https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89073
Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- It is documented. https://gcc.gnu.org/onlinedocs/gcc-8.2.0/gcc/x86-Options.html#x86-Options documents -msha and says: These switches enable the use of instructions in the ... , SHA, ... instruction sets. Each has a corresponding -mno- option to disable use of these instructions. All the ISA selection options without -m are accepted in target, there are dozens of options not listed in the spot you are referring.