https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87400
--- Comment #3 from Richard Earnshaw <rearnsha at gcc dot gnu.org> --- (In reply to Alex Kalmuk from comment #2) > I write about mtpcs-frame for thumb, not mapcs-frame, I know the last one > for arm instruction set. The tpcs is also obsolete (the tpcs was replaced by the atpcs more than 20 years ago); the atpcs was superseded by the aapcs about 15 years ago now. I'm not sure why the tpcs-frame and tpcs-leaf-frame flags weren't removed from the compiler; they certainly doesn't do anything useful now. Unfortunately, the aapcs does not define a frame pointer or mandate a frame layout, which makes backtracing through a frame impossible. Any frame pointer used by the compiler can only be used within that frame.
