8292910: Remove root to oop cast in HeapDumper

Reviewed-by: eosterlund, coleenp

Author: stefank

src/hotspot/share/services/heapDumper.cpp

@@ -410,6 +410,9 @@ class AbstractDumpWriter : public StackObj {
 
   // Returns true if we have enough room in the buffer for 'len' bytes.
   bool can_write_fast(size_t len);
+
+  void write_address(address a);
+
  public:
   AbstractDumpWriter() :
     _buffer(NULL),
@@ -429,6 +432,7 @@ class AbstractDumpWriter : public StackObj {
   void write_u4(u4 x);
   void write_u8(u8 x);
   void write_objectID(oop o);
+  void write_rootID(oop* p);
   void write_symbolID(Symbol* o);
   void write_classID(Klass* k);
   void write_id(u4 x);
@@ -511,22 +515,24 @@ void AbstractDumpWriter::write_u8(u8 x) {
   WRITE_KNOWN_TYPE(&v, 8);
 }
 
-void AbstractDumpWriter::write_objectID(oop o) {
-  address a = cast_from_oop<address>(o);
+void AbstractDumpWriter::write_address(address a) {
 #ifdef _LP64
   write_u8((u8)a);
 #else
   write_u4((u4)a);
 #endif
 }
 
+void AbstractDumpWriter::write_objectID(oop o) {
+  write_address(cast_from_oop<address>(o));
+}
+
+void AbstractDumpWriter::write_rootID(oop* p) {
+  write_address((address)p);
+}
+
 void AbstractDumpWriter::write_symbolID(Symbol* s) {
-  address a = (address)((uintptr_t)s);
-#ifdef _LP64
-  write_u8((u8)a);
-#else
-  write_u4((u4)a);
-#endif
+  write_address((address)((uintptr_t)s));
 }
 
 void AbstractDumpWriter::write_id(u4 x) {
@@ -1581,7 +1587,7 @@ void JNIGlobalsDumper::do_oop(oop* obj_p) {
     u4 size = 1 + 2 * sizeof(address);
     writer()->start_sub_record(HPROF_GC_ROOT_JNI_GLOBAL, size);
     writer()->write_objectID(o);
-    writer()->write_objectID((oopDesc*)obj_p);      // global ref ID
+    writer()->write_rootID(obj_p);      // global ref ID
     writer()->end_sub_record();
   }
 };