From: Nick Desaulniers <ndesaulniers@google.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg KH <gregkh@linuxfoundation.org>,
Matthias Kaehlcke <mka@chromium.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
James Y Knight <jyknight@google.com>,
Chandler Carruth <chandlerc@google.com>,
Stephen Hines <srhines@google.com>,
Kees Cook <keescook@google.com>,
groeck@chromium.org, Greg Hackmann <ghackmann@google.com>
Subject: Re: [GIT PULL] x86/build changes for v4.17
Date: Wed, 04 Apr 2018 17:46:38 +0000 [thread overview]
Message-ID: <CAKwvOdkWfawHQNiUYrOemGe3td8JvkxryUYoX5ryYRPa0QF=4g@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFyZA5t-+OyzSDDPGjDoaKsh=Erz8zuoEdDo7hOCBU6ZfQ@mail.gmail.com>
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On Wed, Apr 4, 2018 at 10:13 AM Linus Torvalds <
torvalds@linux-foundation.org> wrote:
> On Wed, Apr 4, 2018 at 9:49 AM, Nick Desaulniers
> <ndesaulniers@google.com> wrote:
> >
> > It's definitely something curious that I'll need to sit down and
> investigate
> > more. If there are other known instances, it would be good to let me
> know.
>
> The one I'm actually upset about is when a compiler goes even
> *further* and does things that are NOT EVEN allowed by the paper
> standard, much less by real code.
>
> The fact that clang by default enables "-fmerge-all-constants"
> behavior is just inexcusable. That's not just "let's do invalid
> optimizations based on undefined behavior". That's an actual "let's do
> known invalid optimizations that are explicitly disallowed even by the
> standard".
>
The LLVM developers are in agreement here:
https://bugs.llvm.org/show_bug.cgi?id=18538#c16
--
Thanks,
~Nick Desaulniers
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next prev parent reply other threads:[~2018-04-04 17:46 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-02 9:50 [GIT PULL] x86/build changes for v4.17 Ingo Molnar
2018-04-02 21:44 ` Linus Torvalds
2018-04-02 22:38 ` Matthias Kaehlcke
2018-04-03 1:26 ` Matthias Kaehlcke
2018-04-03 8:59 ` Peter Zijlstra
2018-04-03 9:51 ` Ingo Molnar
2018-04-03 12:09 ` Peter Zijlstra
2018-04-03 18:06 ` Matthias Kaehlcke
2018-04-03 21:58 ` Nick Desaulniers
2018-04-04 9:19 ` Peter Zijlstra
2018-04-04 9:38 ` Greg KH
2018-04-04 16:49 ` Nick Desaulniers
2018-04-04 17:13 ` Linus Torvalds
2018-04-04 17:46 ` Nick Desaulniers [this message]
2018-04-04 23:10 ` Nick Desaulniers
2018-04-04 16:53 ` Nick Desaulniers
2018-04-04 16:59 ` Greg KH
2018-04-04 19:26 ` James Y Knight
2018-04-04 19:42 ` Linus Torvalds
2018-04-04 22:21 ` James Y Knight
2018-04-04 22:29 ` Linus Torvalds
2018-04-05 7:08 ` Peter Zijlstra
2018-04-05 16:21 ` James Y Knight
2018-04-04 19:32 ` Josh Poimboeuf
2018-06-07 19:23 ` Nick Desaulniers
2018-06-07 20:11 ` Greg KH
2018-04-04 9:30 ` Peter Zijlstra
2018-04-04 19:17 ` Matthias Kaehlcke
2018-04-04 20:33 ` Arnd Bergmann
2018-04-04 20:58 ` Matthias Kaehlcke
2018-04-04 21:11 ` Arnd Bergmann
2018-04-04 21:46 ` Matthias Kaehlcke
2018-04-04 21:59 ` Linus Torvalds
2018-04-04 22:17 ` Matthias Kaehlcke
2018-04-04 22:39 ` Linus Torvalds
2018-04-04 23:31 ` Matthias Kaehlcke
2018-04-05 0:05 ` Linus Torvalds
2018-04-05 0:20 ` Kees Cook
2018-04-05 7:24 ` Peter Zijlstra
2018-04-05 8:04 ` Ingo Molnar
2018-04-05 8:24 ` Peter Zijlstra
2018-04-05 16:43 ` Linus Torvalds
2018-04-05 7:20 ` Peter Zijlstra
2018-04-05 17:46 ` James Y Knight
2018-04-05 18:06 ` Linus Torvalds
2018-04-05 20:51 ` James Y Knight
2018-04-05 21:13 ` Linus Torvalds
2018-04-05 22:51 ` James Y Knight
2018-04-06 2:02 ` Linus Torvalds
2018-04-05 17:47 ` James Y Knight
2018-04-04 23:04 ` Nick Desaulniers
2018-04-03 17:36 ` Linus Torvalds
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