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

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+/*
+ * Copyright 1999-2007 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.
+ *
+ */
+
+#include "incls/_precompiled.incl"
+#include "incls/_ciObject.cpp.incl"
+
+// 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.
+
+// ------------------------------------------------------------------
+// ciObject::ciObject
+ciObject::ciObject(oop o) {
+  ASSERT_IN_VM;
+  if (ciObjectFactory::is_initialized()) {
+    _handle = JNIHandles::make_local(o);
+  } else {
+    _handle = JNIHandles::make_global(o);
+  }
+  _klass = NULL;
+  _ident = 0;
+}
+
+// ------------------------------------------------------------------
+// ciObject::ciObject
+//
+ciObject::ciObject(Handle h) {
+  ASSERT_IN_VM;
+  if (ciObjectFactory::is_initialized()) {
+    _handle = JNIHandles::make_local(h());
+  } else {
+    _handle = JNIHandles::make_global(h);
+  }
+  _klass = NULL;
+  _ident = 0;
+}
+
+// ------------------------------------------------------------------
+// ciObject::ciObject
+//
+// Unloaded klass/method variant.  `klass' is the klass of the unloaded
+// klass/method, if that makes sense.
+ciObject::ciObject(ciKlass* klass) {
+  ASSERT_IN_VM;
+  assert(klass != NULL, "must supply klass");
+  _handle = NULL;
+  _klass = klass;
+  _ident = 0;
+}
+
+// ------------------------------------------------------------------
+// ciObject::ciObject
+//
+// NULL variant.  Used only by ciNullObject.
+ciObject::ciObject() {
+  ASSERT_IN_VM;
+  _handle = NULL;
+  _klass = NULL;
+  _ident = 0;
+}
+
+// ------------------------------------------------------------------
+// ciObject::klass
+//
+// Get the ciKlass of this ciObject.
+ciKlass* ciObject::klass() {
+  if (_klass == NULL) {
+    if (_handle == NULL) {
+      // When both _klass and _handle are NULL, we are dealing
+      // with the distinguished instance of ciNullObject.
+      // No one should ask it for its klass.
+      assert(is_null_object(), "must be null object");
+      ShouldNotReachHere();
+      return NULL;
+    }
+
+    GUARDED_VM_ENTRY(
+      oop o = get_oop();
+      _klass = CURRENT_ENV->get_object(o->klass())->as_klass();
+    );
+  }
+  return _klass;
+}
+
+// ------------------------------------------------------------------
+// ciObject::set_ident
+//
+// Set the unique identity number of a ciObject.
+void ciObject::set_ident(uint id) {
+  assert((_ident >> FLAG_BITS) == 0, "must only initialize once");
+  assert( id < ((uint)1 << (BitsPerInt-FLAG_BITS)), "id too big");
+  _ident = _ident + (id << FLAG_BITS);
+}
+
+// ------------------------------------------------------------------
+// ciObject::ident
+//
+// Report the unique identity number of a ciObject.
+uint ciObject::ident() {
+  uint id = _ident >> FLAG_BITS;
+  assert(id != 0, "must be initialized");
+  return id;
+}
+
+// ------------------------------------------------------------------
+// ciObject::equals
+//
+// Are two ciObjects equal?
+bool ciObject::equals(ciObject* obj) {
+  return (this == obj);
+}
+
+// ------------------------------------------------------------------
+// ciObject::hash
+//
+// A hash value for the convenience of compilers.
+//
+// Implementation note: we use the address of the ciObject as the
+// basis for the hash.  Use the _ident field, which is well-behaved.
+int ciObject::hash() {
+  return ident() * 31;
+}
+
+// ------------------------------------------------------------------
+// ciObject::encoding
+//
+// 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.
+//
+//
+//
+// Implementation note: we use the handle as the encoding.  The
+// nmethod constructor resolves the handle and patches in the oop.
+//
+// This method should be changed to return an generified address
+// to discourage use of the JNI handle.
+jobject ciObject::encoding() {
+  assert(is_null_object() || handle() != NULL, "cannot embed null pointer");
+  assert(has_encoding(), "oop must be NULL or perm");
+  return handle();
+}
+
+// ------------------------------------------------------------------
+// ciObject::has_encoding
+bool ciObject::has_encoding() {
+  return handle() == NULL || is_perm();
+}
+
+
+// ------------------------------------------------------------------
+// ciObject::print
+//
+// Print debugging output about this ciObject.
+//
+// Implementation note: dispatch to the virtual print_impl behavior
+// for this ciObject.
+void ciObject::print(outputStream* st) {
+  st->print("<%s", type_string());
+  GUARDED_VM_ENTRY(print_impl(st);)
+  st->print(" ident=%d %s address=0x%x>", ident(),
+        is_perm() ? "PERM" : "",
+        (address)this);
+}
+
+// ------------------------------------------------------------------
+// ciObject::print_oop
+//
+// Print debugging output about the oop this ciObject represents.
+void ciObject::print_oop(outputStream* st) {
+  if (is_null_object()) {
+    st->print_cr("NULL");
+  } else if (!is_loaded()) {
+    st->print_cr("UNLOADED");
+  } else {
+    GUARDED_VM_ENTRY(get_oop()->print_on(st);)
+  }
+}