mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
move libevmasm
This commit is contained in:
Dimitry
@@ -0,0 +1,411 @@
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/*
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This file is part of cpp-ethereum.
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cpp-ethereum is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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cpp-ethereum is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file KnownState.cpp
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* @author Christian <c@ethdev.com>
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* @date 2015
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* Contains knowledge about the state of the virtual machine at a specific instruction.
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*/
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#include "KnownState.h"
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#include <functional>
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#include <libdevcore/SHA3.h>
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#include <libevmasm/AssemblyItem.h>
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using namespace std;
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using namespace dev;
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using namespace dev::eth;
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ostream& KnownState::stream(ostream& _out) const
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{
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auto streamExpressionClass = [this](ostream& _out, Id _id)
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{
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auto const& expr = m_expressionClasses->representative(_id);
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_out << " " << dec << _id << ": ";
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if (!expr.item)
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_out << " no item";
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else if (expr.item->type() == UndefinedItem)
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_out << " unknown " << int(expr.item->data());
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else
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_out << *expr.item;
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if (expr.sequenceNumber)
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_out << "@" << dec << expr.sequenceNumber;
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_out << "(";
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for (Id arg: expr.arguments)
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_out << dec << arg << ",";
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_out << ")" << endl;
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};
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_out << "=== State ===" << endl;
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_out << "Stack height: " << dec << m_stackHeight << endl;
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_out << "Equivalence classes: " << endl;
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for (Id eqClass = 0; eqClass < m_expressionClasses->size(); ++eqClass)
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streamExpressionClass(_out, eqClass);
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_out << "Stack: " << endl;
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for (auto const& it: m_stackElements)
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{
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_out << " " << dec << it.first << ": ";
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streamExpressionClass(_out, it.second);
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}
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_out << "Storage: " << endl;
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for (auto const& it: m_storageContent)
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{
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_out << " ";
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streamExpressionClass(_out, it.first);
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_out << ": ";
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streamExpressionClass(_out, it.second);
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}
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_out << "Memory: " << endl;
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for (auto const& it: m_memoryContent)
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{
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_out << " ";
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streamExpressionClass(_out, it.first);
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_out << ": ";
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streamExpressionClass(_out, it.second);
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}
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return _out;
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}
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KnownState::StoreOperation KnownState::feedItem(AssemblyItem const& _item, bool _copyItem)
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{
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StoreOperation op;
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if (_item.type() == Tag)
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{
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// can be ignored
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}
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else if (_item.type() != Operation)
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{
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assertThrow(_item.deposit() == 1, InvalidDeposit, "");
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if (_item.pushedValue())
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// only available after assembly stage, should not be used for optimisation
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setStackElement(++m_stackHeight, m_expressionClasses->find(*_item.pushedValue()));
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else
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setStackElement(++m_stackHeight, m_expressionClasses->find(_item, {}, _copyItem));
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}
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else
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{
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Instruction instruction = _item.instruction();
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InstructionInfo info = instructionInfo(instruction);
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if (SemanticInformation::isDupInstruction(_item))
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setStackElement(
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m_stackHeight + 1,
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stackElement(
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m_stackHeight - int(instruction) + int(Instruction::DUP1),
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_item.location()
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)
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);
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else if (SemanticInformation::isSwapInstruction(_item))
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swapStackElements(
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m_stackHeight,
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m_stackHeight - 1 - int(instruction) + int(Instruction::SWAP1),
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_item.location()
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);
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else if (instruction != Instruction::POP)
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{
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vector<Id> arguments(info.args);
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for (int i = 0; i < info.args; ++i)
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arguments[i] = stackElement(m_stackHeight - i, _item.location());
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if (_item.instruction() == Instruction::SSTORE)
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op = storeInStorage(arguments[0], arguments[1], _item.location());
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else if (_item.instruction() == Instruction::SLOAD)
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setStackElement(
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m_stackHeight + _item.deposit(),
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loadFromStorage(arguments[0], _item.location())
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);
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else if (_item.instruction() == Instruction::MSTORE)
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op = storeInMemory(arguments[0], arguments[1], _item.location());
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else if (_item.instruction() == Instruction::MLOAD)
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setStackElement(
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m_stackHeight + _item.deposit(),
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loadFromMemory(arguments[0], _item.location())
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);
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else if (_item.instruction() == Instruction::SHA3)
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setStackElement(
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m_stackHeight + _item.deposit(),
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applySha3(arguments.at(0), arguments.at(1), _item.location())
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);
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else
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{
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bool invMem = SemanticInformation::invalidatesMemory(_item.instruction());
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bool invStor = SemanticInformation::invalidatesStorage(_item.instruction());
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// We could be a bit more fine-grained here (CALL only invalidates part of
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// memory, etc), but we do not for now.
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if (invMem)
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resetMemory();
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if (invStor)
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resetStorage();
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if (invMem || invStor)
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m_sequenceNumber += 2; // Increment by two because it can read and write
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assertThrow(info.ret <= 1, InvalidDeposit, "");
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if (info.ret == 1)
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setStackElement(
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m_stackHeight + _item.deposit(),
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m_expressionClasses->find(_item, arguments, _copyItem)
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);
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}
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}
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m_stackElements.erase(
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m_stackElements.upper_bound(m_stackHeight + _item.deposit()),
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m_stackElements.end()
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);
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m_stackHeight += _item.deposit();
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}
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return op;
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}
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/// Helper function for KnownState::reduceToCommonKnowledge, removes everything from
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/// _this which is not in or not equal to the value in _other.
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template <class _Mapping> void intersect(_Mapping& _this, _Mapping const& _other)
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{
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for (auto it = _this.begin(); it != _this.end();)
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if (_other.count(it->first) && _other.at(it->first) == it->second)
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++it;
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else
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it = _this.erase(it);
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}
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void KnownState::reduceToCommonKnowledge(KnownState const& _other, bool _combineSequenceNumbers)
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{
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int stackDiff = m_stackHeight - _other.m_stackHeight;
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for (auto it = m_stackElements.begin(); it != m_stackElements.end();)
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if (_other.m_stackElements.count(it->first - stackDiff))
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{
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Id other = _other.m_stackElements.at(it->first - stackDiff);
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if (it->second == other)
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++it;
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else
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{
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set<u256> theseTags = tagsInExpression(it->second);
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set<u256> otherTags = tagsInExpression(other);
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if (!theseTags.empty() && !otherTags.empty())
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{
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theseTags.insert(otherTags.begin(), otherTags.end());
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it->second = tagUnion(theseTags);
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++it;
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}
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else
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it = m_stackElements.erase(it);
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}
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}
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else
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it = m_stackElements.erase(it);
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// Use the smaller stack height. Essential to terminate in case of loops.
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if (m_stackHeight > _other.m_stackHeight)
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{
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map<int, Id> shiftedStack;
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for (auto const& stackElement: m_stackElements)
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shiftedStack[stackElement.first - stackDiff] = stackElement.second;
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m_stackElements = move(shiftedStack);
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m_stackHeight = _other.m_stackHeight;
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}
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intersect(m_storageContent, _other.m_storageContent);
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intersect(m_memoryContent, _other.m_memoryContent);
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if (_combineSequenceNumbers)
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m_sequenceNumber = max(m_sequenceNumber, _other.m_sequenceNumber);
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}
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bool KnownState::operator==(KnownState const& _other) const
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{
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if (m_storageContent != _other.m_storageContent || m_memoryContent != _other.m_memoryContent)
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return false;
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int stackDiff = m_stackHeight - _other.m_stackHeight;
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auto thisIt = m_stackElements.cbegin();
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auto otherIt = _other.m_stackElements.cbegin();
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for (; thisIt != m_stackElements.cend() && otherIt != _other.m_stackElements.cend(); ++thisIt, ++otherIt)
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if (thisIt->first - stackDiff != otherIt->first || thisIt->second != otherIt->second)
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return false;
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return (thisIt == m_stackElements.cend() && otherIt == _other.m_stackElements.cend());
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}
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ExpressionClasses::Id KnownState::stackElement(int _stackHeight, SourceLocation const& _location)
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{
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if (m_stackElements.count(_stackHeight))
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return m_stackElements.at(_stackHeight);
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// Stack element not found (not assigned yet), create new unknown equivalence class.
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return m_stackElements[_stackHeight] =
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m_expressionClasses->find(AssemblyItem(UndefinedItem, _stackHeight, _location));
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}
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KnownState::Id KnownState::relativeStackElement(int _stackOffset, SourceLocation const& _location)
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{
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return stackElement(m_stackHeight + _stackOffset, _location);
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}
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void KnownState::clearTagUnions()
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{
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for (auto it = m_stackElements.begin(); it != m_stackElements.end();)
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if (m_tagUnions.left.count(it->second))
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it = m_stackElements.erase(it);
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else
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++it;
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}
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void KnownState::setStackElement(int _stackHeight, Id _class)
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{
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m_stackElements[_stackHeight] = _class;
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}
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void KnownState::swapStackElements(
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int _stackHeightA,
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int _stackHeightB,
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SourceLocation const& _location
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)
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{
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assertThrow(_stackHeightA != _stackHeightB, OptimizerException, "Swap on same stack elements.");
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// ensure they are created
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stackElement(_stackHeightA, _location);
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stackElement(_stackHeightB, _location);
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swap(m_stackElements[_stackHeightA], m_stackElements[_stackHeightB]);
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}
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KnownState::StoreOperation KnownState::storeInStorage(
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Id _slot,
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Id _value,
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SourceLocation const& _location)
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{
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if (m_storageContent.count(_slot) && m_storageContent[_slot] == _value)
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// do not execute the storage if we know that the value is already there
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return StoreOperation();
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m_sequenceNumber++;
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decltype(m_storageContent) storageContents;
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// Copy over all values (i.e. retain knowledge about them) where we know that this store
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// operation will not destroy the knowledge. Specifically, we copy storage locations we know
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// are different from _slot or locations where we know that the stored value is equal to _value.
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for (auto const& storageItem: m_storageContent)
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if (m_expressionClasses->knownToBeDifferent(storageItem.first, _slot) || storageItem.second == _value)
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storageContents.insert(storageItem);
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m_storageContent = move(storageContents);
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AssemblyItem item(Instruction::SSTORE, _location);
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Id id = m_expressionClasses->find(item, {_slot, _value}, true, m_sequenceNumber);
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StoreOperation operation(StoreOperation::Storage, _slot, m_sequenceNumber, id);
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m_storageContent[_slot] = _value;
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// increment a second time so that we get unique sequence numbers for writes
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m_sequenceNumber++;
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return operation;
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}
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ExpressionClasses::Id KnownState::loadFromStorage(Id _slot, SourceLocation const& _location)
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{
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if (m_storageContent.count(_slot))
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return m_storageContent.at(_slot);
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AssemblyItem item(Instruction::SLOAD, _location);
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return m_storageContent[_slot] = m_expressionClasses->find(item, {_slot}, true, m_sequenceNumber);
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}
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KnownState::StoreOperation KnownState::storeInMemory(Id _slot, Id _value, SourceLocation const& _location)
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{
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if (m_memoryContent.count(_slot) && m_memoryContent[_slot] == _value)
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// do not execute the store if we know that the value is already there
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return StoreOperation();
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m_sequenceNumber++;
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decltype(m_memoryContent) memoryContents;
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// copy over values at points where we know that they are different from _slot by at least 32
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for (auto const& memoryItem: m_memoryContent)
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if (m_expressionClasses->knownToBeDifferentBy32(memoryItem.first, _slot))
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memoryContents.insert(memoryItem);
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m_memoryContent = move(memoryContents);
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AssemblyItem item(Instruction::MSTORE, _location);
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Id id = m_expressionClasses->find(item, {_slot, _value}, true, m_sequenceNumber);
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StoreOperation operation(StoreOperation(StoreOperation::Memory, _slot, m_sequenceNumber, id));
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m_memoryContent[_slot] = _value;
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// increment a second time so that we get unique sequence numbers for writes
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m_sequenceNumber++;
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return operation;
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}
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ExpressionClasses::Id KnownState::loadFromMemory(Id _slot, SourceLocation const& _location)
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{
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if (m_memoryContent.count(_slot))
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return m_memoryContent.at(_slot);
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AssemblyItem item(Instruction::MLOAD, _location);
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return m_memoryContent[_slot] = m_expressionClasses->find(item, {_slot}, true, m_sequenceNumber);
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}
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KnownState::Id KnownState::applySha3(
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Id _start,
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Id _length,
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SourceLocation const& _location
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)
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{
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AssemblyItem sha3Item(Instruction::SHA3, _location);
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// Special logic if length is a short constant, otherwise we cannot tell.
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u256 const* l = m_expressionClasses->knownConstant(_length);
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// unknown or too large length
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if (!l || *l > 128)
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return m_expressionClasses->find(sha3Item, {_start, _length}, true, m_sequenceNumber);
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vector<Id> arguments;
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for (u256 i = 0; i < *l; i += 32)
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{
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Id slot = m_expressionClasses->find(
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AssemblyItem(Instruction::ADD, _location),
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{_start, m_expressionClasses->find(i)}
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);
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arguments.push_back(loadFromMemory(slot, _location));
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}
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if (m_knownSha3Hashes.count(arguments))
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return m_knownSha3Hashes.at(arguments);
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Id v;
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// If all arguments are known constants, compute the sha3 here
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if (all_of(arguments.begin(), arguments.end(), [this](Id _a) { return !!m_expressionClasses->knownConstant(_a); }))
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{
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bytes data;
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for (Id a: arguments)
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data += toBigEndian(*m_expressionClasses->knownConstant(a));
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data.resize(size_t(*l));
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v = m_expressionClasses->find(AssemblyItem(u256(sha3(data)), _location));
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}
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else
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v = m_expressionClasses->find(sha3Item, {_start, _length}, true, m_sequenceNumber);
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return m_knownSha3Hashes[arguments] = v;
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}
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set<u256> KnownState::tagsInExpression(KnownState::Id _expressionId)
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{
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if (m_tagUnions.left.count(_expressionId))
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return m_tagUnions.left.at(_expressionId);
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// Might be a tag, then return the set of itself.
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ExpressionClasses::Expression expr = m_expressionClasses->representative(_expressionId);
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if (expr.item && expr.item->type() == PushTag)
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return set<u256>({expr.item->data()});
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else
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return set<u256>();
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}
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KnownState::Id KnownState::tagUnion(set<u256> _tags)
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{
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if (m_tagUnions.right.count(_tags))
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return m_tagUnions.right.at(_tags);
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else
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{
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Id id = m_expressionClasses->newClass(SourceLocation());
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m_tagUnions.right.insert(make_pair(_tags, id));
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return id;
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}
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}
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