linux-kernel - Re: [PATCH] kbuild: use -Oz instead of -Os when using clang

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Date:   Fri, 31 Mar 2017 01:03:02 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Michal Marek <mmarek@...e.com>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Behan Webster <behanw@...verseincode.com>,
        Greg Hackmann <ghackmann@...gle.com>,
        Grant Grundler <grundler@...omium.org>,
        Michael Davidson <md@...gle.com>,
        Peter Foley <pefoley2@...oley.com>
Subject: Re: [PATCH] kbuild: use -Oz instead of -Os when using clang

2017-03-28 10:19 GMT+09:00 Matthias Kaehlcke <mka@...omium.org>:
> This generates smaller resulting object code when compiled with clang.
>
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>  Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index b2faa9319372..66bcdbf58371 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -638,7 +638,8 @@ KBUILD_CFLAGS       += $(call cc-option,-fdata-sections,)
>  endif
>
>  ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
> -KBUILD_CFLAGS  += -Os $(call cc-disable-warning,maybe-uninitialized,)
> +KBUILD_CFLAGS  += $(call cc-option,-Oz,-Os)
> +KBUILD_CFLAGS  += $(call cc-disable-warning,maybe-uninitialized,)
>  else
>  ifdef CONFIG_PROFILE_ALL_BRANCHES
>  KBUILD_CFLAGS  += -O2 $(call cc-disable-warning,maybe-uninitialized,)
> --
> 2.12.2.564.g063fe858b8-goog
>



This is the same as the following commit in LLVMLinux
except Author/Signed-off-by.

Who should the authorship really belong to?



commit 186e62808239c603bfa308d5ea994a10d67bb409
Author: Behan Webster <behanw@...verseincode.com>
Date:   Thu Oct 16 14:28:54 2014 +0200

    LLVMLinux: use -Oz instead of -Os when using clang

    This generates smaller resulting object code when compiled with clang.

    Signed-off-by: Behan Webster <behanw@...verseincode.com>


-- 
Best Regards
Masahiro Yamada