Use index into m_asm->items() to modify free memory push.

libevmasm/AssemblyItem.h

@@ -62,9 +62,6 @@ public:
 
 	AssemblyItem(u256 _push, langutil::SourceLocation _location = langutil::SourceLocation()):
 		AssemblyItem(Push, std::move(_push), std::move(_location)) { }
-	/// Used only for the free memory pointer as "memoryguard". Should probably be replaced by a separate AssemblyItemType.
-	AssemblyItem(std::shared_ptr<u256> _pushData, langutil::SourceLocation _location = langutil::SourceLocation()):
-		m_type(Push), m_data(std::move(_pushData)), m_location(std::move(_location)) { }
 	AssemblyItem(Instruction _i, langutil::SourceLocation _location = langutil::SourceLocation()):
 		m_type(Operation),
 		m_instruction(_i),

libsolidity/codegen/CompilerContext.cpp

@@ -545,7 +545,13 @@ void CompilerContext::optimizeYul(
 
 	bool const isCreation = runtimeContext() != nullptr;
 	yul::GasMeter meter(_dialect, isCreation, _optimiserSettings.expectedExecutionsPerDeployment);
+	unique_ptr<u256> freeMemoryInitPushValue;
+	if (_system)
+	{
 		solAssert(m_freeMemoryInitPush, "");
+		solAssert(m_asm->items().size() > *m_freeMemoryInitPush, "");
+		freeMemoryInitPushValue = make_unique<u256>(m_asm->items().at(*m_freeMemoryInitPush).data());
+	}
 	yul::OptimiserSuite::run(
 		_dialect,
 		&meter,
@@ -554,8 +560,10 @@ void CompilerContext::optimizeYul(
 		_optimiserSettings.yulOptimiserSteps,
 		isCreation? nullopt : make_optional(_optimiserSettings.expectedExecutionsPerDeployment),
 		_externalIdentifiers,
-		_system ? m_freeMemoryInitPush : shared_ptr<u256>{}
+		freeMemoryInitPushValue.get()
 	);
+	if (_system)
+		m_asm->items().at(*m_freeMemoryInitPush).setData(*freeMemoryInitPushValue);
 
 #ifdef SOL_OUTPUT_ASM
 	cout << "After optimizer:" << endl;
@@ -572,6 +580,12 @@ string CompilerContext::revertReasonIfDebug(string const& _message)
 	);
 }
 
+void CompilerContext::appendFreeMemoryInitPush(u256 _value)
+{
+	m_freeMemoryInitPush = m_asm->items().size();
+	m_asm->append(AssemblyItem(_value));
+}
+
 void CompilerContext::updateSourceLocation()
 {
 	m_asm->setSourceLocation(m_visitedNodes.empty() ? SourceLocation() : m_visitedNodes.top()->location());

libsolidity/codegen/CompilerContext.h

@@ -315,11 +315,7 @@ public:
 
 	RevertStrings revertStrings() const { return m_revertStrings; }
 
-	evmasm::AssemblyItem makeFreeMemoryInitPush(u256 _value)
+	void appendFreeMemoryInitPush(u256 _value);
-	{
-		m_freeMemoryInitPush = std::make_shared<u256>(_value);
-		return evmasm::AssemblyItem(m_freeMemoryInitPush);
-	}
 
 private:
 	/// Updates source location set in the assembly.
@@ -406,8 +402,8 @@ private:
 	std::queue<std::tuple<std::string, unsigned, unsigned, std::function<void(CompilerContext&)>>> m_lowLevelFunctionGenerationQueue;
 	/// Flag to check that appendYulUtilityFunctions() was called exactly once
 	bool m_appendYulUtilityFunctionsRan = false;
-	/// The assembly item that pushes the initial value of the free memory pointer.
+	/// The index of the assembly item that pushes the initial value of the free memory pointer.
-	std::shared_ptr<u256> m_freeMemoryInitPush;
+	std::optional<size_t> m_freeMemoryInitPush;
 };
 
 }

libsolidity/codegen/CompilerUtils.cpp

@@ -55,7 +55,7 @@ void CompilerUtils::initialiseFreeMemoryPointer()
 {
 	size_t reservedMemory = m_context.reservedMemory();
 	solAssert(bigint(generalPurposeMemoryStart) + bigint(reservedMemory) < bigint(1) << 63, "");
-	m_context << m_context.makeFreeMemoryInitPush((u256(generalPurposeMemoryStart) + reservedMemory));
+	m_context.appendFreeMemoryInitPush((u256(generalPurposeMemoryStart) + reservedMemory));
 	storeFreeMemoryPointer();
 }
 

libyul/optimiser/OptimiserStep.h

@@ -41,7 +41,7 @@ struct OptimiserStepContext
 	std::set<YulString> const& reservedIdentifiers;
 	/// The value nullopt represents creation code
 	std::optional<size_t> expectedExecutionsPerDeployment;
-	std::shared_ptr<u256> externalFreeMemoryPointerInitializer{};
+	u256* externalFreeMemoryPointerInitializer = nullptr;
 };
 
 

libyul/optimiser/Suite.cpp

@@ -90,7 +90,7 @@ void OptimiserSuite::run(
 	string const& _optimisationSequence,
 	optional<size_t> _expectedExecutionsPerDeployment,
 	set<YulString> const& _externallyUsedIdentifiers,
-	std::shared_ptr<u256> _externalFreeMemoryPointerInitializer
+	u256* _externalFreeMemoryPointerInitializer
 )
 {
 	EVMDialect const* evmDialect = dynamic_cast<EVMDialect const*>(&_dialect);

libyul/optimiser/Suite.h

@@ -67,7 +67,7 @@ public:
 		std::string const& _optimisationSequence,
 		std::optional<size_t> _expectedExecutionsPerDeployment,
 		std::set<YulString> const& _externallyUsedIdentifiers = {},
-		std::shared_ptr<u256> _externalFreeMemoryPointerInitializer = {}
+		u256* _externalFreeMemoryPointerInitializer = nullptr
 	);
 
 	/// Ensures that specified sequence of step abbreviations is well-formed and can be executed.
@@ -93,7 +93,7 @@ private:
 		Debug _debug,
 		Block& _ast,
 		std::optional<size_t> expectedExecutionsPerDeployment,
-		std::shared_ptr<u256> _externalFreeMemoryPointerInitializer = {}
+		u256* _externalFreeMemoryPointerInitializer = nullptr
 
 	):
 		m_dispenser{_dialect, _ast, _externallyUsedIdentifiers},