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avcodec/aarch64/ac3dsp_neon.S: Optimize ac3_sum_square_butterfly_int32_neon

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Instead of calculating a^2, b^2, (a+b)^2 and (a-b)^2, calculate only
a^2, b^2 and 2*a*b in each iteration and derive the latter parts from
these three at the end.

Before and after:

A78
ac3_sum_square_bufferfly_int32_neon:                   484.8 ( 2.00x)
ac3_sum_square_bufferfly_int32_neon:                   468.2 ( 2.08x)

A72
ac3_sum_square_bufferfly_int32_neon:                   793.6 ( 1.26x)
ac3_sum_square_bufferfly_int32_neon:                   527.3 ( 1.92x)

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Krzysztof Pyrkosz
2025-02-28 22:21:50 +01:00
committed by Martin Storsjö
parent 38929b824b
commit e8d4c55987
1 changed files with 7 additions and 8 deletions
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15
libavcodec/aarch64/ac3dsp_neon.S
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@@ -69,21 +69,20 @@ function ff_ac3_sum_square_butterfly_int32_neon, export=1
movi v0.2d, #0
movi v1.2d, #0
movi v2.2d, #0
movi v3.2d, #0
1: ld1 {v4.2s}, [x1], #8
ld1 {v5.2s}, [x2], #8
add v6.2s, v4.2s, v5.2s
sub v7.2s, v4.2s, v5.2s
smlal v0.2d, v4.2s, v4.2s
smlal v1.2d, v5.2s, v5.2s
smlal v2.2d, v6.2s, v6.2s
smlal v3.2d, v7.2s, v7.2s
subs w3, w3, #2
smlal v0.2d, v4.2s, v4.2s // sum of a^2
smlal v1.2d, v5.2s, v5.2s // sum of b^2
sqdmlal v2.2d, v4.2s, v5.2s // sum of 2ab
b.gt 1b
addp d0, v0.2d
addp d1, v1.2d
addp d2, v2.2d
addp d3, v3.2d
sub d3, d0, d2 // a^2 + b^2 - 2ab
add d2, d0, d2
add d3, d3, d1 // a^2 + b^2 + 2ab
add d2, d2, d1
st1 {v0.1d-v3.1d}, [x0]
ret
endfunc