before:

time ./avconv -v 0 -nostats -threads 1 -i sintel_vp9_500kbps.webm -f null -
real    0m11.125s
user    0m11.059s
sys     0m0.050s

time ./avconv -v 0 -nostats -threads 1 -i sintel_vp9_500kbps.webm -f null -
real    0m10.944s
user    0m10.819s
sys     0m0.064s

after:

time ./avconv -v 0 -nostats -threads 1 -i sintel_vp9_500kbps.webm -f null -
real    0m8.153s
user    0m8.034s
sys     0m0.050s

time ./avconv -v 0 -nostats -threads 1 -i sintel_vp9_500kbps.webm -f null -
real    0m8.038s
user    0m7.980s
sys     0m0.039s

Signed-off-by: Martin Storsjö <martin@martin.st>

This work is sponsored by, and copyright, Google.

These are ported from the ARM version; it is essentially a 1:1
port with no extra added features, but with some hand tuning
(especially for the plain copy/avg functions). The ARM version
isn't very register starved to begin with, so there's not much
to be gained from having more spare registers here - we only
avoid having to clobber callee-saved registers.

Examples of runtimes vs the 32 bit version, on a Cortex A53:
                                     ARM   AArch64
vp9_avg4_neon:                      27.2      23.7
vp9_avg8_neon:                      56.5      54.7
vp9_avg16_neon:                    169.9     167.4
vp9_avg32_neon:                    585.8     585.2
vp9_avg64_neon:                   2460.3    2294.7
vp9_avg_8tap_smooth_4h_neon:       132.7     125.2
vp9_avg_8tap_smooth_4hv_neon:      478.8     442.0
vp9_avg_8tap_smooth_4v_neon:       126.0      93.7
vp9_avg_8tap_smooth_8h_neon:       241.7     234.2
vp9_avg_8tap_smooth_8hv_neon:      690.9     646.5
vp9_avg_8tap_smooth_8v_neon:       245.0     205.5
vp9_avg_8tap_smooth_64h_neon:    11273.2   11280.1
vp9_avg_8tap_smooth_64hv_neon:   22980.6   22184.1
vp9_avg_8tap_smooth_64v_neon:    11549.7   10781.1
vp9_put4_neon:                      18.0      17.2
vp9_put8_neon:                      40.2      37.7
vp9_put16_neon:                     97.4      99.5
vp9_put32_neon/armv8:              346.0     307.4
vp9_put64_neon/armv8:             1319.0    1107.5
vp9_put_8tap_smooth_4h_neon:       126.7     118.2
vp9_put_8tap_smooth_4hv_neon:      465.7     434.0
vp9_put_8tap_smooth_4v_neon:       113.0      86.5
vp9_put_8tap_smooth_8h_neon:       229.7     221.6
vp9_put_8tap_smooth_8hv_neon:      658.9     621.3
vp9_put_8tap_smooth_8v_neon:       215.0     187.5
vp9_put_8tap_smooth_64h_neon:    10636.7   10627.8
vp9_put_8tap_smooth_64hv_neon:   21076.8   21026.9
vp9_put_8tap_smooth_64v_neon:     9635.0    9632.4

These are generally about as fast as the corresponding ARM
routines on the same CPU (at least on the A53), in most cases
marginally faster.

The speedup vs C code is pretty much the same as for the 32 bit
case; on the A53 it's around 6-13x for ther larger 8tap filters.
The exact speedup varies a little, since the C versions generally
don't end up exactly as slow/fast as on 32 bit.

Signed-off-by: Martin Storsjö <martin@martin.st>

Make them aligned, to allow efficient access to them from simd.

Signed-off-by: Martin Storsjö <martin@martin.st>

This work is sponsored by, and copyright, Google.

The filter coefficients are signed values, where the product of the
multiplication with one individual filter coefficient doesn't
overflow a 16 bit signed value (the largest filter coefficient is
127). But when the products are accumulated, the resulting sum can
overflow the 16 bit signed range. Instead of accumulating in 32 bit,
we accumulate the largest product (either index 3 or 4) last with a
saturated addition.

(The VP8 MC asm does something similar, but slightly simpler, by
accumulating each half of the filter separately. In the VP9 MC
filters, each half of the filter can also overflow though, so the
largest component has to be handled individually.)

Examples of relative speedup compared to the C version, from checkasm:
                       Cortex      A7     A8     A9    A53
vp9_avg4_neon:                   1.71   1.15   1.42   1.49
vp9_avg8_neon:                   2.51   3.63   3.14   2.58
vp9_avg16_neon:                  2.95   6.76   3.01   2.84
vp9_avg32_neon:                  3.29   6.64   2.85   3.00
vp9_avg64_neon:                  3.47   6.67   3.14   2.80
vp9_avg_8tap_smooth_4h_neon:     3.22   4.73   2.76   4.67
vp9_avg_8tap_smooth_4hv_neon:    3.67   4.76   3.28   4.71
vp9_avg_8tap_smooth_4v_neon:     5.52   7.60   4.60   6.31
vp9_avg_8tap_smooth_8h_neon:     6.22   9.04   5.12   9.32
vp9_avg_8tap_smooth_8hv_neon:    6.38   8.21   5.72   8.17
vp9_avg_8tap_smooth_8v_neon:     9.22  12.66   8.15  11.10
vp9_avg_8tap_smooth_64h_neon:    7.02  10.23   5.54  11.58
vp9_avg_8tap_smooth_64hv_neon:   6.76   9.46   5.93   9.40
vp9_avg_8tap_smooth_64v_neon:   10.76  14.13   9.46  13.37
vp9_put4_neon:                   1.11   1.47   1.00   1.21
vp9_put8_neon:                   1.23   2.17   1.94   1.48
vp9_put16_neon:                  1.63   4.02   1.73   1.97
vp9_put32_neon:                  1.56   4.92   2.00   1.96
vp9_put64_neon:                  2.10   5.28   2.03   2.35
vp9_put_8tap_smooth_4h_neon:     3.11   4.35   2.63   4.35
vp9_put_8tap_smooth_4hv_neon:    3.67   4.69   3.25   4.71
vp9_put_8tap_smooth_4v_neon:     5.45   7.27   4.49   6.52
vp9_put_8tap_smooth_8h_neon:     5.97   8.18   4.81   8.56
vp9_put_8tap_smooth_8hv_neon:    6.39   7.90   5.64   8.15
vp9_put_8tap_smooth_8v_neon:     9.03  11.84   8.07  11.51
vp9_put_8tap_smooth_64h_neon:    6.78   9.48   4.88  10.89
vp9_put_8tap_smooth_64hv_neon:   6.99   8.87   5.94   9.56
vp9_put_8tap_smooth_64v_neon:   10.69  13.30   9.43  14.34

For the larger 8tap filters, the speedup vs C code is around 5-14x.

This is significantly faster than libvpx's implementation of the same
functions, at least when comparing the put_8tap_smooth_64 functions
(compared to vpx_convolve8_horiz_neon and vpx_convolve8_vert_neon from
libvpx).

Absolute runtimes from checkasm:
                          Cortex      A7        A8        A9       A53
vp9_put_8tap_smooth_64h_neon:    20150.3   14489.4   19733.6   10863.7
libvpx vpx_convolve8_horiz_neon: 52623.3   19736.4   21907.7   25027.7

vp9_put_8tap_smooth_64v_neon:    14455.0   12303.9   13746.4    9628.9
libvpx vpx_convolve8_vert_neon:  42090.0   17706.2   17659.9   16941.2

Thus, on the A9, the horizontal filter is only marginally faster than
libvpx, while our version is significantly faster on the other cores,
and the vertical filter is significantly faster on all cores. The
difference is especially large on the A7.

The libvpx implementation does the accumulation in 32 bit, which
probably explains most of the differences.

Signed-off-by: Martin Storsjö <martin@martin.st>

This makes it match the pattern already used for VP8 MC functions.

This also makes the signature match ffmpeg's version of these
functions, easing porting of code in both directions.

Signed-off-by: Martin Storsjö <martin@martin.st>

Originally written by Ronald S. Bultje <rsbultje@gmail.com> and
Clément Bœsch <u@pkh.me>

Further contributions by:
Anton Khirnov <anton@khirnov.net>
Diego Biurrun <diego@biurrun.de>
Luca Barbato <lu_zero@gentoo.org>
Martin Storsjö <martin@martin.st>

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Signed-off-by: Anton Khirnov <anton@khirnov.net>