patch for HJ's alpha isinff problem

[Jeffrey A Law]

  In message < 19980216170138.27223@dot.cygnus.com >you write:
  > Bother.  There's a bug in what I just sent -- the expand_compound_operation
  > bit should check the code of the operation before proceeding.  A revised
  > patch is attached.
  > 
  > 
  > r~
  > 
  > --yrj/dFKFPuw6o+aM
  > Content-Type: text/plain; charset=us-ascii
  > Content-Disposition: attachment; filename=d-ccs
  > 
  > Mon Feb 16 15:11:11 1998  Richard Henderson  <rth@cygnus.com>
  > 
  > 	* combine.c (simplify_rtx): Obey CLASS_CANNOT_CHANGE_SIZE when
  > 	simplifying a subreg of a hard reg.
  > 	(expand_compound_operation): Likewise.
  > 	(force_to_mode): Likewise.
Looks good to me.  Installed on both the release and into the mainline
sources.

jeff