Re: [FFmpeg-devel] [PATCH] lavc/vp8dsp: R-V V put_bilin_h v unroll

[flow gg <hlefthleft@gmail.com>]

Well.. because scalar registers are limited, the direct unrolling will be
like this for now. We can handle different lengths separately in the future

flow gg <hlefthleft@gmail.com> 于2024年5月30日周四 23:36写道：

> I directly copied the VP9 modifications over... Since len <= 16, it seems
> like it can be improved a bit more
>
> <uk7b@foxmail.com> 于2024年5月30日周四 23:27写道：
>
>> From: sunyuechi <sunyuechi@iscas.ac.cn>
>>
>> Since len < 64, the registers are sufficient, so it can be
>> directly unrolled (a4 is even).
>>
>> Another benefit of unrolling is that it reduces one load operation
>> vertically compared to horizontally.
>>
>>                                  old                 new
>>                              C908   X60          C908   X60
>> vp8_put_bilin4_h_c         :    6.2    5.5     :    6.2    5.5
>> vp8_put_bilin4_h_rvv_i32   :    2.2    2.0     :    1.5    1.5
>> vp8_put_bilin4_v_c         :    6.5    5.7     :    6.2    5.7
>> vp8_put_bilin4_v_rvv_i32   :    2.2    2.0     :    1.2    1.5
>> vp8_put_bilin8_h_c         :   24.2   21.5     :   24.2   21.5
>> vp8_put_bilin8_h_rvv_i32   :    5.2    4.7     :    3.5    3.5
>> vp8_put_bilin8_v_c         :   24.5   21.7     :   24.5   21.7
>> vp8_put_bilin8_v_rvv_i32   :    5.2    4.7     :    3.5    3.2
>> vp8_put_bilin16_h_c        :   48.0   42.7     :   48.0   42.7
>> vp8_put_bilin16_h_rvv_i32  :    5.7    5.0     :    5.2    4.5
>> vp8_put_bilin16_v_c        :   48.2   43.0     :   48.2   42.7
>> vp8_put_bilin16_v_rvv_i32  :    5.7    5.2     :    4.5    4.2
>> ---
>>  libavcodec/riscv/vp8dsp_rvv.S | 34 +++++++++++++++++++++++++++++-----
>>  1 file changed, 29 insertions(+), 5 deletions(-)
>>
>> diff --git a/libavcodec/riscv/vp8dsp_rvv.S b/libavcodec/riscv/vp8dsp_rvv.S
>> index 3360a38cac..5bea6cba9c 100644
>> --- a/libavcodec/riscv/vp8dsp_rvv.S
>> +++ b/libavcodec/riscv/vp8dsp_rvv.S
>> @@ -172,11 +172,35 @@ func ff_put_vp8_bilin4_\type\()_rvv, zve32x
>>          li              t4, 4
>>          sub             t1, t1, \mn
>>  1:
>> -        addi            a4, a4, -1
>> -        bilin_load      v0, \type, \mn
>> -        vse8.v          v0, (a0)
>> -        add             a2, a2, a3
>> -        add             a0, a0, a1
>> +        add             t0, a2, a3
>> +        add             t2, a0, a1
>> +        addi            a4, a4, -2
>> +.ifc \type,v
>> +        add             t3, t0, a3
>> +.else
>> +        addi            t5, a2, 1
>> +        addi            t3, t0, 1
>> +        vle8.v          v2, (t5)
>> +.endif
>> +        vle8.v          v0, (a2)
>> +        vle8.v          v4, (t0)
>> +        vle8.v          v6, (t3)
>> +        vwmulu.vx       v28, v0, t1
>> +        vwmulu.vx       v26, v4, t1
>> +.ifc \type,v
>> +        vwmaccu.vx      v28, \mn, v4
>> +.else
>> +        vwmaccu.vx      v28, \mn, v2
>> +.endif
>> +        vwmaccu.vx      v26, \mn, v6
>> +        vwaddu.wx       v24, v28, t4
>> +        vwaddu.wx       v22, v26, t4
>> +        vnsra.wi        v30, v24, 3
>> +        vnsra.wi        v0, v22, 3
>> +        vse8.v          v30, (a0)
>> +        vse8.v          v0, (t2)
>> +        add             a2, t0, a3
>> +        add             a0, t2, a1
>>          bnez            a4, 1b
>>
>>          ret
>> --
>> 2.45.1
>>
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