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[SDAG] Handle insert_subvector in isKnownNeverNaN #131989

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Merged
tclin914 merged 7 commits into from
Apr 21, 2025
Merged

[SDAG] Handle insert_subvector in isKnownNeverNaN #131989

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7e13154
[SDAG] Pre-commit
tclin914 Mar 19, 2025
6846661
[SDAG] Handle insert_subvector in isKnownNeverNaN
tclin914 Mar 19, 2025
620794b
Adjust DemandedElts
tclin914 Apr 21, 2025
b74ac56
Address RKSimon's comments
tclin914 Apr 21, 2025
89759f4
Add braces and remove else
tclin914 Apr 21, 2025
d6ffb12
Remove else
tclin914 Apr 21, 2025
58854e6
Refine the style to avoid if-else chain.
tclin914 Apr 21, 2025
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36 changes: 19 additions & 17 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5758,23 +5758,25 @@ bool SelectionDAG::isKnownNeverNaN(SDValue Op, const APInt &DemandedElts,
EVT BaseVectorVT = BaseVector.getValueType();
if (BaseVectorVT.isFixedLengthVector()) {
unsigned Idx = Op.getConstantOperandVal(2);
unsigned NumBaseVectorElts = BaseVectorVT.getVectorNumElements();
unsigned NumSubVectorElts =
SubVector.getValueType().getVectorNumElements();

// Clear the bits at the position where the subvector will be inserted.
APInt DemandedMask = APInt::getAllOnes(NumSubVectorElts)
.zext(NumBaseVectorElts)
.shl(Idx)
.reverseBits();
APInt DemandedSrcElts = DemandedElts & DemandedMask;

// If DemandedSrcElts is zero, we only need to check that the subvector is
// never NaN.
if (DemandedSrcElts.isZero())
return isKnownNeverNaN(SubVector, SNaN, Depth + 1);
return isKnownNeverNaN(BaseVector, DemandedSrcElts, SNaN, Depth + 1) &&
isKnownNeverNaN(SubVector, SNaN, Depth + 1);
unsigned NumBaseElts = BaseVectorVT.getVectorNumElements();
unsigned NumSubElts = SubVector.getValueType().getVectorNumElements();

// Clear/Extract the bits at the position where the subvector will be
// inserted.
APInt DemandedMask =
APInt::getBitsSet(NumBaseElts, Idx, Idx + NumSubElts);
APInt DemandedSrcElts = DemandedElts & ~DemandedMask;
APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);

if (!DemandedSrcElts.isZero() && !DemandedSubElts.isZero())
return isKnownNeverNaN(BaseVector, DemandedSrcElts, SNaN, Depth + 1) &&
isKnownNeverNaN(SubVector, DemandedSubElts, SNaN, Depth + 1);
else if (!DemandedSrcElts.isZero())
return isKnownNeverNaN(BaseVector, DemandedSrcElts, SNaN, Depth + 1);
else if (!DemandedSubElts.isZero())
return isKnownNeverNaN(SubVector, DemandedSubElts, SNaN, Depth + 1);
else
return true;
}
return isKnownNeverNaN(BaseVector, SNaN, Depth + 1) &&
isKnownNeverNaN(SubVector, SNaN, Depth + 1);
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