1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  24 
  25 #ifndef SHARE_CI_CIOBJECT_HPP
  26 #define SHARE_CI_CIOBJECT_HPP
  27 
  28 #include "ci/ciBaseObject.hpp"
  29 #include "ci/ciClassList.hpp"
  30 #include "runtime/handles.hpp"
  31 #include "runtime/jniHandles.hpp"
  32 
  33 // ciObject
  34 //
  35 // This class represents an oop in the HotSpot virtual machine.
  36 // Its subclasses are structured in a hierarchy which mirrors
  37 // an aggregate of the VM's oop and klass hierarchies (see
  38 // oopHierarchy.hpp).  Each instance of ciObject holds a handle
  39 // to a corresponding oop on the VM side and provides routines
  40 // for accessing the information in its oop.  By using the ciObject
  41 // hierarchy for accessing oops in the VM, the compiler ensures
  42 // that it is safe with respect to garbage collection; that is,
  43 // GC and compilation can proceed independently without
  44 // interference.
  45 //
  46 // Within the VM, the oop and klass hierarchies are separate.
  47 // The compiler interface does not preserve this separation --
  48 // the distinction between `Klass*' and `Klass' are not
  49 // reflected in the interface and instead the Klass hierarchy
  50 // is directly modeled as the subclasses of ciKlass.
  51 class ciObject : public ciBaseObject {
  52   CI_PACKAGE_ACCESS
  53   friend class ciEnv;
  54 
  55 private:
  56   // A JNI handle referring to an oop in the VM.  This
  57   // handle may, in a small set of cases, correctly be NULL.
  58   jobject  _handle;
  59   ciKlass* _klass;
  60 
  61 protected:
  62   ciObject();
  63   ciObject(oop o);
  64   ciObject(Handle h);
  65   ciObject(ciKlass* klass);
  66 
  67   jobject      handle()  const { return _handle; }
  68   // Get the VM oop that this object holds.
  69   oop get_oop() const;
  70 
  71   // Virtual behavior of the print() method.
  72   virtual void print_impl(outputStream* st) {}
  73 
  74   virtual const char* type_string() { return "ciObject"; }
  75 
  76 public:
  77   // The klass of this ciObject.
  78   ciKlass* klass();
  79 
  80   // Are two ciObjects equal?
  81   bool equals(ciObject* obj);
  82 
  83   // A hash value for the convenience of compilers.
  84   int hash();
  85 
  86   // Tells if this oop should be made a constant.
  87   bool should_be_constant();
  88 
  89   // The address which the compiler should embed into the
  90   // generated code to represent this oop.  This address
  91   // is not the true address of the oop -- it will get patched
  92   // during nmethod creation.
  93   //
  94   // Usage note: no address arithmetic allowed.  Oop must
  95   // be registered with the oopRecorder.
  96   jobject constant_encoding();
  97 
  98   virtual bool is_object() const            { return true; }
  99 
 100   // What kind of ciObject is this?
 101   virtual bool is_null_object()       const { return false; }
 102   virtual bool is_call_site()         const { return false; }
 103   virtual bool is_instance()                { return false; }
 104   virtual bool is_member_name()       const { return false; }
 105   virtual bool is_method_handle()     const { return false; }
 106   virtual bool is_method_type()       const { return false; }
 107   virtual bool is_array()                   { return false; }
 108   virtual bool is_obj_array()               { return false; }
 109   virtual bool is_type_array()              { return false; }
 110 
 111   // Is this a type or value which has no associated class?
 112   // It is true of primitive types and null objects.
 113   virtual bool is_classless() const         { return false; }
 114   virtual void dump_replay_data(outputStream* st) { /* do nothing */ }
 115 
 116   // Note: some ciObjects refer to oops which have yet to be created.
 117   // We refer to these as "unloaded".  Specifically, there are
 118   // unloaded instances of java.lang.Class,
 119   // java.lang.invoke.MethodHandle, and java.lang.invoke.MethodType.
 120   // By convention the ciNullObject is considered loaded, and
 121   // primitive types are considered loaded.
 122   bool is_loaded() const {
 123     return handle() != NULL || is_classless();
 124   }
 125 
 126   // Subclass casting with assertions.
 127   ciNullObject* as_null_object() {
 128     assert(is_null_object(), "bad cast");
 129     return (ciNullObject*)this;
 130   }
 131   ciCallSite* as_call_site() {
 132     assert(is_call_site(), "bad cast");
 133     return (ciCallSite*)this;
 134   }
 135   ciInstance* as_instance() {
 136     assert(is_instance(), "bad cast");
 137     return (ciInstance*)this;
 138   }
 139   ciMemberName* as_member_name() {
 140     assert(is_member_name(), "bad cast");
 141     return (ciMemberName*)this;
 142   }
 143   ciMethodHandle* as_method_handle() {
 144     assert(is_method_handle(), "bad cast");
 145     return (ciMethodHandle*)this;
 146   }
 147   ciMethodType* as_method_type() {
 148     assert(is_method_type(), "bad cast");
 149     return (ciMethodType*)this;
 150   }
 151   ciArray* as_array() {
 152     assert(is_array(), "bad cast");
 153     return (ciArray*)this;
 154   }
 155   ciObjArray* as_obj_array() {
 156     assert(is_obj_array(), "bad cast");
 157     return (ciObjArray*)this;
 158   }
 159   ciTypeArray* as_type_array() {
 160     assert(is_type_array(), "bad cast");
 161     return (ciTypeArray*)this;
 162   }
 163 
 164   // Print debugging output about this ciObject.
 165   void print(outputStream* st);
 166   void print() { print(tty); }  // GDB cannot handle default arguments
 167 
 168   // Print debugging output about the oop this ciObject represents.
 169   void print_oop(outputStream* st = tty);
 170 };
 171 
 172 #endif // SHARE_CI_CIOBJECT_HPP