--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/shared/spaceDecorator.cpp	Wed Jul 09 15:08:55 2008 -0700
@@ -0,0 +1,140 @@
+/*
+ * Copyright 2002-2005 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/_spaceDecorator.cpp.incl"
+
+// Catch-all file for utility classes
+
+#ifndef PRODUCT
+
+// Returns true is the location q matches the mangling
+// pattern.
+bool SpaceMangler::is_mangled(HeapWord* q) {
+  // This test loses precision but is good enough
+  return badHeapWord == (max_juint & (uintptr_t) q->value());
+}
+
+
+void SpaceMangler::set_top_for_allocations(HeapWord* v)  {
+  if (v < end()) {
+    assert(is_mangled(v), "The high water mark is not mangled");
+  }
+  _top_for_allocations = v;
+}
+
+// Mangle only the unused space that has not previously
+// been mangled and that has not been allocated since being
+// mangled.
+void SpaceMangler::mangle_unused_area() {
+  assert(ZapUnusedHeapArea, "Mangling should not be in use");
+  // Mangle between top and the high water mark.  Safeguard
+  // against the space changing since top_for_allocations was
+  // set.
+  HeapWord* mangled_end = MIN2(top_for_allocations(), end());
+  if (top() < mangled_end) {
+    MemRegion mangle_mr(top(), mangled_end);
+    SpaceMangler::mangle_region(mangle_mr);
+    // Light weight check of mangling.
+    check_mangled_unused_area(end());
+  }
+  // Complete check of unused area which is functional when
+  // DEBUG_MANGLING is defined.
+  check_mangled_unused_area_complete();
+}
+
+// A complete mangle is expected in the
+// exceptional case where top_for_allocations is not
+// properly tracking the high water mark for mangling.
+// This can be the case when to-space is being used for
+// scratch space during a mark-sweep-compact.  See
+// contribute_scratch() and PSMarkSweep::allocate_stacks().
+void SpaceMangler::mangle_unused_area_complete() {
+  assert(ZapUnusedHeapArea, "Mangling should not be in use");
+  MemRegion mangle_mr(top(), end());
+  SpaceMangler::mangle_region(mangle_mr);
+}
+
+// Simply mangle the MemRegion mr.
+void SpaceMangler::mangle_region(MemRegion mr) {
+  assert(ZapUnusedHeapArea, "Mangling should not be in use");
+#ifdef ASSERT
+  if(TraceZapUnusedHeapArea) {
+    gclog_or_tty->print("Mangling [0x%x to 0x%x)", mr.start(), mr.end());
+  }
+  Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord);
+  if(TraceZapUnusedHeapArea) {
+    gclog_or_tty->print_cr(" done");
+  }
+#endif
+}
+
+// Check that top, top_for_allocations and the last
+// word of the space are mangled.  In a tight memory
+// situation even this light weight mangling could
+// cause paging by touching the end of the space.
+void  SpaceMangler::check_mangled_unused_area(HeapWord* limit) {
+  if (CheckZapUnusedHeapArea) {
+    // This method can be called while the spaces are
+    // being reshaped so skip the test if the end of the
+    // space is beyond the specified limit;
+    if (end() > limit) return;
+
+    assert(top() == end() ||
+           (is_mangled(top())), "Top not mangled");
+    assert((top_for_allocations() < top()) ||
+           (top_for_allocations() >= end()) ||
+           (is_mangled(top_for_allocations())),
+           "Older unused not mangled");
+    assert(top() == end() ||
+           (is_mangled(end() - 1)), "End not properly mangled");
+    // Only does checking when DEBUG_MANGLING is defined.
+    check_mangled_unused_area_complete();
+  }
+}
+
+#undef DEBUG_MANGLING
+// This should only be used while debugging the mangling
+// because of the high cost of checking the completeness.
+void  SpaceMangler::check_mangled_unused_area_complete() {
+  if (CheckZapUnusedHeapArea) {
+    assert(ZapUnusedHeapArea, "Not mangling unused area");
+#ifdef DEBUG_MANGLING
+    HeapWord* q = top();
+    HeapWord* limit = end();
+
+    bool passed = true;
+    while (q < limit) {
+      if (!is_mangled(q)) {
+        passed = false;
+        break;
+      }
+      q++;
+    }
+    assert(passed, "Mangling is not complete");
+#endif
+  }
+}
+#undef DEBUG_MANGLING
+#endif // not PRODUCT