/*
This file is part of cpp-ethereum.
cpp-ethereum is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
cpp-ethereum is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @author Christian <c@ethdev.com>
* @date 2014
* Routines used by both the compiler and the expression compiler.
*/
#include <libsolidity/CompilerUtils.h>
#include <libsolidity/AST.h>
#include <libevmcore/Instruction.h>
using namespace std;
namespace dev
{
namespace solidity
{
const unsigned int CompilerUtils::dataStartOffset = 4;
unsigned CompilerUtils::loadFromMemory(
unsigned _offset,
Type const& _type,
bool _fromCalldata,
bool _padToWordBoundaries
)
{
solAssert(_type.getCategory() != Type::Category::Array, "Unable to statically load dynamic type.");
m_context << u256(_offset);
return loadFromMemoryHelper(_type, _fromCalldata, _padToWordBoundaries);
}
void CompilerUtils::loadFromMemoryDynamic(
Type const& _type,
bool _fromCalldata,
bool _padToWordBoundaries,
bool _keepUpdatedMemoryOffset
)
{
solAssert(_type.getCategory() != Type::Category::Array, "Arrays not yet implemented.");
if (_keepUpdatedMemoryOffset)
m_context << eth::Instruction::DUP1;
unsigned numBytes = loadFromMemoryHelper(_type, _fromCalldata, _padToWordBoundaries);
if (_keepUpdatedMemoryOffset)
{
// update memory counter
for (unsigned i = 0; i < _type.getSizeOnStack(); ++i)
m_context << eth::swapInstruction(1 + i);
m_context << u256(numBytes) << eth::Instruction::ADD;
}
}
unsigned CompilerUtils::storeInMemory(unsigned _offset, Type const& _type, bool _padToWordBoundaries)
{
solAssert(_type.getCategory() != Type::Category::Array, "Unable to statically store dynamic type.");
unsigned numBytes = prepareMemoryStore(_type, _padToWordBoundaries);
if (numBytes > 0)
m_context << u256(_offset) << eth::Instruction::MSTORE;
return numBytes;
}
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.getLocation() == ArrayType::Location::CallData)
{
// 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
<< eth::Instruction::CALLDATACOPY
<< eth::Instruction::DUP3 << eth::Instruction::ADD
<< eth::Instruction::SWAP2 << eth::Instruction::POP << eth::Instruction::POP;
}
else
{
solAssert(type.getLocation() == ArrayType::Location::Storage, "Memory arrays not yet implemented.");
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
<< 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.appendConditionalJumpTo(loopStart);
m_context << loopEnd << eth::Instruction::POP << eth::Instruction::POP;
}
}
else
{
unsigned numBytes = prepareMemoryStore(_type, _padToWordBoundaries);
if (numBytes > 0)
{
solAssert(_type.getSizeOnStack() == 1, "Memory store of types with stack size != 1 not implemented.");
m_context << eth::Instruction::DUP2 << eth::Instruction::MSTORE;
m_context << u256(numBytes) << eth::Instruction::ADD;
}
}
}
void CompilerUtils::moveToStackVariable(VariableDeclaration const& _variable)
{
unsigned const stackPosition = m_context.baseToCurrentStackOffset(m_context.getBaseStackOffsetOfVariable(_variable));
unsigned const size = _variable.getType()->getSizeOnStack();
solAssert(stackPosition >= size, "Variable size and position mismatch.");
// move variable starting from its top end in the stack
if (stackPosition - size + 1 > 16)
BOOST_THROW_EXCEPTION(CompilerError() << errinfo_sourceLocation(_variable.getLocation())
<< errinfo_comment("Stack too deep."));
for (unsigned i = 0; i < size; ++i)
m_context << eth::swapInstruction(stackPosition - size + 1) << eth::Instruction::POP;
}
void CompilerUtils::copyToStackTop(unsigned _stackDepth, unsigned _itemSize)
{
solAssert(_stackDepth <= 16, "Stack too deep.");
for (unsigned i = 0; i < _itemSize; ++i)
m_context << eth::dupInstruction(_stackDepth);
}
void CompilerUtils::moveToStackTop(unsigned _stackDepth)
{
solAssert(_stackDepth <= 15, "Stack too deep.");
for (unsigned i = 0; i < _stackDepth; ++i)
m_context << eth::swapInstruction(1 + i);
}
void CompilerUtils::popStackElement(Type const& _type)
{
popStackSlots(_type.getSizeOnStack());
}
void CompilerUtils::popStackSlots(size_t _amount)
{
for (size_t i = 0; i < _amount; ++i)
m_context << eth::Instruction::POP;
}
unsigned CompilerUtils::getSizeOnStack(vector<shared_ptr<Type const>> const& _variableTypes)
{
unsigned size = 0;
for (shared_ptr<Type const> const& type: _variableTypes)
size += type->getSizeOnStack();
return size;
}
void CompilerUtils::computeHashStatic(Type const& _type, bool _padToWordBoundaries)
{
unsigned length = storeInMemory(0, _type, _padToWordBoundaries);
m_context << u256(length) << u256(0) << eth::Instruction::SHA3;
}
unsigned CompilerUtils::loadFromMemoryHelper(Type const& _type, bool _fromCalldata, bool _padToWordBoundaries)
{
unsigned numBytes = _type.getCalldataEncodedSize(_padToWordBoundaries);
bool leftAligned = _type.getCategory() == Type::Category::FixedBytes;
if (numBytes == 0)
m_context << eth::Instruction::POP << u256(0);
else
{
solAssert(numBytes <= 32, "Static memory load of more than 32 bytes requested.");
m_context << (_fromCalldata ? eth::Instruction::CALLDATALOAD : eth::Instruction::MLOAD);
if (numBytes != 32)
{
// add leading or trailing zeros by dividing/multiplying depending on alignment
u256 shiftFactor = u256(1) << ((32 - numBytes) * 8);
m_context << shiftFactor << eth::Instruction::SWAP1 << eth::Instruction::DIV;
if (leftAligned)
m_context << shiftFactor << eth::Instruction::MUL;
}
}
return numBytes;
}
unsigned CompilerUtils::prepareMemoryStore(Type const& _type, bool _padToWordBoundaries) const
{
unsigned numBytes = _type.getCalldataEncodedSize(_padToWordBoundaries);
bool leftAligned = _type.getCategory() == Type::Category::FixedBytes;
if (numBytes == 0)
m_context << eth::Instruction::POP;
else
{
solAssert(numBytes <= 32, "Memory store of more than 32 bytes requested.");
if (numBytes != 32 && !leftAligned && !_padToWordBoundaries)
// shift the value accordingly before storing
m_context << (u256(1) << ((32 - numBytes) * 8)) << eth::Instruction::MUL;
}
return numBytes;
}
}
}
