I am glad i still build my public releases for Windows with ITK-4.13 and VS 2013. Not yet sure which flag is responsible for BMI2 instructions, but AVX2 is enough to make big problems, ITK5 build system on Windows forces to use AVX2 and runs test program on build host, but the test is useless for public releases. AVX2 was available on AMD hardware from Q2 2015. I definitely don’t want this in public release, too early, sorry. I don’t have very many users, but even if the number is small i don’t want upset some of them, who bought their hardware 3 years ago. Sorry.
Edit: were interesting to see where in ITK the appropriate intrinsic functions are used. Just enabling SSE2/3/AVX or whatever SIMD may do nothing, performance gain may be zero, i would not wonder. I shall check…
Edit:
Current hardware data from Steam (August 2019)
SSE2 100.00%
SSE3 100.00%
SSSE3 97.70%
SSE4.1 96.54%
SSE4.2 95.49%
AVX 89.29%