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Re: [RFA 4/4 doc] Explicit locations
- From: Keith Seitz <keiths at redhat dot com>
- To: "gdb-patches at sourceware dot org ml" <gdb-patches at sourceware dot org>
- Date: Thu, 21 Mar 2013 17:06:39 -0700
- Subject: Re: [RFA 4/4 doc] Explicit locations
- References: <514B9EC2 dot 5060502 at redhat dot com>
On 03/21/2013 04:58 PM, Keith Seitz wrote:
Anyway, let the fun begin.
Whoops. My apologies -- I didn't actually mean to send that out as an
attachment!
Keith
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index b885708..16ddadc 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -15975,10 +15975,9 @@ command" [PROBE_MODIFIER] [LOCATION] [thread
THREADNUM] [if CONDITION]\n\
PROBE_MODIFIER shall be present if the command is to be placed in a\n\
probe point. Accepted values are `-probe' (for a generic,
automatically\n\
guessed probe type) or `-probe-stap' (for a SystemTap probe).\n\
-LOCATION may be a line number, function name, or \"*\" and an address.\n\
-If a line number is specified, break at start of code for that line.\n\
-If a function is specified, break at start of code for that function.\n\
-If an address is specified, break at that exact address.\n\
+LOCATION may be a linespec, explicit, or address location. See \"help\n\
+locations\" for more help with specifying locations.\n\
+\n\
With no LOCATION, uses current execution address of the selected\n\
stack frame. This is useful for breaking on return to a stack frame.\n\
\n\
@@ -16511,11 +16510,9 @@ This command may be abbreviated \"delete\"."),
&deletelist);
add_com ("clear", class_breakpoint, clear_command, _("\
-Clear breakpoint at specified line or function.\n\
-Argument may be line number, function name, or \"*\" and an address.\n\
-If line number is specified, all breakpoints in that line are cleared.\n\
-If function is specified, breakpoints at beginning of function are
cleared.\n\
-If an address is specified, breakpoints at that address are cleared.\n\
+Clear breakpoint at specified location.\n\
+Argument may be a linespec, explicit, or address location. Seen\n\
+\"help locations\" for more help with specifying locations.\n\
\n\
With no argument, clears all breakpoints in the line that the selected
frame\n\
is executing in.\n\
@@ -16752,12 +16749,10 @@ Do \"help tracepoints\" for info on other
tracepoint commands."));
Set a static tracepoint at specified line, function or marker.\n\
\n\
strace [LOCATION] [if CONDITION]\n\
-LOCATION may be a line number, function name, \"*\" and an address,\n\
-or -m MARKER_ID.\n\
-If a line number is specified, probe the marker at start of code\n\
-for that line. If a function is specified, probe the marker at start\n\
-of code for that function. If an address is specified, probe the marker\n\
-at that exact address. If a marker id is specified, probe the marker\n\
+LOCATION may be a linespec, explicit, or address location or\n\
+or -m MARKER_ID. See \"help locations\" for more help with specifying\n\
+locations.\n\
+If a marker id is specified, probe the marker\n\
with that name. With no LOCATION, uses current execution address of\n\
the selected stack frame.\n\
Static tracepoints accept an extra collect action -- ``collect
$_sdata''.\n\
@@ -16921,12 +16916,10 @@ an instruction at any address within the
[START-LOCATION, END-LOCATION]\n\
range (including START-LOCATION and END-LOCATION)."));
c = add_com ("dprintf", class_breakpoint, dprintf_command, _("\
-Set a dynamic printf at specified line or function.\n\
+Set a dynamic printf at specified location.\n\
dprintf location,format string,arg1,arg2,...\n\
-location may be a line number, function name, or \"*\" and an address.\n\
-If a line number is specified, break at start of code for that line.\n\
-If a function is specified, break at start of code for that function.\n\
-"));
+location may be a linespec, explicit, or address location. See \"help\n\
+locations\" for more help with specifying locations."));
set_cmd_completer (c, location_completer);
add_setshow_enum_cmd ("dprintf-style", class_support,
@@ -16975,4 +16968,108 @@ agent-printf \"printf format string\", arg1,
arg2, arg3, ..., argn\n\
automatic_hardware_breakpoints = 1;
observer_attach_about_to_proceed (breakpoint_about_to_proceed);
+
+ add_com ("locations", help_class, NULL,
+ _("GDB supports several ways to specify locations. Any place\n\
+a location is required, any of the following forms is permissible.\n\
+\n\
+ A LINESPEC is a colon-separated list of source location parameters\n\
+ such as file name, function name, etc. Acceptable forms of linespecs\n\
+ include:\n\
+\n\
+ LINENUM\n\
+ Specifies the line number LINENUM of the current source file.\n\
+\n\
+ -OFFSET\n\
+ +OFFSET\n\
+ Specifies the line OFFSET lines before or after the current line.\n\
+\n\
+ FILE:LINENUM\n\
+ Specifies the line LINENUM in the source file FILE. If FILE\n\
+ is a relative file name, then it will match any source file name\n\
+ with the same trailing components.\n\
+\n\
+ FUNCTION\n\
+ Specifies the line that begins the body of the function FUNCTION.\n\
+ For example, in C, this is the line with the open brace.\n\
+\n\
+ FUNCTION:LABEL\n\
+ Specifies the line where LABEL appears in FUNCTION.\n\
+\n\
+ FILE:FUNCTION\n\
+ Specifies the line that begins the body of the function FUNCTION\n\
+ in the file FILE. You only need the file name with a function\n\
+ name to avoid ambiguity when there are identically named functions\n\
+ in different source files.\n\
+\n\
+ LABEL\n\
+ Specifies the line at which the label named LABEL appears in the\n\
+ function corresponding to the current stack frame. If there is\n\
+ no current selected frame (for instance, if the inferior is not\n\
+ running), then GDB will not search for a label.\n\
+\n\
+ EXPLICIT LOCATIONS bypass the linespec parser, allowing the user to\n\
+ explicitly specify the source location's parameters. They are
specified\n\
+ using option-value pairs listed in the table below.\n\
+\n\
+ Parsing linespecs often involves multiple searches through the
program's\n\
+ symbol table or the file system. For large programs, this may be\n\
+ extremely time-consuming. Explicit locations may help avoid a lot of\n\
+ this unnecessary searching.\n\
+\n\
+ The list of valid explicit location options is summarized in the\n\
+ following table:\n\
+\n\
+ -source\n\
+ The value specifies the source file name. This option\n\
+ requires the use of either -function or -line.\n\
+\n\
+ -function\n\
+ The value specifies the name of a function. Operations\n\
+ on function locations unmodified by other options (such as\n\
+ -label or -line) affect the line that begins the body of the\n\
+ function. In C, for example, this is the line with the open
brace.\n\
+\n\
+ -label\n\
+ The value specifies a line offset for that location. The offset\n\
+ may either be absolute (-line 3) or relative (-line +3), depending\n\
+ on the command. When specified without any other options, the\n\
+ line offset is relative to the current function.\n\
+\n\
+ Explicit location options may be abbreviated by omitting any
non-unique\n\
+ trailing characters from the option name, e.g.,\n\
+ \"break -s main.c -li 3\".\n\
+\n\
+ ADDRESS LOCATIONS indicate a specific program address. They have the\n\
+ generalized form *ADDRESS.\n\
+\n\
+ For line-oriented commands, such as list and edit, this specifies\n\
+ a source line that contains ADDRESS. For break and other breakpoint-\n\
+ oriented commands, this can be used to set breakpoints in parts of\n\
+ your program which do not have debugging information or source files.\n\
+\n\
+ ADDRESS may be any expression valid in the current working language\n\
+ that specifies a code address. In addition, as a convenience, GDB\n\
+ extends the semantics of expressions used in locations to cover
several\n\
+ situations that frequently occur during debugging. Here are the
various\n\
+ forms of ADDRESS:\n\
+\n\
+ EXPRESSION\n\
+ Any expression valid in the current working language.\n\
+\n\
+ FUNCADDR\n\
+ An address of a function or procedure derived from its name. In C,\n\
+ C++, Java, Objective-C, Fortran, minimal, and assembly, this is\n\
+ simply the function's name FUNCTION (and actually a special case
of\n\
+ a valid expression). In Ada, this is FUNCTION'Address (although\n\
+ the Pascal form also works).\n\
+\n\
+ This form specifies the address of the function's first
instruction,\n\
+ before the stack frame and arguments have been set up.\n\
+\n\
+ 'FILE'::FUNCADDR\n\
+ Like FUNCADDR above, but also specifies the name of the source\n\
+ file explicitly. This is useful if the name of the function does\n\
+ not specify the function unambiguously, e.g., if there are several\n\
+ functions with identical names in different source files."));
}
diff --git a/gdb/cli/cli-decode.c b/gdb/cli/cli-decode.c
index 61a7b5a..95b55c1 100644
--- a/gdb/cli/cli-decode.c
+++ b/gdb/cli/cli-decode.c
@@ -948,7 +948,8 @@ help_cmd (char *arg, struct ui_file *stream)
fputs_filtered (c->doc, stream);
fputs_filtered ("\n", stream);
- if (c->prefixlist == 0 && c->func != NULL)
+ if ((c->prefixlist == 0 && c->func != NULL)
+ || c->class == help_class)
return;
fprintf_filtered (stream, "\n");
@@ -1161,7 +1162,8 @@ help_cmd_list (struct cmd_list_element *list, enum
command_class class,
for (c = list; c; c = c->next)
{
- if (c->abbrev_flag == 0
+ if (c->class != help_class
+ && c->abbrev_flag == 0
&& (class == all_commands
|| (class == all_classes && c->func == NULL)
|| (class == c->class && c->func != NULL)))
diff --git a/gdb/command.h b/gdb/command.h
index 81edc43..777e847 100644
--- a/gdb/command.h
+++ b/gdb/command.h
@@ -33,7 +33,8 @@
enum command_class
{
/* Special args to help_list */
- class_deprecated = -3, all_classes = -2, all_commands = -1,
+ class_deprecated = -4, help_class = -3, all_classes = -2,
+ all_commands = -1,
/* Classes of commands */
no_class = -1, class_run = 0, class_vars, class_stack, class_files,
class_support, class_info, class_breakpoint, class_trace,
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 4ac28bb..0c2e04a 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -5784,9 +5784,9 @@ breakpoints on all threads, or on a particular thread.
@cindex breakpoints and threads
@cindex thread breakpoints
@kindex break @dots{} thread @var{threadno}
-@item break @var{linespec} thread @var{threadno}
-@itemx break @var{linespec} thread @var{threadno} if @dots{}
-@var{linespec} specifies source lines; there are several ways of
+@item break @var{location} thread @var{threadno}
+@itemx break @var{location} thread @var{threadno} if @dots{}
+@var{location} specifies source lines; there are several ways of
writing them (@pxref{Specify Location}), but the effect is always to
specify some source line.
@@ -6931,21 +6931,21 @@ argument of @samp{-}; that argument is preserved
in repetition so that
each repetition moves up in the source file.
In general, the @code{list} command expects you to supply zero, one or two
-@dfn{linespecs}. Linespecs specify source lines; there are several ways
+@dfn{locations}. Locations specify source lines; there are several ways
of writing them (@pxref{Specify Location}), but the effect is always
to specify some source line.
Here is a complete description of the possible arguments for @code{list}:
@table @code
-@item list @var{linespec}
-Print lines centered around the line specified by @var{linespec}.
+@item list @var{location}
+Print lines centered around the line specified by @var{location}.
@item list @var{first},@var{last}
Print lines from @var{first} to @var{last}. Both arguments are
-linespecs. When a @code{list} command has two linespecs, and the
-source file of the second linespec is omitted, this refers to
-the same source file as the first linespec.
+locations. When a @code{list} command has two locations, and the
+source file of the second location is omitted, this refers to
+the same source file as the first location.
@item list ,@var{last}
Print lines ending with @var{last}.
@@ -6970,15 +6970,21 @@ As described in the preceding table.
Several @value{GDBN} commands accept arguments that specify a location
of your program's code. Since @value{GDBN} is a source-level
-debugger, a location usually specifies some line in the source code;
-for that reason, locations are also known as @dfn{linespecs}.
+debugger, a location usually specifies some line in the source code.
+Locations may be specified using three different formats,
+linespec locations, explicit locations, or address locations.
-Here are all the different ways of specifying a code location that
-@value{GDBN} understands:
+@node Linespec Locations
+@subsection Linespec Locations
+
+A @dfn{linespec} is a colon-separated list of source location
parameters such
+as file name, function name, etc. They are parsed and converted into an
+internal representation used by @value{GDBN}. Here are all the
+different ways of specifying a linespec:
@table @code
@item @var{linenum}
-Specifies the line number @var{linenum} of the current source file.
+Specifies the line number @var{linenum} of the @dfn{current source} file.
@item -@var{offset}
@itemx +@var{offset}
@@ -7013,25 +7019,90 @@ function name to avoid ambiguity when there are
identically named
functions in different source files.
@item @var{label}
-Specifies the line at which the label named @var{label} appears.
-@value{GDBN} searches for the label in the function corresponding to
-the currently selected stack frame. If there is no current selected
-stack frame (for instance, if the inferior is not running), then
-@value{GDBN} will not search for a label.
-
-@item *@var{address}
-Specifies the program address @var{address}. For line-oriented
-commands, such as @code{list} and @code{edit}, this specifies a source
-line that contains @var{address}. For @code{break} and other
-breakpoint oriented commands, this can be used to set breakpoints in
+Specifies the line at which the label named @var{label} appears
+in the function corresponding to the currently selected stack frame.
+If there is no current selected stack frame (for instance, if the inferior
+is not running), then @value{GDBN} will not search for a label.
+
+@cindex breakpoint at static probe point
+@item -pstap|-probe-stap
@r{[}@var{objfile}:@r{[}@var{provider}:@r{]}@r{]}@var{name}
+The @sc{gnu}/Linux tool @code{SystemTap} provides a way for
+applications to embed static probes. @xref{Static Probe Points}, for more
+information on finding and using static probes. This form of linespec
+specifies the location of such a static probe.
+
+If @var{objfile} is given, only probes coming from that shared library
+or executable matching @var{objfile} as a regular expression are
considered.
+If @var{provider} is given, then only probes from that provider are
considered.
+If several probes match the spec, @value{GDBN} will insert a breakpoint at
+each one of those probes.
+@end table
+
+@node Explicit Locations
+@subsection Explicit Locations
+@cindex explicit locations
+
+@dfn{Explict locations} bypass the linespec parser, allowing the user
+to explicitly specify the source location's parameters. They are specified
+using option-value pairs listed in the table below.
+
+Parsing linespecs often involves multiple searches through the program's
+symbol table or the file system. For large programs, this may be extremely
+time-consuming. Explicit locations may help avoid a lot of this
+unnecessary searching.
+
+For example, the linespec ``foo:bar'' may refer to a function ``bar''
+defined in the file named ``foo'' or the label ``bar'' in a function
+named ``foo''. @value{GDBN} must search either the file system or
+the symbol table to know.
+
+The list of valid explicit location options is summarized in the
+following table:
+
+@table @code
+@item -source
+The value specifies the source file name. This option
+requires the use of either @code{-function} or @code{-line}.
+
+@item -function
+The value specifies the name of a function. Operations
+on function locations unmodified by other options (such as @code{-label}
+or @code{-line}) affect the line that begins the body of the function.
+In C, for example, this is the line with the open brace.
+
+@item -label
+The value specifies the name of a label. When the function
+name is not specified, the label is searched in the function of the
currently
+selected stack frame.
+
+@item -line
+The value specifies a line offset for the location. The offset may either
+be absolute (@code{-line 3}) or relative (@code{-line +3}), depending on
+the command. When specified without any other options, the line offset is
+relative to the current function.
+@end table
+
+Explicit location options may be abbreviated by omitting any non-unique
+trailing characters from the option name, e.g., @code{break -s main.c
-li 3}.
+
+@node Address Locations
+@subsection Address Locations
+@cindex address locations
+
+@dfn{Address locations} indicate a specific program address. They have
+the generalized form *@var{address}.
+
+For line-oriented commands, such as @code{list} and @code{edit}, this
+specifies a source line that contains @var{address}. For @code{break} and
+other breakpoint-oriented commands, this can be used to set breakpoints in
parts of your program which do not have debugging information or
source files.
-Here @var{address} may be any expression valid in the current working
+@var{address} may be any expression valid in the current working
language (@pxref{Languages, working language}) that specifies a code
address. In addition, as a convenience, @value{GDBN} extends the
-semantics of expressions used in locations to cover the situations
-that frequently happen during debugging. Here are the various forms
+semantics of expressions used in locations to cover several situations
+that frequently occur during debugging. Here are the various forms
of @var{address}:
@table @code
@@ -7056,22 +7127,6 @@ specify the function unambiguously, e.g., if
there are several
functions with identical names in different source files.
@end table
-@cindex breakpoint at static probe point
-@item -pstap|-probe-stap
@r{[}@var{objfile}:@r{[}@var{provider}:@r{]}@r{]}@var{name}
-The @sc{gnu}/Linux tool @code{SystemTap} provides a way for
-applications to embed static probes. @xref{Static Probe Points}, for more
-information on finding and using static probes. This form of linespec
-specifies the location of such a static probe.
-
-If @var{objfile} is given, only probes coming from that shared library
-or executable matching @var{objfile} as a regular expression are
considered.
-If @var{provider} is given, then only probes from that provider are
considered.
-If several probes match the spec, @value{GDBN} will insert a breakpoint at
-each one of those probes.
-
-@end table
-
-
@node Edit
@section Editing Source Files
@cindex editing source files
@@ -7389,9 +7444,9 @@ well as hex.
@table @code
@kindex info line
-@item info line @var{linespec}
+@item info line @var{location}
Print the starting and ending addresses of the compiled code for
-source line @var{linespec}. You can specify source lines in any of
+source line @var{location}. You can specify source lines in any of
the ways documented in @ref{Specify Location}.
@end table
@@ -7409,7 +7464,7 @@ Line 895 of "builtin.c" starts at pc 0x634c and
ends at 0x6350.
@noindent
@cindex code address and its source line
We can also inquire (using @code{*@var{addr}} as the form for
-@var{linespec}) what source line covers a particular address:
+@var{location}) what source line covers a particular address:
@smallexample
(@value{GDBP}) info line *0x63ff
Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404.
@@ -7519,7 +7574,7 @@ Dump of assembler code from 0x400281 to 0x40028b:
End of assembler dump.
@end smallexample
-Addresses cannot be specified as a linespec (@pxref{Specify Location}).
+Addresses cannot be specified as a location (@pxref{Specify Location}).
So, for example, if you want to disassemble function @code{bar}
in file @file{foo.c}, you must type @samp{disassemble 'foo.c'::bar}
and not @samp{disassemble foo.c:bar}.
@@ -10848,9 +10903,9 @@ argument processing and the beginning of
@var{macro} for non C-like macros where
the macro may begin with a hyphen.
@kindex info macros
-@item info macros @var{linespec}
+@item info macros @var{location}
Show all macro definitions that are in effect at the location specified
-by @var{linespec}, and describe the source location or compiler
+by @var{location}, and describe the source location or compiler
command-line where those definitions were established.
@kindex macro define
@@ -14973,14 +15028,14 @@ from the current task to the given task.
#4 0x804aacc in un () at un.adb:5
@end smallexample
-@item break @var{linespec} task @var{taskno}
-@itemx break @var{linespec} task @var{taskno} if @dots{}
+@item break @var{location} task @var{taskno}
+@itemx break @var{location} task @var{taskno} if @dots{}
@cindex breakpoints and tasks, in Ada
@cindex task breakpoints, in Ada
@kindex break @dots{} task @var{taskno}@r{ (Ada)}
These commands are like the @code{break @dots{} thread @dots{}}
command (@pxref{Thread Stops}).
-@var{linespec} specifies source lines, as described
+@var{location} specifies source lines, as described
in @ref{Specify Location}.
Use the qualifier @samp{task @var{taskno}} with a breakpoint command
@@ -15806,20 +15861,17 @@ an address of your own choosing, with the
following commands:
@table @code
@kindex jump
@kindex j @r{(@code{jump})}
-@item jump @var{linespec}
-@itemx j @var{linespec}
-@itemx jump @var{location}
+@item jump @var{location}
@itemx j @var{location}
-Resume execution at line @var{linespec} or at address given by
-@var{location}. Execution stops again immediately if there is a
-breakpoint there. @xref{Specify Location}, for a description of the
-different forms of @var{linespec} and @var{location}. It is common
+Resume execution at @var{location}. Execution stops again immediately
+if there is a breakpoint there. @xref{Specify Location}, for a description
+of the different forms of @var{location}. It is common
practice to use the @code{tbreak} command in conjunction with
@code{jump}. @xref{Set Breaks, ,Setting Breakpoints}.
The @code{jump} command does not change the current stack frame, or
the stack pointer, or the contents of any memory location or any
-register other than the program counter. If line @var{linespec} is in
+register other than the program counter. If @var{location} is in
a different function from the one currently executing, the results may
be bizarre if the two functions expect different patterns of arguments or
of local variables. For this reason, the @code{jump} command requests
@@ -28784,22 +28836,42 @@ N.A.
@smallexample
-break-insert [ -t ] [ -h ] [ -f ] [ -d ] [ -a ]
[ -c @var{condition} ] [ -i @var{ignore-count} ]
- [ -p @var{thread-id} ] [ @var{location} ]
+ [ -p @var{thread-id} ] @var{location}
+
@end smallexample
@noindent
If specified, @var{location}, can be one of:
-@itemize @bullet
-@item function
-@c @item +offset
-@c @item -offset
-@c @item linenum
-@item filename:linenum
-@item filename:function
-@item *address
-@end itemize
+@table @var
+@item linespec location
+A linespec location. @xref{Linespec Locations}.
+
+@item explicit location
+An explicit location. @sc{gdb/mi} explicit locations are
+analogous to @value{GDBN}'s explicit locations using the option names
+listed below. @xref{Explicit Locations}.
+
+@table @samp
+@item -s @var{filename}
+The source file name of the location. This option requires the use
+of either @samp{-m} or @samp{-o}.
+@item -m @var{function}
+The name of a function or method.
+
+@item -l @var{label}
+The name of a label.
+
+@item -o @var{lineoffset}
+An absolute or relative offset from the start of the location.
+@end table
+
+@item address location
+An address location, *@var{address}. @xref{Address Locations}.
+@end table
+
+@noindent
The possible optional parameters of this command are:
@table @samp
diff --git a/gdb/testsuite/gdb.base/help.exp
b/gdb/testsuite/gdb.base/help.exp
index 86a02eb..095c97a 100644
--- a/gdb/testsuite/gdb.base/help.exp
+++ b/gdb/testsuite/gdb.base/help.exp
@@ -125,3 +125,6 @@ gdb_test "apropos \\\(print\[\^ bsiedf\\\".-\]\\\)"
"handle -- Specify how to ha
gdb_test "apropos handle signal" "handle -- Specify how to handle signals"
# test apropos apropos
gdb_test "apropos apropos" "apropos -- Search for commands matching a
REGEXP"
+
+# Test help class commands
+gdb_test "help locations" "GDB supports several.*"