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From "Maksim Ananjev (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-5090) [drlvm][jit][opt]operator strength reduction
Date Sat, 17 Nov 2007 08:56:43 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-5090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12543266
] 

Maksim Ananjev commented on HARMONY-5090:
-----------------------------------------

Egor, 

I have some information on performance impact. 
It boosts Dacapo lusearch, pmd, luindex by 2% - 6%  and degrades xalan performance by 2% -
3%. I am investigating now the last point. That's why this version is probably not a final
one.

The basic ideas I used in this patch are described in "Operator Strength Reduction" paper
by Keith D. Cooper, L.Taylor Simoson, Christopher Vick.
However I had to reconsider some parts of the algorithm to make it run faster and be stable
on large amounts of code. I can describe it in details as soon as I am done with investigation
and fixing this degradation issue.

> [drlvm][jit][opt]operator strength reduction
> --------------------------------------------
>
>                 Key: HARMONY-5090
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5090
>             Project: Harmony
>          Issue Type: New Feature
>          Components: DRLVM
>         Environment: Hope it works everywhere
>            Reporter: Maksim Ananjev
>            Priority: Minor
>         Attachments: HARMONY-5090.patch
>
>
> Operator Strength Reduction is an optimization that reformulates costly operations in
terms of less expensive ones.
> The simplest possible example is the following:
> before:
> int sum = 0;
> for(int i=0; i<10;i++){
> int temp = i * 10;
> sum+=temp
> }
> after:
> int sum = 0;
> for(int j=0; j<100; j+=10){
> sum+=j
> } 

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