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.
22 *
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
38 IndexSet::BitBlock IndexSet::_empty_block = IndexSet::BitBlock();
39
40 #ifdef ASSERT
41 // Initialize statistics counters
42 julong IndexSet::_alloc_new = 0;
43 julong IndexSet::_alloc_total = 0;
44
45 julong IndexSet::_total_bits = 0;
46 julong IndexSet::_total_used_blocks = 0;
47 julong IndexSet::_total_unused_blocks = 0;
48
49 // Per set, or all sets operation tracing
50 int 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
populate_free_list()57 void 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
alloc_block()88 IndexSet::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
alloc_block_containing(uint element)111 IndexSet::BitBlock *IndexSet::alloc_block_containing(uint element) {
112 BitBlock *block = alloc_block();
113 uint bi = get_block_index(element);
114 if (bi >= _current_block_limit) {
115 _current_block_limit = bi + 1;
116 }
117 _blocks[bi] = block;
118 return block;
119 }
120
121 //---------------------------- IndexSet::free_block() -------------------------
122 // Add a BitBlock to the free list.
123
free_block(uint i)124 void IndexSet::free_block(uint i) {
125 debug_only(check_watch("free block", i));
126 assert(i < _max_blocks, "block index too large");
127 BitBlock *block = _blocks[i];
128 assert(block != &_empty_block, "cannot free the empty block");
129 block->set_next((IndexSet::BitBlock*)Compile::current()->indexSet_free_block_list());
130 Compile::current()->set_indexSet_free_block_list(block);
131 set_block(i, &_empty_block);
132 }
133
134 //------------------------------lrg_union--------------------------------------
135 // Compute the union of all elements of one and two which interfere with
136 // the RegMask mask. If the degree of the union becomes exceeds
137 // fail_degree, the union bails out. The underlying set is cleared before
138 // the union is performed.
139
lrg_union(uint lr1,uint lr2,const uint fail_degree,const PhaseIFG * ifg,const RegMask & mask)140 uint IndexSet::lrg_union(uint lr1, uint lr2,
141 const uint fail_degree,
142 const PhaseIFG *ifg,
143 const RegMask &mask ) {
144 IndexSet *one = ifg->neighbors(lr1);
145 IndexSet *two = ifg->neighbors(lr2);
146 LRG &lrg1 = ifg->lrgs(lr1);
147 LRG &lrg2 = ifg->lrgs(lr2);
148 #ifdef ASSERT
149 assert(_max_elements == one->_max_elements, "max element mismatch");
150 check_watch("union destination");
151 one->check_watch("union source");
152 two->check_watch("union source");
153 #endif
154
155 // Compute the degree of the combined live-range. The combined
156 // live-range has the union of the original live-ranges' neighbors set as
157 // well as the neighbors of all intermediate copies, minus those neighbors
158 // that can not use the intersected allowed-register-set.
159
160 // Copy the larger set. Insert the smaller set into the larger.
161 if (two->count() > one->count()) {
162 IndexSet *temp = one;
163 one = two;
164 two = temp;
165 }
166
167 clear();
168
169 // Used to compute degree of register-only interferences. Infinite-stack
170 // neighbors do not alter colorability, as they can always color to some
171 // other color. (A variant of the Briggs assertion)
172 uint reg_degree = 0;
173
174 uint element = 0;
175 // Load up the combined interference set with the neighbors of one
176 if (!one->is_empty()) {
177 IndexSetIterator elements(one);
178 while ((element = elements.next()) != 0) {
179 LRG &lrg = ifg->lrgs(element);
180 if (mask.overlap(lrg.mask())) {
181 insert(element);
182 if (!lrg.mask().is_AllStack()) {
183 reg_degree += lrg1.compute_degree(lrg);
184 if (reg_degree >= fail_degree) return reg_degree;
185 } else {
186 // !!!!! Danger! No update to reg_degree despite having a neighbor.
187 // A variant of the Briggs assertion.
188 // Not needed if I simplify during coalesce, ala George/Appel.
189 assert(lrg.lo_degree(), "");
190 }
191 }
192 }
193 }
194 // Add neighbors of two as well
195
196 if (!two->is_empty()) {
197 IndexSetIterator elements2(two);
198 while ((element = elements2.next()) != 0) {
199 LRG &lrg = ifg->lrgs(element);
200 if (mask.overlap(lrg.mask())) {
201 if (insert(element)) {
202 if (!lrg.mask().is_AllStack()) {
203 reg_degree += lrg2.compute_degree(lrg);
204 if (reg_degree >= fail_degree) return reg_degree;
205 } else {
206 // !!!!! Danger! No update to reg_degree despite having a neighbor.
207 // A variant of the Briggs assertion.
208 // Not needed if I simplify during coalesce, ala George/Appel.
209 assert(lrg.lo_degree(), "");
210 }
211 }
212 }
213 }
214 }
215
216 return reg_degree;
217 }
218
219 //---------------------------- IndexSet() -----------------------------
220 // A deep copy constructor. This is used when you need a scratch copy of this set.
221
IndexSet(IndexSet * set)222 IndexSet::IndexSet (IndexSet *set) {
223 #ifdef ASSERT
224 _serial_number = _serial_count++;
225 set->check_watch("copied", _serial_number);
226 check_watch("initialized by copy", set->_serial_number);
227 _max_elements = set->_max_elements;
228 #endif
229 _count = set->_count;
230 _current_block_limit = set->_current_block_limit;
231 _max_blocks = set->_max_blocks;
232 if (_max_blocks <= preallocated_block_list_size) {
233 _blocks = _preallocated_block_list;
234 } else {
235 _blocks =
236 (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks);
237 }
238 for (uint i = 0; i < _max_blocks; i++) {
239 BitBlock *block = set->_blocks[i];
240 if (block == &_empty_block) {
241 set_block(i, &_empty_block);
242 } else {
243 BitBlock *new_block = alloc_block();
244 memcpy(new_block->words(), block->words(), sizeof(uint32_t) * words_per_block);
245 set_block(i, new_block);
246 }
247 }
248 }
249
250 //---------------------------- IndexSet::initialize() -----------------------------
251 // Prepare an IndexSet for use.
252
initialize(uint max_elements)253 void IndexSet::initialize(uint max_elements) {
254 #ifdef ASSERT
255 _serial_number = _serial_count++;
256 check_watch("initialized", max_elements);
257 _max_elements = max_elements;
258 #endif
259 _count = 0;
260 _current_block_limit = 0;
261 _max_blocks = (max_elements + bits_per_block - 1) / bits_per_block;
262
263 if (_max_blocks <= preallocated_block_list_size) {
264 _blocks = _preallocated_block_list;
265 } else {
266 _blocks = (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock*) * _max_blocks);
267 }
268 for (uint i = 0; i < _max_blocks; i++) {
269 set_block(i, &_empty_block);
270 }
271 }
272
273 //---------------------------- IndexSet::initialize()------------------------------
274 // Prepare an IndexSet for use. If it needs to allocate its _blocks array, it does
275 // so from the Arena passed as a parameter. BitBlock allocation is still done from
276 // the static Arena which was set with reset_memory().
277
initialize(uint max_elements,Arena * arena)278 void IndexSet::initialize(uint max_elements, Arena *arena) {
279 #ifdef ASSERT
280 _serial_number = _serial_count++;
281 check_watch("initialized2", max_elements);
282 _max_elements = max_elements;
283 #endif // ASSERT
284 _count = 0;
285 _current_block_limit = 0;
286 _max_blocks = (max_elements + bits_per_block - 1) / bits_per_block;
287
288 if (_max_blocks <= preallocated_block_list_size) {
289 _blocks = _preallocated_block_list;
290 } else {
291 _blocks = (IndexSet::BitBlock**) arena->Amalloc_4(sizeof(IndexSet::BitBlock*) * _max_blocks);
292 }
293 for (uint i = 0; i < _max_blocks; i++) {
294 set_block(i, &_empty_block);
295 }
296 }
297
298 //---------------------------- IndexSet::swap() -----------------------------
299 // Exchange two IndexSets.
300
swap(IndexSet * set)301 void IndexSet::swap(IndexSet *set) {
302 #ifdef ASSERT
303 assert(_max_elements == set->_max_elements, "must have same universe size to swap");
304 check_watch("swap", set->_serial_number);
305 set->check_watch("swap", _serial_number);
306 #endif
307
308 uint max = MAX2(_current_block_limit, set->_current_block_limit);
309 for (uint i = 0; i < max; i++) {
310 BitBlock *temp = _blocks[i];
311 set_block(i, set->_blocks[i]);
312 set->set_block(i, temp);
313 }
314 uint temp = _count;
315 _count = set->_count;
316 set->_count = temp;
317
318 temp = _current_block_limit;
319 _current_block_limit = set->_current_block_limit;
320 set->_current_block_limit = temp;
321
322 }
323
324 //---------------------------- IndexSet::dump() -----------------------------
325 // Print this set. Used for debugging.
326
327 #ifndef PRODUCT
dump() const328 void IndexSet::dump() const {
329 IndexSetIterator elements(this);
330
331 tty->print("{");
332 uint i;
333 while ((i = elements.next()) != 0) {
334 tty->print("L%d ", i);
335 }
336 tty->print_cr("}");
337 }
338 #endif
339
340 #ifdef ASSERT
341 //---------------------------- IndexSet::tally_iteration_statistics() -----------------------------
342 // Update block/bit counts to reflect that this set has been iterated over.
343
tally_iteration_statistics() const344 void IndexSet::tally_iteration_statistics() const {
345 inc_stat_counter(&_total_bits, count());
346
347 for (uint i = 0; i < _max_blocks; i++) {
348 if (_blocks[i] != &_empty_block) {
349 inc_stat_counter(&_total_used_blocks, 1);
350 } else {
351 inc_stat_counter(&_total_unused_blocks, 1);
352 }
353 }
354 }
355
356 //---------------------------- IndexSet::print_statistics() -----------------------------
357 // Print statistics about IndexSet usage.
358
print_statistics()359 void IndexSet::print_statistics() {
360 julong total_blocks = _total_used_blocks + _total_unused_blocks;
361 tty->print_cr ("Accumulated IndexSet usage statistics:");
362 tty->print_cr ("--------------------------------------");
363 tty->print_cr (" Iteration:");
364 tty->print_cr (" blocks visited: " UINT64_FORMAT, total_blocks);
365 tty->print_cr (" blocks empty: %4.2f%%", 100.0*(double)_total_unused_blocks/total_blocks);
366 tty->print_cr (" bit density (bits/used blocks): %4.2f", (double)_total_bits/_total_used_blocks);
367 tty->print_cr (" bit density (bits/all blocks): %4.2f", (double)_total_bits/total_blocks);
368 tty->print_cr (" Allocation:");
369 tty->print_cr (" blocks allocated: " UINT64_FORMAT, _alloc_new);
370 tty->print_cr (" blocks used/reused: " UINT64_FORMAT, _alloc_total);
371 }
372
373 //---------------------------- IndexSet::verify() -----------------------------
374 // Expensive test of IndexSet sanity. Ensure that the count agrees with the
375 // number of bits in the blocks. Make sure the iterator is seeing all elements
376 // of the set. Meant for use during development.
377
verify() const378 void IndexSet::verify() const {
379 assert(!member(0), "zero cannot be a member");
380 uint count = 0;
381 uint i;
382 for (i = 1; i < _max_elements; i++) {
383 if (member(i)) {
384 count++;
385 assert(count <= _count, "_count is messed up");
386 }
387 }
388
389 IndexSetIterator elements(this);
390 count = 0;
391 while ((i = elements.next()) != 0) {
392 count++;
393 assert(member(i), "returned a non member");
394 assert(count <= _count, "iterator returned wrong number of elements");
395 }
396 }
397 #endif
398
399 //---------------------------- IndexSetIterator() -----------------------------
400 // Create an iterator for a set. If empty blocks are detected when iterating
401 // over the set, these blocks are replaced.
402
403 //---------------------------- List16Iterator::advance_and_next() -----------------------------
404 // Advance to the next non-empty word in the set being iterated over. Return the next element
405 // if there is one. If we are done, return 0. This method is called from the next() method
406 // when it gets done with a word.
407
advance_and_next()408 uint IndexSetIterator::advance_and_next() {
409 // See if there is another non-empty word in the current block.
410 for (uint wi = _next_word; wi < (unsigned)IndexSet::words_per_block; wi++) {
411 if (_words[wi] != 0) {
412 // Found a non-empty word.
413 _value = ((_next_block - 1) * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word);
414 _current = _words[wi];
415 _next_word = wi + 1;
416 return next_value();
417 }
418 }
419
420 // We ran out of words in the current block. Advance to next non-empty block.
421 for (uint bi = _next_block; bi < _max_blocks; bi++) {
422 if (_blocks[bi] != &IndexSet::_empty_block) {
423 // Found a non-empty block.
424
425 _words = _blocks[bi]->words();
426 for (uint wi = 0; wi < (unsigned)IndexSet::words_per_block; wi++) {
427 if (_words[wi] != 0) {
428 // Found a non-empty word.
429 _value = (bi * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word);
430 _current = _words[wi];
431
432 _next_block = bi+1;
433 _next_word = wi+1;
434 return next_value();
435 }
436 }
437
438 // All of the words in the block were empty. Replace
439 // the block with the empty block.
440 if (_set) {
441 _set->free_block(bi);
442 }
443 }
444 }
445
446 // No more words.
447 return 0;
448 }
449