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

[Philippe Mathieu-Daudé]

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?