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 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 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((uintptr_t*)arena->Amalloc((method->code_size() >> LogBitsPerByte) + 1), method->code_size()) 135 #endif 136 { 137 _arena = arena; 138 _method = method; 139 _bit_map_size_bits = method->max_locals(); 140 _bit_map_size_words = (_bit_map_size_bits / sizeof(unsigned int)) + 1; 141 142 #ifdef COMPILER1 143 _bci_block_start.clear(); 144 #endif 145 } 146 147 void MethodLiveness::compute_liveness() { 148 #ifndef PRODUCT 149 if (TraceLivenessGen) { 150 tty->print_cr("################################################################"); 151 tty->print("# Computing liveness information for "); 152 method()->print_short_name(); 153 } 154 155 if (TimeLivenessAnalysis) _time_total.start(); 156 #endif 157 158 { 159 TraceTime buildGraph(NULL, &_time_build_graph, TimeLivenessAnalysis); 160 init_basic_blocks(); 161 } 162 { 163 TraceTime genKill(NULL, &_time_gen_kill, TimeLivenessAnalysis); 164 init_gen_kill(); 165 } 166 { 167 TraceTime flow(NULL, &_time_flow, TimeLivenessAnalysis); 168 propagate_liveness(); 169 } 170 171 #ifndef PRODUCT 172 if (TimeLivenessAnalysis) _time_total.stop(); 173 174 if (TimeLivenessAnalysis) { 175 // Collect statistics 176 _total_bytes += method()->code_size(); 177 _total_methods++; 178 179 int num_blocks = _block_count; 180 _total_blocks += num_blocks; 181 _max_method_blocks = MAX2(num_blocks,_max_method_blocks); 182 183 for (int i=0; i<num_blocks; i++) { 184 BasicBlock *block = _block_list[i]; 185 186 int numEdges = block->_normal_predecessors->length(); 187 int numExcEdges = block->_exception_predecessors->length(); 188 189 _total_edges += numEdges; 190 _total_exc_edges += numExcEdges; 191 _max_block_edges = MAX2(numEdges,_max_block_edges); 192 _max_block_exc_edges = MAX2(numExcEdges,_max_block_exc_edges); 193 } 194 195 int numLocals = _bit_map_size_bits; 196 _total_method_locals += numLocals; 197 _max_method_locals = MAX2(numLocals,_max_method_locals); 198 } 199 #endif 200 } 201 202 203 void MethodLiveness::init_basic_blocks() { 204 bool bailout = false; 205 206 int method_len = method()->code_size(); 207 ciMethodBlocks *mblocks = method()->get_method_blocks(); 208 209 // Create an array to store the bci->BasicBlock mapping. 210 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL); 211 212 _block_count = mblocks->num_blocks(); 213 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count); 214 215 // Used for patching up jsr/ret control flow. 216 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5); 217 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5); 218 219 // generate our block list from ciMethodBlocks 220 for (int blk = 0; blk < _block_count; blk++) { 221 ciBlock *cib = mblocks->block(blk); 222 int start_bci = cib->start_bci(); 223 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci()); 224 _block_map->at_put(start_bci, _block_list[blk]); 225 #ifdef COMPILER1 226 // mark all bcis where a new basic block starts 227 _bci_block_start.set_bit(start_bci); 228 #endif // COMPILER1 229 } 230 // fill in the predecessors of blocks 231 ciBytecodeStream bytes(method()); 232 233 for (int blk = 0; blk < _block_count; blk++) { 234 BasicBlock *current_block = _block_list[blk]; 235 int bci = mblocks->block(blk)->control_bci(); 236 237 if (bci == ciBlock::fall_through_bci) { 238 int limit = current_block->limit_bci(); 239 if (limit < method_len) { 240 BasicBlock *next = _block_map->at(limit); 241 assert( next != NULL, "must be a block immediately following this one."); 242 next->add_normal_predecessor(current_block); 243 } 244 continue; 245 } 246 bytes.reset_to_bci(bci); 247 Bytecodes::Code code = bytes.next(); 248 BasicBlock *dest; 249 250 // Now we need to interpret the instruction's effect 251 // on control flow. 252 assert (current_block != NULL, "we must have a current block"); 253 switch (code) { 254 case Bytecodes::_ifeq: 255 case Bytecodes::_ifne: 256 case Bytecodes::_iflt: 257 case Bytecodes::_ifge: 258 case Bytecodes::_ifgt: 259 case Bytecodes::_ifle: 260 case Bytecodes::_if_icmpeq: 261 case Bytecodes::_if_icmpne: 262 case Bytecodes::_if_icmplt: 263 case Bytecodes::_if_icmpge: 264 case Bytecodes::_if_icmpgt: 265 case Bytecodes::_if_icmple: 266 case Bytecodes::_if_acmpeq: 267 case Bytecodes::_if_acmpne: 268 case Bytecodes::_ifnull: 269 case Bytecodes::_ifnonnull: 270 // Two way branch. Set predecessors at each destination. 271 dest = _block_map->at(bytes.next_bci()); 272 assert(dest != NULL, "must be a block immediately following this one."); 273 dest->add_normal_predecessor(current_block); 274 275 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: 280 dest = _block_map->at(bytes.get_dest()); 281 assert(dest != NULL, "branch desination must start a block."); 282 dest->add_normal_predecessor(current_block); 283 break; 284 case Bytecodes::_goto_w: 285 dest = _block_map->at(bytes.get_far_dest()); 286 assert(dest != NULL, "branch desination must start a block."); 287 dest->add_normal_predecessor(current_block); 288 break; 289 case Bytecodes::_tableswitch: 290 { 291 Bytecode_tableswitch tableswitch(&bytes); 292 293 int len = tableswitch.length(); 294 295 dest = _block_map->at(bci + tableswitch.default_offset()); 296 assert(dest != NULL, "branch desination must start a block."); 297 dest->add_normal_predecessor(current_block); 298 while (--len >= 0) { 299 dest = _block_map->at(bci + tableswitch.dest_offset_at(len)); 300 assert(dest != NULL, "branch desination must start a block."); 301 dest->add_normal_predecessor(current_block); 302 } 303 break; 304 } 305 306 case Bytecodes::_lookupswitch: 307 { 308 Bytecode_lookupswitch lookupswitch(&bytes); 309 310 int npairs = lookupswitch.number_of_pairs(); 311 312 dest = _block_map->at(bci + lookupswitch.default_offset()); 313 assert(dest != NULL, "branch desination must start a block."); 314 dest->add_normal_predecessor(current_block); 315 while(--npairs >= 0) { 316 LookupswitchPair pair = lookupswitch.pair_at(npairs); 317 dest = _block_map->at( bci + pair.offset()); 318 assert(dest != NULL, "branch desination must start a block."); 319 dest->add_normal_predecessor(current_block); 320 } 321 break; 322 } 323 324 case Bytecodes::_jsr: 325 { 326 assert(bytes.is_wide()==false, "sanity check"); 327 dest = _block_map->at(bytes.get_dest()); 328 assert(dest != NULL, "branch desination must start a block."); 329 dest->add_normal_predecessor(current_block); 330 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 331 assert(jsrExit != NULL, "jsr return bci must start a block."); 332 jsr_exit_list->append(jsrExit); 333 break; 334 } 335 case Bytecodes::_jsr_w: 336 { 337 dest = _block_map->at(bytes.get_far_dest()); 338 assert(dest != NULL, "branch desination must start a block."); 339 dest->add_normal_predecessor(current_block); 340 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 341 assert(jsrExit != NULL, "jsr return bci must start a block."); 342 jsr_exit_list->append(jsrExit); 343 break; 344 } 345 346 case Bytecodes::_wide: 347 assert(false, "wide opcodes should not be seen here"); 348 break; 349 case Bytecodes::_athrow: 350 case Bytecodes::_ireturn: 351 case Bytecodes::_lreturn: 352 case Bytecodes::_freturn: 353 case Bytecodes::_dreturn: 354 case Bytecodes::_areturn: 355 case Bytecodes::_return: 356 // These opcodes are not the normal predecessors of any other opcodes. 357 break; 358 case Bytecodes::_ret: 359 // We will patch up jsr/rets in a subsequent pass. 360 ret_list->append(current_block); 361 break; 362 case Bytecodes::_breakpoint: 363 // Bail out of there are breakpoints in here. 364 bailout = true; 365 break; 366 default: 367 // Do nothing. 368 break; 369 } 370 } 371 // Patch up the jsr/ret's. We conservatively assume that any ret 372 // can return to any jsr site. 373 int ret_list_len = ret_list->length(); 374 int jsr_exit_list_len = jsr_exit_list->length(); 375 if (ret_list_len > 0 && jsr_exit_list_len > 0) { 376 for (int i = jsr_exit_list_len - 1; i >= 0; i--) { 377 BasicBlock *jsrExit = jsr_exit_list->at(i); 378 for (int i = ret_list_len - 1; i >= 0; i--) { 379 jsrExit->add_normal_predecessor(ret_list->at(i)); 380 } 381 } 382 } 383 384 // Compute exception edges. 385 for (int b=_block_count-1; b >= 0; b--) { 386 BasicBlock *block = _block_list[b]; 387 int block_start = block->start_bci(); 388 int block_limit = block->limit_bci(); 389 ciExceptionHandlerStream handlers(method()); 390 for (; !handlers.is_done(); handlers.next()) { 391 ciExceptionHandler* handler = handlers.handler(); 392 int start = handler->start(); 393 int limit = handler->limit(); 394 int handler_bci = handler->handler_bci(); 395 396 int intersect_start = MAX2(block_start, start); 397 int intersect_limit = MIN2(block_limit, limit); 398 if (intersect_start < intersect_limit) { 399 // The catch range has a nonempty intersection with this 400 // basic block. That means this basic block can be an 401 // exceptional predecessor. 402 _block_map->at(handler_bci)->add_exception_predecessor(block); 403 404 if (handler->is_catch_all()) { 405 // This is a catch-all block. 406 if (intersect_start == block_start && intersect_limit == block_limit) { 407 // The basic block is entirely contained in this catch-all block. 408 // Skip the rest of the exception handlers -- they can never be 409 // reached in execution. 410 break; 411 } 412 } 413 } 414 } 415 } 416 } 417 418 void MethodLiveness::init_gen_kill() { 419 for (int i=_block_count-1; i >= 0; i--) { 420 _block_list[i]->compute_gen_kill(method()); 421 } 422 } 423 424 void MethodLiveness::propagate_liveness() { 425 int num_blocks = _block_count; 426 BasicBlock *block; 427 428 // We start our work list off with all blocks in it. 429 // Alternately, we could start off the work list with the list of all 430 // blocks which could exit the method directly, along with one block 431 // from any infinite loop. If this matters, it can be changed. It 432 // may not be clear from looking at the code, but the order of the 433 // workList will be the opposite of the creation order of the basic 434 // blocks, which should be decent for quick convergence (with the 435 // possible exception of exception handlers, which are all created 436 // early). 437 _work_list = NULL; 438 for (int i = 0; i < num_blocks; i++) { 439 block = _block_list[i]; 440 block->set_next(_work_list); 441 block->set_on_work_list(true); 442 _work_list = block; 443 } 444 445 446 while ((block = work_list_get()) != NULL) { 447 block->propagate(this); 448 NOT_PRODUCT(_total_visits++;) 449 } 450 } 451 452 void MethodLiveness::work_list_add(BasicBlock *block) { 453 if (!block->on_work_list()) { 454 block->set_next(_work_list); 455 block->set_on_work_list(true); 456 _work_list = block; 457 } 458 } 459 460 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() { 461 BasicBlock *block = _work_list; 462 if (block != NULL) { 463 block->set_on_work_list(false); 464 _work_list = block->next(); 465 } 466 return block; 467 } 468 469 470 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) { 471 int bci = entry_bci; 472 bool is_entry = false; 473 if (entry_bci == InvocationEntryBci) { 474 is_entry = true; 475 bci = 0; 476 } 477 478 MethodLivenessResult answer((BitMap::bm_word_t*)NULL,0); 479 480 if (_block_count > 0) { 481 if (TimeLivenessAnalysis) _time_total.start(); 482 if (TimeLivenessAnalysis) _time_query.start(); 483 484 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" ); 485 BasicBlock *block = _block_map->at(bci); 486 // We may not be at the block start, so search backwards to find the block 487 // containing bci. 488 int t = bci; 489 while (block == NULL && t > 0) { 490 block = _block_map->at(--t); 491 } 492 assert( block != NULL, "invalid bytecode index; must be instruction index" ); 493 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci."); 494 495 answer = block->get_liveness_at(method(), bci); 496 497 if (is_entry && method()->is_synchronized() && !method()->is_static()) { 498 // Synchronized methods use the receiver once on entry. 499 answer.at_put(0, true); 500 } 501 502 #ifndef PRODUCT 503 if (TraceLivenessQuery) { 504 tty->print("Liveness query of "); 505 method()->print_short_name(); 506 tty->print(" @ %d : result is ", bci); 507 answer.print_on(tty); 508 } 509 510 if (TimeLivenessAnalysis) _time_query.stop(); 511 if (TimeLivenessAnalysis) _time_total.stop(); 512 #endif 513 } 514 515 #ifndef PRODUCT 516 if (TimeLivenessAnalysis) { 517 // Collect statistics. 518 _total_locals_queried += _bit_map_size_bits; 519 BitCounter counter; 520 answer.iterate(&counter); 521 _total_live_locals_queried += counter.count(); 522 } 523 #endif 524 525 return answer; 526 } 527 528 529 #ifndef PRODUCT 530 531 void MethodLiveness::print_times() { 532 tty->print_cr ("Accumulated liveness analysis times/statistics:"); 533 tty->print_cr ("-----------------------------------------------"); 534 tty->print_cr (" Total : %3.3f sec.", _time_total.seconds()); 535 tty->print_cr (" Build graph : %3.3f sec. (%2.2f%%)", _time_build_graph.seconds(), 536 _time_build_graph.seconds() * 100 / _time_total.seconds()); 537 tty->print_cr (" Gen / Kill : %3.3f sec. (%2.2f%%)", _time_gen_kill.seconds(), 538 _time_gen_kill.seconds() * 100 / _time_total.seconds()); 539 tty->print_cr (" Dataflow : %3.3f sec. (%2.2f%%)", _time_flow.seconds(), 540 _time_flow.seconds() * 100 / _time_total.seconds()); 541 tty->print_cr (" Query : %3.3f sec. (%2.2f%%)", _time_query.seconds(), 542 _time_query.seconds() * 100 / _time_total.seconds()); 543 tty->print_cr (" #bytes : %8d (%3.0f bytes per sec)", 544 _total_bytes, 545 _total_bytes / _time_total.seconds()); 546 tty->print_cr (" #methods : %8d (%3.0f methods per sec)", 547 _total_methods, 548 _total_methods / _time_total.seconds()); 549 tty->print_cr (" avg locals : %3.3f max locals : %3d", 550 (float)_total_method_locals / _total_methods, 551 _max_method_locals); 552 tty->print_cr (" avg blocks : %3.3f max blocks : %3d", 553 (float)_total_blocks / _total_methods, 554 _max_method_blocks); 555 tty->print_cr (" avg bytes : %3.3f", 556 (float)_total_bytes / _total_methods); 557 tty->print_cr (" #blocks : %8d", 558 _total_blocks); 559 tty->print_cr (" avg normal predecessors : %3.3f max normal predecessors : %3d", 560 (float)_total_edges / _total_blocks, 561 _max_block_edges); 562 tty->print_cr (" avg exception predecessors : %3.3f max exception predecessors : %3d", 563 (float)_total_exc_edges / _total_blocks, 564 _max_block_exc_edges); 565 tty->print_cr (" avg visits : %3.3f", 566 (float)_total_visits / _total_blocks); 567 tty->print_cr (" #locals queried : %8d #live : %8d %%live : %2.2f%%", 568 _total_locals_queried, 569 _total_live_locals_queried, 570 100.0 * _total_live_locals_queried / _total_locals_queried); 571 } 572 573 #endif 574 575 576 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) : 577 _gen((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 578 analyzer->bit_map_size_bits()), 579 _kill((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 580 analyzer->bit_map_size_bits()), 581 _entry((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 582 analyzer->bit_map_size_bits()), 583 _normal_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 584 analyzer->bit_map_size_bits()), 585 _exception_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()), 586 analyzer->bit_map_size_bits()), 587 _last_bci(-1) { 588 _analyzer = analyzer; 589 _start_bci = start; 590 _limit_bci = limit; 591 _normal_predecessors = 592 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 593 _exception_predecessors = 594 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 595 _normal_exit.clear(); 596 _exception_exit.clear(); 597 _entry.clear(); 598 599 // this initialization is not strictly necessary. 600 // _gen and _kill are cleared at the beginning of compute_gen_kill_range() 601 _gen.clear(); 602 _kill.clear(); 603 } 604 605 606 607 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) { 608 int start = _start_bci; 609 int limit = _limit_bci; 610 611 if (TraceLivenessGen) { 612 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci); 613 } 614 615 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors; 616 617 assert (start < split_bci && split_bci < limit, "improper split"); 618 619 // Make a new block to cover the first half of the range. 620 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci); 621 622 // Assign correct values to the second half (this) 623 _normal_predecessors = first_half->_normal_predecessors; 624 _start_bci = split_bci; 625 add_normal_predecessor(first_half); 626 627 // Assign correct predecessors to the new first half 628 first_half->_normal_predecessors = save_predecessors; 629 630 return first_half; 631 } 632 633 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) { 634 ciBytecodeStream bytes(method); 635 bytes.reset_to_bci(start_bci()); 636 bytes.set_max_bci(limit_bci()); 637 compute_gen_kill_range(&bytes); 638 639 } 640 641 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) { 642 _gen.clear(); 643 _kill.clear(); 644 645 while (bytes->next() != ciBytecodeStream::EOBC()) { 646 compute_gen_kill_single(bytes); 647 } 648 } 649 650 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) { 651 int localNum; 652 653 // We prohibit _gen and _kill from having locals in common. If we 654 // know that one is definitely going to be applied before the other, 655 // we could save some computation time by relaxing this prohibition. 656 657 switch (instruction->cur_bc()) { 658 case Bytecodes::_nop: 659 case Bytecodes::_goto: 660 case Bytecodes::_goto_w: 661 case Bytecodes::_aconst_null: 662 case Bytecodes::_new: 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::_putfield: 788 case Bytecodes::_invokevirtual: 789 case Bytecodes::_invokespecial: 790 case Bytecodes::_invokestatic: 791 case Bytecodes::_invokeinterface: 792 case Bytecodes::_invokedynamic: 793 case Bytecodes::_newarray: 794 case Bytecodes::_anewarray: 795 case Bytecodes::_checkcast: 796 case Bytecodes::_arraylength: 797 case Bytecodes::_instanceof: 798 case Bytecodes::_athrow: 799 case Bytecodes::_areturn: 800 case Bytecodes::_monitorenter: 801 case Bytecodes::_monitorexit: 802 case Bytecodes::_ifnull: 803 case Bytecodes::_ifnonnull: 804 case Bytecodes::_multianewarray: 805 case Bytecodes::_lookupswitch: 806 // These bytecodes have no effect on the method's locals. 807 break; 808 809 case Bytecodes::_return: 810 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) { 811 // return from Object.init implicitly registers a finalizer 812 // for the receiver if needed, so keep it alive. 813 load_one(0); 814 } 815 break; 816 817 818 case Bytecodes::_lload: 819 case Bytecodes::_dload: 820 load_two(instruction->get_index()); 821 break; 822 823 case Bytecodes::_lload_0: 824 case Bytecodes::_dload_0: 825 load_two(0); 826 break; 827 828 case Bytecodes::_lload_1: 829 case Bytecodes::_dload_1: 830 load_two(1); 831 break; 832 833 case Bytecodes::_lload_2: 834 case Bytecodes::_dload_2: 835 load_two(2); 836 break; 837 838 case Bytecodes::_lload_3: 839 case Bytecodes::_dload_3: 840 load_two(3); 841 break; 842 843 case Bytecodes::_iload: 844 case Bytecodes::_iinc: 845 case Bytecodes::_fload: 846 case Bytecodes::_aload: 847 case Bytecodes::_ret: 848 load_one(instruction->get_index()); 849 break; 850 851 case Bytecodes::_iload_0: 852 case Bytecodes::_fload_0: 853 case Bytecodes::_aload_0: 854 load_one(0); 855 break; 856 857 case Bytecodes::_iload_1: 858 case Bytecodes::_fload_1: 859 case Bytecodes::_aload_1: 860 load_one(1); 861 break; 862 863 case Bytecodes::_iload_2: 864 case Bytecodes::_fload_2: 865 case Bytecodes::_aload_2: 866 load_one(2); 867 break; 868 869 case Bytecodes::_iload_3: 870 case Bytecodes::_fload_3: 871 case Bytecodes::_aload_3: 872 load_one(3); 873 break; 874 875 case Bytecodes::_lstore: 876 case Bytecodes::_dstore: 877 store_two(localNum = instruction->get_index()); 878 break; 879 880 case Bytecodes::_lstore_0: 881 case Bytecodes::_dstore_0: 882 store_two(0); 883 break; 884 885 case Bytecodes::_lstore_1: 886 case Bytecodes::_dstore_1: 887 store_two(1); 888 break; 889 890 case Bytecodes::_lstore_2: 891 case Bytecodes::_dstore_2: 892 store_two(2); 893 break; 894 895 case Bytecodes::_lstore_3: 896 case Bytecodes::_dstore_3: 897 store_two(3); 898 break; 899 900 case Bytecodes::_istore: 901 case Bytecodes::_fstore: 902 case Bytecodes::_astore: 903 store_one(instruction->get_index()); 904 break; 905 906 case Bytecodes::_istore_0: 907 case Bytecodes::_fstore_0: 908 case Bytecodes::_astore_0: 909 store_one(0); 910 break; 911 912 case Bytecodes::_istore_1: 913 case Bytecodes::_fstore_1: 914 case Bytecodes::_astore_1: 915 store_one(1); 916 break; 917 918 case Bytecodes::_istore_2: 919 case Bytecodes::_fstore_2: 920 case Bytecodes::_astore_2: 921 store_one(2); 922 break; 923 924 case Bytecodes::_istore_3: 925 case Bytecodes::_fstore_3: 926 case Bytecodes::_astore_3: 927 store_one(3); 928 break; 929 930 case Bytecodes::_wide: 931 fatal("Iterator should skip this bytecode"); 932 break; 933 934 default: 935 tty->print("unexpected opcode: %d\n", instruction->cur_bc()); 936 ShouldNotReachHere(); 937 break; 938 } 939 } 940 941 void MethodLiveness::BasicBlock::load_two(int local) { 942 load_one(local); 943 load_one(local+1); 944 } 945 946 void MethodLiveness::BasicBlock::load_one(int local) { 947 if (!_kill.at(local)) { 948 _gen.at_put(local, true); 949 } 950 } 951 952 void MethodLiveness::BasicBlock::store_two(int local) { 953 store_one(local); 954 store_one(local+1); 955 } 956 957 void MethodLiveness::BasicBlock::store_one(int local) { 958 if (!_gen.at(local)) { 959 _kill.at_put(local, true); 960 } 961 } 962 963 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) { 964 // These set operations could be combined for efficiency if the 965 // performance of this analysis becomes an issue. 966 _entry.set_union(_normal_exit); 967 _entry.set_difference(_kill); 968 _entry.set_union(_gen); 969 970 // Note that we merge information from our exceptional successors 971 // just once, rather than at individual bytecodes. 972 _entry.set_union(_exception_exit); 973 974 if (TraceLivenessGen) { 975 tty->print_cr(" ** Visiting block at %d **", start_bci()); 976 print_on(tty); 977 } 978 979 int i; 980 for (i=_normal_predecessors->length()-1; i>=0; i--) { 981 BasicBlock *block = _normal_predecessors->at(i); 982 if (block->merge_normal(_entry)) { 983 ml->work_list_add(block); 984 } 985 } 986 for (i=_exception_predecessors->length()-1; i>=0; i--) { 987 BasicBlock *block = _exception_predecessors->at(i); 988 if (block->merge_exception(_entry)) { 989 ml->work_list_add(block); 990 } 991 } 992 } 993 994 bool MethodLiveness::BasicBlock::merge_normal(BitMap other) { 995 return _normal_exit.set_union_with_result(other); 996 } 997 998 bool MethodLiveness::BasicBlock::merge_exception(BitMap other) { 999 return _exception_exit.set_union_with_result(other); 1000 } 1001 1002 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) { 1003 MethodLivenessResult answer(NEW_RESOURCE_ARRAY(BitMap::bm_word_t, _analyzer->bit_map_size_words()), 1004 _analyzer->bit_map_size_bits()); 1005 answer.set_is_valid(); 1006 1007 #ifndef ASSERT 1008 if (bci == start_bci()) { 1009 answer.set_from(_entry); 1010 return answer; 1011 } 1012 #endif 1013 1014 #ifdef ASSERT 1015 ResourceMark rm; 1016 BitMap g(_gen.size()); g.set_from(_gen); 1017 BitMap k(_kill.size()); k.set_from(_kill); 1018 #endif 1019 if (_last_bci != bci || trueInDebug) { 1020 ciBytecodeStream bytes(method); 1021 bytes.reset_to_bci(bci); 1022 bytes.set_max_bci(limit_bci()); 1023 compute_gen_kill_range(&bytes); 1024 assert(_last_bci != bci || 1025 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect"); 1026 _last_bci = bci; 1027 } 1028 1029 answer.clear(); 1030 answer.set_union(_normal_exit); 1031 answer.set_difference(_kill); 1032 answer.set_union(_gen); 1033 answer.set_union(_exception_exit); 1034 1035 #ifdef ASSERT 1036 if (bci == start_bci()) { 1037 assert(answer.is_same(_entry), "optimized answer must be accurate"); 1038 } 1039 #endif 1040 1041 return answer; 1042 } 1043 1044 #ifndef PRODUCT 1045 1046 void MethodLiveness::BasicBlock::print_on(outputStream *os) const { 1047 os->print_cr("==================================================================="); 1048 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci); 1049 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length()); 1050 int i; 1051 for (i=0; i < _normal_predecessors->length(); i++) { 1052 os->print(" %4d", _normal_predecessors->at(i)->start_bci()); 1053 } 1054 os->cr(); 1055 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length()); 1056 for (i=0; i < _exception_predecessors->length(); i++) { 1057 os->print(" %4d", _exception_predecessors->at(i)->start_bci()); 1058 } 1059 os->cr(); 1060 os->print (" Normal Exit : "); 1061 _normal_exit.print_on(os); 1062 os->print (" Gen : "); 1063 _gen.print_on(os); 1064 os->print (" Kill : "); 1065 _kill.print_on(os); 1066 os->print (" Exception Exit: "); 1067 _exception_exit.print_on(os); 1068 os->print (" Entry : "); 1069 _entry.print_on(os); 1070 } 1071 1072 #endif // PRODUCT