[jira] [Updated] (SYSTEMML-1719) Common subexpression elimination for codegen plans

["Glenn Weidner (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SYSTEMML-1719?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Glenn Weidner updated SYSTEMML-1719:
------------------------------------
    Fix Version/s:     (was: SystemML 1.0)
                   SystemML 0.15

> Common subexpression elimination for codegen plans
> --------------------------------------------------
>
>                 Key: SYSTEMML-1719
>                 URL: https://issues.apache.org/jira/browse/SYSTEMML-1719
>             Project: SystemML
>          Issue Type: Sub-task
>          Components: Compiler, Runtime
>            Reporter: Matthias Boehm
>            Assignee: Matthias Boehm
>             Fix For: SystemML 0.15
>
>
> There are a number of scenarios, where the code generator currently produces suboptimal plans due to missing common subexpression elimination. This happens commonly for multi-aggregates:
> {code}
> public final class TMP32 extends SpoofMultiAggregate { 
>   public TMP32() {
>     super(AggOp.SUM,AggOp.SUM);
>   }
>   protected void genexec(double a, SideInput[] b, double[] scalars, double[] c, int m, int n, int rowIndex, int colIndex) { 
>     double TMP26 = getValue(b[1], rowIndex);
>     double TMP27 = getValue(b[0], rowIndex);
>     double TMP28 = TMP26 + scalars[0] * TMP27;
>     double TMP29 = TMP28 * TMP28;
>     double TMP30 = getValue(b[0], rowIndex);
>     double TMP31 = TMP30 * a;
>     c[0] += TMP29;
>     c[1] += TMP31;
>   }
> }
> {code}
> Beside these scenarios, common subexpression elimination would also help to achieve higher plan cache hit rates.



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