On Mon, Aug 26, 2024 at 06:44:55PM +0000, Amonson, Paul D wrote:
>> I'm curious about where exactly the regression is coming from. Is it possible
>> that your build for the SSE 4.2 tests was using it unconditionally, i.e.,
>> optimizing away the function pointer?
>
> I am calling the SSE 4.2 implementation directly; I am not even building
> the pg_sse42_*_choose.c file with the AVX512 choice. As best I can tell
> there is one extra function call and one extra int64 conditional test
> when bytes are <256 and a of course a JMP instruction to skip the AVX512
> implementation.
And this still shows the ~14% regression in your original post?
--
nathan