[Ubuntu 15.10] gcc: POWER8 unaligned vector access performance

[bugproxy]

POWER8 hardware provides much better performance for unaligned vector memory references than previous processors. However, GCC hadn't previously caught up with the vectorization modeling for this. I now have patches upstream for this, implemented with the following revisions:

GCC trunk (version 6): 222349, 222372
GCC 5.1: 222386, 222395
GCC 4.9: 222412
GCC 4.8: 222423

I would like to see the backported patch applied to the gcc shipped with the Ubuntu 15.10 release. We should also discuss applying it to the next available service pack for the 14.04 LTS release.

[Ubuntu Foundations Team Bug Bot (crichton)]

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[Steve Langasek (vorlon)]

It looks like this bug will be fixed as a matter of course when gcc 5.1 is included in the distro and becomes the default in Ubuntu 15.10. Assigning to Matthias for confirmation.

[Steve Langasek (vorlon)]

gcc 5.2.1 is now the default in wily, so I believe this issue is resolved for 15.10.

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2015-08-27 13:14 EDT-------
Closed at IBM side since Ubuntu already have gcc version 5,2 (5.2.1-15ubuntu2).