Agreed. The entire point of asm.js (which WASM is currently just a compact encoding of) is that it's a simpler subset of javascript that's easier to optimize. I

Agreed. The entire point of asm.js (which WASM is currently just a compact encoding of) is that it's a simpler subset of javascript that's easier to optimize. If you could transform arbitrary Javascript into asm.js efficiently, then similarly you could also apply asm.js's optimizations to arbitrary Javascript, and the whole asm.js part would be pointless.