luajit-remake VS plb2

It's really cool that Haoran Xu copy-and-patch technique is catching on, I remember discovering it through his blog posts on applying these techniques to his own LuaJIT remake project[0][1] (and I probably found those through a post here). I highly recommend them if you're into that sort of thing, BTW. They're incredible deep dives, but he uses the details-element to keep the metaphorical descents into Mariana Trench optional so it doesn't get too overwhelming.

I even had the privilege of congratulating him the 1000th star of the GH repo[2], where he reassured me and others that he's still working on it despite the long pause after the last blog post, and that this mainly has to do with behind-the-scenes rewrites that make no sense to publish in part.

[0] https://sillycross.github.io/2022/11/22/2022-11-22/

[1] https://sillycross.github.io/2023/05/12/2023-05-12/

[2] https://github.com/luajit-remake/luajit-remake/issues/11

This seems like an awesome way of writing faster interpreters – i.e. not in assembly, but in C++ snippets you stitch together with a tool.

I did peek at the deegen tool a bit, and it seems quite large? https://github.com/luajit-remake/luajit-remake/tree/master/d...

I would be interested in an overview of all the analysis it has to do, which as I understand is basically “automated Mike Pall”

FWIW I think this is the hand-written equivalent with LuaJIT’s dynasm tool: https://github.com/LuaJIT/LuaJIT/blob/v2.1/src/vm_x64.dasc (just under 5000 lines)

Also there are several of these files with no apparent sharing, as you would get with deegen:

https://github.com/LuaJIT/LuaJIT/blob/v2.1/src/vm_x86.dasc

https://github.com/LuaJIT/LuaJIT/blob/v2.1/src/vm_ppc.dasc

https://github.com/attractivechaos/plb2 - limited but broad comparison across a large number of languages. Swift and Nim both compare favourably to C.

https://github.com/attractivechaos/plb2/blob/master/README.m...

Synthetic benchmarks aside, I think as far as average (spring boots of the world) code goes, Go beats Java almost every time, often in less lines than the usual pom.xml

I wouldn't be so enthusiastic. Look at other languages that have JIT now: Ruby and PHP. After years of efforts, they are still an order of magnitude slower than V8 and even PyPy [1]. It seems to me that you need to design a JIT implementation from ground up to get good performance – V8, Dart, LuaJIT and PyPy are like this; if you start with a pure interpreter, it may be difficult to speed it up later.

[1] https://github.com/attractivechaos/plb2

A curious thing about Swift: after https://github.com/attractivechaos/plb2/pull/23, the matrix multiplication example is comparable to C and Rust. However, I don’t see a way to idiomatically optimise the sudoku example, whose main overhead is allocating several arrays each time solve() is called. Apparently, in Swift there is no such thing as static array allocation. That’s very unfortunate.