mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
127 lines
3.6 KiB
C++
127 lines
3.6 KiB
C++
/*
|
|
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/>.
|
|
*/
|
|
/**
|
|
* @file BlockDeduplicator.cpp
|
|
* @author Christian <c@ethdev.com>
|
|
* @date 2015
|
|
* Unifies basic blocks that share content.
|
|
*/
|
|
|
|
#include <libevmasm/BlockDeduplicator.h>
|
|
#include <functional>
|
|
#include <libevmasm/AssemblyItem.h>
|
|
#include <libevmasm/SemanticInformation.h>
|
|
|
|
using namespace std;
|
|
using namespace dev;
|
|
using namespace dev::eth;
|
|
|
|
|
|
bool BlockDeduplicator::deduplicate()
|
|
{
|
|
// Compares indices based on the suffix that starts there, ignoring tags and stopping at
|
|
// opcodes that stop the control flow.
|
|
|
|
// Virtual tag that signifies "the current block" and which is used to optimise loops.
|
|
// We abort if this virtual tag actually exists.
|
|
AssemblyItem pushSelf(PushTag, u256(-4));
|
|
if (
|
|
std::count(m_items.cbegin(), m_items.cend(), pushSelf.tag()) ||
|
|
std::count(m_items.cbegin(), m_items.cend(), pushSelf.pushTag())
|
|
)
|
|
return false;
|
|
|
|
function<bool(size_t, size_t)> comparator = [&](size_t _i, size_t _j)
|
|
{
|
|
if (_i == _j)
|
|
return false;
|
|
|
|
// To compare recursive loops, we have to already unify PushTag opcodes of the
|
|
// block's own tag.
|
|
AssemblyItem pushFirstTag(pushSelf);
|
|
AssemblyItem pushSecondTag(pushSelf);
|
|
|
|
if (_i < m_items.size() && m_items.at(_i).type() == Tag)
|
|
pushFirstTag = m_items.at(_i).pushTag();
|
|
if (_j < m_items.size() && m_items.at(_j).type() == Tag)
|
|
pushSecondTag = m_items.at(_j).pushTag();
|
|
|
|
BlockIterator first(m_items.begin() + _i, m_items.end(), &pushFirstTag, &pushSelf);
|
|
BlockIterator second(m_items.begin() + _j, m_items.end(), &pushSecondTag, &pushSelf);
|
|
BlockIterator end(m_items.end(), m_items.end());
|
|
|
|
if (first != end && (*first).type() == Tag)
|
|
++first;
|
|
if (second != end && (*second).type() == Tag)
|
|
++second;
|
|
|
|
return std::lexicographical_compare(first, end, second, end);
|
|
};
|
|
|
|
size_t iterations = 0;
|
|
for (; ; ++iterations)
|
|
{
|
|
//@todo this should probably be optimized.
|
|
set<size_t, function<bool(size_t, size_t)>> blocksSeen(comparator);
|
|
map<u256, u256> tagReplacement;
|
|
for (size_t i = 0; i < m_items.size(); ++i)
|
|
{
|
|
if (m_items.at(i).type() != Tag)
|
|
continue;
|
|
auto it = blocksSeen.find(i);
|
|
if (it == blocksSeen.end())
|
|
blocksSeen.insert(i);
|
|
else
|
|
tagReplacement[m_items.at(i).data()] = m_items.at(*it).data();
|
|
}
|
|
|
|
bool changed = false;
|
|
for (AssemblyItem& item: m_items)
|
|
if (item.type() == PushTag && tagReplacement.count(item.data()))
|
|
{
|
|
changed = true;
|
|
item.setData(tagReplacement.at(item.data()));
|
|
}
|
|
if (!changed)
|
|
break;
|
|
}
|
|
return iterations > 0;
|
|
}
|
|
|
|
BlockDeduplicator::BlockIterator& BlockDeduplicator::BlockIterator::operator++()
|
|
{
|
|
if (it == end)
|
|
return *this;
|
|
if (SemanticInformation::altersControlFlow(*it) && *it != AssemblyItem(Instruction::JUMPI))
|
|
it = end;
|
|
else
|
|
{
|
|
++it;
|
|
while (it != end && it->type() == Tag)
|
|
++it;
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
AssemblyItem const& BlockDeduplicator::BlockIterator::operator*() const
|
|
{
|
|
if (replaceItem && replaceWith && *it == *replaceItem)
|
|
return *replaceWith;
|
|
else
|
|
return *it;
|
|
}
|