1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/g1/g1InCSetState.hpp Fri Dec 19 09:21:06 2014 +0100
1.3 @@ -0,0 +1,132 @@
1.4 +/*
1.5 + * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP
1.29 +#define SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP
1.30 +
1.31 +#include "gc_implementation/g1/g1BiasedArray.hpp"
1.32 +#include "memory/allocation.hpp"
1.33 +
1.34 +// Per-region state during garbage collection.
1.35 +struct InCSetState {
1.36 + public:
1.37 + // We use different types to represent the state value. Particularly SPARC puts
1.38 + // values in structs from "left to right", i.e. MSB to LSB. This results in many
1.39 + // unnecessary shift operations when loading and storing values of this type.
1.40 + // This degrades performance significantly (>10%) on that platform.
1.41 + // Other tested ABIs do not seem to have this problem, and actually tend to
1.42 + // favor smaller types, so we use the smallest usable type there.
1.43 +#ifdef SPARC
1.44 + #define CSETSTATE_FORMAT INTPTR_FORMAT
1.45 + typedef intptr_t in_cset_state_t;
1.46 +#else
1.47 + #define CSETSTATE_FORMAT "%d"
1.48 + typedef int8_t in_cset_state_t;
1.49 +#endif
1.50 + private:
1.51 + in_cset_state_t _value;
1.52 + public:
1.53 + enum {
1.54 + // Selection of the values were driven to micro-optimize the encoding and
1.55 + // frequency of the checks.
1.56 + // The most common check is whether the region is in the collection set or not.
1.57 + // This encoding allows us to use an != 0 check which in some architectures
1.58 + // (x86*) can be encoded slightly more efficently than a normal comparison
1.59 + // against zero.
1.60 + // The same situation occurs when checking whether the region is humongous
1.61 + // or not, which is encoded by values < 0.
1.62 + // The other values are simply encoded in increasing generation order, which
1.63 + // makes getting the next generation fast by a simple increment.
1.64 + Humongous = -1, // The region is humongous - note that actually any value < 0 would be possible here.
1.65 + NotInCSet = 0, // The region is not in the collection set.
1.66 + Young = 1, // The region is in the collection set and a young region.
1.67 + Old = 2, // The region is in the collection set and an old region.
1.68 + Num
1.69 + };
1.70 +
1.71 + InCSetState(in_cset_state_t value = NotInCSet) : _value(value) {
1.72 + assert(is_valid(), err_msg("Invalid state %d", _value));
1.73 + }
1.74 +
1.75 + in_cset_state_t value() const { return _value; }
1.76 +
1.77 + void set_old() { _value = Old; }
1.78 +
1.79 + bool is_in_cset_or_humongous() const { return _value != NotInCSet; }
1.80 + bool is_in_cset() const { return _value > NotInCSet; }
1.81 + bool is_humongous() const { return _value < NotInCSet; }
1.82 + bool is_young() const { return _value == Young; }
1.83 + bool is_old() const { return _value == Old; }
1.84 +
1.85 +#ifdef ASSERT
1.86 + bool is_default() const { return !is_in_cset_or_humongous(); }
1.87 + bool is_valid() const { return (_value >= Humongous) && (_value < Num); }
1.88 + bool is_valid_gen() const { return (_value >= Young && _value <= Old); }
1.89 +#endif
1.90 +};
1.91 +
1.92 +// Instances of this class are used for quick tests on whether a reference points
1.93 +// into the collection set and into which generation or is a humongous object
1.94 +//
1.95 +// Each of the array's elements indicates whether the corresponding region is in
1.96 +// the collection set and if so in which generation, or a humongous region.
1.97 +//
1.98 +// We use this to speed up reference processing during young collection and
1.99 +// quickly reclaim humongous objects. For the latter, by making a humongous region
1.100 +// succeed this test, we sort-of add it to the collection set. During the reference
1.101 +// iteration closures, when we see a humongous region, we then simply mark it as
1.102 +// referenced, i.e. live.
1.103 +class G1InCSetStateFastTestBiasedMappedArray : public G1BiasedMappedArray<InCSetState> {
1.104 + protected:
1.105 + InCSetState default_value() const { return InCSetState::NotInCSet; }
1.106 + public:
1.107 + void set_humongous(uintptr_t index) {
1.108 + assert(get_by_index(index).is_default(),
1.109 + err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()));
1.110 + set_by_index(index, InCSetState::Humongous);
1.111 + }
1.112 +
1.113 + void clear_humongous(uintptr_t index) {
1.114 + set_by_index(index, InCSetState::NotInCSet);
1.115 + }
1.116 +
1.117 + void set_in_young(uintptr_t index) {
1.118 + assert(get_by_index(index).is_default(),
1.119 + err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()));
1.120 + set_by_index(index, InCSetState::Young);
1.121 + }
1.122 +
1.123 + void set_in_old(uintptr_t index) {
1.124 + assert(get_by_index(index).is_default(),
1.125 + err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()));
1.126 + set_by_index(index, InCSetState::Old);
1.127 + }
1.128 +
1.129 + bool is_in_cset_or_humongous(HeapWord* addr) const { return at(addr).is_in_cset_or_humongous(); }
1.130 + bool is_in_cset(HeapWord* addr) const { return at(addr).is_in_cset(); }
1.131 + InCSetState at(HeapWord* addr) const { return get_by_address(addr); }
1.132 + void clear() { G1BiasedMappedArray<InCSetState>::clear(); }
1.133 +};
1.134 +
1.135 +#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP
