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[Yul] ExpressionJoiner: code cleanup

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* ensure public API is only containing `run(Block&)`, all the rest is private API / implementation details
* adding some comments to class data members to quicker understand their meaning
* eliminate unnecessary `operator()(If&)` as it's not changing default behaviour of `ASTModifier`
* simplify readability of `visit(Expression&)`'s impl, also moving assert's into "isLatestStatementVarDeclOf", as this one is already ensuring exactly that.
* ctor impl's use of ReferenceCounter use shortened.
* renamed and improved `isLatestStatementVarDeclOf` to better match its meaning (especially since it's only used once)
This commit is contained in:
Christian Parpart 2018-10-26 13:38:53 +02:00
parent 41375b5d79
commit 1264290d57
2 changed files with 20 additions and 36 deletions
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30
libyul/optimiser/ExpressionJoiner.cpp
View File

@ -46,20 +46,6 @@ void ExpressionJoiner::operator()(FunctionCall& _funCall)
handleArguments(_funCall.arguments);
}
void ExpressionJoiner::operator()(If& _if)
{
visit(*_if.condition);
(*this)(_if.body);
}
void ExpressionJoiner::operator()(Switch& _switch)
{
visit(*_switch.expression);
for (auto& _case: _switch.cases)
// Do not visit the case expression, nothing to join there.
(*this)(_case.body);
}
void ExpressionJoiner::operator()(Block& _block)
{
resetLatestStatementPointer();
@ -79,13 +65,11 @@ void ExpressionJoiner::visit(Expression& _e)
if (_e.type() == typeid(Identifier))
{
Identifier const& identifier = boost::get<Identifier>(_e);
if (isLatestStatementVarDeclOf(identifier) && m_references[identifier.name] == 1)
if (isLatestStatementVarDeclJoinable(identifier))
{
VariableDeclaration& varDecl = boost::get<VariableDeclaration>(*latestStatement());
assertThrow(varDecl.variables.size() == 1, OptimizerException, "");
assertThrow(varDecl.value, OptimizerException, "");
_e = std::move(*varDecl.value);
// Delete the variable declaration (also get the moved-from structure back into a sane state)
*latestStatement() = Block();
@ -103,9 +87,7 @@ void ExpressionJoiner::run(Block& _ast)
ExpressionJoiner::ExpressionJoiner(Block& _ast)
{
ReferencesCounter counter;
counter(_ast);
m_references = counter.references();
m_references = ReferencesCounter::countReferences(_ast);
}
void ExpressionJoiner::handleArguments(vector<Expression>& _arguments)
@ -154,7 +136,7 @@ Statement* ExpressionJoiner::latestStatement()
return &m_currentBlock->statements.at(m_latestStatementInBlock);
}
bool ExpressionJoiner::isLatestStatementVarDeclOf(Identifier const& _identifier)
bool ExpressionJoiner::isLatestStatementVarDeclJoinable(Identifier const& _identifier)
{
Statement const* statement = latestStatement();
if (!statement || statement->type() != typeid(VariableDeclaration))
@ -162,5 +144,7 @@ bool ExpressionJoiner::isLatestStatementVarDeclOf(Identifier const& _identifier)
VariableDeclaration const& varDecl = boost::get<VariableDeclaration>(*statement);
if (varDecl.variables.size() != 1 || !varDecl.value)
return false;
return varDecl.variables.at(0).name == _identifier.name;
assertThrow(varDecl.variables.size() == 1, OptimizerException, "");
assertThrow(varDecl.value, OptimizerException, "");
return varDecl.variables.at(0).name == _identifier.name && m_references[_identifier.name] == 1;
}

26
libyul/optimiser/ExpressionJoiner.h
View File

@ -73,29 +73,29 @@ class NameCollector;
class ExpressionJoiner: public ASTModifier
{
public:
virtual void operator()(FunctionalInstruction&) override;
virtual void operator()(FunctionCall&) override;
virtual void operator()(If&) override;
virtual void operator()(Switch&) override;
virtual void operator()(Block& _block) override;
using ASTModifier::visit;
virtual void visit(Expression& _e) override;
static void run(Block& _ast);
private:
explicit ExpressionJoiner(Block& _ast);
void operator()(Block& _block) override;
void operator()(FunctionalInstruction&) override;
void operator()(FunctionCall&) override;
using ASTModifier::visit;
void visit(Expression& _e) override;
void handleArguments(std::vector<Expression>& _arguments);
void decrementLatestStatementPointer();
void resetLatestStatementPointer();
Statement* latestStatement();
bool isLatestStatementVarDeclOf(Identifier const& _identifier);
bool isLatestStatementVarDeclJoinable(Identifier const& _identifier);
Block* m_currentBlock = nullptr;
size_t m_latestStatementInBlock = 0;
std::map<std::string, size_t> m_references;
private:
Block* m_currentBlock = nullptr; ///< Pointer to currently block holding the visiting statement.
size_t m_latestStatementInBlock = 0; ///< Offset to m_currentBlock's statements of the last visited statement.
std::map<std::string, size_t> m_references; ///< Holds reference counts to all variable declarations in current block.
};
}