Merge pull request #2199 from chriseth/sol_memoryArrays4

Copying between memory and memory.

libsolidity/Compiler.cpp

@@ -30,9 +30,8 @@
 #include <libsolidity/CompilerUtils.h>
 
 using namespace std;
-
-namespace dev {
-namespace solidity {
+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.
@@ -301,24 +300,18 @@ void Compiler::appendCalldataUnpacker(
 
 void Compiler::appendReturnValuePacker(TypePointers const& _typeParameters)
 {
-	unsigned dataOffset = 0;
-	unsigned stackDepth = 0;
-	for (TypePointer const& type: _typeParameters)
-		stackDepth += type->getSizeOnStack();
-
-	for (TypePointer const& type: _typeParameters)
-	{
-		CompilerUtils(m_context).copyToStackTop(stackDepth, type->getSizeOnStack());
-		ExpressionCompiler(m_context, m_optimize).appendTypeConversion(*type, *type, true);
-		bool const c_padToWords = true;
-		dataOffset += CompilerUtils(m_context).storeInMemory(dataOffset, *type, c_padToWords);
-		stackDepth -= type->getSizeOnStack();
-	}
-	// note that the stack is not cleaned up here
-	if (dataOffset == 0)
+	CompilerUtils utils(m_context);
+	if (_typeParameters.empty())
 		m_context << eth::Instruction::STOP;
 	else
-		m_context << u256(dataOffset) << u256(0) << eth::Instruction::RETURN;
+	{
+		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);
+		utils.toSizeAfterFreeMemoryPointer();
+		m_context << eth::Instruction::RETURN;
+	}
 }
 
 void Compiler::registerStateVariables(ContractDefinition const& _contract)
@@ -634,8 +627,5 @@ void Compiler::compileExpression(Expression const& _expression, TypePointer cons
 	ExpressionCompiler expressionCompiler(m_context, m_optimize);
 	expressionCompiler.compile(_expression);
 	if (_targetType)
-		expressionCompiler.appendTypeConversion(*_expression.getType(), *_targetType);
-}
-
-}
+		CompilerUtils(m_context).convertType(*_expression.getType(), *_targetType);
 }

libsolidity/CompilerUtils.cpp

@@ -23,6 +23,8 @@
 #include <libsolidity/CompilerUtils.h>
 #include <libsolidity/AST.h>
 #include <libevmcore/Instruction.h>
+#include <libevmcore/Params.h>
+#include <libsolidity/ArrayUtils.h>
 
 using namespace std;
 
@@ -33,6 +35,7 @@ namespace solidity
 
 const unsigned CompilerUtils::dataStartOffset = 4;
 const size_t CompilerUtils::freeMemoryPointer = 64;
+const unsigned CompilerUtils::identityContractAddress = 4;
 
 void CompilerUtils::initialiseFreeMemoryPointer()
 {
@@ -83,8 +86,7 @@ void CompilerUtils::loadFromMemoryDynamic(
 	if (_keepUpdatedMemoryOffset)
 	{
 		// update memory counter
-		for (unsigned i = 0; i < _type.getSizeOnStack(); ++i)
-			m_context << eth::swapInstruction(1 + i);
+		moveToStackTop(_type.getSizeOnStack());
 		m_context << u256(numBytes) << eth::Instruction::ADD;
 	}
 }
@@ -108,15 +110,80 @@ void CompilerUtils::storeInMemoryDynamic(Type const& _type, bool _padToWordBound
 		if (type.location() == ReferenceType::Location::CallData)
 		{
 			// stack: target source_offset source_len
-			m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3 << eth::Instruction::DUP5
+			m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3 << eth::Instruction::DUP5;
 				// stack: target source_offset source_len source_len source_offset target
-				<< eth::Instruction::CALLDATACOPY
-				<< eth::Instruction::DUP3 << eth::Instruction::ADD
-				<< eth::Instruction::SWAP2 << eth::Instruction::POP << eth::Instruction::POP;
+			m_context << eth::Instruction::CALLDATACOPY;
+			m_context << eth::Instruction::DUP3 << eth::Instruction::ADD;
+			m_context << eth::Instruction::SWAP2 << eth::Instruction::POP << eth::Instruction::POP;
+		}
+		else if (type.location() == ReferenceType::Location::Memory)
+		{
+			// memcpy using the built-in contract
+			ArrayUtils(m_context).retrieveLength(type);
+			if (type.isDynamicallySized())
+			{
+				// change pointer to data part
+				m_context << eth::Instruction::SWAP1 << u256(32) << eth::Instruction::ADD;
+				m_context << eth::Instruction::SWAP1;
+			}
+			// stack: <target> <source> <length>
+			// stack for call: outsize target size source value contract gas
+			m_context << eth::Instruction::DUP1 << eth::Instruction::DUP4;
+			m_context << eth::Instruction::DUP2 << eth::Instruction::DUP5;
+			m_context << u256(0) << u256(identityContractAddress);
+			//@TODO do not use ::CALL if less than 32 bytes?
+			//@todo in production, we should not have to pair c_callNewAccountGas.
+			m_context << u256(eth::c_callGas + 10 + eth::c_callNewAccountGas) << eth::Instruction::GAS;
+			m_context << eth::Instruction::SUB << eth::Instruction::CALL;
+			m_context << eth::Instruction::POP; // ignore return value
+
+			m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
+			// stack: <target> <length>
+
+			if (_padToWordBoundaries && (type.isDynamicallySized() || (type.getLength()) % 32 != 0))
+			{
+				// stack: <target> <length>
+				m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2 << eth::Instruction::ADD;
+				// stack: <length> <target + length>
+				m_context << eth::Instruction::SWAP1 << u256(31) << eth::Instruction::AND;
+				// stack: <target + length> <remainder = length % 32>
+				eth::AssemblyItem skip = m_context.newTag();
+				if (type.isDynamicallySized())
+				{
+					m_context << eth::Instruction::DUP1 << eth::Instruction::ISZERO;
+					m_context.appendConditionalJumpTo(skip);
+				}
+				// round off, load from there.
+				// stack <target + length> <remainder = length % 32>
+				m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3;
+				m_context << eth::Instruction::SUB;
+				// stack: target+length remainder <target + length - remainder>
+				m_context << eth::Instruction::DUP1 << eth::Instruction::MLOAD;
+				// Now we AND it with ~(2**(8 * (32 - remainder)) - 1)
+				m_context << u256(1);
+				m_context << eth::Instruction::DUP4 << u256(32) << eth::Instruction::SUB;
+				// stack: ...<v> 1 <32 - remainder>
+				m_context << u256(0x100) << eth::Instruction::EXP << eth::Instruction::SUB;
+				m_context << eth::Instruction::NOT << eth::Instruction::AND;
+				// stack: target+length remainder target+length-remainder <v & ...>
+				m_context << eth::Instruction::DUP2 << eth::Instruction::MSTORE;
+				// stack: target+length remainder target+length-remainder
+				m_context << u256(32) << eth::Instruction::ADD;
+				// stack: target+length remainder <new_padded_end>
+				m_context << eth::Instruction::SWAP2 << eth::Instruction::POP;
+
+				if (type.isDynamicallySized())
+					m_context << skip.tag();
+				// stack <target + "length"> <remainder = length % 32>
+				m_context << eth::Instruction::POP;
+			}
+			else
+				// stack: <target> <length>
+				m_context << eth::Instruction::ADD;
 		}
 		else
 		{
-			solAssert(type.location() == ReferenceType::Location::Storage, "Memory arrays not yet implemented.");
+			solAssert(type.location() == ReferenceType::Location::Storage, "");
 			m_context << eth::Instruction::POP; // remove offset, arrays always start new slot
 			m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD;
 			// stack here: memory_offset storage_offset length_bytes
@@ -133,17 +200,28 @@ void CompilerUtils::storeInMemoryDynamic(Type const& _type, bool _padToWordBound
 
 			// stack here: memory_end_offset storage_data_offset memory_offset
 			eth::AssemblyItem loopStart = m_context.newTag();
-			m_context << loopStart
-					  // load and store
-					  << eth::Instruction::DUP2 << eth::Instruction::SLOAD
-					  << eth::Instruction::DUP2 << eth::Instruction::MSTORE
-					  // increment storage_data_offset by 1
-					  << eth::Instruction::SWAP1 << u256(1) << eth::Instruction::ADD
-					  // increment memory offset by 32
-					  << eth::Instruction::SWAP1 << u256(32) << eth::Instruction::ADD
-					  // check for loop condition
-					  << eth::Instruction::DUP1 << eth::Instruction::DUP4 << eth::Instruction::GT;
+			m_context << loopStart;
+			// load and store
+			m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
+			m_context << eth::Instruction::DUP2 << eth::Instruction::MSTORE;
+			// increment storage_data_offset by 1
+			m_context << eth::Instruction::SWAP1 << u256(1) << eth::Instruction::ADD;
+			// increment memory offset by 32
+			m_context << eth::Instruction::SWAP1 << u256(32) << eth::Instruction::ADD;
+			// check for loop condition
+			m_context << eth::Instruction::DUP1 << eth::Instruction::DUP4 << eth::Instruction::GT;
 			m_context.appendConditionalJumpTo(loopStart);
+			// stack here: memory_end_offset storage_data_offset memory_offset
+			if (_padToWordBoundaries)
+			{
+				// memory_end_offset - start is the actual length (we want to compute the ceil of).
+				// memory_offset - start is its next multiple of 32, but it might be off by 32.
+				// so we compute: memory_end_offset += (memory_offset - memory_end_offest) & 31
+				m_context << eth::Instruction::DUP3 << eth::Instruction::SWAP1 << eth::Instruction::SUB;
+				m_context << u256(31) << eth::Instruction::AND;
+				m_context << eth::Instruction::DUP3 << eth::Instruction::ADD;
+				m_context << eth::Instruction::SWAP2;
+			}
 			m_context << loopEnd << eth::Instruction::POP << eth::Instruction::POP;
 		}
 	}
@@ -159,6 +237,290 @@ void CompilerUtils::storeInMemoryDynamic(Type const& _type, bool _padToWordBound
 	}
 }
 
+void CompilerUtils::encodeToMemory(
+	TypePointers const& _givenTypes,
+	TypePointers const& _targetTypes,
+	bool _padToWordBoundaries,
+	bool _copyDynamicDataInPlace
+)
+{
+	// stack: <v1> <v2> ... <vn> <mem>
+	TypePointers targetTypes = _targetTypes.empty() ? _givenTypes : _targetTypes;
+	solAssert(targetTypes.size() == _givenTypes.size(), "");
+	for (TypePointer& t: targetTypes)
+		t = t->mobileType()->externalType();
+
+	// Stack during operation:
+	// <v1> <v2> ... <vn> <mem_start> <dyn_head_1> ... <dyn_head_r> <end_of_mem>
+	// The values dyn_head_i are added during the first loop and they point to the head part
+	// of the ith dynamic parameter, which is filled once the dynamic parts are processed.
+
+	// store memory start pointer
+	m_context << eth::Instruction::DUP1;
+
+	unsigned argSize = CompilerUtils::getSizeOnStack(_givenTypes);
+	unsigned stackPos = 0; // advances through the argument values
+	unsigned dynPointers = 0; // number of dynamic head pointers on the stack
+	for (size_t i = 0; i < _givenTypes.size(); ++i)
+	{
+		TypePointer targetType = targetTypes[i];
+		solAssert(!!targetType, "Externalable type expected.");
+		if (targetType->isDynamicallySized() && !_copyDynamicDataInPlace)
+		{
+			// leave end_of_mem as dyn head pointer
+			m_context << eth::Instruction::DUP1 << u256(32) << eth::Instruction::ADD;
+			dynPointers++;
+		}
+		else
+		{
+			copyToStackTop(argSize - stackPos + dynPointers + 2, _givenTypes[i]->getSizeOnStack());
+			if (targetType->isValueType())
+				convertType(*_givenTypes[i], *targetType, true);
+			solAssert(!!targetType, "Externalable type expected.");
+			storeInMemoryDynamic(*targetType, _padToWordBoundaries);
+		}
+		stackPos += _givenTypes[i]->getSizeOnStack();
+	}
+
+	// now copy the dynamic part
+	// Stack: <v1> <v2> ... <vn> <mem_start> <dyn_head_1> ... <dyn_head_r> <end_of_mem>
+	stackPos = 0;
+	unsigned thisDynPointer = 0;
+	for (size_t i = 0; i < _givenTypes.size(); ++i)
+	{
+		TypePointer targetType = targetTypes[i];
+		solAssert(!!targetType, "Externalable type expected.");
+		if (targetType->isDynamicallySized() && !_copyDynamicDataInPlace)
+		{
+			solAssert(_givenTypes[i]->getCategory() == Type::Category::Array, "Unknown dynamic type.");
+			auto const& arrayType = dynamic_cast<ArrayType const&>(*_givenTypes[i]);
+			// copy tail pointer (=mem_end - mem_start) to memory
+			m_context << eth::dupInstruction(2 + dynPointers) << eth::Instruction::DUP2;
+			m_context << eth::Instruction::SUB;
+			m_context << eth::dupInstruction(2 + dynPointers - thisDynPointer);
+			m_context << eth::Instruction::MSTORE;
+			// now copy the array
+			copyToStackTop(argSize - stackPos + dynPointers + 2, arrayType.getSizeOnStack());
+			// stack: ... <end_of_mem> <value...>
+			// copy length to memory
+			m_context << eth::dupInstruction(1 + arrayType.getSizeOnStack());
+			if (arrayType.location() == ReferenceType::Location::CallData)
+				m_context << eth::Instruction::DUP2; // length is on stack
+			else if (arrayType.location() == ReferenceType::Location::Storage)
+				m_context << eth::Instruction::DUP3 << eth::Instruction::SLOAD;
+			else
+			{
+				solAssert(arrayType.location() == ReferenceType::Location::Memory, "");
+				m_context << eth::Instruction::DUP2 << eth::Instruction::MLOAD;
+			}
+			// stack: ... <end_of_mem> <value...> <end_of_mem'> <length>
+			storeInMemoryDynamic(IntegerType(256), true);
+			// stack: ... <end_of_mem> <value...> <end_of_mem''>
+			// copy the new memory pointer
+			m_context << eth::swapInstruction(arrayType.getSizeOnStack() + 1) << eth::Instruction::POP;
+			// stack: ... <end_of_mem''> <value...>
+			// copy data part
+			storeInMemoryDynamic(arrayType, true);
+			// stack: ... <end_of_mem'''>
+
+			thisDynPointer++;
+		}
+		stackPos += _givenTypes[i]->getSizeOnStack();
+	}
+
+	// remove unneeded stack elements (and retain memory pointer)
+	m_context << eth::swapInstruction(argSize + dynPointers + 1);
+	popStackSlots(argSize + dynPointers + 1);
+}
+
+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
+	// previous operations.
+	// @todo: store in the AST whether the operand might have "dirty" higher order bits
+
+	if (_typeOnStack == _targetType && !_cleanupNeeded)
+		return;
+	Type::Category stackTypeCategory = _typeOnStack.getCategory();
+	Type::Category targetTypeCategory = _targetType.getCategory();
+
+	switch (stackTypeCategory)
+	{
+	case Type::Category::FixedBytes:
+	{
+		FixedBytesType const& typeOnStack = dynamic_cast<FixedBytesType const&>(_typeOnStack);
+		if (targetTypeCategory == Type::Category::Integer)
+		{
+			// conversion from bytes to integer. no need to clean the high bit
+			// only to shift right because of opposite alignment
+			IntegerType const& targetIntegerType = dynamic_cast<IntegerType const&>(_targetType);
+			m_context << (u256(1) << (256 - typeOnStack.getNumBytes() * 8)) << eth::Instruction::SWAP1 << eth::Instruction::DIV;
+			if (targetIntegerType.getNumBits() < typeOnStack.getNumBytes() * 8)
+				convertType(IntegerType(typeOnStack.getNumBytes() * 8), _targetType, _cleanupNeeded);
+		}
+		else
+		{
+			// clear lower-order bytes for conversion to shorter bytes - we always clean
+			solAssert(targetTypeCategory == Type::Category::FixedBytes, "Invalid type conversion requested.");
+			FixedBytesType const& targetType = dynamic_cast<FixedBytesType const&>(_targetType);
+			if (targetType.getNumBytes() < typeOnStack.getNumBytes())
+			{
+				if (targetType.getNumBytes() == 0)
+					m_context << eth::Instruction::DUP1 << eth::Instruction::XOR;
+				else
+				{
+					m_context << (u256(1) << (256 - targetType.getNumBytes() * 8));
+					m_context << eth::Instruction::DUP1 << eth::Instruction::SWAP2;
+					m_context << eth::Instruction::DIV << eth::Instruction::MUL;
+				}
+			}
+		}
+	}
+		break;
+	case Type::Category::Enum:
+		solAssert(targetTypeCategory == Type::Category::Integer || targetTypeCategory == Type::Category::Enum, "");
+		break;
+	case Type::Category::Integer:
+	case Type::Category::Contract:
+	case Type::Category::IntegerConstant:
+		if (targetTypeCategory == Type::Category::FixedBytes)
+		{
+			solAssert(stackTypeCategory == Type::Category::Integer || stackTypeCategory == Type::Category::IntegerConstant,
+				"Invalid conversion to FixedBytesType requested.");
+			// conversion from bytes to string. no need to clean the high bit
+			// only to shift left because of opposite alignment
+			FixedBytesType const& targetBytesType = dynamic_cast<FixedBytesType const&>(_targetType);
+			if (auto typeOnStack = dynamic_cast<IntegerType const*>(&_typeOnStack))
+				if (targetBytesType.getNumBytes() * 8 > typeOnStack->getNumBits())
+					cleanHigherOrderBits(*typeOnStack);
+			m_context << (u256(1) << (256 - targetBytesType.getNumBytes() * 8)) << eth::Instruction::MUL;
+		}
+		else if (targetTypeCategory == Type::Category::Enum)
+			// just clean
+			convertType(_typeOnStack, *_typeOnStack.mobileType(), true);
+		else
+		{
+			solAssert(targetTypeCategory == Type::Category::Integer || targetTypeCategory == Type::Category::Contract, "");
+			IntegerType addressType(0, IntegerType::Modifier::Address);
+			IntegerType const& targetType = targetTypeCategory == Type::Category::Integer
+				? dynamic_cast<IntegerType const&>(_targetType) : addressType;
+			if (stackTypeCategory == Type::Category::IntegerConstant)
+			{
+				IntegerConstantType const& constType = dynamic_cast<IntegerConstantType const&>(_typeOnStack);
+				// We know that the stack is clean, we only have to clean for a narrowing conversion
+				// where cleanup is forced.
+				if (targetType.getNumBits() < constType.getIntegerType()->getNumBits() && _cleanupNeeded)
+					cleanHigherOrderBits(targetType);
+			}
+			else
+			{
+				IntegerType const& typeOnStack = stackTypeCategory == Type::Category::Integer
+					? dynamic_cast<IntegerType const&>(_typeOnStack) : addressType;
+				// Widening: clean up according to source type width
+				// Non-widening and force: clean up according to target type bits
+				if (targetType.getNumBits() > typeOnStack.getNumBits())
+					cleanHigherOrderBits(typeOnStack);
+				else if (_cleanupNeeded)
+					cleanHigherOrderBits(targetType);
+			}
+		}
+		break;
+	case Type::Category::Array:
+	{
+		solAssert(targetTypeCategory == stackTypeCategory, "");
+		ArrayType const& typeOnStack = dynamic_cast<ArrayType const&>(_typeOnStack);
+		ArrayType const& targetType = dynamic_cast<ArrayType const&>(_targetType);
+		switch (targetType.location())
+		{
+		case ReferenceType::Location::Storage:
+			// Other cases are done explicitly in LValue::storeValue, and only possible by assignment.
+			solAssert(
+				targetType.isPointer() &&
+				typeOnStack.location() == ReferenceType::Location::Storage,
+				"Invalid conversion to storage type."
+			);
+			break;
+		case ReferenceType::Location::Memory:
+		{
+			// Copy the array to a free position in memory, unless it is already in memory.
+			if (typeOnStack.location() != ReferenceType::Location::Memory)
+			{
+				// stack: <source ref> (variably sized)
+				unsigned stackSize = typeOnStack.getSizeOnStack();
+				fetchFreeMemoryPointer();
+				moveIntoStack(stackSize);
+				// stack: <mem start> <source ref> (variably sized)
+				if (targetType.isDynamicallySized())
+				{
+					bool fromStorage = (typeOnStack.location() == ReferenceType::Location::Storage);
+					// store length
+					if (fromStorage)
+					{
+						stackSize--;
+						// remove storage offset, as requested by ArrayUtils::retrieveLength
+						m_context << eth::Instruction::POP;
+					}
+					ArrayUtils(m_context).retrieveLength(typeOnStack);
+					// Stack: <mem start> <source ref> <length>
+					m_context << eth::dupInstruction(2 + stackSize) << eth::Instruction::MSTORE;
+					m_context << eth::dupInstruction(1 + stackSize) << u256(0x20);
+					m_context << eth::Instruction::ADD;
+					moveIntoStack(stackSize);
+					if (fromStorage)
+					{
+						m_context << u256(0);
+						stackSize++;
+					}
+				}
+				else
+				{
+					m_context << eth::dupInstruction(1 + stackSize);
+					moveIntoStack(stackSize);
+				}
+				// Stack: <mem start> <mem data start> <value>
+				// Store data part.
+				storeInMemoryDynamic(typeOnStack);
+				// Stack <mem start> <mem end>
+				storeFreeMemoryPointer();
+			}
+			else if (typeOnStack.location() == ReferenceType::Location::CallData)
+			{
+				// Stack: <offset> <length>
+				//@todo
+				solAssert(false, "Not yet implemented.");
+			}
+			// nothing to do for memory to memory
+			break;
+		}
+		default:
+			solAssert(false, "Invalid type conversion requested.");
+		}
+		break;
+	}
+	case Type::Category::Struct:
+	{
+		//@todo we can probably use some of the code for arrays here.
+		solAssert(targetTypeCategory == stackTypeCategory, "");
+		auto& targetType = dynamic_cast<StructType const&>(_targetType);
+		auto& stackType = dynamic_cast<StructType const&>(_typeOnStack);
+		solAssert(
+			targetType.location() == ReferenceType::Location::Storage &&
+				stackType.location() == ReferenceType::Location::Storage,
+			"Non-storage structs not yet implemented."
+		);
+		solAssert(
+			targetType.isPointer(),
+			"Type conversion to non-pointer struct requested."
+		);
+		break;
+	}
+	default:
+		// All other types should not be convertible to non-equal types.
+		solAssert(_typeOnStack == _targetType, "Invalid type conversion requested.");
+		break;
+	}
+}
+
 void CompilerUtils::moveToStackVariable(VariableDeclaration const& _variable)
 {
 	unsigned const stackPosition = m_context.baseToCurrentStackOffset(m_context.getBaseStackOffsetOfVariable(_variable));
@@ -189,6 +551,13 @@ void CompilerUtils::moveToStackTop(unsigned _stackDepth)
 		m_context << eth::swapInstruction(1 + i);
 }
 
+void CompilerUtils::moveIntoStack(unsigned _stackDepth)
+{
+	solAssert(_stackDepth <= 16, "Stack too deep, try removing local variables.");
+	for (unsigned i = _stackDepth; i > 0; --i)
+		m_context << eth::swapInstruction(i);
+}
+
 void CompilerUtils::popStackElement(Type const& _type)
 {
 	popStackSlots(_type.getSizeOnStack());
@@ -238,6 +607,16 @@ unsigned CompilerUtils::loadFromMemoryHelper(Type const& _type, bool _fromCallda
 	return numBytes;
 }
 
+void CompilerUtils::cleanHigherOrderBits(IntegerType const& _typeOnStack)
+{
+	if (_typeOnStack.getNumBits() == 256)
+		return;
+	else if (_typeOnStack.isSigned())
+		m_context << u256(_typeOnStack.getNumBits() / 8 - 1) << eth::Instruction::SIGNEXTEND;
+	else
+		m_context << ((u256(1) << _typeOnStack.getNumBits()) - 1) << eth::Instruction::AND;
+}
+
 unsigned CompilerUtils::prepareMemoryStore(Type const& _type, bool _padToWordBoundaries) const
 {
 	unsigned numBytes = _type.getCalldataEncodedSize(_padToWordBoundaries);

libsolidity/CompilerUtils.h

@@ -81,6 +81,30 @@ public:
 	/// Stack post: (memory_offset+length)
 	void storeInMemoryDynamic(Type const& _type, bool _padToWordBoundaries = true);
 
+	/// Copies values (of types @a _givenTypes) given on the stack to a location in memory given
+	/// at the stack top, encoding them according to the ABI as the given types @a _targetTypes.
+	/// Removes the values from the stack and leaves the updated memory pointer.
+	/// Stack pre: <v1> <v2> ... <vn> <memptr>
+	/// Stack post: <memptr_updated>
+	/// Does not touch the memory-free pointer.
+	/// @param _padToWordBoundaries if false, all values are concatenated without padding.
+	/// @param _copyDynamicDataInPlace if true, dynamic types is stored (without length)
+	/// together with fixed-length data.
+	/// @note the locations of target reference types are ignored, because it will always be
+	/// memory.
+	void encodeToMemory(
+		TypePointers const& _givenTypes = {},
+		TypePointers const& _targetTypes = {},
+		bool _padToWordBoundaries = true,
+		bool _copyDynamicDataInPlace = false
+	);
+
+	/// Appends code for an implicit or explicit type conversion. For now this comprises only erasing
+	/// higher-order bits (@see appendHighBitCleanup) when widening integer.
+	/// If @a _cleanupNeeded, high order bits cleanup is also done if no type conversion would be
+	/// necessary.
+	void convertType(Type const& _typeOnStack, Type const& _targetType, bool _cleanupNeeded = false);
+
 	/// Moves the value that is at the top of the stack to a stack variable.
 	void moveToStackVariable(VariableDeclaration const& _variable);
 	/// Copies an item that occupies @a _itemSize stack slots from a stack depth of @a _stackDepth
@@ -88,6 +112,8 @@ public:
 	void copyToStackTop(unsigned _stackDepth, unsigned _itemSize);
 	/// Moves a single stack element (with _stackDepth items on top of it) to the top of the stack.
 	void moveToStackTop(unsigned _stackDepth);
+	/// Moves a single stack element past @a _stackDepth other stack elements
+	void moveIntoStack(unsigned _stackDepth);
 	/// Removes the current value from the top of the stack.
 	void popStackElement(Type const& _type);
 	/// Removes element from the top of the stack _amount times.
@@ -110,6 +136,12 @@ public:
 	static const size_t freeMemoryPointer;
 
 private:
+	/// Address of the precompiled identity contract.
+	static const unsigned identityContractAddress;
+
+	//// Appends code that cleans higher-order bits for integer types.
+	void cleanHigherOrderBits(IntegerType const& _typeOnStack);
+
 	/// Prepares the given type for storing in memory by shifting it if necessary.
 	unsigned prepareMemoryStore(Type const& _type, bool _padToWordBoundaries) const;
 	/// Loads type from memory assuming memory offset is on stack top.

libsolidity/ExpressionCompiler.cpp

@@ -51,7 +51,7 @@ void ExpressionCompiler::appendStateVariableInitialization(VariableDeclaration c
 	solAssert(!!_varDecl.getValue()->getType(), "Type information not available.");
 	CompilerContext::LocationSetter locationSetter(m_context, _varDecl);
 	_varDecl.getValue()->accept(*this);
-	appendTypeConversion(*_varDecl.getValue()->getType(), *_varDecl.getType(), true);
+	utils().convertType(*_varDecl.getValue()->getType(), *_varDecl.getType(), true);
 
 	StorageItem(m_context, _varDecl).storeValue(*_varDecl.getType(), _varDecl.getLocation(), true);
 }
@@ -77,10 +77,10 @@ void ExpressionCompiler::appendStateVariableAccessor(VariableDeclaration const&
 			// pop offset
 			m_context << eth::Instruction::POP;
 			// move storage offset to memory.
-			CompilerUtils(m_context).storeInMemory(32);
+			utils().storeInMemory(32);
 			// move key to memory.
-			CompilerUtils(m_context).copyToStackTop(paramTypes.size() - i, 1);
-			CompilerUtils(m_context).storeInMemory(0);
+			utils().copyToStackTop(paramTypes.size() - i, 1);
+			utils().storeInMemory(0);
 			m_context << u256(64) << u256(0) << eth::Instruction::SHA3;
 			// push offset
 			m_context << u256(0);
@@ -90,7 +90,7 @@ void ExpressionCompiler::appendStateVariableAccessor(VariableDeclaration const&
 		{
 			// pop offset
 			m_context << eth::Instruction::POP;
-			CompilerUtils(m_context).copyToStackTop(paramTypes.size() - i + 1, 1);
+			utils().copyToStackTop(paramTypes.size() - i + 1, 1);
 			ArrayUtils(m_context).accessIndex(*arrayType);
 			returnType = arrayType->getBaseType();
 		}
@@ -105,7 +105,7 @@ void ExpressionCompiler::appendStateVariableAccessor(VariableDeclaration const&
 		m_context << eth::swapInstruction(paramTypes.size());
 		m_context << eth::Instruction::POP;
 		m_context << eth::swapInstruction(paramTypes.size());
-		CompilerUtils(m_context).popStackSlots(paramTypes.size() - 1);
+		utils().popStackSlots(paramTypes.size() - 1);
 	}
 	unsigned retSizeOnStack = 0;
 	solAssert(accessorType.getReturnParameterTypes().size() >= 1, "");
@@ -142,128 +142,14 @@ void ExpressionCompiler::appendStateVariableAccessor(VariableDeclaration const&
 	m_context.appendJump(eth::AssemblyItem::JumpType::OutOfFunction);
 }
 
-void ExpressionCompiler::appendTypeConversion(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
-	// previous operations.
-	// @todo: store in the AST whether the operand might have "dirty" higher order bits
-
-	if (_typeOnStack == _targetType && !_cleanupNeeded)
-		return;
-	Type::Category stackTypeCategory = _typeOnStack.getCategory();
-	Type::Category targetTypeCategory = _targetType.getCategory();
-
-	switch (stackTypeCategory)
-	{
-	case Type::Category::FixedBytes:
-	{
-		FixedBytesType const& typeOnStack = dynamic_cast<FixedBytesType const&>(_typeOnStack);
-		if (targetTypeCategory == Type::Category::Integer)
-		{
-			// conversion from bytes to integer. no need to clean the high bit
-			// only to shift right because of opposite alignment
-			IntegerType const& targetIntegerType = dynamic_cast<IntegerType const&>(_targetType);
-			m_context << (u256(1) << (256 - typeOnStack.getNumBytes() * 8)) << eth::Instruction::SWAP1 << eth::Instruction::DIV;
-			if (targetIntegerType.getNumBits() < typeOnStack.getNumBytes() * 8)
-				appendTypeConversion(IntegerType(typeOnStack.getNumBytes() * 8), _targetType, _cleanupNeeded); 
-		}
-		else
-		{
-			// clear lower-order bytes for conversion to shorter bytes - we always clean
-			solAssert(targetTypeCategory == Type::Category::FixedBytes, "Invalid type conversion requested.");
-			FixedBytesType const& targetType = dynamic_cast<FixedBytesType const&>(_targetType);
-			if (targetType.getNumBytes() < typeOnStack.getNumBytes())
-			{
-				if (targetType.getNumBytes() == 0)
-					m_context << eth::Instruction::DUP1 << eth::Instruction::XOR;
-				else
-					m_context << (u256(1) << (256 - targetType.getNumBytes() * 8))
-							  << eth::Instruction::DUP1 << eth::Instruction::SWAP2
-							  << eth::Instruction::DIV << eth::Instruction::MUL;
-			}
-		}
-	}
-		break;
-	case Type::Category::Enum:
-		solAssert(targetTypeCategory == Type::Category::Integer || targetTypeCategory == Type::Category::Enum, "");
-		break;
-	case Type::Category::Integer:
-	case Type::Category::Contract:
-	case Type::Category::IntegerConstant:
-		if (targetTypeCategory == Type::Category::FixedBytes)
-		{
-			solAssert(stackTypeCategory == Type::Category::Integer || stackTypeCategory == Type::Category::IntegerConstant,
-				"Invalid conversion to FixedBytesType requested.");
-			// conversion from bytes to string. no need to clean the high bit
-			// only to shift left because of opposite alignment
-			FixedBytesType const& targetBytesType = dynamic_cast<FixedBytesType const&>(_targetType);
-			if (auto typeOnStack = dynamic_cast<IntegerType const*>(&_typeOnStack))
-				if (targetBytesType.getNumBytes() * 8 > typeOnStack->getNumBits())
-					appendHighBitsCleanup(*typeOnStack);
-			m_context << (u256(1) << (256 - targetBytesType.getNumBytes() * 8)) << eth::Instruction::MUL;
-		}
-		else if (targetTypeCategory == Type::Category::Enum)
-			// just clean
-			appendTypeConversion(_typeOnStack, *_typeOnStack.mobileType(), true);
-		else
-		{
-			solAssert(targetTypeCategory == Type::Category::Integer || targetTypeCategory == Type::Category::Contract, "");
-			IntegerType addressType(0, IntegerType::Modifier::Address);
-			IntegerType const& targetType = targetTypeCategory == Type::Category::Integer
-				? dynamic_cast<IntegerType const&>(_targetType) : addressType;
-			if (stackTypeCategory == Type::Category::IntegerConstant)
-			{
-				IntegerConstantType const& constType = dynamic_cast<IntegerConstantType const&>(_typeOnStack);
-				// We know that the stack is clean, we only have to clean for a narrowing conversion
-				// where cleanup is forced.
-				if (targetType.getNumBits() < constType.getIntegerType()->getNumBits() && _cleanupNeeded)
-					appendHighBitsCleanup(targetType);
-			}
-			else
-			{
-				IntegerType const& typeOnStack = stackTypeCategory == Type::Category::Integer
-					? dynamic_cast<IntegerType const&>(_typeOnStack) : addressType;
-				// Widening: clean up according to source type width
-				// Non-widening and force: clean up according to target type bits
-				if (targetType.getNumBits() > typeOnStack.getNumBits())
-					appendHighBitsCleanup(typeOnStack);
-				else if (_cleanupNeeded)
-					appendHighBitsCleanup(targetType);
-			}
-		}
-		break;
-	case Type::Category::Array:
-		//@TODO
-		break;
-	case Type::Category::Struct:
-	{
-		solAssert(targetTypeCategory == stackTypeCategory, "");
-		auto& targetType = dynamic_cast<StructType const&>(_targetType);
-		auto& stackType = dynamic_cast<StructType const&>(_typeOnStack);
-		solAssert(
-			targetType.location() == ReferenceType::Location::Storage &&
-				stackType.location() == ReferenceType::Location::Storage,
-			"Non-storage structs not yet implemented."
-		);
-		solAssert(
-			targetType.isPointer(),
-			"Type conversion to non-pointer struct requested."
-		);
-		break;
-	}
-	default:
-		// All other types should not be convertible to non-equal types.
-		solAssert(_typeOnStack == _targetType, "Invalid type conversion requested.");
-		break;
-	}
-}
-
 bool ExpressionCompiler::visit(Assignment const& _assignment)
 {
 	CompilerContext::LocationSetter locationSetter(m_context, _assignment);
 	_assignment.getRightHandSide().accept(*this);
 	if (_assignment.getType()->isValueType())
-		appendTypeConversion(*_assignment.getRightHandSide().getType(), *_assignment.getType());
+		utils().convertType(*_assignment.getRightHandSide().getType(), *_assignment.getType());
+	// We need this conversion mostly in the case of compound assignments. For non-value types
+	// the conversion is done in LValue::storeValue.
 	_assignment.getLeftHandSide().accept(*this);
 	solAssert(!!m_currentLValue, "LValue not retrieved.");
 
@@ -275,8 +161,8 @@ bool ExpressionCompiler::visit(Assignment const& _assignment)
 		unsigned itemSize = _assignment.getType()->getSizeOnStack();
 		if (lvalueSize > 0)
 		{
-			CompilerUtils(m_context).copyToStackTop(lvalueSize + itemSize, itemSize);
-			CompilerUtils(m_context).copyToStackTop(itemSize + lvalueSize, lvalueSize);
+			utils().copyToStackTop(lvalueSize + itemSize, itemSize);
+			utils().copyToStackTop(itemSize + lvalueSize, lvalueSize);
 			// value lvalue_ref value lvalue_ref
 		}
 		m_currentLValue->retrieveValue(_assignment.getLocation(), true);
@@ -391,16 +277,16 @@ bool ExpressionCompiler::visit(BinaryOperation const& _binaryOperation)
 		if (swap)
 		{
 			leftExpression.accept(*this);
-			appendTypeConversion(*leftExpression.getType(), commonType, cleanupNeeded);
+			utils().convertType(*leftExpression.getType(), commonType, cleanupNeeded);
 			rightExpression.accept(*this);
-			appendTypeConversion(*rightExpression.getType(), commonType, cleanupNeeded);
+			utils().convertType(*rightExpression.getType(), commonType, cleanupNeeded);
 		}
 		else
 		{
 			rightExpression.accept(*this);
-			appendTypeConversion(*rightExpression.getType(), commonType, cleanupNeeded);
+			utils().convertType(*rightExpression.getType(), commonType, cleanupNeeded);
 			leftExpression.accept(*this);
-			appendTypeConversion(*leftExpression.getType(), commonType, cleanupNeeded);
+			utils().convertType(*leftExpression.getType(), commonType, cleanupNeeded);
 		}
 		if (Token::isCompareOp(c_op))
 			appendCompareOperatorCode(c_op, commonType);
@@ -423,7 +309,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 		solAssert(_functionCall.getNames().empty(), "");
 		Expression const& firstArgument = *_functionCall.getArguments().front();
 		firstArgument.accept(*this);
-		appendTypeConversion(*firstArgument.getType(), *_functionCall.getType());
+		utils().convertType(*firstArgument.getType(), *_functionCall.getType());
 	}
 	else
 	{
@@ -461,7 +347,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			for (unsigned i = 0; i < arguments.size(); ++i)
 			{
 				arguments[i]->accept(*this);
-				appendTypeConversion(*arguments[i]->getType(), *function.getParameterTypes()[i]);
+				utils().convertType(*arguments[i]->getType(), *function.getParameterTypes()[i]);
 			}
 			_functionCall.getExpression().accept(*this);
 
@@ -475,7 +361,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			// @todo for now, the return value of a function is its first return value, so remove
 			// all others
 			for (unsigned i = 1; i < function.getReturnParameterTypes().size(); ++i)
-				CompilerUtils(m_context).popStackElement(*function.getReturnParameterTypes()[i]);
+				utils().popStackElement(*function.getReturnParameterTypes()[i]);
 			break;
 		}
 		case Location::External:
@@ -500,7 +386,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 							*function.getReturnParameterTypes().front()).getContractDefinition();
 			// copy the contract's code into memory
 			bytes const& bytecode = m_context.getCompiledContract(contract);
-			CompilerUtils(m_context).fetchFreeMemoryPointer();
+			utils().fetchFreeMemoryPointer();
 			m_context << u256(bytecode.size()) << eth::Instruction::DUP1;
 			//@todo could be done by actually appending the Assembly, but then we probably need to compile
 			// multiple times. Will revisit once external fuctions are inlined.
@@ -508,10 +394,10 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			m_context << eth::Instruction::DUP4 << eth::Instruction::CODECOPY;
 
 			m_context << eth::Instruction::ADD;
-			encodeToMemory(argumentTypes, function.getParameterTypes());
+			utils().encodeToMemory(argumentTypes, function.getParameterTypes());
 			// now on stack: memory_end_ptr
 			// need: size, offset, endowment
-			CompilerUtils(m_context).toSizeAfterFreeMemoryPointer();
+			utils().toSizeAfterFreeMemoryPointer();
 			if (function.valueSet())
 				m_context << eth::dupInstruction(3);
 			else
@@ -527,7 +413,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			_functionCall.getExpression().accept(*this);
 
 			arguments.front()->accept(*this);
-			appendTypeConversion(*arguments.front()->getType(), IntegerType(256), true);
+			utils().convertType(*arguments.front()->getType(), IntegerType(256), true);
 			// Note that function is not the original function, but the ".gas" function.
 			// Its values of gasSet and valueSet is equal to the original function's though.
 			unsigned stackDepth = (function.gasSet() ? 1 : 0) + (function.valueSet() ? 1 : 0);
@@ -550,8 +436,10 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			_functionCall.getExpression().accept(*this);
 			m_context << u256(0); // do not send gas (there still is the stipend)
 			arguments.front()->accept(*this);
-			appendTypeConversion(*arguments.front()->getType(),
-								 *function.getParameterTypes().front(), true);
+			utils().convertType(
+				*arguments.front()->getType(),
+				*function.getParameterTypes().front(), true
+			);
 			appendExternalFunctionCall(
 				FunctionType(
 					TypePointers{},
@@ -568,7 +456,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			break;
 		case Location::Suicide:
 			arguments.front()->accept(*this);
-			appendTypeConversion(*arguments.front()->getType(), *function.getParameterTypes().front(), true);
+			utils().convertType(*arguments.front()->getType(), *function.getParameterTypes().front(), true);
 			m_context << eth::Instruction::SUICIDE;
 			break;
 		case Location::SHA3:
@@ -579,9 +467,9 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 				arg->accept(*this);
 				argumentTypes.push_back(arg->getType());
 			}
-			CompilerUtils(m_context).fetchFreeMemoryPointer();
-			encodeToMemory(argumentTypes, TypePointers(), function.padArguments(), true);
-			CompilerUtils(m_context).toSizeAfterFreeMemoryPointer();
+			utils().fetchFreeMemoryPointer();
+			utils().encodeToMemory(argumentTypes, TypePointers(), function.padArguments(), true);
+			utils().toSizeAfterFreeMemoryPointer();
 			m_context << eth::Instruction::SHA3;
 			break;
 		}
@@ -595,16 +483,16 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			for (unsigned arg = logNumber; arg > 0; --arg)
 			{
 				arguments[arg]->accept(*this);
-				appendTypeConversion(*arguments[arg]->getType(), *function.getParameterTypes()[arg], true);
+				utils().convertType(*arguments[arg]->getType(), *function.getParameterTypes()[arg], true);
 			}
 			arguments.front()->accept(*this);
-			CompilerUtils(m_context).fetchFreeMemoryPointer();
-			encodeToMemory(
+			utils().fetchFreeMemoryPointer();
+			utils().encodeToMemory(
 				{arguments.front()->getType()},
 				{function.getParameterTypes().front()},
 				false,
 				true);
-			CompilerUtils(m_context).toSizeAfterFreeMemoryPointer();
+			utils().toSizeAfterFreeMemoryPointer();
 			m_context << eth::logInstruction(logNumber);
 			break;
 		}
@@ -619,7 +507,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 				{
 					++numIndexed;
 					arguments[arg - 1]->accept(*this);
-					appendTypeConversion(
+					utils().convertType(
 						*arguments[arg - 1]->getType(),
 						*function.getParameterTypes()[arg - 1],
 						true
@@ -642,17 +530,17 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 					nonIndexedArgTypes.push_back(arguments[arg]->getType());
 					nonIndexedParamTypes.push_back(function.getParameterTypes()[arg]);
 				}
-			CompilerUtils(m_context).fetchFreeMemoryPointer();
-			encodeToMemory(nonIndexedArgTypes, nonIndexedParamTypes);
+			utils().fetchFreeMemoryPointer();
+			utils().encodeToMemory(nonIndexedArgTypes, nonIndexedParamTypes);
 			// need: topic1 ... topicn memsize memstart
-			CompilerUtils(m_context).toSizeAfterFreeMemoryPointer();
+			utils().toSizeAfterFreeMemoryPointer();
 			m_context << eth::logInstruction(numIndexed);
 			break;
 		}
 		case Location::BlockHash:
 		{
 			arguments[0]->accept(*this);
-			appendTypeConversion(*arguments[0]->getType(), *function.getParameterTypes()[0], true);
+			utils().convertType(*arguments[0]->getType(), *function.getParameterTypes()[0], true);
 			m_context << eth::Instruction::BLOCKHASH;
 			break;
 		}
@@ -713,7 +601,7 @@ void ExpressionCompiler::endVisit(MemberAccess const& _memberAccess)
 					identifier = FunctionType(*function).externalIdentifier();
 				else
 					solAssert(false, "Contract member is neither variable nor function.");
-				appendTypeConversion(type, IntegerType(0, IntegerType::Modifier::Address), true);
+				utils().convertType(type, IntegerType(0, IntegerType::Modifier::Address), true);
 				m_context << identifier;
 			}
 			else
@@ -726,13 +614,19 @@ void ExpressionCompiler::endVisit(MemberAccess const& _memberAccess)
 	case Type::Category::Integer:
 		if (member == "balance")
 		{
-			appendTypeConversion(*_memberAccess.getExpression().getType(),
-								 IntegerType(0, IntegerType::Modifier::Address), true);
+			utils().convertType(
+				*_memberAccess.getExpression().getType(),
+				IntegerType(0, IntegerType::Modifier::Address),
+				true
+			);
 			m_context << eth::Instruction::BALANCE;
 		}
 		else if ((set<string>{"send", "call", "callcode"}).count(member))
-			appendTypeConversion(*_memberAccess.getExpression().getType(),
-								 IntegerType(0, IntegerType::Modifier::Address), true);
+			utils().convertType(
+				*_memberAccess.getExpression().getType(),
+				IntegerType(0, IntegerType::Modifier::Address),
+				true
+			);
 		else
 			BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Invalid member access to integer."));
 		break;
@@ -809,7 +703,7 @@ void ExpressionCompiler::endVisit(MemberAccess const& _memberAccess)
 		auto const& type = dynamic_cast<ArrayType const&>(*_memberAccess.getExpression().getType());
 		if (!type.isDynamicallySized())
 		{
-			CompilerUtils(m_context).popStackElement(type);
+			utils().popStackElement(type);
 			m_context << type.getLength();
 		}
 		else
@@ -850,7 +744,7 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 		appendExpressionCopyToMemory(keyType, *_indexAccess.getIndexExpression());
 		m_context << eth::Instruction::SWAP1;
 		solAssert(CompilerUtils::freeMemoryPointer >= 0x40, "");
-		appendTypeMoveToMemory(IntegerType(256));
+		utils().storeInMemoryDynamic(IntegerType(256));
 		m_context << u256(0) << eth::Instruction::SHA3;
 		m_context << u256(0);
 		setLValueToStorageItem(_indexAccess);
@@ -1071,16 +965,6 @@ void ExpressionCompiler::appendShiftOperatorCode(Token::Value _operator)
 	}
 }
 
-void ExpressionCompiler::appendHighBitsCleanup(IntegerType const& _typeOnStack)
-{
-	if (_typeOnStack.getNumBits() == 256)
-		return;
-	else if (_typeOnStack.isSigned())
-		m_context << u256(_typeOnStack.getNumBits() / 8 - 1) << eth::Instruction::SIGNEXTEND;
-	else
-		m_context << ((u256(1) << _typeOnStack.getNumBits()) - 1) << eth::Instruction::AND;
-}
-
 void ExpressionCompiler::appendExternalFunctionCall(
 	FunctionType const& _functionType,
 	vector<ASTPointer<Expression const>> const& _arguments
@@ -1127,7 +1011,7 @@ void ExpressionCompiler::appendExternalFunctionCall(
 		// If we have a BareCall or BareCallCode and the first type has exactly 4 bytes, use it as
 		// function identifier.
 		_arguments.front()->accept(*this);
-		appendTypeConversion(
+		utils().convertType(
 			*_arguments.front()->getType(),
 			IntegerType(8 * CompilerUtils::dataStartOffset),
 			true
@@ -1144,16 +1028,16 @@ void ExpressionCompiler::appendExternalFunctionCall(
 	}
 
 	// Copy function identifier to memory.
-	CompilerUtils(m_context).fetchFreeMemoryPointer();
+	utils().fetchFreeMemoryPointer();
 	if (!_functionType.isBareCall() || manualFunctionId)
 	{
 		m_context << eth::dupInstruction(2 + gasValueSize + CompilerUtils::getSizeOnStack(argumentTypes));
-		appendTypeMoveToMemory(IntegerType(8 * CompilerUtils::dataStartOffset), false);
+		utils().storeInMemoryDynamic(IntegerType(8 * CompilerUtils::dataStartOffset), false);
 	}
 	// If the function takes arbitrary parameters, copy dynamic length data in place.
 	// Move argumenst to memory, will not update the free memory pointer (but will update the memory
 	// pointer on the stack).
-	encodeToMemory(
+	utils().encodeToMemory(
 		argumentTypes,
 		_functionType.getParameterTypes(),
 		_functionType.padArguments(),
@@ -1171,7 +1055,7 @@ void ExpressionCompiler::appendExternalFunctionCall(
 	// Output data will replace input data.
 	// put on stack: <size of output> <memory pos of output> <size of input> <memory pos of input>
 	m_context << u256(retSize);
-	CompilerUtils(m_context).fetchFreeMemoryPointer();
+	utils().fetchFreeMemoryPointer();
 	m_context << eth::Instruction::DUP1 << eth::Instruction::DUP4 << eth::Instruction::SUB;
 	m_context << eth::Instruction::DUP2;
 
@@ -1212,7 +1096,7 @@ void ExpressionCompiler::appendExternalFunctionCall(
 		m_context.appendConditionalJumpTo(m_context.errorTag());
 	}
 
-	CompilerUtils(m_context).popStackSlots(remainsSize);
+	utils().popStackSlots(remainsSize);
 
 	if (returnSuccessCondition)
 	{
@@ -1221,130 +1105,28 @@ void ExpressionCompiler::appendExternalFunctionCall(
 	else if (funKind == FunctionKind::RIPEMD160)
 	{
 		// fix: built-in contract returns right-aligned data
-		CompilerUtils(m_context).fetchFreeMemoryPointer();
-		CompilerUtils(m_context).loadFromMemoryDynamic(IntegerType(160), false, true, false);
-		appendTypeConversion(IntegerType(160), FixedBytesType(20));
+		utils().fetchFreeMemoryPointer();
+		utils().loadFromMemoryDynamic(IntegerType(160), false, true, false);
+		utils().convertType(IntegerType(160), FixedBytesType(20));
 	}
 	else if (firstReturnType)
 	{
 		//@todo manually update free memory pointer if we accept returning memory-stored objects
-		CompilerUtils(m_context).fetchFreeMemoryPointer();
-		CompilerUtils(m_context).loadFromMemoryDynamic(*firstReturnType, false, true, false);
+		utils().fetchFreeMemoryPointer();
+		utils().loadFromMemoryDynamic(*firstReturnType, false, true, false);
 	}
 }
 
-void ExpressionCompiler::encodeToMemory(
-	TypePointers const& _givenTypes,
-	TypePointers const& _targetTypes,
-	bool _padToWordBoundaries,
-	bool _copyDynamicDataInPlace
-)
-{
-	// stack: <v1> <v2> ... <vn> <mem>
-	TypePointers targetTypes = _targetTypes.empty() ? _givenTypes : _targetTypes;
-	solAssert(targetTypes.size() == _givenTypes.size(), "");
-	for (TypePointer& t: targetTypes)
-		t = t->mobileType()->externalType();
-
-	// Stack during operation:
-	// <v1> <v2> ... <vn> <mem_start> <dyn_head_1> ... <dyn_head_r> <end_of_mem>
-	// The values dyn_head_i are added during the first loop and they point to the head part
-	// of the ith dynamic parameter, which is filled once the dynamic parts are processed.
-
-	// store memory start pointer
-	m_context << eth::Instruction::DUP1;
-
-	unsigned argSize = CompilerUtils::getSizeOnStack(_givenTypes);
-	unsigned stackPos = 0; // advances through the argument values
-	unsigned dynPointers = 0; // number of dynamic head pointers on the stack
-	for (size_t i = 0; i < _givenTypes.size(); ++i)
-	{
-		TypePointer targetType = targetTypes[i];
-		solAssert(!!targetType, "Externalable type expected.");
-		if (targetType->isDynamicallySized() && !_copyDynamicDataInPlace)
-		{
-			// leave end_of_mem as dyn head pointer
-			m_context << eth::Instruction::DUP1 << u256(32) << eth::Instruction::ADD;
-			dynPointers++;
-		}
-		else
-		{
-			CompilerUtils(m_context).copyToStackTop(
-				argSize - stackPos + dynPointers + 2,
-				_givenTypes[i]->getSizeOnStack()
-			);
-			if (targetType->isValueType())
-				appendTypeConversion(*_givenTypes[i], *targetType, true);
-			solAssert(!!targetType, "Externalable type expected.");
-			appendTypeMoveToMemory(*targetType, _padToWordBoundaries);
-		}
-		stackPos += _givenTypes[i]->getSizeOnStack();
-	}
-
-	// now copy the dynamic part
-	// Stack: <v1> <v2> ... <vn> <mem_start> <dyn_head_1> ... <dyn_head_r> <end_of_mem>
-	stackPos = 0;
-	unsigned thisDynPointer = 0;
-	for (size_t i = 0; i < _givenTypes.size(); ++i)
-	{
-		TypePointer targetType = targetTypes[i];
-		solAssert(!!targetType, "Externalable type expected.");
-		if (targetType->isDynamicallySized() && !_copyDynamicDataInPlace)
-		{
-			solAssert(_givenTypes[i]->getCategory() == Type::Category::Array, "Unknown dynamic type.");
-			auto const& arrayType = dynamic_cast<ArrayType const&>(*_givenTypes[i]);
-			// copy tail pointer (=mem_end - mem_start) to memory
-			m_context << eth::dupInstruction(2 + dynPointers) << eth::Instruction::DUP2;
-			m_context << eth::Instruction::SUB;
-			m_context << eth::dupInstruction(2 + dynPointers - thisDynPointer);
-			m_context << eth::Instruction::MSTORE;
-			// now copy the array
-			CompilerUtils(m_context).copyToStackTop(
-				argSize - stackPos + dynPointers + 2,
-				arrayType.getSizeOnStack()
-			);
-			// copy length to memory
-			m_context << eth::dupInstruction(1 + arrayType.getSizeOnStack());
-			if (arrayType.location() == ReferenceType::Location::CallData)
-				m_context << eth::Instruction::DUP2; // length is on stack
-			else if (arrayType.location() == ReferenceType::Location::Storage)
-				m_context << eth::Instruction::DUP3 << eth::Instruction::SLOAD;
-			else
-			{
-				solAssert(arrayType.location() == ReferenceType::Location::Memory, "");
-				m_context << eth::Instruction::DUP2 << eth::Instruction::MLOAD;
-			}
-			appendTypeMoveToMemory(IntegerType(256), true);
-			// copy the new memory pointer
-			m_context << eth::swapInstruction(arrayType.getSizeOnStack() + 1) << eth::Instruction::POP;
-			// copy data part
-			appendTypeMoveToMemory(arrayType, true);
-
-			thisDynPointer++;
-		}
-		stackPos += _givenTypes[i]->getSizeOnStack();
-	}
-
-	// remove unneeded stack elements (and retain memory pointer)
-	m_context << eth::swapInstruction(argSize + dynPointers + 1);
-	CompilerUtils(m_context).popStackSlots(argSize + dynPointers + 1);
-}
-
-void ExpressionCompiler::appendTypeMoveToMemory(Type const& _type, bool _padToWordBoundaries)
-{
-	CompilerUtils(m_context).storeInMemoryDynamic(_type, _padToWordBoundaries);
-}
-
 void ExpressionCompiler::appendExpressionCopyToMemory(Type const& _expectedType, Expression const& _expression)
 {
 	_expression.accept(*this);
 	if (_expectedType.isValueType())
 	{
-		appendTypeConversion(*_expression.getType(), _expectedType, true);
-		appendTypeMoveToMemory(_expectedType);
+		utils().convertType(*_expression.getType(), _expectedType, true);
+		utils().storeInMemoryDynamic(_expectedType);
 	}
 	else
-		appendTypeMoveToMemory(*_expression.getType()->mobileType());
+		utils().storeInMemoryDynamic(*_expression.getType()->mobileType());
 }
 
 void ExpressionCompiler::setLValueFromDeclaration(Declaration const& _declaration, Expression const& _expression)
@@ -1364,5 +1146,10 @@ void ExpressionCompiler::setLValueToStorageItem(Expression const& _expression)
 	setLValue<StorageItem>(_expression, *_expression.getType());
 }
 
+CompilerUtils ExpressionCompiler::utils()
+{
+	return CompilerUtils(m_context);
+}
+
 }
 }

libsolidity/ExpressionCompiler.h

@@ -26,9 +26,9 @@
 #include <boost/noncopyable.hpp>
 #include <libdevcore/Common.h>
 #include <libevmasm/SourceLocation.h>
-#include <libsolidity/Utils.h>
 #include <libsolidity/ASTVisitor.h>
 #include <libsolidity/LValue.h>
+#include <libsolidity/Utils.h>
 
 namespace dev {
 namespace eth
@@ -39,6 +39,7 @@ namespace solidity {
 
 // forward declarations
 class CompilerContext;
+class CompilerUtils;
 class Type;
 class IntegerType;
 class ArrayType;
@@ -66,12 +67,6 @@ public:
 	/// Appends code for a State Variable accessor function
 	void appendStateVariableAccessor(VariableDeclaration const& _varDecl);
 
-	/// Appends an implicit or explicit type conversion. For now this comprises only erasing
-	/// higher-order bits (@see appendHighBitCleanup) when widening integer.
-	/// If @a _cleanupNeeded, high order bits cleanup is also done if no type conversion would be
-	/// necessary.
-	void appendTypeConversion(Type const& _typeOnStack, Type const& _targetType, bool _cleanupNeeded = false);
-
 private:
 	virtual bool visit(Assignment const& _assignment) override;
 	virtual bool visit(UnaryOperation const& _unaryOperation) override;
@@ -94,33 +89,11 @@ private:
 	void appendShiftOperatorCode(Token::Value _operator);
 	/// @}
 
-	//// Appends code that cleans higher-order bits for integer types.
-	void appendHighBitsCleanup(IntegerType const& _typeOnStack);
-
 	/// Appends code to call a function of the given type with the given arguments.
 	void appendExternalFunctionCall(
 		FunctionType const& _functionType,
 		std::vector<ASTPointer<Expression const>> const& _arguments
 	);
-	/// Copies values (of types @a _givenTypes) given on the stack to a location in memory given
-	/// at the stack top, encoding them according to the ABI as the given types @a _targetTypes.
-	/// Removes the values from the stack and leaves the updated memory pointer.
-	/// Stack pre: <v1> <v2> ... <vn> <memptr>
-	/// Stack post: <memptr_updated>
-	/// Does not touch the memory-free pointer.
-	/// @param _padToWordBoundaries if false, all values are concatenated without padding.
-	/// @param _copyDynamicDataInPlace if true, dynamic types is stored (without length)
-	/// together with fixed-length data.
-	void encodeToMemory(
-		TypePointers const& _givenTypes = {},
-		TypePointers const& _targetTypes = {},
-		bool _padToWordBoundaries = true,
-		bool _copyDynamicDataInPlace = false
-	);
-	/// Appends code that moves a stack element of the given type to memory. The memory offset is
-	/// expected below the stack element and is updated by this call.
-	/// For arrays, this only copies the data part.
-	void appendTypeMoveToMemory(Type const& _type, bool _padToWordBoundaries = true);
 	/// Appends code that evaluates a single expression and moves the result to memory. The memory offset is
 	/// expected to be on the stack and is updated by this call.
 	void appendExpressionCopyToMemory(Type const& _expectedType, Expression const& _expression);
@@ -137,9 +110,13 @@ private:
 	template <class _LValueType, class... _Arguments>
 	void setLValue(Expression const& _expression, _Arguments const&... _arguments);
 
+	/// @returns the CompilerUtils object containing the current context.
+	CompilerUtils utils();
+
 	bool m_optimize;
 	CompilerContext& m_context;
 	std::unique_ptr<LValue> m_currentLValue;
+
 };
 
 template <class _LValueType, class... _Arguments>

test/libsolidity/Assembly.cpp

@@ -106,7 +106,7 @@ BOOST_AUTO_TEST_CASE(location_test)
 	AssemblyItems items = compileContract(sourceCode);
 	vector<SourceLocation> locations =
 		vector<SourceLocation>(17, SourceLocation(2, 75, n)) +
-		vector<SourceLocation>(14, SourceLocation(20, 72, n)) +
+		vector<SourceLocation>(26, SourceLocation(20, 72, n)) +
 		vector<SourceLocation>{SourceLocation(42, 51, n), SourceLocation(65, 67, n)} +
 		vector<SourceLocation>(4, SourceLocation(58, 67, n)) +
 		vector<SourceLocation>(3, SourceLocation(20, 72, n));

test/libsolidity/SolidityEndToEndTest.cpp

@@ -2420,7 +2420,7 @@ BOOST_AUTO_TEST_CASE(event_really_lots_of_data_from_storage)
 	callContractFunction("deposit()");
 	BOOST_REQUIRE_EQUAL(m_logs.size(), 1);
 	BOOST_CHECK_EQUAL(m_logs[0].address, m_contractAddress);
-	BOOST_CHECK(m_logs[0].data == encodeArgs(10, 0x60, 15, 3) + asBytes("ABC"));
+	BOOST_CHECK(m_logs[0].data == encodeArgs(10, 0x60, 15, 3, string("ABC")));
 	BOOST_REQUIRE_EQUAL(m_logs[0].topics.size(), 1);
 	BOOST_CHECK_EQUAL(m_logs[0].topics[0], dev::sha3(string("Deposit(uint256,bytes,uint256)")));
 }
@@ -4232,6 +4232,31 @@ BOOST_AUTO_TEST_CASE(reusing_memory)
 	BOOST_REQUIRE(callContractFunction("f(uint256)", 0x34) == encodeArgs(dev::sha3(dev::toBigEndian(u256(0x34)))));
 }
 
+BOOST_AUTO_TEST_CASE(return_string)
+{
+	char const* sourceCode = R"(
+		contract Main {
+			string public s;
+			function set(string _s) external {
+				s = _s;
+			}
+			function get1() returns (string r) {
+				return s;
+			}
+//			function get2() returns (string r) {
+//				r = s;
+//			}
+		}
+	)";
+	compileAndRun(sourceCode, 0, "Main");
+	string s("Julia");
+	bytes args = encodeArgs(u256(0x20), u256(s.length()), s);
+	BOOST_REQUIRE(callContractFunction("set(string)", asString(args)) == encodeArgs());
+	BOOST_CHECK(callContractFunction("get1()") == args);
+//	BOOST_CHECK(callContractFunction("get2()") == args);
+//	BOOST_CHECK(callContractFunction("s()") == args);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }

test/libsolidity/solidityExecutionFramework.h

@@ -174,11 +174,11 @@ protected:
 			BOOST_REQUIRE(m_state.addressHasCode(m_contractAddress));
 			BOOST_REQUIRE(!executive.call(m_contractAddress, m_sender, _value, m_gasPrice, &_data, m_gas));
 		}
-		BOOST_REQUIRE(executive.go());
+		BOOST_REQUIRE(executive.go(/* DEBUG eth::Executive::simpleTrace() */));
 		m_state.noteSending(m_sender);
 		executive.finalize();
-		m_gasUsed = executive.gasUsed();
-		m_output = std::move(res.output); // FIXME: Looks like Framework needs ExecutiveResult embedded
+		m_gasUsed = res.gasUsed;
+		m_output = std::move(res.output);
 		m_logs = executive.logs();
 	}