Now the g1HRPrinter (that is used when -Xlog:gc+region=trace is enabled) prints different data for heap regions depending on the action. It always print bottom, sometimes top and sometimes end. Would be good to always print the same format. This is what it looks like now:

[2,412s][trace ][gc,region] G1HR ALLOC(Eden) 0x00000005cac00000
[2,462s][trace ][gc,region] GC(6) G1HR CSET 0x00000005cac00000
[2,463s][trace ][gc,region] GC(6) G1HR CSET 0x00000005ca800000
[2,463s][trace ][gc,region] GC(6) G1HR REUSE 0x00000005cae00000
[2,464s][trace ][gc,region] GC(6) G1HR ALLOC(Survivor) 0x00000005caa00000
[2,507s][trace ][gc,region] GC(6) G1HR RETIRE 0x00000005caa00000 0x00000005cabb0e30
[2,507s][trace ][gc,region] GC(6) G1HR RETIRE 0x00000005cae00000 0x00000005caff7000
[2,509s][trace ][gc,region] GC(6) G1HR COMMIT [0x00000005cb000000,0x00000005cb200000]

Would also be good to get the typestring from the heapRegion.