Re: [Qemu-devel] [PATCH v2 5/6] target-ppc: add vprtyb[w/d/q] instructions

[Richard Henderson]

On 10/27/2016 01:36 AM, Nikunj A Dadhania wrote:
> Right, it does reduce number of operations:
>
> +#define SIZE_MASK(x) ((1ULL << (x)) - 1)
> +static uint64_t vparity(uint64_t f1, uint64_t f2, int size)
> +{
> +    uint64_t res = f1 ^ f2;
> +    if (size == 8) return res;
> +    return vparity(res & SIZE_MASK(size/2), res >> (size/2), size/2);
> +}

Why are you using recursion for something that should be 5 operations?  You're 
making this more complicated than it needs to be.

  uint64_t res = b->u64[0] ^ b->u64[1];
  res ^= res >> 32;
  res ^= res >> 16;
  res ^= res >> 8;
  r->u64[LO_IDX] = res & 1;


r~