1 /*

     2  * Copyright 1997-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 // A constantPool is an array containing class constants as described in the

    26 // class file.

    27 //

    28 // Most of the constant pool entries are written during class parsing, which

    29 // is safe.  For klass and string types, the constant pool entry is

    30 // modified when the entry is resolved.  If a klass or string constant pool

    31 // entry is read without a lock, only the resolved state guarantees that

    32 // the entry in the constant pool is a klass or String object and

    33 // not a symbolOop.

    34 

    35 class SymbolHashMap;

    36 

    37 class constantPoolOopDesc : public arrayOopDesc {

    38   friend class VMStructs;

    39   friend class BytecodeInterpreter;  // Directly extracts an oop in the pool for fast instanceof/checkcast

    40  private:

    41   typeArrayOop         _tags; // the tag array describing the constant pool's contents

    42   constantPoolCacheOop _cache;         // the cache holding interpreter runtime information

    43   klassOop             _pool_holder;   // the corresponding class

    44   // only set to non-zero if constant pool is merged by RedefineClasses

    45   int                  _orig_length;

    46 

    47   void set_tags(typeArrayOop tags)             { oop_store_without_check((oop*)&_tags, tags); }

    48   void tag_at_put(int which, jbyte t)          { tags()->byte_at_put(which, t); }

    49   void release_tag_at_put(int which, jbyte t)  { tags()->release_byte_at_put(which, t); }

    50 

    51  private:

    52   intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(constantPoolOopDesc)); }

    53   oop* tags_addr()       { return (oop*)&_tags; }

    54   oop* cache_addr()      { return (oop*)&_cache; }

    55 

    56   oop* obj_at_addr(int which) const {

    57     assert(is_within_bounds(which), "index out of bounds");

    58     return (oop*) &base()[which];

    59   }

    60 

    61   jint* int_at_addr(int which) const {

    62     assert(is_within_bounds(which), "index out of bounds");

    63     return (jint*) &base()[which];

    64   }

    65 

    66   jlong* long_at_addr(int which) const {

    67     assert(is_within_bounds(which), "index out of bounds");

    68     return (jlong*) &base()[which];

    69   }

    70 

    71   jfloat* float_at_addr(int which) const {

    72     assert(is_within_bounds(which), "index out of bounds");

    73     return (jfloat*) &base()[which];

    74   }

    75 

    76   jdouble* double_at_addr(int which) const {

    77     assert(is_within_bounds(which), "index out of bounds");

    78     return (jdouble*) &base()[which];

    79   }

    80 

    81  public:

    82   typeArrayOop tags() const                 { return _tags; }

    83 

    84   // Klass holding pool

    85   klassOop pool_holder() const              { return _pool_holder; }

    86   void set_pool_holder(klassOop k)          { oop_store_without_check((oop*)&_pool_holder, (oop) k); }

    87   oop* pool_holder_addr()                   { return (oop*)&_pool_holder; }

    88 

    89   // Interpreter runtime support

    90   constantPoolCacheOop cache() const        { return _cache; }

    91   void set_cache(constantPoolCacheOop cache){ oop_store((oop*)&_cache, cache); }

    92 

    93   // Assembly code support

    94   static int tags_offset_in_bytes()         { return offset_of(constantPoolOopDesc, _tags); }

    95   static int cache_offset_in_bytes()        { return offset_of(constantPoolOopDesc, _cache); }

    96   static int pool_holder_offset_in_bytes()  { return offset_of(constantPoolOopDesc, _pool_holder); }

    97 

    98   // Storing constants

    99 

   100   void klass_at_put(int which, klassOop k) {

   101     oop_store_without_check((volatile oop *)obj_at_addr(which), oop(k));

   102     // The interpreter assumes when the tag is stored, the klass is resolved

   103     // and the klassOop is a klass rather than a symbolOop, so we need

   104     // hardware store ordering here.

   105     release_tag_at_put(which, JVM_CONSTANT_Class);

   106     if (UseConcMarkSweepGC) {

   107       // In case the earlier card-mark was consumed by a concurrent

   108       // marking thread before the tag was updated, redirty the card.

   109       oop_store_without_check((volatile oop *)obj_at_addr(which), oop(k));

   110     }

   111   }

   112 

   113   // For temporary use while constructing constant pool

   114   void klass_index_at_put(int which, int name_index) {

   115     tag_at_put(which, JVM_CONSTANT_ClassIndex);

   116     *int_at_addr(which) = name_index;

   117   }

   118 

   119   // Temporary until actual use

   120   void unresolved_klass_at_put(int which, symbolOop s) {

   121     // Overwrite the old index with a GC friendly value so

   122     // that if GC looks during the transition it won't try

   123     // to treat a small integer as oop.

   124     *obj_at_addr(which) = NULL;

   125     release_tag_at_put(which, JVM_CONSTANT_UnresolvedClass);

   126     oop_store_without_check(obj_at_addr(which), oop(s));

   127   }

   128 

   129   // Temporary until actual use

   130   void unresolved_string_at_put(int which, symbolOop s) {

   131     *obj_at_addr(which) = NULL;

   132     release_tag_at_put(which, JVM_CONSTANT_UnresolvedString);

   133     oop_store_without_check(obj_at_addr(which), oop(s));

   134   }

   135 

   136   void int_at_put(int which, jint i) {

   137     tag_at_put(which, JVM_CONSTANT_Integer);

   138     *int_at_addr(which) = i;

   139   }

   140 

   141   void long_at_put(int which, jlong l) {

   142     tag_at_put(which, JVM_CONSTANT_Long);

   143     // *long_at_addr(which) = l;

   144     Bytes::put_native_u8((address)long_at_addr(which), *((u8*) &l));

   145   }

   146 

   147   void float_at_put(int which, jfloat f) {

   148     tag_at_put(which, JVM_CONSTANT_Float);

   149     *float_at_addr(which) = f;

   150   }

   151 

   152   void double_at_put(int which, jdouble d) {

   153     tag_at_put(which, JVM_CONSTANT_Double);

   154     // *double_at_addr(which) = d;

   155     // u8 temp = *(u8*) &d;

   156     Bytes::put_native_u8((address) double_at_addr(which), *((u8*) &d));

   157   }

   158 

   159   void symbol_at_put(int which, symbolOop s) {

   160     tag_at_put(which, JVM_CONSTANT_Utf8);

   161     oop_store_without_check(obj_at_addr(which), oop(s));

   162   }

   163 

   164   void string_at_put(int which, oop str) {

   165     oop_store((volatile oop*)obj_at_addr(which), str);

   166     release_tag_at_put(which, JVM_CONSTANT_String);

   167     if (UseConcMarkSweepGC) {

   168       // In case the earlier card-mark was consumed by a concurrent

   169       // marking thread before the tag was updated, redirty the card.

   170       oop_store_without_check((volatile oop *)obj_at_addr(which), str);

   171     }

   172   }

   173 

   174   // For temporary use while constructing constant pool

   175   void string_index_at_put(int which, int string_index) {

   176     tag_at_put(which, JVM_CONSTANT_StringIndex);

   177     *int_at_addr(which) = string_index;

   178   }

   179 

   180   void field_at_put(int which, int class_index, int name_and_type_index) {

   181     tag_at_put(which, JVM_CONSTANT_Fieldref);

   182     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;

   183   }

   184 

   185   void method_at_put(int which, int class_index, int name_and_type_index) {

   186     tag_at_put(which, JVM_CONSTANT_Methodref);

   187     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;

   188   }

   189 

   190   void interface_method_at_put(int which, int class_index, int name_and_type_index) {

   191     tag_at_put(which, JVM_CONSTANT_InterfaceMethodref);

   192     *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;  // Not so nice

   193   }

   194 

   195   void name_and_type_at_put(int which, int name_index, int signature_index) {

   196     tag_at_put(which, JVM_CONSTANT_NameAndType);

   197     *int_at_addr(which) = ((jint) signature_index<<16) | name_index;  // Not so nice

   198   }

   199 

   200   // Tag query

   201 

   202   constantTag tag_at(int which) const { return (constantTag)tags()->byte_at_acquire(which); }

   203 

   204   // Whether the entry is a pointer that must be GC'd.

   205   bool is_pointer_entry(int which) {

   206     constantTag tag = tag_at(which);

   207     return tag.is_klass() ||

   208       tag.is_unresolved_klass() ||

   209       tag.is_symbol() ||

   210       tag.is_unresolved_string() ||

   211       tag.is_string();

   212   }

   213 

   214   // Fetching constants

   215 

   216   klassOop klass_at(int which, TRAPS) {

   217     constantPoolHandle h_this(THREAD, this);

   218     return klass_at_impl(h_this, which, CHECK_NULL);

   219   }

   220 

   221   symbolOop klass_name_at(int which);  // Returns the name, w/o resolving.

   222 

   223   klassOop resolved_klass_at(int which) {  // Used by Compiler

   224     guarantee(tag_at(which).is_klass(), "Corrupted constant pool");

   225     // Must do an acquire here in case another thread resolved the klass

   226     // behind our back, lest we later load stale values thru the oop.

   227     return klassOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));

   228   }

   229 

   230   // This method should only be used with a cpool lock or during parsing or gc

   231   symbolOop unresolved_klass_at(int which) {     // Temporary until actual use

   232     symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));

   233     // check that the klass is still unresolved.

   234     assert(tag_at(which).is_unresolved_klass(), "Corrupted constant pool");

   235     return s;

   236   }

   237 

   238   // RedefineClasses() API support:

   239   symbolOop klass_at_noresolve(int which) { return klass_name_at(which); }

   240 

   241   jint int_at(int which) {

   242     assert(tag_at(which).is_int(), "Corrupted constant pool");

   243     return *int_at_addr(which);

   244   }

   245 

   246   jlong long_at(int which) {

   247     assert(tag_at(which).is_long(), "Corrupted constant pool");

   248     // return *long_at_addr(which);

   249     u8 tmp = Bytes::get_native_u8((address)&base()[which]);

   250     return *((jlong*)&tmp);

   251   }

   252 

   253   jfloat float_at(int which) {

   254     assert(tag_at(which).is_float(), "Corrupted constant pool");

   255     return *float_at_addr(which);

   256   }

   257 

   258   jdouble double_at(int which) {

   259     assert(tag_at(which).is_double(), "Corrupted constant pool");

   260     u8 tmp = Bytes::get_native_u8((address)&base()[which]);

   261     return *((jdouble*)&tmp);

   262   }

   263 

   264   symbolOop symbol_at(int which) {

   265     assert(tag_at(which).is_utf8(), "Corrupted constant pool");

   266     return symbolOop(*obj_at_addr(which));

   267   }

   268 

   269   oop string_at(int which, TRAPS) {

   270     constantPoolHandle h_this(THREAD, this);

   271     return string_at_impl(h_this, which, CHECK_NULL);

   272   }

   273 

   274   // only called when we are sure a string entry is already resolved (via an

   275   // earlier string_at call.

   276   oop resolved_string_at(int which) {

   277     assert(tag_at(which).is_string(), "Corrupted constant pool");

   278     // Must do an acquire here in case another thread resolved the klass

   279     // behind our back, lest we later load stale values thru the oop.

   280     return (oop)OrderAccess::load_ptr_acquire(obj_at_addr(which));

   281   }

   282 

   283   // This method should only be used with a cpool lock or during parsing or gc

   284   symbolOop unresolved_string_at(int which) {    // Temporary until actual use

   285     symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));

   286     // check that the string is still unresolved.

   287     assert(tag_at(which).is_unresolved_string(), "Corrupted constant pool");

   288     return s;

   289   }

   290 

   291   // Returns an UTF8 for a CONSTANT_String entry at a given index.

   292   // UTF8 char* representation was chosen to avoid conversion of

   293   // java_lang_Strings at resolved entries into symbolOops

   294   // or vice versa.

   295   char* string_at_noresolve(int which);

   296 

   297   jint name_and_type_at(int which) {

   298     assert(tag_at(which).is_name_and_type(), "Corrupted constant pool");

   299     return *int_at_addr(which);

   300   }

   301 

   302   // The following methods (klass_ref_at, klass_ref_at_noresolve, name_ref_at,

   303   // signature_ref_at, klass_ref_index_at, name_and_type_ref_index_at,

   304   // name_ref_index_at, signature_ref_index_at) all expect constant pool indices

   305   // from the bytecodes to be passed in, which are actually potentially byte-swapped

   306   // contstant pool cache indices. See field_or_method_at.

   307 

   308   // Lookup for entries consisting of (klass_index, name_and_type index)

   309   klassOop klass_ref_at(int which, TRAPS);

   310   symbolOop klass_ref_at_noresolve(int which);

   311   symbolOop name_ref_at(int which);

   312   symbolOop signature_ref_at(int which);    // the type descriptor

   313 

   314   int klass_ref_index_at(int which);

   315   int name_and_type_ref_index_at(int which);

   316 

   317   // Lookup for entries consisting of (name_index, signature_index)

   318   int name_ref_index_at(int which);

   319   int signature_ref_index_at(int which);

   320 

   321   BasicType basic_type_for_signature_at(int which);

   322 

   323   // Resolve string constants (to prevent allocation during compilation)

   324   void resolve_string_constants(TRAPS) {

   325     constantPoolHandle h_this(THREAD, this);

   326     resolve_string_constants_impl(h_this, CHECK);

   327   }

   328 

   329   // Klass name matches name at offset

   330   bool klass_name_at_matches(instanceKlassHandle k, int which);

   331 

   332   // Sizing

   333   static int header_size()             { return sizeof(constantPoolOopDesc)/HeapWordSize; }

   334   static int object_size(int length)   { return align_object_size(header_size() + length); }

   335   int object_size()                    { return object_size(length()); }

   336 

   337   friend class constantPoolKlass;

   338   friend class ClassFileParser;

   339   friend class SystemDictionary;

   340 

   341   // Used by compiler to prevent classloading.

   342   static klassOop klass_at_if_loaded          (constantPoolHandle this_oop, int which);

   343   static klassOop klass_ref_at_if_loaded      (constantPoolHandle this_oop, int which);

   344   // Same as above - but does LinkResolving.

   345   static klassOop klass_ref_at_if_loaded_check(constantPoolHandle this_oop, int which, TRAPS);

   346 

   347   // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the

   348   // future by other Java code. These take constant pool indices rather than possibly-byte-swapped

   349   // constant pool cache indices as do the peer methods above.

   350   symbolOop uncached_name_ref_at(int which);

   351   symbolOop uncached_signature_ref_at(int which);

   352   int       uncached_klass_ref_index_at(int which);

   353   int       uncached_name_and_type_ref_index_at(int which);

   354 

   355   // Sharing

   356   int pre_resolve_shared_klasses(TRAPS);

   357   void shared_symbols_iterate(OopClosure* closure0);

   358   void shared_tags_iterate(OopClosure* closure0);

   359   void shared_strings_iterate(OopClosure* closure0);

   360 

   361   // Debugging

   362   const char* printable_name_at(int which) PRODUCT_RETURN0;

   363 

   364  private:

   365 

   366   // Takes either a constant pool cache index in possibly byte-swapped

   367   // byte order (which comes from the bytecodes after rewriting) or,

   368   // if "uncached" is true, a vanilla constant pool index

   369   jint field_or_method_at(int which, bool uncached) {

   370     int i = -1;

   371     if (uncached || cache() == NULL) {

   372       i = which;

   373     } else {

   374       // change byte-ordering and go via cache

   375       i = cache()->entry_at(Bytes::swap_u2(which))->constant_pool_index();

   376     }

   377     assert(tag_at(i).is_field_or_method(), "Corrupted constant pool");

   378     return *int_at_addr(i);

   379   }

   380 

   381   // Used while constructing constant pool (only by ClassFileParser)

   382   jint klass_index_at(int which) {

   383     assert(tag_at(which).is_klass_index(), "Corrupted constant pool");

   384     return *int_at_addr(which);

   385   }

   386 

   387   jint string_index_at(int which) {

   388     assert(tag_at(which).is_string_index(), "Corrupted constant pool");

   389     return *int_at_addr(which);

   390   }

   391 

   392   // Performs the LinkResolver checks

   393   static void verify_constant_pool_resolve(constantPoolHandle this_oop, KlassHandle klass, TRAPS);

   394 

   395   // Implementation of methods that needs an exposed 'this' pointer, in order to

   396   // handle GC while executing the method

   397   static klassOop klass_at_impl(constantPoolHandle this_oop, int which, TRAPS);

   398   static oop string_at_impl(constantPoolHandle this_oop, int which, TRAPS);

   399 

   400   // Resolve string constants (to prevent allocation during compilation)

   401   static void resolve_string_constants_impl(constantPoolHandle this_oop, TRAPS);

   402 

   403  public:

   404   // Merging constantPoolOop support:

   405   bool compare_entry_to(int index1, constantPoolHandle cp2, int index2, TRAPS);

   406   void copy_cp_to(int start_i, int end_i, constantPoolHandle to_cp, int to_i,

   407     TRAPS);

   408   void copy_entry_to(int from_i, constantPoolHandle to_cp, int to_i, TRAPS);

   409   int  find_matching_entry(int pattern_i, constantPoolHandle search_cp, TRAPS);

   410   int  orig_length() const                { return _orig_length; }

   411   void set_orig_length(int orig_length)   { _orig_length = orig_length; }

   412 

   413 

   414   // JVMTI accesss - GetConstantPool, RetransformClasses, ...

   415   friend class JvmtiConstantPoolReconstituter;

   416 

   417  private:

   418   jint cpool_entry_size(jint idx);

   419   jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap);

   420 

   421   // Copy cpool bytes into byte array.

   422   // Returns:

   423   //  int > 0, count of the raw cpool bytes that have been copied

   424   //        0, OutOfMemory error

   425   //       -1, Internal error

   426   int  copy_cpool_bytes(int cpool_size,

   427                         SymbolHashMap* tbl,

   428                         unsigned char *bytes);

   429 };

   430 

   431 class SymbolHashMapEntry : public CHeapObj {

   432  private:

   433   unsigned int        _hash;   // 32-bit hash for item

   434   SymbolHashMapEntry* _next;   // Next element in the linked list for this bucket

   435   symbolOop           _symbol; // 1-st part of the mapping: symbol => value

   436   u2                  _value;  // 2-nd part of the mapping: symbol => value

   437 

   438  public:

   439   unsigned   int hash() const             { return _hash;   }

   440   void       set_hash(unsigned int hash)  { _hash = hash;   }

   441 

   442   SymbolHashMapEntry* next() const        { return _next;   }

   443   void set_next(SymbolHashMapEntry* next) { _next = next;   }

   444 

   445   symbolOop  symbol() const               { return _symbol; }

   446   void       set_symbol(symbolOop sym)    { _symbol = sym;  }

   447 

   448   u2         value() const                {  return _value; }

   449   void       set_value(u2 value)          { _value = value; }

   450 

   451   SymbolHashMapEntry(unsigned int hash, symbolOop symbol, u2 value)

   452     : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {}

   453 

   454 }; // End SymbolHashMapEntry class

   455 

   456 

   457 class SymbolHashMapBucket : public CHeapObj {

   458 

   459 private:

   460   SymbolHashMapEntry*    _entry;

   461 

   462 public:

   463   SymbolHashMapEntry* entry() const         {  return _entry; }

   464   void set_entry(SymbolHashMapEntry* entry) { _entry = entry; }

   465   void clear()                              { _entry = NULL;  }

   466 

   467 }; // End SymbolHashMapBucket class

   468 

   469 

   470 class SymbolHashMap: public CHeapObj {

   471 

   472  private:

   473   // Default number of entries in the table

   474   enum SymbolHashMap_Constants {

   475     _Def_HashMap_Size = 256

   476   };

   477 

   478   int                   _table_size;

   479   SymbolHashMapBucket*  _buckets;

   480 

   481   void initialize_table(int table_size) {

   482     _table_size = table_size;

   483     _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size);

   484     for (int index = 0; index < table_size; index++) {

   485       _buckets[index].clear();

   486     }

   487   }

   488 

   489  public:

   490 

   491   int table_size() const        { return _table_size; }

   492 

   493   SymbolHashMap()               { initialize_table(_Def_HashMap_Size); }

   494   SymbolHashMap(int table_size) { initialize_table(table_size); }

   495 

   496   // hash P(31) from Kernighan & Ritchie

   497   static unsigned int compute_hash(const char* str, int len) {

   498     unsigned int hash = 0;

   499     while (len-- > 0) {

   500       hash = 31*hash + (unsigned) *str;

   501       str++;

   502     }

   503     return hash;

   504   }

   505 

   506   SymbolHashMapEntry* bucket(int i) {

   507     return _buckets[i].entry();

   508   }

   509 

   510   void add_entry(symbolOop sym, u2 value);

   511   SymbolHashMapEntry* find_entry(symbolOop sym);

   512 

   513   u2 symbol_to_value(symbolOop sym) {

   514     SymbolHashMapEntry *entry = find_entry(sym);

   515     return (entry == NULL) ? 0 : entry->value();

   516   }

   517 

   518   ~SymbolHashMap() {

   519     SymbolHashMapEntry* next;

   520     for (int i = 0; i < _table_size; i++) {

   521       for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) {

   522         next = cur->next();

   523         delete(cur);

   524       }

   525     }

   526     delete _buckets;

   527   }

   528 }; // End SymbolHashMap class