Add more details on the proposal.

[brendandahl]

No description provided.

[rossberg]

In addition to the editorial tweaks/corrections below, I would suggest two changes to the binary format:

• Bit 6 and 4 are closely related, in that they control the target for the operation. Can we move them together, i.e., use bit 5 instead of 4? Then we can more easily read them as a single two-bit value and extend its interpretation in the future (e.g., by using the combination 11 for another form of target, such as first-class memories).
• Memory index and type index are mutually exclusive, have the same format, and take similar roles. It would make sense to put them in the same position in the binary format. That would also simplify decoding (you parse an index unless both bits 4 and 6 are zero).

[brendandahl]

Thanks for the review!

In addition to the editorial tweaks/corrections below, I would suggest two changes to the binary format:

• Bit 6 and 4 are closely related, in that they control the target for the operation. Can we move them together, i.e., use bit 5 instead of 4? Then we can more easily read them as a single two-bit value and extend its interpretation in the future (e.g., by using the combination 11 for another form of target, such as first-class memories).

Bit 5 is currently used in the relaxed atomics proposal. We could potentially swap with them if you feel strongly about this.

[rossberg]

Yeah, given that both proposals are in early stages, I assume it's not a big deal to switch the bits. I think it would be worthwhile.