path: root/CompilerUtils.cpp

/*
    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, unsigned _bytes, bool _leftAligned,
                                       bool _fromCalldata, bool _padToWordBoundaries)
{
    if (_bytes == 0)
    {
        m_context << u256(0);
        return 0;
    }
    eth::Instruction load = _fromCalldata ? eth::Instruction::CALLDATALOAD : eth::Instruction::MLOAD;
    solAssert(_bytes <= 32, "Memory load of more than 32 bytes requested.");
    if (_bytes == 32 || _padToWordBoundaries)
    {
        m_context << u256(_offset) << load;
        return 32;
    }
    else
    {
        // load data and add leading or trailing zeros by dividing/multiplying depending on alignment
        u256 shiftFactor = u256(1) << ((32 - _bytes) * 8);
        m_context << shiftFactor;
        if (_leftAligned)
            m_context << eth::Instruction::DUP1;
        m_context << u256(_offset) << load << eth::Instruction::DIV;
        if (_leftAligned)
            m_context << eth::Instruction::MUL;
        return _bytes;
    }
}

unsigned CompilerUtils::storeInMemory(unsigned _offset, unsigned _bytes, bool _leftAligned,
                                      bool _padToWordBoundaries)
{
    if (_bytes == 0)
    {
        m_context << eth::Instruction::POP;
        return 0;
    }
    solAssert(_bytes <= 32, "Memory store of more than 32 bytes requested.");
    if (_bytes != 32 && !_leftAligned && !_padToWordBoundaries)
        // shift the value accordingly before storing
        m_context << (u256(1) << ((32 - _bytes) * 8)) << eth::Instruction::MUL;
    m_context << u256(_offset) << eth::Instruction::MSTORE;
    return _padToWordBoundaries ? 32 : _bytes;
}

void CompilerUtils::moveToStackVariable(VariableDeclaration const& _variable)
{
    unsigned const stackPosition = m_context.baseToCurrentStackOffset(m_context.getBaseStackOffsetOfVariable(_variable));
    unsigned const size = _variable.getType()->getSizeOnStack();
    // 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, Type const& _type)
{
    if (_stackDepth > 16)
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("Stack too deep."));
    unsigned const size = _type.getSizeOnStack();
    for (unsigned i = 0; i < size; ++i)
        m_context << eth::dupInstruction(_stackDepth);
}

void CompilerUtils::popStackElement(Type const& _type)
{
    unsigned const size = _type.getSizeOnStack();
    for (unsigned i = 0; i < size; ++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;
}

}
}