path: root/libyul/optimiser/FullInliner.cpp

/*
    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/Exceptions.h>

#include <libsolidity/inlineasm/AsmData.h>

#include <libdevcore/CommonData.h>
#include <libdevcore/Visitor.h>

#include <boost/range/adaptor/reversed.hpp>

using namespace std;
using namespace dev;
using namespace dev::yul;
using namespace dev::solidity;

FullInliner::FullInliner(Block& _ast):
    m_ast(_ast)
{
    assertThrow(m_ast.statements.size() >= 1, OptimizerException, "");
    assertThrow(m_ast.statements.front().type() == typeid(Block), OptimizerException, "");
    m_nameDispenser.m_usedNames = NameCollector(m_ast).names();

    for (size_t i = 1; i < m_ast.statements.size(); ++i)
    {
        assertThrow(m_ast.statements.at(i).type() == typeid(FunctionDefinition), OptimizerException, "");
        FunctionDefinition& fun = boost::get<FunctionDefinition>(m_ast.statements.at(i));
        m_functions[fun.name] = &fun;
    }
}

void FullInliner::run()
{
    assertThrow(m_ast.statements[0].type() == typeid(Block), OptimizerException, "");

    handleBlock("", boost::get<Block>(m_ast.statements[0]));
    for (auto const& fun: m_functions)
        handleBlock(fun.second->name, fun.second->body);
}

void FullInliner::handleBlock(string const& _currentFunctionName, Block& _block)
{
    InlineModifier{*this, m_nameDispenser, _currentFunctionName}(_block);
}

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)
        {
            // TODO: Insert good heuristic here. Perhaps implement that inside the driver.
            bool doInline = funCall->functionName.name != m_currentFunction;

            if (doInline)
                return performInline(_statement, *funCall);
        }
    }
    return {};
}

vector<Statement> InlineModifier::performInline(Statement& _statement, FunctionCall& _funCall)
{
    vector<Statement> newStatements;
    map<string, string> variableReplacements;

    FunctionDefinition& function = m_driver.function(_funCall.functionName.name);

    // helper function to create a new variable that is supposed to model
    // an existing variable.
    auto newVariable = [&](TypedName const& _existingVariable, Expression* _value) {
        string newName = m_nameDispenser.newName(function.name + "_" + _existingVariable.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;
}

string InlineModifier::newName(string const& _prefix)
{
    return m_nameDispenser.newName(_prefix);
}

Statement BodyCopier::operator()(VariableDeclaration const& _varDecl)
{
    for (auto const& var: _varDecl.variables)
        m_variableReplacements[var.name] = m_nameDispenser.newName(m_varNamePrefix + var.name);
    return ASTCopier::operator()(_varDecl);
}

Statement BodyCopier::operator()(FunctionDefinition const& _funDef)
{
    assertThrow(false, OptimizerException, "Function hoisting has to be done before function inlining.");
    return _funDef;
}

string BodyCopier::translateIdentifier(string const& _name)
{
    if (m_variableReplacements.count(_name))
        return m_variableReplacements.at(_name);
    else
        return _name;
}