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 /*

  * Copyright (c) 1999, 2012, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #ifndef SHARE_VM_CI_CIFIELD_HPP

 #define SHARE_VM_CI_CIFIELD_HPP

 #include "ci/ciClassList.hpp"

 #include "ci/ciConstant.hpp"

 #include "ci/ciFlags.hpp"

 #include "ci/ciInstance.hpp"

 // ciField

 //

 // This class represents the result of a field lookup in the VM.

 // The lookup may not succeed, in which case the information in

 // the ciField will be incomplete.

 class ciField : public ResourceObj {

   CI_PACKAGE_ACCESS

   friend class ciEnv;

   friend class ciInstanceKlass;

   friend class NonStaticFieldFiller;

 private:

   ciFlags          _flags;

   ciInstanceKlass* _holder;

   ciSymbol*        _name;

   ciSymbol*        _signature;

   ciType*          _type;

   int              _offset;

   bool             _is_constant;

   ciInstanceKlass* _known_to_link_with_put;

   ciInstanceKlass* _known_to_link_with_get;

   ciConstant       _constant_value;

   // Used for will_link

   int              _cp_index;

   ciType* compute_type();

   ciType* compute_type_impl();

   ciField(ciInstanceKlass* klass, int index);

   ciField(fieldDescriptor* fd);

   // shared constructor code

   void initialize_from(fieldDescriptor* fd);

 public:

   ciFlags flags() { return _flags; }

   // Of which klass is this field a member?

   //

   // Usage note: the declared holder of a field is the class

   // referenced by name in the bytecodes.  The canonical holder

   // is the most general class which holds the field.  This

   // method returns the canonical holder.  The declared holder

   // can be accessed via a method in ciBytecodeStream.

   //

   // Ex.

   //     class A {

   //       public int f = 7;

   //     }

   //     class B extends A {

   //       public void test() {

   //         System.out.println(f);

   //       }

   //     }

   //

   //   A java compiler is permitted to compile the access to

   //   field f as:

   //

   //     getfield B.f

   //

   //   In that case the declared holder of f would be B and

   //   the canonical holder of f would be A.

   ciInstanceKlass* holder() { return _holder; }

   // Name of this field?

   ciSymbol* name() { return _name; }

   // Signature of this field?

   ciSymbol* signature() { return _signature; }

   // Of what type is this field?

   ciType* type() { return (_type == NULL) ? compute_type() : _type; }

   // How is this field actually stored in memory?

   BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; }

   // How big is this field in memory?

   int size_in_bytes() { return type2aelembytes(layout_type()); }

   // What is the offset of this field?

   int offset() {

     assert(_offset >= 1, "illegal call to offset()");

     return _offset;

   }

   // Same question, explicit units.  (Fields are aligned to the byte level.)

   int offset_in_bytes() {

     return offset();

   }

   // Is this field shared?

   bool is_shared() {

     // non-static fields of shared holders are cached

     return _holder->is_shared() && !is_static();

   }

   // Is this field a constant?

   //

   // Clarification: A field is considered constant if:

   //   1. The field is both static and final

   //   2. The canonical holder of the field has undergone

   //      static initialization.

   //   3. If the field is an object or array, then the oop

   //      in question is allocated in perm space.

   //   4. The field is not one of the special static/final

   //      non-constant fields.  These are java.lang.System.in

   //      and java.lang.System.out.  Abomination.

   //

   // A field is also considered constant if it is marked @Stable

   // and is non-null (or non-zero, if a primitive).

   // For non-static fields, the null/zero check must be

   // arranged by the user, as constant_value().is_null_or_zero().

   bool is_constant() { return _is_constant; }

   // Get the constant value of this field.

   ciConstant constant_value() {

     assert(is_static() && is_constant(), "illegal call to constant_value()");

     return _constant_value;

   }

   // Get the constant value of non-static final field in the given

   // object.

   ciConstant constant_value_of(ciObject* object) {

     assert(!is_static() && is_constant(), "only if field is non-static constant");

     assert(object->is_instance(), "must be instance");

     return object->as_instance()->field_value(this);

   }

   // Check for link time errors.  Accessing a field from a

   // certain class via a certain bytecode may or may not be legal.

   // This call checks to see if an exception may be raised by

   // an access of this field.

   //

   // Usage note: if the same field is accessed multiple times

   // in the same compilation, will_link will need to be checked

   // at each point of access.

   bool will_link(ciInstanceKlass* accessing_klass,

                  Bytecodes::Code bc);

   // Java access flags

   bool is_public      () { return flags().is_public(); }

   bool is_private     () { return flags().is_private(); }

   bool is_protected   () { return flags().is_protected(); }

   bool is_static      () { return flags().is_static(); }

   bool is_final       () { return flags().is_final(); }

   bool is_stable      () { return flags().is_stable(); }

   bool is_volatile    () { return flags().is_volatile(); }

   bool is_transient   () { return flags().is_transient(); }

   bool is_call_site_target() {

     ciInstanceKlass* callsite_klass = CURRENT_ENV->CallSite_klass();

     if (callsite_klass == NULL)

       return false;

     return (holder()->is_subclass_of(callsite_klass) && (name() == ciSymbol::target_name()));

   }

   // Debugging output

   void print();

   void print_name_on(outputStream* st);

 };

 #endif // SHARE_VM_CI_CIFIELD_HPP