multi-memory

There are stray references to the concept of multiple address spaces (or 'memories') in the wasm spec at present, and I recall at one point you may have always been passing 'memory #0' to your load/store opcodes before it was dropped from 1.0. It looks like people are still working on that as the solution. https://github.com/WebAssembly/multi-memory > Add a memory index to all memory-related instructions. > Loads and stores have the memop field, in which we can allocate a bit indicating a memory index immediate in the binary format. > All other memory instruction already have a memory index immediate (which currently has to be 0).

It's not segmented, so no... or rather, not yet. The wasm spec already accommodates to some extent the notion of multiple "memories" (i.e. distinct flat heaps), although it only allows for one in practice: https://webassembly.github.io/spec/core/syntax/modules.html#... And there's an active proposal to allow for multiple memories: https://github.com/WebAssembly/multi-memory/blob/main/propos... In an environment like that, you'd need full-fledged pointers to carry both the memory index and the offset; and then you might want a non-fat "pointer to same memory" alternative for perf. Might as well call them far and near.

The multi-memory proposal is your best bet for this: https://github.com/WebAssembly/multi-memory It's supported in Wasmtime, WAVM, and WABT and wasm2c, and not much else so far (https://webassembly.org/roadmap/).