Re: [RFC - GDB Python API] New gdb.Architecture class

Siva Chandra
2013-01-23T13:53:14Z

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On Tue, Jan 22, 2013 at 1:17 PM, Tom Tromey <tromey@redhat.com> wrote:
>
> Siva> +typedef struct arch_object_type_object {
> Siva> + PyObject_HEAD
> Siva> + struct gdbarch *gdbarch;
> Siva> + struct arch_object_type_object *next;
> Siva> +} arch_object;
> Siva> +
> Siva> +static arch_object *arch_object_list = NULL;
>
> Instead of this I think you can associated the Python object with the
> gdbarch using gdbarch_data_register_post_init and gdbarch_data. This
> will let you attach the Python representation directly to the gdbarch.

Done in the attached patch.

2013-01-22 Siva Chandra Reddy <sivachandra@google.com>

Add a new class gdb.Architecture which exposes GDB's
internal representation of architecture via GDB Python API.

* Makefile.in: Add entries corresponding to the new file
python/py-arch.c.
* python/py-arch.c: Implement gdb.Architecture class.
* python/py-frame.c (frapy_arch): Implement the method
gdb.Frame.architecture().
(frame_object_methods): Add 'architecture' to the method table.
* python/python-internal.h: Add declarations of new utility
functions.
* python/python.c (_initialize_python): Initialize
gdb.Architecture class.

doc/

* gdb.texinfo (Architectures In Python): New sub-sub-section
describing the gdb.Architecture class.
(Frames In Python): Add description about the new method
Frame.architecture().

testsuite/

* gdb.python/frame.exp: Add a test for Frame.architecture()
method.

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diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 7305e6d..956963e 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -271,6 +271,7 @@ SUBDIR_TUI_CFLAGS= \
#
SUBDIR_PYTHON_OBS = \
python.o \
+ py-arch.o \
py-auto-load.o \
py-block.o \
py-bpevent.o \
@@ -304,6 +305,7 @@ SUBDIR_PYTHON_OBS = \

SUBDIR_PYTHON_SRCS = \
python/python.c \
+ python/py-arch.c \
python/py-auto-load.c \
python/py-block.c \
python/py-bpevent.c \
@@ -2045,6 +2047,10 @@ python.o: $(srcdir)/python/python.c
$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/python.c
$(POSTCOMPILE)

+py-arch.o: $(srcdir)/python/py-arch.c
+ $(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-arch.c
+ $(POSTCOMPILE)
+
py-auto-load.o: $(srcdir)/python/py-auto-load.c
$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-auto-load.c
$(POSTCOMPILE)
diff --git a/gdb/NEWS b/gdb/NEWS
index 49d8447..068e54c 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -39,6 +39,12 @@ Lynx 178 PowerPC powerpc-*-lynx*178

** Python 3 is now supported (in addition to Python 2.4 or later)

+ ** New class gdb.Architecture exposes GDB's internal representation
+ of architecture in the Python API.
+
+ ** New method Frame.architecture returns the gdb.Architecture object
+ corresponding to the frame's architecture.
+
* New Python-based convenience functions:

** $_memeq(buf1, buf2, length)
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 728e44b..9e6ae65 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -22807,6 +22807,7 @@ situation, a Python @code{KeyboardInterrupt} exception is thrown.
* Finish Breakpoints in Python:: Setting Breakpoints on function return
using Python.
* Lazy Strings In Python:: Python representation of lazy strings.
+* Architectures In Python:: Python representation of architectures.
@end menu

@node Basic Python
@@ -25110,6 +25111,11 @@ Returns the function name of the frame, or @code{None} if it can't be
obtained.
@end defun

+@defun Frame.architecture ()
+Returns the @code{gdb.Architecture} object corresponding to the frame's
+architecture. @xref{Architectures In Python}
+@end defun
+
@defun Frame.type ()
Returns the type of the frame. The value can be one of:
@table @code
@@ -25972,6 +25978,20 @@ resolve this to the lazy string's character type, use the type's
writable.
@end defvar

+@node Architectures In Python
+@subsubsection Python representation of architectures
+@cindex Python architectures
+
+@value{GDBN} uses architecture specific parameters and artifacts in a
+number of its various computations. An architecture is represented
+by an instance of the @code{gdb.Architecture} class.
+
+A @code{gdb.Architecture} class has the following methods:
+
+@defun Architecture.name ()
+Return the name (string value) of the architecture.
+@end defun
+
@node Python Auto-loading
@subsection Python Auto-loading
@cindex Python auto-loading
diff --git a/gdb/python/py-arch.c b/gdb/python/py-arch.c
new file mode 100644
index 0000000..edd508f
--- /dev/null
+++ b/gdb/python/py-arch.c
@@ -0,0 +1,149 @@
+/* Python interface to architecture
+
+ Copyright (C) 2013 Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#include "defs.h"
+#include "gdbarch.h"
+#include "arch-utils.h"
+#include "python-internal.h"
+
+typedef struct arch_object_type_object {
+ PyObject_HEAD
+ struct gdbarch *gdbarch;
+} arch_object;
+
+static struct gdbarch_data *arch_object_data = NULL;
+static PyTypeObject arch_object_type;
+
+/* Associates an arch_object with GDBARCH as gdbarch_data via the gdbarch
+ post init registration mechanism (gdbarch_data_register_post_init). */
+
+static void *
+arch_object_data_init (struct gdbarch *gdbarch)
+{
+ arch_object *arch_obj = PyObject_New (arch_object, &arch_object_type);
+
+ if (arch_obj == NULL)
+ return NULL;
+
+ arch_obj->gdbarch = gdbarch;
+
+ return (void *) arch_obj;
+}
+
+/* Returns the struct gdbarch value corresponding to the given Python
+ architecture object OBJ. */
+
+struct gdbarch *
+arch_object_to_gdbarch (PyObject *obj)
+{
+ arch_object *py_arch = (arch_object *) obj;
+
+ return py_arch->gdbarch;
+}
+
+/* Returns the Python architecture object corresponding to GDBARCH.
+ Returns a new reference to the arch_object associated as data with
+ GDBARCH. */
+
+PyObject *
+gdbarch_to_arch_object (struct gdbarch *gdbarch)
+{
+ PyObject *new_ref = (PyObject *) gdbarch_data (gdbarch, arch_object_data);
+
+ /* new_ref could be NULL if registration of arch_object with GDBARCH failed
+ in arch_object_data_init. */
+ Py_XINCREF (new_ref);
+
+ return new_ref;
+}
+
+/* Implementation of gdb.Architecture.name (self) -> String.
+ Returns the name of the architecture as a string value. */
+
+static PyObject *
+archpy_name (PyObject *self, PyObject *args)
+{
+ struct gdbarch *gdbarch = arch_object_to_gdbarch (self);
+ const char *name = (gdbarch_bfd_arch_info (gdbarch))->printable_name;
+ PyObject *py_name = PyString_FromString (name);
+
+ return py_name;
+}
+
+/* Initializes the Architecture class in the gdb module. */
+
+void
+gdbpy_initialize_arch (void)
+{
+ arch_object_data = gdbarch_data_register_post_init (arch_object_data_init);
+ arch_object_type.tp_new = PyType_GenericNew;
+ if (PyType_Ready (&arch_object_type) < 0)
+ return;
+
+ Py_INCREF (&arch_object_type);
+ PyModule_AddObject (gdb_module, "Architecture",
+ (PyObject *) &arch_object_type);
+}
+
+static PyMethodDef arch_object_methods [] = {
+ { "name", archpy_name, METH_NOARGS,
+ "name () -> String.\n\
+Return the name of the architecture as a string value." },
+ {NULL} /* Sentinel */
+};
+
+static PyTypeObject arch_object_type = {
+ PyVarObject_HEAD_INIT (NULL, 0)
+ "gdb.Architecture", /* tp_name */
+ sizeof (arch_object), /* tp_basicsize */
+ 0, /* tp_itemsize */
+ 0, /* tp_dealloc */
+ 0, /* tp_print */
+ 0, /* tp_getattr */
+ 0, /* tp_setattr */
+ 0, /* tp_compare */
+ 0, /* tp_repr */
+ 0, /* tp_as_number */
+ 0, /* tp_as_sequence */
+ 0, /* tp_as_mapping */
+ 0, /* tp_hash */
+ 0, /* tp_call */
+ 0, /* tp_str */
+ 0, /* tp_getattro */
+ 0, /* tp_setattro */
+ 0, /* tp_as_buffer */
+ Py_TPFLAGS_DEFAULT, /* tp_flags */
+ "GDB architecture object", /* tp_doc */
+ 0, /* tp_traverse */
+ 0, /* tp_clear */
+ 0, /* tp_richcompare */
+ 0, /* tp_weaklistoffset */
+ 0, /* tp_iter */
+ 0, /* tp_iternext */
+ arch_object_methods, /* tp_methods */
+ 0, /* tp_members */
+ 0, /* tp_getset */
+ 0, /* tp_base */
+ 0, /* tp_dict */
+ 0, /* tp_descr_get */
+ 0, /* tp_descr_set */
+ 0, /* tp_dictoffset */
+ 0, /* tp_init */
+ 0, /* tp_alloc */
+};
diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index 4b025db..e2eb9c5 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -167,6 +167,25 @@ frapy_type (PyObject *self, PyObject *args)
return PyInt_FromLong (type);
}

+/* Implementation of gdb.Frame.architecture (self) -> gdb.Architecture.
+ Returns the frame's architecture as a gdb.Architecture object. */
+
+static PyObject *
+frapy_arch (PyObject *self, PyObject *args)
+{
+ struct frame_info *frame = NULL; /* Initialize to appease gcc warning. */
+ frame_object *obj = (frame_object *) self;
+ volatile struct gdb_exception except;
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ FRAPY_REQUIRE_VALID (self, frame);
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+
+ return gdbarch_to_arch_object (obj->gdbarch);
+}
+
/* Implementation of gdb.Frame.unwind_stop_reason (self) -> Integer.
Returns one of the gdb.FRAME_UNWIND_* constants. */

@@ -632,6 +651,9 @@ Return the function name of the frame, or None if it can't be determined." },
{ "type", frapy_type, METH_NOARGS,
"type () -> Integer.\n\
Return the type of the frame." },
+ { "architecture", frapy_arch, METH_NOARGS,
+ "architecture () -> gdb.Architecture.\n\
+Return the architecture of the frame." },
{ "unwind_stop_reason", frapy_unwind_stop_reason, METH_NOARGS,
"unwind_stop_reason () -> Integer.\n\
Return the reason why it's not possible to find frames older than this." },
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index 7d52c06..8dff1d7 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -250,6 +250,8 @@ PyObject *pspy_get_printers (PyObject *, void *);
PyObject *objfile_to_objfile_object (struct objfile *);
PyObject *objfpy_get_printers (PyObject *, void *);

+PyObject *gdbarch_to_arch_object (struct gdbarch *gdbarch);
+
thread_object *create_thread_object (struct thread_info *tp);
thread_object *find_thread_object (ptid_t ptid);
PyObject *find_inferior_object (int pid);
@@ -263,6 +265,7 @@ struct type *type_object_to_type (PyObject *obj);
struct symtab *symtab_object_to_symtab (PyObject *obj);
struct symtab_and_line *sal_object_to_symtab_and_line (PyObject *obj);
struct frame_info *frame_object_to_frame_info (PyObject *frame_obj);
+struct gdbarch *arch_object_to_gdbarch (PyObject *obj);

void gdbpy_initialize_gdb_readline (void);
void gdbpy_initialize_auto_load (void);
@@ -293,6 +296,7 @@ void gdbpy_initialize_continue_event (void);
void gdbpy_initialize_exited_event (void);
void gdbpy_initialize_thread_event (void);
void gdbpy_initialize_new_objfile_event (void);
+void gdbpy_initialize_arch (void);

struct cleanup *make_cleanup_py_decref (PyObject *py);

diff --git a/gdb/python/python.c b/gdb/python/python.c
index b0f71a2..53ddee9 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1620,6 +1620,7 @@ message == an error message without a stack will be printed."),
gdbpy_initialize_exited_event ();
gdbpy_initialize_thread_event ();
gdbpy_initialize_new_objfile_event () ;
+ gdbpy_initialize_arch ();

observer_attach_before_prompt (before_prompt_hook);

diff --git a/gdb/testsuite/gdb.python/py-frame.exp b/gdb/testsuite/gdb.python/py-frame.exp
index aa4d937..806da94 100644
--- a/gdb/testsuite/gdb.python/py-frame.exp
+++ b/gdb/testsuite/gdb.python/py-frame.exp
@@ -38,6 +38,10 @@ gdb_breakpoint [gdb_get_line_number "Block break here."]
gdb_continue_to_breakpoint "Block break here."
gdb_py_test_silent_cmd "python bf1 = gdb.selected_frame ()" "get frame" 0

+# Test Frame.architecture() method.
+gdb_py_test_silent_cmd "python show_arch_str = gdb.execute(\"show architecture\", to_string=True)" "show arch" 0
+gdb_test "python print bf1.architecture().name() in show_arch_str" "True" "test Frame.architecture()"
+
# First test that read_var is unaffected by PR 11036 changes.
gdb_test "python print (bf1.read_var(\"i\"))" "\"stuff\"" "test i"
gdb_test "python print (bf1.read_var(\"f\"))" "\"foo\"" "test f"