NCG: slight waste of time and space for inter-module data references (Darwin/PIC)

In GHC.CmmToAsm.PIC there is the following code:

howToAccessLabel config arch OSDarwin DataReference lbl
        -- data access to a dynamic library goes via a symbol pointer
        | labelDynamic config lbl
        = AccessViaSymbolPtr

        -- when generating PIC code, all cross-module data references must
        -- must go via a symbol pointer, too, because the assembler
        -- cannot generate code for a label difference where one
        -- label is undefined. Doesn't apply t x86_64.
        -- Unfortunately, we don't know whether it's cross-module,
        -- so we do it for all externally visible labels.
        -- This is a slight waste of time and space, but otherwise
        -- we'd need to pass the current Module all the way in to
        -- this function.
        | arch /= ArchX86_64
        , ncgPIC config && externallyVisibleCLabel lbl
        = AccessViaSymbolPtr

According to the comment, we could do better codegen if we had the current module. But we do! (in ncgThisModule config)