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Date:   Mon, 14 Jun 2021 12:18:38 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Bill Wendling <morbo@google.com>
Cc:     Kees Cook <keescook@google.com>, Jonathan Corbet <corbet@lwn.net>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Linux Doc Mailing List <linux-doc@vger.kernel.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Sami Tolvanen <samitolvanen@google.com>,
        Fangrui Song <maskray@google.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
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        johannes.berg@intel.com, oberpar@linux.vnet.ibm.com, mliska@suse.cz
Subject: Re: [PATCH v9] pgo: add clang's Profile Guided Optimization
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On Mon, Jun 14, 2021 at 11:43:12AM +0200, Peter Zijlstra wrote:
> On Sun, Jun 13, 2021 at 11:07:26AM -0700, Bill Wendling wrote:
> 
> > > > Now, for the "nointr" issue. I'll see if we need an additional change for that.
> > > >
> > > The GCOV implementation disables profiling in those directories where
> > > instrumentation would fail. We do the same. Both clang and gcc seem to
> > > treat the no_instrument_function attribute similarly.
> 
> Both seem to emit instrumentation, so they're both, simliarly, *broken*.
> 
> noinstr *MUST* disable all compiler generated instrumentation. Also see:
> 
>   https://lkml.kernel.org/r/20210527194448.3470080-1-elver@google.com
> 
> I'll go mark GCOV support as BROKEN for x86.

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