[RFA 2/3] New "iterate_over_objfiles_in_search_order" gdbarch method.

[RFA 2/3] New "iterate_over_objfiles_in_search_order" gdbarch method.

[Joel Brobecker]

This patch introduces the "iterate_over_objfiles_in_search_order"
gdbarch method, as well as its default implementation, and converts
the areas where it will matter to using this gdbarch method.

The default method implementation is the only one installed, and
the changes should have no functional impact in terms of behavior.
This only paves the way for the architectures that will need their
own version.

gdb/ChangeLog:

        * gdbarch.sh: Add include of "objfiles.h" in gdbarch.c.
        (iterate_over_objfiles_in_search_order): New gdbarch method.
        * gdbarch.h, gdbarch.c: Regenerate.
        * objfiles.h (default_iterate_over_objfiles_in_search_order):
        Add declaration.
        * objfiles.c (default_iterate_over_objfiles_in_search_order):
        New function.
        * symtab.c (lookup_symbol_aux_objfile): New function, extracted
        out of lookup_symbol_aux_symtabs.
        (lookup_symbol_aux_symtabs): Replace extracted-out code by
        call to lookup_symbol_aux_objfile.
        (struct global_sym_lookup_data): New type.
        (lookup_symbol_global_iterator_cb): New function.
        (lookup_symbol_global): Search for symbol using
        gdbarch_iterate_over_objfiles_in_search_order and
        lookup_symbol_global_iterator_cb.
        * findvar.c (struct minsym_lookup_data): New type.
        (minsym_lookup_iterator_cb): New function.
        (default_read_var_value) [case LOC_UNRESOLVED]: Resolve the
        symbol's address via gdbarch_iterate_over_objfiles_in_search_order
        and minsym_lookup_iterator_cb.

OK to commit?
Thanks,
-- 
Joel

---
 gdb/findvar.c  |   42 +++++++++++++++++++-
 gdb/gdbarch.c  |   25 ++++++++++++
 gdb/gdbarch.h  |   18 ++++++++
 gdb/gdbarch.sh |   16 ++++++++
 gdb/objfiles.c |   25 ++++++++++++
 gdb/objfiles.h |    5 ++
 gdb/symtab.c   |  118 ++++++++++++++++++++++++++++++++++++++++----------------
 7 files changed, 215 insertions(+), 34 deletions(-)

diff --git a/gdb/findvar.c b/gdb/findvar.c
index 9009e6f..66bcebe 100644
--- a/gdb/findvar.c
+++ b/gdb/findvar.c
@@ -406,6 +406,37 @@ symbol_read_needs_frame (struct symbol *sym)
   return 1;
 }
 
+/* Private data to be used with minsym_lookup_iterator_cb.  */
+
+struct minsym_lookup_data
+{
+  /* The name of the minimal symbol we are searching for.  */
+  const char *name;
+
+  /* The field where the callback should store the minimal symbol
+     if found.  It should be initialized to NULL before the search
+     is started.  */
+  struct minimal_symbol *result;
+};
+
+/* A callback function for gdbarch_iterate_over_objfiles_in_search_order.
+   It searches by name for a minimal symbol within the given OBJFILE.
+   The arguments are passed via CB_DATA, which in reality is a pointer
+   to struct minsym_lookup_data.  */
+
+static int
+minsym_lookup_iterator_cb (struct objfile *objfile, void *cb_data)
+{
+  struct minsym_lookup_data *data = (struct minsym_lookup_data *) cb_data;
+
+  gdb_assert (data->result == NULL);
+
+  data->result = lookup_minimal_symbol (data->name, NULL, objfile);
+
+  /* The iterator should stop iff a match was found.  */
+  return (data->result != NULL);
+}
+
 /* A default implementation for the "la_read_var_value" hook in
    the language vector which should work in most situations.  */
 
@@ -559,10 +590,19 @@ default_read_var_value (struct symbol *var, struct frame_info *frame)
 
     case LOC_UNRESOLVED:
       {
+	struct minsym_lookup_data lookup_data;
 	struct minimal_symbol *msym;
 	struct obj_section *obj_section;
 
-	msym = lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var), NULL, NULL);
+	memset (&lookup_data, 0, sizeof (lookup_data));
+	lookup_data.name = SYMBOL_LINKAGE_NAME (var);
+
+	gdbarch_iterate_over_objfiles_in_search_order
+	  (get_objfile_arch (SYMBOL_SYMTAB (var)->objfile),
+	   minsym_lookup_iterator_cb, &lookup_data,
+	   SYMBOL_SYMTAB (var)->objfile);
+	msym = lookup_data.result;
+
 	if (msym == NULL)
 	  error (_("No global symbol \"%s\"."), SYMBOL_LINKAGE_NAME (var));
 	if (overlay_debugging)
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 3ebe835..5d360af 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -49,6 +49,7 @@
 #include "gdb_obstack.h"
 #include "observer.h"
 #include "regcache.h"
+#include "objfiles.h"
 
 /* Static function declarations */
 
@@ -284,6 +285,7 @@ struct gdbarch
   int has_dos_based_file_system;
   gdbarch_gen_return_address_ftype *gen_return_address;
   gdbarch_info_proc_ftype *info_proc;
+  gdbarch_iterate_over_objfiles_in_search_order_ftype *iterate_over_objfiles_in_search_order;
 };
 
 
@@ -451,6 +453,7 @@ struct gdbarch startup_gdbarch =
   0,  /* has_dos_based_file_system */
   default_gen_return_address,  /* gen_return_address */
   0,  /* info_proc */
+  default_iterate_over_objfiles_in_search_order,  /* iterate_over_objfiles_in_search_order */
   /* startup_gdbarch() */
 };
 
@@ -542,6 +545,7 @@ gdbarch_alloc (const struct gdbarch_info *info,
   gdbarch->auto_charset = default_auto_charset;
   gdbarch->auto_wide_charset = default_auto_wide_charset;
   gdbarch->gen_return_address = default_gen_return_address;
+  gdbarch->iterate_over_objfiles_in_search_order = default_iterate_over_objfiles_in_search_order;
   /* gdbarch_alloc() */
 
   return gdbarch;
@@ -750,6 +754,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of has_dos_based_file_system, invalid_p == 0 */
   /* Skip verify of gen_return_address, invalid_p == 0 */
   /* Skip verify of info_proc, has predicate.  */
+  /* Skip verify of iterate_over_objfiles_in_search_order, invalid_p == 0 */
   buf = ui_file_xstrdup (log, &length);
   make_cleanup (xfree, buf);
   if (length > 0)
@@ -1065,6 +1070,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
                       "gdbarch_dump: integer_to_address = <%s>\n",
                       host_address_to_string (gdbarch->integer_to_address));
   fprintf_unfiltered (file,
+                      "gdbarch_dump: iterate_over_objfiles_in_search_order = <%s>\n",
+                      host_address_to_string (gdbarch->iterate_over_objfiles_in_search_order));
+  fprintf_unfiltered (file,
                       "gdbarch_dump: long_bit = %s\n",
                       plongest (gdbarch->long_bit));
   fprintf_unfiltered (file,
@@ -4236,6 +4244,23 @@ set_gdbarch_info_proc (struct gdbarch *gdbarch,
   gdbarch->info_proc = info_proc;
 }
 
+void
+gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch, int (*cb) (struct objfile *objfile, void *cb_data), void *cb_data, struct objfile *current_objfile)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->iterate_over_objfiles_in_search_order != NULL);
+  if (gdbarch_debug >= 2)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_iterate_over_objfiles_in_search_order called\n");
+  gdbarch->iterate_over_objfiles_in_search_order (gdbarch, cb, cb_data, current_objfile);
+}
+
+void
+set_gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch,
+                                                   gdbarch_iterate_over_objfiles_in_search_order_ftype iterate_over_objfiles_in_search_order)
+{
+  gdbarch->iterate_over_objfiles_in_search_order = iterate_over_objfiles_in_search_order;
+}
+
 
 /* Keep a registry of per-architecture data-pointers required by GDB
    modules.  */
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index 5d73d72..8bbe0f0 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -1171,6 +1171,24 @@ typedef void (gdbarch_info_proc_ftype) (struct gdbarch *gdbarch, char *args, enu
 extern void gdbarch_info_proc (struct gdbarch *gdbarch, char *args, enum info_proc_what what);
 extern void set_gdbarch_info_proc (struct gdbarch *gdbarch, gdbarch_info_proc_ftype *info_proc);
 
+/* Iterate over all objfiles in the order that makes the most sense
+   for the architecture to make global symbol searches.
+  
+   CB is a callback function where OBJFILE is the objfile to be searched,
+   and CB_DATA a pointer to user-defined data (the same data that is passed
+   when calling this gdbarch method).  The iteration stops if this function
+   returns nonzero.
+  
+   CB_DATA is a pointer to some user-defined data to be passed to
+   the callback.
+  
+   If not NULL, CURRENT_OBJFILE corresponds to the objfile being
+   inspected when the symbol search was requested. */
+
+typedef void (gdbarch_iterate_over_objfiles_in_search_order_ftype) (struct gdbarch *gdbarch, int (*cb) (struct objfile *objfile, void *cb_data), void *cb_data, struct objfile *current_objfile);
+extern void gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch, int (*cb) (struct objfile *objfile, void *cb_data), void *cb_data, struct objfile *current_objfile);
+extern void set_gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch, gdbarch_iterate_over_objfiles_in_search_order_ftype *iterate_over_objfiles_in_search_order);
+
 /* Definition for an unknown syscall, used basically in error-cases.  */
 #define UNKNOWN_SYSCALL (-1)
 
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index cc1fe65..167eb2e 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -934,6 +934,21 @@ m:void:gen_return_address:struct agent_expr *ax, struct axs_value *value, CORE_A
 # Implement the "info proc" command.
 M:void:info_proc:char *args, enum info_proc_what what:args, what
 
+# Iterate over all objfiles in the order that makes the most sense
+# for the architecture to make global symbol searches.
+#
+# CB is a callback function where OBJFILE is the objfile to be searched,
+# and CB_DATA a pointer to user-defined data (the same data that is passed
+# when calling this gdbarch method).  The iteration stops if this function
+# returns nonzero.
+#
+# CB_DATA is a pointer to some user-defined data to be passed to
+# the callback.
+#
+# If not NULL, CURRENT_OBJFILE corresponds to the objfile being
+# inspected when the symbol search was requested.
+m:void:iterate_over_objfiles_in_search_order:int (*cb) (struct objfile *objfile, void *cb_data), void *cb_data, struct objfile *current_objfile:cb, cb_data, current_objfile:0:default_iterate_over_objfiles_in_search_order::0
+
 EOF
 }
 
@@ -1380,6 +1395,7 @@ cat <<EOF
 #include "gdb_obstack.h"
 #include "observer.h"
 #include "regcache.h"
+#include "objfiles.h"
 
 /* Static function declarations */
 
diff --git a/gdb/objfiles.c b/gdb/objfiles.c
index 8d9f8a5..daa6068 100644
--- a/gdb/objfiles.c
+++ b/gdb/objfiles.c
@@ -1525,6 +1525,31 @@ gdb_bfd_unref (struct bfd *abfd)
   xfree (name);
 }
 
+/* The default implementation for the "iterate_over_objfiles_in_search_order"
+   gdbarch method.  It is equivalent to use the ALL_OBJFILES macro,
+   searching the objfiles in the order they are stored internally,
+   ignoring CURRENT_OBJFILE.
+
+   On most platorms, it should be close enough to doing the best
+   we can without some knowledge specific to the architecture.  */
+
+void
+default_iterate_over_objfiles_in_search_order
+  (struct gdbarch *gdbarch,
+   int (*cb) (struct objfile *objfile, void *cb_data),
+   void *cb_data, struct objfile *current_objfile)
+{
+  int stop = 0;
+  struct objfile *objfile;
+
+  ALL_OBJFILES (objfile)
+    {
+       stop = cb (objfile, cb_data);
+       if (stop)
+	 return;
+    }
+}
+
 /* Provide a prototype to silence -Wmissing-prototypes.  */
 extern initialize_file_ftype _initialize_objfiles;
 
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index d5c807f..0c4f723 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -525,6 +525,11 @@ extern void *objfile_data (struct objfile *objfile,
 extern struct bfd *gdb_bfd_ref (struct bfd *abfd);
 extern void gdb_bfd_unref (struct bfd *abfd);
 extern int gdb_bfd_close_or_warn (struct bfd *abfd);
+
+extern void default_iterate_over_objfiles_in_search_order
+  (struct gdbarch *gdbarch,
+   int (*cb) (struct objfile *objfile, void *cb_data),
+   void *cb_data, struct objfile *current_objfile);
 \f
 
 /* Traverse all object files in the current program space.
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 39d8c6f..57c55b6 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -1498,40 +1498,55 @@ lookup_global_symbol_from_objfile (const struct objfile *main_objfile,
   return NULL;
 }
 
-/* Check to see if the symbol is defined in one of the symtabs.
-   BLOCK_INDEX should be either GLOBAL_BLOCK or STATIC_BLOCK,
+/* Check to see if the symbol is defined in one of the OBJFILE's
+   symtabs.  BLOCK_INDEX should be either GLOBAL_BLOCK or STATIC_BLOCK,
    depending on whether or not we want to search global symbols or
    static symbols.  */
 
 static struct symbol *
+lookup_symbol_aux_objfile (struct objfile *objfile, int block_index,
+			   const char *name, const domain_enum domain)
+{
+  struct symbol *sym = NULL;
+  struct blockvector *bv;
+  const struct block *block;
+  struct symtab *s;
+
+  if (objfile->sf)
+    objfile->sf->qf->pre_expand_symtabs_matching (objfile, block_index,
+						  name, domain);
+
+  ALL_OBJFILE_SYMTABS (objfile, s)
+    if (s->primary)
+      {
+	bv = BLOCKVECTOR (s);
+	block = BLOCKVECTOR_BLOCK (bv, block_index);
+	sym = lookup_block_symbol (block, name, domain);
+	if (sym)
+	  {
+	    block_found = block;
+	    return fixup_symbol_section (sym, objfile);
+	  }
+      }
+
+  return NULL;
+}
+
+/* Same as lookup_symbol_aux_objfile, except that it searches all
+   objfiles.  Return the first match found.  */
+
+static struct symbol *
 lookup_symbol_aux_symtabs (int block_index, const char *name,
 			   const domain_enum domain)
 {
   struct symbol *sym;
   struct objfile *objfile;
-  struct blockvector *bv;
-  const struct block *block;
-  struct symtab *s;
 
   ALL_OBJFILES (objfile)
   {
-    if (objfile->sf)
-      objfile->sf->qf->pre_expand_symtabs_matching (objfile,
-						    block_index,
-						    name, domain);
-
-    ALL_OBJFILE_SYMTABS (objfile, s)
-      if (s->primary)
-	{
-	  bv = BLOCKVECTOR (s);
-	  block = BLOCKVECTOR_BLOCK (bv, block_index);
-	  sym = lookup_block_symbol (block, name, domain);
-	  if (sym)
-	    {
-	      block_found = block;
-	      return fixup_symbol_section (sym, objfile);
-	    }
-	}
+    sym = lookup_symbol_aux_objfile (objfile, block_index, name, domain);
+    if (sym)
+      return sym;
   }
 
   return NULL;
@@ -1648,6 +1663,46 @@ lookup_symbol_static (const char *name,
     return NULL;
 }
 
+/* Private data to be used with lookup_symbol_global_iterator_cb.  */
+
+struct global_sym_lookup_data
+{
+  /* The name of the symbol we are searching for.  */
+  const char *name;
+
+  /* The domain to use for our search.  */
+  domain_enum domain;
+
+  /* The field where the callback should store the symbol if found.
+     It should be initialized to NULL before the search is started.  */
+  struct symbol *result;
+};
+
+/* A callback function for gdbarch_iterate_over_objfiles_in_search_order.
+   It searches by name for a symbol in the GLOBAL_BLOCK of the given
+   OBJFILE.  The arguments for the search are passed via CB_DATA,
+   which in reality is a pointer to struct global_sym_lookup_data.  */
+
+static int
+lookup_symbol_global_iterator_cb (struct objfile *objfile,
+				  void *cb_data)
+{
+  struct global_sym_lookup_data *data =
+    (struct global_sym_lookup_data *) cb_data;
+
+  gdb_assert (data->result == NULL);
+
+  data->result = lookup_symbol_aux_objfile (objfile, GLOBAL_BLOCK,
+					    data->name, data->domain);
+  if (data->result == NULL)
+    data->result = lookup_symbol_aux_quick (objfile, GLOBAL_BLOCK,
+					    data->name, data->domain);
+
+  /* If we found a match, tell the iterator to stop.  Otherwise,
+     keep going.  */
+  return (data->result != NULL);
+}
+
 /* Lookup a symbol in all files' global blocks (searching psymtabs if
    necessary).  */
 
@@ -1658,6 +1713,7 @@ lookup_symbol_global (const char *name,
 {
   struct symbol *sym = NULL;
   struct objfile *objfile = NULL;
+  struct global_sym_lookup_data lookup_data;
 
   /* Call library-specific lookup procedure.  */
   objfile = lookup_objfile_from_block (block);
@@ -1666,18 +1722,14 @@ lookup_symbol_global (const char *name,
   if (sym != NULL)
     return sym;
 
-  sym = lookup_symbol_aux_symtabs (GLOBAL_BLOCK, name, domain);
-  if (sym != NULL)
-    return sym;
-
-  ALL_OBJFILES (objfile)
-  {
-    sym = lookup_symbol_aux_quick (objfile, GLOBAL_BLOCK, name, domain);
-    if (sym)
-      return sym;
-  }
+  memset (&lookup_data, 0, sizeof (lookup_data));
+  lookup_data.name = name;
+  lookup_data.domain = domain;
+  gdbarch_iterate_over_objfiles_in_search_order
+    (objfile != NULL ? get_objfile_arch (objfile) : target_gdbarch,
+     lookup_symbol_global_iterator_cb, &lookup_data, objfile);
 
-  return NULL;
+  return lookup_data.result;
 }
 
 int
-- 
1.7.1

[RFA 3/3] Windows-specific iterate_over_objfiles_in_search_order

[Joel Brobecker]

This patch sets the windows target to use their own version of
the iterate_over_objfiles_in_search_order gdbarch method, in
order to make global symbol searches sensitive to the current
objfile.

gdb/ChangeLog:

        * windows-tdep.h (windows_iterate_over_objfiles_in_search_order):
        Add declaration.
        * windows-tdep.c: #include "objfiles.h".
        (windows_iterate_over_objfiles_in_search_order): New function.
        * amd64-windows-tdep.c (amd64_windows_init_abi): Set
        iterate_over_objfiles_in_search_order gdbarch method to
        windows_iterate_over_objfiles_in_search_order.
        * i386-cygwin-tdep.c (i386_cygwin_init_abi): Likewise.

I'll commit after patch #2 is approved, unless there are objections...

Thanks,
-- 
Joel

---
 gdb/amd64-windows-tdep.c |    3 +++
 gdb/i386-cygwin-tdep.c   |    3 +++
 gdb/windows-tdep.c       |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 gdb/windows-tdep.h       |    5 +++++
 4 files changed, 57 insertions(+), 0 deletions(-)

diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index 4a40f47..f375409 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -174,6 +174,9 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   set_gdbarch_return_value (gdbarch, amd64_windows_return_value);
   set_gdbarch_skip_main_prologue (gdbarch, amd64_skip_main_prologue);
 
+  set_gdbarch_iterate_over_objfiles_in_search_order
+    (gdbarch, windows_iterate_over_objfiles_in_search_order);
+
   set_solib_ops (gdbarch, &solib_target_so_ops);
 }
 
diff --git a/gdb/i386-cygwin-tdep.c b/gdb/i386-cygwin-tdep.c
index fb940f8..bb395e7 100644
--- a/gdb/i386-cygwin-tdep.c
+++ b/gdb/i386-cygwin-tdep.c
@@ -257,6 +257,9 @@ i386_cygwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   /* Canonical paths on this target look like
      `c:\Program Files\Foo App\mydll.dll', for example.  */
   set_gdbarch_has_dos_based_file_system (gdbarch, 1);
+
+  set_gdbarch_iterate_over_objfiles_in_search_order
+    (gdbarch, windows_iterate_over_objfiles_in_search_order);
 }
 
 static enum gdb_osabi
diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c
index a704599..8c02294 100644
--- a/gdb/windows-tdep.c
+++ b/gdb/windows-tdep.c
@@ -26,6 +26,7 @@
 #include "command.h"
 #include "gdbcmd.h"
 #include "gdbthread.h"
+#include "objfiles.h"
 
 struct cmd_list_element *info_w32_cmdlist;
 
@@ -398,6 +399,51 @@ windows_xfer_shared_library (const char* so_name, CORE_ADDR load_addr,
   obstack_grow_str (obstack, "\"/></library>");
 }
 
+/* Implement the "iterate_over_objfiles_in_search_order" gdbarch
+   method.  It searches all objfiles, starting with CURRENT_OBJFILE
+   first (if not NULL).
+
+   On Windows, the system behaves a little differently when two
+   objfiles each define a global symbol using the same name, compared
+   to other platforms such as GNU/Linux for instance.  On GNU/Linux,
+   all instances of the symbol effectively get merged into a single
+   one, but on Windows, they remain distinct.
+
+   As a result, it usually makes sense to start global symbol searches
+   with the current objfile before expanding it to all other objfiles.
+   This helps for instance when a user debugs some code in a DLL that
+   refers to a global variable defined inside that DLL.  When trying
+   to print the value of that global variable, it would be unhelpful
+   to print the value of another global variable defined with the same
+   name, but in a different DLL.  */
+
+void
+windows_iterate_over_objfiles_in_search_order
+  (struct gdbarch *gdbarch,
+   int (*cb) (struct objfile *objfile, void *cb_data),
+   void *cb_data, struct objfile *current_objfile)
+{
+  int stop;
+  struct objfile *objfile;
+
+  if (current_objfile)
+    {
+      stop = cb (current_objfile, cb_data);
+      if (stop)
+	return;
+    }
+
+  ALL_OBJFILES (objfile)
+    {
+      if (objfile != current_objfile)
+	{
+	  stop = cb (objfile, cb_data);
+	  if (stop)
+	    return;
+	}
+    }
+}
+
 static void
 show_maint_show_all_tib (struct ui_file *file, int from_tty,
 		struct cmd_list_element *c, const char *value)
diff --git a/gdb/windows-tdep.h b/gdb/windows-tdep.h
index c790e0a..81c460f 100644
--- a/gdb/windows-tdep.h
+++ b/gdb/windows-tdep.h
@@ -29,4 +29,9 @@ extern void windows_xfer_shared_library (const char* so_name,
 					 CORE_ADDR load_addr,
 					 struct gdbarch *gdbarch,
 					 struct obstack *obstack);
+
+extern void windows_iterate_over_objfiles_in_search_order
+  (struct gdbarch *gdbarch,
+   int (*cb) (struct objfile *objfile, void *cb_data),
+   void *cb_data, struct objfile *current_objfile);
 #endif
-- 
1.7.1

[RFA/commit 1/3] Revert "Search global symbols from the expression's block objfile first."

[Joel Brobecker]

The search order used in this patch breaks global symbol lookups
for certain symbols when copy-relocation is used.  A slightly different
search order will be implemented later.

gdb/ChangeLog:

        Revert the following patch:
        * findvar.c (default_read_var_value): For LOC_UNRESOLVED symbols,
        try locating the symbol in the symbol's own objfile first, before
        extending the search to all objfiles.
        * symtab.c (lookup_symbol_aux_objfile): New function, extracted
        out of lookup_symbol_aux_symtabs.
        (lookup_symbol_aux_symtabs): Add new parameter "exclude_objfile".
        Replace extracted-out code by call to lookup_symbol_aux_objfile.
        Do not search EXCLUDE_OBJFILE.
        (lookup_static_symbol_aux): Update call to lookup_symbol_aux_symtabs.
        (lookup_symbol_global): Search for matches in the block's objfile
        first, before searching all other objfiles.

Will commit if patches #2 & #3 are OK.

---
 gdb/findvar.c |   10 +-----
 gdb/symtab.c  |  108 +++++++++++++++++----------------------------------------
 2 files changed, 33 insertions(+), 85 deletions(-)

diff --git a/gdb/findvar.c b/gdb/findvar.c
index ed7903c..9009e6f 100644
--- a/gdb/findvar.c
+++ b/gdb/findvar.c
@@ -562,15 +562,7 @@ default_read_var_value (struct symbol *var, struct frame_info *frame)
 	struct minimal_symbol *msym;
 	struct obj_section *obj_section;
 
-	/* First, try locating the associated minimal symbol within
-	   the same objfile.  This prevents us from selecting another
-	   symbol with the same name but located in a different objfile.  */
-	msym = lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var), NULL,
-				      SYMBOL_SYMTAB (var)->objfile);
-	/* If the lookup failed, try expanding the search to all
-	   objfiles.  */
-	if (msym == NULL)
-	  msym = lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var), NULL, NULL);
+	msym = lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var), NULL, NULL);
 	if (msym == NULL)
 	  error (_("No global symbol \"%s\"."), SYMBOL_LINKAGE_NAME (var));
 	if (overlay_debugging)
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 85ddd1d..39d8c6f 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -95,8 +95,7 @@ struct symbol *lookup_symbol_aux_local (const char *name,
 static
 struct symbol *lookup_symbol_aux_symtabs (int block_index,
 					  const char *name,
-					  const domain_enum domain,
-					  struct objfile *exclude_objfile);
+					  const domain_enum domain);
 
 static
 struct symbol *lookup_symbol_aux_quick (struct objfile *objfile,
@@ -1360,7 +1359,7 @@ lookup_static_symbol_aux (const char *name, const domain_enum domain)
   struct objfile *objfile;
   struct symbol *sym;
 
-  sym = lookup_symbol_aux_symtabs (STATIC_BLOCK, name, domain, NULL);
+  sym = lookup_symbol_aux_symtabs (STATIC_BLOCK, name, domain);
   if (sym != NULL)
     return sym;
 
@@ -1499,61 +1498,40 @@ lookup_global_symbol_from_objfile (const struct objfile *main_objfile,
   return NULL;
 }
 
-/* Check to see if the symbol is defined in one of the OBJFILE's
-   symtabs.  BLOCK_INDEX should be either GLOBAL_BLOCK or STATIC_BLOCK,
+/* Check to see if the symbol is defined in one of the symtabs.
+   BLOCK_INDEX should be either GLOBAL_BLOCK or STATIC_BLOCK,
    depending on whether or not we want to search global symbols or
    static symbols.  */
 
 static struct symbol *
-lookup_symbol_aux_objfile (struct objfile *objfile, int block_index,
-			   const char *name, const domain_enum domain)
-{
-  struct symbol *sym = NULL;
-  struct blockvector *bv;
-  const struct block *block;
-  struct symtab *s;
-
-  if (objfile->sf)
-    objfile->sf->qf->pre_expand_symtabs_matching (objfile, block_index,
-						  name, domain);
-
-  ALL_OBJFILE_SYMTABS (objfile, s)
-    if (s->primary)
-      {
-	bv = BLOCKVECTOR (s);
-	block = BLOCKVECTOR_BLOCK (bv, block_index);
-	sym = lookup_block_symbol (block, name, domain);
-	if (sym)
-	  {
-	    block_found = block;
-	    return fixup_symbol_section (sym, objfile);
-	  }
-      }
-
-  return NULL;
-}
-
-/* Same as lookup_symbol_aux_objfile, except that it searches all
-   objfiles except for EXCLUDE_OBJFILE.  Return the first match found.
-
-   If EXCLUDE_OBJFILE is NULL, then all objfiles are searched.  */
-
-static struct symbol *
 lookup_symbol_aux_symtabs (int block_index, const char *name,
-			   const domain_enum domain,
-			   struct objfile *exclude_objfile)
+			   const domain_enum domain)
 {
   struct symbol *sym;
   struct objfile *objfile;
+  struct blockvector *bv;
+  const struct block *block;
+  struct symtab *s;
 
   ALL_OBJFILES (objfile)
   {
-    if (objfile != exclude_objfile)
-      {
-	sym = lookup_symbol_aux_objfile (objfile, block_index, name, domain);
-	if (sym)
-	  return sym;
-      }
+    if (objfile->sf)
+      objfile->sf->qf->pre_expand_symtabs_matching (objfile,
+						    block_index,
+						    name, domain);
+
+    ALL_OBJFILE_SYMTABS (objfile, s)
+      if (s->primary)
+	{
+	  bv = BLOCKVECTOR (s);
+	  block = BLOCKVECTOR_BLOCK (bv, block_index);
+	  sym = lookup_block_symbol (block, name, domain);
+	  if (sym)
+	    {
+	      block_found = block;
+	      return fixup_symbol_section (sym, objfile);
+	    }
+	}
   }
 
   return NULL;
@@ -1679,46 +1657,24 @@ lookup_symbol_global (const char *name,
 		      const domain_enum domain)
 {
   struct symbol *sym = NULL;
-  struct objfile *block_objfile = NULL;
   struct objfile *objfile = NULL;
 
   /* Call library-specific lookup procedure.  */
-  block_objfile = lookup_objfile_from_block (block);
-  if (block_objfile != NULL)
-    sym = solib_global_lookup (block_objfile, name, domain);
+  objfile = lookup_objfile_from_block (block);
+  if (objfile != NULL)
+    sym = solib_global_lookup (objfile, name, domain);
   if (sym != NULL)
     return sym;
 
-  /* If BLOCK_OBJFILE is not NULL, then search this objfile first.
-     In case the global symbol is defined in multiple objfiles,
-     we have a better chance of finding the most relevant symbol.  */
-
-  if (block_objfile != NULL)
-    {
-      sym = lookup_symbol_aux_objfile (block_objfile, GLOBAL_BLOCK,
-				       name, domain);
-      if (sym == NULL)
-	sym = lookup_symbol_aux_quick (block_objfile, GLOBAL_BLOCK,
-				       name, domain);
-      if (sym != NULL)
-	return sym;
-    }
-
-  /* Symbol not found in the BLOCK_OBJFILE, so try all the other
-     objfiles, starting with symtabs first, and then partial symtabs.  */
-
-  sym = lookup_symbol_aux_symtabs (GLOBAL_BLOCK, name, domain, block_objfile);
+  sym = lookup_symbol_aux_symtabs (GLOBAL_BLOCK, name, domain);
   if (sym != NULL)
     return sym;
 
   ALL_OBJFILES (objfile)
   {
-    if (objfile != block_objfile)
-      {
-	sym = lookup_symbol_aux_quick (objfile, GLOBAL_BLOCK, name, domain);
-	if (sym)
-	  return sym;
-      }
+    sym = lookup_symbol_aux_quick (objfile, GLOBAL_BLOCK, name, domain);
+    if (sym)
+      return sym;
   }
 
   return NULL;
-- 
1.7.1

[RFA 0/3] Make global symbol objfile search order arch-dependent

[Joel Brobecker]

Hello,

Re: http://www.sourceware.org/ml/gdb-patches/2012-05/msg01026.html

This patch re-implement objfile searching order to make it gdbarch-
dependent.  There are three patches to this series:

  #1: Reverts my first patch, in order to start from a clean slate.
  #2: Introduces the new gdbarch method, and modifies the relevant
      code to use it, instead of using ALL_OBJFILES.  The gdbarch's
      default implemention, which is equivalent to ALL_OBJFILES,
      is still used for all platforms, so there should be no functional
      change on any platform, yet.
  #3: Introduces a windows-specific version of that new gdbarch
      method, and installs it for x86 and amd64 windows targets.

The patch series has been tested on x86_64-linux, as well as on
x86-windows, but using AdaCore's testsuite.  No regression observed.

Re: [RFA 0/3] Make global symbol objfile search order arch-dependent

[Pedro Alves]

On 05/31/2012 09:36 PM, Joel Brobecker wrote:

> Re: http://www.sourceware.org/ml/gdb-patches/2012-05/msg01026.html
> 
> This patch re-implement objfile searching order to make it gdbarch-
> dependent.  There are three patches to this series:
> 
>   #1: Reverts my first patch, in order to start from a clean slate.
>   #2: Introduces the new gdbarch method, and modifies the relevant
>       code to use it, instead of using ALL_OBJFILES.  The gdbarch's
>       default implemention, which is equivalent to ALL_OBJFILES,
>       is still used for all platforms, so there should be no functional
>       change on any platform, yet.
>   #3: Introduces a windows-specific version of that new gdbarch
>       method, and installs it for x86 and amd64 windows targets.


FWIW, I've read through them, and they look fine to me.

> The patch series has been tested on x86_64-linux, as well as on
> x86-windows, but using AdaCore's testsuite.  No regression observed.


-- 
Pedro Alves

Re: [RFA 3/3] Windows-specific iterate_over_objfiles_in_search_order

[Jan Kratochvil]

On Thu, 31 May 2012 22:36:43 +0200, Joel Brobecker wrote:
>         * amd64-windows-tdep.c (amd64_windows_init_abi): Set
>         iterate_over_objfiles_in_search_order gdbarch method to
>         windows_iterate_over_objfiles_in_search_order.

On Fedora 17 x86_64 with --enable-targets=all I need the patch below.

amd64-windows-tdep.c: In function ‘amd64_windows_init_abi’:
amd64-windows-tdep.c:178:15: error: ‘windows_iterate_over_objfiles_in_search_order’ undeclared (first use in this function)
amd64-windows-tdep.c:178:15: note: each undeclared identifier is reported only once for each function it appears in

I would also prefer to use there in all the definitions/declarations:
typedef int 
  (iterate_over_objfiles_in_search_order_cb_ftype) (struct objfile *objfile, 
                                                    void *cb_data);
(feel free to shorten the name)

It does fix the gdb.fortran/library-module.exp regression here:
-FAIL: gdb.fortran/library-module.exp: print var_i in lib
+PASS: gdb.fortran/library-module.exp: print var_i in lib
-FAIL: gdb.fortran/library-module.exp: print var_i in main
+PASS: gdb.fortran/library-module.exp: print var_i in main

But on Fedora 17 (all x86* archs) it regresses these new testcase, they should
apparently be also made target specific:

-PASS: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from partial symtab
-PASS: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from symtab
+FAIL: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from partial symtab
+FAIL: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from symtab
-PASS: gdb.base/print-file-var.exp: print 'print-file-var-lib2.c'::this_version_id
+FAIL: gdb.base/print-file-var.exp: print 'print-file-var-lib2.c'::this_version_id

 print this_version_num^M
-$3 = 203^M
-(gdb) PASS: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from partial symtab
+$3 = 104^M
+(gdb) FAIL: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from partial symtab
 print this_version_num^M
-$4 = 203^M
-(gdb) PASS: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from symtab
+$4 = 104^M
+(gdb) FAIL: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from symtab
 print 'print-file-var-lib2.c'::this_version_id^M
-$2 = 203^M
-(gdb) PASS: gdb.base/print-file-var.exp: print 'print-file-var-lib2.c'::this_version_id
+$2 = 104^M
+(gdb) FAIL: gdb.base/print-file-var.exp: print 'print-file-var-lib2.c'::this_version_id


Thanks,
Jan


gdb/
2012-06-02  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* amd64-windows-tdep.c: Include windows-tdep.h.

diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index f375409..41e0efa 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -23,6 +23,7 @@
 #include "gdbtypes.h"
 #include "gdbcore.h"
 #include "regcache.h"
+#include "windows-tdep.h"
 
 /* The registers used to pass integer arguments during a function call.  */
 static int amd64_windows_dummy_call_integer_regs[] =

Re: [RFA 3/3] Windows-specific iterate_over_objfiles_in_search_order

[Joel Brobecker]

> amd64-windows-tdep.c: In function ?$B!Famd64_windows_init_abi?$B!G:
> amd64-windows-tdep.c:178:15: error: ?$B!Fwindows_iterate_over_objfiles_in_search_order?$B!G undeclared (first use in this function)

Sorry, I thought I had compiled this file, but apparently not.

> But on Fedora 17 (all x86* archs) it regresses these new testcase, they should
> apparently be also made target specific:
> 
> -PASS: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from partial symtab
> -PASS: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from symtab
> +FAIL: gdb.base/ctxobj.exp: print libctxobj2's this_version_num from partial symtab

Yes, they should. I actually thought I had reverted them, since they
are not in my sandbox. Not sure what happened there, I will double-
check.

> I would also prefer to use there in all the definitions/declarations:
> typedef int 
>   (iterate_over_objfiles_in_search_order_cb_ftype) (struct objfile *objfile, 
>                                                     void *cb_data);

So do I, except that it raised a question: Where should this typedef
be located? It can't really be declared next to the only function
that's going to use it, since this section of the code is generated
on a loop from the data read in gdbarch.sh.  The only real location
I thought was acceptable would be at the start of gdbarch.h. It's
easy to modify gdbarch.sh to add this typedef, but then we create
a maintenance issue where, should we delete this gdbarch method, we
will probably forget to delete the typedef.  This is why I went with
the solution I chose. I'm OK going the other way, but I'd rather be
sure that this is what people want.

-- 
Joel

Re: [RFA 3/3] Windows-specific iterate_over_objfiles_in_search_order

[Jan Kratochvil]

On Sat, 02 Jun 2012 17:32:07 +0200, Joel Brobecker wrote:
> > I would also prefer to use there in all the definitions/declarations:
> > typedef int 
> >   (iterate_over_objfiles_in_search_order_cb_ftype) (struct objfile *objfile, 
> >                                                     void *cb_data);
> 
> So do I, except that it raised a question: Where should this typedef
> be located? It can't really be declared next to the only function
> that's going to use it, since this section of the code is generated
> on a loop from the data read in gdbarch.sh.

OK, why not, there is already that:
extern struct gdbarch *target_gdbarch;


> a maintenance issue where, should we delete this gdbarch method, we
> will probably forget to delete the typedef.

(a) As I do :grep -rw xxx . during such change I believe I would not miss it
and (b) it would not be the first dead source code in GDB.


Thanks,
Jan


diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 5d360af..c166352 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -4245,7 +4245,7 @@ set_gdbarch_info_proc (struct gdbarch *gdbarch,
 }
 
 void
-gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch, int (*cb) (struct objfile *objfile, void *cb_data), void *cb_data, struct objfile *current_objfile)
+gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch, iterate_over_objfiles_in_search_order_cb_ftype *cb, void *cb_data, struct objfile *current_objfile)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->iterate_over_objfiles_in_search_order != NULL);
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index 8bbe0f0..7c13508 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -69,6 +69,11 @@ struct stap_parse_info;
    GDB, this global should be made target-specific.  */
 extern struct gdbarch *target_gdbarch;
 
+/* Callback type for method 'iterate_over_objfiles_in_search_order_ftype'.  */
+typedef int
+  (iterate_over_objfiles_in_search_order_cb_ftype) (struct objfile *objfile,
+                                                    void *cb_data);
+
 
 /* The following are pre-initialized by GDBARCH.  */
 
@@ -1185,8 +1190,8 @@ extern void set_gdbarch_info_proc (struct gdbarch *gdbarch, gdbarch_info_proc_ft
    If not NULL, CURRENT_OBJFILE corresponds to the objfile being
    inspected when the symbol search was requested. */
 
-typedef void (gdbarch_iterate_over_objfiles_in_search_order_ftype) (struct gdbarch *gdbarch, int (*cb) (struct objfile *objfile, void *cb_data), void *cb_data, struct objfile *current_objfile);
-extern void gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch, int (*cb) (struct objfile *objfile, void *cb_data), void *cb_data, struct objfile *current_objfile);
+typedef void (gdbarch_iterate_over_objfiles_in_search_order_ftype) (struct gdbarch *gdbarch, iterate_over_objfiles_in_search_order_cb_ftype *cb, void *cb_data, struct objfile *current_objfile);
+extern void gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch, iterate_over_objfiles_in_search_order_cb_ftype *cb, void *cb_data, struct objfile *current_objfile);
 extern void set_gdbarch_iterate_over_objfiles_in_search_order (struct gdbarch *gdbarch, gdbarch_iterate_over_objfiles_in_search_order_ftype *iterate_over_objfiles_in_search_order);
 
 /* Definition for an unknown syscall, used basically in error-cases.  */
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index 167eb2e..3592b82 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -947,7 +947,7 @@ M:void:info_proc:char *args, enum info_proc_what what:args, what
 #
 # If not NULL, CURRENT_OBJFILE corresponds to the objfile being
 # inspected when the symbol search was requested.
-m:void:iterate_over_objfiles_in_search_order:int (*cb) (struct objfile *objfile, void *cb_data), void *cb_data, struct objfile *current_objfile:cb, cb_data, current_objfile:0:default_iterate_over_objfiles_in_search_order::0
+m:void:iterate_over_objfiles_in_search_order:iterate_over_objfiles_in_search_order_cb_ftype *cb, void *cb_data, struct objfile *current_objfile:cb, cb_data, current_objfile:0:default_iterate_over_objfiles_in_search_order::0
 
 EOF
 }
@@ -1077,6 +1077,11 @@ struct stap_parse_info;
    Eventually, when support for multiple targets is implemented in
    GDB, this global should be made target-specific.  */
 extern struct gdbarch *target_gdbarch;
+
+/* Callback type for method 'iterate_over_objfiles_in_search_order_ftype'.  */
+typedef int
+  (iterate_over_objfiles_in_search_order_cb_ftype) (struct objfile *objfile,
+                                                    void *cb_data);
 EOF
 
 # function typedef's
diff --git a/gdb/objfiles.c b/gdb/objfiles.c
index daa6068..f5e5c75 100644
--- a/gdb/objfiles.c
+++ b/gdb/objfiles.c
@@ -1536,7 +1536,7 @@ gdb_bfd_unref (struct bfd *abfd)
 void
 default_iterate_over_objfiles_in_search_order
   (struct gdbarch *gdbarch,
-   int (*cb) (struct objfile *objfile, void *cb_data),
+   iterate_over_objfiles_in_search_order_cb_ftype *cb,
    void *cb_data, struct objfile *current_objfile)
 {
   int stop = 0;
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index 0c4f723..9f24491 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -528,7 +528,7 @@ extern int gdb_bfd_close_or_warn (struct bfd *abfd);
 
 extern void default_iterate_over_objfiles_in_search_order
   (struct gdbarch *gdbarch,
-   int (*cb) (struct objfile *objfile, void *cb_data),
+   iterate_over_objfiles_in_search_order_cb_ftype *cb,
    void *cb_data, struct objfile *current_objfile);
 \f
 
diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c
index 8c02294..116525c 100644
--- a/gdb/windows-tdep.c
+++ b/gdb/windows-tdep.c
@@ -420,7 +420,7 @@ windows_xfer_shared_library (const char* so_name, CORE_ADDR load_addr,
 void
 windows_iterate_over_objfiles_in_search_order
   (struct gdbarch *gdbarch,
-   int (*cb) (struct objfile *objfile, void *cb_data),
+   iterate_over_objfiles_in_search_order_cb_ftype *cb,
    void *cb_data, struct objfile *current_objfile)
 {
   int stop;
diff --git a/gdb/windows-tdep.h b/gdb/windows-tdep.h
index 81c460f..20bf66d 100644
--- a/gdb/windows-tdep.h
+++ b/gdb/windows-tdep.h
@@ -32,6 +32,6 @@ extern void windows_xfer_shared_library (const char* so_name,
 
 extern void windows_iterate_over_objfiles_in_search_order
   (struct gdbarch *gdbarch,
-   int (*cb) (struct objfile *objfile, void *cb_data),
+   iterate_over_objfiles_in_search_order_cb_ftype *cb,
    void *cb_data, struct objfile *current_objfile);
 #endif

Re: [RFA 3/3] Windows-specific iterate_over_objfiles_in_search_order

[Doug Evans]

On Thu, May 31, 2012 at 1:36 PM, Joel Brobecker <brobecker@adacore.com> wrote:
> This patch sets the windows target to use their own version of
> the iterate_over_objfiles_in_search_order gdbarch method, in
> order to make global symbol searches sensitive to the current
> objfile.
>
> gdb/ChangeLog:
>
>        * windows-tdep.h (windows_iterate_over_objfiles_in_search_order):
>        Add declaration.
>        * windows-tdep.c: #include "objfiles.h".
>        (windows_iterate_over_objfiles_in_search_order): New function.
>        * amd64-windows-tdep.c (amd64_windows_init_abi): Set
>        iterate_over_objfiles_in_search_order gdbarch method to
>        windows_iterate_over_objfiles_in_search_order.
>        * i386-cygwin-tdep.c (i386_cygwin_init_abi): Likewise.
>[...]
>+/* Implement the "iterate_over_objfiles_in_search_order" gdbarch
>+   method.  It searches all objfiles, starting with CURRENT_OBJFILE
>+   first (if not NULL).
>+
>+   On Windows, the system behaves a little differently when two
>+   objfiles each define a global symbol using the same name, compared
>+   to other platforms such as GNU/Linux for instance.  On GNU/Linux,
>+   all instances of the symbol effectively get merged into a single
>+   one, but on Windows, they remain distinct.
>+
>+   As a result, it usually makes sense to start global symbol searches
>+   with the current objfile before expanding it to all other objfiles.
>+   This helps for instance when a user debugs some code in a DLL that
>+   refers to a global variable defined inside that DLL.  When trying
>+   to print the value of that global variable, it would be unhelpful
>+   to print the value of another global variable defined with the same
>+   name, but in a different DLL.  */


GDB's notion of a global symbol isn't a perfect match for ELF's notion.
I'm wondering if there are examples where we'd want this for ELF too.
[And are there examples where we don't want this for ELF?]

Re: [RFA 3/3] Windows-specific iterate_over_objfiles_in_search_order

[Joel Brobecker]

> GDB's notion of a global symbol isn't a perfect match for ELF's notion.
> I'm wondering if there are examples where we'd want this for ELF too.
> [And are there examples where we don't want this for ELF?]

This is definitely one of these issues where we are going through
trials to get GDB to work as best we can. So, your instincts might
be right, but I wouldn't know the answer for sure...

-- 
Joel