1 /*
   2  * Copyright (c) 2005, 2021, 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 "classfile/vmIntrinsics.hpp"
  27 #include "ci/bcEscapeAnalyzer.hpp"
  28 #include "ci/ciConstant.hpp"
  29 #include "ci/ciField.hpp"
  30 #include "ci/ciMethodBlocks.hpp"
  31 #include "ci/ciStreams.hpp"
  32 #include "compiler/compiler_globals.hpp"
  33 #include "interpreter/bytecode.hpp"
  34 #include "oops/oop.inline.hpp"
  35 #include "utilities/align.hpp"
  36 #include "utilities/bitMap.inline.hpp"
  37 #include "utilities/copy.hpp"
  38 
  39 #ifndef PRODUCT
  40   #define TRACE_BCEA(level, code)                                            \
  41     if (EstimateArgEscape && BCEATraceLevel >= level) {                        \
  42       code;                                                                  \
  43     }
  44 #else
  45   #define TRACE_BCEA(level, code)
  46 #endif
  47 
  48 // Maintain a map of which arguments a local variable or
  49 // stack slot may contain.  In addition to tracking
  50 // arguments, it tracks two special values, "allocated"
  51 // which represents any object allocated in the current
  52 // method, and "unknown" which is any other object.
  53 // Up to 30 arguments are handled, with the last one
  54 // representing summary information for any extra arguments
  55 class BCEscapeAnalyzer::ArgumentMap {
  56   uint  _bits;
  57   enum {MAXBIT = 29,
  58         ALLOCATED = 1,
  59         UNKNOWN = 2};
  60 
  61   uint int_to_bit(uint e) const {
  62     if (e > MAXBIT)
  63       e = MAXBIT;
  64     return (1 << (e + 2));
  65   }
  66 
  67 public:
  68   ArgumentMap()                         { _bits = 0;}
  69   void set_bits(uint bits)              { _bits = bits;}
  70   uint get_bits() const                 { return _bits;}
  71   void clear()                          { _bits = 0;}
  72   void set_all()                        { _bits = ~0u; }
  73   bool is_empty() const                 { return _bits == 0; }
  74   bool contains(uint var) const         { return (_bits & int_to_bit(var)) != 0; }
  75   bool is_singleton(uint var) const     { return (_bits == int_to_bit(var)); }
  76   bool contains_unknown() const         { return (_bits & UNKNOWN) != 0; }
  77   bool contains_allocated() const       { return (_bits & ALLOCATED) != 0; }
  78   bool contains_vars() const            { return (_bits & (((1 << MAXBIT) -1) << 2)) != 0; }
  79   void set(uint var)                    { _bits = int_to_bit(var); }
  80   void add(uint var)                    { _bits |= int_to_bit(var); }
  81   void add_unknown()                    { _bits = UNKNOWN; }
  82   void add_allocated()                  { _bits = ALLOCATED; }
  83   void set_union(const ArgumentMap &am)     { _bits |= am._bits; }
  84   void set_difference(const ArgumentMap &am) { _bits &=  ~am._bits; }
  85   bool operator==(const ArgumentMap &am) { return _bits == am._bits; }
  86   bool operator!=(const ArgumentMap &am) { return _bits != am._bits; }
  87 };
  88 
  89 class BCEscapeAnalyzer::StateInfo {
  90 public:
  91   ArgumentMap *_vars;
  92   ArgumentMap *_stack;
  93   int _stack_height;
  94   int _max_stack;
  95   bool _initialized;
  96   ArgumentMap empty_map;
  97 
  98   StateInfo() {
  99     empty_map.clear();
 100   }
 101 
 102   ArgumentMap raw_pop()  { guarantee(_stack_height > 0, "stack underflow"); return _stack[--_stack_height]; }
 103   ArgumentMap  apop()    { return raw_pop(); }
 104   void spop()            { raw_pop(); }
 105   void lpop()            { spop(); spop(); }
 106   void raw_push(ArgumentMap i)   { guarantee(_stack_height < _max_stack, "stack overflow"); _stack[_stack_height++] = i; }
 107   void apush(ArgumentMap i)      { raw_push(i); }
 108   void spush()           { raw_push(empty_map); }
 109   void lpush()           { spush(); spush(); }
 110 
 111 };
 112 
 113 void BCEscapeAnalyzer::set_returned(ArgumentMap vars) {
 114   for (int i = 0; i < _arg_size; i++) {
 115     if (vars.contains(i))
 116       _arg_returned.set(i);
 117   }
 118   _return_local = _return_local && !(vars.contains_unknown() || vars.contains_allocated());
 119   _return_allocated = _return_allocated && vars.contains_allocated() && !(vars.contains_unknown() || vars.contains_vars());
 120 }
 121 
 122 // return true if any element of vars is an argument
 123 bool BCEscapeAnalyzer::is_argument(ArgumentMap vars) {
 124   for (int i = 0; i < _arg_size; i++) {
 125     if (vars.contains(i))
 126       return true;
 127   }
 128   return false;
 129 }
 130 
 131 // return true if any element of vars is an arg_stack argument
 132 bool BCEscapeAnalyzer::is_arg_stack(ArgumentMap vars){
 133   if (_conservative)
 134     return true;
 135   for (int i = 0; i < _arg_size; i++) {
 136     if (vars.contains(i) && _arg_stack.test(i))
 137       return true;
 138   }
 139   return false;
 140 }
 141 
 142 // return true if all argument elements of vars are returned
 143 bool BCEscapeAnalyzer::returns_all(ArgumentMap vars) {
 144   for (int i = 0; i < _arg_size; i++) {
 145     if (vars.contains(i) && !_arg_returned.test(i)) {
 146       return false;
 147     }
 148   }
 149   return true;
 150 }
 151 
 152 void BCEscapeAnalyzer::clear_bits(ArgumentMap vars, VectorSet &bm) {
 153   for (int i = 0; i < _arg_size; i++) {
 154     if (vars.contains(i)) {
 155       bm.remove(i);
 156     }
 157   }
 158 }
 159 
 160 void BCEscapeAnalyzer::set_method_escape(ArgumentMap vars) {
 161   clear_bits(vars, _arg_local);
 162   if (vars.contains_allocated()) {
 163     _allocated_escapes = true;
 164   }
 165 }
 166 
 167 void BCEscapeAnalyzer::set_global_escape(ArgumentMap vars, bool merge) {
 168   clear_bits(vars, _arg_local);
 169   clear_bits(vars, _arg_stack);
 170   if (vars.contains_allocated())
 171     _allocated_escapes = true;
 172 
 173   if (merge && !vars.is_empty()) {
 174     // Merge new state into already processed block.
 175     // New state is not taken into account and
 176     // it may invalidate set_returned() result.
 177     if (vars.contains_unknown() || vars.contains_allocated()) {
 178       _return_local = false;
 179     }
 180     if (vars.contains_unknown() || vars.contains_vars()) {
 181       _return_allocated = false;
 182     }
 183     if (_return_local && vars.contains_vars() && !returns_all(vars)) {
 184       // Return result should be invalidated if args in new
 185       // state are not recorded in return state.
 186       _return_local = false;
 187     }
 188   }
 189 }
 190 
 191 void BCEscapeAnalyzer::set_modified(ArgumentMap vars, int offs, int size) {
 192 
 193   for (int i = 0; i < _arg_size; i++) {
 194     if (vars.contains(i)) {
 195       set_arg_modified(i, offs, size);
 196     }
 197   }
 198   if (vars.contains_unknown())
 199     _unknown_modified = true;
 200 }
 201 
 202 bool BCEscapeAnalyzer::is_recursive_call(ciMethod* callee) {
 203   for (BCEscapeAnalyzer* scope = this; scope != NULL; scope = scope->_parent) {
 204     if (scope->method() == callee) {
 205       return true;
 206     }
 207   }
 208   return false;
 209 }
 210 
 211 bool BCEscapeAnalyzer::is_arg_modified(int arg, int offset, int size_in_bytes) {
 212   if (offset == OFFSET_ANY)
 213     return _arg_modified[arg] != 0;
 214   assert(arg >= 0 && arg < _arg_size, "must be an argument.");
 215   bool modified = false;
 216   int l = offset / HeapWordSize;
 217   int h = align_up(offset + size_in_bytes, HeapWordSize) / HeapWordSize;
 218   if (l > ARG_OFFSET_MAX)
 219     l = ARG_OFFSET_MAX;
 220   if (h > ARG_OFFSET_MAX+1)
 221     h = ARG_OFFSET_MAX + 1;
 222   for (int i = l; i < h; i++) {
 223     modified = modified || (_arg_modified[arg] & (1 << i)) != 0;
 224   }
 225   return modified;
 226 }
 227 
 228 void BCEscapeAnalyzer::set_arg_modified(int arg, int offset, int size_in_bytes) {
 229   if (offset == OFFSET_ANY) {
 230     _arg_modified[arg] =  (uint) -1;
 231     return;
 232   }
 233   assert(arg >= 0 && arg < _arg_size, "must be an argument.");
 234   int l = offset / HeapWordSize;
 235   int h = align_up(offset + size_in_bytes, HeapWordSize) / HeapWordSize;
 236   if (l > ARG_OFFSET_MAX)
 237     l = ARG_OFFSET_MAX;
 238   if (h > ARG_OFFSET_MAX+1)
 239     h = ARG_OFFSET_MAX + 1;
 240   for (int i = l; i < h; i++) {
 241     _arg_modified[arg] |= (1 << i);
 242   }
 243 }
 244 
 245 void BCEscapeAnalyzer::invoke(StateInfo &state, Bytecodes::Code code, ciMethod* target, ciKlass* holder) {
 246   int i;
 247 
 248   // retrieve information about the callee
 249   ciInstanceKlass* klass = target->holder();
 250   ciInstanceKlass* calling_klass = method()->holder();
 251   ciInstanceKlass* callee_holder = ciEnv::get_instance_klass_for_declared_method_holder(holder);
 252   ciInstanceKlass* actual_recv = callee_holder;
 253 
 254   // Some methods are obviously bindable without any type checks so
 255   // convert them directly to an invokespecial or invokestatic.
 256   if (target->is_loaded() && !target->is_abstract() && target->can_be_statically_bound()) {
 257     switch (code) {
 258     case Bytecodes::_invokevirtual:
 259       code = Bytecodes::_invokespecial;
 260       break;
 261     case Bytecodes::_invokehandle:
 262       code = target->is_static() ? Bytecodes::_invokestatic : Bytecodes::_invokespecial;
 263       break;
 264     default:
 265       break;
 266     }
 267   }
 268 
 269   // compute size of arguments
 270   int arg_size = target->invoke_arg_size(code);
 271   int arg_base = MAX2(state._stack_height - arg_size, 0);
 272 
 273   // direct recursive calls are skipped if they can be bound statically without introducing
 274   // dependencies and if parameters are passed at the same position as in the current method
 275   // other calls are skipped if there are no non-escaped arguments passed to them
 276   bool directly_recursive = (method() == target) &&
 277                (code != Bytecodes::_invokevirtual || target->is_final_method() || state._stack[arg_base] .is_empty());
 278 
 279   // check if analysis of callee can safely be skipped
 280   bool skip_callee = true;
 281   for (i = state._stack_height - 1; i >= arg_base && skip_callee; i--) {
 282     ArgumentMap arg = state._stack[i];
 283     skip_callee = !is_argument(arg) || !is_arg_stack(arg) || (directly_recursive && arg.is_singleton(i - arg_base));
 284   }
 285   // For now we conservatively skip invokedynamic.
 286   if (code == Bytecodes::_invokedynamic) {
 287     skip_callee = true;
 288   }
 289   if (skip_callee) {
 290     TRACE_BCEA(3, tty->print_cr("[EA] skipping method %s::%s", holder->name()->as_utf8(), target->name()->as_utf8()));
 291     for (i = 0; i < arg_size; i++) {
 292       set_method_escape(state.raw_pop());
 293     }
 294     _unknown_modified = true;  // assume the worst since we don't analyze the called method
 295     return;
 296   }
 297 
 298   // determine actual method (use CHA if necessary)
 299   ciMethod* inline_target = NULL;
 300   if (target->is_loaded() && klass->is_loaded()
 301       && (klass->is_initialized() || (klass->is_interface() && target->holder()->is_initialized()))) {
 302     if (code == Bytecodes::_invokestatic
 303         || code == Bytecodes::_invokespecial
 304         || (code == Bytecodes::_invokevirtual && target->is_final_method())) {
 305       inline_target = target;
 306     } else {
 307       inline_target = target->find_monomorphic_target(calling_klass, callee_holder, actual_recv);
 308     }
 309   }
 310 
 311   if (inline_target != NULL && !is_recursive_call(inline_target)) {
 312     // analyze callee
 313     BCEscapeAnalyzer analyzer(inline_target, this);
 314 
 315     // adjust escape state of actual parameters
 316     bool must_record_dependencies = false;
 317     for (i = arg_size - 1; i >= 0; i--) {
 318       ArgumentMap arg = state.raw_pop();
 319       // Check if callee arg is a caller arg or an allocated object
 320       bool allocated = arg.contains_allocated();
 321       if (!(is_argument(arg) || allocated))
 322         continue;
 323       for (int j = 0; j < _arg_size; j++) {
 324         if (arg.contains(j)) {
 325           _arg_modified[j] |= analyzer._arg_modified[i];
 326         }
 327       }
 328       if (!(is_arg_stack(arg) || allocated)) {
 329         // arguments have already been recognized as escaping
 330       } else if (analyzer.is_arg_stack(i) && !analyzer.is_arg_returned(i)) {
 331         set_method_escape(arg);
 332         must_record_dependencies = true;
 333       } else {
 334         set_global_escape(arg);
 335       }
 336     }
 337     _unknown_modified = _unknown_modified || analyzer.has_non_arg_side_affects();
 338 
 339     // record dependencies if at least one parameter retained stack-allocatable
 340     if (must_record_dependencies) {
 341       if (code == Bytecodes::_invokeinterface ||
 342           (code == Bytecodes::_invokevirtual && !target->is_final_method())) {
 343         _dependencies.append(actual_recv);
 344         _dependencies.append(inline_target);
 345         _dependencies.append(callee_holder);
 346         _dependencies.append(target);
 347         assert(callee_holder->is_interface() == (code == Bytecodes::_invokeinterface), "sanity");
 348       }
 349       _dependencies.appendAll(analyzer.dependencies());
 350     }
 351   } else {
 352     TRACE_BCEA(1, tty->print_cr("[EA] virtual method %s is not monomorphic.",
 353                                 target->name()->as_utf8()));
 354     // conservatively mark all actual parameters as escaping globally
 355     for (i = 0; i < arg_size; i++) {
 356       ArgumentMap arg = state.raw_pop();
 357       if (!is_argument(arg))
 358         continue;
 359       set_modified(arg, OFFSET_ANY, type2size[T_INT]*HeapWordSize);
 360       set_global_escape(arg);
 361     }
 362     _unknown_modified = true;  // assume the worst since we don't know the called method
 363   }
 364 }
 365 
 366 bool BCEscapeAnalyzer::contains(uint arg_set1, uint arg_set2) {
 367   return ((~arg_set1) | arg_set2) == 0;
 368 }
 369 
 370 
 371 void BCEscapeAnalyzer::iterate_one_block(ciBlock *blk, StateInfo &state, GrowableArray<ciBlock *> &successors) {
 372 
 373   blk->set_processed();
 374   ciBytecodeStream s(method());
 375   int limit_bci = blk->limit_bci();
 376   bool fall_through = false;
 377   ArgumentMap allocated_obj;
 378   allocated_obj.add_allocated();
 379   ArgumentMap unknown_obj;
 380   unknown_obj.add_unknown();
 381   ArgumentMap empty_map;
 382 
 383   s.reset_to_bci(blk->start_bci());
 384   while (s.next() != ciBytecodeStream::EOBC() && s.cur_bci() < limit_bci) {
 385     fall_through = true;
 386     switch (s.cur_bc()) {
 387       case Bytecodes::_nop:
 388         break;
 389       case Bytecodes::_aconst_null:
 390         state.apush(unknown_obj);
 391         break;
 392       case Bytecodes::_iconst_m1:
 393       case Bytecodes::_iconst_0:
 394       case Bytecodes::_iconst_1:
 395       case Bytecodes::_iconst_2:
 396       case Bytecodes::_iconst_3:
 397       case Bytecodes::_iconst_4:
 398       case Bytecodes::_iconst_5:
 399       case Bytecodes::_fconst_0:
 400       case Bytecodes::_fconst_1:
 401       case Bytecodes::_fconst_2:
 402       case Bytecodes::_bipush:
 403       case Bytecodes::_sipush:
 404         state.spush();
 405         break;
 406       case Bytecodes::_lconst_0:
 407       case Bytecodes::_lconst_1:
 408       case Bytecodes::_dconst_0:
 409       case Bytecodes::_dconst_1:
 410         state.lpush();
 411         break;
 412       case Bytecodes::_ldc:
 413       case Bytecodes::_ldc_w:
 414       case Bytecodes::_ldc2_w:
 415       {
 416         // Avoid calling get_constant() which will try to allocate
 417         // unloaded constant. We need only constant's type.
 418         int index = s.get_constant_pool_index();
 419         constantTag tag = s.get_constant_pool_tag(index);
 420         if (tag.is_long() || tag.is_double()) {
 421           // Only longs and doubles use 2 stack slots.
 422           state.lpush();
 423         } else if (tag.basic_type() == T_OBJECT) {
 424           state.apush(unknown_obj);
 425         } else {
 426           state.spush();
 427         }
 428         break;
 429       }
 430       case Bytecodes::_aload:
 431         state.apush(state._vars[s.get_index()]);
 432         break;
 433       case Bytecodes::_iload:
 434       case Bytecodes::_fload:
 435       case Bytecodes::_iload_0:
 436       case Bytecodes::_iload_1:
 437       case Bytecodes::_iload_2:
 438       case Bytecodes::_iload_3:
 439       case Bytecodes::_fload_0:
 440       case Bytecodes::_fload_1:
 441       case Bytecodes::_fload_2:
 442       case Bytecodes::_fload_3:
 443         state.spush();
 444         break;
 445       case Bytecodes::_lload:
 446       case Bytecodes::_dload:
 447       case Bytecodes::_lload_0:
 448       case Bytecodes::_lload_1:
 449       case Bytecodes::_lload_2:
 450       case Bytecodes::_lload_3:
 451       case Bytecodes::_dload_0:
 452       case Bytecodes::_dload_1:
 453       case Bytecodes::_dload_2:
 454       case Bytecodes::_dload_3:
 455         state.lpush();
 456         break;
 457       case Bytecodes::_aload_0:
 458         state.apush(state._vars[0]);
 459         break;
 460       case Bytecodes::_aload_1:
 461         state.apush(state._vars[1]);
 462         break;
 463       case Bytecodes::_aload_2:
 464         state.apush(state._vars[2]);
 465         break;
 466       case Bytecodes::_aload_3:
 467         state.apush(state._vars[3]);
 468         break;
 469       case Bytecodes::_iaload:
 470       case Bytecodes::_faload:
 471       case Bytecodes::_baload:
 472       case Bytecodes::_caload:
 473       case Bytecodes::_saload:
 474         state.spop();
 475         set_method_escape(state.apop());
 476         state.spush();
 477         break;
 478       case Bytecodes::_laload:
 479       case Bytecodes::_daload:
 480         state.spop();
 481         set_method_escape(state.apop());
 482         state.lpush();
 483         break;
 484       case Bytecodes::_aaload:
 485         { state.spop();
 486           ArgumentMap array = state.apop();
 487           set_method_escape(array);
 488           state.apush(unknown_obj);
 489         }
 490         break;
 491       case Bytecodes::_istore:
 492       case Bytecodes::_fstore:
 493       case Bytecodes::_istore_0:
 494       case Bytecodes::_istore_1:
 495       case Bytecodes::_istore_2:
 496       case Bytecodes::_istore_3:
 497       case Bytecodes::_fstore_0:
 498       case Bytecodes::_fstore_1:
 499       case Bytecodes::_fstore_2:
 500       case Bytecodes::_fstore_3:
 501         state.spop();
 502         break;
 503       case Bytecodes::_lstore:
 504       case Bytecodes::_dstore:
 505       case Bytecodes::_lstore_0:
 506       case Bytecodes::_lstore_1:
 507       case Bytecodes::_lstore_2:
 508       case Bytecodes::_lstore_3:
 509       case Bytecodes::_dstore_0:
 510       case Bytecodes::_dstore_1:
 511       case Bytecodes::_dstore_2:
 512       case Bytecodes::_dstore_3:
 513         state.lpop();
 514         break;
 515       case Bytecodes::_astore:
 516         state._vars[s.get_index()] = state.apop();
 517         break;
 518       case Bytecodes::_astore_0:
 519         state._vars[0] = state.apop();
 520         break;
 521       case Bytecodes::_astore_1:
 522         state._vars[1] = state.apop();
 523         break;
 524       case Bytecodes::_astore_2:
 525         state._vars[2] = state.apop();
 526         break;
 527       case Bytecodes::_astore_3:
 528         state._vars[3] = state.apop();
 529         break;
 530       case Bytecodes::_iastore:
 531       case Bytecodes::_fastore:
 532       case Bytecodes::_bastore:
 533       case Bytecodes::_castore:
 534       case Bytecodes::_sastore:
 535       {
 536         state.spop();
 537         state.spop();
 538         ArgumentMap arr = state.apop();
 539         set_method_escape(arr);
 540         set_modified(arr, OFFSET_ANY, type2size[T_INT]*HeapWordSize);
 541         break;
 542       }
 543       case Bytecodes::_lastore:
 544       case Bytecodes::_dastore:
 545       {
 546         state.lpop();
 547         state.spop();
 548         ArgumentMap arr = state.apop();
 549         set_method_escape(arr);
 550         set_modified(arr, OFFSET_ANY, type2size[T_LONG]*HeapWordSize);
 551         break;
 552       }
 553       case Bytecodes::_aastore:
 554       {
 555         set_global_escape(state.apop());
 556         state.spop();
 557         ArgumentMap arr = state.apop();
 558         set_modified(arr, OFFSET_ANY, type2size[T_OBJECT]*HeapWordSize);
 559         break;
 560       }
 561       case Bytecodes::_pop:
 562         state.raw_pop();
 563         break;
 564       case Bytecodes::_pop2:
 565         state.raw_pop();
 566         state.raw_pop();
 567         break;
 568       case Bytecodes::_dup:
 569         { ArgumentMap w1 = state.raw_pop();
 570           state.raw_push(w1);
 571           state.raw_push(w1);
 572         }
 573         break;
 574       case Bytecodes::_dup_x1:
 575         { ArgumentMap w1 = state.raw_pop();
 576           ArgumentMap w2 = state.raw_pop();
 577           state.raw_push(w1);
 578           state.raw_push(w2);
 579           state.raw_push(w1);
 580         }
 581         break;
 582       case Bytecodes::_dup_x2:
 583         { ArgumentMap w1 = state.raw_pop();
 584           ArgumentMap w2 = state.raw_pop();
 585           ArgumentMap w3 = state.raw_pop();
 586           state.raw_push(w1);
 587           state.raw_push(w3);
 588           state.raw_push(w2);
 589           state.raw_push(w1);
 590         }
 591         break;
 592       case Bytecodes::_dup2:
 593         { ArgumentMap w1 = state.raw_pop();
 594           ArgumentMap w2 = state.raw_pop();
 595           state.raw_push(w2);
 596           state.raw_push(w1);
 597           state.raw_push(w2);
 598           state.raw_push(w1);
 599         }
 600         break;
 601       case Bytecodes::_dup2_x1:
 602         { ArgumentMap w1 = state.raw_pop();
 603           ArgumentMap w2 = state.raw_pop();
 604           ArgumentMap w3 = state.raw_pop();
 605           state.raw_push(w2);
 606           state.raw_push(w1);
 607           state.raw_push(w3);
 608           state.raw_push(w2);
 609           state.raw_push(w1);
 610         }
 611         break;
 612       case Bytecodes::_dup2_x2:
 613         { ArgumentMap w1 = state.raw_pop();
 614           ArgumentMap w2 = state.raw_pop();
 615           ArgumentMap w3 = state.raw_pop();
 616           ArgumentMap w4 = state.raw_pop();
 617           state.raw_push(w2);
 618           state.raw_push(w1);
 619           state.raw_push(w4);
 620           state.raw_push(w3);
 621           state.raw_push(w2);
 622           state.raw_push(w1);
 623         }
 624         break;
 625       case Bytecodes::_swap:
 626         { ArgumentMap w1 = state.raw_pop();
 627           ArgumentMap w2 = state.raw_pop();
 628           state.raw_push(w1);
 629           state.raw_push(w2);
 630         }
 631         break;
 632       case Bytecodes::_iadd:
 633       case Bytecodes::_fadd:
 634       case Bytecodes::_isub:
 635       case Bytecodes::_fsub:
 636       case Bytecodes::_imul:
 637       case Bytecodes::_fmul:
 638       case Bytecodes::_idiv:
 639       case Bytecodes::_fdiv:
 640       case Bytecodes::_irem:
 641       case Bytecodes::_frem:
 642       case Bytecodes::_iand:
 643       case Bytecodes::_ior:
 644       case Bytecodes::_ixor:
 645         state.spop();
 646         state.spop();
 647         state.spush();
 648         break;
 649       case Bytecodes::_ladd:
 650       case Bytecodes::_dadd:
 651       case Bytecodes::_lsub:
 652       case Bytecodes::_dsub:
 653       case Bytecodes::_lmul:
 654       case Bytecodes::_dmul:
 655       case Bytecodes::_ldiv:
 656       case Bytecodes::_ddiv:
 657       case Bytecodes::_lrem:
 658       case Bytecodes::_drem:
 659       case Bytecodes::_land:
 660       case Bytecodes::_lor:
 661       case Bytecodes::_lxor:
 662         state.lpop();
 663         state.lpop();
 664         state.lpush();
 665         break;
 666       case Bytecodes::_ishl:
 667       case Bytecodes::_ishr:
 668       case Bytecodes::_iushr:
 669         state.spop();
 670         state.spop();
 671         state.spush();
 672         break;
 673       case Bytecodes::_lshl:
 674       case Bytecodes::_lshr:
 675       case Bytecodes::_lushr:
 676         state.spop();
 677         state.lpop();
 678         state.lpush();
 679         break;
 680       case Bytecodes::_ineg:
 681       case Bytecodes::_fneg:
 682         state.spop();
 683         state.spush();
 684         break;
 685       case Bytecodes::_lneg:
 686       case Bytecodes::_dneg:
 687         state.lpop();
 688         state.lpush();
 689         break;
 690       case Bytecodes::_iinc:
 691         break;
 692       case Bytecodes::_i2l:
 693       case Bytecodes::_i2d:
 694       case Bytecodes::_f2l:
 695       case Bytecodes::_f2d:
 696         state.spop();
 697         state.lpush();
 698         break;
 699       case Bytecodes::_i2f:
 700       case Bytecodes::_f2i:
 701         state.spop();
 702         state.spush();
 703         break;
 704       case Bytecodes::_l2i:
 705       case Bytecodes::_l2f:
 706       case Bytecodes::_d2i:
 707       case Bytecodes::_d2f:
 708         state.lpop();
 709         state.spush();
 710         break;
 711       case Bytecodes::_l2d:
 712       case Bytecodes::_d2l:
 713         state.lpop();
 714         state.lpush();
 715         break;
 716       case Bytecodes::_i2b:
 717       case Bytecodes::_i2c:
 718       case Bytecodes::_i2s:
 719         state.spop();
 720         state.spush();
 721         break;
 722       case Bytecodes::_lcmp:
 723       case Bytecodes::_dcmpl:
 724       case Bytecodes::_dcmpg:
 725         state.lpop();
 726         state.lpop();
 727         state.spush();
 728         break;
 729       case Bytecodes::_fcmpl:
 730       case Bytecodes::_fcmpg:
 731         state.spop();
 732         state.spop();
 733         state.spush();
 734         break;
 735       case Bytecodes::_ifeq:
 736       case Bytecodes::_ifne:
 737       case Bytecodes::_iflt:
 738       case Bytecodes::_ifge:
 739       case Bytecodes::_ifgt:
 740       case Bytecodes::_ifle:
 741       {
 742         state.spop();
 743         int dest_bci = s.get_dest();
 744         assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 745         assert(s.next_bci() == limit_bci, "branch must end block");
 746         successors.push(_methodBlocks->block_containing(dest_bci));
 747         break;
 748       }
 749       case Bytecodes::_if_icmpeq:
 750       case Bytecodes::_if_icmpne:
 751       case Bytecodes::_if_icmplt:
 752       case Bytecodes::_if_icmpge:
 753       case Bytecodes::_if_icmpgt:
 754       case Bytecodes::_if_icmple:
 755       {
 756         state.spop();
 757         state.spop();
 758         int dest_bci = s.get_dest();
 759         assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 760         assert(s.next_bci() == limit_bci, "branch must end block");
 761         successors.push(_methodBlocks->block_containing(dest_bci));
 762         break;
 763       }
 764       case Bytecodes::_if_acmpeq:
 765       case Bytecodes::_if_acmpne:
 766       {
 767         set_method_escape(state.apop());
 768         set_method_escape(state.apop());
 769         int dest_bci = s.get_dest();
 770         assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 771         assert(s.next_bci() == limit_bci, "branch must end block");
 772         successors.push(_methodBlocks->block_containing(dest_bci));
 773         break;
 774       }
 775       case Bytecodes::_goto:
 776       {
 777         int dest_bci = s.get_dest();
 778         assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 779         assert(s.next_bci() == limit_bci, "branch must end block");
 780         successors.push(_methodBlocks->block_containing(dest_bci));
 781         fall_through = false;
 782         break;
 783       }
 784       case Bytecodes::_jsr:
 785       {
 786         int dest_bci = s.get_dest();
 787         assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 788         assert(s.next_bci() == limit_bci, "branch must end block");
 789         state.apush(empty_map);
 790         successors.push(_methodBlocks->block_containing(dest_bci));
 791         fall_through = false;
 792         break;
 793       }
 794       case Bytecodes::_ret:
 795         // we don't track  the destination of a "ret" instruction
 796         assert(s.next_bci() == limit_bci, "branch must end block");
 797         fall_through = false;
 798         break;
 799       case Bytecodes::_return:
 800         assert(s.next_bci() == limit_bci, "return must end block");
 801         fall_through = false;
 802         break;
 803       case Bytecodes::_tableswitch:
 804         {
 805           state.spop();
 806           Bytecode_tableswitch sw(&s);
 807           int len = sw.length();
 808           int dest_bci;
 809           for (int i = 0; i < len; i++) {
 810             dest_bci = s.cur_bci() + sw.dest_offset_at(i);
 811             assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 812             successors.push(_methodBlocks->block_containing(dest_bci));
 813           }
 814           dest_bci = s.cur_bci() + sw.default_offset();
 815           assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 816           successors.push(_methodBlocks->block_containing(dest_bci));
 817           assert(s.next_bci() == limit_bci, "branch must end block");
 818           fall_through = false;
 819           break;
 820         }
 821       case Bytecodes::_lookupswitch:
 822         {
 823           state.spop();
 824           Bytecode_lookupswitch sw(&s);
 825           int len = sw.number_of_pairs();
 826           int dest_bci;
 827           for (int i = 0; i < len; i++) {
 828             dest_bci = s.cur_bci() + sw.pair_at(i).offset();
 829             assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 830             successors.push(_methodBlocks->block_containing(dest_bci));
 831           }
 832           dest_bci = s.cur_bci() + sw.default_offset();
 833           assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 834           successors.push(_methodBlocks->block_containing(dest_bci));
 835           fall_through = false;
 836           break;
 837         }
 838       case Bytecodes::_ireturn:
 839       case Bytecodes::_freturn:
 840         state.spop();
 841         fall_through = false;
 842         break;
 843       case Bytecodes::_lreturn:
 844       case Bytecodes::_dreturn:
 845         state.lpop();
 846         fall_through = false;
 847         break;
 848       case Bytecodes::_areturn:
 849         set_returned(state.apop());
 850         fall_through = false;
 851         break;
 852       case Bytecodes::_getstatic:
 853       case Bytecodes::_getfield:
 854         { bool ignored_will_link;
 855           ciField* field = s.get_field(ignored_will_link);
 856           BasicType field_type = field->type()->basic_type();
 857           if (s.cur_bc() != Bytecodes::_getstatic) {
 858             set_method_escape(state.apop());
 859           }
 860           if (is_reference_type(field_type)) {
 861             state.apush(unknown_obj);
 862           } else if (type2size[field_type] == 1) {
 863             state.spush();
 864           } else {
 865             state.lpush();
 866           }
 867         }
 868         break;
 869       case Bytecodes::_putstatic:
 870       case Bytecodes::_putfield:
 871         { bool will_link;
 872           ciField* field = s.get_field(will_link);
 873           BasicType field_type = field->type()->basic_type();
 874           if (is_reference_type(field_type)) {
 875             set_global_escape(state.apop());
 876           } else if (type2size[field_type] == 1) {
 877             state.spop();
 878           } else {
 879             state.lpop();
 880           }
 881           if (s.cur_bc() != Bytecodes::_putstatic) {
 882             ArgumentMap p = state.apop();
 883             set_method_escape(p);
 884             set_modified(p, will_link ? field->offset() : OFFSET_ANY, type2size[field_type]*HeapWordSize);
 885           }
 886         }
 887         break;
 888       case Bytecodes::_invokevirtual:
 889       case Bytecodes::_invokespecial:
 890       case Bytecodes::_invokestatic:
 891       case Bytecodes::_invokedynamic:
 892       case Bytecodes::_invokeinterface:
 893         { bool ignored_will_link;
 894           ciSignature* declared_signature = NULL;
 895           ciMethod* target = s.get_method(ignored_will_link, &declared_signature);
 896           ciKlass*  holder = s.get_declared_method_holder();
 897           assert(declared_signature != NULL, "cannot be null");
 898           // If the current bytecode has an attached appendix argument,
 899           // push an unknown object to represent that argument. (Analysis
 900           // of dynamic call sites, especially invokehandle calls, needs
 901           // the appendix argument on the stack, in addition to "regular" arguments
 902           // pushed onto the stack by bytecode instructions preceding the call.)
 903           //
 904           // The escape analyzer does _not_ use the ciBytecodeStream::has_appendix(s)
 905           // method to determine whether the current bytecode has an appendix argument.
 906           // The has_appendix() method obtains the appendix from the
 907           // ConstantPoolCacheEntry::_f1 field, which can happen concurrently with
 908           // resolution of dynamic call sites. Callees in the
 909           // ciBytecodeStream::get_method() call above also access the _f1 field;
 910           // interleaving the get_method() and has_appendix() calls in the current
 911           // method with call site resolution can lead to an inconsistent view of
 912           // the current method's argument count. In particular, some interleaving(s)
 913           // can cause the method's argument count to not include the appendix, which
 914           // then leads to stack over-/underflow in the escape analyzer.
 915           //
 916           // Instead of pushing the argument if has_appendix() is true, the escape analyzer
 917           // pushes an appendix for all call sites targeted by invokedynamic and invokehandle
 918           // instructions, except if the call site is the _invokeBasic intrinsic
 919           // (that intrinsic is always targeted by an invokehandle instruction but does
 920           // not have an appendix argument).
 921           if (target->is_loaded() &&
 922               Bytecodes::has_optional_appendix(s.cur_bc_raw()) &&
 923               target->intrinsic_id() != vmIntrinsics::_invokeBasic) {
 924             state.apush(unknown_obj);
 925           }
 926           // Pass in raw bytecode because we need to see invokehandle instructions.
 927           invoke(state, s.cur_bc_raw(), target, holder);
 928           // We are using the return type of the declared signature here because
 929           // it might be a more concrete type than the one from the target (for
 930           // e.g. invokedynamic and invokehandle).
 931           ciType* return_type = declared_signature->return_type();
 932           if (!return_type->is_primitive_type()) {
 933             state.apush(unknown_obj);
 934           } else if (return_type->is_one_word()) {
 935             state.spush();
 936           } else if (return_type->is_two_word()) {
 937             state.lpush();
 938           }
 939         }
 940         break;
 941       case Bytecodes::_new:
 942         state.apush(allocated_obj);
 943         break;
 944       case Bytecodes::_newarray:
 945       case Bytecodes::_anewarray:
 946         state.spop();
 947         state.apush(allocated_obj);
 948         break;
 949       case Bytecodes::_multianewarray:
 950         { int i = s.cur_bcp()[3];
 951           while (i-- > 0) state.spop();
 952           state.apush(allocated_obj);
 953         }
 954         break;
 955       case Bytecodes::_arraylength:
 956         set_method_escape(state.apop());
 957         state.spush();
 958         break;
 959       case Bytecodes::_athrow:
 960         set_global_escape(state.apop());
 961         fall_through = false;
 962         break;
 963       case Bytecodes::_checkcast:
 964         { ArgumentMap obj = state.apop();
 965           set_method_escape(obj);
 966           state.apush(obj);
 967         }
 968         break;
 969       case Bytecodes::_instanceof:
 970         set_method_escape(state.apop());
 971         state.spush();
 972         break;
 973       case Bytecodes::_monitorenter:
 974       case Bytecodes::_monitorexit:
 975         state.apop();
 976         break;
 977       case Bytecodes::_wide:
 978         ShouldNotReachHere();
 979         break;
 980       case Bytecodes::_ifnull:
 981       case Bytecodes::_ifnonnull:
 982       {
 983         set_method_escape(state.apop());
 984         int dest_bci = s.get_dest();
 985         assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 986         assert(s.next_bci() == limit_bci, "branch must end block");
 987         successors.push(_methodBlocks->block_containing(dest_bci));
 988         break;
 989       }
 990       case Bytecodes::_goto_w:
 991       {
 992         int dest_bci = s.get_far_dest();
 993         assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
 994         assert(s.next_bci() == limit_bci, "branch must end block");
 995         successors.push(_methodBlocks->block_containing(dest_bci));
 996         fall_through = false;
 997         break;
 998       }
 999       case Bytecodes::_jsr_w:
1000       {
1001         int dest_bci = s.get_far_dest();
1002         assert(_methodBlocks->is_block_start(dest_bci), "branch destination must start a block");
1003         assert(s.next_bci() == limit_bci, "branch must end block");
1004         state.apush(empty_map);
1005         successors.push(_methodBlocks->block_containing(dest_bci));
1006         fall_through = false;
1007         break;
1008       }
1009       case Bytecodes::_breakpoint:
1010         break;
1011       default:
1012         ShouldNotReachHere();
1013         break;
1014     }
1015 
1016   }
1017   if (fall_through) {
1018     int fall_through_bci = s.cur_bci();
1019     if (fall_through_bci < _method->code_size()) {
1020       assert(_methodBlocks->is_block_start(fall_through_bci), "must fall through to block start.");
1021       successors.push(_methodBlocks->block_containing(fall_through_bci));
1022     }
1023   }
1024 }
1025 
1026 void BCEscapeAnalyzer::merge_block_states(StateInfo *blockstates, ciBlock *dest, StateInfo *s_state) {
1027   StateInfo *d_state = blockstates + dest->index();
1028   int nlocals = _method->max_locals();
1029 
1030   // exceptions may cause transfer of control to handlers in the middle of a
1031   // block, so we don't merge the incoming state of exception handlers
1032   if (dest->is_handler())
1033     return;
1034   if (!d_state->_initialized ) {
1035     // destination not initialized, just copy
1036     for (int i = 0; i < nlocals; i++) {
1037       d_state->_vars[i] = s_state->_vars[i];
1038     }
1039     for (int i = 0; i < s_state->_stack_height; i++) {
1040       d_state->_stack[i] = s_state->_stack[i];
1041     }
1042     d_state->_stack_height = s_state->_stack_height;
1043     d_state->_max_stack = s_state->_max_stack;
1044     d_state->_initialized = true;
1045   } else if (!dest->processed()) {
1046     // we have not yet walked the bytecodes of dest, we can merge
1047     // the states
1048     assert(d_state->_stack_height == s_state->_stack_height, "computed stack heights must match");
1049     for (int i = 0; i < nlocals; i++) {
1050       d_state->_vars[i].set_union(s_state->_vars[i]);
1051     }
1052     for (int i = 0; i < s_state->_stack_height; i++) {
1053       d_state->_stack[i].set_union(s_state->_stack[i]);
1054     }
1055   } else {
1056     // the bytecodes of dest have already been processed, mark any
1057     // arguments in the source state which are not in the dest state
1058     // as global escape.
1059     // Future refinement:  we only need to mark these variable to the
1060     // maximum escape of any variables in dest state
1061     assert(d_state->_stack_height == s_state->_stack_height, "computed stack heights must match");
1062     ArgumentMap extra_vars;
1063     for (int i = 0; i < nlocals; i++) {
1064       ArgumentMap t;
1065       t = s_state->_vars[i];
1066       t.set_difference(d_state->_vars[i]);
1067       extra_vars.set_union(t);
1068     }
1069     for (int i = 0; i < s_state->_stack_height; i++) {
1070       ArgumentMap t;
1071       //extra_vars |= !d_state->_vars[i] & s_state->_vars[i];
1072       t.clear();
1073       t = s_state->_stack[i];
1074       t.set_difference(d_state->_stack[i]);
1075       extra_vars.set_union(t);
1076     }
1077     set_global_escape(extra_vars, true);
1078   }
1079 }
1080 
1081 void BCEscapeAnalyzer::iterate_blocks(Arena *arena) {
1082   int numblocks = _methodBlocks->num_blocks();
1083   int stkSize   = _method->max_stack();
1084   int numLocals = _method->max_locals();
1085   StateInfo state;
1086 
1087   int datacount = (numblocks + 1) * (stkSize + numLocals);
1088   int datasize = datacount * sizeof(ArgumentMap);
1089   StateInfo *blockstates = (StateInfo *) arena->Amalloc(numblocks * sizeof(StateInfo));
1090   ArgumentMap *statedata  = (ArgumentMap *) arena->Amalloc(datasize);
1091   for (int i = 0; i < datacount; i++) ::new ((void*)&statedata[i]) ArgumentMap();
1092   ArgumentMap *dp = statedata;
1093   state._vars = dp;
1094   dp += numLocals;
1095   state._stack = dp;
1096   dp += stkSize;
1097   state._initialized = false;
1098   state._max_stack = stkSize;
1099   for (int i = 0; i < numblocks; i++) {
1100     blockstates[i]._vars = dp;
1101     dp += numLocals;
1102     blockstates[i]._stack = dp;
1103     dp += stkSize;
1104     blockstates[i]._initialized = false;
1105     blockstates[i]._stack_height = 0;
1106     blockstates[i]._max_stack  = stkSize;
1107   }
1108   GrowableArray<ciBlock *> worklist(arena, numblocks / 4, 0, NULL);
1109   GrowableArray<ciBlock *> successors(arena, 4, 0, NULL);
1110 
1111   _methodBlocks->clear_processed();
1112 
1113   // initialize block 0 state from method signature
1114   ArgumentMap allVars;   // all oop arguments to method
1115   ciSignature* sig = method()->signature();
1116   int j = 0;
1117   ciBlock* first_blk = _methodBlocks->block_containing(0);
1118   int fb_i = first_blk->index();
1119   if (!method()->is_static()) {
1120     // record information for "this"
1121     blockstates[fb_i]._vars[j].set(j);
1122     allVars.add(j);
1123     j++;
1124   }
1125   for (int i = 0; i < sig->count(); i++) {
1126     ciType* t = sig->type_at(i);
1127     if (!t->is_primitive_type()) {
1128       blockstates[fb_i]._vars[j].set(j);
1129       allVars.add(j);
1130     }
1131     j += t->size();
1132   }
1133   blockstates[fb_i]._initialized = true;
1134   assert(j == _arg_size, "just checking");
1135 
1136   ArgumentMap unknown_map;
1137   unknown_map.add_unknown();
1138 
1139   worklist.push(first_blk);
1140   while(worklist.length() > 0) {
1141     ciBlock *blk = worklist.pop();
1142     StateInfo *blkState = blockstates + blk->index();
1143     if (blk->is_handler() || blk->is_ret_target()) {
1144       // for an exception handler or a target of a ret instruction, we assume the worst case,
1145       // that any variable could contain any argument
1146       for (int i = 0; i < numLocals; i++) {
1147         state._vars[i] = allVars;
1148       }
1149       if (blk->is_handler()) {
1150         state._stack_height = 1;
1151       } else {
1152         state._stack_height = blkState->_stack_height;
1153       }
1154       for (int i = 0; i < state._stack_height; i++) {
1155 // ??? should this be unknown_map ???
1156         state._stack[i] = allVars;
1157       }
1158     } else {
1159       for (int i = 0; i < numLocals; i++) {
1160         state._vars[i] = blkState->_vars[i];
1161       }
1162       for (int i = 0; i < blkState->_stack_height; i++) {
1163         state._stack[i] = blkState->_stack[i];
1164       }
1165       state._stack_height = blkState->_stack_height;
1166     }
1167     iterate_one_block(blk, state, successors);
1168     // if this block has any exception handlers, push them
1169     // onto successor list
1170     if (blk->has_handler()) {
1171       DEBUG_ONLY(int handler_count = 0;)
1172       int blk_start = blk->start_bci();
1173       int blk_end = blk->limit_bci();
1174       for (int i = 0; i < numblocks; i++) {
1175         ciBlock *b = _methodBlocks->block(i);
1176         if (b->is_handler()) {
1177           int ex_start = b->ex_start_bci();
1178           int ex_end = b->ex_limit_bci();
1179           if ((ex_start >= blk_start && ex_start < blk_end) ||
1180               (ex_end > blk_start && ex_end <= blk_end)) {
1181             successors.push(b);
1182           }
1183           DEBUG_ONLY(handler_count++;)
1184         }
1185       }
1186       assert(handler_count > 0, "must find at least one handler");
1187     }
1188     // merge computed variable state with successors
1189     while(successors.length() > 0) {
1190       ciBlock *succ = successors.pop();
1191       merge_block_states(blockstates, succ, &state);
1192       if (!succ->processed())
1193         worklist.push(succ);
1194     }
1195   }
1196 }
1197 
1198 void BCEscapeAnalyzer::do_analysis() {
1199   Arena* arena = CURRENT_ENV->arena();
1200   // identify basic blocks
1201   _methodBlocks = _method->get_method_blocks();
1202 
1203   iterate_blocks(arena);
1204 }
1205 
1206 vmIntrinsicID BCEscapeAnalyzer::known_intrinsic() {
1207   vmIntrinsicID iid = method()->intrinsic_id();
1208   if (iid == vmIntrinsics::_getClass ||
1209       iid == vmIntrinsics::_hashCode) {
1210     return iid;
1211   } else {
1212     return vmIntrinsics::_none;
1213   }
1214 }
1215 
1216 void BCEscapeAnalyzer::compute_escape_for_intrinsic(vmIntrinsicID iid) {
1217   switch (iid) {
1218     case vmIntrinsics::_getClass:
1219       _return_local = false;
1220       _return_allocated = false;
1221       break;
1222     case vmIntrinsics::_hashCode:
1223       // initialized state is correct
1224       break;
1225   default:
1226     assert(false, "unexpected intrinsic");
1227   }
1228 }
1229 
1230 void BCEscapeAnalyzer::initialize() {
1231   int i;
1232 
1233   // clear escape information (method may have been deoptimized)
1234   methodData()->clear_escape_info();
1235 
1236   // initialize escape state of object parameters
1237   ciSignature* sig = method()->signature();
1238   int j = 0;
1239   if (!method()->is_static()) {
1240     _arg_local.set(0);
1241     _arg_stack.set(0);
1242     j++;
1243   }
1244   for (i = 0; i < sig->count(); i++) {
1245     ciType* t = sig->type_at(i);
1246     if (!t->is_primitive_type()) {
1247       _arg_local.set(j);
1248       _arg_stack.set(j);
1249     }
1250     j += t->size();
1251   }
1252   assert(j == _arg_size, "just checking");
1253 
1254   // start with optimistic assumption
1255   ciType *rt = _method->return_type();
1256   if (rt->is_primitive_type()) {
1257     _return_local = false;
1258     _return_allocated = false;
1259   } else {
1260     _return_local = true;
1261     _return_allocated = true;
1262   }
1263   _allocated_escapes = false;
1264   _unknown_modified = false;
1265 }
1266 
1267 void BCEscapeAnalyzer::clear_escape_info() {
1268   ciSignature* sig = method()->signature();
1269   int arg_count = sig->count();
1270   ArgumentMap var;
1271   if (!method()->is_static()) {
1272     arg_count++;  // allow for "this"
1273   }
1274   for (int i = 0; i < arg_count; i++) {
1275     set_arg_modified(i, OFFSET_ANY, 4);
1276     var.clear();
1277     var.set(i);
1278     set_modified(var, OFFSET_ANY, 4);
1279     set_global_escape(var);
1280   }
1281   _arg_local.clear();
1282   _arg_stack.clear();
1283   _arg_returned.clear();
1284   _return_local = false;
1285   _return_allocated = false;
1286   _allocated_escapes = true;
1287   _unknown_modified = true;
1288 }
1289 
1290 
1291 void BCEscapeAnalyzer::compute_escape_info() {
1292   int i;
1293   assert(!methodData()->has_escape_info(), "do not overwrite escape info");
1294 
1295   vmIntrinsicID iid = known_intrinsic();
1296 
1297   // check if method can be analyzed
1298   if (iid == vmIntrinsics::_none && (method()->is_abstract() || method()->is_native() || !method()->holder()->is_initialized()
1299       || _level > MaxBCEAEstimateLevel
1300       || method()->code_size() > MaxBCEAEstimateSize)) {
1301     if (BCEATraceLevel >= 1) {
1302       tty->print("Skipping method because: ");
1303       if (method()->is_abstract())
1304         tty->print_cr("method is abstract.");
1305       else if (method()->is_native())
1306         tty->print_cr("method is native.");
1307       else if (!method()->holder()->is_initialized())
1308         tty->print_cr("class of method is not initialized.");
1309       else if (_level > MaxBCEAEstimateLevel)
1310         tty->print_cr("level (%d) exceeds MaxBCEAEstimateLevel (%d).",
1311                       _level, (int) MaxBCEAEstimateLevel);
1312       else if (method()->code_size() > MaxBCEAEstimateSize)
1313         tty->print_cr("code size (%d) exceeds MaxBCEAEstimateSize (%d).",
1314                       method()->code_size(), (int) MaxBCEAEstimateSize);
1315       else
1316         ShouldNotReachHere();
1317     }
1318     clear_escape_info();
1319 
1320     return;
1321   }
1322 
1323   if (BCEATraceLevel >= 1) {
1324     tty->print("[EA] estimating escape information for");
1325     if (iid != vmIntrinsics::_none)
1326       tty->print(" intrinsic");
1327     method()->print_short_name();
1328     tty->print_cr(" (%d bytes)", method()->code_size());
1329   }
1330 
1331   initialize();
1332 
1333   // Do not scan method if it has no object parameters and
1334   // does not returns an object (_return_allocated is set in initialize()).
1335   if (_arg_local.is_empty() && !_return_allocated) {
1336     // Clear all info since method's bytecode was not analysed and
1337     // set pessimistic escape information.
1338     clear_escape_info();
1339     methodData()->set_eflag(MethodData::allocated_escapes);
1340     methodData()->set_eflag(MethodData::unknown_modified);
1341     methodData()->set_eflag(MethodData::estimated);
1342     return;
1343   }
1344 
1345   if (iid != vmIntrinsics::_none)
1346     compute_escape_for_intrinsic(iid);
1347   else {
1348     do_analysis();
1349   }
1350 
1351   // don't store interprocedural escape information if it introduces
1352   // dependencies or if method data is empty
1353   //
1354   if (!has_dependencies() && !methodData()->is_empty()) {
1355     for (i = 0; i < _arg_size; i++) {
1356       if (_arg_local.test(i)) {
1357         assert(_arg_stack.test(i), "inconsistent escape info");
1358         methodData()->set_arg_local(i);
1359         methodData()->set_arg_stack(i);
1360       } else if (_arg_stack.test(i)) {
1361         methodData()->set_arg_stack(i);
1362       }
1363       if (_arg_returned.test(i)) {
1364         methodData()->set_arg_returned(i);
1365       }
1366       methodData()->set_arg_modified(i, _arg_modified[i]);
1367     }
1368     if (_return_local) {
1369       methodData()->set_eflag(MethodData::return_local);
1370     }
1371     if (_return_allocated) {
1372       methodData()->set_eflag(MethodData::return_allocated);
1373     }
1374     if (_allocated_escapes) {
1375       methodData()->set_eflag(MethodData::allocated_escapes);
1376     }
1377     if (_unknown_modified) {
1378       methodData()->set_eflag(MethodData::unknown_modified);
1379     }
1380     methodData()->set_eflag(MethodData::estimated);
1381   }
1382 }
1383 
1384 void BCEscapeAnalyzer::read_escape_info() {
1385   assert(methodData()->has_escape_info(), "no escape info available");
1386 
1387   // read escape information from method descriptor
1388   for (int i = 0; i < _arg_size; i++) {
1389     if (methodData()->is_arg_local(i))
1390       _arg_local.set(i);
1391     if (methodData()->is_arg_stack(i))
1392       _arg_stack.set(i);
1393     if (methodData()->is_arg_returned(i))
1394       _arg_returned.set(i);
1395     _arg_modified[i] = methodData()->arg_modified(i);
1396   }
1397   _return_local = methodData()->eflag_set(MethodData::return_local);
1398   _return_allocated = methodData()->eflag_set(MethodData::return_allocated);
1399   _allocated_escapes = methodData()->eflag_set(MethodData::allocated_escapes);
1400   _unknown_modified = methodData()->eflag_set(MethodData::unknown_modified);
1401 
1402 }
1403 
1404 #ifndef PRODUCT
1405 void BCEscapeAnalyzer::dump() {
1406   tty->print("[EA] estimated escape information for");
1407   method()->print_short_name();
1408   tty->print_cr(has_dependencies() ? " (not stored)" : "");
1409   tty->print("     non-escaping args:      ");
1410   _arg_local.print();
1411   tty->print("     stack-allocatable args: ");
1412   _arg_stack.print();
1413   if (_return_local) {
1414     tty->print("     returned args:          ");
1415     _arg_returned.print();
1416   } else if (is_return_allocated()) {
1417     tty->print_cr("     return allocated value");
1418   } else {
1419     tty->print_cr("     return non-local value");
1420   }
1421   tty->print("     modified args: ");
1422   for (int i = 0; i < _arg_size; i++) {
1423     if (_arg_modified[i] == 0)
1424       tty->print("    0");
1425     else
1426       tty->print("    0x%x", _arg_modified[i]);
1427   }
1428   tty->cr();
1429   tty->print("     flags: ");
1430   if (_return_allocated)
1431     tty->print(" return_allocated");
1432   if (_allocated_escapes)
1433     tty->print(" allocated_escapes");
1434   if (_unknown_modified)
1435     tty->print(" unknown_modified");
1436   tty->cr();
1437 }
1438 #endif
1439 
1440 BCEscapeAnalyzer::BCEscapeAnalyzer(ciMethod* method, BCEscapeAnalyzer* parent)
1441     : _arena(CURRENT_ENV->arena())
1442     , _conservative(method == NULL || !EstimateArgEscape)
1443     , _method(method)
1444     , _methodData(method ? method->method_data() : NULL)
1445     , _arg_size(method ? method->arg_size() : 0)
1446     , _arg_local(_arena)
1447     , _arg_stack(_arena)
1448     , _arg_returned(_arena)
1449     , _return_local(false)
1450     , _return_allocated(false)
1451     , _allocated_escapes(false)
1452     , _unknown_modified(false)
1453     , _dependencies(_arena, 4, 0, NULL)
1454     , _parent(parent)
1455     , _level(parent == NULL ? 0 : parent->level() + 1) {
1456   if (!_conservative) {
1457     _arg_local.clear();
1458     _arg_stack.clear();
1459     _arg_returned.clear();
1460     Arena* arena = CURRENT_ENV->arena();
1461     _arg_modified = (uint *) arena->Amalloc(_arg_size * sizeof(uint));
1462     Copy::zero_to_bytes(_arg_modified, _arg_size * sizeof(uint));
1463 
1464     if (methodData() == NULL)
1465       return;
1466     if (methodData()->has_escape_info()) {
1467       TRACE_BCEA(2, tty->print_cr("[EA] Reading previous results for %s.%s",
1468                                   method->holder()->name()->as_utf8(),
1469                                   method->name()->as_utf8()));
1470       read_escape_info();
1471     } else {
1472       TRACE_BCEA(2, tty->print_cr("[EA] computing results for %s.%s",
1473                                   method->holder()->name()->as_utf8(),
1474                                   method->name()->as_utf8()));
1475 
1476       compute_escape_info();
1477       methodData()->update_escape_info();
1478     }
1479 #ifndef PRODUCT
1480     if (BCEATraceLevel >= 3) {
1481       // dump escape information
1482       dump();
1483     }
1484 #endif
1485   }
1486 }
1487 
1488 void BCEscapeAnalyzer::copy_dependencies(Dependencies *deps) {
1489   if (ciEnv::current()->jvmti_can_hotswap_or_post_breakpoint()) {
1490     // Also record evol dependencies so redefinition of the
1491     // callee will trigger recompilation.
1492     deps->assert_evol_method(method());
1493   }
1494   for (int i = 0; i < _dependencies.length(); i+=4) {
1495     ciKlass*  recv_klass      = _dependencies.at(i+0)->as_klass();
1496     ciMethod* target          = _dependencies.at(i+1)->as_method();
1497     ciKlass*  resolved_klass  = _dependencies.at(i+2)->as_klass();
1498     ciMethod* resolved_method = _dependencies.at(i+3)->as_method();
1499     deps->assert_unique_concrete_method(recv_klass, target, resolved_klass, resolved_method);
1500   }
1501 }