1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_VM_CLASSFILE_SYSTEMDICTIONARY_HPP
  26 #define SHARE_VM_CLASSFILE_SYSTEMDICTIONARY_HPP
  27 
  28 #include "classfile/classLoader.hpp"
  29 #include "jvmci/systemDictionary_jvmci.hpp"
  30 #include "oops/objArrayOop.hpp"
  31 #include "oops/symbol.hpp"
  32 #include "runtime/java.hpp"
  33 #include "runtime/reflectionUtils.hpp"
  34 #include "runtime/signature.hpp"
  35 #include "utilities/hashtable.hpp"
  36 
  37 // The dictionary in each ClassLoaderData stores all loaded classes, either
  38 // initiatied by its class loader or defined by its class loader:
  39 //
  40 //   class loader -> ClassLoaderData -> [class, protection domain set]
  41 //
  42 // Classes are loaded lazily. The default VM class loader is
  43 // represented as NULL.
  44 
  45 // The underlying data structure is an open hash table (Dictionary) per
  46 // ClassLoaderData with a fixed number of buckets. During loading the
  47 // class loader object is locked, (for the VM loader a private lock object is used).
  48 // The global SystemDictionary_lock is held for all additions into the ClassLoaderData
  49 // dictionaries.  TODO: fix lock granularity so that class loading can
  50 // be done concurrently, but only by different loaders.
  51 //
  52 // During loading a placeholder (name, loader) is temporarily placed in
  53 // a side data structure, and is used to detect ClassCircularityErrors
  54 // and to perform verification during GC.  A GC can occur in the midst
  55 // of class loading, as we call out to Java, have to take locks, etc.
  56 //
  57 // When class loading is finished, a new entry is added to the dictionary
  58 // of the class loader and the placeholder is removed. Note that the protection
  59 // domain field of the dictionary entry has not yet been filled in when
  60 // the "real" dictionary entry is created.
  61 //
  62 // Clients of this class who are interested in finding if a class has
  63 // been completely loaded -- not classes in the process of being loaded --
  64 // can read the dictionary unlocked. This is safe because
  65 //    - entries are only deleted at safepoints
  66 //    - readers cannot come to a safepoint while actively examining
  67 //         an entry  (an entry cannot be deleted from under a reader)
  68 //    - entries must be fully formed before they are available to concurrent
  69 //         readers (we must ensure write ordering)
  70 //
  71 // Note that placeholders are deleted at any time, as they are removed
  72 // when a class is completely loaded. Therefore, readers as well as writers
  73 // of placeholders must hold the SystemDictionary_lock.
  74 //
  75 
  76 class ClassFileStream;
  77 class Dictionary;
  78 class PlaceholderTable;
  79 class LoaderConstraintTable;
  80 template <MEMFLAGS F> class HashtableBucket;
  81 class ResolutionErrorTable;
  82 class SymbolPropertyTable;
  83 class ProtectionDomainCacheTable;
  84 class ProtectionDomainCacheEntry;
  85 class GCTimer;
  86 class OopStorage;
  87 
  88 // Certain classes, such as java.lang.Object and java.lang.String,
  89 // are all "well-known", in the sense that no class loader is allowed
  90 // to provide a different definition.
  91 //
  92 // These klasses must all have names defined in vmSymbols. They are
  93 // resolved during early VM start-up in a specific order.
  94 
  95 #define WK_KLASS_ENUM_NAME(kname)    kname##_knum
  96 
  97 // Each well-known class has a short klass name (like object_klass),
  98 // and a vmSymbol name (like java_lang_Object).
  99 // The order of these definitions is significant; it is the order in which
 100 // class resolution is actually performed by resolve_well_known_classes.
 101 
 102 #define WK_KLASSES_DO(do_klass)                                                                                 \
 103   /* well-known classes */                                                                                      \
 104   do_klass(Object_klass,                                java_lang_Object                                      ) \
 105   do_klass(String_klass,                                java_lang_String                                      ) \
 106   do_klass(Class_klass,                                 java_lang_Class                                       ) \
 107   do_klass(Cloneable_klass,                             java_lang_Cloneable                                   ) \
 108   do_klass(ClassLoader_klass,                           java_lang_ClassLoader                                 ) \
 109   do_klass(Serializable_klass,                          java_io_Serializable                                  ) \
 110   do_klass(System_klass,                                java_lang_System                                      ) \
 111   do_klass(Throwable_klass,                             java_lang_Throwable                                   ) \
 112   do_klass(Error_klass,                                 java_lang_Error                                       ) \
 113   do_klass(ThreadDeath_klass,                           java_lang_ThreadDeath                                 ) \
 114   do_klass(Exception_klass,                             java_lang_Exception                                   ) \
 115   do_klass(RuntimeException_klass,                      java_lang_RuntimeException                            ) \
 116   do_klass(SecurityManager_klass,                       java_lang_SecurityManager                             ) \
 117   do_klass(ProtectionDomain_klass,                      java_security_ProtectionDomain                        ) \
 118   do_klass(AccessControlContext_klass,                  java_security_AccessControlContext                    ) \
 119   do_klass(SecureClassLoader_klass,                     java_security_SecureClassLoader                       ) \
 120   do_klass(ClassNotFoundException_klass,                java_lang_ClassNotFoundException                      ) \
 121   do_klass(NoClassDefFoundError_klass,                  java_lang_NoClassDefFoundError                        ) \
 122   do_klass(LinkageError_klass,                          java_lang_LinkageError                                ) \
 123   do_klass(ClassCastException_klass,                    java_lang_ClassCastException                          ) \
 124   do_klass(ArrayStoreException_klass,                   java_lang_ArrayStoreException                         ) \
 125   do_klass(VirtualMachineError_klass,                   java_lang_VirtualMachineError                         ) \
 126   do_klass(OutOfMemoryError_klass,                      java_lang_OutOfMemoryError                            ) \
 127   do_klass(StackOverflowError_klass,                    java_lang_StackOverflowError                          ) \
 128   do_klass(IllegalMonitorStateException_klass,          java_lang_IllegalMonitorStateException                ) \
 129   do_klass(Reference_klass,                             java_lang_ref_Reference                               ) \
 130                                                                                                                 \
 131   /* ref klasses and set reference types */                                                                     \
 132   do_klass(SoftReference_klass,                         java_lang_ref_SoftReference                           ) \
 133   do_klass(WeakReference_klass,                         java_lang_ref_WeakReference                           ) \
 134   do_klass(FinalReference_klass,                        java_lang_ref_FinalReference                          ) \
 135   do_klass(PhantomReference_klass,                      java_lang_ref_PhantomReference                        ) \
 136   do_klass(Finalizer_klass,                             java_lang_ref_Finalizer                               ) \
 137                                                                                                                 \
 138   do_klass(Thread_klass,                                java_lang_Thread                                      ) \
 139   do_klass(ThreadGroup_klass,                           java_lang_ThreadGroup                                 ) \
 140   do_klass(Properties_klass,                            java_util_Properties                                  ) \
 141   do_klass(Module_klass,                                java_lang_Module                                      ) \
 142   do_klass(reflect_AccessibleObject_klass,              java_lang_reflect_AccessibleObject                    ) \
 143   do_klass(reflect_Field_klass,                         java_lang_reflect_Field                               ) \
 144   do_klass(reflect_Parameter_klass,                     java_lang_reflect_Parameter                           ) \
 145   do_klass(reflect_Method_klass,                        java_lang_reflect_Method                              ) \
 146   do_klass(reflect_Constructor_klass,                   java_lang_reflect_Constructor                         ) \
 147                                                                                                                 \
 148   /* NOTE: needed too early in bootstrapping process to have checks based on JDK version */                     \
 149   /* It's okay if this turns out to be NULL in non-1.4 JDKs. */                                                 \
 150   do_klass(reflect_MagicAccessorImpl_klass,             reflect_MagicAccessorImpl                             ) \
 151   do_klass(reflect_MethodAccessorImpl_klass,            reflect_MethodAccessorImpl                            ) \
 152   do_klass(reflect_ConstructorAccessorImpl_klass,       reflect_ConstructorAccessorImpl                       ) \
 153   do_klass(reflect_DelegatingClassLoader_klass,         reflect_DelegatingClassLoader                         ) \
 154   do_klass(reflect_ConstantPool_klass,                  reflect_ConstantPool                                  ) \
 155   do_klass(reflect_UnsafeStaticFieldAccessorImpl_klass, reflect_UnsafeStaticFieldAccessorImpl                 ) \
 156   do_klass(reflect_CallerSensitive_klass,               reflect_CallerSensitive                               ) \
 157                                                                                                                 \
 158   /* support for dynamic typing; it's OK if these are NULL in earlier JDKs */                                   \
 159   do_klass(DirectMethodHandle_klass,                    java_lang_invoke_DirectMethodHandle                   ) \
 160   do_klass(MethodHandle_klass,                          java_lang_invoke_MethodHandle                         ) \
 161   do_klass(VarHandle_klass,                             java_lang_invoke_VarHandle                            ) \
 162   do_klass(MemberName_klass,                            java_lang_invoke_MemberName                           ) \
 163   do_klass(ResolvedMethodName_klass,                    java_lang_invoke_ResolvedMethodName                   ) \
 164   do_klass(MethodHandleNatives_klass,                   java_lang_invoke_MethodHandleNatives                  ) \
 165   do_klass(LambdaForm_klass,                            java_lang_invoke_LambdaForm                           ) \
 166   do_klass(MethodType_klass,                            java_lang_invoke_MethodType                           ) \
 167   do_klass(BootstrapMethodError_klass,                  java_lang_BootstrapMethodError                        ) \
 168   do_klass(CallSite_klass,                              java_lang_invoke_CallSite                             ) \
 169   do_klass(Context_klass,                               java_lang_invoke_MethodHandleNatives_CallSiteContext  ) \
 170   do_klass(ConstantCallSite_klass,                      java_lang_invoke_ConstantCallSite                     ) \
 171   do_klass(MutableCallSite_klass,                       java_lang_invoke_MutableCallSite                      ) \
 172   do_klass(VolatileCallSite_klass,                      java_lang_invoke_VolatileCallSite                     ) \
 173   /* Note: MethodHandle must be first, and VolatileCallSite last in group */                                    \
 174                                                                                                                 \
 175   do_klass(AssertionStatusDirectives_klass,             java_lang_AssertionStatusDirectives                   ) \
 176   do_klass(StringBuffer_klass,                          java_lang_StringBuffer                                ) \
 177   do_klass(StringBuilder_klass,                         java_lang_StringBuilder                               ) \
 178   do_klass(internal_Unsafe_klass,                       jdk_internal_misc_Unsafe                              ) \
 179   do_klass(module_Modules_klass,                        jdk_internal_module_Modules                           ) \
 180                                                                                                                 \
 181   /* support for CDS */                                                                                         \
 182   do_klass(ByteArrayInputStream_klass,                  java_io_ByteArrayInputStream                          ) \
 183   do_klass(URL_klass,                                   java_net_URL                                          ) \
 184   do_klass(Jar_Manifest_klass,                          java_util_jar_Manifest                                ) \
 185   do_klass(jdk_internal_loader_ClassLoaders_klass,      jdk_internal_loader_ClassLoaders                      ) \
 186   do_klass(jdk_internal_loader_ClassLoaders_AppClassLoader_klass,      jdk_internal_loader_ClassLoaders_AppClassLoader) \
 187   do_klass(jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass, jdk_internal_loader_ClassLoaders_PlatformClassLoader) \
 188   do_klass(CodeSource_klass,                            java_security_CodeSource                              ) \
 189                                                                                                                 \
 190   do_klass(StackTraceElement_klass,                     java_lang_StackTraceElement                           ) \
 191                                                                                                                 \
 192   /* It's okay if this turns out to be NULL in non-1.4 JDKs. */                                                 \
 193   do_klass(nio_Buffer_klass,                            java_nio_Buffer                                       ) \
 194                                                                                                                 \
 195   /* Stack Walking */                                                                                           \
 196   do_klass(StackWalker_klass,                           java_lang_StackWalker                                 ) \
 197   do_klass(AbstractStackWalker_klass,                   java_lang_StackStreamFactory_AbstractStackWalker      ) \
 198   do_klass(StackFrameInfo_klass,                        java_lang_StackFrameInfo                              ) \
 199   do_klass(LiveStackFrameInfo_klass,                    java_lang_LiveStackFrameInfo                          ) \
 200                                                                                                                 \
 201   /* support for stack dump lock analysis */                                                                    \
 202   do_klass(java_util_concurrent_locks_AbstractOwnableSynchronizer_klass, java_util_concurrent_locks_AbstractOwnableSynchronizer) \
 203                                                                                                                 \
 204   /* boxing klasses */                                                                                          \
 205   do_klass(Boolean_klass,                               java_lang_Boolean                                     ) \
 206   do_klass(Character_klass,                             java_lang_Character                                   ) \
 207   do_klass(Float_klass,                                 java_lang_Float                                       ) \
 208   do_klass(Double_klass,                                java_lang_Double                                      ) \
 209   do_klass(Byte_klass,                                  java_lang_Byte                                        ) \
 210   do_klass(Short_klass,                                 java_lang_Short                                       ) \
 211   do_klass(Integer_klass,                               java_lang_Integer                                     ) \
 212   do_klass(Long_klass,                                  java_lang_Long                                        ) \
 213                                                                                                                 \
 214   /* JVMCI classes. These are loaded on-demand. */                                                              \
 215   JVMCI_WK_KLASSES_DO(do_klass)                                                                                 \
 216                                                                                                                 \
 217   /*end*/
 218 
 219 
 220 class SystemDictionary : AllStatic {
 221   friend class VMStructs;
 222   friend class SystemDictionaryHandles;
 223 
 224  public:
 225   enum WKID {
 226     NO_WKID = 0,
 227 
 228     #define WK_KLASS_ENUM(name, symbol) WK_KLASS_ENUM_NAME(name), WK_KLASS_ENUM_NAME(symbol) = WK_KLASS_ENUM_NAME(name),
 229     WK_KLASSES_DO(WK_KLASS_ENUM)
 230     #undef WK_KLASS_ENUM
 231 
 232     WKID_LIMIT,
 233 
 234 #if INCLUDE_JVMCI
 235     FIRST_JVMCI_WKID = WK_KLASS_ENUM_NAME(JVMCI_klass),
 236     LAST_JVMCI_WKID  = WK_KLASS_ENUM_NAME(Value_klass),
 237 #endif
 238 
 239     FIRST_WKID = NO_WKID + 1
 240   };
 241 
 242   // Returns a class with a given class name and class loader.  Loads the
 243   // class if needed. If not found a NoClassDefFoundError or a
 244   // ClassNotFoundException is thrown, depending on the value on the
 245   // throw_error flag.  For most uses the throw_error argument should be set
 246   // to true.
 247 
 248   static Klass* resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS);
 249   // Convenient call for null loader and protection domain.
 250   static Klass* resolve_or_fail(Symbol* class_name, bool throw_error, TRAPS);
 251 protected:
 252   // handle error translation for resolve_or_null results
 253   static Klass* handle_resolution_exception(Symbol* class_name, bool throw_error, Klass* klass, TRAPS);
 254 
 255 public:
 256 
 257   // Returns a class with a given class name and class loader.
 258   // Loads the class if needed. If not found NULL is returned.
 259   static Klass* resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);
 260   // Version with null loader and protection domain
 261   static Klass* resolve_or_null(Symbol* class_name, TRAPS);
 262 
 263   // Resolve a superclass or superinterface. Called from ClassFileParser,
 264   // parse_interfaces, resolve_instance_class_or_null, load_shared_class
 265   // "child_name" is the class whose super class or interface is being resolved.
 266   static InstanceKlass* resolve_super_or_fail(Symbol* child_name,
 267                                               Symbol* class_name,
 268                                               Handle class_loader,
 269                                               Handle protection_domain,
 270                                               bool is_superclass,
 271                                               TRAPS);
 272 
 273   // Parse new stream. This won't update the dictionary or
 274   // class hierarchy, simply parse the stream. Used by JVMTI RedefineClasses.
 275   // Also used by Unsafe_DefineAnonymousClass
 276   static InstanceKlass* parse_stream(Symbol* class_name,
 277                                      Handle class_loader,
 278                                      Handle protection_domain,
 279                                      ClassFileStream* st,
 280                                      TRAPS) {
 281     return parse_stream(class_name,
 282                         class_loader,
 283                         protection_domain,
 284                         st,
 285                         NULL, // unsafe_anonymous_host
 286                         NULL, // cp_patches
 287                         THREAD);
 288   }
 289   static InstanceKlass* parse_stream(Symbol* class_name,
 290                                      Handle class_loader,
 291                                      Handle protection_domain,
 292                                      ClassFileStream* st,
 293                                      const InstanceKlass* unsafe_anonymous_host,
 294                                      GrowableArray<Handle>* cp_patches,
 295                                      TRAPS);
 296 
 297   // Resolve from stream (called by jni_DefineClass and JVM_DefineClass)
 298   static InstanceKlass* resolve_from_stream(Symbol* class_name,
 299                                             Handle class_loader,
 300                                             Handle protection_domain,
 301                                             ClassFileStream* st,
 302                                             TRAPS);
 303 
 304   // Lookup an already loaded class. If not found NULL is returned.
 305   static Klass* find(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);
 306 
 307   // Lookup an already loaded instance or array class.
 308   // Do not make any queries to class loaders; consult only the cache.
 309   // If not found NULL is returned.
 310   static Klass* find_instance_or_array_klass(Symbol* class_name,
 311                                                Handle class_loader,
 312                                                Handle protection_domain,
 313                                                TRAPS);
 314 
 315   // Lookup an instance or array class that has already been loaded
 316   // either into the given class loader, or else into another class
 317   // loader that is constrained (via loader constraints) to produce
 318   // a consistent class.  Do not take protection domains into account.
 319   // Do not make any queries to class loaders; consult only the cache.
 320   // Return NULL if the class is not found.
 321   //
 322   // This function is a strict superset of find_instance_or_array_klass.
 323   // This function (the unchecked version) makes a conservative prediction
 324   // of the result of the checked version, assuming successful lookup.
 325   // If both functions return non-null, they must return the same value.
 326   // Also, the unchecked version may sometimes be non-null where the
 327   // checked version is null.  This can occur in several ways:
 328   //   1. No query has yet been made to the class loader.
 329   //   2. The class loader was queried, but chose not to delegate.
 330   //   3. ClassLoader.checkPackageAccess rejected a proposed protection domain.
 331   //   4. Loading was attempted, but there was a linkage error of some sort.
 332   // In all of these cases, the loader constraints on this type are
 333   // satisfied, and it is safe for classes in the given class loader
 334   // to manipulate strongly-typed values of the found class, subject
 335   // to local linkage and access checks.
 336   static Klass* find_constrained_instance_or_array_klass(Symbol* class_name,
 337                                                            Handle class_loader,
 338                                                            TRAPS);
 339 
 340   static void classes_do(MetaspaceClosure* it);
 341   // Iterate over all methods in all klasses
 342 
 343   static void methods_do(void f(Method*));
 344 
 345   // Garbage collection support
 346 
 347   // Unload (that is, break root links to) all unmarked classes and
 348   // loaders.  Returns "true" iff something was unloaded.
 349   static bool do_unloading(GCTimer* gc_timer,
 350                            bool do_cleaning = true);
 351 
 352   // Used by DumpSharedSpaces only to remove classes that failed verification
 353   static void remove_classes_in_error_state();
 354 
 355   static int calculate_systemdictionary_size(int loadedclasses);
 356 
 357   // Applies "f->do_oop" to all root oops in the system dictionary.
 358   static void oops_do(OopClosure* f);
 359 
 360   // System loader lock
 361   static oop system_loader_lock()           { return _system_loader_lock_obj; }
 362 
 363   // Protection Domain Table
 364   static ProtectionDomainCacheTable* pd_cache_table() { return _pd_cache_table; }
 365 
 366 public:
 367   // Sharing support.
 368   static void reorder_dictionary_for_sharing() NOT_CDS_RETURN;
 369   static void combine_shared_dictionaries();
 370   static size_t count_bytes_for_buckets();
 371   static size_t count_bytes_for_table();
 372   static void copy_buckets(char* top, char* end);
 373   static void copy_table(char* top, char* end);
 374   static void set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
 375                                     int number_of_entries);
 376   // Printing
 377   static void print() { return print_on(tty); }
 378   static void print_on(outputStream* st);
 379   static void print_shared(outputStream* st);
 380   static void dump(outputStream* st, bool verbose);
 381 
 382   // Monotonically increasing counter which grows as classes are
 383   // loaded or modifications such as hot-swapping or setting/removing
 384   // of breakpoints are performed
 385   static inline int number_of_modifications()     { assert_locked_or_safepoint(Compile_lock); return _number_of_modifications; }
 386   // Needed by evolution and breakpoint code
 387   static inline void notice_modification()        { assert_locked_or_safepoint(Compile_lock); ++_number_of_modifications;      }
 388 
 389   // Verification
 390   static void verify();
 391 
 392   // Initialization
 393   static void initialize(TRAPS);
 394 
 395   // Checked fast access to the well-known classes -- so that you don't try to use them
 396   // before they are resolved.
 397   static InstanceKlass* check_klass(InstanceKlass* k) {
 398     assert(k != NULL, "klass not loaded");
 399     return k;
 400   }
 401 
 402   static bool resolve_wk_klass(WKID id, TRAPS);
 403   static void resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS);
 404   static void resolve_wk_klasses_through(WKID end_id, WKID &start_id, TRAPS) {
 405     int limit = (int)end_id + 1;
 406     resolve_wk_klasses_until((WKID) limit, start_id, THREAD);
 407   }
 408 
 409 public:
 410   #define WK_KLASS_DECLARE(name, symbol) \
 411     static InstanceKlass* name() { return check_klass(_well_known_klasses[WK_KLASS_ENUM_NAME(name)]); } \
 412     static InstanceKlass** name##_addr() {                                                              \
 413       return &_well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)];                          \
 414     }                                                                                                   \
 415     static bool name##_is_loaded() {                                                                    \
 416       return _well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)] != NULL;                   \
 417     }
 418   WK_KLASSES_DO(WK_KLASS_DECLARE);
 419   #undef WK_KLASS_DECLARE
 420 
 421   static InstanceKlass* well_known_klass(WKID id) {
 422     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
 423     return _well_known_klasses[id];
 424   }
 425 
 426   static InstanceKlass** well_known_klass_addr(WKID id) {
 427     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
 428     return &_well_known_klasses[id];
 429   }
 430   static void well_known_klasses_do(MetaspaceClosure* it);
 431 
 432   // Local definition for direct access to the private array:
 433   #define WK_KLASS(name) _well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)]
 434 
 435   static InstanceKlass* box_klass(BasicType t) {
 436     assert((uint)t < T_VOID+1, "range check");
 437     return check_klass(_box_klasses[t]);
 438   }
 439   static BasicType box_klass_type(Klass* k);  // inverse of box_klass
 440 #ifdef ASSERT
 441   static bool is_well_known_klass(Klass* k) {
 442     return is_well_known_klass(k->name());
 443   }
 444   static bool is_well_known_klass(Symbol* class_name);
 445 #endif
 446 
 447 protected:
 448   // Returns the class loader data to be used when looking up/updating the
 449   // system dictionary.
 450   static ClassLoaderData *class_loader_data(Handle class_loader) {
 451     return ClassLoaderData::class_loader_data(class_loader());
 452   }
 453 
 454 public:
 455   // Tells whether ClassLoader.checkPackageAccess is present
 456   static bool has_checkPackageAccess()      { return _has_checkPackageAccess; }
 457 
 458   static bool Parameter_klass_loaded()      { return WK_KLASS(reflect_Parameter_klass) != NULL; }
 459   static bool Class_klass_loaded()          { return WK_KLASS(Class_klass) != NULL; }
 460   static bool Cloneable_klass_loaded()      { return WK_KLASS(Cloneable_klass) != NULL; }
 461   static bool Object_klass_loaded()         { return WK_KLASS(Object_klass) != NULL; }
 462   static bool ClassLoader_klass_loaded()    { return WK_KLASS(ClassLoader_klass) != NULL; }
 463 
 464   // Returns java system loader
 465   static oop java_system_loader();
 466 
 467   // Returns java platform loader
 468   static oop java_platform_loader();
 469 
 470   // Compute the java system and platform loaders
 471   static void compute_java_loaders(TRAPS);
 472 
 473   // Register a new class loader
 474   static ClassLoaderData* register_loader(Handle class_loader);
 475 protected:
 476   // Mirrors for primitive classes (created eagerly)
 477   static oop check_mirror(oop m) {
 478     assert(m != NULL, "mirror not initialized");
 479     return m;
 480   }
 481 
 482 public:
 483   // Note:  java_lang_Class::primitive_type is the inverse of java_mirror
 484 
 485   // Check class loader constraints
 486   static bool add_loader_constraint(Symbol* name, Handle loader1,
 487                                     Handle loader2, TRAPS);
 488   static Symbol* check_signature_loaders(Symbol* signature, Handle loader1,
 489                                          Handle loader2, bool is_method, TRAPS);
 490 
 491   // JSR 292
 492   // find a java.lang.invoke.MethodHandle.invoke* method for a given signature
 493   // (asks Java to compute it if necessary, except in a compiler thread)
 494   static methodHandle find_method_handle_invoker(Klass* klass,
 495                                                  Symbol* name,
 496                                                  Symbol* signature,
 497                                                  Klass* accessing_klass,
 498                                                  Handle *appendix_result,
 499                                                  Handle *method_type_result,
 500                                                  TRAPS);
 501   // for a given signature, find the internal MethodHandle method (linkTo* or invokeBasic)
 502   // (does not ask Java, since this is a low-level intrinsic defined by the JVM)
 503   static methodHandle find_method_handle_intrinsic(vmIntrinsics::ID iid,
 504                                                    Symbol* signature,
 505                                                    TRAPS);
 506 
 507   // compute java_mirror (java.lang.Class instance) for a type ("I", "[[B", "LFoo;", etc.)
 508   // Either the accessing_klass or the CL/PD can be non-null, but not both.
 509   static Handle    find_java_mirror_for_type(Symbol* signature,
 510                                              Klass* accessing_klass,
 511                                              Handle class_loader,
 512                                              Handle protection_domain,
 513                                              SignatureStream::FailureMode failure_mode,
 514                                              TRAPS);
 515   static Handle    find_java_mirror_for_type(Symbol* signature,
 516                                              Klass* accessing_klass,
 517                                              SignatureStream::FailureMode failure_mode,
 518                                              TRAPS) {
 519     // callee will fill in CL/PD from AK, if they are needed
 520     return find_java_mirror_for_type(signature, accessing_klass, Handle(), Handle(),
 521                                      failure_mode, THREAD);
 522   }
 523 
 524 
 525   // fast short-cut for the one-character case:
 526   static oop       find_java_mirror_for_type(char signature_char);
 527 
 528   // find a java.lang.invoke.MethodType object for a given signature
 529   // (asks Java to compute it if necessary, except in a compiler thread)
 530   static Handle    find_method_handle_type(Symbol* signature,
 531                                            Klass* accessing_klass,
 532                                            TRAPS);
 533 
 534   // find a java.lang.Class object for a given signature
 535   static Handle    find_field_handle_type(Symbol* signature,
 536                                           Klass* accessing_klass,
 537                                           TRAPS);
 538 
 539   // ask Java to compute a java.lang.invoke.MethodHandle object for a given CP entry
 540   static Handle    link_method_handle_constant(Klass* caller,
 541                                                int ref_kind, //e.g., JVM_REF_invokeVirtual
 542                                                Klass* callee,
 543                                                Symbol* name,
 544                                                Symbol* signature,
 545                                                TRAPS);
 546 
 547   // ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry
 548   static Handle    link_dynamic_constant(Klass* caller,
 549                                          int condy_index,
 550                                          Handle bootstrap_specifier,
 551                                          Symbol* name,
 552                                          Symbol* type,
 553                                          TRAPS);
 554 
 555   // ask Java to create a dynamic call site, while linking an invokedynamic op
 556   static methodHandle find_dynamic_call_site_invoker(Klass* caller,
 557                                                      int indy_index,
 558                                                      Handle bootstrap_method,
 559                                                      Symbol* name,
 560                                                      Symbol* type,
 561                                                      Handle *appendix_result,
 562                                                      Handle *method_type_result,
 563                                                      TRAPS);
 564 
 565   // Record the error when the first attempt to resolve a reference from a constant
 566   // pool entry to a class fails.
 567   static void add_resolution_error(const constantPoolHandle& pool, int which, Symbol* error,
 568                                    Symbol* message);
 569   static void delete_resolution_error(ConstantPool* pool);
 570   static Symbol* find_resolution_error(const constantPoolHandle& pool, int which,
 571                                        Symbol** message);
 572 
 573 
 574   static ProtectionDomainCacheEntry* cache_get(Handle protection_domain);
 575 
 576  protected:
 577 
 578   enum Constants {
 579     _loader_constraint_size = 107,                     // number of entries in constraint table
 580     _resolution_error_size  = 107,                     // number of entries in resolution error table
 581     _invoke_method_size     = 139,                     // number of entries in invoke method table
 582     _shared_dictionary_size = 1009,                    // number of entries in shared dictionary
 583     _placeholder_table_size = 1009                     // number of entries in hash table for placeholders
 584   };
 585 
 586 
 587   // Static tables owned by the SystemDictionary
 588 
 589   // Hashtable holding placeholders for classes being loaded.
 590   static PlaceholderTable*       _placeholders;
 591 
 592   // Hashtable holding classes from the shared archive.
 593   static Dictionary*             _shared_dictionary;
 594 
 595   // Monotonically increasing counter which grows with
 596   // loading classes as well as hot-swapping and breakpoint setting
 597   // and removal.
 598   static int                     _number_of_modifications;
 599 
 600   // Lock object for system class loader
 601   static oop                     _system_loader_lock_obj;
 602 
 603   // Constraints on class loaders
 604   static LoaderConstraintTable*  _loader_constraints;
 605 
 606   // Resolution errors
 607   static ResolutionErrorTable*   _resolution_errors;
 608 
 609   // Invoke methods (JSR 292)
 610   static SymbolPropertyTable*    _invoke_method_table;
 611 
 612   // ProtectionDomain cache
 613   static ProtectionDomainCacheTable*   _pd_cache_table;
 614 
 615   // VM weak OopStorage object.
 616   static OopStorage*             _vm_weak_oop_storage;
 617 
 618 protected:
 619   static void validate_protection_domain(InstanceKlass* klass,
 620                                          Handle class_loader,
 621                                          Handle protection_domain, TRAPS);
 622 
 623   friend class VM_PopulateDumpSharedSpace;
 624   friend class TraversePlaceholdersClosure;
 625   static Dictionary*         shared_dictionary() { return _shared_dictionary; }
 626   static PlaceholderTable*   placeholders() { return _placeholders; }
 627   static LoaderConstraintTable* constraints() { return _loader_constraints; }
 628   static ResolutionErrorTable* resolution_errors() { return _resolution_errors; }
 629   static SymbolPropertyTable* invoke_method_table() { return _invoke_method_table; }
 630 
 631   // Basic loading operations
 632   static InstanceKlass* resolve_instance_class_or_null_helper(Symbol* name,
 633                                                               Handle class_loader,
 634                                                               Handle protection_domain,
 635                                                               TRAPS);
 636   static InstanceKlass* resolve_instance_class_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);
 637   static Klass* resolve_array_class_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);
 638   static InstanceKlass* handle_parallel_super_load(Symbol* class_name, Symbol* supername, Handle class_loader, Handle protection_domain, Handle lockObject, TRAPS);
 639   // Wait on SystemDictionary_lock; unlocks lockObject before
 640   // waiting; relocks lockObject with correct recursion count
 641   // after waiting, but before reentering SystemDictionary_lock
 642   // to preserve lock order semantics.
 643   static void double_lock_wait(Handle lockObject, TRAPS);
 644   static void define_instance_class(InstanceKlass* k, TRAPS);
 645   static InstanceKlass* find_or_define_instance_class(Symbol* class_name,
 646                                                 Handle class_loader,
 647                                                 InstanceKlass* k, TRAPS);
 648   static bool is_shared_class_visible(Symbol* class_name, InstanceKlass* ik,
 649                                       Handle class_loader, TRAPS);
 650   static InstanceKlass* load_shared_class(InstanceKlass* ik,
 651                                           Handle class_loader,
 652                                           Handle protection_domain,
 653                                           TRAPS);
 654   static InstanceKlass* load_instance_class(Symbol* class_name, Handle class_loader, TRAPS);
 655   static Handle compute_loader_lock_object(Handle class_loader, TRAPS);
 656   static void check_loader_lock_contention(Handle loader_lock, TRAPS);
 657   static bool is_parallelCapable(Handle class_loader);
 658   static bool is_parallelDefine(Handle class_loader);
 659 
 660 public:
 661   static InstanceKlass* load_shared_class(Symbol* class_name,
 662                                           Handle class_loader,
 663                                           TRAPS);
 664   static bool is_system_class_loader(oop class_loader);
 665   static bool is_platform_class_loader(oop class_loader);
 666   static void clear_invoke_method_table();
 667 
 668   // Returns TRUE if the method is a non-public member of class java.lang.Object.
 669   static bool is_nonpublic_Object_method(Method* m) {
 670     assert(m != NULL, "Unexpected NULL Method*");
 671     return !m->is_public() && m->method_holder() == SystemDictionary::Object_klass();
 672   }
 673 
 674   static void initialize_oop_storage();
 675   static OopStorage* vm_weak_oop_storage();
 676 
 677 protected:
 678   static InstanceKlass* find_shared_class(Symbol* class_name);
 679 
 680   // Setup link to hierarchy
 681   static void add_to_hierarchy(InstanceKlass* k, TRAPS);
 682 
 683   // Basic find on loaded classes
 684   static InstanceKlass* find_class(unsigned int hash,
 685                                    Symbol* name, Dictionary* dictionary);
 686   static InstanceKlass* find_class(Symbol* class_name, ClassLoaderData* loader_data);
 687 
 688   // Basic find on classes in the midst of being loaded
 689   static Symbol* find_placeholder(Symbol* name, ClassLoaderData* loader_data);
 690 
 691   // Add a placeholder for a class being loaded
 692   static void add_placeholder(int index,
 693                               Symbol* class_name,
 694                               ClassLoaderData* loader_data);
 695   static void remove_placeholder(int index,
 696                                  Symbol* class_name,
 697                                  ClassLoaderData* loader_data);
 698 
 699   // Performs cleanups after resolve_super_or_fail. This typically needs
 700   // to be called on failure.
 701   // Won't throw, but can block.
 702   static void resolution_cleanups(Symbol* class_name,
 703                                   ClassLoaderData* loader_data,
 704                                   TRAPS);
 705 
 706   // Resolve well_known classes so they can be used like SystemDictionary::String_klass()
 707   static void resolve_well_known_classes(TRAPS);
 708 
 709   // Class loader constraints
 710   static void check_constraints(unsigned int hash,
 711                                 InstanceKlass* k, Handle loader,
 712                                 bool defining, TRAPS);
 713   static void update_dictionary(unsigned int d_hash,
 714                                 int p_index, unsigned int p_hash,
 715                                 InstanceKlass* k, Handle loader,
 716                                 TRAPS);
 717 

 718   static InstanceKlass* _well_known_klasses[];
 719 
 720   // table of box klasses (int_klass, etc.)
 721   static InstanceKlass* _box_klasses[T_VOID+1];
 722 
 723 private:
 724   static oop  _java_system_loader;
 725   static oop  _java_platform_loader;
 726 
 727   static bool _has_checkPackageAccess;
 728 };
 729 
 730 #endif // SHARE_VM_CLASSFILE_SYSTEMDICTIONARY_HPP
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