1 //===- InstCombineVectorOps.cpp -------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements instcombine for ExtractElement, InsertElement and
13 //===----------------------------------------------------------------------===//
15 #include "InstCombine.h"
18 /// CheapToScalarize - Return true if the value is cheaper to scalarize than it
19 /// is to leave as a vector operation.
20 static bool CheapToScalarize(Value *V, bool isConstant) {
21 if (isa<ConstantAggregateZero>(V))
23 if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
24 if (isConstant) return true;
25 // If all elts are the same, we can extract.
26 Constant *Op0 = C->getOperand(0);
27 for (unsigned i = 1; i < C->getNumOperands(); ++i)
28 if (C->getOperand(i) != Op0)
32 Instruction *I = dyn_cast<Instruction>(V);
35 // Insert element gets simplified to the inserted element or is deleted if
36 // this is constant idx extract element and its a constant idx insertelt.
37 if (I->getOpcode() == Instruction::InsertElement && isConstant &&
38 isa<ConstantInt>(I->getOperand(2)))
40 if (I->getOpcode() == Instruction::Load && I->hasOneUse())
42 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
43 if (BO->hasOneUse() &&
44 (CheapToScalarize(BO->getOperand(0), isConstant) ||
45 CheapToScalarize(BO->getOperand(1), isConstant)))
47 if (CmpInst *CI = dyn_cast<CmpInst>(I))
48 if (CI->hasOneUse() &&
49 (CheapToScalarize(CI->getOperand(0), isConstant) ||
50 CheapToScalarize(CI->getOperand(1), isConstant)))
56 /// getShuffleMask - Read and decode a shufflevector mask.
57 /// Turn undef elements into negative values.
58 static SmallVector<int, 16> getShuffleMask(const ShuffleVectorInst *SVI) {
59 unsigned NElts = SVI->getType()->getNumElements();
60 if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
61 return SmallVector<int, 16>(NElts, 0);
62 if (isa<UndefValue>(SVI->getOperand(2)))
63 return SmallVector<int, 16>(NElts, -1);
65 SmallVector<int, 16> Result;
66 const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
67 for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
68 if (isa<UndefValue>(*i))
69 Result.push_back(-1); // undef
71 Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
75 /// FindScalarElement - Given a vector and an element number, see if the scalar
76 /// value is already around as a register, for example if it were inserted then
77 /// extracted from the vector.
78 static Value *FindScalarElement(Value *V, unsigned EltNo) {
79 assert(V->getType()->isVectorTy() && "Not looking at a vector?");
80 VectorType *PTy = cast<VectorType>(V->getType());
81 unsigned Width = PTy->getNumElements();
82 if (EltNo >= Width) // Out of range access.
83 return UndefValue::get(PTy->getElementType());
85 if (isa<UndefValue>(V))
86 return UndefValue::get(PTy->getElementType());
87 if (isa<ConstantAggregateZero>(V))
88 return Constant::getNullValue(PTy->getElementType());
89 if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
90 return CP->getOperand(EltNo);
92 if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
93 // If this is an insert to a variable element, we don't know what it is.
94 if (!isa<ConstantInt>(III->getOperand(2)))
96 unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
98 // If this is an insert to the element we are looking for, return the
101 return III->getOperand(1);
103 // Otherwise, the insertelement doesn't modify the value, recurse on its
105 return FindScalarElement(III->getOperand(0), EltNo);
108 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
110 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
111 int InEl = SVI->getMaskValue(EltNo);
113 return UndefValue::get(PTy->getElementType());
114 if (InEl < (int)LHSWidth)
115 return FindScalarElement(SVI->getOperand(0), InEl);
116 return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
119 // Otherwise, we don't know.
123 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
124 // If vector val is undef, replace extract with scalar undef.
125 if (isa<UndefValue>(EI.getOperand(0)))
126 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
128 // If vector val is constant 0, replace extract with scalar 0.
129 if (isa<ConstantAggregateZero>(EI.getOperand(0)))
130 return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
132 if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
133 // If vector val is constant with all elements the same, replace EI with
134 // that element. When the elements are not identical, we cannot replace yet
135 // (we do that below, but only when the index is constant).
136 Constant *op0 = C->getOperand(0);
137 for (unsigned i = 1; i != C->getNumOperands(); ++i)
138 if (C->getOperand(i) != op0) {
143 return ReplaceInstUsesWith(EI, op0);
146 // If extracting a specified index from the vector, see if we can recursively
147 // find a previously computed scalar that was inserted into the vector.
148 if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
149 unsigned IndexVal = IdxC->getZExtValue();
150 unsigned VectorWidth = EI.getVectorOperandType()->getNumElements();
152 // If this is extracting an invalid index, turn this into undef, to avoid
153 // crashing the code below.
154 if (IndexVal >= VectorWidth)
155 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
157 // This instruction only demands the single element from the input vector.
158 // If the input vector has a single use, simplify it based on this use
160 if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
161 APInt UndefElts(VectorWidth, 0);
162 APInt DemandedMask(VectorWidth, 0);
163 DemandedMask.setBit(IndexVal);
164 if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
165 DemandedMask, UndefElts)) {
171 if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
172 return ReplaceInstUsesWith(EI, Elt);
174 // If the this extractelement is directly using a bitcast from a vector of
175 // the same number of elements, see if we can find the source element from
176 // it. In this case, we will end up needing to bitcast the scalars.
177 if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
179 dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
180 if (VT->getNumElements() == VectorWidth)
181 if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
182 return new BitCastInst(Elt, EI.getType());
186 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
187 // Push extractelement into predecessor operation if legal and
188 // profitable to do so
189 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
190 if (I->hasOneUse() &&
191 CheapToScalarize(BO, isa<ConstantInt>(EI.getOperand(1)))) {
193 Builder->CreateExtractElement(BO->getOperand(0), EI.getOperand(1),
194 EI.getName()+".lhs");
196 Builder->CreateExtractElement(BO->getOperand(1), EI.getOperand(1),
197 EI.getName()+".rhs");
198 return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
200 } else if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
201 // Extracting the inserted element?
202 if (IE->getOperand(2) == EI.getOperand(1))
203 return ReplaceInstUsesWith(EI, IE->getOperand(1));
204 // If the inserted and extracted elements are constants, they must not
205 // be the same value, extract from the pre-inserted value instead.
206 if (isa<Constant>(IE->getOperand(2)) && isa<Constant>(EI.getOperand(1))) {
207 Worklist.AddValue(EI.getOperand(0));
208 EI.setOperand(0, IE->getOperand(0));
211 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
212 // If this is extracting an element from a shufflevector, figure out where
213 // it came from and extract from the appropriate input element instead.
214 if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
215 int SrcIdx = SVI->getMaskValue(Elt->getZExtValue());
218 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
221 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
222 if (SrcIdx < (int)LHSWidth)
223 Src = SVI->getOperand(0);
226 Src = SVI->getOperand(1);
228 Type *Int32Ty = Type::getInt32Ty(EI.getContext());
229 return ExtractElementInst::Create(Src,
230 ConstantInt::get(Int32Ty,
233 } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
234 // Canonicalize extractelement(cast) -> cast(extractelement)
235 // bitcasts can change the number of vector elements and they cost nothing
236 if (CI->hasOneUse() && EI.hasOneUse() &&
237 (CI->getOpcode() != Instruction::BitCast)) {
238 Value *EE = Builder->CreateExtractElement(CI->getOperand(0),
239 EI.getIndexOperand());
240 return CastInst::Create(CI->getOpcode(), EE, EI.getType());
247 /// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
248 /// elements from either LHS or RHS, return the shuffle mask and true.
249 /// Otherwise, return false.
250 static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
251 std::vector<Constant*> &Mask) {
252 assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
253 "Invalid CollectSingleShuffleElements");
254 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
256 if (isa<UndefValue>(V)) {
257 Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
262 for (unsigned i = 0; i != NumElts; ++i)
263 Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
268 for (unsigned i = 0; i != NumElts; ++i)
269 Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()),
274 if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
275 // If this is an insert of an extract from some other vector, include it.
276 Value *VecOp = IEI->getOperand(0);
277 Value *ScalarOp = IEI->getOperand(1);
278 Value *IdxOp = IEI->getOperand(2);
280 if (!isa<ConstantInt>(IdxOp))
282 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
284 if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
285 // Okay, we can handle this if the vector we are insertinting into is
287 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
288 // If so, update the mask to reflect the inserted undef.
289 Mask[InsertedIdx] = UndefValue::get(Type::getInt32Ty(V->getContext()));
292 } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
293 if (isa<ConstantInt>(EI->getOperand(1)) &&
294 EI->getOperand(0)->getType() == V->getType()) {
295 unsigned ExtractedIdx =
296 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
298 // This must be extracting from either LHS or RHS.
299 if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
300 // Okay, we can handle this if the vector we are insertinting into is
302 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
303 // If so, update the mask to reflect the inserted value.
304 if (EI->getOperand(0) == LHS) {
305 Mask[InsertedIdx % NumElts] =
306 ConstantInt::get(Type::getInt32Ty(V->getContext()),
309 assert(EI->getOperand(0) == RHS);
310 Mask[InsertedIdx % NumElts] =
311 ConstantInt::get(Type::getInt32Ty(V->getContext()),
312 ExtractedIdx+NumElts);
320 // TODO: Handle shufflevector here!
325 /// CollectShuffleElements - We are building a shuffle of V, using RHS as the
326 /// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
327 /// that computes V and the LHS value of the shuffle.
328 static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
330 assert(V->getType()->isVectorTy() &&
331 (RHS == 0 || V->getType() == RHS->getType()) &&
333 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
335 if (isa<UndefValue>(V)) {
336 Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
338 } else if (isa<ConstantAggregateZero>(V)) {
339 Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(V->getContext()),0));
341 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
342 // If this is an insert of an extract from some other vector, include it.
343 Value *VecOp = IEI->getOperand(0);
344 Value *ScalarOp = IEI->getOperand(1);
345 Value *IdxOp = IEI->getOperand(2);
347 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
348 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
349 EI->getOperand(0)->getType() == V->getType()) {
350 unsigned ExtractedIdx =
351 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
352 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
354 // Either the extracted from or inserted into vector must be RHSVec,
355 // otherwise we'd end up with a shuffle of three inputs.
356 if (EI->getOperand(0) == RHS || RHS == 0) {
357 RHS = EI->getOperand(0);
358 Value *V = CollectShuffleElements(VecOp, Mask, RHS);
359 Mask[InsertedIdx % NumElts] =
360 ConstantInt::get(Type::getInt32Ty(V->getContext()),
361 NumElts+ExtractedIdx);
366 Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
367 // Everything but the extracted element is replaced with the RHS.
368 for (unsigned i = 0; i != NumElts; ++i) {
369 if (i != InsertedIdx)
370 Mask[i] = ConstantInt::get(Type::getInt32Ty(V->getContext()),
376 // If this insertelement is a chain that comes from exactly these two
377 // vectors, return the vector and the effective shuffle.
378 if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
379 return EI->getOperand(0);
383 // TODO: Handle shufflevector here!
385 // Otherwise, can't do anything fancy. Return an identity vector.
386 for (unsigned i = 0; i != NumElts; ++i)
387 Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
391 Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
392 Value *VecOp = IE.getOperand(0);
393 Value *ScalarOp = IE.getOperand(1);
394 Value *IdxOp = IE.getOperand(2);
396 // Inserting an undef or into an undefined place, remove this.
397 if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
398 ReplaceInstUsesWith(IE, VecOp);
400 // If the inserted element was extracted from some other vector, and if the
401 // indexes are constant, try to turn this into a shufflevector operation.
402 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
403 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
404 EI->getOperand(0)->getType() == IE.getType()) {
405 unsigned NumVectorElts = IE.getType()->getNumElements();
406 unsigned ExtractedIdx =
407 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
408 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
410 if (ExtractedIdx >= NumVectorElts) // Out of range extract.
411 return ReplaceInstUsesWith(IE, VecOp);
413 if (InsertedIdx >= NumVectorElts) // Out of range insert.
414 return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
416 // If we are extracting a value from a vector, then inserting it right
417 // back into the same place, just use the input vector.
418 if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
419 return ReplaceInstUsesWith(IE, VecOp);
421 // If this insertelement isn't used by some other insertelement, turn it
422 // (and any insertelements it points to), into one big shuffle.
423 if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
424 std::vector<Constant*> Mask;
426 Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
427 if (RHS == 0) RHS = UndefValue::get(LHS->getType());
428 // We now have a shuffle of LHS, RHS, Mask.
429 return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask));
434 unsigned VWidth = cast<VectorType>(VecOp->getType())->getNumElements();
435 APInt UndefElts(VWidth, 0);
436 APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
437 if (Value *V = SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts)) {
439 return ReplaceInstUsesWith(IE, V);
447 Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
448 Value *LHS = SVI.getOperand(0);
449 Value *RHS = SVI.getOperand(1);
450 SmallVector<int, 16> Mask = getShuffleMask(&SVI);
452 bool MadeChange = false;
454 // Undefined shuffle mask -> undefined value.
455 if (isa<UndefValue>(SVI.getOperand(2)))
456 return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
458 unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
460 APInt UndefElts(VWidth, 0);
461 APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
462 if (Value *V = SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
464 return ReplaceInstUsesWith(SVI, V);
465 LHS = SVI.getOperand(0);
466 RHS = SVI.getOperand(1);
470 unsigned LHSWidth = cast<VectorType>(LHS->getType())->getNumElements();
472 // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
473 // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
474 if (LHS == RHS || isa<UndefValue>(LHS)) {
475 if (isa<UndefValue>(LHS) && LHS == RHS) {
476 // shuffle(undef,undef,mask) -> undef.
477 Value* result = (VWidth == LHSWidth)
478 ? LHS : UndefValue::get(SVI.getType());
479 return ReplaceInstUsesWith(SVI, result);
482 // Remap any references to RHS to use LHS.
483 std::vector<Constant*> Elts;
484 for (unsigned i = 0, e = LHSWidth; i != VWidth; ++i) {
486 Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
488 if ((Mask[i] >= (int)e && isa<UndefValue>(RHS)) ||
489 (Mask[i] < (int)e && isa<UndefValue>(LHS))) {
490 Mask[i] = -1; // Turn into undef.
491 Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
493 Mask[i] = Mask[i] % e; // Force to LHS.
494 Elts.push_back(ConstantInt::get(Type::getInt32Ty(SVI.getContext()),
499 SVI.setOperand(0, SVI.getOperand(1));
500 SVI.setOperand(1, UndefValue::get(RHS->getType()));
501 SVI.setOperand(2, ConstantVector::get(Elts));
502 LHS = SVI.getOperand(0);
503 RHS = SVI.getOperand(1);
507 if (VWidth == LHSWidth) {
508 // Analyze the shuffle, are the LHS or RHS and identity shuffles?
509 bool isLHSID = true, isRHSID = true;
511 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
512 if (Mask[i] < 0) continue; // Ignore undef values.
513 // Is this an identity shuffle of the LHS value?
514 isLHSID &= (Mask[i] == (int)i);
516 // Is this an identity shuffle of the RHS value?
517 isRHSID &= (Mask[i]-e == i);
520 // Eliminate identity shuffles.
521 if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
522 if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
525 // If the LHS is a shufflevector itself, see if we can combine it with this
526 // one without producing an unusual shuffle.
527 // Cases that might be simplified:
529 // x1=shuffle(v1,v2,mask1)
530 // x=shuffle(x1,undef,mask)
532 // x=shuffle(v1,undef,newMask)
533 // newMask[i] = (mask[i] < x1.size()) ? mask1[mask[i]] : -1
535 // x1=shuffle(v1,undef,mask1)
536 // x=shuffle(x1,x2,mask)
537 // where v1.size() == mask1.size()
539 // x=shuffle(v1,x2,newMask)
540 // newMask[i] = (mask[i] < x1.size()) ? mask1[mask[i]] : mask[i]
542 // x2=shuffle(v2,undef,mask2)
543 // x=shuffle(x1,x2,mask)
544 // where v2.size() == mask2.size()
546 // x=shuffle(x1,v2,newMask)
547 // newMask[i] = (mask[i] < x1.size())
548 // ? mask[i] : mask2[mask[i]-x1.size()]+x1.size()
550 // x1=shuffle(v1,undef,mask1)
551 // x2=shuffle(v2,undef,mask2)
552 // x=shuffle(x1,x2,mask)
553 // where v1.size() == v2.size()
555 // x=shuffle(v1,v2,newMask)
556 // newMask[i] = (mask[i] < x1.size())
557 // ? mask1[mask[i]] : mask2[mask[i]-x1.size()]+v1.size()
559 // Here we are really conservative:
560 // we are absolutely afraid of producing a shuffle mask not in the input
561 // program, because the code gen may not be smart enough to turn a merged
562 // shuffle into two specific shuffles: it may produce worse code. As such,
563 // we only merge two shuffles if the result is either a splat or one of the
564 // input shuffle masks. In this case, merging the shuffles just removes
565 // one instruction, which we know is safe. This is good for things like
566 // turning: (splat(splat)) -> splat, or
567 // merge(V[0..n], V[n+1..2n]) -> V[0..2n]
568 ShuffleVectorInst* LHSShuffle = dyn_cast<ShuffleVectorInst>(LHS);
569 ShuffleVectorInst* RHSShuffle = dyn_cast<ShuffleVectorInst>(RHS);
571 if (!isa<UndefValue>(LHSShuffle->getOperand(1)) && !isa<UndefValue>(RHS))
574 if (!isa<UndefValue>(RHSShuffle->getOperand(1)))
576 if (!LHSShuffle && !RHSShuffle)
577 return MadeChange ? &SVI : 0;
579 Value* LHSOp0 = NULL;
580 Value* LHSOp1 = NULL;
581 Value* RHSOp0 = NULL;
582 unsigned LHSOp0Width = 0;
583 unsigned RHSOp0Width = 0;
585 LHSOp0 = LHSShuffle->getOperand(0);
586 LHSOp1 = LHSShuffle->getOperand(1);
587 LHSOp0Width = cast<VectorType>(LHSOp0->getType())->getNumElements();
590 RHSOp0 = RHSShuffle->getOperand(0);
591 RHSOp0Width = cast<VectorType>(RHSOp0->getType())->getNumElements();
597 if (isa<UndefValue>(RHS)) {
602 else if (LHSOp0Width == LHSWidth) {
607 if (RHSShuffle && RHSOp0Width == LHSWidth) {
611 if (LHSOp0 == RHSOp0) {
616 if (newLHS == LHS && newRHS == RHS)
617 return MadeChange ? &SVI : 0;
619 SmallVector<int, 16> LHSMask;
620 SmallVector<int, 16> RHSMask;
622 LHSMask = getShuffleMask(LHSShuffle);
624 if (RHSShuffle && newRHS != RHS) {
625 RHSMask = getShuffleMask(RHSShuffle);
627 unsigned newLHSWidth = (newLHS != LHS) ? LHSOp0Width : LHSWidth;
628 SmallVector<int, 16> newMask;
631 // Create a new mask for the new ShuffleVectorInst so that the new
632 // ShuffleVectorInst is equivalent to the original one.
633 for (unsigned i = 0; i < VWidth; ++i) {
636 // This element is an undef value.
638 } else if (Mask[i] < (int)LHSWidth) {
639 // This element is from left hand side vector operand.
641 // If LHS is going to be replaced (case 1, 2, or 4), calculate the
642 // new mask value for the element.
644 eltMask = LHSMask[Mask[i]];
645 // If the value selected is an undef value, explicitly specify it
646 // with a -1 mask value.
647 if (eltMask >= (int)LHSOp0Width && isa<UndefValue>(LHSOp1))
653 // This element is from right hand side vector operand
655 // If the value selected is an undef value, explicitly specify it
656 // with a -1 mask value. (case 1)
657 if (isa<UndefValue>(RHS))
659 // If RHS is going to be replaced (case 3 or 4), calculate the
660 // new mask value for the element.
661 else if (newRHS != RHS) {
662 eltMask = RHSMask[Mask[i]-LHSWidth];
663 // If the value selected is an undef value, explicitly specify it
664 // with a -1 mask value.
665 if (eltMask >= (int)RHSOp0Width) {
666 assert(isa<UndefValue>(RHSShuffle->getOperand(1))
667 && "should have been check above");
672 eltMask = Mask[i]-LHSWidth;
674 // If LHS's width is changed, shift the mask value accordingly.
675 // If newRHS == NULL, i.e. LHSOp0 == RHSOp0, we want to remap any
676 // references to RHSOp0 to LHSOp0, so we don't need to shift the mask.
677 if (eltMask >= 0 && newRHS != NULL)
678 eltMask += newLHSWidth;
681 // Check if this could still be a splat.
683 if (SplatElt >= 0 && SplatElt != eltMask)
688 newMask.push_back(eltMask);
691 // If the result mask is equal to one of the original shuffle masks,
692 // or is a splat, do the replacement.
693 if (isSplat || newMask == LHSMask || newMask == RHSMask || newMask == Mask) {
694 SmallVector<Constant*, 16> Elts;
695 Type *Int32Ty = Type::getInt32Ty(SVI.getContext());
696 for (unsigned i = 0, e = newMask.size(); i != e; ++i) {
697 if (newMask[i] < 0) {
698 Elts.push_back(UndefValue::get(Int32Ty));
700 Elts.push_back(ConstantInt::get(Int32Ty, newMask[i]));
704 newRHS = UndefValue::get(newLHS->getType());
705 return new ShuffleVectorInst(newLHS, newRHS, ConstantVector::get(Elts));
708 return MadeChange ? &SVI : 0;