/* Convert a program in SSA form into Normal form.
   Copyright (C) 2004 Free Software Foundation, Inc.
   Contributed by Andrew Macleod <amacleod@redhat.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later 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 COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "flags.h"
#include "rtl.h"
#include "tm_p.h"
#include "ggc.h"
#include "langhooks.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "output.h"
#include "errors.h"
#include "expr.h"
#include "function.h"
#include "diagnostic.h"
#include "bitmap.h"
#include "tree-flow.h"
#include "tree-simple.h"
#include "tree-inline.h"
#include "varray.h"
#include "timevar.h"
#include "tree-alias-common.h"
#include "hashtab.h"
#include "tree-dump.h"
#include "tree-ssa-live.h"
#include "tree-pass.h"

/* Used to hold all the components required to do SSA PHI elimination.
   The node and pred/succ list is a simple linear list of nodes and
   edges represented as pairs of nodes.

   The predecessor and successor list:  Nodes are entered in pairs, where
   [0] ->PRED, [1]->SUCC.  All the even indexes in the array represent 
   predecessors, all the odd elements are successors. 
   
   Rationale:
   When implemented as bitmaps, very large programs SSA->Normal times were 
   being dominated by clearing the interference graph.

   Typically this list of edges is extremely small since it only includes 
   PHI results and uses from a single edge which have not coalesced with 
   each other.  This means that no virtual PHI nodes are included, and
   empirical evidence suggests that the number of edges rarely exceed
   3, and in a bootstrap of GCC, the maximum size encountered was 7.
   This also limits the number of possible nodes that are involved to
   rarely more than 6, and in the bootstrap of gcc, the maximum number
   of nodes encountered was 12.  */
 
typedef struct _elim_graph {
  /* Size of the elimination vectors.  */
  int size;

  /* List of nodes in the elimination graph.  */
  varray_type nodes;

  /*  The predecessor and successor edge list. */
  varray_type edge_list;

  /* Visited vector.  */
  sbitmap visited;

  /* Stack for visited nodes.  */
  varray_type stack;
  
  /* The variable partition map.  */
  var_map map;

  /* Edge being eliminated by this graph.  */
  edge e;

  /* List of constant copies to emit.  These are pushed on in pairs.  */
  varray_type  const_copies;
} *elim_graph;


/* Local functions.  */
static tree create_temp (tree);
static void insert_copy_on_edge (edge, tree, tree);
static elim_graph new_elim_graph (int);
static inline void delete_elim_graph (elim_graph);
static inline void clear_elim_graph (elim_graph);
static inline int elim_graph_size (elim_graph);
static inline void elim_graph_add_node (elim_graph, tree);
static inline void elim_graph_add_edge (elim_graph, int, int);
static inline int elim_graph_remove_succ_edge (elim_graph, int);

static inline void eliminate_name (elim_graph, tree);
static void eliminate_build (elim_graph, basic_block, int);
static void elim_forward (elim_graph, int);
static int elim_unvisited_predecessor (elim_graph, int);
static void elim_backward (elim_graph, int);
static void elim_create (elim_graph, int);
static void eliminate_phi (edge, int, elim_graph);
static tree_live_info_p coalesce_ssa_name (var_map, int);
static void assign_vars (var_map);
static bool replace_variable (var_map, tree *, tree *);
static void eliminate_virtual_phis (void);
static void coalesce_abnormal_edges (var_map, conflict_graph, root_var_p);
static void print_exprs (FILE *, const char *, tree, const char *, tree,
			 const char *);
static void print_exprs_edge (FILE *, edge, const char *, tree, const char *,
			      tree);


/* Create a temporary for a partition based on the type of variable T,
   which already represents a partition.  */

static tree
create_temp (tree t)
{
  tree tmp;
  const char *name = NULL;
  tree type;

  if (TREE_CODE (t) == SSA_NAME)
    t = SSA_NAME_VAR (t);
 
  if (TREE_CODE (t) != VAR_DECL 
      && TREE_CODE (t) != PARM_DECL)
    abort ();

  type = TREE_TYPE (t);
  tmp = DECL_NAME (t);
  if (tmp)
    name = IDENTIFIER_POINTER (tmp);

  if (name == NULL)
    name = "temp";
  tmp = create_tmp_var (type, name);
  DECL_ARTIFICIAL (tmp) = DECL_ARTIFICIAL (t);
  add_referenced_tmp_var (tmp);

  /* add_referenced_tmp_var will create the annotation and set up some
     of the flags in the annotation.  However, some flags we need to
     inherit from our original variable.  */
  var_ann (tmp)->type_mem_tag = var_ann (t)->type_mem_tag;
  if (is_call_clobbered (t))
    mark_call_clobbered (tmp);

  return tmp;
}


/* This helper function fill insert a copy from a constant or a variable to 
   a variable on the specified edge.  */

static void
insert_copy_on_edge (edge e, tree dest, tree src)
{
  tree copy;

  copy = build (MODIFY_EXPR, TREE_TYPE (dest), dest, src);
  set_is_used (dest);

  if (TREE_CODE (src) == ADDR_EXPR)
    src = TREE_OPERAND (src, 0);
  if (TREE_CODE (src) == VAR_DECL || TREE_CODE (src) == PARM_DECL)
    set_is_used (src);

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file,
	       "Inserting a copy on edge BB%d->BB%d :",
	       e->src->index,
	       e->dest->index);
      print_generic_expr (dump_file, copy, dump_flags);
      fprintf (dump_file, "\n");
    }

  bsi_insert_on_edge (e, copy);
}

/* --------------------------------------------------------------------- */
/* Create an elimination graph and associated data structures.  */

static elim_graph
new_elim_graph (int size)
{
  elim_graph g = (elim_graph) xmalloc (sizeof (struct _elim_graph));

  VARRAY_TREE_INIT (g->nodes, 30, "Elimination Node List");
  VARRAY_TREE_INIT (g->const_copies, 20, "Elimination Constant Copies");
  VARRAY_INT_INIT (g->edge_list, 20, "Elimination Edge List");
  VARRAY_INT_INIT (g->stack, 30, " Elimination Stack");
  
  g->visited = sbitmap_alloc (size);

  return g;
}


/* Empty the elimination graph.  */
static inline void
clear_elim_graph (elim_graph g)
{
  VARRAY_POP_ALL (g->nodes);
  VARRAY_POP_ALL (g->edge_list);
}


/* Delete an elimination graph.  */
static inline void
delete_elim_graph (elim_graph g)
{
  sbitmap_free (g->visited);
  free (g);
}


/* Return the number of nodes in the graph.  */
static inline int
elim_graph_size (elim_graph g)
{
  return VARRAY_ACTIVE_SIZE (g->nodes);
}


/* Add a node to the graph, if it doesn't exist already.  */
static inline void 
elim_graph_add_node (elim_graph g, tree node)
{
  int x;
  for (x = 0; x < elim_graph_size (g); x++)
    if (VARRAY_TREE (g->nodes, x) == node)
      return;
  VARRAY_PUSH_TREE (g->nodes, node);
}


/* Add an edge to the graph.  */
static inline void
elim_graph_add_edge (elim_graph g, int pred, int succ)
{
  VARRAY_PUSH_INT (g->edge_list, pred);
  VARRAY_PUSH_INT (g->edge_list, succ);
}


/* Remove an edge from the graph for which node is the predecessor, and
   return the successor node.  -1 is returned if there is no such edge.  */
static inline int
elim_graph_remove_succ_edge (elim_graph g, int node)
{
  int y;
  unsigned x;
  for (x = 0; x < VARRAY_ACTIVE_SIZE (g->edge_list); x += 2)
    if (VARRAY_INT (g->edge_list, x) == node)
      {
        VARRAY_INT (g->edge_list, x) = -1;
	y = VARRAY_INT (g->edge_list, x + 1);
	VARRAY_INT (g->edge_list, x + 1) = -1;
	return y;
      }
  return -1;
}

/* Find all the nodes which are successors to NODE in the edge list.  */
#define FOR_EACH_ELIM_GRAPH_SUCC(GRAPH, NODE, VAR, CODE)		\
do {									\
  unsigned x_;								\
  int y_;								\
  for (x_ = 0; x_ < VARRAY_ACTIVE_SIZE ((GRAPH)->edge_list); x_ += 2)	\
    {									\
      y_ = VARRAY_INT ((GRAPH)->edge_list, x_);				\
      if (y_ != (NODE))							\
        continue;							\
      (VAR) = VARRAY_INT ((GRAPH)->edge_list, x_ + 1);			\
      CODE;								\
    }									\
} while (0)

/* Find all the nodes which are predecessors of NODE in the edge list.  */
#define FOR_EACH_ELIM_GRAPH_PRED(GRAPH, NODE, VAR, CODE)		\
do {									\
  unsigned x_;								\
  int y_;								\
  for (x_ = 0; x_ < VARRAY_ACTIVE_SIZE ((GRAPH)->edge_list); x_ += 2)	\
    {									\
      y_ = VARRAY_INT ((GRAPH)->edge_list, x_ + 1);			\
      if (y_ != (NODE))							\
        continue;							\
      (VAR) = VARRAY_INT ((GRAPH)->edge_list, x_);			\
      CODE;								\
    }									\
} while (0)


/* Add T to the elimination graph.  */

static inline void
eliminate_name (elim_graph g, tree T)
{
  elim_graph_add_node (g, T);
}

/* Build the auxiliary graph.  */

static void
eliminate_build (elim_graph g, basic_block B, int i)
{
  tree phi;
  tree T0, Ti;
  int p0, pi;

  clear_elim_graph (g);
  
  for (phi = phi_nodes (B); phi; phi = TREE_CHAIN (phi))
    {
      T0 = var_to_partition_to_var (g->map, PHI_RESULT (phi));
      /* Ignore results which are not in partitions.  */
      if (T0 == NULL_TREE)
        {
#ifdef ENABLE_CHECKING
	  /* There should be no arguments of this PHI which are in
	     the partition list, or we get incorrect results.  */
	  for (pi = 0; pi < PHI_NUM_ARGS (phi); pi++)
	    {
	      tree arg = PHI_ARG_DEF (phi, pi);
	      if (TREE_CODE (arg) == SSA_NAME
		  && var_to_partition (g->map, arg) != NO_PARTITION)
		{
		  fprintf (stderr, "Argument of PHI is in a partition :(");
		  print_generic_expr (stderr, arg, TDF_SLIM);
		  fprintf (stderr, "), but the result is not :");
		  print_generic_stmt (stderr, phi, TDF_SLIM);
		  abort();
		}
	    }
#endif
	  continue;
	}
      if (PHI_ARG_EDGE (phi, i) == g->e)
	Ti = PHI_ARG_DEF (phi, i);
      else
        {
	  /* On rare occasions, a PHI node may not have the arguments
	     in the same order as all of the other PHI nodes. If they don't 
	     match, find the appropriate index here.  */
	  pi = phi_arg_from_edge (phi, g->e);
	  if (pi == -1)
	    abort();
	  Ti = PHI_ARG_DEF (phi, pi);
	}

      /* If this argument is a constant, or a SSA_NAME which is being
	 left in SSA form, just queue a copy to be emitted on this
	 edge.  */
      if (!phi_ssa_name_p (Ti)
	  || (TREE_CODE (Ti) == SSA_NAME
	      && var_to_partition (g->map, Ti) == NO_PARTITION))
        {
	  /* Save constant copies until all other copies have been emitted
	     on this edge.  */
	  VARRAY_PUSH_TREE (g->const_copies, T0);
	  VARRAY_PUSH_TREE (g->const_copies, Ti);
	}
      else
        {
	  Ti = var_to_partition_to_var (g->map, Ti);
	  if (T0 != Ti)
	    {
	      eliminate_name (g, T0);
	      eliminate_name (g, Ti);
	      p0 = var_to_partition (g->map, T0);
	      pi = var_to_partition (g->map, Ti);
	      elim_graph_add_edge (g, p0, pi);
	    }
	}
    }
}

/* Push successors onto the stack depth first.  */

static void 
elim_forward (elim_graph g, int T)
{
  int S;
  SET_BIT (g->visited, T);
  FOR_EACH_ELIM_GRAPH_SUCC (g, T, S,
    {
      if (!TEST_BIT (g->visited, S))
        elim_forward (g, S);
    });
  VARRAY_PUSH_INT (g->stack, T);
}


/* Are there unvisited predecessors?  */

static int
elim_unvisited_predecessor (elim_graph g, int T)
{
  int P;
  FOR_EACH_ELIM_GRAPH_PRED (g, T, P, 
    {
      if (!TEST_BIT (g->visited, P))
        return 1;
    });
  return 0;
}

/* Process predecessors first, and insert a copy.  */

static void
elim_backward (elim_graph g, int T)
{
  int P;
  SET_BIT (g->visited, T);
  FOR_EACH_ELIM_GRAPH_PRED (g, T, P, 
    {
      if (!TEST_BIT (g->visited, P))
        {
	  elim_backward (g, P);
	  insert_copy_on_edge (g->e, 
			       partition_to_var (g->map, P), 
			       partition_to_var (g->map, T));
	}
    });
}

/* Check for a SCR, and create a temporary if there is one, and break
   the cycle. Then issue the copies. Otherwise, simply insert the
   required copies.  */

static void 
elim_create (elim_graph g, int T)
{
  tree U;
  int P, S;

  if (elim_unvisited_predecessor (g, T))
    {
      U = create_temp (partition_to_var (g->map, T));
      insert_copy_on_edge (g->e, U, partition_to_var (g->map, T));
      FOR_EACH_ELIM_GRAPH_PRED (g, T, P, 
	{
	  if (!TEST_BIT (g->visited, P))
	    {
	      elim_backward (g, P);
	      insert_copy_on_edge (g->e, partition_to_var (g->map, P), U);
	    }
	});
    }
  else
    {
      S = elim_graph_remove_succ_edge (g, T);
      if (S != -1)
	{
	  SET_BIT (g->visited, T);
	  insert_copy_on_edge (g->e, 
			       partition_to_var (g->map, T), 
			       partition_to_var (g->map, S));
	}
    }
  
}

/* Eliminate all the phi nodes on this edge.  */

static void
eliminate_phi (edge e, int i, elim_graph g)
{
  int num_nodes = 0;
  int x;
  basic_block B = e->dest;

#if defined ENABLE_CHECKING
  if (i == -1)
    abort ();
  if (VARRAY_ACTIVE_SIZE (g->const_copies) != 0)
    abort ();
#endif

  /* Abnormal edges already have everything coalesced, or the coalescer
     would have aborted.  */
  if (e->flags & EDGE_ABNORMAL)
    return;

  num_nodes = num_var_partitions (g->map);
  g->e = e;

  eliminate_build (g, B, i);

  if (elim_graph_size (g) != 0)
    {
      sbitmap_zero (g->visited);
      VARRAY_POP_ALL (g->stack);

      for (x = 0; x < elim_graph_size (g); x++)
        {
	  tree var = VARRAY_TREE (g->nodes, x);
	  int p = var_to_partition (g->map, var);
	  if (!TEST_BIT (g->visited, p))
	    elim_forward (g, p);
	}
       
      sbitmap_zero (g->visited);
      while (VARRAY_ACTIVE_SIZE (g->stack) > 0)
	{
	  x = VARRAY_TOP_INT (g->stack);
	  VARRAY_POP (g->stack);
	  if (!TEST_BIT (g->visited, x))
	    elim_create (g, x);
	}
    }

  /* If there are any pending constant copies, issue them now.  */
  while (VARRAY_ACTIVE_SIZE (g->const_copies) > 0)
    {
      tree src, dest;
      src = VARRAY_TOP_TREE (g->const_copies);
      VARRAY_POP (g->const_copies);
      dest = VARRAY_TOP_TREE (g->const_copies);
      VARRAY_POP (g->const_copies);
      insert_copy_on_edge (e, dest, src);
    }
}


/* Shortcut routine to print messages of the form: "str expr str expr str."  */

static void
print_exprs (FILE *f, const char *str1, tree expr1, const char *str2,
	     tree expr2, const char *str3)
{
  fprintf (f, "%s", str1);
  print_generic_expr (f, expr1, TDF_SLIM);
  fprintf (f, "%s", str2);
  print_generic_expr (f, expr2, TDF_SLIM);
  fprintf (f, "%s", str3);
}

static void
print_exprs_edge (FILE *f, edge e, const char *str1, tree expr1, 
		  const char *str2, tree expr2)
{
  print_exprs (f, str1, expr1, str2, expr2, " across an abnormal edge");
  fprintf (f, " from BB%d->BB%d\n", e->src->index,
	       e->dest->index);
}

/* Coalesce partitions which are live across abnormal edges. Since code 
   cannot be inserted on these edges, failure to coalesce something across
   an abnormal edge is a non-compilable situation.  */

static void
coalesce_abnormal_edges (var_map map, conflict_graph graph, root_var_p rv)
{
  basic_block bb;
  edge e;
  tree phi, var, tmp;
  int x, y;

  /* Code cannot be inserted on abnormal edges. Look for all abnormal 
     edges, and coalesce any PHI results with their arguments across 
     that edge.  */

  FOR_EACH_BB (bb)
    for (e = bb->succ; e; e = e->succ_next)
      if (e->dest != EXIT_BLOCK_PTR && e->flags & EDGE_ABNORMAL)
	for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
	  {
	    /* Visit each PHI on the destination side of this abnormal
	       edge, and attempt to coalesce the argument with the result.  */
	    var = PHI_RESULT (phi);
	    x = var_to_partition (map, var);

	    /* Ignore results which are not relevant.  */
	    if (x == NO_PARTITION)
	      continue;

	    y = phi_arg_from_edge (phi, e);
	    if (y == -1)
	      abort ();

	    tmp = PHI_ARG_DEF (phi, y);
	    if (!phi_ssa_name_p (tmp))
	      {
	        print_exprs_edge (stderr, e,
				  "\nConstant argument in PHI. Can't insert :",
				  var, " = ", tmp);
		abort ();
	      }
	    y = var_to_partition (map, tmp);
	    if (x == NO_PARTITION || y == NO_PARTITION)
	      abort ();
	    if (root_var_find (rv, x) != root_var_find (rv, y))
	      {
		print_exprs_edge (stderr, e, "\nDifferent root vars: ",
				  root_var (rv, root_var_find (rv, x)), 
				  " and ", root_var (rv, root_var_find (rv, y)));
		abort ();
	      }

	    if (x != y)
	      {
		if (!conflict_graph_conflict_p (graph, x, y))
		  {
		    /* Now map the partitions back to their real variables.  */
		    var = partition_to_var (map, x);
		    tmp = partition_to_var (map, y);
		    if (dump_file 
			&& (dump_flags & TDF_DETAILS))
		      {
			print_exprs_edge (dump_file, e, "ABNORMAL: Coalescing ",
					  var, " and ", tmp);
		      }
		    if (var_union (map, var, tmp) == NO_PARTITION)
		      {
			print_exprs_edge (stderr, e, "\nUnable to coalesce", 
					  partition_to_var (map, x), " and ", 
					  partition_to_var (map, y));
			abort ();
		      }
		    conflict_graph_merge_regs (graph, x, y);
		  }
		else
		  {
		    print_exprs_edge (stderr, e, "\n Conflict ", 
				      partition_to_var (map, x),
				      " and ", partition_to_var (map, y));
		    abort ();
		  }
	      }
	  }
}


/* Reduce the number of live ranges in the var_map. The only partitions
   which are associated with actual variables at this point are those which 
   are forced to be coalesced for various reason. (live on entry, live 
   across abnormal edges, etc.). 
   Live range information is returned if FLAGS indicates that we are
   combining temporaries, otherwise NULL is returned.  */

static tree_live_info_p
coalesce_ssa_name (var_map map, int flags)
{
  int num, x, i;
  sbitmap live;
  tree var, phi;
  root_var_p rv;
  tree_live_info_p liveinfo;
  var_ann_t ann;
  conflict_graph graph;
  basic_block bb;
  coalesce_list_p cl = NULL;

  if (num_var_partitions (map) <= 1)
    return NULL;

  /* If no preference given, use cheap coalescing of all partitions.  */
  if ((flags & (SSANORM_COALESCE_PARTITIONS | SSANORM_USE_COALESCE_LIST)) == 0)
    flags |= SSANORM_COALESCE_PARTITIONS;
  
  liveinfo = calculate_live_on_entry (map);
  calculate_live_on_exit (liveinfo);
  rv = root_var_init (map);

  /* Remove single element variable from the list.  */
  root_var_compact (rv);

  if (flags & SSANORM_USE_COALESCE_LIST)
    {
      cl = create_coalesce_list (map);
      
      /* Add all potential copies via PHI arguments to the list.  */
      FOR_EACH_BB (bb)
	{
	  for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
	    {
	      tree res = PHI_RESULT (phi);
	      int p = var_to_partition (map, res);
	      if (p == NO_PARTITION)
		continue;
	      for (x = 0; x < PHI_NUM_ARGS (phi); x++)
		{
		  tree arg = PHI_ARG_DEF (phi, x);
		  int p2;

		  if (TREE_CODE (arg) != SSA_NAME)
		    continue;
		  if (SSA_NAME_VAR (res) != SSA_NAME_VAR (arg))
		    continue;
		  p2 = var_to_partition (map, PHI_ARG_DEF (phi, x));
		  if (p2 != NO_PARTITION)
		    add_coalesce (cl, p, p2, 1);
		}
	    }
	}

      /* Coalesce all the result decls together.  */
      var = NULL_TREE;
      i = 0;
      for (x = 0; x < num_var_partitions (map); x++)
	{
	  tree p = partition_to_var (map, x);
	  if (TREE_CODE (SSA_NAME_VAR(p)) == RESULT_DECL)
	    {
	      if (var == NULL_TREE)
		{
		  var = p;
		  i = x;
		}
	      else
		add_coalesce (cl, i, x, 1);
	    }
	}
    }

  /* Build a conflict graph.  */
  graph = build_tree_conflict_graph (liveinfo, rv, cl);

  if (cl)
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	{
	  fprintf (dump_file, "Before sorting:\n");
	  dump_coalesce_list (dump_file, cl);
	}

      sort_coalesce_list (cl);

      if (dump_file && (dump_flags & TDF_DETAILS))
	{
	  fprintf (dump_file, "\nAfter sorting:\n");
	  dump_coalesce_list (dump_file, cl);
	}
    }

  /* Put the single element variables back in.  */
  root_var_decompact (rv);

  /* First, coalesce all live on entry variables to their root variable. 
     This will ensure the first use is coming from the correct location. */

  live = sbitmap_alloc (num_var_partitions (map));
  sbitmap_zero (live);

  /* Set 'live' vector to indicate live on entry partitions.  */
  num = num_var_partitions (map);
  for (x = 0 ; x < num; x++)
    {
      var = partition_to_var (map, x);
      if (default_def (SSA_NAME_VAR (var)) == var)
	SET_BIT (live, x);
    }

  if ((flags & SSANORM_COMBINE_TEMPS) == 0)
    {
      delete_tree_live_info (liveinfo);
      liveinfo = NULL;
    }

  /* Assign root variable as partition representative for each live on entry
     partition.  */
  EXECUTE_IF_SET_IN_SBITMAP (live, 0, x, 
    {
      var = root_var (rv, root_var_find (rv, x));
      ann = var_ann (var);
      /* If these aren't already coalesced...  */
      if (partition_to_var (map, x) != var)
	{
	  if (ann->out_of_ssa_tag)
	    {
	      /* This root variable has already been assigned to another
		 partition which is not coalesced with this one.  */
	      abort ();
	    }

	  if (dump_file && (dump_flags & TDF_DETAILS))
	    {
	      print_exprs (dump_file, "Must coalesce ", 
			   partition_to_var (map, x),
			   " with the root variable ", var, ".\n");
	    }

	  change_partition_var (map, var, x);
	}
    });

  sbitmap_free (live);

  /* Coalesce partitions live across abnormal edges.  */
  coalesce_abnormal_edges (map, graph, rv);

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      dump_var_map (dump_file, map);
    }

  /* Coalesce partitions.  */
  if (flags & SSANORM_USE_COALESCE_LIST)
    coalesce_tpa_members (rv, graph, map, cl, 
			  ((dump_flags & TDF_DETAILS) ? dump_file 
							   : NULL));

  
  if (flags & SSANORM_COALESCE_PARTITIONS)
    coalesce_tpa_members (rv, graph, map, NULL, 
			  ((dump_flags & TDF_DETAILS) ? dump_file 
							   : NULL));
  if (cl)
    delete_coalesce_list (cl);
  root_var_delete (rv);
  conflict_graph_delete (graph);

  return liveinfo;
}

/* Take the ssa-name var_map, and assign real variables to each partition.  */

static void
assign_vars (var_map map)
{
  int x, i, num, rep;
  tree t, var;
  var_ann_t ann;
  root_var_p rv;

  rv = root_var_init (map);
  if (!rv) 
    return;

  /* Coalescing may already have forced some partitions to their root 
     variable. Find these and tag them.  */

  num = num_var_partitions (map);
  for (x = 0; x < num; x++)
    {
      var = partition_to_var (map, x);
      if (TREE_CODE (var) != SSA_NAME)
	{
	  /* Coalescing will already have verified that more than one
	     partition doesn't have the same root variable. Simply marked
	     the variable as assigned.  */
	  ann = var_ann (var);
	  ann->out_of_ssa_tag = 1;
	  if (dump_file && (dump_flags & TDF_DETAILS))
	    {
	      fprintf (dump_file, "partition %d has variable ", x);
	      print_generic_expr (dump_file, var, TDF_SLIM);
	      fprintf (dump_file, " assigned to it.\n");
	    }

	}
    }

  num = root_var_num (rv);
  for (x = 0; x < num; x++)
    {
      var = root_var (rv, x);
      ann = var_ann (var);
      for (i = root_var_first_partition (rv, x);
	   i != ROOT_VAR_NONE;
	   i = root_var_next_partition (rv, i))
	{
	  t = partition_to_var (map, i);

	  if (t == var || TREE_CODE (t) != SSA_NAME)
	    continue;

	  rep = var_to_partition (map, t);
	  
	  if (!ann->out_of_ssa_tag)
	    {
	      if (dump_file && (dump_flags & TDF_DETAILS))
		print_exprs (dump_file, "", t, "  --> ", var, "\n");
	      change_partition_var (map, var, rep);
	      continue;
	    }

	  if (dump_file && (dump_flags & TDF_DETAILS))
	    print_exprs (dump_file, "", t, " not coalesced with ", var, 
			 "");

	  var = create_temp (t);
	  change_partition_var (map, var, rep);
	  ann = var_ann (var);

	  if (dump_file && (dump_flags & TDF_DETAILS))
	    {
	      fprintf (dump_file, " -->  New temp:  '");
	      print_generic_expr (dump_file, var, TDF_SLIM);
	      fprintf (dump_file, "'\n");
	    }
	}
    }

  root_var_delete (rv);
}

/* Replace *p with whatever variable it has been rewritten to.  If it changes
   the stmt, return true.  */

static inline bool
replace_variable (var_map map, tree *p, tree *expr)
{
  tree new_var;
  tree var = *p;

  /* Check if we are replacing this variable with an expression.  */
  if (expr)
    {
      int version = SSA_NAME_VERSION (*p);
      if (expr[version])
        {
	  tree new_expr = TREE_OPERAND (expr[version], 1);
	  *p = new_expr;
	  /* Clear the stmt's RHS, or GC might bite us.  */
	  TREE_OPERAND (expr[version], 1) = NULL_TREE;
	  return true;
	}
    }

  new_var = var_to_partition_to_var (map, var);
  if (new_var)
    {
      *p = new_var;
      set_is_used (new_var);
      return true;
    }
  return false;
}


/* Remove any PHI node which is virtual PHI.  */
static void
eliminate_virtual_phis (void)
{
  basic_block bb;
  tree phi, next;

  FOR_EACH_BB (bb)
    {
      for (phi = phi_nodes (bb); phi; phi = next)
        {
	  next = TREE_CHAIN (phi);
	  if (!is_gimple_reg (SSA_NAME_VAR (PHI_RESULT (phi))))
	    {
#ifdef ENABLE_CHECKING
	      int i;
	      /* There should be no arguments of this PHI which are in
		 the partition list, or we get incorrect results.  */
	      for (i = 0; i < PHI_NUM_ARGS (phi); i++)
	        {
		  tree arg = PHI_ARG_DEF (phi, i);
		  if (TREE_CODE (arg) == SSA_NAME 
		      && is_gimple_reg (SSA_NAME_VAR (arg)))
		    {
		      fprintf (stderr, "Argument of PHI is not virtual (");
		      print_generic_expr (stderr, arg, TDF_SLIM);
		      fprintf (stderr, "), but the result is :");
		      print_generic_stmt (stderr, phi, TDF_SLIM);
		      abort();
		    }
		}
#endif
	      remove_phi_node (phi, NULL_TREE, bb);
	    }
	}
    }
}


/* This routine will coalesce variables of the same type which do not 
   interfere with each other. This will both reduce the memory footprint of
   the stack, and allow us to coalesce together local copies of globals and
   scalarized component refs.  */

static void
coalesce_vars (var_map map, tree_live_info_p liveinfo)
{
  basic_block bb;
  type_var_p tv;
  tree var;
  int x, p, p2;
  coalesce_list_p cl;
  conflict_graph graph;

  cl = create_coalesce_list (map);

  /* Merge all the live on entry vectors for coalesced partitions.  */
  for (x = 0; x < num_var_partitions (map); x++)
    {
      var = partition_to_var (map, x);
      p = var_to_partition (map, var);
      if (p != x)
        live_merge_and_clear (liveinfo, p, x);
    }

  /* When PHI nodes are turned into copies, the result of each PHI node
     becomes live on entry to the block. Mark these now.  */
  FOR_EACH_BB (bb)
    {
      tree phi, arg;
      int p;
      for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
	{
	  p = var_to_partition (map, PHI_RESULT (phi));

	  /* Skip virtual PHI nodes.  */
	  if (p == NO_PARTITION)
	    continue;

	  make_live_on_entry (liveinfo, bb, p);

	  /* Each argument is a potential copy operation. Add any arguments 
	     which are not coalesced to the result to the coalesce list.  */
	  for (x = 0; x < PHI_NUM_ARGS (phi); x++)
	    {
	      arg = PHI_ARG_DEF (phi, x);
	      if (!phi_ssa_name_p (arg))
	        continue;
	      p2 = var_to_partition (map, arg);
	      if (p2 == NO_PARTITION)
		continue;
	      if (p != p2)
	        add_coalesce (cl, p, p2, 1);
	    }
	}
   }

  
  /* Re-calculate live on exit info.  */
  calculate_live_on_exit (liveinfo);

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Live range info for variable memory coalescing.\n");
      dump_live_info (dump_file, liveinfo, LIVEDUMP_ALL);

      fprintf (dump_file, "Coalesce list from phi nodes:\n");
      dump_coalesce_list (dump_file, cl);
    }


  tv = type_var_init (map);
  if (dump_file)
    type_var_dump (dump_file, tv);
  type_var_compact (tv);
  if (dump_file)
    type_var_dump (dump_file, tv);

  graph = build_tree_conflict_graph (liveinfo, tv, cl);

  type_var_decompact (tv);
  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "type var list now looks like:n");
      type_var_dump (dump_file, tv);

      fprintf (dump_file, "Coalesce list after conflict graph build:\n");
      dump_coalesce_list (dump_file, cl);
    }

  sort_coalesce_list (cl);
  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Coalesce list after sorting:\n");
      dump_coalesce_list (dump_file, cl);
    }

  coalesce_tpa_members (tv, graph, map, cl, 
			((dump_flags & TDF_DETAILS) ? dump_file : NULL));

  type_var_delete (tv);
  delete_coalesce_list (cl);
}


/* Temporary Expression Replacement (TER)

   Replace SSA version variables during out-of-ssa with their defining
   expression if there is only one use of the variable.

   A pass is made through the function, one block at a time. No cross block
   information is tracked.

   Variables which only have one use, and whose defining stmt is considered
   a replaceable expression (see check_replaceable) are entered into 
   consideration by adding a list of dependent partitions to the version_info
   vector for that ssa_name_version. This information comes from the partition
   mapping for each USE. At the same time, the partition_dep_list vector for 
   these partitions have this version number entered into their lists.

   When the use of a replaceable ssa_variable is encountered, the dependence
   list in version_info[] is moved to the "pending_dependence" list in case
   the current expression is also replaceable. (To be determined later in 
   processing this stmt.) version_info[] for the version is then updated to 
   point to the defining stmt and the 'replaceable' bit is set.

   Any partition which is defined by a statement 'kills' any expression which
   is dependent on this partition. Every ssa version in the partitions' 
   dependence list is removed from future consideration.

   All virtual references are lumped together. Any expression which is
   dependent on any virtual variable (via a VUSE) has a dependence added
   to the special partition defined by VIRTUAL_PARTITION.

   Whenever a VDEF is seen, all expressions dependent this VIRTUAL_PARTITION
   are removed from consideration.

   At the end of a basic block, all expression are removed from consideration
   in preparation for the next block.  
   
   The end result is a vector over SSA_NAME_VERSION which is passed back to
   rewrite_out_of_ssa.  As the SSA variables are being rewritten, instead of
   replacing the SSA_NAME tree element with the partition it was assigned, 
   it is replaced with the RHS of the defining expression.  */

/* Dependancy list element.  This can contain either a partition index or a
   version number, depending on which list it is in.  */
typedef struct value_expr_d 
{
  int value;
  struct value_expr_d *next;
} *value_expr_p;

/* Temporary Expression Replacement (TER) table information.  */
typedef struct temp_expr_table_d 
{
  var_map map;
  void **version_info;		
  value_expr_p *partition_dep_list;
  bitmap replaceable;
  bool saw_replaceable;
  int virtual_partition;
  bitmap partition_in_use;
  value_expr_p free_list;
  value_expr_p pending_dependence;
} *temp_expr_table_p;

/* Used to indicate a dependancy on VDEFs.  */
#define VIRTUAL_PARTITION(table)	(table->virtual_partition)

static temp_expr_table_p new_temp_expr_table (var_map);
static tree *free_temp_expr_table (temp_expr_table_p);
static inline value_expr_p new_value_expr (temp_expr_table_p);
static inline void free_value_expr (temp_expr_table_p, value_expr_p);
static inline value_expr_p find_value_in_list (value_expr_p, int, 
					       value_expr_p *);
static inline void add_value_to_list (temp_expr_table_p, value_expr_p *, int);
static inline void add_info_to_list (temp_expr_table_p, value_expr_p *, 
				     value_expr_p);
static value_expr_p remove_value_from_list (value_expr_p *, int);
static void add_dependance (temp_expr_table_p, int, tree);
static bool check_replaceable (temp_expr_table_p, tree);
static void finish_expr (temp_expr_table_p, int, bool);
static void mark_replaceable (temp_expr_table_p, tree);
static inline void kill_expr (temp_expr_table_p, int, bool);
static inline void kill_virtual_exprs (temp_expr_table_p, bool);
static void find_replaceable_in_bb (temp_expr_table_p, basic_block);
static tree *find_replaceable_exprs (var_map);
static void dump_replaceable_exprs (FILE *, tree *);

/* Create a new TER table.  */
static temp_expr_table_p
new_temp_expr_table (var_map map)
{
  temp_expr_table_p t;

  t = (temp_expr_table_p) xmalloc (sizeof (struct temp_expr_table_d));
  t->map = map;

  t->version_info = xcalloc (highest_ssa_version + 1, sizeof (void *));
  t->partition_dep_list = xcalloc (num_var_partitions (map) + 1, 
				   sizeof (value_expr_p));

  t->replaceable = BITMAP_XMALLOC ();
  t->partition_in_use = BITMAP_XMALLOC ();

  t->saw_replaceable = false;
  t->virtual_partition = num_var_partitions (map);
  t->free_list = NULL;
  t->pending_dependence = NULL;

  return t;
}


/* Free a TER table.  If there are valid replacements, return the expression 
   vector.  */
static tree *
free_temp_expr_table (temp_expr_table_p t)
{
  value_expr_p p;
  tree *ret = NULL;

#ifdef ENABLE_CHECKING
  int x;
  for (x = 0; x <= num_var_partitions (t->map); x++)
    if (t->partition_dep_list[x] != NULL)
      abort();
#endif

  while ((p = t->free_list))
    {
      t->free_list = p->next;
      free (p);
    }

  BITMAP_XFREE (t->partition_in_use);
  BITMAP_XFREE (t->replaceable);

  free (t->partition_dep_list);
  if (t->saw_replaceable)
    ret = (tree *)t->version_info;
  else
    free (t->version_info);
  
  free (t);
  return ret;
}


/* Allocate a new value list node. Take it from the free list if possible.  */
static inline value_expr_p
new_value_expr (temp_expr_table_p table)
{
  value_expr_p p;
  if (table->free_list)
    {
      p = table->free_list;
      table->free_list = p->next;
    }
  else
    p = (value_expr_p) xmalloc (sizeof (struct value_expr_d));

  return p;
}


/* Add a value list node to the free list.  */
static inline void
free_value_expr (temp_expr_table_p table, value_expr_p p)
{
  p->next = table->free_list;
  table->free_list = p;
}


/* Find a specific value if its in a list.  Return a pointer to the list 
   object if found.  Return NULL if it isn't.  If last_ptr is provided,
   it will point to the previous item upon return, or NULL if this is the 
   first item in the list.  */
static inline value_expr_p
find_value_in_list (value_expr_p list, int value, value_expr_p *last_ptr)
{
  value_expr_p curr;
  value_expr_p last = NULL;

  for (curr = list; curr; last = curr, curr = curr->next)
    {
      if (curr->value == value)
        break;
    }
  if (last_ptr)
    *last_ptr = last;
  return curr;
}


/* Add a value to a list, if it isn't already present.  */
static inline void
add_value_to_list (temp_expr_table_p tab, value_expr_p *list, int value)
{
  value_expr_p info;

  if (!find_value_in_list (*list, value, NULL))
    {
      info = new_value_expr (tab);
      info->value = value;
      info->next = *list;
      *list = info;
    }
}


/* Add a value node if it's value isn't already in the list.  Free this node if
   it is already in the list.  */
static inline void
add_info_to_list (temp_expr_table_p tab, value_expr_p *list, value_expr_p info)
{
  if (find_value_in_list (*list, info->value, NULL))
    free_value_expr (tab, info);
  else
    {
      info->next = *list;
      *list = info;
    }
}


/* Look for a value in a list.  If found, remove it from the list and return 
   it's pointer.  */
static value_expr_p
remove_value_from_list (value_expr_p *list, int value)
{
  value_expr_p info, last;

  info = find_value_in_list (*list, value, &last);
  if (!info)
    return NULL;
  if (!last)
    *list = info->next;
  else
    last->next = info->next;
 
  return info;
}


/* Add a dependancy between the def of an SSA version and the partitions each
   use in the expression represent.  */
static void
add_dependance (temp_expr_table_p tab, int version, tree var)
{
  int i, x;
  value_expr_p info;

  i = SSA_NAME_VERSION (var);
  if (bitmap_bit_p (tab->replaceable, i))
    {
      /* This variable is being substituted, so use whatever dependences
         were queued up when we marked this as replaceable earlier.  */
      while ((info = tab->pending_dependence))
        {
	  tab->pending_dependence = info->next;
	  /* Get the partition this variable was dependent on. Reuse this
	     object to represent the current  expression instead.  */
	  x = info->value;
	  info->value = version;
	  add_info_to_list (tab, &(tab->partition_dep_list[x]), info);
          add_value_to_list (tab, 
			     (value_expr_p *)&(tab->version_info[version]), x);
	  bitmap_set_bit (tab->partition_in_use, x);
	}
    }
  else
    {
      i = var_to_partition (tab->map, var);
#ifdef ENABLE_CHECKING
      if (i== NO_PARTITION)
	abort ();
#endif
      add_value_to_list (tab, &(tab->partition_dep_list[i]), version);
      add_value_to_list (tab, (value_expr_p *)&(tab->version_info[version]), i);
      bitmap_set_bit (tab->partition_in_use, i);
    }
}


/* Check if an expression is suitable for replacement.  If so, create an 
   expression entry.  Return true if this stmt is replaceable.  */

static bool
check_replaceable (temp_expr_table_p tab, tree stmt)
{
  stmt_ann_t ann;
  vuse_optype vuseops;
  def_optype defs;
  use_optype uses;
  tree var, def;
  int num_use_ops, version, i;
  var_map map = tab->map;

  if (TREE_CODE (stmt) != MODIFY_EXPR)
    return false;
  
  ann = stmt_ann (stmt);
  defs = DEF_OPS (ann);

  /* Punt if there is more than 1 def, or more than 1 use.  */
  if (NUM_DEFS (defs) != 1)
    return false;
  def = DEF_OP (defs, 0);
  if (version_ref_count (map, def) != 1)
    return false;

  /* Assignments to variables assigned to hard registers are not
     replaceable.  */
  if (DECL_HARD_REGISTER (SSA_NAME_VAR (def)))
    return false;

  /* There must be no VDEFS.  */
  if (NUM_VDEFS (VDEF_OPS (ann)) != 0)
    return false;

  /* Float expressions must go through memory if float-store is on.  */
  if (flag_float_store && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (stmt, 1))))
    return false;

  uses = USE_OPS (ann);
  num_use_ops = NUM_USES (uses);
  vuseops = VUSE_OPS (ann);

  /* Any expression which has no virtual operands and no real operands
     should have been propagated if it's possible to do anything with them. 
     If this happens here, it probably exists that way for a reason, so we 
     won't touch it.   An example is:
         b_4 = &tab
     There are no virtual uses nor any real uses, so we just leave this 
     alone to be safe.  */

  if (num_use_ops == 0 && NUM_VUSES (vuseops) == 0)
    return false;

  version = SSA_NAME_VERSION (def);

  /* Add this expression to the dependancy list for each use partition.  */
  for (i = 0; i < num_use_ops; i++)
    {
      var = USE_OP (uses, i);
      add_dependance (tab, version, var);
    }

  /* If there are VUSES, add a dependence on virtual defs.  */
  if (NUM_VUSES (vuseops) != 0)
    {
      add_value_to_list (tab, (value_expr_p *)&(tab->version_info[version]), 
			 VIRTUAL_PARTITION (tab));
      add_value_to_list (tab, 
			 &(tab->partition_dep_list[VIRTUAL_PARTITION (tab)]), 
			 version);
      bitmap_set_bit (tab->partition_in_use, VIRTUAL_PARTITION (tab));
    }

  return true;
}


/* This function will remove an expression from replacement consideration.  If
   'replace' is true, it is marked as replaceable, otherwise not.  */
static void
finish_expr (temp_expr_table_p tab, int version, bool replace)
{
  value_expr_p info, tmp;
  int partition;

  /* Remove this expression from its dependent lists.  The partition dependance
     list is retained and transfered later to whomever uses this version.  */
  for (info = (value_expr_p) tab->version_info[version]; info; info = tmp)
    {
      partition = info->value;
#ifdef ENABLE_CHECKING
      if (tab->partition_dep_list[partition] == NULL)
        abort ();
#endif
      tmp = remove_value_from_list (&(tab->partition_dep_list[partition]), 
				    version);
#ifdef ENABLE_CHECKING
      if (!tmp)
        abort ();
#endif
      free_value_expr (tab, tmp);
      /* Only clear the bit when the dependancy list is emptied via 
         a replacement. Otherwise kill_expr will take care of it.  */
      if (!(tab->partition_dep_list[partition]) && replace)
        bitmap_clear_bit (tab->partition_in_use, partition);
      tmp = info->next;
      if (!replace)
        free_value_expr (tab, info);
    }

  if (replace)
    {
      tab->saw_replaceable = true;
      bitmap_set_bit (tab->replaceable, version);
    }
  else
    {
#ifdef ENABLE_CHECKING
      if (bitmap_bit_p (tab->replaceable, version))
	abort ();
#endif
      tab->version_info[version] = NULL;
    }
}


/* Mark the expression associated with a variable as replaceable, and enter
   the defining stmt into the version_info table.  */
static void
mark_replaceable (temp_expr_table_p tab, tree var)
{
  value_expr_p info;
  int version = SSA_NAME_VERSION (var);
  finish_expr (tab, version, true);

  /* Move the dependence list to the pending list.  */
  if (tab->version_info[version])
    {
      info = (value_expr_p) tab->version_info[version]; 
      for ( ; info->next; info = info->next)
	continue;
      info->next = tab->pending_dependence;
      tab->pending_dependence = (value_expr_p)tab->version_info[version];
    }

  tab->version_info[version] = SSA_NAME_DEF_STMT (var);
}


/* This function finishes any expression which is dependent on this partition
   as NOT replaceable.  clear_bit is used to determine whether partition_in_use
   should have iuts bit cleared. Since this can be called within an
   EXECUTE_IF_SET_IN_BITMAP, the bit can't always be cleared.  */
static inline void
kill_expr (temp_expr_table_p tab, int partition, bool clear_bit)
{
  value_expr_p ptr;

  /* Mark every active expr dependant on this var as not replaceable.  */
  while ((ptr = tab->partition_dep_list[partition]) != NULL)
    finish_expr (tab, ptr->value, false);

  if (clear_bit)
    bitmap_clear_bit (tab->partition_in_use, partition);
}


/* This function kills all expressions which are dependant on virtual DEFs.  */
static inline void
kill_virtual_exprs (temp_expr_table_p tab, bool clear_bit)
{
  kill_expr (tab, VIRTUAL_PARTITION (tab), clear_bit);
}


/* This function processes a basic block, and looks for variables which can
   be replaced by their expressions.  */
static void
find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb)
{
  block_stmt_iterator bsi;
  tree stmt, def;
  stmt_ann_t ann;
  int partition, num, i;
  use_optype uses;
  def_optype defs;
  var_map map = tab->map;
  value_expr_p p;

  for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
    {
      stmt = bsi_stmt (bsi);
      ann = stmt_ann (stmt);

      /* Determine if this stmt finishes an existing expression.  */
      uses = USE_OPS (ann);
      num = NUM_USES (uses);
      for (i = 0; i < num; i++)
	{
	  def = USE_OP (uses, i);
	  if (tab->version_info[SSA_NAME_VERSION (def)])
	    {
	      /* Mark expression as replaceable unless stmt is volatile.  */
	      if (!ann->has_volatile_ops)
		mark_replaceable (tab, def);
	      else
		finish_expr (tab, SSA_NAME_VERSION (def), false);
	    }
	}
      
      /* Next, see if this stmt kills off an active expression.  */
      defs = DEF_OPS (ann);
      num = NUM_DEFS (defs);
      for (i = 0; i < num; i++)
	{
	  def = DEF_OP (defs, i);
	  partition = var_to_partition (map, def);
	  if (partition != NO_PARTITION && tab->partition_dep_list[partition])
	    kill_expr (tab, partition, true);
	}

      /* Now see if we are creating a new expression or not.  */
      if (!ann->has_volatile_ops)
	check_replaceable (tab, stmt);

      /* Free any unused dependancy lists.  */
      while ((p = tab->pending_dependence))
	{
	  tab->pending_dependence = p->next;
	  free_value_expr (tab, p);
	}

      /* A VDEF kills any expression using a virtual operand.  */
      if (NUM_VDEFS (VDEF_OPS (ann)) > 0)
        kill_virtual_exprs (tab, true);
    }
}


/* This function is the driver routine for replacement of temporary expressions
   in the SSA->normal phase.  If there are replaceable expressions, a table is 
   returned which maps SSA versions to the expressions they should be replaced 
   with.  A NULL_TREE indicates no replacement should take place.  
   If there are no replacements at all, NULL is returned by the function.  */
static tree *
find_replaceable_exprs (var_map map)
{
  basic_block bb;
  int i;
  temp_expr_table_p table;
  tree *ret;

  table = new_temp_expr_table (map);
  FOR_EACH_BB (bb)
    {
      find_replaceable_in_bb (table, bb);
      EXECUTE_IF_SET_IN_BITMAP ((table->partition_in_use), 0, i,
        {
	  kill_expr (table, i, false);
	});
    }

  ret = free_temp_expr_table (table);
  return ret;
}


/* Dump the TER expression table.  */
static void
dump_replaceable_exprs (FILE *f, tree *expr)
{
  tree stmt, var;
  int x;
  fprintf (f, "\nReplacing Expressions\n");
  for (x = 0; x < (int)highest_ssa_version + 1; x++)
    if (expr[x])
      {
        stmt = expr[x];
	var = DEF_OP (STMT_DEF_OPS (stmt), 0);
	print_generic_expr (f, var, TDF_SLIM);
	fprintf (f, " replace with --> ");
	print_generic_expr (f, TREE_OPERAND (stmt, 1), TDF_SLIM);
	fprintf (f, "\n");
      }
  fprintf (f, "\n");
}


/* This function will rewrite the current program using the variable mapping
   found in 'map'. If the replacement vector 'values' is provided, any 
   occurrences of partitions with non-null entries in the vector will be 
   replaced with the expression in the vector instead of its mapped 
   variable.  */

static void
rewrite_trees (var_map map, tree *values)
{
  elim_graph g;
  basic_block bb;
  block_stmt_iterator si;
  edge e;
  tree phi;
  bool changed;

  /* Replace PHI nodes with any required copies.  */
  g = new_elim_graph (map->num_partitions);
  g->map = map;
  FOR_EACH_BB (bb)
    {
      for (si = bsi_start (bb); !bsi_end_p (si); )
	{
	  size_t i, num_uses, num_defs;
	  use_optype uses;
	  def_optype defs;
	  tree stmt = bsi_stmt (si);
	  tree *use_p = NULL;
	  int remove = 0, is_copy = 0;
	  stmt_ann_t ann;

	  get_stmt_operands (stmt);
	  ann = stmt_ann (stmt);
	  changed = false;

	  if (TREE_CODE (stmt) == MODIFY_EXPR 
	      && (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME))
	    is_copy = 1;

	  uses = USE_OPS (ann);
	  num_uses = NUM_USES (uses);

	  for (i = 0; i < num_uses; i++)
	    {
	      use_p = USE_OP_PTR (uses, i);
	      if (replace_variable (map, use_p, values))
	        changed = true;
	    }

	  defs = DEF_OPS (ann);
	  num_defs = NUM_DEFS (defs);

	  if (values && num_defs == 1)
	    {
	      tree def = DEF_OP (defs, 0);
	      tree val;
	      val = values[SSA_NAME_VERSION (def)];
	      if (val)
		remove = 1;
	    }
	  if (!remove)
	    {
	      for (i = 0; i < num_defs; i++)
		{
		  tree *def_p = DEF_OP_PTR (defs, i);

		  if (replace_variable (map, def_p, NULL))
		    changed = true;

		  if (is_copy
		      && num_uses == 1
		      && use_p
		      && def_p
		      && (*def_p == *use_p))
		    remove = 1;
		}
	      if (changed)
		modify_stmt (stmt);
	    }

	  /* Remove copies of the form 'var = var'.  */
	  if (remove)
	    bsi_remove (&si);
	  else
	    bsi_next (&si);
	}

      phi = phi_nodes (bb);
      if (phi)
        {
	  for (e = bb->pred; e; e = e->pred_next)
	    eliminate_phi (e, phi_arg_from_edge (phi, e), g);
	}
    }

  delete_elim_graph (g);

  /* If any copies were inserted on edges, actually insert them now.  */
  bsi_commit_edge_inserts (NULL);
}

/* Remove the variables specified in a var map from SSA form.  */
void
remove_ssa_form (FILE *dump, var_map map, int flags)
{
  tree_live_info_p liveinfo;
  basic_block bb;
  tree phi, next;
  FILE *save;
  tree *values = NULL;

  save = dump_file;
  dump_file = dump;

  /* If we are not combining temps, dont calculate live ranges fo variables
     with only one SSA version.  */
  if ((flags & SSANORM_COMBINE_TEMPS) == 0)
    compact_var_map (map, VARMAP_NO_SINGLE_DEFS);
  else
    compact_var_map (map, VARMAP_NORMAL);

  if (dump_file && (dump_flags & TDF_DETAILS))
    dump_var_map (dump_file, map);

  liveinfo = coalesce_ssa_name (map, flags);

  /* Make sure even single occurrence variables are in the list now.  */
  if ((flags & SSANORM_COMBINE_TEMPS) == 0)
    compact_var_map (map, VARMAP_NORMAL);

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "After Coalescing:\n");
      dump_var_map (dump_file, map);
    }

  if (flags & SSANORM_PERFORM_TER)
    {
      values = find_replaceable_exprs (map);
      if (values && dump_file && (dump_flags & TDF_DETAILS))
	dump_replaceable_exprs (dump_file, values);
    }

  /* Assign real variables to the partitions now.  */
  assign_vars (map);

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "After Root variable replacement:\n");
      dump_var_map (dump_file, map);
    }

  if ((flags & SSANORM_COMBINE_TEMPS) && liveinfo)
    {
      coalesce_vars (map, liveinfo);
      if (dump_file && (dump_flags & TDF_DETAILS))
	{
	  fprintf (dump_file, "After variable memory coalescing:\n");
	  dump_var_map (dump_file, map);
	}
    }
  
  if (liveinfo)
    delete_tree_live_info (liveinfo);

  rewrite_trees (map, values);

  if (values)
    free (values);

  /* Remove phi nodes which have been translated back to real variables.  */
  FOR_EACH_BB (bb)
    {
      for (phi = phi_nodes (bb); phi; phi = next)
	{
	  next = TREE_CHAIN (phi);
	  if ((flags & SSANORM_REMOVE_ALL_PHIS) 
	      || var_to_partition (map, PHI_RESULT (phi)) != NO_PARTITION)
	    remove_phi_node (phi, NULL_TREE, bb);
	}
    }

  dump_file = save;
}

/* Take a subset of the variables (VARS) in the current function out of SSA
   form.  */

void
rewrite_vars_out_of_ssa (bitmap vars)
{
  if (bitmap_first_set_bit (vars) >= 0)
    {
      var_map map;
      basic_block bb;
      tree phi;
      int i;
      int ssa_flags;

      /* Search for PHIs in which one of the PHI arguments is marked for
	 translation out of SSA form, but for which the PHI result is not
	 marked for translation out of SSA form.

	 Our per-variable out of SSA translation can not handle that case;
	 however we can easily handle it here by creating a new instance
	 of the PHI result's underlying variable and initializing it to
	 the offending PHI argument on the edge associated with the
	 PHI argument.  We then change the PHI argument to use our new
	 instead of the PHI's underlying variable.

	 You might think we could register partitions for the out-of-ssa
	 translation here and avoid a second walk of the PHI nodes.  No
	 such luck since the size of the var map will change if we have
	 to manually take variables out of SSA form here.  */
      FOR_EACH_BB (bb)
	{
	  for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
	    {
	      tree result = SSA_NAME_VAR (PHI_RESULT (phi));

	      /* If the definition is marked for renaming, then we need
		 to do nothing more for this PHI node.  */
	      if (bitmap_bit_p (vars, var_ann (result)->uid))
		continue;

	      /* Look at all the arguments and see if any of them are
		 marked for renaming.  If so, we need to handle them
		 specially.  */
	      for (i = 0; i < PHI_NUM_ARGS (phi); i++)
		{
		  tree arg = PHI_ARG_DEF (phi, i);

		  /* If the argument is not an SSA_NAME, then we can ignore
		     this argument.  */
		  if (TREE_CODE (arg) != SSA_NAME)
		    continue;

		  /* If this argument is marked for renaming, then we need
		     to undo the copy propagation so that we can take
		     the argument out of SSA form without taking the
		     result out of SSA form.  */
		  arg = SSA_NAME_VAR (arg);
		  if (bitmap_bit_p (vars, var_ann (arg)->uid))
		    {
		      tree new_name, copy;

		      /* Get a new SSA_NAME for the copy, it is based on
			 the result, not the argument!   We use the PHI
			 as the definition since we haven't created the
			 definition statement yet.  */
		      new_name = make_ssa_name (result, phi);

		      /* Now create the copy statement.  */
		      copy = build (MODIFY_EXPR, TREE_TYPE (arg),
				    new_name, PHI_ARG_DEF (phi, i));

		      /* Now update SSA_NAME_DEF_STMT to point to the
			 newly created statement.  */
		      SSA_NAME_DEF_STMT (new_name) = copy;

		      /* Now make the argument reference our new SSA_NAME.  */
		      PHI_ARG_DEF (phi, i) = new_name;

		      /* Queue the statement for insertion.  */
		      bsi_insert_on_edge (PHI_ARG_EDGE (phi, i), copy);
		      modify_stmt (copy);
		    }
		}
	    }
	}

      /* If any copies were inserted on edges, actually insert them now.  */
      bsi_commit_edge_inserts (NULL);
                                                                                
      /* Now register partitions for all instances of the variables we
	 are taking out of SSA form.  */
      map = init_var_map (highest_ssa_version + 1);
      register_ssa_partitions_for_vars (vars, map);

      /* Now that we have all the partitions registered, translate the
	 appropriate variables out of SSA form.  */
      ssa_flags = SSANORM_COALESCE_PARTITIONS;
      if (flag_tree_combine_temps)
	ssa_flags |= SSANORM_COMBINE_TEMPS;
      remove_ssa_form (dump_file, map, ssa_flags);

      /* And finally, reset the out_of_ssa flag for each of the vars
	 we just took out of SSA form.  */
      EXECUTE_IF_SET_IN_BITMAP (vars, 0, i,
	{
	  var_ann (referenced_var (i))->out_of_ssa_tag = 0;
	});

    }
}


/* Take the current function out of SSA form, as described in
   R. Morgan, ``Building an Optimizing Compiler'',
   Butterworth-Heinemann, Boston, MA, 1998. pp 176-186.  */

static void
rewrite_out_of_ssa (void)
{
  var_map map;
  int var_flags = 0;
  int ssa_flags = (SSANORM_REMOVE_ALL_PHIS | SSANORM_USE_COALESCE_LIST
		   | SSANORM_COALESCE_PARTITIONS);

  eliminate_virtual_phis ();

  if (dump_file && (dump_flags & TDF_DETAILS))
    dump_tree_cfg (dump_file, dump_flags & ~TDF_DETAILS);

  /* We cannot allow unssa to un-gimplify trees before we instrument them.  */
  if (flag_tree_ter && !flag_mudflap)
    var_flags = SSA_VAR_MAP_REF_COUNT;

  map = create_ssa_var_map (var_flags);

  if (flag_tree_combine_temps)
    ssa_flags |= SSANORM_COMBINE_TEMPS;
  if (flag_tree_ter && !flag_mudflap)
    ssa_flags |= SSANORM_PERFORM_TER;

  remove_ssa_form (dump_file, map, ssa_flags);

  if (dump_file && (dump_flags & TDF_DETAILS))
    dump_tree_cfg (dump_file, dump_flags & ~TDF_DETAILS);

  /* Do some cleanups which reduce the amount of data the
     tree->rtl expanders deal with.  */
  cfg_remove_useless_stmts ();

  /* Flush out flow graph and SSA data.  */
  delete_var_map (map);

  /* Mark arrays indexed with non-constant indices with TREE_ADDRESSABLE.  */
  discover_nonconstant_array_refs ();
}


struct tree_opt_pass pass_del_ssa = 
{
  "optimized",				/* name */
  NULL,					/* gate */
  rewrite_out_of_ssa,			/* execute */
  NULL,					/* sub */
  NULL,					/* next */
  0,					/* static_pass_number */
  TV_TREE_SSA_TO_NORMAL,		/* tv_id */
  PROP_cfg | PROP_ssa,			/* properties_required */
  0,					/* properties_provided */
  /* ??? If TER is enabled, we also kill gimple.  */
  PROP_ssa,				/* properties_destroyed */
  TODO_verify_ssa | TODO_verify_flow
    | TODO_verify_stmts,		/* todo_flags_start */
  TODO_dump_func | TODO_ggc_collect	/* todo_flags_finish */
};