Subject: Re: BUG #15121: Multiple UBSAN errors
To: =?UTF-8?Q?Martin_Li=c5=a1ka?= <marxin.liska@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org,
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 <CAObPJ3MAY9u1had3QSvYO0TG-iVECqDzF04PvMZSHrmxNknZ8Q@mail.gmail.com>
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Message-ID: <46a345c1-1f8d-fd0d-c334-d8ca577719a9@2ndquadrant.com>
Date: Mon, 19 Mar 2018 15:26:12 +0100
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On 03/19/2018 09:59 AM, Martin Liška wrote:
> On 19 March 2018 at 01:34, Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:
>
> ...
>>
>> Again, the line numbers don't really match the code I have, but I guess
>> it's the same issue as for pg_comp_crc32c_sse42. This is apparently
>> related to array serialization, and I guess we have a compact structure
>> (intentionally, to make it smaller), and we accept the unaligned access.
> 
> Note that building postgresql with -03, I see some array tests failing.
> 

I'm unable to reproduce that. I do get a bunch of compile-time warnings
about possibly uninitialized variables (which seem bogus after a quick
inspection), but no failures.

Which gcc version are you using? Mine is 6.4.1. Do the failures happen
every time or rarely?

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services