Initial checkin of GCC 4.9.0 from trunk (r208799).

Change-Id: I48a3c08bb98542aa215912a75f03c0890e497dba

1 files changed, 3272 insertions, 0 deletions

diff --git a/gcc-4.9/gcc/predict.c b/gcc-4.9/gcc/predict.c
new file mode 100644
index 000000000..249433f91
--- /dev/null
+++ b/gcc-4.9/gcc/predict.c
@@ -0,0 +1,3272 @@
+/* Branch prediction routines for the GNU compiler.
+   Copyright (C) 2000-2014 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 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+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
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+/* References:
+
+   [1] "Branch Prediction for Free"
+       Ball and Larus; PLDI '93.
+   [2] "Static Branch Frequency and Program Profile Analysis"
+       Wu and Larus; MICRO-27.
+   [3] "Corpus-based Static Branch Prediction"
+       Calder, Grunwald, Lindsay, Martin, Mozer, and Zorn; PLDI '95.  */
+
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "tree.h"
+#include "calls.h"
+#include "rtl.h"
+#include "tm_p.h"
+#include "hard-reg-set.h"
+#include "basic-block.h"
+#include "insn-config.h"
+#include "regs.h"
+#include "flags.h"
+#include "function.h"
+#include "except.h"
+#include "diagnostic-core.h"
+#include "recog.h"
+#include "expr.h"
+#include "predict.h"
+#include "coverage.h"
+#include "sreal.h"
+#include "params.h"
+#include "target.h"
+#include "cfgloop.h"
+#include "pointer-set.h"
+#include "tree-ssa-alias.h"
+#include "internal-fn.h"
+#include "gimple-expr.h"
+#include "is-a.h"
+#include "gimple.h"
+#include "gimple-iterator.h"
+#include "gimple-ssa.h"
+#include "cgraph.h"
+#include "tree-cfg.h"
+#include "tree-phinodes.h"
+#include "ssa-iterators.h"
+#include "tree-ssa-loop-niter.h"
+#include "tree-ssa-loop.h"
+#include "tree-pass.h"
+#include "tree-scalar-evolution.h"
+#include "cfgloop.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.  */
+static sreal real_zero, real_one, real_almost_one, real_br_prob_base,
+	     real_inv_br_prob_base, real_one_half, real_bb_freq_max;
+
+static void combine_predictions_for_insn (rtx, basic_block);
+static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int);
+static void predict_paths_leading_to (basic_block, enum br_predictor, enum prediction);
+static void predict_paths_leading_to_edge (edge, enum br_predictor, enum prediction);
+static bool can_predict_insn_p (const_rtx);
+
+/* Information we hold about each branch predictor.
+   Filled using information from predict.def.  */
+
+struct predictor_info
+{
+  const char *const name;	/* Name used in the debugging dumps.  */
+  const int hitrate;		/* Expected hitrate used by
+				   predict_insn_def call.  */
+  const int flags;
+};
+
+/* Use given predictor without Dempster-Shaffer theory if it matches
+   using first_match heuristics.  */
+#define PRED_FLAG_FIRST_MATCH 1
+
+/* Recompute hitrate in percent to our representation.  */
+
+#define HITRATE(VAL) ((int) ((VAL) * REG_BR_PROB_BASE + 50) / 100)
+
+#define DEF_PREDICTOR(ENUM, NAME, HITRATE, FLAGS) {NAME, HITRATE, FLAGS},
+static const struct predictor_info predictor_info[]= {
+#include "predict.def"
+
+  /* Upper bound on predictors.  */
+  {NULL, 0, 0}
+};
+#undef DEF_PREDICTOR
+
+/* Return TRUE if frequency FREQ is considered to be hot.  */
+
+static inline bool
+maybe_hot_frequency_p (struct function *fun, int freq)
+{
+  struct cgraph_node *node = cgraph_get_node (fun->decl);
+  if (!profile_info || !flag_branch_probabilities)
+    {
+      if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED)
+        return false;
+      if (node->frequency == NODE_FREQUENCY_HOT)
+        return true;
+    }
+  if (profile_status_for_fn (fun) == PROFILE_ABSENT)
+    return true;
+  if (node->frequency == NODE_FREQUENCY_EXECUTED_ONCE
+      && freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency * 2 / 3))
+    return false;
+  if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0)
+    return false;
+  if (freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency
+	      / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION)))
+    return false;
+  return true;
+}
+
+static gcov_type min_count = -1;
+
+/* Determine the threshold for hot BB counts.  */
+
+gcov_type
+get_hot_bb_threshold ()
+{
+  gcov_working_set_t *ws;
+  if (min_count == -1)
+    {
+      ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE));
+      gcc_assert (ws);
+      min_count = ws->min_counter;
+    }
+  return min_count;
+}
+
+/* Set the threshold for hot BB counts.  */
+
+void
+set_hot_bb_threshold (gcov_type min)
+{
+  min_count = min;
+}
+
+/* Return TRUE if frequency FREQ is considered to be hot.  */
+
+static inline bool
+maybe_hot_count_p (struct function *fun, gcov_type count)
+{
+  if (fun && profile_status_for_fn (fun) != PROFILE_READ)
+    return true;
+  /* Code executed at most once is not hot.  */
+  if (profile_info->runs >= count)
+    return false;
+  return (count >= get_hot_bb_threshold ());
+}
+
+/* Return true in case BB can be CPU intensive and should be optimized
+   for maximal performance.  */
+
+bool
+maybe_hot_bb_p (struct function *fun, const_basic_block bb)
+{
+  gcc_checking_assert (fun);
+  if (profile_status_for_fn (fun) == PROFILE_READ)
+    return maybe_hot_count_p (fun, bb->count);
+  return maybe_hot_frequency_p (fun, bb->frequency);
+}
+
+/* Return true if the call can be hot.  */
+
+bool
+cgraph_maybe_hot_edge_p (struct cgraph_edge *edge)
+{
+  if (profile_info && flag_branch_probabilities
+      && !maybe_hot_count_p (NULL,
+                             edge->count))
+    return false;
+  if (edge->caller->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED
+      || (edge->callee
+	  && edge->callee->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED))
+    return false;
+  if (edge->caller->frequency > NODE_FREQUENCY_UNLIKELY_EXECUTED
+      && (edge->callee
+	  && edge->callee->frequency <= NODE_FREQUENCY_EXECUTED_ONCE))
+    return false;
+  if (optimize_size)
+    return false;
+  if (edge->caller->frequency == NODE_FREQUENCY_HOT)
+    return true;
+  if (edge->caller->frequency == NODE_FREQUENCY_EXECUTED_ONCE
+      && edge->frequency < CGRAPH_FREQ_BASE * 3 / 2)
+    return false;
+  if (flag_guess_branch_prob)
+    {
+      if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0
+	  || edge->frequency <= (CGRAPH_FREQ_BASE
+				 / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION)))
+        return false;
+    }
+  return true;
+}
+
+/* Return true in case BB can be CPU intensive and should be optimized
+   for maximal performance.  */
+
+bool
+maybe_hot_edge_p (edge e)
+{
+  if (profile_status_for_fn (cfun) == PROFILE_READ)
+    return maybe_hot_count_p (cfun, e->count);
+  return maybe_hot_frequency_p (cfun, EDGE_FREQUENCY (e));
+}
+
+
+
+/* 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_fn (cfun) == PROFILE_READ)
+    {
+      int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION);
+      if (count * unlikely_count_fraction >= profile_info->runs)
+	return false;
+      if (!frequency)
+	return true;
+      if (!ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency)
+	return false;
+      if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count)
+	{
+          gcov_type computed_count;
+          /* Check for possibility of overflow, in which case entry bb count
+             is large enough to do the division first without losing much
+             precision.  */
+	  if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count < REG_BR_PROB_BASE *
+	      REG_BR_PROB_BASE)
+            {
+              gcov_type scaled_count
+		  = frequency * ENTRY_BLOCK_PTR_FOR_FN (cfun)->count *
+	     unlikely_count_fraction;
+	      computed_count = RDIV (scaled_count,
+				     ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency);
+            }
+          else
+            {
+	      computed_count = RDIV (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count,
+				     ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency);
+              computed_count *= frequency * unlikely_count_fraction;
+            }
+          if (computed_count >= profile_info->runs)
+            return false;
+	}
+      return true;
+    }
+  if ((!profile_info || !flag_branch_probabilities)
+      && (cgraph_get_node (fun->decl)->frequency
+	  == NODE_FREQUENCY_UNLIKELY_EXECUTED))
+    return true;
+  return false;
+}
+
+
+/* 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)
+{
+  return probably_never_executed (fun, e->count, EDGE_FREQUENCY (e));
+}
+
+/* Return true if NODE should be optimized for size.  */
+
+bool
+cgraph_optimize_for_size_p (struct cgraph_node *node)
+{
+  if (optimize_size)
+    return true;
+  if (node && (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED))
+    return true;
+  else
+    return false;
+}
+
+/* Return true when current function should always be optimized for size.  */
+
+bool
+optimize_function_for_size_p (struct function *fun)
+{
+  if (optimize_size)
+    return true;
+  if (!fun || !fun->decl)
+    return false;
+  return cgraph_optimize_for_size_p (cgraph_get_node (fun->decl));
+}
+
+/* Return true when current function should always be optimized for speed.  */
+
+bool
+optimize_function_for_speed_p (struct function *fun)
+{
+  return !optimize_function_for_size_p (fun);
+}
+
+/* Return TRUE when BB should be optimized for size.  */
+
+bool
+optimize_bb_for_size_p (const_basic_block bb)
+{
+  return optimize_function_for_size_p (cfun) || !maybe_hot_bb_p (cfun, bb);
+}
+
+/* Return TRUE when BB should be optimized for speed.  */
+
+bool
+optimize_bb_for_speed_p (const_basic_block bb)
+{
+  return !optimize_bb_for_size_p (bb);
+}
+
+/* Return TRUE when BB should be optimized for size.  */
+
+bool
+optimize_edge_for_size_p (edge e)
+{
+  return optimize_function_for_size_p (cfun) || !maybe_hot_edge_p (e);
+}
+
+/* Return TRUE when BB should be optimized for speed.  */
+
+bool
+optimize_edge_for_speed_p (edge e)
+{
+  return !optimize_edge_for_size_p (e);
+}
+
+/* Return TRUE when BB should be optimized for size.  */
+
+bool
+optimize_insn_for_size_p (void)
+{
+  return optimize_function_for_size_p (cfun) || !crtl->maybe_hot_insn_p;
+}
+
+/* Return TRUE when BB should be optimized for speed.  */
+
+bool
+optimize_insn_for_speed_p (void)
+{
+  return !optimize_insn_for_size_p ();
+}
+
+/* Return TRUE when LOOP should be optimized for size.  */
+
+bool
+optimize_loop_for_size_p (struct loop *loop)
+{
+  return optimize_bb_for_size_p (loop->header);
+}
+
+/* Return TRUE when LOOP should be optimized for speed.  */
+
+bool
+optimize_loop_for_speed_p (struct loop *loop)
+{
+  return optimize_bb_for_speed_p (loop->header);
+}
+
+/* Return TRUE when LOOP nest should be optimized for speed.  */
+
+bool
+optimize_loop_nest_for_speed_p (struct loop *loop)
+{
+  struct loop *l = loop;
+  if (optimize_loop_for_speed_p (loop))
+    return true;
+  l = loop->inner;
+  while (l && l != loop)
+    {
+      if (optimize_loop_for_speed_p (l))
+        return true;
+      if (l->inner)
+        l = l->inner;
+      else if (l->next)
+        l = l->next;
+      else
+        {
+	  while (l != loop && !l->next)
+	    l = loop_outer (l);
+	  if (l != loop)
+	    l = l->next;
+	}
+    }
+  return false;
+}
+
+/* Return TRUE when LOOP nest should be optimized for size.  */
+
+bool
+optimize_loop_nest_for_size_p (struct loop *loop)
+{
+  return !optimize_loop_nest_for_speed_p (loop);
+}
+
+/* Return true when edge E is likely to be well predictable by branch
+   predictor.  */
+
+bool
+predictable_edge_p (edge e)
+{
+  if (profile_status_for_fn (cfun) == PROFILE_ABSENT)
+    return false;
+  if ((e->probability
+       <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100)
+      || (REG_BR_PROB_BASE - e->probability
+          <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100))
+    return true;
+  return false;
+}
+
+
+/* Set RTL expansion for BB profile.  */
+
+void
+rtl_profile_for_bb (basic_block bb)
+{
+  crtl->maybe_hot_insn_p = maybe_hot_bb_p (cfun, bb);
+}
+
+/* Set RTL expansion for edge profile.  */
+
+void
+rtl_profile_for_edge (edge e)
+{
+  crtl->maybe_hot_insn_p = maybe_hot_edge_p (e);
+}
+
+/* Set RTL expansion to default mode (i.e. when profile info is not known).  */
+void
+default_rtl_profile (void)
+{
+  crtl->maybe_hot_insn_p = true;
+}
+
+/* Return true if the one of outgoing edges is already predicted by
+   PREDICTOR.  */
+
+bool
+rtl_predicted_by_p (const_basic_block bb, enum br_predictor predictor)
+{
+  rtx note;
+  if (!INSN_P (BB_END (bb)))
+    return false;
+  for (note = REG_NOTES (BB_END (bb)); note; note = XEXP (note, 1))
+    if (REG_NOTE_KIND (note) == REG_BR_PRED
+	&& INTVAL (XEXP (XEXP (note, 0), 0)) == (int)predictor)
+      return true;
+  return false;
+}
+
+/* This map contains for a basic block the list of predictions for the
+   outgoing edges.  */
+
+static struct pointer_map_t *bb_predictions;
+
+/*  Structure representing predictions in tree level. */
+
+struct edge_prediction {
+    struct edge_prediction *ep_next;
+    edge ep_edge;
+    enum br_predictor ep_predictor;
+    int ep_probability;
+};
+
+/* Return true if the one of outgoing edges is already predicted by
+   PREDICTOR.  */
+
+bool
+gimple_predicted_by_p (const_basic_block bb, enum br_predictor predictor)
+{
+  struct edge_prediction *i;
+  void **preds = pointer_map_contains (bb_predictions, bb);
+
+  if (!preds)
+    return false;
+
+  for (i = (struct edge_prediction *) *preds; i; i = i->ep_next)
+    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_for_fn (cfun) == PROFILE_READ
+	  || (profile_status_for_fn (cfun) == 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 (XINT (note, 0));
+}
+
+static void
+predict_insn (rtx insn, enum br_predictor predictor, int probability)
+{
+  gcc_assert (any_condjump_p (insn));
+  if (!flag_guess_branch_prob)
+    return;
+
+  add_reg_note (insn, REG_BR_PRED,
+		gen_rtx_CONCAT (VOIDmode,
+				GEN_INT ((int) predictor),
+				GEN_INT ((int) probability)));
+}
+
+/* Predict insn by given predictor.  */
+
+void
+predict_insn_def (rtx insn, enum br_predictor predictor,
+		  enum prediction taken)
+{
+   int probability = predictor_info[(int) predictor].hitrate;
+
+   if (taken != TAKEN)
+     probability = REG_BR_PROB_BASE - probability;
+
+   predict_insn (insn, predictor, probability);
+}
+
+/* Predict edge E with given probability if possible.  */
+
+void
+rtl_predict_edge (edge e, enum br_predictor predictor, int probability)
+{
+  rtx last_insn;
+  last_insn = BB_END (e->src);
+
+  /* We can store the branch prediction information only about
+     conditional jumps.  */
+  if (!any_condjump_p (last_insn))
+    return;
+
+  /* We always store probability of branching.  */
+  if (e->flags & EDGE_FALLTHRU)
+    probability = REG_BR_PROB_BASE - probability;
+
+  predict_insn (last_insn, predictor, probability);
+}
+
+/* Predict edge E with the given PROBABILITY.  */
+void
+gimple_predict_edge (edge e, enum br_predictor predictor, int probability)
+{
+  gcc_assert (profile_status_for_fn (cfun) != PROFILE_GUESSED);
+  if ((e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) && EDGE_COUNT (e->src->succs) >
+       1)
+      && flag_guess_branch_prob && optimize)
+    {
+      struct edge_prediction *i = XNEW (struct edge_prediction);
+      void **preds = pointer_map_insert (bb_predictions, e->src);
+
+      i->ep_next = (struct edge_prediction *) *preds;
+      *preds = i;
+      i->ep_probability = probability;
+      i->ep_predictor = predictor;
+      i->ep_edge = e;
+    }
+}
+
+/* Remove all predictions on given basic block that are attached
+   to edge E.  */
+void
+remove_predictions_associated_with_edge (edge e)
+{
+  void **preds;
+
+  if (!bb_predictions)
+    return;
+
+  preds = pointer_map_contains (bb_predictions, e->src);
+
+  if (preds)
+    {
+      struct edge_prediction **prediction = (struct edge_prediction **) preds;
+      struct edge_prediction *next;
+
+      while (*prediction)
+	{
+	  if ((*prediction)->ep_edge == e)
+	    {
+	      next = (*prediction)->ep_next;
+	      free (*prediction);
+	      *prediction = 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 = (struct edge_prediction *) *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
+can_predict_insn_p (const_rtx insn)
+{
+  return (JUMP_P (insn)
+	  && any_condjump_p (insn)
+	  && EDGE_COUNT (BLOCK_FOR_INSN (insn)->succs) >= 2);
+}
+
+/* Predict edge E by given predictor if possible.  */
+
+void
+predict_edge_def (edge e, enum br_predictor predictor,
+		  enum prediction taken)
+{
+   int probability = predictor_info[(int) predictor].hitrate;
+
+   if (taken != TAKEN)
+     probability = REG_BR_PROB_BASE - probability;
+
+   predict_edge (e, predictor, probability);
+}
+
+/* Invert all branch predictions or probability notes in the INSN.  This needs
+   to be done each time we invert the condition used by the jump.  */
+
+void
+invert_br_probabilities (rtx insn)
+{
+  rtx note;
+
+  for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
+    if (REG_NOTE_KIND (note) == REG_BR_PROB)
+      XINT (note, 0) = REG_BR_PROB_BASE - XINT (note, 0);
+    else if (REG_NOTE_KIND (note) == REG_BR_PRED)
+      XEXP (XEXP (note, 0), 1)
+	= GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (XEXP (note, 0), 1)));
+}
+
+/* Dump information about the branch prediction to the output file.  */
+
+static void
+dump_prediction (FILE *file, enum br_predictor predictor, int probability,
+		 basic_block bb, int used)
+{
+  edge e;
+  edge_iterator ei;
+
+  if (!file)
+    return;
+
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    if (! (e->flags & EDGE_FALLTHRU))
+      break;
+
+  fprintf (file, "  %s heuristics%s: %.1f%%",
+	   predictor_info[predictor].name,
+	   used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE);
+
+  if (bb->count)
+    {
+      fprintf (file, "  exec ");
+      fprintf (file, HOST_WIDEST_INT_PRINT_DEC, bb->count);
+      if (e)
+	{
+	  fprintf (file, " hit ");
+	  fprintf (file, HOST_WIDEST_INT_PRINT_DEC, e->count);
+	  fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count);
+	}
+    }
+
+  fprintf (file, "\n");
+}
+
+/* We can not predict the probabilities of outgoing edges of bb.  Set them
+   evenly and hope for the best.  */
+static void
+set_even_probabilities (basic_block bb)
+{
+  int nedges = 0;
+  edge e;
+  edge_iterator ei;
+
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    if (!(e->flags & (EDGE_EH | EDGE_FAKE)))
+      nedges ++;
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    if (!(e->flags & (EDGE_EH | EDGE_FAKE)))
+      e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges;
+    else
+      e->probability = 0;
+}
+
+/* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB
+   note if not already present.  Remove now useless REG_BR_PRED notes.  */
+
+static void
+combine_predictions_for_insn (rtx insn, basic_block bb)
+{
+  rtx prob_note;
+  rtx *pnote;
+  rtx note;
+  int best_probability = PROB_EVEN;
+  enum br_predictor best_predictor = END_PREDICTORS;
+  int combined_probability = REG_BR_PROB_BASE / 2;
+  int d;
+  bool first_match = false;
+  bool found = false;
+
+  if (!can_predict_insn_p (insn))
+    {
+      set_even_probabilities (bb);
+      return;
+    }
+
+  prob_note = find_reg_note (insn, REG_BR_PROB, 0);
+  pnote = &REG_NOTES (insn);
+  if (dump_file)
+    fprintf (dump_file, "Predictions for insn %i bb %i\n", INSN_UID (insn),
+	     bb->index);
+
+  /* We implement "first match" heuristics and use probability guessed
+     by predictor with smallest index.  */
+  for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
+    if (REG_NOTE_KIND (note) == REG_BR_PRED)
+      {
+	enum br_predictor predictor = ((enum br_predictor)
+				       INTVAL (XEXP (XEXP (note, 0), 0)));
+	int probability = INTVAL (XEXP (XEXP (note, 0), 1));
+
+	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));
+
+	/* 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,
+     use no_prediction heuristic, in case we did match, use either
+     first match or Dempster-Shaffer theory depending on the flags.  */
+
+  if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH)
+    first_match = true;
+
+  if (!found)
+    dump_prediction (dump_file, PRED_NO_PREDICTION,
+		     combined_probability, bb, true);
+  else
+    {
+      dump_prediction (dump_file, PRED_DS_THEORY, combined_probability,
+		       bb, !first_match);
+      dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability,
+		       bb, first_match);
+    }
+
+  if (first_match)
+    combined_probability = best_probability;
+  dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true);
+
+  while (*pnote)
+    {
+      if (REG_NOTE_KIND (*pnote) == REG_BR_PRED)
+	{
+	  enum br_predictor predictor = ((enum br_predictor)
+					 INTVAL (XEXP (XEXP (*pnote, 0), 0)));
+	  int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1));
+
+	  dump_prediction (dump_file, predictor, probability, bb,
+			   !first_match || best_predictor == predictor);
+	  *pnote = XEXP (*pnote, 1);
+	}
+      else
+	pnote = &XEXP (*pnote, 1);
+    }
+
+  if (!prob_note)
+    {
+      add_int_reg_note (insn, REG_BR_PROB, combined_probability);
+
+      /* Save the prediction into CFG in case we are seeing non-degenerated
+	 conditional jump.  */
+      if (!single_succ_p (bb))
+	{
+	  BRANCH_EDGE (bb)->probability = combined_probability;
+	  FALLTHRU_EDGE (bb)->probability
+	    = REG_BR_PROB_BASE - combined_probability;
+	}
+    }
+  else if (!single_succ_p (bb))
+    {
+      int prob = XINT (prob_note, 0);
+
+      BRANCH_EDGE (bb)->probability = prob;
+      FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob;
+    }
+  else
+    single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
+}
+
+/* Combine predictions into single probability and store them into CFG.
+   Remove now useless prediction entries.  */
+
+static void
+combine_predictions_for_bb (basic_block bb)
+{
+  int best_probability = PROB_EVEN;
+  enum br_predictor best_predictor = END_PREDICTORS;
+  int combined_probability = REG_BR_PROB_BASE / 2;
+  int d;
+  bool first_match = false;
+  bool found = false;
+  struct edge_prediction *pred;
+  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)))
+      {
+	nedges ++;
+	if (first && !second)
+	  second = e;
+	if (!first)
+	  first = e;
+      }
+
+  /* When there is no successor or only one choice, prediction is easy.
+
+     We are lazy for now and predict only basic blocks with two outgoing
+     edges.  It is possible to predict generic case too, but we have to
+     ignore first match heuristics and do more involved combining.  Implement
+     this later.  */
+  if (nedges != 2)
+    {
+      if (!bb->count)
+	set_even_probabilities (bb);
+      clear_bb_predictions (bb);
+      if (dump_file)
+	fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n",
+		 nedges, bb->index);
+      return;
+    }
+
+  if (dump_file)
+    fprintf (dump_file, "Predictions for bb %i\n", bb->index);
+
+  preds = pointer_map_contains (bb_predictions, bb);
+  if (preds)
+    {
+      /* We implement "first match" heuristics and use probability guessed
+	 by predictor with smallest index.  */
+      for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next)
+	{
+	  enum br_predictor predictor = pred->ep_predictor;
+	  int probability = pred->ep_probability;
+
+	  if (pred->ep_edge != first)
+	    probability = REG_BR_PROB_BASE - probability;
+
+	  found = true;
+	  /* First match heuristics would be widly confused if we predicted
+	     both directions.  */
+	  if (best_predictor > predictor)
+	    {
+              struct edge_prediction *pred2;
+	      int prob = probability;
+
+	      for (pred2 = (struct edge_prediction *) *preds;
+		   pred2; pred2 = pred2->ep_next)
+	       if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor)
+	         {
+	           int probability2 = pred->ep_probability;
+
+		   if (pred2->ep_edge != first)
+		     probability2 = REG_BR_PROB_BASE - probability2;
+
+		   if ((probability < REG_BR_PROB_BASE / 2) !=
+		       (probability2 < REG_BR_PROB_BASE / 2))
+		     break;
+
+		   /* If the same predictor later gave better result, go for it! */
+		   if ((probability >= REG_BR_PROB_BASE / 2 && (probability2 > probability))
+		       || (probability <= REG_BR_PROB_BASE / 2 && (probability2 < probability)))
+		     prob = probability2;
+		 }
+	      if (!pred2)
+	        best_probability = prob, best_predictor = predictor;
+	    }
+
+	  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);
+	}
+    }
+
+  /* Decide which heuristic to use.  In case we didn't match anything,
+     use no_prediction heuristic, in case we did match, use either
+     first match or Dempster-Shaffer theory depending on the flags.  */
+
+  if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH)
+    first_match = true;
+
+  if (!found)
+    dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true);
+  else
+    {
+      dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb,
+		       !first_match);
+      dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb,
+		       first_match);
+    }
+
+  if (first_match)
+    combined_probability = best_probability;
+  dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true);
+
+  if (preds)
+    {
+      for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next)
+	{
+	  enum br_predictor 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 (dump_file, predictor, probability, bb,
+			   !first_match || best_predictor == predictor);
+	}
+    }
+  clear_bb_predictions (bb);
+
+  if (!bb->count)
+    {
+      first->probability = combined_probability;
+      second->probability = REG_BR_PROB_BASE - combined_probability;
+    }
+}
+
+/* Check if T1 and T2 satisfy the IV_COMPARE condition.
+   Return the SSA_NAME if the condition satisfies, NULL otherwise.
+
+   T1 and T2 should be one of the following cases:
+     1. T1 is SSA_NAME, T2 is NULL
+     2. T1 is SSA_NAME, T2 is INTEGER_CST between [-4, 4]
+     3. T2 is SSA_NAME, T1 is INTEGER_CST between [-4, 4]  */
+
+static tree
+strips_small_constant (tree t1, tree t2)
+{
+  tree ret = NULL;
+  int value = 0;
+
+  if (!t1)
+    return NULL;
+  else if (TREE_CODE (t1) == SSA_NAME)
+    ret = t1;
+  else if (tree_fits_shwi_p (t1))
+    value = tree_to_shwi (t1);
+  else
+    return NULL;
+
+  if (!t2)
+    return ret;
+  else if (tree_fits_shwi_p (t2))
+    value = tree_to_shwi (t2);
+  else if (TREE_CODE (t2) == SSA_NAME)
+    {
+      if (ret)
+        return NULL;
+      else
+        ret = t2;
+    }
+
+  if (value <= 4 && value >= -4)
+    return ret;
+  else
+    return NULL;
+}
+
+/* Return the SSA_NAME in T or T's operands.
+   Return NULL if SSA_NAME cannot be found.  */
+
+static tree
+get_base_value (tree t)
+{
+  if (TREE_CODE (t) == SSA_NAME)
+    return t;
+
+  if (!BINARY_CLASS_P (t))
+    return NULL;
+
+  switch (TREE_OPERAND_LENGTH (t))
+    {
+    case 1:
+      return strips_small_constant (TREE_OPERAND (t, 0), NULL);
+    case 2:
+      return strips_small_constant (TREE_OPERAND (t, 0),
+				    TREE_OPERAND (t, 1));
+    default:
+      return NULL;
+    }
+}
+
+/* Check the compare STMT in LOOP. If it compares an induction
+   variable to a loop invariant, return true, and save
+   LOOP_INVARIANT, COMPARE_CODE and LOOP_STEP.
+   Otherwise return false and set LOOP_INVAIANT to NULL.  */
+
+static bool
+is_comparison_with_loop_invariant_p (gimple stmt, struct loop *loop,
+				     tree *loop_invariant,
+				     enum tree_code *compare_code,
+				     tree *loop_step,
+				     tree *loop_iv_base)
+{
+  tree op0, op1, bound, base;
+  affine_iv iv0, iv1;
+  enum tree_code code;
+  tree step;
+
+  code = gimple_cond_code (stmt);
+  *loop_invariant = NULL;
+
+  switch (code)
+    {
+    case GT_EXPR:
+    case GE_EXPR:
+    case NE_EXPR:
+    case LT_EXPR:
+    case LE_EXPR:
+    case EQ_EXPR:
+      break;
+
+    default:
+      return false;
+    }
+
+  op0 = gimple_cond_lhs (stmt);
+  op1 = gimple_cond_rhs (stmt);
+
+  if ((TREE_CODE (op0) != SSA_NAME && TREE_CODE (op0) != INTEGER_CST) 
+       || (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op1) != INTEGER_CST))
+    return false;
+  if (!simple_iv (loop, loop_containing_stmt (stmt), op0, &iv0, true))
+    return false;
+  if (!simple_iv (loop, loop_containing_stmt (stmt), op1, &iv1, true))
+    return false;
+  if (TREE_CODE (iv0.step) != INTEGER_CST
+      || TREE_CODE (iv1.step) != INTEGER_CST)
+    return false;
+  if ((integer_zerop (iv0.step) && integer_zerop (iv1.step))
+      || (!integer_zerop (iv0.step) && !integer_zerop (iv1.step)))
+    return false;
+
+  if (integer_zerop (iv0.step))
+    {
+      if (code != NE_EXPR && code != EQ_EXPR)
+	code = invert_tree_comparison (code, false);
+      bound = iv0.base;
+      base = iv1.base;
+      if (tree_fits_shwi_p (iv1.step))
+	step = iv1.step;
+      else
+	return false;
+    }
+  else
+    {
+      bound = iv1.base;
+      base = iv0.base;
+      if (tree_fits_shwi_p (iv0.step))
+	step = iv0.step;
+      else
+	return false;
+    }
+
+  if (TREE_CODE (bound) != INTEGER_CST)
+    bound = get_base_value (bound);
+  if (!bound)
+    return false;
+  if (TREE_CODE (base) != INTEGER_CST)
+    base = get_base_value (base);
+  if (!base)
+    return false;
+
+  *loop_invariant = bound;
+  *compare_code = code;
+  *loop_step = step;
+  *loop_iv_base = base;
+  return true;
+}
+
+/* Compare two SSA_NAMEs: returns TRUE if T1 and T2 are value coherent.  */
+
+static bool
+expr_coherent_p (tree t1, tree t2)
+{
+  gimple stmt;
+  tree ssa_name_1 = NULL;
+  tree ssa_name_2 = NULL;
+
+  gcc_assert (TREE_CODE (t1) == SSA_NAME || TREE_CODE (t1) == INTEGER_CST);
+  gcc_assert (TREE_CODE (t2) == SSA_NAME || TREE_CODE (t2) == INTEGER_CST);
+
+  if (t1 == t2)
+    return true;
+
+  if (TREE_CODE (t1) == INTEGER_CST && TREE_CODE (t2) == INTEGER_CST)
+    return true;
+  if (TREE_CODE (t1) == INTEGER_CST || TREE_CODE (t2) == INTEGER_CST)
+    return false;
+
+  /* Check to see if t1 is expressed/defined with t2.  */
+  stmt = SSA_NAME_DEF_STMT (t1);
+  gcc_assert (stmt != NULL);
+  if (is_gimple_assign (stmt))
+    {
+      ssa_name_1 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE);
+      if (ssa_name_1 && ssa_name_1 == t2)
+	return true;
+    }
+
+  /* Check to see if t2 is expressed/defined with t1.  */
+  stmt = SSA_NAME_DEF_STMT (t2);
+  gcc_assert (stmt != NULL);
+  if (is_gimple_assign (stmt))
+    {
+      ssa_name_2 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE);
+      if (ssa_name_2 && ssa_name_2 == t1)
+	return true;
+    }
+
+  /* Compare if t1 and t2's def_stmts are identical.  */
+  if (ssa_name_2 != NULL && ssa_name_1 == ssa_name_2)
+    return true;
+  else
+    return false;
+}
+
+/* Predict branch probability of BB when BB contains a branch that compares
+   an induction variable in LOOP with LOOP_IV_BASE_VAR to LOOP_BOUND_VAR. The
+   loop exit is compared using LOOP_BOUND_CODE, with step of LOOP_BOUND_STEP.
+
+   E.g.
+     for (int i = 0; i < bound; i++) {
+       if (i < bound - 2)
+	 computation_1();
+       else
+	 computation_2();
+     }
+
+  In this loop, we will predict the branch inside the loop to be taken.  */
+
+static void
+predict_iv_comparison (struct loop *loop, basic_block bb,
+		       tree loop_bound_var,
+		       tree loop_iv_base_var,
+		       enum tree_code loop_bound_code,
+		       int loop_bound_step)
+{
+  gimple stmt;
+  tree compare_var, compare_base;
+  enum tree_code compare_code;
+  tree compare_step_var;
+  edge then_edge;
+  edge_iterator ei;
+
+  if (predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED)
+      || predicted_by_p (bb, PRED_LOOP_ITERATIONS)
+      || predicted_by_p (bb, PRED_LOOP_EXIT))
+    return;
+
+  stmt = last_stmt (bb);
+  if (!stmt || gimple_code (stmt) != GIMPLE_COND)
+    return;
+  if (!is_comparison_with_loop_invariant_p (stmt, loop, &compare_var,
+					    &compare_code,
+					    &compare_step_var,
+					    &compare_base))
+    return;
+
+  /* Find the taken edge.  */
+  FOR_EACH_EDGE (then_edge, ei, bb->succs)
+    if (then_edge->flags & EDGE_TRUE_VALUE)
+      break;
+
+  /* When comparing an IV to a loop invariant, NE is more likely to be
+     taken while EQ is more likely to be not-taken.  */
+  if (compare_code == NE_EXPR)
+    {
+      predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN);
+      return;
+    }
+  else if (compare_code == EQ_EXPR)
+    {
+      predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN);
+      return;
+    }
+
+  if (!expr_coherent_p (loop_iv_base_var, compare_base))
+    return;
+
+  /* If loop bound, base and compare bound are all constants, we can
+     calculate the probability directly.  */
+  if (tree_fits_shwi_p (loop_bound_var)
+      && tree_fits_shwi_p (compare_var)
+      && tree_fits_shwi_p (compare_base))
+    {
+      int probability;
+      bool of, overflow = false;
+      double_int mod, compare_count, tem, loop_count;
+
+      double_int loop_bound = tree_to_double_int (loop_bound_var);
+      double_int compare_bound = tree_to_double_int (compare_var);
+      double_int base = tree_to_double_int (compare_base);
+      double_int compare_step = tree_to_double_int (compare_step_var);
+
+      /* (loop_bound - base) / compare_step */
+      tem = loop_bound.sub_with_overflow (base, &of);
+      overflow |= of;
+      loop_count = tem.divmod_with_overflow (compare_step,
+					      0, TRUNC_DIV_EXPR,
+					      &mod, &of);
+      overflow |= of;
+
+      if ((!compare_step.is_negative ())
+          ^ (compare_code == LT_EXPR || compare_code == LE_EXPR))
+	{
+	  /* (loop_bound - compare_bound) / compare_step */
+	  tem = loop_bound.sub_with_overflow (compare_bound, &of);
+	  overflow |= of;
+	  compare_count = tem.divmod_with_overflow (compare_step,
+						     0, TRUNC_DIV_EXPR,
+						     &mod, &of);
+	  overflow |= of;
+	}
+      else
+        {
+	  /* (compare_bound - base) / compare_step */
+	  tem = compare_bound.sub_with_overflow (base, &of);
+	  overflow |= of;
+          compare_count = tem.divmod_with_overflow (compare_step,
+						     0, TRUNC_DIV_EXPR,
+						     &mod, &of);
+	  overflow |= of;
+	}
+      if (compare_code == LE_EXPR || compare_code == GE_EXPR)
+	++compare_count;
+      if (loop_bound_code == LE_EXPR || loop_bound_code == GE_EXPR)
+	++loop_count;
+      if (compare_count.is_negative ())
+        compare_count = double_int_zero;
+      if (loop_count.is_negative ())
+        loop_count = double_int_zero;
+      if (loop_count.is_zero ())
+	probability = 0;
+      else if (compare_count.scmp (loop_count) == 1)
+	probability = REG_BR_PROB_BASE;
+      else
+        {
+	  /* If loop_count is too big, such that REG_BR_PROB_BASE * loop_count
+	     could overflow, shift both loop_count and compare_count right
+	     a bit so that it doesn't overflow.  Note both counts are known not
+	     to be negative at this point.  */
+	  int clz_bits = clz_hwi (loop_count.high);
+	  gcc_assert (REG_BR_PROB_BASE < 32768);
+	  if (clz_bits < 16)
+	    {
+	      loop_count.arshift (16 - clz_bits, HOST_BITS_PER_DOUBLE_INT);
+	      compare_count.arshift (16 - clz_bits, HOST_BITS_PER_DOUBLE_INT);
+	    }
+	  tem = compare_count.mul_with_sign (double_int::from_shwi
+					    (REG_BR_PROB_BASE), true, &of);
+	  gcc_assert (!of);
+	  tem = tem.divmod (loop_count, true, TRUNC_DIV_EXPR, &mod);
+	  probability = tem.to_uhwi ();
+	}
+
+      if (!overflow)
+        predict_edge (then_edge, PRED_LOOP_IV_COMPARE, probability);
+
+      return;
+    }
+
+  if (expr_coherent_p (loop_bound_var, compare_var))
+    {
+      if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR)
+	  && (compare_code == LT_EXPR || compare_code == LE_EXPR))
+	predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN);
+      else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR)
+	       && (compare_code == GT_EXPR || compare_code == GE_EXPR))
+	predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN);
+      else if (loop_bound_code == NE_EXPR)
+	{
+	  /* If the loop backedge condition is "(i != bound)", we do
+	     the comparison based on the step of IV:
+	     * step < 0 : backedge condition is like (i > bound)
+	     * step > 0 : backedge condition is like (i < bound)  */
+	  gcc_assert (loop_bound_step != 0);
+	  if (loop_bound_step > 0
+	      && (compare_code == LT_EXPR
+		  || compare_code == LE_EXPR))
+	    predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN);
+	  else if (loop_bound_step < 0
+		   && (compare_code == GT_EXPR
+		       || compare_code == GE_EXPR))
+	    predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN);
+	  else
+	    predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN);
+	}
+      else
+	/* The branch is predicted not-taken if loop_bound_code is
+	   opposite with compare_code.  */
+	predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN);
+    }
+  else if (expr_coherent_p (loop_iv_base_var, compare_var))
+    {
+      /* For cases like:
+	   for (i = s; i < h; i++)
+	     if (i > s + 2) ....
+	 The branch should be predicted taken.  */
+      if (loop_bound_step > 0
+	  && (compare_code == GT_EXPR || compare_code == GE_EXPR))
+	predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN);
+      else if (loop_bound_step < 0
+	       && (compare_code == LT_EXPR || compare_code == LE_EXPR))
+	predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN);
+      else
+	predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN);
+    }
+}
+
+/* Predict for extra loop exits that will lead to EXIT_EDGE. The extra loop
+   exits are resulted from short-circuit conditions that will generate an
+   if_tmp. E.g.:
+
+   if (foo() || global > 10)
+     break;
+
+   This will be translated into:
+
+   BB3:
+     loop header...
+   BB4:
+     if foo() goto BB6 else goto BB5
+   BB5:
+     if global > 10 goto BB6 else goto BB7
+   BB6:
+     goto BB7
+   BB7:
+     iftmp = (PHI 0(BB5), 1(BB6))
+     if iftmp == 1 goto BB8 else goto BB3
+   BB8:
+     outside of the loop...
+
+   The edge BB7->BB8 is loop exit because BB8 is outside of the loop.
+   From the dataflow, we can infer that BB4->BB6 and BB5->BB6 are also loop
+   exits. This function takes BB7->BB8 as input, and finds out the extra loop
+   exits to predict them using PRED_LOOP_EXIT.  */
+
+static void
+predict_extra_loop_exits (edge exit_edge)
+{
+  unsigned i;
+  bool check_value_one;
+  gimple phi_stmt;
+  tree cmp_rhs, cmp_lhs;
+  gimple cmp_stmt = last_stmt (exit_edge->src);
+
+  if (!cmp_stmt || gimple_code (cmp_stmt) != GIMPLE_COND)
+    return;
+  cmp_rhs = gimple_cond_rhs (cmp_stmt);
+  cmp_lhs = gimple_cond_lhs (cmp_stmt);
+  if (!TREE_CONSTANT (cmp_rhs)
+      || !(integer_zerop (cmp_rhs) || integer_onep (cmp_rhs)))
+    return;
+  if (TREE_CODE (cmp_lhs) != SSA_NAME)
+    return;
+
+  /* If check_value_one is true, only the phi_args with value '1' will lead
+     to loop exit. Otherwise, only the phi_args with value '0' will lead to
+     loop exit.  */
+  check_value_one = (((integer_onep (cmp_rhs))
+		    ^ (gimple_cond_code (cmp_stmt) == EQ_EXPR))
+		    ^ ((exit_edge->flags & EDGE_TRUE_VALUE) != 0));
+
+  phi_stmt = SSA_NAME_DEF_STMT (cmp_lhs);
+  if (!phi_stmt || gimple_code (phi_stmt) != GIMPLE_PHI)
+    return;
+
+  for (i = 0; i < gimple_phi_num_args (phi_stmt); i++)
+    {
+      edge e1;
+      edge_iterator ei;
+      tree val = gimple_phi_arg_def (phi_stmt, i);
+      edge e = gimple_phi_arg_edge (phi_stmt, i);
+
+      if (!TREE_CONSTANT (val) || !(integer_zerop (val) || integer_onep (val)))
+	continue;
+      if ((check_value_one ^ integer_onep (val)) == 1)
+	continue;
+      if (EDGE_COUNT (e->src->succs) != 1)
+	{
+	  predict_paths_leading_to_edge (e, PRED_LOOP_EXIT, NOT_TAKEN);
+	  continue;
+	}
+
+      FOR_EACH_EDGE (e1, ei, e->src->preds)
+	predict_paths_leading_to_edge (e1, PRED_LOOP_EXIT, NOT_TAKEN);
+    }
+}
+
+/* Predict edge probabilities by exploiting loop structure.  */
+
+static void
+predict_loops (void)
+{
+  struct loop *loop;
+
+  /* Try to predict out blocks in a loop that are not part of a
+     natural loop.  */
+  FOR_EACH_LOOP (loop, 0)
+    {
+      basic_block bb, *bbs;
+      unsigned j, n_exits;
+      vec<edge> exits;
+      struct tree_niter_desc niter_desc;
+      edge ex;
+      struct nb_iter_bound *nb_iter;
+      enum tree_code loop_bound_code = ERROR_MARK;
+      tree loop_bound_step = NULL;
+      tree loop_bound_var = NULL;
+      tree loop_iv_base = NULL;
+      gimple stmt = NULL;
+
+      exits = get_loop_exit_edges (loop);
+      n_exits = exits.length ();
+      if (!n_exits)
+	{
+          exits.release ();
+	  continue;
+	}
+
+      FOR_EACH_VEC_ELT (exits, j, ex)
+	{
+	  tree niter = NULL;
+	  HOST_WIDE_INT nitercst;
+	  int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS);
+	  int probability;
+	  enum br_predictor predictor;
+
+	  predict_extra_loop_exits (ex);
+
+	  if (number_of_iterations_exit (loop, ex, &niter_desc, false, 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)
+	    {
+	      if (tree_fits_uhwi_p (niter)
+		  && max
+		  && compare_tree_int (niter, max - 1) == -1)
+		nitercst = tree_to_uhwi (niter) + 1;
+	      else
+		nitercst = max;
+	      predictor = PRED_LOOP_ITERATIONS;
+	    }
+	  /* 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)
+	    {
+	      nitercst = estimated_stmt_executions_int (loop);
+	      if (nitercst < 0)
+		continue;
+	      if (nitercst > max)
+		nitercst = max;
+
+	      predictor = PRED_LOOP_ITERATIONS_GUESSED;
+	    }
+	  else
+	    continue;
+
+	  /* If the prediction for number of iterations is zero, do not
+	     predict the exit edges.  */
+	  if (nitercst == 0)
+	    continue;
+
+	  probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst);
+	  predict_edge (ex, predictor, probability);
+	}
+      exits.release ();
+
+      /* Find information about loop bound variables.  */
+      for (nb_iter = loop->bounds; nb_iter;
+	   nb_iter = nb_iter->next)
+	if (nb_iter->stmt
+	    && gimple_code (nb_iter->stmt) == GIMPLE_COND)
+	  {
+	    stmt = nb_iter->stmt;
+	    break;
+	  }
+      if (!stmt && last_stmt (loop->header)
+	  && gimple_code (last_stmt (loop->header)) == GIMPLE_COND)
+	stmt = last_stmt (loop->header);
+      if (stmt)
+	is_comparison_with_loop_invariant_p (stmt, loop,
+					     &loop_bound_var,
+					     &loop_bound_code,
+					     &loop_bound_step,
+					     &loop_iv_base);
+
+      bbs = get_loop_body (loop);
+
+      for (j = 0; j < loop->num_nodes; j++)
+	{
+	  int header_found = 0;
+	  edge e;
+	  edge_iterator ei;
+
+	  bb = bbs[j];
+
+	  /* Bypass loop heuristics on continue statement.  These
+	     statements construct loops via "non-loop" constructs
+	     in the source language and are better to be handled
+	     separately.  */
+	  if (predicted_by_p (bb, PRED_CONTINUE))
+	    continue;
+
+	  /* Loop branch heuristics - predict an edge back to a
+	     loop's head as taken.  */
+	  if (bb == loop->latch)
+	    {
+	      e = find_edge (loop->latch, loop->header);
+	      if (e)
+		{
+		  header_found = 1;
+		  predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN);
+		}
+	    }
+
+	  /* Loop exit heuristics - predict an edge exiting the loop if the
+	     conditional has no loop header successors as not taken.  */
+	  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);
+	    }
+	  if (loop_bound_var)
+	    predict_iv_comparison (loop, bb, loop_bound_var, loop_iv_base,
+				   loop_bound_code,
+				   tree_to_shwi (loop_bound_step));
+	}
+
+      /* Free basic blocks from get_loop_body.  */
+      free (bbs);
+    }
+}
+
+/* Attempt to predict probabilities of BB outgoing edges using local
+   properties.  */
+static void
+bb_estimate_probability_locally (basic_block bb)
+{
+  rtx last_insn = BB_END (bb);
+  rtx cond;
+
+  if (! can_predict_insn_p (last_insn))
+    return;
+  cond = get_condition (last_insn, NULL, false, false);
+  if (! cond)
+    return;
+
+  /* Try "pointer heuristic."
+     A comparison ptr == 0 is predicted as false.
+     Similarly, a comparison ptr1 == ptr2 is predicted as false.  */
+  if (COMPARISON_P (cond)
+      && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0)))
+	  || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1)))))
+    {
+      if (GET_CODE (cond) == EQ)
+	predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN);
+      else if (GET_CODE (cond) == NE)
+	predict_insn_def (last_insn, PRED_POINTER, TAKEN);
+    }
+  else
+
+  /* Try "opcode heuristic."
+     EQ tests are usually false and NE tests are usually true. Also,
+     most quantities are positive, so we can make the appropriate guesses
+     about signed comparisons against zero.  */
+    switch (GET_CODE (cond))
+      {
+      case CONST_INT:
+	/* Unconditional branch.  */
+	predict_insn_def (last_insn, PRED_UNCONDITIONAL,
+			  cond == const0_rtx ? NOT_TAKEN : TAKEN);
+	break;
+
+      case EQ:
+      case UNEQ:
+	/* Floating point comparisons appears to behave in a very
+	   unpredictable way because of special role of = tests in
+	   FP code.  */
+	if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0))))
+	  ;
+	/* Comparisons with 0 are often used for booleans and there is
+	   nothing useful to predict about them.  */
+	else if (XEXP (cond, 1) == const0_rtx
+		 || XEXP (cond, 0) == const0_rtx)
+	  ;
+	else
+	  predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, NOT_TAKEN);
+	break;
+
+      case NE:
+      case LTGT:
+	/* Floating point comparisons appears to behave in a very
+	   unpredictable way because of special role of = tests in
+	   FP code.  */
+	if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0))))
+	  ;
+	/* Comparisons with 0 are often used for booleans and there is
+	   nothing useful to predict about them.  */
+	else if (XEXP (cond, 1) == const0_rtx
+		 || XEXP (cond, 0) == const0_rtx)
+	  ;
+	else
+	  predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, TAKEN);
+	break;
+
+      case ORDERED:
+	predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN);
+	break;
+
+      case UNORDERED:
+	predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN);
+	break;
+
+      case LE:
+      case LT:
+	if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx
+	    || XEXP (cond, 1) == constm1_rtx)
+	  predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, NOT_TAKEN);
+	break;
+
+      case GE:
+      case GT:
+	if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx
+	    || XEXP (cond, 1) == constm1_rtx)
+	  predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, TAKEN);
+	break;
+
+      default:
+	break;
+      }
+}
+
+/* Set edge->probability for each successor edge of BB.  */
+void
+guess_outgoing_edge_probabilities (basic_block bb)
+{
+  bb_estimate_probability_locally (bb);
+  combine_predictions_for_insn (BB_END (bb), bb);
+}
+
+static tree expr_expected_value (tree, bitmap, enum br_predictor *predictor);
+
+/* Helper function for expr_expected_value.  */
+
+static tree
+expr_expected_value_1 (tree type, tree op0, enum tree_code code,
+		       tree op1, bitmap visited, enum br_predictor *predictor)
+{
+  gimple def;
+
+  if (predictor)
+    *predictor = PRED_UNCONDITIONAL;
+
+  if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS)
+    {
+      if (TREE_CONSTANT (op0))
+	return op0;
+
+      if (code != SSA_NAME)
+	return NULL_TREE;
+
+      def = SSA_NAME_DEF_STMT (op0);
+
+      /* If we were already here, break the infinite cycle.  */
+      if (!bitmap_set_bit (visited, SSA_NAME_VERSION (op0)))
+	return NULL;
+
+      if (gimple_code (def) == GIMPLE_PHI)
+	{
+	  /* All the arguments of the PHI node must have the same constant
+	     length.  */
+	  int i, n = gimple_phi_num_args (def);
+	  tree val = NULL, new_val;
+
+	  for (i = 0; i < n; i++)
+	    {
+	      tree arg = PHI_ARG_DEF (def, i);
+	      enum br_predictor predictor2;
+
+	      /* If this PHI has itself as an argument, we cannot
+		 determine the string length of this argument.  However,
+		 if we can find an expected constant value for the other
+		 PHI args then we can still be sure that this is
+		 likely a constant.  So be optimistic and just
+		 continue with the next argument.  */
+	      if (arg == PHI_RESULT (def))
+		continue;
+
+	      new_val = expr_expected_value (arg, visited, &predictor2);
+
+	      /* It is difficult to combine value predictors.  Simply assume
+		 that later predictor is weaker and take its prediction.  */
+	      if (predictor && *predictor < predictor2)
+		*predictor = predictor2;
+	      if (!new_val)
+		return NULL;
+	      if (!val)
+		val = new_val;
+	      else if (!operand_equal_p (val, new_val, false))
+		return NULL;
+	    }
+	  return val;
+	}
+      if (is_gimple_assign (def))
+	{
+	  if (gimple_assign_lhs (def) != op0)
+	    return NULL;
+
+	  return expr_expected_value_1 (TREE_TYPE (gimple_assign_lhs (def)),
+					gimple_assign_rhs1 (def),
+					gimple_assign_rhs_code (def),
+					gimple_assign_rhs2 (def),
+					visited, predictor);
+	}
+
+      if (is_gimple_call (def))
+	{
+	  tree decl = gimple_call_fndecl (def);
+	  if (!decl)
+	    {
+	      if (gimple_call_internal_p (def)
+		  && gimple_call_internal_fn (def) == IFN_BUILTIN_EXPECT)
+		{
+		  gcc_assert (gimple_call_num_args (def) == 3);
+		  tree val = gimple_call_arg (def, 0);
+		  if (TREE_CONSTANT (val))
+		    return val;
+		  if (predictor)
+		    {
+		      *predictor = PRED_BUILTIN_EXPECT;
+		      tree val2 = gimple_call_arg (def, 2);
+		      gcc_assert (TREE_CODE (val2) == INTEGER_CST
+				  && tree_fits_uhwi_p (val2)
+				  && tree_to_uhwi (val2) < END_PREDICTORS);
+		      *predictor = (enum br_predictor) tree_to_uhwi (val2);
+		    }
+		  return gimple_call_arg (def, 1);
+		}
+	      return NULL;
+	    }
+	  if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL)
+	    switch (DECL_FUNCTION_CODE (decl))
+	      {
+	      case BUILT_IN_EXPECT:
+		{
+		  tree val;
+		  if (gimple_call_num_args (def) != 2)
+		    return NULL;
+		  val = gimple_call_arg (def, 0);
+		  if (TREE_CONSTANT (val))
+		    return val;
+		  if (predictor)
+		    *predictor = PRED_BUILTIN_EXPECT;
+		  return gimple_call_arg (def, 1);
+		}
+
+	      case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_N:
+	      case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1:
+	      case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2:
+	      case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4:
+	      case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8:
+	      case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16:
+	      case BUILT_IN_ATOMIC_COMPARE_EXCHANGE:
+	      case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N:
+	      case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1:
+	      case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2:
+	      case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4:
+	      case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8:
+	      case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16:
+		/* Assume that any given atomic operation has low contention,
+		   and thus the compare-and-swap operation succeeds.  */
+		if (predictor)
+		  *predictor = PRED_COMPARE_AND_SWAP;
+		return boolean_true_node;
+	    }
+	}
+
+      return NULL;
+    }
+
+  if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS)
+    {
+      tree res;
+      enum br_predictor predictor2;
+      op0 = expr_expected_value (op0, visited, predictor);
+      if (!op0)
+	return NULL;
+      op1 = expr_expected_value (op1, visited, &predictor2);
+      if (predictor && *predictor < predictor2)
+	*predictor = predictor2;
+      if (!op1)
+	return NULL;
+      res = fold_build2 (code, type, op0, op1);
+      if (TREE_CONSTANT (res))
+	return res;
+      return NULL;
+    }
+  if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS)
+    {
+      tree res;
+      op0 = expr_expected_value (op0, visited, predictor);
+      if (!op0)
+	return NULL;
+      res = fold_build1 (code, type, op0);
+      if (TREE_CONSTANT (res))
+	return res;
+      return NULL;
+    }
+  return NULL;
+}
+
+/* Return constant EXPR will likely have at execution time, NULL if unknown.
+   The function is used by builtin_expect branch predictor so the evidence
+   must come from this construct and additional possible constant folding.
+
+   We may want to implement more involved value guess (such as value range
+   propagation based prediction), but such tricks shall go to new
+   implementation.  */
+
+static tree
+expr_expected_value (tree expr, bitmap visited,
+		     enum br_predictor *predictor)
+{
+  enum tree_code code;
+  tree op0, op1;
+
+  if (TREE_CONSTANT (expr))
+    {
+      if (predictor)
+	*predictor = PRED_UNCONDITIONAL;
+      return expr;
+    }
+
+  extract_ops_from_tree (expr, &code, &op0, &op1);
+  return expr_expected_value_1 (TREE_TYPE (expr),
+				op0, code, op1, visited, predictor);
+}
+
+
+/* Get rid of all builtin_expect calls and GIMPLE_PREDICT statements
+   we no longer need.  */
+static unsigned int
+strip_predict_hints (void)
+{
+  basic_block bb;
+  gimple ass_stmt;
+  tree var;
+
+  FOR_EACH_BB_FN (bb, cfun)
+    {
+      gimple_stmt_iterator bi;
+      for (bi = gsi_start_bb (bb); !gsi_end_p (bi);)
+	{
+	  gimple stmt = gsi_stmt (bi);
+
+	  if (gimple_code (stmt) == GIMPLE_PREDICT)
+	    {
+	      gsi_remove (&bi, true);
+	      continue;
+	    }
+	  else if (is_gimple_call (stmt))
+	    {
+	      tree fndecl = gimple_call_fndecl (stmt);
+
+	      if ((fndecl
+		   && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
+		   && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT
+		   && gimple_call_num_args (stmt) == 2)
+		  || (gimple_call_internal_p (stmt)
+		      && gimple_call_internal_fn (stmt) == IFN_BUILTIN_EXPECT))
+		{
+		  var = gimple_call_lhs (stmt);
+		  if (var)
+		    {
+		      ass_stmt
+			= gimple_build_assign (var, gimple_call_arg (stmt, 0));
+		      gsi_replace (&bi, ass_stmt, true);
+		    }
+		  else
+		    {
+		      gsi_remove (&bi, true);
+		      continue;
+		    }
+		}
+	    }
+	  gsi_next (&bi);
+	}
+    }
+  return 0;
+}
+
+/* Predict using opcode of the last statement in basic block.  */
+static void
+tree_predict_by_opcode (basic_block bb)
+{
+  gimple stmt = last_stmt (bb);
+  edge then_edge;
+  tree op0, op1;
+  tree type;
+  tree val;
+  enum tree_code cmp;
+  bitmap visited;
+  edge_iterator ei;
+  enum br_predictor predictor;
+
+  if (!stmt || gimple_code (stmt) != GIMPLE_COND)
+    return;
+  FOR_EACH_EDGE (then_edge, ei, bb->succs)
+    if (then_edge->flags & EDGE_TRUE_VALUE)
+      break;
+  op0 = gimple_cond_lhs (stmt);
+  op1 = gimple_cond_rhs (stmt);
+  cmp = gimple_cond_code (stmt);
+  type = TREE_TYPE (op0);
+  visited = BITMAP_ALLOC (NULL);
+  val = expr_expected_value_1 (boolean_type_node, op0, cmp, op1, visited,
+			       &predictor);
+  BITMAP_FREE (visited);
+  if (val && TREE_CODE (val) == INTEGER_CST)
+    {
+      if (predictor == PRED_BUILTIN_EXPECT)
+	{
+	  int percent = PARAM_VALUE (BUILTIN_EXPECT_PROBABILITY);
+
+	  gcc_assert (percent >= 0 && percent <= 100);
+	  if (integer_zerop (val))
+	    percent = 100 - percent;
+	  predict_edge (then_edge, PRED_BUILTIN_EXPECT, HITRATE (percent));
+	}
+      else
+	predict_edge (then_edge, predictor,
+		      integer_zerop (val) ? NOT_TAKEN : TAKEN);
+    }
+  /* Try "pointer heuristic."
+     A comparison ptr == 0 is predicted as false.
+     Similarly, a comparison ptr1 == ptr2 is predicted as false.  */
+  if (POINTER_TYPE_P (type))
+    {
+      if (cmp == EQ_EXPR)
+	predict_edge_def (then_edge, PRED_TREE_POINTER, NOT_TAKEN);
+      else if (cmp == NE_EXPR)
+	predict_edge_def (then_edge, PRED_TREE_POINTER, TAKEN);
+    }
+  else
+
+  /* Try "opcode heuristic."
+     EQ tests are usually false and NE tests are usually true. Also,
+     most quantities are positive, so we can make the appropriate guesses
+     about signed comparisons against zero.  */
+    switch (cmp)
+      {
+      case EQ_EXPR:
+      case UNEQ_EXPR:
+	/* Floating point comparisons appears to behave in a very
+	   unpredictable way because of special role of = tests in
+	   FP code.  */
+	if (FLOAT_TYPE_P (type))
+	  ;
+	/* Comparisons with 0 are often used for booleans and there is
+	   nothing useful to predict about them.  */
+	else if (integer_zerop (op0) || integer_zerop (op1))
+	  ;
+	else
+	  predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, NOT_TAKEN);
+	break;
+
+      case NE_EXPR:
+      case LTGT_EXPR:
+	/* Floating point comparisons appears to behave in a very
+	   unpredictable way because of special role of = tests in
+	   FP code.  */
+	if (FLOAT_TYPE_P (type))
+	  ;
+	/* Comparisons with 0 are often used for booleans and there is
+	   nothing useful to predict about them.  */
+	else if (integer_zerop (op0)
+		 || integer_zerop (op1))
+	  ;
+	else
+	  predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, TAKEN);
+	break;
+
+      case ORDERED_EXPR:
+	predict_edge_def (then_edge, PRED_TREE_FPOPCODE, TAKEN);
+	break;
+
+      case UNORDERED_EXPR:
+	predict_edge_def (then_edge, PRED_TREE_FPOPCODE, NOT_TAKEN);
+	break;
+
+      case LE_EXPR:
+      case LT_EXPR:
+	if (integer_zerop (op1)
+	    || integer_onep (op1)
+	    || integer_all_onesp (op1)
+	    || real_zerop (op1)
+	    || real_onep (op1)
+	    || real_minus_onep (op1))
+	  predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, NOT_TAKEN);
+	break;
+
+      case GE_EXPR:
+      case GT_EXPR:
+	if (integer_zerop (op1)
+	    || integer_onep (op1)
+	    || integer_all_onesp (op1)
+	    || real_zerop (op1)
+	    || real_onep (op1)
+	    || real_minus_onep (op1))
+	  predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, TAKEN);
+	break;
+
+      default:
+	break;
+      }
+}
+
+/* Try to guess whether the value of return means error code.  */
+
+static enum br_predictor
+return_prediction (tree val, enum prediction *prediction)
+{
+  /* VOID.  */
+  if (!val)
+    return PRED_NO_PREDICTION;
+  /* Different heuristics for pointers and scalars.  */
+  if (POINTER_TYPE_P (TREE_TYPE (val)))
+    {
+      /* NULL is usually not returned.  */
+      if (integer_zerop (val))
+	{
+	  *prediction = NOT_TAKEN;
+	  return PRED_NULL_RETURN;
+	}
+    }
+  else if (INTEGRAL_TYPE_P (TREE_TYPE (val)))
+    {
+      /* Negative return values are often used to indicate
+         errors.  */
+      if (TREE_CODE (val) == INTEGER_CST
+	  && tree_int_cst_sgn (val) < 0)
+	{
+	  *prediction = NOT_TAKEN;
+	  return PRED_NEGATIVE_RETURN;
+	}
+      /* Constant return values seems to be commonly taken.
+         Zero/one often represent booleans so exclude them from the
+	 heuristics.  */
+      if (TREE_CONSTANT (val)
+	  && (!integer_zerop (val) && !integer_onep (val)))
+	{
+	  *prediction = TAKEN;
+	  return PRED_CONST_RETURN;
+	}
+    }
+  return PRED_NO_PREDICTION;
+}
+
+/* Find the basic block with return expression and look up for possible
+   return value trying to apply RETURN_PREDICTION heuristics.  */
+static void
+apply_return_prediction (void)
+{
+  gimple return_stmt = NULL;
+  tree return_val;
+  edge e;
+  gimple phi;
+  int phi_num_args, i;
+  enum br_predictor pred;
+  enum prediction direction;
+  edge_iterator ei;
+
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
+    {
+      return_stmt = last_stmt (e->src);
+      if (return_stmt
+	  && gimple_code (return_stmt) == GIMPLE_RETURN)
+	break;
+    }
+  if (!e)
+    return;
+  return_val = gimple_return_retval (return_stmt);
+  if (!return_val)
+    return;
+  if (TREE_CODE (return_val) != SSA_NAME
+      || !SSA_NAME_DEF_STMT (return_val)
+      || gimple_code (SSA_NAME_DEF_STMT (return_val)) != GIMPLE_PHI)
+    return;
+  phi = SSA_NAME_DEF_STMT (return_val);
+  phi_num_args = gimple_phi_num_args (phi);
+  pred = return_prediction (PHI_ARG_DEF (phi, 0), &direction);
+
+  /* Avoid the degenerate case where all return values form the function
+     belongs to same category (ie they are all positive constants)
+     so we can hardly say something about them.  */
+  for (i = 1; i < phi_num_args; i++)
+    if (pred != return_prediction (PHI_ARG_DEF (phi, i), &direction))
+      break;
+  if (i != phi_num_args)
+    for (i = 0; i < phi_num_args; i++)
+      {
+	pred = return_prediction (PHI_ARG_DEF (phi, i), &direction);
+	if (pred != PRED_NO_PREDICTION)
+	  predict_paths_leading_to_edge (gimple_phi_arg_edge (phi, i), pred,
+				         direction);
+      }
+}
+
+/* Look for basic block that contains unlikely to happen events
+   (such as noreturn calls) and mark all paths leading to execution
+   of this basic blocks as unlikely.  */
+
+static void
+tree_bb_level_predictions (void)
+{
+  basic_block bb;
+  bool has_return_edges = false;
+  edge e;
+  edge_iterator ei;
+
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
+    if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH)))
+      {
+        has_return_edges = true;
+	break;
+      }
+
+  apply_return_prediction ();
+
+  FOR_EACH_BB_FN (bb, cfun)
+    {
+      gimple_stmt_iterator gsi;
+
+      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  gimple stmt = gsi_stmt (gsi);
+	  tree decl;
+
+	  if (is_gimple_call (stmt))
+	    {
+	      if ((gimple_call_flags (stmt) & ECF_NORETURN)
+	          && has_return_edges)
+		predict_paths_leading_to (bb, PRED_NORETURN,
+					  NOT_TAKEN);
+	      decl = gimple_call_fndecl (stmt);
+	      if (decl
+		  && lookup_attribute ("cold",
+				       DECL_ATTRIBUTES (decl)))
+		predict_paths_leading_to (bb, PRED_COLD_FUNCTION,
+					  NOT_TAKEN);
+	    }
+	  else if (gimple_code (stmt) == GIMPLE_PREDICT)
+	    {
+	      predict_paths_leading_to (bb, gimple_predict_predictor (stmt),
+					gimple_predict_outcome (stmt));
+	      /* Keep GIMPLE_PREDICT around so early inlining will propagate
+	         hints to callers.  */
+	    }
+	}
+    }
+}
+
+#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 for basic block BB.  */
+
+static void
+tree_estimate_probability_bb (basic_block bb)
+{
+  edge e;
+  edge_iterator ei;
+  gimple last;
+
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    {
+      /* Predict edges to user labels with attributes.  */
+      if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
+	{
+	  gimple_stmt_iterator gi;
+	  for (gi = gsi_start_bb (e->dest); !gsi_end_p (gi); gsi_next (&gi))
+	    {
+	      gimple stmt = gsi_stmt (gi);
+	      tree decl;
+
+	      if (gimple_code (stmt) != GIMPLE_LABEL)
+		break;
+	      decl = gimple_label_label (stmt);
+	      if (DECL_ARTIFICIAL (decl))
+		continue;
+
+	      /* Finally, we have a user-defined label.  */
+	      if (lookup_attribute ("cold", DECL_ATTRIBUTES (decl)))
+		predict_edge_def (e, PRED_COLD_LABEL, NOT_TAKEN);
+	      else if (lookup_attribute ("hot", DECL_ATTRIBUTES (decl)))
+		predict_edge_def (e, PRED_HOT_LABEL, TAKEN);
+	    }
+	}
+
+      /* Predict early returns to be probable, as we've already taken
+	 care for error returns and other cases are often used for
+	 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_FOR_FN (cfun)
+	  && single_succ_p (e->dest)
+	  && single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR_FOR_FN (cfun)
+	  && (last = last_stmt (e->dest)) != NULL
+	  && gimple_code (last) == GIMPLE_RETURN)
+	{
+	  edge e1;
+	  edge_iterator ei1;
+
+	  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,
+	 but it doesn't postdominate us).  */
+      if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) && e->dest != bb
+	  && dominated_by_p (CDI_DOMINATORS, e->dest, e->src)
+	  && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest))
+	{
+	  gimple_stmt_iterator bi;
+
+	  /* 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 (bi = gsi_start_bb (e->dest); !gsi_end_p (bi);
+	       gsi_next (&bi))
+	    {
+	      gimple stmt = gsi_stmt (bi);
+	      if (is_gimple_call (stmt)
+		  /* Constant and pure calls are hardly used to signalize
+		     something exceptional.  */
+		  && gimple_has_side_effects (stmt))
+		{
+		  predict_edge_def (e, PRED_CALL, NOT_TAKEN);
+		  break;
+		}
+	    }
+	}
+    }
+  tree_predict_by_opcode (bb);
+}
+
+/* Predict branch probabilities and estimate profile of the tree CFG.
+   This function can be called from the loop optimizers to recompute
+   the profile information.  */
+
+void
+tree_estimate_probability (void)
+{
+  basic_block bb;
+
+  add_noreturn_fake_exit_edges ();
+  connect_infinite_loops_to_exit ();
+  /* We use loop_niter_by_eval, which requires that the loops have
+     preheaders.  */
+  create_preheaders (CP_SIMPLE_PREHEADERS);
+  calculate_dominance_info (CDI_POST_DOMINATORS);
+
+  bb_predictions = pointer_map_create ();
+  tree_bb_level_predictions ();
+  record_loop_exits ();
+
+  if (number_of_loops (cfun) > 1)
+    predict_loops ();
+
+  FOR_EACH_BB_FN (bb, cfun)
+    tree_estimate_probability_bb (bb);
+
+  FOR_EACH_BB_FN (bb, cfun)
+    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;
+
+  estimate_bb_frequencies (false);
+  free_dominance_info (CDI_POST_DOMINATORS);
+  remove_fake_exit_edges ();
+}
+
+/* Predict branch probabilities and estimate profile of the tree CFG.
+   This is the driver function for PASS_PROFILE.  */
+
+static unsigned int
+tree_estimate_probability_driver (void)
+{
+  unsigned nb_loops;
+
+  loop_optimizer_init (LOOPS_NORMAL);
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    flow_loops_dump (dump_file, NULL, 0);
+
+  mark_irreducible_loops ();
+
+  nb_loops = number_of_loops (cfun);
+  if (nb_loops > 1)
+    scev_initialize ();
+
+  tree_estimate_probability ();
+
+  if (nb_loops > 1)
+    scev_finalize ();
+
+  loop_optimizer_finalize ();
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    gimple_dump_cfg (dump_file, dump_flags);
+  if (profile_status_for_fn (cfun) == PROFILE_ABSENT)
+    profile_status_for_fn (cfun) = PROFILE_GUESSED;
+  return 0;
+}
+
+/* Predict edges to successors of CUR whose sources are not postdominated by
+   BB by PRED and recurse to all postdominators.  */
+
+static void
+predict_paths_for_bb (basic_block cur, basic_block bb,
+		      enum br_predictor pred,
+		      enum prediction taken,
+		      bitmap visited)
+{
+  edge e;
+  edge_iterator ei;
+  basic_block son;
+
+  /* We are looking for all edges forming edge cut induced by
+     set of all blocks postdominated by BB.  */
+  FOR_EACH_EDGE (e, ei, cur->preds)
+    if (e->src->index >= NUM_FIXED_BLOCKS
+	&& !dominated_by_p (CDI_POST_DOMINATORS, e->src, bb))
+    {
+      edge e2;
+      edge_iterator ei2;
+      bool found = false;
+
+      /* Ignore fake edges and eh, we predict them as not taken anyway.  */
+      if (e->flags & (EDGE_EH | EDGE_FAKE))
+	continue;
+      gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb));
+
+      /* 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
+	    && !(e2->flags & (EDGE_EH | EDGE_FAKE))
+	    && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb))
+	  {
+	    found = true;
+	    break;
+	  }
+
+      /* If there is non-abnormal path leaving e->src, predict edge
+	 using predictor.  Otherwise we need to look for paths
+	 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 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, visited);
+}
+
+/* Sets branch probabilities according to PREDiction and
+   FLAGS.  */
+
+static void
+predict_paths_leading_to (basic_block bb, enum br_predictor pred,
+			  enum prediction 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.  */
+
+static void
+predict_paths_leading_to_edge (edge e, enum br_predictor pred,
+			       enum prediction taken)
+{
+  bool has_nonloop_edge = false;
+  edge_iterator ei;
+  edge e2;
+
+  basic_block bb = e->src;
+  FOR_EACH_EDGE (e2, ei, bb->succs)
+    if (e2->dest != e->src && e2->dest != e->dest
+	&& !(e->flags & (EDGE_EH | EDGE_FAKE))
+	&& !dominated_by_p (CDI_POST_DOMINATORS, e->src, e2->dest))
+      {
+	has_nonloop_edge = true;
+	break;
+      }
+  if (!has_nonloop_edge)
+    {
+      bitmap visited = BITMAP_ALLOC (NULL);
+      predict_paths_for_bb (bb, bb, pred, taken, visited);
+      BITMAP_FREE (visited);
+    }
+  else
+    predict_edge_def (e, pred, taken);
+}
+
+/* This is used to carry information about basic blocks.  It is
+   attached to the AUX field of the standard CFG block.  */
+
+typedef struct block_info_def
+{
+  /* Estimated frequency of execution of basic_block.  */
+  sreal frequency;
+
+  /* To keep queue of basic blocks to process.  */
+  basic_block next;
+
+  /* Number of predecessors we need to visit first.  */
+  int npredecessors;
+} *block_info;
+
+/* Similar information for edges.  */
+typedef struct edge_info_def
+{
+  /* In case edge is a loopback edge, the probability edge will be reached
+     in case header is.  Estimated number of iterations of the loop can be
+     then computed as 1 / (1 - back_edge_prob).  */
+  sreal back_edge_prob;
+  /* True if the edge is a loopback edge in the natural loop.  */
+  unsigned int back_edge:1;
+} *edge_info;
+
+#define BLOCK_INFO(B)	((block_info) (B)->aux)
+#define EDGE_INFO(E)	((edge_info) (E)->aux)
+
+/* Helper function for estimate_bb_frequencies.
+   Propagate the frequencies in blocks marked in
+   TOVISIT, starting in HEAD.  */
+
+static void
+propagate_freq (basic_block head, bitmap tovisit)
+{
+  basic_block bb;
+  basic_block last;
+  unsigned i;
+  edge e;
+  basic_block nextbb;
+  bitmap_iterator bi;
+
+  /* For each basic block we need to visit count number of his predecessors
+     we need to visit first.  */
+  EXECUTE_IF_SET_IN_BITMAP (tovisit, 0, i, bi)
+    {
+      edge_iterator ei;
+      int count = 0;
+
+      bb = BASIC_BLOCK_FOR_FN (cfun, i);
+
+      FOR_EACH_EDGE (e, ei, bb->preds)
+	{
+	  bool visit = bitmap_bit_p (tovisit, e->src->index);
+
+	  if (visit && !(e->flags & EDGE_DFS_BACK))
+	    count++;
+	  else if (visit && dump_file && !EDGE_INFO (e)->back_edge)
+	    fprintf (dump_file,
+		     "Irreducible region hit, ignoring edge to %i->%i\n",
+		     e->src->index, bb->index);
+	}
+      BLOCK_INFO (bb)->npredecessors = count;
+      /* When function never returns, we will never process exit block.  */
+      if (!count && bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
+	bb->count = bb->frequency = 0;
+    }
+
+  memcpy (&BLOCK_INFO (head)->frequency, &real_one, sizeof (real_one));
+  last = head;
+  for (bb = head; bb; bb = nextbb)
+    {
+      edge_iterator ei;
+      sreal cyclic_probability, frequency;
+
+      memcpy (&cyclic_probability, &real_zero, sizeof (real_zero));
+      memcpy (&frequency, &real_zero, sizeof (real_zero));
+
+      nextbb = BLOCK_INFO (bb)->next;
+      BLOCK_INFO (bb)->next = NULL;
+
+      /* Compute frequency of basic block.  */
+      if (bb != head)
+	{
+#ifdef ENABLE_CHECKING
+	  FOR_EACH_EDGE (e, ei, bb->preds)
+	    gcc_assert (!bitmap_bit_p (tovisit, e->src->index)
+			|| (e->flags & EDGE_DFS_BACK));
+#endif
+
+	  FOR_EACH_EDGE (e, ei, bb->preds)
+	    if (EDGE_INFO (e)->back_edge)
+	      {
+		sreal_add (&cyclic_probability, &cyclic_probability,
+			   &EDGE_INFO (e)->back_edge_prob);
+	      }
+	    else if (!(e->flags & EDGE_DFS_BACK))
+	      {
+		sreal tmp;
+
+		/*  frequency += (e->probability
+				  * BLOCK_INFO (e->src)->frequency /
+				  REG_BR_PROB_BASE);  */
+
+		sreal_init (&tmp, e->probability, 0);
+		sreal_mul (&tmp, &tmp, &BLOCK_INFO (e->src)->frequency);
+		sreal_mul (&tmp, &tmp, &real_inv_br_prob_base);
+		sreal_add (&frequency, &frequency, &tmp);
+	      }
+
+	  if (sreal_compare (&cyclic_probability, &real_zero) == 0)
+	    {
+	      memcpy (&BLOCK_INFO (bb)->frequency, &frequency,
+		      sizeof (frequency));
+	    }
+	  else
+	    {
+	      if (sreal_compare (&cyclic_probability, &real_almost_one) > 0)
+		{
+		  memcpy (&cyclic_probability, &real_almost_one,
+			  sizeof (real_almost_one));
+		}
+
+	      /* BLOCK_INFO (bb)->frequency = frequency
+					      / (1 - cyclic_probability) */
+
+	      sreal_sub (&cyclic_probability, &real_one, &cyclic_probability);
+	      sreal_div (&BLOCK_INFO (bb)->frequency,
+			 &frequency, &cyclic_probability);
+	    }
+	}
+
+      bitmap_clear_bit (tovisit, bb->index);
+
+      e = find_edge (bb, head);
+      if (e)
+	{
+	  sreal tmp;
+
+	  /* EDGE_INFO (e)->back_edge_prob
+	     = ((e->probability * BLOCK_INFO (bb)->frequency)
+	     / REG_BR_PROB_BASE); */
+
+	  sreal_init (&tmp, e->probability, 0);
+	  sreal_mul (&tmp, &tmp, &BLOCK_INFO (bb)->frequency);
+	  sreal_mul (&EDGE_INFO (e)->back_edge_prob,
+		     &tmp, &real_inv_br_prob_base);
+	}
+
+      /* Propagate to successor blocks.  */
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	if (!(e->flags & EDGE_DFS_BACK)
+	    && BLOCK_INFO (e->dest)->npredecessors)
+	  {
+	    BLOCK_INFO (e->dest)->npredecessors--;
+	    if (!BLOCK_INFO (e->dest)->npredecessors)
+	      {
+		if (!nextbb)
+		  nextbb = e->dest;
+		else
+		  BLOCK_INFO (last)->next = e->dest;
+
+		last = e->dest;
+	      }
+	  }
+    }
+}
+
+/* Estimate frequencies in loops at same nest level.  */
+
+static void
+estimate_loops_at_level (struct loop *first_loop)
+{
+  struct loop *loop;
+
+  for (loop = first_loop; loop; loop = loop->next)
+    {
+      edge e;
+      basic_block *bbs;
+      unsigned i;
+      bitmap tovisit = BITMAP_ALLOC (NULL);
+
+      estimate_loops_at_level (loop->inner);
+
+      /* 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);
+      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 (cfun) > 1)
+    estimate_loops_at_level (current_loops->tree_root->inner);
+
+  /* Now propagate the frequencies through all the blocks.  */
+  FOR_ALL_BB_FN (bb, cfun)
+    {
+      bitmap_set_bit (tovisit, bb->index);
+    }
+  propagate_freq (ENTRY_BLOCK_PTR_FOR_FN (cfun), tovisit);
+  BITMAP_FREE (tovisit);
+}
+
+/* Drop the profile for NODE to guessed, and update its frequency based on
+   whether it is expected to be hot given the CALL_COUNT.  */
+
+static void
+drop_profile (struct cgraph_node *node, gcov_type call_count)
+{
+  struct function *fn = DECL_STRUCT_FUNCTION (node->decl);
+  /* In the case where this was called by another function with a
+     dropped profile, call_count will be 0. Since there are no
+     non-zero call counts to this function, we don't know for sure
+     whether it is hot, and therefore it will be marked normal below.  */
+  bool hot = maybe_hot_count_p (NULL, call_count);
+
+  if (dump_file)
+    fprintf (dump_file,
+             "Dropping 0 profile for %s/%i. %s based on calls.\n",
+             node->name (), node->order,
+             hot ? "Function is hot" : "Function is normal");
+  /* We only expect to miss profiles for functions that are reached
+     via non-zero call edges in cases where the function may have
+     been linked from another module or library (COMDATs and extern
+     templates). See the comments below for handle_missing_profiles.
+     Also, only warn in cases where the missing counts exceed the
+     number of training runs. In certain cases with an execv followed
+     by a no-return call the profile for the no-return call is not
+     dumped and there can be a mismatch.  */
+  if (!DECL_COMDAT (node->decl) && !DECL_EXTERNAL (node->decl)
+      && call_count > profile_info->runs)
+    {
+      if (flag_profile_correction)
+        {
+          if (dump_file)
+            fprintf (dump_file,
+                     "Missing counts for called function %s/%i\n",
+                     node->name (), node->order);
+        }
+      else
+        warning (0, "Missing counts for called function %s/%i",
+                 node->name (), node->order);
+    }
+
+  profile_status_for_fn (fn)
+      = (flag_guess_branch_prob ? PROFILE_GUESSED : PROFILE_ABSENT);
+  node->frequency
+      = hot ? NODE_FREQUENCY_HOT : NODE_FREQUENCY_NORMAL;
+}
+
+/* In the case of COMDAT routines, multiple object files will contain the same
+   function and the linker will select one for the binary. In that case
+   all the other copies from the profile instrument binary will be missing
+   profile counts. Look for cases where this happened, due to non-zero
+   call counts going to 0-count functions, and drop the profile to guessed
+   so that we can use the estimated probabilities and avoid optimizing only
+   for size.
+   
+   The other case where the profile may be missing is when the routine
+   is not going to be emitted to the object file, e.g. for "extern template"
+   class methods. Those will be marked DECL_EXTERNAL. Emit a warning in
+   all other cases of non-zero calls to 0-count functions.  */
+
+void
+handle_missing_profiles (void)
+{
+  struct cgraph_node *node;
+  int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION);
+  vec<struct cgraph_node *> worklist;
+  worklist.create (64);
+
+  /* See if 0 count function has non-0 count callers.  In this case we
+     lost some profile.  Drop its function profile to PROFILE_GUESSED.  */
+  FOR_EACH_DEFINED_FUNCTION (node)
+    {
+      struct cgraph_edge *e;
+      gcov_type call_count = 0;
+      gcov_type max_tp_first_run = 0;
+      struct function *fn = DECL_STRUCT_FUNCTION (node->decl);
+
+      if (node->count)
+        continue;
+      for (e = node->callers; e; e = e->next_caller)
+      {
+        call_count += e->count;
+
+	if (e->caller->tp_first_run > max_tp_first_run)
+	  max_tp_first_run = e->caller->tp_first_run;
+      }
+
+      /* If time profile is missing, let assign the maximum that comes from
+	 caller functions.  */
+      if (!node->tp_first_run && max_tp_first_run)
+	node->tp_first_run = max_tp_first_run + 1;
+
+      if (call_count
+          && fn && fn->cfg
+          && (call_count * unlikely_count_fraction >= profile_info->runs))
+        {
+          drop_profile (node, call_count);
+          worklist.safe_push (node);
+        }
+    }
+
+  /* Propagate the profile dropping to other 0-count COMDATs that are
+     potentially called by COMDATs we already dropped the profile on.  */
+  while (worklist.length () > 0)
+    {
+      struct cgraph_edge *e;
+
+      node = worklist.pop ();
+      for (e = node->callees; e; e = e->next_caller)
+        {
+          struct cgraph_node *callee = e->callee;
+          struct function *fn = DECL_STRUCT_FUNCTION (callee->decl);
+
+          if (callee->count > 0)
+            continue;
+          if (DECL_COMDAT (callee->decl) && fn && fn->cfg
+              && profile_status_for_fn (fn) == PROFILE_READ)
+            {
+              drop_profile (node, 0);
+              worklist.safe_push (callee);
+            }
+        }
+    }
+  worklist.release ();
+}
+
+/* Convert counts measured by profile driven feedback to frequencies.
+   Return nonzero iff there was any nonzero execution count.  */
+
+int
+counts_to_freqs (void)
+{
+  gcov_type count_max, true_count_max = 0;
+  basic_block bb;
+
+  /* Don't overwrite the estimated frequencies when the profile for
+     the function is missing.  We may drop this function PROFILE_GUESSED
+     later in drop_profile ().  */
+  if (!ENTRY_BLOCK_PTR_FOR_FN (cfun)->count)
+    return 0;
+
+  FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
+    true_count_max = MAX (bb->count, true_count_max);
+
+  count_max = MAX (true_count_max, 1);
+  FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
+    bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max;
+
+  return true_count_max;
+}
+
+/* Return true if function is likely to be expensive, so there is no point to
+   optimize performance of prologue, epilogue or do inlining at the expense
+   of code size growth.  THRESHOLD is the limit of number of instructions
+   function can execute at average to be still considered not expensive.  */
+
+bool
+expensive_function_p (int threshold)
+{
+  unsigned int sum = 0;
+  basic_block bb;
+  unsigned int limit;
+
+  /* We can not compute accurately for large thresholds due to scaled
+     frequencies.  */
+  gcc_assert (threshold <= BB_FREQ_MAX);
+
+  /* Frequencies are out of range.  This either means that function contains
+     internal loop executing more than BB_FREQ_MAX times or profile feedback
+     is available and function has not been executed at all.  */
+  if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency == 0)
+    return true;
+
+  /* Maximally BB_FREQ_MAX^2 so overflow won't happen.  */
+  limit = ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency * threshold;
+  FOR_EACH_BB_FN (bb, cfun)
+    {
+      rtx insn;
+
+      FOR_BB_INSNS (bb, insn)
+	if (active_insn_p (insn))
+	  {
+	    sum += bb->frequency;
+	    if (sum > limit)
+	      return true;
+	}
+    }
+
+  return false;
+}
+
+/* Estimate and propagate basic block frequencies using the given branch
+   probabilities.  If FORCE is true, the frequencies are used to estimate
+   the counts even when there are already non-zero profile counts.  */
+
+void
+estimate_bb_frequencies (bool force)
+{
+  basic_block bb;
+  sreal freq_max;
+
+  if (force || profile_status_for_fn (cfun) != PROFILE_READ || !counts_to_freqs ())
+    {
+      static int real_values_initialized = 0;
+
+      if (!real_values_initialized)
+        {
+	  real_values_initialized = 1;
+	  sreal_init (&real_zero, 0, 0);
+	  sreal_init (&real_one, 1, 0);
+	  sreal_init (&real_br_prob_base, REG_BR_PROB_BASE, 0);
+	  sreal_init (&real_bb_freq_max, BB_FREQ_MAX, 0);
+	  sreal_init (&real_one_half, 1, -1);
+	  sreal_div (&real_inv_br_prob_base, &real_one, &real_br_prob_base);
+	  sreal_sub (&real_almost_one, &real_one, &real_inv_br_prob_base);
+	}
+
+      mark_dfs_back_edges ();
+
+      single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->probability =
+	 REG_BR_PROB_BASE;
+
+      /* Set up block info for each basic block.  */
+      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_FOR_FN (cfun), NULL, next_bb)
+	{
+	  edge e;
+	  edge_iterator ei;
+
+	  FOR_EACH_EDGE (e, ei, bb->succs)
+	    {
+	      sreal_init (&EDGE_INFO (e)->back_edge_prob, e->probability, 0);
+	      sreal_mul (&EDGE_INFO (e)->back_edge_prob,
+			 &EDGE_INFO (e)->back_edge_prob,
+			 &real_inv_br_prob_base);
+	    }
+	}
+
+      /* First compute frequencies locally for each loop from innermost
+         to outermost to examine frequencies for back edges.  */
+      estimate_loops ();
+
+      memcpy (&freq_max, &real_zero, sizeof (real_zero));
+      FOR_EACH_BB_FN (bb, cfun)
+	if (sreal_compare (&freq_max, &BLOCK_INFO (bb)->frequency) < 0)
+	  memcpy (&freq_max, &BLOCK_INFO (bb)->frequency, sizeof (freq_max));
+
+      sreal_div (&freq_max, &real_bb_freq_max, &freq_max);
+      FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
+	{
+	  sreal tmp;
+
+	  sreal_mul (&tmp, &BLOCK_INFO (bb)->frequency, &freq_max);
+	  sreal_add (&tmp, &tmp, &real_one_half);
+	  bb->frequency = sreal_to_int (&tmp);
+	}
+
+      free_aux_for_blocks ();
+      free_aux_for_edges ();
+    }
+  compute_function_frequency ();
+}
+
+/* Decide whether function is hot, cold or unlikely executed.  */
+void
+compute_function_frequency (void)
+{
+  basic_block bb;
+  struct cgraph_node *node = cgraph_get_node (current_function_decl);
+
+  if (DECL_STATIC_CONSTRUCTOR (current_function_decl)
+      || MAIN_NAME_P (DECL_NAME (current_function_decl)))
+    node->only_called_at_startup = true;
+  if (DECL_STATIC_DESTRUCTOR (current_function_decl))
+    node->only_called_at_exit = true;
+
+  if (profile_status_for_fn (cfun) != PROFILE_READ)
+    {
+      int flags = flags_from_decl_or_type (current_function_decl);
+      if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl))
+	  != NULL)
+        node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED;
+      else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl))
+	       != NULL)
+        node->frequency = NODE_FREQUENCY_HOT;
+      else if (flags & ECF_NORETURN)
+        node->frequency = NODE_FREQUENCY_EXECUTED_ONCE;
+      else if (MAIN_NAME_P (DECL_NAME (current_function_decl)))
+        node->frequency = NODE_FREQUENCY_EXECUTED_ONCE;
+      else if (DECL_STATIC_CONSTRUCTOR (current_function_decl)
+	       || DECL_STATIC_DESTRUCTOR (current_function_decl))
+        node->frequency = NODE_FREQUENCY_EXECUTED_ONCE;
+      return;
+    }
+
+  /* Only first time try to drop function into unlikely executed.
+     After inlining the roundoff errors may confuse us.
+     Ipa-profile pass will drop functions only called from unlikely
+     functions to unlikely and that is most of what we care about.  */
+  if (!cfun->after_inlining)
+    node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED;
+  FOR_EACH_BB_FN (bb, cfun)
+    {
+      if (maybe_hot_bb_p (cfun, bb))
+	{
+	  node->frequency = NODE_FREQUENCY_HOT;
+	  return;
+	}
+      if (!probably_never_executed_bb_p (cfun, bb))
+	node->frequency = NODE_FREQUENCY_NORMAL;
+    }
+}
+
+static bool
+gate_estimate_probability (void)
+{
+  return flag_guess_branch_prob;
+}
+
+/* Build PREDICT_EXPR.  */
+tree
+build_predict_expr (enum br_predictor predictor, enum prediction taken)
+{
+  tree t = build1 (PREDICT_EXPR, void_type_node,
+		   build_int_cst (integer_type_node, predictor));
+  SET_PREDICT_EXPR_OUTCOME (t, taken);
+  return t;
+}
+
+const char *
+predictor_name (enum br_predictor predictor)
+{
+  return predictor_info[predictor].name;
+}
+
+namespace {
+
+const pass_data pass_data_profile =
+{
+  GIMPLE_PASS, /* type */
+  "profile_estimate", /* name */
+  OPTGROUP_NONE, /* optinfo_flags */
+  true, /* has_gate */
+  true, /* has_execute */
+  TV_BRANCH_PROB, /* tv_id */
+  PROP_cfg, /* properties_required */
+  0, /* properties_provided */
+  0, /* properties_destroyed */
+  0, /* todo_flags_start */
+  TODO_verify_ssa, /* todo_flags_finish */
+};
+
+class pass_profile : public gimple_opt_pass
+{
+public:
+  pass_profile (gcc::context *ctxt)
+    : gimple_opt_pass (pass_data_profile, ctxt)
+  {}
+
+  /* opt_pass methods: */
+  bool gate () { return gate_estimate_probability (); }
+  unsigned int execute () { return tree_estimate_probability_driver (); }
+
+}; // class pass_profile
+
+} // anon namespace
+
+gimple_opt_pass *
+make_pass_profile (gcc::context *ctxt)
+{
+  return new pass_profile (ctxt);
+}
+
+namespace {
+
+const pass_data pass_data_strip_predict_hints =
+{
+  GIMPLE_PASS, /* type */
+  "*strip_predict_hints", /* name */
+  OPTGROUP_NONE, /* optinfo_flags */
+  false, /* has_gate */
+  true, /* has_execute */
+  TV_BRANCH_PROB, /* tv_id */
+  PROP_cfg, /* properties_required */
+  0, /* properties_provided */
+  0, /* properties_destroyed */
+  0, /* todo_flags_start */
+  TODO_verify_ssa, /* todo_flags_finish */
+};
+
+class pass_strip_predict_hints : public gimple_opt_pass
+{
+public:
+  pass_strip_predict_hints (gcc::context *ctxt)
+    : gimple_opt_pass (pass_data_strip_predict_hints, ctxt)
+  {}
+
+  /* opt_pass methods: */
+  opt_pass * clone () { return new pass_strip_predict_hints (m_ctxt); }
+  unsigned int execute () { return strip_predict_hints (); }
+
+}; // class pass_strip_predict_hints
+
+} // anon namespace
+
+gimple_opt_pass *
+make_pass_strip_predict_hints (gcc::context *ctxt)
+{
+  return new pass_strip_predict_hints (ctxt);
+}
+
+/* Rebuild function frequencies.  Passes are in general expected to
+   maintain profile by hand, however in some cases this is not possible:
+   for example when inlining several functions with loops freuqencies might run
+   out of scale and thus needs to be recomputed.  */
+
+void
+rebuild_frequencies (void)
+{
+  timevar_push (TV_REBUILD_FREQUENCIES);
+
+  /* When the max bb count in the function is small, there is a higher
+     chance that there were truncation errors in the integer scaling
+     of counts by inlining and other optimizations. This could lead
+     to incorrect classification of code as being cold when it isn't.
+     In that case, force the estimation of bb counts/frequencies from the
+     branch probabilities, rather than computing frequencies from counts,
+     which may also lead to frequencies incorrectly reduced to 0. There
+     is less precision in the probabilities, so we only do this for small
+     max counts.  */
+  gcov_type count_max = 0;
+  basic_block bb;
+  FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
+    count_max = MAX (bb->count, count_max);
+
+  if (profile_status_for_fn (cfun) == PROFILE_GUESSED
+      || (profile_status_for_fn (cfun) == PROFILE_READ && count_max < REG_BR_PROB_BASE/10))
+    {
+      loop_optimizer_init (0);
+      add_noreturn_fake_exit_edges ();
+      mark_irreducible_loops ();
+      connect_infinite_loops_to_exit ();
+      estimate_bb_frequencies (true);
+      remove_fake_exit_edges ();
+      loop_optimizer_finalize ();
+    }
+  else if (profile_status_for_fn (cfun) == PROFILE_READ)
+    counts_to_freqs ();
+  else
+    gcc_unreachable ();
+  timevar_pop (TV_REBUILD_FREQUENCIES);
+}