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hotspot/src/share/vm/gc_implementation/parallelScavenge/parMarkBitMap.cpp

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+/*
+ * Copyright 2005-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * 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.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_parMarkBitMap.cpp.incl"
+
+bool
+ParMarkBitMap::initialize(MemRegion covered_region)
+{
+  const idx_t bits = bits_required(covered_region);
+  // The bits will be divided evenly between two bitmaps; each of them should be
+  // an integral number of words.
+  assert(bits % (BitsPerWord * 2) == 0, "region size unaligned");
+
+  const size_t words = bits / BitsPerWord;
+  const size_t raw_bytes = words * sizeof(idx_t);
+  const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
+  const size_t granularity = os::vm_allocation_granularity();
+  const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
+
+  const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
+    MAX2(page_sz, granularity);
+  ReservedSpace rs(bytes, rs_align, false);
+  os::trace_page_sizes("par bitmap", raw_bytes, raw_bytes, page_sz,
+                       rs.base(), rs.size());
+  _virtual_space = new PSVirtualSpace(rs, page_sz);
+  if (_virtual_space != NULL && _virtual_space->expand_by(bytes)) {
+    _region_start = covered_region.start();
+    _region_size = covered_region.word_size();
+    idx_t* map = (idx_t*)_virtual_space->reserved_low_addr();
+    _beg_bits.set_map(map);
+    _beg_bits.set_size(bits / 2);
+    _end_bits.set_map(map + words / 2);
+    _end_bits.set_size(bits / 2);
+    return true;
+  }
+
+  _region_start = 0;
+  _region_size = 0;
+  if (_virtual_space != NULL) {
+    delete _virtual_space;
+    _virtual_space = NULL;
+  }
+  return false;
+}
+
+#ifdef ASSERT
+extern size_t mark_bitmap_count;
+extern size_t mark_bitmap_size;
+#endif  // #ifdef ASSERT
+
+bool
+ParMarkBitMap::mark_obj(HeapWord* addr, size_t size)
+{
+  const idx_t beg_bit = addr_to_bit(addr);
+  if (_beg_bits.par_set_bit(beg_bit)) {
+    const idx_t end_bit = addr_to_bit(addr + size - 1);
+    bool end_bit_ok = _end_bits.par_set_bit(end_bit);
+    assert(end_bit_ok, "concurrency problem");
+    DEBUG_ONLY(Atomic::inc_ptr(&mark_bitmap_count));
+    DEBUG_ONLY(Atomic::add_ptr(size, &mark_bitmap_size));
+    return true;
+  }
+  return false;
+}
+
+size_t
+ParMarkBitMap::live_words_in_range(HeapWord* beg_addr, HeapWord* end_addr) const
+{
+  assert(beg_addr <= end_addr, "bad range");
+
+  idx_t live_bits = 0;
+
+  // The bitmap routines require the right boundary to be word-aligned.
+  const idx_t end_bit = addr_to_bit(end_addr);
+  const idx_t range_end = BitMap::word_align_up(end_bit);
+
+  idx_t beg_bit = find_obj_beg(addr_to_bit(beg_addr), range_end);
+  while (beg_bit < end_bit) {
+    idx_t tmp_end = find_obj_end(beg_bit, range_end);
+    if (tmp_end < end_bit) {
+      live_bits += tmp_end - beg_bit + 1;
+      beg_bit = find_obj_beg(tmp_end + 1, range_end);
+    } else {
+      live_bits += end_bit - beg_bit;  // No + 1 here; end_bit is not counted.
+      return bits_to_words(live_bits);
+    }
+  }
+  return bits_to_words(live_bits);
+}
+
+size_t ParMarkBitMap::live_words_in_range(HeapWord* beg_addr, oop end_obj) const
+{
+  assert(beg_addr <= (HeapWord*)end_obj, "bad range");
+  assert(is_marked(end_obj), "end_obj must be live");
+
+  idx_t live_bits = 0;
+
+  // The bitmap routines require the right boundary to be word-aligned.
+  const idx_t end_bit = addr_to_bit((HeapWord*)end_obj);
+  const idx_t range_end = BitMap::word_align_up(end_bit);
+
+  idx_t beg_bit = find_obj_beg(addr_to_bit(beg_addr), range_end);
+  while (beg_bit < end_bit) {
+    idx_t tmp_end = find_obj_end(beg_bit, range_end);
+    assert(tmp_end < end_bit, "missing end bit");
+    live_bits += tmp_end - beg_bit + 1;
+    beg_bit = find_obj_beg(tmp_end + 1, range_end);
+  }
+  return bits_to_words(live_bits);
+}
+
+ParMarkBitMap::IterationStatus
+ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
+                       idx_t range_beg, idx_t range_end) const
+{
+  DEBUG_ONLY(verify_bit(range_beg);)
+  DEBUG_ONLY(verify_bit(range_end);)
+  assert(range_beg <= range_end, "live range invalid");
+
+  // The bitmap routines require the right boundary to be word-aligned.
+  const idx_t search_end = BitMap::word_align_up(range_end);
+
+  idx_t cur_beg = find_obj_beg(range_beg, search_end);
+  while (cur_beg < range_end) {
+    const idx_t cur_end = find_obj_end(cur_beg, search_end);
+    if (cur_end >= range_end) {
+      // The obj ends outside the range.
+      live_closure->set_source(bit_to_addr(cur_beg));
+      return incomplete;
+    }
+
+    const size_t size = obj_size(cur_beg, cur_end);
+    IterationStatus status = live_closure->do_addr(bit_to_addr(cur_beg), size);
+    if (status != incomplete) {
+      assert(status == would_overflow || status == full, "sanity");
+      return status;
+    }
+
+    // Successfully processed the object; look for the next object.
+    cur_beg = find_obj_beg(cur_end + 1, search_end);
+  }
+
+  live_closure->set_source(bit_to_addr(range_end));
+  return complete;
+}
+
+ParMarkBitMap::IterationStatus
+ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
+                       ParMarkBitMapClosure* dead_closure,
+                       idx_t range_beg, idx_t range_end,
+                       idx_t dead_range_end) const
+{
+  DEBUG_ONLY(verify_bit(range_beg);)
+  DEBUG_ONLY(verify_bit(range_end);)
+  DEBUG_ONLY(verify_bit(dead_range_end);)
+  assert(range_beg <= range_end, "live range invalid");
+  assert(range_end <= dead_range_end, "dead range invalid");
+
+  // The bitmap routines require the right boundary to be word-aligned.
+  const idx_t live_search_end = BitMap::word_align_up(range_end);
+  const idx_t dead_search_end = BitMap::word_align_up(dead_range_end);
+
+  idx_t cur_beg = range_beg;
+  if (range_beg < range_end && is_unmarked(range_beg)) {
+    // The range starts with dead space.  Look for the next object, then fill.
+    cur_beg = find_obj_beg(range_beg + 1, dead_search_end);
+    const idx_t dead_space_end = MIN2(cur_beg - 1, dead_range_end - 1);
+    const size_t size = obj_size(range_beg, dead_space_end);
+    dead_closure->do_addr(bit_to_addr(range_beg), size);
+  }
+
+  while (cur_beg < range_end) {
+    const idx_t cur_end = find_obj_end(cur_beg, live_search_end);
+    if (cur_end >= range_end) {
+      // The obj ends outside the range.
+      live_closure->set_source(bit_to_addr(cur_beg));
+      return incomplete;
+    }
+
+    const size_t size = obj_size(cur_beg, cur_end);
+    IterationStatus status = live_closure->do_addr(bit_to_addr(cur_beg), size);
+    if (status != incomplete) {
+      assert(status == would_overflow || status == full, "sanity");
+      return status;
+    }
+
+    // Look for the start of the next object.
+    const idx_t dead_space_beg = cur_end + 1;
+    cur_beg = find_obj_beg(dead_space_beg, dead_search_end);
+    if (cur_beg > dead_space_beg) {
+      // Found dead space; compute the size and invoke the dead closure.
+      const idx_t dead_space_end = MIN2(cur_beg - 1, dead_range_end - 1);
+      const size_t size = obj_size(dead_space_beg, dead_space_end);
+      dead_closure->do_addr(bit_to_addr(dead_space_beg), size);
+    }
+  }
+
+  live_closure->set_source(bit_to_addr(range_end));
+  return complete;
+}
+
+#ifndef PRODUCT
+void ParMarkBitMap::reset_counters()
+{
+  _cas_tries = _cas_retries = _cas_by_another = 0;
+}
+#endif  // #ifndef PRODUCT
+
+#ifdef ASSERT
+void ParMarkBitMap::verify_clear() const
+{
+  const idx_t* const beg = (const idx_t*)_virtual_space->committed_low_addr();
+  const idx_t* const end = (const idx_t*)_virtual_space->committed_high_addr();
+  for (const idx_t* p = beg; p < end; ++p) {
+    assert(*p == 0, "bitmap not clear");
+  }
+}
+#endif  // #ifdef ASSERT