1 /* 2 * Copyright (c) 1999, 2024, 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_Compilation.hpp" 27 #include "c1/c1_FrameMap.hpp" 28 #include "c1/c1_GraphBuilder.hpp" 29 #include "c1/c1_IR.hpp" 30 #include "c1/c1_InstructionPrinter.hpp" 31 #include "c1/c1_Optimizer.hpp" 32 #include "compiler/oopMap.hpp" 33 #include "memory/resourceArea.hpp" 34 #include "utilities/bitMap.inline.hpp" 35 36 37 // Implementation of XHandlers 38 // 39 // Note: This code could eventually go away if we are 40 // just using the ciExceptionHandlerStream. 41 42 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) { 43 ciExceptionHandlerStream s(method); 44 while (!s.is_done()) { 45 _list.append(new XHandler(s.handler())); 46 s.next(); 47 } 48 assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent"); 49 } 50 51 // deep copy of all XHandler contained in list 52 XHandlers::XHandlers(XHandlers* other) : 53 _list(other->length()) 54 { 55 for (int i = 0; i < other->length(); i++) { 56 _list.append(new XHandler(other->handler_at(i))); 57 } 58 } 59 60 // Returns whether a particular exception type can be caught. Also 61 // returns true if klass is unloaded or any exception handler 62 // classes are unloaded. type_is_exact indicates whether the throw 63 // is known to be exactly that class or it might throw a subtype. 64 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const { 65 // the type is unknown so be conservative 66 if (!klass->is_loaded()) { 67 return true; 68 } 69 70 for (int i = 0; i < length(); i++) { 71 XHandler* handler = handler_at(i); 72 if (handler->is_catch_all()) { 73 // catch of ANY 74 return true; 75 } 76 ciInstanceKlass* handler_klass = handler->catch_klass(); 77 // if it's unknown it might be catchable 78 if (!handler_klass->is_loaded()) { 79 return true; 80 } 81 // if the throw type is definitely a subtype of the catch type 82 // then it can be caught. 83 if (klass->is_subtype_of(handler_klass)) { 84 return true; 85 } 86 if (!type_is_exact) { 87 // If the type isn't exactly known then it can also be caught by 88 // catch statements where the inexact type is a subtype of the 89 // catch type. 90 // given: foo extends bar extends Exception 91 // throw bar can be caught by catch foo, catch bar, and catch 92 // Exception, however it can't be caught by any handlers without 93 // bar in its type hierarchy. 94 if (handler_klass->is_subtype_of(klass)) { 95 return true; 96 } 97 } 98 } 99 100 return false; 101 } 102 103 104 bool XHandlers::equals(XHandlers* others) const { 105 if (others == nullptr) return false; 106 if (length() != others->length()) return false; 107 108 for (int i = 0; i < length(); i++) { 109 if (!handler_at(i)->equals(others->handler_at(i))) return false; 110 } 111 return true; 112 } 113 114 bool XHandler::equals(XHandler* other) const { 115 assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco"); 116 117 if (entry_pco() != other->entry_pco()) return false; 118 if (scope_count() != other->scope_count()) return false; 119 if (_desc != other->_desc) return false; 120 121 assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal"); 122 return true; 123 } 124 125 126 // Implementation of IRScope 127 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) { 128 GraphBuilder gm(compilation, this); 129 NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats()); 130 if (compilation->bailed_out()) return nullptr; 131 return gm.start(); 132 } 133 134 135 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph) 136 : _compilation(compilation) 137 , _callees(2) 138 , _requires_phi_function(method->max_locals()) 139 { 140 _caller = caller; 141 _level = caller == nullptr ? 0 : caller->level() + 1; 142 _method = method; 143 _xhandlers = new XHandlers(method); 144 _number_of_locks = 0; 145 _monitor_pairing_ok = method->has_balanced_monitors(); 146 _wrote_final = false; 147 _wrote_fields = false; 148 _wrote_volatile = 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 if (_should_reexecute) { 175 return true; 176 } 177 ciMethod* cur_method = scope()->method(); 178 int cur_bci = bci(); 179 if (cur_method != nullptr && cur_bci != SynchronizationEntryBCI) { 180 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci); 181 return Interpreter::bytecode_should_reexecute(code); 182 } else 183 return false; 184 } 185 186 // Implementation of CodeEmitInfo 187 188 // Stack must be NON-null 189 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception) 190 : _scope_debug_info(nullptr) 191 , _scope(stack->scope()) 192 , _exception_handlers(exception_handlers) 193 , _oop_map(nullptr) 194 , _stack(stack) 195 , _is_method_handle_invoke(false) 196 , _deoptimize_on_exception(deoptimize_on_exception) 197 , _force_reexecute(false) { 198 assert(_stack != nullptr, "must be non null"); 199 } 200 201 202 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack) 203 : _scope_debug_info(nullptr) 204 , _scope(info->_scope) 205 , _exception_handlers(nullptr) 206 , _oop_map(nullptr) 207 , _stack(stack == nullptr ? info->_stack : stack) 208 , _is_method_handle_invoke(info->_is_method_handle_invoke) 209 , _deoptimize_on_exception(info->_deoptimize_on_exception) 210 , _force_reexecute(info->_force_reexecute) { 211 212 // deep copy of exception handlers 213 if (info->_exception_handlers != nullptr) { 214 _exception_handlers = new XHandlers(info->_exception_handlers); 215 } 216 } 217 218 219 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset, bool maybe_return_as_fields) { 220 // record the safepoint before recording the debug info for enclosing scopes 221 recorder->add_safepoint(pc_offset, _oop_map->deep_copy()); 222 bool reexecute = _force_reexecute || _scope_debug_info->should_reexecute(); 223 _scope_debug_info->record_debug_info(recorder, pc_offset, reexecute, _is_method_handle_invoke, maybe_return_as_fields); 224 recorder->end_safepoint(pc_offset); 225 } 226 227 228 void CodeEmitInfo::add_register_oop(LIR_Opr opr) { 229 assert(_oop_map != nullptr, "oop map must already exist"); 230 assert(opr->is_single_cpu(), "should not call otherwise"); 231 232 VMReg name = frame_map()->regname(opr); 233 _oop_map->set_oop(name); 234 } 235 236 // Mirror the stack size calculation in the deopt code 237 // How much stack space would we need at this point in the program in 238 // case of deoptimization? 239 int CodeEmitInfo::interpreter_frame_size() const { 240 ValueStack* state = _stack; 241 int size = 0; 242 int callee_parameters = 0; 243 int callee_locals = 0; 244 int extra_args = state->scope()->method()->max_stack() - state->stack_size(); 245 246 while (state != nullptr) { 247 int locks = state->locks_size(); 248 int temps = state->stack_size(); 249 bool is_top_frame = (state == _stack); 250 ciMethod* method = state->scope()->method(); 251 252 int frame_size = BytesPerWord * Interpreter::size_activation(method->max_stack(), 253 temps + callee_parameters, 254 extra_args, 255 locks, 256 callee_parameters, 257 callee_locals, 258 is_top_frame); 259 size += frame_size; 260 261 callee_parameters = method->size_of_parameters(); 262 callee_locals = method->max_locals(); 263 extra_args = 0; 264 state = state->caller_state(); 265 } 266 return size + Deoptimization::last_frame_adjust(0, callee_locals) * BytesPerWord; 267 } 268 269 // Implementation of IR 270 271 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) : 272 _num_loops(0) { 273 // setup IR fields 274 _compilation = compilation; 275 _top_scope = new IRScope(compilation, nullptr, -1, method, osr_bci, true); 276 _code = nullptr; 277 } 278 279 280 void IR::optimize_blocks() { 281 Optimizer opt(this); 282 if (!compilation()->profile_branches()) { 283 if (DoCEE) { 284 opt.eliminate_conditional_expressions(); 285 #ifndef PRODUCT 286 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); } 287 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); } 288 #endif 289 } 290 if (EliminateBlocks) { 291 opt.eliminate_blocks(); 292 #ifndef PRODUCT 293 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); } 294 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); } 295 #endif 296 } 297 } 298 } 299 300 void IR::eliminate_null_checks() { 301 Optimizer opt(this); 302 if (EliminateNullChecks) { 303 opt.eliminate_null_checks(); 304 #ifndef PRODUCT 305 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); } 306 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); } 307 #endif 308 } 309 } 310 311 // The functionality of this class is to insert a new block between 312 // the 'from' and 'to' block of a critical edge. 313 // It first collects the block pairs, and then processes them. 314 // 315 // Some instructions may introduce more than one edge between two blocks. 316 // By checking if the current 'to' block sets critical_edge_split_flag 317 // (all new blocks set this flag) we can avoid repeated processing. 318 // This is why BlockPair contains the index rather than the original 'to' block. 319 class CriticalEdgeFinder: public BlockClosure { 320 BlockPairList blocks; 321 322 public: 323 CriticalEdgeFinder(IR* ir) { 324 ir->iterate_preorder(this); 325 } 326 327 void block_do(BlockBegin* bb) { 328 BlockEnd* be = bb->end(); 329 int nos = be->number_of_sux(); 330 if (nos >= 2) { 331 for (int i = 0; i < nos; i++) { 332 BlockBegin* sux = be->sux_at(i); 333 if (sux->number_of_preds() >= 2) { 334 blocks.append(new BlockPair(bb, i)); 335 } 336 } 337 } 338 } 339 340 void split_edges() { 341 for (int i = 0; i < blocks.length(); i++) { 342 BlockPair* pair = blocks.at(i); 343 BlockBegin* from = pair->from(); 344 int index = pair->index(); 345 BlockBegin* to = from->end()->sux_at(index); 346 if (to->is_set(BlockBegin::critical_edge_split_flag)) { 347 // inserted 348 continue; 349 } 350 BlockBegin* split = from->insert_block_between(to); 351 #ifndef PRODUCT 352 if ((PrintIR || PrintIR1) && Verbose) { 353 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)", 354 from->block_id(), to->block_id(), split->block_id()); 355 } 356 #endif 357 } 358 } 359 }; 360 361 void IR::split_critical_edges() { 362 CriticalEdgeFinder cef(this); 363 cef.split_edges(); 364 } 365 366 367 class UseCountComputer: public ValueVisitor, BlockClosure { 368 private: 369 void visit(Value* n) { 370 // Local instructions and Phis for expression stack values at the 371 // start of basic blocks are not added to the instruction list 372 if (!(*n)->is_linked() && (*n)->can_be_linked()) { 373 assert(false, "a node was not appended to the graph"); 374 Compilation::current()->bailout("a node was not appended to the graph"); 375 } 376 // use n's input if not visited before 377 if (!(*n)->is_pinned() && !(*n)->has_uses()) { 378 // note: a) if the instruction is pinned, it will be handled by compute_use_count 379 // b) if the instruction has uses, it was touched before 380 // => in both cases we don't need to update n's values 381 uses_do(n); 382 } 383 // use n 384 (*n)->_use_count++; 385 } 386 387 Values* worklist; 388 int depth; 389 enum { 390 max_recurse_depth = 20 391 }; 392 393 void uses_do(Value* n) { 394 depth++; 395 if (depth > max_recurse_depth) { 396 // don't allow the traversal to recurse too deeply 397 worklist->push(*n); 398 } else { 399 (*n)->input_values_do(this); 400 // special handling for some instructions 401 if ((*n)->as_BlockEnd() != nullptr) { 402 // note on BlockEnd: 403 // must 'use' the stack only if the method doesn't 404 // terminate, however, in those cases stack is empty 405 (*n)->state_values_do(this); 406 } 407 } 408 depth--; 409 } 410 411 void block_do(BlockBegin* b) { 412 depth = 0; 413 // process all pinned nodes as the roots of expression trees 414 for (Instruction* n = b; n != nullptr; n = n->next()) { 415 if (n->is_pinned()) uses_do(&n); 416 } 417 assert(depth == 0, "should have counted back down"); 418 419 // now process any unpinned nodes which recursed too deeply 420 while (worklist->length() > 0) { 421 Value t = worklist->pop(); 422 if (!t->is_pinned()) { 423 // compute the use count 424 uses_do(&t); 425 426 // pin the instruction so that LIRGenerator doesn't recurse 427 // too deeply during it's evaluation. 428 t->pin(); 429 } 430 } 431 assert(depth == 0, "should have counted back down"); 432 } 433 434 UseCountComputer() { 435 worklist = new Values(); 436 depth = 0; 437 } 438 439 public: 440 static void compute(BlockList* blocks) { 441 UseCountComputer ucc; 442 blocks->iterate_backward(&ucc); 443 } 444 }; 445 446 447 // helper macro for short definition of trace-output inside code 448 #ifdef ASSERT 449 #define TRACE_LINEAR_SCAN(level, code) \ 450 if (TraceLinearScanLevel >= level) { \ 451 code; \ 452 } 453 #else 454 #define TRACE_LINEAR_SCAN(level, code) 455 #endif 456 457 class ComputeLinearScanOrder : public StackObj { 458 private: 459 int _max_block_id; // the highest block_id of a block 460 int _num_blocks; // total number of blocks (smaller than _max_block_id) 461 int _num_loops; // total number of loops 462 bool _iterative_dominators;// method requires iterative computation of dominatiors 463 464 BlockList* _linear_scan_order; // the resulting list of blocks in correct order 465 466 ResourceBitMap _visited_blocks; // used for recursive processing of blocks 467 ResourceBitMap _active_blocks; // used for recursive processing of blocks 468 ResourceBitMap _dominator_blocks; // temporary BitMap used for computation of dominator 469 intArray _forward_branches; // number of incoming forward branches for each block 470 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges 471 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop 472 BlockList _work_list; // temporary list (used in mark_loops and compute_order) 473 BlockList _loop_headers; 474 475 Compilation* _compilation; 476 477 // accessors for _visited_blocks and _active_blocks 478 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); } 479 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); } 480 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); } 481 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); } 482 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); } 483 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); } 484 485 // accessors for _forward_branches 486 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); } 487 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()); } 488 489 // accessors for _loop_map 490 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); } 491 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); } 492 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); } 493 494 // count edges between blocks 495 void count_edges(BlockBegin* cur, BlockBegin* parent); 496 497 // loop detection 498 void mark_loops(); 499 void clear_non_natural_loops(BlockBegin* start_block); 500 void assign_loop_depth(BlockBegin* start_block); 501 502 // computation of final block order 503 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b); 504 void compute_dominator(BlockBegin* cur, BlockBegin* parent); 505 void compute_dominator_impl(BlockBegin* cur, BlockBegin* parent); 506 int compute_weight(BlockBegin* cur); 507 bool ready_for_processing(BlockBegin* cur); 508 void sort_into_work_list(BlockBegin* b); 509 void append_block(BlockBegin* cur); 510 void compute_order(BlockBegin* start_block); 511 512 // fixup of dominators for non-natural loops 513 bool compute_dominators_iter(); 514 void compute_dominators(); 515 516 // debug functions 517 DEBUG_ONLY(void print_blocks();) 518 DEBUG_ONLY(void verify();) 519 520 Compilation* compilation() const { return _compilation; } 521 public: 522 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block); 523 524 // accessors for final result 525 BlockList* linear_scan_order() const { return _linear_scan_order; } 526 int num_loops() const { return _num_loops; } 527 }; 528 529 530 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) : 531 _max_block_id(BlockBegin::number_of_blocks()), 532 _num_blocks(0), 533 _num_loops(0), 534 _iterative_dominators(false), 535 _linear_scan_order(nullptr), // initialized later with correct size 536 _visited_blocks(_max_block_id), 537 _active_blocks(_max_block_id), 538 _dominator_blocks(_max_block_id), 539 _forward_branches(_max_block_id, _max_block_id, 0), 540 _loop_end_blocks(8), 541 _loop_map(0), // initialized later with correct size 542 _work_list(8), 543 _compilation(c) 544 { 545 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order")); 546 547 count_edges(start_block, nullptr); 548 549 if (compilation()->is_profiling()) { 550 ciMethod *method = compilation()->method(); 551 if (!method->is_accessor()) { 552 ciMethodData* md = method->method_data_or_null(); 553 assert(md != nullptr, "Sanity"); 554 md->set_compilation_stats(_num_loops, _num_blocks); 555 } 556 } 557 558 if (_num_loops > 0) { 559 mark_loops(); 560 clear_non_natural_loops(start_block); 561 assign_loop_depth(start_block); 562 } 563 564 compute_order(start_block); 565 compute_dominators(); 566 567 DEBUG_ONLY(print_blocks()); 568 DEBUG_ONLY(verify()); 569 } 570 571 572 // Traverse the CFG: 573 // * count total number of blocks 574 // * count all incoming edges and backward incoming edges 575 // * number loop header blocks 576 // * create a list with all loop end blocks 577 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) { 578 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)); 579 assert(cur->dominator() == nullptr, "dominator already initialized"); 580 581 if (is_active(cur)) { 582 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch")); 583 assert(is_visited(cur), "block must be visisted when block is active"); 584 assert(parent != nullptr, "must have parent"); 585 586 cur->set(BlockBegin::backward_branch_target_flag); 587 588 // When a loop header is also the start of an exception handler, then the backward branch is 589 // an exception edge. Because such edges are usually critical edges which cannot be split, the 590 // loop must be excluded here from processing. 591 if (cur->is_set(BlockBegin::exception_entry_flag)) { 592 // Make sure that dominators are correct in this weird situation 593 _iterative_dominators = true; 594 return; 595 } 596 597 cur->set(BlockBegin::linear_scan_loop_header_flag); 598 parent->set(BlockBegin::linear_scan_loop_end_flag); 599 600 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur, 601 "loop end blocks must have one successor (critical edges are split)"); 602 603 _loop_end_blocks.append(parent); 604 return; 605 } 606 607 // increment number of incoming forward branches 608 inc_forward_branches(cur); 609 610 if (is_visited(cur)) { 611 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited")); 612 return; 613 } 614 615 _num_blocks++; 616 set_visited(cur); 617 set_active(cur); 618 619 // recursive call for all successors 620 int i; 621 for (i = cur->number_of_sux() - 1; i >= 0; i--) { 622 count_edges(cur->sux_at(i), cur); 623 } 624 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) { 625 count_edges(cur->exception_handler_at(i), cur); 626 } 627 628 clear_active(cur); 629 630 // Each loop has a unique number. 631 // When multiple loops are nested, assign_loop_depth assumes that the 632 // innermost loop has the lowest number. This is guaranteed by setting 633 // the loop number after the recursive calls for the successors above 634 // have returned. 635 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) { 636 assert(cur->loop_index() == -1, "cannot set loop-index twice"); 637 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops)); 638 639 cur->set_loop_index(_num_loops); 640 _loop_headers.append(cur); 641 _num_loops++; 642 } 643 644 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id())); 645 } 646 647 648 void ComputeLinearScanOrder::mark_loops() { 649 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops")); 650 651 _loop_map = BitMap2D(_num_loops, _max_block_id); 652 653 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) { 654 BlockBegin* loop_end = _loop_end_blocks.at(i); 655 BlockBegin* loop_start = loop_end->sux_at(0); 656 int loop_idx = loop_start->loop_index(); 657 658 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)); 659 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set"); 660 assert(loop_end->number_of_sux() == 1, "incorrect number of successors"); 661 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set"); 662 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set"); 663 assert(_work_list.is_empty(), "work list must be empty before processing"); 664 665 // add the end-block of the loop to the working list 666 _work_list.push(loop_end); 667 set_block_in_loop(loop_idx, loop_end); 668 do { 669 BlockBegin* cur = _work_list.pop(); 670 671 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id())); 672 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list"); 673 674 // recursive processing of all predecessors ends when start block of loop is reached 675 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) { 676 for (int j = cur->number_of_preds() - 1; j >= 0; j--) { 677 BlockBegin* pred = cur->pred_at(j); 678 679 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) { 680 // this predecessor has not been processed yet, so add it to work list 681 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id())); 682 _work_list.push(pred); 683 set_block_in_loop(loop_idx, pred); 684 } 685 } 686 } 687 } while (!_work_list.is_empty()); 688 } 689 } 690 691 692 // check for non-natural loops (loops where the loop header does not dominate 693 // all other loop blocks = loops with multiple entries). 694 // such loops are ignored 695 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) { 696 for (int i = _num_loops - 1; i >= 0; i--) { 697 if (is_block_in_loop(i, start_block)) { 698 // loop i contains the entry block of the method 699 // -> this is not a natural loop, so ignore it 700 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i)); 701 702 BlockBegin *loop_header = _loop_headers.at(i); 703 assert(loop_header->is_set(BlockBegin::linear_scan_loop_header_flag), "Must be loop header"); 704 705 for (int j = 0; j < loop_header->number_of_preds(); j++) { 706 BlockBegin *pred = loop_header->pred_at(j); 707 pred->clear(BlockBegin::linear_scan_loop_end_flag); 708 } 709 710 loop_header->clear(BlockBegin::linear_scan_loop_header_flag); 711 712 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) { 713 clear_block_in_loop(i, block_id); 714 } 715 _iterative_dominators = true; 716 } 717 } 718 } 719 720 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) { 721 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing loop-depth and weight")); 722 init_visited(); 723 724 assert(_work_list.is_empty(), "work list must be empty before processing"); 725 _work_list.append(start_block); 726 727 do { 728 BlockBegin* cur = _work_list.pop(); 729 730 if (!is_visited(cur)) { 731 set_visited(cur); 732 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id())); 733 734 // compute loop-depth and loop-index for the block 735 assert(cur->loop_depth() == 0, "cannot set loop-depth twice"); 736 int i; 737 int loop_depth = 0; 738 int min_loop_idx = -1; 739 for (i = _num_loops - 1; i >= 0; i--) { 740 if (is_block_in_loop(i, cur)) { 741 loop_depth++; 742 min_loop_idx = i; 743 } 744 } 745 cur->set_loop_depth(loop_depth); 746 cur->set_loop_index(min_loop_idx); 747 748 // append all unvisited successors to work list 749 for (i = cur->number_of_sux() - 1; i >= 0; i--) { 750 _work_list.append(cur->sux_at(i)); 751 } 752 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) { 753 _work_list.append(cur->exception_handler_at(i)); 754 } 755 } 756 } while (!_work_list.is_empty()); 757 } 758 759 760 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) { 761 assert(a != nullptr && b != nullptr, "must have input blocks"); 762 763 _dominator_blocks.clear(); 764 while (a != nullptr) { 765 _dominator_blocks.set_bit(a->block_id()); 766 assert(a->dominator() != nullptr || a == _linear_scan_order->at(0), "dominator must be initialized"); 767 a = a->dominator(); 768 } 769 while (b != nullptr && !_dominator_blocks.at(b->block_id())) { 770 assert(b->dominator() != nullptr || b == _linear_scan_order->at(0), "dominator must be initialized"); 771 b = b->dominator(); 772 } 773 774 assert(b != nullptr, "could not find dominator"); 775 return b; 776 } 777 778 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) { 779 init_visited(); 780 compute_dominator_impl(cur, parent); 781 } 782 783 void ComputeLinearScanOrder::compute_dominator_impl(BlockBegin* cur, BlockBegin* parent) { 784 // Mark as visited to avoid recursive calls with same parent 785 set_visited(cur); 786 787 if (cur->dominator() == nullptr) { 788 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id())); 789 cur->set_dominator(parent); 790 791 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) { 792 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())); 793 // Does not hold for exception blocks 794 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), ""); 795 cur->set_dominator(common_dominator(cur->dominator(), parent)); 796 } 797 798 // Additional edge to xhandler of all our successors 799 // range check elimination needs that the state at the end of a 800 // block be valid in every block it dominates so cur must dominate 801 // the exception handlers of its successors. 802 int num_cur_xhandler = cur->number_of_exception_handlers(); 803 for (int j = 0; j < num_cur_xhandler; j++) { 804 BlockBegin* xhandler = cur->exception_handler_at(j); 805 if (!is_visited(xhandler)) { 806 compute_dominator_impl(xhandler, parent); 807 } 808 } 809 } 810 811 812 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) { 813 BlockBegin* single_sux = nullptr; 814 if (cur->number_of_sux() == 1) { 815 single_sux = cur->sux_at(0); 816 } 817 818 // limit loop-depth to 15 bit (only for security reason, it will never be so big) 819 int weight = (cur->loop_depth() & 0x7FFF) << 16; 820 821 // general macro for short definition of weight flags 822 // the first instance of INC_WEIGHT_IF has the highest priority 823 int cur_bit = 15; 824 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--; 825 826 // this is necessary for the (very rare) case that two successive blocks have 827 // the same loop depth, but a different loop index (can happen for endless loops 828 // with exception handlers) 829 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag)); 830 831 // loop end blocks (blocks that end with a backward branch) are added 832 // after all other blocks of the loop. 833 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag)); 834 835 // critical edge split blocks are preferred because than they have a bigger 836 // proability to be completely empty 837 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag)); 838 839 // exceptions should not be thrown in normal control flow, so these blocks 840 // are added as late as possible 841 INC_WEIGHT_IF(cur->end()->as_Throw() == nullptr && (single_sux == nullptr || single_sux->end()->as_Throw() == nullptr)); 842 INC_WEIGHT_IF(cur->end()->as_Return() == nullptr && (single_sux == nullptr || single_sux->end()->as_Return() == nullptr)); 843 844 // exceptions handlers are added as late as possible 845 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag)); 846 847 // guarantee that weight is > 0 848 weight |= 1; 849 850 #undef INC_WEIGHT_IF 851 assert(cur_bit >= 0, "too many flags"); 852 assert(weight > 0, "weight cannot become negative"); 853 854 return weight; 855 } 856 857 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) { 858 // Discount the edge just traveled. 859 // When the number drops to zero, all forward branches were processed 860 if (dec_forward_branches(cur) != 0) { 861 return false; 862 } 863 864 assert(_linear_scan_order->find(cur) == -1, "block already processed (block can be ready only once)"); 865 assert(_work_list.find(cur) == -1, "block already in work-list (block can be ready only once)"); 866 return true; 867 } 868 869 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) { 870 assert(_work_list.find(cur) == -1, "block already in work list"); 871 872 int cur_weight = compute_weight(cur); 873 874 // the linear_scan_number is used to cache the weight of a block 875 cur->set_linear_scan_number(cur_weight); 876 877 #ifndef PRODUCT 878 if (StressLinearScan) { 879 _work_list.insert_before(0, cur); 880 return; 881 } 882 #endif 883 884 _work_list.append(nullptr); // provide space for new element 885 886 int insert_idx = _work_list.length() - 1; 887 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) { 888 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1)); 889 insert_idx--; 890 } 891 _work_list.at_put(insert_idx, cur); 892 893 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id())); 894 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())); 895 896 #ifdef ASSERT 897 for (int i = 0; i < _work_list.length(); i++) { 898 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set"); 899 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist"); 900 } 901 #endif 902 } 903 904 void ComputeLinearScanOrder::append_block(BlockBegin* cur) { 905 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())); 906 assert(_linear_scan_order->find(cur) == -1, "cannot add the same block twice"); 907 908 // currently, the linear scan order and code emit order are equal. 909 // therefore the linear_scan_number and the weight of a block must also 910 // be equal. 911 cur->set_linear_scan_number(_linear_scan_order->length()); 912 _linear_scan_order->append(cur); 913 } 914 915 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) { 916 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order")); 917 918 // the start block is always the first block in the linear scan order 919 _linear_scan_order = new BlockList(_num_blocks); 920 append_block(start_block); 921 922 assert(start_block->end()->as_Base() != nullptr, "start block must end with Base-instruction"); 923 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry(); 924 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry(); 925 926 BlockBegin* sux_of_osr_entry = nullptr; 927 if (osr_entry != nullptr) { 928 // special handling for osr entry: 929 // ignore the edge between the osr entry and its successor for processing 930 // the osr entry block is added manually below 931 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor"); 932 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"); 933 934 sux_of_osr_entry = osr_entry->sux_at(0); 935 dec_forward_branches(sux_of_osr_entry); 936 937 compute_dominator(osr_entry, start_block); 938 _iterative_dominators = true; 939 } 940 compute_dominator(std_entry, start_block); 941 942 // start processing with standard entry block 943 assert(_work_list.is_empty(), "list must be empty before processing"); 944 945 if (ready_for_processing(std_entry)) { 946 sort_into_work_list(std_entry); 947 } else { 948 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)"); 949 } 950 951 do { 952 BlockBegin* cur = _work_list.pop(); 953 954 if (cur == sux_of_osr_entry) { 955 // the osr entry block is ignored in normal processing, it is never added to the 956 // work list. Instead, it is added as late as possible manually here. 957 append_block(osr_entry); 958 compute_dominator(cur, osr_entry); 959 } 960 append_block(cur); 961 962 int i; 963 int num_sux = cur->number_of_sux(); 964 // changed loop order to get "intuitive" order of if- and else-blocks 965 for (i = 0; i < num_sux; i++) { 966 BlockBegin* sux = cur->sux_at(i); 967 compute_dominator(sux, cur); 968 if (ready_for_processing(sux)) { 969 sort_into_work_list(sux); 970 } 971 } 972 num_sux = cur->number_of_exception_handlers(); 973 for (i = 0; i < num_sux; i++) { 974 BlockBegin* sux = cur->exception_handler_at(i); 975 if (ready_for_processing(sux)) { 976 sort_into_work_list(sux); 977 } 978 } 979 } while (_work_list.length() > 0); 980 } 981 982 983 bool ComputeLinearScanOrder::compute_dominators_iter() { 984 bool changed = false; 985 int num_blocks = _linear_scan_order->length(); 986 987 assert(_linear_scan_order->at(0)->dominator() == nullptr, "must not have dominator"); 988 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors"); 989 for (int i = 1; i < num_blocks; i++) { 990 BlockBegin* block = _linear_scan_order->at(i); 991 992 BlockBegin* dominator = block->pred_at(0); 993 int num_preds = block->number_of_preds(); 994 995 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id())); 996 997 for (int j = 0; j < num_preds; j++) { 998 999 BlockBegin *pred = block->pred_at(j); 1000 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id())); 1001 1002 if (block->is_set(BlockBegin::exception_entry_flag)) { 1003 dominator = common_dominator(dominator, pred); 1004 int num_pred_preds = pred->number_of_preds(); 1005 for (int k = 0; k < num_pred_preds; k++) { 1006 dominator = common_dominator(dominator, pred->pred_at(k)); 1007 } 1008 } else { 1009 dominator = common_dominator(dominator, pred); 1010 } 1011 } 1012 1013 if (dominator != block->dominator()) { 1014 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())); 1015 1016 block->set_dominator(dominator); 1017 changed = true; 1018 } 1019 } 1020 return changed; 1021 } 1022 1023 void ComputeLinearScanOrder::compute_dominators() { 1024 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators)); 1025 1026 // iterative computation of dominators is only required for methods with non-natural loops 1027 // and OSR-methods. For all other methods, the dominators computed when generating the 1028 // linear scan block order are correct. 1029 if (_iterative_dominators) { 1030 do { 1031 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation")); 1032 } while (compute_dominators_iter()); 1033 } 1034 1035 // check that dominators are correct 1036 assert(!compute_dominators_iter(), "fix point not reached"); 1037 1038 // Add Blocks to dominates-Array 1039 int num_blocks = _linear_scan_order->length(); 1040 for (int i = 0; i < num_blocks; i++) { 1041 BlockBegin* block = _linear_scan_order->at(i); 1042 1043 BlockBegin *dom = block->dominator(); 1044 if (dom) { 1045 assert(dom->dominator_depth() != -1, "Dominator must have been visited before"); 1046 dom->dominates()->append(block); 1047 block->set_dominator_depth(dom->dominator_depth() + 1); 1048 } else { 1049 block->set_dominator_depth(0); 1050 } 1051 } 1052 } 1053 1054 1055 #ifdef ASSERT 1056 void ComputeLinearScanOrder::print_blocks() { 1057 if (TraceLinearScanLevel >= 2) { 1058 tty->print_cr("----- loop information:"); 1059 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) { 1060 BlockBegin* cur = _linear_scan_order->at(block_idx); 1061 1062 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id()); 1063 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) { 1064 tty->print ("%d ", is_block_in_loop(loop_idx, cur)); 1065 } 1066 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth()); 1067 } 1068 } 1069 1070 if (TraceLinearScanLevel >= 1) { 1071 tty->print_cr("----- linear-scan block order:"); 1072 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) { 1073 BlockBegin* cur = _linear_scan_order->at(block_idx); 1074 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth()); 1075 1076 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " "); 1077 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " "); 1078 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " "); 1079 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " "); 1080 1081 if (cur->dominator() != nullptr) { 1082 tty->print(" dom: B%d ", cur->dominator()->block_id()); 1083 } else { 1084 tty->print(" dom: null "); 1085 } 1086 1087 if (cur->number_of_preds() > 0) { 1088 tty->print(" preds: "); 1089 for (int j = 0; j < cur->number_of_preds(); j++) { 1090 BlockBegin* pred = cur->pred_at(j); 1091 tty->print("B%d ", pred->block_id()); 1092 } 1093 } 1094 if (cur->number_of_sux() > 0) { 1095 tty->print(" sux: "); 1096 for (int j = 0; j < cur->number_of_sux(); j++) { 1097 BlockBegin* sux = cur->sux_at(j); 1098 tty->print("B%d ", sux->block_id()); 1099 } 1100 } 1101 if (cur->number_of_exception_handlers() > 0) { 1102 tty->print(" ex: "); 1103 for (int j = 0; j < cur->number_of_exception_handlers(); j++) { 1104 BlockBegin* ex = cur->exception_handler_at(j); 1105 tty->print("B%d ", ex->block_id()); 1106 } 1107 } 1108 tty->cr(); 1109 } 1110 } 1111 } 1112 1113 void ComputeLinearScanOrder::verify() { 1114 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list"); 1115 1116 if (StressLinearScan) { 1117 // blocks are scrambled when StressLinearScan is used 1118 return; 1119 } 1120 1121 // check that all successors of a block have a higher linear-scan-number 1122 // and that all predecessors of a block have a lower linear-scan-number 1123 // (only backward branches of loops are ignored) 1124 int i; 1125 for (i = 0; i < _linear_scan_order->length(); i++) { 1126 BlockBegin* cur = _linear_scan_order->at(i); 1127 1128 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number"); 1129 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->find(cur), "incorrect linear_scan_number"); 1130 1131 int j; 1132 for (j = cur->number_of_sux() - 1; j >= 0; j--) { 1133 BlockBegin* sux = cur->sux_at(j); 1134 1135 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->find(sux), "incorrect linear_scan_number"); 1136 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) { 1137 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order"); 1138 } 1139 if (cur->loop_depth() == sux->loop_depth()) { 1140 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"); 1141 } 1142 } 1143 1144 for (j = cur->number_of_preds() - 1; j >= 0; j--) { 1145 BlockBegin* pred = cur->pred_at(j); 1146 1147 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->find(pred), "incorrect linear_scan_number"); 1148 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) { 1149 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order"); 1150 } 1151 if (cur->loop_depth() == pred->loop_depth()) { 1152 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"); 1153 } 1154 1155 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors"); 1156 } 1157 1158 // check dominator 1159 if (i == 0) { 1160 assert(cur->dominator() == nullptr, "first block has no dominator"); 1161 } else { 1162 assert(cur->dominator() != nullptr, "all but first block must have dominator"); 1163 } 1164 // Assertion does not hold for exception handlers 1165 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"); 1166 } 1167 1168 // check that all loops are continuous 1169 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) { 1170 int block_idx = 0; 1171 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop"); 1172 1173 // skip blocks before the loop 1174 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) { 1175 block_idx++; 1176 } 1177 // skip blocks of loop 1178 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) { 1179 block_idx++; 1180 } 1181 // after the first non-loop block, there must not be another loop-block 1182 while (block_idx < _num_blocks) { 1183 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order"); 1184 block_idx++; 1185 } 1186 } 1187 } 1188 #endif // ASSERT 1189 1190 1191 void IR::compute_code() { 1192 assert(is_valid(), "IR must be valid"); 1193 1194 ComputeLinearScanOrder compute_order(compilation(), start()); 1195 _num_loops = compute_order.num_loops(); 1196 _code = compute_order.linear_scan_order(); 1197 } 1198 1199 1200 void IR::compute_use_counts() { 1201 // make sure all values coming out of this block get evaluated. 1202 int num_blocks = _code->length(); 1203 for (int i = 0; i < num_blocks; i++) { 1204 _code->at(i)->end()->state()->pin_stack_for_linear_scan(); 1205 } 1206 1207 // compute use counts 1208 UseCountComputer::compute(_code); 1209 } 1210 1211 1212 void IR::iterate_preorder(BlockClosure* closure) { 1213 assert(is_valid(), "IR must be valid"); 1214 start()->iterate_preorder(closure); 1215 } 1216 1217 1218 void IR::iterate_postorder(BlockClosure* closure) { 1219 assert(is_valid(), "IR must be valid"); 1220 start()->iterate_postorder(closure); 1221 } 1222 1223 void IR::iterate_linear_scan_order(BlockClosure* closure) { 1224 linear_scan_order()->iterate_forward(closure); 1225 } 1226 1227 1228 #ifndef PRODUCT 1229 class BlockPrinter: public BlockClosure { 1230 private: 1231 InstructionPrinter* _ip; 1232 bool _cfg_only; 1233 bool _live_only; 1234 1235 public: 1236 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) { 1237 _ip = ip; 1238 _cfg_only = cfg_only; 1239 _live_only = live_only; 1240 } 1241 1242 virtual void block_do(BlockBegin* block) { 1243 if (_cfg_only) { 1244 _ip->print_instr(block); tty->cr(); 1245 } else { 1246 block->print_block(*_ip, _live_only); 1247 } 1248 } 1249 }; 1250 1251 1252 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) { 1253 ttyLocker ttyl; 1254 InstructionPrinter ip(!cfg_only); 1255 BlockPrinter bp(&ip, cfg_only, live_only); 1256 start->iterate_preorder(&bp); 1257 tty->cr(); 1258 } 1259 1260 void IR::print(bool cfg_only, bool live_only) { 1261 if (is_valid()) { 1262 print(start(), cfg_only, live_only); 1263 } else { 1264 tty->print_cr("invalid IR"); 1265 } 1266 } 1267 #endif // PRODUCT 1268 1269 #ifdef ASSERT 1270 class EndNotNullValidator : public BlockClosure { 1271 public: 1272 virtual void block_do(BlockBegin* block) { 1273 assert(block->end() != nullptr, "Expect block end to exist."); 1274 } 1275 }; 1276 1277 class XentryFlagValidator : public BlockClosure { 1278 public: 1279 virtual void block_do(BlockBegin* block) { 1280 for (int i = 0; i < block->end()->number_of_sux(); i++) { 1281 assert(!block->end()->sux_at(i)->is_set(BlockBegin::exception_entry_flag), "must not be xhandler"); 1282 } 1283 for (int i = 0; i < block->number_of_exception_handlers(); i++) { 1284 assert(block->exception_handler_at(i)->is_set(BlockBegin::exception_entry_flag), "must be xhandler"); 1285 } 1286 } 1287 }; 1288 1289 typedef GrowableArray<BlockList*> BlockListList; 1290 1291 // Validation goals: 1292 // - code() length == blocks length 1293 // - code() contents == blocks content 1294 // - Each block's computed predecessors match sux lists (length) 1295 // - Each block's computed predecessors match sux lists (set content) 1296 class PredecessorAndCodeValidator : public BlockClosure { 1297 private: 1298 BlockListList* _predecessors; // Each index i will hold predecessors of block with id i 1299 BlockList* _blocks; 1300 1301 static int cmp(BlockBegin** a, BlockBegin** b) { 1302 return (*a)->block_id() - (*b)->block_id(); 1303 } 1304 1305 public: 1306 PredecessorAndCodeValidator(IR* hir) { 1307 ResourceMark rm; 1308 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), BlockBegin::number_of_blocks(), nullptr); 1309 _blocks = new BlockList(BlockBegin::number_of_blocks()); 1310 1311 hir->start()->iterate_preorder(this); 1312 if (hir->code() != nullptr) { 1313 assert(hir->code()->length() == _blocks->length(), "must match"); 1314 for (int i = 0; i < _blocks->length(); i++) { 1315 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists"); 1316 } 1317 } 1318 1319 for (int i = 0; i < _blocks->length(); i++) { 1320 BlockBegin* block = _blocks->at(i); 1321 verify_block_preds_against_collected_preds(block); 1322 } 1323 } 1324 1325 virtual void block_do(BlockBegin* block) { 1326 _blocks->append(block); 1327 collect_predecessors(block); 1328 } 1329 1330 private: 1331 void collect_predecessors(BlockBegin* block) { 1332 for (int i = 0; i < block->end()->number_of_sux(); i++) { 1333 collect_predecessor(block, block->end()->sux_at(i)); 1334 } 1335 for (int i = 0; i < block->number_of_exception_handlers(); i++) { 1336 collect_predecessor(block, block->exception_handler_at(i)); 1337 } 1338 } 1339 1340 void collect_predecessor(BlockBegin* const pred, const BlockBegin* sux) { 1341 BlockList* preds = _predecessors->at_grow(sux->block_id(), nullptr); 1342 if (preds == nullptr) { 1343 preds = new BlockList(); 1344 _predecessors->at_put(sux->block_id(), preds); 1345 } 1346 preds->append(pred); 1347 } 1348 1349 void verify_block_preds_against_collected_preds(const BlockBegin* block) const { 1350 BlockList* preds = _predecessors->at(block->block_id()); 1351 if (preds == nullptr) { 1352 assert(block->number_of_preds() == 0, "should be the same"); 1353 return; 1354 } 1355 assert(preds->length() == block->number_of_preds(), "should be the same"); 1356 1357 // clone the pred list so we can mutate it 1358 BlockList* pred_copy = new BlockList(); 1359 for (int j = 0; j < block->number_of_preds(); j++) { 1360 pred_copy->append(block->pred_at(j)); 1361 } 1362 // sort them in the same order 1363 preds->sort(cmp); 1364 pred_copy->sort(cmp); 1365 for (int j = 0; j < block->number_of_preds(); j++) { 1366 assert(preds->at(j) == pred_copy->at(j), "must match"); 1367 } 1368 } 1369 }; 1370 1371 class VerifyBlockBeginField : public BlockClosure { 1372 public: 1373 virtual void block_do(BlockBegin* block) { 1374 for (Instruction* cur = block; cur != nullptr; cur = cur->next()) { 1375 assert(cur->block() == block, "Block begin is not correct"); 1376 } 1377 } 1378 }; 1379 1380 class ValidateEdgeMutuality : public BlockClosure { 1381 public: 1382 virtual void block_do(BlockBegin* block) { 1383 for (int i = 0; i < block->end()->number_of_sux(); i++) { 1384 assert(block->end()->sux_at(i)->is_predecessor(block), "Block's successor should have it as predecessor"); 1385 } 1386 1387 for (int i = 0; i < block->number_of_exception_handlers(); i++) { 1388 assert(block->exception_handler_at(i)->is_predecessor(block), "Block's exception handler should have it as predecessor"); 1389 } 1390 1391 for (int i = 0; i < block->number_of_preds(); i++) { 1392 assert(block->pred_at(i) != nullptr, "Predecessor must exist"); 1393 assert(block->pred_at(i)->end() != nullptr, "Predecessor end must exist"); 1394 bool is_sux = block->pred_at(i)->end()->is_sux(block); 1395 bool is_xhandler = block->pred_at(i)->is_exception_handler(block); 1396 assert(is_sux || is_xhandler, "Block's predecessor should have it as successor or xhandler"); 1397 } 1398 } 1399 }; 1400 1401 void IR::expand_with_neighborhood(BlockList& blocks) { 1402 int original_size = blocks.length(); 1403 for (int h = 0; h < original_size; h++) { 1404 BlockBegin* block = blocks.at(h); 1405 1406 for (int i = 0; i < block->end()->number_of_sux(); i++) { 1407 if (!blocks.contains(block->end()->sux_at(i))) { 1408 blocks.append(block->end()->sux_at(i)); 1409 } 1410 } 1411 1412 for (int i = 0; i < block->number_of_preds(); i++) { 1413 if (!blocks.contains(block->pred_at(i))) { 1414 blocks.append(block->pred_at(i)); 1415 } 1416 } 1417 1418 for (int i = 0; i < block->number_of_exception_handlers(); i++) { 1419 if (!blocks.contains(block->exception_handler_at(i))) { 1420 blocks.append(block->exception_handler_at(i)); 1421 } 1422 } 1423 } 1424 } 1425 1426 void IR::verify_local(BlockList& blocks) { 1427 EndNotNullValidator ennv; 1428 blocks.iterate_forward(&ennv); 1429 1430 ValidateEdgeMutuality vem; 1431 blocks.iterate_forward(&vem); 1432 1433 VerifyBlockBeginField verifier; 1434 blocks.iterate_forward(&verifier); 1435 } 1436 1437 void IR::verify() { 1438 XentryFlagValidator xe; 1439 iterate_postorder(&xe); 1440 1441 PredecessorAndCodeValidator pv(this); 1442 1443 EndNotNullValidator ennv; 1444 iterate_postorder(&ennv); 1445 1446 ValidateEdgeMutuality vem; 1447 iterate_postorder(&vem); 1448 1449 VerifyBlockBeginField verifier; 1450 iterate_postorder(&verifier); 1451 } 1452 #endif // ASSERT 1453 1454 void SubstitutionResolver::visit(Value* v) { 1455 Value v0 = *v; 1456 if (v0) { 1457 Value vs = v0->subst(); 1458 if (vs != v0) { 1459 *v = v0->subst(); 1460 } 1461 } 1462 } 1463 1464 #ifdef ASSERT 1465 class SubstitutionChecker: public ValueVisitor { 1466 void visit(Value* v) { 1467 Value v0 = *v; 1468 if (v0) { 1469 Value vs = v0->subst(); 1470 assert(vs == v0, "missed substitution"); 1471 } 1472 } 1473 }; 1474 #endif 1475 1476 1477 void SubstitutionResolver::block_do(BlockBegin* block) { 1478 Instruction* last = nullptr; 1479 for (Instruction* n = block; n != nullptr;) { 1480 n->values_do(this); 1481 // need to remove this instruction from the instruction stream 1482 if (n->subst() != n) { 1483 guarantee(last != nullptr, "must have last"); 1484 last->set_next(n->next()); 1485 } else { 1486 last = n; 1487 } 1488 n = last->next(); 1489 } 1490 1491 #ifdef ASSERT 1492 SubstitutionChecker check_substitute; 1493 if (block->state()) block->state()->values_do(&check_substitute); 1494 block->block_values_do(&check_substitute); 1495 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute); 1496 #endif 1497 }