[FFmpeg-devel] [PATCH 4/5] lavc/aarch64: Add neon implementation for vsse_intra16

[Hubert Mazur]

Provide optimized implementation for vsse_intra16 for arm64.

Performance tests are shown below.
- vsse_4_c: 153.7
- vsse_4_neon: 34.2

Benchmarks and tests are run with checkasm tool on AWS Graviton 3.

Signed-off-by: Hubert Mazur <hum at semihalf.com>
---
 libavcodec/aarch64/me_cmp_init_aarch64.c |  3 +
 libavcodec/aarch64/me_cmp_neon.S         | 75 ++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/libavcodec/aarch64/me_cmp_init_aarch64.c b/libavcodec/aarch64/me_cmp_init_aarch64.c
index af83f7ed1e..8c295d5457 100644
--- a/libavcodec/aarch64/me_cmp_init_aarch64.c
+++ b/libavcodec/aarch64/me_cmp_init_aarch64.c
@@ -47,6 +47,8 @@ int vsad_intra16_neon(MpegEncContext *c, const uint8_t *s, const uint8_t *dummy,
                       ptrdiff_t stride, int h) ;
 int vsse16_neon(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2,
                 ptrdiff_t stride, int h);
+int vsse_intra16_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)
 {
@@ -69,5 +71,6 @@ av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
         c->vsad[4] = vsad_intra16_neon;
 
         c->vsse[0] = vsse16_neon;
+        c->vsse[4] = vsse_intra16_neon;
     }
 }
diff --git a/libavcodec/aarch64/me_cmp_neon.S b/libavcodec/aarch64/me_cmp_neon.S
index 126e267fdc..46d4dade5d 100644
--- a/libavcodec/aarch64/me_cmp_neon.S
+++ b/libavcodec/aarch64/me_cmp_neon.S
@@ -814,3 +814,78 @@ function vsad_intra16_neon, export=1
 
         ret
 endfunc
+
+function vsse_intra16_neon, export=1
+        // x0           unused
+        // x1           uint8_t *pix1
+        // x2           uint8_t *dummy
+        // x3           ptrdiff_t stride
+        // w4           int h
+
+        add             x5, x1, x3 // pix1 + stride
+        movi            v16.4s, #0
+        movi            v17.4s, #0
+
+        sub             w4, w4, #1 // we need to make h-1 iterations
+        cmp             w4, #4
+        b.lt            2f
+
+// make 4 iterations at once
+1:
+        // v = abs( pix1[0] - pix1[0 + stride] )
+        // score = sum( v * v )
+        // abs(x) = ( (x > 0) ? (x) : (-x) )
+
+        ld1             {v0.16b}, [x1], x3
+        ld1             {v1.16b}, [x5], x3
+        ld1             {v2.16b}, [x1], x3
+        uabd            v30.16b, v0.16b, v1.16b
+        ld1             {v3.16b}, [x5], x3
+        ld1             {v4.16b}, [x1], x3
+        umull           v29.8h, v30.8b, v30.8b
+        umull2          v28.8h, v30.16b, v30.16b
+        uabd            v27.16b, v2.16b, v3.16b
+        uadalp          v16.4s, v29.8h
+        ld1             {v5.16b}, [x5], x3
+        umull           v26.8h, v27.8b, v27.8b
+        uadalp          v17.4s, v28.8h
+        ld1             {v6.16b}, [x1], x3
+        umull2          v27.8h, v27.16b, v27.16b
+        uabd            v25.16b, v4.16b, v5.16b
+        uadalp          v16.4s, v26.8h
+        umull           v24.8h, v25.8b, v25.8b
+        ld1             {v7.16b}, [x5], x3
+        uadalp          v17.4s, v27.8h
+        umull2          v25.8h, v25.16b, v25.16b
+        uabd            v23.16b, v6.16b, v7.16b
+        uadalp          v16.4s, v24.8h
+        umull           v22.8h, v23.8b, v23.8b
+        uadalp          v17.4s, v25.8h
+        umull2          v23.8h, v23.16b, v23.16b
+        sub             w4, w4, #4
+        uadalp          v16.4s, v22.8h
+        cmp             w4, #4
+        uadalp          v17.4s, v23.8h
+
+        b.ge            1b
+        cbz             w4, 3f
+
+// iterate by one
+2:
+        ld1             {v0.16b}, [x1], x3
+        ld1             {v1.16b}, [x5], x3
+        subs            w4, w4, #1
+        uabd            v30.16b, v0.16b, v1.16b
+        umull           v29.8h, v30.8b, v30.8b
+        umull2          v30.8h, v30.16b, v30.16b
+        uadalp          v16.4s, v29.8h
+        uadalp          v17.4s, v30.8h
+        cbnz            w4, 2b
+
+3:
+        add             v16.4s, v16.4s, v17.4S
+        uaddlv          d17, v16.4s
+        fmov            w0, s17
+
+        ret
+endfunc
-- 
2.34.1