[Bug 1449118] Re: [Ubuntu 15.10] gcc: POWER8 unaligned vector access performance

[Steve Langasek]

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.

** Package changed: ubuntu => gcc-defaults (Ubuntu)

** Changed in: gcc-defaults (Ubuntu)
       Status: New => In Progress

** Changed in: gcc-defaults (Ubuntu)
     Assignee: (unassigned) => Matthias Klose (doko)

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https://bugs.launchpad.net/bugs/1449118

Title:
  [Ubuntu 15.10] gcc: POWER8 unaligned vector access performance

Status in gcc-defaults package in Ubuntu:
  In Progress

Bug description:
  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.

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