[patch, fortran] PR 57071, some power optimizations

[Tobias Burnus]

   Am 28.04.2013 10:32, schrieb Thomas Koenig:
> the attached patch does some optimization on
> power using ishft and iand, as discussed in the PR.
>
> I have left out handling real numbers, that should be left
> to the middle-end (PR 57073).
>
> Regression-tested.  OK for trunk?

OK - thanks for the patch.

I wonder whether one should also handle:
   1**k  == 1
That should only happen (in-real-world code) due to simplifying other 
expressions but it is simple to implement.

(0**k is also possible, but it gets more complicated: 0 for k > 0, 1 for 
k == 0 and invalid for k < 0 [which one might ignore]. As this is really 
special, one can also leave the library call.)

Tobias

> 2013-04-28 Thomas Koenig  <tkoenig@gcc.gnu.org>
>
>         PR fortran/57071
>         * frontend-passes (optimize_power):  New function.
>         (optimize_op):  Use it.
>
> 2013-04-28  Thomas Koenig  <tkoenig@gcc.gnu.org>
>
>         PR fortran/57071
>         * gfortran.dg/power_3.f90:  New test.
>         * gfortran.dg/power_4.f90:  New test.