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Simplify applying bitwise operators on sign extended values #1111

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Simplify applying bitwise operators on sign extended values #1111

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5d72e4c
Simplify zext/sext of bitwise operator
can-leh-emmtrix Nov 12, 2024
601acb3
zext is not emitted
can-leh-emmtrix Nov 12, 2024
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30 changes: 30 additions & 0 deletions smt/expr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1346,6 +1346,14 @@ expr expr::operator&(const expr &rhs) const {
if (isAllOnes() || rhs.isZero())
return rhs;

{
expr lhsVal, rhsVal;
if (isSignExt(lhsVal) && rhs.isSignExt(rhsVal) &&
lhsVal.bits() == rhsVal.bits()) {
return (lhsVal & rhsVal).sext(bits() - lhsVal.bits());
}
}

auto fold_extract = [](auto &a, auto &b) {
uint64_t n;
if (!a.isUInt(n) || n == 0 || n == numeric_limits<uint64_t>::max())
Expand Down Expand Up @@ -1391,6 +1399,14 @@ expr expr::operator|(const expr &rhs) const {
if (isZero() || rhs.isAllOnes())
return rhs;

{
expr lhsVal, rhsVal;
if (isSignExt(lhsVal) && rhs.isSignExt(rhsVal) &&
lhsVal.bits() == rhsVal.bits()) {
return (lhsVal | rhsVal).sext(bits() - lhsVal.bits());
}
}

if (bits() == 1) {
if (auto a = get_bool(*this);
a.isValid())
Expand All @@ -1409,6 +1425,15 @@ expr expr::operator^(const expr &rhs) const {
return bits() == 1 ? (rhs == 0).toBVBool() : ~rhs;
if (rhs.isAllOnes())
return bits() == 1 ? (*this == 0).toBVBool() : ~*this;

{
expr lhsVal, rhsVal;
if (isSignExt(lhsVal) && rhs.isSignExt(rhsVal) &&
lhsVal.bits() == rhsVal.bits()) {
return (lhsVal ^ rhsVal).sext(bits() - lhsVal.bits());
}
}

return binopc(Z3_mk_bvxor, operator^, Z3_OP_BXOR, isZero, alwaysFalse);
}

Expand All @@ -1426,6 +1451,11 @@ expr expr::operator!() const {
}

expr expr::operator~() const {
expr val;
if (isSignExt(val)) {
return (~val).sext(bits() - val.bits());
}

return unop_fold(Z3_mk_bvnot);
}

Expand Down