Re: Bug 14562 : copyrename & PRE

[Daniel Berlin <dberlin at dberlin dot org>]

>
> Yeah, that does seem to fix it. We aren't going to run into similar
> problems anywhere else are we? I see other places where names_match_p()
> is used that its not clear to me won't result in similar things. but
> then, i dont know PRE very well.

There's one function named reaching_def that probably has the problem, but
it isn't used and i'm going to remove it.  The rest of the uses of
names_match_p are lexical equivalence uses or unused (part of strength
reduction that probably isn't worth it to implement since i'm working on
changing algorithms), so they should be correct.

GVN-PRE won't use any of these functions (It's conceptually much
simpler), or need to match names at all, since it's value based.
I just have some speed and memory concerns about the algorithm, but i
seriously doubt it could be *slower* than PRE is now.
:)

The local PRE tree on my laptop has some speedup changes, so if you could
commit that fix, i'd much appreciate it, so that i didn't have to copy a
new tree.

I can also do it later tonight when i get home if you aren't in a rush.