Tue, 18 Jul 2017 09:53:54 +0200
8184762: ZapStackSegments should use optimized memset
Reviewed-by: rkennke, mgerdin
1 /*
2 * Copyright (c) 2009, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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
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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
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23 */
25 #ifndef SHARE_VM_UTILITIES_STACK_INLINE_HPP
26 #define SHARE_VM_UTILITIES_STACK_INLINE_HPP
28 #include "utilities/stack.hpp"
29 #include "utilities/copy.hpp"
31 template <MEMFLAGS F> StackBase<F>::StackBase(size_t segment_size, size_t max_cache_size,
32 size_t max_size):
33 _seg_size(segment_size),
34 _max_cache_size(max_cache_size),
35 _max_size(adjust_max_size(max_size, segment_size))
36 {
37 assert(_max_size % _seg_size == 0, "not a multiple");
38 }
40 template <MEMFLAGS F> size_t StackBase<F>::adjust_max_size(size_t max_size, size_t seg_size)
41 {
42 assert(seg_size > 0, "cannot be 0");
43 assert(max_size >= seg_size || max_size == 0, "max_size too small");
44 const size_t limit = max_uintx - (seg_size - 1);
45 if (max_size == 0 || max_size > limit) {
46 max_size = limit;
47 }
48 return (max_size + seg_size - 1) / seg_size * seg_size;
49 }
51 template <class E, MEMFLAGS F>
52 Stack<E, F>::Stack(size_t segment_size, size_t max_cache_size, size_t max_size):
53 StackBase<F>(adjust_segment_size(segment_size), max_cache_size, max_size)
54 {
55 reset(true);
56 }
58 template <class E, MEMFLAGS F>
59 void Stack<E, F>::push(E item)
60 {
61 assert(!is_full(), "pushing onto a full stack");
62 if (this->_cur_seg_size == this->_seg_size) {
63 push_segment();
64 }
65 this->_cur_seg[this->_cur_seg_size] = item;
66 ++this->_cur_seg_size;
67 }
69 template <class E, MEMFLAGS F>
70 E Stack<E, F>::pop()
71 {
72 assert(!is_empty(), "popping from an empty stack");
73 if (this->_cur_seg_size == 1) {
74 E tmp = _cur_seg[--this->_cur_seg_size];
75 pop_segment();
76 return tmp;
77 }
78 return this->_cur_seg[--this->_cur_seg_size];
79 }
81 template <class E, MEMFLAGS F>
82 void Stack<E, F>::clear(bool clear_cache)
83 {
84 free_segments(_cur_seg);
85 if (clear_cache) free_segments(_cache);
86 reset(clear_cache);
87 }
89 template <class E, MEMFLAGS F>
90 size_t Stack<E, F>::adjust_segment_size(size_t seg_size)
91 {
92 const size_t elem_sz = sizeof(E);
93 const size_t ptr_sz = sizeof(E*);
94 assert(elem_sz % ptr_sz == 0 || ptr_sz % elem_sz == 0, "bad element size");
95 if (elem_sz < ptr_sz) {
96 return align_size_up(seg_size * elem_sz, ptr_sz) / elem_sz;
97 }
98 return seg_size;
99 }
101 template <class E, MEMFLAGS F>
102 size_t Stack<E, F>::link_offset() const
103 {
104 return align_size_up(this->_seg_size * sizeof(E), sizeof(E*));
105 }
107 template <class E, MEMFLAGS F>
108 size_t Stack<E, F>::segment_bytes() const
109 {
110 return link_offset() + sizeof(E*);
111 }
113 template <class E, MEMFLAGS F>
114 E** Stack<E, F>::link_addr(E* seg) const
115 {
116 return (E**) ((char*)seg + link_offset());
117 }
119 template <class E, MEMFLAGS F>
120 E* Stack<E, F>::get_link(E* seg) const
121 {
122 return *link_addr(seg);
123 }
125 template <class E, MEMFLAGS F>
126 E* Stack<E, F>::set_link(E* new_seg, E* old_seg)
127 {
128 *link_addr(new_seg) = old_seg;
129 return new_seg;
130 }
132 template <class E, MEMFLAGS F>
133 E* Stack<E, F>::alloc(size_t bytes)
134 {
135 return (E*) NEW_C_HEAP_ARRAY(char, bytes, F);
136 }
138 template <class E, MEMFLAGS F>
139 void Stack<E, F>::free(E* addr, size_t bytes)
140 {
141 FREE_C_HEAP_ARRAY(char, (char*) addr, F);
142 }
144 template <class E, MEMFLAGS F>
145 void Stack<E, F>::push_segment()
146 {
147 assert(this->_cur_seg_size == this->_seg_size, "current segment is not full");
148 E* next;
149 if (this->_cache_size > 0) {
150 // Use a cached segment.
151 next = _cache;
152 _cache = get_link(_cache);
153 --this->_cache_size;
154 } else {
155 next = alloc(segment_bytes());
156 DEBUG_ONLY(zap_segment(next, true);)
157 }
158 const bool at_empty_transition = is_empty();
159 this->_cur_seg = set_link(next, _cur_seg);
160 this->_cur_seg_size = 0;
161 this->_full_seg_size += at_empty_transition ? 0 : this->_seg_size;
162 DEBUG_ONLY(verify(at_empty_transition);)
163 }
165 template <class E, MEMFLAGS F>
166 void Stack<E, F>::pop_segment()
167 {
168 assert(this->_cur_seg_size == 0, "current segment is not empty");
169 E* const prev = get_link(_cur_seg);
170 if (this->_cache_size < this->_max_cache_size) {
171 // Add the current segment to the cache.
172 DEBUG_ONLY(zap_segment(_cur_seg, false);)
173 _cache = set_link(_cur_seg, _cache);
174 ++this->_cache_size;
175 } else {
176 DEBUG_ONLY(zap_segment(_cur_seg, true);)
177 free(_cur_seg, segment_bytes());
178 }
179 const bool at_empty_transition = prev == NULL;
180 this->_cur_seg = prev;
181 this->_cur_seg_size = this->_seg_size;
182 this->_full_seg_size -= at_empty_transition ? 0 : this->_seg_size;
183 DEBUG_ONLY(verify(at_empty_transition);)
184 }
186 template <class E, MEMFLAGS F>
187 void Stack<E, F>::free_segments(E* seg)
188 {
189 const size_t bytes = segment_bytes();
190 while (seg != NULL) {
191 E* const prev = get_link(seg);
192 free(seg, bytes);
193 seg = prev;
194 }
195 }
197 template <class E, MEMFLAGS F>
198 void Stack<E, F>::reset(bool reset_cache)
199 {
200 this->_cur_seg_size = this->_seg_size; // So push() will alloc a new segment.
201 this->_full_seg_size = 0;
202 _cur_seg = NULL;
203 if (reset_cache) {
204 this->_cache_size = 0;
205 _cache = NULL;
206 }
207 }
209 #ifdef ASSERT
210 template <class E, MEMFLAGS F>
211 void Stack<E, F>::verify(bool at_empty_transition) const
212 {
213 assert(size() <= this->max_size(), "stack exceeded bounds");
214 assert(this->cache_size() <= this->max_cache_size(), "cache exceeded bounds");
215 assert(this->_cur_seg_size <= this->segment_size(), "segment index exceeded bounds");
217 assert(this->_full_seg_size % this->_seg_size == 0, "not a multiple");
218 assert(at_empty_transition || is_empty() == (size() == 0), "mismatch");
219 assert((_cache == NULL) == (this->cache_size() == 0), "mismatch");
221 if (is_empty()) {
222 assert(this->_cur_seg_size == this->segment_size(), "sanity");
223 }
224 }
226 template <class E, MEMFLAGS F>
227 void Stack<E, F>::zap_segment(E* seg, bool zap_link_field) const
228 {
229 if (!ZapStackSegments) return;
230 const size_t zap_bytes = segment_bytes() - (zap_link_field ? 0 : sizeof(E*));
231 Copy::fill_to_bytes(seg, zap_bytes, badStackSegVal);
232 }
233 #endif
235 template <class E, MEMFLAGS F>
236 E* ResourceStack<E, F>::alloc(size_t bytes)
237 {
238 return (E*) resource_allocate_bytes(bytes);
239 }
241 template <class E, MEMFLAGS F>
242 void ResourceStack<E, F>::free(E* addr, size_t bytes)
243 {
244 resource_free_bytes((char*) addr, bytes);
245 }
247 template <class E, MEMFLAGS F>
248 void StackIterator<E, F>::sync()
249 {
250 _full_seg_size = _stack._full_seg_size;
251 _cur_seg_size = _stack._cur_seg_size;
252 _cur_seg = _stack._cur_seg;
253 }
255 template <class E, MEMFLAGS F>
256 E* StackIterator<E, F>::next_addr()
257 {
258 assert(!is_empty(), "no items left");
259 if (_cur_seg_size == 1) {
260 E* addr = _cur_seg;
261 _cur_seg = _stack.get_link(_cur_seg);
262 _cur_seg_size = _stack.segment_size();
263 _full_seg_size -= _stack.segment_size();
264 return addr;
265 }
266 return _cur_seg + --_cur_seg_size;
267 }
269 #endif // SHARE_VM_UTILITIES_STACK_INLINE_HPP