> For example, say you want to pass a 16-byte struct as an argument: how do you do it? Do you store the struct in memory and pass an int32 pointer to its start address? Or an int64 pointer? Maybe you encode it as two int64s? Once you've made a choice, good luck calling functions generated by a compiler that made a different one!

Sounds like every architecture ever? There’s an architecture specification and then there’s an ABI. It’s common to only support some small number of sizes, x86 is a bit the odd one out these days.