[FFmpeg-devel] [PATCH 4/4] lavc/aarch64: Add neon implementation for vsse_intra8

[Grzegorz Bernacki <gjb@semihalf.com>]

Provide optimized implementation for vsse_intra8 for arm64.

Performance tests are shown below.
- vsse_5_c: 87.7
- vsse_5_neon: 26.2

Benchmarks and tests are run with checkasm tool on AWS Graviton 3.
---
 libavcodec/aarch64/me_cmp_init_aarch64.c |  4 ++
 libavcodec/aarch64/me_cmp_neon.S         | 53 ++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/libavcodec/aarch64/me_cmp_init_aarch64.c b/libavcodec/aarch64/me_cmp_init_aarch64.c
index f247372c94..defec37478 100644
--- a/libavcodec/aarch64/me_cmp_init_aarch64.c
+++ b/libavcodec/aarch64/me_cmp_init_aarch64.c
@@ -74,6 +74,9 @@ int nsse8_neon_wrapper(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2,
 int vsse8_neon(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2,
                ptrdiff_t stride, int h);
 
+int vsse_intra8_neon(MpegEncContext *c, const uint8_t *s, const uint8_t *dummy,
+                     ptrdiff_t stride, int h);
+
 av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
 {
     int cpu_flags = av_get_cpu_flags();
@@ -102,6 +105,7 @@ av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
         c->vsse[1] = vsse8_neon;
 
         c->vsse[4] = vsse_intra16_neon;
+        c->vsse[5] = vsse_intra8_neon;
 
         c->nsse[0] = nsse16_neon_wrapper;
         c->nsse[1] = nsse8_neon_wrapper;
diff --git a/libavcodec/aarch64/me_cmp_neon.S b/libavcodec/aarch64/me_cmp_neon.S
index 386d2de0c5..82ff05d3f0 100644
--- a/libavcodec/aarch64/me_cmp_neon.S
+++ b/libavcodec/aarch64/me_cmp_neon.S
@@ -1111,6 +1111,59 @@ function vsse_intra16_neon, export=1
         ret
 endfunc
 
+function vsse_intra8_neon, export=1
+        // x0           unused
+        // x1           uint8_t *pix1
+        // x2           uint8_t *dummy
+        // x3           ptrdiff_t stride
+        // w4           int h
+
+        ld1             {v0.8b}, [x1], x3
+        movi            v16.4s, #0
+
+        sub             w4, w4, #1 // we need to make h-1 iterations
+        cmp             w4, #3
+        b.lt            2f
+
+1:
+        // v = abs( pix1[0] - pix1[0 + stride] )
+        // score = sum( v * v )
+        ld1             {v1.8b}, [x1], x3
+        ld1             {v2.8b}, [x1], x3
+        uabd            v30.8b, v0.8b, v1.8b
+        ld1             {v3.8b}, [x1], x3
+        umull           v29.8h, v30.8b, v30.8b
+        uabd            v27.8b, v1.8b, v2.8b
+        uadalp          v16.4s, v29.8h
+        umull           v26.8h, v27.8b, v27.8b
+        uabd            v25.8b, v2.8b, v3.8b
+        uadalp          v16.4s, v26.8h
+        umull           v24.8h, v25.8b, v25.8b
+        sub             w4, w4, #3
+        uadalp          v16.4s, v24.8h
+        cmp             w4, #3
+        mov             v0.8b, v3.8b
+
+        b.ge            1b
+        cbz             w4, 3f
+
+// iterate by one
+2:
+        ld1             {v1.8b}, [x1], x3
+        subs            w4, w4, #1
+        uabd            v30.8b, v0.8b, v1.8b
+        mov             v0.8b, v1.8b
+        umull           v29.8h, v30.8b, v30.8b
+        uadalp          v16.4s, v29.8h
+        cbnz            w4, 2b
+
+3:
+        uaddlv          d17, v16.4s
+        fmov            w0, s17
+
+        ret
+endfunc
+
 function nsse16_neon, export=1
         // x0           multiplier
         // x1           uint8_t *pix1
-- 
2.25.1

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