Merge tag 'jdk-23+31' into ola/24.1_jdk-23+31

Added tag jdk-23+31 for changeset 6720685

Author: marwan-hallaoui

src/hotspot/share/classfile/classLoaderDataGraph.cpp

@@ -241,22 +241,23 @@ LockedClassesDo::~LockedClassesDo() {
 
 
 // Iterating over the CLDG needs to be locked because
-// unloading can remove entries concurrently soon.
-template <bool keep_alive = true>
-class ClassLoaderDataGraphIteratorBase : public StackObj {
+// unloading can remove entries concurrently.
+// This iterator does not keep the CLD alive.
+// Any CLD OopHandles (modules, mirrors, resolved refs)
+// resolved must be treated as no keepalive. And requires
+// that its CLD's holder is kept alive if they escape the
+// caller's safepoint or ClassLoaderDataGraph_lock
+// critical section.
+class ClassLoaderDataGraph::ClassLoaderDataGraphIterator : public StackObj {
   ClassLoaderData* _next;
   Thread*          _thread;
   HandleMark       _hm;  // clean up handles when this is done.
   NoSafepointVerifier _nsv; // No safepoints allowed in this scope
                             // unless verifying at a safepoint.
 
 public:
-  ClassLoaderDataGraphIteratorBase() : _next(ClassLoaderDataGraph::_head), _thread(Thread::current()), _hm(_thread) {
-    if (keep_alive) {
-      assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
-    } else {
-      assert_at_safepoint();
-    }
+  ClassLoaderDataGraphIterator() : _next(ClassLoaderDataGraph::_head), _thread(Thread::current()), _hm(_thread) {
+    assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
   }
 
   ClassLoaderData* get_next() {
@@ -266,10 +267,6 @@ class ClassLoaderDataGraphIteratorBase : public StackObj {
       cld = cld->next();
     }
     if (cld != nullptr) {
-      if (keep_alive) {
-        // Keep cld that is being returned alive.
-        Handle(_thread, cld->holder());
-      }
       _next = cld->next();
     } else {
       _next = nullptr;
@@ -278,23 +275,13 @@ class ClassLoaderDataGraphIteratorBase : public StackObj {
   }
 };
 
-using ClassLoaderDataGraphIterator = ClassLoaderDataGraphIteratorBase<true /* keep_alive */>;
-using ClassLoaderDataGraphIteratorNoKeepAlive = ClassLoaderDataGraphIteratorBase<false /* keep_alive */>;
-
 void ClassLoaderDataGraph::loaded_cld_do(CLDClosure* cl) {
   ClassLoaderDataGraphIterator iter;
   while (ClassLoaderData* cld = iter.get_next()) {
     cl->do_cld(cld);
   }
 }
 
-void ClassLoaderDataGraph::loaded_cld_do_no_keepalive(CLDClosure* cl) {
-  ClassLoaderDataGraphIteratorNoKeepAlive iter;
-  while (ClassLoaderData* cld = iter.get_next()) {
-    cl->do_cld(cld);
-  }
-}
-
 // These functions assume that the caller has locked the ClassLoaderDataGraph_lock
 // if they are not calling the function from a safepoint.
 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
@@ -318,6 +305,16 @@ void ClassLoaderDataGraph::methods_do(void f(Method*)) {
   }
 }
 
+void ClassLoaderDataGraph::modules_do_keepalive(void f(ModuleEntry*)) {
+  assert_locked_or_safepoint(Module_lock);
+  ClassLoaderDataGraphIterator iter;
+  while (ClassLoaderData* cld = iter.get_next()) {
+    // Keep the holder alive.
+    (void)cld->holder();
+    cld->modules_do(f);
+  }
+}
+
 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
   assert_locked_or_safepoint(Module_lock);
   ClassLoaderDataGraphIterator iter;
@@ -334,9 +331,11 @@ void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
   }
 }
 
-void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
+void ClassLoaderDataGraph::loaded_classes_do_keepalive(KlassClosure* klass_closure) {
   ClassLoaderDataGraphIterator iter;
   while (ClassLoaderData* cld = iter.get_next()) {
+    // Keep the holder alive.
+    (void)cld->holder();
     cld->loaded_classes_do(klass_closure);
   }
 }
@@ -346,34 +345,36 @@ void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
 }
 
 void ClassLoaderDataGraph::verify_dictionary() {
-  ClassLoaderDataGraphIteratorNoKeepAlive iter;
+  ClassLoaderDataGraphIterator iter;
   while (ClassLoaderData* cld = iter.get_next()) {
     if (cld->dictionary() != nullptr) {
       cld->dictionary()->verify();
     }
   }
 }
 
-#define FOR_ALL_DICTIONARY(X)   ClassLoaderDataGraphIterator iter; \
-                                while (ClassLoaderData* X = iter.get_next()) \
-                                  if (X->dictionary() != nullptr)
-
 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
-  FOR_ALL_DICTIONARY(cld) {
-    st->print("Dictionary for ");
-    cld->print_value_on(st);
-    st->cr();
-    cld->dictionary()->print_on(st);
-    st->cr();
+  ClassLoaderDataGraphIterator iter;
+  while (ClassLoaderData *cld = iter.get_next()) {
+    if (cld->dictionary() != nullptr) {
+      st->print("Dictionary for ");
+      cld->print_value_on(st);
+      st->cr();
+      cld->dictionary()->print_on(st);
+      st->cr();
+    }
   }
 }
 
 void ClassLoaderDataGraph::print_table_statistics(outputStream* st) {
-  FOR_ALL_DICTIONARY(cld) {
-    ResourceMark rm; // loader_name_and_id
-    stringStream tempst;
-    tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
-    cld->dictionary()->print_table_statistics(st, tempst.freeze());
+  ClassLoaderDataGraphIterator iter;
+  while (ClassLoaderData *cld = iter.get_next()) {
+    if (cld->dictionary() != nullptr) {
+      ResourceMark rm; // loader_name_and_id
+      stringStream tempst;
+      tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
+      cld->dictionary()->print_table_statistics(st, tempst.freeze());
+    }
   }
 }
 
@@ -550,7 +551,7 @@ Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
 }
 
 void ClassLoaderDataGraph::verify() {
-  ClassLoaderDataGraphIteratorNoKeepAlive iter;
+  ClassLoaderDataGraphIterator iter;
   while (ClassLoaderData* cld = iter.get_next()) {
     cld->verify();
   }

src/hotspot/share/classfile/classLoaderDataGraph.hpp

@@ -37,10 +37,10 @@ class ClassLoaderDataGraph : public AllStatic {
   friend class ClassLoaderDataGraphMetaspaceIterator;
   friend class ClassLoaderDataGraphKlassIteratorAtomic;
   friend class ClassLoaderDataGraphKlassIteratorStatic;
-  template <bool keep_alive>
-  friend class ClassLoaderDataGraphIteratorBase;
   friend class VMStructs;
  private:
+  class ClassLoaderDataGraphIterator;
+
   // All CLDs (except unlinked CLDs) can be reached by walking _head->_next->...
   static ClassLoaderData* volatile _head;
 
@@ -71,8 +71,12 @@ class ClassLoaderDataGraph : public AllStatic {
   static void roots_cld_do(CLDClosure* strong, CLDClosure* weak);
   static void always_strong_cld_do(CLDClosure* cl);
   // Iteration through CLDG not by GC.
+  // All the do suffixed functions do not keep the CLD alive. Any CLD OopHandles
+  // (modules, mirrors, resolved refs) resolved must be treated as no keepalive.
+  // And requires that its CLD's holder is kept alive if they escape the
+  // caller's safepoint or ClassLoaderDataGraph_lock critical section.
+  // The do_keepalive suffixed functions will keep all CLDs alive.
   static void loaded_cld_do(CLDClosure* cl);
-  static void loaded_cld_do_no_keepalive(CLDClosure* cl);
   // klass do
   // Walking classes through the ClassLoaderDataGraph include array classes.  It also includes
   // classes that are allocated but not loaded, classes that have errors, and scratch classes
@@ -81,9 +85,10 @@ class ClassLoaderDataGraph : public AllStatic {
   static void classes_do(KlassClosure* klass_closure);
   static void classes_do(void f(Klass* const));
   static void methods_do(void f(Method*));
+  static void modules_do_keepalive(void f(ModuleEntry*));
   static void modules_do(void f(ModuleEntry*));
   static void packages_do(void f(PackageEntry*));
-  static void loaded_classes_do(KlassClosure* klass_closure);
+  static void loaded_classes_do_keepalive(KlassClosure* klass_closure);
   static void classes_unloading_do(void f(Klass* const));
   static bool do_unloading();
 

src/hotspot/share/classfile/classLoaderStats.cpp

@@ -165,7 +165,7 @@ void ClassLoaderStatsClosure::addEmptyParents(oop cl) {
 
 void ClassLoaderStatsVMOperation::doit() {
   ClassLoaderStatsClosure clsc (_out);
-  ClassLoaderDataGraph::loaded_cld_do_no_keepalive(&clsc);
+  ClassLoaderDataGraph::loaded_cld_do(&clsc);
   clsc.print();
 }
 

src/hotspot/share/classfile/javaClasses.cpp

@@ -788,6 +788,7 @@ int java_lang_Class::_class_loader_offset;
 int java_lang_Class::_module_offset;
 int java_lang_Class::_protection_domain_offset;
 int java_lang_Class::_component_mirror_offset;
+int java_lang_Class::_init_lock_offset;
 int java_lang_Class::_signers_offset;
 int java_lang_Class::_name_offset;
 int java_lang_Class::_source_file_offset;
@@ -911,6 +912,12 @@ void java_lang_Class::initialize_mirror_fields(Klass* k,
                                                Handle protection_domain,
                                                Handle classData,
                                                TRAPS) {
+  // Allocate a simple java object for a lock.
+  // This needs to be a java object because during class initialization
+  // it can be held across a java call.
+  typeArrayOop r = oopFactory::new_typeArray(T_INT, 0, CHECK);
+  set_init_lock(mirror(), r);
+
   // Set protection domain also
   set_protection_domain(mirror(), protection_domain());
 
@@ -1132,6 +1139,10 @@ bool java_lang_Class::restore_archived_mirror(Klass *k,
   if (!k->is_array_klass()) {
     // - local static final fields with initial values were initialized at dump time
 
+    // create the init_lock
+    typeArrayOop r = oopFactory::new_typeArray(T_INT, 0, CHECK_(false));
+    set_init_lock(mirror(), r);
+
     if (protection_domain.not_null()) {
       set_protection_domain(mirror(), protection_domain());
     }
@@ -1196,6 +1207,15 @@ oop java_lang_Class::component_mirror(oop java_class) {
   return java_class->obj_field(_component_mirror_offset);
 }
 
+oop java_lang_Class::init_lock(oop java_class) {
+  assert(_init_lock_offset != 0, "must be set");
+  return java_class->obj_field(_init_lock_offset);
+}
+void java_lang_Class::set_init_lock(oop java_class, oop init_lock) {
+  assert(_init_lock_offset != 0, "must be set");
+  java_class->obj_field_put(_init_lock_offset, init_lock);
+}
+
 objArrayOop java_lang_Class::signers(oop java_class) {
   assert(_signers_offset != 0, "must be set");
   return (objArrayOop)java_class->obj_field(_signers_offset);
@@ -1415,12 +1435,18 @@ void java_lang_Class::compute_offsets() {
   InstanceKlass* k = vmClasses::Class_klass();
   CLASS_FIELDS_DO(FIELD_COMPUTE_OFFSET);
 
+  // Init lock is a C union with component_mirror.  Only instanceKlass mirrors have
+  // init_lock and only ArrayKlass mirrors have component_mirror.  Since both are oops
+  // GC treats them the same.
+  _init_lock_offset = _component_mirror_offset;
+
   CLASS_INJECTED_FIELDS(INJECTED_FIELD_COMPUTE_OFFSET);
 }
 
 #if INCLUDE_CDS
 void java_lang_Class::serialize_offsets(SerializeClosure* f) {
   f->do_bool(&_offsets_computed);
+  f->do_u4((u4*)&_init_lock_offset);
 
   CLASS_FIELDS_DO(FIELD_SERIALIZE_OFFSET);
 

src/hotspot/share/classfile/javaClasses.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, 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
@@ -226,6 +226,7 @@ class java_lang_Class : AllStatic {
   static int _static_oop_field_count_offset;
 
   static int _protection_domain_offset;
+  static int _init_lock_offset;
   static int _signers_offset;
   static int _class_loader_offset;
   static int _module_offset;
@@ -240,6 +241,7 @@ class java_lang_Class : AllStatic {
   static GrowableArray<Klass*>* _fixup_mirror_list;
   static GrowableArray<Klass*>* _fixup_module_field_list;
 
+  static void set_init_lock(oop java_class, oop init_lock);
   static void set_protection_domain(oop java_class, oop protection_domain);
   static void set_class_loader(oop java_class, oop class_loader);
   static void set_component_mirror(oop java_class, oop comp_mirror);
@@ -292,6 +294,10 @@ class java_lang_Class : AllStatic {
 
   // Support for embedded per-class oops
   static oop  protection_domain(oop java_class);
+  static oop  init_lock(oop java_class);
+  static void clear_init_lock(oop java_class) {
+    set_init_lock(java_class, nullptr);
+  }
   static oop  component_mirror(oop java_class);
   static objArrayOop  signers(oop java_class);
   static void set_signers(oop java_class, objArrayOop signers);

src/hotspot/share/classfile/systemDictionary.hpp

@@ -177,7 +177,7 @@ class SystemDictionary : AllStatic {
 
   static void classes_do(MetaspaceClosure* it);
   // Iterate over all methods in all klasses
-
+  // Will not keep metadata alive. See ClassLoaderDataGraph::methods_do.
   static void methods_do(void f(Method*));
 
   // Garbage collection support

src/hotspot/share/classfile/vmSymbols.hpp

@@ -557,6 +557,7 @@ class SerializeClosure;
   template(bool_array_signature,                      "[Z")                                       \
   template(byte_array_signature,                      "[B")                                       \
   template(char_array_signature,                      "[C")                                       \
+  template(int_array_signature,                       "[I")                                       \
   template(runnable_signature,                        "Ljava/lang/Runnable;")                     \
   template(continuation_signature,                    "Ljdk/internal/vm/Continuation;")           \
   template(continuationscope_signature,               "Ljdk/internal/vm/ContinuationScope;")      \

src/hotspot/share/gc/shared/barrierSetNMethod.cpp

@@ -172,13 +172,9 @@ int BarrierSetNMethod::nmethod_stub_entry_barrier(address* return_address_ptr) {
   nmethod* nm = cb->as_nmethod();
   BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();
 
-  if (!bs_nm->is_armed(nm)) {
-    return 0;
-  }
-
-  assert(!nm->is_osr_method(), "Should not reach here");
   // Called upon first entry after being armed
   bool may_enter = bs_nm->nmethod_entry_barrier(nm);
+  assert(!nm->is_osr_method() || may_enter, "OSR nmethods should always be entrant after migration");
 
   // In case a concurrent thread disarmed the nmethod, we need to ensure the new instructions
   // are made visible, by using a cross modify fence. Note that this is synchronous cross modifying
@@ -188,11 +184,11 @@ int BarrierSetNMethod::nmethod_stub_entry_barrier(address* return_address_ptr) {
   // it can be made conditional on the nmethod_patching_type.
   OrderAccess::cross_modify_fence();
 
-  // Diagnostic option to force deoptimization 1 in 3 times. It is otherwise
+  // Diagnostic option to force deoptimization 1 in 10 times. It is otherwise
   // a very rare event.
-  if (DeoptimizeNMethodBarriersALot) {
+  if (DeoptimizeNMethodBarriersALot && !nm->is_osr_method()) {
     static volatile uint32_t counter=0;
-    if (Atomic::add(&counter, 1u) % 3 == 0) {
+    if (Atomic::add(&counter, 1u) % 10 == 0) {
       may_enter = false;
     }
   }
@@ -205,15 +201,6 @@ int BarrierSetNMethod::nmethod_stub_entry_barrier(address* return_address_ptr) {
 }
 
 bool BarrierSetNMethod::nmethod_osr_entry_barrier(nmethod* nm) {
-  // This check depends on the invariant that all nmethods that are deoptimized / made not entrant
-  // are NOT disarmed.
-  // This invariant is important because a method can be deoptimized after the method have been
-  // resolved / looked up by OSR by another thread. By not deoptimizing them we guarantee that
-  // a deoptimized method will always hit the barrier and come to the same conclusion - deoptimize
-  if (!is_armed(nm)) {
-    return true;
-  }
-
   assert(nm->is_osr_method(), "Should not reach here");
   log_trace(nmethod, barrier)("Running osr nmethod entry barrier: " PTR_FORMAT, p2i(nm));
   bool result = nmethod_entry_barrier(nm);

src/hotspot/share/interpreter/linkResolver.cpp

@@ -1810,7 +1810,7 @@ void LinkResolver::resolve_invokedynamic(CallInfo& result, const constantPoolHan
   // the interpreter or runtime performs a serialized check of
   // the relevant ResolvedIndyEntry::method field.  This is done by the caller
   // of this method, via CPC::set_dynamic_call, which uses
-  // a lock to do the final serialization of updates
+  // an ObjectLocker to do the final serialization of updates
   // to ResolvedIndyEntry state, including method.
 
   // Log dynamic info to CDS classlist.

src/hotspot/share/jfr/recorder/repository/jfrChunk.cpp

@@ -47,8 +47,6 @@ jlong JfrChunk::nanos_now() {
   const jlong now = seconds * 1000000000 + nanos;
   if (now > last) {
     last = now;
-  } else {
-    ++last;
   }
   return last;
 }