Re: [PATCH 07/20] target/loongarch: Add fixed point arithmetic instruction translation

[Song Gao <gaosong@loongson.cn>]

Hi, Philippe,

On 07/02/2021 04:51 PM, Philippe Mathieu-Daudé wrote:
> On 7/2/21 10:15 AM, Song Gao wrote:
>> On 07/02/2021 04:31 AM, Philippe Mathieu-Daudé wrote:
>>> On 6/28/21 2:04 PM, Song Gao wrote:
>>>> This patch implement fixed point arithemtic instruction translation.
>>>>
>>>> This includes:
>>>> - ADD.{W/D}, SUB.{W/D}
>>>> - ADDI.{W/D}, ADDU16ID
>>>> - ALSL.{W[U]/D}
>>>> - LU12I.W, LU32I.D LU52I.D
>>>> - SLT[U], SLT[U]I
>>>> - PCADDI, PCADDU12I, PCADDU18I, PCALAU12I
>>>> - AND, OR, NOR, XOR, ANDN, ORN
>>>> - MUL.{W/D}, MULH.{W[U]/D[U]}
>>>> - MULW.D.W[U]
>>>> - DIV.{W[U]/D[U]}, MOD.{W[U]/D[U]}
>>>> - ANDI, ORI, XORI
>>>>
>>>> Signed-off-by: Song Gao <gaosong@loongson.cn>
>>>> ---
>>>>  target/loongarch/insns.decode |  89 ++++++++
>>>>  target/loongarch/instmap.h    |  53 +++++
>>>>  target/loongarch/trans.inc.c  | 367 +++++++++++++++++++++++++++++++++
>>>>  target/loongarch/translate.c  | 458 ++++++++++++++++++++++++++++++++++++++++++
>>>>  4 files changed, 967 insertions(+)
>>>>  create mode 100644 target/loongarch/insns.decode
>>>>  create mode 100644 target/loongarch/instmap.h
>>>>  create mode 100644 target/loongarch/trans.inc.c
> 
>>> It seems you are missing what decodetree is for... You should inline
>>> each opcode code from gen_loongarch_muldiv in the opcode handler.
>>>
>>> Don't take MIPS as an example =)
>>>
>> Hi, Philippe,
>>
>> I‘m not sure I understand right.  Here is an example of my modification
>>
>>     static bool trans_xxx(DisasContext *ctx, arg_mul_w *a)
>>     {
>>         gen_loongarch_muldiv(ctx, a->rd, a->rj, a->rk);
>>         return true;
>>     }
>>     ...
>>
>>     static void gen_loongarch_muldiv(DisasContext *ctx, int rd,
>>                                      int rj, int rk)
>>     {
>>         TCGv t0, t1;
>>
>>         if (rd == 0) {
>>             /* Treat as NOP. */
>>             return;
>>         }
>>
>>         t0 = tcg_temp_new();
>>         t1 = tcg_temp_new();
>>
>>         gen_load_gpr(t0, rj);
>>         gen_load_gpr(t1, rk);
>>
>>         switch (ctx->opcode) {
>>         case  xxx_opcode:
>>              /* translate  xxx  */
>>         ...
>>
>>     }
>>
>> Is that right？
> 
> No. With decode"tree" you only have to implement the
> decode"leaves". No need to pass 'uin32_t opcode' and
> use 'switch (ctx->opcode) ...'. Example for LA_OPC_MUL_D:
> 
> static bool trans_mul_d(DisasContext *ctx, int rd, int rj, int rk)
> {
>     TCGv t0, t1;
> 
>     check_loongarch_64(ctx);
> 
>     if (a->rd == 0) {
>         /* Treat as NOP. */
>         return true;
>     }
> 
>     t0 = tcg_temp_new();
>     t1 = tcg_temp_new();
> 
>     gen_load_gpr(t0, a->rj);
>     gen_load_gpr(t1, a->rk);
> 
>     tcg_gen_mul_i64(cpu_gpr[a->rd], t0, t1);
> 
>     tcg_temp_free(t0);
>     tcg_temp_free(t1);
> 
>     return true;
> }
> 

Got it, thanks for kindly help!

Regards
Song Gao