params.def (PARAM_MAX_SCHED_READY_INSNS): New parameter, defaulting to 100.

	* params.def (PARAM_MAX_SCHED_READY_INSNS): New parameter,
	defaulting to 100.
	* params.h (MAX_SCHED_READY_INSNS): New macro.
	* haifa-sched.c: (queue_to_ready): Re-queue insns for the next cycle
	past MAX_SCHED_READY_INSNS during the first scheduling pass.
	(schedule_block): Delay insns past MAX_SCHED_READY_INSNS in
	the ready list for 1 cycle during the first scheduling pass.
	* doc/invoke.texi (--param): New parameter max-sched-ready-insns.

From-SVN: r112936

1 files changed, 41 insertions, 3 deletions

diff --git a/gcc/haifa-sched.c b/gcc/haifa-sched.c
index ef4f4f7..6368ec6 100644
--- a/gcc/haifa-sched.c
+++ b/gcc/haifa-sched.c
@@ -1655,9 +1655,22 @@ queue_to_ready (struct ready_list *ready)
 	fprintf (sched_dump, ";;\t\tQ-->Ready: insn %s: ",
 		 (*current_sched_info->print_insn) (insn, 0));
 
-      ready_add (ready, insn, false);
-      if (sched_verbose >= 2)
-	fprintf (sched_dump, "moving to ready without stalls\n");
+      /* If the ready list is full, delay the insn for 1 cycle.
+	 See the comment in schedule_block for the rationale.  */
+      if (!reload_completed
+	  && ready->n_ready > MAX_SCHED_READY_INSNS
+	  && !SCHED_GROUP_P (insn))
+	{
+	  if (sched_verbose >= 2)
+	    fprintf (sched_dump, "requeued because ready full\n");
+	  queue_insn (insn, 1);
+	}
+      else
+	{
+	  ready_add (ready, insn, false);
+	  if (sched_verbose >= 2)
+	    fprintf (sched_dump, "moving to ready without stalls\n");
+        }
     }
   free_INSN_LIST_list (&insn_queue[q_ptr]);
 
@@ -2292,6 +2305,31 @@ schedule_block (basic_block *target_bb, int rgn_n_insns1)
      in try_ready () (which is called through init_ready_list ()).  */
   (*current_sched_info->init_ready_list) ();
 
+  /* The algorithm is O(n^2) in the number of ready insns at any given
+     time in the worst case.  Before reload we are more likely to have
+     big lists so truncate them to a reasonable size.  */
+  if (!reload_completed && ready.n_ready > MAX_SCHED_READY_INSNS)
+    {
+      ready_sort (&ready);
+
+      /* Find first free-standing insn past MAX_SCHED_READY_INSNS.  */
+      for (i = MAX_SCHED_READY_INSNS; i < ready.n_ready; i++)
+	if (!SCHED_GROUP_P (ready_element (&ready, i)))
+	  break;
+
+      if (sched_verbose >= 2)
+	{
+	  fprintf (sched_dump,
+		   ";;\t\tReady list on entry: %d insns\n", ready.n_ready);
+	  fprintf (sched_dump,
+		   ";;\t\t before reload => truncated to %d insns\n", i);
+	}
+
+      /* Delay all insns past it for 1 cycle.  */
+      while (i < ready.n_ready)
+	queue_insn (ready_remove (&ready, i), 1);
+    }
+
   /* Now we can restore basic block notes and maintain precise cfg.  */
   restore_bb_notes (*target_bb);