Add equivalent function combiner as Yul optimizer step.

20 files changed, 759 insertions, 163 deletions

diff --git a/libdevcore/CommonData.h b/libdevcore/CommonData.h
index 7c59c505..1d668f26 100644
--- a/libdevcore/CommonData.h
+++ b/libdevcore/CommonData.h
@@ -275,4 +275,10 @@ std::string getChecksummedAddress(std::string const& _addr);
 bool isValidHex(std::string const& _string);
 bool isValidDecimal(std::string const& _string);
 
+template<typename Container, typename Compare>
+bool containerEqual(Container const& _lhs, Container const& _rhs, Compare&& _compare)
+{
+	return std::equal(std::begin(_lhs), std::end(_lhs), std::begin(_rhs), std::end(_rhs), std::forward<Compare>(_compare));
+}
+
 }
diff --git a/libyul/CMakeLists.txt b/libyul/CMakeLists.txt
index ad9812bd..44af2fc3 100644
--- a/libyul/CMakeLists.txt
+++ b/libyul/CMakeLists.txt
@@ -44,6 +44,10 @@ add_library(yul
 	optimiser/DataFlowAnalyzer.h
 	optimiser/Disambiguator.cpp
 	optimiser/Disambiguator.h
+	optimiser/EquivalentFunctionDetector.cpp
+	optimiser/EquivalentFunctionDetector.h
+	optimiser/EquivalentFunctionCombiner.cpp
+	optimiser/EquivalentFunctionCombiner.h
 	optimiser/ExpressionInliner.cpp
 	optimiser/ExpressionInliner.h
 	optimiser/ExpressionJoiner.cpp
diff --git a/libyul/optimiser/CommonSubexpressionEliminator.cpp b/libyul/optimiser/CommonSubexpressionEliminator.cpp
index 8ce003e7..5f182eba 100644
--- a/libyul/optimiser/CommonSubexpressionEliminator.cpp
+++ b/libyul/optimiser/CommonSubexpressionEliminator.cpp
@@ -74,7 +74,7 @@ void CommonSubexpressionEliminator::visit(Expression& _e)
 		{
 			assertThrow(var.second, OptimizerException, "");
 			assertThrow(inScope(var.first), OptimizerException, "");
-			if (SyntacticalEqualityChecker::equal(_e, *var.second))
+			if (SyntacticallyEqual{}(_e, *var.second))
 			{
 				_e = Identifier{locationOf(_e), var.first};
 				break;
diff --git a/libyul/optimiser/EquivalentFunctionCombiner.cpp b/libyul/optimiser/EquivalentFunctionCombiner.cpp
new file mode 100644
index 00000000..939e63d2
--- /dev/null
+++ b/libyul/optimiser/EquivalentFunctionCombiner.cpp
@@ -0,0 +1,41 @@
+/*
+	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/EquivalentFunctionCombiner.h>
+#include <libyul/AsmData.h>
+#include <libdevcore/CommonData.h>
+
+using namespace std;
+using namespace dev;
+using namespace yul;
+using namespace dev::solidity;
+
+void EquivalentFunctionCombiner::run(Block& _ast)
+{
+	EquivalentFunctionCombiner{EquivalentFunctionDetector::run(_ast)}(_ast);
+}
+
+void EquivalentFunctionCombiner::operator()(FunctionCall& _funCall)
+{
+	auto it = m_duplicates.find(_funCall.functionName.name);
+	if (it != m_duplicates.end())
+		_funCall.functionName.name = it->second->name;
+	ASTModifier::operator()(_funCall);
+}
diff --git a/libyul/optimiser/EquivalentFunctionCombiner.h b/libyul/optimiser/EquivalentFunctionCombiner.h
new file mode 100644
index 00000000..0c766ded
--- /dev/null
+++ b/libyul/optimiser/EquivalentFunctionCombiner.h
@@ -0,0 +1,49 @@
+/*
+	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.
+ */
+#pragma once
+
+#include <libyul/optimiser/ASTWalker.h>
+#include <libyul/optimiser/EquivalentFunctionDetector.h>
+#include <libyul/AsmDataForward.h>
+
+namespace yul
+{
+
+/**
+ * Optimiser component that detects syntactically equivalent functions and replaces all calls to any of them by calls
+ * to one particular of them.
+ *
+ * Prerequisite: Disambiguator, Function Hoister
+ */
+class EquivalentFunctionCombiner: public ASTModifier
+{
+public:
+	static void run(Block& _ast);
+
+	using ASTModifier::operator();
+	void operator()(FunctionCall& _funCall) override;
+
+private:
+	EquivalentFunctionCombiner(std::map<YulString, FunctionDefinition const*> _duplicates): m_duplicates(std::move(_duplicates)) {}
+	std::map<YulString, FunctionDefinition const*> m_duplicates;
+};
+
+
+}
diff --git a/libyul/optimiser/EquivalentFunctionDetector.cpp b/libyul/optimiser/EquivalentFunctionDetector.cpp
new file mode 100644
index 00000000..d3a697bd
--- /dev/null
+++ b/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;
+}
diff --git a/libyul/optimiser/EquivalentFunctionDetector.h b/libyul/optimiser/EquivalentFunctionDetector.h
new file mode 100644
index 00000000..329fd385
--- /dev/null
+++ b/libyul/optimiser/EquivalentFunctionDetector.h
@@ -0,0 +1,71 @@
+/*
+	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.
+ */
+#pragma once
+
+#include <libyul/optimiser/ASTWalker.h>
+#include <libyul/AsmDataForward.h>
+
+namespace yul
+{
+
+/**
+ * Optimiser component that detects syntactically equivalent functions.
+ *
+ * Prerequisite: Disambiguator
+ */
+class EquivalentFunctionDetector: public ASTWalker
+{
+public:
+	static std::map<YulString, FunctionDefinition const*> run(Block& _block)
+	{
+		EquivalentFunctionDetector detector{};
+		detector(_block);
+		return std::move(detector.m_duplicates);
+	}
+
+	using ASTWalker::operator();
+	void operator()(FunctionDefinition const& _fun) override;
+
+private:
+	EquivalentFunctionDetector() = default;
+	/**
+	 * Fast heuristic to detect distinct, resp. potentially equal functions.
+	 *
+	 * Defines a partial order on function definitions. If two functions
+	 * are comparable (one is "less" than the other), they are distinct.
+	 * If not (neither is "less" than the other), they are *potentially* equal.
+	 */
+	class RoughHeuristic
+	{
+	public:
+		RoughHeuristic(FunctionDefinition const& _fun): m_fun(_fun) {}
+		bool operator<(RoughHeuristic const& _rhs) const;
+	private:
+		std::size_t codeSize() const;
+		FunctionDefinition const& m_fun;
+		mutable boost::optional<std::size_t> m_codeSize;
+		// In case the heuristic doesn't turn out to be good enough, we might want to define a hash function for code blocks.
+	};
+	std::map<RoughHeuristic, std::vector<FunctionDefinition const*>> m_candidates;
+	std::map<YulString, FunctionDefinition const*> m_duplicates;
+};
+
+
+}
diff --git a/libyul/optimiser/SimplificationRules.cpp b/libyul/optimiser/SimplificationRules.cpp
index 037dad97..1b620b64 100644
--- a/libyul/optimiser/SimplificationRules.cpp
+++ b/libyul/optimiser/SimplificationRules.cpp
@@ -171,7 +171,7 @@ bool Pattern::matches(
 			Expression const* firstMatch = (*m_matchGroups)[m_matchGroup];
 			assertThrow(firstMatch, OptimizerException, "Match set but to null.");
 			return
-				SyntacticalEqualityChecker::equal(*firstMatch, _expr) &&
+				SyntacticallyEqual{}(*firstMatch, _expr) &&
 				MovableChecker(_dialect, _expr).movable();
 		}
 		else if (m_kind == PatternKind::Any)
diff --git a/libyul/optimiser/Suite.cpp b/libyul/optimiser/Suite.cpp
index 48914cf8..38c0bf49 100644
--- a/libyul/optimiser/Suite.cpp
+++ b/libyul/optimiser/Suite.cpp
@@ -25,6 +25,7 @@
 #include <libyul/optimiser/BlockFlattener.h>
 #include <libyul/optimiser/FunctionGrouper.h>
 #include <libyul/optimiser/FunctionHoister.h>
+#include <libyul/optimiser/EquivalentFunctionCombiner.h>
 #include <libyul/optimiser/ExpressionSplitter.h>
 #include <libyul/optimiser/ExpressionJoiner.h>
 #include <libyul/optimiser/ExpressionInliner.h>
@@ -62,6 +63,8 @@ void OptimiserSuite::run(
 	(FunctionHoister{})(ast);
 	(BlockFlattener{})(ast);
 	(FunctionGrouper{})(ast);
+	EquivalentFunctionCombiner::run(ast);
+	UnusedPruner::runUntilStabilised(_dialect, ast, reservedIdentifiers);
 	(ForLoopInitRewriter{})(ast);
 	(BlockFlattener{})(ast);
 	StructuralSimplifier{_dialect}(ast);
@@ -101,6 +104,7 @@ void OptimiserSuite::run(
 		CommonSubexpressionEliminator{_dialect}(ast);
 
 		(FunctionGrouper{})(ast);
+		EquivalentFunctionCombiner::run(ast);
 		FullInliner{ast, dispenser}.run();
 
 		SSATransform::run(ast, dispenser);
diff --git a/libyul/optimiser/SyntacticalEquality.cpp b/libyul/optimiser/SyntacticalEquality.cpp
index 99ce06e5..ba8cc793 100644
--- a/libyul/optimiser/SyntacticalEquality.cpp
+++ b/libyul/optimiser/SyntacticalEquality.cpp
@@ -22,6 +22,7 @@
 
 #include <libyul/Exceptions.h>
 #include <libyul/AsmData.h>
+#include <libyul/Utilities.h>
 
 #include <libdevcore/CommonData.h>
 
@@ -29,48 +30,166 @@ using namespace std;
 using namespace dev;
 using namespace yul;
 
-bool SyntacticalEqualityChecker::equal(Expression const& _e1, Expression const& _e2)
+bool SyntacticallyEqual::operator()(Expression const& _lhs, Expression const& _rhs)
 {
-	if (_e1.type() != _e2.type())
+	return boost::apply_visitor([this](auto&& _lhsExpr, auto&& _rhsExpr) -> bool {
+		// ``this->`` is redundant, but required to work around a bug present in gcc 6.x.
+		return this->expressionEqual(_lhsExpr, _rhsExpr);
+	}, _lhs, _rhs);
+}
+
+bool SyntacticallyEqual::operator()(Statement const& _lhs, Statement const& _rhs)
+{
+	return boost::apply_visitor([this](auto&& _lhsStmt, auto&& _rhsStmt) -> bool {
+		// ``this->`` is redundant, but required to work around a bug present in gcc 6.x.
+		return this->statementEqual(_lhsStmt, _rhsStmt);
+	}, _lhs, _rhs);
+}
+
+bool SyntacticallyEqual::expressionEqual(FunctionalInstruction const& _lhs, FunctionalInstruction const& _rhs)
+{
+	return
+		_lhs.instruction == _rhs.instruction &&
+		containerEqual(_lhs.arguments, _rhs.arguments, [this](Expression const& _lhsExpr, Expression const& _rhsExpr) -> bool {
+			return (*this)(_lhsExpr, _rhsExpr);
+		});
+}
+
+bool SyntacticallyEqual::expressionEqual(FunctionCall const& _lhs, FunctionCall const& _rhs)
+{
+	return
+		expressionEqual(_lhs.functionName, _rhs.functionName) &&
+		containerEqual(_lhs.arguments, _rhs.arguments, [this](Expression const& _lhsExpr, Expression const& _rhsExpr) -> bool {
+			return (*this)(_lhsExpr, _rhsExpr);
+		});
+}
+
+bool SyntacticallyEqual::expressionEqual(Identifier const& _lhs, Identifier const& _rhs)
+{
+	auto lhsIt = m_identifiersLHS.find(_lhs.name);
+	auto rhsIt = m_identifiersRHS.find(_rhs.name);
+	return
+		(lhsIt == m_identifiersLHS.end() && rhsIt == m_identifiersRHS.end() && _lhs.name == _rhs.name) ||
+		(lhsIt != m_identifiersLHS.end() && rhsIt != m_identifiersRHS.end() && lhsIt->second == rhsIt->second);
+}
+bool SyntacticallyEqual::expressionEqual(Literal const& _lhs, Literal const& _rhs)
+{
+	if (_lhs.kind != _rhs.kind || _lhs.type != _rhs.type)
 		return false;
-	// TODO This somehow calls strcmp - WHERE?
-
-	// TODO This should be replaced by some kind of AST walker as soon as it gets
-	// more complex.
-	if (_e1.type() == typeid(FunctionalInstruction))
-	{
-		auto const& e1 = boost::get<FunctionalInstruction>(_e1);
-		auto const& e2 = boost::get<FunctionalInstruction>(_e2);
-		return
-			e1.instruction == e2.instruction &&
-			equalVector(e1.arguments, e2.arguments);
-	}
-	else if (_e1.type() == typeid(FunctionCall))
-	{
-		auto const& e1 = boost::get<FunctionCall>(_e1);
-		auto const& e2 = boost::get<FunctionCall>(_e2);
-		return
-			equal(e1.functionName, e2.functionName) &&
-			equalVector(e1.arguments, e2.arguments);
-	}
-	else if (_e1.type() == typeid(Identifier))
-		return boost::get<Identifier>(_e1).name == boost::get<Identifier>(_e2).name;
-	else if (_e1.type() == typeid(Literal))
-	{
-		auto const& e1 = boost::get<Literal>(_e1);
-		auto const& e2 = boost::get<Literal>(_e2);
-		return e1.kind == e2.kind && e1.value == e2.value && e1.type == e2.type;
-	}
+	if (_lhs.kind == LiteralKind::Number)
+		return valueOfNumberLiteral(_lhs) == valueOfNumberLiteral(_rhs);
 	else
-	{
-		assertThrow(false, OptimizerException, "Invalid expression");
-	}
-	return false;
+		return _lhs.value == _rhs.value;
 }
 
-bool SyntacticalEqualityChecker::equalVector(vector<Expression> const& _e1, vector<Expression> const& _e2)
+bool SyntacticallyEqual::statementEqual(ExpressionStatement const& _lhs, ExpressionStatement const& _rhs)
 {
-	return _e1.size() == _e2.size() &&
-		std::equal(begin(_e1), end(_e1), begin(_e2), SyntacticalEqualityChecker::equal);
+	return (*this)(_lhs.expression, _rhs.expression);
+}
+bool SyntacticallyEqual::statementEqual(Assignment const& _lhs, Assignment const& _rhs)
+{
+	return containerEqual(
+		_lhs.variableNames,
+		_rhs.variableNames,
+		[this](Identifier const& _lhsVarName, Identifier const& _rhsVarName) -> bool {
+			return this->expressionEqual(_lhsVarName, _rhsVarName);
+		}
+	) && (*this)(*_lhs.value, *_rhs.value);
+}
+
+bool SyntacticallyEqual::statementEqual(VariableDeclaration const& _lhs, VariableDeclaration const& _rhs)
+{
+	// first visit expression, then variable declarations
+	if (!compareSharedPtr<Expression, &SyntacticallyEqual::operator()>(_lhs.value, _rhs.value))
+		return false;
+	return containerEqual(_lhs.variables, _rhs.variables, [this](TypedName const& _lhsVarName, TypedName const& _rhsVarName) -> bool {
+		return this->visitDeclaration(_lhsVarName, _rhsVarName);
+	});
+}
 
+bool SyntacticallyEqual::statementEqual(FunctionDefinition const& _lhs, FunctionDefinition const& _rhs)
+{
+	auto compare = [this](TypedName const& _lhsVarName, TypedName const& _rhsVarName) -> bool {
+		return this->visitDeclaration(_lhsVarName, _rhsVarName);
+	};
+	// first visit parameter declarations, then body
+	if (!containerEqual(_lhs.parameters, _rhs.parameters, compare))
+		return false;
+	if (!containerEqual(_lhs.returnVariables, _rhs.returnVariables, compare))
+		return false;
+	return statementEqual(_lhs.body, _rhs.body);
+}
+
+bool SyntacticallyEqual::statementEqual(If const& _lhs, If const& _rhs)
+{
+	return
+		compareSharedPtr<Expression, &SyntacticallyEqual::operator()>(_lhs.condition, _rhs.condition) &&
+		statementEqual(_lhs.body, _rhs.body);
+}
+
+bool SyntacticallyEqual::statementEqual(Switch const& _lhs, Switch const& _rhs)
+{
+	static auto const sortCasesByValue = [](Case const* _lhsCase, Case const* _rhsCase) -> bool {
+		return Less<Literal*>{}(_lhsCase->value.get(), _rhsCase->value.get());
+	};
+	std::set<Case const*, decltype(sortCasesByValue)> lhsCases(sortCasesByValue);
+	std::set<Case const*, decltype(sortCasesByValue)> rhsCases(sortCasesByValue);
+	for (auto const& lhsCase: _lhs.cases)
+		lhsCases.insert(&lhsCase);
+	for (auto const& rhsCase: _rhs.cases)
+		rhsCases.insert(&rhsCase);
+	return
+		compareSharedPtr<Expression, &SyntacticallyEqual::operator()>(_lhs.expression, _rhs.expression) &&
+		containerEqual(lhsCases, rhsCases, [this](Case const* _lhsCase, Case const* _rhsCase) -> bool {
+			return this->switchCaseEqual(*_lhsCase, *_rhsCase);
+		});
+}
+
+
+bool SyntacticallyEqual::switchCaseEqual(Case const& _lhs, Case const& _rhs)
+{
+	return
+		compareSharedPtr<Literal, &SyntacticallyEqual::expressionEqual>(_lhs.value, _rhs.value) &&
+		statementEqual(_lhs.body, _rhs.body);
+}
+
+bool SyntacticallyEqual::statementEqual(ForLoop const& _lhs, ForLoop const& _rhs)
+{
+	return
+		statementEqual(_lhs.pre, _rhs.pre) &&
+		compareSharedPtr<Expression, &SyntacticallyEqual::operator()>(_lhs.condition, _rhs.condition) &&
+		statementEqual(_lhs.body, _rhs.body) &&
+		statementEqual(_lhs.post, _rhs.post);
+}
+
+bool SyntacticallyEqual::statementEqual(Instruction const&, Instruction const&)
+{
+	assertThrow(false, OptimizerException, "");
+}
+
+bool SyntacticallyEqual::statementEqual(Label const&, Label const&)
+{
+	assertThrow(false, OptimizerException, "");
+}
+
+bool SyntacticallyEqual::statementEqual(StackAssignment const&, StackAssignment const&)
+{
+	assertThrow(false, OptimizerException, "");
+}
+
+bool SyntacticallyEqual::statementEqual(Block const& _lhs, Block const& _rhs)
+{
+	return containerEqual(_lhs.statements, _rhs.statements, [this](Statement const& _lhsStmt, Statement const& _rhsStmt) -> bool {
+		return (*this)(_lhsStmt, _rhsStmt);
+	});
+}
+
+bool SyntacticallyEqual::visitDeclaration(TypedName const& _lhs, TypedName const& _rhs)
+{
+	if (_lhs.type != _rhs.type)
+		return false;
+	std::size_t id = m_idsUsed++;
+	m_identifiersLHS[_lhs.name] = id;
+	m_identifiersRHS[_rhs.name] = id;
+	return true;
 }
diff --git a/libyul/optimiser/SyntacticalEquality.h b/libyul/optimiser/SyntacticalEquality.h
index 63c51b4f..d4630d95 100644
--- a/libyul/optimiser/SyntacticalEquality.h
+++ b/libyul/optimiser/SyntacticalEquality.h
@@ -21,27 +21,69 @@
 #pragma once
 
 #include <libyul/AsmDataForward.h>
+#include <libyul/YulString.h>
 
-#include <vector>
+#include <map>
+#include <type_traits>
 
 namespace yul
 {
 
+
 /**
  * Component that can compare ASTs for equality on a syntactic basis.
- * Ignores source locations but requires exact matches otherwise.
+ * Ignores source locations and allows for different variable names but requires exact matches otherwise.
  *
- * TODO: Only implemented for Expressions for now.
- * A future version might also recognize renamed variables and thus could be used to
- * remove duplicate functions.
+ * Prerequisite: Disambiguator (unless only expressions are compared)
  */
-class SyntacticalEqualityChecker
+class SyntacticallyEqual
 {
 public:
-	static bool equal(Expression const& _e1, Expression const& _e2);
+	bool operator()(Expression const& _lhs, Expression const& _rhs);
+	bool operator()(Statement const& _lhs, Statement const& _rhs);
+
+	bool expressionEqual(FunctionalInstruction const& _lhs, FunctionalInstruction const& _rhs);
+	bool expressionEqual(FunctionCall const& _lhs, FunctionCall const& _rhs);
+	bool expressionEqual(Identifier const& _lhs, Identifier const& _rhs);
+	bool expressionEqual(Literal const& _lhs, Literal const& _rhs);
+
+	bool statementEqual(ExpressionStatement const& _lhs, ExpressionStatement const& _rhs);
+	bool statementEqual(Assignment const& _lhs, Assignment const& _rhs);
+	bool statementEqual(VariableDeclaration const& _lhs, VariableDeclaration const& _rhs);
+	bool statementEqual(FunctionDefinition const& _lhs, FunctionDefinition const& _rhs);
+	bool statementEqual(If const& _lhs, If const& _rhs);
+	bool statementEqual(Switch const& _lhs, Switch const& _rhs);
+	bool switchCaseEqual(Case const& _lhs, Case const& _rhs);
+	bool statementEqual(ForLoop const& _lhs, ForLoop const& _rhs);
+	bool statementEqual(Block const& _lhs, Block const& _rhs);
+private:
+	bool statementEqual(Instruction const& _lhs, Instruction const& _rhs);
+	bool statementEqual(Label const& _lhs, Label const& _rhs);
+	bool statementEqual(StackAssignment const& _lhs, StackAssignment const& _rhs);
+
+	bool visitDeclaration(TypedName const& _lhs, TypedName const& _rhs);
+
+	template<typename U, typename V>
+	bool expressionEqual(U const&, V const&, std::enable_if_t<!std::is_same<U, V>::value>* = nullptr)
+	{
+		return false;
+	}
+
+	template<typename U, typename V>
+	bool statementEqual(U const&, V const&, std::enable_if_t<!std::is_same<U, V>::value>* = nullptr)
+	{
+		return false;
+	}
+
+	template<typename T, bool (SyntacticallyEqual::*CompareMember)(T const&, T const&)>
+	bool compareSharedPtr(std::shared_ptr<T> const& _lhs, std::shared_ptr<T> const& _rhs)
+	{
+		return (_lhs == _rhs) || (_lhs && _rhs && (this->*CompareMember)(*_lhs, *_rhs));
+	}
 
-protected:
-	static bool equalVector(std::vector<Expression> const& _e1, std::vector<Expression> const& _e2);
+	std::size_t m_idsUsed = 0;
+	std::map<YulString, std::size_t> m_identifiersLHS;
+	std::map<YulString, std::size_t> m_identifiersRHS;
 };
 
 }
diff --git a/test/libyul/YulOptimizerTest.cpp b/test/libyul/YulOptimizerTest.cpp
index 0e3203cb..59cde4fe 100644
--- a/test/libyul/YulOptimizerTest.cpp
+++ b/test/libyul/YulOptimizerTest.cpp
@@ -26,6 +26,7 @@
 #include <libyul/optimiser/Disambiguator.h>
 #include <libyul/optimiser/CommonSubexpressionEliminator.h>
 #include <libyul/optimiser/NameCollector.h>
+#include <libyul/optimiser/EquivalentFunctionCombiner.h>
 #include <libyul/optimiser/ExpressionSplitter.h>
 #include <libyul/optimiser/FunctionGrouper.h>
 #include <libyul/optimiser/FunctionHoister.h>
@@ -217,6 +218,11 @@ bool YulOptimizerTest::run(ostream& _stream, string const& _linePrefix, bool con
 		disambiguate();
 		StructuralSimplifier{*m_dialect}(*m_ast);
 	}
+	else if (m_optimizerStep == "equivalentFunctionCombiner")
+	{
+		disambiguate();
+		EquivalentFunctionCombiner::run(*m_ast);
+	}
 	else if (m_optimizerStep == "fullSuite")
 		OptimiserSuite::run(*m_dialect, *m_ast, *m_analysisInfo);
 	else
diff --git a/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/multiple_complex.yul b/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/multiple_complex.yul
new file mode 100644
index 00000000..380f9f03
--- /dev/null
+++ b/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/multiple_complex.yul
@@ -0,0 +1,114 @@
+{
+  pop(f(1,2,3))
+  pop(g(4,5,6))
+  pop(h(7,8,9))
+  function f(f1, f2, f3) -> rf
+  {
+    switch f1
+        case 0 {
+            if f2
+            {
+                rf := f3
+            }
+            if not(f2)
+            {
+                rf := f1
+            }
+        }
+        default {
+            rf := 3
+        }
+  }
+  function g(g1, g2, g3) -> rg
+  {
+    switch g1
+        case 0 {
+            if g2
+            {
+                rg := g3
+            }
+            if not(g2)
+            {
+                rg := g1
+            }
+        }
+        default {
+            rg := 3
+        }
+  }
+  function h(h1, h2, h3) -> rh
+  {
+    switch h1
+        case 1 {
+            if h2
+            {
+                rh := h3
+            }
+            if not(h2)
+            {
+                rh := h1
+            }
+        }
+        default {
+            rh := 3
+        }
+  }
+}
+// ----
+// equivalentFunctionCombiner
+// {
+//     pop(f(1, 2, 3))
+//     pop(f(4, 5, 6))
+//     pop(h(7, 8, 9))
+//     function f(f1, f2, f3) -> rf
+//     {
+//         switch f1
+//         case 0 {
+//             if f2
+//             {
+//                 rf := f3
+//             }
+//             if not(f2)
+//             {
+//                 rf := f1
+//             }
+//         }
+//         default {
+//             rf := 3
+//         }
+//     }
+//     function g(g1, g2, g3) -> rg
+//     {
+//         switch g1
+//         case 0 {
+//             if g2
+//             {
+//                 rg := g3
+//             }
+//             if not(g2)
+//             {
+//                 rg := g1
+//             }
+//         }
+//         default {
+//             rg := 3
+//         }
+//     }
+//     function h(h1, h2, h3) -> rh
+//     {
+//         switch h1
+//         case 1 {
+//             if h2
+//             {
+//                 rh := h3
+//             }
+//             if not(h2)
+//             {
+//                 rh := h1
+//             }
+//         }
+//         default {
+//             rh := 3
+//         }
+//     }
+// }
diff --git a/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/simple.yul b/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/simple.yul
new file mode 100644
index 00000000..2d5b3ef8
--- /dev/null
+++ b/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/simple.yul
@@ -0,0 +1,20 @@
+{
+  f()
+  g()
+  function f() { mstore(1, mload(0)) }
+  function g() { mstore(1, mload(0)) }
+}
+// ----
+// equivalentFunctionCombiner
+// {
+//     f()
+//     f()
+//     function f()
+//     {
+//         mstore(1, mload(0))
+//     }
+//     function g()
+//     {
+//         mstore(1, mload(0))
+//     }
+// }
diff --git a/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/simple_different_vars.yul b/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/simple_different_vars.yul
new file mode 100644
index 00000000..d38a3d2e
--- /dev/null
+++ b/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/simple_different_vars.yul
@@ -0,0 +1,22 @@
+{
+  pop(f())
+  pop(g())
+  function f() -> b { let a := mload(0) b := a }
+  function g() -> a { let b := mload(0) a := b }
+}
+// ----
+// equivalentFunctionCombiner
+// {
+//     pop(f())
+//     pop(f())
+//     function f() -> b
+//     {
+//         let a := mload(0)
+//         b := a
+//     }
+//     function g() -> a_1
+//     {
+//         let b_2 := mload(0)
+//         a_1 := b_2
+//     }
+// }
diff --git a/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/switch_case_order.yul b/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/switch_case_order.yul
new file mode 100644
index 00000000..4f3cad36
--- /dev/null
+++ b/test/libyul/yulOptimizerTests/equivalentFunctionCombiner/switch_case_order.yul
@@ -0,0 +1,32 @@
+{
+  f(0)
+  g(1)
+  function f(x) { switch x case 0 { mstore(0, 42) } case 1 { mstore(1, 42) } }
+  function g(x) { switch x case 1 { mstore(1, 42) } case 0 { mstore(0, 42) } }
+}
+// ----
+// equivalentFunctionCombiner
+// {
+//     f(0)
+//     f(1)
+//     function f(x)
+//     {
+//         switch x
+//         case 0 {
+//             mstore(0, 42)
+//         }
+//         case 1 {
+//             mstore(1, 42)
+//         }
+//     }
+//     function g(x_1)
+//     {
+//         switch x_1
+//         case 1 {
+//             mstore(1, 42)
+//         }
+//         case 0 {
+//             mstore(0, 42)
+//         }
+//     }
+// }
diff --git a/test/libyul/yulOptimizerTests/fullSuite/abi2.yul b/test/libyul/yulOptimizerTests/fullSuite/abi2.yul
index bb60b1fa..887399b6 100644
--- a/test/libyul/yulOptimizerTests/fullSuite/abi2.yul
+++ b/test/libyul/yulOptimizerTests/fullSuite/abi2.yul
@@ -1073,12 +1073,12 @@
 // fullSuite
 // {
 //     let _2 := mload(1)
-//     let _1042 := mload(0)
-//     if slt(sub(_2, _1042), 64)
+//     let _172 := mload(0)
+//     if slt(sub(_2, _172), 64)
 //     {
 //         revert(0, 0)
 //     }
-//     sstore(0, and(calldataload(_1042), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF))
+//     sstore(0, and(calldataload(_172), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF))
 //     let x0, x1, x2, x3, x4 := abi_decode_tuple_t_addresst_uint256t_bytes_calldata_ptrt_enum$_Operation_$1949(mload(7), mload(8))
 //     sstore(x1, x0)
 //     sstore(x3, x2)
@@ -1093,40 +1093,40 @@
 //         value0_57 := and(calldataload(add(headStart_55, value4)), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)
 //         value1_58 := calldataload(add(headStart_55, 32))
 //         let offset_62 := calldataload(add(headStart_55, 64))
-//         let _1090 := 0xffffffffffffffff
-//         if gt(offset_62, _1090)
+//         let _220 := 0xffffffffffffffff
+//         if gt(offset_62, _220)
 //         {
 //             revert(value4, value4)
 //         }
-//         let _1092 := add(headStart_55, offset_62)
-//         if iszero(slt(add(_1092, 0x1f), dataEnd_56))
+//         let _222 := add(headStart_55, offset_62)
+//         if iszero(slt(add(_222, 0x1f), dataEnd_56))
 //         {
 //             revert(value4, value4)
 //         }
-//         let abi_decode_length_15_689 := calldataload(_1092)
-//         if gt(abi_decode_length_15_689, _1090)
+//         let abi_decode_length_15_116 := calldataload(_222)
+//         if gt(abi_decode_length_15_116, _220)
 //         {
 //             revert(value4, value4)
 //         }
-//         if gt(add(add(_1092, abi_decode_length_15_689), 0x20), dataEnd_56)
+//         if gt(add(add(_222, abi_decode_length_15_116), 32), dataEnd_56)
 //         {
 //             revert(value4, value4)
 //         }
-//         value2_59 := add(_1092, 0x20)
-//         value3 := abi_decode_length_15_689
-//         let _1095 := calldataload(add(headStart_55, 96))
-//         if iszero(lt(_1095, 3))
+//         value2_59 := add(_222, 32)
+//         value3 := abi_decode_length_15_116
+//         let _225 := calldataload(add(headStart_55, 96))
+//         if iszero(lt(_225, 3))
 //         {
 //             revert(value4, value4)
 //         }
-//         value4 := _1095
+//         value4 := _225
 //     }
 //     function abi_encode_tuple_t_bytes32_t_address_t_uint256_t_bytes32_t_enum$_Operation_$1949_t_uint256_t_uint256_t_uint256_t_address_t_address_t_uint256__to_t_bytes32_t_address_t_uint256_t_bytes32_t_uint8_t_uint256_t_uint256_t_uint256_t_address_t_address_t_uint256_(headStart_252, value10_253, value9_254, value8_255, value7_256, value6_257, value5_258, value4_259, value3_260, value2_261, value1_262, value0_263) -> tail_264
 //     {
 //         tail_264 := add(headStart_252, 352)
 //         mstore(headStart_252, value0_263)
-//         let _1307 := 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
-//         mstore(add(headStart_252, 32), and(value1_262, _1307))
+//         let _439 := 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
+//         mstore(add(headStart_252, 32), and(value1_262, _439))
 //         mstore(add(headStart_252, 64), value2_261)
 //         mstore(add(headStart_252, 96), value3_260)
 //         if iszero(lt(value4_259, 3))
@@ -1137,8 +1137,8 @@
 //         mstore(add(headStart_252, 160), value5_258)
 //         mstore(add(headStart_252, 192), value6_257)
 //         mstore(add(headStart_252, 224), value7_256)
-//         mstore(add(headStart_252, 256), and(value8_255, _1307))
-//         mstore(add(headStart_252, 288), and(value9_254, _1307))
+//         mstore(add(headStart_252, 256), and(value8_255, _439))
+//         mstore(add(headStart_252, 288), and(value9_254, _439))
 //         mstore(add(headStart_252, 320), value10_253)
 //     }
 // }
diff --git a/test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul b/test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul
index c909d39e..a8cac6c6 100644
--- a/test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul
+++ b/test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul
@@ -458,13 +458,14 @@
 // ----
 // fullSuite
 // {
+//     let _1 := 0x20
 //     let _2 := 0
-//     let _485 := mload(_2)
-//     let abi_encode_pos := 0x20
-//     let abi_encode_length_68 := mload(_485)
-//     mstore(0x20, abi_encode_length_68)
+//     let _268 := mload(_2)
+//     let abi_encode_pos := _1
+//     let abi_encode_length_68 := mload(_268)
+//     mstore(_1, abi_encode_length_68)
 //     abi_encode_pos := 64
-//     let abi_encode_srcPtr := add(_485, 0x20)
+//     let abi_encode_srcPtr := add(_268, _1)
 //     let abi_encode_i_69 := _2
 //     for {
 //     }
@@ -473,31 +474,45 @@
 //         abi_encode_i_69 := add(abi_encode_i_69, 1)
 //     }
 //     {
-//         abi_encode_t_array$_t_contract$_C_$55_$3_memory_to_t_array$_t_address_$3_memory_ptr(mload(abi_encode_srcPtr), abi_encode_pos)
-//         abi_encode_srcPtr := add(abi_encode_srcPtr, 0x20)
+//         let _668 := mload(abi_encode_srcPtr)
+//         let abi_encode_pos_71_760 := abi_encode_pos
+//         let abi_encode_srcPtr_73_762 := _668
+//         let abi_encode_i_74_763 := _2
+//         for {
+//         }
+//         lt(abi_encode_i_74_763, 0x3)
+//         {
+//             abi_encode_i_74_763 := add(abi_encode_i_74_763, 1)
+//         }
+//         {
+//             mstore(abi_encode_pos_71_760, and(mload(abi_encode_srcPtr_73_762), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF))
+//             abi_encode_srcPtr_73_762 := add(abi_encode_srcPtr_73_762, _1)
+//             abi_encode_pos_71_760 := add(abi_encode_pos_71_760, _1)
+//         }
+//         abi_encode_srcPtr := add(abi_encode_srcPtr, _1)
 //         abi_encode_pos := add(abi_encode_pos, 0x60)
 //     }
-//     let _487 := mload(0x40)
-//     let _488 := mload(0x20)
-//     if slt(sub(_487, _488), 128)
+//     let _270 := mload(64)
+//     let _271 := mload(_1)
+//     if slt(sub(_270, _271), 128)
 //     {
 //         revert(_2, _2)
 //     }
-//     let abi_decode_offset_64 := calldataload(add(_488, 64))
-//     let abi_decode__165 := 0xffffffffffffffff
-//     if gt(abi_decode_offset_64, abi_decode__165)
+//     let abi_decode_offset_64 := calldataload(add(_271, 64))
+//     let abi_decode__74 := 0xffffffffffffffff
+//     if gt(abi_decode_offset_64, abi_decode__74)
 //     {
 //         revert(_2, _2)
 //     }
-//     let abi_decode_value2_587 := abi_decode_t_array$_t_uint256_$dyn_memory_ptr(add(_488, abi_decode_offset_64), _487)
-//     let abi_decode_offset_65 := calldataload(add(_488, 96))
-//     if gt(abi_decode_offset_65, abi_decode__165)
+//     let abi_decode_value2_367 := abi_decode_t_array$_t_uint256_$dyn_memory_ptr(add(_271, abi_decode_offset_64), _270)
+//     let abi_decode_offset_65 := calldataload(add(_271, 96))
+//     if gt(abi_decode_offset_65, abi_decode__74)
 //     {
 //         revert(_2, _2)
 //     }
-//     let abi_decode_value3_588 := abi_decode_t_array$_t_array$_t_uint256_$2_memory_$dyn_memory_ptr(add(_488, abi_decode_offset_65), _487)
-//     sstore(calldataload(_488), calldataload(add(_488, 32)))
-//     sstore(abi_decode_value2_587, abi_decode_value3_588)
+//     let abi_decode_value3_368 := abi_decode_t_array$_t_array$_t_uint256_$2_memory_$dyn_memory_ptr(add(_271, abi_decode_offset_65), _270)
+//     sstore(calldataload(_271), calldataload(add(_271, _1)))
+//     sstore(abi_decode_value2_367, abi_decode_value3_368)
 //     sstore(_2, abi_encode_pos)
 //     function abi_decode_t_array$_t_array$_t_uint256_$2_memory_$dyn_memory_ptr(offset_3, end_4) -> array_5
 //     {
@@ -506,23 +521,19 @@
 //             revert(0, 0)
 //         }
 //         let length_6 := calldataload(offset_3)
-//         if gt(length_6, 0xffffffffffffffff)
+//         let array_5_115 := allocateMemory(array_allocation_size_t_array$_t_address_$dyn_memory(length_6))
+//         array_5 := array_5_115
+//         let dst_7 := array_5_115
+//         mstore(array_5_115, length_6)
+//         let _16 := 0x20
+//         dst_7 := add(array_5_115, _16)
+//         let src_8 := add(offset_3, _16)
+//         if gt(add(add(offset_3, mul(length_6, 0x40)), _16), end_4)
 //         {
 //             revert(0, 0)
 //         }
-//         let array_allo__217 := 0x20
-//         let array_5_254 := allocateMemory(add(mul(length_6, array_allo__217), array_allo__217))
-//         array_5 := array_5_254
-//         let dst_7 := array_5_254
-//         mstore(array_5_254, length_6)
-//         dst_7 := add(array_5_254, array_allo__217)
-//         let src_8 := add(offset_3, array_allo__217)
-//         if gt(add(add(offset_3, mul(length_6, 0x40)), array_allo__217), end_4)
-//         {
-//             revert(0, 0)
-//         }
-//         let i_9_566 := 0
-//         let i_9 := i_9_566
+//         let i_9_346 := 0
+//         let i_9 := i_9_346
 //         for {
 //         }
 //         lt(i_9, length_6)
@@ -532,16 +543,17 @@
 //         {
 //             if iszero(slt(add(src_8, 0x1f), end_4))
 //             {
-//                 revert(i_9_566, i_9_566)
+//                 revert(i_9_346, i_9_346)
 //             }
-//             let abi_decode_array_13_263 := allocateMemory(array_allocation_size_t_array$_t_uint256_$2_memory(0x2))
-//             let abi_decode_dst_15 := abi_decode_array_13_263
+//             let abi_decode_array_13_124 := allocateMemory(array_allocation_size_t_array$_t_uint256_$2_memory(0x2))
+//             let abi_decode_dst_15 := abi_decode_array_13_124
 //             let abi_decode_src_16 := src_8
-//             if gt(add(src_8, 64), end_4)
+//             let abi_decode__289 := add(src_8, 0x40)
+//             if gt(abi_decode__289, end_4)
 //             {
-//                 revert(i_9_566, i_9_566)
+//                 revert(i_9_346, i_9_346)
 //             }
-//             let abi_decode_i_17 := i_9_566
+//             let abi_decode_i_17 := i_9_346
 //             for {
 //             }
 //             lt(abi_decode_i_17, 0x2)
@@ -550,12 +562,12 @@
 //             }
 //             {
 //                 mstore(abi_decode_dst_15, calldataload(abi_decode_src_16))
-//                 abi_decode_dst_15 := add(abi_decode_dst_15, array_allo__217)
-//                 abi_decode_src_16 := add(abi_decode_src_16, array_allo__217)
+//                 abi_decode_dst_15 := add(abi_decode_dst_15, _16)
+//                 abi_decode_src_16 := add(abi_decode_src_16, _16)
 //             }
-//             mstore(dst_7, abi_decode_array_13_263)
-//             dst_7 := add(dst_7, array_allo__217)
-//             src_8 := add(src_8, 0x40)
+//             mstore(dst_7, abi_decode_array_13_124)
+//             dst_7 := add(dst_7, _16)
+//             src_8 := abi_decode__289
 //         }
 //     }
 //     function abi_decode_t_array$_t_uint256_$dyn_memory_ptr(offset_27, end_28) -> array_29
@@ -565,19 +577,14 @@
 //             revert(0, 0)
 //         }
 //         let length_30 := calldataload(offset_27)
-//         if gt(length_30, 0xffffffffffffffff)
-//         {
-//             revert(0, 0)
-//         }
-//         let array_allo__234 := 0x20
-//         let array_allo__560 := mul(length_30, array_allo__234)
-//         let array_29_279 := allocateMemory(add(array_allo__560, array_allo__234))
-//         array_29 := array_29_279
-//         let dst_31 := array_29_279
-//         mstore(array_29_279, length_30)
-//         dst_31 := add(array_29_279, array_allo__234)
-//         let src_32 := add(offset_27, array_allo__234)
-//         if gt(add(add(offset_27, array_allo__560), array_allo__234), end_28)
+//         let array_29_131 := allocateMemory(array_allocation_size_t_array$_t_address_$dyn_memory(length_30))
+//         array_29 := array_29_131
+//         let dst_31 := array_29_131
+//         mstore(array_29_131, length_30)
+//         let _52 := 0x20
+//         dst_31 := add(array_29_131, _52)
+//         let src_32 := add(offset_27, _52)
+//         if gt(add(add(offset_27, mul(length_30, _52)), _52), end_28)
 //         {
 //             revert(0, 0)
 //         }
@@ -590,36 +597,28 @@
 //         }
 //         {
 //             mstore(dst_31, calldataload(src_32))
-//             dst_31 := add(dst_31, array_allo__234)
-//             src_32 := add(src_32, array_allo__234)
+//             dst_31 := add(dst_31, _52)
+//             src_32 := add(src_32, _52)
 //         }
 //     }
-//     function abi_encode_t_array$_t_contract$_C_$55_$3_memory_to_t_array$_t_address_$3_memory_ptr(value_70, pos_71)
+//     function allocateMemory(size) -> memPtr
 //     {
-//         let srcPtr_73 := value_70
-//         let i_74 := 0
-//         for {
-//         }
-//         lt(i_74, 0x3)
-//         {
-//             i_74 := add(i_74, 1)
-//         }
+//         let memPtr_157 := mload(64)
+//         memPtr := memPtr_157
+//         let newFreePtr := add(memPtr_157, size)
+//         if or(gt(newFreePtr, 0xffffffffffffffff), lt(newFreePtr, memPtr_157))
 //         {
-//             mstore(pos_71, and(mload(srcPtr_73), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF))
-//             srcPtr_73 := add(srcPtr_73, 0x20)
-//             pos_71 := add(pos_71, 0x20)
+//             revert(0, 0)
 //         }
+//         mstore(64, newFreePtr)
 //     }
-//     function allocateMemory(size) -> memPtr
+//     function array_allocation_size_t_array$_t_address_$dyn_memory(length_90) -> size_91
 //     {
-//         let memPtr_315 := mload(64)
-//         memPtr := memPtr_315
-//         let newFreePtr := add(memPtr_315, size)
-//         if or(gt(newFreePtr, 0xffffffffffffffff), lt(newFreePtr, memPtr_315))
+//         if gt(length_90, 0xffffffffffffffff)
 //         {
 //             revert(0, 0)
 //         }
-//         mstore(64, newFreePtr)
+//         size_91 := add(mul(length_90, 0x20), 0x20)
 //     }
 //     function array_allocation_size_t_array$_t_uint256_$2_memory(length_94) -> size_95
 //     {
diff --git a/test/libyul/yulOptimizerTests/fullSuite/aztec.yul b/test/libyul/yulOptimizerTests/fullSuite/aztec.yul
index 4fcdaaf1..fc09b5d9 100644
--- a/test/libyul/yulOptimizerTests/fullSuite/aztec.yul
+++ b/test/libyul/yulOptimizerTests/fullSuite/aztec.yul
@@ -264,10 +264,10 @@
 //     }
 //     {
 //         let validateJo__34 := 0x20
-//         let validateJo__376 := add(validateJo__10, mul(validateJo_i, 0xc0))
-//         let validateJo_noteIndex := add(validateJo__376, 36)
+//         let validateJo__373 := add(validateJo__10, mul(validateJo_i, 0xc0))
+//         let validateJo_noteIndex := add(validateJo__373, 0x24)
 //         let validateJo_k := validateJo_i_290
-//         let validateJo_a_292 := calldataload(add(validateJo__376, 68))
+//         let validateJo_a_292 := calldataload(add(validateJo__373, 0x44))
 //         let validateJo_a := validateJo_a_292
 //         let validateJo_c := validateJo_challenge
 //         let validateJo__39 := add(validateJo_i, 0x01)
@@ -286,18 +286,18 @@
 //         switch gt(validateJo__39, validateJo_m)
 //         case 1 {
 //             validateJo_kn := addmod(validateJo_kn, sub(validateJo_gen_order, validateJo_k), validateJo_gen_order)
-//             let validateJo_x := mod(mload(0x00), validateJo_gen_order)
+//             let validateJo_x := mod(mload(validateJo_i_290), validateJo_gen_order)
 //             validateJo_k := mulmod(validateJo_k, validateJo_x, validateJo_gen_order)
 //             validateJo_a := mulmod(validateJo_a_292, validateJo_x, validateJo_gen_order)
 //             validateJo_c := mulmod(validateJo_challenge, validateJo_x, validateJo_gen_order)
-//             mstore(0x00, keccak256(0x00, validateJo__34))
+//             mstore(validateJo_i_290, keccak256(validateJo_i_290, validateJo__34))
 //         }
 //         case 0 {
 //             validateJo_kn := addmod(validateJo_kn, validateJo_k, validateJo_gen_order)
 //         }
 //         let validateJo__52 := 0x40
-//         calldatacopy(0xe0, add(validateJo__376, 164), validateJo__52)
-//         calldatacopy(validateJo__34, add(validateJo__376, 100), validateJo__52)
+//         calldatacopy(0xe0, add(validateJo__373, 164), validateJo__52)
+//         calldatacopy(validateJo__34, add(validateJo__373, 100), validateJo__52)
 //         let validateJo__61 := 0x120
 //         mstore(validateJo__61, sub(validateJo_gen_order, validateJo_c))
 //         let validateJo__62 := 0x60
@@ -329,8 +329,8 @@
 //         }
 //         if iszero(validateJo_result)
 //         {
-//             mstore(0x00, 400)
-//             revert(0x00, validateJo__34)
+//             mstore(validateJo_i_290, 400)
+//             revert(validateJo_i_290, validateJo__34)
 //         }
 //         validateJo_b := add(validateJo_b, validateJo__52)
 //     }
@@ -340,13 +340,13 @@
 //     }
 //     if iszero(eq(mod(keccak256(validateJo__24, add(validateJo_b, 0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffd60)), validateJo_gen_order), validateJo_challenge))
 //     {
-//         mstore(0x00, 404)
-//         revert(0x00, 0x20)
+//         mstore(validateJo_i_290, 404)
+//         revert(validateJo_i_290, 0x20)
 //     }
-//     mstore(0x00, 0x01)
-//     return(0x00, 0x20)
-//     mstore(0x00, 404)
-//     revert(0x00, 0x20)
+//     mstore(validateJo_i_290, 0x01)
+//     return(validateJo_i_290, 0x20)
+//     mstore(validateJo_i_290, 404)
+//     revert(validateJo_i_290, 0x20)
 //     function validatePairing(t2)
 //     {
 //         let t2_x_1 := calldataload(t2)
@@ -379,8 +379,8 @@
 //         let success := call(gas(), 8, 0, _165, _216, _165, _165)
 //         if or(iszero(success), iszero(mload(_165)))
 //         {
-//             mstore(0x00, 400)
-//             revert(0x00, _165)
+//             mstore(0, 400)
+//             revert(0, _165)
 //         }
 //     }
 //     function validateCommitment(note, k_1, a_2)
@@ -409,6 +409,6 @@
 //         {
 //             calldatacopy(add(0x300, mul(i_7, 0x80)), add(add(notes_5, mul(i_7, 0xc0)), 0x60), 0x80)
 //         }
-//         mstore(0x00, keccak256(0x300, mul(n_6, 0x80)))
+//         mstore(0, keccak256(0x300, mul(n_6, 0x80)))
 //     }
 // }
diff --git a/test/tools/yulopti.cpp b/test/tools/yulopti.cpp
index ac21fd91..efd1ba05 100644
--- a/test/tools/yulopti.cpp
+++ b/test/tools/yulopti.cpp
@@ -33,6 +33,7 @@
 #include <libyul/optimiser/Disambiguator.h>
 #include <libyul/optimiser/CommonSubexpressionEliminator.h>
 #include <libyul/optimiser/NameCollector.h>
+#include <libyul/optimiser/EquivalentFunctionCombiner.h>
 #include <libyul/optimiser/ExpressionSplitter.h>
 #include <libyul/optimiser/FunctionGrouper.h>
 #include <libyul/optimiser/FunctionHoister.h>
@@ -128,7 +129,7 @@ public:
 			cout << "(q)quit/(f)flatten/(c)se/initialize var(d)ecls/(x)plit/(j)oin/(g)rouper/(h)oister/" << endl;
 			cout << "  (e)xpr inline/(i)nline/(s)implify/(u)nusedprune/ss(a) transform/" << endl;
 			cout << "  (r)edundant assign elim./re(m)aterializer/f(o)r-loop-pre-rewriter/" << endl;
-			cout << "  s(t)ructural simplifier? " << endl;
+			cout << "  s(t)ructural simplifier/equi(v)alent function combiner? " << endl;
 			cout.flush();
 			int option = readStandardInputChar();
 			cout << ' ' << char(option) << endl;
@@ -184,6 +185,9 @@ public:
 			case 'm':
 				Rematerialiser::run(*m_dialect, *m_ast);
 				break;
+			case 'v':
+				EquivalentFunctionCombiner::run(*m_ast);
+				break;
 			default:
 				cout << "Unknown option." << endl;
 			}