c1_LIRGenerator.hpp revision 1472:c18cbe5936b8 
1/*
2 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25// The classes responsible for code emission and register allocation
26
27
28class LIRGenerator;
29class LIREmitter;
30class Invoke;
31class SwitchRange;
32class LIRItem;
33
34define_array(LIRItemArray, LIRItem*)
35define_stack(LIRItemList, LIRItemArray)
36
37class SwitchRange: public CompilationResourceObj {
38 private:
39  int _low_key;
40  int _high_key;
41  BlockBegin* _sux;
42 public:
43  SwitchRange(int start_key, BlockBegin* sux): _low_key(start_key), _high_key(start_key), _sux(sux) {}
44  void set_high_key(int key) { _high_key = key; }
45
46  int high_key() const { return _high_key; }
47  int low_key() const { return _low_key; }
48  BlockBegin* sux() const { return _sux; }
49};
50
51define_array(SwitchRangeArray, SwitchRange*)
52define_stack(SwitchRangeList, SwitchRangeArray)
53
54
55class ResolveNode;
56
57define_array(NodeArray, ResolveNode*);
58define_stack(NodeList, NodeArray);
59
60
61// Node objects form a directed graph of LIR_Opr
62// Edges between Nodes represent moves from one Node to its destinations
63class ResolveNode: public CompilationResourceObj {
64 private:
65  LIR_Opr    _operand;       // the source or destinaton
66  NodeList   _destinations;  // for the operand
67  bool       _assigned;      // Value assigned to this Node?
68  bool       _visited;       // Node already visited?
69  bool       _start_node;    // Start node already visited?
70
71 public:
72  ResolveNode(LIR_Opr operand)
73    : _operand(operand)
74    , _assigned(false)
75    , _visited(false)
76    , _start_node(false) {};
77
78  // accessors
79  LIR_Opr operand() const           { return _operand; }
80  int no_of_destinations() const    { return _destinations.length(); }
81  ResolveNode* destination_at(int i)     { return _destinations[i]; }
82  bool assigned() const             { return _assigned; }
83  bool visited() const              { return _visited; }
84  bool start_node() const           { return _start_node; }
85
86  // modifiers
87  void append(ResolveNode* dest)         { _destinations.append(dest); }
88  void set_assigned()               { _assigned = true; }
89  void set_visited()                { _visited = true; }
90  void set_start_node()             { _start_node = true; }
91};
92
93
94// This is shared state to be used by the PhiResolver so the operand
95// arrays don't have to be reallocated for reach resolution.
96class PhiResolverState: public CompilationResourceObj {
97  friend class PhiResolver;
98
99 private:
100  NodeList _virtual_operands; // Nodes where the operand is a virtual register
101  NodeList _other_operands;   // Nodes where the operand is not a virtual register
102  NodeList _vreg_table;       // Mapping from virtual register to Node
103
104 public:
105  PhiResolverState() {}
106
107  void reset(int max_vregs);
108};
109
110
111// class used to move value of phi operand to phi function
112class PhiResolver: public CompilationResourceObj {
113 private:
114  LIRGenerator*     _gen;
115  PhiResolverState& _state; // temporary state cached by LIRGenerator
116
117  ResolveNode*   _loop;
118  LIR_Opr _temp;
119
120  // access to shared state arrays
121  NodeList& virtual_operands() { return _state._virtual_operands; }
122  NodeList& other_operands()   { return _state._other_operands;   }
123  NodeList& vreg_table()       { return _state._vreg_table;       }
124
125  ResolveNode* create_node(LIR_Opr opr, bool source);
126  ResolveNode* source_node(LIR_Opr opr)      { return create_node(opr, true); }
127  ResolveNode* destination_node(LIR_Opr opr) { return create_node(opr, false); }
128
129  void emit_move(LIR_Opr src, LIR_Opr dest);
130  void move_to_temp(LIR_Opr src);
131  void move_temp_to(LIR_Opr dest);
132  void move(ResolveNode* src, ResolveNode* dest);
133
134  LIRGenerator* gen() {
135    return _gen;
136  }
137
138 public:
139  PhiResolver(LIRGenerator* _lir_gen, int max_vregs);
140  ~PhiResolver();
141
142  void move(LIR_Opr src, LIR_Opr dest);
143};
144
145
146// only the classes below belong in the same file
147class LIRGenerator: public InstructionVisitor, public BlockClosure {
148
149 private:
150  Compilation*  _compilation;
151  ciMethod*     _method;    // method that we are compiling
152  PhiResolverState  _resolver_state;
153  BlockBegin*   _block;
154  int           _virtual_register_number;
155  Values        _instruction_for_operand;
156  BitMap2D      _vreg_flags; // flags which can be set on a per-vreg basis
157  LIR_List*     _lir;
158  BarrierSet*   _bs;
159
160  LIRGenerator* gen() {
161    return this;
162  }
163
164#ifdef ASSERT
165  LIR_List* lir(const char * file, int line) const {
166    _lir->set_file_and_line(file, line);
167    return _lir;
168  }
169#endif
170  LIR_List* lir() const {
171    return _lir;
172  }
173
174  // a simple cache of constants used within a block
175  GrowableArray<LIR_Const*>       _constants;
176  LIR_OprList                     _reg_for_constants;
177  Values                          _unpinned_constants;
178
179  friend class PhiResolver;
180
181  // unified bailout support
182  void bailout(const char* msg) const            { compilation()->bailout(msg); }
183  bool bailed_out() const                        { return compilation()->bailed_out(); }
184
185  void block_do_prolog(BlockBegin* block);
186  void block_do_epilog(BlockBegin* block);
187
188  // register allocation
189  LIR_Opr rlock(Value instr);                      // lock a free register
190  LIR_Opr rlock_result(Value instr);
191  LIR_Opr rlock_result(Value instr, BasicType type);
192  LIR_Opr rlock_byte(BasicType type);
193  LIR_Opr rlock_callee_saved(BasicType type);
194
195  // get a constant into a register and get track of what register was used
196  LIR_Opr load_constant(Constant* x);
197  LIR_Opr load_constant(LIR_Const* constant);
198
199  void  set_result(Value x, LIR_Opr opr)           {
200    assert(opr->is_valid(), "must set to valid value");
201    assert(x->operand()->is_illegal(), "operand should never change");
202    assert(!opr->is_register() || opr->is_virtual(), "should never set result to a physical register");
203    x->set_operand(opr);
204    assert(opr == x->operand(), "must be");
205    if (opr->is_virtual()) {
206      _instruction_for_operand.at_put_grow(opr->vreg_number(), x, NULL);
207    }
208  }
209  void  set_no_result(Value x)                     { assert(!x->has_uses(), "can't have use"); x->clear_operand(); }
210
211  friend class LIRItem;
212
213  LIR_Opr round_item(LIR_Opr opr);
214  LIR_Opr force_to_spill(LIR_Opr value, BasicType t);
215
216  void  profile_branch(If* if_instr, If::Condition cond);
217
218  PhiResolverState& resolver_state() { return _resolver_state; }
219
220  void  move_to_phi(PhiResolver* resolver, Value cur_val, Value sux_val);
221  void  move_to_phi(ValueStack* cur_state);
222
223  // code emission
224  void do_ArithmeticOp_Long   (ArithmeticOp*    x);
225  void do_ArithmeticOp_Int    (ArithmeticOp*    x);
226  void do_ArithmeticOp_FPU    (ArithmeticOp*    x);
227
228  // platform dependent
229  LIR_Opr getThreadPointer();
230
231  void do_RegisterFinalizer(Intrinsic* x);
232  void do_getClass(Intrinsic* x);
233  void do_currentThread(Intrinsic* x);
234  void do_MathIntrinsic(Intrinsic* x);
235  void do_ArrayCopy(Intrinsic* x);
236  void do_CompareAndSwap(Intrinsic* x, ValueType* type);
237  void do_AttemptUpdate(Intrinsic* x);
238  void do_NIOCheckIndex(Intrinsic* x);
239  void do_FPIntrinsics(Intrinsic* x);
240
241  void do_UnsafePrefetch(UnsafePrefetch* x, bool is_store);
242
243  LIR_Opr call_runtime(BasicTypeArray* signature, LIRItemList* args, address entry, ValueType* result_type, CodeEmitInfo* info);
244  LIR_Opr call_runtime(BasicTypeArray* signature, LIR_OprList* args, address entry, ValueType* result_type, CodeEmitInfo* info);
245
246  // convenience functions
247  LIR_Opr call_runtime(Value arg1, address entry, ValueType* result_type, CodeEmitInfo* info);
248  LIR_Opr call_runtime(Value arg1, Value arg2, address entry, ValueType* result_type, CodeEmitInfo* info);
249
250  // GC Barriers
251
252  // generic interface
253
254  void pre_barrier(LIR_Opr addr_opr, bool patch,  CodeEmitInfo* info);
255  void post_barrier(LIR_OprDesc* addr, LIR_OprDesc* new_val);
256
257  // specific implementations
258  // pre barriers
259
260  void G1SATBCardTableModRef_pre_barrier(LIR_Opr addr_opr, bool patch,  CodeEmitInfo* info);
261
262  // post barriers
263
264  void G1SATBCardTableModRef_post_barrier(LIR_OprDesc* addr, LIR_OprDesc* new_val);
265  void CardTableModRef_post_barrier(LIR_OprDesc* addr, LIR_OprDesc* new_val);
266
267
268  static LIR_Opr result_register_for(ValueType* type, bool callee = false);
269
270  ciObject* get_jobject_constant(Value value);
271
272  LIRItemList* invoke_visit_arguments(Invoke* x);
273  void invoke_load_arguments(Invoke* x, LIRItemList* args, const LIR_OprList* arg_list);
274
275  void trace_block_entry(BlockBegin* block);
276
277  // volatile field operations are never patchable because a klass
278  // must be loaded to know it's volatile which means that the offset
279  // it always known as well.
280  void volatile_field_store(LIR_Opr value, LIR_Address* address, CodeEmitInfo* info);
281  void volatile_field_load(LIR_Address* address, LIR_Opr result, CodeEmitInfo* info);
282
283  void put_Object_unsafe(LIR_Opr src, LIR_Opr offset, LIR_Opr data, BasicType type, bool is_volatile);
284  void get_Object_unsafe(LIR_Opr dest, LIR_Opr src, LIR_Opr offset, BasicType type, bool is_volatile);
285
286  void arithmetic_call_op (Bytecodes::Code code, LIR_Opr result, LIR_OprList* args);
287
288  void increment_counter(address counter, int step = 1);
289  void increment_counter(LIR_Address* addr, int step = 1);
290
291  // increment a counter returning the incremented value
292  LIR_Opr increment_and_return_counter(LIR_Opr base, int offset, int increment);
293
294  // is_strictfp is only needed for mul and div (and only generates different code on i486)
295  void arithmetic_op(Bytecodes::Code code, LIR_Opr result, LIR_Opr left, LIR_Opr right, bool is_strictfp, LIR_Opr tmp, CodeEmitInfo* info = NULL);
296  // machine dependent.  returns true if it emitted code for the multiply
297  bool strength_reduce_multiply(LIR_Opr left, int constant, LIR_Opr result, LIR_Opr tmp);
298
299  void store_stack_parameter (LIR_Opr opr, ByteSize offset_from_sp_in_bytes);
300
301  void jobject2reg_with_patching(LIR_Opr r, ciObject* obj, CodeEmitInfo* info);
302
303  // this loads the length and compares against the index
304  void array_range_check          (LIR_Opr array, LIR_Opr index, CodeEmitInfo* null_check_info, CodeEmitInfo* range_check_info);
305  // For java.nio.Buffer.checkIndex
306  void nio_range_check            (LIR_Opr buffer, LIR_Opr index, LIR_Opr result, CodeEmitInfo* info);
307
308  void arithmetic_op_int  (Bytecodes::Code code, LIR_Opr result, LIR_Opr left, LIR_Opr right, LIR_Opr tmp);
309  void arithmetic_op_long (Bytecodes::Code code, LIR_Opr result, LIR_Opr left, LIR_Opr right, CodeEmitInfo* info = NULL);
310  void arithmetic_op_fpu  (Bytecodes::Code code, LIR_Opr result, LIR_Opr left, LIR_Opr right, bool is_strictfp, LIR_Opr tmp = LIR_OprFact::illegalOpr);
311
312  void shift_op   (Bytecodes::Code code, LIR_Opr dst_reg, LIR_Opr value, LIR_Opr count, LIR_Opr tmp);
313
314  void logic_op   (Bytecodes::Code code, LIR_Opr dst_reg, LIR_Opr left, LIR_Opr right);
315
316  void monitor_enter (LIR_Opr object, LIR_Opr lock, LIR_Opr hdr, LIR_Opr scratch, int monitor_no, CodeEmitInfo* info_for_exception, CodeEmitInfo* info);
317  void monitor_exit  (LIR_Opr object, LIR_Opr lock, LIR_Opr hdr, int monitor_no);
318
319  void new_instance    (LIR_Opr  dst, ciInstanceKlass* klass, LIR_Opr  scratch1, LIR_Opr  scratch2, LIR_Opr  scratch3,  LIR_Opr scratch4, LIR_Opr  klass_reg, CodeEmitInfo* info);
320
321  // machine dependent
322  void cmp_mem_int(LIR_Condition condition, LIR_Opr base, int disp, int c, CodeEmitInfo* info);
323  void cmp_reg_mem(LIR_Condition condition, LIR_Opr reg, LIR_Opr base, int disp, BasicType type, CodeEmitInfo* info);
324  void cmp_reg_mem(LIR_Condition condition, LIR_Opr reg, LIR_Opr base, LIR_Opr disp, BasicType type, CodeEmitInfo* info);
325
326  void arraycopy_helper(Intrinsic* x, int* flags, ciArrayKlass** expected_type);
327
328  // returns a LIR_Address to address an array location.  May also
329  // emit some code as part of address calculation.  If
330  // needs_card_mark is true then compute the full address for use by
331  // both the store and the card mark.
332  LIR_Address* generate_address(LIR_Opr base,
333                                LIR_Opr index, int shift,
334                                int disp,
335                                BasicType type);
336  LIR_Address* generate_address(LIR_Opr base, int disp, BasicType type) {
337    return generate_address(base, LIR_OprFact::illegalOpr, 0, disp, type);
338  }
339  LIR_Address* emit_array_address(LIR_Opr array_opr, LIR_Opr index_opr, BasicType type, bool needs_card_mark);
340
341  // machine preferences and characteristics
342  bool can_inline_as_constant(Value i) const;
343  bool can_inline_as_constant(LIR_Const* c) const;
344  bool can_store_as_constant(Value i, BasicType type) const;
345
346  LIR_Opr safepoint_poll_register();
347  void increment_invocation_counter(CodeEmitInfo* info, bool backedge = false);
348  void increment_backedge_counter(CodeEmitInfo* info) {
349    increment_invocation_counter(info, true);
350  }
351
352  CodeEmitInfo* state_for(Instruction* x, ValueStack* state, bool ignore_xhandler = false);
353  CodeEmitInfo* state_for(Instruction* x);
354
355  // allocates a virtual register for this instruction if
356  // one isn't already allocated.  Only for Phi and Local.
357  LIR_Opr operand_for_instruction(Instruction *x);
358
359  void set_block(BlockBegin* block)              { _block = block; }
360
361  void block_prolog(BlockBegin* block);
362  void block_epilog(BlockBegin* block);
363
364  void do_root (Instruction* instr);
365  void walk    (Instruction* instr);
366
367  void bind_block_entry(BlockBegin* block);
368  void start_block(BlockBegin* block);
369
370  LIR_Opr new_register(BasicType type);
371  LIR_Opr new_register(Value value)              { return new_register(as_BasicType(value->type())); }
372  LIR_Opr new_register(ValueType* type)          { return new_register(as_BasicType(type)); }
373
374  // returns a register suitable for doing pointer math
375  LIR_Opr new_pointer_register() {
376#ifdef _LP64
377    return new_register(T_LONG);
378#else
379    return new_register(T_INT);
380#endif
381  }
382
383  static LIR_Condition lir_cond(If::Condition cond) {
384    LIR_Condition l;
385    switch (cond) {
386    case If::eql: l = lir_cond_equal;        break;
387    case If::neq: l = lir_cond_notEqual;     break;
388    case If::lss: l = lir_cond_less;         break;
389    case If::leq: l = lir_cond_lessEqual;    break;
390    case If::geq: l = lir_cond_greaterEqual; break;
391    case If::gtr: l = lir_cond_greater;      break;
392    };
393    return l;
394  }
395
396  void init();
397
398  SwitchRangeArray* create_lookup_ranges(TableSwitch* x);
399  SwitchRangeArray* create_lookup_ranges(LookupSwitch* x);
400  void do_SwitchRanges(SwitchRangeArray* x, LIR_Opr value, BlockBegin* default_sux);
401
402 public:
403  Compilation*  compilation() const              { return _compilation; }
404  FrameMap*     frame_map() const                { return _compilation->frame_map(); }
405  ciMethod*     method() const                   { return _method; }
406  BlockBegin*   block() const                    { return _block; }
407  IRScope*      scope() const                    { return block()->scope(); }
408
409  int max_virtual_register_number() const        { return _virtual_register_number; }
410
411  void block_do(BlockBegin* block);
412
413  // Flags that can be set on vregs
414  enum VregFlag {
415      must_start_in_memory = 0  // needs to be assigned a memory location at beginning, but may then be loaded in a register
416    , callee_saved     = 1    // must be in a callee saved register
417    , byte_reg         = 2    // must be in a byte register
418    , num_vreg_flags
419
420  };
421
422  LIRGenerator(Compilation* compilation, ciMethod* method)
423    : _compilation(compilation)
424    , _method(method)
425    , _virtual_register_number(LIR_OprDesc::vreg_base)
426    , _vreg_flags(NULL, 0, num_vreg_flags) {
427    init();
428  }
429
430  // for virtual registers, maps them back to Phi's or Local's
431  Instruction* instruction_for_opr(LIR_Opr opr);
432  Instruction* instruction_for_vreg(int reg_num);
433
434  void set_vreg_flag   (int vreg_num, VregFlag f);
435  bool is_vreg_flag_set(int vreg_num, VregFlag f);
436  void set_vreg_flag   (LIR_Opr opr,  VregFlag f) { set_vreg_flag(opr->vreg_number(), f); }
437  bool is_vreg_flag_set(LIR_Opr opr,  VregFlag f) { return is_vreg_flag_set(opr->vreg_number(), f); }
438
439  // statics
440  static LIR_Opr exceptionOopOpr();
441  static LIR_Opr exceptionPcOpr();
442  static LIR_Opr divInOpr();
443  static LIR_Opr divOutOpr();
444  static LIR_Opr remOutOpr();
445  static LIR_Opr shiftCountOpr();
446  LIR_Opr syncTempOpr();
447
448  // returns a register suitable for saving the thread in a
449  // call_runtime_leaf if one is needed.
450  LIR_Opr getThreadTemp();
451
452  // visitor functionality
453  virtual void do_Phi            (Phi*             x);
454  virtual void do_Local          (Local*           x);
455  virtual void do_Constant       (Constant*        x);
456  virtual void do_LoadField      (LoadField*       x);
457  virtual void do_StoreField     (StoreField*      x);
458  virtual void do_ArrayLength    (ArrayLength*     x);
459  virtual void do_LoadIndexed    (LoadIndexed*     x);
460  virtual void do_StoreIndexed   (StoreIndexed*    x);
461  virtual void do_NegateOp       (NegateOp*        x);
462  virtual void do_ArithmeticOp   (ArithmeticOp*    x);
463  virtual void do_ShiftOp        (ShiftOp*         x);
464  virtual void do_LogicOp        (LogicOp*         x);
465  virtual void do_CompareOp      (CompareOp*       x);
466  virtual void do_IfOp           (IfOp*            x);
467  virtual void do_Convert        (Convert*         x);
468  virtual void do_NullCheck      (NullCheck*       x);
469  virtual void do_Invoke         (Invoke*          x);
470  virtual void do_NewInstance    (NewInstance*     x);
471  virtual void do_NewTypeArray   (NewTypeArray*    x);
472  virtual void do_NewObjectArray (NewObjectArray*  x);
473  virtual void do_NewMultiArray  (NewMultiArray*   x);
474  virtual void do_CheckCast      (CheckCast*       x);
475  virtual void do_InstanceOf     (InstanceOf*      x);
476  virtual void do_MonitorEnter   (MonitorEnter*    x);
477  virtual void do_MonitorExit    (MonitorExit*     x);
478  virtual void do_Intrinsic      (Intrinsic*       x);
479  virtual void do_BlockBegin     (BlockBegin*      x);
480  virtual void do_Goto           (Goto*            x);
481  virtual void do_If             (If*              x);
482  virtual void do_IfInstanceOf   (IfInstanceOf*    x);
483  virtual void do_TableSwitch    (TableSwitch*     x);
484  virtual void do_LookupSwitch   (LookupSwitch*    x);
485  virtual void do_Return         (Return*          x);
486  virtual void do_Throw          (Throw*           x);
487  virtual void do_Base           (Base*            x);
488  virtual void do_OsrEntry       (OsrEntry*        x);
489  virtual void do_ExceptionObject(ExceptionObject* x);
490  virtual void do_RoundFP        (RoundFP*         x);
491  virtual void do_UnsafeGetRaw   (UnsafeGetRaw*    x);
492  virtual void do_UnsafePutRaw   (UnsafePutRaw*    x);
493  virtual void do_UnsafeGetObject(UnsafeGetObject* x);
494  virtual void do_UnsafePutObject(UnsafePutObject* x);
495  virtual void do_UnsafePrefetchRead (UnsafePrefetchRead*  x);
496  virtual void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x);
497  virtual void do_ProfileCall    (ProfileCall*     x);
498  virtual void do_ProfileCounter (ProfileCounter*  x);
499};
500
501
502class LIRItem: public CompilationResourceObj {
503 private:
504  Value         _value;
505  LIRGenerator* _gen;
506  LIR_Opr       _result;
507  bool          _destroys_register;
508  LIR_Opr       _new_result;
509
510  LIRGenerator* gen() const { return _gen; }
511
512 public:
513  LIRItem(Value value, LIRGenerator* gen) {
514    _destroys_register = false;
515    _gen = gen;
516    set_instruction(value);
517  }
518
519  LIRItem(LIRGenerator* gen) {
520    _destroys_register = false;
521    _gen = gen;
522    _result = LIR_OprFact::illegalOpr;
523    set_instruction(NULL);
524  }
525
526  void set_instruction(Value value) {
527    _value = value;
528    _result = LIR_OprFact::illegalOpr;
529    if (_value != NULL) {
530      _gen->walk(_value);
531      _result = _value->operand();
532    }
533    _new_result = LIR_OprFact::illegalOpr;
534  }
535
536  Value value() const          { return _value;          }
537  ValueType* type() const      { return value()->type(); }
538  LIR_Opr result()             {
539    assert(!_destroys_register || (!_result->is_register() || _result->is_virtual()),
540           "shouldn't use set_destroys_register with physical regsiters");
541    if (_destroys_register && _result->is_register()) {
542      if (_new_result->is_illegal()) {
543        _new_result = _gen->new_register(type());
544        gen()->lir()->move(_result, _new_result);
545      }
546      return _new_result;
547    } else {
548      return _result;
549    }
550    return _result;
551  }
552
553  void set_result(LIR_Opr opr);
554
555  void load_item();
556  void load_byte_item();
557  void load_nonconstant();
558  // load any values which can't be expressed as part of a single store instruction
559  void load_for_store(BasicType store_type);
560  void load_item_force(LIR_Opr reg);
561
562  void dont_load_item() {
563    // do nothing
564  }
565
566  void set_destroys_register() {
567    _destroys_register = true;
568  }
569
570  bool is_constant() const { return value()->as_Constant() != NULL; }
571  bool is_stack()          { return result()->is_stack(); }
572  bool is_register()       { return result()->is_register(); }
573
574  ciObject* get_jobject_constant() const;
575  jint      get_jint_constant() const;
576  jlong     get_jlong_constant() const;
577  jfloat    get_jfloat_constant() const;
578  jdouble   get_jdouble_constant() const;
579  jint      get_address_constant() const;
580};
581