[PATCH, SMS] Fix marking of SMSed loops as BB_DISABLE_SCHEDULE

[Revital Eres]

Hello,

The attach patch fixes the current marking of SMS loops to prevent
further scheduling as follows: it marks *all* the loop's bbs with
BB_DISABLE_SCHEDULE which prevents them from been scheduled later.
(with the current implementation if the loop has non empty latch then
it will be considered for scheduling based on
sched_is_disabled_for_current_region_p () in in sched-rgn.c).
It also marks the epilogue and prologue as BB_DISABLE_SCHEDULE which
was shown in my experiments as a good influence on performance as
scheduling those regions after SMS increased register pressure in some
cases.

Tested and bootstrap on all languages except java (PR50879) on
ppc64-redhat-linux, enabling SMS on loops with SC 1.

OK for mainline?

Thanks,
Revital


Changelog:

        * modulo-sched.c (generate_prolog_epilog): Mark prolog and epilog
        as BB_DISABLE_SCHEDULE.
        (mark_loop_unsched): New function.
        (sms_schedule): Call it.

Index: modulo-sched.c
===================================================================
--- modulo-sched.c      (revision 180557)
+++ modulo-sched.c      (working copy)
@@ -1173,6 +1173,7 @@ generate_prolog_epilog (partial_schedule
   /* Put the prolog on the entry edge.  */
   e = loop_preheader_edge (loop);
   split_edge_and_insert (e, get_insns ());
+  e->dest->flags |= BB_DISABLE_SCHEDULE;
 
   end_sequence ();
 
@@ -1186,9 +1187,23 @@ generate_prolog_epilog (partial_schedule
   gcc_assert (single_exit (loop));
   e = single_exit (loop);
   split_edge_and_insert (e, get_insns ());
+  e->dest->flags |= BB_DISABLE_SCHEDULE;
+
   end_sequence ();
 }
 
+/* Mark LOOP as software pipelined so the later
+   scheduling passes doesn't touch it.  */
+static void
+mark_loop_unsched (struct loop *loop)
+{
+  unsigned i;
+  basic_block *bbs = get_loop_body (loop);
+
+  for (i = 0; i < loop->num_nodes; i++)
+    bbs[i]->flags |= BB_DISABLE_SCHEDULE;
+}
+
 /* Return true if all the BBs of the loop are empty except the
    loop header.  */
 static bool
@@ -1716,7 +1731,8 @@ sms_schedule (void)
           /* Mark this loop as software pipelined so the later
             scheduling passes doesn't touch it.  */
          if (! flag_resched_modulo_sched)
-           g->bb->flags |= BB_DISABLE_SCHEDULE;
+           mark_loop_unsched (loop);
+         
          /* The life-info is not valid any more.  */
          df_set_bb_dirty (g->bb);