[Regression] [PATCH] Do not print empty-group regs when printing general ones

[Shahab Vahedi]

On Fri, Feb 28, 2020 at 10:31:26AM -0300, Luis Machado wrote:
> 
> 
> On 2/28/20 10:22 AM, Christian Biesinger wrote:
> > On Fri, Feb 28, 2020 at 7:08 AM Luis Machado <luis.machado@linaro.org> wrote:
> > > 
> > > On 1/31/20 7:34 AM, Shahab Vahedi wrote:
> > > > This patch was reviewed once (as OK):
> > > > https://sourceware.org/ml/gdb-patches/2020-01/msg00613.html
> > > > 
> > > > Could someone review/merge it?
> > > > 
> > > > 
> > > > Cheers,
> > > > Shahab
> > > > 
> > > 
> > > FTR, this has broken general register printing for ARM/AArch64. Now
> > > "info reg" shows nothing.
> > > 
> > > Given there are already remote stubs, probes and gdbservers running out
> > > there, this is an undesirable change to have.
> > > 
> > > I had an IRC chat with Christian and he pointed me at some documentation
> > > stating empty-group registers should not be printed, but i think this is
> > > a case where the implementation has diverged from the documentation.
> > > 
> > > https://sourceware.org/gdb/current/onlinedocs/gdb/Target-Description-Format.html#Target-Description-Format
> > > 
> > > We could probably patch up any non-standard target description XML's
> > > from now on, but the existing behavior may have to be preserved.
> > 
> > Most targets under features/ do not specify group="general" in their
> > XML files for anything (only S/390 does); it seems like that should
> > maybe be fixed either way?
> 
> I agree.

The documentation [1] says:
If no group is specified, GDB will not display the register in info registers

[1]
https://sourceware.org/gdb/onlinedocs/gdb/Target-Description-Format.html#Target-Description-Format