SSA value numbering doing better than GCSE?

[David Edelsohn]

	I do not know about this specific example, but GCC's GCSE pass
currently is hobbled.  The implementation is fine, but it does not have
enough of the dependency information to apply the optimization in all
valid instances.  I would not be surprised if the SSA pass itself is
constructing or maintaining more of the dependency information necessary
to allow the optimization to proceed in cases which GCSE currently thinks
it cannot apply them. 

David