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

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+/*
+ * Copyright 2002-2006 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/_psPromotionLAB.cpp.incl"
+
+const size_t PSPromotionLAB::filler_header_size = align_object_size(typeArrayOopDesc::header_size(T_INT));
+
+// This is the shared initialization code. It sets up the basic pointers,
+// and allows enough extra space for a filler object. We call a virtual
+// method, "lab_is_valid()" to handle the different asserts the old/young
+// labs require.
+void PSPromotionLAB::initialize(MemRegion lab) {
+  assert(lab_is_valid(lab), "Sanity");
+
+  HeapWord* bottom = lab.start();
+  HeapWord* end    = lab.end();
+
+  set_bottom(bottom);
+  set_end(end);
+  set_top(bottom);
+
+  // We can be initialized to a zero size!
+  if (free() > 0) {
+    if (ZapUnusedHeapArea) {
+      debug_only(Copy::fill_to_words(top(), free()/HeapWordSize, badHeapWord));
+    }
+
+    // NOTE! We need to allow space for a filler object.
+    assert(lab.word_size() >= filler_header_size, "lab is too small");
+    end = end - filler_header_size;
+    set_end(end);
+
+    _state = needs_flush;
+  } else {
+    _state = zero_size;
+  }
+
+  assert(this->top() <= this->end(), "pointers out of order");
+}
+
+// Fill all remaining lab space with an unreachable object.
+// The goal is to leave a contiguous parseable span of objects.
+void PSPromotionLAB::flush() {
+  assert(_state != flushed, "Attempt to flush PLAB twice");
+  assert(top() <= end(), "pointers out of order");
+
+  // If we were initialized to a zero sized lab, there is
+  // nothing to flush
+  if (_state == zero_size)
+    return;
+
+  // PLAB's never allocate the last aligned_header_size
+  // so they can always fill with an array.
+  HeapWord* tlab_end = end() + filler_header_size;
+  typeArrayOop filler_oop = (typeArrayOop) top();
+  filler_oop->set_mark(markOopDesc::prototype());
+  filler_oop->set_klass(Universe::intArrayKlassObj());
+  const size_t array_length =
+    pointer_delta(tlab_end, top()) - typeArrayOopDesc::header_size(T_INT);
+  assert( (array_length * (HeapWordSize/sizeof(jint))) < (size_t)max_jint, "array too big in PSPromotionLAB");
+  filler_oop->set_length((int)(array_length * (HeapWordSize/sizeof(jint))));
+
+#ifdef ASSERT
+  // Note that we actually DO NOT want to use the aligned header size!
+  HeapWord* elt_words = ((HeapWord*)filler_oop) + typeArrayOopDesc::header_size(T_INT);
+  Copy::fill_to_words(elt_words, array_length, 0xDEAABABE);
+#endif
+
+  set_bottom(NULL);
+  set_end(NULL);
+  set_top(NULL);
+
+  _state = flushed;
+}
+
+bool PSPromotionLAB::unallocate_object(oop obj) {
+  assert(Universe::heap()->is_in(obj), "Object outside heap");
+
+  if (contains(obj)) {
+    HeapWord* object_end = (HeapWord*)obj + obj->size();
+    assert(object_end <= top(), "Object crosses promotion LAB boundary");
+
+    if (object_end == top()) {
+      set_top((HeapWord*)obj);
+      return true;
+    }
+  }
+
+  return false;
+}
+
+// Fill all remaining lab space with an unreachable object.
+// The goal is to leave a contiguous parseable span of objects.
+void PSOldPromotionLAB::flush() {
+  assert(_state != flushed, "Attempt to flush PLAB twice");
+  assert(top() <= end(), "pointers out of order");
+
+  if (_state == zero_size)
+    return;
+
+  HeapWord* obj = top();
+
+  PSPromotionLAB::flush();
+
+  assert(_start_array != NULL, "Sanity");
+
+  _start_array->allocate_block(obj);
+}
+
+#ifdef ASSERT
+
+bool PSYoungPromotionLAB::lab_is_valid(MemRegion lab) {
+  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
+  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
+
+  MutableSpace* to_space = heap->young_gen()->to_space();
+  MemRegion used = to_space->used_region();
+  if (used.contains(lab)) {
+    return true;
+  }
+
+  return false;
+}
+
+bool PSOldPromotionLAB::lab_is_valid(MemRegion lab) {
+  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
+  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
+  assert(_start_array->covered_region().contains(lab), "Sanity");
+
+  PSOldGen* old_gen = heap->old_gen();
+  MemRegion used = old_gen->object_space()->used_region();
+
+  if (used.contains(lab)) {
+    return true;
+  }
+
+  return false;
+}
+
+#endif /* ASSERT */