Re: [PATCH 17/33] target/mips: Convert MSA FILL opcode to decodetree

[Philippe Mathieu-Daudé]

On 10/24/21 19:26, Richard Henderson wrote:
> On 10/24/21 9:44 AM, Philippe Mathieu-Daudé wrote:
>> On 10/24/21 07:04, Richard Henderson wrote:
>>> On 10/23/21 2:47 PM, Philippe Mathieu-Daudé wrote:
>>>> Convert the FILL opcode (Vector Fill from GPR) to decodetree.
>>>>
>>>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>>>> ---
>>>>    target/mips/tcg/msa.decode      |  2 ++
>>>>    target/mips/tcg/msa_translate.c | 40
>>>> +++++++++++++++++++++++----------
>>>>    2 files changed, 30 insertions(+), 12 deletions(-)
>>
>>>>    +static bool trans_FILL(DisasContext *ctx, arg_msa_r *a)
>>>> +{
>>>> +    TCGv_i32 twd;
>>>> +    TCGv_i32 tws;
>>>> +    TCGv_i32 tdf;
>>>> +
>>>> +    if (!check_msa_access(ctx)) {
>>>> +        return false;
>>>> +    }
>>>> +
>>>> +    if (TARGET_LONG_BITS != 64 && a->df == DF_DOUBLE) {
>>>> +        /* Double format valid only for MIPS64 */
>>>> +        gen_reserved_instruction(ctx);
>>>> +        return true;
>>>> +    }
>>>
>>> I expect this reserved check should be above the MSA is disabled check,
>>> within check_msa_access.
>>>
>>>> +    twd = tcg_const_i32(a->wd);
>>>> +    tws = tcg_const_i32(a->ws);
>>>
>>> tcg_constant_i32.
>>
>> Hmm I am confused here, only 'df' is constant, 'ws' is GPR[$rs].
>> Since it is limited in [0,32[ and used read-only by the helper,
>> we can also pass it as constant?
> 
> What?  You're passing the constant ws to the helper, not the contents of
> the gpr -- that's what the helper is expecting.

OK got it now, thanks :)