> On Mar 2, 2025, at 05:39, Martin Storsjö <mar...@martin.st> wrote:
>
> On Thu, 20 Feb 2025, Zhao Zhili wrote:
>
>> From: Zhao Zhili <zhiliz...@tencent.com>
>>
>> clang does better than the assembly code before the patch, especially
>> for small size:
>>
>> hevc_idct_4x4_dc_8_c: 11.2 ( 1.00x)
>> hevc_idct_4x4_dc_8_neon: 15.5 ( 0.73x)
>> hevc_idct_4x4_dc_10_c: 12.0 ( 1.00x)
>> hevc_idct_4x4_dc_10_neon: 15.2 ( 0.79x)
>> hevc_idct_8x8_dc_8_c: 13.2 ( 1.00x)
>> hevc_idct_8x8_dc_8_neon: 18.2 ( 0.73x)
>> hevc_idct_8x8_dc_10_c: 13.5 ( 1.00x)
>> hevc_idct_8x8_dc_10_neon: 17.2 ( 0.78x)
>> hevc_idct_16x16_dc_8_c: 41.8 ( 1.00x)
>> hevc_idct_16x16_dc_8_neon: 37.8 ( 1.11x)
>> hevc_idct_16x16_dc_10_c: 41.8 ( 1.00x)
>> hevc_idct_16x16_dc_10_neon: 37.8 ( 1.11x)
>> hevc_idct_32x32_dc_8_c: 130.2 ( 1.00x)
>> hevc_idct_32x32_dc_8_neon: 132.2 ( 0.98x)
>> hevc_idct_32x32_dc_10_c: 130.2 ( 1.00x)
>> hevc_idct_32x32_dc_10_neon: 132.2 ( 0.98x)
>>
>> This patch basically clone what the compiler does, so the performance
>> is the same.
>> ---
>> libavcodec/aarch64/hevcdsp_idct_neon.S | 59 ++++++++++++++------------
>> 1 file changed, 33 insertions(+), 26 deletions(-)
>>
>> diff --git a/libavcodec/aarch64/hevcdsp_idct_neon.S
>> b/libavcodec/aarch64/hevcdsp_idct_neon.S
>> index 3cac6e6db9..4543ab6b07 100644
>> --- a/libavcodec/aarch64/hevcdsp_idct_neon.S
>> +++ b/libavcodec/aarch64/hevcdsp_idct_neon.S
>> @@ -888,38 +888,45 @@ function ff_hevc_transform_luma_4x4_neon_8, export=1
>> ret
>> endfunc
>>
>> +.macro idct_8x8_dc_store offset
>> +.irp i, 0x0, 0x20, 0x40, 0x60
>> + stp q0, q0, [x0, #(\offset + \i)]
>> +.endr
>> +.endm
>> +
>> +.macro idct_16x16_dc_store
>> +.irp index, 0x0, 0x80, 0x100, 0x180
>> + idct_8x8_dc_store offset=\index
>> +.endr
>> +.endm
>> +
>> // void ff_hevc_idct_NxN_dc_DEPTH_neon(int16_t *coeffs)
>> .macro idct_dc size, bitdepth
>> function ff_hevc_idct_\size\()x\size\()_dc_\bitdepth\()_neon, export=1
>> - ld1r {v4.8h}, [x0]
>> - srshr v4.8h, v4.8h, #1
>> - srshr v0.8h, v4.8h, #(14 - \bitdepth)
>> - srshr v1.8h, v4.8h, #(14 - \bitdepth)
>> -.if \size > 4
>> - srshr v2.8h, v4.8h, #(14 - \bitdepth)
>> - srshr v3.8h, v4.8h, #(14 - \bitdepth)
>> -.if \size > 16 /* dc 32x32 */
>> - mov x2, #4
>> + ldrsh w1, [x0]
>> + add w1, w1, #1
>> + asr w1, w1, #1
>> + add w1, w1, #(1 << (13 - \bitdepth))
>> + asr w1, w1, #(14 - \bitdepth)
>> + dup v0.8h, w1
>> +
>> +.if \size < 8
>> + stp q0, q0, [x0]
>> +.else
>> +.if \size < 16
>
> You can use .elseif instead of .else and a nested .if.
Modified locally and pushed, thanks for the review.
>
> Other than that, this patch looks good to me, thanks!
>
> // Martin
>
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