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From:   Florian Weimer <fw@deneb.enyo.de>
To:     Mark Wielaard <mark@klomp.org>
Cc:     Andi Kleen <andi@firstfloor.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Stephane Eranian <eranian@google.com>,
        linux-toolchains@vger.kernel.org,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        "Phillips\, Kim" <kim.phillips@amd.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: Additional debug info to aid cacheline analysis
References: <20201006131703.GR2628@hirez.programming.kicks-ass.net>
        <CABPqkBSkdqXjm6QuF9j6AO8MUnt1yZ_cA2PV=Qo8e4wKmK_6Ug@mail.gmail.com>
        <20201008070231.GS2628@hirez.programming.kicks-ass.net>
        <50338de81b34031db8637337f08b89b588476211.camel@klomp.org>
        <20201008212259.gdhlwdswn5pu4zos@two.firstfloor.org>
        <20201010205836.GA2666@wildebeest.org>
Date:   Sun, 11 Oct 2020 14:15:18 +0200
In-Reply-To: <20201010205836.GA2666@wildebeest.org> (Mark Wielaard's message
        of "Sat, 10 Oct 2020 22:58:36 +0200")
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* Mark Wielaard:

> Yes, that would work. I don't know what the lowest supported GCC
> version is, but technically it was definitely fixed in 4.10.0, 4.8.4
> and 4.9.2. And various distros would probably have backported the
> fix. But checking for 5.0+ would certainly give you a good version.
>
> How about the attached?

Would it be possible to test for the actual presence of the bug, using
-fcompare-debug?

(But it seems to me that the treatment of this particular compiler bug
is an outlier: other equally tricky bugs do not receive this kind of
attention.)