From: Nathan Chancellor <nathan@kernel.org>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com,
Nick Desaulniers <ndesaulniers@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] kbuild: remove LLVM=1 test from HAS_LTO_CLANG
Date: Wed, 3 Mar 2021 16:37:51 -0700 [thread overview]
Message-ID: <20210303233751.k5tkmjdt627oucn3@archlinux-ax161> (raw)
In-Reply-To: <20210303183333.46543-1-masahiroy@kernel.org>
On Thu, Mar 04, 2021 at 03:33:30AM +0900, Masahiro Yamada wrote:
> This guarding is wrong. As Documentation/kbuild/llvm.rst notes, LLVM=1
> switches the default of tools, but you can still override CC, LD, etc.
> individually.
>
> BTW, LLVM is not 1/0 flag. If LLVM is not passed in, it is empty.
>
> Non-zero return code is all treated as failure anyway.
>
> So, $(success,test $(LLVM) -eq 1) and $(success,test "$(LLVM)" = 1)
> works equivalently in the sense that both are expanded to 'n' if LLVM
> is not given. The difference is that the former internally fails due
> to syntax error.
>
> $ test ${LLVM} -eq 1
> bash: test: -eq: unary operator expected
> $ echo $?
> 2
>
> $ test "${LLVM}" -eq 1
> bash: test: : integer expression expected
> $ echo $?
> 2
>
> $ test "${LLVM}" = 1
> echo $?
> 1
>
> $ test -n "${LLVM}"
> $ echo $?
> 1
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Yes, there is not too much point of checking if $(LLVM) is set or not
because we already check for the other tools.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> ---
>
> arch/Kconfig | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 2bb30673d8e6..2af10ebe5ed0 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -632,7 +632,6 @@ config HAS_LTO_CLANG
> def_bool y
> # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510
> depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD
> - depends on $(success,test $(LLVM) -eq 1)
> depends on $(success,test $(LLVM_IAS) -eq 1)
> depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
> depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
> --
> 2.27.0
>
prev parent reply other threads:[~2021-03-04 1:02 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-03 18:33 [PATCH 1/4] kbuild: remove LLVM=1 test from HAS_LTO_CLANG Masahiro Yamada
2021-03-03 18:33 ` [PATCH 2/4] kbuild: collect minimum tool versions into scripts/tool-version.sh Masahiro Yamada
2021-03-04 0:11 ` Nathan Chancellor
2021-03-05 6:40 ` Masahiro Yamada
2021-03-12 17:21 ` Masahiro Yamada
2021-03-04 22:10 ` Nicolas Pitre
2021-03-05 6:41 ` Masahiro Yamada
2021-03-03 18:33 ` [PATCH 3/4] kbuild: check the minimum assembler version in Kconfig Masahiro Yamada
2021-03-04 0:28 ` Nathan Chancellor
2021-03-05 1:25 ` Nick Desaulniers
2021-03-05 17:48 ` Masahiro Yamada
2021-03-07 4:42 ` Nathan Chancellor
2021-03-03 18:33 ` [PATCH 4/4] kbuild: dwarf: use AS_VERSION instead of test_dwarf5_support.sh Masahiro Yamada
2021-03-03 20:44 ` Nick Desaulniers
2021-03-12 17:18 ` Masahiro Yamada
2021-03-04 0:30 ` Nathan Chancellor
2021-03-03 20:47 ` [PATCH 1/4] kbuild: remove LLVM=1 test from HAS_LTO_CLANG Nick Desaulniers
2021-03-05 6:06 ` Masahiro Yamada
2021-03-08 19:11 ` Sami Tolvanen
2021-03-03 23:37 ` Nathan Chancellor [this message]
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