Re:Write Your Own Virtual Machine
by astrobe_ on Saturday August 15, 2020 @08:18AM
(#24168336)
Technically, that's a bit off topic because this is about compilers and code generation, while a VM defines the basic semantics compilers work with.
For VMs, what is relevant is whether you implement an "inc (reg)" or not, that is if you choose to take the RISC path (small set of mostly orthogonal instructions) or the CISC path (lots of microcode, things like "repnz scasb" in x86 assembly or elaborate addressing schemes).
This actually somewhat a false dichotomy, as you can have a RISC-style instruction set plus a few "high level" instructions for things you expect to do a lot - like, for instance, array operators à la APL/J.
For VMs, what is relevant is whether you implement an "inc (reg)" or not, that is if you choose to take the RISC path (small set of mostly orthogonal instructions) or the CISC path (lots of microcode, things like "repnz scasb" in x86 assembly or elaborate addressing schemes).
This actually somewhat a false dichotomy, as you can have a RISC-style instruction set plus a few "high level" instructions for things you expect to do a lot - like, for instance, array operators à la APL/J.