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

Andreas Arnez
2016-03-11T16:45:31Z

On Fri, Mar 11 2016, Pedro Alves wrote:

> On 03/11/2016 03:31 PM, Andreas Arnez wrote:
>> So I'm OK with the patch. Please add a small comment stating that this
>> is a best-can-do approach that usually works near function entry and may
>> yield wrong results otherwise.
>
> I think that should be put in the manual, even. Users will also trip on
> this, not just our tests.

Right, I thought about this as well. How about this?

-- >8 --
Subject: [PATCH] Document possible unreliability of `$_ret'

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 4ec0ec1..a14fe19 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -12863,7 +12863,9 @@ Collect all local variables.

@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.

@item $_probe_argc
Collects the number of arguments from the static probe at which the