I've been wanting to use -mfpmath=sse as it be beneficial (I've
benchmarked it myself) however, it would limit us to the PIII ('99) and
the Athlon 4 (2001). While for the Athlon that was 6 years ago, I'm not
convinced we don't have a significant userbase still running us on
machines pre-sse. (coincidentally this was one of the unanswered
questions that inspired Case Metrics... so we should have a better idea
after this release).
I can see your point with the -march option, however my only concern is
with 64-bit builds. I don't currently know of a way to test for 64/32-bit
in Scons and specifying -march=pentium would mean we always compile 32-bit
(Being a 64-bit user I don't much like the idea of that :)).
So I guess I'd summarize my opinion as:
-mfpmath=sse: Not yet
-march=pentium: Not until we find a way to make sure this doesn't affect
64-bit builds
-John
> Albert Santoni wrote:
>> Ok, couple of problems:
>>
>> 1) We already have -O3 in two other places on unix (always turned on).
>> We really do want these turned on by default on unix, so I've removed
>> the -O3 from the other spots and made your optimizations block enabled
>> by default on unix.
>
> It is worthwhile to specify whether the CPU is a pentium or not:
> i.e.: -march=pentium
> since this enables more efficient float <=> int conversion. The
> performance penalty of the stock GCC conversion is rather large.
>
> if you can figure out during configuration whether the architecture is
> i686 and supports mmx/sse, the following will gain you even more float
> performance:
> -mmmx -msse -mfpmath=sse
>
> Some more general GCC optimization flags:
> -fomit-frame-pointer -ffast-math -funroll-loops
>
> Especially the inclusion of floating point math optimization will give
> you a lot of improvement. And who uses mixxx on a 486 anyway?
>
> Greets,
>
> Pieter
>
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