8382332: Large regression (~50%) in SPECjbb2015 when using JFR after JEP 500

src/hotspot/share/ci/ciInstanceKlass.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2026, 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
@@ -432,6 +432,55 @@ ciField* ciInstanceKlass::get_field_by_name(ciSymbol* name, ciSymbol* signature,
   return field;
 }
 
+#ifdef ASSERT
+static void assert_injected_field(InternalFieldStream& fs) {
+  assert(!fs.done(), "invarinat");
+  fieldDescriptor fd = fs.field_descriptor();
+  assert(fd.is_injected(), "invariant");
+}
+#endif
+
+// ------------------------------------------------------------------
+// ciInstanceKlass::get_injected_instance_field_by_name
+//
+// Implements also compute_injected_fields().
+//
+ciField* ciInstanceKlass::get_injected_instance_field_by_name(ciSymbol* name, ciSymbol* signature) {
+  VM_ENTRY_MARK;
+  InstanceKlass* const k = get_instanceKlass();
+  const Symbol* const name_symbol = name->get_symbol();
+  assert(name_symbol != nullptr, "invariant");
+  const Symbol* const sig_sym = signature->get_symbol();
+  assert(sig_sym != nullptr, "invariant");
+
+  if (_has_injected_fields == -1) {
+    if (super() != nullptr && super()->has_injected_fields()) {
+      _has_injected_fields = 1;
+    }
+  }
+
+  ciField* injected = nullptr;
+  for (InternalFieldStream fs(k); !fs.done(); fs.next()) {
+    if (fs.access_flags().is_static())  continue;
+    DEBUG_ONLY(assert_injected_field(fs);)
+    if (_has_injected_fields == -1) {
+      _has_injected_fields = 1;
+    }
+    if (fs.name() == name_symbol && fs.signature() == sig_sym) {
+      fieldDescriptor fd = fs.field_descriptor();
+      assert(fd.is_injected(), "invariant");
+      injected = new (CURRENT_THREAD_ENV->arena()) ciField(&fd);
+      break;
+    }
+  }
+
+  if (_has_injected_fields == -1) {
+    _has_injected_fields = 0;
+  }
+
+  return injected;
+}
+
 // This is essentially a shortcut for:
 //   get_field_by_offset(field_offset, is_static)->layout_type()
 // except this does not require allocating memory for a new ciField

src/hotspot/share/ci/ciInstanceKlass.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2026, 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
@@ -215,6 +215,7 @@ class ciInstanceKlass : public ciKlass {
   ciInstanceKlass* get_canonical_holder(int offset);
   ciField* get_field_by_offset(int field_offset, bool is_static);
   ciField* get_field_by_name(ciSymbol* name, ciSymbol* signature, bool is_static);
+  ciField* get_injected_instance_field_by_name(ciSymbol* name, ciSymbol* signature);
   BasicType get_field_type_by_offset(int field_offset, bool is_static);
 
   // total number of nonstatic fields (including inherited):

src/hotspot/share/classfile/javaClasses.cpp

@@ -3588,6 +3588,7 @@ int java_lang_reflect_Field::_modifiers_offset;
 int java_lang_reflect_Field::_trusted_final_offset;
 int java_lang_reflect_Field::_signature_offset;
 int java_lang_reflect_Field::_annotations_offset;
+JFR_ONLY(int java_lang_reflect_Field::_jfr_epoch_offset;)
 
 #define FIELD_FIELDS_DO(macro) \
   macro(_clazz_offset,     k, vmSymbols::clazz_name(),     class_signature,  false); \
@@ -3602,11 +3603,13 @@ int java_lang_reflect_Field::_annotations_offset;
 void java_lang_reflect_Field::compute_offsets() {
   InstanceKlass* k = vmClasses::reflect_Field_klass();
   FIELD_FIELDS_DO(FIELD_COMPUTE_OFFSET);
+  JFR_ONLY(FIELD_INJECTED_FIELDS(INJECTED_FIELD_COMPUTE_OFFSET);)
 }
 
 #if INCLUDE_CDS
 void java_lang_reflect_Field::serialize_offsets(SerializeClosure* f) {
   FIELD_FIELDS_DO(FIELD_SERIALIZE_OFFSET);
+  JFR_ONLY(FIELD_INJECTED_FIELDS(INJECTED_FIELD_SERIALIZE_OFFSET);)
 }
 #endif
 
@@ -3672,6 +3675,29 @@ void java_lang_reflect_Field::set_annotations(oop field, oop value) {
   field->obj_field_put(_annotations_offset, value);
 }
 
+#if INCLUDE_JFR
+u2 java_lang_reflect_Field::epoch(oop ref) {
+  return static_cast<u2>(ref->int_field(_jfr_epoch_offset));
+}
+
+int jdk_internal_event_JfrEpoch::_jfr_epoch_offset;
+
+void jdk_internal_event_JfrEpoch::compute_offsets() {
+  InstanceKlass* k = vmClasses::jfrEpoch_klass();
+  JFR_EPOCH_INJECTED_FIELDS(INJECTED_FIELD_COMPUTE_OFFSET);
+}
+
+#if INCLUDE_CDS
+void jdk_internal_event_JfrEpoch::serialize_offsets(SerializeClosure* f) {
+  JFR_EPOCH_INJECTED_FIELDS(INJECTED_FIELD_SERIALIZE_OFFSET);
+}
+#endif
+
+u2 jdk_internal_event_JfrEpoch::epoch(oop ref) {
+  return static_cast<u2>(ref->int_field(_jfr_epoch_offset));
+}
+#endif // INCLUDE_JFR
+
 oop java_lang_reflect_RecordComponent::create(InstanceKlass* holder, RecordComponent* component, TRAPS) {
   // Allocate java.lang.reflect.RecordComponent instance
   HandleMark hm(THREAD);
@@ -5397,6 +5423,7 @@ void java_lang_InternalError::serialize_offsets(SerializeClosure* f) {
   f(jdk_internal_misc_UnsafeConstants) \
   f(java_lang_boxing_object) \
   f(vector_VectorPayload) \
+  JFR_ONLY(f(jdk_internal_event_JfrEpoch)) \
   //end
 
 #define BASIC_JAVA_CLASSES_DO(f) \

src/hotspot/share/classfile/javaClasses.hpp

@@ -820,6 +820,32 @@ class java_lang_reflect_Constructor : public java_lang_reflect_AccessibleObject
 };
 
 
+#if INCLUDE_JFR
+
+#define JFR_EPOCH_INJECTED_FIELDS(macro) \
+  macro(jdk_internal_event_JfrEpoch, jfr_epoch, int_signature, false)
+
+class jdk_internal_event_JfrEpoch : AllStatic {
+ private:
+  static int _jfr_epoch_offset;
+
+  static void compute_offsets();
+
+ public:
+  static void serialize_offsets(SerializeClosure* f) NOT_CDS_RETURN;
+
+  static u2 epoch(oop field);
+  static int epoch_offset() { CHECK_INIT(_jfr_epoch_offset); }
+
+  // Debugging
+  friend class JavaClasses;
+};
+
+#define FIELD_INJECTED_FIELDS(macro) \
+  macro(java_lang_reflect_Field, jfr_epoch, int_signature, false)
+
+#endif // INCLUDE_JFR
+
 // Interface to java.lang.reflect.Field objects
 
 class java_lang_reflect_Field : public java_lang_reflect_AccessibleObject {
@@ -834,6 +860,7 @@ class java_lang_reflect_Field : public java_lang_reflect_AccessibleObject {
   static int _trusted_final_offset;
   static int _signature_offset;
   static int _annotations_offset;
+  JFR_ONLY(static int _jfr_epoch_offset;)
 
   static void compute_offsets();
 
@@ -864,6 +891,9 @@ class java_lang_reflect_Field : public java_lang_reflect_AccessibleObject {
   static void set_signature(oop constructor, oop value);
   static void set_annotations(oop constructor, oop value);
 
+  JFR_ONLY(static u2 epoch(oop field);)
+  JFR_ONLY(static int epoch_offset() { CHECK_INIT(_jfr_epoch_offset); })
+
   // Debugging
   friend class JavaClasses;
 };

src/hotspot/share/classfile/javaClassesImpl.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2026, 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
@@ -43,7 +43,9 @@
   VTHREAD_INJECTED_FIELDS(macro)            \
   INTERNALERROR_INJECTED_FIELDS(macro)      \
   STACKCHUNK_INJECTED_FIELDS(macro)         \
-  CONSTANTPOOL_INJECTED_FIELDS(macro)
+  CONSTANTPOOL_INJECTED_FIELDS(macro)       \
+  JFR_ONLY(FIELD_INJECTED_FIELDS(macro))    \
+  JFR_ONLY(JFR_EPOCH_INJECTED_FIELDS(macro))
 
 #define INJECTED_FIELD_COMPUTE_OFFSET(klass, name, signature, may_be_java) \
   klass::_##name##_offset = JavaClasses::compute_injected_offset(InjectedFieldID::klass##_##name##_enum);

src/hotspot/share/classfile/vmClassMacros.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2026, 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
@@ -193,6 +193,9 @@
   /* Scoped Values */                                                                                           \
   do_klass(ScopedValue_Carrier_klass,                   java_lang_ScopedValue_Carrier                         ) \
                                                                                                                 \
+  /* Jfr */                                                                                                     \
+  JFR_ONLY(do_klass(jfrEpoch_klass,                     jdk_internal_event_JfrEpoch                          )) \
+                                                                                                                \
   /*end*/
 
 #endif // SHARE_CLASSFILE_VMCLASSMACROS_HPP

src/hotspot/share/include/jvm.h

@@ -329,6 +329,9 @@ JVM_FindScopedValueBindings(JNIEnv *env, jclass threadClass);
 JNIEXPORT jlong JNICALL
 JVM_GetNextThreadIdOffset(JNIEnv *env, jclass threadClass);
 
+JNIEXPORT jboolean JNICALL
+JVM_JfrEpochUpdate(JNIEnv* env, jclass jfrEpoch, jobject obj);
+
 /*
  * jdk.internal.vm.Continuation
  */

src/hotspot/share/jfr/jfr.cpp

@@ -28,6 +28,7 @@
 #include "jfr/jni/jfrJavaSupport.hpp"
 #include "jfr/leakprofiler/leakProfiler.hpp"
 #include "jfr/recorder/checkpoint/jfrCheckpointManager.hpp"
+#include "jfr/recorder/checkpoint/types/traceid/jfrTraceIdEpoch.hpp"
 #include "jfr/recorder/jfrRecorder.hpp"
 #include "jfr/recorder/repository/jfrEmergencyDump.hpp"
 #include "jfr/recorder/repository/jfrRepository.hpp"
@@ -44,7 +45,6 @@
 #include "runtime/java.hpp"
 #include "runtime/javaThread.hpp"
 
-
 bool Jfr::is_enabled() {
   return JfrRecorder::is_enabled();
 }
@@ -181,6 +181,10 @@ void Jfr::on_report_java_out_of_memory() {
   }
 }
 
+bool Jfr::update_epoch(oop oop) {
+  return JfrTraceIdEpoch::update(oop);
+}
+
 #if INCLUDE_CDS
 void Jfr::on_restoration(const Klass* k, JavaThread* jt) {
   assert(k != nullptr, "invariant");

src/hotspot/share/jfr/jfr.hpp

@@ -80,6 +80,7 @@ class Jfr : AllStatic {
   static bool has_sample_request(JavaThread* jt);
   static void check_and_process_sample_request(JavaThread* jt);
   static void on_report_java_out_of_memory();
+  static bool update_epoch(oop obj);
   CDS_ONLY(static void on_restoration(const Klass* k, JavaThread* jt);)
 };
 

src/hotspot/share/jfr/recorder/checkpoint/types/traceid/jfrOopTraceId.hpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2020, 2026, 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
@@ -28,6 +28,7 @@
 #include "jfr/utilities/jfrTypes.hpp"
 #include "memory/allocation.hpp"
 #include "oops/oopsHierarchy.hpp"
+#include "runtime/atomicAccess.hpp"
 
 template <typename T>
 class JfrOopTraceId : AllStatic {
@@ -37,6 +38,7 @@ class JfrOopTraceId : AllStatic {
   static u2 current_epoch();
   static void set_epoch(oop ref);
   static void set_epoch(oop ref, u2 epoch);
+  static bool cas_epoch(oop ref);
   static bool is_excluded(oop ref);
   static void exclude(oop ref);
   static void include(oop ref);

src/hotspot/share/jfr/recorder/checkpoint/types/traceid/jfrOopTraceId.inline.hpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2020, 2026, 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
@@ -57,6 +57,17 @@ inline void JfrOopTraceId<T>::set_epoch(oop ref) {
   set_epoch(ref, JfrTraceIdEpoch::epoch_generation());
 }
 
+template <typename T>
+inline bool JfrOopTraceId<T>::cas_epoch(oop ref) {
+  const int expected = epoch(ref);
+  const int current = current_epoch();
+  if (expected == current) {
+    return false;
+  }
+  int* const epoch_address = ref->field_addr<int>(T::epoch_offset());
+  return AtomicAccess::cmpxchg(epoch_address, expected, current) == expected;
+}
+
 template <typename T>
 inline bool JfrOopTraceId<T>::is_excluded(oop ref) {
   return T::is_excluded(ref);

src/hotspot/share/jfr/recorder/checkpoint/types/traceid/jfrTraceIdEpoch.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2026, 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
@@ -22,6 +22,9 @@
  *
  */
 
+#include "classfile/javaClasses.inline.hpp"
+#include "classfile/vmSymbols.hpp"
+#include "jfr/recorder/checkpoint/types/traceid/jfrOopTraceId.inline.hpp"
 #include "jfr/recorder/checkpoint/types/traceid/jfrTraceIdEpoch.hpp"
 #include "jfr/support/jfrThreadId.inline.hpp"
 #include "runtime/atomicAccess.hpp"
@@ -65,3 +68,28 @@ void JfrTraceIdEpoch::reset_method_tracer_tag_state() {
 bool JfrTraceIdEpoch::has_method_tracer_changed_tag_state() {
   return AtomicAccess::load_acquire(&_method_tracer_state);
 }
+
+#ifdef ASSERT
+static void assert_epoch_supported_type(oop obj) {
+  assert(obj != nullptr, "invariant");
+  assert(obj->is_instance(), "invariant");
+  const InstanceKlass* const ik = InstanceKlass::cast(obj->klass());
+  assert(ik != nullptr, "invariant");
+  vmSymbolID sid = vmSymbols::find_sid(ik->name());
+  assert(sid == vmSymbolID::java_lang_reflect_Field_enum ||
+    sid == vmSymbolID::jdk_internal_event_JfrEpoch_enum, "invariant");
+}
+#endif
+
+// Switch on the vmSymbolID for dispatch.
+bool JfrTraceIdEpoch::update(oop obj) {
+  DEBUG_ONLY(assert_epoch_supported_type(obj);)
+  const InstanceKlass* const ik = InstanceKlass::cast(obj->klass());
+  assert(ik != nullptr, "invariant");
+  const vmSymbolID sid = vmSymbols::find_sid(ik->name());
+  if (sid == vmSymbolID::java_lang_reflect_Field_enum) {
+    return JfrOopTraceId<java_lang_reflect_Field>::cas_epoch(obj);
+  }
+  assert(sid == vmSymbolID::jdk_internal_event_JfrEpoch_enum, "invariant");
+  return JfrOopTraceId<jdk_internal_event_JfrEpoch>::cas_epoch(obj);
+}

src/hotspot/share/jfr/recorder/checkpoint/types/traceid/jfrTraceIdEpoch.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2026, 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
@@ -135,6 +135,9 @@ class JfrTraceIdEpoch : AllStatic {
   static void set_method_tracer_tag_state();
   static void reset_method_tracer_tag_state();
   static bool has_method_tracer_changed_tag_state();
+
+  static bool update(oop obj);
+
 };
 
 #endif // SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDEPOCH_HPP