Re: [GIT PULL] perf fixes

From: Ingo Molnar
Date: Tue Oct 01 2013 - 04:42:58 EST



* Andi Kleen <ak@xxxxxxxxxxxxxxx> 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
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