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From: Peter Zijlstra <peterz@infradead.org>
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Joe Perches <joe@perches.com>, Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, Kan Liang <kan.liang@linux.intel.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Kees Cook <keescook@chromium.org>, Shawn Landden <shawn@git.icu>
Subject: Re: [PATCH] perf/x86/intel: Mark expected switch fall-throughs
Date: Tue, 25 Jun 2019 09:18:46 +0200	[thread overview]
Message-ID: <20190625071846.GN3436@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CANiq72mMS6tHcP8MHW63YRmbdFrD3ZCWMbnQEeHUVN49v7wyXQ@mail.gmail.com>

On Tue, Jun 25, 2019 at 12:28:23AM +0200, Miguel Ojeda wrote:
> On Mon, Jun 24, 2019 at 10:53 PM Gustavo A. R. Silva
> <gustavo@embeddedor.com> wrote:
> >
> > Once the C++17 `__attribute__((fallthrough))` is more widely handled by C compilers,
> > static analyzers, and IDEs, we can switch to using that instead. Also, we are a few
> > warnings away (less than five) from being able to enable -Wimplicit-fallthrough. After
> > this option has been finally enabled (in v5.3) we can easily go and replace the comments
> > to whatever we agree upon.
> 
> Indeed -- the decision last year was to wait for a while since not
> everyone had support for it. My branch is waiting here:
> 
>     https://github.com/ojeda/linux/tree/compiler-attributes-fallthrough
> 
> The good news is that there is some progress. For instance, LLVM is
> working on supporting the GNU spelling:
> 
>     https://reviews.llvm.org/D63260
>     https://bugs.llvm.org/show_bug.cgi?id=37135
>     https://github.com/ClangBuiltLinux/linux/issues/235

Can it build a kernel without patches yet? That is, why should I care
what LLVM does?

> Also note that C2x may get [[fallthrough]]. See N2267 and N2335. At
> that point, surely tools/IDEs/analyzers will support it :-) The
> question is whether we want to wait that long to replace the comments.

#define __fallthrough [[fallthrough]]

right?

  reply	other threads:[~2019-06-25  7:19 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-24 16:19 [PATCH] perf/x86/intel: Mark expected switch fall-throughs Gustavo A. R. Silva
2019-06-24 19:31 ` Peter Zijlstra
2019-06-24 19:45   ` Joe Perches
2019-06-24 20:37     ` Peter Zijlstra
2019-06-24 20:53       ` Gustavo A. R. Silva
2019-06-24 20:57         ` Joe Perches
2019-06-25  7:20           ` Peter Zijlstra
2019-06-24 22:28         ` Miguel Ojeda
2019-06-25  7:18           ` Peter Zijlstra [this message]
2019-06-25 12:47             ` Miguel Ojeda
2019-06-25 18:15               ` Nick Desaulniers
2019-06-25 22:29                 ` Joe Perches
2019-06-25 22:57                   ` Nick Desaulniers
2019-06-25 23:25                     ` Joe Perches
2019-06-26  8:49                 ` Peter Zijlstra
2019-06-26 22:14                   ` Nick Desaulniers
2019-06-27  7:12                     ` Peter Zijlstra
2019-06-28 13:31                       ` Peter Zijlstra
2019-06-28 18:44                         ` Nick Desaulniers
2019-06-29  7:10                           ` Peter Zijlstra
2019-06-25 17:12             ` Kees Cook
2019-06-25 18:05               ` Nathan Chancellor
2019-06-25 19:53                 ` Thomas Gleixner
2019-06-25 20:27                   ` Nathan Chancellor
2019-06-25 20:37                     ` Nick Desaulniers
2019-06-25 21:47                     ` Thomas Gleixner
2019-06-26  5:10                       ` Nathan Chancellor
2019-06-26 15:18                         ` Thomas Gleixner
2019-06-26 19:00                           ` Nathan Chancellor
2019-06-26 19:46                             ` Thomas Gleixner
2019-06-26 20:03                               ` Nathan Chancellor
2019-06-26  9:24                       ` Peter Zijlstra
2019-06-26  9:55                         ` Peter Zijlstra
2019-06-26 22:23                           ` Nick Desaulniers
2019-06-27  7:35                             ` Peter Zijlstra
2019-06-26 10:43                         ` Peter Zijlstra
2019-06-26 22:15                         ` Nick Desaulniers
2019-06-27  7:16                           ` Peter Zijlstra
2019-06-26 16:30                       ` Peter Zijlstra
2019-06-26 22:33                         ` Nick Desaulniers
2019-06-26 23:11                           ` Thomas Gleixner
2019-06-27  7:11                           ` Peter Zijlstra
2019-06-25 23:46                     ` Arnaldo Carvalho de Melo
2019-06-26  5:14                       ` Nathan Chancellor
2019-06-25 20:09                 ` Kees Cook
2019-06-26  8:06               ` Peter Zijlstra
2019-06-25  7:15         ` Peter Zijlstra
2019-07-25 16:27 ` [tip:perf/urgent] " tip-bot for Gustavo A. R. Silva
2019-07-25 17:06   ` Borislav Petkov
2019-07-25 17:35     ` Peter Zijlstra
2019-07-25 23:18       ` Joe Perches
2019-07-25 23:28         ` Kees Cook

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