Name simplifier.

libyul/optimiser/NameSimplifier.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/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;
+}

libyul/optimiser/NameSimplifier.h

@@ -0,0 +1,76 @@
+/*
+	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/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+
+#pragma once
+
+#include <libyul/AsmDataForward.h>
+#include <libyul/optimiser/ASTWalker.h>
+#include <libyul/YulString.h>
+#include <libyul/optimiser/OptimiserStep.h>
+
+#include <map>
+#include <set>
+#include <string>
+
+namespace solidity::yul
+{
+
+struct Dialect;
+
+/**
+ * Pass to "simplify" all identifier names.
+ *
+ * The purpose of this is to make generated code more readable, but also
+ * to remove AST identifiers that could lead to a different sorting order
+ * and thus influence e.g. the order of function inlining.
+ *
+ * Prerequisites: Disambiguator, FunctionHoister, FunctionGrouper
+ */
+class NameSimplifier: public ASTModifier
+{
+public:
+	static constexpr char const* name{"NameSimplifier"};
+	static void run(OptimiserStepContext& _context, Block& _ast)
+	{
+		NameSimplifier{_context, _ast}(_ast);
+	}
+
+	using ASTModifier::operator();
+	void operator()(VariableDeclaration& _varDecl) override;
+	void operator()(Identifier& _identifier) override;
+	void operator()(FunctionCall& _funCall) override;
+	void operator()(FunctionDefinition& _funDef) override;
+
+private:
+	NameSimplifier(
+		OptimiserStepContext& _context,
+		Block const& _ast
+	);
+
+	/// Tries to rename a list of variables.
+	void renameVariables(std::vector<TypedName>& _variables);
+
+	void findSimplification(YulString _name);
+	void translate(YulString& _name);
+
+	OptimiserStepContext& m_context;
+	std::set<YulString> m_usedNames;
+	std::map<YulString, YulString> m_translations;
+};
+
+}

libyul/optimiser/Suite.cpp

@@ -57,6 +57,7 @@
 #include <libyul/optimiser/LoadResolver.h>
 #include <libyul/optimiser/LoopInvariantCodeMotion.h>
 #include <libyul/optimiser/Metrics.h>
+#include <libyul/optimiser/NameSimplifier.h>
 #include <libyul/backends/evm/ConstantOptimiser.h>
 #include <libyul/AsmAnalysis.h>
 #include <libyul/AsmAnalysisInfo.h>
@@ -181,6 +182,7 @@ map<string, unique_ptr<OptimiserStep>> const& OptimiserSuite::allSteps()
 			LiteralRematerialiser,
 			LoadResolver,
 			LoopInvariantCodeMotion,
+			NameSimplifier,
 			RedundantAssignEliminator,
 			Rematerialiser,
 			SSAReverser,
@@ -218,6 +220,7 @@ map<string, char> const& OptimiserSuite::stepNameToAbbreviationMap()
 		{LiteralRematerialiser::name,         'T'},
 		{LoadResolver::name,                  'L'},
 		{LoopInvariantCodeMotion::name,       'M'},
+		{NameSimplifier::name,                'N'},
 		{RedundantAssignEliminator::name,     'r'},
 		{Rematerialiser::name,                'm'},
 		{SSAReverser::name,                   'V'},