[PATCH] ssa-ccp.c don't claim a node was set to a constant if it was already like that before the pass

[law@redhat.com]

  In message <200108271002.aa25646@gremlin-relay.ics.uci.edu>you write:
  > 
  > when compiling
  > 
  > int
  > test (int a, int  b)
  > {
  >   if (a > b)
  >     return 1;
  >   else
  >     return 0;
  > }
  > 
  > with -O2 -fssa -fssa-ccp the .ssaccp dump file says:
  > 
  > Register 106 now set to a constant
  > Register 111 now set to a constant
  > 
  > Well, that was the case even before ssa-ccp, so we should avoid
  > invalidating the insn and running df in this case.
  > 
  > If it's OK please apply. I don't have write access.
  > 
  > 
  > Daniel: this is the same patch I sent you last night, just against mainline
  > .
  > 
  > 
  > 2001-08-26  Dan Nicolaescu  <dann@ics.uci.edu>
  > 
  > 	* ssa-ccp.c (ssa_ccp_substitute_constants): Don't do anything if
  > 	the node was already a set to a constant. 
Thanks.  Installed.
jeff