> Still, it’s somewhat surprising how easy it was to generate our ‘JIT’ interpreter — the code isn’t much bigger then the original version. Perhaps with some more scaffolding/helper libraries, this could be a viable way to create fast interpreters for new languages?
This is one of the many things that Terra excels at and is intended for: http://terralang.org/ I'm personally using it for dynarecing code in emulators now; works great.
So in short, this is basically a specialized transpiler (transpiling your bytecodes into high level Lua code) + a call to eval to evaluate the transpiled code using LuaJIT's JIT facility.
This seems like a fairly useful technique, provided the given bytecode file isn't terribly big (since you're uh...converting it into string representation), and that the bytecode isn't some run-once-throw-away code, otherwise you spend more time converting it into Lua code and JIT-ing it.
Having said that, I wonder if it'd be even less of a hassle by skipping the bytecode part. Just transpile the source written in your custom language straight into Lua code, and have that code JIT'ed instead. Many high level structures/information would be preserved, allowing JIT to do an even better job perhaps?
Yes; this could potentially be slow. If for example, you had an application that just had straight line code (no loops), and you were running it from the command line a million times you would end up hurting from this approach. Generating LuaJIT bytecode instead of source code would (I think) make this less of an issue.
In this case, the bytecode is what you start with :)
Going straight from a parse tree to Lua could work, but locks you into the possibly slow code-generation approach. Having an intermediate level (high level bytecode, or even an interpreter over the AST) would be more flexible -- you could choose when to switch over the compiled version.
> Still, it’s somewhat surprising how easy it was to generate our ‘JIT’ interpreter — the code isn’t much bigger then the original version. Perhaps with some more scaffolding/helper libraries, this could be a viable way to create fast interpreters for new languages?
This is one of the many things that Terra excels at and is intended for: http://terralang.org/ I'm personally using it for dynarecing code in emulators now; works great.