1 /*
  2  * Copyright (c) 1998, 2021, 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_CPCACHE_HPP
 26 #define SHARE_OOPS_CPCACHE_HPP
 27 
 28 #include "interpreter/bytecodes.hpp"
 29 #include "memory/allocation.hpp"
 30 #include "oops/array.hpp"
 31 #include "oops/oopHandle.hpp"
 32 #include "runtime/handles.hpp"
 33 #include "utilities/align.hpp"
 34 #include "utilities/constantTag.hpp"
 35 #include "utilities/growableArray.hpp"
 36 
 37 // The ConstantPoolCache is not a cache! It is the resolution table that the
 38 // interpreter uses to avoid going into the runtime and a way to access resolved
 39 // values.
 40 
 41 // A ConstantPoolCacheEntry describes an individual entry of the constant
 42 // pool cache. There's 2 principal kinds of entries: field entries for in-
 43 // stance & static field access, and method entries for invokes. Some of
 44 // the entry layout is shared and looks as follows:
 45 //
 46 // bit number |31                0|
 47 // bit length |-8--|-8--|---16----|
 48 // --------------------------------
 49 // _indices   [ b2 | b1 |  index  ]  index = constant_pool_index
 50 // _f1        [  entry specific   ]  metadata ptr (method or klass)
 51 // _f2        [  entry specific   ]  vtable or res_ref index, or vfinal method ptr
 52 // _flags     [tos|0|F=1|0|0|0|f|v|0 |0000|field_index] (for field entries)
 53 // bit length [ 4 |1| 1 |1|1|1|1|1|1 |1     |-3-|----16-----]
 54 // _flags     [tos|0|F=0|S|A|I|f|0|vf|indy_rf|000|00000|psize] (for method entries)
 55 // bit length [ 4 |1| 1 |1|1|1|1|1|1 |-4--|--8--|--8--]
 56 
 57 // --------------------------------
 58 //
 59 // with:
 60 // index  = original constant pool index
 61 // b1     = bytecode 1
 62 // b2     = bytecode 2
 63 // psize  = parameters size (method entries only)
 64 // field_index = index into field information in holder InstanceKlass
 65 //          The index max is 0xffff (max number of fields in constant pool)
 66 //          and is multiplied by (InstanceKlass::next_offset) when accessing.
 67 // tos    = TosState
 68 // F      = the entry is for a field (or F=0 for a method)
 69 // A      = call site has an appendix argument (loaded from resolved references)
 70 // I      = interface call is forced virtual (must use a vtable index or vfinal)
 71 // f      = field or method is final
 72 // v      = field is volatile
 73 // vf     = virtual but final (method entries only: is_vfinal())
 74 // indy_rf = call site specifier method resolution failed
 75 //
 76 // The flags after TosState have the following interpretation:
 77 // bit 27: 0 for fields, 1 for methods
 78 // f  flag true if field is marked final
 79 // v  flag true if field is volatile (only for fields)
 80 // f2 flag true if f2 contains an oop (e.g., virtual final method)
 81 // fv flag true if invokeinterface used for method in class Object
 82 //
 83 // The flags 31, 30, 29, 28 together build a 4 bit number 0 to 16 with the
 84 // following mapping to the TosState states:
 85 //
 86 // btos: 0
 87 // ztos: 1
 88 // ctos: 2
 89 // stos: 3
 90 // itos: 4
 91 // ltos: 5
 92 // ftos: 6
 93 // dtos: 7
 94 // atos: 8
 95 // vtos: 9
 96 //
 97 // Entry specific: field entries:
 98 // _indices = get (b1 section) and put (b2 section) bytecodes, original constant pool index
 99 // _f1      = field holder (as a java.lang.Class, not a Klass*)
100 // _f2      = field offset in bytes
101 // _flags   = field type information, original FieldInfo index in field holder
102 //            (field_index section)
103 //
104 // Entry specific: method entries:
105 // _indices = invoke code for f1 (b1 section), invoke code for f2 (b2 section),
106 //            original constant pool index
107 // _f1      = Method* for non-virtual calls, unused by virtual calls.
108 //            for interface calls, which are essentially virtual but need a klass,
109 //            contains Klass* for the corresponding interface.
110 //            for invokedynamic and invokehandle, f1 contains the adapter method which
111 //            manages the actual call. The appendix is stored in the ConstantPool
112 //            resolved_references array.
113 //            (upcoming metadata changes will move the appendix to a separate array)
114 // _f2      = vtable/itable index (or final Method*) for virtual calls only,
115 //            unused by non-virtual.  The is_vfinal flag indicates this is a
116 //            method pointer for a final method, not an index.
117 // _flags   = has local signature (MHs and indy),
118 //            virtual final bit (vfinal),
119 //            parameter size (psize section)
120 //
121 // Note: invokevirtual & invokespecial bytecodes can share the same constant
122 //       pool entry and thus the same constant pool cache entry. All invoke
123 //       bytecodes but invokevirtual use only _f1 and the corresponding b1
124 //       bytecode, while invokevirtual uses only _f2 and the corresponding
125 //       b2 bytecode.  The value of _flags is shared for both types of entries.
126 //
127 // The fields are volatile so that they are stored in the order written in the
128 // source code.  The _indices field with the bytecode must be written last.
129 
130 class CallInfo;
131 
132 class ConstantPoolCacheEntry {
133   friend class VMStructs;
134   friend class constantPoolCacheKlass;
135   friend class ConstantPool;
136   friend class InterpreterRuntime;
137 
138  private:
139   volatile intx     _indices;  // constant pool index & rewrite bytecodes
140   Metadata* volatile   _f1;       // entry specific metadata field
141   volatile intx        _f2;       // entry specific int/metadata field
142   volatile intx     _flags;    // flags
143 
144 
145   void set_bytecode_1(Bytecodes::Code code);
146   void set_bytecode_2(Bytecodes::Code code);
147   void set_f1(Metadata* f1) {
148     Metadata* existing_f1 = _f1; // read once
149     assert(existing_f1 == NULL || existing_f1 == f1, "illegal field change");
150     _f1 = f1;
151   }
152   void release_set_f1(Metadata* f1);
153   void set_f2(intx f2) {
154     intx existing_f2 = _f2; // read once
155     assert(existing_f2 == 0 || existing_f2 == f2, "illegal field change");
156     _f2 = f2;
157   }
158   void set_f2_as_vfinal_method(Method* f2) {
159     assert(is_vfinal(), "flags must be set");
160     set_f2((intx)f2);
161   }
162   int make_flags(TosState state, int option_bits, int field_index_or_method_params);
163   void set_flags(intx flags)                     { _flags = flags; }
164   void set_field_flags(TosState field_type, int option_bits, int field_index) {
165     assert((field_index & field_index_mask) == field_index, "field_index in range");
166     set_flags(make_flags(field_type, option_bits | (1 << is_field_entry_shift), field_index));
167   }
168   void set_method_flags(TosState return_type, int option_bits, int method_params) {
169     assert((method_params & parameter_size_mask) == method_params, "method_params in range");
170     set_flags(make_flags(return_type, option_bits, method_params));
171   }
172 
173  public:
174   // specific bit definitions for the flags field:
175   // (Note: the interpreter must use these definitions to access the CP cache.)
176   enum {
177     // high order bits are the TosState corresponding to field type or method return type
178     tos_state_bits             = 4,
179     tos_state_mask             = right_n_bits(tos_state_bits),
180     tos_state_shift            = BitsPerInt - tos_state_bits,  // see verify_tos_state_shift below
181     // misc. option bits; can be any bit position in [16..27]
182     is_field_entry_shift       = 26,  // (F) is it a field or a method?
183     has_local_signature_shift  = 25,  // (S) does the call site have a per-site signature (sig-poly methods)?
184     has_appendix_shift         = 24,  // (A) does the call site have an appendix argument?
185     is_forced_virtual_shift    = 23,  // (I) is the interface reference forced to virtual mode?
186     is_final_shift             = 22,  // (f) is the field or method final?
187     is_volatile_shift          = 21,  // (v) is the field volatile?
188     is_vfinal_shift            = 20,  // (vf) did the call resolve to a final method?
189     indy_resolution_failed_shift= 19, // (indy_rf) did call site specifier resolution fail ?
190     // low order bits give field index (for FieldInfo) or method parameter size:
191     field_index_bits           = 16,
192     field_index_mask           = right_n_bits(field_index_bits),
193     parameter_size_bits        = 8,  // subset of field_index_mask, range is 0..255
194     parameter_size_mask        = right_n_bits(parameter_size_bits),
195     option_bits_mask           = ~(((~0u) << tos_state_shift) | (field_index_mask | parameter_size_mask))
196   };
197 
198   // specific bit definitions for the indices field:
199   enum {
200     cp_index_bits              = 2*BitsPerByte,
201     cp_index_mask              = right_n_bits(cp_index_bits),
202     bytecode_1_shift           = cp_index_bits,
203     bytecode_1_mask            = right_n_bits(BitsPerByte), // == (u1)0xFF
204     bytecode_2_shift           = cp_index_bits + BitsPerByte,
205     bytecode_2_mask            = right_n_bits(BitsPerByte)  // == (u1)0xFF
206   };
207 
208 
209   // Initialization
210   void initialize_entry(int original_index);     // initialize primary entry
211   void initialize_resolved_reference_index(int ref_index) {
212     assert(_f2 == 0, "set once");  // note: ref_index might be zero also
213     _f2 = ref_index;
214   }
215 
216   void set_field(                                // sets entry to resolved field state
217     Bytecodes::Code get_code,                    // the bytecode used for reading the field
218     Bytecodes::Code put_code,                    // the bytecode used for writing the field
219     Klass*          field_holder,                // the object/klass holding the field
220     int             orig_field_index,            // the original field index in the field holder
221     int             field_offset,                // the field offset in words in the field holder
222     TosState        field_type,                  // the (machine) field type
223     bool            is_final,                    // the field is final
224     bool            is_volatile                  // the field is volatile
225   );
226 
227  private:
228   void set_direct_or_vtable_call(
229     Bytecodes::Code invoke_code,                 // the bytecode used for invoking the method
230     const methodHandle& method,                  // the method/prototype if any (NULL, otherwise)
231     int             vtable_index,                // the vtable index if any, else negative
232     bool            sender_is_interface
233   );
234 
235  public:
236   void set_direct_call(                          // sets entry to exact concrete method entry
237     Bytecodes::Code invoke_code,                 // the bytecode used for invoking the method
238     const methodHandle& method,                  // the method to call
239     bool            sender_is_interface
240   );
241 
242   void set_vtable_call(                          // sets entry to vtable index
243     Bytecodes::Code invoke_code,                 // the bytecode used for invoking the method
244     const methodHandle& method,                  // resolved method which declares the vtable index
245     int             vtable_index                 // the vtable index
246   );
247 
248   void set_itable_call(
249     Bytecodes::Code invoke_code,                 // the bytecode used; must be invokeinterface
250     Klass* referenced_klass,                     // the referenced klass in the InterfaceMethodref
251     const methodHandle& method,                  // the resolved interface method
252     int itable_index                             // index into itable for the method
253   );
254 
255   void set_method_handle(
256     const constantPoolHandle& cpool,             // holding constant pool (required for locking)
257     const CallInfo &call_info                    // Call link information
258   );
259 
260   void set_dynamic_call(
261     const constantPoolHandle& cpool,             // holding constant pool (required for locking)
262     const CallInfo &call_info                    // Call link information
263   );
264 
265   // Common code for invokedynamic and MH invocations.
266 
267   // The "appendix" is an optional call-site-specific parameter which is
268   // pushed by the JVM at the end of the argument list.  This argument may
269   // be a MethodType for the MH.invokes and a CallSite for an invokedynamic
270   // instruction.  However, its exact type and use depends on the Java upcall,
271   // which simply returns a compiled LambdaForm along with any reference
272   // that LambdaForm needs to complete the call.  If the upcall returns a
273   // null appendix, the argument is not passed at all.
274   //
275   // The appendix is *not* represented in the signature of the symbolic
276   // reference for the call site, but (if present) it *is* represented in
277   // the Method* bound to the site.  This means that static and dynamic
278   // resolution logic needs to make slightly different assessments about the
279   // number and types of arguments.
280   void set_method_handle_common(
281     const constantPoolHandle& cpool,                    // holding constant pool (required for locking)
282     Bytecodes::Code invoke_code,                 // _invokehandle or _invokedynamic
283     const CallInfo &call_info                    // Call link information
284   );
285 
286   // Return TRUE if resolution failed and this thread got to record the failure
287   // status.  Return FALSE if another thread succeeded or failed in resolving
288   // the method and recorded the success or failure before this thread had a
289   // chance to record its failure.
290   bool save_and_throw_indy_exc(const constantPoolHandle& cpool, int cpool_index,
291                                int index, constantTag tag, TRAPS);
292 
293   // invokedynamic and invokehandle call sites have an "appendix" item in the
294   // resolved references array.
295   Method*      method_if_resolved(const constantPoolHandle& cpool);
296   oop        appendix_if_resolved(const constantPoolHandle& cpool);
297 
298   void set_parameter_size(int value);
299 
300   // Which bytecode number (1 or 2) in the index field is valid for this bytecode?
301   // Returns -1 if neither is valid.
302   static int bytecode_number(Bytecodes::Code code) {
303     switch (code) {
304       case Bytecodes::_getstatic       :    // fall through
305       case Bytecodes::_getfield        :    // fall through
306       case Bytecodes::_invokespecial   :    // fall through
307       case Bytecodes::_invokestatic    :    // fall through
308       case Bytecodes::_invokehandle    :    // fall through
309       case Bytecodes::_invokedynamic   :    // fall through
310       case Bytecodes::_invokeinterface : return 1;
311       case Bytecodes::_putstatic       :    // fall through
312       case Bytecodes::_putfield        :    // fall through
313       case Bytecodes::_invokevirtual   : return 2;
314       default                          : break;
315     }
316     return -1;
317   }
318 
319   // Has this bytecode been resolved? Only valid for invokes and get/put field/static.
320   bool is_resolved(Bytecodes::Code code) const;
321 
322   // Accessors
323   int indices() const                            { return _indices; }
324   int indices_ord() const;
325   int constant_pool_index() const                { return (indices() & cp_index_mask); }
326   Bytecodes::Code bytecode_1() const;
327   Bytecodes::Code bytecode_2() const;
328   Metadata* f1_ord() const;
329   Method*   f1_as_method() const;
330   Klass*    f1_as_klass() const;
331   // Use the accessor f1() to acquire _f1's value. This is needed for
332   // example in BytecodeInterpreter::run(), where is_f1_null() is
333   // called to check if an invokedynamic call is resolved. This load
334   // of _f1 must be ordered with the loads performed by
335   // cache->main_entry_index().
336   bool      is_f1_null() const;  // classifies a CPC entry as unbound
337   int       f2_as_index() const                  { assert(!is_vfinal(), ""); return (int) _f2; }
338   Method*   f2_as_vfinal_method() const          { assert(is_vfinal(), ""); return (Method*)_f2; }
339   Method*   f2_as_interface_method() const;
340   intx flags_ord() const;
341   int  field_index() const                       { assert(is_field_entry(),  ""); return (_flags & field_index_mask); }
342   int  parameter_size() const                    { assert(is_method_entry(), ""); return (_flags & parameter_size_mask); }
343   bool is_volatile() const                       { return (_flags & (1 << is_volatile_shift))       != 0; }
344   bool is_final() const                          { return (_flags & (1 << is_final_shift))          != 0; }
345   bool is_forced_virtual() const                 { return (_flags & (1 << is_forced_virtual_shift)) != 0; }
346   bool is_vfinal() const                         { return (_flags & (1 << is_vfinal_shift))         != 0; }
347   bool indy_resolution_failed() const;
348   bool has_appendix() const;
349   bool has_local_signature() const;
350   bool is_method_entry() const                   { return (_flags & (1 << is_field_entry_shift))    == 0; }
351   bool is_field_entry() const                    { return (_flags & (1 << is_field_entry_shift))    != 0; }
352   bool is_long() const                           { return flag_state() == ltos; }
353   bool is_double() const                         { return flag_state() == dtos; }
354   TosState flag_state() const                    { assert((uint)number_of_states <= (uint)tos_state_mask+1, "");
355                                                    return (TosState)((_flags >> tos_state_shift) & tos_state_mask); }
356   void set_indy_resolution_failed();
357 
358   // Code generation support
359   static WordSize size()                         {
360     return in_WordSize(align_up((int)sizeof(ConstantPoolCacheEntry), wordSize) / wordSize);
361   }
362   static ByteSize size_in_bytes()                { return in_ByteSize(sizeof(ConstantPoolCacheEntry)); }
363   static ByteSize indices_offset()               { return byte_offset_of(ConstantPoolCacheEntry, _indices); }
364   static ByteSize f1_offset()                    { return byte_offset_of(ConstantPoolCacheEntry, _f1); }
365   static ByteSize f2_offset()                    { return byte_offset_of(ConstantPoolCacheEntry, _f2); }
366   static ByteSize flags_offset()                 { return byte_offset_of(ConstantPoolCacheEntry, _flags); }
367 
368 #if INCLUDE_JVMTI
369   // RedefineClasses() API support:
370   // If this ConstantPoolCacheEntry refers to old_method then update it
371   // to refer to new_method.
372   // trace_name_printed is set to true if the current call has
373   // printed the klass name so that other routines in the adjust_*
374   // group don't print the klass name.
375   void adjust_method_entry(Method* old_method, Method* new_method,
376          bool* trace_name_printed);
377   bool check_no_old_or_obsolete_entries();
378   Method* get_interesting_method_entry();
379 #endif // INCLUDE_JVMTI
380 
381   // Debugging & Printing
382   void print (outputStream* st, int index) const;
383   void verify(outputStream* st) const;
384 
385   static void verify_tos_state_shift() {
386     // When shifting flags as a 32-bit int, make sure we don't need an extra mask for tos_state:
387     assert((((u4)-1 >> tos_state_shift) & ~tos_state_mask) == 0, "no need for tos_state mask");
388   }
389 
390   void verify_just_initialized(bool f2_used);
391   void reinitialize(bool f2_used);
392 };
393 
394 
395 // A constant pool cache is a runtime data structure set aside to a constant pool. The cache
396 // holds interpreter runtime information for all field access and invoke bytecodes. The cache
397 // is created and initialized before a class is actively used (i.e., initialized), the indivi-
398 // dual cache entries are filled at resolution (i.e., "link") time (see also: rewriter.*).
399 
400 class ConstantPoolCache: public MetaspaceObj {
401   friend class VMStructs;
402   friend class MetadataFactory;
403  private:
404   // If you add a new field that points to any metaspace object, you
405   // must add this field to ConstantPoolCache::metaspace_pointers_do().
406   int             _length;
407   ConstantPool*   _constant_pool;          // the corresponding constant pool
408 
409   // The following fields need to be modified at runtime, so they cannot be
410   // stored in the ConstantPool, which is read-only.
411   // Array of resolved objects from the constant pool and map from resolved
412   // object index to original constant pool index
413   OopHandle            _resolved_references;
414   Array<u2>*           _reference_map;
415 
416   // RedefineClasses support
417   uint64_t             _marking_cycle;
418 
419   // The narrowOop pointer to the archived resolved_references. Set at CDS dump
420   // time when caching java heap object is supported.
421   CDS_JAVA_HEAP_ONLY(int _archived_references_index;)
422 
423   // Sizing
424   debug_only(friend class ClassVerifier;)
425 
426   // Constructor
427   ConstantPoolCache(int length,
428                     const intStack& inverse_index_map,
429                     const intStack& invokedynamic_inverse_index_map,
430                     const intStack& invokedynamic_references_map);
431 
432   // Initialization
433   void initialize(const intArray& inverse_index_map,
434                   const intArray& invokedynamic_inverse_index_map,
435                   const intArray& invokedynamic_references_map);
436  public:
437   static ConstantPoolCache* allocate(ClassLoaderData* loader_data,
438                                      const intStack& cp_cache_map,
439                                      const intStack& invokedynamic_cp_cache_map,
440                                      const intStack& invokedynamic_references_map, TRAPS);
441 
442   int length() const                      { return _length; }
443   void metaspace_pointers_do(MetaspaceClosure* it);
444   MetaspaceObj::Type type() const         { return ConstantPoolCacheType; }
445 
446   oop  archived_references() NOT_CDS_JAVA_HEAP_RETURN_(NULL);
447   void set_archived_references(oop o) NOT_CDS_JAVA_HEAP_RETURN;
448   void clear_archived_references() NOT_CDS_JAVA_HEAP_RETURN;
449 
450   inline oop resolved_references();
451   void set_resolved_references(OopHandle s) { _resolved_references = s; }
452   Array<u2>* reference_map() const        { return _reference_map; }
453   void set_reference_map(Array<u2>* o)    { _reference_map = o; }
454 
455   // Assembly code support
456   static int resolved_references_offset_in_bytes() { return offset_of(ConstantPoolCache, _resolved_references); }
457 
458   // CDS support
459   void remove_unshareable_info();
460   void verify_just_initialized();
461  private:
462   void walk_entries_for_initialization(bool check_only);
463   void set_length(int length)                    { _length = length; }
464 
465   static int header_size()                       { return sizeof(ConstantPoolCache) / wordSize; }
466   static int size(int length)                    { return align_metadata_size(header_size() + length * in_words(ConstantPoolCacheEntry::size())); }
467  public:
468   int size() const                               { return size(length()); }
469  private:
470 
471   // Helpers
472   ConstantPool**        constant_pool_addr()     { return &_constant_pool; }
473   ConstantPoolCacheEntry* base() const           { return (ConstantPoolCacheEntry*)((address)this + in_bytes(base_offset())); }
474 
475   friend class constantPoolCacheKlass;
476   friend class ConstantPoolCacheEntry;
477 
478  public:
479   // Accessors
480   void set_constant_pool(ConstantPool* pool)   { _constant_pool = pool; }
481   ConstantPool* constant_pool() const          { return _constant_pool; }
482   // Fetches the entry at the given index.
483   // In either case the index must not be encoded or byte-swapped in any way.
484   ConstantPoolCacheEntry* entry_at(int i) const {
485     assert(0 <= i && i < length(), "index out of bounds");
486     return base() + i;
487   }
488 
489   // Code generation
490   static ByteSize base_offset()                  { return in_ByteSize(sizeof(ConstantPoolCache)); }
491   static ByteSize entry_offset(int raw_index) {
492     int index = raw_index;
493     return (base_offset() + ConstantPoolCacheEntry::size_in_bytes() * index);
494   }
495 
496 #if INCLUDE_JVMTI
497   // RedefineClasses() API support:
498   // If any entry of this ConstantPoolCache points to any of
499   // old_methods, replace it with the corresponding new_method.
500   // trace_name_printed is set to true if the current call has
501   // printed the klass name so that other routines in the adjust_*
502   // group don't print the klass name.
503   void adjust_method_entries(bool* trace_name_printed);
504   bool check_no_old_or_obsolete_entries();
505   void dump_cache();
506 #endif // INCLUDE_JVMTI
507 
508   // RedefineClasses support
509   DEBUG_ONLY(bool on_stack() { return false; })
510   void deallocate_contents(ClassLoaderData* data);
511   bool is_klass() const { return false; }
512   void record_marking_cycle();
513   uint64_t marking_cycle() { return _marking_cycle; }
514 
515   // Printing
516   void print_on(outputStream* st) const;
517   void print_value_on(outputStream* st) const;
518 
519   const char* internal_name() const { return "{constant pool cache}"; }
520 
521   // Verify
522   void verify_on(outputStream* st);
523 };
524 
525 #endif // SHARE_OOPS_CPCACHE_HPP