New option "set debug symfile on".

	* NEWS: Mention "set debug symfile".
	* Makefile.in (SFILES): Add symfile-debug.c.
	(COMMON_OBS): Add symfile-debug.o.
	* elfread.c (elf_symfile_read): Use objfile_set_sym_fns to set the
	objfile's symbol functions.
	* objfiles.h (objfile_set_sym_fns): Declare.
	* symfile-debug.c: New file.
	* symfile.c (syms_from_objfile_1): Use objfile_set_sym_fns to set the
	objfile's symbol functions.
	(reread_symbols): Ditto.

9 files changed, 810 insertions, 6 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4265e3b6d84..47c28d6d443 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,17 @@
 2013-09-25  Doug Evans  <dje@google.com>
 
+	New option "set debug symfile on".
+	* NEWS: Mention "set debug symfile".
+	* Makefile.in (SFILES): Add symfile-debug.c.
+	(COMMON_OBS): Add symfile-debug.o.
+	* elfread.c (elf_symfile_read): Use objfile_set_sym_fns to set the
+	objfile's symbol functions.
+	* objfiles.h (objfile_set_sym_fns): Declare.
+	* symfile-debug.c: New file.
+	* symfile.c (syms_from_objfile_1): Use objfile_set_sym_fns to set the
+	objfile's symbol functions.
+	(reread_symbols): Ditto.
+
 	* symfile.h (struct sym_fns): Delete member "sym_flavour".
 	All uses updated.
 	(add_symtab_fns): Update prototype.
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 3b0b5c70136..6b8927a9a1c 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -756,7 +756,7 @@ SFILES = ada-exp.y ada-lang.c ada-typeprint.c ada-valprint.c ada-tasks.c \
 	serial.c ser-base.c ser-unix.c skip.c \
 	solib.c solib-target.c source.c \
 	stabsread.c stack.c probe.c stap-probe.c std-regs.c \
-	symfile.c symfile-mem.c symmisc.c symtab.c \
+	symfile.c symfile-debug.c symfile-mem.c symmisc.c symtab.c \
 	target.c target-descriptions.c target-memory.c \
 	thread.c top.c tracepoint.c \
 	trad-frame.c \
@@ -894,7 +894,8 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
 	findvar.o regcache.o cleanups.o \
 	charset.o continuations.o corelow.o disasm.o dummy-frame.o dfp.o \
 	source.o value.o eval.o valops.o valarith.o valprint.o printcmd.o \
-	block.o symtab.o psymtab.o symfile.o symmisc.o linespec.o dictionary.o \
+	block.o symtab.o psymtab.o symfile.o symfile-debug.o symmisc.o \
+	linespec.o dictionary.o \
 	infcall.o \
 	infcmd.o infrun.o \
 	expprint.o environ.o stack.o thread.o \
diff --git a/gdb/NEWS b/gdb/NEWS
index 9f6981c4dbf..b44eb256bcc 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -59,6 +59,11 @@ maint set|show per-command symtab
 
 * New options
 
+set debug symfile off|on
+show debug symfile
+  Control display of debugging info regarding reading symbol files and
+  symbol tables within those files
+
 set print raw frame-arguments
 show print raw frame-arguments
   Set/show whether to print frame arguments in raw mode,
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index f5e4a045057..f5a80d3e78d 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,7 @@
+2013-09-25  Doug Evans  <dje@google.com>
+
+	* gdb.texinfo (Debugging Output): Document set/show debug symfile.
+
 2013-09-16  Stan Shebs  <stan@codesourcery.com>
 
 	Remove the internals manual gdbint.texinfo.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 60d28776509..07d5068797d 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -22573,6 +22573,12 @@ Turns on or off debugging messages for FR-V shared-library code.
 @item show debug solib-frv
 Display the current state of FR-V shared-library code debugging
 messages.
+@item set debug symfile
+@cindex symbol file functions
+Turns on or off display of debugging messages related to symbol file functions.
+The default is off.  @xref{Files}.
+@item show debug symfile
+Show the current state of symbol file debugging messages.
 @item set debug symtab-create
 @cindex symbol table creation
 Turns on or off display of debugging messages related to symbol table creation.
diff --git a/gdb/elfread.c b/gdb/elfread.c
index 3f6fbd97f28..4a3d71312dd 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -1419,14 +1419,14 @@ elf_symfile_read (struct objfile *objfile, int symfile_flags)
 
       if (!objfile_has_partial_symbols (objfile)
 	  && dwarf2_initialize_objfile (objfile))
-	objfile->sf = &elf_sym_fns_gdb_index;
+	objfile_set_sym_fns (objfile, &elf_sym_fns_gdb_index);
       else
 	{
 	  /* It is ok to do this even if the stabs reader made some
 	     partial symbols, because OBJF_PSYMTABS_READ has not been
 	     set, and so our lazy reader function will still be called
 	     when needed.  */
-	  objfile->sf = &elf_sym_fns_lazy_psyms;
+	  objfile_set_sym_fns (objfile, &elf_sym_fns_lazy_psyms);
 	}
     }
   /* If the file has its own symbol tables it has no separate debug
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index 9644784f0fa..72cef502299 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -475,6 +475,9 @@ extern int have_partial_symbols (void);
 
 extern int have_full_symbols (void);
 
+extern void objfile_set_sym_fns (struct objfile *objfile,
+				 const struct sym_fns *sf);
+
 extern void objfiles_changed (void);
 
 /* This operation deletes all objfile entries that represent solibs that
diff --git a/gdb/symfile-debug.c b/gdb/symfile-debug.c
new file mode 100644
index 00000000000..b6e84d1687a
--- /dev/null
+++ b/gdb/symfile-debug.c
@@ -0,0 +1,773 @@
+/* Debug logging for the symbol file functions for the GNU debugger, GDB.
+
+   Copyright (C) 2013 Free Software Foundation, Inc.
+
+   Contributed by Cygnus Support, using pieces from other GDB modules.
+
+   This file is part of GDB.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+
+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Note: Be careful with functions that can throw errors.
+   We want to see a logging message regardless of whether an error was thrown.
+   This typically means printing a message before calling the real function
+   and then if the function returns a result printing a message after it
+   returns.  */
+
+#include "defs.h"
+#include "gdbcmd.h"
+#include "objfiles.h"
+#include "observer.h"
+#include "source.h"
+#include "symtab.h"
+#include "symfile.h"
+
+/* We need to save a pointer to the real symbol functions.
+   Plus, the debug versions are malloc'd because we have to NULL out the
+   ones that are NULL in the real copy.  */
+
+struct debug_sym_fns_data
+{
+  const struct sym_fns *real_sf;
+  struct sym_fns debug_sf;
+};
+
+/* We need to record a pointer to the real set of functions for each
+   objfile.  */
+static const struct objfile_data *symfile_debug_objfile_data_key;
+
+/* If non-zero all calls to the symfile functions are logged.  */
+static int debug_symfile = 0;
+
+/* Return non-zero if symfile debug logging is installed.  */
+
+static int
+symfile_debug_installed (struct objfile *objfile)
+{
+  return (objfile->sf != NULL
+	  && objfile_data (objfile, symfile_debug_objfile_data_key) != NULL);
+}
+
+/* Utility to return the name to print for OBJFILE.  */
+
+static const char *
+debug_objfile_name (const struct objfile *objfile)
+{
+  return lbasename (objfile->original_name);
+}
+
+/* Utility return the name to print for SYMTAB.  */
+
+static const char *
+debug_symtab_name (struct symtab *symtab)
+{
+  return symtab_to_filename_for_display (symtab);
+}
+
+/* Debugging version of struct quick_symbol_functions.  */
+
+static int
+debug_qf_has_symbols (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  int retval;
+
+  retval = debug_data->real_sf->qf->has_symbols (objfile);
+
+  fprintf_filtered (gdb_stdlog, "qf->has_symbols (%s) = %d\n",
+		    debug_objfile_name (objfile), retval);
+
+  return retval;
+}
+
+static struct symtab *
+debug_qf_find_last_source_symtab (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  struct symtab *retval;
+
+  fprintf_filtered (gdb_stdlog, "qf->find_last_source_symtab (%s)\n",
+		    debug_objfile_name (objfile));
+
+  retval = debug_data->real_sf->qf->find_last_source_symtab (objfile);
+
+  fprintf_filtered (gdb_stdlog, "qf->find_last_source_symtab (...) = %s\n",
+		    retval ? debug_symtab_name (retval) : "NULL");
+
+  return retval;
+}
+
+static void
+debug_qf_forget_cached_source_info (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "qf->forget_cached_source_info (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->qf->forget_cached_source_info (objfile);
+}
+
+static int
+debug_qf_map_symtabs_matching_filename (struct objfile *objfile,
+					const char *name,
+					const char *real_path,
+					int (*callback) (struct symtab *,
+							 void *),
+					void *data)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  int retval;
+
+  fprintf_filtered (gdb_stdlog,
+		    "qf->map_symtabs_matching_filename (%s, \"%s\", \"%s\", %s, %s)\n",
+		    debug_objfile_name (objfile), name,
+		    real_path ? real_path : NULL,
+		    host_address_to_string (callback),
+		    host_address_to_string (data));
+
+  retval = debug_data->real_sf->qf->map_symtabs_matching_filename
+    (objfile, name, real_path, callback, data);
+
+  fprintf_filtered (gdb_stdlog,
+		    "qf->map_symtabs_matching_filename (...) = %d\n",
+		    retval);
+
+  return retval;
+}
+
+static struct symtab *
+debug_qf_lookup_symbol (struct objfile *objfile, int kind, const char *name,
+			domain_enum domain)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  struct symtab *retval;
+
+  fprintf_filtered (gdb_stdlog,
+		    "qf->lookup_symbol (%s, %d, \"%s\", %s)\n",
+		    debug_objfile_name (objfile), kind, name,
+		    domain_name (domain));
+
+  retval = debug_data->real_sf->qf->lookup_symbol (objfile, kind, name,
+						   domain);
+
+  fprintf_filtered (gdb_stdlog, "qf->lookup_symbol (...) = %s\n",
+		    retval ? debug_symtab_name (retval) : "NULL");
+
+  return retval;
+}
+
+static void
+debug_qf_print_stats (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "qf->print_stats (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->qf->print_stats (objfile);
+}
+
+static void
+debug_qf_dump (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "qf->dump (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->qf->dump (objfile);
+}
+
+static void
+debug_qf_relocate (struct objfile *objfile,
+		   const struct section_offsets *new_offsets,
+		   const struct section_offsets *delta)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "qf->relocate (%s, %s, %s)\n",
+		    debug_objfile_name (objfile),
+		    host_address_to_string (new_offsets),
+		    host_address_to_string (delta));
+
+  debug_data->real_sf->qf->relocate (objfile, new_offsets, delta);
+}
+
+static void
+debug_qf_expand_symtabs_for_function (struct objfile *objfile,
+				      const char *func_name)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog,
+		    "qf->expand_symtabs_for_function (%s, \"%s\")\n",
+		    debug_objfile_name (objfile), func_name);
+
+  debug_data->real_sf->qf->expand_symtabs_for_function (objfile, func_name);
+}
+
+static void
+debug_qf_expand_all_symtabs (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "qf->expand_all_symtabs (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->qf->expand_all_symtabs (objfile);
+}
+
+static void
+debug_qf_expand_symtabs_with_fullname (struct objfile *objfile,
+				       const char *fullname)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog,
+		    "qf->expand_symtabs_with_fullname (%s, \"%s\")\n",
+		    debug_objfile_name (objfile), fullname);
+
+  debug_data->real_sf->qf->expand_symtabs_with_fullname (objfile, fullname);
+}
+
+static void
+debug_qf_map_matching_symbols (struct objfile *objfile,
+			       const char *name, domain_enum namespace,
+			       int global,
+			       int (*callback) (struct block *,
+						struct symbol *, void *),
+			       void *data,
+			       symbol_compare_ftype *match,
+			       symbol_compare_ftype *ordered_compare)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog,
+		    "qf->map_matching_symbols (%s, \"%s\", %s, %d, %s, %s, %s, %s)\n",
+		    debug_objfile_name (objfile), name,
+		    domain_name (namespace), global,
+		    host_address_to_string (callback),
+		    host_address_to_string (data),
+		    host_address_to_string (match),
+		    host_address_to_string (ordered_compare));
+
+  debug_data->real_sf->qf->map_matching_symbols (objfile, name,
+						 namespace, global,
+						 callback, data,
+						 match,
+						 ordered_compare);
+}
+
+static void
+debug_qf_expand_symtabs_matching (struct objfile *objfile,
+				  int (*file_matcher) (const char *, void *,
+						       int basenames),
+				  int (*name_matcher) (const char *, void *),
+				  enum search_domain kind,
+				  void *data)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog,
+		    "qf->expand_symtabs_matching (%s, %s, %s, %s, %s)\n",
+		    debug_objfile_name (objfile),
+		    host_address_to_string (file_matcher),
+		    host_address_to_string (name_matcher),
+		    search_domain_name (kind),
+		    host_address_to_string (data));
+
+  debug_data->real_sf->qf->expand_symtabs_matching (objfile,
+						    file_matcher,
+						    name_matcher,
+						    kind, data);
+}
+
+static struct symtab *
+debug_qf_find_pc_sect_symtab (struct objfile *objfile,
+			      struct minimal_symbol *msymbol,
+			      CORE_ADDR pc,
+			      struct obj_section *section,
+			      int warn_if_readin)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  struct symtab *retval;
+
+  fprintf_filtered (gdb_stdlog,
+		    "qf->find_pc_sect_symtab (%s, %s, %s, %s, %d)\n",
+		    debug_objfile_name (objfile),
+		    host_address_to_string (msymbol),
+		    hex_string (pc),
+		    host_address_to_string (section),
+		    warn_if_readin);
+
+  retval = debug_data->real_sf->qf->find_pc_sect_symtab (objfile, msymbol,
+							 pc, section,
+							 warn_if_readin);
+
+  fprintf_filtered (gdb_stdlog, "qf->find_pc_sect_symtab (...) = %s\n",
+		    retval ? debug_symtab_name (retval) : "NULL");
+
+  return retval;
+}
+
+static void
+debug_qf_map_symbol_filenames (struct objfile *objfile,
+			       symbol_filename_ftype *fun, void *data,
+			       int need_fullname)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  fprintf_filtered (gdb_stdlog,
+		    "qf->map_symbol_filenames (%s, %s, %s, %d)\n",
+		    debug_objfile_name (objfile),
+		    host_address_to_string (fun),
+		    host_address_to_string (data),
+		    need_fullname);
+
+  debug_data->real_sf->qf->map_symbol_filenames (objfile, fun, data,
+						 need_fullname);
+}
+
+static const struct quick_symbol_functions debug_sym_quick_functions =
+{
+  debug_qf_has_symbols,
+  debug_qf_find_last_source_symtab,
+  debug_qf_forget_cached_source_info,
+  debug_qf_map_symtabs_matching_filename,
+  debug_qf_lookup_symbol,
+  debug_qf_print_stats,
+  debug_qf_dump,
+  debug_qf_relocate,
+  debug_qf_expand_symtabs_for_function,
+  debug_qf_expand_all_symtabs,
+  debug_qf_expand_symtabs_with_fullname,
+  debug_qf_map_matching_symbols,
+  debug_qf_expand_symtabs_matching,
+  debug_qf_find_pc_sect_symtab,
+  debug_qf_map_symbol_filenames
+};
+
+/* Debugging version of struct sym_probe_fns.  */
+
+static VEC (probe_p) *
+debug_sym_get_probes (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  VEC (probe_p) *retval;
+
+  retval = debug_data->real_sf->sym_probe_fns->sym_get_probes (objfile);
+
+  fprintf_filtered (gdb_stdlog,
+		    "probes->sym_get_probes (%s) = %s\n",
+		    debug_objfile_name (objfile),
+		    host_address_to_string (retval));
+
+  return retval;
+}
+
+static unsigned
+debug_sym_get_probe_argument_count (struct probe *probe)
+{
+  struct objfile *objfile = probe->objfile;
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  unsigned retval;
+
+  retval = debug_data->real_sf->sym_probe_fns->sym_get_probe_argument_count
+    (probe);
+
+  fprintf_filtered (gdb_stdlog,
+		    "probes->sym_get_probe_argument_count (%s) = %u\n",
+		    host_address_to_string (probe), retval);
+
+  return retval;
+}
+
+static int
+debug_can_evaluate_probe_arguments (struct probe *probe)
+{
+  struct objfile *objfile = probe->objfile;
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  int retval;
+
+  retval = debug_data->real_sf->sym_probe_fns->can_evaluate_probe_arguments
+    (probe);
+
+  fprintf_filtered (gdb_stdlog,
+		    "probes->can_evaluate_probe_arguments (%s) = %d\n",
+		    host_address_to_string (probe), retval);
+
+  return retval;
+}
+
+static struct value *
+debug_sym_evaluate_probe_argument (struct probe *probe, unsigned n)
+{
+  struct objfile *objfile = probe->objfile;
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  struct value *retval;
+
+  fprintf_filtered (gdb_stdlog,
+		    "probes->sym_evaluate_probe_argument (%s, %u)\n",
+		    host_address_to_string (probe), n);
+
+  retval = debug_data->real_sf->sym_probe_fns->sym_evaluate_probe_argument
+    (probe, n);
+
+  fprintf_filtered (gdb_stdlog,
+		    "probes->sym_evaluate_probe_argument (...) = %s\n",
+		    host_address_to_string (retval));
+
+  return retval;
+}
+
+static void
+debug_sym_compile_to_ax (struct probe *probe, struct agent_expr *expr,
+			 struct axs_value *value, unsigned n)
+{
+  struct objfile *objfile = probe->objfile;
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog,
+		    "probes->sym_compile_to_ax (%s, %s, %s, %u)\n",
+		    host_address_to_string (probe),
+		    host_address_to_string (expr),
+		    host_address_to_string (value), n);
+
+  debug_data->real_sf->sym_probe_fns->sym_compile_to_ax
+    (probe, expr, value, n);
+}
+
+static void
+debug_sym_relocate_probe (struct objfile *objfile,
+			  const struct section_offsets *new_offsets,
+			  const struct section_offsets *delta)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog,
+		    "probes->sym_relocate_probe (%s, %s, %s)\n",
+		    debug_objfile_name (objfile),
+		    host_address_to_string (new_offsets),
+		    host_address_to_string (delta));
+
+  debug_data->real_sf->sym_probe_fns->sym_relocate_probe
+    (objfile, new_offsets, delta);
+}
+
+static const struct sym_probe_fns debug_sym_probe_fns =
+{
+  debug_sym_get_probes,
+  debug_sym_get_probe_argument_count,
+  debug_can_evaluate_probe_arguments,
+  debug_sym_evaluate_probe_argument,
+  debug_sym_compile_to_ax,
+  debug_sym_relocate_probe
+};
+
+/* Debugging version of struct sym_fns.  */
+
+static void
+debug_sym_new_init (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "sf->sym_new_init (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->sym_new_init (objfile);
+}
+
+static void
+debug_sym_init (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "sf->sym_init (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->sym_init (objfile);
+}
+
+static void
+debug_sym_read (struct objfile *objfile, int symfile_flags)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "sf->sym_read (%s, 0x%x)\n",
+		    debug_objfile_name (objfile), symfile_flags);
+
+  debug_data->real_sf->sym_read (objfile, symfile_flags);
+}
+
+static void
+debug_sym_read_psymbols (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "sf->sym_read_psymbols (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->sym_read_psymbols (objfile);
+}
+
+static void
+debug_sym_finish (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "sf->sym_finish (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->sym_finish (objfile);
+}
+
+static void
+debug_sym_offsets (struct objfile *objfile,
+		   const struct section_addr_info *info)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "sf->sym_offsets (%s, %s)\n",
+		    debug_objfile_name (objfile),
+		    host_address_to_string (info));
+
+  debug_data->real_sf->sym_offsets (objfile, info);
+}
+
+static struct symfile_segment_data *
+debug_sym_segments (bfd *abfd)
+{
+  /* This API function is annoying, it doesn't take a "this" pointer.
+     Fortunately it is only used in one place where we (re-)lookup the
+     sym_fns table to use.  Thus we will never be called.  */
+  gdb_assert_not_reached ("debug_sym_segments called");
+}
+
+static void
+debug_sym_read_linetable (struct objfile *objfile)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  fprintf_filtered (gdb_stdlog, "sf->sym_read_linetable (%s)\n",
+		    debug_objfile_name (objfile));
+
+  debug_data->real_sf->sym_read_linetable (objfile);
+}
+
+static bfd_byte *
+debug_sym_relocate (struct objfile *objfile, asection *sectp, bfd_byte *buf)
+{
+  const struct debug_sym_fns_data *debug_data =
+    objfile_data (objfile, symfile_debug_objfile_data_key);
+  bfd_byte *retval;
+
+  retval = debug_data->real_sf->sym_relocate (objfile, sectp, buf);
+
+  fprintf_filtered (gdb_stdlog,
+		    "sf->sym_relocate (%s, %s, %s) = %s\n",
+		    debug_objfile_name (objfile),
+		    host_address_to_string (sectp),
+		    host_address_to_string (buf),
+		    host_address_to_string (retval));
+
+  return retval;
+}
+
+/* Template of debugging version of struct sym_fns.
+   A copy is made, with sym_flavour updated, and a pointer to the real table
+   installed in real_sf, and then a pointer to the copy is installed in the
+   objfile.  */
+
+static const struct sym_fns debug_sym_fns =
+{
+  debug_sym_new_init,
+  debug_sym_init,
+  debug_sym_read,
+  debug_sym_read_psymbols,
+  debug_sym_finish,
+  debug_sym_offsets,
+  debug_sym_segments,
+  debug_sym_read_linetable,
+  debug_sym_relocate,
+  &debug_sym_probe_fns,
+  &debug_sym_quick_functions
+};
+
+/* Free the copy of sym_fns recorded in the registry.  */
+
+static void
+symfile_debug_free_objfile (struct objfile *objfile, void *datum)
+{
+  xfree (datum);
+}
+
+/* Install the debugging versions of the symfile functions for OBJFILE.
+   Do not call this if the debug versions are already installed.  */
+
+static void
+install_symfile_debug_logging (struct objfile *objfile)
+{
+  const struct sym_fns *real_sf;
+  struct debug_sym_fns_data *debug_data;
+
+  /* The debug versions should not already be installed.  */
+  gdb_assert (!symfile_debug_installed (objfile));
+
+  real_sf = objfile->sf;
+
+  /* Alas we have to preserve NULL entries in REAL_SF.  */
+  debug_data = XZALLOC (struct debug_sym_fns_data);
+
+#define COPY_SF_PTR(from, to, name, func)	\
+  do {						\
+    if ((from)->name)				\
+      (to)->debug_sf.name = func;		\
+  } while (0)
+
+  COPY_SF_PTR (real_sf, debug_data, sym_new_init, debug_sym_new_init);
+  COPY_SF_PTR (real_sf, debug_data, sym_init, debug_sym_init);
+  COPY_SF_PTR (real_sf, debug_data, sym_read, debug_sym_read);
+  COPY_SF_PTR (real_sf, debug_data, sym_read_psymbols,
+	       debug_sym_read_psymbols);
+  COPY_SF_PTR (real_sf, debug_data, sym_finish, debug_sym_finish);
+  COPY_SF_PTR (real_sf, debug_data, sym_offsets, debug_sym_offsets);
+  COPY_SF_PTR (real_sf, debug_data, sym_segments, debug_sym_segments);
+  COPY_SF_PTR (real_sf, debug_data, sym_read_linetable,
+	       debug_sym_read_linetable);
+  COPY_SF_PTR (real_sf, debug_data, sym_relocate, debug_sym_relocate);
+  if (real_sf->sym_probe_fns)
+    debug_data->debug_sf.sym_probe_fns = &debug_sym_probe_fns;
+  debug_data->debug_sf.qf = &debug_sym_quick_functions;
+
+#undef COPY_SF_PTR
+
+  debug_data->real_sf = real_sf;
+  set_objfile_data (objfile, symfile_debug_objfile_data_key, debug_data);
+  objfile->sf = &debug_data->debug_sf;
+}
+
+/* Uninstall the debugging versions of the symfile functions for OBJFILE.
+   Do not call this if the debug versions are not installed.  */
+
+static void
+uninstall_symfile_debug_logging (struct objfile *objfile)
+{
+  struct debug_sym_fns_data *debug_data;
+
+  /* The debug versions should be currently installed.  */
+  gdb_assert (symfile_debug_installed (objfile));
+
+  debug_data = objfile_data (objfile, symfile_debug_objfile_data_key);
+
+  objfile->sf = debug_data->real_sf;
+  xfree (debug_data);
+  set_objfile_data (objfile, symfile_debug_objfile_data_key, NULL);
+}
+
+/* Call this function to set OBJFILE->SF.
+   Do not set OBJFILE->SF directly.  */
+
+void
+objfile_set_sym_fns (struct objfile *objfile, const struct sym_fns *sf)
+{
+  if (symfile_debug_installed (objfile))
+    {
+      gdb_assert (debug_symfile);
+      /* Remove the current one, and reinstall a new one later.  */
+      uninstall_symfile_debug_logging (objfile);
+    }
+
+  /* Assume debug logging is disabled.  */
+  objfile->sf = sf;
+
+  /* Turn debug logging on if enabled.  */
+  if (debug_symfile)
+    install_symfile_debug_logging (objfile);
+}
+
+static void
+set_debug_symfile (char *args, int from_tty, struct cmd_list_element *c)
+{
+  struct program_space *pspace;
+  struct objfile *objfile;
+
+  ALL_PSPACES (pspace)
+    ALL_PSPACE_OBJFILES (pspace, objfile)
+    {
+      if (debug_symfile)
+	{
+	  if (!symfile_debug_installed (objfile))
+	    install_symfile_debug_logging (objfile);
+	}
+      else
+	{
+	  if (symfile_debug_installed (objfile))
+	    uninstall_symfile_debug_logging (objfile);
+	}
+    }
+}
+
+static void
+show_debug_symfile (struct ui_file *file, int from_tty,
+			struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("Symfile debugging is %s.\n"), value);
+}
+
+initialize_file_ftype _initialize_symfile_debug;
+
+void
+_initialize_symfile_debug (void)
+{
+  symfile_debug_objfile_data_key
+    = register_objfile_data_with_cleanup (NULL, symfile_debug_free_objfile);
+
+  add_setshow_boolean_cmd ("symfile", no_class, &debug_symfile, _("\
+Set debugging of the symfile functions."), _("\
+Show debugging of the symfile functions."), _("\
+When enabled, all calls to the symfile functions are logged."),
+			   set_debug_symfile, show_debug_symfile,
+			   &setdebuglist, &showdebuglist);
+
+  /* Note: We don't need a new-objfile observer because debug logging
+     will be installed when objfile init'n calls objfile_set_sym_fns.  */
+}
diff --git a/gdb/symfile.c b/gdb/symfile.c
index 9bb3c55a057..ecf4e328358 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -940,7 +940,7 @@ syms_from_objfile_1 (struct objfile *objfile,
   struct cleanup *old_chain;
   const int mainline = add_flags & SYMFILE_MAINLINE;
 
-  objfile->sf = find_sym_fns (objfile->obfd);
+  objfile_set_sym_fns (objfile, find_sym_fns (objfile->obfd));
 
   if (objfile->sf == NULL)
     {
@@ -2530,7 +2530,7 @@ reread_symbols (void)
 	  /* Reset the sym_fns pointer.  The ELF reader can change it
 	     based on whether .gdb_index is present, and we need it to
 	     start over.  PR symtab/15885  */
-	  objfile->sf = find_sym_fns (objfile->obfd);
+	  objfile_set_sym_fns (objfile, find_sym_fns (objfile->obfd));
 
 	  build_objfile_section_table (objfile);
 	  terminate_minimal_symbol_table (objfile);