1 /*
   2  * Copyright (c) 1997, 2017, 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.
   8  *
   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).
  14  *
  15  * You should have received a copy of the GNU General Public License version
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  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
  21  * questions.
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  24 
  25 #ifndef SHARE_VM_OOPS_CONSTANTPOOLOOP_HPP
  26 #define SHARE_VM_OOPS_CONSTANTPOOLOOP_HPP
  27 
  28 #include "oops/arrayOop.hpp"
  29 #include "oops/cpCache.hpp"
  30 #include "oops/objArrayOop.hpp"
  31 #include "oops/symbol.hpp"
  32 #include "oops/typeArrayOop.hpp"
  33 #include "runtime/handles.hpp"
  34 #include "utilities/bytes.hpp"
  35 #include "utilities/constantTag.hpp"
  36 
  37 // A ConstantPool is an array containing class constants as described in the
  38 // class file.
  39 //
  40 // Most of the constant pool entries are written during class parsing, which
  41 // is safe.  For klass types, the constant pool entry is
  42 // modified when the entry is resolved.  If a klass constant pool
  43 // entry is read without a lock, only the resolved state guarantees that
  44 // the entry in the constant pool is a klass object and not a Symbol*.
  45 
  46 class SymbolHashMap;
  47 
  48 class CPSlot VALUE_OBJ_CLASS_SPEC {
  49  friend class ConstantPool;
  50   intptr_t _ptr;
  51   enum TagBits  {_pseudo_bit = 1};
  52  public:
  53 
  54   CPSlot(intptr_t ptr): _ptr(ptr) {}
  55   CPSlot(Symbol* ptr, int tag_bits = 0): _ptr((intptr_t)ptr | tag_bits) {}
  56 
  57   intptr_t value()   { return _ptr; }
  58   bool is_pseudo_string() { return (_ptr & _pseudo_bit) != 0; }
  59 
  60   Symbol* get_symbol() {
  61     return (Symbol*)(_ptr & ~_pseudo_bit);
  62   }
  63 };
  64 
  65 // This represents a JVM_CONSTANT_Class, JVM_CONSTANT_UnresolvedClass, or
  66 // JVM_CONSTANT_UnresolvedClassInError slot in the constant pool.
  67 class CPKlassSlot VALUE_OBJ_CLASS_SPEC {
  68   // cp->symbol_at(_name_index) gives the name of the class.
  69   int _name_index;
  70 
  71   // cp->_resolved_klasses->at(_resolved_klass_index) gives the Klass* for the class.
  72   int _resolved_klass_index;
  73 public:
  74   enum {
  75     // This is used during constant pool merging where the resolved klass index is
  76     // not yet known, and will be computed at a later stage (during a call to
  77     // initialize_unresolved_klasses()).
  78     _temp_resolved_klass_index = 0xffff
  79   };
  80   CPKlassSlot(int n, int rk) {
  81     _name_index = n;
  82     _resolved_klass_index = rk;
  83   }
  84   int name_index() const {
  85     return _name_index;
  86   }
  87   int resolved_klass_index() const {
  88     assert(_resolved_klass_index != _temp_resolved_klass_index, "constant pool merging was incomplete");
  89     return _resolved_klass_index;
  90   }
  91 };
  92 
  93 class KlassSizeStats;
  94 
  95 class ConstantPool : public Metadata {
  96   friend class VMStructs;
  97   friend class JVMCIVMStructs;
  98   friend class BytecodeInterpreter;  // Directly extracts a klass in the pool for fast instanceof/checkcast
  99   friend class Universe;             // For null constructor
 100  private:
 101   Array<u1>*           _tags;        // the tag array describing the constant pool's contents
 102   ConstantPoolCache*   _cache;       // the cache holding interpreter runtime information
 103   InstanceKlass*       _pool_holder; // the corresponding class
 104   Array<u2>*           _operands;    // for variable-sized (InvokeDynamic) nodes, usually empty
 105 
 106   // Consider using an array of compressed klass pointers to
 107   // save space on 64-bit platforms.
 108   Array<Klass*>*       _resolved_klasses;
 109 
 110   enum {
 111     _has_preresolution = 1,           // Flags
 112     _on_stack          = 2,
 113     _is_shared         = 4
 114   };
 115 
 116   int                  _flags;  // old fashioned bit twiddling
 117   int                  _length; // number of elements in the array
 118 
 119   union {
 120     // set for CDS to restore resolved references
 121     int                _resolved_reference_length;
 122     // keeps version number for redefined classes (used in backtrace)
 123     int                _version;
 124   } _saved;
 125 
 126   void set_tags(Array<u1>* tags)               { _tags = tags; }
 127   void tag_at_put(int which, jbyte t)          { tags()->at_put(which, t); }
 128   void release_tag_at_put(int which, jbyte t)  { tags()->release_at_put(which, t); }
 129 
 130   u1* tag_addr_at(int which) const             { return tags()->adr_at(which); }
 131 
 132   void set_operands(Array<u2>* operands)       { _operands = operands; }
 133 
 134   int flags() const                            { return _flags; }
 135   void set_flags(int f)                        { _flags = f; }
 136 
 137  private:
 138   intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(ConstantPool)); }
 139 
 140   CPSlot slot_at(int which) const {
 141     assert(is_within_bounds(which), "index out of bounds");
 142     assert(!tag_at(which).is_unresolved_klass() && !tag_at(which).is_unresolved_klass_in_error(), "Corrupted constant pool");
 143     // Uses volatile because the klass slot changes without a lock.
 144     volatile intptr_t adr = (intptr_t)OrderAccess::load_ptr_acquire(obj_at_addr_raw(which));
 145     assert(adr != 0 || which == 0, "cp entry for klass should not be zero");
 146     return CPSlot(adr);
 147   }
 148 
 149   void slot_at_put(int which, CPSlot s) const {
 150     assert(is_within_bounds(which), "index out of bounds");
 151     assert(s.value() != 0, "Caught something");
 152     *(intptr_t*)&base()[which] = s.value();
 153   }
 154   intptr_t* obj_at_addr_raw(int which) const {
 155     assert(is_within_bounds(which), "index out of bounds");
 156     return (intptr_t*) &base()[which];
 157   }
 158 
 159   jint* int_at_addr(int which) const {
 160     assert(is_within_bounds(which), "index out of bounds");
 161     return (jint*) &base()[which];
 162   }
 163 
 164   jlong* long_at_addr(int which) const {
 165     assert(is_within_bounds(which), "index out of bounds");
 166     return (jlong*) &base()[which];
 167   }
 168 
 169   jfloat* float_at_addr(int which) const {
 170     assert(is_within_bounds(which), "index out of bounds");
 171     return (jfloat*) &base()[which];
 172   }
 173 
 174   jdouble* double_at_addr(int which) const {
 175     assert(is_within_bounds(which), "index out of bounds");
 176     return (jdouble*) &base()[which];
 177   }
 178 
 179   ConstantPool(Array<u1>* tags);
 180   ConstantPool() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }
 181  public:
 182   static ConstantPool* allocate(ClassLoaderData* loader_data, int length, TRAPS);
 183 
 184   bool is_constantPool() const volatile     { return true; }
 185 
 186   Array<u1>* tags() const                   { return _tags; }
 187   Array<u2>* operands() const               { return _operands; }
 188 
 189   bool has_preresolution() const            { return (_flags & _has_preresolution) != 0; }
 190   void set_has_preresolution() {
 191     assert(!is_shared(), "should never be called on shared ConstantPools");
 192     _flags |= _has_preresolution;
 193   }
 194 
 195   // Redefine classes support.  If a method refering to this constant pool
 196   // is on the executing stack, or as a handle in vm code, this constant pool
 197   // can't be removed from the set of previous versions saved in the instance
 198   // class.
 199   bool on_stack() const                      { return (_flags &_on_stack) != 0; }
 200   void set_on_stack(const bool value);
 201 
 202   // Faster than MetaspaceObj::is_shared() - used by set_on_stack()
 203   bool is_shared() const                     { return (_flags & _is_shared) != 0; }
 204 
 205   // Klass holding pool
 206   InstanceKlass* pool_holder() const      { return _pool_holder; }
 207   void set_pool_holder(InstanceKlass* k)  { _pool_holder = k; }
 208   InstanceKlass** pool_holder_addr()      { return &_pool_holder; }
 209 
 210   // Interpreter runtime support
 211   ConstantPoolCache* cache() const        { return _cache; }
 212   void set_cache(ConstantPoolCache* cache){ _cache = cache; }
 213 
 214   // Create object cache in the constant pool
 215   void initialize_resolved_references(ClassLoaderData* loader_data,
 216                                       const intStack& reference_map,
 217                                       int constant_pool_map_length,
 218                                       TRAPS);
 219 
 220   // resolved strings, methodHandles and callsite objects from the constant pool
 221   objArrayOop resolved_references()  const;
 222   // mapping resolved object array indexes to cp indexes and back.
 223   int object_to_cp_index(int index)         { return reference_map()->at(index); }
 224   int cp_to_object_index(int index);
 225 
 226   void set_resolved_klasses(Array<Klass*>* rk)  { _resolved_klasses = rk; }
 227   Array<Klass*>* resolved_klasses() const       { return _resolved_klasses; }
 228   void allocate_resolved_klasses(ClassLoaderData* loader_data, int num_klasses, TRAPS);
 229   void initialize_unresolved_klasses(ClassLoaderData* loader_data, TRAPS);
 230 
 231   // Invokedynamic indexes.
 232   // They must look completely different from normal indexes.
 233   // The main reason is that byte swapping is sometimes done on normal indexes.
 234   // Finally, it is helpful for debugging to tell the two apart.
 235   static bool is_invokedynamic_index(int i) { return (i < 0); }
 236   static int  decode_invokedynamic_index(int i) { assert(is_invokedynamic_index(i),  ""); return ~i; }
 237   static int  encode_invokedynamic_index(int i) { assert(!is_invokedynamic_index(i), ""); return ~i; }
 238 
 239 
 240   // The invokedynamic points at a CP cache entry.  This entry points back
 241   // at the original CP entry (CONSTANT_InvokeDynamic) and also (via f2) at an entry
 242   // in the resolved_references array (which provides the appendix argument).
 243   int invokedynamic_cp_cache_index(int index) const {
 244     assert (is_invokedynamic_index(index), "should be a invokedynamic index");
 245     int cache_index = decode_invokedynamic_index(index);
 246     return cache_index;
 247   }
 248   ConstantPoolCacheEntry* invokedynamic_cp_cache_entry_at(int index) const {
 249     // decode index that invokedynamic points to.
 250     int cp_cache_index = invokedynamic_cp_cache_index(index);
 251     return cache()->entry_at(cp_cache_index);
 252   }
 253 
 254   // Assembly code support
 255   static int tags_offset_in_bytes()         { return offset_of(ConstantPool, _tags); }
 256   static int cache_offset_in_bytes()        { return offset_of(ConstantPool, _cache); }
 257   static int pool_holder_offset_in_bytes()  { return offset_of(ConstantPool, _pool_holder); }
 258   static int resolved_klasses_offset_in_bytes()    { return offset_of(ConstantPool, _resolved_klasses); }
 259 
 260   // Storing constants
 261 
 262   // For temporary use while constructing constant pool
 263   void klass_index_at_put(int which, int name_index) {
 264     tag_at_put(which, JVM_CONSTANT_ClassIndex);
 265     *int_at_addr(which) = name_index;
 266   }
 267 
 268   // Anonymous class support:
 269   void klass_at_put(int class_index, int name_index, int resolved_klass_index, Klass* k, Symbol* name);
 270   void klass_at_put(int class_index, Klass* k);
 271 
 272   void unresolved_klass_at_put(int which, int name_index, int resolved_klass_index) {
 273     release_tag_at_put(which, JVM_CONSTANT_UnresolvedClass);
 274 
 275     assert((name_index & 0xffff0000) == 0, "must be");
 276     assert((resolved_klass_index & 0xffff0000) == 0, "must be");
 277     *int_at_addr(which) =
 278       build_int_from_shorts((jushort)resolved_klass_index, (jushort)name_index);
 279   }
 280 
 281   void method_handle_index_at_put(int which, int ref_kind, int ref_index) {
 282     tag_at_put(which, JVM_CONSTANT_MethodHandle);
 283     *int_at_addr(which) = ((jint) ref_index<<16) | ref_kind;
 284   }
 285 
 286   void method_type_index_at_put(int which, int ref_index) {
 287     tag_at_put(which, JVM_CONSTANT_MethodType);
 288     *int_at_addr(which) = ref_index;
 289   }
 290 
 291   void invoke_dynamic_at_put(int which, int bootstrap_specifier_index, int name_and_type_index) {
 292     tag_at_put(which, JVM_CONSTANT_InvokeDynamic);
 293     *int_at_addr(which) = ((jint) name_and_type_index<<16) | bootstrap_specifier_index;
 294   }
 295 
 296   void unresolved_string_at_put(int which, Symbol* s) {
 297     release_tag_at_put(which, JVM_CONSTANT_String);
 298     slot_at_put(which, CPSlot(s));
 299   }
 300 
 301   void int_at_put(int which, jint i) {
 302     tag_at_put(which, JVM_CONSTANT_Integer);
 303     *int_at_addr(which) = i;
 304   }
 305 
 306   void long_at_put(int which, jlong l) {
 307     tag_at_put(which, JVM_CONSTANT_Long);
 308     // *long_at_addr(which) = l;
 309     Bytes::put_native_u8((address)long_at_addr(which), *((u8*) &l));
 310   }
 311 
 312   void float_at_put(int which, jfloat f) {
 313     tag_at_put(which, JVM_CONSTANT_Float);
 314     *float_at_addr(which) = f;
 315   }
 316 
 317   void double_at_put(int which, jdouble d) {
 318     tag_at_put(which, JVM_CONSTANT_Double);
 319     // *double_at_addr(which) = d;
 320     // u8 temp = *(u8*) &d;
 321     Bytes::put_native_u8((address) double_at_addr(which), *((u8*) &d));
 322   }
 323 
 324   Symbol** symbol_at_addr(int which) const {
 325     assert(is_within_bounds(which), "index out of bounds");
 326     return (Symbol**) &base()[which];
 327   }
 328 
 329   void symbol_at_put(int which, Symbol* s) {
 330     assert(s->refcount() != 0, "should have nonzero refcount");
 331     tag_at_put(which, JVM_CONSTANT_Utf8);
 332     *symbol_at_addr(which) = s;
 333   }
 334 
 335   void string_at_put(int which, int obj_index, oop str);
 336 
 337   // For temporary use while constructing constant pool
 338   void string_index_at_put(int which, int string_index) {
 339     tag_at_put(which, JVM_CONSTANT_StringIndex);
 340     *int_at_addr(which) = string_index;
 341   }
 342 
 343   void field_at_put(int which, int class_index, int name_and_type_index) {
 344     tag_at_put(which, JVM_CONSTANT_Fieldref);
 345     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
 346   }
 347 
 348   void method_at_put(int which, int class_index, int name_and_type_index) {
 349     tag_at_put(which, JVM_CONSTANT_Methodref);
 350     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
 351   }
 352 
 353   void interface_method_at_put(int which, int class_index, int name_and_type_index) {
 354     tag_at_put(which, JVM_CONSTANT_InterfaceMethodref);
 355     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;  // Not so nice
 356   }
 357 
 358   void name_and_type_at_put(int which, int name_index, int signature_index) {
 359     tag_at_put(which, JVM_CONSTANT_NameAndType);
 360     *int_at_addr(which) = ((jint) signature_index<<16) | name_index;  // Not so nice
 361   }
 362 
 363   // Tag query
 364 
 365   constantTag tag_at(int which) const { return (constantTag)tags()->at_acquire(which); }
 366 
 367   // Fetching constants
 368 
 369   Klass* klass_at(int which, TRAPS) {
 370     constantPoolHandle h_this(THREAD, this);
 371     return klass_at_impl(h_this, which, true, THREAD);
 372   }
 373 
 374   // Version of klass_at that doesn't save the resolution error, called during deopt
 375   Klass* klass_at_ignore_error(int which, TRAPS) {
 376     constantPoolHandle h_this(THREAD, this);
 377     return klass_at_impl(h_this, which, false, THREAD);
 378   }
 379 
 380   CPKlassSlot klass_slot_at(int which) const {
 381     assert(tag_at(which).is_unresolved_klass() || tag_at(which).is_klass(),
 382            "Corrupted constant pool");
 383     int value = *int_at_addr(which);
 384     int name_index = extract_high_short_from_int(value);
 385     int resolved_klass_index = extract_low_short_from_int(value);
 386     return CPKlassSlot(name_index, resolved_klass_index);
 387   }
 388 
 389   Symbol* klass_name_at(int which) const;  // Returns the name, w/o resolving.
 390   int klass_name_index_at(int which) const {
 391     return klass_slot_at(which).name_index();
 392   }
 393 
 394   Klass* resolved_klass_at(int which) const {  // Used by Compiler
 395     guarantee(tag_at(which).is_klass(), "Corrupted constant pool");
 396     // Must do an acquire here in case another thread resolved the klass
 397     // behind our back, lest we later load stale values thru the oop.
 398     CPKlassSlot kslot = klass_slot_at(which);
 399     assert(tag_at(kslot.name_index()).is_symbol(), "sanity");
 400 
 401     Klass** adr = resolved_klasses()->adr_at(kslot.resolved_klass_index());
 402     return (Klass*)OrderAccess::load_ptr_acquire(adr);
 403   }
 404 
 405   // RedefineClasses() API support:
 406   Symbol* klass_at_noresolve(int which) { return klass_name_at(which); }
 407   void temp_unresolved_klass_at_put(int which, int name_index) {
 408     // Used only during constant pool merging for class redefinition. The resolved klass index
 409     // will be initialized later by a call to initialize_unresolved_klasses().
 410     unresolved_klass_at_put(which, name_index, CPKlassSlot::_temp_resolved_klass_index);
 411   }
 412 
 413   jint int_at(int which) {
 414     assert(tag_at(which).is_int(), "Corrupted constant pool");
 415     return *int_at_addr(which);
 416   }
 417 
 418   jlong long_at(int which) {
 419     assert(tag_at(which).is_long(), "Corrupted constant pool");
 420     // return *long_at_addr(which);
 421     u8 tmp = Bytes::get_native_u8((address)&base()[which]);
 422     return *((jlong*)&tmp);
 423   }
 424 
 425   jfloat float_at(int which) {
 426     assert(tag_at(which).is_float(), "Corrupted constant pool");
 427     return *float_at_addr(which);
 428   }
 429 
 430   jdouble double_at(int which) {
 431     assert(tag_at(which).is_double(), "Corrupted constant pool");
 432     u8 tmp = Bytes::get_native_u8((address)&base()[which]);
 433     return *((jdouble*)&tmp);
 434   }
 435 
 436   Symbol* symbol_at(int which) const {
 437     assert(tag_at(which).is_utf8(), "Corrupted constant pool");
 438     return *symbol_at_addr(which);
 439   }
 440 
 441   oop string_at(int which, int obj_index, TRAPS) {
 442     constantPoolHandle h_this(THREAD, this);
 443     return string_at_impl(h_this, which, obj_index, THREAD);
 444   }
 445   oop string_at(int which, TRAPS) {
 446     int obj_index = cp_to_object_index(which);
 447     return string_at(which, obj_index, THREAD);
 448   }
 449 
 450   // Version that can be used before string oop array is created.
 451   oop uncached_string_at(int which, TRAPS);
 452 
 453   // A "pseudo-string" is an non-string oop that has found its way into
 454   // a String entry.
 455   // This can happen if the user patches a live
 456   // object into a CONSTANT_String entry of an anonymous class.
 457   // Method oops internally created for method handles may also
 458   // use pseudo-strings to link themselves to related metaobjects.
 459 
 460   bool is_pseudo_string_at(int which) {
 461     assert(tag_at(which).is_string(), "Corrupted constant pool");
 462     return slot_at(which).is_pseudo_string();
 463   }
 464 
 465   oop pseudo_string_at(int which, int obj_index) {
 466     assert(is_pseudo_string_at(which), "must be a pseudo-string");
 467     oop s = resolved_references()->obj_at(obj_index);
 468     return s;
 469   }
 470 
 471   oop pseudo_string_at(int which) {
 472     assert(is_pseudo_string_at(which), "must be a pseudo-string");
 473     int obj_index = cp_to_object_index(which);
 474     oop s = resolved_references()->obj_at(obj_index);
 475     return s;
 476   }
 477 
 478   void pseudo_string_at_put(int which, int obj_index, oop x) {
 479     assert(tag_at(which).is_string(), "Corrupted constant pool");
 480     Symbol* sym = unresolved_string_at(which);
 481     slot_at_put(which, CPSlot(sym, CPSlot::_pseudo_bit));
 482     string_at_put(which, obj_index, x);    // this works just fine
 483   }
 484 
 485   // only called when we are sure a string entry is already resolved (via an
 486   // earlier string_at call.
 487   oop resolved_string_at(int which) {
 488     assert(tag_at(which).is_string(), "Corrupted constant pool");
 489     // Must do an acquire here in case another thread resolved the klass
 490     // behind our back, lest we later load stale values thru the oop.
 491     // we might want a volatile_obj_at in ObjArrayKlass.
 492     int obj_index = cp_to_object_index(which);
 493     return resolved_references()->obj_at(obj_index);
 494   }
 495 
 496   Symbol* unresolved_string_at(int which) {
 497     assert(tag_at(which).is_string(), "Corrupted constant pool");
 498     Symbol* sym = slot_at(which).get_symbol();
 499     return sym;
 500   }
 501 
 502   // Returns an UTF8 for a CONSTANT_String entry at a given index.
 503   // UTF8 char* representation was chosen to avoid conversion of
 504   // java_lang_Strings at resolved entries into Symbol*s
 505   // or vice versa.
 506   char* string_at_noresolve(int which);
 507 
 508   jint name_and_type_at(int which) {
 509     assert(tag_at(which).is_name_and_type(), "Corrupted constant pool");
 510     return *int_at_addr(which);
 511   }
 512 
 513   int method_handle_ref_kind_at(int which) {
 514     assert(tag_at(which).is_method_handle() ||
 515            tag_at(which).is_method_handle_in_error(), "Corrupted constant pool");
 516     return extract_low_short_from_int(*int_at_addr(which));  // mask out unwanted ref_index bits
 517   }
 518   int method_handle_index_at(int which) {
 519     assert(tag_at(which).is_method_handle() ||
 520            tag_at(which).is_method_handle_in_error(), "Corrupted constant pool");
 521     return extract_high_short_from_int(*int_at_addr(which));  // shift out unwanted ref_kind bits
 522   }
 523   int method_type_index_at(int which) {
 524     assert(tag_at(which).is_method_type() ||
 525            tag_at(which).is_method_type_in_error(), "Corrupted constant pool");
 526     return *int_at_addr(which);
 527   }
 528 
 529   // Derived queries:
 530   Symbol* method_handle_name_ref_at(int which) {
 531     int member = method_handle_index_at(which);
 532     return impl_name_ref_at(member, true);
 533   }
 534   Symbol* method_handle_signature_ref_at(int which) {
 535     int member = method_handle_index_at(which);
 536     return impl_signature_ref_at(member, true);
 537   }
 538   int method_handle_klass_index_at(int which) {
 539     int member = method_handle_index_at(which);
 540     return impl_klass_ref_index_at(member, true);
 541   }
 542   Symbol* method_type_signature_at(int which) {
 543     int sym = method_type_index_at(which);
 544     return symbol_at(sym);
 545   }
 546 
 547   int invoke_dynamic_name_and_type_ref_index_at(int which) {
 548     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 549     return extract_high_short_from_int(*int_at_addr(which));
 550   }
 551   int invoke_dynamic_bootstrap_specifier_index(int which) {
 552     assert(tag_at(which).value() == JVM_CONSTANT_InvokeDynamic, "Corrupted constant pool");
 553     return extract_low_short_from_int(*int_at_addr(which));
 554   }
 555   int invoke_dynamic_operand_base(int which) {
 556     int bootstrap_specifier_index = invoke_dynamic_bootstrap_specifier_index(which);
 557     return operand_offset_at(operands(), bootstrap_specifier_index);
 558   }
 559   // The first part of the operands array consists of an index into the second part.
 560   // Extract a 32-bit index value from the first part.
 561   static int operand_offset_at(Array<u2>* operands, int bootstrap_specifier_index) {
 562     int n = (bootstrap_specifier_index * 2);
 563     assert(n >= 0 && n+2 <= operands->length(), "oob");
 564     // The first 32-bit index points to the beginning of the second part
 565     // of the operands array.  Make sure this index is in the first part.
 566     DEBUG_ONLY(int second_part = build_int_from_shorts(operands->at(0),
 567                                                        operands->at(1)));
 568     assert(second_part == 0 || n+2 <= second_part, "oob (2)");
 569     int offset = build_int_from_shorts(operands->at(n+0),
 570                                        operands->at(n+1));
 571     // The offset itself must point into the second part of the array.
 572     assert(offset == 0 || offset >= second_part && offset <= operands->length(), "oob (3)");
 573     return offset;
 574   }
 575   static void operand_offset_at_put(Array<u2>* operands, int bootstrap_specifier_index, int offset) {
 576     int n = bootstrap_specifier_index * 2;
 577     assert(n >= 0 && n+2 <= operands->length(), "oob");
 578     operands->at_put(n+0, extract_low_short_from_int(offset));
 579     operands->at_put(n+1, extract_high_short_from_int(offset));
 580   }
 581   static int operand_array_length(Array<u2>* operands) {
 582     if (operands == NULL || operands->length() == 0)  return 0;
 583     int second_part = operand_offset_at(operands, 0);
 584     return (second_part / 2);
 585   }
 586 
 587 #ifdef ASSERT
 588   // operand tuples fit together exactly, end to end
 589   static int operand_limit_at(Array<u2>* operands, int bootstrap_specifier_index) {
 590     int nextidx = bootstrap_specifier_index + 1;
 591     if (nextidx == operand_array_length(operands))
 592       return operands->length();
 593     else
 594       return operand_offset_at(operands, nextidx);
 595   }
 596   int invoke_dynamic_operand_limit(int which) {
 597     int bootstrap_specifier_index = invoke_dynamic_bootstrap_specifier_index(which);
 598     return operand_limit_at(operands(), bootstrap_specifier_index);
 599   }
 600 #endif //ASSERT
 601 
 602   // layout of InvokeDynamic bootstrap method specifier (in second part of operands array):
 603   enum {
 604          _indy_bsm_offset  = 0,  // CONSTANT_MethodHandle bsm
 605          _indy_argc_offset = 1,  // u2 argc
 606          _indy_argv_offset = 2   // u2 argv[argc]
 607   };
 608 
 609   // These functions are used in RedefineClasses for CP merge
 610 
 611   int operand_offset_at(int bootstrap_specifier_index) {
 612     assert(0 <= bootstrap_specifier_index &&
 613            bootstrap_specifier_index < operand_array_length(operands()),
 614            "Corrupted CP operands");
 615     return operand_offset_at(operands(), bootstrap_specifier_index);
 616   }
 617   int operand_bootstrap_method_ref_index_at(int bootstrap_specifier_index) {
 618     int offset = operand_offset_at(bootstrap_specifier_index);
 619     return operands()->at(offset + _indy_bsm_offset);
 620   }
 621   int operand_argument_count_at(int bootstrap_specifier_index) {
 622     int offset = operand_offset_at(bootstrap_specifier_index);
 623     int argc = operands()->at(offset + _indy_argc_offset);
 624     return argc;
 625   }
 626   int operand_argument_index_at(int bootstrap_specifier_index, int j) {
 627     int offset = operand_offset_at(bootstrap_specifier_index);
 628     return operands()->at(offset + _indy_argv_offset + j);
 629   }
 630   int operand_next_offset_at(int bootstrap_specifier_index) {
 631     int offset = operand_offset_at(bootstrap_specifier_index) + _indy_argv_offset
 632                    + operand_argument_count_at(bootstrap_specifier_index);
 633     return offset;
 634   }
 635   // Compare a bootsrap specifier in the operands arrays
 636   bool compare_operand_to(int bootstrap_specifier_index1, const constantPoolHandle& cp2,
 637                           int bootstrap_specifier_index2, TRAPS);
 638   // Find a bootsrap specifier in the operands array
 639   int find_matching_operand(int bootstrap_specifier_index, const constantPoolHandle& search_cp,
 640                             int operands_cur_len, TRAPS);
 641   // Resize the operands array with delta_len and delta_size
 642   void resize_operands(int delta_len, int delta_size, TRAPS);
 643   // Extend the operands array with the length and size of the ext_cp operands
 644   void extend_operands(const constantPoolHandle& ext_cp, TRAPS);
 645   // Shrink the operands array to a smaller array with new_len length
 646   void shrink_operands(int new_len, TRAPS);
 647 
 648 
 649   int invoke_dynamic_bootstrap_method_ref_index_at(int which) {
 650     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 651     int op_base = invoke_dynamic_operand_base(which);
 652     return operands()->at(op_base + _indy_bsm_offset);
 653   }
 654   int invoke_dynamic_argument_count_at(int which) {
 655     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 656     int op_base = invoke_dynamic_operand_base(which);
 657     int argc = operands()->at(op_base + _indy_argc_offset);
 658     DEBUG_ONLY(int end_offset = op_base + _indy_argv_offset + argc;
 659                int next_offset = invoke_dynamic_operand_limit(which));
 660     assert(end_offset == next_offset, "matched ending");
 661     return argc;
 662   }
 663   int invoke_dynamic_argument_index_at(int which, int j) {
 664     int op_base = invoke_dynamic_operand_base(which);
 665     DEBUG_ONLY(int argc = operands()->at(op_base + _indy_argc_offset));
 666     assert((uint)j < (uint)argc, "oob");
 667     return operands()->at(op_base + _indy_argv_offset + j);
 668   }
 669 
 670   // The following methods (name/signature/klass_ref_at, klass_ref_at_noresolve,
 671   // name_and_type_ref_index_at) all expect to be passed indices obtained
 672   // directly from the bytecode.
 673   // If the indices are meant to refer to fields or methods, they are
 674   // actually rewritten constant pool cache indices.
 675   // The routine remap_instruction_operand_from_cache manages the adjustment
 676   // of these values back to constant pool indices.
 677 
 678   // There are also "uncached" versions which do not adjust the operand index; see below.
 679 
 680   // FIXME: Consider renaming these with a prefix "cached_" to make the distinction clear.
 681   // In a few cases (the verifier) there are uses before a cpcache has been built,
 682   // which are handled by a dynamic check in remap_instruction_operand_from_cache.
 683   // FIXME: Remove the dynamic check, and adjust all callers to specify the correct mode.
 684 
 685   // Lookup for entries consisting of (klass_index, name_and_type index)
 686   Klass* klass_ref_at(int which, TRAPS);
 687   Symbol* klass_ref_at_noresolve(int which);
 688   Symbol* name_ref_at(int which)                { return impl_name_ref_at(which, false); }
 689   Symbol* signature_ref_at(int which)           { return impl_signature_ref_at(which, false); }
 690 
 691   int klass_ref_index_at(int which)               { return impl_klass_ref_index_at(which, false); }
 692   int name_and_type_ref_index_at(int which)       { return impl_name_and_type_ref_index_at(which, false); }
 693 
 694   int remap_instruction_operand_from_cache(int operand);  // operand must be biased by CPCACHE_INDEX_TAG
 695 
 696   constantTag tag_ref_at(int cp_cache_index)      { return impl_tag_ref_at(cp_cache_index, false); }
 697 
 698   // Lookup for entries consisting of (name_index, signature_index)
 699   int name_ref_index_at(int which_nt);            // ==  low-order jshort of name_and_type_at(which_nt)
 700   int signature_ref_index_at(int which_nt);       // == high-order jshort of name_and_type_at(which_nt)
 701 
 702   BasicType basic_type_for_signature_at(int which) const;
 703 
 704   // Resolve string constants (to prevent allocation during compilation)
 705   void resolve_string_constants(TRAPS) {
 706     constantPoolHandle h_this(THREAD, this);
 707     resolve_string_constants_impl(h_this, CHECK);
 708   }
 709 
 710   // CDS support
 711   void remove_unshareable_info();
 712   void restore_unshareable_info(TRAPS);
 713   bool resolve_class_constants(TRAPS);
 714   // The ConstantPool vtable is restored by this call when the ConstantPool is
 715   // in the shared archive.  See patch_klass_vtables() in metaspaceShared.cpp for
 716   // all the gory details.  SA, dtrace and pstack helpers distinguish metadata
 717   // by their vtable.
 718   void restore_vtable() { guarantee(is_constantPool(), "vtable restored by this call"); }
 719 
 720  private:
 721   enum { _no_index_sentinel = -1, _possible_index_sentinel = -2 };
 722  public:
 723 
 724   // Resolve late bound constants.
 725   oop resolve_constant_at(int index, TRAPS) {
 726     constantPoolHandle h_this(THREAD, this);
 727     return resolve_constant_at_impl(h_this, index, _no_index_sentinel, THREAD);
 728   }
 729 
 730   oop resolve_cached_constant_at(int cache_index, TRAPS) {
 731     constantPoolHandle h_this(THREAD, this);
 732     return resolve_constant_at_impl(h_this, _no_index_sentinel, cache_index, THREAD);
 733   }
 734 
 735   oop resolve_possibly_cached_constant_at(int pool_index, TRAPS) {
 736     constantPoolHandle h_this(THREAD, this);
 737     return resolve_constant_at_impl(h_this, pool_index, _possible_index_sentinel, THREAD);
 738   }
 739 
 740   oop resolve_bootstrap_specifier_at(int index, TRAPS) {
 741     constantPoolHandle h_this(THREAD, this);
 742     return resolve_bootstrap_specifier_at_impl(h_this, index, THREAD);
 743   }
 744 
 745   // Klass name matches name at offset
 746   bool klass_name_at_matches(const InstanceKlass* k, int which);
 747 
 748   // Sizing
 749   int length() const                   { return _length; }
 750   void set_length(int length)          { _length = length; }
 751 
 752   // Tells whether index is within bounds.
 753   bool is_within_bounds(int index) const {
 754     return 0 <= index && index < length();
 755   }
 756 
 757   // Sizing (in words)
 758   static int header_size()             {
 759     return align_size_up((int)sizeof(ConstantPool), wordSize) / wordSize;
 760   }
 761   static int size(int length)          { return align_metadata_size(header_size() + length); }
 762   int size() const                     { return size(length()); }
 763 #if INCLUDE_SERVICES
 764   void collect_statistics(KlassSizeStats *sz) const;
 765 #endif
 766 
 767   friend class ClassFileParser;
 768   friend class SystemDictionary;
 769 
 770   // Used by CDS. These classes need to access the private ConstantPool() constructor.
 771   template <class T> friend class CppVtableTesterA;
 772   template <class T> friend class CppVtableTesterB;
 773   template <class T> friend class CppVtableCloner;
 774 
 775   // Used by compiler to prevent classloading.
 776   static Method*          method_at_if_loaded      (const constantPoolHandle& this_cp, int which);
 777   static bool       has_appendix_at_if_loaded      (const constantPoolHandle& this_cp, int which);
 778   static oop            appendix_at_if_loaded      (const constantPoolHandle& this_cp, int which);
 779   static bool    has_method_type_at_if_loaded      (const constantPoolHandle& this_cp, int which);
 780   static oop         method_type_at_if_loaded      (const constantPoolHandle& this_cp, int which);
 781   static Klass*            klass_at_if_loaded      (const constantPoolHandle& this_cp, int which);
 782   static Klass*        klass_ref_at_if_loaded      (const constantPoolHandle& this_cp, int which);
 783 
 784   // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the
 785   // future by other Java code. These take constant pool indices rather than
 786   // constant pool cache indices as do the peer methods above.
 787   Symbol* uncached_klass_ref_at_noresolve(int which);
 788   Symbol* uncached_name_ref_at(int which)                 { return impl_name_ref_at(which, true); }
 789   Symbol* uncached_signature_ref_at(int which)            { return impl_signature_ref_at(which, true); }
 790   int       uncached_klass_ref_index_at(int which)          { return impl_klass_ref_index_at(which, true); }
 791   int       uncached_name_and_type_ref_index_at(int which)  { return impl_name_and_type_ref_index_at(which, true); }
 792 
 793   // Sharing
 794   int pre_resolve_shared_klasses(TRAPS);
 795 
 796   // Debugging
 797   const char* printable_name_at(int which) PRODUCT_RETURN0;
 798 
 799 #ifdef ASSERT
 800   enum { CPCACHE_INDEX_TAG = 0x10000 };  // helps keep CP cache indices distinct from CP indices
 801 #else
 802   enum { CPCACHE_INDEX_TAG = 0 };        // in product mode, this zero value is a no-op
 803 #endif //ASSERT
 804 
 805   static int decode_cpcache_index(int raw_index, bool invokedynamic_ok = false) {
 806     if (invokedynamic_ok && is_invokedynamic_index(raw_index))
 807       return decode_invokedynamic_index(raw_index);
 808     else
 809       return raw_index - CPCACHE_INDEX_TAG;
 810   }
 811 
 812  private:
 813 
 814   void set_resolved_references(jobject s) { _cache->set_resolved_references(s); }
 815   Array<u2>* reference_map() const        {  return (_cache == NULL) ? NULL :  _cache->reference_map(); }
 816   void set_reference_map(Array<u2>* o)    { _cache->set_reference_map(o); }
 817 
 818   // patch JSR 292 resolved references after the class is linked.
 819   void patch_resolved_references(GrowableArray<Handle>* cp_patches);
 820 
 821   Symbol* impl_name_ref_at(int which, bool uncached);
 822   Symbol* impl_signature_ref_at(int which, bool uncached);
 823   int       impl_klass_ref_index_at(int which, bool uncached);
 824   int       impl_name_and_type_ref_index_at(int which, bool uncached);
 825   constantTag impl_tag_ref_at(int which, bool uncached);
 826 
 827   // Used while constructing constant pool (only by ClassFileParser)
 828   jint klass_index_at(int which) {
 829     assert(tag_at(which).is_klass_index(), "Corrupted constant pool");
 830     return *int_at_addr(which);
 831   }
 832 
 833   jint string_index_at(int which) {
 834     assert(tag_at(which).is_string_index(), "Corrupted constant pool");
 835     return *int_at_addr(which);
 836   }
 837 
 838   // Performs the LinkResolver checks
 839   static void verify_constant_pool_resolve(const constantPoolHandle& this_cp, Klass* klass, TRAPS);
 840 
 841   // Implementation of methods that needs an exposed 'this' pointer, in order to
 842   // handle GC while executing the method
 843   static Klass* klass_at_impl(const constantPoolHandle& this_cp, int which,
 844                               bool save_resolution_error, TRAPS);
 845   static oop string_at_impl(const constantPoolHandle& this_cp, int which, int obj_index, TRAPS);
 846 
 847   static void trace_class_resolution(const constantPoolHandle& this_cp, Klass* k);
 848 
 849   // Resolve string constants (to prevent allocation during compilation)
 850   static void resolve_string_constants_impl(const constantPoolHandle& this_cp, TRAPS);
 851 
 852   static oop resolve_constant_at_impl(const constantPoolHandle& this_cp, int index, int cache_index, TRAPS);
 853   static oop resolve_bootstrap_specifier_at_impl(const constantPoolHandle& this_cp, int index, TRAPS);
 854 
 855   // Exception handling
 856   static void throw_resolution_error(const constantPoolHandle& this_cp, int which, TRAPS);
 857   static Symbol* exception_message(const constantPoolHandle& this_cp, int which, constantTag tag, oop pending_exception);
 858   static void save_and_throw_exception(const constantPoolHandle& this_cp, int which, constantTag tag, TRAPS);
 859 
 860  public:
 861   // Merging ConstantPool* support:
 862   bool compare_entry_to(int index1, const constantPoolHandle& cp2, int index2, TRAPS);
 863   void copy_cp_to(int start_i, int end_i, const constantPoolHandle& to_cp, int to_i, TRAPS) {
 864     constantPoolHandle h_this(THREAD, this);
 865     copy_cp_to_impl(h_this, start_i, end_i, to_cp, to_i, THREAD);
 866   }
 867   static void copy_cp_to_impl(const constantPoolHandle& from_cp, int start_i, int end_i, const constantPoolHandle& to_cp, int to_i, TRAPS);
 868   static void copy_entry_to(const constantPoolHandle& from_cp, int from_i, const constantPoolHandle& to_cp, int to_i, TRAPS);
 869   static void copy_operands(const constantPoolHandle& from_cp, const constantPoolHandle& to_cp, TRAPS);
 870   int  find_matching_entry(int pattern_i, const constantPoolHandle& search_cp, TRAPS);
 871   int  version() const                    { return _saved._version; }
 872   void set_version(int version)           { _saved._version = version; }
 873   void increment_and_save_version(int version) {
 874     _saved._version = version >= 0 ? (version + 1) : version;  // keep overflow
 875   }
 876 
 877   void set_resolved_reference_length(int length) { _saved._resolved_reference_length = length; }
 878   int  resolved_reference_length() const  { return _saved._resolved_reference_length; }
 879 
 880   // Decrease ref counts of symbols that are in the constant pool
 881   // when the holder class is unloaded
 882   void unreference_symbols();
 883 
 884   // Deallocate constant pool for RedefineClasses
 885   void deallocate_contents(ClassLoaderData* loader_data);
 886   void release_C_heap_structures();
 887 
 888   // JVMTI accesss - GetConstantPool, RetransformClasses, ...
 889   friend class JvmtiConstantPoolReconstituter;
 890 
 891  private:
 892   jint cpool_entry_size(jint idx);
 893   jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap);
 894 
 895   // Copy cpool bytes into byte array.
 896   // Returns:
 897   //  int > 0, count of the raw cpool bytes that have been copied
 898   //        0, OutOfMemory error
 899   //       -1, Internal error
 900   int  copy_cpool_bytes(int cpool_size,
 901                         SymbolHashMap* tbl,
 902                         unsigned char *bytes);
 903 
 904  public:
 905   // Verify
 906   void verify_on(outputStream* st);
 907 
 908   // Printing
 909   void print_on(outputStream* st) const;
 910   void print_value_on(outputStream* st) const;
 911   void print_entry_on(int index, outputStream* st);
 912 
 913   const char* internal_name() const { return "{constant pool}"; }
 914 
 915 #ifndef PRODUCT
 916   // Compile the world support
 917   static void preload_and_initialize_all_classes(ConstantPool* constant_pool, TRAPS);
 918 #endif
 919 };
 920 
 921 class SymbolHashMapEntry : public CHeapObj<mtSymbol> {
 922  private:
 923   unsigned int        _hash;   // 32-bit hash for item
 924   SymbolHashMapEntry* _next;   // Next element in the linked list for this bucket
 925   Symbol*             _symbol; // 1-st part of the mapping: symbol => value
 926   u2                  _value;  // 2-nd part of the mapping: symbol => value
 927 
 928  public:
 929   unsigned   int hash() const             { return _hash;   }
 930   void       set_hash(unsigned int hash)  { _hash = hash;   }
 931 
 932   SymbolHashMapEntry* next() const        { return _next;   }
 933   void set_next(SymbolHashMapEntry* next) { _next = next;   }
 934 
 935   Symbol*    symbol() const               { return _symbol; }
 936   void       set_symbol(Symbol* sym)      { _symbol = sym;  }
 937 
 938   u2         value() const                {  return _value; }
 939   void       set_value(u2 value)          { _value = value; }
 940 
 941   SymbolHashMapEntry(unsigned int hash, Symbol* symbol, u2 value)
 942     : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {}
 943 
 944 }; // End SymbolHashMapEntry class
 945 
 946 
 947 class SymbolHashMapBucket : public CHeapObj<mtSymbol> {
 948 
 949 private:
 950   SymbolHashMapEntry*    _entry;
 951 
 952 public:
 953   SymbolHashMapEntry* entry() const         {  return _entry; }
 954   void set_entry(SymbolHashMapEntry* entry) { _entry = entry; }
 955   void clear()                              { _entry = NULL;  }
 956 
 957 }; // End SymbolHashMapBucket class
 958 
 959 
 960 class SymbolHashMap: public CHeapObj<mtSymbol> {
 961 
 962  private:
 963   // Default number of entries in the table
 964   enum SymbolHashMap_Constants {
 965     _Def_HashMap_Size = 256
 966   };
 967 
 968   int                   _table_size;
 969   SymbolHashMapBucket*  _buckets;
 970 
 971   void initialize_table(int table_size) {
 972     _table_size = table_size;
 973     _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size, mtSymbol);
 974     for (int index = 0; index < table_size; index++) {
 975       _buckets[index].clear();
 976     }
 977   }
 978 
 979  public:
 980 
 981   int table_size() const        { return _table_size; }
 982 
 983   SymbolHashMap()               { initialize_table(_Def_HashMap_Size); }
 984   SymbolHashMap(int table_size) { initialize_table(table_size); }
 985 
 986   // hash P(31) from Kernighan & Ritchie
 987   static unsigned int compute_hash(const char* str, int len) {
 988     unsigned int hash = 0;
 989     while (len-- > 0) {
 990       hash = 31*hash + (unsigned) *str;
 991       str++;
 992     }
 993     return hash;
 994   }
 995 
 996   SymbolHashMapEntry* bucket(int i) {
 997     return _buckets[i].entry();
 998   }
 999 
1000   void add_entry(Symbol* sym, u2 value);
1001   SymbolHashMapEntry* find_entry(Symbol* sym);
1002 
1003   u2 symbol_to_value(Symbol* sym) {
1004     SymbolHashMapEntry *entry = find_entry(sym);
1005     return (entry == NULL) ? 0 : entry->value();
1006   }
1007 
1008   ~SymbolHashMap() {
1009     SymbolHashMapEntry* next;
1010     for (int i = 0; i < _table_size; i++) {
1011       for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) {
1012         next = cur->next();
1013         delete(cur);
1014       }
1015     }
1016     delete _buckets;
1017   }
1018 }; // End SymbolHashMap class
1019 
1020 #endif // SHARE_VM_OOPS_CONSTANTPOOLOOP_HPP