1 /*
2 * Copyright (c) 2013, 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
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1BIASEDARRAY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1BIASEDARRAY_HPP
27
28 #include "utilities/debug.hpp"
29 #include "memory/allocation.inline.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 assert(length > 0, "just checking");
53 assert(elem_size > 0, "just checking");
54 return NEW_C_HEAP_ARRAY(u_char, length * elem_size, mtGC);
55 }
56
57 // Initialize the members of this class. The biased start address of this array
58 // is the bias (in elements) multiplied by the element size.
59 void initialize_base(address base, size_t length, size_t bias, size_t elem_size, uint shift_by) {
60 assert(base != NULL, "just checking");
61 assert(length > 0, "just checking");
62 assert(shift_by < sizeof(uintptr_t) * 8, err_msg("Shifting by %zd, larger than word size?", shift_by));
63 _base = base;
64 _length = length;
65 _biased_base = base - (bias * elem_size);
66 _bias = bias;
67 _shift_by = shift_by;
68 }
69
70 // Allocate and initialize this array to cover the heap addresses in the range
71 // of [bottom, end).
72 void initialize(HeapWord* bottom, HeapWord* end, size_t target_elem_size_in_bytes, size_t mapping_granularity_in_bytes) {
73 assert(mapping_granularity_in_bytes > 0, "just checking");
74 assert(is_power_of_2(mapping_granularity_in_bytes),
75 err_msg("mapping granularity must be power of 2, is %zd", mapping_granularity_in_bytes));
76 assert((uintptr_t)bottom % mapping_granularity_in_bytes == 0,
77 err_msg("bottom mapping area address must be a multiple of mapping granularity %zd, is "PTR_FORMAT,
78 mapping_granularity_in_bytes, bottom));
79 assert((uintptr_t)end % mapping_granularity_in_bytes == 0,
80 err_msg("end mapping area address must be a multiple of mapping granularity %zd, is "PTR_FORMAT,
81 mapping_granularity_in_bytes, end));
82 size_t num_target_elems = (end - bottom) / (mapping_granularity_in_bytes / HeapWordSize);
83 idx_t bias = (uintptr_t)bottom / mapping_granularity_in_bytes;
84 address base = create_new_base_array(num_target_elems, target_elem_size_in_bytes);
85 initialize_base(base, num_target_elems, bias, target_elem_size_in_bytes, log2_intptr(mapping_granularity_in_bytes));
86 }
87
88 size_t bias() const { return _bias; }
89 uint shift_by() const { return _shift_by; }
90
91 void verify_index(idx_t index) const PRODUCT_RETURN;
92 void verify_biased_index(idx_t biased_index) const PRODUCT_RETURN;
93 void verify_biased_index_inclusive_end(idx_t biased_index) const PRODUCT_RETURN;
94
95 public:
96 // Return the length of the array in elements.
97 size_t length() const { return _length; }
98 };
99
100 // Array that provides biased access and mapping from (valid) addresses in the
101 // heap into this array.
102 template<class T>
103 class G1BiasedMappedArray : public G1BiasedMappedArrayBase {
104 public:
105 typedef G1BiasedMappedArrayBase::idx_t idx_t;
106
107 T* base() const { return (T*)G1BiasedMappedArrayBase::_base; }
108 // Return the element of the given array at the given index. Assume
109 // the index is valid. This is a convenience method that does sanity
110 // checking on the index.
111 T get_by_index(idx_t index) const {
112 verify_index(index);
113 return this->base()[index];
114 }
115
116 // Set the element of the given array at the given index to the
117 // given value. Assume the index is valid. This is a convenience
118 // method that does sanity checking on the index.
119 void set_by_index(idx_t index, T value) {
120 verify_index(index);
121 this->base()[index] = value;
122 }
123
124 // The raw biased base pointer.
125 T* biased_base() const { return (T*)G1BiasedMappedArrayBase::_biased_base; }
126
127 // Return the element of the given array that covers the given word in the
128 // heap. Assumes the index is valid.
129 T get_by_address(HeapWord* value) const {
130 idx_t biased_index = ((uintptr_t)value) >> this->shift_by();
131 this->verify_biased_index(biased_index);
132 return biased_base()[biased_index];
133 }
134
135 // Set the value of the array entry that corresponds to the given array.
136 void set_by_address(HeapWord * address, T value) {
137 idx_t biased_index = ((uintptr_t)address) >> this->shift_by();
138 this->verify_biased_index(biased_index);
139 biased_base()[biased_index] = value;
140 }
141
142 protected:
143 // Returns the address of the element the given address maps to
144 T* address_mapped_to(HeapWord* address) {
145 idx_t biased_index = ((uintptr_t)address) >> this->shift_by();
146 this->verify_biased_index_inclusive_end(biased_index);
147 return biased_base() + biased_index;
148 }
149
150 public:
151 // Return the smallest address (inclusive) in the heap that this array covers.
152 HeapWord* bottom_address_mapped() const {
153 return (HeapWord*) ((uintptr_t)this->bias() << this->shift_by());
154 }
155
156 // Return the highest address (exclusive) in the heap that this array covers.
157 HeapWord* end_address_mapped() const {
158 return (HeapWord*) ((uintptr_t)(this->bias() + this->length()) << this->shift_by());
159 }
160
161 protected:
162 virtual T default_value() const = 0;
163 // Set all elements of the given array to the given value.
164 void clear() {
165 T value = default_value();
166 for (idx_t i = 0; i < length(); i++) {
167 set_by_index(i, value);
168 }
169 }
170 public:
171 G1BiasedMappedArray() {}
172
173 // Allocate and initialize this array to cover the heap addresses in the range
174 // of [bottom, end).
175 void initialize(HeapWord* bottom, HeapWord* end, size_t mapping_granularity) {
176 G1BiasedMappedArrayBase::initialize(bottom, end, sizeof(T), mapping_granularity);
177 this->clear();
178 }
179 };
180
181 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1BIASEDARRAY_HPP