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src/share/vm/memory/memRegion.cpp@a61af66fc99e (annotated)

src/share/vm/memory/memRegion.cpp

Sat, 01 Dec 2007 00:00:00 +0000

author

duke

date

Sat, 01 Dec 2007 00:00:00 +0000

changeset 435

a61af66fc99e

child 1907

c18cbe5936b8

permissions

-rw-r--r--

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duke@435	1	/*
duke@435	2	* Copyright 2000-2004 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	// A very simple data structure representing a contigous word-aligned
duke@435	26	// region of address space.
duke@435	27
duke@435	28	#include "incls/_precompiled.incl"
duke@435	29	#include "incls/_memRegion.cpp.incl"
duke@435	30
duke@435	31	MemRegion MemRegion::intersection(const MemRegion mr2) const {
duke@435	32	MemRegion res;
duke@435	33	HeapWord* res_start = MAX2(start(), mr2.start());
duke@435	34	HeapWord* res_end = MIN2(end(), mr2.end());
duke@435	35	if (res_start < res_end) {
duke@435	36	res.set_start(res_start);
duke@435	37	res.set_end(res_end);
duke@435	38	}
duke@435	39	return res;
duke@435	40	}
duke@435	41
duke@435	42	MemRegion MemRegion::_union(const MemRegion mr2) const {
duke@435	43	// If one region is empty, return the other
duke@435	44	if (is_empty()) return mr2;
duke@435	45	if (mr2.is_empty()) return MemRegion(start(), end());
duke@435	46
duke@435	47	// Otherwise, regions must overlap or be adjacent
duke@435	48	assert(((start() <= mr2.start()) && (end() >= mr2.start())) ||
duke@435	49	((mr2.start() <= start()) && (mr2.end() >= start())),
duke@435	50	"non-adjacent or overlapping regions");
duke@435	51	MemRegion res;
duke@435	52	HeapWord* res_start = MIN2(start(), mr2.start());
duke@435	53	HeapWord* res_end = MAX2(end(), mr2.end());
duke@435	54	res.set_start(res_start);
duke@435	55	res.set_end(res_end);
duke@435	56	return res;
duke@435	57	}
duke@435	58
duke@435	59	MemRegion MemRegion::minus(const MemRegion mr2) const {
duke@435	60	// There seem to be 6 cases:
duke@435	61	// |this MemRegion|
duke@435	62	// |strictly below|
duke@435	63	// |overlap beginning|
duke@435	64	// |interior|
duke@435	65	// |overlap ending|
duke@435	66	// |strictly above|
duke@435	67	// |completely overlapping|
duke@435	68	// We can't deal with an interior case because it would
duke@435	69	// produce two disjoint regions as a result.
duke@435	70	// We aren't trying to be optimal in the number of tests below,
duke@435	71	// but the order is important to distinguish the strictly cases
duke@435	72	// from the overlapping cases.
duke@435	73	if (mr2.end() <= start()) {
duke@435	74	// strictly below
duke@435	75	return MemRegion(start(), end());
duke@435	76	}
duke@435	77	if (mr2.start() <= start() && mr2.end() <= end()) {
duke@435	78	// overlap beginning
duke@435	79	return MemRegion(mr2.end(), end());
duke@435	80	}
duke@435	81	if (mr2.start() >= end()) {
duke@435	82	// strictly above
duke@435	83	return MemRegion(start(), end());
duke@435	84	}
duke@435	85	if (mr2.start() >= start() && mr2.end() >= end()) {
duke@435	86	// overlap ending
duke@435	87	return MemRegion(start(), mr2.start());
duke@435	88	}
duke@435	89	if (mr2.start() <= start() && mr2.end() >= end()) {
duke@435	90	// completely overlapping
duke@435	91	return MemRegion();
duke@435	92	}
duke@435	93	if (mr2.start() > start() && mr2.end() < end()) {
duke@435	94	// interior
duke@435	95	guarantee(false, "MemRegion::minus, but interior");
duke@435	96	return MemRegion();
duke@435	97	}
duke@435	98	ShouldNotReachHere();
duke@435	99	return MemRegion();
duke@435	100	}