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[InstCombine][AVX] VPERMILVAR to shuffle combine to use general aggregate elements. NFCI.

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Make use of Constant::getAggregateElement instead of checking constant types - first step towards adding support for UNDEF mask elements.

llvm-svn: 268158
This commit is contained in:
Simon Pilgrim 2016-04-30 07:23:30 +00:00
parent ca3f439f16
commit 895490c6cb
1 changed files with 20 additions and 18 deletions
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38
lib/Transforms/InstCombine/InstCombineCalls.cpp
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@ -639,28 +639,30 @@ static Value *simplifyX86pshufb(const IntrinsicInst &II,
/// Attempt to convert vpermilvar* to shufflevector if the mask is constant.
static Value *simplifyX86vpermilvar(const IntrinsicInst &II,
InstCombiner::BuilderTy &Builder) {
Value *V = II.getArgOperand(1);
Constant *V = dyn_cast<Constant>(II.getArgOperand(1));
if (!V)
return nullptr;
unsigned Size = cast<VectorType>(V->getType())->getNumElements();
assert(Size == 8 || Size == 4 || Size == 2);
uint32_t Indexes[8];
if (auto C = dyn_cast<ConstantDataVector>(V)) {
// The intrinsics only read one or two bits, clear the rest.
for (unsigned I = 0; I < Size; ++I) {
uint32_t Index = C->getElementAsInteger(I) & 0x3;
// The PD variants uses bit 1 to select per-lane element index, so
// shift down to convert to generic shuffle mask index.
if (II.getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd ||
II.getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd_256)
Index >>= 1;
Indexes[I] = Index;
}
} else if (isa<ConstantAggregateZero>(V)) {
for (unsigned I = 0; I < Size; ++I)
Indexes[I] = 0;
} else {
return nullptr;
// Initialize the resulting shuffle mask to all zeroes.
uint32_t Indexes[8] = { 0 };
// The intrinsics only read one or two bits, clear the rest.
for (unsigned I = 0; I < Size; ++I) {
Constant *COp = V->getAggregateElement(I);
if (!COp || !isa<ConstantInt>(COp))
return nullptr;
int32_t Index = cast<ConstantInt>(COp)->getValue().getZExtValue() & 0x3;
// The PD variants uses bit 1 to select per-lane element index, so
// shift down to convert to generic shuffle mask index.
if (II.getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd ||
II.getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd_256)
Index >>= 1;
Indexes[I] = Index;
}
// The _256 variants are a bit trickier since the mask bits always index