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/*
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, Type const& _type, bool _padToWordBoundaries)
{
solAssert(_type.getCategory() != Type::Category::ByteArray, "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::ByteArray)
{
auto const& type = dynamic_cast<ByteArrayType const&>(_type);
if (type.getLocation() == ByteArrayType::Location::CallData)
{
m_context << eth::Instruction::CALLDATASIZE << u256(0) << eth::Instruction::DUP3
<< eth::Instruction::CALLDATACOPY
<< eth::Instruction::CALLDATASIZE << eth::Instruction::ADD;
}
else
{
solAssert(type.getLocation() == ByteArrayType::Location::Storage, "Memory byte arrays not yet implemented.");
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)
{
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();
// 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;
}
void CompilerUtils::computeHashStatic(Type const& _type, bool _padToWordBoundaries)
{
unsigned length = storeInMemory(0, _type, _padToWordBoundaries);
m_context << u256(length) << u256(0) << eth::Instruction::SHA3;
}
void CompilerUtils::copyByteArrayToStorage(ByteArrayType const& _targetType,
ByteArrayType const& _sourceType) const
{
// stack layout: [source_ref] target_ref (top)
// need to leave target_ref on the stack at the end
solAssert(_targetType.getLocation() == ByteArrayType::Location::Storage, "");
switch (_sourceType.getLocation())
{
case ByteArrayType::Location::CallData:
{
// @todo this does not take length into account. It also assumes that after "CALLDATALENGTH" we only have zeros.
// fetch old length and convert to words
m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD;
m_context << u256(31) << eth::Instruction::ADD
<< u256(32) << eth::Instruction::SWAP1 << eth::Instruction::DIV;
// stack here: target_ref target_length_words
// actual array data is stored at SHA3(storage_offset)
m_context << eth::Instruction::DUP2;
CompilerUtils(m_context).computeHashStatic();
// compute target_data_end
m_context << eth::Instruction::DUP1 << eth::Instruction::SWAP2 << eth::Instruction::ADD
<< eth::Instruction::SWAP1;
// stack here: target_ref target_data_end target_data_ref
// store length (in bytes)
m_context << eth::Instruction::CALLDATASIZE;
m_context << eth::Instruction::DUP1 << eth::Instruction::DUP5 << eth::Instruction::SSTORE;
// jump to end if length is zero
m_context << eth::Instruction::ISZERO;
eth::AssemblyItem copyLoopEnd = m_context.newTag();
m_context.appendConditionalJumpTo(copyLoopEnd);
// store start offset
m_context << u256(0);
// stack now: target_ref target_data_end target_data_ref calldata_offset
eth::AssemblyItem copyLoopStart = m_context.newTag();
m_context << copyLoopStart
// copy from calldata and store
<< eth::Instruction::DUP1 << eth::Instruction::CALLDATALOAD
<< eth::Instruction::DUP3 << eth::Instruction::SSTORE
// increment target_data_ref by 1
<< eth::Instruction::SWAP1 << u256(1) << eth::Instruction::ADD
// increment calldata_offset by 32
<< eth::Instruction::SWAP1 << u256(32) << eth::Instruction::ADD
// check for loop condition
<< eth::Instruction::DUP1 << eth::Instruction::CALLDATASIZE << eth::Instruction::GT;
m_context.appendConditionalJumpTo(copyLoopStart);
m_context << eth::Instruction::POP;
m_context << copyLoopEnd;
// now clear leftover bytes of the old value
// stack now: target_ref target_data_end target_data_ref
clearStorageLoop();
m_context << eth::Instruction::POP;
break;
}
case ByteArrayType::Location::Storage:
{
// this copies source to target and also clears target if it was larger
// stack: source_ref target_ref
// store target_ref
m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2;
// fetch lengthes
m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD << eth::Instruction::SWAP2
<< eth::Instruction::DUP1 << eth::Instruction::SLOAD;
// stack: target_ref target_len_bytes target_ref source_ref source_len_bytes
// store new target length
m_context << eth::Instruction::DUP1 << eth::Instruction::DUP4 << eth::Instruction::SSTORE;
// compute hashes (data positions)
m_context << eth::Instruction::SWAP2;
CompilerUtils(m_context).computeHashStatic();
m_context << eth::Instruction::SWAP1;
CompilerUtils(m_context).computeHashStatic();
// stack: target_ref target_len_bytes source_len_bytes target_data_pos source_data_pos
// convert lengthes from bytes to storage slots
m_context << u256(31) << u256(32) << eth::Instruction::DUP1 << eth::Instruction::DUP3
<< eth::Instruction::DUP8 << eth::Instruction::ADD << eth::Instruction::DIV
<< eth::Instruction::SWAP2
<< eth::Instruction::DUP6 << eth::Instruction::ADD << eth::Instruction::DIV;
// stack: target_ref target_len_bytes source_len_bytes target_data_pos source_data_pos target_len source_len
// @todo we might be able to go without a third counter
m_context << u256(0);
// stack: target_ref target_len_bytes source_len_bytes target_data_pos source_data_pos target_len source_len counter
eth::AssemblyItem copyLoopStart = m_context.newTag();
m_context << copyLoopStart;
// check for loop condition
m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3
<< eth::Instruction::GT << eth::Instruction::ISZERO;
eth::AssemblyItem copyLoopEnd = m_context.newTag();
m_context.appendConditionalJumpTo(copyLoopEnd);
// copy
m_context << eth::Instruction::DUP4 << eth::Instruction::DUP2 << eth::Instruction::ADD
<< eth::Instruction::SLOAD
<< eth::Instruction::DUP6 << eth::Instruction::DUP3 << eth::Instruction::ADD
<< eth::Instruction::SSTORE;
// increment
m_context << u256(1) << eth::Instruction::ADD;
m_context.appendJumpTo(copyLoopStart);
m_context << copyLoopEnd;
// zero-out leftovers in target
// stack: target_ref target_len_bytes source_len_bytes target_data_pos source_data_pos target_len source_len counter
// add counter to target_data_pos
m_context << eth::Instruction::DUP5 << eth::Instruction::ADD
<< eth::Instruction::SWAP5 << eth::Instruction::POP;
// stack: target_ref target_len_bytes target_data_pos_updated target_data_pos source_data_pos target_len source_len
// add length to target_data_pos to get target_data_end
m_context << eth::Instruction::POP << eth::Instruction::DUP3 << eth::Instruction::ADD
<< eth::Instruction::SWAP4
<< eth::Instruction::POP << eth::Instruction::POP << eth::Instruction::POP;
// stack: target_ref target_data_end target_data_pos_updated
clearStorageLoop();
m_context << eth::Instruction::POP;
break;
}
default:
solAssert(false, "Given byte array location not implemented.");
}
}
void CompilerUtils::clearByteArray(ByteArrayType const& _type) const
{
solAssert(_type.getLocation() == ByteArrayType::Location::Storage, "");
// fetch length
m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD;
// set length to zero
m_context << u256(0) << eth::Instruction::DUP3 << eth::Instruction::SSTORE;
// convert length from bytes to storage slots
m_context << u256(31) << eth::Instruction::ADD
<< u256(32) << eth::Instruction::SWAP1 << eth::Instruction::DIV;
// compute data positions
m_context << eth::Instruction::SWAP1;
CompilerUtils(m_context).computeHashStatic();
// stack: len data_pos
m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2 << eth::Instruction::ADD
<< eth::Instruction::SWAP1;
clearStorageLoop();
// cleanup
m_context << eth::Instruction::POP;
}
unsigned CompilerUtils::prepareMemoryStore(Type const& _type, bool _padToWordBoundaries) const
{
unsigned _encodedSize = _type.getCalldataEncodedSize();
unsigned numBytes = _padToWordBoundaries ? getPaddedSize(_encodedSize) : _encodedSize;
bool leftAligned = _type.getCategory() == Type::Category::String;
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;
}
void CompilerUtils::clearStorageLoop() const
{
// stack: end_pos pos
eth::AssemblyItem loopStart = m_context.newTag();
m_context << loopStart;
// check for loop condition
m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3
<< eth::Instruction::GT << eth::Instruction::ISZERO;
eth::AssemblyItem zeroLoopEnd = m_context.newTag();
m_context.appendConditionalJumpTo(zeroLoopEnd);
// zero out
m_context << u256(0) << eth::Instruction::DUP2 << eth::Instruction::SSTORE;
// increment
m_context << u256(1) << eth::Instruction::ADD;
m_context.appendJumpTo(loopStart);
// cleanup
m_context << zeroLoopEnd;
m_context << eth::Instruction::POP;
}
}
}
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