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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 11 May 2020 11:36:43 -0700
Message-ID: <CAHk-=whkz12DeKOt3iw19Ey=c5HkXH+4disNJ3DwZuSDr-Tt5w@mail.gmail.com>
Subject: Re: [PATCH] x86: support i386 with Clang
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        David Woodhouse <dwmw2@infradead.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Dmitry Golovin <dima@golovin.in>,
        Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
        Christoph Lameter <cl@linux.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>
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On Mon, May 11, 2020 at 11:24 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I guess I should just test it, since I have that clang tree.

No, clang doesn't seem to handle it even with __builtin_choose_expr(),
and has that

     invalid input size for constraint 'qi'

even when it's in a side that is never chosen.

Very annoying. A lot of our magic macros are literally about "pick one
case when the others are not valid for this type".

             Linus