1 /*
  2  * Copyright (c) 1997, 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.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
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 24 
 25 #ifndef SHARE_OOPS_GENERATEOOPMAP_HPP
 26 #define SHARE_OOPS_GENERATEOOPMAP_HPP
 27 
 28 #include "interpreter/bytecodeStream.hpp"
 29 #include "memory/allocation.hpp"
 30 #include "oops/method.hpp"
 31 #include "oops/oopsHierarchy.hpp"
 32 #include "runtime/signature.hpp"
 33 #include "utilities/bitMap.hpp"
 34 
 35 // Forward definition
 36 class GenerateOopMap;
 37 class BasicBlock;
 38 class CellTypeState;
 39 class StackMap;
 40 
 41 // These two should be removed. But requires som code to be cleaned up
 42 #define MAXARGSIZE      256      // This should be enough
 43 #define MAX_LOCAL_VARS  65536    // 16-bit entry
 44 
 45 typedef void (*jmpFct_t)(GenerateOopMap *c, int bcpDelta, int* data);
 46 
 47 
 48 //  RetTable
 49 //
 50 // Contains maping between jsr targets and there return addresses. One-to-many mapping
 51 //
 52 class RetTableEntry : public ResourceObj {
 53  private:
 54   static int _init_nof_jsrs;                      // Default size of jsrs list
 55   int _target_bci;                                // Target PC address of jump (bytecode index)
 56   GrowableArray<intptr_t> * _jsrs;                     // List of return addresses  (bytecode index)
 57   RetTableEntry *_next;                           // Link to next entry
 58  public:
 59    RetTableEntry(int target, RetTableEntry *next);
 60 
 61   // Query
 62   int target_bci() const                      { return _target_bci; }
 63   int nof_jsrs() const                        { return _jsrs->length(); }
 64   int jsrs(int i) const                       { assert(i>=0 && i<nof_jsrs(), "Index out of bounds"); return _jsrs->at(i); }
 65 
 66   // Update entry
 67   void add_jsr    (int return_bci)            { _jsrs->append(return_bci); }
 68   void add_delta  (int bci, int delta);
 69   RetTableEntry * next()  const               { return _next; }
 70 };
 71 
 72 
 73 class RetTable {
 74  private:
 75   RetTableEntry *_first;
 76   static int _init_nof_entries;
 77 
 78   void add_jsr(int return_bci, int target_bci);   // Adds entry to list
 79  public:
 80   RetTable()                                                  { _first = NULL; }
 81   void compute_ret_table(const methodHandle& method);
 82   void update_ret_table(int bci, int delta);
 83   RetTableEntry* find_jsrs_for_target(int targBci);
 84 };
 85 
 86 //
 87 // CellTypeState
 88 //
 89 class CellTypeState {
 90  private:
 91   unsigned int _state;
 92 
 93   // Masks for separating the BITS and INFO portions of a CellTypeState
 94   enum { info_mask            = right_n_bits(28),
 95          bits_mask            = (int)(~info_mask) };
 96 
 97   // These constant are used for manipulating the BITS portion of a
 98   // CellTypeState
 99   enum { uninit_bit           = (int)(nth_bit(31)),
100          ref_bit              = nth_bit(30),
101          val_bit              = nth_bit(29),
102          addr_bit             = nth_bit(28),
103          live_bits_mask       = (int)(bits_mask & ~uninit_bit) };
104 
105   // These constants are used for manipulating the INFO portion of a
106   // CellTypeState
107   enum { top_info_bit         = nth_bit(27),
108          not_bottom_info_bit  = nth_bit(26),
109          info_data_mask       = right_n_bits(26),
110          info_conflict        = info_mask };
111 
112   // Within the INFO data, these values are used to distinguish different
113   // kinds of references.
114   enum { ref_not_lock_bit     = nth_bit(25),  // 0 if this reference is locked as a monitor
115          ref_slot_bit         = nth_bit(24),  // 1 if this reference is a "slot" reference,
116                                               // 0 if it is a "line" reference.
117          ref_data_mask        = right_n_bits(24) };
118 
119 
120   // These values are used to initialize commonly used CellTypeState
121   // constants.
122   enum { bottom_value         = 0,
123          uninit_value         = (int)(uninit_bit | info_conflict),
124          ref_value            = ref_bit,
125          ref_conflict         = ref_bit | info_conflict,
126          val_value            = val_bit | info_conflict,
127          addr_value           = addr_bit,
128          addr_conflict        = addr_bit | info_conflict };
129 
130  public:
131 
132   // Since some C++ constructors generate poor code for declarations of the
133   // form...
134   //
135   //   CellTypeState vector[length];
136   //
137   // ...we avoid making a constructor for this class.  CellTypeState values
138   // should be constructed using one of the make_* methods:
139 
140   static CellTypeState make_any(int state) {
141     CellTypeState s;
142     s._state = state;
143     // Causes SS10 warning.
144     // assert(s.is_valid_state(), "check to see if CellTypeState is valid");
145     return s;
146   }
147 
148   static CellTypeState make_bottom() {
149     return make_any(0);
150   }
151 
152   static CellTypeState make_top() {
153     return make_any(AllBits);
154   }
155 
156   static CellTypeState make_addr(int bci) {
157     assert((bci >= 0) && (bci < info_data_mask), "check to see if ret addr is valid");
158     return make_any(addr_bit | not_bottom_info_bit | (bci & info_data_mask));
159   }
160 
161   static CellTypeState make_slot_ref(int slot_num) {
162     assert(slot_num >= 0 && slot_num < ref_data_mask, "slot out of range");
163     return make_any(ref_bit | not_bottom_info_bit | ref_not_lock_bit | ref_slot_bit |
164                     (slot_num & ref_data_mask));
165   }
166 
167   static CellTypeState make_line_ref(int bci) {
168     assert(bci >= 0 && bci < ref_data_mask, "line out of range");
169     return make_any(ref_bit | not_bottom_info_bit | ref_not_lock_bit |
170                     (bci & ref_data_mask));
171   }
172 
173   static CellTypeState make_lock_ref(int bci) {
174     assert(bci >= 0 && bci < ref_data_mask, "line out of range");
175     return make_any(ref_bit | not_bottom_info_bit | (bci & ref_data_mask));
176   }
177 
178   // Query methods:
179   bool is_bottom() const                { return _state == 0; }
180   bool is_live() const                  { return ((_state & live_bits_mask) != 0); }
181   bool is_valid_state() const {
182     // Uninitialized and value cells must contain no data in their info field:
183     if ((can_be_uninit() || can_be_value()) && !is_info_top()) {
184       return false;
185     }
186     // The top bit is only set when all info bits are set:
187     if (is_info_top() && ((_state & info_mask) != info_mask)) {
188       return false;
189     }
190     // The not_bottom_bit must be set when any other info bit is set:
191     if (is_info_bottom() && ((_state & info_mask) != 0)) {
192       return false;
193     }
194     return true;
195   }
196 
197   bool is_address() const               { return ((_state & bits_mask) == addr_bit); }
198   bool is_reference() const             { return ((_state & bits_mask) == ref_bit); }
199   bool is_value() const                 { return ((_state & bits_mask) == val_bit); }
200   bool is_uninit() const                { return ((_state & bits_mask) == (uint)uninit_bit); }
201 
202   bool can_be_address() const           { return ((_state & addr_bit) != 0); }
203   bool can_be_reference() const         { return ((_state & ref_bit) != 0); }
204   bool can_be_value() const             { return ((_state & val_bit) != 0); }
205   bool can_be_uninit() const            { return ((_state & uninit_bit) != 0); }
206 
207   bool is_info_bottom() const           { return ((_state & not_bottom_info_bit) == 0); }
208   bool is_info_top() const              { return ((_state & top_info_bit) != 0); }
209   int  get_info() const {
210     assert((!is_info_top() && !is_info_bottom()),
211            "check to make sure top/bottom info is not used");
212     return (_state & info_data_mask);
213   }
214 
215   bool is_good_address() const          { return is_address() && !is_info_top(); }
216   bool is_lock_reference() const {
217     return ((_state & (bits_mask | top_info_bit | ref_not_lock_bit)) == ref_bit);
218   }
219   bool is_nonlock_reference() const {
220     return ((_state & (bits_mask | top_info_bit | ref_not_lock_bit)) == (ref_bit | ref_not_lock_bit));
221   }
222 
223   bool equal(CellTypeState a) const     { return _state == a._state; }
224   bool equal_kind(CellTypeState a) const {
225     return (_state & bits_mask) == (a._state & bits_mask);
226   }
227 
228   char to_char() const;
229 
230   // Merge
231   CellTypeState merge (CellTypeState cts, int slot) const;
232 
233   // Debugging output
234   void print(outputStream *os);
235 
236   // Default values of common values
237   static CellTypeState bottom;
238   static CellTypeState uninit;
239   static CellTypeState ref;
240   static CellTypeState value;
241   static CellTypeState refUninit;
242   static CellTypeState varUninit;
243   static CellTypeState top;
244   static CellTypeState addr;
245 };
246 
247 
248 //
249 // BasicBlockStruct
250 //
251 class BasicBlock: ResourceObj {
252  private:
253   bool            _changed;                 // Reached a fixpoint or not
254  public:
255   enum Constants {
256     _dead_basic_block = -2,
257     _unreached        = -1                  // Alive but not yet reached by analysis
258     // >=0                                  // Alive and has a merged state
259   };
260 
261   int             _bci;                     // Start of basic block
262   int             _end_bci;                 // Bci of last instruction in basicblock
263   int             _max_locals;              // Determines split between vars and stack
264   int             _max_stack;               // Determines split between stack and monitors
265   CellTypeState*  _state;                   // State (vars, stack) at entry.
266   int             _stack_top;               // -1 indicates bottom stack value.
267   int             _monitor_top;             // -1 indicates bottom monitor stack value.
268 
269   CellTypeState* vars()                     { return _state; }
270   CellTypeState* stack()                    { return _state + _max_locals; }
271 
272   bool changed()                            { return _changed; }
273   void set_changed(bool s)                  { _changed = s; }
274 
275   bool is_reachable() const                 { return _stack_top >= 0; }  // Analysis has reached this basicblock
276 
277   // All basicblocks that are unreachable are going to have a _stack_top == _dead_basic_block.
278   // This info. is setup in a pre-parse before the real abstract interpretation starts.
279   bool is_dead() const                      { return _stack_top == _dead_basic_block; }
280   bool is_alive() const                     { return _stack_top != _dead_basic_block; }
281   void mark_as_alive()                      { assert(is_dead(), "must be dead"); _stack_top = _unreached; }
282 };
283 
284 
285 //
286 //  GenerateOopMap
287 //
288 // Main class used to compute the pointer-maps in a Method
289 //
290 class GenerateOopMap {
291  protected:
292 
293   // _monitor_top is set to this constant to indicate that a monitor matching
294   // problem was encountered prior to this point in control flow.
295   enum { bad_monitors = -1 };
296 
297   // Main variables
298   methodHandle _method;                     // The method we are examine
299   RetTable     _rt;                         // Contains the return address mappings
300   int          _max_locals;                 // Cached value of no. of locals
301   int          _max_stack;                  // Cached value of max. stack depth
302   int          _max_monitors;               // Cached value of max. monitor stack depth
303   int          _has_exceptions;             // True, if exceptions exist for method
304   bool         _got_error;                  // True, if an error occurred during interpretation.
305   Handle       _exception;                  // Exception if got_error is true.
306   bool         _did_rewriting;              // was bytecodes rewritten
307   bool         _did_relocation;             // was relocation neccessary
308   bool         _monitor_safe;               // The monitors in this method have been determined
309                                             // to be safe.
310 
311   // Working Cell type state
312   int            _state_len;                // Size of states
313   CellTypeState *_state;                    // list of states
314   char          *_state_vec_buf;            // Buffer used to print a readable version of a state
315   int            _stack_top;
316   int            _monitor_top;
317 
318   // Timing and statistics
319   static elapsedTimer _total_oopmap_time;   // Holds cumulative oopmap generation time
320   static uint64_t     _total_byte_count;    // Holds cumulative number of bytes inspected
321 
322   // Cell type methods
323   void            init_state();
324   void            make_context_uninitialized ();
325   int             methodsig_to_effect        (Symbol* signature, bool isStatic, CellTypeState* effect);
326   bool            merge_local_state_vectors  (CellTypeState* cts, CellTypeState* bbts);
327   bool            merge_monitor_state_vectors(CellTypeState* cts, CellTypeState* bbts);
328   void            copy_state                 (CellTypeState *dst, CellTypeState *src);
329   void            merge_state_into_bb        (BasicBlock *bb);
330   static void     merge_state                (GenerateOopMap *gom, int bcidelta, int* data);
331   void            set_var                    (int localNo, CellTypeState cts);
332   CellTypeState   get_var                    (int localNo);
333   CellTypeState   pop                        ();
334   void            push                       (CellTypeState cts);
335   CellTypeState   monitor_pop                ();
336   void            monitor_push               (CellTypeState cts);
337   CellTypeState * vars                       ()                                             { return _state; }
338   CellTypeState * stack                      ()                                             { return _state+_max_locals; }
339   CellTypeState * monitors                   ()                                             { return _state+_max_locals+_max_stack; }
340 
341   void            replace_all_CTS_matches    (CellTypeState match,
342                                               CellTypeState replace);
343   void            print_states               (outputStream *os, CellTypeState *vector, int num);
344   void            print_current_state        (outputStream   *os,
345                                               BytecodeStream *itr,
346                                               bool            detailed);
347   void            report_monitor_mismatch    (const char *msg);
348 
349   // Basicblock info
350   BasicBlock *    _basic_blocks;             // Array of basicblock info
351   int             _gc_points;
352   int             _bb_count;
353   ResourceBitMap  _bb_hdr_bits;
354 
355   // Basicblocks methods
356   void          initialize_bb               ();
357   void          mark_bbheaders_and_count_gc_points();
358   bool          is_bb_header                (int bci) const   {
359     return _bb_hdr_bits.at(bci);
360   }
361   int           gc_points                   () const                          { return _gc_points; }
362   int           bb_count                    () const                          { return _bb_count; }
363   void          set_bbmark_bit              (int bci);
364   BasicBlock *  get_basic_block_at          (int bci) const;
365   BasicBlock *  get_basic_block_containing  (int bci) const;
366   void          interp_bb                   (BasicBlock *bb);
367   void          restore_state               (BasicBlock *bb);
368   int           next_bb_start_pc            (BasicBlock *bb);
369   void          update_basic_blocks         (int bci, int delta, int new_method_size);
370   static void   bb_mark_fct                 (GenerateOopMap *c, int deltaBci, int *data);
371 
372   // Dead code detection
373   void          mark_reachable_code();
374   static void   reachable_basicblock        (GenerateOopMap *c, int deltaBci, int *data);
375 
376   // Interpretation methods (primary)
377   void  do_interpretation                   ();
378   void  init_basic_blocks                   ();
379   void  setup_method_entry_state            ();
380   void  interp_all                          ();
381 
382   // Interpretation methods (secondary)
383   void  interp1                             (BytecodeStream *itr);
384   void  do_exception_edge                   (BytecodeStream *itr);
385   void  check_type                          (CellTypeState expected, CellTypeState actual);
386   void  ppstore                             (CellTypeState *in,  int loc_no);
387   void  ppload                              (CellTypeState *out, int loc_no);
388   void  ppush1                              (CellTypeState in);
389   void  ppush                               (CellTypeState *in);
390   void  ppop1                               (CellTypeState out);
391   void  ppop                                (CellTypeState *out);
392   void  ppop_any                            (int poplen);
393   void  pp                                  (CellTypeState *in, CellTypeState *out);
394   void  pp_new_ref                          (CellTypeState *in, int bci);
395   void  ppdupswap                           (int poplen, const char *out);
396   void  do_ldc                              (int bci);
397   void  do_astore                           (int idx);
398   void  do_jsr                              (int delta);
399   void  do_field                            (int is_get, int is_static, int idx, int bci);
400   void  do_method                           (int is_static, int is_interface, int idx, int bci);
401   void  do_multianewarray                   (int dims, int bci);
402   void  do_monitorenter                     (int bci);
403   void  do_monitorexit                      (int bci);
404   void  do_return_monitor_check             ();
405   void  do_checkcast                        ();
406   CellTypeState *signature_to_effect        (const Symbol* sig, int bci, CellTypeState *out);
407   int copy_cts                              (CellTypeState *dst, CellTypeState *src);
408 
409   // Error handling
410   void  error_work                          (const char *format, va_list ap) ATTRIBUTE_PRINTF(2, 0);
411   void  report_error                        (const char *format, ...) ATTRIBUTE_PRINTF(2, 3);
412   void  verify_error                        (const char *format, ...) ATTRIBUTE_PRINTF(2, 3);
413   bool  got_error()                         { return _got_error; }
414 
415   // Create result set
416   bool  _report_result;
417   bool  _report_result_for_send;            // Unfortunatly, stackmaps for sends are special, so we need some extra
418   BytecodeStream *_itr_send;                // variables to handle them properly.
419 
420   void  report_result                       ();
421 
422   // Initvars
423   GrowableArray<intptr_t> * _init_vars;
424 
425   void  initialize_vars                     ();
426   void  add_to_ref_init_set                 (int localNo);
427 
428   // Conflicts rewrite logic
429   bool      _conflict;                      // True, if a conflict occurred during interpretation
430   int       _nof_refval_conflicts;          // No. of conflicts that require rewrites
431   int *     _new_var_map;
432 
433   void record_refval_conflict               (int varNo);
434   void rewrite_refval_conflicts             ();
435   void rewrite_refval_conflict              (int from, int to);
436   bool rewrite_refval_conflict_inst         (BytecodeStream *i, int from, int to);
437   bool rewrite_load_or_store                (BytecodeStream *i, Bytecodes::Code bc, Bytecodes::Code bc0, unsigned int varNo);
438 
439   void expand_current_instr                 (int bci, int ilen, int newIlen, u_char inst_buffer[]);
440   bool is_astore                            (BytecodeStream *itr, int *index);
441   bool is_aload                             (BytecodeStream *itr, int *index);
442 
443   // List of bci's where a return address is on top of the stack
444   GrowableArray<intptr_t> *_ret_adr_tos;
445 
446   bool stack_top_holds_ret_addr             (int bci);
447   void compute_ret_adr_at_TOS               ();
448   void update_ret_adr_at_TOS                (int bci, int delta);
449 
450   int  binsToHold                           (int no)                      { return  ((no+(BitsPerWord-1))/BitsPerWord); }
451   char *state_vec_to_string                 (CellTypeState* vec, int len);
452 
453   // Helper method. Can be used in subclasses to fx. calculate gc_points. If the current instuction
454   // is a control transfer, then calls the jmpFct all possible destinations.
455   void  ret_jump_targets_do                 (BytecodeStream *bcs, jmpFct_t jmpFct, int varNo,int *data);
456   bool  jump_targets_do                     (BytecodeStream *bcs, jmpFct_t jmpFct, int *data);
457 
458   friend class RelocCallback;
459  public:
460   GenerateOopMap(const methodHandle& method);
461 
462   // Compute the map - returns true on success and false on error.
463   bool compute_map(Thread* current);
464   // Returns the exception related to any error, if the map was computed by a suitable JavaThread.
465   Handle exception() { return _exception; }
466 
467   void result_for_basicblock(int bci);    // Do a callback on fill_stackmap_for_opcodes for basicblock containing bci
468 
469   // Query
470   int max_locals() const                           { return _max_locals; }
471   Method* method() const                           { return _method(); }
472   methodHandle method_as_handle() const            { return _method; }
473 
474   bool did_rewriting()                             { return _did_rewriting; }
475   bool did_relocation()                            { return _did_relocation; }
476 
477   static void print_time();
478 
479   // Monitor query
480   bool monitor_safe()                              { return _monitor_safe; }
481 
482   // Specialization methods. Intended use:
483   // - possible_gc_point must return true for every bci for which the stackmaps must be returned
484   // - fill_stackmap_prolog is called just before the result is reported. The arguments tells the estimated
485   //   number of gc points
486   // - fill_stackmap_for_opcodes is called once for each bytecode index in order (0...code_length-1)
487   // - fill_stackmap_epilog is called after all results has been reported. Note: Since the algorithm does not report
488   //   stackmaps for deadcode, fewer gc_points might have been encounted than assumed during the epilog. It is the
489   //   responsibility of the subclass to count the correct number.
490   // - fill_init_vars are called once with the result of the init_vars computation
491   //
492   // All these methods are used during a call to: compute_map. Note: Non of the return results are valid
493   // after compute_map returns, since all values are allocated as resource objects.
494   //
495   // All virtual method must be implemented in subclasses
496   virtual bool allow_rewrites             () const                        { return false; }
497   virtual bool report_results             () const                        { return true;  }
498   virtual bool report_init_vars           () const                        { return true;  }
499   virtual bool possible_gc_point          (BytecodeStream *bcs)           { ShouldNotReachHere(); return false; }
500   virtual void fill_stackmap_prolog       (int nof_gc_points)             { ShouldNotReachHere(); }
501   virtual void fill_stackmap_epilog       ()                              { ShouldNotReachHere(); }
502   virtual void fill_stackmap_for_opcodes  (BytecodeStream *bcs,
503                                            CellTypeState* vars,
504                                            CellTypeState* stack,
505                                            int stackTop)                  { ShouldNotReachHere(); }
506   virtual void fill_init_vars             (GrowableArray<intptr_t> *init_vars) { ShouldNotReachHere();; }
507 };
508 
509 //
510 // Subclass of the GenerateOopMap Class that just do rewrites of the method, if needed.
511 // It does not store any oopmaps.
512 //
513 class ResolveOopMapConflicts: public GenerateOopMap {
514  private:
515 
516   bool _must_clear_locals;
517 
518   virtual bool report_results() const     { return false; }
519   virtual bool report_init_vars() const   { return true;  }
520   virtual bool allow_rewrites() const     { return true;  }
521   virtual bool possible_gc_point          (BytecodeStream *bcs)           { return false; }
522   virtual void fill_stackmap_prolog       (int nof_gc_points)             {}
523   virtual void fill_stackmap_epilog       ()                              {}
524   virtual void fill_stackmap_for_opcodes  (BytecodeStream *bcs,
525                                            CellTypeState* vars,
526                                            CellTypeState* stack,
527                                            int stack_top)                 {}
528   virtual void fill_init_vars             (GrowableArray<intptr_t> *init_vars) { _must_clear_locals = init_vars->length() > 0; }
529 
530 #ifndef PRODUCT
531   // Statistics
532   static int _nof_invocations;
533   static int _nof_rewrites;
534   static int _nof_relocations;
535 #endif
536 
537  public:
538   ResolveOopMapConflicts(const methodHandle& method) : GenerateOopMap(method) { _must_clear_locals = false; };
539 
540   methodHandle do_potential_rewrite(TRAPS);
541   bool must_clear_locals() const { return _must_clear_locals; }
542 };
543 
544 
545 //
546 // Subclass used by the compiler to generate pairing infomation
547 //
548 class GeneratePairingInfo: public GenerateOopMap {
549  private:
550 
551   virtual bool report_results() const     { return false; }
552   virtual bool report_init_vars() const   { return false; }
553   virtual bool allow_rewrites() const     { return false;  }
554   virtual bool possible_gc_point          (BytecodeStream *bcs)           { return false; }
555   virtual void fill_stackmap_prolog       (int nof_gc_points)             {}
556   virtual void fill_stackmap_epilog       ()                              {}
557   virtual void fill_stackmap_for_opcodes  (BytecodeStream *bcs,
558                                            CellTypeState* vars,
559                                            CellTypeState* stack,
560                                            int stack_top)                 {}
561   virtual void fill_init_vars             (GrowableArray<intptr_t> *init_vars) {}
562  public:
563   GeneratePairingInfo(const methodHandle& method) : GenerateOopMap(method)       {};
564 
565   // Call compute_map() to generate info.
566 };
567 
568 #endif // SHARE_OOPS_GENERATEOOPMAP_HPP