src/share/vm/memory/universe.cpp

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rev 4773 : 8005849: JEP 167: Event-Based JVM Tracing
Reviewed-by: acorn, coleenp, sla
Contributed-by: Karen Kinnear <karen.kinnear@oracle.com>, Bengt Rutisson <bengt.rutisson@oracle.com>, Calvin Cheung <calvin.cheung@oracle.com>, Erik Gahlin <erik.gahlin@oracle.com>, Erik Helin <erik.helin@oracle.com>, Jesper Wilhelmsson <jesper.wilhelmsson@oracle.com>, Keith McGuigan <keith.mcguigan@oracle.com>, Mattias Tobiasson <mattias.tobiasson@oracle.com>, Markus Gronlund <markus.gronlund@oracle.com>, Mikael Auno <mikael.auno@oracle.com>, Nils Eliasson <nils.eliasson@oracle.com>, Nils Loodin <nils.loodin@oracle.com>, Rickard Backman <rickard.backman@oracle.com>, Staffan Larsen <staffan.larsen@oracle.com>, Stefan Karlsson <stefan.karlsson@oracle.com>, Yekaterina Kantserova <yekaterina.kantserova@oracle.com>

@@ -817,16 +817,18 @@
         ((uint64_t)Universe::heap()->base() + Universe::class_metaspace_size() > KlassEncodingMetaspaceMax))) {
       // Can't reserve heap below 32Gb.
       // keep the Universe::narrow_oop_base() set in Universe::reserve_heap()
       Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
       if (verbose) {
-        tty->print(", Compressed Oops with base: "PTR_FORMAT, Universe::narrow_oop_base());
+        tty->print(", %s: "PTR_FORMAT,
+            narrow_oop_mode_to_string(HeapBasedNarrowOop),
+            Universe::narrow_oop_base());
       }
     } else {
       Universe::set_narrow_oop_base(0);
       if (verbose) {
-        tty->print(", zero based Compressed Oops");
+        tty->print(", %s", narrow_oop_mode_to_string(ZeroBasedNarrowOop));
       }
 #ifdef _WIN64
       if (!Universe::narrow_oop_use_implicit_null_checks()) {
         // Don't need guard page for implicit checks in indexed addressing
         // mode with zero based Compressed Oops.

@@ -837,11 +839,11 @@
         // Can't reserve heap below 4Gb.
         Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
       } else {
         Universe::set_narrow_oop_shift(0);
         if (verbose) {
-          tty->print(", 32-bits Oops");
+          tty->print(", %s", narrow_oop_mode_to_string(UnscaledNarrowOop));
         }
       }
     }
     if (verbose) {
       tty->cr();

@@ -944,10 +946,37 @@
   _heap_capacity_at_last_gc = heap()->capacity();
   _heap_used_at_last_gc     = heap()->used();
 }
 
 
+const char* Universe::narrow_oop_mode_to_string(Universe::NARROW_OOP_MODE mode) {
+  switch (mode) {
+    case UnscaledNarrowOop:
+      return "32-bits Oops";
+    case ZeroBasedNarrowOop:
+      return "zero based Compressed Oops";
+    case HeapBasedNarrowOop:
+      return "Compressed Oops with base";
+  }
+
+  ShouldNotReachHere();
+  return "";
+}
+
+
+Universe::NARROW_OOP_MODE Universe::narrow_oop_mode() {
+  if (narrow_oop_base() != 0) {
+    return HeapBasedNarrowOop;
+  }
+
+  if (narrow_oop_shift() != 0) {
+    return ZeroBasedNarrowOop;
+  }
+
+  return UnscaledNarrowOop;
+}
+
 
 void universe2_init() {
   EXCEPTION_MARK;
   Universe::genesis(CATCH);
 }