/*

 * Copyright (c) 2011, 2019, 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_OOPS_FIELDINFO_HPP

#define SHARE_OOPS_FIELDINFO_HPP

#include "oops/constantPool.hpp"

#include "oops/typeArrayOop.hpp"

#include "classfile/vmSymbols.hpp"

// This class represents the field information contained in the fields

// array of an InstanceKlass.  Currently it's laid on top an array of

// Java shorts but in the future it could simply be used as a real

// array type.  FieldInfo generally shouldn't be used directly.

// Fields should be queried either through InstanceKlass or through

// the various FieldStreams.

class FieldInfo {

  friend class fieldDescriptor;

  friend class JavaFieldStream;

  friend class ClassFileParser;

 public:

  // fields

  // Field info extracted from the class file and stored

  // as an array of 6 shorts.

#define FIELDINFO_TAG_SIZE             2

#define FIELDINFO_TAG_BLANK            0

#define FIELDINFO_TAG_OFFSET           1

#define FIELDINFO_TAG_TYPE_PLAIN       2

#define FIELDINFO_TAG_TYPE_CONTENDED   3

#define FIELDINFO_TAG_MASK             3

  // Packed field has the tag, and can be either of:

  //    hi bits <--------------------------- lo bits

  //   |---------high---------|---------low---------|

  //    ..........................................00  - blank

  //    [------------------offset----------------]01  - real field offset

  //    ......................[-------type-------]10  - plain field with type

  //    [--contention_group--][-------type-------]11  - contended field with type and contention group

  enum FieldOffset {

    access_flags_offset      = 0,

    name_index_offset        = 1,

    signature_index_offset   = 2,

    initval_index_offset     = 3,

    low_packed_offset        = 4,

    high_packed_offset       = 5,

    field_slots              = 6

  };

 private:

  u2 _shorts[field_slots];

  void set_name_index(u2 val)                    { _shorts[name_index_offset] = val;         }

  void set_signature_index(u2 val)               { _shorts[signature_index_offset] = val;    }

  void set_initval_index(u2 val)                 { _shorts[initval_index_offset] = val;      }

  u2 name_index() const                          { return _shorts[name_index_offset];        }

  u2 signature_index() const                     { return _shorts[signature_index_offset];   }

  u2 initval_index() const                       { return _shorts[initval_index_offset];     }

 public:

  static FieldInfo* from_field_array(Array<u2>* fields, int index) {

    return ((FieldInfo*)fields->adr_at(index * field_slots));

  }

  static FieldInfo* from_field_array(u2* fields, int index) {

    return ((FieldInfo*)(fields + index * field_slots));

  }

  void initialize(u2 access_flags,

                  u2 name_index,

                  u2 signature_index,

                  u2 initval_index) {

    _shorts[access_flags_offset] = access_flags;

    _shorts[name_index_offset] = name_index;

    _shorts[signature_index_offset] = signature_index;

    _shorts[initval_index_offset] = initval_index;

    _shorts[low_packed_offset] = 0;

    _shorts[high_packed_offset] = 0;

  }

  u2 access_flags() const                        { return _shorts[access_flags_offset];            }

  u4 offset() const {

    u2 lo = _shorts[low_packed_offset];

    switch(lo & FIELDINFO_TAG_MASK) {

      case FIELDINFO_TAG_OFFSET:

        return build_int_from_shorts(_shorts[low_packed_offset], _shorts[high_packed_offset]) >> FIELDINFO_TAG_SIZE;

#ifndef PRODUCT

      case FIELDINFO_TAG_TYPE_PLAIN:

        fatal("Asking offset for the plain type field");

      case FIELDINFO_TAG_TYPE_CONTENDED:

        fatal("Asking offset for the contended type field");

      case FIELDINFO_TAG_BLANK:

        fatal("Asking offset for the blank field");

#endif

    }

    ShouldNotReachHere();

    return 0;

  }

  bool is_contended() const {

    u2 lo = _shorts[low_packed_offset];

    switch(lo & FIELDINFO_TAG_MASK) {

      case FIELDINFO_TAG_TYPE_PLAIN:

        return false;

      case FIELDINFO_TAG_TYPE_CONTENDED:

        return true;

#ifndef PRODUCT

      case FIELDINFO_TAG_OFFSET:

        fatal("Asking contended flag for the field with offset");

      case FIELDINFO_TAG_BLANK:

        fatal("Asking contended flag for the blank field");

#endif

    }

    ShouldNotReachHere();

    return false;

  }

  u2 contended_group() const {

    u2 lo = _shorts[low_packed_offset];

    switch(lo & FIELDINFO_TAG_MASK) {

      case FIELDINFO_TAG_TYPE_PLAIN:

        return 0;

      case FIELDINFO_TAG_TYPE_CONTENDED:

        return _shorts[high_packed_offset];

#ifndef PRODUCT

      case FIELDINFO_TAG_OFFSET:

        fatal("Asking the contended group for the field with offset");

      case FIELDINFO_TAG_BLANK:

        fatal("Asking the contended group for the blank field");

#endif

    }

    ShouldNotReachHere();

    return 0;

 }

  u2 allocation_type() const {

    u2 lo = _shorts[low_packed_offset];

    switch(lo & FIELDINFO_TAG_MASK) {

      case FIELDINFO_TAG_TYPE_PLAIN:

      case FIELDINFO_TAG_TYPE_CONTENDED:

        return (lo >> FIELDINFO_TAG_SIZE);

#ifndef PRODUCT

      case FIELDINFO_TAG_OFFSET:

        fatal("Asking the field type for field with offset");

      case FIELDINFO_TAG_BLANK:

        fatal("Asking the field type for the blank field");

#endif

    }

    ShouldNotReachHere();

    return 0;

  }

  bool is_offset_set() const {

    return (_shorts[low_packed_offset] & FIELDINFO_TAG_MASK) == FIELDINFO_TAG_OFFSET;

  }

  Symbol* name(const constantPoolHandle& cp) const {

    int index = name_index();

    if (is_internal()) {

      return lookup_symbol(index);

    }

    return cp->symbol_at(index);

  }

  Symbol* signature(const constantPoolHandle& cp) const {

    int index = signature_index();

    if (is_internal()) {

      return lookup_symbol(index);

    }

    return cp->symbol_at(index);

  }

  void set_access_flags(u2 val)                  { _shorts[access_flags_offset] = val;             }

  void set_offset(u4 val)                        {

    val = val << FIELDINFO_TAG_SIZE; // make room for tag

    _shorts[low_packed_offset] = extract_low_short_from_int(val) | FIELDINFO_TAG_OFFSET;

    _shorts[high_packed_offset] = extract_high_short_from_int(val);

  }

  void set_allocation_type(int type) {

    u2 lo = _shorts[low_packed_offset];

    switch(lo & FIELDINFO_TAG_MASK) {

      case FIELDINFO_TAG_BLANK:

        _shorts[low_packed_offset] = ((type << FIELDINFO_TAG_SIZE)) & 0xFFFF;

        _shorts[low_packed_offset] &= ~FIELDINFO_TAG_MASK;

        _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_PLAIN;

        return;

#ifndef PRODUCT

      case FIELDINFO_TAG_TYPE_PLAIN:

      case FIELDINFO_TAG_TYPE_CONTENDED:

      case FIELDINFO_TAG_OFFSET:

        fatal("Setting the field type with overwriting");

#endif

    }

    ShouldNotReachHere();

  }

  void set_contended_group(u2 val) {

    u2 lo = _shorts[low_packed_offset];

    switch(lo & FIELDINFO_TAG_MASK) {

      case FIELDINFO_TAG_TYPE_PLAIN:

        _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_CONTENDED;

        _shorts[high_packed_offset] = val;

        return;

#ifndef PRODUCT

      case FIELDINFO_TAG_TYPE_CONTENDED:

        fatal("Overwriting contended group");

      case FIELDINFO_TAG_BLANK:

        fatal("Setting contended group for the blank field");

      case FIELDINFO_TAG_OFFSET:

        fatal("Setting contended group for field with offset");

#endif

    }

    ShouldNotReachHere();

  }

  bool is_internal() const {

    return (access_flags() & JVM_ACC_FIELD_INTERNAL) != 0;

  }

  bool is_stable() const {

    return (access_flags() & JVM_ACC_FIELD_STABLE) != 0;

  }

  void set_stable(bool z) {

    if (z) _shorts[access_flags_offset] |=  JVM_ACC_FIELD_STABLE;

    else   _shorts[access_flags_offset] &= ~JVM_ACC_FIELD_STABLE;

  }

  Symbol* lookup_symbol(int symbol_index) const {

    assert(is_internal(), "only internal fields");

    return vmSymbols::symbol_at((vmSymbols::SID)symbol_index);

  }

};

#endif // SHARE_OOPS_FIELDINFO_HPP