8346567: Make Class.getModifiers() non-native

src/hotspot/share/c1/c1_Canonicalizer.cpp

@@ -547,22 +547,6 @@ void Canonicalizer::do_Intrinsic      (Intrinsic*       x) {
     }
     break;
   }
-  case vmIntrinsics::_getModifiers: {
-    assert(x->number_of_arguments() == 1, "wrong type");
-
-    // Optimize for Foo.class.getModifier()
-    InstanceConstant* c = x->argument_at(0)->type()->as_InstanceConstant();
-    if (c != nullptr && !c->value()->is_null_object()) {
-      ciType* t = c->value()->java_mirror_type();
-      if (t->is_klass()) {
-        set_constant(t->as_klass()->modifier_flags());
-      } else {
-        assert(t->is_primitive_type(), "should be a primitive type");
-        set_constant(JVM_ACC_ABSTRACT | JVM_ACC_FINAL | JVM_ACC_PUBLIC);
-      }
-    }
-    break;
-  }
   default:
     break;
   }

src/hotspot/share/c1/c1_Compiler.cpp

@@ -156,7 +156,6 @@ bool Compiler::is_intrinsic_supported(vmIntrinsics::ID id) {
   case vmIntrinsics::_getClass:
   case vmIntrinsics::_isInstance:
   case vmIntrinsics::_isPrimitive:
-  case vmIntrinsics::_getModifiers:
   case vmIntrinsics::_currentCarrierThread:
   case vmIntrinsics::_currentThread:
   case vmIntrinsics::_scopedValueCache:

src/hotspot/share/c1/c1_LIRGenerator.cpp

@@ -1303,42 +1303,6 @@ void LIRGenerator::do_isPrimitive(Intrinsic* x) {
   __ cmove(lir_cond_notEqual, LIR_OprFact::intConst(0), LIR_OprFact::intConst(1), result, T_BOOLEAN);
 }
 
-// Example: Foo.class.getModifiers()
-void LIRGenerator::do_getModifiers(Intrinsic* x) {
-  assert(x->number_of_arguments() == 1, "wrong type");
-
-  LIRItem receiver(x->argument_at(0), this);
-  receiver.load_item();
-  LIR_Opr result = rlock_result(x);
-
-  CodeEmitInfo* info = nullptr;
-  if (x->needs_null_check()) {
-    info = state_for(x);
-  }
-
-  // While reading off the universal constant mirror is less efficient than doing
-  // another branch and returning the constant answer, this branchless code runs into
-  // much less risk of confusion for C1 register allocator. The choice of the universe
-  // object here is correct as long as it returns the same modifiers we would expect
-  // from the primitive class itself. See spec for Class.getModifiers that provides
-  // the typed array klasses with similar modifiers as their component types.
-
-  Klass* univ_klass = Universe::byteArrayKlass();
-  assert(univ_klass->modifier_flags() == (JVM_ACC_ABSTRACT | JVM_ACC_FINAL | JVM_ACC_PUBLIC), "Sanity");
-  LIR_Opr prim_klass = LIR_OprFact::metadataConst(univ_klass);
-
-  LIR_Opr recv_klass = new_register(T_METADATA);
-  __ move(new LIR_Address(receiver.result(), java_lang_Class::klass_offset(), T_ADDRESS), recv_klass, info);
-
-  // Check if this is a Java mirror of primitive type, and select the appropriate klass.
-  LIR_Opr klass = new_register(T_METADATA);
-  __ cmp(lir_cond_equal, recv_klass, LIR_OprFact::metadataConst(nullptr));
-  __ cmove(lir_cond_equal, prim_klass, recv_klass, klass, T_ADDRESS);
-
-  // Get the answer.
-  __ move(new LIR_Address(klass, in_bytes(Klass::modifier_flags_offset()), T_CHAR), result);
-}
-
 void LIRGenerator::do_getObjectSize(Intrinsic* x) {
   assert(x->number_of_arguments() == 3, "wrong type");
   LIR_Opr result_reg = rlock_result(x);
@@ -2957,7 +2921,6 @@ void LIRGenerator::do_Intrinsic(Intrinsic* x) {
   case vmIntrinsics::_Object_init:    do_RegisterFinalizer(x); break;
   case vmIntrinsics::_isInstance:     do_isInstance(x);    break;
   case vmIntrinsics::_isPrimitive:    do_isPrimitive(x);   break;
-  case vmIntrinsics::_getModifiers:   do_getModifiers(x);  break;
   case vmIntrinsics::_getClass:       do_getClass(x);      break;
   case vmIntrinsics::_getObjectSize:  do_getObjectSize(x); break;
   case vmIntrinsics::_currentCarrierThread: do_currentCarrierThread(x); break;

src/hotspot/share/c1/c1_LIRGenerator.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -255,7 +255,6 @@ class LIRGenerator: public InstructionVisitor, public BlockClosure {
   void do_RegisterFinalizer(Intrinsic* x);
   void do_isInstance(Intrinsic* x);
   void do_isPrimitive(Intrinsic* x);
-  void do_getModifiers(Intrinsic* x);
   void do_getClass(Intrinsic* x);
   void do_getObjectSize(Intrinsic* x);
   void do_currentCarrierThread(Intrinsic* x);

src/hotspot/share/ci/ciKlass.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -122,7 +122,7 @@ class ciKlass : public ciType {
   // Get the instance of java.lang.Class corresponding to this klass.
   ciInstance*            java_mirror();
 
-  // Fetch Klass::modifier_flags.
+  // Fetch modifier flags.
   jint                   modifier_flags();
 
   // Fetch Klass::access_flags.

src/hotspot/share/classfile/classFileParser.cpp

@@ -3747,11 +3747,6 @@ void ClassFileParser::apply_parsed_class_metadata(
   this_klass->set_permitted_subclasses(_permitted_subclasses);
   this_klass->set_record_components(_record_components);
 
-  // Initialize cached modifier_flags to support Class.getModifiers().
-  // This must follow setting inner_class attributes.
-  u2 computed_modifiers = this_klass->compute_modifier_flags();
-  this_klass->set_modifier_flags(computed_modifiers);
-
   // Delay the setting of _local_interfaces and _transitive_interfaces until after
   // initialize_supers() in fill_instance_klass(). It is because the _local_interfaces could
   // be shared with _transitive_interfaces and _transitive_interfaces may be shared with

src/hotspot/share/classfile/javaClasses.cpp

@@ -867,6 +867,7 @@ int java_lang_Class::_source_file_offset;
 int java_lang_Class::_classData_offset;
 int java_lang_Class::_classRedefinedCount_offset;
 int java_lang_Class::_reflectionData_offset;
+int java_lang_Class::_modifiers_offset;
 
 bool java_lang_Class::_offsets_computed = false;
 GrowableArray<Klass*>* java_lang_Class::_fixup_mirror_list = nullptr;
@@ -1060,6 +1061,10 @@ void java_lang_Class::allocate_mirror(Klass* k, bool is_scratch, Handle protecti
   // Setup indirection from mirror->klass
   set_klass(mirror(), k);
 
+  // Set the modifiers flag.
+  int computed_modifiers = k->compute_modifier_flags();
+  set_modifiers(mirror(), computed_modifiers);
+
   InstanceMirrorKlass* mk = InstanceMirrorKlass::cast(mirror->klass());
   assert(oop_size(mirror()) == mk->instance_size(k), "should have been set");
 
@@ -1355,6 +1360,7 @@ oop java_lang_Class::create_basic_type_mirror(const char* basic_type_name, Basic
   InstanceMirrorKlass* mk = InstanceMirrorKlass::cast(vmClasses::Class_klass());
   assert(static_oop_field_count(java_class) == 0, "should have been zeroed by allocation");
 #endif
+  set_modifiers(java_class, JVM_ACC_ABSTRACT | JVM_ACC_FINAL | JVM_ACC_PUBLIC);
   return java_class;
 }
 
@@ -1493,7 +1499,8 @@ oop java_lang_Class::primitive_mirror(BasicType t) {
   macro(_name_offset,                k, "name",                string_signature,       false); \
   macro(_classData_offset,           k, "classData",           object_signature,       false); \
   macro(_reflectionData_offset,      k, "reflectionData",      java_lang_ref_SoftReference_signature, false); \
-  macro(_signers_offset,             k, "signers",             object_array_signature, false);
+  macro(_signers_offset,             k, "signers",             object_array_signature, false); \
+  macro(_modifiers_offset,           k, vmSymbols::modifiers_name(), int_signature,    false);
 
 void java_lang_Class::compute_offsets() {
   if (_offsets_computed) {
@@ -1527,6 +1534,16 @@ void java_lang_Class::set_classRedefinedCount(oop the_class_mirror, int value) {
   the_class_mirror->int_field_put(_classRedefinedCount_offset, value);
 }
 
+int java_lang_Class::modifiers(oop the_class_mirror) {
+  assert(_modifiers_offset != 0, "offsets should have been initialized");
+  return the_class_mirror->int_field(_modifiers_offset);
+}
+
+void java_lang_Class::set_modifiers(oop the_class_mirror, int value) {
+  assert(_modifiers_offset != 0, "offsets should have been initialized");
+  the_class_mirror->int_field_put(_modifiers_offset, value);
+}
+
 
 // Note: JDK1.1 and before had a privateInfo_offset field which was used for the
 //       platform thread structure, and a eetop offset which was used for thread

src/hotspot/share/classfile/javaClasses.hpp

@@ -257,6 +257,7 @@ class java_lang_Class : AllStatic {
   static int _classData_offset;
   static int _classRedefinedCount_offset;
   static int _reflectionData_offset;
+  static int _modifiers_offset;
 
   static bool _offsets_computed;
 
@@ -337,6 +338,9 @@ class java_lang_Class : AllStatic {
   static oop source_file(oop java_class);
   static void set_source_file(oop java_class, oop source_file);
 
+  static int modifiers(oop java_class);
+  static void set_modifiers(oop java_class, int value);
+
   static size_t oop_size(oop java_class);
   static void set_oop_size(HeapWord* java_class, size_t size);
   static int static_oop_field_count(oop java_class);

src/hotspot/share/classfile/vmIntrinsics.cpp

@@ -256,7 +256,6 @@ bool vmIntrinsics::disabled_by_jvm_flags(vmIntrinsics::ID id) {
   switch (id) {
   case vmIntrinsics::_isInstance:
   case vmIntrinsics::_isAssignableFrom:
-  case vmIntrinsics::_getModifiers:
   case vmIntrinsics::_isInterface:
   case vmIntrinsics::_isArray:
   case vmIntrinsics::_isPrimitive:

src/hotspot/share/classfile/vmIntrinsics.hpp

@@ -304,8 +304,6 @@ class methodHandle;
    do_name(     isAssignableFrom_name,                           "isAssignableFrom")                                    \
   do_intrinsic(_isInstance,               java_lang_Class,        isInstance_name, object_boolean_signature,     F_RN)  \
    do_name(     isInstance_name,                                 "isInstance")                                          \
-  do_intrinsic(_getModifiers,             java_lang_Class,        getModifiers_name, void_int_signature,         F_RN)  \
-   do_name(     getModifiers_name,                               "getModifiers")                                        \
   do_intrinsic(_isInterface,              java_lang_Class,        isInterface_name, void_boolean_signature,      F_RN)  \
    do_name(     isInterface_name,                                "isInterface")                                         \
   do_intrinsic(_isArray,                  java_lang_Class,        isArray_name, void_boolean_signature,          F_RN)  \

src/hotspot/share/jvmci/vmStructs_jvmci.cpp

@@ -272,7 +272,6 @@
   nonstatic_field(Klass,                       _name,                                         Symbol*)                               \
   volatile_nonstatic_field(Klass,              _next_sibling,                                 Klass*)                                \
   nonstatic_field(Klass,                       _java_mirror,                                  OopHandle)                             \
-  nonstatic_field(Klass,                       _modifier_flags,                               u2)                                    \
   nonstatic_field(Klass,                       _access_flags,                                 AccessFlags)                           \
   nonstatic_field(Klass,                       _class_loader_data,                            ClassLoaderData*)                      \
   nonstatic_field(Klass,                       _secondary_supers_bitmap,                      uintx)                                 \

src/hotspot/share/oops/klass.cpp

@@ -328,6 +328,12 @@ jint Klass::array_layout_helper(BasicType etype) {
   return lh;
 }
 
+int Klass::modifier_flags() const {
+  int mods = java_lang_Class::modifiers(java_mirror());
+  assert(mods == compute_modifier_flags(), "should be same");
+  return mods;
+}
+
 bool Klass::can_be_primary_super_slow() const {
   if (super() == nullptr)
     return true;

src/hotspot/share/oops/klass.hpp

@@ -123,9 +123,6 @@ class Klass : public Metadata {
   AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.
                                 // Some flags created by the JVM, not in the class file itself,
                                 // are in _misc_flags below.
-  // Processed access flags, for use by Class.getModifiers.
-  u2          _modifier_flags;
-
   KlassFlags  _misc_flags;
 
   // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
@@ -292,10 +289,6 @@ class Klass : public Metadata {
   // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
   void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
 
-  // modifier flags
-  u2 modifier_flags() const          { return _modifier_flags; }
-  void set_modifier_flags(u2 flags)  { _modifier_flags = flags; }
-
   // size helper
   int layout_helper() const            { return _layout_helper; }
   void set_layout_helper(int lh)       { _layout_helper = lh; }
@@ -448,7 +441,6 @@ class Klass : public Metadata {
   static ByteSize secondary_supers_offset()      { return byte_offset_of(Klass, _secondary_supers); }
   static ByteSize java_mirror_offset()           { return byte_offset_of(Klass, _java_mirror); }
   static ByteSize class_loader_data_offset()     { return byte_offset_of(Klass, _class_loader_data); }
-  static ByteSize modifier_flags_offset()        { return byte_offset_of(Klass, _modifier_flags); }
   static ByteSize layout_helper_offset()         { return byte_offset_of(Klass, _layout_helper); }
   static ByteSize access_flags_offset()          { return byte_offset_of(Klass, _access_flags); }
 #if INCLUDE_JVMCI
@@ -758,6 +750,7 @@ class Klass : public Metadata {
 
  public:
   virtual u2 compute_modifier_flags() const = 0;
+  int modifier_flags() const;
 
   // JVMTI support
   virtual jint jvmti_class_status() const;

src/hotspot/share/oops/objArrayKlass.cpp

@@ -139,9 +139,6 @@ ObjArrayKlass::ObjArrayKlass(int n, Klass* element_klass, Symbol* name) : ArrayK
   set_layout_helper(array_layout_helper(T_OBJECT));
   assert(is_array_klass(), "sanity");
   assert(is_objArray_klass(), "sanity");
-
-  // Compute modifier flags after bottom_klass and element_klass are initialized.
-  set_modifier_flags(compute_modifier_flags());
 }
 
 size_t ObjArrayKlass::oop_size(oop obj) const {

src/hotspot/share/oops/typeArrayKlass.cpp

@@ -87,9 +87,6 @@ TypeArrayKlass::TypeArrayKlass(BasicType type, Symbol* name) : ArrayKlass(name,
   assert(size() >= TypeArrayKlass::header_size(), "bad size");
 
   set_class_loader_data(ClassLoaderData::the_null_class_loader_data());
-
-  // Compute modifier flags.
-  set_modifier_flags(compute_modifier_flags());
 }
 
 typeArrayOop TypeArrayKlass::allocate_common(int length, bool do_zero, TRAPS) {

src/hotspot/share/oops/typeArrayKlass.hpp

@@ -51,6 +51,8 @@ class TypeArrayKlass : public ArrayKlass {
   jint max_length()                     { return _max_length; }
   void set_max_length(jint m)           { _max_length = m;    }
 
+  u2 compute_modifier_flags() const;
+
   // testers
   DEBUG_ONLY(bool is_typeArray_klass_slow() const  { return true; })
 
@@ -73,8 +75,6 @@ class TypeArrayKlass : public ArrayKlass {
   // Copying
   void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
 
-  u2 compute_modifier_flags() const;
-
   // Oop iterators. Since there are no oops in TypeArrayKlasses,
   // these functions only return the size of the object.
 

src/hotspot/share/opto/c2compiler.cpp

@@ -749,7 +749,6 @@ bool C2Compiler::is_intrinsic_supported(vmIntrinsics::ID id) {
   case vmIntrinsics::_clone:
   case vmIntrinsics::_isAssignableFrom:
   case vmIntrinsics::_isInstance:
-  case vmIntrinsics::_getModifiers:
   case vmIntrinsics::_isInterface:
   case vmIntrinsics::_isArray:
   case vmIntrinsics::_isPrimitive:

src/hotspot/share/opto/compile.cpp

@@ -1699,8 +1699,6 @@ Compile::AliasType* Compile::find_alias_type(const TypePtr* adr_type, bool no_cr
       }
       if (flat->offset() == in_bytes(Klass::super_check_offset_offset()))
         alias_type(idx)->set_rewritable(false);
-      if (flat->offset() == in_bytes(Klass::modifier_flags_offset()))
-        alias_type(idx)->set_rewritable(false);
       if (flat->offset() == in_bytes(Klass::access_flags_offset()))
         alias_type(idx)->set_rewritable(false);
       if (flat->offset() == in_bytes(Klass::misc_flags_offset()))

src/hotspot/share/opto/library_call.cpp

@@ -515,7 +515,6 @@ bool LibraryCallKit::try_to_inline(int predicate) {
   case vmIntrinsics::_isAssignableFrom:         return inline_native_subtype_check();
 
   case vmIntrinsics::_isInstance:
-  case vmIntrinsics::_getModifiers:
   case vmIntrinsics::_isInterface:
   case vmIntrinsics::_isArray:
   case vmIntrinsics::_isPrimitive:
@@ -3891,10 +3890,6 @@ bool LibraryCallKit::inline_native_Class_query(vmIntrinsics::ID id) {
     prim_return_value = intcon(0);
     obj = argument(1);
     break;
-  case vmIntrinsics::_getModifiers:
-    prim_return_value = intcon(JVM_ACC_ABSTRACT | JVM_ACC_FINAL | JVM_ACC_PUBLIC);
-    return_type = TypeInt::CHAR;
-    break;
   case vmIntrinsics::_isInterface:
     prim_return_value = intcon(0);
     break;
@@ -3974,11 +3969,6 @@ bool LibraryCallKit::inline_native_Class_query(vmIntrinsics::ID id) {
     query_value = gen_instanceof(obj, kls, safe_for_replace);
     break;
 
-  case vmIntrinsics::_getModifiers:
-    p = basic_plus_adr(kls, in_bytes(Klass::modifier_flags_offset()));
-    query_value = make_load(nullptr, p, TypeInt::CHAR, T_CHAR, MemNode::unordered);
-    break;
-
   case vmIntrinsics::_isInterface:
     // (To verify this code sequence, check the asserts in JVM_IsInterface.)
     if (generate_interface_guard(kls, region) != nullptr)

src/hotspot/share/opto/memnode.cpp

@@ -1972,12 +1972,6 @@ LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
                                  ciKlass* klass) const {
   assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
          "must not happen");
-  if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
-    // The field is Klass::_modifier_flags.  Return its (constant) value.
-    // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
-    assert(Opcode() == Op_LoadUS, "must load an unsigned short from _modifier_flags");
-    return TypeInt::make(klass->modifier_flags());
-  }
   if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
     // The field is Klass::_access_flags.  Return its (constant) value.
     // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
@@ -2461,7 +2455,7 @@ const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
           // a primitive Class (e.g., int.class) has null for a klass field
           return TypePtr::NULL_PTR;
         }
-        // (Folds up the 1st indirection in aClassConstant.getModifiers().)
+        // Fold up the load of the hidden field
         return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
       }
       // non-constant mirror, so we can't tell what's going on