Hi,
On Thu, Nov 14, 2024 at 09:13:19AM -0300, Ranier Vilela wrote:
> Em qui., 14 de nov. de 2024 às 08:58, Bertrand Drouvot <
> Maybe I'm doing something wrong.
> But I'm testing in 32-bit, with the size set to 63, with v12 and I'm seeing
> the SIMD loop execute.
Yeah, that's expected and safe as each iteration reads 32 bytes on 32-bit.
> if (len < sizeof(size_t) * 8) // 8-63 bytes
> failed.
>
> I expected that with size 63, it would be solved by case 2, or am I wrong?
Case 2 should be read as "in the 4-31" bytes range on 32-bit system as all
comparisons are done in size_t.
What would be unsafe on 32-bit would be to read up to 32 bytes while len < 32
and that can not happen.
As mentioned up-thread the comments are wrong on 32-bit, indeed they must be read
as:
Case 1: len < 4 bytes
Case 2: len in the 4-31 bytes range
Case 3: len >= 32 bytes
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
