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Sounds like you want to compile a functional language. The best tutorial (in terms of being self-contained and being understandable in entirety) I've seen to co

Sounds like you want to compile a functional language. The best tutorial (in terms of being self-contained and being understandable in entirety) I've seen to compile FP to C is[0], I'd imagine that retargeting to LLVM wouldn't be that difficult either. [0] https://github.com/jozefg/pcf https://github.com/jozefg/pcf

arcticbull 6y ago
That’s a great idea honestly. Even Rust would make a good compile target, the strong typing could help debug the compiler as you go. Although LLVM assembly is a good choice too!
worldsayshi 6y ago
Are there any big downsides to compiling to C instead of LLVM? I would assume that it would be less performant but it feels like a shallow preconception.
- arc-in-space 6y ago
  It's somewhat more constricting, certain types of compiler magic are hard to reproduce in plain C. For instance, dealing with things that need to be stack-aware, such as a GC or tail recursion, takes epic hacks like the Boehm GC or the "Cheney on the MTA" trick. You're also stuck with the C calling convention. Plus, while generating C is simple, you're entirely on your own. With LLVM IR, you benefit from its infrastructure, the optimization passes and other LLVM-based tools, so you don't need to reinvent the wheel as much. In the end, you'll need some kind of IR anyway, and LLVM is a good place to start.
- jcranmer 6y ago
  > Are there any big downsides to compiling to C instead of LLVM? Well, for starters, you have to import all of C's undefined behavior, so it would be basically impossible to implement, e.g., 2's complement signed integer arithmetic.
  - badsectoracula 6y ago
    Strictly speaking it isn't impossible, just much slower since you'd have to implement on software what the hardware does. In practice though pretty much every compiler that uses that as an optimization has a flag to disable it and chances are you'll be needing to use other system and/or compiler specific stuff anyway.
ashton314 6y ago
This looks great! I’m taking a different approach than this compiler, but this looks like a good resource. Thanks!

arcticbull 6y ago

That’s a great idea honestly. Even Rust would make a good compile target, the strong typing could help debug the compiler as you go. Although LLVM assembly is a good choice too!

worldsayshi 6y ago

Are there any big downsides to compiling to C instead of LLVM? I would assume that it would be less performant but it feels like a shallow preconception.

arc-in-space 6y ago
It's somewhat more constricting, certain types of compiler magic are hard to reproduce in plain C. For instance, dealing with things that need to be stack-aware, such as a GC or tail recursion, takes epic hacks like the Boehm GC or the "Cheney on the MTA" trick. You're also stuck with the C calling convention. Plus, while generating C is simple, you're entirely on your own. With LLVM IR, you benefit from its infrastructure, the optimization passes and other LLVM-based tools, so you don't need to reinvent the wheel as much. In the end, you'll need some kind of IR anyway, and LLVM is a good place to start.
jcranmer 6y ago
> Are there any big downsides to compiling to C instead of LLVM? Well, for starters, you have to import all of C's undefined behavior, so it would be basically impossible to implement, e.g., 2's complement signed integer arithmetic.
- badsectoracula 6y ago
  Strictly speaking it isn't impossible, just much slower since you'd have to implement on software what the hardware does. In practice though pretty much every compiler that uses that as an optimization has a flag to disable it and chances are you'll be needing to use other system and/or compiler specific stuff anyway.

ashton314 6y ago

This looks great! I’m taking a different approach than this compiler, but this looks like a good resource. Thanks!