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comparison src/share/vm/compiler/methodLiveness.cpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 1998-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // The MethodLiveness class performs a simple liveness analysis on a method
26 // in order to decide which locals are live (that is, will be used again) at
27 // a particular bytecode index (bci).
28 //
29 // The algorithm goes:
30 //
31 // 1. Break the method into a set of basic blocks. For each basic block we
32 // also keep track of its set of predecessors through normal control flow
33 // and predecessors through exceptional control flow.
34 //
35 // 2. For each basic block, compute two sets, gen (the set of values used before
36 // they are defined) and kill (the set of values defined before they are used)
37 // in the basic block. A basic block "needs" the locals in its gen set to
38 // perform its computation. A basic block "provides" values for the locals in
39 // its kill set, allowing a need from a successor to be ignored.
40 //
41 // 3. Liveness information (the set of locals which are needed) is pushed backwards through
42 // the program, from blocks to their predecessors. We compute and store liveness
43 // information for the normal/exceptional exit paths for each basic block. When
44 // this process reaches a fixed point, we are done.
45 //
46 // 4. When we are asked about the liveness at a particular bci with a basic block, we
47 // compute gen/kill sets which represent execution from that bci to the exit of
48 // its blocks. We then compose this range gen/kill information with the normal
49 // and exceptional exit information for the block to produce liveness information
50 // at that bci.
51 //
52 // The algorithm is approximate in many respects. Notably:
53 //
54 // 1. We do not do the analysis necessary to match jsr's with the appropriate ret.
55 // Instead we make the conservative assumption that any ret can return to any
56 // jsr return site.
57 // 2. Instead of computing the effects of exceptions at every instruction, we
58 // summarize the effects of all exceptional continuations from the block as
59 // a single set (_exception_exit), losing some information but simplifying the
60 // analysis.
61
62
63 # include "incls/_precompiled.incl"
64 # include "incls/_methodLiveness.cpp.incl"
65
66 //--------------------------------------------------------------------------
67 // The BitCounter class is used for counting the number of bits set in
68 // some BitMap. It is only used when collecting liveness statistics.
69
70 #ifndef PRODUCT
71
72 class BitCounter: public BitMapClosure {
73 private:
74 int _count;
75 public:
76 BitCounter() : _count(0) {}
77
78 // Callback when bit in map is set
79 virtual void do_bit(size_t offset) {
80 _count++;
81 }
82
83 int count() {
84 return _count;
85 }
86 };
87
88
89 //--------------------------------------------------------------------------
90
91
92 // Counts
93 long MethodLiveness::_total_bytes = 0;
94 int MethodLiveness::_total_methods = 0;
95
96 long MethodLiveness::_total_blocks = 0;
97 int MethodLiveness::_max_method_blocks = 0;
98
99 long MethodLiveness::_total_edges = 0;
100 int MethodLiveness::_max_block_edges = 0;
101
102 long MethodLiveness::_total_exc_edges = 0;
103 int MethodLiveness::_max_block_exc_edges = 0;
104
105 long MethodLiveness::_total_method_locals = 0;
106 int MethodLiveness::_max_method_locals = 0;
107
108 long MethodLiveness::_total_locals_queried = 0;
109 long MethodLiveness::_total_live_locals_queried = 0;
110
111 long MethodLiveness::_total_visits = 0;
112
113 #endif
114
115 // Timers
116 elapsedTimer MethodLiveness::_time_build_graph;
117 elapsedTimer MethodLiveness::_time_gen_kill;
118 elapsedTimer MethodLiveness::_time_flow;
119 elapsedTimer MethodLiveness::_time_query;
120 elapsedTimer MethodLiveness::_time_total;
121
122 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method)
123 #ifdef COMPILER1
124 : _bci_block_start((uintptr_t*)arena->Amalloc((method->code_size() >> LogBitsPerByte) + 1), method->code_size())
125 #endif
126 {
127 _arena = arena;
128 _method = method;
129 _bit_map_size_bits = method->max_locals();
130 _bit_map_size_words = (_bit_map_size_bits / sizeof(unsigned int)) + 1;
131
132 #ifdef COMPILER1
133 _bci_block_start.clear();
134 #endif
135 }
136
137 void MethodLiveness::compute_liveness() {
138 #ifndef PRODUCT
139 if (TraceLivenessGen) {
140 tty->print_cr("################################################################");
141 tty->print("# Computing liveness information for ");
142 method()->print_short_name();
143 }
144
145 if (TimeLivenessAnalysis) _time_total.start();
146 #endif
147
148 {
149 TraceTime buildGraph(NULL, &_time_build_graph, TimeLivenessAnalysis);
150 init_basic_blocks();
151 }
152 {
153 TraceTime genKill(NULL, &_time_gen_kill, TimeLivenessAnalysis);
154 init_gen_kill();
155 }
156 {
157 TraceTime flow(NULL, &_time_flow, TimeLivenessAnalysis);
158 propagate_liveness();
159 }
160
161 #ifndef PRODUCT
162 if (TimeLivenessAnalysis) _time_total.stop();
163
164 if (TimeLivenessAnalysis) {
165 // Collect statistics
166 _total_bytes += method()->code_size();
167 _total_methods++;
168
169 int num_blocks = _block_count;
170 _total_blocks += num_blocks;
171 _max_method_blocks = MAX2(num_blocks,_max_method_blocks);
172
173 for (int i=0; i<num_blocks; i++) {
174 BasicBlock *block = _block_list[i];
175
176 int numEdges = block->_normal_predecessors->length();
177 int numExcEdges = block->_exception_predecessors->length();
178
179 _total_edges += numEdges;
180 _total_exc_edges += numExcEdges;
181 _max_block_edges = MAX2(numEdges,_max_block_edges);
182 _max_block_exc_edges = MAX2(numExcEdges,_max_block_exc_edges);
183 }
184
185 int numLocals = _bit_map_size_bits;
186 _total_method_locals += numLocals;
187 _max_method_locals = MAX2(numLocals,_max_method_locals);
188 }
189 #endif
190 }
191
192
193 void MethodLiveness::init_basic_blocks() {
194 bool bailout = false;
195
196 int method_len = method()->code_size();
197 ciMethodBlocks *mblocks = method()->get_method_blocks();
198
199 // Create an array to store the bci->BasicBlock mapping.
200 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL);
201
202 _block_count = mblocks->num_blocks();
203 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count);
204
205 // Used for patching up jsr/ret control flow.
206 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5);
207 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5);
208
209 // generate our block list from ciMethodBlocks
210 for (int blk = 0; blk < _block_count; blk++) {
211 ciBlock *cib = mblocks->block(blk);
212 int start_bci = cib->start_bci();
213 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci());
214 _block_map->at_put(start_bci, _block_list[blk]);
215 #ifdef COMPILER1
216 // mark all bcis where a new basic block starts
217 _bci_block_start.set_bit(start_bci);
218 #endif // COMPILER1
219 }
220 // fill in the predecessors of blocks
221 ciBytecodeStream bytes(method());
222
223 for (int blk = 0; blk < _block_count; blk++) {
224 BasicBlock *current_block = _block_list[blk];
225 int bci = mblocks->block(blk)->control_bci();
226
227 if (bci == ciBlock::fall_through_bci) {
228 int limit = current_block->limit_bci();
229 if (limit < method_len) {
230 BasicBlock *next = _block_map->at(limit);
231 assert( next != NULL, "must be a block immediately following this one.");
232 next->add_normal_predecessor(current_block);
233 }
234 continue;
235 }
236 bytes.reset_to_bci(bci);
237 Bytecodes::Code code = bytes.next();
238 BasicBlock *dest;
239
240 // Now we need to interpret the instruction's effect
241 // on control flow.
242 assert (current_block != NULL, "we must have a current block");
243 switch (code) {
244 case Bytecodes::_ifeq:
245 case Bytecodes::_ifne:
246 case Bytecodes::_iflt:
247 case Bytecodes::_ifge:
248 case Bytecodes::_ifgt:
249 case Bytecodes::_ifle:
250 case Bytecodes::_if_icmpeq:
251 case Bytecodes::_if_icmpne:
252 case Bytecodes::_if_icmplt:
253 case Bytecodes::_if_icmpge:
254 case Bytecodes::_if_icmpgt:
255 case Bytecodes::_if_icmple:
256 case Bytecodes::_if_acmpeq:
257 case Bytecodes::_if_acmpne:
258 case Bytecodes::_ifnull:
259 case Bytecodes::_ifnonnull:
260 // Two way branch. Set predecessors at each destination.
261 dest = _block_map->at(bytes.next_bci());
262 assert(dest != NULL, "must be a block immediately following this one.");
263 dest->add_normal_predecessor(current_block);
264
265 dest = _block_map->at(bytes.get_dest());
266 assert(dest != NULL, "branch desination must start a block.");
267 dest->add_normal_predecessor(current_block);
268 break;
269 case Bytecodes::_goto:
270 dest = _block_map->at(bytes.get_dest());
271 assert(dest != NULL, "branch desination must start a block.");
272 dest->add_normal_predecessor(current_block);
273 break;
274 case Bytecodes::_goto_w:
275 dest = _block_map->at(bytes.get_far_dest());
276 assert(dest != NULL, "branch desination must start a block.");
277 dest->add_normal_predecessor(current_block);
278 break;
279 case Bytecodes::_tableswitch:
280 {
281 Bytecode_tableswitch *tableswitch =
282 Bytecode_tableswitch_at(bytes.cur_bcp());
283
284 int len = tableswitch->length();
285
286 dest = _block_map->at(bci + tableswitch->default_offset());
287 assert(dest != NULL, "branch desination must start a block.");
288 dest->add_normal_predecessor(current_block);
289 while (--len >= 0) {
290 dest = _block_map->at(bci + tableswitch->dest_offset_at(len));
291 assert(dest != NULL, "branch desination must start a block.");
292 dest->add_normal_predecessor(current_block);
293 }
294 break;
295 }
296
297 case Bytecodes::_lookupswitch:
298 {
299 Bytecode_lookupswitch *lookupswitch =
300 Bytecode_lookupswitch_at(bytes.cur_bcp());
301
302 int npairs = lookupswitch->number_of_pairs();
303
304 dest = _block_map->at(bci + lookupswitch->default_offset());
305 assert(dest != NULL, "branch desination must start a block.");
306 dest->add_normal_predecessor(current_block);
307 while(--npairs >= 0) {
308 LookupswitchPair *pair = lookupswitch->pair_at(npairs);
309 dest = _block_map->at( bci + pair->offset());
310 assert(dest != NULL, "branch desination must start a block.");
311 dest->add_normal_predecessor(current_block);
312 }
313 break;
314 }
315
316 case Bytecodes::_jsr:
317 {
318 assert(bytes.is_wide()==false, "sanity check");
319 dest = _block_map->at(bytes.get_dest());
320 assert(dest != NULL, "branch desination must start a block.");
321 dest->add_normal_predecessor(current_block);
322 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
323 assert(jsrExit != NULL, "jsr return bci must start a block.");
324 jsr_exit_list->append(jsrExit);
325 break;
326 }
327 case Bytecodes::_jsr_w:
328 {
329 dest = _block_map->at(bytes.get_far_dest());
330 assert(dest != NULL, "branch desination must start a block.");
331 dest->add_normal_predecessor(current_block);
332 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
333 assert(jsrExit != NULL, "jsr return bci must start a block.");
334 jsr_exit_list->append(jsrExit);
335 break;
336 }
337
338 case Bytecodes::_wide:
339 assert(false, "wide opcodes should not be seen here");
340 break;
341 case Bytecodes::_athrow:
342 case Bytecodes::_ireturn:
343 case Bytecodes::_lreturn:
344 case Bytecodes::_freturn:
345 case Bytecodes::_dreturn:
346 case Bytecodes::_areturn:
347 case Bytecodes::_return:
348 // These opcodes are not the normal predecessors of any other opcodes.
349 break;
350 case Bytecodes::_ret:
351 // We will patch up jsr/rets in a subsequent pass.
352 ret_list->append(current_block);
353 break;
354 case Bytecodes::_breakpoint:
355 // Bail out of there are breakpoints in here.
356 bailout = true;
357 break;
358 default:
359 // Do nothing.
360 break;
361 }
362 }
363 // Patch up the jsr/ret's. We conservatively assume that any ret
364 // can return to any jsr site.
365 int ret_list_len = ret_list->length();
366 int jsr_exit_list_len = jsr_exit_list->length();
367 if (ret_list_len > 0 && jsr_exit_list_len > 0) {
368 for (int i = jsr_exit_list_len - 1; i >= 0; i--) {
369 BasicBlock *jsrExit = jsr_exit_list->at(i);
370 for (int i = ret_list_len - 1; i >= 0; i--) {
371 jsrExit->add_normal_predecessor(ret_list->at(i));
372 }
373 }
374 }
375
376 // Compute exception edges.
377 for (int b=_block_count-1; b >= 0; b--) {
378 BasicBlock *block = _block_list[b];
379 int block_start = block->start_bci();
380 int block_limit = block->limit_bci();
381 ciExceptionHandlerStream handlers(method());
382 for (; !handlers.is_done(); handlers.next()) {
383 ciExceptionHandler* handler = handlers.handler();
384 int start = handler->start();
385 int limit = handler->limit();
386 int handler_bci = handler->handler_bci();
387
388 int intersect_start = MAX2(block_start, start);
389 int intersect_limit = MIN2(block_limit, limit);
390 if (intersect_start < intersect_limit) {
391 // The catch range has a nonempty intersection with this
392 // basic block. That means this basic block can be an
393 // exceptional predecessor.
394 _block_map->at(handler_bci)->add_exception_predecessor(block);
395
396 if (handler->is_catch_all()) {
397 // This is a catch-all block.
398 if (intersect_start == block_start && intersect_limit == block_limit) {
399 // The basic block is entirely contained in this catch-all block.
400 // Skip the rest of the exception handlers -- they can never be
401 // reached in execution.
402 break;
403 }
404 }
405 }
406 }
407 }
408 }
409
410 void MethodLiveness::init_gen_kill() {
411 for (int i=_block_count-1; i >= 0; i--) {
412 _block_list[i]->compute_gen_kill(method());
413 }
414 }
415
416 void MethodLiveness::propagate_liveness() {
417 int num_blocks = _block_count;
418 BasicBlock *block;
419
420 // We start our work list off with all blocks in it.
421 // Alternately, we could start off the work list with the list of all
422 // blocks which could exit the method directly, along with one block
423 // from any infinite loop. If this matters, it can be changed. It
424 // may not be clear from looking at the code, but the order of the
425 // workList will be the opposite of the creation order of the basic
426 // blocks, which should be decent for quick convergence (with the
427 // possible exception of exception handlers, which are all created
428 // early).
429 _work_list = NULL;
430 for (int i = 0; i < num_blocks; i++) {
431 block = _block_list[i];
432 block->set_next(_work_list);
433 block->set_on_work_list(true);
434 _work_list = block;
435 }
436
437
438 while ((block = work_list_get()) != NULL) {
439 block->propagate(this);
440 NOT_PRODUCT(_total_visits++;)
441 }
442 }
443
444 void MethodLiveness::work_list_add(BasicBlock *block) {
445 if (!block->on_work_list()) {
446 block->set_next(_work_list);
447 block->set_on_work_list(true);
448 _work_list = block;
449 }
450 }
451
452 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() {
453 BasicBlock *block = _work_list;
454 if (block != NULL) {
455 block->set_on_work_list(false);
456 _work_list = block->next();
457 }
458 return block;
459 }
460
461
462 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) {
463 int bci = entry_bci;
464 bool is_entry = false;
465 if (entry_bci == InvocationEntryBci) {
466 is_entry = true;
467 bci = 0;
468 }
469
470 MethodLivenessResult answer(NULL,0);
471
472 if (_block_count > 0) {
473 if (TimeLivenessAnalysis) _time_total.start();
474 if (TimeLivenessAnalysis) _time_query.start();
475
476 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" );
477 BasicBlock *block = _block_map->at(bci);
478 // We may not be at the block start, so search backwards to find the block
479 // containing bci.
480 int t = bci;
481 while (block == NULL && t > 0) {
482 block = _block_map->at(--t);
483 }
484 assert( block != NULL, "invalid bytecode index; must be instruction index" );
485 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci.");
486
487 answer = block->get_liveness_at(method(), bci);
488
489 if (is_entry && method()->is_synchronized() && !method()->is_static()) {
490 // Synchronized methods use the receiver once on entry.
491 answer.at_put(0, true);
492 }
493
494 #ifndef PRODUCT
495 if (TraceLivenessQuery) {
496 tty->print("Liveness query of ");
497 method()->print_short_name();
498 tty->print(" @ %d : result is ", bci);
499 answer.print_on(tty);
500 }
501
502 if (TimeLivenessAnalysis) _time_query.stop();
503 if (TimeLivenessAnalysis) _time_total.stop();
504 #endif
505 }
506
507 #ifndef PRODUCT
508 if (TimeLivenessAnalysis) {
509 // Collect statistics.
510 _total_locals_queried += _bit_map_size_bits;
511 BitCounter counter;
512 answer.iterate(&counter);
513 _total_live_locals_queried += counter.count();
514 }
515 #endif
516
517 return answer;
518 }
519
520
521 #ifndef PRODUCT
522
523 void MethodLiveness::print_times() {
524 tty->print_cr ("Accumulated liveness analysis times/statistics:");
525 tty->print_cr ("-----------------------------------------------");
526 tty->print_cr (" Total : %3.3f sec.", _time_total.seconds());
527 tty->print_cr (" Build graph : %3.3f sec. (%2.2f%%)", _time_build_graph.seconds(),
528 _time_build_graph.seconds() * 100 / _time_total.seconds());
529 tty->print_cr (" Gen / Kill : %3.3f sec. (%2.2f%%)", _time_gen_kill.seconds(),
530 _time_gen_kill.seconds() * 100 / _time_total.seconds());
531 tty->print_cr (" Dataflow : %3.3f sec. (%2.2f%%)", _time_flow.seconds(),
532 _time_flow.seconds() * 100 / _time_total.seconds());
533 tty->print_cr (" Query : %3.3f sec. (%2.2f%%)", _time_query.seconds(),
534 _time_query.seconds() * 100 / _time_total.seconds());
535 tty->print_cr (" #bytes : %8d (%3.0f bytes per sec)",
536 _total_bytes,
537 _total_bytes / _time_total.seconds());
538 tty->print_cr (" #methods : %8d (%3.0f methods per sec)",
539 _total_methods,
540 _total_methods / _time_total.seconds());
541 tty->print_cr (" avg locals : %3.3f max locals : %3d",
542 (float)_total_method_locals / _total_methods,
543 _max_method_locals);
544 tty->print_cr (" avg blocks : %3.3f max blocks : %3d",
545 (float)_total_blocks / _total_methods,
546 _max_method_blocks);
547 tty->print_cr (" avg bytes : %3.3f",
548 (float)_total_bytes / _total_methods);
549 tty->print_cr (" #blocks : %8d",
550 _total_blocks);
551 tty->print_cr (" avg normal predecessors : %3.3f max normal predecessors : %3d",
552 (float)_total_edges / _total_blocks,
553 _max_block_edges);
554 tty->print_cr (" avg exception predecessors : %3.3f max exception predecessors : %3d",
555 (float)_total_exc_edges / _total_blocks,
556 _max_block_exc_edges);
557 tty->print_cr (" avg visits : %3.3f",
558 (float)_total_visits / _total_blocks);
559 tty->print_cr (" #locals queried : %8d #live : %8d %%live : %2.2f%%",
560 _total_locals_queried,
561 _total_live_locals_queried,
562 100.0 * _total_live_locals_queried / _total_locals_queried);
563 }
564
565 #endif
566
567
568 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) :
569 _gen((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
570 analyzer->bit_map_size_bits()),
571 _kill((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
572 analyzer->bit_map_size_bits()),
573 _entry((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
574 analyzer->bit_map_size_bits()),
575 _normal_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
576 analyzer->bit_map_size_bits()),
577 _exception_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
578 analyzer->bit_map_size_bits()),
579 _last_bci(-1) {
580 _analyzer = analyzer;
581 _start_bci = start;
582 _limit_bci = limit;
583 _normal_predecessors =
584 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
585 _exception_predecessors =
586 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
587 _normal_exit.clear();
588 _exception_exit.clear();
589 _entry.clear();
590
591 // this initialization is not strictly necessary.
592 // _gen and _kill are cleared at the beginning of compute_gen_kill_range()
593 _gen.clear();
594 _kill.clear();
595 }
596
597
598
599 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) {
600 int start = _start_bci;
601 int limit = _limit_bci;
602
603 if (TraceLivenessGen) {
604 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci);
605 }
606
607 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors;
608
609 assert (start < split_bci && split_bci < limit, "improper split");
610
611 // Make a new block to cover the first half of the range.
612 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci);
613
614 // Assign correct values to the second half (this)
615 _normal_predecessors = first_half->_normal_predecessors;
616 _start_bci = split_bci;
617 add_normal_predecessor(first_half);
618
619 // Assign correct predecessors to the new first half
620 first_half->_normal_predecessors = save_predecessors;
621
622 return first_half;
623 }
624
625 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) {
626 ciBytecodeStream bytes(method);
627 bytes.reset_to_bci(start_bci());
628 bytes.set_max_bci(limit_bci());
629 compute_gen_kill_range(&bytes);
630
631 }
632
633 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) {
634 _gen.clear();
635 _kill.clear();
636
637 while (bytes->next() != ciBytecodeStream::EOBC()) {
638 compute_gen_kill_single(bytes);
639 }
640 }
641
642 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) {
643 int localNum;
644
645 // We prohibit _gen and _kill from having locals in common. If we
646 // know that one is definitely going to be applied before the other,
647 // we could save some computation time by relaxing this prohibition.
648
649 switch (instruction->cur_bc()) {
650 case Bytecodes::_nop:
651 case Bytecodes::_goto:
652 case Bytecodes::_goto_w:
653 case Bytecodes::_aconst_null:
654 case Bytecodes::_new:
655 case Bytecodes::_iconst_m1:
656 case Bytecodes::_iconst_0:
657 case Bytecodes::_iconst_1:
658 case Bytecodes::_iconst_2:
659 case Bytecodes::_iconst_3:
660 case Bytecodes::_iconst_4:
661 case Bytecodes::_iconst_5:
662 case Bytecodes::_fconst_0:
663 case Bytecodes::_fconst_1:
664 case Bytecodes::_fconst_2:
665 case Bytecodes::_bipush:
666 case Bytecodes::_sipush:
667 case Bytecodes::_lconst_0:
668 case Bytecodes::_lconst_1:
669 case Bytecodes::_dconst_0:
670 case Bytecodes::_dconst_1:
671 case Bytecodes::_ldc2_w:
672 case Bytecodes::_ldc:
673 case Bytecodes::_ldc_w:
674 case Bytecodes::_iaload:
675 case Bytecodes::_faload:
676 case Bytecodes::_baload:
677 case Bytecodes::_caload:
678 case Bytecodes::_saload:
679 case Bytecodes::_laload:
680 case Bytecodes::_daload:
681 case Bytecodes::_aaload:
682 case Bytecodes::_iastore:
683 case Bytecodes::_fastore:
684 case Bytecodes::_bastore:
685 case Bytecodes::_castore:
686 case Bytecodes::_sastore:
687 case Bytecodes::_lastore:
688 case Bytecodes::_dastore:
689 case Bytecodes::_aastore:
690 case Bytecodes::_pop:
691 case Bytecodes::_pop2:
692 case Bytecodes::_dup:
693 case Bytecodes::_dup_x1:
694 case Bytecodes::_dup_x2:
695 case Bytecodes::_dup2:
696 case Bytecodes::_dup2_x1:
697 case Bytecodes::_dup2_x2:
698 case Bytecodes::_swap:
699 case Bytecodes::_iadd:
700 case Bytecodes::_fadd:
701 case Bytecodes::_isub:
702 case Bytecodes::_fsub:
703 case Bytecodes::_imul:
704 case Bytecodes::_fmul:
705 case Bytecodes::_idiv:
706 case Bytecodes::_fdiv:
707 case Bytecodes::_irem:
708 case Bytecodes::_frem:
709 case Bytecodes::_ishl:
710 case Bytecodes::_ishr:
711 case Bytecodes::_iushr:
712 case Bytecodes::_iand:
713 case Bytecodes::_ior:
714 case Bytecodes::_ixor:
715 case Bytecodes::_l2f:
716 case Bytecodes::_l2i:
717 case Bytecodes::_d2f:
718 case Bytecodes::_d2i:
719 case Bytecodes::_fcmpl:
720 case Bytecodes::_fcmpg:
721 case Bytecodes::_ladd:
722 case Bytecodes::_dadd:
723 case Bytecodes::_lsub:
724 case Bytecodes::_dsub:
725 case Bytecodes::_lmul:
726 case Bytecodes::_dmul:
727 case Bytecodes::_ldiv:
728 case Bytecodes::_ddiv:
729 case Bytecodes::_lrem:
730 case Bytecodes::_drem:
731 case Bytecodes::_land:
732 case Bytecodes::_lor:
733 case Bytecodes::_lxor:
734 case Bytecodes::_ineg:
735 case Bytecodes::_fneg:
736 case Bytecodes::_i2f:
737 case Bytecodes::_f2i:
738 case Bytecodes::_i2c:
739 case Bytecodes::_i2s:
740 case Bytecodes::_i2b:
741 case Bytecodes::_lneg:
742 case Bytecodes::_dneg:
743 case Bytecodes::_l2d:
744 case Bytecodes::_d2l:
745 case Bytecodes::_lshl:
746 case Bytecodes::_lshr:
747 case Bytecodes::_lushr:
748 case Bytecodes::_i2l:
749 case Bytecodes::_i2d:
750 case Bytecodes::_f2l:
751 case Bytecodes::_f2d:
752 case Bytecodes::_lcmp:
753 case Bytecodes::_dcmpl:
754 case Bytecodes::_dcmpg:
755 case Bytecodes::_ifeq:
756 case Bytecodes::_ifne:
757 case Bytecodes::_iflt:
758 case Bytecodes::_ifge:
759 case Bytecodes::_ifgt:
760 case Bytecodes::_ifle:
761 case Bytecodes::_tableswitch:
762 case Bytecodes::_ireturn:
763 case Bytecodes::_freturn:
764 case Bytecodes::_if_icmpeq:
765 case Bytecodes::_if_icmpne:
766 case Bytecodes::_if_icmplt:
767 case Bytecodes::_if_icmpge:
768 case Bytecodes::_if_icmpgt:
769 case Bytecodes::_if_icmple:
770 case Bytecodes::_lreturn:
771 case Bytecodes::_dreturn:
772 case Bytecodes::_if_acmpeq:
773 case Bytecodes::_if_acmpne:
774 case Bytecodes::_jsr:
775 case Bytecodes::_jsr_w:
776 case Bytecodes::_getstatic:
777 case Bytecodes::_putstatic:
778 case Bytecodes::_getfield:
779 case Bytecodes::_putfield:
780 case Bytecodes::_invokevirtual:
781 case Bytecodes::_invokespecial:
782 case Bytecodes::_invokestatic:
783 case Bytecodes::_invokeinterface:
784 case Bytecodes::_newarray:
785 case Bytecodes::_anewarray:
786 case Bytecodes::_checkcast:
787 case Bytecodes::_arraylength:
788 case Bytecodes::_instanceof:
789 case Bytecodes::_athrow:
790 case Bytecodes::_areturn:
791 case Bytecodes::_monitorenter:
792 case Bytecodes::_monitorexit:
793 case Bytecodes::_ifnull:
794 case Bytecodes::_ifnonnull:
795 case Bytecodes::_multianewarray:
796 case Bytecodes::_lookupswitch:
797 // These bytecodes have no effect on the method's locals.
798 break;
799
800 case Bytecodes::_return:
801 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) {
802 // return from Object.init implicitly registers a finalizer
803 // for the receiver if needed, so keep it alive.
804 load_one(0);
805 }
806 break;
807
808
809 case Bytecodes::_lload:
810 case Bytecodes::_dload:
811 load_two(instruction->get_index());
812 break;
813
814 case Bytecodes::_lload_0:
815 case Bytecodes::_dload_0:
816 load_two(0);
817 break;
818
819 case Bytecodes::_lload_1:
820 case Bytecodes::_dload_1:
821 load_two(1);
822 break;
823
824 case Bytecodes::_lload_2:
825 case Bytecodes::_dload_2:
826 load_two(2);
827 break;
828
829 case Bytecodes::_lload_3:
830 case Bytecodes::_dload_3:
831 load_two(3);
832 break;
833
834 case Bytecodes::_iload:
835 case Bytecodes::_iinc:
836 case Bytecodes::_fload:
837 case Bytecodes::_aload:
838 case Bytecodes::_ret:
839 load_one(instruction->get_index());
840 break;
841
842 case Bytecodes::_iload_0:
843 case Bytecodes::_fload_0:
844 case Bytecodes::_aload_0:
845 load_one(0);
846 break;
847
848 case Bytecodes::_iload_1:
849 case Bytecodes::_fload_1:
850 case Bytecodes::_aload_1:
851 load_one(1);
852 break;
853
854 case Bytecodes::_iload_2:
855 case Bytecodes::_fload_2:
856 case Bytecodes::_aload_2:
857 load_one(2);
858 break;
859
860 case Bytecodes::_iload_3:
861 case Bytecodes::_fload_3:
862 case Bytecodes::_aload_3:
863 load_one(3);
864 break;
865
866 case Bytecodes::_lstore:
867 case Bytecodes::_dstore:
868 store_two(localNum = instruction->get_index());
869 break;
870
871 case Bytecodes::_lstore_0:
872 case Bytecodes::_dstore_0:
873 store_two(0);
874 break;
875
876 case Bytecodes::_lstore_1:
877 case Bytecodes::_dstore_1:
878 store_two(1);
879 break;
880
881 case Bytecodes::_lstore_2:
882 case Bytecodes::_dstore_2:
883 store_two(2);
884 break;
885
886 case Bytecodes::_lstore_3:
887 case Bytecodes::_dstore_3:
888 store_two(3);
889 break;
890
891 case Bytecodes::_istore:
892 case Bytecodes::_fstore:
893 case Bytecodes::_astore:
894 store_one(instruction->get_index());
895 break;
896
897 case Bytecodes::_istore_0:
898 case Bytecodes::_fstore_0:
899 case Bytecodes::_astore_0:
900 store_one(0);
901 break;
902
903 case Bytecodes::_istore_1:
904 case Bytecodes::_fstore_1:
905 case Bytecodes::_astore_1:
906 store_one(1);
907 break;
908
909 case Bytecodes::_istore_2:
910 case Bytecodes::_fstore_2:
911 case Bytecodes::_astore_2:
912 store_one(2);
913 break;
914
915 case Bytecodes::_istore_3:
916 case Bytecodes::_fstore_3:
917 case Bytecodes::_astore_3:
918 store_one(3);
919 break;
920
921 case Bytecodes::_wide:
922 fatal("Iterator should skip this bytecode");
923 break;
924
925 default:
926 tty->print("unexpected opcode: %d\n", instruction->cur_bc());
927 ShouldNotReachHere();
928 break;
929 }
930 }
931
932 void MethodLiveness::BasicBlock::load_two(int local) {
933 load_one(local);
934 load_one(local+1);
935 }
936
937 void MethodLiveness::BasicBlock::load_one(int local) {
938 if (!_kill.at(local)) {
939 _gen.at_put(local, true);
940 }
941 }
942
943 void MethodLiveness::BasicBlock::store_two(int local) {
944 store_one(local);
945 store_one(local+1);
946 }
947
948 void MethodLiveness::BasicBlock::store_one(int local) {
949 if (!_gen.at(local)) {
950 _kill.at_put(local, true);
951 }
952 }
953
954 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) {
955 // These set operations could be combined for efficiency if the
956 // performance of this analysis becomes an issue.
957 _entry.set_union(_normal_exit);
958 _entry.set_difference(_kill);
959 _entry.set_union(_gen);
960
961 // Note that we merge information from our exceptional successors
962 // just once, rather than at individual bytecodes.
963 _entry.set_union(_exception_exit);
964
965 if (TraceLivenessGen) {
966 tty->print_cr(" ** Visiting block at %d **", start_bci());
967 print_on(tty);
968 }
969
970 int i;
971 for (i=_normal_predecessors->length()-1; i>=0; i--) {
972 BasicBlock *block = _normal_predecessors->at(i);
973 if (block->merge_normal(_entry)) {
974 ml->work_list_add(block);
975 }
976 }
977 for (i=_exception_predecessors->length()-1; i>=0; i--) {
978 BasicBlock *block = _exception_predecessors->at(i);
979 if (block->merge_exception(_entry)) {
980 ml->work_list_add(block);
981 }
982 }
983 }
984
985 bool MethodLiveness::BasicBlock::merge_normal(BitMap other) {
986 return _normal_exit.set_union_with_result(other);
987 }
988
989 bool MethodLiveness::BasicBlock::merge_exception(BitMap other) {
990 return _exception_exit.set_union_with_result(other);
991 }
992
993 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) {
994 MethodLivenessResult answer(NEW_RESOURCE_ARRAY(uintptr_t, _analyzer->bit_map_size_words()),
995 _analyzer->bit_map_size_bits());
996 answer.set_is_valid();
997
998 #ifndef ASSERT
999 if (bci == start_bci()) {
1000 answer.set_from(_entry);
1001 return answer;
1002 }
1003 #endif
1004
1005 #ifdef ASSERT
1006 ResourceMark rm;
1007 BitMap g(_gen.size()); g.set_from(_gen);
1008 BitMap k(_kill.size()); k.set_from(_kill);
1009 #endif
1010 if (_last_bci != bci || trueInDebug) {
1011 ciBytecodeStream bytes(method);
1012 bytes.reset_to_bci(bci);
1013 bytes.set_max_bci(limit_bci());
1014 compute_gen_kill_range(&bytes);
1015 assert(_last_bci != bci ||
1016 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect");
1017 _last_bci = bci;
1018 }
1019
1020 answer.clear();
1021 answer.set_union(_normal_exit);
1022 answer.set_difference(_kill);
1023 answer.set_union(_gen);
1024 answer.set_union(_exception_exit);
1025
1026 #ifdef ASSERT
1027 if (bci == start_bci()) {
1028 assert(answer.is_same(_entry), "optimized answer must be accurate");
1029 }
1030 #endif
1031
1032 return answer;
1033 }
1034
1035 #ifndef PRODUCT
1036
1037 void MethodLiveness::BasicBlock::print_on(outputStream *os) const {
1038 os->print_cr("===================================================================");
1039 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci);
1040 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length());
1041 int i;
1042 for (i=0; i < _normal_predecessors->length(); i++) {
1043 os->print(" %4d", _normal_predecessors->at(i)->start_bci());
1044 }
1045 os->cr();
1046 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length());
1047 for (i=0; i < _exception_predecessors->length(); i++) {
1048 os->print(" %4d", _exception_predecessors->at(i)->start_bci());
1049 }
1050 os->cr();
1051 os->print (" Normal Exit : ");
1052 _normal_exit.print_on(os);
1053 os->print (" Gen : ");
1054 _gen.print_on(os);
1055 os->print (" Kill : ");
1056 _kill.print_on(os);
1057 os->print (" Exception Exit: ");
1058 _exception_exit.print_on(os);
1059 os->print (" Entry : ");
1060 _entry.print_on(os);
1061 }
1062
1063 #endif // PRODUCT