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

[Bruno Jimenez]

On Sun, 2014-11-09 at 14:24 +1100, Timothy Arceri wrote:
> On Sat, 2014-11-08 at 18:25 +0000, Emil Velikov wrote:
> > On 08/11/14 08:35, Siavash Eliasi wrote:
> > > This will remove the need for unnecessary runtime checks for CPU features if
> > > already supported by target CPU, resulting in smaller and less branchy code.
> > > 
> > 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"
> 
> Hehe, you are technically correct, the best kind of correct.
> 
> >  
> > 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 :'(
> 
> I considered trying to work on a solution for this where anyone could
> volunteer their machine to run such tests and send the results back to a
> central server. But in the end its a pretty big project to get something
> like this working correctly, and making it easy to setup thus
> participate in.
> 
> I guess you could leverage something like the oibaf ppa to start with
> rather than pulling down each commit and building. Anyway a much bigger
> project than what I have time for at the moment.

Maybe it isn't needed for every commit. Depending on the architecture
you are testing you would focus on some commits. For example, I have a
radeon with the r600 driver, so I don't need to check all the intel and
nvidia related commits.

Even if it's not feasible for every commit, we may try to do it for
individual series. Or even, we may send some commits with some kind of
'request for test for performance'.

But we would need to have some kind of standarized benchmark/tests for
this, à la piglit.

Just my opinion :)
- Bruno
> 
> > 
> > But on a more mature note, currently only cpu_has_xmm
> > (_tnl_generate_sse_emit) and cpu_has_sse4_1(vbo_get_minmax_index) are
> > actually useful, with the former of questionable amount :P
> > 
> > Can you confirm that it does not cause issues with "interesting" setups
> > such as https://bugs.freedesktop.org/show_bug.cgi?id=71547
> > 
> 
> I think this patch should be find in this case as the solution there was
> to wrap the code with #ifdef __SSE4_1__ which is what makes this patch
> work. 
> 
> > 
> > Thanks
> > Emil
> > 
> > > V2:
> > > - Removed the SSSE3 related part for the not yet merged patch.
> > > - Avoiding redefinition of macros.
> > > ---
> > >  src/mesa/x86/common_x86_features.h | 26 ++++++++++++++++++++++++++
> > >  1 file changed, 26 insertions(+)
> > > 
> > > diff --git a/src/mesa/x86/common_x86_features.h b/src/mesa/x86/common_x86_features.h
> > > index 66f2cf6..65634aa 100644
> > > --- a/src/mesa/x86/common_x86_features.h
> > > +++ b/src/mesa/x86/common_x86_features.h
> > > @@ -59,13 +59,39 @@
> > >  #define X86_CPUEXT_3DNOW_EXT	(1<<30)
> > >  #define X86_CPUEXT_3DNOW	(1<<31)
> > >  
> > > +#ifdef __MMX__
> > > +#define cpu_has_mmx		1
> > > +#else
> > >  #define cpu_has_mmx		(_mesa_x86_cpu_features & X86_FEATURE_MMX)
> > > +#endif
> > > +
> > >  #define cpu_has_mmxext		(_mesa_x86_cpu_features & X86_FEATURE_MMXEXT)
> > > +
> > > +#ifdef __SSE__
> > > +#define cpu_has_xmm		1
> > > +#else
> > >  #define cpu_has_xmm		(_mesa_x86_cpu_features & X86_FEATURE_XMM)
> > > +#endif
> > > +
> > > +#ifdef __SSE2__
> > > +#define cpu_has_xmm2		1
> > > +#else
> > >  #define cpu_has_xmm2		(_mesa_x86_cpu_features & X86_FEATURE_XMM2)
> > > +#endif
> > > +
> > > +#ifdef __3dNOW__
> > > +#define cpu_has_3dnow		1
> > > +#else
> > >  #define cpu_has_3dnow		(_mesa_x86_cpu_features & X86_FEATURE_3DNOW)
> > > +#endif
> > > +
> > >  #define cpu_has_3dnowext	(_mesa_x86_cpu_features & X86_FEATURE_3DNOWEXT)
> > > +
> > > +#ifdef __SSE4_1__
> > > +#define cpu_has_sse4_1		1
> > > +#else
> > >  #define cpu_has_sse4_1		(_mesa_x86_cpu_features & X86_FEATURE_SSE4_1)
> > > +#endif
> > >  
> > >  #endif
> > >  
> > > 
> > 
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev
> 
> 
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