Re: [PATCH v2 1/2] kbuild: replace AS=clang with LLVM_IA=1

[Nick Desaulniers]

On Tue, Apr 7, 2020 at 11:44 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
>
> The 'AS' variable is unused for building the kernel. Only the remaining
> usage is to turn on the integrated assembler. A boolean flag is a better
> fit for this purpose.
>
> AS=clang was added for experts. So, I replaced it with LLVM_IA=1,
> breaking the backward compatibility.
>
> Suggested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>

Thank you for this series!
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>

> ---
>
> Changes in v2:
>   - new patch
>
>  Documentation/kbuild/llvm.rst | 5 ++++-
>  Makefile                      | 2 +-
>  2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst
> index eefbdfa3e4d9..2b40afa58049 100644
> --- a/Documentation/kbuild/llvm.rst
> +++ b/Documentation/kbuild/llvm.rst
> @@ -50,11 +50,14 @@ LLVM Utilities
>  LLVM has substitutes for GNU binutils utilities. These can be invoked as
>  additional parameters to `make`.
>
> -       make CC=clang AS=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \\
> +       make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \\
>           OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump OBJSIZE=llvm-size \\
>           READELF=llvm-readelf HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar \\
>           HOSTLD=ld.lld
>
> +Currently, the integrated assembler is disabled by default. You can pass
> +LLVM_IA=1 to enable it.
> +
>  Getting Help
>  ------------
>
> diff --git a/Makefile b/Makefile
> index 1b2691057cb5..f9beb696d6d3 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -538,7 +538,7 @@ endif
>  ifneq ($(GCC_TOOLCHAIN),)
>  CLANG_FLAGS    += --gcc-toolchain=$(GCC_TOOLCHAIN)
>  endif
> -ifeq ($(if $(AS),$(shell $(AS) --version 2>&1 | head -n 1 | grep clang)),)
> +ifneq ($(LLVM_IA),1)
>  CLANG_FLAGS    += -no-integrated-as
>  endif
>  CLANG_FLAGS    += -Werror=unknown-warning-option
> --
> 2.17.1
>
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-- 
Thanks,
~Nick Desaulniers