pub fn mappings(&self) -> Vec<Mapping> {
        let mut mappings = vec![];
        for (name, entry) in self.intrinsics.iter() {
            if let Intrinsic::FunctionPointer(_, ptr) = *entry {
                mappings.push((CString::new(name.as_str()).unwrap(), ptr))
            }
        }
        mappings
    }
Returns value to function pointer mappings for non-builtin intrinsics.

Builtins are filtered out of this list.
weld/src/codegen/llvm2/intrinsic.rs