https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59658
--- Comment #2 from Eric Gallager <egallager at gcc dot gnu.org> --- (In reply to Richard Biener from comment #1) > But it might be misleading (similar to -O0 vs -O2) - enabling for example > -ftree-pre won't enable PRE for -Og as it has a completely different > pass pipeline which is not based on -O[123]. Those enumerations are only > relevant for the 'numbered' optimization levels (excluding -O0). > > So we miss to filter options in --help optimizers that can be enabled at all. It's a place to start at least.
