135 lines
5.9 KiB
C++
135 lines
5.9 KiB
C++
/*
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* Copyright (c) 2014, 2018, 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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#ifndef SHARE_VM_GC_G1_G1INCSETSTATE_HPP
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#define SHARE_VM_GC_G1_G1INCSETSTATE_HPP
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#include "gc/g1/g1BiasedArray.hpp"
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#include "gc/g1/heapRegion.hpp"
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// Per-region state during garbage collection.
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struct InCSetState {
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public:
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// We use different types to represent the state value. Particularly SPARC puts
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// values in structs from "left to right", i.e. MSB to LSB. This results in many
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// unnecessary shift operations when loading and storing values of this type.
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// This degrades performance significantly (>10%) on that platform.
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// Other tested ABIs do not seem to have this problem, and actually tend to
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// favor smaller types, so we use the smallest usable type there.
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#ifdef SPARC
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#define CSETSTATE_FORMAT INTPTR_FORMAT
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typedef intptr_t in_cset_state_t;
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#else
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#define CSETSTATE_FORMAT "%d"
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typedef int8_t in_cset_state_t;
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#endif
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private:
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in_cset_state_t _value;
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public:
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enum {
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// Selection of the values were driven to micro-optimize the encoding and
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// frequency of the checks.
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// The most common check is whether the region is in the collection set or not,
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// this encoding allows us to use an > 0 check.
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// The positive values are encoded in increasing generation order, which
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// makes getting the next generation fast by a simple increment. They are also
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// used to index into arrays.
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// The negative values are used for objects requiring various special cases,
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// for example eager reclamation of humongous objects.
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Humongous = -1, // The region is humongous
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NotInCSet = 0, // The region is not in the collection set.
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Young = 1, // The region is in the collection set and a young region.
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Old = 2, // The region is in the collection set and an old region.
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Num
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};
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InCSetState(in_cset_state_t value = NotInCSet) : _value(value) {
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assert(is_valid(), "Invalid state %d", _value);
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}
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in_cset_state_t value() const { return _value; }
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void set_old() { _value = Old; }
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bool is_in_cset_or_humongous() const { return is_in_cset() || is_humongous(); }
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bool is_in_cset() const { return _value > NotInCSet; }
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bool is_humongous() const { return _value == Humongous; }
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bool is_young() const { return _value == Young; }
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bool is_old() const { return _value == Old; }
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#ifdef ASSERT
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bool is_default() const { return _value == NotInCSet; }
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bool is_valid() const { return (_value >= Humongous) && (_value < Num); }
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bool is_valid_gen() const { return (_value >= Young && _value <= Old); }
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#endif
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};
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// Instances of this class are used for quick tests on whether a reference points
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// into the collection set and into which generation or is a humongous object
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//
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// Each of the array's elements indicates whether the corresponding region is in
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// the collection set and if so in which generation, or a humongous region.
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//
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// We use this to speed up reference processing during young collection and
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// quickly reclaim humongous objects. For the latter, by making a humongous region
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// succeed this test, we sort-of add it to the collection set. During the reference
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// iteration closures, when we see a humongous region, we then simply mark it as
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// referenced, i.e. live.
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class G1InCSetStateFastTestBiasedMappedArray : public G1BiasedMappedArray<InCSetState> {
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protected:
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InCSetState default_value() const { return InCSetState::NotInCSet; }
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public:
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void set_humongous(uintptr_t index) {
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assert(get_by_index(index).is_default(),
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"State at index " INTPTR_FORMAT " should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value());
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set_by_index(index, InCSetState::Humongous);
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}
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void clear_humongous(uintptr_t index) {
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set_by_index(index, InCSetState::NotInCSet);
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}
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void set_in_young(uintptr_t index) {
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assert(get_by_index(index).is_default(),
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"State at index " INTPTR_FORMAT " should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value());
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set_by_index(index, InCSetState::Young);
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}
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void set_in_old(uintptr_t index) {
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assert(get_by_index(index).is_default(),
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"State at index " INTPTR_FORMAT " should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value());
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set_by_index(index, InCSetState::Old);
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}
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bool is_in_cset_or_humongous(HeapWord* addr) const { return at(addr).is_in_cset_or_humongous(); }
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bool is_in_cset(HeapWord* addr) const { return at(addr).is_in_cset(); }
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bool is_in_cset(const HeapRegion* hr) const { return get_by_index(hr->hrm_index()).is_in_cset(); }
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InCSetState at(HeapWord* addr) const { return get_by_address(addr); }
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void clear() { G1BiasedMappedArray<InCSetState>::clear(); }
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void clear(const HeapRegion* hr) { return set_by_index(hr->hrm_index(), InCSetState::NotInCSet); }
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};
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#endif // SHARE_VM_GC_G1_G1INCSETSTATE_HPP
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