From: Nathan Chancellor <nathan@kernel.org>
To: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Huacai Chen <chenhuacai@kernel.org>,
Miguel Ojeda <ojeda@kernel.org>, WANG Rui <wangrui@loongson.cn>,
rust-for-linux@vger.kernel.org, loongarch@lists.linux.dev,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH v1 1/2] LoongArch: Make LTO case independent in Makefile
Date: Fri, 19 Sep 2025 23:15:36 -0700 [thread overview]
Message-ID: <20250920061536.GA1460394@ax162> (raw)
In-Reply-To: <20250909092707.3127-2-yangtiezhu@loongson.cn>
Hi Tiezhu,
On Tue, Sep 09, 2025 at 05:27:06PM +0800, Tiezhu Yang wrote:
> LTO is not only used for Clang, it maybe used for Rust, make LTO case out
> of CONFIG_CC_HAS_ANNOTATE_TABLEJUMP in Makefile.
>
> This is preparation for later patch, no function changes.
>
> Suggested-by: WANG Rui <wangrui@loongson.cn>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
> arch/loongarch/Makefile | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index a3a9759414f4..9d80af7f75c8 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -102,16 +102,16 @@ KBUILD_CFLAGS += $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)
>
> ifdef CONFIG_OBJTOOL
> ifdef CONFIG_CC_HAS_ANNOTATE_TABLEJUMP
> +KBUILD_CFLAGS += -mannotate-tablejump
> +else
> +KBUILD_CFLAGS += -fno-jump-tables # keep compatibility with older compilers
> +endif
> +ifdef CONFIG_LTO_CLANG
> # The annotate-tablejump option can not be passed to LLVM backend when LTO is enabled.
> # Ensure it is aware of linker with LTO, '--loongarch-annotate-tablejump' also needs to
> # be passed via '-mllvm' to ld.lld.
> -KBUILD_CFLAGS += -mannotate-tablejump
> -ifdef CONFIG_LTO_CLANG
> KBUILD_LDFLAGS += -mllvm --loongarch-annotate-tablejump
> endif
> -else
> -KBUILD_CFLAGS += -fno-jump-tables # keep compatibility with older compilers
> -endif
> endif
>
> KBUILD_RUSTFLAGS += --target=loongarch64-unknown-none-softfloat -Ccode-model=small
> --
> 2.42.0
>
This change is now in -next as commit b15212824a01 ("LoongArch: Make LTO
case independent in Makefile"), where it breaks the build for clang-18,
as '--loongarch-annotate-tablejump' is unimplemented there but there is
no version check before using it.
$ make -skj"$(nproc)" ARCH=loongarch LLVM=1 mrproper defconfig
$ scripts/config -d LTO_NONE -e LTO_CLANG_THIN
$ make -skj"$(nproc)" ARCH=loongarch LLVM=1 olddefconfig vmlinuz.efi
ld.lld: error: -mllvm: ld.lld: Unknown command line argument '--loongarch-annotate-tablejump'.
...
$ scripts/config -s CC_HAS_ANNOTATE_TABLEJUMP
undef
Cheers,
Nathan
next parent reply other threads:[~2025-09-20 6:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20250909092707.3127-1-yangtiezhu@loongson.cn>
[not found] ` <20250909092707.3127-2-yangtiezhu@loongson.cn>
2025-09-20 6:15 ` Nathan Chancellor [this message]
2025-09-20 8:23 ` [PATCH v1 1/2] LoongArch: Make LTO case independent in Makefile Huacai Chen
2025-09-20 9:19 ` Tiezhu Yang
2025-09-20 10:22 ` Tiezhu Yang
2025-09-20 11:41 ` Huacai Chen
2025-09-20 12:52 ` Tiezhu Yang
2025-09-23 1:10 ` Nathan Chancellor
2025-09-23 3:13 ` Tiezhu Yang
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