Re: [Qemu-devel] [PATCH v3 36/38] target-microblaze: Use tcg_gen_movcond in eval_cond_jmp

[Philippe Mathieu-Daudé]

Hi Edgar,

On 05/17/2018 11:22 AM, Philippe Mathieu-Daudé wrote:
> On 05/16/2018 03:51 PM, Edgar E. Iglesias wrote:
>> From: "Edgar E. Iglesias" <address@hidden>
>>
>> Cleanup eval_cond_jmp to use tcg_gen_movcond_i64().
>> No functional change.
>>
>> Suggested-by: Richard Henderson <address@hidden>
>> Signed-off-by: Edgar E. Iglesias <address@hidden>
>> ---
>>  target/microblaze/translate.c | 16 ++++++++++------
>>  1 file changed, 10 insertions(+), 6 deletions(-)
>>
>> diff --git a/target/microblaze/translate.c b/target/microblaze/translate.c
>> index a846797d9c..78c2855ff0 100644
>> --- a/target/microblaze/translate.c
>> +++ b/target/microblaze/translate.c
>> @@ -1171,12 +1171,16 @@ static inline void eval_cc(DisasContext *dc, 
>> unsigned int cc,
>>  
>>  static void eval_cond_jmp(DisasContext *dc, TCGv_i64 pc_true, TCGv_i64 
>> pc_false)
>>  {
>> -    TCGLabel *l1 = gen_new_label();
>> -    /* Conditional jmp.  */
>> -    tcg_gen_mov_i64(cpu_SR[SR_PC], pc_false);
>> -    tcg_gen_brcondi_i32(TCG_COND_EQ, env_btaken, 0, l1);
>> -    tcg_gen_mov_i64(cpu_SR[SR_PC], pc_true);
>> -    gen_set_label(l1);
>> +    TCGv_i64 tmp_btaken = tcg_temp_new_i64();
>> +    TCGv_i64 tmp_zero = tcg_const_i64(0);

Why not use cpu_R[0] directly?

I wonder, maybe the current model doesn't not have R0 hardwired to 0?

>> +
>> +    tcg_gen_extu_i32_i64(tmp_btaken, env_btaken);
> 
> env_btaken is i32, ok.
> 
> Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> 
>> +    tcg_gen_movcond_i64(TCG_COND_NE, cpu_SR[SR_PC],
>> +                        tmp_btaken, tmp_zero,
>> +                        pc_true, pc_false);

So we could drop a temp, using:

        tcg_gen_movcond_i64(TCG_COND_NE, cpu_SR[SR_PC],
                            tmp_btaken, cpu_R[0],
                            pc_true, pc_false);

>> +
>> +    tcg_temp_free_i64(tmp_btaken);
>> +    tcg_temp_free_i64(tmp_zero);
>>  }
>>  
>>  static void dec_bcc(DisasContext *dc)
>>