Hacker News Reader

Comment by gosukiwi | Hacker News Reader

LLVM is one impressive (and scary) piece of technology.

FWIW this particular optimization has been in GCC for about 15 years, though it was only enabled by default in GCC 8. It's not rocket science.

Idk, not learning compiler theory is one of my regrets from school and this does seem like rocket science to me.

There are a ton of great books out there! If you're looking for a bit of the whole shebang, check out Compilers: Principles, Techniques, and Tools (aka, The Dragon Book). It's an older book, but a lot of what is described in there is still very relevant and good info. If you want a more high level overview at first, I'd recommend Crafting Interpreters [0] and Writing a Compiler/Interpreter in Go [1]. The latter two focus more on lexing, parsing, and intermediate code generation.

[0] https://craftinginterpreters.com/ [1] https://compilerbook.com/

I know I should get to it - maybe I should've done that during the COVID lockdown eh? Thanks for the links, I'll check them out.

Commenters elsewhere in the thread are saying this optimization existed in LLVM as well, just that this is a more deep/efficient version of it.

Yes, I'm referring to this particular version.

Impressive, sure. But curious what makes it scary to you?

The LLVM way of doing C++ is basically a wet dream when it comes to C++-isms e.g. not many C++ projects do their own dynamic casts and get away with it.

LLVM is fairly well-structured, especially compared to GCC. I don't find it scary but it is a big fat fucker of a codebase.

All dyn_cast does is move runtime polymorphism to compile time polymorphism.

OWL and MFC come to mind.

Reply on news.ycombinator.com