Re: [RFA/RFC] mips tracepoint: fix Bug 12013

Kevin Buettner
2010-12-22T15:36:56Z

On Wed, 22 Dec 2010 15:12:22 +0800
Hui Zhu <teawater@gmail.com> wrote:

> > You might consider implementing a new gdbarch method which provides a
> > mapping from pseudo register numbers to raw register numbers. __The
> > trace machinery could use such a mapping to find the corresponding raw
> > register(s) when presented with a pseudo register. __I can think of
> > several potential pitfalls with this approach, but I think the idea is
> > worth exploring.
>
> Thanks Kevin. I will do it.

Please look at Pedro's reply. He has outlined a better approach.

> And I make a patch to add some comments from your mail to mips_register_name.
> Wish it can help other people.
>
> Please help me review it.

Okay, see below...

> 2010-12-22 Hui Zhu <teawater@gmail.com>
>
> * mips-tedp.c (mips_register_name): Add comments.
>
> ---
> mips-tdep.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> --- a/mips-tdep.c
> +++ b/mips-tdep.c
> @@ -454,7 +454,12 @@ mips_register_name (struct gdbarch *gdba
> enum mips_abi abi = mips_abi (gdbarch);
>
> /* Map [gdbarch_num_regs .. 2*gdbarch_num_regs) onto the raw registers,
> - but then don't make the raw register names visible. */
> + but then don't make the raw register names visible.
> + Because It is possible to debug a 64-bit device using a 32-bit programming
> + model. In such instances, the raw registers are configured to be
> + 64-bits wide, while the pseudo registers are configured to be 32-bits
> + wide. The registers that the user sees - the pseudo registers - match
> + the user's expectations given the programming model being used. */

Could you revise the comment to read as follows?

/* Map [gdbarch_num_regs .. 2*gdbarch_num_regs) onto the raw registers,
but do not make the raw register names visible. This (upper)
range of user visible register numbers are the
pseudo-registers.

This approach was adopted accomodate the following scenario:
It is possible to debug a 64-bit device using a 32-bit
programming model. In such instances, the raw registers are
configured to be 64-bits wide, while the pseudo registers are
configured to be 32-bits wide. The reigsters that the user
sees - the pseudo registers - match the users expectations
given the programming model being used. */

Please allow several days for others to tweak my suggested wording. If
there are no further comments on the above wording, feel free to commit
it.

Thanks,

Kevin