Re: [PATCH v4 07/11] xen/arm: bitops: Implement a ffsll function

[Stefano Stabellini <sstabellini@kernel.org>]

On Fri, 8 Jan 2021, Rahul Singh wrote:
> Implement the ffsll based on built-in function "__builtin_ffsll()"
> 
> ffsll will return one plus the index of the least significant 1-bit in
> doublewords or if doublewords is zero, returns zero.
> 
> Signed-off-by: Rahul Singh <rahul.singh@arm.com>
> ---
> Changes in V4:
>  - This patch is introduce in this verison.
> ---
>  xen/include/asm-arm/bitops.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/xen/include/asm-arm/bitops.h b/xen/include/asm-arm/bitops.h
> index 71ae14cab3..7f83ee1828 100644
> --- a/xen/include/asm-arm/bitops.h
> +++ b/xen/include/asm-arm/bitops.h
> @@ -170,6 +170,18 @@ static inline unsigned int find_first_set_bit(unsigned long word)
>          return ffsl(word) - 1;
>  }
>  
> +/**
> + * ffsll - find the first least significant set bit
> + * @doubleword: double word to search
> + *
> + * Returns one plus the index of the least significant 1-bit in @doubleword
> + * or if doubleword is zero, returns zero.
> + */
> +static inline int ffsll(long long doubleword)
> +{
> +        return __builtin_ffsll(doubleword);
> +}

This compiles fine with my old 4.9 compiler and in gitlab too, so I am
OK with this, even better because it is less code to maintain.

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>