[FFmpeg-devel] [PATCH 2/5] lavc/aarch64: Add neon implementation of vsse16

[Hubert Mazur <hum@semihalf.com>]

Provide optimized implementation of vsse16 for arm64.

Performance comparison tests are shown below.
- vsse_0_c: 254.4
- vsse_0_neon: 64.7

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

Signed-off-by: Hubert Mazur <hum@semihalf.com>
---
 libavcodec/aarch64/me_cmp_init_aarch64.c |  4 +
 libavcodec/aarch64/me_cmp_neon.S         | 97 ++++++++++++++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/libavcodec/aarch64/me_cmp_init_aarch64.c b/libavcodec/aarch64/me_cmp_init_aarch64.c
index ddc5d05611..7b81e48d16 100644
--- a/libavcodec/aarch64/me_cmp_init_aarch64.c
+++ b/libavcodec/aarch64/me_cmp_init_aarch64.c
@@ -43,6 +43,8 @@ int sse4_neon(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
 
 int vsad16_neon(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2,
                 ptrdiff_t stride, int h);
+int vsse16_neon(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2,
+                ptrdiff_t stride, int h);
 
 av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
 {
@@ -62,5 +64,7 @@ av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
         c->sse[2] = sse4_neon;
 
         c->vsad[0] = vsad16_neon;
+
+        c->vsse[0] = vsse16_neon;
     }
 }
diff --git a/libavcodec/aarch64/me_cmp_neon.S b/libavcodec/aarch64/me_cmp_neon.S
index d4c0099854..279bae7cb5 100644
--- a/libavcodec/aarch64/me_cmp_neon.S
+++ b/libavcodec/aarch64/me_cmp_neon.S
@@ -659,3 +659,100 @@ function vsad16_neon, export=1
 
         ret
 endfunc
+
+function vsse16_neon, export=1
+        // x0           unused
+        // x1           uint8_t *pix1
+        // x2           uint8_t *pix2
+        // x3           ptrdiff_t stride
+        // w4           int h
+
+        movi            v30.4s, #0
+        movi            v29.4s, #0
+
+        add             x5, x1, x3                      // pix1 + stride
+        add             x6, x2, x3                      // pix2 + stride
+        sub             w4, w4, #1                      // we need to make h-1 iterations
+        cmp             w4, #3                          // check if we can make 4 iterations at once
+        b.le            2f
+
+// make 4 iterations at once
+1:
+        // x = abs(pix1[0] - pix2[0] - pix1[0 + stride] + pix2[0 + stride]) =
+        // res = (x) * (x)
+        ld1             {v0.16b}, [x1], x3              // Load pix1[0], first iteration
+        ld1             {v1.16b}, [x2], x3              // Load pix2[0], first iteration
+        ld1             {v2.16b}, [x5], x3              // Load pix1[0 + stride], first iteration
+        usubl           v28.8h, v0.8b, v1.8b            // Signed difference of pix1[0] - pix2[0], first iteration
+        ld1             {v3.16b}, [x6], x3              // Load pix2[0 + stride], first iteration
+        usubl2          v27.8h, v0.16b, v1.16b          // Signed difference of pix1[0] - pix2[0], first iteration
+        usubl           v26.8h, v3.8b, v2.8b            // Signed difference of pix1[0 + stride] - pix2[0 + stride], first iteration
+        usubl2          v25.8h, v3.16b, v2.16b          // Signed difference of pix1[0 + stride] - pix2[0 + stride], first iteration
+        ld1             {v4.16b}, [x1], x3              // Load pix1[0], second iteration
+        sqadd           v28.8h, v28.8h, v26.8h          // Add first iteration
+        ld1             {v6.16b}, [x5], x3              // Load pix1[0 + stride], second iteration
+        sqadd           v27.8h, v27.8h, v25.8h          // Add first iteration
+        ld1             {v5.16b}, [x2], x3              // Load pix2[0], second iteration
+        smlal           v30.4s, v28.4h, v28.4h          // Multiply-accumulate first iteration
+        ld1             {v7.16b}, [x6], x3              // Load pix2[0 + stride], second iteration
+        usubl           v26.8h, v4.8b, v5.8b            // Signed difference of pix1[0] - pix2[0], second iteration
+        smlal2          v29.4s, v28.8h, v28.8h          // Multiply-accumulate first iteration
+        usubl2          v25.8h, v4.16b, v5.16b          // Signed difference of pix1[0] - pix2[0], second iteration
+        usubl           v24.8h, v7.8b, v6.8b            // Signed difference of pix1[0 + stride] - pix2[0 + stride], first iteration
+        smlal           v30.4s, v27.4h, v27.4h          // Multiply-accumulate first iteration
+        usubl2          v23.8h, v7.16b, v6.16b          // Signed difference of pix1[0 + stride] - pix2[0 + stride], first iteration
+        sqadd           v24.8h, v26.8h, v24.8h          // Add second iteration
+        smlal2          v29.4s, v27.8h, v27.8h          // Multiply-accumulate first iteration
+        sqadd           v23.8h, v25.8h, v23.8h          // Add second iteration
+        ld1             {v18.16b}, [x1], x3             // Load pix1[0], third iteration
+        smlal           v30.4s, v24.4h, v24.4h          // Multiply-accumulate second iteration
+        ld1             {v31.16b}, [x2], x3             // Load pix2[0], third iteration
+        ld1             {v17.16b}, [x5], x3             // Load pix1[0 + stride], third iteration
+        smlal2          v29.4s, v24.8h, v24.8h          // Multiply-accumulate second iteration
+        ld1             {v16.16b}, [x6], x3             // Load pix2[0 + stride], third iteration
+        usubl           v22.8h, v18.8b, v31.8b          // Signed difference of pix1[0] - pix2[0], third iteration
+        smlal           v30.4s, v23.4h, v23.4h          // Multiply-accumulate second iteration
+        usubl2          v21.8h, v18.16b, v31.16b        // Signed difference of pix1[0] - pix2[0], third iteration
+        usubl           v20.8h, v16.8b, v17.8b          // Signed difference of pix1[0 + stride] - pix2[0 + stride], first iteration
+        smlal2          v29.4s, v23.8h, v23.8h          // Multiply-accumulate second iteration
+        sqadd           v20.8h, v22.8h, v20.8h          // Add third iteration
+        usubl2          v19.8h, v16.16b, v17.16b        // Signed difference of pix1[0 + stride] - pix2[0 + stride], first iteration
+        smlal           v30.4s, v20.4h, v20.4h          // Multiply-accumulate third iteration
+        sqadd           v19.8h, v21.8h, v19.8h          // Add third iteration
+        smlal2          v29.4s, v20.8h, v20.8h          // Multiply-accumulate third iteration
+        sub             w4, w4, #3
+        smlal           v30.4s, v19.4h, v19.4h          // Multiply-accumulate third iteration
+        cmp             w4, #3
+        smlal2          v29.4s, v19.8h, v19.8h          // Multiply-accumulate third iteration
+
+        b.ge            1b
+
+        cbz             w4, 3f
+
+// iterate by once
+2:
+        ld1             {v0.16b}, [x1], x3
+        ld1             {v1.16b}, [x2], x3
+        ld1             {v2.16b}, [x5], x3
+        usubl           v28.8h, v0.8b, v1.8b
+        ld1             {v3.16b}, [x6], x3
+        usubl2          v27.8h, v0.16b, v1.16b
+        usubl           v26.8h, v3.8b, v2.8b
+        usubl2          v25.8h, v3.16b, v2.16b
+        sqadd           v28.8h, v28.8h, v26.8h
+        sqadd           v27.8h, v27.8h, v25.8h
+        smlal           v30.4s, v28.4h, v28.4h
+        smlal2          v29.4s, v28.8h, v28.8h
+        subs            w4, w4, #1
+        smlal           v30.4s, v27.4h, v27.4h
+        smlal2          v29.4s, v27.8h, v27.8h
+
+        b.ne            2b
+
+3:
+        add             v30.4s, v30.4s, v29.4s
+        saddlv          d17, v30.4s
+        fmov            w0, s17
+
+        ret
+endfunc
-- 
2.34.1

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