[stefanha]

> it's very easy for a runtime to use a zero-cost strategy to enforce that memory loads/stores are all in-bounds

I believe your statement is only true for wasm32 on a 64-bit host where guard pages can be placed around the memory.

Has anyone come up with a zero-cost strategy for wasm64?

This is something that CPU vendors could help with. x86 used to have segment registers but the limit checks were removed in x86_64 so FS/GS cannot be used for this purpose anymore.