[PATCH] LoongArch: Select ARCH_HAS_FAST_MULTIPLIER

[PATCH] LoongArch: Select ARCH_HAS_FAST_MULTIPLIER

[Xi Ruoyao]

LA464 and LA664 can do 32-bit/64-bit integer multiplication with a
latency of 4 cycles and a throughput of 2 ops per cycle.  It's
comparable to mainstream x86 and arm64 cores, so select
ARCH_HAS_FAST_MULTIPLIER like them.

It speeds up __sw_hweight32 in lib/hweight.c for about 14% on LA464 and
11% on LA664, and __sw_hweight64 for about 30% on LA464 and 33% on
LA664.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
---
 arch/loongarch/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 5a769bb92d7c..d52a95195e7f 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -16,6 +16,7 @@ config LOONGARCH
 	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
 	select ARCH_HAS_CPU_FINALIZE_INIT
 	select ARCH_HAS_CURRENT_STACK_POINTER
+	select ARCH_HAS_FAST_MULTIPLIER
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
-- 
2.44.0

Re: [PATCH] LoongArch: Select ARCH_HAS_FAST_MULTIPLIER

[Huacai Chen]

Queued for loongarch-next, thanks.

Huacai

On Thu, Mar 28, 2024 at 1:18 AM Xi Ruoyao <xry111@xry111.site> wrote:
>
> LA464 and LA664 can do 32-bit/64-bit integer multiplication with a
> latency of 4 cycles and a throughput of 2 ops per cycle.  It's
> comparable to mainstream x86 and arm64 cores, so select
> ARCH_HAS_FAST_MULTIPLIER like them.
>
> It speeds up __sw_hweight32 in lib/hweight.c for about 14% on LA464 and
> 11% on LA664, and __sw_hweight64 for about 30% on LA464 and 33% on
> LA664.
>
> Signed-off-by: Xi Ruoyao <xry111@xry111.site>
> ---
>  arch/loongarch/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 5a769bb92d7c..d52a95195e7f 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -16,6 +16,7 @@ config LOONGARCH
>         select ARCH_HAS_ACPI_TABLE_UPGRADE      if ACPI
>         select ARCH_HAS_CPU_FINALIZE_INIT
>         select ARCH_HAS_CURRENT_STACK_POINTER
> +       select ARCH_HAS_FAST_MULTIPLIER
>         select ARCH_HAS_FORTIFY_SOURCE
>         select ARCH_HAS_KCOV
>         select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
> --
> 2.44.0
>