linux-kernel - Re: [PATCH v2 2/2] kbuild: consolidate Clang compiler flags

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Message-ID: <9c4868dd-82fa-aa5c-843e-e1f78ffbc7e2@google.com>
Date:   Fri, 9 Nov 2018 10:34:22 -0800
From:   Greg Hackmann <ghackmann@...gle.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Stefan Agner <stefan@...er.ch>,
        Matthias Kaehlcke <mka@...omium.org>, joel@....id.au,
        linuxppc-dev@...ts.ozlabs.org, mpe@...erman.id.au,
        Michal Marek <michal.lkml@...kovi.net>,
        LKML <linux-kernel@...r.kernel.org>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: Re: [PATCH v2 2/2] kbuild: consolidate Clang compiler flags

On 11/09/2018 10:29 AM, Nick Desaulniers wrote:
> On Mon, Nov 5, 2018 at 7:05 PM Masahiro Yamada
> <yamada.masahiro@...ionext.com> wrote:
>>
>> Collect basic Clang options such as --target, --prefix, --gcc-toolchain,
>> -no-integrated-as into a single variable CLANG_FLAGS so that it can be
>> easily reused in other parts of Makefile.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
>> ---
>>
>> Changes in v2:
>>   - Use := flavor instead of = because $(CLANG_FLAGS) is expanded soon anyway
>>
>>   Makefile | 13 ++++++-------
>>   1 file changed, 6 insertions(+), 7 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index da11700..e173a73 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -487,18 +487,17 @@ endif
>>
>>   ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
>>   ifneq ($(CROSS_COMPILE),)
>> -CLANG_TARGET   := --target=$(notdir $(CROSS_COMPILE:%-=%))
>> +CLANG_FLAGS    := --target=$(notdir $(CROSS_COMPILE:%-=%))
>>   GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))
>> -CLANG_PREFIX   := --prefix=$(GCC_TOOLCHAIN_DIR)
>> +CLANG_FLAGS    += --prefix=$(GCC_TOOLCHAIN_DIR)
>>   GCC_TOOLCHAIN  := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
>>   endif
>>   ifneq ($(GCC_TOOLCHAIN),)
>> -CLANG_GCC_TC   := --gcc-toolchain=$(GCC_TOOLCHAIN)
>> +CLANG_FLAGS    += --gcc-toolchain=$(GCC_TOOLCHAIN)
>>   endif
>> -KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)
>> -KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)
>> -KBUILD_CFLAGS += -no-integrated-as
>> -KBUILD_AFLAGS += -no-integrated-as
>> +CLANG_FLAGS    += -no-integrated-as
>> +KBUILD_CFLAGS  += $(CLANG_FLAGS)
>> +KBUILD_AFLAGS  += $(CLANG_FLAGS)
>>   endif
>>
>>   RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register
>> --
>> 2.7.4
>>
> 
> Thanks for this patch, Masahiro, it's a good simplification.
> Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
> Tested-by: Nick Desaulniers <ndesaulniers@...gle.com>
> 
> Would you mind waiting for a tested-by from Stefan, and maybe an ack
> from Greg (added to cc)?
> 

Acked-by: Greg Hackmann <ghackmann@...gle.com>