(optimize_reg_copy_1): After decreasing sregno's

reg_live_length, correct it if it is now obviously too small.

From-SVN: r6291

gcc/local-alloc.c

@@ -791,6 +791,11 @@ optimize_reg_copy_1 (insn, dest, src)
 	      if (sregno >= FIRST_PSEUDO_REGISTER)
 		{
 		  reg_live_length[sregno] -= length;
+		  /* reg_live_length is only an approximation after combine
+		     if sched is not run, so make sure that we still have
+		     a reasonable value.  */
+		  if (reg_live_length[sregno] < 2)
+		    reg_live_length[sregno] = 2;
 		  reg_n_calls_crossed[sregno] -= n_calls;
 		}