1 /* 2 * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "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 "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 == NULL) 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 NULL; 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 : _callees(2) 136 , _compilation(compilation) 137 , _requires_phi_function(method->max_locals()) 138 { 139 _caller = caller; 140 _level = caller == NULL ? 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 _start = NULL; 149 150 if (osr_bci == -1) { 151 _requires_phi_function.clear(); 152 } else { 153 // selective creation of phi functions is not possibel in osr-methods 154 _requires_phi_function.set_range(0, method->max_locals()); 155 } 156 157 assert(method->holder()->is_loaded() , "method holder must be loaded"); 158 159 // build graph if monitor pairing is ok 160 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci); 161 } 162 163 164 int IRScope::max_stack() const { 165 int my_max = method()->max_stack(); 166 int callee_max = 0; 167 for (int i = 0; i < number_of_callees(); i++) { 168 callee_max = MAX2(callee_max, callee_no(i)->max_stack()); 169 } 170 return my_max + callee_max; 171 } 172 173 174 bool IRScopeDebugInfo::should_reexecute() { 175 ciMethod* cur_method = scope()->method(); 176 int cur_bci = bci(); 177 if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) { 178 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci); 179 return Interpreter::bytecode_should_reexecute(code); 180 } else 181 return false; 182 } 183 184 185 // Implementation of CodeEmitInfo 186 187 // Stack must be NON-null 188 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception) 189 : _scope(stack->scope()) 190 , _scope_debug_info(NULL) 191 , _oop_map(NULL) 192 , _stack(stack) 193 , _exception_handlers(exception_handlers) 194 , _is_method_handle_invoke(false) 195 , _deoptimize_on_exception(deoptimize_on_exception) { 196 assert(_stack != NULL, "must be non null"); 197 } 198 199 200 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack) 201 : _scope(info->_scope) 202 , _exception_handlers(NULL) 203 , _scope_debug_info(NULL) 204 , _oop_map(NULL) 205 , _stack(stack == NULL ? info->_stack : stack) 206 , _is_method_handle_invoke(info->_is_method_handle_invoke) 207 , _deoptimize_on_exception(info->_deoptimize_on_exception) { 208 209 // deep copy of exception handlers 210 if (info->_exception_handlers != NULL) { 211 _exception_handlers = new XHandlers(info->_exception_handlers); 212 } 213 } 214 215 216 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) { 217 // record the safepoint before recording the debug info for enclosing scopes 218 recorder->add_safepoint(pc_offset, _oop_map->deep_copy()); 219 _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke); 220 recorder->end_safepoint(pc_offset); 221 } 222 223 224 void CodeEmitInfo::add_register_oop(LIR_Opr opr) { 225 assert(_oop_map != NULL, "oop map must already exist"); 226 assert(opr->is_single_cpu(), "should not call otherwise"); 227 228 VMReg name = frame_map()->regname(opr); 229 _oop_map->set_oop(name); 230 } 231 232 // Mirror the stack size calculation in the deopt code 233 // How much stack space would we need at this point in the program in 234 // case of deoptimization? 235 int CodeEmitInfo::interpreter_frame_size() const { 236 ValueStack* state = _stack; 237 int size = 0; 238 int callee_parameters = 0; 239 int callee_locals = 0; 240 int extra_args = state->scope()->method()->max_stack() - state->stack_size(); 241 242 while (state != NULL) { 243 int locks = state->locks_size(); 244 int temps = state->stack_size(); 245 bool is_top_frame = (state == _stack); 246 ciMethod* method = state->scope()->method(); 247 248 int frame_size = BytesPerWord * Interpreter::size_activation(method->max_stack(), 249 temps + callee_parameters, 250 extra_args, 251 locks, 252 callee_parameters, 253 callee_locals, 254 is_top_frame); 255 size += frame_size; 256 257 callee_parameters = method->size_of_parameters(); 258 callee_locals = method->max_locals(); 259 extra_args = 0; 260 state = state->caller_state(); 261 } 262 return size + Deoptimization::last_frame_adjust(0, callee_locals) * BytesPerWord; 263 } 264 265 // Implementation of IR 266 267 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) : 268 _num_loops(0) { 269 // setup IR fields 270 _compilation = compilation; 271 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true); 272 _code = NULL; 273 } 274 275 276 void IR::optimize_blocks() { 277 Optimizer opt(this); 278 if (!compilation()->profile_branches()) { 279 if (DoCEE) { 280 opt.eliminate_conditional_expressions(); 281 #ifndef PRODUCT 282 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); } 283 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); } 284 #endif 285 } 286 if (EliminateBlocks) { 287 opt.eliminate_blocks(); 288 #ifndef PRODUCT 289 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); } 290 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); } 291 #endif 292 } 293 } 294 } 295 296 void IR::eliminate_null_checks() { 297 Optimizer opt(this); 298 if (EliminateNullChecks) { 299 opt.eliminate_null_checks(); 300 #ifndef PRODUCT 301 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); } 302 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); } 303 #endif 304 } 305 } 306 307 308 static int sort_pairs(BlockPair** a, BlockPair** b) { 309 if ((*a)->from() == (*b)->from()) { 310 return (*a)->to()->block_id() - (*b)->to()->block_id(); 311 } else { 312 return (*a)->from()->block_id() - (*b)->from()->block_id(); 313 } 314 } 315 316 317 class CriticalEdgeFinder: public BlockClosure { 318 BlockPairList blocks; 319 IR* _ir; 320 321 public: 322 CriticalEdgeFinder(IR* ir): _ir(ir) {} 323 void block_do(BlockBegin* bb) { 324 BlockEnd* be = bb->end(); 325 int nos = be->number_of_sux(); 326 if (nos >= 2) { 327 for (int i = 0; i < nos; i++) { 328 BlockBegin* sux = be->sux_at(i); 329 if (sux->number_of_preds() >= 2) { 330 blocks.append(new BlockPair(bb, sux)); 331 } 332 } 333 } 334 } 335 336 void split_edges() { 337 BlockPair* last_pair = NULL; 338 blocks.sort(sort_pairs); 339 for (int i = 0; i < blocks.length(); i++) { 340 BlockPair* pair = blocks.at(i); 341 if (last_pair != NULL && pair->is_same(last_pair)) continue; 342 BlockBegin* from = pair->from(); 343 BlockBegin* to = pair->to(); 344 BlockBegin* split = from->insert_block_between(to); 345 #ifndef PRODUCT 346 if ((PrintIR || PrintIR1) && Verbose) { 347 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)", 348 from->block_id(), to->block_id(), split->block_id()); 349 } 350 #endif 351 last_pair = pair; 352 } 353 } 354 }; 355 356 void IR::split_critical_edges() { 357 CriticalEdgeFinder cef(this); 358 359 iterate_preorder(&cef); 360 cef.split_edges(); 361 } 362 363 364 class UseCountComputer: public ValueVisitor, BlockClosure { 365 private: 366 void visit(Value* n) { 367 // Local instructions and Phis for expression stack values at the 368 // start of basic blocks are not added to the instruction list 369 if (!(*n)->is_linked() && (*n)->can_be_linked()) { 370 assert(false, "a node was not appended to the graph"); 371 Compilation::current()->bailout("a node was not appended to the graph"); 372 } 373 // use n's input if not visited before 374 if (!(*n)->is_pinned() && !(*n)->has_uses()) { 375 // note: a) if the instruction is pinned, it will be handled by compute_use_count 376 // b) if the instruction has uses, it was touched before 377 // => in both cases we don't need to update n's values 378 uses_do(n); 379 } 380 // use n 381 (*n)->_use_count++; 382 } 383 384 Values* worklist; 385 int depth; 386 enum { 387 max_recurse_depth = 20 388 }; 389 390 void uses_do(Value* n) { 391 depth++; 392 if (depth > max_recurse_depth) { 393 // don't allow the traversal to recurse too deeply 394 worklist->push(*n); 395 } else { 396 (*n)->input_values_do(this); 397 // special handling for some instructions 398 if ((*n)->as_BlockEnd() != NULL) { 399 // note on BlockEnd: 400 // must 'use' the stack only if the method doesn't 401 // terminate, however, in those cases stack is empty 402 (*n)->state_values_do(this); 403 } 404 } 405 depth--; 406 } 407 408 void block_do(BlockBegin* b) { 409 depth = 0; 410 // process all pinned nodes as the roots of expression trees 411 for (Instruction* n = b; n != NULL; n = n->next()) { 412 if (n->is_pinned()) uses_do(&n); 413 } 414 assert(depth == 0, "should have counted back down"); 415 416 // now process any unpinned nodes which recursed too deeply 417 while (worklist->length() > 0) { 418 Value t = worklist->pop(); 419 if (!t->is_pinned()) { 420 // compute the use count 421 uses_do(&t); 422 423 // pin the instruction so that LIRGenerator doesn't recurse 424 // too deeply during it's evaluation. 425 t->pin(); 426 } 427 } 428 assert(depth == 0, "should have counted back down"); 429 } 430 431 UseCountComputer() { 432 worklist = new Values(); 433 depth = 0; 434 } 435 436 public: 437 static void compute(BlockList* blocks) { 438 UseCountComputer ucc; 439 blocks->iterate_backward(&ucc); 440 } 441 }; 442 443 444 // helper macro for short definition of trace-output inside code 445 #ifndef PRODUCT 446 #define TRACE_LINEAR_SCAN(level, code) \ 447 if (TraceLinearScanLevel >= level) { \ 448 code; \ 449 } 450 #else 451 #define TRACE_LINEAR_SCAN(level, code) 452 #endif 453 454 class ComputeLinearScanOrder : public StackObj { 455 private: 456 int _max_block_id; // the highest block_id of a block 457 int _num_blocks; // total number of blocks (smaller than _max_block_id) 458 int _num_loops; // total number of loops 459 bool _iterative_dominators;// method requires iterative computation of dominatiors 460 461 BlockList* _linear_scan_order; // the resulting list of blocks in correct order 462 463 BitMap _visited_blocks; // used for recursive processing of blocks 464 BitMap _active_blocks; // used for recursive processing of blocks 465 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator 466 intArray _forward_branches; // number of incoming forward branches for each block 467 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges 468 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop 469 BlockList _work_list; // temporary list (used in mark_loops and compute_order) 470 BlockList _loop_headers; 471 472 Compilation* _compilation; 473 474 // accessors for _visited_blocks and _active_blocks 475 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); } 476 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); } 477 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); } 478 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); } 479 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); } 480 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); } 481 482 // accessors for _forward_branches 483 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); } 484 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()); } 485 486 // accessors for _loop_map 487 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); } 488 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); } 489 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); } 490 491 // count edges between blocks 492 void count_edges(BlockBegin* cur, BlockBegin* parent); 493 494 // loop detection 495 void mark_loops(); 496 void clear_non_natural_loops(BlockBegin* start_block); 497 void assign_loop_depth(BlockBegin* start_block); 498 499 // computation of final block order 500 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b); 501 void compute_dominator(BlockBegin* cur, BlockBegin* parent); 502 int compute_weight(BlockBegin* cur); 503 bool ready_for_processing(BlockBegin* cur); 504 void sort_into_work_list(BlockBegin* b); 505 void append_block(BlockBegin* cur); 506 void compute_order(BlockBegin* start_block); 507 508 // fixup of dominators for non-natural loops 509 bool compute_dominators_iter(); 510 void compute_dominators(); 511 512 // debug functions 513 NOT_PRODUCT(void print_blocks();) 514 DEBUG_ONLY(void verify();) 515 516 Compilation* compilation() const { return _compilation; } 517 public: 518 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block); 519 520 // accessors for final result 521 BlockList* linear_scan_order() const { return _linear_scan_order; } 522 int num_loops() const { return _num_loops; } 523 }; 524 525 526 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) : 527 _max_block_id(BlockBegin::number_of_blocks()), 528 _num_blocks(0), 529 _num_loops(0), 530 _iterative_dominators(false), 531 _visited_blocks(_max_block_id), 532 _active_blocks(_max_block_id), 533 _dominator_blocks(_max_block_id), 534 _forward_branches(_max_block_id, 0), 535 _loop_end_blocks(8), 536 _work_list(8), 537 _linear_scan_order(NULL), // initialized later with correct size 538 _loop_map(0, 0), // initialized later with correct size 539 _compilation(c) 540 { 541 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order")); 542 543 init_visited(); 544 count_edges(start_block, NULL); 545 546 if (compilation()->is_profiling()) { 547 ciMethod *method = compilation()->method(); 548 if (!method->is_accessor()) { 549 ciMethodData* md = method->method_data_or_null(); 550 assert(md != NULL, "Sanity"); 551 md->set_compilation_stats(_num_loops, _num_blocks); 552 } 553 } 554 555 if (_num_loops > 0) { 556 mark_loops(); 557 clear_non_natural_loops(start_block); 558 assign_loop_depth(start_block); 559 } 560 561 compute_order(start_block); 562 compute_dominators(); 563 564 NOT_PRODUCT(print_blocks()); 565 DEBUG_ONLY(verify()); 566 } 567 568 569 // Traverse the CFG: 570 // * count total number of blocks 571 // * count all incoming edges and backward incoming edges 572 // * number loop header blocks 573 // * create a list with all loop end blocks 574 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) { 575 TRACE_LINEAR_SCAN(3, tty->print_cr("Enter count_edges for block B%d coming from B%d", cur->block_id(), parent != NULL ? parent->block_id() : -1)); 576 assert(cur->dominator() == NULL, "dominator already initialized"); 577 578 if (is_active(cur)) { 579 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch")); 580 assert(is_visited(cur), "block must be visisted when block is active"); 581 assert(parent != NULL, "must have parent"); 582 583 cur->set(BlockBegin::backward_branch_target_flag); 584 585 // When a loop header is also the start of an exception handler, then the backward branch is 586 // an exception edge. Because such edges are usually critical edges which cannot be split, the 587 // loop must be excluded here from processing. 588 if (cur->is_set(BlockBegin::exception_entry_flag)) { 589 // Make sure that dominators are correct in this weird situation 590 _iterative_dominators = true; 591 return; 592 } 593 594 cur->set(BlockBegin::linear_scan_loop_header_flag); 595 parent->set(BlockBegin::linear_scan_loop_end_flag); 596 597 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur, 598 "loop end blocks must have one successor (critical edges are split)"); 599 600 _loop_end_blocks.append(parent); 601 return; 602 } 603 604 // increment number of incoming forward branches 605 inc_forward_branches(cur); 606 607 if (is_visited(cur)) { 608 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited")); 609 return; 610 } 611 612 _num_blocks++; 613 set_visited(cur); 614 set_active(cur); 615 616 // recursive call for all successors 617 int i; 618 for (i = cur->number_of_sux() - 1; i >= 0; i--) { 619 count_edges(cur->sux_at(i), cur); 620 } 621 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) { 622 count_edges(cur->exception_handler_at(i), cur); 623 } 624 625 clear_active(cur); 626 627 // Each loop has a unique number. 628 // When multiple loops are nested, assign_loop_depth assumes that the 629 // innermost loop has the lowest number. This is guaranteed by setting 630 // the loop number after the recursive calls for the successors above 631 // have returned. 632 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) { 633 assert(cur->loop_index() == -1, "cannot set loop-index twice"); 634 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops)); 635 636 cur->set_loop_index(_num_loops); 637 _loop_headers.append(cur); 638 _num_loops++; 639 } 640 641 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id())); 642 } 643 644 645 void ComputeLinearScanOrder::mark_loops() { 646 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops")); 647 648 _loop_map = BitMap2D(_num_loops, _max_block_id); 649 _loop_map.clear(); 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 mulitple 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 != NULL && b != NULL, "must have input blocks"); 760 761 _dominator_blocks.clear(); 762 while (a != NULL) { 763 _dominator_blocks.set_bit(a->block_id()); 764 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized"); 765 a = a->dominator(); 766 } 767 while (b != NULL && !_dominator_blocks.at(b->block_id())) { 768 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized"); 769 b = b->dominator(); 770 } 771 772 assert(b != NULL, "could not find dominator"); 773 return b; 774 } 775 776 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) { 777 if (cur->dominator() == NULL) { 778 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id())); 779 cur->set_dominator(parent); 780 781 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) { 782 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())); 783 // Does not hold for exception blocks 784 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), ""); 785 cur->set_dominator(common_dominator(cur->dominator(), parent)); 786 } 787 788 // Additional edge to xhandler of all our successors 789 // range check elimination needs that the state at the end of a 790 // block be valid in every block it dominates so cur must dominate 791 // the exception handlers of its successors. 792 int num_cur_xhandler = cur->number_of_exception_handlers(); 793 for (int j = 0; j < num_cur_xhandler; j++) { 794 BlockBegin* xhandler = cur->exception_handler_at(j); 795 compute_dominator(xhandler, parent); 796 } 797 } 798 799 800 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) { 801 BlockBegin* single_sux = NULL; 802 if (cur->number_of_sux() == 1) { 803 single_sux = cur->sux_at(0); 804 } 805 806 // limit loop-depth to 15 bit (only for security reason, it will never be so big) 807 int weight = (cur->loop_depth() & 0x7FFF) << 16; 808 809 // general macro for short definition of weight flags 810 // the first instance of INC_WEIGHT_IF has the highest priority 811 int cur_bit = 15; 812 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--; 813 814 // this is necessery for the (very rare) case that two successing blocks have 815 // the same loop depth, but a different loop index (can happen for endless loops 816 // with exception handlers) 817 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag)); 818 819 // loop end blocks (blocks that end with a backward branch) are added 820 // after all other blocks of the loop. 821 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag)); 822 823 // critical edge split blocks are prefered because than they have a bigger 824 // proability to be completely empty 825 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag)); 826 827 // exceptions should not be thrown in normal control flow, so these blocks 828 // are added as late as possible 829 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL)); 830 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL)); 831 832 // exceptions handlers are added as late as possible 833 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag)); 834 835 // guarantee that weight is > 0 836 weight |= 1; 837 838 #undef INC_WEIGHT_IF 839 assert(cur_bit >= 0, "too many flags"); 840 assert(weight > 0, "weight cannot become negative"); 841 842 return weight; 843 } 844 845 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) { 846 // Discount the edge just traveled. 847 // When the number drops to zero, all forward branches were processed 848 if (dec_forward_branches(cur) != 0) { 849 return false; 850 } 851 852 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)"); 853 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)"); 854 return true; 855 } 856 857 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) { 858 assert(_work_list.index_of(cur) == -1, "block already in work list"); 859 860 int cur_weight = compute_weight(cur); 861 862 // the linear_scan_number is used to cache the weight of a block 863 cur->set_linear_scan_number(cur_weight); 864 865 #ifndef PRODUCT 866 if (StressLinearScan) { 867 _work_list.insert_before(0, cur); 868 return; 869 } 870 #endif 871 872 _work_list.append(NULL); // provide space for new element 873 874 int insert_idx = _work_list.length() - 1; 875 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) { 876 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1)); 877 insert_idx--; 878 } 879 _work_list.at_put(insert_idx, cur); 880 881 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id())); 882 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())); 883 884 #ifdef ASSERT 885 for (int i = 0; i < _work_list.length(); i++) { 886 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set"); 887 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist"); 888 } 889 #endif 890 } 891 892 void ComputeLinearScanOrder::append_block(BlockBegin* cur) { 893 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())); 894 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice"); 895 896 // currently, the linear scan order and code emit order are equal. 897 // therefore the linear_scan_number and the weight of a block must also 898 // be equal. 899 cur->set_linear_scan_number(_linear_scan_order->length()); 900 _linear_scan_order->append(cur); 901 } 902 903 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) { 904 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order")); 905 906 // the start block is always the first block in the linear scan order 907 _linear_scan_order = new BlockList(_num_blocks); 908 append_block(start_block); 909 910 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction"); 911 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry(); 912 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry(); 913 914 BlockBegin* sux_of_osr_entry = NULL; 915 if (osr_entry != NULL) { 916 // special handling for osr entry: 917 // ignore the edge between the osr entry and its successor for processing 918 // the osr entry block is added manually below 919 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor"); 920 assert(osr_entry->sux_at(0)->number_of_preds() >= 2, "sucessor of osr entry must have two predecessors (otherwise it is not present in normal control flow"); 921 922 sux_of_osr_entry = osr_entry->sux_at(0); 923 dec_forward_branches(sux_of_osr_entry); 924 925 compute_dominator(osr_entry, start_block); 926 _iterative_dominators = true; 927 } 928 compute_dominator(std_entry, start_block); 929 930 // start processing with standard entry block 931 assert(_work_list.is_empty(), "list must be empty before processing"); 932 933 if (ready_for_processing(std_entry)) { 934 sort_into_work_list(std_entry); 935 } else { 936 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)"); 937 } 938 939 do { 940 BlockBegin* cur = _work_list.pop(); 941 942 if (cur == sux_of_osr_entry) { 943 // the osr entry block is ignored in normal processing, it is never added to the 944 // work list. Instead, it is added as late as possible manually here. 945 append_block(osr_entry); 946 compute_dominator(cur, osr_entry); 947 } 948 append_block(cur); 949 950 int i; 951 int num_sux = cur->number_of_sux(); 952 // changed loop order to get "intuitive" order of if- and else-blocks 953 for (i = 0; i < num_sux; i++) { 954 BlockBegin* sux = cur->sux_at(i); 955 compute_dominator(sux, cur); 956 if (ready_for_processing(sux)) { 957 sort_into_work_list(sux); 958 } 959 } 960 num_sux = cur->number_of_exception_handlers(); 961 for (i = 0; i < num_sux; i++) { 962 BlockBegin* sux = cur->exception_handler_at(i); 963 if (ready_for_processing(sux)) { 964 sort_into_work_list(sux); 965 } 966 } 967 } while (_work_list.length() > 0); 968 } 969 970 971 bool ComputeLinearScanOrder::compute_dominators_iter() { 972 bool changed = false; 973 int num_blocks = _linear_scan_order->length(); 974 975 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator"); 976 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors"); 977 for (int i = 1; i < num_blocks; i++) { 978 BlockBegin* block = _linear_scan_order->at(i); 979 980 BlockBegin* dominator = block->pred_at(0); 981 int num_preds = block->number_of_preds(); 982 983 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id())); 984 985 for (int j = 0; j < num_preds; j++) { 986 987 BlockBegin *pred = block->pred_at(j); 988 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id())); 989 990 if (block->is_set(BlockBegin::exception_entry_flag)) { 991 dominator = common_dominator(dominator, pred); 992 int num_pred_preds = pred->number_of_preds(); 993 for (int k = 0; k < num_pred_preds; k++) { 994 dominator = common_dominator(dominator, pred->pred_at(k)); 995 } 996 } else { 997 dominator = common_dominator(dominator, pred); 998 } 999 } 1000 1001 if (dominator != block->dominator()) { 1002 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())); 1003 1004 block->set_dominator(dominator); 1005 changed = true; 1006 } 1007 } 1008 return changed; 1009 } 1010 1011 void ComputeLinearScanOrder::compute_dominators() { 1012 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators)); 1013 1014 // iterative computation of dominators is only required for methods with non-natural loops 1015 // and OSR-methods. For all other methods, the dominators computed when generating the 1016 // linear scan block order are correct. 1017 if (_iterative_dominators) { 1018 do { 1019 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation")); 1020 } while (compute_dominators_iter()); 1021 } 1022 1023 // check that dominators are correct 1024 assert(!compute_dominators_iter(), "fix point not reached"); 1025 1026 // Add Blocks to dominates-Array 1027 int num_blocks = _linear_scan_order->length(); 1028 for (int i = 0; i < num_blocks; i++) { 1029 BlockBegin* block = _linear_scan_order->at(i); 1030 1031 BlockBegin *dom = block->dominator(); 1032 if (dom) { 1033 assert(dom->dominator_depth() != -1, "Dominator must have been visited before"); 1034 dom->dominates()->append(block); 1035 block->set_dominator_depth(dom->dominator_depth() + 1); 1036 } else { 1037 block->set_dominator_depth(0); 1038 } 1039 } 1040 } 1041 1042 1043 #ifndef PRODUCT 1044 void ComputeLinearScanOrder::print_blocks() { 1045 if (TraceLinearScanLevel >= 2) { 1046 tty->print_cr("----- loop information:"); 1047 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) { 1048 BlockBegin* cur = _linear_scan_order->at(block_idx); 1049 1050 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id()); 1051 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) { 1052 tty->print ("%d ", is_block_in_loop(loop_idx, cur)); 1053 } 1054 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth()); 1055 } 1056 } 1057 1058 if (TraceLinearScanLevel >= 1) { 1059 tty->print_cr("----- linear-scan block order:"); 1060 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) { 1061 BlockBegin* cur = _linear_scan_order->at(block_idx); 1062 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth()); 1063 1064 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " "); 1065 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " "); 1066 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " "); 1067 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " "); 1068 1069 if (cur->dominator() != NULL) { 1070 tty->print(" dom: B%d ", cur->dominator()->block_id()); 1071 } else { 1072 tty->print(" dom: NULL "); 1073 } 1074 1075 if (cur->number_of_preds() > 0) { 1076 tty->print(" preds: "); 1077 for (int j = 0; j < cur->number_of_preds(); j++) { 1078 BlockBegin* pred = cur->pred_at(j); 1079 tty->print("B%d ", pred->block_id()); 1080 } 1081 } 1082 if (cur->number_of_sux() > 0) { 1083 tty->print(" sux: "); 1084 for (int j = 0; j < cur->number_of_sux(); j++) { 1085 BlockBegin* sux = cur->sux_at(j); 1086 tty->print("B%d ", sux->block_id()); 1087 } 1088 } 1089 if (cur->number_of_exception_handlers() > 0) { 1090 tty->print(" ex: "); 1091 for (int j = 0; j < cur->number_of_exception_handlers(); j++) { 1092 BlockBegin* ex = cur->exception_handler_at(j); 1093 tty->print("B%d ", ex->block_id()); 1094 } 1095 } 1096 tty->cr(); 1097 } 1098 } 1099 } 1100 #endif 1101 1102 #ifdef ASSERT 1103 void ComputeLinearScanOrder::verify() { 1104 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list"); 1105 1106 if (StressLinearScan) { 1107 // blocks are scrambled when StressLinearScan is used 1108 return; 1109 } 1110 1111 // check that all successors of a block have a higher linear-scan-number 1112 // and that all predecessors of a block have a lower linear-scan-number 1113 // (only backward branches of loops are ignored) 1114 int i; 1115 for (i = 0; i < _linear_scan_order->length(); i++) { 1116 BlockBegin* cur = _linear_scan_order->at(i); 1117 1118 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number"); 1119 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number"); 1120 1121 int j; 1122 for (j = cur->number_of_sux() - 1; j >= 0; j--) { 1123 BlockBegin* sux = cur->sux_at(j); 1124 1125 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number"); 1126 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) { 1127 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order"); 1128 } 1129 if (cur->loop_depth() == sux->loop_depth()) { 1130 assert(cur->loop_index() == sux->loop_index() || sux->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index"); 1131 } 1132 } 1133 1134 for (j = cur->number_of_preds() - 1; j >= 0; j--) { 1135 BlockBegin* pred = cur->pred_at(j); 1136 1137 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number"); 1138 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) { 1139 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order"); 1140 } 1141 if (cur->loop_depth() == pred->loop_depth()) { 1142 assert(cur->loop_index() == pred->loop_index() || cur->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index"); 1143 } 1144 1145 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors"); 1146 } 1147 1148 // check dominator 1149 if (i == 0) { 1150 assert(cur->dominator() == NULL, "first block has no dominator"); 1151 } else { 1152 assert(cur->dominator() != NULL, "all but first block must have dominator"); 1153 } 1154 // Assertion does not hold for exception handlers 1155 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"); 1156 } 1157 1158 // check that all loops are continuous 1159 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) { 1160 int block_idx = 0; 1161 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop"); 1162 1163 // skip blocks before the loop 1164 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) { 1165 block_idx++; 1166 } 1167 // skip blocks of loop 1168 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) { 1169 block_idx++; 1170 } 1171 // after the first non-loop block, there must not be another loop-block 1172 while (block_idx < _num_blocks) { 1173 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order"); 1174 block_idx++; 1175 } 1176 } 1177 } 1178 #endif 1179 1180 1181 void IR::compute_code() { 1182 assert(is_valid(), "IR must be valid"); 1183 1184 ComputeLinearScanOrder compute_order(compilation(), start()); 1185 _num_loops = compute_order.num_loops(); 1186 _code = compute_order.linear_scan_order(); 1187 } 1188 1189 1190 void IR::compute_use_counts() { 1191 // make sure all values coming out of this block get evaluated. 1192 int num_blocks = _code->length(); 1193 for (int i = 0; i < num_blocks; i++) { 1194 _code->at(i)->end()->state()->pin_stack_for_linear_scan(); 1195 } 1196 1197 // compute use counts 1198 UseCountComputer::compute(_code); 1199 } 1200 1201 1202 void IR::iterate_preorder(BlockClosure* closure) { 1203 assert(is_valid(), "IR must be valid"); 1204 start()->iterate_preorder(closure); 1205 } 1206 1207 1208 void IR::iterate_postorder(BlockClosure* closure) { 1209 assert(is_valid(), "IR must be valid"); 1210 start()->iterate_postorder(closure); 1211 } 1212 1213 void IR::iterate_linear_scan_order(BlockClosure* closure) { 1214 linear_scan_order()->iterate_forward(closure); 1215 } 1216 1217 1218 #ifndef PRODUCT 1219 class BlockPrinter: public BlockClosure { 1220 private: 1221 InstructionPrinter* _ip; 1222 bool _cfg_only; 1223 bool _live_only; 1224 1225 public: 1226 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) { 1227 _ip = ip; 1228 _cfg_only = cfg_only; 1229 _live_only = live_only; 1230 } 1231 1232 virtual void block_do(BlockBegin* block) { 1233 if (_cfg_only) { 1234 _ip->print_instr(block); tty->cr(); 1235 } else { 1236 block->print_block(*_ip, _live_only); 1237 } 1238 } 1239 }; 1240 1241 1242 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) { 1243 ttyLocker ttyl; 1244 InstructionPrinter ip(!cfg_only); 1245 BlockPrinter bp(&ip, cfg_only, live_only); 1246 start->iterate_preorder(&bp); 1247 tty->cr(); 1248 } 1249 1250 void IR::print(bool cfg_only, bool live_only) { 1251 if (is_valid()) { 1252 print(start(), cfg_only, live_only); 1253 } else { 1254 tty->print_cr("invalid IR"); 1255 } 1256 } 1257 1258 1259 define_array(BlockListArray, BlockList*) 1260 define_stack(BlockListList, BlockListArray) 1261 1262 class PredecessorValidator : public BlockClosure { 1263 private: 1264 BlockListList* _predecessors; 1265 BlockList* _blocks; 1266 1267 static int cmp(BlockBegin** a, BlockBegin** b) { 1268 return (*a)->block_id() - (*b)->block_id(); 1269 } 1270 1271 public: 1272 PredecessorValidator(IR* hir) { 1273 ResourceMark rm; 1274 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL); 1275 _blocks = new BlockList(); 1276 1277 int i; 1278 hir->start()->iterate_preorder(this); 1279 if (hir->code() != NULL) { 1280 assert(hir->code()->length() == _blocks->length(), "must match"); 1281 for (i = 0; i < _blocks->length(); i++) { 1282 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists"); 1283 } 1284 } 1285 1286 for (i = 0; i < _blocks->length(); i++) { 1287 BlockBegin* block = _blocks->at(i); 1288 BlockList* preds = _predecessors->at(block->block_id()); 1289 if (preds == NULL) { 1290 assert(block->number_of_preds() == 0, "should be the same"); 1291 continue; 1292 } 1293 1294 // clone the pred list so we can mutate it 1295 BlockList* pred_copy = new BlockList(); 1296 int j; 1297 for (j = 0; j < block->number_of_preds(); j++) { 1298 pred_copy->append(block->pred_at(j)); 1299 } 1300 // sort them in the same order 1301 preds->sort(cmp); 1302 pred_copy->sort(cmp); 1303 int length = MIN2(preds->length(), block->number_of_preds()); 1304 for (j = 0; j < block->number_of_preds(); j++) { 1305 assert(preds->at(j) == pred_copy->at(j), "must match"); 1306 } 1307 1308 assert(preds->length() == block->number_of_preds(), "should be the same"); 1309 } 1310 } 1311 1312 virtual void block_do(BlockBegin* block) { 1313 _blocks->append(block); 1314 BlockEnd* be = block->end(); 1315 int n = be->number_of_sux(); 1316 int i; 1317 for (i = 0; i < n; i++) { 1318 BlockBegin* sux = be->sux_at(i); 1319 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler"); 1320 1321 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL); 1322 if (preds == NULL) { 1323 preds = new BlockList(); 1324 _predecessors->at_put(sux->block_id(), preds); 1325 } 1326 preds->append(block); 1327 } 1328 1329 n = block->number_of_exception_handlers(); 1330 for (i = 0; i < n; i++) { 1331 BlockBegin* sux = block->exception_handler_at(i); 1332 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler"); 1333 1334 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL); 1335 if (preds == NULL) { 1336 preds = new BlockList(); 1337 _predecessors->at_put(sux->block_id(), preds); 1338 } 1339 preds->append(block); 1340 } 1341 } 1342 }; 1343 1344 class VerifyBlockBeginField : public BlockClosure { 1345 1346 public: 1347 1348 virtual void block_do(BlockBegin *block) { 1349 for ( Instruction *cur = block; cur != NULL; cur = cur->next()) { 1350 assert(cur->block() == block, "Block begin is not correct"); 1351 } 1352 } 1353 }; 1354 1355 void IR::verify() { 1356 #ifdef ASSERT 1357 PredecessorValidator pv(this); 1358 VerifyBlockBeginField verifier; 1359 this->iterate_postorder(&verifier); 1360 #endif 1361 } 1362 1363 #endif // PRODUCT 1364 1365 void SubstitutionResolver::visit(Value* v) { 1366 Value v0 = *v; 1367 if (v0) { 1368 Value vs = v0->subst(); 1369 if (vs != v0) { 1370 *v = v0->subst(); 1371 } 1372 } 1373 } 1374 1375 #ifdef ASSERT 1376 class SubstitutionChecker: public ValueVisitor { 1377 void visit(Value* v) { 1378 Value v0 = *v; 1379 if (v0) { 1380 Value vs = v0->subst(); 1381 assert(vs == v0, "missed substitution"); 1382 } 1383 } 1384 }; 1385 #endif 1386 1387 1388 void SubstitutionResolver::block_do(BlockBegin* block) { 1389 Instruction* last = NULL; 1390 for (Instruction* n = block; n != NULL;) { 1391 n->values_do(this); 1392 // need to remove this instruction from the instruction stream 1393 if (n->subst() != n) { 1394 assert(last != NULL, "must have last"); 1395 last->set_next(n->next()); 1396 } else { 1397 last = n; 1398 } 1399 n = last->next(); 1400 } 1401 1402 #ifdef ASSERT 1403 SubstitutionChecker check_substitute; 1404 if (block->state()) block->state()->values_do(&check_substitute); 1405 block->block_values_do(&check_substitute); 1406 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute); 1407 #endif 1408 }