1 /* 2 * Copyright (c) 1998, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "ci/ciMethod.hpp" 27 #include "ci/ciMethodBlocks.hpp" 28 #include "ci/ciStreams.hpp" 29 #include "compiler/methodLiveness.hpp" 30 #include "interpreter/bytecode.hpp" 31 #include "interpreter/bytecodes.hpp" 32 #include "memory/allocation.inline.hpp" 33 #include "memory/resourceArea.hpp" 34 #include "utilities/bitMap.inline.hpp" 35 36 // The MethodLiveness class performs a simple liveness analysis on a method 37 // in order to decide which locals are live (that is, will be used again) at 38 // a particular bytecode index (bci). 39 // 40 // The algorithm goes: 41 // 42 // 1. Break the method into a set of basic blocks. For each basic block we 43 // also keep track of its set of predecessors through normal control flow 44 // and predecessors through exceptional control flow. 45 // 46 // 2. For each basic block, compute two sets, gen (the set of values used before 47 // they are defined) and kill (the set of values defined before they are used) 48 // in the basic block. A basic block "needs" the locals in its gen set to 49 // perform its computation. A basic block "provides" values for the locals in 50 // its kill set, allowing a need from a successor to be ignored. 51 // 52 // 3. Liveness information (the set of locals which are needed) is pushed backwards through 53 // the program, from blocks to their predecessors. We compute and store liveness 54 // information for the normal/exceptional exit paths for each basic block. When 55 // this process reaches a fixed point, we are done. 56 // 57 // 4. When we are asked about the liveness at a particular bci with a basic block, we 58 // compute gen/kill sets which represent execution from that bci to the exit of 59 // its blocks. We then compose this range gen/kill information with the normal 60 // and exceptional exit information for the block to produce liveness information 61 // at that bci. 62 // 63 // The algorithm is approximate in many respects. Notably: 64 // 65 // 1. We do not do the analysis necessary to match jsr's with the appropriate ret. 66 // Instead we make the conservative assumption that any ret can return to any 67 // jsr return site. 68 // 2. Instead of computing the effects of exceptions at every instruction, we 69 // summarize the effects of all exceptional continuations from the block as 70 // a single set (_exception_exit), losing some information but simplifying the 71 // analysis. 72 73 74 //-------------------------------------------------------------------------- 75 // The BitCounter class is used for counting the number of bits set in 76 // some BitMap. It is only used when collecting liveness statistics. 77 78 #ifndef PRODUCT 79 80 class BitCounter: public BitMapClosure { 81 private: 82 int _count; 83 public: 84 BitCounter() : _count(0) {} 85 86 // Callback when bit in map is set 87 virtual bool do_bit(size_t offset) { 88 _count++; 89 return true; 90 } 91 92 int count() { 93 return _count; 94 } 95 }; 96 97 98 //-------------------------------------------------------------------------- 99 100 101 // Counts 102 long MethodLiveness::_total_bytes = 0; 103 int MethodLiveness::_total_methods = 0; 104 105 long MethodLiveness::_total_blocks = 0; 106 int MethodLiveness::_max_method_blocks = 0; 107 108 long MethodLiveness::_total_edges = 0; 109 int MethodLiveness::_max_block_edges = 0; 110 111 long MethodLiveness::_total_exc_edges = 0; 112 int MethodLiveness::_max_block_exc_edges = 0; 113 114 long MethodLiveness::_total_method_locals = 0; 115 int MethodLiveness::_max_method_locals = 0; 116 117 long MethodLiveness::_total_locals_queried = 0; 118 long MethodLiveness::_total_live_locals_queried = 0; 119 120 long MethodLiveness::_total_visits = 0; 121 122 #endif 123 124 // Timers 125 elapsedTimer MethodLiveness::_time_build_graph; 126 elapsedTimer MethodLiveness::_time_gen_kill; 127 elapsedTimer MethodLiveness::_time_flow; 128 elapsedTimer MethodLiveness::_time_query; 129 elapsedTimer MethodLiveness::_time_total; 130 131 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method) 132 #ifdef COMPILER1 133 : _bci_block_start((uintptr_t*)arena->Amalloc((method->code_size() >> LogBitsPerByte) + 1), method->code_size()) 134 #endif 135 { 136 _arena = arena; 137 _method = method; 138 _bit_map_size_bits = method->max_locals(); 139 _bit_map_size_words = (_bit_map_size_bits / sizeof(unsigned int)) + 1; 140 141 #ifdef COMPILER1 142 _bci_block_start.clear(); 143 #endif 144 } 145 146 void MethodLiveness::compute_liveness() { 147 #ifndef PRODUCT 148 if (TraceLivenessGen) { 149 tty->print_cr("################################################################"); 150 tty->print("# Computing liveness information for "); 151 method()->print_short_name(); 152 } 153 154 if (TimeLivenessAnalysis) _time_total.start(); 155 #endif 156 157 { 158 TraceTime buildGraph(NULL, &_time_build_graph, TimeLivenessAnalysis); 159 init_basic_blocks(); 160 } 161 { 162 TraceTime genKill(NULL, &_time_gen_kill, TimeLivenessAnalysis); 163 init_gen_kill(); 164 } 165 { 166 TraceTime flow(NULL, &_time_flow, TimeLivenessAnalysis); 167 propagate_liveness(); 168 } 169 170 #ifndef PRODUCT 171 if (TimeLivenessAnalysis) _time_total.stop(); 172 173 if (TimeLivenessAnalysis) { 174 // Collect statistics 175 _total_bytes += method()->code_size(); 176 _total_methods++; 177 178 int num_blocks = _block_count; 179 _total_blocks += num_blocks; 180 _max_method_blocks = MAX2(num_blocks,_max_method_blocks); 181 182 for (int i=0; i<num_blocks; i++) { 183 BasicBlock *block = _block_list[i]; 184 185 int numEdges = block->_normal_predecessors->length(); 186 int numExcEdges = block->_exception_predecessors->length(); 187 188 _total_edges += numEdges; 189 _total_exc_edges += numExcEdges; 190 _max_block_edges = MAX2(numEdges,_max_block_edges); 191 _max_block_exc_edges = MAX2(numExcEdges,_max_block_exc_edges); 192 } 193 194 int numLocals = _bit_map_size_bits; 195 _total_method_locals += numLocals; 196 _max_method_locals = MAX2(numLocals,_max_method_locals); 197 } 198 #endif 199 } 200 201 202 void MethodLiveness::init_basic_blocks() { 203 bool bailout = false; 204 205 int method_len = method()->code_size(); 206 ciMethodBlocks *mblocks = method()->get_method_blocks(); 207 208 // Create an array to store the bci->BasicBlock mapping. 209 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL); 210 211 _block_count = mblocks->num_blocks(); 212 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count); 213 214 // Used for patching up jsr/ret control flow. 215 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5); 216 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5); 217 218 // generate our block list from ciMethodBlocks 219 for (int blk = 0; blk < _block_count; blk++) { 220 ciBlock *cib = mblocks->block(blk); 221 int start_bci = cib->start_bci(); 222 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci()); 223 _block_map->at_put(start_bci, _block_list[blk]); 224 #ifdef COMPILER1 225 // mark all bcis where a new basic block starts 226 _bci_block_start.set_bit(start_bci); 227 #endif // COMPILER1 228 } 229 // fill in the predecessors of blocks 230 ciBytecodeStream bytes(method()); 231 232 for (int blk = 0; blk < _block_count; blk++) { 233 BasicBlock *current_block = _block_list[blk]; 234 int bci = mblocks->block(blk)->control_bci(); 235 236 if (bci == ciBlock::fall_through_bci) { 237 int limit = current_block->limit_bci(); 238 if (limit < method_len) { 239 BasicBlock *next = _block_map->at(limit); 240 assert( next != NULL, "must be a block immediately following this one."); 241 next->add_normal_predecessor(current_block); 242 } 243 continue; 244 } 245 bytes.reset_to_bci(bci); 246 Bytecodes::Code code = bytes.next(); 247 BasicBlock *dest; 248 249 // Now we need to interpret the instruction's effect 250 // on control flow. 251 assert (current_block != NULL, "we must have a current block"); 252 switch (code) { 253 case Bytecodes::_ifeq: 254 case Bytecodes::_ifne: 255 case Bytecodes::_iflt: 256 case Bytecodes::_ifge: 257 case Bytecodes::_ifgt: 258 case Bytecodes::_ifle: 259 case Bytecodes::_if_icmpeq: 260 case Bytecodes::_if_icmpne: 261 case Bytecodes::_if_icmplt: 262 case Bytecodes::_if_icmpge: 263 case Bytecodes::_if_icmpgt: 264 case Bytecodes::_if_icmple: 265 case Bytecodes::_if_acmpeq: 266 case Bytecodes::_if_acmpne: 267 case Bytecodes::_ifnull: 268 case Bytecodes::_ifnonnull: 269 // Two way branch. Set predecessors at each destination. 270 dest = _block_map->at(bytes.next_bci()); 271 assert(dest != NULL, "must be a block immediately following this one."); 272 dest->add_normal_predecessor(current_block); 273 274 dest = _block_map->at(bytes.get_dest()); 275 assert(dest != NULL, "branch desination must start a block."); 276 dest->add_normal_predecessor(current_block); 277 break; 278 case Bytecodes::_goto: 279 dest = _block_map->at(bytes.get_dest()); 280 assert(dest != NULL, "branch desination must start a block."); 281 dest->add_normal_predecessor(current_block); 282 break; 283 case Bytecodes::_goto_w: 284 dest = _block_map->at(bytes.get_far_dest()); 285 assert(dest != NULL, "branch desination must start a block."); 286 dest->add_normal_predecessor(current_block); 287 break; 288 case Bytecodes::_tableswitch: 289 { 290 Bytecode_tableswitch tableswitch(&bytes); 291 292 int len = tableswitch.length(); 293 294 dest = _block_map->at(bci + tableswitch.default_offset()); 295 assert(dest != NULL, "branch desination must start a block."); 296 dest->add_normal_predecessor(current_block); 297 while (--len >= 0) { 298 dest = _block_map->at(bci + tableswitch.dest_offset_at(len)); 299 assert(dest != NULL, "branch desination must start a block."); 300 dest->add_normal_predecessor(current_block); 301 } 302 break; 303 } 304 305 case Bytecodes::_lookupswitch: 306 { 307 Bytecode_lookupswitch lookupswitch(&bytes); 308 309 int npairs = lookupswitch.number_of_pairs(); 310 311 dest = _block_map->at(bci + lookupswitch.default_offset()); 312 assert(dest != NULL, "branch desination must start a block."); 313 dest->add_normal_predecessor(current_block); 314 while(--npairs >= 0) { 315 LookupswitchPair pair = lookupswitch.pair_at(npairs); 316 dest = _block_map->at( bci + pair.offset()); 317 assert(dest != NULL, "branch desination must start a block."); 318 dest->add_normal_predecessor(current_block); 319 } 320 break; 321 } 322 323 case Bytecodes::_jsr: 324 { 325 assert(bytes.is_wide()==false, "sanity check"); 326 dest = _block_map->at(bytes.get_dest()); 327 assert(dest != NULL, "branch desination must start a block."); 328 dest->add_normal_predecessor(current_block); 329 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 330 assert(jsrExit != NULL, "jsr return bci must start a block."); 331 jsr_exit_list->append(jsrExit); 332 break; 333 } 334 case Bytecodes::_jsr_w: 335 { 336 dest = _block_map->at(bytes.get_far_dest()); 337 assert(dest != NULL, "branch desination must start a block."); 338 dest->add_normal_predecessor(current_block); 339 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 340 assert(jsrExit != NULL, "jsr return bci must start a block."); 341 jsr_exit_list->append(jsrExit); 342 break; 343 } 344 345 case Bytecodes::_wide: 346 assert(false, "wide opcodes should not be seen here"); 347 break; 348 case Bytecodes::_athrow: 349 case Bytecodes::_ireturn: 350 case Bytecodes::_lreturn: 351 case Bytecodes::_freturn: 352 case Bytecodes::_dreturn: 353 case Bytecodes::_areturn: 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::_iconst_m1: 663 case Bytecodes::_iconst_0: 664 case Bytecodes::_iconst_1: 665 case Bytecodes::_iconst_2: 666 case Bytecodes::_iconst_3: 667 case Bytecodes::_iconst_4: 668 case Bytecodes::_iconst_5: 669 case Bytecodes::_fconst_0: 670 case Bytecodes::_fconst_1: 671 case Bytecodes::_fconst_2: 672 case Bytecodes::_bipush: 673 case Bytecodes::_sipush: 674 case Bytecodes::_lconst_0: 675 case Bytecodes::_lconst_1: 676 case Bytecodes::_dconst_0: 677 case Bytecodes::_dconst_1: 678 case Bytecodes::_ldc2_w: 679 case Bytecodes::_ldc: 680 case Bytecodes::_ldc_w: 681 case Bytecodes::_iaload: 682 case Bytecodes::_faload: 683 case Bytecodes::_baload: 684 case Bytecodes::_caload: 685 case Bytecodes::_saload: 686 case Bytecodes::_laload: 687 case Bytecodes::_daload: 688 case Bytecodes::_aaload: 689 case Bytecodes::_iastore: 690 case Bytecodes::_fastore: 691 case Bytecodes::_bastore: 692 case Bytecodes::_castore: 693 case Bytecodes::_sastore: 694 case Bytecodes::_lastore: 695 case Bytecodes::_dastore: 696 case Bytecodes::_aastore: 697 case Bytecodes::_pop: 698 case Bytecodes::_pop2: 699 case Bytecodes::_dup: 700 case Bytecodes::_dup_x1: 701 case Bytecodes::_dup_x2: 702 case Bytecodes::_dup2: 703 case Bytecodes::_dup2_x1: 704 case Bytecodes::_dup2_x2: 705 case Bytecodes::_swap: 706 case Bytecodes::_iadd: 707 case Bytecodes::_fadd: 708 case Bytecodes::_isub: 709 case Bytecodes::_fsub: 710 case Bytecodes::_imul: 711 case Bytecodes::_fmul: 712 case Bytecodes::_idiv: 713 case Bytecodes::_fdiv: 714 case Bytecodes::_irem: 715 case Bytecodes::_frem: 716 case Bytecodes::_ishl: 717 case Bytecodes::_ishr: 718 case Bytecodes::_iushr: 719 case Bytecodes::_iand: 720 case Bytecodes::_ior: 721 case Bytecodes::_ixor: 722 case Bytecodes::_l2f: 723 case Bytecodes::_l2i: 724 case Bytecodes::_d2f: 725 case Bytecodes::_d2i: 726 case Bytecodes::_fcmpl: 727 case Bytecodes::_fcmpg: 728 case Bytecodes::_ladd: 729 case Bytecodes::_dadd: 730 case Bytecodes::_lsub: 731 case Bytecodes::_dsub: 732 case Bytecodes::_lmul: 733 case Bytecodes::_dmul: 734 case Bytecodes::_ldiv: 735 case Bytecodes::_ddiv: 736 case Bytecodes::_lrem: 737 case Bytecodes::_drem: 738 case Bytecodes::_land: 739 case Bytecodes::_lor: 740 case Bytecodes::_lxor: 741 case Bytecodes::_ineg: 742 case Bytecodes::_fneg: 743 case Bytecodes::_i2f: 744 case Bytecodes::_f2i: 745 case Bytecodes::_i2c: 746 case Bytecodes::_i2s: 747 case Bytecodes::_i2b: 748 case Bytecodes::_lneg: 749 case Bytecodes::_dneg: 750 case Bytecodes::_l2d: 751 case Bytecodes::_d2l: 752 case Bytecodes::_lshl: 753 case Bytecodes::_lshr: 754 case Bytecodes::_lushr: 755 case Bytecodes::_i2l: 756 case Bytecodes::_i2d: 757 case Bytecodes::_f2l: 758 case Bytecodes::_f2d: 759 case Bytecodes::_lcmp: 760 case Bytecodes::_dcmpl: 761 case Bytecodes::_dcmpg: 762 case Bytecodes::_ifeq: 763 case Bytecodes::_ifne: 764 case Bytecodes::_iflt: 765 case Bytecodes::_ifge: 766 case Bytecodes::_ifgt: 767 case Bytecodes::_ifle: 768 case Bytecodes::_tableswitch: 769 case Bytecodes::_ireturn: 770 case Bytecodes::_freturn: 771 case Bytecodes::_if_icmpeq: 772 case Bytecodes::_if_icmpne: 773 case Bytecodes::_if_icmplt: 774 case Bytecodes::_if_icmpge: 775 case Bytecodes::_if_icmpgt: 776 case Bytecodes::_if_icmple: 777 case Bytecodes::_lreturn: 778 case Bytecodes::_dreturn: 779 case Bytecodes::_if_acmpeq: 780 case Bytecodes::_if_acmpne: 781 case Bytecodes::_jsr: 782 case Bytecodes::_jsr_w: 783 case Bytecodes::_getstatic: 784 case Bytecodes::_putstatic: 785 case Bytecodes::_getfield: 786 case Bytecodes::_putfield: 787 case Bytecodes::_invokevirtual: 788 case Bytecodes::_invokespecial: 789 case Bytecodes::_invokestatic: 790 case Bytecodes::_invokeinterface: 791 case Bytecodes::_invokedynamic: 792 case Bytecodes::_newarray: 793 case Bytecodes::_anewarray: 794 case Bytecodes::_checkcast: 795 case Bytecodes::_arraylength: 796 case Bytecodes::_instanceof: 797 case Bytecodes::_athrow: 798 case Bytecodes::_areturn: 799 case Bytecodes::_monitorenter: 800 case Bytecodes::_monitorexit: 801 case Bytecodes::_ifnull: 802 case Bytecodes::_ifnonnull: 803 case Bytecodes::_multianewarray: 804 case Bytecodes::_lookupswitch: 805 // These bytecodes have no effect on the method's locals. 806 break; 807 808 case Bytecodes::_return: 809 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) { 810 // return from Object.init implicitly registers a finalizer 811 // for the receiver if needed, so keep it alive. 812 load_one(0); 813 } 814 break; 815 816 817 case Bytecodes::_lload: 818 case Bytecodes::_dload: 819 load_two(instruction->get_index()); 820 break; 821 822 case Bytecodes::_lload_0: 823 case Bytecodes::_dload_0: 824 load_two(0); 825 break; 826 827 case Bytecodes::_lload_1: 828 case Bytecodes::_dload_1: 829 load_two(1); 830 break; 831 832 case Bytecodes::_lload_2: 833 case Bytecodes::_dload_2: 834 load_two(2); 835 break; 836 837 case Bytecodes::_lload_3: 838 case Bytecodes::_dload_3: 839 load_two(3); 840 break; 841 842 case Bytecodes::_iload: 843 case Bytecodes::_iinc: 844 case Bytecodes::_fload: 845 case Bytecodes::_aload: 846 case Bytecodes::_ret: 847 load_one(instruction->get_index()); 848 break; 849 850 case Bytecodes::_iload_0: 851 case Bytecodes::_fload_0: 852 case Bytecodes::_aload_0: 853 load_one(0); 854 break; 855 856 case Bytecodes::_iload_1: 857 case Bytecodes::_fload_1: 858 case Bytecodes::_aload_1: 859 load_one(1); 860 break; 861 862 case Bytecodes::_iload_2: 863 case Bytecodes::_fload_2: 864 case Bytecodes::_aload_2: 865 load_one(2); 866 break; 867 868 case Bytecodes::_iload_3: 869 case Bytecodes::_fload_3: 870 case Bytecodes::_aload_3: 871 load_one(3); 872 break; 873 874 case Bytecodes::_lstore: 875 case Bytecodes::_dstore: 876 store_two(localNum = instruction->get_index()); 877 break; 878 879 case Bytecodes::_lstore_0: 880 case Bytecodes::_dstore_0: 881 store_two(0); 882 break; 883 884 case Bytecodes::_lstore_1: 885 case Bytecodes::_dstore_1: 886 store_two(1); 887 break; 888 889 case Bytecodes::_lstore_2: 890 case Bytecodes::_dstore_2: 891 store_two(2); 892 break; 893 894 case Bytecodes::_lstore_3: 895 case Bytecodes::_dstore_3: 896 store_two(3); 897 break; 898 899 case Bytecodes::_istore: 900 case Bytecodes::_fstore: 901 case Bytecodes::_astore: 902 store_one(instruction->get_index()); 903 break; 904 905 case Bytecodes::_istore_0: 906 case Bytecodes::_fstore_0: 907 case Bytecodes::_astore_0: 908 store_one(0); 909 break; 910 911 case Bytecodes::_istore_1: 912 case Bytecodes::_fstore_1: 913 case Bytecodes::_astore_1: 914 store_one(1); 915 break; 916 917 case Bytecodes::_istore_2: 918 case Bytecodes::_fstore_2: 919 case Bytecodes::_astore_2: 920 store_one(2); 921 break; 922 923 case Bytecodes::_istore_3: 924 case Bytecodes::_fstore_3: 925 case Bytecodes::_astore_3: 926 store_one(3); 927 break; 928 929 case Bytecodes::_wide: 930 fatal("Iterator should skip this bytecode"); 931 break; 932 933 default: 934 tty->print("unexpected opcode: %d\n", instruction->cur_bc()); 935 ShouldNotReachHere(); 936 break; 937 } 938 } 939 940 void MethodLiveness::BasicBlock::load_two(int local) { 941 load_one(local); 942 load_one(local+1); 943 } 944 945 void MethodLiveness::BasicBlock::load_one(int local) { 946 if (!_kill.at(local)) { 947 _gen.at_put(local, true); 948 } 949 } 950 951 void MethodLiveness::BasicBlock::store_two(int local) { 952 store_one(local); 953 store_one(local+1); 954 } 955 956 void MethodLiveness::BasicBlock::store_one(int local) { 957 if (!_gen.at(local)) { 958 _kill.at_put(local, true); 959 } 960 } 961 962 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) { 963 // These set operations could be combined for efficiency if the 964 // performance of this analysis becomes an issue. 965 _entry.set_union(_normal_exit); 966 _entry.set_difference(_kill); 967 _entry.set_union(_gen); 968 969 // Note that we merge information from our exceptional successors 970 // just once, rather than at individual bytecodes. 971 _entry.set_union(_exception_exit); 972 973 if (TraceLivenessGen) { 974 tty->print_cr(" ** Visiting block at %d **", start_bci()); 975 print_on(tty); 976 } 977 978 int i; 979 for (i=_normal_predecessors->length()-1; i>=0; i--) { 980 BasicBlock *block = _normal_predecessors->at(i); 981 if (block->merge_normal(_entry)) { 982 ml->work_list_add(block); 983 } 984 } 985 for (i=_exception_predecessors->length()-1; i>=0; i--) { 986 BasicBlock *block = _exception_predecessors->at(i); 987 if (block->merge_exception(_entry)) { 988 ml->work_list_add(block); 989 } 990 } 991 } 992 993 bool MethodLiveness::BasicBlock::merge_normal(BitMap other) { 994 return _normal_exit.set_union_with_result(other); 995 } 996 997 bool MethodLiveness::BasicBlock::merge_exception(BitMap other) { 998 return _exception_exit.set_union_with_result(other); 999 } 1000 1001 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) { 1002 MethodLivenessResult answer(NEW_RESOURCE_ARRAY(BitMap::bm_word_t, _analyzer->bit_map_size_words()), 1003 _analyzer->bit_map_size_bits()); 1004 answer.set_is_valid(); 1005 1006 #ifndef ASSERT 1007 if (bci == start_bci()) { 1008 answer.set_from(_entry); 1009 return answer; 1010 } 1011 #endif 1012 1013 #ifdef ASSERT 1014 ResourceMark rm; 1015 BitMap g(_gen.size()); g.set_from(_gen); 1016 BitMap k(_kill.size()); k.set_from(_kill); 1017 #endif 1018 if (_last_bci != bci || trueInDebug) { 1019 ciBytecodeStream bytes(method); 1020 bytes.reset_to_bci(bci); 1021 bytes.set_max_bci(limit_bci()); 1022 compute_gen_kill_range(&bytes); 1023 assert(_last_bci != bci || 1024 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect"); 1025 _last_bci = bci; 1026 } 1027 1028 answer.clear(); 1029 answer.set_union(_normal_exit); 1030 answer.set_difference(_kill); 1031 answer.set_union(_gen); 1032 answer.set_union(_exception_exit); 1033 1034 #ifdef ASSERT 1035 if (bci == start_bci()) { 1036 assert(answer.is_same(_entry), "optimized answer must be accurate"); 1037 } 1038 #endif 1039 1040 return answer; 1041 } 1042 1043 #ifndef PRODUCT 1044 1045 void MethodLiveness::BasicBlock::print_on(outputStream *os) const { 1046 os->print_cr("==================================================================="); 1047 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci); 1048 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length()); 1049 int i; 1050 for (i=0; i < _normal_predecessors->length(); i++) { 1051 os->print(" %4d", _normal_predecessors->at(i)->start_bci()); 1052 } 1053 os->cr(); 1054 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length()); 1055 for (i=0; i < _exception_predecessors->length(); i++) { 1056 os->print(" %4d", _exception_predecessors->at(i)->start_bci()); 1057 } 1058 os->cr(); 1059 os->print (" Normal Exit : "); 1060 _normal_exit.print_on(os); 1061 os->print (" Gen : "); 1062 _gen.print_on(os); 1063 os->print (" Kill : "); 1064 _kill.print_on(os); 1065 os->print (" Exception Exit: "); 1066 _exception_exit.print_on(os); 1067 os->print (" Entry : "); 1068 _entry.print_on(os); 1069 } 1070 1071 #endif // PRODUCT