linux-kernel - Re: [PATCH] Makefile: reuse CC_VERSION

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Message-ID: <CAK7LNARKHvjTcnic=ZKntH3NY5meehQbJuBr34y9_tn8b-Ym0w@mail.gmail.com>
Date:   Sat, 6 Feb 2021 10:48:50 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Michal Marek <michal.lkml@...kovi.net>,
        Nathan Chancellor <nathan@...nel.org>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] Makefile: reuse CC_VERSION_TEXT

On Sat, Feb 6, 2021 at 7:01 AM 'Nick Desaulniers' via Clang Built
Linux <clang-built-linux@...glegroups.com> wrote:
>
> I noticed we're invoking $(CC) via $(shell) more than once to check the
> version.  Let's reuse the first string captured in $CC_VERSION_TEXT.
>
> Fixes: 315bab4e972d ("kbuild: fix endless syncconfig in case arch Makefile sets CROSS_COMPILE")


I did not touch this hunk because I have a plan
for different refactoring, but I have never got
around to do it.

Anyway, you beat me, and I will pick this up.
But, the Fixes tag is questionable because
this is code refactoring.




> Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
> ---
>  Makefile | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index a85535eb6a7d..70034d7c1051 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -557,7 +557,13 @@ ifdef building_out_of_srctree
>         { echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
>  endif
>
> -ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
> +# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
> +# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
> +# CC_VERSION_TEXT is referenced from Kconfig (so it needs export),
> +# and from include/config/auto.conf.cmd to detect the compiler upgrade.
> +CC_VERSION_TEXT = $(shell $(CC) --version 2>/dev/null | head -n 1)
> +
> +ifneq ($(findstring clang,$(CC_VERSION_TEXT)),)
>  ifneq ($(CROSS_COMPILE),)
>  CLANG_FLAGS    += --target=$(notdir $(CROSS_COMPILE:%-=%))
>  GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
> @@ -576,12 +582,6 @@ KBUILD_AFLAGS      += $(CLANG_FLAGS)
>  export CLANG_FLAGS
>  endif
>
> -# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
> -# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
> -# CC_VERSION_TEXT is referenced from Kconfig (so it needs export),
> -# and from include/config/auto.conf.cmd to detect the compiler upgrade.
> -CC_VERSION_TEXT = $(shell $(CC) --version 2>/dev/null | head -n 1)
> -
>  ifdef config-build
>  # ===========================================================================
>  # *config targets only - make sure prerequisites are updated, and descend
> --
> 2.30.0.478.g8a0d178c01-goog
>
> --
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-- 
Best Regards
Masahiro Yamada