[ tree-ssa] PRE problem

[law@redhat.com]

In message <1077304036.3169.162.camel@localhost.localdomain>, Diego Novillo wri
tes:
 >
 >See if this (untested) patch fixes your problem.  We were not calling
 >propagate_value in generate_expr_as_of_bb.  This fixes PR14153, but I
 >haven't checked other places in PRE where we may be doing the same.
Already been there, done that.  You're going to get a zillion aborts.

  1. This code needs to somehow signal to its caller that nothing useful
     can be done if may_propagate_copy returns false.

  2. Assuming may_propagate_copy returns true, then go ahead and
     call propagate_value.

I just don't know the PRE code well enough to do #1.

jeff