https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84234
--- Comment #6 from Florian Lemaitre <gcc.account at lemaitre dot re> --- I want auto-vectorization, not guided vectorization. Basically, I try to write a fast RSQRT that will not break auto vectorization, and this will be integrated in a large scale project where it is easy to tell people "use this function" than to make them writing guided vectorization. As far as I'm concerned, I'm completely fine with telling the compiler my function doesn't have any side effect. But this should be written somewhere for other people.