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[clang][bytecode] interp__builtin_ia32_pshuf - modulo lane index to allow reuse of PSHUFD/LW/HW mask decode. NFC #162006

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Merged
merged 1 commit into from
Oct 5, 2025
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[clang][bytecode] interp__builtin_ia32_pshuf - modulo lane index to allow reuse of PSHUFD/LW/HW mask decode. NFC #162006

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4 changes: 1 addition & 3 deletions clang/lib/AST/ByteCode/InterpBuiltin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2796,7 +2796,7 @@ static bool interp__builtin_ia32_pshuf(InterpState &S, CodePtr OpPC,
unsigned LaneBase = (Idx / LaneElts) * LaneElts;
unsigned LaneIdx = Idx % LaneElts;
unsigned SrcIdx = Idx;
unsigned Sel = (Ctl >> (2 * LaneIdx)) & 0x3;
unsigned Sel = (Ctl >> (2 * (LaneIdx & 0x3))) & 0x3;
if (ElemBits == 32) {
SrcIdx = LaneBase + Sel;
} else {
Expand All @@ -2805,8 +2805,6 @@ static bool interp__builtin_ia32_pshuf(InterpState &S, CodePtr OpPC,
if (!IsShufHW && !InHigh) {
SrcIdx = LaneBase + Sel;
} else if (IsShufHW && InHigh) {
unsigned Rel = LaneIdx - HalfSize;
Sel = (Ctl >> (2 * Rel)) & 0x3;
SrcIdx = LaneBase + HalfSize + Sel;
}
}
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