void ArrayUtils::clearArray(ArrayType const& _type) const
{
unsigned stackHeightStart = m_context.getStackHeight();
solAssert(_type.getLocation() == ArrayType::Location::Storage, "");
if (_type.getBaseType()->getStorageBytes() < 32)
{
solAssert(_type.getBaseType()->isValueType(), "Invalid storage size for non-value type.");
solAssert(_type.getBaseType()->getStorageSize() <= 1, "Invalid storage size for type.");
}
if (_type.getBaseType()->isValueType())
solAssert(_type.getBaseType()->getStorageSize() <= 1, "Invalid size for value type.");
m_context << eth::Instruction::POP; // remove byte offset
if (_type.isDynamicallySized())
clearDynamicArray(_type);
else if (_type.getLength() == 0 || _type.getBaseType()->getCategory() == Type::Category::Mapping)
m_context << eth::Instruction::POP;
else if (_type.getBaseType()->isValueType() && _type.getStorageSize() <= 5)
{
// unroll loop for small arrays @todo choose a good value
// Note that we loop over storage slots here, not elements.
for (unsigned i = 1; i < _type.getStorageSize(); ++i)
m_context
<< u256(0) << eth::Instruction::DUP2 << eth::Instruction::SSTORE
<< u256(1) << eth::Instruction::ADD;
m_context << u256(0) << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
}
else if (!_type.getBaseType()->isValueType() && _type.getLength() <= 4)
{
// unroll loop for small arrays @todo choose a good value
solAssert(_type.getBaseType()->getStorageBytes() >= 32, "Invalid storage size.");
for (unsigned i = 1; i < _type.getLength(); ++i)
{
m_context << u256(0);
StorageItem(m_context, *_type.getBaseType()).setToZero(SourceLocation(), false);
m_context
<< eth::Instruction::POP
<< u256(_type.getBaseType()->getStorageSize()) << eth::Instruction::ADD;
}
m_context << u256(0);
StorageItem(m_context, *_type.getBaseType()).setToZero(SourceLocation(), true);
}
else
{
m_context << eth::Instruction::DUP1 << _type.getLength();
convertLengthToSize(_type);
m_context << eth::Instruction::ADD << eth::Instruction::SWAP1;
if (_type.getBaseType()->getStorageBytes() < 32)
clearStorageLoop(IntegerType(256));
else
clearStorageLoop(*_type.getBaseType());
m_context << eth::Instruction::POP;
}
solAssert(m_context.getStackHeight() == stackHeightStart - 2, "");
}
void ArrayUtils::retrieveLength(ArrayType const& _arrayType) const
{
if (!_arrayType.isDynamicallySized())
m_context << _arrayType.getLength();
else
{
m_context << eth::Instruction::DUP1;
switch (_arrayType.getLocation())
{
case ArrayType::Location::CallData:
// length is stored on the stack
break;
case ArrayType::Location::Memory:
m_context << eth::Instruction::MLOAD;
break;
case ArrayType::Location::Storage:
m_context << eth::Instruction::SLOAD;
break;
}
}
}
void ArrayUtils::accessIndex(ArrayType const& _arrayType) const
{
ArrayType::Location location = _arrayType.getLocation();
eth::Instruction load =
location == ArrayType::Location::Storage ? eth::Instruction::SLOAD :
location == ArrayType::Location::Memory ? eth::Instruction::MLOAD :
eth::Instruction::CALLDATALOAD;
// retrieve length
if (!_arrayType.isDynamicallySized())
m_context << _arrayType.getLength();
else if (location == ArrayType::Location::CallData)
// length is stored on the stack
m_context << eth::Instruction::SWAP1;
else
m_context << eth::Instruction::DUP2 << load;
// stack: <base_ref> <index> <length>
// check out-of-bounds access
m_context << eth::Instruction::DUP2 << eth::Instruction::LT;
eth::AssemblyItem legalAccess = m_context.appendConditionalJump();
// out-of-bounds access throws exception (just STOP for now)
m_context << eth::Instruction::STOP;
m_context << legalAccess;
// stack: <base_ref> <index>
if (_arrayType.isByteArray())
switch (location)
{
case ArrayType::Location::Storage:
// byte array index storage lvalue on stack (goal):
// <ref> <byte_number> = <base_ref + index / 32> <index % 32>
m_context << u256(32) << eth::Instruction::SWAP2;
CompilerUtils(m_context).computeHashStatic();
// stack: 32 index data_ref
m_context
<< eth::Instruction::DUP3 << eth::Instruction::DUP3
<< eth::Instruction::DIV << eth::Instruction::ADD
// stack: 32 index (data_ref + index / 32)
<< eth::Instruction::SWAP2 << eth::Instruction::SWAP1
<< eth::Instruction::MOD;
break;
case ArrayType::Location::CallData:
// no lvalue, just retrieve the value
m_context
<< eth::Instruction::ADD << eth::Instruction::CALLDATALOAD
<< ((u256(0xff) << (256 - 8))) << eth::Instruction::AND;
break;
case ArrayType::Location::Memory:
solAssert(false, "Memory lvalues not yet implemented.");
}
else
{
// stack: <base_ref> <index>
m_context << eth::Instruction::SWAP1;
if (_arrayType.isDynamicallySized())
{
if (location == ArrayType::Location::Storage)
CompilerUtils(m_context).computeHashStatic();
else if (location == ArrayType::Location::Memory)
m_context << u256(32) << eth::Instruction::ADD;
}
// stack: <index> <data_ref>
switch (location)
{
case ArrayType::Location::CallData:
m_context
<< eth::Instruction::SWAP1 << _arrayType.getBaseType()->getCalldataEncodedSize()
<< eth::Instruction::MUL << eth::Instruction::ADD;
if (_arrayType.getBaseType()->isValueType())
CompilerUtils(m_context).loadFromMemoryDynamic(*_arrayType.getBaseType(), true, true, false);
break;
case ArrayType::Location::Storage:
m_context << eth::Instruction::SWAP1;
if (_arrayType.getBaseType()->getStorageBytes() <= 16)
{
// stack: <data_ref> <index>
// goal:
// <ref> <byte_number> = <base_ref + index / itemsPerSlot> <(index % itemsPerSlot) * byteSize>
unsigned byteSize = _arrayType.getBaseType()->getStorageBytes();
solAssert(byteSize != 0, "");
unsigned itemsPerSlot = 32 / byteSize;
m_context << u256(itemsPerSlot) << eth::Instruction::SWAP2;
// stack: itemsPerSlot index data_ref
m_context
<< eth::Instruction::DUP3 << eth::Instruction::DUP3
<< eth::Instruction::DIV << eth::Instruction::ADD
// stack: itemsPerSlot index (data_ref + index / itemsPerSlot)
<< eth::Instruction::SWAP2 << eth::Instruction::SWAP1
<< eth::Instruction::MOD
<< u256(byteSize) << eth::Instruction::MUL;
}
else
{
if (_arrayType.getBaseType()->getStorageSize() != 1)
m_context << _arrayType.getBaseType()->getStorageSize() << eth::Instruction::MUL;
m_context << eth::Instruction::ADD << u256(0);
}
break;
case ArrayType::Location::Memory:
solAssert(false, "Memory lvalues not yet implemented.");
}
}
}