0N/A/*
1879N/A * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
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0N/A * This code is free software; you can redistribute it and/or modify it
0N/A * under the terms of the GNU General Public License version 2 only, as
0N/A * published by the Free Software Foundation.
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0N/A * This code is distributed in the hope that it will be useful, but WITHOUT
0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
0N/A * version 2 for more details (a copy is included in the LICENSE file that
0N/A * accompanied this code).
0N/A *
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0N/A * 2 along with this work; if not, write to the Free Software Foundation,
0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
0N/A *
1472N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1472N/A * or visit www.oracle.com if you need additional information or have any
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0N/A */
0N/A
1879N/A#include "precompiled.hpp"
1879N/A#include "memory/memRegion.hpp"
1879N/A#include "runtime/globals.hpp"
1879N/A
0N/A// A very simple data structure representing a contigous word-aligned
0N/A// region of address space.
0N/A
0N/AMemRegion MemRegion::intersection(const MemRegion mr2) const {
0N/A MemRegion res;
0N/A HeapWord* res_start = MAX2(start(), mr2.start());
0N/A HeapWord* res_end = MIN2(end(), mr2.end());
0N/A if (res_start < res_end) {
0N/A res.set_start(res_start);
0N/A res.set_end(res_end);
0N/A }
0N/A return res;
0N/A}
0N/A
0N/AMemRegion MemRegion::_union(const MemRegion mr2) const {
0N/A // If one region is empty, return the other
0N/A if (is_empty()) return mr2;
0N/A if (mr2.is_empty()) return MemRegion(start(), end());
0N/A
0N/A // Otherwise, regions must overlap or be adjacent
0N/A assert(((start() <= mr2.start()) && (end() >= mr2.start())) ||
0N/A ((mr2.start() <= start()) && (mr2.end() >= start())),
0N/A "non-adjacent or overlapping regions");
0N/A MemRegion res;
0N/A HeapWord* res_start = MIN2(start(), mr2.start());
0N/A HeapWord* res_end = MAX2(end(), mr2.end());
0N/A res.set_start(res_start);
0N/A res.set_end(res_end);
0N/A return res;
0N/A}
0N/A
0N/AMemRegion MemRegion::minus(const MemRegion mr2) const {
0N/A // There seem to be 6 cases:
0N/A // |this MemRegion|
0N/A // |strictly below|
0N/A // |overlap beginning|
0N/A // |interior|
0N/A // |overlap ending|
0N/A // |strictly above|
0N/A // |completely overlapping|
0N/A // We can't deal with an interior case because it would
0N/A // produce two disjoint regions as a result.
0N/A // We aren't trying to be optimal in the number of tests below,
0N/A // but the order is important to distinguish the strictly cases
0N/A // from the overlapping cases.
0N/A if (mr2.end() <= start()) {
0N/A // strictly below
0N/A return MemRegion(start(), end());
0N/A }
0N/A if (mr2.start() <= start() && mr2.end() <= end()) {
0N/A // overlap beginning
0N/A return MemRegion(mr2.end(), end());
0N/A }
0N/A if (mr2.start() >= end()) {
0N/A // strictly above
0N/A return MemRegion(start(), end());
0N/A }
0N/A if (mr2.start() >= start() && mr2.end() >= end()) {
0N/A // overlap ending
0N/A return MemRegion(start(), mr2.start());
0N/A }
0N/A if (mr2.start() <= start() && mr2.end() >= end()) {
0N/A // completely overlapping
0N/A return MemRegion();
0N/A }
0N/A if (mr2.start() > start() && mr2.end() < end()) {
0N/A // interior
0N/A guarantee(false, "MemRegion::minus, but interior");
0N/A return MemRegion();
0N/A }
0N/A ShouldNotReachHere();
0N/A return MemRegion();
0N/A}