Subject: Re: [PATCH V2 04/19] math64: Tidy mul_u64_u32_shr()

From: Peter Zijlstra <[email-masked]>
Date: Wed, 24 Apr 2024 17:11:33 +0200

On Mon, Mar 25, 2024 at 08:40:08AM +0200, Adrian Hunter wrote:
> Put together declaration and initialization of local variables.
> 
> Suggested-by: Thomas Gleixner <[email-masked]>
> Signed-off-by: Adrian Hunter <[email-masked]>
> ---

Nothing wrong with this patch, but it is highly unlikely this code is
actually tested much. Most (sane) architectures will use the __int128
version.

>  include/linux/math64.h | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/include/linux/math64.h b/include/linux/math64.h
> index bf74478926d4..fd13622b2056 100644
> --- a/include/linux/math64.h
> +++ b/include/linux/math64.h
> @@ -179,16 +179,12 @@ static __always_inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
>  #ifndef mul_u64_u32_shr
>  static __always_inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
>  {
> -	u32 ah, al;
> +	u32 ah = a >> 32, al = a;
>  	u64 ret;
>  
> -	al = a;
> -	ah = a >> 32;
> -
>  	ret = mul_u32_u32(al, mul) >> shift;
>  	if (ah)
>  		ret += mul_u32_u32(ah, mul) << (32 - shift);
> -
>  	return ret;
>  }
>  #endif /* mul_u64_u32_shr */
> -- 
> 2.34.1
>