rev 4136 : 7153771: array bound check elimination for c1
Summary: when possible optimize out array bound checks, inserting predicates when needed.
Reviewed-by:

   1 /*
   2  * Copyright (c) 1999, 2012, 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 "utilities/bitMap.inline.hpp"
  33 
  34 
  35 // Implementation of XHandlers
  36 //
  37 // Note: This code could eventually go away if we are
  38 //       just using the ciExceptionHandlerStream.
  39 
  40 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) {
  41   ciExceptionHandlerStream s(method);
  42   while (!s.is_done()) {
  43     _list.append(new XHandler(s.handler()));
  44     s.next();
  45   }
  46   assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent");
  47 }
  48 
  49 // deep copy of all XHandler contained in list
  50 XHandlers::XHandlers(XHandlers* other) :
  51   _list(other->length())
  52 {
  53   for (int i = 0; i < other->length(); i++) {
  54     _list.append(new XHandler(other->handler_at(i)));
  55   }
  56 }
  57 
  58 // Returns whether a particular exception type can be caught.  Also
  59 // returns true if klass is unloaded or any exception handler
  60 // classes are unloaded.  type_is_exact indicates whether the throw
  61 // is known to be exactly that class or it might throw a subtype.
  62 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const {
  63   // the type is unknown so be conservative
  64   if (!klass->is_loaded()) {
  65     return true;
  66   }
  67 
  68   for (int i = 0; i < length(); i++) {
  69     XHandler* handler = handler_at(i);
  70     if (handler->is_catch_all()) {
  71       // catch of ANY
  72       return true;
  73     }
  74     ciInstanceKlass* handler_klass = handler->catch_klass();
  75     // if it's unknown it might be catchable
  76     if (!handler_klass->is_loaded()) {
  77       return true;
  78     }
  79     // if the throw type is definitely a subtype of the catch type
  80     // then it can be caught.
  81     if (klass->is_subtype_of(handler_klass)) {
  82       return true;
  83     }
  84     if (!type_is_exact) {
  85       // If the type isn't exactly known then it can also be caught by
  86       // catch statements where the inexact type is a subtype of the
  87       // catch type.
  88       // given: foo extends bar extends Exception
  89       // throw bar can be caught by catch foo, catch bar, and catch
  90       // Exception, however it can't be caught by any handlers without
  91       // bar in its type hierarchy.
  92       if (handler_klass->is_subtype_of(klass)) {
  93         return true;
  94       }
  95     }
  96   }
  97 
  98   return false;
  99 }
 100 
 101 
 102 bool XHandlers::equals(XHandlers* others) const {
 103   if (others == NULL) return false;
 104   if (length() != others->length()) return false;
 105 
 106   for (int i = 0; i < length(); i++) {
 107     if (!handler_at(i)->equals(others->handler_at(i))) return false;
 108   }
 109   return true;
 110 }
 111 
 112 bool XHandler::equals(XHandler* other) const {
 113   assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
 114 
 115   if (entry_pco() != other->entry_pco()) return false;
 116   if (scope_count() != other->scope_count()) return false;
 117   if (_desc != other->_desc) return false;
 118 
 119   assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
 120   return true;
 121 }
 122 
 123 
 124 // Implementation of IRScope
 125 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) {
 126   GraphBuilder gm(compilation, this);
 127   NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats());
 128   if (compilation->bailed_out()) return NULL;
 129   return gm.start();
 130 }
 131 
 132 
 133 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph)
 134 : _callees(2)
 135 , _compilation(compilation)
 136 , _requires_phi_function(method->max_locals())
 137 {
 138   _caller             = caller;
 139   _level              = caller == NULL ?  0 : caller->level() + 1;
 140   _method             = method;
 141   _xhandlers          = new XHandlers(method);
 142   _number_of_locks    = 0;
 143   _monitor_pairing_ok = method->has_balanced_monitors();
 144   _wrote_final        = false;
 145   _start              = NULL;
 146 
 147   if (osr_bci == -1) {
 148     _requires_phi_function.clear();
 149   } else {
 150         // selective creation of phi functions is not possibel in osr-methods
 151     _requires_phi_function.set_range(0, method->max_locals());
 152   }
 153 
 154   assert(method->holder()->is_loaded() , "method holder must be loaded");
 155 
 156   // build graph if monitor pairing is ok
 157   if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
 158 }
 159 
 160 
 161 int IRScope::max_stack() const {
 162   int my_max = method()->max_stack();
 163   int callee_max = 0;
 164   for (int i = 0; i < number_of_callees(); i++) {
 165     callee_max = MAX2(callee_max, callee_no(i)->max_stack());
 166   }
 167   return my_max + callee_max;
 168 }
 169 
 170 
 171 bool IRScopeDebugInfo::should_reexecute() {
 172   ciMethod* cur_method = scope()->method();
 173   int       cur_bci    = bci();
 174   if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
 175     Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
 176     return Interpreter::bytecode_should_reexecute(code);
 177   } else
 178     return false;
 179 }
 180 
 181 
 182 // Implementation of CodeEmitInfo
 183 
 184 // Stack must be NON-null
 185 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers)
 186   : _scope(stack->scope())
 187   , _scope_debug_info(NULL)
 188   , _oop_map(NULL)
 189   , _stack(stack)
 190   , _exception_handlers(exception_handlers)
 191   , _is_method_handle_invoke(false) {

 192   assert(_stack != NULL, "must be non null");
 193 }
 194 
 195 
 196 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
 197   : _scope(info->_scope)
 198   , _exception_handlers(NULL)
 199   , _scope_debug_info(NULL)
 200   , _oop_map(NULL)
 201   , _stack(stack == NULL ? info->_stack : stack)
 202   , _is_method_handle_invoke(info->_is_method_handle_invoke) {

 203 
 204   // deep copy of exception handlers
 205   if (info->_exception_handlers != NULL) {
 206     _exception_handlers = new XHandlers(info->_exception_handlers);
 207   }
 208 }
 209 
 210 
 211 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
 212   // record the safepoint before recording the debug info for enclosing scopes
 213   recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
 214   _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
 215   recorder->end_safepoint(pc_offset);
 216 }
 217 
 218 
 219 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
 220   assert(_oop_map != NULL, "oop map must already exist");
 221   assert(opr->is_single_cpu(), "should not call otherwise");
 222 
 223   VMReg name = frame_map()->regname(opr);
 224   _oop_map->set_oop(name);
 225 }
 226 
 227 
 228 
 229 
 230 // Implementation of IR
 231 
 232 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
 233     _locals_size(in_WordSize(-1))
 234   , _num_loops(0) {
 235   // setup IR fields
 236   _compilation = compilation;
 237   _top_scope   = new IRScope(compilation, NULL, -1, method, osr_bci, true);
 238   _code        = NULL;
 239 }
 240 
 241 
 242 void IR::optimize() {
 243   Optimizer opt(this);
 244   if (!compilation()->profile_branches()) {
 245     if (DoCEE) {
 246       opt.eliminate_conditional_expressions();
 247 #ifndef PRODUCT
 248       if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
 249       if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
 250 #endif
 251     }
 252     if (EliminateBlocks) {
 253       opt.eliminate_blocks();
 254 #ifndef PRODUCT
 255       if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
 256       if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
 257 #endif
 258     }
 259   }




 260   if (EliminateNullChecks) {
 261     opt.eliminate_null_checks();
 262 #ifndef PRODUCT
 263     if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
 264     if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
 265 #endif
 266   }
 267 }
 268 
 269 
 270 static int sort_pairs(BlockPair** a, BlockPair** b) {
 271   if ((*a)->from() == (*b)->from()) {
 272     return (*a)->to()->block_id() - (*b)->to()->block_id();
 273   } else {
 274     return (*a)->from()->block_id() - (*b)->from()->block_id();
 275   }
 276 }
 277 
 278 
 279 class CriticalEdgeFinder: public BlockClosure {
 280   BlockPairList blocks;
 281   IR*       _ir;
 282 
 283  public:
 284   CriticalEdgeFinder(IR* ir): _ir(ir) {}
 285   void block_do(BlockBegin* bb) {
 286     BlockEnd* be = bb->end();
 287     int nos = be->number_of_sux();
 288     if (nos >= 2) {
 289       for (int i = 0; i < nos; i++) {
 290         BlockBegin* sux = be->sux_at(i);
 291         if (sux->number_of_preds() >= 2) {
 292           blocks.append(new BlockPair(bb, sux));
 293         }
 294       }
 295     }
 296   }
 297 
 298   void split_edges() {
 299     BlockPair* last_pair = NULL;
 300     blocks.sort(sort_pairs);
 301     for (int i = 0; i < blocks.length(); i++) {
 302       BlockPair* pair = blocks.at(i);
 303       if (last_pair != NULL && pair->is_same(last_pair)) continue;
 304       BlockBegin* from = pair->from();
 305       BlockBegin* to = pair->to();
 306       BlockBegin* split = from->insert_block_between(to);
 307 #ifndef PRODUCT
 308       if ((PrintIR || PrintIR1) && Verbose) {
 309         tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
 310                       from->block_id(), to->block_id(), split->block_id());
 311       }
 312 #endif
 313       last_pair = pair;
 314     }
 315   }
 316 };
 317 
 318 void IR::split_critical_edges() {
 319   CriticalEdgeFinder cef(this);
 320 
 321   iterate_preorder(&cef);
 322   cef.split_edges();
 323 }
 324 
 325 
 326 class UseCountComputer: public ValueVisitor, BlockClosure {
 327  private:
 328   void visit(Value* n) {
 329     // Local instructions and Phis for expression stack values at the
 330     // start of basic blocks are not added to the instruction list
 331     if (!(*n)->is_linked() && (*n)->can_be_linked()) {
 332       assert(false, "a node was not appended to the graph");
 333       Compilation::current()->bailout("a node was not appended to the graph");
 334     }
 335     // use n's input if not visited before
 336     if (!(*n)->is_pinned() && !(*n)->has_uses()) {
 337       // note: a) if the instruction is pinned, it will be handled by compute_use_count
 338       //       b) if the instruction has uses, it was touched before
 339       //       => in both cases we don't need to update n's values
 340       uses_do(n);
 341     }
 342     // use n
 343     (*n)->_use_count++;
 344   }
 345 
 346   Values* worklist;
 347   int depth;
 348   enum {
 349     max_recurse_depth = 20
 350   };
 351 
 352   void uses_do(Value* n) {
 353     depth++;
 354     if (depth > max_recurse_depth) {
 355       // don't allow the traversal to recurse too deeply
 356       worklist->push(*n);
 357     } else {
 358       (*n)->input_values_do(this);
 359       // special handling for some instructions
 360       if ((*n)->as_BlockEnd() != NULL) {
 361         // note on BlockEnd:
 362         //   must 'use' the stack only if the method doesn't
 363         //   terminate, however, in those cases stack is empty
 364         (*n)->state_values_do(this);
 365       }
 366     }
 367     depth--;
 368   }
 369 
 370   void block_do(BlockBegin* b) {
 371     depth = 0;
 372     // process all pinned nodes as the roots of expression trees
 373     for (Instruction* n = b; n != NULL; n = n->next()) {
 374       if (n->is_pinned()) uses_do(&n);
 375     }
 376     assert(depth == 0, "should have counted back down");
 377 
 378     // now process any unpinned nodes which recursed too deeply
 379     while (worklist->length() > 0) {
 380       Value t = worklist->pop();
 381       if (!t->is_pinned()) {
 382         // compute the use count
 383         uses_do(&t);
 384 
 385         // pin the instruction so that LIRGenerator doesn't recurse
 386         // too deeply during it's evaluation.
 387         t->pin();
 388       }
 389     }
 390     assert(depth == 0, "should have counted back down");
 391   }
 392 
 393   UseCountComputer() {
 394     worklist = new Values();
 395     depth = 0;
 396   }
 397 
 398  public:
 399   static void compute(BlockList* blocks) {
 400     UseCountComputer ucc;
 401     blocks->iterate_backward(&ucc);
 402   }
 403 };
 404 
 405 
 406 // helper macro for short definition of trace-output inside code
 407 #ifndef PRODUCT
 408   #define TRACE_LINEAR_SCAN(level, code)       \
 409     if (TraceLinearScanLevel >= level) {       \
 410       code;                                    \
 411     }
 412 #else
 413   #define TRACE_LINEAR_SCAN(level, code)
 414 #endif
 415 
 416 class ComputeLinearScanOrder : public StackObj {
 417  private:
 418   int        _max_block_id;        // the highest block_id of a block
 419   int        _num_blocks;          // total number of blocks (smaller than _max_block_id)
 420   int        _num_loops;           // total number of loops
 421   bool       _iterative_dominators;// method requires iterative computation of dominatiors
 422 
 423   BlockList* _linear_scan_order;   // the resulting list of blocks in correct order
 424 
 425   BitMap     _visited_blocks;      // used for recursive processing of blocks
 426   BitMap     _active_blocks;       // used for recursive processing of blocks
 427   BitMap     _dominator_blocks;    // temproary BitMap used for computation of dominator
 428   intArray   _forward_branches;    // number of incoming forward branches for each block
 429   BlockList  _loop_end_blocks;     // list of all loop end blocks collected during count_edges
 430   BitMap2D   _loop_map;            // two-dimensional bit set: a bit is set if a block is contained in a loop
 431   BlockList  _work_list;           // temporary list (used in mark_loops and compute_order)

 432 
 433   Compilation* _compilation;
 434 
 435   // accessors for _visited_blocks and _active_blocks
 436   void init_visited()                     { _active_blocks.clear(); _visited_blocks.clear(); }
 437   bool is_visited(BlockBegin* b) const    { return _visited_blocks.at(b->block_id()); }
 438   bool is_active(BlockBegin* b) const     { return _active_blocks.at(b->block_id()); }
 439   void set_visited(BlockBegin* b)         { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
 440   void set_active(BlockBegin* b)          { assert(!is_active(b), "already set");  _active_blocks.set_bit(b->block_id()); }
 441   void clear_active(BlockBegin* b)        { assert(is_active(b), "not already");   _active_blocks.clear_bit(b->block_id()); }
 442 
 443   // accessors for _forward_branches
 444   void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
 445   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()); }
 446 
 447   // accessors for _loop_map
 448   bool is_block_in_loop   (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
 449   void set_block_in_loop  (int loop_idx, BlockBegin* b)       { _loop_map.set_bit(loop_idx, b->block_id()); }
 450   void clear_block_in_loop(int loop_idx, int block_id)        { _loop_map.clear_bit(loop_idx, block_id); }
 451 
 452   // count edges between blocks
 453   void count_edges(BlockBegin* cur, BlockBegin* parent);
 454 
 455   // loop detection
 456   void mark_loops();
 457   void clear_non_natural_loops(BlockBegin* start_block);
 458   void assign_loop_depth(BlockBegin* start_block);
 459 
 460   // computation of final block order
 461   BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
 462   void compute_dominator(BlockBegin* cur, BlockBegin* parent);
 463   int  compute_weight(BlockBegin* cur);
 464   bool ready_for_processing(BlockBegin* cur);
 465   void sort_into_work_list(BlockBegin* b);
 466   void append_block(BlockBegin* cur);
 467   void compute_order(BlockBegin* start_block);
 468 
 469   // fixup of dominators for non-natural loops
 470   bool compute_dominators_iter();
 471   void compute_dominators();
 472 
 473   // debug functions
 474   NOT_PRODUCT(void print_blocks();)
 475   DEBUG_ONLY(void verify();)
 476 
 477   Compilation* compilation() const { return _compilation; }
 478  public:
 479   ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
 480 
 481   // accessors for final result
 482   BlockList* linear_scan_order() const    { return _linear_scan_order; }
 483   int        num_loops() const            { return _num_loops; }
 484 };
 485 
 486 
 487 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
 488   _max_block_id(BlockBegin::number_of_blocks()),
 489   _num_blocks(0),
 490   _num_loops(0),
 491   _iterative_dominators(false),
 492   _visited_blocks(_max_block_id),
 493   _active_blocks(_max_block_id),
 494   _dominator_blocks(_max_block_id),
 495   _forward_branches(_max_block_id, 0),
 496   _loop_end_blocks(8),
 497   _work_list(8),
 498   _linear_scan_order(NULL), // initialized later with correct size
 499   _loop_map(0, 0),          // initialized later with correct size
 500   _compilation(c)
 501 {
 502   TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order");
 503 
 504   init_visited();
 505   count_edges(start_block, NULL);
 506 
 507   if (compilation()->is_profiling()) {
 508     ciMethod *method = compilation()->method();
 509     if (!method->is_accessor()) {
 510       ciMethodData* md = method->method_data_or_null();
 511       assert(md != NULL, "Sanity");
 512       md->set_compilation_stats(_num_loops, _num_blocks);
 513     }
 514   }
 515 
 516   if (_num_loops > 0) {
 517     mark_loops();
 518     clear_non_natural_loops(start_block);
 519     assign_loop_depth(start_block);
 520   }
 521 
 522   compute_order(start_block);
 523   compute_dominators();
 524 
 525   NOT_PRODUCT(print_blocks());
 526   DEBUG_ONLY(verify());
 527 }
 528 
 529 
 530 // Traverse the CFG:
 531 // * count total number of blocks
 532 // * count all incoming edges and backward incoming edges
 533 // * number loop header blocks
 534 // * create a list with all loop end blocks
 535 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
 536   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));
 537   assert(cur->dominator() == NULL, "dominator already initialized");
 538 
 539   if (is_active(cur)) {
 540     TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
 541     assert(is_visited(cur), "block must be visisted when block is active");
 542     assert(parent != NULL, "must have parent");
 543 
 544     cur->set(BlockBegin::linear_scan_loop_header_flag);
 545     cur->set(BlockBegin::backward_branch_target_flag);
 546 
 547     parent->set(BlockBegin::linear_scan_loop_end_flag);
 548 
 549     // When a loop header is also the start of an exception handler, then the backward branch is
 550     // an exception edge. Because such edges are usually critical edges which cannot be split, the
 551     // loop must be excluded here from processing.
 552     if (cur->is_set(BlockBegin::exception_entry_flag)) {
 553       // Make sure that dominators are correct in this weird situation
 554       _iterative_dominators = true;
 555       return;
 556     }
 557     assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
 558            "loop end blocks must have one successor (critical edges are split)");
 559 
 560     _loop_end_blocks.append(parent);
 561     return;
 562   }
 563 
 564   // increment number of incoming forward branches
 565   inc_forward_branches(cur);
 566 
 567   if (is_visited(cur)) {
 568     TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
 569     return;
 570   }
 571 
 572   _num_blocks++;
 573   set_visited(cur);
 574   set_active(cur);
 575 
 576   // recursive call for all successors
 577   int i;
 578   for (i = cur->number_of_sux() - 1; i >= 0; i--) {
 579     count_edges(cur->sux_at(i), cur);
 580   }
 581   for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
 582     count_edges(cur->exception_handler_at(i), cur);
 583   }
 584 
 585   clear_active(cur);
 586 
 587   // Each loop has a unique number.
 588   // When multiple loops are nested, assign_loop_depth assumes that the
 589   // innermost loop has the lowest number. This is guaranteed by setting
 590   // the loop number after the recursive calls for the successors above
 591   // have returned.
 592   if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
 593     assert(cur->loop_index() == -1, "cannot set loop-index twice");
 594     TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
 595 
 596     cur->set_loop_index(_num_loops);

 597     _num_loops++;
 598   }
 599 
 600   TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
 601 }
 602 
 603 
 604 void ComputeLinearScanOrder::mark_loops() {
 605   TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
 606 
 607   _loop_map = BitMap2D(_num_loops, _max_block_id);
 608   _loop_map.clear();
 609 
 610   for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
 611     BlockBegin* loop_end   = _loop_end_blocks.at(i);
 612     BlockBegin* loop_start = loop_end->sux_at(0);
 613     int         loop_idx   = loop_start->loop_index();
 614 
 615     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));
 616     assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
 617     assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
 618     assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
 619     assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
 620     assert(_work_list.is_empty(), "work list must be empty before processing");
 621 
 622     // add the end-block of the loop to the working list
 623     _work_list.push(loop_end);
 624     set_block_in_loop(loop_idx, loop_end);
 625     do {
 626       BlockBegin* cur = _work_list.pop();
 627 
 628       TRACE_LINEAR_SCAN(3, tty->print_cr("    processing B%d", cur->block_id()));
 629       assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
 630 
 631       // recursive processing of all predecessors ends when start block of loop is reached
 632       if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
 633         for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
 634           BlockBegin* pred = cur->pred_at(j);
 635 
 636           if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
 637             // this predecessor has not been processed yet, so add it to work list
 638             TRACE_LINEAR_SCAN(3, tty->print_cr("    pushing B%d", pred->block_id()));
 639             _work_list.push(pred);
 640             set_block_in_loop(loop_idx, pred);
 641           }
 642         }
 643       }
 644     } while (!_work_list.is_empty());
 645   }
 646 }
 647 
 648 
 649 // check for non-natural loops (loops where the loop header does not dominate
 650 // all other loop blocks = loops with mulitple entries).
 651 // such loops are ignored
 652 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
 653   for (int i = _num_loops - 1; i >= 0; i--) {
 654     if (is_block_in_loop(i, start_block)) {
 655       // loop i contains the entry block of the method
 656       // -> this is not a natural loop, so ignore it
 657       TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
 658 











 659       for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
 660         clear_block_in_loop(i, block_id);
 661       }
 662       _iterative_dominators = true;
 663     }
 664   }
 665 }
 666 
 667 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
 668   TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
 669   init_visited();
 670 
 671   assert(_work_list.is_empty(), "work list must be empty before processing");
 672   _work_list.append(start_block);
 673 
 674   do {
 675     BlockBegin* cur = _work_list.pop();
 676 
 677     if (!is_visited(cur)) {
 678       set_visited(cur);
 679       TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
 680 
 681       // compute loop-depth and loop-index for the block
 682       assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
 683       int i;
 684       int loop_depth = 0;
 685       int min_loop_idx = -1;
 686       for (i = _num_loops - 1; i >= 0; i--) {
 687         if (is_block_in_loop(i, cur)) {
 688           loop_depth++;
 689           min_loop_idx = i;
 690         }
 691       }
 692       cur->set_loop_depth(loop_depth);
 693       cur->set_loop_index(min_loop_idx);
 694 
 695       // append all unvisited successors to work list
 696       for (i = cur->number_of_sux() - 1; i >= 0; i--) {
 697         _work_list.append(cur->sux_at(i));
 698       }
 699       for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
 700         _work_list.append(cur->exception_handler_at(i));
 701       }
 702     }
 703   } while (!_work_list.is_empty());
 704 }
 705 
 706 
 707 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
 708   assert(a != NULL && b != NULL, "must have input blocks");
 709 
 710   _dominator_blocks.clear();
 711   while (a != NULL) {
 712     _dominator_blocks.set_bit(a->block_id());
 713     assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
 714     a = a->dominator();
 715   }
 716   while (b != NULL && !_dominator_blocks.at(b->block_id())) {
 717     assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
 718     b = b->dominator();
 719   }
 720 
 721   assert(b != NULL, "could not find dominator");
 722   return b;
 723 }
 724 
 725 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
 726   if (cur->dominator() == NULL) {
 727     TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
 728     cur->set_dominator(parent);
 729 
 730   } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
 731     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()));
 732     assert(cur->number_of_preds() > 1, "");

 733     cur->set_dominator(common_dominator(cur->dominator(), parent));
 734   }










 735 }
 736 
 737 
 738 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
 739   BlockBegin* single_sux = NULL;
 740   if (cur->number_of_sux() == 1) {
 741     single_sux = cur->sux_at(0);
 742   }
 743 
 744   // limit loop-depth to 15 bit (only for security reason, it will never be so big)
 745   int weight = (cur->loop_depth() & 0x7FFF) << 16;
 746 
 747   // general macro for short definition of weight flags
 748   // the first instance of INC_WEIGHT_IF has the highest priority
 749   int cur_bit = 15;
 750   #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
 751 
 752   // this is necessery for the (very rare) case that two successing blocks have
 753   // the same loop depth, but a different loop index (can happen for endless loops
 754   // with exception handlers)
 755   INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
 756 
 757   // loop end blocks (blocks that end with a backward branch) are added
 758   // after all other blocks of the loop.
 759   INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
 760 
 761   // critical edge split blocks are prefered because than they have a bigger
 762   // proability to be completely empty
 763   INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
 764 
 765   // exceptions should not be thrown in normal control flow, so these blocks
 766   // are added as late as possible
 767   INC_WEIGHT_IF(cur->end()->as_Throw() == NULL  && (single_sux == NULL || single_sux->end()->as_Throw()  == NULL));
 768   INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
 769 
 770   // exceptions handlers are added as late as possible
 771   INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
 772 
 773   // guarantee that weight is > 0
 774   weight |= 1;
 775 
 776   #undef INC_WEIGHT_IF
 777   assert(cur_bit >= 0, "too many flags");
 778   assert(weight > 0, "weight cannot become negative");
 779 
 780   return weight;
 781 }
 782 
 783 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
 784   // Discount the edge just traveled.
 785   // When the number drops to zero, all forward branches were processed
 786   if (dec_forward_branches(cur) != 0) {
 787     return false;
 788   }
 789 
 790   assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
 791   assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
 792   return true;
 793 }
 794 
 795 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
 796   assert(_work_list.index_of(cur) == -1, "block already in work list");
 797 
 798   int cur_weight = compute_weight(cur);
 799 
 800   // the linear_scan_number is used to cache the weight of a block
 801   cur->set_linear_scan_number(cur_weight);
 802 
 803 #ifndef PRODUCT
 804   if (StressLinearScan) {
 805     _work_list.insert_before(0, cur);
 806     return;
 807   }
 808 #endif
 809 
 810   _work_list.append(NULL); // provide space for new element
 811 
 812   int insert_idx = _work_list.length() - 1;
 813   while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
 814     _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
 815     insert_idx--;
 816   }
 817   _work_list.at_put(insert_idx, cur);
 818 
 819   TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
 820   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()));
 821 
 822 #ifdef ASSERT
 823   for (int i = 0; i < _work_list.length(); i++) {
 824     assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
 825     assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
 826   }
 827 #endif
 828 }
 829 
 830 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
 831   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()));
 832   assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
 833 
 834   // currently, the linear scan order and code emit order are equal.
 835   // therefore the linear_scan_number and the weight of a block must also
 836   // be equal.
 837   cur->set_linear_scan_number(_linear_scan_order->length());
 838   _linear_scan_order->append(cur);
 839 }
 840 
 841 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
 842   TRACE_LINEAR_SCAN(3, "----- computing final block order");
 843 
 844   // the start block is always the first block in the linear scan order
 845   _linear_scan_order = new BlockList(_num_blocks);
 846   append_block(start_block);
 847 
 848   assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
 849   BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
 850   BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
 851 
 852   BlockBegin* sux_of_osr_entry = NULL;
 853   if (osr_entry != NULL) {
 854     // special handling for osr entry:
 855     // ignore the edge between the osr entry and its successor for processing
 856     // the osr entry block is added manually below
 857     assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
 858     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");
 859 
 860     sux_of_osr_entry = osr_entry->sux_at(0);
 861     dec_forward_branches(sux_of_osr_entry);
 862 
 863     compute_dominator(osr_entry, start_block);
 864     _iterative_dominators = true;
 865   }
 866   compute_dominator(std_entry, start_block);
 867 
 868   // start processing with standard entry block
 869   assert(_work_list.is_empty(), "list must be empty before processing");
 870 
 871   if (ready_for_processing(std_entry)) {
 872     sort_into_work_list(std_entry);
 873   } else {
 874     assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
 875   }
 876 
 877   do {
 878     BlockBegin* cur = _work_list.pop();
 879 
 880     if (cur == sux_of_osr_entry) {
 881       // the osr entry block is ignored in normal processing, it is never added to the
 882       // work list. Instead, it is added as late as possible manually here.
 883       append_block(osr_entry);
 884       compute_dominator(cur, osr_entry);
 885     }
 886     append_block(cur);
 887 
 888     int i;
 889     int num_sux = cur->number_of_sux();
 890     // changed loop order to get "intuitive" order of if- and else-blocks
 891     for (i = 0; i < num_sux; i++) {
 892       BlockBegin* sux = cur->sux_at(i);
 893       compute_dominator(sux, cur);
 894       if (ready_for_processing(sux)) {
 895         sort_into_work_list(sux);
 896       }
 897     }
 898     num_sux = cur->number_of_exception_handlers();
 899     for (i = 0; i < num_sux; i++) {
 900       BlockBegin* sux = cur->exception_handler_at(i);
 901       compute_dominator(sux, cur);
 902       if (ready_for_processing(sux)) {
 903         sort_into_work_list(sux);
 904       }
 905     }
 906   } while (_work_list.length() > 0);
 907 }
 908 
 909 
 910 bool ComputeLinearScanOrder::compute_dominators_iter() {
 911   bool changed = false;
 912   int num_blocks = _linear_scan_order->length();
 913 
 914   assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
 915   assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
 916   for (int i = 1; i < num_blocks; i++) {
 917     BlockBegin* block = _linear_scan_order->at(i);
 918 
 919     BlockBegin* dominator = block->pred_at(0);
 920     int num_preds = block->number_of_preds();
 921     for (int i = 1; i < num_preds; i++) {
 922       dominator = common_dominator(dominator, block->pred_at(i));















 923     }
 924 
 925     if (dominator != block->dominator()) {
 926       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()));
 927 
 928       block->set_dominator(dominator);
 929       changed = true;
 930     }
 931   }
 932   return changed;
 933 }
 934 
 935 void ComputeLinearScanOrder::compute_dominators() {
 936   TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
 937 
 938   // iterative computation of dominators is only required for methods with non-natural loops
 939   // and OSR-methods. For all other methods, the dominators computed when generating the
 940   // linear scan block order are correct.
 941   if (_iterative_dominators) {
 942     do {
 943       TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
 944     } while (compute_dominators_iter());
 945   }
 946 
 947   // check that dominators are correct
 948   assert(!compute_dominators_iter(), "fix point not reached");















 949 }
 950 
 951 
 952 #ifndef PRODUCT
 953 void ComputeLinearScanOrder::print_blocks() {
 954   if (TraceLinearScanLevel >= 2) {
 955     tty->print_cr("----- loop information:");
 956     for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
 957       BlockBegin* cur = _linear_scan_order->at(block_idx);
 958 
 959       tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
 960       for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
 961         tty->print ("%d ", is_block_in_loop(loop_idx, cur));
 962       }
 963       tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
 964     }
 965   }
 966 
 967   if (TraceLinearScanLevel >= 1) {
 968     tty->print_cr("----- linear-scan block order:");
 969     for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
 970       BlockBegin* cur = _linear_scan_order->at(block_idx);
 971       tty->print("%4d: B%2d    loop: %2d  depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
 972 
 973       tty->print(cur->is_set(BlockBegin::exception_entry_flag)         ? " ex" : "   ");
 974       tty->print(cur->is_set(BlockBegin::critical_edge_split_flag)     ? " ce" : "   ");
 975       tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : "   ");
 976       tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag)    ? " le" : "   ");
 977 
 978       if (cur->dominator() != NULL) {
 979         tty->print("    dom: B%d ", cur->dominator()->block_id());
 980       } else {
 981         tty->print("    dom: NULL ");
 982       }
 983 
 984       if (cur->number_of_preds() > 0) {
 985         tty->print("    preds: ");
 986         for (int j = 0; j < cur->number_of_preds(); j++) {
 987           BlockBegin* pred = cur->pred_at(j);
 988           tty->print("B%d ", pred->block_id());
 989         }
 990       }
 991       if (cur->number_of_sux() > 0) {
 992         tty->print("    sux: ");
 993         for (int j = 0; j < cur->number_of_sux(); j++) {
 994           BlockBegin* sux = cur->sux_at(j);
 995           tty->print("B%d ", sux->block_id());
 996         }
 997       }
 998       if (cur->number_of_exception_handlers() > 0) {
 999         tty->print("    ex: ");
1000         for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1001           BlockBegin* ex = cur->exception_handler_at(j);
1002           tty->print("B%d ", ex->block_id());
1003         }
1004       }
1005       tty->cr();
1006     }
1007   }
1008 }
1009 #endif
1010 
1011 #ifdef ASSERT
1012 void ComputeLinearScanOrder::verify() {
1013   assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1014 
1015   if (StressLinearScan) {
1016     // blocks are scrambled when StressLinearScan is used
1017     return;
1018   }
1019 
1020   // check that all successors of a block have a higher linear-scan-number
1021   // and that all predecessors of a block have a lower linear-scan-number
1022   // (only backward branches of loops are ignored)
1023   int i;
1024   for (i = 0; i < _linear_scan_order->length(); i++) {
1025     BlockBegin* cur = _linear_scan_order->at(i);
1026 
1027     assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1028     assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1029 
1030     int j;
1031     for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1032       BlockBegin* sux = cur->sux_at(j);
1033 
1034       assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1035       if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
1036         assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1037       }
1038       if (cur->loop_depth() == sux->loop_depth()) {
1039         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");
1040       }
1041     }
1042 
1043     for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1044       BlockBegin* pred = cur->pred_at(j);
1045 
1046       assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1047       if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
1048         assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1049       }
1050       if (cur->loop_depth() == pred->loop_depth()) {
1051         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");
1052       }
1053 
1054       assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1055     }
1056 
1057     // check dominator
1058     if (i == 0) {
1059       assert(cur->dominator() == NULL, "first block has no dominator");
1060     } else {
1061       assert(cur->dominator() != NULL, "all but first block must have dominator");
1062     }
1063     assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");

1064   }
1065 
1066   // check that all loops are continuous
1067   for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1068     int block_idx = 0;
1069     assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1070 
1071     // skip blocks before the loop
1072     while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1073       block_idx++;
1074     }
1075     // skip blocks of loop
1076     while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1077       block_idx++;
1078     }
1079     // after the first non-loop block, there must not be another loop-block
1080     while (block_idx < _num_blocks) {
1081       assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1082       block_idx++;
1083     }
1084   }
1085 }
1086 #endif
1087 
1088 
1089 void IR::compute_code() {
1090   assert(is_valid(), "IR must be valid");
1091 
1092   ComputeLinearScanOrder compute_order(compilation(), start());
1093   _num_loops = compute_order.num_loops();
1094   _code = compute_order.linear_scan_order();
1095 }
1096 
1097 
1098 void IR::compute_use_counts() {
1099   // make sure all values coming out of this block get evaluated.
1100   int num_blocks = _code->length();
1101   for (int i = 0; i < num_blocks; i++) {
1102     _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1103   }
1104 
1105   // compute use counts
1106   UseCountComputer::compute(_code);
1107 }
1108 
1109 
1110 void IR::iterate_preorder(BlockClosure* closure) {
1111   assert(is_valid(), "IR must be valid");
1112   start()->iterate_preorder(closure);
1113 }
1114 
1115 
1116 void IR::iterate_postorder(BlockClosure* closure) {
1117   assert(is_valid(), "IR must be valid");
1118   start()->iterate_postorder(closure);
1119 }
1120 
1121 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1122   linear_scan_order()->iterate_forward(closure);
1123 }
1124 
1125 
1126 #ifndef PRODUCT
1127 class BlockPrinter: public BlockClosure {
1128  private:
1129   InstructionPrinter* _ip;
1130   bool                _cfg_only;
1131   bool                _live_only;
1132 
1133  public:
1134   BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1135     _ip       = ip;
1136     _cfg_only = cfg_only;
1137     _live_only = live_only;
1138   }
1139 
1140   virtual void block_do(BlockBegin* block) {
1141     if (_cfg_only) {
1142       _ip->print_instr(block); tty->cr();
1143     } else {
1144       block->print_block(*_ip, _live_only);
1145     }
1146   }
1147 };
1148 
1149 
1150 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1151   ttyLocker ttyl;
1152   InstructionPrinter ip(!cfg_only);
1153   BlockPrinter bp(&ip, cfg_only, live_only);
1154   start->iterate_preorder(&bp);
1155   tty->cr();
1156 }
1157 
1158 void IR::print(bool cfg_only, bool live_only) {
1159   if (is_valid()) {
1160     print(start(), cfg_only, live_only);
1161   } else {
1162     tty->print_cr("invalid IR");
1163   }
1164 }
1165 
1166 
1167 define_array(BlockListArray, BlockList*)
1168 define_stack(BlockListList, BlockListArray)
1169 
1170 class PredecessorValidator : public BlockClosure {
1171  private:
1172   BlockListList* _predecessors;
1173   BlockList*     _blocks;
1174 
1175   static int cmp(BlockBegin** a, BlockBegin** b) {
1176     return (*a)->block_id() - (*b)->block_id();
1177   }
1178 
1179  public:
1180   PredecessorValidator(IR* hir) {
1181     ResourceMark rm;
1182     _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1183     _blocks = new BlockList();
1184 
1185     int i;
1186     hir->start()->iterate_preorder(this);
1187     if (hir->code() != NULL) {
1188       assert(hir->code()->length() == _blocks->length(), "must match");
1189       for (i = 0; i < _blocks->length(); i++) {
1190         assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1191       }
1192     }
1193 
1194     for (i = 0; i < _blocks->length(); i++) {
1195       BlockBegin* block = _blocks->at(i);
1196       BlockList* preds = _predecessors->at(block->block_id());
1197       if (preds == NULL) {
1198         assert(block->number_of_preds() == 0, "should be the same");
1199         continue;
1200       }
1201 
1202       // clone the pred list so we can mutate it
1203       BlockList* pred_copy = new BlockList();
1204       int j;
1205       for (j = 0; j < block->number_of_preds(); j++) {
1206         pred_copy->append(block->pred_at(j));
1207       }
1208       // sort them in the same order
1209       preds->sort(cmp);
1210       pred_copy->sort(cmp);
1211       int length = MIN2(preds->length(), block->number_of_preds());
1212       for (j = 0; j < block->number_of_preds(); j++) {
1213         assert(preds->at(j) == pred_copy->at(j), "must match");
1214       }
1215 
1216       assert(preds->length() == block->number_of_preds(), "should be the same");
1217     }
1218   }
1219 
1220   virtual void block_do(BlockBegin* block) {
1221     _blocks->append(block);
1222     BlockEnd* be = block->end();
1223     int n = be->number_of_sux();
1224     int i;
1225     for (i = 0; i < n; i++) {
1226       BlockBegin* sux = be->sux_at(i);
1227       assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1228 
1229       BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1230       if (preds == NULL) {
1231         preds = new BlockList();
1232         _predecessors->at_put(sux->block_id(), preds);
1233       }
1234       preds->append(block);
1235     }
1236 
1237     n = block->number_of_exception_handlers();
1238     for (i = 0; i < n; i++) {
1239       BlockBegin* sux = block->exception_handler_at(i);
1240       assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1241 
1242       BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1243       if (preds == NULL) {
1244         preds = new BlockList();
1245         _predecessors->at_put(sux->block_id(), preds);
1246       }
1247       preds->append(block);
1248     }
1249   }
1250 };
1251 














1252 void IR::verify() {
1253 #ifdef ASSERT
1254   PredecessorValidator pv(this);


1255 #endif
1256 }
1257 
1258 #endif // PRODUCT
1259 
1260 void SubstitutionResolver::visit(Value* v) {
1261   Value v0 = *v;
1262   if (v0) {
1263     Value vs = v0->subst();
1264     if (vs != v0) {
1265       *v = v0->subst();
1266     }
1267   }
1268 }
1269 
1270 #ifdef ASSERT
1271 class SubstitutionChecker: public ValueVisitor {
1272   void visit(Value* v) {
1273     Value v0 = *v;
1274     if (v0) {
1275       Value vs = v0->subst();
1276       assert(vs == v0, "missed substitution");
1277     }
1278   }
1279 };
1280 #endif
1281 
1282 
1283 void SubstitutionResolver::block_do(BlockBegin* block) {
1284   Instruction* last = NULL;
1285   for (Instruction* n = block; n != NULL;) {
1286     n->values_do(this);
1287     // need to remove this instruction from the instruction stream
1288     if (n->subst() != n) {
1289       assert(last != NULL, "must have last");
1290       last->set_next(n->next());
1291     } else {
1292       last = n;
1293     }
1294     n = last->next();
1295   }
1296 
1297 #ifdef ASSERT
1298   SubstitutionChecker check_substitute;
1299   if (block->state()) block->state()->values_do(&check_substitute);
1300   block->block_values_do(&check_substitute);
1301   if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1302 #endif
1303 }
--- EOF ---