predict.c (probably_never_executed): New function.

2013-10-02  Teresa Johnson  <tejohnson@google.com>

	* predict.c (probably_never_executed): New function.
	(probably_never_executed_bb_p): Invoke probably_never_executed.
	(probably_never_executed_edge_p): Ditto.
	* bb-reorder.c (find_rarely_executed_basic_blocks_and_crossing_edges):
	Treat profile insanities conservatively.

From-SVN: r203152

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e614e8ee7ed7e58c739ef6e3c1145636ff5e38f3..1a3aff53ed51ed42319f146d6ee846a9c1092f0b 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2013-10-02  Teresa Johnson  <tejohnson@google.com>
+
+       * predict.c (probably_never_executed): New function.
+       (probably_never_executed_bb_p): Invoke probably_never_executed.
+       (probably_never_executed_edge_p): Ditto.
+       * bb-reorder.c (find_rarely_executed_basic_blocks_and_crossing_edges):
+       Treat profile insanities conservatively.
+
 2013-10-02  John David Anglin  <danglin@gcc.gnu.org>
 
        * config.gcc (hppa*64*-*-linux*): Don't add pa/t-linux to tmake_file.

diff --git a/gcc/bb-reorder.c b/gcc/bb-reorder.c
index b89f9855e77f42d8f9ceb9dc3783aceaaaf32565..c5a42d359dcf40e35a76729a8e5e680057b256e5 100644 (file)
--- a/gcc/bb-reorder.c
+++ b/gcc/bb-reorder.c
@@ -1564,7 +1564,23 @@ find_rarely_executed_basic_blocks_and_crossing_edges (void)
   /* Mark which partition (hot/cold) each basic block belongs in.  */
   FOR_EACH_BB (bb)
     {
+      bool cold_bb = false;
+
       if (probably_never_executed_bb_p (cfun, bb))
+        {
+          /* Handle profile insanities created by upstream optimizations
+             by also checking the incoming edge weights. If there is a non-cold
+             incoming edge, conservatively prevent this block from being split
+             into the cold section.  */
+          cold_bb = true;
+          FOR_EACH_EDGE (e, ei, bb->preds)
+            if (!probably_never_executed_edge_p (cfun, e))
+              {
+                cold_bb = false;
+                break;
+              }
+        }
+      if (cold_bb)
         {
           BB_SET_PARTITION (bb, BB_COLD_PARTITION);
           cold_bb_count++;

diff --git a/gcc/predict.c b/gcc/predict.c
index 4815e75248e2b866c283ba7580a328b767109d0a..2909117ef6bd16a2f1b625f9c37b8e9f97a5004e 100644 (file)
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -226,23 +226,26 @@ maybe_hot_edge_p (edge e)
 }
 
 
-/* Return true in case BB is probably never executed.  */
 
-bool
-probably_never_executed_bb_p (struct function *fun, const_basic_block bb)
+/* Return true if profile COUNT and FREQUENCY, or function FUN static
+   node frequency reflects never being executed.  */
+   
+static bool
+probably_never_executed (struct function *fun,
+                         gcov_type count, int frequency)
 {
   gcc_checking_assert (fun);
   if (profile_status_for_function (fun) == PROFILE_READ)
     {
-      if ((bb->count * 4 + profile_info->runs / 2) / profile_info->runs > 0)
+      if ((count * 4 + profile_info->runs / 2) / profile_info->runs > 0)
        return false;
-      if (!bb->frequency)
+      if (!frequency)
        return true;
       if (!ENTRY_BLOCK_PTR->frequency)
        return false;
       if (ENTRY_BLOCK_PTR->count && ENTRY_BLOCK_PTR->count < REG_BR_PROB_BASE)
        {
-         return (RDIV (bb->frequency * ENTRY_BLOCK_PTR->count,
+         return (RDIV (frequency * ENTRY_BLOCK_PTR->count,
                        ENTRY_BLOCK_PTR->frequency)
                  < REG_BR_PROB_BASE / 4);
        }
@@ -256,19 +259,21 @@ probably_never_executed_bb_p (struct function *fun, const_basic_block bb)
 }
 
 
+/* Return true in case BB is probably never executed.  */
+
+bool
+probably_never_executed_bb_p (struct function *fun, const_basic_block bb)
+{
+  return probably_never_executed (fun, bb->count, bb->frequency);
+}
+
+
 /* Return true in case edge E is probably never executed.  */
 
 bool
 probably_never_executed_edge_p (struct function *fun, edge e)
 {
-  gcc_checking_assert (fun);
-  if (profile_info && flag_branch_probabilities)
-    return ((e->count + profile_info->runs / 2) / profile_info->runs) == 0;
-  if ((!profile_info || !flag_branch_probabilities)
-      && (cgraph_get_node (fun->decl)->frequency
-         == NODE_FREQUENCY_UNLIKELY_EXECUTED))
-    return true;
-  return false;
+  return probably_never_executed (fun, e->count, EDGE_FREQUENCY (e));
 }
 
 /* Return true if NODE should be optimized for size.  */