There are several large inline functions in vm_version_x86.hpp that are used only by vm_version_x86.cpp. E.g., feature_flags()

https://github.com/openjdk/jdk/blob/e7795851d2e02389e63950fef939084b18ec4bfb/src/hotspot/cpu/x86/vm_version_x86.hpp#L539

These should be moved to vm_version_x86.cpp to improve C++ build speed.