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[X86] LowerStore - always split 512-bit concatenated stores #143426

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Jun 10, 2025
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12 changes: 5 additions & 7 deletions llvm/lib/Target/X86/X86ISelLowering.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -25549,14 +25549,12 @@ static SDValue LowerStore(SDValue Op, const X86Subtarget &Subtarget,
if (St->isTruncatingStore())
return SDValue();

// If this is a 256-bit store of concatenated ops, we are better off splitting
// that store into two 128-bit stores. This avoids spurious use of 256-bit ops
// and each half can execute independently. Some cores would split the op into
// halves anyway, so the concat (vinsertf128) is purely an extra op.
// If this is a 256/512-bit store of concatenated ops, we are better off
// splitting that store into two half-size stores. This avoids spurious use of
// concatenated ops and each half can execute independently. Some cores would
// split the op into halves anyway, so the concat is purely an extra op.
MVT StoreVT = StoredVal.getSimpleValueType();
if (StoreVT.is256BitVector() ||
((StoreVT == MVT::v32i16 || StoreVT == MVT::v64i8) &&
!Subtarget.hasBWI())) {
if (StoreVT.is256BitVector() || StoreVT.is512BitVector()) {
if (StoredVal.hasOneUse() && isFreeToSplitVector(StoredVal, DAG))
return splitVectorStore(St, DAG);
return SDValue();
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