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/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* Optimiser component that performs function inlining for arbitrary functions.
*/
#include <libyul/optimiser/FullInliner.h>
#include <libyul/optimiser/ASTCopier.h>
#include <libyul/optimiser/ASTWalker.h>
#include <libyul/optimiser/NameCollector.h>
#include <libyul/optimiser/Utilities.h>
#include <libyul/optimiser/Metrics.h>
#include <libyul/optimiser/SSAValueTracker.h>
#include <libyul/Exceptions.h>
#include <libyul/AsmData.h>
#include <libdevcore/CommonData.h>
#include <libdevcore/Visitor.h>
#include <boost/range/adaptor/reversed.hpp>
using namespace std;
using namespace dev;
using namespace yul;
using namespace dev::solidity;
FullInliner::FullInliner(Block& _ast, NameDispenser& _dispenser):
m_ast(_ast), m_nameDispenser(_dispenser)
{
// Determine constants
SSAValueTracker tracker;
tracker(m_ast);
for (auto const& ssaValue: tracker.values())
if (ssaValue.second && ssaValue.second->type() == typeid(Literal))
m_constants.emplace(ssaValue.first);
map<YulString, size_t> references = ReferencesCounter::countReferences(m_ast);
for (auto& statement: m_ast.statements)
{
if (statement.type() != typeid(FunctionDefinition))
continue;
FunctionDefinition& fun = boost::get<FunctionDefinition>(statement);
m_functions[fun.name] = &fun;
// Always inline functions that are only called once.
if (references[fun.name] == 1)
m_alwaysInline.emplace(fun.name);
updateCodeSize(fun);
}
}
void FullInliner::run()
{
for (auto& statement: m_ast.statements)
if (statement.type() == typeid(Block))
handleBlock({}, boost::get<Block>(statement));
// TODO it might be good to determine a visiting order:
// first handle functions that are called from many places.
for (auto const& fun: m_functions)
{
handleBlock(fun.second->name, fun.second->body);
updateCodeSize(*fun.second);
}
}
void FullInliner::updateCodeSize(FunctionDefinition& fun)
{
m_functionSizes[fun.name] = CodeSize::codeSize(fun.body);
}
void FullInliner::handleBlock(YulString _currentFunctionName, Block& _block)
{
InlineModifier{*this, m_nameDispenser, _currentFunctionName}(_block);
}
bool FullInliner::shallInline(FunctionCall const& _funCall, YulString _callSite)
{
// No recursive inlining
if (_funCall.functionName.name == _callSite)
return false;
FunctionDefinition* calledFunction = function(_funCall.functionName.name);
if (!calledFunction)
return false;
if (m_alwaysInline.count(calledFunction->name))
return true;
// Constant arguments might provide a means for further optimization, so they cause a bonus.
bool constantArg = false;
for (auto const& argument: _funCall.arguments)
if (argument.type() == typeid(Literal) || (
argument.type() == typeid(Identifier) &&
m_constants.count(boost::get<Identifier>(argument).name)
))
{
constantArg = true;
break;
}
size_t size = m_functionSizes.at(calledFunction->name);
return (size < 10 || (constantArg && size < 50));
}
void InlineModifier::operator()(Block& _block)
{
function<boost::optional<vector<Statement>>(Statement&)> f = [&](Statement& _statement) -> boost::optional<vector<Statement>> {
visit(_statement);
return tryInlineStatement(_statement);
};
iterateReplacing(_block.statements, f);
}
boost::optional<vector<Statement>> InlineModifier::tryInlineStatement(Statement& _statement)
{
// Only inline for expression statements, assignments and variable declarations.
Expression* e = boost::apply_visitor(GenericFallbackReturnsVisitor<Expression*, ExpressionStatement, Assignment, VariableDeclaration>(
[](ExpressionStatement& _s) { return &_s.expression; },
[](Assignment& _s) { return _s.value.get(); },
[](VariableDeclaration& _s) { return _s.value.get(); }
), _statement);
if (e)
{
// Only inline direct function calls.
FunctionCall* funCall = boost::apply_visitor(GenericFallbackReturnsVisitor<FunctionCall*, FunctionCall&>(
[](FunctionCall& _e) { return &_e; }
), *e);
if (funCall && m_driver.shallInline(*funCall, m_currentFunction))
return performInline(_statement, *funCall);
}
return {};
}
vector<Statement> InlineModifier::performInline(Statement& _statement, FunctionCall& _funCall)
{
vector<Statement> newStatements;
map<YulString, YulString> variableReplacements;
FunctionDefinition* function = m_driver.function(_funCall.functionName.name);
assertThrow(!!function, OptimizerException, "Attempt to inline invalid function.");
// helper function to create a new variable that is supposed to model
// an existing variable.
auto newVariable = [&](TypedName const& _existingVariable, Expression* _value) {
YulString newName = m_nameDispenser.newName(_existingVariable.name, function->name);
variableReplacements[_existingVariable.name] = newName;
VariableDeclaration varDecl{_funCall.location, {{_funCall.location, newName, _existingVariable.type}}, {}};
if (_value)
varDecl.value = make_shared<Expression>(std::move(*_value));
newStatements.emplace_back(std::move(varDecl));
};
for (size_t i = 0; i < _funCall.arguments.size(); ++i)
newVariable(function->parameters[i], &_funCall.arguments[i]);
for (auto const& var: function->returnVariables)
newVariable(var, nullptr);
Statement newBody = BodyCopier(m_nameDispenser, function->name, variableReplacements)(function->body);
newStatements += std::move(boost::get<Block>(newBody).statements);
boost::apply_visitor(GenericFallbackVisitor<Assignment, VariableDeclaration>{
[&](Assignment& _assignment)
{
for (size_t i = 0; i < _assignment.variableNames.size(); ++i)
newStatements.emplace_back(Assignment{
_assignment.location,
{_assignment.variableNames[i]},
make_shared<Expression>(Identifier{
_assignment.location,
variableReplacements.at(function->returnVariables[i].name)
})
});
},
[&](VariableDeclaration& _varDecl)
{
for (size_t i = 0; i < _varDecl.variables.size(); ++i)
newStatements.emplace_back(VariableDeclaration{
_varDecl.location,
{std::move(_varDecl.variables[i])},
make_shared<Expression>(Identifier{
_varDecl.location,
variableReplacements.at(function->returnVariables[i].name)
})
});
}
// nothing to be done for expression statement
}, _statement);
return newStatements;
}
Statement BodyCopier::operator()(VariableDeclaration const& _varDecl)
{
for (auto const& var: _varDecl.variables)
m_variableReplacements[var.name] = m_nameDispenser.newName(var.name, m_varNamePrefix);
return ASTCopier::operator()(_varDecl);
}
Statement BodyCopier::operator()(FunctionDefinition const& _funDef)
{
assertThrow(false, OptimizerException, "Function hoisting has to be done before function inlining.");
return _funDef;
}
YulString BodyCopier::translateIdentifier(YulString _name)
{
if (m_variableReplacements.count(_name))
return m_variableReplacements.at(_name);
else
return _name;
}
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