PATCH: Define `.gnu_bp_high_bound' symbols from ld.

[Greg McGary <greg at mcgary dot org>]

If there's no good way to define .gnu_bp_high_bound symbols associated
with initialized data, then this is all we'll do in ld: define
high-bound symbols associated with commons.

If there turns out to be a way to handle data, then this patch
is subject to change.  However, for now, I'd like to get this in.

Thanks,
Greg

2000-09-06  Greg McGary  <greg@mcgary.org>

	* ldlang.c (undefined_high_bound_syms_p, high_bound_suffix):
	New variables.
	(lang_find_undefined_high_bound_syms): New function.
	(lang_common): Scan for undefined `.gnu_bp_high_bound' symbols.
	(lang_one_common): Convert the `.gnu_bp_high_bound' symbol
	associated with this common symbol to defined.

Index: ldlang.c
===================================================================
RCS file: /cvs/src/src/ld/ldlang.c,v
retrieving revision 1.30
diff -u -p -r1.30 ldlang.c
--- ldlang.c	2000/09/05 03:21:16	1.30
+++ ldlang.c	2000/09/07 00:30:16
@@ -54,6 +54,8 @@ static struct obstack stat_obstack;
 static const char *startup_file;
 static lang_statement_list_type input_file_chain;
 static boolean placed_commons = false;
+static boolean undefined_high_bound_syms_p = false;
+static char high_bound_suffix[] = ".gnu_bp_high_bound";
 static lang_output_section_statement_type *default_common_section;
 static boolean map_option_f;
 static bfd_vma print_dot;
@@ -133,6 +135,8 @@ static void ignore_bfd_errors PARAMS ((c
 static void lang_check PARAMS ((void));
 static void lang_common PARAMS ((void));
 static boolean lang_one_common PARAMS ((struct bfd_link_hash_entry *, PTR));
+static boolean lang_find_undefined_high_bound_syms
+  PARAMS ((struct bfd_link_hash_entry *, PTR));
 static void lang_place_orphans PARAMS ((void));
 static int topower PARAMS ((int));
 static void lang_set_startof PARAMS ((void));
@@ -3501,6 +3505,10 @@ lang_common ()
       && ! command_line.force_common_definition)
     return;
 
+  /* Determine if there are undefined high-bound symbols.  We want to know
+     this so that we can avoid unnecessary work in lang_one_common.  */
+  bfd_link_hash_traverse (link_info.hash, lang_find_undefined_high_bound_syms, (PTR) NULL);
+
   if (! config.sort_common)
     bfd_link_hash_traverse (link_info.hash, lang_one_common, (PTR) NULL);
   else
@@ -3551,6 +3559,24 @@ lang_one_common (h, info)
   h->u.def.section = section;
   h->u.def.value = section->_cooked_size;
 
+  if (undefined_high_bound_syms_p)
+    {
+      /* Find an associated undefined high-bound symbol, and mark it
+	 as defined with a value equal to the address of the datum
+	 plus that datum's size.  */
+      char *high_bound_name = xmalloc (sizeof (high_bound_suffix) + strlen (h->root.string));
+      struct bfd_link_hash_entry *hbh;
+      sprintf (high_bound_name, "%s%s", h->root.string, high_bound_suffix);
+      hbh = bfd_link_hash_lookup (link_info.hash, high_bound_name, false, false, true);
+      if (hbh)
+	{
+	  hbh->type = bfd_link_hash_defined;
+	  hbh->u.def.section = h->u.def.section;
+	  hbh->u.def.value = h->u.def.value + size;
+	}
+      free (high_bound_name);
+    }
+
   /* Increase the size of the section.  */
   section->_cooked_size += size;
 
@@ -3606,6 +3632,20 @@ lang_one_common (h, info)
       minfo ("%B\n", section->owner);
     }
 
+  return true;
+}
+
+static boolean
+lang_find_undefined_high_bound_syms (h, info)
+     struct bfd_link_hash_entry *h;
+     PTR info ATTRIBUTE_UNUSED;
+{
+  if (h->type == bfd_link_hash_undefined
+      && strstr (h->root.string, high_bound_suffix))
+    {
+      undefined_high_bound_syms_p = true;
+      return false;
+    }
   return true;
 }