linux-kernel - Re: [PATCH] LoongArch: Select ARCH_SUPPORTS_INT128 if CC_HAS

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Message-ID: <CAAhV-H5EZ=7OF7CSiYyZ8_+wWuenpo=K2WT8-6mAT4CvzUC_4g@mail.gmail.com>
Date: Fri, 26 Apr 2024 12:00:12 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Xi Ruoyao <xry111@...111.site>
Cc: WANG Xuerui <kernel@...0n.name>, loongarch@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, Tiezhu Yang <yangtiezhu@...ngson.cn>
Subject: Re: [PATCH] LoongArch: Select ARCH_SUPPORTS_INT128 if CC_HAS_INT128

Hi, Ruoyao,

If enable CONFIG_DEBUG_INFO_BTF, we get:

loongarch64-unknown-linux-gnu-ld: kernel/sched/fair.o: in function
`mul_u64_u32_shr':
/home/chenhuacai/linux-test.git/./include/linux/math64.h:161:(.text+0x5e4):
undefined reference to `__lshrti3'

So, could you please implement _ashlti3(), __ashrti3(), and
__lshrti3() as commit fbac266f095de92b93e7 ("s390: select
ARCH_SUPPORTS_INT128") does?

Huacai

On Thu, Mar 28, 2024 at 1:18 AM Xi Ruoyao <xry111@...111.site> wrote:
>
> This allows compiling a full 128-bit product of two 64-bit integers as
> a mul/mulh pair, instead of a nasty long sequence of 20+ instructions.
>
> Signed-off-by: Xi Ruoyao <xry111@...111.site>
> ---
>  arch/loongarch/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index a5f300ec6f28..5a769bb92d7c 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -56,6 +56,7 @@ config LOONGARCH
>         select ARCH_SUPPORTS_ACPI
>         select ARCH_SUPPORTS_ATOMIC_RMW
>         select ARCH_SUPPORTS_HUGETLBFS
> +       select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
>         select ARCH_SUPPORTS_LTO_CLANG
>         select ARCH_SUPPORTS_LTO_CLANG_THIN
>         select ARCH_SUPPORTS_NUMA_BALANCING
> --
> 2.44.0
>
>