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

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Message-ID: <CAKwvOd=qh0=tU9fr60DxcJepUfg6+BkqScwifW4s8A2A=ofKpw@mail.gmail.com>
Date:   Tue, 23 Feb 2021 12:10:01 -0800
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
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 Fri, Feb 5, 2021 at 5:49 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> 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.

Hi Masahiro,
A friendly reminder to please pick this up; I don't see it yet in
linux-next. I'm ok with you dropping the fixes tag when applied.

(Otherwise, I was about to use `grep -m1` instead of `| head -n1 | grep` here.)

>
>
>
>
> > 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
> > --


-- 
Thanks,
~Nick Desaulniers