1 /* 2 * Copyright (c) 1998, 2006, 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 // The MethodLiveness class performs a simple liveness analysis on a method 26 // in order to decide which locals are live (that is, will be used again) at 27 // a particular bytecode index (bci). 28 // 29 // The algorithm goes: 30 // 31 // 1. Break the method into a set of basic blocks. For each basic block we 32 // also keep track of its set of predecessors through normal control flow 33 // and predecessors through exceptional control flow. 34 // 35 // 2. For each basic block, compute two sets, gen (the set of values used before 36 // they are defined) and kill (the set of values defined before they are used) 37 // in the basic block. A basic block "needs" the locals in its gen set to 38 // perform its computation. A basic block "provides" values for the locals in 39 // its kill set, allowing a need from a successor to be ignored. 40 // 41 // 3. Liveness information (the set of locals which are needed) is pushed backwards through 42 // the program, from blocks to their predecessors. We compute and store liveness 43 // information for the normal/exceptional exit paths for each basic block. When 44 // this process reaches a fixed point, we are done. 45 // 46 // 4. When we are asked about the liveness at a particular bci with a basic block, we 47 // compute gen/kill sets which represent execution from that bci to the exit of 48 // its blocks. We then compose this range gen/kill information with the normal 49 // and exceptional exit information for the block to produce liveness information 50 // at that bci. 51 // 52 // The algorithm is approximate in many respects. Notably: 53 // 54 // 1. We do not do the analysis necessary to match jsr's with the appropriate ret. 55 // Instead we make the conservative assumption that any ret can return to any 56 // jsr return site. 57 // 2. Instead of computing the effects of exceptions at every instruction, we 58 // summarize the effects of all exceptional continuations from the block as 59 // a single set (_exception_exit), losing some information but simplifying the 60 // analysis. 61 62 63 # include "incls/_precompiled.incl" 64 # include "incls/_methodLiveness.cpp.incl" 65 66 //-------------------------------------------------------------------------- 67 // The BitCounter class is used for counting the number of bits set in 68 // some BitMap. It is only used when collecting liveness statistics. 69 70 #ifndef PRODUCT 71 72 class BitCounter: public BitMapClosure { 73 private: 74 int _count; 75 public: 76 BitCounter() : _count(0) {} 77 78 // Callback when bit in map is set 79 virtual bool do_bit(size_t offset) { 80 _count++; 81 return true; 82 } 83 84 int count() { 85 return _count; 86 } 87 }; 88 89 90 //-------------------------------------------------------------------------- 91 92 93 // Counts 94 long MethodLiveness::_total_bytes = 0; 95 int MethodLiveness::_total_methods = 0; 96 97 long MethodLiveness::_total_blocks = 0; 98 int MethodLiveness::_max_method_blocks = 0; 99 100 long MethodLiveness::_total_edges = 0; 101 int MethodLiveness::_max_block_edges = 0; 102 103 long MethodLiveness::_total_exc_edges = 0; 104 int MethodLiveness::_max_block_exc_edges = 0; 105 106 long MethodLiveness::_total_method_locals = 0; 107 int MethodLiveness::_max_method_locals = 0; 108 109 long MethodLiveness::_total_locals_queried = 0; 110 long MethodLiveness::_total_live_locals_queried = 0; 111 112 long MethodLiveness::_total_visits = 0; 113 114 #endif 115 116 // Timers 117 elapsedTimer MethodLiveness::_time_build_graph; 118 elapsedTimer MethodLiveness::_time_gen_kill; 119 elapsedTimer MethodLiveness::_time_flow; 120 elapsedTimer MethodLiveness::_time_query; 121 elapsedTimer MethodLiveness::_time_total; 122 123 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method) 124 #ifdef COMPILER1 125 : _bci_block_start((uintptr_t*)arena->Amalloc((method->code_size() >> LogBitsPerByte) + 1), method->code_size()) 126 #endif 127 { 128 _arena = arena; 129 _method = method; 130 _bit_map_size_bits = method->max_locals(); 131 _bit_map_size_words = (_bit_map_size_bits / sizeof(unsigned int)) + 1; 132 133 #ifdef COMPILER1 134 _bci_block_start.clear(); 135 #endif 136 } 137 138 void MethodLiveness::compute_liveness() { 139 #ifndef PRODUCT 140 if (TraceLivenessGen) { 141 tty->print_cr("################################################################"); 142 tty->print("# Computing liveness information for "); 143 method()->print_short_name(); 144 } 145 146 if (TimeLivenessAnalysis) _time_total.start(); 147 #endif 148 149 { 150 TraceTime buildGraph(NULL, &_time_build_graph, TimeLivenessAnalysis); 151 init_basic_blocks(); 152 } 153 { 154 TraceTime genKill(NULL, &_time_gen_kill, TimeLivenessAnalysis); 155 init_gen_kill(); 156 } 157 { 158 TraceTime flow(NULL, &_time_flow, TimeLivenessAnalysis); 159 propagate_liveness(); 160 } 161 162 #ifndef PRODUCT 163 if (TimeLivenessAnalysis) _time_total.stop(); 164 165 if (TimeLivenessAnalysis) { 166 // Collect statistics 167 _total_bytes += method()->code_size(); 168 _total_methods++; 169 170 int num_blocks = _block_count; 171 _total_blocks += num_blocks; 172 _max_method_blocks = MAX2(num_blocks,_max_method_blocks); 173 174 for (int i=0; i<num_blocks; i++) { 175 BasicBlock *block = _block_list[i]; 176 177 int numEdges = block->_normal_predecessors->length(); 178 int numExcEdges = block->_exception_predecessors->length(); 179 180 _total_edges += numEdges; 181 _total_exc_edges += numExcEdges; 182 _max_block_edges = MAX2(numEdges,_max_block_edges); 183 _max_block_exc_edges = MAX2(numExcEdges,_max_block_exc_edges); 184 } 185 186 int numLocals = _bit_map_size_bits; 187 _total_method_locals += numLocals; 188 _max_method_locals = MAX2(numLocals,_max_method_locals); 189 } 190 #endif 191 } 192 193 194 void MethodLiveness::init_basic_blocks() { 195 bool bailout = false; 196 197 int method_len = method()->code_size(); 198 ciMethodBlocks *mblocks = method()->get_method_blocks(); 199 200 // Create an array to store the bci->BasicBlock mapping. 201 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL); 202 203 _block_count = mblocks->num_blocks(); 204 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count); 205 206 // Used for patching up jsr/ret control flow. 207 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5); 208 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5); 209 210 // generate our block list from ciMethodBlocks 211 for (int blk = 0; blk < _block_count; blk++) { 212 ciBlock *cib = mblocks->block(blk); 213 int start_bci = cib->start_bci(); 214 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci()); 215 _block_map->at_put(start_bci, _block_list[blk]); 216 #ifdef COMPILER1 217 // mark all bcis where a new basic block starts 218 _bci_block_start.set_bit(start_bci); 219 #endif // COMPILER1 220 } 221 // fill in the predecessors of blocks 222 ciBytecodeStream bytes(method()); 223 224 for (int blk = 0; blk < _block_count; blk++) { 225 BasicBlock *current_block = _block_list[blk]; 226 int bci = mblocks->block(blk)->control_bci(); 227 228 if (bci == ciBlock::fall_through_bci) { 229 int limit = current_block->limit_bci(); 230 if (limit < method_len) { 231 BasicBlock *next = _block_map->at(limit); 232 assert( next != NULL, "must be a block immediately following this one."); 233 next->add_normal_predecessor(current_block); 234 } 235 continue; 236 } 237 bytes.reset_to_bci(bci); 238 Bytecodes::Code code = bytes.next(); 239 BasicBlock *dest; 240 241 // Now we need to interpret the instruction's effect 242 // on control flow. 243 assert (current_block != NULL, "we must have a current block"); 244 switch (code) { 245 case Bytecodes::_ifeq: 246 case Bytecodes::_ifne: 247 case Bytecodes::_iflt: 248 case Bytecodes::_ifge: 249 case Bytecodes::_ifgt: 250 case Bytecodes::_ifle: 251 case Bytecodes::_if_icmpeq: 252 case Bytecodes::_if_icmpne: 253 case Bytecodes::_if_icmplt: 254 case Bytecodes::_if_icmpge: 255 case Bytecodes::_if_icmpgt: 256 case Bytecodes::_if_icmple: 257 case Bytecodes::_if_acmpeq: 258 case Bytecodes::_if_acmpne: 259 case Bytecodes::_ifnull: 260 case Bytecodes::_ifnonnull: 261 // Two way branch. Set predecessors at each destination. 262 dest = _block_map->at(bytes.next_bci()); 263 assert(dest != NULL, "must be a block immediately following this one."); 264 dest->add_normal_predecessor(current_block); 265 266 dest = _block_map->at(bytes.get_dest()); 267 assert(dest != NULL, "branch desination must start a block."); 268 dest->add_normal_predecessor(current_block); 269 break; 270 case Bytecodes::_goto: 271 dest = _block_map->at(bytes.get_dest()); 272 assert(dest != NULL, "branch desination must start a block."); 273 dest->add_normal_predecessor(current_block); 274 break; 275 case Bytecodes::_goto_w: 276 dest = _block_map->at(bytes.get_far_dest()); 277 assert(dest != NULL, "branch desination must start a block."); 278 dest->add_normal_predecessor(current_block); 279 break; 280 case Bytecodes::_tableswitch: 281 { 282 Bytecode_tableswitch *tableswitch = 283 Bytecode_tableswitch_at(bytes.cur_bcp()); 284 285 int len = tableswitch->length(); 286 287 dest = _block_map->at(bci + tableswitch->default_offset()); 288 assert(dest != NULL, "branch desination must start a block."); 289 dest->add_normal_predecessor(current_block); 290 while (--len >= 0) { 291 dest = _block_map->at(bci + tableswitch->dest_offset_at(len)); 292 assert(dest != NULL, "branch desination must start a block."); 293 dest->add_normal_predecessor(current_block); 294 } 295 break; 296 } 297 298 case Bytecodes::_lookupswitch: 299 { 300 Bytecode_lookupswitch *lookupswitch = 301 Bytecode_lookupswitch_at(bytes.cur_bcp()); 302 303 int npairs = lookupswitch->number_of_pairs(); 304 305 dest = _block_map->at(bci + lookupswitch->default_offset()); 306 assert(dest != NULL, "branch desination must start a block."); 307 dest->add_normal_predecessor(current_block); 308 while(--npairs >= 0) { 309 LookupswitchPair *pair = lookupswitch->pair_at(npairs); 310 dest = _block_map->at( bci + pair->offset()); 311 assert(dest != NULL, "branch desination must start a block."); 312 dest->add_normal_predecessor(current_block); 313 } 314 break; 315 } 316 317 case Bytecodes::_jsr: 318 { 319 assert(bytes.is_wide()==false, "sanity check"); 320 dest = _block_map->at(bytes.get_dest()); 321 assert(dest != NULL, "branch desination must start a block."); 322 dest->add_normal_predecessor(current_block); 323 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 324 assert(jsrExit != NULL, "jsr return bci must start a block."); 325 jsr_exit_list->append(jsrExit); 326 break; 327 } 328 case Bytecodes::_jsr_w: 329 { 330 dest = _block_map->at(bytes.get_far_dest()); 331 assert(dest != NULL, "branch desination must start a block."); 332 dest->add_normal_predecessor(current_block); 333 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 334 assert(jsrExit != NULL, "jsr return bci must start a block."); 335 jsr_exit_list->append(jsrExit); 336 break; 337 } 338 339 case Bytecodes::_wide: 340 assert(false, "wide opcodes should not be seen here"); 341 break; 342 case Bytecodes::_athrow: 343 case Bytecodes::_ireturn: 344 case Bytecodes::_lreturn: 345 case Bytecodes::_freturn: 346 case Bytecodes::_dreturn: 347 case Bytecodes::_areturn: 348 case Bytecodes::_return: 349 // These opcodes are not the normal predecessors of any other opcodes. 350 break; 351 case Bytecodes::_ret: 352 // We will patch up jsr/rets in a subsequent pass. 353 ret_list->append(current_block); 354 break; 355 case Bytecodes::_breakpoint: 356 // Bail out of there are breakpoints in here. 357 bailout = true; 358 break; 359 default: 360 // Do nothing. 361 break; 362 } 363 } 364 // Patch up the jsr/ret's. We conservatively assume that any ret 365 // can return to any jsr site. 366 int ret_list_len = ret_list->length(); 367 int jsr_exit_list_len = jsr_exit_list->length(); 368 if (ret_list_len > 0 && jsr_exit_list_len > 0) { 369 for (int i = jsr_exit_list_len - 1; i >= 0; i--) { 370 BasicBlock *jsrExit = jsr_exit_list->at(i); 371 for (int i = ret_list_len - 1; i >= 0; i--) { 372 jsrExit->add_normal_predecessor(ret_list->at(i)); 373 } 374 } 375 } 376 377 // Compute exception edges. 378 for (int b=_block_count-1; b >= 0; b--) { 379 BasicBlock *block = _block_list[b]; 380 int block_start = block->start_bci(); 381 int block_limit = block->limit_bci(); 382 ciExceptionHandlerStream handlers(method()); 383 for (; !handlers.is_done(); handlers.next()) { 384 ciExceptionHandler* handler = handlers.handler(); 385 int start = handler->start(); 386 int limit = handler->limit(); 387 int handler_bci = handler->handler_bci(); 388 389 int intersect_start = MAX2(block_start, start); 390 int intersect_limit = MIN2(block_limit, limit); 391 if (intersect_start < intersect_limit) { 392 // The catch range has a nonempty intersection with this 393 // basic block. That means this basic block can be an 394 // exceptional predecessor. 395 _block_map->at(handler_bci)->add_exception_predecessor(block); 396 397 if (handler->is_catch_all()) { 398 // This is a catch-all block. 399 if (intersect_start == block_start && intersect_limit == block_limit) { 400 // The basic block is entirely contained in this catch-all block. 401 // Skip the rest of the exception handlers -- they can never be 402 // reached in execution. 403 break; 404 } 405 } 406 } 407 } 408 } 409 } 410 411 void MethodLiveness::init_gen_kill() { 412 for (int i=_block_count-1; i >= 0; i--) { 413 _block_list[i]->compute_gen_kill(method()); 414 } 415 } 416 417 void MethodLiveness::propagate_liveness() { 418 int num_blocks = _block_count; 419 BasicBlock *block; 420 421 // We start our work list off with all blocks in it. 422 // Alternately, we could start off the work list with the list of all 423 // blocks which could exit the method directly, along with one block 424 // from any infinite loop. If this matters, it can be changed. It 425 // may not be clear from looking at the code, but the order of the 426 // workList will be the opposite of the creation order of the basic 427 // blocks, which should be decent for quick convergence (with the 428 // possible exception of exception handlers, which are all created 429 // early). 430 _work_list = NULL; 431 for (int i = 0; i < num_blocks; i++) { 432 block = _block_list[i]; 433 block->set_next(_work_list); 434 block->set_on_work_list(true); 435 _work_list = block; 436 } 437 438 439 while ((block = work_list_get()) != NULL) { 440 block->propagate(this); 441 NOT_PRODUCT(_total_visits++;) 442 } 443 } 444 445 void MethodLiveness::work_list_add(BasicBlock *block) { 446 if (!block->on_work_list()) { 447 block->set_next(_work_list); 448 block->set_on_work_list(true); 449 _work_list = block; 450 } 451 } 452 453 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() { 454 BasicBlock *block = _work_list; 455 if (block != NULL) { 456 block->set_on_work_list(false); 457 _work_list = block->next(); 458 } 459 return block; 460 } 461 462 463 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) { 464 int bci = entry_bci; 465 bool is_entry = false; 466 if (entry_bci == InvocationEntryBci) { 467 is_entry = true; 468 bci = 0; 469 } 470 471 MethodLivenessResult answer((uintptr_t*)NULL,0); 472 473 if (_block_count > 0) { 474 if (TimeLivenessAnalysis) _time_total.start(); 475 if (TimeLivenessAnalysis) _time_query.start(); 476 477 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" ); 478 BasicBlock *block = _block_map->at(bci); 479 // We may not be at the block start, so search backwards to find the block 480 // containing bci. 481 int t = bci; 482 while (block == NULL && t > 0) { 483 block = _block_map->at(--t); 484 } 485 assert( block != NULL, "invalid bytecode index; must be instruction index" ); 486 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci."); 487 488 answer = block->get_liveness_at(method(), bci); 489 490 if (is_entry && method()->is_synchronized() && !method()->is_static()) { 491 // Synchronized methods use the receiver once on entry. 492 answer.at_put(0, true); 493 } 494 495 #ifndef PRODUCT 496 if (TraceLivenessQuery) { 497 tty->print("Liveness query of "); 498 method()->print_short_name(); 499 tty->print(" @ %d : result is ", bci); 500 answer.print_on(tty); 501 } 502 503 if (TimeLivenessAnalysis) _time_query.stop(); 504 if (TimeLivenessAnalysis) _time_total.stop(); 505 #endif 506 } 507 508 #ifndef PRODUCT 509 if (TimeLivenessAnalysis) { 510 // Collect statistics. 511 _total_locals_queried += _bit_map_size_bits; 512 BitCounter counter; 513 answer.iterate(&counter); 514 _total_live_locals_queried += counter.count(); 515 } 516 #endif 517 518 return answer; 519 } 520 521 522 #ifndef PRODUCT 523 524 void MethodLiveness::print_times() { 525 tty->print_cr ("Accumulated liveness analysis times/statistics:"); 526 tty->print_cr ("-----------------------------------------------"); 527 tty->print_cr (" Total : %3.3f sec.", _time_total.seconds()); 528 tty->print_cr (" Build graph : %3.3f sec. (%2.2f%%)", _time_build_graph.seconds(), 529 _time_build_graph.seconds() * 100 / _time_total.seconds()); 530 tty->print_cr (" Gen / Kill : %3.3f sec. (%2.2f%%)", _time_gen_kill.seconds(), 531 _time_gen_kill.seconds() * 100 / _time_total.seconds()); 532 tty->print_cr (" Dataflow : %3.3f sec. (%2.2f%%)", _time_flow.seconds(), 533 _time_flow.seconds() * 100 / _time_total.seconds()); 534 tty->print_cr (" Query : %3.3f sec. (%2.2f%%)", _time_query.seconds(), 535 _time_query.seconds() * 100 / _time_total.seconds()); 536 tty->print_cr (" #bytes : %8d (%3.0f bytes per sec)", 537 _total_bytes, 538 _total_bytes / _time_total.seconds()); 539 tty->print_cr (" #methods : %8d (%3.0f methods per sec)", 540 _total_methods, 541 _total_methods / _time_total.seconds()); 542 tty->print_cr (" avg locals : %3.3f max locals : %3d", 543 (float)_total_method_locals / _total_methods, 544 _max_method_locals); 545 tty->print_cr (" avg blocks : %3.3f max blocks : %3d", 546 (float)_total_blocks / _total_methods, 547 _max_method_blocks); 548 tty->print_cr (" avg bytes : %3.3f", 549 (float)_total_bytes / _total_methods); 550 tty->print_cr (" #blocks : %8d", 551 _total_blocks); 552 tty->print_cr (" avg normal predecessors : %3.3f max normal predecessors : %3d", 553 (float)_total_edges / _total_blocks, 554 _max_block_edges); 555 tty->print_cr (" avg exception predecessors : %3.3f max exception predecessors : %3d", 556 (float)_total_exc_edges / _total_blocks, 557 _max_block_exc_edges); 558 tty->print_cr (" avg visits : %3.3f", 559 (float)_total_visits / _total_blocks); 560 tty->print_cr (" #locals queried : %8d #live : %8d %%live : %2.2f%%", 561 _total_locals_queried, 562 _total_live_locals_queried, 563 100.0 * _total_live_locals_queried / _total_locals_queried); 564 } 565 566 #endif 567 568 569 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) : 570 _gen((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 571 analyzer->bit_map_size_bits()), 572 _kill((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 573 analyzer->bit_map_size_bits()), 574 _entry((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 575 analyzer->bit_map_size_bits()), 576 _normal_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 577 analyzer->bit_map_size_bits()), 578 _exception_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 579 analyzer->bit_map_size_bits()), 580 _last_bci(-1) { 581 _analyzer = analyzer; 582 _start_bci = start; 583 _limit_bci = limit; 584 _normal_predecessors = 585 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 586 _exception_predecessors = 587 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 588 _normal_exit.clear(); 589 _exception_exit.clear(); 590 _entry.clear(); 591 592 // this initialization is not strictly necessary. 593 // _gen and _kill are cleared at the beginning of compute_gen_kill_range() 594 _gen.clear(); 595 _kill.clear(); 596 } 597 598 599 600 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) { 601 int start = _start_bci; 602 int limit = _limit_bci; 603 604 if (TraceLivenessGen) { 605 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci); 606 } 607 608 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors; 609 610 assert (start < split_bci && split_bci < limit, "improper split"); 611 612 // Make a new block to cover the first half of the range. 613 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci); 614 615 // Assign correct values to the second half (this) 616 _normal_predecessors = first_half->_normal_predecessors; 617 _start_bci = split_bci; 618 add_normal_predecessor(first_half); 619 620 // Assign correct predecessors to the new first half 621 first_half->_normal_predecessors = save_predecessors; 622 623 return first_half; 624 } 625 626 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) { 627 ciBytecodeStream bytes(method); 628 bytes.reset_to_bci(start_bci()); 629 bytes.set_max_bci(limit_bci()); 630 compute_gen_kill_range(&bytes); 631 632 } 633 634 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) { 635 _gen.clear(); 636 _kill.clear(); 637 638 while (bytes->next() != ciBytecodeStream::EOBC()) { 639 compute_gen_kill_single(bytes); 640 } 641 } 642 643 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) { 644 int localNum; 645 646 // We prohibit _gen and _kill from having locals in common. If we 647 // know that one is definitely going to be applied before the other, 648 // we could save some computation time by relaxing this prohibition. 649 650 switch (instruction->cur_bc()) { 651 case Bytecodes::_nop: 652 case Bytecodes::_goto: 653 case Bytecodes::_goto_w: 654 case Bytecodes::_aconst_null: 655 case Bytecodes::_new: 656 case Bytecodes::_iconst_m1: 657 case Bytecodes::_iconst_0: 658 case Bytecodes::_iconst_1: 659 case Bytecodes::_iconst_2: 660 case Bytecodes::_iconst_3: 661 case Bytecodes::_iconst_4: 662 case Bytecodes::_iconst_5: 663 case Bytecodes::_fconst_0: 664 case Bytecodes::_fconst_1: 665 case Bytecodes::_fconst_2: 666 case Bytecodes::_bipush: 667 case Bytecodes::_sipush: 668 case Bytecodes::_lconst_0: 669 case Bytecodes::_lconst_1: 670 case Bytecodes::_dconst_0: 671 case Bytecodes::_dconst_1: 672 case Bytecodes::_ldc2_w: 673 case Bytecodes::_ldc: 674 case Bytecodes::_ldc_w: 675 case Bytecodes::_iaload: 676 case Bytecodes::_faload: 677 case Bytecodes::_baload: 678 case Bytecodes::_caload: 679 case Bytecodes::_saload: 680 case Bytecodes::_laload: 681 case Bytecodes::_daload: 682 case Bytecodes::_aaload: 683 case Bytecodes::_iastore: 684 case Bytecodes::_fastore: 685 case Bytecodes::_bastore: 686 case Bytecodes::_castore: 687 case Bytecodes::_sastore: 688 case Bytecodes::_lastore: 689 case Bytecodes::_dastore: 690 case Bytecodes::_aastore: 691 case Bytecodes::_pop: 692 case Bytecodes::_pop2: 693 case Bytecodes::_dup: 694 case Bytecodes::_dup_x1: 695 case Bytecodes::_dup_x2: 696 case Bytecodes::_dup2: 697 case Bytecodes::_dup2_x1: 698 case Bytecodes::_dup2_x2: 699 case Bytecodes::_swap: 700 case Bytecodes::_iadd: 701 case Bytecodes::_fadd: 702 case Bytecodes::_isub: 703 case Bytecodes::_fsub: 704 case Bytecodes::_imul: 705 case Bytecodes::_fmul: 706 case Bytecodes::_idiv: 707 case Bytecodes::_fdiv: 708 case Bytecodes::_irem: 709 case Bytecodes::_frem: 710 case Bytecodes::_ishl: 711 case Bytecodes::_ishr: 712 case Bytecodes::_iushr: 713 case Bytecodes::_iand: 714 case Bytecodes::_ior: 715 case Bytecodes::_ixor: 716 case Bytecodes::_l2f: 717 case Bytecodes::_l2i: 718 case Bytecodes::_d2f: 719 case Bytecodes::_d2i: 720 case Bytecodes::_fcmpl: 721 case Bytecodes::_fcmpg: 722 case Bytecodes::_ladd: 723 case Bytecodes::_dadd: 724 case Bytecodes::_lsub: 725 case Bytecodes::_dsub: 726 case Bytecodes::_lmul: 727 case Bytecodes::_dmul: 728 case Bytecodes::_ldiv: 729 case Bytecodes::_ddiv: 730 case Bytecodes::_lrem: 731 case Bytecodes::_drem: 732 case Bytecodes::_land: 733 case Bytecodes::_lor: 734 case Bytecodes::_lxor: 735 case Bytecodes::_ineg: 736 case Bytecodes::_fneg: 737 case Bytecodes::_i2f: 738 case Bytecodes::_f2i: 739 case Bytecodes::_i2c: 740 case Bytecodes::_i2s: 741 case Bytecodes::_i2b: 742 case Bytecodes::_lneg: 743 case Bytecodes::_dneg: 744 case Bytecodes::_l2d: 745 case Bytecodes::_d2l: 746 case Bytecodes::_lshl: 747 case Bytecodes::_lshr: 748 case Bytecodes::_lushr: 749 case Bytecodes::_i2l: 750 case Bytecodes::_i2d: 751 case Bytecodes::_f2l: 752 case Bytecodes::_f2d: 753 case Bytecodes::_lcmp: 754 case Bytecodes::_dcmpl: 755 case Bytecodes::_dcmpg: 756 case Bytecodes::_ifeq: 757 case Bytecodes::_ifne: 758 case Bytecodes::_iflt: 759 case Bytecodes::_ifge: 760 case Bytecodes::_ifgt: 761 case Bytecodes::_ifle: 762 case Bytecodes::_tableswitch: 763 case Bytecodes::_ireturn: 764 case Bytecodes::_freturn: 765 case Bytecodes::_if_icmpeq: 766 case Bytecodes::_if_icmpne: 767 case Bytecodes::_if_icmplt: 768 case Bytecodes::_if_icmpge: 769 case Bytecodes::_if_icmpgt: 770 case Bytecodes::_if_icmple: 771 case Bytecodes::_lreturn: 772 case Bytecodes::_dreturn: 773 case Bytecodes::_if_acmpeq: 774 case Bytecodes::_if_acmpne: 775 case Bytecodes::_jsr: 776 case Bytecodes::_jsr_w: 777 case Bytecodes::_getstatic: 778 case Bytecodes::_putstatic: 779 case Bytecodes::_getfield: 780 case Bytecodes::_putfield: 781 case Bytecodes::_invokevirtual: 782 case Bytecodes::_invokespecial: 783 case Bytecodes::_invokestatic: 784 case Bytecodes::_invokeinterface: 785 case Bytecodes::_invokedynamic: 786 case Bytecodes::_newarray: 787 case Bytecodes::_anewarray: 788 case Bytecodes::_checkcast: 789 case Bytecodes::_arraylength: 790 case Bytecodes::_instanceof: 791 case Bytecodes::_athrow: 792 case Bytecodes::_areturn: 793 case Bytecodes::_monitorenter: 794 case Bytecodes::_monitorexit: 795 case Bytecodes::_ifnull: 796 case Bytecodes::_ifnonnull: 797 case Bytecodes::_multianewarray: 798 case Bytecodes::_lookupswitch: 799 // These bytecodes have no effect on the method's locals. 800 break; 801 802 case Bytecodes::_return: 803 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) { 804 // return from Object.init implicitly registers a finalizer 805 // for the receiver if needed, so keep it alive. 806 load_one(0); 807 } 808 break; 809 810 811 case Bytecodes::_lload: 812 case Bytecodes::_dload: 813 load_two(instruction->get_index()); 814 break; 815 816 case Bytecodes::_lload_0: 817 case Bytecodes::_dload_0: 818 load_two(0); 819 break; 820 821 case Bytecodes::_lload_1: 822 case Bytecodes::_dload_1: 823 load_two(1); 824 break; 825 826 case Bytecodes::_lload_2: 827 case Bytecodes::_dload_2: 828 load_two(2); 829 break; 830 831 case Bytecodes::_lload_3: 832 case Bytecodes::_dload_3: 833 load_two(3); 834 break; 835 836 case Bytecodes::_iload: 837 case Bytecodes::_iinc: 838 case Bytecodes::_fload: 839 case Bytecodes::_aload: 840 case Bytecodes::_ret: 841 load_one(instruction->get_index()); 842 break; 843 844 case Bytecodes::_iload_0: 845 case Bytecodes::_fload_0: 846 case Bytecodes::_aload_0: 847 load_one(0); 848 break; 849 850 case Bytecodes::_iload_1: 851 case Bytecodes::_fload_1: 852 case Bytecodes::_aload_1: 853 load_one(1); 854 break; 855 856 case Bytecodes::_iload_2: 857 case Bytecodes::_fload_2: 858 case Bytecodes::_aload_2: 859 load_one(2); 860 break; 861 862 case Bytecodes::_iload_3: 863 case Bytecodes::_fload_3: 864 case Bytecodes::_aload_3: 865 load_one(3); 866 break; 867 868 case Bytecodes::_lstore: 869 case Bytecodes::_dstore: 870 store_two(localNum = instruction->get_index()); 871 break; 872 873 case Bytecodes::_lstore_0: 874 case Bytecodes::_dstore_0: 875 store_two(0); 876 break; 877 878 case Bytecodes::_lstore_1: 879 case Bytecodes::_dstore_1: 880 store_two(1); 881 break; 882 883 case Bytecodes::_lstore_2: 884 case Bytecodes::_dstore_2: 885 store_two(2); 886 break; 887 888 case Bytecodes::_lstore_3: 889 case Bytecodes::_dstore_3: 890 store_two(3); 891 break; 892 893 case Bytecodes::_istore: 894 case Bytecodes::_fstore: 895 case Bytecodes::_astore: 896 store_one(instruction->get_index()); 897 break; 898 899 case Bytecodes::_istore_0: 900 case Bytecodes::_fstore_0: 901 case Bytecodes::_astore_0: 902 store_one(0); 903 break; 904 905 case Bytecodes::_istore_1: 906 case Bytecodes::_fstore_1: 907 case Bytecodes::_astore_1: 908 store_one(1); 909 break; 910 911 case Bytecodes::_istore_2: 912 case Bytecodes::_fstore_2: 913 case Bytecodes::_astore_2: 914 store_one(2); 915 break; 916 917 case Bytecodes::_istore_3: 918 case Bytecodes::_fstore_3: 919 case Bytecodes::_astore_3: 920 store_one(3); 921 break; 922 923 case Bytecodes::_wide: 924 fatal("Iterator should skip this bytecode"); 925 break; 926 927 default: 928 tty->print("unexpected opcode: %d\n", instruction->cur_bc()); 929 ShouldNotReachHere(); 930 break; 931 } 932 } 933 934 void MethodLiveness::BasicBlock::load_two(int local) { 935 load_one(local); 936 load_one(local+1); 937 } 938 939 void MethodLiveness::BasicBlock::load_one(int local) { 940 if (!_kill.at(local)) { 941 _gen.at_put(local, true); 942 } 943 } 944 945 void MethodLiveness::BasicBlock::store_two(int local) { 946 store_one(local); 947 store_one(local+1); 948 } 949 950 void MethodLiveness::BasicBlock::store_one(int local) { 951 if (!_gen.at(local)) { 952 _kill.at_put(local, true); 953 } 954 } 955 956 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) { 957 // These set operations could be combined for efficiency if the 958 // performance of this analysis becomes an issue. 959 _entry.set_union(_normal_exit); 960 _entry.set_difference(_kill); 961 _entry.set_union(_gen); 962 963 // Note that we merge information from our exceptional successors 964 // just once, rather than at individual bytecodes. 965 _entry.set_union(_exception_exit); 966 967 if (TraceLivenessGen) { 968 tty->print_cr(" ** Visiting block at %d **", start_bci()); 969 print_on(tty); 970 } 971 972 int i; 973 for (i=_normal_predecessors->length()-1; i>=0; i--) { 974 BasicBlock *block = _normal_predecessors->at(i); 975 if (block->merge_normal(_entry)) { 976 ml->work_list_add(block); 977 } 978 } 979 for (i=_exception_predecessors->length()-1; i>=0; i--) { 980 BasicBlock *block = _exception_predecessors->at(i); 981 if (block->merge_exception(_entry)) { 982 ml->work_list_add(block); 983 } 984 } 985 } 986 987 bool MethodLiveness::BasicBlock::merge_normal(BitMap other) { 988 return _normal_exit.set_union_with_result(other); 989 } 990 991 bool MethodLiveness::BasicBlock::merge_exception(BitMap other) { 992 return _exception_exit.set_union_with_result(other); 993 } 994 995 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) { 996 MethodLivenessResult answer(NEW_RESOURCE_ARRAY(uintptr_t, _analyzer->bit_map_size_words()), 997 _analyzer->bit_map_size_bits()); 998 answer.set_is_valid(); 999 1000 #ifndef ASSERT 1001 if (bci == start_bci()) { 1002 answer.set_from(_entry); 1003 return answer; 1004 } 1005 #endif 1006 1007 #ifdef ASSERT 1008 ResourceMark rm; 1009 BitMap g(_gen.size()); g.set_from(_gen); 1010 BitMap k(_kill.size()); k.set_from(_kill); 1011 #endif 1012 if (_last_bci != bci || trueInDebug) { 1013 ciBytecodeStream bytes(method); 1014 bytes.reset_to_bci(bci); 1015 bytes.set_max_bci(limit_bci()); 1016 compute_gen_kill_range(&bytes); 1017 assert(_last_bci != bci || 1018 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect"); 1019 _last_bci = bci; 1020 } 1021 1022 answer.clear(); 1023 answer.set_union(_normal_exit); 1024 answer.set_difference(_kill); 1025 answer.set_union(_gen); 1026 answer.set_union(_exception_exit); 1027 1028 #ifdef ASSERT 1029 if (bci == start_bci()) { 1030 assert(answer.is_same(_entry), "optimized answer must be accurate"); 1031 } 1032 #endif 1033 1034 return answer; 1035 } 1036 1037 #ifndef PRODUCT 1038 1039 void MethodLiveness::BasicBlock::print_on(outputStream *os) const { 1040 os->print_cr("==================================================================="); 1041 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci); 1042 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length()); 1043 int i; 1044 for (i=0; i < _normal_predecessors->length(); i++) { 1045 os->print(" %4d", _normal_predecessors->at(i)->start_bci()); 1046 } 1047 os->cr(); 1048 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length()); 1049 for (i=0; i < _exception_predecessors->length(); i++) { 1050 os->print(" %4d", _exception_predecessors->at(i)->start_bci()); 1051 } 1052 os->cr(); 1053 os->print (" Normal Exit : "); 1054 _normal_exit.print_on(os); 1055 os->print (" Gen : "); 1056 _gen.print_on(os); 1057 os->print (" Kill : "); 1058 _kill.print_on(os); 1059 os->print (" Exception Exit: "); 1060 _exception_exit.print_on(os); 1061 os->print (" Entry : "); 1062 _entry.print_on(os); 1063 } 1064 1065 #endif // PRODUCT