2007-08-17 H.J. Lu <hongjiu.lu@intel.com>

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

diff --git a/gcc/predict.c b/gcc/predict.c
index 07053ac..dbdfce4 100644 (file)
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -1,12 +1,12 @@
 /* Branch prediction routines for the GNU compiler.
 /* Branch prediction routines for the GNU compiler.

-   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005
+   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007

    Free Software Foundation, Inc.
 
 This file is part of GCC.
 
 GCC is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free
    Free Software Foundation, Inc.
 
 This file is part of GCC.
 
 GCC is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free

-Software Foundation; either version 2, or (at your option) any later
+Software Foundation; either version 3, or (at your option) any later

 version.
 
 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
 version.
 
 GCC is distributed in the hope that it will be useful, but WITHOUT ANY


@@ -15,9 +15,8 @@ FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 for more details.
 
 You should have received a copy of the GNU General Public License
 for more details.
 
 You should have received a copy of the GNU General Public License

-along with GCC; see the file COPYING.  If not, write to the Free
-Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
-02110-1301, USA.  */
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */

 
 /* References:
 
 
 /* References:
 


@@ -60,6 +59,7 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
 #include "timevar.h"
 #include "tree-scalar-evolution.h"
 #include "cfgloop.h"
 #include "timevar.h"
 #include "tree-scalar-evolution.h"
 #include "cfgloop.h"

+#include "pointer-set.h"

 
 /* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE,
                   1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX.  */
 
 /* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE,
                   1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX.  */


@@ -74,14 +74,10 @@ static sreal real_zero, real_one, real_almost_one, real_br_prob_base,
 
 static void combine_predictions_for_insn (rtx, basic_block);
 static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int);
 
 static void combine_predictions_for_insn (rtx, basic_block);
 static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int);

-static void estimate_loops_at_level (struct loop *, bitmap);
-static void propagate_freq (struct loop *, bitmap);
-static void estimate_bb_frequencies (struct loops *);

 static void predict_paths_leading_to (basic_block, int *, enum br_predictor, enum prediction);
 static void predict_paths_leading_to (basic_block, int *, enum br_predictor, enum prediction);

-static bool last_basic_block_p (basic_block);

 static void compute_function_frequency (void);
 static void choose_function_section (void);
 static void compute_function_frequency (void);
 static void choose_function_section (void);

-static bool can_predict_insn_p (rtx);
+static bool can_predict_insn_p (const_rtx);

 
 /* Information we hold about each branch predictor.
    Filled using information from predict.def.  */
 
 /* Information we hold about each branch predictor.
    Filled using information from predict.def.  */


@@ -115,12 +111,19 @@ static const struct predictor_info predictor_info[]= {
    for maximal performance.  */
 
 bool
    for maximal performance.  */
 
 bool

-maybe_hot_bb_p (basic_block bb)
+maybe_hot_bb_p (const_basic_block bb)

 {
   if (profile_info && flag_branch_probabilities
       && (bb->count
          < profile_info->sum_max / PARAM_VALUE (HOT_BB_COUNT_FRACTION)))
     return false;
 {
   if (profile_info && flag_branch_probabilities
       && (bb->count
          < profile_info->sum_max / PARAM_VALUE (HOT_BB_COUNT_FRACTION)))
     return false;

+  if (!profile_info || !flag_branch_probabilities)
+    {
+      if (cfun->function_frequency == FUNCTION_FREQUENCY_UNLIKELY_EXECUTED)
+        return false;
+      if (cfun->function_frequency == FUNCTION_FREQUENCY_HOT)
+        return true;
+    }

   if (bb->frequency < BB_FREQ_MAX / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))
     return false;
   return true;
   if (bb->frequency < BB_FREQ_MAX / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))
     return false;
   return true;


@@ -129,12 +132,15 @@ maybe_hot_bb_p (basic_block bb)
 /* Return true in case BB is cold and should be optimized for size.  */
 
 bool
 /* Return true in case BB is cold and should be optimized for size.  */
 
 bool

-probably_cold_bb_p (basic_block bb)
+probably_cold_bb_p (const_basic_block bb)

 {
   if (profile_info && flag_branch_probabilities
       && (bb->count
          < profile_info->sum_max / PARAM_VALUE (HOT_BB_COUNT_FRACTION)))
     return true;
 {
   if (profile_info && flag_branch_probabilities
       && (bb->count
          < profile_info->sum_max / PARAM_VALUE (HOT_BB_COUNT_FRACTION)))
     return true;

+  if ((!profile_info || !flag_branch_probabilities)
+      && cfun->function_frequency == FUNCTION_FREQUENCY_UNLIKELY_EXECUTED)
+    return true;

   if (bb->frequency < BB_FREQ_MAX / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))
     return true;
   return false;
   if (bb->frequency < BB_FREQ_MAX / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))
     return true;
   return false;


@@ -142,10 +148,13 @@ probably_cold_bb_p (basic_block bb)
 
 /* Return true in case BB is probably never executed.  */
 bool
 
 /* Return true in case BB is probably never executed.  */
 bool

-probably_never_executed_bb_p (basic_block bb)
+probably_never_executed_bb_p (const_basic_block bb)

 {
   if (profile_info && flag_branch_probabilities)
     return ((bb->count + profile_info->runs / 2) / profile_info->runs) == 0;
 {
   if (profile_info && flag_branch_probabilities)
     return ((bb->count + profile_info->runs / 2) / profile_info->runs) == 0;

+  if ((!profile_info || !flag_branch_probabilities)
+      && cfun->function_frequency == FUNCTION_FREQUENCY_UNLIKELY_EXECUTED)
+    return true;

   return false;
 }
 
   return false;
 }
 


@@ -165,6 +174,11 @@ rtl_predicted_by_p (basic_block bb, enum br_predictor predictor)
   return false;
 }
 
   return false;
 }
 

+/* This map contains for a basic block the list of predictions for the
+   outgoing edges.  */
+
+static struct pointer_map_t *bb_predictions;
+

 /* Return true if the one of outgoing edges is already predicted by
    PREDICTOR.  */
 
 /* Return true if the one of outgoing edges is already predicted by
    PREDICTOR.  */
 


@@ -172,12 +186,56 @@ bool
 tree_predicted_by_p (basic_block bb, enum br_predictor predictor)
 {
   struct edge_prediction *i;
 tree_predicted_by_p (basic_block bb, enum br_predictor predictor)
 {
   struct edge_prediction *i;

-  for (i = bb->predictions; i; i = i->ep_next)
+  void **preds = pointer_map_contains (bb_predictions, bb);
+
+  if (!preds)
+    return false;
+  
+  for (i = *preds; i; i = i->ep_next)

     if (i->ep_predictor == predictor)
       return true;
   return false;
 }
 
     if (i->ep_predictor == predictor)
       return true;
   return false;
 }
 

+/* Return true when the probability of edge is reliable.
+  
+   The profile guessing code is good at predicting branch outcome (ie.
+   taken/not taken), that is predicted right slightly over 75% of time.
+   It is however notoriously poor on predicting the probability itself.
+   In general the profile appear a lot flatter (with probabilities closer
+   to 50%) than the reality so it is bad idea to use it to drive optimization
+   such as those disabling dynamic branch prediction for well predictable
+   branches.
+
+   There are two exceptions - edges leading to noreturn edges and edges
+   predicted by number of iterations heuristics are predicted well.  This macro
+   should be able to distinguish those, but at the moment it simply check for
+   noreturn heuristic that is only one giving probability over 99% or bellow
+   1%.  In future we might want to propagate reliability information across the
+   CFG if we find this information useful on multiple places.   */
+static bool
+probability_reliable_p (int prob)
+{
+  return (profile_status == PROFILE_READ
+         || (profile_status == PROFILE_GUESSED
+             && (prob <= HITRATE (1) || prob >= HITRATE (99))));
+}
+
+/* Same predicate as above, working on edges.  */
+bool
+edge_probability_reliable_p (const_edge e)
+{
+  return probability_reliable_p (e->probability);
+}
+
+/* Same predicate as edge_probability_reliable_p, working on notes.  */
+bool
+br_prob_note_reliable_p (const_rtx note)
+{
+  gcc_assert (REG_NOTE_KIND (note) == REG_BR_PROB);
+  return probability_reliable_p (INTVAL (XEXP (note, 0)));
+}
+

 static void
 predict_insn (rtx insn, enum br_predictor predictor, int probability)
 {
 static void
 predict_insn (rtx insn, enum br_predictor predictor, int probability)
 {


@@ -235,10 +293,11 @@ tree_predict_edge (edge e, enum br_predictor predictor, int probability)
   if ((e->src != ENTRY_BLOCK_PTR && EDGE_COUNT (e->src->succs) > 1)
       && flag_guess_branch_prob && optimize)
     {
   if ((e->src != ENTRY_BLOCK_PTR && EDGE_COUNT (e->src->succs) > 1)
       && flag_guess_branch_prob && optimize)
     {

-      struct edge_prediction *i = ggc_alloc (sizeof (struct edge_prediction));
+      struct edge_prediction *i = XNEW (struct edge_prediction);
+      void **preds = pointer_map_insert (bb_predictions, e->src);

 
 

-      i->ep_next = e->src->predictions;
-      e->src->predictions = i;
+      i->ep_next = *preds;
+      *preds = i;

       i->ep_probability = probability;
       i->ep_predictor = predictor;
       i->ep_edge = e;
       i->ep_probability = probability;
       i->ep_predictor = predictor;
       i->ep_edge = e;


@@ -250,24 +309,56 @@ tree_predict_edge (edge e, enum br_predictor predictor, int probability)
 void
 remove_predictions_associated_with_edge (edge e)
 {
 void
 remove_predictions_associated_with_edge (edge e)
 {

-  if (e->src->predictions)
+  void **preds;
+  
+  if (!bb_predictions)
+    return;
+
+  preds = pointer_map_contains (bb_predictions, e->src);
+
+  if (preds)

     {
     {

-      struct edge_prediction **prediction = &e->src->predictions;
+      struct edge_prediction **prediction = (struct edge_prediction **) preds;
+      struct edge_prediction *next;
+

       while (*prediction)
        {
          if ((*prediction)->ep_edge == e)
       while (*prediction)
        {
          if ((*prediction)->ep_edge == e)

-           *prediction = (*prediction)->ep_next;
+           {
+             next = (*prediction)->ep_next;
+             free (*prediction);
+             *prediction = next;
+           }

          else
            prediction = &((*prediction)->ep_next);
        }
     }
 }
 
          else
            prediction = &((*prediction)->ep_next);
        }
     }
 }
 

+/* Clears the list of predictions stored for BB.  */
+
+static void
+clear_bb_predictions (basic_block bb)
+{
+  void **preds = pointer_map_contains (bb_predictions, bb);
+  struct edge_prediction *pred, *next;
+
+  if (!preds)
+    return;
+
+  for (pred = *preds; pred; pred = next)
+    {
+      next = pred->ep_next;
+      free (pred);
+    }
+  *preds = NULL;
+}
+

 /* Return true when we can store prediction on insn INSN.
    At the moment we represent predictions only on conditional
    jumps, not at computed jump or other complicated cases.  */
 static bool
 /* Return true when we can store prediction on insn INSN.
    At the moment we represent predictions only on conditional
    jumps, not at computed jump or other complicated cases.  */
 static bool

-can_predict_insn_p (rtx insn)
+can_predict_insn_p (const_rtx insn)

 {
   return (JUMP_P (insn)
          && any_condjump_p (insn)
 {
   return (JUMP_P (insn)
          && any_condjump_p (insn)


@@ -478,7 +569,7 @@ combine_predictions_for_insn (rtx insn, basic_block bb)
    Remove now useless prediction entries.  */
 
 static void
    Remove now useless prediction entries.  */
 
 static void

-combine_predictions_for_bb (FILE *file, basic_block bb)
+combine_predictions_for_bb (basic_block bb)

 {
   int best_probability = PROB_EVEN;
   int best_predictor = END_PREDICTORS;
 {
   int best_probability = PROB_EVEN;
   int best_predictor = END_PREDICTORS;


@@ -490,6 +581,7 @@ combine_predictions_for_bb (FILE *file, basic_block bb)
   int nedges = 0;
   edge e, first = NULL, second = NULL;
   edge_iterator ei;
   int nedges = 0;
   edge e, first = NULL, second = NULL;
   edge_iterator ei;

+  void **preds;

 
   FOR_EACH_EDGE (e, ei, bb->succs)
     if (!(e->flags & (EDGE_EH | EDGE_FAKE)))
 
   FOR_EACH_EDGE (e, ei, bb->succs)
     if (!(e->flags & (EDGE_EH | EDGE_FAKE)))


@@ -511,41 +603,46 @@ combine_predictions_for_bb (FILE *file, basic_block bb)
     {
       if (!bb->count)
        set_even_probabilities (bb);
     {
       if (!bb->count)
        set_even_probabilities (bb);

-      bb->predictions = NULL;
-      if (file)
-       fprintf (file, "%i edges in bb %i predicted to even probabilities\n",
+      clear_bb_predictions (bb);
+      if (dump_file)
+       fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n",

                 nedges, bb->index);
       return;
     }
 
                 nedges, bb->index);
       return;
     }
 

-  if (file)
-    fprintf (file, "Predictions for bb %i\n", bb->index);
+  if (dump_file)
+    fprintf (dump_file, "Predictions for bb %i\n", bb->index);

 
 

-  /* We implement "first match" heuristics and use probability guessed
-     by predictor with smallest index.  */
-  for (pred = bb->predictions; pred; pred = pred->ep_next)
+  preds = pointer_map_contains (bb_predictions, bb);
+  if (preds)

     {
     {

-      int predictor = pred->ep_predictor;
-      int probability = pred->ep_probability;
+      /* We implement "first match" heuristics and use probability guessed
+        by predictor with smallest index.  */
+      for (pred = *preds; pred; pred = pred->ep_next)
+       {
+         int predictor = pred->ep_predictor;
+         int probability = pred->ep_probability;

 
 

-      if (pred->ep_edge != first)
-       probability = REG_BR_PROB_BASE - probability;
+         if (pred->ep_edge != first)
+           probability = REG_BR_PROB_BASE - probability;

 
 

-      found = true;
-      if (best_predictor > predictor)
-       best_probability = probability, best_predictor = predictor;
+         found = true;
+         if (best_predictor > predictor)
+           best_probability = probability, best_predictor = predictor;

 
 

-      d = (combined_probability * probability
-          + (REG_BR_PROB_BASE - combined_probability)
-          * (REG_BR_PROB_BASE - probability));
+         d = (combined_probability * probability
+              + (REG_BR_PROB_BASE - combined_probability)
+              * (REG_BR_PROB_BASE - probability));

 
 

-      /* Use FP math to avoid overflows of 32bit integers.  */
-      if (d == 0)
-       /* If one probability is 0% and one 100%, avoid division by zero.  */
-       combined_probability = REG_BR_PROB_BASE / 2;
-      else
-       combined_probability = (((double) combined_probability) * probability
-                               * REG_BR_PROB_BASE / d + 0.5);
+         /* Use FP math to avoid overflows of 32bit integers.  */
+         if (d == 0)
+           /* If one probability is 0% and one 100%, avoid division by zero.  */
+           combined_probability = REG_BR_PROB_BASE / 2;
+         else
+           combined_probability = (((double) combined_probability)
+                                   * probability
+                                   * REG_BR_PROB_BASE / d + 0.5);
+       }

     }
 
   /* Decide which heuristic to use.  In case we didn't match anything,
     }
 
   /* Decide which heuristic to use.  In case we didn't match anything,


@@ -556,30 +653,33 @@ combine_predictions_for_bb (FILE *file, basic_block bb)
     first_match = true;
 
   if (!found)
     first_match = true;
 
   if (!found)

-    dump_prediction (file, PRED_NO_PREDICTION, combined_probability, bb, true);
+    dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true);

   else
     {
   else
     {

-      dump_prediction (file, PRED_DS_THEORY, combined_probability, bb,
+      dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb,

                       !first_match);
                       !first_match);

-      dump_prediction (file, PRED_FIRST_MATCH, best_probability, bb,
+      dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb,

                       first_match);
     }
 
   if (first_match)
     combined_probability = best_probability;
                       first_match);
     }
 
   if (first_match)
     combined_probability = best_probability;

-  dump_prediction (file, PRED_COMBINED, combined_probability, bb, true);
+  dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true);

 
 

-  for (pred = bb->predictions; pred; pred = pred->ep_next)
+  if (preds)

     {
     {

-      int predictor = pred->ep_predictor;
-      int probability = pred->ep_probability;
+      for (pred = *preds; pred; pred = pred->ep_next)
+       {
+         int predictor = pred->ep_predictor;
+         int probability = pred->ep_probability;

 
 

-      if (pred->ep_edge != EDGE_SUCC (bb, 0))
-       probability = REG_BR_PROB_BASE - probability;
-      dump_prediction (file, predictor, probability, bb,
-                      !first_match || best_predictor == predictor);
+         if (pred->ep_edge != EDGE_SUCC (bb, 0))
+           probability = REG_BR_PROB_BASE - probability;
+         dump_prediction (dump_file, predictor, probability, bb,
+                          !first_match || best_predictor == predictor);
+       }

     }
     }

-  bb->predictions = NULL;
+  clear_bb_predictions (bb);

 
   if (!bb->count)
     {
 
   if (!bb->count)
     {


@@ -588,90 +688,71 @@ combine_predictions_for_bb (FILE *file, basic_block bb)
     }
 }
 
     }
 }
 

-/* Predict edge probabilities by exploiting loop structure.
-   When RTLSIMPLELOOPS is set, attempt to count number of iterations by analyzing
-   RTL otherwise use tree based approach.  */
+/* Predict edge probabilities by exploiting loop structure.  */
+

 static void
 static void

-predict_loops (struct loops *loops_info, bool rtlsimpleloops)
+predict_loops (void)

 {
 {

-  unsigned i;
+  loop_iterator li;
+  struct loop *loop;

 
 

-  if (!rtlsimpleloops)
-    scev_initialize (loops_info);
+  scev_initialize ();

 
   /* Try to predict out blocks in a loop that are not part of a
      natural loop.  */
 
   /* Try to predict out blocks in a loop that are not part of a
      natural loop.  */

-  for (i = 1; i < loops_info->num; i++)
+  FOR_EACH_LOOP (li, loop, 0)

     {
       basic_block bb, *bbs;
     {
       basic_block bb, *bbs;

-      unsigned j;
-      unsigned n_exits;
-      struct loop *loop = loops_info->parray[i];
-      struct niter_desc desc;
-      unsigned HOST_WIDE_INT niter;
-      edge *exits;
+      unsigned j, n_exits;
+      VEC (edge, heap) *exits;
+      struct tree_niter_desc niter_desc;
+      edge ex;

 
 

-      exits = get_loop_exit_edges (loop, &n_exits);
+      exits = get_loop_exit_edges (loop);
+      n_exits = VEC_length (edge, exits);

 
 

-      if (rtlsimpleloops)
+      for (j = 0; VEC_iterate (edge, exits, j, ex); j++)

        {
        {

-         iv_analysis_loop_init (loop);
-         find_simple_exit (loop, &desc);
-
-         if (desc.simple_p && desc.const_iter)
+         tree niter = NULL;
+         HOST_WIDE_INT nitercst;
+         int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS);
+         int probability;
+         enum br_predictor predictor;
+
+         if (number_of_iterations_exit (loop, ex, &niter_desc, false))
+           niter = niter_desc.niter;
+         if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST)
+           niter = loop_niter_by_eval (loop, ex);
+
+         if (TREE_CODE (niter) == INTEGER_CST)

            {
            {

-             int prob;
-             niter = desc.niter + 1;
-             if (niter == 0)        /* We might overflow here.  */
-               niter = desc.niter;
-             if (niter
-                 > (unsigned int) PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS))
-               niter = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS);
-
-             prob = (REG_BR_PROB_BASE
-                     - (REG_BR_PROB_BASE + niter /2) / niter);
-             /* Branch prediction algorithm gives 0 frequency for everything
-                after the end of loop for loop having 0 probability to finish.  */
-             if (prob == REG_BR_PROB_BASE)
-               prob = REG_BR_PROB_BASE - 1;
-             predict_edge (desc.in_edge, PRED_LOOP_ITERATIONS,
-                           prob);
+             if (host_integerp (niter, 1)
+                 && compare_tree_int (niter, max-1) == -1)
+               nitercst = tree_low_cst (niter, 1) + 1;
+             else
+               nitercst = max;
+             predictor = PRED_LOOP_ITERATIONS;

            }
            }

-       }
-      else
-       {
-         struct tree_niter_desc niter_desc;
-
-         for (j = 0; j < n_exits; j++)
+         /* If we have just one exit and we can derive some information about
+            the number of iterations of the loop from the statements inside
+            the loop, use it to predict this exit.  */
+         else if (n_exits == 1)

            {
            {

-             tree niter = NULL;
-
-             if (number_of_iterations_exit (loop, exits[j], &niter_desc, false))
-               niter = niter_desc.niter;
-             if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST)
-               niter = loop_niter_by_eval (loop, exits[j]);
-
-             if (TREE_CODE (niter) == INTEGER_CST)
-               {
-                 int probability;
-                 int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS);
-                 if (host_integerp (niter, 1)
-                     && tree_int_cst_lt (niter,
-                                         build_int_cstu (NULL_TREE, max - 1)))
-                   {
-                     HOST_WIDE_INT nitercst = tree_low_cst (niter, 1) + 1;
-                     probability = ((REG_BR_PROB_BASE + nitercst / 2)
-                                    / nitercst);
-                   }
-                 else
-                   probability = ((REG_BR_PROB_BASE + max / 2) / max);
+             nitercst = estimated_loop_iterations_int (loop, false);
+             if (nitercst < 0)
+               continue;
+             if (nitercst > max)
+               nitercst = max;

 
 

-                 predict_edge (exits[j], PRED_LOOP_ITERATIONS, probability);
-               }
+             predictor = PRED_LOOP_ITERATIONS_GUESSED;

            }
            }

+         else
+           continue;

 
 

+         probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst);
+         predict_edge (ex, predictor, probability);

        }
        }

-      free (exits);
+      VEC_free (edge, heap, exits);

 
       bbs = get_loop_body (loop);
 
 
       bbs = get_loop_body (loop);
 


@@ -687,8 +768,7 @@ predict_loops (struct loops *loops_info, bool rtlsimpleloops)
             statements construct loops via "non-loop" constructs
             in the source language and are better to be handled
             separately.  */
             statements construct loops via "non-loop" constructs
             in the source language and are better to be handled
             separately.  */

-         if ((rtlsimpleloops && !can_predict_insn_p (BB_END (bb)))
-             || predicted_by_p (bb, PRED_CONTINUE))
+         if (predicted_by_p (bb, PRED_CONTINUE))

            continue;
 
          /* Loop branch heuristics - predict an edge back to a
            continue;
 
          /* Loop branch heuristics - predict an edge back to a


@@ -705,26 +785,43 @@ predict_loops (struct loops *loops_info, bool rtlsimpleloops)
 
          /* Loop exit heuristics - predict an edge exiting the loop if the
             conditional has no loop header successors as not taken.  */
 
          /* Loop exit heuristics - predict an edge exiting the loop if the
             conditional has no loop header successors as not taken.  */

-         if (!header_found)
-           FOR_EACH_EDGE (e, ei, bb->succs)
-             if (e->dest->index < NUM_FIXED_BLOCKS
-                 || !flow_bb_inside_loop_p (loop, e->dest))
-               predict_edge
-                 (e, PRED_LOOP_EXIT,
-                  (REG_BR_PROB_BASE
-                   - predictor_info [(int) PRED_LOOP_EXIT].hitrate)
-                  / n_exits);
+         if (!header_found
+             /* If we already used more reliable loop exit predictors, do not
+                bother with PRED_LOOP_EXIT.  */
+             && !predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED)
+             && !predicted_by_p (bb, PRED_LOOP_ITERATIONS))
+           {
+             /* For loop with many exits we don't want to predict all exits
+                with the pretty large probability, because if all exits are
+                considered in row, the loop would be predicted to iterate
+                almost never.  The code to divide probability by number of
+                exits is very rough.  It should compute the number of exits
+                taken in each patch through function (not the overall number
+                of exits that might be a lot higher for loops with wide switch
+                statements in them) and compute n-th square root.
+
+                We limit the minimal probability by 2% to avoid
+                EDGE_PROBABILITY_RELIABLE from trusting the branch prediction
+                as this was causing regression in perl benchmark containing such
+                a wide loop.  */
+               
+             int probability = ((REG_BR_PROB_BASE
+                                 - predictor_info [(int) PRED_LOOP_EXIT].hitrate)
+                                / n_exits);
+             if (probability < HITRATE (2))
+               probability = HITRATE (2);
+             FOR_EACH_EDGE (e, ei, bb->succs)
+               if (e->dest->index < NUM_FIXED_BLOCKS
+                   || !flow_bb_inside_loop_p (loop, e->dest))
+                 predict_edge (e, PRED_LOOP_EXIT, probability);
+           }

        }
       
       /* Free basic blocks from get_loop_body.  */
       free (bbs);
     }
 
        }
       
       /* Free basic blocks from get_loop_body.  */
       free (bbs);
     }
 

-  if (!rtlsimpleloops)
-    {
-      scev_finalize ();
-      current_loops = NULL;
-    }
+  scev_finalize ();

 }
 
 /* Attempt to predict probabilities of BB outgoing edges using local
 }
 
 /* Attempt to predict probabilities of BB outgoing edges using local


@@ -826,85 +923,6 @@ bb_estimate_probability_locally (basic_block bb)
       }
 }
 
       }
 }
 

-/* Statically estimate the probability that a branch will be taken and produce
-   estimated profile.  When profile feedback is present never executed portions
-   of function gets estimated.  */
-
-void
-estimate_probability (struct loops *loops_info)
-{
-  basic_block bb;
-
-  connect_infinite_loops_to_exit ();
-  calculate_dominance_info (CDI_DOMINATORS);
-  calculate_dominance_info (CDI_POST_DOMINATORS);
-
-  predict_loops (loops_info, true);
-
-  iv_analysis_done ();
-
-  /* Attempt to predict conditional jumps using a number of heuristics.  */
-  FOR_EACH_BB (bb)
-    {
-      rtx last_insn = BB_END (bb);
-      edge e;
-      edge_iterator ei;
-
-      if (! can_predict_insn_p (last_insn))
-       continue;
-
-      FOR_EACH_EDGE (e, ei, bb->succs)
-       {
-         /* Predict early returns to be probable, as we've already taken
-            care for error returns and other are often used for fast paths
-            trought function.  */
-         if ((e->dest == EXIT_BLOCK_PTR
-              || (single_succ_p (e->dest)
-                  && single_succ (e->dest) == EXIT_BLOCK_PTR))
-              && !predicted_by_p (bb, PRED_NULL_RETURN)
-              && !predicted_by_p (bb, PRED_CONST_RETURN)
-              && !predicted_by_p (bb, PRED_NEGATIVE_RETURN)
-              && !last_basic_block_p (e->dest))
-           predict_edge_def (e, PRED_EARLY_RETURN, TAKEN);
-
-         /* Look for block we are guarding (i.e. we dominate it,
-            but it doesn't postdominate us).  */
-         if (e->dest != EXIT_BLOCK_PTR && e->dest != bb
-             && dominated_by_p (CDI_DOMINATORS, e->dest, e->src)
-             && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest))
-           {
-             rtx insn;
-
-             /* The call heuristic claims that a guarded function call
-                is improbable.  This is because such calls are often used
-                to signal exceptional situations such as printing error
-                messages.  */
-             for (insn = BB_HEAD (e->dest); insn != NEXT_INSN (BB_END (e->dest));
-                  insn = NEXT_INSN (insn))
-               if (CALL_P (insn)
-                   /* Constant and pure calls are hardly used to signalize
-                      something exceptional.  */
-                   && ! CONST_OR_PURE_CALL_P (insn))
-                 {
-                   predict_edge_def (e, PRED_CALL, NOT_TAKEN);
-                   break;
-                 }
-           }
-       }
-      bb_estimate_probability_locally (bb);
-    }
-
-  /* Attach the combined probability to each conditional jump.  */
-  FOR_EACH_BB (bb)
-    combine_predictions_for_insn (BB_END (bb), bb);
-
-  remove_fake_edges ();
-  estimate_bb_frequencies (loops_info);
-  free_dominance_info (CDI_POST_DOMINATORS);
-  if (profile_status == PROFILE_ABSENT)
-    profile_status = PROFILE_GUESSED;
-}
-

 /* Set edge->probability for each successor edge of BB.  */
 void
 guess_outgoing_edge_probabilities (basic_block bb)
 /* Set edge->probability for each successor edge of BB.  */
 void
 guess_outgoing_edge_probabilities (basic_block bb)


@@ -965,9 +983,10 @@ expr_expected_value (tree expr, bitmap visited)
            }
          return val;
        }
            }
          return val;
        }

-      if (TREE_CODE (def) != MODIFY_EXPR || TREE_OPERAND (def, 0) != expr)
+      if (TREE_CODE (def) != GIMPLE_MODIFY_STMT
+         || GIMPLE_STMT_OPERAND (def, 0) != expr)

        return NULL;
        return NULL;

-      return expr_expected_value (TREE_OPERAND (def, 1), visited);
+      return expr_expected_value (GIMPLE_STMT_OPERAND (def, 1), visited);

     }
   else if (TREE_CODE (expr) == CALL_EXPR)
     {
     }
   else if (TREE_CODE (expr) == CALL_EXPR)
     {


@@ -977,16 +996,14 @@ expr_expected_value (tree expr, bitmap visited)
       if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
          && DECL_FUNCTION_CODE (decl) == BUILT_IN_EXPECT)
        {
       if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
          && DECL_FUNCTION_CODE (decl) == BUILT_IN_EXPECT)
        {

-         tree arglist = TREE_OPERAND (expr, 1);

          tree val;
 
          tree val;
 

-         if (arglist == NULL_TREE
-             || TREE_CHAIN (arglist) == NULL_TREE)
-           return NULL; 
-         val = TREE_VALUE (TREE_CHAIN (TREE_OPERAND (expr, 1)));
+         if (call_expr_nargs (expr) != 2)
+           return NULL;
+         val = CALL_EXPR_ARG (expr, 0);

          if (TREE_CONSTANT (val))
            return val;
          if (TREE_CONSTANT (val))
            return val;

-         return TREE_VALUE (TREE_CHAIN (TREE_OPERAND (expr, 1)));
+         return CALL_EXPR_ARG (expr, 1);

        }
     }
   if (BINARY_CLASS_P (expr) || COMPARISON_CLASS_P (expr))
        }
     }
   if (BINARY_CLASS_P (expr) || COMPARISON_CLASS_P (expr))


@@ -1029,17 +1046,17 @@ strip_builtin_expect (void)
        {
          tree stmt = bsi_stmt (bi);
          tree fndecl;
        {
          tree stmt = bsi_stmt (bi);
          tree fndecl;

-         tree arglist;
+         tree call;

 
 

-         if (TREE_CODE (stmt) == MODIFY_EXPR
-             && TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR
-             && (fndecl = get_callee_fndecl (TREE_OPERAND (stmt, 1)))
+         if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+             && (call = GIMPLE_STMT_OPERAND (stmt, 1))
+             && TREE_CODE (call) == CALL_EXPR
+             && (fndecl = get_callee_fndecl (call))

              && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
              && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT
              && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
              && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT

-             && (arglist = TREE_OPERAND (TREE_OPERAND (stmt, 1), 1))
-             && TREE_CHAIN (arglist))
+             && call_expr_nargs (call) == 2)

            {
            {

-             TREE_OPERAND (stmt, 1) = TREE_VALUE (arglist);
+             GIMPLE_STMT_OPERAND (stmt, 1) = CALL_EXPR_ARG (call, 0);

              update_stmt (stmt);
            }
        }
              update_stmt (stmt);
            }
        }


@@ -1199,7 +1216,7 @@ return_prediction (tree val, enum prediction *prediction)
          && (!integer_zerop (val) && !integer_onep (val)))
        {
          *prediction = TAKEN;
          && (!integer_zerop (val) && !integer_onep (val)))
        {
          *prediction = TAKEN;

-         return PRED_NEGATIVE_RETURN;
+         return PRED_CONST_RETURN;

        }
     }
   return PRED_NO_PREDICTION;
        }
     }
   return PRED_NO_PREDICTION;


@@ -1222,7 +1239,8 @@ apply_return_prediction (int *heads)
   FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
     {
       return_stmt = last_stmt (e->src);
   FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
     {
       return_stmt = last_stmt (e->src);

-      if (TREE_CODE (return_stmt) == RETURN_EXPR)
+      if (return_stmt
+         && TREE_CODE (return_stmt) == RETURN_EXPR)

        break;
     }
   if (!e)
        break;
     }
   if (!e)


@@ -1230,8 +1248,8 @@ apply_return_prediction (int *heads)
   return_val = TREE_OPERAND (return_stmt, 0);
   if (!return_val)
     return;
   return_val = TREE_OPERAND (return_stmt, 0);
   if (!return_val)
     return;

-  if (TREE_CODE (return_val) == MODIFY_EXPR)
-    return_val = TREE_OPERAND (return_val, 1);
+  if (TREE_CODE (return_val) == GIMPLE_MODIFY_STMT)
+    return_val = GIMPLE_STMT_OPERAND (return_val, 1);

   if (TREE_CODE (return_val) != SSA_NAME
       || !SSA_NAME_DEF_STMT (return_val)
       || TREE_CODE (SSA_NAME_DEF_STMT (return_val)) != PHI_NODE)
   if (TREE_CODE (return_val) != SSA_NAME
       || !SSA_NAME_DEF_STMT (return_val)
       || TREE_CODE (SSA_NAME_DEF_STMT (return_val)) != PHI_NODE)


@@ -1270,8 +1288,7 @@ tree_bb_level_predictions (void)
   basic_block bb;
   int *heads;
 
   basic_block bb;
   int *heads;
 

-  heads = XNEWVEC (int, last_basic_block);
-  memset (heads, ENTRY_BLOCK, sizeof (int) * last_basic_block);
+  heads = XCNEWVEC (int, last_basic_block);

   heads[ENTRY_BLOCK_PTR->next_bb->index] = last_basic_block;
 
   apply_return_prediction (heads);
   heads[ENTRY_BLOCK_PTR->next_bb->index] = last_basic_block;
 
   apply_return_prediction (heads);


@@ -1283,12 +1300,13 @@ tree_bb_level_predictions (void)
       for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
        {
          tree stmt = bsi_stmt (bsi);
       for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
        {
          tree stmt = bsi_stmt (bsi);

+         tree decl;

          switch (TREE_CODE (stmt))
            {
          switch (TREE_CODE (stmt))
            {

-             case MODIFY_EXPR:
-               if (TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR)
+             case GIMPLE_MODIFY_STMT:
+               if (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == CALL_EXPR)

                  {
                  {

-                   stmt = TREE_OPERAND (stmt, 1);
+                   stmt = GIMPLE_STMT_OPERAND (stmt, 1);

                    goto call_expr;
                  }
                break;
                    goto call_expr;
                  }
                break;


@@ -1297,6 +1315,12 @@ call_expr:;
                if (call_expr_flags (stmt) & ECF_NORETURN)
                  predict_paths_leading_to (bb, heads, PRED_NORETURN,
                                            NOT_TAKEN);
                if (call_expr_flags (stmt) & ECF_NORETURN)
                  predict_paths_leading_to (bb, heads, PRED_NORETURN,
                                            NOT_TAKEN);

+               decl = get_callee_fndecl (stmt);
+               if (decl
+                   && lookup_attribute ("cold",
+                                        DECL_ATTRIBUTES (decl)))
+                 predict_paths_leading_to (bb, heads, PRED_COLD_FUNCTION,
+                                           NOT_TAKEN);

                break;
              default:
                break;
                break;
              default:
                break;


@@ -1307,26 +1331,44 @@ call_expr:;
   free (heads);
 }
 
   free (heads);
 }
 

+#ifdef ENABLE_CHECKING
+
+/* Callback for pointer_map_traverse, asserts that the pointer map is
+   empty.  */
+
+static bool
+assert_is_empty (const void *key ATTRIBUTE_UNUSED, void **value,
+                void *data ATTRIBUTE_UNUSED)
+{
+  gcc_assert (!*value);
+  return false;
+}
+#endif
+

 /* Predict branch probabilities and estimate profile of the tree CFG.  */
 /* Predict branch probabilities and estimate profile of the tree CFG.  */

-static void
+static unsigned int

 tree_estimate_probability (void)
 {
   basic_block bb;
 tree_estimate_probability (void)
 {
   basic_block bb;

-  struct loops loops_info;

 
 

-  flow_loops_find (&loops_info);
+  loop_optimizer_init (0);

   if (dump_file && (dump_flags & TDF_DETAILS))
   if (dump_file && (dump_flags & TDF_DETAILS))

-    flow_loops_dump (&loops_info, dump_file, NULL, 0);
+    flow_loops_dump (dump_file, NULL, 0);

 
   add_noreturn_fake_exit_edges ();
   connect_infinite_loops_to_exit ();
 
   add_noreturn_fake_exit_edges ();
   connect_infinite_loops_to_exit ();

-  calculate_dominance_info (CDI_DOMINATORS);
+  /* We use loop_niter_by_eval, which requires that the loops have
+     preheaders.  */
+  create_preheaders (CP_SIMPLE_PREHEADERS);

   calculate_dominance_info (CDI_POST_DOMINATORS);
 
   calculate_dominance_info (CDI_POST_DOMINATORS);
 

+  bb_predictions = pointer_map_create ();

   tree_bb_level_predictions ();
 
   tree_bb_level_predictions ();
 

-  mark_irreducible_loops (&loops_info);
-  predict_loops (&loops_info, false);
+  mark_irreducible_loops ();
+  record_loop_exits ();
+  if (number_of_loops () > 1)
+    predict_loops ();

 
   FOR_EACH_BB (bb)
     {
 
   FOR_EACH_BB (bb)
     {


@@ -1337,20 +1379,41 @@ tree_estimate_probability (void)
        {
          /* Predict early returns to be probable, as we've already taken
             care for error returns and other cases are often used for
        {
          /* Predict early returns to be probable, as we've already taken
             care for error returns and other cases are often used for

-            fast paths trought function.  */
-         if (e->dest == EXIT_BLOCK_PTR
-             && TREE_CODE (last_stmt (bb)) == RETURN_EXPR
-             && !single_pred_p (bb))
+            fast paths through function. 
+
+            Since we've already removed the return statements, we are
+            looking for CFG like:
+
+              if (conditional)
+                {
+                  ..
+                  goto return_block
+                }
+              some other blocks
+            return_block:
+              return_stmt.  */
+         if (e->dest != bb->next_bb
+             && e->dest != EXIT_BLOCK_PTR
+             && single_succ_p (e->dest)
+             && single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR
+             && TREE_CODE (last_stmt (e->dest)) == RETURN_EXPR)

            {
              edge e1;
              edge_iterator ei1;
 
            {
              edge e1;
              edge_iterator ei1;
 

-             FOR_EACH_EDGE (e1, ei1, bb->preds)
-               if (!predicted_by_p (e1->src, PRED_NULL_RETURN)
-                   && !predicted_by_p (e1->src, PRED_CONST_RETURN)
-                   && !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN)
-                   && !last_basic_block_p (e1->src))
-                 predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN);
+             if (single_succ_p (bb))
+               {
+                 FOR_EACH_EDGE (e1, ei1, bb->preds)
+                   if (!predicted_by_p (e1->src, PRED_NULL_RETURN)
+                       && !predicted_by_p (e1->src, PRED_CONST_RETURN)
+                       && !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN))
+                     predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN);
+               }
+              else
+               if (!predicted_by_p (e->src, PRED_NULL_RETURN)
+                   && !predicted_by_p (e->src, PRED_CONST_RETURN)
+                   && !predicted_by_p (e->src, PRED_NEGATIVE_RETURN))
+                 predict_edge_def (e, PRED_TREE_EARLY_RETURN, NOT_TAKEN);

            }
 
          /* Look for block we are guarding (ie we dominate it,
            }
 
          /* Look for block we are guarding (ie we dominate it,


@@ -1370,8 +1433,9 @@ tree_estimate_probability (void)
                {
                  tree stmt = bsi_stmt (bi);
                  if ((TREE_CODE (stmt) == CALL_EXPR
                {
                  tree stmt = bsi_stmt (bi);
                  if ((TREE_CODE (stmt) == CALL_EXPR

-                      || (TREE_CODE (stmt) == MODIFY_EXPR
-                          && TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR))
+                      || (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+                          && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1))
+                             == CALL_EXPR))

                      /* Constant and pure calls are hardly used to signalize
                         something exceptional.  */
                      && TREE_SIDE_EFFECTS (stmt))
                      /* Constant and pure calls are hardly used to signalize
                         something exceptional.  */
                      && TREE_SIDE_EFFECTS (stmt))


@@ -1385,107 +1449,26 @@ tree_estimate_probability (void)
       tree_predict_by_opcode (bb);
     }
   FOR_EACH_BB (bb)
       tree_predict_by_opcode (bb);
     }
   FOR_EACH_BB (bb)

-    combine_predictions_for_bb (dump_file, bb);
+    combine_predictions_for_bb (bb);
+
+#ifdef ENABLE_CHECKING
+  pointer_map_traverse (bb_predictions, assert_is_empty, NULL);
+#endif
+  pointer_map_destroy (bb_predictions);
+  bb_predictions = NULL;

 
 

-  if (!flag_loop_optimize)
-    strip_builtin_expect ();
-  estimate_bb_frequencies (&loops_info);
+  strip_builtin_expect ();
+  estimate_bb_frequencies ();

   free_dominance_info (CDI_POST_DOMINATORS);
   remove_fake_exit_edges ();
   free_dominance_info (CDI_POST_DOMINATORS);
   remove_fake_exit_edges ();

-  flow_loops_free (&loops_info);
+  loop_optimizer_finalize ();

   if (dump_file && (dump_flags & TDF_DETAILS))
     dump_tree_cfg (dump_file, dump_flags);
   if (profile_status == PROFILE_ABSENT)
     profile_status = PROFILE_GUESSED;
   if (dump_file && (dump_flags & TDF_DETAILS))
     dump_tree_cfg (dump_file, dump_flags);
   if (profile_status == PROFILE_ABSENT)
     profile_status = PROFILE_GUESSED;

+  return 0;

 }
 \f
 }
 \f

-/* __builtin_expect dropped tokens into the insn stream describing expected
-   values of registers.  Generate branch probabilities based off these
-   values.  */
-
-void
-expected_value_to_br_prob (void)
-{
-  rtx insn, cond, ev = NULL_RTX, ev_reg = NULL_RTX;
-
-  for (insn = get_insns (); insn ; insn = NEXT_INSN (insn))
-    {
-      switch (GET_CODE (insn))
-       {
-       case NOTE:
-         /* Look for expected value notes.  */
-         if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EXPECTED_VALUE)
-           {
-             ev = NOTE_EXPECTED_VALUE (insn);
-             ev_reg = XEXP (ev, 0);
-             delete_insn (insn);
-           }
-         continue;
-
-       case CODE_LABEL:
-         /* Never propagate across labels.  */
-         ev = NULL_RTX;
-         continue;
-
-       case JUMP_INSN:
-         /* Look for simple conditional branches.  If we haven't got an
-            expected value yet, no point going further.  */
-         if (!JUMP_P (insn) || ev == NULL_RTX
-             || ! any_condjump_p (insn))
-           continue;
-         break;
-
-       default:
-         /* Look for insns that clobber the EV register.  */
-         if (ev && reg_set_p (ev_reg, insn))
-           ev = NULL_RTX;
-         continue;
-       }
-
-      /* Collect the branch condition, hopefully relative to EV_REG.  */
-      /* ???  At present we'll miss things like
-               (expected_value (eq r70 0))
-               (set r71 -1)
-               (set r80 (lt r70 r71))
-               (set pc (if_then_else (ne r80 0) ...))
-        as canonicalize_condition will render this to us as
-               (lt r70, r71)
-        Could use cselib to try and reduce this further.  */
-      cond = XEXP (SET_SRC (pc_set (insn)), 0);
-      cond = canonicalize_condition (insn, cond, 0, NULL, ev_reg,
-                                    false, false);
-      if (! cond || XEXP (cond, 0) != ev_reg
-         || GET_CODE (XEXP (cond, 1)) != CONST_INT)
-       continue;
-
-      /* Substitute and simplify.  Given that the expression we're
-        building involves two constants, we should wind up with either
-        true or false.  */
-      cond = gen_rtx_fmt_ee (GET_CODE (cond), VOIDmode,
-                            XEXP (ev, 1), XEXP (cond, 1));
-      cond = simplify_rtx (cond);
-
-      /* Turn the condition into a scaled branch probability.  */
-      gcc_assert (cond == const_true_rtx || cond == const0_rtx);
-      predict_insn_def (insn, PRED_BUILTIN_EXPECT,
-                       cond == const_true_rtx ? TAKEN : NOT_TAKEN);
-    }
-}
-\f
-/* Check whether this is the last basic block of function.  Commonly
-   there is one extra common cleanup block.  */
-static bool
-last_basic_block_p (basic_block bb)
-{
-  if (bb == EXIT_BLOCK_PTR)
-    return false;
-
-  return (bb->next_bb == EXIT_BLOCK_PTR
-         || (bb->next_bb->next_bb == EXIT_BLOCK_PTR
-             && single_succ_p (bb)
-             && single_succ (bb)->next_bb == EXIT_BLOCK_PTR));
-}
-

 /* Sets branch probabilities according to PREDiction and
    FLAGS. HEADS[bb->index] should be index of basic block in that we
    need to alter branch predictions (i.e. the first of our dominators
 /* Sets branch probabilities according to PREDiction and
    FLAGS. HEADS[bb->index] should be index of basic block in that we
    need to alter branch predictions (i.e. the first of our dominators


@@ -1570,12 +1553,12 @@ typedef struct edge_info_def
 #define EDGE_INFO(E)   ((edge_info) (E)->aux)
 
 /* Helper function for estimate_bb_frequencies.
 #define EDGE_INFO(E)   ((edge_info) (E)->aux)
 
 /* Helper function for estimate_bb_frequencies.

-   Propagate the frequencies for LOOP.  */
+   Propagate the frequencies in blocks marked in
+   TOVISIT, starting in HEAD.  */

 
 static void
 
 static void

-propagate_freq (struct loop *loop, bitmap tovisit)
+propagate_freq (basic_block head, bitmap tovisit)

 {
 {

-  basic_block head = loop->header;

   basic_block bb;
   basic_block last;
   unsigned i;
   basic_block bb;
   basic_block last;
   unsigned i;


@@ -1712,7 +1695,7 @@ propagate_freq (struct loop *loop, bitmap tovisit)
 /* Estimate probabilities of loopback edges in loops at same nest level.  */
 
 static void
 /* Estimate probabilities of loopback edges in loops at same nest level.  */
 
 static void

-estimate_loops_at_level (struct loop *first_loop, bitmap tovisit)
+estimate_loops_at_level (struct loop *first_loop)

 {
   struct loop *loop;
 
 {
   struct loop *loop;
 


@@ -1721,25 +1704,44 @@ estimate_loops_at_level (struct loop *first_loop, bitmap tovisit)
       edge e;
       basic_block *bbs;
       unsigned i;
       edge e;
       basic_block *bbs;
       unsigned i;

+      bitmap tovisit = BITMAP_ALLOC (NULL);

 
 

-      estimate_loops_at_level (loop->inner, tovisit);
+      estimate_loops_at_level (loop->inner);

 
 

-      /* Do not do this for dummy function loop.  */
-      if (EDGE_COUNT (loop->latch->succs) > 0)
-       {
-         /* Find current loop back edge and mark it.  */
-         e = loop_latch_edge (loop);
-         EDGE_INFO (e)->back_edge = 1;
-       }
+      /* Find current loop back edge and mark it.  */
+      e = loop_latch_edge (loop);
+      EDGE_INFO (e)->back_edge = 1;

 
       bbs = get_loop_body (loop);
       for (i = 0; i < loop->num_nodes; i++)
        bitmap_set_bit (tovisit, bbs[i]->index);
       free (bbs);
 
       bbs = get_loop_body (loop);
       for (i = 0; i < loop->num_nodes; i++)
        bitmap_set_bit (tovisit, bbs[i]->index);
       free (bbs);

-      propagate_freq (loop, tovisit);
+      propagate_freq (loop->header, tovisit);
+      BITMAP_FREE (tovisit);

     }
 }
 
     }
 }
 

+/* Propagates frequencies through structure of loops.  */
+
+static void
+estimate_loops (void)
+{
+  bitmap tovisit = BITMAP_ALLOC (NULL);
+  basic_block bb;
+
+  /* Start by estimating the frequencies in the loops.  */
+  if (number_of_loops () > 1)
+    estimate_loops_at_level (current_loops->tree_root->inner);
+
+  /* Now propagate the frequencies through all the blocks.  */
+  FOR_ALL_BB (bb)
+    {
+      bitmap_set_bit (tovisit, bb->index);
+    }
+  propagate_freq (ENTRY_BLOCK_PTR, tovisit);
+  BITMAP_FREE (tovisit);
+}
+

 /* Convert counts measured by profile driven feedback to frequencies.
    Return nonzero iff there was any nonzero execution count.  */
 
 /* Convert counts measured by profile driven feedback to frequencies.
    Return nonzero iff there was any nonzero execution count.  */
 


@@ -1755,6 +1757,7 @@ counts_to_freqs (void)
   count_max = MAX (true_count_max, 1);
   FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
     bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max;
   count_max = MAX (true_count_max, 1);
   FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
     bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max;

+

   return true_count_max;
 }
 
   return true_count_max;
 }
 


@@ -1801,8 +1804,8 @@ expensive_function_p (int threshold)
 
 /* Estimate basic blocks frequency by given branch probabilities.  */
 
 
 /* Estimate basic blocks frequency by given branch probabilities.  */
 

-static void
-estimate_bb_frequencies (struct loops *loops)
+void
+estimate_bb_frequencies (void)

 {
   basic_block bb;
   sreal freq_max;
 {
   basic_block bb;
   sreal freq_max;


@@ -1810,7 +1813,6 @@ estimate_bb_frequencies (struct loops *loops)
   if (!flag_branch_probabilities || !counts_to_freqs ())
     {
       static int real_values_initialized = 0;
   if (!flag_branch_probabilities || !counts_to_freqs ())
     {
       static int real_values_initialized = 0;

-      bitmap tovisit;

 
       if (!real_values_initialized)
         {
 
       if (!real_values_initialized)
         {


@@ -1829,7 +1831,6 @@ estimate_bb_frequencies (struct loops *loops)
       single_succ_edge (ENTRY_BLOCK_PTR)->probability = REG_BR_PROB_BASE;
 
       /* Set up block info for each basic block.  */
       single_succ_edge (ENTRY_BLOCK_PTR)->probability = REG_BR_PROB_BASE;
 
       /* Set up block info for each basic block.  */

-      tovisit = BITMAP_ALLOC (NULL);

       alloc_aux_for_blocks (sizeof (struct block_info_def));
       alloc_aux_for_edges (sizeof (struct edge_info_def));
       FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
       alloc_aux_for_blocks (sizeof (struct block_info_def));
       alloc_aux_for_edges (sizeof (struct edge_info_def));
       FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)


@@ -1848,7 +1849,7 @@ estimate_bb_frequencies (struct loops *loops)
 
       /* First compute probabilities locally for each loop from innermost
          to outermost to examine probabilities for back edges.  */
 
       /* First compute probabilities locally for each loop from innermost
          to outermost to examine probabilities for back edges.  */

-      estimate_loops_at_level (loops->tree_root, tovisit);
+      estimate_loops ();

 
       memcpy (&freq_max, &real_zero, sizeof (real_zero));
       FOR_EACH_BB (bb)
 
       memcpy (&freq_max, &real_zero, sizeof (real_zero));
       FOR_EACH_BB (bb)


@@ -1867,7 +1868,6 @@ estimate_bb_frequencies (struct loops *loops)
 
       free_aux_for_blocks ();
       free_aux_for_edges ();
 
       free_aux_for_blocks ();
       free_aux_for_edges ();

-      BITMAP_FREE (tovisit);

     }
   compute_function_frequency ();
   if (flag_reorder_functions)
     }
   compute_function_frequency ();
   if (flag_reorder_functions)


@@ -1881,7 +1881,15 @@ compute_function_frequency (void)
   basic_block bb;
 
   if (!profile_info || !flag_branch_probabilities)
   basic_block bb;
 
   if (!profile_info || !flag_branch_probabilities)

-    return;
+    {
+      if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl))
+         != NULL)
+        cfun->function_frequency = FUNCTION_FREQUENCY_UNLIKELY_EXECUTED;
+      else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl))
+              != NULL)
+        cfun->function_frequency = FUNCTION_FREQUENCY_HOT;
+      return;
+    }

   cfun->function_frequency = FUNCTION_FREQUENCY_UNLIKELY_EXECUTED;
   FOR_EACH_BB (bb)
     {
   cfun->function_frequency = FUNCTION_FREQUENCY_UNLIKELY_EXECUTED;
   FOR_EACH_BB (bb)
     {