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  *
  23  */
  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   // Needed for JvmtiConstantPoolReconstituter.
  87   // Map from a pseudo-string index to the original Utf8 entry index.
  88   // Each u4 entry consist of two packed u2 integers:
  89   //   JVM_CONSTANT_String index and JVM_CONSTANT_Utf8 index
  90   GrowableArray<u4>*   _pseudo_string_map;
  91 
  92   enum {
  93     _has_preresolution = 1,           // Flags
  94     _on_stack          = 2
  95   };
  96 
  97   int                  _flags;  // old fashioned bit twiddling
  98   int                  _length; // number of elements in the array
  99 
 100   union {
 101     // set for CDS to restore resolved references
 102     int                _resolved_reference_length;
 103     // keeps version number for redefined classes (used in backtrace)
 104     int                _version;
 105   } _saved;
 106 
 107   void set_tags(Array<u1>* tags)               { _tags = tags; }
 108   void tag_at_put(int which, jbyte t)          { tags()->at_put(which, t); }
 109   void release_tag_at_put(int which, jbyte t)  { tags()->release_at_put(which, t); }
 110 
 111   u1* tag_addr_at(int which) const             { return tags()->adr_at(which); }
 112 
 113   void set_operands(Array<u2>* operands)       { _operands = operands; }
 114 
 115   int flags() const                            { return _flags; }
 116   void set_flags(int f)                        { _flags = f; }
 117 
 118  private:
 119   intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(ConstantPool)); }
 120 
 121   CPSlot slot_at(int which) {
 122     assert(is_within_bounds(which), "index out of bounds");
 123     // Uses volatile because the klass slot changes without a lock.
 124     volatile intptr_t adr = (intptr_t)OrderAccess::load_ptr_acquire(obj_at_addr_raw(which));
 125     assert(adr != 0 || which == 0, "cp entry for klass should not be zero");
 126     return CPSlot(adr);
 127   }
 128 
 129   void slot_at_put(int which, CPSlot s) const {
 130     assert(is_within_bounds(which), "index out of bounds");
 131     assert(s.value() != 0, "Caught something");
 132     *(intptr_t*)&base()[which] = s.value();
 133   }
 134   intptr_t* obj_at_addr_raw(int which) const {
 135     assert(is_within_bounds(which), "index out of bounds");
 136     return (intptr_t*) &base()[which];
 137   }
 138 
 139   jint* int_at_addr(int which) const {
 140     assert(is_within_bounds(which), "index out of bounds");
 141     return (jint*) &base()[which];
 142   }
 143 
 144   jlong* long_at_addr(int which) const {
 145     assert(is_within_bounds(which), "index out of bounds");
 146     return (jlong*) &base()[which];
 147   }
 148 
 149   jfloat* float_at_addr(int which) const {
 150     assert(is_within_bounds(which), "index out of bounds");
 151     return (jfloat*) &base()[which];
 152   }
 153 
 154   jdouble* double_at_addr(int which) const {
 155     assert(is_within_bounds(which), "index out of bounds");
 156     return (jdouble*) &base()[which];
 157   }
 158 
 159   ConstantPool(Array<u1>* tags);
 160   ConstantPool() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }
 161  public:
 162   static ConstantPool* allocate(ClassLoaderData* loader_data, int length, TRAPS);
 163 
 164   bool is_constantPool() const volatile     { return true; }
 165 
 166   Array<u1>* tags() const                   { return _tags; }
 167   Array<u2>* operands() const               { return _operands; }
 168 
 169   GrowableArray<u4>* pseudo_string_map() {
 170     if (_pseudo_string_map == NULL) {
 171       _pseudo_string_map = new(ResourceObj::C_HEAP, mtClass) GrowableArray<u4>(1, true);
 172     }
 173     return _pseudo_string_map;
 174   }
 175 
 176   void map_pseudo_string_indices(u2 index, u2 utf8_idx) {
 177     u4 packed = index << 16 | utf8_idx;
 178     pseudo_string_map()->append(packed);
 179   }
 180 
 181   u2 get_pseudo_string_utf8_index(u2 index) {
 182     GrowableArray<u4>* map = pseudo_string_map();
 183     int len = map->length();
 184     // The entries are ordered by value so that a binary search can be
 185     // used if a performance bottleneck is observed in this area.
 186     for (int i = 0; i < len; i++) {
 187       u4 packed = map->at(i);
 188       u2 idx = (packed >> 16) & 0xFF;
 189       if (idx == index) {
 190         u2 utf8_idx = packed & 0xFF;
 191         assert(utf8_idx > 0, "Utf8 cp index in pseudo-string map must be positive");
 192         return utf8_idx;
 193       }
 194     }
 195     assert(true, "not found a matching entry in pseudo-string map");
 196     return 0;
 197   }
 198 
 199   bool has_preresolution() const            { return (_flags & _has_preresolution) != 0; }
 200   void set_has_preresolution()              { _flags |= _has_preresolution; }
 201 
 202   // Redefine classes support.  If a method refering to this constant pool
 203   // is on the executing stack, or as a handle in vm code, this constant pool
 204   // can't be removed from the set of previous versions saved in the instance
 205   // class.
 206   bool on_stack() const                      { return (_flags &_on_stack) != 0; }
 207   void set_on_stack(const bool value);
 208 
 209   // Klass holding pool
 210   InstanceKlass* pool_holder() const      { return _pool_holder; }
 211   void set_pool_holder(InstanceKlass* k)  { _pool_holder = k; }
 212   InstanceKlass** pool_holder_addr()      { return &_pool_holder; }
 213 
 214   // Interpreter runtime support
 215   ConstantPoolCache* cache() const        { return _cache; }
 216   void set_cache(ConstantPoolCache* cache){ _cache = cache; }
 217 
 218   // Create object cache in the constant pool
 219   void initialize_resolved_references(ClassLoaderData* loader_data,
 220                                       intStack reference_map,
 221                                       int constant_pool_map_length,
 222                                       TRAPS);
 223 
 224   // resolved strings, methodHandles and callsite objects from the constant pool
 225   objArrayOop resolved_references()  const;
 226   // mapping resolved object array indexes to cp indexes and back.
 227   int object_to_cp_index(int index)         { return _reference_map->at(index); }
 228   int cp_to_object_index(int index);
 229 
 230   // Invokedynamic indexes.
 231   // They must look completely different from normal indexes.
 232   // The main reason is that byte swapping is sometimes done on normal indexes.
 233   // Finally, it is helpful for debugging to tell the two apart.
 234   static bool is_invokedynamic_index(int i) { return (i < 0); }
 235   static int  decode_invokedynamic_index(int i) { assert(is_invokedynamic_index(i),  ""); return ~i; }
 236   static int  encode_invokedynamic_index(int i) { assert(!is_invokedynamic_index(i), ""); return ~i; }
 237 
 238 
 239   // The invokedynamic points at a CP cache entry.  This entry points back
 240   // at the original CP entry (CONSTANT_InvokeDynamic) and also (via f2) at an entry
 241   // in the resolved_references array (which provides the appendix argument).
 242   int invokedynamic_cp_cache_index(int index) const {
 243     assert (is_invokedynamic_index(index), "should be a invokedynamic index");
 244     int cache_index = decode_invokedynamic_index(index);
 245     return cache_index;
 246   }
 247   ConstantPoolCacheEntry* invokedynamic_cp_cache_entry_at(int index) const {
 248     // decode index that invokedynamic points to.
 249     int cp_cache_index = invokedynamic_cp_cache_index(index);
 250     return cache()->entry_at(cp_cache_index);
 251   }
 252 
 253   // Assembly code support
 254   static int tags_offset_in_bytes()         { return offset_of(ConstantPool, _tags); }
 255   static int cache_offset_in_bytes()        { return offset_of(ConstantPool, _cache); }
 256   static int pool_holder_offset_in_bytes()  { return offset_of(ConstantPool, _pool_holder); }
 257   static int resolved_references_offset_in_bytes() { return offset_of(ConstantPool, _resolved_references); }
 258 
 259   // Storing constants
 260 
 261   void klass_at_put(int which, Klass* k) {
 262     assert(k != NULL, "resolved class shouldn't be null");
 263     assert(is_within_bounds(which), "index out of bounds");
 264     OrderAccess::release_store_ptr((Klass* volatile *)obj_at_addr_raw(which), k);
 265     // The interpreter assumes when the tag is stored, the klass is resolved
 266     // and the Klass* is a klass rather than a Symbol*, so we need
 267     // hardware store ordering here.
 268     release_tag_at_put(which, JVM_CONSTANT_Class);
 269   }
 270 
 271   // For temporary use while constructing constant pool
 272   void klass_index_at_put(int which, int name_index) {
 273     tag_at_put(which, JVM_CONSTANT_ClassIndex);
 274     *int_at_addr(which) = name_index;
 275   }
 276 
 277   // Temporary until actual use
 278   void unresolved_klass_at_put(int which, Symbol* s) {
 279     release_tag_at_put(which, JVM_CONSTANT_UnresolvedClass);
 280     slot_at_put(which, s);
 281   }
 282 
 283   void method_handle_index_at_put(int which, int ref_kind, int ref_index) {
 284     tag_at_put(which, JVM_CONSTANT_MethodHandle);
 285     *int_at_addr(which) = ((jint) ref_index<<16) | ref_kind;
 286   }
 287 
 288   void method_type_index_at_put(int which, int ref_index) {
 289     tag_at_put(which, JVM_CONSTANT_MethodType);
 290     *int_at_addr(which) = ref_index;
 291   }
 292 
 293   void invoke_dynamic_at_put(int which, int bootstrap_specifier_index, int name_and_type_index) {
 294     tag_at_put(which, JVM_CONSTANT_InvokeDynamic);
 295     *int_at_addr(which) = ((jint) name_and_type_index<<16) | bootstrap_specifier_index;
 296   }
 297 
 298   void unresolved_string_at_put(int which, Symbol* s) {
 299     release_tag_at_put(which, JVM_CONSTANT_String);
 300     *symbol_at_addr(which) = s;
 301   }
 302 
 303   void int_at_put(int which, jint i) {
 304     tag_at_put(which, JVM_CONSTANT_Integer);
 305     *int_at_addr(which) = i;
 306   }
 307 
 308   void long_at_put(int which, jlong l) {
 309     tag_at_put(which, JVM_CONSTANT_Long);
 310     // *long_at_addr(which) = l;
 311     Bytes::put_native_u8((address)long_at_addr(which), *((u8*) &l));
 312   }
 313 
 314   void float_at_put(int which, jfloat f) {
 315     tag_at_put(which, JVM_CONSTANT_Float);
 316     *float_at_addr(which) = f;
 317   }
 318 
 319   void double_at_put(int which, jdouble d) {
 320     tag_at_put(which, JVM_CONSTANT_Double);
 321     // *double_at_addr(which) = d;
 322     // u8 temp = *(u8*) &d;
 323     Bytes::put_native_u8((address) double_at_addr(which), *((u8*) &d));
 324   }
 325 
 326   Symbol** symbol_at_addr(int which) const {
 327     assert(is_within_bounds(which), "index out of bounds");
 328     return (Symbol**) &base()[which];
 329   }
 330 
 331   void symbol_at_put(int which, Symbol* s) {
 332     assert(s->refcount() != 0, "should have nonzero refcount");
 333     tag_at_put(which, JVM_CONSTANT_Utf8);
 334     *symbol_at_addr(which) = s;
 335   }
 336 
 337   void string_at_put(int which, int obj_index, oop str) {
 338     resolved_references()->obj_at_put(obj_index, str);
 339   }
 340 
 341   // For temporary use while constructing constant pool
 342   void string_index_at_put(int which, int string_index) {
 343     tag_at_put(which, JVM_CONSTANT_StringIndex);
 344     *int_at_addr(which) = string_index;
 345   }
 346 
 347   void field_at_put(int which, int class_index, int name_and_type_index) {
 348     tag_at_put(which, JVM_CONSTANT_Fieldref);
 349     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
 350   }
 351 
 352   void method_at_put(int which, int class_index, int name_and_type_index) {
 353     tag_at_put(which, JVM_CONSTANT_Methodref);
 354     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
 355   }
 356 
 357   void interface_method_at_put(int which, int class_index, int name_and_type_index) {
 358     tag_at_put(which, JVM_CONSTANT_InterfaceMethodref);
 359     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;  // Not so nice
 360   }
 361 
 362   void name_and_type_at_put(int which, int name_index, int signature_index) {
 363     tag_at_put(which, JVM_CONSTANT_NameAndType);
 364     *int_at_addr(which) = ((jint) signature_index<<16) | name_index;  // Not so nice
 365   }
 366 
 367   // Tag query
 368 
 369   constantTag tag_at(int which) const { return (constantTag)tags()->at_acquire(which); }
 370 
 371   // Fetching constants
 372 
 373   Klass* klass_at(int which, TRAPS) {
 374     constantPoolHandle h_this(THREAD, this);
 375     return klass_at_impl(h_this, which, true, CHECK_NULL);
 376   }
 377 
 378   // Version of klass_at that doesn't save the resolution error, called during deopt
 379   Klass* klass_at_ignore_error(int which, TRAPS) {
 380     constantPoolHandle h_this(THREAD, this);
 381     return klass_at_impl(h_this, which, false, CHECK_NULL);
 382   }
 383 
 384   Symbol* klass_name_at(int which);  // Returns the name, w/o resolving.
 385 
 386   Klass* resolved_klass_at(int which) const {  // Used by Compiler
 387     guarantee(tag_at(which).is_klass(), "Corrupted constant pool");
 388     // Must do an acquire here in case another thread resolved the klass
 389     // behind our back, lest we later load stale values thru the oop.
 390     return CPSlot((Klass*)OrderAccess::load_ptr_acquire(obj_at_addr_raw(which))).get_klass();
 391   }
 392 
 393   // RedefineClasses() API support:
 394   Symbol* klass_at_noresolve(int which) { return klass_name_at(which); }
 395 
 396   jint int_at(int which) {
 397     assert(tag_at(which).is_int(), "Corrupted constant pool");
 398     return *int_at_addr(which);
 399   }
 400 
 401   jlong long_at(int which) {
 402     assert(tag_at(which).is_long(), "Corrupted constant pool");
 403     // return *long_at_addr(which);
 404     u8 tmp = Bytes::get_native_u8((address)&base()[which]);
 405     return *((jlong*)&tmp);
 406   }
 407 
 408   jfloat float_at(int which) {
 409     assert(tag_at(which).is_float(), "Corrupted constant pool");
 410     return *float_at_addr(which);
 411   }
 412 
 413   jdouble double_at(int which) {
 414     assert(tag_at(which).is_double(), "Corrupted constant pool");
 415     u8 tmp = Bytes::get_native_u8((address)&base()[which]);
 416     return *((jdouble*)&tmp);
 417   }
 418 
 419   Symbol* symbol_at(int which) {
 420     assert(tag_at(which).is_utf8(), "Corrupted constant pool");
 421     return *symbol_at_addr(which);
 422   }
 423 
 424   oop string_at(int which, int obj_index, TRAPS) {
 425     constantPoolHandle h_this(THREAD, this);
 426     return string_at_impl(h_this, which, obj_index, THREAD);
 427   }
 428   oop string_at(int which, TRAPS) {
 429     int obj_index = cp_to_object_index(which);
 430     return string_at(which, obj_index, THREAD);
 431   }
 432 
 433   // Version that can be used before string oop array is created.
 434   oop uncached_string_at(int which, TRAPS);
 435 
 436   // A "pseudo-string" is an non-string oop that has found its way into
 437   // a String entry.
 438   // This can happen if the user patches a live
 439   // object into a CONSTANT_String entry of an anonymous class.
 440   // Method oops internally created for method handles may also
 441   // use pseudo-strings to link themselves to related metaobjects.
 442 
 443   bool is_pseudo_string_at(int which) {
 444     // A pseudo string is a string that doesn't have a symbol in the cpSlot
 445     return unresolved_string_at(which) == NULL;
 446   }
 447 
 448   oop pseudo_string_at(int which, int obj_index) {
 449     assert(tag_at(which).is_string(), "Corrupted constant pool");
 450     assert(unresolved_string_at(which) == NULL, "shouldn't have symbol");
 451     oop s = resolved_references()->obj_at(obj_index);
 452     return s;
 453   }
 454 
 455   oop pseudo_string_at(int which) {
 456     assert(tag_at(which).is_string(), "Corrupted constant pool");
 457     assert(unresolved_string_at(which) == NULL, "shouldn't have symbol");
 458     int obj_index = cp_to_object_index(which);
 459     oop s = resolved_references()->obj_at(obj_index);
 460     return s;
 461   }
 462 
 463   void pseudo_string_at_put(int which, int obj_index, oop x) {
 464     assert(tag_at(which).is_string(), "Corrupted constant pool");
 465     unresolved_string_at_put(which, NULL); // indicates patched string
 466     string_at_put(which, obj_index, x);    // this works just fine
 467   }
 468 
 469   // only called when we are sure a string entry is already resolved (via an
 470   // earlier string_at call.
 471   oop resolved_string_at(int which) {
 472     assert(tag_at(which).is_string(), "Corrupted constant pool");
 473     // Must do an acquire here in case another thread resolved the klass
 474     // behind our back, lest we later load stale values thru the oop.
 475     // we might want a volatile_obj_at in ObjArrayKlass.
 476     int obj_index = cp_to_object_index(which);
 477     return resolved_references()->obj_at(obj_index);
 478   }
 479 
 480   Symbol* unresolved_string_at(int which) {
 481     assert(tag_at(which).is_string(), "Corrupted constant pool");
 482     Symbol* s = *symbol_at_addr(which);
 483     return s;
 484   }
 485 
 486   // Returns an UTF8 for a CONSTANT_String entry at a given index.
 487   // UTF8 char* representation was chosen to avoid conversion of
 488   // java_lang_Strings at resolved entries into Symbol*s
 489   // or vice versa.
 490   // Caller is responsible for checking for pseudo-strings.
 491   char* string_at_noresolve(int which);
 492 
 493   jint name_and_type_at(int which) {
 494     assert(tag_at(which).is_name_and_type(), "Corrupted constant pool");
 495     return *int_at_addr(which);
 496   }
 497 
 498  private:
 499   int method_handle_ref_kind_at(int which, bool error_ok) {
 500     assert(tag_at(which).is_method_handle() ||
 501            (error_ok && tag_at(which).is_method_handle_in_error()), "Corrupted constant pool");
 502     return extract_low_short_from_int(*int_at_addr(which));  // mask out unwanted ref_index bits
 503   }
 504   int method_handle_index_at(int which, bool error_ok) {
 505     assert(tag_at(which).is_method_handle() ||
 506            (error_ok && tag_at(which).is_method_handle_in_error()), "Corrupted constant pool");
 507     return extract_high_short_from_int(*int_at_addr(which));  // shift out unwanted ref_kind bits
 508   }
 509   int method_type_index_at(int which, bool error_ok) {
 510     assert(tag_at(which).is_method_type() ||
 511            (error_ok && tag_at(which).is_method_type_in_error()), "Corrupted constant pool");
 512     return *int_at_addr(which);
 513   }
 514  public:
 515   int method_handle_ref_kind_at(int which) {
 516     return method_handle_ref_kind_at(which, false);
 517   }
 518   int method_handle_ref_kind_at_error_ok(int which) {
 519     return method_handle_ref_kind_at(which, true);
 520   }
 521   int method_handle_index_at(int which) {
 522     return method_handle_index_at(which, false);
 523   }
 524   int method_handle_index_at_error_ok(int which) {
 525     return method_handle_index_at(which, true);
 526   }
 527   int method_type_index_at(int which) {
 528     return method_type_index_at(which, false);
 529   }
 530   int method_type_index_at_error_ok(int which) {
 531     return method_type_index_at(which, true);
 532   }
 533 
 534   // Derived queries:
 535   Symbol* method_handle_name_ref_at(int which) {
 536     int member = method_handle_index_at(which);
 537     return impl_name_ref_at(member, true);
 538   }
 539   Symbol* method_handle_signature_ref_at(int which) {
 540     int member = method_handle_index_at(which);
 541     return impl_signature_ref_at(member, true);
 542   }
 543   int method_handle_klass_index_at(int which) {
 544     int member = method_handle_index_at(which);
 545     return impl_klass_ref_index_at(member, true);
 546   }
 547   Symbol* method_type_signature_at(int which) {
 548     int sym = method_type_index_at(which);
 549     return symbol_at(sym);
 550   }
 551 
 552   int invoke_dynamic_name_and_type_ref_index_at(int which) {
 553     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 554     return extract_high_short_from_int(*int_at_addr(which));
 555   }
 556   int invoke_dynamic_bootstrap_specifier_index(int which) {
 557     assert(tag_at(which).value() == JVM_CONSTANT_InvokeDynamic, "Corrupted constant pool");
 558     return extract_low_short_from_int(*int_at_addr(which));
 559   }
 560   int invoke_dynamic_operand_base(int which) {
 561     int bootstrap_specifier_index = invoke_dynamic_bootstrap_specifier_index(which);
 562     return operand_offset_at(operands(), bootstrap_specifier_index);
 563   }
 564   // The first part of the operands array consists of an index into the second part.
 565   // Extract a 32-bit index value from the first part.
 566   static int operand_offset_at(Array<u2>* operands, int bootstrap_specifier_index) {
 567     int n = (bootstrap_specifier_index * 2);
 568     assert(n >= 0 && n+2 <= operands->length(), "oob");
 569     // The first 32-bit index points to the beginning of the second part
 570     // of the operands array.  Make sure this index is in the first part.
 571     DEBUG_ONLY(int second_part = build_int_from_shorts(operands->at(0),
 572                                                        operands->at(1)));
 573     assert(second_part == 0 || n+2 <= second_part, "oob (2)");
 574     int offset = build_int_from_shorts(operands->at(n+0),
 575                                        operands->at(n+1));
 576     // The offset itself must point into the second part of the array.
 577     assert(offset == 0 || offset >= second_part && offset <= operands->length(), "oob (3)");
 578     return offset;
 579   }
 580   static void operand_offset_at_put(Array<u2>* operands, int bootstrap_specifier_index, int offset) {
 581     int n = bootstrap_specifier_index * 2;
 582     assert(n >= 0 && n+2 <= operands->length(), "oob");
 583     operands->at_put(n+0, extract_low_short_from_int(offset));
 584     operands->at_put(n+1, extract_high_short_from_int(offset));
 585   }
 586   static int operand_array_length(Array<u2>* operands) {
 587     if (operands == NULL || operands->length() == 0)  return 0;
 588     int second_part = operand_offset_at(operands, 0);
 589     return (second_part / 2);
 590   }
 591 
 592 #ifdef ASSERT
 593   // operand tuples fit together exactly, end to end
 594   static int operand_limit_at(Array<u2>* operands, int bootstrap_specifier_index) {
 595     int nextidx = bootstrap_specifier_index + 1;
 596     if (nextidx == operand_array_length(operands))
 597       return operands->length();
 598     else
 599       return operand_offset_at(operands, nextidx);
 600   }
 601   int invoke_dynamic_operand_limit(int which) {
 602     int bootstrap_specifier_index = invoke_dynamic_bootstrap_specifier_index(which);
 603     return operand_limit_at(operands(), bootstrap_specifier_index);
 604   }
 605 #endif //ASSERT
 606 
 607   // layout of InvokeDynamic bootstrap method specifier (in second part of operands array):
 608   enum {
 609          _indy_bsm_offset  = 0,  // CONSTANT_MethodHandle bsm
 610          _indy_argc_offset = 1,  // u2 argc
 611          _indy_argv_offset = 2   // u2 argv[argc]
 612   };
 613 
 614   // These functions are used in RedefineClasses for CP merge
 615 
 616   int operand_offset_at(int bootstrap_specifier_index) {
 617     assert(0 <= bootstrap_specifier_index &&
 618            bootstrap_specifier_index < operand_array_length(operands()),
 619            "Corrupted CP operands");
 620     return operand_offset_at(operands(), bootstrap_specifier_index);
 621   }
 622   int operand_bootstrap_method_ref_index_at(int bootstrap_specifier_index) {
 623     int offset = operand_offset_at(bootstrap_specifier_index);
 624     return operands()->at(offset + _indy_bsm_offset);
 625   }
 626   int operand_argument_count_at(int bootstrap_specifier_index) {
 627     int offset = operand_offset_at(bootstrap_specifier_index);
 628     int argc = operands()->at(offset + _indy_argc_offset);
 629     return argc;
 630   }
 631   int operand_argument_index_at(int bootstrap_specifier_index, int j) {
 632     int offset = operand_offset_at(bootstrap_specifier_index);
 633     return operands()->at(offset + _indy_argv_offset + j);
 634   }
 635   int operand_next_offset_at(int bootstrap_specifier_index) {
 636     int offset = operand_offset_at(bootstrap_specifier_index) + _indy_argv_offset
 637                    + operand_argument_count_at(bootstrap_specifier_index);
 638     return offset;
 639   }
 640   // Compare a bootsrap specifier in the operands arrays
 641   bool compare_operand_to(int bootstrap_specifier_index1, constantPoolHandle cp2,
 642                           int bootstrap_specifier_index2, TRAPS);
 643   // Find a bootsrap specifier in the operands array
 644   int find_matching_operand(int bootstrap_specifier_index, constantPoolHandle search_cp,
 645                             int operands_cur_len, TRAPS);
 646   // Resize the operands array with delta_len and delta_size
 647   void resize_operands(int delta_len, int delta_size, TRAPS);
 648   // Extend the operands array with the length and size of the ext_cp operands
 649   void extend_operands(constantPoolHandle ext_cp, TRAPS);
 650   // Shrink the operands array to a smaller array with new_len length
 651   void shrink_operands(int new_len, TRAPS);
 652 
 653 
 654   int invoke_dynamic_bootstrap_method_ref_index_at(int which) {
 655     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 656     int op_base = invoke_dynamic_operand_base(which);
 657     return operands()->at(op_base + _indy_bsm_offset);
 658   }
 659   int invoke_dynamic_argument_count_at(int which) {
 660     assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
 661     int op_base = invoke_dynamic_operand_base(which);
 662     int argc = operands()->at(op_base + _indy_argc_offset);
 663     DEBUG_ONLY(int end_offset = op_base + _indy_argv_offset + argc;
 664                int next_offset = invoke_dynamic_operand_limit(which));
 665     assert(end_offset == next_offset, "matched ending");
 666     return argc;
 667   }
 668   int invoke_dynamic_argument_index_at(int which, int j) {
 669     int op_base = invoke_dynamic_operand_base(which);
 670     DEBUG_ONLY(int argc = operands()->at(op_base + _indy_argc_offset));
 671     assert((uint)j < (uint)argc, "oob");
 672     return operands()->at(op_base + _indy_argv_offset + j);
 673   }
 674 
 675   // The following methods (name/signature/klass_ref_at, klass_ref_at_noresolve,
 676   // name_and_type_ref_index_at) all expect to be passed indices obtained
 677   // directly from the bytecode.
 678   // If the indices are meant to refer to fields or methods, they are
 679   // actually rewritten constant pool cache indices.
 680   // The routine remap_instruction_operand_from_cache manages the adjustment
 681   // of these values back to constant pool indices.
 682 
 683   // There are also "uncached" versions which do not adjust the operand index; see below.
 684 
 685   // FIXME: Consider renaming these with a prefix "cached_" to make the distinction clear.
 686   // In a few cases (the verifier) there are uses before a cpcache has been built,
 687   // which are handled by a dynamic check in remap_instruction_operand_from_cache.
 688   // FIXME: Remove the dynamic check, and adjust all callers to specify the correct mode.
 689 
 690   // Lookup for entries consisting of (klass_index, name_and_type index)
 691   Klass* klass_ref_at(int which, TRAPS);
 692   Symbol* klass_ref_at_noresolve(int which);
 693   Symbol* name_ref_at(int which)                { return impl_name_ref_at(which, false); }
 694   Symbol* signature_ref_at(int which)           { return impl_signature_ref_at(which, false); }
 695 
 696   int klass_ref_index_at(int which)               { return impl_klass_ref_index_at(which, false); }
 697   int name_and_type_ref_index_at(int which)       { return impl_name_and_type_ref_index_at(which, false); }
 698 
 699   // Lookup for entries consisting of (name_index, signature_index)
 700   int name_ref_index_at(int which_nt);            // ==  low-order jshort of name_and_type_at(which_nt)
 701   int signature_ref_index_at(int which_nt);       // == high-order jshort of name_and_type_at(which_nt)
 702 
 703   BasicType basic_type_for_signature_at(int which);
 704 
 705   // Resolve string constants (to prevent allocation during compilation)
 706   void resolve_string_constants(TRAPS) {
 707     constantPoolHandle h_this(THREAD, this);
 708     resolve_string_constants_impl(h_this, CHECK);
 709   }
 710 
 711   // CDS support
 712   void remove_unshareable_info();
 713   void restore_unshareable_info(TRAPS);
 714   bool resolve_class_constants(TRAPS);
 715   // The ConstantPool vtable is restored by this call when the ConstantPool is
 716   // in the shared archive.  See patch_klass_vtables() in metaspaceShared.cpp for
 717   // all the gory details.  SA, dtrace and pstack helpers distinguish metadata
 718   // by their vtable.
 719   void restore_vtable() { guarantee(is_constantPool(), "vtable restored by this call"); }
 720 
 721  private:
 722   enum { _no_index_sentinel = -1, _possible_index_sentinel = -2 };
 723  public:
 724 
 725   // Resolve late bound constants.
 726   oop resolve_constant_at(int index, TRAPS) {
 727     constantPoolHandle h_this(THREAD, this);
 728     return resolve_constant_at_impl(h_this, index, _no_index_sentinel, THREAD);
 729   }
 730 
 731   oop resolve_cached_constant_at(int cache_index, TRAPS) {
 732     constantPoolHandle h_this(THREAD, this);
 733     return resolve_constant_at_impl(h_this, _no_index_sentinel, cache_index, THREAD);
 734   }
 735 
 736   oop resolve_possibly_cached_constant_at(int pool_index, TRAPS) {
 737     constantPoolHandle h_this(THREAD, this);
 738     return resolve_constant_at_impl(h_this, pool_index, _possible_index_sentinel, THREAD);
 739   }
 740 
 741   oop resolve_bootstrap_specifier_at(int index, TRAPS) {
 742     constantPoolHandle h_this(THREAD, this);
 743     return resolve_bootstrap_specifier_at_impl(h_this, index, THREAD);
 744   }
 745 
 746   // Klass name matches name at offset
 747   bool klass_name_at_matches(instanceKlassHandle k, int which);
 748 
 749   // Sizing
 750   int length() const                   { return _length; }
 751   void set_length(int length)          { _length = length; }
 752 
 753   // Tells whether index is within bounds.
 754   bool is_within_bounds(int index) const {
 755     return 0 <= index && index < length();
 756   }
 757 
 758   // Sizing (in words)
 759   static int header_size()             { return sizeof(ConstantPool)/HeapWordSize; }
 760   static int size(int length)          { return align_object_size(header_size() + length); }
 761   int size() const                     { return size(length()); }
 762 #if INCLUDE_SERVICES
 763   void collect_statistics(KlassSizeStats *sz) const;
 764 #endif
 765 
 766   friend class ClassFileParser;
 767   friend class SystemDictionary;
 768 
 769   // Used by compiler to prevent classloading.
 770   static Method*          method_at_if_loaded      (constantPoolHandle this_cp, int which);
 771   static bool       has_appendix_at_if_loaded      (constantPoolHandle this_cp, int which);
 772   static oop            appendix_at_if_loaded      (constantPoolHandle this_cp, int which);
 773   static bool    has_method_type_at_if_loaded      (constantPoolHandle this_cp, int which);
 774   static oop         method_type_at_if_loaded      (constantPoolHandle this_cp, int which);
 775   static Klass*            klass_at_if_loaded      (constantPoolHandle this_cp, int which);
 776   static Klass*        klass_ref_at_if_loaded      (constantPoolHandle this_cp, int which);
 777 
 778   // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the
 779   // future by other Java code. These take constant pool indices rather than
 780   // constant pool cache indices as do the peer methods above.
 781   Symbol* uncached_klass_ref_at_noresolve(int which);
 782   Symbol* uncached_name_ref_at(int which)                 { return impl_name_ref_at(which, true); }
 783   Symbol* uncached_signature_ref_at(int which)            { return impl_signature_ref_at(which, true); }
 784   int       uncached_klass_ref_index_at(int which)          { return impl_klass_ref_index_at(which, true); }
 785   int       uncached_name_and_type_ref_index_at(int which)  { return impl_name_and_type_ref_index_at(which, true); }
 786 
 787   // Sharing
 788   int pre_resolve_shared_klasses(TRAPS);
 789 
 790   // Debugging
 791   const char* printable_name_at(int which) PRODUCT_RETURN0;
 792 
 793 #ifdef ASSERT
 794   enum { CPCACHE_INDEX_TAG = 0x10000 };  // helps keep CP cache indices distinct from CP indices
 795 #else
 796   enum { CPCACHE_INDEX_TAG = 0 };        // in product mode, this zero value is a no-op
 797 #endif //ASSERT
 798 
 799   static int decode_cpcache_index(int raw_index, bool invokedynamic_ok = false) {
 800     if (invokedynamic_ok && is_invokedynamic_index(raw_index))
 801       return decode_invokedynamic_index(raw_index);
 802     else
 803       return raw_index - CPCACHE_INDEX_TAG;
 804   }
 805 
 806  private:
 807 
 808   void set_resolved_references(jobject s) { _resolved_references = s; }
 809   Array<u2>* reference_map() const        { return _reference_map; }
 810   void set_reference_map(Array<u2>* o)    { _reference_map = o; }
 811 
 812   // patch JSR 292 resolved references after the class is linked.
 813   void patch_resolved_references(GrowableArray<Handle>* cp_patches);
 814 
 815   Symbol* impl_name_ref_at(int which, bool uncached);
 816   Symbol* impl_signature_ref_at(int which, bool uncached);
 817   int       impl_klass_ref_index_at(int which, bool uncached);
 818   int       impl_name_and_type_ref_index_at(int which, bool uncached);
 819 
 820   int remap_instruction_operand_from_cache(int operand);  // operand must be biased by CPCACHE_INDEX_TAG
 821 
 822   // Used while constructing constant pool (only by ClassFileParser)
 823   jint klass_index_at(int which) {
 824     assert(tag_at(which).is_klass_index(), "Corrupted constant pool");
 825     return *int_at_addr(which);
 826   }
 827 
 828   jint string_index_at(int which) {
 829     assert(tag_at(which).is_string_index(), "Corrupted constant pool");
 830     return *int_at_addr(which);
 831   }
 832 
 833   // Performs the LinkResolver checks
 834   static void verify_constant_pool_resolve(constantPoolHandle this_cp, KlassHandle klass, TRAPS);
 835 
 836   // Implementation of methods that needs an exposed 'this' pointer, in order to
 837   // handle GC while executing the method
 838   static Klass* klass_at_impl(constantPoolHandle this_cp, int which,
 839                               bool save_resolution_error, TRAPS);
 840   static oop string_at_impl(constantPoolHandle this_cp, int which, int obj_index, TRAPS);
 841 
 842   static void trace_class_resolution(constantPoolHandle this_cp, KlassHandle k);
 843 
 844   // Resolve string constants (to prevent allocation during compilation)
 845   static void resolve_string_constants_impl(constantPoolHandle this_cp, TRAPS);
 846 
 847   static oop resolve_constant_at_impl(constantPoolHandle this_cp, int index, int cache_index, TRAPS);
 848   static oop resolve_bootstrap_specifier_at_impl(constantPoolHandle this_cp, int index, TRAPS);
 849 
 850   // Exception handling
 851   static void throw_resolution_error(constantPoolHandle this_cp, int which, TRAPS);
 852   static Symbol* exception_message(constantPoolHandle this_cp, int which, constantTag tag, oop pending_exception);
 853   static void save_and_throw_exception(constantPoolHandle this_cp, int which, constantTag tag, TRAPS);
 854 
 855  public:
 856   // Merging ConstantPool* support:
 857   bool compare_entry_to(int index1, constantPoolHandle cp2, int index2, TRAPS);
 858   void copy_cp_to(int start_i, int end_i, constantPoolHandle to_cp, int to_i, TRAPS) {
 859     constantPoolHandle h_this(THREAD, this);
 860     copy_cp_to_impl(h_this, start_i, end_i, to_cp, to_i, THREAD);
 861   }
 862   static void copy_cp_to_impl(constantPoolHandle from_cp, int start_i, int end_i, constantPoolHandle to_cp, int to_i, TRAPS);
 863   static void copy_entry_to(constantPoolHandle from_cp, int from_i, constantPoolHandle to_cp, int to_i, TRAPS);
 864   static void copy_operands(constantPoolHandle from_cp, constantPoolHandle to_cp, TRAPS);
 865   int  find_matching_entry(int pattern_i, constantPoolHandle search_cp, TRAPS);
 866   int  version() const                    { return _saved._version; }
 867   void set_version(int version)           { _saved._version = version; }
 868   void increment_and_save_version(int version) {
 869     _saved._version = version >= 0 ? (version + 1) : version;  // keep overflow
 870   }
 871 
 872   void set_resolved_reference_length(int length) { _saved._resolved_reference_length = length; }
 873   int  resolved_reference_length() const  { return _saved._resolved_reference_length; }
 874 
 875   // Decrease ref counts of symbols that are in the constant pool
 876   // when the holder class is unloaded
 877   void unreference_symbols();
 878 
 879   // Deallocate constant pool for RedefineClasses
 880   void deallocate_contents(ClassLoaderData* loader_data);
 881   void release_C_heap_structures();
 882 
 883   // JVMTI accesss - GetConstantPool, RetransformClasses, ...
 884   friend class JvmtiConstantPoolReconstituter;
 885 
 886  private:
 887   jint cpool_entry_size(jint idx);
 888   jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap);
 889 
 890   // Copy cpool bytes into byte array.
 891   // Returns:
 892   //  int > 0, count of the raw cpool bytes that have been copied
 893   //        0, OutOfMemory error
 894   //       -1, Internal error
 895   int  copy_cpool_bytes(int cpool_size,
 896                         SymbolHashMap* tbl,
 897                         unsigned char *bytes);
 898 
 899  public:
 900   // Verify
 901   void verify_on(outputStream* st);
 902 
 903   // Printing
 904   void print_on(outputStream* st) const;
 905   void print_value_on(outputStream* st) const;
 906   void print_entry_on(int index, outputStream* st);
 907 
 908   const char* internal_name() const { return "{constant pool}"; }
 909 
 910 #ifndef PRODUCT
 911   // Compile the world support
 912   static void preload_and_initialize_all_classes(ConstantPool* constant_pool, TRAPS);
 913 #endif
 914 };
 915 
 916 class SymbolHashMapEntry : public CHeapObj<mtSymbol> {
 917  private:
 918   unsigned int        _hash;   // 32-bit hash for item
 919   SymbolHashMapEntry* _next;   // Next element in the linked list for this bucket
 920   Symbol*             _symbol; // 1-st part of the mapping: symbol => value
 921   u2                  _value;  // 2-nd part of the mapping: symbol => value
 922 
 923  public:
 924   unsigned   int hash() const             { return _hash;   }
 925   void       set_hash(unsigned int hash)  { _hash = hash;   }
 926 
 927   SymbolHashMapEntry* next() const        { return _next;   }
 928   void set_next(SymbolHashMapEntry* next) { _next = next;   }
 929 
 930   Symbol*    symbol() const               { return _symbol; }
 931   void       set_symbol(Symbol* sym)      { _symbol = sym;  }
 932 
 933   u2         value() const                {  return _value; }
 934   void       set_value(u2 value)          { _value = value; }
 935 
 936   SymbolHashMapEntry(unsigned int hash, Symbol* symbol, u2 value)
 937     : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {}
 938 
 939 }; // End SymbolHashMapEntry class
 940 
 941 
 942 class SymbolHashMapBucket : public CHeapObj<mtSymbol> {
 943 
 944 private:
 945   SymbolHashMapEntry*    _entry;
 946 
 947 public:
 948   SymbolHashMapEntry* entry() const         {  return _entry; }
 949   void set_entry(SymbolHashMapEntry* entry) { _entry = entry; }
 950   void clear()                              { _entry = NULL;  }
 951 
 952 }; // End SymbolHashMapBucket class
 953 
 954 
 955 class SymbolHashMap: public CHeapObj<mtSymbol> {
 956 
 957  private:
 958   // Default number of entries in the table
 959   enum SymbolHashMap_Constants {
 960     _Def_HashMap_Size = 256
 961   };
 962 
 963   int                   _table_size;
 964   SymbolHashMapBucket*  _buckets;
 965 
 966   void initialize_table(int table_size) {
 967     _table_size = table_size;
 968     _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size, mtSymbol);
 969     for (int index = 0; index < table_size; index++) {
 970       _buckets[index].clear();
 971     }
 972   }
 973 
 974  public:
 975 
 976   int table_size() const        { return _table_size; }
 977 
 978   SymbolHashMap()               { initialize_table(_Def_HashMap_Size); }
 979   SymbolHashMap(int table_size) { initialize_table(table_size); }
 980 
 981   // hash P(31) from Kernighan & Ritchie
 982   static unsigned int compute_hash(const char* str, int len) {
 983     unsigned int hash = 0;
 984     while (len-- > 0) {
 985       hash = 31*hash + (unsigned) *str;
 986       str++;
 987     }
 988     return hash;
 989   }
 990 
 991   SymbolHashMapEntry* bucket(int i) {
 992     return _buckets[i].entry();
 993   }
 994 
 995   void add_entry(Symbol* sym, u2 value);
 996   SymbolHashMapEntry* find_entry(Symbol* sym);
 997 
 998   u2 symbol_to_value(Symbol* sym) {
 999     SymbolHashMapEntry *entry = find_entry(sym);
1000     return (entry == NULL) ? 0 : entry->value();
1001   }
1002 
1003   ~SymbolHashMap() {
1004     SymbolHashMapEntry* next;
1005     for (int i = 0; i < _table_size; i++) {
1006       for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) {
1007         next = cur->next();
1008         delete(cur);
1009       }
1010     }
1011     delete _buckets;
1012   }
1013 }; // End SymbolHashMap class
1014 
1015 #endif // SHARE_VM_OOPS_CONSTANTPOOLOOP_HPP