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Optimize right shifts as clean (#6981)

This commit is contained in:
Geza Lore 2026-02-01 13:12:18 +00:00 committed by GitHub
parent ca17904a62
commit 5e5dcdbdbd
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2 changed files with 6 additions and 6 deletions
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8
include/verilated_funcs.h
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@ -1976,19 +1976,19 @@ static inline QData VL_SHIFTL_QQW(int obits, int, int rbits, QData lhs,
// expression. Thus consider this when optimizing. (And perhaps have 2 funcs?)
static inline IData VL_SHIFTR_III(int obits, int, int, IData lhs, IData rhs) VL_PURE {
if (VL_UNLIKELY(rhs >= VL_IDATASIZE)) return 0;
return lhs >> rhs; // Small is common so assumed not clean
return lhs >> rhs;
}
static inline IData VL_SHIFTR_IIQ(int obits, int, int, IData lhs, QData rhs) VL_PURE {
if (VL_UNLIKELY(rhs >= VL_IDATASIZE)) return 0;
return VL_CLEAN_QQ(obits, obits, lhs >> rhs);
return lhs >> rhs;
}
static inline QData VL_SHIFTR_QQI(int obits, int, int, QData lhs, IData rhs) VL_PURE {
if (VL_UNLIKELY(rhs >= VL_QUADSIZE)) return 0;
return lhs >> rhs; // Small is common so assumed not clean
return lhs >> rhs;
}
static inline QData VL_SHIFTR_QQQ(int obits, int, int, QData lhs, QData rhs) VL_PURE {
if (VL_UNLIKELY(rhs >= VL_QUADSIZE)) return 0;
return VL_CLEAN_QQ(obits, obits, lhs >> rhs);
return lhs >> rhs;
}
static inline WDataOutP VL_SHIFTR_WWI(int obits, int, int, WDataOutP owp, WDataInP const lwp,
IData rd) VL_MT_SAFE {

4
src/V3AstNodeExpr.h
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@ -3688,7 +3688,7 @@ public:
string emitSimpleOperator() override {
return (rhsp()->isWide() || rhsp()->isQuad()) ? "" : ">>";
}
bool cleanOut() const override { return false; }
bool cleanOut() const override { return true; }
bool cleanLhs() const override { return true; }
bool cleanRhs() const override { return true; }
// LHS size might be > output size, so don't want to force size
@ -3710,7 +3710,7 @@ public:
string emitVerilog() override { return "%k(%l %f>> %r)"; }
string emitC() override { return "VL_SHIFTR_%nq%lq%rq(%nw,%lw,%rw, %P, %li, %ri)"; }
string emitSimpleOperator() override { return ""; }
bool cleanOut() const override { return false; }
bool cleanOut() const override { return true; }
bool cleanLhs() const override { return true; }
bool cleanRhs() const override { return true; }
// LHS size might be > output size, so don't want to force size