1 /*
2 * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_VM_GC_G1_G1BIASEDARRAY_HPP
26 #define SHARE_VM_GC_G1_G1BIASEDARRAY_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "utilities/debug.hpp"
31
32 // Implements the common base functionality for arrays that contain provisions
33 // for accessing its elements using a biased index.
34 // The element type is defined by the instantiating the template.
35 class G1BiasedMappedArrayBase VALUE_OBJ_CLASS_SPEC {
36 friend class VMStructs;
37 public:
38 typedef size_t idx_t;
39 protected:
40 address _base; // the real base address
41 size_t _length; // the length of the array
42 address _biased_base; // base address biased by "bias" elements
43 size_t _bias; // the bias, i.e. the offset biased_base is located to the right in elements
44 uint _shift_by; // the amount of bits to shift right when mapping to an index of the array.
45
46 protected:
47
48 G1BiasedMappedArrayBase() : _base(NULL), _length(0), _biased_base(NULL),
49 _bias(0), _shift_by(0) { }
50
51 // Allocate a new array, generic version.
52 static address create_new_base_array(size_t length, size_t elem_size);
53
54 // Initialize the members of this class. The biased start address of this array
55 // is the bias (in elements) multiplied by the element size.
56 void initialize_base(address base, size_t length, size_t bias, size_t elem_size, uint shift_by) {
57 assert(base != NULL, "just checking");
58 assert(length > 0, "just checking");
59 assert(shift_by < sizeof(uintptr_t) * 8, "Shifting by %u, larger than word size?", shift_by);
60 _base = base;
61 _length = length;
62 _biased_base = base - (bias * elem_size);
63 _bias = bias;
64 _shift_by = shift_by;
65 }
66
67 // Allocate and initialize this array to cover the heap addresses in the range
68 // of [bottom, end).
69 void initialize(HeapWord* bottom, HeapWord* end, size_t target_elem_size_in_bytes, size_t mapping_granularity_in_bytes) {
70 assert(mapping_granularity_in_bytes > 0, "just checking");
71 assert(is_power_of_2(mapping_granularity_in_bytes),
72 "mapping granularity must be power of 2, is %zd", mapping_granularity_in_bytes);
73 assert((uintptr_t)bottom % mapping_granularity_in_bytes == 0,
74 "bottom mapping area address must be a multiple of mapping granularity %zd, is " PTR_FORMAT,
75 mapping_granularity_in_bytes, p2i(bottom));
76 assert((uintptr_t)end % mapping_granularity_in_bytes == 0,
77 "end mapping area address must be a multiple of mapping granularity %zd, is " PTR_FORMAT,
78 mapping_granularity_in_bytes, p2i(end));
79 size_t num_target_elems = pointer_delta(end, bottom, mapping_granularity_in_bytes);
80 idx_t bias = (uintptr_t)bottom / mapping_granularity_in_bytes;
81 address base = create_new_base_array(num_target_elems, target_elem_size_in_bytes);
82 initialize_base(base, num_target_elems, bias, target_elem_size_in_bytes, log2_intptr(mapping_granularity_in_bytes));
83 }
84
85 size_t bias() const { return _bias; }
86 uint shift_by() const { return _shift_by; }
87
88 void verify_index(idx_t index) const PRODUCT_RETURN;
89 void verify_biased_index(idx_t biased_index) const PRODUCT_RETURN;
90 void verify_biased_index_inclusive_end(idx_t biased_index) const PRODUCT_RETURN;
91
92 public:
93 // Return the length of the array in elements.
94 size_t length() const { return _length; }
95 };
96
97 // Array that provides biased access and mapping from (valid) addresses in the
98 // heap into this array.
99 template<class T>
100 class G1BiasedMappedArray : public G1BiasedMappedArrayBase {
101 public:
102 typedef G1BiasedMappedArrayBase::idx_t idx_t;
103
104 T* base() const { return (T*)G1BiasedMappedArrayBase::_base; }
105 // Return the element of the given array at the given index. Assume
106 // the index is valid. This is a convenience method that does sanity
107 // checking on the index.
108 T get_by_index(idx_t index) const {
109 verify_index(index);
110 return this->base()[index];
111 }
112
113 // Set the element of the given array at the given index to the
114 // given value. Assume the index is valid. This is a convenience
115 // method that does sanity checking on the index.
116 void set_by_index(idx_t index, T value) {
117 verify_index(index);
118 this->base()[index] = value;
119 }
120
121 // The raw biased base pointer.
122 T* biased_base() const { return (T*)G1BiasedMappedArrayBase::_biased_base; }
123
124 // Return the element of the given array that covers the given word in the
125 // heap. Assumes the index is valid.
126 T get_by_address(HeapWord* value) const {
127 idx_t biased_index = ((uintptr_t)value) >> this->shift_by();
128 this->verify_biased_index(biased_index);
129 return biased_base()[biased_index];
130 }
131
132 // Return the index of the element of the given array that covers the given
133 // word in the heap.
134 idx_t get_index_by_address(HeapWord* value) const {
135 idx_t biased_index = ((uintptr_t)value) >> this->shift_by();
136 this->verify_biased_index(biased_index);
137 return biased_index - _bias;
138 }
139
140 // Set the value of the array entry that corresponds to the given array.
141 void set_by_address(HeapWord * address, T value) {
142 idx_t biased_index = ((uintptr_t)address) >> this->shift_by();
143 this->verify_biased_index(biased_index);
144 biased_base()[biased_index] = value;
145 }
146
147 // Set the value of all array entries that correspond to addresses
148 // in the specified MemRegion.
149 void set_by_address(MemRegion range, T value) {
150 idx_t biased_start = ((uintptr_t)range.start()) >> this->shift_by();
151 idx_t biased_last = ((uintptr_t)range.last()) >> this->shift_by();
152 this->verify_biased_index(biased_start);
153 this->verify_biased_index(biased_last);
154 for (idx_t i = biased_start; i <= biased_last; i++) {
155 biased_base()[i] = value;
156 }
157 }
158
159 protected:
160 // Returns the address of the element the given address maps to
161 T* address_mapped_to(HeapWord* address) {
162 idx_t biased_index = ((uintptr_t)address) >> this->shift_by();
163 this->verify_biased_index_inclusive_end(biased_index);
164 return biased_base() + biased_index;
165 }
166
167 public:
168 // Return the smallest address (inclusive) in the heap that this array covers.
169 HeapWord* bottom_address_mapped() const {
170 return (HeapWord*) ((uintptr_t)this->bias() << this->shift_by());
171 }
172
173 // Return the highest address (exclusive) in the heap that this array covers.
174 HeapWord* end_address_mapped() const {
175 return (HeapWord*) ((uintptr_t)(this->bias() + this->length()) << this->shift_by());
176 }
177
178 protected:
179 virtual T default_value() const = 0;
180 // Set all elements of the given array to the given value.
181 void clear() {
182 T value = default_value();
183 for (idx_t i = 0; i < length(); i++) {
184 set_by_index(i, value);
185 }
186 }
187 public:
188 G1BiasedMappedArray() {}
189
190 // Allocate and initialize this array to cover the heap addresses in the range
191 // of [bottom, end).
192 void initialize(HeapWord* bottom, HeapWord* end, size_t mapping_granularity) {
193 G1BiasedMappedArrayBase::initialize(bottom, end, sizeof(T), mapping_granularity);
194 this->clear();
195 }
196 };
197
198 #endif // SHARE_VM_GC_G1_G1BIASEDARRAY_HPP