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From: dwk <dwks42@gmail.com>
Date: Mon, 25 Feb 2019 15:54:00 -0000
Message-ID: <CAPkwjGtoLAPg6dnPOp5fe9-dqFDerhmATESu_wZaUtOOQOp4hA@mail.gmail.com>
Subject: Re: Is nexti confused by pushq?
To: David Griffiths <dgriffiths@undo.io>
Cc: GDB <gdb@sourceware.org>
Content-Type: text/plain; charset="UTF-8"
X-SW-Source: 2019-02/txt/msg00063.txt.bz2

I encounter this frequently, although I don't have a minimal case yet
either. I think it may have something to do with symbol information, as
I've only encountered the case when symbol information is not present (as
in the example you gave). stepi always works but nexti sometimes turns into
a continue, I assumed because it was unable to figure out where the "next"
instruction was somehow in the absence of symbols.

dwk

On Mon, Feb 25, 2019, 10:41 AM David Griffiths <dgriffiths@undo.io> wrote:

> Hi, when I get to the following instructions:
>
>   0x00007fffe192413e: rex.W pushq 0x28(%rsp)
>   0x00007fffe1924143: rex.W popq (%rsp)
>   0x00007fffe1924147: callq  0x00007fffe1045de0
>
> and do "nexti" at the first, it doesn't stop at the second but instead acts
> as though I'd done "continue". For some reason I can't reproduce with a
> little test though.
>
> (gdb 8.1 on Ubuntu 16.04)
>
> BTW I'm doing nexti programmatically and trying to avoid looking at the
> next instruction to decide whether to do stepi or nexti.
>
> Cheers,
>
> David
>
> --
>
> David Griffiths, Senior Software Engineer
>
> Undo <https://undo.io> | Resolve even the most challenging software
> defects
> with software flight recorder technology
>
> Software reliability report: optimizing the software supplier and customer
> relationship
> <
> https://info.undo.io/software-reliability-report-optimizing-supplier-and-customer-relationship
> >
>