[fpc-devel] using sse2 packed doubles

[Daniël Mantione]

Op Sat, 7 Oct 2006, schreef Florian Klaempfl:

> Vincent Snijders schrieb:
> > Daniël Mantione wrote:
> > > 
> > > Op Fri, 6 Oct 2006, schreef Micha Nelissen:
> > > 
> > > 
> > > > Vincent Snijders wrote:
> > > > 
> > > You could also start an assembler implementation of the matrix unit.
> > > I suppose using it is allowed, and a Tvector2_double looks a lot like
> > > such a double2.
> > 
> > Unless the compiler somehow helps, inlining the assembler implementation
> > won't work and then the speedup might be lost again.
> 
> I started to add vector pascal like support, currently only i386/x86_64 are
> supported (no generic support). The whole (currently implemented)
> functionality is demonstrated by the following example. Please give some
> feedback if it allows benchmark speedups.

To get a large speedup, I think you should instead of making pairs of 
doubles, do the pixels in parallel. I.e. in this benchmark, a row is 3000 
pixels wide, so, make an array of 3000 doubles, and do the operation with 
arrays. With proper compiler optimization, it should be possible to 
achieve speeds close to 2 flops a clock cycle.

Daniël