Re: [PATCH for-5.0, v1] target/mips: Fix loongson multimedia condition instructions

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 3/30/20 6:18 PM, Jiaxun Yang wrote:
> 
> 
> 于 2020年3月30日 GMT+08:00 下午11:39:44, "Philippe Mathieu-Daudé" <philmd@redhat.com> 写到:
>> Hi Jiaxun Yang,
>>
>> On 3/24/20 1:22 PM, Jiaxun Yang wrote:
>>> Loongson multimedia condition instructions were previously
>> implemented as
>>> write 0 to rd due to lack of documentation. So I just confirmed with
>> Loongson
>>> about their encoding and implemented them correctly.
>>
>> If you have a binary using loongson multimedia instructions, can you
>> add
>> a test? So this code won't bitrot.
> 
> I know ffmpeg uses it.
> But I think that's too fat.

Looks perfect to me!

It'll be simpler if you use a pre-build binary from a known distribution.

> 
>>
>> I'm in particular interested by a test covering the MAC2008
>> instructions. You can look at examples in the tests/tcg/mips/
>> directory,
>> Aleksandar added a lot of tests there.
> 
> I'm going to try that.
> 
> Thanks.
> 
>>
>> Thanks,
>>
>> Phil.
>>
>>>
>>> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
>>> Acked-by: Huacai Chen <chenhc@lemote.com>
>>> ---
>>> v1: Use deposit opreations according to Richard's suggestion.
>>> ---
>>>    target/mips/translate.c | 35 +++++++++++++++++++++++++++++++----
>>>    1 file changed, 31 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/target/mips/translate.c b/target/mips/translate.c
>>> index d745bd2803..25b595a17d 100644
>>> --- a/target/mips/translate.c
>>> +++ b/target/mips/translate.c
>>> @@ -5529,6 +5529,7 @@ static void
>> gen_loongson_multimedia(DisasContext *ctx, int rd, int rs, int rt)
>>>    {
>>>        uint32_t opc, shift_max;
>>>        TCGv_i64 t0, t1;
>>> +    TCGCond cond;
>>>    
>>>        opc = MASK_LMI(ctx->opcode);
>>>        switch (opc) {
>>> @@ -5862,14 +5863,39 @@ static void
>> gen_loongson_multimedia(DisasContext *ctx, int rd, int rs, int rt)
>>>    
>>>        case OPC_SEQU_CP2:
>>>        case OPC_SEQ_CP2:
>>> +        cond = TCG_COND_EQ;
>>> +        goto do_cc_cond;
>>> +        break;
>>>        case OPC_SLTU_CP2:
>>> +        cond = TCG_COND_LTU;
>>> +        goto do_cc_cond;
>>> +        break;
>>>        case OPC_SLT_CP2:
>>> +        cond = TCG_COND_LT;
>>> +        goto do_cc_cond;
>>> +        break;
>>>        case OPC_SLEU_CP2:
>>> +        cond = TCG_COND_LEU;
>>> +        goto do_cc_cond;
>>> +        break;
>>>        case OPC_SLE_CP2:
>>> -        /*
>>> -         * ??? Document is unclear: Set FCC[CC].  Does that mean the
>>> -         * FD field is the CC field?
>>> -         */
>>> +        cond = TCG_COND_LE;
>>> +    do_cc_cond:
>>> +        {
>>> +            int cc = (ctx->opcode >> 8) & 0x7;
>>> +            TCGv_i64 t64 = tcg_temp_new_i64();
>>> +            TCGv_i32 t32 = tcg_temp_new_i32();
>>> +
>>> +            tcg_gen_setcond_i64(cond, t64, t0, t1);
>>> +            tcg_gen_extrl_i64_i32(t32, t64);
>>> +            tcg_gen_deposit_i32(fpu_fcr31, fpu_fcr31, t32,
>>> +                                get_fp_bit(cc), 1);
>>> +
>>> +            tcg_temp_free_i32(t32);
>>> +            tcg_temp_free_i64(t64);
>>> +        }
>>> +        goto no_rd;
>>> +        break;
>>>        default:
>>>            MIPS_INVAL("loongson_cp2");
>>>            generate_exception_end(ctx, EXCP_RI);
>>> @@ -5878,6 +5904,7 @@ static void
>> gen_loongson_multimedia(DisasContext *ctx, int rd, int rs, int rt)
>>>    
>>>        gen_store_fpr64(ctx, t0, rd);
>>>    
>>> +no_rd:
>>>        tcg_temp_free_i64(t0);
>>>        tcg_temp_free_i64(t1);
>>>    }
>>>
>