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[X86][SSE] createVariablePermute - create index scaling helper. NFCI. 

This will help in some future changes for custom lowering.

llvm-svn: 327217
This commit is contained in:
Simon Pilgrim 2018-03-10 18:12:35 +00:00
parent a1da86b224
commit d9dc114e2f
1 changed files with 26 additions and 23 deletions
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49
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -7934,6 +7934,30 @@ SDValue createVariablePermute(MVT VT, SDValue SrcVec, SDValue IndicesVec,
DAG.getNode(ISD::INSERT_SUBVECTOR, SDLoc(SrcVec), VT, DAG.getUNDEF(VT),
SrcVec, DAG.getIntPtrConstant(0, SDLoc(SrcVec)));
auto ScaleIndices = [&DAG](SDValue Idx, uint64_t Scale) {
assert(isPowerOf2_64(Scale) && "Illegal variable permute shuffle scale");
EVT SrcVT = Idx.getValueType();
unsigned NumDstBits = SrcVT.getScalarSizeInBits() / Scale;
uint64_t IndexScale = 0;
uint64_t IndexOffset = 0;
// If we're scaling a smaller permute op, then we need to repeat the
// indices, scaling and offsetting them as well.
// e.g. v4i32 -> v16i8 (Scale = 4)
// IndexScale = v4i32 Splat(4 << 24 | 4 << 16 | 4 << 8 | 4)
// IndexOffset = v4i32 Splat(3 << 24 | 2 << 16 | 1 << 8 | 0)
for (uint64_t i = 0; i != Scale; ++i) {
IndexScale |= Scale << (i * NumDstBits);
IndexOffset |= i << (i * NumDstBits);
}
Idx = DAG.getNode(ISD::MUL, SDLoc(Idx), SrcVT, Idx,
DAG.getConstant(IndexScale, SDLoc(Idx), SrcVT));
Idx = DAG.getNode(ISD::ADD, SDLoc(Idx), SrcVT, Idx,
DAG.getConstant(IndexOffset, SDLoc(Idx), SrcVT));
return Idx;
};
unsigned Opcode = 0;
switch (VT.SimpleTy) {
default:
@ -8025,29 +8049,8 @@ SDValue createVariablePermute(MVT VT, SDValue SrcVec, SDValue IndicesVec,
"Illegal variable permute shuffle type");
uint64_t Scale = VT.getScalarSizeInBits() / ShuffleVT.getScalarSizeInBits();
if (Scale > 1) {
assert(isPowerOf2_64(Scale) && "Illegal variable permute shuffle scale");
unsigned ShuffleBits = ShuffleVT.getScalarSizeInBits();
uint64_t IndexScale = 0;
uint64_t IndexOffset = 0;
// If we're scaling a smaller permute op, then we need to repeat the
// indices, scaling and offsetting them as well.
// e.g. v4i32 -> v16i8 (Scale = 4)
// IndexScale = v4i32 Splat(4 << 24 | 4 << 16 | 4 << 8 | 4)
// IndexOffset = v4i32 Splat(3 << 24 | 2 << 16 | 1 << 8 | 0)
for (uint64_t i = 0; i != Scale; ++i) {
IndexScale |= Scale << (i * ShuffleBits);
IndexOffset |= i << (i * ShuffleBits);
}
IndicesVec =
DAG.getNode(ISD::MUL, SDLoc(IndicesVec), IndicesVT, IndicesVec,
DAG.getConstant(IndexScale, SDLoc(IndicesVec), IndicesVT));
IndicesVec =
DAG.getNode(ISD::ADD, SDLoc(IndicesVec), IndicesVT, IndicesVec,
DAG.getConstant(IndexOffset, SDLoc(IndicesVec), IndicesVT));
}
if (Scale > 1)
IndicesVec = ScaleIndices(IndicesVec, Scale);
EVT ShuffleIdxVT = EVT(ShuffleVT).changeVectorElementTypeToInteger();
IndicesVec = DAG.getBitcast(ShuffleIdxVT, IndicesVec);