On Mon, 26 Sep 2022, Grzegorz Bernacki wrote:
Provide optimized implementation of pix_abs8 function for arm64.
Performance comparison tests are shown below:
pix_abs_1_1_c: 162.5
pix_abs_1_1_neon: 27.0
pix_abs_1_2_c: 174.0
pix_abs_1_2_neon: 23.5
pix_abs_1_3_c: 203.2
pix_abs_1_3_neon: 34.7
Benchmarks and tests are run with checkasm tool on AWS Graviton 3.
Signed-off-by: Grzegorz Bernacki <g...@semihalf.com>
---
libavcodec/aarch64/me_cmp_init_aarch64.c | 9 ++
libavcodec/aarch64/me_cmp_neon.S | 193 +++++++++++++++++++++++
2 files changed, 202 insertions(+)
I don't see any changes compared to the version you sent last week? If
reposting a patchset, please do mention what has changed - or ping the old
one. (I had it on my radar to review, but reviews of larger amounts of
code doesn't happen immediately, unfortunately.)
Overall, you seem to have mixed in tabs among regular spaces. Please do
fix that. (I would have kinda expected us to have a fate test that checks
this, but apparently we don't.)
diff --git a/libavcodec/aarch64/me_cmp_init_aarch64.c
b/libavcodec/aarch64/me_cmp_init_aarch64.c
index e143f0816e..3459403ee5 100644
--- a/libavcodec/aarch64/me_cmp_init_aarch64.c
+++ b/libavcodec/aarch64/me_cmp_init_aarch64.c
@@ -59,6 +59,12 @@ int pix_median_abs16_neon(MpegEncContext *v, const uint8_t
*pix1, const uint8_t
ptrdiff_t stride, int h);
int pix_median_abs8_neon(MpegEncContext *v, const uint8_t *pix1, const uint8_t
*pix2,
ptrdiff_t stride, int h);
+int ff_pix_abs8_x2_neon(MpegEncContext *v, const uint8_t *pix1, const uint8_t
*pix2,
+ ptrdiff_t stride, int h);
+int ff_pix_abs8_y2_neon(MpegEncContext *v, const uint8_t *pix1, const uint8_t
*pix2,
+ ptrdiff_t stride, int h);
+int ff_pix_abs8_xy2_neon(MpegEncContext *v, const uint8_t *pix1, const uint8_t
*pix2,
+ ptrdiff_t stride, int h);
av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
{
@@ -70,6 +76,9 @@ av_cold void ff_me_cmp_init_aarch64(MECmpContext *c,
AVCodecContext *avctx)
c->pix_abs[0][2] = ff_pix_abs16_y2_neon;
c->pix_abs[0][3] = ff_pix_abs16_xy2_neon;
c->pix_abs[1][0] = ff_pix_abs8_neon;
+ c->pix_abs[1][1] = ff_pix_abs8_x2_neon;
+ c->pix_abs[1][2] = ff_pix_abs8_y2_neon;
+ c->pix_abs[1][3] = ff_pix_abs8_xy2_neon;
In most mediums, the diff here shows that there's something off - tabs.
c->sad[0] = ff_pix_abs16_neon;
c->sad[1] = ff_pix_abs8_neon;
diff --git a/libavcodec/aarch64/me_cmp_neon.S b/libavcodec/aarch64/me_cmp_neon.S
index 11af4849f9..e03c0c26cd 100644
--- a/libavcodec/aarch64/me_cmp_neon.S
+++ b/libavcodec/aarch64/me_cmp_neon.S
@@ -119,6 +119,199 @@ function ff_pix_abs8_neon, export=1
ret
endfunc
+function ff_pix_abs8_x2_neon, export=1
+ // x0 unused
+ // x1 uint8_t *pix1
+ // x2 uint8_t *pix2
+ // x3 ptrdiff_t stride
+ // w4 int h
+
+ cmp w4, #4
+ movi v26.8h, #0
+ add x5, x2, #1 // pix2 + 1
+ b.lt 2f
+
+// make 4 iterations at once
+1:
+ ld1 {v1.8b}, [x2], x3
+ ld1 {v2.8b}, [x5], x3
+ ld1 {v0.8b}, [x1], x3
+ ld1 {v4.8b}, [x2], x3
+ urhadd v30.8b, v1.8b, v2.8b
+ ld1 {v5.8b}, [x5], x3
+ uabal v26.8h, v0.8b, v30.8b
+ ld1 {v6.8b}, [x1], x3
+ urhadd v29.8b, v4.8b, v5.8b
+ ld1 {v7.8b}, [x2], x3
+ ld1 {v20.8b}, [x5], x3
+ uabal v26.8h, v6.8b, v29.8b
+ ld1 {v21.8b}, [x1], x3
+ urhadd v28.8b, v7.8b, v20.8b
+ ld1 {v22.8b}, [x2], x3
+ ld1 {v23.8b}, [x5], x3
+ uabal v26.8h, v21.8b, v28.8b
+ sub w4, w4, #4
+ ld1 {v24.8b}, [x1], x3
+ urhadd v27.8b, v22.8b, v23.8b
+ cmp w4, #4
+ uabal v26.8h, v24.8b, v27.8b
+
+ b.ge 1b
+ cbz w4, 3f
+
+// iterate by one
+2:
+ ld1 {v1.8b}, [x2], x3
+ ld1 {v2.8b}, [x5], x3
+ ld1 {v0.8b}, [x1], x3
+ urhadd v30.8b, v1.8b, v2.8b
+ subs w4, w4, #1
+ uabal v26.8h, v0.8b, v30.8b
+
+ b.ne 2b
+3:
+ uaddlv s20, v26.8h
+ fmov w0, s20
+
+ ret
+
+endfunc
+
+function ff_pix_abs8_y2_neon, export=1
+ // x0 unused
+ // x1 uint8_t *pix1
+ // x2 uint8_t *pix2
+ // x3 ptrdiff_t stride
+ // w4 int h
+
+ cmp w4, #4
+ movi v26.8h, #0
+ ld1 {v1.8b}, [x2], x3
+ b.lt 2f
+
+// make 4 iterations at once
+1:
+ ld1 {v2.8b}, [x2], x3
+ ld1 {v0.8b}, [x1], x3
+ ld1 {v6.8b}, [x1], x3
+ urhadd v30.8b, v1.8b, v2.8b
Good thing that you wrote this better than the current
ff_pix_abs16_y2_neon, reusing the data from the previous round. But the
scheduling could be much improved here (why load v6 directly after v0 - x1
will delay it due to being updated in the previous instruction, and v6
won't be needed for a long time here yet).
By fixing the scheduling of this function (and getting rid of the
unnecessary mov instruction at the end of the unrolled loop), I got it
down from 74 cycles to 62 cycles on a Cortex A53. I'm attaching the fixup
I did, so you can apply it on top instead of having to describe it
verbally.
+ ld1 {v5.8b}, [x2], x3
+ ld1 {v21.8b}, [x1], x3
+ uabal v26.8h, v0.8b, v30.8b
+ urhadd v29.8b, v2.8b, v5.8b
+ ld1 {v20.8b}, [x2], x3
+ ld1 {v24.8b}, [x1], x3
+ uabal v26.8h, v6.8b, v29.8b
+ urhadd v28.8b, v5.8b, v20.8b
+ uabal v26.8h, v21.8b, v28.8b
+ ld1 {v23.8b}, [x2], x3
+ mov v1.8b, v23.8b
+ sub w4, w4, #4
+ urhadd v27.8b, v20.8b, v23.8b
+ cmp w4, #4
+ uabal v26.8h, v24.8b, v27.8b
+
+ b.ge 1b
+ cbz w4, 3f
+
+// iterate by one
+2:
+ ld1 {v0.8b}, [x1], x3
+ ld1 {v2.8b}, [x2], x3
+ urhadd v30.8b, v1.8b, v2.8b
+ subs w4, w4, #1
+ uabal v26.8h, v0.8b, v30.8b
+ mov v1.8b, v2.8b
+
+ b.ne 2b
+3:
+ uaddlv s20, v26.8h
+ fmov w0, s20
+
+ ret
+
+endfunc
+
+function ff_pix_abs8_xy2_neon, export=1
+ // x0 unused
+ // x1 uint8_t *pix1
+ // x2 uint8_t *pix2
+ // x3 ptrdiff_t stride
+ // w4 int h
+
+ movi v31.8h, #0
+ add x0, x2, 1 // pix2 + 1
+
+ add x5, x2, x3 // pix2 + stride = pix3
+ cmp w4, #4
+ add x6, x5, 1 // pix3 + stride + 1
+
+ b.lt 2f
+
+ ld1 {v0.8b}, [x2], x3
+ ld1 {v1.8b}, [x0], x3
+ uaddl v2.8h, v0.8b, v1.8b
If we'd start out with h<4, we'd jump to the 2f label above, missing the
setup of v0-v2 here.
Other than that, the patch looks reasonable to me.
// Martin
From 7909432b3cffdcb31c0953279d862f820a738ec4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <mar...@martin.st>
Date: Wed, 28 Sep 2022 11:29:57 +0300
Subject: [PATCH 1/2] aarch64: me_cmp: Improve scheduling in
ff_pix_abs8_y2_neon
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Before: Cortex A53 A72 A73
pix_abs_1_2_neon: 73.7 31.0 25.7
After:
pix_abs_1_2_neon: 61.7 30.2 24.7
Signed-off-by: Martin Storsjö <mar...@martin.st>
---
libavcodec/aarch64/me_cmp_neon.S | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/libavcodec/aarch64/me_cmp_neon.S b/libavcodec/aarch64/me_cmp_neon.S
index a900ae2190..7f2b7c754f 100644
--- a/libavcodec/aarch64/me_cmp_neon.S
+++ b/libavcodec/aarch64/me_cmp_neon.S
@@ -193,21 +193,20 @@ function ff_pix_abs8_y2_neon, export=1
1:
ld1 {v2.8b}, [x2], x3
ld1 {v0.8b}, [x1], x3
- ld1 {v6.8b}, [x1], x3
urhadd v30.8b, v1.8b, v2.8b
ld1 {v5.8b}, [x2], x3
- ld1 {v21.8b}, [x1], x3
+ ld1 {v6.8b}, [x1], x3
uabal v26.8h, v0.8b, v30.8b
urhadd v29.8b, v2.8b, v5.8b
ld1 {v20.8b}, [x2], x3
- ld1 {v24.8b}, [x1], x3
+ ld1 {v21.8b}, [x1], x3
uabal v26.8h, v6.8b, v29.8b
urhadd v28.8b, v5.8b, v20.8b
- uabal v26.8h, v21.8b, v28.8b
- ld1 {v23.8b}, [x2], x3
- mov v1.8b, v23.8b
+ ld1 {v1.8b}, [x2], x3
+ ld1 {v24.8b}, [x1], x3
+ urhadd v27.8b, v20.8b, v1.8b
sub w4, w4, #4
- urhadd v27.8b, v20.8b, v23.8b
+ uabal v26.8h, v21.8b, v28.8b
cmp w4, #4
uabal v26.8h, v24.8b, v27.8b
--
2.25.1
From dfc91453aa3608b6b6b7c0e832292668150fd0d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <mar...@martin.st>
Date: Wed, 28 Sep 2022 11:43:02 +0300
Subject: [PATCH 2/2] aarch64: me_cmp: Fix up the prologue of
ff_pix_abs8_xy2_neon
This initializes things properly if this were to be called with
h < 4.
---
libavcodec/aarch64/me_cmp_neon.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/libavcodec/aarch64/me_cmp_neon.S b/libavcodec/aarch64/me_cmp_neon.S
index 7f2b7c754f..4037953488 100644
--- a/libavcodec/aarch64/me_cmp_neon.S
+++ b/libavcodec/aarch64/me_cmp_neon.S
@@ -245,12 +245,12 @@ function ff_pix_abs8_xy2_neon, export=1
cmp w4, #4
add x6, x5, 1 // pix3 + stride + 1
- b.lt 2f
-
ld1 {v0.8b}, [x2], x3
ld1 {v1.8b}, [x0], x3
uaddl v2.8h, v0.8b, v1.8b
+ b.lt 2f
+
// make 4 iterations at once
1:
ld1 {v4.8b}, [x5], x3
--
2.25.1
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