--- a/src/hotspot/share/gc/shared/weakProcessorPhases.hpp	Wed Aug 21 16:19:17 2019 -0400
+++ b/src/hotspot/share/gc/shared/weakProcessorPhases.hpp	Wed Aug 21 18:42:30 2019 -0400
@@ -25,6 +25,7 @@
 #ifndef SHARE_GC_SHARED_WEAKPROCESSORPHASES_HPP
 #define SHARE_GC_SHARED_WEAKPROCESSORPHASES_HPP
 
+#include "gc/shared/oopStorageSet.hpp"
 #include "memory/allocation.hpp"
 #include "utilities/globalDefinitions.hpp"
 #include "utilities/macros.hpp"
@@ -35,54 +36,117 @@
 
 class WeakProcessorPhases : AllStatic {
 public:
+  class Iterator;
+
   typedef void (*Processor)(BoolObjectClosure*, OopClosure*);
 
   enum Phase {
     // Serial phases.
-    JVMTI_ONLY(jvmti COMMA)
-    JFR_ONLY(jfr COMMA)
+    JVMTI_ONLY(jvmti JFR_ONLY(COMMA))
+    JFR_ONLY(jfr)
 
-    // OopStorage phases.
-    jni,
-    stringtable,
-    resolved_method_table,
-    vm
+    // Additional implicit phase values follow for oopstorages.
   };
 
   static const uint serial_phase_start = 0;
-  static const uint serial_phase_count = jni;
-  static const uint oop_storage_phase_start = serial_phase_count;
-  static const uint oop_storage_phase_count = (vm + 1) - oop_storage_phase_start;
-  static const uint phase_count = serial_phase_count + oop_storage_phase_count;
+  static const uint serial_phase_count = 0 JVMTI_ONLY(+ 1) JFR_ONLY(+ 1);
+  static const uint oopstorage_phase_start = serial_phase_count;
+  static const uint oopstorage_phase_count = OopStorageSet::weak_count;
+  static const uint phase_count = serial_phase_count + oopstorage_phase_count;
+
+  // Precondition: value < serial_phase_count
+  static Phase serial_phase(uint value);
 
-  static Phase phase(uint value);
-  static uint index(Phase phase);
+  // Precondition: value < oopstorage_phase_count
+  static Phase oopstorage_phase(uint value);
+
   // Indexes relative to the corresponding phase_start constant.
+  // Precondition: is_serial(phase) or is_oopstorage(phase) accordingly
   static uint serial_index(Phase phase);
-  static uint oop_storage_index(Phase phase);
+  static uint oopstorage_index(Phase phase);
 
   static bool is_serial(Phase phase);
-  static bool is_oop_storage(Phase phase);
+  static bool is_oopstorage(Phase phase);
 
+  static Iterator serial_iterator();
+  static Iterator oopstorage_iterator();
+
+  // Precondition: is_serial(phase)
   static const char* description(Phase phase);
-  static Processor processor(Phase phase); // Precondition: is_serial(phase)
-  static OopStorage* oop_storage(Phase phase); // Precondition: is_oop_storage(phase)
 
-  static bool is_stringtable(Phase phase);
-  static bool is_resolved_method_table(Phase phase);
+  // Precondition: is_serial(phase)
+  static Processor processor(Phase phase);
 };
 
 typedef WeakProcessorPhases::Phase WeakProcessorPhase;
 
-#define FOR_EACH_WEAK_PROCESSOR_PHASE(P)                                \
-  for (WeakProcessorPhase P = static_cast<WeakProcessorPhase>(0);       \
-       static_cast<uint>(P) <  WeakProcessorPhases::phase_count;        \
-       P = static_cast<WeakProcessorPhase>(static_cast<uint>(P) + 1))
+class WeakProcessorPhases::Iterator {
+  friend class WeakProcessorPhases;
+
+  uint _index;
+  uint _limit;
+
+  Iterator(uint index, uint limit) : _index(index), _limit(limit) {}
+
+  static const uint singular_value = UINT_MAX;
+  void verify_nonsingular() const NOT_DEBUG_RETURN;
+  void verify_category_match(const Iterator& other) const NOT_DEBUG_RETURN;
+  void verify_dereferenceable() const NOT_DEBUG_RETURN;
+
+public:
+  // Construct a singular iterator for later assignment.  The only valid
+  // operations are destruction and assignment.
+  Iterator() : _index(singular_value), _limit(singular_value) {}
+
+  bool is_end() const {
+    verify_nonsingular();
+    return _index == _limit;
+  }
+
+  bool operator==(const Iterator& other) const {
+    verify_category_match(other);
+    return _index == other._index;
+  }
+
+  bool operator!=(const Iterator& other) const {
+    return !operator==(other);
+  }
 
-#define FOR_EACH_WEAK_PROCESSOR_OOP_STORAGE_PHASE(P)                    \
-  for (WeakProcessorPhase P = static_cast<WeakProcessorPhase>(WeakProcessorPhases::oop_storage_phase_start); \
-       static_cast<uint>(P) < (WeakProcessorPhases::oop_storage_phase_start + \
-                               WeakProcessorPhases::oop_storage_phase_count); \
-       P = static_cast<WeakProcessorPhase>(static_cast<uint>(P) + 1))
+  Phase operator*() const {
+    verify_dereferenceable();
+    return static_cast<Phase>(_index);
+  }
+
+  // Phase doesn't have members, so no operator->().
+
+  Iterator& operator++() {
+    verify_dereferenceable();
+    ++_index;
+    return *this;
+  }
+
+  Iterator operator++(int) {
+    verify_dereferenceable();
+    return Iterator(_index++, _limit);
+  }
+
+  Iterator begin() const {
+    verify_nonsingular();
+    return *this;
+  }
+
+  Iterator end() const {
+    verify_nonsingular();
+    return Iterator(_limit, _limit);
+  }
+};
+
+inline WeakProcessorPhases::Iterator WeakProcessorPhases::serial_iterator() {
+  return Iterator(serial_phase_start, serial_phase_start + serial_phase_count);
+}
+
+inline WeakProcessorPhases::Iterator WeakProcessorPhases::oopstorage_iterator() {
+  return Iterator(oopstorage_phase_start, oopstorage_phase_start + oopstorage_phase_count);
+}
 
 #endif // SHARE_GC_SHARED_WEAKPROCESSORPHASES_HPP