[Mesa-dev] [PATCH V4] mesa: add SSE optimisation for glDrawElements

[Timothy Arceri]

On Wed, 2014-10-29 at 16:58 +1100, Timothy Arceri wrote:
> On Tue, 2014-10-28 at 22:14 +0000, Bruno Jimenez wrote:
> > Hi,
> > 
> > I haven't had time to play yet with OpenMP, but I have seen the assembly
> > it produces in my computer. If I enable SSE2 it can use it, and if I
> > enable SSE4.1 it uses the parallel max. But it uses unaligned loads, and
> > since we are trying to avoid them I don't know if we want to use just
> > OpenMP.
> > 
> > Processing the first unaligned elements by hand and using the
> > __builtin_assume_aligned as the article you link allows OpenMP to use
> > aligned loads.
> > 
> > Also, it must be noted that I am using GCC, I don't know what Clang may
> > produce (for the plain algorithms, as it doesn't support OpenMP if I
> > recall correctly).
> > 
> > When I have time I'll try to collect all the variants and make some kind
> > of benchmark between them to see if it is worthy to use any of them.
> > 
> > Also, do we know if 'count' has an upper bound? or if we can force the
> > array to be aligned so we don't have to worry about the first items?
> 
> I'm not sure about count but the indices array comes from the
> glDrawRangeElements() call so I don't think we can do anything about the
> alignment.

Sorry I meant glDrawElements()

>  
> 
> > 
> > BTW, Thanks for the article!
> > - Bruno
> > 
> > > 
> > > 
> > > > 
> > > > - Bruno
> > > > 
> > > > > 
> > > > > > - Bruno
> > > > > > 
> > > > > >> +      unsigned max_arr[4] __attribute__ ((aligned (16)));
> > > > > >> +      unsigned min_arr[4] __attribute__ ((aligned (16)));
> > > > > >> +      unsigned vec_count;
> > > > > >> +      __m128i max_ui4 = _mm_setzero_si128();
> > > > > >> +      __m128i min_ui4 = _mm_set1_epi32(~0U);
> > > > > >> +      __m128i ui_indices4;
> > > > > >> +      __m128i *ui_indices_ptr;
> > > > > >> +
> > > > [snip]
> > > 
> > > 
> > 
> > 
> 
> 
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