If you're using GraalVM already, I think Sulong might be better -- my experience with WASM (for C) is that there's a bevy of POSIX-correct-but-ANSI-incorrect tricks that don't work properly on WASM. Debugging is also much nicer with LLVM IR (worst-case, just compile it to a binary and gdb that) than WASM (Firefox doesn't show the stack, Chrome has sourcemap bugs).