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hotspot/src/share/vm/ci/ciObject.hpp

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+/*
+ * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// ciObject
+//
+// This class represents an oop in the HotSpot virtual machine.
+// Its subclasses are structured in a hierarchy which mirrors
+// an aggregate of the VM's oop and klass hierarchies (see
+// oopHierarchy.hpp).  Each instance of ciObject holds a handle
+// to a corresponding oop on the VM side and provides routines
+// for accessing the information in its oop.  By using the ciObject
+// hierarchy for accessing oops in the VM, the compiler ensures
+// that it is safe with respect to garbage collection; that is,
+// GC and compilation can proceed independently without
+// interference.
+//
+// Within the VM, the oop and klass hierarchies are separate.
+// The compiler interface does not preserve this separation --
+// the distinction between `klassOop' and `Klass' are not
+// reflected in the interface and instead the Klass hierarchy
+// is directly modeled as the subclasses of ciKlass.
+class ciObject : public ResourceObj {
+  CI_PACKAGE_ACCESS
+  friend class ciEnv;
+
+private:
+  // A JNI handle referring to an oop in the VM.  This
+  // handle may, in a small set of cases, correctly be NULL.
+  jobject  _handle;
+  ciKlass* _klass;
+  uint     _ident;
+
+  enum { FLAG_BITS   = 1};
+  enum {
+         PERM_FLAG    = 1
+       };
+protected:
+  ciObject();
+  ciObject(oop o);
+  ciObject(Handle h);
+  ciObject(ciKlass* klass);
+
+  jobject      handle()  const { return _handle; }
+  // Get the VM oop that this object holds.
+  oop get_oop() const {
+    assert(_handle != NULL, "null oop");
+    return JNIHandles::resolve_non_null(_handle);
+  }
+
+  void set_perm() {
+    _ident |=  PERM_FLAG;
+  }
+
+  // Virtual behavior of the print() method.
+  virtual void print_impl(outputStream* st) {}
+
+  virtual const char* type_string() { return "ciObject"; }
+
+  void set_ident(uint id);
+public:
+  // The klass of this ciObject.
+  ciKlass* klass();
+
+  // A number unique to this object.
+  uint ident();
+
+  // Are two ciObjects equal?
+  bool equals(ciObject* obj);
+
+  // A hash value for the convenience of compilers.
+  int hash();
+
+  // Tells if this oop has an encoding.  (I.e., is it null or perm?)
+  // If it does not have an encoding, the compiler is responsible for
+  // making other arrangements for dealing with the oop.
+  // See ciEnv::make_perm_array
+  bool has_encoding();
+
+  // Is this object guaranteed to be in the permanent part of the heap?
+  // If so, CollectedHeap::can_elide_permanent_oop_store_barriers is relevant.
+  // If the answer is false, no guarantees are made.
+  bool is_perm() { return (_ident & PERM_FLAG) != 0; }
+
+  // The address which the compiler should embed into the
+  // generated code to represent this oop.  This address
+  // is not the true address of the oop -- it will get patched
+  // during nmethod creation.
+  //
+  // Usage note: no address arithmetic allowed.  Oop must
+  // be registered with the oopRecorder.
+  jobject encoding();
+
+  // What kind of ciObject is this?
+  virtual bool is_null_object() const       { return false; }
+  virtual bool is_instance()                { return false; }
+  virtual bool is_method()                  { return false; }
+  virtual bool is_method_data()             { return false; }
+  virtual bool is_array()                   { return false; }
+  virtual bool is_obj_array()               { return false; }
+  virtual bool is_type_array()              { return false; }
+  virtual bool is_symbol()                  { return false; }
+  virtual bool is_type()                    { return false; }
+  virtual bool is_return_address()          { return false; }
+  virtual bool is_klass()                   { return false; }
+  virtual bool is_instance_klass()          { return false; }
+  virtual bool is_method_klass()            { return false; }
+  virtual bool is_array_klass()             { return false; }
+  virtual bool is_obj_array_klass()         { return false; }
+  virtual bool is_type_array_klass()        { return false; }
+  virtual bool is_symbol_klass()            { return false; }
+  virtual bool is_klass_klass()             { return false; }
+  virtual bool is_instance_klass_klass()    { return false; }
+  virtual bool is_array_klass_klass()       { return false; }
+  virtual bool is_obj_array_klass_klass()   { return false; }
+  virtual bool is_type_array_klass_klass()  { return false; }
+
+  // Is this a type or value which has no associated class?
+  // It is true of primitive types and null objects.
+  virtual bool is_classless() const         { return false; }
+
+  // Is this ciObject a Java Language Object?  That is,
+  // is the ciObject an instance or an array
+  virtual bool is_java_object()             { return false; }
+
+  // Does this ciObject represent a Java Language class?
+  // That is, is the ciObject an instanceKlass or arrayKlass?
+  virtual bool is_java_klass()              { return false; }
+
+  // Is this ciObject the ciInstanceKlass representing
+  // java.lang.Object()?
+  virtual bool is_java_lang_Object()        { return false; }
+
+  // Does this ciObject refer to a real oop in the VM?
+  //
+  // Note: some ciObjects refer to oops which have yet to be
+  // created.  We refer to these as "unloaded".  Specifically,
+  // there are unloaded ciMethods, ciObjArrayKlasses, and
+  // ciInstanceKlasses.  By convention the ciNullObject is
+  // considered loaded, and primitive types are considered loaded.
+  bool is_loaded() const {
+    return handle() != NULL || is_classless();
+  }
+
+  // Subclass casting with assertions.
+  ciNullObject*            as_null_object() {
+    assert(is_null_object(), "bad cast");
+    return (ciNullObject*)this;
+  }
+  ciInstance*              as_instance() {
+    assert(is_instance(), "bad cast");
+    return (ciInstance*)this;
+  }
+  ciMethod*                as_method() {
+    assert(is_method(), "bad cast");
+    return (ciMethod*)this;
+  }
+  ciMethodData*            as_method_data() {
+    assert(is_method_data(), "bad cast");
+    return (ciMethodData*)this;
+  }
+  ciArray*                 as_array() {
+    assert(is_array(), "bad cast");
+    return (ciArray*)this;
+  }
+  ciObjArray*              as_obj_array() {
+    assert(is_obj_array(), "bad cast");
+    return (ciObjArray*)this;
+  }
+  ciTypeArray*             as_type_array() {
+    assert(is_type_array(), "bad cast");
+    return (ciTypeArray*)this;
+  }
+  ciSymbol*                as_symbol() {
+    assert(is_symbol(), "bad cast");
+    return (ciSymbol*)this;
+  }
+  ciType*                  as_type() {
+    assert(is_type(), "bad cast");
+    return (ciType*)this;
+  }
+  ciReturnAddress*         as_return_address() {
+    assert(is_return_address(), "bad cast");
+    return (ciReturnAddress*)this;
+  }
+  ciKlass*                 as_klass() {
+    assert(is_klass(), "bad cast");
+    return (ciKlass*)this;
+  }
+  ciInstanceKlass*         as_instance_klass() {
+    assert(is_instance_klass(), "bad cast");
+    return (ciInstanceKlass*)this;
+  }
+  ciMethodKlass*           as_method_klass() {
+    assert(is_method_klass(), "bad cast");
+    return (ciMethodKlass*)this;
+  }
+  ciArrayKlass*            as_array_klass() {
+    assert(is_array_klass(), "bad cast");
+    return (ciArrayKlass*)this;
+  }
+  ciObjArrayKlass*         as_obj_array_klass() {
+    assert(is_obj_array_klass(), "bad cast");
+    return (ciObjArrayKlass*)this;
+  }
+  ciTypeArrayKlass*        as_type_array_klass() {
+    assert(is_type_array_klass(), "bad cast");
+    return (ciTypeArrayKlass*)this;
+  }
+  ciSymbolKlass*           as_symbol_klass() {
+    assert(is_symbol_klass(), "bad cast");
+    return (ciSymbolKlass*)this;
+  }
+  ciKlassKlass*            as_klass_klass() {
+    assert(is_klass_klass(), "bad cast");
+    return (ciKlassKlass*)this;
+  }
+  ciInstanceKlassKlass*    as_instance_klass_klass() {
+    assert(is_instance_klass_klass(), "bad cast");
+    return (ciInstanceKlassKlass*)this;
+  }
+  ciArrayKlassKlass*       as_array_klass_klass() {
+    assert(is_array_klass_klass(), "bad cast");
+    return (ciArrayKlassKlass*)this;
+  }
+  ciObjArrayKlassKlass*    as_obj_array_klass_klass() {
+    assert(is_obj_array_klass_klass(), "bad cast");
+    return (ciObjArrayKlassKlass*)this;
+  }
+  ciTypeArrayKlassKlass*   as_type_array_klass_klass() {
+    assert(is_type_array_klass_klass(), "bad cast");
+    return (ciTypeArrayKlassKlass*)this;
+  }
+
+  // Print debugging output about this ciObject.
+  void print(outputStream* st = tty);
+
+  // Print debugging output about the oop this ciObject represents.
+  void print_oop(outputStream* st = tty);
+};