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src/share/vm/gc_implementation/shared/spaceDecorator.cpp@710a3c8b516e (annotated)

src/share/vm/gc_implementation/shared/spaceDecorator.cpp

Tue, 08 Aug 2017 15:57:29 +0800

author

aoqi

date

Tue, 08 Aug 2017 15:57:29 +0800

changeset 6876

710a3c8b516e

parent 6680

78bbf4d43a14

parent 0

f90c822e73f8

permissions

-rw-r--r--

merge

aoqi@0	1	/*
aoqi@0	2	* Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
aoqi@0	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0	4	*
aoqi@0	5	* This code is free software; you can redistribute it and/or modify it
aoqi@0	6	* under the terms of the GNU General Public License version 2 only, as
aoqi@0	7	* published by the Free Software Foundation.
aoqi@0	8	*
aoqi@0	9	* This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
aoqi@0	12	* version 2 for more details (a copy is included in the LICENSE file that
aoqi@0	13	* accompanied this code).
aoqi@0	14	*
aoqi@0	15	* You should have received a copy of the GNU General Public License version
aoqi@0	16	* 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0	18	*
aoqi@0	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0	20	* or visit www.oracle.com if you need additional information or have any
aoqi@0	21	* questions.
aoqi@0	22	*
aoqi@0	23	*/
aoqi@0	24
aoqi@0	25	#include "precompiled.hpp"
aoqi@0	26	#include "gc_implementation/shared/spaceDecorator.hpp"
aoqi@0	27	#include "memory/space.inline.hpp"
aoqi@0	28	#include "utilities/copy.hpp"
aoqi@0	29
aoqi@0	30	PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
aoqi@0	31
aoqi@0	32	// Catch-all file for utility classes
aoqi@0	33
aoqi@0	34	#ifndef PRODUCT
aoqi@0	35
aoqi@0	36	// Returns true is the location q matches the mangling
aoqi@0	37	// pattern.
aoqi@0	38	bool SpaceMangler::is_mangled(HeapWord* q) {
aoqi@0	39	// This test loses precision but is good enough
aoqi@0	40	return badHeapWord == (max_juint & (uintptr_t) q->value());
aoqi@0	41	}
aoqi@0	42
aoqi@0	43
aoqi@0	44	void SpaceMangler::set_top_for_allocations(HeapWord* v) {
aoqi@0	45	if (v < end()) {
aoqi@0	46	assert(!CheckZapUnusedHeapArea || is_mangled(v),
aoqi@0	47	"The high water mark is not mangled");
aoqi@0	48	}
aoqi@0	49	_top_for_allocations = v;
aoqi@0	50	}
aoqi@0	51
aoqi@0	52	// Mangle only the unused space that has not previously
aoqi@0	53	// been mangled and that has not been allocated since being
aoqi@0	54	// mangled.
aoqi@0	55	void SpaceMangler::mangle_unused_area() {
aoqi@0	56	assert(ZapUnusedHeapArea, "Mangling should not be in use");
aoqi@0	57	// Mangle between top and the high water mark. Safeguard
aoqi@0	58	// against the space changing since top_for_allocations was
aoqi@0	59	// set.
aoqi@0	60	HeapWord* mangled_end = MIN2(top_for_allocations(), end());
aoqi@0	61	if (top() < mangled_end) {
aoqi@0	62	MemRegion mangle_mr(top(), mangled_end);
aoqi@0	63	SpaceMangler::mangle_region(mangle_mr);
aoqi@0	64	// Light weight check of mangling.
aoqi@0	65	check_mangled_unused_area(end());
aoqi@0	66	}
aoqi@0	67	// Complete check of unused area which is functional when
aoqi@0	68	// DEBUG_MANGLING is defined.
aoqi@0	69	check_mangled_unused_area_complete();
aoqi@0	70	}
aoqi@0	71
aoqi@0	72	// A complete mangle is expected in the
aoqi@0	73	// exceptional case where top_for_allocations is not
aoqi@0	74	// properly tracking the high water mark for mangling.
aoqi@0	75	// This can be the case when to-space is being used for
aoqi@0	76	// scratch space during a mark-sweep-compact. See
aoqi@0	77	// contribute_scratch() and PSMarkSweep::allocate_stacks().
aoqi@0	78	void SpaceMangler::mangle_unused_area_complete() {
aoqi@0	79	assert(ZapUnusedHeapArea, "Mangling should not be in use");
aoqi@0	80	MemRegion mangle_mr(top(), end());
aoqi@0	81	SpaceMangler::mangle_region(mangle_mr);
aoqi@0	82	}
aoqi@0	83
aoqi@0	84	// Simply mangle the MemRegion mr.
aoqi@0	85	void SpaceMangler::mangle_region(MemRegion mr) {
aoqi@0	86	assert(ZapUnusedHeapArea, "Mangling should not be in use");
aoqi@0	87	#ifdef ASSERT
aoqi@0	88	if(TraceZapUnusedHeapArea) {
aoqi@0	89	gclog_or_tty->print("Mangling [0x%x to 0x%x)", mr.start(), mr.end());
aoqi@0	90	}
aoqi@0	91	Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord);
aoqi@0	92	if(TraceZapUnusedHeapArea) {
aoqi@0	93	gclog_or_tty->print_cr(" done");
aoqi@0	94	}
aoqi@0	95	#endif
aoqi@0	96	}
aoqi@0	97
aoqi@0	98	// Check that top, top_for_allocations and the last
aoqi@0	99	// word of the space are mangled. In a tight memory
aoqi@0	100	// situation even this light weight mangling could
aoqi@0	101	// cause paging by touching the end of the space.
aoqi@0	102	void SpaceMangler::check_mangled_unused_area(HeapWord* limit) {
aoqi@0	103	if (CheckZapUnusedHeapArea) {
aoqi@0	104	// This method can be called while the spaces are
aoqi@0	105	// being reshaped so skip the test if the end of the
aoqi@0	106	// space is beyond the specified limit;
aoqi@0	107	if (end() > limit) return;
aoqi@0	108
aoqi@0	109	assert(top() == end() ||
aoqi@0	110	(is_mangled(top())), "Top not mangled");
aoqi@0	111	assert((top_for_allocations() < top()) ||
aoqi@0	112	(top_for_allocations() >= end()) ||
aoqi@0	113	(is_mangled(top_for_allocations())),
aoqi@0	114	"Older unused not mangled");
aoqi@0	115	assert(top() == end() ||
aoqi@0	116	(is_mangled(end() - 1)), "End not properly mangled");
aoqi@0	117	// Only does checking when DEBUG_MANGLING is defined.
aoqi@0	118	check_mangled_unused_area_complete();
aoqi@0	119	}
aoqi@0	120	}
aoqi@0	121
aoqi@0	122	#undef DEBUG_MANGLING
aoqi@0	123	// This should only be used while debugging the mangling
aoqi@0	124	// because of the high cost of checking the completeness.
aoqi@0	125	void SpaceMangler::check_mangled_unused_area_complete() {
aoqi@0	126	if (CheckZapUnusedHeapArea) {
aoqi@0	127	assert(ZapUnusedHeapArea, "Not mangling unused area");
aoqi@0	128	#ifdef DEBUG_MANGLING
aoqi@0	129	HeapWord* q = top();
aoqi@0	130	HeapWord* limit = end();
aoqi@0	131
aoqi@0	132	bool passed = true;
aoqi@0	133	while (q < limit) {
aoqi@0	134	if (!is_mangled(q)) {
aoqi@0	135	passed = false;
aoqi@0	136	break;
aoqi@0	137	}
aoqi@0	138	q++;
aoqi@0	139	}
aoqi@0	140	assert(passed, "Mangling is not complete");
aoqi@0	141	#endif
aoqi@0	142	}
aoqi@0	143	}
aoqi@0	144	#undef DEBUG_MANGLING
aoqi@0	145	#endif // not PRODUCT