Why can't CSE recognize const_int's in HIGH LO_SUM pair?

[law@redhat.com]

  In message < 20010910104403.E8881@redhat.com >you write:
  > On Mon, Sep 10, 2001 at 11:29:56AM -0600, law@redhat.com wrote:
  > > True.  But with the way things are currently implemented I don't think
  > > we actually lose anything on the PA by not exposing the subexpressions
  > > to gcse.  Instead of commonizing the HIGH and LO_SUM parts with other
  > > idential ones elsewhere, we end up commonizing (set (reg) (const_int))
  > 
  > Consider
  > 
  > 	(set (reg A) (const_int 0x10001))
  > 	(set (reg B) (const_int 0x10002))
  > 
  > as
  > 
  > 	(set (reg T) (const_int 0x10000))
  > 	(set (reg A) (plus (reg T) (const_int 1)))
  > 	(set (reg B) (plus (reg T) (const_int 2)))
  > 
  > Now consider A and B loaded on two different paths.  Code motion can
  > then pull T up into the dominator.
But recall that we don't do this right now on the PA due to implementation
issues.

jeff