1 /*
2 * Copyright (c) 1998, 2016, 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 "ci/ciMethod.hpp"
27 #include "ci/ciMethodBlocks.hpp"
28 #include "ci/ciStreams.hpp"
29 #include "compiler/methodLiveness.hpp"
30 #include "interpreter/bytecode.hpp"
31 #include "interpreter/bytecodes.hpp"
32 #include "memory/allocation.inline.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "runtime/timerTrace.hpp"
35 #include "utilities/bitMap.inline.hpp"
36
37 // The MethodLiveness class performs a simple liveness analysis on a method
38 // in order to decide which locals are live (that is, will be used again) at
39 // a particular bytecode index (bci).
40 //
41 // The algorithm goes:
42 //
43 // 1. Break the method into a set of basic blocks. For each basic block we
44 // also keep track of its set of predecessors through normal control flow
45 // and predecessors through exceptional control flow.
46 //
47 // 2. For each basic block, compute two sets, gen (the set of values used before
48 // they are defined) and kill (the set of values defined before they are used)
49 // in the basic block. A basic block "needs" the locals in its gen set to
50 // perform its computation. A basic block "provides" values for the locals in
51 // its kill set, allowing a need from a successor to be ignored.
52 //
53 // 3. Liveness information (the set of locals which are needed) is pushed backwards through
54 // the program, from blocks to their predecessors. We compute and store liveness
55 // information for the normal/exceptional exit paths for each basic block. When
56 // this process reaches a fixed point, we are done.
57 //
58 // 4. When we are asked about the liveness at a particular bci with a basic block, we
59 // compute gen/kill sets which represent execution from that bci to the exit of
60 // its blocks. We then compose this range gen/kill information with the normal
61 // and exceptional exit information for the block to produce liveness information
62 // at that bci.
63 //
64 // The algorithm is approximate in many respects. Notably:
65 //
66 // 1. We do not do the analysis necessary to match jsr's with the appropriate ret.
67 // Instead we make the conservative assumption that any ret can return to any
68 // jsr return site.
69 // 2. Instead of computing the effects of exceptions at every instruction, we
70 // summarize the effects of all exceptional continuations from the block as
71 // a single set (_exception_exit), losing some information but simplifying the
72 // analysis.
73
74
75 //--------------------------------------------------------------------------
76 // The BitCounter class is used for counting the number of bits set in
77 // some BitMap. It is only used when collecting liveness statistics.
78
79 #ifndef PRODUCT
80
81 class BitCounter: public BitMapClosure {
82 private:
83 int _count;
84 public:
85 BitCounter() : _count(0) {}
86
87 // Callback when bit in map is set
88 virtual bool do_bit(size_t offset) {
89 _count++;
90 return true;
91 }
92
93 int count() {
94 return _count;
95 }
96 };
97
98
99 //--------------------------------------------------------------------------
100
101
102 // Counts
103 long MethodLiveness::_total_bytes = 0;
104 int MethodLiveness::_total_methods = 0;
105
106 long MethodLiveness::_total_blocks = 0;
107 int MethodLiveness::_max_method_blocks = 0;
108
109 long MethodLiveness::_total_edges = 0;
110 int MethodLiveness::_max_block_edges = 0;
111
112 long MethodLiveness::_total_exc_edges = 0;
113 int MethodLiveness::_max_block_exc_edges = 0;
114
115 long MethodLiveness::_total_method_locals = 0;
116 int MethodLiveness::_max_method_locals = 0;
117
118 long MethodLiveness::_total_locals_queried = 0;
119 long MethodLiveness::_total_live_locals_queried = 0;
120
121 long MethodLiveness::_total_visits = 0;
122
123 #endif
124
125 // Timers
126 elapsedTimer MethodLiveness::_time_build_graph;
127 elapsedTimer MethodLiveness::_time_gen_kill;
128 elapsedTimer MethodLiveness::_time_flow;
129 elapsedTimer MethodLiveness::_time_query;
130 elapsedTimer MethodLiveness::_time_total;
131
132 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method)
133 #ifdef COMPILER1
134 : _bci_block_start(arena, method->code_size())
135 #endif
136 {
137 _arena = arena;
138 _method = method;
139 _bit_map_size_bits = method->max_locals();
140 }
141
142 void MethodLiveness::compute_liveness() {
143 #ifndef PRODUCT
144 if (TraceLivenessGen) {
145 tty->print_cr("################################################################");
146 tty->print("# Computing liveness information for ");
147 method()->print_short_name();
148 }
149
150 if (TimeLivenessAnalysis) _time_total.start();
151 #endif
152
153 {
154 TraceTime buildGraph(NULL, &_time_build_graph, TimeLivenessAnalysis);
155 init_basic_blocks();
156 }
157 {
158 TraceTime genKill(NULL, &_time_gen_kill, TimeLivenessAnalysis);
159 init_gen_kill();
160 }
161 {
162 TraceTime flow(NULL, &_time_flow, TimeLivenessAnalysis);
163 propagate_liveness();
164 }
165
166 #ifndef PRODUCT
167 if (TimeLivenessAnalysis) _time_total.stop();
168
169 if (TimeLivenessAnalysis) {
170 // Collect statistics
171 _total_bytes += method()->code_size();
172 _total_methods++;
173
174 int num_blocks = _block_count;
175 _total_blocks += num_blocks;
176 _max_method_blocks = MAX2(num_blocks,_max_method_blocks);
177
178 for (int i=0; i<num_blocks; i++) {
179 BasicBlock *block = _block_list[i];
180
181 int numEdges = block->_normal_predecessors->length();
182 int numExcEdges = block->_exception_predecessors->length();
183
184 _total_edges += numEdges;
185 _total_exc_edges += numExcEdges;
186 _max_block_edges = MAX2(numEdges,_max_block_edges);
187 _max_block_exc_edges = MAX2(numExcEdges,_max_block_exc_edges);
188 }
189
190 int numLocals = _bit_map_size_bits;
191 _total_method_locals += numLocals;
192 _max_method_locals = MAX2(numLocals,_max_method_locals);
193 }
194 #endif
195 }
196
197
198 void MethodLiveness::init_basic_blocks() {
199 bool bailout = false;
200
201 int method_len = method()->code_size();
202 ciMethodBlocks *mblocks = method()->get_method_blocks();
203
204 // Create an array to store the bci->BasicBlock mapping.
205 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL);
206
207 _block_count = mblocks->num_blocks();
208 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count);
209
210 // Used for patching up jsr/ret control flow.
211 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5);
212 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5);
213
214 // generate our block list from ciMethodBlocks
215 for (int blk = 0; blk < _block_count; blk++) {
216 ciBlock *cib = mblocks->block(blk);
217 int start_bci = cib->start_bci();
218 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci());
219 _block_map->at_put(start_bci, _block_list[blk]);
220 #ifdef COMPILER1
221 // mark all bcis where a new basic block starts
222 _bci_block_start.set_bit(start_bci);
223 #endif // COMPILER1
224 }
225 // fill in the predecessors of blocks
226 ciBytecodeStream bytes(method());
227
228 for (int blk = 0; blk < _block_count; blk++) {
229 BasicBlock *current_block = _block_list[blk];
230 int bci = mblocks->block(blk)->control_bci();
231
232 if (bci == ciBlock::fall_through_bci) {
233 int limit = current_block->limit_bci();
234 if (limit < method_len) {
235 BasicBlock *next = _block_map->at(limit);
236 assert( next != NULL, "must be a block immediately following this one.");
237 next->add_normal_predecessor(current_block);
238 }
239 continue;
240 }
241 bytes.reset_to_bci(bci);
242 Bytecodes::Code code = bytes.next();
243 BasicBlock *dest;
244
245 // Now we need to interpret the instruction's effect
246 // on control flow.
247 assert (current_block != NULL, "we must have a current block");
248 switch (code) {
249 case Bytecodes::_ifeq:
250 case Bytecodes::_ifne:
251 case Bytecodes::_iflt:
252 case Bytecodes::_ifge:
253 case Bytecodes::_ifgt:
254 case Bytecodes::_ifle:
255 case Bytecodes::_if_icmpeq:
256 case Bytecodes::_if_icmpne:
257 case Bytecodes::_if_icmplt:
258 case Bytecodes::_if_icmpge:
259 case Bytecodes::_if_icmpgt:
260 case Bytecodes::_if_icmple:
261 case Bytecodes::_if_acmpeq:
262 case Bytecodes::_if_acmpne:
263 case Bytecodes::_ifnull:
264 case Bytecodes::_ifnonnull:
265 // Two way branch. Set predecessors at each destination.
266 dest = _block_map->at(bytes.next_bci());
267 assert(dest != NULL, "must be a block immediately following this one.");
268 dest->add_normal_predecessor(current_block);
269
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:
275 dest = _block_map->at(bytes.get_dest());
276 assert(dest != NULL, "branch desination must start a block.");
277 dest->add_normal_predecessor(current_block);
278 break;
279 case Bytecodes::_goto_w:
280 dest = _block_map->at(bytes.get_far_dest());
281 assert(dest != NULL, "branch desination must start a block.");
282 dest->add_normal_predecessor(current_block);
283 break;
284 case Bytecodes::_tableswitch:
285 {
286 Bytecode_tableswitch tableswitch(&bytes);
287
288 int len = tableswitch.length();
289
290 dest = _block_map->at(bci + tableswitch.default_offset());
291 assert(dest != NULL, "branch desination must start a block.");
292 dest->add_normal_predecessor(current_block);
293 while (--len >= 0) {
294 dest = _block_map->at(bci + tableswitch.dest_offset_at(len));
295 assert(dest != NULL, "branch desination must start a block.");
296 dest->add_normal_predecessor(current_block);
297 }
298 break;
299 }
300
301 case Bytecodes::_lookupswitch:
302 {
303 Bytecode_lookupswitch lookupswitch(&bytes);
304
305 int npairs = lookupswitch.number_of_pairs();
306
307 dest = _block_map->at(bci + lookupswitch.default_offset());
308 assert(dest != NULL, "branch desination must start a block.");
309 dest->add_normal_predecessor(current_block);
310 while(--npairs >= 0) {
311 LookupswitchPair pair = lookupswitch.pair_at(npairs);
312 dest = _block_map->at( bci + pair.offset());
313 assert(dest != NULL, "branch desination must start a block.");
314 dest->add_normal_predecessor(current_block);
315 }
316 break;
317 }
318
319 case Bytecodes::_jsr:
320 {
321 assert(bytes.is_wide()==false, "sanity check");
322 dest = _block_map->at(bytes.get_dest());
323 assert(dest != NULL, "branch desination must start a block.");
324 dest->add_normal_predecessor(current_block);
325 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
326 assert(jsrExit != NULL, "jsr return bci must start a block.");
327 jsr_exit_list->append(jsrExit);
328 break;
329 }
330 case Bytecodes::_jsr_w:
331 {
332 dest = _block_map->at(bytes.get_far_dest());
333 assert(dest != NULL, "branch desination must start a block.");
334 dest->add_normal_predecessor(current_block);
335 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
336 assert(jsrExit != NULL, "jsr return bci must start a block.");
337 jsr_exit_list->append(jsrExit);
338 break;
339 }
340
341 case Bytecodes::_wide:
342 assert(false, "wide opcodes should not be seen here");
343 break;
344 case Bytecodes::_athrow:
345 case Bytecodes::_ireturn:
346 case Bytecodes::_lreturn:
347 case Bytecodes::_freturn:
348 case Bytecodes::_dreturn:
349 case Bytecodes::_areturn:
350 case Bytecodes::_return:
351 // These opcodes are not the normal predecessors of any other opcodes.
352 break;
353 case Bytecodes::_ret:
354 // We will patch up jsr/rets in a subsequent pass.
355 ret_list->append(current_block);
356 break;
357 case Bytecodes::_breakpoint:
358 // Bail out of there are breakpoints in here.
359 bailout = true;
360 break;
361 default:
362 // Do nothing.
363 break;
364 }
365 }
366 // Patch up the jsr/ret's. We conservatively assume that any ret
367 // can return to any jsr site.
368 int ret_list_len = ret_list->length();
369 int jsr_exit_list_len = jsr_exit_list->length();
370 if (ret_list_len > 0 && jsr_exit_list_len > 0) {
371 for (int i = jsr_exit_list_len - 1; i >= 0; i--) {
372 BasicBlock *jsrExit = jsr_exit_list->at(i);
373 for (int i = ret_list_len - 1; i >= 0; i--) {
374 jsrExit->add_normal_predecessor(ret_list->at(i));
375 }
376 }
377 }
378
379 // Compute exception edges.
380 for (int b=_block_count-1; b >= 0; b--) {
381 BasicBlock *block = _block_list[b];
382 int block_start = block->start_bci();
383 int block_limit = block->limit_bci();
384 ciExceptionHandlerStream handlers(method());
385 for (; !handlers.is_done(); handlers.next()) {
386 ciExceptionHandler* handler = handlers.handler();
387 int start = handler->start();
388 int limit = handler->limit();
389 int handler_bci = handler->handler_bci();
390
391 int intersect_start = MAX2(block_start, start);
392 int intersect_limit = MIN2(block_limit, limit);
393 if (intersect_start < intersect_limit) {
394 // The catch range has a nonempty intersection with this
395 // basic block. That means this basic block can be an
396 // exceptional predecessor.
397 _block_map->at(handler_bci)->add_exception_predecessor(block);
398
399 if (handler->is_catch_all()) {
400 // This is a catch-all block.
401 if (intersect_start == block_start && intersect_limit == block_limit) {
402 // The basic block is entirely contained in this catch-all block.
403 // Skip the rest of the exception handlers -- they can never be
404 // reached in execution.
405 break;
406 }
407 }
408 }
409 }
410 }
411 }
412
413 void MethodLiveness::init_gen_kill() {
414 for (int i=_block_count-1; i >= 0; i--) {
415 _block_list[i]->compute_gen_kill(method());
416 }
417 }
418
419 void MethodLiveness::propagate_liveness() {
420 int num_blocks = _block_count;
421 BasicBlock *block;
422
423 // We start our work list off with all blocks in it.
424 // Alternately, we could start off the work list with the list of all
425 // blocks which could exit the method directly, along with one block
426 // from any infinite loop. If this matters, it can be changed. It
427 // may not be clear from looking at the code, but the order of the
428 // workList will be the opposite of the creation order of the basic
429 // blocks, which should be decent for quick convergence (with the
430 // possible exception of exception handlers, which are all created
431 // early).
432 _work_list = NULL;
433 for (int i = 0; i < num_blocks; i++) {
434 block = _block_list[i];
435 block->set_next(_work_list);
436 block->set_on_work_list(true);
437 _work_list = block;
438 }
439
440
441 while ((block = work_list_get()) != NULL) {
442 block->propagate(this);
443 NOT_PRODUCT(_total_visits++;)
444 }
445 }
446
447 void MethodLiveness::work_list_add(BasicBlock *block) {
448 if (!block->on_work_list()) {
449 block->set_next(_work_list);
450 block->set_on_work_list(true);
451 _work_list = block;
452 }
453 }
454
455 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() {
456 BasicBlock *block = _work_list;
457 if (block != NULL) {
458 block->set_on_work_list(false);
459 _work_list = block->next();
460 }
461 return block;
462 }
463
464
465 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) {
466 int bci = entry_bci;
467 bool is_entry = false;
468 if (entry_bci == InvocationEntryBci) {
469 is_entry = true;
470 bci = 0;
471 }
472
473 MethodLivenessResult answer;
474
475 if (_block_count > 0) {
476 if (TimeLivenessAnalysis) _time_total.start();
477 if (TimeLivenessAnalysis) _time_query.start();
478
479 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" );
480 BasicBlock *block = _block_map->at(bci);
481 // We may not be at the block start, so search backwards to find the block
482 // containing bci.
483 int t = bci;
484 while (block == NULL && t > 0) {
485 block = _block_map->at(--t);
486 }
487 assert( block != NULL, "invalid bytecode index; must be instruction index" );
488 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci.");
489
490 answer = block->get_liveness_at(method(), bci);
491
492 if (is_entry && method()->is_synchronized() && !method()->is_static()) {
493 // Synchronized methods use the receiver once on entry.
494 answer.at_put(0, true);
495 }
496
497 #ifndef PRODUCT
498 if (TraceLivenessQuery) {
499 tty->print("Liveness query of ");
500 method()->print_short_name();
501 tty->print(" @ %d : result is ", bci);
502 answer.print_on(tty);
503 }
504
505 if (TimeLivenessAnalysis) _time_query.stop();
506 if (TimeLivenessAnalysis) _time_total.stop();
507 #endif
508 }
509
510 #ifndef PRODUCT
511 if (TimeLivenessAnalysis) {
512 // Collect statistics.
513 _total_locals_queried += _bit_map_size_bits;
514 BitCounter counter;
515 answer.iterate(&counter);
516 _total_live_locals_queried += counter.count();
517 }
518 #endif
519
520 return answer;
521 }
522
523
524 #ifndef PRODUCT
525
526 void MethodLiveness::print_times() {
527 tty->print_cr ("Accumulated liveness analysis times/statistics:");
528 tty->print_cr ("-----------------------------------------------");
529 tty->print_cr (" Total : %3.3f sec.", _time_total.seconds());
530 tty->print_cr (" Build graph : %3.3f sec. (%2.2f%%)", _time_build_graph.seconds(),
531 _time_build_graph.seconds() * 100 / _time_total.seconds());
532 tty->print_cr (" Gen / Kill : %3.3f sec. (%2.2f%%)", _time_gen_kill.seconds(),
533 _time_gen_kill.seconds() * 100 / _time_total.seconds());
534 tty->print_cr (" Dataflow : %3.3f sec. (%2.2f%%)", _time_flow.seconds(),
535 _time_flow.seconds() * 100 / _time_total.seconds());
536 tty->print_cr (" Query : %3.3f sec. (%2.2f%%)", _time_query.seconds(),
537 _time_query.seconds() * 100 / _time_total.seconds());
538 tty->print_cr (" #bytes : %8ld (%3.0f bytes per sec)",
539 _total_bytes,
540 _total_bytes / _time_total.seconds());
541 tty->print_cr (" #methods : %8d (%3.0f methods per sec)",
542 _total_methods,
543 _total_methods / _time_total.seconds());
544 tty->print_cr (" avg locals : %3.3f max locals : %3d",
545 (float)_total_method_locals / _total_methods,
546 _max_method_locals);
547 tty->print_cr (" avg blocks : %3.3f max blocks : %3d",
548 (float)_total_blocks / _total_methods,
549 _max_method_blocks);
550 tty->print_cr (" avg bytes : %3.3f",
551 (float)_total_bytes / _total_methods);
552 tty->print_cr (" #blocks : %8ld",
553 _total_blocks);
554 tty->print_cr (" avg normal predecessors : %3.3f max normal predecessors : %3d",
555 (float)_total_edges / _total_blocks,
556 _max_block_edges);
557 tty->print_cr (" avg exception predecessors : %3.3f max exception predecessors : %3d",
558 (float)_total_exc_edges / _total_blocks,
559 _max_block_exc_edges);
560 tty->print_cr (" avg visits : %3.3f",
561 (float)_total_visits / _total_blocks);
562 tty->print_cr (" #locals queried : %8ld #live : %8ld %%live : %2.2f%%",
563 _total_locals_queried,
564 _total_live_locals_queried,
565 100.0 * _total_live_locals_queried / _total_locals_queried);
566 }
567
568 #endif
569
570
571 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) :
572 _gen(analyzer->arena(), analyzer->bit_map_size_bits()),
573 _kill(analyzer->arena(), analyzer->bit_map_size_bits()),
574 _entry(analyzer->arena(), analyzer->bit_map_size_bits()),
575 _normal_exit(analyzer->arena(), analyzer->bit_map_size_bits()),
576 _exception_exit(analyzer->arena(), analyzer->bit_map_size_bits()),
577 _last_bci(-1) {
578 _analyzer = analyzer;
579 _start_bci = start;
580 _limit_bci = limit;
581 _normal_predecessors =
582 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
583 _exception_predecessors =
584 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
585 }
586
587
588
589 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) {
590 int start = _start_bci;
591 int limit = _limit_bci;
592
593 if (TraceLivenessGen) {
594 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci);
595 }
596
597 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors;
598
599 assert (start < split_bci && split_bci < limit, "improper split");
600
601 // Make a new block to cover the first half of the range.
602 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci);
603
604 // Assign correct values to the second half (this)
605 _normal_predecessors = first_half->_normal_predecessors;
606 _start_bci = split_bci;
607 add_normal_predecessor(first_half);
608
609 // Assign correct predecessors to the new first half
610 first_half->_normal_predecessors = save_predecessors;
611
612 return first_half;
613 }
614
615 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) {
616 ciBytecodeStream bytes(method);
617 bytes.reset_to_bci(start_bci());
618 bytes.set_max_bci(limit_bci());
619 compute_gen_kill_range(&bytes);
620
621 }
622
623 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) {
624 _gen.clear();
625 _kill.clear();
626
627 while (bytes->next() != ciBytecodeStream::EOBC()) {
628 compute_gen_kill_single(bytes);
629 }
630 }
631
632 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) {
633 int localNum;
634
635 // We prohibit _gen and _kill from having locals in common. If we
636 // know that one is definitely going to be applied before the other,
637 // we could save some computation time by relaxing this prohibition.
638
639 switch (instruction->cur_bc()) {
640 case Bytecodes::_nop:
641 case Bytecodes::_goto:
642 case Bytecodes::_goto_w:
643 case Bytecodes::_aconst_null:
644 case Bytecodes::_new:
645 case Bytecodes::_defaultvalue:
646 case Bytecodes::_withfield:
647 case Bytecodes::_iconst_m1:
648 case Bytecodes::_iconst_0:
649 case Bytecodes::_iconst_1:
650 case Bytecodes::_iconst_2:
651 case Bytecodes::_iconst_3:
652 case Bytecodes::_iconst_4:
653 case Bytecodes::_iconst_5:
654 case Bytecodes::_fconst_0:
655 case Bytecodes::_fconst_1:
656 case Bytecodes::_fconst_2:
657 case Bytecodes::_bipush:
658 case Bytecodes::_sipush:
659 case Bytecodes::_lconst_0:
660 case Bytecodes::_lconst_1:
661 case Bytecodes::_dconst_0:
662 case Bytecodes::_dconst_1:
663 case Bytecodes::_ldc2_w:
664 case Bytecodes::_ldc:
665 case Bytecodes::_ldc_w:
666 case Bytecodes::_iaload:
667 case Bytecodes::_faload:
668 case Bytecodes::_baload:
669 case Bytecodes::_caload:
670 case Bytecodes::_saload:
671 case Bytecodes::_laload:
672 case Bytecodes::_daload:
673 case Bytecodes::_aaload:
674 case Bytecodes::_iastore:
675 case Bytecodes::_fastore:
676 case Bytecodes::_bastore:
677 case Bytecodes::_castore:
678 case Bytecodes::_sastore:
679 case Bytecodes::_lastore:
680 case Bytecodes::_dastore:
681 case Bytecodes::_aastore:
682 case Bytecodes::_pop:
683 case Bytecodes::_pop2:
684 case Bytecodes::_dup:
685 case Bytecodes::_dup_x1:
686 case Bytecodes::_dup_x2:
687 case Bytecodes::_dup2:
688 case Bytecodes::_dup2_x1:
689 case Bytecodes::_dup2_x2:
690 case Bytecodes::_swap:
691 case Bytecodes::_iadd:
692 case Bytecodes::_fadd:
693 case Bytecodes::_isub:
694 case Bytecodes::_fsub:
695 case Bytecodes::_imul:
696 case Bytecodes::_fmul:
697 case Bytecodes::_idiv:
698 case Bytecodes::_fdiv:
699 case Bytecodes::_irem:
700 case Bytecodes::_frem:
701 case Bytecodes::_ishl:
702 case Bytecodes::_ishr:
703 case Bytecodes::_iushr:
704 case Bytecodes::_iand:
705 case Bytecodes::_ior:
706 case Bytecodes::_ixor:
707 case Bytecodes::_l2f:
708 case Bytecodes::_l2i:
709 case Bytecodes::_d2f:
710 case Bytecodes::_d2i:
711 case Bytecodes::_fcmpl:
712 case Bytecodes::_fcmpg:
713 case Bytecodes::_ladd:
714 case Bytecodes::_dadd:
715 case Bytecodes::_lsub:
716 case Bytecodes::_dsub:
717 case Bytecodes::_lmul:
718 case Bytecodes::_dmul:
719 case Bytecodes::_ldiv:
720 case Bytecodes::_ddiv:
721 case Bytecodes::_lrem:
722 case Bytecodes::_drem:
723 case Bytecodes::_land:
724 case Bytecodes::_lor:
725 case Bytecodes::_lxor:
726 case Bytecodes::_ineg:
727 case Bytecodes::_fneg:
728 case Bytecodes::_i2f:
729 case Bytecodes::_f2i:
730 case Bytecodes::_i2c:
731 case Bytecodes::_i2s:
732 case Bytecodes::_i2b:
733 case Bytecodes::_lneg:
734 case Bytecodes::_dneg:
735 case Bytecodes::_l2d:
736 case Bytecodes::_d2l:
737 case Bytecodes::_lshl:
738 case Bytecodes::_lshr:
739 case Bytecodes::_lushr:
740 case Bytecodes::_i2l:
741 case Bytecodes::_i2d:
742 case Bytecodes::_f2l:
743 case Bytecodes::_f2d:
744 case Bytecodes::_lcmp:
745 case Bytecodes::_dcmpl:
746 case Bytecodes::_dcmpg:
747 case Bytecodes::_ifeq:
748 case Bytecodes::_ifne:
749 case Bytecodes::_iflt:
750 case Bytecodes::_ifge:
751 case Bytecodes::_ifgt:
752 case Bytecodes::_ifle:
753 case Bytecodes::_tableswitch:
754 case Bytecodes::_ireturn:
755 case Bytecodes::_freturn:
756 case Bytecodes::_if_icmpeq:
757 case Bytecodes::_if_icmpne:
758 case Bytecodes::_if_icmplt:
759 case Bytecodes::_if_icmpge:
760 case Bytecodes::_if_icmpgt:
761 case Bytecodes::_if_icmple:
762 case Bytecodes::_lreturn:
763 case Bytecodes::_dreturn:
764 case Bytecodes::_if_acmpeq:
765 case Bytecodes::_if_acmpne:
766 case Bytecodes::_jsr:
767 case Bytecodes::_jsr_w:
768 case Bytecodes::_getstatic:
769 case Bytecodes::_putstatic:
770 case Bytecodes::_getfield:
771 case Bytecodes::_putfield:
772 case Bytecodes::_invokevirtual:
773 case Bytecodes::_invokespecial:
774 case Bytecodes::_invokestatic:
775 case Bytecodes::_invokeinterface:
776 case Bytecodes::_invokedynamic:
777 case Bytecodes::_newarray:
778 case Bytecodes::_anewarray:
779 case Bytecodes::_checkcast:
780 case Bytecodes::_arraylength:
781 case Bytecodes::_instanceof:
782 case Bytecodes::_athrow:
783 case Bytecodes::_areturn:
784 case Bytecodes::_monitorenter:
785 case Bytecodes::_monitorexit:
786 case Bytecodes::_ifnull:
787 case Bytecodes::_ifnonnull:
788 case Bytecodes::_multianewarray:
789 case Bytecodes::_lookupswitch:
790 // These bytecodes have no effect on the method's locals.
791 break;
792
793 case Bytecodes::_return:
794 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) {
795 // return from Object.init implicitly registers a finalizer
796 // for the receiver if needed, so keep it alive.
797 load_one(0);
798 }
799 break;
800
801
802 case Bytecodes::_lload:
803 case Bytecodes::_dload:
804 load_two(instruction->get_index());
805 break;
806
807 case Bytecodes::_lload_0:
808 case Bytecodes::_dload_0:
809 load_two(0);
810 break;
811
812 case Bytecodes::_lload_1:
813 case Bytecodes::_dload_1:
814 load_two(1);
815 break;
816
817 case Bytecodes::_lload_2:
818 case Bytecodes::_dload_2:
819 load_two(2);
820 break;
821
822 case Bytecodes::_lload_3:
823 case Bytecodes::_dload_3:
824 load_two(3);
825 break;
826
827 case Bytecodes::_iload:
828 case Bytecodes::_iinc:
829 case Bytecodes::_fload:
830 case Bytecodes::_aload:
831 case Bytecodes::_ret:
832 load_one(instruction->get_index());
833 break;
834
835 case Bytecodes::_iload_0:
836 case Bytecodes::_fload_0:
837 case Bytecodes::_aload_0:
838 load_one(0);
839 break;
840
841 case Bytecodes::_iload_1:
842 case Bytecodes::_fload_1:
843 case Bytecodes::_aload_1:
844 load_one(1);
845 break;
846
847 case Bytecodes::_iload_2:
848 case Bytecodes::_fload_2:
849 case Bytecodes::_aload_2:
850 load_one(2);
851 break;
852
853 case Bytecodes::_iload_3:
854 case Bytecodes::_fload_3:
855 case Bytecodes::_aload_3:
856 load_one(3);
857 break;
858
859 case Bytecodes::_lstore:
860 case Bytecodes::_dstore:
861 store_two(localNum = instruction->get_index());
862 break;
863
864 case Bytecodes::_lstore_0:
865 case Bytecodes::_dstore_0:
866 store_two(0);
867 break;
868
869 case Bytecodes::_lstore_1:
870 case Bytecodes::_dstore_1:
871 store_two(1);
872 break;
873
874 case Bytecodes::_lstore_2:
875 case Bytecodes::_dstore_2:
876 store_two(2);
877 break;
878
879 case Bytecodes::_lstore_3:
880 case Bytecodes::_dstore_3:
881 store_two(3);
882 break;
883
884 case Bytecodes::_istore:
885 case Bytecodes::_fstore:
886 case Bytecodes::_astore:
887 store_one(instruction->get_index());
888 break;
889
890 case Bytecodes::_istore_0:
891 case Bytecodes::_fstore_0:
892 case Bytecodes::_astore_0:
893 store_one(0);
894 break;
895
896 case Bytecodes::_istore_1:
897 case Bytecodes::_fstore_1:
898 case Bytecodes::_astore_1:
899 store_one(1);
900 break;
901
902 case Bytecodes::_istore_2:
903 case Bytecodes::_fstore_2:
904 case Bytecodes::_astore_2:
905 store_one(2);
906 break;
907
908 case Bytecodes::_istore_3:
909 case Bytecodes::_fstore_3:
910 case Bytecodes::_astore_3:
911 store_one(3);
912 break;
913
914 case Bytecodes::_wide:
915 fatal("Iterator should skip this bytecode");
916 break;
917
918 default:
919 tty->print("unexpected opcode: %d\n", instruction->cur_bc());
920 ShouldNotReachHere();
921 break;
922 }
923 }
924
925 void MethodLiveness::BasicBlock::load_two(int local) {
926 load_one(local);
927 load_one(local+1);
928 }
929
930 void MethodLiveness::BasicBlock::load_one(int local) {
931 if (!_kill.at(local)) {
932 _gen.at_put(local, true);
933 }
934 }
935
936 void MethodLiveness::BasicBlock::store_two(int local) {
937 store_one(local);
938 store_one(local+1);
939 }
940
941 void MethodLiveness::BasicBlock::store_one(int local) {
942 if (!_gen.at(local)) {
943 _kill.at_put(local, true);
944 }
945 }
946
947 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) {
948 // These set operations could be combined for efficiency if the
949 // performance of this analysis becomes an issue.
950 _entry.set_union(_normal_exit);
951 _entry.set_difference(_kill);
952 _entry.set_union(_gen);
953
954 // Note that we merge information from our exceptional successors
955 // just once, rather than at individual bytecodes.
956 _entry.set_union(_exception_exit);
957
958 if (TraceLivenessGen) {
959 tty->print_cr(" ** Visiting block at %d **", start_bci());
960 print_on(tty);
961 }
962
963 int i;
964 for (i=_normal_predecessors->length()-1; i>=0; i--) {
965 BasicBlock *block = _normal_predecessors->at(i);
966 if (block->merge_normal(_entry)) {
967 ml->work_list_add(block);
968 }
969 }
970 for (i=_exception_predecessors->length()-1; i>=0; i--) {
971 BasicBlock *block = _exception_predecessors->at(i);
972 if (block->merge_exception(_entry)) {
973 ml->work_list_add(block);
974 }
975 }
976 }
977
978 bool MethodLiveness::BasicBlock::merge_normal(const BitMap& other) {
979 return _normal_exit.set_union_with_result(other);
980 }
981
982 bool MethodLiveness::BasicBlock::merge_exception(const BitMap& other) {
983 return _exception_exit.set_union_with_result(other);
984 }
985
986 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) {
987 MethodLivenessResult answer(_analyzer->bit_map_size_bits());
988 answer.set_is_valid();
989
990 #ifndef ASSERT
991 if (bci == start_bci()) {
992 answer.set_from(_entry);
993 return answer;
994 }
995 #endif
996
997 #ifdef ASSERT
998 ResourceMark rm;
999 ResourceBitMap g(_gen.size()); g.set_from(_gen);
1000 ResourceBitMap k(_kill.size()); k.set_from(_kill);
1001 #endif
1002 if (_last_bci != bci || trueInDebug) {
1003 ciBytecodeStream bytes(method);
1004 bytes.reset_to_bci(bci);
1005 bytes.set_max_bci(limit_bci());
1006 compute_gen_kill_range(&bytes);
1007 assert(_last_bci != bci ||
1008 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect");
1009 _last_bci = bci;
1010 }
1011
1012 answer.set_union(_normal_exit);
1013 answer.set_difference(_kill);
1014 answer.set_union(_gen);
1015 answer.set_union(_exception_exit);
1016
1017 #ifdef ASSERT
1018 if (bci == start_bci()) {
1019 assert(answer.is_same(_entry), "optimized answer must be accurate");
1020 }
1021 #endif
1022
1023 return answer;
1024 }
1025
1026 #ifndef PRODUCT
1027
1028 void MethodLiveness::BasicBlock::print_on(outputStream *os) const {
1029 os->print_cr("===================================================================");
1030 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci);
1031 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length());
1032 int i;
1033 for (i=0; i < _normal_predecessors->length(); i++) {
1034 os->print(" %4d", _normal_predecessors->at(i)->start_bci());
1035 }
1036 os->cr();
1037 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length());
1038 for (i=0; i < _exception_predecessors->length(); i++) {
1039 os->print(" %4d", _exception_predecessors->at(i)->start_bci());
1040 }
1041 os->cr();
1042 os->print (" Normal Exit : ");
1043 _normal_exit.print_on(os);
1044 os->print (" Gen : ");
1045 _gen.print_on(os);
1046 os->print (" Kill : ");
1047 _kill.print_on(os);
1048 os->print (" Exception Exit: ");
1049 _exception_exit.print_on(os);
1050 os->print (" Entry : ");
1051 _entry.print_on(os);
1052 }
1053
1054 #endif // PRODUCT