Re: Update for cprop patch

[Jeffrey A Law <law at cygnus dot com>]

  In message <Pine.LNX.4.10.9907161109590.17496-100000@biriani.cygnus.co.uk>you
 write:
  > (Jeff, sorry for sending this twice - the first time I misspelt the
  > egcs-patches address)
  > 
  > Here's a new version of the patch.  Changes since the last one:
  >   - try to avoid entering obvious no-ops into the hash table
  >   - move the second oprs_not_set_p call into find_avail_set.  This function
  >     now guarantees that the rtx it returns can safely be substituted.
  > 
  > I left in the code to avoid infinite loops for now - I'd be happy to remove
  > it if I was convinced they can't happen anymore.
  > 
  > The patch compiles and passes make check on i686-linux with no additional
  > failures.  I also ran a benchmark which showed a very minor improvement.
  > 
  > Bernd
  > 
  > 	* gcse.c (hash_scan_set): Treat SYMBOL_REFs like CONST_INTs.
  > 	(find_avail_set): Follow chains of register-register copies.
  > 	Use oprs_not_set_p to guarantee that the returned value can be
  > 	substituted.
  > 	(cprop_jump): New function, broken out of cprop_insn.
  > 	(cprop_cc0_jump): New function.
  > 	(cprop_insn): Treat SYMBOL_REFs like CONST_INTs.
  > 	Break out new function cprop_jump and use it.
  > 	Also use cprop_cc0_jump for machines with CC0.
  > 	Don't verify the return value of find_avail_set with oprs_not_set_p.
  > 	(cprop): Don't crash if cprop_insn turned the insn into a NOTE.
I installed the SYMBOL_REF stuff.   I'm still looking at the other two
conceptual changes.  I didn't get a successful bootstrap with the other
changes, but it could have been some other transient problem in the tree.

jeff