Porting/ncnn

Finished

• Translate x86_64 SSE to ppc64le VSX intrinsics
• VSX toolchains: check for SSE2 support
• Add POWER8 VSX toolchains
• load_param_mem pybind
• test_squeezenet failed under Lubuntu 16.04 PowerPC 32-bit
• support big endian platform, add powerpc ci
• Update POWER Clang version docs

In progress

• Update Vulkan dependency docs
• CI missing for POWER9/Clang
• Replace SSE with native VSX

See Also

• chaiNNer
• ONNX
• PyTorch