[rightbyte]

> Rather than "jumping into the middle of an instruction" (which to me implies some crazy trickery where both the original instruction and the middle of it do something useful, like the sibling comment about biology)

Doesn't "jumping into the middle of the instruction" just mean that decoding from the middle is another instruction, then when decoding from the start of it?

E.g.:

    IMUL -> 0x0FAF 
    SCASW -> 0xAF

[rep_lodsb]

Almost any random bytes can be decoded as some instruction - most of them are not useful. The essence of this jump-forward-by-one-or-two-bytes trick is that it performs an operation which doesn't have an effect on the program, so it can be considered to be a single-byte jump opcode, and its "immediate operand" as a separate instruction which is simply skipped over.

You could define assembler macros named something like "SKIP1" and "SKIP2" that emit these opcode bytes (3Ch / 3Dh), and use them just like a jump, provided that you don't care about the flags.

My point was that this is easier to reason about than the more general case where (working) code jumps into the middle of an instruction that already does something else - that either takes extreme cleverness, or evolution over millions of years.