Re: Improve CRC32C performance on SSE4.2

On Mon, Jun 23, 2025 at 10:05 PM Nathan Bossart
<nathandbossart@gmail.com> wrote:
>
> On Mon, Jun 23, 2025 at 10:51:21AM -0400, Tom Lane wrote:
> > This has broken the build completely on my RHEL8 x86_64 box,
> > with gcc 8.5.0:
> >
> > $ ./configure ...
> > $ make -s
> > pg_crc32c_sse42.c: In function 'pg_comp_crc32c_avx512':
> > pg_crc32c_sse42.c:126:25: warning: implicit declaration of function '_mm512_zextsi128_si512'; did you mean
'_mm512_castsi128_si512'?[-Wimplicit-function-declaration] 
> >    x0 = _mm512_xor_si512(_mm512_zextsi128_si512(_mm_cvtsi32_si128(crc0)), x0);
> >                          ^~~~~~~~~~~~~~~~~~~~~~
> >                          _mm512_castsi128_si512
>
> It looks like thse weren't added until GCC 10 [0].

Huh, that's surprising because the Intel manual put it in AVX-512F,
the basic core around which everything else is tacked on.

--
John Naylor
Amazon Web Services