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by gergo_barany
719 days ago
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C has had fixed-size integers since C99: https://en.m.wikibooks.org/wiki/C_Programming/inttypes.h Targeting LLVM IR has the drawback that it is not platform independent: Details of calling conventions must be modeled in the IR, so the compiler must know what ABI it is targeting and emit the appropriate code. Compiling to C doesn't have this problem, since the C compiler will handle calling conventions for you. That said, LLVM would indeed have some advantages. Scheme has guaranteed tail call optimization, which you cannot guarantee with C. But LLVM does allow you to annotate calls as tail calls, and it can transform tail self-recursion into a loop for you. |
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Good point! You don't tend to see them too much in the wild, but they're available, which is good enough for present purposes.
> Targeting LLVM IR has the drawback that it is not platform independent: Details of calling conventions must be modeled in the IR, so the compiler must know what ABI it is targeting and emit the appropriate code. Compiling to C doesn't have this problem, since the C compiler will handle calling conventions for you.
Ooft, that would be a rough one. It kind of seems like there'd be some benefit to a low-level IR that's neither platform / implementation-specific, nor has the warts of C, but I appreciate that'd be well outside the scope of this project.
> That said, LLVM would indeed have some advantages. Scheme has guaranteed tail call optimization, which you cannot guarantee with C. But LLVM does allow you to annotate calls as tail calls, and it can transform tail self-recursion into a loop for you.
I suppose this will need be handled manually in the Pre-Scheme transpiler itself. Losing TCO seems like it ought to be a non-starter for anything Scheme-like.