Mercurial > hg > graal-compiler
annotate src/share/vm/opto/indexSet.cpp @ 1722:effb55808a18
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author | johnc |
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date | Wed, 18 Aug 2010 17:44:33 -0400 |
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2 * Copyright (c) 1998, 2004, Oracle and/or its affiliates. All rights reserved. |
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5 * This code is free software; you can redistribute it and/or modify it | |
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12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
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15 * You should have received a copy of the GNU General Public License version | |
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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 | |
25 // This file defines the IndexSet class, a set of sparse integer indices. | |
26 // This data structure is used by the compiler in its liveness analysis and | |
27 // during register allocation. It also defines an iterator for this class. | |
28 | |
29 #include "incls/_precompiled.incl" | |
30 #include "incls/_indexSet.cpp.incl" | |
31 | |
32 //-------------------------------- Initializations ------------------------------ | |
33 | |
34 IndexSet::BitBlock IndexSet::_empty_block = IndexSet::BitBlock(); | |
35 | |
36 #ifdef ASSERT | |
37 // Initialize statistics counters | |
38 uint IndexSet::_alloc_new = 0; | |
39 uint IndexSet::_alloc_total = 0; | |
40 | |
41 long IndexSet::_total_bits = 0; | |
42 long IndexSet::_total_used_blocks = 0; | |
43 long IndexSet::_total_unused_blocks = 0; | |
44 | |
45 // Per set, or all sets operation tracing | |
46 int IndexSet::_serial_count = 1; | |
47 #endif | |
48 | |
49 // What is the first set bit in a 5 bit integer? | |
50 const byte IndexSetIterator::_first_bit[32] = { | |
51 0, 0, 1, 0, | |
52 2, 0, 1, 0, | |
53 3, 0, 1, 0, | |
54 2, 0, 1, 0, | |
55 4, 0, 1, 0, | |
56 2, 0, 1, 0, | |
57 3, 0, 1, 0, | |
58 2, 0, 1, 0 | |
59 }; | |
60 | |
61 // What is the second set bit in a 5 bit integer? | |
62 const byte IndexSetIterator::_second_bit[32] = { | |
63 5, 5, 5, 1, | |
64 5, 2, 2, 1, | |
65 5, 3, 3, 1, | |
66 3, 2, 2, 1, | |
67 5, 4, 4, 1, | |
68 4, 2, 2, 1, | |
69 4, 3, 3, 1, | |
70 3, 2, 2, 1 | |
71 }; | |
72 | |
73 // I tried implementing the IndexSetIterator with a window_size of 8 and | |
74 // didn't seem to get a noticeable speedup. I am leaving in the tables | |
75 // in case we want to switch back. | |
76 | |
77 /*const byte IndexSetIterator::_first_bit[256] = { | |
78 8, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
79 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
80 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
81 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, | |
82 6, 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 7, 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 6, 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 }; | |
95 | |
96 const byte IndexSetIterator::_second_bit[256] = { | |
97 8, 8, 8, 1, 8, 2, 2, 1, 8, 3, 3, 1, 3, 2, 2, 1, | |
98 8, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
99 8, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, | |
100 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
101 8, 6, 6, 1, 6, 2, 2, 1, 6, 3, 3, 1, 3, 2, 2, 1, | |
102 6, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
103 6, 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, 7, 7, 1, 7, 2, 2, 1, 7, 3, 3, 1, 3, 2, 2, 1, | |
106 7, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
107 7, 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 7, 6, 6, 1, 6, 2, 2, 1, 6, 3, 3, 1, 3, 2, 2, 1, | |
110 6, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1, | |
111 6, 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 };*/ | |
114 | |
115 //---------------------------- IndexSet::populate_free_list() ----------------------------- | |
116 // Populate the free BitBlock list with a batch of BitBlocks. The BitBlocks | |
117 // are 32 bit aligned. | |
118 | |
119 void IndexSet::populate_free_list() { | |
120 Compile *compile = Compile::current(); | |
121 BitBlock *free = (BitBlock*)compile->indexSet_free_block_list(); | |
122 | |
123 char *mem = (char*)arena()->Amalloc_4(sizeof(BitBlock) * | |
124 bitblock_alloc_chunk_size + 32); | |
125 | |
126 // Align the pointer to a 32 bit boundary. | |
127 BitBlock *new_blocks = (BitBlock*)(((uintptr_t)mem + 32) & ~0x001F); | |
128 | |
129 // Add the new blocks to the free list. | |
130 for (int i = 0; i < bitblock_alloc_chunk_size; i++) { | |
131 new_blocks->set_next(free); | |
132 free = new_blocks; | |
133 new_blocks++; | |
134 } | |
135 | |
136 compile->set_indexSet_free_block_list(free); | |
137 | |
138 #ifdef ASSERT | |
139 if (CollectIndexSetStatistics) { | |
140 _alloc_new += bitblock_alloc_chunk_size; | |
141 } | |
142 #endif | |
143 } | |
144 | |
145 | |
146 //---------------------------- IndexSet::alloc_block() ------------------------ | |
147 // Allocate a BitBlock from the free list. If the free list is empty, | |
148 // prime it. | |
149 | |
150 IndexSet::BitBlock *IndexSet::alloc_block() { | |
151 #ifdef ASSERT | |
152 if (CollectIndexSetStatistics) { | |
153 _alloc_total++; | |
154 } | |
155 #endif | |
156 Compile *compile = Compile::current(); | |
157 BitBlock* free_list = (BitBlock*)compile->indexSet_free_block_list(); | |
158 if (free_list == NULL) { | |
159 populate_free_list(); | |
160 free_list = (BitBlock*)compile->indexSet_free_block_list(); | |
161 } | |
162 BitBlock *block = free_list; | |
163 compile->set_indexSet_free_block_list(block->next()); | |
164 | |
165 block->clear(); | |
166 return block; | |
167 } | |
168 | |
169 //---------------------------- IndexSet::alloc_block_containing() ------------- | |
170 // Allocate a new BitBlock and put it into the position in the _blocks array | |
171 // corresponding to element. | |
172 | |
173 IndexSet::BitBlock *IndexSet::alloc_block_containing(uint element) { | |
174 BitBlock *block = alloc_block(); | |
175 uint bi = get_block_index(element); | |
176 _blocks[bi] = block; | |
177 return block; | |
178 } | |
179 | |
180 //---------------------------- IndexSet::free_block() ------------------------- | |
181 // Add a BitBlock to the free list. | |
182 | |
183 void IndexSet::free_block(uint i) { | |
184 debug_only(check_watch("free block", i)); | |
185 assert(i < _max_blocks, "block index too large"); | |
186 BitBlock *block = _blocks[i]; | |
187 assert(block != &_empty_block, "cannot free the empty block"); | |
188 block->set_next((IndexSet::BitBlock*)Compile::current()->indexSet_free_block_list()); | |
189 Compile::current()->set_indexSet_free_block_list(block); | |
190 set_block(i,&_empty_block); | |
191 } | |
192 | |
193 //------------------------------lrg_union-------------------------------------- | |
194 // Compute the union of all elements of one and two which interfere with | |
195 // the RegMask mask. If the degree of the union becomes exceeds | |
196 // fail_degree, the union bails out. The underlying set is cleared before | |
197 // the union is performed. | |
198 | |
199 uint IndexSet::lrg_union(uint lr1, uint lr2, | |
200 const uint fail_degree, | |
201 const PhaseIFG *ifg, | |
202 const RegMask &mask ) { | |
203 IndexSet *one = ifg->neighbors(lr1); | |
204 IndexSet *two = ifg->neighbors(lr2); | |
205 LRG &lrg1 = ifg->lrgs(lr1); | |
206 LRG &lrg2 = ifg->lrgs(lr2); | |
207 #ifdef ASSERT | |
208 assert(_max_elements == one->_max_elements, "max element mismatch"); | |
209 check_watch("union destination"); | |
210 one->check_watch("union source"); | |
211 two->check_watch("union source"); | |
212 #endif | |
213 | |
214 // Compute the degree of the combined live-range. The combined | |
215 // live-range has the union of the original live-ranges' neighbors set as | |
216 // well as the neighbors of all intermediate copies, minus those neighbors | |
217 // that can not use the intersected allowed-register-set. | |
218 | |
219 // Copy the larger set. Insert the smaller set into the larger. | |
220 if (two->count() > one->count()) { | |
221 IndexSet *temp = one; | |
222 one = two; | |
223 two = temp; | |
224 } | |
225 | |
226 clear(); | |
227 | |
228 // Used to compute degree of register-only interferences. Infinite-stack | |
229 // neighbors do not alter colorability, as they can always color to some | |
230 // other color. (A variant of the Briggs assertion) | |
231 uint reg_degree = 0; | |
232 | |
233 uint element; | |
234 // Load up the combined interference set with the neighbors of one | |
235 IndexSetIterator elements(one); | |
236 while ((element = elements.next()) != 0) { | |
237 LRG &lrg = ifg->lrgs(element); | |
238 if (mask.overlap(lrg.mask())) { | |
239 insert(element); | |
240 if( !lrg.mask().is_AllStack() ) { | |
241 reg_degree += lrg1.compute_degree(lrg); | |
242 if( reg_degree >= fail_degree ) return reg_degree; | |
243 } else { | |
244 // !!!!! Danger! No update to reg_degree despite having a neighbor. | |
245 // A variant of the Briggs assertion. | |
246 // Not needed if I simplify during coalesce, ala George/Appel. | |
247 assert( lrg.lo_degree(), "" ); | |
248 } | |
249 } | |
250 } | |
251 // Add neighbors of two as well | |
252 IndexSetIterator elements2(two); | |
253 while ((element = elements2.next()) != 0) { | |
254 LRG &lrg = ifg->lrgs(element); | |
255 if (mask.overlap(lrg.mask())) { | |
256 if (insert(element)) { | |
257 if( !lrg.mask().is_AllStack() ) { | |
258 reg_degree += lrg2.compute_degree(lrg); | |
259 if( reg_degree >= fail_degree ) return reg_degree; | |
260 } else { | |
261 // !!!!! Danger! No update to reg_degree despite having a neighbor. | |
262 // A variant of the Briggs assertion. | |
263 // Not needed if I simplify during coalesce, ala George/Appel. | |
264 assert( lrg.lo_degree(), "" ); | |
265 } | |
266 } | |
267 } | |
268 } | |
269 | |
270 return reg_degree; | |
271 } | |
272 | |
273 //---------------------------- IndexSet() ----------------------------- | |
274 // A deep copy constructor. This is used when you need a scratch copy of this set. | |
275 | |
276 IndexSet::IndexSet (IndexSet *set) { | |
277 #ifdef ASSERT | |
278 _serial_number = _serial_count++; | |
279 set->check_watch("copied", _serial_number); | |
280 check_watch("initialized by copy", set->_serial_number); | |
281 _max_elements = set->_max_elements; | |
282 #endif | |
283 _count = set->_count; | |
284 _max_blocks = set->_max_blocks; | |
285 if (_max_blocks <= preallocated_block_list_size) { | |
286 _blocks = _preallocated_block_list; | |
287 } else { | |
288 _blocks = | |
289 (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks); | |
290 } | |
291 for (uint i = 0; i < _max_blocks; i++) { | |
292 BitBlock *block = set->_blocks[i]; | |
293 if (block == &_empty_block) { | |
294 set_block(i, &_empty_block); | |
295 } else { | |
296 BitBlock *new_block = alloc_block(); | |
297 memcpy(new_block->words(), block->words(), sizeof(uint32) * words_per_block); | |
298 set_block(i, new_block); | |
299 } | |
300 } | |
301 } | |
302 | |
303 //---------------------------- IndexSet::initialize() ----------------------------- | |
304 // Prepare an IndexSet for use. | |
305 | |
306 void IndexSet::initialize(uint max_elements) { | |
307 #ifdef ASSERT | |
308 _serial_number = _serial_count++; | |
309 check_watch("initialized", max_elements); | |
310 _max_elements = max_elements; | |
311 #endif | |
312 _count = 0; | |
313 _max_blocks = (max_elements + bits_per_block - 1) / bits_per_block; | |
314 | |
315 if (_max_blocks <= preallocated_block_list_size) { | |
316 _blocks = _preallocated_block_list; | |
317 } else { | |
318 _blocks = (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks); | |
319 } | |
320 for (uint i = 0; i < _max_blocks; i++) { | |
321 set_block(i, &_empty_block); | |
322 } | |
323 } | |
324 | |
325 //---------------------------- IndexSet::initialize()------------------------------ | |
326 // Prepare an IndexSet for use. If it needs to allocate its _blocks array, it does | |
327 // so from the Arena passed as a parameter. BitBlock allocation is still done from | |
328 // the static Arena which was set with reset_memory(). | |
329 | |
330 void IndexSet::initialize(uint max_elements, Arena *arena) { | |
331 #ifdef ASSERT | |
332 _serial_number = _serial_count++; | |
333 check_watch("initialized2", max_elements); | |
334 _max_elements = max_elements; | |
335 #endif // ASSERT | |
336 _count = 0; | |
337 _max_blocks = (max_elements + bits_per_block - 1) / bits_per_block; | |
338 | |
339 if (_max_blocks <= preallocated_block_list_size) { | |
340 _blocks = _preallocated_block_list; | |
341 } else { | |
342 _blocks = (IndexSet::BitBlock**) arena->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks); | |
343 } | |
344 for (uint i = 0; i < _max_blocks; i++) { | |
345 set_block(i, &_empty_block); | |
346 } | |
347 } | |
348 | |
349 //---------------------------- IndexSet::swap() ----------------------------- | |
350 // Exchange two IndexSets. | |
351 | |
352 void IndexSet::swap(IndexSet *set) { | |
353 #ifdef ASSERT | |
354 assert(_max_elements == set->_max_elements, "must have same universe size to swap"); | |
355 check_watch("swap", set->_serial_number); | |
356 set->check_watch("swap", _serial_number); | |
357 #endif | |
358 | |
359 for (uint i = 0; i < _max_blocks; i++) { | |
360 BitBlock *temp = _blocks[i]; | |
361 set_block(i, set->_blocks[i]); | |
362 set->set_block(i, temp); | |
363 } | |
364 uint temp = _count; | |
365 _count = set->_count; | |
366 set->_count = temp; | |
367 } | |
368 | |
369 //---------------------------- IndexSet::dump() ----------------------------- | |
370 // Print this set. Used for debugging. | |
371 | |
372 #ifndef PRODUCT | |
373 void IndexSet::dump() const { | |
374 IndexSetIterator elements(this); | |
375 | |
376 tty->print("{"); | |
377 uint i; | |
378 while ((i = elements.next()) != 0) { | |
379 tty->print("L%d ", i); | |
380 } | |
381 tty->print_cr("}"); | |
382 } | |
383 #endif | |
384 | |
385 #ifdef ASSERT | |
386 //---------------------------- IndexSet::tally_iteration_statistics() ----------------------------- | |
387 // Update block/bit counts to reflect that this set has been iterated over. | |
388 | |
389 void IndexSet::tally_iteration_statistics() const { | |
390 _total_bits += count(); | |
391 | |
392 for (uint i = 0; i < _max_blocks; i++) { | |
393 if (_blocks[i] != &_empty_block) { | |
394 _total_used_blocks++; | |
395 } else { | |
396 _total_unused_blocks++; | |
397 } | |
398 } | |
399 } | |
400 | |
401 //---------------------------- IndexSet::print_statistics() ----------------------------- | |
402 // Print statistics about IndexSet usage. | |
403 | |
404 void IndexSet::print_statistics() { | |
405 long total_blocks = _total_used_blocks + _total_unused_blocks; | |
406 tty->print_cr ("Accumulated IndexSet usage statistics:"); | |
407 tty->print_cr ("--------------------------------------"); | |
408 tty->print_cr (" Iteration:"); | |
409 tty->print_cr (" blocks visited: %d", total_blocks); | |
410 tty->print_cr (" blocks empty: %4.2f%%", 100.0*_total_unused_blocks/total_blocks); | |
411 tty->print_cr (" bit density (bits/used blocks): %4.2f%%", (double)_total_bits/_total_used_blocks); | |
412 tty->print_cr (" bit density (bits/all blocks): %4.2f%%", (double)_total_bits/total_blocks); | |
413 tty->print_cr (" Allocation:"); | |
414 tty->print_cr (" blocks allocated: %d", _alloc_new); | |
415 tty->print_cr (" blocks used/reused: %d", _alloc_total); | |
416 } | |
417 | |
418 //---------------------------- IndexSet::verify() ----------------------------- | |
419 // Expensive test of IndexSet sanity. Ensure that the count agrees with the | |
420 // number of bits in the blocks. Make sure the iterator is seeing all elements | |
421 // of the set. Meant for use during development. | |
422 | |
423 void IndexSet::verify() const { | |
424 assert(!member(0), "zero cannot be a member"); | |
425 uint count = 0; | |
426 uint i; | |
427 for (i = 1; i < _max_elements; i++) { | |
428 if (member(i)) { | |
429 count++; | |
430 assert(count <= _count, "_count is messed up"); | |
431 } | |
432 } | |
433 | |
434 IndexSetIterator elements(this); | |
435 count = 0; | |
436 while ((i = elements.next()) != 0) { | |
437 count++; | |
438 assert(member(i), "returned a non member"); | |
439 assert(count <= _count, "iterator returned wrong number of elements"); | |
440 } | |
441 } | |
442 #endif | |
443 | |
444 //---------------------------- IndexSetIterator() ----------------------------- | |
445 // Create an iterator for a set. If empty blocks are detected when iterating | |
446 // over the set, these blocks are replaced. | |
447 | |
448 IndexSetIterator::IndexSetIterator(IndexSet *set) { | |
449 #ifdef ASSERT | |
450 if (CollectIndexSetStatistics) { | |
451 set->tally_iteration_statistics(); | |
452 } | |
453 set->check_watch("traversed", set->count()); | |
454 #endif | |
455 if (set->is_empty()) { | |
456 _current = 0; | |
457 _next_word = IndexSet::words_per_block; | |
458 _next_block = 1; | |
459 _max_blocks = 1; | |
460 | |
461 // We don't need the following values when we iterate over an empty set. | |
462 // The commented out code is left here to document that the omission | |
463 // is intentional. | |
464 // | |
465 //_value = 0; | |
466 //_words = NULL; | |
467 //_blocks = NULL; | |
468 //_set = NULL; | |
469 } else { | |
470 _current = 0; | |
471 _value = 0; | |
472 _next_block = 0; | |
473 _next_word = IndexSet::words_per_block; | |
474 | |
475 _max_blocks = set->_max_blocks; | |
476 _words = NULL; | |
477 _blocks = set->_blocks; | |
478 _set = set; | |
479 } | |
480 } | |
481 | |
482 //---------------------------- IndexSetIterator(const) ----------------------------- | |
483 // Iterate over a constant IndexSet. | |
484 | |
485 IndexSetIterator::IndexSetIterator(const IndexSet *set) { | |
486 #ifdef ASSERT | |
487 if (CollectIndexSetStatistics) { | |
488 set->tally_iteration_statistics(); | |
489 } | |
490 // We don't call check_watch from here to avoid bad recursion. | |
491 // set->check_watch("traversed const", set->count()); | |
492 #endif | |
493 if (set->is_empty()) { | |
494 _current = 0; | |
495 _next_word = IndexSet::words_per_block; | |
496 _next_block = 1; | |
497 _max_blocks = 1; | |
498 | |
499 // We don't need the following values when we iterate over an empty set. | |
500 // The commented out code is left here to document that the omission | |
501 // is intentional. | |
502 // | |
503 //_value = 0; | |
504 //_words = NULL; | |
505 //_blocks = NULL; | |
506 //_set = NULL; | |
507 } else { | |
508 _current = 0; | |
509 _value = 0; | |
510 _next_block = 0; | |
511 _next_word = IndexSet::words_per_block; | |
512 | |
513 _max_blocks = set->_max_blocks; | |
514 _words = NULL; | |
515 _blocks = set->_blocks; | |
516 _set = NULL; | |
517 } | |
518 } | |
519 | |
520 //---------------------------- List16Iterator::advance_and_next() ----------------------------- | |
521 // Advance to the next non-empty word in the set being iterated over. Return the next element | |
522 // if there is one. If we are done, return 0. This method is called from the next() method | |
523 // when it gets done with a word. | |
524 | |
525 uint IndexSetIterator::advance_and_next() { | |
526 // See if there is another non-empty word in the current block. | |
527 for (uint wi = _next_word; wi < (unsigned)IndexSet::words_per_block; wi++) { | |
528 if (_words[wi] != 0) { | |
529 // Found a non-empty word. | |
530 _value = ((_next_block - 1) * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word); | |
531 _current = _words[wi]; | |
532 | |
533 _next_word = wi+1; | |
534 | |
535 return next(); | |
536 } | |
537 } | |
538 | |
539 // We ran out of words in the current block. Advance to next non-empty block. | |
540 for (uint bi = _next_block; bi < _max_blocks; bi++) { | |
541 if (_blocks[bi] != &IndexSet::_empty_block) { | |
542 // Found a non-empty block. | |
543 | |
544 _words = _blocks[bi]->words(); | |
545 for (uint wi = 0; wi < (unsigned)IndexSet::words_per_block; wi++) { | |
546 if (_words[wi] != 0) { | |
547 // Found a non-empty word. | |
548 _value = (bi * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word); | |
549 _current = _words[wi]; | |
550 | |
551 _next_block = bi+1; | |
552 _next_word = wi+1; | |
553 | |
554 return next(); | |
555 } | |
556 } | |
557 | |
558 // All of the words in the block were empty. Replace | |
559 // the block with the empty block. | |
560 if (_set) { | |
561 _set->free_block(bi); | |
562 } | |
563 } | |
564 } | |
565 | |
566 // These assignments make redundant calls to next on a finished iterator | |
567 // faster. Probably not necessary. | |
568 _next_block = _max_blocks; | |
569 _next_word = IndexSet::words_per_block; | |
570 | |
571 // No more words. | |
572 return 0; | |
573 } |