bb-reorder.c (find_rarely_executed_basic_blocks_and_crossing_edges): Put all BBs reachable only via paths crossing cold region to cold region.

	* bb-reorder.c (find_rarely_executed_basic_blocks_and_crossing_edges):
	Put all BBs reachable only via paths crossing cold region to cold
	region.
	* cfgrtl.c (find_bbs_reachable_by_hot_paths): New function.

From-SVN: r250417

4 files changed, 51 insertions, 38 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e5bd2bf58bc..7e87d432662 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2016-07-21  Jan Hubicka  <hubicka@ucw.cz>
+
+	* bb-reorder.c (find_rarely_executed_basic_blocks_and_crossing_edges):
+	Put all BBs reachable only via paths crossing cold region to cold
+	region.
+	* cfgrtl.c (find_bbs_reachable_by_hot_paths): New function.
+
 2016-07-21  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/81303
diff --git a/gcc/bb-reorder.c b/gcc/bb-reorder.c
index 3b7278f2be1..dc50546ab63 100644
--- a/gcc/bb-reorder.c
+++ b/gcc/bb-reorder.c
@@ -1665,6 +1665,12 @@ find_rarely_executed_basic_blocks_and_crossing_edges (void)
                                           &bbs_in_hot_partition);
       if (cold_bb_count)
         sanitize_hot_paths (false, cold_bb_count, &bbs_in_hot_partition);
+
+      hash_set <basic_block> set;
+      find_bbs_reachable_by_hot_paths (&set);
+      FOR_EACH_BB_FN (bb, cfun)
+	if (!set.contains (bb))
+	  BB_SET_PARTITION (bb, BB_COLD_PARTITION);
     }
 
   /* The format of .gcc_except_table does not allow landing pads to
diff --git a/gcc/cfgrtl.c b/gcc/cfgrtl.c
index 8c60eede0b9..58d87fe09ae 100644
--- a/gcc/cfgrtl.c
+++ b/gcc/cfgrtl.c
@@ -2282,6 +2282,29 @@ get_last_bb_insn (basic_block bb)
   return end;
 }
 
+/* Add all BBs reachable from entry via hot paths into the SET.  */
+
+void
+find_bbs_reachable_by_hot_paths (hash_set<basic_block> *set)
+{
+  auto_vec<basic_block, 64> worklist;
+
+  set->add (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+  worklist.safe_push (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+
+  while (worklist.length () > 0)
+    {
+      basic_block bb = worklist.pop ();
+      edge_iterator ei;
+      edge e;
+
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	if (BB_PARTITION (e->dest) != BB_COLD_PARTITION
+	    && !set->add (e->dest))
+	  worklist.safe_push (e->dest);
+    }
+}
+
 /* Sanity check partition hotness to ensure that basic blocks in
    the cold partition don't dominate basic blocks in the hot partition.
    If FLAG_ONLY is true, report violations as errors. Otherwise
@@ -2295,49 +2318,25 @@ find_partition_fixes (bool flag_only)
   basic_block bb;
   vec<basic_block> bbs_in_cold_partition = vNULL;
   vec<basic_block> bbs_to_fix = vNULL;
+  hash_set<basic_block> set;
 
   /* Callers check this.  */
   gcc_checking_assert (crtl->has_bb_partition);
 
-  FOR_EACH_BB_FN (bb, cfun)
-    if ((BB_PARTITION (bb) == BB_COLD_PARTITION))
-      bbs_in_cold_partition.safe_push (bb);
-
-  if (bbs_in_cold_partition.is_empty ())
-    return vNULL;
-
-  bool dom_calculated_here = !dom_info_available_p (CDI_DOMINATORS);
-
-  if (dom_calculated_here)
-    calculate_dominance_info (CDI_DOMINATORS);
-
-  while (! bbs_in_cold_partition.is_empty  ())
-    {
-      bb = bbs_in_cold_partition.pop ();
-      /* Any blocks dominated by a block in the cold section
-         must also be cold.  */
-      basic_block son;
-      for (son = first_dom_son (CDI_DOMINATORS, bb);
-           son;
-           son = next_dom_son (CDI_DOMINATORS, son))
-        {
-          /* If son is not yet cold, then mark it cold here and
-             enqueue it for further processing.  */
-          if ((BB_PARTITION (son) != BB_COLD_PARTITION))
-            {
-              if (flag_only)
-                error ("non-cold basic block %d dominated "
-                       "by a block in the cold partition (%d)", son->index, bb->index);
-              else
-                BB_SET_PARTITION (son, BB_COLD_PARTITION);
-              bbs_to_fix.safe_push (son);
-              bbs_in_cold_partition.safe_push (son);
-            }
-        }
-    }
+  find_bbs_reachable_by_hot_paths (&set);
 
-  if (dom_calculated_here)
-    free_dominance_info (CDI_DOMINATORS);
+  FOR_EACH_BB_FN (bb, cfun)
+    if (!set.contains (bb)
+	&& BB_PARTITION (bb) != BB_COLD_PARTITION)
+      {
+	if (flag_only)
+	  error ("non-cold basic block %d reachable only "
+		 "by paths crossing the cold partition", bb->index);
+	else
+	  BB_SET_PARTITION (bb, BB_COLD_PARTITION);
+	bbs_to_fix.safe_push (bb);
+	bbs_in_cold_partition.safe_push (bb);
+      }
 
   return bbs_to_fix;
 }
diff --git a/gcc/cfgrtl.h b/gcc/cfgrtl.h
index 9235b50ed66..93cb75d041e 100644
--- a/gcc/cfgrtl.h
+++ b/gcc/cfgrtl.h
@@ -54,5 +54,6 @@ extern void cfg_layout_initialize (int);
 extern void cfg_layout_finalize (void);
 extern void break_superblocks (void);
 extern void init_rtl_bb_info (basic_block);
+extern void find_bbs_reachable_by_hot_paths (hash_set <basic_block> *);
 
 #endif /* GCC_CFGRTL_H */