linux-kernel - Re: [PATCH] kbuild: Switch to 'f' variants of integrated assembler flag

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Date:   Mon, 16 Aug 2021 13:48:45 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Nathan Chancellor <nathan@...nel.org>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] kbuild: Switch to 'f' variants of integrated assembler flag

On Mon, Aug 16, 2021 at 1:37 PM Nathan Chancellor <nathan@...nel.org> wrote:
>
> It has been brought up a few times in various code reviews that clang
> 3.5 introduced -f{,no-}integrated-as as the preferred way to enable and
> disable the integrated assembler, mentioning that -{no-,}integrated-as
> are now considered legacy flags.
>
> Switch the kernel over to using those variants in case there is ever a
> time where clang decides to remove the non-'f' variants of the flag.
>
> Link: https://releases.llvm.org/3.5.0/tools/clang/docs/ReleaseNotes.html#new-compiler-flags
> Signed-off-by: Nathan Chancellor <nathan@...nel.org>

Thanks for the patch! Want to fix
tools/testing/selftests/rseq/Makefile and
tools/testing/selftests/sched/Makefile, too? Either way...
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

> ---
>  scripts/Makefile.clang | 4 ++--
>  scripts/as-version.sh  | 6 +++---
>  2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang
> index 3ae63bd35582..4cce8fd0779c 100644
> --- a/scripts/Makefile.clang
> +++ b/scripts/Makefile.clang
> @@ -23,11 +23,11 @@ CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
>  endif # CROSS_COMPILE
>
>  ifeq ($(LLVM_IAS),0)
> -CLANG_FLAGS    += -no-integrated-as
> +CLANG_FLAGS    += -fno-integrated-as
>  GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
>  CLANG_FLAGS    += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
>  else
> -CLANG_FLAGS    += -integrated-as
> +CLANG_FLAGS    += -fintegrated-as
>  endif
>  CLANG_FLAGS    += -Werror=unknown-warning-option
>  KBUILD_CFLAGS  += $(CLANG_FLAGS)
> diff --git a/scripts/as-version.sh b/scripts/as-version.sh
> index 8b9410e329df..a0fc366728f1 100755
> --- a/scripts/as-version.sh
> +++ b/scripts/as-version.sh
> @@ -21,13 +21,13 @@ get_canonical_version()
>         echo $((10000 * $1 + 100 * ${2:-0} + ${3:-0}))
>  }
>
> -# Clang fails to handle -Wa,--version unless -no-integrated-as is given.
> -# We check -(f)integrated-as, expecting it is explicitly passed in for the
> +# Clang fails to handle -Wa,--version unless -fno-integrated-as is given.
> +# We check -fintegrated-as, expecting it is explicitly passed in for the
>  # integrated assembler case.
>  check_integrated_as()
>  {
>         while [ $# -gt 0 ]; do
> -               if [ "$1" = -integrated-as -o "$1" = -fintegrated-as ]; then
> +               if [ "$1" = -fintegrated-as ]; then
>                         # For the intergrated assembler, we do not check the

^ want to fix this typo, too? s/intergrated/integrated/

>                         # version here. It is the same as the clang version, and
>                         # it has been already checked by scripts/cc-version.sh.
>
> base-commit: f12b034afeb3a977bbb1c6584dedc0f3dc666f14
> --
> 2.33.0.rc2
>


-- 
Thanks,
~Nick Desaulniers