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

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Message-ID: <20170330164106.GA2130@google.com>
Date:   Thu, 30 Mar 2017 09:41:06 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
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

El Fri, Mar 31, 2017 at 01:03:02AM +0900 Masahiro Yamada ha dit:

> 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,)
> >
> 
> 
> 
> This is the same as the following commit in LLVMLinux
> except Author/Signed-off-by.
> 
> Who should the authorship really belong to?

(this time without html, sorry for the noise)

It should belong to Behan, I missed to add a 'From' tag, sorry about
that. Should I resend with the tag or can you fix it when applying the
patch?

Matthias

> 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>
> 
>