Re: define pg_structiszero(addr, s, r)

Hi,

On Tue, Nov 12, 2024 at 01:32:36PM -0300, Ranier Vilela wrote:
> It seems to me that it is enough to protect the SIMD loop when the size is
> smaller.
>
> if (len > sizeof(size_t) * 8)
> {
> for (; p < aligned_end - (sizeof(size_t) * 7); p += sizeof(size_t) *
> 8)
> {
> if ((((size_t *) p)[0] != 0) | (((size_t *) p)[1] != 0) |
> (((size_t *) p)[2] != 0) | (((size_t *) p)[3] != 0) |
> (((size_t *) p)[4] != 0) | (((size_t *) p)[5] != 0) |
> (((size_t *) p)[6] != 0) | (((size_t *) p)[7] != 0))
> return false;
> }
> }
>
> See v1_allzeros_small.c attached.

Thanks for looking at it!

It's not enough, as that would not fix the second reason mentioned in [1].

[1]: https://www.postgresql.org/message-id/ZzLxAJuGzyqA7cUo%40ip-10-97-1-34.eu-west-3.compute.internal

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com