This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: autovectorization in gcc
- From: Andrew Haley <aph at redhat dot com>
- To: Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>, "Kay F. Jahnke" <kfjahnke at gmail dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Wed, 9 Jan 2019 09:50:07 +0000
- Subject: Re: autovectorization in gcc
- References: <41ea83cd-0ce8-4f25-35e5-888513d69c7b@gmail.com> <5C35C2C2.1050106@foss.arm.com>
On 1/9/19 9:45 AM, Kyrill Tkachov wrote:
> Hi Kay,
>
> On 09/01/19 08:29, Kay F. Jahnke wrote:
>> Hi there!
>>
>> I am developing software which tries to deliberately exploit the
>> compiler's autovectorization facilities by feeding data in
>> autovectorization-friendly loops. I'm currently using both g++ and
>> clang++ to see how well this approach works. Using simple arithmetic, I
>> often get good results. To widen the scope of my work, I was looking for
>> documentation on which constructs would be recognized by the
>> autovectorization stage, and found
>>
>> https://www.gnu.org/software/gcc/projects/tree-ssa/vectorization.html
>>
>
> Yeah, that page hasn't been updated in ages AFAIK.
>
>> By the looks of it, this document has not seen any changes for several
>> years. Has development on the autovectorization stage stopped, or is
>> there simply no documentation?
>>
>
> There's plenty of work being done on auto-vectorisation in GCC.
> Auto-vectorisation is a performance optimisation and as such is not really
> a user-visible feature that absolutely requires user documentation.
I don't agree. Sometimes vectorization is critical. It would be nice
to have a warning which would fire if vectorization failed. That would
surely help the OP.
--
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671