1 /*
   2  * Copyright 2000-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 
  26 class ciTypeFlow : public ResourceObj {
  27 private:
  28   ciEnv*    _env;
  29   ciMethod* _method;
  30   ciMethodBlocks* _methodBlocks;
  31   int       _osr_bci;
  32 
  33   // information cached from the method:
  34   int _max_locals;
  35   int _max_stack;
  36   int _code_size;
  37   bool      _has_irreducible_entry;
  38 
  39   const char* _failure_reason;
  40 
  41 public:
  42   class StateVector;
  43   class Loop;
  44   class Block;
  45 
  46   // Build a type flow analyzer
  47   // Do an OSR analysis if osr_bci >= 0.
  48   ciTypeFlow(ciEnv* env, ciMethod* method, int osr_bci = InvocationEntryBci);
  49 
  50   // Accessors
  51   ciMethod* method() const     { return _method; }
  52   ciEnv*    env()              { return _env; }
  53   Arena*    arena()            { return _env->arena(); }
  54   bool      is_osr_flow() const{ return _osr_bci != InvocationEntryBci; }
  55   int       start_bci() const  { return is_osr_flow()? _osr_bci: 0; }
  56   int       max_locals() const { return _max_locals; }
  57   int       max_stack() const  { return _max_stack; }
  58   int       max_cells() const  { return _max_locals + _max_stack; }
  59   int       code_size() const  { return _code_size; }
  60   bool      has_irreducible_entry() const { return _has_irreducible_entry; }
  61 
  62   // Represents information about an "active" jsr call.  This
  63   // class represents a call to the routine at some entry address
  64   // with some distinct return address.
  65   class JsrRecord : public ResourceObj {
  66   private:
  67     int _entry_address;
  68     int _return_address;
  69   public:
  70     JsrRecord(int entry_address, int return_address) {
  71       _entry_address = entry_address;
  72       _return_address = return_address;
  73     }
  74 
  75     int entry_address() const  { return _entry_address; }
  76     int return_address() const { return _return_address; }
  77 
  78     void print_on(outputStream* st) const {
  79 #ifndef PRODUCT
  80       st->print("%d->%d", entry_address(), return_address());
  81 #endif
  82     }
  83   };
  84 
  85   // A JsrSet represents some set of JsrRecords.  This class
  86   // is used to record a set of all jsr routines which we permit
  87   // execution to return (ret) from.
  88   //
  89   // During abstract interpretation, JsrSets are used to determine
  90   // whether two paths which reach a given block are unique, and
  91   // should be cloned apart, or are compatible, and should merge
  92   // together.
  93   //
  94   // Note that different amounts of effort can be expended determining
  95   // if paths are compatible.  <DISCUSSION>
  96   class JsrSet : public ResourceObj {
  97   private:
  98     GrowableArray<JsrRecord*>* _set;
  99 
 100     JsrRecord* record_at(int i) {
 101       return _set->at(i);
 102     }
 103 
 104     // Insert the given JsrRecord into the JsrSet, maintaining the order
 105     // of the set and replacing any element with the same entry address.
 106     void insert_jsr_record(JsrRecord* record);
 107 
 108     // Remove the JsrRecord with the given return address from the JsrSet.
 109     void remove_jsr_record(int return_address);
 110 
 111   public:
 112     JsrSet(Arena* arena, int default_len = 4);
 113 
 114     // Copy this JsrSet.
 115     void copy_into(JsrSet* jsrs);
 116 
 117     // Is this JsrSet compatible with some other JsrSet?
 118     bool is_compatible_with(JsrSet* other);
 119 
 120     // Apply the effect of a single bytecode to the JsrSet.
 121     void apply_control(ciTypeFlow* analyzer,
 122                        ciBytecodeStream* str,
 123                        StateVector* state);
 124 





 125     // What is the cardinality of this set?
 126     int size() const { return _set->length(); }
 127 
 128     void print_on(outputStream* st) const PRODUCT_RETURN;
 129   };
 130 
 131   class LocalSet VALUE_OBJ_CLASS_SPEC {
 132   private:
 133     enum Constants { max = 63 };
 134     uint64_t _bits;
 135   public:
 136     LocalSet() : _bits(0) {}
 137     void add(uint32_t i)        { if (i < (uint32_t)max) _bits |=  (1LL << i); }
 138     void add(LocalSet* ls)      { _bits |= ls->_bits; }
 139     bool test(uint32_t i) const { return i < (uint32_t)max ? (_bits>>i)&1U : true; }
 140     void clear()                { _bits = 0; }
 141     void print_on(outputStream* st, int limit) const  PRODUCT_RETURN;
 142   };
 143 
 144   // Used as a combined index for locals and temps
 145   enum Cell {
 146     Cell_0, Cell_max = INT_MAX
 147   };
 148 
 149   // A StateVector summarizes the type information at some
 150   // point in the program
 151   class StateVector : public ResourceObj {
 152   private:
 153     ciType**    _types;
 154     int         _stack_size;
 155     int         _monitor_count;
 156     ciTypeFlow* _outer;
 157 
 158     int         _trap_bci;
 159     int         _trap_index;
 160 
 161     LocalSet    _def_locals;  // For entire block
 162 
 163     static ciType* type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer);
 164 
 165   public:
 166     // Special elements in our type lattice.
 167     enum {
 168       T_TOP     = T_VOID,      // why not?
 169       T_BOTTOM  = T_CONFLICT,
 170       T_LONG2   = T_SHORT,     // 2nd word of T_LONG
 171       T_DOUBLE2 = T_CHAR,      // 2nd word of T_DOUBLE
 172       T_NULL    = T_BYTE       // for now.
 173     };
 174     static ciType* top_type()    { return ciType::make((BasicType)T_TOP); }
 175     static ciType* bottom_type() { return ciType::make((BasicType)T_BOTTOM); }
 176     static ciType* long2_type()  { return ciType::make((BasicType)T_LONG2); }
 177     static ciType* double2_type(){ return ciType::make((BasicType)T_DOUBLE2); }
 178     static ciType* null_type()   { return ciType::make((BasicType)T_NULL); }
 179 
 180     static ciType* half_type(ciType* t) {
 181       switch (t->basic_type()) {
 182       case T_LONG:    return long2_type();
 183       case T_DOUBLE:  return double2_type();
 184       default:        ShouldNotReachHere(); return NULL;
 185       }
 186     }
 187 
 188     // The meet operation for our type lattice.
 189     ciType* type_meet(ciType* t1, ciType* t2) {
 190       return type_meet_internal(t1, t2, outer());
 191     }
 192 
 193     // Accessors
 194     ciTypeFlow* outer() const          { return _outer; }
 195 
 196     int         stack_size() const     { return _stack_size; }
 197     void    set_stack_size(int ss)     { _stack_size = ss; }
 198 
 199     int         monitor_count() const  { return _monitor_count; }
 200     void    set_monitor_count(int mc)  { _monitor_count = mc; }
 201 
 202     LocalSet* def_locals() { return &_def_locals; }
 203     const LocalSet* def_locals() const { return &_def_locals; }
 204 
 205     static Cell start_cell()           { return (Cell)0; }
 206     static Cell next_cell(Cell c)      { return (Cell)(((int)c) + 1); }
 207     Cell        limit_cell() const {
 208       return (Cell)(outer()->max_locals() + stack_size());
 209     }
 210 
 211     // Cell creation
 212     Cell      local(int lnum) const {
 213       assert(lnum < outer()->max_locals(), "index check");
 214       return (Cell)(lnum);
 215     }
 216 
 217     Cell      stack(int snum) const {
 218       assert(snum < stack_size(), "index check");
 219       return (Cell)(outer()->max_locals() + snum);
 220     }
 221 
 222     Cell      tos() const { return stack(stack_size()-1); }
 223 
 224     // For external use only:
 225     ciType* local_type_at(int i) const { return type_at(local(i)); }
 226     ciType* stack_type_at(int i) const { return type_at(stack(i)); }
 227 
 228     // Accessors for the type of some Cell c
 229     ciType*   type_at(Cell c) const {
 230       assert(start_cell() <= c && c < limit_cell(), "out of bounds");
 231       return _types[c];
 232     }
 233 
 234     void      set_type_at(Cell c, ciType* type) {
 235       assert(start_cell() <= c && c < limit_cell(), "out of bounds");
 236       _types[c] = type;
 237     }
 238 
 239     // Top-of-stack operations.
 240     void      set_type_at_tos(ciType* type) { set_type_at(tos(), type); }
 241     ciType*   type_at_tos() const           { return type_at(tos()); }
 242 
 243     void      push(ciType* type) {
 244       _stack_size++;
 245       set_type_at_tos(type);
 246     }
 247     void      pop() {
 248       debug_only(set_type_at_tos(bottom_type()));
 249       _stack_size--;
 250     }
 251     ciType*   pop_value() {
 252       ciType* t = type_at_tos();
 253       pop();
 254       return t;
 255     }
 256 
 257     // Convenience operations.
 258     bool      is_reference(ciType* type) const {
 259       return type == null_type() || !type->is_primitive_type();
 260     }
 261     bool      is_int(ciType* type) const {
 262       return type->basic_type() == T_INT;
 263     }
 264     bool      is_long(ciType* type) const {
 265       return type->basic_type() == T_LONG;
 266     }
 267     bool      is_float(ciType* type) const {
 268       return type->basic_type() == T_FLOAT;
 269     }
 270     bool      is_double(ciType* type) const {
 271       return type->basic_type() == T_DOUBLE;
 272     }
 273 
 274     void store_to_local(int lnum) {
 275       _def_locals.add((uint) lnum);
 276     }
 277 
 278     void      push_translate(ciType* type);
 279 
 280     void      push_int() {
 281       push(ciType::make(T_INT));
 282     }
 283     void      pop_int() {
 284       assert(is_int(type_at_tos()), "must be integer");
 285       pop();
 286     }
 287     void      check_int(Cell c) {
 288       assert(is_int(type_at(c)), "must be integer");
 289     }
 290     void      push_double() {
 291       push(ciType::make(T_DOUBLE));
 292       push(double2_type());
 293     }
 294     void      pop_double() {
 295       assert(type_at_tos() == double2_type(), "must be 2nd half");
 296       pop();
 297       assert(is_double(type_at_tos()), "must be double");
 298       pop();
 299     }
 300     void      push_float() {
 301       push(ciType::make(T_FLOAT));
 302     }
 303     void      pop_float() {
 304       assert(is_float(type_at_tos()), "must be float");
 305       pop();
 306     }
 307     void      push_long() {
 308       push(ciType::make(T_LONG));
 309       push(long2_type());
 310     }
 311     void      pop_long() {
 312       assert(type_at_tos() == long2_type(), "must be 2nd half");
 313       pop();
 314       assert(is_long(type_at_tos()), "must be long");
 315       pop();
 316     }
 317     void      push_object(ciKlass* klass) {
 318       push(klass);
 319     }
 320     void      pop_object() {
 321       assert(is_reference(type_at_tos()), "must be reference type");
 322       pop();
 323     }
 324     void      pop_array() {
 325       assert(type_at_tos() == null_type() ||
 326              type_at_tos()->is_array_klass(), "must be array type");
 327       pop();
 328     }
 329     // pop_objArray and pop_typeArray narrow the tos to ciObjArrayKlass
 330     // or ciTypeArrayKlass (resp.).  In the rare case that an explicit
 331     // null is popped from the stack, we return NULL.  Caller beware.
 332     ciObjArrayKlass* pop_objArray() {
 333       ciType* array = pop_value();
 334       if (array == null_type())  return NULL;
 335       assert(array->is_obj_array_klass(), "must be object array type");
 336       return array->as_obj_array_klass();
 337     }
 338     ciTypeArrayKlass* pop_typeArray() {
 339       ciType* array = pop_value();
 340       if (array == null_type())  return NULL;
 341       assert(array->is_type_array_klass(), "must be prim array type");
 342       return array->as_type_array_klass();
 343     }
 344     void      push_null() {
 345       push(null_type());
 346     }
 347     void      do_null_assert(ciKlass* unloaded_klass);
 348 
 349     // Helper convenience routines.
 350     void do_aaload(ciBytecodeStream* str);
 351     void do_checkcast(ciBytecodeStream* str);
 352     void do_getfield(ciBytecodeStream* str);
 353     void do_getstatic(ciBytecodeStream* str);
 354     void do_invoke(ciBytecodeStream* str, bool has_receiver);
 355     void do_jsr(ciBytecodeStream* str);
 356     void do_ldc(ciBytecodeStream* str);
 357     void do_multianewarray(ciBytecodeStream* str);
 358     void do_new(ciBytecodeStream* str);
 359     void do_newarray(ciBytecodeStream* str);
 360     void do_putfield(ciBytecodeStream* str);
 361     void do_putstatic(ciBytecodeStream* str);
 362     void do_ret(ciBytecodeStream* str);
 363 
 364     void overwrite_local_double_long(int index) {
 365       // Invalidate the previous local if it contains first half of
 366       // a double or long value since it's seconf half is being overwritten.
 367       int prev_index = index - 1;
 368       if (prev_index >= 0 &&
 369           (is_double(type_at(local(prev_index))) ||
 370            is_long(type_at(local(prev_index))))) {
 371         set_type_at(local(prev_index), bottom_type());
 372       }
 373     }
 374 
 375     void load_local_object(int index) {
 376       ciType* type = type_at(local(index));
 377       assert(is_reference(type), "must be reference type");
 378       push(type);
 379     }
 380     void store_local_object(int index) {
 381       ciType* type = pop_value();
 382       assert(is_reference(type) || type->is_return_address(),
 383              "must be reference type or return address");
 384       overwrite_local_double_long(index);
 385       set_type_at(local(index), type);
 386       store_to_local(index);
 387     }
 388 
 389     void load_local_double(int index) {
 390       ciType* type = type_at(local(index));
 391       ciType* type2 = type_at(local(index+1));
 392       assert(is_double(type), "must be double type");
 393       assert(type2 == double2_type(), "must be 2nd half");
 394       push(type);
 395       push(double2_type());
 396     }
 397     void store_local_double(int index) {
 398       ciType* type2 = pop_value();
 399       ciType* type = pop_value();
 400       assert(is_double(type), "must be double");
 401       assert(type2 == double2_type(), "must be 2nd half");
 402       overwrite_local_double_long(index);
 403       set_type_at(local(index), type);
 404       set_type_at(local(index+1), type2);
 405       store_to_local(index);
 406       store_to_local(index+1);
 407     }
 408 
 409     void load_local_float(int index) {
 410       ciType* type = type_at(local(index));
 411       assert(is_float(type), "must be float type");
 412       push(type);
 413     }
 414     void store_local_float(int index) {
 415       ciType* type = pop_value();
 416       assert(is_float(type), "must be float type");
 417       overwrite_local_double_long(index);
 418       set_type_at(local(index), type);
 419       store_to_local(index);
 420     }
 421 
 422     void load_local_int(int index) {
 423       ciType* type = type_at(local(index));
 424       assert(is_int(type), "must be int type");
 425       push(type);
 426     }
 427     void store_local_int(int index) {
 428       ciType* type = pop_value();
 429       assert(is_int(type), "must be int type");
 430       overwrite_local_double_long(index);
 431       set_type_at(local(index), type);
 432       store_to_local(index);
 433     }
 434 
 435     void load_local_long(int index) {
 436       ciType* type = type_at(local(index));
 437       ciType* type2 = type_at(local(index+1));
 438       assert(is_long(type), "must be long type");
 439       assert(type2 == long2_type(), "must be 2nd half");
 440       push(type);
 441       push(long2_type());
 442     }
 443     void store_local_long(int index) {
 444       ciType* type2 = pop_value();
 445       ciType* type = pop_value();
 446       assert(is_long(type), "must be long");
 447       assert(type2 == long2_type(), "must be 2nd half");
 448       overwrite_local_double_long(index);
 449       set_type_at(local(index), type);
 450       set_type_at(local(index+1), type2);
 451       store_to_local(index);
 452       store_to_local(index+1);
 453     }
 454 
 455     // Stop interpretation of this path with a trap.
 456     void trap(ciBytecodeStream* str, ciKlass* klass, int index);
 457 
 458   public:
 459     StateVector(ciTypeFlow* outer);
 460 
 461     // Copy our value into some other StateVector
 462     void copy_into(StateVector* copy) const;
 463 
 464     // Meets this StateVector with another, destructively modifying this
 465     // one.  Returns true if any modification takes place.
 466     bool meet(const StateVector* incoming);
 467 
 468     // Ditto, except that the incoming state is coming from an exception.
 469     bool meet_exception(ciInstanceKlass* exc, const StateVector* incoming);
 470 
 471     // Apply the effect of one bytecode to this StateVector
 472     bool apply_one_bytecode(ciBytecodeStream* stream);
 473 
 474     // What is the bci of the trap?
 475     int  trap_bci() { return _trap_bci; }
 476 
 477     // What is the index associated with the trap?
 478     int  trap_index() { return _trap_index; }
 479 
 480     void print_cell_on(outputStream* st, Cell c) const PRODUCT_RETURN;
 481     void print_on(outputStream* st) const              PRODUCT_RETURN;
 482   };
 483 
 484   // Parameter for "find_block" calls:
 485   // Describes the difference between a public and backedge copy.
 486   enum CreateOption {
 487     create_public_copy,
 488     create_backedge_copy,
 489     no_create
 490   };
 491 
 492   // Successor iterator
 493   class SuccIter : public StackObj {
 494   private:
 495     Block* _pred;
 496     int    _index;
 497     Block* _succ;
 498   public:
 499     SuccIter()                        : _pred(NULL), _index(-1), _succ(NULL) {}
 500     SuccIter(Block* pred)             : _pred(pred), _index(-1), _succ(NULL) { next(); }
 501     int    index()     { return _index; }
 502     Block* pred()      { return _pred; }           // Return predecessor
 503     bool   done()      { return _index < 0; }      // Finished?
 504     Block* succ()      { return _succ; }           // Return current successor
 505     void   next();                                 // Advance
 506     void   set_succ(Block* succ);                  // Update current successor
 507     bool   is_normal_ctrl() { return index() < _pred->successors()->length(); }
 508   };
 509 
 510   // A basic block
 511   class Block : public ResourceObj {
 512   private:
 513     ciBlock*                          _ciblock;
 514     GrowableArray<Block*>*           _exceptions;
 515     GrowableArray<ciInstanceKlass*>* _exc_klasses;
 516     GrowableArray<Block*>*           _successors;
 517     StateVector*                     _state;
 518     JsrSet*                          _jsrs;
 519 
 520     int                              _trap_bci;
 521     int                              _trap_index;
 522 
 523     // pre_order, assigned at first visit. Used as block ID and "visited" tag
 524     int                              _pre_order;
 525 
 526     // A post-order, used to compute the reverse post order (RPO) provided to the client
 527     int                              _post_order;  // used to compute rpo
 528 
 529     // Has this block been cloned for a loop backedge?
 530     bool                             _backedge_copy;
 531 
 532     // A pointer used for our internal work list
 533     Block*                           _next;
 534     bool                             _on_work_list;      // on the work list
 535     Block*                           _rpo_next;          // Reverse post order list
 536 
 537     // Loop info
 538     Loop*                            _loop;              // nearest loop
 539     bool                             _irreducible_entry; // entry to irreducible loop
 540     bool                             _exception_entry;   // entry to exception handler
 541 
 542     ciBlock*     ciblock() const     { return _ciblock; }
 543     StateVector* state() const     { return _state; }
 544 
 545     // Compute the exceptional successors and types for this Block.
 546     void compute_exceptions();
 547 
 548   public:
 549     // constructors
 550     Block(ciTypeFlow* outer, ciBlock* ciblk, JsrSet* jsrs);
 551 
 552     void set_trap(int trap_bci, int trap_index) {
 553       _trap_bci = trap_bci;
 554       _trap_index = trap_index;
 555       assert(has_trap(), "");
 556     }
 557     bool has_trap()   const  { return _trap_bci != -1; }
 558     int  trap_bci()   const  { assert(has_trap(), ""); return _trap_bci; }
 559     int  trap_index() const  { assert(has_trap(), ""); return _trap_index; }
 560 
 561     // accessors
 562     ciTypeFlow* outer() const { return state()->outer(); }
 563     int start() const         { return _ciblock->start_bci(); }
 564     int limit() const         { return _ciblock->limit_bci(); }
 565     int control() const       { return _ciblock->control_bci(); }
 566     JsrSet* jsrs() const      { return _jsrs; }
 567 
 568     bool    is_backedge_copy() const       { return _backedge_copy; }
 569     void   set_backedge_copy(bool z);
 570     int        backedge_copy_count() const { return outer()->backedge_copy_count(ciblock()->index(), _jsrs); }
 571 
 572     // access to entry state
 573     int     stack_size() const         { return _state->stack_size(); }
 574     int     monitor_count() const      { return _state->monitor_count(); }
 575     ciType* local_type_at(int i) const { return _state->local_type_at(i); }
 576     ciType* stack_type_at(int i) const { return _state->stack_type_at(i); }
 577 
 578     // Data flow on locals
 579     bool is_invariant_local(uint v) const {
 580       assert(is_loop_head(), "only loop heads");
 581       // Find outermost loop with same loop head
 582       Loop* lp = loop();
 583       while (lp->parent() != NULL) {
 584         if (lp->parent()->head() != lp->head()) break;
 585         lp = lp->parent();
 586       }
 587       return !lp->def_locals()->test(v);
 588     }
 589     LocalSet* def_locals() { return _state->def_locals(); }
 590     const LocalSet* def_locals() const { return _state->def_locals(); }
 591 
 592     // Get the successors for this Block.
 593     GrowableArray<Block*>* successors(ciBytecodeStream* str,
 594                                       StateVector* state,
 595                                       JsrSet* jsrs);
 596     GrowableArray<Block*>* successors() {
 597       assert(_successors != NULL, "must be filled in");
 598       return _successors;
 599     }
 600 
 601     // Get the exceptional successors for this Block.
 602     GrowableArray<Block*>* exceptions() {
 603       if (_exceptions == NULL) {
 604         compute_exceptions();
 605       }
 606       return _exceptions;
 607     }
 608 
 609     // Get the exception klasses corresponding to the
 610     // exceptional successors for this Block.
 611     GrowableArray<ciInstanceKlass*>* exc_klasses() {
 612       if (_exc_klasses == NULL) {
 613         compute_exceptions();
 614       }
 615       return _exc_klasses;
 616     }
 617 
 618     // Is this Block compatible with a given JsrSet?
 619     bool is_compatible_with(JsrSet* other) {
 620       return _jsrs->is_compatible_with(other);
 621     }
 622 
 623     // Copy the value of our state vector into another.
 624     void copy_state_into(StateVector* copy) const {
 625       _state->copy_into(copy);
 626     }
 627 
 628     // Copy the value of our JsrSet into another
 629     void copy_jsrs_into(JsrSet* copy) const {
 630       _jsrs->copy_into(copy);
 631     }
 632 




 633     // Meets the start state of this block with another state, destructively
 634     // modifying this one.  Returns true if any modification takes place.
 635     bool meet(const StateVector* incoming) {
 636       return state()->meet(incoming);
 637     }
 638 
 639     // Ditto, except that the incoming state is coming from an
 640     // exception path.  This means the stack is replaced by the
 641     // appropriate exception type.
 642     bool meet_exception(ciInstanceKlass* exc, const StateVector* incoming) {
 643       return state()->meet_exception(exc, incoming);
 644     }
 645 
 646     // Work list manipulation
 647     void   set_next(Block* block) { _next = block; }
 648     Block* next() const           { return _next; }
 649 
 650     void   set_on_work_list(bool c) { _on_work_list = c; }
 651     bool   is_on_work_list() const  { return _on_work_list; }
 652 
 653     bool   has_pre_order() const  { return _pre_order >= 0; }
 654     void   set_pre_order(int po)  { assert(!has_pre_order(), ""); _pre_order = po; }
 655     int    pre_order() const      { assert(has_pre_order(), ""); return _pre_order; }
 656     void   set_next_pre_order()   { set_pre_order(outer()->inc_next_pre_order()); }
 657     bool   is_start() const       { return _pre_order == outer()->start_block_num(); }
 658 
 659     // Reverse post order
 660     void   df_init();
 661     bool   has_post_order() const { return _post_order >= 0; }
 662     void   set_post_order(int po) { assert(!has_post_order() && po >= 0, ""); _post_order = po; }
 663     void   reset_post_order(int o){ _post_order = o; }
 664     int    post_order() const     { assert(has_post_order(), ""); return _post_order; }
 665 
 666     bool   has_rpo() const        { return has_post_order() && outer()->have_block_count(); }
 667     int    rpo() const            { assert(has_rpo(), ""); return outer()->block_count() - post_order() - 1; }
 668     void   set_rpo_next(Block* b) { _rpo_next = b; }
 669     Block* rpo_next()             { return _rpo_next; }
 670 
 671     // Loops
 672     Loop*  loop() const                  { return _loop; }
 673     void   set_loop(Loop* lp)            { _loop = lp; }
 674     bool   is_loop_head() const          { return _loop && _loop->head() == this; }
 675     void   set_irreducible_entry(bool c) { _irreducible_entry = c; }
 676     bool   is_irreducible_entry() const  { return _irreducible_entry; }
 677     bool   is_visited() const            { return has_pre_order(); }
 678     bool   is_post_visited() const       { return has_post_order(); }
 679     bool   is_clonable_exit(Loop* lp);
 680     Block* looping_succ(Loop* lp);       // Successor inside of loop
 681     bool   is_single_entry_loop_head() const {
 682       if (!is_loop_head()) return false;
 683       for (Loop* lp = loop(); lp != NULL && lp->head() == this; lp = lp->parent())
 684         if (lp->is_irreducible()) return false;
 685       return true;
 686     }
 687 
 688     void   print_value_on(outputStream* st) const PRODUCT_RETURN;
 689     void   print_on(outputStream* st) const       PRODUCT_RETURN;
 690   };
 691 
 692   // Loop
 693   class Loop : public ResourceObj {
 694   private:
 695     Loop* _parent;
 696     Loop* _sibling;  // List of siblings, null terminated
 697     Loop* _child;    // Head of child list threaded thru sibling pointer
 698     Block* _head;    // Head of loop
 699     Block* _tail;    // Tail of loop
 700     bool   _irreducible;
 701     LocalSet _def_locals;
 702 
 703   public:
 704     Loop(Block* head, Block* tail) :
 705       _head(head),   _tail(tail),
 706       _parent(NULL), _sibling(NULL), _child(NULL),
 707       _irreducible(false), _def_locals() {}
 708 
 709     Loop* parent()  const { return _parent; }
 710     Loop* sibling() const { return _sibling; }
 711     Loop* child()   const { return _child; }
 712     Block* head()   const { return _head; }
 713     Block* tail()   const { return _tail; }
 714     void set_parent(Loop* p)  { _parent = p; }
 715     void set_sibling(Loop* s) { _sibling = s; }
 716     void set_child(Loop* c)   { _child = c; }
 717     void set_head(Block* hd)  { _head = hd; }
 718     void set_tail(Block* tl)  { _tail = tl; }
 719 
 720     int depth() const;              // nesting depth
 721 
 722     // Returns true if lp is a nested loop or us.
 723     bool contains(Loop* lp) const;
 724     bool contains(Block* blk) const { return contains(blk->loop()); }
 725 
 726     // Data flow on locals
 727     LocalSet* def_locals() { return &_def_locals; }
 728     const LocalSet* def_locals() const { return &_def_locals; }
 729 
 730     // Merge the branch lp into this branch, sorting on the loop head
 731     // pre_orders. Returns the new branch.
 732     Loop* sorted_merge(Loop* lp);
 733 
 734     // Mark non-single entry to loop
 735     void set_irreducible(Block* entry) {
 736       _irreducible = true;
 737       entry->set_irreducible_entry(true);
 738     }
 739     bool is_irreducible() const { return _irreducible; }
 740 
 741     bool is_root() const { return _tail->pre_order() == max_jint; }
 742 
 743     void print(outputStream* st = tty, int indent = 0) const PRODUCT_RETURN;
 744   };
 745 
 746   // Postorder iteration over the loop tree.
 747   class PostorderLoops : public StackObj {
 748   private:
 749     Loop* _root;
 750     Loop* _current;
 751   public:
 752     PostorderLoops(Loop* root) : _root(root), _current(root) {
 753       while (_current->child() != NULL) {
 754         _current = _current->child();
 755       }
 756     }
 757     bool done() { return _current == NULL; }  // Finished iterating?
 758     void next();                            // Advance to next loop
 759     Loop* current() { return _current; }      // Return current loop.
 760   };
 761 
 762   // Preorder iteration over the loop tree.
 763   class PreorderLoops : public StackObj {
 764   private:
 765     Loop* _root;
 766     Loop* _current;
 767   public:
 768     PreorderLoops(Loop* root) : _root(root), _current(root) {}
 769     bool done() { return _current == NULL; }  // Finished iterating?
 770     void next();                            // Advance to next loop
 771     Loop* current() { return _current; }      // Return current loop.
 772   };
 773 
 774   // Standard indexes of successors, for various bytecodes.
 775   enum {
 776     FALL_THROUGH   = 0,  // normal control
 777     IF_NOT_TAKEN   = 0,  // the not-taken branch of an if (i.e., fall-through)
 778     IF_TAKEN       = 1,  // the taken branch of an if
 779     GOTO_TARGET    = 0,  // unique successor for goto, jsr, or ret
 780     SWITCH_DEFAULT = 0,  // default branch of a switch
 781     SWITCH_CASES   = 1   // first index for any non-default switch branches
 782     // Unlike in other blocks, the successors of a switch are listed uniquely.
 783   };
 784 
 785 private:
 786   // A mapping from pre_order to Blocks.  This array is created
 787   // only at the end of the flow.
 788   Block** _block_map;
 789 
 790   // For each ciBlock index, a list of Blocks which share this ciBlock.
 791   GrowableArray<Block*>** _idx_to_blocklist;
 792   // count of ciBlocks
 793   int _ciblock_count;
 794 
 795   // Tells if a given instruction is able to generate an exception edge.
 796   bool can_trap(ciBytecodeStream& str);
 797 
 798   // Clone the loop heads. Returns true if any cloning occurred.
 799   bool clone_loop_heads(Loop* lp, StateVector* temp_vector, JsrSet* temp_set);
 800 
 801   // Clone lp's head and replace tail's successors with clone.
 802   Block* clone_loop_head(Loop* lp, StateVector* temp_vector, JsrSet* temp_set);
 803 
 804 public:
 805   // Return the block beginning at bci which has a JsrSet compatible
 806   // with jsrs.
 807   Block* block_at(int bci, JsrSet* set, CreateOption option = create_public_copy);
 808 
 809   // block factory
 810   Block* get_block_for(int ciBlockIndex, JsrSet* jsrs, CreateOption option = create_public_copy);
 811 
 812   // How many of the blocks have the backedge_copy bit set?
 813   int backedge_copy_count(int ciBlockIndex, JsrSet* jsrs) const;
 814 
 815   // Return an existing block containing bci which has a JsrSet compatible
 816   // with jsrs, or NULL if there is none.
 817   Block* existing_block_at(int bci, JsrSet* set) { return block_at(bci, set, no_create); }
 818 
 819   // Tell whether the flow analysis has encountered an error of some sort.
 820   bool failing() { return env()->failing() || _failure_reason != NULL; }
 821 
 822   // Reason this compilation is failing, such as "too many basic blocks".
 823   const char* failure_reason() { return _failure_reason; }
 824 
 825   // Note a failure.
 826   void record_failure(const char* reason);
 827 
 828   // Return the block of a given pre-order number.
 829   int have_block_count() const      { return _block_map != NULL; }
 830   int block_count() const           { assert(have_block_count(), "");
 831                                       return _next_pre_order; }
 832   Block* pre_order_at(int po) const { assert(0 <= po && po < block_count(), "out of bounds");
 833                                       return _block_map[po]; }
 834   Block* start_block() const        { return pre_order_at(start_block_num()); }
 835   int start_block_num() const       { return 0; }
 836   Block* rpo_at(int rpo) const      { assert(0 <= rpo && rpo < block_count(), "out of bounds");
 837                                       return _block_map[rpo]; }
 838   int next_pre_order()              { return _next_pre_order; }
 839   int inc_next_pre_order()          { return _next_pre_order++; }
 840 
 841 private:
 842   // A work list used during flow analysis.
 843   Block* _work_list;
 844 
 845   // List of blocks in reverse post order
 846   Block* _rpo_list;
 847 
 848   // Next Block::_pre_order.  After mapping, doubles as block_count.
 849   int _next_pre_order;
 850 
 851   // Are there more blocks on the work list?
 852   bool work_list_empty() { return _work_list == NULL; }
 853 
 854   // Get the next basic block from our work list.
 855   Block* work_list_next();
 856 
 857   // Add a basic block to our work list.
 858   void add_to_work_list(Block* block);
 859 
 860   // Prepend a basic block to rpo list.
 861   void prepend_to_rpo_list(Block* blk) {
 862     blk->set_rpo_next(_rpo_list);
 863     _rpo_list = blk;
 864   }
 865 
 866   // Root of the loop tree
 867   Loop* _loop_tree_root;
 868 
 869   // State used for make_jsr_record
 870   int _jsr_count;
 871   GrowableArray<JsrRecord*>* _jsr_records;
 872 
 873 public:
 874   // Make a JsrRecord for a given (entry, return) pair, if such a record
 875   // does not already exist.
 876   JsrRecord* make_jsr_record(int entry_address, int return_address);
 877 
 878   void  set_loop_tree_root(Loop* ltr) { _loop_tree_root = ltr; }
 879   Loop* loop_tree_root()              { return _loop_tree_root; }
 880 
 881 private:
 882   // Get the initial state for start_bci:
 883   const StateVector* get_start_state();
 884 
 885   // Merge the current state into all exceptional successors at the
 886   // current point in the code.
 887   void flow_exceptions(GrowableArray<Block*>* exceptions,
 888                        GrowableArray<ciInstanceKlass*>* exc_klasses,
 889                        StateVector* state);
 890 
 891   // Merge the current state into all successors at the current point
 892   // in the code.
 893   void flow_successors(GrowableArray<Block*>* successors,
 894                        StateVector* state);
 895 
 896   // Interpret the effects of the bytecodes on the incoming state
 897   // vector of a basic block.  Push the changed state to succeeding
 898   // basic blocks.
 899   void flow_block(Block* block,
 900                   StateVector* scratch_state,
 901                   JsrSet* scratch_jsrs);
 902 
 903   // Perform the type flow analysis, creating and cloning Blocks as
 904   // necessary.
 905   void flow_types();
 906 
 907   // Perform the depth first type flow analysis. Helper for flow_types.
 908   void df_flow_types(Block* start,
 909                      bool do_flow,
 910                      StateVector* temp_vector,
 911                      JsrSet* temp_set);
 912 
 913   // Incrementally build loop tree.
 914   void build_loop_tree(Block* blk);
 915 
 916   // Create the block map, which indexes blocks in pre_order.
 917   void map_blocks();
 918 
 919 public:
 920   // Perform type inference flow analysis.
 921   void do_flow();
 922 
 923   void print_on(outputStream* st) const PRODUCT_RETURN;
 924 
 925   void rpo_print_on(outputStream* st) const PRODUCT_RETURN;
 926 };
--- EOF ---