8338139: {ClassLoading,Memory}MXBean::isVerbose methods are inconsistent with their setVerbose methods

Reviewed-by: kevinw
Backport-of: 9775d57168

.jcheck/conf

@@ -9,7 +9,7 @@ warning=issuestitle
 
 [repository]
 tags=(?:jdk-(?:[1-9]([0-9]*)(?:\.(?:0|[1-9][0-9]*)){0,4})(?:\+(?:(?:[0-9]+))|(?:-ga)))|(?:jdk[4-9](?:u\d{1,3})?-(?:(?:b\d{2,3})|(?:ga)))|(?:hs\d\d(?:\.\d{1,2})?-b\d\d)
-branches=
+branches=.*
 
 [census]
 version=0

make/conf/version-numbers.conf

@@ -39,4 +39,4 @@ DEFAULT_VERSION_CLASSFILE_MINOR=0
 DEFAULT_VERSION_DOCS_API_SINCE=11
 DEFAULT_ACCEPTABLE_BOOT_VERSIONS="22 23"
 DEFAULT_JDK_SOURCE_TARGET_VERSION=23
-DEFAULT_PROMOTED_VERSION_PRE=ea
+DEFAULT_PROMOTED_VERSION_PRE=

make/jdk/src/classes/build/tools/intpoly/FieldGen.java

@@ -778,7 +778,7 @@ public class FieldGen {
         result.appendLine("}");
 
         result.appendLine("@Override");
-        result.appendLine("protected int mult(long[] a, long[] b, long[] r) {");
+        result.appendLine("protected void mult(long[] a, long[] b, long[] r) {");
         result.incrIndent();
         for (int i = 0; i < 2 * params.getNumLimbs() - 1; i++) {
             result.appendIndent();
@@ -804,9 +804,6 @@ public class FieldGen {
             }
         }
         result.append(");\n");
-        result.appendIndent();
-        result.append("return 0;");
-        result.appendLine();
         result.decrIndent();
         result.appendLine("}");
 
@@ -836,7 +833,7 @@ public class FieldGen {
         //      }
         //  }
         result.appendLine("@Override");
-        result.appendLine("protected int square(long[] a, long[] r) {");
+        result.appendLine("protected void square(long[] a, long[] r) {");
         result.incrIndent();
         for (int i = 0; i < 2 * params.getNumLimbs() - 1; i++) {
             result.appendIndent();
@@ -877,9 +874,6 @@ public class FieldGen {
             }
         }
         result.append(");\n");
-        result.appendIndent();
-        result.append("return 0;");
-        result.appendLine();
         result.decrIndent();
         result.appendLine("}");
 

make/jdk/src/classes/build/tools/taglet/SealedGraph.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 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
@@ -107,7 +107,7 @@ public final class SealedGraph implements Taglet {
             throw new RuntimeException(e);
         }
 
-        String simpleTypeName = element.getSimpleName().toString();
+        String simpleTypeName = packagelessCanonicalName(typeElement).replace('.', '/');
         String imageFile = simpleTypeName + "-sealed-graph.svg";
         int thumbnailHeight = 100; // also appears in the stylesheet
         String hoverImage = "<span>"
@@ -315,14 +315,14 @@ public final class SealedGraph implements Taglet {
                 case MEMBER -> packageName((TypeElement) element.getEnclosingElement());
             };
         }
+    }
 
-        private static String packagelessCanonicalName(TypeElement element) {
-            String result = element.getSimpleName().toString();
-            while (element.getNestingKind() == NestingKind.MEMBER) {
-                element = (TypeElement) element.getEnclosingElement();
-                result = element.getSimpleName().toString() + '.' + result;
-            }
-            return result;
+    private static String packagelessCanonicalName(TypeElement element) {
+        String result = element.getSimpleName().toString();
+        while (element.getNestingKind() == NestingKind.MEMBER) {
+            element = (TypeElement) element.getEnclosingElement();
+            result = element.getSimpleName().toString() + '.' + result;
         }
+        return result;
     }
 }

src/hotspot/cpu/x86/stubGenerator_x86_64_poly_mont.cpp

@@ -249,7 +249,6 @@ address StubGenerator::generate_intpoly_montgomeryMult_P256() {
   const Register tmp     = r9;
 
   montgomeryMultiply(aLimbs, bLimbs, rLimbs, tmp, _masm);
-  __ mov64(rax, 0x1); // Return 1 (Fig. 5, Step 6 [1] skipped in montgomeryMultiply)
 
   __ leave();
   __ ret(0);

src/hotspot/share/c1/c1_RangeCheckElimination.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 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
@@ -483,14 +483,14 @@ void RangeCheckEliminator::in_block_motion(BlockBegin *block, AccessIndexedList
 
           if (c) {
             jint value = c->type()->as_IntConstant()->value();
-            if (value != min_jint) {
-              if (ao->op() == Bytecodes::_isub) {
-                value = -value;
-              }
+            if (ao->op() == Bytecodes::_iadd) {
               base = java_add(base, value);
-              last_integer = base;
-              last_instruction = other;
+            } else {
+              assert(ao->op() == Bytecodes::_isub, "unexpected bytecode");
+              base = java_subtract(base, value);
             }
+            last_integer = base;
+            last_instruction = other;
             index = other;
           } else {
             break;

src/hotspot/share/classfile/classLoaderDataGraph.cpp

@@ -241,9 +241,14 @@ 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.
@@ -251,12 +256,8 @@ class ClassLoaderDataGraphIteratorBase : public StackObj {
                             // 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 @@ public:
       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;
@@ -278,9 +275,6 @@ public:
   }
 };
 
-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()) {
@@ -288,13 +282,6 @@ void ClassLoaderDataGraph::loaded_cld_do(CLDClosure* cl) {
   }
 }
 
-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);
   }
 }
@@ -346,7 +345,7 @@ 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();
@@ -354,26 +353,28 @@ void ClassLoaderDataGraph::verify_dictionary() {
   }
 }
 
-#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/symbolTable.cpp

@@ -344,8 +344,23 @@ Symbol* SymbolTable::lookup_common(const char* name,
   return sym;
 }
 
+// Symbols should represent entities from the constant pool that are
+// limited to <64K in length, but usage errors creep in allowing Symbols
+// to be used for arbitrary strings. For debug builds we will assert if
+// a string is too long, whereas product builds will truncate it.
+static int check_length(const char* name, int len) {
+  assert(len <= Symbol::max_length(),
+         "String length %d exceeds the maximum Symbol length of %d", len, Symbol::max_length());
+  if (len > Symbol::max_length()) {
+    warning("A string \"%.80s ... %.80s\" exceeds the maximum Symbol "
+            "length of %d and has been truncated", name, (name + len - 80), Symbol::max_length());
+    len = Symbol::max_length();
+  }
+  return len;
+}
+
 Symbol* SymbolTable::new_symbol(const char* name, int len) {
-  assert(len <= Symbol::max_length(), "sanity");
+  len = check_length(name, len);
   unsigned int hash = hash_symbol(name, len, _alt_hash);
   Symbol* sym = lookup_common(name, len, hash);
   if (sym == nullptr) {
@@ -485,6 +500,7 @@ void SymbolTable::new_symbols(ClassLoaderData* loader_data, const constantPoolHa
   for (int i = 0; i < names_count; i++) {
     const char *name = names[i];
     int len = lengths[i];
+    assert(len <= Symbol::max_length(), "must be - these come from the constant pool");
     unsigned int hash = hashValues[i];
     assert(lookup_shared(name, len, hash) == nullptr, "must have checked already");
     Symbol* sym = do_add_if_needed(name, len, hash, is_permanent);
@@ -494,6 +510,7 @@ void SymbolTable::new_symbols(ClassLoaderData* loader_data, const constantPoolHa
 }
 
 Symbol* SymbolTable::do_add_if_needed(const char* name, int len, uintx hash, bool is_permanent) {
+  assert(len <= Symbol::max_length(), "caller should have ensured this");
   SymbolTableLookup lookup(name, len, hash);
   SymbolTableGet stg;
   bool clean_hint = false;
@@ -542,7 +559,7 @@ Symbol* SymbolTable::do_add_if_needed(const char* name, int len, uintx hash, boo
 
 Symbol* SymbolTable::new_permanent_symbol(const char* name) {
   unsigned int hash = 0;
-  int len = (int)strlen(name);
+  int len = check_length(name, (int)strlen(name));
   Symbol* sym = SymbolTable::lookup_only(name, len, hash);
   if (sym == nullptr) {
     sym = do_add_if_needed(name, len, hash, /* is_permanent */ true);

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/vmIntrinsics.hpp

@@ -529,8 +529,8 @@ class methodHandle;
   /* support for sun.security.util.math.intpoly.MontgomeryIntegerPolynomialP256 */                                      \
   do_class(sun_security_util_math_intpoly_MontgomeryIntegerPolynomialP256, "sun/security/util/math/intpoly/MontgomeryIntegerPolynomialP256")  \
   do_intrinsic(_intpoly_montgomeryMult_P256, sun_security_util_math_intpoly_MontgomeryIntegerPolynomialP256, intPolyMult_name, intPolyMult_signature, F_R) \
-  do_name(intPolyMult_name, "mult")                                                                                     \
-  do_signature(intPolyMult_signature, "([J[J[J)I")                                                                      \
+  do_name(intPolyMult_name, "multImpl")                                                                                     \
+  do_signature(intPolyMult_signature, "([J[J[J)V")                                                                      \
                                                                                                                         \
   do_class(sun_security_util_math_intpoly_IntegerPolynomial, "sun/security/util/math/intpoly/IntegerPolynomial")        \
   do_intrinsic(_intpoly_assign, sun_security_util_math_intpoly_IntegerPolynomial, intPolyAssign_name, intPolyAssign_signature, F_S) \

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/compiler/compilerDirectives.cpp

@@ -761,7 +761,7 @@ DirectiveSet* DirectivesStack::getMatchingDirective(const methodHandle& method,
       if (dir->is_default_directive() || dir->match(method)) {
         match = dir->get_for(comp);
         assert(match != nullptr, "Consistency");
-        if (match->EnableOption) {
+        if (match->EnableOption || dir->is_default_directive()) {
           // The directiveSet for this compile is also enabled -> success
           dir->inc_refcount();
           break;

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/gc/shared/gcVMOperations.cpp

@@ -132,7 +132,7 @@ bool VM_GC_Operation::doit_prologue() {
 void VM_GC_Operation::doit_epilogue() {
   // GC thread root traversal likely used OopMapCache a lot, which
   // might have created lots of old entries. Trigger the cleanup now.
-  OopMapCache::trigger_cleanup();
+  OopMapCache::try_trigger_cleanup();
   if (Universe::has_reference_pending_list()) {
     Heap_lock->notify_all();
   }

src/hotspot/share/gc/shenandoah/shenandoahVMOperations.cpp

@@ -44,7 +44,7 @@ void VM_ShenandoahOperation::doit_epilogue() {
   assert(!ShenandoahHeap::heap()->has_gc_state_changed(), "GC State was not synchronized to java threads.");
   // GC thread root traversal likely used OopMapCache a lot, which
   // might have created lots of old entries. Trigger the cleanup now.
-  OopMapCache::trigger_cleanup();
+  OopMapCache::try_trigger_cleanup();
 }
 
 bool VM_ShenandoahReferenceOperation::doit_prologue() {

src/hotspot/share/gc/x/xDriver.cpp

@@ -134,7 +134,7 @@ public:
 
     // GC thread root traversal likely used OopMapCache a lot, which
     // might have created lots of old entries. Trigger the cleanup now.
-    OopMapCache::trigger_cleanup();
+    OopMapCache::try_trigger_cleanup();
   }
 
   bool gc_locked() const {

src/hotspot/share/gc/z/zDirector.cpp

@@ -524,6 +524,10 @@ static bool rule_major_allocation_rate(const ZDirectorStats& stats) {
 }
 
 static double calculate_young_to_old_worker_ratio(const ZDirectorStats& stats) {
+  if (!stats._old_stats._cycle._is_time_trustable) {
+    return 1.0;
+  }
+
   const double young_gc_time = gc_time(stats._young_stats);
   const double old_gc_time = gc_time(stats._old_stats);
   const size_t reclaimed_per_young_gc = stats._young_stats._stat_heap._reclaimed_avg;

src/hotspot/share/gc/z/zGeneration.cpp

@@ -456,7 +456,7 @@ public:
 
     // GC thread root traversal likely used OopMapCache a lot, which
     // might have created lots of old entries. Trigger the cleanup now.
-    OopMapCache::trigger_cleanup();
+    OopMapCache::try_trigger_cleanup();
   }
 
   bool success() const {

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/interpreter/oopMapCache.cpp

@@ -66,9 +66,6 @@ class OopMapCacheEntry: private InterpreterOopMap {
  public:
   OopMapCacheEntry() : InterpreterOopMap() {
     _next = nullptr;
-#ifdef ASSERT
-    _resource_allocate_bit_mask = false;
-#endif
   }
 };
 
@@ -177,9 +174,13 @@ class VerifyClosure : public OffsetClosure {
 
 InterpreterOopMap::InterpreterOopMap() {
   initialize();
-#ifdef ASSERT
-  _resource_allocate_bit_mask = true;
-#endif
+}
+
+InterpreterOopMap::~InterpreterOopMap() {
+  if (has_valid_mask() && mask_size() > small_mask_limit) {
+    assert(_bit_mask[0] != 0, "should have pointer to C heap");
+    FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
+  }
 }
 
 bool InterpreterOopMap::is_empty() const {
@@ -399,37 +400,24 @@ void OopMapCacheEntry::deallocate(OopMapCacheEntry* const entry) {
 
 // Implementation of OopMapCache
 
-void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {
-  assert(_resource_allocate_bit_mask,
-    "Should not resource allocate the _bit_mask");
-  assert(from->has_valid_mask(),
-    "Cannot copy entry with an invalid mask");
+void InterpreterOopMap::copy_from(const OopMapCacheEntry* src) {
+  // The expectation is that this InterpreterOopMap is recently created
+  // and empty. It is used to get a copy of a cached entry.
+  assert(!has_valid_mask(), "InterpreterOopMap object can only be filled once");
+  assert(src->has_valid_mask(), "Cannot copy entry with an invalid mask");
 
-  set_method(from->method());
-  set_bci(from->bci());
-  set_mask_size(from->mask_size());
-  set_expression_stack_size(from->expression_stack_size());
-  _num_oops = from->num_oops();
+  set_method(src->method());
+  set_bci(src->bci());
+  set_mask_size(src->mask_size());
+  set_expression_stack_size(src->expression_stack_size());
+  _num_oops = src->num_oops();
 
   // Is the bit mask contained in the entry?
-  if (from->mask_size() <= small_mask_limit) {
-    memcpy((void *)_bit_mask, (void *)from->_bit_mask,
-      mask_word_size() * BytesPerWord);
+  if (src->mask_size() <= small_mask_limit) {
+    memcpy(_bit_mask, src->_bit_mask, mask_word_size() * BytesPerWord);
   } else {
-    // The expectation is that this InterpreterOopMap is a recently created
-    // and empty. It is used to get a copy of a cached entry.
-    // If the bit mask has a value, it should be in the
-    // resource area.
-    assert(_bit_mask[0] == 0 ||
-      Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
-      "The bit mask should have been allocated from a resource area");
-    // Allocate the bit_mask from a Resource area for performance.  Allocating
-    // from the C heap as is done for OopMapCache has a significant
-    // performance impact.
-    _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());
-    assert(_bit_mask[0] != 0, "bit mask was not allocated");
-    memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],
-      mask_word_size() * BytesPerWord);
+    _bit_mask[0] = (uintptr_t) NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
+    memcpy((void*) _bit_mask[0], (void*) src->_bit_mask[0], mask_word_size() * BytesPerWord);
   }
 }
 
@@ -516,7 +504,7 @@ void OopMapCache::lookup(const methodHandle& method,
     for (int i = 0; i < _probe_depth; i++) {
       OopMapCacheEntry *entry = entry_at(probe + i);
       if (entry != nullptr && !entry->is_empty() && entry->match(method, bci)) {
-        entry_for->resource_copy(entry);
+        entry_for->copy_from(entry);
         assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
         log_debug(interpreter, oopmap)("- found at hash %d", probe + i);
         return;
@@ -530,7 +518,7 @@ void OopMapCache::lookup(const methodHandle& method,
   OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
   tmp->initialize();
   tmp->fill(method, bci);
-  entry_for->resource_copy(tmp);
+  entry_for->copy_from(tmp);
 
   if (method->should_not_be_cached()) {
     // It is either not safe or not a good idea to cache this Method*
@@ -592,10 +580,13 @@ bool OopMapCache::has_cleanup_work() {
   return Atomic::load(&_old_entries) != nullptr;
 }
 
-void OopMapCache::trigger_cleanup() {
-  if (has_cleanup_work()) {
-    MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
+void OopMapCache::try_trigger_cleanup() {
+  // See we can take the lock for the notification without blocking.
+  // This allows triggering the cleanup from GC paths, that can hold
+  // the service lock for e.g. oop iteration in service thread.
+  if (has_cleanup_work() && Service_lock->try_lock_without_rank_check()) {
     Service_lock->notify_all();
+    Service_lock->unlock();
   }
 }
 
@@ -628,7 +619,7 @@ void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, Inter
   tmp->initialize();
   tmp->fill(method, bci);
   if (tmp->has_valid_mask()) {
-    entry->resource_copy(tmp);
+    entry->copy_from(tmp);
   }
   OopMapCacheEntry::deallocate(tmp);
 }

src/hotspot/share/interpreter/oopMapCache.hpp

@@ -36,13 +36,14 @@
 // OopMapCache's are allocated lazily per InstanceKlass.
 
 // The oopMap (InterpreterOopMap) is stored as a bit mask. If the
-// bit_mask can fit into two words it is stored in
+// bit_mask can fit into four words it is stored in
 // the _bit_mask array, otherwise it is allocated on the heap.
 // For OopMapCacheEntry the bit_mask is allocated in the C heap
 // because these entries persist between garbage collections.
-// For InterpreterOopMap the bit_mask is allocated in
-// a resource area for better performance.  InterpreterOopMap
-// should only be created and deleted during same garbage collection.
+// For InterpreterOopMap the bit_mask is allocated in the C heap
+// to avoid issues with allocations from the resource area that have
+// to live accross the oop closure. InterpreterOopMap should only be
+// created and deleted during the same garbage collection.
 //
 // If ENABBLE_ZAP_DEAD_LOCALS is defined, two bits are used
 // per entry instead of one. In all cases,
@@ -95,9 +96,6 @@ class InterpreterOopMap: ResourceObj {
                                   // access it without using trickery in
                                   // method bit_mask().
   int            _num_oops;
-#ifdef ASSERT
-  bool _resource_allocate_bit_mask;
-#endif
 
   // access methods
   Method*        method() const                  { return _method; }
@@ -128,12 +126,13 @@ class InterpreterOopMap: ResourceObj {
 
  public:
   InterpreterOopMap();
+  ~InterpreterOopMap();
 
-  // Copy the OopMapCacheEntry in parameter "from" into this
-  // InterpreterOopMap.  If the _bit_mask[0] in "from" points to
-  // allocated space (i.e., the bit mask was to large to hold
-  // in-line), allocate the space from a Resource area.
-  void resource_copy(OopMapCacheEntry* from);
+  // Copy the OopMapCacheEntry in parameter "src" into this
+  // InterpreterOopMap.  If the _bit_mask[0] in "src" points to
+  // allocated space (i.e., the bit mask was too large to hold
+  // in-line), allocate the space from the C heap.
+  void copy_from(const OopMapCacheEntry* src);
 
   void iterate_oop(OffsetClosure* oop_closure) const;
   void print() const;
@@ -183,8 +182,8 @@ class OopMapCache : public CHeapObj<mtClass> {
   // Check if we need to clean up old entries
   static bool has_cleanup_work();
 
-  // Request cleanup if work is needed
-  static void trigger_cleanup();
+  // Request cleanup if work is needed and notification is currently possible
+  static void try_trigger_cleanup();
 
   // Clean up the old entries
   static void cleanup();

src/hotspot/share/jfr/jni/jfrJniMethod.cpp

@@ -30,6 +30,7 @@
 #include "jfr/recorder/jfrRecorder.hpp"
 #include "jfr/recorder/checkpoint/jfrMetadataEvent.hpp"
 #include "jfr/recorder/checkpoint/types/traceid/jfrTraceId.inline.hpp"
+#include "jfr/recorder/repository/jfrChunk.hpp"
 #include "jfr/recorder/repository/jfrRepository.hpp"
 #include "jfr/recorder/repository/jfrChunkRotation.hpp"
 #include "jfr/recorder/repository/jfrChunkWriter.hpp"
@@ -425,3 +426,7 @@ JVM_END
 JVM_ENTRY_NO_ENV(void, jfr_unregister_stack_filter(JNIEnv* env,  jclass jvm, jlong id))
   JfrStackFilterRegistry::remove(id);
 JVM_END
+
+NO_TRANSITION(jlong, jfr_nanos_now(JNIEnv* env, jclass jvm))
+  return JfrChunk::nanos_now();
+NO_TRANSITION_END

src/hotspot/share/jfr/jni/jfrJniMethod.hpp

@@ -165,6 +165,8 @@ jlong JNICALL jfr_register_stack_filter(JNIEnv* env, jclass jvm, jobjectArray cl
 
 jlong JNICALL jfr_unregister_stack_filter(JNIEnv* env, jclass jvm, jlong id);
 
+jlong JNICALL jfr_nanos_now(JNIEnv* env, jclass jvm);
+
 #ifdef __cplusplus
 }
 #endif

src/hotspot/share/jfr/jni/jfrJniMethodRegistration.cpp

@@ -100,7 +100,8 @@ JfrJniMethodRegistration::JfrJniMethodRegistration(JNIEnv* env) {
       (char*)"hostTotalSwapMemory", (char*)"()J", (void*) jfr_host_total_swap_memory,
       (char*)"emitDataLoss", (char*)"(J)V", (void*)jfr_emit_data_loss,
       (char*)"registerStackFilter", (char*)"([Ljava/lang/String;[Ljava/lang/String;)J", (void*)jfr_register_stack_filter,
-      (char*)"unregisterStackFilter", (char*)"(J)V", (void*)jfr_unregister_stack_filter
+      (char*)"unregisterStackFilter", (char*)"(J)V", (void*)jfr_unregister_stack_filter,
+      (char*)"nanosNow", (char*)"()J", (void*)jfr_nanos_now
     };
 
     const size_t method_array_length = sizeof(method) / sizeof(JNINativeMethod);

src/hotspot/share/jfr/leakprofiler/checkpoint/objectSampleCheckpoint.cpp

@@ -36,6 +36,7 @@
 #include "jfr/recorder/checkpoint/types/traceid/jfrTraceId.inline.hpp"
 #include "jfr/recorder/service/jfrOptionSet.hpp"
 #include "jfr/recorder/stacktrace/jfrStackTraceRepository.hpp"
+#include "jfr/recorder/storage/jfrReferenceCountedStorage.hpp"
 #include "jfr/support/jfrKlassUnloading.hpp"
 #include "jfr/support/jfrMethodLookup.hpp"
 #include "jfr/utilities/jfrHashtable.hpp"
@@ -272,11 +273,30 @@ static void install_stack_traces(const ObjectSampler* sampler) {
   iterate_samples(installer);
 }
 
+// Resets the blob write states from the previous epoch.
+static void reset_blob_write_state(const ObjectSampler* sampler, JavaThread* jt) {
+  assert(sampler != nullptr, "invariant");
+  const ObjectSample* sample = sampler->last_resolved();
+  while (sample != nullptr) {
+    if (sample->has_stacktrace()) {
+      sample->stacktrace()->reset_write_state();
+    }
+    if (sample->has_thread()) {
+      sample->thread()->reset_write_state();
+    }
+    if (sample->has_type_set()) {
+      sample->type_set()->reset_write_state();
+    }
+    sample = sample->next();
+  }
+}
+
 void ObjectSampleCheckpoint::on_rotation(const ObjectSampler* sampler) {
   assert(sampler != nullptr, "invariant");
   assert(LeakProfiler::is_running(), "invariant");
   JavaThread* const thread = JavaThread::current();
   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(thread);)
+  reset_blob_write_state(sampler, thread);
   if (!ObjectSampler::has_unresolved_entry()) {
     return;
   }
@@ -326,38 +346,34 @@ void ObjectSampleCheckpoint::write_stacktrace(const JfrStackTrace* trace, JfrChe
   }
 }
 
-static void write_blob(const JfrBlobHandle& blob, JfrCheckpointWriter& writer, bool reset) {
-  if (reset) {
-    blob->reset_write_state();
-    return;
-  }
+static void write_blob(const JfrBlobHandle& blob, JfrCheckpointWriter& writer) {
   blob->exclusive_write(writer);
 }
 
-static void write_type_set_blob(const ObjectSample* sample, JfrCheckpointWriter& writer, bool reset) {
+static void write_type_set_blob(const ObjectSample* sample, JfrCheckpointWriter& writer) {
   if (sample->has_type_set()) {
-    write_blob(sample->type_set(), writer, reset);
+    write_blob(sample->type_set(), writer);
   }
 }
 
-static void write_thread_blob(const ObjectSample* sample, JfrCheckpointWriter& writer, bool reset) {
+static void write_thread_blob(const ObjectSample* sample, JfrCheckpointWriter& writer) {
   assert(sample->has_thread(), "invariant");
   if (sample->is_virtual_thread() || has_thread_exited(sample->thread_id())) {
-    write_blob(sample->thread(), writer, reset);
+    write_blob(sample->thread(), writer);
   }
 }
 
-static void write_stacktrace_blob(const ObjectSample* sample, JfrCheckpointWriter& writer, bool reset) {
+static void write_stacktrace_blob(const ObjectSample* sample, JfrCheckpointWriter& writer) {
   if (sample->has_stacktrace()) {
-    write_blob(sample->stacktrace(), writer, reset);
+    write_blob(sample->stacktrace(), writer);
   }
 }
 
-static void write_blobs(const ObjectSample* sample, JfrCheckpointWriter& writer, bool reset) {
+static void write_blobs(const ObjectSample* sample, JfrCheckpointWriter& writer) {
   assert(sample != nullptr, "invariant");
-  write_stacktrace_blob(sample, writer, reset);
-  write_thread_blob(sample, writer, reset);
-  write_type_set_blob(sample, writer, reset);
+  write_stacktrace_blob(sample, writer);
+  write_thread_blob(sample, writer);
+  write_type_set_blob(sample, writer);
 }
 
 class BlobWriter {
@@ -365,18 +381,14 @@ class BlobWriter {
   const ObjectSampler* _sampler;
   JfrCheckpointWriter& _writer;
   const jlong _last_sweep;
-  bool _reset;
  public:
   BlobWriter(const ObjectSampler* sampler, JfrCheckpointWriter& writer, jlong last_sweep) :
-    _sampler(sampler), _writer(writer), _last_sweep(last_sweep), _reset(false)  {}
+    _sampler(sampler), _writer(writer), _last_sweep(last_sweep) {}
   void sample_do(ObjectSample* sample) {
     if (sample->is_alive_and_older_than(_last_sweep)) {
-      write_blobs(sample, _writer, _reset);
+      write_blobs(sample, _writer);
     }
   }
-  void set_reset() {
-    _reset = true;
-  }
 };
 
 static void write_sample_blobs(const ObjectSampler* sampler, bool emit_all, Thread* thread) {
@@ -385,9 +397,6 @@ static void write_sample_blobs(const ObjectSampler* sampler, bool emit_all, Thre
   JfrCheckpointWriter writer(thread, false);
   BlobWriter cbw(sampler, writer, last_sweep);
   iterate_samples(cbw, true);
-  // reset blob write states
-  cbw.set_reset();
-  iterate_samples(cbw, true);
 }
 
 void ObjectSampleCheckpoint::write(const ObjectSampler* sampler, EdgeStore* edge_store, bool emit_all, Thread* thread) {
@@ -403,67 +412,17 @@ void ObjectSampleCheckpoint::write(const ObjectSampler* sampler, EdgeStore* edge
   }
 }
 
-// A linked list of saved type set blobs for the epoch.
-// The link consist of a reference counted handle.
-static JfrBlobHandle saved_type_set_blobs;
-
-static void release_state_for_previous_epoch() {
-  // decrements the reference count and the list is reinitialized
-  saved_type_set_blobs = JfrBlobHandle();
-}
-
-class BlobInstaller {
- public:
-  ~BlobInstaller() {
-    release_state_for_previous_epoch();
-  }
-  void sample_do(ObjectSample* sample) {
-    if (!sample->is_dead()) {
-      sample->set_type_set(saved_type_set_blobs);
-    }
-  }
-};
-
-static void install_type_set_blobs() {
-  if (saved_type_set_blobs.valid()) {
-    BlobInstaller installer;
-    iterate_samples(installer);
-  }
-}
-
-static void save_type_set_blob(JfrCheckpointWriter& writer) {
-  assert(writer.has_data(), "invariant");
-  const JfrBlobHandle blob = writer.copy();
-  if (saved_type_set_blobs.valid()) {
-    saved_type_set_blobs->set_next(blob);
-  } else {
-    saved_type_set_blobs = blob;
-  }
-}
-
 // This routine has exclusive access to the sampler instance on entry.
-void ObjectSampleCheckpoint::on_type_set(JfrCheckpointWriter& writer) {
+void ObjectSampleCheckpoint::on_type_set(JavaThread* jt) {
   assert(LeakProfiler::is_running(), "invariant");
   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(JavaThread::current());)
   assert(ClassLoaderDataGraph_lock->owned_by_self(), "invariant");
   if (!ObjectSampler::has_unresolved_entry()) {
     return;
   }
-  const ObjectSample* const last = ObjectSampler::sampler()->last();
+  ObjectSample* const last = ObjectSampler::sampler()->last();
   assert(last != nullptr, "invariant");
   assert(last != ObjectSampler::sampler()->last_resolved(), "invariant");
-  if (writer.has_data()) {
-    save_type_set_blob(writer);
-  }
-  install_type_set_blobs();
+  JfrReferenceCountedStorage::install(last, ObjectSampler::sampler()->last_resolved());
   ObjectSampler::sampler()->set_last_resolved(last);
 }
-
-// This routine does NOT have exclusive access to the sampler instance on entry.
-void ObjectSampleCheckpoint::on_type_set_unload(JfrCheckpointWriter& writer) {
-  assert(LeakProfiler::is_running(), "invariant");
-  assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
-  if (writer.has_data() && ObjectSampler::has_unresolved_entry()) {
-    save_type_set_blob(writer);
-  }
-}

src/hotspot/share/jfr/leakprofiler/checkpoint/objectSampleCheckpoint.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 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
@@ -50,8 +50,7 @@ class ObjectSampleCheckpoint : AllStatic {
   static void write(const ObjectSampler* sampler, EdgeStore* edge_store, bool emit_all, Thread* thread);
   static void clear();
  public:
-  static void on_type_set(JfrCheckpointWriter& writer);
-  static void on_type_set_unload(JfrCheckpointWriter& writer);
+  static void on_type_set(JavaThread* jt);
   static void on_thread_exit(traceid tid);
   static void on_rotation(const ObjectSampler* sampler);
 };

src/hotspot/share/jfr/leakprofiler/sampling/objectSample.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 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
@@ -233,7 +233,7 @@ class ObjectSample : public JfrCHeapObj {
     return _type_set.valid();
   }
 
-  void set_type_set(const JfrBlobHandle& ref) {
+  void install_type_set(const JfrBlobHandle& ref) {
     if (_type_set != ref) {
       if (_type_set.valid()) {
         _type_set->set_next(ref);

src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointManager.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 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
@@ -37,6 +37,7 @@
 #include "jfr/recorder/service/jfrOptionSet.hpp"
 #include "jfr/recorder/storage/jfrEpochStorage.inline.hpp"
 #include "jfr/recorder/storage/jfrMemorySpace.inline.hpp"
+#include "jfr/recorder/storage/jfrReferenceCountedStorage.hpp"
 #include "jfr/recorder/storage/jfrStorageUtils.inline.hpp"
 #include "jfr/recorder/stringpool/jfrStringPool.hpp"
 #include "jfr/support/jfrDeprecationManager.hpp"
@@ -589,12 +590,14 @@ void JfrCheckpointManager::clear_type_set() {
     MutexLocker module_lock(Module_lock);
     JfrTypeSet::clear(&writer, &leakp_writer);
   }
-  JfrDeprecationManager::on_type_set(leakp_writer, nullptr, thread);
-  // We placed a blob in the Deprecated subsystem by moving the information
-  // from the leakp writer. For the real writer, the data will not be
-  // committed, because the JFR system is yet to be started.
-  // Therefore, the writer is cancelled before its destructor is run,
-  // to avoid writing unnecessary information into the checkpoint system.
+  JfrAddRefCountedBlob add_blob(leakp_writer);
+  JfrDeprecationManager::on_type_set(nullptr, thread);
+  // We installed a blob in the JfrReferenceCountedStorage subsystem
+  // by moving the information from the leakp writer.
+  // For the real writer, the data will not be committed,
+  // because the JFR system is yet to be started.
+  // Therefore, we cancel the writer before its destructor is run
+  // to avoid writing invalid information into the checkpoint system.
   writer.cancel();
 }
 
@@ -613,11 +616,11 @@ void JfrCheckpointManager::write_type_set() {
       MutexLocker module_lock(thread, Module_lock);
       JfrTypeSet::serialize(&writer, &leakp_writer, false, false);
     }
+    JfrAddRefCountedBlob add_blob(leakp_writer);
     if (LeakProfiler::is_running()) {
-      ObjectSampleCheckpoint::on_type_set(leakp_writer);
+      ObjectSampleCheckpoint::on_type_set(thread);
     }
-    // Place this call after ObjectSampleCheckpoint::on_type_set.
-    JfrDeprecationManager::on_type_set(leakp_writer, _chunkwriter, thread);
+    JfrDeprecationManager::on_type_set(_chunkwriter, thread);
   }
   write();
 }
@@ -626,10 +629,7 @@ void JfrCheckpointManager::on_unloading_classes() {
   assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
   JfrCheckpointWriter writer(Thread::current());
   JfrTypeSet::on_unloading_classes(&writer);
-  if (LeakProfiler::is_running()) {
-    ObjectSampleCheckpoint::on_type_set_unload(writer);
-  }
-  JfrDeprecationManager::on_type_set_unload(writer);
+  JfrAddRefCountedBlob add_blob(writer, false /* move */, false /* reset */);
 }
 
 static size_t flush_type_set(Thread* thread) {

src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointWriter.hpp

@@ -54,6 +54,7 @@ struct JfrCheckpointContext {
 };
 
 class JfrCheckpointWriter : public JfrCheckpointWriterBase {
+  friend class JfrAddRefCountedBlob;
   friend class JfrCheckpointManager;
   friend class JfrDeprecationManager;
   friend class JfrSerializerRegistration;

src/hotspot/share/jfr/recorder/checkpoint/types/jfrTypeSet.cpp

@@ -310,7 +310,9 @@ static void set_serialized(const T* ptr) {
   assert(ptr != nullptr, "invariant");
   if (current_epoch()) {
     CLEAR_THIS_EPOCH_CLEARED_BIT(ptr);
+    assert(!IS_THIS_EPOCH_CLEARED_BIT_SET(ptr), "invariant");
   }
+  assert(IS_PREVIOUS_EPOCH_CLEARED_BIT_SET(ptr), "invariant");
   SET_SERIALIZED(ptr);
   assert(IS_SERIALIZED(ptr), "invariant");
 }
@@ -929,9 +931,11 @@ void set_serialized<Method>(MethodPtr method) {
   assert(method != nullptr, "invariant");
   if (current_epoch()) {
     CLEAR_THIS_EPOCH_METHOD_CLEARED_BIT(method);
+    assert(!IS_THIS_EPOCH_METHOD_CLEARED_BIT_SET(method), "invariant");
   }
   assert(unloading() ? true : METHOD_IS_NOT_SERIALIZED(method), "invariant");
   SET_METHOD_SERIALIZED(method);
+  assert(IS_PREVIOUS_EPOCH_METHOD_CLEARED_BIT_SET(method), "invariant");
   assert(METHOD_IS_SERIALIZED(method), "invariant");
 }
 

src/hotspot/share/jfr/recorder/checkpoint/types/jfrTypeSetUtils.hpp

@@ -96,6 +96,8 @@ class ClearArtifact {
     assert(IS_NOT_TRANSIENT(value), "invariant");
     SET_PREVIOUS_EPOCH_CLEARED_BIT(value);
     CLEAR_PREVIOUS_EPOCH_METHOD_AND_CLASS(value);
+    assert(IS_THIS_EPOCH_CLEARED_BIT_SET(value), "invariant");
+    assert(IS_PREVIOUS_EPOCH_CLEARED_BIT_SET(value), "invariant");
     return true;
   }
 };
@@ -111,6 +113,8 @@ class ClearArtifact<const Method*> {
     assert(METHOD_IS_NOT_TRANSIENT(method), "invariant");
     SET_PREVIOUS_EPOCH_METHOD_CLEARED_BIT(method);
     CLEAR_PREVIOUS_EPOCH_METHOD_FLAG(method);
+    assert(IS_THIS_EPOCH_METHOD_CLEARED_BIT_SET(method), "invariant");
+    assert(IS_PREVIOUS_EPOCH_METHOD_CLEARED_BIT_SET(method), "invariant");
     return true;
   }
 };

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 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
@@ -50,22 +50,22 @@ static traceid atomic_inc(traceid volatile* const dest, traceid stride = 1) {
 
 static traceid next_class_id() {
   static volatile traceid class_id_counter = LAST_TYPE_ID + 1; // + 1 is for the void.class primitive
-  return atomic_inc(&class_id_counter) << TRACE_ID_SHIFT;
+  return (atomic_inc(&class_id_counter) << TRACE_ID_SHIFT) | EPOCH_CLEARED_BITS;
 }
 
 static traceid next_module_id() {
   static volatile traceid module_id_counter = 0;
-  return atomic_inc(&module_id_counter) << TRACE_ID_SHIFT;
+  return (atomic_inc(&module_id_counter) << TRACE_ID_SHIFT) | EPOCH_CLEARED_BITS;
 }
 
 static traceid next_package_id() {
   static volatile traceid package_id_counter = 0;
-  return atomic_inc(&package_id_counter) << TRACE_ID_SHIFT;
+  return (atomic_inc(&package_id_counter) << TRACE_ID_SHIFT) | EPOCH_CLEARED_BITS;
 }
 
 static traceid next_class_loader_data_id() {
   static volatile traceid cld_id_counter = 0;
-  return atomic_inc(&cld_id_counter) << TRACE_ID_SHIFT;
+  return (atomic_inc(&cld_id_counter) << TRACE_ID_SHIFT) | EPOCH_CLEARED_BITS;
 }
 
 static bool found_jdk_internal_event_klass = false;
@@ -201,18 +201,18 @@ traceid JfrTraceId::load_raw(jclass jc) {
 // used by CDS / APPCDS as part of "remove_unshareable_info"
 void JfrTraceId::remove(const Klass* k) {
   assert(k != nullptr, "invariant");
-  // Mask off and store the event flags.
+  // Mask off and store the event flags and epoch clear bits.
   // This mechanism will retain the event specific flags
   // in the archive, allowing for event flag restoration
   // when renewing the traceid on klass revival.
-  k->set_trace_id(EVENT_KLASS_MASK(k));
+  k->set_trace_id(EPOCH_CLEARED_BITS | EVENT_KLASS_MASK(k));
 }
 
 // used by CDS / APPCDS as part of "remove_unshareable_info"
 void JfrTraceId::remove(const Method* method) {
   assert(method != nullptr, "invariant");
-  // Clear all bits.
-  method->set_trace_flags(0);
+  // Clear tag bits and set epoch cleared bits.
+  method->set_trace_flags(static_cast<uint16_t>(EPOCH_CLEARED_BITS));
 }
 
 // used by CDS / APPCDS as part of "restore_unshareable_info"

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

@@ -157,9 +157,9 @@ inline traceid JfrTraceIdLoadBarrier::load_leakp(const Klass* klass) {
 
 inline traceid JfrTraceIdLoadBarrier::load_leakp(const Klass* klass, const Method* method) {
   assert(klass != nullptr, "invariant");
-  assert(METHOD_AND_CLASS_USED_THIS_EPOCH(klass), "invariant");
   assert(method != nullptr, "invariant");
   assert(klass == method->method_holder(), "invariant");
+  assert(METHOD_AND_CLASS_USED_THIS_EPOCH(klass), "invariant");
   if (should_tag(method)) {
     // the method is already logically tagged, just like the klass,
     // but because of redefinition, the latest Method*
@@ -174,9 +174,9 @@ inline traceid JfrTraceIdLoadBarrier::load_leakp(const Klass* klass, const Metho
 
 inline traceid JfrTraceIdLoadBarrier::load_leakp_previuos_epoch(const Klass* klass, const Method* method) {
   assert(klass != nullptr, "invariant");
-  assert(METHOD_AND_CLASS_USED_PREVIOUS_EPOCH(klass), "invariant");
   assert(method != nullptr, "invariant");
   assert(klass == method->method_holder(), "invariant");
+  assert(METHOD_AND_CLASS_USED_PREVIOUS_EPOCH(klass), "invariant");
   if (METHOD_FLAG_NOT_USED_PREVIOUS_EPOCH(method)) {
     // the method is already logically tagged, just like the klass,
     // but because of redefinition, the latest Method*

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 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
@@ -48,6 +48,7 @@
 #define EPOCH_0_CLEARED_BIT                       (EPOCH_0_CLEARED_META_BIT << META_SHIFT)
 #define EPOCH_1_CLEARED_META_BIT                  (BIT << 1)
 #define EPOCH_1_CLEARED_BIT                       (EPOCH_1_CLEARED_META_BIT << META_SHIFT)
+#define EPOCH_CLEARED_BITS                        (EPOCH_1_CLEARED_BIT | EPOCH_0_CLEARED_BIT)
 #define LEAKP_META_BIT                            (BIT << 2)
 #define LEAKP_BIT                                 (LEAKP_META_BIT << META_SHIFT)
 #define TRANSIENT_META_BIT                        (BIT << 3)
@@ -136,6 +137,8 @@
 #define IS_TRANSIENT(ptr)                         (TRACE_ID_PREDICATE(ptr, TRANSIENT_BIT))
 #define IS_NOT_TRANSIENT(ptr)                     (!(IS_TRANSIENT(ptr)))
 #define SET_SERIALIZED(ptr)                       (TRACE_ID_META_TAG(ptr, SERIALIZED_META_BIT))
+#define IS_THIS_EPOCH_CLEARED_BIT_SET(ptr)        (TRACE_ID_PREDICATE(ptr, (THIS_EPOCH_BIT << META_SHIFT)))
+#define IS_PREVIOUS_EPOCH_CLEARED_BIT_SET(ptr)    (TRACE_ID_PREDICATE(ptr, (PREVIOUS_EPOCH_BIT << META_SHIFT)))
 #define IS_SERIALIZED(ptr)                        (TRACE_ID_PREDICATE(ptr, SERIALIZED_BIT))
 #define IS_NOT_SERIALIZED(ptr)                    (!(IS_SERIALIZED(ptr)))
 #define SHOULD_TAG(ptr)                           (NOT_USED_THIS_EPOCH(ptr))
@@ -161,5 +164,7 @@
 #define CLEAR_THIS_EPOCH_METHOD_CLEARED_BIT(ptr)  (METHOD_META_MASK_CLEAR(ptr,(~(THIS_EPOCH_BIT))))
 #define IS_THIS_EPOCH_METHOD_CLEARED(ptr)         (METHOD_FLAG_PREDICATE(method, THIS_EPOCH_BIT))
 #define IS_PREVIOUS_EPOCH_METHOD_CLEARED(ptr)     (METHOD_FLAG_PREDICATE(method, PREVIOUS_EPOCH_BIT))
+#define IS_THIS_EPOCH_METHOD_CLEARED_BIT_SET(ptr) (METHOD_FLAG_PREDICATE(ptr, (THIS_EPOCH_BIT << META_SHIFT)))
+#define IS_PREVIOUS_EPOCH_METHOD_CLEARED_BIT_SET(ptr) (METHOD_FLAG_PREDICATE(ptr, (PREVIOUS_EPOCH_BIT << META_SHIFT)))
 
 #endif // SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDMACROS_HPP

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 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
@@ -35,7 +35,7 @@ static const u2 JFR_VERSION_MAJOR = 2;
 static const u2 JFR_VERSION_MINOR = 1;
 
 // strictly monotone
-static jlong nanos_now() {
+jlong JfrChunk::nanos_now() {
   static jlong last = 0;
 
   jlong seconds;
@@ -47,8 +47,6 @@ static jlong nanos_now() {
   const jlong now = seconds * 1000000000 + nanos;
   if (now > last) {
     last = now;
-  } else {
-    ++last;
   }
   return last;
 }
@@ -147,7 +145,7 @@ void JfrChunk::update_start_ticks() {
 }
 
 void JfrChunk::update_start_nanos() {
-  const jlong now = nanos_now();
+  const jlong now = JfrChunk::nanos_now();
   assert(now >= _start_nanos, "invariant");
   assert(now >= _last_update_nanos, "invariant");
   _start_nanos = _last_update_nanos = now;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 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
@@ -34,6 +34,8 @@ const u1 PAD = 0;
 class JfrChunk : public JfrCHeapObj {
   friend class JfrChunkWriter;
   friend class JfrChunkHeadWriter;
+ public:
+   static jlong nanos_now();
  private:
   char* _path;
   int64_t _start_ticks;

src/hotspot/share/jfr/recorder/storage/jfrReferenceCountedStorage.cpp

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 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
+ * 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "jfr/leakprofiler/sampling/objectSampler.hpp"
+#include "jfr/recorder/checkpoint/jfrCheckpointWriter.hpp"
+#include "jfr/recorder/storage/jfrReferenceCountedStorage.hpp"
+#include "jfr/support/jfrDeprecationManager.hpp"
+
+// Currently only two subsystems use type set blobs. Save a blob only if either has an unresolved entry.
+static inline bool save_blob_predicate() {
+  return JfrDeprecationManager::has_unresolved_entry() || ObjectSampler::has_unresolved_entry();
+}
+
+JfrAddRefCountedBlob::JfrAddRefCountedBlob(JfrCheckpointWriter& writer, bool move /* true */, bool reset /* true */) : _reset(reset) {
+  if (writer.has_data()) {
+    if (save_blob_predicate()) {
+      JfrReferenceCountedStorage::save_blob(writer, move);
+    } else if (move) {
+      writer.cancel();
+    }
+  }
+  DEBUG_ONLY(if (reset) JfrReferenceCountedStorage::set_scope();)
+}
+
+JfrAddRefCountedBlob::~JfrAddRefCountedBlob() {
+  if (_reset) {
+    JfrReferenceCountedStorage::reset();
+  }
+}
+
+JfrBlobHandle JfrReferenceCountedStorage::_type_sets = JfrBlobHandle();
+DEBUG_ONLY(bool JfrReferenceCountedStorage::_scope = false;)
+
+void JfrReferenceCountedStorage::save_blob(JfrCheckpointWriter& writer, bool move /* false */) {
+  assert(writer.has_data(), "invariant");
+  const JfrBlobHandle blob = move ? writer.move() : writer.copy();
+  if (_type_sets.valid()) {
+    _type_sets->set_next(blob);
+    return;
+  }
+  _type_sets = blob;
+}
+
+void JfrReferenceCountedStorage::reset() {
+  assert(_scope, "invariant");
+  if (_type_sets.valid()) {
+    _type_sets = JfrBlobHandle();
+  }
+  DEBUG_ONLY(_scope = false;)
+}
+
+#ifdef ASSERT
+void JfrReferenceCountedStorage::set_scope() {
+  assert(!_scope, "invariant");
+  _scope = true;
+}
+#endif

src/hotspot/share/jfr/recorder/storage/jfrReferenceCountedStorage.hpp

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 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
+ * 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.
+ *
+ */
+
+#ifndef SHARE_JFR_RECORDER_STORAGE_JFRREFERENCECOUNTEDSTORAGE_HPP
+#define SHARE_JFR_RECORDER_STORAGE_JFRREFERENCECOUNTEDSTORAGE_HPP
+
+#include "jfr/utilities/jfrBlob.hpp"
+#include "memory/allocation.hpp"
+#include "utilities/macros.hpp"
+
+class JfrCheckpointWriter;
+
+// RAII helper class for adding blobs to the storage.
+class JfrAddRefCountedBlob : public StackObj {
+ private:
+  bool _reset;
+ public:
+  JfrAddRefCountedBlob(JfrCheckpointWriter& writer, bool move = true, bool reset = true);
+  ~JfrAddRefCountedBlob();
+};
+
+// The debug aid 'scope' implies the proper RAII save construct is placed on stack.
+// This is a necessary condition for installing reference counted storage to nodes.
+class JfrReferenceCountedStorage : AllStatic {
+  friend class JfrAddRefCountedBlob;
+ private:
+  static JfrBlobHandle _type_sets; // linked-list of blob handles saved during epoch.
+  DEBUG_ONLY(static bool _scope;)
+
+  static void save_blob(JfrCheckpointWriter& writer, bool move = false);
+  static void reset();
+  DEBUG_ONLY(static void set_scope();)
+
+ public:
+  template <typename T>
+  static void install(T* node, const T* end) {
+    assert(_scope, "invariant");
+    if (_type_sets.valid()) {
+      while (node != end) {
+        node->install_type_set(_type_sets);
+        node = node->next();
+      }
+    }
+  }
+};
+
+#endif // SHARE_JFR_RECORDER_STORAGE_JFRREFERENCECOUNTEDSTORAGE_HPP

src/hotspot/share/jfr/support/jfrDeprecationEventWriter.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2023, 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
@@ -116,8 +116,8 @@ bool JfrDeprecatedStackTraceWriter::process(const JfrDeprecatedEdge* edge) {
   return true;
 }
 
-JfrDeprecatedEventWriter::JfrDeprecatedEventWriter(JfrChunkWriter& cw, bool stacktrace) :
-  _now(JfrTicks::now()),_cw(cw), _for_removal(only_for_removal()), _stacktrace(stacktrace), _did_write(false) {}
+JfrDeprecatedEventWriter::JfrDeprecatedEventWriter(JfrChunkWriter& cw, JfrCheckpointWriter& tsw, bool stacktrace) :
+  _now(JfrTicks::now()),_cw(cw), _tsw(tsw), _for_removal(only_for_removal()), _stacktrace(stacktrace) {}
 
 static size_t calculate_event_size(const JfrDeprecatedEdge* edge, JfrChunkWriter& cw, const JfrTicks& now, bool stacktrace) {
   assert(edge != nullptr, "invariant");
@@ -141,14 +141,31 @@ static void write_event(const JfrDeprecatedEdge* edge, JfrChunkWriter& cw, const
   cw.write(edge->for_removal());
 }
 
+static void write_type_set(const JfrDeprecatedEdge* edge, JfrCheckpointWriter& tsw) {
+  if (!edge->has_type_set()) {
+    return;
+  }
+  edge->type_set()->exclusive_write(tsw);
+}
+
 bool JfrDeprecatedEventWriter::process(const JfrDeprecatedEdge* edge) {
   assert(edge != nullptr, "invariant");
   if (_for_removal && !edge->for_removal()) {
     return true;
   }
-  write_event(edge, _cw,_now, _stacktrace);
-  if (!_did_write) {
-    _did_write = true;
-  }
+  write_event(edge, _cw, _now, _stacktrace);
+  write_type_set(edge, _tsw);
   return true;
 }
+
+JfrDeprecatedEventClear::JfrDeprecatedEventClear() {}
+
+bool JfrDeprecatedEventClear::process(const JfrDeprecatedEdge* edge) {
+  assert(edge != nullptr, "invariant");
+  if (!edge->has_type_set()) {
+    return true;
+  }
+  edge->type_set()->reset_write_state();
+  return true;
+}
+

src/hotspot/share/jfr/support/jfrDeprecationEventWriter.hpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2023, 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
@@ -56,12 +56,17 @@ class JfrDeprecatedEventWriter : public StackObj {
  private:
   JfrTicks _now;
   JfrChunkWriter& _cw;
+  JfrCheckpointWriter& _tsw;
   bool _for_removal;
   bool _stacktrace;
-  bool _did_write;
  public:
-  JfrDeprecatedEventWriter(JfrChunkWriter& cw, bool stacktrace);
-  bool did_write() const { return _did_write; }
+  JfrDeprecatedEventWriter(JfrChunkWriter& cw, JfrCheckpointWriter& tsw, bool stacktrace);
+  bool process(const JfrDeprecatedEdge* edge);
+};
+
+class JfrDeprecatedEventClear : public StackObj {
+ public:
+  JfrDeprecatedEventClear();
   bool process(const JfrDeprecatedEdge* edge);
 };
 

src/hotspot/share/jfr/support/jfrDeprecationManager.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2023, 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
@@ -32,6 +32,7 @@
 #include "jfr/recorder/checkpoint/types/traceid/jfrTraceId.inline.hpp"
 #include "jfr/recorder/repository/jfrChunkWriter.hpp"
 #include "jfr/recorder/stacktrace/jfrStackTraceRepository.hpp"
+#include "jfr/recorder/storage/jfrReferenceCountedStorage.hpp"
 #include "jfr/support/jfrDeprecationEventWriter.hpp"
 #include "jfr/support/jfrDeprecationManager.hpp"
 #include "jfr/support/jfrKlassUnloading.hpp"
@@ -66,6 +67,7 @@ static inline traceid load_traceid(const Method* method) {
 JfrDeprecatedEdge::JfrDeprecatedEdge(const Method* method, Method* sender, int bci, u1 frame_type, JavaThread* jt) :
   _invocation_time(JfrTicks::now()),
   _stacktrace(),
+  _type_set(),
   _next(nullptr),
   _deprecated_ik(method->method_holder()),
   _deprecated_methodid(load_traceid(method)),
@@ -94,11 +96,25 @@ const JfrBlobHandle& JfrDeprecatedEdge::stacktrace() const {
   return _stacktrace;
 }
 
+bool JfrDeprecatedEdge::has_type_set() const {
+  return _type_set.valid();
+}
+
+const JfrBlobHandle& JfrDeprecatedEdge::type_set() const {
+  assert(has_type_set(), "invariant");
+  return _type_set;
+}
+
+void JfrDeprecatedEdge::install_type_set(const JfrBlobHandle& type_set) {
+  assert(!has_type_set(), "invariant");
+  _type_set = type_set;
+}
+
 typedef JfrLinkedList<JfrDeprecatedEdge> DeprecatedEdgeList;
 
 static DeprecatedEdgeList _list; // Newly constructed edges are concurrently added to this list.
 static DeprecatedEdgeList _pending_list; // During epoch rotation (safepoint) entries in _list are moved onto _pending_list
-static DeprecatedEdgeList _resolved_list; // Fully resolved edges (event and stacktrace blobs).
+static DeprecatedEdgeList _resolved_list; // Fully resolved edges (event, stacktrace and typeset blobs).
 
 static JfrDeprecatedEdge* allocate_edge(const Method* method, Method* sender, int bci, u1 frame_type, JavaThread* jt) {
   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(jt);)
@@ -225,10 +241,6 @@ static void transfer_list() {
   }
 }
 
-void JfrDeprecationManager::on_level_setting_update(int64_t new_level) {
-  JfrDeprecatedEventWriterState::on_level_setting_update(new_level);
-}
-
 void JfrDeprecationManager::on_safepoint_clear() {
   assert(!_enqueue_klasses, "invariant");
   // We are now starting JFR, so begin enqueuing tagged klasses.
@@ -270,6 +282,23 @@ static void add_to_leakp_set(const JfrDeprecatedEdge* edge) {
 static DeprecatedEdgeList::NodePtr _pending_head = nullptr;
 static DeprecatedEdgeList::NodePtr _pending_tail = nullptr;
 
+inline DeprecatedEdgeList::NodePtr pending_head() {
+  return Atomic::load(&_pending_head);
+}
+
+// The test for a pending head can be read concurrently from a thread doing class unloading.
+inline static bool has_pending_head() {
+  return pending_head() != nullptr;
+}
+
+inline static bool no_pending_head() {
+  return !has_pending_head();
+}
+
+inline static void set_pending_head(DeprecatedEdgeList::NodePtr head) {
+  Atomic::store(&_pending_head, head);
+}
+
 class PendingListProcessor {
  private:
   JfrCheckpointWriter& _writer;
@@ -281,66 +310,57 @@ class PendingListProcessor {
     JfrDeprecatedStackTraceWriter::install_stacktrace_blob(edge, _writer, _jt);
     assert(edge->has_stacktrace(), "invariant");
     add_to_leakp_set(edge);
-    if (_pending_head == nullptr) {
-      _pending_head = edge;
+    if (no_pending_head()) {
+      set_pending_head(edge);
     }
     _pending_tail = edge;
     return true;
   }
 };
 
-void JfrDeprecationManager::prepare_type_set(JavaThread* jt) {
-  _pending_head = nullptr;
+// Resets the pending head and tail.
+// Resets blob write states for nodes on the resolved list, dirtied in the previous epoch.
+static void reset_type_set_blobs() {
+  set_pending_head(nullptr);
   _pending_tail = nullptr;
+  if (_resolved_list.is_nonempty()) {
+    JfrDeprecatedEventClear clear;
+    _resolved_list.iterate(clear);
+  }
+}
+
+void JfrDeprecationManager::prepare_type_set(JavaThread* jt) {
+  reset_type_set_blobs();
   if (_pending_list.is_nonempty()) {
     JfrKlassUnloading::sort(true);
     JfrCheckpointWriter writer(true /* prev epoch */, jt,  false /* header */);
     PendingListProcessor plp(writer, jt);
     _pending_list.iterate(plp);
-    assert(_pending_head != nullptr, "invariant");
+    assert(has_pending_head(), "invariant");
     assert(_pending_tail != nullptr, "invariant");
     assert(_pending_tail->next() == nullptr, "invariant");
     // Excise already resolved edges to link them.
     _pending_tail->set_next(_resolved_list.cut());
     // Re-insertion.
-    _resolved_list.add_list(_pending_head);
+    _resolved_list.add_list(pending_head());
     _pending_list.clear();
   }
   assert(_pending_list.is_empty(), "invariant");
 }
 
-// A linked-list of blob handles.
-static JfrBlobHandle type_set_blobs;
-
-static inline void write_type_set_blobs(JfrCheckpointWriter& writer) {
-  type_set_blobs->write(writer);
-}
-
-static void save_type_set_blob(JfrCheckpointWriter& writer, bool copy = false) {
-  assert(writer.has_data(), "invariant");
-  const JfrBlobHandle blob = copy ? writer.copy() : writer.move();
-  if (type_set_blobs.valid()) {
-    type_set_blobs->set_next(blob);
-  } else {
-    type_set_blobs = blob;
-  }
-}
-
-void JfrDeprecationManager::on_type_set_unload(JfrCheckpointWriter& writer) {
-  if (writer.has_data()) {
-    save_type_set_blob(writer, true);
-  }
+bool JfrDeprecationManager::has_unresolved_entry() {
+  return _list.is_nonempty() || has_pending_head() || _pending_list.is_nonempty();
 }
 
 static inline bool has_stacktrace() {
   return JfrEventSetting::has_stacktrace(JfrDeprecatedInvocationEvent);
 }
 
-static inline bool write_events(JfrChunkWriter& cw) {
+static inline void write_events(JfrChunkWriter& cw, Thread* thread, bool on_error) {
   assert(_resolved_list.is_nonempty(), "invariant");
-  JfrDeprecatedEventWriter ebw(cw, has_stacktrace());
+  JfrCheckpointWriter type_set_writer(!on_error, thread, false);
+  JfrDeprecatedEventWriter ebw(cw, type_set_writer, has_stacktrace());
   _resolved_list.iterate(ebw);
-  return ebw.did_write();
 }
 
 static inline void write_stacktraces(JfrChunkWriter& cw) {
@@ -349,34 +369,30 @@ static inline void write_stacktraces(JfrChunkWriter& cw) {
   _resolved_list.iterate(scw);
 }
 
-static inline void write_type_sets(Thread* thread, bool on_error) {
-  JfrCheckpointWriter writer(!on_error, thread, false);
-  write_type_set_blobs(writer);
-}
-
-// First, we consolidate all stacktrace blobs into a single TYPE_STACKTRACE checkpoint and serialize it to the chunk.
-// Secondly, we serialize all events to the chunk.
-// Thirdly, the type set blobs are written into the JfrCheckpoint system, to be serialized to the chunk
-// just after we return from here.
+// First, we consolidate all stack trace blobs into a single TYPE_STACKTRACE checkpoint
+// and serialize it to the chunk. Then, all events are serialized, and unique type set blobs
+// written into the JfrCheckpoint system to be serialized to the chunk upon return.
 void JfrDeprecationManager::write_edges(JfrChunkWriter& cw, Thread* thread, bool on_error /* false */) {
   if (_resolved_list.is_nonempty() && JfrEventSetting::is_enabled(JfrDeprecatedInvocationEvent)) {
     if (has_stacktrace()) {
       write_stacktraces(cw);
     }
-    if (write_events(cw)) {
-      write_type_sets(thread, on_error);
-    }
+    write_events(cw, thread, on_error);
   }
 }
 
-void JfrDeprecationManager::on_type_set(JfrCheckpointWriter& writer, JfrChunkWriter* cw, Thread* thread) {
+void JfrDeprecationManager::on_type_set(JfrChunkWriter* cw, Thread* thread) {
   assert(_pending_list.is_empty(), "invariant");
-  if (_pending_head != nullptr) {
-    save_type_set_blob(writer);
-  } else {
-    writer.cancel();
+  if (has_pending_head()) {
+    assert(_pending_tail != nullptr, "invariant");
+    // Install type set blobs for the pending, i.e. unresolved nodes.
+    JfrReferenceCountedStorage::install(pending_head(), _pending_tail->next());
   }
   if (cw != nullptr) {
     write_edges(*cw, thread);
   }
 }
+
+void JfrDeprecationManager::on_level_setting_update(int64_t new_level) {
+  JfrDeprecatedEventWriterState::on_level_setting_update(new_level);
+}

src/hotspot/share/jfr/support/jfrDeprecationManager.hpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2023, 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
@@ -42,6 +42,7 @@ class JfrDeprecatedEdge : public CHeapObj<mtTracing> {
  private:
   JfrTicks _invocation_time;
   JfrBlobHandle _stacktrace;
+  JfrBlobHandle _type_set;
   JfrDeprecatedEdge* _next;
   InstanceKlass* _deprecated_ik;
   traceid _deprecated_methodid;
@@ -58,7 +59,7 @@ class JfrDeprecatedEdge : public CHeapObj<mtTracing> {
  public:
   JfrDeprecatedEdge(const Method* method, Method* sender, int bci, u1 frame_type, JavaThread* jt);
 
-  const JfrDeprecatedEdge* next() const { return _next; }
+  JfrDeprecatedEdge* next() const { return _next; }
   void set_next(JfrDeprecatedEdge* edge) { _next = edge; }
 
   bool has_event() const;
@@ -68,6 +69,10 @@ class JfrDeprecatedEdge : public CHeapObj<mtTracing> {
   const JfrBlobHandle& stacktrace() const;
   void install_stacktrace_blob(JavaThread* jt);
 
+  bool has_type_set() const;
+  const JfrBlobHandle& type_set() const;
+  void install_type_set(const JfrBlobHandle& type_set);
+
   const InstanceKlass* deprecated_ik() const { return _deprecated_ik; }
   traceid deprecated_methodid() const { return _deprecated_methodid; }
 
@@ -89,11 +94,11 @@ class JfrDeprecationManager : AllStatic {
   static void on_safepoint_write();
   static void on_recorder_stop();
   static void prepare_type_set(JavaThread* jt);
-  static void on_type_set(JfrCheckpointWriter& writer, JfrChunkWriter* cw, Thread* thread);
-  static void on_type_set_unload(JfrCheckpointWriter& writer);
+  static void on_type_set(JfrChunkWriter* cw, Thread* thread);
   static void write_edges(JfrChunkWriter& cw, Thread* thread, bool on_error = false);
   static void on_link(const Method* method, Method* sender, int bci, u1 frame_type, JavaThread* thread);
   static void on_level_setting_update(int64_t new_level);
+  static bool has_unresolved_entry();
 };
 
 #endif // SHARE_JFR_SUPPORT_JFRDEPRECATIONMANAGER_HPP

src/hotspot/share/jfr/support/jfrIntrinsics.hpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+* Copyright (c) 2012, 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
@@ -47,13 +47,13 @@ class JfrIntrinsicSupport : AllStatic {
 #define JFR_HAVE_INTRINSICS
 
 #define JFR_TEMPLATES(template)                                                                                      \
+  template(jdk_jfr_internal_HiddenWait,                               "jdk/jfr/internal/HiddenWait")                 \
   template(jdk_jfr_internal_JVM,                                      "jdk/jfr/internal/JVM")                        \
   template(jdk_jfr_internal_event_EventWriterFactory,                 "jdk/jfr/internal/event/EventWriterFactory")   \
   template(jdk_jfr_internal_event_EventConfiguration_signature,       "Ljdk/jfr/internal/event/EventConfiguration;") \
   template(getEventWriter_signature,                                  "()Ljdk/jfr/internal/event/EventWriter;")      \
   template(eventConfiguration_name,                                   "eventConfiguration")                          \
   template(commit_name,                                               "commit")                                      \
-  template(jfr_chunk_rotation_monitor,                                "jdk/jfr/internal/JVM$ChunkRotationMonitor")   \
 
 #define JFR_INTRINSICS(do_intrinsic, do_class, do_name, do_signature, do_alias)                                      \
   do_intrinsic(_counterTime,        jdk_jfr_internal_JVM, counterTime_name, void_long_signature, F_SN)               \

src/hotspot/share/jfr/support/jfrTraceIdExtension.hpp

@@ -44,11 +44,13 @@
 #define REMOVE_METHOD_ID(method) JfrTraceId::remove(method);
 #define RESTORE_ID(k) JfrTraceId::restore(k);
 
+static constexpr const uint16_t cleared_epoch_bits = 512 | 256;
+
 class JfrTraceFlag {
  private:
   mutable uint16_t _flags;
  public:
-  JfrTraceFlag() : _flags(0) {}
+  JfrTraceFlag() : _flags(cleared_epoch_bits) {}
   bool is_set(uint16_t flag) const {
     return (_flags & flag) != 0;
   }
@@ -96,9 +98,8 @@ class JfrTraceFlag {
   uint8_t* trace_meta_addr() const {               \
     return _trace_flags.meta_addr();               \
   }                                                \
-  void copy_trace_flags(uint8_t src_flags) const { \
-    uint8_t flags = *_trace_flags.flags_addr();    \
-    _trace_flags.set_flags(flags | src_flags);     \
+  void copy_trace_flags(uint16_t rhs_flags) const { \
+    _trace_flags.set_flags(_trace_flags.flags() | rhs_flags); \
   }
 
 #endif // SHARE_JFR_SUPPORT_JFRTRACEIDEXTENSION_HPP

src/hotspot/share/oops/cpCache.cpp

@@ -55,6 +55,7 @@
 #include "runtime/atomic.hpp"
 #include "runtime/handles.inline.hpp"
 #include "runtime/mutexLocker.hpp"
+#include "runtime/synchronizer.hpp"
 #include "runtime/vm_version.hpp"
 #include "utilities/macros.hpp"
 
@@ -173,7 +174,7 @@ void ConstantPoolCache::set_direct_or_vtable_call(Bytecodes::Code invoke_code,
     }
     if (invoke_code == Bytecodes::_invokestatic) {
       assert(method->method_holder()->is_initialized() ||
-             method->method_holder()->is_init_thread(JavaThread::current()),
+             method->method_holder()->is_reentrant_initialization(JavaThread::current()),
              "invalid class initialization state for invoke_static");
 
       if (!VM_Version::supports_fast_class_init_checks() && method->needs_clinit_barrier()) {
@@ -268,11 +269,20 @@ ResolvedMethodEntry* ConstantPoolCache::set_method_handle(int method_index, cons
   // A losing writer waits on the lock until the winner writes the method and leaves
   // the lock, so that when the losing writer returns, he can use the linked
   // cache entry.
+
   // Lock fields to write
   Bytecodes::Code invoke_code = Bytecodes::_invokehandle;
-  MutexLocker ml(constant_pool()->pool_holder()->init_monitor());
-  ResolvedMethodEntry* method_entry = resolved_method_entry_at(method_index);
 
+  JavaThread* current = JavaThread::current();
+  objArrayHandle resolved_references(current, constant_pool()->resolved_references());
+  // Use the resolved_references() lock for this cpCache entry.
+  // resolved_references are created for all classes with Invokedynamic, MethodHandle
+  // or MethodType constant pool cache entries.
+  assert(resolved_references() != nullptr,
+         "a resolved_references array should have been created for this class");
+  ObjectLocker ol(resolved_references, current);
+
+  ResolvedMethodEntry* method_entry = resolved_method_entry_at(method_index);
   if (method_entry->is_resolved(invoke_code)) {
     return method_entry;
   }
@@ -310,7 +320,6 @@ ResolvedMethodEntry* ConstantPoolCache::set_method_handle(int method_index, cons
   // Store appendix, if any.
   if (has_appendix) {
     const int appendix_index = method_entry->resolved_references_index();
-    objArrayOop resolved_references = constant_pool()->resolved_references();
     assert(appendix_index >= 0 && appendix_index < resolved_references->length(), "oob");
     assert(resolved_references->obj_at(appendix_index) == nullptr, "init just once");
     resolved_references->obj_at_put(appendix_index, appendix());
@@ -555,7 +564,14 @@ bool ConstantPoolCache::save_and_throw_indy_exc(
   assert(PENDING_EXCEPTION->is_a(vmClasses::LinkageError_klass()),
          "No LinkageError exception");
 
-  MutexLocker ml(THREAD, cpool->pool_holder()->init_monitor());
+  // Use the resolved_references() lock for this cpCache entry.
+  // resolved_references are created for all classes with Invokedynamic, MethodHandle
+  // or MethodType constant pool cache entries.
+  JavaThread* current = THREAD;
+  objArrayHandle resolved_references(current, cpool->resolved_references());
+  assert(resolved_references() != nullptr,
+         "a resolved_references array should have been created for this class");
+  ObjectLocker ol(resolved_references, current);
 
   // if the indy_info is resolved or the indy_resolution_failed flag is set then another
   // thread either succeeded in resolving the method or got a LinkageError
@@ -578,11 +594,21 @@ bool ConstantPoolCache::save_and_throw_indy_exc(
 
 oop ConstantPoolCache::set_dynamic_call(const CallInfo &call_info, int index) {
   ResourceMark rm;
-  MutexLocker ml(constant_pool()->pool_holder()->init_monitor());
+
+  // Use the resolved_references() lock for this cpCache entry.
+  // resolved_references are created for all classes with Invokedynamic, MethodHandle
+  // or MethodType constant pool cache entries.
+  JavaThread* current = JavaThread::current();
+  constantPoolHandle cp(current, constant_pool());
+
+  objArrayHandle resolved_references(current, cp->resolved_references());
+  assert(resolved_references() != nullptr,
+         "a resolved_references array should have been created for this class");
+  ObjectLocker ol(resolved_references, current);
   assert(index >= 0, "Indy index must be positive at this point");
 
   if (resolved_indy_entry_at(index)->method() != nullptr) {
-    return constant_pool()->resolved_reference_from_indy(index);
+    return cp->resolved_reference_from_indy(index);
   }
 
   if (resolved_indy_entry_at(index)->resolution_failed()) {
@@ -590,9 +616,7 @@ oop ConstantPoolCache::set_dynamic_call(const CallInfo &call_info, int index) {
     // resolution.  Ignore our success and throw their exception.
     guarantee(index >= 0, "Invalid indy index");
     int encoded_index = ResolutionErrorTable::encode_indy_index(index);
-    JavaThread* THREAD = JavaThread::current(); // For exception macros.
-    constantPoolHandle cp(THREAD, constant_pool());
-    ConstantPool::throw_resolution_error(cp, encoded_index, THREAD);
+    ConstantPool::throw_resolution_error(cp, encoded_index, current);
     return nullptr;
   }
 
@@ -616,7 +640,6 @@ oop ConstantPoolCache::set_dynamic_call(const CallInfo &call_info, int index) {
 
   if (has_appendix) {
     const int appendix_index = resolved_indy_entry_at(index)->resolved_references_index();
-    objArrayOop resolved_references = constant_pool()->resolved_references();
     assert(appendix_index >= 0 && appendix_index < resolved_references->length(), "oob");
     assert(resolved_references->obj_at(appendix_index) == nullptr, "init just once");
     resolved_references->obj_at_put(appendix_index, appendix());

src/hotspot/share/oops/instanceKlass.cpp

@@ -86,6 +86,7 @@
 #include "runtime/orderAccess.hpp"
 #include "runtime/os.inline.hpp"
 #include "runtime/reflection.hpp"
+#include "runtime/synchronizer.hpp"
 #include "runtime/threads.hpp"
 #include "services/classLoadingService.hpp"
 #include "services/finalizerService.hpp"
@@ -497,9 +498,6 @@ Array<int>* InstanceKlass::create_new_default_vtable_indices(int len, TRAPS) {
   return vtable_indices;
 }
 
-static Monitor* create_init_monitor(const char* name) {
-  return new Monitor(Mutex::safepoint, name);
-}
 
 InstanceKlass::InstanceKlass() {
   assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for CDS");
@@ -517,7 +515,6 @@ InstanceKlass::InstanceKlass(const ClassFileParser& parser, KlassKind kind, Refe
   _nest_host_index(0),
   _init_state(allocated),
   _reference_type(reference_type),
-  _init_monitor(create_init_monitor("InstanceKlassInitMonitor_lock")),
   _init_thread(nullptr)
 {
   set_vtable_length(parser.vtable_size());
@@ -745,6 +742,28 @@ objArrayOop InstanceKlass::signers() const {
   return java_lang_Class::signers(java_mirror());
 }
 
+oop InstanceKlass::init_lock() const {
+  // return the init lock from the mirror
+  oop lock = java_lang_Class::init_lock(java_mirror());
+  // Prevent reordering with any access of initialization state
+  OrderAccess::loadload();
+  assert(lock != nullptr || !is_not_initialized(), // initialized or in_error state
+         "only fully initialized state can have a null lock");
+  return lock;
+}
+
+// Set the initialization lock to null so the object can be GC'ed.  Any racing
+// threads to get this lock will see a null lock and will not lock.
+// That's okay because they all check for initialized state after getting
+// the lock and return.
+void InstanceKlass::fence_and_clear_init_lock() {
+  // make sure previous stores are all done, notably the init_state.
+  OrderAccess::storestore();
+  java_lang_Class::clear_init_lock(java_mirror());
+  assert(!is_not_initialized(), "class must be initialized now");
+}
+
+
 // See "The Virtual Machine Specification" section 2.16.5 for a detailed explanation of the class initialization
 // process. The step comments refers to the procedure described in that section.
 // Note: implementation moved to static method to expose the this pointer.
@@ -772,49 +791,6 @@ void InstanceKlass::link_class(TRAPS) {
   }
 }
 
-void InstanceKlass::check_link_state_and_wait(JavaThread* current) {
-  MonitorLocker ml(current, _init_monitor);
-
-  bool debug_logging_enabled = log_is_enabled(Debug, class, init);
-
-  // Another thread is linking this class, wait.
-  while (is_being_linked() && !is_init_thread(current)) {
-    if (debug_logging_enabled) {
-      ResourceMark rm(current);
-      log_debug(class, init)("Thread \"%s\" waiting for linking of %s by thread \"%s\"",
-                             current->name(), external_name(), init_thread_name());
-    }
-    ml.wait();
-  }
-
-  // This thread is recursively linking this class, continue
-  if (is_being_linked() && is_init_thread(current)) {
-    if (debug_logging_enabled) {
-      ResourceMark rm(current);
-      log_debug(class, init)("Thread \"%s\" recursively linking %s",
-                             current->name(), external_name());
-    }
-    return;
-  }
-
-  // If this class wasn't linked already, set state to being_linked
-  if (!is_linked()) {
-    if (debug_logging_enabled) {
-      ResourceMark rm(current);
-      log_debug(class, init)("Thread \"%s\" linking %s",
-                             current->name(), external_name());
-    }
-    set_init_state(being_linked);
-    set_init_thread(current);
-  } else {
-    if (debug_logging_enabled) {
-      ResourceMark rm(current);
-      log_debug(class, init)("Thread \"%s\" found %s already linked",
-                             current->name(), external_name());
-      }
-  }
-}
-
 // Called to verify that a class can link during initialization, without
 // throwing a VerifyError.
 bool InstanceKlass::link_class_or_fail(TRAPS) {
@@ -893,8 +869,9 @@ bool InstanceKlass::link_class_impl(TRAPS) {
 
   // verification & rewriting
   {
-    LockLinkState init_lock(this, jt);
-
+    HandleMark hm(THREAD);
+    Handle h_init_lock(THREAD, init_lock());
+    ObjectLocker ol(h_init_lock, jt);
     // rewritten will have been set if loader constraint error found
     // on an earlier link attempt
     // don't verify or rewrite if already rewritten
@@ -952,7 +929,21 @@ bool InstanceKlass::link_class_impl(TRAPS) {
       // In case itable verification is ever added.
       // itable().verify(tty, true);
 #endif
-      set_initialization_state_and_notify(linked, THREAD);
+      if (UseVtableBasedCHA && Universe::is_fully_initialized()) {
+        DeoptimizationScope deopt_scope;
+        {
+          // Now mark all code that assumes the class is not linked.
+          // Set state under the Compile_lock also.
+          MutexLocker ml(THREAD, Compile_lock);
+
+          set_init_state(linked);
+          CodeCache::mark_dependents_on(&deopt_scope, this);
+        }
+        // Perform the deopt handshake outside Compile_lock.
+        deopt_scope.deoptimize_marked();
+      } else {
+        set_init_state(linked);
+      }
       if (JvmtiExport::should_post_class_prepare()) {
         JvmtiExport::post_class_prepare(THREAD, this);
       }
@@ -1082,7 +1073,6 @@ void InstanceKlass::initialize_impl(TRAPS) {
   DTRACE_CLASSINIT_PROBE(required, -1);
 
   bool wait = false;
-  bool throw_error = false;
 
   JavaThread* jt = THREAD;
 
@@ -1091,24 +1081,27 @@ void InstanceKlass::initialize_impl(TRAPS) {
   // refer to the JVM book page 47 for description of steps
   // Step 1
   {
-    MonitorLocker ml(jt, _init_monitor);
+    Handle h_init_lock(THREAD, init_lock());
+    ObjectLocker ol(h_init_lock, jt);
 
     // Step 2
-    while (is_being_initialized() && !is_init_thread(jt)) {
+    // If we were to use wait() instead of waitInterruptibly() then
+    // we might end up throwing IE from link/symbol resolution sites
+    // that aren't expected to throw.  This would wreak havoc.  See 6320309.
+    while (is_being_initialized() && !is_reentrant_initialization(jt)) {
       if (debug_logging_enabled) {
         ResourceMark rm(jt);
         log_debug(class, init)("Thread \"%s\" waiting for initialization of %s by thread \"%s\"",
                                jt->name(), external_name(), init_thread_name());
       }
-
       wait = true;
       jt->set_class_to_be_initialized(this);
-      ml.wait();
+      ol.wait_uninterruptibly(jt);
       jt->set_class_to_be_initialized(nullptr);
     }
 
     // Step 3
-    if (is_being_initialized() && is_init_thread(jt)) {
+    if (is_being_initialized() && is_reentrant_initialization(jt)) {
       if (debug_logging_enabled) {
         ResourceMark rm(jt);
         log_debug(class, init)("Thread \"%s\" recursively initializing %s",
@@ -1136,7 +1129,19 @@ void InstanceKlass::initialize_impl(TRAPS) {
         log_debug(class, init)("Thread \"%s\" found %s is in error state",
                                jt->name(), external_name());
       }
-      throw_error = true;
+
+      DTRACE_CLASSINIT_PROBE_WAIT(erroneous, -1, wait);
+      ResourceMark rm(THREAD);
+      Handle cause(THREAD, get_initialization_error(THREAD));
+
+      stringStream ss;
+      ss.print("Could not initialize class %s", external_name());
+      if (cause.is_null()) {
+        THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), ss.as_string());
+      } else {
+        THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(),
+                        ss.as_string(), cause);
+      }
     } else {
 
       // Step 6
@@ -1150,22 +1155,6 @@ void InstanceKlass::initialize_impl(TRAPS) {
     }
   }
 
-  // Throw error outside lock
-  if (throw_error) {
-    DTRACE_CLASSINIT_PROBE_WAIT(erroneous, -1, wait);
-    ResourceMark rm(THREAD);
-    Handle cause(THREAD, get_initialization_error(THREAD));
-
-    stringStream ss;
-    ss.print("Could not initialize class %s", external_name());
-    if (cause.is_null()) {
-      THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), ss.as_string());
-    } else {
-      THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(),
-                      ss.as_string(), cause);
-    }
-  }
-
   // Step 7
   // Next, if C is a class rather than an interface, initialize it's super class and super
   // interfaces.
@@ -1223,7 +1212,7 @@ void InstanceKlass::initialize_impl(TRAPS) {
 
   // Step 9
   if (!HAS_PENDING_EXCEPTION) {
-    set_initialization_state_and_notify(fully_initialized, THREAD);
+    set_initialization_state_and_notify(fully_initialized, CHECK);
     debug_only(vtable().verify(tty, true);)
   }
   else {
@@ -1256,43 +1245,26 @@ void InstanceKlass::initialize_impl(TRAPS) {
 }
 
 
-void InstanceKlass::set_initialization_state_and_notify(ClassState state, JavaThread* current) {
-  MonitorLocker ml(current, _init_monitor);
-
-  if (state == linked && UseVtableBasedCHA && Universe::is_fully_initialized()) {
-    DeoptimizationScope deopt_scope;
-    {
-      // Now mark all code that assumes the class is not linked.
-      // Set state under the Compile_lock also.
-      MutexLocker ml(current, Compile_lock);
-
-      set_init_thread(nullptr); // reset _init_thread before changing _init_state
-      set_init_state(state);
-
-      CodeCache::mark_dependents_on(&deopt_scope, this);
-    }
-    // Perform the deopt handshake outside Compile_lock.
-    deopt_scope.deoptimize_marked();
+void InstanceKlass::set_initialization_state_and_notify(ClassState state, TRAPS) {
+  Handle h_init_lock(THREAD, init_lock());
+  if (h_init_lock() != nullptr) {
+    ObjectLocker ol(h_init_lock, THREAD);
+    set_init_thread(nullptr); // reset _init_thread before changing _init_state
+    set_init_state(state);
+    fence_and_clear_init_lock();
+    ol.notify_all(CHECK);
   } else {
+    assert(h_init_lock() != nullptr, "The initialization state should never be set twice");
     set_init_thread(nullptr); // reset _init_thread before changing _init_state
     set_init_state(state);
   }
-  ml.notify_all();
 }
 
 // Update hierarchy. This is done before the new klass has been added to the SystemDictionary. The Compile_lock
 // is grabbed, to ensure that the compiler is not using the class hierarchy.
-void InstanceKlass::add_to_hierarchy(JavaThread* current) {
+void InstanceKlass::add_to_hierarchy_impl(JavaThread* current) {
   assert(!SafepointSynchronize::is_at_safepoint(), "must NOT be at safepoint");
 
-  // In case we are not using CHA based vtables we need to make sure the loaded
-  // deopt is completed before anyone links this class.
-  // Linking is done with _init_monitor held, by loading and deopting with it
-  // held we make sure the deopt is completed before linking.
-  if (!UseVtableBasedCHA) {
-    init_monitor()->lock();
-  }
-
   DeoptimizationScope deopt_scope;
   {
     MutexLocker ml(current, Compile_lock);
@@ -1314,12 +1286,26 @@ void InstanceKlass::add_to_hierarchy(JavaThread* current) {
   }
   // Perform the deopt handshake outside Compile_lock.
   deopt_scope.deoptimize_marked();
+}
 
-  if (!UseVtableBasedCHA) {
-    init_monitor()->unlock();
+void InstanceKlass::add_to_hierarchy(JavaThread* current) {
+
+  if (UseVtableBasedCHA || !Universe::is_fully_initialized()) {
+    add_to_hierarchy_impl(current);
+  } else {
+    // In case we are not using CHA based vtables we need to make sure the loaded
+    // deopt is completed before anyone links this class.
+    // Linking is done with init_lock held, by loading and deopting with it
+    // held we make sure the deopt is completed before linking.
+    Handle h_init_lock(current, init_lock());
+    ObjectLocker ol(h_init_lock, current);
+    add_to_hierarchy_impl(current);
+
+    // This doesn't need a notify because the wait is only on the class initialization path.
   }
 }
 
+
 InstanceKlass* InstanceKlass::implementor() const {
   InstanceKlass* volatile* ik = adr_implementor();
   if (ik == nullptr) {
@@ -2586,7 +2572,6 @@ void InstanceKlass::remove_unshareable_info() {
   _nest_host = nullptr;
   init_shared_package_entry();
   _dep_context_last_cleaned = 0;
-  _init_monitor = nullptr;
 
   remove_unshareable_flags();
 }
@@ -2690,9 +2675,6 @@ void InstanceKlass::restore_unshareable_info(ClassLoaderData* loader_data, Handl
   if (DiagnoseSyncOnValueBasedClasses && has_value_based_class_annotation()) {
     set_is_value_based();
   }
-
-  // restore the monitor
-  _init_monitor = create_init_monitor("InstanceKlassInitMonitorRestored_lock");
 }
 
 // Check if a class or any of its supertypes has a version older than 50.
@@ -2788,9 +2770,6 @@ void InstanceKlass::release_C_heap_structures(bool release_sub_metadata) {
     methods_do(method_release_C_heap_structures);
   }
 
-  // Destroy the init_monitor
-  delete _init_monitor;
-
   // Deallocate oop map cache
   if (_oop_map_cache != nullptr) {
     delete _oop_map_cache;
@@ -3482,7 +3461,7 @@ nmethod* InstanceKlass::lookup_osr_nmethod(const Method* m, int bci, int comp_le
 #define BULLET  " - "
 
 static const char* state_names[] = {
-  "allocated", "loaded", "being_linked", "linked", "being_initialized", "fully_initialized", "initialization_error"
+  "allocated", "loaded", "linked", "being_initialized", "fully_initialized", "initialization_error"
 };
 
 static void print_vtable(intptr_t* start, int len, outputStream* st) {
@@ -4132,17 +4111,13 @@ void JNIid::verify(Klass* holder) {
 }
 
 void InstanceKlass::set_init_state(ClassState state) {
-  if (state > loaded) {
-    assert_lock_strong(_init_monitor);
-  }
 #ifdef ASSERT
   bool good_state = is_shared() ? (_init_state <= state)
                                                : (_init_state < state);
-  bool link_failed = _init_state == being_linked && state == loaded;
-  assert(good_state || state == allocated || link_failed, "illegal state transition");
+  assert(good_state || state == allocated, "illegal state transition");
 #endif
   assert(_init_thread == nullptr, "should be cleared before state change");
-  Atomic::store(&_init_state, state);
+  _init_state = state;
 }
 
 #if INCLUDE_JVMTI

src/hotspot/share/oops/instanceKlass.hpp

@@ -152,7 +152,6 @@ class InstanceKlass: public Klass {
   enum ClassState : u1 {
     allocated,                          // allocated (but not yet linked)
     loaded,                             // loaded and inserted in class hierarchy (but not linked yet)
-    being_linked,                       // currently running verifier and rewriter
     linked,                             // successfully linked/verified (but not initialized yet)
     being_initialized,                  // currently running class initializer
     fully_initialized,                  // initialized (successful final state)
@@ -226,14 +225,20 @@ class InstanceKlass: public Klass {
 
   volatile u2     _idnum_allocated_count;   // JNI/JVMTI: increments with the addition of methods, old ids don't change
 
+  // _is_marked_dependent can be set concurrently, thus cannot be part of the
+  // _misc_flags.
+  bool            _is_marked_dependent;     // used for marking during flushing and deoptimization
+
+  // Class states are defined as ClassState (see above).
+  // Place the _init_state here to utilize the unused 2-byte after
+  // _idnum_allocated_count.
   volatile ClassState _init_state;          // state of class
 
-  u1              _reference_type;          // reference type
+  u1              _reference_type;                // reference type
 
   // State is set either at parse time or while executing, atomically to not disturb other state
   InstanceKlassFlags _misc_flags;
 
-  Monitor*             _init_monitor;       // mutual exclusion to _init_state and _init_thread.
   JavaThread* volatile _init_thread;        // Pointer to current thread doing initialization (to handle recursive initialization)
 
   OopMapCache*    volatile _oop_map_cache;   // OopMapCache for all methods in the klass (allocated lazily)
@@ -497,41 +502,23 @@ public:
                                        TRAPS);
 
   JavaThread* init_thread()  { return Atomic::load(&_init_thread); }
-  // We can safely access the name as long as we hold the _init_monitor.
   const char* init_thread_name() {
-    assert(_init_monitor->owned_by_self(), "Must hold _init_monitor here");
     return init_thread()->name_raw();
   }
 
  public:
   // initialization state
-  bool is_loaded() const                   { return init_state() >= loaded; }
-  bool is_linked() const                   { return init_state() >= linked; }
-  bool is_being_linked() const             { return init_state() == being_linked; }
-  bool is_initialized() const              { return init_state() == fully_initialized; }
-  bool is_not_initialized() const          { return init_state() <  being_initialized; }
-  bool is_being_initialized() const        { return init_state() == being_initialized; }
-  bool is_in_error_state() const           { return init_state() == initialization_error; }
-  bool is_init_thread(JavaThread *thread)  { return thread == init_thread(); }
-  ClassState  init_state() const           { return Atomic::load(&_init_state); }
+  bool is_loaded() const                   { return _init_state >= loaded; }
+  bool is_linked() const                   { return _init_state >= linked; }
+  bool is_initialized() const              { return _init_state == fully_initialized; }
+  bool is_not_initialized() const          { return _init_state <  being_initialized; }
+  bool is_being_initialized() const        { return _init_state == being_initialized; }
+  bool is_in_error_state() const           { return _init_state == initialization_error; }
+  bool is_reentrant_initialization(Thread *thread)  { return thread == _init_thread; }
+  ClassState  init_state() const           { return _init_state; }
   const char* init_state_name() const;
   bool is_rewritten() const                { return _misc_flags.rewritten(); }
 
-  class LockLinkState : public StackObj {
-    InstanceKlass* _ik;
-    JavaThread*    _current;
-   public:
-    LockLinkState(InstanceKlass* ik, JavaThread* current) : _ik(ik), _current(current) {
-      ik->check_link_state_and_wait(current);
-    }
-    ~LockLinkState() {
-      if (!_ik->is_linked()) {
-        // Reset to loaded if linking failed.
-        _ik->set_initialization_state_and_notify(loaded, _current);
-      }
-    }
-  };
-
   // is this a sealed class
   bool is_sealed() const;
 
@@ -829,7 +816,7 @@ public:
 
   // initialization
   void call_class_initializer(TRAPS);
-  void set_initialization_state_and_notify(ClassState state, JavaThread* current);
+  void set_initialization_state_and_notify(ClassState state, TRAPS);
 
   // OopMapCache support
   OopMapCache* oop_map_cache()               { return _oop_map_cache; }
@@ -841,6 +828,10 @@ public:
   void set_jni_ids(JNIid* ids)                   { _jni_ids = ids; }
   JNIid* jni_id_for(int offset);
 
+ private:
+  void add_to_hierarchy_impl(JavaThread* current);
+
+ public:
   // maintenance of deoptimization dependencies
   inline DependencyContext dependencies();
   void mark_dependent_nmethods(DeoptimizationScope* deopt_scope, KlassDepChange& changes);
@@ -1055,7 +1046,7 @@ public:
  public:
   u2 idnum_allocated_count() const      { return _idnum_allocated_count; }
 
- private:
+private:
   // initialization state
   void set_init_state(ClassState state);
   void set_rewritten()                  { _misc_flags.set_rewritten(true); }
@@ -1072,6 +1063,12 @@ public:
   jmethodID update_jmethod_id(jmethodID* jmeths, Method* method, int idnum);
 
 public:
+  // Lock for (1) initialization; (2) access to the ConstantPool of this class.
+  // Must be one per class and it has to be a VM internal object so java code
+  // cannot lock it (like the mirror).
+  // It has to be an object not a Mutex because it's held through java calls.
+  oop init_lock() const;
+
   // Returns the array class for the n'th dimension
   virtual ArrayKlass* array_klass(int n, TRAPS);
   virtual ArrayKlass* array_klass_or_null(int n);
@@ -1081,10 +1078,9 @@ public:
   virtual ArrayKlass* array_klass_or_null();
 
   static void clean_initialization_error_table();
-
-  Monitor* init_monitor() const { return _init_monitor; }
 private:
-  void check_link_state_and_wait(JavaThread* current);
+  void fence_and_clear_init_lock();
+
   bool link_class_impl                           (TRAPS);
   bool verify_code                               (TRAPS);
   void initialize_impl                           (TRAPS);

src/hotspot/share/oops/symbol.cpp

@@ -54,6 +54,7 @@ uint32_t Symbol::pack_hash_and_refcount(short hash, int refcount) {
 }
 
 Symbol::Symbol(const u1* name, int length, int refcount) {
+  assert(length <= max_length(), "SymbolTable should have caught this!");
   _hash_and_refcount =  pack_hash_and_refcount((short)os::random(), refcount);
   _length = (u2)length;
   // _body[0..1] are allocated in the header just by coincidence in the current

src/hotspot/share/oops/symbol.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
@@ -130,6 +130,7 @@ class Symbol : public MetaspaceObj {
     return (int)heap_word_size(byte_size(length));
   }
 
+  // Constructor is private for use only by SymbolTable.
   Symbol(const u1* name, int length, int refcount);
 
   static short extract_hash(uint32_t value)   { return (short)(value >> 16); }

src/hotspot/share/opto/callnode.cpp

@@ -1950,6 +1950,22 @@ bool AbstractLockNode::find_unlocks_for_region(const RegionNode* region, LockNod
 
 }
 
+// Check that all locks/unlocks associated with object come from balanced regions.
+bool AbstractLockNode::is_balanced() {
+  Node* obj = obj_node();
+  for (uint j = 0; j < obj->outcnt(); j++) {
+    Node* n = obj->raw_out(j);
+    if (n->is_AbstractLock() &&
+        n->as_AbstractLock()->obj_node()->eqv_uncast(obj)) {
+      BoxLockNode* n_box = n->as_AbstractLock()->box_node()->as_BoxLock();
+      if (n_box->is_unbalanced()) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
 const char* AbstractLockNode::_kind_names[] = {"Regular", "NonEscObj", "Coarsened", "Nested"};
 
 const char * AbstractLockNode::kind_as_string() const {
@@ -2056,6 +2072,8 @@ Node *LockNode::Ideal(PhaseGVN *phase, bool can_reshape) {
           int unlocks = 0;
           if (Verbose) {
             tty->print_cr("=== Locks coarsening ===");
+            tty->print("Obj: ");
+            obj_node()->dump();
           }
           for (int i = 0; i < lock_ops.length(); i++) {
             AbstractLockNode* lock = lock_ops.at(i);
@@ -2064,6 +2082,8 @@ Node *LockNode::Ideal(PhaseGVN *phase, bool can_reshape) {
             else
               unlocks++;
             if (Verbose) {
+              tty->print("Box %d: ", i);
+              box_node()->dump();
               tty->print(" %d: ", i);
               lock->dump();
             }

src/hotspot/share/opto/callnode.hpp

@@ -1154,6 +1154,10 @@ public:
   void set_coarsened()   { _kind = Coarsened; set_eliminated_lock_counter(); }
   void set_nested()      { _kind = Nested; set_eliminated_lock_counter(); }
 
+  // Check that all locks/unlocks associated with object come from balanced regions.
+  // They can become unbalanced after coarsening optimization or on OSR entry.
+  bool is_balanced();
+
   // locking does not modify its arguments
   virtual bool may_modify(const TypeOopPtr* t_oop, PhaseValues* phase){ return false; }
 

src/hotspot/share/opto/escape.cpp

@@ -574,18 +574,23 @@ bool ConnectionGraph::can_reduce_check_users(Node* n, uint nesting) const {
         // CmpP/N used by the If controlling the cast.
         if (use->in(0)->is_IfTrue() || use->in(0)->is_IfFalse()) {
           Node* iff = use->in(0)->in(0);
-          if (iff->Opcode() == Op_If && iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp()) {
+          // We may have Opaque4 node between If and Bool nodes.
+          // Bail out in such case - we need to preserve Opaque4 for correct
+          // processing predicates after loop opts.
+          bool can_reduce = (iff->Opcode() == Op_If) && iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp();
+          if (can_reduce) {
             Node* iff_cmp = iff->in(1)->in(1);
             int opc = iff_cmp->Opcode();
-            if ((opc == Op_CmpP || opc == Op_CmpN) && !can_reduce_cmp(n, iff_cmp)) {
+            can_reduce = (opc == Op_CmpP || opc == Op_CmpN) && can_reduce_cmp(n, iff_cmp);
+          }
+          if (!can_reduce) {
 #ifndef PRODUCT
-              if (TraceReduceAllocationMerges) {
-                tty->print_cr("Can NOT reduce Phi %d on invocation %d. CastPP %d doesn't have simple control.", n->_idx, _invocation, use->_idx);
-                n->dump(5);
-              }
-#endif
-              return false;
+            if (TraceReduceAllocationMerges) {
+              tty->print_cr("Can NOT reduce Phi %d on invocation %d. CastPP %d doesn't have simple control.", n->_idx, _invocation, use->_idx);
+              n->dump(5);
             }
+#endif
+            return false;
           }
         }
       }
@@ -651,7 +656,12 @@ Node* ConnectionGraph::specialize_cmp(Node* base, Node* curr_ctrl) {
   if (curr_ctrl == nullptr || curr_ctrl->is_Region()) {
     con = _igvn->zerocon(t->basic_type());
   } else {
-    Node* curr_cmp = curr_ctrl->in(0)->in(1)->in(1); // true/false -> if -> bool -> cmp
+    // can_reduce_check_users() verified graph: true/false -> if -> bool -> cmp
+    assert(curr_ctrl->in(0)->Opcode() == Op_If, "unexpected node %s", curr_ctrl->in(0)->Name());
+    Node* bol = curr_ctrl->in(0)->in(1);
+    assert(bol->is_Bool(), "unexpected node %s", bol->Name());
+    Node* curr_cmp = bol->in(1);
+    assert(curr_cmp->Opcode() == Op_CmpP || curr_cmp->Opcode() == Op_CmpN, "unexpected node %s", curr_cmp->Name());
     con = curr_cmp->in(1)->is_Con() ? curr_cmp->in(1) : curr_cmp->in(2);
   }
 
@@ -3501,12 +3511,11 @@ bool ConnectionGraph::not_global_escape(Node *n) {
 // and locked code region (identified by BoxLockNode) is balanced:
 // all compiled code paths have corresponding Lock/Unlock pairs.
 bool ConnectionGraph::can_eliminate_lock(AbstractLockNode* alock) {
-  BoxLockNode* box = alock->box_node()->as_BoxLock();
-  if (!box->is_unbalanced() && not_global_escape(alock->obj_node())) {
+  if (alock->is_balanced() && not_global_escape(alock->obj_node())) {
     if (EliminateNestedLocks) {
       // We can mark whole locking region as Local only when only
       // one object is used for locking.
-      box->set_local();
+      alock->box_node()->as_BoxLock()->set_local();
     }
     return true;
   }

src/hotspot/share/opto/ifnode.cpp

@@ -755,6 +755,7 @@ bool IfNode::cmpi_folds(PhaseIterGVN* igvn, bool fold_ne) {
 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {
   return ctrl != nullptr &&
     ctrl->is_Proj() &&
+    ctrl->outcnt() == 1 && // No side-effects
     ctrl->in(0) != nullptr &&
     ctrl->in(0)->Opcode() == Op_If &&
     ctrl->in(0)->outcnt() == 2 &&
@@ -1328,7 +1329,7 @@ Node* IfNode::fold_compares(PhaseIterGVN* igvn) {
 
   if (cmpi_folds(igvn)) {
     Node* ctrl = in(0);
-    if (is_ctrl_folds(ctrl, igvn) && ctrl->outcnt() == 1) {
+    if (is_ctrl_folds(ctrl, igvn)) {
       // A integer comparison immediately dominated by another integer
       // comparison
       ProjNode* success = nullptr;

src/hotspot/share/opto/library_call.cpp

@@ -5463,42 +5463,72 @@ void LibraryCallKit::create_new_uncommon_trap(CallStaticJavaNode* uncommon_trap_
   uncommon_trap_call->set_req(0, top()); // not used anymore, kill it
 }
 
+// Common checks for array sorting intrinsics arguments.
+// Returns `true` if checks passed.
+bool LibraryCallKit::check_array_sort_arguments(Node* elementType, Node* obj, BasicType& bt) {
+  // check address of the class
+  if (elementType == nullptr || elementType->is_top()) {
+    return false;  // dead path
+  }
+  const TypeInstPtr* elem_klass = gvn().type(elementType)->isa_instptr();
+  if (elem_klass == nullptr) {
+    return false;  // dead path
+  }
+  // java_mirror_type() returns non-null for compile-time Class constants only
+  ciType* elem_type = elem_klass->java_mirror_type();
+  if (elem_type == nullptr) {
+    return false;
+  }
+  bt = elem_type->basic_type();
+  // Disable the intrinsic if the CPU does not support SIMD sort
+  if (!Matcher::supports_simd_sort(bt)) {
+    return false;
+  }
+  // check address of the array
+  if (obj == nullptr || obj->is_top()) {
+    return false;  // dead path
+  }
+  const TypeAryPtr* obj_t = _gvn.type(obj)->isa_aryptr();
+  if (obj_t == nullptr || obj_t->elem() == Type::BOTTOM) {
+    return false; // failed input validation
+  }
+  return true;
+}
+
 //------------------------------inline_array_partition-----------------------
 bool LibraryCallKit::inline_array_partition() {
+  address stubAddr = StubRoutines::select_array_partition_function();
+  if (stubAddr == nullptr) {
+    return false; // Intrinsic's stub is not implemented on this platform
+  }
+  assert(callee()->signature()->size() == 9, "arrayPartition has 8 parameters (one long)");
 
-  Node* elementType     = null_check(argument(0));
+  // no receiver because it is a static method
+  Node* elementType     = argument(0);
   Node* obj             = argument(1);
-  Node* offset          = argument(2);
+  Node* offset          = argument(2); // long
   Node* fromIndex       = argument(4);
   Node* toIndex         = argument(5);
   Node* indexPivot1     = argument(6);
   Node* indexPivot2     = argument(7);
+  // PartitionOperation:  argument(8) is ignored
 
   Node* pivotIndices = nullptr;
+  BasicType bt = T_ILLEGAL;
 
+  if (!check_array_sort_arguments(elementType, obj, bt)) {
+    return false;
+  }
+  null_check(obj);
+  // If obj is dead, only null-path is taken.
+  if (stopped()) {
+    return true;
+  }
   // Set the original stack and the reexecute bit for the interpreter to reexecute
   // the bytecode that invokes DualPivotQuicksort.partition() if deoptimization happens.
   { PreserveReexecuteState preexecs(this);
     jvms()->set_should_reexecute(true);
 
-    const TypeInstPtr* elem_klass = gvn().type(elementType)->isa_instptr();
-    ciType* elem_type = elem_klass->const_oop()->as_instance()->java_mirror_type();
-    BasicType bt = elem_type->basic_type();
-    // Disable the intrinsic if the CPU does not support SIMD sort
-    if (!Matcher::supports_simd_sort(bt)) {
-      return false;
-    }
-    address stubAddr = nullptr;
-    stubAddr = StubRoutines::select_array_partition_function();
-    // stub not loaded
-    if (stubAddr == nullptr) {
-      return false;
-    }
-    // get the address of the array
-    const TypeAryPtr* obj_t = _gvn.type(obj)->isa_aryptr();
-    if (obj_t == nullptr || obj_t->elem() == Type::BOTTOM ) {
-      return false; // failed input validation
-    }
     Node* obj_adr = make_unsafe_address(obj, offset);
 
     // create the pivotIndices array of type int and size = 2
@@ -5531,31 +5561,29 @@ bool LibraryCallKit::inline_array_partition() {
 
 //------------------------------inline_array_sort-----------------------
 bool LibraryCallKit::inline_array_sort() {
+  address stubAddr = StubRoutines::select_arraysort_function();
+  if (stubAddr == nullptr) {
+    return false; // Intrinsic's stub is not implemented on this platform
+  }
+  assert(callee()->signature()->size() == 7, "arraySort has 6 parameters (one long)");
 
-  Node* elementType     = null_check(argument(0));
+  // no receiver because it is a static method
+  Node* elementType     = argument(0);
   Node* obj             = argument(1);
-  Node* offset          = argument(2);
+  Node* offset          = argument(2); // long
   Node* fromIndex       = argument(4);
   Node* toIndex         = argument(5);
+  // SortOperation:       argument(6) is ignored
 
-  const TypeInstPtr* elem_klass = gvn().type(elementType)->isa_instptr();
-  ciType* elem_type = elem_klass->const_oop()->as_instance()->java_mirror_type();
-  BasicType bt = elem_type->basic_type();
-  // Disable the intrinsic if the CPU does not support SIMD sort
-  if (!Matcher::supports_simd_sort(bt)) {
+  BasicType bt = T_ILLEGAL;
+
+  if (!check_array_sort_arguments(elementType, obj, bt)) {
     return false;
   }
-  address stubAddr = nullptr;
-  stubAddr = StubRoutines::select_arraysort_function();
-  //stub not loaded
-  if (stubAddr == nullptr) {
-    return false;
-  }
-
-  // get address of the array
-  const TypeAryPtr* obj_t = _gvn.type(obj)->isa_aryptr();
-  if (obj_t == nullptr || obj_t->elem() == Type::BOTTOM ) {
-    return false; // failed input validation
+  null_check(obj);
+  // If obj is dead, only null-path is taken.
+  if (stopped()) {
+    return true;
   }
   Node* obj_adr = make_unsafe_address(obj, offset);
 
@@ -7554,8 +7582,6 @@ bool LibraryCallKit::inline_intpoly_montgomeryMult_P256() {
                                  OptoRuntime::intpoly_montgomeryMult_P256_Type(),
                                  stubAddr, stubName, TypePtr::BOTTOM,
                                  a_start, b_start, r_start);
-  Node* result = _gvn.transform(new ProjNode(call, TypeFunc::Parms));
-  set_result(result);
   return true;
 }
 

src/hotspot/share/opto/library_call.hpp

@@ -279,6 +279,7 @@ class LibraryCallKit : public GraphKit {
   JVMState* arraycopy_restore_alloc_state(AllocateArrayNode* alloc, int& saved_reexecute_sp);
   void arraycopy_move_allocation_here(AllocateArrayNode* alloc, Node* dest, JVMState* saved_jvms_before_guards, int saved_reexecute_sp,
                                       uint new_idx);
+  bool check_array_sort_arguments(Node* elementType, Node* obj, BasicType& bt);
   bool inline_array_sort();
   bool inline_array_partition();
   typedef enum { LS_get_add, LS_get_set, LS_cmp_swap, LS_cmp_swap_weak, LS_cmp_exchange } LoadStoreKind;

src/hotspot/share/opto/locknode.hpp

@@ -46,7 +46,7 @@ private:
     Eliminated         // All lock/unlock in region were eliminated
   } _kind;
 
-#ifdef ASSERT
+#ifndef PRODUCT
   const char* _kind_name[6] = {
    "Regular",
    "Local",
@@ -124,7 +124,9 @@ public:
 
 #ifndef PRODUCT
   virtual void format( PhaseRegAlloc *, outputStream *st ) const;
-  virtual void dump_spec(outputStream *st) const { st->print("  Lock %d",_slot); }
+  virtual void dump_spec(outputStream *st) const {
+    st->print("  Lock slot: %d, Kind: %s", _slot, _kind_name[(int)_kind]);
+  }
 #endif
 };
 

src/hotspot/share/opto/loopopts.cpp

@@ -795,18 +795,25 @@ Node *PhaseIdealLoop::conditional_move( Node *region ) {
   // Avoid duplicated float compare.
   if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
 
-  // Ignore cost if CMOVE can be moved outside the loop.
-  if (used_inside_loop && cost >= ConditionalMoveLimit) {
-    return nullptr;
+  float infrequent_prob = PROB_UNLIKELY_MAG(3);
+  // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
+  if (used_inside_loop) {
+    if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
+
+    // BlockLayoutByFrequency optimization moves infrequent branch
+    // from hot path. No point in CMOV'ing in such case (110 is used
+    // instead of 100 to take into account not exactness of float value).
+    if (BlockLayoutByFrequency) {
+      infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
+    }
   }
   // Check for highly predictable branch.  No point in CMOV'ing if
   // we are going to predict accurately all the time.
-  constexpr float infrequent_prob = PROB_UNLIKELY_MAG(2);
   if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
     //keep going
-  } else if (iff->_prob < infrequent_prob || iff->_prob > (1.0f - infrequent_prob)) {
+  } else if (iff->_prob < infrequent_prob ||
+      iff->_prob > (1.0f - infrequent_prob))
     return nullptr;
-  }
 
   // --------------
   // Now replace all Phis with CMOV's
@@ -2987,52 +2994,101 @@ RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
   return reg;
 }
 
-//------------------------------ insert_cmpi_loop_exit -------------------------------------
-// Clone a signed compare loop exit from an unsigned compare and
-// insert it before the unsigned cmp on the stay-in-loop path.
-// All new nodes inserted in the dominator tree between the original
-// if and it's projections.  The original if test is replaced with
-// a constant to force the stay-in-loop path.
+// Idea
+// ----
+// Partial Peeling tries to rotate the loop in such a way that it can later be turned into a counted loop. Counted loops
+// require a signed loop exit test. When calling this method, we've only found a suitable unsigned test to partial peel
+// with. Therefore, we try to split off a signed loop exit test from the unsigned test such that it can be used as new
+// loop exit while keeping the unsigned test unchanged and preserving the same behavior as if we've used the unsigned
+// test alone instead:
 //
-// This is done to make sure that the original if and it's projections
-// still dominate the same set of control nodes, that the ctrl() relation
-// from data nodes to them is preserved, and that their loop nesting is
-// preserved.
+// Before Partial Peeling:
+//   Loop:
+//     <peeled section>
+//     Split off signed loop exit test
+//     <-- CUT HERE -->
+//     Unchanged unsigned loop exit test
+//     <rest of unpeeled section>
+//     goto Loop
 //
-// before
-//          if(i <u limit)    unsigned compare loop exit
+// After Partial Peeling:
+//   <cloned peeled section>
+//   Cloned split off signed loop exit test
+//   Loop:
+//     Unchanged unsigned loop exit test
+//     <rest of unpeeled section>
+//     <peeled section>
+//     Split off signed loop exit test
+//     goto Loop
+//
+// Details
+// -------
+// Before:
+//          if (i <u limit)    Unsigned loop exit condition
 //         /       |
 //        v        v
 //   exit-proj   stay-in-loop-proj
 //
-// after
-//          if(stay-in-loop-const)  original if
-//         /       |
-//        /        v
-//       /  if(i <  limit)    new signed test
+// Split off a signed loop exit test (i.e. with CmpI) from an unsigned loop exit test (i.e. with CmpU) and insert it
+// before the CmpU on the stay-in-loop path and keep both tests:
+//
+//          if (i <u limit)    Signed loop exit test
+//        /        |
+//       /  if (i <u limit)    Unsigned loop exit test
 //      /  /       |
-//     /  /        v
-//    /  /  if(i <u limit)    new cloned unsigned test
-//   /  /   /      |
-//   v  v  v       |
-//    region       |
-//        |        |
-//      dum-if     |
-//     /  |        |
-// ether  |        |
-//        v        v
+//     v  v        v
+//  exit-region  stay-in-loop-proj
+//
+// Implementation
+// --------------
+// We need to make sure that the new signed loop exit test is properly inserted into the graph such that the unsigned
+// loop exit test still dominates the same set of control nodes, the ctrl() relation from data nodes to both loop
+// exit tests is preserved, and their loop nesting is correct.
+//
+// To achieve that, we clone the unsigned loop exit test completely (leave it unchanged), insert the signed loop exit
+// test above it and kill the original unsigned loop exit test by setting it's condition to a constant
+// (i.e. stay-in-loop-const in graph below) such that IGVN can fold it later:
+//
+//           if (stay-in-loop-const)  Killed original unsigned loop exit test
+//          /       |
+//         /        v
+//        /  if (i <  limit)          Split off signed loop exit test
+//       /  /       |
+//      /  /        v
+//     /  /  if (i <u limit)          Cloned unsigned loop exit test
+//    /  /   /      |
+//   v  v  v        |
+//  exit-region     |
+//        |         |
+//    dummy-if      |
+//     /  |         |
+// dead   |         |
+//        v         v
 //   exit-proj   stay-in-loop-proj
 //
-IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
+// Note: The dummy-if is inserted to create a region to merge the loop exits between the original to be killed unsigned
+//       loop exit test and its exit projection while keeping the exit projection (also see insert_region_before_proj()).
+//
+// Requirements
+// ------------
+// Note that we can only split off a signed loop exit test from the unsigned loop exit test when the behavior is exactly
+// the same as before with only a single unsigned test. This is only possible if certain requirements are met.
+// Otherwise, we need to bail out (see comments in the code below).
+IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree* loop) {
   const bool Signed   = true;
   const bool Unsigned = false;
 
   BoolNode* bol = if_cmpu->in(1)->as_Bool();
-  if (bol->_test._test != BoolTest::lt) return nullptr;
+  if (bol->_test._test != BoolTest::lt) {
+    return nullptr;
+  }
   CmpNode* cmpu = bol->in(1)->as_Cmp();
-  if (cmpu->Opcode() != Op_CmpU) return nullptr;
+  assert(cmpu->Opcode() == Op_CmpU, "must be unsigned comparison");
+
   int stride = stride_of_possible_iv(if_cmpu);
-  if (stride == 0) return nullptr;
+  if (stride == 0) {
+    return nullptr;
+  }
 
   Node* lp_proj = stay_in_loop(if_cmpu, loop);
   guarantee(lp_proj != nullptr, "null loop node");
@@ -3044,14 +3100,93 @@ IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *lo
     // We therefore can't add a single exit condition.
     return nullptr;
   }
-  // The loop exit condition is !(i <u limit) ==> (i < 0 || i >= limit).
-  // Split out the exit condition (i < 0) for stride < 0 or (i >= limit) for stride > 0.
-  Node* limit = nullptr;
+  // The unsigned loop exit condition is
+  //   !(i <u  limit)
+  // =   i >=u limit
+  //
+  // First, we note that for any x for which
+  //   0 <= x <= INT_MAX
+  // we can convert x to an unsigned int and still get the same guarantee:
+  //   0 <=  (uint) x <=  INT_MAX = (uint) INT_MAX
+  //   0 <=u (uint) x <=u INT_MAX = (uint) INT_MAX   (LEMMA)
+  //
+  // With that in mind, if
+  //   limit >= 0             (COND)
+  // then the unsigned loop exit condition
+  //   i >=u limit            (ULE)
+  // is equivalent to
+  //   i < 0 || i >= limit    (SLE-full)
+  // because either i is negative and therefore always greater than MAX_INT when converting to unsigned
+  //   (uint) i >=u MAX_INT >= limit >= 0
+  // or otherwise
+  //   i >= limit >= 0
+  // holds due to (LEMMA).
+  //
+  // For completeness, a counterexample with limit < 0:
+  // Assume i = -3 and limit = -2:
+  //   i  < 0
+  //   -2 < 0
+  // is true and thus also "i < 0 || i >= limit". But
+  //   i  >=u limit
+  //   -3 >=u -2
+  // is false.
+  Node* limit = cmpu->in(2);
+  const TypeInt* type_limit = _igvn.type(limit)->is_int();
+  if (type_limit->_lo < 0) {
+    return nullptr;
+  }
+
+  // We prove below that we can extract a single signed loop exit condition from (SLE-full), depending on the stride:
+  //   stride < 0:
+  //     i < 0        (SLE = SLE-negative)
+  //   stride > 0:
+  //     i >= limit   (SLE = SLE-positive)
+  // such that we have the following graph before Partial Peeling with stride > 0 (similar for stride < 0):
+  //
+  // Loop:
+  //   <peeled section>
+  //   i >= limit    (SLE-positive)
+  //   <-- CUT HERE -->
+  //   i >=u limit   (ULE)
+  //   <rest of unpeeled section>
+  //   goto Loop
+  //
+  // We exit the loop if:
+  //   (SLE) is true OR (ULE) is true
+  // However, if (SLE) is true then (ULE) also needs to be true to ensure the exact same behavior. Otherwise, we wrongly
+  // exit a loop that should not have been exited if we did not apply Partial Peeling. More formally, we need to ensure:
+  //   (SLE) IMPLIES (ULE)
+  // This indeed holds when (COND) is given:
+  // - stride > 0:
+  //       i >=  limit             // (SLE = SLE-positive)
+  //       i >=  limit >= 0        // (COND)
+  //       i >=u limit >= 0        // (LEMMA)
+  //     which is the unsigned loop exit condition (ULE).
+  // - stride < 0:
+  //       i        <  0           // (SLE = SLE-negative)
+  //       (uint) i >u MAX_INT     // (NEG) all negative values are greater than MAX_INT when converted to unsigned
+  //       MAX_INT >= limit >= 0   // (COND)
+  //       MAX_INT >=u limit >= 0  // (LEMMA)
+  //     and thus from (NEG) and (LEMMA):
+  //       i >=u limit
+  //     which is the unsigned loop exit condition (ULE).
+  //
+  //
+  // After Partial Peeling, we have the following structure for stride > 0 (similar for stride < 0):
+  //   <cloned peeled section>
+  //   i >= limit (SLE-positive)
+  //   Loop:
+  //     i >=u limit (ULE)
+  //     <rest of unpeeled section>
+  //     <peeled section>
+  //     i >= limit (SLE-positive)
+  //     goto Loop
+  Node* rhs_cmpi;
   if (stride > 0) {
-    limit = cmpu->in(2);
+    rhs_cmpi = limit; // For i >= limit
   } else {
-    limit = _igvn.makecon(TypeInt::ZERO);
-    set_ctrl(limit, C->root());
+    rhs_cmpi = _igvn.makecon(TypeInt::ZERO); // For i < 0
+    set_ctrl(rhs_cmpi, C->root());
   }
   // Create a new region on the exit path
   RegionNode* reg = insert_region_before_proj(lp_exit);
@@ -3059,7 +3194,7 @@ IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *lo
 
   // Clone the if-cmpu-true-false using a signed compare
   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
-  ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
+  ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, rhs_cmpi, lp_continue);
   reg->add_req(cmpi_exit);
 
   // Clone the if-cmpu-true-false

src/hotspot/share/opto/machnode.hpp

@@ -870,6 +870,10 @@ public:
     assert(verify_jvms(jvms), "jvms must match");
     return in(_jvmadj + jvms->monitor_box_offset(idx));
   }
+  Node* scalarized_obj(const JVMState* jvms, uint idx) const {
+    assert(verify_jvms(jvms), "jvms must match");
+    return in(_jvmadj + jvms->scloff() + idx);
+  }
   void  set_local(const JVMState* jvms, uint idx, Node *c) {
     assert(verify_jvms(jvms), "jvms must match");
     set_req(_jvmadj + jvms->locoff() + idx, c);

src/hotspot/share/opto/macro.cpp

@@ -2045,7 +2045,7 @@ void PhaseMacroExpand::mark_eliminated_box(Node* box, Node* obj) {
 
 //-----------------------mark_eliminated_locking_nodes-----------------------
 void PhaseMacroExpand::mark_eliminated_locking_nodes(AbstractLockNode *alock) {
-  if (alock->box_node()->as_BoxLock()->is_unbalanced()) {
+  if (!alock->is_balanced()) {
     return; // Can't do any more elimination for this locking region
   }
   if (EliminateNestedLocks) {

src/hotspot/share/opto/memnode.cpp

@@ -2984,6 +2984,9 @@ StoreNode* MergePrimitiveArrayStores::run() {
       type2aelembytes(bt) != _store->memory_size()) {
     return nullptr;
   }
+  if (_store->is_unsafe_access()) {
+    return nullptr;
+  }
 
   // The _store must be the "last" store in a chain. If we find a use we could merge with
   // then that use or a store further down is the "last" store.
@@ -3017,11 +3020,13 @@ bool MergePrimitiveArrayStores::is_compatible_store(const StoreNode* other_store
   int opc = _store->Opcode();
   assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
   assert(_store->adr_type()->isa_aryptr() != nullptr, "must be array store");
+  assert(!_store->is_unsafe_access(), "no unsafe accesses");
 
   if (other_store == nullptr ||
       _store->Opcode() != other_store->Opcode() ||
       other_store->adr_type() == nullptr ||
-      other_store->adr_type()->isa_aryptr() == nullptr) {
+      other_store->adr_type()->isa_aryptr() == nullptr ||
+      other_store->is_unsafe_access()) {
     return false;
   }
 

src/hotspot/share/opto/output.cpp

@@ -974,6 +974,27 @@ bool PhaseOutput::contains_as_owner(GrowableArray<MonitorValue*> *monarray, Obje
   return false;
 }
 
+// Determine if there is a scalar replaced object description represented by 'ov'.
+bool PhaseOutput::contains_as_scalarized_obj(JVMState* jvms, MachSafePointNode* sfn,
+                                             GrowableArray<ScopeValue*>* objs,
+                                             ObjectValue* ov) const {
+  for (int i = 0; i < jvms->scl_size(); i++) {
+    Node* n = sfn->scalarized_obj(jvms, i);
+    // Other kinds of nodes that we may encounter here, for instance constants
+    // representing values of fields of objects scalarized, aren't relevant for
+    // us, since they don't map to ObjectValue.
+    if (!n->is_SafePointScalarObject()) {
+      continue;
+    }
+
+    ObjectValue* other = (ObjectValue*) sv_for_node_id(objs, n->_idx);
+    if (ov == other) {
+      return true;
+    }
+  }
+  return false;
+}
+
 //--------------------------Process_OopMap_Node--------------------------------
 void PhaseOutput::Process_OopMap_Node(MachNode *mach, int current_offset) {
   // Handle special safepoint nodes for synchronization
@@ -1137,7 +1158,10 @@ void PhaseOutput::Process_OopMap_Node(MachNode *mach, int current_offset) {
 
         for (int j = 0; j< merge->possible_objects()->length(); j++) {
           ObjectValue* ov = merge->possible_objects()->at(j)->as_ObjectValue();
-          bool is_root = locarray->contains(ov) || exparray->contains(ov) || contains_as_owner(monarray, ov);
+          bool is_root = locarray->contains(ov) ||
+                         exparray->contains(ov) ||
+                         contains_as_owner(monarray, ov) ||
+                         contains_as_scalarized_obj(jvms, sfn, objs, ov);
           ov->set_root(is_root);
         }
       }

src/hotspot/share/opto/output.hpp

@@ -209,6 +209,9 @@ public:
 
   bool starts_bundle(const Node *n) const;
   bool contains_as_owner(GrowableArray<MonitorValue*> *monarray, ObjectValue *ov) const;
+  bool contains_as_scalarized_obj(JVMState* jvms, MachSafePointNode* sfn,
+                                  GrowableArray<ScopeValue*>* objs,
+                                  ObjectValue* ov) const;
 
   // Dump formatted assembly
 #if defined(SUPPORT_OPTO_ASSEMBLY)

src/hotspot/share/opto/runtime.cpp

@@ -1414,8 +1414,8 @@ const TypeFunc* OptoRuntime::intpoly_montgomeryMult_P256_Type() {
 
   // result type needed
   fields = TypeTuple::fields(1);
-  fields[TypeFunc::Parms + 0] = TypeInt::INT; // carry bits in output
-  const TypeTuple* range = TypeTuple::make(TypeFunc::Parms+1, fields);
+  fields[TypeFunc::Parms + 0] = nullptr; // void
+  const TypeTuple* range = TypeTuple::make(TypeFunc::Parms, fields);
   return TypeFunc::make(domain, range);
 }
 
@@ -1434,7 +1434,7 @@ const TypeFunc* OptoRuntime::intpoly_assign_Type() {
 
   // result type needed
   fields = TypeTuple::fields(1);
-  fields[TypeFunc::Parms + 0] = NULL; // void
+  fields[TypeFunc::Parms + 0] = nullptr; // void
   const TypeTuple* range = TypeTuple::make(TypeFunc::Parms, fields);
   return TypeFunc::make(domain, range);
 }

src/hotspot/share/opto/superword.cpp

@@ -3717,27 +3717,55 @@ void SuperWord::adjust_pre_loop_limit_to_align_main_loop_vectors() {
   TRACE_ALIGN_VECTOR_NODE(mask_AW);
   TRACE_ALIGN_VECTOR_NODE(adjust_pre_iter);
 
-  // 4: Compute (3a, b):
+  // 4: The computation of the new pre-loop limit could overflow (for 3a) or
+  //    underflow (for 3b) the int range. This is problematic in combination
+  //    with Range Check Elimination (RCE), which determines a "safe" range
+  //    where a RangeCheck will always succeed. RCE adjusts the pre-loop limit
+  //    such that we only enter the main-loop once we have reached the "safe"
+  //    range, and adjusts the main-loop limit so that we exit the main-loop
+  //    before we leave the "safe" range. After RCE, the range of the main-loop
+  //    can only be safely narrowed, and should never be widened. Hence, the
+  //    pre-loop limit can only be increased (for stride > 0), but an add
+  //    overflow might decrease it, or decreased (for stride < 0), but a sub
+  //    underflow might increase it. To prevent that, we perform the Sub / Add
+  //    and Max / Min with long operations.
+  old_limit       = new ConvI2LNode(old_limit);
+  orig_limit      = new ConvI2LNode(orig_limit);
+  adjust_pre_iter = new ConvI2LNode(adjust_pre_iter);
+  phase()->register_new_node(old_limit, pre_ctrl);
+  phase()->register_new_node(orig_limit, pre_ctrl);
+  phase()->register_new_node(adjust_pre_iter, pre_ctrl);
+  TRACE_ALIGN_VECTOR_NODE(old_limit);
+  TRACE_ALIGN_VECTOR_NODE(orig_limit);
+  TRACE_ALIGN_VECTOR_NODE(adjust_pre_iter);
+
+  // 5: Compute (3a, b):
   //    new_limit = old_limit + adjust_pre_iter     (stride > 0)
   //    new_limit = old_limit - adjust_pre_iter     (stride < 0)
+  //
   Node* new_limit = nullptr;
   if (stride < 0) {
-    new_limit = new SubINode(old_limit, adjust_pre_iter);
+    new_limit = new SubLNode(old_limit, adjust_pre_iter);
   } else {
-    new_limit = new AddINode(old_limit, adjust_pre_iter);
+    new_limit = new AddLNode(old_limit, adjust_pre_iter);
   }
   phase()->register_new_node(new_limit, pre_ctrl);
   TRACE_ALIGN_VECTOR_NODE(new_limit);
 
-  // 5: Compute (15a, b):
+  // 6: Compute (15a, b):
   //    Prevent pre-loop from going past the original limit of the loop.
   Node* constrained_limit =
-    (stride > 0) ? (Node*) new MinINode(new_limit, orig_limit)
-                 : (Node*) new MaxINode(new_limit, orig_limit);
+    (stride > 0) ? (Node*) new MinLNode(phase()->C, new_limit, orig_limit)
+                 : (Node*) new MaxLNode(phase()->C, new_limit, orig_limit);
   phase()->register_new_node(constrained_limit, pre_ctrl);
   TRACE_ALIGN_VECTOR_NODE(constrained_limit);
 
-  // 6: Hack the pre-loop limit
+  // 7: We know that the result is in the int range, there is never truncation
+  constrained_limit = new ConvL2INode(constrained_limit);
+  phase()->register_new_node(constrained_limit, pre_ctrl);
+  TRACE_ALIGN_VECTOR_NODE(constrained_limit);
+
+  // 8: Hack the pre-loop limit
   igvn().replace_input_of(pre_opaq, 1, constrained_limit);
 }
 

src/hotspot/share/prims/jvmtiEnvBase.cpp

@@ -2339,7 +2339,7 @@ JvmtiModuleClosure::get_all_modules(JvmtiEnv* env, jint* module_count_ptr, jobje
   }
 
   // Iterate over all the modules loaded to the system.
-  ClassLoaderDataGraph::modules_do(&do_module);
+  ClassLoaderDataGraph::modules_do_keepalive(&do_module);
 
   jint len = _tbl->length();
   guarantee(len > 0, "at least one module must be present");

src/hotspot/share/prims/jvmtiGetLoadedClasses.cpp

@@ -105,7 +105,7 @@ JvmtiGetLoadedClasses::getLoadedClasses(JvmtiEnv *env, jint* classCountPtr, jcla
     // Iterate through all classes in ClassLoaderDataGraph
     // and collect them using the LoadedClassesClosure
     MutexLocker mcld(ClassLoaderDataGraph_lock);
-    ClassLoaderDataGraph::loaded_classes_do(&closure);
+    ClassLoaderDataGraph::loaded_classes_do_keepalive(&closure);
   }
 
   return closure.get_result(env, classCountPtr, classesPtr);

src/hotspot/share/prims/jvmtiRedefineClasses.cpp

@@ -1174,7 +1174,7 @@ jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
           }
         }
       }
-      JFR_ONLY(k_new_method->copy_trace_flags(*k_old_method->trace_flags_addr());)
+      JFR_ONLY(k_new_method->copy_trace_flags(k_old_method->trace_flags());)
       log_trace(redefine, class, normalize)
         ("Method matched: new: %s [%d] == old: %s [%d]",
          k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);

src/hotspot/share/runtime/frame.cpp

@@ -947,7 +947,6 @@ void frame::oops_interpreted_do(OopClosure* f, const RegisterMap* map, bool quer
   InterpreterFrameClosure blk(this, max_locals, m->max_stack(), f);
 
   // process locals & expression stack
-  ResourceMark rm(thread);
   InterpreterOopMap mask;
   if (query_oop_map_cache) {
     m->mask_for(m, bci, &mask);

src/hotspot/share/runtime/objectMonitor.cpp

@@ -1442,7 +1442,7 @@ bool ObjectMonitor::check_owner(TRAPS) {
 static inline bool is_excluded(const Klass* monitor_klass) {
   assert(monitor_klass != nullptr, "invariant");
   NOT_JFR_RETURN_(false);
-  JFR_ONLY(return vmSymbols::jfr_chunk_rotation_monitor() == monitor_klass->name();)
+  JFR_ONLY(return vmSymbols::jdk_jfr_internal_HiddenWait() == monitor_klass->name();)
 }
 
 static void post_monitor_wait_event(EventJavaMonitorWait* event,

src/hotspot/share/runtime/sharedRuntime.cpp

@@ -1333,7 +1333,7 @@ methodHandle SharedRuntime::resolve_helper(bool is_virtual, bool is_optimized, T
 
   if (invoke_code == Bytecodes::_invokestatic) {
     assert(callee_method->method_holder()->is_initialized() ||
-           callee_method->method_holder()->is_init_thread(current),
+           callee_method->method_holder()->is_reentrant_initialization(current),
            "invalid class initialization state for invoke_static");
     if (!VM_Version::supports_fast_class_init_checks() && callee_method->needs_clinit_barrier()) {
       // In order to keep class initialization check, do not patch call

src/hotspot/share/runtime/synchronizer.cpp

@@ -821,6 +821,16 @@ int ObjectSynchronizer::wait(Handle obj, jlong millis, TRAPS) {
   return ret_code;
 }
 
+void ObjectSynchronizer::waitUninterruptibly(Handle obj, jlong millis, TRAPS) {
+  if (millis < 0) {
+    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "timeout value is negative");
+  }
+  ObjectSynchronizer::inflate(THREAD,
+                              obj(),
+                              inflate_cause_wait)->wait(millis, false, THREAD);
+}
+
+
 void ObjectSynchronizer::notify(Handle obj, TRAPS) {
   JavaThread* current = THREAD;
 

src/hotspot/share/runtime/synchronizer.hpp

@@ -119,6 +119,11 @@ public:
   static bool quick_notify(oopDesc* obj, JavaThread* current, bool All);
   static bool quick_enter(oop obj, JavaThread* current, BasicLock* Lock);
 
+  // Special internal-use-only method for use by JVM infrastructure
+  // that needs to wait() on a java-level object but that can't risk
+  // throwing unexpected InterruptedExecutionExceptions.
+  static void waitUninterruptibly(Handle obj, jlong Millis, TRAPS);
+
   // Inflate light weight monitor to heavy weight monitor
   static ObjectMonitor* inflate(Thread* current, oop obj, const InflateCause cause);
   // Used to inflate a monitor as if it was done from the thread JavaThread.
@@ -225,6 +230,7 @@ class ObjectLocker : public StackObj {
 
   // Monitor behavior
   void wait(TRAPS)  { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
+  void wait_uninterruptibly(TRAPS)  { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); } // wait forever
   void notify_all(TRAPS)  { ObjectSynchronizer::notifyall(_obj, CHECK); }
 };
 

src/hotspot/share/runtime/vframe.cpp

@@ -205,8 +205,9 @@ void javaVFrame::print_lock_info_on(outputStream* st, int frame_count) {
       Klass* k = obj->klass();
       st->print_cr("\t- %s <" INTPTR_FORMAT "> (a %s)", "parking to wait for ", p2i(obj), k->external_name());
     }
-    else if (thread()->osthread()->get_state() == CONDVAR_WAIT) {
-      // We are waiting on the native class initialization monitor.
+    else if (thread()->osthread()->get_state() == OBJECT_WAIT) {
+      // We are waiting on an Object monitor but Object.wait() isn't the
+      // top-frame, so we should be waiting on a Class initialization monitor.
       InstanceKlass* k = thread()->class_to_be_initialized();
       if (k != nullptr) {
         st->print_cr("\t- waiting on the Class initialization monitor for %s", k->external_name());

src/hotspot/share/runtime/vmStructs.cpp

@@ -246,6 +246,7 @@
   nonstatic_field(InstanceKlass,               _nonstatic_oop_map_size,                       int)                                   \
   volatile_nonstatic_field(InstanceKlass,      _init_state,                                   InstanceKlass::ClassState)             \
   volatile_nonstatic_field(InstanceKlass,      _init_thread,                                  JavaThread*)                           \
+  nonstatic_field(InstanceKlass,               _is_marked_dependent,                          bool)                                  \
   nonstatic_field(InstanceKlass,               _itable_len,                                   int)                                   \
   nonstatic_field(InstanceKlass,               _nest_host_index,                              u2)                                    \
   nonstatic_field(InstanceKlass,               _reference_type,                               u1)                                    \
@@ -2163,7 +2164,6 @@
                                                                           \
   declare_constant(InstanceKlass::allocated)                              \
   declare_constant(InstanceKlass::loaded)                                 \
-  declare_constant(InstanceKlass::being_linked)                           \
   declare_constant(InstanceKlass::linked)                                 \
   declare_constant(InstanceKlass::being_initialized)                      \
   declare_constant(InstanceKlass::fully_initialized)                      \

src/hotspot/share/services/classLoadingService.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 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
@@ -128,6 +128,22 @@ bool ClassLoadingService::set_verbose(bool verbose) {
   return verbose;
 }
 
+bool ClassLoadingService::get_verbose() {
+  for (LogTagSet* ts = LogTagSet::first(); ts != nullptr; ts = ts->next()) {
+    // set_verbose looks for a non-exact match for class+load,
+    // so look for all tag sets that match class+load*
+    if (ts->contains(LogTag::_class) &&
+        ts->contains(LogTag::_load)) {
+      LogLevelType l = ts->level_for(LogConfiguration::StdoutLog);
+      if (l != LogLevel::Info && l != LogLevel::Debug && l != LogLevel::Trace) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
 // Caller to this function must own Management_lock
 void ClassLoadingService::reset_trace_class_unloading() {
   assert(Management_lock->owned_by_self(), "Must own the Management_lock");

src/hotspot/share/services/classLoadingService.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 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
@@ -53,6 +53,7 @@ class ClassLoadingService : public AllStatic {
  public:
   static void init() NOT_MANAGEMENT_RETURN;
   static bool set_verbose(bool verbose) NOT_MANAGEMENT_RETURN_(false);
+  static bool get_verbose() NOT_MANAGEMENT_RETURN_(false);
   static void reset_trace_class_unloading() NOT_MANAGEMENT_RETURN;
   static jlong loaded_class_count() NOT_MANAGEMENT_RETURN_(0L);
   static jlong unloaded_class_count() NOT_MANAGEMENT_RETURN_(0L);
@@ -63,7 +64,6 @@ class ClassLoadingService : public AllStatic {
   static jlong loaded_shared_class_bytes() NOT_MANAGEMENT_RETURN_(0L);
   static jlong unloaded_shared_class_bytes() NOT_MANAGEMENT_RETURN_(0L);
   static jlong class_method_data_size() NOT_MANAGEMENT_RETURN_(0L);
-  static bool get_verbose() { return log_is_enabled(Info, class, load); }
 
   static void notify_class_loaded(InstanceKlass* k, bool shared_class)
       NOT_MANAGEMENT_RETURN;

src/hotspot/share/services/heapDumper.cpp

@@ -1089,6 +1089,14 @@ u4 DumperSupport::get_static_fields_size(InstanceKlass* ik, u2& field_count) {
     }
   }
 
+  // Also provide a pointer to the init_lock if present, so there aren't unreferenced int[0]
+  // arrays.
+  oop init_lock = ik->init_lock();
+  if (init_lock != nullptr) {
+    field_count++;
+    size += sizeof(address);
+  }
+
   // We write the value itself plus a name and a one byte type tag per field.
   return checked_cast<u4>(size + field_count * (sizeof(address) + 1));
 }
@@ -1126,6 +1134,14 @@ void DumperSupport::dump_static_fields(AbstractDumpWriter* writer, Klass* k) {
       prev = prev->previous_versions();
     }
   }
+
+  // Add init lock to the end if the class is not yet initialized
+  oop init_lock = ik->init_lock();
+  if (init_lock != nullptr) {
+    writer->write_symbolID(vmSymbols::init_lock_name());         // name
+    writer->write_u1(sig2tag(vmSymbols::int_array_signature())); // type
+    writer->write_objectID(init_lock);
+  }
 }
 
 // dump the raw values of the instance fields of the given object

src/hotspot/share/services/memoryService.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 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
@@ -202,6 +202,21 @@ bool MemoryService::set_verbose(bool verbose) {
   return verbose;
 }
 
+bool MemoryService::get_verbose() {
+  for (LogTagSet* ts = LogTagSet::first(); ts != nullptr; ts = ts->next()) {
+    // set_verbose only sets gc and not gc*, so check for an exact match
+    const bool is_gc_exact_match = ts->contains(LogTag::_gc) && ts->ntags() == 1;
+    if (is_gc_exact_match) {
+      LogLevelType l = ts->level_for(LogConfiguration::StdoutLog);
+      if (l == LogLevel::Info || l == LogLevel::Debug || l == LogLevel::Trace) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
 Handle MemoryService::create_MemoryUsage_obj(MemoryUsage usage, TRAPS) {
   InstanceKlass* ik = Management::java_lang_management_MemoryUsage_klass(CHECK_NH);
 

src/hotspot/share/services/memoryService.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 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
@@ -106,8 +106,8 @@ public:
                      GCCause::Cause cause,
                      bool allMemoryPoolsAffected, const char* notificationMessage = nullptr);
 
-  static bool get_verbose() { return log_is_enabled(Info, gc); }
   static bool set_verbose(bool verbose);
+  static bool get_verbose();
 
   // Create an instance of java/lang/management/MemoryUsage
   static Handle create_MemoryUsage_obj(MemoryUsage usage, TRAPS);

src/hotspot/share/utilities/exceptions.cpp

@@ -44,6 +44,9 @@
 #include "utilities/events.hpp"
 #include "utilities/exceptions.hpp"
 
+// Limit exception message components to 64K (the same max as Symbols)
+#define MAX_LEN 65535
+
 // Implementation of ThreadShadow
 void check_ThreadShadow() {
   const ByteSize offset1 = byte_offset_of(ThreadShadow, _pending_exception);
@@ -116,10 +119,11 @@ bool Exceptions::special_exception(JavaThread* thread, const char* file, int lin
     const char* exc_value = h_exception.not_null() ? h_exception->print_value_string() :
                       h_name != nullptr ? h_name->as_C_string() :
                       "null";
-    log_info(exceptions)("Thread cannot call Java so instead of throwing exception <%s%s%s> (" PTR_FORMAT ") \n"
+    log_info(exceptions)("Thread cannot call Java so instead of throwing exception <%.*s%s%.*s> (" PTR_FORMAT ") \n"
                         "at [%s, line %d]\nfor thread " PTR_FORMAT ",\n"
                         "throwing pre-allocated exception: %s",
-                        exc_value, message ? ": " : "", message ? message : "",
+                        MAX_LEN, exc_value, message ? ": " : "",
+                        MAX_LEN, message ? message : "",
                         p2i(h_exception()), file, line, p2i(thread),
                         Universe::vm_exception()->print_value_string());
     // We do not care what kind of exception we get for a thread which
@@ -145,10 +149,11 @@ void Exceptions::_throw(JavaThread* thread, const char* file, int line, Handle h
 
   // tracing (do this up front - so it works during boot strapping)
   // Note, the print_value_string() argument is not called unless logging is enabled!
-  log_info(exceptions)("Exception <%s%s%s> (" PTR_FORMAT ") \n"
+  log_info(exceptions)("Exception <%.*s%s%.*s> (" PTR_FORMAT ") \n"
                        "thrown [%s, line %d]\nfor thread " PTR_FORMAT,
-                       h_exception->print_value_string(),
-                       message ? ": " : "", message ? message : "",
+                       MAX_LEN, h_exception->print_value_string(),
+                       message ? ": " : "",
+                       MAX_LEN, message ? message : "",
                        p2i(h_exception()), file, line, p2i(thread));
 
   // for AbortVMOnException flag
@@ -568,13 +573,13 @@ void Exceptions::log_exception(Handle exception, const char* message) {
   ResourceMark rm;
   const char* detail_message = java_lang_Throwable::message_as_utf8(exception());
   if (detail_message != nullptr) {
-    log_info(exceptions)("Exception <%s: %s>\n thrown in %s",
-                         exception->print_value_string(),
-                         detail_message,
-                         message);
+    log_info(exceptions)("Exception <%.*s: %.*s>\n thrown in %.*s",
+                         MAX_LEN, exception->print_value_string(),
+                         MAX_LEN, detail_message,
+                         MAX_LEN, message);
   } else {
-    log_info(exceptions)("Exception <%s>\n thrown in %s",
-                         exception->print_value_string(),
-                         message);
+    log_info(exceptions)("Exception <%.*s>\n thrown in %.*s",
+                         MAX_LEN, exception->print_value_string(),
+                         MAX_LEN, message);
   }
 }

src/hotspot/share/utilities/utf8.cpp

@@ -24,6 +24,7 @@
 
 #include "precompiled.hpp"
 #include "memory/allocation.hpp"
+#include "utilities/checkedCast.hpp"
 #include "utilities/debug.hpp"
 #include "utilities/globalDefinitions.hpp"
 #include "utilities/utf8.hpp"
@@ -431,12 +432,16 @@ int UNICODE::utf8_size(jbyte c) {
 
 template<typename T>
 int UNICODE::utf8_length(const T* base, int length) {
-  int result = 0;
+  size_t result = 0;
   for (int index = 0; index < length; index++) {
     T c = base[index];
-    result += utf8_size(c);
+    int sz = utf8_size(c);
+    if (result + sz > INT_MAX-1) {
+      break;
+    }
+    result += sz;
   }
-  return result;
+  return checked_cast<int>(result);
 }
 
 template<typename T>

src/java.base/share/classes/java/lang/Object.java

@@ -237,6 +237,10 @@ public class Object {
 
     /**
      * {@return a string representation of the object}
+     *
+     * Satisfying this method's contract implies a non-{@code null}
+     * result must be returned.
+     *
      * @apiNote
      * In general, the
      * {@code toString} method returns a string that

src/java.base/share/classes/java/lang/classfile/CodeBuilder.java

@@ -86,7 +86,7 @@ import java.lang.classfile.instruction.TypeCheckInstruction;
 
 import static java.util.Objects.requireNonNull;
 import static jdk.internal.classfile.impl.BytecodeHelpers.handleDescToHandleInfo;
-import jdk.internal.classfile.impl.TransformingCodeBuilder;
+
 import jdk.internal.javac.PreviewFeature;
 
 /**
@@ -171,7 +171,7 @@ public sealed interface CodeBuilder
     default CodeBuilder transforming(CodeTransform transform, Consumer<CodeBuilder> handler) {
         var resolved = transform.resolve(this);
         resolved.startHandler().run();
-        handler.accept(new TransformingCodeBuilder(this, resolved.consumer()));
+        handler.accept(new ChainedCodeBuilder(this, resolved.consumer()));
         resolved.endHandler().run();
         return this;
     }

src/java.base/share/classes/java/lang/doc-files/ValueBased.html

@@ -1,6 +1,6 @@
 <!doctype html>
 <!--
- Copyright (c) 2013, 2020, Oracle and/or its affiliates. All rights reserved.
+ Copyright (c) 2013, 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
@@ -26,7 +26,6 @@
 <html lang="en">
 <head>
   <title>Value-based Classes</title>
-  <link rel="stylesheet" type="text/css" href="../../../../stylesheet.css" title="Style">
 </head>
 <body>
 <h1 id="ValueBased">{@index "Value-based Classes"}</h1>

src/java.base/share/classes/java/lang/doc-files/threadPrimitiveDeprecation.html

@@ -1,6 +1,6 @@
 <!doctype html>
 <!--
- Copyright (c) 2005, 2023, Oracle and/or its affiliates. All rights reserved.
+ Copyright (c) 2005, 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
@@ -26,7 +26,6 @@
 <html lang="en">
 <head>
   <title>Java Thread Primitive Deprecation</title>
-  <link rel="stylesheet" type="text/css" href="../../../../stylesheet.css" title="Style">
 </head>
 <body>
 <h1>Java Thread Primitive Deprecation</h1>

src/java.base/share/classes/java/lang/foreign/Linker.java

@@ -222,7 +222,7 @@ import java.util.stream.Stream;
  * <pre>
  * MemoryLayout.structLayout(
  *     ValueLayout.JAVA_INT.withName("x"),
- *     MemoryLayout.paddingLayout(32),
+ *     MemoryLayout.paddingLayout(4),
  *     ValueLayout.JAVA_LONG.withName("y")
  * );
  * </pre>

src/java.base/share/classes/java/lang/foreign/MemoryLayout.java

@@ -369,7 +369,7 @@ import jdk.internal.foreign.layout.UnionLayoutImpl;
  * int size = ...
  * MemorySegment points = ...
  * for (int i = 0 ; i < size ; i++) {
- *     ... POINT_ARR_X.get(segment, 0L, (long)i) ...
+ *     ... POINT_ARR_X.get(points, 0L, (long)i) ...
  * }
  * }
  *

src/java.base/share/classes/java/lang/foreign/MemorySegment.java

@@ -630,6 +630,12 @@ public sealed interface MemorySegment permits AbstractMemorySegmentImpl {
      * {@snippet lang=java :
      * asSlice(offset, newSize, 1);
      * }
+     * <p>
+     * If this segment is {@linkplain MemorySegment#isReadOnly() read-only},
+     * the returned segment is also {@linkplain MemorySegment#isReadOnly() read-only}.
+     * <p>
+     * The returned memory segment shares a region of backing memory with this segment.
+     * Hence, no memory will be allocated or freed by this method.
      *
      * @see #asSlice(long, long, long)
      *
@@ -646,6 +652,12 @@ public sealed interface MemorySegment permits AbstractMemorySegmentImpl {
      * Returns a slice of this memory segment, at the given offset, with the provided
      * alignment constraint. The returned segment's address is the address of this
      * segment plus the given offset; its size is specified by the given argument.
+     * <p>
+     * If this segment is {@linkplain MemorySegment#isReadOnly() read-only},
+     * the returned segment is also {@linkplain MemorySegment#isReadOnly() read-only}.
+     * <p>
+     * The returned memory segment shares a region of backing memory with this segment.
+     * Hence, no memory will be allocated or freed by this method.
      *
      * @param offset The new segment base offset (relative to the address of this segment),
      *               specified in bytes
@@ -670,6 +682,12 @@ public sealed interface MemorySegment permits AbstractMemorySegmentImpl {
      * {@snippet lang=java :
      * asSlice(offset, layout.byteSize(), layout.byteAlignment());
      * }
+     * <p>
+     * If this segment is {@linkplain MemorySegment#isReadOnly() read-only},
+     * the returned segment is also {@linkplain MemorySegment#isReadOnly() read-only}.
+     * <p>
+     * The returned memory segment shares a region of backing memory with this segment.
+     * Hence, no memory will be allocated or freed by this method.
      *
      * @see #asSlice(long, long, long)
      *
@@ -693,6 +711,12 @@ public sealed interface MemorySegment permits AbstractMemorySegmentImpl {
      * {@snippet lang=java :
      * asSlice(offset, byteSize() - offset);
      * }
+     * <p>
+     * If this segment is {@linkplain MemorySegment#isReadOnly() read-only},
+     * the returned segment is also {@linkplain MemorySegment#isReadOnly() read-only}.
+     * <p>
+     * The returned memory segment shares a region of backing memory with this segment.
+     * Hence, no memory will be allocated or freed by this method.
      *
      * @see #asSlice(long, long)
      *
@@ -706,6 +730,12 @@ public sealed interface MemorySegment permits AbstractMemorySegmentImpl {
     /**
      * Returns a new memory segment that has the same address and scope as this segment,
      * but with the provided size.
+     * <p>
+     * If this segment is {@linkplain MemorySegment#isReadOnly() read-only},
+     * the returned segment is also {@linkplain MemorySegment#isReadOnly() read-only}.
+     * <p>
+     * The returned memory segment shares a region of backing memory with this segment.
+     * Hence, no memory will be allocated or freed by this method.
      *
      * @param newSize the size of the returned segment
      * @return a new memory segment that has the same address and scope as
@@ -741,6 +771,12 @@ public sealed interface MemorySegment permits AbstractMemorySegmentImpl {
      * That is, the cleanup action receives a segment that is associated with the global
      * scope, and is accessible from any thread. The size of the segment accepted by the
      * cleanup action is {@link #byteSize()}.
+     * <p>
+     * If this segment is {@linkplain MemorySegment#isReadOnly() read-only},
+     * the returned segment is also {@linkplain MemorySegment#isReadOnly() read-only}.
+     * <p>
+     * The returned memory segment shares a region of backing memory with this segment.
+     * Hence, no memory will be allocated or freed by this method.
      *
      * @apiNote The cleanup action (if present) should take care not to leak the received
      *          segment to external clients that might access the segment after its
@@ -786,6 +822,12 @@ public sealed interface MemorySegment permits AbstractMemorySegmentImpl {
      * That is, the cleanup action receives a segment that is associated with the global
      * scope, and is accessible from any thread. The size of the segment accepted by the
      * cleanup action is {@code newSize}.
+     * <p>
+     * If this segment is {@linkplain MemorySegment#isReadOnly() read-only},
+     * the returned segment is also {@linkplain MemorySegment#isReadOnly() read-only}.
+     * <p>
+     * The returned memory segment shares a region of backing memory with this segment.
+     * Hence, no memory will be allocated or freed by this method.
      *
      * @apiNote The cleanup action (if present) should take care not to leak the received
      *          segment to external clients that might access the segment after its

src/java.base/share/classes/java/lang/reflect/ProxyGenerator.java

@@ -39,7 +39,6 @@ import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
 import java.util.Objects;
-import jdk.internal.constant.ConstantUtils;
 import jdk.internal.constant.MethodTypeDescImpl;
 import jdk.internal.constant.ReferenceClassDescImpl;
 import sun.security.action.GetBooleanAction;
@@ -47,10 +46,7 @@ import sun.security.action.GetBooleanAction;
 import static java.lang.classfile.ClassFile.*;
 import java.lang.classfile.attribute.StackMapFrameInfo;
 import java.lang.classfile.attribute.StackMapTableAttribute;
-import java.lang.constant.ConstantDescs;
 import static java.lang.constant.ConstantDescs.*;
-import java.lang.constant.DirectMethodHandleDesc;
-import java.lang.constant.DynamicConstantDesc;
 
 /**
  * ProxyGenerator contains the code to generate a dynamic proxy class
@@ -65,7 +61,10 @@ final class ProxyGenerator {
             ClassFile.of(ClassFile.StackMapsOption.DROP_STACK_MAPS);
 
     private static final ClassDesc
+            CD_ClassLoader = ReferenceClassDescImpl.ofValidated("Ljava/lang/ClassLoader;"),
             CD_Class_array = ReferenceClassDescImpl.ofValidated("[Ljava/lang/Class;"),
+            CD_ClassNotFoundException = ReferenceClassDescImpl.ofValidated("Ljava/lang/ClassNotFoundException;"),
+            CD_NoClassDefFoundError = ReferenceClassDescImpl.ofValidated("Ljava/lang/NoClassDefFoundError;"),
             CD_IllegalAccessException = ReferenceClassDescImpl.ofValidated("Ljava/lang/IllegalAccessException;"),
             CD_InvocationHandler = ReferenceClassDescImpl.ofValidated("Ljava/lang/reflect/InvocationHandler;"),
             CD_Method = ReferenceClassDescImpl.ofValidated("Ljava/lang/reflect/Method;"),
@@ -81,8 +80,9 @@ final class ProxyGenerator {
             MTD_void_String = MethodTypeDescImpl.ofValidated(CD_void, CD_String),
             MTD_void_Throwable = MethodTypeDescImpl.ofValidated(CD_void, CD_Throwable),
             MTD_Class = MethodTypeDescImpl.ofValidated(CD_Class),
-            MTD_Class_array = MethodTypeDescImpl.ofValidated(CD_Class_array),
-            MTD_Method_String_Class_array = MethodTypeDescImpl.ofValidated(CD_Method, ConstantDescs.CD_String, CD_Class_array),
+            MTD_Class_String_boolean_ClassLoader = MethodTypeDescImpl.ofValidated(CD_Class, CD_String, CD_boolean, CD_ClassLoader),
+            MTD_ClassLoader = MethodTypeDescImpl.ofValidated(CD_ClassLoader),
+            MTD_Method_String_Class_array = MethodTypeDescImpl.ofValidated(CD_Method, CD_String, CD_Class_array),
             MTD_MethodHandles$Lookup = MethodTypeDescImpl.ofValidated(CD_MethodHandles_Lookup),
             MTD_MethodHandles$Lookup_MethodHandles$Lookup = MethodTypeDescImpl.ofValidated(CD_MethodHandles_Lookup, CD_MethodHandles_Lookup),
             MTD_Object_Object_Method_ObjectArray = MethodTypeDescImpl.ofValidated(CD_Object, CD_Object, CD_Method, CD_Object_array),
@@ -107,34 +107,33 @@ final class ProxyGenerator {
                             "jdk.proxy.ProxyGenerator.saveGeneratedFiles"));
 
     /* Preloaded ProxyMethod objects for methods in java.lang.Object */
-    private static final ProxyMethod HASH_CODE_METHOD;
-    private static final ProxyMethod EQUALS_METHOD;
-    private static final ProxyMethod TO_STRING_METHOD;
+    private static final Method OBJECT_HASH_CODE_METHOD;
+    private static final Method OBJECT_EQUALS_METHOD;
+    private static final Method OBJECT_TO_STRING_METHOD;
 
     static {
         try {
-            HASH_CODE_METHOD = new ProxyMethod(Object.class.getMethod("hashCode"));
-            EQUALS_METHOD = new ProxyMethod(Object.class.getMethod("equals", Object.class));
-            TO_STRING_METHOD = new ProxyMethod(Object.class.getMethod("toString"));
+            OBJECT_HASH_CODE_METHOD = Object.class.getMethod("hashCode");
+            OBJECT_EQUALS_METHOD = Object.class.getMethod("equals", Object.class);
+            OBJECT_TO_STRING_METHOD = Object.class.getMethod("toString");
         } catch (NoSuchMethodException e) {
             throw new NoSuchMethodError(e.getMessage());
         }
     }
 
     private final ConstantPoolBuilder cp;
-    private final List<StackMapFrameInfo.VerificationTypeInfo> throwableStack;
+    private final List<StackMapFrameInfo.VerificationTypeInfo> classLoaderLocal, throwableStack;
     private final NameAndTypeEntry exInit;
-    private final ClassEntry object, proxy, ute;
+    private final ClassEntry objectCE, proxyCE, uteCE, classCE;
     private final FieldRefEntry handlerField;
-    private final InterfaceMethodRefEntry invoke;
-    private final MethodRefEntry uteInit;
-    private final DirectMethodHandleDesc bsm;
+    private final InterfaceMethodRefEntry invocationHandlerInvoke;
+    private final MethodRefEntry uteInit, classGetMethod, classForName, throwableGetMessage;
 
 
     /**
-     * Name of proxy class
+     * ClassEntry for this proxy class
      */
-    private ClassEntry classEntry;
+    private final ClassEntry thisClassCE;
 
     /**
      * Proxy interfaces
@@ -153,6 +152,12 @@ final class ProxyGenerator {
      */
     private final Map<String, List<ProxyMethod>> proxyMethods = new LinkedHashMap<>();
 
+    /**
+     * Ordinal of next ProxyMethod object added to proxyMethods.
+     * Indexes are reserved for hashcode(0), equals(1), toString(2).
+     */
+    private int proxyMethodCount = 3;
+
     /**
      * Construct a ProxyGenerator to generate a proxy class with the
      * specified name and for the given interfaces.
@@ -163,18 +168,23 @@ final class ProxyGenerator {
     private ProxyGenerator(ClassLoader loader, String className, List<Class<?>> interfaces,
                            int accessFlags) {
         this.cp = ConstantPoolBuilder.of();
-        this.classEntry = cp.classEntry(ReferenceClassDescImpl.ofValidatedBinaryName(className));
+        this.thisClassCE = cp.classEntry(ReferenceClassDescImpl.ofValidatedBinaryName(className));
         this.interfaces = interfaces;
         this.accessFlags = accessFlags;
-        this.throwableStack = List.of(StackMapFrameInfo.ObjectVerificationTypeInfo.of(cp.classEntry(CD_Throwable)));
+        var throwable = cp.classEntry(CD_Throwable);
+        this.classLoaderLocal = List.of(StackMapFrameInfo.ObjectVerificationTypeInfo.of(cp.classEntry(CD_ClassLoader)));
+        this.throwableStack = List.of(StackMapFrameInfo.ObjectVerificationTypeInfo.of(throwable));
         this.exInit = cp.nameAndTypeEntry(INIT_NAME, MTD_void_String);
-        this.object = cp.classEntry(CD_Object);
-        this.proxy = cp.classEntry(CD_Proxy);
-        this.handlerField = cp.fieldRefEntry(proxy, cp.nameAndTypeEntry(NAME_HANDLER_FIELD, CD_InvocationHandler));
-        this.invoke = cp.interfaceMethodRefEntry(CD_InvocationHandler, "invoke", MTD_Object_Object_Method_ObjectArray);
-        this.ute = cp.classEntry(CD_UndeclaredThrowableException);
-        this.uteInit = cp.methodRefEntry(ute, cp.nameAndTypeEntry(INIT_NAME, MTD_void_Throwable));
-        this.bsm = ConstantDescs.ofConstantBootstrap(classEntry.asSymbol(), "$getMethod", CD_Method, CD_Class, CD_String, CD_MethodType);
+        this.objectCE = cp.classEntry(CD_Object);
+        this.proxyCE = cp.classEntry(CD_Proxy);
+        this.classCE = cp.classEntry(CD_Class);
+        this.handlerField = cp.fieldRefEntry(proxyCE, cp.nameAndTypeEntry(NAME_HANDLER_FIELD, CD_InvocationHandler));
+        this.invocationHandlerInvoke = cp.interfaceMethodRefEntry(CD_InvocationHandler, "invoke", MTD_Object_Object_Method_ObjectArray);
+        this.uteCE = cp.classEntry(CD_UndeclaredThrowableException);
+        this.uteInit = cp.methodRefEntry(uteCE, cp.nameAndTypeEntry(INIT_NAME, MTD_void_Throwable));
+        this.classGetMethod = cp.methodRefEntry(classCE, cp.nameAndTypeEntry("getMethod", MTD_Method_String_Class_array));
+        this.classForName = cp.methodRefEntry(classCE, cp.nameAndTypeEntry("forName", MTD_Class_String_boolean_ClassLoader));
+        this.throwableGetMessage = cp.methodRefEntry(throwable, cp.nameAndTypeEntry("getMessage", MTD_String));
     }
 
     /**
@@ -441,9 +451,9 @@ final class ProxyGenerator {
          * java.lang.Object take precedence over duplicate methods in the
          * proxy interfaces.
          */
-        addProxyMethod(HASH_CODE_METHOD);
-        addProxyMethod(EQUALS_METHOD);
-        addProxyMethod(TO_STRING_METHOD);
+        addProxyMethod(new ProxyMethod(OBJECT_HASH_CODE_METHOD, "m0"));
+        addProxyMethod(new ProxyMethod(OBJECT_EQUALS_METHOD, "m1"));
+        addProxyMethod(new ProxyMethod(OBJECT_TO_STRING_METHOD, "m2"));
 
         /*
          * Accumulate all of the methods from the proxy interfaces.
@@ -464,20 +474,23 @@ final class ProxyGenerator {
             checkReturnTypes(sigmethods);
         }
 
-        return CF_CONTEXT.build(classEntry, cp, clb -> {
-            clb.withSuperclass(proxy);
+        return CF_CONTEXT.build(thisClassCE, cp, clb -> {
+            clb.withSuperclass(proxyCE);
             clb.withFlags(accessFlags);
             clb.withInterfaces(toClassEntries(cp, interfaces));
             generateConstructor(clb);
 
             for (List<ProxyMethod> sigmethods : proxyMethods.values()) {
                 for (ProxyMethod pm : sigmethods) {
+                    // add static field for the Method object
+                    clb.withField(pm.methodFieldName, CD_Method, ACC_PRIVATE | ACC_STATIC | ACC_FINAL);
+
                     // Generate code for proxy method
-                    pm.generateMethod(this, clb);
+                    pm.generateMethod(clb);
                 }
             }
 
-            generateBootstrapMethod(clb);
+            generateStaticInitializer(clb);
             generateLookupAccessor(clb);
         });
     }
@@ -520,7 +533,7 @@ final class ProxyGenerator {
             }
         }
         sigmethods.add(new ProxyMethod(m, sig, m.getSharedParameterTypes(), returnType,
-                exceptionTypes, fromClass));
+                exceptionTypes, fromClass, "m" + proxyMethodCount++));
     }
 
     /**
@@ -542,32 +555,56 @@ final class ProxyGenerator {
         clb.withMethodBody(INIT_NAME, MTD_void_InvocationHandler, ACC_PUBLIC, cob -> cob
                .aload(0)
                .aload(1)
-               .invokespecial(cp.methodRefEntry(proxy, cp.nameAndTypeEntry(INIT_NAME, MTD_void_InvocationHandler)))
+               .invokespecial(cp.methodRefEntry(proxyCE,
+                   cp.nameAndTypeEntry(INIT_NAME, MTD_void_InvocationHandler)))
                .return_());
     }
 
     /**
-     * Generate CONDY bootstrap method for the proxy class to retrieve {@link Method} instances.
+     * Generate the class initializer.
+     * Discussion: Currently, for Proxy to work with SecurityManager,
+     * we rely on the parameter classes of the methods to be computed
+     * from Proxy instead of via user code paths like bootstrap method
+     * lazy evaluation. That might change if we can pass in the live
+     * Method objects directly..
      */
-    private void generateBootstrapMethod(ClassBuilder clb) {
-        clb.withMethodBody(bsm.methodName(), bsm.invocationType(), ClassFile.ACC_PRIVATE | ClassFile.ACC_STATIC, cob -> {
-            cob.aload(3) //interface Class
-               .aload(4) //interface method name String
-               .aload(5) //interface MethodType
-               .invokevirtual(CD_MethodType, "parameterArray", MTD_Class_array)
-               .invokevirtual(ConstantDescs.CD_Class, "getMethod", MTD_Method_String_Class_array)
-               .areturn();
-            Label failLabel = cob.newBoundLabel();
-            ClassEntry nsme = cp.classEntry(CD_NoSuchMethodError);
-            cob.exceptionCatch(cob.startLabel(), failLabel, failLabel, CD_NoSuchMethodException)
-               .new_(nsme)
+    private void generateStaticInitializer(ClassBuilder clb) {
+        clb.withMethodBody(CLASS_INIT_NAME, MTD_void, ACC_STATIC, cob -> {
+            // Put ClassLoader at local variable index 0, used by
+            // Class.forName(String, boolean, ClassLoader) calls
+            cob.ldc(thisClassCE)
+               .invokevirtual(cp.methodRefEntry(classCE,
+                       cp.nameAndTypeEntry("getClassLoader", MTD_ClassLoader)))
+               .astore(0);
+            var ts = cob.newBoundLabel();
+            for (List<ProxyMethod> sigmethods : proxyMethods.values()) {
+                for (ProxyMethod pm : sigmethods) {
+                    pm.codeFieldInitialization(cob);
+                }
+            }
+            cob.return_();
+            var c1 = cob.newBoundLabel();
+            var nsmError = cp.classEntry(CD_NoSuchMethodError);
+            cob.exceptionCatch(ts, c1, c1, CD_NoSuchMethodException)
+               .new_(nsmError)
                .dup_x1()
                .swap()
-               .invokevirtual(cp.methodRefEntry(CD_Throwable, "getMessage", MTD_String))
-               .invokespecial(cp.methodRefEntry(nsme, exInit))
-               .athrow()
-               .with(StackMapTableAttribute.of(List.of(
-                       StackMapFrameInfo.of(failLabel, List.of(), throwableStack))));
+               .invokevirtual(throwableGetMessage)
+               .invokespecial(cp.methodRefEntry(nsmError, exInit))
+               .athrow();
+            var c2 = cob.newBoundLabel();
+            var ncdfError = cp.classEntry(CD_NoClassDefFoundError);
+            cob.exceptionCatch(ts, c1, c2, CD_ClassNotFoundException)
+               .new_(ncdfError)
+               .dup_x1()
+               .swap()
+               .invokevirtual(throwableGetMessage)
+               .invokespecial(cp.methodRefEntry(ncdfError, exInit))
+               .athrow();
+            cob.with(StackMapTableAttribute.of(List.of(
+                       StackMapFrameInfo.of(c1, classLoaderLocal, throwableStack),
+                       StackMapFrameInfo.of(c2, classLoaderLocal, throwableStack))));
+
         });
     }
 
@@ -587,7 +624,7 @@ final class ProxyGenerator {
                             ClassEntry iae = cp.classEntry(CD_IllegalAccessException);
                             cob.aload(cob.parameterSlot(0))
                                .invokevirtual(cp.methodRefEntry(mhl, cp.nameAndTypeEntry("lookupClass", MTD_Class)))
-                               .ldc(proxy)
+                               .ldc(proxyCE)
                                .if_acmpne(failLabel)
                                .aload(cob.parameterSlot(0))
                                .invokevirtual(cp.methodRefEntry(mhl, cp.nameAndTypeEntry("hasFullPrivilegeAccess", MTD_boolean)))
@@ -613,24 +650,29 @@ final class ProxyGenerator {
      * being generated: a method whose implementation will encode and
      * dispatch invocations to the proxy instance's invocation handler.
      */
-    private static class ProxyMethod {
+    private class ProxyMethod {
 
         private final Method method;
         private final String shortSignature;
         private final Class<?> fromClass;
         private final Class<?>[] parameterTypes;
         private final Class<?> returnType;
+        private final String methodFieldName;
         private Class<?>[] exceptionTypes;
+        private final FieldRefEntry methodField;
 
         private ProxyMethod(Method method, String sig, Class<?>[] parameterTypes,
                             Class<?> returnType, Class<?>[] exceptionTypes,
-                            Class<?> fromClass) {
+                            Class<?> fromClass, String methodFieldName) {
             this.method = method;
             this.shortSignature = sig;
             this.parameterTypes = parameterTypes;
             this.returnType = returnType;
             this.exceptionTypes = exceptionTypes;
             this.fromClass = fromClass;
+            this.methodFieldName = methodFieldName;
+            this.methodField = cp.fieldRefEntry(thisClassCE,
+                cp.nameAndTypeEntry(methodFieldName, CD_Method));
         }
 
         /**
@@ -639,17 +681,16 @@ final class ProxyGenerator {
          * @param method          The method for which to create a proxy
          * @param methodFieldName the fieldName to generate
          */
-        private ProxyMethod(Method method) {
+        private ProxyMethod(Method method, String methodFieldName) {
             this(method, method.toShortSignature(),
                  method.getSharedParameterTypes(), method.getReturnType(),
-                 method.getSharedExceptionTypes(), method.getDeclaringClass());
+                 method.getSharedExceptionTypes(), method.getDeclaringClass(), methodFieldName);
         }
 
         /**
          * Generate this method, including the code and exception table entry.
          */
-        private void generateMethod(ProxyGenerator pg, ClassBuilder clb) {
-            var cp = pg.cp;
+        private void generateMethod(ClassBuilder clb) {
             var pTypes = new ClassDesc[parameterTypes.length];
             for (int i = 0; i < pTypes.length; i++) {
                 pTypes[i] = toClassDesc(parameterTypes[i]);
@@ -661,17 +702,14 @@ final class ProxyGenerator {
             clb.withMethod(method.getName(), desc, accessFlags, mb ->
                   mb.with(ExceptionsAttribute.of(toClassEntries(cp, List.of(exceptionTypes))))
                     .withCode(cob -> {
-                        cob.aload(0)
-                           .getfield(pg.handlerField)
-                           .aload(0)
-                           .ldc(DynamicConstantDesc.of(pg.bsm,
-                                toClassDesc(fromClass),
-                                method.getName(),
-                                desc));
+                        cob.aload(cob.receiverSlot())
+                           .getfield(handlerField)
+                           .aload(cob.receiverSlot())
+                           .getstatic(methodField);
                         if (parameterTypes.length > 0) {
                             // Create an array and fill with the parameters converting primitives to wrappers
                             cob.loadConstant(parameterTypes.length)
-                               .anewarray(pg.object);
+                               .anewarray(objectCE);
                             for (int i = 0; i < parameterTypes.length; i++) {
                                 cob.dup()
                                    .loadConstant(i);
@@ -682,7 +720,7 @@ final class ProxyGenerator {
                             cob.aconst_null();
                         }
 
-                        cob.invokeinterface(pg.invoke);
+                        cob.invokeinterface(invocationHandlerInvoke);
 
                         if (returnType == void.class) {
                             cob.pop()
@@ -698,14 +736,14 @@ final class ProxyGenerator {
                             cob.athrow();   // just rethrow the exception
                             var c2 = cob.newBoundLabel();
                             cob.exceptionCatchAll(cob.startLabel(), c1, c2)
-                               .new_(pg.ute)
+                               .new_(uteCE)
                                .dup_x1()
                                .swap()
-                               .invokespecial(pg.uteInit)
+                               .invokespecial(uteInit)
                                .athrow()
                                .with(StackMapTableAttribute.of(List.of(
-                                       StackMapFrameInfo.of(c1, List.of(), pg.throwableStack),
-                                       StackMapFrameInfo.of(c2, List.of(), pg.throwableStack))));
+                                    StackMapFrameInfo.of(c1, List.of(), throwableStack),
+                                    StackMapFrameInfo.of(c2, List.of(), throwableStack))));
                         }
                     }));
         }
@@ -720,7 +758,7 @@ final class ProxyGenerator {
             if (type.isPrimitive()) {
                 cob.loadLocal(TypeKind.from(type).asLoadable(), slot);
                 PrimitiveTypeInfo prim = PrimitiveTypeInfo.get(type);
-                cob.invokestatic(prim.wrapperMethodRef(cob.constantPool()));
+                cob.invokestatic(prim.wrapperMethodRef(cp));
             } else {
                 cob.aload(slot);
             }
@@ -736,7 +774,7 @@ final class ProxyGenerator {
                 PrimitiveTypeInfo prim = PrimitiveTypeInfo.get(type);
 
                 cob.checkcast(prim.wrapperClass)
-                   .invokevirtual(prim.unwrapMethodRef(cob.constantPool()))
+                   .invokevirtual(prim.unwrapMethodRef(cp))
                    .return_(TypeKind.from(type).asLoadable());
             } else {
                 cob.checkcast(toClassDesc(type))
@@ -744,6 +782,57 @@ final class ProxyGenerator {
             }
         }
 
+        /**
+         * Generate code for initializing the static field that stores
+         * the Method object for this proxy method. A class loader is
+         * anticipated at local variable index 0.
+         * The generated code must be run in an AccessController.doPrivileged
+         * block if a SecurityManager is present, as otherwise the code
+         * cannot pass {@code null} ClassLoader to forName.
+         */
+        private void codeFieldInitialization(CodeBuilder cob) {
+            var cp = cob.constantPool();
+            codeClassForName(cob, fromClass);
+
+            cob.ldc(method.getName())
+               .loadConstant(parameterTypes.length)
+               .anewarray(classCE);
+
+            // Construct an array with the parameter types mapping primitives to Wrapper types
+            for (int i = 0; i < parameterTypes.length; i++) {
+                cob.dup()
+                   .loadConstant(i);
+                if (parameterTypes[i].isPrimitive()) {
+                    PrimitiveTypeInfo prim = PrimitiveTypeInfo.get(parameterTypes[i]);
+                    cob.getstatic(prim.typeFieldRef(cp));
+                } else {
+                    codeClassForName(cob, parameterTypes[i]);
+                }
+                cob.aastore();
+            }
+            // lookup the method
+            cob.invokevirtual(classGetMethod)
+               .putstatic(methodField);
+        }
+
+        /*
+         * =============== Code Generation Utility Methods ===============
+         */
+
+        /**
+         * Generate code to invoke the Class.forName with the name of the given
+         * class to get its Class object at runtime.  The code is written to
+         * the supplied stream.  Note that the code generated by this method
+         * may cause the checked ClassNotFoundException to be thrown. A class
+         * loader is anticipated at local variable index 0.
+         */
+        private void codeClassForName(CodeBuilder cob, Class<?> cl) {
+            cob.ldc(cl.getName())
+               .iconst_0() // false
+               .aload(0)// classLoader
+               .invokestatic(classForName);
+        }
+
         @Override
         public String toString() {
             return method.toShortString();
@@ -810,5 +899,9 @@ final class ProxyGenerator {
         public MethodRefEntry unwrapMethodRef(ConstantPoolBuilder cp) {
             return cp.methodRefEntry(wrapperClass, unwrapMethodName, unwrapMethodType);
         }
+
+        public FieldRefEntry typeFieldRef(ConstantPoolBuilder cp) {
+            return cp.fieldRefEntry(wrapperClass, "TYPE", CD_Class);
+        }
     }
 }

src/java.base/share/classes/java/nio/Heap-X-Buffer.java.template

@@ -29,7 +29,6 @@ package java.nio;
 
 import java.lang.foreign.MemorySegment;
 import java.util.Objects;
-import jdk.internal.util.ArraysSupport;
 
 /**
 #if[rw]
@@ -706,9 +705,6 @@ class Heap$Type$Buffer$RW$
                                                                    addr, segment)));
     }
 
-    public int hashCode() {
-        return ArraysSupport.hashCode(hb, ix(position()), remaining(), 1);
-    }
 
 #end[byte]
 
@@ -737,9 +733,6 @@ class Heap$Type$Buffer$RW$
                                       offset, segment);
     }
 
-    public int hashCode() {
-        return ArraysSupport.hashCode(hb, ix(position()), remaining(), 1);
-    }
 #end[char]
 
 

src/java.base/share/classes/java/util/stream/Gatherer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 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
@@ -293,7 +293,7 @@ public interface Gatherer<T, A, R> {
      *
      * @implSpec This method always returns the same instance.
      *
-     * @see Gatherer#finisher()
+     * @see Gatherer#combiner()
      * @return the instance of the default combiner
      * @param <A> the type of the state of the returned combiner
      */

src/java.base/share/classes/jdk/internal/classfile/impl/AbstractPoolEntry.java

@@ -68,24 +68,19 @@ public abstract sealed class AbstractPoolEntry {
      */
 
     private static final int TAG_SMEAR = 0x13C4B2D1;
-    private static final int INT_PHI = 0x9E3779B9;
+    static final int NON_ZERO = 0x40000000;
 
     public static int hash1(int tag, int x1) {
-        return phiMix(tag * TAG_SMEAR + x1);
+        return (tag * TAG_SMEAR + x1) | NON_ZERO;
     }
 
     public static int hash2(int tag, int x1, int x2) {
-        return phiMix(tag * TAG_SMEAR + x1 + 31*x2);
+        return (tag * TAG_SMEAR + x1 + 31 * x2) | NON_ZERO;
     }
 
     // Ensure that hash is never zero
     public static int hashString(int stringHash) {
-        return phiMix(stringHash | (1 << 30));
-    }
-
-    public static int phiMix(int x) {
-        int h = x * INT_PHI;
-        return h ^ (h >> 16);
+        return stringHash | NON_ZERO;
     }
 
     public static Utf8Entry rawUtf8EntryFromStandardAttributeName(String name) {

src/java.base/share/classes/jdk/internal/classfile/impl/BlockCodeBuilderImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 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
@@ -51,13 +51,13 @@ public final class BlockCodeBuilderImpl
 
     public void start() {
         topLocal = topLocal(parent);
-        terminalMaxLocals = topLocal(terminal);
-        terminal.with((LabelTarget) startLabel);
+        terminalMaxLocals = terminal.curTopLocal();
+        parent.with((LabelTarget) startLabel);
     }
 
     public void end() {
-        terminal.with((LabelTarget) endLabel);
-        if (terminalMaxLocals != topLocal(terminal)) {
+        parent.with((LabelTarget) endLabel);
+        if (terminalMaxLocals != terminal.curTopLocal()) {
             throw new IllegalStateException("Interference in local variable slot management");
         }
     }
@@ -73,10 +73,8 @@ public final class BlockCodeBuilderImpl
     private int topLocal(CodeBuilder parent) {
         return switch (parent) {
             case BlockCodeBuilderImpl b -> b.topLocal;
-            case ChainedCodeBuilder b -> topLocal(b.terminal);
-            case DirectCodeBuilder b -> b.curTopLocal();
-            case BufferedCodeBuilder b -> b.curTopLocal();
-            case TransformingCodeBuilder b -> topLocal(b.delegate);
+            case ChainedCodeBuilder b -> b.terminal.curTopLocal();
+            case TerminalCodeBuilder b -> b.curTopLocal();
         };
     }
 

src/java.base/share/classes/jdk/internal/classfile/impl/BootstrapMethodEntryImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 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
@@ -76,9 +76,7 @@ public final class BootstrapMethodEntryImpl implements BootstrapMethodEntry {
 
     static int computeHashCode(MethodHandleEntryImpl handle,
                                List<? extends LoadableConstantEntry> arguments) {
-        int hash = handle.hashCode();
-        hash = 31 * hash + arguments.hashCode();
-        return AbstractPoolEntry.phiMix(hash);
+        return (31 * handle.hashCode() + arguments.hashCode()) | AbstractPoolEntry.NON_ZERO;
     }
 
     @Override

src/java.base/share/classes/jdk/internal/classfile/impl/BoundAttribute.java

@@ -988,77 +988,77 @@ public abstract sealed class BoundAttribute<T extends Attribute<T>>
     public static AttributeMapper<?> standardAttribute(Utf8Entry name) {
         // critical bootstrap path, so no lambdas nor method handles here
         return switch (name.hashCode()) {
-            case 0x78147009 ->
+            case 0x46699ff2 ->
                 name.equalsString(NAME_ANNOTATION_DEFAULT) ? annotationDefault() : null;
-            case 0x665e3a3a ->
+            case 0x5208e184 ->
                 name.equalsString(NAME_BOOTSTRAP_METHODS) ? bootstrapMethods() : null;
-            case 0xcb7e162 ->
+            case 0xcb60907a ->
                 name.equalsString(NAME_CHARACTER_RANGE_TABLE) ? characterRangeTable() : null;
-            case 0x21e41e7e ->
+            case 0x4020220d ->
                 name.equalsString(NAME_CODE) ? code() : null;
-            case 0x5a306b41 ->
+            case 0xc20dd1fe ->
                 name.equalsString(NAME_COMPILATION_ID) ? compilationId() : null;
-            case 0x3e191c7c ->
+            case 0xcab1940d ->
                 name.equalsString(NAME_CONSTANT_VALUE) ? constantValue() : null;
-            case 0x5e88ed0c ->
+            case 0x558641d3 ->
                 name.equalsString(NAME_DEPRECATED) ? deprecated() : null;
-            case 0x7284695e ->
+            case 0x51d443cd ->
                 name.equalsString(NAME_ENCLOSING_METHOD) ? enclosingMethod() : null;
-            case 0x21df25db ->
+            case 0x687c1624 ->
                 name.equalsString(NAME_EXCEPTIONS) ? exceptions() : null;
-            case 0x11392da9 ->
+            case 0x7adb2910 ->
                 name.equalsString(NAME_INNER_CLASSES) ? innerClasses() : null;
-            case 0x167536fc ->
+            case 0x653f0551 ->
                 name.equalsString(NAME_LINE_NUMBER_TABLE) ? lineNumberTable() : null;
-            case 0x46939abc ->
+            case 0x64c75927 ->
                 name.equalsString(NAME_LOCAL_VARIABLE_TABLE) ? localVariableTable() : null;
-            case 0x63ee67f4 ->
+            case 0x6697f98d ->
                 name.equalsString(NAME_LOCAL_VARIABLE_TYPE_TABLE) ? localVariableTypeTable() : null;
-            case 0x2b597e15 ->
+            case 0xdbb0cdcb ->
                 name.equalsString(NAME_METHOD_PARAMETERS) ? methodParameters() : null;
-            case 0x19f20ade ->
+            case 0xc9b0928c ->
                 name.equalsString(NAME_MODULE) ? module() : null;
-            case 0x47f6395e ->
+            case 0x41cd27e8 ->
                 name.equalsString(NAME_MODULE_HASHES) ? moduleHashes() : null;
-            case 0x54db809 ->
+            case 0x7deb0a13 ->
                 name.equalsString(NAME_MODULE_MAIN_CLASS) ? moduleMainClass() : null;
-            case 0x1abd1c2c ->
+            case 0x6706ff99 ->
                 name.equalsString(NAME_MODULE_PACKAGES) ? modulePackages() : null;
-            case 0x6ba46dd ->
+            case 0x60272858 ->
                 name.equalsString(NAME_MODULE_RESOLUTION) ? moduleResolution() : null;
-            case 0x46f7d91d ->
+            case 0x5646d73d ->
                 name.equalsString(NAME_MODULE_TARGET) ? moduleTarget() : null;
-            case 0x5137f53 ->
+            case 0x50336c40 ->
                 name.equalsString(NAME_NEST_HOST) ? nestHost() : null;
-            case 0x4a8fa3b6 ->
+            case 0x4735ab81 ->
                 name.equalsString(NAME_NEST_MEMBERS) ? nestMembers() : null;
-            case 0x55c73cb6 ->
+            case 0x7100d9fe ->
                 name.equalsString(NAME_PERMITTED_SUBCLASSES) ? permittedSubclasses() : null;
-            case 0x3fe76d4e ->
+            case 0xd1ab5871 ->
                 name.equalsString(NAME_RECORD) ? record() : null;
-            case 0x180d6925 ->
+            case 0x7588550f ->
                 name.equalsString(NAME_RUNTIME_INVISIBLE_ANNOTATIONS) ? runtimeInvisibleAnnotations() : null;
-            case 0x7be22752 ->
+            case 0xcc74da30 ->
                 name.equalsString(NAME_RUNTIME_INVISIBLE_PARAMETER_ANNOTATIONS) ? runtimeInvisibleParameterAnnotations() : null;
-            case 0x5299824 ->
+            case 0xf67697f5 ->
                 name.equalsString(NAME_RUNTIME_INVISIBLE_TYPE_ANNOTATIONS) ? runtimeInvisibleTypeAnnotations() : null;
-            case 0x3534786e ->
+            case 0xe0837d2a ->
                 name.equalsString(NAME_RUNTIME_VISIBLE_ANNOTATIONS) ? runtimeVisibleAnnotations() : null;
-            case 0xb4b4ac6 ->
+            case 0xc945a075 ->
                 name.equalsString(NAME_RUNTIME_VISIBLE_PARAMETER_ANNOTATIONS) ? runtimeVisibleParameterAnnotations() : null;
-            case 0x6926482 ->
+            case 0x611a3a90 ->
                 name.equalsString(NAME_RUNTIME_VISIBLE_TYPE_ANNOTATIONS) ? runtimeVisibleTypeAnnotations() : null;
-            case 0x16a42b7c ->
+            case 0xf76fb898 ->
                 name.equalsString(NAME_SIGNATURE) ? signature() : null;
-            case 0x400ab245 ->
+            case 0x6b41b047 ->
                 name.equalsString(NAME_SOURCE_DEBUG_EXTENSION) ? sourceDebugExtension() : null;
-            case 0x2af490d4 ->
+            case 0x748c2857 ->
                 name.equalsString(NAME_SOURCE_FILE) ? sourceFile() : null;
-            case 0x303e0c58 ->
+            case 0x6bf13a96 ->
                 name.equalsString(NAME_SOURCE_ID) ? sourceId() : null;
-            case 0x19c7d0cd ->
+            case 0xfa85ee5a ->
                 name.equalsString(NAME_STACK_MAP_TABLE) ? stackMapTable() : null;
-            case 0x3dc79b7a ->
+            case 0xf2670725 ->
                 name.equalsString(NAME_SYNTHETIC) ? synthetic() : null;
             default -> null;
         };

src/java.base/share/classes/jdk/internal/classfile/impl/BufferedCodeBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 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
@@ -43,7 +43,7 @@ import java.util.Optional;
 import java.util.function.Consumer;
 
 public final class BufferedCodeBuilder
-        implements TerminalCodeBuilder, LabelContext {
+        implements TerminalCodeBuilder {
     private final SplitConstantPool constantPool;
     private final ClassFileImpl context;
     private final List<CodeElement> elements = new ArrayList<>();