1 /*
   2  * Copyright (c) 2005, 2013, 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_VM_UTILITIES_BITMAP_INLINE_HPP
  26 #define SHARE_VM_UTILITIES_BITMAP_INLINE_HPP
  27 
  28 #include "runtime/atomic.inline.hpp"
  29 #include "utilities/bitMap.hpp"
  30 
  31 #ifdef ASSERT
  32 inline void BitMap::verify_index(idx_t index) const {
  33   assert(index < _size, "BitMap index out of bounds");
  34 }
  35 
  36 inline void BitMap::verify_range(idx_t beg_index, idx_t end_index) const {
  37   assert(beg_index <= end_index, "BitMap range error");
  38   // Note that [0,0) and [size,size) are both valid ranges.
  39   if (end_index != _size) verify_index(end_index);
  40 }
  41 #endif // #ifdef ASSERT
  42 
  43 inline void BitMap::set_bit(idx_t bit) {
  44   verify_index(bit);
  45   *word_addr(bit) |= bit_mask(bit);
  46 }
  47 
  48 inline void BitMap::clear_bit(idx_t bit) {
  49   verify_index(bit);
  50   *word_addr(bit) &= ~bit_mask(bit);
  51 }
  52 
  53 inline bool BitMap::par_set_bit(idx_t bit) {
  54   verify_index(bit);
  55   volatile bm_word_t* const addr = word_addr(bit);
  56   const bm_word_t mask = bit_mask(bit);
  57   bm_word_t old_val = *addr;
  58 
  59   do {
  60     const bm_word_t new_val = old_val | mask;
  61     if (new_val == old_val) {
  62       return false;     // Someone else beat us to it.
  63     }
  64     const bm_word_t cur_val = (bm_word_t) Atomic::cmpxchg_ptr((void*) new_val,
  65                                                       (volatile void*) addr,
  66                                                       (void*) old_val);
  67     if (cur_val == old_val) {
  68       return true;      // Success.
  69     }
  70     old_val = cur_val;  // The value changed, try again.
  71   } while (true);
  72 }
  73 
  74 inline bool BitMap::par_clear_bit(idx_t bit) {
  75   verify_index(bit);
  76   volatile bm_word_t* const addr = word_addr(bit);
  77   const bm_word_t mask = ~bit_mask(bit);
  78   bm_word_t old_val = *addr;
  79 
  80   do {
  81     const bm_word_t new_val = old_val & mask;
  82     if (new_val == old_val) {
  83       return false;     // Someone else beat us to it.
  84     }
  85     const bm_word_t cur_val = (bm_word_t) Atomic::cmpxchg_ptr((void*) new_val,
  86                                                       (volatile void*) addr,
  87                                                       (void*) old_val);
  88     if (cur_val == old_val) {
  89       return true;      // Success.
  90     }
  91     old_val = cur_val;  // The value changed, try again.
  92   } while (true);
  93 }
  94 
  95 inline void BitMap::set_range(idx_t beg, idx_t end, RangeSizeHint hint) {
  96   if (hint == small_range && end - beg == 1) {
  97     set_bit(beg);
  98   } else {
  99     if (hint == large_range) {
 100       set_large_range(beg, end);
 101     } else {
 102       set_range(beg, end);
 103     }
 104   }
 105 }
 106 
 107 inline void BitMap::clear_range(idx_t beg, idx_t end, RangeSizeHint hint) {
 108   if (hint == small_range && end - beg == 1) {
 109     clear_bit(beg);
 110   } else {
 111     if (hint == large_range) {
 112       clear_large_range(beg, end);
 113     } else {
 114       clear_range(beg, end);
 115     }
 116   }
 117 }
 118 
 119 inline void BitMap::par_set_range(idx_t beg, idx_t end, RangeSizeHint hint) {
 120   if (hint == small_range && end - beg == 1) {
 121     par_at_put(beg, true);
 122   } else {
 123     if (hint == large_range) {
 124       par_at_put_large_range(beg, end, true);
 125     } else {
 126       par_at_put_range(beg, end, true);
 127     }
 128   }
 129 }
 130 
 131 inline void BitMap::set_range_of_words(idx_t beg, idx_t end) {
 132   bm_word_t* map = _map;
 133   for (idx_t i = beg; i < end; ++i) map[i] = ~(uintptr_t)0;
 134 }
 135 
 136 
 137 inline void BitMap::clear_range_of_words(idx_t beg, idx_t end) {
 138   bm_word_t* map = _map;
 139   for (idx_t i = beg; i < end; ++i) map[i] = 0;
 140 }
 141 
 142 
 143 inline void BitMap::clear() {
 144   clear_range_of_words(0, size_in_words());
 145 }
 146 
 147 
 148 inline void BitMap::par_clear_range(idx_t beg, idx_t end, RangeSizeHint hint) {
 149   if (hint == small_range && end - beg == 1) {
 150     par_at_put(beg, false);
 151   } else {
 152     if (hint == large_range) {
 153       par_at_put_large_range(beg, end, false);
 154     } else {
 155       par_at_put_range(beg, end, false);
 156     }
 157   }
 158 }
 159 
 160 inline BitMap::idx_t
 161 BitMap::get_next_one_offset_inline(idx_t l_offset, idx_t r_offset) const {
 162   assert(l_offset <= size(), "BitMap index out of bounds");
 163   assert(r_offset <= size(), "BitMap index out of bounds");
 164   assert(l_offset <= r_offset, "l_offset > r_offset ?");
 165 
 166   if (l_offset == r_offset) {
 167     return l_offset;
 168   }
 169   idx_t   index = word_index(l_offset);
 170   idx_t r_index = word_index(r_offset-1) + 1;
 171   idx_t res_offset = l_offset;
 172 
 173   // check bits including and to the _left_ of offset's position
 174   idx_t pos = bit_in_word(res_offset);
 175   idx_t res = map(index) >> pos;
 176   if (res != (uintptr_t)NoBits) {
 177     // find the position of the 1-bit
 178     for (; !(res & 1); res_offset++) {
 179       res = res >> 1;
 180     }
 181 
 182 #ifdef ASSERT
 183     // In the following assert, if r_offset is not bitamp word aligned,
 184     // checking that res_offset is strictly less than r_offset is too
 185     // strong and will trip the assert.
 186     //
 187     // Consider the case where l_offset is bit 15 and r_offset is bit 17
 188     // of the same map word, and where bits [15:16:17:18] == [00:00:00:01].
 189     // All the bits in the range [l_offset:r_offset) are 0.
 190     // The loop that calculates res_offset, above, would yield the offset
 191     // of bit 18 because it's in the same map word as l_offset and there
 192     // is a set bit in that map word above l_offset (i.e. res != NoBits).
 193     //
 194     // In this case, however, we can assert is that res_offset is strictly
 195     // less than size() since we know that there is at least one set bit
 196     // at an offset above, but in the same map word as, r_offset.
 197     // Otherwise, if r_offset is word aligned then it will not be in the
 198     // same map word as l_offset (unless it equals l_offset). So either
 199     // there won't be a set bit between l_offset and the end of it's map
 200     // word (i.e. res == NoBits), or res_offset will be less than r_offset.
 201 
 202     idx_t limit = is_word_aligned(r_offset) ? r_offset : size();
 203     assert(res_offset >= l_offset && res_offset < limit, "just checking");
 204 #endif // ASSERT
 205     return MIN2(res_offset, r_offset);
 206   }
 207   // skip over all word length 0-bit runs
 208   for (index++; index < r_index; index++) {
 209     res = map(index);
 210     if (res != (uintptr_t)NoBits) {
 211       // found a 1, return the offset
 212       for (res_offset = bit_index(index); !(res & 1); res_offset++) {
 213         res = res >> 1;
 214       }
 215       assert(res & 1, "tautology; see loop condition");
 216       assert(res_offset >= l_offset, "just checking");
 217       return MIN2(res_offset, r_offset);
 218     }
 219   }
 220   return r_offset;
 221 }
 222 
 223 inline BitMap::idx_t
 224 BitMap::get_next_zero_offset_inline(idx_t l_offset, idx_t r_offset) const {
 225   assert(l_offset <= size(), "BitMap index out of bounds");
 226   assert(r_offset <= size(), "BitMap index out of bounds");
 227   assert(l_offset <= r_offset, "l_offset > r_offset ?");
 228 
 229   if (l_offset == r_offset) {
 230     return l_offset;
 231   }
 232   idx_t   index = word_index(l_offset);
 233   idx_t r_index = word_index(r_offset-1) + 1;
 234   idx_t res_offset = l_offset;
 235 
 236   // check bits including and to the _left_ of offset's position
 237   idx_t pos = res_offset & (BitsPerWord - 1);
 238   idx_t res = (map(index) >> pos) | left_n_bits((int)pos);
 239 
 240   if (res != (uintptr_t)AllBits) {
 241     // find the position of the 0-bit
 242     for (; res & 1; res_offset++) {
 243       res = res >> 1;
 244     }
 245     assert(res_offset >= l_offset, "just checking");
 246     return MIN2(res_offset, r_offset);
 247   }
 248   // skip over all word length 1-bit runs
 249   for (index++; index < r_index; index++) {
 250     res = map(index);
 251     if (res != (uintptr_t)AllBits) {
 252       // found a 0, return the offset
 253       for (res_offset = index << LogBitsPerWord; res & 1;
 254            res_offset++) {
 255         res = res >> 1;
 256       }
 257       assert(!(res & 1), "tautology; see loop condition");
 258       assert(res_offset >= l_offset, "just checking");
 259       return MIN2(res_offset, r_offset);
 260     }
 261   }
 262   return r_offset;
 263 }
 264 
 265 inline BitMap::idx_t
 266 BitMap::get_next_one_offset_inline_aligned_right(idx_t l_offset,
 267                                                  idx_t r_offset) const
 268 {
 269   verify_range(l_offset, r_offset);
 270   assert(bit_in_word(r_offset) == 0, "r_offset not word-aligned");
 271 
 272   if (l_offset == r_offset) {
 273     return l_offset;
 274   }
 275   idx_t   index = word_index(l_offset);
 276   idx_t r_index = word_index(r_offset);
 277   idx_t res_offset = l_offset;
 278 
 279   // check bits including and to the _left_ of offset's position
 280   idx_t res = map(index) >> bit_in_word(res_offset);
 281   if (res != (uintptr_t)NoBits) {
 282     // find the position of the 1-bit
 283     for (; !(res & 1); res_offset++) {
 284       res = res >> 1;
 285     }
 286     assert(res_offset >= l_offset &&
 287            res_offset < r_offset, "just checking");
 288     return res_offset;
 289   }
 290   // skip over all word length 0-bit runs
 291   for (index++; index < r_index; index++) {
 292     res = map(index);
 293     if (res != (uintptr_t)NoBits) {
 294       // found a 1, return the offset
 295       for (res_offset = bit_index(index); !(res & 1); res_offset++) {
 296         res = res >> 1;
 297       }
 298       assert(res & 1, "tautology; see loop condition");
 299       assert(res_offset >= l_offset && res_offset < r_offset, "just checking");
 300       return res_offset;
 301     }
 302   }
 303   return r_offset;
 304 }
 305 
 306 
 307 // Returns a bit mask for a range of bits [beg, end) within a single word.  Each
 308 // bit in the mask is 0 if the bit is in the range, 1 if not in the range.  The
 309 // returned mask can be used directly to clear the range, or inverted to set the
 310 // range.  Note:  end must not be 0.
 311 inline BitMap::bm_word_t
 312 BitMap::inverted_bit_mask_for_range(idx_t beg, idx_t end) const {
 313   assert(end != 0, "does not work when end == 0");
 314   assert(beg == end || word_index(beg) == word_index(end - 1),
 315          "must be a single-word range");
 316   bm_word_t mask = bit_mask(beg) - 1;   // low (right) bits
 317   if (bit_in_word(end) != 0) {
 318     mask |= ~(bit_mask(end) - 1);       // high (left) bits
 319   }
 320   return mask;
 321 }
 322 
 323 inline void BitMap::set_large_range_of_words(idx_t beg, idx_t end) {
 324   assert(beg <= end, "underflow");
 325   memset(_map + beg, ~(unsigned char)0, (end - beg) * sizeof(uintptr_t));
 326 }
 327 
 328 inline void BitMap::clear_large_range_of_words(idx_t beg, idx_t end) {
 329   assert(beg <= end, "underflow");
 330   memset(_map + beg, 0, (end - beg) * sizeof(uintptr_t));
 331 }
 332 
 333 inline BitMap::idx_t BitMap::word_index_round_up(idx_t bit) const {
 334   idx_t bit_rounded_up = bit + (BitsPerWord - 1);
 335   // Check for integer arithmetic overflow.
 336   return bit_rounded_up > bit ? word_index(bit_rounded_up) : size_in_words();
 337 }
 338 
 339 inline BitMap::idx_t BitMap::get_next_one_offset(idx_t l_offset,
 340                                           idx_t r_offset) const {
 341   return get_next_one_offset_inline(l_offset, r_offset);
 342 }
 343 
 344 inline BitMap::idx_t BitMap::get_next_zero_offset(idx_t l_offset,
 345                                            idx_t r_offset) const {
 346   return get_next_zero_offset_inline(l_offset, r_offset);
 347 }
 348 
 349 inline void BitMap2D::clear() {
 350   _map.clear();
 351 }
 352 
 353 #endif // SHARE_VM_UTILITIES_BITMAP_INLINE_HPP