Isn't that common knowledge in our field? When I attended Technical University, that was one of mandatory classes.
In case of LabVIEW, the compiler is LLVM. Meaning anyone who looked into clang also looked into that.
The amount of developers who looked into CLang or GCC isn't as small as you suggest. This is actually quite common, if a job requires that.
I used LLVM as well at some point, ie. I worked on optimizations performed on Intermediate Language tree. And it so happens that in "Heap Peek", you can look at that IL for any VI.