duke@435: /*
xdono@631:  * Copyright 1999-2008 Sun Microsystems, Inc.  All Rights Reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: // ciField
duke@435: //
duke@435: // This class represents the result of a field lookup in the VM.
duke@435: // The lookup may not succeed, in which case the information in
duke@435: // the ciField will be incomplete.
duke@435: class ciField : public ResourceObj {
duke@435:   CI_PACKAGE_ACCESS
duke@435:   friend class ciEnv;
duke@435:   friend class ciInstanceKlass;
duke@435:   friend class NonStaticFieldFiller;
duke@435: 
duke@435: private:
duke@435:   ciFlags          _flags;
duke@435:   ciInstanceKlass* _holder;
duke@435:   ciSymbol*        _name;
duke@435:   ciSymbol*        _signature;
duke@435:   ciType*          _type;
duke@435:   int              _offset;
duke@435:   bool             _is_constant;
duke@435:   ciInstanceKlass* _known_to_link_with;
duke@435:   ciConstant       _constant_value;
duke@435: 
duke@435:   // Used for will_link
duke@435:   int              _cp_index;
duke@435: 
duke@435:   ciType* compute_type();
duke@435:   ciType* compute_type_impl();
duke@435: 
duke@435:   ciField(ciInstanceKlass* klass, int index);
duke@435:   ciField(fieldDescriptor* fd);
duke@435: 
duke@435:   // shared constructor code
duke@435:   void initialize_from(fieldDescriptor* fd);
duke@435: 
duke@435:   // The implementation of the print method.
duke@435:   void print_impl(outputStream* st);
duke@435: 
duke@435: public:
duke@435:   ciFlags flags() { return _flags; }
duke@435: 
duke@435:   // Of which klass is this field a member?
duke@435:   //
duke@435:   // Usage note: the declared holder of a field is the class
duke@435:   // referenced by name in the bytecodes.  The canonical holder
duke@435:   // is the most general class which holds the field.  This
duke@435:   // method returns the canonical holder.  The declared holder
duke@435:   // can be accessed via a method in ciBytecodeStream.
duke@435:   //
duke@435:   // Ex.
duke@435:   //     class A {
duke@435:   //       public int f = 7;
duke@435:   //     }
duke@435:   //     class B extends A {
duke@435:   //       public void test() {
duke@435:   //         System.out.println(f);
duke@435:   //       }
duke@435:   //     }
duke@435:   //
duke@435:   //   A java compiler is permitted to compile the access to
duke@435:   //   field f as:
duke@435:   //
duke@435:   //     getfield B.f
duke@435:   //
duke@435:   //   In that case the declared holder of f would be B and
duke@435:   //   the canonical holder of f would be A.
duke@435:   ciInstanceKlass* holder() { return _holder; }
duke@435: 
duke@435:   // Name of this field?
duke@435:   ciSymbol* name() { return _name; }
duke@435: 
duke@435:   // Signature of this field?
duke@435:   ciSymbol* signature() { return _signature; }
duke@435: 
duke@435:   // Of what type is this field?
duke@435:   ciType* type() { return (_type == NULL) ? compute_type() : _type; }
duke@435: 
duke@435:   // How is this field actually stored in memory?
duke@435:   BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; }
duke@435: 
duke@435:   // How big is this field in memory?
kvn@464:   int size_in_bytes() { return type2aelembytes(layout_type()); }
duke@435: 
duke@435:   // What is the offset of this field?
duke@435:   int offset() {
duke@435:     assert(_offset >= 1, "illegal call to offset()");
duke@435:     return _offset;
duke@435:   }
duke@435: 
duke@435:   // Same question, explicit units.  (Fields are aligned to the byte level.)
duke@435:   int offset_in_bytes() {
duke@435:     return offset();
duke@435:   }
duke@435: 
duke@435:   // Is this field shared?
duke@435:   bool is_shared() {
duke@435:     // non-static fields of shared holders are cached
duke@435:     return _holder->is_shared() && !is_static();
duke@435:   }
duke@435: 
duke@435:   // Is this field a constant?
duke@435:   //
duke@435:   // Clarification: A field is considered constant if:
duke@435:   //   1. The field is both static and final
duke@435:   //   2. The canonical holder of the field has undergone
duke@435:   //      static initialization.
duke@435:   //   3. If the field is an object or array, then the oop
duke@435:   //      in question is allocated in perm space.
duke@435:   //   4. The field is not one of the special static/final
duke@435:   //      non-constant fields.  These are java.lang.System.in
duke@435:   //      and java.lang.System.out.  Abomination.
duke@435:   //
duke@435:   // Note: the check for case 4 is not yet implemented.
duke@435:   bool is_constant() { return _is_constant; }
duke@435: 
duke@435:   // Get the constant value of this field.
duke@435:   ciConstant constant_value() {
twisti@1573:     assert(is_static() && is_constant(), "illegal call to constant_value()");
duke@435:     return _constant_value;
duke@435:   }
duke@435: 
twisti@1573:   // Get the constant value of non-static final field in the given
twisti@1573:   // object.
twisti@1573:   ciConstant constant_value_of(ciObject* object) {
twisti@1573:     assert(!is_static() && is_constant(), "only if field is non-static constant");
twisti@1573:     assert(object->is_instance(), "must be instance");
twisti@1573:     return object->as_instance()->field_value(this);
twisti@1573:   }
twisti@1573: 
duke@435:   // Check for link time errors.  Accessing a field from a
duke@435:   // certain class via a certain bytecode may or may not be legal.
duke@435:   // This call checks to see if an exception may be raised by
duke@435:   // an access of this field.
duke@435:   //
duke@435:   // Usage note: if the same field is accessed multiple times
duke@435:   // in the same compilation, will_link will need to be checked
duke@435:   // at each point of access.
duke@435:   bool will_link(ciInstanceKlass* accessing_klass,
duke@435:                  Bytecodes::Code bc);
duke@435: 
duke@435:   // Java access flags
duke@435:   bool is_public      () { return flags().is_public(); }
duke@435:   bool is_private     () { return flags().is_private(); }
duke@435:   bool is_protected   () { return flags().is_protected(); }
duke@435:   bool is_static      () { return flags().is_static(); }
duke@435:   bool is_final       () { return flags().is_final(); }
duke@435:   bool is_volatile    () { return flags().is_volatile(); }
duke@435:   bool is_transient   () { return flags().is_transient(); }
duke@435: 
duke@435:   // Debugging output
duke@435:   void print();
duke@435:   void print_name_on(outputStream* st);
duke@435: };