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Date: Fri, 23 May 2008 05:09:55 -0700 (PDT)
From: "Dmitry Pronichkin (JIRA)" <jira@apache.org>
To: commits@harmony.apache.org
Subject: [jira] Updated: (HARMONY-5837) [drlvm][jit][opt] Code layout and
 alignment improvements
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     [ https://issues.apache.org/jira/browse/HARMONY-5837?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dmitry Pronichkin updated HARMONY-5837:
---------------------------------------

    Attachment:     (was: alignment.patch)

> [drlvm][jit][opt] Code layout and alignment improvements
> --------------------------------------------------------
>
>                 Key: HARMONY-5837
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5837
>             Project: Harmony
>          Issue Type: Improvement
>         Environment: IA32
>            Reporter: Dmitry Pronichkin
>         Attachments: alignment.patch, Ia32LayoutOpt.cpp
>
>
> Code layout (control flow graph linearization) "bottom-up" algorithm was optimized. Less probable branches were carried out of main code layout order by algorithm and it was not always good (tested on microbenches). New codegen pass "layout_opt" inserts such branches back depending on branch probability and block size (these parameters are set through configuration).
> Code alignment improvements include two heuristics. First is to align basic blocks that are much hotter than their layout predecessors (threshold is set in configuration). Second is to align basic blocks unreachable from their layout predecessors. These heuristics are implemented in emitter and alignment for loop headers was eliminated because it's a special case of first alignment heuristic.

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