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[X86] Remove apparently unneeded code from combineVSZext. 

No lit tests fail with this code removed.

This is a pre-commit for D54346.

llvm-svn: 346590
This commit is contained in:
Craig Topper 2018-11-10 17:44:28 +00:00
parent d3ca710ec9
commit 7956a256e9
1 changed files with 0 additions and 50 deletions
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50
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -40097,56 +40097,6 @@ static SDValue combineVSZext(SDNode *N, SelectionDAG &DAG,
return getConstVector(Vals, Undefs, VT, DAG, DL);
}
// (vzext (bitcast (vzext (x)) -> (vzext x)
// TODO: (vsext (bitcast (vsext (x)) -> (vsext x)
SDValue V = peekThroughBitcasts(Op);
if (Opcode == X86ISD::VZEXT && V != Op && V.getOpcode() == X86ISD::VZEXT) {
MVT InnerVT = V.getSimpleValueType();
MVT InnerEltVT = InnerVT.getVectorElementType();
// If the element sizes match exactly, we can just do one larger vzext. This
// is always an exact type match as vzext operates on integer types.
if (OpEltVT == InnerEltVT) {
assert(OpVT == InnerVT && "Types must match for vzext!");
return DAG.getNode(X86ISD::VZEXT, DL, VT, V.getOperand(0));
}
// The only other way we can combine them is if only a single element of the
// inner vzext is used in the input to the outer vzext.
if (InnerEltVT.getSizeInBits() < InputBits)
return SDValue();
// In this case, the inner vzext is completely dead because we're going to
// only look at bits inside of the low element. Just do the outer vzext on
// a bitcast of the input to the inner.
return DAG.getNode(X86ISD::VZEXT, DL, VT, DAG.getBitcast(OpVT, V));
}
// Check if we can bypass extracting and re-inserting an element of an input
// vector. Essentially:
// (bitcast (sclr2vec (ext_vec_elt x))) -> (bitcast x)
// TODO: Add X86ISD::VSEXT support
if (Opcode == X86ISD::VZEXT &&
V.getOpcode() == ISD::SCALAR_TO_VECTOR &&
V.getOperand(0).getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
V.getOperand(0).getSimpleValueType().getSizeInBits() == InputBits) {
SDValue ExtractedV = V.getOperand(0);
SDValue OrigV = ExtractedV.getOperand(0);
if (isNullConstant(ExtractedV.getOperand(1))) {
MVT OrigVT = OrigV.getSimpleValueType();
// Extract a subvector if necessary...
if (OrigVT.getSizeInBits() > OpVT.getSizeInBits()) {
int Ratio = OrigVT.getSizeInBits() / OpVT.getSizeInBits();
OrigVT = MVT::getVectorVT(OrigVT.getVectorElementType(),
OrigVT.getVectorNumElements() / Ratio);
OrigV = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, OrigVT, OrigV,
DAG.getIntPtrConstant(0, DL));
}
Op = DAG.getBitcast(OpVT, OrigV);
return DAG.getNode(X86ISD::VZEXT, DL, VT, Op);
}
}
return SDValue();
}