linux-kernel - Re: [PATCH v2] x86: fix early boot crash on gcc-10

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Message-ID: <20200417103808.GW20730@hirez.programming.kicks-ass.net>
Date:   Fri, 17 Apr 2020 12:38:08 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jakub Jelinek <jakub@...hat.com>
Cc:     Borislav Petkov <bp@...en8.de>,
        Sergei Trofimovich <slyfox@...too.org>,
        Michael Matz <matz@...e.de>, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>, x86@...nel.org
Subject: Re: [PATCH v2] x86: fix early boot crash on gcc-10

On Fri, Apr 17, 2020 at 10:58:59AM +0200, Jakub Jelinek wrote:
> Or go with the for (;;);, I don't think any compiler optimizes those away;
> GCC 10 for C++ can optimize away infinite loops that have some conditional
> exit because the language guarantees forward progress, but the C language
> rules are different and for unconditional infinite loops GCC doesn't
> optimize them away even if explicitly asked to -ffinite-loops.

'Funnily' there are people building the kernel with C++ :/