PR c++/55877

[pf3gnuchains/gcc-fork.git] / gcc / predict.c

diff --git a/gcc/predict.c b/gcc/predict.c
index a86708a..f00424c 100644 (file)
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -126,7 +126,7 @@ maybe_hot_frequency_p (int freq)
   if (node->frequency == NODE_FREQUENCY_EXECUTED_ONCE
       && freq <= (ENTRY_BLOCK_PTR->frequency * 2 / 3))
     return false;
-  if (freq < BB_FREQ_MAX / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))
+  if (freq < ENTRY_BLOCK_PTR->frequency / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))
     return false;
   return true;
 }
@@ -1790,7 +1790,8 @@ tree_estimate_probability_driver (void)
 static void
 predict_paths_for_bb (basic_block cur, basic_block bb,
                      enum br_predictor pred,
-                     enum prediction taken)
+                     enum prediction taken,
+                     bitmap visited)
 {
   edge e;
   edge_iterator ei;
@@ -1811,7 +1812,7 @@ predict_paths_for_bb (basic_block cur, basic_block bb,
        continue;
       gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb));
 
-      /* See if there is how many edge from e->src that is not abnormal
+      /* See if there is an edge from e->src that is not abnormal
         and does not lead to BB.  */
       FOR_EACH_EDGE (e2, ei2, e->src->succs)
        if (e2 != e
@@ -1824,16 +1825,20 @@ predict_paths_for_bb (basic_block cur, basic_block bb,
 
       /* If there is non-abnormal path leaving e->src, predict edge
         using predictor.  Otherwise we need to look for paths
-        leading to e->src.  */
+        leading to e->src.
+
+        The second may lead to infinite loop in the case we are predicitng
+        regions that are only reachable by abnormal edges.  We simply
+        prevent visiting given BB twice.  */
       if (found)
         predict_edge_def (e, pred, taken);
-      else
-       predict_paths_for_bb (e->src, e->src, pred, taken);
+      else if (bitmap_set_bit (visited, e->src->index))
+       predict_paths_for_bb (e->src, e->src, pred, taken, visited);
     }
   for (son = first_dom_son (CDI_POST_DOMINATORS, cur);
        son;
        son = next_dom_son (CDI_POST_DOMINATORS, son))
-    predict_paths_for_bb (son, bb, pred, taken);
+    predict_paths_for_bb (son, bb, pred, taken, visited);
 }
 
 /* Sets branch probabilities according to PREDiction and
@@ -1843,7 +1848,9 @@ static void
 predict_paths_leading_to (basic_block bb, enum br_predictor pred,
                          enum prediction taken)
 {
-  predict_paths_for_bb (bb, bb, pred, taken);
+  bitmap visited = BITMAP_ALLOC (NULL);
+  predict_paths_for_bb (bb, bb, pred, taken, visited);
+  BITMAP_FREE (visited);
 }
 
 /* Like predict_paths_leading_to but take edge instead of basic block.  */
@@ -1866,7 +1873,11 @@ predict_paths_leading_to_edge (edge e, enum br_predictor pred,
        break;
       }
   if (!has_nonloop_edge)
-    predict_paths_for_bb (bb, bb, pred, taken);
+    {
+      bitmap visited = BITMAP_ALLOC (NULL);
+      predict_paths_for_bb (bb, bb, pred, taken, visited);
+      BITMAP_FREE (visited);
+    }
   else
     predict_edge_def (e, pred, taken);
 }