4 develop options defined, but not used:
ClearInterpreterLocals
G1ConcMarkForceOverflow
HeapDumpSegmentSize
TraceMetadataChunkAllocation

1) ClearInterpreterLocals was mentioned in src/cpu/sparc/vm/cppInterpreter_sparc.cpp and src/cpu/ppc/vm/cppInterpreter_ppc.cpp. Code for this option removed by JDK-8074457 "Remove the non-Zero CPP Interpreter" and JDK-8145528 "PPC64: Remove cpp interpreter implementation - part II"

2) G1ConcMarkForceOverflow was mentioned in g1/concurrentMark.cpp.
Code for this option removed by JDK-8139922 "Get rid of dead code in ConcurrentMark"

3) HeapDumpSegmentSize was mentioned in src/share/vm/services/heapDumper.cpp. Code for this option removed by JDK-8144732 "VM_HeapDumper hits assert with bad dump_len"

4) TraceMetadataChunkAllocation was mentioned in src/share/vm/memory/metaspace.cpp. Using of flag removed by JDK-8145092 "Use Unified Logging for the GC logging"