[Bug tree-optimization/109029] __builtin_signbit for 64bit fp does not vectorize

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109029

--- Comment #4 from Hongtao.liu <crazylht at gmail dot com> ---
Also found a document missing for signbitm2 in md.texi.