solidity/libyul/optimiser/NameSimplifier.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/>.
*/

#include <libyul/optimiser/NameSimplifier.h>
#include <libyul/optimiser/NameCollector.h>
#include <libyul/AsmData.h>
#include <libyul/Dialect.h>
#include <libyul/optimiser/OptimizerUtilities.h>

#include <libsolutil/CommonData.h>

#include <regex>

using namespace solidity::yul;
using namespace std;

NameSimplifier::NameSimplifier(
	OptimiserStepContext& _context,
	Block const& _ast
):
	m_context(_context),
	m_usedNames(_context.reservedIdentifiers)
{
	for (YulString name: m_usedNames)
		m_translations[name] = name;

	set<YulString> allNames = NameCollector(_ast).names();
	m_usedNames += allNames;
	for (YulString name: allNames)
		findSimplification(name);
}

void NameSimplifier::operator()(FunctionDefinition& _funDef)
{
	translate(_funDef.name);
	renameVariables(_funDef.parameters);
	renameVariables(_funDef.returnVariables);
	ASTModifier::operator()(_funDef);
}

void NameSimplifier::operator()(VariableDeclaration& _varDecl)
{
	renameVariables(_varDecl.variables);
	ASTModifier::operator()(_varDecl);
}

void NameSimplifier::renameVariables(vector<TypedName>& _variables)
{
	for (TypedName& typedName: _variables)
		translate(typedName.name);
}

void NameSimplifier::operator()(Identifier& _identifier)
{
	translate(_identifier.name);
}

void NameSimplifier::operator()(FunctionCall& _funCall)
{
	// The visitor on its own does not visit the function name.
	if (!m_context.dialect.builtin(_funCall.functionName.name))
		(*this)(_funCall.functionName);
	ASTModifier::operator()(_funCall);
}

void NameSimplifier::findSimplification(YulString _name)
{
	if (m_translations.count(_name))
		return;

	string name = _name.str();

	static auto replacements = vector<pair<regex, string>>{
		{regex("_\\$\\d+"), ""}, // removes AST IDs
		{regex("(abi_..code.*)_to_.*"), "$1"}, // removes _to... for abi functions
		{regex("(stringliteral_[0-9a-f][0-9a-f][0-9a-f][0-9a-f])[0-9a-f]*"), "$1"}, // shorten string literal
		{regex("tuple_t_"), ""},
		{regex("_memory_ptr"), ""},
		{regex("_calldata_ptr"), "_calldata"},
		{regex("_fromStack"), ""},
		{regex("_storage_storage"), "_storage"},
		{regex("_memory_memory"), "_memory"},
		{regex("t_contract\\$_([^_]*)_"), "$1_"},
		{regex("index_access_t_array"), "index_access"},
		{regex("[0-9]*_$"), ""}
	};
	for (auto const& [pattern, substitute]: replacements)
	{
		string candidate = regex_replace(name, pattern, substitute);
		if (
			!isRestrictedIdentifier(m_context.dialect, YulString(candidate)) &&
			!m_usedNames.count(YulString(candidate))
		)
			name = candidate;
	}
	if (name != _name.str())
	{
		m_usedNames.insert(YulString(name));
		m_translations[_name] = YulString(name);
	}
}

void NameSimplifier::translate(YulString& _name)
{
	auto it = m_translations.find(_name);
	if (it != m_translations.end())
		_name = it->second;
}