--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/spaceDecorator.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2002, 2015, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/shared/space.inline.hpp"
+#include "gc/shared/spaceDecorator.hpp"
+#include "logging/log.hpp"
+#include "utilities/copy.hpp"
+
+// 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(!CheckZapUnusedHeapArea || 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
+ Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord);
+#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