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Re: [RFA 5/9] Explicit locations v2 - Add probe locations
- From: Doug Evans <dje at google dot com>
- To: Keith Seitz <keiths at redhat dot com>
- Cc: "gdb-patches at sourceware dot org ml" <gdb-patches at sourceware dot org>
- Date: Sat, 2 Aug 2014 16:38:58 -0700
- Subject: Re: [RFA 5/9] Explicit locations v2 - Add probe locations
- Authentication-results: sourceware.org; auth=none
- References: <536BC69E dot 9060008 at redhat dot com> <5388CB91 dot 4030802 at redhat dot com>
Hi. Comments inline, mostly nits.
Keith Seitz writes:
> This is also an update of this patch based on feedback from previous
> patch reviews.
>
> Keith
>
> Changes since last revision:
> - use make_cleanup_delete_event_location
> - remove SAVE_SPEC
> - new_probe_location
>
> ChangeLog
> 2014-05-29 Keith Seitz <keiths@redhat.com>
>
> * break-catch-throw.c (re_set_exception_catchpoint): Convert
> linespec for stap probe to probe location.
> * breakpoint.c (create_longjmp_master_breakpoint): Likewise.
> (create_exception_master_breakpoint): Likewise.
> (break_command_1): Remove local variable `arg_cp'.
> Check location type to set appropriate breakpoint ops methods.
> (trace_command): Likewise.
> * linespec.c (event_location_to_sals): Handle probe locations.
> * location.c (copy_event_location): Likewise.
> (delete_event_location): Likewise.
> (event_location_to_string): Likewise.
> (string_to_event_location): Likewise.
> (event_location_empty_p): Handel probe locations.
"Handle ...", or just "Likewise."
> * location.h (enum event_location_type): Add PROBE_LOCATION.
> (EVENT_LOCATION_PROBE): Define accessor macro.
> * probe.c (parse_probes): Assert that LOCATION is a probe location.
> Convert linespec into probe location.
>
>
>
> diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
> index e2c8365..207e7af 100644
> --- a/gdb/break-catch-throw.c
> +++ b/gdb/break-catch-throw.c
> @@ -214,8 +214,8 @@ re_set_exception_catchpoint (struct breakpoint *self)
> {
> struct event_location location;
>
> - initialize_event_location (&location, LINESPEC_LOCATION);
> - EVENT_LOCATION_LINESPEC (&location)
> + initialize_event_location (&location, PROBE_LOCATION);
> + EVENT_LOCATION_PROBE (&location)
> = ASTRDUP (exception_functions[kind].probe);
> sals = parse_probes (&location, NULL);
> }
> diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
> index ef60f44..345b104 100644
> --- a/gdb/breakpoint.c
> +++ b/gdb/breakpoint.c
> @@ -3387,7 +3387,7 @@ create_longjmp_master_breakpoint (void)
> bp_longjmp_master,
> &internal_breakpoint_ops);
> b->location
> - = new_linespec_location ("-probe-stap libc:longjmp");
> + = new_probe_location ("-probe-stap libc:longjmp");
> b->enable_state = bp_disabled;
> }
>
> @@ -3551,7 +3551,7 @@ create_exception_master_breakpoint (void)
> bp_exception_master,
> &internal_breakpoint_ops);
> b->location
> - = new_linespec_location ("-probe-stap libgcc:unwind");
> + = new_probe_location ("-probe-stap libgcc:unwind");
> b->enable_state = bp_disabled;
> }
>
> @@ -10068,7 +10068,6 @@ break_command_1 (char *arg, int flag, int from_tty)
> ? bp_hardware_breakpoint
> : bp_breakpoint);
> struct breakpoint_ops *ops;
> - const char *arg_cp = arg;
> struct event_location *location;
> struct cleanup *cleanup;
>
> @@ -10076,7 +10075,8 @@ break_command_1 (char *arg, int flag, int from_tty)
> cleanup = make_cleanup_delete_event_location (location);
>
> /* Matching breakpoints on probes. */
> - if (arg_cp != NULL && probe_linespec_to_ops (&arg_cp) != NULL)
> + if (location != NULL
> + && EVENT_LOCATION_TYPE (location) == PROBE_LOCATION)
> ops = &bkpt_probe_breakpoint_ops;
> else
> ops = &bkpt_breakpoint_ops;
> @@ -15432,11 +15432,11 @@ trace_command (char *arg, int from_tty)
> struct breakpoint_ops *ops;
> struct event_location *location;
> struct cleanup *back_to;
> - const char *arg_cp = arg;
>
> location = string_to_event_location (&arg, current_language);
> back_to = make_cleanup_delete_event_location (location);
> - if (arg_cp != NULL && probe_linespec_to_ops (&arg_cp) != NULL)
> + if (location != NULL
> + && EVENT_LOCATION_TYPE (location) == PROBE_LOCATION)
> ops = &tracepoint_probe_breakpoint_ops;
> else
> ops = &tracepoint_breakpoint_ops;
> diff --git a/gdb/linespec.c b/gdb/linespec.c
> index 8ea0c7b..deda86e 100644
> --- a/gdb/linespec.c
> +++ b/gdb/linespec.c
> @@ -2433,6 +2433,11 @@ event_location_to_sals (linespec_parser *parser,
> EVENT_LOCATION_ADDRESS (location));
> break;
>
> + case PROBE_LOCATION:
> + /* Probes are handled by their own decoders. */
> + gdb_assert_not_reached ("attempt to decode probe location");
extra space of indentation
> + break;
> +
> default:
> gdb_assert_not_reached ("unhandled event location type");
> }
> diff --git a/gdb/location.c b/gdb/location.c
> index 3c430db..eafa27d 100644
> --- a/gdb/location.c
> +++ b/gdb/location.c
> @@ -67,6 +67,21 @@ new_address_location (CORE_ADDR addr)
> return location;
> }
>
> +/* Create a new probe location. The return result is malloc'd
> + and should be freed with delete_event_location. */
> +
> +struct event_location *
> +new_probe_location (const char *probe)
> +{
> + struct event_location *location;
> +
> + location = XNEW (struct event_location);
> + initialize_event_location (location, PROBE_LOCATION);
> + if (probe != NULL)
> + EVENT_LOCATION_PROBE (location) = xstrdup (probe);
> + return location;
> +}
> +
> /* Return a copy of the given SRC location. */
>
> struct event_location *
> @@ -89,6 +104,10 @@ copy_event_location (const struct event_location *src)
> EVENT_LOCATION_ADDRESS (dst) = EVENT_LOCATION_ADDRESS (src);
> break;
>
> + case PROBE_LOCATION:
> + EVENT_LOCATION_PROBE (dst) = xstrdup (EVENT_LOCATION_PROBE (src));
> + break;
> +
> default:
> gdb_assert_not_reached ("unknown event location type");
> }
> @@ -133,6 +152,10 @@ delete_event_location (struct event_location *location)
> /* Nothing to do. */
> break;
>
> + case PROBE_LOCATION:
> + xfree (EVENT_LOCATION_PROBE (location));
> + break;
> +
> default:
> gdb_assert_not_reached ("unknown event location type");
> }
> @@ -166,6 +189,10 @@ event_location_to_string_const (const struct event_location *location)
> core_addr_to_string (EVENT_LOCATION_ADDRESS (location)));
> break;
>
> + case PROBE_LOCATION:
> + result = xstrdup (EVENT_LOCATION_PROBE (location));
> + break;
> +
> default:
> gdb_assert_not_reached ("unknown event location type");
> }
> @@ -212,10 +239,23 @@ string_to_event_location (char **stringp,
> }
> else
> {
> - /* Everything else is a linespec. */
> - location = new_linespec_location (*stringp);
> - if (*stringp != NULL)
> - *stringp += strlen (*stringp);
> + const char *cs;
> +
> + /* Next, try the input as a probe spec. */
> + cs = *stringp;
> + if (cs != NULL && probe_linespec_to_ops (&cs) != NULL)
> + {
> + location = new_probe_location (*stringp);
> + if (*stringp != NULL)
This test is unnecessary (right?).
btw, when will this function be passed *stringp == NULL?
Can this function have an "early exit" if *stringp == NULL?
[assuming that makes sense]
> + *stringp += strlen (*stringp);
> + }
> + else
> + {
> + /* Everything else is a linespec. */
> + location = new_linespec_location (*stringp);
> + if (*stringp != NULL)
> + *stringp += strlen (*stringp);
> + }
> }
>
> return location;
> @@ -234,6 +274,9 @@ event_location_empty_p (const struct event_location *location)
> case ADDRESS_LOCATION:
> return 0;
>
> + case PROBE_LOCATION:
> + return EVENT_LOCATION_PROBE (location) == NULL;
> +
> default:
> gdb_assert_not_reached ("unknown event location type");
> }
> diff --git a/gdb/location.h b/gdb/location.h
> index 1daefb6..e6f14d9 100644
> --- a/gdb/location.h
> +++ b/gdb/location.h
> @@ -30,7 +30,10 @@ enum event_location_type
> LINESPEC_LOCATION,
>
> /* An address in the inferior. */
> - ADDRESS_LOCATION
> + ADDRESS_LOCATION,
> +
> + /* A probe location. */
> + PROBE_LOCATION
> };
>
> /* An event location used to set a stop event in the inferior.
> @@ -50,6 +53,7 @@ struct event_location
> probes. */
> char *addr_string;
> #define EVENT_LOCATION_LINESPEC(S) ((S)->u.addr_string)
> +#define EVENT_LOCATION_PROBE(S) ((S)->u.addr_string)
>
> /* An address in the inferior. */
> CORE_ADDR address;
> @@ -98,6 +102,12 @@ extern struct event_location *
> extern struct event_location *
> new_address_location (CORE_ADDR addr);
>
> +/* Create a new probe location. The return result is malloc'd
> + and should be freed with delete_event_location. */
> +
> +extern struct event_location *
> + new_probe_location (const char *probe);
> +
> /* Return a copy of the given SRC location. */
>
> extern struct event_location *
> diff --git a/gdb/probe.c b/gdb/probe.c
> index c7597d9..2ff5d86 100644
> --- a/gdb/probe.c
> +++ b/gdb/probe.c
> @@ -58,7 +58,8 @@ parse_probes (struct event_location *location,
> result.sals = NULL;
> result.nelts = 0;
>
> - arg_start = EVENT_LOCATION_LINESPEC (location);
> + gdb_assert (EVENT_LOCATION_TYPE (location) == PROBE_LOCATION);
> + arg_start = EVENT_LOCATION_PROBE (location);
>
> cs = arg_start;
> probe_ops = probe_linespec_to_ops (&cs);
> @@ -173,12 +174,12 @@ parse_probes (struct event_location *location,
> {
> canonical->special_display = 1;
> canonical->pre_expanded = 1;
> - canonical->location = new_linespec_location (NULL);
> - EVENT_LOCATION_LINESPEC (canonical->location)
> + canonical->location = new_probe_location (NULL);
> + EVENT_LOCATION_PROBE (canonical->location)
> = savestring (arg_start, arg_end - arg_start);
I see why you pass NULL to new_probe_location and then set EVENT_LOCATION_PROBE
afterwards (otherwise two copies of the string would be malloc'd, and you'd
need to deal with freeing one of them). One could add a version of
new_probe_location that took a char* and a length, but that seems excessive.
Another place where c++ would allow cleaner code.
> }
>
> - EVENT_LOCATION_LINESPEC (location) = arg_end;
> + EVENT_LOCATION_PROBE (location) = arg_end;
> do_cleanups (cleanup);
The function starts out with:
arg_start = EVENT_LOCATION_PROBE (location);
and at the end we do this:
EVENT_LOCATION_PROBE (location) = arg_end;
IWBN to document why we do this, it's not obvious to me why that is.
[doesn't have to be part of this patch set though]
>
> return result;