1 /*
   2  * Copyright (c) 1997, 2014, 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
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  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.
  22  *
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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   intptr_t _ptr;
  50  public:
  51   CPSlot(intptr_t ptr): _ptr(ptr) {}
  52   CPSlot(Klass* ptr): _ptr((intptr_t)ptr) {}
  53   CPSlot(Symbol* ptr): _ptr((intptr_t)ptr | 1) {}
  54 
  55   intptr_t value()   { return _ptr; }
  56   bool is_resolved()   { return (_ptr & 1) == 0; }
  57   bool is_unresolved() { return (_ptr & 1) == 1; }
  58 
  59   Symbol* get_symbol() {
  60     assert(is_unresolved(), "bad call");
  61     return (Symbol*)(_ptr & ~1);
  62   }
  63   Klass* get_klass() {
  64     assert(is_resolved(), "bad call");
  65     return (Klass*)_ptr;
  66   }
  67 };
  68 
  69 class KlassSizeStats;
  70 
  71 class ConstantPool : public Metadata {
  72   friend class VMStructs;
  73   friend class BytecodeInterpreter;  // Directly extracts a klass in the pool for fast instanceof/checkcast
  74   friend class Universe;             // For null constructor
  75  private:
  76   Array<u1>*           _tags;        // the tag array describing the constant pool's contents
  77   ConstantPoolCache*   _cache;       // the cache holding interpreter runtime information
  78   InstanceKlass*       _pool_holder; // the corresponding class
  79   Array<u2>*           _operands;    // for variable-sized (InvokeDynamic) nodes, usually empty
  80 
  81   // Array of resolved objects from the constant pool and map from resolved
  82   // object index to original constant pool index
  83   jobject              _resolved_references;
  84   Array<u2>*           _reference_map;
  85 
  86   enum {
  87     _has_preresolution = 1,           // Flags
  88     _on_stack          = 2
  89   };
  90 
  91   int                  _flags;  // old fashioned bit twiddling
  92   int                  _length; // number of elements in the array
  93 
  94   union {
  95     // set for CDS to restore resolved references
  96     int                _resolved_reference_length;
  97     // keeps version number for redefined classes (used in backtrace)
  98     int                _version;
  99   } _saved;
 100 
 101   void set_tags(Array<u1>* tags)               { _tags = tags; }
 102   void tag_at_put(int which, jbyte t)          { tags()->at_put(which, t); }
 103   void release_tag_at_put(int which, jbyte t)  { tags()->release_at_put(which, t); }
 104 
 105   u1* tag_addr_at(int which) const             { return tags()->adr_at(which); }
 106 
 107   void set_operands(Array<u2>* operands)       { _operands = operands; }
 108 
 109   int flags() const                            { return _flags; }
 110   void set_flags(int f)                        { _flags = f; }
 111 
 112  private:
 113   intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(ConstantPool)); }
 114 
 115   CPSlot slot_at(int which) {
 116     assert(is_within_bounds(which), "index out of bounds");
 117     // Uses volatile because the klass slot changes without a lock.
 118     volatile intptr_t adr = (intptr_t)OrderAccess::load_ptr_acquire(obj_at_addr_raw(which));
 119     assert(adr != 0 || which == 0, "cp entry for klass should not be zero");
 120     return CPSlot(adr);
 121   }
 122 
 123   void slot_at_put(int which, CPSlot s) const {
 124     assert(is_within_bounds(which), "index out of bounds");
 125     assert(s.value() != 0, "Caught something");
 126     *(intptr_t*)&base()[which] = s.value();
 127   }
 128   intptr_t* obj_at_addr_raw(int which) const {
 129     assert(is_within_bounds(which), "index out of bounds");
 130     return (intptr_t*) &base()[which];
 131   }
 132 
 133   jint* int_at_addr(int which) const {
 134     assert(is_within_bounds(which), "index out of bounds");
 135     return (jint*) &base()[which];
 136   }
 137 
 138   jlong* long_at_addr(int which) const {
 139     assert(is_within_bounds(which), "index out of bounds");
 140     return (jlong*) &base()[which];
 141   }
 142 
 143   jfloat* float_at_addr(int which) const {
 144     assert(is_within_bounds(which), "index out of bounds");
 145     return (jfloat*) &base()[which];
 146   }
 147 
 148   jdouble* double_at_addr(int which) const {
 149     assert(is_within_bounds(which), "index out of bounds");
 150     return (jdouble*) &base()[which];
 151   }
 152 
 153   ConstantPool(Array<u1>* tags);
 154   ConstantPool() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }
 155  public:
 156   static ConstantPool* allocate(ClassLoaderData* loader_data, int length, TRAPS);
 157 
 158   bool is_constantPool() const volatile     { return true; }
 159 
 160   Array<u1>* tags() const                   { return _tags; }
 161   Array<u2>* operands() const               { return _operands; }
 162 
 163   bool has_preresolution() const            { return (_flags & _has_preresolution) != 0; }
 164   void set_has_preresolution()              { _flags |= _has_preresolution; }
 165 
 166   // Redefine classes support.  If a method refering to this constant pool
 167   // is on the executing stack, or as a handle in vm code, this constant pool
 168   // can't be removed from the set of previous versions saved in the instance
 169   // class.
 170   bool on_stack() const                      { return (_flags &_on_stack) != 0; }
 171   void set_on_stack(const bool value);
 172 
 173   // Klass holding pool
 174   InstanceKlass* pool_holder() const      { return _pool_holder; }
 175   void set_pool_holder(InstanceKlass* k)  { _pool_holder = k; }
 176   InstanceKlass** pool_holder_addr()      { return &_pool_holder; }
 177 
 178   // Interpreter runtime support
 179   ConstantPoolCache* cache() const        { return _cache; }
 180   void set_cache(ConstantPoolCache* cache){ _cache = cache; }
 181 
 182   // Create object cache in the constant pool
 183   void initialize_resolved_references(ClassLoaderData* loader_data,
 184                                       intStack reference_map,
 185                                       int constant_pool_map_length,
 186                                       TRAPS);
 187 
 188   // resolved strings, methodHandles and callsite objects from the constant pool
 189   objArrayOop resolved_references()  const;
 190   // mapping resolved object array indexes to cp indexes and back.
 191   int object_to_cp_index(int index)         { return _reference_map->at(index); }
 192   int cp_to_object_index(int index);
 193 
 194   // Invokedynamic indexes.
 195   // They must look completely different from normal indexes.
 196   // The main reason is that byte swapping is sometimes done on normal indexes.
 197   // Finally, it is helpful for debugging to tell the two apart.
 198   static bool is_invokedynamic_index(int i) { return (i < 0); }
 199   static int  decode_invokedynamic_index(int i) { assert(is_invokedynamic_index(i),  ""); return ~i; }
 200   static int  encode_invokedynamic_index(int i) { assert(!is_invokedynamic_index(i), ""); return ~i; }
 201 
 202 
 203   // The invokedynamic points at a CP cache entry.  This entry points back
 204   // at the original CP entry (CONSTANT_InvokeDynamic) and also (via f2) at an entry
 205   // in the resolved_references array (which provides the appendix argument).
 206   int invokedynamic_cp_cache_index(int index) const {
 207     assert (is_invokedynamic_index(index), "should be a invokedynamic index");
 208     int cache_index = decode_invokedynamic_index(index);
 209     return cache_index;
 210   }
 211   ConstantPoolCacheEntry* invokedynamic_cp_cache_entry_at(int index) const {
 212     // decode index that invokedynamic points to.
 213     int cp_cache_index = invokedynamic_cp_cache_index(index);
 214     return cache()->entry_at(cp_cache_index);
 215   }
 216 
 217   // Assembly code support
 218   static int tags_offset_in_bytes()         { return offset_of(ConstantPool, _tags); }
 219   static int cache_offset_in_bytes()        { return offset_of(ConstantPool, _cache); }
 220   static int pool_holder_offset_in_bytes()  { return offset_of(ConstantPool, _pool_holder); }
 221   static int resolved_references_offset_in_bytes() { return offset_of(ConstantPool, _resolved_references); }
 222 
 223   // Storing constants
 224 
 225   void klass_at_put(int which, Klass* k) {
 226     assert(k != NULL, "resolved class shouldn't be null");
 227     assert(is_within_bounds(which), "index out of bounds");
 228     OrderAccess::release_store_ptr((Klass* volatile *)obj_at_addr_raw(which), k);
 229     // The interpreter assumes when the tag is stored, the klass is resolved
 230     // and the Klass* is a klass rather than a Symbol*, so we need
 231     // hardware store ordering here.
 232     release_tag_at_put(which, JVM_CONSTANT_Class);
 233   }
 234 
 235   // For temporary use while constructing constant pool
 236   void klass_index_at_put(int which, int name_index) {
 237     tag_at_put(which, JVM_CONSTANT_ClassIndex);
 238     *int_at_addr(which) = name_index;
 239   }
 240 
 241   // Temporary until actual use
 242   void unresolved_klass_at_put(int which, Symbol* s) {
 243     release_tag_at_put(which, JVM_CONSTANT_UnresolvedClass);
 244     slot_at_put(which, s);
 245   }
 246 
 247   void method_handle_index_at_put(int which, int ref_kind, int ref_index) {
 248     tag_at_put(which, JVM_CONSTANT_MethodHandle);
 249     *int_at_addr(which) = ((jint) ref_index<<16) | ref_kind;
 250   }
 251 
 252   void method_type_index_at_put(int which, int ref_index) {
 253     tag_at_put(which, JVM_CONSTANT_MethodType);
 254     *int_at_addr(which) = ref_index;
 255   }
 256 
 257   void invoke_dynamic_at_put(int which, int bootstrap_specifier_index, int name_and_type_index) {
 258     tag_at_put(which, JVM_CONSTANT_InvokeDynamic);
 259     *int_at_addr(which) = ((jint) name_and_type_index<<16) | bootstrap_specifier_index;
 260   }
 261 
 262   void unresolved_string_at_put(int which, Symbol* s) {
 263     release_tag_at_put(which, JVM_CONSTANT_String);
 264     *symbol_at_addr(which) = s;
 265   }
 266 
 267   void int_at_put(int which, jint i) {
 268     tag_at_put(which, JVM_CONSTANT_Integer);
 269     *int_at_addr(which) = i;
 270   }
 271 
 272   void long_at_put(int which, jlong l) {
 273     tag_at_put(which, JVM_CONSTANT_Long);
 274     // *long_at_addr(which) = l;
 275     Bytes::put_native_u8((address)long_at_addr(which), *((u8*) &l));
 276   }
 277 
 278   void float_at_put(int which, jfloat f) {
 279     tag_at_put(which, JVM_CONSTANT_Float);
 280     *float_at_addr(which) = f;
 281   }
 282 
 283   void double_at_put(int which, jdouble d) {
 284     tag_at_put(which, JVM_CONSTANT_Double);
 285     // *double_at_addr(which) = d;
 286     // u8 temp = *(u8*) &d;
 287     Bytes::put_native_u8((address) double_at_addr(which), *((u8*) &d));
 288   }
 289 
 290   Symbol** symbol_at_addr(int which) const {
 291     assert(is_within_bounds(which), "index out of bounds");
 292     return (Symbol**) &base()[which];
 293   }
 294 
 295   void symbol_at_put(int which, Symbol* s) {
 296     assert(s->refcount() != 0, "should have nonzero refcount");
 297     tag_at_put(which, JVM_CONSTANT_Utf8);
 298     *symbol_at_addr(which) = s;
 299   }
 300 
 301   void string_at_put(int which, int obj_index, oop str) {
 302     resolved_references()->obj_at_put(obj_index, str);
 303   }
 304 
 305   // For temporary use while constructing constant pool
 306   void string_index_at_put(int which, int string_index) {
 307     tag_at_put(which, JVM_CONSTANT_StringIndex);
 308     *int_at_addr(which) = string_index;
 309   }
 310 
 311   void field_at_put(int which, int class_index, int name_and_type_index) {
 312     tag_at_put(which, JVM_CONSTANT_Fieldref);
 313     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
 314   }
 315 
 316   void method_at_put(int which, int class_index, int name_and_type_index) {
 317     tag_at_put(which, JVM_CONSTANT_Methodref);
 318     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
 319   }
 320 
 321   void interface_method_at_put(int which, int class_index, int name_and_type_index) {
 322     tag_at_put(which, JVM_CONSTANT_InterfaceMethodref);
 323     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;  // Not so nice
 324   }
 325 
 326   void name_and_type_at_put(int which, int name_index, int signature_index) {
 327     tag_at_put(which, JVM_CONSTANT_NameAndType);
 328     *int_at_addr(which) = ((jint) signature_index<<16) | name_index;  // Not so nice
 329   }
 330 
 331   // Tag query
 332 
 333   constantTag tag_at(int which) const { return (constantTag)tags()->at_acquire(which); }
 334 
 335   // Fetching constants
 336 
 337   Klass* klass_at(int which, TRAPS) {
 338     constantPoolHandle h_this(THREAD, this);
 339     return klass_at_impl(h_this, which, true, CHECK_NULL);
 340   }
 341 
 342   // Version of klass_at that doesn't save the resolution error, called during deopt
 343   Klass* klass_at_ignore_error(int which, TRAPS) {
 344     constantPoolHandle h_this(THREAD, this);
 345     return klass_at_impl(h_this, which, false, CHECK_NULL);
 346   }
 347 
 348   Symbol* klass_name_at(int which);  // Returns the name, w/o resolving.
 349 
 350   Klass* resolved_klass_at(int which) const {  // Used by Compiler
 351     guarantee(tag_at(which).is_klass(), "Corrupted constant pool");
 352     // Must do an acquire here in case another thread resolved the klass
 353     // behind our back, lest we later load stale values thru the oop.
 354     return CPSlot((Klass*)OrderAccess::load_ptr_acquire(obj_at_addr_raw(which))).get_klass();
 355   }
 356 
 357   // RedefineClasses() API support:
 358   Symbol* klass_at_noresolve(int which) { return klass_name_at(which); }
 359 
 360   jint int_at(int which) {
 361     assert(tag_at(which).is_int(), "Corrupted constant pool");
 362     return *int_at_addr(which);
 363   }
 364 
 365   jlong long_at(int which) {
 366     assert(tag_at(which).is_long(), "Corrupted constant pool");
 367     // return *long_at_addr(which);
 368     u8 tmp = Bytes::get_native_u8((address)&base()[which]);
 369     return *((jlong*)&tmp);
 370   }
 371 
 372   jfloat float_at(int which) {
 373     assert(tag_at(which).is_float(), "Corrupted constant pool");
 374     return *float_at_addr(which);
 375   }
 376 
 377   jdouble double_at(int which) {
 378     assert(tag_at(which).is_double(), "Corrupted constant pool");
 379     u8 tmp = Bytes::get_native_u8((address)&base()[which]);
 380     return *((jdouble*)&tmp);
 381   }
 382 
 383   Symbol* symbol_at(int which) {
 384     assert(tag_at(which).is_utf8(), "Corrupted constant pool");
 385     return *symbol_at_addr(which);
 386   }
 387 
 388   oop string_at(int which, int obj_index, TRAPS) {
 389     constantPoolHandle h_this(THREAD, this);
 390     return string_at_impl(h_this, which, obj_index, THREAD);
 391   }
 392   oop string_at(int which, TRAPS) {
 393     int obj_index = cp_to_object_index(which);
 394     return string_at(which, obj_index, THREAD);
 395   }
 396 
 397   // Version that can be used before string oop array is created.
 398   oop uncached_string_at(int which, TRAPS);
 399 
 400   // A "pseudo-string" is an non-string oop that has found its way into
 401   // a String entry.
 402   // This can happen if the user patches a live
 403   // object into a CONSTANT_String entry of an anonymous class.
 404   // Method oops internally created for method handles may also
 405   // use pseudo-strings to link themselves to related metaobjects.
 406 
 407   bool is_pseudo_string_at(int which) {
 408     // A pseudo string is a string that doesn't have a symbol in the cpSlot
 409     return unresolved_string_at(which) == NULL;
 410   }
 411 
 412   oop pseudo_string_at(int which, int obj_index) {
 413     assert(tag_at(which).is_string(), "Corrupted constant pool");
 414     assert(unresolved_string_at(which) == NULL, "shouldn't have symbol");
 415     oop s = resolved_references()->obj_at(obj_index);
 416     return s;
 417   }
 418 
 419   oop pseudo_string_at(int which) {
 420     assert(tag_at(which).is_string(), "Corrupted constant pool");
 421     assert(unresolved_string_at(which) == NULL, "shouldn't have symbol");
 422     int obj_index = cp_to_object_index(which);
 423     oop s = resolved_references()->obj_at(obj_index);
 424     return s;
 425   }
 426 
 427   void pseudo_string_at_put(int which, int obj_index, oop x) {
 428     assert(tag_at(which).is_string(), "Corrupted constant pool");
 429     unresolved_string_at_put(which, NULL); // indicates patched string
 430     string_at_put(which, obj_index, x);    // this works just fine
 431   }
 432 
 433   // only called when we are sure a string entry is already resolved (via an
 434   // earlier string_at call.
 435   oop resolved_string_at(int which) {
 436     assert(tag_at(which).is_string(), "Corrupted constant pool");
 437     // Must do an acquire here in case another thread resolved the klass
 438     // behind our back, lest we later load stale values thru the oop.
 439     // we might want a volatile_obj_at in ObjArrayKlass.
 440     int obj_index = cp_to_object_index(which);
 441     return resolved_references()->obj_at(obj_index);
 442   }
 443 
 444   Symbol* unresolved_string_at(int which) {
 445     assert(tag_at(which).is_string(), "Corrupted constant pool");
 446     Symbol* s = *symbol_at_addr(which);
 447     return s;
 448   }
 449 
 450   // Returns an UTF8 for a CONSTANT_String entry at a given index.
 451   // UTF8 char* representation was chosen to avoid conversion of
 452   // java_lang_Strings at resolved entries into Symbol*s
 453   // or vice versa.
 454   // Caller is responsible for checking for pseudo-strings.
 455   char* string_at_noresolve(int which);
 456 
 457   jint name_and_type_at(int which) {
 458     assert(tag_at(which).is_name_and_type(), "Corrupted constant pool");
 459     return *int_at_addr(which);
 460   }
 461 
 462  private:
 463   int method_handle_ref_kind_at(int which, bool error_ok) {
 464     assert(tag_at(which).is_method_handle() ||
 465            (error_ok && tag_at(which).is_method_handle_in_error()), "Corrupted constant pool");
 466     return extract_low_short_from_int(*int_at_addr(which));  // mask out unwanted ref_index bits
 467   }
 468   int method_handle_index_at(int which, bool error_ok) {
 469     assert(tag_at(which).is_method_handle() ||
 470            (error_ok && tag_at(which).is_method_handle_in_error()), "Corrupted constant pool");
 471     return extract_high_short_from_int(*int_at_addr(which));  // shift out unwanted ref_kind bits
 472   }
 473   int method_type_index_at(int which, bool error_ok) {
 474     assert(tag_at(which).is_method_type() ||
 475            (error_ok && tag_at(which).is_method_type_in_error()), "Corrupted constant pool");
 476     return *int_at_addr(which);
 477   }
 478  public:
 479   int method_handle_ref_kind_at(int which) {
 480     return method_handle_ref_kind_at(which, false);
 481   }
 482   int method_handle_ref_kind_at_error_ok(int which) {
 483     return method_handle_ref_kind_at(which, true);
 484   }
 485   int method_handle_index_at(int which) {
 486     return method_handle_index_at(which, false);
 487   }
 488   int method_handle_index_at_error_ok(int which) {
 489     return method_handle_index_at(which, true);
 490   }
 491   int method_type_index_at(int which) {
 492     return method_type_index_at(which, false);
 493   }
 494   int method_type_index_at_error_ok(int which) {
 495     return method_type_index_at(which, true);
 496   }
 497 
 498   // Derived queries:
 499   Symbol* method_handle_name_ref_at(int which) {
 500     int member = method_handle_index_at(which);
 501     return impl_name_ref_at(member, true);
 502   }
 503   Symbol* method_handle_signature_ref_at(int which) {
 504     int member = method_handle_index_at(which);
 505     return impl_signature_ref_at(member, true);
 506   }
 507   int method_handle_klass_index_at(int which) {
 508     int member = method_handle_index_at(which);
 509     return impl_klass_ref_index_at(member, true);
 510   }
 511   Symbol* method_type_signature_at(int which) {
 512     int sym = method_type_index_at(which);
 513     return symbol_at(sym);
 514   }
 515 
 516   int invoke_dynamic_name_and_type_ref_index_at(int which) {
 517     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 518     return extract_high_short_from_int(*int_at_addr(which));
 519   }
 520   int invoke_dynamic_bootstrap_specifier_index(int which) {
 521     assert(tag_at(which).value() == JVM_CONSTANT_InvokeDynamic, "Corrupted constant pool");
 522     return extract_low_short_from_int(*int_at_addr(which));
 523   }
 524   int invoke_dynamic_operand_base(int which) {
 525     int bootstrap_specifier_index = invoke_dynamic_bootstrap_specifier_index(which);
 526     return operand_offset_at(operands(), bootstrap_specifier_index);
 527   }
 528   // The first part of the operands array consists of an index into the second part.
 529   // Extract a 32-bit index value from the first part.
 530   static int operand_offset_at(Array<u2>* operands, int bootstrap_specifier_index) {
 531     int n = (bootstrap_specifier_index * 2);
 532     assert(n >= 0 && n+2 <= operands->length(), "oob");
 533     // The first 32-bit index points to the beginning of the second part
 534     // of the operands array.  Make sure this index is in the first part.
 535     DEBUG_ONLY(int second_part = build_int_from_shorts(operands->at(0),
 536                                                        operands->at(1)));
 537     assert(second_part == 0 || n+2 <= second_part, "oob (2)");
 538     int offset = build_int_from_shorts(operands->at(n+0),
 539                                        operands->at(n+1));
 540     // The offset itself must point into the second part of the array.
 541     assert(offset == 0 || offset >= second_part && offset <= operands->length(), "oob (3)");
 542     return offset;
 543   }
 544   static void operand_offset_at_put(Array<u2>* operands, int bootstrap_specifier_index, int offset) {
 545     int n = bootstrap_specifier_index * 2;
 546     assert(n >= 0 && n+2 <= operands->length(), "oob");
 547     operands->at_put(n+0, extract_low_short_from_int(offset));
 548     operands->at_put(n+1, extract_high_short_from_int(offset));
 549   }
 550   static int operand_array_length(Array<u2>* operands) {
 551     if (operands == NULL || operands->length() == 0)  return 0;
 552     int second_part = operand_offset_at(operands, 0);
 553     return (second_part / 2);
 554   }
 555 
 556 #ifdef ASSERT
 557   // operand tuples fit together exactly, end to end
 558   static int operand_limit_at(Array<u2>* operands, int bootstrap_specifier_index) {
 559     int nextidx = bootstrap_specifier_index + 1;
 560     if (nextidx == operand_array_length(operands))
 561       return operands->length();
 562     else
 563       return operand_offset_at(operands, nextidx);
 564   }
 565   int invoke_dynamic_operand_limit(int which) {
 566     int bootstrap_specifier_index = invoke_dynamic_bootstrap_specifier_index(which);
 567     return operand_limit_at(operands(), bootstrap_specifier_index);
 568   }
 569 #endif //ASSERT
 570 
 571   // layout of InvokeDynamic bootstrap method specifier (in second part of operands array):
 572   enum {
 573          _indy_bsm_offset  = 0,  // CONSTANT_MethodHandle bsm
 574          _indy_argc_offset = 1,  // u2 argc
 575          _indy_argv_offset = 2   // u2 argv[argc]
 576   };
 577 
 578   // These functions are used in RedefineClasses for CP merge
 579 
 580   int operand_offset_at(int bootstrap_specifier_index) {
 581     assert(0 <= bootstrap_specifier_index &&
 582            bootstrap_specifier_index < operand_array_length(operands()),
 583            "Corrupted CP operands");
 584     return operand_offset_at(operands(), bootstrap_specifier_index);
 585   }
 586   int operand_bootstrap_method_ref_index_at(int bootstrap_specifier_index) {
 587     int offset = operand_offset_at(bootstrap_specifier_index);
 588     return operands()->at(offset + _indy_bsm_offset);
 589   }
 590   int operand_argument_count_at(int bootstrap_specifier_index) {
 591     int offset = operand_offset_at(bootstrap_specifier_index);
 592     int argc = operands()->at(offset + _indy_argc_offset);
 593     return argc;
 594   }
 595   int operand_argument_index_at(int bootstrap_specifier_index, int j) {
 596     int offset = operand_offset_at(bootstrap_specifier_index);
 597     return operands()->at(offset + _indy_argv_offset + j);
 598   }
 599   int operand_next_offset_at(int bootstrap_specifier_index) {
 600     int offset = operand_offset_at(bootstrap_specifier_index) + _indy_argv_offset
 601                    + operand_argument_count_at(bootstrap_specifier_index);
 602     return offset;
 603   }
 604   // Compare a bootsrap specifier in the operands arrays
 605   bool compare_operand_to(int bootstrap_specifier_index1, constantPoolHandle cp2,
 606                           int bootstrap_specifier_index2, TRAPS);
 607   // Find a bootsrap specifier in the operands array
 608   int find_matching_operand(int bootstrap_specifier_index, constantPoolHandle search_cp,
 609                             int operands_cur_len, TRAPS);
 610   // Resize the operands array with delta_len and delta_size
 611   void resize_operands(int delta_len, int delta_size, TRAPS);
 612   // Extend the operands array with the length and size of the ext_cp operands
 613   void extend_operands(constantPoolHandle ext_cp, TRAPS);
 614   // Shrink the operands array to a smaller array with new_len length
 615   void shrink_operands(int new_len, TRAPS);
 616 
 617 
 618   int invoke_dynamic_bootstrap_method_ref_index_at(int which) {
 619     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 620     int op_base = invoke_dynamic_operand_base(which);
 621     return operands()->at(op_base + _indy_bsm_offset);
 622   }
 623   int invoke_dynamic_argument_count_at(int which) {
 624     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 625     int op_base = invoke_dynamic_operand_base(which);
 626     int argc = operands()->at(op_base + _indy_argc_offset);
 627     DEBUG_ONLY(int end_offset = op_base + _indy_argv_offset + argc;
 628                int next_offset = invoke_dynamic_operand_limit(which));
 629     assert(end_offset == next_offset, "matched ending");
 630     return argc;
 631   }
 632   int invoke_dynamic_argument_index_at(int which, int j) {
 633     int op_base = invoke_dynamic_operand_base(which);
 634     DEBUG_ONLY(int argc = operands()->at(op_base + _indy_argc_offset));
 635     assert((uint)j < (uint)argc, "oob");
 636     return operands()->at(op_base + _indy_argv_offset + j);
 637   }
 638 
 639   // The following methods (name/signature/klass_ref_at, klass_ref_at_noresolve,
 640   // name_and_type_ref_index_at) all expect to be passed indices obtained
 641   // directly from the bytecode.
 642   // If the indices are meant to refer to fields or methods, they are
 643   // actually rewritten constant pool cache indices.
 644   // The routine remap_instruction_operand_from_cache manages the adjustment
 645   // of these values back to constant pool indices.
 646 
 647   // There are also "uncached" versions which do not adjust the operand index; see below.
 648 
 649   // FIXME: Consider renaming these with a prefix "cached_" to make the distinction clear.
 650   // In a few cases (the verifier) there are uses before a cpcache has been built,
 651   // which are handled by a dynamic check in remap_instruction_operand_from_cache.
 652   // FIXME: Remove the dynamic check, and adjust all callers to specify the correct mode.
 653 
 654   // Lookup for entries consisting of (klass_index, name_and_type index)
 655   Klass* klass_ref_at(int which, TRAPS);
 656   Symbol* klass_ref_at_noresolve(int which);
 657   Symbol* name_ref_at(int which)                { return impl_name_ref_at(which, false); }
 658   Symbol* signature_ref_at(int which)           { return impl_signature_ref_at(which, false); }
 659 
 660   int klass_ref_index_at(int which)               { return impl_klass_ref_index_at(which, false); }
 661   int name_and_type_ref_index_at(int which)       { return impl_name_and_type_ref_index_at(which, false); }
 662 
 663   // Lookup for entries consisting of (name_index, signature_index)
 664   int name_ref_index_at(int which_nt);            // ==  low-order jshort of name_and_type_at(which_nt)
 665   int signature_ref_index_at(int which_nt);       // == high-order jshort of name_and_type_at(which_nt)
 666 
 667   BasicType basic_type_for_signature_at(int which);
 668 
 669   // Resolve string constants (to prevent allocation during compilation)
 670   void resolve_string_constants(TRAPS) {
 671     constantPoolHandle h_this(THREAD, this);
 672     resolve_string_constants_impl(h_this, CHECK);
 673   }
 674 
 675   // CDS support
 676   void remove_unshareable_info();
 677   void restore_unshareable_info(TRAPS);
 678   bool resolve_class_constants(TRAPS);
 679   // The ConstantPool vtable is restored by this call when the ConstantPool is
 680   // in the shared archive.  See patch_klass_vtables() in metaspaceShared.cpp for
 681   // all the gory details.  SA, dtrace and pstack helpers distinguish metadata
 682   // by their vtable.
 683   void restore_vtable() { guarantee(is_constantPool(), "vtable restored by this call"); }
 684 
 685  private:
 686   enum { _no_index_sentinel = -1, _possible_index_sentinel = -2 };
 687  public:
 688 
 689   // Resolve late bound constants.
 690   oop resolve_constant_at(int index, TRAPS) {
 691     constantPoolHandle h_this(THREAD, this);
 692     return resolve_constant_at_impl(h_this, index, _no_index_sentinel, THREAD);
 693   }
 694 
 695   oop resolve_cached_constant_at(int cache_index, TRAPS) {
 696     constantPoolHandle h_this(THREAD, this);
 697     return resolve_constant_at_impl(h_this, _no_index_sentinel, cache_index, THREAD);
 698   }
 699 
 700   oop resolve_possibly_cached_constant_at(int pool_index, TRAPS) {
 701     constantPoolHandle h_this(THREAD, this);
 702     return resolve_constant_at_impl(h_this, pool_index, _possible_index_sentinel, THREAD);
 703   }
 704 
 705   oop resolve_bootstrap_specifier_at(int index, TRAPS) {
 706     constantPoolHandle h_this(THREAD, this);
 707     return resolve_bootstrap_specifier_at_impl(h_this, index, THREAD);
 708   }
 709 
 710   // Klass name matches name at offset
 711   bool klass_name_at_matches(instanceKlassHandle k, int which);
 712 
 713   // Sizing
 714   int length() const                   { return _length; }
 715   void set_length(int length)          { _length = length; }
 716 
 717   // Tells whether index is within bounds.
 718   bool is_within_bounds(int index) const {
 719     return 0 <= index && index < length();
 720   }
 721 
 722   // Sizing (in words)
 723   static int header_size()             { return sizeof(ConstantPool)/HeapWordSize; }
 724   static int size(int length)          { return align_object_size(header_size() + length); }
 725   int size() const                     { return size(length()); }
 726 #if INCLUDE_SERVICES
 727   void collect_statistics(KlassSizeStats *sz) const;
 728 #endif
 729 
 730   friend class ClassFileParser;
 731   friend class SystemDictionary;
 732 
 733   // Used by compiler to prevent classloading.
 734   static Method*          method_at_if_loaded      (constantPoolHandle this_cp, int which);
 735   static bool       has_appendix_at_if_loaded      (constantPoolHandle this_cp, int which);
 736   static oop            appendix_at_if_loaded      (constantPoolHandle this_cp, int which);
 737   static bool    has_method_type_at_if_loaded      (constantPoolHandle this_cp, int which);
 738   static oop         method_type_at_if_loaded      (constantPoolHandle this_cp, int which);
 739   static Klass*            klass_at_if_loaded      (constantPoolHandle this_cp, int which);
 740   static Klass*        klass_ref_at_if_loaded      (constantPoolHandle this_cp, int which);
 741 
 742   // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the
 743   // future by other Java code. These take constant pool indices rather than
 744   // constant pool cache indices as do the peer methods above.
 745   Symbol* uncached_klass_ref_at_noresolve(int which);
 746   Symbol* uncached_name_ref_at(int which)                 { return impl_name_ref_at(which, true); }
 747   Symbol* uncached_signature_ref_at(int which)            { return impl_signature_ref_at(which, true); }
 748   int       uncached_klass_ref_index_at(int which)          { return impl_klass_ref_index_at(which, true); }
 749   int       uncached_name_and_type_ref_index_at(int which)  { return impl_name_and_type_ref_index_at(which, true); }
 750 
 751   // Sharing
 752   int pre_resolve_shared_klasses(TRAPS);
 753 
 754   // Debugging
 755   const char* printable_name_at(int which) PRODUCT_RETURN0;
 756 
 757 #ifdef ASSERT
 758   enum { CPCACHE_INDEX_TAG = 0x10000 };  // helps keep CP cache indices distinct from CP indices
 759 #else
 760   enum { CPCACHE_INDEX_TAG = 0 };        // in product mode, this zero value is a no-op
 761 #endif //ASSERT
 762 
 763   static int decode_cpcache_index(int raw_index, bool invokedynamic_ok = false) {
 764     if (invokedynamic_ok && is_invokedynamic_index(raw_index))
 765       return decode_invokedynamic_index(raw_index);
 766     else
 767       return raw_index - CPCACHE_INDEX_TAG;
 768   }
 769 
 770  private:
 771 
 772   void set_resolved_references(jobject s) { _resolved_references = s; }
 773   Array<u2>* reference_map() const        { return _reference_map; }
 774   void set_reference_map(Array<u2>* o)    { _reference_map = o; }
 775 
 776   // patch JSR 292 resolved references after the class is linked.
 777   void patch_resolved_references(GrowableArray<Handle>* cp_patches);
 778 
 779   Symbol* impl_name_ref_at(int which, bool uncached);
 780   Symbol* impl_signature_ref_at(int which, bool uncached);
 781   int       impl_klass_ref_index_at(int which, bool uncached);
 782   int       impl_name_and_type_ref_index_at(int which, bool uncached);
 783 
 784   int remap_instruction_operand_from_cache(int operand);  // operand must be biased by CPCACHE_INDEX_TAG
 785 
 786   // Used while constructing constant pool (only by ClassFileParser)
 787   jint klass_index_at(int which) {
 788     assert(tag_at(which).is_klass_index(), "Corrupted constant pool");
 789     return *int_at_addr(which);
 790   }
 791 
 792   jint string_index_at(int which) {
 793     assert(tag_at(which).is_string_index(), "Corrupted constant pool");
 794     return *int_at_addr(which);
 795   }
 796 
 797   // Performs the LinkResolver checks
 798   static void verify_constant_pool_resolve(constantPoolHandle this_cp, KlassHandle klass, TRAPS);
 799 
 800   // Implementation of methods that needs an exposed 'this' pointer, in order to
 801   // handle GC while executing the method
 802   static Klass* klass_at_impl(constantPoolHandle this_cp, int which,
 803                               bool save_resolution_error, TRAPS);
 804   static oop string_at_impl(constantPoolHandle this_cp, int which, int obj_index, TRAPS);
 805 
 806   static void trace_class_resolution(constantPoolHandle this_cp, KlassHandle k);
 807 
 808   // Resolve string constants (to prevent allocation during compilation)
 809   static void resolve_string_constants_impl(constantPoolHandle this_cp, TRAPS);
 810 
 811   static oop resolve_constant_at_impl(constantPoolHandle this_cp, int index, int cache_index, TRAPS);
 812   static oop resolve_bootstrap_specifier_at_impl(constantPoolHandle this_cp, int index, TRAPS);
 813 
 814   // Exception handling
 815   static void throw_resolution_error(constantPoolHandle this_cp, int which, TRAPS);
 816   static Symbol* exception_message(constantPoolHandle this_cp, int which, constantTag tag, oop pending_exception);
 817   static void save_and_throw_exception(constantPoolHandle this_cp, int which, constantTag tag, TRAPS);
 818 
 819  public:
 820   // Merging ConstantPool* support:
 821   bool compare_entry_to(int index1, constantPoolHandle cp2, int index2, TRAPS);
 822   void copy_cp_to(int start_i, int end_i, constantPoolHandle to_cp, int to_i, TRAPS) {
 823     constantPoolHandle h_this(THREAD, this);
 824     copy_cp_to_impl(h_this, start_i, end_i, to_cp, to_i, THREAD);
 825   }
 826   static void copy_cp_to_impl(constantPoolHandle from_cp, int start_i, int end_i, constantPoolHandle to_cp, int to_i, TRAPS);
 827   static void copy_entry_to(constantPoolHandle from_cp, int from_i, constantPoolHandle to_cp, int to_i, TRAPS);
 828   static void copy_operands(constantPoolHandle from_cp, constantPoolHandle to_cp, TRAPS);
 829   int  find_matching_entry(int pattern_i, constantPoolHandle search_cp, TRAPS);
 830   int  version() const                    { return _saved._version; }
 831   void set_version(int version)           { _saved._version = version; }
 832   void increment_and_save_version(int version) {
 833     _saved._version = version >= 0 ? (version + 1) : version;  // keep overflow
 834   }
 835 
 836   void set_resolved_reference_length(int length) { _saved._resolved_reference_length = length; }
 837   int  resolved_reference_length() const  { return _saved._resolved_reference_length; }
 838 
 839   // Decrease ref counts of symbols that are in the constant pool
 840   // when the holder class is unloaded
 841   void unreference_symbols();
 842 
 843   // Deallocate constant pool for RedefineClasses
 844   void deallocate_contents(ClassLoaderData* loader_data);
 845   void release_C_heap_structures();
 846 
 847   // JVMTI accesss - GetConstantPool, RetransformClasses, ...
 848   friend class JvmtiConstantPoolReconstituter;
 849 
 850  private:
 851   jint cpool_entry_size(jint idx);
 852   jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap);
 853 
 854   // Copy cpool bytes into byte array.
 855   // Returns:
 856   //  int > 0, count of the raw cpool bytes that have been copied
 857   //        0, OutOfMemory error
 858   //       -1, Internal error
 859   int  copy_cpool_bytes(int cpool_size,
 860                         SymbolHashMap* tbl,
 861                         unsigned char *bytes);
 862 
 863  public:
 864   // Verify
 865   void verify_on(outputStream* st);
 866 
 867   // Printing
 868   void print_on(outputStream* st) const;
 869   void print_value_on(outputStream* st) const;
 870   void print_entry_on(int index, outputStream* st);
 871 
 872   const char* internal_name() const { return "{constant pool}"; }
 873 
 874 #ifndef PRODUCT
 875   // Compile the world support
 876   static void preload_and_initialize_all_classes(ConstantPool* constant_pool, TRAPS);
 877 #endif
 878 };
 879 
 880 class SymbolHashMapEntry : public CHeapObj<mtSymbol> {
 881  private:
 882   unsigned int        _hash;   // 32-bit hash for item
 883   SymbolHashMapEntry* _next;   // Next element in the linked list for this bucket
 884   Symbol*             _symbol; // 1-st part of the mapping: symbol => value
 885   u2                  _value;  // 2-nd part of the mapping: symbol => value
 886 
 887  public:
 888   unsigned   int hash() const             { return _hash;   }
 889   void       set_hash(unsigned int hash)  { _hash = hash;   }
 890 
 891   SymbolHashMapEntry* next() const        { return _next;   }
 892   void set_next(SymbolHashMapEntry* next) { _next = next;   }
 893 
 894   Symbol*    symbol() const               { return _symbol; }
 895   void       set_symbol(Symbol* sym)      { _symbol = sym;  }
 896 
 897   u2         value() const                {  return _value; }
 898   void       set_value(u2 value)          { _value = value; }
 899 
 900   SymbolHashMapEntry(unsigned int hash, Symbol* symbol, u2 value)
 901     : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {}
 902 
 903 }; // End SymbolHashMapEntry class
 904 
 905 
 906 class SymbolHashMapBucket : public CHeapObj<mtSymbol> {
 907 
 908 private:
 909   SymbolHashMapEntry*    _entry;
 910 
 911 public:
 912   SymbolHashMapEntry* entry() const         {  return _entry; }
 913   void set_entry(SymbolHashMapEntry* entry) { _entry = entry; }
 914   void clear()                              { _entry = NULL;  }
 915 
 916 }; // End SymbolHashMapBucket class
 917 
 918 
 919 class SymbolHashMap: public CHeapObj<mtSymbol> {
 920 
 921  private:
 922   // Default number of entries in the table
 923   enum SymbolHashMap_Constants {
 924     _Def_HashMap_Size = 256
 925   };
 926 
 927   int                   _table_size;
 928   SymbolHashMapBucket*  _buckets;
 929 
 930   void initialize_table(int table_size) {
 931     _table_size = table_size;
 932     _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size, mtSymbol);
 933     for (int index = 0; index < table_size; index++) {
 934       _buckets[index].clear();
 935     }
 936   }
 937 
 938  public:
 939 
 940   int table_size() const        { return _table_size; }
 941 
 942   SymbolHashMap()               { initialize_table(_Def_HashMap_Size); }
 943   SymbolHashMap(int table_size) { initialize_table(table_size); }
 944 
 945   // hash P(31) from Kernighan & Ritchie
 946   static unsigned int compute_hash(const char* str, int len) {
 947     unsigned int hash = 0;
 948     while (len-- > 0) {
 949       hash = 31*hash + (unsigned) *str;
 950       str++;
 951     }
 952     return hash;
 953   }
 954 
 955   SymbolHashMapEntry* bucket(int i) {
 956     return _buckets[i].entry();
 957   }
 958 
 959   void add_entry(Symbol* sym, u2 value);
 960   SymbolHashMapEntry* find_entry(Symbol* sym);
 961 
 962   u2 symbol_to_value(Symbol* sym) {
 963     SymbolHashMapEntry *entry = find_entry(sym);
 964     return (entry == NULL) ? 0 : entry->value();
 965   }
 966 
 967   ~SymbolHashMap() {
 968     SymbolHashMapEntry* next;
 969     for (int i = 0; i < _table_size; i++) {
 970       for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) {
 971         next = cur->next();
 972         delete(cur);
 973       }
 974     }
 975     delete _buckets;
 976   }
 977 }; // End SymbolHashMap class
 978 
 979 #endif // SHARE_VM_OOPS_CONSTANTPOOLOOP_HPP