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From "Egor Pasko (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-957) Devirtualize interface calls in DRLVM optimizing JIT-compiler (Jitrino.OPT)
Date Fri, 27 Oct 2006 05:42:17 GMT
    [ http://issues.apache.org/jira/browse/HARMONY-957?page=comments#action_12445086 ] 
Egor Pasko commented on HARMONY-957:

Geir, "patch available" status is great! But, unfortunately, not for this issue. The patch
(attached) is not mature enough, it does not solve the problem as we want it to. So, I would
consider such situations as "patch NOT available".

> Devirtualize interface calls in DRLVM optimizing JIT-compiler (Jitrino.OPT)
> ---------------------------------------------------------------------------
>                 Key: HARMONY-957
>                 URL: http://issues.apache.org/jira/browse/HARMONY-957
>             Project: Harmony
>          Issue Type: New Feature
>          Components: DRLVM
>         Environment: all
>            Reporter: Egor Pasko
>            Priority: Minor
>         Attachments: IntfcCaller.java, patch.zip
> Currently DRLVM does *not* devirtualize interface calls. 
> here are some ideas how to implement this feature (from easiest to complicated)
> 0) if there is only one loaded class to implement the interface, choose it
> 1) if there are more, choose the one with it's method invoked earlier (compiled  by some
JIT, possibly, some other JIT), 
> 2) if we have many candidate methods that are compiled, choose the most frequent  one
(need a method-entry profile)
> 3) initial compilation can devirtualize all possible dispatches and count their edge
frequencies so we can rely on basic profiler when choosing the best path (on recompilation)
> 4) implement a real value profiler - this is not an easy task, but may be reused in other
> 5) Add special annotations to classlib code about the most probable dispatch. E.g. if
the variable type does not depend on user's environment and developer can prove that 90% of
time the variable is of specific class - JIT can read this annotation from method during the
compilation and to devirtualize it.

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