8240590: Add MemRegion::destroy_array to complement introduced create_array

Reviewed-by: lkorinth, sjohanss

src/hotspot/share/gc/g1/g1ConcurrentMark.cpp

@@ -269,7 +269,7 @@ G1CMRootMemRegions::G1CMRootMemRegions(uint const max_regions) :
     _should_abort(false) { }
 
 G1CMRootMemRegions::~G1CMRootMemRegions() {
-  FREE_C_HEAP_ARRAY(MemRegion, _root_regions);
+  MemRegion::destroy_array(_root_regions, _max_regions);
 }
 
 void G1CMRootMemRegions::reset() {

src/hotspot/share/gc/shared/cardTable.cpp

@@ -62,8 +62,8 @@ CardTable::CardTable(MemRegion whole_heap, bool conc_scan) :
 }
 
 CardTable::~CardTable() {
-  FREE_C_HEAP_ARRAY(MemRegion, _covered);
-  FREE_C_HEAP_ARRAY(MemRegion, _committed);
+  MemRegion::destroy_array(_covered, _max_covered_regions);
+  MemRegion::destroy_array(_committed, _max_covered_regions);
 }
 
 void CardTable::initialize() {

src/hotspot/share/memory/filemap.cpp

@@ -1782,10 +1782,11 @@ bool FileMapInfo::map_heap_data(MemRegion **heap_mem, int first,
 
   struct Cleanup {
     MemRegion* _regions;
+    uint _length;
     bool _aborted;
-    Cleanup(MemRegion* regions) : _regions(regions), _aborted(true) { }
-    ~Cleanup() { if (_aborted) { FREE_C_HEAP_ARRAY(MemRegion, _regions); } }
-  } cleanup(regions);
+    Cleanup(MemRegion* regions, uint length) : _regions(regions), _length(length), _aborted(true) { }
+    ~Cleanup() { if (_aborted) { MemRegion::destroy_array(_regions, _length); } }
+  } cleanup(regions, max);
 
   FileMapRegion* si;
   int region_num = 0;

src/hotspot/share/memory/memRegion.cpp

@@ -102,10 +102,20 @@ MemRegion MemRegion::minus(const MemRegion mr2) const {
   return MemRegion();
 }
 
-MemRegion* MemRegion::create_array(uint length, MEMFLAGS flags) {
+MemRegion* MemRegion::create_array(size_t length, MEMFLAGS flags) {
   MemRegion* result = NEW_C_HEAP_ARRAY(MemRegion, length, flags);
-  for (uint i = 0; i < length; i++) {
+  for (size_t i = 0; i < length; i++) {
     ::new (&result[i]) MemRegion();
   }
   return result;
 }
+
+void MemRegion::destroy_array(MemRegion* array, size_t length) {
+  if (array == NULL) {
+    return;
+  }
+  for (size_t i = 0; i < length; i++) {
+    array[i].~MemRegion();
+  }
+  FREE_C_HEAP_ARRAY(MemRegion, array);
+}

src/hotspot/share/memory/memRegion.hpp

@@ -94,7 +94,8 @@ public:
   bool is_empty() const { return word_size() == 0; }
 
   // Creates and initializes an array of MemRegions of the given length.
-  static MemRegion* create_array(uint length, MEMFLAGS flags);
+  static MemRegion* create_array(size_t length, MEMFLAGS flags);
+  static void destroy_array(MemRegion* array, size_t length);
 };
 
 // For iteration over MemRegion's.