2011-10-06  Doug Evans  <dje@google.com>

	* linux-thread-db.c (thread_db_new_objfile): Only try to load
	libthread_db when we load libpthread or the main symbol file.
	* objfiles.h (OBJF_MAINLINE): Define.
	* symfile.c (symbol_file_add_with_addrs_or_offsets): Pass it to
	allocate_objfile when appropriate.

Index: linux-thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-thread-db.c,v
retrieving revision 1.91
diff -u -p -r1.91 linux-thread-db.c
--- linux-thread-db.c	13 Sep 2011 19:27:01 -0000	1.91
+++ linux-thread-db.c	6 Oct 2011 21:39:32 -0000
@@ -1083,7 +1083,16 @@ thread_db_new_objfile (struct objfile *o
   /* This observer must always be called with inferior_ptid set
      correctly.  */
 
-  if (objfile != NULL)
+  if (objfile != NULL
+      /* Only check for thread_db if we loaded libpthread,
+	 or if this is the main symbol file.
+	 We need to check OBJF_MAINLINE in case this is a statically
+	 linked executable.
+	 For dynamically linked executables, libpthread can be near the end
+	 of the list of shared libraries to load, and in an app of several
+	 thousand shared libraries, this can otherwise be painful.  */
+      && ((objfile->flags & OBJF_MAINLINE) != 0
+	  || libpthread_name_p (objfile->name)))
     check_for_thread_db ();
 }
 
Index: objfiles.h
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.h,v
retrieving revision 1.85
diff -u -p -r1.85 objfiles.h
--- objfiles.h	14 Jun 2011 16:49:41 -0000	1.85
+++ objfiles.h	6 Oct 2011 21:39:32 -0000
@@ -196,7 +196,8 @@ struct objfile
 
     CORE_ADDR addr_low;
 
-    /* Some flag bits for this objfile.  */
+    /* Some flag bits for this objfile.
+       The values are defined by OBJF_*.  */
 
     unsigned short flags;
 
@@ -434,6 +435,11 @@ struct objfile
 
 #define OBJF_PSYMTABS_READ (1 << 4)
 
+/* Set if this is the main symbol file
+   (as opposed to symbol file for dynamically loaded code).  */
+
+#define OBJF_MAINLINE (1 << 5)
+
 /* The object file that contains the runtime common minimal symbols
    for SunOS4.  Note that this objfile has no associated BFD.  */
 
Index: symfile.c
===================================================================
RCS file: /cvs/src/src/gdb/symfile.c,v
retrieving revision 1.316
diff -u -p -r1.316 symfile.c
--- symfile.c	29 Sep 2011 02:04:25 -0000	1.316
+++ symfile.c	6 Oct 2011 21:39:34 -0000
@@ -1084,6 +1084,7 @@ symbol_file_add_with_addrs_or_offsets (b
   const int should_print = ((from_tty || info_verbose)
 			    && (readnow_symbol_files
 				|| (add_flags & SYMFILE_NO_READ) == 0));
+  const int mainline = add_flags & SYMFILE_MAINLINE;
 
   if (readnow_symbol_files)
     {
@@ -1102,7 +1103,7 @@ symbol_file_add_with_addrs_or_offsets (b
       && !query (_("Load new symbol table from \"%s\"? "), name))
     error (_("Not confirmed."));
 
-  objfile = allocate_objfile (abfd, flags);
+  objfile = allocate_objfile (abfd, flags | (mainline ? OBJF_MAINLINE : 0));
   discard_cleanups (my_cleanups);
 
   if (parent)