Function generate_covfun_record

fn generate_covfun_record(
    cx: &CodegenCx<'_, '_>,
    mangled_function_name: &str,
    source_hash: u64,
    filenames_ref: u64,
    coverage_mapping_buffer: Vec<u8>,
    is_used: bool,
)

Generates the contents of the covfun record for this function, which contains the function’s coverage mapping data. The record is then stored as a global variable in the __llvm_covfun section.