File reorganisation.

1 files changed, 778 insertions, 0 deletions

diff --git a/libsolidity/codegen/Compiler.cpp b/libsolidity/codegen/Compiler.cpp
new file mode 100644
index 00000000..457b1e02
--- /dev/null
+++ b/libsolidity/codegen/Compiler.cpp
@@ -0,0 +1,778 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum 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.
+
+	cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/**
+ * @author Christian <c@ethdev.com>
+ * @date 2014
+ * Solidity compiler.
+ */
+
+#include <libsolidity/codegen/Compiler.h>
+#include <algorithm>
+#include <boost/range/adaptor/reversed.hpp>
+#include <libevmcore/Instruction.h>
+#include <libevmasm/Assembly.h>
+#include <libevmcore/Params.h>
+#include <libsolidity/ast/AST.h>
+#include <libsolidity/codegen/ExpressionCompiler.h>
+#include <libsolidity/codegen/CompilerUtils.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::solidity;
+
+/**
+ * Simple helper class to ensure that the stack height is the same at certain places in the code.
+ */
+class StackHeightChecker
+{
+public:
+	StackHeightChecker(CompilerContext const& _context):
+		m_context(_context), stackHeight(m_context.stackHeight()) {}
+	void check() { solAssert(m_context.stackHeight() == stackHeight, "I sense a disturbance in the stack."); }
+private:
+	CompilerContext const& m_context;
+	unsigned stackHeight;
+};
+
+void Compiler::compileContract(
+	ContractDefinition const& _contract,
+	std::map<const ContractDefinition*, eth::Assembly const*> const& _contracts
+)
+{
+	m_context = CompilerContext();
+	{
+		CompilerContext::LocationSetter locationSetterRunTime(m_context, _contract);
+		initializeContext(_contract, _contracts);
+		appendFunctionSelector(_contract);
+		appendFunctionsWithoutCode();
+	}
+
+	// Swap the runtime context with the creation-time context
+	swap(m_context, m_runtimeContext);
+	CompilerContext::LocationSetter locationSetterCreationTime(m_context, _contract);
+	initializeContext(_contract, _contracts);
+	packIntoContractCreator(_contract, m_runtimeContext);
+	if (m_optimize)
+		m_context.optimise(m_optimizeRuns);
+
+	if (_contract.isLibrary())
+	{
+		solAssert(m_runtimeSub != size_t(-1), "");
+		m_context.injectVersionStampIntoSub(m_runtimeSub);
+	}
+}
+
+void Compiler::compileClone(
+	ContractDefinition const& _contract,
+	map<ContractDefinition const*, eth::Assembly const*> const& _contracts
+)
+{
+	m_context = CompilerContext(); // clear it just in case
+	initializeContext(_contract, _contracts);
+
+	appendInitAndConstructorCode(_contract);
+
+	//@todo determine largest return size of all runtime functions
+	eth::AssemblyItem runtimeSub = m_context.addSubroutine(cloneRuntime());
+	solAssert(runtimeSub.data() < numeric_limits<size_t>::max(), "");
+	m_runtimeSub = size_t(runtimeSub.data());
+
+	// stack contains sub size
+	m_context << eth::Instruction::DUP1 << runtimeSub << u256(0) << eth::Instruction::CODECOPY;
+	m_context << u256(0) << eth::Instruction::RETURN;
+
+	appendFunctionsWithoutCode();
+
+	if (m_optimize)
+		m_context.optimise(m_optimizeRuns);
+}
+
+eth::AssemblyItem Compiler::functionEntryLabel(FunctionDefinition const& _function) const
+{
+	return m_runtimeContext.functionEntryLabelIfExists(_function);
+}
+
+void Compiler::initializeContext(
+	ContractDefinition const& _contract,
+	map<ContractDefinition const*, eth::Assembly const*> const& _compiledContracts
+)
+{
+	m_context.setCompiledContracts(_compiledContracts);
+	m_context.setInheritanceHierarchy(_contract.annotation().linearizedBaseContracts);
+	CompilerUtils(m_context).initialiseFreeMemoryPointer();
+	registerStateVariables(_contract);
+	m_context.resetVisitedNodes(&_contract);
+}
+
+void Compiler::appendInitAndConstructorCode(ContractDefinition const& _contract)
+{
+	// Determine the arguments that are used for the base constructors.
+	std::vector<ContractDefinition const*> const& bases = _contract.annotation().linearizedBaseContracts;
+	for (ContractDefinition const* contract: bases)
+	{
+		if (FunctionDefinition const* constructor = contract->constructor())
+			for (auto const& modifier: constructor->modifiers())
+			{
+				auto baseContract = dynamic_cast<ContractDefinition const*>(
+					modifier->name()->annotation().referencedDeclaration);
+				if (baseContract)
+					if (m_baseArguments.count(baseContract->constructor()) == 0)
+						m_baseArguments[baseContract->constructor()] = &modifier->arguments();
+			}
+
+		for (ASTPointer<InheritanceSpecifier> const& base: contract->baseContracts())
+		{
+			ContractDefinition const* baseContract = dynamic_cast<ContractDefinition const*>(
+				base->name().annotation().referencedDeclaration
+			);
+			solAssert(baseContract, "");
+
+			if (m_baseArguments.count(baseContract->constructor()) == 0)
+				m_baseArguments[baseContract->constructor()] = &base->arguments();
+		}
+	}
+	// Initialization of state variables in base-to-derived order.
+	for (ContractDefinition const* contract: boost::adaptors::reverse(bases))
+		initializeStateVariables(*contract);
+
+	if (FunctionDefinition const* constructor = _contract.constructor())
+		appendConstructor(*constructor);
+	else if (auto c = m_context.nextConstructor(_contract))
+		appendBaseConstructor(*c);
+}
+
+void Compiler::packIntoContractCreator(ContractDefinition const& _contract, CompilerContext const& _runtimeContext)
+{
+	appendInitAndConstructorCode(_contract);
+
+	eth::AssemblyItem runtimeSub = m_context.addSubroutine(_runtimeContext.assembly());
+	solAssert(runtimeSub.data() < numeric_limits<size_t>::max(), "");
+	m_runtimeSub = size_t(runtimeSub.data());
+
+	// stack contains sub size
+	m_context << eth::Instruction::DUP1 << runtimeSub << u256(0) << eth::Instruction::CODECOPY;
+	m_context << u256(0) << eth::Instruction::RETURN;
+
+	// note that we have to include the functions again because of absolute jump labels
+	appendFunctionsWithoutCode();
+}
+
+void Compiler::appendBaseConstructor(FunctionDefinition const& _constructor)
+{
+	CompilerContext::LocationSetter locationSetter(m_context, _constructor);
+	FunctionType constructorType(_constructor);
+	if (!constructorType.parameterTypes().empty())
+	{
+		solAssert(m_baseArguments.count(&_constructor), "");
+		std::vector<ASTPointer<Expression>> const* arguments = m_baseArguments[&_constructor];
+		solAssert(arguments, "");
+		for (unsigned i = 0; i < arguments->size(); ++i)
+			compileExpression(*(arguments->at(i)), constructorType.parameterTypes()[i]);
+	}
+	_constructor.accept(*this);
+}
+
+void Compiler::appendConstructor(FunctionDefinition const& _constructor)
+{
+	CompilerContext::LocationSetter locationSetter(m_context, _constructor);
+	// copy constructor arguments from code to memory and then to stack, they are supplied after the actual program
+	if (!_constructor.parameters().empty())
+	{
+		unsigned argumentSize = 0;
+		for (ASTPointer<VariableDeclaration> const& var: _constructor.parameters())
+			if (var->annotation().type->isDynamicallySized())
+			{
+				argumentSize = 0;
+				break;
+			}
+			else
+				argumentSize += var->annotation().type->calldataEncodedSize();
+
+		CompilerUtils(m_context).fetchFreeMemoryPointer();
+		if (argumentSize == 0)
+		{
+			// argument size is dynamic, use CODESIZE to determine it
+			m_context.appendProgramSize(); // program itself
+			// CODESIZE is program plus manually added arguments
+			m_context << eth::Instruction::CODESIZE << eth::Instruction::SUB;
+		}
+		else
+			m_context << u256(argumentSize);
+		// stack: <memptr> <argument size>
+		m_context << eth::Instruction::DUP1;
+		m_context.appendProgramSize();
+		m_context << eth::Instruction::DUP4 << eth::Instruction::CODECOPY;
+		m_context << eth::Instruction::DUP2 << eth::Instruction::ADD;
+		CompilerUtils(m_context).storeFreeMemoryPointer();
+		// stack: <memptr>
+		appendCalldataUnpacker(FunctionType(_constructor).parameterTypes(), true);
+	}
+	_constructor.accept(*this);
+}
+
+void Compiler::appendFunctionSelector(ContractDefinition const& _contract)
+{
+	map<FixedHash<4>, FunctionTypePointer> interfaceFunctions = _contract.interfaceFunctions();
+	map<FixedHash<4>, const eth::AssemblyItem> callDataUnpackerEntryPoints;
+
+	FunctionDefinition const* fallback = _contract.fallbackFunction();
+	eth::AssemblyItem notFound = m_context.newTag();
+	// shortcut messages without data if we have many functions in order to be able to receive
+	// ether with constant gas
+	if (interfaceFunctions.size() > 5 || fallback)
+	{
+		m_context << eth::Instruction::CALLDATASIZE << eth::Instruction::ISZERO;
+		m_context.appendConditionalJumpTo(notFound);
+	}
+
+	// retrieve the function signature hash from the calldata
+	if (!interfaceFunctions.empty())
+		CompilerUtils(m_context).loadFromMemory(0, IntegerType(CompilerUtils::dataStartOffset * 8), true);
+
+	// stack now is: 1 0 <funhash>
+	for (auto const& it: interfaceFunctions)
+	{
+		callDataUnpackerEntryPoints.insert(std::make_pair(it.first, m_context.newTag()));
+		m_context << eth::dupInstruction(1) << u256(FixedHash<4>::Arith(it.first)) << eth::Instruction::EQ;
+		m_context.appendConditionalJumpTo(callDataUnpackerEntryPoints.at(it.first));
+	}
+	m_context.appendJumpTo(notFound);
+
+	m_context << notFound;
+	if (fallback)
+	{
+		eth::AssemblyItem returnTag = m_context.pushNewTag();
+		fallback->accept(*this);
+		m_context << returnTag;
+		appendReturnValuePacker(FunctionType(*fallback).returnParameterTypes(), _contract.isLibrary());
+	}
+	else if (_contract.isLibrary())
+		// Reject invalid library calls and ether sent to a library.
+		m_context.appendJumpTo(m_context.errorTag());
+	else
+		m_context << eth::Instruction::STOP; // function not found
+
+	for (auto const& it: interfaceFunctions)
+	{
+		FunctionTypePointer const& functionType = it.second;
+		solAssert(functionType->hasDeclaration(), "");
+		CompilerContext::LocationSetter locationSetter(m_context, functionType->declaration());
+		m_context << callDataUnpackerEntryPoints.at(it.first);
+		eth::AssemblyItem returnTag = m_context.pushNewTag();
+		m_context << CompilerUtils::dataStartOffset;
+		appendCalldataUnpacker(functionType->parameterTypes());
+		m_context.appendJumpTo(m_context.functionEntryLabel(functionType->declaration()));
+		m_context << returnTag;
+		appendReturnValuePacker(functionType->returnParameterTypes(), _contract.isLibrary());
+	}
+}
+
+void Compiler::appendCalldataUnpacker(TypePointers const& _typeParameters, bool _fromMemory)
+{
+	// We do not check the calldata size, everything is zero-padded
+
+	//@todo this does not yet support nested dynamic arrays
+
+	// Retain the offset pointer as base_offset, the point from which the data offsets are computed.
+	m_context << eth::Instruction::DUP1;
+	for (TypePointer const& parameterType: _typeParameters)
+	{
+		// stack: v1 v2 ... v(k-1) base_offset current_offset
+		TypePointer type = parameterType->decodingType();
+		if (type->category() == Type::Category::Array)
+		{
+			auto const& arrayType = dynamic_cast<ArrayType const&>(*type);
+			solAssert(!arrayType.baseType()->isDynamicallySized(), "Nested arrays not yet implemented.");
+			if (_fromMemory)
+			{
+				solAssert(
+					arrayType.baseType()->isValueType(),
+					"Nested memory arrays not yet implemented here."
+				);
+				// @todo If base type is an array or struct, it is still calldata-style encoded, so
+				// we would have to convert it like below.
+				solAssert(arrayType.location() == DataLocation::Memory, "");
+				// compute data pointer
+				m_context << eth::Instruction::DUP1 << eth::Instruction::MLOAD;
+				m_context << eth::Instruction::DUP3 << eth::Instruction::ADD;
+				m_context << eth::Instruction::SWAP2 << eth::Instruction::SWAP1;
+				m_context << u256(0x20) << eth::Instruction::ADD;
+			}
+			else
+			{
+				// first load from calldata and potentially convert to memory if arrayType is memory
+				TypePointer calldataType = arrayType.copyForLocation(DataLocation::CallData, false);
+				if (calldataType->isDynamicallySized())
+				{
+					// put on stack: data_pointer length
+					CompilerUtils(m_context).loadFromMemoryDynamic(IntegerType(256), !_fromMemory);
+					// stack: base_offset data_offset next_pointer
+					m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP3 << eth::Instruction::ADD;
+					// stack: base_offset next_pointer data_pointer
+					// retrieve length
+					CompilerUtils(m_context).loadFromMemoryDynamic(IntegerType(256), !_fromMemory, true);
+					// stack: base_offset next_pointer length data_pointer
+					m_context << eth::Instruction::SWAP2;
+					// stack: base_offset data_pointer length next_pointer
+				}
+				else
+				{
+					// leave the pointer on the stack
+					m_context << eth::Instruction::DUP1;
+					m_context << u256(calldataType->calldataEncodedSize()) << eth::Instruction::ADD;
+				}
+				if (arrayType.location() == DataLocation::Memory)
+				{
+					// stack: base_offset calldata_ref [length] next_calldata
+					// copy to memory
+					// move calldata type up again
+					CompilerUtils(m_context).moveIntoStack(calldataType->sizeOnStack());
+					CompilerUtils(m_context).convertType(*calldataType, arrayType);
+					// fetch next pointer again
+					CompilerUtils(m_context).moveToStackTop(arrayType.sizeOnStack());
+				}
+				// move base_offset up
+				CompilerUtils(m_context).moveToStackTop(1 + arrayType.sizeOnStack());
+				m_context << eth::Instruction::SWAP1;
+			}
+		}
+		else
+		{
+			solAssert(!type->isDynamicallySized(), "Unknown dynamically sized type: " + type->toString());
+			CompilerUtils(m_context).loadFromMemoryDynamic(*type, !_fromMemory, true);
+			CompilerUtils(m_context).moveToStackTop(1 + type->sizeOnStack());
+			m_context << eth::Instruction::SWAP1;
+		}
+		// stack: v1 v2 ... v(k-1) v(k) base_offset mem_offset
+	}
+	m_context << eth::Instruction::POP << eth::Instruction::POP;
+}
+
+void Compiler::appendReturnValuePacker(TypePointers const& _typeParameters, bool _isLibrary)
+{
+	CompilerUtils utils(m_context);
+	if (_typeParameters.empty())
+		m_context << eth::Instruction::STOP;
+	else
+	{
+		utils.fetchFreeMemoryPointer();
+		//@todo optimization: if we return a single memory array, there should be enough space before
+		// its data to add the needed parts and we avoid a memory copy.
+		utils.encodeToMemory(_typeParameters, _typeParameters, true, false, _isLibrary);
+		utils.toSizeAfterFreeMemoryPointer();
+		m_context << eth::Instruction::RETURN;
+	}
+}
+
+void Compiler::registerStateVariables(ContractDefinition const& _contract)
+{
+	for (auto const& var: ContractType(_contract).stateVariables())
+		m_context.addStateVariable(*get<0>(var), get<1>(var), get<2>(var));
+}
+
+void Compiler::initializeStateVariables(ContractDefinition const& _contract)
+{
+	for (ASTPointer<VariableDeclaration> const& variable: _contract.stateVariables())
+		if (variable->value() && !variable->isConstant())
+			ExpressionCompiler(m_context, m_optimize).appendStateVariableInitialization(*variable);
+}
+
+bool Compiler::visit(VariableDeclaration const& _variableDeclaration)
+{
+	solAssert(_variableDeclaration.isStateVariable(), "Compiler visit to non-state variable declaration.");
+	CompilerContext::LocationSetter locationSetter(m_context, _variableDeclaration);
+
+	m_context.startFunction(_variableDeclaration);
+	m_breakTags.clear();
+	m_continueTags.clear();
+
+	if (_variableDeclaration.isConstant())
+		ExpressionCompiler(m_context, m_optimize).appendConstStateVariableAccessor(_variableDeclaration);
+	else
+		ExpressionCompiler(m_context, m_optimize).appendStateVariableAccessor(_variableDeclaration);
+
+	return false;
+}
+
+bool Compiler::visit(FunctionDefinition const& _function)
+{
+	CompilerContext::LocationSetter locationSetter(m_context, _function);
+
+	m_context.startFunction(_function);
+
+	// stack upon entry: [return address] [arg0] [arg1] ... [argn]
+	// reserve additional slots: [retarg0] ... [retargm] [localvar0] ... [localvarp]
+
+	unsigned parametersSize = CompilerUtils::sizeOnStack(_function.parameters());
+	if (!_function.isConstructor())
+		// adding 1 for return address.
+		m_context.adjustStackOffset(parametersSize + 1);
+	for (ASTPointer<VariableDeclaration const> const& variable: _function.parameters())
+	{
+		m_context.addVariable(*variable, parametersSize);
+		parametersSize -= variable->annotation().type->sizeOnStack();
+	}
+
+	for (ASTPointer<VariableDeclaration const> const& variable: _function.returnParameters())
+		appendStackVariableInitialisation(*variable);
+	for (VariableDeclaration const* localVariable: _function.localVariables())
+		appendStackVariableInitialisation(*localVariable);
+
+	if (_function.isConstructor())
+		if (auto c = m_context.nextConstructor(dynamic_cast<ContractDefinition const&>(*_function.scope())))
+			appendBaseConstructor(*c);
+
+	m_returnTag = m_context.newTag();
+	m_breakTags.clear();
+	m_continueTags.clear();
+	m_stackCleanupForReturn = 0;
+	m_currentFunction = &_function;
+	m_modifierDepth = 0;
+
+	appendModifierOrFunctionCode();
+
+	m_context << m_returnTag;
+
+	// Now we need to re-shuffle the stack. For this we keep a record of the stack layout
+	// that shows the target positions of the elements, where "-1" denotes that this element needs
+	// to be removed from the stack.
+	// Note that the fact that the return arguments are of increasing index is vital for this
+	// algorithm to work.
+
+	unsigned const c_argumentsSize = CompilerUtils::sizeOnStack(_function.parameters());
+	unsigned const c_returnValuesSize = CompilerUtils::sizeOnStack(_function.returnParameters());
+	unsigned const c_localVariablesSize = CompilerUtils::sizeOnStack(_function.localVariables());
+
+	vector<int> stackLayout;
+	stackLayout.push_back(c_returnValuesSize); // target of return address
+	stackLayout += vector<int>(c_argumentsSize, -1); // discard all arguments
+	for (unsigned i = 0; i < c_returnValuesSize; ++i)
+		stackLayout.push_back(i);
+	stackLayout += vector<int>(c_localVariablesSize, -1);
+
+	solAssert(stackLayout.size() <= 17, "Stack too deep, try removing local variables.");
+	while (stackLayout.back() != int(stackLayout.size() - 1))
+		if (stackLayout.back() < 0)
+		{
+			m_context << eth::Instruction::POP;
+			stackLayout.pop_back();
+		}
+		else
+		{
+			m_context << eth::swapInstruction(stackLayout.size() - stackLayout.back() - 1);
+			swap(stackLayout[stackLayout.back()], stackLayout.back());
+		}
+	//@todo assert that everything is in place now
+
+	for (ASTPointer<VariableDeclaration const> const& variable: _function.parameters() + _function.returnParameters())
+		m_context.removeVariable(*variable);
+	for (VariableDeclaration const* localVariable: _function.localVariables())
+		m_context.removeVariable(*localVariable);
+
+	m_context.adjustStackOffset(-(int)c_returnValuesSize);
+
+	if (!_function.isConstructor())
+		m_context.appendJump(eth::AssemblyItem::JumpType::OutOfFunction);
+	return false;
+}
+
+bool Compiler::visit(IfStatement const& _ifStatement)
+{
+	StackHeightChecker checker(m_context);
+	CompilerContext::LocationSetter locationSetter(m_context, _ifStatement);
+	compileExpression(_ifStatement.condition());
+	m_context << eth::Instruction::ISZERO;
+	eth::AssemblyItem falseTag = m_context.appendConditionalJump();
+	eth::AssemblyItem endTag = falseTag;
+	_ifStatement.trueStatement().accept(*this);
+	if (_ifStatement.falseStatement())
+	{
+		endTag = m_context.appendJumpToNew();
+		m_context << falseTag;
+		_ifStatement.falseStatement()->accept(*this);
+	}
+	m_context << endTag;
+
+	checker.check();
+	return false;
+}
+
+bool Compiler::visit(WhileStatement const& _whileStatement)
+{
+	StackHeightChecker checker(m_context);
+	CompilerContext::LocationSetter locationSetter(m_context, _whileStatement);
+	eth::AssemblyItem loopStart = m_context.newTag();
+	eth::AssemblyItem loopEnd = m_context.newTag();
+	m_continueTags.push_back(loopStart);
+	m_breakTags.push_back(loopEnd);
+
+	m_context << loopStart;
+	compileExpression(_whileStatement.condition());
+	m_context << eth::Instruction::ISZERO;
+	m_context.appendConditionalJumpTo(loopEnd);
+
+	_whileStatement.body().accept(*this);
+
+	m_context.appendJumpTo(loopStart);
+	m_context << loopEnd;
+
+	m_continueTags.pop_back();
+	m_breakTags.pop_back();
+
+	checker.check();
+	return false;
+}
+
+bool Compiler::visit(ForStatement const& _forStatement)
+{
+	StackHeightChecker checker(m_context);
+	CompilerContext::LocationSetter locationSetter(m_context, _forStatement);
+	eth::AssemblyItem loopStart = m_context.newTag();
+	eth::AssemblyItem loopEnd = m_context.newTag();
+	eth::AssemblyItem loopNext = m_context.newTag();
+	m_continueTags.push_back(loopNext);
+	m_breakTags.push_back(loopEnd);
+
+	if (_forStatement.initializationExpression())
+		_forStatement.initializationExpression()->accept(*this);
+
+	m_context << loopStart;
+
+	// if there is no terminating condition in for, default is to always be true
+	if (_forStatement.condition())
+	{
+		compileExpression(*_forStatement.condition());
+		m_context << eth::Instruction::ISZERO;
+		m_context.appendConditionalJumpTo(loopEnd);
+	}
+
+	_forStatement.body().accept(*this);
+
+	m_context << loopNext;
+
+	// for's loop expression if existing
+	if (_forStatement.loopExpression())
+		_forStatement.loopExpression()->accept(*this);
+
+	m_context.appendJumpTo(loopStart);
+	m_context << loopEnd;
+
+	m_continueTags.pop_back();
+	m_breakTags.pop_back();
+
+	checker.check();
+	return false;
+}
+
+bool Compiler::visit(Continue const& _continueStatement)
+{
+	CompilerContext::LocationSetter locationSetter(m_context, _continueStatement);
+	if (!m_continueTags.empty())
+		m_context.appendJumpTo(m_continueTags.back());
+	return false;
+}
+
+bool Compiler::visit(Break const& _breakStatement)
+{
+	CompilerContext::LocationSetter locationSetter(m_context, _breakStatement);
+	if (!m_breakTags.empty())
+		m_context.appendJumpTo(m_breakTags.back());
+	return false;
+}
+
+bool Compiler::visit(Return const& _return)
+{
+	CompilerContext::LocationSetter locationSetter(m_context, _return);
+	if (Expression const* expression = _return.expression())
+	{
+		solAssert(_return.annotation().functionReturnParameters, "Invalid return parameters pointer.");
+		vector<ASTPointer<VariableDeclaration>> const& returnParameters =
+			_return.annotation().functionReturnParameters->parameters();
+		TypePointers types;
+		for (auto const& retVariable: returnParameters)
+			types.push_back(retVariable->annotation().type);
+
+		TypePointer expectedType = types.size() == 1 ? types.front() : make_shared<TupleType>(types);
+		compileExpression(*expression, expectedType);
+
+		for (auto const& retVariable: boost::adaptors::reverse(returnParameters))
+			CompilerUtils(m_context).moveToStackVariable(*retVariable);
+	}
+	for (unsigned i = 0; i < m_stackCleanupForReturn; ++i)
+		m_context << eth::Instruction::POP;
+	m_context.appendJumpTo(m_returnTag);
+	m_context.adjustStackOffset(m_stackCleanupForReturn);
+	return false;
+}
+
+bool Compiler::visit(Throw const& _throw)
+{
+	CompilerContext::LocationSetter locationSetter(m_context, _throw);
+	m_context.appendJumpTo(m_context.errorTag());
+	return false;
+}
+
+bool Compiler::visit(VariableDeclarationStatement const& _variableDeclarationStatement)
+{
+	StackHeightChecker checker(m_context);
+	CompilerContext::LocationSetter locationSetter(m_context, _variableDeclarationStatement);
+	if (Expression const* expression = _variableDeclarationStatement.initialValue())
+	{
+		CompilerUtils utils(m_context);
+		compileExpression(*expression);
+		TypePointers valueTypes;
+		if (auto tupleType = dynamic_cast<TupleType const*>(expression->annotation().type.get()))
+			valueTypes = tupleType->components();
+		else
+			valueTypes = TypePointers{expression->annotation().type};
+		auto const& assignments = _variableDeclarationStatement.annotation().assignments;
+		solAssert(assignments.size() == valueTypes.size(), "");
+		for (size_t i = 0; i < assignments.size(); ++i)
+		{
+			size_t j = assignments.size() - i - 1;
+			solAssert(!!valueTypes[j], "");
+			VariableDeclaration const* varDecl = assignments[j];
+			if (!varDecl)
+				utils.popStackElement(*valueTypes[j]);
+			else
+			{
+				utils.convertType(*valueTypes[j], *varDecl->annotation().type);
+				utils.moveToStackVariable(*varDecl);
+			}
+		}
+	}
+	checker.check();
+	return false;
+}
+
+bool Compiler::visit(ExpressionStatement const& _expressionStatement)
+{
+	StackHeightChecker checker(m_context);
+	CompilerContext::LocationSetter locationSetter(m_context, _expressionStatement);
+	Expression const& expression = _expressionStatement.expression();
+	compileExpression(expression);
+	CompilerUtils(m_context).popStackElement(*expression.annotation().type);
+	checker.check();
+	return false;
+}
+
+bool Compiler::visit(PlaceholderStatement const& _placeholderStatement)
+{
+	StackHeightChecker checker(m_context);
+	CompilerContext::LocationSetter locationSetter(m_context, _placeholderStatement);
+	++m_modifierDepth;
+	appendModifierOrFunctionCode();
+	--m_modifierDepth;
+	checker.check();
+	return true;
+}
+
+void Compiler::appendFunctionsWithoutCode()
+{
+	set<Declaration const*> functions = m_context.functionsWithoutCode();
+	while (!functions.empty())
+	{
+		for (Declaration const* function: functions)
+		{
+			m_context.setStackOffset(0);
+			function->accept(*this);
+		}
+		functions = m_context.functionsWithoutCode();
+	}
+}
+
+void Compiler::appendModifierOrFunctionCode()
+{
+	solAssert(m_currentFunction, "");
+	if (m_modifierDepth >= m_currentFunction->modifiers().size())
+		m_currentFunction->body().accept(*this);
+	else
+	{
+		ASTPointer<ModifierInvocation> const& modifierInvocation = m_currentFunction->modifiers()[m_modifierDepth];
+
+		// constructor call should be excluded
+		if (dynamic_cast<ContractDefinition const*>(modifierInvocation->name()->annotation().referencedDeclaration))
+		{
+			++m_modifierDepth;
+			appendModifierOrFunctionCode();
+			--m_modifierDepth;
+			return;
+		}
+
+		ModifierDefinition const& modifier = m_context.functionModifier(modifierInvocation->name()->name());
+		CompilerContext::LocationSetter locationSetter(m_context, modifier);
+		solAssert(modifier.parameters().size() == modifierInvocation->arguments().size(), "");
+		for (unsigned i = 0; i < modifier.parameters().size(); ++i)
+		{
+			m_context.addVariable(*modifier.parameters()[i]);
+			compileExpression(
+				*modifierInvocation->arguments()[i],
+				modifier.parameters()[i]->annotation().type
+			);
+		}
+		for (VariableDeclaration const* localVariable: modifier.localVariables())
+			appendStackVariableInitialisation(*localVariable);
+
+		unsigned const c_stackSurplus = CompilerUtils::sizeOnStack(modifier.parameters()) +
+										CompilerUtils::sizeOnStack(modifier.localVariables());
+		m_stackCleanupForReturn += c_stackSurplus;
+
+		modifier.body().accept(*this);
+
+		for (unsigned i = 0; i < c_stackSurplus; ++i)
+			m_context << eth::Instruction::POP;
+		m_stackCleanupForReturn -= c_stackSurplus;
+	}
+}
+
+void Compiler::appendStackVariableInitialisation(VariableDeclaration const& _variable)
+{
+	CompilerContext::LocationSetter location(m_context, _variable);
+	m_context.addVariable(_variable);
+	CompilerUtils(m_context).pushZeroValue(*_variable.annotation().type);
+}
+
+void Compiler::compileExpression(Expression const& _expression, TypePointer const& _targetType)
+{
+	ExpressionCompiler expressionCompiler(m_context, m_optimize);
+	expressionCompiler.compile(_expression);
+	if (_targetType)
+		CompilerUtils(m_context).convertType(*_expression.annotation().type, *_targetType);
+}
+
+eth::Assembly Compiler::cloneRuntime()
+{
+	eth::Assembly a;
+	a << eth::Instruction::CALLDATASIZE;
+	a << u256(0) << eth::Instruction::DUP1 << eth::Instruction::CALLDATACOPY;
+	//@todo adjust for larger return values, make this dynamic.
+	a << u256(0x20) << u256(0) << eth::Instruction::CALLDATASIZE;
+	// unfortunately, we have to send the value again, so that CALLVALUE returns the correct value
+	// in the callcoded contract.
+	a << u256(0) << eth::Instruction::CALLVALUE;
+	// this is the address which has to be substituted by the linker.
+	//@todo implement as special "marker" AssemblyItem.
+	a << u256("0xcafecafecafecafecafecafecafecafecafecafe");
+	a << u256(eth::c_callGas + eth::c_callValueTransferGas + 10) << eth::Instruction::GAS << eth::Instruction::SUB;
+	a << eth::Instruction::CALLCODE;
+	//Propagate error condition (if CALLCODE pushes 0 on stack).
+	a << eth::Instruction::ISZERO;
+	a.appendJumpI(a.errorTag());
+	//@todo adjust for larger return values, make this dynamic.
+	a << u256(0x20) << u256(0) << eth::Instruction::RETURN;
+	return a;
+}