[FFmpeg-devel] [PATCH 5/5] lavc/aarch64: Provide neon implementation of nsse16

[Hubert Mazur <hum@semihalf.com>]

Add vectorized implementation of nsse16 function.

Performance comparison tests are shown below.
- nsse_0_c: 707.0
- nsse_0_neon: 120.0

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

Signed-off-by: Hubert Mazur <hum@semihalf.com>
---
 libavcodec/aarch64/me_cmp_init_aarch64.c |  15 +++
 libavcodec/aarch64/me_cmp_neon.S         | 126 +++++++++++++++++++++++
 2 files changed, 141 insertions(+)

diff --git a/libavcodec/aarch64/me_cmp_init_aarch64.c b/libavcodec/aarch64/me_cmp_init_aarch64.c
index 8c295d5457..146ef04345 100644
--- a/libavcodec/aarch64/me_cmp_init_aarch64.c
+++ b/libavcodec/aarch64/me_cmp_init_aarch64.c
@@ -49,6 +49,10 @@ 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);
+int nsse16_neon(int multiplier, const uint8_t *s, const uint8_t *s2,
+                ptrdiff_t stride, int h);
+int nsse16_neon_wrapper(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)
 {
@@ -72,5 +76,16 @@ av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
 
         c->vsse[0] = vsse16_neon;
         c->vsse[4] = vsse_intra16_neon;
+
+        c->nsse[0] = nsse16_neon_wrapper;
     }
 }
+
+int nsse16_neon_wrapper(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2,
+                        ptrdiff_t stride, int h)
+{
+        if (c)
+            return nsse16_neon(c->avctx->nsse_weight, s1, s2, stride, h);
+        else
+            return nsse16_neon(8, s1, s2, stride, h);
+}
\ No newline at end of file
diff --git a/libavcodec/aarch64/me_cmp_neon.S b/libavcodec/aarch64/me_cmp_neon.S
index 46d4dade5d..9fe96e111c 100644
--- a/libavcodec/aarch64/me_cmp_neon.S
+++ b/libavcodec/aarch64/me_cmp_neon.S
@@ -889,3 +889,129 @@ function vsse_intra16_neon, export=1
 
         ret
 endfunc
+
+function nsse16_neon, export=1
+        // x0           multiplier
+        // x1           uint8_t *pix1
+        // x2           uint8_t *pix2
+        // x3           ptrdiff_t stride
+        // w4           int h
+
+        str             x0, [sp, #-0x40]!
+        stp             x1, x2, [sp, #0x10]
+        stp             x3, x4, [sp, #0x20]
+        str             lr, [sp, #0x30]
+        bl              sse16_neon
+        ldr             lr, [sp, #0x30]
+        mov             w9, w0                                  // here we store score1
+        ldr             x5, [sp]
+        ldp             x1, x2, [sp, #0x10]
+        ldp             x3, x4, [sp, #0x20]
+        add             sp, sp, #0x40
+
+        movi            v16.8h, #0
+        movi            v17.8h, #0
+        movi            v18.8h, #0
+        movi            v19.8h, #0
+
+        mov             x10, x1                                 // x1
+        mov             x14, x2                                 // x2
+        add             x11, x1, x3                             // x1 + stride
+        add             x15, x2, x3                             // x2 + stride
+        add             x12, x1, #1                             // x1 + 1
+        add             x16, x2, #1                             // x2 + 1
+        add             x13, x11, #1                            // x1 + stride + 1
+        add             x17, x15, #1                            // x2 + stride + 1
+
+        subs            w4, w4, #1                              // we need to make h-1 iterations
+        cmp             w4, #2
+        b.lt            2f
+
+// make 2 iterations at once
+1:
+        ld1             {v0.16b}, [x10], x3
+        ld1             {v1.16b}, [x11], x3
+        ld1             {v2.16b}, [x12], x3
+        usubl           v31.8h, v0.8b, v1.8b
+        ld1             {v3.16b}, [x13], x3
+        usubl2          v30.8h, v0.16b, v1.16b
+        usubl           v29.8h, v2.8b, v3.8b
+        usubl2          v28.8h, v2.16b, v3.16b
+        ld1             {v4.16b}, [x14], x3
+        saba            v16.8h, v31.8h, v29.8h
+        ld1             {v5.16b}, [x15], x3
+        ld1             {v6.16b}, [x16], x3
+        saba            v17.8h, v30.8h, v28.8h
+        ld1             {v7.16b}, [x17], x3
+        usubl           v27.8h, v4.8b, v5.8b
+        usubl2          v26.8h, v4.16b, v5.16b
+        usubl           v25.8h, v6.8b, v7.8b
+        ld1             {v31.16b}, [x10], x3
+        saba            v18.8h, v27.8h, v25.8h
+        usubl2          v24.8h, v6.16b, v7.16b
+        ld1             {v30.16b}, [x11], x3
+        ld1             {v29.16b}, [x12], x3
+        saba            v19.8h, v26.8h, v24.8h
+        usubl           v23.8h, v31.8b, v30.8b
+        ld1             {v28.16b}, [x13], x3
+        usubl2          v22.8h, v31.16b, v30.16b
+        usubl           v21.8h, v29.8b, v28.8b
+        ld1             {v27.16b}, [x14], x3
+        usubl2          v20.8h, v29.16b, v28.16b
+        saba            v16.8h, v23.8h, v21.8h
+        ld1             {v26.16b}, [x15], x3
+        ld1             {v25.16b}, [x16], x3
+        saba            v17.8h, v22.8h, v20.8h
+        ld1             {v24.16b}, [x17], x3
+        usubl           v31.8h, v27.8b, v26.8b
+        usubl           v29.8h, v25.8b, v24.8b
+        usubl2          v30.8h, v27.16b, v26.16b
+        saba            v18.8h, v31.8h, v29.8h
+        usubl2          v28.8h, v25.16b, v24.16b
+        sub             w4, w4, #2
+        cmp             w4, #2
+        saba            v19.8h, v30.8h, v28.8h
+
+        b.ge            1b
+        cbz             w4, 3f
+
+// iterate by one
+2:
+        ld1             {v0.16b}, [x10], x3
+        ld1             {v1.16b}, [x11], x3
+        ld1             {v2.16b}, [x12], x3
+        usubl           v31.8h, v0.8b, v1.8b
+        ld1             {v3.16b}, [x13], x3
+        usubl2          v30.8h, v0.16b, v1.16b
+        usubl           v29.8h, v2.8b, v3.8b
+        usubl2          v28.8h, v2.16b, v3.16b
+        saba            v16.8h, v31.8h, v29.8h
+        ld1             {v4.16b}, [x14], x3
+        ld1             {v5.16b}, [x15], x3
+        saba            v17.8h, v30.8h, v28.8h
+        ld1             {v6.16b}, [x16], x3
+        usubl           v27.8h, v4.8b, v5.8b
+        ld1             {v7.16b}, [x17], x3
+        usubl2          v26.8h, v4.16b, v5.16b
+        usubl           v25.8h, v6.8b, v7.8b
+        usubl2          v24.8h, v6.16b, v7.16b
+        saba            v18.8h, v27.8h, v25.8h
+        subs            w4, w4, #1
+        saba            v19.8h, v26.8h, v24.8h
+
+        cbnz            w4, 2b
+
+3:
+        sqsub           v16.8h, v16.8h, v18.8h
+        sqsub           v17.8h, v17.8h, v19.8h
+        ins             v17.h[7], wzr
+        sqadd           v16.8h, v16.8h, v17.8h
+        saddlv          s16, v16.8h
+        sqabs           s16, s16
+        fmov            w0, s16
+
+        mul             w0, w0, w5
+        add             w0, w0, w9
+
+        ret
+endfunc
-- 
2.34.1

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