Re: [PATCH 2/2] util: add util function buffer_zero_avx512()

[Richard Henderson]

On 2/23/20 11:07 PM, Robert Hoo wrote:
> Inspired by your suggestion, I'm thinking go further: use immediate
> rather than a global variable, so that saves 1 memory(/cache) access. 
> 
> #ifdef CONFIG_AVX512F_OPT   
> #define OPTIMIZE_LEN    256
> #else
> #define OPTIMIZE_LEN    64
> #endif

With that, the testing in tests/test-bufferiszero.c, looping through the
implementations, is invalidated.  Because once you start compiling for avx512,
you're no longer testing sse2 et al with the same inputs.

IF we want to change the length to suit avx512, we would want to change it
unconditionally.  And then you could also tidy up avx2 to avoid the extra
comparisons there.


r~