Function rustc_mir_transform::coverage::check_code_region

fn check_code_region(code_region: CodeRegion) -> Option<CodeRegion>

If llvm-cov sees a code region that is improperly ordered (end < start), it will immediately exit with a fatal error. To prevent that from happening, discard regions that are improperly ordered, or might be interpreted in a way that makes them improperly ordered.