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  // Bail out on strange types. It is possible to handle some of these patterns
502  // even with non-power-of-2 sizes, but it is not a likely scenario.
503  Type *DestTy = Trunc.getType();
504  unsigned NarrowWidth = DestTy->getScalarSizeInBits();
505  if (!isPowerOf2_32(NarrowWidth))
506  return nullptr;
507 
508  // First, find an or'd pair of opposite shifts with the same shifted operand:
509  // trunc (or (lshr ShVal, ShAmt0), (shl ShVal, ShAmt1))
510  Value *Or0, *Or1;
511  if (!match(Trunc.getOperand(0), m_OneUse(m_Or(m_Value(Or0), m_Value(Or1)))))
512  return nullptr;
513 
514  Value *ShVal, *ShAmt0, *ShAmt1;
515  if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal), m_Value(ShAmt0)))) ||
516  !match(Or1, m_OneUse(m_LogicalShift(m_Specific(ShVal), m_Value(ShAmt1)))))
517  return nullptr;
518 
519  auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode();
520  auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode();
521  if (ShiftOpcode0 == ShiftOpcode1)
522  return nullptr;
523 
524  // Match the shift amount operands for a rotate pattern. This always matches
525  // a subtraction on the R operand.
526  auto matchShiftAmount = [](Value *L, Value *R, unsigned Width) -> Value * {
527  // The shift amounts may add up to the narrow bit width:
528  // (shl ShVal, L) | (lshr ShVal, Width - L)
529  if (match(R, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(L)))))
530  return L;
531 
532  // The shift amount may be masked with negation:
533  // (shl ShVal, (X & (Width - 1))) | (lshr ShVal, ((-X) & (Width - 1)))
534  Value *X;
535  unsigned Mask = Width - 1;
536  if (match(L, m_And(m_Value(X), m_SpecificInt(Mask))) &&
537  match(R, m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask))))
538  return X;
539 
540  // Same as above, but the shift amount may be extended after masking:
541  if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) &&
542  match(R, m_ZExt(m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask)))))
543  return X;
544 
545  return nullptr;
546  };
547 
548  Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, NarrowWidth);
549  bool SubIsOnLHS = false;
550  if (!ShAmt) {
551  ShAmt = matchShiftAmount(ShAmt1, ShAmt0, NarrowWidth);
552  SubIsOnLHS = true;
553  }
554  if (!ShAmt)
555  return nullptr;
556 
557  // The shifted value must have high zeros in the wide type. Typically, this
558  // will be a zext, but it could also be the result of an 'and' or 'shift'.
559  unsigned WideWidth = Trunc.getSrcTy()->getScalarSizeInBits();
560  APInt HiBitMask = APInt::getHighBitsSet(WideWidth, WideWidth - NarrowWidth);
561  if (!MaskedValueIsZero(ShVal, HiBitMask, 0, &Trunc))
562  return nullptr;
563 
564  // We have an unnecessarily wide rotate!
565  // trunc (or (lshr ShVal, ShAmt), (shl ShVal, BitWidth - ShAmt))
566  // Narrow it down to eliminate the zext/trunc:
567  // or (lshr trunc(ShVal), ShAmt0'), (shl trunc(ShVal), ShAmt1')
568  Value *NarrowShAmt = Builder.CreateTrunc(ShAmt, DestTy);
569  Value *NegShAmt = Builder.CreateNeg(NarrowShAmt);
570 
571  // Mask both shift amounts to ensure there's no UB from oversized shifts.
572  Constant *MaskC = ConstantInt::get(DestTy, NarrowWidth - 1);
573  Value *MaskedShAmt = Builder.CreateAnd(NarrowShAmt, MaskC);
574  Value *MaskedNegShAmt = Builder.CreateAnd(NegShAmt, MaskC);
575 
576  // Truncate the original value and use narrow ops.
577  Value *X = Builder.CreateTrunc(ShVal, DestTy);
578  Value *NarrowShAmt0 = SubIsOnLHS ? MaskedNegShAmt : MaskedShAmt;
579  Value *NarrowShAmt1 = SubIsOnLHS ? MaskedShAmt : MaskedNegShAmt;
580  Value *NarrowSh0 = Builder.CreateBinOp(ShiftOpcode0, X, NarrowShAmt0);
581  Value *NarrowSh1 = Builder.CreateBinOp(ShiftOpcode1, X, NarrowShAmt1);
582  return BinaryOperator::CreateOr(NarrowSh0, NarrowSh1);
583 }
584 
585 /// Try to narrow the width of math or bitwise logic instructions by pulling a
586 /// truncate ahead of binary operators.
587 /// TODO: Transforms for truncated shifts should be moved into here.
588 Instruction *InstCombiner::narrowBinOp(TruncInst &Trunc) {
589  Type *SrcTy = Trunc.getSrcTy();
590  Type *DestTy = Trunc.getType();
591  if (!isa<VectorType>(SrcTy) && !shouldChangeType(SrcTy, DestTy))
592  return nullptr;
593 
594  BinaryOperator *BinOp;
595  if (!match(Trunc.getOperand(0), m_OneUse(m_BinOp(BinOp))))
596  return nullptr;
597 
598  Value *BinOp0 = BinOp->getOperand(0);
599  Value *BinOp1 = BinOp->getOperand(1);
600  switch (BinOp->getOpcode()) {
601  case Instruction::And:
602  case Instruction::Or:
603  case Instruction::Xor:
604  case Instruction::Add:
605  case Instruction::Sub:
606  case Instruction::Mul: {
607  Constant *C;
608  if (match(BinOp0, m_Constant(C))) {
609  // trunc (binop C, X) --> binop (trunc C', X)
610  Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
611  Value *TruncX = Builder.CreateTrunc(BinOp1, DestTy);
612  return BinaryOperator::Create(BinOp->getOpcode(), NarrowC, TruncX);
613  }
614  if (match(BinOp1, m_Constant(C))) {
615  // trunc (binop X, C) --> binop (trunc X, C')
616  Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
617  Value *TruncX = Builder.CreateTrunc(BinOp0, DestTy);
618  return BinaryOperator::Create(BinOp->getOpcode(), TruncX, NarrowC);
619  }
620  Value *X;
621  if (match(BinOp0, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) {
622  // trunc (binop (ext X), Y) --> binop X, (trunc Y)
623  Value *NarrowOp1 = Builder.CreateTrunc(BinOp1, DestTy);
624  return BinaryOperator::Create(BinOp->getOpcode(), X, NarrowOp1);
625  }
626  if (match(BinOp1, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) {
627  // trunc (binop Y, (ext X)) --> binop (trunc Y), X
628  Value *NarrowOp0 = Builder.CreateTrunc(BinOp0, DestTy);
629  return BinaryOperator::Create(BinOp->getOpcode(), NarrowOp0, X);
630  }
631  break;
632  }
633 
634  default: break;
635  }
636 
637  if (Instruction *NarrowOr = narrowRotate(Trunc))
638  return NarrowOr;
639 
640  return nullptr;
641 }
642 
643 /// Try to narrow the width of a splat shuffle. This could be generalized to any
644 /// shuffle with a constant operand, but we limit the transform to avoid
645 /// creating a shuffle type that targets may not be able to lower effectively.
647  InstCombiner::BuilderTy &Builder) {
648  auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
649  if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) &&
650  Shuf->getMask()->getSplatValue() &&
651  Shuf->getType() == Shuf->getOperand(0)->getType()) {
652  // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
653  Constant *NarrowUndef = UndefValue::get(Trunc.getType());
654  Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
655  return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getMask());
656  }
657 
658  return nullptr;
659 }
660 
661 /// Try to narrow the width of an insert element. This could be generalized for
662 /// any vector constant, but we limit the transform to insertion into undef to
663 /// avoid potential backend problems from unsupported insertion widths. This
664 /// could also be extended to handle the case of inserting a scalar constant
665 /// into a vector variable.
667  InstCombiner::BuilderTy &Builder) {
668  Instruction::CastOps Opcode = Trunc.getOpcode();
669  assert((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) &&
670  "Unexpected instruction for shrinking");
671 
672  auto *InsElt = dyn_cast<InsertElementInst>(Trunc.getOperand(0));
673  if (!InsElt || !InsElt->hasOneUse())
674  return nullptr;
675 
676  Type *DestTy = Trunc.getType();
677  Type *DestScalarTy = DestTy->getScalarType();
678  Value *VecOp = InsElt->getOperand(0);
679  Value *ScalarOp = InsElt->getOperand(1);
680  Value *Index = InsElt->getOperand(2);
681 
682  if (isa<UndefValue>(VecOp)) {
683  // trunc (inselt undef, X, Index) --> inselt undef, (trunc X), Index
684  // fptrunc (inselt undef, X, Index) --> inselt undef, (fptrunc X), Index
685  UndefValue *NarrowUndef = UndefValue::get(DestTy);
686  Value *NarrowOp = Builder.CreateCast(Opcode, ScalarOp, DestScalarTy);
687  return InsertElementInst::Create(NarrowUndef, NarrowOp, Index);
688  }
689 
690  return nullptr;
691 }
692 
694  if (Instruction *Result = commonCastTransforms(CI))
695  return Result;
696 
697  Value *Src = CI.getOperand(0);
698  Type *DestTy = CI.getType(), *SrcTy = Src->getType();
699 
700  // Attempt to truncate the entire input expression tree to the destination
701  // type. Only do this if the dest type is a simple type, don't convert the
702  // expression tree to something weird like i93 unless the source is also
703  // strange.
704  if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) &&
705  canEvaluateTruncated(Src, DestTy, *this, &CI)) {
706 
707  // If this cast is a truncate, evaluting in a different type always
708  // eliminates the cast, so it is always a win.
709  LLVM_DEBUG(
710  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
711  " to avoid cast: "
712  << CI << '\n');
713  Value *Res = EvaluateInDifferentType(Src, DestTy, false);
714  assert(Res->getType() == DestTy);
715  return replaceInstUsesWith(CI, Res);
716  }
717 
718  // Test if the trunc is the user of a select which is part of a
719  // minimum or maximum operation. If so, don't do any more simplification.
720  // Even simplifying demanded bits can break the canonical form of a
721  // min/max.
722  Value *LHS, *RHS;
723  if (SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0)))
724  if (matchSelectPattern(SI, LHS, RHS).Flavor != SPF_UNKNOWN)
725  return nullptr;
726 
727  // See if we can simplify any instructions used by the input whose sole
728  // purpose is to compute bits we don't care about.
729  if (SimplifyDemandedInstructionBits(CI))
730  return &CI;
731 
732  if (DestTy->getScalarSizeInBits() == 1) {
733  Value *Zero = Constant::getNullValue(Src->getType());
734  if (DestTy->isIntegerTy()) {
735  // Canonicalize trunc x to i1 -> icmp ne (and x, 1), 0 (scalar only).
736  // TODO: We canonicalize to more instructions here because we are probably
737  // lacking equivalent analysis for trunc relative to icmp. There may also
738  // be codegen concerns. If those trunc limitations were removed, we could
739  // remove this transform.
740  Value *And = Builder.CreateAnd(Src, ConstantInt::get(SrcTy, 1));
741  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
742  }
743 
744  // For vectors, we do not canonicalize all truncs to icmp, so optimize
745  // patterns that would be covered within visitICmpInst.
746  Value *X;
747  const APInt *C;
748  if (match(Src, m_OneUse(m_LShr(m_Value(X), m_APInt(C))))) {
749  // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0
750  APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C);
751  Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC));
752  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
753  }
754  if (match(Src, m_OneUse(m_c_Or(m_LShr(m_Value(X), m_APInt(C)),
755  m_Deferred(X))))) {
756  // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0
757  APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C) | 1;
758  Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC));
759  return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
760  }
761  }
762 
763  // FIXME: Maybe combine the next two transforms to handle the no cast case
764  // more efficiently. Support vector types. Cleanup code by using m_OneUse.
765 
766  // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
767  Value *A = nullptr; ConstantInt *Cst = nullptr;
768  if (Src->hasOneUse() &&
769  match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
770  // We have three types to worry about here, the type of A, the source of
771  // the truncate (MidSize), and the destination of the truncate. We know that
772  // ASize < MidSize and MidSize > ResultSize, but don't know the relation
773  // between ASize and ResultSize.
774  unsigned ASize = A->getType()->getPrimitiveSizeInBits();
775 
776  // If the shift amount is larger than the size of A, then the result is
777  // known to be zero because all the input bits got shifted out.
778  if (Cst->getZExtValue() >= ASize)
779  return replaceInstUsesWith(CI, Constant::getNullValue(DestTy));
780 
781  // Since we're doing an lshr and a zero extend, and know that the shift
782  // amount is smaller than ASize, it is always safe to do the shift in A's
783  // type, then zero extend or truncate to the result.
784  Value *Shift = Builder.CreateLShr(A, Cst->getZExtValue());
785  Shift->takeName(Src);
786  return CastInst::CreateIntegerCast(Shift, DestTy, false);
787  }
788 
789  // FIXME: We should canonicalize to zext/trunc and remove this transform.
790  // Transform trunc(lshr (sext A), Cst) to ashr A, Cst to eliminate type
791  // conversion.
792  // It works because bits coming from sign extension have the same value as
793  // the sign bit of the original value; performing ashr instead of lshr
794  // generates bits of the same value as the sign bit.
795  if (Src->hasOneUse() &&
796  match(Src, m_LShr(m_SExt(m_Value(A)), m_ConstantInt(Cst)))) {
797  Value *SExt = cast<Instruction>(Src)->getOperand(0);
798  const unsigned SExtSize = SExt->getType()->getPrimitiveSizeInBits();
799  const unsigned ASize = A->getType()->getPrimitiveSizeInBits();
800  const unsigned CISize = CI.getType()->getPrimitiveSizeInBits();
801  const unsigned MaxAmt = SExtSize - std::max(CISize, ASize);
802  unsigned ShiftAmt = Cst->getZExtValue();
803 
804  // This optimization can be only performed when zero bits generated by
805  // the original lshr aren't pulled into the value after truncation, so we
806  // can only shift by values no larger than the number of extension bits.
807  // FIXME: Instead of bailing when the shift is too large, use and to clear
808  // the extra bits.
809  if (ShiftAmt <= MaxAmt) {
810  if (CISize == ASize)
811  return BinaryOperator::CreateAShr(A, ConstantInt::get(CI.getType(),
812  std::min(ShiftAmt, ASize - 1)));
813  if (SExt->hasOneUse()) {
814  Value *Shift = Builder.CreateAShr(A, std::min(ShiftAmt, ASize - 1));
815  Shift->takeName(Src);
816  return CastInst::CreateIntegerCast(Shift, CI.getType(), true);
817  }
818  }
819  }
820 
821  if (Instruction *I = narrowBinOp(CI))
822  return I;
823 
824  if (Instruction *I = shrinkSplatShuffle(CI, Builder))
825  return I;
826 
827  if (Instruction *I = shrinkInsertElt(CI, Builder))
828  return I;
829 
830  if (Src->hasOneUse() && isa<IntegerType>(SrcTy) &&
831  shouldChangeType(SrcTy, DestTy)) {
832  // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
833  // dest type is native and cst < dest size.
834  if (match(Src, m_Shl(m_Value(A), m_ConstantInt(Cst))) &&
835  !match(A, m_Shr(m_Value(), m_Constant()))) {
836  // Skip shifts of shift by constants. It undoes a combine in
837  // FoldShiftByConstant and is the extend in reg pattern.
838  const unsigned DestSize = DestTy->getScalarSizeInBits();
839  if (Cst->getValue().ult(DestSize)) {
840  Value *NewTrunc = Builder.CreateTrunc(A, DestTy, A->getName() + ".tr");
841 
842  return BinaryOperator::Create(
843  Instruction::Shl, NewTrunc,
844  ConstantInt::get(DestTy, Cst->getValue().trunc(DestSize)));
845  }
846  }
847  }
848 
849  if (Instruction *I = foldVecTruncToExtElt(CI, *this))
850  return I;
851 
852  return nullptr;
853 }
854 
855 Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, ZExtInst &CI,
856  bool DoTransform) {
857  // If we are just checking for a icmp eq of a single bit and zext'ing it
858  // to an integer, then shift the bit to the appropriate place and then
859  // cast to integer to avoid the comparison.
860  const APInt *Op1CV;
861  if (match(ICI->getOperand(1), m_APInt(Op1CV))) {
862 
863  // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
864  // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
865  if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isNullValue()) ||
866  (ICI->getPredicate() == ICmpInst::ICMP_SGT && Op1CV->isAllOnesValue())) {
867  if (!DoTransform) return ICI;
868 
869  Value *In = ICI->getOperand(0);
870  Value *Sh = ConstantInt::get(In->getType(),
871  In->getType()->getScalarSizeInBits() - 1);
872  In = Builder.CreateLShr(In, Sh, In->getName() + ".lobit");
873  if (In->getType() != CI.getType())
874  In = Builder.CreateIntCast(In, CI.getType(), false /*ZExt*/);
875 
876  if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
877  Constant *One = ConstantInt::get(In->getType(), 1);
878  In = Builder.CreateXor(In, One, In->getName() + ".not");
879  }
880 
881  return replaceInstUsesWith(CI, In);
882  }
883 
884  // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
885  // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
886  // zext (X == 1) to i32 --> X iff X has only the low bit set.
887  // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
888  // zext (X != 0) to i32 --> X iff X has only the low bit set.
889  // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
890  // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
891  // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
892  if ((Op1CV->isNullValue() || Op1CV->isPowerOf2()) &&
893  // This only works for EQ and NE
894  ICI->isEquality()) {
895  // If Op1C some other power of two, convert:
896  KnownBits Known = computeKnownBits(ICI->getOperand(0), 0, &CI);
897 
898  APInt KnownZeroMask(~Known.Zero);
899  if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
900  if (!DoTransform) return ICI;
901 
902  bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
903  if (!Op1CV->isNullValue() && (*Op1CV != KnownZeroMask)) {
904  // (X&4) == 2 --> false
905  // (X&4) != 2 --> true
906  Constant *Res = ConstantInt::get(CI.getType(), isNE);
907  return replaceInstUsesWith(CI, Res);
908  }
909 
910  uint32_t ShAmt = KnownZeroMask.logBase2();
911  Value *In = ICI->getOperand(0);
912  if (ShAmt) {
913  // Perform a logical shr by shiftamt.
914  // Insert the shift to put the result in the low bit.
915  In = Builder.CreateLShr(In, ConstantInt::get(In->getType(), ShAmt),
916  In->getName() + ".lobit");
917  }
918 
919  if (!Op1CV->isNullValue() == isNE) { // Toggle the low bit.
920  Constant *One = ConstantInt::get(In->getType(), 1);
921  In = Builder.CreateXor(In, One);
922  }
923 
924  if (CI.getType() == In->getType())
925  return replaceInstUsesWith(CI, In);
926 
927  Value *IntCast = Builder.CreateIntCast(In, CI.getType(), false);
928  return replaceInstUsesWith(CI, IntCast);
929  }
930  }
931  }
932 
933  // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
934  // It is also profitable to transform icmp eq into not(xor(A, B)) because that
935  // may lead to additional simplifications.
936  if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
937  if (IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
938  Value *LHS = ICI->getOperand(0);
939  Value *RHS = ICI->getOperand(1);
940 
941  KnownBits KnownLHS = computeKnownBits(LHS, 0, &CI);
942  KnownBits KnownRHS = computeKnownBits(RHS, 0, &CI);
943 
944  if (KnownLHS.Zero == KnownRHS.Zero && KnownLHS.One == KnownRHS.One) {
945  APInt KnownBits = KnownLHS.Zero | KnownLHS.One;
946  APInt UnknownBit = ~KnownBits;
947  if (UnknownBit.countPopulation() == 1) {
948  if (!DoTransform) return ICI;
949 
950  Value *Result = Builder.CreateXor(LHS, RHS);
951 
952  // Mask off any bits that are set and won't be shifted away.
953  if (KnownLHS.One.uge(UnknownBit))
954  Result = Builder.CreateAnd(Result,
955  ConstantInt::get(ITy, UnknownBit));
956 
957  // Shift the bit we're testing down to the lsb.
958  Result = Builder.CreateLShr(
959  Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
960 
961  if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
962  Result = Builder.CreateXor(Result, ConstantInt::get(ITy, 1));
963  Result->takeName(ICI);
964  return replaceInstUsesWith(CI, Result);
965  }
966  }
967  }
968  }
969 
970  return nullptr;
971 }
972 
973 /// Determine if the specified value can be computed in the specified wider type
974 /// and produce the same low bits. If not, return false.
975 ///
976 /// If this function returns true, it can also return a non-zero number of bits
977 /// (in BitsToClear) which indicates that the value it computes is correct for
978 /// the zero extend, but that the additional BitsToClear bits need to be zero'd
979 /// out. For example, to promote something like:
980 ///
981 /// %B = trunc i64 %A to i32
982 /// %C = lshr i32 %B, 8
983 /// %E = zext i32 %C to i64
984 ///
985 /// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
986 /// set to 8 to indicate that the promoted value needs to have bits 24-31
987 /// cleared in addition to bits 32-63. Since an 'and' will be generated to
988 /// clear the top bits anyway, doing this has no extra cost.
989 ///
990 /// This function works on both vectors and scalars.
991 static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear,
992  InstCombiner &IC, Instruction *CxtI) {
993  BitsToClear = 0;
994  if (canAlwaysEvaluateInType(V, Ty))
995  return true;
996  if (canNotEvaluateInType(V, Ty))
997  return false;
998 
999  auto *I = cast<Instruction>(V);
1000  unsigned Tmp;
1001  switch (I->getOpcode()) {
1002  case Instruction::ZExt: // zext(zext(x)) -> zext(x).
1003  case Instruction::SExt: // zext(sext(x)) -> sext(x).
1004  case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
1005  return true;
1006  case Instruction::And:
1007  case Instruction::Or:
1008  case Instruction::Xor:
1009  case Instruction::Add:
1010  case Instruction::Sub:
1011  case Instruction::Mul:
1012  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI) ||
1013  !canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI))
1014  return false;
1015  // These can all be promoted if neither operand has 'bits to clear'.
1016  if (BitsToClear == 0 && Tmp == 0)
1017  return true;
1018 
1019  // If the operation is an AND/OR/XOR and the bits to clear are zero in the
1020  // other side, BitsToClear is ok.
1021  if (Tmp == 0 && I->isBitwiseLogicOp()) {
1022  // We use MaskedValueIsZero here for generality, but the case we care
1023  // about the most is constant RHS.
1024  unsigned VSize = V->getType()->getScalarSizeInBits();
1025  if (IC.MaskedValueIsZero(I->getOperand(1),
1026  APInt::getHighBitsSet(VSize, BitsToClear),
1027  0, CxtI)) {
1028  // If this is an And instruction and all of the BitsToClear are
1029  // known to be zero we can reset BitsToClear.
1030  if (I->getOpcode() == Instruction::And)
1031  BitsToClear = 0;
1032  return true;
1033  }
1034  }
1035 
1036  // Otherwise, we don't know how to analyze this BitsToClear case yet.
1037  return false;
1038 
1039  case Instruction::Shl: {
1040  // We can promote shl(x, cst) if we can promote x. Since shl overwrites the
1041  // upper bits we can reduce BitsToClear by the shift amount.
1042  const APInt *Amt;
1043  if (match(I->getOperand(1), m_APInt(Amt))) {
1044  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
1045  return false;
1046  uint64_t ShiftAmt = Amt->getZExtValue();
1047  BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
1048  return true;
1049  }
1050  return false;
1051  }
1052  case Instruction::LShr: {
1053  // We can promote lshr(x, cst) if we can promote x. This requires the
1054  // ultimate 'and' to clear out the high zero bits we're clearing out though.
1055  const APInt *Amt;
1056  if (match(I->getOperand(1), m_APInt(Amt))) {
1057  if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
1058  return false;
1059  BitsToClear += Amt->getZExtValue();
1060  if (BitsToClear > V->getType()->getScalarSizeInBits())
1061  BitsToClear = V->getType()->getScalarSizeInBits();
1062  return true;
1063  }
1064  // Cannot promote variable LSHR.
1065  return false;
1066  }
1067  case Instruction::Select:
1068  if (!canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI) ||
1069  !canEvaluateZExtd(I->getOperand(2), Ty, BitsToClear, IC, CxtI) ||
1070  // TODO: If important, we could handle the case when the BitsToClear are
1071  // known zero in the disagreeing side.
1072  Tmp != BitsToClear)
1073  return false;
1074  return true;
1075 
1076  case Instruction::PHI: {
1077  // We can change a phi if we can change all operands. Note that we never
1078  // get into trouble with cyclic PHIs here because we only consider
1079  // instructions with a single use.
1080  PHINode *PN = cast<PHINode>(I);
1081  if (!canEvaluateZExtd(PN->getIncomingValue(0), Ty, BitsToClear, IC, CxtI))
1082  return false;
1083  for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
1084  if (!canEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp, IC, CxtI) ||
1085  // TODO: If important, we could handle the case when the BitsToClear
1086  // are known zero in the disagreeing input.
1087  Tmp != BitsToClear)
1088  return false;
1089  return true;
1090  }
1091  default:
1092  // TODO: Can handle more cases here.
1093  return false;
1094  }
1095 }
1096 
1098  // If this zero extend is only used by a truncate, let the truncate be
1099  // eliminated before we try to optimize this zext.
1100  if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
1101  return nullptr;
1102 
1103  // If one of the common conversion will work, do it.
1104  if (Instruction *Result = commonCastTransforms(CI))
1105  return Result;
1106 
1107  Value *Src = CI.getOperand(0);
1108  Type *SrcTy = Src->getType(), *DestTy = CI.getType();
1109 
1110  // Attempt to extend the entire input expression tree to the destination
1111  // type. Only do this if the dest type is a simple type, don't convert the
1112  // expression tree to something weird like i93 unless the source is also
1113  // strange.
1114  unsigned BitsToClear;
1115  if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) &&
1116  canEvaluateZExtd(Src, DestTy, BitsToClear, *this, &CI)) {
1117  assert(BitsToClear <= SrcTy->getScalarSizeInBits() &&
1118  "Can't clear more bits than in SrcTy");
1119 
1120  // Okay, we can transform this! Insert the new expression now.
1121  LLVM_DEBUG(
1122  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1123  " to avoid zero extend: "
1124  << CI << '\n');
1125  Value *Res = EvaluateInDifferentType(Src, DestTy, false);
1126  assert(Res->getType() == DestTy);
1127 
1128  // Preserve debug values referring to Src if the zext is its last use.
1129  if (auto *SrcOp = dyn_cast<Instruction>(Src))
1130  if (SrcOp->hasOneUse())
1131  replaceAllDbgUsesWith(*SrcOp, *Res, CI, DT);
1132 
1133  uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear;
1134  uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1135 
1136  // If the high bits are already filled with zeros, just replace this
1137  // cast with the result.
1138  if (MaskedValueIsZero(Res,
1139  APInt::getHighBitsSet(DestBitSize,
1140  DestBitSize-SrcBitsKept),
1141  0, &CI))
1142  return replaceInstUsesWith(CI, Res);
1143 
1144  // We need to emit an AND to clear the high bits.
1145  Constant *C = ConstantInt::get(Res->getType(),
1146  APInt::getLowBitsSet(DestBitSize, SrcBitsKept));
1147  return BinaryOperator::CreateAnd(Res, C);
1148  }
1149 
1150  // If this is a TRUNC followed by a ZEXT then we are dealing with integral
1151  // types and if the sizes are just right we can convert this into a logical
1152  // 'and' which will be much cheaper than the pair of casts.
1153  if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
1154  // TODO: Subsume this into EvaluateInDifferentType.
1155 
1156  // Get the sizes of the types involved. We know that the intermediate type
1157  // will be smaller than A or C, but don't know the relation between A and C.
1158  Value *A = CSrc->getOperand(0);
1159  unsigned SrcSize = A->getType()->getScalarSizeInBits();
1160  unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
1161  unsigned DstSize = CI.getType()->getScalarSizeInBits();
1162  // If we're actually extending zero bits, then if
1163  // SrcSize < DstSize: zext(a & mask)
1164  // SrcSize == DstSize: a & mask
1165  // SrcSize > DstSize: trunc(a) & mask
1166  if (SrcSize < DstSize) {
1167  APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
1168  Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
1169  Value *And = Builder.CreateAnd(A, AndConst, CSrc->getName() + ".mask");
1170  return new ZExtInst(And, CI.getType());
1171  }
1172 
1173  if (SrcSize == DstSize) {
1174  APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
1175  return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
1176  AndValue));
1177  }
1178  if (SrcSize > DstSize) {
1179  Value *Trunc = Builder.CreateTrunc(A, CI.getType());
1180  APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
1181  return BinaryOperator::CreateAnd(Trunc,
1182  ConstantInt::get(Trunc->getType(),
1183  AndValue));
1184  }
1185  }
1186 
1187  if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1188  return transformZExtICmp(ICI, CI);
1189 
1190  BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
1191  if (SrcI && SrcI->getOpcode() == Instruction::Or) {
1192  // zext (or icmp, icmp) -> or (zext icmp), (zext icmp) if at least one
1193  // of the (zext icmp) can be eliminated. If so, immediately perform the
1194  // according elimination.
1195  ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
1196  ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
1197  if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
1198  (transformZExtICmp(LHS, CI, false) ||
1199  transformZExtICmp(RHS, CI, false))) {
1200  // zext (or icmp, icmp) -> or (zext icmp), (zext icmp)
1201  Value *LCast = Builder.CreateZExt(LHS, CI.getType(), LHS->getName());
1202  Value *RCast = Builder.CreateZExt(RHS, CI.getType(), RHS->getName());
1203  BinaryOperator *Or = BinaryOperator::Create(Instruction::Or, LCast, RCast);
1204 
1205  // Perform the elimination.
1206  if (auto *LZExt = dyn_cast<ZExtInst>(LCast))
1207  transformZExtICmp(LHS, *LZExt);
1208  if (auto *RZExt = dyn_cast<ZExtInst>(RCast))
1209  transformZExtICmp(RHS, *RZExt);
1210 
1211  return Or;
1212  }
1213  }
1214 
1215  // zext(trunc(X) & C) -> (X & zext(C)).
1216  Constant *C;
1217  Value *X;
1218  if (SrcI &&
1219  match(SrcI, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) &&
1220  X->getType() == CI.getType())
1221  return BinaryOperator::CreateAnd(X, ConstantExpr::getZExt(C, CI.getType()));
1222 
1223  // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
1224  Value *And;
1225  if (SrcI && match(SrcI, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
1226  match(And, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Specific(C)))) &&
1227  X->getType() == CI.getType()) {
1228  Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
1229  return BinaryOperator::CreateXor(Builder.CreateAnd(X, ZC), ZC);
1230  }
1231 
1232  return nullptr;
1233 }
1234 
1235 /// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
1236 Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) {
1237  Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1);
1238  ICmpInst::Predicate Pred = ICI->getPredicate();
1239 
1240  // Don't bother if Op1 isn't of vector or integer type.
1241  if (!Op1->getType()->isIntOrIntVectorTy())
1242  return nullptr;
1243 
1244  if ((Pred == ICmpInst::ICMP_SLT && match(Op1, m_ZeroInt())) ||
1245  (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))) {
1246  // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if negative
1247  // (x >s -1) ? -1 : 0 -> not (ashr x, 31) -> all ones if positive
1248  Value *Sh = ConstantInt::get(Op0->getType(),
1249  Op0->getType()->getScalarSizeInBits() - 1);
1250  Value *In = Builder.CreateAShr(Op0, Sh, Op0->getName() + ".lobit");
1251  if (In->getType() != CI.getType())
1252  In = Builder.CreateIntCast(In, CI.getType(), true /*SExt*/);
1253 
1254  if (Pred == ICmpInst::ICMP_SGT)
1255  In = Builder.CreateNot(In, In->getName() + ".not");
1256  return replaceInstUsesWith(CI, In);
1257  }
1258 
1259  if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
1260  // If we know that only one bit of the LHS of the icmp can be set and we
1261  // have an equality comparison with zero or a power of 2, we can transform
1262  // the icmp and sext into bitwise/integer operations.
1263  if (ICI->hasOneUse() &&
1264  ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
1265  KnownBits Known = computeKnownBits(Op0, 0, &CI);
1266 
1267  APInt KnownZeroMask(~Known.Zero);
1268  if (KnownZeroMask.isPowerOf2()) {
1269  Value *In = ICI->getOperand(0);
1270 
1271  // If the icmp tests for a known zero bit we can constant fold it.
1272  if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
1273  Value *V = Pred == ICmpInst::ICMP_NE ?
1276  return replaceInstUsesWith(CI, V);
1277  }
1278 
1279  if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
1280  // sext ((x & 2^n) == 0) -> (x >> n) - 1
1281  // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
1282  unsigned ShiftAmt = KnownZeroMask.countTrailingZeros();
1283  // Perform a right shift to place the desired bit in the LSB.
1284  if (ShiftAmt)
1285  In = Builder.CreateLShr(In,
1286  ConstantInt::get(In->getType(), ShiftAmt));
1287 
1288  // At this point "In" is either 1 or 0. Subtract 1 to turn
1289  // {1, 0} -> {0, -1}.
1290  In = Builder.CreateAdd(In,
1292  "sext");
1293  } else {
1294  // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
1295  // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
1296  unsigned ShiftAmt = KnownZeroMask.countLeadingZeros();
1297  // Perform a left shift to place the desired bit in the MSB.
1298  if (ShiftAmt)
1299  In = Builder.CreateShl(In,
1300  ConstantInt::get(In->getType(), ShiftAmt));
1301 
1302  // Distribute the bit over the whole bit width.
1303  In = Builder.CreateAShr(In, ConstantInt::get(In->getType(),
1304  KnownZeroMask.getBitWidth() - 1), "sext");
1305  }
1306 
1307  if (CI.getType() == In->getType())
1308  return replaceInstUsesWith(CI, In);
1309  return CastInst::CreateIntegerCast(In, CI.getType(), true/*SExt*/);
1310  }
1311  }
1312  }
1313 
1314  return nullptr;
1315 }
1316 
1317 /// Return true if we can take the specified value and return it as type Ty
1318 /// without inserting any new casts and without changing the value of the common
1319 /// low bits. This is used by code that tries to promote integer operations to
1320 /// a wider types will allow us to eliminate the extension.
1321 ///
1322 /// This function works on both vectors and scalars.
1323 ///
1324 static bool canEvaluateSExtd(Value *V, Type *Ty) {
1326  "Can't sign extend type to a smaller type");
1327  if (canAlwaysEvaluateInType(V, Ty))
1328  return true;
1329  if (canNotEvaluateInType(V, Ty))
1330  return false;
1331 
1332  auto *I = cast<Instruction>(V);
1333  switch (I->getOpcode()) {
1334  case Instruction::SExt: // sext(sext(x)) -> sext(x)
1335  case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1336  case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1337  return true;
1338  case Instruction::And:
1339  case Instruction::Or:
1340  case Instruction::Xor:
1341  case Instruction::Add:
1342  case Instruction::Sub:
1343  case Instruction::Mul:
1344  // These operators can all arbitrarily be extended if their inputs can.
1345  return canEvaluateSExtd(I->getOperand(0), Ty) &&
1346  canEvaluateSExtd(I->getOperand(1), Ty);
1347 
1348  //case Instruction::Shl: TODO
1349  //case Instruction::LShr: TODO
1350 
1351  case Instruction::Select:
1352  return canEvaluateSExtd(I->getOperand(1), Ty) &&
1353  canEvaluateSExtd(I->getOperand(2), Ty);
1354 
1355  case Instruction::PHI: {
1356  // We can change a phi if we can change all operands. Note that we never
1357  // get into trouble with cyclic PHIs here because we only consider
1358  // instructions with a single use.
1359  PHINode *PN = cast<PHINode>(I);
1360  for (Value *IncValue : PN->incoming_values())
1361  if (!canEvaluateSExtd(IncValue, Ty)) return false;
1362  return true;
1363  }
1364  default:
1365  // TODO: Can handle more cases here.
1366  break;
1367  }
1368 
1369  return false;
1370 }
1371 
1373  // If this sign extend is only used by a truncate, let the truncate be
1374  // eliminated before we try to optimize this sext.
1375  if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
1376  return nullptr;
1377 
1378  if (Instruction *I = commonCastTransforms(CI))
1379  return I;
1380 
1381  Value *Src = CI.getOperand(0);
1382  Type *SrcTy = Src->getType(), *DestTy = CI.getType();
1383 
1384  // If we know that the value being extended is positive, we can use a zext
1385  // instead.
1386  KnownBits Known = computeKnownBits(Src, 0, &CI);
1387  if (Known.isNonNegative()) {
1388  Value *ZExt = Builder.CreateZExt(Src, DestTy);
1389  return replaceInstUsesWith(CI, ZExt);
1390  }
1391 
1392  // Attempt to extend the entire input expression tree to the destination
1393  // type. Only do this if the dest type is a simple type, don't convert the
1394  // expression tree to something weird like i93 unless the source is also
1395  // strange.
1396  if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) &&
1397  canEvaluateSExtd(Src, DestTy)) {
1398  // Okay, we can transform this! Insert the new expression now.
1399  LLVM_DEBUG(
1400  dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1401  " to avoid sign extend: "
1402  << CI << '\n');
1403  Value *Res = EvaluateInDifferentType(Src, DestTy, true);
1404  assert(Res->getType() == DestTy);
1405 
1406  uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
1407  uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1408 
1409  // If the high bits are already filled with sign bit, just replace this
1410  // cast with the result.
1411  if (ComputeNumSignBits(Res, 0, &CI) > DestBitSize - SrcBitSize)
1412  return replaceInstUsesWith(CI, Res);
1413 
1414  // We need to emit a shl + ashr to do the sign extend.
1415  Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
1416  return BinaryOperator::CreateAShr(Builder.CreateShl(Res, ShAmt, "sext"),
1417  ShAmt);
1418  }
1419 
1420  // If the input is a trunc from the destination type, then turn sext(trunc(x))
1421  // into shifts.
1422  Value *X;
1423  if (match(Src, m_OneUse(m_Trunc(m_Value(X)))) && X->getType() == DestTy) {
1424  // sext(trunc(X)) --> ashr(shl(X, C), C)
1425  unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
1426  unsigned DestBitSize = DestTy->getScalarSizeInBits();
1427  Constant *ShAmt = ConstantInt::get(DestTy, DestBitSize - SrcBitSize);
1428  return BinaryOperator::CreateAShr(Builder.CreateShl(X, ShAmt), ShAmt);
1429  }
1430 
1431  if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1432  return transformSExtICmp(ICI, CI);
1433 
1434  // If the input is a shl/ashr pair of a same constant, then this is a sign
1435  // extension from a smaller value. If we could trust arbitrary bitwidth
1436  // integers, we could turn this into a truncate to the smaller bit and then
1437  // use a sext for the whole extension. Since we don't, look deeper and check
1438  // for a truncate. If the source and dest are the same type, eliminate the
1439  // trunc and extend and just do shifts. For example, turn:
1440  // %a = trunc i32 %i to i8
1441  // %b = shl i8 %a, 6
1442  // %c = ashr i8 %b, 6
1443  // %d = sext i8 %c to i32
1444  // into:
1445  // %a = shl i32 %i, 30
1446  // %d = ashr i32 %a, 30
1447  Value *A = nullptr;
1448  // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
1449  ConstantInt *BA = nullptr, *CA = nullptr;
1450  if (match(Src, m_AShr(m_Shl(m_Trunc(m_Value(A)), m_ConstantInt(BA)),
1451  m_ConstantInt(CA))) &&
1452  BA == CA && A->getType() == CI.getType()) {
1453  unsigned MidSize = Src->getType()->getScalarSizeInBits();
1454  unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
1455  unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
1456  Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
1457  A = Builder.CreateShl(A, ShAmtV, CI.getName());
1458  return BinaryOperator::CreateAShr(A, ShAmtV);
1459  }
1460 
1461  return nullptr;
1462 }
1463 
1464 
1465 /// Return a Constant* for the specified floating-point constant if it fits
1466 /// in the specified FP type without changing its value.
1467 static bool fitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
1468  bool losesInfo;
1469  APFloat F = CFP->getValueAPF();
1470  (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
1471  return !losesInfo;
1472 }
1473 
1475  if (CFP->getType() == Type::getPPC_FP128Ty(CFP->getContext()))
1476  return nullptr; // No constant folding of this.
1477  // See if the value can be truncated to half and then reextended.
1478  if (fitsInFPType(CFP, APFloat::IEEEhalf()))
1479  return Type::getHalfTy(CFP->getContext());
1480  // See if the value can be truncated to float and then reextended.
1481  if (fitsInFPType(CFP, APFloat::IEEEsingle()))
1482  return Type::getFloatTy(CFP->getContext());
1483  if (CFP->getType()->isDoubleTy())
1484  return nullptr; // Won't shrink.
1485  if (fitsInFPType(CFP, APFloat::IEEEdouble()))
1486  return Type::getDoubleTy(CFP->getContext());
1487  // Don't try to shrink to various long double types.
1488  return nullptr;
1489 }
1490 
1491 // Determine if this is a vector of ConstantFPs and if so, return the minimal
1492 // type we can safely truncate all elements to.
1493 // TODO: Make these support undef elements.
1495  auto *CV = dyn_cast<Constant>(V);
1496  if (!CV || !CV->getType()->isVectorTy())
1497  return nullptr;
1498 
1499  Type *MinType = nullptr;
1500 
1501  unsigned NumElts = CV->getType()->getVectorNumElements();
1502  for (unsigned i = 0; i != NumElts; ++i) {
1503  auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i));
1504  if (!CFP)
1505  return nullptr;
1506 
1507  Type *T = shrinkFPConstant(CFP);
1508  if (!T)
1509  return nullptr;
1510 
1511  // If we haven't found a type yet or this type has a larger mantissa than
1512  // our previous type, this is our new minimal type.
1513  if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth())
1514  MinType = T;
1515  }
1516 
1517  // Make a vector type from the minimal type.
1518  return VectorType::get(MinType, NumElts);
1519 }
1520 
1521 /// Find the minimum FP type we can safely truncate to.
1523  if (auto *FPExt = dyn_cast<FPExtInst>(V))
1524  return FPExt->getOperand(0)->getType();
1525 
1526  // If this value is a constant, return the constant in the smallest FP type
1527  // that can accurately represent it. This allows us to turn
1528  // (float)((double)X+2.0) into x+2.0f.
1529  if (auto *CFP = dyn_cast<ConstantFP>(V))
1530  if (Type *T = shrinkFPConstant(CFP))
1531  return T;
1532 
1533  // Try to shrink a vector of FP constants.
1534  if (Type *T = shrinkFPConstantVector(V))
1535  return T;
1536 
1537  return V->getType();
1538 }
1539 
1541  if (Instruction *I = commonCastTransforms(FPT))
1542  return I;
1543 
1544  // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
1545  // simplify this expression to avoid one or more of the trunc/extend
1546  // operations if we can do so without changing the numerical results.
1547  //
1548  // The exact manner in which the widths of the operands interact to limit
1549  // what we can and cannot do safely varies from operation to operation, and
1550  // is explained below in the various case statements.
1551  Type *Ty = FPT.getType();
1553  if (OpI && OpI->hasOneUse()) {
1554  Type *LHSMinType = getMinimumFPType(OpI->getOperand(0));
1555  Type *RHSMinType = getMinimumFPType(OpI->getOperand(1));
1556  unsigned OpWidth = OpI->getType()->getFPMantissaWidth();
1557  unsigned LHSWidth = LHSMinType->getFPMantissaWidth();
1558  unsigned RHSWidth = RHSMinType->getFPMantissaWidth();
1559  unsigned SrcWidth = std::max(LHSWidth, RHSWidth);
1560  unsigned DstWidth = Ty->getFPMantissaWidth();
1561  switch (OpI->getOpcode()) {
1562  default: break;
1563  case Instruction::FAdd:
1564  case Instruction::FSub:
1565  // For addition and subtraction, the infinitely precise result can
1566  // essentially be arbitrarily wide; proving that double rounding
1567  // will not occur because the result of OpI is exact (as we will for
1568  // FMul, for example) is hopeless. However, we *can* nonetheless
1569  // frequently know that double rounding cannot occur (or that it is
1570  // innocuous) by taking advantage of the specific structure of
1571  // infinitely-precise results that admit double rounding.
1572  //
1573  // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
1574  // to represent both sources, we can guarantee that the double
1575  // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
1576  // "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
1577  // for proof of this fact).
1578  //
1579  // Note: Figueroa does not consider the case where DstFormat !=
1580  // SrcFormat. It's possible (likely even!) that this analysis
1581  // could be tightened for those cases, but they are rare (the main
1582  // case of interest here is (float)((double)float + float)).
1583  if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) {
1584  Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1585  Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
1586  Instruction *RI = BinaryOperator::Create(OpI->getOpcode(), LHS, RHS);
1587  RI->copyFastMathFlags(OpI);
1588  return RI;
1589  }
1590  break;
1591  case Instruction::FMul:
1592  // For multiplication, the infinitely precise result has at most
1593  // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
1594  // that such a value can be exactly represented, then no double
1595  // rounding can possibly occur; we can safely perform the operation
1596  // in the destination format if it can represent both sources.
1597  if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) {
1598  Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1599  Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
1600  return BinaryOperator::CreateFMulFMF(LHS, RHS, OpI);
1601  }
1602  break;
1603  case Instruction::FDiv:
1604  // For division, we use again use the bound from Figueroa's
1605  // dissertation. I am entirely certain that this bound can be
1606  // tightened in the unbalanced operand case by an analysis based on
1607  // the diophantine rational approximation bound, but the well-known
1608  // condition used here is a good conservative first pass.
1609  // TODO: Tighten bound via rigorous analysis of the unbalanced case.
1610  if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) {
1611  Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1612  Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
1613  return BinaryOperator::CreateFDivFMF(LHS, RHS, OpI);
1614  }
1615  break;
1616  case Instruction::FRem: {
1617  // Remainder is straightforward. Remainder is always exact, so the
1618  // type of OpI doesn't enter into things at all. We simply evaluate
1619  // in whichever source type is larger, then convert to the
1620  // destination type.
1621  if (SrcWidth == OpWidth)
1622  break;
1623  Value *LHS, *RHS;
1624  if (LHSWidth == SrcWidth) {
1625  LHS = Builder.CreateFPTrunc(OpI->getOperand(0), LHSMinType);
1626  RHS = Builder.CreateFPTrunc(OpI->getOperand(1), LHSMinType);
1627  } else {
1628  LHS = Builder.CreateFPTrunc(OpI->getOperand(0), RHSMinType);
1629  RHS = Builder.CreateFPTrunc(OpI->getOperand(1), RHSMinType);
1630  }
1631 
1632  Value *ExactResult = Builder.CreateFRemFMF(LHS, RHS, OpI);
1633  return CastInst::CreateFPCast(ExactResult, Ty);
1634  }
1635  }
1636 
1637  // (fptrunc (fneg x)) -> (fneg (fptrunc x))
1638  Value *X;
1639  if (match(OpI, m_FNeg(m_Value(X)))) {
1640  Value *InnerTrunc = Builder.CreateFPTrunc(X, Ty);
1641  return BinaryOperator::CreateFNegFMF(InnerTrunc, OpI);
1642  }
1643  }
1644 
1645  if (auto *II = dyn_cast<IntrinsicInst>(FPT.getOperand(0))) {
1646  switch (II->getIntrinsicID()) {
1647  default: break;
1648  case Intrinsic::ceil:
1649  case Intrinsic::fabs:
1650  case Intrinsic::floor:
1651  case Intrinsic::nearbyint:
1652  case Intrinsic::rint:
1653  case Intrinsic::round:
1654  case Intrinsic::trunc: {
1655  Value *Src = II->getArgOperand(0);
1656  if (!Src->hasOneUse())
1657  break;
1658 
1659  // Except for fabs, this transformation requires the input of the unary FP
1660  // operation to be itself an fpext from the type to which we're
1661  // truncating.
1662  if (II->getIntrinsicID() != Intrinsic::fabs) {
1663  FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Src);
1664  if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty)
1665  break;
1666  }
1667 
1668  // Do unary FP operation on smaller type.
1669  // (fptrunc (fabs x)) -> (fabs (fptrunc x))
1670  Value *InnerTrunc = Builder.CreateFPTrunc(Src, Ty);
1671  Function *Overload = Intrinsic::getDeclaration(FPT.getModule(),
1672  II->getIntrinsicID(), Ty);
1674  II->getOperandBundlesAsDefs(OpBundles);
1675  CallInst *NewCI = CallInst::Create(Overload, { InnerTrunc }, OpBundles,
1676  II->getName());
1677  NewCI->copyFastMathFlags(II);
1678  return NewCI;
1679  }
1680  }
1681  }
1682 
1683  if (Instruction *I = shrinkInsertElt(FPT, Builder))
1684  return I;
1685 
1686  return nullptr;
1687 }
1688 
1690  return commonCastTransforms(CI);
1691 }
1692 
1693 // fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
1694 // This is safe if the intermediate type has enough bits in its mantissa to
1695 // accurately represent all values of X. For example, this won't work with
1696 // i64 -> float -> i64.
1698  if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0)))
1699  return nullptr;
1700  Instruction *OpI = cast<Instruction>(FI.getOperand(0));
1701 
1702  Value *SrcI = OpI->getOperand(0);
1703  Type *FITy = FI.getType();
1704  Type *OpITy = OpI->getType();
1705  Type *SrcTy = SrcI->getType();
1706  bool IsInputSigned = isa<SIToFPInst>(OpI);
1707  bool IsOutputSigned = isa<FPToSIInst>(FI);
1708 
1709  // We can safely assume the conversion won't overflow the output range,
1710  // because (for example) (uint8_t)18293.f is undefined behavior.
1711 
1712  // Since we can assume the conversion won't overflow, our decision as to
1713  // whether the input will fit in the float should depend on the minimum
1714  // of the input range and output range.
1715 
1716  // This means this is also safe for a signed input and unsigned output, since
1717  // a negative input would lead to undefined behavior.
1718  int InputSize = (int)SrcTy->getScalarSizeInBits() - IsInputSigned;
1719  int OutputSize = (int)FITy->getScalarSizeInBits() - IsOutputSigned;
1720  int ActualSize = std::min(InputSize, OutputSize);
1721 
1722  if (ActualSize <= OpITy->getFPMantissaWidth()) {
1723  if (FITy->getScalarSizeInBits() > SrcTy->getScalarSizeInBits()) {
1724  if (IsInputSigned && IsOutputSigned)
1725  return new SExtInst(SrcI, FITy);
1726  return new ZExtInst(SrcI, FITy);
1727  }
1728  if (FITy->getScalarSizeInBits() < SrcTy->getScalarSizeInBits())
1729  return new TruncInst(SrcI, FITy);
1730  if (SrcTy == FITy)
1731  return replaceInstUsesWith(FI, SrcI);
1732  return new BitCastInst(SrcI, FITy);
1733  }
1734  return nullptr;
1735 }
1736 
1738  Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1739  if (!OpI)
1740  return commonCastTransforms(FI);
1741 
1742  if (Instruction *I = FoldItoFPtoI(FI))
1743  return I;
1744 
1745  return commonCastTransforms(FI);
1746 }
1747 
1749  Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1750  if (!OpI)
1751  return commonCastTransforms(FI);
1752 
1753  if (Instruction *I = FoldItoFPtoI(FI))
1754  return I;
1755 
1756  return commonCastTransforms(FI);
1757 }
1758 
1760  return commonCastTransforms(CI);
1761 }
1762 
1764  return commonCastTransforms(CI);
1765 }
1766 
1768  // If the source integer type is not the intptr_t type for this target, do a
1769  // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
1770  // cast to be exposed to other transforms.
1771  unsigned AS = CI.getAddressSpace();
1772  if (CI.getOperand(0)->getType()->getScalarSizeInBits() !=
1773  DL.getPointerSizeInBits(AS)) {
1774  Type *Ty = DL.getIntPtrType(CI.getContext(), AS);
1775  if (CI.getType()->isVectorTy()) // Handle vectors of pointers.
1776  Ty = VectorType::get(Ty, CI.getType()->getVectorNumElements());
1777 
1778  Value *P = Builder.CreateZExtOrTrunc(CI.getOperand(0), Ty);
1779  return new IntToPtrInst(P, CI.getType());
1780  }
1781 
1782  if (Instruction *I = commonCastTransforms(CI))
1783  return I;
1784 
1785  return nullptr;
1786 }
1787 
1788 /// Implement the transforms for cast of pointer (bitcast/ptrtoint)
1790  Value *Src = CI.getOperand(0);
1791 
1792  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
1793  // If casting the result of a getelementptr instruction with no offset, turn
1794  // this into a cast of the original pointer!
1795  if (GEP->hasAllZeroIndices() &&
1796  // If CI is an addrspacecast and GEP changes the poiner type, merging
1797  // GEP into CI would undo canonicalizing addrspacecast with different
1798  // pointer types, causing infinite loops.
1799  (!isa<AddrSpaceCastInst>(CI) ||
1800  GEP->getType() == GEP->getPointerOperandType())) {
1801  // Changing the cast operand is usually not a good idea but it is safe
1802  // here because the pointer operand is being replaced with another
1803  // pointer operand so the opcode doesn't need to change.
1804  Worklist.Add(GEP);
1805  CI.setOperand(0, GEP->getOperand(0));
1806  return &CI;
1807  }
1808  }
1809 
1810  return commonCastTransforms(CI);
1811 }
1812 
1814  // If the destination integer type is not the intptr_t type for this target,
1815  // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
1816  // to be exposed to other transforms.
1817 
1818  Type *Ty = CI.getType();
1819  unsigned AS = CI.getPointerAddressSpace();
1820 
1821  if (Ty->getScalarSizeInBits() == DL.getIndexSizeInBits(AS))
1822  return commonPointerCastTransforms(CI);
1823 
1824  Type *PtrTy = DL.getIntPtrType(CI.getContext(), AS);
1825  if (Ty->isVectorTy()) // Handle vectors of pointers.
1826  PtrTy = VectorType::get(PtrTy, Ty->getVectorNumElements());
1827 
1828  Value *P = Builder.CreatePtrToInt(CI.getOperand(0), PtrTy);
1829  return CastInst::CreateIntegerCast(P, Ty, /*isSigned=*/false);
1830 }
1831 
1832 /// This input value (which is known to have vector type) is being zero extended
1833 /// or truncated to the specified vector type.
1834 /// Try to replace it with a shuffle (and vector/vector bitcast) if possible.
1835 ///
1836 /// The source and destination vector types may have different element types.
1838  InstCombiner &IC) {
1839  // We can only do this optimization if the output is a multiple of the input
1840  // element size, or the input is a multiple of the output element size.
1841  // Convert the input type to have the same element type as the output.
1842  VectorType *SrcTy = cast<VectorType>(InVal->getType());
1843 
1844  if (SrcTy->getElementType() != DestTy->getElementType()) {
1845  // The input types don't need to be identical, but for now they must be the
1846  // same size. There is no specific reason we couldn't handle things like
1847  // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
1848  // there yet.
1849  if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
1851  return nullptr;
1852 
1853  SrcTy = VectorType::get(DestTy->getElementType(), SrcTy->getNumElements());
1854  InVal = IC.Builder.CreateBitCast(InVal, SrcTy);
1855  }
1856 
1857  // Now that the element types match, get the shuffle mask and RHS of the
1858  // shuffle to use, which depends on whether we're increasing or decreasing the
1859  // size of the input.
1860  SmallVector<uint32_t, 16> ShuffleMask;
1861  Value *V2;
1862 
1863  if (SrcTy->getNumElements() > DestTy->getNumElements()) {
1864  // If we're shrinking the number of elements, just shuffle in the low
1865  // elements from the input and use undef as the second shuffle input.
1866  V2 = UndefValue::get(SrcTy);
1867  for (unsigned i = 0, e = DestTy->getNumElements(); i != e; ++i)
1868  ShuffleMask.push_back(i);
1869 
1870  } else {
1871  // If we're increasing the number of elements, shuffle in all of the
1872  // elements from InVal and fill the rest of the result elements with zeros
1873  // from a constant zero.
1874  V2 = Constant::getNullValue(SrcTy);
1875  unsigned SrcElts = SrcTy->getNumElements();
1876  for (unsigned i = 0, e = SrcElts; i != e; ++i)
1877  ShuffleMask.push_back(i);
1878 
1879  // The excess elements reference the first element of the zero input.
1880  for (unsigned i = 0, e = DestTy->getNumElements()-SrcElts; i != e; ++i)
1881  ShuffleMask.push_back(SrcElts);
1882  }
1883 
1884  return new ShuffleVectorInst(InVal, V2,
1886  ShuffleMask));
1887 }
1888 
1889 static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
1890  return Value % Ty->getPrimitiveSizeInBits() == 0;
1891 }
1892 
1893 static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
1894  return Value / Ty->getPrimitiveSizeInBits();
1895 }
1896 
1897 /// V is a value which is inserted into a vector of VecEltTy.
1898 /// Look through the value to see if we can decompose it into
1899 /// insertions into the vector. See the example in the comment for
1900 /// OptimizeIntegerToVectorInsertions for the pattern this handles.
1901 /// The type of V is always a non-zero multiple of VecEltTy's size.
1902 /// Shift is the number of bits between the lsb of V and the lsb of
1903 /// the vector.
1904 ///
1905 /// This returns false if the pattern can't be matched or true if it can,
1906 /// filling in Elements with the elements found here.
1907 static bool collectInsertionElements(Value *V, unsigned Shift,
1908  SmallVectorImpl<Value *> &Elements,
1909  Type *VecEltTy, bool isBigEndian) {
1910  assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
1911  "Shift should be a multiple of the element type size");
1912 
1913  // Undef values never contribute useful bits to the result.
1914  if (isa<UndefValue>(V)) return true;
1915 
1916  // If we got down to a value of the right type, we win, try inserting into the
1917  // right element.
1918  if (V->getType() == VecEltTy) {
1919  // Inserting null doesn't actually insert any elements.
1920  if (Constant *C = dyn_cast<Constant>(V))
1921  if (C->isNullValue())
1922  return true;
1923 
1924  unsigned ElementIndex = getTypeSizeIndex(Shift, VecEltTy);
1925  if (isBigEndian)
1926  ElementIndex = Elements.size() - ElementIndex - 1;
1927 
1928  // Fail if multiple elements are inserted into this slot.
1929  if (Elements[ElementIndex])
1930  return false;
1931 
1932  Elements[ElementIndex] = V;
1933  return true;
1934  }
1935 
1936  if (Constant *C = dyn_cast<Constant>(V)) {
1937  // Figure out the # elements this provides, and bitcast it or slice it up
1938  // as required.
1939  unsigned NumElts = getTypeSizeIndex(C->getType()->getPrimitiveSizeInBits(),
1940  VecEltTy);
1941  // If the constant is the size of a vector element, we just need to bitcast
1942  // it to the right type so it gets properly inserted.
1943  if (NumElts == 1)
1945  Shift, Elements, VecEltTy, isBigEndian);
1946 
1947  // Okay, this is a constant that covers multiple elements. Slice it up into
1948  // pieces and insert each element-sized piece into the vector.
1949  if (!isa<IntegerType>(C->getType()))
1952  unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
1953  Type *ElementIntTy = IntegerType::get(C->getContext(), ElementSize);
1954 
1955  for (unsigned i = 0; i != NumElts; ++i) {
1956  unsigned ShiftI = Shift+i*ElementSize;
1958  ShiftI));
1959  Piece = ConstantExpr::getTrunc(Piece, ElementIntTy);
1960  if (!collectInsertionElements(Piece, ShiftI, Elements, VecEltTy,
1961  isBigEndian))
1962  return false;
1963  }
1964  return true;
1965  }
1966 
1967  if (!V->hasOneUse()) return false;
1968 
1970  if (!I) return false;
1971  switch (I->getOpcode()) {
1972  default: return false; // Unhandled case.
1973  case Instruction::BitCast:
1974  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1975  isBigEndian);
1976  case Instruction::ZExt:
1977  if (!isMultipleOfTypeSize(
1979  VecEltTy))
1980  return false;
1981  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1982  isBigEndian);
1983  case Instruction::Or:
1984  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1985  isBigEndian) &&
1986  collectInsertionElements(I->getOperand(1), Shift, Elements, VecEltTy,
1987  isBigEndian);
1988  case Instruction::Shl: {
1989  // Must be shifting by a constant that is a multiple of the element size.
1991  if (!CI) return false;
1992  Shift += CI->getZExtValue();
1993  if (!isMultipleOfTypeSize(Shift, VecEltTy)) return false;
1994  return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
1995  isBigEndian);
1996  }
1997 
1998  }
1999 }
2000 
2001 
2002 /// If the input is an 'or' instruction, we may be doing shifts and ors to
2003 /// assemble the elements of the vector manually.
2004 /// Try to rip the code out and replace it with insertelements. This is to
2005 /// optimize code like this:
2006 ///
2007 /// %tmp37 = bitcast float %inc to i32
2008 /// %tmp38 = zext i32 %tmp37 to i64
2009 /// %tmp31 = bitcast float %inc5 to i32
2010 /// %tmp32 = zext i32 %tmp31 to i64
2011 /// %tmp33 = shl i64 %tmp32, 32
2012 /// %ins35 = or i64 %tmp33, %tmp38
2013 /// %tmp43 = bitcast i64 %ins35 to <2 x float>
2014 ///
2015 /// Into two insertelements that do "buildvector{%inc, %inc5}".
2017  InstCombiner &IC) {
2018  VectorType *DestVecTy = cast<VectorType>(CI.getType());
2019  Value *IntInput = CI.getOperand(0);
2020 
2021  SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
2022  if (!collectInsertionElements(IntInput, 0, Elements,
2023  DestVecTy->getElementType(),
2024  IC.getDataLayout().isBigEndian()))
2025  return nullptr;
2026 
2027  // If we succeeded, we know that all of the element are specified by Elements
2028  // or are zero if Elements has a null entry. Recast this as a set of
2029  // insertions.
2030  Value *Result = Constant::getNullValue(CI.getType());
2031  for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
2032  if (!Elements[i]) continue; // Unset element.
2033 
2034  Result = IC.Builder.CreateInsertElement(Result, Elements[i],
2035  IC.Builder.getInt32(i));
2036  }
2037 
2038  return Result;
2039 }
2040 
2041 /// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
2042 /// vector followed by extract element. The backend tends to handle bitcasts of
2043 /// vectors better than bitcasts of scalars because vector registers are
2044 /// usually not type-specific like scalar integer or scalar floating-point.
2046  InstCombiner &IC) {
2047  // TODO: Create and use a pattern matcher for ExtractElementInst.
2048  auto *ExtElt = dyn_cast<ExtractElementInst>(BitCast.getOperand(0));
2049  if (!ExtElt || !ExtElt->hasOneUse())
2050  return nullptr;
2051 
2052  // The bitcast must be to a vectorizable type, otherwise we can't make a new
2053  // type to extract from.
2054  Type *DestType = BitCast.getType();
2055  if (!VectorType::isValidElementType(DestType))
2056  return nullptr;
2057 
2058  unsigned NumElts = ExtElt->getVectorOperandType()->getNumElements();
2059  auto *NewVecType = VectorType::get(DestType, NumElts);
2060  auto *NewBC = IC.Builder.CreateBitCast(ExtElt->getVectorOperand(),
2061  NewVecType, "bc");
2062  return ExtractElementInst::Create(NewBC, ExtElt->getIndexOperand());
2063 }
2064 
2065 /// Change the type of a bitwise logic operation if we can eliminate a bitcast.
2067  InstCombiner::BuilderTy &Builder) {
2068  Type *DestTy = BitCast.getType();
2069  BinaryOperator *BO;
2070  if (!DestTy->isIntOrIntVectorTy() ||
2071  !match(BitCast.getOperand(0), m_OneUse(m_BinOp(BO))) ||
2072  !BO->isBitwiseLogicOp())
2073  return nullptr;
2074 
2075  // FIXME: This transform is restricted to vector types to avoid backend
2076  // problems caused by creating potentially illegal operations. If a fix-up is
2077  // added to handle that situation, we can remove this check.
2078  if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy())
2079  return nullptr;
2080 
2081  Value *X;
2082  if (match(BO->getOperand(0), m_OneUse(m_BitCast(m_Value(X)))) &&
2083  X->getType() == DestTy && !isa<Constant>(X)) {
2084  // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y))
2085  Value *CastedOp1 = Builder.CreateBitCast(BO->getOperand(1), DestTy);
2086  return BinaryOperator::Create(BO->getOpcode(), X, CastedOp1);
2087  }
2088 
2089  if (match(BO->getOperand(1), m_OneUse(m_BitCast(m_Value(X)))) &&
2090  X->getType() == DestTy && !isa<Constant>(X)) {
2091  // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X)
2092  Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
2093  return BinaryOperator::Create(BO->getOpcode(), CastedOp0, X);
2094  }
2095 
2096  // Canonicalize vector bitcasts to come before vector bitwise logic with a
2097  // constant. This eases recognition of special constants for later ops.
2098  // Example:
2099  // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
2100  Constant *C;
2101  if (match(BO->getOperand(1), m_Constant(C))) {
2102  // bitcast (logic X, C) --> logic (bitcast X, C')
2103  Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
2104  Value *CastedC = ConstantExpr::getBitCast(C, DestTy);
2105  return BinaryOperator::Create(BO->getOpcode(), CastedOp0, CastedC);
2106  }
2107 
2108  return nullptr;
2109 }
2110 
2111 /// Change the type of a select if we can eliminate a bitcast.
2113  InstCombiner::BuilderTy &Builder) {
2114  Value *Cond, *TVal, *FVal;
2115  if (!match(BitCast.getOperand(0),
2116  m_OneUse(m_Select(m_Value(Cond), m_Value(TVal), m_Value(FVal)))))
2117  return nullptr;
2118 
2119  // A vector select must maintain the same number of elements in its operands.
2120  Type *CondTy = Cond->getType();
2121  Type *DestTy = BitCast.getType();
2122  if (CondTy->isVectorTy()) {
2123  if (!DestTy->isVectorTy())
2124  return nullptr;
2125  if (DestTy->getVectorNumElements() != CondTy->getVectorNumElements())
2126  return nullptr;
2127  }
2128 
2129  // FIXME: This transform is restricted from changing the select between
2130  // scalars and vectors to avoid backend problems caused by creating
2131  // potentially illegal operations. If a fix-up is added to handle that
2132  // situation, we can remove this check.
2133  if (DestTy->isVectorTy() != TVal->getType()->isVectorTy())
2134  return nullptr;
2135 
2136  auto *Sel = cast<Instruction>(BitCast.getOperand(0));
2137  Value *X;
2138  if (match(TVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy &&
2139  !isa<Constant>(X)) {
2140  // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y))
2141  Value *CastedVal = Builder.CreateBitCast(FVal, DestTy);
2142  return SelectInst::Create(Cond, X, CastedVal, "", nullptr, Sel);
2143  }
2144 
2145  if (match(FVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy &&
2146  !isa<Constant>(X)) {
2147  // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X)
2148  Value *CastedVal = Builder.CreateBitCast(TVal, DestTy);
2149  return SelectInst::Create(Cond, CastedVal, X, "", nullptr, Sel);
2150  }
2151 
2152  return nullptr;
2153 }
2154 
2155 /// Check if all users of CI are StoreInsts.
2156 static bool hasStoreUsersOnly(CastInst &CI) {
2157  for (User *U : CI.users()) {
2158  if (!isa<StoreInst>(U))
2159  return false;
2160  }
2161  return true;
2162 }
2163 
2164 /// This function handles following case
2165 ///
2166 /// A -> B cast
2167 /// PHI
2168 /// B -> A cast
2169 ///
2170 /// All the related PHI nodes can be replaced by new PHI nodes with type A.
2171 /// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
2172 Instruction *InstCombiner::optimizeBitCastFromPhi(CastInst &CI, PHINode *PN) {
2173  // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp.
2174  if (hasStoreUsersOnly(CI))
2175  return nullptr;
2176 
2177  Value *Src = CI.getOperand(0);
2178  Type *SrcTy = Src->getType(); // Type B
2179  Type *DestTy = CI.getType(); // Type A
2180 
2181  SmallVector<PHINode *, 4> PhiWorklist;
2182  SmallSetVector<PHINode *, 4> OldPhiNodes;
2183 
2184  // Find all of the A->B casts and PHI nodes.
2185  // We need to inpect all related PHI nodes, but PHIs can be cyclic, so
2186  // OldPhiNodes is used to track all known PHI nodes, before adding a new
2187  // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
2188  PhiWorklist.push_back(PN);
2189  OldPhiNodes.insert(PN);
2190  while (!PhiWorklist.empty()) {
2191  auto *OldPN = PhiWorklist.pop_back_val();
2192  for (Value *IncValue : OldPN->incoming_values()) {
2193  if (isa<Constant>(IncValue))
2194  continue;
2195 
2196  if (auto *LI = dyn_cast<LoadInst>(IncValue)) {
2197  // If there is a sequence of one or more load instructions, each loaded
2198  // value is used as address of later load instruction, bitcast is
2199  // necessary to change the value type, don't optimize it. For
2200  // simplicity we give up if the load address comes from another load.
2201  Value *Addr = LI->getOperand(0);
2202  if (Addr == &CI || isa<LoadInst>(Addr))
2203  return nullptr;
2204  if (LI->hasOneUse() && LI->isSimple())
2205  continue;
2206  // If a LoadInst has more than one use, changing the type of loaded
2207  // value may create another bitcast.
2208  return nullptr;
2209  }
2210 
2211  if (auto *PNode = dyn_cast<PHINode>(IncValue)) {
2212  if (OldPhiNodes.insert(PNode))
2213  PhiWorklist.push_back(PNode);
2214  continue;
2215  }
2216 
2217  auto *BCI = dyn_cast<BitCastInst>(IncValue);
2218  // We can't handle other instructions.
2219  if (!BCI)
2220  return nullptr;
2221 
2222  // Verify it's a A->B cast.
2223  Type *TyA = BCI->getOperand(0)->getType();
2224  Type *TyB = BCI->getType();
2225  if (TyA != DestTy || TyB != SrcTy)
2226  return nullptr;
2227  }
2228  }
2229 
2230  // For each old PHI node, create a corresponding new PHI node with a type A.
2232  for (auto *OldPN : OldPhiNodes) {
2233  Builder.SetInsertPoint(OldPN);
2234  PHINode *NewPN = Builder.CreatePHI(DestTy, OldPN->getNumOperands());
2235  NewPNodes[OldPN] = NewPN;
2236  }
2237 
2238  // Fill in the operands of new PHI nodes.
2239  for (auto *OldPN : OldPhiNodes) {
2240  PHINode *NewPN = NewPNodes[OldPN];
2241  for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
2242  Value *V = OldPN->getOperand(j);
2243  Value *NewV = nullptr;
2244  if (auto *C = dyn_cast<Constant>(V)) {
2245  NewV = ConstantExpr::getBitCast(C, DestTy);
2246  } else if (auto *LI = dyn_cast<LoadInst>(V)) {
2247  Builder.SetInsertPoint(LI->getNextNode());
2248  NewV = Builder.CreateBitCast(LI, DestTy);
2249  Worklist.Add(LI);
2250  } else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
2251  NewV = BCI->getOperand(0);
2252  } else if (auto *PrevPN = dyn_cast<PHINode>(V)) {
2253  NewV = NewPNodes[PrevPN];
2254  }
2255  assert(NewV);
2256  NewPN->addIncoming(NewV, OldPN->getIncomingBlock(j));
2257  }
2258  }
2259 
2260  // If there is a store with type B, change it to type A.
2261  for (User *U : PN->users()) {
2262  auto *SI = dyn_cast<StoreInst>(U);
2263  if (SI && SI->isSimple() && SI->getOperand(0) == PN) {
2264  Builder.SetInsertPoint(SI);
2265  auto *NewBC =
2266  cast<BitCastInst>(Builder.CreateBitCast(NewPNodes[PN], SrcTy));
2267  SI->setOperand(0, NewBC);
2268  Worklist.Add(SI);
2269  assert(hasStoreUsersOnly(*NewBC));
2270  }
2271  }
2272 
2273  return replaceInstUsesWith(CI, NewPNodes[PN]);
2274 }
2275 
2277  // If the operands are integer typed then apply the integer transforms,
2278  // otherwise just apply the common ones.
2279  Value *Src = CI.getOperand(0);
2280  Type *SrcTy = Src->getType();
2281  Type *DestTy = CI.getType();
2282 
2283  // Get rid of casts from one type to the same type. These are useless and can
2284  // be replaced by the operand.
2285  if (DestTy == Src->getType())
2286  return replaceInstUsesWith(CI, Src);
2287 
2288  if (PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
2289  PointerType *SrcPTy = cast<PointerType>(SrcTy);
2290  Type *DstElTy = DstPTy->getElementType();
2291  Type *SrcElTy = SrcPTy->getElementType();
2292 
2293  // Casting pointers between the same type, but with different address spaces
2294  // is an addrspace cast rather than a bitcast.
2295  if ((DstElTy == SrcElTy) &&
2296  (DstPTy->getAddressSpace() != SrcPTy->getAddressSpace()))
2297  return new AddrSpaceCastInst(Src, DestTy);
2298 
2299  // If we are casting a alloca to a pointer to a type of the same
2300  // size, rewrite the allocation instruction to allocate the "right" type.
2301  // There is no need to modify malloc calls because it is their bitcast that
2302  // needs to be cleaned up.
2303  if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
2304  if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
2305  return V;
2306 
2307  // When the type pointed to is not sized the cast cannot be
2308  // turned into a gep.
2309  Type *PointeeType =
2310  cast<PointerType>(Src->getType()->getScalarType())->getElementType();
2311  if (!PointeeType->isSized())
2312  return nullptr;
2313 
2314  // If the source and destination are pointers, and this cast is equivalent
2315  // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
2316  // This can enhance SROA and other transforms that want type-safe pointers.
2317  unsigned NumZeros = 0;
2318  while (SrcElTy != DstElTy &&
2319  isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
2320  SrcElTy->getNumContainedTypes() /* not "{}" */) {
2321  SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(0U);
2322  ++NumZeros;
2323  }
2324 
2325  // If we found a path from the src to dest, create the getelementptr now.
2326  if (SrcElTy == DstElTy) {
2327  SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder.getInt32(0));
2328  return GetElementPtrInst::CreateInBounds(Src, Idxs);
2329  }
2330  }
2331 
2332  if (VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
2333  if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) {
2334  Value *Elem = Builder.CreateBitCast(Src, DestVTy->getElementType());
2335  return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
2337  // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
2338  }
2339 
2340  if (isa<IntegerType>(SrcTy)) {
2341  // If this is a cast from an integer to vector, check to see if the input
2342  // is a trunc or zext of a bitcast from vector. If so, we can replace all
2343  // the casts with a shuffle and (potentially) a bitcast.
2344  if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) {
2345  CastInst *SrcCast = cast<CastInst>(Src);
2346  if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
2347  if (isa<VectorType>(BCIn->getOperand(0)->getType()))
2348  if (Instruction *I = optimizeVectorResize(BCIn->getOperand(0),
2349  cast<VectorType>(DestTy), *this))
2350  return I;
2351  }
2352 
2353  // If the input is an 'or' instruction, we may be doing shifts and ors to
2354  // assemble the elements of the vector manually. Try to rip the code out
2355  // and replace it with insertelements.
2356  if (Value *V = optimizeIntegerToVectorInsertions(CI, *this))
2357  return replaceInstUsesWith(CI, V);
2358  }
2359  }
2360 
2361  if (VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
2362  if (SrcVTy->getNumElements() == 1) {
2363  // If our destination is not a vector, then make this a straight
2364  // scalar-scalar cast.
2365  if (!DestTy->isVectorTy()) {
2366  Value *Elem =
2367  Builder.CreateExtractElement(Src,
2369  return CastInst::Create(Instruction::BitCast, Elem, DestTy);
2370  }
2371 
2372  // Otherwise, see if our source is an insert. If so, then use the scalar
2373  // component directly.
2374  if (InsertElementInst *IEI =
2375  dyn_cast<InsertElementInst>(CI.getOperand(0)))
2376  return CastInst::Create(Instruction::BitCast, IEI->getOperand(1),
2377  DestTy);
2378  }
2379  }
2380 
2381  if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
2382  // Okay, we have (bitcast (shuffle ..)). Check to see if this is
2383  // a bitcast to a vector with the same # elts.
2384  if (SVI->hasOneUse() && DestTy->isVectorTy() &&
2385  DestTy->getVectorNumElements() == SVI->getType()->getNumElements() &&
2386  SVI->getType()->getNumElements() ==
2387  SVI->getOperand(0)->getType()->getVectorNumElements()) {
2388  BitCastInst *Tmp;
2389  // If either of the operands is a cast from CI.getType(), then
2390  // evaluating the shuffle in the casted destination's type will allow
2391  // us to eliminate at least one cast.
2392  if (((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(0))) &&
2393  Tmp->getOperand(0)->getType() == DestTy) ||
2394  ((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(1))) &&
2395  Tmp->getOperand(0)->getType() == DestTy)) {
2396  Value *LHS = Builder.CreateBitCast(SVI->getOperand(0), DestTy);
2397  Value *RHS = Builder.CreateBitCast(SVI->getOperand(1), DestTy);
2398  // Return a new shuffle vector. Use the same element ID's, as we
2399  // know the vector types match #elts.
2400  return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
2401  }
2402  }
2403  }
2404 
2405  // Handle the A->B->A cast, and there is an intervening PHI node.
2406  if (PHINode *PN = dyn_cast<PHINode>(Src))
2407  if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
2408  return I;
2409 
2410  if (Instruction *I = canonicalizeBitCastExtElt(CI, *this))
2411  return I;
2412 
2413  if (Instruction *I = foldBitCastBitwiseLogic(CI, Builder))
2414  return I;
2415 
2416  if (Instruction *I = foldBitCastSelect(CI, Builder))
2417  return I;
2418 
2419  if (SrcTy->isPointerTy())
2420  return commonPointerCastTransforms(CI);
2421  return commonCastTransforms(CI);
2422 }
2423 
2425  // If the destination pointer element type is not the same as the source's
2426  // first do a bitcast to the destination type, and then the addrspacecast.
2427  // This allows the cast to be exposed to other transforms.
2428  Value *Src = CI.getOperand(0);
2429  PointerType *SrcTy = cast<PointerType>(Src->getType()->getScalarType());
2430  PointerType *DestTy = cast<PointerType>(CI.getType()->getScalarType());
2431 
2432  Type *DestElemTy = DestTy->getElementType();
2433  if (SrcTy->getElementType() != DestElemTy) {
2434  Type *MidTy = PointerType::get(DestElemTy, SrcTy->getAddressSpace());
2435  if (VectorType *VT = dyn_cast<VectorType>(CI.getType())) {
2436  // Handle vectors of pointers.
2437  MidTy = VectorType::get(MidTy, VT->getNumElements());
2438  }
2439 
2440  Value *NewBitCast = Builder.CreateBitCast(Src, MidTy);
2441  return new AddrSpaceCastInst(NewBitCast, CI.getType());
2442  }
2443 
2444  return commonPointerCastTransforms(CI);
2445 }
static BinaryOperator * CreateFMulFMF(Value *V1, Value *V2, BinaryOperator *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:178
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:750
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:934
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:632
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:607
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:1563
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:655
DiagnosticInfoOptimizationBase::Argument NV
This class represents lattice values for constants.
Definition: AllocatorList.h:24
BinaryOps getOpcode() const
Definition: InstrTypes.h:312
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.
void push_back(const T &Elt)
Definition: SmallVector.h:218
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:630
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:780
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:705
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:173
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:365
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1509
BinOpPred_match< LHS, RHS, is_logical_shift_op > m_LogicalShift(const LHS &L, const RHS &R)
Matches logical shift operations.
Definition: PatternMatch.h:942
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:265
Instruction * visitFPExt(CastInst &CI)
Instruction * FoldItoFPtoI(Instruction &FI)
unsigned countTrailingZeros() const
Count the number of trailing zero bits.
Definition: APInt.h:1632
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:1613
BinaryOp_match< LHS, RHS, Instruction::Xor > m_Xor(const LHS &L, const RHS &R)
Definition: PatternMatch.h:762
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:349
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:1286
static Constant * getLShr(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2317
static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear, InstCombiner &IC, Instruction *CxtI)
Determine if the specified value can be computed in the specified wider type and produce the same low...
static Optional< unsigned > getOpcode(ArrayRef< VPValue *> Values)
Returns the opcode of Values or ~0 if they do not all agree.
Definition: VPlanSLP.cpp:197
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:1665
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:602
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:621
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:1808
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:292
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:1773
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:774
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:1658
constexpr bool isPowerOf2_32(uint32_t Value)
Return true if the argument is a power of two > 0.
Definition: MathExtras.h:429
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
BinaryOp_match< LHS, RHS, Instruction::Or > m_Or(const LHS &L, const RHS &R)
Definition: PatternMatch.h:756
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1185
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:310
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:503
BinaryOp_match< LHS, RHS, Instruction::Shl > m_Shl(const LHS &L, const RHS &R)
Definition: PatternMatch.h:768
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:642
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:319
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:1415
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:516
Type * getAllocatedType() const
Return the type that is being allocated by the instruction.
Definition: Instructions.h:106
signed greater than
Definition: InstrTypes.h:669
const APFloat & getValueAPF() const
Definition: Constants.h:303
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:671
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:1637
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:622
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:609
unsigned getNumIncomingValues() const
Return the number of incoming edges.
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1293
static BinaryOperator * CreateFDivFMF(Value *V1, Value *V2, BinaryOperator *FMFSource, const Twine &Name="")
Definition: InstrTypes.h:183
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
BinaryOp_match< cst_pred_ty< is_zero_int >, ValTy, Instruction::Sub > m_Neg(const ValTy &V)
Matches a &#39;Neg&#39; as &#39;sub 0, V&#39;.
unsigned getVectorNumElements() const
Definition: DerivedTypes.h: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:717
Instruction * visitTrunc(TruncInst &CI)
static Type * shrinkFPConstantVector(Value *V)
FNeg_match< OpTy > m_FNeg(const OpTy &X)
Match &#39;fneg X&#39; as &#39;fsub -0.0, X&#39;.
Definition: PatternMatch.h:690
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
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:215
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:193
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:606
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:1596
specific_intval m_SpecificInt(uint64_t V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:580
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:2584
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