https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77728
--- Comment #21 from Jakub Jelinek <jakub at gcc dot gnu.org> --- inform, beyond being consistent with what i386 and rs6000 backends do here, has the advantage that it doesn't break the build even with -Werror, generally there is nothing wrong on the code we want to inform user about, so there is nothing to fix unless they want to achieve ABI compatibility with code compiled by older GCC versions. For this category i386/rs6000 backends use inform. There are also warning uses with OPT_Wpsabi, but those are there for when user is doing something considered wrong, e.g. passing vector argument by value in a function without corresponding ISA supporting those vectors enabled.
