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From "Egor Pasko (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-5584) [drlvm][jit][opt][performance] Inliner heuristics improvements: hotness and instance initializer bonuses
Date Thu, 20 Mar 2008 14:27:26 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-5584?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12580775#action_12580775
] 

Egor Pasko commented on HARMONY-5584:
-------------------------------------

Alexey,

estimation sounds great!

that's probably because most is compiled by JET, or is it including JET code? BTW, we also
should count bytecode mapping and inline mapping... this is what you probably meant by data
of VM structures. But they are affected by inliner.

> [drlvm][jit][opt][performance] Inliner heuristics improvements: hotness and instance
initializer bonuses
> --------------------------------------------------------------------------------------------------------
>
>                 Key: HARMONY-5584
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5584
>             Project: Harmony
>          Issue Type: Improvement
>         Environment: all
>            Reporter: Aleksey Shipilev
>            Assignee: Mikhail Fursov
>         Attachments: H5584-inliner-heuristics.patch
>
>
> During the profiling of Scimark2 [1] it was found that inliner misses the inline opportunities
for monte_carlo. 
> This is the code for hottest method:
> 	public static final double integrate(int Num_samples)
> 	{
> 		Random R = new Random(SEED);
> 		int under_curve = 0;
> 		for (int count=0; count<Num_samples; count++)
> 		{
> 			double x= R.nextDouble();
> 			double y= R.nextDouble();
> 			if ( x*x + y*y <= 1.0)
> 				 under_curve ++;
> 			
> 		}
> 		return ((double) under_curve / Num_samples) * 4.0;
> 	}
> Problems are:
>  1. nextDouble is not inlined
>  2. nextDouble is internally synchronized 
> Attached patch solves these two problems:
>  1. fixing hotness bonus calculation. This is the issue Random.nextDouble() hit on: this
method called in hot cycle and missing inline opportunity due to glitch in scaling function,
which should be more additive rather than multiplicative.
>  2. introducing instance initializer bonus. This helps to inline constructor with all
corresponding methods to help scalar replacement with scalarizing of R (and eliminating synchronization
too).

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