mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
79 lines
2.5 KiB
C++
79 lines
2.5 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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#pragma once
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#include <set>
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namespace yul
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{
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/**
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* Side effects of code.
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*
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* The default-constructed value applies to the "empty code".
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*/
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struct SideEffects
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{
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/// If true, expressions in this code can be freely moved and copied without altering the
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/// semantics.
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/// At statement level, it means that functions containing this code can be
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/// called multiple times, their calls can be rearranged and calls can also be
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/// deleted without changing the semantics.
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/// This means it cannot depend on storage or memory, cannot have any side-effects,
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/// but it can depend on state that is constant across an EVM-call.
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bool movable = true;
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/// If true, the code can be removed without changing the semantics.
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bool sideEffectFree = true;
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/// If true, the code can be removed without changing the semantics as long as
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/// the whole program does not contain the msize instruction.
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bool sideEffectFreeIfNoMSize = true;
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/// If false, storage is guaranteed to be unchanged by the code under all
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/// circumstances.
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bool invalidatesStorage = false;
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/// If false, memory is guaranteed to be unchanged by the code under all
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/// circumstances.
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bool invalidatesMemory = false;
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/// @returns the worst-case side effects.
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static SideEffects worst()
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{
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return SideEffects{false, false, false, true, true};
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}
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/// @returns the combined side effects of two pieces of code.
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SideEffects operator+(SideEffects const& _other)
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{
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return SideEffects{
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movable && _other.movable,
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sideEffectFree && _other.sideEffectFree,
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sideEffectFreeIfNoMSize && _other.sideEffectFreeIfNoMSize,
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invalidatesStorage || _other.invalidatesStorage,
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invalidatesMemory || _other.invalidatesMemory
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};
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}
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/// Adds the side effects of another piece of code to this side effect.
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SideEffects& operator+=(SideEffects const& _other)
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{
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*this = *this + _other;
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return *this;
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}
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};
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}
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