[jira] Assigned: (HARMONY-5837) [drlvm][jit][opt] Code layout and alignment improvements

["Mikhail Fursov (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HARMONY-5837?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mikhail Fursov reassigned HARMONY-5837:
---------------------------------------

    Assignee: Mikhail Fursov

> [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
>          Components: DRLVM
>         Environment: IA32
>            Reporter: Dmitry Pronichkin
>            Assignee: Mikhail Fursov
>         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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