Re: [PATCH 4/8] gdb/s390: Fill gen_return_address hook.

[Eli Zaretskii <eliz@gnu.org>]

> Cc: Eli Zaretskii <eliz@gnu.org>,
>         Marcin Kościelnicki
>  <koriakin@0x04.net>,
>         gdb-patches@sourceware.org
> From: Pedro Alves <palves@redhat.com>
> Date: Fri, 11 Mar 2016 17:02:19 +0000
> 
> >   @item $_ret
> >   Collect the return address.  This is helpful if you want to see more
> > -of a backtrace.
> > +of a backtrace.  Note that the return address can not always be
> > +determined reliably, and a wrong address may be collected instead.
> > +The reliability is usually higher for tracepoints at function entry.
> 
> Hmm, this reads a bit as if the backtrace will be incorrect/bogus
> later on, which is not true.
> 
> How about a merge of your suggestion with Marcin's previous reply,
> and some extras on top:
> 
> @item $_ret
> Collect the set of memory addresses and/or registers necessary to compute
> the frame's return address.  This is helpful if you want to see 
> more of a backtrace.
> 
> @emph{Note:} The necessary set can not always be reliability determined up
> front, and the wrong address / registers may end up collected instead.
> The reliability is usually higher for tracepoints at function entry.
> When this happens, backtracing will stop because the return address
> is found unavailable (unless another collect rule happened to match it).

Maybe it's me, but I don't see the significant difference between
these two versions.  (And there's a typo in the second one:
"reliability" should be "reliably".)

Thanks.