Not standard, unless you count "supported with the same semantics in multiple compilers" as good enough. They are not portable between CPU architectures either

Not standard, unless you count "supported with the same semantics in multiple compilers" as good enough. They are not portable between CPU architectures either way For reference, C got real alignment support in C11 and C++ in C++17. Without this, even starting on SIMD is risky. That said, you can go really far with a good C++ math library like Eigen which has singe vectorization in the operations themselves.