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[X86] checkBitcastSrcVectorSize - early return when reach to MaxRecursionDepth. #130226

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Merged
merged 2 commits into from
Mar 10, 2025
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[X86] checkBitcastSrcVectorSize - early return when reach to MaxRecursionDepth. #130226

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4574283
[X86] Fix duplicated compute in recursive search.
haonanya1 Mar 7, 2025
b5aeeee
Add a recursive depth limit.
haonanya1 Mar 10, 2025
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28 changes: 18 additions & 10 deletions llvm/lib/Target/X86/X86ISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -44746,7 +44746,10 @@ bool X86TargetLowering::isSplatValueForTargetNode(SDValue Op,
// Helper to peek through bitops/trunc/setcc to determine size of source vector.
// Allows combineBitcastvxi1 to determine what size vector generated a <X x i1>.
static bool checkBitcastSrcVectorSize(SDValue Src, unsigned Size,
bool AllowTruncate) {
bool AllowTruncate, unsigned Depth) {
// Limit recursion.
if (Depth >= SelectionDAG::MaxRecursionDepth)
return false;
switch (Src.getOpcode()) {
case ISD::TRUNCATE:
if (!AllowTruncate)
Expand All @@ -44755,17 +44758,22 @@ static bool checkBitcastSrcVectorSize(SDValue Src, unsigned Size,
case ISD::SETCC:
return Src.getOperand(0).getValueSizeInBits() == Size;
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How about define a bool Result = false; to avoid repeat BitcastSrcVectorSizeMap[Tp] =?

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@haonanya1 haonanya1 Mar 10, 2025 •
edited
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Update pr to Early return when reach to MaxRecursionDepth. It's same as current other implementation, such as SimplifyMultipleUseDemandedBits, matchIndexRecursively and so on.

case ISD::FREEZE:
return checkBitcastSrcVectorSize(Src.getOperand(0), Size, AllowTruncate);
return checkBitcastSrcVectorSize(Src.getOperand(0), Size, AllowTruncate,
Depth + 1);
case ISD::AND:
case ISD::XOR:
case ISD::OR:
return checkBitcastSrcVectorSize(Src.getOperand(0), Size, AllowTruncate) &&
checkBitcastSrcVectorSize(Src.getOperand(1), Size, AllowTruncate);
return checkBitcastSrcVectorSize(Src.getOperand(0), Size, AllowTruncate,
Depth + 1) &&
checkBitcastSrcVectorSize(Src.getOperand(1), Size, AllowTruncate,
Depth + 1);
case ISD::SELECT:
case ISD::VSELECT:
return Src.getOperand(0).getScalarValueSizeInBits() == 1 &&
checkBitcastSrcVectorSize(Src.getOperand(1), Size, AllowTruncate) &&
checkBitcastSrcVectorSize(Src.getOperand(2), Size, AllowTruncate);
checkBitcastSrcVectorSize(Src.getOperand(1), Size, AllowTruncate,
Depth + 1) &&
checkBitcastSrcVectorSize(Src.getOperand(2), Size, AllowTruncate,
Depth + 1);
case ISD::BUILD_VECTOR:
return ISD::isBuildVectorAllZeros(Src.getNode()) ||
ISD::isBuildVectorAllOnes(Src.getNode());
Expand Down Expand Up @@ -44936,7 +44944,7 @@ static SDValue combineBitcastvxi1(SelectionDAG &DAG, EVT VT, SDValue Src,
// For cases such as (i4 bitcast (v4i1 setcc v4i64 v1, v2))
// sign-extend to a 256-bit operation to avoid truncation.
if (Subtarget.hasAVX() &&
checkBitcastSrcVectorSize(Src, 256, Subtarget.hasAVX2())) {
checkBitcastSrcVectorSize(Src, 256, Subtarget.hasAVX2(), 0)) {
SExtVT = MVT::v4i64;
PropagateSExt = true;
}
Expand All @@ -44948,8 +44956,8 @@ static SDValue combineBitcastvxi1(SelectionDAG &DAG, EVT VT, SDValue Src,
// If the setcc operand is 128-bit, prefer sign-extending to 128-bit over
// 256-bit because the shuffle is cheaper than sign extending the result of
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DenseMap?

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@haonanya1 haonanya1 Mar 10, 2025 •
edited
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Update pr to Early return when reach to MaxRecursionDepth. It's same as current other implementation, such as SimplifyMultipleUseDemandedBits, matchIndexRecursively and so on.

// the compare.
if (Subtarget.hasAVX() && (checkBitcastSrcVectorSize(Src, 256, true) ||
checkBitcastSrcVectorSize(Src, 512, true))) {
if (Subtarget.hasAVX() && (checkBitcastSrcVectorSize(Src, 256, true, 0) ||
checkBitcastSrcVectorSize(Src, 512, true, 0))) {
SExtVT = MVT::v8i32;
PropagateSExt = true;
}
Expand All @@ -44974,7 +44982,7 @@ static SDValue combineBitcastvxi1(SelectionDAG &DAG, EVT VT, SDValue Src,
break;
}
// Split if this is a <64 x i8> comparison result.
if (checkBitcastSrcVectorSize(Src, 512, false)) {
if (checkBitcastSrcVectorSize(Src, 512, false, 0)) {
SExtVT = MVT::v64i8;
break;
}
Expand Down