This patch integrates so called double bufferring when we are loading
2 batch of elements at a time and then processing them in parallel. On the
moden arm processors especially Apple Silicon it gives a visible
benefit, for subsampled pixel processing it is especially nice because
it allows to read elements w/ 2 instructions and write with a single one
(especially visible on a platforms with slower memory like ios).
Including the previous patch in a stack on macbook pro m4 max rgb_to_yuv_half
in checkasm goes up 2x of the c version
---
libswscale/aarch64/input.S | 130 ++++++++++++++++++++++++++-----------
1 file changed, 91 insertions(+), 39 deletions(-)
diff --git a/libswscale/aarch64/input.S b/libswscale/aarch64/input.S
index 260a26e965..b90ca05996 100644
--- a/libswscale/aarch64/input.S
+++ b/libswscale/aarch64/input.S
@@ -178,7 +178,7 @@ rgbToY_neon abgr32, argb32, element=4, alpha_first=1
.macro rgbToUV_half_neon fmt_bgr, fmt_rgb, element, alpha_first=0
function ff_\fmt_bgr\()ToUV_half_neon, export=1
- cbz w5, 3f // check width > 0
+ cbz w5, 3f
ldp w12, w11, [x6, #12]
ldp w10, w15, [x6, #20]
@@ -187,49 +187,101 @@ function ff_\fmt_bgr\()ToUV_half_neon, export=1
endfunc
function ff_\fmt_rgb\()ToUV_half_neon, export=1
- cmp w5, #0 // check width > 0
+ cmp w5, #0
b.le 3f
- ldp w10, w11, [x6, #12] // w10: ru, w11: gu
- ldp w12, w13, [x6, #20] // w12: bu, w13: rv
- ldp w14, w15, [x6, #28] // w14: gv, w15: bv
+ ldp w10, w11, [x6, #12]
+ ldp w12, w13, [x6, #20]
+ ldp w14, w15, [x6, #28]
4:
- cmp w5, #8
rgb_set_uv_coeff half=1
+
+ cmp w5, #16
b.lt 2f
-1: // load 16 pixels
+
+1:
.if \element == 3
ld3 { v16.16b, v17.16b, v18.16b }, [x3], #48
+ ld3 { v26.16b, v27.16b, v28.16b }, [x3], #48
.else
ld4 { v16.16b, v17.16b, v18.16b, v19.16b }, [x3], #64
+ ld4 { v26.16b, v27.16b, v28.16b, v29.16b }, [x3], #64
.endif
.if \alpha_first
- uaddlp v21.8h, v19.16b // v21: summed b pairs
- uaddlp v20.8h, v18.16b // v20: summed g pairs
- uaddlp v19.8h, v17.16b // v19: summed r pairs
+ uaddlp v21.8h, v19.16b
+ uaddlp v20.8h, v18.16b
+ uaddlp v19.8h, v17.16b
+ uaddlp v31.8h, v29.16b
+ uaddlp v30.8h, v28.16b
+ uaddlp v29.8h, v27.16b
.else
- uaddlp v19.8h, v16.16b // v19: summed r pairs
- uaddlp v20.8h, v17.16b // v20: summed g pairs
- uaddlp v21.8h, v18.16b // v21: summed b pairs
+ uaddlp v19.8h, v16.16b
+ uaddlp v20.8h, v17.16b
+ uaddlp v21.8h, v18.16b
+ uaddlp v29.8h, v26.16b
+ uaddlp v30.8h, v27.16b
+ uaddlp v31.8h, v28.16b
.endif
- mov v22.16b, v6.16b // U first half
- mov v23.16b, v6.16b // U second half
- mov v24.16b, v6.16b // V first half
- mov v25.16b, v6.16b // V second half
-
- rgb_to_uv_interleaved_product v19, v20, v21, v0, v1, v2, v3, v4, v5,
v22, v23, v24, v25, v16, v17, #10
-
- str q16, [x0], #16 // store dst_u
- str q17, [x1], #16 // store dst_v
+ mov v7.16b, v6.16b
+ mov v16.16b, v6.16b
+ mov v17.16b, v6.16b
+ mov v18.16b, v6.16b
+ mov v26.16b, v6.16b
+ mov v27.16b, v6.16b
+ mov v28.16b, v6.16b
+ mov v25.16b, v6.16b
- sub w5, w5, #8 // width -= 8
- cmp w5, #8 // width >= 8 ?
+ smlal v7.4s, v0.4h, v19.4h
+ smlal v17.4s, v3.4h, v19.4h
+ smlal v26.4s, v0.4h, v29.4h
+ smlal v28.4s, v3.4h, v29.4h
+
+ smlal2 v16.4s, v0.8h, v19.8h
+ smlal2 v18.4s, v3.8h, v19.8h
+ smlal2 v27.4s, v0.8h, v29.8h
+ smlal2 v25.4s, v3.8h, v29.8h
+
+ smlal v7.4s, v1.4h, v20.4h
+ smlal v17.4s, v4.4h, v20.4h
+ smlal v26.4s, v1.4h, v30.4h
+ smlal v28.4s, v4.4h, v30.4h
+
+ smlal2 v16.4s, v1.8h, v20.8h
+ smlal2 v18.4s, v4.8h, v20.8h
+ smlal2 v27.4s, v1.8h, v30.8h
+ smlal2 v25.4s, v4.8h, v30.8h
+
+ smlal v7.4s, v2.4h, v21.4h
+ smlal v17.4s, v5.4h, v21.4h
+ smlal v26.4s, v2.4h, v31.4h
+ smlal v28.4s, v5.4h, v31.4h
+
+ smlal2 v16.4s, v2.8h, v21.8h
+ smlal2 v18.4s, v5.8h, v21.8h
+ smlal2 v27.4s, v2.8h, v31.8h
+ smlal2 v25.4s, v5.8h, v31.8h
+
+ sqshrn v19.4h, v7.4s, #10
+ sqshrn v20.4h, v17.4s, #10
+ sqshrn v22.4h, v26.4s, #10
+ sqshrn v23.4h, v28.4s, #10
+
+ sqshrn2 v19.8h, v16.4s, #10
+ sqshrn2 v20.8h, v18.4s, #10
+ sqshrn2 v22.8h, v27.4s, #10
+ sqshrn2 v23.8h, v25.4s, #10
+
+ stp q19, q22, [x0], #32
+ stp q20, q23, [x1], #32
+
+ sub w5, w5, #16
+ cmp w5, #16
b.ge 1b
- cbz w5, 3f // No pixels left? Exit
+ cbz w5, 3f
-2: // Scalar fallback for remaining pixels
+2:
.if \alpha_first
rgb_load_add_half 1, 5, 2, 6, 3, 7
.else
@@ -239,24 +291,24 @@ function ff_\fmt_rgb\()ToUV_half_neon, export=1
rgb_load_add_half 0, 4, 1, 5, 2, 6
.endif
.endif
- smaddl x8, w2, w10, x9 // dst_u = ru * r +
const_offset
- smaddl x16, w2, w13, x9 // dst_v = rv * r +
const_offset (parallel)
+ smaddl x8, w2, w10, x9
+ smaddl x16, w2, w13, x9
- smaddl x8, w4, w11, x8 // dst_u += gu * g
- smaddl x16, w4, w14, x16 // dst_v += gv * g (parallel)
+ smaddl x8, w4, w11, x8
+ smaddl x16, w4, w14, x16
- smaddl x8, w7, w12, x8 // dst_u += bu * b
- smaddl x16, w7, w15, x16 // dst_v += bv * b (parallel)
+ smaddl x8, w7, w12, x8
+ smaddl x16, w7, w15, x16
- asr w8, w8, #10 // dst_u >>= 10
- asr w16, w16, #10 // dst_v >>= 10
+ asr w8, w8, #10
+ asr w16, w16, #10
- strh w8, [x0], #2 // store dst_u
- strh w16, [x1], #2 // store dst_v
+ strh w8, [x0], #2
+ strh w16, [x1], #2
- sub w5, w5, #1 // width--
- add x3, x3, #(2*\element) // Advance source pointer
- cbnz w5, 2b // Process next pixel if any
left
+ sub w5, w5, #1
+ add x3, x3, #(2*\element)
+ cbnz w5, 2b
3:
ret
endfunc
--
2.49.0
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