1 /* 2 * Copyright (c) 1998, 2021, 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 "classfile/vmIntrinsics.hpp" 30 #include "compiler/methodLiveness.hpp" 31 #include "interpreter/bytecode.hpp" 32 #include "interpreter/bytecodes.hpp" 33 #include "memory/allocation.inline.hpp" 34 #include "memory/resourceArea.hpp" 35 #include "utilities/bitMap.inline.hpp" 36 37 // The MethodLiveness class performs a simple liveness analysis on a method 38 // in order to decide which locals are live (that is, will be used again) at 39 // a particular bytecode index (bci). 40 // 41 // The algorithm goes: 42 // 43 // 1. Break the method into a set of basic blocks. For each basic block we 44 // also keep track of its set of predecessors through normal control flow 45 // and predecessors through exceptional control flow. 46 // 47 // 2. For each basic block, compute two sets, gen (the set of values used before 48 // they are defined) and kill (the set of values defined before they are used) 49 // in the basic block. A basic block "needs" the locals in its gen set to 50 // perform its computation. A basic block "provides" values for the locals in 51 // its kill set, allowing a need from a successor to be ignored. 52 // 53 // 3. Liveness information (the set of locals which are needed) is pushed backwards through 54 // the program, from blocks to their predecessors. We compute and store liveness 55 // information for the normal/exceptional exit paths for each basic block. When 56 // this process reaches a fixed point, we are done. 57 // 58 // 4. When we are asked about the liveness at a particular bci with a basic block, we 59 // compute gen/kill sets which represent execution from that bci to the exit of 60 // its blocks. We then compose this range gen/kill information with the normal 61 // and exceptional exit information for the block to produce liveness information 62 // at that bci. 63 // 64 // The algorithm is approximate in many respects. Notably: 65 // 66 // 1. We do not do the analysis necessary to match jsr's with the appropriate ret. 67 // Instead we make the conservative assumption that any ret can return to any 68 // jsr return site. 69 // 2. Instead of computing the effects of exceptions at every instruction, we 70 // summarize the effects of all exceptional continuations from the block as 71 // a single set (_exception_exit), losing some information but simplifying the 72 // analysis. 73 74 MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method) 75 #ifdef COMPILER1 76 : _bci_block_start(arena, method->code_size()) 77 #endif 78 { 79 _arena = arena; 80 _method = method; 81 _bit_map_size_bits = method->max_locals(); 82 } 83 84 void MethodLiveness::compute_liveness() { 85 #ifndef PRODUCT 86 if (TraceLivenessGen) { 87 tty->print_cr("################################################################"); 88 tty->print("# Computing liveness information for "); 89 method()->print_short_name(); 90 } 91 #endif 92 93 init_basic_blocks(); 94 init_gen_kill(); 95 propagate_liveness(); 96 } 97 98 99 void MethodLiveness::init_basic_blocks() { 100 int method_len = method()->code_size(); 101 ciMethodBlocks *mblocks = method()->get_method_blocks(); 102 103 // Create an array to store the bci->BasicBlock mapping. 104 _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL); 105 106 _block_count = mblocks->num_blocks(); 107 _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count); 108 109 // Used for patching up jsr/ret control flow. 110 GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5); 111 GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5); 112 113 // generate our block list from ciMethodBlocks 114 for (int blk = 0; blk < _block_count; blk++) { 115 ciBlock *cib = mblocks->block(blk); 116 int start_bci = cib->start_bci(); 117 _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci()); 118 _block_map->at_put(start_bci, _block_list[blk]); 119 #ifdef COMPILER1 120 // mark all bcis where a new basic block starts 121 _bci_block_start.set_bit(start_bci); 122 #endif // COMPILER1 123 } 124 // fill in the predecessors of blocks 125 ciBytecodeStream bytes(method()); 126 127 for (int blk = 0; blk < _block_count; blk++) { 128 BasicBlock *current_block = _block_list[blk]; 129 int bci = mblocks->block(blk)->control_bci(); 130 131 if (bci == ciBlock::fall_through_bci) { 132 int limit = current_block->limit_bci(); 133 if (limit < method_len) { 134 BasicBlock *next = _block_map->at(limit); 135 assert( next != NULL, "must be a block immediately following this one."); 136 next->add_normal_predecessor(current_block); 137 } 138 continue; 139 } 140 bytes.reset_to_bci(bci); 141 Bytecodes::Code code = bytes.next(); 142 BasicBlock *dest; 143 144 // Now we need to interpret the instruction's effect 145 // on control flow. 146 assert (current_block != NULL, "we must have a current block"); 147 switch (code) { 148 case Bytecodes::_ifeq: 149 case Bytecodes::_ifne: 150 case Bytecodes::_iflt: 151 case Bytecodes::_ifge: 152 case Bytecodes::_ifgt: 153 case Bytecodes::_ifle: 154 case Bytecodes::_if_icmpeq: 155 case Bytecodes::_if_icmpne: 156 case Bytecodes::_if_icmplt: 157 case Bytecodes::_if_icmpge: 158 case Bytecodes::_if_icmpgt: 159 case Bytecodes::_if_icmple: 160 case Bytecodes::_if_acmpeq: 161 case Bytecodes::_if_acmpne: 162 case Bytecodes::_ifnull: 163 case Bytecodes::_ifnonnull: 164 // Two way branch. Set predecessors at each destination. 165 dest = _block_map->at(bytes.next_bci()); 166 assert(dest != NULL, "must be a block immediately following this one."); 167 dest->add_normal_predecessor(current_block); 168 169 dest = _block_map->at(bytes.get_dest()); 170 assert(dest != NULL, "branch desination must start a block."); 171 dest->add_normal_predecessor(current_block); 172 break; 173 case Bytecodes::_goto: 174 dest = _block_map->at(bytes.get_dest()); 175 assert(dest != NULL, "branch desination must start a block."); 176 dest->add_normal_predecessor(current_block); 177 break; 178 case Bytecodes::_goto_w: 179 dest = _block_map->at(bytes.get_far_dest()); 180 assert(dest != NULL, "branch desination must start a block."); 181 dest->add_normal_predecessor(current_block); 182 break; 183 case Bytecodes::_tableswitch: 184 { 185 Bytecode_tableswitch tableswitch(&bytes); 186 187 int len = tableswitch.length(); 188 189 dest = _block_map->at(bci + tableswitch.default_offset()); 190 assert(dest != NULL, "branch desination must start a block."); 191 dest->add_normal_predecessor(current_block); 192 while (--len >= 0) { 193 dest = _block_map->at(bci + tableswitch.dest_offset_at(len)); 194 assert(dest != NULL, "branch desination must start a block."); 195 dest->add_normal_predecessor(current_block); 196 } 197 break; 198 } 199 200 case Bytecodes::_lookupswitch: 201 { 202 Bytecode_lookupswitch lookupswitch(&bytes); 203 204 int npairs = lookupswitch.number_of_pairs(); 205 206 dest = _block_map->at(bci + lookupswitch.default_offset()); 207 assert(dest != NULL, "branch desination must start a block."); 208 dest->add_normal_predecessor(current_block); 209 while(--npairs >= 0) { 210 LookupswitchPair pair = lookupswitch.pair_at(npairs); 211 dest = _block_map->at( bci + pair.offset()); 212 assert(dest != NULL, "branch desination must start a block."); 213 dest->add_normal_predecessor(current_block); 214 } 215 break; 216 } 217 218 case Bytecodes::_jsr: 219 { 220 assert(bytes.is_wide()==false, "sanity check"); 221 dest = _block_map->at(bytes.get_dest()); 222 assert(dest != NULL, "branch desination must start a block."); 223 dest->add_normal_predecessor(current_block); 224 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 225 assert(jsrExit != NULL, "jsr return bci must start a block."); 226 jsr_exit_list->append(jsrExit); 227 break; 228 } 229 case Bytecodes::_jsr_w: 230 { 231 dest = _block_map->at(bytes.get_far_dest()); 232 assert(dest != NULL, "branch desination must start a block."); 233 dest->add_normal_predecessor(current_block); 234 BasicBlock *jsrExit = _block_map->at(current_block->limit_bci()); 235 assert(jsrExit != NULL, "jsr return bci must start a block."); 236 jsr_exit_list->append(jsrExit); 237 break; 238 } 239 240 case Bytecodes::_wide: 241 assert(false, "wide opcodes should not be seen here"); 242 break; 243 case Bytecodes::_athrow: 244 case Bytecodes::_ireturn: 245 case Bytecodes::_lreturn: 246 case Bytecodes::_freturn: 247 case Bytecodes::_dreturn: 248 case Bytecodes::_areturn: 249 case Bytecodes::_return: 250 // These opcodes are not the normal predecessors of any other opcodes. 251 break; 252 case Bytecodes::_ret: 253 // We will patch up jsr/rets in a subsequent pass. 254 ret_list->append(current_block); 255 break; 256 default: 257 // Do nothing. 258 break; 259 } 260 } 261 // Patch up the jsr/ret's. We conservatively assume that any ret 262 // can return to any jsr site. 263 int ret_list_len = ret_list->length(); 264 int jsr_exit_list_len = jsr_exit_list->length(); 265 if (ret_list_len > 0 && jsr_exit_list_len > 0) { 266 for (int i = jsr_exit_list_len - 1; i >= 0; i--) { 267 BasicBlock *jsrExit = jsr_exit_list->at(i); 268 for (int i = ret_list_len - 1; i >= 0; i--) { 269 jsrExit->add_normal_predecessor(ret_list->at(i)); 270 } 271 } 272 } 273 274 // Compute exception edges. 275 for (int b=_block_count-1; b >= 0; b--) { 276 BasicBlock *block = _block_list[b]; 277 int block_start = block->start_bci(); 278 int block_limit = block->limit_bci(); 279 ciExceptionHandlerStream handlers(method()); 280 for (; !handlers.is_done(); handlers.next()) { 281 ciExceptionHandler* handler = handlers.handler(); 282 int start = handler->start(); 283 int limit = handler->limit(); 284 int handler_bci = handler->handler_bci(); 285 286 int intersect_start = MAX2(block_start, start); 287 int intersect_limit = MIN2(block_limit, limit); 288 if (intersect_start < intersect_limit) { 289 // The catch range has a nonempty intersection with this 290 // basic block. That means this basic block can be an 291 // exceptional predecessor. 292 _block_map->at(handler_bci)->add_exception_predecessor(block); 293 294 if (handler->is_catch_all()) { 295 // This is a catch-all block. 296 if (intersect_start == block_start && intersect_limit == block_limit) { 297 // The basic block is entirely contained in this catch-all block. 298 // Skip the rest of the exception handlers -- they can never be 299 // reached in execution. 300 break; 301 } 302 } 303 } 304 } 305 } 306 } 307 308 void MethodLiveness::init_gen_kill() { 309 for (int i=_block_count-1; i >= 0; i--) { 310 _block_list[i]->compute_gen_kill(method()); 311 } 312 } 313 314 void MethodLiveness::propagate_liveness() { 315 int num_blocks = _block_count; 316 BasicBlock *block; 317 318 // We start our work list off with all blocks in it. 319 // Alternately, we could start off the work list with the list of all 320 // blocks which could exit the method directly, along with one block 321 // from any infinite loop. If this matters, it can be changed. It 322 // may not be clear from looking at the code, but the order of the 323 // workList will be the opposite of the creation order of the basic 324 // blocks, which should be decent for quick convergence (with the 325 // possible exception of exception handlers, which are all created 326 // early). 327 _work_list = NULL; 328 for (int i = 0; i < num_blocks; i++) { 329 block = _block_list[i]; 330 block->set_next(_work_list); 331 block->set_on_work_list(true); 332 _work_list = block; 333 } 334 335 336 while ((block = work_list_get()) != NULL) { 337 block->propagate(this); 338 } 339 } 340 341 void MethodLiveness::work_list_add(BasicBlock *block) { 342 if (!block->on_work_list()) { 343 block->set_next(_work_list); 344 block->set_on_work_list(true); 345 _work_list = block; 346 } 347 } 348 349 MethodLiveness::BasicBlock *MethodLiveness::work_list_get() { 350 BasicBlock *block = _work_list; 351 if (block != NULL) { 352 block->set_on_work_list(false); 353 _work_list = block->next(); 354 } 355 return block; 356 } 357 358 359 MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) { 360 int bci = entry_bci; 361 bool is_entry = false; 362 if (entry_bci == InvocationEntryBci) { 363 is_entry = true; 364 bci = 0; 365 } 366 367 MethodLivenessResult answer; 368 369 if (_block_count > 0) { 370 371 assert( 0 <= bci && bci < method()->code_size(), "bci out of range" ); 372 BasicBlock *block = _block_map->at(bci); 373 // We may not be at the block start, so search backwards to find the block 374 // containing bci. 375 int t = bci; 376 while (block == NULL && t > 0) { 377 block = _block_map->at(--t); 378 } 379 guarantee(block != NULL, "invalid bytecode index; must be instruction index"); 380 assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci."); 381 382 answer = block->get_liveness_at(method(), bci); 383 384 if (is_entry && method()->is_synchronized() && !method()->is_static()) { 385 // Synchronized methods use the receiver once on entry. 386 answer.at_put(0, true); 387 } 388 389 #ifndef PRODUCT 390 if (TraceLivenessQuery) { 391 tty->print("Liveness query of "); 392 method()->print_short_name(); 393 tty->print(" @ %d : result is ", bci); 394 answer.print_on(tty); 395 } 396 #endif 397 } 398 399 return answer; 400 } 401 402 MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) : 403 _entry(analyzer->arena(), analyzer->bit_map_size_bits()), 404 _normal_exit(analyzer->arena(), analyzer->bit_map_size_bits()), 405 _exception_exit(analyzer->arena(), analyzer->bit_map_size_bits()), 406 _gen(analyzer->arena(), analyzer->bit_map_size_bits()), 407 _kill(analyzer->arena(), analyzer->bit_map_size_bits()), 408 _last_bci(-1) { 409 _analyzer = analyzer; 410 _start_bci = start; 411 _limit_bci = limit; 412 _normal_predecessors = 413 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 414 _exception_predecessors = 415 new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL); 416 } 417 418 419 420 MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) { 421 int start = _start_bci; 422 int limit = _limit_bci; 423 424 if (TraceLivenessGen) { 425 tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci); 426 } 427 428 GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors; 429 430 assert (start < split_bci && split_bci < limit, "improper split"); 431 432 // Make a new block to cover the first half of the range. 433 BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci); 434 435 // Assign correct values to the second half (this) 436 _normal_predecessors = first_half->_normal_predecessors; 437 _start_bci = split_bci; 438 add_normal_predecessor(first_half); 439 440 // Assign correct predecessors to the new first half 441 first_half->_normal_predecessors = save_predecessors; 442 443 return first_half; 444 } 445 446 void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) { 447 ciBytecodeStream bytes(method); 448 bytes.reset_to_bci(start_bci()); 449 bytes.set_max_bci(limit_bci()); 450 compute_gen_kill_range(&bytes); 451 452 } 453 454 void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) { 455 _gen.clear(); 456 _kill.clear(); 457 458 while (bytes->next() != ciBytecodeStream::EOBC()) { 459 compute_gen_kill_single(bytes); 460 } 461 } 462 463 void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) { 464 // We prohibit _gen and _kill from having locals in common. If we 465 // know that one is definitely going to be applied before the other, 466 // we could save some computation time by relaxing this prohibition. 467 468 switch (instruction->cur_bc()) { 469 case Bytecodes::_nop: 470 case Bytecodes::_goto: 471 case Bytecodes::_goto_w: 472 case Bytecodes::_aconst_null: 473 case Bytecodes::_new: 474 case Bytecodes::_aconst_init: 475 case Bytecodes::_withfield: 476 case Bytecodes::_iconst_m1: 477 case Bytecodes::_iconst_0: 478 case Bytecodes::_iconst_1: 479 case Bytecodes::_iconst_2: 480 case Bytecodes::_iconst_3: 481 case Bytecodes::_iconst_4: 482 case Bytecodes::_iconst_5: 483 case Bytecodes::_fconst_0: 484 case Bytecodes::_fconst_1: 485 case Bytecodes::_fconst_2: 486 case Bytecodes::_bipush: 487 case Bytecodes::_sipush: 488 case Bytecodes::_lconst_0: 489 case Bytecodes::_lconst_1: 490 case Bytecodes::_dconst_0: 491 case Bytecodes::_dconst_1: 492 case Bytecodes::_ldc2_w: 493 case Bytecodes::_ldc: 494 case Bytecodes::_ldc_w: 495 case Bytecodes::_iaload: 496 case Bytecodes::_faload: 497 case Bytecodes::_baload: 498 case Bytecodes::_caload: 499 case Bytecodes::_saload: 500 case Bytecodes::_laload: 501 case Bytecodes::_daload: 502 case Bytecodes::_aaload: 503 case Bytecodes::_iastore: 504 case Bytecodes::_fastore: 505 case Bytecodes::_bastore: 506 case Bytecodes::_castore: 507 case Bytecodes::_sastore: 508 case Bytecodes::_lastore: 509 case Bytecodes::_dastore: 510 case Bytecodes::_aastore: 511 case Bytecodes::_pop: 512 case Bytecodes::_pop2: 513 case Bytecodes::_dup: 514 case Bytecodes::_dup_x1: 515 case Bytecodes::_dup_x2: 516 case Bytecodes::_dup2: 517 case Bytecodes::_dup2_x1: 518 case Bytecodes::_dup2_x2: 519 case Bytecodes::_swap: 520 case Bytecodes::_iadd: 521 case Bytecodes::_fadd: 522 case Bytecodes::_isub: 523 case Bytecodes::_fsub: 524 case Bytecodes::_imul: 525 case Bytecodes::_fmul: 526 case Bytecodes::_idiv: 527 case Bytecodes::_fdiv: 528 case Bytecodes::_irem: 529 case Bytecodes::_frem: 530 case Bytecodes::_ishl: 531 case Bytecodes::_ishr: 532 case Bytecodes::_iushr: 533 case Bytecodes::_iand: 534 case Bytecodes::_ior: 535 case Bytecodes::_ixor: 536 case Bytecodes::_l2f: 537 case Bytecodes::_l2i: 538 case Bytecodes::_d2f: 539 case Bytecodes::_d2i: 540 case Bytecodes::_fcmpl: 541 case Bytecodes::_fcmpg: 542 case Bytecodes::_ladd: 543 case Bytecodes::_dadd: 544 case Bytecodes::_lsub: 545 case Bytecodes::_dsub: 546 case Bytecodes::_lmul: 547 case Bytecodes::_dmul: 548 case Bytecodes::_ldiv: 549 case Bytecodes::_ddiv: 550 case Bytecodes::_lrem: 551 case Bytecodes::_drem: 552 case Bytecodes::_land: 553 case Bytecodes::_lor: 554 case Bytecodes::_lxor: 555 case Bytecodes::_ineg: 556 case Bytecodes::_fneg: 557 case Bytecodes::_i2f: 558 case Bytecodes::_f2i: 559 case Bytecodes::_i2c: 560 case Bytecodes::_i2s: 561 case Bytecodes::_i2b: 562 case Bytecodes::_lneg: 563 case Bytecodes::_dneg: 564 case Bytecodes::_l2d: 565 case Bytecodes::_d2l: 566 case Bytecodes::_lshl: 567 case Bytecodes::_lshr: 568 case Bytecodes::_lushr: 569 case Bytecodes::_i2l: 570 case Bytecodes::_i2d: 571 case Bytecodes::_f2l: 572 case Bytecodes::_f2d: 573 case Bytecodes::_lcmp: 574 case Bytecodes::_dcmpl: 575 case Bytecodes::_dcmpg: 576 case Bytecodes::_ifeq: 577 case Bytecodes::_ifne: 578 case Bytecodes::_iflt: 579 case Bytecodes::_ifge: 580 case Bytecodes::_ifgt: 581 case Bytecodes::_ifle: 582 case Bytecodes::_tableswitch: 583 case Bytecodes::_ireturn: 584 case Bytecodes::_freturn: 585 case Bytecodes::_if_icmpeq: 586 case Bytecodes::_if_icmpne: 587 case Bytecodes::_if_icmplt: 588 case Bytecodes::_if_icmpge: 589 case Bytecodes::_if_icmpgt: 590 case Bytecodes::_if_icmple: 591 case Bytecodes::_lreturn: 592 case Bytecodes::_dreturn: 593 case Bytecodes::_if_acmpeq: 594 case Bytecodes::_if_acmpne: 595 case Bytecodes::_jsr: 596 case Bytecodes::_jsr_w: 597 case Bytecodes::_getstatic: 598 case Bytecodes::_putstatic: 599 case Bytecodes::_getfield: 600 case Bytecodes::_putfield: 601 case Bytecodes::_invokevirtual: 602 case Bytecodes::_invokespecial: 603 case Bytecodes::_invokestatic: 604 case Bytecodes::_invokeinterface: 605 case Bytecodes::_invokedynamic: 606 case Bytecodes::_newarray: 607 case Bytecodes::_anewarray: 608 case Bytecodes::_checkcast: 609 case Bytecodes::_arraylength: 610 case Bytecodes::_instanceof: 611 case Bytecodes::_athrow: 612 case Bytecodes::_areturn: 613 case Bytecodes::_monitorenter: 614 case Bytecodes::_monitorexit: 615 case Bytecodes::_ifnull: 616 case Bytecodes::_ifnonnull: 617 case Bytecodes::_multianewarray: 618 case Bytecodes::_lookupswitch: 619 // These bytecodes have no effect on the method's locals. 620 break; 621 622 case Bytecodes::_return: 623 if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) { 624 // return from Object.init implicitly registers a finalizer 625 // for the receiver if needed, so keep it alive. 626 load_one(0); 627 } 628 break; 629 630 631 case Bytecodes::_lload: 632 case Bytecodes::_dload: 633 load_two(instruction->get_index()); 634 break; 635 636 case Bytecodes::_lload_0: 637 case Bytecodes::_dload_0: 638 load_two(0); 639 break; 640 641 case Bytecodes::_lload_1: 642 case Bytecodes::_dload_1: 643 load_two(1); 644 break; 645 646 case Bytecodes::_lload_2: 647 case Bytecodes::_dload_2: 648 load_two(2); 649 break; 650 651 case Bytecodes::_lload_3: 652 case Bytecodes::_dload_3: 653 load_two(3); 654 break; 655 656 case Bytecodes::_iload: 657 case Bytecodes::_iinc: 658 case Bytecodes::_fload: 659 case Bytecodes::_aload: 660 case Bytecodes::_ret: 661 load_one(instruction->get_index()); 662 break; 663 664 case Bytecodes::_iload_0: 665 case Bytecodes::_fload_0: 666 case Bytecodes::_aload_0: 667 load_one(0); 668 break; 669 670 case Bytecodes::_iload_1: 671 case Bytecodes::_fload_1: 672 case Bytecodes::_aload_1: 673 load_one(1); 674 break; 675 676 case Bytecodes::_iload_2: 677 case Bytecodes::_fload_2: 678 case Bytecodes::_aload_2: 679 load_one(2); 680 break; 681 682 case Bytecodes::_iload_3: 683 case Bytecodes::_fload_3: 684 case Bytecodes::_aload_3: 685 load_one(3); 686 break; 687 688 case Bytecodes::_lstore: 689 case Bytecodes::_dstore: 690 store_two(instruction->get_index()); 691 break; 692 693 case Bytecodes::_lstore_0: 694 case Bytecodes::_dstore_0: 695 store_two(0); 696 break; 697 698 case Bytecodes::_lstore_1: 699 case Bytecodes::_dstore_1: 700 store_two(1); 701 break; 702 703 case Bytecodes::_lstore_2: 704 case Bytecodes::_dstore_2: 705 store_two(2); 706 break; 707 708 case Bytecodes::_lstore_3: 709 case Bytecodes::_dstore_3: 710 store_two(3); 711 break; 712 713 case Bytecodes::_istore: 714 case Bytecodes::_fstore: 715 case Bytecodes::_astore: 716 store_one(instruction->get_index()); 717 break; 718 719 case Bytecodes::_istore_0: 720 case Bytecodes::_fstore_0: 721 case Bytecodes::_astore_0: 722 store_one(0); 723 break; 724 725 case Bytecodes::_istore_1: 726 case Bytecodes::_fstore_1: 727 case Bytecodes::_astore_1: 728 store_one(1); 729 break; 730 731 case Bytecodes::_istore_2: 732 case Bytecodes::_fstore_2: 733 case Bytecodes::_astore_2: 734 store_one(2); 735 break; 736 737 case Bytecodes::_istore_3: 738 case Bytecodes::_fstore_3: 739 case Bytecodes::_astore_3: 740 store_one(3); 741 break; 742 743 case Bytecodes::_wide: 744 fatal("Iterator should skip this bytecode"); 745 break; 746 747 default: 748 tty->print("unexpected opcode: %d\n", instruction->cur_bc()); 749 ShouldNotReachHere(); 750 break; 751 } 752 } 753 754 void MethodLiveness::BasicBlock::load_two(int local) { 755 load_one(local); 756 load_one(local+1); 757 } 758 759 void MethodLiveness::BasicBlock::load_one(int local) { 760 if (!_kill.at(local)) { 761 _gen.at_put(local, true); 762 } 763 } 764 765 void MethodLiveness::BasicBlock::store_two(int local) { 766 store_one(local); 767 store_one(local+1); 768 } 769 770 void MethodLiveness::BasicBlock::store_one(int local) { 771 if (!_gen.at(local)) { 772 _kill.at_put(local, true); 773 } 774 } 775 776 void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) { 777 // These set operations could be combined for efficiency if the 778 // performance of this analysis becomes an issue. 779 _entry.set_union(_normal_exit); 780 _entry.set_difference(_kill); 781 _entry.set_union(_gen); 782 783 // Note that we merge information from our exceptional successors 784 // just once, rather than at individual bytecodes. 785 _entry.set_union(_exception_exit); 786 787 if (TraceLivenessGen) { 788 tty->print_cr(" ** Visiting block at %d **", start_bci()); 789 print_on(tty); 790 } 791 792 int i; 793 for (i=_normal_predecessors->length()-1; i>=0; i--) { 794 BasicBlock *block = _normal_predecessors->at(i); 795 if (block->merge_normal(_entry)) { 796 ml->work_list_add(block); 797 } 798 } 799 for (i=_exception_predecessors->length()-1; i>=0; i--) { 800 BasicBlock *block = _exception_predecessors->at(i); 801 if (block->merge_exception(_entry)) { 802 ml->work_list_add(block); 803 } 804 } 805 } 806 807 bool MethodLiveness::BasicBlock::merge_normal(const BitMap& other) { 808 return _normal_exit.set_union_with_result(other); 809 } 810 811 bool MethodLiveness::BasicBlock::merge_exception(const BitMap& other) { 812 return _exception_exit.set_union_with_result(other); 813 } 814 815 MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) { 816 MethodLivenessResult answer(_analyzer->bit_map_size_bits()); 817 answer.set_is_valid(); 818 819 #ifndef ASSERT 820 if (bci == start_bci()) { 821 answer.set_from(_entry); 822 return answer; 823 } 824 #endif 825 826 #ifdef ASSERT 827 ResourceMark rm; 828 ResourceBitMap g(_gen.size(), false); g.set_from(_gen); 829 ResourceBitMap k(_kill.size(), false); k.set_from(_kill); 830 #endif 831 if (_last_bci != bci || trueInDebug) { 832 ciBytecodeStream bytes(method); 833 bytes.reset_to_bci(bci); 834 bytes.set_max_bci(limit_bci()); 835 compute_gen_kill_range(&bytes); 836 assert(_last_bci != bci || 837 (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect"); 838 _last_bci = bci; 839 } 840 841 answer.set_union(_normal_exit); 842 answer.set_difference(_kill); 843 answer.set_union(_gen); 844 answer.set_union(_exception_exit); 845 846 #ifdef ASSERT 847 if (bci == start_bci()) { 848 assert(answer.is_same(_entry), "optimized answer must be accurate"); 849 } 850 #endif 851 852 return answer; 853 } 854 855 #ifndef PRODUCT 856 857 void MethodLiveness::BasicBlock::print_on(outputStream *os) const { 858 os->print_cr("==================================================================="); 859 os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci); 860 os->print (" Normal predecessors (%2d) @", _normal_predecessors->length()); 861 int i; 862 for (i=0; i < _normal_predecessors->length(); i++) { 863 os->print(" %4d", _normal_predecessors->at(i)->start_bci()); 864 } 865 os->cr(); 866 os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length()); 867 for (i=0; i < _exception_predecessors->length(); i++) { 868 os->print(" %4d", _exception_predecessors->at(i)->start_bci()); 869 } 870 os->cr(); 871 os->print (" Normal Exit : "); 872 _normal_exit.print_on(os); 873 os->print (" Gen : "); 874 _gen.print_on(os); 875 os->print (" Kill : "); 876 _kill.print_on(os); 877 os->print (" Exception Exit: "); 878 _exception_exit.print_on(os); 879 os->print (" Entry : "); 880 _entry.print_on(os); 881 } 882 883 #endif // PRODUCT --- EOF ---