Merge pull request #1122 from ethereum/firstClassFunctions

Functions as first-class types.

10 files changed, 285 insertions, 108 deletions

diff --git a/libsolidity/codegen/Compiler.cpp b/libsolidity/codegen/Compiler.cpp
index 1ae5dda9..54639515 100644
--- a/libsolidity/codegen/Compiler.cpp
+++ b/libsolidity/codegen/Compiler.cpp
@@ -33,14 +33,15 @@ void Compiler::compileContract(
 	std::map<const ContractDefinition*, eth::Assembly const*> const& _contracts
 )
 {
-	ContractCompiler runtimeCompiler(m_runtimeContext, m_optimize);
+	ContractCompiler runtimeCompiler(nullptr, m_runtimeContext, m_optimize);
 	runtimeCompiler.compileContract(_contract, _contracts);
 
-	ContractCompiler creationCompiler(m_context, m_optimize);
-	m_runtimeSub = creationCompiler.compileConstructor(m_runtimeContext, _contract, _contracts);
+	// This might modify m_runtimeContext because it can access runtime functions at
+	// creation time.
+	ContractCompiler creationCompiler(&runtimeCompiler, m_context, m_optimize);
+	m_runtimeSub = creationCompiler.compileConstructor(_contract, _contracts);
 
-	if (m_optimize)
-		m_context.optimise(m_optimizeRuns);
+	m_context.optimise(m_optimize, m_optimizeRuns);
 
 	if (_contract.isLibrary())
 	{
@@ -54,11 +55,11 @@ void Compiler::compileClone(
 	map<ContractDefinition const*, eth::Assembly const*> const& _contracts
 )
 {
-	ContractCompiler cloneCompiler(m_context, m_optimize);
+	ContractCompiler runtimeCompiler(nullptr, m_runtimeContext, m_optimize);
+	ContractCompiler cloneCompiler(&runtimeCompiler, m_context, m_optimize);
 	m_runtimeSub = cloneCompiler.compileClone(_contract, _contracts);
 
-	if (m_optimize)
-		m_context.optimise(m_optimizeRuns);
+	m_context.optimise(m_optimize, m_optimizeRuns);
 }
 
 eth::AssemblyItem Compiler::functionEntryLabel(FunctionDefinition const& _function) const
diff --git a/libsolidity/codegen/Compiler.h b/libsolidity/codegen/Compiler.h
index fccb68a9..4a87de0e 100644
--- a/libsolidity/codegen/Compiler.h
+++ b/libsolidity/codegen/Compiler.h
@@ -35,7 +35,9 @@ class Compiler
 public:
 	explicit Compiler(bool _optimize = false, unsigned _runs = 200):
 		m_optimize(_optimize),
-		m_optimizeRuns(_runs)
+		m_optimizeRuns(_runs),
+		m_runtimeContext(),
+		m_context(&m_runtimeContext)
 	{ }
 
 	void compileContract(
@@ -69,9 +71,9 @@ public:
 private:
 	bool const m_optimize;
 	unsigned const m_optimizeRuns;
-	CompilerContext m_context;
-	size_t m_runtimeSub = size_t(-1); ///< Identifier of the runtime sub-assembly, if present.
 	CompilerContext m_runtimeContext;
+	size_t m_runtimeSub = size_t(-1); ///< Identifier of the runtime sub-assembly, if present.
+	CompilerContext m_context;
 };
 
 }
diff --git a/libsolidity/codegen/CompilerContext.cpp b/libsolidity/codegen/CompilerContext.cpp
index 3ac5bd3c..c76db2a6 100644
--- a/libsolidity/codegen/CompilerContext.cpp
+++ b/libsolidity/codegen/CompilerContext.cpp
@@ -60,8 +60,8 @@ void CompilerContext::startFunction(Declaration const& _function)
 void CompilerContext::addVariable(VariableDeclaration const& _declaration,
 								  unsigned _offsetToCurrent)
 {
-	solAssert(m_asm.deposit() >= 0 && unsigned(m_asm.deposit()) >= _offsetToCurrent, "");
-	m_localVariables[&_declaration] = unsigned(m_asm.deposit()) - _offsetToCurrent;
+	solAssert(m_asm->deposit() >= 0 && unsigned(m_asm->deposit()) >= _offsetToCurrent, "");
+	m_localVariables[&_declaration] = unsigned(m_asm->deposit()) - _offsetToCurrent;
 }
 
 void CompilerContext::removeVariable(VariableDeclaration const& _declaration)
@@ -92,22 +92,22 @@ eth::AssemblyItem CompilerContext::functionEntryLabelIfExists(Declaration const&
 	return m_functionCompilationQueue.entryLabelIfExists(_declaration);
 }
 
-eth::AssemblyItem CompilerContext::virtualFunctionEntryLabel(FunctionDefinition const& _function)
+FunctionDefinition const& CompilerContext::resolveVirtualFunction(FunctionDefinition const& _function)
 {
 	// Libraries do not allow inheritance and their functions can be inlined, so we should not
 	// search the inheritance hierarchy (which will be the wrong one in case the function
 	// is inlined).
 	if (auto scope = dynamic_cast<ContractDefinition const*>(_function.scope()))
 		if (scope->isLibrary())
-			return functionEntryLabel(_function);
+			return _function;
 	solAssert(!m_inheritanceHierarchy.empty(), "No inheritance hierarchy set.");
-	return virtualFunctionEntryLabel(_function, m_inheritanceHierarchy.begin());
+	return resolveVirtualFunction(_function, m_inheritanceHierarchy.begin());
 }
 
-eth::AssemblyItem CompilerContext::superFunctionEntryLabel(FunctionDefinition const& _function, ContractDefinition const& _base)
+FunctionDefinition const& CompilerContext::superFunction(FunctionDefinition const& _function, ContractDefinition const& _base)
 {
 	solAssert(!m_inheritanceHierarchy.empty(), "No inheritance hierarchy set.");
-	return virtualFunctionEntryLabel(_function, superContract(_base));
+	return resolveVirtualFunction(_function, superContract(_base));
 }
 
 FunctionDefinition const* CompilerContext::nextConstructor(ContractDefinition const& _contract) const
@@ -145,12 +145,12 @@ unsigned CompilerContext::baseStackOffsetOfVariable(Declaration const& _declarat
 
 unsigned CompilerContext::baseToCurrentStackOffset(unsigned _baseOffset) const
 {
-	return m_asm.deposit() - _baseOffset - 1;
+	return m_asm->deposit() - _baseOffset - 1;
 }
 
 unsigned CompilerContext::currentToBaseStackOffset(unsigned _offset) const
 {
-	return m_asm.deposit() - _offset - 1;
+	return m_asm->deposit() - _offset - 1;
 }
 
 pair<u256, unsigned> CompilerContext::storageLocationOfVariable(const Declaration& _declaration) const
@@ -217,17 +217,17 @@ void CompilerContext::appendInlineAssembly(
 		return true;
 	};
 
-	solAssert(assembly::InlineAssemblyStack().parseAndAssemble(*assembly, m_asm, identifierAccess), "");
+	solAssert(assembly::InlineAssemblyStack().parseAndAssemble(*assembly, *m_asm, identifierAccess), "");
 }
 
 void CompilerContext::injectVersionStampIntoSub(size_t _subIndex)
 {
-	eth::Assembly& sub = m_asm.sub(_subIndex);
+	eth::Assembly& sub = m_asm->sub(_subIndex);
 	sub.injectStart(Instruction::POP);
 	sub.injectStart(fromBigEndian<u256>(binaryVersion()));
 }
 
-eth::AssemblyItem CompilerContext::virtualFunctionEntryLabel(
+FunctionDefinition const& CompilerContext::resolveVirtualFunction(
 	FunctionDefinition const& _function,
 	vector<ContractDefinition const*>::const_iterator _searchStart
 )
@@ -242,9 +242,9 @@ eth::AssemblyItem CompilerContext::virtualFunctionEntryLabel(
 				!function->isConstructor() &&
 				FunctionType(*function).hasEqualArgumentTypes(functionType)
 			)
-				return functionEntryLabel(*function);
+				return *function;
 	solAssert(false, "Super function " + name + " not found.");
-	return m_asm.newTag(); // not reached
+	return _function; // not reached
 }
 
 vector<ContractDefinition const*>::const_iterator CompilerContext::superContract(ContractDefinition const& _contract) const
@@ -257,7 +257,7 @@ vector<ContractDefinition const*>::const_iterator CompilerContext::superContract
 
 void CompilerContext::updateSourceLocation()
 {
-	m_asm.setSourceLocation(m_visitedNodes.empty() ? SourceLocation() : m_visitedNodes.top()->location());
+	m_asm->setSourceLocation(m_visitedNodes.empty() ? SourceLocation() : m_visitedNodes.top()->location());
 }
 
 eth::AssemblyItem CompilerContext::FunctionCompilationQueue::entryLabel(
diff --git a/libsolidity/codegen/CompilerContext.h b/libsolidity/codegen/CompilerContext.h
index 0c1500b0..8ccbddfd 100644
--- a/libsolidity/codegen/CompilerContext.h
+++ b/libsolidity/codegen/CompilerContext.h
@@ -44,6 +44,14 @@ namespace solidity {
 class CompilerContext
 {
 public:
+	CompilerContext(CompilerContext* _runtimeContext = nullptr):
+		m_asm(std::make_shared<eth::Assembly>()),
+		m_runtimeContext(_runtimeContext)
+	{
+		if (m_runtimeContext)
+			m_runtimeSub = size_t(m_asm->newSub(m_runtimeContext->m_asm).data());
+	}
+
 	void addMagicGlobal(MagicVariableDeclaration const& _declaration);
 	void addStateVariable(VariableDeclaration const& _declaration, u256 const& _storageOffset, unsigned _byteOffset);
 	void addVariable(VariableDeclaration const& _declaration, unsigned _offsetToCurrent = 0);
@@ -52,9 +60,9 @@ public:
 	void setCompiledContracts(std::map<ContractDefinition const*, eth::Assembly const*> const& _contracts) { m_compiledContracts = _contracts; }
 	eth::Assembly const& compiledContract(ContractDefinition const& _contract) const;
 
-	void setStackOffset(int _offset) { m_asm.setDeposit(_offset); }
-	void adjustStackOffset(int _adjustment) { m_asm.adjustDeposit(_adjustment); }
-	unsigned stackHeight() const { solAssert(m_asm.deposit() >= 0, ""); return unsigned(m_asm.deposit()); }
+	void setStackOffset(int _offset) { m_asm->setDeposit(_offset); }
+	void adjustStackOffset(int _adjustment) { m_asm->adjustDeposit(_adjustment); }
+	unsigned stackHeight() const { solAssert(m_asm->deposit() >= 0, ""); return unsigned(m_asm->deposit()); }
 
 	bool isMagicGlobal(Declaration const* _declaration) const { return m_magicGlobals.count(_declaration) != 0; }
 	bool isLocalVariable(Declaration const* _declaration) const;
@@ -67,10 +75,10 @@ public:
 	eth::AssemblyItem functionEntryLabelIfExists(Declaration const& _declaration) const;
 	void setInheritanceHierarchy(std::vector<ContractDefinition const*> const& _hierarchy) { m_inheritanceHierarchy = _hierarchy; }
 	/// @returns the entry label of the given function and takes overrides into account.
-	eth::AssemblyItem virtualFunctionEntryLabel(FunctionDefinition const& _function);
-	/// @returns the entry label of a function that overrides the given declaration from the most derived class just
+	FunctionDefinition const& resolveVirtualFunction(FunctionDefinition const& _function);
+	/// @returns the function that overrides the given declaration from the most derived class just
 	/// above _base in the current inheritance hierarchy.
-	eth::AssemblyItem superFunctionEntryLabel(FunctionDefinition const& _function, ContractDefinition const& _base);
+	FunctionDefinition const& superFunction(FunctionDefinition const& _function, ContractDefinition const& _base);
 	FunctionDefinition const* nextConstructor(ContractDefinition const& _contract) const;
 
 	/// @returns the next function in the queue of functions that are still to be compiled
@@ -95,30 +103,33 @@ public:
 	std::pair<u256, unsigned> storageLocationOfVariable(Declaration const& _declaration) const;
 
 	/// Appends a JUMPI instruction to a new tag and @returns the tag
-	eth::AssemblyItem appendConditionalJump() { return m_asm.appendJumpI().tag(); }
+	eth::AssemblyItem appendConditionalJump() { return m_asm->appendJumpI().tag(); }
 	/// Appends a JUMPI instruction to @a _tag
-	CompilerContext& appendConditionalJumpTo(eth::AssemblyItem const& _tag) { m_asm.appendJumpI(_tag); return *this; }
+	CompilerContext& appendConditionalJumpTo(eth::AssemblyItem const& _tag) { m_asm->appendJumpI(_tag); return *this; }
 	/// Appends a JUMP to a new tag and @returns the tag
-	eth::AssemblyItem appendJumpToNew() { return m_asm.appendJump().tag(); }
+	eth::AssemblyItem appendJumpToNew() { return m_asm->appendJump().tag(); }
 	/// Appends a JUMP to a tag already on the stack
 	CompilerContext&  appendJump(eth::AssemblyItem::JumpType _jumpType = eth::AssemblyItem::JumpType::Ordinary);
 	/// Returns an "ErrorTag"
-	eth::AssemblyItem errorTag() { return m_asm.errorTag(); }
+	eth::AssemblyItem errorTag() { return m_asm->errorTag(); }
 	/// Appends a JUMP to a specific tag
-	CompilerContext& appendJumpTo(eth::AssemblyItem const& _tag) { m_asm.appendJump(_tag); return *this; }
+	CompilerContext& appendJumpTo(eth::AssemblyItem const& _tag) { m_asm->appendJump(_tag); return *this; }
 	/// Appends pushing of a new tag and @returns the new tag.
-	eth::AssemblyItem pushNewTag() { return m_asm.append(m_asm.newPushTag()).tag(); }
+	eth::AssemblyItem pushNewTag() { return m_asm->append(m_asm->newPushTag()).tag(); }
 	/// @returns a new tag without pushing any opcodes or data
-	eth::AssemblyItem newTag() { return m_asm.newTag(); }
+	eth::AssemblyItem newTag() { return m_asm->newTag(); }
 	/// Adds a subroutine to the code (in the data section) and pushes its size (via a tag)
-	/// on the stack. @returns the assembly item corresponding to the pushed subroutine, i.e. its offset.
-	eth::AssemblyItem addSubroutine(eth::Assembly const& _assembly) { return m_asm.appendSubSize(_assembly); }
+	/// on the stack. @returns the pushsub assembly item.
+	eth::AssemblyItem addSubroutine(eth::AssemblyPointer const& _assembly) { auto sub = m_asm->newSub(_assembly); m_asm->append(m_asm->newPushSubSize(size_t(sub.data()))); return sub; }
+	void pushSubroutineSize(size_t _subRoutine) { m_asm->append(m_asm->newPushSubSize(_subRoutine)); }
+	/// Pushes the offset of the subroutine.
+	void pushSubroutineOffset(size_t _subRoutine) { m_asm->append(eth::AssemblyItem(eth::PushSub, _subRoutine)); }
 	/// Pushes the size of the final program
-	void appendProgramSize() { return m_asm.appendProgramSize(); }
+	void appendProgramSize() { m_asm->appendProgramSize(); }
 	/// Adds data to the data section, pushes a reference to the stack
-	eth::AssemblyItem appendData(bytes const& _data) { return m_asm.append(_data); }
+	eth::AssemblyItem appendData(bytes const& _data) { return m_asm->append(_data); }
 	/// Appends the address (virtual, will be filled in by linker) of a library.
-	void appendLibraryAddress(std::string const& _identifier) { m_asm.appendLibraryAddress(_identifier); }
+	void appendLibraryAddress(std::string const& _identifier) { m_asm->appendLibraryAddress(_identifier); }
 	/// Resets the stack of visited nodes with a new stack having only @c _node
 	void resetVisitedNodes(ASTNode const* _node);
 	/// Pops the stack of visited nodes
@@ -127,10 +138,10 @@ public:
 	void pushVisitedNodes(ASTNode const* _node) { m_visitedNodes.push(_node); updateSourceLocation(); }
 
 	/// Append elements to the current instruction list and adjust @a m_stackOffset.
-	CompilerContext& operator<<(eth::AssemblyItem const& _item) { m_asm.append(_item); return *this; }
-	CompilerContext& operator<<(Instruction _instruction) { m_asm.append(_instruction); return *this; }
-	CompilerContext& operator<<(u256 const& _value) { m_asm.append(_value); return *this; }
-	CompilerContext& operator<<(bytes const& _data) { m_asm.append(_data); return *this; }
+	CompilerContext& operator<<(eth::AssemblyItem const& _item) { m_asm->append(_item); return *this; }
+	CompilerContext& operator<<(Instruction _instruction) { m_asm->append(_instruction); return *this; }
+	CompilerContext& operator<<(u256 const& _value) { m_asm->append(_value); return *this; }
+	CompilerContext& operator<<(bytes const& _data) { m_asm->append(_data); return *this; }
 
 	/// Appends inline assembly. @a _replacements are string-matching replacements that are performed
 	/// prior to parsing the inline assembly.
@@ -144,22 +155,27 @@ public:
 	/// Prepends "PUSH <compiler version number> POP"
 	void injectVersionStampIntoSub(size_t _subIndex);
 
-	void optimise(unsigned _runs = 200) { m_asm.optimise(true, true, _runs); }
+	void optimise(bool _fullOptimsation, unsigned _runs = 200) { m_asm->optimise(_fullOptimsation, true, _runs); }
+
+	/// @returns the runtime context if in creation mode and runtime context is set, nullptr otherwise.
+	CompilerContext* runtimeContext() { return m_runtimeContext; }
+	/// @returns the identifier of the runtime subroutine.
+	size_t runtimeSub() const { return m_runtimeSub; }
 
-	eth::Assembly const& assembly() const { return m_asm; }
+	eth::Assembly const& assembly() const { return *m_asm; }
 	/// @returns non-const reference to the underlying assembly. Should be avoided in favour of
 	/// wrappers in this class.
-	eth::Assembly& nonConstAssembly() { return m_asm; }
+	eth::Assembly& nonConstAssembly() { return *m_asm; }
 
 	/// @arg _sourceCodes is the map of input files to source code strings
 	/// @arg _inJsonFormat shows whether the out should be in Json format
 	Json::Value streamAssembly(std::ostream& _stream, StringMap const& _sourceCodes = StringMap(), bool _inJsonFormat = false) const
 	{
-		return m_asm.stream(_stream, "", _sourceCodes, _inJsonFormat);
+		return m_asm->stream(_stream, "", _sourceCodes, _inJsonFormat);
 	}
 
-	eth::LinkerObject const& assembledObject() { return m_asm.assemble(); }
-	eth::LinkerObject const& assembledRuntimeObject(size_t _subIndex) { return m_asm.sub(_subIndex).assemble(); }
+	eth::LinkerObject const& assembledObject() { return m_asm->assemble(); }
+	eth::LinkerObject const& assembledRuntimeObject(size_t _subIndex) { return m_asm->sub(_subIndex).assemble(); }
 
 	/**
 	 * Helper class to pop the visited nodes stack when a scope closes
@@ -172,9 +188,9 @@ public:
 	};
 
 private:
-	/// @returns the entry label of the given function - searches the inheritance hierarchy
-	/// startig from the given point towards the base.
-	eth::AssemblyItem virtualFunctionEntryLabel(
+	/// Searches the inheritance hierarchy towards the base starting from @a _searchStart and returns
+	/// the first function definition that is overwritten by _function.
+	FunctionDefinition const& resolveVirtualFunction(
 		FunctionDefinition const& _function,
 		std::vector<ContractDefinition const*>::const_iterator _searchStart
 	);
@@ -215,7 +231,7 @@ private:
 		mutable std::queue<Declaration const*> m_functionsToCompile;
 	} m_functionCompilationQueue;
 
-	eth::Assembly m_asm;
+	eth::AssemblyPointer m_asm;
 	/// Magic global variables like msg, tx or this, distinguished by type.
 	std::set<Declaration const*> m_magicGlobals;
 	/// Other already compiled contracts to be used in contract creation calls.
@@ -228,6 +244,10 @@ private:
 	std::vector<ContractDefinition const*> m_inheritanceHierarchy;
 	/// Stack of current visited AST nodes, used for location attachment
 	std::stack<ASTNode const*> m_visitedNodes;
+	/// The runtime context if in Creation mode, this is used for generating tags that would be stored into the storage and then used at runtime.
+	CompilerContext *m_runtimeContext;
+	/// The index of the runtime subroutine.
+	size_t m_runtimeSub = -1;
 };
 
 }
diff --git a/libsolidity/codegen/CompilerUtils.cpp b/libsolidity/codegen/CompilerUtils.cpp
index 58d1caa9..bfe5386b 100644
--- a/libsolidity/codegen/CompilerUtils.cpp
+++ b/libsolidity/codegen/CompilerUtils.cpp
@@ -133,6 +133,16 @@ void CompilerUtils::storeInMemoryDynamic(Type const& _type, bool _padToWordBound
 			m_context << u256(str->value().size());
 		m_context << Instruction::ADD;
 	}
+	else if (
+		_type.category() == Type::Category::Function &&
+		dynamic_cast<FunctionType const&>(_type).location() == FunctionType::Location::External
+	)
+	{
+		solUnimplementedAssert(_padToWordBoundaries, "Non-padded store for function not implemented.");
+		combineExternalFunctionType(true);
+		m_context << Instruction::DUP2 << Instruction::MSTORE;
+		m_context << u256(_padToWordBoundaries ? 32 : 24) << Instruction::ADD;
+	}
 	else
 	{
 		unsigned numBytes = prepareMemoryStore(_type, _padToWordBoundaries);
@@ -206,7 +216,8 @@ void CompilerUtils::encodeToMemory(
 			else if (
 				_givenTypes[i]->dataStoredIn(DataLocation::Storage) ||
 				_givenTypes[i]->dataStoredIn(DataLocation::CallData) ||
-				_givenTypes[i]->category() == Type::Category::StringLiteral
+				_givenTypes[i]->category() == Type::Category::StringLiteral ||
+				_givenTypes[i]->category() == Type::Category::Function
 			)
 				type = _givenTypes[i]; // delay conversion
 			else
@@ -304,6 +315,49 @@ void CompilerUtils::memoryCopy()
 	m_context << Instruction::POP; // ignore return value
 }
 
+void CompilerUtils::splitExternalFunctionType(bool _leftAligned)
+{
+	// We have to split the left-aligned <address><function identifier> into two stack slots:
+	// address (right aligned), function identifier (right aligned)
+	if (_leftAligned)
+	{
+		m_context << Instruction::DUP1 << (u256(1) << (64 + 32)) << Instruction::SWAP1 << Instruction::DIV;
+		// <input> <address>
+		m_context << Instruction::SWAP1 << (u256(1) << 64) << Instruction::SWAP1 << Instruction::DIV;
+	}
+	else
+	{
+		m_context << Instruction::DUP1 << (u256(1) << 32) << Instruction::SWAP1 << Instruction::DIV;
+		m_context << ((u256(1) << 160) - 1) << Instruction::AND << Instruction::SWAP1;
+	}
+	m_context << u256(0xffffffffUL) << Instruction::AND;
+}
+
+void CompilerUtils::combineExternalFunctionType(bool _leftAligned)
+{
+	// <address> <function_id>
+	m_context << u256(0xffffffffUL) << Instruction::AND << Instruction::SWAP1;
+	if (!_leftAligned)
+		m_context << ((u256(1) << 160) - 1) << Instruction::AND;
+	m_context << (u256(1) << 32) << Instruction::MUL;
+	m_context << Instruction::OR;
+	if (_leftAligned)
+		m_context << (u256(1) << 64) << Instruction::MUL;
+}
+
+void CompilerUtils::pushCombinedFunctionEntryLabel(Declaration const& _function)
+{
+	m_context << m_context.functionEntryLabel(_function).pushTag();
+	// If there is a runtime context, we have to merge both labels into the same
+	// stack slot in case we store it in storage.
+	if (CompilerContext* rtc = m_context.runtimeContext())
+		m_context <<
+			(u256(1) << 32) <<
+			Instruction::MUL <<
+			rtc->functionEntryLabel(_function).toSubAssemblyTag(m_context.runtimeSub()) <<
+			Instruction::OR;
+}
+
 void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetType, bool _cleanupNeeded)
 {
 	// For a type extension, we need to remove all higher-order bits that we might have ignored in
@@ -678,6 +732,14 @@ void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetTyp
 
 void CompilerUtils::pushZeroValue(Type const& _type)
 {
+	if (auto const* funType = dynamic_cast<FunctionType const*>(&_type))
+	{
+		if (funType->location() == FunctionType::Location::Internal)
+		{
+			m_context << m_context.errorTag();
+			return;
+		}
+	}
 	auto const* referenceType = dynamic_cast<ReferenceType const*>(&_type);
 	if (!referenceType || referenceType->location() == DataLocation::Storage)
 	{
@@ -822,21 +884,27 @@ void CompilerUtils::storeStringData(bytesConstRef _data)
 unsigned CompilerUtils::loadFromMemoryHelper(Type const& _type, bool _fromCalldata, bool _padToWordBoundaries)
 {
 	unsigned numBytes = _type.calldataEncodedSize(_padToWordBoundaries);
-	bool leftAligned = _type.category() == Type::Category::FixedBytes;
+	bool isExternalFunctionType = false;
+	if (auto const* funType = dynamic_cast<FunctionType const*>(&_type))
+		if (funType->location() == FunctionType::Location::External)
+			isExternalFunctionType = true;
 	if (numBytes == 0)
+	{
 		m_context << Instruction::POP << u256(0);
-	else
+		return numBytes;
+	}
+	solAssert(numBytes <= 32, "Static memory load of more than 32 bytes requested.");
+	m_context << (_fromCalldata ? Instruction::CALLDATALOAD : Instruction::MLOAD);
+	if (isExternalFunctionType)
+		splitExternalFunctionType(true);
+	else if (numBytes != 32)
 	{
-		solAssert(numBytes <= 32, "Static memory load of more than 32 bytes requested.");
-		m_context << (_fromCalldata ? Instruction::CALLDATALOAD : Instruction::MLOAD);
-		if (numBytes != 32)
-		{
-			// add leading or trailing zeros by dividing/multiplying depending on alignment
-			u256 shiftFactor = u256(1) << ((32 - numBytes) * 8);
-			m_context << shiftFactor << Instruction::SWAP1 << Instruction::DIV;
-			if (leftAligned)
-				m_context << shiftFactor << Instruction::MUL;
-		}
+		bool leftAligned = _type.category() == Type::Category::FixedBytes;
+		// add leading or trailing zeros by dividing/multiplying depending on alignment
+		u256 shiftFactor = u256(1) << ((32 - numBytes) * 8);
+		m_context << shiftFactor << Instruction::SWAP1 << Instruction::DIV;
+		if (leftAligned)
+			m_context << shiftFactor << Instruction::MUL;
 	}
 
 	return numBytes;
diff --git a/libsolidity/codegen/CompilerUtils.h b/libsolidity/codegen/CompilerUtils.h
index da74dc90..8e4033d6 100644
--- a/libsolidity/codegen/CompilerUtils.h
+++ b/libsolidity/codegen/CompilerUtils.h
@@ -114,6 +114,17 @@ public:
 	/// Stack post:
 	void memoryCopy();
 
+	/// Converts the combined and left-aligned (right-aligned if @a _rightAligned is true)
+	/// external function type <address><function identifier> into two stack slots:
+	/// address (right aligned), function identifier (right aligned)
+	void splitExternalFunctionType(bool _rightAligned);
+	/// Performs the opposite operation of splitExternalFunctionType(_rightAligned)
+	void combineExternalFunctionType(bool _rightAligned);
+	/// Appends code that combines the construction-time (if available) and runtime function
+	/// entry label of the given function into a single stack slot.
+	/// Note: This might cause the compilation queue of the runtime context to be extended.
+	void pushCombinedFunctionEntryLabel(Declaration const& _function);
+
 	/// Appends code for an implicit or explicit type conversion. This includes erasing higher
 	/// order bits (@see appendHighBitCleanup) when widening integer but also copy to memory
 	/// if a reference type is converted from calldata or storage to memory.
diff --git a/libsolidity/codegen/ContractCompiler.cpp b/libsolidity/codegen/ContractCompiler.cpp
index 2aec3055..2e3f5d7f 100644
--- a/libsolidity/codegen/ContractCompiler.cpp
+++ b/libsolidity/codegen/ContractCompiler.cpp
@@ -60,14 +60,13 @@ void ContractCompiler::compileContract(
 }
 
 size_t ContractCompiler::compileConstructor(
-	CompilerContext const& _runtimeContext,
 	ContractDefinition const& _contract,
 	std::map<const ContractDefinition*, eth::Assembly const*> const& _contracts
 )
 {
 	CompilerContext::LocationSetter locationSetter(m_context, _contract);
 	initializeContext(_contract, _contracts);
-	return packIntoContractCreator(_contract, _runtimeContext);
+	return packIntoContractCreator(_contract);
 }
 
 size_t ContractCompiler::compileClone(
@@ -80,7 +79,7 @@ size_t ContractCompiler::compileClone(
 	appendInitAndConstructorCode(_contract);
 
 	//@todo determine largest return size of all runtime functions
-	eth::AssemblyItem runtimeSub = m_context.addSubroutine(cloneRuntime());
+	auto runtimeSub = m_context.addSubroutine(cloneRuntime());
 
 	// stack contains sub size
 	m_context << Instruction::DUP1 << runtimeSub << u256(0) << Instruction::CODECOPY;
@@ -88,7 +87,6 @@ size_t ContractCompiler::compileClone(
 
 	appendMissingFunctions();
 
-	solAssert(runtimeSub.data() < numeric_limits<size_t>::max(), "");
 	return size_t(runtimeSub.data());
 }
 
@@ -141,21 +139,31 @@ void ContractCompiler::appendInitAndConstructorCode(ContractDefinition const& _c
 		appendBaseConstructor(*c);
 }
 
-size_t ContractCompiler::packIntoContractCreator(ContractDefinition const& _contract, CompilerContext const& _runtimeContext)
+size_t ContractCompiler::packIntoContractCreator(ContractDefinition const& _contract)
 {
+	solAssert(!!m_runtimeCompiler, "");
+
 	appendInitAndConstructorCode(_contract);
 
-	eth::AssemblyItem runtimeSub = m_context.addSubroutine(_runtimeContext.assembly());
+	// We jump to the deploy routine because we first have to append all missing functions,
+	// which can cause further functions to be added to the runtime context.
+	eth::AssemblyItem deployRoutine = m_context.appendJumpToNew();
 
-	// stack contains sub size
-	m_context << Instruction::DUP1 << runtimeSub << u256(0) << Instruction::CODECOPY;
-	m_context << u256(0) << Instruction::RETURN;
-
-	// note that we have to include the functions again because of absolute jump labels
+	// We have to include copies of functions in the construction time and runtime context
+	// because of absolute jumps.
 	appendMissingFunctions();
+	m_runtimeCompiler->appendMissingFunctions();
 
-	solAssert(runtimeSub.data() < numeric_limits<size_t>::max(), "");
-	return size_t(runtimeSub.data());
+	m_context << deployRoutine;
+
+	solAssert(m_context.runtimeSub() != size_t(-1), "Runtime sub not registered");
+	m_context.pushSubroutineSize(m_context.runtimeSub());
+	m_context << Instruction::DUP1;
+	m_context.pushSubroutineOffset(m_context.runtimeSub());
+	m_context << u256(0) << Instruction::CODECOPY;
+	m_context << u256(0) << Instruction::RETURN;
+
+	return m_context.runtimeSub();
 }
 
 void ContractCompiler::appendBaseConstructor(FunctionDefinition const& _constructor)
@@ -293,6 +301,7 @@ void ContractCompiler::appendCalldataUnpacker(TypePointers const& _typeParameter
 	{
 		// stack: v1 v2 ... v(k-1) base_offset current_offset
 		TypePointer type = parameterType->decodingType();
+		solAssert(type, "No decoding type found.");
 		if (type->category() == Type::Category::Array)
 		{
 			auto const& arrayType = dynamic_cast<ArrayType const&>(*type);
@@ -515,7 +524,19 @@ bool ContractCompiler::visit(InlineAssembly const& _inlineAssembly)
 			{
 				solAssert(!!decl->type(), "Type of declaration required but not yet determined.");
 				if (FunctionDefinition const* functionDef = dynamic_cast<FunctionDefinition const*>(decl))
-					_assembly.append(m_context.virtualFunctionEntryLabel(*functionDef).pushTag());
+				{
+					functionDef = &m_context.resolveVirtualFunction(*functionDef);
+					_assembly.append(m_context.functionEntryLabel(*functionDef).pushTag());
+					// If there is a runtime context, we have to merge both labels into the same
+					// stack slot in case we store it in storage.
+					if (CompilerContext* rtc = m_context.runtimeContext())
+					{
+						_assembly.append(u256(1) << 32);
+						_assembly.append(Instruction::MUL);
+						_assembly.append(rtc->functionEntryLabel(*functionDef).toSubAssemblyTag(m_context.runtimeSub()));
+						_assembly.append(Instruction::OR);
+					}
+				}
 				else if (auto variable = dynamic_cast<VariableDeclaration const*>(decl))
 				{
 					solAssert(!variable->isConstant(), "");
@@ -871,7 +892,7 @@ void ContractCompiler::compileExpression(Expression const& _expression, TypePoin
 		CompilerUtils(m_context).convertType(*_expression.annotation().type, *_targetType);
 }
 
-eth::Assembly ContractCompiler::cloneRuntime()
+eth::AssemblyPointer ContractCompiler::cloneRuntime()
 {
 	eth::Assembly a;
 	a << Instruction::CALLDATASIZE;
@@ -889,5 +910,5 @@ eth::Assembly ContractCompiler::cloneRuntime()
 	a.appendJumpI(a.errorTag());
 	//@todo adjust for larger return values, make this dynamic.
 	a << u256(0x20) << u256(0) << Instruction::RETURN;
-	return a;
+	return make_shared<eth::Assembly>(a);
 }
diff --git a/libsolidity/codegen/ContractCompiler.h b/libsolidity/codegen/ContractCompiler.h
index 0799a543..2244a3be 100644
--- a/libsolidity/codegen/ContractCompiler.h
+++ b/libsolidity/codegen/ContractCompiler.h
@@ -38,11 +38,12 @@ namespace solidity {
 class ContractCompiler: private ASTConstVisitor
 {
 public:
-	explicit ContractCompiler(CompilerContext& _context, bool _optimise):
+	explicit ContractCompiler(ContractCompiler* _runtimeCompiler, CompilerContext& _context, bool _optimise):
 		m_optimise(_optimise),
+		m_runtimeCompiler(_runtimeCompiler),
 		m_context(_context)
 	{
-		m_context = CompilerContext();
+		m_context = CompilerContext(_runtimeCompiler ? &_runtimeCompiler->m_context : nullptr);
 	}
 
 	void compileContract(
@@ -52,7 +53,6 @@ public:
 	/// Compiles the constructor part of the contract.
 	/// @returns the identifier of the runtime sub-assembly.
 	size_t compileConstructor(
-		CompilerContext const& _runtimeContext,
 		ContractDefinition const& _contract,
 		std::map<ContractDefinition const*, eth::Assembly const*> const& _contracts
 	);
@@ -74,7 +74,7 @@ private:
 	/// Adds the code that is run at creation time. Should be run after exchanging the run-time context
 	/// with a new and initialized context. Adds the constructor code.
 	/// @returns the identifier of the runtime sub assembly
-	size_t packIntoContractCreator(ContractDefinition const& _contract, CompilerContext const& _runtimeContext);
+	size_t packIntoContractCreator(ContractDefinition const& _contract);
 	/// Appends state variable initialisation and constructor code.
 	void appendInitAndConstructorCode(ContractDefinition const& _contract);
 	void appendBaseConstructor(FunctionDefinition const& _constructor);
@@ -114,9 +114,11 @@ private:
 	void compileExpression(Expression const& _expression, TypePointer const& _targetType = TypePointer());
 
 	/// @returns the runtime assembly for clone contracts.
-	static eth::Assembly cloneRuntime();
+	static eth::AssemblyPointer cloneRuntime();
 
 	bool const m_optimise;
+	/// Pointer to the runtime compiler in case this is a creation compiler.
+	ContractCompiler* m_runtimeCompiler = nullptr;
 	CompilerContext& m_context;
 	std::vector<eth::AssemblyItem> m_breakTags; ///< tag to jump to for a "break" statement
 	std::vector<eth::AssemblyItem> m_continueTags; ///< tag to jump to for a "continue" statement
diff --git a/libsolidity/codegen/ExpressionCompiler.cpp b/libsolidity/codegen/ExpressionCompiler.cpp
index e3f05c21..7a328528 100644
--- a/libsolidity/codegen/ExpressionCompiler.cpp
+++ b/libsolidity/codegen/ExpressionCompiler.cpp
@@ -488,6 +488,13 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 				parameterSize += function.selfType()->sizeOnStack();
 			}
 
+			if (m_context.runtimeContext())
+				// We have a runtime context, so we need the creation part.
+				m_context << (u256(1) << 32) << Instruction::SWAP1 << Instruction::DIV;
+			else
+				// Extract the runtime part.
+				m_context << ((u256(1) << 32) - 1) << Instruction::AND;
+
 			m_context.appendJump(eth::AssemblyItem::JumpType::IntoFunction);
 			m_context << returnLabel;
 
@@ -521,8 +528,11 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			// copy the contract's code into memory
 			eth::Assembly const& assembly = m_context.compiledContract(contract);
 			utils().fetchFreeMemoryPointer();
+			// TODO we create a copy here, which is actually what we want.
+			// This should be revisited at the point where we fix
+			// https://github.com/ethereum/solidity/issues/1092
 			// pushes size
-			eth::AssemblyItem subroutine = m_context.addSubroutine(assembly);
+			auto subroutine = m_context.addSubroutine(make_shared<eth::Assembly>(assembly));
 			m_context << Instruction::DUP1 << subroutine;
 			m_context << Instruction::DUP4 << Instruction::CODECOPY;
 
@@ -845,9 +855,8 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 			);
 			if (funType->location() == FunctionType::Location::Internal)
 			{
-				m_context << m_context.functionEntryLabel(
-					dynamic_cast<FunctionDefinition const&>(funType->declaration())
-				).pushTag();
+				FunctionDefinition const& funDef = dynamic_cast<decltype(funDef)>(funType->declaration());
+				utils().pushCombinedFunctionEntryLabel(funDef);
 				utils().moveIntoStack(funType->selfType()->sizeOnStack(), 1);
 			}
 			else
@@ -883,7 +892,7 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 					// us to link against it although we actually do not need it.
 					auto const* function = dynamic_cast<FunctionDefinition const*>(_memberAccess.annotation().referencedDeclaration);
 					solAssert(!!function, "Function not found in member access");
-					m_context << m_context.functionEntryLabel(*function).pushTag();
+					utils().pushCombinedFunctionEntryLabel(*function);
 				}
 			}
 			else if (dynamic_cast<TypeType const*>(_memberAccess.annotation().type.get()))
@@ -915,10 +924,10 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 		if (type.isSuper())
 		{
 			solAssert(!!_memberAccess.annotation().referencedDeclaration, "Referenced declaration not resolved.");
-			m_context << m_context.superFunctionEntryLabel(
+			utils().pushCombinedFunctionEntryLabel(m_context.superFunction(
 				dynamic_cast<FunctionDefinition const&>(*_memberAccess.annotation().referencedDeclaration),
 				type.contractDefinition()
-			).pushTag();
+			));
 		}
 		else
 		{
@@ -1203,7 +1212,7 @@ void ExpressionCompiler::endVisit(Identifier const& _identifier)
 		}
 	}
 	else if (FunctionDefinition const* functionDef = dynamic_cast<FunctionDefinition const*>(declaration))
-		m_context << m_context.virtualFunctionEntryLabel(*functionDef).pushTag();
+		utils().pushCombinedFunctionEntryLabel(m_context.resolveVirtualFunction(*functionDef));
 	else if (auto variable = dynamic_cast<VariableDeclaration const*>(declaration))
 		appendVariable(*variable, static_cast<Expression const&>(_identifier));
 	else if (auto contract = dynamic_cast<ContractDefinition const*>(declaration))
@@ -1266,6 +1275,17 @@ void ExpressionCompiler::appendCompareOperatorCode(Token::Value _operator, Type
 {
 	if (_operator == Token::Equal || _operator == Token::NotEqual)
 	{
+		if (FunctionType const* funType = dynamic_cast<decltype(funType)>(&_type))
+		{
+			if (funType->location() == FunctionType::Location::Internal)
+			{
+				// We have to remove the upper bits (construction time value) because they might
+				// be "unknown" in one of the operands and not in the other.
+				m_context << ((u256(1) << 32) - 1) << Instruction::AND;
+				m_context << Instruction::SWAP1;
+				m_context << ((u256(1) << 32) - 1) << Instruction::AND;
+			}
+		}
 		m_context << Instruction::EQ;
 		if (_operator == Token::NotEqual)
 			m_context << Instruction::ISZERO;
diff --git a/libsolidity/codegen/LValue.cpp b/libsolidity/codegen/LValue.cpp
index 69a80b6a..2ec7f800 100644
--- a/libsolidity/codegen/LValue.cpp
+++ b/libsolidity/codegen/LValue.cpp
@@ -153,7 +153,8 @@ StorageItem::StorageItem(CompilerContext& _compilerContext, Type const& _type):
 {
 	if (m_dataType->isValueType())
 	{
-		solAssert(m_dataType->storageSize() == m_dataType->sizeOnStack(), "");
+		if (m_dataType->category() != Type::Category::Function)
+			solAssert(m_dataType->storageSize() == m_dataType->sizeOnStack(), "");
 		solAssert(m_dataType->storageSize() == 1, "Invalid storage size.");
 	}
 }
@@ -176,6 +177,7 @@ void StorageItem::retrieveValue(SourceLocation const&, bool _remove) const
 		m_context << Instruction::POP << Instruction::SLOAD;
 	else
 	{
+		bool cleaned = false;
 		m_context
 			<< Instruction::SWAP1 << Instruction::SLOAD << Instruction::SWAP1
 			<< u256(0x100) << Instruction::EXP << Instruction::SWAP1 << Instruction::DIV;
@@ -183,14 +185,31 @@ void StorageItem::retrieveValue(SourceLocation const&, bool _remove) const
 			// implementation should be very similar to the integer case.
 			solUnimplemented("Not yet implemented - FixedPointType.");
 		if (m_dataType->category() == Type::Category::FixedBytes)
+		{
 			m_context << (u256(0x1) << (256 - 8 * m_dataType->storageBytes())) << Instruction::MUL;
+			cleaned = true;
+		}
 		else if (
 			m_dataType->category() == Type::Category::Integer &&
 			dynamic_cast<IntegerType const&>(*m_dataType).isSigned()
 		)
+		{
 			m_context << u256(m_dataType->storageBytes() - 1) << Instruction::SIGNEXTEND;
-		else
+			cleaned = true;
+		}
+		else if (FunctionType const* fun = dynamic_cast<decltype(fun)>(m_dataType))
+		{
+			if (fun->location() == FunctionType::Location::External)
+			{
+				CompilerUtils(m_context).splitExternalFunctionType(false);
+				cleaned = true;
+			}
+		}
+		if (!cleaned)
+		{
+			solAssert(m_dataType->sizeOnStack() == 1, "");
 			m_context << ((u256(0x1) << (8 * m_dataType->storageBytes())) - 1) << Instruction::AND;
+		}
 	}
 }
 
@@ -204,6 +223,7 @@ void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _loc
 		solAssert(m_dataType->storageBytes() > 0, "Invalid storage bytes size.");
 		if (m_dataType->storageBytes() == 32)
 		{
+			solAssert(m_dataType->sizeOnStack() == 1, "Invalid stack size.");
 			// offset should be zero
 			m_context << Instruction::POP;
 			if (!_move)
@@ -222,16 +242,27 @@ void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _loc
 			m_context
 				<< Instruction::DUP2 << ((u256(1) << (8 * m_dataType->storageBytes())) - 1)
 				<< Instruction::MUL;
-			m_context << Instruction::NOT << Instruction::AND;
-			// stack: value storage_ref multiplier cleared_value
-			m_context
-				<< Instruction::SWAP1 << Instruction::DUP4;
+			m_context << Instruction::NOT << Instruction::AND << Instruction::SWAP1;
+			// stack: value storage_ref cleared_value multiplier
+			utils.copyToStackTop(3 + m_dataType->sizeOnStack(), m_dataType->sizeOnStack());
 			// stack: value storage_ref cleared_value multiplier value
-			if (m_dataType->category() == Type::Category::FixedBytes)
+			if (FunctionType const* fun = dynamic_cast<decltype(fun)>(m_dataType))
+			{
+				if (fun->location() == FunctionType::Location::External)
+					// Combine the two-item function type into a single stack slot.
+					utils.combineExternalFunctionType(false);
+				else
+					m_context <<
+						((u256(1) << (8 * m_dataType->storageBytes())) - 1) <<
+						Instruction::AND;
+			}
+			else if (m_dataType->category() == Type::Category::FixedBytes)
 				m_context
 					<< (u256(0x1) << (256 - 8 * dynamic_cast<FixedBytesType const&>(*m_dataType).numBytes()))
 					<< Instruction::SWAP1 << Instruction::DIV;
 			else
+			{
+				solAssert(m_dataType->sizeOnStack() == 1, "Invalid stack size for opaque type.");
 				// remove the higher order bits
 				m_context
 					<< (u256(1) << (8 * (32 - m_dataType->storageBytes())))
@@ -239,11 +270,12 @@ void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _loc
 					<< Instruction::DUP2
 					<< Instruction::MUL
 					<< Instruction::DIV;
+			}
 			m_context  << Instruction::MUL << Instruction::OR;
 			// stack: value storage_ref updated_value
 			m_context << Instruction::SWAP1 << Instruction::SSTORE;
 			if (_move)
-				m_context << Instruction::POP;
+				utils.popStackElement(*m_dataType);
 		}
 	}
 	else