| /* |
| * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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| * |
| */ |
| |
| #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP |
| #define SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP |
| |
| #include "gc_implementation/g1/g1BiasedArray.hpp" |
| #include "memory/allocation.hpp" |
| |
| // Per-region state during garbage collection. |
| struct InCSetState { |
| public: |
| // We use different types to represent the state value. Particularly SPARC puts |
| // values in structs from "left to right", i.e. MSB to LSB. This results in many |
| // unnecessary shift operations when loading and storing values of this type. |
| // This degrades performance significantly (>10%) on that platform. |
| // Other tested ABIs do not seem to have this problem, and actually tend to |
| // favor smaller types, so we use the smallest usable type there. |
| #ifdef SPARC |
| #define CSETSTATE_FORMAT INTPTR_FORMAT |
| typedef intptr_t in_cset_state_t; |
| #else |
| #define CSETSTATE_FORMAT "%d" |
| typedef int8_t in_cset_state_t; |
| #endif |
| private: |
| in_cset_state_t _value; |
| public: |
| enum { |
| // Selection of the values were driven to micro-optimize the encoding and |
| // frequency of the checks. |
| // The most common check is whether the region is in the collection set or not. |
| // This encoding allows us to use an != 0 check which in some architectures |
| // (x86*) can be encoded slightly more efficently than a normal comparison |
| // against zero. |
| // The same situation occurs when checking whether the region is humongous |
| // or not, which is encoded by values < 0. |
| // The other values are simply encoded in increasing generation order, which |
| // makes getting the next generation fast by a simple increment. |
| Humongous = -1, // The region is humongous - note that actually any value < 0 would be possible here. |
| NotInCSet = 0, // The region is not in the collection set. |
| Young = 1, // The region is in the collection set and a young region. |
| Old = 2, // The region is in the collection set and an old region. |
| Num |
| }; |
| |
| InCSetState(in_cset_state_t value = NotInCSet) : _value(value) { |
| assert(is_valid(), err_msg("Invalid state %d", _value)); |
| } |
| |
| in_cset_state_t value() const { return _value; } |
| |
| void set_old() { _value = Old; } |
| |
| bool is_in_cset_or_humongous() const { return _value != NotInCSet; } |
| bool is_in_cset() const { return _value > NotInCSet; } |
| bool is_humongous() const { return _value < NotInCSet; } |
| bool is_young() const { return _value == Young; } |
| bool is_old() const { return _value == Old; } |
| |
| #ifdef ASSERT |
| bool is_default() const { return !is_in_cset_or_humongous(); } |
| bool is_valid() const { return (_value >= Humongous) && (_value < Num); } |
| bool is_valid_gen() const { return (_value >= Young && _value <= Old); } |
| #endif |
| }; |
| |
| // Instances of this class are used for quick tests on whether a reference points |
| // into the collection set and into which generation or is a humongous object |
| // |
| // Each of the array's elements indicates whether the corresponding region is in |
| // the collection set and if so in which generation, or a humongous region. |
| // |
| // We use this to speed up reference processing during young collection and |
| // quickly reclaim humongous objects. For the latter, by making a humongous region |
| // succeed this test, we sort-of add it to the collection set. During the reference |
| // iteration closures, when we see a humongous region, we then simply mark it as |
| // referenced, i.e. live. |
| class G1InCSetStateFastTestBiasedMappedArray : public G1BiasedMappedArray<InCSetState> { |
| protected: |
| InCSetState default_value() const { return InCSetState::NotInCSet; } |
| public: |
| void set_humongous(uintptr_t index) { |
| assert(get_by_index(index).is_default(), |
| err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value())); |
| set_by_index(index, InCSetState::Humongous); |
| } |
| |
| void clear_humongous(uintptr_t index) { |
| set_by_index(index, InCSetState::NotInCSet); |
| } |
| |
| void set_in_young(uintptr_t index) { |
| assert(get_by_index(index).is_default(), |
| err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value())); |
| set_by_index(index, InCSetState::Young); |
| } |
| |
| void set_in_old(uintptr_t index) { |
| assert(get_by_index(index).is_default(), |
| err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value())); |
| set_by_index(index, InCSetState::Old); |
| } |
| |
| bool is_in_cset_or_humongous(HeapWord* addr) const { return at(addr).is_in_cset_or_humongous(); } |
| bool is_in_cset(HeapWord* addr) const { return at(addr).is_in_cset(); } |
| InCSetState at(HeapWord* addr) const { return get_by_address(addr); } |
| void clear() { G1BiasedMappedArray<InCSetState>::clear(); } |
| }; |
| |
| #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP |