egcs combine.c:simplify_shift_const

[Jeffrey A Law]

  In message <199801310023.TAA17708@jfc.>you write:
  > 
  > This patch simplifies (lshiftrt (truncate (lshiftrt))) to
  > (truncate (lshiftrt)).  This helps the multiply highpart
  > patterns in the SPARC changes I am working on.
  > 
  > Fri Jan 30 19:19:05 1998  John Carr  <jfc@mit.edu>
  > 
  > 	* combine.c (simplify_shift_const):  (lshiftrt (truncate (lshiftrt)))
  >  	is (truncate (lshiftrt)).
Thanks.  I installed the updated version you sent.

jeff