Re: [Qemu-devel] [PATCH v6 2/4] target/mips: Optimize ILVEV.<B|H|W|D> MSA instructions

[Mateja Marjanovic <Mateja.Marjanovic@rt-rk.com>]

Hello Philippe,
Sorry for replying you so late.

On 4.4.19. 15:42, Philippe Mathieu-Daudé wrote:
> Hi Mateja,
>
> On 4/4/19 3:14 PM, Mateja Marjanovic wrote:
>> From: Mateja Marjanovic <Mateja.Marjanovic@rt-rk.com>
>>
>> Optimize set of MSA instructions ILVEV.<B|H|W|D>, using
>> directly tcg registers and performing logic on them
>> instead of using helpers.
>>
>> In the following table, the first column is the performance
>> before this patch. The second represents the performance,
>> after converting from helpers to tcg, but without using
>> tcg_gen_deposit function. The third one is the solution
>> which is implemented in this patch.
>>
>> Performance measurement is done by executing the
>> instructions a large number of times on a computer
>> with Intel Core i7-3770 CPU @ 3.40GHz×8.
>>
>> ============================================================
>> || instr    ||   before    || no-deposit ||  with-deposit ||
>> ============================================================
>> || ilvev.b  ||  126.92 ms  ||  24.52 ms  ||   24.43 ms    ||
>> || ilvev.h  ||   93.67 ms  ||  23.92 ms  ||   23.86 ms    ||
> I'm quite surprised there is not a single change here since your v5, are
> you sure you used the correct result? I was expecting a slighly improvement.
There is a slight improvement when using tcg constants instead of
int constants variables, but I didn't change the performance table, by
mistake. In v7, it will be more clear.
>
>> || ilvev.w  ||  117.86 ms  ||  23.83 ms  ||   22.17 ms    ||
>> || ilvev.d  ||   45.49 ms  ||  19.74 ms  ||   19.71 ms    ||
>> ============================================================
>>
>> No-deposit column and with-deposit column have the
>> same statistical values in every row, except ILVEV.W,
>> which is the only function which uses the deposit
>> function.
>>
>> No-deposit version of the ILVEV.W implementation:
>>
>> static inline void gen_ilvev_w(CPUMIPSState *env, uint32_t wd,
>>                                 uint32_t ws, uint32_t wt)
>> {
>>      TCGv_i64 t1 = tcg_temp_new_i64();
>>      TCGv_i64 t2 = tcg_temp_new_i64();
>>      uint64_t mask = 0x00000000ffffffffULL;
>>
>>      tcg_gen_andi_i64(t1, msa_wr_d[wt * 2], mask);
>>      tcg_gen_andi_i64(t2, msa_wr_d[ws * 2], mask);
>>      tcg_gen_shli_i64(t2, t2, 32);
>>      tcg_gen_or_i64(msa_wr_d[wd * 2], t1, t2);
>>
>>      tcg_gen_andi_i64(t1, msa_wr_d[wt * 2 + 1], mask);
>>      tcg_gen_andi_i64(t2, msa_wr_d[ws * 2 + 1], mask);
>>      tcg_gen_shli_i64(t2, t2, 32);
>>      tcg_gen_or_i64(msa_wr_d[wd * 2 + 1], t1, t2);
>>
>>      tcg_temp_free_i64(t1);
>>      tcg_temp_free_i64(t2);
>> }
>>
>> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
>> Signed-off-by: Mateja Marjanovic <mateja.marjanovic@rt-rk.com>
>> ---
>>   target/mips/helper.h     |   1 -
>>   target/mips/msa_helper.c |   9 -----
>>   target/mips/translate.c  | 101 ++++++++++++++++++++++++++++++++++++++++++++++-
>>   3 files changed, 100 insertions(+), 11 deletions(-)
>>
>> diff --git a/target/mips/helper.h b/target/mips/helper.h
>> index 02e16c7..82f6a40 100644
>> --- a/target/mips/helper.h
>> +++ b/target/mips/helper.h
>> @@ -864,7 +864,6 @@ DEF_HELPER_5(msa_pckev_df, void, env, i32, i32, i32, i32)
>>   DEF_HELPER_5(msa_pckod_df, void, env, i32, i32, i32, i32)
>>   DEF_HELPER_5(msa_ilvl_df, void, env, i32, i32, i32, i32)
>>   DEF_HELPER_5(msa_ilvr_df, void, env, i32, i32, i32, i32)
>> -DEF_HELPER_5(msa_ilvev_df, void, env, i32, i32, i32, i32)
>>   DEF_HELPER_5(msa_vshf_df, void, env, i32, i32, i32, i32)
>>   DEF_HELPER_5(msa_srar_df, void, env, i32, i32, i32, i32)
>>   DEF_HELPER_5(msa_srlr_df, void, env, i32, i32, i32, i32)
>> diff --git a/target/mips/msa_helper.c b/target/mips/msa_helper.c
>> index a7ea6aa..d5c3842 100644
>> --- a/target/mips/msa_helper.c
>> +++ b/target/mips/msa_helper.c
>> @@ -1197,15 +1197,6 @@ MSA_FN_DF(ilvl_df)
>>       } while (0)
>>   MSA_FN_DF(ilvr_df)
>>   #undef MSA_DO
>> -
>> -#define MSA_DO(DF)                      \
>> -    do {                                \
>> -        pwx->DF[2*i]   = pwt->DF[2*i];  \
>> -        pwx->DF[2*i+1] = pws->DF[2*i];  \
>> -    } while (0)
>> -MSA_FN_DF(ilvev_df)
>> -#undef MSA_DO
>> -
>>   #undef MSA_LOOP_COND
>>   
>>   #define MSA_LOOP_COND(DF) \
>> diff --git a/target/mips/translate.c b/target/mips/translate.c
>> index df685e4..3057669 100644
>> --- a/target/mips/translate.c
>> +++ b/target/mips/translate.c
>> @@ -28973,6 +28973,90 @@ static inline void gen_ilvod_d(CPUMIPSState *env, uint32_t wd,
>>       tcg_gen_mov_i64(msa_wr_d[wd * 2 + 1], msa_wr_d[ws * 2 + 1]);
>>   }
>>   
>> +/*
>> + * [MSA] ILVEV.B wd, ws, wt
>> + *
>> + *   Vector Interleave Even (byte data elements)
>> + *
>> + */
>> +static inline void gen_ilvev_b(CPUMIPSState *env, uint32_t wd,
>> +                               uint32_t ws, uint32_t wt)
>> +{
>> +    TCGv_i64 t1 = tcg_temp_new_i64();
>> +    TCGv_i64 t2 = tcg_temp_new_i64();
>> +    TCGv_i64 mask = tcg_const_i64(0x00ff00ff00ff00ffULL);
>> +
>> +    tcg_gen_and_i64(t1, msa_wr_d[wt * 2], mask);
>> +    tcg_gen_and_i64(t2, msa_wr_d[ws * 2], mask);
>> +    tcg_gen_shli_i64(t2, t2, 8);
>> +    tcg_gen_or_i64(msa_wr_d[wd * 2], t1, t2);
>> +
>> +    tcg_gen_and_i64(t1, msa_wr_d[wt * 2 + 1], mask);
>> +    tcg_gen_and_i64(t2, msa_wr_d[ws * 2 + 1], mask);
>> +    tcg_gen_shli_i64(t2, t2, 8);
>> +    tcg_gen_or_i64(msa_wr_d[wd * 2 + 1], t1, t2);
>> +
>> +    tcg_temp_free_i64(mask);
>> +    tcg_temp_free_i64(t1);
>> +    tcg_temp_free_i64(t2);
>> +}
>> +
>> +/*
>> + * [MSA] ILVEV.H wd, ws, wt
>> + *
>> + *   Vector Interleave Even (halfword data elements)
>> + *
>> + */
>> +static inline void gen_ilvev_h(CPUMIPSState *env, uint32_t wd,
>> +                               uint32_t ws, uint32_t wt)
>> +{
>> +    TCGv_i64 t1 = tcg_temp_new_i64();
>> +    TCGv_i64 t2 = tcg_temp_new_i64();
>> +    TCGv_i64 mask = tcg_const_i64(0x0000ffff0000ffffULL);
>> +
>> +    tcg_gen_and_i64(t1, msa_wr_d[wt * 2], mask);
>> +    tcg_gen_and_i64(t2, msa_wr_d[ws * 2], mask);
>> +    tcg_gen_shli_i64(t2, t2, 16);
>> +    tcg_gen_or_i64(msa_wr_d[wd * 2], t1, t2);
>> +
>> +    tcg_gen_and_i64(t1, msa_wr_d[wt * 2 + 1], mask);
>> +    tcg_gen_and_i64(t2, msa_wr_d[ws * 2 + 1], mask);
>> +    tcg_gen_shli_i64(t2, t2, 16);
>> +    tcg_gen_or_i64(msa_wr_d[wd * 2 + 1], t1, t2);
>> +
>> +    tcg_temp_free_i64(mask);
>> +    tcg_temp_free_i64(t1);
>> +    tcg_temp_free_i64(t2);
>> +}
> Apparently you missed my comment about refactoring using mask/shift as
> arguments:
>
> static inline void gen_ilvev_hb(CPUMIPSState *env, uint32_t wd,
>                                  uint32_t ws, uint32_t wt,
>                                  int64_t mask, int64_t shift)
> {
>      TCGv_i64 t1 = tcg_temp_new_i64();
>      TCGv_i64 t2 = tcg_temp_new_i64();
>      TCGv_i64 tm = tcg_const_i64(mask);
>
>      tcg_gen_and_i64(t1, msa_wr_d[wt * 2], tm);
>      tcg_gen_and_i64(t2, msa_wr_d[ws * 2], tm);
>      tcg_gen_shli_i64(t2, t2, shift);
>      tcg_gen_or_i64(msa_wr_d[wd * 2], t1, t2);
>
>      tcg_gen_and_i64(t1, msa_wr_d[wt * 2 + 1], tm);
>      tcg_gen_and_i64(t2, msa_wr_d[ws * 2 + 1], tm);
>      tcg_gen_shli_i64(t2, t2, shift);
>      tcg_gen_or_i64(msa_wr_d[wd * 2 + 1], t1, t2);
>
>      tcg_temp_free_i64(tm);
>      tcg_temp_free_i64(t1);
>      tcg_temp_free_i64(t2);
> }
>
> static inline void gen_ilvev_b(CPUMIPSState *env, uint32_t wd,
>                                 uint32_t ws, uint32_t wt)
> {
>      gen_ilvev_hb(env, wd, ws, wt, 0x00ff00ff00ff00ffLL, 8);
> }
>
> static inline void gen_ilvev_h(CPUMIPSState *env, uint32_t wd,
>                                 uint32_t ws, uint32_t wt)
> {
>      gen_ilvev_hb(env, wd, ws, wt, 0x0000ffff0000ffffLL, 16);
> }
Yes, I did miss it. I will do what you suggested in v7.
It represents a nice code reorganisation.
>
>
>> +
>> +/*
>> + * [MSA] ILVEV.W wd, ws, wt
>> + *
>> + *   Vector Interleave Even (word data elements)
>> + *
>> + */
>> +static inline void gen_ilvev_w(CPUMIPSState *env, uint32_t wd,
>> +                               uint32_t ws, uint32_t wt)
>> +{
>> +    tcg_gen_deposit_i64(msa_wr_d[wd * 2], msa_wr_d[wt * 2],
>> +                        msa_wr_d[ws * 2], 32, 32);
>> +    tcg_gen_deposit_i64(msa_wr_d[wd * 2 + 1], msa_wr_d[wt * 2 + 1],
>> +                        msa_wr_d[ws * 2 + 1], 32, 32);
>> +}
>> +
>> +/*
>> + * [MSA] ILVEV.D wd, ws, wt
>> + *
>> + *   Vector Interleave Even (Doubleword data elements)
>> + *
>> + */
>> +static inline void gen_ilvev_d(CPUMIPSState *env, uint32_t wd,
>> +                               uint32_t ws, uint32_t wt)
>> +{
>> +    tcg_gen_mov_i64(msa_wr_d[wd * 2 + 1], msa_wr_d[ws * 2]);
>> +    tcg_gen_mov_i64(msa_wr_d[wd * 2], msa_wr_d[wt * 2]);
>> +}
>> +
>>   static void gen_msa_3r(CPUMIPSState *env, DisasContext *ctx)
>>   {
>>   #define MASK_MSA_3R(op)    (MASK_MSA_MINOR(op) | (op & (0x7 << 23)))
>> @@ -29129,7 +29213,22 @@ static void gen_msa_3r(CPUMIPSState *env, DisasContext *ctx)
>>           gen_helper_msa_mod_s_df(cpu_env, tdf, twd, tws, twt);
>>           break;
>>       case OPC_ILVEV_df:
>> -        gen_helper_msa_ilvev_df(cpu_env, tdf, twd, tws, twt);
>> +        switch (df) {
>> +        case DF_BYTE:
>> +            gen_ilvev_b(env, wd, ws, wt);
>> +            break;
>> +        case DF_HALF:
>> +            gen_ilvev_h(env, wd, ws, wt);
>> +            break;
>> +        case DF_WORD:
>> +            gen_ilvev_w(env, wd, ws, wt);
>> +            break;
>> +        case DF_DOUBLE:
>> +            gen_ilvev_d(env, wd, ws, wt);
>> +            break;
>> +        default:
>> +            assert(0);
>> +        }
>>           break;
>>       case OPC_BINSR_df:
>>           gen_helper_msa_binsr_df(cpu_env, tdf, twd, tws, twt);
Thank you for looking so deeply into my code.
Regards,
Mateja