--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/cfgloop.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,1637 @@
+/* Natural loop discovery code for GNU compiler.
+   Copyright (C) 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008
+   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/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "rtl.h"
+#include "hard-reg-set.h"
+#include "obstack.h"
+#include "function.h"
+#include "basic-block.h"
+#include "toplev.h"
+#include "cfgloop.h"
+#include "flags.h"
+#include "tree.h"
+#include "tree-flow.h"
+#include "pointer-set.h"
+#include "output.h"
+#include "ggc.h"
+
+static void flow_loops_cfg_dump (FILE *);
+
+/* Dump loop related CFG information.  */
+
+static void
+flow_loops_cfg_dump (FILE *file)
+{
+  basic_block bb;
+
+  if (!file)
+    return;
+
+  FOR_EACH_BB (bb)
+    {
+      edge succ;
+      edge_iterator ei;
+
+      fprintf (file, ";; %d succs { ", bb->index);
+      FOR_EACH_EDGE (succ, ei, bb->succs)
+	fprintf (file, "%d ", succ->dest->index);
+      fprintf (file, "}\n");
+    }
+}
+
+/* Return nonzero if the nodes of LOOP are a subset of OUTER.  */
+
+bool
+flow_loop_nested_p (const struct loop *outer, const struct loop *loop)
+{
+  unsigned odepth = loop_depth (outer);
+
+  return (loop_depth (loop) > odepth
+	  && VEC_index (loop_p, loop->superloops, odepth) == outer);
+}
+
+/* Returns the loop such that LOOP is nested DEPTH (indexed from zero)
+   loops within LOOP.  */
+
+struct loop *
+superloop_at_depth (struct loop *loop, unsigned depth)
+{
+  unsigned ldepth = loop_depth (loop);
+
+  gcc_assert (depth <= ldepth);
+
+  if (depth == ldepth)
+    return loop;
+
+  return VEC_index (loop_p, loop->superloops, depth);
+}
+
+/* Returns the list of the latch edges of LOOP.  */
+
+static VEC (edge, heap) *
+get_loop_latch_edges (const struct loop *loop)
+{
+  edge_iterator ei;
+  edge e;
+  VEC (edge, heap) *ret = NULL;
+
+  FOR_EACH_EDGE (e, ei, loop->header->preds)
+    {
+      if (dominated_by_p (CDI_DOMINATORS, e->src, loop->header))
+	VEC_safe_push (edge, heap, ret, e);
+    }
+
+  return ret;
+}
+
+/* Dump the loop information specified by LOOP to the stream FILE
+   using auxiliary dump callback function LOOP_DUMP_AUX if non null.  */
+
+void
+flow_loop_dump (const struct loop *loop, FILE *file,
+		void (*loop_dump_aux) (const struct loop *, FILE *, int),
+		int verbose)
+{
+  basic_block *bbs;
+  unsigned i;
+  VEC (edge, heap) *latches;
+  edge e;
+
+  if (! loop || ! loop->header)
+    return;
+
+  fprintf (file, ";;\n;; Loop %d\n", loop->num);
+
+  fprintf (file, ";;  header %d, ", loop->header->index);
+  if (loop->latch)
+    fprintf (file, "latch %d\n", loop->latch->index);
+  else
+    {
+      fprintf (file, "multiple latches:");
+      latches = get_loop_latch_edges (loop);
+      for (i = 0; VEC_iterate (edge, latches, i, e); i++)
+	fprintf (file, " %d", e->src->index);
+      VEC_free (edge, heap, latches);
+      fprintf (file, "\n");
+    }
+
+  fprintf (file, ";;  depth %d, outer %ld\n",
+	   loop_depth (loop), (long) (loop_outer (loop)
+				      ? loop_outer (loop)->num : -1));
+
+  fprintf (file, ";;  nodes:");
+  bbs = get_loop_body (loop);
+  for (i = 0; i < loop->num_nodes; i++)
+    fprintf (file, " %d", bbs[i]->index);
+  free (bbs);
+  fprintf (file, "\n");
+
+  if (loop_dump_aux)
+    loop_dump_aux (loop, file, verbose);
+}
+
+/* Dump the loop information about loops to the stream FILE,
+   using auxiliary dump callback function LOOP_DUMP_AUX if non null.  */
+
+void
+flow_loops_dump (FILE *file, void (*loop_dump_aux) (const struct loop *, FILE *, int), int verbose)
+{
+  loop_iterator li;
+  struct loop *loop;
+
+  if (!current_loops || ! file)
+    return;
+
+  fprintf (file, ";; %d loops found\n", number_of_loops ());
+
+  FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT)
+    {
+      flow_loop_dump (loop, file, loop_dump_aux, verbose);
+    }
+
+  if (verbose)
+    flow_loops_cfg_dump (file);
+}
+
+/* Free data allocated for LOOP.  */
+
+void
+flow_loop_free (struct loop *loop)
+{
+  struct loop_exit *exit, *next;
+
+  VEC_free (loop_p, gc, loop->superloops);
+
+  /* Break the list of the loop exit records.  They will be freed when the
+     corresponding edge is rescanned or removed, and this avoids
+     accessing the (already released) head of the list stored in the
+     loop structure.  */
+  for (exit = loop->exits->next; exit != loop->exits; exit = next)
+    {
+      next = exit->next;
+      exit->next = exit;
+      exit->prev = exit;
+    }
+
+  ggc_free (loop->exits);
+  ggc_free (loop);
+}
+
+/* Free all the memory allocated for LOOPS.  */
+
+void
+flow_loops_free (struct loops *loops)
+{
+  if (loops->larray)
+    {
+      unsigned i;
+      loop_p loop;
+
+      /* Free the loop descriptors.  */
+      for (i = 0; VEC_iterate (loop_p, loops->larray, i, loop); i++)
+	{
+	  if (!loop)
+	    continue;
+
+	  flow_loop_free (loop);
+	}
+
+      VEC_free (loop_p, gc, loops->larray);
+    }
+}
+
+/* Find the nodes contained within the LOOP with header HEADER.
+   Return the number of nodes within the loop.  */
+
+int
+flow_loop_nodes_find (basic_block header, struct loop *loop)
+{
+  VEC (basic_block, heap) *stack = NULL;
+  int num_nodes = 1;
+  edge latch;
+  edge_iterator latch_ei;
+  unsigned depth = loop_depth (loop);
+
+  header->loop_father = loop;
+  header->loop_depth = depth;
+
+  FOR_EACH_EDGE (latch, latch_ei, loop->header->preds)
+    {
+      if (latch->src->loop_father == loop
+	  || !dominated_by_p (CDI_DOMINATORS, latch->src, loop->header))
+	continue;
+
+      num_nodes++;
+      VEC_safe_push (basic_block, heap, stack, latch->src);
+      latch->src->loop_father = loop;
+      latch->src->loop_depth = depth;
+
+      while (!VEC_empty (basic_block, stack))
+	{
+	  basic_block node;
+	  edge e;
+	  edge_iterator ei;
+
+	  node = VEC_pop (basic_block, stack);
+
+	  FOR_EACH_EDGE (e, ei, node->preds)
+	    {
+	      basic_block ancestor = e->src;
+
+	      if (ancestor->loop_father != loop)
+		{
+		  ancestor->loop_father = loop;
+		  ancestor->loop_depth = depth;
+		  num_nodes++;
+		  VEC_safe_push (basic_block, heap, stack, ancestor);
+		}
+	    }
+	}
+    }
+  VEC_free (basic_block, heap, stack);
+
+  return num_nodes;
+}
+
+/* Records the vector of superloops of the loop LOOP, whose immediate
+   superloop is FATHER.  */
+
+static void
+establish_preds (struct loop *loop, struct loop *father)
+{
+  loop_p ploop;
+  unsigned depth = loop_depth (father) + 1;
+  unsigned i;
+
+  VEC_truncate (loop_p, loop->superloops, 0);
+  VEC_reserve (loop_p, gc, loop->superloops, depth);
+  for (i = 0; VEC_iterate (loop_p, father->superloops, i, ploop); i++)
+    VEC_quick_push (loop_p, loop->superloops, ploop);
+  VEC_quick_push (loop_p, loop->superloops, father);
+
+  for (ploop = loop->inner; ploop; ploop = ploop->next)
+    establish_preds (ploop, loop);
+}
+
+/* Add LOOP to the loop hierarchy tree where FATHER is father of the
+   added loop.  If LOOP has some children, take care of that their
+   pred field will be initialized correctly.  */
+
+void
+flow_loop_tree_node_add (struct loop *father, struct loop *loop)
+{
+  loop->next = father->inner;
+  father->inner = loop;
+
+  establish_preds (loop, father);
+}
+
+/* Remove LOOP from the loop hierarchy tree.  */
+
+void
+flow_loop_tree_node_remove (struct loop *loop)
+{
+  struct loop *prev, *father;
+
+  father = loop_outer (loop);
+
+  /* Remove loop from the list of sons.  */
+  if (father->inner == loop)
+    father->inner = loop->next;
+  else
+    {
+      for (prev = father->inner; prev->next != loop; prev = prev->next)
+	continue;
+      prev->next = loop->next;
+    }
+
+  VEC_truncate (loop_p, loop->superloops, 0);
+}
+
+/* Allocates and returns new loop structure.  */
+
+struct loop *
+alloc_loop (void)
+{
+  struct loop *loop = GGC_CNEW (struct loop);
+
+  loop->exits = GGC_CNEW (struct loop_exit);
+  loop->exits->next = loop->exits->prev = loop->exits;
+
+  return loop;
+}
+
+/* Initializes loops structure LOOPS, reserving place for NUM_LOOPS loops
+   (including the root of the loop tree).  */
+
+static void
+init_loops_structure (struct loops *loops, unsigned num_loops)
+{
+  struct loop *root;
+
+  memset (loops, 0, sizeof *loops);
+  loops->larray = VEC_alloc (loop_p, gc, num_loops);
+
+  /* Dummy loop containing whole function.  */
+  root = alloc_loop ();
+  root->num_nodes = n_basic_blocks;
+  root->latch = EXIT_BLOCK_PTR;
+  root->header = ENTRY_BLOCK_PTR;
+  ENTRY_BLOCK_PTR->loop_father = root;
+  EXIT_BLOCK_PTR->loop_father = root;
+
+  VEC_quick_push (loop_p, loops->larray, root);
+  loops->tree_root = root;
+}
+
+/* Find all the natural loops in the function and save in LOOPS structure and
+   recalculate loop_depth information in basic block structures.
+   Return the number of natural loops found.  */
+
+int
+flow_loops_find (struct loops *loops)
+{
+  int b;
+  int num_loops;
+  edge e;
+  sbitmap headers;
+  int *dfs_order;
+  int *rc_order;
+  basic_block header;
+  basic_block bb;
+
+  /* Ensure that the dominators are computed.  */
+  calculate_dominance_info (CDI_DOMINATORS);
+
+  /* Taking care of this degenerate case makes the rest of
+     this code simpler.  */
+  if (n_basic_blocks == NUM_FIXED_BLOCKS)
+    {
+      init_loops_structure (loops, 1);
+      return 1;
+    }
+
+  dfs_order = NULL;
+  rc_order = NULL;
+
+  /* Count the number of loop headers.  This should be the
+     same as the number of natural loops.  */
+  headers = sbitmap_alloc (last_basic_block);
+  sbitmap_zero (headers);
+
+  num_loops = 0;
+  FOR_EACH_BB (header)
+    {
+      edge_iterator ei;
+
+      header->loop_depth = 0;
+
+      /* If we have an abnormal predecessor, do not consider the
+	 loop (not worth the problems).  */
+      FOR_EACH_EDGE (e, ei, header->preds)
+	if (e->flags & EDGE_ABNORMAL)
+	  break;
+      if (e)
+	continue;
+
+      FOR_EACH_EDGE (e, ei, header->preds)
+	{
+	  basic_block latch = e->src;
+
+	  gcc_assert (!(e->flags & EDGE_ABNORMAL));
+
+	  /* Look for back edges where a predecessor is dominated
+	     by this block.  A natural loop has a single entry
+	     node (header) that dominates all the nodes in the
+	     loop.  It also has single back edge to the header
+	     from a latch node.  */
+	  if (latch != ENTRY_BLOCK_PTR
+	      && dominated_by_p (CDI_DOMINATORS, latch, header))
+	    {
+	      /* Shared headers should be eliminated by now.  */
+	      SET_BIT (headers, header->index);
+	      num_loops++;
+	    }
+	}
+    }
+
+  /* Allocate loop structures.  */
+  init_loops_structure (loops, num_loops + 1);
+
+  /* Find and record information about all the natural loops
+     in the CFG.  */
+  FOR_EACH_BB (bb)
+    bb->loop_father = loops->tree_root;
+
+  if (num_loops)
+    {
+      /* Compute depth first search order of the CFG so that outer
+	 natural loops will be found before inner natural loops.  */
+      dfs_order = XNEWVEC (int, n_basic_blocks);
+      rc_order = XNEWVEC (int, n_basic_blocks);
+      pre_and_rev_post_order_compute (dfs_order, rc_order, false);
+
+      num_loops = 1;
+
+      for (b = 0; b < n_basic_blocks - NUM_FIXED_BLOCKS; b++)
+	{
+	  struct loop *loop;
+	  edge_iterator ei;
+
+	  /* Search the nodes of the CFG in reverse completion order
+	     so that we can find outer loops first.  */
+	  if (!TEST_BIT (headers, rc_order[b]))
+	    continue;
+
+	  header = BASIC_BLOCK (rc_order[b]);
+
+	  loop = alloc_loop ();
+	  VEC_quick_push (loop_p, loops->larray, loop);
+
+	  loop->header = header;
+	  loop->num = num_loops;
+	  num_loops++;
+
+	  flow_loop_tree_node_add (header->loop_father, loop);
+	  loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
+
+	  /* Look for the latch for this header block, if it has just a
+	     single one.  */
+	  FOR_EACH_EDGE (e, ei, header->preds)
+	    {
+	      basic_block latch = e->src;
+
+	      if (flow_bb_inside_loop_p (loop, latch))
+		{
+		  if (loop->latch != NULL)
+		    {
+		      /* More than one latch edge.  */
+		      loop->latch = NULL;
+		      break;
+		    }
+		  loop->latch = latch;
+		}
+	    }
+	}
+
+      free (dfs_order);
+      free (rc_order);
+    }
+
+  sbitmap_free (headers);
+
+  loops->exits = NULL;
+  return VEC_length (loop_p, loops->larray);
+}
+
+/* Ratio of frequencies of edges so that one of more latch edges is
+   considered to belong to inner loop with same header.  */
+#define HEAVY_EDGE_RATIO 8
+
+/* Minimum number of samples for that we apply
+   find_subloop_latch_edge_by_profile heuristics.  */
+#define HEAVY_EDGE_MIN_SAMPLES 10
+
+/* If the profile info is available, finds an edge in LATCHES that much more
+   frequent than the remaining edges.  Returns such an edge, or NULL if we do
+   not find one.
+
+   We do not use guessed profile here, only the measured one.  The guessed
+   profile is usually too flat and unreliable for this (and it is mostly based
+   on the loop structure of the program, so it does not make much sense to
+   derive the loop structure from it).  */
+   
+static edge
+find_subloop_latch_edge_by_profile (VEC (edge, heap) *latches)
+{
+  unsigned i;
+  edge e, me = NULL;
+  gcov_type mcount = 0, tcount = 0;
+
+  for (i = 0; VEC_iterate (edge, latches, i, e); i++)
+    {
+      if (e->count > mcount)
+	{
+	  me = e;
+	  mcount = e->count;
+	}
+      tcount += e->count;
+    }
+
+  if (tcount < HEAVY_EDGE_MIN_SAMPLES
+      || (tcount - mcount) * HEAVY_EDGE_RATIO > tcount)
+    return NULL;
+
+  if (dump_file)
+    fprintf (dump_file,
+	     "Found latch edge %d -> %d using profile information.\n",
+	     me->src->index, me->dest->index);
+  return me;
+}
+
+/* Among LATCHES, guesses a latch edge of LOOP corresponding to subloop, based
+   on the structure of induction variables.  Returns this edge, or NULL if we
+   do not find any.
+
+   We are quite conservative, and look just for an obvious simple innermost
+   loop (which is the case where we would lose the most performance by not
+   disambiguating the loop).  More precisely, we look for the following
+   situation: The source of the chosen latch edge dominates sources of all
+   the other latch edges.  Additionally, the header does not contain a phi node
+   such that the argument from the chosen edge is equal to the argument from
+   another edge.  */
+
+static edge
+find_subloop_latch_edge_by_ivs (struct loop *loop ATTRIBUTE_UNUSED, VEC (edge, heap) *latches)
+{
+  edge e, latch = VEC_index (edge, latches, 0);
+  unsigned i;
+  gimple phi;
+  gimple_stmt_iterator psi;
+  tree lop;
+  basic_block bb;
+
+  /* Find the candidate for the latch edge.  */
+  for (i = 1; VEC_iterate (edge, latches, i, e); i++)
+    if (dominated_by_p (CDI_DOMINATORS, latch->src, e->src))
+      latch = e;
+
+  /* Verify that it dominates all the latch edges.  */
+  for (i = 0; VEC_iterate (edge, latches, i, e); i++)
+    if (!dominated_by_p (CDI_DOMINATORS, e->src, latch->src))
+      return NULL;
+
+  /* Check for a phi node that would deny that this is a latch edge of
+     a subloop.  */
+  for (psi = gsi_start_phis (loop->header); !gsi_end_p (psi); gsi_next (&psi))
+    {
+      phi = gsi_stmt (psi);
+      lop = PHI_ARG_DEF_FROM_EDGE (phi, latch);
+
+      /* Ignore the values that are not changed inside the subloop.  */
+      if (TREE_CODE (lop) != SSA_NAME
+	  || SSA_NAME_DEF_STMT (lop) == phi)
+	continue;
+      bb = gimple_bb (SSA_NAME_DEF_STMT (lop));
+      if (!bb || !flow_bb_inside_loop_p (loop, bb))
+	continue;
+
+      for (i = 0; VEC_iterate (edge, latches, i, e); i++)
+	if (e != latch
+	    && PHI_ARG_DEF_FROM_EDGE (phi, e) == lop)
+	  return NULL;
+    }
+
+  if (dump_file)
+    fprintf (dump_file,
+	     "Found latch edge %d -> %d using iv structure.\n",
+	     latch->src->index, latch->dest->index);
+  return latch;
+}
+
+/* If we can determine that one of the several latch edges of LOOP behaves
+   as a latch edge of a separate subloop, returns this edge.  Otherwise
+   returns NULL.  */
+
+static edge
+find_subloop_latch_edge (struct loop *loop)
+{
+  VEC (edge, heap) *latches = get_loop_latch_edges (loop);
+  edge latch = NULL;
+
+  if (VEC_length (edge, latches) > 1)
+    {
+      latch = find_subloop_latch_edge_by_profile (latches);
+
+      if (!latch
+	  /* We consider ivs to guess the latch edge only in SSA.  Perhaps we
+	     should use cfghook for this, but it is hard to imagine it would
+	     be useful elsewhere.  */
+	  && current_ir_type () == IR_GIMPLE)
+	latch = find_subloop_latch_edge_by_ivs (loop, latches);
+    }
+
+  VEC_free (edge, heap, latches);
+  return latch;
+}
+
+/* Callback for make_forwarder_block.  Returns true if the edge E is marked
+   in the set MFB_REIS_SET.  */
+
+static struct pointer_set_t *mfb_reis_set;
+static bool
+mfb_redirect_edges_in_set (edge e)
+{
+  return pointer_set_contains (mfb_reis_set, e);
+}
+
+/* Creates a subloop of LOOP with latch edge LATCH.  */
+
+static void
+form_subloop (struct loop *loop, edge latch)
+{
+  edge_iterator ei;
+  edge e, new_entry;
+  struct loop *new_loop;
+      
+  mfb_reis_set = pointer_set_create ();
+  FOR_EACH_EDGE (e, ei, loop->header->preds)
+    {
+      if (e != latch)
+	pointer_set_insert (mfb_reis_set, e);
+    }
+  new_entry = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
+				    NULL);
+  pointer_set_destroy (mfb_reis_set);
+
+  loop->header = new_entry->src;
+
+  /* Find the blocks and subloops that belong to the new loop, and add it to
+     the appropriate place in the loop tree.  */
+  new_loop = alloc_loop ();
+  new_loop->header = new_entry->dest;
+  new_loop->latch = latch->src;
+  add_loop (new_loop, loop);
+}
+
+/* Make all the latch edges of LOOP to go to a single forwarder block --
+   a new latch of LOOP.  */
+
+static void
+merge_latch_edges (struct loop *loop)
+{
+  VEC (edge, heap) *latches = get_loop_latch_edges (loop);
+  edge latch, e;
+  unsigned i;
+
+  gcc_assert (VEC_length (edge, latches) > 0);
+
+  if (VEC_length (edge, latches) == 1)
+    loop->latch = VEC_index (edge, latches, 0)->src;
+  else
+    {
+      if (dump_file)
+	fprintf (dump_file, "Merged latch edges of loop %d\n", loop->num);
+
+      mfb_reis_set = pointer_set_create ();
+      for (i = 0; VEC_iterate (edge, latches, i, e); i++)
+	pointer_set_insert (mfb_reis_set, e);
+      latch = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
+				    NULL);
+      pointer_set_destroy (mfb_reis_set);
+
+      loop->header = latch->dest;
+      loop->latch = latch->src;
+    }
+
+  VEC_free (edge, heap, latches);
+}
+
+/* LOOP may have several latch edges.  Transform it into (possibly several)
+   loops with single latch edge.  */
+
+static void
+disambiguate_multiple_latches (struct loop *loop)
+{
+  edge e;
+
+  /* We eliminate the multiple latches by splitting the header to the forwarder
+     block F and the rest R, and redirecting the edges.  There are two cases:
+
+     1) If there is a latch edge E that corresponds to a subloop (we guess
+        that based on profile -- if it is taken much more often than the
+	remaining edges; and on trees, using the information about induction
+	variables of the loops), we redirect E to R, all the remaining edges to
+	F, then rescan the loops and try again for the outer loop.
+     2) If there is no such edge, we redirect all latch edges to F, and the
+        entry edges to R, thus making F the single latch of the loop.  */
+
+  if (dump_file)
+    fprintf (dump_file, "Disambiguating loop %d with multiple latches\n",
+	     loop->num);
+
+  /* During latch merging, we may need to redirect the entry edges to a new
+     block.  This would cause problems if the entry edge was the one from the
+     entry block.  To avoid having to handle this case specially, split
+     such entry edge.  */
+  e = find_edge (ENTRY_BLOCK_PTR, loop->header);
+  if (e)
+    split_edge (e);
+
+  while (1)
+    {
+      e = find_subloop_latch_edge (loop);
+      if (!e)
+	break;
+
+      form_subloop (loop, e);
+    }
+
+  merge_latch_edges (loop);
+}
+
+/* Split loops with multiple latch edges.  */
+
+void
+disambiguate_loops_with_multiple_latches (void)
+{
+  loop_iterator li;
+  struct loop *loop;
+
+  FOR_EACH_LOOP (li, loop, 0)
+    {
+      if (!loop->latch)
+	disambiguate_multiple_latches (loop);
+    }
+}
+
+/* Return nonzero if basic block BB belongs to LOOP.  */
+bool
+flow_bb_inside_loop_p (const struct loop *loop, const_basic_block bb)
+{
+  struct loop *source_loop;
+
+  if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR)
+    return 0;
+
+  source_loop = bb->loop_father;
+  return loop == source_loop || flow_loop_nested_p (loop, source_loop);
+}
+
+/* Enumeration predicate for get_loop_body_with_size.  */
+static bool
+glb_enum_p (const_basic_block bb, const void *glb_loop)
+{
+  const struct loop *const loop = (const struct loop *) glb_loop;
+  return (bb != loop->header
+	  && dominated_by_p (CDI_DOMINATORS, bb, loop->header));
+}
+
+/* Gets basic blocks of a LOOP.  Header is the 0-th block, rest is in dfs
+   order against direction of edges from latch.  Specially, if
+   header != latch, latch is the 1-st block.  LOOP cannot be the fake
+   loop tree root, and its size must be at most MAX_SIZE.  The blocks
+   in the LOOP body are stored to BODY, and the size of the LOOP is
+   returned.  */
+
+unsigned
+get_loop_body_with_size (const struct loop *loop, basic_block *body,
+			 unsigned max_size)
+{
+  return dfs_enumerate_from (loop->header, 1, glb_enum_p,
+			     body, max_size, loop);
+}
+
+/* Gets basic blocks of a LOOP.  Header is the 0-th block, rest is in dfs
+   order against direction of edges from latch.  Specially, if
+   header != latch, latch is the 1-st block.  */
+
+basic_block *
+get_loop_body (const struct loop *loop)
+{
+  basic_block *body, bb;
+  unsigned tv = 0;
+
+  gcc_assert (loop->num_nodes);
+
+  body = XCNEWVEC (basic_block, loop->num_nodes);
+
+  if (loop->latch == EXIT_BLOCK_PTR)
+    {
+      /* There may be blocks unreachable from EXIT_BLOCK, hence we need to
+	 special-case the fake loop that contains the whole function.  */
+      gcc_assert (loop->num_nodes == (unsigned) n_basic_blocks);
+      body[tv++] = loop->header;
+      body[tv++] = EXIT_BLOCK_PTR;
+      FOR_EACH_BB (bb)
+	body[tv++] = bb;
+    }
+  else
+    tv = get_loop_body_with_size (loop, body, loop->num_nodes);
+
+  gcc_assert (tv == loop->num_nodes);
+  return body;
+}
+
+/* Fills dominance descendants inside LOOP of the basic block BB into
+   array TOVISIT from index *TV.  */
+
+static void
+fill_sons_in_loop (const struct loop *loop, basic_block bb,
+		   basic_block *tovisit, int *tv)
+{
+  basic_block son, postpone = NULL;
+
+  tovisit[(*tv)++] = bb;
+  for (son = first_dom_son (CDI_DOMINATORS, bb);
+       son;
+       son = next_dom_son (CDI_DOMINATORS, son))
+    {
+      if (!flow_bb_inside_loop_p (loop, son))
+	continue;
+
+      if (dominated_by_p (CDI_DOMINATORS, loop->latch, son))
+	{
+	  postpone = son;
+	  continue;
+	}
+      fill_sons_in_loop (loop, son, tovisit, tv);
+    }
+
+  if (postpone)
+    fill_sons_in_loop (loop, postpone, tovisit, tv);
+}
+
+/* Gets body of a LOOP (that must be different from the outermost loop)
+   sorted by dominance relation.  Additionally, if a basic block s dominates
+   the latch, then only blocks dominated by s are be after it.  */
+
+basic_block *
+get_loop_body_in_dom_order (const struct loop *loop)
+{
+  basic_block *tovisit;
+  int tv;
+
+  gcc_assert (loop->num_nodes);
+
+  tovisit = XCNEWVEC (basic_block, loop->num_nodes);
+
+  gcc_assert (loop->latch != EXIT_BLOCK_PTR);
+
+  tv = 0;
+  fill_sons_in_loop (loop, loop->header, tovisit, &tv);
+
+  gcc_assert (tv == (int) loop->num_nodes);
+
+  return tovisit;
+}
+
+/* Gets body of a LOOP sorted via provided BB_COMPARATOR.  */
+
+basic_block *
+get_loop_body_in_custom_order (const struct loop *loop, 
+			       int (*bb_comparator) (const void *, const void *))
+{
+  basic_block *bbs = get_loop_body (loop);
+
+  qsort (bbs, loop->num_nodes, sizeof (basic_block), bb_comparator);
+
+  return bbs;
+}
+
+/* Get body of a LOOP in breadth first sort order.  */
+
+basic_block *
+get_loop_body_in_bfs_order (const struct loop *loop)
+{
+  basic_block *blocks;
+  basic_block bb;
+  bitmap visited;
+  unsigned int i = 0;
+  unsigned int vc = 1;
+
+  gcc_assert (loop->num_nodes);
+  gcc_assert (loop->latch != EXIT_BLOCK_PTR);
+
+  blocks = XCNEWVEC (basic_block, loop->num_nodes);
+  visited = BITMAP_ALLOC (NULL);
+
+  bb = loop->header;
+  while (i < loop->num_nodes)
+    {
+      edge e;
+      edge_iterator ei;
+
+      if (!bitmap_bit_p (visited, bb->index))
+	{
+	  /* This basic block is now visited */
+	  bitmap_set_bit (visited, bb->index);
+	  blocks[i++] = bb;
+	}
+
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	{
+	  if (flow_bb_inside_loop_p (loop, e->dest))
+	    {
+	      if (!bitmap_bit_p (visited, e->dest->index))
+		{
+		  bitmap_set_bit (visited, e->dest->index);
+		  blocks[i++] = e->dest;
+		}
+	    }
+	}
+
+      gcc_assert (i >= vc);
+
+      bb = blocks[vc++];
+    }
+
+  BITMAP_FREE (visited);
+  return blocks;
+}
+
+/* Hash function for struct loop_exit.  */
+
+static hashval_t
+loop_exit_hash (const void *ex)
+{
+  const struct loop_exit *const exit = (const struct loop_exit *) ex;
+
+  return htab_hash_pointer (exit->e);
+}
+
+/* Equality function for struct loop_exit.  Compares with edge.  */
+
+static int
+loop_exit_eq (const void *ex, const void *e)
+{
+  const struct loop_exit *const exit = (const struct loop_exit *) ex;
+
+  return exit->e == e;
+}
+
+/* Frees the list of loop exit descriptions EX.  */
+
+static void
+loop_exit_free (void *ex)
+{
+  struct loop_exit *exit = (struct loop_exit *) ex, *next;
+
+  for (; exit; exit = next)
+    {
+      next = exit->next_e;
+	  
+      exit->next->prev = exit->prev;
+      exit->prev->next = exit->next;
+
+      ggc_free (exit);
+    }
+}
+
+/* Returns the list of records for E as an exit of a loop.  */
+
+static struct loop_exit *
+get_exit_descriptions (edge e)
+{
+  return (struct loop_exit *) htab_find_with_hash (current_loops->exits, e,
+			                           htab_hash_pointer (e));
+}
+
+/* Updates the lists of loop exits in that E appears.
+   If REMOVED is true, E is being removed, and we
+   just remove it from the lists of exits.
+   If NEW_EDGE is true and E is not a loop exit, we
+   do not try to remove it from loop exit lists.  */
+
+void
+rescan_loop_exit (edge e, bool new_edge, bool removed)
+{
+  void **slot;
+  struct loop_exit *exits = NULL, *exit;
+  struct loop *aloop, *cloop;
+
+  if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
+    return;
+
+  if (!removed
+      && e->src->loop_father != NULL
+      && e->dest->loop_father != NULL
+      && !flow_bb_inside_loop_p (e->src->loop_father, e->dest))
+    {
+      cloop = find_common_loop (e->src->loop_father, e->dest->loop_father);
+      for (aloop = e->src->loop_father;
+	   aloop != cloop;
+	   aloop = loop_outer (aloop))
+	{
+	  exit = GGC_NEW (struct loop_exit);
+	  exit->e = e;
+
+	  exit->next = aloop->exits->next;
+	  exit->prev = aloop->exits;
+	  exit->next->prev = exit;
+	  exit->prev->next = exit;
+
+	  exit->next_e = exits;
+	  exits = exit;
+	}
+    } 
+
+  if (!exits && new_edge)
+    return;
+
+  slot = htab_find_slot_with_hash (current_loops->exits, e,
+				   htab_hash_pointer (e),
+				   exits ? INSERT : NO_INSERT);
+  if (!slot)
+    return;
+
+  if (exits)
+    {
+      if (*slot)
+	loop_exit_free (*slot);
+      *slot = exits;
+    }
+  else
+    htab_clear_slot (current_loops->exits, slot);
+}
+
+/* For each loop, record list of exit edges, and start maintaining these
+   lists.  */
+
+void
+record_loop_exits (void)
+{
+  basic_block bb;
+  edge_iterator ei;
+  edge e;
+
+  if (!current_loops)
+    return;
+
+  if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
+    return;
+  loops_state_set (LOOPS_HAVE_RECORDED_EXITS);
+
+  gcc_assert (current_loops->exits == NULL);
+  current_loops->exits = htab_create_alloc (2 * number_of_loops (),
+					    loop_exit_hash,
+					    loop_exit_eq,
+					    loop_exit_free,
+					    ggc_calloc, ggc_free);
+
+  FOR_EACH_BB (bb)
+    {
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	{
+	  rescan_loop_exit (e, true, false);
+	}
+    }
+}
+
+/* Dumps information about the exit in *SLOT to FILE.
+   Callback for htab_traverse.  */
+
+static int
+dump_recorded_exit (void **slot, void *file)
+{
+  struct loop_exit *exit = (struct loop_exit *) *slot;
+  unsigned n = 0;
+  edge e = exit->e;
+
+  for (; exit != NULL; exit = exit->next_e)
+    n++;
+
+  fprintf ((FILE*) file, "Edge %d->%d exits %u loops\n",
+	   e->src->index, e->dest->index, n);
+
+  return 1;
+}
+
+/* Dumps the recorded exits of loops to FILE.  */
+
+extern void dump_recorded_exits (FILE *);
+void
+dump_recorded_exits (FILE *file)
+{
+  if (!current_loops->exits)
+    return;
+  htab_traverse (current_loops->exits, dump_recorded_exit, file);
+}
+
+/* Releases lists of loop exits.  */
+
+void
+release_recorded_exits (void)
+{
+  gcc_assert (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS));
+  htab_delete (current_loops->exits);
+  current_loops->exits = NULL;
+  loops_state_clear (LOOPS_HAVE_RECORDED_EXITS);
+}
+
+/* Returns the list of the exit edges of a LOOP.  */
+
+VEC (edge, heap) *
+get_loop_exit_edges (const struct loop *loop)
+{
+  VEC (edge, heap) *edges = NULL;
+  edge e;
+  unsigned i;
+  basic_block *body;
+  edge_iterator ei;
+  struct loop_exit *exit;
+
+  gcc_assert (loop->latch != EXIT_BLOCK_PTR);
+
+  /* If we maintain the lists of exits, use them.  Otherwise we must
+     scan the body of the loop.  */
+  if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
+    {
+      for (exit = loop->exits->next; exit->e; exit = exit->next)
+	VEC_safe_push (edge, heap, edges, exit->e);
+    }
+  else
+    {
+      body = get_loop_body (loop);
+      for (i = 0; i < loop->num_nodes; i++)
+	FOR_EACH_EDGE (e, ei, body[i]->succs)
+	  {
+	    if (!flow_bb_inside_loop_p (loop, e->dest))
+	      VEC_safe_push (edge, heap, edges, e);
+	  }
+      free (body);
+    }
+
+  return edges;
+}
+
+/* Counts the number of conditional branches inside LOOP.  */
+
+unsigned
+num_loop_branches (const struct loop *loop)
+{
+  unsigned i, n;
+  basic_block * body;
+
+  gcc_assert (loop->latch != EXIT_BLOCK_PTR);
+
+  body = get_loop_body (loop);
+  n = 0;
+  for (i = 0; i < loop->num_nodes; i++)
+    if (EDGE_COUNT (body[i]->succs) >= 2)
+      n++;
+  free (body);
+
+  return n;
+}
+
+/* Adds basic block BB to LOOP.  */
+void
+add_bb_to_loop (basic_block bb, struct loop *loop)
+{
+  unsigned i;
+  loop_p ploop;
+  edge_iterator ei;
+  edge e;
+
+  gcc_assert (bb->loop_father == NULL);
+  bb->loop_father = loop;
+  bb->loop_depth = loop_depth (loop);
+  loop->num_nodes++;
+  for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++)
+    ploop->num_nodes++;
+
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    {
+      rescan_loop_exit (e, true, false);
+    }
+  FOR_EACH_EDGE (e, ei, bb->preds)
+    {
+      rescan_loop_exit (e, true, false);
+    }
+}
+
+/* Remove basic block BB from loops.  */
+void
+remove_bb_from_loops (basic_block bb)
+{
+  int i;
+  struct loop *loop = bb->loop_father;
+  loop_p ploop;
+  edge_iterator ei;
+  edge e;
+
+  gcc_assert (loop != NULL);
+  loop->num_nodes--;
+  for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++)
+    ploop->num_nodes--;
+  bb->loop_father = NULL;
+  bb->loop_depth = 0;
+
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    {
+      rescan_loop_exit (e, false, true);
+    }
+  FOR_EACH_EDGE (e, ei, bb->preds)
+    {
+      rescan_loop_exit (e, false, true);
+    }
+}
+
+/* Finds nearest common ancestor in loop tree for given loops.  */
+struct loop *
+find_common_loop (struct loop *loop_s, struct loop *loop_d)
+{
+  unsigned sdepth, ddepth;
+
+  if (!loop_s) return loop_d;
+  if (!loop_d) return loop_s;
+
+  sdepth = loop_depth (loop_s);
+  ddepth = loop_depth (loop_d);
+
+  if (sdepth < ddepth)
+    loop_d = VEC_index (loop_p, loop_d->superloops, sdepth);
+  else if (sdepth > ddepth)
+    loop_s = VEC_index (loop_p, loop_s->superloops, ddepth);
+
+  while (loop_s != loop_d)
+    {
+      loop_s = loop_outer (loop_s);
+      loop_d = loop_outer (loop_d);
+    }
+  return loop_s;
+}
+
+/* Removes LOOP from structures and frees its data.  */
+
+void
+delete_loop (struct loop *loop)
+{
+  /* Remove the loop from structure.  */
+  flow_loop_tree_node_remove (loop);
+
+  /* Remove loop from loops array.  */
+  VEC_replace (loop_p, current_loops->larray, loop->num, NULL);
+
+  /* Free loop data.  */
+  flow_loop_free (loop);
+}
+
+/* Cancels the LOOP; it must be innermost one.  */
+
+static void
+cancel_loop (struct loop *loop)
+{
+  basic_block *bbs;
+  unsigned i;
+  struct loop *outer = loop_outer (loop);
+
+  gcc_assert (!loop->inner);
+
+  /* Move blocks up one level (they should be removed as soon as possible).  */
+  bbs = get_loop_body (loop);
+  for (i = 0; i < loop->num_nodes; i++)
+    bbs[i]->loop_father = outer;
+
+  delete_loop (loop);
+}
+
+/* Cancels LOOP and all its subloops.  */
+void
+cancel_loop_tree (struct loop *loop)
+{
+  while (loop->inner)
+    cancel_loop_tree (loop->inner);
+  cancel_loop (loop);
+}
+
+/* Checks that information about loops is correct
+     -- sizes of loops are all right
+     -- results of get_loop_body really belong to the loop
+     -- loop header have just single entry edge and single latch edge
+     -- loop latches have only single successor that is header of their loop
+     -- irreducible loops are correctly marked
+  */
+void
+verify_loop_structure (void)
+{
+  unsigned *sizes, i, j;
+  sbitmap irreds;
+  basic_block *bbs, bb;
+  struct loop *loop;
+  int err = 0;
+  edge e;
+  unsigned num = number_of_loops ();
+  loop_iterator li;
+  struct loop_exit *exit, *mexit;
+
+  /* Check sizes.  */
+  sizes = XCNEWVEC (unsigned, num);
+  sizes[0] = 2;
+
+  FOR_EACH_BB (bb)
+    for (loop = bb->loop_father; loop; loop = loop_outer (loop))
+      sizes[loop->num]++;
+
+  FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT)
+    {
+      i = loop->num;
+
+      if (loop->num_nodes != sizes[i])
+	{
+	  error ("size of loop %d should be %d, not %d",
+		   i, sizes[i], loop->num_nodes);
+	  err = 1;
+	}
+    }
+
+  /* Check get_loop_body.  */
+  FOR_EACH_LOOP (li, loop, 0)
+    {
+      bbs = get_loop_body (loop);
+
+      for (j = 0; j < loop->num_nodes; j++)
+	if (!flow_bb_inside_loop_p (loop, bbs[j]))
+	  {
+	    error ("bb %d do not belong to loop %d",
+		    bbs[j]->index, loop->num);
+	    err = 1;
+	  }
+      free (bbs);
+    }
+
+  /* Check headers and latches.  */
+  FOR_EACH_LOOP (li, loop, 0)
+    {
+      i = loop->num;
+
+      if (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)
+	  && EDGE_COUNT (loop->header->preds) != 2)
+	{
+	  error ("loop %d's header does not have exactly 2 entries", i);
+	  err = 1;
+	}
+      if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES))
+	{
+	  if (!single_succ_p (loop->latch))
+	    {
+	      error ("loop %d's latch does not have exactly 1 successor", i);
+	      err = 1;
+	    }
+	  if (single_succ (loop->latch) != loop->header)
+	    {
+	      error ("loop %d's latch does not have header as successor", i);
+	      err = 1;
+	    }
+	  if (loop->latch->loop_father != loop)
+	    {
+	      error ("loop %d's latch does not belong directly to it", i);
+	      err = 1;
+	    }
+	}
+      if (loop->header->loop_father != loop)
+	{
+	  error ("loop %d's header does not belong directly to it", i);
+	  err = 1;
+	}
+      if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
+	  && (loop_latch_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP))
+	{
+	  error ("loop %d's latch is marked as part of irreducible region", i);
+	  err = 1;
+	}
+    }
+
+  /* Check irreducible loops.  */
+  if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS))
+    {
+      /* Record old info.  */
+      irreds = sbitmap_alloc (last_basic_block);
+      FOR_EACH_BB (bb)
+	{
+	  edge_iterator ei;
+	  if (bb->flags & BB_IRREDUCIBLE_LOOP)
+	    SET_BIT (irreds, bb->index);
+	  else
+	    RESET_BIT (irreds, bb->index);
+	  FOR_EACH_EDGE (e, ei, bb->succs)
+	    if (e->flags & EDGE_IRREDUCIBLE_LOOP)
+	      e->flags |= EDGE_ALL_FLAGS + 1;
+	}
+
+      /* Recount it.  */
+      mark_irreducible_loops ();
+
+      /* Compare.  */
+      FOR_EACH_BB (bb)
+	{
+	  edge_iterator ei;
+
+	  if ((bb->flags & BB_IRREDUCIBLE_LOOP)
+	      && !TEST_BIT (irreds, bb->index))
+	    {
+	      error ("basic block %d should be marked irreducible", bb->index);
+	      err = 1;
+	    }
+	  else if (!(bb->flags & BB_IRREDUCIBLE_LOOP)
+	      && TEST_BIT (irreds, bb->index))
+	    {
+	      error ("basic block %d should not be marked irreducible", bb->index);
+	      err = 1;
+	    }
+	  FOR_EACH_EDGE (e, ei, bb->succs)
+	    {
+	      if ((e->flags & EDGE_IRREDUCIBLE_LOOP)
+		  && !(e->flags & (EDGE_ALL_FLAGS + 1)))
+		{
+		  error ("edge from %d to %d should be marked irreducible",
+			 e->src->index, e->dest->index);
+		  err = 1;
+		}
+	      else if (!(e->flags & EDGE_IRREDUCIBLE_LOOP)
+		       && (e->flags & (EDGE_ALL_FLAGS + 1)))
+		{
+		  error ("edge from %d to %d should not be marked irreducible",
+			 e->src->index, e->dest->index);
+		  err = 1;
+		}
+	      e->flags &= ~(EDGE_ALL_FLAGS + 1);
+	    }
+	}
+      free (irreds);
+    }
+
+  /* Check the recorded loop exits.  */
+  FOR_EACH_LOOP (li, loop, 0)
+    {
+      if (!loop->exits || loop->exits->e != NULL)
+	{
+	  error ("corrupted head of the exits list of loop %d",
+		 loop->num);
+	  err = 1;
+	}
+      else
+	{
+	  /* Check that the list forms a cycle, and all elements except
+	     for the head are nonnull.  */
+	  for (mexit = loop->exits, exit = mexit->next, i = 0;
+	       exit->e && exit != mexit;
+	       exit = exit->next)
+	    {
+	      if (i++ & 1)
+		mexit = mexit->next;
+	    }
+
+	  if (exit != loop->exits)
+	    {
+	      error ("corrupted exits list of loop %d", loop->num);
+	      err = 1;
+	    }
+	}
+
+      if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
+	{
+	  if (loop->exits->next != loop->exits)
+	    {
+	      error ("nonempty exits list of loop %d, but exits are not recorded",
+		     loop->num);
+	      err = 1;
+	    }
+	}
+    }
+
+  if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
+    {
+      unsigned n_exits = 0, eloops;
+
+      memset (sizes, 0, sizeof (unsigned) * num);
+      FOR_EACH_BB (bb)
+	{
+	  edge_iterator ei;
+	  if (bb->loop_father == current_loops->tree_root)
+	    continue;
+	  FOR_EACH_EDGE (e, ei, bb->succs)
+	    {
+	      if (flow_bb_inside_loop_p (bb->loop_father, e->dest))
+		continue;
+
+	      n_exits++;
+	      exit = get_exit_descriptions (e);
+	      if (!exit)
+		{
+		  error ("Exit %d->%d not recorded", 
+			 e->src->index, e->dest->index);
+		  err = 1;
+		}
+	      eloops = 0;
+	      for (; exit; exit = exit->next_e)
+		eloops++;
+
+	      for (loop = bb->loop_father;
+		   loop != e->dest->loop_father;
+		   loop = loop_outer (loop))
+		{
+		  eloops--;
+		  sizes[loop->num]++;
+		}
+
+	      if (eloops != 0)
+		{
+		  error ("Wrong list of exited loops for edge  %d->%d", 
+			 e->src->index, e->dest->index);
+		  err = 1;
+		}
+	    }
+	}
+
+      if (n_exits != htab_elements (current_loops->exits))
+	{
+	  error ("Too many loop exits recorded");
+	  err = 1;
+	}
+
+      FOR_EACH_LOOP (li, loop, 0)
+	{
+	  eloops = 0;
+	  for (exit = loop->exits->next; exit->e; exit = exit->next)
+	    eloops++;
+	  if (eloops != sizes[loop->num])
+	    {
+	      error ("%d exits recorded for loop %d (having %d exits)",
+		     eloops, loop->num, sizes[loop->num]);
+	      err = 1;
+	    }
+	}
+    }
+
+  gcc_assert (!err);
+
+  free (sizes);
+}
+
+/* Returns latch edge of LOOP.  */
+edge
+loop_latch_edge (const struct loop *loop)
+{
+  return find_edge (loop->latch, loop->header);
+}
+
+/* Returns preheader edge of LOOP.  */
+edge
+loop_preheader_edge (const struct loop *loop)
+{
+  edge e;
+  edge_iterator ei;
+
+  gcc_assert (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS));
+
+  FOR_EACH_EDGE (e, ei, loop->header->preds)
+    if (e->src != loop->latch)
+      break;
+
+  return e;
+}
+
+/* Returns true if E is an exit of LOOP.  */
+
+bool
+loop_exit_edge_p (const struct loop *loop, const_edge e)
+{
+  return (flow_bb_inside_loop_p (loop, e->src)
+	  && !flow_bb_inside_loop_p (loop, e->dest));
+}
+
+/* Returns the single exit edge of LOOP, or NULL if LOOP has either no exit
+   or more than one exit.  If loops do not have the exits recorded, NULL
+   is returned always.  */
+
+edge
+single_exit (const struct loop *loop)
+{
+  struct loop_exit *exit = loop->exits->next;
+
+  if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
+    return NULL;
+
+  if (exit->e && exit->next == loop->exits)
+    return exit->e;
+  else
+    return NULL;
+}
+
+/* Returns true when BB has an edge exiting LOOP.  */
+
+bool
+is_loop_exit (struct loop *loop, basic_block bb)
+{
+  edge e;
+  edge_iterator ei;
+
+  FOR_EACH_EDGE (e, ei, bb->preds)
+    if (loop_exit_edge_p (loop, e))
+      return true;
+
+  return false;
+}