ciObject.hpp revision 1472:c18cbe5936b8 
1/*
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12 * version 2 for more details (a copy is included in the LICENSE file that
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24
25// ciObject
26//
27// This class represents an oop in the HotSpot virtual machine.
28// Its subclasses are structured in a hierarchy which mirrors
29// an aggregate of the VM's oop and klass hierarchies (see
30// oopHierarchy.hpp).  Each instance of ciObject holds a handle
31// to a corresponding oop on the VM side and provides routines
32// for accessing the information in its oop.  By using the ciObject
33// hierarchy for accessing oops in the VM, the compiler ensures
34// that it is safe with respect to garbage collection; that is,
35// GC and compilation can proceed independently without
36// interference.
37//
38// Within the VM, the oop and klass hierarchies are separate.
39// The compiler interface does not preserve this separation --
40// the distinction between `klassOop' and `Klass' are not
41// reflected in the interface and instead the Klass hierarchy
42// is directly modeled as the subclasses of ciKlass.
43class ciObject : public ResourceObj {
44  CI_PACKAGE_ACCESS
45  friend class ciEnv;
46
47private:
48  // A JNI handle referring to an oop in the VM.  This
49  // handle may, in a small set of cases, correctly be NULL.
50  jobject  _handle;
51  ciKlass* _klass;
52  uint     _ident;
53
54  enum { FLAG_BITS   = 2 };
55  enum {
56         PERM_FLAG        = 1,
57         SCAVENGABLE_FLAG = 2
58       };
59protected:
60  ciObject();
61  ciObject(oop o);
62  ciObject(Handle h);
63  ciObject(ciKlass* klass);
64
65  jobject      handle()  const { return _handle; }
66  // Get the VM oop that this object holds.
67  oop get_oop() const {
68    assert(_handle != NULL, "null oop");
69    return JNIHandles::resolve_non_null(_handle);
70  }
71
72  void init_flags_from(oop x) {
73    int flags = 0;
74    if (x != NULL) {
75      if (x->is_perm())
76        flags |= PERM_FLAG;
77      if (x->is_scavengable())
78        flags |= SCAVENGABLE_FLAG;
79    }
80    _ident |= flags;
81  }
82
83  // Virtual behavior of the print() method.
84  virtual void print_impl(outputStream* st) {}
85
86  virtual const char* type_string() { return "ciObject"; }
87
88  void set_ident(uint id);
89public:
90  // The klass of this ciObject.
91  ciKlass* klass();
92
93  // A number unique to this object.
94  uint ident();
95
96  // Are two ciObjects equal?
97  bool equals(ciObject* obj);
98
99  // A hash value for the convenience of compilers.
100  int hash();
101
102  // Tells if this oop has an encoding as a constant.
103  // True if is_scavengable is false.
104  // Also true if ScavengeRootsInCode is non-zero.
105  // If it does not have an encoding, the compiler is responsible for
106  // making other arrangements for dealing with the oop.
107  // See ciEnv::make_array
108  bool can_be_constant();
109
110  // Tells if this oop should be made a constant.
111  // True if is_scavengable is false or ScavengeRootsInCode > 1.
112  bool should_be_constant();
113
114  // Is this object guaranteed to be in the permanent part of the heap?
115  // If so, CollectedHeap::can_elide_permanent_oop_store_barriers is relevant.
116  // If the answer is false, no guarantees are made.
117  bool is_perm() { return (_ident & PERM_FLAG) != 0; }
118
119  // Might this object possibly move during a scavenge operation?
120  // If the answer is true and ScavengeRootsInCode==0, the oop cannot be embedded in code.
121  bool is_scavengable() { return (_ident & SCAVENGABLE_FLAG) != 0; }
122
123  // The address which the compiler should embed into the
124  // generated code to represent this oop.  This address
125  // is not the true address of the oop -- it will get patched
126  // during nmethod creation.
127  //
128  // Usage note: no address arithmetic allowed.  Oop must
129  // be registered with the oopRecorder.
130  jobject constant_encoding();
131
132  // What kind of ciObject is this?
133  virtual bool is_null_object() const       { return false; }
134  virtual bool is_call_site() const         { return false; }
135  virtual bool is_cpcache() const           { return false; }
136  virtual bool is_instance()                { return false; }
137  virtual bool is_method()                  { return false; }
138  virtual bool is_method_data()             { return false; }
139  virtual bool is_method_handle() const     { return false; }
140  virtual bool is_array()                   { return false; }
141  virtual bool is_obj_array()               { return false; }
142  virtual bool is_type_array()              { return false; }
143  virtual bool is_symbol()                  { return false; }
144  virtual bool is_type()                    { return false; }
145  virtual bool is_return_address()          { return false; }
146  virtual bool is_klass()                   { return false; }
147  virtual bool is_instance_klass()          { return false; }
148  virtual bool is_method_klass()            { return false; }
149  virtual bool is_array_klass()             { return false; }
150  virtual bool is_obj_array_klass()         { return false; }
151  virtual bool is_type_array_klass()        { return false; }
152  virtual bool is_symbol_klass()            { return false; }
153  virtual bool is_klass_klass()             { return false; }
154  virtual bool is_instance_klass_klass()    { return false; }
155  virtual bool is_array_klass_klass()       { return false; }
156  virtual bool is_obj_array_klass_klass()   { return false; }
157  virtual bool is_type_array_klass_klass()  { return false; }
158
159  // Is this a type or value which has no associated class?
160  // It is true of primitive types and null objects.
161  virtual bool is_classless() const         { return false; }
162
163  // Is this ciObject a Java Language Object?  That is,
164  // is the ciObject an instance or an array
165  virtual bool is_java_object()             { return false; }
166
167  // Does this ciObject represent a Java Language class?
168  // That is, is the ciObject an instanceKlass or arrayKlass?
169  virtual bool is_java_klass()              { return false; }
170
171  // Is this ciObject the ciInstanceKlass representing
172  // java.lang.Object()?
173  virtual bool is_java_lang_Object()        { return false; }
174
175  // Does this ciObject refer to a real oop in the VM?
176  //
177  // Note: some ciObjects refer to oops which have yet to be
178  // created.  We refer to these as "unloaded".  Specifically,
179  // there are unloaded ciMethods, ciObjArrayKlasses, and
180  // ciInstanceKlasses.  By convention the ciNullObject is
181  // considered loaded, and primitive types are considered loaded.
182  bool is_loaded() const {
183    return handle() != NULL || is_classless();
184  }
185
186  // Subclass casting with assertions.
187  ciNullObject*            as_null_object() {
188    assert(is_null_object(), "bad cast");
189    return (ciNullObject*)this;
190  }
191  ciCallSite*              as_call_site() {
192    assert(is_call_site(), "bad cast");
193    return (ciCallSite*) this;
194  }
195  ciCPCache*               as_cpcache() {
196    assert(is_cpcache(), "bad cast");
197    return (ciCPCache*) this;
198  }
199  ciInstance*              as_instance() {
200    assert(is_instance(), "bad cast");
201    return (ciInstance*)this;
202  }
203  ciMethod*                as_method() {
204    assert(is_method(), "bad cast");
205    return (ciMethod*)this;
206  }
207  ciMethodData*            as_method_data() {
208    assert(is_method_data(), "bad cast");
209    return (ciMethodData*)this;
210  }
211  ciMethodHandle*          as_method_handle() {
212    assert(is_method_handle(), "bad cast");
213    return (ciMethodHandle*) this;
214  }
215  ciArray*                 as_array() {
216    assert(is_array(), "bad cast");
217    return (ciArray*)this;
218  }
219  ciObjArray*              as_obj_array() {
220    assert(is_obj_array(), "bad cast");
221    return (ciObjArray*)this;
222  }
223  ciTypeArray*             as_type_array() {
224    assert(is_type_array(), "bad cast");
225    return (ciTypeArray*)this;
226  }
227  ciSymbol*                as_symbol() {
228    assert(is_symbol(), "bad cast");
229    return (ciSymbol*)this;
230  }
231  ciType*                  as_type() {
232    assert(is_type(), "bad cast");
233    return (ciType*)this;
234  }
235  ciReturnAddress*         as_return_address() {
236    assert(is_return_address(), "bad cast");
237    return (ciReturnAddress*)this;
238  }
239  ciKlass*                 as_klass() {
240    assert(is_klass(), "bad cast");
241    return (ciKlass*)this;
242  }
243  ciInstanceKlass*         as_instance_klass() {
244    assert(is_instance_klass(), "bad cast");
245    return (ciInstanceKlass*)this;
246  }
247  ciMethodKlass*           as_method_klass() {
248    assert(is_method_klass(), "bad cast");
249    return (ciMethodKlass*)this;
250  }
251  ciArrayKlass*            as_array_klass() {
252    assert(is_array_klass(), "bad cast");
253    return (ciArrayKlass*)this;
254  }
255  ciObjArrayKlass*         as_obj_array_klass() {
256    assert(is_obj_array_klass(), "bad cast");
257    return (ciObjArrayKlass*)this;
258  }
259  ciTypeArrayKlass*        as_type_array_klass() {
260    assert(is_type_array_klass(), "bad cast");
261    return (ciTypeArrayKlass*)this;
262  }
263  ciSymbolKlass*           as_symbol_klass() {
264    assert(is_symbol_klass(), "bad cast");
265    return (ciSymbolKlass*)this;
266  }
267  ciKlassKlass*            as_klass_klass() {
268    assert(is_klass_klass(), "bad cast");
269    return (ciKlassKlass*)this;
270  }
271  ciInstanceKlassKlass*    as_instance_klass_klass() {
272    assert(is_instance_klass_klass(), "bad cast");
273    return (ciInstanceKlassKlass*)this;
274  }
275  ciArrayKlassKlass*       as_array_klass_klass() {
276    assert(is_array_klass_klass(), "bad cast");
277    return (ciArrayKlassKlass*)this;
278  }
279  ciObjArrayKlassKlass*    as_obj_array_klass_klass() {
280    assert(is_obj_array_klass_klass(), "bad cast");
281    return (ciObjArrayKlassKlass*)this;
282  }
283  ciTypeArrayKlassKlass*   as_type_array_klass_klass() {
284    assert(is_type_array_klass_klass(), "bad cast");
285    return (ciTypeArrayKlassKlass*)this;
286  }
287
288  // Print debugging output about this ciObject.
289  void print(outputStream* st = tty);
290
291  // Print debugging output about the oop this ciObject represents.
292  void print_oop(outputStream* st = tty);
293};
294