Yes, the C and C++ standards allow compilers to eliminate loops which have no side effects (It's actually slightly more tricky than this but whatever, check the spec for the exact details). This can be tough in situations like you say, but also in other places: for example, Rust's semantics do not allow you to elide them, but because we use LLVM, we incidentally inherited this behavior: https://github.com/rust-lang/rust/issues/28728

LLVM has since added a new intrinsic: https://reviews.llvm.org/D38336

This will allow us to fix the bug.