[Haifa Scheduler] Fix latent bug in macro-fusion/instruction grouping

gcc/

	* haifa-sched.c (recompute_todo_spec): Treat SCHED_GROUP_P
	as forcing a HARD_DEP between instructions, thereby
	disallowing rewriting to break dependencies.

From-SVN: r220751

gcc/ChangeLog

+2015-02-17  James Greenhalgh  <james.greenhalgh@arm.com>
+
+	* haifa-sched.c (recompute_todo_spec): Treat SCHED_GROUP_P
+	as forcing a HARD_DEP between instructions, thereby
+	disallowing rewriting to break dependencies.
+
 2015-02-16  Jan Hubicka  <hubicka@ucw.cz>
 
 	* symtab.c (symtab_node::verify_base): Verify body_removed->!definiton

gcc/haifa-sched.c

@@ -1233,6 +1233,11 @@ recompute_todo_spec (rtx_insn *next, bool for_backtrack)
   if (!sd_lists_empty_p (next, SD_LIST_HARD_BACK))
     return HARD_DEP;
 
+  /* If NEXT is intended to sit adjacent to this instruction, we don't
+     want to try to break any dependencies.  Treat it as a HARD_DEP.  */
+  if (SCHED_GROUP_P (next))
+    return HARD_DEP;
+
   /* Now we've got NEXT with speculative deps only.
      1. Look at the deps to see what we have to do.
      2. Check if we can do 'todo'.  */