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From "Chengxiang Li (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-10180) Loop optimization for SIMD in ColumnArithmeticColumn.txt
Date Tue, 07 Apr 2015 07:21:12 GMT

     [ https://issues.apache.org/jira/browse/HIVE-10180?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Chengxiang Li updated HIVE-10180:
---------------------------------
    Attachment: HIVE-10180.2.patch

Set new variables to final.

> Loop optimization for SIMD in ColumnArithmeticColumn.txt
> --------------------------------------------------------
>
>                 Key: HIVE-10180
>                 URL: https://issues.apache.org/jira/browse/HIVE-10180
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: Chengxiang Li
>            Assignee: Chengxiang Li
>            Priority: Minor
>         Attachments: HIVE-10180.1.patch, HIVE-10180.2.patch
>
>
> JVM is quite strict on the code schema which may executed with SIMD instructions, take
a loop in DoubleColAddDoubleColumn.java for example, 
> {code:java}
> for (int i = 0; i != n; i++) {
>   outputVector[i] = vector1[0] + vector2[i];
> }
> {code}
> The "vector1[0]" reference would prevent JVM to execute this part of code with vectorized
instructions, we need to assign the "vector1[0]" to a variable outside of loop, and use that
variable in loop.



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