2012-07-30  Gary Benson  <gbenson@redhat.com>

	* objfiles.h (inhibit_section_map_updates): New function

	declaration.

	(resume_section_map_updates): Likewise.

	(resume_section_map_updates_cleanup): Likewise.

	* objfiles.c (objfile_pspace_info): New field "inhibit_updates".

	(find_pc_section): Do not update the section map if

	inhibit_updates is set.

	(inhibit_section_map_updates): New function.

	(resume_section_map_updates): Likewise.

	(resume_section_map_updates_cleanup): Likewise.

	* solib-svr4.c (svr4_handle_solib_event): Inhibit section map

	updates for calls to evaluate_probe_argument.

Index: gdb-7.4.91.20120814/gdb/objfiles.h

===================================================================

--- gdb-7.4.91.20120814.orig/gdb/objfiles.h	2012-08-14 17:16:54.000000000 +0200

+++ gdb-7.4.91.20120814/gdb/objfiles.h	2012-08-14 17:20:55.913174609 +0200

@@ -526,6 +526,22 @@ extern void set_objfile_data (struct obj

 extern void *objfile_data (struct objfile *objfile,

 			   const struct objfile_data *data);

+/* In normal use, the section map will be rebuilt by FIND_PC_SECTION

+   if objfiles have been added, removed or relocated since it was last

+   called.  Calling INHIBIT_SECTION_MAP_UPDATES will inhibit this

+   behavior until RESUME_SECTION_MAP_UPDATES is called.  If you call

+   INHIBIT_SECTION_MAP_UPDATES you must ensure that every call to

+   FIND_PC_SECTION in the inhibited region relates to a section that

+   is already in the section map and has not since been removed or

+   relocated.  */

+extern void inhibit_section_map_updates (void);

+

+/* Resume automatically rebuilding the section map as required.  */

+extern void resume_section_map_updates (void);

+

+/* Version of the above suitable for use as a cleanup.  */

+extern void resume_section_map_updates_cleanup (void *arg);

+

 extern void default_iterate_over_objfiles_in_search_order

   (struct gdbarch *gdbarch,

    iterate_over_objfiles_in_search_order_cb_ftype *cb,

Index: gdb-7.4.91.20120814/gdb/objfiles.c

===================================================================

--- gdb-7.4.91.20120814.orig/gdb/objfiles.c	2012-08-14 17:16:55.000000000 +0200

+++ gdb-7.4.91.20120814/gdb/objfiles.c	2012-08-14 17:20:55.915174609 +0200

@@ -70,6 +70,9 @@ struct objfile_pspace_info

   int objfiles_changed_p;

   struct obj_section **sections;

   int num_sections;

+

+  /* Nonzero if section map updates should be inhibited.  */

+  int inhibit_updates;

 };

 /* Per-program-space data key.  */

@@ -1295,7 +1298,7 @@ find_pc_section (CORE_ADDR pc)

     return s;

   pspace_info = get_objfile_pspace_data (current_program_space);

-  if (pspace_info->objfiles_changed_p != 0)

+  if (pspace_info->objfiles_changed_p && !pspace_info->inhibit_updates)

     {

       update_section_map (current_program_space,

 			  &pspace_info->sections,

@@ -1463,6 +1466,30 @@ objfiles_changed (void)

   get_objfile_pspace_data (current_program_space)->objfiles_changed_p = 1;

 }

+/* See comments in objfiles.h.  */

+

+void

+inhibit_section_map_updates (void)

+{

+  get_objfile_pspace_data (current_program_space)->inhibit_updates = 1;

+}

+

+/* See comments in objfiles.h.  */

+

+void

+resume_section_map_updates (void)

+{

+  get_objfile_pspace_data (current_program_space)->inhibit_updates = 0;

+}

+

+/* See comments in objfiles.h.  */

+

+void

+resume_section_map_updates_cleanup (void *arg)

+{

+  resume_section_map_updates ();

+}

+

 /* 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,

Index: gdb-7.4.91.20120814/gdb/solib-svr4.c

===================================================================

--- gdb-7.4.91.20120814.orig/gdb/solib-svr4.c	2012-08-14 17:20:42.000000000 +0200

+++ gdb-7.4.91.20120814/gdb/solib-svr4.c	2012-08-14 17:21:14.090169216 +0200

@@ -1847,6 +1847,7 @@ svr4_handle_solib_event (bpstat bs)

   struct svr4_info *info = get_svr4_info ();

   struct probe_and_info buf, *pi = &buf;

   enum probe_action action;

+  struct cleanup *cleanups = NULL;

   struct value *val;

   LONGEST lmid;

   CORE_ADDR debug_base, lm = 0;

@@ -1870,6 +1871,19 @@ svr4_handle_solib_event (bpstat bs)

   if (action == NAMESPACE_NO_ACTION)

     return;

+  /* EVALUATE_PROBE_ARGUMENT looks up symbols in the dynamic linker

+     using FIND_PC_SECTION.  FIND_PC_SECTION is accelerated by a cache

+     called the section map.  The section map is invalidated every

+     time a shared library is loaded or unloaded, and if the inferior

+     is generating a lot of shared library events then the section map

+     will be updated every time SVR4_HANDLE_SOLIB_EVENT is called.

+     We called FIND_PC_SECTION in SVR4_CREATE_SOLIB_EVENT_BREAKPOINTS,

+     so we can guarantee that the dynamic linker's sections are in the

+     section map.  We can therefore inhibit section map updates across

+     these calls to EVALUATE_PROBE_ARGUMENT and save a lot of time.  */

+  inhibit_section_map_updates ();

+  cleanups = make_cleanup (resume_section_map_updates_cleanup, NULL);

+

   val = evaluate_probe_argument (pi->probe, 0);

   if (val == NULL)

     goto error;

@@ -1901,6 +1915,9 @@ svr4_handle_solib_event (bpstat bs)

 	action = NAMESPACE_RELOAD;

     }

+  do_cleanups (cleanups);

+  cleanups = NULL;

+

   if (action == NAMESPACE_UPDATE_OR_RELOAD)

     {

       if (namespace_update_incremental (info, lmid, lm, is_initial_ns))

@@ -1923,6 +1940,8 @@ svr4_handle_solib_event (bpstat bs)

   warning (_("Probes-based dynamic linker interface failed.\n"

 	     "Reverting to original interface.\n"));

+  if (cleanups != NULL)

+    do_cleanups (cleanups);

   free_namespace_table (info);

   free_probes (info);

   info->using_probes = 0;