Merge pull request #2276 from chriseth/sol_memoryArrays7

Copy routines for non-byte arrays.

12 files changed, 324 insertions, 144 deletions

diff --git a/ArrayUtils.cpp b/ArrayUtils.cpp
index e138e951..3be12af7 100644
--- a/ArrayUtils.cpp
+++ b/ArrayUtils.cpp
@@ -231,6 +231,181 @@ void ArrayUtils::copyArrayToStorage(ArrayType const& _targetType, ArrayType cons
 	m_context << u256(0);
 }
 
+void ArrayUtils::copyArrayToMemory(const ArrayType& _sourceType, bool _padToWordBoundaries) const
+{
+	solAssert(
+		_sourceType.getBaseType()->getCalldataEncodedSize() > 0,
+		"Nested arrays not yet implemented here."
+	);
+	unsigned baseSize = 1;
+	if (!_sourceType.isByteArray())
+		// We always pad the elements, regardless of _padToWordBoundaries.
+		baseSize = _sourceType.getBaseType()->getCalldataEncodedSize();
+
+	if (_sourceType.location() == DataLocation::CallData)
+	{
+		if (!_sourceType.isDynamicallySized())
+			m_context << _sourceType.getLength();
+		if (_sourceType.getBaseType()->getCalldataEncodedSize() > 1)
+			m_context << u256(baseSize) << eth::Instruction::MUL;
+		// stack: target source_offset source_len
+		m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3 << eth::Instruction::DUP5;
+		// stack: target source_offset source_len source_len source_offset target
+		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 (_sourceType.location() == DataLocation::Memory)
+	{
+		// memcpy using the built-in contract
+		retrieveLength(_sourceType);
+		if (_sourceType.isDynamicallySized())
+		{
+			// change pointer to data part
+			m_context << eth::Instruction::SWAP1 << u256(32) << eth::Instruction::ADD;
+			m_context << eth::Instruction::SWAP1;
+		}
+		// convert length to size
+		if (baseSize > 1)
+			m_context << u256(baseSize) << eth::Instruction::MUL;
+		// stack: <target> <source> <size>
+		//@TODO do not use ::CALL if less than 32 bytes?
+		m_context << eth::Instruction::DUP1 << eth::Instruction::DUP4 << eth::Instruction::DUP4;
+		CompilerUtils(m_context).memoryCopy();
+
+		m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
+		// stack: <target> <size>
+
+		bool paddingNeeded = false;
+		if (_sourceType.isDynamicallySized())
+			paddingNeeded = _padToWordBoundaries && ((baseSize % 32) != 0);
+		else
+			paddingNeeded = _padToWordBoundaries && (((_sourceType.getLength() * baseSize) % 32) != 0);
+		if (paddingNeeded)
+		{
+			// stack: <target> <size>
+			m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2 << eth::Instruction::ADD;
+			// stack: <length> <target + size>
+			m_context << eth::Instruction::SWAP1 << u256(31) << eth::Instruction::AND;
+			// stack: <target + size> <remainder = size % 32>
+			eth::AssemblyItem skip = m_context.newTag();
+			if (_sourceType.isDynamicallySized())
+			{
+				m_context << eth::Instruction::DUP1 << eth::Instruction::ISZERO;
+				m_context.appendConditionalJumpTo(skip);
+			}
+			// round off, load from there.
+			// stack <target + size> <remainder = size % 32>
+			m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3;
+			m_context << eth::Instruction::SUB;
+			// stack: target+size remainder <target + size - 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+size remainder target+size-remainder <v & ...>
+			m_context << eth::Instruction::DUP2 << eth::Instruction::MSTORE;
+			// stack: target+size remainder target+size-remainder
+			m_context << u256(32) << eth::Instruction::ADD;
+			// stack: target+size remainder <new_padded_end>
+			m_context << eth::Instruction::SWAP2 << eth::Instruction::POP;
+
+			if (_sourceType.isDynamicallySized())
+				m_context << skip.tag();
+			// stack <target + "size"> <remainder = size % 32>
+			m_context << eth::Instruction::POP;
+		}
+		else
+			// stack: <target> <size>
+			m_context << eth::Instruction::ADD;
+	}
+	else
+	{
+		solAssert(_sourceType.location() == DataLocation::Storage, "");
+		unsigned storageBytes = _sourceType.getBaseType()->getStorageBytes();
+		u256 storageSize = _sourceType.getBaseType()->getStorageSize();
+		solAssert(storageSize > 1 || (storageSize == 1 && storageBytes > 0), "");
+
+		m_context << eth::Instruction::POP; // remove offset, arrays always start new slot
+		retrieveLength(_sourceType);
+		// stack here: memory_offset storage_offset length
+		// jump to end if length is zero
+		m_context << eth::Instruction::DUP1 << eth::Instruction::ISZERO;
+		eth::AssemblyItem loopEnd = m_context.newTag();
+		m_context.appendConditionalJumpTo(loopEnd);
+		// compute memory end offset
+		if (baseSize > 1)
+			// convert length to memory size
+			m_context << u256(baseSize) << eth::Instruction::MUL;
+		m_context << eth::Instruction::DUP3 << eth::Instruction::ADD << eth::Instruction::SWAP2;
+		if (_sourceType.isDynamicallySized())
+		{
+			// actual array data is stored at SHA3(storage_offset)
+			m_context << eth::Instruction::SWAP1;
+			CompilerUtils(m_context).computeHashStatic();
+			m_context << eth::Instruction::SWAP1;
+		}
+
+		// stack here: memory_end_offset storage_data_offset memory_offset
+		bool haveByteOffset = !_sourceType.isByteArray() && storageBytes <= 16;
+		if (haveByteOffset)
+			m_context << u256(0) << eth::Instruction::SWAP1;
+		// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
+		eth::AssemblyItem loopStart = m_context.newTag();
+		m_context << loopStart;
+		// load and store
+		if (_sourceType.isByteArray())
+		{
+			// Packed both in storage and memory.
+			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;
+		}
+		else
+		{
+			// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
+			if (haveByteOffset)
+				m_context << eth::Instruction::DUP3 << eth::Instruction::DUP3;
+			else
+				m_context << eth::Instruction::DUP2 << u256(0);
+			StorageItem(m_context, *_sourceType.getBaseType()).retrieveValue(SourceLocation(), true);
+			CompilerUtils(m_context).storeInMemoryDynamic(*_sourceType.getBaseType());
+			// increment storage_data_offset and byte offset
+			if (haveByteOffset)
+				incrementByteOffset(storageBytes, 2, 3);
+			else
+			{
+				m_context << eth::Instruction::SWAP1;
+				m_context << storageSize << eth::Instruction::ADD;
+				m_context << eth::Instruction::SWAP1;
+			}
+		}
+		// check for loop condition
+		m_context << eth::Instruction::DUP1 << eth::dupInstruction(haveByteOffset ? 5 : 4) << eth::Instruction::GT;
+		m_context.appendConditionalJumpTo(loopStart);
+		// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
+		if (haveByteOffset)
+			m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
+		if (_padToWordBoundaries && baseSize % 32 != 0)
+		{
+			// 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;
+	}
+}
+
 void ArrayUtils::clearArray(ArrayType const& _type) const
 {
 	unsigned stackHeightStart = m_context.getStackHeight();
@@ -499,6 +674,8 @@ void ArrayUtils::accessIndex(ArrayType const& _arrayType) const
 			m_context << _arrayType.getBaseType()->getCalldataEncodedSize() << eth::Instruction::MUL;
 		}
 		m_context << eth::Instruction::ADD;
+		//@todo we should also load if it is a reference type of dynamic length
+		// but we should apply special logic if we load from calldata.
 		if (_arrayType.getBaseType()->isValueType())
 			CompilerUtils(m_context).loadFromMemoryDynamic(
 				*_arrayType.getBaseType(),
diff --git a/ArrayUtils.h b/ArrayUtils.h
index dab40e2d..8d56f3c8 100644
--- a/ArrayUtils.h
+++ b/ArrayUtils.h
@@ -44,6 +44,10 @@ public:
 	/// Stack pre: source_reference [source_byte_offset/source_length] target_reference target_byte_offset
 	/// Stack post: target_reference target_byte_offset
 	void copyArrayToStorage(ArrayType const& _targetType, ArrayType const& _sourceType) const;
+	/// Copies an array (which cannot be dynamically nested) from anywhere to memory.
+	/// Stack pre: memory_offset source_item
+	/// Stack post: memory_offest + length(padded)
+	void copyArrayToMemory(ArrayType const& _sourceType, bool _padToWordBoundaries = true) const;
 	/// Clears the given dynamic or static array.
 	/// Stack pre: storage_ref storage_byte_offset
 	/// Stack post:
diff --git a/Compiler.cpp b/Compiler.cpp
index f5570b98..b05a7a9b 100644
--- a/Compiler.cpp
+++ b/Compiler.cpp
@@ -392,9 +392,9 @@ bool Compiler::visit(FunctionDefinition const& _function)
 	}
 
 	for (ASTPointer<VariableDeclaration const> const& variable: _function.getReturnParameters())
-		m_context.addAndInitializeVariable(*variable);
+		appendStackVariableInitialisation(*variable);
 	for (VariableDeclaration const* localVariable: _function.getLocalVariables())
-		m_context.addAndInitializeVariable(*localVariable);
+		appendStackVariableInitialisation(*localVariable);
 
 	if (_function.isConstructor())
 		if (auto c = m_context.getNextConstructor(dynamic_cast<ContractDefinition const&>(*_function.getScope())))
@@ -639,7 +639,7 @@ void Compiler::appendModifierOrFunctionCode()
 							  modifier.getParameters()[i]->getType());
 		}
 		for (VariableDeclaration const* localVariable: modifier.getLocalVariables())
-			m_context.addAndInitializeVariable(*localVariable);
+			appendStackVariableInitialisation(*localVariable);
 
 		unsigned const c_stackSurplus = CompilerUtils::getSizeOnStack(modifier.getParameters()) +
 										CompilerUtils::getSizeOnStack(modifier.getLocalVariables());
@@ -653,6 +653,13 @@ void Compiler::appendModifierOrFunctionCode()
 	}
 }
 
+void Compiler::appendStackVariableInitialisation(VariableDeclaration const& _variable)
+{
+	CompilerContext::LocationSetter location(m_context, _variable);
+	m_context.addVariable(_variable);
+	ExpressionCompiler(m_context).appendStackVariableInitialisation(*_variable.getType());
+}
+
 void Compiler::compileExpression(Expression const& _expression, TypePointer const& _targetType)
 {
 	ExpressionCompiler expressionCompiler(m_context, m_optimize);
diff --git a/Compiler.h b/Compiler.h
index 60ca00e8..ac794f89 100644
--- a/Compiler.h
+++ b/Compiler.h
@@ -84,6 +84,13 @@ private:
 	void registerStateVariables(ContractDefinition const& _contract);
 	void initializeStateVariables(ContractDefinition const& _contract);
 
+	/// Initialises all memory arrays in the local variables to point to an empty location.
+	void initialiseMemoryArrays(std::vector<VariableDeclaration const*> _variables);
+	/// Pushes the initialised value of the given type to the stack. If the type is a memory
+	/// reference type, allocates memory and pushes the memory pointer.
+	/// Not to be used for storage references.
+	void initialiseInMemory(Type const& _type);
+
 	virtual bool visit(VariableDeclaration const& _variableDeclaration) override;
 	virtual bool visit(FunctionDefinition const& _function) override;
 	virtual bool visit(IfStatement const& _ifStatement) override;
@@ -100,6 +107,7 @@ private:
 	/// body itself if the last modifier was reached.
 	void appendModifierOrFunctionCode();
 
+	void appendStackVariableInitialisation(VariableDeclaration const& _variable);
 	void compileExpression(Expression const& _expression, TypePointer const& _targetType = TypePointer());
 
 	bool const m_optimize;
diff --git a/CompilerContext.cpp b/CompilerContext.cpp
index fde6adac..0f6f5fe7 100644
--- a/CompilerContext.cpp
+++ b/CompilerContext.cpp
@@ -65,15 +65,6 @@ void CompilerContext::removeVariable(VariableDeclaration const& _declaration)
 	m_localVariables.erase(&_declaration);
 }
 
-void CompilerContext::addAndInitializeVariable(VariableDeclaration const& _declaration)
-{
-	LocationSetter locationSetter(*this, _declaration);
-	addVariable(_declaration);
-	int const size = _declaration.getType()->getSizeOnStack();
-	for (int i = 0; i < size; ++i)
-		*this << u256(0);
-}
-
 bytes const& CompilerContext::getCompiledContract(const ContractDefinition& _contract) const
 {
 	auto ret = m_compiledContracts.find(&_contract);
diff --git a/CompilerContext.h b/CompilerContext.h
index 998b0a2f..3f97d900 100644
--- a/CompilerContext.h
+++ b/CompilerContext.h
@@ -46,7 +46,6 @@ public:
 	void addStateVariable(VariableDeclaration const& _declaration, u256 const& _storageOffset, unsigned _byteOffset);
 	void addVariable(VariableDeclaration const& _declaration, unsigned _offsetToCurrent = 0);
 	void removeVariable(VariableDeclaration const& _declaration);
-	void addAndInitializeVariable(VariableDeclaration const& _declaration);
 
 	void setCompiledContracts(std::map<ContractDefinition const*, bytes const*> const& _contracts) { m_compiledContracts = _contracts; }
 	bytes const& getCompiledContract(ContractDefinition const& _contract) const;
diff --git a/CompilerUtils.cpp b/CompilerUtils.cpp
index e763a394..47a9a354 100644
--- a/CompilerUtils.cpp
+++ b/CompilerUtils.cpp
@@ -25,6 +25,7 @@
 #include <libevmcore/Instruction.h>
 #include <libevmcore/Params.h>
 #include <libsolidity/ArrayUtils.h>
+#include <libsolidity/LValue.h>
 
 using namespace std;
 
@@ -101,130 +102,10 @@ void CompilerUtils::storeInMemory(unsigned _offset)
 void CompilerUtils::storeInMemoryDynamic(Type const& _type, bool _padToWordBoundaries)
 {
 	if (_type.getCategory() == Type::Category::Array)
-	{
-		auto const& type = dynamic_cast<ArrayType const&>(_type);
-		solAssert(type.isByteArray(), "Non byte arrays not yet implemented here.");
-
-		if (type.location() == DataLocation::CallData)
-		{
-			if (!type.isDynamicallySized())
-				m_context << type.getLength();
-			// stack: target source_offset source_len
-			m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3 << eth::Instruction::DUP5;
-			// stack: target source_offset source_len source_len source_offset target
-			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() == DataLocation::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 + 15 + 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() == DataLocation::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
-			// jump to end if length is zero
-			m_context << eth::Instruction::DUP1 << eth::Instruction::ISZERO;
-			eth::AssemblyItem loopEnd = m_context.newTag();
-			m_context.appendConditionalJumpTo(loopEnd);
-			// compute memory end offset
-			m_context << eth::Instruction::DUP3 << eth::Instruction::ADD << eth::Instruction::SWAP2;
-			// actual array data is stored at SHA3(storage_offset)
-			m_context << eth::Instruction::SWAP1;
-			CompilerUtils(m_context).computeHashStatic();
-			m_context << eth::Instruction::SWAP1;
-
-			// stack here: memory_end_offset storage_data_offset memory_offset
-			eth::AssemblyItem loopStart = m_context.newTag();
-			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;
-		}
-	}
+		ArrayUtils(m_context).copyArrayToMemory(
+			dynamic_cast<ArrayType const&>(_type),
+			_padToWordBoundaries
+		);
 	else
 	{
 		unsigned numBytes = prepareMemoryStore(_type, _padToWordBoundaries);
@@ -339,6 +220,21 @@ void CompilerUtils::encodeToMemory(
 	popStackSlots(argSize + dynPointers + 1);
 }
 
+void CompilerUtils::memoryCopy()
+{
+	// Stack here: size target source
+	// stack for call: outsize target size source value contract gas
+	//@TODO do not use ::CALL if less than 32 bytes?
+	m_context << eth::Instruction::DUP3 << eth::Instruction::SWAP1;
+	m_context << u256(0) << u256(identityContractAddress);
+	// compute gas costs
+	m_context << u256(32) << eth::Instruction::DUP5 << u256(31) << eth::Instruction::ADD;
+	m_context << eth::Instruction::DIV << u256(eth::c_identityWordGas) << eth::Instruction::MUL;
+	m_context << u256(eth::c_identityGas) << eth::Instruction::ADD;
+	m_context << eth::Instruction::CALL;
+	m_context << eth::Instruction::POP; // ignore return value
+}
+
 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
@@ -513,7 +409,14 @@ void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetTyp
 			break;
 		}
 		default:
-			solAssert(false, "Invalid type conversion requested.");
+			solAssert(
+				false,
+				"Invalid type conversion " +
+				_typeOnStack.toString(false) +
+				" to " +
+				_targetType.toString(false) +
+				" requested."
+			);
 		}
 		break;
 	}
diff --git a/CompilerUtils.h b/CompilerUtils.h
index 9a599f7f..a9e07f74 100644
--- a/CompilerUtils.h
+++ b/CompilerUtils.h
@@ -71,6 +71,8 @@ public:
 	void storeInMemory(unsigned _offset);
 	/// Dynamic version of @see storeInMemory, expects the memory offset below the value on the stack
 	/// and also updates that. For arrays, only copies the data part.
+	/// @param _padToWordBoundaries if true, adds zeros to pad to multiple of 32 bytes. Array elements
+	/// are always padded (except for byte arrays), regardless of this parameter.
 	/// Stack pre: memory_offset value...
 	/// Stack post: (memory_offset+length)
 	void storeInMemoryDynamic(Type const& _type, bool _padToWordBoundaries = true);
@@ -93,6 +95,11 @@ public:
 		bool _copyDynamicDataInPlace = false
 	);
 
+	/// Uses a CALL to the identity contract to perform a memory-to-memory copy.
+	/// Stack pre: <size> <target> <source>
+	/// Stack post:
+	void memoryCopy();
+
 	/// 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/ExpressionCompiler.cpp b/ExpressionCompiler.cpp
index 7d6ed346..fb10eb83 100644
--- a/ExpressionCompiler.cpp
+++ b/ExpressionCompiler.cpp
@@ -56,6 +56,62 @@ void ExpressionCompiler::appendStateVariableInitialization(VariableDeclaration c
 	StorageItem(m_context, _varDecl).storeValue(*_varDecl.getType(), _varDecl.getLocation(), true);
 }
 
+void ExpressionCompiler::appendStackVariableInitialisation(Type const& _type, bool _toMemory)
+{
+	CompilerUtils utils(m_context);
+	auto const* referenceType = dynamic_cast<ReferenceType const*>(&_type);
+	if (!referenceType || referenceType->location() == DataLocation::Storage)
+	{
+		for (size_t i = 0; i < _type.getSizeOnStack(); ++i)
+			m_context << u256(0);
+		if (_toMemory)
+			utils.storeInMemoryDynamic(_type);
+		return;
+	}
+	solAssert(referenceType->location() == DataLocation::Memory, "");
+	if (!_toMemory)
+	{
+		// allocate memory
+		utils.fetchFreeMemoryPointer();
+		m_context << eth::Instruction::DUP1 << u256(max(32u, _type.getCalldataEncodedSize()));
+		m_context << eth::Instruction::ADD;
+		utils.storeFreeMemoryPointer();
+		m_context << eth::Instruction::DUP1;
+	}
+
+	if (auto structType = dynamic_cast<StructType const*>(&_type))
+		for (auto const& member: structType->getMembers())
+			appendStackVariableInitialisation(*member.type, true);
+	else if (auto arrayType = dynamic_cast<ArrayType const*>(&_type))
+	{
+		if (arrayType->isDynamicallySized())
+		{
+			// zero length
+			m_context << u256(0);
+			CompilerUtils(m_context).storeInMemoryDynamic(IntegerType(256));
+		}
+		else if (arrayType->getLength() > 0)
+		{
+			m_context << arrayType->getLength() << eth::Instruction::SWAP1;
+			// stack: items_to_do memory_pos
+			auto repeat = m_context.newTag();
+			m_context << repeat;
+			appendStackVariableInitialisation(*arrayType->getBaseType(), true);
+			m_context << eth::Instruction::SWAP1 << u256(1) << eth::Instruction::SWAP1;
+			m_context << eth::Instruction::SUB << eth::Instruction::SWAP1;
+			m_context << eth::Instruction::DUP2;
+			m_context.appendConditionalJumpTo(repeat);
+			m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
+		}
+	}
+	else
+		solAssert(false, "Requested initialisation for unknown type: " + _type.toString());
+
+	if (!_toMemory)
+		// remove the updated memory pointer
+		m_context << eth::Instruction::POP;
+}
+
 void ExpressionCompiler::appendStateVariableAccessor(VariableDeclaration const& _varDecl)
 {
 	CompilerContext::LocationSetter locationSetter(m_context, _varDecl);
diff --git a/ExpressionCompiler.h b/ExpressionCompiler.h
index 642560c6..747e241e 100644
--- a/ExpressionCompiler.h
+++ b/ExpressionCompiler.h
@@ -64,6 +64,13 @@ public:
 	/// Appends code to set a state variable to its initial value/expression.
 	void appendStateVariableInitialization(VariableDeclaration const& _varDecl);
 
+	/// Appends code to initialise a local variable.
+	/// If @a _toMemory is false, leaves the value on the stack. For memory references, this
+	/// allocates new memory.
+	/// If @a _toMemory is true, directly stores the data in the memory pos on the stack and
+	/// updates it.
+	void appendStackVariableInitialisation(Type const& _type, bool _toMemory = false);
+
 	/// Appends code for a State Variable accessor function
 	void appendStateVariableAccessor(VariableDeclaration const& _varDecl);
 
diff --git a/Types.cpp b/Types.cpp
index 10a59826..01876b5a 100644
--- a/Types.cpp
+++ b/Types.cpp
@@ -721,9 +721,13 @@ bool ArrayType::isImplicitlyConvertibleTo(const Type& _convertTo) const
 	}
 	else
 	{
-		// Require that the base type is the same, not only convertible.
-		// This disallows assignment of nested arrays from storage to memory for now.
-		if (*getBaseType() != *convertTo.getBaseType())
+		// Conversion to storage pointer or to memory, we de not copy element-for-element here, so
+		// require that the base type is the same, not only convertible.
+		// This disallows assignment of nested dynamic arrays from storage to memory for now.
+		if (
+			*copyForLocationIfReference(location(), getBaseType()) !=
+			*copyForLocationIfReference(location(), convertTo.getBaseType())
+		)
 			return false;
 		if (isDynamicallySized() != convertTo.isDynamicallySized())
 			return false;
@@ -822,16 +826,16 @@ string ArrayType::toString(bool _short) const
 TypePointer ArrayType::externalType() const
 {
 	if (m_arrayKind != ArrayKind::Ordinary)
-		return this->copyForLocation(DataLocation::CallData, true);
+		return this->copyForLocation(DataLocation::Memory, true);
 	if (!m_baseType->externalType())
 		return TypePointer();
 	if (m_baseType->getCategory() == Category::Array && m_baseType->isDynamicallySized())
 		return TypePointer();
 
 	if (isDynamicallySized())
-		return std::make_shared<ArrayType>(DataLocation::CallData, m_baseType->externalType());
+		return std::make_shared<ArrayType>(DataLocation::Memory, m_baseType->externalType());
 	else
-		return std::make_shared<ArrayType>(DataLocation::CallData, m_baseType->externalType(), m_length);
+		return std::make_shared<ArrayType>(DataLocation::Memory, m_baseType->externalType(), m_length);
 }
 
 TypePointer ArrayType::copyForLocation(DataLocation _location, bool _isPointer) const
@@ -970,6 +974,22 @@ bool StructType::operator==(Type const& _other) const
 	return ReferenceType::operator==(other) && other.m_struct == m_struct;
 }
 
+unsigned StructType::getCalldataEncodedSize(bool _padded) const
+{
+	unsigned size = 0;
+	for (auto const& member: getMembers())
+		if (!member.type->canLiveOutsideStorage())
+			return 0;
+		else
+		{
+			unsigned memberSize = member.type->getCalldataEncodedSize(_padded);
+			if (memberSize == 0)
+				return 0;
+			size += memberSize;
+		}
+	return size;
+}
+
 u256 StructType::getStorageSize() const
 {
 	return max<u256>(1, getMembers().getStorageSize());
diff --git a/Types.h b/Types.h
index 7f66b5b0..9d412cd6 100644
--- a/Types.h
+++ b/Types.h
@@ -542,6 +542,7 @@ public:
 	virtual bool isImplicitlyConvertibleTo(const Type& _convertTo) const override;
 	virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
 	virtual bool operator==(Type const& _other) const override;
+	virtual unsigned getCalldataEncodedSize(bool _padded) const override;
 	virtual u256 getStorageSize() const override;
 	virtual bool canLiveOutsideStorage() const override;
 	virtual unsigned getSizeOnStack() const override { return 2; }