| ▲ | Deegen: A JIT-Capable VM Generator for Dynamic Languages(arxiv.org) |
| 96 points by mpweiher a day ago | 16 comments |
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| ▲ | Rochus a day ago | parent | next [-] |
| Discussed here: https://news.ycombinator.com/item?id=42186507 |
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| ▲ | sitkack 19 hours ago | parent | prev | next [-] |
| > We implement LuaJIT Remake (LJR), a standard-compliant Lua 5.1 VM, using Deegen. Across 44 benchmarks, LJR's interpreter is on average 179% faster than the official PUC Lua interpreter, and 31% faster than LuaJIT's interpreter. LJR's baseline JIT has negligible startup delay, and its execution performance is on average 360% faster than PUC Lua and only 33% slower (but faster on 13/44 benchmarks) than LuaJIT's optimizing JIT. presentation by the author Deegen: A LLVM-based Compiler-Compiler for Dynamic Languages
https://www.youtube.com/watch?v=5cAUX9QPj4Y Slides https://aha.stanford.edu/sites/g/files/sbiybj20066/files/med... Ongoing work documented here https://sillycross.github.io/ and some comments here https://lobste.rs/s/ftsowh/building_baseline_jit_for_lua https://github.com/luajit-remake/luajit-remake |
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| ▲ | versteegen 16 hours ago | parent [-] | | My heart sank at the description of being LLVM based. (I couldn't think of a worse choice for creating a JIT compiler.) Thankfully, they don't use LLVM at runtime! LLVM is only for static compilation of the JIT. |
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| ▲ | maplant 14 hours ago | parent | prev | next [-] |
| Very cool! Taking copy and patch to its natural conclusion |
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| ▲ | bobajeff a day ago | parent | prev | next [-] |
| If this can generate a v8/spidermonkey class engine for new scripting languages that would be incredible. |
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| ▲ | tekknolagi a day ago | parent | prev | next [-] |
| It is very exciting to get a multi-tier VM from just bytecode encoded version of VM spec. |
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| ▲ | versteegen 15 hours ago | parent | next [-] | | Yes! I've been waiting for a practical tool like this, and would love to write a JIT for Squirrel/Quirrel using it. But I'm looking through the luajit-remake codebase, and there is still a lot of code. Assuming that the drt and deegen directories are Deegen (however, at lease drt/tvalue.h is clearly part of the VM, not of Deegen): > fd . -e h -e cpp | egrep -v "test|thirdparty|deegen|drt" | xargs wc --total=only --lines
34734
> fd . -e h -e cpp | egrep -v "test|thirdparty" | xargs wc --total=only --lines
97629
In comparison, Lua 5.2.4 is 20.3k lines of C and LuaJIT 1.1.5, which is a (comparable?) method JIT compiler, is 22.8k lines of C and 4.8k lines of Lua (for dynasm and JIT support). LuaJIT 2.1 is 74.9k lines of C, 13.7k Lua. | | |
| ▲ | vanderZwan 8 hours ago | parent [-] | | I think a large part of that might be the language they choose. Every C++ code example in the paper feels extremely verbose to me, and I wonder to which degree that is inherently required for encoding language semantics, and to which degree it's C++ syntax being noisy. This is not a critique of the authors, btw. Considering the breadth and depthtof various types of domain-specific knowledge that have to be "synthesized" on a project like this, developing a mastery of C++ is almost a given. So implementing things in C++ was likely the most natural approach for them. It technically also might be the most portable choice, since anyone who has LLVM installed will also have a C++ compiler. I do wonder what it would be like if this were built upon a language with more appropriate "ergonomics" though. Maybe they can invent and implement DSL for Deegen in Deegen, haha. |
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| ▲ | Rochus a day ago | parent | prev [-] | | See also https://stefan-marr.de/papers/oopsla-larose-et-al-ast-vs-byt... which demonstrates that we can do that with GraalVM/Truffle, and the generated VM from the AST based interpreter is even faster than the bytecode interpreter. | | |
| ▲ | tekknolagi 19 hours ago | parent [-] | | There is significant warmup required, which is not good for most programs. Deegen's approach is very promising for interactive use or other situations that require low latency. |
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| ▲ | taylorius 20 hours ago | parent | prev | next [-] |
| I wonder if this would work for python. |
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| ▲ | hinkley 18 hours ago | parent | prev [-] |
| I’m gonna need you to take about 15% off the top there, Squirelly Dan. |
