arm64: mc: Implement 8tap and bilin functions

These functions have been tuned against Cortex A53 and Snapdragon
835. The bilin functions have mainly been written with code size
in mind, as they aren't used much in practice.

Relative speedups for the actual filtering fuctions (that don't
just do a plain copy) are around 4-15x, some over 20x. This is
in comparison with GCC 5.4 with autovectorization disabled; the
actual real-world speedup against autovectorized C code is around
4-10x.

Relative speedups measured with checkasm:
                                Cortex A53   Snapdragon 835
mc_8tap_regular_w2_0_8bpc_neon:       6.96   5.28
mc_8tap_regular_w2_h_8bpc_neon:       5.16   4.35
mc_8tap_regular_w2_hv_8bpc_neon:      5.37   4.98
mc_8tap_regular_w2_v_8bpc_neon:       6.35   4.85
mc_8tap_regular_w4_0_8bpc_neon:       6.78   5.73
mc_8tap_regular_w4_h_8bpc_neon:       8.40   6.60
mc_8tap_regular_w4_hv_8bpc_neon:      7.23   7.10
mc_8tap_regular_w4_v_8bpc_neon:       9.06   7.76
mc_8tap_regular_w8_0_8bpc_neon:       6.96   5.55
mc_8tap_regular_w8_h_8bpc_neon:      10.36   6.88
mc_8tap_regular_w8_hv_8bpc_neon:      9.49   6.86
mc_8tap_regular_w8_v_8bpc_neon:      12.06   9.61
mc_8tap_regular_w16_0_8bpc_neon:      6.68   4.51
mc_8tap_regular_w16_h_8bpc_neon:     12.30   7.77
mc_8tap_regular_w16_hv_8bpc_neon:     9.50   6.68
mc_8tap_regular_w16_v_8bpc_neon:     12.93   9.68
mc_8tap_regular_w32_0_8bpc_neon:      3.91   2.93
mc_8tap_regular_w32_h_8bpc_neon:     13.06   7.89
mc_8tap_regular_w32_hv_8bpc_neon:     9.37   6.70
mc_8tap_regular_w32_v_8bpc_neon:     12.88   9.49
mc_8tap_regular_w64_0_8bpc_neon:      2.89   1.68
mc_8tap_regular_w64_h_8bpc_neon:     13.48   8.00
mc_8tap_regular_w64_hv_8bpc_neon:     9.23   6.53
mc_8tap_regular_w64_v_8bpc_neon:     13.11   9.68
mc_8tap_regular_w128_0_8bpc_neon:     1.89   1.24
mc_8tap_regular_w128_h_8bpc_neon:    13.58   7.98
mc_8tap_regular_w128_hv_8bpc_neon:    8.86   6.53
mc_8tap_regular_w128_v_8bpc_neon:    12.46   9.63
mc_bilinear_w2_0_8bpc_neon:           7.02   5.40
mc_bilinear_w2_h_8bpc_neon:           3.65   3.14
mc_bilinear_w2_hv_8bpc_neon:          4.36   4.84
mc_bilinear_w2_v_8bpc_neon:           5.22   4.28
mc_bilinear_w4_0_8bpc_neon:           6.87   5.99
mc_bilinear_w4_h_8bpc_neon:           6.50   8.61
mc_bilinear_w4_hv_8bpc_neon:          7.70   7.99
mc_bilinear_w4_v_8bpc_neon:           7.04   9.10
mc_bilinear_w8_0_8bpc_neon:           7.03   5.70
mc_bilinear_w8_h_8bpc_neon:          11.30  15.14
mc_bilinear_w8_hv_8bpc_neon:         15.74  13.50
mc_bilinear_w8_v_8bpc_neon:          13.40  17.54
mc_bilinear_w16_0_8bpc_neon:          6.75   4.48
mc_bilinear_w16_h_8bpc_neon:         17.02  13.95
mc_bilinear_w16_hv_8bpc_neon:        17.37  13.78
mc_bilinear_w16_v_8bpc_neon:         23.69  22.98
mc_bilinear_w32_0_8bpc_neon:          3.88   3.18
mc_bilinear_w32_h_8bpc_neon:         18.80  14.97
mc_bilinear_w32_hv_8bpc_neon:        17.74  14.02
mc_bilinear_w32_v_8bpc_neon:         24.46  23.04
mc_bilinear_w64_0_8bpc_neon:          2.87   1.66
mc_bilinear_w64_h_8bpc_neon:         19.54  16.02
mc_bilinear_w64_hv_8bpc_neon:        17.80  14.32
mc_bilinear_w64_v_8bpc_neon:         24.79  23.63
mc_bilinear_w128_0_8bpc_neon:         2.13   1.23
mc_bilinear_w128_h_8bpc_neon:        19.89  16.24
mc_bilinear_w128_hv_8bpc_neon:       17.55  14.15
mc_bilinear_w128_v_8bpc_neon:        24.45  23.54
mct_8tap_regular_w4_0_8bpc_neon:      5.56   5.51
mct_8tap_regular_w4_h_8bpc_neon:      7.48   5.80
mct_8tap_regular_w4_hv_8bpc_neon:     7.27   7.09
mct_8tap_regular_w4_v_8bpc_neon:      7.80   6.84
mct_8tap_regular_w8_0_8bpc_neon:      9.54   9.25
mct_8tap_regular_w8_h_8bpc_neon:      9.08   6.55
mct_8tap_regular_w8_hv_8bpc_neon:     9.16   6.30
mct_8tap_regular_w8_v_8bpc_neon:     10.79   8.66
mct_8tap_regular_w16_0_8bpc_neon:    15.35  10.50
mct_8tap_regular_w16_h_8bpc_neon:    10.18   6.76
mct_8tap_regular_w16_hv_8bpc_neon:    9.17   6.11
mct_8tap_regular_w16_v_8bpc_neon:    11.52   8.72
mct_8tap_regular_w32_0_8bpc_neon:    15.82  10.09
mct_8tap_regular_w32_h_8bpc_neon:    10.75   6.85
mct_8tap_regular_w32_hv_8bpc_neon:    9.00   6.22
mct_8tap_regular_w32_v_8bpc_neon:    11.58   8.67
mct_8tap_regular_w64_0_8bpc_neon:    15.28   9.68
mct_8tap_regular_w64_h_8bpc_neon:    10.93   6.96
mct_8tap_regular_w64_hv_8bpc_neon:    8.81   6.53
mct_8tap_regular_w64_v_8bpc_neon:    11.42   8.73
mct_8tap_regular_w128_0_8bpc_neon:   14.41   7.67
mct_8tap_regular_w128_h_8bpc_neon:   10.92   6.96
mct_8tap_regular_w128_hv_8bpc_neon:   8.56   6.51
mct_8tap_regular_w128_v_8bpc_neon:   11.16   8.70
mct_bilinear_w4_0_8bpc_neon:          5.66   5.77
mct_bilinear_w4_h_8bpc_neon:          5.16   6.40
mct_bilinear_w4_hv_8bpc_neon:         6.86   6.82
mct_bilinear_w4_v_8bpc_neon:          4.75   6.09
mct_bilinear_w8_0_8bpc_neon:          9.78  10.00
mct_bilinear_w8_h_8bpc_neon:          8.98  11.37
mct_bilinear_w8_hv_8bpc_neon:        14.42  10.83
mct_bilinear_w8_v_8bpc_neon:          9.12  11.62
mct_bilinear_w16_0_8bpc_neon:        15.59  10.76
mct_bilinear_w16_h_8bpc_neon:        11.98   8.77
mct_bilinear_w16_hv_8bpc_neon:       15.83  10.73
mct_bilinear_w16_v_8bpc_neon:        14.70  14.60
mct_bilinear_w32_0_8bpc_neon:        15.89  10.32
mct_bilinear_w32_h_8bpc_neon:        13.47   9.07
mct_bilinear_w32_hv_8bpc_neon:       16.01  10.95
mct_bilinear_w32_v_8bpc_neon:        14.85  14.16
mct_bilinear_w64_0_8bpc_neon:        15.36  10.51
mct_bilinear_w64_h_8bpc_neon:        14.00   9.61
mct_bilinear_w64_hv_8bpc_neon:       15.82  11.27
mct_bilinear_w64_v_8bpc_neon:        14.61  14.76
mct_bilinear_w128_0_8bpc_neon:       14.41   7.92
mct_bilinear_w128_h_8bpc_neon:       13.31   9.58
mct_bilinear_w128_hv_8bpc_neon:      14.07  11.18
mct_bilinear_w128_v_8bpc_neon:       11.57  14.42

1 files changed, 2 insertions, 0 deletions

diff --git a/src/arm/asm.S b/src/arm/asm.S
index 0b2291b..e5722cf 100644
--- a/src/arm/asm.S
+++ b/src/arm/asm.S
@@ -129,4 +129,6 @@ EXTERN\name:
 #define L(x) .L ## x
 #endif
 
+#define X(x) CONCAT(EXTERN, x)
+
 #endif /* __DAV1D_SRC_ARM_ASM_S__ */