path: root/libsolidity/codegen/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/codegen/LValue.h>
#include <libevmasm/Instruction.h>
#include <libsolidity/ast/Types.h>
#include <libsolidity/ast/AST.h>
#include <libsolidity/codegen/CompilerUtils.h>

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


StackVariable::StackVariable(CompilerContext& _compilerContext, VariableDeclaration const& _declaration):
    LValue(_compilerContext, _declaration.annotation().type.get()),
    m_baseStackOffset(m_context.baseStackOffsetOfVariable(_declaration)),
    m_size(m_dataType->sizeOnStack())
{
}

void StackVariable::retrieveValue(SourceLocation const& _location, bool) const
{
    unsigned stackPos = m_context.baseToCurrentStackOffset(m_baseStackOffset);
    if (stackPos + 1 > 16) //@todo correct this by fetching earlier or moving to memory
        BOOST_THROW_EXCEPTION(
            CompilerError() <<
            errinfo_sourceLocation(_location) <<
            errinfo_comment("Stack too deep, try removing local variables.")
        );
    solAssert(stackPos + 1 >= m_size, "Size and stack pos mismatch.");
    for (unsigned i = 0; i < m_size; ++i)
        m_context << 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, try removing local variables.")
        );
    else if (stackDiff > 0)
        for (unsigned i = 0; i < m_size; ++i)
            m_context << swapInstruction(stackDiff) << Instruction::POP;
    if (!_move)
        retrieveValue(_location);
}

void StackVariable::setToZero(SourceLocation const& _location, bool) const
{
    CompilerUtils(m_context).pushZeroValue(*m_dataType);
    storeValue(*m_dataType, _location, true);
}

MemoryItem::MemoryItem(CompilerContext& _compilerContext, Type const& _type, bool _padded):
    LValue(_compilerContext, &_type),
    m_padded(_padded)
{
}

void MemoryItem::retrieveValue(SourceLocation const&, bool _remove) const
{
    if (m_dataType->isValueType())
    {
        if (!_remove)
            m_context << Instruction::DUP1;
        CompilerUtils(m_context).loadFromMemoryDynamic(*m_dataType, false, m_padded, false);
    }
    else
        m_context << Instruction::MLOAD;
}

void MemoryItem::storeValue(Type const& _sourceType, SourceLocation const&, bool _move) const
{
    CompilerUtils utils(m_context);
    if (m_dataType->isValueType())
    {
        solAssert(_sourceType.isValueType(), "");
        utils.moveIntoStack(_sourceType.sizeOnStack());
        utils.convertType(_sourceType, *m_dataType, true);
        if (!_move)
        {
            utils.moveToStackTop(m_dataType->sizeOnStack());
            utils.copyToStackTop(1 + m_dataType->sizeOnStack(), m_dataType->sizeOnStack());
        }
        if (!m_padded)
        {
            solAssert(m_dataType->calldataEncodedSize(false) == 1, "Invalid non-padded type.");
            if (m_dataType->category() == Type::Category::FixedBytes)
                m_context << u256(0) << Instruction::BYTE;
            m_context << Instruction::SWAP1 << Instruction::MSTORE8;
        }
        else
        {
            utils.storeInMemoryDynamic(*m_dataType, m_padded);
            m_context << Instruction::POP;
        }
    }
    else
    {
        solAssert(_sourceType == *m_dataType, "Conversion not implemented for assignment to memory.");

        solAssert(m_dataType->sizeOnStack() == 1, "");
        if (!_move)
            m_context << Instruction::DUP2 << Instruction::SWAP1;
        // stack: [value] value lvalue
        // only store the reference
        m_context << Instruction::MSTORE;
    }
}

void MemoryItem::setToZero(SourceLocation const&, bool _removeReference) const
{
    CompilerUtils utils(m_context);
    if (!_removeReference)
        m_context << Instruction::DUP1;
    utils.pushZeroValue(*m_dataType);
    utils.storeInMemoryDynamic(*m_dataType, m_padded);
    m_context << Instruction::POP;
}

StorageItem::StorageItem(CompilerContext& _compilerContext, VariableDeclaration const& _declaration):
    StorageItem(_compilerContext, *_declaration.annotation().type)
{
    auto const& location = m_context.storageLocationOfVariable(_declaration);
    m_context << location.first << u256(location.second);
}

StorageItem::StorageItem(CompilerContext& _compilerContext, Type const& _type):
    LValue(_compilerContext, &_type)
{
    if (m_dataType->isValueType())
    {
        solAssert(m_dataType->storageSize() == m_dataType->sizeOnStack(), "");
        solAssert(m_dataType->storageSize() == 1, "Invalid storage size.");
    }
}

void StorageItem::retrieveValue(SourceLocation const&, bool _remove) const
{
    // stack: storage_key storage_offset
    if (!m_dataType->isValueType())
    {
        solAssert(m_dataType->sizeOnStack() == 1, "Invalid storage ref size.");
        if (_remove)
            m_context << Instruction::POP; // remove byte offset
        else
            m_context << Instruction::DUP2;
        return;
    }
    if (!_remove)
        CompilerUtils(m_context).copyToStackTop(sizeOnStack(), sizeOnStack());
    if (m_dataType->storageBytes() == 32)
        m_context << Instruction::POP << Instruction::SLOAD;
    else
    {
        m_context
            << Instruction::SWAP1 << Instruction::SLOAD << Instruction::SWAP1
            << u256(0x100) << Instruction::EXP << Instruction::SWAP1 << Instruction::DIV;
        if (m_dataType->category() == Type::Category::FixedBytes)
            m_context << (u256(0x1) << (256 - 8 * m_dataType->storageBytes())) << Instruction::MUL;
        else if (
            m_dataType->category() == Type::Category::Integer &&
            dynamic_cast<IntegerType const&>(*m_dataType).isSigned()
        )
            m_context << u256(m_dataType->storageBytes() - 1) << Instruction::SIGNEXTEND;
        else
            m_context << ((u256(0x1) << (8 * m_dataType->storageBytes())) - 1) << Instruction::AND;
    }
}

void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _location, bool _move) const
{
    CompilerUtils utils(m_context);
    // stack: value storage_key storage_offset
    if (m_dataType->isValueType())
    {
        solAssert(m_dataType->storageBytes() <= 32, "Invalid storage bytes size.");
        solAssert(m_dataType->storageBytes() > 0, "Invalid storage bytes size.");
        if (m_dataType->storageBytes() == 32)
        {
            // offset should be zero
            m_context << Instruction::POP;
            if (!_move)
                m_context << Instruction::DUP2 << Instruction::SWAP1;
            m_context << Instruction::SSTORE;
        }
        else
        {
            // OR the value into the other values in the storage slot
            m_context << u256(0x100) << Instruction::EXP;
            // stack: value storage_ref multiplier
            // fetch old value
            m_context << Instruction::DUP2 << Instruction::SLOAD;
            // stack: value storege_ref multiplier old_full_value
            // clear bytes in old value
            m_context
                << Instruction::DUP2 << ((u256(1) << (8 * m_dataType->storageBytes())) - 1)
                << Instruction::MUL;
            m_context << Instruction::NOT << Instruction::AND;
            // stack: value storage_ref multiplier cleared_value
            m_context
                << Instruction::SWAP1 << Instruction::DUP4;
            // stack: value storage_ref cleared_value multiplier value
            if (m_dataType->category() == Type::Category::FixedBytes)
                m_context
                    << (u256(0x1) << (256 - 8 * dynamic_cast<FixedBytesType const&>(*m_dataType).numBytes()))
                    << Instruction::SWAP1 << Instruction::DIV;
            else if (
                m_dataType->category() == Type::Category::Integer &&
                dynamic_cast<IntegerType const&>(*m_dataType).isSigned()
            )
                // remove the higher order bits
                m_context
                    << (u256(1) << (8 * (32 - m_dataType->storageBytes())))
                    << Instruction::SWAP1
                    << Instruction::DUP2
                    << Instruction::MUL
                    << Instruction::DIV;
            m_context  << Instruction::MUL << Instruction::OR;
            // stack: value storage_ref updated_value
            m_context << Instruction::SWAP1 << Instruction::SSTORE;
            if (_move)
                m_context << Instruction::POP;
        }
    }
    else
    {
        solAssert(
            _sourceType.category() == m_dataType->category(),
            "Wrong type conversation for assignment.");
        if (m_dataType->category() == Type::Category::Array)
        {
            m_context << Instruction::POP; // remove byte offset
            ArrayUtils(m_context).copyArrayToStorage(
                dynamic_cast<ArrayType const&>(*m_dataType),
                dynamic_cast<ArrayType const&>(_sourceType)
            );
            if (_move)
                m_context << Instruction::POP;
        }
        else if (m_dataType->category() == Type::Category::Struct)
        {
            // stack layout: source_ref target_ref target_offset
            // note that we have structs, so offset should be zero and are ignored
            m_context << Instruction::POP;
            auto const& structType = dynamic_cast<StructType const&>(*m_dataType);
            auto const& sourceType = dynamic_cast<StructType const&>(_sourceType);
            solAssert(
                structType.structDefinition() == sourceType.structDefinition(),
                "Struct assignment with conversion."
            );
            solAssert(sourceType.location() != DataLocation::CallData, "Structs in calldata not supported.");
            for (auto const& member: structType.members(nullptr))
            {
                // assign each member that is not a mapping
                TypePointer const& memberType = member.type;
                if (memberType->category() == Type::Category::Mapping)
                    continue;
                TypePointer sourceMemberType = sourceType.memberType(member.name);
                if (sourceType.location() == DataLocation::Storage)
                {
                    // stack layout: source_ref target_ref
                    pair<u256, unsigned> const& offsets = sourceType.storageOffsetsOfMember(member.name);
                    m_context << offsets.first << Instruction::DUP3 << Instruction::ADD;
                    m_context << u256(offsets.second);
                    // stack: source_ref target_ref source_member_ref source_member_off
                    StorageItem(m_context, *sourceMemberType).retrieveValue(_location, true);
                    // stack: source_ref target_ref source_value...
                }
                else
                {
                    solAssert(sourceType.location() == DataLocation::Memory, "");
                    // stack layout: source_ref target_ref
                    TypePointer sourceMemberType = sourceType.memberType(member.name);
                    m_context << sourceType.memoryOffsetOfMember(member.name);
                    m_context << Instruction::DUP3 << Instruction::ADD;
                    MemoryItem(m_context, *sourceMemberType).retrieveValue(_location, true);
                    // stack layout: source_ref target_ref source_value...
                }
                unsigned stackSize = sourceMemberType->sizeOnStack();
                pair<u256, unsigned> const& offsets = structType.storageOffsetsOfMember(member.name);
                m_context << dupInstruction(1 + stackSize) << offsets.first << Instruction::ADD;
                m_context << u256(offsets.second);
                // stack: source_ref target_ref target_off source_value... target_member_ref target_member_byte_off
                StorageItem(m_context, *memberType).storeValue(*sourceMemberType, _location, true);
            }
            // stack layout: source_ref target_ref
            solAssert(sourceType.sizeOnStack() == 1, "Unexpected source size.");
            if (_move)
                utils.popStackSlots(2);
            else
                m_context << Instruction::SWAP1 << 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->category() == Type::Category::Array)
    {
        if (!_removeReference)
            CompilerUtils(m_context).copyToStackTop(sizeOnStack(), sizeOnStack());
        ArrayUtils(m_context).clearArray(dynamic_cast<ArrayType const&>(*m_dataType));
    }
    else if (m_dataType->category() == Type::Category::Struct)
    {
        // stack layout: storage_key storage_offset
        // @todo this can be improved: use StorageItem for non-value types, and just store 0 in
        // all slots that contain value types later.
        auto const& structType = dynamic_cast<StructType const&>(*m_dataType);
        for (auto const& member: structType.members(nullptr))
        {
            // zero each member that is not a mapping
            TypePointer const& memberType = member.type;
            if (memberType->category() == Type::Category::Mapping)
                continue;
            pair<u256, unsigned> const& offsets = structType.storageOffsetsOfMember(member.name);
            m_context
                << offsets.first << Instruction::DUP3 << Instruction::ADD
                << u256(offsets.second);
            StorageItem(m_context, *memberType).setToZero();
        }
        if (_removeReference)
            m_context << Instruction::POP << Instruction::POP;
    }
    else
    {
        solAssert(m_dataType->isValueType(), "Clearing of unsupported type requested: " + m_dataType->toString());
        if (!_removeReference)
            CompilerUtils(m_context).copyToStackTop(sizeOnStack(), sizeOnStack());
        if (m_dataType->storageBytes() == 32)
        {
            // offset should be zero
            m_context
                << Instruction::POP << u256(0)
                << Instruction::SWAP1 << Instruction::SSTORE;
        }
        else
        {
            m_context << u256(0x100) << Instruction::EXP;
            // stack: storage_ref multiplier
            // fetch old value
            m_context << Instruction::DUP2 << Instruction::SLOAD;
            // stack: storege_ref multiplier old_full_value
            // clear bytes in old value
            m_context
                << Instruction::SWAP1 << ((u256(1) << (8 * m_dataType->storageBytes())) - 1)
                << Instruction::MUL;
            m_context << Instruction::NOT << Instruction::AND;
            // stack: storage_ref cleared_value
            m_context << Instruction::SWAP1 << Instruction::SSTORE;
        }
    }
}

/// Used in StorageByteArrayElement
static FixedBytesType byteType(1);

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

void StorageByteArrayElement::retrieveValue(SourceLocation const&, bool _remove) const
{
    // stack: ref byte_number
    if (_remove)
        m_context << Instruction::SWAP1 << Instruction::SLOAD
            << Instruction::SWAP1 << Instruction::BYTE;
    else
        m_context << Instruction::DUP2 << Instruction::SLOAD
            << Instruction::DUP2 << Instruction::BYTE;
    m_context << (u256(1) << (256 - 8)) << Instruction::MUL;
}

void StorageByteArrayElement::storeValue(Type const&, SourceLocation const&, bool _move) const
{
    // stack: value ref byte_number
    m_context << u256(31) << Instruction::SUB << u256(0x100) << Instruction::EXP;
    // stack: value ref (1<<(8*(31-byte_number)))
    m_context << Instruction::DUP2 << Instruction::SLOAD;
    // stack: value ref (1<<(8*(31-byte_number))) old_full_value
    // clear byte in old value
    m_context << Instruction::DUP2 << u256(0xff) << Instruction::MUL
        << Instruction::NOT << Instruction::AND;
    // stack: value ref (1<<(32-byte_number)) old_full_value_with_cleared_byte
    m_context << Instruction::SWAP1;
    m_context << (u256(1) << (256 - 8)) << Instruction::DUP5 << Instruction::DIV
        << Instruction::MUL << Instruction::OR;
    // stack: value ref new_full_value
    m_context << Instruction::SWAP1 << Instruction::SSTORE;
    if (_move)
        m_context << Instruction::POP;
}

void StorageByteArrayElement::setToZero(SourceLocation const&, bool _removeReference) const
{
    // stack: ref byte_number
    if (!_removeReference)
        m_context << Instruction::DUP2 << Instruction::DUP2;
    m_context << u256(31) << Instruction::SUB << u256(0x100) << Instruction::EXP;
    // stack: ref (1<<(8*(31-byte_number)))
    m_context << Instruction::DUP2 << Instruction::SLOAD;
    // stack: ref (1<<(8*(31-byte_number))) old_full_value
    // clear byte in old value
    m_context << Instruction::SWAP1 << u256(0xff) << Instruction::MUL;
    m_context << Instruction::NOT << Instruction::AND;
    // stack: ref old_full_value_with_cleared_byte
    m_context << Instruction::SWAP1 << Instruction::SSTORE;
}

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

void StorageArrayLength::retrieveValue(SourceLocation const&, bool _remove) const
{
    ArrayUtils(m_context).retrieveLength(m_arrayType);
    if (_remove)
        m_context << Instruction::SWAP1 << Instruction::POP;
}

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

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


TupleObject::TupleObject(
    CompilerContext& _compilerContext,
    std::vector<std::unique_ptr<LValue>>&& _lvalues
):
    LValue(_compilerContext), m_lvalues(move(_lvalues))
{
}

unsigned TupleObject::sizeOnStack() const
{
    unsigned size = 0;
    for (auto const& lv: m_lvalues)
        if (lv)
            size += lv->sizeOnStack();
    return size;
}

void TupleObject::retrieveValue(SourceLocation const& _location, bool _remove) const
{
    unsigned initialDepth = sizeOnStack();
    unsigned initialStack = m_context.stackHeight();
    for (auto const& lv: m_lvalues)
        if (lv)
        {
            solAssert(initialDepth + m_context.stackHeight() >= initialStack, "");
            unsigned depth = initialDepth + m_context.stackHeight() - initialStack;
            if (lv->sizeOnStack() > 0)
            {
                if (_remove && depth > lv->sizeOnStack())
                    CompilerUtils(m_context).moveToStackTop(depth, depth - lv->sizeOnStack());
                else if (!_remove && depth > 0)
                    CompilerUtils(m_context).copyToStackTop(depth, lv->sizeOnStack());
            }
            lv->retrieveValue(_location, true);
        }
}

void TupleObject::storeValue(Type const& _sourceType, SourceLocation const& _location, bool) const
{
    // values are below the lvalue references
    unsigned valuePos = sizeOnStack();
    TypePointers const& valueTypes = dynamic_cast<TupleType const&>(_sourceType).components();
    solAssert(valueTypes.size() == m_lvalues.size(), "");
    // valuePos .... refPos ...
    // We will assign from right to left to optimize stack layout.
    for (size_t i = 0; i < m_lvalues.size(); ++i)
    {
        unique_ptr<LValue> const& lvalue = m_lvalues[m_lvalues.size() - i - 1];
        TypePointer const& valType = valueTypes[valueTypes.size() - i - 1];
        unsigned stackHeight = m_context.stackHeight();
        solAssert(!valType == !lvalue, "");
        if (!lvalue)
            continue;
        valuePos += valType->sizeOnStack();
        // copy value to top
        CompilerUtils(m_context).copyToStackTop(valuePos, valType->sizeOnStack());
        // move lvalue ref above value
        CompilerUtils(m_context).moveToStackTop(valType->sizeOnStack(), lvalue->sizeOnStack());
        lvalue->storeValue(*valType, _location, true);
        valuePos += m_context.stackHeight() - stackHeight;
    }
    // As the type of an assignment to a tuple type is the empty tuple, we always move.
    CompilerUtils(m_context).popStackElement(_sourceType);
}

void TupleObject::setToZero(SourceLocation const& _location, bool _removeReference) const
{
    if (_removeReference)
    {
        for (size_t i = 0; i < m_lvalues.size(); ++i)
            if (m_lvalues[m_lvalues.size() - i])
                m_lvalues[m_lvalues.size() - i]->setToZero(_location, true);
    }
    else
    {
        unsigned depth = sizeOnStack();
        for (auto const& val: m_lvalues)
            if (val)
            {
                if (val->sizeOnStack() > 0)
                    CompilerUtils(m_context).copyToStackTop(depth, val->sizeOnStack());
                val->setToZero(_location, false);
                depth -= val->sizeOnStack();
            }
    }
}