1/*
2 * Copyright (c) 1998, 2018, 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.
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23 */
24
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
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
38IndexSet::BitBlock IndexSet::_empty_block = IndexSet::BitBlock();
39
40#ifdef ASSERT
41// Initialize statistics counters
42julong IndexSet::_alloc_new = 0;
43julong IndexSet::_alloc_total = 0;
44
45julong IndexSet::_total_bits = 0;
46julong IndexSet::_total_used_blocks = 0;
47julong IndexSet::_total_unused_blocks = 0;
48
49// Per set, or all sets operation tracing
50int IndexSet::_serial_count = 1;
51#endif
52
53//---------------------------- IndexSet::populate_free_list() -----------------------------
54// Populate the free BitBlock list with a batch of BitBlocks. The BitBlocks
55// are 32 bit aligned.
56
57void IndexSet::populate_free_list() {
58 Compile *compile = Compile::current();
59 BitBlock *free = (BitBlock*)compile->indexSet_free_block_list();
60
61 char *mem = (char*)arena()->Amalloc_4(sizeof(BitBlock) *
62 bitblock_alloc_chunk_size + 32);
63
64 // Align the pointer to a 32 bit boundary.
65 BitBlock *new_blocks = (BitBlock*)(((uintptr_t)mem + 32) & ~0x001F);
66
67 // Add the new blocks to the free list.
68 for (int i = 0; i < bitblock_alloc_chunk_size; i++) {
69 new_blocks->set_next(free);
70 free = new_blocks;
71 new_blocks++;
72 }
73
74 compile->set_indexSet_free_block_list(free);
75
76#ifdef ASSERT
77 if (CollectIndexSetStatistics) {
78 inc_stat_counter(&_alloc_new, bitblock_alloc_chunk_size);
79 }
80#endif
81}
82
83
84//---------------------------- IndexSet::alloc_block() ------------------------
85// Allocate a BitBlock from the free list. If the free list is empty,
86// prime it.
87
88IndexSet::BitBlock *IndexSet::alloc_block() {
89#ifdef ASSERT
90 if (CollectIndexSetStatistics) {
91 inc_stat_counter(&_alloc_total, 1);
92 }
93#endif
94 Compile *compile = Compile::current();
95 BitBlock* free_list = (BitBlock*)compile->indexSet_free_block_list();
96 if (free_list == NULL) {
97 populate_free_list();
98 free_list = (BitBlock*)compile->indexSet_free_block_list();
99 }
100 BitBlock *block = free_list;
101 compile->set_indexSet_free_block_list(block->next());
102
103 block->clear();
104 return block;
105}
106
107//---------------------------- IndexSet::alloc_block_containing() -------------
108// Allocate a new BitBlock and put it into the position in the _blocks array
109// corresponding to element.
110
111IndexSet::BitBlock *IndexSet::alloc_block_containing(uint element) {
112 BitBlock *block = alloc_block();
113 uint bi = get_block_index(element);
114 _blocks[bi] = block;
115 return block;
116}
117
118//---------------------------- IndexSet::free_block() -------------------------
119// Add a BitBlock to the free list.
120
121void IndexSet::free_block(uint i) {
122 debug_only(check_watch("free block", i));
123 assert(i < _max_blocks, "block index too large");
124 BitBlock *block = _blocks[i];
125 assert(block != &_empty_block, "cannot free the empty block");
126 block->set_next((IndexSet::BitBlock*)Compile::current()->indexSet_free_block_list());
127 Compile::current()->set_indexSet_free_block_list(block);
128 set_block(i,&_empty_block);
129}
130
131//------------------------------lrg_union--------------------------------------
132// Compute the union of all elements of one and two which interfere with
133// the RegMask mask. If the degree of the union becomes exceeds
134// fail_degree, the union bails out. The underlying set is cleared before
135// the union is performed.
136
137uint IndexSet::lrg_union(uint lr1, uint lr2,
138 const uint fail_degree,
139 const PhaseIFG *ifg,
140 const RegMask &mask ) {
141 IndexSet *one = ifg->neighbors(lr1);
142 IndexSet *two = ifg->neighbors(lr2);
143 LRG &lrg1 = ifg->lrgs(lr1);
144 LRG &lrg2 = ifg->lrgs(lr2);
145#ifdef ASSERT
146 assert(_max_elements == one->_max_elements, "max element mismatch");
147 check_watch("union destination");
148 one->check_watch("union source");
149 two->check_watch("union source");
150#endif
151
152 // Compute the degree of the combined live-range. The combined
153 // live-range has the union of the original live-ranges' neighbors set as
154 // well as the neighbors of all intermediate copies, minus those neighbors
155 // that can not use the intersected allowed-register-set.
156
157 // Copy the larger set. Insert the smaller set into the larger.
158 if (two->count() > one->count()) {
159 IndexSet *temp = one;
160 one = two;
161 two = temp;
162 }
163
164 clear();
165
166 // Used to compute degree of register-only interferences. Infinite-stack
167 // neighbors do not alter colorability, as they can always color to some
168 // other color. (A variant of the Briggs assertion)
169 uint reg_degree = 0;
170
171 uint element;
172 // Load up the combined interference set with the neighbors of one
173 IndexSetIterator elements(one);
174 while ((element = elements.next()) != 0) {
175 LRG &lrg = ifg->lrgs(element);
176 if (mask.overlap(lrg.mask())) {
177 insert(element);
178 if( !lrg.mask().is_AllStack() ) {
179 reg_degree += lrg1.compute_degree(lrg);
180 if( reg_degree >= fail_degree ) return reg_degree;
181 } else {
182 // !!!!! Danger! No update to reg_degree despite having a neighbor.
183 // A variant of the Briggs assertion.
184 // Not needed if I simplify during coalesce, ala George/Appel.
185 assert( lrg.lo_degree(), "" );
186 }
187 }
188 }
189 // Add neighbors of two as well
190 IndexSetIterator elements2(two);
191 while ((element = elements2.next()) != 0) {
192 LRG &lrg = ifg->lrgs(element);
193 if (mask.overlap(lrg.mask())) {
194 if (insert(element)) {
195 if( !lrg.mask().is_AllStack() ) {
196 reg_degree += lrg2.compute_degree(lrg);
197 if( reg_degree >= fail_degree ) return reg_degree;
198 } else {
199 // !!!!! Danger! No update to reg_degree despite having a neighbor.
200 // A variant of the Briggs assertion.
201 // Not needed if I simplify during coalesce, ala George/Appel.
202 assert( lrg.lo_degree(), "" );
203 }
204 }
205 }
206 }
207
208 return reg_degree;
209}
210
211//---------------------------- IndexSet() -----------------------------
212// A deep copy constructor. This is used when you need a scratch copy of this set.
213
214IndexSet::IndexSet (IndexSet *set) {
215#ifdef ASSERT
216 _serial_number = _serial_count++;
217 set->check_watch("copied", _serial_number);
218 check_watch("initialized by copy", set->_serial_number);
219 _max_elements = set->_max_elements;
220#endif
221 _count = set->_count;
222 _max_blocks = set->_max_blocks;
223 if (_max_blocks <= preallocated_block_list_size) {
224 _blocks = _preallocated_block_list;
225 } else {
226 _blocks =
227 (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks);
228 }
229 for (uint i = 0; i < _max_blocks; i++) {
230 BitBlock *block = set->_blocks[i];
231 if (block == &_empty_block) {
232 set_block(i, &_empty_block);
233 } else {
234 BitBlock *new_block = alloc_block();
235 memcpy(new_block->words(), block->words(), sizeof(uint32_t) * words_per_block);
236 set_block(i, new_block);
237 }
238 }
239}
240
241//---------------------------- IndexSet::initialize() -----------------------------
242// Prepare an IndexSet for use.
243
244void IndexSet::initialize(uint max_elements) {
245#ifdef ASSERT
246 _serial_number = _serial_count++;
247 check_watch("initialized", max_elements);
248 _max_elements = max_elements;
249#endif
250 _count = 0;
251 _max_blocks = (max_elements + bits_per_block - 1) / bits_per_block;
252
253 if (_max_blocks <= preallocated_block_list_size) {
254 _blocks = _preallocated_block_list;
255 } else {
256 _blocks = (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock*) * _max_blocks);
257 }
258 for (uint i = 0; i < _max_blocks; i++) {
259 set_block(i, &_empty_block);
260 }
261}
262
263//---------------------------- IndexSet::initialize()------------------------------
264// Prepare an IndexSet for use. If it needs to allocate its _blocks array, it does
265// so from the Arena passed as a parameter. BitBlock allocation is still done from
266// the static Arena which was set with reset_memory().
267
268void IndexSet::initialize(uint max_elements, Arena *arena) {
269#ifdef ASSERT
270 _serial_number = _serial_count++;
271 check_watch("initialized2", max_elements);
272 _max_elements = max_elements;
273#endif // ASSERT
274 _count = 0;
275 _max_blocks = (max_elements + bits_per_block - 1) / bits_per_block;
276
277 if (_max_blocks <= preallocated_block_list_size) {
278 _blocks = _preallocated_block_list;
279 } else {
280 _blocks = (IndexSet::BitBlock**) arena->Amalloc_4(sizeof(IndexSet::BitBlock*) * _max_blocks);
281 }
282 for (uint i = 0; i < _max_blocks; i++) {
283 set_block(i, &_empty_block);
284 }
285}
286
287//---------------------------- IndexSet::swap() -----------------------------
288// Exchange two IndexSets.
289
290void IndexSet::swap(IndexSet *set) {
291#ifdef ASSERT
292 assert(_max_elements == set->_max_elements, "must have same universe size to swap");
293 check_watch("swap", set->_serial_number);
294 set->check_watch("swap", _serial_number);
295#endif
296
297 for (uint i = 0; i < _max_blocks; i++) {
298 BitBlock *temp = _blocks[i];
299 set_block(i, set->_blocks[i]);
300 set->set_block(i, temp);
301 }
302 uint temp = _count;
303 _count = set->_count;
304 set->_count = temp;
305}
306
307//---------------------------- IndexSet::dump() -----------------------------
308// Print this set. Used for debugging.
309
310#ifndef PRODUCT
311void IndexSet::dump() const {
312 IndexSetIterator elements(this);
313
314 tty->print("{");
315 uint i;
316 while ((i = elements.next()) != 0) {
317 tty->print("L%d ", i);
318 }
319 tty->print_cr("}");
320}
321#endif
322
323#ifdef ASSERT
324//---------------------------- IndexSet::tally_iteration_statistics() -----------------------------
325// Update block/bit counts to reflect that this set has been iterated over.
326
327void IndexSet::tally_iteration_statistics() const {
328 inc_stat_counter(&_total_bits, count());
329
330 for (uint i = 0; i < _max_blocks; i++) {
331 if (_blocks[i] != &_empty_block) {
332 inc_stat_counter(&_total_used_blocks, 1);
333 } else {
334 inc_stat_counter(&_total_unused_blocks, 1);
335 }
336 }
337}
338
339//---------------------------- IndexSet::print_statistics() -----------------------------
340// Print statistics about IndexSet usage.
341
342void IndexSet::print_statistics() {
343 julong total_blocks = _total_used_blocks + _total_unused_blocks;
344 tty->print_cr ("Accumulated IndexSet usage statistics:");
345 tty->print_cr ("--------------------------------------");
346 tty->print_cr (" Iteration:");
347 tty->print_cr (" blocks visited: " UINT64_FORMAT, total_blocks);
348 tty->print_cr (" blocks empty: %4.2f%%", 100.0*(double)_total_unused_blocks/total_blocks);
349 tty->print_cr (" bit density (bits/used blocks): %4.2f", (double)_total_bits/_total_used_blocks);
350 tty->print_cr (" bit density (bits/all blocks): %4.2f", (double)_total_bits/total_blocks);
351 tty->print_cr (" Allocation:");
352 tty->print_cr (" blocks allocated: " UINT64_FORMAT, _alloc_new);
353 tty->print_cr (" blocks used/reused: " UINT64_FORMAT, _alloc_total);
354}
355
356//---------------------------- IndexSet::verify() -----------------------------
357// Expensive test of IndexSet sanity. Ensure that the count agrees with the
358// number of bits in the blocks. Make sure the iterator is seeing all elements
359// of the set. Meant for use during development.
360
361void IndexSet::verify() const {
362 assert(!member(0), "zero cannot be a member");
363 uint count = 0;
364 uint i;
365 for (i = 1; i < _max_elements; i++) {
366 if (member(i)) {
367 count++;
368 assert(count <= _count, "_count is messed up");
369 }
370 }
371
372 IndexSetIterator elements(this);
373 count = 0;
374 while ((i = elements.next()) != 0) {
375 count++;
376 assert(member(i), "returned a non member");
377 assert(count <= _count, "iterator returned wrong number of elements");
378 }
379}
380#endif
381
382//---------------------------- IndexSetIterator() -----------------------------
383// Create an iterator for a set. If empty blocks are detected when iterating
384// over the set, these blocks are replaced.
385
386IndexSetIterator::IndexSetIterator(IndexSet *set) {
387#ifdef ASSERT
388 if (CollectIndexSetStatistics) {
389 set->tally_iteration_statistics();
390 }
391 set->check_watch("traversed", set->count());
392#endif
393 if (set->is_empty()) {
394 _current = 0;
395 _next_word = IndexSet::words_per_block;
396 _next_block = 1;
397 _max_blocks = 1;
398
399 // We don't need the following values when we iterate over an empty set.
400 // The commented out code is left here to document that the omission
401 // is intentional.
402 //
403 //_value = 0;
404 //_words = NULL;
405 //_blocks = NULL;
406 //_set = NULL;
407 } else {
408 _current = 0;
409 _value = 0;
410 _next_block = 0;
411 _next_word = IndexSet::words_per_block;
412
413 _max_blocks = set->_max_blocks;
414 _words = NULL;
415 _blocks = set->_blocks;
416 _set = set;
417 }
418}
419
420//---------------------------- IndexSetIterator(const) -----------------------------
421// Iterate over a constant IndexSet.
422
423IndexSetIterator::IndexSetIterator(const IndexSet *set) {
424#ifdef ASSERT
425 if (CollectIndexSetStatistics) {
426 set->tally_iteration_statistics();
427 }
428 // We don't call check_watch from here to avoid bad recursion.
429 // set->check_watch("traversed const", set->count());
430#endif
431 if (set->is_empty()) {
432 _current = 0;
433 _next_word = IndexSet::words_per_block;
434 _next_block = 1;
435 _max_blocks = 1;
436
437 // We don't need the following values when we iterate over an empty set.
438 // The commented out code is left here to document that the omission
439 // is intentional.
440 //
441 //_value = 0;
442 //_words = NULL;
443 //_blocks = NULL;
444 //_set = NULL;
445 } else {
446 _current = 0;
447 _value = 0;
448 _next_block = 0;
449 _next_word = IndexSet::words_per_block;
450
451 _max_blocks = set->_max_blocks;
452 _words = NULL;
453 _blocks = set->_blocks;
454 _set = NULL;
455 }
456}
457
458//---------------------------- List16Iterator::advance_and_next() -----------------------------
459// Advance to the next non-empty word in the set being iterated over. Return the next element
460// if there is one. If we are done, return 0. This method is called from the next() method
461// when it gets done with a word.
462
463uint IndexSetIterator::advance_and_next() {
464 // See if there is another non-empty word in the current block.
465 for (uint wi = _next_word; wi < (unsigned)IndexSet::words_per_block; wi++) {
466 if (_words[wi] != 0) {
467 // Found a non-empty word.
468 _value = ((_next_block - 1) * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word);
469 _current = _words[wi];
470
471 _next_word = wi+1;
472
473 return next();
474 }
475 }
476
477 // We ran out of words in the current block. Advance to next non-empty block.
478 for (uint bi = _next_block; bi < _max_blocks; bi++) {
479 if (_blocks[bi] != &IndexSet::_empty_block) {
480 // Found a non-empty block.
481
482 _words = _blocks[bi]->words();
483 for (uint wi = 0; wi < (unsigned)IndexSet::words_per_block; wi++) {
484 if (_words[wi] != 0) {
485 // Found a non-empty word.
486 _value = (bi * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word);
487 _current = _words[wi];
488
489 _next_block = bi+1;
490 _next_word = wi+1;
491
492 return next();
493 }
494 }
495
496 // All of the words in the block were empty. Replace
497 // the block with the empty block.
498 if (_set) {
499 _set->free_block(bi);
500 }
501 }
502 }
503
504 // These assignments make redundant calls to next on a finished iterator
505 // faster. Probably not necessary.
506 _next_block = _max_blocks;
507 _next_word = IndexSet::words_per_block;
508
509 // No more words.
510 return 0;
511}
512