mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
67 lines
2.6 KiB
C
67 lines
2.6 KiB
C
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/*
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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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* Optimisation stage that assigns memory offsets to variables that would become unreachable if
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* assigned a stack slot as usual and replaces references and assignments to them by mload and mstore calls.
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*/
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#pragma once
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#include <libyul/optimiser/OptimiserStep.h>
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namespace solidity::yul
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{
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struct Object;
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/**
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* Optimisation stage that assigns memory offsets to variables that would become unreachable if
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* assigned a stack slot as usual.
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*
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* Uses CompilabilityChecker to determine which variables in which functions are unreachable.
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*
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* Only variables outside of functions contained in cycles in the call graph are considered. Thereby it is possible
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* to assign globally fixed memory offsets to the variable. If a variable in a function contained in a cycle in the
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* call graph is reported as unreachable, the process is aborted.
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*
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* Offsets are assigned to the variables, s.t. on every path through the call graph each variable gets a unique offset
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* in memory. However, distinct paths through the call graph can use the same memory offsets for their variables.
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*
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* The current arguments to the ``memoryguard`` calls are used as base memory offset and then replaced by the offset past
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* the last memory offset used for a variable on any path through the call graph.
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*
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* Finally, the StackToMemoryMover is called to actually move the variables to their offsets in memory.
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*
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* Prerequisite: Disambiguator
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*/
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class StackLimitEvader
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{
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public:
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/// @a _unreachableVariables can be determined by the CompilabilityChecker.
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/// Can only be run on the EVM dialect with objects.
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/// Abort and do nothing, if no ``memoryguard`` call or several ``memoryguard`` calls
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/// with non-matching arguments are found, or if any of the @a _unreachableVariables
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/// are contained in a recursive function.
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static void run(
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OptimiserStepContext& _context,
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Object& _object,
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std::map<YulString, std::set<YulString>> const& _unreachableVariables
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);
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};
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}
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