1 /*
   2  * Copyright (c) 2016, 2017, 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 #ifndef SHARE_GC_Z_ZBITMAP_INLINE_HPP
  25 #define SHARE_GC_Z_ZBITMAP_INLINE_HPP
  26 
  27 #include "gc/z/zBitMap.hpp"
  28 #include "runtime/atomic.hpp"
  29 #include "utilities/bitMap.inline.hpp"
  30 #include "utilities/debug.hpp"
  31 
  32 inline ZBitMap::ZBitMap(idx_t size_in_bits) :
  33     CHeapBitMap(size_in_bits, mtGC, false /* clear */) {}
  34 
  35 inline BitMap::bm_word_t ZBitMap::bit_mask_pair(idx_t bit) {
  36   assert(bit_in_word(bit) < BitsPerWord - 1, "Invalid bit index");
  37   return (bm_word_t)3 << bit_in_word(bit);
  38 }
  39 
  40 inline bool ZBitMap::par_set_bit_pair_finalizable(idx_t bit, bool& inc_live) {
  41   inc_live = par_set_bit(bit);
  42   return inc_live;
  43 }
  44 
  45 inline bool ZBitMap::par_set_bit_pair_strong(idx_t bit, bool& inc_live) {
  46   verify_index(bit);
  47   volatile bm_word_t* const addr = word_addr(bit);
  48   const bm_word_t pair_mask = bit_mask_pair(bit);
  49   bm_word_t old_val = *addr;
  50 
  51   do {
  52     const bm_word_t new_val = old_val | pair_mask;
  53     if (new_val == old_val) {
  54       inc_live = false;
  55       return false;     // Someone else beat us to it.
  56     }
  57     const bm_word_t cur_val = Atomic::cmpxchg(new_val, addr, old_val);
  58     if (cur_val == old_val) {
  59       const bm_word_t marked_mask = bit_mask(bit);
  60       inc_live = !(old_val & marked_mask);
  61       return true;      // Success.
  62     }
  63     old_val = cur_val;  // The value changed, try again.
  64   } while (true);
  65 }
  66 
  67 inline bool ZBitMap::par_set_bit_pair(idx_t bit, bool finalizable, bool& inc_live) {
  68   if (finalizable) {
  69     return par_set_bit_pair_finalizable(bit, inc_live);
  70   } else {
  71     return par_set_bit_pair_strong(bit, inc_live);
  72   }
  73 }
  74 
  75 #endif // SHARE_GC_Z_ZBITMAP_INLINE_HPP