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.
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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 "utilities/debug.hpp"
30
31 // Implements the common base functionality for arrays that contain provisions
32 // for accessing its elements using a biased index.
33 // The element type is defined by the instantiating the template.
34 class G1BiasedMappedArrayBase VALUE_OBJ_CLASS_SPEC {
35 friend class VMStructs;
36 public:
37 typedef size_t idx_t;
38 protected:
39 address _base; // the real base address
40 size_t _length; // the length of the array
41 address _biased_base; // base address biased by "bias" elements
42 size_t _bias; // the bias, i.e. the offset biased_base is located to the right in elements
43 uint _shift_by; // the amount of bits to shift right when mapping to an index of the array.
44
45 protected:
46
47 G1BiasedMappedArrayBase() : _base(NULL), _length(0), _biased_base(NULL),
48 _bias(0), _shift_by(0) { }
49
50 // Allocate a new array, generic version.
51 static address create_new_base_array(size_t length, size_t elem_size);
52
53 // Initialize the members of this class. The biased start address of this array
54 // is the bias (in elements) multiplied by the element size.
55 void initialize_base(address base, size_t length, size_t bias, size_t elem_size, uint shift_by) {
56 assert(base != NULL, "just checking");
57 assert(length > 0, "just checking");
58 assert(shift_by < sizeof(uintptr_t) * 8, err_msg("Shifting by %u, larger than word size?", shift_by));
59 _base = base;
60 _length = length;
61 _biased_base = base - (bias * elem_size);
62 _bias = bias;
63 _shift_by = shift_by;
64 }
65
66 // Allocate and initialize this array to cover the heap addresses in the range
67 // of [bottom, end).
68 void initialize(HeapWord* bottom, HeapWord* end, size_t target_elem_size_in_bytes, size_t mapping_granularity_in_bytes) {
69 assert(mapping_granularity_in_bytes > 0, "just checking");
70 assert(is_power_of_2(mapping_granularity_in_bytes),
71 err_msg("mapping granularity must be power of 2, is %zd", mapping_granularity_in_bytes));
72 assert((uintptr_t)bottom % mapping_granularity_in_bytes == 0,
73 err_msg("bottom mapping area address must be a multiple of mapping granularity %zd, is "PTR_FORMAT,
74 mapping_granularity_in_bytes, p2i(bottom)));
75 assert((uintptr_t)end % mapping_granularity_in_bytes == 0,
76 err_msg("end mapping area address must be a multiple of mapping granularity %zd, is "PTR_FORMAT,
77 mapping_granularity_in_bytes, p2i(end)));
78 size_t num_target_elems = pointer_delta(end, bottom, mapping_granularity_in_bytes);
79 idx_t bias = (uintptr_t)bottom / mapping_granularity_in_bytes;
80 address base = create_new_base_array(num_target_elems, target_elem_size_in_bytes);
81 initialize_base(base, num_target_elems, bias, target_elem_size_in_bytes, log2_intptr(mapping_granularity_in_bytes));
82 }
83
84 size_t bias() const { return _bias; }
85 uint shift_by() const { return _shift_by; }
86
87 void verify_index(idx_t index) const PRODUCT_RETURN;
88 void verify_biased_index(idx_t biased_index) const PRODUCT_RETURN;
89 void verify_biased_index_inclusive_end(idx_t biased_index) const PRODUCT_RETURN;
90
91 public:
92 // Return the length of the array in elements.
93 size_t length() const { return _length; }
94 };
95
96 // Array that provides biased access and mapping from (valid) addresses in the
97 // heap into this array.
98 template<class T>
99 class G1BiasedMappedArray : public G1BiasedMappedArrayBase {
100 public:
101 typedef G1BiasedMappedArrayBase::idx_t idx_t;
102
103 T* base() const { return (T*)G1BiasedMappedArrayBase::_base; }
104 // Return the element of the given array at the given index. Assume
105 // the index is valid. This is a convenience method that does sanity
106 // checking on the index.
107 T get_by_index(idx_t index) const {
108 verify_index(index);
109 return this->base()[index];
110 }
111
112 // Set the element of the given array at the given index to the
113 // given value. Assume the index is valid. This is a convenience
114 // method that does sanity checking on the index.
115 void set_by_index(idx_t index, T value) {
116 verify_index(index);
117 this->base()[index] = value;
118 }
119
120 // The raw biased base pointer.
121 T* biased_base() const { return (T*)G1BiasedMappedArrayBase::_biased_base; }
122
123 // Return the element of the given array that covers the given word in the
124 // heap. Assumes the index is valid.
125 T get_by_address(HeapWord* value) const {
126 idx_t biased_index = ((uintptr_t)value) >> this->shift_by();
127 this->verify_biased_index(biased_index);
128 return biased_base()[biased_index];
129 }
130
131 // Return the index of the element of the given array that covers the given
132 // word in the heap.
133 idx_t get_index_by_address(HeapWord* value) const {
134 idx_t biased_index = ((uintptr_t)value) >> this->shift_by();
135 this->verify_biased_index(biased_index);
136 return biased_index - _bias;
137 }
138
139 // Set the value of the array entry that corresponds to the given array.
140 void set_by_address(HeapWord * address, T value) {
141 idx_t biased_index = ((uintptr_t)address) >> this->shift_by();
142 this->verify_biased_index(biased_index);
143 biased_base()[biased_index] = value;
144 }
145
146 // Set the value of all array entries that correspond to addresses
147 // in the specified MemRegion.
148 void set_by_address(MemRegion range, T value) {
149 idx_t biased_start = ((uintptr_t)range.start()) >> this->shift_by();
150 idx_t biased_last = ((uintptr_t)range.last()) >> this->shift_by();
151 this->verify_biased_index(biased_start);
152 this->verify_biased_index(biased_last);
153 for (idx_t i = biased_start; i <= biased_last; i++) {
154 biased_base()[i] = value;
155 }
156 }
157
158 protected:
159 // Returns the address of the element the given address maps to
160 T* address_mapped_to(HeapWord* address) {
161 idx_t biased_index = ((uintptr_t)address) >> this->shift_by();
162 this->verify_biased_index_inclusive_end(biased_index);
163 return biased_base() + biased_index;
164 }
165
166 public:
167 // Return the smallest address (inclusive) in the heap that this array covers.
168 HeapWord* bottom_address_mapped() const {
169 return (HeapWord*) ((uintptr_t)this->bias() << this->shift_by());
170 }
171
172 // Return the highest address (exclusive) in the heap that this array covers.
173 HeapWord* end_address_mapped() const {
174 return (HeapWord*) ((uintptr_t)(this->bias() + this->length()) << this->shift_by());
175 }
176
177 protected:
178 virtual T default_value() const = 0;
179 // Set all elements of the given array to the given value.
180 void clear() {
181 T value = default_value();
182 for (idx_t i = 0; i < length(); i++) {
183 set_by_index(i, value);
184 }
185 }
186 public:
187 G1BiasedMappedArray() {}
188
189 // Allocate and initialize this array to cover the heap addresses in the range
190 // of [bottom, end).
191 void initialize(HeapWord* bottom, HeapWord* end, size_t mapping_granularity) {
192 G1BiasedMappedArrayBase::initialize(bottom, end, sizeof(T), mapping_granularity);
193 this->clear();
194 }
195 };
196
197 #endif // SHARE_VM_GC_G1_G1BIASEDARRAY_HPP