Re: [RFA, doc RFA] New option set use-deprecated-index-sections

dje
2012-07-19T18:26:10Z

Eli Zaretskii writes:
> > Date: Thu, 19 Jul 2012 09:27:46 -0700
> > From: Doug Evans <dje@google.com>
> > Cc: Jan Kratochvil <jan.kratochvil@redhat.com>, gdb-patches@sourceware.org
> >
> > On Thu, Jul 19, 2012 at 9:08 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> > >> Date: Thu, 19 Jul 2012 01:33:03 +0200
> > >> From: Jan Kratochvil <jan.kratochvil@redhat.com>
> > >> Cc: gdb-patches@sourceware.org, eliz@gnu.org
> > >>
> > >> On Thu, 19 Jul 2012 00:33:42 +0200, dje@google.com wrote:
> > >> > + use "-iex 'set use-deprecated-index-sections on'".
> > >> [...]
> > >> > +`-iex \"set use-deprecated-index-sections on\"' to gdb."),
> > >>
> > >> It is more Eli's decision but I would find it overquoted.
> > >
> > > How about removing that sentence altogether? We have no reason to
> > > advertise -iex in that particular warning message.
> >
> > I'd like to keep the content of the warning.
>
> The text you suggested is:
>
> warning (_("\
> Skipping deprecated .gdb_index section in %s.\n\
> Do \"set use-deprecated-index-sections on\" to use them anyway.\n\
> This can be done from the command line by passing\n\
> `-iex \"set use-deprecated-index-sections on\"' to gdb."),
> filename);
>
> I'm saying that mentioning the "set" command is enough, no need to
> also say that the command can be invoked through -iex, because _any_
> GDB command can be invoked like that.
>
> That said, I won't argue.

How about this?

2012-07-19 Doug Evans <dje@google.com>

* NEWS: Document new options "set/show use-deprecated-index-sections",
and delete reference to --use-deprecated-index-sections.
* symfile.h (use_deprecated_index_sections): Delete.
* dwarf2read.c (use_deprecated_index_sections): Make static.
(read_index_from_section): Update wording of how to load
deprecated index sections.
(_initialize_dwarf2_read): New options
"set/show use-deprecated-index-sections".
* main.c (captured_main): Delete --use-deprecated-index-sections.

doc/
* gdb.texinfo (Mode Options): Delete --use-deprecated-index-sections.
(Index Files): Document how to control the use of deprecated index
sections.
(Index Section Format): Replace --use-deprecated-index-sections with
"set use-deprecated-index-sections on".

Index: NEWS
===================================================================
RCS file: /cvs/src/src/gdb/NEWS,v
retrieving revision 1.534
diff -u -p -r1.534 NEWS
--- NEWS 18 Jul 2012 04:02:10 -0000 1.534
+++ NEWS 19 Jul 2012 18:15:39 -0000
@@ -114,11 +114,11 @@
* The .gdb_index section has been updated to include symbols for
inlined functions. GDB will ignore older .gdb_index sections by
default, which could cause symbol files to be loaded more slowly
- until their .gdb_index sections can be recreated. The new option
- --use-deprecated-index-sections will cause GDB to use any older
- .gdb_index sections it finds. This will restore performance, but
- the ability to set breakpoints on inlined functions will be lost
- in symbol files with older .gdb_index sections.
+ until their .gdb_index sections can be recreated. The new command
+ "set use-deprecated-index-sections on" will cause GDB to use any older
+ .gdb_index sections it finds. This will restore performance, but the
+ ability to set breakpoints on inlined functions will be lost in symbol
+ files with older .gdb_index sections.

The .gdb_index section has also been updated to record more information
about each symbol. This speeds up the "info variables", "info functions"
@@ -139,6 +139,10 @@

* New commands

+ ** "set use-deprecated-index-sections on|off"
+ "show use-deprecated-index-sections on|off"
+ Controls the use of deprecated .gdb_index sections.
+
** "catch load" and "catch unload" can be used to stop when a shared
library is loaded or unloaded, respectively.

Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.694
diff -u -p -r1.694 dwarf2read.c
--- dwarf2read.c 19 Jul 2012 16:35:48 -0000 1.694
+++ dwarf2read.c 19 Jul 2012 18:15:40 -0000
@@ -85,7 +85,7 @@ static int dwarf2_die_debug = 0;
static int check_physname = 0;

/* When non-zero, do not reject deprecated .gdb_index sections. */
-int use_deprecated_index_sections = 0;
+static int use_deprecated_index_sections = 0;

/* When set, the file that we're processing is known to have debugging
info for C++ namespaces. GCC 3.3.x did not produce this information,
@@ -2611,15 +2611,17 @@ read_index_from_section (struct objfile
Versions earlier than 6 did not emit psymbols for inlined
functions. Using these files will cause GDB not to be able to
set breakpoints on inlined functions by name, so we ignore these
- indices unless the --use-deprecated-index-sections command line
- option was supplied. */
+ indices unless the user has done
+ "set use-deprecated-index-sections on". */
if (version < 6 && !deprecated_ok)
{
static int warning_printed = 0;
if (!warning_printed)
{
- warning (_("Skipping deprecated .gdb_index section in %s, pass "
- "--use-deprecated-index-sections to use them anyway"),
+ warning (_("\
+Skipping deprecated .gdb_index section in %s.\n\
+Do \"set use-deprecated-index-sections on\" before the file is read\n\
+to use the section anyway."),
filename);
warning_printed = 1;
}
@@ -19652,6 +19654,18 @@ the demangler."),
NULL, show_check_physname,
&setdebuglist, &showdebuglist);

+ add_setshow_boolean_cmd ("use-deprecated-index-sections",
+ no_class, &use_deprecated_index_sections, _("\
+Set whether to use deprecated gdb_index sections."), _("\
+Show whether to use deprecated gdb_index sections."), _("\
+When enabled, deprecated .gdb_index sections are used anyway.\n\
+Normally they are ignored either because of a missing feature or\n\
+performance issue.\n\
+Warning: This option must be enabled before gdb reads the file."),
+ NULL,
+ NULL,
+ &setlist, &showlist);
+
c = add_cmd ("gdb-index", class_files, save_gdb_index_command,
_("\
Save a gdb-index file.\n\
Index: main.c
===================================================================
RCS file: /cvs/src/src/gdb/main.c,v
retrieving revision 1.110
diff -u -p -r1.110 main.c
--- main.c 2 Jul 2012 12:05:00 -0000 1.110
+++ main.c 19 Jul 2012 18:15:40 -0000
@@ -471,8 +471,6 @@ captured_main (void *data)
{"args", no_argument, &set_args, 1},
{"l", required_argument, 0, 'l'},
{"return-child-result", no_argument, &return_child_result, 1},
- {"use-deprecated-index-sections", no_argument,
- &use_deprecated_index_sections, 1},
{0, no_argument, 0, 0}
};

Index: symfile.h
===================================================================
RCS file: /cvs/src/src/gdb/symfile.h,v
retrieving revision 1.111
diff -u -p -r1.111 symfile.h
--- symfile.h 18 Jul 2012 23:37:58 -0000 1.111
+++ symfile.h 19 Jul 2012 18:15:40 -0000
@@ -673,9 +673,6 @@ extern void dwarf2_build_frame_info (str

void dwarf2_free_objfile (struct objfile *);

-/* Whether to use deprecated .gdb_index sections. */
-extern int use_deprecated_index_sections;
-
/* From mdebugread.c */

/* Hack to force structures to exist before use in parameter list. */
Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.990
diff -u -p -r1.990 gdb.texinfo
--- doc/gdb.texinfo 5 Jul 2012 01:08:24 -0000 1.990
+++ doc/gdb.texinfo 19 Jul 2012 18:15:41 -0000
@@ -1247,13 +1247,6 @@ memory usage after it completes each com
This option causes @value{GDBN} to print its version number and
no-warranty blurb, and exit.

-@item -use-deprecated-index-sections
-@cindex @code{--use-deprecated-index-sections}
-This option causes @value{GDBN} to read and use deprecated
-@samp{.gdb_index} sections from symbol files. This can speed up
-startup, but may result in some functionality being lost.
-@xref{Index Section Format}.
-
@end table

@node Startup
@@ -16753,6 +16746,28 @@ $ objcopy --add-section .gdb_index=symfi
--set-section-flags .gdb_index=readonly symfile symfile
@end smallexample

+@value{GDBN} will normally ignore older versions of @file{.gdb_index}
+sections that have been deprecated. Usually they are deprecated because
+they are missing a new feature or have performance issues.
+To tell @value{GDBN} to use a deprecated index section anyway
+specify @code{set use-deprecated-index-sections on}.
+The default is @code{off}.
+This can speed up startup, but may result in some functionality being lost.
+@xref{Index Section Format}.
+
+@emph{Warning:} Setting @code{use-deprecated-index-sections} to @code{on}
+must be done before gdb reads the file. The following will not work:
+
+@smallexample
+$ gdb -ex "set use-deprecated-index-sections on" <program>
+@end smallexample
+
+Instead you must do, for example,
+
+@smallexample
+$ gdb -iex "set use-deprecated-index-sections on" <program>
+@end smallexample
+
There are currently some limitation on indices. They only work when
for DWARF debugging information, not stabs. And, they do not
currently work for programs using Ada.
@@ -40408,7 +40423,7 @@ Version 4 uses a different hashing funct
Version 6 includes symbols for inlined functions, whereas versions 4
and 5 do not. Version 7 adds attributes to the CU indices in the
symbol table. @value{GDBN} will only read version 4, 5, or 6 indices
-if the @code{--use-deprecated-index-sections} option is used.
+by specifying @code{set use-deprecated-index-sections on}.

@item
The offset, from the start of the file, of the CU list.