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Date: Wed, 12 Mar 2008 05:22:46 -0700 (PDT)
From: "Mikhail Fursov (JIRA)" <jira@apache.org>
To: commits@harmony.apache.org
Subject: [jira] Assigned: (HARMONY-5584) [drlvm][jit][opt][performance]
 Inliner heuristics improvements: hotness and instance initializer bonuses
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     [ https://issues.apache.org/jira/browse/HARMONY-5584?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mikhail Fursov reassigned HARMONY-5584:
---------------------------------------

    Assignee: Mikhail Fursov

> [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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