>> Any instruction that can be similarly rephrased as a composition of more restricted elementary instructions is also a candidate for this macro-insn approach.

>> Any instruction that can be similarly rephrased as a composition of more restricted elementary instructions is also a candidate for this macro-insn approach. I really like the idea of composition or standard prefixes. My favorite is the idea of replacing cmp/branch with "if". Where the condition is a predicate for the following instruction. For RISC-V it would eat a large part of the 16bit opcodes. Some form of load/store might be a good use for the remaining 16bit ops. Other things that might be a good prefix could be encoding data types (8,16,32,64 bit, sign extended, float, double) or a source/destination register. It might be interesting to see how a full ISA might be decomposed into smaller instruction fragments.