Re: [Qemu-ppc] [PATCH v1 1/5] target-ppc: add vector insert instructions

[Richard Henderson]

On 08/04/2016 06:33 PM, Rajalakshmi Srinivasaraghavan wrote:
> +#if defined(HOST_WORDS_BIGENDIAN)
> +#define VINSERT(suffix, element, index)                                     \
> +    void helper_vinsert##suffix(ppc_avr_t *r, ppc_avr_t *b, uint32_t splat) \
> +    {                                                                       \
> +        memcpy(&r->u8[SPLAT_ELEMENT(u8)], &b->element[index],               \
> +               sizeof(r->element[0]));                                      \
> +    }
> +#else
> +#define VINSERT(suffix, element, index)                                     \
> +    void helper_vinsert##suffix(ppc_avr_t *r, ppc_avr_t *b, uint32_t splat) \
> +    {                                                                       \
> +        memcpy(&r->u8[(16 - splat) - sizeof(r->element[0])],                \
> +               &b->element[(ARRAY_SIZE(r->element) - index) - 1],           \
> +               sizeof(r->element[0]));                                      \
> +    }

Something somewhere needs to check for out of bounds SPLAT, for evil guests.

The spec says it's undefined; I don't recall if that gives you the latitude to 
generate an illegal instruction trap during translate.


r~