From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10076 invoked by alias); 27 Jan 2014 08:09:49 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 9989 invoked by uid 89); 27 Jan 2014 08:09:48 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.6 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 X-HELO: rock.gnat.com Received: from rock.gnat.com (HELO rock.gnat.com) (205.232.38.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-SHA encrypted) ESMTPS; Mon, 27 Jan 2014 08:09:44 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id B96501164D8 for ; Mon, 27 Jan 2014 03:09:42 -0500 (EST) Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 7I1ymHzgB9bu for ; Mon, 27 Jan 2014 03:09:42 -0500 (EST) Received: from joel.gnat.com (localhost.localdomain [127.0.0.1]) by rock.gnat.com (Postfix) with ESMTP id 410CA11649F for ; Mon, 27 Jan 2014 03:09:42 -0500 (EST) Received: by joel.gnat.com (Postfix, from userid 1000) id 94014E14CA; Mon, 27 Jan 2014 08:36:57 +0400 (RET) From: Joel Brobecker To: gdb-patches@sourceware.org Subject: [Ada/NEWS+doco] New Ada maintenance command to ignore descriptive types (DWARF). Date: Mon, 27 Jan 2014 08:09:00 -0000 Message-Id: <1390797415-6071-1-git-send-email-brobecker@adacore.com> X-SW-Source: 2014-01/txt/msg00978.txt.bz2 Hello, Currently, Ada debugging requires the use of certain GNAT-specific encodings, which are generated by the compiler. These encodings were created a long time ago to work around the fairly limited capabilities of the stabs debugging format. With DWARF, the vast majority of the encodings could be abandoned in favor of a pure DWARF approach. In order to make it easier to evaluate the quality of the DWARF debugging information generated by the compiler, and how the debugger handles it, we are introducing a small Ada-specific maintenance setting which changes the debugger's behavior to ignore descriptive types. Descriptive types are artificial types generated by the compiler purely to give the debugger hints as to how to properly decode certain properties of a type. For instance, for array types, it generates a parallel type whose name is the name of the array suffixed with ___XA, whose contents tells us what the array's index type is, and possibly its bounds. See GCC's gcc/ada/exp_dbug.ads for the full description of all encodings. This is only a first step, as this setting does not deactivate all encodings; More settings dedicated to each type of encoding will likely be implemented in the future, as we make progress. gdb/ChangeLog: * ada-lang.c (maint_set_ada_cmdlist, maint_show_ada_cmdlist): New static globals. (maint_set_ada_cmd, maint_show_ada_cmd): New functions. (ada_ignore_descriptive_types_p): New static global. (find_parallel_type_by_descriptive_type): Return immediately if ada_ignore_descriptive_types_p is set. (_initialize_ada_language): Register new commands "maintenance set ada", "maintenance show ada", "maintenance set ada ignore-descriptive-types" and "maintenance show ada ignore-descriptive-types". * NEWS: Add entry for new "maint ada set/show ignore-descriptive-types" commands. gdb/doc/ChangeLog: * gdb.texinfo (Ada Glitches): Document the new "maint ada set/show ignore-descriptive-types". commands. OK for the documentation part (including the help of the new commands)? Thank you, -- Joel --- gdb/NEWS | 9 +++++++++ gdb/ada-lang.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ gdb/doc/gdb.texinfo | 31 +++++++++++++++++++++++++++++++ 3 files changed, 88 insertions(+) diff --git a/gdb/NEWS b/gdb/NEWS index 6b1aacb..af7fcd0 100644 --- a/gdb/NEWS +++ b/gdb/NEWS @@ -3,6 +3,15 @@ *** Changes since GDB 7.7 +* New options + +maint ada set ignore-descriptive-types (on|off) +maint ada show ignore-descriptive-types + Control whether the debugger should ignore descriptive types. + The default is to use the descriptive types. See the user manual + for more details on descriptive types and the intended usage of + this option. + * New features in the GDB remote stub, GDBserver ** New option --debug-format=option1[,option2,...] allows one to add diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c index 2630456..cad480f 100644 --- a/gdb/ada-lang.c +++ b/gdb/ada-lang.c @@ -308,6 +308,31 @@ static const char *known_auxiliary_function_name_patterns[] = { /* Space for allocating results of ada_lookup_symbol_list. */ static struct obstack symbol_list_obstack; +/* Maintenance-related settings for this module. */ + +static struct cmd_list_element *maint_set_ada_cmdlist; +static struct cmd_list_element *maint_show_ada_cmdlist; + +/* Implement the "maintenance set ada" (prefix) command. */ + +static void +maint_set_ada_cmd (char *args, int from_tty) +{ + help_list (maint_set_ada_cmdlist, "maintenance set ada ", -1, gdb_stdout); +} + +/* Implement the "maintenance show ada" (prefix) command. */ + +static void +maint_show_ada_cmd (char *args, int from_tty) +{ + cmd_show_list (maint_show_ada_cmdlist, from_tty, ""); +} + +/* The "maintenance ada set/show ignore-descriptive-type" value. */ + +static int ada_ignore_descriptive_types_p = 0; + /* Inferior-specific data. */ /* Per-inferior data for this module. */ @@ -7422,6 +7447,9 @@ find_parallel_type_by_descriptive_type (struct type *type, const char *name) { struct type *result; + if (ada_ignore_descriptive_types_p) + return NULL; + /* If there no descriptive-type info, then there is no parallel type to be found. */ if (!HAVE_GNAT_AUX_INFO (type)) @@ -13321,6 +13349,26 @@ List all Ada exception names.\n\ If a regular expression is passed as an argument, only those matching\n\ the regular expression are listed.")); + add_prefix_cmd ("ada", class_maintenance, maint_set_ada_cmd, + _("Set Ada maintenance-related variables."), + &maint_set_ada_cmdlist, "maintenance set ada ", + 0/*allow-unknown*/, &maintenance_set_cmdlist); + + add_prefix_cmd ("ada", class_maintenance, maint_show_ada_cmd, + _("Show Ada maintenance-related variables"), + &maint_show_ada_cmdlist, "maintenance show ada ", + 0/*allow-unknown*/, &maintenance_show_cmdlist); + + add_setshow_boolean_cmd + ("ignore-descriptive-types", class_maintenance, + &ada_ignore_descriptive_types_p, + _("Set whether descriptive types generated by GNAT should be ignored."), + _("Show whether descriptive types generated by GNAT should be ignored."), + _("\ +When enabled, the debugger will stop using the DW_AT_GNAT_descriptive_type\n\ +DWARF attribute."), + NULL, NULL, &maint_set_ada_cmdlist, &maint_show_ada_cmdlist); + obstack_init (&symbol_list_obstack); decoded_names_store = htab_create_alloc diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index a990d2a..f52f520 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -15712,6 +15712,37 @@ recommended to leave this setting to @code{on} unless necessary. @end table +Internally, the debugger also relies on the compiler following a number +of conventions known as the @samp{GNAT Encoding}, all documented in +@file{gcc/ada/exp_dbug.ads} in the GCC sources. This encoding describes +how the debugging information should be generated for certain types. +In particular, this convention makes use of @samp{descriptive types}, +which are artificial types generated purely to help the debugger. + +These encodings were defined at a time when the debugging information +format used was not powerful enough to describe some of the more complex +types available in Ada. Since DWARF allows us to express nearly all +Ada features, the long-term goal is to slowly replace these descriptive +types by their pure DWARF equivalent. To facilitate that transition, +a new maintenance option is available to force the debugger to ignore +those descriptive types. It allows the user to quickly evaluate how +well @value{GDBN} works without them. + +@table @code + +@kindex maint ada set ignore-descriptive-types +@item maintenance ada set ignore-descriptive-types [on|off] +Control whether the debugger should ignore descriptive types. +The default is to use descriptives types (@code{off}). + +@kindex maint ada show ignore-descriptive-types +@item maintenance ada show ignore-descriptive-types +Show if descriptive types are ignored by @value{GDBN}. + +@end table + + + @node Unsupported Languages @section Unsupported Languages -- 1.8.3.2