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Re: Fix PR45051


On 07/28/2010 03:46 AM, Hans-Peter Nilsson wrote:
> The SI r8/r9 ones (subreg, right) are arguably fishy, probably
> related to FRAME_POINTER_REGNUM = r8 (i.e. using an eliminable
> non-fixed register like m68k, not using a fake virtual register
> like most other ports).  I believe IRA (or at least Vlad)
> doesn't like that; see
> <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41085#c2>.
> 
> If you'd care to elaborate or confirm that your observation was
> along those lines, it'd help.  Thanks.

Huh, interesting.  Not sure about whether using a real reg as
FRAME_POINTER_REGNUM is a problem, but I'd change it since eliminating a
dummy reg into the hard frame pointer is pretty much standard practice
these days and IMO somewhat cleaner.  Also, have a look at

http://gcc.gnu.org/ml/gcc-patches/2010-07/msg00756.html

The patch won't do anything on your port due to the FRAME_POINTER_REGNUM
definition, but you could try deleting the entire if statement to see if
that makes the unnecessary reloads go away.


Bernd


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