mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
110 lines
3.3 KiB
C++
110 lines
3.3 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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// SPDX-License-Identifier: GPL-3.0
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/**
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* Optimiser component that calculates hash values for blocks.
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*/
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#pragma once
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#include <libyul/optimiser/ASTWalker.h>
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#include <libyul/ASTForward.h>
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#include <libyul/YulString.h>
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namespace solidity::yul
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{
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/**
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* Optimiser component that calculates hash values for blocks.
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* Syntactically equal blocks will have identical hashes and
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* blocks with equal hashes will likely be syntactically equal.
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*
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* The names of internally declared variables are replaced by
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* a simple counter, so differing names are not taken into account,
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* but only the order of references to declared variables.
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*
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* Similarly, the names of referenced external variables are not considered,
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* but replaced by a (distinct) counter as well.
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*
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* Prerequisite: Disambiguator, ForLoopInitRewriter
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*/
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class BlockHasher: public ASTWalker
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{
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public:
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using ASTWalker::operator();
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void operator()(Literal const&) override;
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void operator()(Identifier const&) override;
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void operator()(FunctionCall const& _funCall) override;
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void operator()(ExpressionStatement const& _statement) override;
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void operator()(Assignment const& _assignment) override;
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void operator()(VariableDeclaration const& _varDecl) override;
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void operator()(If const& _if) override;
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void operator()(Switch const& _switch) override;
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void operator()(FunctionDefinition const&) override;
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void operator()(ForLoop const&) override;
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void operator()(Break const&) override;
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void operator()(Continue const&) override;
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void operator()(Leave const&) override;
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void operator()(Block const& _block) override;
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static std::map<Block const*, uint64_t> run(Block const& _block);
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static constexpr uint64_t fnvPrime = 1099511628211u;
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static constexpr uint64_t fnvEmptyHash = 14695981039346656037u;
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private:
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BlockHasher(std::map<Block const*, uint64_t>& _blockHashes): m_blockHashes(_blockHashes) {}
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void hash8(uint8_t _value)
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{
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m_hash *= fnvPrime;
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m_hash ^= _value;
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}
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void hash16(uint16_t _value)
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{
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hash8(static_cast<uint8_t>(_value & 0xFF));
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hash8(static_cast<uint8_t>(_value >> 8));
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}
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void hash32(uint32_t _value)
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{
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hash16(static_cast<uint16_t>(_value & 0xFFFF));
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hash16(static_cast<uint16_t>(_value >> 16));
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}
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void hash64(uint64_t _value)
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{
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hash32(static_cast<uint32_t>(_value & 0xFFFFFFFF));
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hash32(static_cast<uint32_t>(_value >> 32));
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}
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std::map<Block const*, uint64_t>& m_blockHashes;
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uint64_t m_hash = fnvEmptyHash;
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struct VariableReference
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{
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size_t id = 0;
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bool isExternal = false;
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};
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std::map<YulString, VariableReference> m_variableReferences;
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std::vector<YulString> m_externalReferences;
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size_t m_externalIdentifierCount = 0;
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size_t m_internalIdentifierCount = 0;
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};
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}
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