1 /* 2 * Copyright (c) 1998, 2014, 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 "utilities/bitMap.inline.hpp" 34 35 // The MethodLiveness class performs a simple liveness analysis on a method 36 // in order to decide which locals are live (that is, will be used again) at 37 // a particular bytecode index (bci). 38 // 39 // The algorithm goes: 40 // 41 // 1. Break the method into a set of basic blocks. For each basic block we 42 // also keep track of its set of predecessors through normal control flow 43 // and predecessors through exceptional control flow. 44 // 45 // 2. For each basic block, compute two sets, gen (the set of values used before 46 // they are defined) and kill (the set of values defined before they are used) 47 // in the basic block. A basic block "needs" the locals in its gen set to 48 // perform its computation. A basic block "provides" values for the locals in 49 // its kill set, allowing a need from a successor to be ignored. 50 // 51 // 3. Liveness information (the set of locals which are needed) is pushed backwards through 52 // the program, from blocks to their predecessors. We compute and store liveness 53 // information for the normal/exceptional exit paths for each basic block. When 54 // this process reaches a fixed point, we are done. 55 // 56 // 4. When we are asked about the liveness at a particular bci with a basic block, we 57 // compute gen/kill sets which represent execution from that bci to the exit of 58 // its blocks. We then compose this range gen/kill information with the normal 59 // and exceptional exit information for the block to produce liveness information 60 // at that bci. 61 // 62 // The algorithm is approximate in many respects. Notably: 63 // 64 // 1. We do not do the analysis necessary to match jsr's with the appropriate ret. 65 // Instead we make the conservative assumption that any ret can return to any 66 // jsr return site. 67 // 2. Instead of computing the effects of exceptions at every instruction, we 68 // summarize the effects of all exceptional continuations from the block as 69 // a single set (_exception_exit), losing some information but simplifying the 70 // analysis. 71 72 73 //-------------------------------------------------------------------------- 74 // The BitCounter class is used for counting the number of bits set in 75 // some BitMap. It is only used when collecting liveness statistics. 76 77 #ifndef PRODUCT 78 79 class BitCounter: public BitMapClosure { 80 private: 81 int _count; 82 public: 83 BitCounter() : _count(0) {} 84 85 // Callback when bit in map is set 86 virtual bool do_bit(size_t offset) { 87 _count++; 88 return true; 89 } 90 91 int count() { 92 return _count; 93 } 94 }; 95 96 97 //-------------------------------------------------------------------------- 98 99 100 // Counts 101 long MethodLiveness::_total_bytes = 0; 102 int MethodLiveness::_total_methods = 0; 103 104 long MethodLiveness::_total_blocks = 0; 105 int MethodLiveness::_max_method_blocks = 0; 106 107 long MethodLiveness::_total_edges = 0; 108 int MethodLiveness::_max_block_edges = 0; 109 110 long MethodLiveness::_total_exc_edges = 0; 111 int MethodLiveness::_max_block_exc_edges = 0; 112 113 long MethodLiveness::_total_method_locals = 0; 114 int MethodLiveness::_max_method_locals = 0; 115 116 long MethodLiveness::_total_locals_queried = 0; 117 long MethodLiveness::_total_live_locals_queried = 0; 118 119 long MethodLiveness::_total_visits = 0; 120 121 #endif 122 123 // Timers 124 elapsedTimer MethodLiveness::_time_build_graph; 125 elapsedTimer MethodLiveness::_time_gen_kill; 126 elapsedTimer MethodLiveness::_time_flow; 127 elapsedTimer MethodLiveness::_time_query; 128 elapsedTimer MethodLiveness::_time_total; 129 130 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method) 131 #ifdef COMPILER1 132 : _bci_block_start((uintptr_t*)arena->Amalloc((method->code_size() >> LogBitsPerByte) + 1), method->code_size()) 133 #endif 134 { 135 _arena = arena; 136 _method = method; 137 _bit_map_size_bits = method->max_locals(); 138 _bit_map_size_words = (_bit_map_size_bits / sizeof(unsigned int)) + 1; 139 140 #ifdef COMPILER1 141 _bci_block_start.clear(); 142 #endif 143 } 144 145 void MethodLiveness::compute_liveness() { 146 #ifndef PRODUCT 147 if (TraceLivenessGen) { 148 tty->print_cr("################################################################"); 149 tty->print("# Computing liveness information for "); 150 method()->print_short_name(); 151 } 152 153 if (TimeLivenessAnalysis) _time_total.start(); 154 #endif 155 156 { 157 TraceTime buildGraph(NULL, &_time_build_graph, TimeLivenessAnalysis); 158 init_basic_blocks(); 159 } 160 { 161 TraceTime genKill(NULL, &_time_gen_kill, TimeLivenessAnalysis); 162 init_gen_kill(); 163 } 164 { 165 TraceTime flow(NULL, &_time_flow, TimeLivenessAnalysis); 166 propagate_liveness(); 167 } 168 169 #ifndef PRODUCT 170 if (TimeLivenessAnalysis) _time_total.stop(); 171 172 if (TimeLivenessAnalysis) { 173 // Collect statistics 174 _total_bytes += method()->code_size(); 175 _total_methods++; 176 177 int num_blocks = _block_count; 178 _total_blocks += num_blocks; 179 _max_method_blocks = MAX2(num_blocks,_max_method_blocks); 180 181 for (int i=0; i<num_blocks; i++) { 182 BasicBlock *block = _block_list[i]; 183 184 int numEdges = block->_normal_predecessors->length(); 185 int numExcEdges = block->_exception_predecessors->length(); 186 187 _total_edges += numEdges; 188 _total_exc_edges += numExcEdges; 189 _max_block_edges = MAX2(numEdges,_max_block_edges); 190 _max_block_exc_edges = MAX2(numExcEdges,_max_block_exc_edges); 191 } 192 193 int numLocals = _bit_map_size_bits; 194 _total_method_locals += numLocals; 195 _max_method_locals = MAX2(numLocals,_max_method_locals); 196 } 197 #endif 198 } 199 200 201 void MethodLiveness::init_basic_blocks() { 202 bool bailout = false; 203 204 int method_len = method()->code_size(); 205 ciMethodBlocks *mblocks = method()->get_method_blocks(); 206 207 // Create an array to store the bci->BasicBlock mapping. 208 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL); 209 210 _block_count = mblocks->num_blocks(); 211 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count); 212 213 // Used for patching up jsr/ret control flow. 214 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5); 215 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5); 216 217 // generate our block list from ciMethodBlocks 218 for (int blk = 0; blk < _block_count; blk++) { 219 ciBlock *cib = mblocks->block(blk); 220 int start_bci = cib->start_bci(); 221 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci()); 222 _block_map->at_put(start_bci, _block_list[blk]); 223 #ifdef COMPILER1 224 // mark all bcis where a new basic block starts 225 _bci_block_start.set_bit(start_bci); 226 #endif // COMPILER1 227 } 228 // fill in the predecessors of blocks 229 ciBytecodeStream bytes(method()); 230 231 for (int blk = 0; blk < _block_count; blk++) { 232 BasicBlock *current_block = _block_list[blk]; 233 int bci = mblocks->block(blk)->control_bci(); 234 235 if (bci == ciBlock::fall_through_bci) { 236 int limit = current_block->limit_bci(); 237 if (limit < method_len) { 238 BasicBlock *next = _block_map->at(limit); 239 assert( next != NULL, "must be a block immediately following this one."); 240 next->add_normal_predecessor(current_block); 241 } 242 continue; 243 } 244 bytes.reset_to_bci(bci); 245 Bytecodes::Code code = bytes.next(); 246 BasicBlock *dest; 247 248 // Now we need to interpret the instruction's effect 249 // on control flow. 250 assert (current_block != NULL, "we must have a current block"); 251 switch (code) { 252 case Bytecodes::_ifeq: 253 case Bytecodes::_ifne: 254 case Bytecodes::_iflt: 255 case Bytecodes::_ifge: 256 case Bytecodes::_ifgt: 257 case Bytecodes::_ifle: 258 case Bytecodes::_if_icmpeq: 259 case Bytecodes::_if_icmpne: 260 case Bytecodes::_if_icmplt: 261 case Bytecodes::_if_icmpge: 262 case Bytecodes::_if_icmpgt: 263 case Bytecodes::_if_icmple: 264 case Bytecodes::_if_acmpeq: 265 case Bytecodes::_if_acmpne: 266 case Bytecodes::_ifnull: 267 case Bytecodes::_ifnonnull: 268 // Two way branch. Set predecessors at each destination. 269 dest = _block_map->at(bytes.next_bci()); 270 assert(dest != NULL, "must be a block immediately following this one."); 271 dest->add_normal_predecessor(current_block); 272 273 dest = _block_map->at(bytes.get_dest()); 274 assert(dest != NULL, "branch desination must start a block."); 275 dest->add_normal_predecessor(current_block); 276 break; 277 case Bytecodes::_goto: 278 dest = _block_map->at(bytes.get_dest()); 279 assert(dest != NULL, "branch desination must start a block."); 280 dest->add_normal_predecessor(current_block); 281 break; 282 case Bytecodes::_goto_w: 283 dest = _block_map->at(bytes.get_far_dest()); 284 assert(dest != NULL, "branch desination must start a block."); 285 dest->add_normal_predecessor(current_block); 286 break; 287 case Bytecodes::_tableswitch: 288 { 289 Bytecode_tableswitch tableswitch(&bytes); 290 291 int len = tableswitch.length(); 292 293 dest = _block_map->at(bci + tableswitch.default_offset()); 294 assert(dest != NULL, "branch desination must start a block."); 295 dest->add_normal_predecessor(current_block); 296 while (--len >= 0) { 297 dest = _block_map->at(bci + tableswitch.dest_offset_at(len)); 298 assert(dest != NULL, "branch desination must start a block."); 299 dest->add_normal_predecessor(current_block); 300 } 301 break; 302 } 303 304 case Bytecodes::_lookupswitch: 305 { 306 Bytecode_lookupswitch lookupswitch(&bytes); 307 308 int npairs = lookupswitch.number_of_pairs(); 309 310 dest = _block_map->at(bci + lookupswitch.default_offset()); 311 assert(dest != NULL, "branch desination must start a block."); 312 dest->add_normal_predecessor(current_block); 313 while(--npairs >= 0) { 314 LookupswitchPair pair = lookupswitch.pair_at(npairs); 315 dest = _block_map->at( bci + pair.offset()); 316 assert(dest != NULL, "branch desination must start a block."); 317 dest->add_normal_predecessor(current_block); 318 } 319 break; 320 } 321 322 case Bytecodes::_jsr: 323 { 324 assert(bytes.is_wide()==false, "sanity check"); 325 dest = _block_map->at(bytes.get_dest()); 326 assert(dest != NULL, "branch desination must start a block."); 327 dest->add_normal_predecessor(current_block); 328 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 329 assert(jsrExit != NULL, "jsr return bci must start a block."); 330 jsr_exit_list->append(jsrExit); 331 break; 332 } 333 case Bytecodes::_jsr_w: 334 { 335 dest = _block_map->at(bytes.get_far_dest()); 336 assert(dest != NULL, "branch desination must start a block."); 337 dest->add_normal_predecessor(current_block); 338 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 339 assert(jsrExit != NULL, "jsr return bci must start a block."); 340 jsr_exit_list->append(jsrExit); 341 break; 342 } 343 344 case Bytecodes::_wide: 345 assert(false, "wide opcodes should not be seen here"); 346 break; 347 case Bytecodes::_athrow: 348 case Bytecodes::_ireturn: 349 case Bytecodes::_lreturn: 350 case Bytecodes::_freturn: 351 case Bytecodes::_dreturn: 352 case Bytecodes::_areturn: 353 case Bytecodes::_vreturn: 354 case Bytecodes::_return: 355 // These opcodes are not the normal predecessors of any other opcodes. 356 break; 357 case Bytecodes::_ret: 358 // We will patch up jsr/rets in a subsequent pass. 359 ret_list->append(current_block); 360 break; 361 case Bytecodes::_breakpoint: 362 // Bail out of there are breakpoints in here. 363 bailout = true; 364 break; 365 default: 366 // Do nothing. 367 break; 368 } 369 } 370 // Patch up the jsr/ret's. We conservatively assume that any ret 371 // can return to any jsr site. 372 int ret_list_len = ret_list->length(); 373 int jsr_exit_list_len = jsr_exit_list->length(); 374 if (ret_list_len > 0 && jsr_exit_list_len > 0) { 375 for (int i = jsr_exit_list_len - 1; i >= 0; i--) { 376 BasicBlock *jsrExit = jsr_exit_list->at(i); 377 for (int i = ret_list_len - 1; i >= 0; i--) { 378 jsrExit->add_normal_predecessor(ret_list->at(i)); 379 } 380 } 381 } 382 383 // Compute exception edges. 384 for (int b=_block_count-1; b >= 0; b--) { 385 BasicBlock *block = _block_list[b]; 386 int block_start = block->start_bci(); 387 int block_limit = block->limit_bci(); 388 ciExceptionHandlerStream handlers(method()); 389 for (; !handlers.is_done(); handlers.next()) { 390 ciExceptionHandler* handler = handlers.handler(); 391 int start = handler->start(); 392 int limit = handler->limit(); 393 int handler_bci = handler->handler_bci(); 394 395 int intersect_start = MAX2(block_start, start); 396 int intersect_limit = MIN2(block_limit, limit); 397 if (intersect_start < intersect_limit) { 398 // The catch range has a nonempty intersection with this 399 // basic block. That means this basic block can be an 400 // exceptional predecessor. 401 _block_map->at(handler_bci)->add_exception_predecessor(block); 402 403 if (handler->is_catch_all()) { 404 // This is a catch-all block. 405 if (intersect_start == block_start && intersect_limit == block_limit) { 406 // The basic block is entirely contained in this catch-all block. 407 // Skip the rest of the exception handlers -- they can never be 408 // reached in execution. 409 break; 410 } 411 } 412 } 413 } 414 } 415 } 416 417 void MethodLiveness::init_gen_kill() { 418 for (int i=_block_count-1; i >= 0; i--) { 419 _block_list[i]->compute_gen_kill(method()); 420 } 421 } 422 423 void MethodLiveness::propagate_liveness() { 424 int num_blocks = _block_count; 425 BasicBlock *block; 426 427 // We start our work list off with all blocks in it. 428 // Alternately, we could start off the work list with the list of all 429 // blocks which could exit the method directly, along with one block 430 // from any infinite loop. If this matters, it can be changed. It 431 // may not be clear from looking at the code, but the order of the 432 // workList will be the opposite of the creation order of the basic 433 // blocks, which should be decent for quick convergence (with the 434 // possible exception of exception handlers, which are all created 435 // early). 436 _work_list = NULL; 437 for (int i = 0; i < num_blocks; i++) { 438 block = _block_list[i]; 439 block->set_next(_work_list); 440 block->set_on_work_list(true); 441 _work_list = block; 442 } 443 444 445 while ((block = work_list_get()) != NULL) { 446 block->propagate(this); 447 NOT_PRODUCT(_total_visits++;) 448 } 449 } 450 451 void MethodLiveness::work_list_add(BasicBlock *block) { 452 if (!block->on_work_list()) { 453 block->set_next(_work_list); 454 block->set_on_work_list(true); 455 _work_list = block; 456 } 457 } 458 459 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() { 460 BasicBlock *block = _work_list; 461 if (block != NULL) { 462 block->set_on_work_list(false); 463 _work_list = block->next(); 464 } 465 return block; 466 } 467 468 469 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) { 470 int bci = entry_bci; 471 bool is_entry = false; 472 if (entry_bci == InvocationEntryBci) { 473 is_entry = true; 474 bci = 0; 475 } 476 477 MethodLivenessResult answer((BitMap::bm_word_t*)NULL,0); 478 479 if (_block_count > 0) { 480 if (TimeLivenessAnalysis) _time_total.start(); 481 if (TimeLivenessAnalysis) _time_query.start(); 482 483 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" ); 484 BasicBlock *block = _block_map->at(bci); 485 // We may not be at the block start, so search backwards to find the block 486 // containing bci. 487 int t = bci; 488 while (block == NULL && t > 0) { 489 block = _block_map->at(--t); 490 } 491 assert( block != NULL, "invalid bytecode index; must be instruction index" ); 492 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci."); 493 494 answer = block->get_liveness_at(method(), bci); 495 496 if (is_entry && method()->is_synchronized() && !method()->is_static()) { 497 // Synchronized methods use the receiver once on entry. 498 answer.at_put(0, true); 499 } 500 501 #ifndef PRODUCT 502 if (TraceLivenessQuery) { 503 tty->print("Liveness query of "); 504 method()->print_short_name(); 505 tty->print(" @ %d : result is ", bci); 506 answer.print_on(tty); 507 } 508 509 if (TimeLivenessAnalysis) _time_query.stop(); 510 if (TimeLivenessAnalysis) _time_total.stop(); 511 #endif 512 } 513 514 #ifndef PRODUCT 515 if (TimeLivenessAnalysis) { 516 // Collect statistics. 517 _total_locals_queried += _bit_map_size_bits; 518 BitCounter counter; 519 answer.iterate(&counter); 520 _total_live_locals_queried += counter.count(); 521 } 522 #endif 523 524 return answer; 525 } 526 527 528 #ifndef PRODUCT 529 530 void MethodLiveness::print_times() { 531 tty->print_cr ("Accumulated liveness analysis times/statistics:"); 532 tty->print_cr ("-----------------------------------------------"); 533 tty->print_cr (" Total : %3.3f sec.", _time_total.seconds()); 534 tty->print_cr (" Build graph : %3.3f sec. (%2.2f%%)", _time_build_graph.seconds(), 535 _time_build_graph.seconds() * 100 / _time_total.seconds()); 536 tty->print_cr (" Gen / Kill : %3.3f sec. (%2.2f%%)", _time_gen_kill.seconds(), 537 _time_gen_kill.seconds() * 100 / _time_total.seconds()); 538 tty->print_cr (" Dataflow : %3.3f sec. (%2.2f%%)", _time_flow.seconds(), 539 _time_flow.seconds() * 100 / _time_total.seconds()); 540 tty->print_cr (" Query : %3.3f sec. (%2.2f%%)", _time_query.seconds(), 541 _time_query.seconds() * 100 / _time_total.seconds()); 542 tty->print_cr (" #bytes : %8ld (%3.0f bytes per sec)", 543 _total_bytes, 544 _total_bytes / _time_total.seconds()); 545 tty->print_cr (" #methods : %8d (%3.0f methods per sec)", 546 _total_methods, 547 _total_methods / _time_total.seconds()); 548 tty->print_cr (" avg locals : %3.3f max locals : %3d", 549 (float)_total_method_locals / _total_methods, 550 _max_method_locals); 551 tty->print_cr (" avg blocks : %3.3f max blocks : %3d", 552 (float)_total_blocks / _total_methods, 553 _max_method_blocks); 554 tty->print_cr (" avg bytes : %3.3f", 555 (float)_total_bytes / _total_methods); 556 tty->print_cr (" #blocks : %8ld", 557 _total_blocks); 558 tty->print_cr (" avg normal predecessors : %3.3f max normal predecessors : %3d", 559 (float)_total_edges / _total_blocks, 560 _max_block_edges); 561 tty->print_cr (" avg exception predecessors : %3.3f max exception predecessors : %3d", 562 (float)_total_exc_edges / _total_blocks, 563 _max_block_exc_edges); 564 tty->print_cr (" avg visits : %3.3f", 565 (float)_total_visits / _total_blocks); 566 tty->print_cr (" #locals queried : %8ld #live : %8ld %%live : %2.2f%%", 567 _total_locals_queried, 568 _total_live_locals_queried, 569 100.0 * _total_live_locals_queried / _total_locals_queried); 570 } 571 572 #endif 573 574 575 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) : 576 _gen((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 577 analyzer->bit_map_size_bits()), 578 _kill((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 579 analyzer->bit_map_size_bits()), 580 _entry((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 581 analyzer->bit_map_size_bits()), 582 _normal_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 583 analyzer->bit_map_size_bits()), 584 _exception_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 585 analyzer->bit_map_size_bits()), 586 _last_bci(-1) { 587 _analyzer = analyzer; 588 _start_bci = start; 589 _limit_bci = limit; 590 _normal_predecessors = 591 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 592 _exception_predecessors = 593 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 594 _normal_exit.clear(); 595 _exception_exit.clear(); 596 _entry.clear(); 597 598 // this initialization is not strictly necessary. 599 // _gen and _kill are cleared at the beginning of compute_gen_kill_range() 600 _gen.clear(); 601 _kill.clear(); 602 } 603 604 605 606 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) { 607 int start = _start_bci; 608 int limit = _limit_bci; 609 610 if (TraceLivenessGen) { 611 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci); 612 } 613 614 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors; 615 616 assert (start < split_bci && split_bci < limit, "improper split"); 617 618 // Make a new block to cover the first half of the range. 619 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci); 620 621 // Assign correct values to the second half (this) 622 _normal_predecessors = first_half->_normal_predecessors; 623 _start_bci = split_bci; 624 add_normal_predecessor(first_half); 625 626 // Assign correct predecessors to the new first half 627 first_half->_normal_predecessors = save_predecessors; 628 629 return first_half; 630 } 631 632 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) { 633 ciBytecodeStream bytes(method); 634 bytes.reset_to_bci(start_bci()); 635 bytes.set_max_bci(limit_bci()); 636 compute_gen_kill_range(&bytes); 637 638 } 639 640 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) { 641 _gen.clear(); 642 _kill.clear(); 643 644 while (bytes->next() != ciBytecodeStream::EOBC()) { 645 compute_gen_kill_single(bytes); 646 } 647 } 648 649 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) { 650 int localNum; 651 652 // We prohibit _gen and _kill from having locals in common. If we 653 // know that one is definitely going to be applied before the other, 654 // we could save some computation time by relaxing this prohibition. 655 656 switch (instruction->cur_bc()) { 657 case Bytecodes::_nop: 658 case Bytecodes::_goto: 659 case Bytecodes::_goto_w: 660 case Bytecodes::_aconst_null: 661 case Bytecodes::_new: 662 case Bytecodes::_vnew: 663 case Bytecodes::_iconst_m1: 664 case Bytecodes::_iconst_0: 665 case Bytecodes::_iconst_1: 666 case Bytecodes::_iconst_2: 667 case Bytecodes::_iconst_3: 668 case Bytecodes::_iconst_4: 669 case Bytecodes::_iconst_5: 670 case Bytecodes::_fconst_0: 671 case Bytecodes::_fconst_1: 672 case Bytecodes::_fconst_2: 673 case Bytecodes::_bipush: 674 case Bytecodes::_sipush: 675 case Bytecodes::_lconst_0: 676 case Bytecodes::_lconst_1: 677 case Bytecodes::_dconst_0: 678 case Bytecodes::_dconst_1: 679 case Bytecodes::_ldc2_w: 680 case Bytecodes::_ldc: 681 case Bytecodes::_ldc_w: 682 case Bytecodes::_iaload: 683 case Bytecodes::_faload: 684 case Bytecodes::_baload: 685 case Bytecodes::_caload: 686 case Bytecodes::_saload: 687 case Bytecodes::_laload: 688 case Bytecodes::_daload: 689 case Bytecodes::_aaload: 690 case Bytecodes::_iastore: 691 case Bytecodes::_fastore: 692 case Bytecodes::_bastore: 693 case Bytecodes::_castore: 694 case Bytecodes::_sastore: 695 case Bytecodes::_lastore: 696 case Bytecodes::_dastore: 697 case Bytecodes::_aastore: 698 case Bytecodes::_pop: 699 case Bytecodes::_pop2: 700 case Bytecodes::_dup: 701 case Bytecodes::_dup_x1: 702 case Bytecodes::_dup_x2: 703 case Bytecodes::_dup2: 704 case Bytecodes::_dup2_x1: 705 case Bytecodes::_dup2_x2: 706 case Bytecodes::_swap: 707 case Bytecodes::_iadd: 708 case Bytecodes::_fadd: 709 case Bytecodes::_isub: 710 case Bytecodes::_fsub: 711 case Bytecodes::_imul: 712 case Bytecodes::_fmul: 713 case Bytecodes::_idiv: 714 case Bytecodes::_fdiv: 715 case Bytecodes::_irem: 716 case Bytecodes::_frem: 717 case Bytecodes::_ishl: 718 case Bytecodes::_ishr: 719 case Bytecodes::_iushr: 720 case Bytecodes::_iand: 721 case Bytecodes::_ior: 722 case Bytecodes::_ixor: 723 case Bytecodes::_l2f: 724 case Bytecodes::_l2i: 725 case Bytecodes::_d2f: 726 case Bytecodes::_d2i: 727 case Bytecodes::_fcmpl: 728 case Bytecodes::_fcmpg: 729 case Bytecodes::_ladd: 730 case Bytecodes::_dadd: 731 case Bytecodes::_lsub: 732 case Bytecodes::_dsub: 733 case Bytecodes::_lmul: 734 case Bytecodes::_dmul: 735 case Bytecodes::_ldiv: 736 case Bytecodes::_ddiv: 737 case Bytecodes::_lrem: 738 case Bytecodes::_drem: 739 case Bytecodes::_land: 740 case Bytecodes::_lor: 741 case Bytecodes::_lxor: 742 case Bytecodes::_ineg: 743 case Bytecodes::_fneg: 744 case Bytecodes::_i2f: 745 case Bytecodes::_f2i: 746 case Bytecodes::_i2c: 747 case Bytecodes::_i2s: 748 case Bytecodes::_i2b: 749 case Bytecodes::_lneg: 750 case Bytecodes::_dneg: 751 case Bytecodes::_l2d: 752 case Bytecodes::_d2l: 753 case Bytecodes::_lshl: 754 case Bytecodes::_lshr: 755 case Bytecodes::_lushr: 756 case Bytecodes::_i2l: 757 case Bytecodes::_i2d: 758 case Bytecodes::_f2l: 759 case Bytecodes::_f2d: 760 case Bytecodes::_lcmp: 761 case Bytecodes::_dcmpl: 762 case Bytecodes::_dcmpg: 763 case Bytecodes::_ifeq: 764 case Bytecodes::_ifne: 765 case Bytecodes::_iflt: 766 case Bytecodes::_ifge: 767 case Bytecodes::_ifgt: 768 case Bytecodes::_ifle: 769 case Bytecodes::_tableswitch: 770 case Bytecodes::_ireturn: 771 case Bytecodes::_freturn: 772 case Bytecodes::_if_icmpeq: 773 case Bytecodes::_if_icmpne: 774 case Bytecodes::_if_icmplt: 775 case Bytecodes::_if_icmpge: 776 case Bytecodes::_if_icmpgt: 777 case Bytecodes::_if_icmple: 778 case Bytecodes::_lreturn: 779 case Bytecodes::_dreturn: 780 case Bytecodes::_if_acmpeq: 781 case Bytecodes::_if_acmpne: 782 case Bytecodes::_jsr: 783 case Bytecodes::_jsr_w: 784 case Bytecodes::_getstatic: 785 case Bytecodes::_putstatic: 786 case Bytecodes::_getfield: 787 case Bytecodes::_vgetfield: 788 case Bytecodes::_putfield: 789 case Bytecodes::_invokevirtual: 790 case Bytecodes::_invokedirect: 791 case Bytecodes::_invokespecial: 792 case Bytecodes::_invokestatic: 793 case Bytecodes::_invokeinterface: 794 case Bytecodes::_invokedynamic: 795 case Bytecodes::_newarray: 796 case Bytecodes::_anewarray: 797 case Bytecodes::_checkcast: 798 case Bytecodes::_arraylength: 799 case Bytecodes::_instanceof: 800 case Bytecodes::_athrow: 801 case Bytecodes::_areturn: 802 case Bytecodes::_vreturn: 803 case Bytecodes::_monitorenter: 804 case Bytecodes::_monitorexit: 805 case Bytecodes::_ifnull: 806 case Bytecodes::_ifnonnull: 807 case Bytecodes::_multianewarray: 808 case Bytecodes::_lookupswitch: 809 case Bytecodes::_vbox: 810 case Bytecodes::_vunbox: 811 // These bytecodes have no effect on the method's locals. 812 break; 813 814 case Bytecodes::_return: 815 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) { 816 // return from Object.init implicitly registers a finalizer 817 // for the receiver if needed, so keep it alive. 818 load_one(0); 819 } 820 break; 821 822 823 case Bytecodes::_lload: 824 case Bytecodes::_dload: 825 load_two(instruction->get_index()); 826 break; 827 828 case Bytecodes::_lload_0: 829 case Bytecodes::_dload_0: 830 load_two(0); 831 break; 832 833 case Bytecodes::_lload_1: 834 case Bytecodes::_dload_1: 835 load_two(1); 836 break; 837 838 case Bytecodes::_lload_2: 839 case Bytecodes::_dload_2: 840 load_two(2); 841 break; 842 843 case Bytecodes::_lload_3: 844 case Bytecodes::_dload_3: 845 load_two(3); 846 break; 847 848 case Bytecodes::_iload: 849 case Bytecodes::_iinc: 850 case Bytecodes::_fload: 851 case Bytecodes::_aload: 852 case Bytecodes::_vload: 853 case Bytecodes::_ret: 854 load_one(instruction->get_index()); 855 break; 856 857 case Bytecodes::_iload_0: 858 case Bytecodes::_fload_0: 859 case Bytecodes::_aload_0: 860 load_one(0); 861 break; 862 863 case Bytecodes::_iload_1: 864 case Bytecodes::_fload_1: 865 case Bytecodes::_aload_1: 866 load_one(1); 867 break; 868 869 case Bytecodes::_iload_2: 870 case Bytecodes::_fload_2: 871 case Bytecodes::_aload_2: 872 load_one(2); 873 break; 874 875 case Bytecodes::_iload_3: 876 case Bytecodes::_fload_3: 877 case Bytecodes::_aload_3: 878 load_one(3); 879 break; 880 881 case Bytecodes::_lstore: 882 case Bytecodes::_dstore: 883 store_two(localNum = instruction->get_index()); 884 break; 885 886 case Bytecodes::_lstore_0: 887 case Bytecodes::_dstore_0: 888 store_two(0); 889 break; 890 891 case Bytecodes::_lstore_1: 892 case Bytecodes::_dstore_1: 893 store_two(1); 894 break; 895 896 case Bytecodes::_lstore_2: 897 case Bytecodes::_dstore_2: 898 store_two(2); 899 break; 900 901 case Bytecodes::_lstore_3: 902 case Bytecodes::_dstore_3: 903 store_two(3); 904 break; 905 906 case Bytecodes::_istore: 907 case Bytecodes::_fstore: 908 case Bytecodes::_astore: 909 case Bytecodes::_vstore: 910 store_one(instruction->get_index()); 911 break; 912 913 case Bytecodes::_istore_0: 914 case Bytecodes::_fstore_0: 915 case Bytecodes::_astore_0: 916 store_one(0); 917 break; 918 919 case Bytecodes::_istore_1: 920 case Bytecodes::_fstore_1: 921 case Bytecodes::_astore_1: 922 store_one(1); 923 break; 924 925 case Bytecodes::_istore_2: 926 case Bytecodes::_fstore_2: 927 case Bytecodes::_astore_2: 928 store_one(2); 929 break; 930 931 case Bytecodes::_istore_3: 932 case Bytecodes::_fstore_3: 933 case Bytecodes::_astore_3: 934 store_one(3); 935 break; 936 937 case Bytecodes::_wide: 938 fatal("Iterator should skip this bytecode"); 939 break; 940 941 default: 942 tty->print("unexpected opcode: %d\n", instruction->cur_bc()); 943 ShouldNotReachHere(); 944 break; 945 } 946 } 947 948 void MethodLiveness::BasicBlock::load_two(int local) { 949 load_one(local); 950 load_one(local+1); 951 } 952 953 void MethodLiveness::BasicBlock::load_one(int local) { 954 if (!_kill.at(local)) { 955 _gen.at_put(local, true); 956 } 957 } 958 959 void MethodLiveness::BasicBlock::store_two(int local) { 960 store_one(local); 961 store_one(local+1); 962 } 963 964 void MethodLiveness::BasicBlock::store_one(int local) { 965 if (!_gen.at(local)) { 966 _kill.at_put(local, true); 967 } 968 } 969 970 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) { 971 // These set operations could be combined for efficiency if the 972 // performance of this analysis becomes an issue. 973 _entry.set_union(_normal_exit); 974 _entry.set_difference(_kill); 975 _entry.set_union(_gen); 976 977 // Note that we merge information from our exceptional successors 978 // just once, rather than at individual bytecodes. 979 _entry.set_union(_exception_exit); 980 981 if (TraceLivenessGen) { 982 tty->print_cr(" ** Visiting block at %d **", start_bci()); 983 print_on(tty); 984 } 985 986 int i; 987 for (i=_normal_predecessors->length()-1; i>=0; i--) { 988 BasicBlock *block = _normal_predecessors->at(i); 989 if (block->merge_normal(_entry)) { 990 ml->work_list_add(block); 991 } 992 } 993 for (i=_exception_predecessors->length()-1; i>=0; i--) { 994 BasicBlock *block = _exception_predecessors->at(i); 995 if (block->merge_exception(_entry)) { 996 ml->work_list_add(block); 997 } 998 } 999 } 1000 1001 bool MethodLiveness::BasicBlock::merge_normal(BitMap other) { 1002 return _normal_exit.set_union_with_result(other); 1003 } 1004 1005 bool MethodLiveness::BasicBlock::merge_exception(BitMap other) { 1006 return _exception_exit.set_union_with_result(other); 1007 } 1008 1009 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) { 1010 MethodLivenessResult answer(NEW_RESOURCE_ARRAY(BitMap::bm_word_t, _analyzer->bit_map_size_words()), 1011 _analyzer->bit_map_size_bits()); 1012 answer.set_is_valid(); 1013 1014 #ifndef ASSERT 1015 if (bci == start_bci()) { 1016 answer.set_from(_entry); 1017 return answer; 1018 } 1019 #endif 1020 1021 #ifdef ASSERT 1022 ResourceMark rm; 1023 BitMap g(_gen.size()); g.set_from(_gen); 1024 BitMap k(_kill.size()); k.set_from(_kill); 1025 #endif 1026 if (_last_bci != bci || trueInDebug) { 1027 ciBytecodeStream bytes(method); 1028 bytes.reset_to_bci(bci); 1029 bytes.set_max_bci(limit_bci()); 1030 compute_gen_kill_range(&bytes); 1031 assert(_last_bci != bci || 1032 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect"); 1033 _last_bci = bci; 1034 } 1035 1036 answer.clear(); 1037 answer.set_union(_normal_exit); 1038 answer.set_difference(_kill); 1039 answer.set_union(_gen); 1040 answer.set_union(_exception_exit); 1041 1042 #ifdef ASSERT 1043 if (bci == start_bci()) { 1044 assert(answer.is_same(_entry), "optimized answer must be accurate"); 1045 } 1046 #endif 1047 1048 return answer; 1049 } 1050 1051 #ifndef PRODUCT 1052 1053 void MethodLiveness::BasicBlock::print_on(outputStream *os) const { 1054 os->print_cr("==================================================================="); 1055 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci); 1056 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length()); 1057 int i; 1058 for (i=0; i < _normal_predecessors->length(); i++) { 1059 os->print(" %4d", _normal_predecessors->at(i)->start_bci()); 1060 } 1061 os->cr(); 1062 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length()); 1063 for (i=0; i < _exception_predecessors->length(); i++) { 1064 os->print(" %4d", _exception_predecessors->at(i)->start_bci()); 1065 } 1066 os->cr(); 1067 os->print (" Normal Exit : "); 1068 _normal_exit.print_on(os); 1069 os->print (" Gen : "); 1070 _gen.print_on(os); 1071 os->print (" Kill : "); 1072 _kill.print_on(os); 1073 os->print (" Exception Exit: "); 1074 _exception_exit.print_on(os); 1075 os->print (" Entry : "); 1076 _entry.print_on(os); 1077 } 1078 1079 #endif // PRODUCT