[Bug fortran/39280] Optimizing integer power

[rguenther at suse dot de]

------- Comment #6 from rguenther at suse dot de  2010-05-10 08:41 -------
Subject: Re:  Optimizing integer power

On Sun, 9 May 2010, dfranke at gcc dot gnu dot org wrote:

> ------- Comment #4 from dfranke at gcc dot gnu dot org  2010-05-09 21:08 -------
> Situation still the same with gcc version 4.6.0 20100509 (experimental) (GCC).
> 
> (In reply to comment #1)
> > ... this asks for a POW_EXPR middle-end tree I guess.  Or you can use
> > builtins.c:expand_powi* do generate an expanded power series.
> 
> Would that be enough of a gain to be worth the effort?

If the Fortran standard allows integer powers to be expanded as
power series by default then I would say yes (at least for
non-constant power, for constant power one needs to compare
generated code - the frontend does the power series expansion
manually in this case, no?).

Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39280