If WASM and JVM Bytecode have a goto, then the compiler can use it.
Anyway, if you've never read that paper i linked to above, i do believe you'll find it mind-blowingly cool stuff. not kidding.
WASM's version of a goto is a branch, it is constrained to a limited scope. This creates a problem for general tail call elimination but not for auto-recursive functions.
Auto-recursive functions can switch to using a branch or using another loop construct, and the compiler can generate that WASM code. The control structures available are described in the link below. Mutually recursive functions where only one is meant as the entry point could be similarly converted into WASM instructions but where the additional functions are, essentially, eliminated and inlined into the original caller (this may not be a good general solution, though). But general tail calls cannot be converted into gotos as you might with a more conventional assembly language since WASM branches cannot go to arbitrary instruction addresses.
The problem is that in a conventional assembly language, if you do TCE then the goto would go to (har har) the same (or nearly the same) point as a regular function call (maybe it skips the first few instructions depending on the calling conventions involved). With TCE and WASM you'd have to, essentially, inline the called function, or a variant of it, in order to be able to branch to the start of it. You cannot branch into a different function or to the start of a different function, you have to call the other function and then you have a single entry point. Which, in WASM as currently specified, means you have to use the current calling conventions which does not permit TCE.
Edit: I should say, they don't have anything equivalent that can jump out of the method you are in.
Edit2: This is a bit more clear if you consider what it means for JVM bytecode to have a "return" set of instructions. Why does the bytecode need a return, if that is all managed by code that the compiler should handle anyway? You can look at the instructions here: https://en.wikipedia.org/wiki/List_of_Java_bytecode_instruct.... Note that it is the "jsr" instructions that let you do the equivalent of a long jump, and those specifically manipulate the stack. There is a "goto", but it is not valid to have that jump outside of the subroutine you are in.
