[tree-ssa] PATCH to &&/|| gimplification

[law@redhat.com]

In message <8765o1l9e4.fsf@egil.codesourcery.com>, Zack Weinberg writes:
 >Note that I'd like to see the tree->RTL converter get a lot simpler in
 >the future, which would imply that more work should be done in the
 >GIMPLE representation.  Loop rotation seems to me like something that
 >belongs done on trees.  In fact, I could argue that all the loop
 >optimizations ought to happen then, too.
Well, the mental model Richard and I hashed through a while back was
that we'd do most loop optimizations at the tree level, but that we'd
need a simplified loop optimizer to run on RTL as well.  Once we lower
to RTL there's going to be some stuff exposed for LICM and possibly 
some strength reductions.

But, yes, we want to be doing as much of the loop optimizations as
we can earlier in the compiler.


Jeff