Re: patch to reduce register pressure from strength reduction

[Joern Rennecke <amylaar at cygnus dot co dot uk>]

The previous patch was not quite general enough - there is an analogous
problem for completely unrolled loops - I have no testcase for that, but
that's what code inspection tells me.

Here is the additional hunk needed:

unroll.c
*************** find_splittable_givs (bl, unroll_type, l
*** 2998,3003 ****
--- 3016,3030 ----
  				 INSN_UID (v->insn));
  		      continue;
  		    }
+ 		  if (v->same && v->same->derived_from)
+ 		    {
+ 		      /* Handle V as if the giv from which V->SAME has
+ 			 been derived has been combined with V.  */
+ 
+ 		      v->same = v->same->derived_from;
+ 		      v->new_reg = express_from (v->same, v);
+ 		    }
+ 
  		}
  	      
  	      /* Store the value of dest_reg into the insn.  This sharing