Add Frame.read_register to Python API
Commit Message
On Mon, Jun 9, 2014 at 12:25 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> When 2 changes are in the same node, write them one after the other,
> and have only one "(Node Name)" thing.
Done.
>> +* Python Scripting
>> + Access frame registers
>
> This is an incomplete sentence. I guess you meant something like
> You can now access frame registers from Python scripts.
Done.
>> +Return the value of @var{register} in this frame. The @var{register}
>> +argument must be a string (e.g., 'rsp' or 'r1'), or a register number.
> ^^^^^^^^^^^^^
> These should be in @code instead of quotes.
Added the code but retained the quotes, because it's string literal.
>> +Returns @code{Gdb.Value} object.
> ^
> "a" missing here.
Done.
Here it is again:
The ability to read registers is needed to use Frame Filter API to
display the frames created by JIT compilers.
gdb/Changelog
2014-06-09 Sasha Smundak <asmundak@google.com>
* python/py-frame.c (frapy_read_register): New function.
2014-06-09 Sasha Smundak <asmundak@google.com>
* python.texi (Writing a Frame Filter): Fix example code.
(Frames in Python): Fix reference in find_sal description.
Add read_register description.
2014-06-09 Sasha Smundak <asmundak@google.com>
* gdb.python/py-frame.exp: Test Frame.read_register.
Comments
>>>>> "Alexander" == Alexander Smundak <asmundak@google.com> writes:
Thanks for your patch.
There's a few nits but nothing very serious.
Alexander> diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
Alexander> index 4688783..14564eb 100644
Alexander> --- a/gdb/doc/python.texi
Alexander> +++ b/gdb/doc/python.texi
Alexander> @@ -2046,9 +2046,10 @@ class InlinedFrameDecorator(FrameDecorator):
Alexander> def __init__(self, fobj):
Alexander> super(InlinedFrameDecorator, self).__init__(fobj)
Alexander> + self.fobj = fobj
Alexander> def function(self):
Alexander> - frame = fobj.inferior_frame()
Alexander> + frame = self.fobj.inferior_frame()
Alexander> name = str(frame.name())
I think this is a nice fix but it seems unrelated to the patch at hand.
Alexander> @defun Frame.find_sal ()
Alexander> -Return the frame's symtab and line object.
Alexander> +Return the frame's @code{gdb.Symtab_and_line} object.
Likewise.
Alexander> +/* Implementation of gdb.Frame.read_register (self, register) -> gdb.Value.
Alexander> + Returns the value of a register in this frame. */
Alexander> +static PyObject *
Alexander> +frapy_read_register (PyObject *self, PyObject *args)
Alexander> +{
The gdb style requests a blank line between the intro comment and the
function.
Alexander> + struct frame_info *frame;
Alexander> + volatile struct gdb_exception except;
Alexander> + int regnum = -1;
Alexander> + struct value *val = NULL;
Alexander> + TRY_CATCH (except, RETURN_MASK_ALL)
Alexander> + {
... and also a blank line between variable declarations and code
(wherever this occurs -- there's a case in the patch in a nested block).
Alexander> + FRAPY_REQUIRE_VALID (self, frame);
Alexander> + if (!PyArg_ParseTuple (args, "i", ®num))
Alexander> + {
Alexander> + const char *regnum_str;
Alexander> + PyErr_Clear(); /* Clear PyArg_ParseTuple failure above. */
Alexander> + if (PyArg_ParseTuple (args, "s", ®num_str))
Alexander> + {
Alexander> + regnum = user_reg_map_name_to_regnum (get_frame_arch (frame),
Alexander> + regnum_str,
Alexander> + strlen (regnum_str));
Alexander> + }
Alexander> + }
I tend to think this would be clearer if the arguments were only parsed
once and then explicit type checks were applied to the resulting object.
Alexander> + return val ? value_to_value_object (val) : NULL;
gdb style requests an explicit NULL check, like "return val != NULL ? ...".
Alexander> +# On x86-64, PC is register 16.
Alexander> +gdb_test "python print ('result = %s' % ((f0.architecture().name() != 'i386:x86-64') or f0.read_register('pc') == f0.read_register(16)))" \
Alexander> + "True" \
Alexander> + "test Frame.read_register(regnum)"
A test that is arch-specific needs to be conditionalized somehow.
Tom
@@ -3,6 +3,9 @@
*** Changes since GDB 7.7
+* Python Scripting
+ You can now access frame registers from Python scripts.
+
* New command line options
-D data-directory
@@ -2046,9 +2046,10 @@ class InlinedFrameDecorator(FrameDecorator):
def __init__(self, fobj):
super(InlinedFrameDecorator, self).__init__(fobj)
+ self.fobj = fobj
def function(self):
- frame = fobj.inferior_frame()
+ frame = self.fobj.inferior_frame()
name = str(frame.name())
if frame.type() == gdb.INLINE_FRAME:
@@ -3585,10 +3586,16 @@ Return the frame called by this frame.
@end defun
@defun Frame.find_sal ()
-Return the frame's symtab and line object.
+Return the frame's @code{gdb.Symtab_and_line} object.
@xref{Symbol Tables In Python}.
@end defun
+@defun Frame.read_register (register)
+Return the value of @var{register} in this frame. The @var{register}
+argument must be a string (e.g., @code{'rsp'} or @code{'r1'}), or a
+register number. Returns a @code{Gdb.Value} object.
+@end defun
+
@defun Frame.read_var (variable @r{[}, block@r{]})
Return the value of @var{variable} in this frame. If the optional
argument @var{block} is provided, search for the variable from that
@@ -28,6 +28,7 @@
#include "python-internal.h"
#include "symfile.h"
#include "objfiles.h"
+#include "user-regs.h"
typedef struct {
PyObject_HEAD
@@ -235,6 +236,38 @@ frapy_pc (PyObject *self, PyObject *args)
return gdb_py_long_from_ulongest (pc);
}
+/* Implementation of gdb.Frame.read_register (self, register) -> gdb.Value.
+ Returns the value of a register in this frame. */
+static PyObject *
+frapy_read_register (PyObject *self, PyObject *args)
+{
+ struct frame_info *frame;
+ volatile struct gdb_exception except;
+ int regnum = -1;
+ struct value *val = NULL;
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ FRAPY_REQUIRE_VALID (self, frame);
+ if (!PyArg_ParseTuple (args, "i", ®num))
+ {
+ const char *regnum_str;
+ PyErr_Clear(); /* Clear PyArg_ParseTuple failure above. */
+ if (PyArg_ParseTuple (args, "s", ®num_str))
+ {
+ regnum = user_reg_map_name_to_regnum (get_frame_arch (frame),
+ regnum_str,
+ strlen (regnum_str));
+ }
+ }
+ if (regnum >= 0)
+ {
+ val = value_of_register (regnum, frame);
+ }
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+ return val ? value_to_value_object (val) : NULL;
+}
+
/* Implementation of gdb.Frame.block (self) -> gdb.Block.
Returns the frame's code block. */
@@ -674,6 +707,9 @@ Return the reason why it's not possible to find frames older than this." },
{ "pc", frapy_pc, METH_NOARGS,
"pc () -> Long.\n\
Return the frame's resume address." },
+ { "read_register", frapy_read_register, METH_VARARGS,
+ "read_register (register) -> gdb.Value\n\
+Return the value of the register in the frame." },
{ "block", frapy_block, METH_NOARGS,
"block () -> gdb.Block.\n\
Return the frame's code block." },
@@ -94,3 +94,16 @@ gdb_test "python print ('result = %s' % f0.read_var ('variable_which_surely_does
gdb_test "python print ('result = %s' % f0.read_var ('a'))" " = 1" "test Frame.read_var - success"
gdb_test "python print ('result = %s' % (gdb.selected_frame () == f1))" " = True" "test gdb.selected_frame"
+
+# Can read SP register.
+gdb_test "python print ('result = %s' % f0.read_register('sp'))" \
+ " = 0x\[0-9a-fA-F\]+" \
+ "test Frame.read_register(fp)"
+# PC value obtained via read_register is as expected.
+gdb_test "python print ('result = %s' % (f0.read_register('pc').cast(gdb.lookup_type('unsigned long')) == f0.pc()))" \
+ "True" \
+ "test Frame.read_register(pc)"
+# On x86-64, PC is register 16.
+gdb_test "python print ('result = %s' % ((f0.architecture().name() != 'i386:x86-64') or f0.read_register('pc') == f0.read_register(16)))" \
+ "True" \
+ "test Frame.read_register(regnum)"