Most compilers that target WebAssembly can also target asm.js, which is compatible with IE.
AFAIK it's more about missing stuff like DOM access and GC that stands in the way.
AFAIK it's more about missing stuff like DOM access and GC that stands in the way.
asm.js is different enough that it's just not about adding a seperate asmjs "compatibility" target. On the top of my head you don't have 64-bit ints or floats and I believe the way you call asm.js fns from/to JS is different from wasm. Adding asm.js support just for IE 11 wouldn't be worth the effort.