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::_vreturn: 351 case Bytecodes::_return: 352 // These opcodes are not the normal predecessors of any other opcodes. 353 break; 354 case Bytecodes::_ret: 355 // We will patch up jsr/rets in a subsequent pass. 356 ret_list->append(current_block); 357 break; 358 case Bytecodes::_breakpoint: 359 // Bail out of there are breakpoints in here. 360 bailout = true; 361 break; 362 default: 363 // Do nothing. 364 break; 365 } 366 } 367 // Patch up the jsr/ret's. We conservatively assume that any ret 368 // can return to any jsr site. 369 int ret_list_len = ret_list->length(); 370 int jsr_exit_list_len = jsr_exit_list->length(); 371 if (ret_list_len > 0 && jsr_exit_list_len > 0) { 372 for (int i = jsr_exit_list_len - 1; i >= 0; i--) { 373 BasicBlock *jsrExit = jsr_exit_list->at(i); 374 for (int i = ret_list_len - 1; i >= 0; i--) { 375 jsrExit->add_normal_predecessor(ret_list->at(i)); 376 } 377 } 378 } 379 380 // Compute exception edges. 381 for (int b=_block_count-1; b >= 0; b--) { 382 BasicBlock *block = _block_list[b]; 383 int block_start = block->start_bci(); 384 int block_limit = block->limit_bci(); 385 ciExceptionHandlerStream handlers(method()); 386 for (; !handlers.is_done(); handlers.next()) { 387 ciExceptionHandler* handler = handlers.handler(); 388 int start = handler->start(); 389 int limit = handler->limit(); 390 int handler_bci = handler->handler_bci(); 391 392 int intersect_start = MAX2(block_start, start); 393 int intersect_limit = MIN2(block_limit, limit); 394 if (intersect_start < intersect_limit) { 395 // The catch range has a nonempty intersection with this 396 // basic block. That means this basic block can be an 397 // exceptional predecessor. 398 _block_map->at(handler_bci)->add_exception_predecessor(block); 399 400 if (handler->is_catch_all()) { 401 // This is a catch-all block. 402 if (intersect_start == block_start && intersect_limit == block_limit) { 403 // The basic block is entirely contained in this catch-all block. 404 // Skip the rest of the exception handlers -- they can never be 405 // reached in execution. 406 break; 407 } 408 } 409 } 410 } 411 } 412 } 413 414 void MethodLiveness::init_gen_kill() { 415 for (int i=_block_count-1; i >= 0; i--) { 416 _block_list[i]->compute_gen_kill(method()); 417 } 418 } 419 420 void MethodLiveness::propagate_liveness() { 421 int num_blocks = _block_count; 422 BasicBlock *block; 423 424 // We start our work list off with all blocks in it. 425 // Alternately, we could start off the work list with the list of all 426 // blocks which could exit the method directly, along with one block 427 // from any infinite loop. If this matters, it can be changed. It 428 // may not be clear from looking at the code, but the order of the 429 // workList will be the opposite of the creation order of the basic 430 // blocks, which should be decent for quick convergence (with the 431 // possible exception of exception handlers, which are all created 432 // early). 433 _work_list = NULL; 434 for (int i = 0; i < num_blocks; i++) { 435 block = _block_list[i]; 436 block->set_next(_work_list); 437 block->set_on_work_list(true); 438 _work_list = block; 439 } 440 441 442 while ((block = work_list_get()) != NULL) { 443 block->propagate(this); 444 NOT_PRODUCT(_total_visits++;) 445 } 446 } 447 448 void MethodLiveness::work_list_add(BasicBlock *block) { 449 if (!block->on_work_list()) { 450 block->set_next(_work_list); 451 block->set_on_work_list(true); 452 _work_list = block; 453 } 454 } 455 456 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() { 457 BasicBlock *block = _work_list; 458 if (block != NULL) { 459 block->set_on_work_list(false); 460 _work_list = block->next(); 461 } 462 return block; 463 } 464 465 466 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) { 467 int bci = entry_bci; 468 bool is_entry = false; 469 if (entry_bci == InvocationEntryBci) { 470 is_entry = true; 471 bci = 0; 472 } 473 474 MethodLivenessResult answer; 475 476 if (_block_count > 0) { 477 if (TimeLivenessAnalysis) _time_total.start(); 478 if (TimeLivenessAnalysis) _time_query.start(); 479 480 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" ); 481 BasicBlock *block = _block_map->at(bci); 482 // We may not be at the block start, so search backwards to find the block 483 // containing bci. 484 int t = bci; 485 while (block == NULL && t > 0) { 486 block = _block_map->at(--t); 487 } 488 assert( block != NULL, "invalid bytecode index; must be instruction index" ); 489 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci."); 490 491 answer = block->get_liveness_at(method(), bci); 492 493 if (is_entry && method()->is_synchronized() && !method()->is_static()) { 494 // Synchronized methods use the receiver once on entry. 495 answer.at_put(0, true); 496 } 497 498 #ifndef PRODUCT 499 if (TraceLivenessQuery) { 500 tty->print("Liveness query of "); 501 method()->print_short_name(); 502 tty->print(" @ %d : result is ", bci); 503 answer.print_on(tty); 504 } 505 506 if (TimeLivenessAnalysis) _time_query.stop(); 507 if (TimeLivenessAnalysis) _time_total.stop(); 508 #endif 509 } 510 511 #ifndef PRODUCT 512 if (TimeLivenessAnalysis) { 513 // Collect statistics. 514 _total_locals_queried += _bit_map_size_bits; 515 BitCounter counter; 516 answer.iterate(&counter); 517 _total_live_locals_queried += counter.count(); 518 } 519 #endif 520 521 return answer; 522 } 523 524 525 #ifndef PRODUCT 526 527 void MethodLiveness::print_times() { 528 tty->print_cr ("Accumulated liveness analysis times/statistics:"); 529 tty->print_cr ("-----------------------------------------------"); 530 tty->print_cr (" Total : %3.3f sec.", _time_total.seconds()); 531 tty->print_cr (" Build graph : %3.3f sec. (%2.2f%%)", _time_build_graph.seconds(), 532 _time_build_graph.seconds() * 100 / _time_total.seconds()); 533 tty->print_cr (" Gen / Kill : %3.3f sec. (%2.2f%%)", _time_gen_kill.seconds(), 534 _time_gen_kill.seconds() * 100 / _time_total.seconds()); 535 tty->print_cr (" Dataflow : %3.3f sec. (%2.2f%%)", _time_flow.seconds(), 536 _time_flow.seconds() * 100 / _time_total.seconds()); 537 tty->print_cr (" Query : %3.3f sec. (%2.2f%%)", _time_query.seconds(), 538 _time_query.seconds() * 100 / _time_total.seconds()); 539 tty->print_cr (" #bytes : %8ld (%3.0f bytes per sec)", 540 _total_bytes, 541 _total_bytes / _time_total.seconds()); 542 tty->print_cr (" #methods : %8d (%3.0f methods per sec)", 543 _total_methods, 544 _total_methods / _time_total.seconds()); 545 tty->print_cr (" avg locals : %3.3f max locals : %3d", 546 (float)_total_method_locals / _total_methods, 547 _max_method_locals); 548 tty->print_cr (" avg blocks : %3.3f max blocks : %3d", 549 (float)_total_blocks / _total_methods, 550 _max_method_blocks); 551 tty->print_cr (" avg bytes : %3.3f", 552 (float)_total_bytes / _total_methods); 553 tty->print_cr (" #blocks : %8ld", 554 _total_blocks); 555 tty->print_cr (" avg normal predecessors : %3.3f max normal predecessors : %3d", 556 (float)_total_edges / _total_blocks, 557 _max_block_edges); 558 tty->print_cr (" avg exception predecessors : %3.3f max exception predecessors : %3d", 559 (float)_total_exc_edges / _total_blocks, 560 _max_block_exc_edges); 561 tty->print_cr (" avg visits : %3.3f", 562 (float)_total_visits / _total_blocks); 563 tty->print_cr (" #locals queried : %8ld #live : %8ld %%live : %2.2f%%", 564 _total_locals_queried, 565 _total_live_locals_queried, 566 100.0 * _total_live_locals_queried / _total_locals_queried); 567 } 568 569 #endif 570 571 572 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) : 573 _gen(analyzer->arena(), analyzer->bit_map_size_bits()), 574 _kill(analyzer->arena(), analyzer->bit_map_size_bits()), 575 _entry(analyzer->arena(), analyzer->bit_map_size_bits()), 576 _normal_exit(analyzer->arena(), analyzer->bit_map_size_bits()), 577 _exception_exit(analyzer->arena(), analyzer->bit_map_size_bits()), 578 _last_bci(-1) { 579 _analyzer = analyzer; 580 _start_bci = start; 581 _limit_bci = limit; 582 _normal_predecessors = 583 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 584 _exception_predecessors = 585 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 586 } 587 588 589 590 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) { 591 int start = _start_bci; 592 int limit = _limit_bci; 593 594 if (TraceLivenessGen) { 595 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci); 596 } 597 598 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors; 599 600 assert (start < split_bci && split_bci < limit, "improper split"); 601 602 // Make a new block to cover the first half of the range. 603 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci); 604 605 // Assign correct values to the second half (this) 606 _normal_predecessors = first_half->_normal_predecessors; 607 _start_bci = split_bci; 608 add_normal_predecessor(first_half); 609 610 // Assign correct predecessors to the new first half 611 first_half->_normal_predecessors = save_predecessors; 612 613 return first_half; 614 } 615 616 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) { 617 ciBytecodeStream bytes(method); 618 bytes.reset_to_bci(start_bci()); 619 bytes.set_max_bci(limit_bci()); 620 compute_gen_kill_range(&bytes); 621 622 } 623 624 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) { 625 _gen.clear(); 626 _kill.clear(); 627 628 while (bytes->next() != ciBytecodeStream::EOBC()) { 629 compute_gen_kill_single(bytes); 630 } 631 } 632 633 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) { 634 int localNum; 635 636 // We prohibit _gen and _kill from having locals in common. If we 637 // know that one is definitely going to be applied before the other, 638 // we could save some computation time by relaxing this prohibition. 639 640 switch (instruction->cur_bc()) { 641 case Bytecodes::_nop: 642 case Bytecodes::_goto: 643 case Bytecodes::_goto_w: 644 case Bytecodes::_aconst_null: 645 case Bytecodes::_new: 646 case Bytecodes::_vdefault: 647 case Bytecodes::_vwithfield: 648 case Bytecodes::_iconst_m1: 649 case Bytecodes::_iconst_0: 650 case Bytecodes::_iconst_1: 651 case Bytecodes::_iconst_2: 652 case Bytecodes::_iconst_3: 653 case Bytecodes::_iconst_4: 654 case Bytecodes::_iconst_5: 655 case Bytecodes::_fconst_0: 656 case Bytecodes::_fconst_1: 657 case Bytecodes::_fconst_2: 658 case Bytecodes::_bipush: 659 case Bytecodes::_sipush: 660 case Bytecodes::_lconst_0: 661 case Bytecodes::_lconst_1: 662 case Bytecodes::_dconst_0: 663 case Bytecodes::_dconst_1: 664 case Bytecodes::_ldc2_w: 665 case Bytecodes::_ldc: 666 case Bytecodes::_ldc_w: 667 case Bytecodes::_iaload: 668 case Bytecodes::_faload: 669 case Bytecodes::_baload: 670 case Bytecodes::_caload: 671 case Bytecodes::_saload: 672 case Bytecodes::_laload: 673 case Bytecodes::_daload: 674 case Bytecodes::_vaload: 675 case Bytecodes::_aaload: 676 case Bytecodes::_iastore: 677 case Bytecodes::_fastore: 678 case Bytecodes::_bastore: 679 case Bytecodes::_castore: 680 case Bytecodes::_sastore: 681 case Bytecodes::_lastore: 682 case Bytecodes::_dastore: 683 case Bytecodes::_vastore: 684 case Bytecodes::_aastore: 685 case Bytecodes::_pop: 686 case Bytecodes::_pop2: 687 case Bytecodes::_dup: 688 case Bytecodes::_dup_x1: 689 case Bytecodes::_dup_x2: 690 case Bytecodes::_dup2: 691 case Bytecodes::_dup2_x1: 692 case Bytecodes::_dup2_x2: 693 case Bytecodes::_swap: 694 case Bytecodes::_iadd: 695 case Bytecodes::_fadd: 696 case Bytecodes::_isub: 697 case Bytecodes::_fsub: 698 case Bytecodes::_imul: 699 case Bytecodes::_fmul: 700 case Bytecodes::_idiv: 701 case Bytecodes::_fdiv: 702 case Bytecodes::_irem: 703 case Bytecodes::_frem: 704 case Bytecodes::_ishl: 705 case Bytecodes::_ishr: 706 case Bytecodes::_iushr: 707 case Bytecodes::_iand: 708 case Bytecodes::_ior: 709 case Bytecodes::_ixor: 710 case Bytecodes::_l2f: 711 case Bytecodes::_l2i: 712 case Bytecodes::_d2f: 713 case Bytecodes::_d2i: 714 case Bytecodes::_fcmpl: 715 case Bytecodes::_fcmpg: 716 case Bytecodes::_ladd: 717 case Bytecodes::_dadd: 718 case Bytecodes::_lsub: 719 case Bytecodes::_dsub: 720 case Bytecodes::_lmul: 721 case Bytecodes::_dmul: 722 case Bytecodes::_ldiv: 723 case Bytecodes::_ddiv: 724 case Bytecodes::_lrem: 725 case Bytecodes::_drem: 726 case Bytecodes::_land: 727 case Bytecodes::_lor: 728 case Bytecodes::_lxor: 729 case Bytecodes::_ineg: 730 case Bytecodes::_fneg: 731 case Bytecodes::_i2f: 732 case Bytecodes::_f2i: 733 case Bytecodes::_i2c: 734 case Bytecodes::_i2s: 735 case Bytecodes::_i2b: 736 case Bytecodes::_lneg: 737 case Bytecodes::_dneg: 738 case Bytecodes::_l2d: 739 case Bytecodes::_d2l: 740 case Bytecodes::_lshl: 741 case Bytecodes::_lshr: 742 case Bytecodes::_lushr: 743 case Bytecodes::_i2l: 744 case Bytecodes::_i2d: 745 case Bytecodes::_f2l: 746 case Bytecodes::_f2d: 747 case Bytecodes::_lcmp: 748 case Bytecodes::_dcmpl: 749 case Bytecodes::_dcmpg: 750 case Bytecodes::_ifeq: 751 case Bytecodes::_ifne: 752 case Bytecodes::_iflt: 753 case Bytecodes::_ifge: 754 case Bytecodes::_ifgt: 755 case Bytecodes::_ifle: 756 case Bytecodes::_tableswitch: 757 case Bytecodes::_ireturn: 758 case Bytecodes::_freturn: 759 case Bytecodes::_if_icmpeq: 760 case Bytecodes::_if_icmpne: 761 case Bytecodes::_if_icmplt: 762 case Bytecodes::_if_icmpge: 763 case Bytecodes::_if_icmpgt: 764 case Bytecodes::_if_icmple: 765 case Bytecodes::_lreturn: 766 case Bytecodes::_dreturn: 767 case Bytecodes::_if_acmpeq: 768 case Bytecodes::_if_acmpne: 769 case Bytecodes::_jsr: 770 case Bytecodes::_jsr_w: 771 case Bytecodes::_getstatic: 772 case Bytecodes::_putstatic: 773 case Bytecodes::_getfield: 774 case Bytecodes::_putfield: 775 case Bytecodes::_invokevirtual: 776 case Bytecodes::_invokespecial: 777 case Bytecodes::_invokestatic: 778 case Bytecodes::_invokeinterface: 779 case Bytecodes::_invokedynamic: 780 case Bytecodes::_newarray: 781 case Bytecodes::_anewarray: 782 case Bytecodes::_checkcast: 783 case Bytecodes::_arraylength: 784 case Bytecodes::_instanceof: 785 case Bytecodes::_athrow: 786 case Bytecodes::_areturn: 787 case Bytecodes::_vreturn: 788 case Bytecodes::_monitorenter: 789 case Bytecodes::_monitorexit: 790 case Bytecodes::_ifnull: 791 case Bytecodes::_ifnonnull: 792 case Bytecodes::_multianewarray: 793 case Bytecodes::_lookupswitch: 794 case Bytecodes::_vbox: 795 case Bytecodes::_vunbox: 796 // These bytecodes have no effect on the method's locals. 797 break; 798 799 case Bytecodes::_return: 800 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) { 801 // return from Object.init implicitly registers a finalizer 802 // for the receiver if needed, so keep it alive. 803 load_one(0); 804 } 805 break; 806 807 808 case Bytecodes::_lload: 809 case Bytecodes::_dload: 810 load_two(instruction->get_index()); 811 break; 812 813 case Bytecodes::_lload_0: 814 case Bytecodes::_dload_0: 815 load_two(0); 816 break; 817 818 case Bytecodes::_lload_1: 819 case Bytecodes::_dload_1: 820 load_two(1); 821 break; 822 823 case Bytecodes::_lload_2: 824 case Bytecodes::_dload_2: 825 load_two(2); 826 break; 827 828 case Bytecodes::_lload_3: 829 case Bytecodes::_dload_3: 830 load_two(3); 831 break; 832 833 case Bytecodes::_iload: 834 case Bytecodes::_iinc: 835 case Bytecodes::_fload: 836 case Bytecodes::_aload: 837 case Bytecodes::_vload: 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 case Bytecodes::_vstore: 895 store_one(instruction->get_index()); 896 break; 897 898 case Bytecodes::_istore_0: 899 case Bytecodes::_fstore_0: 900 case Bytecodes::_astore_0: 901 store_one(0); 902 break; 903 904 case Bytecodes::_istore_1: 905 case Bytecodes::_fstore_1: 906 case Bytecodes::_astore_1: 907 store_one(1); 908 break; 909 910 case Bytecodes::_istore_2: 911 case Bytecodes::_fstore_2: 912 case Bytecodes::_astore_2: 913 store_one(2); 914 break; 915 916 case Bytecodes::_istore_3: 917 case Bytecodes::_fstore_3: 918 case Bytecodes::_astore_3: 919 store_one(3); 920 break; 921 922 case Bytecodes::_wide: 923 fatal("Iterator should skip this bytecode"); 924 break; 925 926 default: 927 tty->print("unexpected opcode: %d\n", instruction->cur_bc()); 928 ShouldNotReachHere(); 929 break; 930 } 931 } 932 933 void MethodLiveness::BasicBlock::load_two(int local) { 934 load_one(local); 935 load_one(local+1); 936 } 937 938 void MethodLiveness::BasicBlock::load_one(int local) { 939 if (!_kill.at(local)) { 940 _gen.at_put(local, true); 941 } 942 } 943 944 void MethodLiveness::BasicBlock::store_two(int local) { 945 store_one(local); 946 store_one(local+1); 947 } 948 949 void MethodLiveness::BasicBlock::store_one(int local) { 950 if (!_gen.at(local)) { 951 _kill.at_put(local, true); 952 } 953 } 954 955 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) { 956 // These set operations could be combined for efficiency if the 957 // performance of this analysis becomes an issue. 958 _entry.set_union(_normal_exit); 959 _entry.set_difference(_kill); 960 _entry.set_union(_gen); 961 962 // Note that we merge information from our exceptional successors 963 // just once, rather than at individual bytecodes. 964 _entry.set_union(_exception_exit); 965 966 if (TraceLivenessGen) { 967 tty->print_cr(" ** Visiting block at %d **", start_bci()); 968 print_on(tty); 969 } 970 971 int i; 972 for (i=_normal_predecessors->length()-1; i>=0; i--) { 973 BasicBlock *block = _normal_predecessors->at(i); 974 if (block->merge_normal(_entry)) { 975 ml->work_list_add(block); 976 } 977 } 978 for (i=_exception_predecessors->length()-1; i>=0; i--) { 979 BasicBlock *block = _exception_predecessors->at(i); 980 if (block->merge_exception(_entry)) { 981 ml->work_list_add(block); 982 } 983 } 984 } 985 986 bool MethodLiveness::BasicBlock::merge_normal(const BitMap& other) { 987 return _normal_exit.set_union_with_result(other); 988 } 989 990 bool MethodLiveness::BasicBlock::merge_exception(const BitMap& other) { 991 return _exception_exit.set_union_with_result(other); 992 } 993 994 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) { 995 MethodLivenessResult answer(_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 ResourceBitMap g(_gen.size()); g.set_from(_gen); 1008 ResourceBitMap 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.set_union(_normal_exit); 1021 answer.set_difference(_kill); 1022 answer.set_union(_gen); 1023 answer.set_union(_exception_exit); 1024 1025 #ifdef ASSERT 1026 if (bci == start_bci()) { 1027 assert(answer.is_same(_entry), "optimized answer must be accurate"); 1028 } 1029 #endif 1030 1031 return answer; 1032 } 1033 1034 #ifndef PRODUCT 1035 1036 void MethodLiveness::BasicBlock::print_on(outputStream *os) const { 1037 os->print_cr("==================================================================="); 1038 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci); 1039 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length()); 1040 int i; 1041 for (i=0; i < _normal_predecessors->length(); i++) { 1042 os->print(" %4d", _normal_predecessors->at(i)->start_bci()); 1043 } 1044 os->cr(); 1045 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length()); 1046 for (i=0; i < _exception_predecessors->length(); i++) { 1047 os->print(" %4d", _exception_predecessors->at(i)->start_bci()); 1048 } 1049 os->cr(); 1050 os->print (" Normal Exit : "); 1051 _normal_exit.print_on(os); 1052 os->print (" Gen : "); 1053 _gen.print_on(os); 1054 os->print (" Kill : "); 1055 _kill.print_on(os); 1056 os->print (" Exception Exit: "); 1057 _exception_exit.print_on(os); 1058 os->print (" Entry : "); 1059 _entry.print_on(os); 1060 } 1061 1062 #endif // PRODUCT