/* * Copyright (c) 2000, 2020, 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 "memory/allocation.hpp" #include "memory/allocation.inline.hpp" #include "memory/memRegion.hpp" #include "runtime/globals.hpp" // A very simple data structure representing a contigous word-aligned // region of address space. MemRegion MemRegion::intersection(const MemRegion mr2) const { MemRegion res; HeapWord* res_start = MAX2(start(), mr2.start()); HeapWord* res_end = MIN2(end(), mr2.end()); if (res_start < res_end) { res.set_start(res_start); res.set_end(res_end); } return res; } MemRegion MemRegion::_union(const MemRegion mr2) const { // If one region is empty, return the other if (is_empty()) return mr2; if (mr2.is_empty()) return MemRegion(start(), end()); // Otherwise, regions must overlap or be adjacent assert(((start() <= mr2.start()) && (end() >= mr2.start())) || ((mr2.start() <= start()) && (mr2.end() >= start())), "non-adjacent or overlapping regions"); MemRegion res; HeapWord* res_start = MIN2(start(), mr2.start()); HeapWord* res_end = MAX2(end(), mr2.end()); res.set_start(res_start); res.set_end(res_end); return res; } MemRegion MemRegion::minus(const MemRegion mr2) const { // There seem to be 6 cases: // |this MemRegion| // |strictly below| // |overlap beginning| // |interior| // |overlap ending| // |strictly above| // |completely overlapping| // We can't deal with an interior case because it would // produce two disjoint regions as a result. // We aren't trying to be optimal in the number of tests below, // but the order is important to distinguish the strictly cases // from the overlapping cases. if (mr2.end() <= start()) { // strictly below return MemRegion(start(), end()); } if (mr2.start() <= start() && mr2.end() <= end()) { // overlap beginning return MemRegion(mr2.end(), end()); } if (mr2.start() >= end()) { // strictly above return MemRegion(start(), end()); } if (mr2.start() >= start() && mr2.end() >= end()) { // overlap ending return MemRegion(start(), mr2.start()); } if (mr2.start() <= start() && mr2.end() >= end()) { // completely overlapping return MemRegion(); } if (mr2.start() > start() && mr2.end() < end()) { // interior guarantee(false, "MemRegion::minus, but interior"); return MemRegion(); } ShouldNotReachHere(); return MemRegion(); } MemRegion* MemRegion::create(uint length, MEMFLAGS flags) { MemRegion* result = NEW_C_HEAP_ARRAY(MemRegion, length, flags); for (uint i = 0; i < length; i++) { ::new (&result[i]) MemRegion(); } return result; }