Avoid expensive complaint calls when complaints are disabled

Running perf on "gdb -nx -readnow -batch gdb", I'm seeing a lot of
time (24%.75!) spent in gettext, via complaints.  'perf report -g' shows:

 -   86.23%     0.00%  gdb      gdb                     [.] gdb_main
    - gdb_main
       - 85.60% catch_command_errors
            symbol_file_add_main_adapter
            symbol_file_add_main
            symbol_file_add_main_1
            symbol_file_add
          - symbol_file_add_with_addrs
             - 84.31% dw2_expand_all_symtabs
                - dw2_instantiate_symtab
                   - 83.79% dw2_do_instantiate_symtab
                      - 70.85% process_die
                         - 41.11% dwarf_decode_macros
                            - 41.09% dwarf_decode_macro_bytes
                               - 39.74% dwarf_decode_macro_bytes
   >>>>>>>>>>>>>>>>>>>>>>>        + 24.75% __dcigettext              <<<<<<<
                                  + 7.37% macro_define_object_internal
                                  + 3.16% macro_define_function
                                    0.77% splay_tree_insert
                                  + 0.76% savestring
                                  + 0.58% free
                                    0.53% read_indirect_string_at_offset_from
                                 0.54% macro_define_object_internal
                                 0.51% macro_start_file
                         + 25.57% process_die
                         + 4.07% dwarf_decode_lines
                      + 4.28% compute_delayed_physnames
                      + 3.85% end_symtab_from_static_block
                      + 3.38% load_cu
                      + 1.29% end_symtab_get_static_block
                   + 0.52% do_my_cleanups
             + 1.29% read_symbols
       + 0.54% gdb_init

The problem is that we're always computing the arguments to pass to
complaint, including passing the format strings through gettext, even
when complaints are disabled.  As seen above, gettext can be quite
expensive.

Fix this by wrapping complaint in a macro that skips the real
complaint call when complaints are disabled.

This improves "gdb -nx -readnow -batch gdb" from
 ~11.0s => ~7.8s with -O2 -g3, and
  ~6.0s => ~5.3s with -O2 -g.
w/ gcc 5.3.1, on x86_64, for me.

gdb/ChangeLog:
2017-11-08  Pedro Alves  <palves@redhat.com>

	* complaints.c (stop_whining): Make extern.
	(complaint): Rename to ...
	(complaint_internal): ... this.
	* complaints.h (complaint): Rename to ...
	(complaint_internal): ... this.
	(complaint): Reimplement as macro around complaint_internal.

gdb/testsuite/ChangeLog:
2017-11-08  Pedro Alves  <palves@redhat.com>

	* gdb.gdb/complaints.exp (test_initial_complaints)
	(test_serial_complaints, test_short_complaints): Call
	complaint_internal instead of complaint.

diff --git a/gdb/complaints.c b/gdb/complaints.c
index 58b6b7b51c3b477de20dd104817436ccd3bb2deb..8fd2f2bbb0168cab7269397bfde707a71a56dc58 100644 (file)
--- a/gdb/complaints.c
+++ b/gdb/complaints.c
@@ -148,7 +148,7 @@ find_complaint (struct complaints *complaints, const char *file,
    before we stop whining about it?  Default is no whining at all,
    since so many systems have ill-constructed symbol files.  */
 
-static int stop_whining = 0;
+int stop_whining = 0;
 
 /* Print a complaint, and link the complaint block into a chain for
    later handling.  */
@@ -236,7 +236,7 @@ vcomplaint (struct complaints **c, const char *file,
 }
 
 void
-complaint (struct complaints **complaints, const char *fmt, ...)
+complaint_internal (struct complaints **complaints, const char *fmt, ...)
 {
   va_list args;
 

diff --git a/gdb/complaints.h b/gdb/complaints.h
index 54c2b18fa4c4db474971c6338238c7b938f113fe..62885e958077496bc939d6323a84d6c700acad26 100644 (file)
--- a/gdb/complaints.h
+++ b/gdb/complaints.h
@@ -28,10 +28,25 @@ struct complaints;
 /* Predefined categories.  */
 extern struct complaints *symfile_complaints;
 
-/* Register a complaint.  */
-extern void complaint (struct complaints **complaints,
-                      const char *fmt,
-                      ...) ATTRIBUTE_PRINTF (2, 3);
+/* Helper for complaint.  */
+extern void complaint_internal (struct complaints **complaints,
+                               const char *fmt, ...)
+  ATTRIBUTE_PRINTF (2, 3);
+
+/* Register a complaint.  This is a macro around complaint_internal to
+   avoid computing complaint's arguments when complaints are disabled.
+   Running FMT via gettext [i.e., _(FMT)] can be quite expensive, for
+   example.  */
+#define complaint(COMPLAINTS, FMT, ...)                                \
+  do                                                           \
+    {                                                          \
+      extern int stop_whining;                                 \
+                                                               \
+      if (stop_whining > 0)                                    \
+       complaint_internal (COMPLAINTS, FMT, ##__VA_ARGS__);    \
+    }                                                          \
+  while (0)
+
 extern void internal_complaint (struct complaints **complaints,
                                const char *file, int line,
                                const char *fmt,

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 2f14e5cf0b4695aafb0de0b83b2b53de63707a1e..634925991773b9d27d31343b3ea61b1a02e0fbfa 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2017-11-08  Pedro Alves  <palves@redhat.com>
+
+       * gdb.gdb/complaints.exp (test_initial_complaints)
+       (test_serial_complaints, test_short_complaints): Call
+       complaint_internal instead of complaint.
+
 2017-11-08  Djordje Todorovic  <djordje.todorovic@rt-rk.com>
 
        * gdb.threads/tls-core.c: New file.

diff --git a/gdb/testsuite/gdb.gdb/complaints.exp b/gdb/testsuite/gdb.gdb/complaints.exp
index c33fb6eb7c28973d5e03eed13a989225c4df1f8e..0b03205b454653220de692af3d6b78c869fc9df6 100644 (file)
--- a/gdb/testsuite/gdb.gdb/complaints.exp
+++ b/gdb/testsuite/gdb.gdb/complaints.exp
@@ -58,16 +58,18 @@ proc test_initial_complaints { } {
     gdb_test "set stop_whining = 2"
 
     # Prime the system
-    gdb_test_stdio "call complaint (&symfile_complaints, \"Register a complaint\")" \
-           "During symbol reading, Register a complaint."
+    gdb_test_stdio \
+       "call complaint_internal (&symfile_complaints, \"Register a complaint\")" \
+       "During symbol reading, Register a complaint."
 
     # Check that the complaint was inserted and where
     gdb_test "print symfile_complaints->root->fmt" \
            ".\[0-9\]+ =.*\"Register a complaint\""
 
     # Re-issue the first message #1
-    gdb_test_stdio "call complaint (&symfile_complaints, symfile_complaints->root->fmt)" \
-           "During symbol reading, Register a complaint."
+    gdb_test_stdio \
+       "call complaint_internal (&symfile_complaints, symfile_complaints->root->fmt)" \
+       "During symbol reading, Register a complaint."
 
     # Check that there is only one thing in the list.  How the boolean
     # result is output depends on whether GDB is built as a C or C++
@@ -76,8 +78,9 @@ proc test_initial_complaints { } {
            ".\[0-9\]+ = \(1|true\)" "list has one entry"
 
     # Add a second complaint, expect it
-    gdb_test_stdio "call complaint (&symfile_complaints, \"Testing! Testing! Testing!\")" \
-           "During symbol reading, Testing. Testing. Testing.."
+    gdb_test_stdio \
+       "call complaint_internal (&symfile_complaints, \"Testing! Testing! Testing!\")" \
+       "During symbol reading, Testing. Testing. Testing.."
 
     return 0
 }
@@ -86,12 +89,14 @@ proc test_serial_complaints { } {
     gdb_test_exact "call clear_complaints (&symfile_complaints, 1, 0)" "" "serial start"
 
     # Prime the system
-    test_complaint "call complaint (&symfile_complaints, \"serial line 1\")" \
+    test_complaint \
+       "call complaint_internal (&symfile_complaints, \"serial line 1\")" \
        "During symbol reading...serial line 1..." \
        "serial line 1"
 
     # Add a second complaint, expect it
-    test_complaint "call complaint (&symfile_complaints, \"serial line 2\")" \
+    test_complaint \
+       "call complaint_internal (&symfile_complaints, \"serial line 2\")" \
        "serial line 2..." \
        "serial line 2"
 
@@ -109,12 +114,14 @@ proc test_short_complaints { } {
     gdb_test_exact "call clear_complaints (&symfile_complaints, 1, 1)" "" "short start"
 
     # Prime the system
-    test_complaint "call complaint (&symfile_complaints, \"short line 1\")" \
+    test_complaint \
+       "call complaint_internal (&symfile_complaints, \"short line 1\")" \
        "short line 1..." \
        "short line 1"
 
     # Add a second complaint, expect it
-    test_complaint "call complaint (&symfile_complaints, \"short line 2\")" \
+    test_complaint \
+       "call complaint_internal (&symfile_complaints, \"short line 2\")" \
        "short line 2..." \
        "short line 2"