hotspot/src/share/vm/memory/memRegion.cpp
author tonyp
Tue, 08 Nov 2011 00:41:28 -0500
changeset 10997 0be4b3be7197
parent 7397 5b173b4ca846
child 17376 4ee999c3c007
permissions -rw-r--r--
7099849: G1: include heap region information in hs_err files Reviewed-by: johnc, brutisso, poonam
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/*
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 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "memory/memRegion.hpp"
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#include "runtime/globals.hpp"
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// A very simple data structure representing a contigous word-aligned
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// region of address space.
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MemRegion MemRegion::intersection(const MemRegion mr2) const {
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  MemRegion res;
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  HeapWord* res_start = MAX2(start(), mr2.start());
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  HeapWord* res_end   = MIN2(end(),   mr2.end());
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  if (res_start < res_end) {
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    res.set_start(res_start);
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    res.set_end(res_end);
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  }
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  return res;
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}
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MemRegion MemRegion::_union(const MemRegion mr2) const {
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  // If one region is empty, return the other
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  if (is_empty()) return mr2;
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  if (mr2.is_empty()) return MemRegion(start(), end());
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  // Otherwise, regions must overlap or be adjacent
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  assert(((start() <= mr2.start()) && (end() >= mr2.start())) ||
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         ((mr2.start() <= start()) && (mr2.end() >= start())),
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             "non-adjacent or overlapping regions");
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  MemRegion res;
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  HeapWord* res_start = MIN2(start(), mr2.start());
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  HeapWord* res_end   = MAX2(end(),   mr2.end());
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  res.set_start(res_start);
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  res.set_end(res_end);
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  return res;
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}
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MemRegion MemRegion::minus(const MemRegion mr2) const {
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  // There seem to be 6 cases:
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  //                  |this MemRegion|
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  // |strictly below|
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  //   |overlap beginning|
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  //                    |interior|
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  //                        |overlap ending|
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  //                                   |strictly above|
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  //              |completely overlapping|
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  // We can't deal with an interior case because it would
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  // produce two disjoint regions as a result.
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  // We aren't trying to be optimal in the number of tests below,
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  // but the order is important to distinguish the strictly cases
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  // from the overlapping cases.
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  if (mr2.end() <= start()) {
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    // strictly below
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    return MemRegion(start(), end());
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  }
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  if (mr2.start() <= start() && mr2.end() <= end()) {
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    // overlap beginning
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    return MemRegion(mr2.end(), end());
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  }
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  if (mr2.start() >= end()) {
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    // strictly above
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    return MemRegion(start(), end());
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  }
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  if (mr2.start() >= start() && mr2.end() >= end()) {
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    // overlap ending
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    return MemRegion(start(), mr2.start());
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  }
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  if (mr2.start() <= start() && mr2.end() >= end()) {
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    // completely overlapping
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    return MemRegion();
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  }
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  if (mr2.start() > start() && mr2.end() < end()) {
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    // interior
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    guarantee(false, "MemRegion::minus, but interior");
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    return MemRegion();
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  }
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  ShouldNotReachHere();
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  return MemRegion();
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}