[Mesa-dev] [PATCH V2] mesa: Permanently enable features supported by target CPU at compile time.

[Siavash Eliasi]

On 11/08/2014 09:55 PM, Emil Velikov wrote:
> A comment I could not withheld based on your earlier post - "We require
> micro-benchmark for this code. It will take me hours to find why mesa is
> so slow now :P"

Which brings the question why didn't you post to that thread/topic in 
first place instead :P

> Ideally mesa should have an infrastructure/farm that handles regressions
> - be that performance or otherwise. Pretty sure some companies have such
> features but those seem to be hidden behind locked doors :'(

Yes, that's unfortunate. But atleast we have Phoronix :)

> Can you confirm that it does not cause issues with "interesting" setups
> such as https://bugs.freedesktop.org/show_bug.cgi?id=71547

Challenge accepted! What my patch is doing is to check for provided 
compile flags (-msse, ...) on compile time (__SSE__, ...) and set 
"cpu_has_sse" macro to "1" which allows any sane compiler to turn this 
pieces of code:

#ifdef USE_SSE
if (cpu_has_sse)
{
/* SSE code path */
}
else
#endif
{
/* C fallback */
}

into this:

/* SSE code path */

by using compile time information by target CPU.

Best regards,
Siavash Eliasi.