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Posted to issues@impala.apache.org by "Bikramjeet Vig (JIRA)" <ji...@apache.org> on 2018/03/29 20:10:00 UTC

[jira] [Resolved] (IMPALA-5980) Upgrade to LLVM 5.0.1

     [ https://issues.apache.org/jira/browse/IMPALA-5980?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bikramjeet Vig resolved IMPALA-5980.
------------------------------------
       Resolution: Fixed
    Fix Version/s: Impala 2.13.0

> Upgrade to LLVM 5.0.1
> ---------------------
>
>                 Key: IMPALA-5980
>                 URL: https://issues.apache.org/jira/browse/IMPALA-5980
>             Project: IMPALA
>          Issue Type: Improvement
>          Components: Backend
>            Reporter: Bikramjeet Vig
>            Assignee: Bikramjeet Vig
>            Priority: Major
>              Labels: codegen
>             Fix For: Impala 2.13.0
>
>         Attachments: image.png
>
>
> As a part of IMPALA-5907 it was identified that the GVN optimization pass is slow for large cases, specifically when huge expression trees are passed to it. 
>  This slow GVN pass problem is a known issue ([https://groups.google.com/forum/#!msg/llvm-dev/ozsAceDmOuA/2O_QC6EiDgAJ]) that has motivated the llvm devs to develop a new GVN pass which is claimed to be faster and is available in LLVM 5.0.1
>  Therefore after upgrading to LLVM 5.0.1 we should try moving to the NewGVN pass and figure out if it is helpful by doing a perf analysis.



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