--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/lcm.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,810 @@
+/* Generic partial redundancy elimination with lazy code motion support.
+   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 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/>.  */
+
+/* These routines are meant to be used by various optimization
+   passes which can be modeled as lazy code motion problems.
+   Including, but not limited to:
+
+	* Traditional partial redundancy elimination.
+
+	* Placement of caller/caller register save/restores.
+
+	* Load/store motion.
+
+	* Copy motion.
+
+	* Conversion of flat register files to a stacked register
+	model.
+
+	* Dead load/store elimination.
+
+  These routines accept as input:
+
+	* Basic block information (number of blocks, lists of
+	predecessors and successors).  Note the granularity
+	does not need to be basic block, they could be statements
+	or functions.
+
+	* Bitmaps of local properties (computed, transparent and
+	anticipatable expressions).
+
+  The output of these routines is bitmap of redundant computations
+  and a bitmap of optimal placement points.  */
+
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "rtl.h"
+#include "regs.h"
+#include "hard-reg-set.h"
+#include "flags.h"
+#include "real.h"
+#include "insn-config.h"
+#include "recog.h"
+#include "basic-block.h"
+#include "output.h"
+#include "tm_p.h"
+#include "function.h"
+
+/* We want target macros for the mode switching code to be able to refer
+   to instruction attribute values.  */
+#include "insn-attr.h"
+
+/* Edge based LCM routines.  */
+static void compute_antinout_edge (sbitmap *, sbitmap *, sbitmap *, sbitmap *);
+static void compute_earliest (struct edge_list *, int, sbitmap *, sbitmap *,
+			      sbitmap *, sbitmap *, sbitmap *);
+static void compute_laterin (struct edge_list *, sbitmap *, sbitmap *,
+			     sbitmap *, sbitmap *);
+static void compute_insert_delete (struct edge_list *edge_list, sbitmap *,
+				   sbitmap *, sbitmap *, sbitmap *, sbitmap *);
+
+/* Edge based LCM routines on a reverse flowgraph.  */
+static void compute_farthest (struct edge_list *, int, sbitmap *, sbitmap *,
+			      sbitmap*, sbitmap *, sbitmap *);
+static void compute_nearerout (struct edge_list *, sbitmap *, sbitmap *,
+			       sbitmap *, sbitmap *);
+static void compute_rev_insert_delete (struct edge_list *edge_list, sbitmap *,
+				       sbitmap *, sbitmap *, sbitmap *,
+				       sbitmap *);
+
+/* Edge based lcm routines.  */
+
+/* Compute expression anticipatability at entrance and exit of each block.
+   This is done based on the flow graph, and not on the pred-succ lists.
+   Other than that, its pretty much identical to compute_antinout.  */
+
+static void
+compute_antinout_edge (sbitmap *antloc, sbitmap *transp, sbitmap *antin,
+		       sbitmap *antout)
+{
+  basic_block bb;
+  edge e;
+  basic_block *worklist, *qin, *qout, *qend;
+  unsigned int qlen;
+  edge_iterator ei;
+
+  /* Allocate a worklist array/queue.  Entries are only added to the
+     list if they were not already on the list.  So the size is
+     bounded by the number of basic blocks.  */
+  qin = qout = worklist = XNEWVEC (basic_block, n_basic_blocks);
+
+  /* We want a maximal solution, so make an optimistic initialization of
+     ANTIN.  */
+  sbitmap_vector_ones (antin, last_basic_block);
+
+  /* Put every block on the worklist; this is necessary because of the
+     optimistic initialization of ANTIN above.  */
+  FOR_EACH_BB_REVERSE (bb)
+    {
+      *qin++ = bb;
+      bb->aux = bb;
+    }
+
+  qin = worklist;
+  qend = &worklist[n_basic_blocks - NUM_FIXED_BLOCKS];
+  qlen = n_basic_blocks - NUM_FIXED_BLOCKS;
+
+  /* Mark blocks which are predecessors of the exit block so that we
+     can easily identify them below.  */
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
+    e->src->aux = EXIT_BLOCK_PTR;
+
+  /* Iterate until the worklist is empty.  */
+  while (qlen)
+    {
+      /* Take the first entry off the worklist.  */
+      bb = *qout++;
+      qlen--;
+
+      if (qout >= qend)
+	qout = worklist;
+
+      if (bb->aux == EXIT_BLOCK_PTR)
+	/* Do not clear the aux field for blocks which are predecessors of
+	   the EXIT block.  That way we never add then to the worklist
+	   again.  */
+	sbitmap_zero (antout[bb->index]);
+      else
+	{
+	  /* Clear the aux field of this block so that it can be added to
+	     the worklist again if necessary.  */
+	  bb->aux = NULL;
+	  sbitmap_intersection_of_succs (antout[bb->index], antin, bb->index);
+	}
+
+      if (sbitmap_a_or_b_and_c_cg (antin[bb->index], antloc[bb->index],
+				   transp[bb->index], antout[bb->index]))
+	/* If the in state of this block changed, then we need
+	   to add the predecessors of this block to the worklist
+	   if they are not already on the worklist.  */
+	FOR_EACH_EDGE (e, ei, bb->preds)
+	  if (!e->src->aux && e->src != ENTRY_BLOCK_PTR)
+	    {
+	      *qin++ = e->src;
+	      e->src->aux = e;
+	      qlen++;
+	      if (qin >= qend)
+		qin = worklist;
+	    }
+    }
+
+  clear_aux_for_edges ();
+  clear_aux_for_blocks ();
+  free (worklist);
+}
+
+/* Compute the earliest vector for edge based lcm.  */
+
+static void
+compute_earliest (struct edge_list *edge_list, int n_exprs, sbitmap *antin,
+		  sbitmap *antout, sbitmap *avout, sbitmap *kill,
+		  sbitmap *earliest)
+{
+  sbitmap difference, temp_bitmap;
+  int x, num_edges;
+  basic_block pred, succ;
+
+  num_edges = NUM_EDGES (edge_list);
+
+  difference = sbitmap_alloc (n_exprs);
+  temp_bitmap = sbitmap_alloc (n_exprs);
+
+  for (x = 0; x < num_edges; x++)
+    {
+      pred = INDEX_EDGE_PRED_BB (edge_list, x);
+      succ = INDEX_EDGE_SUCC_BB (edge_list, x);
+      if (pred == ENTRY_BLOCK_PTR)
+	sbitmap_copy (earliest[x], antin[succ->index]);
+      else
+	{
+	  if (succ == EXIT_BLOCK_PTR)
+	    sbitmap_zero (earliest[x]);
+	  else
+	    {
+	      sbitmap_difference (difference, antin[succ->index],
+				  avout[pred->index]);
+	      sbitmap_not (temp_bitmap, antout[pred->index]);
+	      sbitmap_a_and_b_or_c (earliest[x], difference,
+				    kill[pred->index], temp_bitmap);
+	    }
+	}
+    }
+
+  sbitmap_free (temp_bitmap);
+  sbitmap_free (difference);
+}
+
+/* later(p,s) is dependent on the calculation of laterin(p).
+   laterin(p) is dependent on the calculation of later(p2,p).
+
+     laterin(ENTRY) is defined as all 0's
+     later(ENTRY, succs(ENTRY)) are defined using laterin(ENTRY)
+     laterin(succs(ENTRY)) is defined by later(ENTRY, succs(ENTRY)).
+
+   If we progress in this manner, starting with all basic blocks
+   in the work list, anytime we change later(bb), we need to add
+   succs(bb) to the worklist if they are not already on the worklist.
+
+   Boundary conditions:
+
+     We prime the worklist all the normal basic blocks.   The ENTRY block can
+     never be added to the worklist since it is never the successor of any
+     block.  We explicitly prevent the EXIT block from being added to the
+     worklist.
+
+     We optimistically initialize LATER.  That is the only time this routine
+     will compute LATER for an edge out of the entry block since the entry
+     block is never on the worklist.  Thus, LATERIN is neither used nor
+     computed for the ENTRY block.
+
+     Since the EXIT block is never added to the worklist, we will neither
+     use nor compute LATERIN for the exit block.  Edges which reach the
+     EXIT block are handled in the normal fashion inside the loop.  However,
+     the insertion/deletion computation needs LATERIN(EXIT), so we have
+     to compute it.  */
+
+static void
+compute_laterin (struct edge_list *edge_list, sbitmap *earliest,
+		 sbitmap *antloc, sbitmap *later, sbitmap *laterin)
+{
+  int num_edges, i;
+  edge e;
+  basic_block *worklist, *qin, *qout, *qend, bb;
+  unsigned int qlen;
+  edge_iterator ei;
+
+  num_edges = NUM_EDGES (edge_list);
+
+  /* Allocate a worklist array/queue.  Entries are only added to the
+     list if they were not already on the list.  So the size is
+     bounded by the number of basic blocks.  */
+  qin = qout = worklist
+    = XNEWVEC (basic_block, n_basic_blocks);
+
+  /* Initialize a mapping from each edge to its index.  */
+  for (i = 0; i < num_edges; i++)
+    INDEX_EDGE (edge_list, i)->aux = (void *) (size_t) i;
+
+  /* We want a maximal solution, so initially consider LATER true for
+     all edges.  This allows propagation through a loop since the incoming
+     loop edge will have LATER set, so if all the other incoming edges
+     to the loop are set, then LATERIN will be set for the head of the
+     loop.
+
+     If the optimistic setting of LATER on that edge was incorrect (for
+     example the expression is ANTLOC in a block within the loop) then
+     this algorithm will detect it when we process the block at the head
+     of the optimistic edge.  That will requeue the affected blocks.  */
+  sbitmap_vector_ones (later, num_edges);
+
+  /* Note that even though we want an optimistic setting of LATER, we
+     do not want to be overly optimistic.  Consider an outgoing edge from
+     the entry block.  That edge should always have a LATER value the
+     same as EARLIEST for that edge.  */
+  FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
+    sbitmap_copy (later[(size_t) e->aux], earliest[(size_t) e->aux]);
+
+  /* Add all the blocks to the worklist.  This prevents an early exit from
+     the loop given our optimistic initialization of LATER above.  */
+  FOR_EACH_BB (bb)
+    {
+      *qin++ = bb;
+      bb->aux = bb;
+    }
+
+  /* Note that we do not use the last allocated element for our queue,
+     as EXIT_BLOCK is never inserted into it. */
+  qin = worklist;
+  qend = &worklist[n_basic_blocks - NUM_FIXED_BLOCKS];
+  qlen = n_basic_blocks - NUM_FIXED_BLOCKS;
+
+  /* Iterate until the worklist is empty.  */
+  while (qlen)
+    {
+      /* Take the first entry off the worklist.  */
+      bb = *qout++;
+      bb->aux = NULL;
+      qlen--;
+      if (qout >= qend)
+	qout = worklist;
+
+      /* Compute the intersection of LATERIN for each incoming edge to B.  */
+      sbitmap_ones (laterin[bb->index]);
+      FOR_EACH_EDGE (e, ei, bb->preds)
+	sbitmap_a_and_b (laterin[bb->index], laterin[bb->index],
+			 later[(size_t)e->aux]);
+
+      /* Calculate LATER for all outgoing edges.  */
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	if (sbitmap_union_of_diff_cg (later[(size_t) e->aux],
+				      earliest[(size_t) e->aux],
+				      laterin[e->src->index],
+				      antloc[e->src->index])
+	    /* If LATER for an outgoing edge was changed, then we need
+	       to add the target of the outgoing edge to the worklist.  */
+	    && e->dest != EXIT_BLOCK_PTR && e->dest->aux == 0)
+	  {
+	    *qin++ = e->dest;
+	    e->dest->aux = e;
+	    qlen++;
+	    if (qin >= qend)
+	      qin = worklist;
+	  }
+    }
+
+  /* Computation of insertion and deletion points requires computing LATERIN
+     for the EXIT block.  We allocated an extra entry in the LATERIN array
+     for just this purpose.  */
+  sbitmap_ones (laterin[last_basic_block]);
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
+    sbitmap_a_and_b (laterin[last_basic_block],
+		     laterin[last_basic_block],
+		     later[(size_t) e->aux]);
+
+  clear_aux_for_edges ();
+  free (worklist);
+}
+
+/* Compute the insertion and deletion points for edge based LCM.  */
+
+static void
+compute_insert_delete (struct edge_list *edge_list, sbitmap *antloc,
+		       sbitmap *later, sbitmap *laterin, sbitmap *insert,
+		       sbitmap *del)
+{
+  int x;
+  basic_block bb;
+
+  FOR_EACH_BB (bb)
+    sbitmap_difference (del[bb->index], antloc[bb->index],
+			laterin[bb->index]);
+
+  for (x = 0; x < NUM_EDGES (edge_list); x++)
+    {
+      basic_block b = INDEX_EDGE_SUCC_BB (edge_list, x);
+
+      if (b == EXIT_BLOCK_PTR)
+	sbitmap_difference (insert[x], later[x], laterin[last_basic_block]);
+      else
+	sbitmap_difference (insert[x], later[x], laterin[b->index]);
+    }
+}
+
+/* Given local properties TRANSP, ANTLOC, AVOUT, KILL return the insert and
+   delete vectors for edge based LCM.  Returns an edgelist which is used to
+   map the insert vector to what edge an expression should be inserted on.  */
+
+struct edge_list *
+pre_edge_lcm (int n_exprs, sbitmap *transp,
+	      sbitmap *avloc, sbitmap *antloc, sbitmap *kill,
+	      sbitmap **insert, sbitmap **del)
+{
+  sbitmap *antin, *antout, *earliest;
+  sbitmap *avin, *avout;
+  sbitmap *later, *laterin;
+  struct edge_list *edge_list;
+  int num_edges;
+
+  edge_list = create_edge_list ();
+  num_edges = NUM_EDGES (edge_list);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    {
+      fprintf (dump_file, "Edge List:\n");
+      verify_edge_list (dump_file, edge_list);
+      print_edge_list (dump_file, edge_list);
+      dump_sbitmap_vector (dump_file, "transp", "", transp, last_basic_block);
+      dump_sbitmap_vector (dump_file, "antloc", "", antloc, last_basic_block);
+      dump_sbitmap_vector (dump_file, "avloc", "", avloc, last_basic_block);
+      dump_sbitmap_vector (dump_file, "kill", "", kill, last_basic_block);
+    }
+#endif
+
+  /* Compute global availability.  */
+  avin = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  avout = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  compute_available (avloc, kill, avout, avin);
+  sbitmap_vector_free (avin);
+
+  /* Compute global anticipatability.  */
+  antin = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  antout = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  compute_antinout_edge (antloc, transp, antin, antout);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    {
+      dump_sbitmap_vector (dump_file, "antin", "", antin, last_basic_block);
+      dump_sbitmap_vector (dump_file, "antout", "", antout, last_basic_block);
+    }
+#endif
+
+  /* Compute earliestness.  */
+  earliest = sbitmap_vector_alloc (num_edges, n_exprs);
+  compute_earliest (edge_list, n_exprs, antin, antout, avout, kill, earliest);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    dump_sbitmap_vector (dump_file, "earliest", "", earliest, num_edges);
+#endif
+
+  sbitmap_vector_free (antout);
+  sbitmap_vector_free (antin);
+  sbitmap_vector_free (avout);
+
+  later = sbitmap_vector_alloc (num_edges, n_exprs);
+
+  /* Allocate an extra element for the exit block in the laterin vector.  */
+  laterin = sbitmap_vector_alloc (last_basic_block + 1, n_exprs);
+  compute_laterin (edge_list, earliest, antloc, later, laterin);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    {
+      dump_sbitmap_vector (dump_file, "laterin", "", laterin, last_basic_block + 1);
+      dump_sbitmap_vector (dump_file, "later", "", later, num_edges);
+    }
+#endif
+
+  sbitmap_vector_free (earliest);
+
+  *insert = sbitmap_vector_alloc (num_edges, n_exprs);
+  *del = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  compute_insert_delete (edge_list, antloc, later, laterin, *insert, *del);
+
+  sbitmap_vector_free (laterin);
+  sbitmap_vector_free (later);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    {
+      dump_sbitmap_vector (dump_file, "pre_insert_map", "", *insert, num_edges);
+      dump_sbitmap_vector (dump_file, "pre_delete_map", "", *del,
+			   last_basic_block);
+    }
+#endif
+
+  return edge_list;
+}
+
+/* Compute the AVIN and AVOUT vectors from the AVLOC and KILL vectors.
+   Return the number of passes we performed to iterate to a solution.  */
+
+void
+compute_available (sbitmap *avloc, sbitmap *kill, sbitmap *avout,
+		   sbitmap *avin)
+{
+  edge e;
+  basic_block *worklist, *qin, *qout, *qend, bb;
+  unsigned int qlen;
+  edge_iterator ei;
+
+  /* Allocate a worklist array/queue.  Entries are only added to the
+     list if they were not already on the list.  So the size is
+     bounded by the number of basic blocks.  */
+  qin = qout = worklist = 
+    XNEWVEC (basic_block, n_basic_blocks - NUM_FIXED_BLOCKS);
+
+  /* We want a maximal solution.  */
+  sbitmap_vector_ones (avout, last_basic_block);
+
+  /* Put every block on the worklist; this is necessary because of the
+     optimistic initialization of AVOUT above.  */
+  FOR_EACH_BB (bb)
+    {
+      *qin++ = bb;
+      bb->aux = bb;
+    }
+
+  qin = worklist;
+  qend = &worklist[n_basic_blocks - NUM_FIXED_BLOCKS];
+  qlen = n_basic_blocks - NUM_FIXED_BLOCKS;
+
+  /* Mark blocks which are successors of the entry block so that we
+     can easily identify them below.  */
+  FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
+    e->dest->aux = ENTRY_BLOCK_PTR;
+
+  /* Iterate until the worklist is empty.  */
+  while (qlen)
+    {
+      /* Take the first entry off the worklist.  */
+      bb = *qout++;
+      qlen--;
+
+      if (qout >= qend)
+	qout = worklist;
+
+      /* If one of the predecessor blocks is the ENTRY block, then the
+	 intersection of avouts is the null set.  We can identify such blocks
+	 by the special value in the AUX field in the block structure.  */
+      if (bb->aux == ENTRY_BLOCK_PTR)
+	/* Do not clear the aux field for blocks which are successors of the
+	   ENTRY block.  That way we never add then to the worklist again.  */
+	sbitmap_zero (avin[bb->index]);
+      else
+	{
+	  /* Clear the aux field of this block so that it can be added to
+	     the worklist again if necessary.  */
+	  bb->aux = NULL;
+	  sbitmap_intersection_of_preds (avin[bb->index], avout, bb->index);
+	}
+
+      if (sbitmap_union_of_diff_cg (avout[bb->index], avloc[bb->index],
+				    avin[bb->index], kill[bb->index]))
+	/* If the out state of this block changed, then we need
+	   to add the successors of this block to the worklist
+	   if they are not already on the worklist.  */
+	FOR_EACH_EDGE (e, ei, bb->succs)
+	  if (!e->dest->aux && e->dest != EXIT_BLOCK_PTR)
+	    {
+	      *qin++ = e->dest;
+	      e->dest->aux = e;
+	      qlen++;
+
+	      if (qin >= qend)
+		qin = worklist;
+	    }
+    }
+
+  clear_aux_for_edges ();
+  clear_aux_for_blocks ();
+  free (worklist);
+}
+
+/* Compute the farthest vector for edge based lcm.  */
+
+static void
+compute_farthest (struct edge_list *edge_list, int n_exprs,
+		  sbitmap *st_avout, sbitmap *st_avin, sbitmap *st_antin,
+		  sbitmap *kill, sbitmap *farthest)
+{
+  sbitmap difference, temp_bitmap;
+  int x, num_edges;
+  basic_block pred, succ;
+
+  num_edges = NUM_EDGES (edge_list);
+
+  difference = sbitmap_alloc (n_exprs);
+  temp_bitmap = sbitmap_alloc (n_exprs);
+
+  for (x = 0; x < num_edges; x++)
+    {
+      pred = INDEX_EDGE_PRED_BB (edge_list, x);
+      succ = INDEX_EDGE_SUCC_BB (edge_list, x);
+      if (succ == EXIT_BLOCK_PTR)
+	sbitmap_copy (farthest[x], st_avout[pred->index]);
+      else
+	{
+	  if (pred == ENTRY_BLOCK_PTR)
+	    sbitmap_zero (farthest[x]);
+	  else
+	    {
+	      sbitmap_difference (difference, st_avout[pred->index],
+				  st_antin[succ->index]);
+	      sbitmap_not (temp_bitmap, st_avin[succ->index]);
+	      sbitmap_a_and_b_or_c (farthest[x], difference,
+				    kill[succ->index], temp_bitmap);
+	    }
+	}
+    }
+
+  sbitmap_free (temp_bitmap);
+  sbitmap_free (difference);
+}
+
+/* Compute nearer and nearerout vectors for edge based lcm.
+
+   This is the mirror of compute_laterin, additional comments on the
+   implementation can be found before compute_laterin.  */
+
+static void
+compute_nearerout (struct edge_list *edge_list, sbitmap *farthest,
+		   sbitmap *st_avloc, sbitmap *nearer, sbitmap *nearerout)
+{
+  int num_edges, i;
+  edge e;
+  basic_block *worklist, *tos, bb;
+  edge_iterator ei;
+
+  num_edges = NUM_EDGES (edge_list);
+
+  /* Allocate a worklist array/queue.  Entries are only added to the
+     list if they were not already on the list.  So the size is
+     bounded by the number of basic blocks.  */
+  tos = worklist = XNEWVEC (basic_block, n_basic_blocks + 1);
+
+  /* Initialize NEARER for each edge and build a mapping from an edge to
+     its index.  */
+  for (i = 0; i < num_edges; i++)
+    INDEX_EDGE (edge_list, i)->aux = (void *) (size_t) i;
+
+  /* We want a maximal solution.  */
+  sbitmap_vector_ones (nearer, num_edges);
+
+  /* Note that even though we want an optimistic setting of NEARER, we
+     do not want to be overly optimistic.  Consider an incoming edge to
+     the exit block.  That edge should always have a NEARER value the
+     same as FARTHEST for that edge.  */
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
+    sbitmap_copy (nearer[(size_t)e->aux], farthest[(size_t)e->aux]);
+
+  /* Add all the blocks to the worklist.  This prevents an early exit
+     from the loop given our optimistic initialization of NEARER.  */
+  FOR_EACH_BB (bb)
+    {
+      *tos++ = bb;
+      bb->aux = bb;
+    }
+
+  /* Iterate until the worklist is empty.  */
+  while (tos != worklist)
+    {
+      /* Take the first entry off the worklist.  */
+      bb = *--tos;
+      bb->aux = NULL;
+
+      /* Compute the intersection of NEARER for each outgoing edge from B.  */
+      sbitmap_ones (nearerout[bb->index]);
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	sbitmap_a_and_b (nearerout[bb->index], nearerout[bb->index],
+			 nearer[(size_t) e->aux]);
+
+      /* Calculate NEARER for all incoming edges.  */
+      FOR_EACH_EDGE (e, ei, bb->preds)
+	if (sbitmap_union_of_diff_cg (nearer[(size_t) e->aux],
+				      farthest[(size_t) e->aux],
+				      nearerout[e->dest->index],
+				      st_avloc[e->dest->index])
+	    /* If NEARER for an incoming edge was changed, then we need
+	       to add the source of the incoming edge to the worklist.  */
+	    && e->src != ENTRY_BLOCK_PTR && e->src->aux == 0)
+	  {
+	    *tos++ = e->src;
+	    e->src->aux = e;
+	  }
+    }
+
+  /* Computation of insertion and deletion points requires computing NEAREROUT
+     for the ENTRY block.  We allocated an extra entry in the NEAREROUT array
+     for just this purpose.  */
+  sbitmap_ones (nearerout[last_basic_block]);
+  FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
+    sbitmap_a_and_b (nearerout[last_basic_block],
+		     nearerout[last_basic_block],
+		     nearer[(size_t) e->aux]);
+
+  clear_aux_for_edges ();
+  free (tos);
+}
+
+/* Compute the insertion and deletion points for edge based LCM.  */
+
+static void
+compute_rev_insert_delete (struct edge_list *edge_list, sbitmap *st_avloc,
+			   sbitmap *nearer, sbitmap *nearerout,
+			   sbitmap *insert, sbitmap *del)
+{
+  int x;
+  basic_block bb;
+
+  FOR_EACH_BB (bb)
+    sbitmap_difference (del[bb->index], st_avloc[bb->index],
+			nearerout[bb->index]);
+
+  for (x = 0; x < NUM_EDGES (edge_list); x++)
+    {
+      basic_block b = INDEX_EDGE_PRED_BB (edge_list, x);
+      if (b == ENTRY_BLOCK_PTR)
+	sbitmap_difference (insert[x], nearer[x], nearerout[last_basic_block]);
+      else
+	sbitmap_difference (insert[x], nearer[x], nearerout[b->index]);
+    }
+}
+
+/* Given local properties TRANSP, ST_AVLOC, ST_ANTLOC, KILL return the
+   insert and delete vectors for edge based reverse LCM.  Returns an
+   edgelist which is used to map the insert vector to what edge
+   an expression should be inserted on.  */
+
+struct edge_list *
+pre_edge_rev_lcm (int n_exprs, sbitmap *transp,
+		  sbitmap *st_avloc, sbitmap *st_antloc, sbitmap *kill,
+		  sbitmap **insert, sbitmap **del)
+{
+  sbitmap *st_antin, *st_antout;
+  sbitmap *st_avout, *st_avin, *farthest;
+  sbitmap *nearer, *nearerout;
+  struct edge_list *edge_list;
+  int num_edges;
+
+  edge_list = create_edge_list ();
+  num_edges = NUM_EDGES (edge_list);
+
+  st_antin = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  st_antout = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  sbitmap_vector_zero (st_antin, last_basic_block);
+  sbitmap_vector_zero (st_antout, last_basic_block);
+  compute_antinout_edge (st_antloc, transp, st_antin, st_antout);
+
+  /* Compute global anticipatability.  */
+  st_avout = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  st_avin = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  compute_available (st_avloc, kill, st_avout, st_avin);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    {
+      fprintf (dump_file, "Edge List:\n");
+      verify_edge_list (dump_file, edge_list);
+      print_edge_list (dump_file, edge_list);
+      dump_sbitmap_vector (dump_file, "transp", "", transp, last_basic_block);
+      dump_sbitmap_vector (dump_file, "st_avloc", "", st_avloc, last_basic_block);
+      dump_sbitmap_vector (dump_file, "st_antloc", "", st_antloc, last_basic_block);
+      dump_sbitmap_vector (dump_file, "st_antin", "", st_antin, last_basic_block);
+      dump_sbitmap_vector (dump_file, "st_antout", "", st_antout, last_basic_block);
+      dump_sbitmap_vector (dump_file, "st_kill", "", kill, last_basic_block);
+    }
+#endif
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    {
+      dump_sbitmap_vector (dump_file, "st_avout", "", st_avout, last_basic_block);
+      dump_sbitmap_vector (dump_file, "st_avin", "", st_avin, last_basic_block);
+    }
+#endif
+
+  /* Compute farthestness.  */
+  farthest = sbitmap_vector_alloc (num_edges, n_exprs);
+  compute_farthest (edge_list, n_exprs, st_avout, st_avin, st_antin,
+		    kill, farthest);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    dump_sbitmap_vector (dump_file, "farthest", "", farthest, num_edges);
+#endif
+
+  sbitmap_vector_free (st_antin);
+  sbitmap_vector_free (st_antout);
+
+  sbitmap_vector_free (st_avin);
+  sbitmap_vector_free (st_avout);
+
+  nearer = sbitmap_vector_alloc (num_edges, n_exprs);
+
+  /* Allocate an extra element for the entry block.  */
+  nearerout = sbitmap_vector_alloc (last_basic_block + 1, n_exprs);
+  compute_nearerout (edge_list, farthest, st_avloc, nearer, nearerout);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    {
+      dump_sbitmap_vector (dump_file, "nearerout", "", nearerout,
+			   last_basic_block + 1);
+      dump_sbitmap_vector (dump_file, "nearer", "", nearer, num_edges);
+    }
+#endif
+
+  sbitmap_vector_free (farthest);
+
+  *insert = sbitmap_vector_alloc (num_edges, n_exprs);
+  *del = sbitmap_vector_alloc (last_basic_block, n_exprs);
+  compute_rev_insert_delete (edge_list, st_avloc, nearer, nearerout,
+			     *insert, *del);
+
+  sbitmap_vector_free (nearerout);
+  sbitmap_vector_free (nearer);
+
+#ifdef LCM_DEBUG_INFO
+  if (dump_file)
+    {
+      dump_sbitmap_vector (dump_file, "pre_insert_map", "", *insert, num_edges);
+      dump_sbitmap_vector (dump_file, "pre_delete_map", "", *del,
+			   last_basic_block);
+    }
+#endif
+  return edge_list;
+}
+