From: Nathan Chancellor <natechancellor@gmail.com>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Michal Marek <michal.lkml@markovi.net>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] kbuild: remove cc-option test of -fno-merge-all-constants
Date: Thu, 10 Sep 2020 09:33:11 -0700 [thread overview]
Message-ID: <20200910163311.GB3119896@ubuntu-n2-xlarge-x86> (raw)
In-Reply-To: <20200910135120.3527468-2-masahiroy@kernel.org>
On Thu, Sep 10, 2020 at 10:51:18PM +0900, Masahiro Yamada wrote:
> The minimal compiler versions, GCC 4.9 and Clang 10 support this flag.
>
> Here is the godbolt:
> https://godbolt.org/z/8T4177
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
For what it's worth, the commit that introduced this block is going to
be reverted:
https://lore.kernel.org/mm-commits/20200903201518.JKrRS%25akpm@linux-foundation.org/
Regardless, it was introduced in LLVM 2.7.0 in commit
f9d41df0930986c52e198292cf875eb5d1761ece.
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>
> Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index 059b36f2ea53..1b6abecc5cab 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -927,7 +927,7 @@ KBUILD_CFLAGS += -fno-strict-overflow
> # clang sets -fmerge-all-constants by default as optimization, but this
> # is non-conforming behavior for C and in fact breaks the kernel, so we
> # need to disable it here generally.
> -KBUILD_CFLAGS += $(call cc-option,-fno-merge-all-constants)
> +KBUILD_CFLAGS += -fno-merge-all-constants
>
> # for gcc -fno-merge-all-constants disables everything, but it is fine
> # to have actual conforming behavior enabled.
> --
> 2.25.1
>
next prev parent reply other threads:[~2020-09-10 16:44 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 13:51 [PATCH 1/4] kbuild: remove cc-option test of -fno-strict-overflow Masahiro Yamada
2020-09-10 13:51 ` [PATCH 2/4] kbuild: remove cc-option test of -fno-merge-all-constants Masahiro Yamada
2020-09-10 16:33 ` Nathan Chancellor [this message]
2020-09-10 16:41 ` Masahiro Yamada
2020-09-10 13:51 ` [PATCH 3/4] kbuild: remove cc-option test of -fno-stack-check Masahiro Yamada
2020-09-10 16:37 ` Nathan Chancellor
2020-09-10 13:51 ` [PATCH 4/4] kbuild: remove cc-option test of -Werror=date-time Masahiro Yamada
2020-09-10 16:43 ` Nathan Chancellor
2020-09-10 16:26 ` [PATCH 1/4] kbuild: remove cc-option test of -fno-strict-overflow Nathan Chancellor
2020-09-11 15:22 ` Will Deacon
2020-09-14 12:51 ` Masahiro Yamada
2020-09-14 13:20 ` Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200910163311.GB3119896@ubuntu-n2-xlarge-x86 \
--to=natechancellor@gmail.com \
--cc=clang-built-linux@googlegroups.com \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masahiroy@kernel.org \
--cc=michal.lkml@markovi.net \
--cc=mingo@redhat.com \
--cc=ndesaulniers@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).