path: root/LValue.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 2015
 * LValues for use in the expresison compiler.
 */

#include <libsolidity/LValue.h>
#include <libevmcore/Instruction.h>
#include <libsolidity/Types.h>
#include <libsolidity/AST.h>
#include <libsolidity/CompilerUtils.h>

using namespace std;
using namespace dev;
using namespace solidity;


StackVariable::StackVariable(CompilerContext& _compilerContext, Declaration const& _declaration):
    LValue(_compilerContext, *_declaration.getType()),
    m_baseStackOffset(m_context.getBaseStackOffsetOfVariable(_declaration)),
    m_size(m_dataType.getSizeOnStack())
{
}

void StackVariable::retrieveValue(SourceLocation const& _location, bool) const
{
    unsigned stackPos = m_context.baseToCurrentStackOffset(m_baseStackOffset);
    if (stackPos >= 15) //@todo correct this by fetching earlier or moving to memory
        BOOST_THROW_EXCEPTION(CompilerError()
            << errinfo_sourceLocation(_location) << errinfo_comment("Stack too deep."));
    for (unsigned i = 0; i < m_size; ++i)
        m_context << eth::dupInstruction(stackPos + 1);
}

void StackVariable::storeValue(Type const&, SourceLocation const& _location, bool _move) const
{
    unsigned stackDiff = m_context.baseToCurrentStackOffset(m_baseStackOffset) - m_size + 1;
    if (stackDiff > 16)
        BOOST_THROW_EXCEPTION(CompilerError()
            << errinfo_sourceLocation(_location) << errinfo_comment("Stack too deep."));
    else if (stackDiff > 0)
        for (unsigned i = 0; i < m_size; ++i)
            m_context << eth::swapInstruction(stackDiff) << eth::Instruction::POP;
    if (!_move)
        retrieveValue(_location);
}

void StackVariable::setToZero(SourceLocation const& _location, bool) const
{
    unsigned stackDiff = m_context.baseToCurrentStackOffset(m_baseStackOffset);
    if (stackDiff > 16)
        BOOST_THROW_EXCEPTION(CompilerError()
            << errinfo_sourceLocation(_location) << errinfo_comment("Stack too deep."));
    solAssert(stackDiff >= m_size - 1, "");
    for (unsigned i = 0; i < m_size; ++i)
        m_context << u256(0) << eth::swapInstruction(stackDiff + 1 - i)
            << eth::Instruction::POP;
}


StorageItem::StorageItem(CompilerContext& _compilerContext, Declaration const& _declaration):
    StorageItem(_compilerContext, *_declaration.getType())
{
    m_context << m_context.getStorageLocationOfVariable(_declaration);
}

StorageItem::StorageItem(CompilerContext& _compilerContext, Type const& _type):
    LValue(_compilerContext, _type)
{
    if (m_dataType.isValueType())
    {
        solAssert(m_dataType.getStorageSize() == m_dataType.getSizeOnStack(), "");
        solAssert(m_dataType.getStorageSize() <= numeric_limits<unsigned>::max(),
            "The storage size of " + m_dataType.toString() + " should fit in an unsigned");
        m_size = unsigned(m_dataType.getStorageSize());
    }
    else
        m_size = 0; // unused
}

void StorageItem::retrieveValue(SourceLocation const&, bool _remove) const
{
    if (!m_dataType.isValueType())
        return; // no distinction between value and reference for non-value types
    if (!_remove)
        m_context << eth::Instruction::DUP1;
    if (m_size == 1)
        m_context << eth::Instruction::SLOAD;
    else
        for (unsigned i = 0; i < m_size; ++i)
        {
            m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD << eth::Instruction::SWAP1;
            if (i + 1 < m_size)
                m_context << u256(1) << eth::Instruction::ADD;
            else
                m_context << eth::Instruction::POP;
        }
}

void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _location, bool _move) const
{
    // stack layout: value value ... value target_ref
    if (m_dataType.isValueType())
    {
        if (!_move) // copy values
        {
            if (m_size + 1 > 16)
                BOOST_THROW_EXCEPTION(CompilerError()
                    << errinfo_sourceLocation(_location) << errinfo_comment("Stack too deep."));
            for (unsigned i = 0; i < m_size; ++i)
                m_context << eth::dupInstruction(m_size + 1) << eth::Instruction::SWAP1;
        }
        if (m_size > 1) // store high index value first
            m_context << u256(m_size - 1) << eth::Instruction::ADD;
        for (unsigned i = 0; i < m_size; ++i)
        {
            if (i + 1 >= m_size)
                m_context << eth::Instruction::SSTORE;
            else
                // stack here: value value ... value value (target_ref+offset)
                m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2
                    << eth::Instruction::SSTORE
                    << u256(1) << eth::Instruction::SWAP1 << eth::Instruction::SUB;
        }
    }
    else
    {
        solAssert(_sourceType.getCategory() == m_dataType.getCategory(),
            "Wrong type conversation for assignment.");
        if (m_dataType.getCategory() == Type::Category::Array)
        {
            ArrayUtils(m_context).copyArrayToStorage(
                        dynamic_cast<ArrayType const&>(m_dataType),
                        dynamic_cast<ArrayType const&>(_sourceType));
            if (_move)
                m_context << eth::Instruction::POP;
        }
        else if (m_dataType.getCategory() == Type::Category::Struct)
        {
            // stack layout: source_ref target_ref
            auto const& structType = dynamic_cast<StructType const&>(m_dataType);
            solAssert(structType == _sourceType, "Struct assignment with conversion.");
            for (auto const& member: structType.getMembers())
            {
                // assign each member that is not a mapping
                TypePointer const& memberType = member.second;
                if (memberType->getCategory() == Type::Category::Mapping)
                    continue;
                m_context << structType.getStorageOffsetOfMember(member.first)
                    << eth::Instruction::DUP3 << eth::Instruction::DUP2 << eth::Instruction::ADD;
                // stack: source_ref target_ref member_offset source_member_ref
                StorageItem(m_context, *memberType).retrieveValue(_location, true);
                // stack: source_ref target_ref member_offset source_value...
                m_context << eth::dupInstruction(2 + memberType->getSizeOnStack())
                    << eth::dupInstruction(2 + memberType->getSizeOnStack()) << eth::Instruction::ADD;
                // stack: source_ref target_ref member_offset source_value... target_member_ref
                StorageItem(m_context, *memberType).storeValue(*memberType, _location, true);
                m_context << eth::Instruction::POP;
            }
            if (_move)
                m_context << eth::Instruction::POP;
            else
                m_context << eth::Instruction::SWAP1;
            m_context << eth::Instruction::POP;
        }
        else
            BOOST_THROW_EXCEPTION(InternalCompilerError()
                << errinfo_sourceLocation(_location) << errinfo_comment("Invalid non-value type for assignment."));
    }
}

void StorageItem::setToZero(SourceLocation const&, bool _removeReference) const
{
    if (m_dataType.getCategory() == Type::Category::Array)
    {
        if (!_removeReference)
            m_context << eth::Instruction::DUP1;
        ArrayUtils(m_context).clearArray(dynamic_cast<ArrayType const&>(m_dataType));
    }
    else if (m_dataType.getCategory() == Type::Category::Struct)
    {
        // stack layout: ref
        auto const& structType = dynamic_cast<StructType const&>(m_dataType);
        for (auto const& member: structType.getMembers())
        {
            // zero each member that is not a mapping
            TypePointer const& memberType = member.second;
            if (memberType->getCategory() == Type::Category::Mapping)
                continue;
            m_context << structType.getStorageOffsetOfMember(member.first)
                << eth::Instruction::DUP2 << eth::Instruction::ADD;
            StorageItem(m_context, *memberType).setToZero();
        }
        if (_removeReference)
            m_context << eth::Instruction::POP;
    }
    else
    {
        solAssert(m_dataType.isValueType(), "Clearing of unsupported type requested: " + m_dataType.toString());
        if (m_size == 0 && _removeReference)
            m_context << eth::Instruction::POP;
        else if (m_size == 1)
            m_context
                << u256(0) << (_removeReference ? eth::Instruction::SWAP1 : eth::Instruction::DUP2)
                << eth::Instruction::SSTORE;
        else
        {
            if (!_removeReference)
                m_context << eth::Instruction::DUP1;
            for (unsigned i = 0; i < m_size; ++i)
                if (i + 1 >= m_size)
                    m_context << u256(0) << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
                else
                    m_context << u256(0) << eth::Instruction::DUP2 << eth::Instruction::SSTORE
                        << u256(1) << eth::Instruction::ADD;
        }
    }
}

/// Used in StorageByteArrayElement
static IntegerType byteType(8, IntegerType::Modifier::Hash);

StorageByteArrayElement::StorageByteArrayElement(CompilerContext& _compilerContext):
    LValue(_compilerContext, byteType)
{
}

void StorageByteArrayElement::retrieveValue(SourceLocation const&, bool _remove) const
{
    // stack: ref byte_number
    if (_remove)
        m_context << eth::Instruction::SWAP1 << eth::Instruction::SLOAD
            << eth::Instruction::SWAP1 << eth::Instruction::BYTE;
    else
        m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD
            << eth::Instruction::DUP2 << eth::Instruction::BYTE;
}

void StorageByteArrayElement::storeValue(Type const&, SourceLocation const&, bool _move) const
{
    //@todo optimize this

    // stack: value ref byte_number
    m_context << u256(31) << eth::Instruction::SUB << u256(0x100) << eth::Instruction::EXP;
    // stack: value ref (1<<(8*(31-byte_number)))
    m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
    // stack: value ref (1<<(8*(31-byte_number))) old_full_value
    // clear byte in old value
    m_context << eth::Instruction::DUP2 << u256(0xff) << eth::Instruction::MUL
        << eth::Instruction::NOT << eth::Instruction::AND;
    // stack: value ref (1<<(32-byte_number)) old_full_value_with_cleared_byte
    m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP4 << eth::Instruction::MUL
        << eth::Instruction::OR;
    // stack: value ref new_full_value
    m_context << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
    if (_move)
        m_context << eth::Instruction::POP;
}

void StorageByteArrayElement::setToZero(SourceLocation const&, bool _removeReference) const
{
    // stack: ref byte_number
    if (!_removeReference)
        m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2;
    m_context << u256(31) << eth::Instruction::SUB << u256(0x100) << eth::Instruction::EXP;
    // stack: ref (1<<(8*(31-byte_number)))
    m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
    // stack: ref (1<<(8*(31-byte_number))) old_full_value
    // clear byte in old value
    m_context << eth::Instruction::SWAP1 << u256(0xff) << eth::Instruction::MUL << eth::Instruction::AND;
    // stack: ref old_full_value_with_cleared_byte
    m_context << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
    if (!_removeReference)
        m_context << eth::Instruction::SWAP1;
    else
        m_context << eth::Instruction::POP;
}

StorageArrayLength::StorageArrayLength(CompilerContext& _compilerContext, const ArrayType& _arrayType):
    LValue(_compilerContext, *_arrayType.getMemberType("length")),
    m_arrayType(_arrayType)
{
    solAssert(m_arrayType.isDynamicallySized(), "");
}

void StorageArrayLength::retrieveValue(SourceLocation const&, bool _remove) const
{
    if (!_remove)
        m_context << eth::Instruction::DUP1;
    m_context << eth::Instruction::SLOAD;
}

void StorageArrayLength::storeValue(Type const&, SourceLocation const&, bool _move) const
{
    if (_move)
        m_context << eth::Instruction::SWAP1;
    else
        m_context << eth::Instruction::DUP2;
    ArrayUtils(m_context).resizeDynamicArray(m_arrayType);
}

void StorageArrayLength::setToZero(SourceLocation const&, bool _removeReference) const
{
    if (!_removeReference)
        m_context << eth::Instruction::DUP1;
    ArrayUtils(m_context).clearDynamicArray(m_arrayType);
}