--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/ipa-reference.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,1286 @@
+/* Callgraph based analysis of static variables.
+   Copyright (C) 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
+   Contributed by Kenneth Zadeck <zadeck@naturalbridge.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 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/>.  */
+
+/* This file gathers information about how variables whose scope is
+   confined to the compilation unit are used.  
+
+   There are two categories of information produced by this pass:
+
+   1) The addressable (TREE_ADDRESSABLE) bit and readonly
+   (TREE_READONLY) bit associated with these variables is properly set
+   based on scanning all of the code withing the compilation unit.
+
+   2) The transitive call site specific clobber effects are computed
+   for the variables whose scope is contained within this compilation
+   unit.
+
+   First each function and static variable initialization is analyzed
+   to determine which local static variables are either read, written,
+   or have their address taken.  Any local static that has its address
+   taken is removed from consideration.  Once the local read and
+   writes are determined, a transitive closure of this information is
+   performed over the call graph to determine the worst case set of
+   side effects of each call.  In later parts of the compiler, these
+   local and global sets are examined to make the call clobbering less
+   traumatic, promote some statics to registers, and improve aliasing
+   information.
+   
+   Currently must be run after inlining decisions have been made since
+   otherwise, the local sets will not contain information that is
+   consistent with post inlined state.  The global sets are not prone
+   to this problem since they are by definition transitive.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "tree.h"
+#include "tree-flow.h"
+#include "tree-inline.h"
+#include "tree-pass.h"
+#include "langhooks.h"
+#include "pointer-set.h"
+#include "ggc.h"
+#include "ipa-utils.h"
+#include "ipa-reference.h"
+#include "c-common.h"
+#include "gimple.h"
+#include "cgraph.h"
+#include "output.h"
+#include "flags.h"
+#include "timevar.h"
+#include "diagnostic.h"
+#include "langhooks.h"
+
+/* The static variables defined within the compilation unit that are
+   loaded or stored directly by function that owns this structure.  */ 
+
+struct ipa_reference_local_vars_info_d 
+{
+  bitmap statics_read;
+  bitmap statics_written;
+
+  /* Set when this function calls another function external to the
+     compilation unit or if the function has a asm clobber of memory.
+     In general, such calls are modeled as reading and writing all
+     variables (both bits on) but sometime there are attributes on the
+     called function so we can do better.  */
+  bool calls_read_all;
+  bool calls_write_all;
+};
+
+/* Statics that are read and written by some set of functions. The
+   local ones are based on the loads and stores local to the function.
+   The global ones are based on the local info as well as the
+   transitive closure of the functions that are called.  The
+   structures are separated to allow the global structures to be
+   shared between several functions since every function within a
+   strongly connected component will have the same information.  This
+   sharing saves both time and space in the computation of the vectors
+   as well as their translation from decl_uid form to ann_uid
+   form.  */ 
+
+struct ipa_reference_global_vars_info_d
+{
+  bitmap statics_read;
+  bitmap statics_written;
+  bitmap statics_not_read;
+  bitmap statics_not_written;
+};
+
+typedef struct ipa_reference_local_vars_info_d *ipa_reference_local_vars_info_t;
+typedef struct ipa_reference_global_vars_info_d *ipa_reference_global_vars_info_t;
+struct ipa_reference_vars_info_d 
+{
+  ipa_reference_local_vars_info_t local;
+  ipa_reference_global_vars_info_t global;
+};
+
+typedef struct ipa_reference_vars_info_d *ipa_reference_vars_info_t;
+
+/* This splay tree contains all of the static variables that are
+   being considered by the compilation level alias analysis.  For
+   module_at_a_time compilation, this is the set of static but not
+   public variables.  Any variables that either have their address
+   taken or participate in otherwise unsavory operations are deleted
+   from this list.  */
+static GTY((param1_is(int), param2_is(tree)))
+     splay_tree reference_vars_to_consider;
+
+/* This bitmap is used to knock out the module static variables whose
+   addresses have been taken and passed around.  */
+static bitmap module_statics_escape;
+
+/* This bitmap is used to knock out the module static variables that
+   are not readonly.  */
+static bitmap module_statics_written;
+
+/* A bit is set for every module static we are considering.  This is
+   ored into the local info when asm code is found that clobbers all
+   memory. */
+static bitmap all_module_statics;
+
+static struct pointer_set_t *visited_nodes;
+
+/* Obstack holding bitmaps of local analysis (live from analysis to
+   propagation)  */
+static bitmap_obstack local_info_obstack;
+/* Obstack holding global analysis live forever.  */
+static bitmap_obstack global_info_obstack;
+
+/* Holders of ipa cgraph hooks: */
+static struct cgraph_node_hook_list *function_insertion_hook_holder;
+static struct cgraph_2node_hook_list *node_duplication_hook_holder;
+static struct cgraph_node_hook_list *node_removal_hook_holder;
+
+enum initialization_status_t
+{
+  UNINITIALIZED,
+  RUNNING,
+  FINISHED
+};
+
+tree memory_identifier_string;
+
+/* Vector where the reference var infos are actually stored. */
+DEF_VEC_P (ipa_reference_vars_info_t);
+DEF_VEC_ALLOC_P (ipa_reference_vars_info_t, heap);
+static VEC (ipa_reference_vars_info_t, heap) *ipa_reference_vars_vector;
+
+/* Return the ipa_reference_vars structure starting from the cgraph NODE.  */
+static inline ipa_reference_vars_info_t
+get_reference_vars_info (struct cgraph_node *node)
+{
+  if (!ipa_reference_vars_vector
+      || VEC_length (ipa_reference_vars_info_t, ipa_reference_vars_vector) <= (unsigned int)node->uid)
+    return NULL;
+  return VEC_index (ipa_reference_vars_info_t, ipa_reference_vars_vector, node->uid);
+}
+
+/* Return the ipa_reference_vars structure starting from the cgraph NODE.  */
+static inline void
+set_reference_vars_info (struct cgraph_node *node, ipa_reference_vars_info_t info)
+{
+  if (!ipa_reference_vars_vector
+      || VEC_length (ipa_reference_vars_info_t, ipa_reference_vars_vector) <= (unsigned int)node->uid)
+     VEC_safe_grow_cleared (ipa_reference_vars_info_t, heap, ipa_reference_vars_vector, node->uid + 1);
+  VEC_replace (ipa_reference_vars_info_t, ipa_reference_vars_vector, node->uid, info);
+}
+
+/* Get a bitmap that contains all of the locally referenced static
+   variables for function FN.  */
+static ipa_reference_local_vars_info_t
+get_local_reference_vars_info (struct cgraph_node *fn) 
+{
+  ipa_reference_vars_info_t info = get_reference_vars_info (fn);
+
+  if (info)
+    return info->local;
+  else
+    /* This phase was not run.  */ 
+    return NULL;
+}
+
+/* Get a bitmap that contains all of the globally referenced static
+   variables for function FN.  */
+ 
+static ipa_reference_global_vars_info_t
+get_global_reference_vars_info (struct cgraph_node *fn) 
+{
+  ipa_reference_vars_info_t info = get_reference_vars_info (fn);
+
+  if (info)
+    return info->global;
+  else
+    /* This phase was not run.  */ 
+    return NULL;
+}
+
+/* Return a bitmap indexed by VAR_DECL uid for the static variables
+   that are read during the execution of the function FN.  Returns
+   NULL if no data is available.  */
+
+bitmap 
+ipa_reference_get_read_global (struct cgraph_node *fn) 
+{
+  ipa_reference_global_vars_info_t g = get_global_reference_vars_info (fn);
+  if (g) 
+    return g->statics_read;
+  else
+    return NULL;
+}
+
+/* Return a bitmap indexed by VAR_DECL uid for the static variables
+   that are written during the execution of the function FN.  Note
+   that variables written may or may not be read during the function
+   call.  Returns NULL if no data is available.  */
+
+bitmap 
+ipa_reference_get_written_global (struct cgraph_node *fn) 
+{
+  ipa_reference_global_vars_info_t g = get_global_reference_vars_info (fn);
+  if (g) 
+    return g->statics_written;
+  else
+    return NULL;
+}
+
+/* Return a bitmap indexed by_DECL_UID uid for the static variables
+   that are not read during the execution of the function FN.  Returns
+   NULL if no data is available.  */
+
+bitmap 
+ipa_reference_get_not_read_global (struct cgraph_node *fn) 
+{
+  ipa_reference_global_vars_info_t g = get_global_reference_vars_info (fn);
+  if (g) 
+    return g->statics_not_read;
+  else
+    return NULL;
+}
+
+/* Return a bitmap indexed by DECL_UID uid for the static variables
+   that are not written during the execution of the function FN.  Note
+   that variables written may or may not be read during the function
+   call.  Returns NULL if no data is available.  */
+
+bitmap 
+ipa_reference_get_not_written_global (struct cgraph_node *fn) 
+{
+  ipa_reference_global_vars_info_t g = get_global_reference_vars_info (fn);
+  if (g) 
+    return g->statics_not_written;
+  else
+    return NULL;
+}
+
+
+
+/* Add VAR to all_module_statics and the two
+   reference_vars_to_consider* sets.  */
+
+static inline void 
+add_static_var (tree var) 
+{
+  int uid = DECL_UID (var);
+  gcc_assert (TREE_CODE (var) == VAR_DECL);
+  if (!bitmap_bit_p (all_module_statics, uid))
+    {
+      splay_tree_insert (reference_vars_to_consider,
+			 uid, (splay_tree_value)var);
+      bitmap_set_bit (all_module_statics, uid);
+    }
+}
+
+/* Return true if the variable T is the right kind of static variable to
+   perform compilation unit scope escape analysis.  */
+
+static inline bool 
+has_proper_scope_for_analysis (tree t)
+{
+  /* If the variable has the "used" attribute, treat it as if it had a
+     been touched by the devil.  */
+  if (lookup_attribute ("used", DECL_ATTRIBUTES (t)))
+    return false;
+
+  /* Do not want to do anything with volatile except mark any
+     function that uses one to be not const or pure.  */
+  if (TREE_THIS_VOLATILE (t)) 
+    return false;
+
+  /* Do not care about a local automatic that is not static.  */
+  if (!TREE_STATIC (t) && !DECL_EXTERNAL (t))
+    return false;
+
+  if (DECL_EXTERNAL (t) || TREE_PUBLIC (t))
+    return false;
+
+  /* We cannot touch decls where the type needs constructing.  */
+  if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (t)))
+    return false;
+
+  /* This is a variable we care about.  Check if we have seen it
+     before, and if not add it the set of variables we care about.  */
+  if (!bitmap_bit_p (all_module_statics, DECL_UID (t)))
+    add_static_var (t);
+
+  return true;
+}
+
+/* Mark tree T as having address taken.  */
+
+static void
+mark_address_taken (tree x)
+{
+  if (TREE_CODE (x) == VAR_DECL
+      && module_statics_escape && has_proper_scope_for_analysis (x))
+    bitmap_set_bit (module_statics_escape, DECL_UID (x));
+}
+
+/* Mark load of T.  */
+
+static void
+mark_load (ipa_reference_local_vars_info_t local, 
+	   tree t)
+{
+  if (TREE_CODE (t) == VAR_DECL
+      && has_proper_scope_for_analysis (t))
+    bitmap_set_bit (local->statics_read, DECL_UID (t));
+}
+
+/* Mark store of T.  */
+
+static void
+mark_store (ipa_reference_local_vars_info_t local, 
+	   tree t)
+{
+  if (TREE_CODE (t) == VAR_DECL
+      && has_proper_scope_for_analysis (t))
+    {
+      if (local)
+	bitmap_set_bit (local->statics_written, DECL_UID (t));
+      /* Mark the write so we can tell which statics are
+	 readonly.  */
+      if (module_statics_written)
+	bitmap_set_bit (module_statics_written, DECL_UID (t));
+    }
+}
+
+/* Look for memory clobber and set read_all/write_all if present.  */
+
+static void
+check_asm_memory_clobber (ipa_reference_local_vars_info_t local, gimple stmt)
+{
+  size_t i;
+  tree op;
+  
+  for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
+    {
+      op = gimple_asm_clobber_op (stmt, i);
+      if (simple_cst_equal(TREE_VALUE (op), memory_identifier_string) == 1) 
+	{
+	  /* Abandon all hope, ye who enter here. */
+	  local->calls_read_all = true;
+	  local->calls_write_all = true;
+	}      
+    }
+}
+
+/* Look for external calls and set read_all/write_all correspondingly.  */
+
+static void
+check_call (ipa_reference_local_vars_info_t local, gimple stmt)
+{
+  int flags = gimple_call_flags (stmt);
+  tree callee_t = gimple_call_fndecl (stmt);
+  enum availability avail = AVAIL_NOT_AVAILABLE;
+
+  if (callee_t)
+    {
+      struct cgraph_node* callee = cgraph_node(callee_t);
+      avail = cgraph_function_body_availability (callee);
+    }
+
+  if (avail <= AVAIL_OVERWRITABLE)
+    if (local) 
+      {
+	if (flags & ECF_CONST) 
+	  ;
+	else if (flags & ECF_PURE)
+	  local->calls_read_all = true;
+	else 
+	  {
+	    local->calls_read_all = true;
+	    local->calls_write_all = true;
+	  }
+      }
+   /* TODO: To be able to produce sane results, we should also handle
+      common builtins, in particular throw.
+      Indirect calls hsould be only counted and as inliner is replacing them
+      by direct calls, we can conclude if any indirect calls are left in body */
+}
+
+/* TP is the part of the tree currently under the microscope.
+   WALK_SUBTREES is part of the walk_tree api but is unused here.
+   DATA is cgraph_node of the function being walked.  */
+
+static tree
+scan_stmt_for_static_refs (gimple_stmt_iterator *gsip,
+			   struct cgraph_node *fn)
+{
+  gimple stmt = gsi_stmt (*gsip);
+  ipa_reference_local_vars_info_t local = NULL;
+  unsigned int i;
+  bitmap_iterator bi;
+
+  if (fn)
+    local = get_reference_vars_info (fn)->local;
+
+  if (gimple_loaded_syms (stmt))
+    EXECUTE_IF_SET_IN_BITMAP (gimple_loaded_syms (stmt), 0, i, bi)
+      mark_load (local, referenced_var_lookup (i));
+  if (gimple_stored_syms (stmt))
+    EXECUTE_IF_SET_IN_BITMAP (gimple_stored_syms (stmt), 0, i, bi)
+      mark_store (local, referenced_var_lookup (i));
+  if (gimple_addresses_taken (stmt))
+    EXECUTE_IF_SET_IN_BITMAP (gimple_addresses_taken (stmt), 0, i, bi)
+      mark_address_taken (referenced_var_lookup (i));
+
+  switch (gimple_code (stmt))
+    {
+    case GIMPLE_CALL:
+      check_call (local, stmt);
+      break;
+      
+    case GIMPLE_ASM:
+      check_asm_memory_clobber (local, stmt);
+      break;
+
+    /* We used to check nonlocal labels here and set them as potentially modifying
+       everything.  This is not needed, since we can get to nonlocal label only
+       from callee and thus we will get info propagated.  */
+
+    default:
+      break;
+    }
+  
+  return NULL;
+}
+
+/* Call-back to scan variable initializers for static references.  
+   Called using walk_tree.  */
+
+static tree
+scan_initializer_for_static_refs (tree *tp, int *walk_subtrees,
+				  void *data ATTRIBUTE_UNUSED)
+{
+  tree t = *tp;
+
+  if (TREE_CODE (t) == ADDR_EXPR)
+    {
+      mark_address_taken (get_base_var (t));
+      *walk_subtrees = 0;
+    }
+  /* Save some cycles by not walking types and declaration as we
+     won't find anything useful there anyway.  */
+  else if (IS_TYPE_OR_DECL_P (*tp))
+    *walk_subtrees = 0;
+ 
+  return NULL;
+}
+
+/* Lookup the tree node for the static variable that has UID.  */
+static tree
+get_static_decl (int index)
+{
+  splay_tree_node stn = 
+    splay_tree_lookup (reference_vars_to_consider, index);
+  if (stn)
+    return (tree)stn->value;
+  return NULL;
+}
+
+/* Lookup the tree node for the static variable that has UID and
+   convert the name to a string for debugging.  */
+
+static const char *
+get_static_name (int index)
+{
+  splay_tree_node stn = 
+    splay_tree_lookup (reference_vars_to_consider, index);
+  if (stn)
+    return lang_hooks.decl_printable_name ((tree)(stn->value), 2);
+  return NULL;
+}
+
+/* Or in all of the bits from every callee of X into X_GLOBAL, the caller's cycle,
+   bit vector.  There are several cases to check to avoid the sparse
+   bitmap oring.  */
+
+static void
+propagate_bits (ipa_reference_global_vars_info_t x_global, struct cgraph_node *x)
+{
+  struct cgraph_edge *e;
+  for (e = x->callees; e; e = e->next_callee) 
+    {
+      struct cgraph_node *y = e->callee;
+
+      /* Only look at the master nodes and skip external nodes.  */
+      if (cgraph_function_body_availability (e->callee) > AVAIL_OVERWRITABLE)
+	{
+	  if (get_reference_vars_info (y))
+	    {
+	      ipa_reference_vars_info_t y_info 
+		= get_reference_vars_info (y);
+	      ipa_reference_global_vars_info_t y_global = y_info->global;
+
+	      /* Calls in current cycle do not have global computed yet.  */
+	      if (!y_info->global)
+		continue;
+	      
+	      if (x_global->statics_read
+		  != all_module_statics)
+		{
+		  if (y_global->statics_read 
+		      == all_module_statics)
+		    {
+		      BITMAP_FREE (x_global->statics_read);
+		      x_global->statics_read 
+			= all_module_statics;
+		    }
+		  /* Skip bitmaps that are pointer equal to node's bitmap
+		     (no reason to spin within the cycle).  */
+		  else if (x_global->statics_read 
+			   != y_global->statics_read)
+		    bitmap_ior_into (x_global->statics_read,
+				     y_global->statics_read);
+		}
+	      
+	      if (x_global->statics_written 
+		  != all_module_statics)
+		{
+		  if (y_global->statics_written 
+		      == all_module_statics)
+		    {
+		      BITMAP_FREE (x_global->statics_written);
+		      x_global->statics_written 
+			= all_module_statics;
+		    }
+		  /* Skip bitmaps that are pointer equal to node's bitmap
+		     (no reason to spin within the cycle).  */
+		  else if (x_global->statics_written 
+			   != y_global->statics_written)
+		    bitmap_ior_into (x_global->statics_written,
+				     y_global->statics_written);
+		}
+	    }
+	  else 
+	    gcc_unreachable ();
+	}
+    }
+}
+
+/* The init routine for analyzing global static variable usage.  See
+   comments at top for description.  */
+static void 
+ipa_init (void) 
+{
+  memory_identifier_string = build_string(7, "memory");
+
+  reference_vars_to_consider =
+    splay_tree_new_ggc (splay_tree_compare_ints);
+
+  bitmap_obstack_initialize (&local_info_obstack);
+  bitmap_obstack_initialize (&global_info_obstack);
+  module_statics_escape = BITMAP_ALLOC (&local_info_obstack);
+  module_statics_written = BITMAP_ALLOC (&local_info_obstack);
+  all_module_statics = BITMAP_ALLOC (&global_info_obstack);
+
+  /* There are some shared nodes, in particular the initializers on
+     static declarations.  We do not need to scan them more than once
+     since all we would be interested in are the addressof
+     operations.  */
+  visited_nodes = pointer_set_create ();
+}
+
+/* Check out the rhs of a static or global initialization VNODE to see
+   if any of them contain addressof operations.  Note that some of
+   these variables may  not even be referenced in the code in this
+   compilation unit but their right hand sides may contain references
+   to variables defined within this unit.  */
+
+static void 
+analyze_variable (struct varpool_node *vnode)
+{
+  struct walk_stmt_info wi;
+  tree global = vnode->decl;
+
+  memset (&wi, 0, sizeof (wi));
+  wi.pset = visited_nodes;
+  walk_tree (&DECL_INITIAL (global), scan_initializer_for_static_refs,
+             &wi, wi.pset);
+}
+
+/* Set up the persistent info for FN.  */
+
+static ipa_reference_local_vars_info_t
+init_function_info (struct cgraph_node *fn)
+{
+  ipa_reference_vars_info_t info 
+    = XCNEW (struct ipa_reference_vars_info_d);
+  ipa_reference_local_vars_info_t l
+    = XCNEW (struct ipa_reference_local_vars_info_d);
+
+  /* Add the info to the tree's annotation.  */
+  set_reference_vars_info (fn, info);
+
+  info->local = l;
+  l->statics_read = BITMAP_ALLOC (&local_info_obstack);
+  l->statics_written = BITMAP_ALLOC (&local_info_obstack);
+
+  return l;
+}
+
+/* This is the main routine for finding the reference patterns for
+   global variables within a function FN.  */
+  
+static void
+analyze_function (struct cgraph_node *fn)
+{
+  tree decl = fn->decl;
+  struct function *this_cfun = DECL_STRUCT_FUNCTION (decl);
+  basic_block this_block;
+#ifdef ENABLE_CHECKING
+  tree step;
+#endif
+
+  if (dump_file)
+    fprintf (dump_file, "\n local analysis of %s\n", cgraph_node_name (fn));
+
+  push_cfun (DECL_STRUCT_FUNCTION (decl));
+  current_function_decl = decl;
+  
+  init_function_info (fn);
+  FOR_EACH_BB_FN (this_block, this_cfun)
+    {
+      gimple_stmt_iterator gsi;
+      gimple phi;
+      tree op;
+      use_operand_p use;
+      ssa_op_iter iter;
+
+      /* Find the addresses taken in phi node arguments.  */
+      for (gsi = gsi_start_phis (this_block);
+	   !gsi_end_p (gsi);
+	   gsi_next (&gsi))
+	{
+	  phi = gsi_stmt (gsi);
+	  FOR_EACH_PHI_ARG (use, phi, iter, SSA_OP_USE)
+	    {
+	      op = USE_FROM_PTR (use);
+	      if (TREE_CODE (op) == ADDR_EXPR)
+		mark_address_taken (get_base_var (op));
+	    }
+	}
+
+      for (gsi = gsi_start_bb (this_block); !gsi_end_p (gsi); gsi_next (&gsi))
+	scan_stmt_for_static_refs (&gsi, fn);
+    }
+
+#ifdef ENABLE_CHECKING
+  /* Verify that all local initializers was expanded by gimplifier.  */
+  for (step = DECL_STRUCT_FUNCTION (decl)->local_decls;
+       step;
+       step = TREE_CHAIN (step))
+    {
+      tree var = TREE_VALUE (step);
+      if (TREE_CODE (var) == VAR_DECL 
+	  && DECL_INITIAL (var)
+	  && !TREE_STATIC (var))
+	gcc_unreachable ();
+    }
+#endif
+  pop_cfun ();
+  current_function_decl = NULL;
+}
+
+/* Remove local data associated with function FN.  */
+static void
+clean_function_local_data (struct cgraph_node *fn)
+{
+  ipa_reference_vars_info_t info = get_reference_vars_info (fn);
+  ipa_reference_local_vars_info_t l = info->local;
+  if (l)
+    {
+      if (l->statics_read
+	  && l->statics_read != all_module_statics)
+	BITMAP_FREE (l->statics_read);
+      if (l->statics_written
+	  &&l->statics_written != all_module_statics)
+	BITMAP_FREE (l->statics_written);
+      free (l);
+      info->local = NULL;
+    }
+}
+
+/* Remove all data associated with function FN.  */
+
+static void
+clean_function (struct cgraph_node *fn)
+{
+  ipa_reference_vars_info_t info = get_reference_vars_info (fn);
+  ipa_reference_global_vars_info_t g = info->global;
+  
+  clean_function_local_data (fn);
+  if (g)
+    {
+      if (g->statics_read
+	  && g->statics_read != all_module_statics)
+	BITMAP_FREE (g->statics_read);
+      
+      if (g->statics_written
+	  && g->statics_written != all_module_statics)
+	BITMAP_FREE (g->statics_written);
+      
+      if (g->statics_not_read
+	  && g->statics_not_read != all_module_statics)
+	BITMAP_FREE (g->statics_not_read);
+      
+      if (g->statics_not_written
+	  && g->statics_not_written != all_module_statics)
+	BITMAP_FREE (g->statics_not_written);
+      free (g);
+      info->global = NULL;
+    }
+  
+  free (get_reference_vars_info (fn));
+  set_reference_vars_info (fn, NULL);
+}
+
+/* Called when new function is inserted to callgraph late.  */
+static void
+add_new_function (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED)
+{
+  /* There are some shared nodes, in particular the initializers on
+     static declarations.  We do not need to scan them more than once
+     since all we would be interested in are the addressof
+     operations.  */
+  analyze_function (node);
+  visited_nodes = NULL;
+}
+
+static bitmap
+copy_local_bitmap (bitmap src)
+{
+  bitmap dst;
+  if (!src)
+    return NULL;
+  if (src == all_module_statics)
+    return all_module_statics;
+  dst = BITMAP_ALLOC (&local_info_obstack);
+  bitmap_copy (dst, src);
+  return dst;
+}
+
+static bitmap
+copy_global_bitmap (bitmap src)
+{
+  bitmap dst;
+  if (!src)
+    return NULL;
+  if (src == all_module_statics)
+    return all_module_statics;
+  dst = BITMAP_ALLOC (&global_info_obstack);
+  bitmap_copy (dst, src);
+  return dst;
+}
+
+/* Called when new clone is inserted to callgraph late.  */
+
+static void
+duplicate_node_data (struct cgraph_node *src, struct cgraph_node *dst,
+	 	     void *data ATTRIBUTE_UNUSED)
+{
+  ipa_reference_global_vars_info_t ginfo;
+  ipa_reference_local_vars_info_t linfo;
+  ipa_reference_global_vars_info_t dst_ginfo;
+  ipa_reference_local_vars_info_t dst_linfo;
+
+  ginfo = get_global_reference_vars_info (src);
+  linfo = get_local_reference_vars_info (src);
+  if (!linfo && !ginfo)
+    return;
+  init_function_info (dst);
+  if (linfo)
+    {
+      dst_linfo = get_local_reference_vars_info (dst);
+      dst_linfo->statics_read = copy_local_bitmap (linfo->statics_read);
+      dst_linfo->statics_written = copy_local_bitmap (linfo->statics_written);
+      dst_linfo->calls_read_all = linfo->calls_read_all;
+      dst_linfo->calls_write_all = linfo->calls_write_all;
+    }
+  if (ginfo)
+    {
+      get_reference_vars_info (dst)->global = XCNEW (struct ipa_reference_global_vars_info_d);
+      dst_ginfo = get_global_reference_vars_info (dst);
+      dst_ginfo->statics_read = copy_global_bitmap (ginfo->statics_read);
+      dst_ginfo->statics_written = copy_global_bitmap (ginfo->statics_written);
+      dst_ginfo->statics_not_read = copy_global_bitmap (ginfo->statics_not_read);
+      dst_ginfo->statics_not_written = copy_global_bitmap (ginfo->statics_not_written);
+    }
+}
+
+/* Called when node is removed.  */
+
+static void
+remove_node_data (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED)
+{
+  if (get_reference_vars_info (node))
+    clean_function (node);
+}
+
+/* Analyze each function in the cgraph to see which global or statics
+   are read or written.  */
+
+static void 
+generate_summary (void)
+{
+  struct cgraph_node *node;
+  struct varpool_node *vnode;
+  unsigned int index;
+  bitmap_iterator bi;
+  bitmap module_statics_readonly;
+  bitmap bm_temp;
+  
+  function_insertion_hook_holder =
+      cgraph_add_function_insertion_hook (&add_new_function, NULL);
+  node_removal_hook_holder =
+      cgraph_add_node_removal_hook (&remove_node_data, NULL);
+  node_duplication_hook_holder =
+      cgraph_add_node_duplication_hook (&duplicate_node_data, NULL);
+  ipa_init ();
+  module_statics_readonly = BITMAP_ALLOC (&local_info_obstack);
+  bm_temp = BITMAP_ALLOC (&local_info_obstack);
+
+  /* Process all of the variables first.  */
+  FOR_EACH_STATIC_INITIALIZER (vnode)
+    analyze_variable (vnode);
+
+  /* Process all of the functions next. 
+
+     We do not want to process any of the clones so we check that this
+     is a master clone.  However, we do need to process any
+     AVAIL_OVERWRITABLE functions (these are never clones) because
+     they may cause a static variable to escape.  The code that can
+     overwrite such a function cannot access the statics because it
+     would not be in the same compilation unit.  When the analysis is
+     finished, the computed information of these AVAIL_OVERWRITABLE is
+     replaced with worst case info.  
+  */
+  for (node = cgraph_nodes; node; node = node->next)
+    if (cgraph_function_body_availability (node) >= AVAIL_OVERWRITABLE)
+      analyze_function (node);
+
+  pointer_set_destroy (visited_nodes);
+  visited_nodes = NULL;
+
+  /* Prune out the variables that were found to behave badly
+     (i.e. have their address taken).  */
+  EXECUTE_IF_SET_IN_BITMAP (module_statics_escape, 0, index, bi)
+    {
+      splay_tree_remove (reference_vars_to_consider, index);
+    }
+  
+  bitmap_and_compl_into (all_module_statics, 
+			 module_statics_escape);
+  
+  bitmap_and_compl (module_statics_readonly, all_module_statics,
+		    module_statics_written);
+  
+  /* If the address is not taken, we can unset the addressable bit
+     on this variable.  */
+  EXECUTE_IF_SET_IN_BITMAP (all_module_statics, 0, index, bi)
+    {
+      tree var = get_static_decl (index);
+      TREE_ADDRESSABLE (var) = 0;
+      if (dump_file) 
+	fprintf (dump_file, "Not TREE_ADDRESSABLE var %s\n",
+		 get_static_name (index));
+    }
+  
+  /* If the variable is never written, we can set the TREE_READONLY
+     flag.  Additionally if it has a DECL_INITIAL that is made up of
+     constants we can treat the entire global as a constant.  */
+  
+  bitmap_and_compl (module_statics_readonly, all_module_statics,
+		    module_statics_written);
+  EXECUTE_IF_SET_IN_BITMAP (module_statics_readonly, 0, index, bi)
+    {
+      tree var = get_static_decl (index);
+      
+      /* Ignore variables in named sections - changing TREE_READONLY
+	 changes the section flags, potentially causing conflicts with
+	 other variables in the same named section.  */
+      if (DECL_SECTION_NAME (var) == NULL_TREE)
+	{
+	  TREE_READONLY (var) = 1;
+	  if (dump_file)
+	    fprintf (dump_file, "read-only var %s\n", 
+		     get_static_name (index));
+	}
+    }
+  
+  BITMAP_FREE(module_statics_escape);
+  BITMAP_FREE(module_statics_written);
+  module_statics_escape = NULL;
+  module_statics_written = NULL;
+  
+  if (dump_file)
+    EXECUTE_IF_SET_IN_BITMAP (all_module_statics, 0, index, bi)
+      {
+	fprintf (dump_file, "\nPromotable global:%s",
+		 get_static_name (index));
+      }
+  
+  for (node = cgraph_nodes; node; node = node->next)
+    if (cgraph_function_body_availability (node) >= AVAIL_OVERWRITABLE)
+      {
+	ipa_reference_local_vars_info_t l;
+	l = get_reference_vars_info (node)->local;
+	
+	/* Any variables that are not in all_module_statics are
+	   removed from the local maps.  This will include all of the
+	   variables that were found to escape in the function
+	   scanning.  */
+	bitmap_and_into (l->statics_read, 
+			 all_module_statics);
+	bitmap_and_into (l->statics_written, 
+			 all_module_statics);
+      }
+  
+  BITMAP_FREE(module_statics_readonly);
+  BITMAP_FREE(bm_temp);
+  
+  if (dump_file)
+    for (node = cgraph_nodes; node; node = node->next)
+      if (cgraph_function_body_availability (node) >= AVAIL_OVERWRITABLE)
+	{
+	  ipa_reference_local_vars_info_t l;
+	  unsigned int index;
+	  bitmap_iterator bi;
+	  
+	  l = get_reference_vars_info (node)->local;
+	  fprintf (dump_file, 
+		   "\nFunction name:%s/%i:", 
+		   cgraph_node_name (node), node->uid);
+	  fprintf (dump_file, "\n  locals read: ");
+	  EXECUTE_IF_SET_IN_BITMAP (l->statics_read,
+				    0, index, bi)
+	    {
+	      fprintf (dump_file, "%s ",
+		       get_static_name (index));
+	    }
+	  fprintf (dump_file, "\n  locals written: ");
+	  EXECUTE_IF_SET_IN_BITMAP (l->statics_written,
+				    0, index, bi)
+	    {
+	      fprintf(dump_file, "%s ",
+		      get_static_name (index));
+	    }
+	  if (l->calls_read_all)
+	     fprintf (dump_file, "\n  calls read all: ");
+	  if (l->calls_write_all)
+	     fprintf (dump_file, "\n  calls read all: ");
+	}
+}
+
+/* Produce the global information by preforming a transitive closure
+   on the local information that was produced by ipa_analyze_function
+   and ipa_analyze_variable.  */
+
+static unsigned int
+propagate (void)
+{
+  struct cgraph_node *node;
+  struct cgraph_node *w;
+  struct cgraph_node **order =
+    XCNEWVEC (struct cgraph_node *, cgraph_n_nodes);
+  int order_pos = ipa_utils_reduced_inorder (order, false, true);
+  int i;
+
+  cgraph_remove_function_insertion_hook (function_insertion_hook_holder);
+  if (dump_file) 
+    dump_cgraph (dump_file);
+
+  /* Propagate the local information thru the call graph to produce
+     the global information.  All the nodes within a cycle will have
+     the same info so we collapse cycles first.  Then we can do the
+     propagation in one pass from the leaves to the roots.  */
+  order_pos = ipa_utils_reduced_inorder (order, true, true);
+  if (dump_file)
+    ipa_utils_print_order(dump_file, "reduced", order, order_pos);
+
+  for (i = 0; i < order_pos; i++ )
+    {
+      ipa_reference_vars_info_t node_info;
+      ipa_reference_global_vars_info_t node_g = 
+	XCNEW (struct ipa_reference_global_vars_info_d);
+      ipa_reference_local_vars_info_t node_l;
+      
+      bool read_all;
+      bool write_all;
+      struct ipa_dfs_info * w_info;
+
+      node = order[i];
+      node_info = get_reference_vars_info (node);
+      if (!node_info) 
+	{
+	  dump_cgraph_node (stderr, node);
+	  dump_cgraph (stderr);
+	  gcc_unreachable ();
+	}
+
+      gcc_assert (!node_info->global);
+      node_l = node_info->local;
+
+      read_all = node_l->calls_read_all;
+      write_all = node_l->calls_write_all;
+
+      /* If any node in a cycle is calls_read_all or calls_write_all
+	 they all are. */
+      w_info = (struct ipa_dfs_info *) node->aux;
+      w = w_info->next_cycle;
+      while (w)
+	{
+	  ipa_reference_local_vars_info_t w_l = 
+	    get_reference_vars_info (w)->local;
+	  read_all |= w_l->calls_read_all;
+	  write_all |= w_l->calls_write_all;
+
+	  w_info = (struct ipa_dfs_info *) w->aux;
+	  w = w_info->next_cycle;
+	}
+
+      /* Initialized the bitmaps for the reduced nodes */
+      if (read_all) 
+	node_g->statics_read = all_module_statics;
+      else 
+	{
+	  node_g->statics_read = BITMAP_ALLOC (&global_info_obstack);
+	  bitmap_copy (node_g->statics_read, 
+		       node_l->statics_read);
+	}
+
+      if (write_all) 
+	node_g->statics_written = all_module_statics;
+      else
+	{
+	  node_g->statics_written = BITMAP_ALLOC (&global_info_obstack);
+	  bitmap_copy (node_g->statics_written, 
+		       node_l->statics_written);
+	}
+
+      propagate_bits (node_g, node);
+      w_info = (struct ipa_dfs_info *) node->aux;
+      w = w_info->next_cycle;
+      while (w)
+	{
+	  ipa_reference_vars_info_t w_ri = 
+	    get_reference_vars_info (w);
+	  ipa_reference_local_vars_info_t w_l = w_ri->local;
+	  
+	  /* These global bitmaps are initialized from the local info
+	     of all of the nodes in the region.  However there is no
+	     need to do any work if the bitmaps were set to
+	     all_module_statics.  */
+	  if (!read_all)
+	    bitmap_ior_into (node_g->statics_read,
+			     w_l->statics_read);
+	  if (!write_all)
+	    bitmap_ior_into (node_g->statics_written,
+			     w_l->statics_written);
+	  propagate_bits (node_g, w);
+	  w_info = (struct ipa_dfs_info *) w->aux;
+	  w = w_info->next_cycle;
+	}
+
+      /* All nodes within a cycle have the same global info bitmaps.  */
+      node_info->global = node_g;
+      w_info = (struct ipa_dfs_info *) node->aux;
+      w = w_info->next_cycle;
+      while (w)
+	{
+	  ipa_reference_vars_info_t w_ri = 
+	    get_reference_vars_info (w);
+
+	  gcc_assert (!w_ri->global);
+          w_ri->global = XCNEW (struct ipa_reference_global_vars_info_d);
+	  w_ri->global->statics_read = copy_global_bitmap (node_g->statics_read);
+	  w_ri->global->statics_written = copy_global_bitmap (node_g->statics_written);
+
+	  w_info = (struct ipa_dfs_info *) w->aux;
+	  w = w_info->next_cycle;
+	}
+    }
+
+  if (dump_file)
+    {
+      for (i = 0; i < order_pos; i++ )
+	{
+	  ipa_reference_vars_info_t node_info;
+	  ipa_reference_global_vars_info_t node_g;
+	  ipa_reference_local_vars_info_t node_l;
+	  unsigned int index;
+	  bitmap_iterator bi;
+	  struct ipa_dfs_info * w_info;
+
+	  node = order[i];
+	  node_info = get_reference_vars_info (node);
+	  node_g = node_info->global;
+	  node_l = node_info->local;
+	  fprintf (dump_file, 
+		   "\nFunction name:%s/%i:", 
+		   cgraph_node_name (node), node->uid);
+	  fprintf (dump_file, "\n  locals read: ");
+	  EXECUTE_IF_SET_IN_BITMAP (node_l->statics_read,
+				    0, index, bi)
+	    {
+	      fprintf (dump_file, "%s ",
+		       get_static_name (index));
+	    }
+	  fprintf (dump_file, "\n  locals written: ");
+	  EXECUTE_IF_SET_IN_BITMAP (node_l->statics_written,
+				    0, index, bi)
+	    {
+	      fprintf(dump_file, "%s ",
+		      get_static_name (index));
+	    }
+
+	  w_info = (struct ipa_dfs_info *) node->aux;
+	  w = w_info->next_cycle;
+	  while (w) 
+	    {
+	      ipa_reference_vars_info_t w_ri = 
+		get_reference_vars_info (w);
+	      ipa_reference_local_vars_info_t w_l = w_ri->local;
+	      fprintf (dump_file, "\n  next cycle: %s/%i ",
+		       cgraph_node_name (w), w->uid);
+ 	      fprintf (dump_file, "\n    locals read: ");
+	      EXECUTE_IF_SET_IN_BITMAP (w_l->statics_read,
+					0, index, bi)
+		{
+		  fprintf (dump_file, "%s ",
+			   get_static_name (index));
+		}
+
+	      fprintf (dump_file, "\n    locals written: ");
+	      EXECUTE_IF_SET_IN_BITMAP (w_l->statics_written,
+					0, index, bi)
+		{
+		  fprintf(dump_file, "%s ",
+			  get_static_name (index));
+		}
+	      
+
+	      w_info = (struct ipa_dfs_info *) w->aux;
+	      w = w_info->next_cycle;
+	    }
+	  fprintf (dump_file, "\n  globals read: ");
+	  EXECUTE_IF_SET_IN_BITMAP (node_g->statics_read,
+				    0, index, bi)
+	    {
+	      fprintf (dump_file, "%s ",
+		       get_static_name (index));
+	    }
+	  fprintf (dump_file, "\n  globals written: ");
+	  EXECUTE_IF_SET_IN_BITMAP (node_g->statics_written,
+				    0, index, bi)
+	    {
+	      fprintf (dump_file, "%s ",
+		       get_static_name (index));
+	    }
+	}
+    }
+
+  /* Cleanup. */
+  for (i = 0; i < order_pos; i++ )
+    {
+      ipa_reference_vars_info_t node_info;
+      ipa_reference_global_vars_info_t node_g;
+      node = order[i];
+      node_info = get_reference_vars_info (node);
+      node_g = node_info->global;
+      
+      /* Create the complimentary sets.  These are more useful for
+	 certain apis.  */
+      node_g->statics_not_read = BITMAP_ALLOC (&global_info_obstack);
+      node_g->statics_not_written = BITMAP_ALLOC (&global_info_obstack);
+
+      if (node_g->statics_read != all_module_statics) 
+	bitmap_and_compl (node_g->statics_not_read, 
+			  all_module_statics,
+			  node_g->statics_read);
+
+      if (node_g->statics_written 
+	  != all_module_statics) 
+	bitmap_and_compl (node_g->statics_not_written, 
+			  all_module_statics,
+			  node_g->statics_written);
+   }
+
+  free (order);
+
+  for (node = cgraph_nodes; node; node = node->next)
+    {
+      ipa_reference_vars_info_t node_info;
+      node_info = get_reference_vars_info (node);
+      /* Get rid of the aux information.  */
+      
+      if (node->aux)
+	{
+	  free (node->aux);
+	  node->aux = NULL;
+	}
+      
+      if (cgraph_function_body_availability (node) == AVAIL_OVERWRITABLE)
+	clean_function (node);
+      else if (node_info)
+	clean_function_local_data (node);
+    }
+  bitmap_obstack_release (&local_info_obstack);
+  return 0;
+}
+
+
+static bool
+gate_reference (void)
+{
+  return (flag_ipa_reference
+	  /* Don't bother doing anything if the program has errors.  */
+	  && !(errorcount || sorrycount));
+}
+
+struct ipa_opt_pass pass_ipa_reference =
+{
+ {
+  IPA_PASS,
+  "static-var",				/* name */
+  gate_reference,			/* gate */
+  propagate,			        /* execute */
+  NULL,					/* sub */
+  NULL,					/* next */
+  0,					/* static_pass_number */
+  TV_IPA_REFERENCE,		        /* tv_id */
+  0,	                                /* properties_required */
+  0,					/* properties_provided */
+  0,					/* properties_destroyed */
+  0,					/* todo_flags_start */
+  0                                     /* todo_flags_finish */
+ },
+ generate_summary,		        /* generate_summary */
+ NULL,					/* write_summary */
+ NULL,					/* read_summary */
+ NULL,					/* function_read_summary */
+ 0,					/* TODOs */
+ NULL,			                /* function_transform */
+ NULL					/* variable_transform */
+};
+
+#include "gt-ipa-reference.h"