MSVC can't optimize it out and even keeps an external call to CRT
function rintf: https://godbolt.org/z/Ex9vjf8vj
It does translate to a real speedup on windows on some scenes, here are the ratios I had on my 13900K:
classroom 101.53%
junkshop 100.71%
monster 100.76%
attic 107.98%
bistro 113.00%
Pull Request: https://projects.blender.org/blender/blender/pulls/107371
252b0a023e