LLVM  8.0.0svn
InstCombineCasts.cpp
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1 //===- InstCombineCasts.cpp -----------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the visit functions for cast operations.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "InstCombineInternal.h"
15 #include "llvm/ADT/SetVector.h"
18 #include "llvm/IR/DataLayout.h"
19 #include "llvm/IR/DIBuilder.h"
20 #include "llvm/IR/PatternMatch.h"
21 #include "llvm/Support/KnownBits.h"
22 using namespace llvm;
23 using namespace PatternMatch;
24 
25 #define DEBUG_TYPE "instcombine"
26 
27 /// Analyze 'Val', seeing if it is a simple linear expression.
28 /// If so, decompose it, returning some value X, such that Val is
29 /// X*Scale+Offset.
30 ///
31 static Value *decomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
32  uint64_t &Offset) {
33  if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
34  Offset = CI->getZExtValue();
35  Scale = 0;
36  return ConstantInt::get(Val->getType(), 0);
37  }
38 
39  if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
40  // Cannot look past anything that might overflow.
42  if (OBI && !OBI->hasNoUnsignedWrap() && !OBI->hasNoSignedWrap()) {
43  Scale = 1;
44  Offset = 0;
45  return Val;
46  }
47 
48  if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
49  if (I->getOpcode() == Instruction::Shl) {
50  // This is a value scaled by '1 << the shift amt'.
51  Scale = UINT64_C(1) << RHS->getZExtValue();
52  Offset = 0;
53  return I->getOperand(0);
54  }
55 
56  if (I->getOpcode() == Instruction::Mul) {
57  // This value is scaled by 'RHS'.
58  Scale = RHS->getZExtValue();
59  Offset = 0;
60  return I->getOperand(0);
61  }
62 
63  if (I->getOpcode() == Instruction::Add) {
64  // We have X+C. Check to see if we really have (X*C2)+C1,
65  // where C1 is divisible by C2.
66  unsigned SubScale;
67  Value *SubVal =
68  decomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
69  Offset += RHS->getZExtValue();
70  Scale = SubScale;
71  return SubVal;
72  }
73  }
74  }
75 
76  // Otherwise, we can't look past this.
77  Scale = 1;
78  Offset = 0;
79  return Val;
80 }
81 
82 /// If we find a cast of an allocation instruction, try to eliminate the cast by
83 /// moving the type information into the alloc.
84 Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
85  AllocaInst &AI) {
86  PointerType *PTy = cast<PointerType>(CI.getType());
87 
88  BuilderTy AllocaBuilder(Builder);
89  AllocaBuilder.SetInsertPoint(&AI);
90 
91  // Get the type really allocated and the type casted to.
92  Type *AllocElTy = AI.getAllocatedType();
93  Type *CastElTy = PTy->getElementType();
94  if (!AllocElTy->isSized() || !CastElTy->isSized()) return nullptr;
95 
96  unsigned AllocElTyAlign = DL.getABITypeAlignment(AllocElTy);
97  unsigned CastElTyAlign = DL.getABITypeAlignment(CastElTy);
98  if (CastElTyAlign < AllocElTyAlign) return nullptr;
99 
100  // If the allocation has multiple uses, only promote it if we are strictly
101  // increasing the alignment of the resultant allocation. If we keep it the
102  // same, we open the door to infinite loops of various kinds.
103  if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return nullptr;
104 
105  uint64_t AllocElTySize = DL.getTypeAllocSize(AllocElTy);
106  uint64_t CastElTySize = DL.getTypeAllocSize(CastElTy);
107  if (CastElTySize == 0 || AllocElTySize == 0) return nullptr;
108 
109  // If the allocation has multiple uses, only promote it if we're not
110  // shrinking the amount of memory being allocated.
111  uint64_t AllocElTyStoreSize = DL.getTypeStoreSize(AllocElTy);
112  uint64_t CastElTyStoreSize = DL.getTypeStoreSize(CastElTy);
113  if (!AI.hasOneUse() && CastElTyStoreSize < AllocElTyStoreSize) return nullptr;
114 
115  // See if we can satisfy the modulus by pulling a scale out of the array
116  // size argument.
117  unsigned ArraySizeScale;
118  uint64_t ArrayOffset;
119  Value *NumElements = // See if the array size is a decomposable linear expr.
120  decomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
121 
122  // If we can now satisfy the modulus, by using a non-1 scale, we really can
123  // do the xform.
124  if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
125  (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return nullptr;
126 
127  unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
128  Value *Amt = nullptr;
129  if (Scale == 1) {
130  Amt = NumElements;
131  } else {
132  Amt = ConstantInt::get(AI.getArraySize()->getType(), Scale);
133  // Insert before the alloca, not before the cast.
134  Amt = AllocaBuilder.CreateMul(Amt, NumElements);
135  }
136 
137  if (uint64_t Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
139  Offset, true);
140  Amt = AllocaBuilder.CreateAdd(Amt, Off);
141  }
142 
143  AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
144  New->setAlignment(AI.getAlignment());
145  New->takeName(&AI);
147 
148  // If the allocation has multiple real uses, insert a cast and change all
149  // things that used it to use the new cast. This will also hack on CI, but it
150  // will die soon.
151  if (!AI.hasOneUse()) {
152  // New is the allocation instruction, pointer typed. AI is the original
153  // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
154  Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
155  replaceInstUsesWith(AI, NewCast);
156  }
157  return replaceInstUsesWith(CI, New);
158 }
159 
160 /// Given an expression that CanEvaluateTruncated or CanEvaluateSExtd returns
161 /// true for, actually insert the code to evaluate the expression.
162 Value *InstCombiner::EvaluateInDifferentType(Value *V, Type *Ty,
163  bool isSigned) {
164  if (Constant *C = dyn_cast<Constant>(V)) {
165  C = ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
166  // If we got a constantexpr back, try to simplify it with DL info.
167  if (Constant *FoldedC = ConstantFoldConstant(C, DL, &TLI))
168  C = FoldedC;
169  return C;
170  }
171 
172  // Otherwise, it must be an instruction.
173  Instruction *I = cast<Instruction>(V);
174  Instruction *Res = nullptr;
175  unsigned Opc = I->getOpcode();
176  switch (Opc) {
177  case Instruction::Add:
178  case Instruction::Sub:
179  case Instruction::Mul:
180  case Instruction::And:
181  case Instruction::Or:
182  case Instruction::Xor:
183  case Instruction::AShr:
184  case Instruction::LShr:
185  case Instruction::Shl:
186  case Instruction::UDiv:
187  case Instruction::URem: {
188  Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
189  Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
190  Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
191  break;
192  }
193  case Instruction::Trunc:
194  case Instruction::ZExt:
195  case Instruction::SExt:
196  // If the source type of the cast is the type we're trying for then we can
197  // just return the source. There's no need to insert it because it is not
198  // new.
199  if (I->getOperand(0)->getType() == Ty)
200  return I->getOperand(0);
201 
202  // Otherwise, must be the same type of cast, so just reinsert a new one.
203  // This also handles the case of zext(trunc(x)) -> zext(x).
204  Res = CastInst::CreateIntegerCast(I->getOperand(0), Ty,
205  Opc == Instruction::SExt);
206  break;
207  case Instruction::Select: {
208  Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
209  Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
210  Res = SelectInst::Create(I->getOperand(0), True, False);
211  break;
212  }
213  case Instruction::PHI: {
214  PHINode *OPN = cast<PHINode>(I);
215  PHINode *NPN = PHINode::Create(Ty, OPN->getNumIncomingValues());
216  for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
217  Value *V =
218  EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
219  NPN->addIncoming(V, OPN->getIncomingBlock(i));
220  }
221  Res = NPN;
222  break;
223  }
224  default:
225  // TODO: Can handle more cases here.
226  llvm_unreachable("Unreachable!");
227  }
228 
229  Res->takeName(I);
230  return InsertNewInstWith(Res, *I);
231 }
232 
233 Instruction::CastOps InstCombiner::isEliminableCastPair(const CastInst *CI1,
234  const CastInst *CI2) {
235  Type *SrcTy = CI1->getSrcTy();
236  Type *MidTy = CI1->getDestTy();
237  Type *DstTy = CI2->getDestTy();
238 
239  Instruction::CastOps firstOp = CI1->getOpcode();
240  Instruction::CastOps secondOp = CI2->getOpcode();
241  Type *SrcIntPtrTy =
242  SrcTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(SrcTy) : nullptr;
243  Type *MidIntPtrTy =
244  MidTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(MidTy) : nullptr;
245  Type *DstIntPtrTy =
246  DstTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(DstTy) : nullptr;
247  unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
248  DstTy, SrcIntPtrTy, MidIntPtrTy,
249  DstIntPtrTy);
250 
251  // We don't want to form an inttoptr or ptrtoint that converts to an integer
252  // type that differs from the pointer size.
253  if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
254  (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
255  Res = 0;
256 
257  return Instruction::CastOps(Res);
258 }
259 
260 /// Implement the transforms common to all CastInst visitors.
262  Value *Src = CI.getOperand(0);
263 
264  // Try to eliminate a cast of a cast.
265  if (auto *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
266  if (Instruction::CastOps NewOpc = isEliminableCastPair(CSrc, &CI)) {
267  // The first cast (CSrc) is eliminable so we need to fix up or replace
268  // the second cast (CI). CSrc will then have a good chance of being dead.
269  auto *Ty = CI.getType();
270  auto *Res = CastInst::Create(NewOpc, CSrc->getOperand(0), Ty);
271  // Point debug users of the dying cast to the new one.
272  if (CSrc->hasOneUse())
273  replaceAllDbgUsesWith(*CSrc, *Res, CI, DT);
274  return Res;
275  }
276  }
277 
278  if (auto *Sel = dyn_cast<SelectInst>(Src)) {
279  // We are casting a select. Try to fold the cast into the select, but only
280  // if the select does not have a compare instruction with matching operand
281  // types. Creating a select with operands that are different sizes than its
282  // condition may inhibit other folds and lead to worse codegen.
283  auto *Cmp = dyn_cast<CmpInst>(Sel->getCondition());
284  if (!Cmp || Cmp->getOperand(0)->getType() != Sel->getType())
285  if (Instruction *NV = FoldOpIntoSelect(CI, Sel)) {
286  replaceAllDbgUsesWith(*Sel, *NV, CI, DT);
287  return NV;
288  }
289  }
290 
291  // If we are casting a PHI, then fold the cast into the PHI.
292  if (auto *PN = dyn_cast<PHINode>(Src)) {
293  // Don't do this if it would create a PHI node with an illegal type from a
294  // legal type.
295  if (!Src->getType()->isIntegerTy() || !CI.getType()->isIntegerTy() ||
296  shouldChangeType(CI.getType(), Src->getType()))
297  if (Instruction *NV = foldOpIntoPhi(CI, PN))
298  return NV;
299  }
300 
301  return nullptr;
302 }
303 
304 /// Constants and extensions/truncates from the destination type are always
305 /// free to be evaluated in that type. This is a helper for canEvaluate*.
306 static bool canAlwaysEvaluateInType(Value *V, Type *Ty) {
307  if (isa<Constant>(V))
308  return true;
309  Value *X;
310  if ((match(V, m_ZExtOrSExt(m_Value(X))) || match(V, m_Trunc(m_Value(X)))) &&
311  X->getType() == Ty)
312  return true;
313 
314  return false;
315 }
316 
317 /// Filter out values that we can not evaluate in the destination type for free.
318 /// This is a helper for canEvaluate*.
319 static bool canNotEvaluateInType(Value *V, Type *Ty) {
320  assert(!isa<Constant>(V) && "Constant should already be handled.");
321  if (!isa<Instruction>(V))
322  return true;
323  // We don't extend or shrink something that has multiple uses -- doing so
324  // would require duplicating the instruction which isn't profitable.
325  if (!V->hasOneUse())
326  return true;
327 
328  return false;
329 }
330 
331 /// Return true if we can evaluate the specified expression tree as type Ty
332 /// instead of its larger type, and arrive with the same value.
333 /// This is used by code that tries to eliminate truncates.
334 ///
335 /// Ty will always be a type smaller than V. We should return true if trunc(V)
336 /// can be computed by computing V in the smaller type. If V is an instruction,
337 /// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
338 /// makes sense if x and y can be efficiently truncated.
339 ///
340 /// This function works on both vectors and scalars.
341 ///
342 static bool canEvaluateTruncated(Value *V, Type *Ty, InstCombiner &IC,
343  Instruction *CxtI) {
344  if (canAlwaysEvaluateInType(V, Ty))
345  return true;
346  if (canNotEvaluateInType(V, Ty))
347  return false;
348 
349  auto *I = cast<Instruction>(V);
350  Type *OrigTy = V->getType();
351  switch (I->getOpcode()) {
352  case Instruction::Add:
353  case Instruction::Sub:
354  case Instruction::Mul:
355  case Instruction::And:
356  case Instruction::Or:
357  case Instruction::Xor:
358  // These operators can all arbitrarily be extended or truncated.
359  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
360  canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
361 
362  case Instruction::UDiv:
363  case Instruction::URem: {
364  // UDiv and URem can be truncated if all the truncated bits are zero.
365  uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
366  uint32_t BitWidth = Ty->getScalarSizeInBits();
367  assert(BitWidth < OrigBitWidth && "Unexpected bitwidths!");
368  APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
369  if (IC.MaskedValueIsZero(I->getOperand(0), Mask, 0, CxtI) &&
370  IC.MaskedValueIsZero(I->getOperand(1), Mask, 0, CxtI)) {
371  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
372  canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
373  }
374  break;
375  }
376  case Instruction::Shl: {
377  // If we are truncating the result of this SHL, and if it's a shift of a
378  // constant amount, we can always perform a SHL in a smaller type.
379  const APInt *Amt;
380  if (match(I->getOperand(1), m_APInt(Amt))) {
381  uint32_t BitWidth = Ty->getScalarSizeInBits();
382  if (Amt->getLimitedValue(BitWidth) < BitWidth)
383  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
384  }
385  break;
386  }
387  case Instruction::LShr: {
388  // If this is a truncate of a logical shr, we can truncate it to a smaller
389  // lshr iff we know that the bits we would otherwise be shifting in are
390  // already zeros.
391  const APInt *Amt;
392  if (match(I->getOperand(1), m_APInt(Amt))) {
393  uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
394  uint32_t BitWidth = Ty->getScalarSizeInBits();
395  if (Amt->getLimitedValue(BitWidth) < BitWidth &&
396  IC.MaskedValueIsZero(I->getOperand(0),
397  APInt::getBitsSetFrom(OrigBitWidth, BitWidth), 0, CxtI)) {
398  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
399  }
400  }
401  break;
402  }
403  case Instruction::AShr: {
404  // If this is a truncate of an arithmetic shr, we can truncate it to a
405  // smaller ashr iff we know that all the bits from the sign bit of the
406  // original type and the sign bit of the truncate type are similar.
407  // TODO: It is enough to check that the bits we would be shifting in are
408  // similar to sign bit of the truncate type.
409  const APInt *Amt;
410  if (match(I->getOperand(1), m_APInt(Amt))) {
411  uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
412  uint32_t BitWidth = Ty->getScalarSizeInBits();
413  if (Amt->getLimitedValue(BitWidth) < BitWidth &&
414  OrigBitWidth - BitWidth <
415  IC.ComputeNumSignBits(I->getOperand(0), 0, CxtI))
416  return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
417  }
418  break;
419  }
420  case Instruction::Trunc:
421  // trunc(trunc(x)) -> trunc(x)
422  return true;
423  case Instruction::ZExt:
424  case Instruction::SExt:
425  // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
426  // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
427  return true;
428  case Instruction::Select: {
429  SelectInst *SI = cast<SelectInst>(I);
430  return canEvaluateTruncated(SI->getTrueValue(), Ty, IC, CxtI) &&
431  canEvaluateTruncated(SI->getFalseValue(), Ty, IC, CxtI);
432  }
433  case Instruction::PHI: {
434  // We can change a phi if we can change all operands. Note that we never
435  // get into trouble with cyclic PHIs here because we only consider
436  // instructions with a single use.
437  PHINode *PN = cast<PHINode>(I);
438  for (Value *IncValue : PN->incoming_values())
439  if (!canEvaluateTruncated(IncValue, Ty, IC, CxtI))
440  return false;
441  return true;
442  }
443  default:
444  // TODO: Can handle more cases here.
445  break;
446  }
447 
448  return false;
449 }
450 
451 /// Given a vector that is bitcast to an integer, optionally logically
452 /// right-shifted, and truncated, convert it to an extractelement.
453 /// Example (big endian):
454 /// trunc (lshr (bitcast <4 x i32> %X to i128), 32) to i32
455 /// --->
456 /// extractelement <4 x i32> %X, 1
458  Value *TruncOp = Trunc.getOperand(0);
459  Type *DestType = Trunc.getType();
460  if (!TruncOp->hasOneUse() || !isa<IntegerType>(DestType))
461  return nullptr;
462 
463  Value *VecInput = nullptr;
464  ConstantInt *ShiftVal = nullptr;
465  if (!match(TruncOp, m_CombineOr(m_BitCast(m_Value(VecInput)),
466  m_LShr(m_BitCast(m_Value(VecInput)),
467  m_ConstantInt(ShiftVal)))) ||
468  !isa<VectorType>(VecInput->getType()))
469  return nullptr;
470 
471  VectorType *VecType = cast<VectorType>(VecInput->getType());
472  unsigned VecWidth = VecType->getPrimitiveSizeInBits();
473  unsigned DestWidth = DestType->getPrimitiveSizeInBits();
474  unsigned ShiftAmount = ShiftVal ? ShiftVal->getZExtValue() : 0;
475 
476  if ((VecWidth % DestWidth != 0) || (ShiftAmount % DestWidth != 0))
477  return nullptr;
478 
479  // If the element type of the vector doesn't match the result type,
480  // bitcast it to a vector type that we can extract from.
481  unsigned NumVecElts = VecWidth / DestWidth;
482  if (VecType->getElementType() != DestType) {
483  VecType = VectorType::get(DestType, NumVecElts);
484  VecInput = IC.Builder.CreateBitCast(VecInput, VecType, "bc");
485  }
486 
487  unsigned Elt = ShiftAmount / DestWidth;
488  if (IC.getDataLayout().isBigEndian())
489  Elt = NumVecElts - 1 - Elt;
490 
491  return ExtractElementInst::Create(VecInput, IC.Builder.getInt32(Elt));
492 }
493 
494 /// Rotate left/right may occur in a wider type than necessary because of type
495 /// promotion rules. Try to narrow all of the component instructions.
496 Instruction *InstCombiner::narrowRotate(TruncInst &Trunc) {
497  assert((isa<VectorType>(Trunc.getSrcTy()) ||
498  shouldChangeType(Trunc.getSrcTy(), Trunc.getType())) &&
499  "Don't narrow to an illegal scalar type");
500 
501  // First, find an or'd pair of opposite shifts with the same shifted operand:
502  // trunc (or (lshr ShVal, ShAmt0), (shl ShVal, ShAmt1))
503  Value *Or0, *Or1;
504  if (!match(Trunc.getOperand(0), m_OneUse(m_Or(m_Value(Or0), m_Value(Or1)))))
505  return nullptr;
506 
507  Value *ShVal, *ShAmt0, *ShAmt1;
508  if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal), m_Value(ShAmt0)))) ||
509  !match(Or1, m_OneUse(m_LogicalShift(m_Specific(ShVal), m_Value(ShAmt1)))))
510  return nullptr;
511 
512  auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode();
513  auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode();
514  if (ShiftOpcode0 == ShiftOpcode1)
515  return nullptr;
516 
517  // The shift amounts must add up to the narrow bit width.
518  Value *ShAmt;
519  bool SubIsOnLHS;
520  Type *DestTy = Trunc.getType();
521  unsigned NarrowWidth = DestTy->getScalarSizeInBits();
522  if (match(ShAmt0,
523  m_OneUse(m_Sub(m_SpecificInt(NarrowWidth), m_Specific(ShAmt1))))) {
524  ShAmt = ShAmt1;
525  SubIsOnLHS = true;
526  } else if (match(ShAmt1, m_OneUse(m_Sub(m_SpecificInt(NarrowWidth),
527  m_Specific(ShAmt0))))) {
528  ShAmt = ShAmt0;
529  SubIsOnLHS = false;
530  } else {
531  return nullptr;
532  }
533 
534  // The shifted value must have high zeros in the wide type. Typically, this
535  // will be a zext, but it could also be the result of an 'and' or 'shift'.
536  unsigned WideWidth = Trunc.getSrcTy()->getScalarSizeInBits();
537  APInt HiBitMask = APInt::getHighBitsSet(WideWidth, WideWidth - NarrowWidth);
538  if (!MaskedValueIsZero(ShVal, HiBitMask, 0, &Trunc))
539  return nullptr;
540 
541  // We have an unnecessarily wide rotate!
542  // trunc (or (lshr ShVal, ShAmt), (shl ShVal, BitWidth - ShAmt))
543  // Narrow it down to eliminate the zext/trunc:
544  // or (lshr trunc(ShVal), ShAmt0'), (shl trunc(ShVal), ShAmt1')
545  Value *NarrowShAmt = Builder.CreateTrunc(ShAmt, DestTy);
546  Value *NegShAmt = Builder.CreateNeg(NarrowShAmt);
547 
548  // Mask both shift amounts to ensure there's no UB from oversized shifts.
549  Constant *MaskC = ConstantInt::get(DestTy, NarrowWidth - 1);
550  Value *MaskedShAmt = Builder.CreateAnd(NarrowShAmt, MaskC);
551  Value *MaskedNegShAmt = Builder.CreateAnd(NegShAmt, MaskC);
552 
553  // Truncate the original value and use narrow ops.
554  Value *X = Builder.CreateTrunc(ShVal, DestTy);
555  Value *NarrowShAmt0 = SubIsOnLHS ? MaskedNegShAmt : MaskedShAmt;
556  Value *NarrowShAmt1 = SubIsOnLHS ? MaskedShAmt : MaskedNegShAmt;
557  Value *NarrowSh0 = Builder.CreateBinOp(ShiftOpcode0, X, NarrowShAmt0);
558  Value *NarrowSh1 = Builder.CreateBinOp(ShiftOpcode1, X, NarrowShAmt1);
559  return BinaryOperator::CreateOr(NarrowSh0, NarrowSh1);
560 }
561 
562 /// Try to narrow the width of math or bitwise logic instructions by pulling a
563 /// truncate ahead of binary operators.
564 /// TODO: Transforms for truncated shifts should be moved into here.
565 Instruction *InstCombiner::narrowBinOp(TruncInst &Trunc) {
566  Type *SrcTy = Trunc.getSrcTy();
567  Type *DestTy = Trunc.getType();
568  if (!isa<VectorType>(SrcTy) && !shouldChangeType(SrcTy, DestTy))
569  return nullptr;
570 
571  BinaryOperator *BinOp;
572  if (!match(Trunc.getOperand(0), m_OneUse(m_BinOp(BinOp))))
573  return nullptr;
574 
575  Value *BinOp0 = BinOp->getOperand(0);
576  Value *BinOp1 = BinOp->getOperand(1);
577  switch (BinOp->getOpcode()) {
578  case Instruction::And:
579  case Instruction::Or:
580  case Instruction::Xor:
581  case Instruction::Add:
582  case Instruction::Sub:
583  case Instruction::Mul: {
584  Constant *C;
585  if (match(BinOp0, m_Constant(C))) {
586  // trunc (binop C, X) --> binop (trunc C', X)
587  Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
588  Value *TruncX = Builder.CreateTrunc(BinOp1, DestTy);
589  return BinaryOperator::Create(BinOp->getOpcode(), NarrowC, TruncX);
590  }
591  if (match(BinOp1, m_Constant(C))) {
592  // trunc (binop X, C) --> binop (trunc X, C')
593  Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
594  Value *TruncX = Builder.CreateTrunc(BinOp0, DestTy);
595  return BinaryOperator::Create(BinOp->getOpcode(), TruncX, NarrowC);
596  }
597  Value *X;
598  if (match(BinOp0, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) {
599  // trunc (binop (ext X), Y) --> binop X, (trunc Y)
600  Value *NarrowOp1 = Builder.CreateTrunc(BinOp1, DestTy);
601  return BinaryOperator::Create(BinOp->getOpcode(), X, NarrowOp1);
602  }
603  if (match(BinOp1, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) {
604  // trunc (binop Y, (ext X)) --> binop (trunc Y), X
605  Value *NarrowOp0 = Builder.CreateTrunc(BinOp0, DestTy);
606  return BinaryOperator::Create(BinOp->getOpcode(), NarrowOp0, X);
607  }
608  break;
609  }
610 
611  default: break;
612  }
613 
614  if (Instruction *NarrowOr = narrowRotate(Trunc))
615  return NarrowOr;
616 
617  return nullptr;
618 }
619 
620 /// Try to narrow the width of a splat shuffle. This could be generalized to any
621 /// shuffle with a constant operand, but we limit the transform to avoid
622 /// creating a shuffle type that targets may not be able to lower effectively.
624  InstCombiner::BuilderTy &Builder) {
625  auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
626  if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) &&
627  Shuf->getMask()->getSplatValue() &&
628  Shuf->getType() == Shuf->getOperand(0)->getType()) {
629  // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
630  Constant *NarrowUndef = UndefValue::get(Trunc.getType());
631  Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
632  return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getMask());
633  }
634 
635  return nullptr;
636 }
637 
638 /// Try to narrow the width of an insert element. This could be generalized for
639 /// any vector constant, but we limit the transform to insertion into undef to
640 /// avoid potential backend problems from unsupported insertion widths. This
641 /// could also be extended to handle the case of inserting a scalar constant
642 /// into a vector variable.
644  InstCombiner::BuilderTy &Builder) {
645  Instruction::CastOps Opcode = Trunc.getOpcode();
646  assert((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) &&
647  "Unexpected instruction for shrinking");
648 
649  auto *InsElt = dyn_cast<InsertElementInst>(Trunc.getOperand(0));
650  if (!InsElt || !InsElt->hasOneUse())
651  return nullptr;
652 
653  Type *DestTy = Trunc.getType();
654  Type *DestScalarTy = DestTy->getScalarType();
655  Value *VecOp = InsElt->getOperand(0);
656  Value *ScalarOp = InsElt->getOperand(1);
657  Value *Index = InsElt->getOperand(2);
658 
659  if (isa<UndefValue>(VecOp)) {
660  // trunc (inselt undef, X, Index) --> inselt undef, (trunc X), Index
661  // fptrunc (inselt undef, X, Index) --> inselt undef, (fptrunc X), Index
662  UndefValue *NarrowUndef = UndefValue::get(DestTy);
663  Value *NarrowOp = Builder.CreateCast(Opcode, ScalarOp, DestScalarTy);
664  return InsertElementInst::Create(NarrowUndef, NarrowOp, Index);
665  }
666 
667  return nullptr;
668 }
669 
671  if (Instruction *Result = commonCastTransforms(CI))
672  return Result;
673 
674  Value *Src = CI.getOperand(0);
675  Type *DestTy = CI.getType(), *SrcTy = Src->getType();
676 
677  // Attempt to truncate the entire input expression tree to the destination
678  // type. Only do this if the dest type is a simple type, don't convert the
679  // expression tree to something weird like i93 unless the source is also
680  // strange.
681  if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) &&
682  canEvaluateTruncated(Src, DestTy, *this, &CI)) {
683 
684  // If this cast is a truncate, evaluting in a different type always
685  // eliminates the cast, so it is always a win.
686  LLVM_DEBUG(
687  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
688  " to avoid cast: "
689  << CI << '\n');
690  Value *Res = EvaluateInDifferentType(Src, DestTy, false);
691  assert(Res->getType() == DestTy);
692  return replaceInstUsesWith(CI, Res);
693  }
694 
695  // Test if the trunc is the user of a select which is part of a
696  // minimum or maximum operation. If so, don't do any more simplification.
697  // Even simplifying demanded bits can break the canonical form of a
698  // min/max.
699  Value *LHS, *RHS;
700  if (SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0)))
701  if (matchSelectPattern(SI, LHS, RHS).Flavor != SPF_UNKNOWN)
702  return nullptr;
703 
704  // See if we can simplify any instructions used by the input whose sole
705  // purpose is to compute bits we don't care about.
706  if (SimplifyDemandedInstructionBits(CI))
707  return &CI;
708 
709  if (DestTy->getScalarSizeInBits() == 1) {
710  Value *Zero = Constant::getNullValue(Src->getType());
711  if (DestTy->isIntegerTy()) {
712  // Canonicalize trunc x to i1 -> icmp ne (and x, 1), 0 (scalar only).
713  // TODO: We canonicalize to more instructions here because we are probably
714  // lacking equivalent analysis for trunc relative to icmp. There may also
715  // be codegen concerns. If those trunc limitations were removed, we could
716  // remove this transform.
717  Value *And = Builder.CreateAnd(Src, ConstantInt::get(SrcTy, 1));
718  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
719  }
720 
721  // For vectors, we do not canonicalize all truncs to icmp, so optimize
722  // patterns that would be covered within visitICmpInst.
723  Value *X;
724  const APInt *C;
725  if (match(Src, m_OneUse(m_LShr(m_Value(X), m_APInt(C))))) {
726  // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0
727  APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C);
728  Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC));
729  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
730  }
731  if (match(Src, m_OneUse(m_c_Or(m_LShr(m_Value(X), m_APInt(C)),
732  m_Deferred(X))))) {
733  // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0
734  APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C) | 1;
735  Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC));
736  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
737  }
738  }
739 
740  // FIXME: Maybe combine the next two transforms to handle the no cast case
741  // more efficiently. Support vector types. Cleanup code by using m_OneUse.
742 
743  // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
744  Value *A = nullptr; ConstantInt *Cst = nullptr;
745  if (Src->hasOneUse() &&
746  match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
747  // We have three types to worry about here, the type of A, the source of
748  // the truncate (MidSize), and the destination of the truncate. We know that
749  // ASize < MidSize and MidSize > ResultSize, but don't know the relation
750  // between ASize and ResultSize.
751  unsigned ASize = A->getType()->getPrimitiveSizeInBits();
752 
753  // If the shift amount is larger than the size of A, then the result is
754  // known to be zero because all the input bits got shifted out.
755  if (Cst->getZExtValue() >= ASize)
756  return replaceInstUsesWith(CI, Constant::getNullValue(DestTy));
757 
758  // Since we're doing an lshr and a zero extend, and know that the shift
759  // amount is smaller than ASize, it is always safe to do the shift in A's
760  // type, then zero extend or truncate to the result.
761  Value *Shift = Builder.CreateLShr(A, Cst->getZExtValue());
762  Shift->takeName(Src);
763  return CastInst::CreateIntegerCast(Shift, DestTy, false);
764  }
765 
766  // FIXME: We should canonicalize to zext/trunc and remove this transform.
767  // Transform trunc(lshr (sext A), Cst) to ashr A, Cst to eliminate type
768  // conversion.
769  // It works because bits coming from sign extension have the same value as
770  // the sign bit of the original value; performing ashr instead of lshr
771  // generates bits of the same value as the sign bit.
772  if (Src->hasOneUse() &&
773  match(Src, m_LShr(m_SExt(m_Value(A)), m_ConstantInt(Cst)))) {
774  Value *SExt = cast<Instruction>(Src)->getOperand(0);
775  const unsigned SExtSize = SExt->getType()->getPrimitiveSizeInBits();
776  const unsigned ASize = A->getType()->getPrimitiveSizeInBits();
777  const unsigned CISize = CI.getType()->getPrimitiveSizeInBits();
778  const unsigned MaxAmt = SExtSize - std::max(CISize, ASize);
779  unsigned ShiftAmt = Cst->getZExtValue();
780 
781  // This optimization can be only performed when zero bits generated by
782  // the original lshr aren't pulled into the value after truncation, so we
783  // can only shift by values no larger than the number of extension bits.
784  // FIXME: Instead of bailing when the shift is too large, use and to clear
785  // the extra bits.
786  if (ShiftAmt <= MaxAmt) {
787  if (CISize == ASize)
788  return BinaryOperator::CreateAShr(A, ConstantInt::get(CI.getType(),
789  std::min(ShiftAmt, ASize - 1)));
790  if (SExt->hasOneUse()) {
791  Value *Shift = Builder.CreateAShr(A, std::min(ShiftAmt, ASize - 1));
792  Shift->takeName(Src);
793  return CastInst::CreateIntegerCast(Shift, CI.getType(), true);
794  }
795  }
796  }
797 
798  if (Instruction *I = narrowBinOp(CI))
799  return I;
800 
801  if (Instruction *I = shrinkSplatShuffle(CI, Builder))
802  return I;
803 
804  if (Instruction *I = shrinkInsertElt(CI, Builder))
805  return I;
806 
807  if (Src->hasOneUse() && isa<IntegerType>(SrcTy) &&
808  shouldChangeType(SrcTy, DestTy)) {
809  // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
810  // dest type is native and cst < dest size.
811  if (match(Src, m_Shl(m_Value(A), m_ConstantInt(Cst))) &&
812  !match(A, m_Shr(m_Value(), m_Constant()))) {
813  // Skip shifts of shift by constants. It undoes a combine in
814  // FoldShiftByConstant and is the extend in reg pattern.
815  const unsigned DestSize = DestTy->getScalarSizeInBits();
816  if (Cst->getValue().ult(DestSize)) {
817  Value *NewTrunc = Builder.CreateTrunc(A, DestTy, A->getName() + ".tr");
818 
819  return BinaryOperator::Create(
820  Instruction::Shl, NewTrunc,
821  ConstantInt::get(DestTy, Cst->getValue().trunc(DestSize)));
822  }
823  }
824  }
825 
826  if (Instruction *I = foldVecTruncToExtElt(CI, *this))
827  return I;
828 
829  return nullptr;
830 }
831 
832 Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, ZExtInst &CI,
833  bool DoTransform) {
834  // If we are just checking for a icmp eq of a single bit and zext'ing it
835  // to an integer, then shift the bit to the appropriate place and then
836  // cast to integer to avoid the comparison.
837  const APInt *Op1CV;
838  if (match(ICI->getOperand(1), m_APInt(Op1CV))) {
839 
840  // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
841  // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
842  if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isNullValue()) ||
843  (ICI->getPredicate() == ICmpInst::ICMP_SGT && Op1CV->isAllOnesValue())) {
844  if (!DoTransform) return ICI;
845 
846  Value *In = ICI->getOperand(0);
847  Value *Sh = ConstantInt::get(In->getType(),
848  In->getType()->getScalarSizeInBits() - 1);
849  In = Builder.CreateLShr(In, Sh, In->getName() + ".lobit");
850  if (In->getType() != CI.getType())
851  In = Builder.CreateIntCast(In, CI.getType(), false /*ZExt*/);
852 
853  if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
854  Constant *One = ConstantInt::get(In->getType(), 1);
855  In = Builder.CreateXor(In, One, In->getName() + ".not");
856  }
857 
858  return replaceInstUsesWith(CI, In);
859  }
860 
861  // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
862  // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
863  // zext (X == 1) to i32 --> X iff X has only the low bit set.
864  // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
865  // zext (X != 0) to i32 --> X iff X has only the low bit set.
866  // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
867  // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
868  // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
869  if ((Op1CV->isNullValue() || Op1CV->isPowerOf2()) &&
870  // This only works for EQ and NE
871  ICI->isEquality()) {
872  // If Op1C some other power of two, convert:
873  KnownBits Known = computeKnownBits(ICI->getOperand(0), 0, &CI);
874 
875  APInt KnownZeroMask(~Known.Zero);
876  if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
877  if (!DoTransform) return ICI;
878 
879  bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
880  if (!Op1CV->isNullValue() && (*Op1CV != KnownZeroMask)) {
881  // (X&4) == 2 --> false
882  // (X&4) != 2 --> true
883  Constant *Res = ConstantInt::get(CI.getType(), isNE);
884  return replaceInstUsesWith(CI, Res);
885  }
886 
887  uint32_t ShAmt = KnownZeroMask.logBase2();
888  Value *In = ICI->getOperand(0);
889  if (ShAmt) {
890  // Perform a logical shr by shiftamt.
891  // Insert the shift to put the result in the low bit.
892  In = Builder.CreateLShr(In, ConstantInt::get(In->getType(), ShAmt),
893  In->getName() + ".lobit");
894  }
895 
896  if (!Op1CV->isNullValue() == isNE) { // Toggle the low bit.
897  Constant *One = ConstantInt::get(In->getType(), 1);
898  In = Builder.CreateXor(In, One);
899  }
900 
901  if (CI.getType() == In->getType())
902  return replaceInstUsesWith(CI, In);
903 
904  Value *IntCast = Builder.CreateIntCast(In, CI.getType(), false);
905  return replaceInstUsesWith(CI, IntCast);
906  }
907  }
908  }
909 
910  // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
911  // It is also profitable to transform icmp eq into not(xor(A, B)) because that
912  // may lead to additional simplifications.
913  if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
914  if (IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
915  Value *LHS = ICI->getOperand(0);
916  Value *RHS = ICI->getOperand(1);
917 
918  KnownBits KnownLHS = computeKnownBits(LHS, 0, &CI);
919  KnownBits KnownRHS = computeKnownBits(RHS, 0, &CI);
920 
921  if (KnownLHS.Zero == KnownRHS.Zero && KnownLHS.One == KnownRHS.One) {
922  APInt KnownBits = KnownLHS.Zero | KnownLHS.One;
923  APInt UnknownBit = ~KnownBits;
924  if (UnknownBit.countPopulation() == 1) {
925  if (!DoTransform) return ICI;
926 
927  Value *Result = Builder.CreateXor(LHS, RHS);
928 
929  // Mask off any bits that are set and won't be shifted away.
930  if (KnownLHS.One.uge(UnknownBit))
931  Result = Builder.CreateAnd(Result,
932  ConstantInt::get(ITy, UnknownBit));
933 
934  // Shift the bit we're testing down to the lsb.
935  Result = Builder.CreateLShr(
936  Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
937 
938  if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
939  Result = Builder.CreateXor(Result, ConstantInt::get(ITy, 1));
940  Result->takeName(ICI);
941  return replaceInstUsesWith(CI, Result);
942  }
943  }
944  }
945  }
946 
947  return nullptr;
948 }
949 
950 /// Determine if the specified value can be computed in the specified wider type
951 /// and produce the same low bits. If not, return false.
952 ///
953 /// If this function returns true, it can also return a non-zero number of bits
954 /// (in BitsToClear) which indicates that the value it computes is correct for
955 /// the zero extend, but that the additional BitsToClear bits need to be zero'd
956 /// out. For example, to promote something like:
957 ///
958 /// %B = trunc i64 %A to i32
959 /// %C = lshr i32 %B, 8
960 /// %E = zext i32 %C to i64
961 ///
962 /// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
963 /// set to 8 to indicate that the promoted value needs to have bits 24-31
964 /// cleared in addition to bits 32-63. Since an 'and' will be generated to
965 /// clear the top bits anyway, doing this has no extra cost.
966 ///
967 /// This function works on both vectors and scalars.
968 static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear,
969  InstCombiner &IC, Instruction *CxtI) {
970  BitsToClear = 0;
971  if (canAlwaysEvaluateInType(V, Ty))
972  return true;
973  if (canNotEvaluateInType(V, Ty))
974  return false;
975 
976  auto *I = cast<Instruction>(V);
977  unsigned Tmp;
978  switch (I->getOpcode()) {
979  case Instruction::ZExt: // zext(zext(x)) -> zext(x).
980  case Instruction::SExt: // zext(sext(x)) -> sext(x).
981  case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
982  return true;
983  case Instruction::And:
984  case Instruction::Or:
985  case Instruction::Xor:
986  case Instruction::Add:
987  case Instruction::Sub:
988  case Instruction::Mul:
989  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI) ||
990  !canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI))
991  return false;
992  // These can all be promoted if neither operand has 'bits to clear'.
993  if (BitsToClear == 0 && Tmp == 0)
994  return true;
995 
996  // If the operation is an AND/OR/XOR and the bits to clear are zero in the
997  // other side, BitsToClear is ok.
998  if (Tmp == 0 && I->isBitwiseLogicOp()) {
999  // We use MaskedValueIsZero here for generality, but the case we care
1000  // about the most is constant RHS.
1001  unsigned VSize = V->getType()->getScalarSizeInBits();
1002  if (IC.MaskedValueIsZero(I->getOperand(1),
1003  APInt::getHighBitsSet(VSize, BitsToClear),
1004  0, CxtI)) {
1005  // If this is an And instruction and all of the BitsToClear are
1006  // known to be zero we can reset BitsToClear.
1007  if (I->getOpcode() == Instruction::And)
1008  BitsToClear = 0;
1009  return true;
1010  }
1011  }
1012 
1013  // Otherwise, we don't know how to analyze this BitsToClear case yet.
1014  return false;
1015 
1016  case Instruction::Shl: {
1017  // We can promote shl(x, cst) if we can promote x. Since shl overwrites the
1018  // upper bits we can reduce BitsToClear by the shift amount.
1019  const APInt *Amt;
1020  if (match(I->getOperand(1), m_APInt(Amt))) {
1021  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
1022  return false;
1023  uint64_t ShiftAmt = Amt->getZExtValue();
1024  BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
1025  return true;
1026  }
1027  return false;
1028  }
1029  case Instruction::LShr: {
1030  // We can promote lshr(x, cst) if we can promote x. This requires the
1031  // ultimate 'and' to clear out the high zero bits we're clearing out though.
1032  const APInt *Amt;
1033  if (match(I->getOperand(1), m_APInt(Amt))) {
1034  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
1035  return false;
1036  BitsToClear += Amt->getZExtValue();
1037  if (BitsToClear > V->getType()->getScalarSizeInBits())
1038  BitsToClear = V->getType()->getScalarSizeInBits();
1039  return true;
1040  }
1041  // Cannot promote variable LSHR.
1042  return false;
1043  }
1044  case Instruction::Select:
1045  if (!canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI) ||
1046  !canEvaluateZExtd(I->getOperand(2), Ty, BitsToClear, IC, CxtI) ||
1047  // TODO: If important, we could handle the case when the BitsToClear are
1048  // known zero in the disagreeing side.
1049  Tmp != BitsToClear)
1050  return false;
1051  return true;
1052 
1053  case Instruction::PHI: {
1054  // We can change a phi if we can change all operands. Note that we never
1055  // get into trouble with cyclic PHIs here because we only consider
1056  // instructions with a single use.
1057  PHINode *PN = cast<PHINode>(I);
1058  if (!canEvaluateZExtd(PN->getIncomingValue(0), Ty, BitsToClear, IC, CxtI))
1059  return false;
1060  for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
1061  if (!canEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp, IC, CxtI) ||
1062  // TODO: If important, we could handle the case when the BitsToClear
1063  // are known zero in the disagreeing input.
1064  Tmp != BitsToClear)
1065  return false;
1066  return true;
1067  }
1068  default:
1069  // TODO: Can handle more cases here.
1070  return false;
1071  }
1072 }
1073 
1075  // If this zero extend is only used by a truncate, let the truncate be
1076  // eliminated before we try to optimize this zext.
1077  if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
1078  return nullptr;
1079 
1080  // If one of the common conversion will work, do it.
1081  if (Instruction *Result = commonCastTransforms(CI))
1082  return Result;
1083 
1084  Value *Src = CI.getOperand(0);
1085  Type *SrcTy = Src->getType(), *DestTy = CI.getType();
1086 
1087  // Attempt to extend the entire input expression tree to the destination
1088  // type. Only do this if the dest type is a simple type, don't convert the
1089  // expression tree to something weird like i93 unless the source is also
1090  // strange.
1091  unsigned BitsToClear;
1092  if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) &&
1093  canEvaluateZExtd(Src, DestTy, BitsToClear, *this, &CI)) {
1094  assert(BitsToClear <= SrcTy->getScalarSizeInBits() &&
1095  "Can't clear more bits than in SrcTy");
1096 
1097  // Okay, we can transform this! Insert the new expression now.
1098  LLVM_DEBUG(
1099  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1100  " to avoid zero extend: "
1101  << CI << '\n');
1102  Value *Res = EvaluateInDifferentType(Src, DestTy, false);
1103  assert(Res->getType() == DestTy);
1104 
1105  // Preserve debug values referring to Src if the zext is its last use.
1106  if (auto *SrcOp = dyn_cast<Instruction>(Src))
1107  if (SrcOp->hasOneUse())
1108  replaceAllDbgUsesWith(*SrcOp, *Res, CI, DT);
1109 
1110  uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear;
1111  uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1112 
1113  // If the high bits are already filled with zeros, just replace this
1114  // cast with the result.
1115  if (MaskedValueIsZero(Res,
1116  APInt::getHighBitsSet(DestBitSize,
1117  DestBitSize-SrcBitsKept),
1118  0, &CI))
1119  return replaceInstUsesWith(CI, Res);
1120 
1121  // We need to emit an AND to clear the high bits.
1122  Constant *C = ConstantInt::get(Res->getType(),
1123  APInt::getLowBitsSet(DestBitSize, SrcBitsKept));
1124  return BinaryOperator::CreateAnd(Res, C);
1125  }
1126 
1127  // If this is a TRUNC followed by a ZEXT then we are dealing with integral
1128  // types and if the sizes are just right we can convert this into a logical
1129  // 'and' which will be much cheaper than the pair of casts.
1130  if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
1131  // TODO: Subsume this into EvaluateInDifferentType.
1132 
1133  // Get the sizes of the types involved. We know that the intermediate type
1134  // will be smaller than A or C, but don't know the relation between A and C.
1135  Value *A = CSrc->getOperand(0);
1136  unsigned SrcSize = A->getType()->getScalarSizeInBits();
1137  unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
1138  unsigned DstSize = CI.getType()->getScalarSizeInBits();
1139  // If we're actually extending zero bits, then if
1140  // SrcSize < DstSize: zext(a & mask)
1141  // SrcSize == DstSize: a & mask
1142  // SrcSize > DstSize: trunc(a) & mask
1143  if (SrcSize < DstSize) {
1144  APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
1145  Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
1146  Value *And = Builder.CreateAnd(A, AndConst, CSrc->getName() + ".mask");
1147  return new ZExtInst(And, CI.getType());
1148  }
1149 
1150  if (SrcSize == DstSize) {
1151  APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
1152  return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
1153  AndValue));
1154  }
1155  if (SrcSize > DstSize) {
1156  Value *Trunc = Builder.CreateTrunc(A, CI.getType());
1157  APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
1158  return BinaryOperator::CreateAnd(Trunc,
1159  ConstantInt::get(Trunc->getType(),
1160  AndValue));
1161  }
1162  }
1163 
1164  if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1165  return transformZExtICmp(ICI, CI);
1166 
1167  BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
1168  if (SrcI && SrcI->getOpcode() == Instruction::Or) {
1169  // zext (or icmp, icmp) -> or (zext icmp), (zext icmp) if at least one
1170  // of the (zext icmp) can be eliminated. If so, immediately perform the
1171  // according elimination.
1172  ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
1173  ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
1174  if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
1175  (transformZExtICmp(LHS, CI, false) ||
1176  transformZExtICmp(RHS, CI, false))) {
1177  // zext (or icmp, icmp) -> or (zext icmp), (zext icmp)
1178  Value *LCast = Builder.CreateZExt(LHS, CI.getType(), LHS->getName());
1179  Value *RCast = Builder.CreateZExt(RHS, CI.getType(), RHS->getName());
1180  BinaryOperator *Or = BinaryOperator::Create(Instruction::Or, LCast, RCast);
1181 
1182  // Perform the elimination.
1183  if (auto *LZExt = dyn_cast<ZExtInst>(LCast))
1184  transformZExtICmp(LHS, *LZExt);
1185  if (auto *RZExt = dyn_cast<ZExtInst>(RCast))
1186  transformZExtICmp(RHS, *RZExt);
1187 
1188  return Or;
1189  }
1190  }
1191 
1192  // zext(trunc(X) & C) -> (X & zext(C)).
1193  Constant *C;
1194  Value *X;
1195  if (SrcI &&
1196  match(SrcI, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) &&
1197  X->getType() == CI.getType())
1198  return BinaryOperator::CreateAnd(X, ConstantExpr::getZExt(C, CI.getType()));
1199 
1200  // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
1201  Value *And;
1202  if (SrcI && match(SrcI, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
1203  match(And, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Specific(C)))) &&
1204  X->getType() == CI.getType()) {
1205  Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
1206  return BinaryOperator::CreateXor(Builder.CreateAnd(X, ZC), ZC);
1207  }
1208 
1209  return nullptr;
1210 }
1211 
1212 /// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
1213 Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) {
1214  Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1);
1215  ICmpInst::Predicate Pred = ICI->getPredicate();
1216 
1217  // Don't bother if Op1 isn't of vector or integer type.
1218  if (!Op1->getType()->isIntOrIntVectorTy())
1219  return nullptr;
1220 
1221  if ((Pred == ICmpInst::ICMP_SLT && match(Op1, m_ZeroInt())) ||
1222  (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))) {
1223  // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if negative
1224  // (x >s -1) ? -1 : 0 -> not (ashr x, 31) -> all ones if positive
1225  Value *Sh = ConstantInt::get(Op0->getType(),
1226  Op0->getType()->getScalarSizeInBits() - 1);
1227  Value *In = Builder.CreateAShr(Op0, Sh, Op0->getName() + ".lobit");
1228  if (In->getType() != CI.getType())
1229  In = Builder.CreateIntCast(In, CI.getType(), true /*SExt*/);
1230 
1231  if (Pred == ICmpInst::ICMP_SGT)
1232  In = Builder.CreateNot(In, In->getName() + ".not");
1233  return replaceInstUsesWith(CI, In);
1234  }
1235 
1236  if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
1237  // If we know that only one bit of the LHS of the icmp can be set and we
1238  // have an equality comparison with zero or a power of 2, we can transform
1239  // the icmp and sext into bitwise/integer operations.
1240  if (ICI->hasOneUse() &&
1241  ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
1242  KnownBits Known = computeKnownBits(Op0, 0, &CI);
1243 
1244  APInt KnownZeroMask(~Known.Zero);
1245  if (KnownZeroMask.isPowerOf2()) {
1246  Value *In = ICI->getOperand(0);
1247 
1248  // If the icmp tests for a known zero bit we can constant fold it.
1249  if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
1250  Value *V = Pred == ICmpInst::ICMP_NE ?
1253  return replaceInstUsesWith(CI, V);
1254  }
1255 
1256  if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
1257  // sext ((x & 2^n) == 0) -> (x >> n) - 1
1258  // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
1259  unsigned ShiftAmt = KnownZeroMask.countTrailingZeros();
1260  // Perform a right shift to place the desired bit in the LSB.
1261  if (ShiftAmt)
1262  In = Builder.CreateLShr(In,
1263  ConstantInt::get(In->getType(), ShiftAmt));
1264 
1265  // At this point "In" is either 1 or 0. Subtract 1 to turn
1266  // {1, 0} -> {0, -1}.
1267  In = Builder.CreateAdd(In,
1269  "sext");
1270  } else {
1271  // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
1272  // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
1273  unsigned ShiftAmt = KnownZeroMask.countLeadingZeros();
1274  // Perform a left shift to place the desired bit in the MSB.
1275  if (ShiftAmt)
1276  In = Builder.CreateShl(In,
1277  ConstantInt::get(In->getType(), ShiftAmt));
1278 
1279  // Distribute the bit over the whole bit width.
1280  In = Builder.CreateAShr(In, ConstantInt::get(In->getType(),
1281  KnownZeroMask.getBitWidth() - 1), "sext");
1282  }
1283 
1284  if (CI.getType() == In->getType())
1285  return replaceInstUsesWith(CI, In);
1286  return CastInst::CreateIntegerCast(In, CI.getType(), true/*SExt*/);
1287  }
1288  }
1289  }
1290 
1291  return nullptr;
1292 }
1293 
1294 /// Return true if we can take the specified value and return it as type Ty
1295 /// without inserting any new casts and without changing the value of the common
1296 /// low bits. This is used by code that tries to promote integer operations to
1297 /// a wider types will allow us to eliminate the extension.
1298 ///
1299 /// This function works on both vectors and scalars.
1300 ///
1301 static bool canEvaluateSExtd(Value *V, Type *Ty) {
1303  "Can't sign extend type to a smaller type");
1304  if (canAlwaysEvaluateInType(V, Ty))
1305  return true;
1306  if (canNotEvaluateInType(V, Ty))
1307  return false;
1308 
1309  auto *I = cast<Instruction>(V);
1310  switch (I->getOpcode()) {
1311  case Instruction::SExt: // sext(sext(x)) -> sext(x)
1312  case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1313  case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1314  return true;
1315  case Instruction::And:
1316  case Instruction::Or:
1317  case Instruction::Xor:
1318  case Instruction::Add:
1319  case Instruction::Sub:
1320  case Instruction::Mul:
1321  // These operators can all arbitrarily be extended if their inputs can.
1322  return canEvaluateSExtd(I->getOperand(0), Ty) &&
1323  canEvaluateSExtd(I->getOperand(1), Ty);
1324 
1325  //case Instruction::Shl: TODO
1326  //case Instruction::LShr: TODO
1327 
1328  case Instruction::Select:
1329  return canEvaluateSExtd(I->getOperand(1), Ty) &&
1330  canEvaluateSExtd(I->getOperand(2), Ty);
1331 
1332  case Instruction::PHI: {
1333  // We can change a phi if we can change all operands. Note that we never
1334  // get into trouble with cyclic PHIs here because we only consider
1335  // instructions with a single use.
1336  PHINode *PN = cast<PHINode>(I);
1337  for (Value *IncValue : PN->incoming_values())
1338  if (!canEvaluateSExtd(IncValue, Ty)) return false;
1339  return true;
1340  }
1341  default:
1342  // TODO: Can handle more cases here.
1343  break;
1344  }
1345 
1346  return false;
1347 }
1348 
1350  // If this sign extend is only used by a truncate, let the truncate be
1351  // eliminated before we try to optimize this sext.
1352  if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
1353  return nullptr;
1354 
1355  if (Instruction *I = commonCastTransforms(CI))
1356  return I;
1357 
1358  Value *Src = CI.getOperand(0);
1359  Type *SrcTy = Src->getType(), *DestTy = CI.getType();
1360 
1361  // If we know that the value being extended is positive, we can use a zext
1362  // instead.
1363  KnownBits Known = computeKnownBits(Src, 0, &CI);
1364  if (Known.isNonNegative()) {
1365  Value *ZExt = Builder.CreateZExt(Src, DestTy);
1366  return replaceInstUsesWith(CI, ZExt);
1367  }
1368 
1369  // Attempt to extend the entire input expression tree to the destination
1370  // type. Only do this if the dest type is a simple type, don't convert the
1371  // expression tree to something weird like i93 unless the source is also
1372  // strange.
1373  if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) &&
1374  canEvaluateSExtd(Src, DestTy)) {
1375  // Okay, we can transform this! Insert the new expression now.
1376  LLVM_DEBUG(
1377  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1378  " to avoid sign extend: "
1379  << CI << '\n');
1380  Value *Res = EvaluateInDifferentType(Src, DestTy, true);
1381  assert(Res->getType() == DestTy);
1382 
1383  uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
1384  uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1385 
1386  // If the high bits are already filled with sign bit, just replace this
1387  // cast with the result.
1388  if (ComputeNumSignBits(Res, 0, &CI) > DestBitSize - SrcBitSize)
1389  return replaceInstUsesWith(CI, Res);
1390 
1391  // We need to emit a shl + ashr to do the sign extend.
1392  Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
1393  return BinaryOperator::CreateAShr(Builder.CreateShl(Res, ShAmt, "sext"),
1394  ShAmt);
1395  }
1396 
1397  // If the input is a trunc from the destination type, then turn sext(trunc(x))
1398  // into shifts.
1399  Value *X;
1400  if (match(Src, m_OneUse(m_Trunc(m_Value(X)))) && X->getType() == DestTy) {
1401  // sext(trunc(X)) --> ashr(shl(X, C), C)
1402  unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
1403  unsigned DestBitSize = DestTy->getScalarSizeInBits();
1404  Constant *ShAmt = ConstantInt::get(DestTy, DestBitSize - SrcBitSize);
1405  return BinaryOperator::CreateAShr(Builder.CreateShl(X, ShAmt), ShAmt);
1406  }
1407 
1408  if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1409  return transformSExtICmp(ICI, CI);
1410 
1411  // If the input is a shl/ashr pair of a same constant, then this is a sign
1412  // extension from a smaller value. If we could trust arbitrary bitwidth
1413  // integers, we could turn this into a truncate to the smaller bit and then
1414  // use a sext for the whole extension. Since we don't, look deeper and check
1415  // for a truncate. If the source and dest are the same type, eliminate the
1416  // trunc and extend and just do shifts. For example, turn:
1417  // %a = trunc i32 %i to i8
1418  // %b = shl i8 %a, 6
1419  // %c = ashr i8 %b, 6
1420  // %d = sext i8 %c to i32
1421  // into:
1422  // %a = shl i32 %i, 30
1423  // %d = ashr i32 %a, 30
1424  Value *A = nullptr;
1425  // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
1426  ConstantInt *BA = nullptr, *CA = nullptr;
1427  if (match(Src, m_AShr(m_Shl(m_Trunc(m_Value(A)), m_ConstantInt(BA)),
1428  m_ConstantInt(CA))) &&
1429  BA == CA && A->getType() == CI.getType()) {
1430  unsigned MidSize = Src->getType()->getScalarSizeInBits();
1431  unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
1432  unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
1433  Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
1434  A = Builder.CreateShl(A, ShAmtV, CI.getName());
1435  return BinaryOperator::CreateAShr(A, ShAmtV);
1436  }
1437 
1438  return nullptr;
1439 }
1440 
1441 
1442 /// Return a Constant* for the specified floating-point constant if it fits
1443 /// in the specified FP type without changing its value.
1444 static bool fitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
1445  bool losesInfo;
1446  APFloat F = CFP->getValueAPF();
1447  (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
1448  return !losesInfo;
1449 }
1450 
1452  if (CFP->getType() == Type::getPPC_FP128Ty(CFP->getContext()))
1453  return nullptr; // No constant folding of this.
1454  // See if the value can be truncated to half and then reextended.
1455  if (fitsInFPType(CFP, APFloat::IEEEhalf()))
1456  return Type::getHalfTy(CFP->getContext());
1457  // See if the value can be truncated to float and then reextended.
1458  if (fitsInFPType(CFP, APFloat::IEEEsingle()))
1459  return Type::getFloatTy(CFP->getContext());
1460  if (CFP->getType()->isDoubleTy())
1461  return nullptr; // Won't shrink.
1462  if (fitsInFPType(CFP, APFloat::IEEEdouble()))
1463  return Type::getDoubleTy(CFP->getContext());
1464  // Don't try to shrink to various long double types.
1465  return nullptr;
1466 }
1467 
1468 // Determine if this is a vector of ConstantFPs and if so, return the minimal
1469 // type we can safely truncate all elements to.
1470 // TODO: Make these support undef elements.
1472  auto *CV = dyn_cast<Constant>(V);
1473  if (!CV || !CV->getType()->isVectorTy())
1474  return nullptr;
1475 
1476  Type *MinType = nullptr;
1477 
1478  unsigned NumElts = CV->getType()->getVectorNumElements();
1479  for (unsigned i = 0; i != NumElts; ++i) {
1480  auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i));
1481  if (!CFP)
1482  return nullptr;
1483 
1484  Type *T = shrinkFPConstant(CFP);
1485  if (!T)
1486  return nullptr;
1487 
1488  // If we haven't found a type yet or this type has a larger mantissa than
1489  // our previous type, this is our new minimal type.
1490  if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth())
1491  MinType = T;
1492  }
1493 
1494  // Make a vector type from the minimal type.
1495  return VectorType::get(MinType, NumElts);
1496 }
1497 
1498 /// Find the minimum FP type we can safely truncate to.
1500  if (auto *FPExt = dyn_cast<FPExtInst>(V))
1501  return FPExt->getOperand(0)->getType();
1502 
1503  // If this value is a constant, return the constant in the smallest FP type
1504  // that can accurately represent it. This allows us to turn
1505  // (float)((double)X+2.0) into x+2.0f.
1506  if (auto *CFP = dyn_cast<ConstantFP>(V))
1507  if (Type *T = shrinkFPConstant(CFP))
1508  return T;
1509 
1510  // Try to shrink a vector of FP constants.
1511  if (Type *T = shrinkFPConstantVector(V))
1512  return T;
1513 
1514  return V->getType();
1515 }
1516 
1518  if (Instruction *I = commonCastTransforms(FPT))
1519  return I;
1520 
1521  // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
1522  // simplify this expression to avoid one or more of the trunc/extend
1523  // operations if we can do so without changing the numerical results.
1524  //
1525  // The exact manner in which the widths of the operands interact to limit
1526  // what we can and cannot do safely varies from operation to operation, and
1527  // is explained below in the various case statements.
1528  Type *Ty = FPT.getType();
1530  if (OpI && OpI->hasOneUse()) {
1531  Type *LHSMinType = getMinimumFPType(OpI->getOperand(0));
1532  Type *RHSMinType = getMinimumFPType(OpI->getOperand(1));
1533  unsigned OpWidth = OpI->getType()->getFPMantissaWidth();
1534  unsigned LHSWidth = LHSMinType->getFPMantissaWidth();
1535  unsigned RHSWidth = RHSMinType->getFPMantissaWidth();
1536  unsigned SrcWidth = std::max(LHSWidth, RHSWidth);
1537  unsigned DstWidth = Ty->getFPMantissaWidth();
1538  switch (OpI->getOpcode()) {
1539  default: break;
1540  case Instruction::FAdd:
1541  case Instruction::FSub:
1542  // For addition and subtraction, the infinitely precise result can
1543  // essentially be arbitrarily wide; proving that double rounding
1544  // will not occur because the result of OpI is exact (as we will for
1545  // FMul, for example) is hopeless. However, we *can* nonetheless
1546  // frequently know that double rounding cannot occur (or that it is
1547  // innocuous) by taking advantage of the specific structure of
1548  // infinitely-precise results that admit double rounding.
1549  //
1550  // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
1551  // to represent both sources, we can guarantee that the double
1552  // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
1553  // "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
1554  // for proof of this fact).
1555  //
1556  // Note: Figueroa does not consider the case where DstFormat !=
1557  // SrcFormat. It's possible (likely even!) that this analysis
1558  // could be tightened for those cases, but they are rare (the main
1559  // case of interest here is (float)((double)float + float)).
1560  if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) {
1561  Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1562  Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
1563  Instruction *RI = BinaryOperator::Create(OpI->getOpcode(), LHS, RHS);
1564  RI->copyFastMathFlags(OpI);
1565  return RI;
1566  }
1567  break;
1568  case Instruction::FMul:
1569  // For multiplication, the infinitely precise result has at most
1570  // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
1571  // that such a value can be exactly represented, then no double
1572  // rounding can possibly occur; we can safely perform the operation
1573  // in the destination format if it can represent both sources.
1574  if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) {
1575  Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1576  Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
1577  return BinaryOperator::CreateFMulFMF(LHS, RHS, OpI);
1578  }
1579  break;
1580  case Instruction::FDiv:
1581  // For division, we use again use the bound from Figueroa's
1582  // dissertation. I am entirely certain that this bound can be
1583  // tightened in the unbalanced operand case by an analysis based on
1584  // the diophantine rational approximation bound, but the well-known
1585  // condition used here is a good conservative first pass.
1586  // TODO: Tighten bound via rigorous analysis of the unbalanced case.
1587  if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) {
1588  Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1589  Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
1590  return BinaryOperator::CreateFDivFMF(LHS, RHS, OpI);
1591  }
1592  break;
1593  case Instruction::FRem: {
1594  // Remainder is straightforward. Remainder is always exact, so the
1595  // type of OpI doesn't enter into things at all. We simply evaluate
1596  // in whichever source type is larger, then convert to the
1597  // destination type.
1598  if (SrcWidth == OpWidth)
1599  break;
1600  Value *LHS, *RHS;
1601  if (LHSWidth == SrcWidth) {
1602  LHS = Builder.CreateFPTrunc(OpI->getOperand(0), LHSMinType);
1603  RHS = Builder.CreateFPTrunc(OpI->getOperand(1), LHSMinType);
1604  } else {
1605  LHS = Builder.CreateFPTrunc(OpI->getOperand(0), RHSMinType);
1606  RHS = Builder.CreateFPTrunc(OpI->getOperand(1), RHSMinType);
1607  }
1608 
1609  Value *ExactResult = Builder.CreateFRemFMF(LHS, RHS, OpI);
1610  return CastInst::CreateFPCast(ExactResult, Ty);
1611  }
1612  }
1613 
1614  // (fptrunc (fneg x)) -> (fneg (fptrunc x))
1615  if (BinaryOperator::isFNeg(OpI)) {
1616  Value *InnerTrunc = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
1617  return BinaryOperator::CreateFNegFMF(InnerTrunc, OpI);
1618  }
1619  }
1620 
1621  if (auto *II = dyn_cast<IntrinsicInst>(FPT.getOperand(0))) {
1622  switch (II->getIntrinsicID()) {
1623  default: break;
1624  case Intrinsic::ceil:
1625  case Intrinsic::fabs:
1626  case Intrinsic::floor:
1627  case Intrinsic::nearbyint:
1628  case Intrinsic::rint:
1629  case Intrinsic::round:
1630  case Intrinsic::trunc: {
1631  Value *Src = II->getArgOperand(0);
1632  if (!Src->hasOneUse())
1633  break;
1634 
1635  // Except for fabs, this transformation requires the input of the unary FP
1636  // operation to be itself an fpext from the type to which we're
1637  // truncating.
1638  if (II->getIntrinsicID() != Intrinsic::fabs) {
1639  FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Src);
1640  if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty)
1641  break;
1642  }
1643 
1644  // Do unary FP operation on smaller type.
1645  // (fptrunc (fabs x)) -> (fabs (fptrunc x))
1646  Value *InnerTrunc = Builder.CreateFPTrunc(Src, Ty);
1647  Function *Overload = Intrinsic::getDeclaration(FPT.getModule(),
1648  II->getIntrinsicID(), Ty);
1650  II->getOperandBundlesAsDefs(OpBundles);
1651  CallInst *NewCI = CallInst::Create(Overload, { InnerTrunc }, OpBundles,
1652  II->getName());
1653  NewCI->copyFastMathFlags(II);
1654  return NewCI;
1655  }
1656  }
1657  }
1658 
1659  if (Instruction *I = shrinkInsertElt(FPT, Builder))
1660  return I;
1661 
1662  return nullptr;
1663 }
1664 
1666  return commonCastTransforms(CI);
1667 }
1668 
1669 // fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
1670 // This is safe if the intermediate type has enough bits in its mantissa to
1671 // accurately represent all values of X. For example, this won't work with
1672 // i64 -> float -> i64.
1674  if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0)))
1675  return nullptr;
1676  Instruction *OpI = cast<Instruction>(FI.getOperand(0));
1677 
1678  Value *SrcI = OpI->getOperand(0);
1679  Type *FITy = FI.getType();
1680  Type *OpITy = OpI->getType();
1681  Type *SrcTy = SrcI->getType();
1682  bool IsInputSigned = isa<SIToFPInst>(OpI);
1683  bool IsOutputSigned = isa<FPToSIInst>(FI);
1684 
1685  // We can safely assume the conversion won't overflow the output range,
1686  // because (for example) (uint8_t)18293.f is undefined behavior.
1687 
1688  // Since we can assume the conversion won't overflow, our decision as to
1689  // whether the input will fit in the float should depend on the minimum
1690  // of the input range and output range.
1691 
1692  // This means this is also safe for a signed input and unsigned output, since
1693  // a negative input would lead to undefined behavior.
1694  int InputSize = (int)SrcTy->getScalarSizeInBits() - IsInputSigned;
1695  int OutputSize = (int)FITy->getScalarSizeInBits() - IsOutputSigned;
1696  int ActualSize = std::min(InputSize, OutputSize);
1697 
1698  if (ActualSize <= OpITy->getFPMantissaWidth()) {
1699  if (FITy->getScalarSizeInBits() > SrcTy->getScalarSizeInBits()) {
1700  if (IsInputSigned && IsOutputSigned)
1701  return new SExtInst(SrcI, FITy);
1702  return new ZExtInst(SrcI, FITy);
1703  }
1704  if (FITy->getScalarSizeInBits() < SrcTy->getScalarSizeInBits())
1705  return new TruncInst(SrcI, FITy);
1706  if (SrcTy == FITy)
1707  return replaceInstUsesWith(FI, SrcI);
1708  return new BitCastInst(SrcI, FITy);
1709  }
1710  return nullptr;
1711 }
1712 
1714  Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1715  if (!OpI)
1716  return commonCastTransforms(FI);
1717 
1718  if (Instruction *I = FoldItoFPtoI(FI))
1719  return I;
1720 
1721  return commonCastTransforms(FI);
1722 }
1723 
1725  Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1726  if (!OpI)
1727  return commonCastTransforms(FI);
1728 
1729  if (Instruction *I = FoldItoFPtoI(FI))
1730  return I;
1731 
1732  return commonCastTransforms(FI);
1733 }
1734 
1736  return commonCastTransforms(CI);
1737 }
1738 
1740  return commonCastTransforms(CI);
1741 }
1742 
1744  // If the source integer type is not the intptr_t type for this target, do a
1745  // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
1746  // cast to be exposed to other transforms.
1747  unsigned AS = CI.getAddressSpace();
1748  if (CI.getOperand(0)->getType()->getScalarSizeInBits() !=
1749  DL.getPointerSizeInBits(AS)) {
1750  Type *Ty = DL.getIntPtrType(CI.getContext(), AS);
1751  if (CI.getType()->isVectorTy()) // Handle vectors of pointers.
1752  Ty = VectorType::get(Ty, CI.getType()->getVectorNumElements());
1753 
1754  Value *P = Builder.CreateZExtOrTrunc(CI.getOperand(0), Ty);
1755  return new IntToPtrInst(P, CI.getType());
1756  }
1757 
1758  if (Instruction *I = commonCastTransforms(CI))
1759  return I;
1760 
1761  return nullptr;
1762 }
1763 
1764 /// Implement the transforms for cast of pointer (bitcast/ptrtoint)
1766  Value *Src = CI.getOperand(0);
1767 
1768  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
1769  // If casting the result of a getelementptr instruction with no offset, turn
1770  // this into a cast of the original pointer!
1771  if (GEP->hasAllZeroIndices() &&
1772  // If CI is an addrspacecast and GEP changes the poiner type, merging
1773  // GEP into CI would undo canonicalizing addrspacecast with different
1774  // pointer types, causing infinite loops.
1775  (!isa<AddrSpaceCastInst>(CI) ||
1776  GEP->getType() == GEP->getPointerOperandType())) {
1777  // Changing the cast operand is usually not a good idea but it is safe
1778  // here because the pointer operand is being replaced with another
1779  // pointer operand so the opcode doesn't need to change.
1780  Worklist.Add(GEP);
1781  CI.setOperand(0, GEP->getOperand(0));
1782  return &CI;
1783  }
1784  }
1785 
1786  return commonCastTransforms(CI);
1787 }
1788 
1790  // If the destination integer type is not the intptr_t type for this target,
1791  // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
1792  // to be exposed to other transforms.
1793 
1794  Type *Ty = CI.getType();
1795  unsigned AS = CI.getPointerAddressSpace();
1796 
1797  if (Ty->getScalarSizeInBits() == DL.getIndexSizeInBits(AS))
1798  return commonPointerCastTransforms(CI);
1799 
1800  Type *PtrTy = DL.getIntPtrType(CI.getContext(), AS);
1801  if (Ty->isVectorTy()) // Handle vectors of pointers.
1802  PtrTy = VectorType::get(PtrTy, Ty->getVectorNumElements());
1803 
1804  Value *P = Builder.CreatePtrToInt(CI.getOperand(0), PtrTy);
1805  return CastInst::CreateIntegerCast(P, Ty, /*isSigned=*/false);
1806 }
1807 
1808 /// This input value (which is known to have vector type) is being zero extended
1809 /// or truncated to the specified vector type.
1810 /// Try to replace it with a shuffle (and vector/vector bitcast) if possible.
1811 ///
1812 /// The source and destination vector types may have different element types.
1814  InstCombiner &IC) {
1815  // We can only do this optimization if the output is a multiple of the input
1816  // element size, or the input is a multiple of the output element size.
1817  // Convert the input type to have the same element type as the output.
1818  VectorType *SrcTy = cast<VectorType>(InVal->getType());
1819 
1820  if (SrcTy->getElementType() != DestTy->getElementType()) {
1821  // The input types don't need to be identical, but for now they must be the
1822  // same size. There is no specific reason we couldn't handle things like
1823  // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
1824  // there yet.
1825  if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
1827  return nullptr;
1828 
1829  SrcTy = VectorType::get(DestTy->getElementType(), SrcTy->getNumElements());
1830  InVal = IC.Builder.CreateBitCast(InVal, SrcTy);
1831  }
1832 
1833  // Now that the element types match, get the shuffle mask and RHS of the
1834  // shuffle to use, which depends on whether we're increasing or decreasing the
1835  // size of the input.
1836  SmallVector<uint32_t, 16> ShuffleMask;
1837  Value *V2;
1838 
1839  if (SrcTy->getNumElements() > DestTy->getNumElements()) {
1840  // If we're shrinking the number of elements, just shuffle in the low
1841  // elements from the input and use undef as the second shuffle input.
1842  V2 = UndefValue::get(SrcTy);
1843  for (unsigned i = 0, e = DestTy->getNumElements(); i != e; ++i)
1844  ShuffleMask.push_back(i);
1845 
1846  } else {
1847  // If we're increasing the number of elements, shuffle in all of the
1848  // elements from InVal and fill the rest of the result elements with zeros
1849  // from a constant zero.
1850  V2 = Constant::getNullValue(SrcTy);
1851  unsigned SrcElts = SrcTy->getNumElements();
1852  for (unsigned i = 0, e = SrcElts; i != e; ++i)
1853  ShuffleMask.push_back(i);
1854 
1855  // The excess elements reference the first element of the zero input.
1856  for (unsigned i = 0, e = DestTy->getNumElements()-SrcElts; i != e; ++i)
1857  ShuffleMask.push_back(SrcElts);
1858  }
1859 
1860  return new ShuffleVectorInst(InVal, V2,
1862  ShuffleMask));
1863 }
1864 
1865 static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
1866  return Value % Ty->getPrimitiveSizeInBits() == 0;
1867 }
1868 
1869 static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
1870  return Value / Ty->getPrimitiveSizeInBits();
1871 }
1872 
1873 /// V is a value which is inserted into a vector of VecEltTy.
1874 /// Look through the value to see if we can decompose it into
1875 /// insertions into the vector. See the example in the comment for
1876 /// OptimizeIntegerToVectorInsertions for the pattern this handles.
1877 /// The type of V is always a non-zero multiple of VecEltTy's size.
1878 /// Shift is the number of bits between the lsb of V and the lsb of
1879 /// the vector.
1880 ///
1881 /// This returns false if the pattern can't be matched or true if it can,
1882 /// filling in Elements with the elements found here.
1883 static bool collectInsertionElements(Value *V, unsigned Shift,
1884  SmallVectorImpl<Value *> &Elements,
1885  Type *VecEltTy, bool isBigEndian) {
1886  assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
1887  "Shift should be a multiple of the element type size");
1888 
1889  // Undef values never contribute useful bits to the result.
1890  if (isa<UndefValue>(V)) return true;
1891 
1892  // If we got down to a value of the right type, we win, try inserting into the
1893  // right element.
1894  if (V->getType() == VecEltTy) {
1895  // Inserting null doesn't actually insert any elements.
1896  if (Constant *C = dyn_cast<Constant>(V))
1897  if (C->isNullValue())
1898  return true;
1899 
1900  unsigned ElementIndex = getTypeSizeIndex(Shift, VecEltTy);
1901  if (isBigEndian)
1902  ElementIndex = Elements.size() - ElementIndex - 1;
1903 
1904  // Fail if multiple elements are inserted into this slot.
1905  if (Elements[ElementIndex])
1906  return false;
1907 
1908  Elements[ElementIndex] = V;
1909  return true;
1910  }
1911 
1912  if (Constant *C = dyn_cast<Constant>(V)) {
1913  // Figure out the # elements this provides, and bitcast it or slice it up
1914  // as required.
1915  unsigned NumElts = getTypeSizeIndex(C->getType()->getPrimitiveSizeInBits(),
1916  VecEltTy);
1917  // If the constant is the size of a vector element, we just need to bitcast
1918  // it to the right type so it gets properly inserted.
1919  if (NumElts == 1)
1921  Shift, Elements, VecEltTy, isBigEndian);
1922 
1923  // Okay, this is a constant that covers multiple elements. Slice it up into
1924  // pieces and insert each element-sized piece into the vector.
1925  if (!isa<IntegerType>(C->getType()))
1928  unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
1929  Type *ElementIntTy = IntegerType::get(C->getContext(), ElementSize);
1930 
1931  for (unsigned i = 0; i != NumElts; ++i) {
1932  unsigned ShiftI = Shift+i*ElementSize;
1934  ShiftI));
1935  Piece = ConstantExpr::getTrunc(Piece, ElementIntTy);
1936  if (!collectInsertionElements(Piece, ShiftI, Elements, VecEltTy,
1937  isBigEndian))
1938  return false;
1939  }
1940  return true;
1941  }
1942 
1943  if (!V->hasOneUse()) return false;
1944 
1946  if (!I) return false;
1947  switch (I->getOpcode()) {
1948  default: return false; // Unhandled case.
1949  case Instruction::BitCast:
1950  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1951  isBigEndian);
1952  case Instruction::ZExt:
1953  if (!isMultipleOfTypeSize(
1955  VecEltTy))
1956  return false;
1957  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1958  isBigEndian);
1959  case Instruction::Or:
1960  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1961  isBigEndian) &&
1962  collectInsertionElements(I->getOperand(1), Shift, Elements, VecEltTy,
1963  isBigEndian);
1964  case Instruction::Shl: {
1965  // Must be shifting by a constant that is a multiple of the element size.
1967  if (!CI) return false;
1968  Shift += CI->getZExtValue();
1969  if (!isMultipleOfTypeSize(Shift, VecEltTy)) return false;
1970  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1971  isBigEndian);
1972  }
1973 
1974  }
1975 }
1976 
1977 
1978 /// If the input is an 'or' instruction, we may be doing shifts and ors to
1979 /// assemble the elements of the vector manually.
1980 /// Try to rip the code out and replace it with insertelements. This is to
1981 /// optimize code like this:
1982 ///
1983 /// %tmp37 = bitcast float %inc to i32
1984 /// %tmp38 = zext i32 %tmp37 to i64
1985 /// %tmp31 = bitcast float %inc5 to i32
1986 /// %tmp32 = zext i32 %tmp31 to i64
1987 /// %tmp33 = shl i64 %tmp32, 32
1988 /// %ins35 = or i64 %tmp33, %tmp38
1989 /// %tmp43 = bitcast i64 %ins35 to <2 x float>
1990 ///
1991 /// Into two insertelements that do "buildvector{%inc, %inc5}".
1993  InstCombiner &IC) {
1994  VectorType *DestVecTy = cast<VectorType>(CI.getType());
1995  Value *IntInput = CI.getOperand(0);
1996 
1997  SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
1998  if (!collectInsertionElements(IntInput, 0, Elements,
1999  DestVecTy->getElementType(),
2000  IC.getDataLayout().isBigEndian()))
2001  return nullptr;
2002 
2003  // If we succeeded, we know that all of the element are specified by Elements
2004  // or are zero if Elements has a null entry. Recast this as a set of
2005  // insertions.
2007  for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
2008  if (!Elements[i]) continue; // Unset element.
2009 
2010  Result = IC.Builder.CreateInsertElement(Result, Elements[i],
2011  IC.Builder.getInt32(i));
2012  }
2013 
2014  return Result;
2015 }
2016 
2017 /// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
2018 /// vector followed by extract element. The backend tends to handle bitcasts of
2019 /// vectors better than bitcasts of scalars because vector registers are
2020 /// usually not type-specific like scalar integer or scalar floating-point.
2022  InstCombiner &IC) {
2023  // TODO: Create and use a pattern matcher for ExtractElementInst.
2024  auto *ExtElt = dyn_cast<ExtractElementInst>(BitCast.getOperand(0));
2025  if (!ExtElt || !ExtElt->hasOneUse())
2026  return nullptr;
2027 
2028  // The bitcast must be to a vectorizable type, otherwise we can't make a new
2029  // type to extract from.
2030  Type *DestType = BitCast.getType();
2031  if (!VectorType::isValidElementType(DestType))
2032  return nullptr;
2033 
2034  unsigned NumElts = ExtElt->getVectorOperandType()->getNumElements();
2035  auto *NewVecType = VectorType::get(DestType, NumElts);
2036  auto *NewBC = IC.Builder.CreateBitCast(ExtElt->getVectorOperand(),
2037  NewVecType, "bc");
2038  return ExtractElementInst::Create(NewBC, ExtElt->getIndexOperand());
2039 }
2040 
2041 /// Change the type of a bitwise logic operation if we can eliminate a bitcast.
2043  InstCombiner::BuilderTy &Builder) {
2044  Type *DestTy = BitCast.getType();
2045  BinaryOperator *BO;
2046  if (!DestTy->isIntOrIntVectorTy() ||
2047  !match(BitCast.getOperand(0), m_OneUse(m_BinOp(BO))) ||
2048  !BO->isBitwiseLogicOp())
2049  return nullptr;
2050 
2051  // FIXME: This transform is restricted to vector types to avoid backend
2052  // problems caused by creating potentially illegal operations. If a fix-up is
2053  // added to handle that situation, we can remove this check.
2054  if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy())
2055  return nullptr;
2056 
2057  Value *X;
2058  if (match(BO->getOperand(0), m_OneUse(m_BitCast(m_Value(X)))) &&
2059  X->getType() == DestTy && !isa<Constant>(X)) {
2060  // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y))
2061  Value *CastedOp1 = Builder.CreateBitCast(BO->getOperand(1), DestTy);
2062  return BinaryOperator::Create(BO->getOpcode(), X, CastedOp1);
2063  }
2064 
2065  if (match(BO->getOperand(1), m_OneUse(m_BitCast(m_Value(X)))) &&
2066  X->getType() == DestTy && !isa<Constant>(X)) {
2067  // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X)
2068  Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
2069  return BinaryOperator::Create(BO->getOpcode(), CastedOp0, X);
2070  }
2071 
2072  // Canonicalize vector bitcasts to come before vector bitwise logic with a
2073  // constant. This eases recognition of special constants for later ops.
2074  // Example:
2075  // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
2076  Constant *C;
2077  if (match(BO->getOperand(1), m_Constant(C))) {
2078  // bitcast (logic X, C) --> logic (bitcast X, C')
2079  Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
2080  Value *CastedC = ConstantExpr::getBitCast(C, DestTy);
2081  return BinaryOperator::Create(BO->getOpcode(), CastedOp0, CastedC);
2082  }
2083 
2084  return nullptr;
2085 }
2086 
2087 /// Change the type of a select if we can eliminate a bitcast.
2089  InstCombiner::BuilderTy &Builder) {
2090  Value *Cond, *TVal, *FVal;
2091  if (!match(BitCast.getOperand(0),
2092  m_OneUse(m_Select(m_Value(Cond), m_Value(TVal), m_Value(FVal)))))
2093  return nullptr;
2094 
2095  // A vector select must maintain the same number of elements in its operands.
2096  Type *CondTy = Cond->getType();
2097  Type *DestTy = BitCast.getType();
2098  if (CondTy->isVectorTy()) {
2099  if (!DestTy->isVectorTy())
2100  return nullptr;
2101  if (DestTy->getVectorNumElements() != CondTy->getVectorNumElements())
2102  return nullptr;
2103  }
2104 
2105  // FIXME: This transform is restricted from changing the select between
2106  // scalars and vectors to avoid backend problems caused by creating
2107  // potentially illegal operations. If a fix-up is added to handle that
2108  // situation, we can remove this check.
2109  if (DestTy->isVectorTy() != TVal->getType()->isVectorTy())
2110  return nullptr;
2111 
2112  auto *Sel = cast<Instruction>(BitCast.getOperand(0));
2113  Value *X;
2114  if (match(TVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy &&
2115  !isa<Constant>(X)) {
2116  // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y))
2117  Value *CastedVal = Builder.CreateBitCast(FVal, DestTy);
2118  return SelectInst::Create(Cond, X, CastedVal, "", nullptr, Sel);
2119  }
2120 
2121  if (match(FVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy &&
2122  !isa<Constant>(X)) {
2123  // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X)
2124  Value *CastedVal = Builder.CreateBitCast(TVal, DestTy);
2125  return SelectInst::Create(Cond, CastedVal, X, "", nullptr, Sel);
2126  }
2127 
2128  return nullptr;
2129 }
2130 
2131 /// Check if all users of CI are StoreInsts.
2132 static bool hasStoreUsersOnly(CastInst &CI) {
2133  for (User *U : CI.users()) {
2134  if (!isa<StoreInst>(U))
2135  return false;
2136  }
2137  return true;
2138 }
2139 
2140 /// This function handles following case
2141 ///
2142 /// A -> B cast
2143 /// PHI
2144 /// B -> A cast
2145 ///
2146 /// All the related PHI nodes can be replaced by new PHI nodes with type A.
2147 /// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
2148 Instruction *InstCombiner::optimizeBitCastFromPhi(CastInst &CI, PHINode *PN) {
2149  // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp.
2150  if (hasStoreUsersOnly(CI))
2151  return nullptr;
2152 
2153  Value *Src = CI.getOperand(0);
2154  Type *SrcTy = Src->getType(); // Type B
2155  Type *DestTy = CI.getType(); // Type A
2156 
2157  SmallVector<PHINode *, 4> PhiWorklist;
2158  SmallSetVector<PHINode *, 4> OldPhiNodes;
2159 
2160  // Find all of the A->B casts and PHI nodes.
2161  // We need to inpect all related PHI nodes, but PHIs can be cyclic, so
2162  // OldPhiNodes is used to track all known PHI nodes, before adding a new
2163  // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
2164  PhiWorklist.push_back(PN);
2165  OldPhiNodes.insert(PN);
2166  while (!PhiWorklist.empty()) {
2167  auto *OldPN = PhiWorklist.pop_back_val();
2168  for (Value *IncValue : OldPN->incoming_values()) {
2169  if (isa<Constant>(IncValue))
2170  continue;
2171 
2172  if (auto *LI = dyn_cast<LoadInst>(IncValue)) {
2173  // If there is a sequence of one or more load instructions, each loaded
2174  // value is used as address of later load instruction, bitcast is
2175  // necessary to change the value type, don't optimize it. For
2176  // simplicity we give up if the load address comes from another load.
2177  Value *Addr = LI->getOperand(0);
2178  if (Addr == &CI || isa<LoadInst>(Addr))
2179  return nullptr;
2180  if (LI->hasOneUse() && LI->isSimple())
2181  continue;
2182  // If a LoadInst has more than one use, changing the type of loaded
2183  // value may create another bitcast.
2184  return nullptr;
2185  }
2186 
2187  if (auto *PNode = dyn_cast<PHINode>(IncValue)) {
2188  if (OldPhiNodes.insert(PNode))
2189  PhiWorklist.push_back(PNode);
2190  continue;
2191  }
2192 
2193  auto *BCI = dyn_cast<BitCastInst>(IncValue);
2194  // We can't handle other instructions.
2195  if (!BCI)
2196  return nullptr;
2197 
2198  // Verify it's a A->B cast.
2199  Type *TyA = BCI->getOperand(0)->getType();
2200  Type *TyB = BCI->getType();
2201  if (TyA != DestTy || TyB != SrcTy)
2202  return nullptr;
2203  }
2204  }
2205 
2206  // For each old PHI node, create a corresponding new PHI node with a type A.
2208  for (auto *OldPN : OldPhiNodes) {
2209  Builder.SetInsertPoint(OldPN);
2210  PHINode *NewPN = Builder.CreatePHI(DestTy, OldPN->getNumOperands());
2211  NewPNodes[OldPN] = NewPN;
2212  }
2213 
2214  // Fill in the operands of new PHI nodes.
2215  for (auto *OldPN : OldPhiNodes) {
2216  PHINode *NewPN = NewPNodes[OldPN];
2217  for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
2218  Value *V = OldPN->getOperand(j);
2219  Value *NewV = nullptr;
2220  if (auto *C = dyn_cast<Constant>(V)) {
2221  NewV = ConstantExpr::getBitCast(C, DestTy);
2222  } else if (auto *LI = dyn_cast<LoadInst>(V)) {
2223  Builder.SetInsertPoint(LI->getNextNode());
2224  NewV = Builder.CreateBitCast(LI, DestTy);
2225  Worklist.Add(LI);
2226  } else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
2227  NewV = BCI->getOperand(0);
2228  } else if (auto *PrevPN = dyn_cast<PHINode>(V)) {
2229  NewV = NewPNodes[PrevPN];
2230  }
2231  assert(NewV);
2232  NewPN->addIncoming(NewV, OldPN->getIncomingBlock(j));
2233  }
2234  }
2235 
2236  // If there is a store with type B, change it to type A.
2237  for (User *U : PN->users()) {
2238  auto *SI = dyn_cast<StoreInst>(U);
2239  if (SI && SI->isSimple() && SI->getOperand(0) == PN) {
2240  Builder.SetInsertPoint(SI);
2241  auto *NewBC =
2242  cast<BitCastInst>(Builder.CreateBitCast(NewPNodes[PN], SrcTy));
2243  SI->setOperand(0, NewBC);
2244  Worklist.Add(SI);
2245  assert(hasStoreUsersOnly(*NewBC));
2246  }
2247  }
2248 
2249  return replaceInstUsesWith(CI, NewPNodes[PN]);
2250 }
2251 
2253  // If the operands are integer typed then apply the integer transforms,
2254  // otherwise just apply the common ones.
2255  Value *Src = CI.getOperand(0);
2256  Type *SrcTy = Src->getType();
2257  Type *DestTy = CI.getType();
2258 
2259  // Get rid of casts from one type to the same type. These are useless and can
2260  // be replaced by the operand.
2261  if (DestTy == Src->getType())
2262  return replaceInstUsesWith(CI, Src);
2263 
2264  if (PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
2265  PointerType *SrcPTy = cast<PointerType>(SrcTy);
2266  Type *DstElTy = DstPTy->getElementType();
2267  Type *SrcElTy = SrcPTy->getElementType();
2268 
2269  // Casting pointers between the same type, but with different address spaces
2270  // is an addrspace cast rather than a bitcast.
2271  if ((DstElTy == SrcElTy) &&
2272  (DstPTy->getAddressSpace() != SrcPTy->getAddressSpace()))
2273  return new AddrSpaceCastInst(Src, DestTy);
2274 
2275  // If we are casting a alloca to a pointer to a type of the same
2276  // size, rewrite the allocation instruction to allocate the "right" type.
2277  // There is no need to modify malloc calls because it is their bitcast that
2278  // needs to be cleaned up.
2279  if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
2280  if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
2281  return V;
2282 
2283  // When the type pointed to is not sized the cast cannot be
2284  // turned into a gep.
2285  Type *PointeeType =
2286  cast<PointerType>(Src->getType()->getScalarType())->getElementType();
2287  if (!PointeeType->isSized())
2288  return nullptr;
2289 
2290  // If the source and destination are pointers, and this cast is equivalent
2291  // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
2292  // This can enhance SROA and other transforms that want type-safe pointers.
2293  unsigned NumZeros = 0;
2294  while (SrcElTy != DstElTy &&
2295  isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
2296  SrcElTy->getNumContainedTypes() /* not "{}" */) {
2297  SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(0U);
2298  ++NumZeros;
2299  }
2300 
2301  // If we found a path from the src to dest, create the getelementptr now.
2302  if (SrcElTy == DstElTy) {
2303  SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder.getInt32(0));
2304  return GetElementPtrInst::CreateInBounds(Src, Idxs);
2305  }
2306  }
2307 
2308  if (VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
2309  if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) {
2310  Value *Elem = Builder.CreateBitCast(Src, DestVTy->getElementType());
2311  return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
2313  // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
2314  }
2315 
2316  if (isa<IntegerType>(SrcTy)) {
2317  // If this is a cast from an integer to vector, check to see if the input
2318  // is a trunc or zext of a bitcast from vector. If so, we can replace all
2319  // the casts with a shuffle and (potentially) a bitcast.
2320  if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) {
2321  CastInst *SrcCast = cast<CastInst>(Src);
2322  if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
2323  if (isa<VectorType>(BCIn->getOperand(0)->getType()))
2324  if (Instruction *I = optimizeVectorResize(BCIn->getOperand(0),
2325  cast<VectorType>(DestTy), *this))
2326  return I;
2327  }
2328 
2329  // If the input is an 'or' instruction, we may be doing shifts and ors to
2330  // assemble the elements of the vector manually. Try to rip the code out
2331  // and replace it with insertelements.
2332  if (Value *V = optimizeIntegerToVectorInsertions(CI, *this))
2333  return replaceInstUsesWith(CI, V);
2334  }
2335  }
2336 
2337  if (VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
2338  if (SrcVTy->getNumElements() == 1) {
2339  // If our destination is not a vector, then make this a straight
2340  // scalar-scalar cast.
2341  if (!DestTy->isVectorTy()) {
2342  Value *Elem =
2343  Builder.CreateExtractElement(Src,
2345  return CastInst::Create(Instruction::BitCast, Elem, DestTy);
2346  }
2347 
2348  // Otherwise, see if our source is an insert. If so, then use the scalar
2349  // component directly.
2350  if (InsertElementInst *IEI =
2351  dyn_cast<InsertElementInst>(CI.getOperand(0)))
2352  return CastInst::Create(Instruction::BitCast, IEI->getOperand(1),
2353  DestTy);
2354  }
2355  }
2356 
2357  if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
2358  // Okay, we have (bitcast (shuffle ..)). Check to see if this is
2359  // a bitcast to a vector with the same # elts.
2360  if (SVI->hasOneUse() && DestTy->isVectorTy() &&
2361  DestTy->getVectorNumElements() == SVI->getType()->getNumElements() &&
2362  SVI->getType()->getNumElements() ==
2363  SVI->getOperand(0)->getType()->getVectorNumElements()) {
2364  BitCastInst *Tmp;
2365  // If either of the operands is a cast from CI.getType(), then
2366  // evaluating the shuffle in the casted destination's type will allow
2367  // us to eliminate at least one cast.
2368  if (((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(0))) &&
2369  Tmp->getOperand(0)->getType() == DestTy) ||
2370  ((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(1))) &&
2371  Tmp->getOperand(0)->getType() == DestTy)) {
2372  Value *LHS = Builder.CreateBitCast(SVI->getOperand(0), DestTy);
2373  Value *RHS = Builder.CreateBitCast(SVI->getOperand(1), DestTy);
2374  // Return a new shuffle vector. Use the same element ID's, as we
2375  // know the vector types match #elts.
2376  return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
2377  }
2378  }
2379  }
2380 
2381  // Handle the A->B->A cast, and there is an intervening PHI node.
2382  if (PHINode *PN = dyn_cast<PHINode>(Src))
2383  if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
2384  return I;
2385 
2386  if (Instruction *I = canonicalizeBitCastExtElt(CI, *this))
2387  return I;
2388 
2389  if (Instruction *I = foldBitCastBitwiseLogic(CI, Builder))
2390  return I;
2391 
2392  if (Instruction *I = foldBitCastSelect(CI, Builder))
2393  return I;
2394 
2395  if (SrcTy->isPointerTy())
2396  return commonPointerCastTransforms(CI);
2397  return commonCastTransforms(CI);
2398 }
2399 
2401  // If the destination pointer element type is not the same as the source's
2402  // first do a bitcast to the destination type, and then the addrspacecast.
2403  // This allows the cast to be exposed to other transforms.
2404  Value *Src = CI.getOperand(0);
2405  PointerType *SrcTy = cast<PointerType>(Src->getType()->getScalarType());
2406  PointerType *DestTy = cast<PointerType>(CI.getType()->getScalarType());
2407 
2408  Type *DestElemTy = DestTy->getElementType();
2409  if (SrcTy->getElementType() != DestElemTy) {
2410  Type *MidTy = PointerType::get(DestElemTy, SrcTy->getAddressSpace());
2411  if (VectorType *VT = dyn_cast<VectorType>(CI.getType())) {
2412  // Handle vectors of pointers.
2413  MidTy = VectorType::get(MidTy, VT->getNumElements());
2414  }
2415 
2416  Value *NewBitCast = Builder.CreateBitCast(Src, MidTy);
2417  return new AddrSpaceCastInst(NewBitCast, CI.getType());
2418  }
2419 
2420  return commonPointerCastTransforms(CI);
2421 }
static BinaryOperator * CreateFMulFMF(Value *V1, Value *V2, BinaryOperator *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:205
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:725
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.
Definition: PatternMatch.h:909
void push_back(const T &Elt)
Definition: SmallVector.h:218
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:72
This class is the base class for the comparison instructions.
Definition: InstrTypes.h:675
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
static Type * getDoubleTy(LLVMContext &C)
Definition: Type.cpp:165
Type * getSrcTy() const
Return the source type, as a convenience.
Definition: InstrTypes.h:650
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:1557
ThreeOps_match< Cond, LHS, RHS, Instruction::Select > m_Select(const Cond &C, const LHS &L, const RHS &R)
Matches SelectInst.
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
BinaryOp_match< LHS, RHS, Instruction::Sub > m_Sub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:651
DiagnosticInfoOptimizationBase::Argument NV
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
BinaryOps getOpcode() const
Definition: InstrTypes.h:355
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
void setAlignment(unsigned Align)
This class represents zero extension of integer types.
Instruction * commonCastTransforms(CastInst &CI)
Implement the transforms common to all CastInst visitors.
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:648
class_match< Constant > m_Constant()
Match an arbitrary Constant and ignore it.
Definition: PatternMatch.h:91
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:617
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:755
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:714
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:811
F(f)
static CallInst * Create(Value *Func, ArrayRef< Value *> Args, ArrayRef< OperandBundleDef > Bundles=None, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
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:169
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:361
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1503
BinOpPred_match< LHS, RHS, is_logical_shift_op > m_LogicalShift(const LHS &L, const RHS &R)
Matches logical shift operations.
Definition: PatternMatch.h:917
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:268
Instruction * visitFPExt(CastInst &CI)
Instruction * FoldItoFPtoI(Instruction &FI)
unsigned countTrailingZeros() const
Count the number of trailing zero bits.
Definition: APInt.h:1626
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
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:1590
BinaryOp_match< LHS, RHS, Instruction::Xor > m_Xor(const LHS &L, const RHS &R)
Definition: PatternMatch.h:737
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:113
static bool hasStoreUsersOnly(CastInst &CI)
Check if all users of CI are StoreInsts.
static Type * getFloatTy(LLVMContext &C)
Definition: Type.cpp:164
This is the base class for all instructions that perform data casts.
Definition: InstrTypes.h:392
PointerType * getType() const
Overload to return most specific pointer type.
Definition: Instructions.h:97
&#39;undef&#39; values are things that do not have specified contents.
Definition: Constants.h:1275
static Constant * getLShr(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2264
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...
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
Definition: DerivedTypes.h:359
static Type * getPPC_FP128Ty(LLVMContext &C)
Definition: Type.cpp:170
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:1642
Value * CreateBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1641
static bool isMultipleOfTypeSize(unsigned Value, Type *Ty)
Instruction::CastOps getOpcode() const
Return the opcode of this CastInst.
Definition: InstrTypes.h:645
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
bool insert(const value_type &X)
Insert a new element into the SetVector.
Definition: SetVector.h:142
opStatus convert(const fltSemantics &ToSemantics, roundingMode RM, bool *losesInfo)
Definition: APFloat.cpp:4444
match_combine_or< LTy, RTy > m_CombineOr(const LTy &L, const RTy &R)
Combine two pattern matchers matching L || R.
Definition: PatternMatch.h:125
CastClass_match< OpTy, Instruction::ZExt > m_ZExt(const OpTy &Op)
Matches ZExt.
#define T
bool isUsedWithInAlloca() const
Return true if this alloca is used as an inalloca argument to a call.
Definition: Instructions.h:125
static bool isValidElementType(Type *ElemTy)
Return true if the specified type is valid as a element type.
Definition: Type.cpp:608
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:83
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:138
static APInt getBitsSetFrom(unsigned numBits, unsigned loBit)
Get a value with upper bits starting at loBit set.
Definition: APInt.h:624
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:126
An instruction for storing to memory.
Definition: Instructions.h:310
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:134
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:123
bool replaceAllDbgUsesWith(Instruction &From, Value &To, Instruction &DomPoint, DominatorTree &DT)
Point debug users of From to To or salvage them.
Definition: Local.cpp:1826
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:301
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:1021
This class represents a truncation of integer types.
Value * getOperand(unsigned i) const
Definition: User.h:170
Class to represent pointers.
Definition: DerivedTypes.h:467
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:304
const DataLayout & getDataLayout() const
static APInt getHighBitsSet(unsigned numBits, unsigned hiBitsSet)
Get a value with high bits set.
Definition: APInt.h:636
static Constant * getBitCast(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1750
an instruction for type-safe pointer arithmetic to access elements of arrays and structs ...
Definition: Instructions.h:843
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:63
#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:749
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:396
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:149
apint_match m_APInt(const APInt *&Res)
Match a ConstantInt or splatted ConstantVector, binding the specified pointer to the contained APInt...
Definition: PatternMatch.h:177
unsigned countPopulation() const
Count the number of bits set.
Definition: APInt.h:1652
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:731
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1179
CastClass_match< OpTy, Instruction::BitCast > m_BitCast(const OpTy &Op)
Matches BitCast.
This is an important base class in LLVM.
Definition: Constant.h:42
unsigned getNumContainedTypes() const
Return the number of types in the derived type.
Definition: Type.h:339
void setUsedWithInAlloca(bool V)
Specify whether this alloca is used to represent the arguments to a call.
Definition: Instructions.h:130
bool isPointerTy() const
True if this is an instance of PointerType.
Definition: Type.h:224
ConstantFP - Floating Point Values [float, double].
Definition: Constants.h:264
static unsigned getScalarSizeInBits(Type *Ty)
cst_pred_ty< is_all_ones > m_AllOnes()
Match an integer or vector with all bits set.
Definition: PatternMatch.h:306
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:499
BinaryOp_match< LHS, RHS, Instruction::Shl > m_Shl(const LHS &L, const RHS &R)
Definition: PatternMatch.h:743
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:685
Utility class for integer operators which may exhibit overflow - Add, Sub, Mul, and Shl...
Definition: Operator.h:67
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:495
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:75
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:322
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:1392
const Value * getArraySize() const
Get the number of elements allocated.
Definition: Instructions.h:93
size_t size() const
Definition: SmallVector.h:53
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:1564
deferredval_ty< Value > m_Deferred(Value *const &V)
A commutative-friendly version of m_Specific().
Definition: PatternMatch.h:512
Type * getAllocatedType() const
Return the type that is being allocated by the instruction.
Definition: Instructions.h:106
signed greater than
Definition: InstrTypes.h:712
const APFloat & getValueAPF() const
Definition: Constants.h:299
CastClass_match< OpTy, Instruction::SExt > m_SExt(const OpTy &Op)
Matches SExt.
static Type * getHalfTy(LLVMContext &C)
Definition: Type.cpp:163
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:240
static const fltSemantics & IEEEsingle() LLVM_READNONE
Definition: APFloat.cpp:120
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:298
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:84
static const fltSemantics & IEEEhalf() LLVM_READNONE
Definition: APFloat.cpp:117
SelectPatternFlavor Flavor
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:130
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:847
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:64
Value * CreateInsertElement(Value *Vec, Value *NewElt, Value *Idx, const Twine &Name="")
Definition: IRBuilder.h:1946
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:714
This class represents a cast from floating point to unsigned integer.
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:381
Instruction * visitZExt(ZExtInst &CI)
ConstantInt * getInt32(uint32_t C)
Get a constant 32-bit value.
Definition: IRBuilder.h:307
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:1614
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:621
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:652
unsigned getNumIncomingValues() const
Return the number of incoming edges.
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1287
static BinaryOperator * CreateFDivFMF(Value *V1, Value *V2, BinaryOperator *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:210
void setOperand(unsigned i, Value *Val)
Definition: User.h:175
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:133
unsigned getVectorNumElements() const
Definition: DerivedTypes.h:462
Class to represent vector types.
Definition: DerivedTypes.h:393
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:56
Class for arbitrary precision integers.
Definition: APInt.h:70
bool isPowerOf2() const
Check if this APInt&#39;s value is a power of two greater than zero.
Definition: APInt.h:464
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:400
bool hasNoSignedWrap() const
Test whether this operation is known to never undergo signed overflow, aka the nsw property...
Definition: Operator.h:96
const Value * getFalseValue() const
static CastInst * Create(Instruction::CastOps, Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Provides a way to construct any of the CastInst subclasses using an opcode instead of the subclass&#39;s ...
Predicate getPredicate() const
Return the predicate for this instruction.
Definition: InstrTypes.h:759
Instruction * visitTrunc(TruncInst &CI)
static Type * shrinkFPConstantVector(Value *V)
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:176
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:56
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:482
static bool isFNeg(const Value *V, bool IgnoreZeroSign=false)
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:224
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...
static BinaryOperator * CreateFNegFMF(Value *Op, BinaryOperator *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:220
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:323
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:1678
static GetElementPtrInst * CreateInBounds(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Create an "inbounds" getelementptr.
Definition: Instructions.h:903
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This class represents a truncation of floating point types.
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:115
LLVM Value Representation.
Definition: Value.h:73
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 VectorType * get(Type *ElementType, unsigned NumElements)
This static method is the primary way to construct an VectorType.
Definition: Type.cpp:593
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:81
Instruction * commonPointerCastTransforms(CastInst &CI)
Implement the transforms for cast of pointer (bitcast/ptrtoint)
Type * getElementType() const
Definition: DerivedTypes.h:360
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:413
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:99
unsigned countLeadingZeros() const
The APInt version of the countLeadingZeros functions in MathExtras.h.
Definition: APInt.h:1590
specific_intval m_SpecificInt(uint64_t V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:576
bool isBigEndian() const
Definition: DataLayout.h:222
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:2531
Instruction * visitPtrToInt(PtrToIntInst &CI)
static ExtractElementInst * Create(Value *Vec, Value *Idx, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
#define LLVM_DEBUG(X)
Definition: Debug.h:123
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:486
bool isNullValue() const
Determine if all bits are clear.
Definition: APInt.h:406
an instruction to allocate memory on the stack
Definition: Instructions.h:60
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:90