https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116497
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- >When writing threaded code interpreters by chaining functions with musttail >the normal ABI behavior of some caller saved registers can cause unnecessary >spills and fills compared to using indirect goto. THIS is why I call all of this attribute usage a hack since it means you will always need to keep on changing the sources of the application rather than ever doing improvements to GCC that would help code that didn't even know about the attributes. The same is true of this whole musttail attribute. It does nothing except provide an error message. There are better ways of implementing that inside GCC really than the attribute that was added. GCC has -fopt-info which should have been used instead. Here is another place where the attribute is just a way to hack around instead of improving GCC for ABI for static functions.
