HoistAggregate.h

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/*
 * Souffle - A Datalog Compiler
 * Copyright (c) 2018, The Souffle Developers. All rights reserved
 * Licensed under the Universal Permissive License v 1.0 as shown at:
 * - https://opensource.org/licenses/UPL
 * - <souffle root>/licenses/SOUFFLE-UPL.txt
 */
 
/************************************************************************
 *
 * @file HoistAggregate.h
 *
 ***********************************************************************/
 
#pragma once
 
#include "ram/Program.h"
#include "ram/TranslationUnit.h"
#include "ram/analysis/Level.h"
#include "ram/transform/Transformer.h"
#include <string>
 
namespace souffle::ram::transform {
 
/**
 * @class HoistAggregatesTransformer
 * @brief Pushes one Aggregate as far up the loop nest as possible
 *
 * This transformer, if possible, pushes an aggregate up
 * the loop nest to increase performance by performing less Aggregate
 * operations
 *
 */
class HoistAggregateTransformer : public Transformer {
public:
    std::string getName() const override {
        return "HoistAggregateTransformer";
    }
 
    /**
     * @brief Apply hoistAggregate to the whole program
     * @param RAM program
     * @result A flag indicating whether the RAM program has been changed.
     *
     * Pushes an Aggregate up the loop nest if possible
     */
    bool hoistAggregate(Program& program);
 
protected:
    analysis::LevelAnalysis* rla{nullptr};
    bool transform(TranslationUnit& translationUnit) override {
        rla = translationUnit.getAnalysis<analysis::LevelAnalysis>();
        return hoistAggregate(translationUnit.getProgram());
    }
};
 
}  // namespace souffle::ram::transform