--- old/src/hotspot/share/gc/g1/g1HeapVerifier.hpp	2017-11-29 16:41:18.720793292 +0100
+++ new/src/hotspot/share/gc/g1/g1HeapVerifier.hpp	2017-11-29 16:41:18.476783647 +0100
@@ -43,12 +43,13 @@
 
 public:
   enum G1VerifyType {
-    G1VerifyYoung = 1,
-    G1VerifyMixed = 2,
-    G1VerifyRemark = 4,
-    G1VerifyCleanup = 8,
-    G1VerifyFull = 16,
-    G1VerifyAll = -1
+    G1VerifyYoungOnly   =  1, // -XX:VerifyGCType=young-only
+    G1VerifyInitialMark =  2, // -XX:VerifyGCType=initial-mark
+    G1VerifyMixed       =  4, // -XX:VerifyGCType=mixed
+    G1VerifyRemark      =  8, // -XX:VerifyGCType=remark
+    G1VerifyCleanup     = 16, // -XX:VerifyGCType=cleanup
+    G1VerifyFull        = 32, // -XX:VerifyGCType=full
+    G1VerifyAll         = -1
   };
 
   G1HeapVerifier(G1CollectedHeap* heap) : _g1h(heap), _enabled_verification_types(G1VerifyAll) { }