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h264/aarch64: optimize neon loop filter
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Exit as soon as possible if no filtering will be done.

Improves the checkasm --bench cycle count on a Snapdragon 820e:
h264_h_loop_filter_luma_8bpp_c:      72.4 ->  72.5
h264_h_loop_filter_luma_8bpp_neon:   97.1 ->  56.3
h264_v_loop_filter_luma_8bpp_c:     174.0 -> 173.5
h264_v_loop_filter_luma_8bpp_neon:   62.9 ->  60.9
h264_h_loop_filter_chroma_8bpp_c:    30.2 ->  30.3
h264_h_loop_filter_chroma_8bpp_neon: 51.6 ->  25.7
h264_v_loop_filter_chroma_8bpp_c:    57.3 ->  57.3
h264_v_loop_filter_chroma_8bpp_neon: 28.0 ->  24.0
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Janne Grunau committed Jan 26, 2019
1 parent d7f4f5c commit 846c3d6
Showing 1 changed file with 19 additions and 14 deletions.
33 changes: 19 additions & 14 deletions libavcodec/aarch64/h264dsp_neon.S
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Original file line number Diff line number Diff line change
Expand Up @@ -54,9 +54,12 @@
uabd v17.16B, v20.16B, v16.16B // abs(p2 - p0)
and v21.16B, v21.16B, v28.16B
uabd v19.16B, v4.16B, v0.16B // abs(q2 - q0)
and v21.16B, v21.16B, v30.16B // < beta
shrn v30.8b, v21.8h, #4
mov x7, v30.d[0]
cmhi v17.16B, v22.16B, v17.16B // < beta
and v21.16B, v21.16B, v30.16B
cmhi v19.16B, v22.16B, v19.16B // < beta
cbz x7, 9f
and v17.16B, v17.16B, v21.16B
and v19.16B, v19.16B, v21.16B
and v24.16B, v24.16B, v21.16B
Expand Down Expand Up @@ -124,7 +127,7 @@ function ff_h264_v_loop_filter_luma_neon, export=1
st1 {v16.16B}, [x0], x1
st1 {v0.16B}, [x0], x1
st1 {v19.16B}, [x0]

9:
ret
endfunc

Expand Down Expand Up @@ -174,32 +177,34 @@ function ff_h264_h_loop_filter_luma_neon, export=1
st1 {v16.S}[3], [x0], x1
st1 {v0.S}[3], [x0], x1
st1 {v19.S}[3], [x0], x1

9:
ret
endfunc

.macro h264_loop_filter_chroma
dup v22.8B, w2 // alpha
dup v23.8B, w3 // beta
uxtl v24.8H, v24.8B
uabd v26.8B, v16.8B, v0.8B // abs(p0 - q0)
uxtl v4.8H, v0.8B
uabd v28.8B, v18.8B, v16.8B // abs(p1 - p0)
uabd v30.8B, v2.8B, v0.8B // abs(q1 - q0)
cmhi v26.8B, v22.8B, v26.8B // < alpha
cmhi v28.8B, v23.8B, v28.8B // < beta
cmhi v30.8B, v23.8B, v30.8B // < beta
uxtl v4.8H, v0.8B
and v26.8B, v26.8B, v28.8B
usubw v4.8H, v4.8H, v16.8B
sli v24.8H, v24.8H, #8
and v26.8B, v26.8B, v30.8B
shl v4.8H, v4.8H, #2
uabd v30.8B, v2.8B, v0.8B // abs(q1 - q0)
mov x2, v26.d[0]
sli v24.8H, v24.8H, #8
uaddw v4.8H, v4.8H, v18.8B
cmhi v26.8B, v22.8B, v26.8B // < alpha
cbz x2, 9f
usubw v4.8H, v4.8H, v2.8B
dup v22.8B, w3 // beta
rshrn v4.8B, v4.8H, #3
cmhi v28.8B, v22.8B, v28.8B // < beta
cmhi v30.8B, v22.8B, v30.8B // < beta
smin v4.8B, v4.8B, v24.8B
neg v25.8B, v24.8B
and v26.8B, v26.8B, v28.8B
smax v4.8B, v4.8B, v25.8B
and v26.8B, v26.8B, v30.8B
uxtl v22.8H, v0.8B
and v4.8B, v4.8B, v26.8B
uxtl v28.8H, v16.8B
Expand All @@ -224,7 +229,7 @@ function ff_h264_v_loop_filter_chroma_neon, export=1
sub x0, x0, x1, lsl #1
st1 {v16.8B}, [x0], x1
st1 {v0.8B}, [x0], x1

9:
ret
endfunc

Expand Down Expand Up @@ -257,7 +262,7 @@ function ff_h264_h_loop_filter_chroma_neon, export=1
st1 {v16.S}[1], [x0], x1
st1 {v0.S}[1], [x0], x1
st1 {v2.S}[1], [x0], x1

9:
ret
endfunc

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