http://d.puremagic.com/issues/show_bug.cgi?id=7413


Don <clugd...@yahoo.com.au> changed:

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--- Comment #13 from Don <clugd...@yahoo.com.au> 2012-05-02 11:26:26 PDT ---
(In reply to comment #12)
> (In reply to comment #11)
> > Haven't done the special case optimizations for constant loading.
> 
> No problem, I'm using GDC anyway which might detect those in the back end.
> 
> An efficient implementation would certainly use at least an xor for 0
> initialisation, and the other tricks will get different mileage depending on
> the length of the pipeline surrounding. Not accessing memory is always better
> if there are pipeline cycles to soak up the latency.

The -1 trick is always worth doing, I think. Agner Fog has a nice list in his
optimisation manuals, but the only ones _always_ worth doing are the 0 and -1
integer cases, and the 0.0 floating point case (also using xor).

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