| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
| Cc: | David Rowley <dgrowleyml(at)gmail(dot)com>, Ants Aasma <ants(dot)aasma(at)cybertec(dot)at>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, "Amonson, Paul D" <paul(dot)d(dot)amonson(at)intel(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, "Shankaran, Akash" <akash(dot)shankaran(at)intel(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Popcount optimization using AVX512 |
| Date: | 2024-04-08 00:42:12 |
| Message-ID: | 2999492.1712536932@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Nathan Bossart <nathandbossart(at)gmail(dot)com> writes:
> Here is what I have staged for commit, which I intend to do shortly.
Today's Coverity run produced this warning, which seemingly was
triggered by one of these commits, but I can't make much sense
of it:
*** CID 1596255: Uninitialized variables (UNINIT)
/usr/lib/gcc/x86_64-linux-gnu/10/include/avxintrin.h: 1218 in _mm256_undefined_si256()
1214 extern __inline __m256i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
1215 _mm256_undefined_si256 (void)
1216 {
1217 __m256i __Y = __Y;
>>> CID 1596255: Uninitialized variables (UNINIT)
>>> Using uninitialized value "__Y".
1218 return __Y;
1219 }
I see the same code in my local copy of avxintrin.h,
and I quite agree that it looks like either an undefined
value or something that properly ought to be an error.
If we are calling this, why (and from where)?
Anyway, we can certainly just dismiss this warning if it
doesn't correspond to any real problem in our code.
But I thought I'd raise the question.
regards, tom lane
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