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Ask HN: Lighter alternatives to LLVM

by stealthcat on 11/30/22, 4:07 PM with 10 comments

Is it the only way to produce fast cross-platform binaries? LLVM is huge and compile times can be slow.

I found several compilers related:

0. GCC

1. Zig started as LLVM frontend, finally with self-hosting, can do cross-platform codegen without LLVM.

  • by cstrahan on 11/30/22, 6:23 PM

    See QBE: https://c9x.me/compile/

    > QBE is a compiler backend that aims to provide 70% of the performance of industrial optimizing compilers in 10% of the code. QBE fosters language innovation by offering a compact user-friendly and performant backend. The size limit constrains QBE to focus on the essential and prevents embarking on a never-ending path of diminishing returns.

    > The current version of QBE can target amd64 (linux and osx), arm64, and riscv64.

    "QBE vs. LLVM": https://news.ycombinator.com/item?id=25273907

  • by albinahlback on 11/30/22, 6:06 PM

    I presume you compile C/C++ code. How does your file structure look like? Do you have a lot of files with little to no content? You can speed things up by merging files. I have managed to reduce the building speed by around 95% by doing such simple things.

    Reducing the amount of unnecessary headers is also beneficial, but in comparison to merging files it barely makes a difference.

  • by TUSF on 11/30/22, 7:25 PM

    The Go compiler doesn't use LLVM. They pretty much built all their codegen for every platform from the ground up. But that's only possible because they have the resources to do that. As far as I know, the only viable alternative to LLVM, is GCC, which I don't think is "lighter".

    Also, Zig still uses LLVM. It's just that because LLVM is C++, the Stage 1 compiler had to be in C++ as well, and they've since slimmed it down by having LLVM expose a C API that the (now "self-hosted") Zig compiler can directly talk to instead.

  • by JonChesterfield on 11/30/22, 9:20 PM

    Libfirm and cranelift are vaguely similar ideas, not yet mentioned here

  • by marssaxman on 12/2/22, 3:50 PM

    LLVM really is the tail that wags the dog for smaller compiler projects.

    In addition to QBE as many have suggested, you might take a look at AsmJit, if you are using C++.

  • by gavinray on 11/30/22, 6:25 PM

    I'd say QBE probably

  • by tester756 on 11/30/22, 6:54 PM

    That's interesting question

    We definitely need to see some modern alternatives

  • by hulitu on 12/2/22, 10:40 PM

    GCC.