diff --git a/gcc/coverage.c b/gcc/coverage.c
index 10d7f8366cb..4467f1eaa5c 100644
--- a/gcc/coverage.c
+++ b/gcc/coverage.c
@@ -129,16 +129,7 @@ static const char *const ctr_names[GCOV_COUNTERS] = {
  #undef DEF_GCOV_COUNTER
  
  /* Forward declarations.  */
-static void read_counts_file (void);
  static tree build_var (tree, tree, int);
-static void build_fn_info_type (tree, unsigned, tree);
-static void build_info_type (tree, tree);
-static tree build_fn_info (const struct coverage_data *, tree, tree);
-static tree build_info (tree, tree);
-static bool coverage_obj_init (void);
-static vec<constructor_elt, va_gc> *coverage_obj_fn
-(vec<constructor_elt, va_gc> *, tree, struct coverage_data const *);
-static void coverage_obj_finish (vec<constructor_elt, va_gc> *);
  
  /* Return the type node for gcov_type.  */
  
@@ -218,6 +209,9 @@ read_counts_file (void)
    tag = gcov_read_unsigned ();
    bbg_file_stamp = crc32_unsigned (bbg_file_stamp, tag);
  
+  /* Read checksum.  */
+  gcov_read_unsigned ();
+
    counts_hash = new hash_table<counts_entry> (10);
    while ((tag = gcov_read_unsigned ()))
      {
@@ -935,6 +929,12 @@ build_info_type (tree type, tree fn_info_ptr_type)
    DECL_CHAIN (field) = fields;
    fields = field;
  
+  /* Checksum.  */
+  field = build_decl (BUILTINS_LOCATION, FIELD_DECL, NULL_TREE,
+		      get_gcov_unsigned_t ());
+  DECL_CHAIN (field) = fields;
+  fields = field;
+
    /* Filename */
    field = build_decl (BUILTINS_LOCATION, FIELD_DECL, NULL_TREE,
  		      build_pointer_type (build_qualified_type
@@ -977,7 +977,7 @@ build_info_type (tree type, tree fn_info_ptr_type)
     function info objects.  */
  
  static tree
-build_info (tree info_type, tree fn_ary)
+build_info (tree info_type, tree fn_ary, unsigned object_checksum)
  {
    tree info_fields = TYPE_FIELDS (info_type);
    tree merge_fn_type, n_funcs;
@@ -996,13 +996,19 @@ build_info (tree info_type, tree fn_ary)
    /* next -- NULL */
    CONSTRUCTOR_APPEND_ELT (v1, info_fields, null_pointer_node);
    info_fields = DECL_CHAIN (info_fields);
-
+
    /* stamp */
    CONSTRUCTOR_APPEND_ELT (v1, info_fields,
  			  build_int_cstu (TREE_TYPE (info_fields),
  					  bbg_file_stamp));
    info_fields = DECL_CHAIN (info_fields);
  
+  /* Checksum.  */
+  CONSTRUCTOR_APPEND_ELT (v1, info_fields,
+			  build_int_cstu (TREE_TYPE (info_fields),
+					  object_checksum));
+  info_fields = DECL_CHAIN (info_fields);
+
    /* Filename */
    da_file_name_len = strlen (da_file_name);
    filename_string = build_string (da_file_name_len + 1, da_file_name);
@@ -1214,7 +1220,8 @@ coverage_obj_fn (vec<constructor_elt, va_gc> *ctor, tree fn,
     function objects from CTOR.  Generate the gcov_info initializer.  */
  
  static void
-coverage_obj_finish (vec<constructor_elt, va_gc> *ctor)
+coverage_obj_finish (vec<constructor_elt, va_gc> *ctor,
+		     unsigned object_checksum)
  {
    unsigned n_functions = vec_safe_length (ctor);
    tree fn_info_ary_type = build_array_type
@@ -1231,7 +1238,7 @@ coverage_obj_finish (vec<constructor_elt, va_gc> *ctor)
    varpool_node::finalize_decl (fn_info_ary);
    
    DECL_INITIAL (gcov_info_var)
-    = build_info (TREE_TYPE (gcov_info_var), fn_info_ary);
+    = build_info (TREE_TYPE (gcov_info_var), fn_info_ary, object_checksum);
    varpool_node::finalize_decl (gcov_info_var);
  }
  
@@ -1300,7 +1307,6 @@ coverage_init (const char *filename)
    strcpy (da_file_name + prefix_len + len, GCOV_DATA_SUFFIX);
  
    bbg_file_stamp = local_tick;
-
    if (flag_auto_profile)
      read_autofdo_file ();
    else if (flag_branch_probabilities)
@@ -1328,6 +1334,8 @@ coverage_init (const char *filename)
  	  gcov_write_unsigned (GCOV_NOTE_MAGIC);
  	  gcov_write_unsigned (GCOV_VERSION);
  	  gcov_write_unsigned (bbg_file_stamp);
+	  /* Use an arbitrary checksum */
+	  gcov_write_unsigned (0);
  	  gcov_write_string (getpwd ());
  
  	  /* Do not support has_unexecuted_blocks for Ada.  */
@@ -1353,14 +1361,24 @@ coverage_finish (void)
         cannot uniquely stamp it.  If we can stamp it, libgcov will DTRT.  */
      unlink (da_file_name);
  
+  /* Global GCDA checksum that aggregates all functions.  */
+  unsigned object_checksum = 0;
+
    if (coverage_obj_init ())
      {
        vec<constructor_elt, va_gc> *fn_ctor = NULL;
        struct coverage_data *fn;
        
        for (fn = functions_head; fn; fn = fn->next)
-	fn_ctor = coverage_obj_fn (fn_ctor, fn->fn_decl, fn);
-      coverage_obj_finish (fn_ctor);
+	{
+	  fn_ctor = coverage_obj_fn (fn_ctor, fn->fn_decl, fn);
+
+	  object_checksum = crc32_unsigned (object_checksum, fn->ident);
+	  object_checksum = crc32_unsigned (object_checksum,
+					    fn->lineno_checksum);
+	  object_checksum = crc32_unsigned (object_checksum, fn->cfg_checksum);
+	}
+      coverage_obj_finish (fn_ctor, object_checksum);
      }
  
    XDELETEVEC (da_file_name);
diff --git a/gcc/gcov-dump.c b/gcc/gcov-dump.c
index f1489fe0214..bfaf735d2ff 100644
--- a/gcc/gcov-dump.c
+++ b/gcc/gcov-dump.c
@@ -206,11 +206,12 @@ dump_gcov_file (const char *filename)
    }
  
    /* stamp */
-  {
-    unsigned stamp = gcov_read_unsigned ();
+  unsigned stamp = gcov_read_unsigned ();
+  printf ("%s:stamp %lu\n", filename, (unsigned long)stamp);
  
-    printf ("%s:stamp %lu\n", filename, (unsigned long)stamp);
-  }
+  /* Checksum */
+  unsigned checksum = gcov_read_unsigned ();
+  printf ("%s:checksum %lu\n", filename, (unsigned long)checksum);
  
    if (!is_data_type)
      {
diff --git a/gcc/gcov.c b/gcc/gcov.c
index cf0a49d8c30..829e955a63b 100644
--- a/gcc/gcov.c
+++ b/gcc/gcov.c
@@ -1814,6 +1814,8 @@ read_graph_file (void)
  	       bbg_file_name, v, e);
      }
    bbg_stamp = gcov_read_unsigned ();
+  /* Read checksum.  */
+  gcov_read_unsigned ();
    bbg_cwd = xstrdup (gcov_read_string ());
    bbg_supports_has_unexecuted_blocks = gcov_read_unsigned ();
  
@@ -2031,6 +2033,9 @@ read_count_file (void)
        goto cleanup;
      }
  
+  /* Read checksum.  */
+  gcov_read_unsigned ();
+
    while ((tag = gcov_read_unsigned ()))
      {
        unsigned length = gcov_read_unsigned ();
diff --git a/libgcc/libgcov-driver.c b/libgcc/libgcov-driver.c
index 087f71e0107..7aa97bbb06a 100644
--- a/libgcc/libgcov-driver.c
+++ b/libgcc/libgcov-driver.c
@@ -260,12 +260,15 @@ merge_one_data (const char *filename,
    if (!gcov_version (gi_ptr, length, filename))
      return -1;
  
+  /* Skip timestamp.  */
+  gcov_read_unsigned ();
+
    length = gcov_read_unsigned ();
-  if (length != gi_ptr->stamp)
+  if (length != gi_ptr->checksum)
      {
        /* Read from a different compilation.  Overwrite the file.  */
        gcov_error (GCOV_PROF_PREFIX "overwriting an existing profile data "
-		  "with a different timestamp\n", filename);
+		  "with a different checksum\n", filename);
        return 0;
      }
  
@@ -495,6 +498,7 @@ write_one_data (const struct gcov_info *gi_ptr,
    dump_unsigned (GCOV_DATA_MAGIC, dump_fn, arg);
    dump_unsigned (GCOV_VERSION, dump_fn, arg);
    dump_unsigned (gi_ptr->stamp, dump_fn, arg);
+  dump_unsigned (gi_ptr->checksum, dump_fn, arg);
  
  #ifdef NEED_L_GCOV
    /* Generate whole program statistics.  */
diff --git a/libgcc/libgcov-util.c b/libgcc/libgcov-util.c
index bc7416d99bf..766ca3559c4 100644
--- a/libgcc/libgcov-util.c
+++ b/libgcc/libgcov-util.c
@@ -310,6 +310,9 @@ read_gcda_file (const char *filename)
    /* Read stamp.  */
    obj_info->stamp = gcov_read_unsigned ();
  
+  /* Read checksum.  */
+  obj_info->checksum = gcov_read_unsigned ();
+
    while (1)
      {
        gcov_position_t base;
diff --git a/libgcc/libgcov.h b/libgcc/libgcov.h
index f6354a7a070..2a365c95759 100644
--- a/libgcc/libgcov.h
+++ b/libgcc/libgcov.h
@@ -230,6 +230,7 @@ struct gcov_info
    struct gcov_info *next;	/* link to next, used by libgcov */
  
    gcov_unsigned_t stamp;	/* uniquifying time stamp */
+  gcov_unsigned_t checksum;	/* unique object checksum */
    const char *filename;		/* output file name */
  
    gcov_merge_fn merge[GCOV_COUNTERS];  /* merge functions (null for
