Big-Data-HPC-Platform/ecl/hqlcpp/hqlpopt.cpp

/*##############################################################################

    Copyright (C) 2011 HPCC Systems.

    All rights reserved. This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program 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 Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
############################################################################## */
#include "jliball.hpp"
#include "hql.hpp"

#include "platform.h"
#include "jlib.hpp"
#include "jexcept.hpp"
#include "jmisc.hpp"
#include "javahash.hpp"
#include "jmd5.hpp"
#include "jfile.hpp"
#include "eclhelper.hpp"

#include "hqlfunc.hpp"

#include "hqlattr.hpp"
#include "hqlcpp.ipp"
#include "hqlpopt.hpp"

//Optimize IF(a,b,c) op x to IF(a,b op x, c OP x)
//But be careful because it uncommons attributes increasing the size of the queries.
static IHqlExpression * peepholeOptimizeCompare(BuildCtx & ctx, IHqlExpression * expr)
{
    IHqlExpression * lhs = expr->queryChild(0);
    if (ctx.queryMatchExpr(lhs))
        return LINK(expr);

    IHqlExpression * rhs = expr->queryChild(1);
    if (!rhs->isConstant() || (lhs->getOperator() != no_if))
        return LINK(expr);

    IHqlExpression * ifCond = lhs->queryChild(0);
    IHqlExpression * ifTrue = lhs->queryChild(1);
    IHqlExpression * ifFalse = lhs->queryChild(2);
    assertex(ifFalse);

    node_operator op = expr->getOperator();
    OwnedHqlExpr newTrue = createValue(op, makeBoolType(), LINK(ifTrue), LINK(rhs));
    OwnedHqlExpr newFalse = createValue(op, makeBoolType(), LINK(ifFalse), LINK(rhs));
    OwnedHqlExpr newIf = createValue(no_if, makeBoolType(), LINK(ifCond), peepholeOptimize(ctx, newTrue), peepholeOptimize(ctx, newFalse));
    return expr->cloneAllAnnotations(newIf);
}


//Optimize search [not] in set(ds, value) to
//[not] exists(ds, value=search); - really need link counts on the expressions, and should be done in the real optimizer

IHqlExpression * peepholeOptimize(BuildCtx & ctx, IHqlExpression * expr)
{
    switch (expr->getOperator())
    {
    case no_eq:
    case no_ne:
    case no_le:
    case no_lt:
    case no_ge:
    case no_gt:
        return peepholeOptimizeCompare(ctx, expr);
    case no_and:
    case no_or:
    case no_not:
        {
            HqlExprArray args;
            bool same = true;
            ForEachChild(i, expr)
            {
                IHqlExpression * cur = expr->queryChild(i);
                IHqlExpression * optimized = peepholeOptimize(ctx, expr);
                args.append(*optimized);
                if (cur != optimized)
                    same = false;
            }
            if (!same)
                return expr->clone(args);
            break;
        }
    }
    return LINK(expr);
}