8014405: G1: PerRegionTable::fl_mem_size() calculates size of the free list...

8014405: G1: PerRegionTable::fl_mem_size() calculates size of the free list using wrong element sizes
Summary: Instead of using a simple sizeof(), ask the PerRegionTable class about its size when iterating over the free list.
Reviewed-by: jwilhelm, brutisso

src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp

@@ -242,11 +242,13 @@ public:
     PerRegionTable* cur = _free_list;
     size_t res = 0;
     while (cur != NULL) {
-      res += sizeof(PerRegionTable);
+      res += cur->mem_size();
       cur = cur->next();
     }
     return res;
   }
+
+  static void test_fl_mem_size();
 };
 
 PerRegionTable* PerRegionTable::_free_list = NULL;
@@ -1149,6 +1151,19 @@ HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
 }
 
 #ifndef PRODUCT
+void PerRegionTable::test_fl_mem_size() {
+  PerRegionTable* dummy = alloc(NULL);
+  free(dummy);
+  guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size");
+  // try to reset the state
+  _free_list = NULL;
+  delete dummy;
+}
+
+void HeapRegionRemSet::test_prt() {
+  PerRegionTable::test_fl_mem_size();
+}
+
 void HeapRegionRemSet::test() {
   os::sleep(Thread::current(), (jlong)5000, false);
   G1CollectedHeap* g1h = G1CollectedHeap::heap();

src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp

@@ -338,6 +338,7 @@ public:
 
   // Run unit tests.
 #ifndef PRODUCT
+  static void test_prt();
   static void test();
 #endif
 };

src/share/vm/prims/jni.cpp

@@ -5015,6 +5015,9 @@ _JNI_IMPORT_OR_EXPORT_ jint JNICALL JNI_GetDefaultJavaVMInitArgs(void *args_) {
 #ifndef PRODUCT
 
 #include "gc_interface/collectedHeap.hpp"
+#if INCLUDE_ALL_GCS
+#include "gc_implementation/g1/heapRegionRemSet.hpp"
+#endif
 #include "utilities/quickSort.hpp"
 #if INCLUDE_VM_STRUCTS
 #include "runtime/vmStructs.hpp"
@@ -5034,6 +5037,9 @@ void execute_internal_vm_tests() {
     run_unit_test(AltHashing::test_alt_hash());
 #if INCLUDE_VM_STRUCTS
     run_unit_test(VMStructs::test());
+#endif
+#if INCLUDE_ALL_GCS
+    run_unit_test(HeapRegionRemSet::test_prt());
 #endif
     tty->print_cr("All internal VM tests passed");
   }