No mention of msys2? They have a windows native clang http://repo.msys2.org/mingw/x86_64/
Also cygwin has a native version too
I agree, I’ve had really good results cross plaform code (Linux, Mac, Windows) with MingW64 w/ pthreads on Windows. I code to the C++11 standard though, not certain about support for newer standards. One other thimg that is important to me is ease of integration with the nvcc compiler for linking CUDA kernels - only certain compilers and versions are supported. The author’s use of the word “best” doesn’t seem to address that aspect.
After a multi-year effort chromium switched to Clang on Windows last year. They wrote about it and then differences in build size, build time, performance, etc:
Agner’s test results are on page 76 of Optimizing software in C++. He covers mostly optimizations from the 1986 Dragon Book and heavily emphasizes algebraic optimizations. Loop vectorization is not covered in detail. Loop nests are not mentioned.