vortex peak performance regression

[Zoltan Hidvegi]

> Zoltan,
> It looks like your patch:
> + 2001-11-30  Zoltan Hidvegi <hzoli@hzoli.2y.net>
> +
> + 	* unroll.c (unroll_loop): Correct special exit cases.
> +
> causes regression in the spec2000 tester - most importantly the vortex
> benchmark (- see www.suse.de/~aj/SPEC
> 
> It is not obvious for me why, but can you please double check
> whether the regression is unavoidable.

I have to think more about it, as I was unable to quickly produce a
testcase to show it is necessary.  But it only adds a single increment
to the loop, but that also requires an extra register, that may be
just enough to run out of registers.  I have no more time to think
about this today, I'll try to look at it tomorrow.  Which architecture
did you run the test?  It can make a difference if it has
count-regiter loop or not.

Zoli