Re: Popcount optimization using AVX512

On 2024-Apr-02, Nathan Bossart wrote:

> Another idea I had is to turn pg_popcount() into a macro that just uses the
> pg_number_of_ones array when called for few bytes:
>
> static inline uint64
> pg_popcount_inline(const char *buf, int bytes)
> {
> uint64 popcnt = 0;
>
> while (bytes--)
> popcnt += pg_number_of_ones[(unsigned char) *buf++];
>
> return popcnt;
> }
>
> #define pg_popcount(buf, bytes) \
> ((bytes < 64) ? \
> pg_popcount_inline(buf, bytes) : \
> pg_popcount_optimized(buf, bytes))
>
> But again, I'm not sure this is really worth it for the current use-cases.

Eh, that seems simple enough, and then you can forget about that case.

--
Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/
"No hay hombre que no aspire a la plenitud, es decir,
la suma de experiencias de que un hombre es capaz"