solidity/libyul/backends/evm/EVMAssembly.cpp

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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/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
* Assembly interface for EVM and EVM1.5.
*/
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#include <libyul/backends/evm/EVMAssembly.h>
#include <libyul/Exceptions.h>
#include <libevmasm/Instruction.h>
using namespace std;
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using namespace solidity;
using namespace solidity::yul;
using namespace solidity::util;
using namespace solidity::langutil;
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;
}
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void EVMAssembly::appendInstruction(evmasm::Instruction _instr)
{
m_bytecode.push_back(uint8_t(_instr));
m_stackHeight += instructionInfo(_instr).ret - instructionInfo(_instr).args;
}
void EVMAssembly::appendConstant(u256 const& _constant)
{
bytes data = toCompactBigEndian(_constant, 1);
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appendInstruction(evmasm::pushInstruction(static_cast<unsigned>(data.size())));
m_bytecode += data;
}
void EVMAssembly::appendLabel(LabelID _labelId)
{
setLabelToCurrentPosition(_labelId);
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appendInstruction(evmasm::Instruction::JUMPDEST);
}
void EVMAssembly::appendLabelReference(LabelID _labelId)
{
// @TODO we now always use labelReferenceSize for all labels, it could be shortened
// for some of them.
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appendInstruction(evmasm::pushInstruction(labelReferenceSize));
m_labelReferences[m_bytecode.size()] = _labelId;
m_bytecode += bytes(labelReferenceSize);
}
EVMAssembly::LabelID EVMAssembly::newLabelId()
{
m_labelPositions[m_nextLabelId] = numeric_limits<size_t>::max();
return m_nextLabelId++;
}
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AbstractAssembly::LabelID EVMAssembly::namedLabel(string const& _name)
{
yulAssert(!_name.empty(), "");
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if (!m_namedLabels.count(_name))
m_namedLabels[_name] = newLabelId();
return m_namedLabels[_name];
}
void EVMAssembly::appendLinkerSymbol(string const&)
{
yulAssert(false, "Linker symbols not yet implemented.");
}
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void EVMAssembly::appendJump(int _stackDiffAfter, JumpType)
{
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appendInstruction(evmasm::Instruction::JUMP);
m_stackHeight += _stackDiffAfter;
}
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void EVMAssembly::appendJumpTo(LabelID _labelId, int _stackDiffAfter, JumpType _jumpType)
{
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appendLabelReference(_labelId);
appendJump(_stackDiffAfter, _jumpType);
}
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void EVMAssembly::appendJumpToIf(LabelID _labelId, JumpType)
{
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appendLabelReference(_labelId);
appendInstruction(evmasm::Instruction::JUMPI);
}
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evmasm::LinkerObject EVMAssembly::finalize()
{
yulAssert(!m_invalid, "Attempted to finalize invalid assembly object.");
size_t bytecodeSize = m_bytecode.size();
for (auto const& ref: m_assemblySizePositions)
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updateReference(ref, assemblySizeReferenceSize, u256(bytecodeSize));
for (auto const& ref: m_labelReferences)
{
size_t referencePos = ref.first;
yulAssert(m_labelPositions.count(ref.second), "");
size_t labelPos = m_labelPositions.at(ref.second);
yulAssert(labelPos != numeric_limits<size_t>::max(), "Undefined but allocated label used.");
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updateReference(referencePos, labelReferenceSize, u256(labelPos));
}
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evmasm::LinkerObject obj;
obj.bytecode = m_bytecode;
return obj;
}
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void EVMAssembly::setLabelToCurrentPosition(LabelID _labelId)
{
yulAssert(m_labelPositions.count(_labelId), "Label not found.");
yulAssert(m_labelPositions[_labelId] == numeric_limits<size_t>::max(), "Label already set.");
m_labelPositions[_labelId] = m_bytecode.size();
}
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void EVMAssembly::appendLabelReferenceInternal(LabelID _labelId)
{
m_labelReferences[m_bytecode.size()] = _labelId;
m_bytecode += bytes(labelReferenceSize);
}
void EVMAssembly::appendAssemblySize()
{
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appendInstruction(evmasm::pushInstruction(assemblySizeReferenceSize));
m_assemblySizePositions.push_back(m_bytecode.size());
m_bytecode += bytes(assemblySizeReferenceSize);
}
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pair<shared_ptr<AbstractAssembly>, AbstractAssembly::SubID> EVMAssembly::createSubAssembly(string)
{
yulAssert(false, "Sub assemblies not implemented.");
return {};
}
void EVMAssembly::appendDataOffset(vector<AbstractAssembly::SubID> const&)
{
yulAssert(false, "Data not implemented.");
}
void EVMAssembly::appendDataSize(vector<AbstractAssembly::SubID> const&)
{
yulAssert(false, "Data not implemented.");
}
AbstractAssembly::SubID EVMAssembly::appendData(bytes const&)
{
yulAssert(false, "Data not implemented.");
}
void EVMAssembly::appendImmutable(std::string const&)
{
yulAssert(false, "loadimmutable not implemented.");
}
void EVMAssembly::appendImmutableAssignment(std::string const&)
{
yulAssert(false, "setimmutable not implemented.");
}
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void EVMAssembly::updateReference(size_t pos, size_t size, u256 value)
{
yulAssert(m_bytecode.size() >= size && pos <= m_bytecode.size() - size, "");
yulAssert(value < (u256(1) << (8 * size)), "");
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for (size_t i = 0; i < size; i++)
m_bytecode[pos + i] = uint8_t((value >> (8 * (size - i - 1))) & 0xff);
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}