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src/share/vm/memory/memRegion.cpp@2c022e432e10 (annotated)

src/share/vm/memory/memRegion.cpp

Fri, 20 Sep 2013 10:53:28 +0200

author

stefank

date

Fri, 20 Sep 2013 10:53:28 +0200

changeset 5769

2c022e432e10

parent 5614

9758d9f36299

child 6876

710a3c8b516e

child 7074

833b0f92429a

permissions

-rw-r--r--

8024974: Incorrect use of GC_locker::is_active()
Summary: SymbolTable and StringTable can make calls to GC_locker::is_active() outside a safepoint. This isn't safe because the GC_locker active state (lock count) is only updated at a safepoint and only remains valid as long as _needs_gc is true. However, outside a safepoint_needs_gc can change to false at any time, which makes it impossible to do a correct call to is_active() in that context. In this case these calls can just be removed since the input argument to basic_add() should never be on the heap and so there's no need to check the GC_locker state. This change also adjusts the assert() in is_active() to makes sure all calls to this function are always done under a safepoint.
Reviewed-by: brutisso, dcubed
Contributed-by: per.liden@oracle.com

duke@435	1	/*
coleenp@5614	2	* Copyright (c) 2000, 2013, Oracle and/or its affiliates. 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	*
trims@1907	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907	20	* or visit www.oracle.com if you need additional information or have any
trims@1907	21	* questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
stefank@2314	25	#include "precompiled.hpp"
minqi@5103	26	#include "memory/allocation.hpp"
minqi@5103	27	#include "memory/allocation.inline.hpp"
stefank@2314	28	#include "memory/memRegion.hpp"
stefank@2314	29	#include "runtime/globals.hpp"
stefank@2314	30
duke@435	31	// A very simple data structure representing a contigous word-aligned
duke@435	32	// region of address space.
duke@435	33
duke@435	34	MemRegion MemRegion::intersection(const MemRegion mr2) const {
duke@435	35	MemRegion res;
duke@435	36	HeapWord* res_start = MAX2(start(), mr2.start());
duke@435	37	HeapWord* res_end = MIN2(end(), mr2.end());
duke@435	38	if (res_start < res_end) {
duke@435	39	res.set_start(res_start);
duke@435	40	res.set_end(res_end);
duke@435	41	}
duke@435	42	return res;
duke@435	43	}
duke@435	44
duke@435	45	MemRegion MemRegion::_union(const MemRegion mr2) const {
duke@435	46	// If one region is empty, return the other
duke@435	47	if (is_empty()) return mr2;
duke@435	48	if (mr2.is_empty()) return MemRegion(start(), end());
duke@435	49
duke@435	50	// Otherwise, regions must overlap or be adjacent
duke@435	51	assert(((start() <= mr2.start()) && (end() >= mr2.start())) ||
duke@435	52	((mr2.start() <= start()) && (mr2.end() >= start())),
duke@435	53	"non-adjacent or overlapping regions");
duke@435	54	MemRegion res;
duke@435	55	HeapWord* res_start = MIN2(start(), mr2.start());
duke@435	56	HeapWord* res_end = MAX2(end(), mr2.end());
duke@435	57	res.set_start(res_start);
duke@435	58	res.set_end(res_end);
duke@435	59	return res;
duke@435	60	}
duke@435	61
duke@435	62	MemRegion MemRegion::minus(const MemRegion mr2) const {
duke@435	63	// There seem to be 6 cases:
duke@435	64	// |this MemRegion|
duke@435	65	// |strictly below|
duke@435	66	// |overlap beginning|
duke@435	67	// |interior|
duke@435	68	// |overlap ending|
duke@435	69	// |strictly above|
duke@435	70	// |completely overlapping|
duke@435	71	// We can't deal with an interior case because it would
duke@435	72	// produce two disjoint regions as a result.
duke@435	73	// We aren't trying to be optimal in the number of tests below,
duke@435	74	// but the order is important to distinguish the strictly cases
duke@435	75	// from the overlapping cases.
duke@435	76	if (mr2.end() <= start()) {
duke@435	77	// strictly below
duke@435	78	return MemRegion(start(), end());
duke@435	79	}
duke@435	80	if (mr2.start() <= start() && mr2.end() <= end()) {
duke@435	81	// overlap beginning
duke@435	82	return MemRegion(mr2.end(), end());
duke@435	83	}
duke@435	84	if (mr2.start() >= end()) {
duke@435	85	// strictly above
duke@435	86	return MemRegion(start(), end());
duke@435	87	}
duke@435	88	if (mr2.start() >= start() && mr2.end() >= end()) {
duke@435	89	// overlap ending
duke@435	90	return MemRegion(start(), mr2.start());
duke@435	91	}
duke@435	92	if (mr2.start() <= start() && mr2.end() >= end()) {
duke@435	93	// completely overlapping
duke@435	94	return MemRegion();
duke@435	95	}
duke@435	96	if (mr2.start() > start() && mr2.end() < end()) {
duke@435	97	// interior
duke@435	98	guarantee(false, "MemRegion::minus, but interior");
duke@435	99	return MemRegion();
duke@435	100	}
duke@435	101	ShouldNotReachHere();
duke@435	102	return MemRegion();
duke@435	103	}
minqi@5103	104
coleenp@5614	105	void* MemRegion::operator new(size_t size) throw() {
minqi@5103	106	return (address)AllocateHeap(size, mtGC, 0, AllocFailStrategy::RETURN_NULL);
minqi@5103	107	}
minqi@5103	108
coleenp@5614	109	void* MemRegion::operator new [](size_t size) throw() {
minqi@5103	110	return (address)AllocateHeap(size, mtGC, 0, AllocFailStrategy::RETURN_NULL);
minqi@5103	111	}
minqi@5103	112	void MemRegion::operator delete(void* p) {
minqi@5103	113	FreeHeap(p, mtGC);
minqi@5103	114	}
minqi@5103	115
minqi@5103	116	void MemRegion::operator delete [](void* p) {
minqi@5103	117	FreeHeap(p, mtGC);
minqi@5103	118	}
minqi@5103	119