https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96125
--- Comment #3 from Peter Bergner <bergner at gcc dot gnu.org> --- Actually, it's more complicated than that. We only initialize the target builtins once, using the command line option values and not again using the target attribute/pragma values. That means we basically have to initialize the builtins, even if TARGET_MMA is false, just in case the user uses a target attribute/pragma that allows them. Will fixed a similar issue in March (no bugzilla entry for it though): https://gcc.gnu.org/pipermail/gcc-patches/2020-March/542555.html ...which basically just always enables the builtins. I'll do something similar.