[astrange]

"Made up of" isn't helpful. All assembly languages are equivalent to a sequence of bit operations. (…if you ignore side effects and memory operations.)

In fact there's several different single operations you can build them all out of: https://en.wikipedia.org/wiki/One-instruction_set_computer#I...

So you take your assembly instructions, write a sufficiently good model of assembly instructions<>bit operations, write a cost model (byte size of the assembly works as a cheap one), and then search for assembly instructions that perform the equivalent operation and minimize the cost model.

Like here: https://theory.stanford.edu/~aiken/publications/papers/asplo...