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annotate src/share/vm/opto/indexSet.cpp @ 5274:e72dd6533eb9
documented importance of nmethod::_graal_compiled_method wrt code unloading and GC
author | Doug Simon <doug.simon@oracle.com> |
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date | Mon, 23 Apr 2012 15:42:30 +0200 |
parents | f7de3327c683 |
children |
rev | line source |
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0 | 1 /* |
2250 | 2 * Copyright (c) 1998, 2011, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
1552
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "memory/allocation.inline.hpp" | |
27 #include "opto/chaitin.hpp" | |
28 #include "opto/compile.hpp" | |
29 #include "opto/indexSet.hpp" | |
30 #include "opto/regmask.hpp" | |
31 | |
0 | 32 // This file defines the IndexSet class, a set of sparse integer indices. |
33 // This data structure is used by the compiler in its liveness analysis and | |
34 // during register allocation. It also defines an iterator for this class. | |
35 | |
36 //-------------------------------- Initializations ------------------------------ | |
37 | |
38 IndexSet::BitBlock IndexSet::_empty_block = IndexSet::BitBlock(); | |
39 | |
40 #ifdef ASSERT | |
41 // Initialize statistics counters | |
2250 | 42 julong IndexSet::_alloc_new = 0; |
43 julong IndexSet::_alloc_total = 0; | |
0 | 44 |
2250 | 45 julong IndexSet::_total_bits = 0; |
46 julong IndexSet::_total_used_blocks = 0; | |
47 julong IndexSet::_total_unused_blocks = 0; | |
0 | 48 |
49 // Per set, or all sets operation tracing | |
50 int IndexSet::_serial_count = 1; | |
51 #endif | |
52 | |
53 // What is the first set bit in a 5 bit integer? | |
54 const byte IndexSetIterator::_first_bit[32] = { | |
55 0, 0, 1, 0, | |
56 2, 0, 1, 0, | |
57 3, 0, 1, 0, | |
58 2, 0, 1, 0, | |
59 4, 0, 1, 0, | |
60 2, 0, 1, 0, | |
61 3, 0, 1, 0, | |
62 2, 0, 1, 0 | |
63 }; | |
64 | |
65 // What is the second set bit in a 5 bit integer? | |
66 const byte IndexSetIterator::_second_bit[32] = { | |
67 5, 5, 5, 1, | |
68 5, 2, 2, 1, | |
69 5, 3, 3, 1, | |
70 3, 2, 2, 1, | |
71 5, 4, 4, 1, | |
72 4, 2, 2, 1, | |
73 4, 3, 3, 1, | |
74 3, 2, 2, 1 | |
75 }; | |
76 | |
77 // I tried implementing the IndexSetIterator with a window_size of 8 and | |
78 // didn't seem to get a noticeable speedup. I am leaving in the tables | |
79 // in case we want to switch back. | |
80 | |
81 /*const byte IndexSetIterator::_first_bit[256] = { | |
82 8, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
83 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
84 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
85 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
86 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
87 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
88 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
89 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
90 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
91 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
92 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
93 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
94 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
95 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
96 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
97 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0 | |
98 }; | |
99 | |
100 const byte IndexSetIterator::_second_bit[256] = { | |
101 8, 8, 8, 1, 8, 2, 2, 1, 8, 3, 3, 1, 3, 2, 2, 1, | |
102 8, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
103 8, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, | |
104 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
105 8, 6, 6, 1, 6, 2, 2, 1, 6, 3, 3, 1, 3, 2, 2, 1, | |
106 6, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
107 6, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, | |
108 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
109 8, 7, 7, 1, 7, 2, 2, 1, 7, 3, 3, 1, 3, 2, 2, 1, | |
110 7, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
111 7, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, | |
112 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
113 7, 6, 6, 1, 6, 2, 2, 1, 6, 3, 3, 1, 3, 2, 2, 1, | |
114 6, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
115 6, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, | |
116 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1 | |
117 };*/ | |
118 | |
119 //---------------------------- IndexSet::populate_free_list() ----------------------------- | |
120 // Populate the free BitBlock list with a batch of BitBlocks. The BitBlocks | |
121 // are 32 bit aligned. | |
122 | |
123 void IndexSet::populate_free_list() { | |
124 Compile *compile = Compile::current(); | |
125 BitBlock *free = (BitBlock*)compile->indexSet_free_block_list(); | |
126 | |
127 char *mem = (char*)arena()->Amalloc_4(sizeof(BitBlock) * | |
128 bitblock_alloc_chunk_size + 32); | |
129 | |
130 // Align the pointer to a 32 bit boundary. | |
131 BitBlock *new_blocks = (BitBlock*)(((uintptr_t)mem + 32) & ~0x001F); | |
132 | |
133 // Add the new blocks to the free list. | |
134 for (int i = 0; i < bitblock_alloc_chunk_size; i++) { | |
135 new_blocks->set_next(free); | |
136 free = new_blocks; | |
137 new_blocks++; | |
138 } | |
139 | |
140 compile->set_indexSet_free_block_list(free); | |
141 | |
142 #ifdef ASSERT | |
143 if (CollectIndexSetStatistics) { | |
2250 | 144 inc_stat_counter(&_alloc_new, bitblock_alloc_chunk_size); |
0 | 145 } |
146 #endif | |
147 } | |
148 | |
149 | |
150 //---------------------------- IndexSet::alloc_block() ------------------------ | |
151 // Allocate a BitBlock from the free list. If the free list is empty, | |
152 // prime it. | |
153 | |
154 IndexSet::BitBlock *IndexSet::alloc_block() { | |
155 #ifdef ASSERT | |
156 if (CollectIndexSetStatistics) { | |
2250 | 157 inc_stat_counter(&_alloc_total, 1); |
0 | 158 } |
159 #endif | |
160 Compile *compile = Compile::current(); | |
161 BitBlock* free_list = (BitBlock*)compile->indexSet_free_block_list(); | |
162 if (free_list == NULL) { | |
163 populate_free_list(); | |
164 free_list = (BitBlock*)compile->indexSet_free_block_list(); | |
165 } | |
166 BitBlock *block = free_list; | |
167 compile->set_indexSet_free_block_list(block->next()); | |
168 | |
169 block->clear(); | |
170 return block; | |
171 } | |
172 | |
173 //---------------------------- IndexSet::alloc_block_containing() ------------- | |
174 // Allocate a new BitBlock and put it into the position in the _blocks array | |
175 // corresponding to element. | |
176 | |
177 IndexSet::BitBlock *IndexSet::alloc_block_containing(uint element) { | |
178 BitBlock *block = alloc_block(); | |
179 uint bi = get_block_index(element); | |
180 _blocks[bi] = block; | |
181 return block; | |
182 } | |
183 | |
184 //---------------------------- IndexSet::free_block() ------------------------- | |
185 // Add a BitBlock to the free list. | |
186 | |
187 void IndexSet::free_block(uint i) { | |
188 debug_only(check_watch("free block", i)); | |
189 assert(i < _max_blocks, "block index too large"); | |
190 BitBlock *block = _blocks[i]; | |
191 assert(block != &_empty_block, "cannot free the empty block"); | |
192 block->set_next((IndexSet::BitBlock*)Compile::current()->indexSet_free_block_list()); | |
193 Compile::current()->set_indexSet_free_block_list(block); | |
194 set_block(i,&_empty_block); | |
195 } | |
196 | |
197 //------------------------------lrg_union-------------------------------------- | |
198 // Compute the union of all elements of one and two which interfere with | |
199 // the RegMask mask. If the degree of the union becomes exceeds | |
200 // fail_degree, the union bails out. The underlying set is cleared before | |
201 // the union is performed. | |
202 | |
203 uint IndexSet::lrg_union(uint lr1, uint lr2, | |
204 const uint fail_degree, | |
205 const PhaseIFG *ifg, | |
206 const RegMask &mask ) { | |
207 IndexSet *one = ifg->neighbors(lr1); | |
208 IndexSet *two = ifg->neighbors(lr2); | |
209 LRG &lrg1 = ifg->lrgs(lr1); | |
210 LRG &lrg2 = ifg->lrgs(lr2); | |
211 #ifdef ASSERT | |
212 assert(_max_elements == one->_max_elements, "max element mismatch"); | |
213 check_watch("union destination"); | |
214 one->check_watch("union source"); | |
215 two->check_watch("union source"); | |
216 #endif | |
217 | |
218 // Compute the degree of the combined live-range. The combined | |
219 // live-range has the union of the original live-ranges' neighbors set as | |
220 // well as the neighbors of all intermediate copies, minus those neighbors | |
221 // that can not use the intersected allowed-register-set. | |
222 | |
223 // Copy the larger set. Insert the smaller set into the larger. | |
224 if (two->count() > one->count()) { | |
225 IndexSet *temp = one; | |
226 one = two; | |
227 two = temp; | |
228 } | |
229 | |
230 clear(); | |
231 | |
232 // Used to compute degree of register-only interferences. Infinite-stack | |
233 // neighbors do not alter colorability, as they can always color to some | |
234 // other color. (A variant of the Briggs assertion) | |
235 uint reg_degree = 0; | |
236 | |
237 uint element; | |
238 // Load up the combined interference set with the neighbors of one | |
239 IndexSetIterator elements(one); | |
240 while ((element = elements.next()) != 0) { | |
241 LRG &lrg = ifg->lrgs(element); | |
242 if (mask.overlap(lrg.mask())) { | |
243 insert(element); | |
244 if( !lrg.mask().is_AllStack() ) { | |
245 reg_degree += lrg1.compute_degree(lrg); | |
246 if( reg_degree >= fail_degree ) return reg_degree; | |
247 } else { | |
248 // !!!!! Danger! No update to reg_degree despite having a neighbor. | |
249 // A variant of the Briggs assertion. | |
250 // Not needed if I simplify during coalesce, ala George/Appel. | |
251 assert( lrg.lo_degree(), "" ); | |
252 } | |
253 } | |
254 } | |
255 // Add neighbors of two as well | |
256 IndexSetIterator elements2(two); | |
257 while ((element = elements2.next()) != 0) { | |
258 LRG &lrg = ifg->lrgs(element); | |
259 if (mask.overlap(lrg.mask())) { | |
260 if (insert(element)) { | |
261 if( !lrg.mask().is_AllStack() ) { | |
262 reg_degree += lrg2.compute_degree(lrg); | |
263 if( reg_degree >= fail_degree ) return reg_degree; | |
264 } else { | |
265 // !!!!! Danger! No update to reg_degree despite having a neighbor. | |
266 // A variant of the Briggs assertion. | |
267 // Not needed if I simplify during coalesce, ala George/Appel. | |
268 assert( lrg.lo_degree(), "" ); | |
269 } | |
270 } | |
271 } | |
272 } | |
273 | |
274 return reg_degree; | |
275 } | |
276 | |
277 //---------------------------- IndexSet() ----------------------------- | |
278 // A deep copy constructor. This is used when you need a scratch copy of this set. | |
279 | |
280 IndexSet::IndexSet (IndexSet *set) { | |
281 #ifdef ASSERT | |
282 _serial_number = _serial_count++; | |
283 set->check_watch("copied", _serial_number); | |
284 check_watch("initialized by copy", set->_serial_number); | |
285 _max_elements = set->_max_elements; | |
286 #endif | |
287 _count = set->_count; | |
288 _max_blocks = set->_max_blocks; | |
289 if (_max_blocks <= preallocated_block_list_size) { | |
290 _blocks = _preallocated_block_list; | |
291 } else { | |
292 _blocks = | |
293 (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks); | |
294 } | |
295 for (uint i = 0; i < _max_blocks; i++) { | |
296 BitBlock *block = set->_blocks[i]; | |
297 if (block == &_empty_block) { | |
298 set_block(i, &_empty_block); | |
299 } else { | |
300 BitBlock *new_block = alloc_block(); | |
301 memcpy(new_block->words(), block->words(), sizeof(uint32) * words_per_block); | |
302 set_block(i, new_block); | |
303 } | |
304 } | |
305 } | |
306 | |
307 //---------------------------- IndexSet::initialize() ----------------------------- | |
308 // Prepare an IndexSet for use. | |
309 | |
310 void IndexSet::initialize(uint max_elements) { | |
311 #ifdef ASSERT | |
312 _serial_number = _serial_count++; | |
313 check_watch("initialized", max_elements); | |
314 _max_elements = max_elements; | |
315 #endif | |
316 _count = 0; | |
317 _max_blocks = (max_elements + bits_per_block - 1) / bits_per_block; | |
318 | |
319 if (_max_blocks <= preallocated_block_list_size) { | |
320 _blocks = _preallocated_block_list; | |
321 } else { | |
322 _blocks = (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks); | |
323 } | |
324 for (uint i = 0; i < _max_blocks; i++) { | |
325 set_block(i, &_empty_block); | |
326 } | |
327 } | |
328 | |
329 //---------------------------- IndexSet::initialize()------------------------------ | |
330 // Prepare an IndexSet for use. If it needs to allocate its _blocks array, it does | |
331 // so from the Arena passed as a parameter. BitBlock allocation is still done from | |
332 // the static Arena which was set with reset_memory(). | |
333 | |
334 void IndexSet::initialize(uint max_elements, Arena *arena) { | |
335 #ifdef ASSERT | |
336 _serial_number = _serial_count++; | |
337 check_watch("initialized2", max_elements); | |
338 _max_elements = max_elements; | |
339 #endif // ASSERT | |
340 _count = 0; | |
341 _max_blocks = (max_elements + bits_per_block - 1) / bits_per_block; | |
342 | |
343 if (_max_blocks <= preallocated_block_list_size) { | |
344 _blocks = _preallocated_block_list; | |
345 } else { | |
346 _blocks = (IndexSet::BitBlock**) arena->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks); | |
347 } | |
348 for (uint i = 0; i < _max_blocks; i++) { | |
349 set_block(i, &_empty_block); | |
350 } | |
351 } | |
352 | |
353 //---------------------------- IndexSet::swap() ----------------------------- | |
354 // Exchange two IndexSets. | |
355 | |
356 void IndexSet::swap(IndexSet *set) { | |
357 #ifdef ASSERT | |
358 assert(_max_elements == set->_max_elements, "must have same universe size to swap"); | |
359 check_watch("swap", set->_serial_number); | |
360 set->check_watch("swap", _serial_number); | |
361 #endif | |
362 | |
363 for (uint i = 0; i < _max_blocks; i++) { | |
364 BitBlock *temp = _blocks[i]; | |
365 set_block(i, set->_blocks[i]); | |
366 set->set_block(i, temp); | |
367 } | |
368 uint temp = _count; | |
369 _count = set->_count; | |
370 set->_count = temp; | |
371 } | |
372 | |
373 //---------------------------- IndexSet::dump() ----------------------------- | |
374 // Print this set. Used for debugging. | |
375 | |
376 #ifndef PRODUCT | |
377 void IndexSet::dump() const { | |
378 IndexSetIterator elements(this); | |
379 | |
380 tty->print("{"); | |
381 uint i; | |
382 while ((i = elements.next()) != 0) { | |
383 tty->print("L%d ", i); | |
384 } | |
385 tty->print_cr("}"); | |
386 } | |
387 #endif | |
388 | |
389 #ifdef ASSERT | |
390 //---------------------------- IndexSet::tally_iteration_statistics() ----------------------------- | |
391 // Update block/bit counts to reflect that this set has been iterated over. | |
392 | |
393 void IndexSet::tally_iteration_statistics() const { | |
2250 | 394 inc_stat_counter(&_total_bits, count()); |
0 | 395 |
396 for (uint i = 0; i < _max_blocks; i++) { | |
397 if (_blocks[i] != &_empty_block) { | |
2250 | 398 inc_stat_counter(&_total_used_blocks, 1); |
0 | 399 } else { |
2250 | 400 inc_stat_counter(&_total_unused_blocks, 1); |
0 | 401 } |
402 } | |
403 } | |
404 | |
405 //---------------------------- IndexSet::print_statistics() ----------------------------- | |
406 // Print statistics about IndexSet usage. | |
407 | |
408 void IndexSet::print_statistics() { | |
2250 | 409 julong total_blocks = _total_used_blocks + _total_unused_blocks; |
0 | 410 tty->print_cr ("Accumulated IndexSet usage statistics:"); |
411 tty->print_cr ("--------------------------------------"); | |
412 tty->print_cr (" Iteration:"); | |
2250 | 413 tty->print_cr (" blocks visited: " UINT64_FORMAT, total_blocks); |
414 tty->print_cr (" blocks empty: %4.2f%%", 100.0*(double)_total_unused_blocks/total_blocks); | |
415 tty->print_cr (" bit density (bits/used blocks): %4.2f", (double)_total_bits/_total_used_blocks); | |
416 tty->print_cr (" bit density (bits/all blocks): %4.2f", (double)_total_bits/total_blocks); | |
0 | 417 tty->print_cr (" Allocation:"); |
2250 | 418 tty->print_cr (" blocks allocated: " UINT64_FORMAT, _alloc_new); |
419 tty->print_cr (" blocks used/reused: " UINT64_FORMAT, _alloc_total); | |
0 | 420 } |
421 | |
422 //---------------------------- IndexSet::verify() ----------------------------- | |
423 // Expensive test of IndexSet sanity. Ensure that the count agrees with the | |
424 // number of bits in the blocks. Make sure the iterator is seeing all elements | |
425 // of the set. Meant for use during development. | |
426 | |
427 void IndexSet::verify() const { | |
428 assert(!member(0), "zero cannot be a member"); | |
429 uint count = 0; | |
430 uint i; | |
431 for (i = 1; i < _max_elements; i++) { | |
432 if (member(i)) { | |
433 count++; | |
434 assert(count <= _count, "_count is messed up"); | |
435 } | |
436 } | |
437 | |
438 IndexSetIterator elements(this); | |
439 count = 0; | |
440 while ((i = elements.next()) != 0) { | |
441 count++; | |
442 assert(member(i), "returned a non member"); | |
443 assert(count <= _count, "iterator returned wrong number of elements"); | |
444 } | |
445 } | |
446 #endif | |
447 | |
448 //---------------------------- IndexSetIterator() ----------------------------- | |
449 // Create an iterator for a set. If empty blocks are detected when iterating | |
450 // over the set, these blocks are replaced. | |
451 | |
452 IndexSetIterator::IndexSetIterator(IndexSet *set) { | |
453 #ifdef ASSERT | |
454 if (CollectIndexSetStatistics) { | |
455 set->tally_iteration_statistics(); | |
456 } | |
457 set->check_watch("traversed", set->count()); | |
458 #endif | |
459 if (set->is_empty()) { | |
460 _current = 0; | |
461 _next_word = IndexSet::words_per_block; | |
462 _next_block = 1; | |
463 _max_blocks = 1; | |
464 | |
465 // We don't need the following values when we iterate over an empty set. | |
466 // The commented out code is left here to document that the omission | |
467 // is intentional. | |
468 // | |
469 //_value = 0; | |
470 //_words = NULL; | |
471 //_blocks = NULL; | |
472 //_set = NULL; | |
473 } else { | |
474 _current = 0; | |
475 _value = 0; | |
476 _next_block = 0; | |
477 _next_word = IndexSet::words_per_block; | |
478 | |
479 _max_blocks = set->_max_blocks; | |
480 _words = NULL; | |
481 _blocks = set->_blocks; | |
482 _set = set; | |
483 } | |
484 } | |
485 | |
486 //---------------------------- IndexSetIterator(const) ----------------------------- | |
487 // Iterate over a constant IndexSet. | |
488 | |
489 IndexSetIterator::IndexSetIterator(const IndexSet *set) { | |
490 #ifdef ASSERT | |
491 if (CollectIndexSetStatistics) { | |
492 set->tally_iteration_statistics(); | |
493 } | |
494 // We don't call check_watch from here to avoid bad recursion. | |
495 // set->check_watch("traversed const", set->count()); | |
496 #endif | |
497 if (set->is_empty()) { | |
498 _current = 0; | |
499 _next_word = IndexSet::words_per_block; | |
500 _next_block = 1; | |
501 _max_blocks = 1; | |
502 | |
503 // We don't need the following values when we iterate over an empty set. | |
504 // The commented out code is left here to document that the omission | |
505 // is intentional. | |
506 // | |
507 //_value = 0; | |
508 //_words = NULL; | |
509 //_blocks = NULL; | |
510 //_set = NULL; | |
511 } else { | |
512 _current = 0; | |
513 _value = 0; | |
514 _next_block = 0; | |
515 _next_word = IndexSet::words_per_block; | |
516 | |
517 _max_blocks = set->_max_blocks; | |
518 _words = NULL; | |
519 _blocks = set->_blocks; | |
520 _set = NULL; | |
521 } | |
522 } | |
523 | |
524 //---------------------------- List16Iterator::advance_and_next() ----------------------------- | |
525 // Advance to the next non-empty word in the set being iterated over. Return the next element | |
526 // if there is one. If we are done, return 0. This method is called from the next() method | |
527 // when it gets done with a word. | |
528 | |
529 uint IndexSetIterator::advance_and_next() { | |
530 // See if there is another non-empty word in the current block. | |
531 for (uint wi = _next_word; wi < (unsigned)IndexSet::words_per_block; wi++) { | |
532 if (_words[wi] != 0) { | |
533 // Found a non-empty word. | |
534 _value = ((_next_block - 1) * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word); | |
535 _current = _words[wi]; | |
536 | |
537 _next_word = wi+1; | |
538 | |
539 return next(); | |
540 } | |
541 } | |
542 | |
543 // We ran out of words in the current block. Advance to next non-empty block. | |
544 for (uint bi = _next_block; bi < _max_blocks; bi++) { | |
545 if (_blocks[bi] != &IndexSet::_empty_block) { | |
546 // Found a non-empty block. | |
547 | |
548 _words = _blocks[bi]->words(); | |
549 for (uint wi = 0; wi < (unsigned)IndexSet::words_per_block; wi++) { | |
550 if (_words[wi] != 0) { | |
551 // Found a non-empty word. | |
552 _value = (bi * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word); | |
553 _current = _words[wi]; | |
554 | |
555 _next_block = bi+1; | |
556 _next_word = wi+1; | |
557 | |
558 return next(); | |
559 } | |
560 } | |
561 | |
562 // All of the words in the block were empty. Replace | |
563 // the block with the empty block. | |
564 if (_set) { | |
565 _set->free_block(bi); | |
566 } | |
567 } | |
568 } | |
569 | |
570 // These assignments make redundant calls to next on a finished iterator | |
571 // faster. Probably not necessary. | |
572 _next_block = _max_blocks; | |
573 _next_word = IndexSet::words_per_block; | |
574 | |
575 // No more words. | |
576 return 0; | |
577 } |