diff options
author | Christian Parpart <christian@ethereum.org> | 2018-10-15 17:52:35 +0800 |
---|---|---|
committer | Christian Parpart <christian@ethereum.org> | 2018-10-15 17:52:35 +0800 |
commit | 9a4bec7e474a310c7f93ff3b84928e0e9ba9cce6 (patch) | |
tree | 2668ab22a40aad2448081f7bf22c7235d4b4c963 /libyul/optimiser/ExpressionSplitter.h | |
parent | b965fd6e17f77e94afeb070a27182251b85b8ab3 (diff) | |
download | dexon-solidity-9a4bec7e474a310c7f93ff3b84928e0e9ba9cce6.tar dexon-solidity-9a4bec7e474a310c7f93ff3b84928e0e9ba9cce6.tar.gz dexon-solidity-9a4bec7e474a310c7f93ff3b84928e0e9ba9cce6.tar.bz2 dexon-solidity-9a4bec7e474a310c7f93ff3b84928e0e9ba9cce6.tar.lz dexon-solidity-9a4bec7e474a310c7f93ff3b84928e0e9ba9cce6.tar.xz dexon-solidity-9a4bec7e474a310c7f93ff3b84928e0e9ba9cce6.tar.zst dexon-solidity-9a4bec7e474a310c7f93ff3b84928e0e9ba9cce6.zip |
Renaming libjulia to libyul
Diffstat (limited to 'libyul/optimiser/ExpressionSplitter.h')
-rw-r--r-- | libyul/optimiser/ExpressionSplitter.h | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/libyul/optimiser/ExpressionSplitter.h b/libyul/optimiser/ExpressionSplitter.h new file mode 100644 index 00000000..89757df3 --- /dev/null +++ b/libyul/optimiser/ExpressionSplitter.h @@ -0,0 +1,86 @@ +/* + This file is part of solidity. + + solidity is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + solidity is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with solidity. If not, see <http://www.gnu.org/licenses/>. +*/ +/** + * Optimiser component that turns complex expressions into multiple variable + * declarations. + */ +#pragma once + +#include <libyul/ASTDataForward.h> + +#include <libyul/optimiser/ASTWalker.h> +#include <libyul/optimiser/NameDispenser.h> + +#include <vector> + +namespace dev +{ +namespace julia +{ + +class NameCollector; + + +/** + * Optimiser component that modifies an AST in place, turning complex + * expressions into simple expressions and multiple variable declarations. + * + * Code of the form + * + * sstore(mul(x, 4), mload(y)) + * + * is transformed into + * + * let a1 := mload(y) + * let a2 := mul(x, 4) + * sstore(a2, a1) + * + * The transformation is not applied to loop conditions, because the loop control flow + * does not allow "outlining" the inner expressions in all cases. + * + * The final program should be in a form such that with the exception of a loop condition, + * function calls can only appear in the right-hand side of a variable declaration, + * assignments or expression statements and all arguments have to be constants or variables. + */ +class ExpressionSplitter: public ASTModifier +{ +public: + explicit ExpressionSplitter(NameDispenser& _nameDispenser): + m_nameDispenser(_nameDispenser) + { } + + virtual void operator()(FunctionalInstruction&) override; + virtual void operator()(FunctionCall&) override; + virtual void operator()(If&) override; + virtual void operator()(Switch&) override; + virtual void operator()(ForLoop&) override; + virtual void operator()(Block& _block) override; + +private: + /// Replaces the expression by a variable if it is a function call or functional + /// instruction. The declaration of the variable is appended to m_statementsToPrefix. + /// Recurses via visit(). + void outlineExpression(Expression& _expr); + + /// List of statements that should go in front of the currently visited AST element, + /// at the statement level. + std::vector<Statement> m_statementsToPrefix; + NameDispenser& m_nameDispenser; +}; + +} +} |