8348239: SA does not know about DeoptimizeObjectsALotThread

Reviewed-by: kevinw, dlong, dholmes, lmesnik

src/hotspot/share/compiler/compileBroker.cpp

@@ -773,20 +773,6 @@ void CompileBroker::compilation_init(JavaThread* THREAD) {
 }
 
 #if defined(ASSERT) && COMPILER2_OR_JVMCI
-// Stress testing. Dedicated threads revert optimizations based on escape analysis concurrently to
-// the running java application.  Configured with vm options DeoptimizeObjectsALot*.
-class DeoptimizeObjectsALotThread : public JavaThread {
-
-  static void deopt_objs_alot_thread_entry(JavaThread* thread, TRAPS);
-  void deoptimize_objects_alot_loop_single();
-  void deoptimize_objects_alot_loop_all();
-
-public:
-  DeoptimizeObjectsALotThread() : JavaThread(&deopt_objs_alot_thread_entry) { }
-
-  bool is_hidden_from_external_view() const      { return true; }
-};
-
 // Entry for DeoptimizeObjectsALotThread. The threads are started in
 // CompileBroker::init_compiler_threads() iff DeoptimizeObjectsALot is enabled
 void DeoptimizeObjectsALotThread::deopt_objs_alot_thread_entry(JavaThread* thread, TRAPS) {

src/hotspot/share/compiler/compileBroker.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -39,6 +39,22 @@
 
 class nmethod;
 
+#if defined(ASSERT) && COMPILER2_OR_JVMCI
+// Stress testing. Dedicated threads revert optimizations based on escape analysis concurrently to
+// the running java application.  Configured with vm options DeoptimizeObjectsALot*.
+class DeoptimizeObjectsALotThread : public JavaThread {
+
+  static void deopt_objs_alot_thread_entry(JavaThread* thread, TRAPS);
+  void deoptimize_objects_alot_loop_single();
+  void deoptimize_objects_alot_loop_all();
+
+public:
+  DeoptimizeObjectsALotThread() : JavaThread(&deopt_objs_alot_thread_entry) { }
+
+  bool is_hidden_from_external_view() const      { return true; }
+};
+#endif
+
 // CompilerCounters
 //
 // Per Compiler Performance Counters.

src/hotspot/share/runtime/vmStructs.cpp

@@ -1261,6 +1261,8 @@
         declare_type(CompilerThread, JavaThread)                          \
         declare_type(StringDedupThread, JavaThread)                       \
         declare_type(AttachListenerThread, JavaThread)                    \
+        DEBUG_ONLY(COMPILER2_OR_JVMCI_PRESENT(                            \
+          declare_type(DeoptimizeObjectsALotThread, JavaThread)))         \
   declare_toplevel_type(OSThread)                                         \
   declare_toplevel_type(JavaFrameAnchor)                                  \
                                                                           \

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/DeoptimizeObjectsALotThread.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+package sun.jvm.hotspot.runtime;
+
+import java.io.*;
+
+import sun.jvm.hotspot.debugger.Address;
+
+public class DeoptimizeObjectsALotThread extends JavaThread {
+
+  public DeoptimizeObjectsALotThread (Address addr) {
+    super(addr);
+  }
+
+  public boolean isJavaThread() { return false; }
+  public boolean isHiddenFromExternalView() { return true; }
+
+  public boolean isDeoptimizeObjectsALotThread() { return true; }
+
+}

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/Thread.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -89,6 +89,7 @@ public long allocatedBytes() {
   public boolean   isServiceThread()             { return false; }
   public boolean   isMonitorDeflationThread()    { return false; }
   public boolean   isAttachListenerThread()      { return false; }
+  public boolean   isDeoptimizeObjectsALotThread() { return false; }
 
   /** Memory operations */
   public void oopsDo(AddressVisitor oopVisitor) {

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/Threads.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -155,19 +155,19 @@ private static synchronized void initialize(TypeDataBase db) {
         virtualConstructor.addMapping("NotificationThread", NotificationThread.class);
         virtualConstructor.addMapping("StringDedupThread", StringDedupThread.class);
         virtualConstructor.addMapping("AttachListenerThread", AttachListenerThread.class);
+        virtualConstructor.addMapping("DeoptimizeObjectsALotThread", DeoptimizeObjectsALotThread.class);
     }
 
     public Threads() {
         _list = VMObjectFactory.newObject(ThreadsList.class, threadListField.getValue());
     }
 
-    /** NOTE: this returns objects of type JavaThread, CompilerThread,
-      JvmtiAgentThread, NotificationThread, MonitorDeflationThread,
-      StringDedupThread, AttachListenerThread and ServiceThread.
-      The latter seven subclasses of the former. Most operations
-      (fetching the top frame, etc.) are only allowed to be performed on
-      a "pure" JavaThread. For this reason, {@link
-      sun.jvm.hotspot.runtime.JavaThread#isJavaThread} has been
+    /** NOTE: this returns objects of type JavaThread or one if its subclasses:
+      CompilerThread, JvmtiAgentThread, NotificationThread, MonitorDeflationThread,
+      StringDedupThread, AttachListenerThread, DeoptimizeObjectsALotThread and
+      ServiceThread. Most operations (fetching the top frame, etc.) are only
+      allowed to be performed on a "pure" JavaThread. For this reason,
+      {@link sun.jvm.hotspot.runtime.JavaThread#isJavaThread} has been
       changed from the definition in the VM (which returns true for
       all of these thread types) to return true for JavaThreads and
       false for the seven subclasses. FIXME: should reconsider the
@@ -195,7 +195,7 @@ public JavaThread createJavaThreadWrapper(Address threadAddr) {
         } catch (Exception e) {
             throw new RuntimeException("Unable to deduce type of thread from address " + threadAddr +
             " (expected type JavaThread, CompilerThread, MonitorDeflationThread, AttachListenerThread," +
-            " StringDedupThread, NotificationThread, ServiceThread or JvmtiAgentThread)", e);
+            " DeoptimizeObjectsALotThread, StringDedupThread, NotificationThread, ServiceThread or JvmtiAgentThread)", e);
         }
     }