mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
Refactor data flow analysis out of remat.
This commit is contained in:
chriseth
parent
e100af592b
commit
2b6a7665ee
195
libjulia/optimiser/DataFlowAnalyzer.cpp
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195
libjulia/optimiser/DataFlowAnalyzer.cpp
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@ -0,0 +1,195 @@
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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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* Base class to perform data flaw analysis during AST walks.
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* Tracks assignments and is used as base class for both Rematerialiser and
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* Common Subexpression Eliminator.
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*/
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#include <libjulia/optimiser/DataFlowAnalyzer.h>
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#include <libjulia/optimiser/NameCollector.h>
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#include <libsolidity/inlineasm/AsmData.h>
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#include <libjulia/optimiser/Semantics.h>
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#include <libdevcore/CommonData.h>
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#include <boost/range/adaptor/reversed.hpp>
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using namespace std;
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using namespace dev;
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using namespace dev::julia;
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void DataFlowAnalyzer::operator()(Assignment& _assignment)
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{
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set<string> names;
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for (auto const& var: _assignment.variableNames)
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names.insert(var.name);
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solAssert(_assignment.value, "");
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visit(*_assignment.value);
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handleAssignment(names, _assignment.value.get());
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}
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void DataFlowAnalyzer::operator()(VariableDeclaration& _varDecl)
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{
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set<string> names;
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for (auto const& var: _varDecl.variables)
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names.insert(var.name);
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m_variableScopes.back().first += names;
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if (_varDecl.value)
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visit(*_varDecl.value);
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handleAssignment(names, _varDecl.value.get());
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}
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void DataFlowAnalyzer::operator()(If& _if)
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{
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ASTModifier::operator()(_if);
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Assignments assignments;
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assignments(_if.body);
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clearValues(assignments.names());
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}
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void DataFlowAnalyzer::operator()(Switch& _switch)
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{
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visit(*_switch.expression);
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set<string> assignedVariables;
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for (auto& _case: _switch.cases)
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{
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(*this)(_case.body);
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Assignments assignments;
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assignments(_case.body);
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assignedVariables += assignments.names();
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// This is a little too destructive, we could retain the old values.
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clearValues(assignments.names());
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}
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clearValues(assignedVariables);
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}
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void DataFlowAnalyzer::operator()(FunctionDefinition& _fun)
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{
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m_variableScopes.push_back(make_pair(set<string>(), true));
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for (auto const& parameter: _fun.parameters)
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m_variableScopes.back().first.insert(parameter.name);
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for (auto const& var: _fun.returnVariables)
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m_variableScopes.back().first.insert(var.name);
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ASTModifier::operator()(_fun);
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m_variableScopes.pop_back();
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}
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void DataFlowAnalyzer::operator()(ForLoop& _for)
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{
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// Special scope handling of the pre block.
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m_variableScopes.push_back(make_pair(set<string>(), false));
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for (auto& statement: _for.pre.statements)
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visit(statement);
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Assignments assignments;
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assignments(_for.body);
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assignments(_for.post);
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clearValues(assignments.names());
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visit(*_for.condition);
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(*this)(_for.body);
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(*this)(_for.post);
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clearValues(assignments.names());
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m_variableScopes.pop_back();
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}
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void DataFlowAnalyzer::operator()(Block& _block)
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{
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size_t numScopes = m_variableScopes.size();
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m_variableScopes.push_back(make_pair(set<string>(), false));
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ASTModifier::operator()(_block);
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m_variableScopes.pop_back();
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solAssert(numScopes == m_variableScopes.size(), "");
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}
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void DataFlowAnalyzer::handleAssignment(set<string> const& _variables, Expression* _value)
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{
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clearValues(_variables);
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MovableChecker movableChecker;
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if (_value)
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movableChecker.visit(*_value);
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if (_variables.size() == 1)
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{
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string const& name = *_variables.begin();
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// Expression has to be movable and cannot contain a reference
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// to the variable that will be assigned to.
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// TODO: Add a test for that
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if (_value && movableChecker.movable() && !movableChecker.referencedVariables().count(name))
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// TODO If _value is null, we could use zero.
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m_value[name] = _value;
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}
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auto const& referencedVariables = movableChecker.referencedVariables();
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for (auto const& name: _variables)
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{
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m_references[name] = referencedVariables;
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for (auto const& ref: referencedVariables)
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m_referencedBy[ref].insert(name);
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}
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}
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void DataFlowAnalyzer::clearValues(set<string> const& _variables)
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{
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// All variables that reference variables to be cleared also have to be
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// cleared, but not recursively, since only the value of the original
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// variables changes. Example:
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// let a := 1
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// let b := a
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// let c := b
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// let a := 2
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// add(b, c)
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// In the last line, we can replace c by b, but not b by a.
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//
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// This cannot be easily tested since the substitutions will be done
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// one by one on the fly, and the last line will just be add(1, 1)
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set<string> variables = _variables;
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// Clear variables that reference variables to be cleared.
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for (auto const& name: variables)
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for (auto const& ref: m_referencedBy[name])
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variables.insert(ref);
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// Clear the value and update the reference relation.
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for (auto const& name: variables)
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m_value.erase(name);
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for (auto const& name: variables)
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{
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for (auto const& ref: m_references[name])
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m_referencedBy[ref].erase(name);
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m_references[name].clear();
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}
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}
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bool DataFlowAnalyzer::inScope(string const& _variableName) const
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{
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for (auto const& scope: m_variableScopes | boost::adaptors::reversed)
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{
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if (scope.first.count(_variableName))
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return true;
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if (scope.second)
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return false;
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}
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return false;
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}
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78
libjulia/optimiser/DataFlowAnalyzer.h
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78
libjulia/optimiser/DataFlowAnalyzer.h
Normal file
@ -0,0 +1,78 @@
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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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* Base class to perform data flow analysis during AST walks.
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* Tracks assignments and is used as base class for both Rematerialiser and
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* Common Subexpression Eliminator.
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*/
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#pragma once
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#include <libjulia/optimiser/ASTWalker.h>
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#include <string>
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#include <map>
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#include <set>
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namespace dev
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{
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namespace julia
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{
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/**
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* Base class to perform data flow analysis during AST walks.
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* Tracks assignments and is used as base class for both Rematerialiser and
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* Common Subexpression Eliminator.
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*
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* Prerequisite: Disambiguator
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*/
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class DataFlowAnalyzer: public ASTModifier
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{
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public:
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using ASTModifier::operator();
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virtual void operator()(Assignment& _assignment) override;
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virtual void operator()(VariableDeclaration& _varDecl) override;
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virtual void operator()(If& _if) override;
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virtual void operator()(Switch& _switch) override;
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virtual void operator()(FunctionDefinition&) override;
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virtual void operator()(ForLoop&) override;
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virtual void operator()(Block& _block) override;
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protected:
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/// Registers the assignment.
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void handleAssignment(std::set<std::string> const& _names, Expression* _value);
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/// Clears information about the valuse assigned to the given variables,
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/// for example at points where control flow is merged.
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void clearValues(std::set<std::string> const& _names);
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/// Returns true iff the variable is in scope.
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bool inScope(std::string const& _variableName) const;
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/// Current values of variables, always movable.
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std::map<std::string, Expression const*> m_value;
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/// m_references[a].contains(b) <=> the current expression assigned to a references b
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std::map<std::string, std::set<std::string>> m_references;
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/// m_referencedBy[b].contains(a) <=> the current expression assigned to a references b
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std::map<std::string, std::set<std::string>> m_referencedBy;
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/// List of scopes, where each scope is a set of variables and a bool that tells
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/// whether it is a function body (true) or not.
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std::vector<std::pair<std::set<std::string>, bool>> m_variableScopes;
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};
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}
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}
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@ -20,176 +20,35 @@
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#include <libjulia/optimiser/Rematerialiser.h>
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#include <libjulia/optimiser/Metrics.h>
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#include <libjulia/optimiser/ASTCopier.h>
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#include <libjulia/optimiser/NameCollector.h>
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#include <libsolidity/inlineasm/AsmData.h>
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#include <libjulia/optimiser/Semantics.h>
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#include <libdevcore/CommonData.h>
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#include <boost/range/adaptor/reversed.hpp>
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using namespace std;
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using namespace dev;
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using namespace dev::julia;
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void Rematerialiser::operator()(Assignment& _assignment)
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{
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set<string> names;
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for (auto const& var: _assignment.variableNames)
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names.insert(var.name);
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handleAssignment(names, _assignment.value.get());
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}
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void Rematerialiser::operator()(VariableDeclaration& _varDecl)
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{
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set<string> names;
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for (auto const& var: _varDecl.variables)
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names.insert(var.name);
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m_variableScopes.back().first += names;
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handleAssignment(names, _varDecl.value.get());
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}
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void Rematerialiser::operator()(If& _if)
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{
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ASTModifier::operator()(_if);
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Assignments ass;
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ass(_if.body);
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handleAssignment(ass.names(), nullptr);
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}
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void Rematerialiser::operator()(Switch& _switch)
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{
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boost::apply_visitor(*this, *_switch.expression);
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set<string> assignedVariables;
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for (auto& _case: _switch.cases)
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{
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(*this)(_case.body);
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Assignments ass;
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ass(_case.body);
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assignedVariables += ass.names();
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// This is a little too destructive, we could retain the old replacements.
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handleAssignment(ass.names(), nullptr);
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}
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handleAssignment(assignedVariables, nullptr);
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}
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void Rematerialiser::operator()(FunctionDefinition& _fun)
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{
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m_variableScopes.push_back(make_pair(set<string>(), true));
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for (auto const& parameter: _fun.parameters)
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m_variableScopes.back().first.insert(parameter.name);
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for (auto const& var: _fun.returnVariables)
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m_variableScopes.back().first.insert(var.name);
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ASTModifier::operator()(_fun);
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m_variableScopes.pop_back();
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}
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void Rematerialiser::operator()(ForLoop& _for)
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{
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// Special scope handling of the pre block.
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m_variableScopes.push_back(make_pair(set<string>(), false));
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for (auto& statement: _for.pre.statements)
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visit(statement);
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Assignments ass;
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ass(_for.body);
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ass(_for.post);
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handleAssignment(ass.names(), nullptr);
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visit(*_for.condition);
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(*this)(_for.body);
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(*this)(_for.post);
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handleAssignment(ass.names(), nullptr);
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m_variableScopes.pop_back();
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}
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void Rematerialiser::operator()(Block& _block)
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{
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size_t numScopes = m_variableScopes.size();
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m_variableScopes.push_back(make_pair(set<string>(), false));
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ASTModifier::operator()(_block);
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m_variableScopes.pop_back();
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solAssert(numScopes == m_variableScopes.size(), "");
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}
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void Rematerialiser::handleAssignment(set<string> const& _variables, Expression* _value)
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{
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MovableChecker movableChecker;
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if (_value)
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{
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visit(*_value);
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movableChecker.visit(*_value);
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}
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if (_variables.size() == 1)
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{
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string const& name = *_variables.begin();
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if (movableChecker.movable() && _value)
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// TODO Plus heuristic about size of value
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// TODO If _value is null, we could use zero.
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m_substitutions[name] = _value;
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else
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m_substitutions.erase(name);
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}
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else
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for (auto const& name: _variables)
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m_substitutions.erase(name);
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// Disallow substitutions that use a variable that will be reassigned by this assignment.
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for (auto const& name: _variables)
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for (auto const& ref: m_referencedBy[name])
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m_substitutions.erase(ref);
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// Update the fact which variables are referenced by the newly assigned variables
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for (auto const& name: _variables)
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{
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for (auto const& ref: m_references[name])
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m_referencedBy[ref].erase(name);
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m_references[name].clear();
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}
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auto const& referencedVariables = movableChecker.referencedVariables();
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for (auto const& name: _variables)
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{
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m_references[name] = referencedVariables;
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for (auto const& ref: referencedVariables)
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m_referencedBy[ref].insert(name);
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}
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}
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bool Rematerialiser::inScope(string const& _variableName) const
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{
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for (auto const& scope: m_variableScopes | boost::adaptors::reversed)
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{
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if (scope.first.count(_variableName))
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return true;
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if (scope.second)
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return false;
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}
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return false;
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}
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void Rematerialiser::visit(Expression& _e)
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{
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if (_e.type() == typeid(Identifier))
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{
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Identifier& identifier = boost::get<Identifier>(_e);
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if (m_substitutions.count(identifier.name))
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if (m_value.count(identifier.name))
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{
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string name = identifier.name;
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bool doSubstitute = true;
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bool expressionValid = true;
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for (auto const& ref: m_references[name])
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if (!inScope(ref))
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{
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doSubstitute = false;
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expressionValid = false;
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break;
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}
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if (doSubstitute)
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_e = (ASTCopier{}).translate(*m_substitutions.at(name));
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solAssert(m_value.at(name), "");
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auto const& value = *m_value.at(name);
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if (expressionValid && CodeSize::codeSize(value) <= 7)
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_e = (ASTCopier{}).translate(value);
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}
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}
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ASTModifier::visit(_e);
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DataFlowAnalyzer::visit(_e);
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}
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@ -20,7 +20,7 @@
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#pragma once
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#include <libjulia/optimiser/ASTWalker.h>
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#include <libjulia/optimiser/DataFlowAnalyzer.h>
|
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#include <string>
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#include <map>
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@ -36,37 +36,12 @@ namespace julia
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*
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* Prerequisite: Disambiguator
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*/
|
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class Rematerialiser: public ASTModifier
|
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class Rematerialiser: public DataFlowAnalyzer
|
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{
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public:
|
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using ASTModifier::operator();
|
||||
virtual void operator()(Assignment& _assignment) override;
|
||||
virtual void operator()(VariableDeclaration& _varDecl) override;
|
||||
virtual void operator()(If& _if) override;
|
||||
virtual void operator()(Switch& _switch) override;
|
||||
virtual void operator()(FunctionDefinition&) override;
|
||||
virtual void operator()(ForLoop&) override;
|
||||
virtual void operator()(Block& _block) override;
|
||||
|
||||
protected:
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using ASTModifier::visit;
|
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virtual void visit(Expression& _e) override;
|
||||
|
||||
private:
|
||||
void handleAssignment(std::set<std::string> const& _names, Expression* _value);
|
||||
|
||||
/// Returns true iff the variable is in scope.
|
||||
bool inScope(std::string const& _variableName) const;
|
||||
|
||||
/// Substitutions to be performed, if possible.
|
||||
std::map<std::string, Expression const*> m_substitutions;
|
||||
/// m_references[a].contains(b) <=> the current expression assigned to a references b
|
||||
std::map<std::string, std::set<std::string>> m_references;
|
||||
/// m_referencedBy[b].contains(a) <=> the current expression assigned to a references b
|
||||
std::map<std::string, std::set<std::string>> m_referencedBy;
|
||||
/// List of scopes, where each scope is a set of variables and a bool that tells
|
||||
/// whether it is a function body (true) or not.
|
||||
std::vector<std::pair<std::set<std::string>, bool>> m_variableScopes;
|
||||
};
|
||||
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user