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From "Aleksey Shipilev (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-5584) [drlvm][jit][opt][performance] Inliner heuristics improvements: hotness and instance initializer bonuses
Date Tue, 18 Mar 2008 14:27:24 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-5584?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12579864#action_12579864
] 

Aleksey Shipilev commented on HARMONY-5584:
-------------------------------------------

Well, according to my measurements, this change is necessary to inline nextDouble() and also
it's not degrading the performance of other workloads. 

Can we fix the failure in regression tests instead? Is this issue directly caused by increasing
of growth factor? It's strange how inline might break them.

> [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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