Merge lto branch into trunk.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@152434 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 2067 insertions, 0 deletions

diff --git a/gcc/lto/lto.c b/gcc/lto/lto.c
new file mode 100644
index 00000000000..056d249a161
--- /dev/null
+++ b/gcc/lto/lto.c
@@ -0,0 +1,2067 @@
+/* Top-level LTO routines.
+   Copyright 2009 Free Software Foundation, Inc.
+   Contributed by CodeSourcery, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "opts.h"
+#include "toplev.h"
+#include "tree.h"
+#include "diagnostic.h"
+#include "tm.h"
+#include "libiberty.h"
+#include "cgraph.h"
+#include "ggc.h"
+#include "tree-ssa-operands.h"
+#include "tree-pass.h"
+#include "langhooks.h"
+#include "vec.h"
+#include "bitmap.h"
+#include "pointer-set.h"
+#include "ipa-prop.h"
+#include "common.h"
+#include "timevar.h"
+#include "gimple.h"
+#include "lto.h"
+#include "lto-tree.h"
+#include "lto-streamer.h"
+
+/* This needs to be included after config.h.  Otherwise, _GNU_SOURCE will not
+   be defined in time to set __USE_GNU in the system headers, and strsignal
+   will not be declared.  */
+#include <sys/mman.h>
+
+DEF_VEC_P(bitmap);
+DEF_VEC_ALLOC_P(bitmap,heap);
+
+/* Read the constructors and inits.  */
+
+static void
+lto_materialize_constructors_and_inits (struct lto_file_decl_data * file_data)
+{
+  size_t len;
+  const char *data = lto_get_section_data (file_data, 
+					   LTO_section_static_initializer,
+					   NULL, &len);
+  lto_input_constructors_and_inits (file_data, data);
+  lto_free_section_data (file_data, LTO_section_static_initializer, NULL,
+			 data, len);
+}
+
+/* Read the function body for the function associated with NODE if possible.  */
+
+static void
+lto_materialize_function (struct cgraph_node *node)
+{
+  tree decl;
+  struct lto_file_decl_data *file_data;
+  const char *data, *name;
+  size_t len;
+  tree step;
+
+  /* Ignore clone nodes.  Read the body only from the original one.
+     We may find clone nodes during LTRANS after WPA has made inlining
+     decisions.  */
+  if (node->clone_of)
+    return;
+
+  decl = node->decl;
+  file_data = node->local.lto_file_data;
+  name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)); 
+
+  /* We may have renamed the declaration, e.g., a static function.  */
+  name = lto_get_decl_name_mapping (file_data, name);
+
+  data = lto_get_section_data (file_data, LTO_section_function_body,
+			       name, &len);
+  if (data)
+    {
+      struct function *fn;
+
+      gcc_assert (!DECL_IS_BUILTIN (decl));
+
+      /* This function has a definition.  */
+      TREE_STATIC (decl) = 1;
+
+      gcc_assert (DECL_STRUCT_FUNCTION (decl) == NULL);
+      allocate_struct_function (decl, false);
+
+      /* Load the function body only if not operating in WPA mode.  In
+	 WPA mode, the body of the function is not needed.  */
+      if (!flag_wpa)
+	{
+	  lto_input_function_body (file_data, decl, data);
+	  lto_stats.num_function_bodies++;
+	}
+
+      fn = DECL_STRUCT_FUNCTION (decl);
+      lto_free_section_data (file_data, LTO_section_function_body, name,
+			     data, len);
+
+      /* Look for initializers of constant variables and private
+	 statics.  */
+      for (step = fn->local_decls; step; step = TREE_CHAIN (step))
+	{
+	  tree decl = TREE_VALUE (step);
+	  if (TREE_CODE (decl) == VAR_DECL
+	      && (TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
+	      && flag_unit_at_a_time)
+	    varpool_finalize_decl (decl);
+	}
+    }
+  else
+    DECL_EXTERNAL (decl) = 1;
+
+  /* Let the middle end know about the function.  */
+  rest_of_decl_compilation (decl, 1, 0);
+  if (cgraph_node (decl)->needed)
+    cgraph_mark_reachable_node (cgraph_node (decl));
+}
+
+
+/* Decode the content of memory pointed to by DATA in the the
+   in decl state object STATE. DATA_IN points to a data_in structure for
+   decoding. Return the address after the decoded object in the input.  */
+
+static const uint32_t *
+lto_read_in_decl_state (struct data_in *data_in, const uint32_t *data,
+			struct lto_in_decl_state *state)
+{
+  uint32_t ix;
+  tree decl;
+  uint32_t i, j;
+  
+  ix = *data++;
+  decl = lto_streamer_cache_get (data_in->reader_cache, (int) ix);
+  if (TREE_CODE (decl) != FUNCTION_DECL)
+    {
+      gcc_assert (decl == void_type_node);
+      decl = NULL_TREE;
+    }
+  state->fn_decl = decl;
+
+  for (i = 0; i < LTO_N_DECL_STREAMS; i++)
+    {
+      uint32_t size = *data++;
+      tree *decls = (tree *) xcalloc (size, sizeof (tree));
+
+      for (j = 0; j < size; j++)
+	{
+	  decls[j] = lto_streamer_cache_get (data_in->reader_cache, data[j]);
+
+	  /* Register every type in the global type table.  If the
+	     type existed already, use the existing type.  */
+	  if (TYPE_P (decls[j]))
+	    decls[j] = gimple_register_type (decls[j]);
+	}
+
+      state->streams[i].size = size;
+      state->streams[i].trees = decls;
+      data += size;
+    }
+
+  return data;
+}
+
+
+/* Read all the symbols from buffer DATA, using descriptors in DECL_DATA.
+   RESOLUTIONS is the set of symbols picked by the linker (read from the
+   resolution file when the linker plugin is being used).  */
+
+static void
+lto_read_decls (struct lto_file_decl_data *decl_data, const void *data,
+		VEC(ld_plugin_symbol_resolution_t,heap) *resolutions)
+{
+  const struct lto_decl_header *header = (const struct lto_decl_header *) data;
+  const int32_t decl_offset = sizeof (struct lto_decl_header);
+  const int32_t main_offset = decl_offset + header->decl_state_size;
+  const int32_t string_offset = main_offset + header->main_size;
+  struct lto_input_block ib_main;
+  struct data_in *data_in;
+  unsigned int i;
+  const uint32_t *data_ptr, *data_end;
+  uint32_t num_decl_states;
+
+  LTO_INIT_INPUT_BLOCK (ib_main, (const char *) data + main_offset, 0,
+			header->main_size);
+
+  data_in = lto_data_in_create (decl_data, (const char *) data + string_offset,
+				header->string_size, resolutions);
+
+  /* Read the global declarations and types.  */
+  while (ib_main.p < ib_main.len)
+    {
+      tree t = lto_input_tree (&ib_main, data_in);
+      gcc_assert (t && ib_main.p <= ib_main.len);
+    }
+
+  /* Read in lto_in_decl_state objects.  */
+  data_ptr = (const uint32_t *) ((const char*) data + decl_offset); 
+  data_end =
+     (const uint32_t *) ((const char*) data_ptr + header->decl_state_size);
+  num_decl_states = *data_ptr++;
+  
+  gcc_assert (num_decl_states > 0);
+  decl_data->global_decl_state = lto_new_in_decl_state ();
+  data_ptr = lto_read_in_decl_state (data_in, data_ptr,
+				     decl_data->global_decl_state);
+
+  /* Read in per-function decl states and enter them in hash table.  */
+  decl_data->function_decl_states =
+    htab_create (37, lto_hash_in_decl_state, lto_eq_in_decl_state, free);
+
+  for (i = 1; i < num_decl_states; i++)
+    {
+      struct lto_in_decl_state *state = lto_new_in_decl_state ();
+      void **slot;
+
+      data_ptr = lto_read_in_decl_state (data_in, data_ptr, state);
+      slot = htab_find_slot (decl_data->function_decl_states, state, INSERT);
+      gcc_assert (*slot == NULL);
+      *slot = state;
+    }
+
+  if (data_ptr != data_end)
+    internal_error ("bytecode stream: garbage at the end of symbols section");
+  
+  /* Set the current decl state to be the global state. */
+  decl_data->current_decl_state = decl_data->global_decl_state;
+
+  /* After each CU is read register and possibly merge global
+     symbols and their types.  */
+  lto_register_deferred_decls_in_symtab (data_in);
+
+  lto_data_in_delete (data_in);
+}
+
+/* Read resolution for file named FILE_NAME. The resolution is read from
+   RESOLUTION. An array with the symbol resolution is returned. The array
+   size is written to SIZE. */
+
+static VEC(ld_plugin_symbol_resolution_t,heap) *
+lto_resolution_read (FILE *resolution, const char *file_name)
+{
+  /* We require that objects in the resolution file are in the same
+     order as the lto1 command line. */
+  unsigned int name_len;
+  char *obj_name;
+  unsigned int num_symbols;
+  unsigned int i;
+  VEC(ld_plugin_symbol_resolution_t,heap) *ret = NULL;
+  unsigned max_index = 0;
+
+  if (!resolution)
+    return NULL;
+
+  name_len = strlen (file_name);
+  obj_name = XNEWVEC (char, name_len + 1);
+  fscanf (resolution, " ");   /* Read white space. */
+
+  fread (obj_name, sizeof (char), name_len, resolution);
+  obj_name[name_len] = '\0';
+  if (strcmp (obj_name, file_name) != 0)
+    internal_error ("unexpected file name %s in linker resolution file. "
+		    "Expected %s", obj_name, file_name);
+
+  free (obj_name);
+
+  fscanf (resolution, "%u", &num_symbols);
+
+  for (i = 0; i < num_symbols; i++)
+    {
+      unsigned index;
+      char r_str[27];
+      enum ld_plugin_symbol_resolution r;
+      unsigned int j;
+      unsigned int lto_resolution_str_len =
+	sizeof (lto_resolution_str) / sizeof (char *);
+
+      fscanf (resolution, "%u %26s", &index, r_str);
+      if (index > max_index)
+	max_index = index;
+
+      for (j = 0; j < lto_resolution_str_len; j++)
+	{
+	  if (strcmp (lto_resolution_str[j], r_str) == 0)
+	    {
+	      r = (enum ld_plugin_symbol_resolution) j;
+	      break;
+	    }
+	}
+      if (j >= lto_resolution_str_len)
+	internal_error ("tried to read past the end of the linker resolution "
+			"file");
+
+      VEC_safe_grow_cleared (ld_plugin_symbol_resolution_t, heap, ret,
+			     index + 1);
+      VEC_replace (ld_plugin_symbol_resolution_t, ret, index, r);
+    }
+
+  return ret;
+}
+
+/* Generate a TREE representation for all types and external decls
+   entities in FILE.  
+
+   Read all of the globals out of the file.  Then read the cgraph
+   and process the .o index into the cgraph nodes so that it can open
+   the .o file to load the functions and ipa information.   */
+
+static struct lto_file_decl_data *
+lto_file_read (lto_file *file, FILE *resolution_file)
+{
+  struct lto_file_decl_data *file_data;
+  const char *data;
+  size_t len;
+  VEC(ld_plugin_symbol_resolution_t,heap) *resolutions;
+  
+  resolutions = lto_resolution_read (resolution_file, file->filename);
+
+  file_data = XCNEW (struct lto_file_decl_data);
+  file_data->file_name = file->filename;
+  file_data->fd = -1;
+  file_data->section_hash_table = lto_elf_build_section_table (file);
+  file_data->renaming_hash_table = lto_create_renaming_table ();
+
+  data = lto_get_section_data (file_data, LTO_section_decls, NULL, &len);
+  lto_read_decls (file_data, data, resolutions);
+  lto_free_section_data (file_data, LTO_section_decls, NULL, data, len);
+
+  return file_data;
+}
+
+#if HAVE_MMAP_FILE && HAVE_SYSCONF && defined _SC_PAGE_SIZE
+#define LTO_MMAP_IO 1
+#endif
+
+#if LTO_MMAP_IO
+/* Page size of machine is used for mmap and munmap calls.  */
+static size_t page_mask;
+#endif
+
+/* Get the section data of length LEN from FILENAME starting at
+   OFFSET.  The data segment must be freed by the caller when the
+   caller is finished.  Returns NULL if all was not well.  */
+
+static char *
+lto_read_section_data (struct lto_file_decl_data *file_data,
+		       intptr_t offset, size_t len)
+{
+  char *result;
+#if LTO_MMAP_IO
+  intptr_t computed_len;
+  intptr_t computed_offset;
+  intptr_t diff;
+#endif
+
+  if (file_data->fd == -1)
+    file_data->fd = open (file_data->file_name, O_RDONLY);
+
+  if (file_data->fd == -1)
+    return NULL;
+
+#if LTO_MMAP_IO
+  if (!page_mask)
+    {
+      size_t page_size = sysconf (_SC_PAGE_SIZE);
+      page_mask = ~(page_size - 1);
+    }
+
+  computed_offset = offset & page_mask;
+  diff = offset - computed_offset;
+  computed_len = len + diff;
+
+  result = (char *) mmap (NULL, computed_len, PROT_READ, MAP_PRIVATE,
+			  file_data->fd, computed_offset);
+  if (result == MAP_FAILED)
+    {
+      close (file_data->fd);
+      return NULL;
+    }
+
+  return result + diff;
+#else
+  result = (char *) xmalloc (len);
+  if (result == NULL)
+    {
+      close (file_data->fd);
+      return NULL;
+    }
+  if (lseek (file_data->fd, offset, SEEK_SET) != offset
+      || read (file_data->fd, result, len) != (ssize_t) len)
+    {
+      free (result);
+      close (file_data->fd);
+      return NULL;
+    }
+
+  return result;
+#endif
+}    
+
+
+/* Get the section data from FILE_DATA of SECTION_TYPE with NAME.
+   NAME will be NULL unless the section type is for a function
+   body.  */
+
+static const char *
+get_section_data (struct lto_file_decl_data *file_data,
+		      enum lto_section_type section_type,
+		      const char *name,
+		      size_t *len)
+{
+  htab_t section_hash_table = file_data->section_hash_table;
+  struct lto_section_slot *f_slot;
+  struct lto_section_slot s_slot;
+  const char *section_name = lto_get_section_name (section_type, name);
+  char *data = NULL;
+
+  *len = 0;
+  s_slot.name = section_name;
+  f_slot = (struct lto_section_slot *) htab_find (section_hash_table, &s_slot);
+  if (f_slot)
+    {
+      data = lto_read_section_data (file_data, f_slot->start, f_slot->len);
+      *len = f_slot->len;
+    }
+
+  free (CONST_CAST (char *, section_name));
+  return data;
+}
+
+
+/* Free the section data from FILE_DATA of SECTION_TYPE with NAME that
+   starts at OFFSET and has LEN bytes.  */
+
+static void
+free_section_data (struct lto_file_decl_data *file_data,
+		   enum lto_section_type section_type ATTRIBUTE_UNUSED,
+		   const char *name ATTRIBUTE_UNUSED,
+		   const char *offset, size_t len ATTRIBUTE_UNUSED)
+{
+#if LTO_MMAP_IO
+  intptr_t computed_len;
+  intptr_t computed_offset;
+  intptr_t diff;
+#endif
+
+  if (file_data->fd == -1)
+    return;
+
+#if LTO_MMAP_IO
+  computed_offset = ((intptr_t) offset) & page_mask;
+  diff = (intptr_t) offset - computed_offset;
+  computed_len = len + diff;
+
+  munmap ((caddr_t) computed_offset, computed_len);
+#else
+  free (CONST_CAST(char *, offset));
+#endif
+}
+
+/* Vector of all cgraph node sets. */
+static GTY (()) VEC(cgraph_node_set, gc) *lto_cgraph_node_sets;
+
+
+/* Group cgrah nodes by input files.  This is used mainly for testing
+   right now.  */
+
+static void
+lto_1_to_1_map (void)
+{
+  struct cgraph_node *node;
+  struct lto_file_decl_data *file_data;
+  struct pointer_map_t *pmap;
+  cgraph_node_set set;
+  void **slot;
+
+  timevar_push (TV_WHOPR_WPA);
+
+  lto_cgraph_node_sets = VEC_alloc (cgraph_node_set, gc, 1);
+
+  /* If the cgraph is empty, create one cgraph node set so that there is still
+     an output file for any variables that need to be exported in a DSO.  */
+  if (!cgraph_nodes)
+    {
+      set = cgraph_node_set_new ();
+      VEC_safe_push (cgraph_node_set, gc, lto_cgraph_node_sets, set);
+      goto finish;
+    }
+
+  pmap = pointer_map_create ();
+
+  for (node = cgraph_nodes; node; node = node->next)
+    {
+      /* We only need to partition the nodes that we read from the
+	 gimple bytecode files.  */
+      file_data = node->local.lto_file_data;
+      if (file_data == NULL)
+	continue;
+
+      slot = pointer_map_contains (pmap, file_data);
+      if (slot)
+	set = (cgraph_node_set) *slot;
+      else
+	{
+	  set = cgraph_node_set_new ();
+	  slot = pointer_map_insert (pmap, file_data);
+	  *slot = set;
+	  VEC_safe_push (cgraph_node_set, gc, lto_cgraph_node_sets, set);
+	}
+
+      cgraph_node_set_add (set, node);
+    }
+
+  pointer_map_destroy (pmap);
+
+finish:
+  timevar_pop (TV_WHOPR_WPA);
+
+  lto_stats.num_cgraph_partitions += VEC_length (cgraph_node_set, 
+						 lto_cgraph_node_sets);
+}
+
+
+/* Add inlined clone NODE and its master clone to SET, if NODE itself has
+   inlined callees, recursively add the callees.  */
+
+static void
+lto_add_inline_clones (cgraph_node_set set, struct cgraph_node *node,
+		       bitmap original_decls, bitmap inlined_decls)
+{
+   struct cgraph_node *callee;
+   struct cgraph_edge *edge;
+
+   cgraph_node_set_add (set, node);
+
+   if (!bitmap_bit_p (original_decls, DECL_UID (node->decl)))
+     bitmap_set_bit (inlined_decls, DECL_UID (node->decl));
+
+   /* Check to see if NODE has any inlined callee.  */
+   for (edge = node->callees; edge != NULL; edge = edge->next_callee)
+     {
+	callee = edge->callee;
+	if (callee->global.inlined_to != NULL)
+	  lto_add_inline_clones (set, callee, original_decls, inlined_decls);
+     }
+}
+
+/* Compute the transitive closure of inlining of SET based on the
+   information in the callgraph.  Returns a bitmap of decls that have
+   been inlined into SET indexed by UID.  */
+
+static bitmap
+lto_add_all_inlinees (cgraph_node_set set)
+{
+  cgraph_node_set_iterator csi;
+  struct cgraph_node *node;
+  bitmap original_nodes = lto_bitmap_alloc ();
+  bitmap original_decls = lto_bitmap_alloc ();
+  bitmap inlined_decls = lto_bitmap_alloc ();
+  bool changed;
+
+  /* We are going to iterate SET while adding to it, mark all original
+     nodes so that we only add node inlined to original nodes.  */
+  for (csi = csi_start (set); !csi_end_p (csi); csi_next (&csi))
+    {
+      bitmap_set_bit (original_nodes, csi_node (csi)->uid);
+      bitmap_set_bit (original_decls, DECL_UID (csi_node (csi)->decl));
+    }
+
+  /* Some of the original nodes might not be needed anymore.  
+     Remove them.  */
+  do
+    {
+      changed = false;
+      for (csi = csi_start (set); !csi_end_p (csi); csi_next (&csi))
+	{
+	  struct cgraph_node *inlined_to;
+	  node = csi_node (csi);
+
+	  /* NODE was not inlined.  We still need it.  */
+	  if (!node->global.inlined_to)
+	    continue;
+
+	  inlined_to = node->global.inlined_to;
+
+	  /* NODE should have only one caller.  */
+	  gcc_assert (!node->callers->next_caller);
+
+	  if (!bitmap_bit_p (original_nodes, inlined_to->uid))
+	    {
+	      bitmap_clear_bit (original_nodes, node->uid);
+	      cgraph_node_set_remove (set, node);
+	      changed = true;
+	    }
+	}
+    }
+  while (changed);
+
+  /* Transitively add to SET all the inline clones for every node that
+     has been inlined.  */
+  for (csi = csi_start (set); !csi_end_p (csi); csi_next (&csi))
+    {
+      node = csi_node (csi);
+      if (bitmap_bit_p (original_nodes, node->uid))
+	lto_add_inline_clones (set, node, original_decls, inlined_decls);
+    }
+
+  lto_bitmap_free (original_nodes);
+  lto_bitmap_free (original_decls);
+
+  return inlined_decls;
+}
+
+/* Owing to inlining, we may need to promote a file-scope variable
+   to a global variable.  Consider this case:
+
+   a.c:
+   static int var;
+
+   void
+   foo (void)
+   {
+     var++;
+   }
+
+   b.c:
+
+   extern void foo (void);
+
+   void
+   bar (void)
+   {
+     foo ();
+   }
+
+   If WPA inlines FOO inside BAR, then the static variable VAR needs to
+   be promoted to global because BAR and VAR may be in different LTRANS
+   files. */
+
+/* This struct keeps track of states used in globalization.  */
+
+typedef struct
+{
+  /* Current cgraph node set.  */  
+  cgraph_node_set set;
+
+  /* Function DECLs of cgraph nodes seen.  */
+  bitmap seen_node_decls;
+
+  /* Use in walk_tree to avoid multiple visits of a node.  */
+  struct pointer_set_t *visited;
+
+  /* static vars in this set.  */
+  bitmap static_vars_in_set;
+
+  /* static vars in all previous set.  */
+  bitmap all_static_vars;
+
+  /* all vars in all previous set.  */
+  bitmap all_vars;
+} globalize_context_t;
+
+/* Callback for walk_tree.  Examine the tree pointer to by TP and see if
+   if its a file-scope static variable of function that need to be turned
+   into a global.  */
+
+static tree
+globalize_cross_file_statics (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
+			      void *data)
+{
+  globalize_context_t *context = (globalize_context_t *) data;
+  tree t = *tp;
+
+  if (t == NULL_TREE)
+    return NULL;
+
+  /* The logic for globalization of VAR_DECLs and FUNCTION_DECLs are
+     different.  For functions, we can simply look at the cgraph node sets
+     to tell if there are references to static functions outside the set.
+     The cgraph node sets do not keep track of vars, we need to traverse
+     the trees to determine what vars need to be globalized.  */
+  if (TREE_CODE (t) == VAR_DECL)
+    {
+      if (!TREE_PUBLIC (t))
+	{
+	  /* This file-scope static variable is reachable from more
+	     that one set.  Make it global but with hidden visibility
+	     so that we do not export it in dynamic linking.  */
+	  if (bitmap_bit_p (context->all_static_vars, DECL_UID (t)))
+	    {
+	      TREE_PUBLIC (t) = 1;
+	      DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
+	    }
+	  bitmap_set_bit (context->static_vars_in_set, DECL_UID (t));
+	}
+      bitmap_set_bit (context->all_vars, DECL_UID (t));
+      walk_tree (&DECL_INITIAL (t), globalize_cross_file_statics, context,
+		 context->visited);
+    }
+  else if (TREE_CODE (t) == FUNCTION_DECL && !TREE_PUBLIC (t))
+    {
+      if (!cgraph_node_in_set_p (cgraph_node (t), context->set))
+	{
+	  /* This file-scope static function is reachable from a set
+	     which does not contain the function DECL.  Make it global
+	     but with hidden visibility.  */
+	  TREE_PUBLIC (t) = 1;
+	  DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
+	}
+    }
+
+  return NULL; 
+}
+
+/* Helper of lto_scan_statics_in_cgraph_node below.  Scan TABLE for
+   static decls that may be used in more than one LTRANS file.
+   CONTEXT is a globalize_context_t for storing scanning states.  */
+
+static void
+lto_scan_statics_in_ref_table (struct lto_tree_ref_table *table,
+			       globalize_context_t *context)
+{
+  unsigned i;
+
+  for (i = 0; i < table->size; i++)
+    walk_tree (&table->trees[i], globalize_cross_file_statics, context,
+	       context->visited);
+}
+
+/* Promote file-scope decl reachable from NODE if necessary to global.
+   CONTEXT is a globalize_context_t storing scanning states.  */
+
+static void
+lto_scan_statics_in_cgraph_node (struct cgraph_node *node,
+				 globalize_context_t *context)
+{
+  struct lto_in_decl_state *state;
+  
+  /* Do nothing if NODE has no function body.  */
+  if (!node->analyzed)
+    return;
+  
+  /* Return if the DECL of nodes has been visited before.  */
+  if (bitmap_bit_p (context->seen_node_decls, DECL_UID (node->decl)))
+    return;
+
+  bitmap_set_bit (context->seen_node_decls, DECL_UID (node->decl));
+
+  state = lto_get_function_in_decl_state (node->local.lto_file_data,
+					  node->decl);
+  gcc_assert (state);
+
+  lto_scan_statics_in_ref_table (&state->streams[LTO_DECL_STREAM_VAR_DECL],
+				 context);
+  lto_scan_statics_in_ref_table (&state->streams[LTO_DECL_STREAM_FN_DECL],
+				 context);
+}
+
+/* Scan all global variables that we have not yet seen so far.  CONTEXT
+   is a globalize_context_t storing scanning states.  */
+
+static void
+lto_scan_statics_in_remaining_global_vars (globalize_context_t *context)
+{
+  tree var, var_context;
+  struct varpool_node *vnode;
+
+  FOR_EACH_STATIC_VARIABLE (vnode)
+    {
+      var = vnode->decl;
+      var_context = DECL_CONTEXT (var);
+      if (TREE_STATIC (var)
+	  && TREE_PUBLIC (var)
+          && (!var_context || TREE_CODE (var_context) != FUNCTION_DECL)
+          && !bitmap_bit_p (context->all_vars, DECL_UID (var)))
+	walk_tree (&var, globalize_cross_file_statics, context,
+		   context->visited);
+    }
+}
+
+/* Find out all static decls that need to be promoted to global because
+   of cross file sharing.  This function must be run in the WPA mode after
+   all inlinees are added.  */
+
+static void
+lto_promote_cross_file_statics (void)
+{
+  unsigned i, n_sets;
+  cgraph_node_set set;
+  cgraph_node_set_iterator csi;
+  globalize_context_t context;
+
+  memset (&context, 0, sizeof (context));
+  context.all_vars = lto_bitmap_alloc ();
+  context.all_static_vars = lto_bitmap_alloc ();
+
+  n_sets = VEC_length (cgraph_node_set, lto_cgraph_node_sets);
+  for (i = 0; i < n_sets; i++)
+    {
+      set = VEC_index (cgraph_node_set, lto_cgraph_node_sets, i);
+      context.set = set;
+      context.visited = pointer_set_create ();
+      context.static_vars_in_set = lto_bitmap_alloc ();
+      context.seen_node_decls = lto_bitmap_alloc ();
+
+      for (csi = csi_start (set); !csi_end_p (csi); csi_next (&csi))
+	lto_scan_statics_in_cgraph_node (csi_node (csi), &context);
+
+      if (i == n_sets - 1)
+        lto_scan_statics_in_remaining_global_vars (&context);
+
+      bitmap_ior_into (context.all_static_vars, context.static_vars_in_set);
+
+      pointer_set_destroy (context.visited);
+      lto_bitmap_free (context.static_vars_in_set);
+      lto_bitmap_free (context.seen_node_decls);
+    }
+
+  lto_bitmap_free (context.all_vars);
+  lto_bitmap_free (context.all_static_vars);
+}
+
+
+/* Given a file name FNAME, return a string with FNAME prefixed with '*'.  */
+
+static char *
+prefix_name_with_star (const char *fname)
+{
+  char *star_fname;
+  size_t len;
+  
+  len = strlen (fname) + 1 + 1;
+  star_fname = XNEWVEC (char, len);
+  snprintf (star_fname, len, "*%s", fname);
+
+  return star_fname;
+}
+
+
+/* Return a copy of FNAME without the .o extension.  */
+
+static char *
+strip_extension (const char *fname)
+{
+  char *s = XNEWVEC (char, strlen (fname) - 2 + 1);
+  gcc_assert (strstr (fname, ".o"));
+  snprintf (s, strlen (fname) - 2 + 1, "%s", fname);
+
+  return s;
+}
+
+
+/* Return a file name associated with cgraph node set SET.  This may
+   be a new temporary file name if SET needs to be processed by
+   LTRANS, or the original file name if all the nodes in SET belong to
+   the same input file.  */
+
+static char *
+get_filename_for_set (cgraph_node_set set)
+{
+  char *fname = NULL;
+  static const size_t max_fname_len = 100;
+
+  if (cgraph_node_set_needs_ltrans_p (set))
+    {
+      /* Create a new temporary file to store SET.  To facilitate
+	 debugging, use file names from SET as part of the new
+	 temporary file name.  */
+      cgraph_node_set_iterator si;
+      struct pointer_set_t *pset = pointer_set_create ();
+      for (si = csi_start (set); !csi_end_p (si); csi_next (&si))
+	{
+	  struct cgraph_node *n = csi_node (si);
+	  const char *node_fname;
+	  char *f;
+
+	  /* Don't use the same file name more than once.  */
+	  if (pointer_set_insert (pset, n->local.lto_file_data))
+	    continue;
+
+	  /* The first file name found in SET determines the output
+	     directory.  For the remaining files, we use their
+	     base names.  */
+	  node_fname = n->local.lto_file_data->file_name;
+	  if (fname == NULL)
+	    {
+	      fname = strip_extension (node_fname);
+	      continue;
+	    }
+
+	  f = strip_extension (lbasename (node_fname));
+
+	  /* If the new name causes an excessively long file name,
+	     make the last component "___" to indicate overflow.  */
+	  if (strlen (fname) + strlen (f) > max_fname_len - 3)
+	    {
+	      fname = reconcat (fname, fname, "___", NULL);
+	      break;
+	    }
+	  else
+	    {
+	      fname = reconcat (fname, fname, "_", f, NULL);
+	      free (f);
+	    }
+	}
+
+      pointer_set_destroy (pset);
+
+      /* Add the extension .wpa.o to indicate that this file has been
+	 produced by WPA.  */
+      fname = reconcat (fname, fname, ".wpa.o", NULL);
+      gcc_assert (fname);
+    }
+  else
+    {
+      /* Since SET does not need to be processed by LTRANS, use
+	 the original file name and mark it with a '*' prefix so that
+	 lto_execute_ltrans knows not to process it.  */
+      cgraph_node_set_iterator si = csi_start (set);
+      struct cgraph_node *first = csi_node (si);
+      fname = prefix_name_with_star (first->local.lto_file_data->file_name);
+    }
+
+  return fname;
+}
+
+static lto_file *current_lto_file;
+
+
+/* Write all output files in WPA mode.  Returns a NULL-terminated array of
+   output file names.  */
+
+static char **
+lto_wpa_write_files (void)
+{
+  char **output_files;
+  unsigned i, n_sets, last_out_file_ix, num_out_files;
+  lto_file *file;
+  cgraph_node_set set;
+  bitmap decls;
+  VEC(bitmap,heap) *inlined_decls = NULL;
+
+  timevar_push (TV_WHOPR_WPA);
+
+  /* Include all inlined functions and determine what sets need to be
+     compiled by LTRANS.  After this loop, only those sets that
+     contain callgraph nodes from more than one file will need to be
+     compiled by LTRANS.  */
+  for (i = 0; VEC_iterate (cgraph_node_set, lto_cgraph_node_sets, i, set); i++)
+    {
+      decls = lto_add_all_inlinees (set);
+      VEC_safe_push (bitmap, heap, inlined_decls, decls);
+      lto_stats.num_output_cgraph_nodes += VEC_length (cgraph_node_ptr,
+						       set->nodes);
+    }
+
+  /* After adding all inlinees, find out statics that need to be promoted
+     to globals because of cross-file inlining.  */
+  lto_promote_cross_file_statics ();
+
+  timevar_pop (TV_WHOPR_WPA);
+
+  timevar_push (TV_WHOPR_WPA_IO);
+
+  /* The number of output files depends on the number of input files
+     and how many callgraph node sets we create.  Reserve enough space
+     for the maximum of these two.  */
+  num_out_files = MAX (VEC_length (cgraph_node_set, lto_cgraph_node_sets),
+                       num_in_fnames);
+  output_files = XNEWVEC (char *, num_out_files + 1);
+
+  n_sets = VEC_length (cgraph_node_set, lto_cgraph_node_sets);
+  for (i = 0; i < n_sets; i++)
+    {
+      char *temp_filename;
+
+      set = VEC_index (cgraph_node_set, lto_cgraph_node_sets, i);
+      temp_filename = get_filename_for_set (set);
+      output_files[i] = temp_filename;
+
+      if (cgraph_node_set_needs_ltrans_p (set))
+	{
+	  /* Write all the nodes in SET to TEMP_FILENAME.  */
+	  file = lto_elf_file_open (temp_filename, true);
+	  if (!file)
+	    fatal_error ("lto_elf_file_open() failed");
+
+	  lto_set_current_out_file (file);
+	  lto_new_extern_inline_states ();
+
+	  decls = VEC_index (bitmap, inlined_decls, i);
+	  lto_force_functions_extern_inline (decls);
+
+	  ipa_write_summaries_of_cgraph_node_set (set);
+	  lto_delete_extern_inline_states ();
+
+	  lto_set_current_out_file (NULL);
+	  lto_elf_file_close (file);
+	}
+    }
+
+  last_out_file_ix = n_sets;
+
+  lto_stats.num_output_files += n_sets;
+
+  output_files[last_out_file_ix] = NULL;
+
+  for (i = 0; VEC_iterate (bitmap, inlined_decls, i, decls); i++)
+    lto_bitmap_free (decls);
+  VEC_free (bitmap, heap, inlined_decls);
+
+  timevar_pop (TV_WHOPR_WPA_IO);
+
+  return output_files;
+}
+
+
+/* Perform local transformations (LTRANS) on the files in the NULL-terminated
+   FILES array.  These should have been written previously by
+   lto_wpa_write_files ().  Transformations are performed via executing
+   COLLECT_GCC for reach file.  */
+
+static void
+lto_execute_ltrans (char *const *files)
+{
+  struct pex_obj *pex;
+  const char *collect_gcc_options, *collect_gcc;
+  struct obstack env_obstack;
+  const char **argv;
+  const char **argv_ptr;
+  const char *errmsg;
+  size_t i, j;
+  int err;
+  int status;
+  FILE *ltrans_output_list_stream = NULL;
+
+  timevar_push (TV_WHOPR_WPA_LTRANS_EXEC);
+
+  /* Get the driver and options.  */
+  collect_gcc = getenv ("COLLECT_GCC");
+  if (!collect_gcc)
+    fatal_error ("environment variable COLLECT_GCC must be set");
+
+  /* Set the CFLAGS environment variable.  */
+  collect_gcc_options = getenv ("COLLECT_GCC_OPTIONS");
+  if (!collect_gcc_options)
+    fatal_error ("environment variable COLLECT_GCC_OPTIONS must be set");
+
+  /* Count arguments.  */
+  i = 0;
+  for (j = 0; collect_gcc_options[j] != '\0'; ++j)
+    if (collect_gcc_options[j] == '\'')
+      ++i;
+
+  if (i % 2 != 0)
+    fatal_error ("malformed COLLECT_GCC_OPTIONS");
+
+  /* Initalize the arguments for the LTRANS driver.  */
+  argv = XNEWVEC (const char *, 8 + i / 2);
+  argv_ptr = argv;
+  *argv_ptr++ = collect_gcc;
+  *argv_ptr++ = "-xlto";
+  for (j = 0; collect_gcc_options[j] != '\0'; ++j)
+    if (collect_gcc_options[j] == '\'')
+      {
+	char *option;
+
+	++j;
+	i = j;
+	while (collect_gcc_options[j] != '\'')
+	  ++j;
+	obstack_init (&env_obstack);
+	obstack_grow (&env_obstack, &collect_gcc_options[i], j - i);
+	obstack_1grow (&env_obstack, 0);
+	option = XOBFINISH (&env_obstack, char *);
+
+	/* LTRANS does not need -fwpa nor -fltrans-*.  */
+	if (strncmp (option, "-fwpa", 5) != 0
+	    && strncmp (option, "-fltrans-", 9) != 0)
+	  *argv_ptr++ = option;
+      }
+  *argv_ptr++ = "-fltrans";
+
+  /* Open the LTRANS output list.  */
+  if (ltrans_output_list)
+    {
+      ltrans_output_list_stream = fopen (ltrans_output_list, "w");
+      if (ltrans_output_list_stream == NULL)
+	error ("opening LTRANS output list %s: %m", ltrans_output_list);
+    }
+
+  for (i = 0; files[i]; ++i)
+    {
+      size_t len;
+
+      /* If the file is prefixed with a '*', it means that we do not
+	 need to re-compile it with LTRANS because it has not been
+	 modified by WPA.  Skip it from the command line to
+	 lto_execute_ltrans, but add it to ltrans_output_list_stream
+	 so it is linked after we are done.  */
+      if (files[i][0] == '*')
+	{
+	  size_t len = strlen (files[i]) - 1;
+	  if (ltrans_output_list_stream)
+	    if (fwrite (&files[i][1], 1, len, ltrans_output_list_stream) < len
+		|| fwrite ("\n", 1, 1, ltrans_output_list_stream) < 1)
+	      error ("writing to LTRANS output list %s: %m",
+		     ltrans_output_list);
+	}
+      else
+	{
+	  char *output_name;
+
+	  /* Otherwise, add FILES[I] to lto_execute_ltrans command line
+	     and add the resulting file to LTRANS output list.  */
+
+	  /* Replace the .o suffix with a .ltrans.o suffix and write
+	     the resulting name to the LTRANS output list.  */
+	  obstack_init (&env_obstack);
+	  obstack_grow (&env_obstack, files[i], strlen (files[i]) - 2);
+	  obstack_grow (&env_obstack, ".ltrans.o", sizeof (".ltrans.o"));
+	  output_name = XOBFINISH (&env_obstack, char *);
+	  if (ltrans_output_list_stream)
+	    {
+	      len = strlen (output_name);
+
+	      if (fwrite (output_name, 1, len, ltrans_output_list_stream) < len
+		  || fwrite ("\n", 1, 1, ltrans_output_list_stream) < 1)
+		error ("writing to LTRANS output list %s: %m",
+		       ltrans_output_list);
+	    }
+
+	  argv_ptr[0] = "-o";
+	  argv_ptr[1] = output_name;
+	  argv_ptr[2] = files[i];
+	  argv_ptr[3] = NULL;
+
+	  /* Execute the driver.  */
+	  pex = pex_init (0, "lto1", NULL);
+	  if (pex == NULL)
+	    fatal_error ("pex_init failed: %s", xstrerror (errno));
+
+	  errmsg = pex_run (pex, PEX_LAST | PEX_SEARCH, argv[0],
+			    CONST_CAST (char **, argv), NULL, NULL, &err);
+	  if (errmsg)
+	    fatal_error ("%s: %s", errmsg, xstrerror (err));
+
+	  if (!pex_get_status (pex, 1, &status))
+	    fatal_error ("can't get program status: %s", xstrerror (errno));
+
+	  if (status)
+	    {
+	      if (WIFSIGNALED (status))
+		{
+		  int sig = WTERMSIG (status);
+		  fatal_error ("%s terminated with signal %d [%s]%s",
+			       argv[0], sig, strsignal (sig),
+			       WCOREDUMP (status) ? ", core dumped" : "");
+		}
+	      else
+		fatal_error ("%s terminated with status %d", argv[0], status);
+	    }
+
+	  pex_free (pex);
+	}
+    }
+
+  /* Close the LTRANS output list.  */
+  if (ltrans_output_list_stream && fclose (ltrans_output_list_stream))
+    error ("closing LTRANS output list %s: %m", ltrans_output_list);
+
+  obstack_free (&env_obstack, NULL);
+  free (argv);
+
+  timevar_pop (TV_WHOPR_WPA_LTRANS_EXEC);
+}
+
+
+typedef struct {
+  struct pointer_set_t *free_list;
+  struct pointer_set_t *seen;
+} lto_fixup_data_t;
+
+#define LTO_FIXUP_SUBTREE(t) \
+  do \
+    walk_tree (&(t), lto_fixup_tree, data, NULL); \
+  while (0)
+
+#define LTO_REGISTER_TYPE_AND_FIXUP_SUBTREE(t) \
+  do \
+    { \
+      if (t) \
+	(t) = gimple_register_type (t); \
+      walk_tree (&(t), lto_fixup_tree, data, NULL); \
+    } \
+  while (0)
+
+static tree lto_fixup_tree (tree *, int *, void *);
+
+/* Return true if T does not need to be fixed up recursively.  */
+
+static inline bool
+no_fixup_p (tree t)
+{
+  return (t == NULL
+	  || CONSTANT_CLASS_P (t)
+	  || TREE_CODE (t) == IDENTIFIER_NODE);
+}
+
+/* Fix up fields of a tree_common T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_common (tree t, void *data)
+{
+  /* The following re-creates the TYPE_REFERENCE_TO and TYPE_POINTER_TO
+     lists.  We do not stream TYPE_REFERENCE_TO, TYPE_POINTER_TO or
+     TYPE_NEXT_PTR_TO and TYPE_NEXT_REF_TO.
+     First remove us from any pointer list we are on.  */
+  if (TREE_CODE (t) == POINTER_TYPE)
+    {
+      if (TYPE_POINTER_TO (TREE_TYPE (t)) == t)
+	TYPE_POINTER_TO (TREE_TYPE (t)) = TYPE_NEXT_PTR_TO (t);
+      else
+	{
+	  tree tem = TYPE_POINTER_TO (TREE_TYPE (t));
+	  while (tem && TYPE_NEXT_PTR_TO (tem) != t)
+	    tem = TYPE_NEXT_PTR_TO (tem);
+	  if (tem)
+	    TYPE_NEXT_PTR_TO (tem) = TYPE_NEXT_PTR_TO (t);
+	}
+      TYPE_NEXT_PTR_TO (t) = NULL_TREE;
+    }
+  else if (TREE_CODE (t) == REFERENCE_TYPE)
+    {
+      if (TYPE_REFERENCE_TO (TREE_TYPE (t)) == t)
+	TYPE_REFERENCE_TO (TREE_TYPE (t)) = TYPE_NEXT_REF_TO (t);
+      else
+	{
+	  tree tem = TYPE_REFERENCE_TO (TREE_TYPE (t));
+	  while (tem && TYPE_NEXT_REF_TO (tem) != t)
+	    tem = TYPE_NEXT_REF_TO (tem);
+	  if (tem)
+	    TYPE_NEXT_REF_TO (tem) = TYPE_NEXT_REF_TO (t);
+	}
+      TYPE_NEXT_REF_TO (t) = NULL_TREE;
+    }
+
+  /* Fixup our type.  */
+  LTO_REGISTER_TYPE_AND_FIXUP_SUBTREE (TREE_TYPE (t));
+
+  /* Second put us on the list of pointers of the new pointed-to type
+     if we are a main variant.  This is done in lto_fixup_type after
+     fixing up our main variant.  */
+
+  /* This is not very efficient because we cannot do tail-recursion with
+     a long chain of trees. */
+  LTO_FIXUP_SUBTREE (TREE_CHAIN (t));
+}
+
+/* Fix up fields of a decl_minimal T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_decl_minimal (tree t, void *data)
+{
+  lto_fixup_common (t, data);
+  LTO_FIXUP_SUBTREE (DECL_NAME (t));
+  LTO_FIXUP_SUBTREE (DECL_CONTEXT (t));
+}
+
+/* Fix up fields of a decl_common T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_decl_common (tree t, void *data)
+{
+  lto_fixup_decl_minimal (t, data);
+  LTO_FIXUP_SUBTREE (DECL_SIZE (t));
+  LTO_FIXUP_SUBTREE (DECL_SIZE_UNIT (t));
+  LTO_FIXUP_SUBTREE (DECL_INITIAL (t));
+  LTO_FIXUP_SUBTREE (DECL_ATTRIBUTES (t));
+  LTO_FIXUP_SUBTREE (DECL_ABSTRACT_ORIGIN (t));
+}
+
+/* Fix up fields of a decl_with_vis T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_decl_with_vis (tree t, void *data)
+{
+  lto_fixup_decl_common (t, data);
+
+  /* Accessor macro has side-effects, use field-name here. */
+  LTO_FIXUP_SUBTREE (t->decl_with_vis.assembler_name);
+
+  gcc_assert (no_fixup_p (DECL_SECTION_NAME (t)));
+}
+
+/* Fix up fields of a decl_non_common T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_decl_non_common (tree t, void *data)
+{
+  lto_fixup_decl_with_vis (t, data);
+  LTO_FIXUP_SUBTREE (DECL_ARGUMENT_FLD (t));
+  LTO_FIXUP_SUBTREE (DECL_RESULT_FLD (t));
+  LTO_FIXUP_SUBTREE (DECL_VINDEX (t));
+
+  /* SAVED_TREE should not cleared by now.  Also no accessor for base type. */
+  gcc_assert (no_fixup_p (t->decl_non_common.saved_tree));
+}
+
+/* Fix up fields of a decl_non_common T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_function (tree t, void *data)
+{
+  lto_fixup_decl_non_common (t, data);
+  LTO_FIXUP_SUBTREE (DECL_FUNCTION_PERSONALITY (t));
+}
+
+/* Fix up fields of a field_decl T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_field_decl (tree t, void *data)
+{
+  lto_fixup_decl_common (t, data);
+  gcc_assert (no_fixup_p (DECL_FIELD_OFFSET (t)));
+  LTO_FIXUP_SUBTREE (DECL_BIT_FIELD_TYPE (t));
+  LTO_FIXUP_SUBTREE (DECL_QUALIFIER (t));
+  gcc_assert (no_fixup_p (DECL_FIELD_BIT_OFFSET (t)));
+  LTO_FIXUP_SUBTREE (DECL_FCONTEXT (t));
+}
+
+/* Fix up fields of a type T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_type (tree t, void *data)
+{
+  tree tem, mv;
+
+  lto_fixup_common (t, data);
+  LTO_FIXUP_SUBTREE (TYPE_CACHED_VALUES (t));
+  LTO_FIXUP_SUBTREE (TYPE_SIZE (t));
+  LTO_FIXUP_SUBTREE (TYPE_SIZE_UNIT (t));
+  LTO_FIXUP_SUBTREE (TYPE_ATTRIBUTES (t));
+  LTO_FIXUP_SUBTREE (TYPE_NAME (t));
+
+  /* Accessors are for derived node types only. */
+  if (!POINTER_TYPE_P (t))
+    LTO_FIXUP_SUBTREE (t->type.minval);
+  LTO_FIXUP_SUBTREE (t->type.maxval);
+
+  /* Accessor is for derived node types only. */
+  LTO_FIXUP_SUBTREE (t->type.binfo);
+
+  LTO_REGISTER_TYPE_AND_FIXUP_SUBTREE (TYPE_CONTEXT (t));
+  LTO_REGISTER_TYPE_AND_FIXUP_SUBTREE (TYPE_CANONICAL (t));
+
+  /* The following re-creates proper variant lists while fixing up
+     the variant leaders.  We do not stream TYPE_NEXT_VARIANT so the
+     variant list state before fixup is broken.  */
+
+  /* Remove us from our main variant list if we are not the variant leader.  */
+  if (TYPE_MAIN_VARIANT (t) != t)
+    {
+      tem = TYPE_MAIN_VARIANT (t);
+      while (tem && TYPE_NEXT_VARIANT (tem) != t)
+	tem = TYPE_NEXT_VARIANT (tem);
+      if (tem)
+	TYPE_NEXT_VARIANT (tem) = TYPE_NEXT_VARIANT (t);
+      TYPE_NEXT_VARIANT (t) = NULL_TREE;
+    }
+
+  /* Query our new main variant.  */
+  mv = gimple_register_type (TYPE_MAIN_VARIANT (t));
+
+  /* If we were the variant leader and we get replaced ourselves drop
+     all variants from our list.  */
+  if (TYPE_MAIN_VARIANT (t) == t
+      && mv != t)
+    {
+      tem = t;
+      while (tem)
+	{
+	  tree tem2 = TYPE_NEXT_VARIANT (tem);
+	  TYPE_NEXT_VARIANT (tem) = NULL_TREE;
+	  tem = tem2;
+	}
+    }
+
+  /* If we are not our own variant leader link us into our new leaders
+     variant list.  */
+  if (mv != t)
+    {
+      TYPE_NEXT_VARIANT (t) = TYPE_NEXT_VARIANT (mv);
+      TYPE_NEXT_VARIANT (mv) = t;
+    }
+
+  /* Finally adjust our main variant and fix it up.  */
+  TYPE_MAIN_VARIANT (t) = mv;
+  LTO_FIXUP_SUBTREE (TYPE_MAIN_VARIANT (t));
+
+  /* As the second step of reconstructing the pointer chains put us
+     on the list of pointers of the new pointed-to type
+     if we are a main variant.  See lto_fixup_common for the first step.  */
+  if (TREE_CODE (t) == POINTER_TYPE
+      && TYPE_MAIN_VARIANT (t) == t)
+    {
+      TYPE_NEXT_PTR_TO (t) = TYPE_POINTER_TO (TREE_TYPE (t));
+      TYPE_POINTER_TO (TREE_TYPE (t)) = t;
+    }
+  else if (TREE_CODE (t) == REFERENCE_TYPE
+	   && TYPE_MAIN_VARIANT (t) == t)
+    {
+      TYPE_NEXT_REF_TO (t) = TYPE_REFERENCE_TO (TREE_TYPE (t));
+      TYPE_REFERENCE_TO (TREE_TYPE (t)) = t;
+    }
+}
+
+/* Fix up fields of a BINFO T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_binfo (tree t, void *data)
+{
+  unsigned HOST_WIDE_INT i, n;
+  tree base, saved_base;
+
+  lto_fixup_common (t, data);
+  gcc_assert (no_fixup_p (BINFO_OFFSET (t)));
+  LTO_FIXUP_SUBTREE (BINFO_VTABLE (t));
+  LTO_FIXUP_SUBTREE (BINFO_VIRTUALS (t));
+  LTO_FIXUP_SUBTREE (BINFO_VPTR_FIELD (t));
+  n = VEC_length (tree, BINFO_BASE_ACCESSES (t));
+  for (i = 0; i < n; i++)
+    {
+      saved_base = base = BINFO_BASE_ACCESS (t, i);
+      LTO_FIXUP_SUBTREE (base);
+      if (base != saved_base)
+	VEC_replace (tree, BINFO_BASE_ACCESSES (t), i, base);
+    }
+  LTO_FIXUP_SUBTREE (BINFO_INHERITANCE_CHAIN (t));
+  LTO_FIXUP_SUBTREE (BINFO_SUBVTT_INDEX (t));
+  LTO_FIXUP_SUBTREE (BINFO_VPTR_INDEX (t));
+  n = BINFO_N_BASE_BINFOS (t);
+  for (i = 0; i < n; i++)
+    {
+      saved_base = base = BINFO_BASE_BINFO (t, i);
+      LTO_FIXUP_SUBTREE (base);
+      if (base != saved_base)
+	VEC_replace (tree, BINFO_BASE_BINFOS (t), i, base);
+    }
+}
+
+/* Fix up fields of a CONSTRUCTOR T.  DATA points to fix-up states.  */
+
+static void
+lto_fixup_constructor (tree t, void *data)
+{
+  unsigned HOST_WIDE_INT idx;
+  constructor_elt *ce;
+
+  LTO_REGISTER_TYPE_AND_FIXUP_SUBTREE (TREE_TYPE (t));
+
+  for (idx = 0;
+       VEC_iterate(constructor_elt, CONSTRUCTOR_ELTS (t), idx, ce);
+       idx++)
+    {
+      LTO_FIXUP_SUBTREE (ce->index);
+      LTO_FIXUP_SUBTREE (ce->value);
+    }
+}
+
+/* A walk_tree callback used by lto_fixup_state. TP is the pointer to the
+   current tree. WALK_SUBTREES indicates if the subtrees will be walked.
+   DATA is a pointer set to record visited nodes. */
+
+static tree
+lto_fixup_tree (tree *tp, int *walk_subtrees, void *data)
+{
+  tree t;
+  lto_fixup_data_t *fixup_data = (lto_fixup_data_t *) data;
+  tree prevailing;
+
+  t = *tp;
+  *walk_subtrees = 0;
+  if (pointer_set_contains (fixup_data->seen, t))
+    return NULL;
+
+  if (TREE_CODE (t) == VAR_DECL || TREE_CODE (t) == FUNCTION_DECL)
+    {
+      prevailing = lto_symtab_prevailing_decl (t);
+
+      if (t != prevailing)
+	{
+	  if (TREE_CODE (t) == FUNCTION_DECL
+	      && TREE_NOTHROW (prevailing) != TREE_NOTHROW (t))
+	    {
+	      /* If the prevailing definition does not throw but the
+		 declaration (T) was considered throwing, then we
+		 simply add PREVAILING to the list of throwing
+		 functions.  However, if the opposite is true, then
+		 the call to PREVAILING was generated assuming that
+		 the function didn't throw, which means that CFG
+		 cleanup may have removed surrounding try/catch
+		 regions.
+
+		 Note that we currently accept these cases even when
+		 they occur within a single file.  It's certainly a
+		 user error, but we silently allow the compiler to
+		 remove surrounding try/catch regions.  Perhaps we
+		 could emit a warning here, instead of silently
+		 accepting the conflicting declaration.  */
+	      if (TREE_NOTHROW (prevailing))
+		lto_mark_nothrow_fndecl (prevailing);
+	    }
+
+	  pointer_set_insert (fixup_data->free_list, t);
+
+	   /* Also replace t with prevailing defintion.  We don't want to
+	      insert the other defintion in the seen set as we want to
+	      replace all instances of it.  */
+	  *tp = prevailing;
+	  t = prevailing;
+	}
+    }
+  else if (TYPE_P (t))
+    {
+      /* Replace t with the prevailing type.  We don't want to insert the
+         other type in the seen set as we want to replace all instances of it.  */
+      t = gimple_register_type (t);
+      *tp = t;
+    }
+
+  if (pointer_set_insert (fixup_data->seen, t))
+    return NULL;
+
+  /* walk_tree does not visit all reachable nodes that need to be fixed up.
+     Hence we do special processing here for those kind of nodes. */
+  switch (TREE_CODE (t))
+    {
+    case FIELD_DECL:
+      lto_fixup_field_decl (t, data);
+      break;
+
+    case LABEL_DECL:
+    case CONST_DECL:
+    case PARM_DECL:
+    case RESULT_DECL:
+    case IMPORTED_DECL:
+      lto_fixup_decl_common (t, data);
+      break;
+
+    case VAR_DECL:
+      lto_fixup_decl_with_vis (t, data);
+      break;	
+
+    case TYPE_DECL:
+      lto_fixup_decl_non_common (t, data);
+      break;
+
+    case FUNCTION_DECL:
+      lto_fixup_function (t, data);
+      break;
+
+    case TREE_BINFO:
+      lto_fixup_binfo (t, data);
+      break;
+
+    default:
+      if (TYPE_P (t))
+	lto_fixup_type (t, data);
+      else if (TREE_CODE (t) == CONSTRUCTOR)
+	lto_fixup_constructor (t, data);
+      else if (CONSTANT_CLASS_P (t))
+	LTO_REGISTER_TYPE_AND_FIXUP_SUBTREE (TREE_TYPE (t));
+      else if (EXPR_P (t))
+	{
+	  /* walk_tree only handles TREE_OPERANDs. Do the rest here.  */
+	  lto_fixup_common (t, data);
+	  LTO_FIXUP_SUBTREE (t->exp.block);
+	  *walk_subtrees = 1;
+	}
+      else
+	{
+	  /* Let walk_tree handle sub-trees.  */
+	  *walk_subtrees = 1;
+	}
+    }
+
+  return NULL;
+}
+
+/* Helper function of lto_fixup_decls. Walks the var and fn streams in STATE,
+   replaces var and function decls with the corresponding prevailing def and
+   records the old decl in the free-list in DATA. We also record visted nodes
+   in the seen-set in DATA to avoid multiple visit for nodes that need not
+   to be replaced.  */
+
+static void
+lto_fixup_state (struct lto_in_decl_state *state, lto_fixup_data_t *data)
+{
+  unsigned i, si;
+  struct lto_tree_ref_table *table;
+
+  /* Although we only want to replace FUNCTION_DECLs and VAR_DECLs,
+     we still need to walk from all DECLs to find the reachable
+     FUNCTION_DECLs and VAR_DECLs.  */
+  for (si = 0; si < LTO_N_DECL_STREAMS; si++)
+    {
+      table = &state->streams[si];
+      for (i = 0; i < table->size; i++)
+	walk_tree (table->trees + i, lto_fixup_tree, data, NULL);
+    }
+}
+
+/* A callback of htab_traverse. Just extract a state from SLOT and the
+   lto_fixup_data_t object from AUX and calls lto_fixup_state. */
+
+static int
+lto_fixup_state_aux (void **slot, void *aux)
+{
+  struct lto_in_decl_state *state = (struct lto_in_decl_state *) *slot;
+  lto_fixup_state (state, (lto_fixup_data_t *) aux);
+  return 1;
+}
+
+/* A callback to pointer_set_traverse. Frees the tree pointed by p. Removes
+   from it from the UID -> DECL mapping. */
+
+static bool
+free_decl (const void *p, void *data ATTRIBUTE_UNUSED)
+{
+  const_tree ct = (const_tree) p;
+  tree t = CONST_CAST_TREE (ct);
+
+  lto_symtab_clear_resolution (t);
+
+  return true;
+}
+
+/* Fix the decls from all FILES. Replaces each decl with the corresponding
+   prevailing one.  */
+
+static void
+lto_fixup_decls (struct lto_file_decl_data **files)
+{
+  unsigned int i;
+  tree decl;
+  struct pointer_set_t *free_list = pointer_set_create ();
+  struct pointer_set_t *seen = pointer_set_create ();
+  lto_fixup_data_t data;
+
+  data.free_list = free_list;
+  data.seen = seen;
+  for (i = 0; files[i]; i++)
+    {
+      struct lto_file_decl_data *file = files[i];
+      struct lto_in_decl_state *state = file->global_decl_state;
+      lto_fixup_state (state, &data);
+
+      htab_traverse (file->function_decl_states, lto_fixup_state_aux, &data);
+    }
+
+  for (i = 0; VEC_iterate (tree, lto_global_var_decls, i, decl); i++)
+    {
+      tree saved_decl = decl;
+      walk_tree (&decl, lto_fixup_tree, &data, NULL);
+      if (decl != saved_decl)
+	VEC_replace (tree, lto_global_var_decls, i, decl);
+    }
+
+  pointer_set_traverse (free_list, free_decl, NULL);
+  pointer_set_destroy (free_list);
+  pointer_set_destroy (seen);
+}
+
+/* Unlink a temporary LTRANS file unless requested otherwise.  */
+
+static void
+lto_maybe_unlink (const char *file)
+{
+  if (!getenv ("WPA_SAVE_LTRANS"))
+    {
+      if (unlink_if_ordinary (file))
+        error ("deleting LTRANS input file %s: %m", file);
+    }
+  else
+    fprintf (stderr, "[Leaving LTRANS input file %s]\n", file);
+}
+
+/* Read the options saved from each file in the command line.  Called
+   from lang_hooks.post_options which is called by process_options
+   right before all the options are used to initialize the compiler.
+   This assumes that decode_options has already run, so the
+   num_in_fnames and in_fnames are properly set.
+
+   Note that this assumes that all the files had been compiled with
+   the same options, which is not a good assumption.  In general,
+   options ought to be read from all the files in the set and merged.
+   However, it is still unclear what the merge rules should be.  */
+
+void
+lto_read_all_file_options (void)
+{
+  size_t i;
+
+  /* Clear any file options currently saved.  */
+  lto_clear_file_options ();
+
+  /* Set the hooks to read ELF sections.  */
+  lto_set_in_hooks (NULL, get_section_data, free_section_data);
+
+  for (i = 0; i < num_in_fnames; i++)
+    {
+      struct lto_file_decl_data *file_data;
+      lto_file *file = lto_elf_file_open (in_fnames[i], false);
+      if (!file)
+	break;
+
+      file_data = XCNEW (struct lto_file_decl_data);
+      file_data->file_name = file->filename;
+      file_data->fd = -1;
+      file_data->section_hash_table = lto_elf_build_section_table (file);
+
+      lto_read_file_options (file_data);
+
+      lto_elf_file_close (file);
+      htab_delete (file_data->section_hash_table);
+      if (file_data->fd != -1)
+	close (file_data->fd);
+      free (file_data);
+    }
+
+  /* Apply globally the options read from all the files.  */
+  lto_reissue_options ();
+}
+
+
+/* Read all the symbols from the input files FNAMES.  NFILES is the
+   number of files requested in the command line.  Instantiate a
+   global call graph by aggregating all the sub-graphs found in each
+   file.  */
+
+static void
+read_cgraph_and_symbols (unsigned nfiles, const char **fnames)
+{
+  unsigned int i, last_file_ix;
+  struct lto_file_decl_data **all_file_decl_data;
+  FILE *resolution;
+
+  lto_stats.num_input_files = nfiles;
+
+  timevar_push (TV_IPA_LTO_DECL_IO);
+
+  /* Set the hooks so that all of the ipa passes can read in their data.  */
+  all_file_decl_data = XNEWVEC (struct lto_file_decl_data *, nfiles + 1);
+  lto_set_in_hooks (all_file_decl_data, get_section_data, free_section_data);
+
+  /* Read the resolution file.  */
+  resolution = NULL;
+  if (resolution_file_name)
+    {
+      int t;
+      unsigned num_objects;
+
+      resolution = fopen (resolution_file_name, "r");
+      gcc_assert (resolution != NULL);
+      t = fscanf (resolution, "%u", &num_objects);
+      gcc_assert (t == 1);
+
+      /* True, since the plugin splits the archives.  */
+      gcc_assert (num_objects == nfiles);
+    }
+
+  /* Read all of the object files specified on the command line.  */
+  for (i = 0, last_file_ix = 0; i < nfiles; ++i)
+    {
+      struct lto_file_decl_data *file_data = NULL;
+
+      current_lto_file = lto_elf_file_open (fnames[i], false);
+      if (!current_lto_file)
+	break;
+
+      file_data = lto_file_read (current_lto_file, resolution);
+      if (!file_data)
+	break;
+
+      all_file_decl_data[last_file_ix++] = file_data;
+
+      lto_elf_file_close (current_lto_file);
+      current_lto_file = NULL;
+    }
+
+  if (resolution_file_name)
+    fclose (resolution);
+
+  all_file_decl_data[last_file_ix] = NULL;
+
+  /* Set the hooks so that all of the ipa passes can read in their data.  */
+  lto_set_in_hooks (all_file_decl_data, get_section_data, free_section_data);
+
+  /* Each pass will set the appropriate timer.  */
+  timevar_pop (TV_IPA_LTO_DECL_IO);
+
+  /* Read the callgraph.  */
+  input_cgraph ();
+
+  ipa_read_summaries ();
+
+  timevar_push (TV_IPA_LTO_DECL_IO);
+
+  lto_fixup_decls (all_file_decl_data);
+
+  /* See if we have multiple decls for a symbol and choose the largest
+     one to generate the common.  */
+  for (i = 0; i < VEC_length (tree, lto_global_var_decls); ++i)
+    {
+      tree decl = VEC_index (tree, lto_global_var_decls, i);
+      tree prev_decl = NULL_TREE;
+      tree size;
+
+      if (TREE_CODE (decl) != VAR_DECL
+	  || !DECL_LANG_SPECIFIC (decl))
+	continue;
+
+      /* Find the preceeding decl of the largest one.  */
+      size = DECL_SIZE (decl);
+      do
+	{
+	  tree next = (tree) DECL_LANG_SPECIFIC (decl);
+	  if (tree_int_cst_lt (size, DECL_SIZE (next)))
+	    {
+	      size = DECL_SIZE (next);
+	      prev_decl = decl;
+	    }
+	  decl = next;
+	}
+      while (DECL_LANG_SPECIFIC (decl));
+
+      /* If necessary move the largest decl to the front of the
+	 chain.  */
+      if (prev_decl != NULL_TREE)
+	{
+	  decl = (tree) DECL_LANG_SPECIFIC (prev_decl);
+	  DECL_LANG_SPECIFIC (prev_decl) = DECL_LANG_SPECIFIC (decl);
+	  DECL_LANG_SPECIFIC (decl)
+	    = (struct lang_decl *) VEC_index (tree, lto_global_var_decls, i);
+	  VEC_replace (tree, lto_global_var_decls, i, decl);
+	}
+
+      /* Mark everything apart from the first var as written out and
+         unlink the chain.  */
+      decl = VEC_index (tree, lto_global_var_decls, i);
+      while (DECL_LANG_SPECIFIC (decl))
+	{
+	  tree next = (tree) DECL_LANG_SPECIFIC (decl);
+	  DECL_LANG_SPECIFIC (decl) = NULL;
+	  decl = next;
+	  TREE_ASM_WRITTEN (decl) = true;
+	}
+    }
+
+  /* FIXME lto. This loop needs to be changed to use the pass manager to
+     call the ipa passes directly.  */
+  if (!errorcount)
+    for (i = 0; i < last_file_ix; i++)
+      {
+	struct lto_file_decl_data *file_data = all_file_decl_data [i];
+	lto_materialize_constructors_and_inits (file_data);
+      }
+
+  /* Indicate that the cgraph is built and ready.  */
+  cgraph_function_flags_ready = true;
+
+  timevar_pop (TV_IPA_LTO_DECL_IO);
+}
+
+
+/* Materialize all the bodies for all the nodes in the callgraph.  */
+
+static void
+materialize_cgraph (void)
+{
+  tree decl;
+  struct cgraph_node *node; 
+  unsigned i;
+  timevar_id_t lto_timer;
+
+  /* Now that we have input the cgraph, we need to clear all of the aux
+     nodes and read the functions if we are not running in WPA mode.  */
+  timevar_push (TV_IPA_LTO_GIMPLE_IO);
+
+  for (node = cgraph_nodes; node; node = node->next)
+    {
+      /* Some cgraph nodes get created on the fly, and they don't need
+	 to be materialized.  For instance, nodes for nested functions
+	 where the parent function was not streamed out or builtin
+	 functions.  Additionally, builtin functions should not be
+	 materialized and may, in fact, cause confusion because there
+	 may be a regular function in the file whose assembler name
+	 matches that of the function.
+	 See gcc.c-torture/execute/20030125-1.c and
+	 gcc.c-torture/execute/921215-1.c.  */
+      if (node->local.lto_file_data
+          && !DECL_IS_BUILTIN (node->decl))
+	{
+	  lto_materialize_function (node);
+	  lto_stats.num_input_cgraph_nodes++;
+	}
+    }
+
+  timevar_pop (TV_IPA_LTO_GIMPLE_IO);
+
+  /* Start the appropriate timer depending on the mode that we are
+     operating in.  */
+  lto_timer = (flag_wpa) ? TV_WHOPR_WPA
+	      : (flag_ltrans) ? TV_WHOPR_LTRANS
+	      : TV_LTO;
+  timevar_push (lto_timer);
+
+  current_function_decl = NULL;
+  set_cfun (NULL);
+
+  /* Inform the middle end about the global variables we have seen.  */
+  for (i = 0; VEC_iterate (tree, lto_global_var_decls, i, decl); i++)
+    rest_of_decl_compilation (decl, 1, 0);
+
+  /* Fix up any calls to DECLs that have become not exception throwing.  */
+  lto_fixup_nothrow_decls ();
+
+  timevar_pop (lto_timer);
+}
+
+
+/* Perform whole program analysis (WPA) on the callgraph and write out the
+   optimization plan.  */
+
+static void
+do_whole_program_analysis (void)
+{
+  char **output_files;
+  size_t i;
+  struct cgraph_node *node; 
+
+  lto_1_to_1_map ();
+
+  /* Note that since we are in WPA mode, materialize_cgraph will not
+     actually read in all the function bodies.  It only materializes
+     the decls and cgraph nodes so that analysis can be performed.  */
+  materialize_cgraph ();
+
+  /* Reading in the cgraph uses different timers, start timing WPA now.  */
+  timevar_push (TV_WHOPR_WPA);
+
+  /* FIXME lto. Hack. We should use the IPA passes.  There are a
+     number of issues with this now. 1. There is no convenient way to
+     do this. 2. Some passes may depend on properties that requires
+     the function bodies to compute.  */
+  cgraph_function_flags_ready = true;
+  bitmap_obstack_initialize (NULL);
+  ipa_register_cgraph_hooks ();
+
+  /* Reset inlining information before running IPA inliner.  */
+  for (node = cgraph_nodes; node; node = node->next)
+    reset_inline_failed (node);
+
+  /* FIXME lto.  We should not call this function directly. */
+  pass_ipa_inline.pass.execute ();
+
+  verify_cgraph ();
+  bitmap_obstack_release (NULL);
+
+  /* We are about to launch the final LTRANS phase, stop the WPA timer.  */
+  timevar_pop (TV_WHOPR_WPA);
+
+  output_files = lto_wpa_write_files ();
+
+  /* Show the LTO report before launching LTRANS.  */
+  if (flag_lto_report)
+    print_lto_report ();
+
+  lto_execute_ltrans (output_files);
+
+  for (i = 0; output_files[i]; ++i)
+    {
+      if (output_files[i][0] != '*')
+	lto_maybe_unlink (output_files[i]);
+
+      free (output_files[i]);
+    }
+
+  XDELETEVEC (output_files);
+}
+
+
+/* Main entry point for the GIMPLE front end.  This front end has
+   three main personalities:
+
+   - LTO (-flto).  All the object files on the command line are
+     loaded in memory and processed as a single translation unit.
+     This is the traditional link-time optimization behavior.
+
+   - WPA (-fwpa).  Only the callgraph and summary information for
+     files in the command file are loaded.  A single callgraph
+     (without function bodies) is instantiated for the whole set of
+     files.  IPA passes are only allowed to analyze the call graph
+     and make transformation decisions.  The callgraph is
+     partitioned, each partition is written to a new object file
+     together with the transformation decisions.
+
+   - LTRANS (-fltrans).  Similar to -flto but it prevents the IPA
+     summary files from running again.  Since WPA computed summary
+     information and decided what transformations to apply, LTRANS
+     simply applies them.  */
+
+void
+lto_main (int debug_p ATTRIBUTE_UNUSED)
+{
+  lto_init_reader ();
+
+  /* Read all the symbols and call graph from all the files in the
+     command line.  */
+  read_cgraph_and_symbols (num_in_fnames, in_fnames);
+
+  if (!errorcount)
+    {
+      /* If WPA is enabled analyze the whole call graph and create an
+	 optimization plan.  Otherwise, read in all the function
+	 bodies and continue with optimization.  */
+      if (flag_wpa)
+	do_whole_program_analysis ();
+      else
+	{
+	  materialize_cgraph ();
+
+	  /* Let the middle end know that we have read and merged all of
+	     the input files.  */ 
+	  cgraph_optimize ();
+
+	  /* FIXME lto, if the processes spawned by WPA fail, we miss
+	     the chance to print WPA's report, so WPA will call
+	     print_lto_report before launching LTRANS.  If LTRANS was
+	     launched directly by the driver we would not need to do
+	     this.  */
+	  if (flag_lto_report)
+	    print_lto_report ();
+	}
+    }
+}
+
+#include "gt-lto-lto.h"