1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/shared/spaceDecorator.cpp Wed Jul 09 15:08:55 2008 -0700
1.3 @@ -0,0 +1,140 @@
1.4 +/*
1.5 + * Copyright 2002-2005 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +# include "incls/_precompiled.incl"
1.29 +# include "incls/_spaceDecorator.cpp.incl"
1.30 +
1.31 +// Catch-all file for utility classes
1.32 +
1.33 +#ifndef PRODUCT
1.34 +
1.35 +// Returns true is the location q matches the mangling
1.36 +// pattern.
1.37 +bool SpaceMangler::is_mangled(HeapWord* q) {
1.38 + // This test loses precision but is good enough
1.39 + return badHeapWord == (max_juint & (uintptr_t) q->value());
1.40 +}
1.41 +
1.42 +
1.43 +void SpaceMangler::set_top_for_allocations(HeapWord* v) {
1.44 + if (v < end()) {
1.45 + assert(is_mangled(v), "The high water mark is not mangled");
1.46 + }
1.47 + _top_for_allocations = v;
1.48 +}
1.49 +
1.50 +// Mangle only the unused space that has not previously
1.51 +// been mangled and that has not been allocated since being
1.52 +// mangled.
1.53 +void SpaceMangler::mangle_unused_area() {
1.54 + assert(ZapUnusedHeapArea, "Mangling should not be in use");
1.55 + // Mangle between top and the high water mark. Safeguard
1.56 + // against the space changing since top_for_allocations was
1.57 + // set.
1.58 + HeapWord* mangled_end = MIN2(top_for_allocations(), end());
1.59 + if (top() < mangled_end) {
1.60 + MemRegion mangle_mr(top(), mangled_end);
1.61 + SpaceMangler::mangle_region(mangle_mr);
1.62 + // Light weight check of mangling.
1.63 + check_mangled_unused_area(end());
1.64 + }
1.65 + // Complete check of unused area which is functional when
1.66 + // DEBUG_MANGLING is defined.
1.67 + check_mangled_unused_area_complete();
1.68 +}
1.69 +
1.70 +// A complete mangle is expected in the
1.71 +// exceptional case where top_for_allocations is not
1.72 +// properly tracking the high water mark for mangling.
1.73 +// This can be the case when to-space is being used for
1.74 +// scratch space during a mark-sweep-compact. See
1.75 +// contribute_scratch() and PSMarkSweep::allocate_stacks().
1.76 +void SpaceMangler::mangle_unused_area_complete() {
1.77 + assert(ZapUnusedHeapArea, "Mangling should not be in use");
1.78 + MemRegion mangle_mr(top(), end());
1.79 + SpaceMangler::mangle_region(mangle_mr);
1.80 +}
1.81 +
1.82 +// Simply mangle the MemRegion mr.
1.83 +void SpaceMangler::mangle_region(MemRegion mr) {
1.84 + assert(ZapUnusedHeapArea, "Mangling should not be in use");
1.85 +#ifdef ASSERT
1.86 + if(TraceZapUnusedHeapArea) {
1.87 + gclog_or_tty->print("Mangling [0x%x to 0x%x)", mr.start(), mr.end());
1.88 + }
1.89 + Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord);
1.90 + if(TraceZapUnusedHeapArea) {
1.91 + gclog_or_tty->print_cr(" done");
1.92 + }
1.93 +#endif
1.94 +}
1.95 +
1.96 +// Check that top, top_for_allocations and the last
1.97 +// word of the space are mangled. In a tight memory
1.98 +// situation even this light weight mangling could
1.99 +// cause paging by touching the end of the space.
1.100 +void SpaceMangler::check_mangled_unused_area(HeapWord* limit) {
1.101 + if (CheckZapUnusedHeapArea) {
1.102 + // This method can be called while the spaces are
1.103 + // being reshaped so skip the test if the end of the
1.104 + // space is beyond the specified limit;
1.105 + if (end() > limit) return;
1.106 +
1.107 + assert(top() == end() ||
1.108 + (is_mangled(top())), "Top not mangled");
1.109 + assert((top_for_allocations() < top()) ||
1.110 + (top_for_allocations() >= end()) ||
1.111 + (is_mangled(top_for_allocations())),
1.112 + "Older unused not mangled");
1.113 + assert(top() == end() ||
1.114 + (is_mangled(end() - 1)), "End not properly mangled");
1.115 + // Only does checking when DEBUG_MANGLING is defined.
1.116 + check_mangled_unused_area_complete();
1.117 + }
1.118 +}
1.119 +
1.120 +#undef DEBUG_MANGLING
1.121 +// This should only be used while debugging the mangling
1.122 +// because of the high cost of checking the completeness.
1.123 +void SpaceMangler::check_mangled_unused_area_complete() {
1.124 + if (CheckZapUnusedHeapArea) {
1.125 + assert(ZapUnusedHeapArea, "Not mangling unused area");
1.126 +#ifdef DEBUG_MANGLING
1.127 + HeapWord* q = top();
1.128 + HeapWord* limit = end();
1.129 +
1.130 + bool passed = true;
1.131 + while (q < limit) {
1.132 + if (!is_mangled(q)) {
1.133 + passed = false;
1.134 + break;
1.135 + }
1.136 + q++;
1.137 + }
1.138 + assert(passed, "Mangling is not complete");
1.139 +#endif
1.140 + }
1.141 +}
1.142 +#undef DEBUG_MANGLING
1.143 +#endif // not PRODUCT
