Unreviewed fix for bootstrap failure

[John David Anglin]

> Why can't we simply keep track of each replacement?  Surely it's as
> easy as incrementing one counter, and decrementing another, for each
> place where the replacement is done.

That's exactly what is done now.  The problem is the counts are not
updated when notes are created and removed.  Replacement is done much
less frequently than note creation/removal.  Thus, it seemed more
expediate to not update the counters during replacement than update
LABEL_NUSES during note creation/removal.

Do you really think there is a use for notes that indicate that a
set is equal/equivalent to a label_ref?  It might be useful on a
port that wanted to load a label_ref to a register and it was a two
or more step process.  As we apparently don't add these notes now,
I'm not convinced that it's useful.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)