Yul: Adds optimizer pass to make variable names suffix-canonical.

libyul/optimiser/VarNameCleaner.cpp

@@ -0,0 +1,122 @@
+/*
+	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/VarNameCleaner.h>
+#include <libyul/AsmData.h>
+#include <libyul/Dialect.h>
+#include <algorithm>
+#include <cctype>
+#include <climits>
+#include <iterator>
+#include <string>
+#include <regex>
+
+using namespace yul;
+using namespace std;
+
+VarNameCleaner::VarNameCleaner(
+	Block const& _ast,
+	Dialect const& _dialect,
+	set<YulString> _blacklist
+):
+	m_dialect{_dialect},
+	m_blacklist{std::move(_blacklist)},
+	m_translatedNames{}
+{
+	for (auto const& statement: _ast.statements)
+		if (statement.type() == typeid(FunctionDefinition))
+			m_blacklist.insert(boost::get<FunctionDefinition>(statement).name);
+	m_usedNames = m_blacklist;
+}
+
+void VarNameCleaner::operator()(FunctionDefinition& _funDef)
+{
+	yulAssert(!m_insideFunction, "");
+	m_insideFunction = true;
+
+	set<YulString> globalUsedNames = std::move(m_usedNames);
+	m_usedNames = m_blacklist;
+	map<YulString, YulString> globalTranslatedNames;
+	swap(globalTranslatedNames, m_translatedNames);
+
+	renameVariables(_funDef.parameters);
+	renameVariables(_funDef.returnVariables);
+	ASTModifier::operator()(_funDef);
+
+	swap(globalUsedNames, m_usedNames);
+	swap(globalTranslatedNames, m_translatedNames);
+
+	m_insideFunction = false;
+}
+
+void VarNameCleaner::operator()(VariableDeclaration& _varDecl)
+{
+	renameVariables(_varDecl.variables);
+	ASTModifier::operator()(_varDecl);
+}
+
+void VarNameCleaner::renameVariables(vector<TypedName>& _variables)
+{
+	for (TypedName& typedName: _variables)
+	{
+		auto newName = findCleanName(typedName.name);
+		if (newName != typedName.name)
+		{
+			m_translatedNames[typedName.name] = newName;
+			typedName.name = newName;
+		}
+		m_usedNames.insert(typedName.name);
+	}
+}
+
+void VarNameCleaner::operator()(Identifier& _identifier)
+{
+	auto name = m_translatedNames.find(_identifier.name);
+	if (name != m_translatedNames.end())
+		_identifier.name = name->second;
+}
+
+YulString VarNameCleaner::findCleanName(YulString const& _name) const
+{
+	auto newName = stripSuffix(_name);
+	if (newName != YulString{} && !isUsedName(newName))
+		return newName;
+
+	// create new name with suffix (by finding a free identifier)
+	for (size_t i = 1; i < numeric_limits<decltype(i)>::max(); ++i)
+	{
+		YulString newNameSuffixed = YulString{newName.str() + "_" + to_string(i)};
+		if (!isUsedName(newNameSuffixed))
+			return newNameSuffixed;
+	}
+	yulAssert(false, "Exhausted by attempting to find an available suffix.");
+}
+
+bool VarNameCleaner::isUsedName(YulString const& _name) const
+{
+	return m_dialect.builtin(_name) || m_usedNames.count(_name);
+}
+
+YulString VarNameCleaner::stripSuffix(YulString const& _name) const
+{
+	static regex const suffixRegex("(_+[0-9]+)+$");
+
+	smatch suffixMatch;
+	if (regex_search(_name.str(), suffixMatch, suffixRegex))
+		return {YulString{suffixMatch.prefix().str()}};
+	return _name;
+}