Re: pgsql: Improve performance of SendRowDescriptionMessage.

On 2017-10-12 19:35:36 -0700, Noah Misch wrote:
> On Thu, Oct 12, 2017 at 04:08:44PM -0700, Andres Freund wrote:
> > So we've two animals (hornet, sungazer) that are:
> > #define SIZEOF_SIZE_T 8
> > #define WORDS_BIGENDIAN 1
> > #define restrict __restrict
> >
> > one compiled with xlc that fails and one with gcc that succeeds. I'm
> > hesitant to reach for that, but I wonder if there's a compiler
> > bug. Alternatively there could be some undefined behaviour here that
> > only triggers on xlc 64bit, but I'm not quite seeing it.
> >
> > Noah, any chance you could force restrict to off on that animal?
>
> I can confirm it allows "make check" to pass. Specifically, I did this
> against commit 91d5f1a:
>
> --- src/include/pg_config.h~ 2017-10-12 18:11:33.000000000 -0700
> +++ src/include/pg_config.h 2017-10-12 18:22:34.000000000 -0700
> @@ -929 +929 @@
> - #define pg_restrict __restrict
> + #define pg_restrict
> @@ -934 +934 @@
> - #define restrict __restrict
> + #define restrict
>
> I have no reason to believe this is specific to hornet's installation, so I
> recommend against altering hornet's configuration. It's too likely that the
> next xlc user will need to do the same thing.

Yea, I wasn't trying to propose that - I just thought it'd be easier to
narrow down with access to the machine than 6h cycle buildfarm
debugging.

> > Otherwise I can push a platform fix that disables it.
>
> This sounds reasonable.

I'm not getting a great vibe about the aix/xlc quality in this thread :(

Greetings,

Andres Freund