Reverse the order of stack inputs for the store instructions.

[fredericomba]

The stack store instructions take arguments like this: [pointer, value]. However, if the arguments were in the order [value, pointer], it would be easier to use the store instructions with long data structures on the stack. Of course, making this change would break backwards compatibility, so a "reverse" or "swap" instruction that reverses the last two values on the stack could address this.

I can't elaborate on this point right now, but if you also faced this, you'll probably know what I'm talking about.

[yfzhe]

With the multi-value feature, you don't need the "reserve" or "swap" instruction but rather implement it as a function by yourself.

See: https://github.com/WebAssembly/multi-value/blob/master/proposals/multi-value/Overview.md#functions-with-multiple-return-values

[eqrion]

Changes to wasm must follow this process document, and generally starts as an issue on the WebAssembly/design repository, not in this repository.

We can't break backwards compatibility, so changing stack operand order is a non-starter. However stack manipulation instructions have been actively discussed before.

[tlively]

I think we can close this as a duplicate of WebAssembly/design#1381.