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/*
This file is part of solidity.
solidity 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.
solidity 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 solidity. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* Assembly interface for EVM and EVM1.5.
*/
#include <libyul/backends/evm/EVMAssembly.h>
#include <libevmasm/Instruction.h>
#include <liblangutil/Exceptions.h>
using namespace std;
using namespace dev;
using namespace langutil;
using namespace yul;
namespace
{
/// Size of labels in bytes. Four-byte labels are required by some EVM1.5 instructions.
size_t constexpr labelReferenceSize = 4;
size_t constexpr assemblySizeReferenceSize = 4;
}
void EVMAssembly::setSourceLocation(SourceLocation const&)
{
// Ignored for now;
}
void EVMAssembly::appendInstruction(solidity::Instruction _instr)
{
m_bytecode.push_back(uint8_t(_instr));
m_stackHeight += solidity::instructionInfo(_instr).ret - solidity::instructionInfo(_instr).args;
}
void EVMAssembly::appendConstant(u256 const& _constant)
{
bytes data = toCompactBigEndian(_constant, 1);
appendInstruction(solidity::pushInstruction(data.size()));
m_bytecode += data;
}
void EVMAssembly::appendLabel(LabelID _labelId)
{
setLabelToCurrentPosition(_labelId);
appendInstruction(solidity::Instruction::JUMPDEST);
}
void EVMAssembly::appendLabelReference(LabelID _labelId)
{
solAssert(!m_evm15, "Cannot use plain label references in EMV1.5 mode.");
// @TODO we now always use labelReferenceSize for all labels, it could be shortened
// for some of them.
appendInstruction(solidity::pushInstruction(labelReferenceSize));
m_labelReferences[m_bytecode.size()] = _labelId;
m_bytecode += bytes(labelReferenceSize);
}
EVMAssembly::LabelID EVMAssembly::newLabelId()
{
m_labelPositions[m_nextLabelId] = size_t(-1);
return m_nextLabelId++;
}
AbstractAssembly::LabelID EVMAssembly::namedLabel(string const& _name)
{
solAssert(!_name.empty(), "");
if (!m_namedLabels.count(_name))
m_namedLabels[_name] = newLabelId();
return m_namedLabels[_name];
}
void EVMAssembly::appendLinkerSymbol(string const&)
{
solAssert(false, "Linker symbols not yet implemented.");
}
void EVMAssembly::appendJump(int _stackDiffAfter)
{
solAssert(!m_evm15, "Plain JUMP used for EVM 1.5");
appendInstruction(solidity::Instruction::JUMP);
m_stackHeight += _stackDiffAfter;
}
void EVMAssembly::appendJumpTo(LabelID _labelId, int _stackDiffAfter)
{
if (m_evm15)
{
m_bytecode.push_back(uint8_t(solidity::Instruction::JUMPTO));
appendLabelReferenceInternal(_labelId);
m_stackHeight += _stackDiffAfter;
}
else
{
appendLabelReference(_labelId);
appendJump(_stackDiffAfter);
}
}
void EVMAssembly::appendJumpToIf(LabelID _labelId)
{
if (m_evm15)
{
m_bytecode.push_back(uint8_t(solidity::Instruction::JUMPIF));
appendLabelReferenceInternal(_labelId);
m_stackHeight--;
}
else
{
appendLabelReference(_labelId);
appendInstruction(solidity::Instruction::JUMPI);
}
}
void EVMAssembly::appendBeginsub(LabelID _labelId, int _arguments)
{
solAssert(m_evm15, "BEGINSUB used for EVM 1.0");
solAssert(_arguments >= 0, "");
setLabelToCurrentPosition(_labelId);
m_bytecode.push_back(uint8_t(solidity::Instruction::BEGINSUB));
m_stackHeight += _arguments;
}
void EVMAssembly::appendJumpsub(LabelID _labelId, int _arguments, int _returns)
{
solAssert(m_evm15, "JUMPSUB used for EVM 1.0");
solAssert(_arguments >= 0 && _returns >= 0, "");
m_bytecode.push_back(uint8_t(solidity::Instruction::JUMPSUB));
appendLabelReferenceInternal(_labelId);
m_stackHeight += _returns - _arguments;
}
void EVMAssembly::appendReturnsub(int _returns, int _stackDiffAfter)
{
solAssert(m_evm15, "RETURNSUB used for EVM 1.0");
solAssert(_returns >= 0, "");
m_bytecode.push_back(uint8_t(solidity::Instruction::RETURNSUB));
m_stackHeight += _stackDiffAfter - _returns;
}
eth::LinkerObject EVMAssembly::finalize()
{
size_t bytecodeSize = m_bytecode.size();
for (auto const& ref: m_assemblySizePositions)
updateReference(ref, assemblySizeReferenceSize, u256(bytecodeSize));
for (auto const& ref: m_labelReferences)
{
size_t referencePos = ref.first;
solAssert(m_labelPositions.count(ref.second), "");
size_t labelPos = m_labelPositions.at(ref.second);
solAssert(labelPos != size_t(-1), "Undefined but allocated label used.");
updateReference(referencePos, labelReferenceSize, u256(labelPos));
}
eth::LinkerObject obj;
obj.bytecode = m_bytecode;
return obj;
}
void EVMAssembly::setLabelToCurrentPosition(LabelID _labelId)
{
solAssert(m_labelPositions.count(_labelId), "Label not found.");
solAssert(m_labelPositions[_labelId] == size_t(-1), "Label already set.");
m_labelPositions[_labelId] = m_bytecode.size();
}
void EVMAssembly::appendLabelReferenceInternal(LabelID _labelId)
{
m_labelReferences[m_bytecode.size()] = _labelId;
m_bytecode += bytes(labelReferenceSize);
}
void EVMAssembly::appendAssemblySize()
{
appendInstruction(solidity::pushInstruction(assemblySizeReferenceSize));
m_assemblySizePositions.push_back(m_bytecode.size());
m_bytecode += bytes(assemblySizeReferenceSize);
}
void EVMAssembly::updateReference(size_t pos, size_t size, u256 value)
{
solAssert(m_bytecode.size() >= size && pos <= m_bytecode.size() - size, "");
solAssert(value < (u256(1) << (8 * size)), "");
for (size_t i = 0; i < size; i++)
m_bytecode[pos + i] = uint8_t((value >> (8 * (size - i - 1))) & 0xff);
}
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