Re: [Qemu-ppc] [PATCH v5 2/5] target-ppc: add vector extract instructions

[Richard Henderson]

On 08/31/2016 11:36 PM, Rajalakshmi Srinivasaraghavan wrote:
> +#if defined(HOST_WORDS_BIGENDIAN)
> +#define VEXTRACT(suffix, element)                                            \
> +    void helper_vextract##suffix(ppc_avr_t *r, ppc_avr_t *b, uint32_t index) \
> +    {                                                                        \
> +        r->u64[0] = r->u64[1] = 0;                                           \
> +        memmove(&r->u8[8 - sizeof(r->element)], &b->u8[index],               \
> +               sizeof(r->element[0]));                                       \

Again, you must consider R == B.  I made this same comment wrt v2, when you 
still had a memcpy here.

This is trivial:

  (1) Use memmove to set first sizeof(r->element[0]) bytes,
  (2) Use memset 0 to clean last (16 - sizeof(r->element[0]) bytes.

You have some test cases for these insns, don't you?


r~