[racket-dev] can we write these four lines of C in performant racket?

At Mon, 25 Jul 2011 08:05:46 -0400, Sam Tobin-Hochstadt wrote:
> On Mon, Jul 25, 2011 at 7:51 AM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> >
> > Here are some timings for 1000 iterations on 2^20-element inputs
> > (32-bit mode, Mac Book Pro 2.53 GHz):
> >
> >  C as above, gcc -02          :  1409
> >  C with indirections, gcc -O2 :  4041
> >  C as above, gcc -O0          :  6425
> >  C with indirections, gcc -O0 :  8480
> >  Racket fxvector (more direct):  8883
> >  Racket                       : 11248
> >
> > I can tweak the JIT in small ways to make a small improvement:
> >
> >  Racket with JIT tweaks       : 10670
> 
> What do the JIT tweaks do to the performance of the fxvector version?

The tweak doesn't change `fxvector-set!'.