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Re: [patch] Excessive alignment in ix86_data_alignment
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Uros Bizjak <ubizjak at gmail dot com>
- Cc: Kirill Yukhin <kirill dot yukhin at gmail dot com>, Petr Murzin <petrmurzin1 at gmail dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 9 Oct 2014 08:25:30 -0700
- Subject: Re: [patch] Excessive alignment in ix86_data_alignment
- Authentication-results: sourceware.org; auth=none
- References: <CANDVG5j-codZpjAoRVsEUUxdNpGPKHzP4VFX50kc9o8ivsa6Pg at mail dot gmail dot com> <20141009082454 dot GA61071 at msticlxl57 dot ims dot intel dot com> <CAFULd4YaYHVZ-rSG7WmPiSR3q71vYp1kox=5pT=S9LqdpTCrFA at mail dot gmail dot com>
On Thu, Oct 9, 2014 at 1:37 AM, Uros Bizjak <email@example.com> wrote:
> On Thu, Oct 9, 2014 at 10:25 AM, Kirill Yukhin <firstname.lastname@example.org> wrote:
>> On 08 Oct 23:02, Petr Murzin wrote:
>>> I have measured performance impact on Haswell platform according to this
Kirill, please mention:
in your ChangeLog.
> What about older processors?
Kirill, please collect data on Nehelam/Westmere, Sandybrigde/Ivybride
> The optimization was introduced well before Haswell for then current
> processors, and it was based on the recommendation from Intel
> optimization guide. If this optimization doesn't apply for new
> processors, then tune option should be introduced and set accordingly.
I believe the original excessive alignment was introduced by cut/paste
to improve x86 FP performance, which might be partially copied from