On Mon, Feb 13, 2012 at 12:27:35PM -0200, Alexandre Oliva wrote:
> Jakub asked to have a closer look at the problem, and I found we could
> do somewhat better. The first thing I noticed was that the problem was
> that, in each block that computed a (base+const), we created a new VALUE
> for the expression (with the same const and global base), and a new
> reverse operation.
I'm not convinced you want the
> + /* Keep VALUE equivalences around. */
> + for (l = v->locs; l; l = l->next)
> + if (GET_CODE (l->loc) == VALUE)
> + return true;
hunk in invariant_p, I'd say it should stay in preserve_only_values,
a value equivalence isn't necessarily invariant.
Otherwise the cselib.c changes look ok to me, but I don't understand why are you
removing the var-tracking.c loop. While cselib will with your changes
handle the situation better, for values that are already invariant
(guess canonical_cselib_val should be called before that loop and perhaps
instead of testing CONSTANT_P it could test invatiant_p if you rename
it to cselib_invariant_p and export) adding any reverse ops for it is really
just a waste of resources, because we have a better location already in the
list. Adding the extra loc doesn't improve it in any way.
Jakub
