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Re: [commit] [tests patchv2] FYI unwinder: tests/ update


On Thu, 2013-12-05 at 16:19 +0100, Jan Kratochvil wrote:
> On Thu, 05 Dec 2013 11:26:13 +0100, Mark Wielaard wrote:
> > The backtrace generated is:
> > 
> > TID 31941:
> > #0  0x00007fd3a47975db raise
>                          sigusr2 is missing here
> > #1  0x00007fd3a4bc7dec stdarg
> > #2  0x00007fd3a4bc7e70 backtracegen
> > #3  0x00007fd3a4bc7e79 start
> > #4  0x00007fd3a478f9d1 start_thread
> > #5  0x00007fd3a44dcb6d __clone
> 
> it is because of -O2 in build CFLAGS and tail call optimization:
> 
> Dump of assembler code for function sigusr2:
> [...]
>    0x00007f1fc53bdd43 <+19>:	mov    $0x6,%edi
>    0x00007f1fc53bdd48 <+24>:	add    $0x8,%rsp
>    0x00007f1fc53bdd4c <+28>:	jmpq   0x7f1fc53bd960 <raise(a)plt>

O, nice. So our raw backtrace was indeed correct in this case since the
tail call made the frame disappear.

> OK for check-in?

Yes, of course.

Thanks,

Mark


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