1 /*
2 * Copyright (c) 1998, 2021, 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 "classfile/vmIntrinsics.hpp"
30 #include "compiler/methodLiveness.hpp"
31 #include "interpreter/bytecode.hpp"
32 #include "interpreter/bytecodes.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/resourceArea.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 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method)
75 #ifdef COMPILER1
76 : _bci_block_start(arena, method->code_size())
77 #endif
78 {
79 _arena = arena;
80 _method = method;
81 _bit_map_size_bits = method->max_locals();
82 }
83
84 void MethodLiveness::compute_liveness() {
85 #ifndef PRODUCT
86 if (TraceLivenessGen) {
87 tty->print_cr("################################################################");
88 tty->print("# Computing liveness information for ");
89 method()->print_short_name();
90 }
91 #endif
92
93 init_basic_blocks();
94 init_gen_kill();
95 propagate_liveness();
96 }
97
98
99 void MethodLiveness::init_basic_blocks() {
100 int method_len = method()->code_size();
101 ciMethodBlocks *mblocks = method()->get_method_blocks();
102
103 // Create an array to store the bci->BasicBlock mapping.
104 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL);
105
106 _block_count = mblocks->num_blocks();
107 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count);
108
109 // Used for patching up jsr/ret control flow.
110 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5);
111 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5);
112
113 // generate our block list from ciMethodBlocks
114 for (int blk = 0; blk < _block_count; blk++) {
115 ciBlock *cib = mblocks->block(blk);
116 int start_bci = cib->start_bci();
117 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci());
118 _block_map->at_put(start_bci, _block_list[blk]);
119 #ifdef COMPILER1
120 // mark all bcis where a new basic block starts
121 _bci_block_start.set_bit(start_bci);
122 #endif // COMPILER1
123 }
124 // fill in the predecessors of blocks
125 ciBytecodeStream bytes(method());
126
127 for (int blk = 0; blk < _block_count; blk++) {
128 BasicBlock *current_block = _block_list[blk];
129 int bci = mblocks->block(blk)->control_bci();
130
131 if (bci == ciBlock::fall_through_bci) {
132 int limit = current_block->limit_bci();
133 if (limit < method_len) {
134 BasicBlock *next = _block_map->at(limit);
135 assert( next != NULL, "must be a block immediately following this one.");
136 next->add_normal_predecessor(current_block);
137 }
138 continue;
139 }
140 bytes.reset_to_bci(bci);
141 Bytecodes::Code code = bytes.next();
142 BasicBlock *dest;
143
144 // Now we need to interpret the instruction's effect
145 // on control flow.
146 assert (current_block != NULL, "we must have a current block");
147 switch (code) {
148 case Bytecodes::_ifeq:
149 case Bytecodes::_ifne:
150 case Bytecodes::_iflt:
151 case Bytecodes::_ifge:
152 case Bytecodes::_ifgt:
153 case Bytecodes::_ifle:
154 case Bytecodes::_if_icmpeq:
155 case Bytecodes::_if_icmpne:
156 case Bytecodes::_if_icmplt:
157 case Bytecodes::_if_icmpge:
158 case Bytecodes::_if_icmpgt:
159 case Bytecodes::_if_icmple:
160 case Bytecodes::_if_acmpeq:
161 case Bytecodes::_if_acmpne:
162 case Bytecodes::_ifnull:
163 case Bytecodes::_ifnonnull:
164 // Two way branch. Set predecessors at each destination.
165 dest = _block_map->at(bytes.next_bci());
166 assert(dest != NULL, "must be a block immediately following this one.");
167 dest->add_normal_predecessor(current_block);
168
169 dest = _block_map->at(bytes.get_dest());
170 assert(dest != NULL, "branch desination must start a block.");
171 dest->add_normal_predecessor(current_block);
172 break;
173 case Bytecodes::_goto:
174 dest = _block_map->at(bytes.get_dest());
175 assert(dest != NULL, "branch desination must start a block.");
176 dest->add_normal_predecessor(current_block);
177 break;
178 case Bytecodes::_goto_w:
179 dest = _block_map->at(bytes.get_far_dest());
180 assert(dest != NULL, "branch desination must start a block.");
181 dest->add_normal_predecessor(current_block);
182 break;
183 case Bytecodes::_tableswitch:
184 {
185 Bytecode_tableswitch tableswitch(&bytes);
186
187 int len = tableswitch.length();
188
189 dest = _block_map->at(bci + tableswitch.default_offset());
190 assert(dest != NULL, "branch desination must start a block.");
191 dest->add_normal_predecessor(current_block);
192 while (--len >= 0) {
193 dest = _block_map->at(bci + tableswitch.dest_offset_at(len));
194 assert(dest != NULL, "branch desination must start a block.");
195 dest->add_normal_predecessor(current_block);
196 }
197 break;
198 }
199
200 case Bytecodes::_lookupswitch:
201 {
202 Bytecode_lookupswitch lookupswitch(&bytes);
203
204 int npairs = lookupswitch.number_of_pairs();
205
206 dest = _block_map->at(bci + lookupswitch.default_offset());
207 assert(dest != NULL, "branch desination must start a block.");
208 dest->add_normal_predecessor(current_block);
209 while(--npairs >= 0) {
210 LookupswitchPair pair = lookupswitch.pair_at(npairs);
211 dest = _block_map->at( bci + pair.offset());
212 assert(dest != NULL, "branch desination must start a block.");
213 dest->add_normal_predecessor(current_block);
214 }
215 break;
216 }
217
218 case Bytecodes::_jsr:
219 {
220 assert(bytes.is_wide()==false, "sanity check");
221 dest = _block_map->at(bytes.get_dest());
222 assert(dest != NULL, "branch desination must start a block.");
223 dest->add_normal_predecessor(current_block);
224 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
225 assert(jsrExit != NULL, "jsr return bci must start a block.");
226 jsr_exit_list->append(jsrExit);
227 break;
228 }
229 case Bytecodes::_jsr_w:
230 {
231 dest = _block_map->at(bytes.get_far_dest());
232 assert(dest != NULL, "branch desination must start a block.");
233 dest->add_normal_predecessor(current_block);
234 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
235 assert(jsrExit != NULL, "jsr return bci must start a block.");
236 jsr_exit_list->append(jsrExit);
237 break;
238 }
239
240 case Bytecodes::_wide:
241 assert(false, "wide opcodes should not be seen here");
242 break;
243 case Bytecodes::_athrow:
244 case Bytecodes::_ireturn:
245 case Bytecodes::_lreturn:
246 case Bytecodes::_freturn:
247 case Bytecodes::_dreturn:
248 case Bytecodes::_areturn:
249 case Bytecodes::_return:
250 // These opcodes are not the normal predecessors of any other opcodes.
251 break;
252 case Bytecodes::_ret:
253 // We will patch up jsr/rets in a subsequent pass.
254 ret_list->append(current_block);
255 break;
256 default:
257 // Do nothing.
258 break;
259 }
260 }
261 // Patch up the jsr/ret's. We conservatively assume that any ret
262 // can return to any jsr site.
263 int ret_list_len = ret_list->length();
264 int jsr_exit_list_len = jsr_exit_list->length();
265 if (ret_list_len > 0 && jsr_exit_list_len > 0) {
266 for (int i = jsr_exit_list_len - 1; i >= 0; i--) {
267 BasicBlock *jsrExit = jsr_exit_list->at(i);
268 for (int i = ret_list_len - 1; i >= 0; i--) {
269 jsrExit->add_normal_predecessor(ret_list->at(i));
270 }
271 }
272 }
273
274 // Compute exception edges.
275 for (int b=_block_count-1; b >= 0; b--) {
276 BasicBlock *block = _block_list[b];
277 int block_start = block->start_bci();
278 int block_limit = block->limit_bci();
279 ciExceptionHandlerStream handlers(method());
280 for (; !handlers.is_done(); handlers.next()) {
281 ciExceptionHandler* handler = handlers.handler();
282 int start = handler->start();
283 int limit = handler->limit();
284 int handler_bci = handler->handler_bci();
285
286 int intersect_start = MAX2(block_start, start);
287 int intersect_limit = MIN2(block_limit, limit);
288 if (intersect_start < intersect_limit) {
289 // The catch range has a nonempty intersection with this
290 // basic block. That means this basic block can be an
291 // exceptional predecessor.
292 _block_map->at(handler_bci)->add_exception_predecessor(block);
293
294 if (handler->is_catch_all()) {
295 // This is a catch-all block.
296 if (intersect_start == block_start && intersect_limit == block_limit) {
297 // The basic block is entirely contained in this catch-all block.
298 // Skip the rest of the exception handlers -- they can never be
299 // reached in execution.
300 break;
301 }
302 }
303 }
304 }
305 }
306 }
307
308 void MethodLiveness::init_gen_kill() {
309 for (int i=_block_count-1; i >= 0; i--) {
310 _block_list[i]->compute_gen_kill(method());
311 }
312 }
313
314 void MethodLiveness::propagate_liveness() {
315 int num_blocks = _block_count;
316 BasicBlock *block;
317
318 // We start our work list off with all blocks in it.
319 // Alternately, we could start off the work list with the list of all
320 // blocks which could exit the method directly, along with one block
321 // from any infinite loop. If this matters, it can be changed. It
322 // may not be clear from looking at the code, but the order of the
323 // workList will be the opposite of the creation order of the basic
324 // blocks, which should be decent for quick convergence (with the
325 // possible exception of exception handlers, which are all created
326 // early).
327 _work_list = NULL;
328 for (int i = 0; i < num_blocks; i++) {
329 block = _block_list[i];
330 block->set_next(_work_list);
331 block->set_on_work_list(true);
332 _work_list = block;
333 }
334
335
336 while ((block = work_list_get()) != NULL) {
337 block->propagate(this);
338 }
339 }
340
341 void MethodLiveness::work_list_add(BasicBlock *block) {
342 if (!block->on_work_list()) {
343 block->set_next(_work_list);
344 block->set_on_work_list(true);
345 _work_list = block;
346 }
347 }
348
349 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() {
350 BasicBlock *block = _work_list;
351 if (block != NULL) {
352 block->set_on_work_list(false);
353 _work_list = block->next();
354 }
355 return block;
356 }
357
358
359 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) {
360 int bci = entry_bci;
361 bool is_entry = false;
362 if (entry_bci == InvocationEntryBci) {
363 is_entry = true;
364 bci = 0;
365 }
366
367 MethodLivenessResult answer;
368
369 if (_block_count > 0) {
370
371 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" );
372 BasicBlock *block = _block_map->at(bci);
373 // We may not be at the block start, so search backwards to find the block
374 // containing bci.
375 int t = bci;
376 while (block == NULL && t > 0) {
377 block = _block_map->at(--t);
378 }
379 guarantee(block != NULL, "invalid bytecode index; must be instruction index");
380 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci.");
381
382 answer = block->get_liveness_at(method(), bci);
383
384 if (is_entry && method()->is_synchronized() && !method()->is_static()) {
385 // Synchronized methods use the receiver once on entry.
386 answer.at_put(0, true);
387 }
388
389 #ifndef PRODUCT
390 if (TraceLivenessQuery) {
391 tty->print("Liveness query of ");
392 method()->print_short_name();
393 tty->print(" @ %d : result is ", bci);
394 answer.print_on(tty);
395 }
396 #endif
397 }
398
399 return answer;
400 }
401
402 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) :
403 _entry(analyzer->arena(), analyzer->bit_map_size_bits()),
404 _normal_exit(analyzer->arena(), analyzer->bit_map_size_bits()),
405 _exception_exit(analyzer->arena(), analyzer->bit_map_size_bits()),
406 _gen(analyzer->arena(), analyzer->bit_map_size_bits()),
407 _kill(analyzer->arena(), analyzer->bit_map_size_bits()),
408 _last_bci(-1) {
409 _analyzer = analyzer;
410 _start_bci = start;
411 _limit_bci = limit;
412 _normal_predecessors =
413 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
414 _exception_predecessors =
415 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
416 }
417
418
419
420 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) {
421 int start = _start_bci;
422 int limit = _limit_bci;
423
424 if (TraceLivenessGen) {
425 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci);
426 }
427
428 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors;
429
430 assert (start < split_bci && split_bci < limit, "improper split");
431
432 // Make a new block to cover the first half of the range.
433 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci);
434
435 // Assign correct values to the second half (this)
436 _normal_predecessors = first_half->_normal_predecessors;
437 _start_bci = split_bci;
438 add_normal_predecessor(first_half);
439
440 // Assign correct predecessors to the new first half
441 first_half->_normal_predecessors = save_predecessors;
442
443 return first_half;
444 }
445
446 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) {
447 ciBytecodeStream bytes(method);
448 bytes.reset_to_bci(start_bci());
449 bytes.set_max_bci(limit_bci());
450 compute_gen_kill_range(&bytes);
451
452 }
453
454 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) {
455 _gen.clear();
456 _kill.clear();
457
458 while (bytes->next() != ciBytecodeStream::EOBC()) {
459 compute_gen_kill_single(bytes);
460 }
461 }
462
463 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) {
464 // We prohibit _gen and _kill from having locals in common. If we
465 // know that one is definitely going to be applied before the other,
466 // we could save some computation time by relaxing this prohibition.
467
468 switch (instruction->cur_bc()) {
469 case Bytecodes::_nop:
470 case Bytecodes::_goto:
471 case Bytecodes::_goto_w:
472 case Bytecodes::_aconst_null:
473 case Bytecodes::_new:
474 case Bytecodes::_aconst_init:475 case Bytecodes::_withfield:
476 case Bytecodes::_iconst_m1:
477 case Bytecodes::_iconst_0:
478 case Bytecodes::_iconst_1:
479 case Bytecodes::_iconst_2:
480 case Bytecodes::_iconst_3:
481 case Bytecodes::_iconst_4:
482 case Bytecodes::_iconst_5:
483 case Bytecodes::_fconst_0:
484 case Bytecodes::_fconst_1:
485 case Bytecodes::_fconst_2:
486 case Bytecodes::_bipush:
487 case Bytecodes::_sipush:
488 case Bytecodes::_lconst_0:
489 case Bytecodes::_lconst_1:
490 case Bytecodes::_dconst_0:
491 case Bytecodes::_dconst_1:
492 case Bytecodes::_ldc2_w:
493 case Bytecodes::_ldc:
494 case Bytecodes::_ldc_w:
495 case Bytecodes::_iaload:
496 case Bytecodes::_faload:
497 case Bytecodes::_baload:
498 case Bytecodes::_caload:
499 case Bytecodes::_saload:
500 case Bytecodes::_laload:
501 case Bytecodes::_daload:
502 case Bytecodes::_aaload:
503 case Bytecodes::_iastore:
504 case Bytecodes::_fastore:
505 case Bytecodes::_bastore:
506 case Bytecodes::_castore:
507 case Bytecodes::_sastore:
508 case Bytecodes::_lastore:
509 case Bytecodes::_dastore:
510 case Bytecodes::_aastore:
511 case Bytecodes::_pop:
512 case Bytecodes::_pop2:
513 case Bytecodes::_dup:
514 case Bytecodes::_dup_x1:
515 case Bytecodes::_dup_x2:
516 case Bytecodes::_dup2:
517 case Bytecodes::_dup2_x1:
518 case Bytecodes::_dup2_x2:
519 case Bytecodes::_swap:
520 case Bytecodes::_iadd:
521 case Bytecodes::_fadd:
522 case Bytecodes::_isub:
523 case Bytecodes::_fsub:
524 case Bytecodes::_imul:
525 case Bytecodes::_fmul:
526 case Bytecodes::_idiv:
527 case Bytecodes::_fdiv:
528 case Bytecodes::_irem:
529 case Bytecodes::_frem:
530 case Bytecodes::_ishl:
531 case Bytecodes::_ishr:
532 case Bytecodes::_iushr:
533 case Bytecodes::_iand:
534 case Bytecodes::_ior:
535 case Bytecodes::_ixor:
536 case Bytecodes::_l2f:
537 case Bytecodes::_l2i:
538 case Bytecodes::_d2f:
539 case Bytecodes::_d2i:
540 case Bytecodes::_fcmpl:
541 case Bytecodes::_fcmpg:
542 case Bytecodes::_ladd:
543 case Bytecodes::_dadd:
544 case Bytecodes::_lsub:
545 case Bytecodes::_dsub:
546 case Bytecodes::_lmul:
547 case Bytecodes::_dmul:
548 case Bytecodes::_ldiv:
549 case Bytecodes::_ddiv:
550 case Bytecodes::_lrem:
551 case Bytecodes::_drem:
552 case Bytecodes::_land:
553 case Bytecodes::_lor:
554 case Bytecodes::_lxor:
555 case Bytecodes::_ineg:
556 case Bytecodes::_fneg:
557 case Bytecodes::_i2f:
558 case Bytecodes::_f2i:
559 case Bytecodes::_i2c:
560 case Bytecodes::_i2s:
561 case Bytecodes::_i2b:
562 case Bytecodes::_lneg:
563 case Bytecodes::_dneg:
564 case Bytecodes::_l2d:
565 case Bytecodes::_d2l:
566 case Bytecodes::_lshl:
567 case Bytecodes::_lshr:
568 case Bytecodes::_lushr:
569 case Bytecodes::_i2l:
570 case Bytecodes::_i2d:
571 case Bytecodes::_f2l:
572 case Bytecodes::_f2d:
573 case Bytecodes::_lcmp:
574 case Bytecodes::_dcmpl:
575 case Bytecodes::_dcmpg:
576 case Bytecodes::_ifeq:
577 case Bytecodes::_ifne:
578 case Bytecodes::_iflt:
579 case Bytecodes::_ifge:
580 case Bytecodes::_ifgt:
581 case Bytecodes::_ifle:
582 case Bytecodes::_tableswitch:
583 case Bytecodes::_ireturn:
584 case Bytecodes::_freturn:
585 case Bytecodes::_if_icmpeq:
586 case Bytecodes::_if_icmpne:
587 case Bytecodes::_if_icmplt:
588 case Bytecodes::_if_icmpge:
589 case Bytecodes::_if_icmpgt:
590 case Bytecodes::_if_icmple:
591 case Bytecodes::_lreturn:
592 case Bytecodes::_dreturn:
593 case Bytecodes::_if_acmpeq:
594 case Bytecodes::_if_acmpne:
595 case Bytecodes::_jsr:
596 case Bytecodes::_jsr_w:
597 case Bytecodes::_getstatic:
598 case Bytecodes::_putstatic:
599 case Bytecodes::_getfield:
600 case Bytecodes::_putfield:
601 case Bytecodes::_invokevirtual:
602 case Bytecodes::_invokespecial:
603 case Bytecodes::_invokestatic:
604 case Bytecodes::_invokeinterface:
605 case Bytecodes::_invokedynamic:
606 case Bytecodes::_newarray:
607 case Bytecodes::_anewarray:
608 case Bytecodes::_checkcast:
609 case Bytecodes::_arraylength:
610 case Bytecodes::_instanceof:
611 case Bytecodes::_athrow:
612 case Bytecodes::_areturn:
613 case Bytecodes::_monitorenter:
614 case Bytecodes::_monitorexit:
615 case Bytecodes::_ifnull:
616 case Bytecodes::_ifnonnull:
617 case Bytecodes::_multianewarray:
618 case Bytecodes::_lookupswitch:
619 // These bytecodes have no effect on the method's locals.
620 break;
621
622 case Bytecodes::_return:
623 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) {
624 // return from Object.init implicitly registers a finalizer
625 // for the receiver if needed, so keep it alive.
626 load_one(0);
627 }
628 break;
629
630
631 case Bytecodes::_lload:
632 case Bytecodes::_dload:
633 load_two(instruction->get_index());
634 break;
635
636 case Bytecodes::_lload_0:
637 case Bytecodes::_dload_0:
638 load_two(0);
639 break;
640
641 case Bytecodes::_lload_1:
642 case Bytecodes::_dload_1:
643 load_two(1);
644 break;
645
646 case Bytecodes::_lload_2:
647 case Bytecodes::_dload_2:
648 load_two(2);
649 break;
650
651 case Bytecodes::_lload_3:
652 case Bytecodes::_dload_3:
653 load_two(3);
654 break;
655
656 case Bytecodes::_iload:
657 case Bytecodes::_iinc:
658 case Bytecodes::_fload:
659 case Bytecodes::_aload:
660 case Bytecodes::_ret:
661 load_one(instruction->get_index());
662 break;
663
664 case Bytecodes::_iload_0:
665 case Bytecodes::_fload_0:
666 case Bytecodes::_aload_0:
667 load_one(0);
668 break;
669
670 case Bytecodes::_iload_1:
671 case Bytecodes::_fload_1:
672 case Bytecodes::_aload_1:
673 load_one(1);
674 break;
675
676 case Bytecodes::_iload_2:
677 case Bytecodes::_fload_2:
678 case Bytecodes::_aload_2:
679 load_one(2);
680 break;
681
682 case Bytecodes::_iload_3:
683 case Bytecodes::_fload_3:
684 case Bytecodes::_aload_3:
685 load_one(3);
686 break;
687
688 case Bytecodes::_lstore:
689 case Bytecodes::_dstore:
690 store_two(instruction->get_index());
691 break;
692
693 case Bytecodes::_lstore_0:
694 case Bytecodes::_dstore_0:
695 store_two(0);
696 break;
697
698 case Bytecodes::_lstore_1:
699 case Bytecodes::_dstore_1:
700 store_two(1);
701 break;
702
703 case Bytecodes::_lstore_2:
704 case Bytecodes::_dstore_2:
705 store_two(2);
706 break;
707
708 case Bytecodes::_lstore_3:
709 case Bytecodes::_dstore_3:
710 store_two(3);
711 break;
712
713 case Bytecodes::_istore:
714 case Bytecodes::_fstore:
715 case Bytecodes::_astore:
716 store_one(instruction->get_index());
717 break;
718
719 case Bytecodes::_istore_0:
720 case Bytecodes::_fstore_0:
721 case Bytecodes::_astore_0:
722 store_one(0);
723 break;
724
725 case Bytecodes::_istore_1:
726 case Bytecodes::_fstore_1:
727 case Bytecodes::_astore_1:
728 store_one(1);
729 break;
730
731 case Bytecodes::_istore_2:
732 case Bytecodes::_fstore_2:
733 case Bytecodes::_astore_2:
734 store_one(2);
735 break;
736
737 case Bytecodes::_istore_3:
738 case Bytecodes::_fstore_3:
739 case Bytecodes::_astore_3:
740 store_one(3);
741 break;
742
743 case Bytecodes::_wide:
744 fatal("Iterator should skip this bytecode");
745 break;
746
747 default:
748 tty->print("unexpected opcode: %d\n", instruction->cur_bc());
749 ShouldNotReachHere();
750 break;
751 }
752 }
753
754 void MethodLiveness::BasicBlock::load_two(int local) {
755 load_one(local);
756 load_one(local+1);
757 }
758
759 void MethodLiveness::BasicBlock::load_one(int local) {
760 if (!_kill.at(local)) {
761 _gen.at_put(local, true);
762 }
763 }
764
765 void MethodLiveness::BasicBlock::store_two(int local) {
766 store_one(local);
767 store_one(local+1);
768 }
769
770 void MethodLiveness::BasicBlock::store_one(int local) {
771 if (!_gen.at(local)) {
772 _kill.at_put(local, true);
773 }
774 }
775
776 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) {
777 // These set operations could be combined for efficiency if the
778 // performance of this analysis becomes an issue.
779 _entry.set_union(_normal_exit);
780 _entry.set_difference(_kill);
781 _entry.set_union(_gen);
782
783 // Note that we merge information from our exceptional successors
784 // just once, rather than at individual bytecodes.
785 _entry.set_union(_exception_exit);
786
787 if (TraceLivenessGen) {
788 tty->print_cr(" ** Visiting block at %d **", start_bci());
789 print_on(tty);
790 }
791
792 int i;
793 for (i=_normal_predecessors->length()-1; i>=0; i--) {
794 BasicBlock *block = _normal_predecessors->at(i);
795 if (block->merge_normal(_entry)) {
796 ml->work_list_add(block);
797 }
798 }
799 for (i=_exception_predecessors->length()-1; i>=0; i--) {
800 BasicBlock *block = _exception_predecessors->at(i);
801 if (block->merge_exception(_entry)) {
802 ml->work_list_add(block);
803 }
804 }
805 }
806
807 bool MethodLiveness::BasicBlock::merge_normal(const BitMap& other) {
808 return _normal_exit.set_union_with_result(other);
809 }
810
811 bool MethodLiveness::BasicBlock::merge_exception(const BitMap& other) {
812 return _exception_exit.set_union_with_result(other);
813 }
814
815 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) {
816 MethodLivenessResult answer(_analyzer->bit_map_size_bits());
817 answer.set_is_valid();
818
819 #ifndef ASSERT
820 if (bci == start_bci()) {
821 answer.set_from(_entry);
822 return answer;
823 }
824 #endif
825
826 #ifdef ASSERT
827 ResourceMark rm;
828 ResourceBitMap g(_gen.size(), false); g.set_from(_gen);
829 ResourceBitMap k(_kill.size(), false); k.set_from(_kill);
830 #endif
831 if (_last_bci != bci || trueInDebug) {
832 ciBytecodeStream bytes(method);
833 bytes.reset_to_bci(bci);
834 bytes.set_max_bci(limit_bci());
835 compute_gen_kill_range(&bytes);
836 assert(_last_bci != bci ||
837 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect");
838 _last_bci = bci;
839 }
840
841 answer.set_union(_normal_exit);
842 answer.set_difference(_kill);
843 answer.set_union(_gen);
844 answer.set_union(_exception_exit);
845
846 #ifdef ASSERT
847 if (bci == start_bci()) {
848 assert(answer.is_same(_entry), "optimized answer must be accurate");
849 }
850 #endif
851
852 return answer;
853 }
854
855 #ifndef PRODUCT
856
857 void MethodLiveness::BasicBlock::print_on(outputStream *os) const {
858 os->print_cr("===================================================================");
859 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci);
860 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length());
861 int i;
862 for (i=0; i < _normal_predecessors->length(); i++) {
863 os->print(" %4d", _normal_predecessors->at(i)->start_bci());
864 }
865 os->cr();
866 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length());
867 for (i=0; i < _exception_predecessors->length(); i++) {
868 os->print(" %4d", _exception_predecessors->at(i)->start_bci());
869 }
870 os->cr();
871 os->print (" Normal Exit : ");
872 _normal_exit.print_on(os);
873 os->print (" Gen : ");
874 _gen.print_on(os);
875 os->print (" Kill : ");
876 _kill.print_on(os);
877 os->print (" Exception Exit: ");
878 _exception_exit.print_on(os);
879 os->print (" Entry : ");
880 _entry.print_on(os);
881 }
882
883 #endif // PRODUCT
--- EOF ---