1 /*
  2  * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
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  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
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 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
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 24 
 25 #ifndef SHARE_OOPS_CONSTANTPOOL_HPP
 26 #define SHARE_OOPS_CONSTANTPOOL_HPP
 27 
 28 #include "memory/allocation.hpp"
 29 #include "oops/arrayOop.hpp"
 30 #include "oops/cpCache.hpp"
 31 #include "oops/objArrayOop.hpp"
 32 #include "oops/oopHandle.hpp"
 33 #include "oops/symbol.hpp"
 34 #include "oops/typeArrayOop.hpp"
 35 #include "runtime/handles.hpp"
 36 #include "runtime/javaThread.hpp"
 37 #include "utilities/align.hpp"
 38 #include "utilities/bytes.hpp"
 39 #include "utilities/constantTag.hpp"
 40 #include "utilities/resourceHash.hpp"
 41 
 42 // A ConstantPool is an array containing class constants as described in the
 43 // class file.
 44 //
 45 // Most of the constant pool entries are written during class parsing, which
 46 // is safe.  For klass types, the constant pool entry is
 47 // modified when the entry is resolved.  If a klass constant pool
 48 // entry is read without a lock, only the resolved state guarantees that
 49 // the entry in the constant pool is a klass object and not a Symbol*.
 50 
 51 // This represents a JVM_CONSTANT_Class, JVM_CONSTANT_UnresolvedClass, or
 52 // JVM_CONSTANT_UnresolvedClassInError slot in the constant pool.
 53 class CPKlassSlot {
 54   // cp->symbol_at(_name_index) gives the name of the class.
 55   int _name_index;
 56 
 57   // cp->_resolved_klasses->at(_resolved_klass_index) gives the Klass* for the class.
 58   int _resolved_klass_index;
 59 public:
 60   enum {
 61     // This is used during constant pool merging where the resolved klass index is
 62     // not yet known, and will be computed at a later stage (during a call to
 63     // initialize_unresolved_klasses()).
 64     _temp_resolved_klass_index = 0xffff
 65   };
 66   CPKlassSlot(int n, int rk) {
 67     _name_index = n;
 68     _resolved_klass_index = rk;
 69   }
 70   int name_index() const {
 71     return _name_index;
 72   }
 73   int resolved_klass_index() const {
 74     assert(_resolved_klass_index != _temp_resolved_klass_index, "constant pool merging was incomplete");
 75     return _resolved_klass_index;
 76   }
 77 };
 78 
 79 class ConstantPool : public Metadata {
 80   friend class VMStructs;
 81   friend class JVMCIVMStructs;
 82   friend class BytecodeInterpreter;  // Directly extracts a klass in the pool for fast instanceof/checkcast
 83   friend class Universe;             // For null constructor
 84   friend class ClassPrelinker;       // CDS
 85  private:
 86   // If you add a new field that points to any metaspace object, you
 87   // must add this field to ConstantPool::metaspace_pointers_do().
 88   Array<u1>*           _tags;        // the tag array describing the constant pool's contents
 89   ConstantPoolCache*   _cache;       // the cache holding interpreter runtime information
 90   InstanceKlass*       _pool_holder; // the corresponding class
 91   Array<u2>*           _operands;    // for variable-sized (InvokeDynamic) nodes, usually empty
 92 
 93   // Consider using an array of compressed klass pointers to
 94   // save space on 64-bit platforms.
 95   Array<Klass*>*       _resolved_klasses;
 96 
 97   u2              _major_version;        // major version number of class file
 98   u2              _minor_version;        // minor version number of class file
 99 
100   // Constant pool index to the utf8 entry of the Generic signature,
101   // or 0 if none.
102   u2              _generic_signature_index;
103   // Constant pool index to the utf8 entry for the name of source file
104   // containing this klass, 0 if not specified.
105   u2              _source_file_name_index;
106 
107   enum {
108     _has_preresolution    = 1,       // Flags
109     _on_stack             = 2,
110     _is_shared            = 4,
111     _has_dynamic_constant = 8,
112     _is_for_method_handle_intrinsic = 16
113   };
114 
115   u2              _flags;  // old fashioned bit twiddling
116 
117   int             _length; // number of elements in the array
118 
119   union {
120     // set for CDS to restore resolved references
121     int                _resolved_reference_length;
122     // keeps version number for redefined classes (used in backtrace)
123     int                _version;
124   } _saved;
125 
126   void set_tags(Array<u1>* tags)                 { _tags = tags; }
127   void tag_at_put(int cp_index, jbyte t)         { tags()->at_put(cp_index, t); }
128   void release_tag_at_put(int cp_index, jbyte t) { tags()->release_at_put(cp_index, t); }
129 
130   u1* tag_addr_at(int cp_index) const            { return tags()->adr_at(cp_index); }
131 
132   void set_operands(Array<u2>* operands)       { _operands = operands; }
133 
134   u2 flags() const                             { return _flags; }
135   void set_flags(u2 f)                         { _flags = f; }
136 
137  private:
138   intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(ConstantPool)); }
139 
140   intptr_t* obj_at_addr(int cp_index) const {
141     assert(is_within_bounds(cp_index), "index out of bounds");
142     return (intptr_t*) &base()[cp_index];
143   }
144 
145   jint* int_at_addr(int cp_index) const {
146     assert(is_within_bounds(cp_index), "index out of bounds");
147     return (jint*) &base()[cp_index];
148   }
149 
150   jlong* long_at_addr(int cp_index) const {
151     assert(is_within_bounds(cp_index), "index out of bounds");
152     return (jlong*) &base()[cp_index];
153   }
154 
155   jfloat* float_at_addr(int cp_index) const {
156     assert(is_within_bounds(cp_index), "index out of bounds");
157     return (jfloat*) &base()[cp_index];
158   }
159 
160   jdouble* double_at_addr(int cp_index) const {
161     assert(is_within_bounds(cp_index), "index out of bounds");
162     return (jdouble*) &base()[cp_index];
163   }
164 
165   ConstantPool(Array<u1>* tags);
166   ConstantPool();
167  public:
168   static ConstantPool* allocate(ClassLoaderData* loader_data, int length, TRAPS);
169 
170   virtual bool is_constantPool() const      { return true; }
171 
172   Array<u1>* tags() const                   { return _tags; }
173   Array<u2>* operands() const               { return _operands; }
174 
175   bool has_preresolution() const            { return (_flags & _has_preresolution) != 0; }
176   void set_has_preresolution() {
177     assert(!is_shared(), "should never be called on shared ConstantPools");
178     _flags |= _has_preresolution;
179   }
180 
181   // minor and major version numbers of class file
182   u2 major_version() const                 { return _major_version; }
183   void set_major_version(u2 major_version) { _major_version = major_version; }
184   u2 minor_version() const                 { return _minor_version; }
185   void set_minor_version(u2 minor_version) { _minor_version = minor_version; }
186 
187   // generics support
188   Symbol* generic_signature() const {
189     return (_generic_signature_index == 0) ?
190       nullptr : symbol_at(_generic_signature_index);
191   }
192   u2 generic_signature_index() const                   { return _generic_signature_index; }
193   void set_generic_signature_index(u2 sig_index)       { _generic_signature_index = sig_index; }
194 
195   // source file name
196   Symbol* source_file_name() const {
197     return (_source_file_name_index == 0) ?
198       nullptr : symbol_at(_source_file_name_index);
199   }
200   u2 source_file_name_index() const                    { return _source_file_name_index; }
201   void set_source_file_name_index(u2 sourcefile_index) { _source_file_name_index = sourcefile_index; }
202 
203   void copy_fields(const ConstantPool* orig);
204 
205   // Redefine classes support.  If a method referring to this constant pool
206   // is on the executing stack, or as a handle in vm code, this constant pool
207   // can't be removed from the set of previous versions saved in the instance
208   // class.
209   bool on_stack() const;
210   bool is_maybe_on_stack() const;
211   void set_on_stack(const bool value);
212 
213   // Faster than MetaspaceObj::is_shared() - used by set_on_stack()
214   bool is_shared() const                     { return (_flags & _is_shared) != 0; }
215 
216   bool has_dynamic_constant() const       { return (_flags & _has_dynamic_constant) != 0; }
217   void set_has_dynamic_constant()         { _flags |= _has_dynamic_constant; }
218 
219   bool is_for_method_handle_intrinsic() const  { return (_flags & _is_for_method_handle_intrinsic) != 0; }
220   void set_is_for_method_handle_intrinsic()    { _flags |= _is_for_method_handle_intrinsic; }
221 
222   // Klass holding pool
223   InstanceKlass* pool_holder() const      { return _pool_holder; }
224   void set_pool_holder(InstanceKlass* k)  { _pool_holder = k; }
225   InstanceKlass** pool_holder_addr()      { return &_pool_holder; }
226 
227   // Interpreter runtime support
228   ConstantPoolCache* cache() const        { return _cache; }
229   void set_cache(ConstantPoolCache* cache){ _cache = cache; }
230 
231   virtual void metaspace_pointers_do(MetaspaceClosure* iter);
232   virtual MetaspaceObj::Type type() const { return ConstantPoolType; }
233 
234   // Create object cache in the constant pool
235   void initialize_resolved_references(ClassLoaderData* loader_data,
236                                       const intStack& reference_map,
237                                       int constant_pool_map_length,
238                                       TRAPS);
239 
240   // resolved strings, methodHandles and callsite objects from the constant pool
241   objArrayOop resolved_references()  const;
242   objArrayOop resolved_references_or_null()  const;
243   oop resolved_reference_at(int obj_index) const;
244   oop set_resolved_reference_at(int index, oop new_value);
245 
246   // mapping resolved object array indexes to cp indexes and back.
247   int object_to_cp_index(int index)         { return reference_map()->at(index); }
248   int cp_to_object_index(int index);
249 
250   void set_resolved_klasses(Array<Klass*>* rk)  { _resolved_klasses = rk; }
251   Array<Klass*>* resolved_klasses() const       { return _resolved_klasses; }
252   void allocate_resolved_klasses(ClassLoaderData* loader_data, int num_klasses, TRAPS);
253   void initialize_unresolved_klasses(ClassLoaderData* loader_data, TRAPS);
254 
255   // Invokedynamic indexes.
256   // They must look completely different from normal indexes.
257   // The main reason is that byte swapping is sometimes done on normal indexes.
258   // Finally, it is helpful for debugging to tell the two apart.
259   static bool is_invokedynamic_index(int i) { return (i < 0); }
260   static int  decode_invokedynamic_index(int i) { assert(is_invokedynamic_index(i),  ""); return ~i; }
261   static int  encode_invokedynamic_index(int i) { assert(!is_invokedynamic_index(i), ""); return ~i; }
262 
263   // Given the per-instruction index of an indy instruction, report the
264   // main constant pool entry for its bootstrap specifier.
265   // From there, uncached_name/signature_ref_at will get the name/type.
266   inline u2 invokedynamic_bootstrap_ref_index_at(int indy_index) const;
267 
268   // Assembly code support
269   static ByteSize tags_offset()         { return byte_offset_of(ConstantPool, _tags); }
270   static ByteSize cache_offset()        { return byte_offset_of(ConstantPool, _cache); }
271   static ByteSize pool_holder_offset()  { return byte_offset_of(ConstantPool, _pool_holder); }
272   static ByteSize resolved_klasses_offset()    { return byte_offset_of(ConstantPool, _resolved_klasses); }
273 
274   // Storing constants
275 
276   // For temporary use while constructing constant pool
277   void klass_index_at_put(int cp_index, int name_index) {
278     tag_at_put(cp_index, JVM_CONSTANT_ClassIndex);
279     *int_at_addr(cp_index) = name_index;
280   }
281 
282   // Hidden class support:
283   void klass_at_put(int class_index, Klass* k);
284 
285   void unresolved_klass_at_put(int cp_index, int name_index, int resolved_klass_index) {
286     release_tag_at_put(cp_index, JVM_CONSTANT_UnresolvedClass);
287 
288     assert((name_index & 0xffff0000) == 0, "must be");
289     assert((resolved_klass_index & 0xffff0000) == 0, "must be");
290     *int_at_addr(cp_index) =
291       build_int_from_shorts((jushort)resolved_klass_index, (jushort)name_index);
292   }
293 
294   void method_handle_index_at_put(int cp_index, int ref_kind, int ref_index) {
295     tag_at_put(cp_index, JVM_CONSTANT_MethodHandle);
296     *int_at_addr(cp_index) = ((jint) ref_index<<16) | ref_kind;
297   }
298 
299   void method_type_index_at_put(int cp_index, int ref_index) {
300     tag_at_put(cp_index, JVM_CONSTANT_MethodType);
301     *int_at_addr(cp_index) = ref_index;
302   }
303 
304   void dynamic_constant_at_put(int cp_index, int bsms_attribute_index, int name_and_type_index) {
305     tag_at_put(cp_index, JVM_CONSTANT_Dynamic);
306     *int_at_addr(cp_index) = ((jint) name_and_type_index<<16) | bsms_attribute_index;
307   }
308 
309   void invoke_dynamic_at_put(int cp_index, int bsms_attribute_index, int name_and_type_index) {
310     tag_at_put(cp_index, JVM_CONSTANT_InvokeDynamic);
311     *int_at_addr(cp_index) = ((jint) name_and_type_index<<16) | bsms_attribute_index;
312   }
313 
314   void unresolved_string_at_put(int cp_index, Symbol* s) {
315     assert(s->refcount() != 0, "should have nonzero refcount");
316     // Note that release_tag_at_put is not needed here because this is called only
317     // when constructing a ConstantPool in a single thread, with no possibility
318     // of concurrent access.
319     tag_at_put(cp_index, JVM_CONSTANT_String);
320     *symbol_at_addr(cp_index) = s;
321   }
322 
323   void int_at_put(int cp_index, jint i) {
324     tag_at_put(cp_index, JVM_CONSTANT_Integer);
325     *int_at_addr(cp_index) = i;
326   }
327 
328   void long_at_put(int cp_index, jlong l) {
329     tag_at_put(cp_index, JVM_CONSTANT_Long);
330     // *long_at_addr(which) = l;
331     Bytes::put_native_u8((address)long_at_addr(cp_index), *((u8*) &l));
332   }
333 
334   void float_at_put(int cp_index, jfloat f) {
335     tag_at_put(cp_index, JVM_CONSTANT_Float);
336     *float_at_addr(cp_index) = f;
337   }
338 
339   void double_at_put(int cp_index, jdouble d) {
340     tag_at_put(cp_index, JVM_CONSTANT_Double);
341     // *double_at_addr(which) = d;
342     // u8 temp = *(u8*) &d;
343     Bytes::put_native_u8((address) double_at_addr(cp_index), *((u8*) &d));
344   }
345 
346   Symbol** symbol_at_addr(int cp_index) const {
347     assert(is_within_bounds(cp_index), "index out of bounds");
348     return (Symbol**) &base()[cp_index];
349   }
350 
351   void symbol_at_put(int cp_index, Symbol* s) {
352     assert(s->refcount() != 0, "should have nonzero refcount");
353     tag_at_put(cp_index, JVM_CONSTANT_Utf8);
354     *symbol_at_addr(cp_index) = s;
355   }
356 
357   void string_at_put(int obj_index, oop str);
358 
359   // For temporary use while constructing constant pool
360   void string_index_at_put(int cp_index, int string_index) {
361     tag_at_put(cp_index, JVM_CONSTANT_StringIndex);
362     *int_at_addr(cp_index) = string_index;
363   }
364 
365   void field_at_put(int cp_index, int class_index, int name_and_type_index) {
366     tag_at_put(cp_index, JVM_CONSTANT_Fieldref);
367     *int_at_addr(cp_index) = ((jint) name_and_type_index<<16) | class_index;
368   }
369 
370   void method_at_put(int cp_index, int class_index, int name_and_type_index) {
371     tag_at_put(cp_index, JVM_CONSTANT_Methodref);
372     *int_at_addr(cp_index) = ((jint) name_and_type_index<<16) | class_index;
373   }
374 
375   void interface_method_at_put(int cp_index, int class_index, int name_and_type_index) {
376     tag_at_put(cp_index, JVM_CONSTANT_InterfaceMethodref);
377     *int_at_addr(cp_index) = ((jint) name_and_type_index<<16) | class_index;  // Not so nice
378   }
379 
380   void name_and_type_at_put(int cp_index, int name_index, int signature_index) {
381     tag_at_put(cp_index, JVM_CONSTANT_NameAndType);
382     *int_at_addr(cp_index) = ((jint) signature_index<<16) | name_index;  // Not so nice
383   }
384 
385   // Tag query
386 
387   constantTag tag_at(int cp_index) const { return (constantTag)tags()->at_acquire(cp_index); }
388 
389   // Fetching constants
390 
391   Klass* klass_at(int cp_index, TRAPS) {
392     constantPoolHandle h_this(THREAD, this);
393     return klass_at_impl(h_this, cp_index, THREAD);
394   }
395 
396   CPKlassSlot klass_slot_at(int cp_index) const {
397     assert(tag_at(cp_index).is_unresolved_klass() || tag_at(cp_index).is_klass(),
398            "Corrupted constant pool");
399     int value = *int_at_addr(cp_index);
400     int name_index = extract_high_short_from_int(value);
401     int resolved_klass_index = extract_low_short_from_int(value);
402     return CPKlassSlot(name_index, resolved_klass_index);
403   }
404 
405   Symbol* klass_name_at(int cp_index) const;  // Returns the name, w/o resolving.
406   int klass_name_index_at(int cp_index) const {
407     return klass_slot_at(cp_index).name_index();
408   }
409 
410   Klass* resolved_klass_at(int cp_index) const;  // Used by Compiler
411 
412   // RedefineClasses() API support:
413   Symbol* klass_at_noresolve(int cp_index) { return klass_name_at(cp_index); }
414   void temp_unresolved_klass_at_put(int cp_index, int name_index) {
415     // Used only during constant pool merging for class redefinition. The resolved klass index
416     // will be initialized later by a call to initialize_unresolved_klasses().
417     unresolved_klass_at_put(cp_index, name_index, CPKlassSlot::_temp_resolved_klass_index);
418   }
419 
420   jint int_at(int cp_index) const {
421     assert(tag_at(cp_index).is_int(), "Corrupted constant pool");
422     return *int_at_addr(cp_index);
423   }
424 
425   jlong long_at(int cp_index) {
426     assert(tag_at(cp_index).is_long(), "Corrupted constant pool");
427     // return *long_at_addr(cp_index);
428     u8 tmp = Bytes::get_native_u8((address)&base()[cp_index]);
429     return *((jlong*)&tmp);
430   }
431 
432   jfloat float_at(int cp_index) {
433     assert(tag_at(cp_index).is_float(), "Corrupted constant pool");
434     return *float_at_addr(cp_index);
435   }
436 
437   jdouble double_at(int cp_index) {
438     assert(tag_at(cp_index).is_double(), "Corrupted constant pool");
439     u8 tmp = Bytes::get_native_u8((address)&base()[cp_index]);
440     return *((jdouble*)&tmp);
441   }
442 
443   Symbol* symbol_at(int cp_index) const {
444     assert(tag_at(cp_index).is_utf8(), "Corrupted constant pool");
445     return *symbol_at_addr(cp_index);
446   }
447 
448   oop string_at(int cp_index, int obj_index, TRAPS) {
449     constantPoolHandle h_this(THREAD, this);
450     return string_at_impl(h_this, cp_index, obj_index, THREAD);
451   }
452   oop string_at(int cp_index, TRAPS) {
453     int obj_index = cp_to_object_index(cp_index);
454     return string_at(cp_index, obj_index, THREAD);
455   }
456 
457   // Version that can be used before string oop array is created.
458   oop uncached_string_at(int cp_index, TRAPS);
459 
460   // only called when we are sure a string entry is already resolved (via an
461   // earlier string_at call.
462   oop resolved_string_at(int cp_index) {
463     assert(tag_at(cp_index).is_string(), "Corrupted constant pool");
464     // Must do an acquire here in case another thread resolved the klass
465     // behind our back, lest we later load stale values thru the oop.
466     // we might want a volatile_obj_at in ObjArrayKlass.
467     int obj_index = cp_to_object_index(cp_index);
468     return resolved_reference_at(obj_index);
469   }
470 
471   Symbol* unresolved_string_at(int cp_index) {
472     assert(tag_at(cp_index).is_string(), "Corrupted constant pool");
473     return *symbol_at_addr(cp_index);
474   }
475 
476   // Returns an UTF8 for a CONSTANT_String entry at a given index.
477   // UTF8 char* representation was chosen to avoid conversion of
478   // java_lang_Strings at resolved entries into Symbol*s
479   // or vice versa.
480   char* string_at_noresolve(int cp_index);
481 
482   jint name_and_type_at(int cp_index) {
483     assert(tag_at(cp_index).is_name_and_type(), "Corrupted constant pool");
484     return *int_at_addr(cp_index);
485   }
486 
487   int method_handle_ref_kind_at(int cp_index) {
488     assert(tag_at(cp_index).is_method_handle() ||
489            tag_at(cp_index).is_method_handle_in_error(), "Corrupted constant pool");
490     return extract_low_short_from_int(*int_at_addr(cp_index));  // mask out unwanted ref_index bits
491   }
492   int method_handle_index_at(int cp_index) {
493     assert(tag_at(cp_index).is_method_handle() ||
494            tag_at(cp_index).is_method_handle_in_error(), "Corrupted constant pool");
495     return extract_high_short_from_int(*int_at_addr(cp_index));  // shift out unwanted ref_kind bits
496   }
497   int method_type_index_at(int cp_index) {
498     assert(tag_at(cp_index).is_method_type() ||
499            tag_at(cp_index).is_method_type_in_error(), "Corrupted constant pool");
500     return *int_at_addr(cp_index);
501   }
502 
503   // Derived queries:
504   Symbol* method_handle_name_ref_at(int cp_index) {
505     int member = method_handle_index_at(cp_index);
506     return uncached_name_ref_at(member);
507   }
508   Symbol* method_handle_signature_ref_at(int cp_index) {
509     int member = method_handle_index_at(cp_index);
510     return uncached_signature_ref_at(member);
511   }
512   u2 method_handle_klass_index_at(int cp_index) {
513     int member = method_handle_index_at(cp_index);
514     return uncached_klass_ref_index_at(member);
515   }
516   Symbol* method_type_signature_at(int cp_index) {
517     int sym = method_type_index_at(cp_index);
518     return symbol_at(sym);
519   }
520 
521   u2 bootstrap_name_and_type_ref_index_at(int cp_index) {
522     assert(tag_at(cp_index).has_bootstrap(), "Corrupted constant pool");
523     return extract_high_short_from_int(*int_at_addr(cp_index));
524   }
525   u2 bootstrap_methods_attribute_index(int cp_index) {
526     assert(tag_at(cp_index).has_bootstrap(), "Corrupted constant pool");
527     return extract_low_short_from_int(*int_at_addr(cp_index));
528   }
529   int bootstrap_operand_base(int cp_index) {
530     int bsms_attribute_index = bootstrap_methods_attribute_index(cp_index);
531     return operand_offset_at(operands(), bsms_attribute_index);
532   }
533   // The first part of the operands array consists of an index into the second part.
534   // Extract a 32-bit index value from the first part.
535   static int operand_offset_at(Array<u2>* operands, int bsms_attribute_index) {
536     int n = (bsms_attribute_index * 2);
537     assert(n >= 0 && n+2 <= operands->length(), "oob");
538     // The first 32-bit index points to the beginning of the second part
539     // of the operands array.  Make sure this index is in the first part.
540     DEBUG_ONLY(int second_part = build_int_from_shorts(operands->at(0),
541                                                        operands->at(1)));
542     assert(second_part == 0 || n+2 <= second_part, "oob (2)");
543     int offset = build_int_from_shorts(operands->at(n+0),
544                                        operands->at(n+1));
545     // The offset itself must point into the second part of the array.
546     assert(offset == 0 || (offset >= second_part && offset <= operands->length()), "oob (3)");
547     return offset;
548   }
549   static void operand_offset_at_put(Array<u2>* operands, int bsms_attribute_index, int offset) {
550     int n = bsms_attribute_index * 2;
551     assert(n >= 0 && n+2 <= operands->length(), "oob");
552     operands->at_put(n+0, extract_low_short_from_int(offset));
553     operands->at_put(n+1, extract_high_short_from_int(offset));
554   }
555   static int operand_array_length(Array<u2>* operands) {
556     if (operands == nullptr || operands->length() == 0)  return 0;
557     int second_part = operand_offset_at(operands, 0);
558     return (second_part / 2);
559   }
560 
561 #ifdef ASSERT
562   // operand tuples fit together exactly, end to end
563   static int operand_limit_at(Array<u2>* operands, int bsms_attribute_index) {
564     int nextidx = bsms_attribute_index + 1;
565     if (nextidx == operand_array_length(operands))
566       return operands->length();
567     else
568       return operand_offset_at(operands, nextidx);
569   }
570   int bootstrap_operand_limit(int cp_index) {
571     int bsms_attribute_index = bootstrap_methods_attribute_index(cp_index);
572     return operand_limit_at(operands(), bsms_attribute_index);
573   }
574 #endif //ASSERT
575 
576   // Layout of InvokeDynamic and Dynamic bootstrap method specifier
577   // data in second part of operands array.  This encodes one record in
578   // the BootstrapMethods attribute.  The whole specifier also includes
579   // the name and type information from the main constant pool entry.
580   enum {
581          _indy_bsm_offset  = 0,  // CONSTANT_MethodHandle bsm
582          _indy_argc_offset = 1,  // u2 argc
583          _indy_argv_offset = 2   // u2 argv[argc]
584   };
585 
586   // These functions are used in RedefineClasses for CP merge
587 
588   int operand_offset_at(int bsms_attribute_index) {
589     assert(0 <= bsms_attribute_index &&
590            bsms_attribute_index < operand_array_length(operands()),
591            "Corrupted CP operands");
592     return operand_offset_at(operands(), bsms_attribute_index);
593   }
594   u2 operand_bootstrap_method_ref_index_at(int bsms_attribute_index) {
595     int offset = operand_offset_at(bsms_attribute_index);
596     return operands()->at(offset + _indy_bsm_offset);
597   }
598   u2 operand_argument_count_at(int bsms_attribute_index) {
599     int offset = operand_offset_at(bsms_attribute_index);
600     u2 argc = operands()->at(offset + _indy_argc_offset);
601     return argc;
602   }
603   u2 operand_argument_index_at(int bsms_attribute_index, int j) {
604     int offset = operand_offset_at(bsms_attribute_index);
605     return operands()->at(offset + _indy_argv_offset + j);
606   }
607   int operand_next_offset_at(int bsms_attribute_index) {
608     int offset = operand_offset_at(bsms_attribute_index) + _indy_argv_offset
609                    + operand_argument_count_at(bsms_attribute_index);
610     return offset;
611   }
612   // Compare a bootstrap specifier data in the operands arrays
613   bool compare_operand_to(int bsms_attribute_index1, const constantPoolHandle& cp2,
614                           int bsms_attribute_index2);
615   // Find a bootstrap specifier data in the operands array
616   int find_matching_operand(int bsms_attribute_index, const constantPoolHandle& search_cp,
617                             int operands_cur_len);
618   // Resize the operands array with delta_len and delta_size
619   void resize_operands(int delta_len, int delta_size, TRAPS);
620   // Extend the operands array with the length and size of the ext_cp operands
621   void extend_operands(const constantPoolHandle& ext_cp, TRAPS);
622   // Shrink the operands array to a smaller array with new_len length
623   void shrink_operands(int new_len, TRAPS);
624 
625   u2 bootstrap_method_ref_index_at(int cp_index) {
626     assert(tag_at(cp_index).has_bootstrap(), "Corrupted constant pool");
627     int op_base = bootstrap_operand_base(cp_index);
628     return operands()->at(op_base + _indy_bsm_offset);
629   }
630   u2 bootstrap_argument_count_at(int cp_index) {
631     assert(tag_at(cp_index).has_bootstrap(), "Corrupted constant pool");
632     int op_base = bootstrap_operand_base(cp_index);
633     u2 argc = operands()->at(op_base + _indy_argc_offset);
634     DEBUG_ONLY(int end_offset = op_base + _indy_argv_offset + argc;
635                int next_offset = bootstrap_operand_limit(cp_index));
636     assert(end_offset == next_offset, "matched ending");
637     return argc;
638   }
639   u2 bootstrap_argument_index_at(int cp_index, int j) {
640     int op_base = bootstrap_operand_base(cp_index);
641     DEBUG_ONLY(int argc = operands()->at(op_base + _indy_argc_offset));
642     assert((uint)j < (uint)argc, "oob");
643     return operands()->at(op_base + _indy_argv_offset + j);
644   }
645 
646   // The following methods (name/signature/klass_ref_at, klass_ref_at_noresolve,
647   // name_and_type_ref_index_at) all expect to be passed indices obtained
648   // directly from the bytecode.
649   // If the indices are meant to refer to fields or methods, they are
650   // actually rewritten indices that point to entries in their respective structures
651   // i.e. ResolvedMethodEntries or ResolvedFieldEntries.
652   // The routine to_cp_index manages the adjustment
653   // of these values back to constant pool indices.
654 
655   // There are also "uncached" versions which do not adjust the operand index; see below.
656 
657   // Lookup for entries consisting of (klass_index, name_and_type index)
658   Klass* klass_ref_at(int which, Bytecodes::Code code, TRAPS);
659   Symbol* klass_ref_at_noresolve(int which, Bytecodes::Code code);
660   Symbol* name_ref_at(int which, Bytecodes::Code code) {
661     int name_index = name_ref_index_at(name_and_type_ref_index_at(which, code));
662     return symbol_at(name_index);
663   }
664   Symbol* signature_ref_at(int which, Bytecodes::Code code) {
665     int signature_index = signature_ref_index_at(name_and_type_ref_index_at(which, code));
666     return symbol_at(signature_index);
667   }
668 
669   u2 klass_ref_index_at(int which, Bytecodes::Code code);
670   u2 name_and_type_ref_index_at(int which, Bytecodes::Code code);
671 
672   constantTag tag_ref_at(int cp_cache_index, Bytecodes::Code code);
673 
674   int to_cp_index(int which, Bytecodes::Code code);
675 
676   // Lookup for entries consisting of (name_index, signature_index)
677   u2 name_ref_index_at(int cp_index);            // ==  low-order jshort of name_and_type_at(cp_index)
678   u2 signature_ref_index_at(int cp_index);       // == high-order jshort of name_and_type_at(cp_index)
679 
680   BasicType basic_type_for_signature_at(int cp_index) const;
681 
682   // Resolve string constants (to prevent allocation during compilation)
683   void resolve_string_constants(TRAPS) {
684     constantPoolHandle h_this(THREAD, this);
685     resolve_string_constants_impl(h_this, CHECK);
686   }
687 
688 #if INCLUDE_CDS
689   // CDS support
690   objArrayOop prepare_resolved_references_for_archiving() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
691   void add_dumped_interned_strings() NOT_CDS_JAVA_HEAP_RETURN;
692   bool can_archive_invokehandle(ResolvedMethodEntry* rme);
693   bool maybe_archive_resolved_klass_at(int cp_index);
694   bool can_archive_resolved_method(ResolvedMethodEntry* method_entry);
695   void archive_entries();
696   void remove_unshareable_info();
697   void restore_unshareable_info(TRAPS);
698 #endif
699 
700  private:
701   enum { _no_index_sentinel = -1, _possible_index_sentinel = -2 };
702  public:
703 
704   // Get the tag for a constant, which may involve a constant dynamic
705   constantTag constant_tag_at(int cp_index);
706   // Get the basic type for a constant, which may involve a constant dynamic
707   BasicType basic_type_for_constant_at(int cp_index);
708 
709   // Resolve late bound constants.
710   oop resolve_constant_at(int cp_index, TRAPS) {
711     constantPoolHandle h_this(THREAD, this);
712     return resolve_constant_at_impl(h_this, cp_index, _no_index_sentinel, nullptr, THREAD);
713   }
714 
715   oop resolve_cached_constant_at(int cache_index, TRAPS) {
716     constantPoolHandle h_this(THREAD, this);
717     return resolve_constant_at_impl(h_this, _no_index_sentinel, cache_index, nullptr, THREAD);
718   }
719 
720   oop resolve_possibly_cached_constant_at(int cp_index, TRAPS) {
721     constantPoolHandle h_this(THREAD, this);
722     return resolve_constant_at_impl(h_this, cp_index, _possible_index_sentinel, nullptr, THREAD);
723   }
724 
725   oop find_cached_constant_at(int cp_index, bool& found_it, TRAPS) {
726     constantPoolHandle h_this(THREAD, this);
727     return resolve_constant_at_impl(h_this, cp_index, _possible_index_sentinel, &found_it, THREAD);
728   }
729 
730   void copy_bootstrap_arguments_at(int cp_index,
731                                    int start_arg, int end_arg,
732                                    objArrayHandle info, int pos,
733                                    bool must_resolve, Handle if_not_available, TRAPS) {
734     constantPoolHandle h_this(THREAD, this);
735     copy_bootstrap_arguments_at_impl(h_this, cp_index, start_arg, end_arg,
736                                      info, pos, must_resolve, if_not_available, THREAD);
737   }
738 
739   // Klass name matches name at offset
740   bool klass_name_at_matches(const InstanceKlass* k, int cp_index);
741 
742   // Sizing
743   int length() const                   { return _length; }
744   void set_length(int length)          { _length = length; }
745 
746   // Tells whether index is within bounds.
747   bool is_within_bounds(int index) const {
748     return 0 <= index && index < length();
749   }
750 
751   // Sizing (in words)
752   static int header_size()             {
753     return align_up((int)sizeof(ConstantPool), wordSize) / wordSize;
754   }
755   static int size(int length)          { return align_metadata_size(header_size() + length); }
756   int size() const                     { return size(length()); }
757 
758   // ConstantPools should be stored in the read-only region of CDS archive.
759   static bool is_read_only_by_default() { return true; }
760 
761   friend class ClassFileParser;
762   friend class SystemDictionary;
763 
764   // Used by CDS. These classes need to access the private ConstantPool() constructor.
765   template <class T> friend class CppVtableTesterA;
766   template <class T> friend class CppVtableTesterB;
767   template <class T> friend class CppVtableCloner;
768 
769   // Used by compiler to prevent classloading.
770   static Method*          method_at_if_loaded      (const constantPoolHandle& this_cp, int which);
771   static bool       has_appendix_at_if_loaded      (const constantPoolHandle& this_cp, int which);
772   static oop            appendix_at_if_loaded      (const constantPoolHandle& this_cp, int which);
773   static bool has_local_signature_at_if_loaded     (const constantPoolHandle& this_cp, int which);
774   static Klass*            klass_at_if_loaded      (const constantPoolHandle& this_cp, int which);
775 
776   // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the
777   // future by other Java code. These take constant pool indices rather than
778   // constant pool cache indices as do the peer methods above.
779   Symbol* uncached_klass_ref_at_noresolve(int cp_index);
780   Symbol* uncached_name_ref_at(int cp_index) {
781     int name_index = name_ref_index_at(uncached_name_and_type_ref_index_at(cp_index));
782     return symbol_at(name_index);
783   }
784   Symbol* uncached_signature_ref_at(int cp_index) {
785     int signature_index = signature_ref_index_at(uncached_name_and_type_ref_index_at(cp_index));
786     return symbol_at(signature_index);
787   }
788   u2 uncached_klass_ref_index_at(int cp_index);
789   u2 uncached_name_and_type_ref_index_at(int cp_index);
790 
791   // Sharing
792   int pre_resolve_shared_klasses(TRAPS);
793 
794   // Debugging
795   const char* printable_name_at(int cp_index) PRODUCT_RETURN0;
796 
797  private:
798 
799   void set_resolved_references(OopHandle s) { _cache->set_resolved_references(s); }
800   Array<u2>* reference_map() const        {  return (_cache == nullptr) ? nullptr :  _cache->reference_map(); }
801   void set_reference_map(Array<u2>* o)    { _cache->set_reference_map(o); }
802 
803   // Used while constructing constant pool (only by ClassFileParser)
804   jint klass_index_at(int cp_index) {
805     assert(tag_at(cp_index).is_klass_index(), "Corrupted constant pool");
806     return *int_at_addr(cp_index);
807   }
808 
809   jint string_index_at(int cp_index) {
810     assert(tag_at(cp_index).is_string_index(), "Corrupted constant pool");
811     return *int_at_addr(cp_index);
812   }
813 
814   // Performs the LinkResolver checks
815   static void verify_constant_pool_resolve(const constantPoolHandle& this_cp, Klass* klass, TRAPS);
816 
817   // Implementation of methods that needs an exposed 'this' pointer, in order to
818   // handle GC while executing the method
819   static Klass* klass_at_impl(const constantPoolHandle& this_cp, int cp_index, TRAPS);
820   static oop string_at_impl(const constantPoolHandle& this_cp, int cp_index, int obj_index, TRAPS);
821 
822   static void trace_class_resolution(const constantPoolHandle& this_cp, Klass* k);
823 
824   // Resolve string constants (to prevent allocation during compilation)
825   static void resolve_string_constants_impl(const constantPoolHandle& this_cp, TRAPS);
826 
827   static oop resolve_constant_at_impl(const constantPoolHandle& this_cp, int cp_index, int cache_index,
828                                       bool* status_return, TRAPS);
829   static void copy_bootstrap_arguments_at_impl(const constantPoolHandle& this_cp, int cp_index,
830                                                int start_arg, int end_arg,
831                                                objArrayHandle info, int pos,
832                                                bool must_resolve, Handle if_not_available, TRAPS);
833 
834   // Exception handling
835   static void save_and_throw_exception(const constantPoolHandle& this_cp, int cp_index, constantTag tag, TRAPS);
836 
837  public:
838   // Exception handling
839   static void throw_resolution_error(const constantPoolHandle& this_cp, int which, TRAPS);
840 
841   // Merging ConstantPool* support:
842   bool compare_entry_to(int index1, const constantPoolHandle& cp2, int index2);
843   void copy_cp_to(int start_cpi, int end_cpi, const constantPoolHandle& to_cp, int to_cpi, TRAPS) {
844     constantPoolHandle h_this(THREAD, this);
845     copy_cp_to_impl(h_this, start_cpi, end_cpi, to_cp, to_cpi, THREAD);
846   }
847   static void copy_cp_to_impl(const constantPoolHandle& from_cp, int start_cpi, int end_cpi, const constantPoolHandle& to_cp, int to_cpi, TRAPS);
848   static void copy_entry_to(const constantPoolHandle& from_cp, int from_cpi, const constantPoolHandle& to_cp, int to_cpi);
849   static void copy_operands(const constantPoolHandle& from_cp, const constantPoolHandle& to_cp, TRAPS);
850   int  find_matching_entry(int pattern_i, const constantPoolHandle& search_cp);
851   int  version() const                    { return _saved._version; }
852   void set_version(int version)           { _saved._version = version; }
853   void increment_and_save_version(int version) {
854     _saved._version = version >= 0 ? (version + 1) : version;  // keep overflow
855   }
856 
857   void set_resolved_reference_length(int length) { _saved._resolved_reference_length = length; }
858   int  resolved_reference_length() const  { return _saved._resolved_reference_length; }
859 
860   // Decrease ref counts of symbols that are in the constant pool
861   // when the holder class is unloaded
862   void unreference_symbols();
863 
864   // Deallocate constant pool for RedefineClasses
865   void deallocate_contents(ClassLoaderData* loader_data);
866   void release_C_heap_structures();
867 
868   // JVMTI access - GetConstantPool, RetransformClasses, ...
869   friend class JvmtiConstantPoolReconstituter;
870 
871  private:
872   class SymbolHash: public CHeapObj<mtSymbol> {
873     ResourceHashtable<const Symbol*, u2, 256, AnyObj::C_HEAP, mtSymbol, Symbol::compute_hash> _table;
874 
875    public:
876     void add_if_absent(const Symbol* sym, u2 value) {
877       bool created;
878       _table.put_if_absent(sym, value, &created);
879     }
880 
881     u2 symbol_to_value(const Symbol* sym) {
882       u2* value = _table.get(sym);
883       return (value == nullptr) ? 0 : *value;
884     }
885   }; // End SymbolHash class
886 
887   jint cpool_entry_size(jint idx);
888   jint hash_entries_to(SymbolHash *symmap, SymbolHash *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                         SymbolHash* 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   // ResolvedFieldEntry getters
911   inline ResolvedFieldEntry* resolved_field_entry_at(int field_index);
912   inline int resolved_field_entries_length() const;
913 
914   // ResolvedMethodEntry getters
915   inline ResolvedMethodEntry* resolved_method_entry_at(int method_index);
916   inline int resolved_method_entries_length() const;
917   inline oop appendix_if_resolved(int method_index) const;
918 
919   // ResolvedIndyEntry getters
920   inline ResolvedIndyEntry* resolved_indy_entry_at(int index);
921   inline int resolved_indy_entries_length() const;
922   inline oop resolved_reference_from_indy(int index) const;
923   inline oop resolved_reference_from_method(int index) const;
924 };
925 
926 #endif // SHARE_OOPS_CONSTANTPOOL_HPP