  // Point debug users of the dying cast to the new one.
271  if (CSrc->hasOneUse())
272  replaceAllDbgUsesWith(*CSrc, *Res, CI, DT);
273  return Res;
274  }
275  }
276 
277  if (auto *Sel = dyn_cast<SelectInst>(Src)) {
278  // We are casting a select. Try to fold the cast into the select, but only
279  // if the select does not have a compare instruction with matching operand
280  // types. Creating a select with operands that are different sizes than its
281  // condition may inhibit other folds and lead to worse codegen.
282  auto *Cmp = dyn_cast<CmpInst>(Sel->getCondition());
283  if (!Cmp || Cmp->getOperand(0)->getType() != Sel->getType())
284  if (Instruction *NV = FoldOpIntoSelect(CI, Sel)) {
285  replaceAllDbgUsesWith(*Sel, *NV, CI, DT);
286  return NV;
287  }
288  }
289 
290  // If we are casting a PHI, then fold the cast into the PHI.
291  if (auto *PN = dyn_cast<PHINode>(Src)) {
292  // Don't do this if it would create a PHI node with an illegal type from a
293  // legal type.
294  if (!Src->getType()->isIntegerTy() || !CI.getType()->isIntegerTy() ||
295  shouldChangeType(CI.getType(), Src->getType()))
296  if (Instruction *NV = foldOpIntoPhi(CI, PN))
297  return NV;
298  }
299 
300  return nullptr;
301 }
302 
303 /// Constants and extensions/truncates from the destination type are always
304 /// free to be evaluated in that type. This is a helper for canEvaluate*.
305 static bool canAlwaysEvaluateInType(Value *V, Type *Ty) {
306  if (isa<Constant>(V))
307  return true;
308  Value *X;
309  if ((match(V, m_ZExtOrSExt(m_Value(X))) || match(V, m_Trunc(m_Value(X)))) &&
310  X->getType() == Ty)
311  return true;
312 
313  return false;
314 }
315 
316 /// Filter out values that we can not evaluate in the destination type for free.
317 /// This is a helper for canEvaluate*.
318 static bool canNotEvaluateInType(Value *V, Type *Ty) {
319  assert(!isa<Constant>(V) && "Constant should already be handled.");
320  if (!isa<Instruction>(V))
321  return true;
322  // We don't extend or shrink something that has multiple uses -- doing so
323  // would require duplicating the instruction which isn't profitable.
324  if (!V->hasOneUse())
325  return true;
326 
327  return false;
328 }
329 
330 /// Return true if we can evaluate the specified expression tree as type Ty
331 /// instead of its larger type, and arrive with the same value.
332 /// This is used by code that tries to eliminate truncates.
333 ///
334 /// Ty will always be a type smaller than V. We should return true if trunc(V)
335 /// can be computed by computing V in the smaller type. If V is an instruction,
336 /// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
337 /// makes sense if x and y can be efficiently truncated.
338 ///
339 /// This function works on both vectors and scalars.
340 ///
341 static bool canEvaluateTruncated(Value *V, Type *Ty, InstCombiner &IC,
342  Instruction *CxtI) {
343  if (canAlwaysEvaluateInType(V, Ty))
344  return true;
345  if (canNotEvaluateInType(V, Ty))
346  return false;
347 
348  auto *I = cast<Instruction>(V);
349  Type *OrigTy = V->getType();
350  switch (I->getOpcode()) {
351  case Instruction::Add:
352  case Instruction::Sub:
353  case Instruction::Mul:
354  case Instruction::And:
355  case Instruction::Or:
356  case Instruction::Xor:
357  // These operators can all arbitrarily be extended or truncated.
358  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
359  canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
360 
361  case Instruction::UDiv:
362  case Instruction::URem: {
363  // UDiv and URem can be truncated if all the truncated bits are zero.
364  uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
365  uint32_t BitWidth = Ty->getScalarSizeInBits();
366  assert(BitWidth < OrigBitWidth && "Unexpected bitwidths!");
367  APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
368  if (IC.MaskedValueIsZero(I->getOperand(0), Mask, 0, CxtI) &&
369  IC.MaskedValueIsZero(I->getOperand(1), Mask, 0, CxtI)) {
370  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
371  canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
372  }
373  break;
374  }
375  case Instruction::Shl: {
376  // If we are truncating the result of this SHL, and if it's a shift of a
377  // constant amount, we can always perform a SHL in a smaller type.
378  const APInt *Amt;
379  if (match(I->getOperand(1), m_APInt(Amt))) {
380  uint32_t BitWidth = Ty->getScalarSizeInBits();
381  if (Amt->getLimitedValue(BitWidth) < BitWidth)
382  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
383  }
384  break;
385  }
386  case Instruction::LShr: {
387  // If this is a truncate of a logical shr, we can truncate it to a smaller
388  // lshr iff we know that the bits we would otherwise be shifting in are
389  // already zeros.
390  const APInt *Amt;
391  if (match(I->getOperand(1), m_APInt(Amt))) {
392  uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
393  uint32_t BitWidth = Ty->getScalarSizeInBits();
394  if (Amt->getLimitedValue(BitWidth) < BitWidth &&
395  IC.MaskedValueIsZero(I->getOperand(0),
396  APInt::getBitsSetFrom(OrigBitWidth, BitWidth), 0, CxtI)) {
397  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
398  }
399  }
400  break;
401  }
402  case Instruction::AShr: {
403  // If this is a truncate of an arithmetic shr, we can truncate it to a
404  // smaller ashr iff we know that all the bits from the sign bit of the
405  // original type and the sign bit of the truncate type are similar.
406  // TODO: It is enough to check that the bits we would be shifting in are
407  // similar to sign bit of the truncate type.
408  const APInt *Amt;
409  if (match(I->getOperand(1), m_APInt(Amt))) {
410  uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
411  uint32_t BitWidth = Ty->getScalarSizeInBits();
412  if (Amt->getLimitedValue(BitWidth) < BitWidth &&
413  OrigBitWidth - BitWidth <
414  IC.ComputeNumSignBits(I->getOperand(0), 0, CxtI))
415  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
416  }
417  break;
418  }
419  case Instruction::Trunc:
420  // trunc(trunc(x)) -> trunc(x)
421  return true;
422  case Instruction::ZExt:
423  case Instruction::SExt:
424  // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
425  // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
426  return true;
427  case Instruction::Select: {
428  SelectInst *SI = cast<SelectInst>(I);
429  return canEvaluateTruncated(SI->getTrueValue(), Ty, IC, CxtI) &&
430  canEvaluateTruncated(SI->getFalseValue(), Ty, IC, CxtI);
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 (!canEvaluateTruncated(IncValue, Ty, IC, CxtI))
439  return false;
440  return true;
441  }
442  default:
443  // TODO: Can handle more cases here.
444  break;
445  }
446 
447  return false;
448 }
449 
450 /// Given a vector that is bitcast to an integer, optionally logically
451 /// right-shifted, and truncated, convert it to an extractelement.
452 /// Example (big endian):
453 /// trunc (lshr (bitcast <4 x i32> %X to i128), 32) to i32
454 /// --->
455 /// extractelement <4 x i32> %X, 1
457  Value *TruncOp = Trunc.getOperand(0);
458  Type *DestType = Trunc.getType();
459  if (!TruncOp->hasOneUse() || !isa<IntegerType>(DestType))
460  return nullptr;
461 
462  Value *VecInput = nullptr;
463  ConstantInt *ShiftVal = nullptr;
464  if (!match(TruncOp, m_CombineOr(m_BitCast(m_Value(VecInput)),
465  m_LShr(m_BitCast(m_Value(VecInput)),
466  m_ConstantInt(ShiftVal)))) ||
467  !isa<VectorType>(VecInput->getType()))
468  return nullptr;
469 
470  VectorType *VecType = cast<VectorType>(VecInput->getType());
471  unsigned VecWidth = VecType->getPrimitiveSizeInBits();
472  unsigned DestWidth = DestType->getPrimitiveSizeInBits();
473  unsigned ShiftAmount = ShiftVal ? ShiftVal->getZExtValue() : 0;
474 
475  if ((VecWidth % DestWidth != 0) || (ShiftAmount % DestWidth != 0))
476  return nullptr;
477 
478  // If the element type of the vector doesn't match the result type,
479  // bitcast it to a vector type that we can extract from.
480  unsigned NumVecElts = VecWidth / DestWidth;
481  if (VecType->getElementType() != DestType) {
482  VecType = VectorType::get(DestType, NumVecElts);
483  VecInput = IC.Builder.CreateBitCast(VecInput, VecType, "bc");
484  }
485 
486  unsigned Elt = ShiftAmount / DestWidth;
487  if (IC.getDataLayout().isBigEndian())
488  Elt = NumVecElts - 1 - Elt;
489 
490  return ExtractElementInst::Create(VecInput, IC.Builder.getInt32(Elt));
491 }
492 
493 /// Rotate left/right may occur in a wider type than necessary because of type
494 /// promotion rules. Try to narrow the inputs and convert to funnel shift.
495 Instruction *InstCombiner::narrowRotate(TruncInst &Trunc) {
496  assert((isa<VectorType>(Trunc.getSrcTy()) ||
497  shouldChangeType(Trunc.getSrcTy(), Trunc.getType())) &&
498  "Don't narrow to an illegal scalar type");
499 
500  // Bail out on strange types. It is possible to handle some of these patterns
501  // even with non-power-of-2 sizes, but it is not a likely scenario.
502  Type *DestTy = Trunc.getType();
503  unsigned NarrowWidth = DestTy->getScalarSizeInBits();
504  if (!isPowerOf2_32(NarrowWidth))
505  return nullptr;
506 
507  // First, find an or'd pair of opposite shifts with the same shifted operand:
508  // trunc (or (lshr ShVal, ShAmt0), (shl ShVal, ShAmt1))
509  Value *Or0, *Or1;
510  if (!match(Trunc.getOperand(0), m_OneUse(m_Or(m_Value(Or0), m_Value(Or1)))))
511  return nullptr;
512 
513  Value *ShVal, *ShAmt0, *ShAmt1;
514  if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal), m_Value(ShAmt0)))) ||
515  !match(Or1, m_OneUse(m_LogicalShift(m_Specific(ShVal), m_Value(ShAmt1)))))
516  return nullptr;
517 
518  auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode();
519  auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode();
520  if (ShiftOpcode0 == ShiftOpcode1)
521  return nullptr;
522 
523  // Match the shift amount operands for a rotate pattern. This always matches
524  // a subtraction on the R operand.
525  auto matchShiftAmount = [](Value *L, Value *R, unsigned Width) -> Value * {
526  // The shift amounts may add up to the narrow bit width:
527  // (shl ShVal, L) | (lshr ShVal, Width - L)
529  return L;
530 
531  // The shift amount may be masked with negation:
532  // (shl ShVal, (X & (Width - 1))) | (lshr ShVal, ((-X) & (Width - 1)))
533  Value *X;
534  unsigned Mask = Width - 1;
535  if (match(L, m_And(m_Value(X), m_SpecificInt(Mask))) &&
536  match(R, m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask))))
537  return X;
538 
539  // Same as above, but the shift amount may be extended after masking:
540  if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) &&
541  match(R, m_ZExt(m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask)))))
542  return X;
543 
544  return nullptr;
545  };
546 
547  Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, NarrowWidth);
548  bool SubIsOnLHS = false;
549  if (!ShAmt) {
550  ShAmt = matchShiftAmount(ShAmt1, ShAmt0, NarrowWidth);
551  SubIsOnLHS = true;
552  }
553  if (!ShAmt)
554  return nullptr;
555 
556  // The shifted value must have high zeros in the wide type. Typically, this
557  // will be a zext, but it could also be the result of an 'and' or 'shift'.
558  unsigned WideWidth = Trunc.getSrcTy()->getScalarSizeInBits();
559  APInt HiBitMask = APInt::getHighBitsSet(WideWidth, WideWidth - NarrowWidth);
560  if (!MaskedValueIsZero(ShVal, HiBitMask, 0, &Trunc))
561  return nullptr;
562 
563  // We have an unnecessarily wide rotate!
564  // trunc (or (lshr ShVal, ShAmt), (shl ShVal, BitWidth - ShAmt))
565  // Narrow the inputs and convert to funnel shift intrinsic:
566  // llvm.fshl.i8(trunc(ShVal), trunc(ShVal), trunc(ShAmt))
567  Value *NarrowShAmt = Builder.CreateTrunc(ShAmt, DestTy);
568  Value *X = Builder.CreateTrunc(ShVal, DestTy);
569  bool IsFshl = (!SubIsOnLHS && ShiftOpcode0 == BinaryOperator::Shl) ||
570  (SubIsOnLHS && ShiftOpcode1 == BinaryOperator::Shl);
571  Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
572  Function *F = Intrinsic::getDeclaration(Trunc.getModule(), IID, DestTy);
573  return IntrinsicInst::Create(F, { X, X, NarrowShAmt });
574 }
575 
576 /// Try to narrow the width of math or bitwise logic instructions by pulling a
577 /// truncate ahead of binary operators.
578 /// TODO: Transforms for truncated shifts should be moved into here.
579 Instruction *InstCombiner::narrowBinOp(TruncInst &Trunc) {
580  Type *SrcTy = Trunc.getSrcTy();
581  Type *DestTy = Trunc.getType();
582  if (!isa<VectorType>(SrcTy) && !shouldChangeType(SrcTy, DestTy))
583  return nullptr;
584 
585  BinaryOperator *BinOp;
586  if (!match(Trunc.getOperand(0), m_OneUse(m_BinOp(BinOp))))
587  return nullptr;
588 
589  Value *BinOp0 = BinOp->getOperand(0);
590  Value *BinOp1 = BinOp->getOperand(1);
591  switch (BinOp->getOpcode()) {
592  case Instruction::And:
593  case Instruction::Or:
594  case Instruction::Xor:
595  case Instruction::Add:
596  case Instruction::Sub:
597  case Instruction::Mul: {
598  Constant *C;
599  if (match(BinOp0, m_Constant(C))) {
600  // trunc (binop C, X) --> binop (trunc C', X)
601  Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
602  Value *TruncX = Builder.CreateTrunc(BinOp1, DestTy);
603  return BinaryOperator::Create(BinOp->getOpcode(), NarrowC, TruncX);
604  }
605  if (match(BinOp1, m_Constant(C))) {
606  // trunc (binop X, C) --> binop (trunc X, C')
607  Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
608  Value *TruncX = Builder.CreateTrunc(BinOp0, DestTy);
609  return BinaryOperator::Create(BinOp->getOpcode(), TruncX, NarrowC);
610  }
611  Value *X;
612  if (match(BinOp0, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) {
613  // trunc (binop (ext X), Y) --> binop X, (trunc Y)
614  Value *NarrowOp1 = Builder.CreateTrunc(BinOp1, DestTy);
615  return BinaryOperator::Create(BinOp->getOpcode(), X, NarrowOp1);
616  }
617  if (match(BinOp1, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) {
618  // trunc (binop Y, (ext X)) --> binop (trunc Y), X
619  Value *NarrowOp0 = Builder.CreateTrunc(BinOp0, DestTy);
620  return BinaryOperator::Create(BinOp->getOpcode(), NarrowOp0, X);
621  }
622  break;
623  }
624 
625  default: break;
626  }
627 
628  if (Instruction *NarrowOr = narrowRotate(Trunc))
629  return NarrowOr;
630 
631  return nullptr;
632 }
633 
634 /// Try to narrow the width of a splat shuffle. This could be generalized to any
635 /// shuffle with a constant operand, but we limit the transform to avoid
636 /// creating a shuffle type that targets may not be able to lower effectively.
638  InstCombiner::BuilderTy &Builder) {
639  auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
640  if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) &&
641  Shuf->getMask()->getSplatValue() &&
642  Shuf->getType() == Shuf->getOperand(0)->getType()) {
643  // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
644  Constant *NarrowUndef = UndefValue::get(Trunc.getType());
645  Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
646  return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getMask());
647  }
648 
649  return nullptr;
650 }
651 
652 /// Try to narrow the width of an insert element. This could be generalized for
653 /// any vector constant, but we limit the transform to insertion into undef to
654 /// avoid potential backend problems from unsupported insertion widths. This
655 /// could also be extended to handle the case of inserting a scalar constant
656 /// into a vector variable.
658  InstCombiner::BuilderTy &Builder) {
659  Instruction::CastOps Opcode = Trunc.getOpcode();
660  assert((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) &&
661  "Unexpected instruction for shrinking");
662 
663  auto *InsElt = dyn_cast<InsertElementInst>(Trunc.getOperand(0));
664  if (!InsElt || !InsElt->hasOneUse())
665  return nullptr;
666 
667  Type *DestTy = Trunc.getType();
668  Type *DestScalarTy = DestTy->getScalarType();
669  Value *VecOp = InsElt->getOperand(0);
670  Value *ScalarOp = InsElt->getOperand(1);
671  Value *Index = InsElt->getOperand(2);
672 
673  if (isa<UndefValue>(VecOp)) {
674  // trunc (inselt undef, X, Index) --> inselt undef, (trunc X), Index
675  // fptrunc (inselt undef, X, Index) --> inselt undef, (fptrunc X), Index
676  UndefValue *NarrowUndef = UndefValue::get(DestTy);
677  Value *NarrowOp = Builder.CreateCast(Opcode, ScalarOp, DestScalarTy);
678  return InsertElementInst::Create(NarrowUndef, NarrowOp, Index);
679  }
680 
681  return nullptr;
682 }
683 
685  if (Instruction *Result = commonCastTransforms(CI))
686  return Result;
687 
688  Value *Src = CI.getOperand(0);
689  Type *DestTy = CI.getType(), *SrcTy = Src->getType();
690 
691  // Attempt to truncate the entire input expression tree to the destination
692  // type. Only do this if the dest type is a simple type, don't convert the
693  // expression tree to something weird like i93 unless the source is also
694  // strange.
695  if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) &&
696  canEvaluateTruncated(Src, DestTy, *this, &CI)) {
697 
698  // If this cast is a truncate, evaluting in a different type always
699  // eliminates the cast, so it is always a win.
700  LLVM_DEBUG(
701  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
702  " to avoid cast: "
703  << CI << '\n');
704  Value *Res = EvaluateInDifferentType(Src, DestTy, false);
705  assert(Res->getType() == DestTy);
706  return replaceInstUsesWith(CI, Res);
707  }
708 
709  // Test if the trunc is the user of a select which is part of a
710  // minimum or maximum operation. If so, don't do any more simplification.
711  // Even simplifying demanded bits can break the canonical form of a
712  // min/max.
713  Value *LHS, *RHS;
714  if (SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0)))
715  if (matchSelectPattern(SI, LHS, RHS).Flavor != SPF_UNKNOWN)
716  return nullptr;
717 
718  // See if we can simplify any instructions used by the input whose sole
719  // purpose is to compute bits we don't care about.
720  if (SimplifyDemandedInstructionBits(CI))
721  return &CI;
722 
723  if (DestTy->getScalarSizeInBits() == 1) {
724  Value *Zero = Constant::getNullValue(Src->getType());
725  if (DestTy->isIntegerTy()) {
726  // Canonicalize trunc x to i1 -> icmp ne (and x, 1), 0 (scalar only).
727  // TODO: We canonicalize to more instructions here because we are probably
728  // lacking equivalent analysis for trunc relative to icmp. There may also
729  // be codegen concerns. If those trunc limitations were removed, we could
730  // remove this transform.
731  Value *And = Builder.CreateAnd(Src, ConstantInt::get(SrcTy, 1));
732  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
733  }
734 
735  // For vectors, we do not canonicalize all truncs to icmp, so optimize
736  // patterns that would be covered within visitICmpInst.
737  Value *X;
738  const APInt *C;
739  if (match(Src, m_OneUse(m_LShr(m_Value(X), m_APInt(C))))) {
740  // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0
741  APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C);
742  Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC));
743  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
744  }
745  if (match(Src, m_OneUse(m_c_Or(m_LShr(m_Value(X), m_APInt(C)),
746  m_Deferred(X))))) {
747  // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0
748  APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C) | 1;
749  Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC));
750  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
751  }
752  }
753 
754  // FIXME: Maybe combine the next two transforms to handle the no cast case
755  // more efficiently. Support vector types. Cleanup code by using m_OneUse.
756 
757  // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
758  Value *A = nullptr; ConstantInt *Cst = nullptr;
759  if (Src->hasOneUse() &&
760  match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
761  // We have three types to worry about here, the type of A, the source of
762  // the truncate (MidSize), and the destination of the truncate. We know that
763  // ASize < MidSize and MidSize > ResultSize, but don't know the relation
764  // between ASize and ResultSize.
765  unsigned ASize = A->getType()->getPrimitiveSizeInBits();
766 
767  // If the shift amount is larger than the size of A, then the result is
768  // known to be zero because all the input bits got shifted out.
769  if (Cst->getZExtValue() >= ASize)
770  return replaceInstUsesWith(CI, Constant::getNullValue(DestTy));
771 
772  // Since we're doing an lshr and a zero extend, and know that the shift
773  // amount is smaller than ASize, it is always safe to do the shift in A's
774  // type, then zero extend or truncate to the result.
775  Value *Shift = Builder.CreateLShr(A, Cst->getZExtValue());
776  Shift->takeName(Src);
777  return CastInst::CreateIntegerCast(Shift, DestTy, false);
778  }
779 
780  // FIXME: We should canonicalize to zext/trunc and remove this transform.
781  // Transform trunc(lshr (sext A), Cst) to ashr A, Cst to eliminate type
782  // conversion.
783  // It works because bits coming from sign extension have the same value as
784  // the sign bit of the original value; performing ashr instead of lshr
785  // generates bits of the same value as the sign bit.
786  if (Src->hasOneUse() &&
787  match(Src, m_LShr(m_SExt(m_Value(A)), m_ConstantInt(Cst)))) {
788  Value *SExt = cast<Instruction>(Src)->getOperand(0);
789  const unsigned SExtSize = SExt->getType()->getPrimitiveSizeInBits();
790  const unsigned ASize = A->getType()->getPrimitiveSizeInBits();
791  const unsigned CISize = CI.getType()->getPrimitiveSizeInBits();
792  const unsigned MaxAmt = SExtSize - std::max(CISize, ASize);
793  unsigned ShiftAmt = Cst->getZExtValue();
794 
795  // This optimization can be only performed when zero bits generated by
796  // the original lshr aren't pulled into the value after truncation, so we
797  // can only shift by values no larger than the number of extension bits.
798  // FIXME: Instead of bailing when the shift is too large, use and to clear
799  // the extra bits.
800  if (ShiftAmt <= MaxAmt) {
801  if (CISize == ASize)
802  return BinaryOperator::CreateAShr(A, ConstantInt::get(CI.getType(),
803  std::min(ShiftAmt, ASize - 1)));
804  if (SExt->hasOneUse()) {
805  Value *Shift = Builder.CreateAShr(A, std::min(ShiftAmt, ASize - 1));
806  Shift->takeName(Src);
807  return CastInst::CreateIntegerCast(Shift, CI.getType(), true);
808  }
809  }
810  }
811 
812  if (Instruction *I = narrowBinOp(CI))
813  return I;
814 
815  if (Instruction *I = shrinkSplatShuffle(CI, Builder))
816  return I;
817 
818  if (Instruction *I = shrinkInsertElt(CI, Builder))
819  return I;
820 
821  if (Src->hasOneUse() && isa<IntegerType>(SrcTy) &&
822  shouldChangeType(SrcTy, DestTy)) {
823  // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
824  // dest type is native and cst < dest size.
825  if (match(Src, m_Shl(m_Value(A), m_ConstantInt(Cst))) &&
826  !match(A, m_Shr(m_Value(), m_Constant()))) {
827  // Skip shifts of shift by constants. It undoes a combine in
828  // FoldShiftByConstant and is the extend in reg pattern.
829  const unsigned DestSize = DestTy->getScalarSizeInBits();
830  if (Cst->getValue().ult(DestSize)) {
831  Value *NewTrunc = Builder.CreateTrunc(A, DestTy, A->getName() + ".tr");
832 
833  return BinaryOperator::Create(
834  Instruction::Shl, NewTrunc,
835  ConstantInt::get(DestTy, Cst->getValue().trunc(DestSize)));
836  }
837  }
838  }
839 
840  if (Instruction *I = foldVecTruncToExtElt(CI, *this))
841  return I;
842 
843  return nullptr;
844 }
845 
846 Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, ZExtInst &CI,
847  bool DoTransform) {
848  // If we are just checking for a icmp eq of a single bit and zext'ing it
849  // to an integer, then shift the bit to the appropriate place and then
850  // cast to integer to avoid the comparison.
851  const APInt *Op1CV;
852  if (match(ICI->getOperand(1), m_APInt(Op1CV))) {
853 
854  // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
855  // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
856  if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isNullValue()) ||
857  (ICI->getPredicate() == ICmpInst::ICMP_SGT && Op1CV->isAllOnesValue())) {
858  if (!DoTransform) return ICI;
859 
860  Value *In = ICI->getOperand(0);
861  Value *Sh = ConstantInt::get(In->getType(),
862  In->getType()->getScalarSizeInBits() - 1);
863  In = Builder.CreateLShr(In, Sh, In->getName() + ".lobit");
864  if (In->getType() != CI.getType())
865  In = Builder.CreateIntCast(In, CI.getType(), false /*ZExt*/);
866 
867  if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
868  Constant *One = ConstantInt::get(In->getType(), 1);
869  In = Builder.CreateXor(In, One, In->getName() + ".not");
870  }
871 
872  return replaceInstUsesWith(CI, In);
873  }
874 
875  // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
876  // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
877  // zext (X == 1) to i32 --> X iff X has only the low bit set.
878  // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
879  // zext (X != 0) to i32 --> X iff X has only the low bit set.
880  // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
881  // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
882  // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
883  if ((Op1CV->isNullValue() || Op1CV->isPowerOf2()) &&
884  // This only works for EQ and NE
885  ICI->isEquality()) {
886  // If Op1C some other power of two, convert:
887  KnownBits Known = computeKnownBits(ICI->getOperand(0), 0, &CI);
888 
889  APInt KnownZeroMask(~Known.Zero);
890  if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
891  if (!DoTransform) return ICI;
892 
893  bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
894  if (!Op1CV->isNullValue() && (*Op1CV != KnownZeroMask)) {
895  // (X&4) == 2 --> false
896  // (X&4) != 2 --> true
897  Constant *Res = ConstantInt::get(CI.getType(), isNE);
898  return replaceInstUsesWith(CI, Res);
899  }
900 
901  uint32_t ShAmt = KnownZeroMask.logBase2();
902  Value *In = ICI->getOperand(0);
903  if (ShAmt) {
904  // Perform a logical shr by shiftamt.
905  // Insert the shift to put the result in the low bit.
906  In = Builder.CreateLShr(In, ConstantInt::get(In->getType(), ShAmt),
907  In->getName() + ".lobit");
908  }
909 
910  if (!Op1CV->isNullValue() == isNE) { // Toggle the low bit.
911  Constant *One = ConstantInt::get(In->getType(), 1);
912  In = Builder.CreateXor(In, One);
913  }
914 
915  if (CI.getType() == In->getType())
916  return replaceInstUsesWith(CI, In);
917 
918  Value *IntCast = Builder.CreateIntCast(In, CI.getType(), false);
919  return replaceInstUsesWith(CI, IntCast);
920  }
921  }
922  }
923 
924  // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
925  // It is also profitable to transform icmp eq into not(xor(A, B)) because that
926  // may lead to additional simplifications.
927  if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
928  if (IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
929  Value *LHS = ICI->getOperand(0);
930  Value *RHS = ICI->getOperand(1);
931 
932  KnownBits KnownLHS = computeKnownBits(LHS, 0, &CI);
933  KnownBits KnownRHS = computeKnownBits(RHS, 0, &CI);
934 
935  if (KnownLHS.Zero == KnownRHS.Zero && KnownLHS.One == KnownRHS.One) {
936  APInt KnownBits = KnownLHS.Zero | KnownLHS.One;
937  APInt UnknownBit = ~KnownBits;
938  if (UnknownBit.countPopulation() == 1) {
939  if (!DoTransform) return ICI;
940 
941  Value *Result = Builder.CreateXor(LHS, RHS);
942 
943  // Mask off any bits that are set and won't be shifted away.
944  if (KnownLHS.One.uge(UnknownBit))
945  Result = Builder.CreateAnd(Result,
946  ConstantInt::get(ITy, UnknownBit));
947 
948  // Shift the bit we're testing down to the lsb.
949  Result = Builder.CreateLShr(
950  Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
951 
952  if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
953  Result = Builder.CreateXor(Result, ConstantInt::get(ITy, 1));
954  Result->takeName(ICI);
955  return replaceInstUsesWith(CI, Result);
956  }
957  }
958  }
959  }
960 
961  return nullptr;
962 }
963 
964 /// Determine if the specified value can be computed in the specified wider type
965 /// and produce the same low bits. If not, return false.
966 ///
967 /// If this function returns true, it can also return a non-zero number of bits
968 /// (in BitsToClear) which indicates that the value it computes is correct for
969 /// the zero extend, but that the additional BitsToClear bits need to be zero'd
970 /// out. For example, to promote something like:
971 ///
972 /// %B = trunc i64 %A to i32
973 /// %C = lshr i32 %B, 8
974 /// %E = zext i32 %C to i64
975 ///
976 /// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
977 /// set to 8 to indicate that the promoted value needs to have bits 24-31
978 /// cleared in addition to bits 32-63. Since an 'and' will be generated to
979 /// clear the top bits anyway, doing this has no extra cost.
980 ///
981 /// This function works on both vectors and scalars.
982 static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear,
983  InstCombiner &IC, Instruction *CxtI) {
984  BitsToClear = 0;
985  if (canAlwaysEvaluateInType(V, Ty))
986  return true;
987  if (canNotEvaluateInType(V, Ty))
988  return false;
989 
990  auto *I = cast<Instruction>(V);
991  unsigned Tmp;
992  switch (I->getOpcode()) {
993  case Instruction::ZExt: // zext(zext(x)) -> zext(x).
994  case Instruction::SExt: // zext(sext(x)) -> sext(x).
995  case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
996  return true;
997  case Instruction::And:
998  case Instruction::Or:
999  case Instruction::Xor:
1000  case Instruction::Add:
1001  case Instruction::Sub:
1002  case Instruction::Mul:
1003  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI) ||
1004  !canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI))
1005  return false;
1006  // These can all be promoted if neither operand has 'bits to clear'.
1007  if (BitsToClear == 0 && Tmp == 0)
1008  return true;
1009 
1010  // If the operation is an AND/OR/XOR and the bits to clear are zero in the
1011  // other side, BitsToClear is ok.
1012  if (Tmp == 0 && I->isBitwiseLogicOp()) {
1013  // We use MaskedValueIsZero here for generality, but the case we care
1014  // about the most is constant RHS.
1015  unsigned VSize = V->getType()->getScalarSizeInBits();
1016  if (IC.MaskedValueIsZero(I->getOperand(1),
1017  APInt::getHighBitsSet(VSize, BitsToClear),
1018  0, CxtI)) {
1019  // If this is an And instruction and all of the BitsToClear are
1020  // known to be zero we can reset BitsToClear.
1021  if (I->getOpcode() == Instruction::And)
1022  BitsToClear = 0;
1023  return true;
1024  }
1025  }
1026 
1027  // Otherwise, we don't know how to analyze this BitsToClear case yet.
1028  return false;
1029 
1030  case Instruction::Shl: {
1031  // We can promote shl(x, cst) if we can promote x. Since shl overwrites the
1032  // upper bits we can reduce BitsToClear by the shift amount.
1033  const APInt *Amt;
1034  if (match(I->getOperand(1), m_APInt(Amt))) {
1035  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
1036  return false;
1037  uint64_t ShiftAmt = Amt->getZExtValue();
1038  BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
1039  return true;
1040  }
1041  return false;
1042  }
1043  case Instruction::LShr: {
1044  // We can promote lshr(x, cst) if we can promote x. This requires the
1045  // ultimate 'and' to clear out the high zero bits we're clearing out though.
1046  const APInt *Amt;
1047  if (match(I->getOperand(1), m_APInt(Amt))) {
1048  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
1049  return false;
1050  BitsToClear += Amt->getZExtValue();
1051  if (BitsToClear > V->getType()->getScalarSizeInBits())
1052  BitsToClear = V->getType()->getScalarSizeInBits();
1053  return true;
1054  }
1055  // Cannot promote variable LSHR.
1056  return false;
1057  }
1058  case Instruction::Select:
1059  if (!canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI) ||
1060  !canEvaluateZExtd(I->getOperand(2), Ty, BitsToClear, IC, CxtI) ||
1061  // TODO: If important, we could handle the case when the BitsToClear are
1062  // known zero in the disagreeing side.
1063  Tmp != BitsToClear)
1064  return false;
1065  return true;
1066 
1067  case Instruction::PHI: {
1068  // We can change a phi if we can change all operands. Note that we never
1069  // get into trouble with cyclic PHIs here because we only consider
1070  // instructions with a single use.
1071  PHINode *PN = cast<PHINode>(I);
1072  if (!canEvaluateZExtd(PN->getIncomingValue(0), Ty, BitsToClear, IC, CxtI))
1073  return false;
1074  for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
1075  if (!canEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp, IC, CxtI) ||
1076  // TODO: If important, we could handle the case when the BitsToClear
1077  // are known zero in the disagreeing input.
1078  Tmp != BitsToClear)
1079  return false;
1080  return true;
1081  }
1082  default:
1083  // TODO: Can handle more cases here.
1084  return false;
1085  }
1086 }
1087 
1089  // If this zero extend is only used by a truncate, let the truncate be
1090  // eliminated before we try to optimize this zext.
1091  if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
1092  return nullptr;
1093 
1094  // If one of the common conversion will work, do it.
1095  if (Instruction *Result = commonCastTransforms(CI))
1096  return Result;
1097 
1098  Value *Src = CI.getOperand(0);
1099  Type *SrcTy = Src->getType(), *DestTy = CI.getType();
1100 
1101  // Try to extend the entire expression tree to the wide destination type.
1102  unsigned BitsToClear;
1103  if (shouldChangeType(SrcTy, DestTy) &&
1104  canEvaluateZExtd(Src, DestTy, BitsToClear, *this, &CI)) {
1105  assert(BitsToClear <= SrcTy->getScalarSizeInBits() &&
1106  "Can't clear more bits than in SrcTy");
1107 
1108  // Okay, we can transform this! Insert the new expression now.
1109  LLVM_DEBUG(
1110  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1111  " to avoid zero extend: "
1112  << CI << '\n');
1113  Value *Res = EvaluateInDifferentType(Src, DestTy, false);
1114  assert(Res->getType() == DestTy);
1115 
1116  // Preserve debug values referring to Src if the zext is its last use.
1117  if (auto *SrcOp = dyn_cast<Instruction>(Src))
1118  if (SrcOp->hasOneUse())
1119  replaceAllDbgUsesWith(*SrcOp, *Res, CI, DT);
1120 
1121  uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear;
1122  uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1123 
1124  // If the high bits are already filled with zeros, just replace this
1125  // cast with the result.
1126  if (MaskedValueIsZero(Res,
1127  APInt::getHighBitsSet(DestBitSize,
1128  DestBitSize-SrcBitsKept),
1129  0, &CI))
1130  return replaceInstUsesWith(CI, Res);
1131 
1132  // We need to emit an AND to clear the high bits.
1133  Constant *C = ConstantInt::get(Res->getType(),
1134  APInt::getLowBitsSet(DestBitSize, SrcBitsKept));
1135  return BinaryOperator::CreateAnd(Res, C);
1136  }
1137 
1138  // If this is a TRUNC followed by a ZEXT then we are dealing with integral
1139  // types and if the sizes are just right we can convert this into a logical
1140  // 'and' which will be much cheaper than the pair of casts.
1141  if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
1142  // TODO: Subsume this into EvaluateInDifferentType.
1143 
1144  // Get the sizes of the types involved. We know that the intermediate type
1145  // will be smaller than A or C, but don't know the relation between A and C.
1146  Value *A = CSrc->getOperand(0);
1147  unsigned SrcSize = A->getType()->getScalarSizeInBits();
1148  unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
1149  unsigned DstSize = CI.getType()->getScalarSizeInBits();
1150  // If we're actually extending zero bits, then if
1151  // SrcSize < DstSize: zext(a & mask)
1152  // SrcSize == DstSize: a & mask
1153  // SrcSize > DstSize: trunc(a) & mask
1154  if (SrcSize < DstSize) {
1155  APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
1156  Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
1157  Value *And = Builder.CreateAnd(A, AndConst, CSrc->getName() + ".mask");
1158  return new ZExtInst(And, CI.getType());
1159  }
1160 
1161  if (SrcSize == DstSize) {
1162  APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
1163  return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
1164  AndValue));
1165  }
1166  if (SrcSize > DstSize) {
1167  Value *Trunc = Builder.CreateTrunc(A, CI.getType());
1168  APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
1169  return BinaryOperator::CreateAnd(Trunc,
1170  ConstantInt::get(Trunc->getType(),
1171  AndValue));
1172  }
1173  }
1174 
1175  if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1176  return transformZExtICmp(ICI, CI);
1177 
1178  BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
1179  if (SrcI && SrcI->getOpcode() == Instruction::Or) {
1180  // zext (or icmp, icmp) -> or (zext icmp), (zext icmp) if at least one
1181  // of the (zext icmp) can be eliminated. If so, immediately perform the
1182  // according elimination.
1183  ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
1184  ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
1185  if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
1186  (transformZExtICmp(LHS, CI, false) ||
1187  transformZExtICmp(RHS, CI, false))) {
1188  // zext (or icmp, icmp) -> or (zext icmp), (zext icmp)
1189  Value *LCast = Builder.CreateZExt(LHS, CI.getType(), LHS->getName());
1190  Value *RCast = Builder.CreateZExt(RHS, CI.getType(), RHS->getName());
1191  BinaryOperator *Or = BinaryOperator::Create(Instruction::Or, LCast, RCast);
1192 
1193  // Perform the elimination.
1194  if (auto *LZExt = dyn_cast<ZExtInst>(LCast))
1195  transformZExtICmp(LHS, *LZExt);
1196  if (auto *RZExt = dyn_cast<ZExtInst>(RCast))
1197  transformZExtICmp(RHS, *RZExt);
1198 
1199  return Or;
1200  }
1201  }
1202 
1203  // zext(trunc(X) & C) -> (X & zext(C)).
1204  Constant *C;
1205  Value *X;
1206  if (SrcI &&
1207  match(SrcI, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) &&
1208  X->getType() == CI.getType())
1209  return BinaryOperator::CreateAnd(X, ConstantExpr::getZExt(C, CI.getType()));
1210 
1211  // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
1212  Value *And;
1213  if (SrcI && match(SrcI, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
1214  match(And, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Specific(C)))) &&
1215  X->getType() == CI.getType()) {
1216  Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
1217  return BinaryOperator::CreateXor(Builder.CreateAnd(X, ZC), ZC);
1218  }
1219 
1220  return nullptr;
1221 }
1222 
1223 /// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
1224 Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) {
1225  Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1);
1226  ICmpInst::Predicate Pred = ICI->getPredicate();
1227 
1228  // Don't bother if Op1 isn't of vector or integer type.
1229  if (!Op1->getType()->isIntOrIntVectorTy())
1230  return nullptr;
1231 
1232  if ((Pred == ICmpInst::ICMP_SLT && match(Op1, m_ZeroInt())) ||
1233  (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))) {
1234  // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if negative
1235  // (x >s -1) ? -1 : 0 -> not (ashr x, 31) -> all ones if positive
1236  Value *Sh = ConstantInt::get(Op0->getType(),
1237  Op0->getType()->getScalarSizeInBits() - 1);
1238  Value *In = Builder.CreateAShr(Op0, Sh, Op0->getName() + ".lobit");
1239  if (In->getType() != CI.getType())
1240  In = Builder.CreateIntCast(In, CI.getType(), true /*SExt*/);
1241 
1242  if (Pred == ICmpInst::ICMP_SGT)
1243  In = Builder.CreateNot(In, In->getName() + ".not");
1244  return replaceInstUsesWith(CI, In);
1245  }
1246 
1247  if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
1248  // If we know that only one bit of the LHS of the icmp can be set and we
1249  // have an equality comparison with zero or a power of 2, we can transform
1250  // the icmp and sext into bitwise/integer operations.
1251  if (ICI->hasOneUse() &&
1252  ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
1253  KnownBits Known = computeKnownBits(Op0, 0, &CI);
1254 
1255  APInt KnownZeroMask(~Known.Zero);
1256  if (KnownZeroMask.isPowerOf2()) {
1257  Value *In = ICI->getOperand(0);
1258 
1259  // If the icmp tests for a known zero bit we can constant fold it.
1260  if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
1261  Value *V = Pred == ICmpInst::ICMP_NE ?
1264  return replaceInstUsesWith(CI, V);
1265  }
1266 
1267  if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
1268  // sext ((x & 2^n) == 0) -> (x >> n) - 1
1269  // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
1270  unsigned ShiftAmt = KnownZeroMask.countTrailingZeros();
1271  // Perform a right shift to place the desired bit in the LSB.
1272  if (ShiftAmt)
1273  In = Builder.CreateLShr(In,
1274  ConstantInt::get(In->getType(), ShiftAmt));
1275 
1276  // At this point "In" is either 1 or 0. Subtract 1 to turn
1277  // {1, 0} -> {0, -1}.
1278  In = Builder.CreateAdd(In,
1280  "sext");
1281  } else {
1282  // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
1283  // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
1284  unsigned ShiftAmt = KnownZeroMask.countLeadingZeros();
1285  // Perform a left shift to place the desired bit in the MSB.
1286  if (ShiftAmt)
1287  In = Builder.CreateShl(In,
1288  ConstantInt::get(In->getType(), ShiftAmt));
1289 
1290  // Distribute the bit over the whole bit width.
1291  In = Builder.CreateAShr(In, ConstantInt::get(In->getType(),
1292  KnownZeroMask.getBitWidth() - 1), "sext");
1293  }
1294 
1295  if (CI.getType() == In->getType())
1296  return replaceInstUsesWith(CI, In);
1297  return CastInst::CreateIntegerCast(In, CI.getType(), true/*SExt*/);
1298  }
1299  }
1300  }
1301 
1302  return nullptr;
1303 }
1304 
1305 /// Return true if we can take the specified value and return it as type Ty
1306 /// without inserting any new casts and without changing the value of the common
1307 /// low bits. This is used by code that tries to promote integer operations to
1308 /// a wider types will allow us to eliminate the extension.
1309 ///
1310 /// This function works on both vectors and scalars.
1311 ///
1312 static bool canEvaluateSExtd(Value *V, Type *Ty) {
1314  "Can't sign extend type to a smaller type");
1315  if (canAlwaysEvaluateInType(V, Ty))
1316  return true;
1317  if (canNotEvaluateInType(V, Ty))
1318  return false;
1319 
1320  auto *I = cast<Instruction>(V);
1321  switch (I->getOpcode()) {
1322  case Instruction::SExt: // sext(sext(x)) -> sext(x)
1323  case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1324  case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1325  return true;
1326  case Instruction::And:
1327  case Instruction::Or:
1328  case Instruction::Xor:
1329  case Instruction::Add:
1330  case Instruction::Sub:
1331  case Instruction::Mul:
1332  // These operators can all arbitrarily be extended if their inputs can.
1333  return canEvaluateSExtd(I->getOperand(0), Ty) &&
1334  canEvaluateSExtd(I->getOperand(1), Ty);
1335 
1336  //case Instruction::Shl: TODO
1337  //case Instruction::LShr: TODO
1338 
1339  case Instruction::Select:
1340  return canEvaluateSExtd(I->getOperand(1), Ty) &&
1341  canEvaluateSExtd(I->getOperand(2), Ty);
1342 
1343  case Instruction::PHI: {
1344  // We can change a phi if we can change all operands. Note that we never
1345  // get into trouble with cyclic PHIs here because we only consider
1346  // instructions with a single use.
1347  PHINode *PN = cast<PHINode>(I);
1348  for (Value *IncValue : PN->incoming_values())
1349  if (!canEvaluateSExtd(IncValue, Ty)) return false;
1350  return true;
1351  }
1352  default:
1353  // TODO: Can handle more cases here.
1354  break;
1355  }
1356 
1357  return false;
1358 }
1359 
1361  // If this sign extend is only used by a truncate, let the truncate be
1362  // eliminated before we try to optimize this sext.
1363  if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
1364  return nullptr;
1365 
1366  if (Instruction *I = commonCastTransforms(CI))
1367  return I;
1368 
1369  Value *Src = CI.getOperand(0);
1370  Type *SrcTy = Src->getType(), *DestTy = CI.getType();
1371 
1372  // If we know that the value being extended is positive, we can use a zext
1373  // instead.
1374  KnownBits Known = computeKnownBits(Src, 0, &CI);
1375  if (Known.isNonNegative())
1376  return CastInst::Create(Instruction::ZExt, Src, DestTy);
1377 
1378  // Try to extend the entire expression tree to the wide destination type.
1379  if (shouldChangeType(SrcTy, DestTy) && canEvaluateSExtd(Src, DestTy)) {
1380  // Okay, we can transform this! Insert the new expression now.
1381  LLVM_DEBUG(
1382  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1383  " to avoid sign extend: "
1384  << CI << '\n');
1385  Value *Res = EvaluateInDifferentType(Src, DestTy, true);
1386  assert(Res->getType() == DestTy);
1387 
1388  uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
1389  uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1390 
1391  // If the high bits are already filled with sign bit, just replace this
1392  // cast with the result.
1393  if (ComputeNumSignBits(Res, 0, &CI) > DestBitSize - SrcBitSize)
1394  return replaceInstUsesWith(CI, Res);
1395 
1396  // We need to emit a shl + ashr to do the sign extend.
1397  Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
1398  return BinaryOperator::CreateAShr(Builder.CreateShl(Res, ShAmt, "sext"),
1399  ShAmt);
1400  }
1401 
1402  // If the input is a trunc from the destination type, then turn sext(trunc(x))
1403  // into shifts.
1404  Value *X;
1405  if (match(Src, m_OneUse(m_Trunc(m_Value(X)))) && X->getType() == DestTy) {
1406  // sext(trunc(X)) --> ashr(shl(X, C), C)
1407  unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
1408  unsigned DestBitSize = DestTy->getScalarSizeInBits();
1409  Constant *ShAmt = ConstantInt::get(DestTy, DestBitSize - SrcBitSize);
1410  return BinaryOperator::CreateAShr(Builder.CreateShl(X, ShAmt), ShAmt);
1411  }
1412 
1413  if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1414  return transformSExtICmp(ICI, CI);
1415 
1416  // If the input is a shl/ashr pair of a same constant, then this is a sign
1417  // extension from a smaller value. If we could trust arbitrary bitwidth
1418  // integers, we could turn this into a truncate to the smaller bit and then
1419  // use a sext for the whole extension. Since we don't, look deeper and check
1420  // for a truncate. If the source and dest are the same type, eliminate the
1421  // trunc and extend and just do shifts. For example, turn:
1422  // %a = trunc i32 %i to i8
1423  // %b = shl i8 %a, 6
1424  // %c = ashr i8 %b, 6
1425  // %d = sext i8 %c to i32
1426  // into:
1427  // %a = shl i32 %i, 30
1428  // %d = ashr i32 %a, 30
1429  Value *A = nullptr;
1430  // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
1431  ConstantInt *BA = nullptr, *CA = nullptr;
1432  if (match(Src, m_AShr(m_Shl(m_Trunc(m_Value(A)), m_ConstantInt(BA)),
1433  m_ConstantInt(CA))) &&
1434  BA == CA && A->getType() == CI.getType()) {
1435  unsigned MidSize = Src->getType()->getScalarSizeInBits();
1436  unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
1437  unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
1438  Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
1439  A = Builder.CreateShl(A, ShAmtV, CI.getName());
1440  return BinaryOperator::CreateAShr(A, ShAmtV);
1441  }
1442 
1443  return nullptr;
1444 }
1445 
1446 
1447 /// Return a Constant* for the specified floating-point constant if it fits
1448 /// in the specified FP type without changing its value.
1449 static bool fitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
1450  bool losesInfo;
1451  APFloat F = CFP->getValueAPF();
1452  (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
1453  return !losesInfo;
1454 }
1455 
1457  if (CFP->getType() == Type::getPPC_FP128Ty(CFP->getContext()))
1458  return nullptr; // No constant folding of this.
1459  // See if the value can be truncated to half and then reextended.
1460  if (fitsInFPType(CFP, APFloat::IEEEhalf()))
1461  return Type::getHalfTy(CFP->getContext());
1462  // See if the value can be truncated to float and then reextended.
1463  if (fitsInFPType(CFP, APFloat::IEEEsingle()))
1464  return Type::getFloatTy(CFP->getContext());
1465  if (CFP->getType()->isDoubleTy())
1466  return nullptr; // Won't shrink.
1467  if (fitsInFPType(CFP, APFloat::IEEEdouble()))
1468  return Type::getDoubleTy(CFP->getContext());
1469  // Don't try to shrink to various long double types.
1470  return nullptr;
1471 }
1472 
1473 // Determine if this is a vector of ConstantFPs and if so, return the minimal
1474 // type we can safely truncate all elements to.
1475 // TODO: Make these support undef elements.
1477  auto *CV = dyn_cast<Constant>(V);
1478  if (!CV || !CV->getType()->isVectorTy())
1479  return nullptr;
1480 
1481  Type *MinType = nullptr;
1482 
1483  unsigned NumElts = CV->getType()->getVectorNumElements();
1484  for (unsigned i = 0; i != NumElts; ++i) {
1485  auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i));
1486  if (!CFP)
1487  return nullptr;
1488 
1489  Type *T = shrinkFPConstant(CFP);
1490  if (!T)
1491  return nullptr;
1492 
1493  // If we haven't found a type yet or this type has a larger mantissa than
1494  // our previous type, this is our new minimal type.
1495  if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth())
1496  MinType = T;
1497  }
1498 
1499  // Make a vector type from the minimal type.
1500  return VectorType::get(MinType, NumElts);
1501 }
1502 
1503 /// Find the minimum FP type we can safely truncate to.
1505  if (auto *FPExt = dyn_cast<FPExtInst>(V))
1506  return FPExt->getOperand(0)->getType();
1507 
1508  // If this value is a constant, return the constant in the smallest FP type
1509  // that can accurately represent it. This allows us to turn
1510  // (float)((double)X+2.0) into x+2.0f.
1511  if (auto *CFP = dyn_cast<ConstantFP>(V))
1512  if (Type *T = shrinkFPConstant(CFP))
1513  return T;
1514 
1515  // Try to shrink a vector of FP constants.
1516  if (Type *T = shrinkFPConstantVector(V))
1517  return T;
1518 
1519  return V->getType();
1520 }
1521 
1523  if (Instruction *I = commonCastTransforms(FPT))
1524  return I;
1525 
1526  // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
1527  // simplify this expression to avoid one or more of the trunc/extend
1528  // operations if we can do so without changing the numerical results.
1529  //
1530  // The exact manner in which the widths of the operands interact to limit
1531  // what we can and cannot do safely varies from operation to operation, and
1532  // is explained below in the various case statements.
1533  Type *Ty = FPT.getType();
1534  auto *BO = dyn_cast<BinaryOperator>(FPT.getOperand(0));
1535  if (BO && BO->hasOneUse()) {
1536  Type *LHSMinType = getMinimumFPType(BO->getOperand(0));
1537  Type *RHSMinType = getMinimumFPType(BO->getOperand(1));
1538  unsigned OpWidth = BO->getType()->getFPMantissaWidth();
1539  unsigned LHSWidth = LHSMinType->getFPMantissaWidth();
1540  unsigned RHSWidth = RHSMinType->getFPMantissaWidth();
1541  unsigned SrcWidth = std::max(LHSWidth, RHSWidth);
1542  unsigned DstWidth = Ty->getFPMantissaWidth();
1543  switch (BO->getOpcode()) {
1544  default: break;
1545  case Instruction::FAdd:
1546  case Instruction::FSub:
1547  // For addition and subtraction, the infinitely precise result can
1548  // essentially be arbitrarily wide; proving that double rounding
1549  // will not occur because the result of OpI is exact (as we will for
1550  // FMul, for example) is hopeless. However, we *can* nonetheless
1551  // frequently know that double rounding cannot occur (or that it is
1552  // innocuous) by taking advantage of the specific structure of
1553  // infinitely-precise results that admit double rounding.
1554  //
1555  // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
1556  // to represent both sources, we can guarantee that the double
1557  // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
1558  // "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
1559  // for proof of this fact).
1560  //
1561  // Note: Figueroa does not consider the case where DstFormat !=
1562  // SrcFormat. It's possible (likely even!) that this analysis
1563  // could be tightened for those cases, but they are rare (the main
1564  // case of interest here is (float)((double)float + float)).
1565  if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) {
1566  Value *LHS = Builder.CreateFPTrunc(BO->getOperand(0), Ty);
1567  Value *RHS = Builder.CreateFPTrunc(BO->getOperand(1), Ty);
1568  Instruction *RI = BinaryOperator::Create(BO->getOpcode(), LHS, RHS);
1569  RI->copyFastMathFlags(BO);
1570  return RI;
1571  }
1572  break;
1573  case Instruction::FMul:
1574  // For multiplication, the infinitely precise result has at most
1575  // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
1576  // that such a value can be exactly represented, then no double
1577  // rounding can possibly occur; we can safely perform the operation
1578  // in the destination format if it can represent both sources.
1579  if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) {
1580  Value *LHS = Builder.CreateFPTrunc(BO->getOperand(0), Ty);
1581  Value *RHS = Builder.CreateFPTrunc(BO->getOperand(1), Ty);
1582  return BinaryOperator::CreateFMulFMF(LHS, RHS, BO);
1583  }
1584  break;
1585  case Instruction::FDiv:
1586  // For division, we use again use the bound from Figueroa's
1587  // dissertation. I am entirely certain that this bound can be
1588  // tightened in the unbalanced operand case by an analysis based on
1589  // the diophantine rational approximation bound, but the well-known
1590  // condition used here is a good conservative first pass.
1591  // TODO: Tighten bound via rigorous analysis of the unbalanced case.
1592  if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) {
1593  Value *LHS = Builder.CreateFPTrunc(BO->getOperand(0), Ty);
1594  Value *RHS = Builder.CreateFPTrunc(BO->getOperand(1), Ty);
1595  return BinaryOperator::CreateFDivFMF(LHS, RHS, BO);
1596  }
1597  break;
1598  case Instruction::FRem: {
1599  // Remainder is straightforward. Remainder is always exact, so the
1600  // type of OpI doesn't enter into things at all. We simply evaluate
1601  // in whichever source type is larger, then convert to the
1602  // destination type.
1603  if (SrcWidth == OpWidth)
1604  break;
1605  Value *LHS, *RHS;
1606  if (LHSWidth == SrcWidth) {
1607  LHS = Builder.CreateFPTrunc(BO->getOperand(0), LHSMinType);
1608  RHS = Builder.CreateFPTrunc(BO->getOperand(1), LHSMinType);
1609  } else {
1610  LHS = Builder.CreateFPTrunc(BO->getOperand(0), RHSMinType);
1611  RHS = Builder.CreateFPTrunc(BO->getOperand(1), RHSMinType);
1612  }
1613 
1614  Value *ExactResult = Builder.CreateFRemFMF(LHS, RHS, BO);
1615  return CastInst::CreateFPCast(ExactResult, Ty);
1616  }
1617  }
1618  }
1619 
1620  // (fptrunc (fneg x)) -> (fneg (fptrunc x))
1621  Value *X;
1623  if (Op && Op->hasOneUse()) {
1624  if (match(Op, m_FNeg(m_Value(X)))) {
1625  Value *InnerTrunc = Builder.CreateFPTrunc(X, Ty);
1626 
1627  // FIXME: Once we're sure that unary FNeg optimizations are on par with
1628  // binary FNeg, this should always return a unary operator.
1629  if (isa<BinaryOperator>(Op))
1630  return BinaryOperator::CreateFNegFMF(InnerTrunc, Op);
1631  return UnaryOperator::CreateFNegFMF(InnerTrunc, Op);
1632  }
1633  }
1634 
1635  if (auto *II = dyn_cast<IntrinsicInst>(FPT.getOperand(0))) {
1636  switch (II->getIntrinsicID()) {
1637  default: break;
1638  case Intrinsic::ceil:
1639  case Intrinsic::fabs:
1640  case Intrinsic::floor:
1641  case Intrinsic::nearbyint:
1642  case Intrinsic::rint:
1643  case Intrinsic::round:
1644  case Intrinsic::trunc: {
1645  Value *Src = II->getArgOperand(0);
1646  if (!Src->hasOneUse())
1647  break;
1648 
1649  // Except for fabs, this transformation requires the input of the unary FP
1650  // operation to be itself an fpext from the type to which we're
1651  // truncating.
1652  if (II->getIntrinsicID() != Intrinsic::fabs) {
1653  FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Src);
1654  if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty)
1655  break;
1656  }
1657 
1658  // Do unary FP operation on smaller type.
1659  // (fptrunc (fabs x)) -> (fabs (fptrunc x))
1660  Value *InnerTrunc = Builder.CreateFPTrunc(Src, Ty);
1661  Function *Overload = Intrinsic::getDeclaration(FPT.getModule(),
1662  II->getIntrinsicID(), Ty);
1664  II->getOperandBundlesAsDefs(OpBundles);
1665  CallInst *NewCI =
1666  CallInst::Create(Overload, {InnerTrunc}, OpBundles, II->getName());
1667  NewCI->copyFastMathFlags(II);
1668  return NewCI;
1669  }
1670  }
1671  }
1672 
1673  if (Instruction *I = shrinkInsertElt(FPT, Builder))
1674  return I;
1675 
1676  return nullptr;
1677 }
1678 
1680  return commonCastTransforms(CI);
1681 }
1682 
1683 // fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
1684 // This is safe if the intermediate type has enough bits in its mantissa to
1685 // accurately represent all values of X. For example, this won't work with
1686 // i64 -> float -> i64.
1688  if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0)))
1689  return nullptr;
1690  Instruction *OpI = cast<Instruction>(FI.getOperand(0));
1691 
1692  Value *SrcI = OpI->getOperand(0);
1693  Type *FITy = FI.getType();
1694  Type *OpITy = OpI->getType();
1695  Type *SrcTy = SrcI->getType();
1696  bool IsInputSigned = isa<SIToFPInst>(OpI);
1697  bool IsOutputSigned = isa<FPToSIInst>(FI);
1698 
1699  // We can safely assume the conversion won't overflow the output range,
1700  // because (for example) (uint8_t)18293.f is undefined behavior.
1701 
1702  // Since we can assume the conversion won't overflow, our decision as to
1703  // whether the input will fit in the float should depend on the minimum
1704  // of the input range and output range.
1705 
1706  // This means this is also safe for a signed input and unsigned output, since
1707  // a negative input would lead to undefined behavior.
1708  int InputSize = (int)SrcTy->getScalarSizeInBits() - IsInputSigned;
1709  int OutputSize = (int)FITy->getScalarSizeInBits() - IsOutputSigned;
1710  int ActualSize = std::min(InputSize, OutputSize);
1711 
1712  if (ActualSize <= OpITy->getFPMantissaWidth()) {
1713  if (FITy->getScalarSizeInBits() > SrcTy->getScalarSizeInBits()) {
1714  if (IsInputSigned && IsOutputSigned)
1715  return new SExtInst(SrcI, FITy);
1716  return new ZExtInst(SrcI, FITy);
1717  }
1718  if (FITy->getScalarSizeInBits() < SrcTy->getScalarSizeInBits())
1719  return new TruncInst(SrcI, FITy);
1720  if (SrcTy == FITy)
1721  return replaceInstUsesWith(FI, SrcI);
1722  return new BitCastInst(SrcI, FITy);
1723  }
1724  return nullptr;
1725 }
1726 
1728  Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1729  if (!OpI)
1730  return commonCastTransforms(FI);
1731 
1732  if (Instruction *I = FoldItoFPtoI(FI))
1733  return I;
1734 
1735  return commonCastTransforms(FI);
1736 }
1737 
1739  Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1740  if (!OpI)
1741  return commonCastTransforms(FI);
1742 
1743  if (Instruction *I = FoldItoFPtoI(FI))
1744  return I;
1745 
1746  return commonCastTransforms(FI);
1747 }
1748 
1750  return commonCastTransforms(CI);
1751 }
1752 
1754  return commonCastTransforms(CI);
1755 }
1756 
1758  // If the source integer type is not the intptr_t type for this target, do a
1759  // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
1760  // cast to be exposed to other transforms.
1761  unsigned AS = CI.getAddressSpace();
1762  if (CI.getOperand(0)->getType()->getScalarSizeInBits() !=
1763  DL.getPointerSizeInBits(AS)) {
1764  Type *Ty = DL.getIntPtrType(CI.getContext(), AS);
1765  if (CI.getType()->isVectorTy()) // Handle vectors of pointers.
1766  Ty = VectorType::get(Ty, CI.getType()->getVectorNumElements());
1767 
1768  Value *P = Builder.CreateZExtOrTrunc(CI.getOperand(0), Ty);
1769  return new IntToPtrInst(P, CI.getType());
1770  }
1771 
1772  if (Instruction *I = commonCastTransforms(CI))
1773  return I;
1774 
1775  return nullptr;
1776 }
1777 
1778 /// Implement the transforms for cast of pointer (bitcast/ptrtoint)
1780  Value *Src = CI.getOperand(0);
1781 
1782  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
1783  // If casting the result of a getelementptr instruction with no offset, turn
1784  // this into a cast of the original pointer!
1785  if (GEP->hasAllZeroIndices() &&
1786  // If CI is an addrspacecast and GEP changes the poiner type, merging
1787  // GEP into CI would undo canonicalizing addrspacecast with different
1788  // pointer types, causing infinite loops.
1789  (!isa<AddrSpaceCastInst>(CI) ||
1790  GEP->getType() == GEP->getPointerOperandType())) {
1791  // Changing the cast operand is usually not a good idea but it is safe
1792  // here because the pointer operand is being replaced with another
1793  // pointer operand so the opcode doesn't need to change.
1794  Worklist.Add(GEP);
1795  CI.setOperand(0, GEP->getOperand(0));
1796  return &CI;
1797  }
1798  }
1799 
1800  return commonCastTransforms(CI);
1801 }
1802 
1804  // If the destination integer type is not the intptr_t type for this target,
1805  // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
1806  // to be exposed to other transforms.
1807 
1808  Type *Ty = CI.getType();
1809  unsigned AS = CI.getPointerAddressSpace();
1810 
1811  if (Ty->getScalarSizeInBits() == DL.getIndexSizeInBits(AS))
1812  return commonPointerCastTransforms(CI);
1813 
1814  Type *PtrTy = DL.getIntPtrType(CI.getContext(), AS);
1815  if (Ty->isVectorTy()) // Handle vectors of pointers.
1816  PtrTy = VectorType::get(PtrTy, Ty->getVectorNumElements());
1817 
1818  Value *P = Builder.CreatePtrToInt(CI.getOperand(0), PtrTy);
1819  return CastInst::CreateIntegerCast(P, Ty, /*isSigned=*/false);
1820 }
1821 
1822 /// This input value (which is known to have vector type) is being zero extended
1823 /// or truncated to the specified vector type.
1824 /// Try to replace it with a shuffle (and vector/vector bitcast) if possible.
1825 ///
1826 /// The source and destination vector types may have different element types.
1828  InstCombiner &IC) {
1829  // We can only do this optimization if the output is a multiple of the input
1830  // element size, or the input is a multiple of the output element size.
1831  // Convert the input type to have the same element type as the output.
1832  VectorType *SrcTy = cast<VectorType>(InVal->getType());
1833 
1834  if (SrcTy->getElementType() != DestTy->getElementType()) {
1835  // The input types don't need to be identical, but for now they must be the
1836  // same size. There is no specific reason we couldn't handle things like
1837  // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
1838  // there yet.
1839  if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
1841  return nullptr;
1842 
1843  SrcTy = VectorType::get(DestTy->getElementType(), SrcTy->getNumElements());
1844  InVal = IC.Builder.CreateBitCast(InVal, SrcTy);
1845  }
1846 
1847  // Now that the element types match, get the shuffle mask and RHS of the
1848  // shuffle to use, which depends on whether we're increasing or decreasing the
1849  // size of the input.
1850  SmallVector<uint32_t, 16> ShuffleMask;
1851  Value *V2;
1852 
1853  if (SrcTy->getNumElements() > DestTy->getNumElements()) {
1854  // If we're shrinking the number of elements, just shuffle in the low
1855  // elements from the input and use undef as the second shuffle input.
1856  V2 = UndefValue::get(SrcTy);
1857  for (unsigned i = 0, e = DestTy->getNumElements(); i != e; ++i)
1858  ShuffleMask.push_back(i);
1859 
1860  } else {
1861  // If we're increasing the number of elements, shuffle in all of the
1862  // elements from InVal and fill the rest of the result elements with zeros
1863  // from a constant zero.
1864  V2 = Constant::getNullValue(SrcTy);
1865  unsigned SrcElts = SrcTy->getNumElements();
1866  for (unsigned i = 0, e = SrcElts; i != e; ++i)
1867  ShuffleMask.push_back(i);
1868 
1869  // The excess elements reference the first element of the zero input.
1870  for (unsigned i = 0, e = DestTy->getNumElements()-SrcElts; i != e; ++i)
1871  ShuffleMask.push_back(SrcElts);
1872  }
1873 
1874  return new ShuffleVectorInst(InVal, V2,
1876  ShuffleMask));
1877 }
1878 
1879 static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
1880  return Value % Ty->getPrimitiveSizeInBits() == 0;
1881 }
1882 
1883 static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
1884  return Value / Ty->getPrimitiveSizeInBits();
1885 }
1886 
1887 /// V is a value which is inserted into a vector of VecEltTy.
1888 /// Look through the value to see if we can decompose it into
1889 /// insertions into the vector. See the example in the comment for
1890 /// OptimizeIntegerToVectorInsertions for the pattern this handles.
1891 /// The type of V is always a non-zero multiple of VecEltTy's size.
1892 /// Shift is the number of bits between the lsb of V and the lsb of
1893 /// the vector.
1894 ///
1895 /// This returns false if the pattern can't be matched or true if it can,
1896 /// filling in Elements with the elements found here.
1897 static bool collectInsertionElements(Value *V, unsigned Shift,
1898  SmallVectorImpl<Value *> &Elements,
1899  Type *VecEltTy, bool isBigEndian) {
1900  assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
1901  "Shift should be a multiple of the element type size");
1902 
1903  // Undef values never contribute useful bits to the result.
1904  if (isa<UndefValue>(V)) return true;
1905 
1906  // If we got down to a value of the right type, we win, try inserting into the
1907  // right element.
1908  if (V->getType() == VecEltTy) {
1909  // Inserting null doesn't actually insert any elements.
1910  if (Constant *C = dyn_cast<Constant>(V))
1911  if (C->isNullValue())
1912  return true;
1913 
1914  unsigned ElementIndex = getTypeSizeIndex(Shift, VecEltTy);
1915  if (isBigEndian)
1916  ElementIndex = Elements.size() - ElementIndex - 1;
1917 
1918  // Fail if multiple elements are inserted into this slot.
1919  if (Elements[ElementIndex])
1920  return false;
1921 
1922  Elements[ElementIndex] = V;
1923  return true;
1924  }
1925 
1926  if (Constant *C = dyn_cast<Constant>(V)) {
1927  // Figure out the # elements this provides, and bitcast it or slice it up
1928  // as required.
1929  unsigned NumElts = getTypeSizeIndex(C->getType()->getPrimitiveSizeInBits(),
1930  VecEltTy);
1931  // If the constant is the size of a vector element, we just need to bitcast
1932  // it to the right type so it gets properly inserted.
1933  if (NumElts == 1)
1935  Shift, Elements, VecEltTy, isBigEndian);
1936 
1937  // Okay, this is a constant that covers multiple elements. Slice it up into
1938  // pieces and insert each element-sized piece into the vector.
1939  if (!isa<IntegerType>(C->getType()))
1942  unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
1943  Type *ElementIntTy = IntegerType::get(C->getContext(), ElementSize);
1944 
1945  for (unsigned i = 0; i != NumElts; ++i) {
1946  unsigned ShiftI = Shift+i*ElementSize;
1948  ShiftI));
1949  Piece = ConstantExpr::getTrunc(Piece, ElementIntTy);
1950  if (!collectInsertionElements(Piece, ShiftI, Elements, VecEltTy,
1951  isBigEndian))
1952  return false;
1953  }
1954  return true;
1955  }
1956 
1957  if (!V->hasOneUse()) return false;
1958 
1960  if (!I) return false;
1961  switch (I->getOpcode()) {
1962  default: return false; // Unhandled case.
1963  case Instruction::BitCast:
1964  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1965  isBigEndian);
1966  case Instruction::ZExt:
1967  if (!isMultipleOfTypeSize(
1969  VecEltTy))
1970  return false;
1971  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1972  isBigEndian);
1973  case Instruction::Or:
1974  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1975  isBigEndian) &&
1976  collectInsertionElements(I->getOperand(1), Shift, Elements, VecEltTy,
1977  isBigEndian);
1978  case Instruction::Shl: {
1979  // Must be shifting by a constant that is a multiple of the element size.
1981  if (!CI) return false;
1982  Shift += CI->getZExtValue();
1983  if (!isMultipleOfTypeSize(Shift, VecEltTy)) return false;
1984  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1985  isBigEndian);
1986  }
1987 
1988  }
1989 }
1990 
1991 
1992 /// If the input is an 'or' instruction, we may be doing shifts and ors to
1993 /// assemble the elements of the vector manually.
1994 /// Try to rip the code out and replace it with insertelements. This is to
1995 /// optimize code like this:
1996 ///
1997 /// %tmp37 = bitcast float %inc to i32
1998 /// %tmp38 = zext i32 %tmp37 to i64
1999 /// %tmp31 = bitcast float %inc5 to i32
2000 /// %tmp32 = zext i32 %tmp31 to i64
2001 /// %tmp33 = shl i64 %tmp32, 32
2002 /// %ins35 = or i64 %tmp33, %tmp38
2003 /// %tmp43 = bitcast i64 %ins35 to <2 x float>
2004 ///
2005 /// Into two insertelements that do "buildvector{%inc, %inc5}".
2007  InstCombiner &IC) {
2008  VectorType *DestVecTy = cast<VectorType>(CI.getType());
2009  Value *IntInput = CI.getOperand(0);
2010 
2011  SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
2012  if (!collectInsertionElements(IntInput, 0, Elements,
2013  DestVecTy->getElementType(),
2014  IC.getDataLayout().isBigEndian()))
2015  return nullptr;
2016 
2017  // If we succeeded, we know that all of the element are specified by Elements
2018  // or are zero if Elements has a null entry. Recast this as a set of
2019  // insertions.
2020  Value *Result = Constant::getNullValue(CI.getType());
2021  for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
2022  if (!Elements[i]) continue; // Unset element.
2023 
2024  Result = IC.Builder.CreateInsertElement(Result, Elements[i],
2025  IC.Builder.getInt32(i));
2026  }
2027 
2028  return Result;
2029 }
2030 
2031 /// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
2032 /// vector followed by extract element. The backend tends to handle bitcasts of
2033 /// vectors better than bitcasts of scalars because vector registers are
2034 /// usually not type-specific like scalar integer or scalar floating-point.
2036  InstCombiner &IC) {
2037  // TODO: Create and use a pattern matcher for ExtractElementInst.
2038  auto *ExtElt = dyn_cast<ExtractElementInst>(BitCast.getOperand(0));
2039  if (!ExtElt || !ExtElt->hasOneUse())
2040  return nullptr;
2041 
2042  // The bitcast must be to a vectorizable type, otherwise we can't make a new
2043  // type to extract from.
2044  Type *DestType = BitCast.getType();
2045  if (!VectorType::isValidElementType(DestType))
2046  return nullptr;
2047 
2048  unsigned NumElts = ExtElt->getVectorOperandType()->getNumElements();
2049  auto *NewVecType = VectorType::get(DestType, NumElts);
2050  auto *NewBC = IC.Builder.CreateBitCast(ExtElt->getVectorOperand(),
2051  NewVecType, "bc");
2052  return ExtractElementInst::Create(NewBC, ExtElt->getIndexOperand());
2053 }
2054 
2055 /// Change the type of a bitwise logic operation if we can eliminate a bitcast.
2057  InstCombiner::BuilderTy &Builder) {
2058  Type *DestTy = BitCast.getType();
2059  BinaryOperator *BO;
2060  if (!DestTy->isIntOrIntVectorTy() ||
2061  !match(BitCast.getOperand(0), m_OneUse(m_BinOp(BO))) ||
2062  !BO->isBitwiseLogicOp())
2063  return nullptr;
2064 
2065  // FIXME: This transform is restricted to vector types to avoid backend
2066  // problems caused by creating potentially illegal operations. If a fix-up is
2067  // added to handle that situation, we can remove this check.
2068  if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy())
2069  return nullptr;
2070 
2071  Value *X;
2072  if (match(BO->getOperand(0), m_OneUse(m_BitCast(m_Value(X)))) &&
2073  X->getType() == DestTy && !isa<Constant>(X)) {
2074  // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y))
2075  Value *CastedOp1 = Builder.CreateBitCast(BO->getOperand(1), DestTy);
2076  return BinaryOperator::Create(BO->getOpcode(), X, CastedOp1);
2077  }
2078 
2079  if (match(BO->getOperand(1), m_OneUse(m_BitCast(m_Value(X)))) &&
2080  X->getType() == DestTy && !isa<Constant>(X)) {
2081  // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X)
2082  Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
2083  return BinaryOperator::Create(BO->getOpcode(), CastedOp0, X);
2084  }
2085 
2086  // Canonicalize vector bitcasts to come before vector bitwise logic with a
2087  // constant. This eases recognition of special constants for later ops.
2088  // Example:
2089  // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
2090  Constant *C;
2091  if (match(BO->getOperand(1), m_Constant(C))) {
2092  // bitcast (logic X, C) --> logic (bitcast X, C')
2093  Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
2094  Value *CastedC = ConstantExpr::getBitCast(C, DestTy);
2095  return BinaryOperator::Create(BO->getOpcode(), CastedOp0, CastedC);
2096  }
2097 
2098  return nullptr;
2099 }
2100 
2101 /// Change the type of a select if we can eliminate a bitcast.
2103  InstCombiner::BuilderTy &Builder) {
2104  Value *Cond, *TVal, *FVal;
2105  if (!match(BitCast.getOperand(0),
2106  m_OneUse(m_Select(m_Value(Cond), m_Value(TVal), m_Value(FVal)))))
2107  return nullptr;
2108 
2109  // A vector select must maintain the same number of elements in its operands.
2110  Type *CondTy = Cond->getType();
2111  Type *DestTy = BitCast.getType();
2112  if (CondTy->isVectorTy()) {
2113  if (!DestTy->isVectorTy())
2114  return nullptr;
2115  if (DestTy->getVectorNumElements() != CondTy->getVectorNumElements())
2116  return nullptr;
2117  }
2118 
2119  // FIXME: This transform is restricted from changing the select between
2120  // scalars and vectors to avoid backend problems caused by creating
2121  // potentially illegal operations. If a fix-up is added to handle that
2122  // situation, we can remove this check.
2123  if (DestTy->isVectorTy() != TVal->getType()->isVectorTy())
2124  return nullptr;
2125 
2126  auto *Sel = cast<Instruction>(BitCast.getOperand(0));
2127  Value *X;
2128  if (match(TVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy &&
2129  !isa<Constant>(X)) {
2130  // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y))
2131  Value *CastedVal = Builder.CreateBitCast(FVal, DestTy);
2132  return SelectInst::Create(Cond, X, CastedVal, "", nullptr, Sel);
2133  }
2134 
2135  if (match(FVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy &&
2136  !isa<Constant>(X)) {
2137  // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X)
2138  Value *CastedVal = Builder.CreateBitCast(TVal, DestTy);
2139  return SelectInst::Create(Cond, CastedVal, X, "", nullptr, Sel);
2140  }
2141 
2142  return nullptr;
2143 }
2144 
2145 /// Check if all users of CI are StoreInsts.
2146 static bool hasStoreUsersOnly(CastInst &CI) {
2147  for (User *U : CI.users()) {
2148  if (!isa<StoreInst>(U))
2149  return false;
2150  }
2151  return true;
2152 }
2153 
2154 /// This function handles following case
2155 ///
2156 /// A -> B cast
2157 /// PHI
2158 /// B -> A cast
2159 ///
2160 /// All the related PHI nodes can be replaced by new PHI nodes with type A.
2161 /// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
2162 Instruction *InstCombiner::optimizeBitCastFromPhi(CastInst &CI, PHINode *PN) {
2163  // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp.
2164  if (hasStoreUsersOnly(CI))
2165  return nullptr;
2166 
2167  Value *Src = CI.getOperand(0);
2168  Type *SrcTy = Src->getType(); // Type B
2169  Type *DestTy = CI.getType(); // Type A
2170 
2171  SmallVector<PHINode *, 4> PhiWorklist;
2172  SmallSetVector<PHINode *, 4> OldPhiNodes;
2173 
2174  // Find all of the A->B casts and PHI nodes.
2175  // We need to inspect all related PHI nodes, but PHIs can be cyclic, so
2176  // OldPhiNodes is used to track all known PHI nodes, before adding a new
2177  // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
2178  PhiWorklist.push_back(PN);
2179  OldPhiNodes.insert(PN);
2180  while (!PhiWorklist.empty()) {
2181  auto *OldPN = PhiWorklist.pop_back_val();
2182  for (Value *IncValue : OldPN->incoming_values()) {
2183  if (isa<Constant>(IncValue))
2184  continue;
2185 
2186  if (auto *LI = dyn_cast<LoadInst>(IncValue)) {
2187  // If there is a sequence of one or more load instructions, each loaded
2188  // value is used as address of later load instruction, bitcast is
2189  // necessary to change the value type, don't optimize it. For
2190  // simplicity we give up if the load address comes from another load.
2191  Value *Addr = LI->getOperand(0);
2192  if (Addr == &CI || isa<LoadInst>(Addr))
2193  return nullptr;
2194  if (LI->hasOneUse() && LI->isSimple())
2195  continue;
2196  // If a LoadInst has more than one use, changing the type of loaded
2197  // value may create another bitcast.
2198  return nullptr;
2199  }
2200 
2201  if (auto *PNode = dyn_cast<PHINode>(IncValue)) {
2202  if (OldPhiNodes.insert(PNode))
2203  PhiWorklist.push_back(PNode);
2204  continue;
2205  }
2206 
2207  auto *BCI = dyn_cast<BitCastInst>(IncValue);
2208  // We can't handle other instructions.
2209  if (!BCI)
2210  return nullptr;
2211 
2212  // Verify it's a A->B cast.
2213  Type *TyA = BCI->getOperand(0)->getType();
2214  Type *TyB = BCI->getType();
2215  if (TyA != DestTy || TyB != SrcTy)
2216  return nullptr;
2217  }
2218  }
2219 
2220  // For each old PHI node, create a corresponding new PHI node with a type A.
2222  for (auto *OldPN : OldPhiNodes) {
2223  Builder.SetInsertPoint(OldPN);
2224  PHINode *NewPN = Builder.CreatePHI(DestTy, OldPN->getNumOperands());
2225  NewPNodes[OldPN] = NewPN;
2226  }
2227 
2228  // Fill in the operands of new PHI nodes.
2229  for (auto *OldPN : OldPhiNodes) {
2230  PHINode *NewPN = NewPNodes[OldPN];
2231  for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
2232  Value *V = OldPN->getOperand(j);
2233  Value *NewV = nullptr;
2234  if (auto *C = dyn_cast<Constant>(V)) {
2235  NewV = ConstantExpr::getBitCast(C, DestTy);
2236  } else if (auto *LI = dyn_cast<LoadInst>(V)) {
2237  Builder.SetInsertPoint(LI->getNextNode());
2238  NewV = Builder.CreateBitCast(LI, DestTy);
2239  Worklist.Add(LI);
2240  } else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
2241  NewV = BCI->getOperand(0);
2242  } else if (auto *PrevPN = dyn_cast<PHINode>(V)) {
2243  NewV = NewPNodes[PrevPN];
2244  }
2245  assert(NewV);
2246  NewPN->addIncoming(NewV, OldPN->getIncomingBlock(j));
2247  }
2248  }
2249 
2250  // Traverse all accumulated PHI nodes and process its users,
2251  // which are Stores and BitcCasts. Without this processing
2252  // NewPHI nodes could be replicated and could lead to extra
2253  // moves generated after DeSSA.
2254  // If there is a store with type B, change it to type A.
2255 
2256 
2257  // Replace users of BitCast B->A with NewPHI. These will help
2258  // later to get rid off a closure formed by OldPHI nodes.
2259  Instruction *RetVal = nullptr;
2260  for (auto *OldPN : OldPhiNodes) {
2261  PHINode *NewPN = NewPNodes[OldPN];
2262  for (User *V : OldPN->users()) {
2263  if (auto *SI = dyn_cast<StoreInst>(V)) {
2264  if (SI->isSimple() && SI->getOperand(0) == OldPN) {
2265  Builder.SetInsertPoint(SI);
2266  auto *NewBC =
2267  cast<BitCastInst>(Builder.CreateBitCast(NewPN, SrcTy));
2268  SI->setOperand(0, NewBC);
2269  Worklist.Add(SI);
2270  assert(hasStoreUsersOnly(*NewBC));
2271  }
2272  }
2273  else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
2274  // Verify it's a B->A cast.
2275  Type *TyB = BCI->getOperand(0)->getType();
2276  Type *TyA = BCI->getType();
2277  if (TyA == DestTy && TyB == SrcTy) {
2278  Instruction *I = replaceInstUsesWith(*BCI, NewPN);
2279  if (BCI == &CI)
2280  RetVal = I;
2281  }
2282  }
2283  }
2284  }
2285 
2286  return RetVal;
2287 }
2288 
2290  // If the operands are integer typed then apply the integer transforms,
2291  // otherwise just apply the common ones.
2292  Value *Src = CI.getOperand(0);
2293  Type *SrcTy = Src->getType();
2294  Type *DestTy = CI.getType();
2295 
2296  // Get rid of casts from one type to the same type. These are useless and can
2297  // be replaced by the operand.
2298  if (DestTy == Src->getType())
2299  return replaceInstUsesWith(CI, Src);
2300 
2301  if (PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
2302  PointerType *SrcPTy = cast<PointerType>(SrcTy);
2303  Type *DstElTy = DstPTy->getElementType();
2304  Type *SrcElTy = SrcPTy->getElementType();
2305 
2306  // Casting pointers between the same type, but with different address spaces
2307  // is an addrspace cast rather than a bitcast.
2308  if ((DstElTy == SrcElTy) &&
2309  (DstPTy->getAddressSpace() != SrcPTy->getAddressSpace()))
2310  return new AddrSpaceCastInst(Src, DestTy);
2311 
2312  // If we are casting a alloca to a pointer to a type of the same
2313  // size, rewrite the allocation instruction to allocate the "right" type.
2314  // There is no need to modify malloc calls because it is their bitcast that
2315  // needs to be cleaned up.
2316  if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
2317  if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
2318  return V;
2319 
2320  // When the type pointed to is not sized the cast cannot be
2321  // turned into a gep.
2322  Type *PointeeType =
2323  cast<PointerType>(Src->getType()->getScalarType())->getElementType();
2324  if (!PointeeType->isSized())
2325  return nullptr;
2326 
2327  // If the source and destination are pointers, and this cast is equivalent
2328  // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
2329  // This can enhance SROA and other transforms that want type-safe pointers.
2330  unsigned NumZeros = 0;
2331  while (SrcElTy != DstElTy &&
2332  isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
2333  SrcElTy->getNumContainedTypes() /* not "{}" */) {
2334  SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(0U);
2335  ++NumZeros;
2336  }
2337 
2338  // If we found a path from the src to dest, create the getelementptr now.
2339  if (SrcElTy == DstElTy) {
2340  SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder.getInt32(0));
2342  GetElementPtrInst::Create(SrcPTy->getElementType(), Src, Idxs);
2343 
2344  // If the source pointer is dereferenceable, then assume it points to an
2345  // allocated object and apply "inbounds" to the GEP.
2346  bool CanBeNull;
2347  if (Src->getPointerDereferenceableBytes(DL, CanBeNull)) {
2348  // In a non-default address space (not 0), a null pointer can not be
2349  // assumed inbounds, so ignore that case (dereferenceable_or_null).
2350  // The reason is that 'null' is not treated differently in these address
2351  // spaces, and we consequently ignore the 'gep inbounds' special case
2352  // for 'null' which allows 'inbounds' on 'null' if the indices are
2353  // zeros.
2354  if (SrcPTy->getAddressSpace() == 0 || !CanBeNull)
2355  GEP->setIsInBounds();
2356  }
2357  return GEP;
2358  }
2359  }
2360 
2361  if (VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
2362  if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) {
2363  Value *Elem = Builder.CreateBitCast(Src, DestVTy->getElementType());
2364  return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
2366  // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
2367  }
2368 
2369  if (isa<IntegerType>(SrcTy)) {
2370  // If this is a cast from an integer to vector, check to see if the input
2371  // is a trunc or zext of a bitcast from vector. If so, we can replace all
2372  // the casts with a shuffle and (potentially) a bitcast.
2373  if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) {
2374  CastInst *SrcCast = cast<CastInst>(Src);
2375  if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
2376  if (isa<VectorType>(BCIn->getOperand(0)->getType()))
2377  if (Instruction *I = optimizeVectorResize(BCIn->getOperand(0),
2378  cast<VectorType>(DestTy), *this))
2379  return I;
2380  }
2381 
2382  // If the input is an 'or' instruction, we may be doing shifts and ors to
2383  // assemble the elements of the vector manually. Try to rip the code out
2384  // and replace it with insertelements.
2385  if (Value *V = optimizeIntegerToVectorInsertions(CI, *this))
2386  return replaceInstUsesWith(CI, V);
2387  }
2388  }
2389 
2390  if (VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
2391  if (SrcVTy->getNumElements() == 1) {
2392  // If our destination is not a vector, then make this a straight
2393  // scalar-scalar cast.
2394  if (!DestTy->isVectorTy()) {
2395  Value *Elem =
2396  Builder.CreateExtractElement(Src,
2398  return CastInst::Create(Instruction::BitCast, Elem, DestTy);
2399  }
2400 
2401  // Otherwise, see if our source is an insert. If so, then use the scalar
2402  // component directly:
2403  // bitcast (inselt <1 x elt> V, X, 0) to <n x m> --> bitcast X to <n x m>
2404  if (auto *InsElt = dyn_cast<InsertElementInst>(Src))
2405  return new BitCastInst(InsElt->getOperand(1), DestTy);
2406  }
2407  }
2408 
2409  if (auto *Shuf = dyn_cast<ShuffleVectorInst>(Src)) {
2410  // Okay, we have (bitcast (shuffle ..)). Check to see if this is
2411  // a bitcast to a vector with the same # elts.
2412  Value *ShufOp0 = Shuf->getOperand(0);
2413  Value *ShufOp1 = Shuf->getOperand(1);
2414  unsigned NumShufElts = Shuf->getType()->getVectorNumElements();
2415  unsigned NumSrcVecElts = ShufOp0->getType()->getVectorNumElements();
2416  if (Shuf->hasOneUse() && DestTy->isVectorTy() &&
2417  DestTy->getVectorNumElements() == NumShufElts &&
2418  NumShufElts == NumSrcVecElts) {
2419  BitCastInst *Tmp;
2420  // If either of the operands is a cast from CI.getType(), then
2421  // evaluating the shuffle in the casted destination's type will allow
2422  // us to eliminate at least one cast.
2423  if (((Tmp = dyn_cast<BitCastInst>(ShufOp0)) &&
2424  Tmp->getOperand(0)->getType() == DestTy) ||
2425  ((Tmp = dyn_cast<BitCastInst>(ShufOp1)) &&
2426  Tmp->getOperand(0)->getType() == DestTy)) {
2427  Value *LHS = Builder.CreateBitCast(ShufOp0, DestTy);
2428  Value *RHS = Builder.CreateBitCast(ShufOp1, DestTy);
2429  // Return a new shuffle vector. Use the same element ID's, as we
2430  // know the vector types match #elts.
2431  return new ShuffleVectorInst(LHS, RHS, Shuf->getOperand(2));
2432  }
2433  }
2434 
2435  // A bitcasted-to-scalar and byte-reversing shuffle is better recognized as
2436  // a byte-swap:
2437  // bitcast <N x i8> (shuf X, undef, <N, N-1,...0>) --> bswap (bitcast X)
2438  // TODO: We should match the related pattern for bitreverse.
2439  if (DestTy->isIntegerTy() &&
2440  DL.isLegalInteger(DestTy->getScalarSizeInBits()) &&
2441  SrcTy->getScalarSizeInBits() == 8 && NumShufElts % 2 == 0 &&
2442  Shuf->hasOneUse() && Shuf->isReverse()) {
2443  assert(ShufOp0->getType() == SrcTy && "Unexpected shuffle mask");
2444  assert(isa<UndefValue>(ShufOp1) && "Unexpected shuffle op");
2445  Function *Bswap =
2446  Intrinsic::getDeclaration(CI.getModule(), Intrinsic::bswap, DestTy);
2447  Value *ScalarX = Builder.CreateBitCast(ShufOp0, DestTy);
2448  return IntrinsicInst::Create(Bswap, { ScalarX });
2449  }
2450  }
2451 
2452  // Handle the A->B->A cast, and there is an intervening PHI node.
2453  if (PHINode *PN = dyn_cast<PHINode>(Src))
2454  if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
2455  return I;
2456 
2457  if (Instruction *I = canonicalizeBitCastExtElt(CI, *this))
2458  return I;
2459 
2460  if (Instruction *I = foldBitCastBitwiseLogic(CI, Builder))
2461  return I;
2462 
2463  if (Instruction *I = foldBitCastSelect(CI, Builder))
2464  return I;
2465 
2466  if (SrcTy->isPointerTy())
2467  return commonPointerCastTransforms(CI);
2468  return commonCastTransforms(CI);
2469 }
2470 
2472  // If the destination pointer element type is not the same as the source's
2473  // first do a bitcast to the destination type, and then the addrspacecast.
2474  // This allows the cast to be exposed to other transforms.
2475  Value *Src = CI.getOperand(0);
2476  PointerType *SrcTy = cast<PointerType>(Src->getType()->getScalarType());
2477  PointerType *DestTy = cast<PointerType>(CI.getType()->getScalarType());
2478 
2479  Type *DestElemTy = DestTy->getElementType();
2480  if (SrcTy->getElementType() != DestElemTy) {
2481  Type *MidTy = PointerType::get(DestElemTy, SrcTy->getAddressSpace());
2482  if (VectorType *VT = dyn_cast<VectorType>(CI.getType())) {
2483  // Handle vectors of pointers.
2484  MidTy = VectorType::get(MidTy, VT->getNumElements());
2485  }
2486 
2487  Value *NewBitCast = Builder.CreateBitCast(Src, MidTy);
2488  return new AddrSpaceCastInst(NewBitCast, CI.getType());
2489  }
2490 
2491  return commonPointerCastTransforms(CI);
2492 }
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:874
uint64_t CallInst * C
void computeKnownBits(const Value *V, KnownBits &Known, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, OptimizationRemarkEmitter *ORE=nullptr, bool UseInstrInfo=true)
Determine which bits of V are known to be either zero or one and return them in the KnownZero/KnownOn...
BinOpPred_match< LHS, RHS, is_right_shift_op > m_Shr(const LHS &L, const RHS &R)
Matches logical shift operations.
void copyFastMathFlags(FastMathFlags FMF)
Convenience function for transferring all fast-math flag values to this instruction, which must be an operator which supports these flags.
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:70
This class is the base class for the comparison instructions.
Definition: InstrTypes.h:722
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
static Type * getDoubleTy(LLVMContext &C)
Definition: Type.cpp:169
Type * getSrcTy() const
Return the source type, as a convenience.
Definition: InstrTypes.h:697
void addIncoming(Value *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
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
DiagnosticInfoOptimizationBase::Argument NV
This class represents lattice values for constants.
Definition: AllocatorList.h:23
BinaryOps getOpcode() const
Definition: InstrTypes.h:402
Instruction * visitBitCast(BitCastInst &CI)
bool isSized(SmallPtrSetImpl< Type *> *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:265
static CallInst * Create(FunctionType *Ty, Value *F, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
This class represents zero extension of integer types.
Instruction * commonCastTransforms(CastInst &CI)
Implement the transforms common to all CastInst visitors.
void push_back(const T &Elt)
Definition: SmallVector.h:211
static GetElementPtrInst * Create(Type *PointeeType, Value *Ptr, ArrayRef< Value *> IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Definition: Instructions.h:907
This class represents a function call, abstracting a target machine&#39;s calling convention.
static Type * shrinkFPConstant(ConstantFP *CFP)
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
static PointerType * get(Type *ElementType, unsigned AddressSpace)
This constructs a pointer to an object of the specified type in a numbered address space...
Definition: Type.cpp:637
static uint64_t round(uint64_t Acc, uint64_t Input)
Definition: xxhash.cpp:57
const Value * getTrueValue() const
BinaryOp_match< LHS, RHS, Instruction::AShr > m_AShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:904
This instruction constructs a fixed permutation of two input vectors.
static SelectInst * Create(Value *C, Value *S1, Value *S2, const Twine &NameStr="", Instruction *InsertBefore=nullptr, Instruction *MDFrom=nullptr)
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:743
static bool isEquality(Predicate P)
Return true if this predicate is either EQ or NE.
APInt trunc(unsigned width) const
Truncate to new width.
Definition: APInt.cpp:865
F(f)
This class represents a sign extension of integer types.
Hexagon Common GEP
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:230
static bool isBitwiseLogicOp(unsigned Opcode)
Determine if the Opcode is and/or/xor.
Definition: Instruction.h:175
Instruction * visitUIToFP(CastInst &CI)
cst_pred_ty< is_zero_int > m_ZeroInt()
Match an integer 0 or a vector with all elements equal to 0.
Definition: PatternMatch.h:391
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1517
BinOpPred_match< LHS, RHS, is_logical_shift_op > m_LogicalShift(const LHS &L, const RHS &R)
Matches logical shift operations.
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:289
Instruction * visitFPExt(CastInst &CI)
Instruction * FoldItoFPtoI(Instruction &FI)
unsigned countTrailingZeros() const
Count the number of trailing zero bits.
Definition: APInt.h:1640
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:47
static InsertElementInst * Create(Value *Vec, Value *NewElt, Value *Idx, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Instruction * visitFPToUI(FPToUIInst &FI)
This class represents a conversion between pointers from one address space to another.
static Constant * getIntegerCast(Constant *C, Type *Ty, bool isSigned)
Create a ZExt, Bitcast or Trunc for integer -> integer casts.
Definition: Constants.cpp:1644
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.
unsigned getAlignment() const
Return the alignment of the memory that is being allocated by the instruction.
Definition: Instructions.h:112
static bool hasStoreUsersOnly(CastInst &CI)
Check if all users of CI are StoreInsts.
static Type * getFloatTy(LLVMContext &C)
Definition: Type.cpp:168
This is the base class for all instructions that perform data casts.
Definition: InstrTypes.h:439
PointerType * getType() const
Overload to return most specific pointer type.
Definition: Instructions.h:96
&#39;undef&#39; values are things that do not have specified contents.
Definition: Constants.h:1285
static Constant * getLShr(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2328
static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear, InstCombiner &IC, Instruction *CxtI)
Determine if the specified value can be computed in the specified wider type and produce the same low...
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.
static bool canEvaluateTruncated(Value *V, Type *Ty, InstCombiner &IC, Instruction *CxtI)
Return true if we can evaluate the specified expression tree as type Ty instead of its larger type...
static Instruction * canonicalizeBitCastExtElt(BitCastInst &BitCast, InstCombiner &IC)
Canonicalize scalar bitcasts of extracted elements into a bitcast of the vector followed by extract e...
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.
Instruction * visitIntToPtr(IntToPtrInst &CI)
static Instruction * optimizeVectorResize(Value *InVal, VectorType *DestTy, InstCombiner &IC)
This input value (which is known to have vector type) is being zero extended or truncated to the spec...
Instruction * visitAddrSpaceCast(AddrSpaceCastInst &CI)
uint64_t getNumElements() const
For scalable vectors, this will return the minimum number of elements in the vector.
Definition: DerivedTypes.h:398
static Type * getPPC_FP128Ty(LLVMContext &C)
Definition: Type.cpp:174
static unsigned getTypeSizeIndex(unsigned Value, Type *Ty)
This class represents a cast from a pointer to an integer.
unsigned getPointerAddressSpace() const
Returns the address space of the pointer operand.
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
Value * CreateBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1963
static bool isMultipleOfTypeSize(unsigned Value, Type *Ty)
Instruction::CastOps getOpcode() const
Return the opcode of this CastInst.
Definition: InstrTypes.h:692
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:246
bool insert(const value_type &X)
Insert a new element into the SetVector.
Definition: SetVector.h:141
opStatus convert(const fltSemantics &ToSemantics, roundingMode RM, bool *losesInfo)
Definition: APFloat.cpp:4483
match_combine_or< LTy, RTy > m_CombineOr(const LTy &L, const RTy &R)
Combine two pattern matchers matching L || R.
Definition: PatternMatch.h:142
static BinaryOperator * CreateFMulFMF(Value *V1, Value *V2, Instruction *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:268
CastClass_match< OpTy, Instruction::ZExt > m_ZExt(const OpTy &Op)
Matches ZExt.
bool isUsedWithInAlloca() const
Return true if this alloca is used as an inalloca argument to a call.
Definition: Instructions.h:126
static bool isValidElementType(Type *ElemTy)
Return true if the specified type is valid as a element type.
Definition: Type.cpp:628
static bool collectInsertionElements(Value *V, unsigned Shift, SmallVectorImpl< Value *> &Elements, Type *VecEltTy, bool isBigEndian)
V is a value which is inserted into a vector of VecEltTy.
This class represents a no-op cast from one type to another.
class_match< ConstantInt > m_ConstantInt()
Match an arbitrary ConstantInt and ignore it.
Definition: PatternMatch.h:81
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:137
static APInt getBitsSetFrom(unsigned numBits, unsigned loBit)
Get a value with upper bits starting at loBit set.
Definition: APInt.h:623
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
int getFPMantissaWidth() const
Return the width of the mantissa of this type.
Definition: Type.cpp:138
This class represents a cast from floating point to signed integer.
static Value * optimizeIntegerToVectorInsertions(BitCastInst &CI, InstCombiner &IC)
If the input is an &#39;or&#39; instruction, we may be doing shifts and ors to assemble the elements of the v...
static const fltSemantics & IEEEdouble() LLVM_READNONE
Definition: APFloat.cpp:158
bool replaceAllDbgUsesWith(Instruction &From, Value &To, Instruction &DomPoint, DominatorTree &DT)
Point debug users of From to To or salvage them.
Definition: Local.cpp:1821
static Type * getMinimumFPType(Value *V)
Find the minimum FP type we can safely truncate to.
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:291
static Instruction * foldBitCastSelect(BitCastInst &BitCast, InstCombiner::BuilderTy &Builder)
Change the type of a select if we can eliminate a bitcast.
Function * getDeclaration(Module *M, ID id, ArrayRef< Type *> Tys=None)
Create or insert an LLVM Function declaration for an intrinsic, and return it.
Definition: Function.cpp:1093
This class represents a truncation of integer types.
Value * getOperand(unsigned i) const
Definition: User.h:169
Class to represent pointers.
Definition: DerivedTypes.h:579
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:307
const DataLayout & getDataLayout() const
static APInt getHighBitsSet(unsigned numBits, unsigned hiBitsSet)
Get a value with high bits set.
Definition: APInt.h:635
static Constant * getBitCast(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1804
an instruction for type-safe pointer arithmetic to access elements of arrays and structs ...
Definition: Instructions.h:881
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:61
#define P(N)
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 Instruction * foldBitCastBitwiseLogic(BitCastInst &BitCast, InstCombiner::BuilderTy &Builder)
Change the type of a bitwise logic operation if we can eliminate a bitcast.
This instruction inserts a single (scalar) element into a VectorType value.
bool isAllOnesValue() const
Determine if all bits are set.
Definition: APInt.h:395
static bool canNotEvaluateInType(Value *V, Type *Ty)
Filter out values that we can not evaluate in the destination type for free.
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:148
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
unsigned countPopulation() const
Count the number of bits set.
Definition: APInt.h:1666
constexpr bool isPowerOf2_32(uint32_t Value)
Return true if the argument is a power of two > 0.
Definition: MathExtras.h:465
TypeSize getPrimitiveSizeInBits() const LLVM_READONLY
Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:115
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
BinaryOp_match< LHS, RHS, Instruction::Or > m_Or(const LHS &L, const RHS &R)
Definition: PatternMatch.h:880
static Optional< bool > isBigEndian(const SmallVector< int64_t, 4 > &ByteOffsets, int64_t FirstOffset)
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1184
CastClass_match< OpTy, Instruction::BitCast > m_BitCast(const OpTy &Op)
Matches BitCast.
This is an important base class in LLVM.
Definition: Constant.h:41
unsigned getNumContainedTypes() const
Return the number of types in the derived type.
Definition: Type.h:342
void setUsedWithInAlloca(bool V)
Specify whether this alloca is used to represent the arguments to a call.
Definition: Instructions.h:131
bool isPointerTy() const
True if this is an instance of PointerType.
Definition: Type.h:224
ConstantFP - Floating Point Values [float, double].
Definition: Constants.h:263
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
BinaryOp_match< LHS, RHS, Instruction::Shl > m_Shl(const LHS &L, const RHS &R)
Definition: PatternMatch.h:892
static Value * decomposeSimpleLinearExpr(Value *Val, unsigned &Scale, uint64_t &Offset)
Analyze &#39;Val&#39;, seeing if it is a simple linear expression.
This instruction compares its operands according to the predicate given to the constructor.
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:732
Utility class for integer operators which may exhibit overflow - Add, Sub, Mul, and Shl...
Definition: Operator.h:66
constexpr double e
Definition: MathExtras.h:57
match_combine_or< CastClass_match< OpTy, Instruction::ZExt >, CastClass_match< OpTy, Instruction::SExt > > m_ZExtOrSExt(const OpTy &Op)
unsigned getAddressSpace() const
Return the address space of the Pointer type.
Definition: DerivedTypes.h:607
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:73
unsigned getAddressSpace() const
Returns the address space of this instruction&#39;s pointer type.
Class to represent integer types.
Definition: DerivedTypes.h:40
static bool fitsInFPType(ConstantFP *CFP, const fltSemantics &Sem)
Return a Constant* for the specified floating-point constant if it fits in the specified FP type with...
This class represents a cast from an integer to a pointer.
static Constant * getAllOnesValue(Type *Ty)
Definition: Constants.cpp:343
Instruction * visitFPToSI(FPToSIInst &FI)
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1446
const Value * getArraySize() const
Get the number of elements allocated.
Definition: Instructions.h:92
size_t size() const
Definition: SmallVector.h:52
Value * getIncomingValue(unsigned i) const
Return incoming value number x.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Value * CreateTrunc(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1873
deferredval_ty< Value > m_Deferred(Value *const &V)
A commutative-friendly version of m_Specific().
Definition: PatternMatch.h:600
Type * getAllocatedType() const
Return the type that is being allocated by the instruction.
Definition: Instructions.h:105
signed greater than
Definition: InstrTypes.h:759
const APFloat & getValueAPF() const
Definition: Constants.h:302
CastClass_match< OpTy, Instruction::SExt > m_SExt(const OpTy &Op)
Matches SExt.
static Type * getHalfTy(LLVMContext &C)
Definition: Type.cpp:167
bool isPtrOrPtrVectorTy() const
Return true if this is a pointer type or a vector of pointer types.
Definition: Type.h:227
static IntegerType * get(LLVMContext &C, unsigned NumBits)
This static method is the primary way of constructing an IntegerType.
Definition: Type.cpp:244
static const fltSemantics & IEEEsingle() LLVM_READNONE
Definition: APFloat.cpp:155
static CastInst * CreateIntegerCast(Value *S, Type *Ty, bool isSigned, const Twine &Name="", Instruction *InsertBefore=nullptr)
Create a ZExt, BitCast, or Trunc for int -> int casts.
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:297
BinaryOp_match< LHS, RHS, Instruction::Or, true > m_c_Or(const LHS &L, const RHS &R)
Matches an Or with LHS and RHS in either order.
This is the shared class of boolean and integer constants.
Definition: Constants.h:83
static const fltSemantics & IEEEhalf() LLVM_READNONE
Definition: APFloat.cpp:152
SelectPatternFlavor Flavor
Align max(MaybeAlign Lhs, Align Rhs)
Definition: Alignment.h:390
static Instruction * shrinkInsertElt(CastInst &Trunc, InstCombiner::BuilderTy &Builder)
Try to narrow the width of an insert element.
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type...
Definition: Type.cpp:134
This struct is a compact representation of a valid (power of two) or undefined (0) alignment...
Definition: Alignment.h:117
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
Instruction * user_back()
Specialize the methods defined in Value, as we know that an instruction can only be used by other ins...
Definition: Instruction.h:63
Value * CreateInsertElement(Value *Vec, Value *NewElt, Value *Idx, const Twine &Name="")
Definition: IRBuilder.h:2322
static Instruction * shrinkSplatShuffle(TruncInst &Trunc, InstCombiner::BuilderTy &Builder)
Try to narrow the width of a splat shuffle.
Instruction * visitSExt(SExtInst &CI)
signed less than
Definition: InstrTypes.h:761
This class represents a cast from floating point to unsigned integer.
uint64_t getPointerDereferenceableBytes(const DataLayout &DL, bool &CanBeNull) const
Returns the number of bytes known to be dereferenceable for the pointer value.
Definition: Value.cpp:608
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:374
Instruction * visitZExt(ZExtInst &CI)
ConstantInt * getInt32(uint32_t C)
Get a constant 32-bit value.
Definition: IRBuilder.h:343
static CastInst * CreateFPCast(Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Create an FPExt, BitCast, or FPTrunc for fp -> fp casts.
static unsigned isEliminableCastPair(Instruction::CastOps firstOpcode, Instruction::CastOps secondOpcode, Type *SrcTy, Type *MidTy, Type *DstTy, Type *SrcIntPtrTy, Type *MidIntPtrTy, Type *DstIntPtrTy)
Determine how a pair of casts can be eliminated, if they can be at all.
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 PHINode * Create(Type *Ty, unsigned NumReservedValues, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Constructors - NumReservedValues is a hint for the number of incoming edges that this phi node will h...
Type * getDestTy() const
Return the destination type, as a convenience.
Definition: InstrTypes.h:699
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 setAlignment(MaybeAlign Align)
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
BinaryOp_match< cst_pred_ty< is_zero_int >, ValTy, Instruction::Sub > m_Neg(const ValTy &V)
Matches a &#39;Neg&#39; as &#39;sub 0, V&#39;.
unsigned getVectorNumElements() const
Definition: DerivedTypes.h:566
Class to represent vector types.
Definition: DerivedTypes.h:432
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:55
Class for arbitrary precision integers.
Definition: APInt.h:69
bool isPowerOf2() const
Check if this APInt&#39;s value is a power of two greater than zero.
Definition: APInt.h:463
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.
iterator_range< user_iterator > users()
Definition: Value.h:420
bool hasNoSignedWrap() const
Test whether this operation is known to never undergo signed overflow, aka the nsw property...
Definition: Operator.h:95
const Value * getFalseValue() const
static BinaryOperator * CreateFDivFMF(Value *V1, Value *V2, Instruction *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:273
static BinaryOperator * CreateFNegFMF(Value *Op, Instruction *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:283
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 ...
Predicate getPredicate() const
Return the predicate for this instruction.
Definition: InstrTypes.h:807
Instruction * visitTrunc(TruncInst &CI)
static Type * shrinkFPConstantVector(Value *V)
FNeg_match< OpTy > m_FNeg(const OpTy &X)
Match &#39;fneg X&#39; as &#39;fsub -0.0, X&#39;.
Definition: PatternMatch.h:814
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:180
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:55
Instruction * visitSIToFP(CastInst &CI)
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
static VectorType * get(Type *ElementType, ElementCount EC)
This static method is the primary way to construct an VectorType.
Definition: Type.cpp:614
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
BasicBlock * getIncomingBlock(unsigned i) const
Return incoming basic block number i.
#define I(x, y, z)
Definition: MD5.cpp:58
static Instruction * foldVecTruncToExtElt(TruncInst &Trunc, InstCombiner &IC)
Given a vector that is bitcast to an integer, optionally logically right-shifted, and truncated...
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
This instruction extracts a single (scalar) element from a VectorType value.
Value * CreateCast(Instruction::CastOps Op, Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:2000
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This class represents a truncation of floating point types.
LLVM Value Representation.
Definition: Value.h:74
This file provides internal interfaces used to implement the InstCombine.
SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, Instruction::CastOps *CastOp=nullptr, unsigned Depth=0)
Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind and providing the out param...
static bool canEvaluateSExtd(Value *V, Type *Ty)
Return true if we can take the specified value and return it as type Ty without inserting any new cas...
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
Instruction * commonPointerCastTransforms(CastInst &CI)
Implement the transforms for cast of pointer (bitcast/ptrtoint)
Type * getElementType() const
Definition: DerivedTypes.h:399
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:433
static bool canAlwaysEvaluateInType(Value *V, Type *Ty)
Constants and extensions/truncates from the destination type are always free to be evaluated in that ...
bool isNonNegative() const
Returns true if this value is known to be non-negative.
Definition: KnownBits.h:98
unsigned countLeadingZeros() const
The APInt version of the countLeadingZeros functions in MathExtras.h.
Definition: APInt.h:1604
bool isBigEndian() const
Definition: DataLayout.h:233
static Constant * get(LLVMContext &Context, ArrayRef< uint8_t > Elts)
get() constructors - Return a constant with vector type with an element count and element type matchi...
Definition: Constants.cpp:2595
Instruction * visitPtrToInt(PtrToIntInst &CI)
static ExtractElementInst * Create(Value *Vec, Value *Idx, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
#define LLVM_DEBUG(X)
Definition: Debug.h:122
op_range incoming_values()
This class represents an extension of floating point types.
bool isDoubleTy() const
Return true if this is &#39;double&#39;, a 64-bit IEEE fp type.
Definition: Type.h:150
Type * getElementType() const
Definition: DerivedTypes.h:598
static UnaryOperator * CreateFNegFMF(Value *Op, Instruction *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:166
bool isNullValue() const
Determine if all bits are clear.
Definition: APInt.h:405
an instruction to allocate memory on the stack
Definition: Instructions.h:59
Instruction * visitFPTrunc(FPTruncInst &CI)
bool hasNoUnsignedWrap() const
Test whether this operation is known to never undergo unsigned overflow, aka the nuw property...
Definition: Operator.h:89