Loop optimizer issues

[law@redhat.com]

In message <200307032044.h63KiDr24360@desire.geoffk.org>, Geoff Keating writes:
 >OK.  So this is a mini-loop-optimiser working on RTL when a loop
 >optimisation pass has already been run on trees.
 >
 >In that case, I don't think you need to worry about invariant
 >libcalls.  It's not clear that you need to worry about invariant moves
 >at all; the tree-based loop optimiser should have moved all invariant
 >expressions out of the loop, even addresses of variables (they can
 >always be moved back in).
Precisely.  Similarly for CSE of libcalls and the like.

Jeff