hotspot/src/share/vm/utilities/bitMap.cpp
changeset 1 489c9b5090e2
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0:fd16c54261b3 1:489c9b5090e2
       
     1 /*
       
     2  * Copyright 1997-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
       
    20  * CA 95054 USA or visit www.sun.com if you need additional information or
       
    21  * have any questions.
       
    22  *
       
    23  */
       
    24 
       
    25 # include "incls/_precompiled.incl"
       
    26 # include "incls/_bitMap.cpp.incl"
       
    27 
       
    28 
       
    29 BitMap::BitMap(idx_t* map, idx_t size_in_bits) {
       
    30   assert(size_in_bits >= 0, "just checking");
       
    31   _map = map;
       
    32   _size = size_in_bits;
       
    33 }
       
    34 
       
    35 
       
    36 BitMap::BitMap(idx_t size_in_bits) {
       
    37   assert(size_in_bits >= 0, "just checking");
       
    38   _size = size_in_bits;
       
    39   _map = NEW_RESOURCE_ARRAY(idx_t, size_in_words());
       
    40 }
       
    41 
       
    42 
       
    43 void BitMap::resize(idx_t size_in_bits) {
       
    44   assert(size_in_bits >= 0, "just checking");
       
    45   size_t old_size_in_words = size_in_words();
       
    46   uintptr_t* old_map = map();
       
    47   _size = size_in_bits;
       
    48   size_t new_size_in_words = size_in_words();
       
    49   _map = NEW_RESOURCE_ARRAY(idx_t, new_size_in_words);
       
    50   Copy::disjoint_words((HeapWord*) old_map, (HeapWord*) _map, MIN2(old_size_in_words, new_size_in_words));
       
    51   if (new_size_in_words > old_size_in_words) {
       
    52     clear_range_of_words(old_size_in_words, size_in_words());
       
    53   }
       
    54 }
       
    55 
       
    56 // Returns a bit mask for a range of bits [beg, end) within a single word.  Each
       
    57 // bit in the mask is 0 if the bit is in the range, 1 if not in the range.  The
       
    58 // returned mask can be used directly to clear the range, or inverted to set the
       
    59 // range.  Note:  end must not be 0.
       
    60 inline BitMap::idx_t
       
    61 BitMap::inverted_bit_mask_for_range(idx_t beg, idx_t end) const {
       
    62   assert(end != 0, "does not work when end == 0");
       
    63   assert(beg == end || word_index(beg) == word_index(end - 1),
       
    64          "must be a single-word range");
       
    65   idx_t mask = bit_mask(beg) - 1;       // low (right) bits
       
    66   if (bit_in_word(end) != 0) {
       
    67     mask |= ~(bit_mask(end) - 1);       // high (left) bits
       
    68   }
       
    69   return mask;
       
    70 }
       
    71 
       
    72 void BitMap::set_range_within_word(idx_t beg, idx_t end) {
       
    73   // With a valid range (beg <= end), this test ensures that end != 0, as
       
    74   // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.
       
    75   if (beg != end) {
       
    76     idx_t mask = inverted_bit_mask_for_range(beg, end);
       
    77     *word_addr(beg) |= ~mask;
       
    78   }
       
    79 }
       
    80 
       
    81 void BitMap::clear_range_within_word(idx_t beg, idx_t end) {
       
    82   // With a valid range (beg <= end), this test ensures that end != 0, as
       
    83   // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.
       
    84   if (beg != end) {
       
    85     idx_t mask = inverted_bit_mask_for_range(beg, end);
       
    86     *word_addr(beg) &= mask;
       
    87   }
       
    88 }
       
    89 
       
    90 void BitMap::par_put_range_within_word(idx_t beg, idx_t end, bool value) {
       
    91   assert(value == 0 || value == 1, "0 for clear, 1 for set");
       
    92   // With a valid range (beg <= end), this test ensures that end != 0, as
       
    93   // required by inverted_bit_mask_for_range.  Also avoids an unnecessary write.
       
    94   if (beg != end) {
       
    95     intptr_t* pw  = (intptr_t*)word_addr(beg);
       
    96     intptr_t  w   = *pw;
       
    97     intptr_t  mr  = (intptr_t)inverted_bit_mask_for_range(beg, end);
       
    98     intptr_t  nw  = value ? (w | ~mr) : (w & mr);
       
    99     while (true) {
       
   100       intptr_t res = Atomic::cmpxchg_ptr(nw, pw, w);
       
   101       if (res == w) break;
       
   102       w  = *pw;
       
   103       nw = value ? (w | ~mr) : (w & mr);
       
   104     }
       
   105   }
       
   106 }
       
   107 
       
   108 inline void BitMap::set_large_range_of_words(idx_t beg, idx_t end) {
       
   109   memset(_map + beg, ~(unsigned char)0, (end - beg) * sizeof(uintptr_t));
       
   110 }
       
   111 
       
   112 inline void BitMap::clear_large_range_of_words(idx_t beg, idx_t end) {
       
   113   memset(_map + beg, 0, (end - beg) * sizeof(uintptr_t));
       
   114 }
       
   115 
       
   116 inline BitMap::idx_t BitMap::word_index_round_up(idx_t bit) const {
       
   117   idx_t bit_rounded_up = bit + (BitsPerWord - 1);
       
   118   // Check for integer arithmetic overflow.
       
   119   return bit_rounded_up > bit ? word_index(bit_rounded_up) : size_in_words();
       
   120 }
       
   121 
       
   122 void BitMap::set_range(idx_t beg, idx_t end) {
       
   123   verify_range(beg, end);
       
   124 
       
   125   idx_t beg_full_word = word_index_round_up(beg);
       
   126   idx_t end_full_word = word_index(end);
       
   127 
       
   128   if (beg_full_word < end_full_word) {
       
   129     // The range includes at least one full word.
       
   130     set_range_within_word(beg, bit_index(beg_full_word));
       
   131     set_range_of_words(beg_full_word, end_full_word);
       
   132     set_range_within_word(bit_index(end_full_word), end);
       
   133   } else {
       
   134     // The range spans at most 2 partial words.
       
   135     idx_t boundary = MIN2(bit_index(beg_full_word), end);
       
   136     set_range_within_word(beg, boundary);
       
   137     set_range_within_word(boundary, end);
       
   138   }
       
   139 }
       
   140 
       
   141 void BitMap::clear_range(idx_t beg, idx_t end) {
       
   142   verify_range(beg, end);
       
   143 
       
   144   idx_t beg_full_word = word_index_round_up(beg);
       
   145   idx_t end_full_word = word_index(end);
       
   146 
       
   147   if (beg_full_word < end_full_word) {
       
   148     // The range includes at least one full word.
       
   149     clear_range_within_word(beg, bit_index(beg_full_word));
       
   150     clear_range_of_words(beg_full_word, end_full_word);
       
   151     clear_range_within_word(bit_index(end_full_word), end);
       
   152   } else {
       
   153     // The range spans at most 2 partial words.
       
   154     idx_t boundary = MIN2(bit_index(beg_full_word), end);
       
   155     clear_range_within_word(beg, boundary);
       
   156     clear_range_within_word(boundary, end);
       
   157   }
       
   158 }
       
   159 
       
   160 void BitMap::set_large_range(idx_t beg, idx_t end) {
       
   161   verify_range(beg, end);
       
   162 
       
   163   idx_t beg_full_word = word_index_round_up(beg);
       
   164   idx_t end_full_word = word_index(end);
       
   165 
       
   166   assert(end_full_word - beg_full_word >= 32,
       
   167          "the range must include at least 32 bytes");
       
   168 
       
   169   // The range includes at least one full word.
       
   170   set_range_within_word(beg, bit_index(beg_full_word));
       
   171   set_large_range_of_words(beg_full_word, end_full_word);
       
   172   set_range_within_word(bit_index(end_full_word), end);
       
   173 }
       
   174 
       
   175 void BitMap::clear_large_range(idx_t beg, idx_t end) {
       
   176   verify_range(beg, end);
       
   177 
       
   178   idx_t beg_full_word = word_index_round_up(beg);
       
   179   idx_t end_full_word = word_index(end);
       
   180 
       
   181   assert(end_full_word - beg_full_word >= 32,
       
   182          "the range must include at least 32 bytes");
       
   183 
       
   184   // The range includes at least one full word.
       
   185   clear_range_within_word(beg, bit_index(beg_full_word));
       
   186   clear_large_range_of_words(beg_full_word, end_full_word);
       
   187   clear_range_within_word(bit_index(end_full_word), end);
       
   188 }
       
   189 
       
   190 void BitMap::at_put(idx_t offset, bool value) {
       
   191   if (value) {
       
   192     set_bit(offset);
       
   193   } else {
       
   194     clear_bit(offset);
       
   195   }
       
   196 }
       
   197 
       
   198 // Return true to indicate that this thread changed
       
   199 // the bit, false to indicate that someone else did.
       
   200 // In either case, the requested bit is in the
       
   201 // requested state some time during the period that
       
   202 // this thread is executing this call. More importantly,
       
   203 // if no other thread is executing an action to
       
   204 // change the requested bit to a state other than
       
   205 // the one that this thread is trying to set it to,
       
   206 // then the the bit is in the expected state
       
   207 // at exit from this method. However, rather than
       
   208 // make such a strong assertion here, based on
       
   209 // assuming such constrained use (which though true
       
   210 // today, could change in the future to service some
       
   211 // funky parallel algorithm), we encourage callers
       
   212 // to do such verification, as and when appropriate.
       
   213 bool BitMap::par_at_put(idx_t bit, bool value) {
       
   214   return value ? par_set_bit(bit) : par_clear_bit(bit);
       
   215 }
       
   216 
       
   217 void BitMap::at_put_grow(idx_t offset, bool value) {
       
   218   if (offset >= size()) {
       
   219     resize(2 * MAX2(size(), offset));
       
   220   }
       
   221   at_put(offset, value);
       
   222 }
       
   223 
       
   224 void BitMap::at_put_range(idx_t start_offset, idx_t end_offset, bool value) {
       
   225   if (value) {
       
   226     set_range(start_offset, end_offset);
       
   227   } else {
       
   228     clear_range(start_offset, end_offset);
       
   229   }
       
   230 }
       
   231 
       
   232 void BitMap::par_at_put_range(idx_t beg, idx_t end, bool value) {
       
   233   verify_range(beg, end);
       
   234 
       
   235   idx_t beg_full_word = word_index_round_up(beg);
       
   236   idx_t end_full_word = word_index(end);
       
   237 
       
   238   if (beg_full_word < end_full_word) {
       
   239     // The range includes at least one full word.
       
   240     par_put_range_within_word(beg, bit_index(beg_full_word), value);
       
   241     if (value) {
       
   242       set_range_of_words(beg_full_word, end_full_word);
       
   243     } else {
       
   244       clear_range_of_words(beg_full_word, end_full_word);
       
   245     }
       
   246     par_put_range_within_word(bit_index(end_full_word), end, value);
       
   247   } else {
       
   248     // The range spans at most 2 partial words.
       
   249     idx_t boundary = MIN2(bit_index(beg_full_word), end);
       
   250     par_put_range_within_word(beg, boundary, value);
       
   251     par_put_range_within_word(boundary, end, value);
       
   252   }
       
   253 
       
   254 }
       
   255 
       
   256 void BitMap::at_put_large_range(idx_t beg, idx_t end, bool value) {
       
   257   if (value) {
       
   258     set_large_range(beg, end);
       
   259   } else {
       
   260     clear_large_range(beg, end);
       
   261   }
       
   262 }
       
   263 
       
   264 void BitMap::par_at_put_large_range(idx_t beg, idx_t end, bool value) {
       
   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   par_put_range_within_word(beg, bit_index(beg_full_word), value);
       
   275   if (value) {
       
   276     set_large_range_of_words(beg_full_word, end_full_word);
       
   277   } else {
       
   278     clear_large_range_of_words(beg_full_word, end_full_word);
       
   279   }
       
   280   par_put_range_within_word(bit_index(end_full_word), end, value);
       
   281 }
       
   282 
       
   283 bool BitMap::contains(const BitMap other) const {
       
   284   assert(size() == other.size(), "must have same size");
       
   285   uintptr_t* dest_map = map();
       
   286   uintptr_t* other_map = other.map();
       
   287   idx_t size = size_in_words();
       
   288   for (idx_t index = 0; index < size_in_words(); index++) {
       
   289     uintptr_t word_union = dest_map[index] | other_map[index];
       
   290     // If this has more bits set than dest_map[index], then other is not a
       
   291     // subset.
       
   292     if (word_union != dest_map[index]) return false;
       
   293   }
       
   294   return true;
       
   295 }
       
   296 
       
   297 bool BitMap::intersects(const BitMap other) const {
       
   298   assert(size() == other.size(), "must have same size");
       
   299   uintptr_t* dest_map = map();
       
   300   uintptr_t* other_map = other.map();
       
   301   idx_t size = size_in_words();
       
   302   for (idx_t index = 0; index < size_in_words(); index++) {
       
   303     if ((dest_map[index] & other_map[index]) != 0) return true;
       
   304   }
       
   305   // Otherwise, no intersection.
       
   306   return false;
       
   307 }
       
   308 
       
   309 void BitMap::set_union(BitMap other) {
       
   310   assert(size() == other.size(), "must have same size");
       
   311   idx_t* dest_map = map();
       
   312   idx_t* other_map = other.map();
       
   313   idx_t size = size_in_words();
       
   314   for (idx_t index = 0; index < size_in_words(); index++) {
       
   315     dest_map[index] = dest_map[index] | other_map[index];
       
   316   }
       
   317 }
       
   318 
       
   319 
       
   320 void BitMap::set_difference(BitMap other) {
       
   321   assert(size() == other.size(), "must have same size");
       
   322   idx_t* dest_map = map();
       
   323   idx_t* other_map = other.map();
       
   324   idx_t size = size_in_words();
       
   325   for (idx_t index = 0; index < size_in_words(); index++) {
       
   326     dest_map[index] = dest_map[index] & ~(other_map[index]);
       
   327   }
       
   328 }
       
   329 
       
   330 
       
   331 void BitMap::set_intersection(BitMap other) {
       
   332   assert(size() == other.size(), "must have same size");
       
   333   idx_t* dest_map = map();
       
   334   idx_t* other_map = other.map();
       
   335   idx_t size = size_in_words();
       
   336   for (idx_t index = 0; index < size; index++) {
       
   337     dest_map[index]  = dest_map[index] & other_map[index];
       
   338   }
       
   339 }
       
   340 
       
   341 
       
   342 bool BitMap::set_union_with_result(BitMap other) {
       
   343   assert(size() == other.size(), "must have same size");
       
   344   bool changed = false;
       
   345   idx_t* dest_map = map();
       
   346   idx_t* other_map = other.map();
       
   347   idx_t size = size_in_words();
       
   348   for (idx_t index = 0; index < size; index++) {
       
   349     idx_t temp = map(index) | other_map[index];
       
   350     changed = changed || (temp != map(index));
       
   351     map()[index] = temp;
       
   352   }
       
   353   return changed;
       
   354 }
       
   355 
       
   356 
       
   357 bool BitMap::set_difference_with_result(BitMap other) {
       
   358   assert(size() == other.size(), "must have same size");
       
   359   bool changed = false;
       
   360   idx_t* dest_map = map();
       
   361   idx_t* other_map = other.map();
       
   362   idx_t size = size_in_words();
       
   363   for (idx_t index = 0; index < size; index++) {
       
   364     idx_t temp = dest_map[index] & ~(other_map[index]);
       
   365     changed = changed || (temp != dest_map[index]);
       
   366     dest_map[index] = temp;
       
   367   }
       
   368   return changed;
       
   369 }
       
   370 
       
   371 
       
   372 bool BitMap::set_intersection_with_result(BitMap other) {
       
   373   assert(size() == other.size(), "must have same size");
       
   374   bool changed = false;
       
   375   idx_t* dest_map = map();
       
   376   idx_t* other_map = other.map();
       
   377   idx_t size = size_in_words();
       
   378   for (idx_t index = 0; index < size; index++) {
       
   379     idx_t orig = dest_map[index];
       
   380     idx_t temp = orig & other_map[index];
       
   381     changed = changed || (temp != orig);
       
   382     dest_map[index]  = temp;
       
   383   }
       
   384   return changed;
       
   385 }
       
   386 
       
   387 
       
   388 void BitMap::set_from(BitMap other) {
       
   389   assert(size() == other.size(), "must have same size");
       
   390   idx_t* dest_map = map();
       
   391   idx_t* other_map = other.map();
       
   392   idx_t size = size_in_words();
       
   393   for (idx_t index = 0; index < size; index++) {
       
   394     dest_map[index] = other_map[index];
       
   395   }
       
   396 }
       
   397 
       
   398 
       
   399 bool BitMap::is_same(BitMap other) {
       
   400   assert(size() == other.size(), "must have same size");
       
   401   idx_t* dest_map = map();
       
   402   idx_t* other_map = other.map();
       
   403   idx_t size = size_in_words();
       
   404   for (idx_t index = 0; index < size; index++) {
       
   405     if (dest_map[index] != other_map[index]) return false;
       
   406   }
       
   407   return true;
       
   408 }
       
   409 
       
   410 bool BitMap::is_full() const {
       
   411   uintptr_t* word = map();
       
   412   idx_t rest = size();
       
   413   for (; rest >= (idx_t) BitsPerWord; rest -= BitsPerWord) {
       
   414     if (*word != (uintptr_t) AllBits) return false;
       
   415     word++;
       
   416   }
       
   417   return rest == 0 || (*word | ~right_n_bits((int)rest)) == (uintptr_t) AllBits;
       
   418 }
       
   419 
       
   420 
       
   421 bool BitMap::is_empty() const {
       
   422   uintptr_t* word = map();
       
   423   idx_t rest = size();
       
   424   for (; rest >= (idx_t) BitsPerWord; rest -= BitsPerWord) {
       
   425     if (*word != (uintptr_t) NoBits) return false;
       
   426     word++;
       
   427   }
       
   428   return rest == 0 || (*word & right_n_bits((int)rest)) == (uintptr_t) NoBits;
       
   429 }
       
   430 
       
   431 void BitMap::clear_large() {
       
   432   clear_large_range_of_words(0, size_in_words());
       
   433 }
       
   434 
       
   435 // Note that if the closure itself modifies the bitmap
       
   436 // then modifications in and to the left of the _bit_ being
       
   437 // currently sampled will not be seen. Note also that the
       
   438 // interval [leftOffset, rightOffset) is right open.
       
   439 void BitMap::iterate(BitMapClosure* blk, idx_t leftOffset, idx_t rightOffset) {
       
   440   verify_range(leftOffset, rightOffset);
       
   441 
       
   442   idx_t startIndex = word_index(leftOffset);
       
   443   idx_t endIndex   = MIN2(word_index(rightOffset) + 1, size_in_words());
       
   444   for (idx_t index = startIndex, offset = leftOffset;
       
   445        offset < rightOffset && index < endIndex;
       
   446        offset = (++index) << LogBitsPerWord) {
       
   447     idx_t rest = map(index) >> (offset & (BitsPerWord - 1));
       
   448     for (; offset < rightOffset && rest != (uintptr_t)NoBits; offset++) {
       
   449       if (rest & 1) {
       
   450         blk->do_bit(offset);
       
   451         //  resample at each closure application
       
   452         // (see, for instance, CMS bug 4525989)
       
   453         rest = map(index) >> (offset & (BitsPerWord -1));
       
   454         // XXX debugging: remove
       
   455         // The following assertion assumes that closure application
       
   456         // doesn't clear bits (may not be true in general, e.g. G1).
       
   457         assert(rest & 1,
       
   458                "incorrect shift or closure application can clear bits?");
       
   459       }
       
   460       rest = rest >> 1;
       
   461     }
       
   462   }
       
   463 }
       
   464 
       
   465 BitMap::idx_t BitMap::get_next_one_offset(idx_t l_offset,
       
   466                                           idx_t r_offset) const {
       
   467   assert(l_offset <= size(), "BitMap index out of bounds");
       
   468   assert(r_offset <= size(), "BitMap index out of bounds");
       
   469   assert(l_offset <= r_offset, "l_offset > r_offset ?");
       
   470 
       
   471   if (l_offset == r_offset) {
       
   472     return l_offset;
       
   473   }
       
   474   idx_t   index = word_index(l_offset);
       
   475   idx_t r_index = word_index(r_offset-1) + 1;
       
   476   idx_t res_offset = l_offset;
       
   477 
       
   478   // check bits including and to the _left_ of offset's position
       
   479   idx_t pos = bit_in_word(res_offset);
       
   480   idx_t res = map(index) >> pos;
       
   481   if (res != (uintptr_t)NoBits) {
       
   482     // find the position of the 1-bit
       
   483     for (; !(res & 1); res_offset++) {
       
   484       res = res >> 1;
       
   485     }
       
   486     assert(res_offset >= l_offset, "just checking");
       
   487     return MIN2(res_offset, r_offset);
       
   488   }
       
   489   // skip over all word length 0-bit runs
       
   490   for (index++; index < r_index; index++) {
       
   491     res = map(index);
       
   492     if (res != (uintptr_t)NoBits) {
       
   493       // found a 1, return the offset
       
   494       for (res_offset = index << LogBitsPerWord; !(res & 1);
       
   495            res_offset++) {
       
   496         res = res >> 1;
       
   497       }
       
   498       assert(res & 1, "tautology; see loop condition");
       
   499       assert(res_offset >= l_offset, "just checking");
       
   500       return MIN2(res_offset, r_offset);
       
   501     }
       
   502   }
       
   503   return r_offset;
       
   504 }
       
   505 
       
   506 BitMap::idx_t BitMap::get_next_zero_offset(idx_t l_offset,
       
   507                                            idx_t r_offset) const {
       
   508   assert(l_offset <= size(), "BitMap index out of bounds");
       
   509   assert(r_offset <= size(), "BitMap index out of bounds");
       
   510   assert(l_offset <= r_offset, "l_offset > r_offset ?");
       
   511 
       
   512   if (l_offset == r_offset) {
       
   513     return l_offset;
       
   514   }
       
   515   idx_t   index = word_index(l_offset);
       
   516   idx_t r_index = word_index(r_offset-1) + 1;
       
   517   idx_t res_offset = l_offset;
       
   518 
       
   519   // check bits including and to the _left_ of offset's position
       
   520   idx_t pos = res_offset & (BitsPerWord - 1);
       
   521   idx_t res = (map(index) >> pos) | left_n_bits((int)pos);
       
   522 
       
   523   if (res != (uintptr_t)AllBits) {
       
   524     // find the position of the 0-bit
       
   525     for (; res & 1; res_offset++) {
       
   526       res = res >> 1;
       
   527     }
       
   528     assert(res_offset >= l_offset, "just checking");
       
   529     return MIN2(res_offset, r_offset);
       
   530   }
       
   531   // skip over all word length 1-bit runs
       
   532   for (index++; index < r_index; index++) {
       
   533     res = map(index);
       
   534     if (res != (uintptr_t)AllBits) {
       
   535       // found a 0, return the offset
       
   536       for (res_offset = index << LogBitsPerWord; res & 1;
       
   537            res_offset++) {
       
   538         res = res >> 1;
       
   539       }
       
   540       assert(!(res & 1), "tautology; see loop condition");
       
   541       assert(res_offset >= l_offset, "just checking");
       
   542       return MIN2(res_offset, r_offset);
       
   543     }
       
   544   }
       
   545   return r_offset;
       
   546 }
       
   547 
       
   548 #ifndef PRODUCT
       
   549 
       
   550 void BitMap::print_on(outputStream* st) const {
       
   551   tty->print("Bitmap(%d):", size());
       
   552   for (idx_t index = 0; index < size(); index++) {
       
   553     tty->print("%c", at(index) ? '1' : '0');
       
   554   }
       
   555   tty->cr();
       
   556 }
       
   557 
       
   558 #endif
       
   559 
       
   560 
       
   561 BitMap2D::BitMap2D(uintptr_t* map, idx_t size_in_slots, idx_t bits_per_slot)
       
   562   : _bits_per_slot(bits_per_slot)
       
   563   , _map(map, size_in_slots * bits_per_slot)
       
   564 {
       
   565 }
       
   566 
       
   567 
       
   568 BitMap2D::BitMap2D(idx_t size_in_slots, idx_t bits_per_slot)
       
   569   : _bits_per_slot(bits_per_slot)
       
   570   , _map(size_in_slots * bits_per_slot)
       
   571 {
       
   572 }