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[InstCombine] simplify code for inserts -> splat; NFC 

llvm-svn: 364441
This commit is contained in:
Sanjay Patel 2019-06-26 15:52:59 +00:00
parent 68ea5fee21
commit 71ad22707c
1 changed files with 17 additions and 25 deletions
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42
llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
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@ -662,18 +662,17 @@ static bool isShuffleEquivalentToSelect(ShuffleVectorInst &Shuf) {
return true;
}
// Turn a chain of inserts that splats a value into a canonical insert + shuffle
// splat. That is:
// insertelt(insertelt(insertelt(insertelt X, %k, 0), %k, 1), %k, 2) ... ->
// shufflevector(insertelt(X, %k, 0), undef, zero)
static Instruction *foldInsSequenceIntoBroadcast(InsertElementInst &InsElt) {
// We are interested in the last insert in a chain. So, if this insert
// has a single user, and that user is an insert, bail.
/// Turn a chain of inserts that splats a value into an insert + shuffle:
/// insertelt(insertelt(insertelt(insertelt X, %k, 0), %k, 1), %k, 2) ... ->
/// shufflevector(insertelt(X, %k, 0), undef, zero)
static Instruction *foldInsSequenceIntoSplat(InsertElementInst &InsElt) {
// We are interested in the last insert in a chain. So if this insert has a
// single user and that user is an insert, bail.
if (InsElt.hasOneUse() && isa<InsertElementInst>(InsElt.user_back()))
return nullptr;
VectorType *VT = cast<VectorType>(InsElt.getType());
int NumElements = VT->getNumElements();
auto *VecTy = cast<VectorType>(InsElt.getType());
unsigned NumElements = VecTy->getNumElements();
// Do not try to do this for a one-element vector, since that's a nop,
// and will cause an inf-loop.
@ -709,20 +708,15 @@ static Instruction *foldInsSequenceIntoBroadcast(InsertElementInst &InsElt) {
if (llvm::any_of(ElementPresent, [](bool Present) { return !Present; }))
return nullptr;
// All right, create the insert + shuffle.
Instruction *InsertFirst;
if (cast<ConstantInt>(FirstIE->getOperand(2))->isZero())
InsertFirst = FirstIE;
else
InsertFirst = InsertElementInst::Create(
UndefValue::get(VT), SplatVal,
ConstantInt::get(Type::getInt32Ty(InsElt.getContext()), 0),
"", &InsElt);
// Create the insert + shuffle.
Type *Int32Ty = Type::getInt32Ty(InsElt.getContext());
UndefValue *UndefVec = UndefValue::get(VecTy);
Constant *Zero = ConstantInt::get(Int32Ty, 0);
if (!cast<ConstantInt>(FirstIE->getOperand(2))->isZero())
FirstIE = InsertElementInst::Create(UndefVec, SplatVal, Zero, "", &InsElt);
Constant *ZeroMask = ConstantAggregateZero::get(
VectorType::get(Type::getInt32Ty(InsElt.getContext()), NumElements));
return new ShuffleVectorInst(InsertFirst, UndefValue::get(VT), ZeroMask);
Constant *ZeroMask = ConstantVector::getSplat(NumElements, Zero);
return new ShuffleVectorInst(FirstIE, UndefVec, ZeroMask);
}
/// If we have an insertelement instruction feeding into another insertelement
@ -940,9 +934,7 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
if (Instruction *NewInsElt = hoistInsEltConst(IE, Builder))
return NewInsElt;
// Turn a sequence of inserts that broadcasts a scalar into a single
// insert + shufflevector.
if (Instruction *Broadcast = foldInsSequenceIntoBroadcast(IE))
if (Instruction *Broadcast = foldInsSequenceIntoSplat(IE))
return Broadcast;
return nullptr;