1 /*
   2  * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_OOPS_ARRAYSTORAGEPROPERTIES_HPP
  26 #define SHARE_OOPS_ARRAYSTORAGEPROPERTIES_HPP
  27 
  28 #include "runtime/globals.hpp"
  29 
  30 class ArrayStorageProperties {
  31  private:
  32   uint8_t _flags;
  33 
  34   void clear_flags_bits(uint8_t value) { _flags &= (~value); }
  35   void set_flags_bits(uint8_t value) { _flags |= value; }
  36   bool test_flags_bit(int idx) const { return (_flags & (1 << idx)) != 0; }
  37  public:
  38 
  39   enum {
  40     empty_value           = 0,
  41     flattened_bit         = 0,
  42     flattened_value       = 1 <<  flattened_bit,
  43     null_free_bit = flattened_bit + 1,
  44     null_free_value = 1 << null_free_bit,
  45     nof_oop_properties = null_free_bit + 1
  46   };
  47 
  48   ArrayStorageProperties() : _flags(empty_value) {};
  49   ArrayStorageProperties(uint8_t flags): _flags(flags) {};
  50 
  51   bool is_empty() const { return _flags == empty_value; }
  52 
  53   void clear_flattened()    { clear_flags_bits(flattened_value); }
  54 
  55   bool is_flattened() const { return test_flags_bit(flattened_bit); }
  56   void set_flattened()      { set_flags_bits(flattened_value); }
  57 
  58   bool is_null_free() const { return test_flags_bit(null_free_bit); }
  59   void set_null_free()      { set_flags_bits(null_free_value); }
  60 
  61   uint8_t value() const { return _flags; }
  62   template <typename T> T encode(int shift) const { return static_cast<T>(_flags) << shift; }
  63 
  64   // Well-known constants...
  65   static const ArrayStorageProperties empty;
  66   static const ArrayStorageProperties flattened;
  67   static const ArrayStorageProperties null_free;
  68   static const ArrayStorageProperties flattened_and_null_free;
  69 };
  70 
  71 
  72 #endif //SHARE_OOPS_ARRAYSTORAGEPROPERTIES_HPP