Re: [PATCH v2 2/3] word-at-a-time.h: support zero_bytemask() on alpha and tile

From: Ingo Molnar
Date: Wed Oct 07 2015 - 01:53:26 EST



* Chris Metcalf <cmetcalf@xxxxxxxxxx> wrote:

> Both alpha and tile needed implementations of zero_bytemask.
>
> The alpha version is untested.
>
> Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
> ---
> arch/alpha/include/asm/word-at-a-time.h | 2 ++
> arch/tile/include/asm/word-at-a-time.h | 8 +++++++-
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/alpha/include/asm/word-at-a-time.h b/arch/alpha/include/asm/word-at-a-time.h
> index 6b340d0f1521..902e6ab00a06 100644
> --- a/arch/alpha/include/asm/word-at-a-time.h
> +++ b/arch/alpha/include/asm/word-at-a-time.h
> @@ -52,4 +52,6 @@ static inline unsigned long find_zero(unsigned long bits)
> #endif
> }
>
> +#define zero_bytemask(mask) ((2ul << (find_zero(mask) * 8)) - 1)

Small nit: please use a proper C inline function instead of CPP, as for example
the PowerPC zero_bytemask() function is.

> -/* Generate 0x01 byte values for non-zero bytes using a SIMD instruction. */
> +/* Generate 0x01 byte values for zero bytes using a SIMD instruction. */
> static inline unsigned long has_zero(unsigned long val, unsigned long *data,
> const struct word_at_a_time *c)
> {
> @@ -33,4 +33,10 @@ static inline long find_zero(unsigned long mask)
> #endif
> }
>
> +#ifdef __BIG_ENDIAN
> +#define zero_bytemask(mask) (~1ul << (63 - __builtin_clzl(mask)))
> +#else
> +#define zero_bytemask(mask) ((2ul << __builtin_ctzl(mask)) - 1)
> +#endif

Ditto.

Other than that, for the whole series:

Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>

Thanks,

Ingo
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