1 /*
2 * Copyright (c) 1998, 2019, 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 "utilities/bitMap.inline.hpp"
35
36 // The MethodLiveness class performs a simple liveness analysis on a method
37 // in order to decide which locals are live (that is, will be used again) at
38 // a particular bytecode index (bci).
39 //
40 // The algorithm goes:
41 //
42 // 1. Break the method into a set of basic blocks. For each basic block we
43 // also keep track of its set of predecessors through normal control flow
44 // and predecessors through exceptional control flow.
45 //
46 // 2. For each basic block, compute two sets, gen (the set of values used before
47 // they are defined) and kill (the set of values defined before they are used)
48 // in the basic block. A basic block "needs" the locals in its gen set to
49 // perform its computation. A basic block "provides" values for the locals in
50 // its kill set, allowing a need from a successor to be ignored.
51 //
52 // 3. Liveness information (the set of locals which are needed) is pushed backwards through
53 // the program, from blocks to their predecessors. We compute and store liveness
54 // information for the normal/exceptional exit paths for each basic block. When
55 // this process reaches a fixed point, we are done.
56 //
57 // 4. When we are asked about the liveness at a particular bci with a basic block, we
58 // compute gen/kill sets which represent execution from that bci to the exit of
59 // its blocks. We then compose this range gen/kill information with the normal
60 // and exceptional exit information for the block to produce liveness information
61 // at that bci.
62 //
63 // The algorithm is approximate in many respects. Notably:
64 //
65 // 1. We do not do the analysis necessary to match jsr's with the appropriate ret.
66 // Instead we make the conservative assumption that any ret can return to any
67 // jsr return site.
68 // 2. Instead of computing the effects of exceptions at every instruction, we
69 // summarize the effects of all exceptional continuations from the block as
70 // a single set (_exception_exit), losing some information but simplifying the
71 // analysis.
72
73 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method)
74 #ifdef COMPILER1
75 : _bci_block_start(arena, method->code_size())
76 #endif
77 {
78 _arena = arena;
79 _method = method;
80 _bit_map_size_bits = method->max_locals();
81 }
82
83 void MethodLiveness::compute_liveness() {
84 #ifndef PRODUCT
85 if (TraceLivenessGen) {
86 tty->print_cr("################################################################");
87 tty->print("# Computing liveness information for ");
88 method()->print_short_name();
89 }
90 #endif
91
92 init_basic_blocks();
93 init_gen_kill();
94 propagate_liveness();
95 }
96
97
98 void MethodLiveness::init_basic_blocks() {
99 bool bailout = false;
100
101 int method_len = method()->code_size();
102 ciMethodBlocks *mblocks = method()->get_method_blocks();
103
104 // Create an array to store the bci->BasicBlock mapping.
105 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL);
106
107 _block_count = mblocks->num_blocks();
108 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count);
109
110 // Used for patching up jsr/ret control flow.
111 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5);
112 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5);
113
114 // generate our block list from ciMethodBlocks
115 for (int blk = 0; blk < _block_count; blk++) {
116 ciBlock *cib = mblocks->block(blk);
117 int start_bci = cib->start_bci();
118 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci());
119 _block_map->at_put(start_bci, _block_list[blk]);
120 #ifdef COMPILER1
121 // mark all bcis where a new basic block starts
122 _bci_block_start.set_bit(start_bci);
123 #endif // COMPILER1
124 }
125 // fill in the predecessors of blocks
126 ciBytecodeStream bytes(method());
127
128 for (int blk = 0; blk < _block_count; blk++) {
129 BasicBlock *current_block = _block_list[blk];
130 int bci = mblocks->block(blk)->control_bci();
131
132 if (bci == ciBlock::fall_through_bci) {
133 int limit = current_block->limit_bci();
134 if (limit < method_len) {
135 BasicBlock *next = _block_map->at(limit);
136 assert( next != NULL, "must be a block immediately following this one.");
137 next->add_normal_predecessor(current_block);
138 }
139 continue;
140 }
141 bytes.reset_to_bci(bci);
142 Bytecodes::Code code = bytes.next();
143 BasicBlock *dest;
144
145 // Now we need to interpret the instruction's effect
146 // on control flow.
147 assert (current_block != NULL, "we must have a current block");
148 switch (code) {
149 case Bytecodes::_ifeq:
150 case Bytecodes::_ifne:
151 case Bytecodes::_iflt:
152 case Bytecodes::_ifge:
153 case Bytecodes::_ifgt:
154 case Bytecodes::_ifle:
155 case Bytecodes::_if_icmpeq:
156 case Bytecodes::_if_icmpne:
157 case Bytecodes::_if_icmplt:
158 case Bytecodes::_if_icmpge:
159 case Bytecodes::_if_icmpgt:
160 case Bytecodes::_if_icmple:
161 case Bytecodes::_if_acmpeq:
162 case Bytecodes::_if_acmpne:
163 case Bytecodes::_ifnull:
164 case Bytecodes::_ifnonnull:
165 // Two way branch. Set predecessors at each destination.
166 dest = _block_map->at(bytes.next_bci());
167 assert(dest != NULL, "must be a block immediately following this one.");
168 dest->add_normal_predecessor(current_block);
169
170 dest = _block_map->at(bytes.get_dest());
171 assert(dest != NULL, "branch desination must start a block.");
172 dest->add_normal_predecessor(current_block);
173 break;
174 case Bytecodes::_goto:
175 dest = _block_map->at(bytes.get_dest());
176 assert(dest != NULL, "branch desination must start a block.");
177 dest->add_normal_predecessor(current_block);
178 break;
179 case Bytecodes::_goto_w:
180 dest = _block_map->at(bytes.get_far_dest());
181 assert(dest != NULL, "branch desination must start a block.");
182 dest->add_normal_predecessor(current_block);
183 break;
184 case Bytecodes::_tableswitch:
185 {
186 Bytecode_tableswitch tableswitch(&bytes);
187
188 int len = tableswitch.length();
189
190 dest = _block_map->at(bci + tableswitch.default_offset());
191 assert(dest != NULL, "branch desination must start a block.");
192 dest->add_normal_predecessor(current_block);
193 while (--len >= 0) {
194 dest = _block_map->at(bci + tableswitch.dest_offset_at(len));
195 assert(dest != NULL, "branch desination must start a block.");
196 dest->add_normal_predecessor(current_block);
197 }
198 break;
199 }
200
201 case Bytecodes::_lookupswitch:
202 {
203 Bytecode_lookupswitch lookupswitch(&bytes);
204
205 int npairs = lookupswitch.number_of_pairs();
206
207 dest = _block_map->at(bci + lookupswitch.default_offset());
208 assert(dest != NULL, "branch desination must start a block.");
209 dest->add_normal_predecessor(current_block);
210 while(--npairs >= 0) {
211 LookupswitchPair pair = lookupswitch.pair_at(npairs);
212 dest = _block_map->at( bci + pair.offset());
213 assert(dest != NULL, "branch desination must start a block.");
214 dest->add_normal_predecessor(current_block);
215 }
216 break;
217 }
218
219 case Bytecodes::_jsr:
220 {
221 assert(bytes.is_wide()==false, "sanity check");
222 dest = _block_map->at(bytes.get_dest());
223 assert(dest != NULL, "branch desination must start a block.");
224 dest->add_normal_predecessor(current_block);
225 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
226 assert(jsrExit != NULL, "jsr return bci must start a block.");
227 jsr_exit_list->append(jsrExit);
228 break;
229 }
230 case Bytecodes::_jsr_w:
231 {
232 dest = _block_map->at(bytes.get_far_dest());
233 assert(dest != NULL, "branch desination must start a block.");
234 dest->add_normal_predecessor(current_block);
235 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
236 assert(jsrExit != NULL, "jsr return bci must start a block.");
237 jsr_exit_list->append(jsrExit);
238 break;
239 }
240
241 case Bytecodes::_wide:
242 assert(false, "wide opcodes should not be seen here");
243 break;
244 case Bytecodes::_athrow:
245 case Bytecodes::_ireturn:
246 case Bytecodes::_lreturn:
247 case Bytecodes::_freturn:
248 case Bytecodes::_dreturn:
249 case Bytecodes::_areturn:
250 case Bytecodes::_return:
251 // These opcodes are not the normal predecessors of any other opcodes.
252 break;
253 case Bytecodes::_ret:
254 // We will patch up jsr/rets in a subsequent pass.
255 ret_list->append(current_block);
256 break;
257 case Bytecodes::_breakpoint:
258 // Bail out of there are breakpoints in here.
259 bailout = true;
260 break;
261 default:
262 // Do nothing.
263 break;
264 }
265 }
266 // Patch up the jsr/ret's. We conservatively assume that any ret
267 // can return to any jsr site.
268 int ret_list_len = ret_list->length();
269 int jsr_exit_list_len = jsr_exit_list->length();
270 if (ret_list_len > 0 && jsr_exit_list_len > 0) {
271 for (int i = jsr_exit_list_len - 1; i >= 0; i--) {
272 BasicBlock *jsrExit = jsr_exit_list->at(i);
273 for (int i = ret_list_len - 1; i >= 0; i--) {
274 jsrExit->add_normal_predecessor(ret_list->at(i));
275 }
276 }
277 }
278
279 // Compute exception edges.
280 for (int b=_block_count-1; b >= 0; b--) {
281 BasicBlock *block = _block_list[b];
282 int block_start = block->start_bci();
283 int block_limit = block->limit_bci();
284 ciExceptionHandlerStream handlers(method());
285 for (; !handlers.is_done(); handlers.next()) {
286 ciExceptionHandler* handler = handlers.handler();
287 int start = handler->start();
288 int limit = handler->limit();
289 int handler_bci = handler->handler_bci();
290
291 int intersect_start = MAX2(block_start, start);
292 int intersect_limit = MIN2(block_limit, limit);
293 if (intersect_start < intersect_limit) {
294 // The catch range has a nonempty intersection with this
295 // basic block. That means this basic block can be an
296 // exceptional predecessor.
297 _block_map->at(handler_bci)->add_exception_predecessor(block);
298
299 if (handler->is_catch_all()) {
300 // This is a catch-all block.
301 if (intersect_start == block_start && intersect_limit == block_limit) {
302 // The basic block is entirely contained in this catch-all block.
303 // Skip the rest of the exception handlers -- they can never be
304 // reached in execution.
305 break;
306 }
307 }
308 }
309 }
310 }
311 }
312
313 void MethodLiveness::init_gen_kill() {
314 for (int i=_block_count-1; i >= 0; i--) {
315 _block_list[i]->compute_gen_kill(method());
316 }
317 }
318
319 void MethodLiveness::propagate_liveness() {
320 int num_blocks = _block_count;
321 BasicBlock *block;
322
323 // We start our work list off with all blocks in it.
324 // Alternately, we could start off the work list with the list of all
325 // blocks which could exit the method directly, along with one block
326 // from any infinite loop. If this matters, it can be changed. It
327 // may not be clear from looking at the code, but the order of the
328 // workList will be the opposite of the creation order of the basic
329 // blocks, which should be decent for quick convergence (with the
330 // possible exception of exception handlers, which are all created
331 // early).
332 _work_list = NULL;
333 for (int i = 0; i < num_blocks; i++) {
334 block = _block_list[i];
335 block->set_next(_work_list);
336 block->set_on_work_list(true);
337 _work_list = block;
338 }
339
340
341 while ((block = work_list_get()) != NULL) {
342 block->propagate(this);
343 }
344 }
345
346 void MethodLiveness::work_list_add(BasicBlock *block) {
347 if (!block->on_work_list()) {
348 block->set_next(_work_list);
349 block->set_on_work_list(true);
350 _work_list = block;
351 }
352 }
353
354 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() {
355 BasicBlock *block = _work_list;
356 if (block != NULL) {
357 block->set_on_work_list(false);
358 _work_list = block->next();
359 }
360 return block;
361 }
362
363
364 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) {
365 int bci = entry_bci;
366 bool is_entry = false;
367 if (entry_bci == InvocationEntryBci) {
368 is_entry = true;
369 bci = 0;
370 }
371
372 MethodLivenessResult answer;
373
374 if (_block_count > 0) {
375
376 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" );
377 BasicBlock *block = _block_map->at(bci);
378 // We may not be at the block start, so search backwards to find the block
379 // containing bci.
380 int t = bci;
381 while (block == NULL && t > 0) {
382 block = _block_map->at(--t);
383 }
384 guarantee(block != NULL, "invalid bytecode index; must be instruction index");
385 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci.");
386
387 answer = block->get_liveness_at(method(), bci);
388
389 if (is_entry && method()->is_synchronized() && !method()->is_static()) {
390 // Synchronized methods use the receiver once on entry.
391 answer.at_put(0, true);
392 }
393
394 #ifndef PRODUCT
395 if (TraceLivenessQuery) {
396 tty->print("Liveness query of ");
397 method()->print_short_name();
398 tty->print(" @ %d : result is ", bci);
399 answer.print_on(tty);
400 }
401 #endif
402 }
403
404 return answer;
405 }
406
407 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) :
408 _entry(analyzer->arena(), analyzer->bit_map_size_bits()),
409 _normal_exit(analyzer->arena(), analyzer->bit_map_size_bits()),
410 _exception_exit(analyzer->arena(), analyzer->bit_map_size_bits()),
411 _gen(analyzer->arena(), analyzer->bit_map_size_bits()),
412 _kill(analyzer->arena(), analyzer->bit_map_size_bits()),
413 _last_bci(-1) {
414 _analyzer = analyzer;
415 _start_bci = start;
416 _limit_bci = limit;
417 _normal_predecessors =
418 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
419 _exception_predecessors =
420 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
421 }
422
423
424
425 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) {
426 int start = _start_bci;
427 int limit = _limit_bci;
428
429 if (TraceLivenessGen) {
430 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci);
431 }
432
433 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors;
434
435 assert (start < split_bci && split_bci < limit, "improper split");
436
437 // Make a new block to cover the first half of the range.
438 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci);
439
440 // Assign correct values to the second half (this)
441 _normal_predecessors = first_half->_normal_predecessors;
442 _start_bci = split_bci;
443 add_normal_predecessor(first_half);
444
445 // Assign correct predecessors to the new first half
446 first_half->_normal_predecessors = save_predecessors;
447
448 return first_half;
449 }
450
451 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) {
452 ciBytecodeStream bytes(method);
453 bytes.reset_to_bci(start_bci());
454 bytes.set_max_bci(limit_bci());
455 compute_gen_kill_range(&bytes);
456
457 }
458
459 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) {
460 _gen.clear();
461 _kill.clear();
462
463 while (bytes->next() != ciBytecodeStream::EOBC()) {
464 compute_gen_kill_single(bytes);
465 }
466 }
467
468 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) {
469 int localNum;
470
471 // We prohibit _gen and _kill from having locals in common. If we
472 // know that one is definitely going to be applied before the other,
473 // we could save some computation time by relaxing this prohibition.
474
475 switch (instruction->cur_bc()) {
476 case Bytecodes::_nop:
477 case Bytecodes::_goto:
478 case Bytecodes::_goto_w:
479 case Bytecodes::_aconst_null:
480 case Bytecodes::_new:
481 case Bytecodes::_iconst_m1:
482 case Bytecodes::_iconst_0:
483 case Bytecodes::_iconst_1:
484 case Bytecodes::_iconst_2:
485 case Bytecodes::_iconst_3:
486 case Bytecodes::_iconst_4:
487 case Bytecodes::_iconst_5:
488 case Bytecodes::_fconst_0:
489 case Bytecodes::_fconst_1:
490 case Bytecodes::_fconst_2:
491 case Bytecodes::_bipush:
492 case Bytecodes::_sipush:
493 case Bytecodes::_lconst_0:
494 case Bytecodes::_lconst_1:
495 case Bytecodes::_dconst_0:
496 case Bytecodes::_dconst_1:
497 case Bytecodes::_ldc2_w:
498 case Bytecodes::_ldc:
499 case Bytecodes::_ldc_w:
500 case Bytecodes::_iaload:
501 case Bytecodes::_faload:
502 case Bytecodes::_baload:
503 case Bytecodes::_caload:
504 case Bytecodes::_saload:
505 case Bytecodes::_laload:
506 case Bytecodes::_daload:
507 case Bytecodes::_aaload:
508 case Bytecodes::_iastore:
509 case Bytecodes::_fastore:
510 case Bytecodes::_bastore:
511 case Bytecodes::_castore:
512 case Bytecodes::_sastore:
513 case Bytecodes::_lastore:
514 case Bytecodes::_dastore:
515 case Bytecodes::_aastore:
516 case Bytecodes::_pop:
517 case Bytecodes::_pop2:
518 case Bytecodes::_dup:
519 case Bytecodes::_dup_x1:
520 case Bytecodes::_dup_x2:
521 case Bytecodes::_dup2:
522 case Bytecodes::_dup2_x1:
523 case Bytecodes::_dup2_x2:
524 case Bytecodes::_swap:
525 case Bytecodes::_iadd:
526 case Bytecodes::_fadd:
527 case Bytecodes::_isub:
528 case Bytecodes::_fsub:
529 case Bytecodes::_imul:
530 case Bytecodes::_fmul:
531 case Bytecodes::_idiv:
532 case Bytecodes::_fdiv:
533 case Bytecodes::_irem:
534 case Bytecodes::_frem:
535 case Bytecodes::_ishl:
536 case Bytecodes::_ishr:
537 case Bytecodes::_iushr:
538 case Bytecodes::_iand:
539 case Bytecodes::_ior:
540 case Bytecodes::_ixor:
541 case Bytecodes::_l2f:
542 case Bytecodes::_l2i:
543 case Bytecodes::_d2f:
544 case Bytecodes::_d2i:
545 case Bytecodes::_fcmpl:
546 case Bytecodes::_fcmpg:
547 case Bytecodes::_ladd:
548 case Bytecodes::_dadd:
549 case Bytecodes::_lsub:
550 case Bytecodes::_dsub:
551 case Bytecodes::_lmul:
552 case Bytecodes::_dmul:
553 case Bytecodes::_ldiv:
554 case Bytecodes::_ddiv:
555 case Bytecodes::_lrem:
556 case Bytecodes::_drem:
557 case Bytecodes::_land:
558 case Bytecodes::_lor:
559 case Bytecodes::_lxor:
560 case Bytecodes::_ineg:
561 case Bytecodes::_fneg:
562 case Bytecodes::_i2f:
563 case Bytecodes::_f2i:
564 case Bytecodes::_i2c:
565 case Bytecodes::_i2s:
566 case Bytecodes::_i2b:
567 case Bytecodes::_lneg:
568 case Bytecodes::_dneg:
569 case Bytecodes::_l2d:
570 case Bytecodes::_d2l:
571 case Bytecodes::_lshl:
572 case Bytecodes::_lshr:
573 case Bytecodes::_lushr:
574 case Bytecodes::_i2l:
575 case Bytecodes::_i2d:
576 case Bytecodes::_f2l:
577 case Bytecodes::_f2d:
578 case Bytecodes::_lcmp:
579 case Bytecodes::_dcmpl:
580 case Bytecodes::_dcmpg:
581 case Bytecodes::_ifeq:
582 case Bytecodes::_ifne:
583 case Bytecodes::_iflt:
584 case Bytecodes::_ifge:
585 case Bytecodes::_ifgt:
586 case Bytecodes::_ifle:
587 case Bytecodes::_tableswitch:
588 case Bytecodes::_ireturn:
589 case Bytecodes::_freturn:
590 case Bytecodes::_if_icmpeq:
591 case Bytecodes::_if_icmpne:
592 case Bytecodes::_if_icmplt:
593 case Bytecodes::_if_icmpge:
594 case Bytecodes::_if_icmpgt:
595 case Bytecodes::_if_icmple:
596 case Bytecodes::_lreturn:
597 case Bytecodes::_dreturn:
598 case Bytecodes::_if_acmpeq:
599 case Bytecodes::_if_acmpne:
600 case Bytecodes::_jsr:
601 case Bytecodes::_jsr_w:
602 case Bytecodes::_getstatic:
603 case Bytecodes::_putstatic:
604 case Bytecodes::_getfield:
605 case Bytecodes::_putfield:
606 case Bytecodes::_invokevirtual:
607 case Bytecodes::_invokespecial:
608 case Bytecodes::_invokestatic:
609 case Bytecodes::_invokeinterface:
610 case Bytecodes::_invokedynamic:
611 case Bytecodes::_newarray:
612 case Bytecodes::_anewarray:
613 case Bytecodes::_checkcast:
614 case Bytecodes::_arraylength:
615 case Bytecodes::_instanceof:
616 case Bytecodes::_athrow:
617 case Bytecodes::_areturn:
618 case Bytecodes::_monitorenter:
619 case Bytecodes::_monitorexit:
620 case Bytecodes::_ifnull:
621 case Bytecodes::_ifnonnull:
622 case Bytecodes::_multianewarray:
623 case Bytecodes::_lookupswitch:
624 // These bytecodes have no effect on the method's locals.
625 break;
626
627 case Bytecodes::_return:
628 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) {
629 // return from Object.init implicitly registers a finalizer
630 // for the receiver if needed, so keep it alive.
631 load_one(0);
632 }
633 break;
634
635
636 case Bytecodes::_lload:
637 case Bytecodes::_dload:
638 load_two(instruction->get_index());
639 break;
640
641 case Bytecodes::_lload_0:
642 case Bytecodes::_dload_0:
643 load_two(0);
644 break;
645
646 case Bytecodes::_lload_1:
647 case Bytecodes::_dload_1:
648 load_two(1);
649 break;
650
651 case Bytecodes::_lload_2:
652 case Bytecodes::_dload_2:
653 load_two(2);
654 break;
655
656 case Bytecodes::_lload_3:
657 case Bytecodes::_dload_3:
658 load_two(3);
659 break;
660
661 case Bytecodes::_iload:
662 case Bytecodes::_iinc:
663 case Bytecodes::_fload:
664 case Bytecodes::_aload:
665 case Bytecodes::_ret:
666 load_one(instruction->get_index());
667 break;
668
669 case Bytecodes::_iload_0:
670 case Bytecodes::_fload_0:
671 case Bytecodes::_aload_0:
672 load_one(0);
673 break;
674
675 case Bytecodes::_iload_1:
676 case Bytecodes::_fload_1:
677 case Bytecodes::_aload_1:
678 load_one(1);
679 break;
680
681 case Bytecodes::_iload_2:
682 case Bytecodes::_fload_2:
683 case Bytecodes::_aload_2:
684 load_one(2);
685 break;
686
687 case Bytecodes::_iload_3:
688 case Bytecodes::_fload_3:
689 case Bytecodes::_aload_3:
690 load_one(3);
691 break;
692
693 case Bytecodes::_lstore:
694 case Bytecodes::_dstore:
695 store_two(localNum = instruction->get_index());
696 break;
697
698 case Bytecodes::_lstore_0:
699 case Bytecodes::_dstore_0:
700 store_two(0);
701 break;
702
703 case Bytecodes::_lstore_1:
704 case Bytecodes::_dstore_1:
705 store_two(1);
706 break;
707
708 case Bytecodes::_lstore_2:
709 case Bytecodes::_dstore_2:
710 store_two(2);
711 break;
712
713 case Bytecodes::_lstore_3:
714 case Bytecodes::_dstore_3:
715 store_two(3);
716 break;
717
718 case Bytecodes::_istore:
719 case Bytecodes::_fstore:
720 case Bytecodes::_astore:
721 store_one(instruction->get_index());
722 break;
723
724 case Bytecodes::_istore_0:
725 case Bytecodes::_fstore_0:
726 case Bytecodes::_astore_0:
727 store_one(0);
728 break;
729
730 case Bytecodes::_istore_1:
731 case Bytecodes::_fstore_1:
732 case Bytecodes::_astore_1:
733 store_one(1);
734 break;
735
736 case Bytecodes::_istore_2:
737 case Bytecodes::_fstore_2:
738 case Bytecodes::_astore_2:
739 store_one(2);
740 break;
741
742 case Bytecodes::_istore_3:
743 case Bytecodes::_fstore_3:
744 case Bytecodes::_astore_3:
745 store_one(3);
746 break;
747
748 case Bytecodes::_wide:
749 fatal("Iterator should skip this bytecode");
750 break;
751
752 default:
753 tty->print("unexpected opcode: %d\n", instruction->cur_bc());
754 ShouldNotReachHere();
755 break;
756 }
757 }
758
759 void MethodLiveness::BasicBlock::load_two(int local) {
760 load_one(local);
761 load_one(local+1);
762 }
763
764 void MethodLiveness::BasicBlock::load_one(int local) {
765 if (!_kill.at(local)) {
766 _gen.at_put(local, true);
767 }
768 }
769
770 void MethodLiveness::BasicBlock::store_two(int local) {
771 store_one(local);
772 store_one(local+1);
773 }
774
775 void MethodLiveness::BasicBlock::store_one(int local) {
776 if (!_gen.at(local)) {
777 _kill.at_put(local, true);
778 }
779 }
780
781 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) {
782 // These set operations could be combined for efficiency if the
783 // performance of this analysis becomes an issue.
784 _entry.set_union(_normal_exit);
785 _entry.set_difference(_kill);
786 _entry.set_union(_gen);
787
788 // Note that we merge information from our exceptional successors
789 // just once, rather than at individual bytecodes.
790 _entry.set_union(_exception_exit);
791
792 if (TraceLivenessGen) {
793 tty->print_cr(" ** Visiting block at %d **", start_bci());
794 print_on(tty);
795 }
796
797 int i;
798 for (i=_normal_predecessors->length()-1; i>=0; i--) {
799 BasicBlock *block = _normal_predecessors->at(i);
800 if (block->merge_normal(_entry)) {
801 ml->work_list_add(block);
802 }
803 }
804 for (i=_exception_predecessors->length()-1; i>=0; i--) {
805 BasicBlock *block = _exception_predecessors->at(i);
806 if (block->merge_exception(_entry)) {
807 ml->work_list_add(block);
808 }
809 }
810 }
811
812 bool MethodLiveness::BasicBlock::merge_normal(const BitMap& other) {
813 return _normal_exit.set_union_with_result(other);
814 }
815
816 bool MethodLiveness::BasicBlock::merge_exception(const BitMap& other) {
817 return _exception_exit.set_union_with_result(other);
818 }
819
820 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) {
821 MethodLivenessResult answer(_analyzer->bit_map_size_bits());
822 answer.set_is_valid();
823
824 #ifndef ASSERT
825 if (bci == start_bci()) {
826 answer.set_from(_entry);
827 return answer;
828 }
829 #endif
830
831 #ifdef ASSERT
832 ResourceMark rm;
833 ResourceBitMap g(_gen.size()); g.set_from(_gen);
834 ResourceBitMap k(_kill.size()); k.set_from(_kill);
835 #endif
836 if (_last_bci != bci || trueInDebug) {
837 ciBytecodeStream bytes(method);
838 bytes.reset_to_bci(bci);
839 bytes.set_max_bci(limit_bci());
840 compute_gen_kill_range(&bytes);
841 assert(_last_bci != bci ||
842 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect");
843 _last_bci = bci;
844 }
845
846 answer.set_union(_normal_exit);
847 answer.set_difference(_kill);
848 answer.set_union(_gen);
849 answer.set_union(_exception_exit);
850
851 #ifdef ASSERT
852 if (bci == start_bci()) {
853 assert(answer.is_same(_entry), "optimized answer must be accurate");
854 }
855 #endif
856
857 return answer;
858 }
859
860 #ifndef PRODUCT
861
862 void MethodLiveness::BasicBlock::print_on(outputStream *os) const {
863 os->print_cr("===================================================================");
864 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci);
865 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length());
866 int i;
867 for (i=0; i < _normal_predecessors->length(); i++) {
868 os->print(" %4d", _normal_predecessors->at(i)->start_bci());
869 }
870 os->cr();
871 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length());
872 for (i=0; i < _exception_predecessors->length(); i++) {
873 os->print(" %4d", _exception_predecessors->at(i)->start_bci());
874 }
875 os->cr();
876 os->print (" Normal Exit : ");
877 _normal_exit.print_on(os);
878 os->print (" Gen : ");
879 _gen.print_on(os);
880 os->print (" Kill : ");
881 _kill.print_on(os);
882 os->print (" Exception Exit: ");
883 _exception_exit.print_on(os);
884 os->print (" Entry : ");
885 _entry.print_on(os);
886 }
887
888 #endif // PRODUCT