mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
69 lines
1.9 KiB
C++
69 lines
1.9 KiB
C++
/*
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This file is part of solidity.
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solidity 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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solidity 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 solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @author Alex Beregszaszi
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* Removes unused JUMPDESTs.
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*/
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#include "JumpdestRemover.h"
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#include <libsolidity/interface/Exceptions.h>
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#include <libevmasm/AssemblyItem.h>
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using namespace std;
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using namespace dev::eth;
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using namespace dev;
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bool JumpdestRemover::optimise(set<size_t> const& _tagsReferencedFromOutside)
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{
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set<size_t> references{referencedTags(m_items, -1)};
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references.insert(_tagsReferencedFromOutside.begin(), _tagsReferencedFromOutside.end());
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size_t initialSize = m_items.size();
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/// Remove tags which are never referenced.
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auto pend = remove_if(
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m_items.begin(),
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m_items.end(),
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[&](AssemblyItem const& _item)
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{
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if (_item.type() != Tag)
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return false;
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auto asmIdAndTag = _item.splitForeignPushTag();
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solAssert(asmIdAndTag.first == size_t(-1), "Sub-assembly tag used as label.");
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size_t tag = asmIdAndTag.second;
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return !references.count(tag);
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}
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);
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m_items.erase(pend, m_items.end());
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return m_items.size() != initialSize;
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}
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set<size_t> JumpdestRemover::referencedTags(AssemblyItems const& _items, size_t _subId)
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{
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set<size_t> ret;
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for (auto const& item: _items)
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if (item.type() == PushTag)
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{
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auto subAndTag = item.splitForeignPushTag();
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if (subAndTag.first == _subId)
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ret.insert(subAndTag.second);
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}
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return ret;
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}
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