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 /*

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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * This code is free software; you can redistribute it and/or modify it

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  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 #ifndef SHARE_VM_UTILITIES_BITMAP_HPP

 #define SHARE_VM_UTILITIES_BITMAP_HPP

 #include "memory/allocation.hpp"

 #include "utilities/top.hpp"

 // Forward decl;

 class BitMapClosure;

 // Operations for bitmaps represented as arrays of unsigned integers.

 // Bit offsets are numbered from 0 to size-1.

 class BitMap VALUE_OBJ_CLASS_SPEC {

   friend class BitMap2D;

  public:

   typedef size_t idx_t;         // Type used for bit and word indices.

   typedef uintptr_t bm_word_t;  // Element type of array that represents

                                 // the bitmap.

   // Hints for range sizes.

   typedef enum {

     unknown_range, small_range, large_range

   } RangeSizeHint;

  private:

   bm_word_t* _map;     // First word in bitmap

   idx_t      _size;    // Size of bitmap (in bits)

   // Puts the given value at the given offset, using resize() to size

   // the bitmap appropriately if needed using factor-of-two expansion.

   void at_put_grow(idx_t index, bool value);

  protected:

   // Return the position of bit within the word that contains it (e.g., if

   // bitmap words are 32 bits, return a number 0 <= n <= 31).

   static idx_t bit_in_word(idx_t bit) { return bit & (BitsPerWord - 1); }

   // Return a mask that will select the specified bit, when applied to the word

   // containing the bit.

   static bm_word_t bit_mask(idx_t bit) { return (bm_word_t)1 << bit_in_word(bit); }

   // Return the index of the word containing the specified bit.

   static idx_t word_index(idx_t bit)  { return bit >> LogBitsPerWord; }

   // Return the bit number of the first bit in the specified word.

   static idx_t bit_index(idx_t word)  { return word << LogBitsPerWord; }

   // Return the array of bitmap words, or a specific word from it.

   bm_word_t* map() const           { return _map; }

   bm_word_t  map(idx_t word) const { return _map[word]; }

   // Return a pointer to the word containing the specified bit.

   bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); }

   // Set a word to a specified value or to all ones; clear a word.

   void set_word  (idx_t word, bm_word_t val) { _map[word] = val; }

   void set_word  (idx_t word)            { set_word(word, ~(uintptr_t)0); }

   void clear_word(idx_t word)            { _map[word] = 0; }

   // Utilities for ranges of bits.  Ranges are half-open [beg, end).

   // Ranges within a single word.

   bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const;

   void  set_range_within_word      (idx_t beg, idx_t end);

   void  clear_range_within_word    (idx_t beg, idx_t end);

   void  par_put_range_within_word  (idx_t beg, idx_t end, bool value);

   // Ranges spanning entire words.

   void      set_range_of_words         (idx_t beg, idx_t end);

   void      clear_range_of_words       (idx_t beg, idx_t end);

   void      set_large_range_of_words   (idx_t beg, idx_t end);

   void      clear_large_range_of_words (idx_t beg, idx_t end);

   // The index of the first full word in a range.

   idx_t word_index_round_up(idx_t bit) const;

   // Verification.

   inline void verify_index(idx_t index) const NOT_DEBUG_RETURN;

   inline void verify_range(idx_t beg_index, idx_t end_index) const

     NOT_DEBUG_RETURN;

   // Statistics.

   static idx_t* _pop_count_table;

   static void init_pop_count_table();

   static idx_t num_set_bits(bm_word_t w);

   static idx_t num_set_bits_from_table(unsigned char c);

  public:

   // Constructs a bitmap with no map, and size 0.

   BitMap() : _map(NULL), _size(0) {}

   // Constructs a bitmap with the given map and size.

   BitMap(bm_word_t* map, idx_t size_in_bits);

   // Constructs an empty bitmap of the given size (that is, this clears the

   // new bitmap).  Allocates the map array in resource area if

   // "in_resource_area" is true, else in the C heap.

   BitMap(idx_t size_in_bits, bool in_resource_area = true);

   // Set the map and size.

   void set_map(bm_word_t* map)      { _map = map; }

   void set_size(idx_t size_in_bits) { _size = size_in_bits; }

   // Allocates necessary data structure, either in the resource area

   // or in the C heap, as indicated by "in_resource_area."

   // Preserves state currently in bit map by copying data.

   // Zeros any newly-addressable bits.

   // If "in_resource_area" is false, frees the current map.

   // (Note that this assumes that all calls to "resize" on the same BitMap

   // use the same value for "in_resource_area".)

   void resize(idx_t size_in_bits, bool in_resource_area = true);

   // Accessing

   idx_t size() const                    { return _size; }

   idx_t size_in_words() const           {

     return word_index(size() + BitsPerWord - 1);

   }

   bool at(idx_t index) const {

     verify_index(index);

     return (*word_addr(index) & bit_mask(index)) != 0;

   }

   // Align bit index up or down to the next bitmap word boundary, or check

   // alignment.

   static idx_t word_align_up(idx_t bit) {

     return align_size_up(bit, BitsPerWord);

   }

   static idx_t word_align_down(idx_t bit) {

     return align_size_down(bit, BitsPerWord);

   }

   static bool is_word_aligned(idx_t bit) {

     return word_align_up(bit) == bit;

   }

   // Set or clear the specified bit.

   inline void set_bit(idx_t bit);

   void clear_bit(idx_t bit);

   // Atomically set or clear the specified bit.

   bool par_set_bit(idx_t bit);

   bool par_clear_bit(idx_t bit);

   // Put the given value at the given offset. The parallel version

   // will CAS the value into the bitmap and is quite a bit slower.

   // The parallel version also returns a value indicating if the

   // calling thread was the one that changed the value of the bit.

   void at_put(idx_t index, bool value);

   bool par_at_put(idx_t index, bool value);

   // Update a range of bits.  Ranges are half-open [beg, end).

   void set_range   (idx_t beg, idx_t end);

   void clear_range (idx_t beg, idx_t end);

   void set_large_range   (idx_t beg, idx_t end);

   void clear_large_range (idx_t beg, idx_t end);

   void at_put_range(idx_t beg, idx_t end, bool value);

   void par_at_put_range(idx_t beg, idx_t end, bool value);

   void at_put_large_range(idx_t beg, idx_t end, bool value);

   void par_at_put_large_range(idx_t beg, idx_t end, bool value);

   // Update a range of bits, using a hint about the size.  Currently only

   // inlines the predominant case of a 1-bit range.  Works best when hint is a

   // compile-time constant.

   void set_range(idx_t beg, idx_t end, RangeSizeHint hint);

   void clear_range(idx_t beg, idx_t end, RangeSizeHint hint);

   void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint);

   void par_clear_range  (idx_t beg, idx_t end, RangeSizeHint hint);

   // It performs the union operation between subsets of equal length

   // of two bitmaps (the target bitmap of the method and the

   // from_bitmap) and stores the result to the target bitmap.  The

   // from_start_index represents the first bit index of the subrange

   // of the from_bitmap.  The to_start_index is the equivalent of the

   // target bitmap. Both indexes should be word-aligned, i.e. they

   // should correspond to the first bit on a bitmap word (it's up to

   // the caller to ensure this; the method does check it).  The length

   // of the subset is specified with word_num and it is in number of

   // bitmap words. The caller should ensure that this is at least 2

   // (smaller ranges are not support to save extra checks).  Again,

   // this is checked in the method.

   //

   // Atomicity concerns: it is assumed that any contention on the

   // target bitmap with other threads will happen on the first and

   // last words; the ones in between will be "owned" exclusively by

   // the calling thread and, in fact, they will already be 0. So, the

   // method performs a CAS on the first word, copies the next

   // word_num-2 words, and finally performs a CAS on the last word.

   void mostly_disjoint_range_union(BitMap* from_bitmap,

                                    idx_t   from_start_index,

                                    idx_t   to_start_index,

                                    size_t  word_num);

   // Clearing

   void clear_large();

   inline void clear();

   // Iteration support.  Returns "true" if the iteration completed, false

   // if the iteration terminated early (because the closure "blk" returned

   // false).

   bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex);

   bool iterate(BitMapClosure* blk) {

     // call the version that takes an interval

     return iterate(blk, 0, size());

   }

   // Looking for 1's and 0's at indices equal to or greater than "l_index",

   // stopping if none has been found before "r_index", and returning

   // "r_index" (which must be at most "size") in that case.

   idx_t get_next_one_offset_inline (idx_t l_index, idx_t r_index) const;

   idx_t get_next_zero_offset_inline(idx_t l_index, idx_t r_index) const;

   // Like "get_next_one_offset_inline", except requires that "r_index" is

   // aligned to bitsizeof(bm_word_t).

   idx_t get_next_one_offset_inline_aligned_right(idx_t l_index,

                                                         idx_t r_index) const;

   // Non-inline versionsof the above.

   idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const;

   idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const;

   idx_t get_next_one_offset(idx_t offset) const {

     return get_next_one_offset(offset, size());

   }

   idx_t get_next_zero_offset(idx_t offset) const {

     return get_next_zero_offset(offset, size());

   }

   // Returns the number of bits set in the bitmap.

   idx_t count_one_bits() const;

   // Set operations.

   void set_union(BitMap bits);

   void set_difference(BitMap bits);

   void set_intersection(BitMap bits);

   // Returns true iff "this" is a superset of "bits".

   bool contains(const BitMap bits) const;

   // Returns true iff "this and "bits" have a non-empty intersection.

   bool intersects(const BitMap bits) const;

   // Returns result of whether this map changed

   // during the operation

   bool set_union_with_result(BitMap bits);

   bool set_difference_with_result(BitMap bits);

   bool set_intersection_with_result(BitMap bits);

   // Requires the submap of "bits" starting at offset to be at least as

   // large as "this".  Modifies "this" to be the intersection of its

   // current contents and the submap of "bits" starting at "offset" of the

   // same length as "this."

   // (For expedience, currently requires the offset to be aligned to the

   // bitsize of a uintptr_t.  This should go away in the future though it

   // will probably remain a good case to optimize.)

   void set_intersection_at_offset(BitMap bits, idx_t offset);

   void set_from(BitMap bits);

   bool is_same(BitMap bits);

   // Test if all bits are set or cleared

   bool is_full() const;

   bool is_empty() const;

 #ifndef PRODUCT

  public:

   // Printing

   void print_on(outputStream* st) const;

 #endif

 };

 // Convenience class wrapping BitMap which provides multiple bits per slot.

 class BitMap2D VALUE_OBJ_CLASS_SPEC {

  public:

   typedef BitMap::idx_t idx_t;          // Type used for bit and word indices.

   typedef BitMap::bm_word_t bm_word_t;  // Element type of array that

                                         // represents the bitmap.

  private:

   BitMap _map;

   idx_t  _bits_per_slot;

   idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const {

     return slot_index * _bits_per_slot + bit_within_slot_index;

   }

   void verify_bit_within_slot_index(idx_t index) const {

     assert(index < _bits_per_slot, "bit_within_slot index out of bounds");

   }

  public:

   // Construction. bits_per_slot must be greater than 0.

   BitMap2D(bm_word_t* map, idx_t size_in_slots, idx_t bits_per_slot);

   // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0.

   BitMap2D(idx_t size_in_slots, idx_t bits_per_slot);

   idx_t size_in_bits() {

     return _map.size();

   }

   // Returns number of full slots that have been allocated

   idx_t size_in_slots() {

     // Round down

     return _map.size() / _bits_per_slot;

   }

   bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index) {

     verify_bit_within_slot_index(bit_within_slot_index);

     return (bit_index(slot_index, bit_within_slot_index) < size_in_bits());

   }

   bool at(idx_t slot_index, idx_t bit_within_slot_index) const {

     verify_bit_within_slot_index(bit_within_slot_index);

     return _map.at(bit_index(slot_index, bit_within_slot_index));

   }

   void set_bit(idx_t slot_index, idx_t bit_within_slot_index) {

     verify_bit_within_slot_index(bit_within_slot_index);

     _map.set_bit(bit_index(slot_index, bit_within_slot_index));

   }

   void clear_bit(idx_t slot_index, idx_t bit_within_slot_index) {

     verify_bit_within_slot_index(bit_within_slot_index);

     _map.clear_bit(bit_index(slot_index, bit_within_slot_index));

   }

   void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value) {

     verify_bit_within_slot_index(bit_within_slot_index);

     _map.at_put(bit_index(slot_index, bit_within_slot_index), value);

   }

   void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value) {

     verify_bit_within_slot_index(bit_within_slot_index);

     _map.at_put_grow(bit_index(slot_index, bit_within_slot_index), value);

   }

   void clear();

 };

 // Closure for iterating over BitMaps

 class BitMapClosure VALUE_OBJ_CLASS_SPEC {

  public:

   // Callback when bit in map is set.  Should normally return "true";

   // return of false indicates that the bitmap iteration should terminate.

   virtual bool do_bit(BitMap::idx_t offset) = 0;

 };

 #endif // SHARE_VM_UTILITIES_BITMAP_HPP