[RFC] Python Finish Breakpoints

[Kevin Pouget]

On Fri, Dec 2, 2011 at 10:48 PM, Tom Tromey <tromey@redhat.com> wrote:
>
> >>>>> "Kevin" == Kevin Pouget <kevin.pouget@gmail.com> writes:
>
> Sorry about the delay on this.
> I got kind of distracted this week.
>
> Kevin> I noticed a bug in the previous version of the patch, which led to
> Kevin> `out_of_scope' callback being triggered when it was not supposed to be
> Kevin> (namely, when the breakpoint was hit, the execution continued, and
> Kevin> then the callback was triggered before the temporary breakpoint could
> Kevin> be deleted.
>
> Looking close now.
>
> Kevin> +      if (ret)
> Kevin> +        self_finishbp->return_value = value_to_value_object (ret);
>
> If this fails then the error is never cleared or handled.
>
> I think checking == NULL and then calling gdbpy_print_stack is appropriate.

you're right, fixed

>
> Kevin> +                  /* Ignore Python errors at this stage.  */
> Kevin> +                  self_bpfinish->return_type = type_to_type_object (ret_type);
> Kevin> +                  PyErr_Clear ();
> Kevin> +                  self_bpfinish->function_type =
> Kevin> +                      type_to_type_object (SYMBOL_TYPE (function));
> Kevin> +                  PyErr_Clear ();
>
> This looked a little weird, but I verified from the docs that it is ok.
>
> I think this still needs a NEWS entry.

nop, it was in the patch :)

diff --git a/gdb/NEWS b/gdb/NEWS
index f13caf8..7b3f7f2 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -51,6 +51,10 @@
   ** The "gdb.breakpoint" function has been deprecated in favor of
      "gdb.breakpoints".

+  ** A new class "gdb.FinishBreakpoint" is provided to catch the return
+     of a function.  This class is based on the "finish" command
+     available in the CLI.
+
   ** Type objects for struct and union types now allow access to
      the fields using standard Python dictionary (mapping) methods.
      For example, "some_type['myfield']" now works, as does

it was also reviewed by Eli in :
http://sourceware.org/ml/gdb-patches/2011-10/msg00645.html


Thanks for your review,

cordially,

Kevin

(no regression against current git source tree)

--

2011-12-05  Kevin Pouget  <kevin.pouget@st.com>

	Introduce gdb.FinishBreakpoint in Python

	* Makefile.in (SUBDIR_PYTHON_OBS): Add py-finishbreakpoint.o.
	(SUBDIR_PYTHON_SRCS): Add python/py-finishbreakpoint.c.
	Add build rule for this file.
	* infcmd.c (print_return_value): Split to create get_return_value.
	(get_return_value): New function based on print_return_value. Handle
	case where stop_registers are not set.
	* inferior.h (get_return_value): New prototype.
	* python/py-breakpoint.c (bppy_pending_object): Make non-static.
	(gdbpy_breakpoint_created): Set is_py_finish_bp is necessary.
	(struct breakpoint_object): Move to python-internal.h
	(BPPY_REQUIRE_VALID): Likewise.
	(BPPY_SET_REQUIRE_VALID): Likewise.
	(gdbpy_breakpoint_created): Initialize is_finish_bp.
	(gdbpy_should_stop): Add  pre/post hooks before/after calling stop
	method.
	* python/python-internal.h (breakpoint_object_type): Add as extern.
	(bppy_pending_object): Likewise.
	(typedef struct breakpoint_object) Removed.
	(struct breakpoint_object): Moved from py-breakpoint.c.
	Add field is_finish_bp.
	(BPPY_REQUIRE_VALID): Moved from py-breakpoint.c.
	(BPPY_SET_REQUIRE_VALID): Likewise.
	(frame_object_to_frame_info): New prototype.
	(gdbpy_initialize_finishbreakpoints): New prototype.
	(bpfinishpy_is_finish_bp): Likewise.
	(bpfinishpy_pre_stop_hook): Likewise.
	(bpfinishpy_post_stop_hook): Likewise.
	* python/py-finishbreakpoint.c: New file.
	* python/py-frame.c(frame_object_to_frame_info): Make non-static and
	accept PyObject instead of frame_object.
	(frapy_is_valid): Don't cast to frame_object.
	(frapy_name): Likewise.
	(frapy_type): Likewise.
	(frapy_unwind_stop_reason): Likewise.
	(frapy_pc): Likewise.
	(frapy_block): Likewise.
	(frapy_function): Likewise.
	(frapy_older): Likewise.
	(frapy_newer): Likewise.
	(frapy_find_sal): Likewise.
	(frapy_read_var): Likewise.
	(frapy_select): Likewise.
	* python/python.c (gdbpy_is_stopped_at_finish_bp): New noop function.
	(_initialize_python): Add gdbpy_initialize_finishbreakpoints.
	* python/python.h: Include breakpoint.h
	(gdbpy_is_stopped_at_finish_bp): New prototype.

doc/
	* gdb.texinfo (Finish Breakpoints in Python): New subsection.
	(Python API): Add menu entry for Finish Breakpoints.

testsuite/
	* gdb.python/py-breakpoint.exp (mult_line): Define and use variable
	instead of line number.
	* gdb.python/py-finish-breakpoint.c: New file.
	* gdb.python/py-finish-breakpoint.exp: New file.
	* gdb.python/py-finish-breakpoint.py: New file.
	* gdb.python/py-finish-breakpoint2.cc: New file.
	* gdb.python/py-finish-breakpoint2.exp: New file.
	* gdb.python/py-finish-breakpoint2.py: New file.
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