mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
114 lines
3.9 KiB
C++
114 lines
3.9 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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// SPDX-License-Identifier: GPL-3.0
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#pragma once
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#include <libyul/optimiser/ASTWalker.h>
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#include <libyul/optimiser/NameDispenser.h>
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#include <libyul/optimiser/OptimiserStep.h>
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#include <libyul/ASTForward.h>
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#include <libyul/Dialect.h>
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#include <map>
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#include <optional>
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#include <vector>
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namespace solidity::yul
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{
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/**
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* FunctionSpecializer: Optimiser step that specializes the function with its literal arguments.
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*
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* If a function, say, `function f(a, b) { sstore (a, b)}`, is called with literal arguments, for
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* example, `f(x, 5)`, where `x` is an identifier, it could be specialized by creating a new
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* function `f_1` that takes only one argument, i.e.,
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*
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* function f_1(a_1) {
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* let b_1 := 5
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* sstore(a_1, b_1)
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* }
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*
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* Other optimization steps will be able to make more simplifications to the function. The
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* optimization step is mainly useful for functions that would not be inlined.
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*
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* Prerequisites: Disambiguator, FunctionHoister
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*
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* LiteralRematerialiser is recommended as a prerequisite, even though it's not required for
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* correctness.
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*/
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class FunctionSpecializer: public ASTModifier
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{
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public:
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/// A vector of function-call arguments. An element 'has value' if it's a literal, and the
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/// corresponding Expression would be the literal.
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using LiteralArguments = std::vector<std::optional<Expression>>;
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static constexpr char const* name{"FunctionSpecializer"};
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static void run(OptimiserStepContext& _context, Block& _ast);
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using ASTModifier::operator();
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void operator()(FunctionCall& _f) override;
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private:
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explicit FunctionSpecializer(
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std::set<YulString> _recursiveFunctions,
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NameDispenser& _nameDispenser,
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Dialect const& _dialect
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):
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m_recursiveFunctions(std::move(_recursiveFunctions)),
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m_nameDispenser(_nameDispenser),
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m_dialect(_dialect)
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{}
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/// Returns a vector of Expressions, where the index `i` is an expression if the function's
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/// `i`-th argument can be specialized, nullopt otherwise.
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LiteralArguments specializableArguments(FunctionCall const& _f);
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/// Given a function definition `_f` and its arguments `_arguments`, of which, at least one is a
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/// literal, this function returns a new function with the literal arguments specialized.
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///
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/// Note that the returned function definition will have new (and unique) names, for both the
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/// function and variable declarations to retain the properties enforced by the Disambiguator.
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///
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/// For example, if `_f` is the function `function f(a, b, c) -> d { sstore(a, b) }`,
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/// `_arguments` is the vector of literals `{1, 2, nullopt}` and the @param, `_newName` has
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/// value `f_1`, the returned function could be:
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///
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/// function f_1(c_2) -> d_3 {
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/// let a_4 := 1
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/// let b_5 := 2
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/// sstore(a_4, b_5)
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/// }
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///
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FunctionDefinition specialize(
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FunctionDefinition const& _f,
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YulString _newName,
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FunctionSpecializer::LiteralArguments _arguments
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);
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/// A mapping between the old function name and a pair of new function name and its arguments.
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/// Note that at least one of the argument will have a literal value.
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std::map<YulString, std::vector<std::pair<YulString, LiteralArguments>>> m_oldToNewMap;
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/// We skip specializing recursive functions. Need backtracking to properly deal with them.
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std::set<YulString> const m_recursiveFunctions;
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NameDispenser& m_nameDispenser;
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Dialect const& m_dialect;
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};
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}
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