re PR middle-end/80929 (Division with constant no more optimized to mult highpart)

	PR middle-end/80929
	* rtlanal.c (seq_cost): For non-single_set insns try to use insn_cost.

From-SVN: r255228

gcc/ChangeLog

 2017-11-29  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/80929
+	* rtlanal.c (seq_cost): For non-single_set insns try to use insn_cost.
+
 	PR target/80819
 	* config/i386/sse.md (vec_concatv2di): Remove * from (=Yr,0,*rm)
 	alternative.

gcc/rtlanal.c

@@ -5341,8 +5341,14 @@ seq_cost (const rtx_insn *seq, bool speed)
       set = single_set (seq);
       if (set)
         cost += set_rtx_cost (set, speed);
-      else
-        cost++;
+      else if (NONDEBUG_INSN_P (seq))
+	{
+	  int this_cost = insn_cost (CONST_CAST_RTX_INSN (seq), speed);
+	  if (this_cost > 0)
+	    cost += this_cost;
+	  else
+	    cost++;
+	}
     }
 
   return cost;