--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/g1InCSetState.hpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2014, 2015, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_G1_G1INCSETSTATE_HPP
+#define SHARE_VM_GC_G1_G1INCSETSTATE_HPP
+
+#include "gc/g1/g1BiasedArray.hpp"
+#include "gc/g1/heapRegion.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(); }
+ bool is_in_cset(const HeapRegion* hr) const { return get_by_index(hr->hrm_index()).is_in_cset(); }
+ InCSetState at(HeapWord* addr) const { return get_by_address(addr); }
+ void clear() { G1BiasedMappedArray<InCSetState>::clear(); }
+ void clear(const HeapRegion* hr) { return set_by_index(hr->hrm_index(), InCSetState::NotInCSet); }
+};
+
+#endif // SHARE_VM_GC_G1_G1INCSETSTATE_HPP