[Bug rtl-optimization/55158] [4.8 Regression] segfault in schedule_region at -O3

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55158

--- Comment #18 from Steven Bosscher <steven at gcc dot gnu.org> 2012-12-04 09:56:53 UTC ---
Created attachment 28872
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28872
Updated tentative fix

(In reply to comment #16)
> I can provide IA-64 testing cycles, but I don't really have time to 
> debug the scheduler when I haven't broken it.

Sometimes you have to fix things you haven't broken.  Especially trivial
bugs like this one.  Look at all the REG_EQUAL stuff I've been trying
to fix.  I assure you I wasn't around in GCC land when in ~1992 e.g. the
optabs self-referencing REG_EQUAL notes were introduced :-)

And in this case, my tentative fix was a pointer in the right direction.
It has a rather obvious mistake in it, and anyone spending a minutes or
two looking at the patch could have spotted and resolved the mistake.

> > I'm having a look on gcc66.
> 
> Thanks.  I'm going to attach the testsuite results with the patch
> applied; all the timeouts have been introduced by it.

Attached is an updated patch.  Again untested, but that's about to change.
I'm going to test it on gcc66.