From: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Arnd Bergmann <arnd@arndb.de>, Miguel Ojeda <ojeda@kernel.org>,
Marco Elver <elver@google.com>,
Sami Tolvanen <samitolvanen@google.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
Randy Dunlap <rdunlap@infradead.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP*
Date: Fri, 26 Feb 2021 04:58:38 +0100 [thread overview]
Message-ID: <CANiq72=5t1maOv1FerMLRVCRos_yv-iQGLzB21Z+aYxTXLy8gA@mail.gmail.com> (raw)
In-Reply-To: <20210225201801.GA3119@MSI.localdomain>
On Thu, Feb 25, 2021 at 9:18 PM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Indeed. Any wins that we can get with compile time, we should take.
> Clang is being widely used in production systems now so I feel like with
> a trivial change plus user visible impact, it should be backported.
>
> Not to mention that the generated code in theory should be better
> because it is the compiler's builtin, rather than a hand rolled one, AND
> this is technically a regression, given that it worked before compiler.h
> was split.
Compilation speed shouldn't be an argument for a stable change unless
it is something egregious like a 50% that may affect users or tightly
timed CIs.
Fixing an important runtime regression is a stronger argument, but the
patch doesn't show what the effects are, so it isn't justified (yet).
Please note that this kind of change touches a lot of code all over
the place, which could always trigger other runtime regressions or
even bad codegen (yes, very unlikely, but it happens).
Cheers,
Miguel
next prev parent reply other threads:[~2021-02-26 3:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-25 16:45 [PATCH] linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP* Arnd Bergmann
2021-02-25 19:29 ` Nathan Chancellor
2021-02-25 20:03 ` Kees Cook
2021-02-25 20:06 ` Andrew Morton
2021-02-25 20:14 ` Kees Cook
2021-02-25 20:18 ` Nathan Chancellor
2021-02-26 3:58 ` Miguel Ojeda [this message]
2021-02-26 3:34 ` Miguel Ojeda
2021-02-25 21:01 ` Nick Desaulniers
2021-02-26 7:47 ` Luc Van Oostenryck
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