Allow stack limit evasion in system yul routines during old code generation.

libsolidity/codegen/CompilerContext.cpp

@@ -484,7 +484,7 @@ void CompilerContext::appendInlineAssembly(
 		obj.code = parserResult;
 		obj.analysisInfo = make_shared<yul::AsmAnalysisInfo>(analysisInfo);
 
-		optimizeYul(obj, dialect, _optimiserSettings, externallyUsedIdentifiers);
+		optimizeYul(obj, dialect, _optimiserSettings, externallyUsedIdentifiers, _system);
 
 		if (_system)
 		{
@@ -531,7 +531,13 @@ void CompilerContext::appendInlineAssembly(
 }
 
 
-void CompilerContext::optimizeYul(yul::Object& _object, yul::EVMDialect const& _dialect, OptimiserSettings const& _optimiserSettings, std::set<yul::YulString> const& _externalIdentifiers)
+void CompilerContext::optimizeYul(
+	yul::Object& _object,
+	yul::EVMDialect const& _dialect,
+	OptimiserSettings const& _optimiserSettings,
+	std::set<yul::YulString> const& _externalIdentifiers,
+	bool _system
+)
 {
 #ifdef SOL_OUTPUT_ASM
 	cout << yul::AsmPrinter(*dialect)(*_object.code) << endl;
@@ -539,6 +545,7 @@ void CompilerContext::optimizeYul(yul::Object& _object, yul::EVMDialect const& _
 
 	bool const isCreation = runtimeContext() != nullptr;
 	yul::GasMeter meter(_dialect, isCreation, _optimiserSettings.expectedExecutionsPerDeployment);
+	solAssert(m_freeMemoryInitPush, "");
 	yul::OptimiserSuite::run(
 		_dialect,
 		&meter,
@@ -546,7 +553,8 @@ void CompilerContext::optimizeYul(yul::Object& _object, yul::EVMDialect const& _
 		_optimiserSettings.optimizeStackAllocation,
 		_optimiserSettings.yulOptimiserSteps,
 		isCreation? nullopt : make_optional(_optimiserSettings.expectedExecutionsPerDeployment),
-		_externalIdentifiers
+		_externalIdentifiers,
+		_system ? m_freeMemoryInitPush : shared_ptr<u256>{}
 	);
 
 #ifdef SOL_OUTPUT_ASM

libsolidity/codegen/CompilerContext.h

@@ -276,7 +276,13 @@ public:
 	/// Otherwise returns "revert(0, 0)".
 	std::string revertReasonIfDebug(std::string const& _message = "");
 
-	void optimizeYul(yul::Object& _object, yul::EVMDialect const& _dialect, OptimiserSettings const& _optimiserSetting, std::set<yul::YulString> const& _externalIdentifiers = {});
+	void optimizeYul(
+		yul::Object& _object,
+		yul::EVMDialect const& _dialect,
+		OptimiserSettings const& _optimiserSetting,
+		std::set<yul::YulString> const& _externalIdentifiers = {},
+		bool _system = false
+	);
 
 	/// Appends arbitrary data to the end of the bytecode.
 	void appendToAuxiliaryData(bytes const& _data) { m_asm->appendToAuxiliaryData(_data); }
@@ -309,6 +315,12 @@ public:
 
 	RevertStrings revertStrings() const { return m_revertStrings; }
 
+	evmasm::AssemblyItem makeFreeMemoryInitPush(u256 _value)
+	{
+		m_freeMemoryInitPush = std::make_shared<u256>(_value);
+		return evmasm::AssemblyItem(m_freeMemoryInitPush);
+	}
+
 private:
 	/// Updates source location set in the assembly.
 	void updateSourceLocation();
@@ -394,6 +406,8 @@ 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.
+	std::shared_ptr<u256> 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 << (u256(generalPurposeMemoryStart) + reservedMemory);
+	m_context << m_context.makeFreeMemoryInitPush((u256(generalPurposeMemoryStart) + reservedMemory));
 	storeFreeMemoryPointer();
 }