mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
164 lines
5.1 KiB
C++
164 lines
5.1 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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* Specific AST walkers that collect semantical facts.
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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/SideEffects.h>
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#include <set>
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namespace yul
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{
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struct Dialect;
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/**
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* Specific AST walker that determines side-effect free-ness and movability of code.
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* Enters into function definitions.
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*/
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class SideEffectsCollector: public ASTWalker
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{
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public:
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explicit SideEffectsCollector(Dialect const& _dialect): m_dialect(_dialect) {}
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SideEffectsCollector(Dialect const& _dialect, Expression const& _expression);
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SideEffectsCollector(Dialect const& _dialect, Statement const& _statement);
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SideEffectsCollector(Dialect const& _dialect, Block const& _ast);
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using ASTWalker::operator();
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void operator()(FunctionalInstruction const& _functionalInstruction) override;
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void operator()(FunctionCall const& _functionCall) override;
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bool movable() const { return m_sideEffects.movable; }
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bool sideEffectFree(bool _allowMSizeModification = false) const
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{
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if (_allowMSizeModification)
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return sideEffectFreeIfNoMSize();
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else
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return m_sideEffects.sideEffectFree;
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}
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bool sideEffectFreeIfNoMSize() const { return m_sideEffects.sideEffectFreeIfNoMSize; }
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bool invalidatesStorage() const { return m_sideEffects.invalidatesStorage; }
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bool invalidatesMemory() const { return m_sideEffects.invalidatesMemory; }
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private:
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Dialect const& m_dialect;
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SideEffects m_sideEffects;
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};
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/**
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* This class can be used to determine the side-effects of user-defined functions.
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*
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* It is given a dialect and a mapping that represents the direct calls from user-defined
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* functions to other user-defined functions and built-in functions.
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*/
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class SideEffectsPropagator
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{
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public:
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static std::map<YulString, SideEffects> sideEffects(
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Dialect const& _dialect,
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std::map<YulString, std::set<YulString>> const& _directCallGraph
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);
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};
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/**
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* Class that can be used to find out if certain code contains the MSize instruction.
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*
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* Note that this is a purely syntactic property meaning that even if this is false,
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* the code can still contain calls to functions that contain the msize instruction.
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*
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* The only safe way to determine this is by passing the full AST.
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*/
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class MSizeFinder: public ASTWalker
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{
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public:
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static bool containsMSize(Dialect const& _dialect, Block const& _ast);
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using ASTWalker::operator();
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void operator()(FunctionalInstruction const& _instr);
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void operator()(FunctionCall const& _funCall);
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private:
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MSizeFinder(Dialect const& _dialect): m_dialect(_dialect) {}
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Dialect const& m_dialect;
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bool m_msizeFound = false;
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};
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/**
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* Specific AST walker that determines whether an expression is movable
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* and collects the referenced variables.
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* Can only be used on expressions.
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*/
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class MovableChecker: public SideEffectsCollector
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{
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public:
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explicit MovableChecker(Dialect const& _dialect): SideEffectsCollector(_dialect) {}
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MovableChecker(Dialect const& _dialect, Expression const& _expression);
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void operator()(Identifier const& _identifier) override;
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/// Disallow visiting anything apart from Expressions (this throws).
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void visit(Statement const&) override;
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using ASTWalker::visit;
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std::set<YulString> const& referencedVariables() const { return m_variableReferences; }
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private:
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/// Which variables the current expression references.
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std::set<YulString> m_variableReferences;
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};
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/**
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* Helper class to find "irregular" control flow.
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* This includes termination, break and continue.
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*/
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class TerminationFinder
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{
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public:
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enum class ControlFlow { FlowOut, Break, Continue, Terminate };
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TerminationFinder(Dialect const& _dialect): m_dialect(_dialect) {}
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/// @returns the index of the first statement in the provided sequence
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/// that is an unconditional ``break``, ``continue`` or a
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/// call to a terminating builtin function.
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/// If control flow can continue at the end of the list,
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/// returns `FlowOut` and ``size_t(-1)``.
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/// The function might return ``FlowOut`` even though control
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/// flow cannot actually continue.
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std::pair<ControlFlow, size_t> firstUnconditionalControlFlowChange(
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std::vector<Statement> const& _statements
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);
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/// @returns the control flow type of the given statement.
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/// This function could return FlowOut even if control flow never continues.
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ControlFlow controlFlowKind(Statement const& _statement);
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/// @returns true if the expression statement is a direct
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/// call to a builtin terminating function like
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/// ``stop``, ``revert`` or ``return``.
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bool isTerminatingBuiltin(ExpressionStatement const& _exprStmnt);
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private:
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Dialect const& m_dialect;
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};
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}
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