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Consider return variables to be zero initially.

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This commit is contained in:
chriseth
2018-12-13 16:02:30 +01:00
parent 996bfb2a83
commit b11d413720
6 changed files with 79 additions and 36 deletions
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libyul/optimiser/SSAValueTracker.cpp
+11 -2
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@@ -33,12 +33,18 @@ void SSAValueTracker::operator()(Assignment const& _assignment)
m_values.erase(var.name);
}
void SSAValueTracker::operator()(FunctionDefinition const& _funDef)
{
for (auto const& var: _funDef.returnVariables)
setValue(var.name, nullptr);
ASTWalker::operator()(_funDef);
}
void SSAValueTracker::operator()(VariableDeclaration const& _varDecl)
{
static Expression const zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};
if (!_varDecl.value)
for (auto const& var: _varDecl.variables)
setValue(var.name, &zero);
setValue(var.name, nullptr);
else if (_varDecl.variables.size() == 1)
setValue(_varDecl.variables.front().name, _varDecl.value.get());
}
@@ -50,5 +56,8 @@ void SSAValueTracker::setValue(YulString _name, Expression const* _value)
OptimizerException,
"Source needs to be disambiguated."
);
static Expression const zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};
if (!_value)
_value = &zero;
m_values[_name] = _value;
}