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V3DfgPasses: Optimize mux with UInt To OneHot (#6822)

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Signed-off-by: Yangyu Chen <[email protected]>
This commit is contained in:
Yangyu Chen
2025-12-17 12:07:21 -05:00
committed by GitHub
parent 6f43ad8607
commit bd38775ad2
3 changed files with 150 additions and 1 deletions
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src/V3DfgPasses.cpp
+12
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@@ -173,6 +173,18 @@ void V3DfgPasses::binToOneHot(DfgGraph& dfg, V3DfgBinToOneHotContext& ctx) {
if (!widthOk(srcp) || !useOk(redOrp, true)) continue;
val = 0;
inv = true;
} else if (DfgSel* const selp = vtx.cast<DfgSel>()) {
// Special case: Sel(ShiftL(1, src),lsb,width=1)
if (selp->width() != 1) continue;
DfgShiftL* const shiftLp = selp->fromp()->cast<DfgShiftL>();
if (!shiftLp) continue;
DfgConst* const constp = shiftLp->lhsp()->cast<DfgConst>();
if (!constp || !useOk(selp, false)) continue;
if (!constp->hasValue(1)) continue;
srcp = shiftLp->rhsp();
if (!widthOk(srcp)) continue;
val = selp->lsb();
inv = false;
} else {
// Not a comparison-like vertex
continue;