This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: How to get GCC on par with ICC?
- From: Steve Ellcey <sellcey at cavium dot com>
- To: NightStrike <nightstrike at gmail dot com>, joel at rtems dot org
- Cc: Paul Menzel <pmenzel+gcc dot gnu dot org at molgen dot mpg dot de>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Thu, 21 Jun 2018 16:05:09 -0700
- Subject: Re: How to get GCC on par with ICC?
- References: <CAF1jjLuoNjPrpWQL4fiwCBs2-xJX2MR7GDdhWYPhWGvXdKG8kA@mail.gmail.com>
- Reply-to: sellcey at cavium dot com
- Spamdiagnosticmetadata: NSPM
- Spamdiagnosticoutput: 1:99
On Wed, 2018-06-20 at 17:11 -0400, NightStrike wrote:
>
> If I could perhaps jump in here for a moment... Just today I hit upon
> a series of small (in lines of code) loops that gcc can't vectorize,
> and intel vectorizes like a madman. They all involve a lot of heavy
> use of std::vector<std::vector<float>>. Comparisons were with gcc
> 8.1, intel 2018.u1, an AMD Opteron 6386 SE, with the program running
> as sched_FIFO, mlockall, affinity set to its own core, and all
> interrupts vectored off that core. So, as close to not-noisy as
> possible.
There are a quite a number of bugzilla reports with examples where GCC
does not vectorize a loop. I wonder if this example is related to PR
61247.
Steve Ellcey