1 /* 2 * Copyright (c) 1999, 2017, 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 "c1/c1_Canonicalizer.hpp" 27 #include "c1/c1_Optimizer.hpp" 28 #include "c1/c1_ValueMap.hpp" 29 #include "c1/c1_ValueSet.inline.hpp" 30 #include "c1/c1_ValueStack.hpp" 31 #include "memory/resourceArea.hpp" 32 #include "utilities/bitMap.inline.hpp" 33 #include "compiler/compileLog.hpp" 34 35 typedef GrowableArray<ValueSet*> ValueSetList; 36 37 Optimizer::Optimizer(IR* ir) { 38 assert(ir->is_valid(), "IR must be valid"); 39 _ir = ir; 40 } 41 42 class CE_Eliminator: public BlockClosure { 43 private: 44 IR* _hir; 45 int _cee_count; // the number of CEs successfully eliminated 46 int _ifop_count; // the number of IfOps successfully simplified 47 int _has_substitution; 48 49 public: 50 CE_Eliminator(IR* hir) : _hir(hir), _cee_count(0), _ifop_count(0) { 51 _has_substitution = false; 52 _hir->iterate_preorder(this); 53 if (_has_substitution) { 54 // substituted some ifops/phis, so resolve the substitution 55 SubstitutionResolver sr(_hir); 56 } 57 58 CompileLog* log = _hir->compilation()->log(); 59 if (log != NULL) 60 log->set_context("optimize name='cee'"); 61 } 62 63 ~CE_Eliminator() { 64 CompileLog* log = _hir->compilation()->log(); 65 if (log != NULL) 66 log->clear_context(); // skip marker if nothing was printed 67 } 68 69 int cee_count() const { return _cee_count; } 70 int ifop_count() const { return _ifop_count; } 71 72 void adjust_exception_edges(BlockBegin* block, BlockBegin* sux) { 73 int e = sux->number_of_exception_handlers(); 74 for (int i = 0; i < e; i++) { 75 BlockBegin* xhandler = sux->exception_handler_at(i); 76 block->add_exception_handler(xhandler); 77 78 assert(xhandler->is_predecessor(sux), "missing predecessor"); 79 if (sux->number_of_preds() == 0) { 80 // sux is disconnected from graph so disconnect from exception handlers 81 xhandler->remove_predecessor(sux); 82 } 83 if (!xhandler->is_predecessor(block)) { 84 xhandler->add_predecessor(block); 85 } 86 } 87 } 88 89 virtual void block_do(BlockBegin* block); 90 91 private: 92 Value make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval); 93 }; 94 95 void CE_Eliminator::block_do(BlockBegin* block) { 96 // 1) find conditional expression 97 // check if block ends with an If 98 If* if_ = block->end()->as_If(); 99 if (if_ == NULL) return; 100 101 // check if If works on int or object types 102 // (we cannot handle If's working on long, float or doubles yet, 103 // since IfOp doesn't support them - these If's show up if cmp 104 // operations followed by If's are eliminated) 105 ValueType* if_type = if_->x()->type(); 106 if (!if_type->is_int() && !if_type->is_object()) return; 107 108 BlockBegin* t_block = if_->tsux(); 109 BlockBegin* f_block = if_->fsux(); 110 Instruction* t_cur = t_block->next(); 111 Instruction* f_cur = f_block->next(); 112 113 // one Constant may be present between BlockBegin and BlockEnd 114 Value t_const = NULL; 115 Value f_const = NULL; 116 if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) { 117 t_const = t_cur; 118 t_cur = t_cur->next(); 119 } 120 if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) { 121 f_const = f_cur; 122 f_cur = f_cur->next(); 123 } 124 125 // check if both branches end with a goto 126 Goto* t_goto = t_cur->as_Goto(); 127 if (t_goto == NULL) return; 128 Goto* f_goto = f_cur->as_Goto(); 129 if (f_goto == NULL) return; 130 131 // check if both gotos merge into the same block 132 BlockBegin* sux = t_goto->default_sux(); 133 if (sux != f_goto->default_sux()) return; 134 135 // check if at least one word was pushed on sux_state 136 // inlining depths must match 137 ValueStack* if_state = if_->state(); 138 ValueStack* sux_state = sux->state(); 139 if (if_state->scope()->level() > sux_state->scope()->level()) { 140 while (sux_state->scope() != if_state->scope()) { 141 if_state = if_state->caller_state(); 142 assert(if_state != NULL, "states do not match up"); 143 } 144 } else if (if_state->scope()->level() < sux_state->scope()->level()) { 145 while (sux_state->scope() != if_state->scope()) { 146 sux_state = sux_state->caller_state(); 147 assert(sux_state != NULL, "states do not match up"); 148 } 149 } 150 151 if (sux_state->stack_size() <= if_state->stack_size()) return; 152 153 // check if phi function is present at end of successor stack and that 154 // only this phi was pushed on the stack 155 Value sux_phi = sux_state->stack_at(if_state->stack_size()); 156 if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return; 157 if (sux_phi->type()->size() != sux_state->stack_size() - if_state->stack_size()) return; 158 159 // get the values that were pushed in the true- and false-branch 160 Value t_value = t_goto->state()->stack_at(if_state->stack_size()); 161 Value f_value = f_goto->state()->stack_at(if_state->stack_size()); 162 163 // backend does not support floats 164 assert(t_value->type()->base() == f_value->type()->base(), "incompatible types"); 165 if (t_value->type()->is_float_kind()) return; 166 167 // check that successor has no other phi functions but sux_phi 168 // this can happen when t_block or f_block contained additonal stores to local variables 169 // that are no longer represented by explicit instructions 170 for_each_phi_fun(sux, phi, 171 if (phi != sux_phi) return; 172 ); 173 // true and false blocks can't have phis 174 for_each_phi_fun(t_block, phi, return; ); 175 for_each_phi_fun(f_block, phi, return; ); 176 177 // Only replace safepoint gotos if state_before information is available (if is a safepoint) 178 bool is_safepoint = if_->is_safepoint(); 179 if (!is_safepoint && (t_goto->is_safepoint() || f_goto->is_safepoint())) { 180 return; 181 } 182 183 // 2) substitute conditional expression 184 // with an IfOp followed by a Goto 185 // cut if_ away and get node before 186 Instruction* cur_end = if_->prev(); 187 188 // append constants of true- and false-block if necessary 189 // clone constants because original block must not be destroyed 190 assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch"); 191 if (t_value == t_const) { 192 t_value = new Constant(t_const->type()); 193 NOT_PRODUCT(t_value->set_printable_bci(if_->printable_bci())); 194 cur_end = cur_end->set_next(t_value); 195 } 196 if (f_value == f_const) { 197 f_value = new Constant(f_const->type()); 198 NOT_PRODUCT(f_value->set_printable_bci(if_->printable_bci())); 199 cur_end = cur_end->set_next(f_value); 200 } 201 202 Value result = make_ifop(if_->x(), if_->cond(), if_->y(), t_value, f_value); 203 assert(result != NULL, "make_ifop must return a non-null instruction"); 204 if (!result->is_linked() && result->can_be_linked()) { 205 NOT_PRODUCT(result->set_printable_bci(if_->printable_bci())); 206 cur_end = cur_end->set_next(result); 207 } 208 209 // append Goto to successor 210 ValueStack* state_before = if_->state_before(); 211 Goto* goto_ = new Goto(sux, state_before, is_safepoint); 212 213 // prepare state for Goto 214 ValueStack* goto_state = if_state; 215 goto_state = goto_state->copy(ValueStack::StateAfter, goto_state->bci()); 216 goto_state->push(result->type(), result); 217 assert(goto_state->is_same(sux_state), "states must match now"); 218 goto_->set_state(goto_state); 219 220 cur_end = cur_end->set_next(goto_, goto_state->bci()); 221 222 // Adjust control flow graph 223 BlockBegin::disconnect_edge(block, t_block); 224 BlockBegin::disconnect_edge(block, f_block); 225 if (t_block->number_of_preds() == 0) { 226 BlockBegin::disconnect_edge(t_block, sux); 227 } 228 adjust_exception_edges(block, t_block); 229 if (f_block->number_of_preds() == 0) { 230 BlockBegin::disconnect_edge(f_block, sux); 231 } 232 adjust_exception_edges(block, f_block); 233 234 // update block end 235 block->set_end(goto_); 236 237 // substitute the phi if possible 238 if (sux_phi->as_Phi()->operand_count() == 1) { 239 assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi"); 240 sux_phi->set_subst(result); 241 _has_substitution = true; 242 } 243 244 // 3) successfully eliminated a conditional expression 245 _cee_count++; 246 if (PrintCEE) { 247 tty->print_cr("%d. CEE in B%d (B%d B%d)", cee_count(), block->block_id(), t_block->block_id(), f_block->block_id()); 248 tty->print_cr("%d. IfOp in B%d", ifop_count(), block->block_id()); 249 } 250 251 _hir->verify(); 252 } 253 254 Value CE_Eliminator::make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval) { 255 if (!OptimizeIfOps) { 256 return new IfOp(x, cond, y, tval, fval); 257 } 258 259 tval = tval->subst(); 260 fval = fval->subst(); 261 if (tval == fval) { 262 _ifop_count++; 263 return tval; 264 } 265 266 x = x->subst(); 267 y = y->subst(); 268 269 Constant* y_const = y->as_Constant(); 270 if (y_const != NULL) { 271 IfOp* x_ifop = x->as_IfOp(); 272 if (x_ifop != NULL) { // x is an ifop, y is a constant 273 Constant* x_tval_const = x_ifop->tval()->subst()->as_Constant(); 274 Constant* x_fval_const = x_ifop->fval()->subst()->as_Constant(); 275 276 if (x_tval_const != NULL && x_fval_const != NULL) { 277 Instruction::Condition x_ifop_cond = x_ifop->cond(); 278 279 Constant::CompareResult t_compare_res = x_tval_const->compare(cond, y_const); 280 Constant::CompareResult f_compare_res = x_fval_const->compare(cond, y_const); 281 282 // not_comparable here is a valid return in case we're comparing unloaded oop constants 283 if (t_compare_res != Constant::not_comparable && f_compare_res != Constant::not_comparable) { 284 Value new_tval = t_compare_res == Constant::cond_true ? tval : fval; 285 Value new_fval = f_compare_res == Constant::cond_true ? tval : fval; 286 287 _ifop_count++; 288 if (new_tval == new_fval) { 289 return new_tval; 290 } else { 291 return new IfOp(x_ifop->x(), x_ifop_cond, x_ifop->y(), new_tval, new_fval); 292 } 293 } 294 } 295 } else { 296 Constant* x_const = x->as_Constant(); 297 if (x_const != NULL) { // x and y are constants 298 Constant::CompareResult x_compare_res = x_const->compare(cond, y_const); 299 // not_comparable here is a valid return in case we're comparing unloaded oop constants 300 if (x_compare_res != Constant::not_comparable) { 301 _ifop_count++; 302 return x_compare_res == Constant::cond_true ? tval : fval; 303 } 304 } 305 } 306 } 307 return new IfOp(x, cond, y, tval, fval); 308 } 309 310 void Optimizer::eliminate_conditional_expressions() { 311 // find conditional expressions & replace them with IfOps 312 CE_Eliminator ce(ir()); 313 } 314 315 class BlockMerger: public BlockClosure { 316 private: 317 IR* _hir; 318 int _merge_count; // the number of block pairs successfully merged 319 320 public: 321 BlockMerger(IR* hir) 322 : _hir(hir) 323 , _merge_count(0) 324 { 325 _hir->iterate_preorder(this); 326 CompileLog* log = _hir->compilation()->log(); 327 if (log != NULL) 328 log->set_context("optimize name='eliminate_blocks'"); 329 } 330 331 ~BlockMerger() { 332 CompileLog* log = _hir->compilation()->log(); 333 if (log != NULL) 334 log->clear_context(); // skip marker if nothing was printed 335 } 336 337 bool try_merge(BlockBegin* block) { 338 BlockEnd* end = block->end(); 339 if (end->as_Goto() != NULL) { 340 assert(end->number_of_sux() == 1, "end must have exactly one successor"); 341 // Note: It would be sufficient to check for the number of successors (= 1) 342 // in order to decide if this block can be merged potentially. That 343 // would then also include switch statements w/ only a default case. 344 // However, in that case we would need to make sure the switch tag 345 // expression is executed if it can produce observable side effects. 346 // We should probably have the canonicalizer simplifying such switch 347 // statements and then we are sure we don't miss these merge opportunities 348 // here (was bug - gri 7/7/99). 349 BlockBegin* sux = end->default_sux(); 350 if (sux->number_of_preds() == 1 && !sux->is_entry_block() && !end->is_safepoint()) { 351 // merge the two blocks 352 353 #ifdef ASSERT 354 // verify that state at the end of block and at the beginning of sux are equal 355 // no phi functions must be present at beginning of sux 356 ValueStack* sux_state = sux->state(); 357 ValueStack* end_state = end->state(); 358 359 assert(end_state->scope() == sux_state->scope(), "scopes must match"); 360 assert(end_state->stack_size() == sux_state->stack_size(), "stack not equal"); 361 assert(end_state->locals_size() == sux_state->locals_size(), "locals not equal"); 362 363 int index; 364 Value sux_value; 365 for_each_stack_value(sux_state, index, sux_value) { 366 assert(sux_value == end_state->stack_at(index), "stack not equal"); 367 } 368 for_each_local_value(sux_state, index, sux_value) { 369 assert(sux_value == end_state->local_at(index), "locals not equal"); 370 } 371 assert(sux_state->caller_state() == end_state->caller_state(), "caller not equal"); 372 #endif 373 374 // find instruction before end & append first instruction of sux block 375 Instruction* prev = end->prev(); 376 Instruction* next = sux->next(); 377 assert(prev->as_BlockEnd() == NULL, "must not be a BlockEnd"); 378 prev->set_next(next); 379 prev->fixup_block_pointers(); 380 sux->disconnect_from_graph(); 381 block->set_end(sux->end()); 382 // add exception handlers of deleted block, if any 383 for (int k = 0; k < sux->number_of_exception_handlers(); k++) { 384 BlockBegin* xhandler = sux->exception_handler_at(k); 385 block->add_exception_handler(xhandler); 386 387 // also substitute predecessor of exception handler 388 assert(xhandler->is_predecessor(sux), "missing predecessor"); 389 xhandler->remove_predecessor(sux); 390 if (!xhandler->is_predecessor(block)) { 391 xhandler->add_predecessor(block); 392 } 393 } 394 395 // debugging output 396 _merge_count++; 397 if (PrintBlockElimination) { 398 tty->print_cr("%d. merged B%d & B%d (stack size = %d)", 399 _merge_count, block->block_id(), sux->block_id(), sux->state()->stack_size()); 400 } 401 402 _hir->verify(); 403 404 If* if_ = block->end()->as_If(); 405 if (if_) { 406 IfOp* ifop = if_->x()->as_IfOp(); 407 Constant* con = if_->y()->as_Constant(); 408 bool swapped = false; 409 if (!con || !ifop) { 410 ifop = if_->y()->as_IfOp(); 411 con = if_->x()->as_Constant(); 412 swapped = true; 413 } 414 if (con && ifop) { 415 Constant* tval = ifop->tval()->as_Constant(); 416 Constant* fval = ifop->fval()->as_Constant(); 417 if (tval && fval) { 418 // Find the instruction before if_, starting with ifop. 419 // When if_ and ifop are not in the same block, prev 420 // becomes NULL In such (rare) cases it is not 421 // profitable to perform the optimization. 422 Value prev = ifop; 423 while (prev != NULL && prev->next() != if_) { 424 prev = prev->next(); 425 } 426 427 if (prev != NULL) { 428 Instruction::Condition cond = if_->cond(); 429 BlockBegin* tsux = if_->tsux(); 430 BlockBegin* fsux = if_->fsux(); 431 if (swapped) { 432 cond = Instruction::mirror(cond); 433 } 434 435 BlockBegin* tblock = tval->compare(cond, con, tsux, fsux); 436 BlockBegin* fblock = fval->compare(cond, con, tsux, fsux); 437 if (tblock != fblock && !if_->is_safepoint()) { 438 If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(), 439 tblock, fblock, if_->state_before(), if_->is_safepoint()); 440 newif->set_state(if_->state()->copy()); 441 442 assert(prev->next() == if_, "must be guaranteed by above search"); 443 NOT_PRODUCT(newif->set_printable_bci(if_->printable_bci())); 444 prev->set_next(newif); 445 block->set_end(newif); 446 447 _merge_count++; 448 if (PrintBlockElimination) { 449 tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id()); 450 } 451 452 _hir->verify(); 453 } 454 } 455 } 456 } 457 } 458 459 return true; 460 } 461 } 462 return false; 463 } 464 465 virtual void block_do(BlockBegin* block) { 466 _hir->verify(); 467 // repeat since the same block may merge again 468 while (try_merge(block)) { 469 _hir->verify(); 470 } 471 } 472 }; 473 474 475 void Optimizer::eliminate_blocks() { 476 // merge blocks if possible 477 BlockMerger bm(ir()); 478 } 479 480 481 class NullCheckEliminator; 482 class NullCheckVisitor: public InstructionVisitor { 483 private: 484 NullCheckEliminator* _nce; 485 NullCheckEliminator* nce() { return _nce; } 486 487 public: 488 NullCheckVisitor() {} 489 490 void set_eliminator(NullCheckEliminator* nce) { _nce = nce; } 491 492 void do_Phi (Phi* x); 493 void do_Local (Local* x); 494 void do_Constant (Constant* x); 495 void do_LoadField (LoadField* x); 496 void do_StoreField (StoreField* x); 497 void do_ArrayLength (ArrayLength* x); 498 void do_LoadIndexed (LoadIndexed* x); 499 void do_StoreIndexed (StoreIndexed* x); 500 void do_NegateOp (NegateOp* x); 501 void do_ArithmeticOp (ArithmeticOp* x); 502 void do_ShiftOp (ShiftOp* x); 503 void do_LogicOp (LogicOp* x); 504 void do_CompareOp (CompareOp* x); 505 void do_IfOp (IfOp* x); 506 void do_Convert (Convert* x); 507 void do_NullCheck (NullCheck* x); 508 void do_TypeCast (TypeCast* x); 509 void do_Invoke (Invoke* x); 510 void do_NewInstance (NewInstance* x); 511 void do_NewValueTypeInstance(NewValueTypeInstance* x); 512 void do_NewTypeArray (NewTypeArray* x); 513 void do_NewObjectArray (NewObjectArray* x); 514 void do_NewMultiArray (NewMultiArray* x); 515 void do_CheckCast (CheckCast* x); 516 void do_InstanceOf (InstanceOf* x); 517 void do_MonitorEnter (MonitorEnter* x); 518 void do_MonitorExit (MonitorExit* x); 519 void do_Intrinsic (Intrinsic* x); 520 void do_BlockBegin (BlockBegin* x); 521 void do_Goto (Goto* x); 522 void do_If (If* x); 523 void do_IfInstanceOf (IfInstanceOf* x); 524 void do_TableSwitch (TableSwitch* x); 525 void do_LookupSwitch (LookupSwitch* x); 526 void do_Return (Return* x); 527 void do_Throw (Throw* x); 528 void do_Base (Base* x); 529 void do_OsrEntry (OsrEntry* x); 530 void do_ExceptionObject(ExceptionObject* x); 531 void do_RoundFP (RoundFP* x); 532 void do_UnsafeGetRaw (UnsafeGetRaw* x); 533 void do_UnsafePutRaw (UnsafePutRaw* x); 534 void do_UnsafeGetObject(UnsafeGetObject* x); 535 void do_UnsafePutObject(UnsafePutObject* x); 536 void do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x); 537 void do_ProfileCall (ProfileCall* x); 538 void do_ProfileReturnType (ProfileReturnType* x); 539 void do_ProfileInvoke (ProfileInvoke* x); 540 void do_RuntimeCall (RuntimeCall* x); 541 void do_MemBar (MemBar* x); 542 void do_RangeCheckPredicate(RangeCheckPredicate* x); 543 #ifdef ASSERT 544 void do_Assert (Assert* x); 545 #endif 546 }; 547 548 549 // Because of a static contained within (for the purpose of iteration 550 // over instructions), it is only valid to have one of these active at 551 // a time 552 class NullCheckEliminator: public ValueVisitor { 553 private: 554 Optimizer* _opt; 555 556 ValueSet* _visitable_instructions; // Visit each instruction only once per basic block 557 BlockList* _work_list; // Basic blocks to visit 558 559 bool visitable(Value x) { 560 assert(_visitable_instructions != NULL, "check"); 561 return _visitable_instructions->contains(x); 562 } 563 void mark_visited(Value x) { 564 assert(_visitable_instructions != NULL, "check"); 565 _visitable_instructions->remove(x); 566 } 567 void mark_visitable(Value x) { 568 assert(_visitable_instructions != NULL, "check"); 569 _visitable_instructions->put(x); 570 } 571 void clear_visitable_state() { 572 assert(_visitable_instructions != NULL, "check"); 573 _visitable_instructions->clear(); 574 } 575 576 ValueSet* _set; // current state, propagated to subsequent BlockBegins 577 ValueSetList _block_states; // BlockBegin null-check states for all processed blocks 578 NullCheckVisitor _visitor; 579 NullCheck* _last_explicit_null_check; 580 581 bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); } 582 void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); } 583 void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); } 584 585 BlockList* work_list() { return _work_list; } 586 587 void iterate_all(); 588 void iterate_one(BlockBegin* block); 589 590 ValueSet* state() { return _set; } 591 void set_state_from (ValueSet* state) { _set->set_from(state); } 592 ValueSet* state_for (BlockBegin* block) { return _block_states.at(block->block_id()); } 593 void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states.at_put(block->block_id(), stack); } 594 // Returns true if caused a change in the block's state. 595 bool merge_state_for(BlockBegin* block, 596 ValueSet* incoming_state); 597 598 public: 599 // constructor 600 NullCheckEliminator(Optimizer* opt) 601 : _opt(opt) 602 , _work_list(new BlockList()) 603 , _set(new ValueSet()) 604 , _block_states(BlockBegin::number_of_blocks(), BlockBegin::number_of_blocks(), NULL) 605 , _last_explicit_null_check(NULL) { 606 _visitable_instructions = new ValueSet(); 607 _visitor.set_eliminator(this); 608 CompileLog* log = _opt->ir()->compilation()->log(); 609 if (log != NULL) 610 log->set_context("optimize name='null_check_elimination'"); 611 } 612 613 ~NullCheckEliminator() { 614 CompileLog* log = _opt->ir()->compilation()->log(); 615 if (log != NULL) 616 log->clear_context(); // skip marker if nothing was printed 617 } 618 619 Optimizer* opt() { return _opt; } 620 IR* ir () { return opt()->ir(); } 621 622 // Process a graph 623 void iterate(BlockBegin* root); 624 625 void visit(Value* f); 626 627 // In some situations (like NullCheck(x); getfield(x)) the debug 628 // information from the explicit NullCheck can be used to populate 629 // the getfield, even if the two instructions are in different 630 // scopes; this allows implicit null checks to be used but the 631 // correct exception information to be generated. We must clear the 632 // last-traversed NullCheck when we reach a potentially-exception- 633 // throwing instruction, as well as in some other cases. 634 void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; } 635 NullCheck* last_explicit_null_check() { return _last_explicit_null_check; } 636 Value last_explicit_null_check_obj() { return (_last_explicit_null_check 637 ? _last_explicit_null_check->obj() 638 : NULL); } 639 NullCheck* consume_last_explicit_null_check() { 640 _last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck); 641 _last_explicit_null_check->set_can_trap(false); 642 return _last_explicit_null_check; 643 } 644 void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; } 645 646 // Handlers for relevant instructions 647 // (separated out from NullCheckVisitor for clarity) 648 649 // The basic contract is that these must leave the instruction in 650 // the desired state; must not assume anything about the state of 651 // the instruction. We make multiple passes over some basic blocks 652 // and the last pass is the only one whose result is valid. 653 void handle_AccessField (AccessField* x); 654 void handle_ArrayLength (ArrayLength* x); 655 void handle_LoadIndexed (LoadIndexed* x); 656 void handle_StoreIndexed (StoreIndexed* x); 657 void handle_NullCheck (NullCheck* x); 658 void handle_Invoke (Invoke* x); 659 void handle_NewInstance (NewInstance* x); 660 void handle_NewValueTypeInstance(NewValueTypeInstance* x); 661 void handle_NewArray (NewArray* x); 662 void handle_AccessMonitor (AccessMonitor* x); 663 void handle_Intrinsic (Intrinsic* x); 664 void handle_ExceptionObject (ExceptionObject* x); 665 void handle_Phi (Phi* x); 666 void handle_ProfileCall (ProfileCall* x); 667 void handle_ProfileReturnType (ProfileReturnType* x); 668 }; 669 670 671 // NEEDS_CLEANUP 672 // There may be other instructions which need to clear the last 673 // explicit null check. Anything across which we can not hoist the 674 // debug information for a NullCheck instruction must clear it. It 675 // might be safer to pattern match "NullCheck ; {AccessField, 676 // ArrayLength, LoadIndexed}" but it is more easily structured this way. 677 // Should test to see performance hit of clearing it for all handlers 678 // with empty bodies below. If it is negligible then we should leave 679 // that in for safety, otherwise should think more about it. 680 void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); } 681 void NullCheckVisitor::do_Local (Local* x) {} 682 void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ } 683 void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); } 684 void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); } 685 void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); } 686 void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); } 687 void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); } 688 void NullCheckVisitor::do_NegateOp (NegateOp* x) {} 689 void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); } 690 void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {} 691 void NullCheckVisitor::do_LogicOp (LogicOp* x) {} 692 void NullCheckVisitor::do_CompareOp (CompareOp* x) {} 693 void NullCheckVisitor::do_IfOp (IfOp* x) {} 694 void NullCheckVisitor::do_Convert (Convert* x) {} 695 void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); } 696 void NullCheckVisitor::do_TypeCast (TypeCast* x) {} 697 void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); } 698 void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); } 699 void NullCheckVisitor::do_NewValueTypeInstance(NewValueTypeInstance* x) { nce()->handle_NewValueTypeInstance(x); } 700 void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); } 701 void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); } 702 void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); } 703 void NullCheckVisitor::do_CheckCast (CheckCast* x) { nce()->clear_last_explicit_null_check(); } 704 void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {} 705 void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); } 706 void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); } 707 void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->handle_Intrinsic(x); } 708 void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {} 709 void NullCheckVisitor::do_Goto (Goto* x) {} 710 void NullCheckVisitor::do_If (If* x) {} 711 void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {} 712 void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {} 713 void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {} 714 void NullCheckVisitor::do_Return (Return* x) {} 715 void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); } 716 void NullCheckVisitor::do_Base (Base* x) {} 717 void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {} 718 void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); } 719 void NullCheckVisitor::do_RoundFP (RoundFP* x) {} 720 void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {} 721 void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {} 722 void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {} 723 void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {} 724 void NullCheckVisitor::do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) {} 725 void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check(); 726 nce()->handle_ProfileCall(x); } 727 void NullCheckVisitor::do_ProfileReturnType (ProfileReturnType* x) { nce()->handle_ProfileReturnType(x); } 728 void NullCheckVisitor::do_ProfileInvoke (ProfileInvoke* x) {} 729 void NullCheckVisitor::do_RuntimeCall (RuntimeCall* x) {} 730 void NullCheckVisitor::do_MemBar (MemBar* x) {} 731 void NullCheckVisitor::do_RangeCheckPredicate(RangeCheckPredicate* x) {} 732 #ifdef ASSERT 733 void NullCheckVisitor::do_Assert (Assert* x) {} 734 #endif 735 736 void NullCheckEliminator::visit(Value* p) { 737 assert(*p != NULL, "should not find NULL instructions"); 738 if (visitable(*p)) { 739 mark_visited(*p); 740 (*p)->visit(&_visitor); 741 } 742 } 743 744 bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) { 745 ValueSet* state = state_for(block); 746 if (state == NULL) { 747 state = incoming_state->copy(); 748 set_state_for(block, state); 749 return true; 750 } else { 751 bool changed = state->set_intersect(incoming_state); 752 if (PrintNullCheckElimination && changed) { 753 tty->print_cr("Block %d's null check state changed", block->block_id()); 754 } 755 return changed; 756 } 757 } 758 759 760 void NullCheckEliminator::iterate_all() { 761 while (work_list()->length() > 0) { 762 iterate_one(work_list()->pop()); 763 } 764 } 765 766 767 void NullCheckEliminator::iterate_one(BlockBegin* block) { 768 clear_visitable_state(); 769 // clear out an old explicit null checks 770 set_last_explicit_null_check(NULL); 771 772 if (PrintNullCheckElimination) { 773 tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s", 774 block->block_id(), 775 ir()->method()->holder()->name()->as_utf8(), 776 ir()->method()->name()->as_utf8(), 777 ir()->method()->signature()->as_symbol()->as_utf8()); 778 } 779 780 // Create new state if none present (only happens at root) 781 if (state_for(block) == NULL) { 782 ValueSet* tmp_state = new ValueSet(); 783 set_state_for(block, tmp_state); 784 // Initial state is that local 0 (receiver) is non-null for 785 // non-static methods 786 ValueStack* stack = block->state(); 787 IRScope* scope = stack->scope(); 788 ciMethod* method = scope->method(); 789 if (!method->is_static()) { 790 Local* local0 = stack->local_at(0)->as_Local(); 791 assert(local0 != NULL, "must be"); 792 assert(local0->type() == objectType, "invalid type of receiver"); 793 794 if (local0 != NULL) { 795 // Local 0 is used in this scope 796 tmp_state->put(local0); 797 if (PrintNullCheckElimination) { 798 tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id()); 799 } 800 } 801 } 802 } 803 804 // Must copy block's state to avoid mutating it during iteration 805 // through the block -- otherwise "not-null" states can accidentally 806 // propagate "up" through the block during processing of backward 807 // branches and algorithm is incorrect (and does not converge) 808 set_state_from(state_for(block)); 809 810 // allow visiting of Phis belonging to this block 811 for_each_phi_fun(block, phi, 812 mark_visitable(phi); 813 ); 814 815 BlockEnd* e = block->end(); 816 assert(e != NULL, "incomplete graph"); 817 int i; 818 819 // Propagate the state before this block into the exception 820 // handlers. They aren't true successors since we aren't guaranteed 821 // to execute the whole block before executing them. Also putting 822 // them on first seems to help reduce the amount of iteration to 823 // reach a fixed point. 824 for (i = 0; i < block->number_of_exception_handlers(); i++) { 825 BlockBegin* next = block->exception_handler_at(i); 826 if (merge_state_for(next, state())) { 827 if (!work_list()->contains(next)) { 828 work_list()->push(next); 829 } 830 } 831 } 832 833 // Iterate through block, updating state. 834 for (Instruction* instr = block; instr != NULL; instr = instr->next()) { 835 // Mark instructions in this block as visitable as they are seen 836 // in the instruction list. This keeps the iteration from 837 // visiting instructions which are references in other blocks or 838 // visiting instructions more than once. 839 mark_visitable(instr); 840 if (instr->is_pinned() || instr->can_trap() || (instr->as_NullCheck() != NULL)) { 841 mark_visited(instr); 842 instr->input_values_do(this); 843 instr->visit(&_visitor); 844 } 845 } 846 847 // Propagate state to successors if necessary 848 for (i = 0; i < e->number_of_sux(); i++) { 849 BlockBegin* next = e->sux_at(i); 850 if (merge_state_for(next, state())) { 851 if (!work_list()->contains(next)) { 852 work_list()->push(next); 853 } 854 } 855 } 856 } 857 858 859 void NullCheckEliminator::iterate(BlockBegin* block) { 860 work_list()->push(block); 861 iterate_all(); 862 } 863 864 void NullCheckEliminator::handle_AccessField(AccessField* x) { 865 if (x->is_static()) { 866 if (x->as_LoadField() != NULL) { 867 // If the field is a non-null static final object field (as is 868 // often the case for sun.misc.Unsafe), put this LoadField into 869 // the non-null map 870 ciField* field = x->field(); 871 if (field->is_constant()) { 872 ciConstant field_val = field->constant_value(); 873 BasicType field_type = field_val.basic_type(); 874 if (field_type == T_OBJECT || field_type == T_ARRAY || field_type == T_VALUETYPE) { 875 ciObject* obj_val = field_val.as_object(); 876 if (!obj_val->is_null_object()) { 877 if (PrintNullCheckElimination) { 878 tty->print_cr("AccessField %d proven non-null by static final non-null oop check", 879 x->id()); 880 } 881 set_put(x); 882 } 883 } 884 } 885 } 886 // Be conservative 887 clear_last_explicit_null_check(); 888 return; 889 } 890 891 Value obj = x->obj(); 892 if (set_contains(obj)) { 893 // Value is non-null => update AccessField 894 if (last_explicit_null_check_obj() == obj && !x->needs_patching()) { 895 x->set_explicit_null_check(consume_last_explicit_null_check()); 896 x->set_needs_null_check(true); 897 if (PrintNullCheckElimination) { 898 tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d", 899 x->explicit_null_check()->id(), x->id(), obj->id()); 900 } 901 } else { 902 x->set_explicit_null_check(NULL); 903 x->set_needs_null_check(false); 904 if (PrintNullCheckElimination) { 905 tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id()); 906 } 907 } 908 } else { 909 set_put(obj); 910 if (PrintNullCheckElimination) { 911 tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id()); 912 } 913 // Ensure previous passes do not cause wrong state 914 x->set_needs_null_check(true); 915 x->set_explicit_null_check(NULL); 916 } 917 clear_last_explicit_null_check(); 918 } 919 920 921 void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) { 922 Value array = x->array(); 923 if (set_contains(array)) { 924 // Value is non-null => update AccessArray 925 if (last_explicit_null_check_obj() == array) { 926 x->set_explicit_null_check(consume_last_explicit_null_check()); 927 x->set_needs_null_check(true); 928 if (PrintNullCheckElimination) { 929 tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d", 930 x->explicit_null_check()->id(), x->id(), array->id()); 931 } 932 } else { 933 x->set_explicit_null_check(NULL); 934 x->set_needs_null_check(false); 935 if (PrintNullCheckElimination) { 936 tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id()); 937 } 938 } 939 } else { 940 set_put(array); 941 if (PrintNullCheckElimination) { 942 tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id()); 943 } 944 // Ensure previous passes do not cause wrong state 945 x->set_needs_null_check(true); 946 x->set_explicit_null_check(NULL); 947 } 948 clear_last_explicit_null_check(); 949 } 950 951 952 void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) { 953 Value array = x->array(); 954 if (set_contains(array)) { 955 // Value is non-null => update AccessArray 956 if (last_explicit_null_check_obj() == array) { 957 x->set_explicit_null_check(consume_last_explicit_null_check()); 958 x->set_needs_null_check(true); 959 if (PrintNullCheckElimination) { 960 tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d", 961 x->explicit_null_check()->id(), x->id(), array->id()); 962 } 963 } else { 964 x->set_explicit_null_check(NULL); 965 x->set_needs_null_check(false); 966 if (PrintNullCheckElimination) { 967 tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id()); 968 } 969 } 970 } else { 971 set_put(array); 972 if (PrintNullCheckElimination) { 973 tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id()); 974 } 975 // Ensure previous passes do not cause wrong state 976 x->set_needs_null_check(true); 977 x->set_explicit_null_check(NULL); 978 } 979 clear_last_explicit_null_check(); 980 } 981 982 983 void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) { 984 Value array = x->array(); 985 if (set_contains(array)) { 986 // Value is non-null => update AccessArray 987 if (PrintNullCheckElimination) { 988 tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id()); 989 } 990 x->set_needs_null_check(false); 991 } else { 992 set_put(array); 993 if (PrintNullCheckElimination) { 994 tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id()); 995 } 996 // Ensure previous passes do not cause wrong state 997 x->set_needs_null_check(true); 998 } 999 clear_last_explicit_null_check(); 1000 } 1001 1002 1003 void NullCheckEliminator::handle_NullCheck(NullCheck* x) { 1004 Value obj = x->obj(); 1005 if (set_contains(obj)) { 1006 // Already proven to be non-null => this NullCheck is useless 1007 if (PrintNullCheckElimination) { 1008 tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id()); 1009 } 1010 // Don't unpin since that may shrink obj's live range and make it unavailable for debug info. 1011 // The code generator won't emit LIR for a NullCheck that cannot trap. 1012 x->set_can_trap(false); 1013 } else { 1014 // May be null => add to map and set last explicit NullCheck 1015 x->set_can_trap(true); 1016 // make sure it's pinned if it can trap 1017 x->pin(Instruction::PinExplicitNullCheck); 1018 set_put(obj); 1019 set_last_explicit_null_check(x); 1020 if (PrintNullCheckElimination) { 1021 tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id()); 1022 } 1023 } 1024 } 1025 1026 1027 void NullCheckEliminator::handle_Invoke(Invoke* x) { 1028 if (!x->has_receiver()) { 1029 // Be conservative 1030 clear_last_explicit_null_check(); 1031 return; 1032 } 1033 1034 Value recv = x->receiver(); 1035 if (!set_contains(recv)) { 1036 set_put(recv); 1037 if (PrintNullCheckElimination) { 1038 tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id()); 1039 } 1040 } 1041 clear_last_explicit_null_check(); 1042 } 1043 1044 1045 void NullCheckEliminator::handle_NewInstance(NewInstance* x) { 1046 set_put(x); 1047 if (PrintNullCheckElimination) { 1048 tty->print_cr("NewInstance %d is non-null", x->id()); 1049 } 1050 } 1051 1052 void NullCheckEliminator::handle_NewValueTypeInstance(NewValueTypeInstance* x) { 1053 set_put(x); 1054 if (PrintNullCheckElimination) { 1055 tty->print_cr("NewValueTypeInstance %d is non-null", x->id()); 1056 } 1057 } 1058 1059 1060 void NullCheckEliminator::handle_NewArray(NewArray* x) { 1061 set_put(x); 1062 if (PrintNullCheckElimination) { 1063 tty->print_cr("NewArray %d is non-null", x->id()); 1064 } 1065 } 1066 1067 1068 void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) { 1069 set_put(x); 1070 if (PrintNullCheckElimination) { 1071 tty->print_cr("ExceptionObject %d is non-null", x->id()); 1072 } 1073 } 1074 1075 1076 void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) { 1077 Value obj = x->obj(); 1078 if (set_contains(obj)) { 1079 // Value is non-null => update AccessMonitor 1080 if (PrintNullCheckElimination) { 1081 tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id()); 1082 } 1083 x->set_needs_null_check(false); 1084 } else { 1085 set_put(obj); 1086 if (PrintNullCheckElimination) { 1087 tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id()); 1088 } 1089 // Ensure previous passes do not cause wrong state 1090 x->set_needs_null_check(true); 1091 } 1092 clear_last_explicit_null_check(); 1093 } 1094 1095 1096 void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) { 1097 if (!x->has_receiver()) { 1098 if (x->id() == vmIntrinsics::_arraycopy) { 1099 for (int i = 0; i < x->number_of_arguments(); i++) { 1100 x->set_arg_needs_null_check(i, !set_contains(x->argument_at(i))); 1101 } 1102 } 1103 1104 // Be conservative 1105 clear_last_explicit_null_check(); 1106 return; 1107 } 1108 1109 Value recv = x->receiver(); 1110 if (set_contains(recv)) { 1111 // Value is non-null => update Intrinsic 1112 if (PrintNullCheckElimination) { 1113 tty->print_cr("Eliminated Intrinsic %d's null check for value %d", x->id(), recv->id()); 1114 } 1115 x->set_needs_null_check(false); 1116 } else { 1117 set_put(recv); 1118 if (PrintNullCheckElimination) { 1119 tty->print_cr("Intrinsic %d of value %d proves value to be non-null", x->id(), recv->id()); 1120 } 1121 // Ensure previous passes do not cause wrong state 1122 x->set_needs_null_check(true); 1123 } 1124 clear_last_explicit_null_check(); 1125 } 1126 1127 1128 void NullCheckEliminator::handle_Phi(Phi* x) { 1129 int i; 1130 bool all_non_null = true; 1131 if (x->is_illegal()) { 1132 all_non_null = false; 1133 } else { 1134 for (i = 0; i < x->operand_count(); i++) { 1135 Value input = x->operand_at(i); 1136 if (!set_contains(input)) { 1137 all_non_null = false; 1138 } 1139 } 1140 } 1141 1142 if (all_non_null) { 1143 // Value is non-null => update Phi 1144 if (PrintNullCheckElimination) { 1145 tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id()); 1146 } 1147 x->set_needs_null_check(false); 1148 } else if (set_contains(x)) { 1149 set_remove(x); 1150 } 1151 } 1152 1153 void NullCheckEliminator::handle_ProfileCall(ProfileCall* x) { 1154 for (int i = 0; i < x->nb_profiled_args(); i++) { 1155 x->set_arg_needs_null_check(i, !set_contains(x->profiled_arg_at(i))); 1156 } 1157 } 1158 1159 void NullCheckEliminator::handle_ProfileReturnType(ProfileReturnType* x) { 1160 x->set_needs_null_check(!set_contains(x->ret())); 1161 } 1162 1163 void Optimizer::eliminate_null_checks() { 1164 ResourceMark rm; 1165 1166 NullCheckEliminator nce(this); 1167 1168 if (PrintNullCheckElimination) { 1169 tty->print_cr("Starting null check elimination for method %s::%s%s", 1170 ir()->method()->holder()->name()->as_utf8(), 1171 ir()->method()->name()->as_utf8(), 1172 ir()->method()->signature()->as_symbol()->as_utf8()); 1173 } 1174 1175 // Apply to graph 1176 nce.iterate(ir()->start()); 1177 1178 // walk over the graph looking for exception 1179 // handlers and iterate over them as well 1180 int nblocks = BlockBegin::number_of_blocks(); 1181 BlockList blocks(nblocks); 1182 boolArray visited_block(nblocks, nblocks, false); 1183 1184 blocks.push(ir()->start()); 1185 visited_block.at_put(ir()->start()->block_id(), true); 1186 for (int i = 0; i < blocks.length(); i++) { 1187 BlockBegin* b = blocks.at(i); 1188 // exception handlers need to be treated as additional roots 1189 for (int e = b->number_of_exception_handlers(); e-- > 0; ) { 1190 BlockBegin* excp = b->exception_handler_at(e); 1191 int id = excp->block_id(); 1192 if (!visited_block.at(id)) { 1193 blocks.push(excp); 1194 visited_block.at_put(id, true); 1195 nce.iterate(excp); 1196 } 1197 } 1198 // traverse successors 1199 BlockEnd *end = b->end(); 1200 for (int s = end->number_of_sux(); s-- > 0; ) { 1201 BlockBegin* next = end->sux_at(s); 1202 int id = next->block_id(); 1203 if (!visited_block.at(id)) { 1204 blocks.push(next); 1205 visited_block.at_put(id, true); 1206 } 1207 } 1208 } 1209 1210 1211 if (PrintNullCheckElimination) { 1212 tty->print_cr("Done with null check elimination for method %s::%s%s", 1213 ir()->method()->holder()->name()->as_utf8(), 1214 ir()->method()->name()->as_utf8(), 1215 ir()->method()->signature()->as_symbol()->as_utf8()); 1216 } 1217 }