classLoaderData.hpp is included by about 700 out of 1000 .o files in HotSpot. Most of these are transitively included through klass.hpp, typeArrayKlass.hpp and instanceKlass.hpp.

These headers can be refactored by moving inline functions that depend on ClassLoaderData to xxx.inline.hpp. This reduces the .o files that include classLoaderData.hpp to about 260.