1 /*

     2  * Copyright (c) 1997, 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 

    25 #include "precompiled.hpp"

    26 #include "memory/allocation.inline.hpp"

    27 #include "memory/resourceArea.hpp"

    28 #include "runtime/atomic.hpp"

    29 #include "utilities/bitMap.inline.hpp"

    30 #include "utilities/copy.hpp"

    31 #include "utilities/debug.hpp"

    32 

    33 STATIC_ASSERT(sizeof(BitMap::bm_word_t) == BytesPerWord); // "Implementation assumption."

    34 

    35 typedef BitMap::bm_word_t bm_word_t;

    36 typedef BitMap::idx_t     idx_t;

    37 

    38 class ResourceBitMapAllocator : StackObj {

    39  public:

    40   bm_word_t* allocate(idx_t size_in_words) const {

    41     return NEW_RESOURCE_ARRAY(bm_word_t, size_in_words);

    42   }

    43   void free(bm_word_t* map, idx_t size_in_words) const {

    44     // Don't free resource allocated arrays.

    45   }

    46 };

    47 

    48 class CHeapBitMapAllocator : StackObj {

    49   MEMFLAGS _flags;

    50 

    51  public:

    52   CHeapBitMapAllocator(MEMFLAGS flags) : _flags(flags) {}

    53   bm_word_t* allocate(size_t size_in_words) const {

    54     return ArrayAllocator<bm_word_t>::allocate(size_in_words, _flags);

    55   }

    56   void free(bm_word_t* map, idx_t size_in_words) const {

    57     ArrayAllocator<bm_word_t>::free(map, size_in_words);

    58   }

    59 };

    60 

    61 class ArenaBitMapAllocator : StackObj {

    62   Arena* _arena;

    63 

    64  public:

    65   ArenaBitMapAllocator(Arena* arena) : _arena(arena) {}

    66   bm_word_t* allocate(idx_t size_in_words) const {

    67     return (bm_word_t*)_arena->Amalloc(size_in_words * BytesPerWord);

    68   }

    69   void free(bm_word_t* map, idx_t size_in_words) const {

    70     // ArenaBitMaps currently don't free memory.

    71   }

    72 };

    73 

    74 template <class Allocator>

    75 BitMap::bm_word_t* BitMap::reallocate(const Allocator& allocator, bm_word_t* old_map, idx_t old_size_in_bits, idx_t new_size_in_bits) {

    76   size_t old_size_in_words = calc_size_in_words(old_size_in_bits);

    77   size_t new_size_in_words = calc_size_in_words(new_size_in_bits);

    78 

    79   bm_word_t* map = NULL;

    80 

    81   if (new_size_in_words > 0) {

    82     map = allocator.allocate(new_size_in_words);

    83 

    84     Copy::disjoint_words((HeapWord*)old_map, (HeapWord*) map,

    85                          MIN2(old_size_in_words, new_size_in_words));

    86 

    87     if (new_size_in_words > old_size_in_words) {

    88       clear_range_of_words(map, old_size_in_words, new_size_in_words);

    89     }

    90   }

    91 

    92   if (old_map != NULL) {

    93     allocator.free(old_map, old_size_in_words);

    94   }

    95 

    96   return map;

    97 }

    98 

    99 template <class Allocator>

   100 bm_word_t* BitMap::allocate(const Allocator& allocator, idx_t size_in_bits) {

   101   // Reuse reallocate to ensure that the new memory is cleared.

   102   return reallocate(allocator, NULL, 0, size_in_bits);

   103 }

   104 

   105 template <class Allocator>

   106 void BitMap::free(const Allocator& allocator, bm_word_t* map, idx_t  size_in_bits) {

   107   bm_word_t* ret = reallocate(allocator, map, size_in_bits, 0);

   108   assert(ret == NULL, "Reallocate shouldn't have allocated");

   109 }

   110 

   111 template <class Allocator>

   112 void BitMap::resize(const Allocator& allocator, idx_t new_size_in_bits) {

   113   bm_word_t* new_map = reallocate(allocator, map(), size(), new_size_in_bits);

   114 

   115   update(new_map, new_size_in_bits);

   116 }

   117 

   118 template <class Allocator>

   119 void BitMap::initialize(const Allocator& allocator, idx_t size_in_bits) {

   120   assert(map() == NULL, "precondition");

   121   assert(size() == 0,   "precondition");

   122 

   123   resize(allocator, size_in_bits);

   124 }

   125 

   126 template <class Allocator>

   127 void BitMap::reinitialize(const Allocator& allocator, idx_t new_size_in_bits) {

   128   // Remove previous bits.

   129   resize(allocator, 0);

   130 

   131   initialize(allocator, new_size_in_bits);

   132 }

   133 

   134 ResourceBitMap::ResourceBitMap(idx_t size_in_bits)

   135     : BitMap(allocate(ResourceBitMapAllocator(), size_in_bits), size_in_bits) {

   136 }

   137 

   138 void ResourceBitMap::resize(idx_t new_size_in_bits) {

   139   BitMap::resize(ResourceBitMapAllocator(), new_size_in_bits);

   140 }

   141 

   142 void ResourceBitMap::initialize(idx_t size_in_bits) {

   143   BitMap::initialize(ResourceBitMapAllocator(), size_in_bits);

   144 }

   145 

   146 void ResourceBitMap::reinitialize(idx_t size_in_bits) {

   147   BitMap::reinitialize(ResourceBitMapAllocator(), size_in_bits);

   148 }

   149 

   150 ArenaBitMap::ArenaBitMap(Arena* arena, idx_t size_in_bits)

   151     : BitMap(allocate(ArenaBitMapAllocator(arena), size_in_bits), size_in_bits) {

   152 }

   153 

   154 CHeapBitMap::CHeapBitMap(idx_t size_in_bits, MEMFLAGS flags)

   155     : BitMap(allocate(CHeapBitMapAllocator(flags), size_in_bits), size_in_bits), _flags(flags) {

   156 }

   157 

   158 CHeapBitMap::~CHeapBitMap() {

   159   free(CHeapBitMapAllocator(_flags), map(), size());

   160 }

   161 

   162 void CHeapBitMap::resize(idx_t new_size_in_bits) {

   163   BitMap::resize(CHeapBitMapAllocator(_flags), new_size_in_bits);

   164 }

   165 

   166 void CHeapBitMap::initialize(idx_t size_in_bits) {

   167   BitMap::initialize(CHeapBitMapAllocator(_flags), size_in_bits);

   168 }

   169 

   170 void CHeapBitMap::reinitialize(idx_t size_in_bits) {

   171   BitMap::reinitialize(CHeapBitMapAllocator(_flags), size_in_bits);

   172 }

   173 

   174 #ifdef ASSERT

   175 void BitMap::verify_index(idx_t index) const {

   176   assert(index < _size, "BitMap index out of bounds");

   177 }

   178 

   179 void BitMap::verify_range(idx_t beg_index, idx_t end_index) const {

   180   assert(beg_index <= end_index, "BitMap range error");

   181   // Note that [0,0) and [size,size) are both valid ranges.

   182   if (end_index != _size) verify_index(end_index);

   183 }

   184 #endif // #ifdef ASSERT

   185 

   186 void BitMap::pretouch() {

   187   os::pretouch_memory(word_addr(0), word_addr(size()));

   188 }

   189 

   190 void BitMap::set_range_within_word(idx_t beg, idx_t end) {

   191   // With a valid range (beg <= end), this test ensures that end != 0, as

   192   // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.

   193   if (beg != end) {

   194     bm_word_t mask = inverted_bit_mask_for_range(beg, end);

   195     *word_addr(beg) |= ~mask;

   196   }

   197 }

   198 

   199 void BitMap::clear_range_within_word(idx_t beg, idx_t end) {

   200   // With a valid range (beg <= end), this test ensures that end != 0, as

   201   // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.

   202   if (beg != end) {

   203     bm_word_t mask = inverted_bit_mask_for_range(beg, end);

   204     *word_addr(beg) &= mask;

   205   }

   206 }

   207 

   208 void BitMap::par_put_range_within_word(idx_t beg, idx_t end, bool value) {

   209   assert(value == 0 || value == 1, "0 for clear, 1 for set");

   210   // With a valid range (beg <= end), this test ensures that end != 0, as

   211   // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.

   212   if (beg != end) {

   213     bm_word_t* pw = word_addr(beg);

   214     bm_word_t  w  = *pw;

   215     bm_word_t  mr = inverted_bit_mask_for_range(beg, end);

   216     bm_word_t  nw = value ? (w | ~mr) : (w & mr);

   217     while (true) {

   218       bm_word_t res = Atomic::cmpxchg(nw, pw, w);

   219       if (res == w) break;

   220       w  = res;

   221       nw = value ? (w | ~mr) : (w & mr);

   222     }

   223   }

   224 }

   225 

   226 void BitMap::set_range(idx_t beg, idx_t end) {

   227   verify_range(beg, end);

   228 

   229   idx_t beg_full_word = word_index_round_up(beg);

   230   idx_t end_full_word = word_index(end);

   231 

   232   if (beg_full_word < end_full_word) {

   233     // The range includes at least one full word.

   234     set_range_within_word(beg, bit_index(beg_full_word));

   235     set_range_of_words(beg_full_word, end_full_word);

   236     set_range_within_word(bit_index(end_full_word), end);

   237   } else {

   238     // The range spans at most 2 partial words.

   239     idx_t boundary = MIN2(bit_index(beg_full_word), end);

   240     set_range_within_word(beg, boundary);

   241     set_range_within_word(boundary, end);

   242   }

   243 }

   244 

   245 void BitMap::clear_range(idx_t beg, idx_t end) {

   246   verify_range(beg, end);

   247 

   248   idx_t beg_full_word = word_index_round_up(beg);

   249   idx_t end_full_word = word_index(end);

   250 

   251   if (beg_full_word < end_full_word) {

   252     // The range includes at least one full word.

   253     clear_range_within_word(beg, bit_index(beg_full_word));

   254     clear_range_of_words(beg_full_word, end_full_word);

   255     clear_range_within_word(bit_index(end_full_word), end);

   256   } else {

   257     // The range spans at most 2 partial words.

   258     idx_t boundary = MIN2(bit_index(beg_full_word), end);

   259     clear_range_within_word(beg, boundary);

   260     clear_range_within_word(boundary, end);

   261   }

   262 }

   263 

   264 void BitMap::set_large_range(idx_t beg, idx_t end) {

   265   verify_range(beg, end);

   266 

   267   idx_t beg_full_word = word_index_round_up(beg);

   268   idx_t end_full_word = word_index(end);

   269 

   270   assert(end_full_word - beg_full_word >= 32,

   271          "the range must include at least 32 bytes");

   272 

   273   // The range includes at least one full word.

   274   set_range_within_word(beg, bit_index(beg_full_word));

   275   set_large_range_of_words(beg_full_word, end_full_word);

   276   set_range_within_word(bit_index(end_full_word), end);

   277 }

   278 

   279 void BitMap::clear_large_range(idx_t beg, idx_t end) {

   280   verify_range(beg, end);

   281 

   282   idx_t beg_full_word = word_index_round_up(beg);

   283   idx_t end_full_word = word_index(end);

   284 

   285   if (end_full_word - beg_full_word < 32) {

   286     clear_range(beg, end);

   287     return;

   288   }

   289 

   290   // The range includes at least one full word.

   291   clear_range_within_word(beg, bit_index(beg_full_word));

   292   clear_large_range_of_words(beg_full_word, end_full_word);

   293   clear_range_within_word(bit_index(end_full_word), end);

   294 }

   295 

   296 void BitMap::at_put(idx_t offset, bool value) {

   297   if (value) {

   298     set_bit(offset);

   299   } else {

   300     clear_bit(offset);

   301   }

   302 }

   303 

   304 // Return true to indicate that this thread changed

   305 // the bit, false to indicate that someone else did.

   306 // In either case, the requested bit is in the

   307 // requested state some time during the period that

   308 // this thread is executing this call. More importantly,

   309 // if no other thread is executing an action to

   310 // change the requested bit to a state other than

   311 // the one that this thread is trying to set it to,

   312 // then the the bit is in the expected state

   313 // at exit from this method. However, rather than

   314 // make such a strong assertion here, based on

   315 // assuming such constrained use (which though true

   316 // today, could change in the future to service some

   317 // funky parallel algorithm), we encourage callers

   318 // to do such verification, as and when appropriate.

   319 bool BitMap::par_at_put(idx_t bit, bool value) {

   320   return value ? par_set_bit(bit) : par_clear_bit(bit);

   321 }

   322 

   323 void BitMap::at_put_range(idx_t start_offset, idx_t end_offset, bool value) {

   324   if (value) {

   325     set_range(start_offset, end_offset);

   326   } else {

   327     clear_range(start_offset, end_offset);

   328   }

   329 }

   330 

   331 void BitMap::par_at_put_range(idx_t beg, idx_t end, bool value) {

   332   verify_range(beg, end);

   333 

   334   idx_t beg_full_word = word_index_round_up(beg);

   335   idx_t end_full_word = word_index(end);

   336 

   337   if (beg_full_word < end_full_word) {

   338     // The range includes at least one full word.

   339     par_put_range_within_word(beg, bit_index(beg_full_word), value);

   340     if (value) {

   341       set_range_of_words(beg_full_word, end_full_word);

   342     } else {

   343       clear_range_of_words(beg_full_word, end_full_word);

   344     }

   345     par_put_range_within_word(bit_index(end_full_word), end, value);

   346   } else {

   347     // The range spans at most 2 partial words.

   348     idx_t boundary = MIN2(bit_index(beg_full_word), end);

   349     par_put_range_within_word(beg, boundary, value);

   350     par_put_range_within_word(boundary, end, value);

   351   }

   352 

   353 }

   354 

   355 void BitMap::at_put_large_range(idx_t beg, idx_t end, bool value) {

   356   if (value) {

   357     set_large_range(beg, end);

   358   } else {

   359     clear_large_range(beg, end);

   360   }

   361 }

   362 

   363 void BitMap::par_at_put_large_range(idx_t beg, idx_t end, bool value) {

   364   verify_range(beg, end);

   365 

   366   idx_t beg_full_word = word_index_round_up(beg);

   367   idx_t end_full_word = word_index(end);

   368 

   369   assert(end_full_word - beg_full_word >= 32,

   370          "the range must include at least 32 bytes");

   371 

   372   // The range includes at least one full word.

   373   par_put_range_within_word(beg, bit_index(beg_full_word), value);

   374   if (value) {

   375     set_large_range_of_words(beg_full_word, end_full_word);

   376   } else {

   377     clear_large_range_of_words(beg_full_word, end_full_word);

   378   }

   379   par_put_range_within_word(bit_index(end_full_word), end, value);

   380 }

   381 

   382 inline bm_word_t tail_mask(idx_t tail_bits) {

   383   assert(tail_bits != 0, "precondition"); // Works, but shouldn't be called.

   384   assert(tail_bits < (idx_t)BitsPerWord, "precondition");

   385   return (bm_word_t(1) << tail_bits) - 1;

   386 }

   387 

   388 // Get the low tail_bits of value, which is the last partial word of a map.

   389 inline bm_word_t tail_of_map(bm_word_t value, idx_t tail_bits) {

   390   return value & tail_mask(tail_bits);

   391 }

   392 

   393 // Compute the new last word of a map with a non-aligned length.

   394 // new_value has the new trailing bits of the map in the low tail_bits.

   395 // old_value is the last word of the map, including bits beyond the end.

   396 // Returns old_value with the low tail_bits replaced by the corresponding

   397 // bits in new_value.

   398 inline bm_word_t merge_tail_of_map(bm_word_t new_value,

   399                                    bm_word_t old_value,

   400                                    idx_t tail_bits) {

   401   bm_word_t mask = tail_mask(tail_bits);

   402   return (new_value & mask) | (old_value & ~mask);

   403 }

   404 

   405 bool BitMap::contains(const BitMap& other) const {

   406   assert(size() == other.size(), "must have same size");

   407   const bm_word_t* dest_map = map();

   408   const bm_word_t* other_map = other.map();

   409   idx_t limit = word_index(size());

   410   for (idx_t index = 0; index < limit; ++index) {

   411     // false if other bitmap has bits set which are clear in this bitmap.

   412     if ((~dest_map[index] & other_map[index]) != 0) return false;

   413   }

   414   idx_t rest = bit_in_word(size());

   415   // true unless there is a partial-word tail in which the other

   416   // bitmap has bits set which are clear in this bitmap.

   417   return (rest == 0) || tail_of_map(~dest_map[limit] & other_map[limit], rest) == 0;

   418 }

   419 

   420 bool BitMap::intersects(const BitMap& other) const {

   421   assert(size() == other.size(), "must have same size");

   422   const bm_word_t* dest_map = map();

   423   const bm_word_t* other_map = other.map();

   424   idx_t limit = word_index(size());

   425   for (idx_t index = 0; index < limit; ++index) {

   426     if ((dest_map[index] & other_map[index]) != 0) return true;

   427   }

   428   idx_t rest = bit_in_word(size());

   429   // false unless there is a partial-word tail with non-empty intersection.

   430   return (rest > 0) && tail_of_map(dest_map[limit] & other_map[limit], rest) != 0;

   431 }

   432 

   433 void BitMap::set_union(const BitMap& other) {

   434   assert(size() == other.size(), "must have same size");

   435   bm_word_t* dest_map = map();

   436   const bm_word_t* other_map = other.map();

   437   idx_t limit = word_index(size());

   438   for (idx_t index = 0; index < limit; ++index) {

   439     dest_map[index] |= other_map[index];

   440   }

   441   idx_t rest = bit_in_word(size());

   442   if (rest > 0) {

   443     bm_word_t orig = dest_map[limit];

   444     dest_map[limit] = merge_tail_of_map(orig | other_map[limit], orig, rest);

   445   }

   446 }

   447 

   448 void BitMap::set_difference(const BitMap& other) {

   449   assert(size() == other.size(), "must have same size");

   450   bm_word_t* dest_map = map();

   451   const bm_word_t* other_map = other.map();

   452   idx_t limit = word_index(size());

   453   for (idx_t index = 0; index < limit; ++index) {

   454     dest_map[index] &= ~other_map[index];

   455   }

   456   idx_t rest = bit_in_word(size());

   457   if (rest > 0) {

   458     bm_word_t orig = dest_map[limit];

   459     dest_map[limit] = merge_tail_of_map(orig & ~other_map[limit], orig, rest);

   460   }

   461 }

   462 

   463 void BitMap::set_intersection(const BitMap& other) {

   464   assert(size() == other.size(), "must have same size");

   465   bm_word_t* dest_map = map();

   466   const bm_word_t* other_map = other.map();

   467   idx_t limit = word_index(size());

   468   for (idx_t index = 0; index < limit; ++index) {

   469     dest_map[index] &= other_map[index];

   470   }

   471   idx_t rest = bit_in_word(size());

   472   if (rest > 0) {

   473     bm_word_t orig = dest_map[limit];

   474     dest_map[limit] = merge_tail_of_map(orig & other_map[limit], orig, rest);

   475   }

   476 }

   477 

   478 bool BitMap::set_union_with_result(const BitMap& other) {

   479   assert(size() == other.size(), "must have same size");

   480   bool changed = false;

   481   bm_word_t* dest_map = map();

   482   const bm_word_t* other_map = other.map();

   483   idx_t limit = word_index(size());

   484   for (idx_t index = 0; index < limit; ++index) {

   485     bm_word_t orig = dest_map[index];

   486     bm_word_t temp = orig | other_map[index];

   487     changed = changed || (temp != orig);

   488     dest_map[index] = temp;

   489   }

   490   idx_t rest = bit_in_word(size());

   491   if (rest > 0) {

   492     bm_word_t orig = dest_map[limit];

   493     bm_word_t temp = merge_tail_of_map(orig | other_map[limit], orig, rest);

   494     changed = changed || (temp != orig);

   495     dest_map[limit] = temp;

   496   }

   497   return changed;

   498 }

   499 

   500 bool BitMap::set_difference_with_result(const BitMap& other) {

   501   assert(size() == other.size(), "must have same size");

   502   bool changed = false;

   503   bm_word_t* dest_map = map();

   504   const bm_word_t* other_map = other.map();

   505   idx_t limit = word_index(size());

   506   for (idx_t index = 0; index < limit; ++index) {

   507     bm_word_t orig = dest_map[index];

   508     bm_word_t temp = orig & ~other_map[index];

   509     changed = changed || (temp != orig);

   510     dest_map[index] = temp;

   511   }

   512   idx_t rest = bit_in_word(size());

   513   if (rest > 0) {

   514     bm_word_t orig = dest_map[limit];

   515     bm_word_t temp = merge_tail_of_map(orig & ~other_map[limit], orig, rest);

   516     changed = changed || (temp != orig);

   517     dest_map[limit] = temp;

   518   }

   519   return changed;

   520 }

   521 

   522 bool BitMap::set_intersection_with_result(const BitMap& other) {

   523   assert(size() == other.size(), "must have same size");

   524   bool changed = false;

   525   bm_word_t* dest_map = map();

   526   const bm_word_t* other_map = other.map();

   527   idx_t limit = word_index(size());

   528   for (idx_t index = 0; index < limit; ++index) {

   529     bm_word_t orig = dest_map[index];

   530     bm_word_t temp = orig & other_map[index];

   531     changed = changed || (temp != orig);

   532     dest_map[index] = temp;

   533   }

   534   idx_t rest = bit_in_word(size());

   535   if (rest > 0) {

   536     bm_word_t orig = dest_map[limit];

   537     bm_word_t temp = merge_tail_of_map(orig & other_map[limit], orig, rest);

   538     changed = changed || (temp != orig);

   539     dest_map[limit] = temp;

   540   }

   541   return changed;

   542 }

   543 

   544 void BitMap::set_from(const BitMap& other) {

   545   assert(size() == other.size(), "must have same size");

   546   bm_word_t* dest_map = map();

   547   const bm_word_t* other_map = other.map();

   548   idx_t copy_words = word_index(size());

   549   Copy::disjoint_words((HeapWord*)other_map, (HeapWord*)dest_map, copy_words);

   550   idx_t rest = bit_in_word(size());

   551   if (rest > 0) {

   552     dest_map[copy_words] = merge_tail_of_map(other_map[copy_words],

   553                                              dest_map[copy_words],

   554                                              rest);

   555   }

   556 }

   557 

   558 bool BitMap::is_same(const BitMap& other) const {

   559   assert(size() == other.size(), "must have same size");

   560   const bm_word_t* dest_map = map();

   561   const bm_word_t* other_map = other.map();

   562   idx_t limit = word_index(size());

   563   for (idx_t index = 0; index < limit; ++index) {

   564     if (dest_map[index] != other_map[index]) return false;

   565   }

   566   idx_t rest = bit_in_word(size());

   567   return (rest == 0) || (tail_of_map(dest_map[limit] ^ other_map[limit], rest) == 0);

   568 }

   569 

   570 bool BitMap::is_full() const {

   571   const bm_word_t* words = map();

   572   idx_t limit = word_index(size());

   573   for (idx_t index = 0; index < limit; ++index) {

   574     if (~words[index] != 0) return false;

   575   }

   576   idx_t rest = bit_in_word(size());

   577   return (rest == 0) || (tail_of_map(~words[limit], rest) == 0);

   578 }

   579 

   580 bool BitMap::is_empty() const {

   581   const bm_word_t* words = map();

   582   idx_t limit = word_index(size());

   583   for (idx_t index = 0; index < limit; ++index) {

   584     if (words[index] != 0) return false;

   585   }

   586   idx_t rest = bit_in_word(size());

   587   return (rest == 0) || (tail_of_map(words[limit], rest) == 0);

   588 }

   589 

   590 void BitMap::clear_large() {

   591   clear_large_range_of_words(0, size_in_words());

   592 }

   593 

   594 // Note that if the closure itself modifies the bitmap

   595 // then modifications in and to the left of the _bit_ being

   596 // currently sampled will not be seen. Note also that the

   597 // interval [leftOffset, rightOffset) is right open.

   598 bool BitMap::iterate(BitMapClosure* blk, idx_t leftOffset, idx_t rightOffset) {

   599   verify_range(leftOffset, rightOffset);

   600 

   601   idx_t startIndex = word_index(leftOffset);

   602   idx_t endIndex   = MIN2(word_index(rightOffset) + 1, size_in_words());

   603   for (idx_t index = startIndex, offset = leftOffset;

   604        offset < rightOffset && index < endIndex;

   605        offset = (++index) << LogBitsPerWord) {

   606     idx_t rest = map(index) >> (offset & (BitsPerWord - 1));

   607     for (; offset < rightOffset && rest != 0; offset++) {

   608       if (rest & 1) {

   609         if (!blk->do_bit(offset)) return false;

   610         //  resample at each closure application

   611         // (see, for instance, CMS bug 4525989)

   612         rest = map(index) >> (offset & (BitsPerWord -1));

   613       }

   614       rest = rest >> 1;

   615     }

   616   }

   617   return true;

   618 }

   619 

   620 const BitMap::idx_t* BitMap::_pop_count_table = NULL;

   621 

   622 void BitMap::init_pop_count_table() {

   623   if (_pop_count_table == NULL) {

   624     BitMap::idx_t *table = NEW_C_HEAP_ARRAY(idx_t, 256, mtInternal);

   625     for (uint i = 0; i < 256; i++) {

   626       table[i] = num_set_bits(i);

   627     }

   628 

   629     if (!Atomic::replace_if_null(table, &_pop_count_table)) {

   630       guarantee(_pop_count_table != NULL, "invariant");

   631       FREE_C_HEAP_ARRAY(idx_t, table);

   632     }

   633   }

   634 }

   635 

   636 BitMap::idx_t BitMap::num_set_bits(bm_word_t w) {

   637   idx_t bits = 0;

   638 

   639   while (w != 0) {

   640     while ((w & 1) == 0) {

   641       w >>= 1;

   642     }

   643     bits++;

   644     w >>= 1;

   645   }

   646   return bits;

   647 }

   648 

   649 BitMap::idx_t BitMap::num_set_bits_from_table(unsigned char c) {

   650   assert(_pop_count_table != NULL, "precondition");

   651   return _pop_count_table[c];

   652 }

   653 

   654 BitMap::idx_t BitMap::count_one_bits() const {

   655   init_pop_count_table(); // If necessary.

   656   idx_t sum = 0;

   657   typedef unsigned char uchar;

   658   for (idx_t i = 0; i < size_in_words(); i++) {

   659     bm_word_t w = map()[i];

   660     for (size_t j = 0; j < sizeof(bm_word_t); j++) {

   661       sum += num_set_bits_from_table(uchar(w & 255));

   662       w >>= 8;

   663     }

   664   }

   665   return sum;

   666 }

   667 

   668 void BitMap::print_on_error(outputStream* st, const char* prefix) const {

   669   st->print_cr("%s[" PTR_FORMAT ", " PTR_FORMAT ")",

   670       prefix, p2i(map()), p2i((char*)map() + (size() >> LogBitsPerByte)));

   671 }

   672 

   673 #ifndef PRODUCT

   674 

   675 void BitMap::print_on(outputStream* st) const {

   676   tty->print("Bitmap(" SIZE_FORMAT "):", size());

   677   for (idx_t index = 0; index < size(); index++) {

   678     tty->print("%c", at(index) ? '1' : '0');

   679   }

   680   tty->cr();

   681 }

   682 

   683 #endif