Re: [Qemu-devel] [PATCH v2 10/20] target-mips: add MSA I8 format instructions

[Richard Henderson <rth@twiddle.net>]

On 10/29/2014 02:41 AM, Yongbok Kim wrote:
> +void helper_msa_shf_df(CPUMIPSState *env, uint32_t df, uint32_t wd,
> +                       uint32_t ws, uint32_t imm)
> +{
> +    wr_t *pwd = &(env->active_fpu.fpr[wd].wr);
> +    wr_t *pws = &(env->active_fpu.fpr[ws].wr);
> +    wr_t wx, *pwx = &wx;
> +    uint32_t i;
> +
> +    switch (df) {
> +    case DF_BYTE:
> +        for (i = 0; i < DF_ELEMENTS(DF_BYTE); i++) {
> +            pwx->b[i] = pws->b[SHF_POS(i, imm)];
> +        }
> +        break;
> +    case DF_HALF:
> +        for (i = 0; i < DF_ELEMENTS(DF_HALF); i++) {
> +            pwx->h[i] = pws->h[SHF_POS(i, imm)];
> +        }
> +        break;

Why pass DF to decode at runtime?  It's better to fully decode this at
translate time and call the correct function.


r~