add support for Apple M1 and other arm64+Neon architectures

[cskiraly]

There was already some NEON support, through a separate code
path. This version relies on the sse2neon library to add
NEON support directly without a separate code path.

Signed-off-by: Csaba Kiraly [email protected]

[cskiraly]

Just linking original issue upstream to help those looking at it.
catid#18

[cskiraly]

Tested on:

• Apple M1 MacOS:

Parameters: [original count=1000] [recovery count=100] [buffer bytes=64000] [loss count=100] [random seed=2]
Leopard Encoder(64 MB in 1000 pieces, 100 losses): Input=3136.18 MB/s, Output=313.618 MB/s
Leopard Decoder(64 MB in 1000 pieces, 100 losses): Input=708.302 MB/s, Output=70.8302 MB/s

• Apple M1 under Parallels Linux arm64 VM (4 cores, openMP):

Parameters: [original count=1000] [recovery count=100] [buffer bytes=64000] [loss count=100] [random seed=2]
Leopard Encoder(64 MB in 1000 pieces, 100 losses): Input=5281.4 MB/s, Output=528.14 MB/s
Leopard Decoder(64 MB in 1000 pieces, 100 losses): Input=901.332 MB/s, Output=90.1332 MB/s

• Raspberry Pi 3:

Parameters: [original count=1000] [recovery count=100] [buffer bytes=64000] [loss count=100] [random seed=2]
Leopard Encoder(64 MB in 1000 pieces, 100 losses): Input=136.62 MB/s, Output=13.662 MB/s
Leopard Decoder(64 MB in 1000 pieces, 100 losses): Input=27.0177 MB/s, Output=2.70177 MB/s

• RK3328 (Rock64 SBC, 4 x Cortex-A53):

Parameters: [original count=1000] [recovery count=100] [buffer bytes=64000] [loss count=100] [random seed=2]
Leopard Encoder(64 MB in 1000 pieces, 100 losses): Input=202.632 MB/s, Output=20.2632 MB/s
Leopard Decoder(64 MB in 1000 pieces, 100 losses): Input=34.2045 MB/s, Output=3.42045 MB/s

[liamsi]

@cskiraly when you tested this on an Apple M1 under MacOS, did you just run cmake and then make using the generated Makefile? When I do this on my machine (m1 max with Monterey), I run into Undefined symbols for architecture arm64 🤔

[cskiraly]

@liamsi I was compiling it through our wrapper in https://github.com/status-im/nim-leopard
which disables openMP. It actually does
cmake .. -DCMAKE_BUILD_TYPE=Release -DENABLE_OPENMP=off

-DENABLE_OPENMP=off should work for you.

The undefined symbols I see when enabling openMP are omp symbols. Either there is something wrong with the linker args, or the omp installed by brew is not arm64, I have yet to check. We do have some related discussion at https://github.com/status-im/nim-leopard#openmp

[liamsi]

Thanks, -DENABLE_OPENMP=off does the trick. I made sure to use llvm/clang installed via brew but I still do see errors (this time related to std::). I'll continue playing around with different flags and see if I can get it compile with all optimizations. Will let you know.