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Date: Tue, 1 Oct 2013 10:42:47 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [GIT PULL] perf fixes
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* Andi Kleen <ak@linux.intel.com> wrote:

> > > Hmm, works for me. In fact I wrote it to fix a perf top issue.
> >
> > What 'issue' and why wasn't it described in the changelog more 
> > accurately?
> >
> > The blurb you wrote in the changelog:
> > 
> > | The libbfd C++ demangler doesn't seem to deal with cloned functions, 
> > | like symbol.clone.NUM.
> > |
> > | Just strip the dot part before demangling and add it back later.
> > 
> > Only alludes to a C++ symbol resolution annoyance and thus isn't very 
> > informative.
> 
> The issue was that I saw a long unreadable line noise string in 
> report/top, instead of a demangled function. After I stripped the 
> postfix I got the demangled symbol as expected.

We obviously don't want to trade output annoyances for crashes, nor does 
it justify the code uglies you introduced with the patch - which made the 
code obviously unrobust.

My guess would be that maybe it's the cast of a const pointer that 
possibly broke GCC's aliasing detection on Markus's system or so. But 
maybe there's a more direct bug in the code as well, the code you added is 
too ugly to be reviewed efficiently, please send a cleaned up version.

Thanks,

	Ingo