[RFC/RFA] Per-objfile data mechanism

[Mark Kettenis <kettenis at chello dot nl>]

This patch adds a per-objfile data mechanism to GDB, and uses that to
store DWARF2 frame info instead of abusing objfile->sym_private.  The
latter could lead to problems on certain platforms according to
Daniel.

Comments?  OK to check this in?  Do we want this on the release branch
too?

Mark


Index: ChangeLog
from  Mark Kettenis  <kettenis@gnu.org>
 
	* objfiles.h (struct objfile): Add memebers `data' and `num_data'.
	(register_objfile_data, set_objfile_data, objfile_data): New
	prototypes.
	* objfiles.c (objfile_alloc_data, objfile_free_data): New
	prototypes.
	(allocate_objfile): Call objfile_alloc_data.
	(free_objfile): Call objfile_free_data.
	(struct objfile_data): New.
	(struct objfile_data_registration): New.
	(struct objfile_data_registry): New.
	(objfile_data_registry): New variable.
	(register_objfile_data): New function.
	(objfile_alloc_data, objfile_free_data): New functions.
	(set_objfile_data, objfile_data): New functions.
	* dwarf2-frame.c (dwarf2_frame_data): New variable.
	(dwarf2_frame_find_fde, add_fde): Use new per-objfile data mechanism.
	(_initialize_dwarf2_frame): New function and prototype.

 
Index: objfiles.h
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.h,v
retrieving revision 1.22
diff -u -p -r1.22 objfiles.h
--- objfiles.h 24 Mar 2003 03:54:48 -0000 1.22
+++ objfiles.h 13 Jul 2003 17:16:04 -0000
@@ -379,6 +379,13 @@ struct objfile
 
     void *obj_private;
 
+    /* Per objfile data-pointers required by other GDB modules.  */
+    /* FIXME: kettenis/20030711: This mechanism could replace
+       sym_stab_info, sym_private and obj_private entirely.  */
+
+    void **data;
+    unsigned num_data;
+
     /* Set of relocation offsets to apply to each section.
        Currently on the psymbol_obstack (which makes no sense, but I'm
        not sure it's harming anything).
@@ -564,6 +571,16 @@ extern struct obj_section *find_pc_sect_
 extern int in_plt_section (CORE_ADDR, char *);
 
 extern int is_in_import_list (char *, struct objfile *);
+
+/* Keep a registry of per-objfile data-pointers required by other GDB
+   modules.  */
+
+extern const struct objfile_data *register_objfile_data (void);
+extern void set_objfile_data (struct objfile *objfile,
+			      const struct objfile_data *data, void *value);
+extern void *objfile_data (struct objfile *objfile,
+			   const struct objfile_data *data);
+
 
 /* Traverse all object files.  ALL_OBJFILES_SAFE works even if you delete
    the objfile during the traversal.  */
Index: objfiles.c
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.c,v
retrieving revision 1.33
diff -u -p -r1.33 objfiles.c
--- objfiles.c 11 Jun 2003 23:29:47 -0000 1.33
+++ objfiles.c 13 Jul 2003 17:16:05 -0000
@@ -34,6 +34,7 @@
 #include "target.h"
 #include "bcache.h"
 
+#include "gdb_assert.h"
 #include <sys/types.h>
 #include "gdb_stat.h"
 #include <fcntl.h>
@@ -61,6 +62,9 @@ static void *map_to_file (int);
 
 static void add_to_objfile_sections (bfd *, sec_ptr, void *);
 
+static void objfile_alloc_data (struct objfile *objfile);
+static void objfile_free_data (struct objfile *objfile);
+
 /* Externally visible variables that are owned by this module.
    See declarations in objfile.h for more info. */
 
@@ -302,6 +306,8 @@ allocate_objfile (bfd *abfd, int flags)
       terminate_minimal_symbol_table (objfile);
     }
 
+  objfile_alloc_data (objfile);
+
   /* Update the per-objfile information that comes from the bfd, ensuring
      that any data that is reference is saved in the per-objfile data
      region. */
@@ -561,6 +567,7 @@ free_objfile (struct objfile *objfile)
 
   if (objfile != NULL)
     {
+      objfile_free_data (objfile);
       if (objfile->name != NULL)
 	{
 	  xmfree (objfile->md, objfile->name);
@@ -1097,4 +1104,74 @@ is_in_import_list (char *name, struct ob
       return 1;
   return 0;
 }
+
+
+/* Keep a registry of per-objfile data-pointers required by other GDB
+   modules.  */
+
+struct objfile_data
+{
+  unsigned index;
+};
+
+struct objfile_data_registration
+{
+  struct objfile_data *data;
+  struct objfile_data_registration *next;
+};
+  
+struct objfile_data_registry
+{
+  struct objfile_data_registration *registrations;
+  unsigned num_registrations;
+};
+
+static struct objfile_data_registry objfile_data_registry = { NULL, 0 };
+
+const struct objfile_data *
+register_objfile_data (void)
+{
+  struct objfile_data_registration **curr;
+
+  /* Append new registration.  */
+  for (curr = &objfile_data_registry.registrations;
+       *curr != NULL; curr = &(*curr)->next);
 
+  *curr = XMALLOC (struct objfile_data_registration);
+  (*curr)->next = NULL;
+  (*curr)->data = XMALLOC (struct objfile_data);
+  (*curr)->data->index = objfile_data_registry.num_registrations++;
+
+  return (*curr)->data;
+}
+
+static void
+objfile_alloc_data (struct objfile *objfile)
+{
+  gdb_assert (objfile->data == NULL);
+  objfile->num_data = objfile_data_registry.num_registrations;
+  objfile->data = XCALLOC (objfile->num_data, void *);
+}
+
+static void
+objfile_free_data (struct objfile *objfile)
+{
+  gdb_assert (objfile->data != NULL);
+  xfree (objfile->data);
+  objfile->data = NULL;
+}
+
+void
+set_objfile_data (struct objfile *objfile, const struct objfile_data *data,
+		  void *value)
+{
+  gdb_assert (data->index < objfile->num_data);
+  objfile->data[data->index] = value;
+}
+
+void *
+objfile_data (struct objfile *objfile, const struct objfile_data *data)
+{
+  gdb_assert (data->index < objfile->num_data);
+  return objfile->data[data->index];
+}
Index: dwarf2-frame.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.c,v
retrieving revision 1.8
diff -u -p -r1.8 dwarf2-frame.c
--- dwarf2-frame.c 11 Jul 2003 16:22:17 -0000 1.8
+++ dwarf2-frame.c 13 Jul 2003 17:16:21 -0000
@@ -785,6 +785,8 @@ struct comp_unit
   bfd_vma dbase;
 };
 
+const struct objfile_data *dwarf2_frame_data;
+
 static unsigned int
 read_1_byte (bfd *bfd, char *buf)
 {
@@ -1029,7 +1031,7 @@ dwarf2_frame_find_fde (CORE_ADDR *pc)
 
       offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
       
-      fde = objfile->sym_private;
+      fde = objfile_data (objfile, dwarf2_frame_data);
       while (fde)
 	{
 	  if (*pc >= fde->initial_location + offset
@@ -1049,8 +1051,8 @@ dwarf2_frame_find_fde (CORE_ADDR *pc)
 static void
 add_fde (struct comp_unit *unit, struct dwarf2_fde *fde)
 {
-  fde->next = unit->objfile->sym_private;
-  unit->objfile->sym_private = fde;
+  fde->next = objfile_data (unit->objfile, dwarf2_frame_data);
+  set_objfile_data (unit->objfile, dwarf2_frame_data, fde);
 }
 
 #ifdef CC_HAS_LONG_LONG
@@ -1445,4 +1447,13 @@ dwarf2_build_frame_info (struct objfile 
       while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size)
 	frame_ptr = decode_frame_entry (&unit, frame_ptr, 0);
     }
+}
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+void _initialize_dwarf2_frame (void);
+
+void
+_initialize_dwarf2_frame (void)
+{
+  dwarf2_frame_data = register_objfile_data ();
 }