Comment by wk_end

2 days ago

> the CppInterOp approach to cpp interop is completely janky (no pun intended). the approach literally string munges cpp and then parses/interprets it to emit ABI compliant calls.

So, I agree that this sounds janky as heck. My question is: besides sounding janky as heck, is there something wrong with this? Is it slow/unreliable?

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wk_end

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almostgotcaught  2 days ago

i mean it's as prone to error as any other thing that relies on string munging. it's probably not that much slower than the alternative i proposed - because the trampolines/wrappers are jitted and then reused - but it's just not robust enough that i would ever imagine building a prod system on top of it (eg using cppyy in prod) let alone baking it into my language/runtime.

  • Jeaye  2 days ago

    > i mean it's as prone to error as any other thing that relies on string munging.

    This is misleading. Having done a great deal of both (as jank also supports C++ codegen as an alternative to IR), if the input is a fully analyzed AST, generating IR is significantly more error prone than generating C++. Why? Well, C++ is statically typed and one can enable warnings and errors for all sorts of issues. LLVM IR has a verifier, but it doesn't check that much. Handling references, pointers, closures, ABI issues, and so many more things ends up being a huge effort for IR.

    For example, want to access the `foo.bar` member of a struct? In IR, you'll need to access foo, which may require loading it if it's a reference. You'll need to calculate the offset to `bar`, using GEP. You'll need to then determine if you're returning a reference to `bar` or if a copy is happening. Referencing will require storing a pointer, whereas copying may involve a lot more code. If we're generating C++, though, we just take `foo` and add a `.bar`. The C++ compiler handles the rest and will tell us if we messed anything up.

    If you're going to hand wave and say anything that's building strings is error prone and unsafe, regardless of how richly typed and thoroughly analyzed the input is, the stance feels much less genuine.

  • refulgentis  2 days ago

    The delta between the title and the content gave me extreme pause, thanks for sharing that there's, uh, worse problems.

    I'm a bit surprised I've seen two articles about jank here the last 2 days if these are exemplars of the technical approach and communication style. Seems like that wouldn't be enough to get on people's radars.