Possible Front End optimization - remove entities USEd from module but not really used.

[Steve Kargl]

On Mon, Jan 07, 2013 at 07:41:29PM +0100, Toon Moene wrote:
> 
> gfortran -Ofast -g -c -fdump-fortran-original loc-nomod.f
> 

Try -fdump-tree-original.  x, y, and z do not survive
the translation of gfortran parse tree to tree-ssa form.
So, the middle/back end never see x, y, and z.

-- 
Steve