Zcb Extension

Zcb has simple code-size saving instructions which are easy to implement on all CPUs. All proposed encodings are currently reserved for all architectures, and have no conflicts with any existing extensions.

The Zcb extension depends on the Zca extension.

As shown on the individual instruction pages, many of the instructions in Zcb depend upon another extension being implemented. For example, c.mul is only implemented if M or Zmmul is implemented, and c.sext.b is only implemented if Zbb is implemented.