Wed, 23 Jan 2013 13:02:39 -0500
8005915: Unify SERIALGC and INCLUDE_ALTERNATE_GCS
Summary: Rename INCLUDE_ALTERNATE_GCS to INCLUDE_ALL_GCS and replace SERIALGC with INCLUDE_ALL_GCS.
Reviewed-by: coleenp, stefank
1 /*
2 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/shared/spaceDecorator.hpp"
27 #include "memory/space.inline.hpp"
28 #include "utilities/copy.hpp"
30 // Catch-all file for utility classes
32 #ifndef PRODUCT
34 // Returns true is the location q matches the mangling
35 // pattern.
36 bool SpaceMangler::is_mangled(HeapWord* q) {
37 // This test loses precision but is good enough
38 return badHeapWord == (max_juint & (uintptr_t) q->value());
39 }
42 void SpaceMangler::set_top_for_allocations(HeapWord* v) {
43 if (v < end()) {
44 assert(!CheckZapUnusedHeapArea || is_mangled(v),
45 "The high water mark is not mangled");
46 }
47 _top_for_allocations = v;
48 }
50 // Mangle only the unused space that has not previously
51 // been mangled and that has not been allocated since being
52 // mangled.
53 void SpaceMangler::mangle_unused_area() {
54 assert(ZapUnusedHeapArea, "Mangling should not be in use");
55 // Mangle between top and the high water mark. Safeguard
56 // against the space changing since top_for_allocations was
57 // set.
58 HeapWord* mangled_end = MIN2(top_for_allocations(), end());
59 if (top() < mangled_end) {
60 MemRegion mangle_mr(top(), mangled_end);
61 SpaceMangler::mangle_region(mangle_mr);
62 // Light weight check of mangling.
63 check_mangled_unused_area(end());
64 }
65 // Complete check of unused area which is functional when
66 // DEBUG_MANGLING is defined.
67 check_mangled_unused_area_complete();
68 }
70 // A complete mangle is expected in the
71 // exceptional case where top_for_allocations is not
72 // properly tracking the high water mark for mangling.
73 // This can be the case when to-space is being used for
74 // scratch space during a mark-sweep-compact. See
75 // contribute_scratch() and PSMarkSweep::allocate_stacks().
76 void SpaceMangler::mangle_unused_area_complete() {
77 assert(ZapUnusedHeapArea, "Mangling should not be in use");
78 MemRegion mangle_mr(top(), end());
79 SpaceMangler::mangle_region(mangle_mr);
80 }
82 // Simply mangle the MemRegion mr.
83 void SpaceMangler::mangle_region(MemRegion mr) {
84 assert(ZapUnusedHeapArea, "Mangling should not be in use");
85 #ifdef ASSERT
86 if(TraceZapUnusedHeapArea) {
87 gclog_or_tty->print("Mangling [0x%x to 0x%x)", mr.start(), mr.end());
88 }
89 Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord);
90 if(TraceZapUnusedHeapArea) {
91 gclog_or_tty->print_cr(" done");
92 }
93 #endif
94 }
96 // Check that top, top_for_allocations and the last
97 // word of the space are mangled. In a tight memory
98 // situation even this light weight mangling could
99 // cause paging by touching the end of the space.
100 void SpaceMangler::check_mangled_unused_area(HeapWord* limit) {
101 if (CheckZapUnusedHeapArea) {
102 // This method can be called while the spaces are
103 // being reshaped so skip the test if the end of the
104 // space is beyond the specified limit;
105 if (end() > limit) return;
107 assert(top() == end() ||
108 (is_mangled(top())), "Top not mangled");
109 assert((top_for_allocations() < top()) ||
110 (top_for_allocations() >= end()) ||
111 (is_mangled(top_for_allocations())),
112 "Older unused not mangled");
113 assert(top() == end() ||
114 (is_mangled(end() - 1)), "End not properly mangled");
115 // Only does checking when DEBUG_MANGLING is defined.
116 check_mangled_unused_area_complete();
117 }
118 }
120 #undef DEBUG_MANGLING
121 // This should only be used while debugging the mangling
122 // because of the high cost of checking the completeness.
123 void SpaceMangler::check_mangled_unused_area_complete() {
124 if (CheckZapUnusedHeapArea) {
125 assert(ZapUnusedHeapArea, "Not mangling unused area");
126 #ifdef DEBUG_MANGLING
127 HeapWord* q = top();
128 HeapWord* limit = end();
130 bool passed = true;
131 while (q < limit) {
132 if (!is_mangled(q)) {
133 passed = false;
134 break;
135 }
136 q++;
137 }
138 assert(passed, "Mangling is not complete");
139 #endif
140 }
141 }
142 #undef DEBUG_MANGLING
143 #endif // not PRODUCT