[new-regalloc-branch]: restore usable_regs bugfix

[Denis Chertykov]

Michael Matz <matz@kde.org> writes:

> > Thu Mar 21 22:31:53 2002  Denis Chertykov  <denisc@overta.ru>
> >
> >       * ra.c (restore_conflicts_from_coalesce): Restore usable_regs before
> >       call to record_conflict.
>
> Uh oh.  I'm not sure about this.  Testcase?  Normally this is done in
> unalias_web() (called each time right after
> restore_conflicts_from_coalesce()).

Yes. I know. But, record_conflict was called from
restore_conflicts_from_coalesce before unalias_web.
record_conflict use usable_regs for right conflict recording.

> Widening usable_regs here already
> might destroy some invariants.

Please point me where usable_regs used between restore_conflicts_from_coalesce
and unalias_web. (I just not found such place, may be I was wrong.)

> As said a testcase would be able to
> convince me, right now it's somewhat late here, and I can't really think
> through it ;)

I found this bug with my own version of ra.c (trying to omit reload).

Denis.