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swscale: aarch64: Optimize the final summation in the hscale routine 

Before:                     Cortex A53      A72      A73  Graviton 2  Graviton 3
hscale_8_to_15_width8_neon:     8273.0   4602.5   4289.5      2429.7      1629.1
hscale_8_to_15_width16_neon:   12405.7   6803.0   6359.0      3549.0      2378.4
hscale_8_to_15_width32_neon:   21258.7  11491.7  11469.2      5797.2      3919.6
hscale_8_to_15_width40_neon:   25652.0  14173.7  12488.2      6893.5      4810.4

After:
hscale_8_to_15_width8_neon:     7633.0   3981.5   3350.2      1980.7      1261.1
hscale_8_to_15_width16_neon:   11666.7   5951.0   5512.0      3080.7      2131.4
hscale_8_to_15_width32_neon:   20900.7  10733.2   9481.7      5275.2      3862.1
hscale_8_to_15_width40_neon:   24826.0  13536.2  11502.0      6397.2      4731.9

Thus, this gives overall a 8-29% speedup for the smaller filter
sizes, around 1-8% for the larger filter sizes.

Inspired by a patch by Jonathan Swinney <jswinney@amazon.com>.

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Martin Storsjö 2022-04-20 11:21:28 +03:00
parent d1a44f261a
commit 70db14376c
1 changed files with 3 additions and 11 deletions
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14
libswscale/aarch64/hscale.S
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@ -61,17 +61,9 @@ function ff_hscale_8_to_15_neon, export=1
smlal v3.4S, v18.4H, v19.4H // v3 accumulates srcp[filterPos[3] + {0..3}] * filter[{0..3}]
smlal2 v3.4S, v18.8H, v19.8H // v3 accumulates srcp[filterPos[3] + {4..7}] * filter[{4..7}]
b.gt 2b // inner loop if filterSize not consumed completely
addp v0.4S, v0.4S, v0.4S // part0 horizontal pair adding
addp v1.4S, v1.4S, v1.4S // part1 horizontal pair adding
addp v2.4S, v2.4S, v2.4S // part2 horizontal pair adding
addp v3.4S, v3.4S, v3.4S // part3 horizontal pair adding
addp v0.4S, v0.4S, v0.4S // part0 horizontal pair adding
addp v1.4S, v1.4S, v1.4S // part1 horizontal pair adding
addp v2.4S, v2.4S, v2.4S // part2 horizontal pair adding
addp v3.4S, v3.4S, v3.4S // part3 horizontal pair adding
zip1 v0.4S, v0.4S, v1.4S // part01 = zip values from part0 and part1
zip1 v2.4S, v2.4S, v3.4S // part23 = zip values from part2 and part3
mov v0.d[1], v2.d[0] // part0123 = zip values from part01 and part23
addp v0.4S, v0.4S, v1.4S // part01 horizontal pair adding
addp v2.4S, v2.4S, v3.4S // part23 horizontal pair adding
addp v0.4S, v0.4S, v2.4S // part0123 horizontal pair adding
subs w2, w2, #4 // dstW -= 4
sqshrn v0.4H, v0.4S, #7 // shift and clip the 2x16-bit final values
st1 {v0.4H}, [x1], #8 // write to destination part0123