loop invariant code motion and the jit

[Roland Westrelin]

> Roland, would it be possible to have IdealLoopTree reassociate the
> operations and then mark the AddNode to tell it to not perform
> canonicalization again?

Possibly eventhough AFAICT, current c2 code avoids that kind of
tricks. Anyway, if that was fixed one way or another, we would also need
to verify that it doesn't cause any regression so it's more work than it
may appear and in this particular case I'm not sure it's worth the trouble.

Roland.