1 /*
   2  * Copyright (c) 2000, 2013, 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/systemDictionary.hpp"
  27 #include "interpreter/bytecode.hpp"
  28 #include "interpreter/bytecodeStream.hpp"
  29 #include "interpreter/linkResolver.hpp"
  30 #include "memory/heapInspection.hpp"
  31 #include "oops/methodData.hpp"
  32 #include "prims/jvmtiRedefineClasses.hpp"
  33 #include "runtime/compilationPolicy.hpp"
  34 #include "runtime/deoptimization.hpp"
  35 #include "runtime/handles.inline.hpp"
  36 
  37 // ==================================================================
  38 // DataLayout
  39 //
  40 // Overlay for generic profiling data.
  41 
  42 // Some types of data layouts need a length field.
  43 bool DataLayout::needs_array_len(u1 tag) {
  44   return (tag == multi_branch_data_tag) || (tag == arg_info_data_tag);
  45 }
  46 
  47 // Perform generic initialization of the data.  More specific
  48 // initialization occurs in overrides of ProfileData::post_initialize.
  49 void DataLayout::initialize(u1 tag, u2 bci, int cell_count) {
  50   _header._bits = (intptr_t)0;
  51   _header._struct._tag = tag;
  52   _header._struct._bci = bci;
  53   for (int i = 0; i < cell_count; i++) {
  54     set_cell_at(i, (intptr_t)0);
  55   }
  56   if (needs_array_len(tag)) {
  57     set_cell_at(ArrayData::array_len_off_set, cell_count - 1); // -1 for header.
  58   }
  59 }
  60 
  61 void DataLayout::clean_weak_klass_links(BoolObjectClosure* cl) {
  62   ResourceMark m;
  63   data_in()->clean_weak_klass_links(cl);
  64 }
  65 
  66 
  67 // ==================================================================
  68 // ProfileData
  69 //
  70 // A ProfileData object is created to refer to a section of profiling
  71 // data in a structured way.
  72 
  73 // Constructor for invalid ProfileData.
  74 ProfileData::ProfileData() {
  75   _data = NULL;
  76 }
  77 
  78 #ifndef PRODUCT
  79 void ProfileData::print_shared(outputStream* st, const char* name) {
  80   st->print("bci: %d", bci());
  81   st->fill_to(tab_width_one);
  82   st->print("%s", name);
  83   tab(st);
  84   int trap = trap_state();
  85   if (trap != 0) {
  86     char buf[100];
  87     st->print("trap(%s) ", Deoptimization::format_trap_state(buf, sizeof(buf), trap));
  88   }
  89   int flags = data()->flags();
  90   if (flags != 0)
  91     st->print("flags(%d) ", flags);
  92 }
  93 
  94 void ProfileData::tab(outputStream* st) {
  95   st->fill_to(tab_width_two);
  96 }
  97 #endif // !PRODUCT
  98 
  99 // ==================================================================
 100 // BitData
 101 //
 102 // A BitData corresponds to a one-bit flag.  This is used to indicate
 103 // whether a checkcast bytecode has seen a null value.
 104 
 105 
 106 #ifndef PRODUCT
 107 void BitData::print_data_on(outputStream* st) {
 108   print_shared(st, "BitData");
 109 }
 110 #endif // !PRODUCT
 111 
 112 // ==================================================================
 113 // CounterData
 114 //
 115 // A CounterData corresponds to a simple counter.
 116 
 117 #ifndef PRODUCT
 118 void CounterData::print_data_on(outputStream* st) {
 119   print_shared(st, "CounterData");
 120   st->print_cr("count(%u)", count());
 121 }
 122 #endif // !PRODUCT
 123 
 124 // ==================================================================
 125 // JumpData
 126 //
 127 // A JumpData is used to access profiling information for a direct
 128 // branch.  It is a counter, used for counting the number of branches,
 129 // plus a data displacement, used for realigning the data pointer to
 130 // the corresponding target bci.
 131 
 132 void JumpData::post_initialize(BytecodeStream* stream, MethodData* mdo) {
 133   assert(stream->bci() == bci(), "wrong pos");
 134   int target;
 135   Bytecodes::Code c = stream->code();
 136   if (c == Bytecodes::_goto_w || c == Bytecodes::_jsr_w) {
 137     target = stream->dest_w();
 138   } else {
 139     target = stream->dest();
 140   }
 141   int my_di = mdo->dp_to_di(dp());
 142   int target_di = mdo->bci_to_di(target);
 143   int offset = target_di - my_di;
 144   set_displacement(offset);
 145 }
 146 
 147 #ifndef PRODUCT
 148 void JumpData::print_data_on(outputStream* st) {
 149   print_shared(st, "JumpData");
 150   st->print_cr("taken(%u) displacement(%d)", taken(), displacement());
 151 }
 152 #endif // !PRODUCT
 153 
 154 // ==================================================================
 155 // ReceiverTypeData
 156 //
 157 // A ReceiverTypeData is used to access profiling information about a
 158 // dynamic type check.  It consists of a counter which counts the total times
 159 // that the check is reached, and a series of (Klass*, count) pairs
 160 // which are used to store a type profile for the receiver of the check.
 161 
 162 void ReceiverTypeData::clean_weak_klass_links(BoolObjectClosure* is_alive_cl) {
 163     for (uint row = 0; row < row_limit(); row++) {
 164     Klass* p = receiver(row);
 165     if (p != NULL && !p->is_loader_alive(is_alive_cl)) {
 166       clear_row(row);
 167     }
 168   }
 169 }
 170 
 171 #ifndef PRODUCT
 172 void ReceiverTypeData::print_receiver_data_on(outputStream* st) {
 173   uint row;
 174   int entries = 0;
 175   for (row = 0; row < row_limit(); row++) {
 176     if (receiver(row) != NULL)  entries++;
 177   }
 178   st->print_cr("count(%u) entries(%u)", count(), entries);
 179   int total = count();
 180   for (row = 0; row < row_limit(); row++) {
 181     if (receiver(row) != NULL) {
 182       total += receiver_count(row);
 183     }
 184   }
 185   for (row = 0; row < row_limit(); row++) {
 186     if (receiver(row) != NULL) {
 187       tab(st);
 188       receiver(row)->print_value_on(st);
 189       st->print_cr("(%u %4.2f)", receiver_count(row), (float) receiver_count(row) / (float) total);
 190     }
 191   }
 192 }
 193 void ReceiverTypeData::print_data_on(outputStream* st) {
 194   print_shared(st, "ReceiverTypeData");
 195   print_receiver_data_on(st);
 196 }
 197 void VirtualCallData::print_data_on(outputStream* st) {
 198   print_shared(st, "VirtualCallData");
 199   print_receiver_data_on(st);
 200 }
 201 #endif // !PRODUCT
 202 
 203 // ==================================================================
 204 // RetData
 205 //
 206 // A RetData is used to access profiling information for a ret bytecode.
 207 // It is composed of a count of the number of times that the ret has
 208 // been executed, followed by a series of triples of the form
 209 // (bci, count, di) which count the number of times that some bci was the
 210 // target of the ret and cache a corresponding displacement.
 211 
 212 void RetData::post_initialize(BytecodeStream* stream, MethodData* mdo) {
 213   for (uint row = 0; row < row_limit(); row++) {
 214     set_bci_displacement(row, -1);
 215     set_bci(row, no_bci);
 216   }
 217   // release so other threads see a consistent state.  bci is used as
 218   // a valid flag for bci_displacement.
 219   OrderAccess::release();
 220 }
 221 
 222 // This routine needs to atomically update the RetData structure, so the
 223 // caller needs to hold the RetData_lock before it gets here.  Since taking
 224 // the lock can block (and allow GC) and since RetData is a ProfileData is a
 225 // wrapper around a derived oop, taking the lock in _this_ method will
 226 // basically cause the 'this' pointer's _data field to contain junk after the
 227 // lock.  We require the caller to take the lock before making the ProfileData
 228 // structure.  Currently the only caller is InterpreterRuntime::update_mdp_for_ret
 229 address RetData::fixup_ret(int return_bci, MethodData* h_mdo) {
 230   // First find the mdp which corresponds to the return bci.
 231   address mdp = h_mdo->bci_to_dp(return_bci);
 232 
 233   // Now check to see if any of the cache slots are open.
 234   for (uint row = 0; row < row_limit(); row++) {
 235     if (bci(row) == no_bci) {
 236       set_bci_displacement(row, mdp - dp());
 237       set_bci_count(row, DataLayout::counter_increment);
 238       // Barrier to ensure displacement is written before the bci; allows
 239       // the interpreter to read displacement without fear of race condition.
 240       release_set_bci(row, return_bci);
 241       break;
 242     }
 243   }
 244   return mdp;
 245 }
 246 
 247 
 248 #ifndef PRODUCT
 249 void RetData::print_data_on(outputStream* st) {
 250   print_shared(st, "RetData");
 251   uint row;
 252   int entries = 0;
 253   for (row = 0; row < row_limit(); row++) {
 254     if (bci(row) != no_bci)  entries++;
 255   }
 256   st->print_cr("count(%u) entries(%u)", count(), entries);
 257   for (row = 0; row < row_limit(); row++) {
 258     if (bci(row) != no_bci) {
 259       tab(st);
 260       st->print_cr("bci(%d: count(%u) displacement(%d))",
 261                    bci(row), bci_count(row), bci_displacement(row));
 262     }
 263   }
 264 }
 265 #endif // !PRODUCT
 266 
 267 // ==================================================================
 268 // BranchData
 269 //
 270 // A BranchData is used to access profiling data for a two-way branch.
 271 // It consists of taken and not_taken counts as well as a data displacement
 272 // for the taken case.
 273 
 274 void BranchData::post_initialize(BytecodeStream* stream, MethodData* mdo) {
 275   assert(stream->bci() == bci(), "wrong pos");
 276   int target = stream->dest();
 277   int my_di = mdo->dp_to_di(dp());
 278   int target_di = mdo->bci_to_di(target);
 279   int offset = target_di - my_di;
 280   set_displacement(offset);
 281 }
 282 
 283 #ifndef PRODUCT
 284 void BranchData::print_data_on(outputStream* st) {
 285   print_shared(st, "BranchData");
 286   st->print_cr("taken(%u) displacement(%d)",
 287                taken(), displacement());
 288   tab(st);
 289   st->print_cr("not taken(%u)", not_taken());
 290 }
 291 #endif
 292 
 293 // ==================================================================
 294 // MultiBranchData
 295 //
 296 // A MultiBranchData is used to access profiling information for
 297 // a multi-way branch (*switch bytecodes).  It consists of a series
 298 // of (count, displacement) pairs, which count the number of times each
 299 // case was taken and specify the data displacment for each branch target.
 300 
 301 int MultiBranchData::compute_cell_count(BytecodeStream* stream) {
 302   int cell_count = 0;
 303   if (stream->code() == Bytecodes::_tableswitch) {
 304     Bytecode_tableswitch sw(stream->method()(), stream->bcp());
 305     cell_count = 1 + per_case_cell_count * (1 + sw.length()); // 1 for default
 306   } else {
 307     Bytecode_lookupswitch sw(stream->method()(), stream->bcp());
 308     cell_count = 1 + per_case_cell_count * (sw.number_of_pairs() + 1); // 1 for default
 309   }
 310   return cell_count;
 311 }
 312 
 313 void MultiBranchData::post_initialize(BytecodeStream* stream,
 314                                       MethodData* mdo) {
 315   assert(stream->bci() == bci(), "wrong pos");
 316   int target;
 317   int my_di;
 318   int target_di;
 319   int offset;
 320   if (stream->code() == Bytecodes::_tableswitch) {
 321     Bytecode_tableswitch sw(stream->method()(), stream->bcp());
 322     int len = sw.length();
 323     assert(array_len() == per_case_cell_count * (len + 1), "wrong len");
 324     for (int count = 0; count < len; count++) {
 325       target = sw.dest_offset_at(count) + bci();
 326       my_di = mdo->dp_to_di(dp());
 327       target_di = mdo->bci_to_di(target);
 328       offset = target_di - my_di;
 329       set_displacement_at(count, offset);
 330     }
 331     target = sw.default_offset() + bci();
 332     my_di = mdo->dp_to_di(dp());
 333     target_di = mdo->bci_to_di(target);
 334     offset = target_di - my_di;
 335     set_default_displacement(offset);
 336 
 337   } else {
 338     Bytecode_lookupswitch sw(stream->method()(), stream->bcp());
 339     int npairs = sw.number_of_pairs();
 340     assert(array_len() == per_case_cell_count * (npairs + 1), "wrong len");
 341     for (int count = 0; count < npairs; count++) {
 342       LookupswitchPair pair = sw.pair_at(count);
 343       target = pair.offset() + bci();
 344       my_di = mdo->dp_to_di(dp());
 345       target_di = mdo->bci_to_di(target);
 346       offset = target_di - my_di;
 347       set_displacement_at(count, offset);
 348     }
 349     target = sw.default_offset() + bci();
 350     my_di = mdo->dp_to_di(dp());
 351     target_di = mdo->bci_to_di(target);
 352     offset = target_di - my_di;
 353     set_default_displacement(offset);
 354   }
 355 }
 356 
 357 #ifndef PRODUCT
 358 void MultiBranchData::print_data_on(outputStream* st) {
 359   print_shared(st, "MultiBranchData");
 360   st->print_cr("default_count(%u) displacement(%d)",
 361                default_count(), default_displacement());
 362   int cases = number_of_cases();
 363   for (int i = 0; i < cases; i++) {
 364     tab(st);
 365     st->print_cr("count(%u) displacement(%d)",
 366                  count_at(i), displacement_at(i));
 367   }
 368 }
 369 #endif
 370 
 371 #ifndef PRODUCT
 372 void ArgInfoData::print_data_on(outputStream* st) {
 373   print_shared(st, "ArgInfoData");
 374   int nargs = number_of_args();
 375   for (int i = 0; i < nargs; i++) {
 376     st->print("  0x%x", arg_modified(i));
 377   }
 378   st->cr();
 379 }
 380 
 381 #endif
 382 // ==================================================================
 383 // MethodData*
 384 //
 385 // A MethodData* holds information which has been collected about
 386 // a method.
 387 
 388 MethodData* MethodData::allocate(ClassLoaderData* loader_data, methodHandle method, TRAPS) {
 389   int size = MethodData::compute_allocation_size_in_words(method);
 390 
 391   return new (loader_data, size, false, THREAD) MethodData(method(), size, CHECK_NULL);
 392 }
 393 
 394 int MethodData::bytecode_cell_count(Bytecodes::Code code) {
 395 #if defined(COMPILER1) && !defined(COMPILER2)
 396   return no_profile_data;
 397 #endif
 398   switch (code) {
 399   case Bytecodes::_checkcast:
 400   case Bytecodes::_instanceof:
 401   case Bytecodes::_aastore:
 402     if (TypeProfileCasts) {
 403       return ReceiverTypeData::static_cell_count();
 404     } else {
 405       return BitData::static_cell_count();
 406     }
 407   case Bytecodes::_invokespecial:
 408   case Bytecodes::_invokestatic:
 409     return CounterData::static_cell_count();
 410   case Bytecodes::_goto:
 411   case Bytecodes::_goto_w:
 412   case Bytecodes::_jsr:
 413   case Bytecodes::_jsr_w:
 414     return JumpData::static_cell_count();
 415   case Bytecodes::_invokevirtual:
 416   case Bytecodes::_invokeinterface:
 417     return VirtualCallData::static_cell_count();
 418   case Bytecodes::_invokedynamic:
 419     return CounterData::static_cell_count();
 420   case Bytecodes::_ret:
 421     return RetData::static_cell_count();
 422   case Bytecodes::_ifeq:
 423   case Bytecodes::_ifne:
 424   case Bytecodes::_iflt:
 425   case Bytecodes::_ifge:
 426   case Bytecodes::_ifgt:
 427   case Bytecodes::_ifle:
 428   case Bytecodes::_if_icmpeq:
 429   case Bytecodes::_if_icmpne:
 430   case Bytecodes::_if_icmplt:
 431   case Bytecodes::_if_icmpge:
 432   case Bytecodes::_if_icmpgt:
 433   case Bytecodes::_if_icmple:
 434   case Bytecodes::_if_acmpeq:
 435   case Bytecodes::_if_acmpne:
 436   case Bytecodes::_ifnull:
 437   case Bytecodes::_ifnonnull:
 438     return BranchData::static_cell_count();
 439   case Bytecodes::_lookupswitch:
 440   case Bytecodes::_tableswitch:
 441     return variable_cell_count;
 442   }
 443   return no_profile_data;
 444 }
 445 
 446 // Compute the size of the profiling information corresponding to
 447 // the current bytecode.
 448 int MethodData::compute_data_size(BytecodeStream* stream) {
 449   int cell_count = bytecode_cell_count(stream->code());
 450   if (cell_count == no_profile_data) {
 451     return 0;
 452   }
 453   if (cell_count == variable_cell_count) {
 454     cell_count = MultiBranchData::compute_cell_count(stream);
 455   }
 456   // Note:  cell_count might be zero, meaning that there is just
 457   //        a DataLayout header, with no extra cells.
 458   assert(cell_count >= 0, "sanity");
 459   return DataLayout::compute_size_in_bytes(cell_count);
 460 }
 461 
 462 int MethodData::compute_extra_data_count(int data_size, int empty_bc_count) {
 463   if (ProfileTraps) {
 464     // Assume that up to 3% of BCIs with no MDP will need to allocate one.
 465     int extra_data_count = (uint)(empty_bc_count * 3) / 128 + 1;
 466     // If the method is large, let the extra BCIs grow numerous (to ~1%).
 467     int one_percent_of_data
 468       = (uint)data_size / (DataLayout::header_size_in_bytes()*128);
 469     if (extra_data_count < one_percent_of_data)
 470       extra_data_count = one_percent_of_data;
 471     if (extra_data_count > empty_bc_count)
 472       extra_data_count = empty_bc_count;  // no need for more
 473     return extra_data_count;
 474   } else {
 475     return 0;
 476   }
 477 }
 478 
 479 // Compute the size of the MethodData* necessary to store
 480 // profiling information about a given method.  Size is in bytes.
 481 int MethodData::compute_allocation_size_in_bytes(methodHandle method) {
 482   int data_size = 0;
 483   BytecodeStream stream(method);
 484   Bytecodes::Code c;
 485   int empty_bc_count = 0;  // number of bytecodes lacking data
 486   while ((c = stream.next()) >= 0) {
 487     int size_in_bytes = compute_data_size(&stream);
 488     data_size += size_in_bytes;
 489     if (size_in_bytes == 0)  empty_bc_count += 1;
 490   }
 491   int object_size = in_bytes(data_offset()) + data_size;
 492 
 493   // Add some extra DataLayout cells (at least one) to track stray traps.
 494   int extra_data_count = compute_extra_data_count(data_size, empty_bc_count);
 495   object_size += extra_data_count * DataLayout::compute_size_in_bytes(0);
 496 
 497   // Add a cell to record information about modified arguments.
 498   int arg_size = method->size_of_parameters();
 499   object_size += DataLayout::compute_size_in_bytes(arg_size+1);
 500   return object_size;
 501 }
 502 
 503 // Compute the size of the MethodData* necessary to store
 504 // profiling information about a given method.  Size is in words
 505 int MethodData::compute_allocation_size_in_words(methodHandle method) {
 506   int byte_size = compute_allocation_size_in_bytes(method);
 507   int word_size = align_size_up(byte_size, BytesPerWord) / BytesPerWord;
 508   return align_object_size(word_size);
 509 }
 510 
 511 // Initialize an individual data segment.  Returns the size of
 512 // the segment in bytes.
 513 int MethodData::initialize_data(BytecodeStream* stream,
 514                                        int data_index) {
 515 #if defined(COMPILER1) && !defined(COMPILER2)
 516   return 0;
 517 #endif
 518   int cell_count = -1;
 519   int tag = DataLayout::no_tag;
 520   DataLayout* data_layout = data_layout_at(data_index);
 521   Bytecodes::Code c = stream->code();
 522   switch (c) {
 523   case Bytecodes::_checkcast:
 524   case Bytecodes::_instanceof:
 525   case Bytecodes::_aastore:
 526     if (TypeProfileCasts) {
 527       cell_count = ReceiverTypeData::static_cell_count();
 528       tag = DataLayout::receiver_type_data_tag;
 529     } else {
 530       cell_count = BitData::static_cell_count();
 531       tag = DataLayout::bit_data_tag;
 532     }
 533     break;
 534   case Bytecodes::_invokespecial:
 535   case Bytecodes::_invokestatic:
 536     cell_count = CounterData::static_cell_count();
 537     tag = DataLayout::counter_data_tag;
 538     break;
 539   case Bytecodes::_goto:
 540   case Bytecodes::_goto_w:
 541   case Bytecodes::_jsr:
 542   case Bytecodes::_jsr_w:
 543     cell_count = JumpData::static_cell_count();
 544     tag = DataLayout::jump_data_tag;
 545     break;
 546   case Bytecodes::_invokevirtual:
 547   case Bytecodes::_invokeinterface:
 548     cell_count = VirtualCallData::static_cell_count();
 549     tag = DataLayout::virtual_call_data_tag;
 550     break;
 551   case Bytecodes::_invokedynamic:
 552     // %%% should make a type profile for any invokedynamic that takes a ref argument
 553     cell_count = CounterData::static_cell_count();
 554     tag = DataLayout::counter_data_tag;
 555     break;
 556   case Bytecodes::_ret:
 557     cell_count = RetData::static_cell_count();
 558     tag = DataLayout::ret_data_tag;
 559     break;
 560   case Bytecodes::_ifeq:
 561   case Bytecodes::_ifne:
 562   case Bytecodes::_iflt:
 563   case Bytecodes::_ifge:
 564   case Bytecodes::_ifgt:
 565   case Bytecodes::_ifle:
 566   case Bytecodes::_if_icmpeq:
 567   case Bytecodes::_if_icmpne:
 568   case Bytecodes::_if_icmplt:
 569   case Bytecodes::_if_icmpge:
 570   case Bytecodes::_if_icmpgt:
 571   case Bytecodes::_if_icmple:
 572   case Bytecodes::_if_acmpeq:
 573   case Bytecodes::_if_acmpne:
 574   case Bytecodes::_ifnull:
 575   case Bytecodes::_ifnonnull:
 576     cell_count = BranchData::static_cell_count();
 577     tag = DataLayout::branch_data_tag;
 578     break;
 579   case Bytecodes::_lookupswitch:
 580   case Bytecodes::_tableswitch:
 581     cell_count = MultiBranchData::compute_cell_count(stream);
 582     tag = DataLayout::multi_branch_data_tag;
 583     break;
 584   }
 585   assert(tag == DataLayout::multi_branch_data_tag ||
 586          cell_count == bytecode_cell_count(c), "cell counts must agree");
 587   if (cell_count >= 0) {
 588     assert(tag != DataLayout::no_tag, "bad tag");
 589     assert(bytecode_has_profile(c), "agree w/ BHP");
 590     data_layout->initialize(tag, stream->bci(), cell_count);
 591     return DataLayout::compute_size_in_bytes(cell_count);
 592   } else {
 593     assert(!bytecode_has_profile(c), "agree w/ !BHP");
 594     return 0;
 595   }
 596 }
 597 
 598 // Get the data at an arbitrary (sort of) data index.
 599 ProfileData* MethodData::data_at(int data_index) const {
 600   if (out_of_bounds(data_index)) {
 601     return NULL;
 602   }
 603   DataLayout* data_layout = data_layout_at(data_index);
 604   return data_layout->data_in();
 605 }
 606 
 607 ProfileData* DataLayout::data_in() {
 608   switch (tag()) {
 609   case DataLayout::no_tag:
 610   default:
 611     ShouldNotReachHere();
 612     return NULL;
 613   case DataLayout::bit_data_tag:
 614     return new BitData(this);
 615   case DataLayout::counter_data_tag:
 616     return new CounterData(this);
 617   case DataLayout::jump_data_tag:
 618     return new JumpData(this);
 619   case DataLayout::receiver_type_data_tag:
 620     return new ReceiverTypeData(this);
 621   case DataLayout::virtual_call_data_tag:
 622     return new VirtualCallData(this);
 623   case DataLayout::ret_data_tag:
 624     return new RetData(this);
 625   case DataLayout::branch_data_tag:
 626     return new BranchData(this);
 627   case DataLayout::multi_branch_data_tag:
 628     return new MultiBranchData(this);
 629   case DataLayout::arg_info_data_tag:
 630     return new ArgInfoData(this);
 631   };
 632 }
 633 
 634 // Iteration over data.
 635 ProfileData* MethodData::next_data(ProfileData* current) const {
 636   int current_index = dp_to_di(current->dp());
 637   int next_index = current_index + current->size_in_bytes();
 638   ProfileData* next = data_at(next_index);
 639   return next;
 640 }
 641 
 642 // Give each of the data entries a chance to perform specific
 643 // data initialization.
 644 void MethodData::post_initialize(BytecodeStream* stream) {
 645   ResourceMark rm;
 646   ProfileData* data;
 647   for (data = first_data(); is_valid(data); data = next_data(data)) {
 648     stream->set_start(data->bci());
 649     stream->next();
 650     data->post_initialize(stream, this);
 651   }
 652 }
 653 
 654 // Initialize the MethodData* corresponding to a given method.
 655 MethodData::MethodData(methodHandle method, int size, TRAPS) {
 656   No_Safepoint_Verifier no_safepoint;  // init function atomic wrt GC
 657   ResourceMark rm;
 658   // Set the method back-pointer.
 659   _method = method();
 660 
 661   if (TieredCompilation) {
 662     _invocation_counter.init();
 663     _backedge_counter.init();
 664     _invocation_counter_start = 0;
 665     _backedge_counter_start = 0;
 666     _num_loops = 0;
 667     _num_blocks = 0;
 668     _highest_comp_level = 0;
 669     _highest_osr_comp_level = 0;
 670     _would_profile = true;
 671   }
 672   set_creation_mileage(mileage_of(method()));
 673 
 674   // Initialize flags and trap history.
 675   _nof_decompiles = 0;
 676   _nof_overflow_recompiles = 0;
 677   _nof_overflow_traps = 0;
 678   assert(sizeof(_trap_hist) % sizeof(HeapWord) == 0, "align");
 679   Copy::zero_to_words((HeapWord*) &_trap_hist,
 680                       sizeof(_trap_hist) / sizeof(HeapWord));
 681 
 682   // Go through the bytecodes and allocate and initialize the
 683   // corresponding data cells.
 684   int data_size = 0;
 685   int empty_bc_count = 0;  // number of bytecodes lacking data
 686   BytecodeStream stream(method);
 687   Bytecodes::Code c;
 688   while ((c = stream.next()) >= 0) {
 689     int size_in_bytes = initialize_data(&stream, data_size);
 690     data_size += size_in_bytes;
 691     if (size_in_bytes == 0)  empty_bc_count += 1;
 692   }
 693   _data_size = data_size;
 694   int object_size = in_bytes(data_offset()) + data_size;
 695 
 696   // Add some extra DataLayout cells (at least one) to track stray traps.
 697   int extra_data_count = compute_extra_data_count(data_size, empty_bc_count);
 698   int extra_size = extra_data_count * DataLayout::compute_size_in_bytes(0);
 699 
 700   // Add a cell to record information about modified arguments.
 701   // Set up _args_modified array after traps cells so that
 702   // the code for traps cells works.
 703   DataLayout *dp = data_layout_at(data_size + extra_size);
 704 
 705   int arg_size = method->size_of_parameters();
 706   dp->initialize(DataLayout::arg_info_data_tag, 0, arg_size+1);
 707 
 708   object_size += extra_size + DataLayout::compute_size_in_bytes(arg_size+1);
 709 
 710   // Set an initial hint. Don't use set_hint_di() because
 711   // first_di() may be out of bounds if data_size is 0.
 712   // In that situation, _hint_di is never used, but at
 713   // least well-defined.
 714   _hint_di = first_di();
 715 
 716   post_initialize(&stream);
 717 
 718   set_size(object_size);
 719 }
 720 
 721 // Get a measure of how much mileage the method has on it.
 722 int MethodData::mileage_of(Method* method) {
 723   int mileage = 0;
 724   if (TieredCompilation) {
 725     mileage = MAX2(method->invocation_count(), method->backedge_count());
 726   } else {
 727     int iic = method->interpreter_invocation_count();
 728     if (mileage < iic)  mileage = iic;
 729     InvocationCounter* ic = method->invocation_counter();
 730     InvocationCounter* bc = method->backedge_counter();
 731     int icval = ic->count();
 732     if (ic->carry()) icval += CompileThreshold;
 733     if (mileage < icval)  mileage = icval;
 734     int bcval = bc->count();
 735     if (bc->carry()) bcval += CompileThreshold;
 736     if (mileage < bcval)  mileage = bcval;
 737   }
 738   return mileage;
 739 }
 740 
 741 bool MethodData::is_mature() const {
 742   return CompilationPolicy::policy()->is_mature(_method);
 743 }
 744 
 745 // Translate a bci to its corresponding data index (di).
 746 address MethodData::bci_to_dp(int bci) {
 747   ResourceMark rm;
 748   ProfileData* data = data_before(bci);
 749   ProfileData* prev = NULL;
 750   for ( ; is_valid(data); data = next_data(data)) {
 751     if (data->bci() >= bci) {
 752       if (data->bci() == bci)  set_hint_di(dp_to_di(data->dp()));
 753       else if (prev != NULL)   set_hint_di(dp_to_di(prev->dp()));
 754       return data->dp();
 755     }
 756     prev = data;
 757   }
 758   return (address)limit_data_position();
 759 }
 760 
 761 // Translate a bci to its corresponding data, or NULL.
 762 ProfileData* MethodData::bci_to_data(int bci) {
 763   ProfileData* data = data_before(bci);
 764   for ( ; is_valid(data); data = next_data(data)) {
 765     if (data->bci() == bci) {
 766       set_hint_di(dp_to_di(data->dp()));
 767       return data;
 768     } else if (data->bci() > bci) {
 769       break;
 770     }
 771   }
 772   return bci_to_extra_data(bci, false);
 773 }
 774 
 775 // Translate a bci to its corresponding extra data, or NULL.
 776 ProfileData* MethodData::bci_to_extra_data(int bci, bool create_if_missing) {
 777   DataLayout* dp    = extra_data_base();
 778   DataLayout* end   = extra_data_limit();
 779   DataLayout* avail = NULL;
 780   for (; dp < end; dp = next_extra(dp)) {
 781     // No need for "OrderAccess::load_acquire" ops,
 782     // since the data structure is monotonic.
 783     if (dp->tag() == DataLayout::no_tag)  break;
 784     if (dp->tag() == DataLayout::arg_info_data_tag) {
 785       dp = end; // ArgInfoData is at the end of extra data section.
 786       break;
 787     }
 788     if (dp->bci() == bci) {
 789       assert(dp->tag() == DataLayout::bit_data_tag, "sane");
 790       return new BitData(dp);
 791     }
 792   }
 793   if (create_if_missing && dp < end) {
 794     // Allocate this one.  There is no mutual exclusion,
 795     // so two threads could allocate different BCIs to the
 796     // same data layout.  This means these extra data
 797     // records, like most other MDO contents, must not be
 798     // trusted too much.
 799     DataLayout temp;
 800     temp.initialize(DataLayout::bit_data_tag, bci, 0);
 801     dp->release_set_header(temp.header());
 802     assert(dp->tag() == DataLayout::bit_data_tag, "sane");
 803     //NO: assert(dp->bci() == bci, "no concurrent allocation");
 804     return new BitData(dp);
 805   }
 806   return NULL;
 807 }
 808 
 809 ArgInfoData *MethodData::arg_info() {
 810   DataLayout* dp    = extra_data_base();
 811   DataLayout* end   = extra_data_limit();
 812   for (; dp < end; dp = next_extra(dp)) {
 813     if (dp->tag() == DataLayout::arg_info_data_tag)
 814       return new ArgInfoData(dp);
 815   }
 816   return NULL;
 817 }
 818 
 819 // Printing
 820 
 821 #ifndef PRODUCT
 822 
 823 void MethodData::print_on(outputStream* st) const {
 824   assert(is_methodData(), "should be method data");
 825   st->print("method data for ");
 826   method()->print_value_on(st);
 827   st->cr();
 828   print_data_on(st);
 829 }
 830 
 831 #endif //PRODUCT
 832 
 833 void MethodData::print_value_on(outputStream* st) const {
 834   assert(is_methodData(), "should be method data");
 835   st->print("method data for ");
 836   method()->print_value_on(st);
 837 }
 838 
 839 #ifndef PRODUCT
 840 void MethodData::print_data_on(outputStream* st) const {
 841   ResourceMark rm;
 842   ProfileData* data = first_data();
 843   for ( ; is_valid(data); data = next_data(data)) {
 844     st->print("%d", dp_to_di(data->dp()));
 845     st->fill_to(6);
 846     data->print_data_on(st);
 847   }
 848   st->print_cr("--- Extra data:");
 849   DataLayout* dp    = extra_data_base();
 850   DataLayout* end   = extra_data_limit();
 851   for (; dp < end; dp = next_extra(dp)) {
 852     // No need for "OrderAccess::load_acquire" ops,
 853     // since the data structure is monotonic.
 854     if (dp->tag() == DataLayout::no_tag)  continue;
 855     if (dp->tag() == DataLayout::bit_data_tag) {
 856       data = new BitData(dp);
 857     } else {
 858       assert(dp->tag() == DataLayout::arg_info_data_tag, "must be BitData or ArgInfo");
 859       data = new ArgInfoData(dp);
 860       dp = end; // ArgInfoData is at the end of extra data section.
 861     }
 862     st->print("%d", dp_to_di(data->dp()));
 863     st->fill_to(6);
 864     data->print_data_on(st);
 865   }
 866 }
 867 #endif
 868 
 869 #if INCLUDE_SERVICES
 870 // Size Statistics
 871 void MethodData::collect_statistics(KlassSizeStats *sz) const {
 872   int n = sz->count(this);
 873   sz->_method_data_bytes += n;
 874   sz->_method_all_bytes += n;
 875   sz->_rw_bytes += n;
 876 }
 877 #endif // INCLUDE_SERVICES
 878 
 879 // Verification
 880 
 881 void MethodData::verify_on(outputStream* st) {
 882   guarantee(is_methodData(), "object must be method data");
 883   // guarantee(m->is_perm(), "should be in permspace");
 884   this->verify_data_on(st);
 885 }
 886 
 887 void MethodData::verify_data_on(outputStream* st) {
 888   NEEDS_CLEANUP;
 889   // not yet implemented.
 890 }