If your source language has some construct that you want to express as state machines (e.g. async, CPS, pattern match compilation), and you want to compile the state machine as direct threaded code[0] (which involves fewer branches than a while-switch), then if you're compiling to C, you need computed gotos[1], which are non-standard.
[0]: https://en.wikipedia.org/wiki/Threaded_code#Direct_threading [1]: https://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html