Add equivalent function combiner as Yul optimizer step.

libyul/optimiser/EquivalentFunctionDetector.cpp

@@ -0,0 +1,63 @@
+/*
+	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 combines syntactically equivalent functions.
+ */
+
+#include <libyul/optimiser/EquivalentFunctionDetector.h>
+#include <libyul/optimiser/SyntacticalEquality.h>
+
+#include <libyul/AsmData.h>
+#include <libyul/optimiser/Metrics.h>
+
+using namespace std;
+using namespace dev;
+using namespace yul;
+using namespace solidity;
+
+void EquivalentFunctionDetector::operator()(FunctionDefinition const& _fun)
+{
+	RoughHeuristic heuristic(_fun);
+	auto& candidates = m_candidates[heuristic];
+	for (auto const& candidate: candidates)
+		if (SyntacticallyEqual{}.statementEqual(_fun, *candidate))
+		{
+			m_duplicates[_fun.name] = candidate;
+			return;
+		}
+	candidates.push_back(&_fun);
+}
+
+bool EquivalentFunctionDetector::RoughHeuristic::operator<(EquivalentFunctionDetector::RoughHeuristic const& _rhs) const
+{
+	if (
+		std::make_tuple(m_fun.parameters.size(), m_fun.returnVariables.size()) ==
+		std::make_tuple(_rhs.m_fun.parameters.size(), _rhs.m_fun.returnVariables.size())
+	)
+		return codeSize() < _rhs.codeSize();
+	else
+		return
+			std::make_tuple(m_fun.parameters.size(), m_fun.returnVariables.size()) <
+			std::make_tuple(_rhs.m_fun.parameters.size(), _rhs.m_fun.returnVariables.size());
+}
+
+size_t EquivalentFunctionDetector::RoughHeuristic::codeSize() const
+{
+	if (!m_codeSize)
+		m_codeSize = CodeSize::codeSize(m_fun.body);
+	return *m_codeSize;
+}