/*

 * 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

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 */

#include "ci/ciClassList.hpp"

#include "ci/ciConstant.hpp"

#include "ci/ciFlags.hpp"

#include "ci/ciInstance.hpp"

#include "ci/ciUtilities.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;

private:

  ciFlags          _flags;

  ciInstanceKlass* _holder;

  ciSymbol*        _name;

  ciSymbol*        _signature;

  ciType*          _type;

  int              _offset;

  bool             _is_constant;

  ciMethod*        _known_to_link_with_put;

  ciInstanceKlass* _known_to_link_with_get;

  ciConstant       _constant_value;

  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() const { 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() const { return _holder; }

  // Name of this field?

  ciSymbol* name() const { return _name; }

  // Signature of this field?

  ciSymbol* signature() const { 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() const {

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

    return _offset;

  }

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

  int offset_in_bytes() const {

    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 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) or

  // - it is trusted or

  // - it is the target field of a CallSite object.

  //

  // See ciField::initialize_from() for more details.

  //

  // A user should also check the field value (constant_value().is_valid()), since

  // constant fields of non-initialized classes don't have values yet.

  bool is_constant() const { return _is_constant; }

  // Get the constant value of the static field.

  ciConstant constant_value();

  bool is_static_constant() {

    return is_static() && is_constant() && constant_value().is_valid();

  }

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

  // object.

  ciConstant constant_value_of(ciObject* object);

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

  // certain method 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(ciMethod* accessing_method,

                 Bytecodes::Code bc);

  // Java access flags

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

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

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

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

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

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

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

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

  // The field is modified outside of instance initializer methods

  // (or class/initializer methods if the field is static).

  bool has_initialized_final_update() const { return flags().has_initialized_final_update(); }

  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()));

  }

  bool is_autobox_cache() {

    ciSymbol* klass_name = holder()->name();

    return (name() == ciSymbol::cache_field_name() &&

            holder()->uses_default_loader() &&

            (klass_name == ciSymbol::java_lang_Character_CharacterCache() ||

             klass_name == ciSymbol::java_lang_Byte_ByteCache() ||

             klass_name == ciSymbol::java_lang_Short_ShortCache() ||

             klass_name == ciSymbol::java_lang_Integer_IntegerCache() ||

             klass_name == ciSymbol::java_lang_Long_LongCache()));

  }

  // Debugging output

  void print();

  void print_name_on(outputStream* st);

};