Summary:
This PR contains below changes:
- Conform C++11
- [`faiss` is written in C++11](https://github.com/facebookresearch/faiss/blob/main/CONTRIBUTING.md#coding-style), but [`faiss/cppcontrib/SaDecodeKernels-avx2-inl.h`](442d9f4a2d/faiss/cppcontrib/SaDecodeKernels-avx2-inl.h) and [the test](442d9f4a2d/tests/test_cppcontrib_sa_decode.cpp) use some C++17 features. This PR rewrites these codes to make them independent to C++17.
- Enable AVX2 on `faiss_test`
- Currently `faiss_test` is compiled without `-mavx2` even if `-DFAISS_OPT_LEVEL=avx2` , so **`tests/test_cppcontrib_sa_decode.cpp` hasn't checked `faiss/cppcontrib/SaDecodeKernels-avx2-inl.h` at all** . This PR adds `-mavx2` to `faiss_test` if `-DFAISS_OPT_LEVEL=avx2` , so now `tests/test_cppcontrib_sa_decode.cpp` confirms `faiss/cppcontrib/SaDecodeKernels-avx2-inl.h` if `-DFAISS_OPT_LEVEL=avx2` , and does `faiss/cppcontrib/SaDecodeKernels-inl.h` if not `-DFAISS_OPT_LEVEL=avx2` .
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/2388
Reviewed By: mdouze
Differential Revision: D38005738
Pulled By: alexanderguzhva
fbshipit-source-id: b9319c585c6849e1c7a4782770f2d7ce8c0d8660
2952487f0e