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