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

[Yongbok Kim <yongbok.kim@imgtec.com>]

On 05/11/2014 17:43, Richard Henderson wrote:
> 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~
Hi Richard,

Agreed. DF is already known in translation time.
I do have a plan to improve efficiency of MSA implementation.

Regards,
Yongbok