Re: [PATCH] Add Frame.read_register to Python API

[Alexander Smundak <asmundak at google dot com>]

> 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.

Should I mail these two as a single patch or as two separate patches?

> Alexander> +      FRAPY_REQUIRE_VALID (self, frame);
> Alexander> +      if (!PyArg_ParseTuple (args, "i", &regnum))
> Alexander> +    {
> Alexander> +      const char *regnum_str;
> Alexander> +      PyErr_Clear();  /* Clear PyArg_ParseTuple failure above.  */
> Alexander> +      if (PyArg_ParseTuple (args, "s", &regnum_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.

Did that, and then started doubting whether it is really necessary to read
a register by its (very arch-specific) number. The new version supports
reading the register by the name. Another change is that it now throws
an exception if the name is wrong.

> 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.
IMHO it's borderline arch-specific -- it is runnable on any platform,
although it will not be testing much on any but x86-64. There hasn't
been any arch-specific tests for Python so far, so I am not sure what to do.

Here's the new version (style violations have been addressed, too):

The ability to read registers is needed to use Frame Filter API to
display the frames created by JIT compilers.

gdb/Changelog
2014-06-11  Sasha Smundak  <asmundak@google.com>

* python/py-frame.c (frapy_read_register): New function.

2014-06-11  Sasha Smundak  <asmundak@google.com>

* python.texi (Frames in Python): Add read_register description.

2014-06-11  Sasha Smundak  <asmundak@google.com>

* gdb.python/py-frame.exp: Test Frame.read_register.

Attachment: frame-read-register-patch-3.txt
Description: Text document