g1CollectedHeap.inline.hpp and g1ConcurrentMark.inline.hpp have a circular dependency. This causes the generated object files much larger than necessary and slows down the time to build. It also makes it difficult to use objdump to inspect the generated object files.

Use the following command to get the size of the generated object files:
$ du -ch hotspot/variant-server/libjvm/objs/g1*.o | tail -n 1

Currently:
6.1MB

After the patch:
3.7MB

Reduction of size for libjvm.so: 22144344 -> 22126016

(The above result is based on GCC 7.3.0 and configure options "--with-stdc++lib=static --disable-precompiled-headers --enable-unlimited-crypto --disable-keep-packaged-modules --with-native-debug-symbols=none --disable-warnings-as-errors --with-debug-level=release")