bug#39179: 27.0.50; [PATCH] Add filter to gdb-mi register buffer

[Eli Zaretskii]

> From: Yuan Fu <casouri@gmail.com>
> Date: Sun, 2 Feb 2020 09:32:45 -0500
> Cc: 39179@debbugs.gnu.org
> 
> >> I mainly use it to display only the registers I care about, say, all
> >> the *dx registers (rdx, edx, dx) or all the r** registers (rdx, rsi,
> >> etc).
> > 
> > I understand, but why wouldn't a simple defcustom do this job?  A list
> > of registers to display is a simple thing, no?
> 
> My main concern is that defcustom wouldn’t be as convenient as the current 
> one. Right now I only need `f + .*dx` and I’m good to go, whereas defcustom I 
> need to go to customize and configure there, and come back.

Sure, but this convenience is only a significant consideration for a
feature that is supposed to be used very frequently.  I don't think
this is so in this case.

> > Really?  In what way?  I could only understand why you'd like to see
> > FP registers in some programs, but not in others.  But other than
> > that, why would you want to see this or that register?  Are you
> > frequently debugging on the machine language level?
> 
> Honestly I only used this for the bomb lab in my CS course last semester 
> where we need to debug assembly code. So if you think in real life scenarios 
> we don’t really need this _quick_ filtering and customize will cut it. I’m 
> fine with that too.

Good, then let's do it via a defcustom.

> Is your main reason of objection the (unnecessary) complexity of the code?

No, my main reason is to avoid unnecessarily cluttering the UI.

> > Then perhaps we should allow reordering the registers instead of
> > filtering their list, so that registers you want to see are at the
> > beginning?
> 
> That would be more complex that just filtering IMO. 

OK.

Thanks.