1 /* 2 * Copyright (c) 1999, 2025, 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 "c1/c1_Compilation.hpp" 26 #include "c1/c1_FrameMap.hpp" 27 #include "c1/c1_GraphBuilder.hpp" 28 #include "c1/c1_IR.hpp" 29 #include "c1/c1_InstructionPrinter.hpp" 30 #include "c1/c1_Optimizer.hpp" 31 #include "compiler/oopMap.hpp" 32 #include "memory/resourceArea.hpp" 33 #include "utilities/bitMap.inline.hpp" 34 35 36 // Implementation of XHandlers 37 // 38 // Note: This code could eventually go away if we are 39 // just using the ciExceptionHandlerStream. 40 41 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) { 42 ciExceptionHandlerStream s(method); 43 while (!s.is_done()) { 44 _list.append(new XHandler(s.handler())); 45 s.next(); 46 } 47 assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent"); 48 } 49 50 // deep copy of all XHandler contained in list 51 XHandlers::XHandlers(XHandlers* other) : 52 _list(other->length()) 53 { 54 for (int i = 0; i < other->length(); i++) { 55 _list.append(new XHandler(other->handler_at(i))); 56 } 57 } 58 59 // Returns whether a particular exception type can be caught. Also 60 // returns true if klass is unloaded or any exception handler 61 // classes are unloaded. type_is_exact indicates whether the throw 62 // is known to be exactly that class or it might throw a subtype. 63 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const { 64 // the type is unknown so be conservative 65 if (!klass->is_loaded()) { 66 return true; 67 } 68 69 for (int i = 0; i < length(); i++) { 70 XHandler* handler = handler_at(i); 71 if (handler->is_catch_all()) { 72 // catch of ANY 73 return true; 74 } 75 ciInstanceKlass* handler_klass = handler->catch_klass(); 76 // if it's unknown it might be catchable 77 if (!handler_klass->is_loaded()) { 78 return true; 79 } 80 // if the throw type is definitely a subtype of the catch type 81 // then it can be caught. 82 if (klass->is_subtype_of(handler_klass)) { 83 return true; 84 } 85 if (!type_is_exact) { 86 // If the type isn't exactly known then it can also be caught by 87 // catch statements where the inexact type is a subtype of the 88 // catch type. 89 // given: foo extends bar extends Exception 90 // throw bar can be caught by catch foo, catch bar, and catch 91 // Exception, however it can't be caught by any handlers without 92 // bar in its type hierarchy. 93 if (handler_klass->is_subtype_of(klass)) { 94 return true; 95 } 96 } 97 } 98 99 return false; 100 } 101 102 103 bool XHandlers::equals(XHandlers* others) const { 104 if (others == nullptr) return false; 105 if (length() != others->length()) return false; 106 107 for (int i = 0; i < length(); i++) { 108 if (!handler_at(i)->equals(others->handler_at(i))) return false; 109 } 110 return true; 111 } 112 113 bool XHandler::equals(XHandler* other) const { 114 assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco"); 115 116 if (entry_pco() != other->entry_pco()) return false; 117 if (scope_count() != other->scope_count()) return false; 118 if (_desc != other->_desc) return false; 119 120 assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal"); 121 return true; 122 } 123 124 125 // Implementation of IRScope 126 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) { 127 GraphBuilder gm(compilation, this); 128 NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats()); 129 if (compilation->bailed_out()) return nullptr; 130 return gm.start(); 131 } 132 133 134 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph) 135 : _compilation(compilation) 136 , _callees(2) 137 , _requires_phi_function(method->max_locals()) 138 { 139 _caller = caller; 140 _level = caller == nullptr ? 0 : caller->level() + 1; 141 _method = method; 142 _xhandlers = new XHandlers(method); 143 _number_of_locks = 0; 144 _monitor_pairing_ok = method->has_balanced_monitors(); 145 _wrote_final = false; 146 _wrote_fields = false; 147 _wrote_volatile = false; 148 _wrote_stable = false; 149 _start = nullptr; 150 151 if (osr_bci != -1) { 152 // selective creation of phi functions is not possibel in osr-methods 153 _requires_phi_function.set_range(0, method->max_locals()); 154 } 155 156 assert(method->holder()->is_loaded() , "method holder must be loaded"); 157 158 // build graph if monitor pairing is ok 159 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci); 160 } 161 162 163 int IRScope::max_stack() const { 164 int my_max = method()->max_stack(); 165 int callee_max = 0; 166 for (int i = 0; i < number_of_callees(); i++) { 167 callee_max = MAX2(callee_max, callee_no(i)->max_stack()); 168 } 169 return my_max + callee_max; 170 } 171 172 173 bool IRScopeDebugInfo::should_reexecute() { 174 ciMethod* cur_method = scope()->method(); 175 int cur_bci = bci(); 176 if (cur_method != nullptr && cur_bci != SynchronizationEntryBCI) { 177 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci); 178 return Interpreter::bytecode_should_reexecute(code); 179 } else 180 return false; 181 } 182 183 184 // Implementation of CodeEmitInfo 185 186 // Stack must be NON-null 187 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception) 188 : _scope_debug_info(nullptr) 189 , _scope(stack->scope()) 190 , _exception_handlers(exception_handlers) 191 , _oop_map(nullptr) 192 , _stack(stack) 193 , _is_method_handle_invoke(false) 194 , _deoptimize_on_exception(deoptimize_on_exception) 195 , _force_reexecute(false) { 196 assert(_stack != nullptr, "must be non null"); 197 } 198 199 200 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack) 201 : _scope_debug_info(nullptr) 202 , _scope(info->_scope) 203 , _exception_handlers(nullptr) 204 , _oop_map(nullptr) 205 , _stack(stack == nullptr ? info->_stack : stack) 206 , _is_method_handle_invoke(info->_is_method_handle_invoke) 207 , _deoptimize_on_exception(info->_deoptimize_on_exception) 208 , _force_reexecute(info->_force_reexecute) { 209 210 // deep copy of exception handlers 211 if (info->_exception_handlers != nullptr) { 212 _exception_handlers = new XHandlers(info->_exception_handlers); 213 } 214 } 215 216 217 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) { 218 // record the safepoint before recording the debug info for enclosing scopes 219 recorder->add_safepoint(pc_offset, _oop_map->deep_copy()); 220 bool reexecute = _force_reexecute || _scope_debug_info->should_reexecute(); 221 _scope_debug_info->record_debug_info(recorder, pc_offset, reexecute, _is_method_handle_invoke); 222 recorder->end_safepoint(pc_offset); 223 } 224 225 226 void CodeEmitInfo::add_register_oop(LIR_Opr opr) { 227 assert(_oop_map != nullptr, "oop map must already exist"); 228 assert(opr->is_single_cpu(), "should not call otherwise"); 229 230 VMReg name = frame_map()->regname(opr); 231 _oop_map->set_oop(name); 232 } 233 234 // Mirror the stack size calculation in the deopt code 235 // How much stack space would we need at this point in the program in 236 // case of deoptimization? 237 int CodeEmitInfo::interpreter_frame_size() const { 238 ValueStack* state = _stack; 239 int size = 0; 240 int callee_parameters = 0; 241 int callee_locals = 0; 242 int extra_args = state->scope()->method()->max_stack() - state->stack_size(); 243 244 while (state != nullptr) { 245 int locks = state->locks_size(); 246 int temps = state->stack_size(); 247 bool is_top_frame = (state == _stack); 248 ciMethod* method = state->scope()->method(); 249 250 int frame_size = BytesPerWord * Interpreter::size_activation(method->max_stack(), 251 temps + callee_parameters, 252 extra_args, 253 locks, 254 callee_parameters, 255 callee_locals, 256 is_top_frame); 257 size += frame_size; 258 259 callee_parameters = method->size_of_parameters(); 260 callee_locals = method->max_locals(); 261 extra_args = 0; 262 state = state->caller_state(); 263 } 264 return size + Deoptimization::last_frame_adjust(0, callee_locals) * BytesPerWord; 265 } 266 267 // Implementation of IR 268 269 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) : 270 _num_loops(0) { 271 // setup IR fields 272 _compilation = compilation; 273 _top_scope = new IRScope(compilation, nullptr, -1, method, osr_bci, true); 274 _code = nullptr; 275 } 276 277 278 void IR::optimize_blocks() { 279 Optimizer opt(this); 280 if (!compilation()->profile_branches()) { 281 if (DoCEE) { 282 opt.eliminate_conditional_expressions(); 283 #ifndef PRODUCT 284 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); } 285 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); } 286 #endif 287 } 288 if (EliminateBlocks) { 289 opt.eliminate_blocks(); 290 #ifndef PRODUCT 291 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); } 292 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); } 293 #endif 294 } 295 } 296 } 297 298 void IR::eliminate_null_checks() { 299 Optimizer opt(this); 300 if (EliminateNullChecks) { 301 opt.eliminate_null_checks(); 302 #ifndef PRODUCT 303 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); } 304 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); } 305 #endif 306 } 307 } 308 309 // The functionality of this class is to insert a new block between 310 // the 'from' and 'to' block of a critical edge. 311 // It first collects the block pairs, and then processes them. 312 // 313 // Some instructions may introduce more than one edge between two blocks. 314 // By checking if the current 'to' block sets critical_edge_split_flag 315 // (all new blocks set this flag) we can avoid repeated processing. 316 // This is why BlockPair contains the index rather than the original 'to' block. 317 class CriticalEdgeFinder: public BlockClosure { 318 BlockPairList blocks; 319 320 public: 321 CriticalEdgeFinder(IR* ir) { 322 ir->iterate_preorder(this); 323 } 324 325 void block_do(BlockBegin* bb) { 326 BlockEnd* be = bb->end(); 327 int nos = be->number_of_sux(); 328 if (nos >= 2) { 329 for (int i = 0; i < nos; i++) { 330 BlockBegin* sux = be->sux_at(i); 331 if (sux->number_of_preds() >= 2) { 332 blocks.append(new BlockPair(bb, i)); 333 } 334 } 335 } 336 } 337 338 void split_edges() { 339 for (int i = 0; i < blocks.length(); i++) { 340 BlockPair* pair = blocks.at(i); 341 BlockBegin* from = pair->from(); 342 int index = pair->index(); 343 BlockBegin* to = from->end()->sux_at(index); 344 if (to->is_set(BlockBegin::critical_edge_split_flag)) { 345 // inserted 346 continue; 347 } 348 BlockBegin* split = from->insert_block_between(to); 349 #ifndef PRODUCT 350 if ((PrintIR || PrintIR1) && Verbose) { 351 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)", 352 from->block_id(), to->block_id(), split->block_id()); 353 } 354 #endif 355 } 356 } 357 }; 358 359 void IR::split_critical_edges() { 360 CriticalEdgeFinder cef(this); 361 cef.split_edges(); 362 } 363 364 365 class UseCountComputer: public ValueVisitor, BlockClosure { 366 private: 367 void visit(Value* n) { 368 // Local instructions and Phis for expression stack values at the 369 // start of basic blocks are not added to the instruction list 370 if (!(*n)->is_linked() && (*n)->can_be_linked()) { 371 assert(false, "a node was not appended to the graph"); 372 Compilation::current()->bailout("a node was not appended to the graph"); 373 } 374 // use n's input if not visited before 375 if (!(*n)->is_pinned() && !(*n)->has_uses()) { 376 // note: a) if the instruction is pinned, it will be handled by compute_use_count 377 // b) if the instruction has uses, it was touched before 378 // => in both cases we don't need to update n's values 379 uses_do(n); 380 } 381 // use n 382 (*n)->_use_count++; 383 } 384 385 Values* worklist; 386 int depth; 387 enum { 388 max_recurse_depth = 20 389 }; 390 391 void uses_do(Value* n) { 392 depth++; 393 if (depth > max_recurse_depth) { 394 // don't allow the traversal to recurse too deeply 395 worklist->push(*n); 396 } else { 397 (*n)->input_values_do(this); 398 // special handling for some instructions 399 if ((*n)->as_BlockEnd() != nullptr) { 400 // note on BlockEnd: 401 // must 'use' the stack only if the method doesn't 402 // terminate, however, in those cases stack is empty 403 (*n)->state_values_do(this); 404 } 405 } 406 depth--; 407 } 408 409 void block_do(BlockBegin* b) { 410 depth = 0; 411 // process all pinned nodes as the roots of expression trees 412 for (Instruction* n = b; n != nullptr; n = n->next()) { 413 if (n->is_pinned()) uses_do(&n); 414 } 415 assert(depth == 0, "should have counted back down"); 416 417 // now process any unpinned nodes which recursed too deeply 418 while (worklist->length() > 0) { 419 Value t = worklist->pop(); 420 if (!t->is_pinned()) { 421 // compute the use count 422 uses_do(&t); 423 424 // pin the instruction so that LIRGenerator doesn't recurse 425 // too deeply during it's evaluation. 426 t->pin(); 427 } 428 } 429 assert(depth == 0, "should have counted back down"); 430 } 431 432 UseCountComputer() { 433 worklist = new Values(); 434 depth = 0; 435 } 436 437 public: 438 static void compute(BlockList* blocks) { 439 UseCountComputer ucc; 440 blocks->iterate_backward(&ucc); 441 } 442 }; 443 444 445 // helper macro for short definition of trace-output inside code 446 #ifdef ASSERT 447 #define TRACE_LINEAR_SCAN(level, code) \ 448 if (TraceLinearScanLevel >= level) { \ 449 code; \ 450 } 451 #else 452 #define TRACE_LINEAR_SCAN(level, code) 453 #endif 454 455 class ComputeLinearScanOrder : public StackObj { 456 private: 457 int _max_block_id; // the highest block_id of a block 458 int _num_blocks; // total number of blocks (smaller than _max_block_id) 459 int _num_loops; // total number of loops 460 bool _iterative_dominators;// method requires iterative computation of dominatiors 461 462 BlockList* _linear_scan_order; // the resulting list of blocks in correct order 463 464 ResourceBitMap _visited_blocks; // used for recursive processing of blocks 465 ResourceBitMap _active_blocks; // used for recursive processing of blocks 466 ResourceBitMap _dominator_blocks; // temporary BitMap used for computation of dominator 467 intArray _forward_branches; // number of incoming forward branches for each block 468 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges 469 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop 470 BlockList _work_list; // temporary list (used in mark_loops and compute_order) 471 BlockList _loop_headers; 472 473 Compilation* _compilation; 474 475 // accessors for _visited_blocks and _active_blocks 476 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); } 477 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); } 478 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); } 479 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); } 480 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); } 481 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); } 482 483 // accessors for _forward_branches 484 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); } 485 int dec_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) - 1); return _forward_branches.at(b->block_id()); } 486 487 // accessors for _loop_map 488 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); } 489 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); } 490 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); } 491 492 // count edges between blocks 493 void count_edges(BlockBegin* cur, BlockBegin* parent); 494 495 // loop detection 496 void mark_loops(); 497 void clear_non_natural_loops(BlockBegin* start_block); 498 void assign_loop_depth(BlockBegin* start_block); 499 500 // computation of final block order 501 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b); 502 void compute_dominator(BlockBegin* cur, BlockBegin* parent); 503 void compute_dominator_impl(BlockBegin* cur, BlockBegin* parent); 504 int compute_weight(BlockBegin* cur); 505 bool ready_for_processing(BlockBegin* cur); 506 void sort_into_work_list(BlockBegin* b); 507 void append_block(BlockBegin* cur); 508 void compute_order(BlockBegin* start_block); 509 510 // fixup of dominators for non-natural loops 511 bool compute_dominators_iter(); 512 void compute_dominators(); 513 514 // debug functions 515 DEBUG_ONLY(void print_blocks();) 516 DEBUG_ONLY(void verify();) 517 518 Compilation* compilation() const { return _compilation; } 519 public: 520 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block); 521 522 // accessors for final result 523 BlockList* linear_scan_order() const { return _linear_scan_order; } 524 int num_loops() const { return _num_loops; } 525 }; 526 527 528 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) : 529 _max_block_id(BlockBegin::number_of_blocks()), 530 _num_blocks(0), 531 _num_loops(0), 532 _iterative_dominators(false), 533 _linear_scan_order(nullptr), // initialized later with correct size 534 _visited_blocks(_max_block_id), 535 _active_blocks(_max_block_id), 536 _dominator_blocks(_max_block_id), 537 _forward_branches(_max_block_id, _max_block_id, 0), 538 _loop_end_blocks(8), 539 _loop_map(0), // initialized later with correct size 540 _work_list(8), 541 _compilation(c) 542 { 543 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order")); 544 545 count_edges(start_block, nullptr); 546 547 if (compilation()->is_profiling()) { 548 ciMethod *method = compilation()->method(); 549 if (!method->is_accessor()) { 550 ciMethodData* md = method->method_data_or_null(); 551 assert(md != nullptr, "Sanity"); 552 md->set_compilation_stats(_num_loops, _num_blocks); 553 } 554 } 555 556 if (_num_loops > 0) { 557 mark_loops(); 558 clear_non_natural_loops(start_block); 559 assign_loop_depth(start_block); 560 } 561 562 compute_order(start_block); 563 compute_dominators(); 564 565 DEBUG_ONLY(print_blocks()); 566 DEBUG_ONLY(verify()); 567 } 568 569 570 // Traverse the CFG: 571 // * count total number of blocks 572 // * count all incoming edges and backward incoming edges 573 // * number loop header blocks 574 // * create a list with all loop end blocks 575 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) { 576 TRACE_LINEAR_SCAN(3, tty->print_cr("Enter count_edges for block B%d coming from B%d", cur->block_id(), parent != nullptr ? parent->block_id() : -1)); 577 assert(cur->dominator() == nullptr, "dominator already initialized"); 578 579 if (is_active(cur)) { 580 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch")); 581 assert(is_visited(cur), "block must be visisted when block is active"); 582 assert(parent != nullptr, "must have parent"); 583 584 cur->set(BlockBegin::backward_branch_target_flag); 585 586 // When a loop header is also the start of an exception handler, then the backward branch is 587 // an exception edge. Because such edges are usually critical edges which cannot be split, the 588 // loop must be excluded here from processing. 589 if (cur->is_set(BlockBegin::exception_entry_flag)) { 590 // Make sure that dominators are correct in this weird situation 591 _iterative_dominators = true; 592 return; 593 } 594 595 cur->set(BlockBegin::linear_scan_loop_header_flag); 596 parent->set(BlockBegin::linear_scan_loop_end_flag); 597 598 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur, 599 "loop end blocks must have one successor (critical edges are split)"); 600 601 _loop_end_blocks.append(parent); 602 return; 603 } 604 605 // increment number of incoming forward branches 606 inc_forward_branches(cur); 607 608 if (is_visited(cur)) { 609 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited")); 610 return; 611 } 612 613 _num_blocks++; 614 set_visited(cur); 615 set_active(cur); 616 617 // recursive call for all successors 618 int i; 619 for (i = cur->number_of_sux() - 1; i >= 0; i--) { 620 count_edges(cur->sux_at(i), cur); 621 } 622 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) { 623 count_edges(cur->exception_handler_at(i), cur); 624 } 625 626 clear_active(cur); 627 628 // Each loop has a unique number. 629 // When multiple loops are nested, assign_loop_depth assumes that the 630 // innermost loop has the lowest number. This is guaranteed by setting 631 // the loop number after the recursive calls for the successors above 632 // have returned. 633 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) { 634 assert(cur->loop_index() == -1, "cannot set loop-index twice"); 635 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops)); 636 637 cur->set_loop_index(_num_loops); 638 _loop_headers.append(cur); 639 _num_loops++; 640 } 641 642 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id())); 643 } 644 645 646 void ComputeLinearScanOrder::mark_loops() { 647 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops")); 648 649 _loop_map = BitMap2D(_num_loops, _max_block_id); 650 651 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) { 652 BlockBegin* loop_end = _loop_end_blocks.at(i); 653 BlockBegin* loop_start = loop_end->sux_at(0); 654 int loop_idx = loop_start->loop_index(); 655 656 TRACE_LINEAR_SCAN(3, tty->print_cr("Processing loop from B%d to B%d (loop %d):", loop_start->block_id(), loop_end->block_id(), loop_idx)); 657 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set"); 658 assert(loop_end->number_of_sux() == 1, "incorrect number of successors"); 659 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set"); 660 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set"); 661 assert(_work_list.is_empty(), "work list must be empty before processing"); 662 663 // add the end-block of the loop to the working list 664 _work_list.push(loop_end); 665 set_block_in_loop(loop_idx, loop_end); 666 do { 667 BlockBegin* cur = _work_list.pop(); 668 669 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id())); 670 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list"); 671 672 // recursive processing of all predecessors ends when start block of loop is reached 673 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) { 674 for (int j = cur->number_of_preds() - 1; j >= 0; j--) { 675 BlockBegin* pred = cur->pred_at(j); 676 677 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) { 678 // this predecessor has not been processed yet, so add it to work list 679 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id())); 680 _work_list.push(pred); 681 set_block_in_loop(loop_idx, pred); 682 } 683 } 684 } 685 } while (!_work_list.is_empty()); 686 } 687 } 688 689 690 // check for non-natural loops (loops where the loop header does not dominate 691 // all other loop blocks = loops with multiple entries). 692 // such loops are ignored 693 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) { 694 for (int i = _num_loops - 1; i >= 0; i--) { 695 if (is_block_in_loop(i, start_block)) { 696 // loop i contains the entry block of the method 697 // -> this is not a natural loop, so ignore it 698 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i)); 699 700 BlockBegin *loop_header = _loop_headers.at(i); 701 assert(loop_header->is_set(BlockBegin::linear_scan_loop_header_flag), "Must be loop header"); 702 703 for (int j = 0; j < loop_header->number_of_preds(); j++) { 704 BlockBegin *pred = loop_header->pred_at(j); 705 pred->clear(BlockBegin::linear_scan_loop_end_flag); 706 } 707 708 loop_header->clear(BlockBegin::linear_scan_loop_header_flag); 709 710 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) { 711 clear_block_in_loop(i, block_id); 712 } 713 _iterative_dominators = true; 714 } 715 } 716 } 717 718 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) { 719 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing loop-depth and weight")); 720 init_visited(); 721 722 assert(_work_list.is_empty(), "work list must be empty before processing"); 723 _work_list.append(start_block); 724 725 do { 726 BlockBegin* cur = _work_list.pop(); 727 728 if (!is_visited(cur)) { 729 set_visited(cur); 730 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id())); 731 732 // compute loop-depth and loop-index for the block 733 assert(cur->loop_depth() == 0, "cannot set loop-depth twice"); 734 int i; 735 int loop_depth = 0; 736 int min_loop_idx = -1; 737 for (i = _num_loops - 1; i >= 0; i--) { 738 if (is_block_in_loop(i, cur)) { 739 loop_depth++; 740 min_loop_idx = i; 741 } 742 } 743 cur->set_loop_depth(loop_depth); 744 cur->set_loop_index(min_loop_idx); 745 746 // append all unvisited successors to work list 747 for (i = cur->number_of_sux() - 1; i >= 0; i--) { 748 _work_list.append(cur->sux_at(i)); 749 } 750 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) { 751 _work_list.append(cur->exception_handler_at(i)); 752 } 753 } 754 } while (!_work_list.is_empty()); 755 } 756 757 758 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) { 759 assert(a != nullptr && b != nullptr, "must have input blocks"); 760 761 _dominator_blocks.clear(); 762 while (a != nullptr) { 763 _dominator_blocks.set_bit(a->block_id()); 764 assert(a->dominator() != nullptr || a == _linear_scan_order->at(0), "dominator must be initialized"); 765 a = a->dominator(); 766 } 767 while (b != nullptr && !_dominator_blocks.at(b->block_id())) { 768 assert(b->dominator() != nullptr || b == _linear_scan_order->at(0), "dominator must be initialized"); 769 b = b->dominator(); 770 } 771 772 assert(b != nullptr, "could not find dominator"); 773 return b; 774 } 775 776 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) { 777 init_visited(); 778 compute_dominator_impl(cur, parent); 779 } 780 781 void ComputeLinearScanOrder::compute_dominator_impl(BlockBegin* cur, BlockBegin* parent) { 782 // Mark as visited to avoid recursive calls with same parent 783 set_visited(cur); 784 785 if (cur->dominator() == nullptr) { 786 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id())); 787 cur->set_dominator(parent); 788 789 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) { 790 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: computing dominator of B%d: common dominator of B%d and B%d is B%d", cur->block_id(), parent->block_id(), cur->dominator()->block_id(), common_dominator(cur->dominator(), parent)->block_id())); 791 // Does not hold for exception blocks 792 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), ""); 793 cur->set_dominator(common_dominator(cur->dominator(), parent)); 794 } 795 796 // Additional edge to xhandler of all our successors 797 // range check elimination needs that the state at the end of a 798 // block be valid in every block it dominates so cur must dominate 799 // the exception handlers of its successors. 800 int num_cur_xhandler = cur->number_of_exception_handlers(); 801 for (int j = 0; j < num_cur_xhandler; j++) { 802 BlockBegin* xhandler = cur->exception_handler_at(j); 803 if (!is_visited(xhandler)) { 804 compute_dominator_impl(xhandler, parent); 805 } 806 } 807 } 808 809 810 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) { 811 BlockBegin* single_sux = nullptr; 812 if (cur->number_of_sux() == 1) { 813 single_sux = cur->sux_at(0); 814 } 815 816 // limit loop-depth to 15 bit (only for security reason, it will never be so big) 817 int weight = (cur->loop_depth() & 0x7FFF) << 16; 818 819 // general macro for short definition of weight flags 820 // the first instance of INC_WEIGHT_IF has the highest priority 821 int cur_bit = 15; 822 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--; 823 824 // this is necessary for the (very rare) case that two successive blocks have 825 // the same loop depth, but a different loop index (can happen for endless loops 826 // with exception handlers) 827 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag)); 828 829 // loop end blocks (blocks that end with a backward branch) are added 830 // after all other blocks of the loop. 831 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag)); 832 833 // critical edge split blocks are preferred because than they have a bigger 834 // proability to be completely empty 835 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag)); 836 837 // exceptions should not be thrown in normal control flow, so these blocks 838 // are added as late as possible 839 INC_WEIGHT_IF(cur->end()->as_Throw() == nullptr && (single_sux == nullptr || single_sux->end()->as_Throw() == nullptr)); 840 INC_WEIGHT_IF(cur->end()->as_Return() == nullptr && (single_sux == nullptr || single_sux->end()->as_Return() == nullptr)); 841 842 // exceptions handlers are added as late as possible 843 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag)); 844 845 // guarantee that weight is > 0 846 weight |= 1; 847 848 #undef INC_WEIGHT_IF 849 assert(cur_bit >= 0, "too many flags"); 850 assert(weight > 0, "weight cannot become negative"); 851 852 return weight; 853 } 854 855 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) { 856 // Discount the edge just traveled. 857 // When the number drops to zero, all forward branches were processed 858 if (dec_forward_branches(cur) != 0) { 859 return false; 860 } 861 862 assert(_linear_scan_order->find(cur) == -1, "block already processed (block can be ready only once)"); 863 assert(_work_list.find(cur) == -1, "block already in work-list (block can be ready only once)"); 864 return true; 865 } 866 867 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) { 868 assert(_work_list.find(cur) == -1, "block already in work list"); 869 870 int cur_weight = compute_weight(cur); 871 872 // the linear_scan_number is used to cache the weight of a block 873 cur->set_linear_scan_number(cur_weight); 874 875 #ifndef PRODUCT 876 if (StressLinearScan) { 877 _work_list.insert_before(0, cur); 878 return; 879 } 880 #endif 881 882 _work_list.append(nullptr); // provide space for new element 883 884 int insert_idx = _work_list.length() - 1; 885 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) { 886 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1)); 887 insert_idx--; 888 } 889 _work_list.at_put(insert_idx, cur); 890 891 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id())); 892 TRACE_LINEAR_SCAN(3, for (int i = 0; i < _work_list.length(); i++) tty->print_cr("%8d B%2d weight:%6x", i, _work_list.at(i)->block_id(), _work_list.at(i)->linear_scan_number())); 893 894 #ifdef ASSERT 895 for (int i = 0; i < _work_list.length(); i++) { 896 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set"); 897 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist"); 898 } 899 #endif 900 } 901 902 void ComputeLinearScanOrder::append_block(BlockBegin* cur) { 903 TRACE_LINEAR_SCAN(3, tty->print_cr("appending block B%d (weight 0x%6x) to linear-scan order", cur->block_id(), cur->linear_scan_number())); 904 assert(_linear_scan_order->find(cur) == -1, "cannot add the same block twice"); 905 906 // currently, the linear scan order and code emit order are equal. 907 // therefore the linear_scan_number and the weight of a block must also 908 // be equal. 909 cur->set_linear_scan_number(_linear_scan_order->length()); 910 _linear_scan_order->append(cur); 911 } 912 913 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) { 914 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order")); 915 916 // the start block is always the first block in the linear scan order 917 _linear_scan_order = new BlockList(_num_blocks); 918 append_block(start_block); 919 920 assert(start_block->end()->as_Base() != nullptr, "start block must end with Base-instruction"); 921 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry(); 922 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry(); 923 924 BlockBegin* sux_of_osr_entry = nullptr; 925 if (osr_entry != nullptr) { 926 // special handling for osr entry: 927 // ignore the edge between the osr entry and its successor for processing 928 // the osr entry block is added manually below 929 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor"); 930 assert(osr_entry->sux_at(0)->number_of_preds() >= 2, "successor of osr entry must have two predecessors (otherwise it is not present in normal control flow"); 931 932 sux_of_osr_entry = osr_entry->sux_at(0); 933 dec_forward_branches(sux_of_osr_entry); 934 935 compute_dominator(osr_entry, start_block); 936 _iterative_dominators = true; 937 } 938 compute_dominator(std_entry, start_block); 939 940 // start processing with standard entry block 941 assert(_work_list.is_empty(), "list must be empty before processing"); 942 943 if (ready_for_processing(std_entry)) { 944 sort_into_work_list(std_entry); 945 } else { 946 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)"); 947 } 948 949 do { 950 BlockBegin* cur = _work_list.pop(); 951 952 if (cur == sux_of_osr_entry) { 953 // the osr entry block is ignored in normal processing, it is never added to the 954 // work list. Instead, it is added as late as possible manually here. 955 append_block(osr_entry); 956 compute_dominator(cur, osr_entry); 957 } 958 append_block(cur); 959 960 int i; 961 int num_sux = cur->number_of_sux(); 962 // changed loop order to get "intuitive" order of if- and else-blocks 963 for (i = 0; i < num_sux; i++) { 964 BlockBegin* sux = cur->sux_at(i); 965 compute_dominator(sux, cur); 966 if (ready_for_processing(sux)) { 967 sort_into_work_list(sux); 968 } 969 } 970 num_sux = cur->number_of_exception_handlers(); 971 for (i = 0; i < num_sux; i++) { 972 BlockBegin* sux = cur->exception_handler_at(i); 973 if (ready_for_processing(sux)) { 974 sort_into_work_list(sux); 975 } 976 } 977 } while (_work_list.length() > 0); 978 } 979 980 981 bool ComputeLinearScanOrder::compute_dominators_iter() { 982 bool changed = false; 983 int num_blocks = _linear_scan_order->length(); 984 985 assert(_linear_scan_order->at(0)->dominator() == nullptr, "must not have dominator"); 986 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors"); 987 for (int i = 1; i < num_blocks; i++) { 988 BlockBegin* block = _linear_scan_order->at(i); 989 990 BlockBegin* dominator = block->pred_at(0); 991 int num_preds = block->number_of_preds(); 992 993 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id())); 994 995 for (int j = 0; j < num_preds; j++) { 996 997 BlockBegin *pred = block->pred_at(j); 998 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id())); 999 1000 if (block->is_set(BlockBegin::exception_entry_flag)) { 1001 dominator = common_dominator(dominator, pred); 1002 int num_pred_preds = pred->number_of_preds(); 1003 for (int k = 0; k < num_pred_preds; k++) { 1004 dominator = common_dominator(dominator, pred->pred_at(k)); 1005 } 1006 } else { 1007 dominator = common_dominator(dominator, pred); 1008 } 1009 } 1010 1011 if (dominator != block->dominator()) { 1012 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: updating dominator of B%d from B%d to B%d", block->block_id(), block->dominator()->block_id(), dominator->block_id())); 1013 1014 block->set_dominator(dominator); 1015 changed = true; 1016 } 1017 } 1018 return changed; 1019 } 1020 1021 void ComputeLinearScanOrder::compute_dominators() { 1022 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators)); 1023 1024 // iterative computation of dominators is only required for methods with non-natural loops 1025 // and OSR-methods. For all other methods, the dominators computed when generating the 1026 // linear scan block order are correct. 1027 if (_iterative_dominators) { 1028 do { 1029 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation")); 1030 } while (compute_dominators_iter()); 1031 } 1032 1033 // check that dominators are correct 1034 assert(!compute_dominators_iter(), "fix point not reached"); 1035 1036 // Add Blocks to dominates-Array 1037 int num_blocks = _linear_scan_order->length(); 1038 for (int i = 0; i < num_blocks; i++) { 1039 BlockBegin* block = _linear_scan_order->at(i); 1040 1041 BlockBegin *dom = block->dominator(); 1042 if (dom) { 1043 assert(dom->dominator_depth() != -1, "Dominator must have been visited before"); 1044 dom->dominates()->append(block); 1045 block->set_dominator_depth(dom->dominator_depth() + 1); 1046 } else { 1047 block->set_dominator_depth(0); 1048 } 1049 } 1050 } 1051 1052 1053 #ifdef ASSERT 1054 void ComputeLinearScanOrder::print_blocks() { 1055 if (TraceLinearScanLevel >= 2) { 1056 tty->print_cr("----- loop information:"); 1057 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) { 1058 BlockBegin* cur = _linear_scan_order->at(block_idx); 1059 1060 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id()); 1061 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) { 1062 tty->print ("%d ", is_block_in_loop(loop_idx, cur)); 1063 } 1064 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth()); 1065 } 1066 } 1067 1068 if (TraceLinearScanLevel >= 1) { 1069 tty->print_cr("----- linear-scan block order:"); 1070 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) { 1071 BlockBegin* cur = _linear_scan_order->at(block_idx); 1072 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth()); 1073 1074 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " "); 1075 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " "); 1076 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " "); 1077 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " "); 1078 1079 if (cur->dominator() != nullptr) { 1080 tty->print(" dom: B%d ", cur->dominator()->block_id()); 1081 } else { 1082 tty->print(" dom: null "); 1083 } 1084 1085 if (cur->number_of_preds() > 0) { 1086 tty->print(" preds: "); 1087 for (int j = 0; j < cur->number_of_preds(); j++) { 1088 BlockBegin* pred = cur->pred_at(j); 1089 tty->print("B%d ", pred->block_id()); 1090 } 1091 } 1092 if (cur->number_of_sux() > 0) { 1093 tty->print(" sux: "); 1094 for (int j = 0; j < cur->number_of_sux(); j++) { 1095 BlockBegin* sux = cur->sux_at(j); 1096 tty->print("B%d ", sux->block_id()); 1097 } 1098 } 1099 if (cur->number_of_exception_handlers() > 0) { 1100 tty->print(" ex: "); 1101 for (int j = 0; j < cur->number_of_exception_handlers(); j++) { 1102 BlockBegin* ex = cur->exception_handler_at(j); 1103 tty->print("B%d ", ex->block_id()); 1104 } 1105 } 1106 tty->cr(); 1107 } 1108 } 1109 } 1110 1111 void ComputeLinearScanOrder::verify() { 1112 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list"); 1113 1114 if (StressLinearScan) { 1115 // blocks are scrambled when StressLinearScan is used 1116 return; 1117 } 1118 1119 // check that all successors of a block have a higher linear-scan-number 1120 // and that all predecessors of a block have a lower linear-scan-number 1121 // (only backward branches of loops are ignored) 1122 int i; 1123 for (i = 0; i < _linear_scan_order->length(); i++) { 1124 BlockBegin* cur = _linear_scan_order->at(i); 1125 1126 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number"); 1127 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->find(cur), "incorrect linear_scan_number"); 1128 1129 int j; 1130 for (j = cur->number_of_sux() - 1; j >= 0; j--) { 1131 BlockBegin* sux = cur->sux_at(j); 1132 1133 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->find(sux), "incorrect linear_scan_number"); 1134 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) { 1135 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order"); 1136 } 1137 if (cur->loop_depth() == sux->loop_depth()) { 1138 assert(cur->loop_index() == sux->loop_index() || sux->is_set(BlockBegin::linear_scan_loop_header_flag), "successive blocks with same loop depth must have same loop index"); 1139 } 1140 } 1141 1142 for (j = cur->number_of_preds() - 1; j >= 0; j--) { 1143 BlockBegin* pred = cur->pred_at(j); 1144 1145 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->find(pred), "incorrect linear_scan_number"); 1146 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) { 1147 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order"); 1148 } 1149 if (cur->loop_depth() == pred->loop_depth()) { 1150 assert(cur->loop_index() == pred->loop_index() || cur->is_set(BlockBegin::linear_scan_loop_header_flag), "successive blocks with same loop depth must have same loop index"); 1151 } 1152 1153 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors"); 1154 } 1155 1156 // check dominator 1157 if (i == 0) { 1158 assert(cur->dominator() == nullptr, "first block has no dominator"); 1159 } else { 1160 assert(cur->dominator() != nullptr, "all but first block must have dominator"); 1161 } 1162 // Assertion does not hold for exception handlers 1163 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0) || cur->is_set(BlockBegin::exception_entry_flag), "Single predecessor must also be dominator"); 1164 } 1165 1166 // check that all loops are continuous 1167 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) { 1168 int block_idx = 0; 1169 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop"); 1170 1171 // skip blocks before the loop 1172 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) { 1173 block_idx++; 1174 } 1175 // skip blocks of loop 1176 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) { 1177 block_idx++; 1178 } 1179 // after the first non-loop block, there must not be another loop-block 1180 while (block_idx < _num_blocks) { 1181 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order"); 1182 block_idx++; 1183 } 1184 } 1185 } 1186 #endif // ASSERT 1187 1188 1189 void IR::compute_code() { 1190 assert(is_valid(), "IR must be valid"); 1191 1192 ComputeLinearScanOrder compute_order(compilation(), start()); 1193 _num_loops = compute_order.num_loops(); 1194 _code = compute_order.linear_scan_order(); 1195 } 1196 1197 1198 void IR::compute_use_counts() { 1199 // make sure all values coming out of this block get evaluated. 1200 int num_blocks = _code->length(); 1201 for (int i = 0; i < num_blocks; i++) { 1202 _code->at(i)->end()->state()->pin_stack_for_linear_scan(); 1203 } 1204 1205 // compute use counts 1206 UseCountComputer::compute(_code); 1207 } 1208 1209 1210 void IR::iterate_preorder(BlockClosure* closure) { 1211 assert(is_valid(), "IR must be valid"); 1212 start()->iterate_preorder(closure); 1213 } 1214 1215 1216 void IR::iterate_postorder(BlockClosure* closure) { 1217 assert(is_valid(), "IR must be valid"); 1218 start()->iterate_postorder(closure); 1219 } 1220 1221 void IR::iterate_linear_scan_order(BlockClosure* closure) { 1222 linear_scan_order()->iterate_forward(closure); 1223 } 1224 1225 1226 #ifndef PRODUCT 1227 class BlockPrinter: public BlockClosure { 1228 private: 1229 InstructionPrinter* _ip; 1230 bool _cfg_only; 1231 bool _live_only; 1232 1233 public: 1234 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) { 1235 _ip = ip; 1236 _cfg_only = cfg_only; 1237 _live_only = live_only; 1238 } 1239 1240 virtual void block_do(BlockBegin* block) { 1241 if (_cfg_only) { 1242 _ip->print_instr(block); tty->cr(); 1243 } else { 1244 block->print_block(*_ip, _live_only); 1245 } 1246 } 1247 }; 1248 1249 1250 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) { 1251 ttyLocker ttyl; 1252 InstructionPrinter ip(!cfg_only); 1253 BlockPrinter bp(&ip, cfg_only, live_only); 1254 start->iterate_preorder(&bp); 1255 tty->cr(); 1256 } 1257 1258 void IR::print(bool cfg_only, bool live_only) { 1259 if (is_valid()) { 1260 print(start(), cfg_only, live_only); 1261 } else { 1262 tty->print_cr("invalid IR"); 1263 } 1264 } 1265 #endif // PRODUCT 1266 1267 #ifdef ASSERT 1268 class EndNotNullValidator : public BlockClosure { 1269 public: 1270 virtual void block_do(BlockBegin* block) { 1271 assert(block->end() != nullptr, "Expect block end to exist."); 1272 } 1273 }; 1274 1275 class XentryFlagValidator : public BlockClosure { 1276 public: 1277 virtual void block_do(BlockBegin* block) { 1278 for (int i = 0; i < block->end()->number_of_sux(); i++) { 1279 assert(!block->end()->sux_at(i)->is_set(BlockBegin::exception_entry_flag), "must not be xhandler"); 1280 } 1281 for (int i = 0; i < block->number_of_exception_handlers(); i++) { 1282 assert(block->exception_handler_at(i)->is_set(BlockBegin::exception_entry_flag), "must be xhandler"); 1283 } 1284 } 1285 }; 1286 1287 typedef GrowableArray<BlockList*> BlockListList; 1288 1289 // Validation goals: 1290 // - code() length == blocks length 1291 // - code() contents == blocks content 1292 // - Each block's computed predecessors match sux lists (length) 1293 // - Each block's computed predecessors match sux lists (set content) 1294 class PredecessorAndCodeValidator : public BlockClosure { 1295 private: 1296 BlockListList* _predecessors; // Each index i will hold predecessors of block with id i 1297 BlockList* _blocks; 1298 1299 static int cmp(BlockBegin** a, BlockBegin** b) { 1300 return (*a)->block_id() - (*b)->block_id(); 1301 } 1302 1303 public: 1304 PredecessorAndCodeValidator(IR* hir) { 1305 ResourceMark rm; 1306 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), BlockBegin::number_of_blocks(), nullptr); 1307 _blocks = new BlockList(BlockBegin::number_of_blocks()); 1308 1309 hir->start()->iterate_preorder(this); 1310 if (hir->code() != nullptr) { 1311 assert(hir->code()->length() == _blocks->length(), "must match"); 1312 for (int i = 0; i < _blocks->length(); i++) { 1313 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists"); 1314 } 1315 } 1316 1317 for (int i = 0; i < _blocks->length(); i++) { 1318 BlockBegin* block = _blocks->at(i); 1319 verify_block_preds_against_collected_preds(block); 1320 } 1321 } 1322 1323 virtual void block_do(BlockBegin* block) { 1324 _blocks->append(block); 1325 collect_predecessors(block); 1326 } 1327 1328 private: 1329 void collect_predecessors(BlockBegin* block) { 1330 for (int i = 0; i < block->end()->number_of_sux(); i++) { 1331 collect_predecessor(block, block->end()->sux_at(i)); 1332 } 1333 for (int i = 0; i < block->number_of_exception_handlers(); i++) { 1334 collect_predecessor(block, block->exception_handler_at(i)); 1335 } 1336 } 1337 1338 void collect_predecessor(BlockBegin* const pred, const BlockBegin* sux) { 1339 BlockList* preds = _predecessors->at_grow(sux->block_id(), nullptr); 1340 if (preds == nullptr) { 1341 preds = new BlockList(); 1342 _predecessors->at_put(sux->block_id(), preds); 1343 } 1344 preds->append(pred); 1345 } 1346 1347 void verify_block_preds_against_collected_preds(const BlockBegin* block) const { 1348 BlockList* preds = _predecessors->at(block->block_id()); 1349 if (preds == nullptr) { 1350 assert(block->number_of_preds() == 0, "should be the same"); 1351 return; 1352 } 1353 assert(preds->length() == block->number_of_preds(), "should be the same"); 1354 1355 // clone the pred list so we can mutate it 1356 BlockList* pred_copy = new BlockList(); 1357 for (int j = 0; j < block->number_of_preds(); j++) { 1358 pred_copy->append(block->pred_at(j)); 1359 } 1360 // sort them in the same order 1361 preds->sort(cmp); 1362 pred_copy->sort(cmp); 1363 for (int j = 0; j < block->number_of_preds(); j++) { 1364 assert(preds->at(j) == pred_copy->at(j), "must match"); 1365 } 1366 } 1367 }; 1368 1369 class VerifyBlockBeginField : public BlockClosure { 1370 public: 1371 virtual void block_do(BlockBegin* block) { 1372 for (Instruction* cur = block; cur != nullptr; cur = cur->next()) { 1373 assert(cur->block() == block, "Block begin is not correct"); 1374 } 1375 } 1376 }; 1377 1378 class ValidateEdgeMutuality : public BlockClosure { 1379 public: 1380 virtual void block_do(BlockBegin* block) { 1381 for (int i = 0; i < block->end()->number_of_sux(); i++) { 1382 assert(block->end()->sux_at(i)->is_predecessor(block), "Block's successor should have it as predecessor"); 1383 } 1384 1385 for (int i = 0; i < block->number_of_exception_handlers(); i++) { 1386 assert(block->exception_handler_at(i)->is_predecessor(block), "Block's exception handler should have it as predecessor"); 1387 } 1388 1389 for (int i = 0; i < block->number_of_preds(); i++) { 1390 assert(block->pred_at(i) != nullptr, "Predecessor must exist"); 1391 assert(block->pred_at(i)->end() != nullptr, "Predecessor end must exist"); 1392 bool is_sux = block->pred_at(i)->end()->is_sux(block); 1393 bool is_xhandler = block->pred_at(i)->is_exception_handler(block); 1394 assert(is_sux || is_xhandler, "Block's predecessor should have it as successor or xhandler"); 1395 } 1396 } 1397 }; 1398 1399 void IR::expand_with_neighborhood(BlockList& blocks) { 1400 int original_size = blocks.length(); 1401 for (int h = 0; h < original_size; h++) { 1402 BlockBegin* block = blocks.at(h); 1403 1404 for (int i = 0; i < block->end()->number_of_sux(); i++) { 1405 if (!blocks.contains(block->end()->sux_at(i))) { 1406 blocks.append(block->end()->sux_at(i)); 1407 } 1408 } 1409 1410 for (int i = 0; i < block->number_of_preds(); i++) { 1411 if (!blocks.contains(block->pred_at(i))) { 1412 blocks.append(block->pred_at(i)); 1413 } 1414 } 1415 1416 for (int i = 0; i < block->number_of_exception_handlers(); i++) { 1417 if (!blocks.contains(block->exception_handler_at(i))) { 1418 blocks.append(block->exception_handler_at(i)); 1419 } 1420 } 1421 } 1422 } 1423 1424 void IR::verify_local(BlockList& blocks) { 1425 EndNotNullValidator ennv; 1426 blocks.iterate_forward(&ennv); 1427 1428 ValidateEdgeMutuality vem; 1429 blocks.iterate_forward(&vem); 1430 1431 VerifyBlockBeginField verifier; 1432 blocks.iterate_forward(&verifier); 1433 } 1434 1435 void IR::verify() { 1436 XentryFlagValidator xe; 1437 iterate_postorder(&xe); 1438 1439 PredecessorAndCodeValidator pv(this); 1440 1441 EndNotNullValidator ennv; 1442 iterate_postorder(&ennv); 1443 1444 ValidateEdgeMutuality vem; 1445 iterate_postorder(&vem); 1446 1447 VerifyBlockBeginField verifier; 1448 iterate_postorder(&verifier); 1449 } 1450 #endif // ASSERT 1451 1452 void SubstitutionResolver::visit(Value* v) { 1453 Value v0 = *v; 1454 if (v0) { 1455 Value vs = v0->subst(); 1456 if (vs != v0) { 1457 *v = v0->subst(); 1458 } 1459 } 1460 } 1461 1462 #ifdef ASSERT 1463 class SubstitutionChecker: public ValueVisitor { 1464 void visit(Value* v) { 1465 Value v0 = *v; 1466 if (v0) { 1467 Value vs = v0->subst(); 1468 assert(vs == v0, "missed substitution"); 1469 } 1470 } 1471 }; 1472 #endif 1473 1474 1475 void SubstitutionResolver::block_do(BlockBegin* block) { 1476 Instruction* last = nullptr; 1477 for (Instruction* n = block; n != nullptr;) { 1478 n->values_do(this); 1479 // need to remove this instruction from the instruction stream 1480 if (n->subst() != n) { 1481 guarantee(last != nullptr, "must have last"); 1482 last->set_next(n->next()); 1483 } else { 1484 last = n; 1485 } 1486 n = last->next(); 1487 } 1488 1489 #ifdef ASSERT 1490 SubstitutionChecker check_substitute; 1491 if (block->state()) block->state()->values_do(&check_substitute); 1492 block->block_values_do(&check_substitute); 1493 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute); 1494 #endif 1495 }