We emit most functions in COMDAT sections, but with LLVM 3.9 we loose out on some optimizations:
http://llvm.org/releases/3.9.0/docs/ReleaseNotes.html#changes-to-llvm-s-ipo-model

Don't know what the impact will be.
(I've always disliked putting everything in COMDAT sections, so it's extra ammunition against that)

-Johan

Maybe compile to llvm IR, remove comdat attributes and compare assembler output?

https://llvm.org/bugs/show_bug.cgi?id=26774 uh, I don't think one can do such optimizations on public functions.