vuo-compile vs Clang/LLVM versions

Discussions
1

Hi folks,

I’ve been reading about Developing a Library Module, from which I learned that

If your library module is written in another language, you can compile it with Clang.

If I follow those instructions using the Clang supplied by Apple’s XCode Command-Line Tools (Apple LLVM version 10.0.1 (clang-1001.0.46.4) Target: x86_64-apple-darwin18.7.0), my composition won’t run, and I find the following error in the Console:

loadModule():1763 Error: Couldn’t parse module ‘my.test_lib.bc’: Unknown bitstream version!.

As far as I can tell by inspecting the LLVM source code, this is about the MODULE_CODE_VERSION record in the bitcode file. But according to the historical documentation, the last time a new bitstream version was introduced was between LLVM 4.0.1 and LLVM 5.0.

I can’t find any command-line switches to tell Clang to emit earlier versions of bitcode, which is unsurprising because LLVM documentation does warn that bitcode is not intended to be used as a storage format or expected to be compatible between compiler releases.

Is vuo-compile really still based on a Clang/LLVM from 2017? What’s the best way to discover which version it was built with?

Thanks,
George

2

Hi, George. Great that you’re delving into the deeper parts of the API.

In fact, Vuo’s LLVM version is even older than that: LLVM 3.3. (You can see the versions of all of Vuo’s dependencies here: vuo/conanfile.py at main · vuo/vuo · GitHub .)

You can use the clang executable bundled with Vuo to compile your library module to compatible bitcode — Vuo.app/Contents/Frameworks/Vuo.framework/Helpers/clang

Updating LLVM is on my to-do list for the next few months. We had been postponing the update so that we could prioritize features that provide a more tangible benefit to the community. However, it’s getting to the point where we do need to update LLVM to help with other features, so it’s now a high priority.