1 /*
   2  * Copyright (c) 2000, 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 #ifndef SHARE_VM_CI_CITYPEFLOW_HPP
  26 #define SHARE_VM_CI_CITYPEFLOW_HPP
  27 
  28 #ifdef COMPILER2
  29 #include "ci/ciEnv.hpp"
  30 #include "ci/ciKlass.hpp"
  31 #include "ci/ciMethodBlocks.hpp"
  32 #endif
  33 #ifdef SHARK
  34 #include "ci/ciEnv.hpp"
  35 #include "ci/ciKlass.hpp"
  36 #include "ci/ciMethodBlocks.hpp"
  37 #include "shark/shark_globals.hpp"
  38 #endif
  39 
  40 
  41 class ciTypeFlow : public ResourceObj {
  42 private:
  43   ciEnv*    _env;
  44   ciMethod* _method;
  45   ciMethodBlocks* _methodBlocks;
  46   int       _osr_bci;
  47 
  48   // information cached from the method:
  49   int _max_locals;
  50   int _max_stack;
  51   int _code_size;
  52   bool      _has_irreducible_entry;
  53 
  54   const char* _failure_reason;
  55 
  56 public:
  57   class StateVector;
  58   class Loop;
  59   class Block;
  60 
  61   // Build a type flow analyzer
  62   // Do an OSR analysis if osr_bci >= 0.
  63   ciTypeFlow(ciEnv* env, ciMethod* method, int osr_bci = InvocationEntryBci);
  64 
  65   // Accessors
  66   ciMethod* method() const     { return _method; }
  67   ciEnv*    env()              { return _env; }
  68   Arena*    arena()            { return _env->arena(); }
  69   bool      is_osr_flow() const{ return _osr_bci != InvocationEntryBci; }
  70   int       start_bci() const  { return is_osr_flow()? _osr_bci: 0; }
  71   int       max_locals() const { return _max_locals; }
  72   int       max_stack() const  { return _max_stack; }
  73   int       max_cells() const  { return _max_locals + _max_stack; }
  74   int       code_size() const  { return _code_size; }
  75   bool      has_irreducible_entry() const { return _has_irreducible_entry; }
  76 
  77   // Represents information about an "active" jsr call.  This
  78   // class represents a call to the routine at some entry address
  79   // with some distinct return address.
  80   class JsrRecord : public ResourceObj {
  81   private:
  82     int _entry_address;
  83     int _return_address;
  84   public:
  85     JsrRecord(int entry_address, int return_address) {
  86       _entry_address = entry_address;
  87       _return_address = return_address;
  88     }
  89 
  90     int entry_address() const  { return _entry_address; }
  91     int return_address() const { return _return_address; }
  92 
  93     void print_on(outputStream* st) const {
  94 #ifndef PRODUCT
  95       st->print("%d->%d", entry_address(), return_address());
  96 #endif
  97     }
  98   };
  99 
 100   // A JsrSet represents some set of JsrRecords.  This class
 101   // is used to record a set of all jsr routines which we permit
 102   // execution to return (ret) from.
 103   //
 104   // During abstract interpretation, JsrSets are used to determine
 105   // whether two paths which reach a given block are unique, and
 106   // should be cloned apart, or are compatible, and should merge
 107   // together.
 108   //
 109   // Note that different amounts of effort can be expended determining
 110   // if paths are compatible.  <DISCUSSION>
 111   class JsrSet : public ResourceObj {
 112   private:
 113     GrowableArray<JsrRecord*>* _set;
 114 
 115     JsrRecord* record_at(int i) {
 116       return _set->at(i);
 117     }
 118 
 119     // Insert the given JsrRecord into the JsrSet, maintaining the order
 120     // of the set and replacing any element with the same entry address.
 121     void insert_jsr_record(JsrRecord* record);
 122 
 123     // Remove the JsrRecord with the given return address from the JsrSet.
 124     void remove_jsr_record(int return_address);
 125 
 126   public:
 127     JsrSet(Arena* arena, int default_len = 4);
 128 
 129     // Copy this JsrSet.
 130     void copy_into(JsrSet* jsrs);
 131 
 132     // Is this JsrSet compatible with some other JsrSet?
 133     bool is_compatible_with(JsrSet* other);
 134 
 135     // Apply the effect of a single bytecode to the JsrSet.
 136     void apply_control(ciTypeFlow* analyzer,
 137                        ciBytecodeStream* str,
 138                        StateVector* state);
 139 
 140     // What is the cardinality of this set?
 141     int size() const { return _set->length(); }
 142 
 143     void print_on(outputStream* st) const PRODUCT_RETURN;
 144   };
 145 
 146   class LocalSet VALUE_OBJ_CLASS_SPEC {
 147   private:
 148     enum Constants { max = 63 };
 149     uint64_t _bits;
 150   public:
 151     LocalSet() : _bits(0) {}
 152     void add(uint32_t i)        { if (i < (uint32_t)max) _bits |=  (1LL << i); }
 153     void add(LocalSet* ls)      { _bits |= ls->_bits; }
 154     bool test(uint32_t i) const { return i < (uint32_t)max ? (_bits>>i)&1U : true; }
 155     void clear()                { _bits = 0; }
 156     void print_on(outputStream* st, int limit) const  PRODUCT_RETURN;
 157   };
 158 
 159   // Used as a combined index for locals and temps
 160   enum Cell {
 161     Cell_0, Cell_max = INT_MAX
 162   };
 163 
 164   // A StateVector summarizes the type information at some
 165   // point in the program
 166   class StateVector : public ResourceObj {
 167   private:
 168     ciType**    _types;
 169     int         _stack_size;
 170     int         _monitor_count;
 171     ciTypeFlow* _outer;
 172 
 173     int         _trap_bci;
 174     int         _trap_index;
 175 
 176     LocalSet    _def_locals;  // For entire block
 177 
 178     static ciType* type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer);
 179 
 180   public:
 181     // Special elements in our type lattice.
 182     enum {
 183       T_TOP     = T_VOID,      // why not?
 184       T_BOTTOM  = T_CONFLICT,
 185       T_LONG2   = T_SHORT,     // 2nd word of T_LONG
 186       T_DOUBLE2 = T_CHAR,      // 2nd word of T_DOUBLE
 187       T_NULL    = T_BYTE       // for now.
 188     };
 189     static ciType* top_type()    { return ciType::make((BasicType)T_TOP); }
 190     static ciType* bottom_type() { return ciType::make((BasicType)T_BOTTOM); }
 191     static ciType* long2_type()  { return ciType::make((BasicType)T_LONG2); }
 192     static ciType* double2_type(){ return ciType::make((BasicType)T_DOUBLE2); }
 193     static ciType* null_type()   { return ciType::make((BasicType)T_NULL); }
 194 
 195     static ciType* half_type(ciType* t) {
 196       switch (t->basic_type()) {
 197       case T_LONG:    return long2_type();
 198       case T_DOUBLE:  return double2_type();
 199       default:        ShouldNotReachHere(); return NULL;
 200       }
 201     }
 202 
 203     // The meet operation for our type lattice.
 204     ciType* type_meet(ciType* t1, ciType* t2) {
 205       return type_meet_internal(t1, t2, outer());
 206     }
 207 
 208     // Accessors
 209     ciTypeFlow* outer() const          { return _outer; }
 210 
 211     int         stack_size() const     { return _stack_size; }
 212     void    set_stack_size(int ss)     { _stack_size = ss; }
 213 
 214     int         monitor_count() const  { return _monitor_count; }
 215     void    set_monitor_count(int mc)  { _monitor_count = mc; }
 216 
 217     LocalSet* def_locals() { return &_def_locals; }
 218     const LocalSet* def_locals() const { return &_def_locals; }
 219 
 220     static Cell start_cell()           { return (Cell)0; }
 221     static Cell next_cell(Cell c)      { return (Cell)(((int)c) + 1); }
 222     Cell        limit_cell() const {
 223       return (Cell)(outer()->max_locals() + stack_size());
 224     }
 225 
 226     // Cell creation
 227     Cell      local(int lnum) const {
 228       assert(lnum < outer()->max_locals(), "index check");
 229       return (Cell)(lnum);
 230     }
 231 
 232     Cell      stack(int snum) const {
 233       assert(snum < stack_size(), "index check");
 234       return (Cell)(outer()->max_locals() + snum);
 235     }
 236 
 237     Cell      tos() const { return stack(stack_size()-1); }
 238 
 239     // For external use only:
 240     ciType* local_type_at(int i) const { return type_at(local(i)); }
 241     ciType* stack_type_at(int i) const { return type_at(stack(i)); }
 242 
 243     // Accessors for the type of some Cell c
 244     ciType*   type_at(Cell c) const {
 245       assert(start_cell() <= c && c < limit_cell(), "out of bounds");
 246       return _types[c];
 247     }
 248 
 249     void      set_type_at(Cell c, ciType* type) {
 250       assert(start_cell() <= c && c < limit_cell(), "out of bounds");
 251       _types[c] = type;
 252     }
 253 
 254     // Top-of-stack operations.
 255     void      set_type_at_tos(ciType* type) { set_type_at(tos(), type); }
 256     ciType*   type_at_tos() const           { return type_at(tos()); }
 257 
 258     void      push(ciType* type) {
 259       _stack_size++;
 260       set_type_at_tos(type);
 261     }
 262     void      pop() {
 263       debug_only(set_type_at_tos(bottom_type()));
 264       _stack_size--;
 265     }
 266     ciType*   pop_value() {
 267       ciType* t = type_at_tos();
 268       pop();
 269       return t;
 270     }
 271 
 272     // Convenience operations.
 273     bool      is_reference(ciType* type) const {
 274       return type == null_type() || !type->is_primitive_type();
 275     }
 276     bool      is_int(ciType* type) const {
 277       return type->basic_type() == T_INT;
 278     }
 279     bool      is_long(ciType* type) const {
 280       return type->basic_type() == T_LONG;
 281     }
 282     bool      is_float(ciType* type) const {
 283       return type->basic_type() == T_FLOAT;
 284     }
 285     bool      is_double(ciType* type) const {
 286       return type->basic_type() == T_DOUBLE;
 287     }
 288 
 289     void store_to_local(int lnum) {
 290       _def_locals.add((uint) lnum);
 291     }
 292 
 293     void      push_translate(ciType* type);
 294 
 295     void      push_int() {
 296       push(ciType::make(T_INT));
 297     }
 298     void      pop_int() {
 299       assert(is_int(type_at_tos()), "must be integer");
 300       pop();
 301     }
 302     void      check_int(Cell c) {
 303       assert(is_int(type_at(c)), "must be integer");
 304     }
 305     void      push_double() {
 306       push(ciType::make(T_DOUBLE));
 307       push(double2_type());
 308     }
 309     void      pop_double() {
 310       assert(type_at_tos() == double2_type(), "must be 2nd half");
 311       pop();
 312       assert(is_double(type_at_tos()), "must be double");
 313       pop();
 314     }
 315     void      push_float() {
 316       push(ciType::make(T_FLOAT));
 317     }
 318     void      pop_float() {
 319       assert(is_float(type_at_tos()), "must be float");
 320       pop();
 321     }
 322     void      push_long() {
 323       push(ciType::make(T_LONG));
 324       push(long2_type());
 325     }
 326     void      pop_long() {
 327       assert(type_at_tos() == long2_type(), "must be 2nd half");
 328       pop();
 329       assert(is_long(type_at_tos()), "must be long");
 330       pop();
 331     }
 332     void      push_object(ciKlass* klass) {
 333       push(klass);
 334     }
 335     void      pop_object() {
 336       assert(is_reference(type_at_tos()), "must be reference type");
 337       pop();
 338     }
 339     void      pop_array() {
 340       assert(type_at_tos() == null_type() ||
 341              type_at_tos()->is_array_klass(), "must be array type");
 342       pop();
 343     }
 344     // pop_valueOrobjArray and pop_typeArray narrow the tos to ciObjArrayKlass,
 345     // ciValueArrayKlass or ciTypeArrayKlass (resp.). In the rare case that an explicit
 346     // null is popped from the stack, we return NULL.  Caller beware.
 347     ciArrayKlass* pop_objOrValueArray() {
 348       ciType* array = pop_value();
 349       if (array == null_type())  return NULL;
 350       // Value type arrays may contain oop or flattened representation
 351       assert(array->is_obj_array_klass() || (ValueArrayFlatten && array->is_value_array_klass()),
 352              "must be value or object array type");
 353       return array->as_array_klass();
 354     }
 355     ciTypeArrayKlass* pop_typeArray() {
 356       ciType* array = pop_value();
 357       if (array == null_type())  return NULL;
 358       assert(array->is_type_array_klass(), "must be prim array type");
 359       return array->as_type_array_klass();
 360     }
 361     void      push_null() {
 362       push(null_type());
 363     }
 364     void      do_null_assert(ciKlass* unloaded_klass);
 365 
 366     // Helper convenience routines.
 367     void do_aload(ciBytecodeStream* str);
 368     void do_checkcast(ciBytecodeStream* str);
 369     void do_getfield(ciBytecodeStream* str);
 370     void do_getstatic(ciBytecodeStream* str);
 371     void do_invoke(ciBytecodeStream* str, bool has_receiver);
 372     void do_jsr(ciBytecodeStream* str);
 373     void do_ldc(ciBytecodeStream* str);
 374     void do_multianewarray(ciBytecodeStream* str);
 375     void do_new(ciBytecodeStream* str);
 376     void do_vnew(ciBytecodeStream* str);
 377     void do_newarray(ciBytecodeStream* str);
 378     void do_putfield(ciBytecodeStream* str);
 379     void do_putstatic(ciBytecodeStream* str);
 380     void do_ret(ciBytecodeStream* str);
 381     void do_vunbox(ciBytecodeStream* str);
 382     void do_vbox(ciBytecodeStream* str);
 383 
 384     void overwrite_local_double_long(int index) {
 385       // Invalidate the previous local if it contains first half of
 386       // a double or long value since it's seconf half is being overwritten.
 387       int prev_index = index - 1;
 388       if (prev_index >= 0 &&
 389           (is_double(type_at(local(prev_index))) ||
 390            is_long(type_at(local(prev_index))))) {
 391         set_type_at(local(prev_index), bottom_type());
 392       }
 393     }
 394 
 395     void load_local_object(int index) {
 396       ciType* type = type_at(local(index));
 397       assert(is_reference(type), "must be reference type");
 398       push(type);
 399     }
 400     void store_local_object(int index) {
 401       ciType* type = pop_value();
 402       assert(is_reference(type) || type->is_return_address(),
 403              "must be reference type or return address");
 404       overwrite_local_double_long(index);
 405       set_type_at(local(index), type);
 406       store_to_local(index);
 407     }
 408 
 409     void load_local_double(int index) {
 410       ciType* type = type_at(local(index));
 411       ciType* type2 = type_at(local(index+1));
 412       assert(is_double(type), "must be double type");
 413       assert(type2 == double2_type(), "must be 2nd half");
 414       push(type);
 415       push(double2_type());
 416     }
 417     void store_local_double(int index) {
 418       ciType* type2 = pop_value();
 419       ciType* type = pop_value();
 420       assert(is_double(type), "must be double");
 421       assert(type2 == double2_type(), "must be 2nd half");
 422       overwrite_local_double_long(index);
 423       set_type_at(local(index), type);
 424       set_type_at(local(index+1), type2);
 425       store_to_local(index);
 426       store_to_local(index+1);
 427     }
 428 
 429     void load_local_float(int index) {
 430       ciType* type = type_at(local(index));
 431       assert(is_float(type), "must be float type");
 432       push(type);
 433     }
 434     void store_local_float(int index) {
 435       ciType* type = pop_value();
 436       assert(is_float(type), "must be float type");
 437       overwrite_local_double_long(index);
 438       set_type_at(local(index), type);
 439       store_to_local(index);
 440     }
 441 
 442     void load_local_int(int index) {
 443       ciType* type = type_at(local(index));
 444       assert(is_int(type), "must be int type");
 445       push(type);
 446     }
 447     void store_local_int(int index) {
 448       ciType* type = pop_value();
 449       assert(is_int(type), "must be int type");
 450       overwrite_local_double_long(index);
 451       set_type_at(local(index), type);
 452       store_to_local(index);
 453     }
 454 
 455     void load_local_long(int index) {
 456       ciType* type = type_at(local(index));
 457       ciType* type2 = type_at(local(index+1));
 458       assert(is_long(type), "must be long type");
 459       assert(type2 == long2_type(), "must be 2nd half");
 460       push(type);
 461       push(long2_type());
 462     }
 463     void store_local_long(int index) {
 464       ciType* type2 = pop_value();
 465       ciType* type = pop_value();
 466       assert(is_long(type), "must be long");
 467       assert(type2 == long2_type(), "must be 2nd half");
 468       overwrite_local_double_long(index);
 469       set_type_at(local(index), type);
 470       set_type_at(local(index+1), type2);
 471       store_to_local(index);
 472       store_to_local(index+1);
 473     }
 474 
 475     // Stop interpretation of this path with a trap.
 476     void trap(ciBytecodeStream* str, ciKlass* klass, int index);
 477 
 478   public:
 479     StateVector(ciTypeFlow* outer);
 480 
 481     // Copy our value into some other StateVector
 482     void copy_into(StateVector* copy) const;
 483 
 484     // Meets this StateVector with another, destructively modifying this
 485     // one.  Returns true if any modification takes place.
 486     bool meet(const StateVector* incoming);
 487 
 488     // Ditto, except that the incoming state is coming from an exception.
 489     bool meet_exception(ciInstanceKlass* exc, const StateVector* incoming);
 490 
 491     // Apply the effect of one bytecode to this StateVector
 492     bool apply_one_bytecode(ciBytecodeStream* stream);
 493 
 494     // What is the bci of the trap?
 495     int  trap_bci() { return _trap_bci; }
 496 
 497     // What is the index associated with the trap?
 498     int  trap_index() { return _trap_index; }
 499 
 500     void print_cell_on(outputStream* st, Cell c) const PRODUCT_RETURN;
 501     void print_on(outputStream* st) const              PRODUCT_RETURN;
 502   };
 503 
 504   // Parameter for "find_block" calls:
 505   // Describes the difference between a public and backedge copy.
 506   enum CreateOption {
 507     create_public_copy,
 508     create_backedge_copy,
 509     no_create
 510   };
 511 
 512   // Successor iterator
 513   class SuccIter : public StackObj {
 514   private:
 515     Block* _pred;
 516     int    _index;
 517     Block* _succ;
 518   public:
 519     SuccIter()                        : _pred(NULL), _index(-1), _succ(NULL) {}
 520     SuccIter(Block* pred)             : _pred(pred), _index(-1), _succ(NULL) { next(); }
 521     int    index()     { return _index; }
 522     Block* pred()      { return _pred; }           // Return predecessor
 523     bool   done()      { return _index < 0; }      // Finished?
 524     Block* succ()      { return _succ; }           // Return current successor
 525     void   next();                                 // Advance
 526     void   set_succ(Block* succ);                  // Update current successor
 527     bool   is_normal_ctrl() { return index() < _pred->successors()->length(); }
 528   };
 529 
 530   // A basic block
 531   class Block : public ResourceObj {
 532   private:
 533     ciBlock*                          _ciblock;
 534     GrowableArray<Block*>*           _exceptions;
 535     GrowableArray<ciInstanceKlass*>* _exc_klasses;
 536     GrowableArray<Block*>*           _successors;
 537     GrowableArray<Block*>*           _predecessors;
 538     StateVector*                     _state;
 539     JsrSet*                          _jsrs;
 540 
 541     int                              _trap_bci;
 542     int                              _trap_index;
 543 
 544     // pre_order, assigned at first visit. Used as block ID and "visited" tag
 545     int                              _pre_order;
 546 
 547     // A post-order, used to compute the reverse post order (RPO) provided to the client
 548     int                              _post_order;  // used to compute rpo
 549 
 550     // Has this block been cloned for a loop backedge?
 551     bool                             _backedge_copy;
 552 
 553     // This block is entry to irreducible loop.
 554     bool                             _irreducible_entry;
 555 
 556     // This block has monitor entry point.
 557     bool                             _has_monitorenter;
 558 
 559     // A pointer used for our internal work list
 560     bool                             _on_work_list;      // on the work list
 561     Block*                           _next;
 562     Block*                           _rpo_next;          // Reverse post order list
 563 
 564     // Loop info
 565     Loop*                            _loop;              // nearest loop
 566 
 567     ciBlock*     ciblock() const     { return _ciblock; }
 568     StateVector* state() const     { return _state; }
 569 
 570     // Compute the exceptional successors and types for this Block.
 571     void compute_exceptions();
 572 
 573   public:
 574     // constructors
 575     Block(ciTypeFlow* outer, ciBlock* ciblk, JsrSet* jsrs);
 576 
 577     void set_trap(int trap_bci, int trap_index) {
 578       _trap_bci = trap_bci;
 579       _trap_index = trap_index;
 580       assert(has_trap(), "");
 581     }
 582     bool has_trap()   const  { return _trap_bci != -1; }
 583     int  trap_bci()   const  { assert(has_trap(), ""); return _trap_bci; }
 584     int  trap_index() const  { assert(has_trap(), ""); return _trap_index; }
 585 
 586     // accessors
 587     ciTypeFlow* outer() const { return state()->outer(); }
 588     int start() const         { return _ciblock->start_bci(); }
 589     int limit() const         { return _ciblock->limit_bci(); }
 590     int control() const       { return _ciblock->control_bci(); }
 591     JsrSet* jsrs() const      { return _jsrs; }
 592 
 593     bool    is_backedge_copy() const       { return _backedge_copy; }
 594     void   set_backedge_copy(bool z);
 595     int        backedge_copy_count() const { return outer()->backedge_copy_count(ciblock()->index(), _jsrs); }
 596 
 597     // access to entry state
 598     int     stack_size() const         { return _state->stack_size(); }
 599     int     monitor_count() const      { return _state->monitor_count(); }
 600     ciType* local_type_at(int i) const { return _state->local_type_at(i); }
 601     ciType* stack_type_at(int i) const { return _state->stack_type_at(i); }
 602 
 603     // Data flow on locals
 604     bool is_invariant_local(uint v) const {
 605       assert(is_loop_head(), "only loop heads");
 606       // Find outermost loop with same loop head
 607       Loop* lp = loop();
 608       while (lp->parent() != NULL) {
 609         if (lp->parent()->head() != lp->head()) break;
 610         lp = lp->parent();
 611       }
 612       return !lp->def_locals()->test(v);
 613     }
 614     LocalSet* def_locals() { return _state->def_locals(); }
 615     const LocalSet* def_locals() const { return _state->def_locals(); }
 616 
 617     // Get the successors for this Block.
 618     GrowableArray<Block*>* successors(ciBytecodeStream* str,
 619                                       StateVector* state,
 620                                       JsrSet* jsrs);
 621     GrowableArray<Block*>* successors() {
 622       assert(_successors != NULL, "must be filled in");
 623       return _successors;
 624     }
 625 
 626     // Predecessors of this block (including exception edges)
 627     GrowableArray<Block*>* predecessors() {
 628       assert(_predecessors != NULL, "must be filled in");
 629       return _predecessors;
 630     }
 631 
 632     // Get the exceptional successors for this Block.
 633     GrowableArray<Block*>* exceptions() {
 634       if (_exceptions == NULL) {
 635         compute_exceptions();
 636       }
 637       return _exceptions;
 638     }
 639 
 640     // Get the exception klasses corresponding to the
 641     // exceptional successors for this Block.
 642     GrowableArray<ciInstanceKlass*>* exc_klasses() {
 643       if (_exc_klasses == NULL) {
 644         compute_exceptions();
 645       }
 646       return _exc_klasses;
 647     }
 648 
 649     // Is this Block compatible with a given JsrSet?
 650     bool is_compatible_with(JsrSet* other) {
 651       return _jsrs->is_compatible_with(other);
 652     }
 653 
 654     // Copy the value of our state vector into another.
 655     void copy_state_into(StateVector* copy) const {
 656       _state->copy_into(copy);
 657     }
 658 
 659     // Copy the value of our JsrSet into another
 660     void copy_jsrs_into(JsrSet* copy) const {
 661       _jsrs->copy_into(copy);
 662     }
 663 
 664     // Meets the start state of this block with another state, destructively
 665     // modifying this one.  Returns true if any modification takes place.
 666     bool meet(const StateVector* incoming) {
 667       return state()->meet(incoming);
 668     }
 669 
 670     // Ditto, except that the incoming state is coming from an
 671     // exception path.  This means the stack is replaced by the
 672     // appropriate exception type.
 673     bool meet_exception(ciInstanceKlass* exc, const StateVector* incoming) {
 674       return state()->meet_exception(exc, incoming);
 675     }
 676 
 677     // Work list manipulation
 678     void   set_next(Block* block) { _next = block; }
 679     Block* next() const           { return _next; }
 680 
 681     void   set_on_work_list(bool c) { _on_work_list = c; }
 682     bool   is_on_work_list() const  { return _on_work_list; }
 683 
 684     bool   has_pre_order() const  { return _pre_order >= 0; }
 685     void   set_pre_order(int po)  { assert(!has_pre_order(), ""); _pre_order = po; }
 686     int    pre_order() const      { assert(has_pre_order(), ""); return _pre_order; }
 687     void   set_next_pre_order()   { set_pre_order(outer()->inc_next_pre_order()); }
 688     bool   is_start() const       { return _pre_order == outer()->start_block_num(); }
 689 
 690     // Reverse post order
 691     void   df_init();
 692     bool   has_post_order() const { return _post_order >= 0; }
 693     void   set_post_order(int po) { assert(!has_post_order() && po >= 0, ""); _post_order = po; }
 694     void   reset_post_order(int o){ _post_order = o; }
 695     int    post_order() const     { assert(has_post_order(), ""); return _post_order; }
 696 
 697     bool   has_rpo() const        { return has_post_order() && outer()->have_block_count(); }
 698     int    rpo() const            { assert(has_rpo(), ""); return outer()->block_count() - post_order() - 1; }
 699     void   set_rpo_next(Block* b) { _rpo_next = b; }
 700     Block* rpo_next()             { return _rpo_next; }
 701 
 702     // Loops
 703     Loop*  loop() const                  { return _loop; }
 704     void   set_loop(Loop* lp)            { _loop = lp; }
 705     bool   is_loop_head() const          { return _loop && _loop->head() == this; }
 706     void   set_irreducible_entry(bool c) { _irreducible_entry = c; }
 707     bool   is_irreducible_entry() const  { return _irreducible_entry; }
 708     void   set_has_monitorenter()        { _has_monitorenter = true; }
 709     bool   has_monitorenter() const      { return _has_monitorenter; }
 710     bool   is_visited() const            { return has_pre_order(); }
 711     bool   is_post_visited() const       { return has_post_order(); }
 712     bool   is_clonable_exit(Loop* lp);
 713     Block* looping_succ(Loop* lp);       // Successor inside of loop
 714     bool   is_single_entry_loop_head() const {
 715       if (!is_loop_head()) return false;
 716       for (Loop* lp = loop(); lp != NULL && lp->head() == this; lp = lp->parent())
 717         if (lp->is_irreducible()) return false;
 718       return true;
 719     }
 720 
 721     void   print_value_on(outputStream* st) const PRODUCT_RETURN;
 722     void   print_on(outputStream* st) const       PRODUCT_RETURN;
 723   };
 724 
 725   // Loop
 726   class Loop : public ResourceObj {
 727   private:
 728     Loop* _parent;
 729     Loop* _sibling;  // List of siblings, null terminated
 730     Loop* _child;    // Head of child list threaded thru sibling pointer
 731     Block* _head;    // Head of loop
 732     Block* _tail;    // Tail of loop
 733     bool   _irreducible;
 734     LocalSet _def_locals;
 735 
 736   public:
 737     Loop(Block* head, Block* tail) :
 738       _head(head),   _tail(tail),
 739       _parent(NULL), _sibling(NULL), _child(NULL),
 740       _irreducible(false), _def_locals() {}
 741 
 742     Loop* parent()  const { return _parent; }
 743     Loop* sibling() const { return _sibling; }
 744     Loop* child()   const { return _child; }
 745     Block* head()   const { return _head; }
 746     Block* tail()   const { return _tail; }
 747     void set_parent(Loop* p)  { _parent = p; }
 748     void set_sibling(Loop* s) { _sibling = s; }
 749     void set_child(Loop* c)   { _child = c; }
 750     void set_head(Block* hd)  { _head = hd; }
 751     void set_tail(Block* tl)  { _tail = tl; }
 752 
 753     int depth() const;              // nesting depth
 754 
 755     // Returns true if lp is a nested loop or us.
 756     bool contains(Loop* lp) const;
 757     bool contains(Block* blk) const { return contains(blk->loop()); }
 758 
 759     // Data flow on locals
 760     LocalSet* def_locals() { return &_def_locals; }
 761     const LocalSet* def_locals() const { return &_def_locals; }
 762 
 763     // Merge the branch lp into this branch, sorting on the loop head
 764     // pre_orders. Returns the new branch.
 765     Loop* sorted_merge(Loop* lp);
 766 
 767     // Mark non-single entry to loop
 768     void set_irreducible(Block* entry) {
 769       _irreducible = true;
 770       entry->set_irreducible_entry(true);
 771     }
 772     bool is_irreducible() const { return _irreducible; }
 773 
 774     bool is_root() const { return _tail->pre_order() == max_jint; }
 775 
 776     void print(outputStream* st = tty, int indent = 0) const PRODUCT_RETURN;
 777   };
 778 
 779   // Postorder iteration over the loop tree.
 780   class PostorderLoops : public StackObj {
 781   private:
 782     Loop* _root;
 783     Loop* _current;
 784   public:
 785     PostorderLoops(Loop* root) : _root(root), _current(root) {
 786       while (_current->child() != NULL) {
 787         _current = _current->child();
 788       }
 789     }
 790     bool done() { return _current == NULL; }  // Finished iterating?
 791     void next();                            // Advance to next loop
 792     Loop* current() { return _current; }      // Return current loop.
 793   };
 794 
 795   // Preorder iteration over the loop tree.
 796   class PreorderLoops : public StackObj {
 797   private:
 798     Loop* _root;
 799     Loop* _current;
 800   public:
 801     PreorderLoops(Loop* root) : _root(root), _current(root) {}
 802     bool done() { return _current == NULL; }  // Finished iterating?
 803     void next();                            // Advance to next loop
 804     Loop* current() { return _current; }      // Return current loop.
 805   };
 806 
 807   // Standard indexes of successors, for various bytecodes.
 808   enum {
 809     FALL_THROUGH   = 0,  // normal control
 810     IF_NOT_TAKEN   = 0,  // the not-taken branch of an if (i.e., fall-through)
 811     IF_TAKEN       = 1,  // the taken branch of an if
 812     GOTO_TARGET    = 0,  // unique successor for goto, jsr, or ret
 813     SWITCH_DEFAULT = 0,  // default branch of a switch
 814     SWITCH_CASES   = 1   // first index for any non-default switch branches
 815     // Unlike in other blocks, the successors of a switch are listed uniquely.
 816   };
 817 
 818 private:
 819   // A mapping from pre_order to Blocks.  This array is created
 820   // only at the end of the flow.
 821   Block** _block_map;
 822 
 823   // For each ciBlock index, a list of Blocks which share this ciBlock.
 824   GrowableArray<Block*>** _idx_to_blocklist;
 825   // count of ciBlocks
 826   int _ciblock_count;
 827 
 828   // Tells if a given instruction is able to generate an exception edge.
 829   bool can_trap(ciBytecodeStream& str);
 830 
 831   // Clone the loop heads. Returns true if any cloning occurred.
 832   bool clone_loop_heads(Loop* lp, StateVector* temp_vector, JsrSet* temp_set);
 833 
 834   // Clone lp's head and replace tail's successors with clone.
 835   Block* clone_loop_head(Loop* lp, StateVector* temp_vector, JsrSet* temp_set);
 836 
 837 public:
 838   // Return the block beginning at bci which has a JsrSet compatible
 839   // with jsrs.
 840   Block* block_at(int bci, JsrSet* set, CreateOption option = create_public_copy);
 841 
 842   // block factory
 843   Block* get_block_for(int ciBlockIndex, JsrSet* jsrs, CreateOption option = create_public_copy);
 844 
 845   // How many of the blocks have the backedge_copy bit set?
 846   int backedge_copy_count(int ciBlockIndex, JsrSet* jsrs) const;
 847 
 848   // Return an existing block containing bci which has a JsrSet compatible
 849   // with jsrs, or NULL if there is none.
 850   Block* existing_block_at(int bci, JsrSet* set) { return block_at(bci, set, no_create); }
 851 
 852   // Tell whether the flow analysis has encountered an error of some sort.
 853   bool failing() { return env()->failing() || _failure_reason != NULL; }
 854 
 855   // Reason this compilation is failing, such as "too many basic blocks".
 856   const char* failure_reason() { return _failure_reason; }
 857 
 858   // Note a failure.
 859   void record_failure(const char* reason);
 860 
 861   // Return the block of a given pre-order number.
 862   int have_block_count() const      { return _block_map != NULL; }
 863   int block_count() const           { assert(have_block_count(), "");
 864                                       return _next_pre_order; }
 865   Block* pre_order_at(int po) const { assert(0 <= po && po < block_count(), "out of bounds");
 866                                       return _block_map[po]; }
 867   Block* start_block() const        { return pre_order_at(start_block_num()); }
 868   int start_block_num() const       { return 0; }
 869   Block* rpo_at(int rpo) const      { assert(0 <= rpo && rpo < block_count(), "out of bounds");
 870                                       return _block_map[rpo]; }
 871   int next_pre_order()              { return _next_pre_order; }
 872   int inc_next_pre_order()          { return _next_pre_order++; }
 873 
 874 private:
 875   // A work list used during flow analysis.
 876   Block* _work_list;
 877 
 878   // List of blocks in reverse post order
 879   Block* _rpo_list;
 880 
 881   // Next Block::_pre_order.  After mapping, doubles as block_count.
 882   int _next_pre_order;
 883 
 884   // Are there more blocks on the work list?
 885   bool work_list_empty() { return _work_list == NULL; }
 886 
 887   // Get the next basic block from our work list.
 888   Block* work_list_next();
 889 
 890   // Add a basic block to our work list.
 891   void add_to_work_list(Block* block);
 892 
 893   // Prepend a basic block to rpo list.
 894   void prepend_to_rpo_list(Block* blk) {
 895     blk->set_rpo_next(_rpo_list);
 896     _rpo_list = blk;
 897   }
 898 
 899   // Root of the loop tree
 900   Loop* _loop_tree_root;
 901 
 902   // State used for make_jsr_record
 903   int _jsr_count;
 904   GrowableArray<JsrRecord*>* _jsr_records;
 905 
 906 public:
 907   // Make a JsrRecord for a given (entry, return) pair, if such a record
 908   // does not already exist.
 909   JsrRecord* make_jsr_record(int entry_address, int return_address);
 910 
 911   void  set_loop_tree_root(Loop* ltr) { _loop_tree_root = ltr; }
 912   Loop* loop_tree_root()              { return _loop_tree_root; }
 913 
 914 private:
 915   // Get the initial state for start_bci:
 916   const StateVector* get_start_state();
 917 
 918   // Merge the current state into all exceptional successors at the
 919   // current point in the code.
 920   void flow_exceptions(GrowableArray<Block*>* exceptions,
 921                        GrowableArray<ciInstanceKlass*>* exc_klasses,
 922                        StateVector* state);
 923 
 924   // Merge the current state into all successors at the current point
 925   // in the code.
 926   void flow_successors(GrowableArray<Block*>* successors,
 927                        StateVector* state);
 928 
 929   // Interpret the effects of the bytecodes on the incoming state
 930   // vector of a basic block.  Push the changed state to succeeding
 931   // basic blocks.
 932   void flow_block(Block* block,
 933                   StateVector* scratch_state,
 934                   JsrSet* scratch_jsrs);
 935 
 936   // Perform the type flow analysis, creating and cloning Blocks as
 937   // necessary.
 938   void flow_types();
 939 
 940   // Perform the depth first type flow analysis. Helper for flow_types.
 941   void df_flow_types(Block* start,
 942                      bool do_flow,
 943                      StateVector* temp_vector,
 944                      JsrSet* temp_set);
 945 
 946   // Incrementally build loop tree.
 947   void build_loop_tree(Block* blk);
 948 
 949   // Create the block map, which indexes blocks in pre_order.
 950   void map_blocks();
 951 
 952 public:
 953   // Perform type inference flow analysis.
 954   void do_flow();
 955 
 956   // Determine if bci is dominated by dom_bci
 957   bool is_dominated_by(int bci, int dom_bci);
 958 
 959   void print_on(outputStream* st) const PRODUCT_RETURN;
 960 
 961   void rpo_print_on(outputStream* st) const PRODUCT_RETURN;
 962 };
 963 
 964 #endif // SHARE_VM_CI_CITYPEFLOW_HPP
--- EOF ---