How many instructions do you need to successfully compile C code? Let’s see, you’d need some jump instructions, some arithmetic functions, and — of course — move instructions, right? Turns out you only need the move instruction, which — on x86, at least — is Turing complete.
While the effort is a bit tongue-in-cheek, we have to admit that if you were trying to create your own CPU, this would make for a simple architecture and might have power or complexity advantages, so maybe someone will find a practical use for it after all. If you wanted a C compiler for a simple CPU, this wouldn’t require much to emulate at a byte-code level, either.
How does it work? The best way to answer that is to look at the presentation slides on the GItHub site. Everything works through clever usage of memory locations and dummy addresses to do nothing. Efficient? Maybe not. But it does work.
For example, if you want to test to see if x and y are equal
mov [x],0mov [y],1mov R,[x]
That hides a lot of detail, of course, but the idea is that if Y doesn’t equal X, you’ll write a 1 to some random memory location (which better not be important; that’s one of the details). If X and Y are equal, you’ll overwrite with a 1. So R winds up with a 0 if X and Y are different or a 1 if they are the same.
In practical terms, if you want to translate something like “if (x==y) x=100” you wind up setti ..
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