8260630: Templatize literal_size

8260629: Remove explicit instantiation of Hashtable with oop value

Reviewed-by: pliden, tschatzl, coleenp

Author: Kim Barrett

src/hotspot/share/utilities/hashtable.cpp

@@ -110,22 +110,18 @@ template <MEMFLAGS F> void BasicHashtable<F>::free_buckets() {
   _buckets = NULL;
 }
 
-// For oops and Strings the size of the literal is interesting. For other types, nobody cares.
-static int literal_size(ConstantPool*) { return 0; }
-static int literal_size(Klass*)        { return 0; }
-static int literal_size(nmethod*)      { return 0; }
+// Default overload, for types that are uninteresting.
+template<typename T> static int literal_size(T) { return 0; }
 
 static int literal_size(Symbol *symbol) {
   return symbol->size() * HeapWordSize;
 }
 
 static int literal_size(oop obj) {
-  // NOTE: this would over-count if (pre-JDK8) java_lang_Class::has_offset_field() is true,
-  // and the String.value array is shared by several Strings. However, starting from JDK8,
-  // the String.value array is not shared anymore.
   if (obj == NULL) {
     return 0;
   } else if (obj->klass() == SystemDictionary::String_klass()) {
+    // This may overcount if String.value arrays are shared.
     return (obj->size() + java_lang_String::value(obj)->size()) * HeapWordSize;
   } else {
     return obj->size();
@@ -235,10 +231,6 @@ template <class T, MEMFLAGS F> TableStatistics Hashtable<T, F>::statistics_calcu
 }
 
 // Dump footprint and bucket length statistics
-//
-// Note: if you create a new subclass of Hashtable<MyNewType, F>, you will need to
-// add a new function static int literal_size(MyNewType lit)
-// because I can't get template <class T> int literal_size(T) to pick the specializations for Symbol and oop.
 template <class T, MEMFLAGS F> void Hashtable<T, F>::print_table_statistics(outputStream* st,
                                                                             const char *table_name,
                                                                             T (*literal_load_barrier)(HashtableEntry<T, F>*)) {
@@ -318,11 +310,9 @@ template class Hashtable<InstanceKlass*, mtClass>;
 template class Hashtable<WeakHandle, mtClass>;
 template class Hashtable<WeakHandle, mtServiceability>;
 template class Hashtable<Symbol*, mtModule>;
-template class Hashtable<oop, mtSymbol>;
 template class Hashtable<Symbol*, mtClass>;
 template class HashtableEntry<Symbol*, mtSymbol>;
 template class HashtableEntry<Symbol*, mtClass>;
-template class HashtableEntry<oop, mtSymbol>;
 template class HashtableBucket<mtClass>;
 template class BasicHashtableEntry<mtSymbol>;
 template class BasicHashtableEntry<mtCode>;