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 "ci/ciConstant.hpp"
  27 #include "ci/ciField.hpp"
  28 #include "ci/ciMethod.hpp"
  29 #include "ci/ciMethodData.hpp"
  30 #include "ci/ciObjArrayKlass.hpp"
  31 #include "ci/ciStreams.hpp"
  32 #include "ci/ciTypeArrayKlass.hpp"
  33 #include "ci/ciTypeFlow.hpp"
  34 #include "compiler/compileLog.hpp"
  35 #include "interpreter/bytecode.hpp"
  36 #include "interpreter/bytecodes.hpp"
  37 #include "memory/allocation.inline.hpp"
  38 #include "runtime/deoptimization.hpp"
  39 #include "utilities/growableArray.hpp"
  40 
  41 // ciTypeFlow::JsrSet
  42 //
  43 // A JsrSet represents some set of JsrRecords.  This class
  44 // is used to record a set of all jsr routines which we permit
  45 // execution to return (ret) from.
  46 //
  47 // During abstract interpretation, JsrSets are used to determine
  48 // whether two paths which reach a given block are unique, and
  49 // should be cloned apart, or are compatible, and should merge
  50 // together.
  51 
  52 // ------------------------------------------------------------------
  53 // ciTypeFlow::JsrSet::JsrSet
  54 ciTypeFlow::JsrSet::JsrSet(Arena* arena, int default_len) {
  55   if (arena != NULL) {
  56     // Allocate growable array in Arena.
  57     _set = new (arena) GrowableArray<JsrRecord*>(arena, default_len, 0, NULL);
  58   } else {
  59     // Allocate growable array in current ResourceArea.
  60     _set = new GrowableArray<JsrRecord*>(4, 0, NULL, false);
  61   }
  62 }
  63 
  64 // ------------------------------------------------------------------
  65 // ciTypeFlow::JsrSet::copy_into
  66 void ciTypeFlow::JsrSet::copy_into(JsrSet* jsrs) {
  67   int len = size();
  68   jsrs->_set->clear();
  69   for (int i = 0; i < len; i++) {
  70     jsrs->_set->append(_set->at(i));
  71   }
  72 }
  73 
  74 // ------------------------------------------------------------------
  75 // ciTypeFlow::JsrSet::is_compatible_with
  76 //
  77 // !!!! MISGIVINGS ABOUT THIS... disregard
  78 //
  79 // Is this JsrSet compatible with some other JsrSet?
  80 //
  81 // In set-theoretic terms, a JsrSet can be viewed as a partial function
  82 // from entry addresses to return addresses.  Two JsrSets A and B are
  83 // compatible iff
  84 //
  85 //   For any x,
  86 //   A(x) defined and B(x) defined implies A(x) == B(x)
  87 //
  88 // Less formally, two JsrSets are compatible when they have identical
  89 // return addresses for any entry addresses they share in common.
  90 bool ciTypeFlow::JsrSet::is_compatible_with(JsrSet* other) {
  91   // Walk through both sets in parallel.  If the same entry address
  92   // appears in both sets, then the return address must match for
  93   // the sets to be compatible.
  94   int size1 = size();
  95   int size2 = other->size();
  96 
  97   // Special case.  If nothing is on the jsr stack, then there can
  98   // be no ret.
  99   if (size2 == 0) {
 100     return true;
 101   } else if (size1 != size2) {
 102     return false;
 103   } else {
 104     for (int i = 0; i < size1; i++) {
 105       JsrRecord* record1 = record_at(i);
 106       JsrRecord* record2 = other->record_at(i);
 107       if (record1->entry_address() != record2->entry_address() ||
 108           record1->return_address() != record2->return_address()) {
 109         return false;
 110       }
 111     }
 112     return true;
 113   }
 114 
 115 #if 0
 116   int pos1 = 0;
 117   int pos2 = 0;
 118   int size1 = size();
 119   int size2 = other->size();
 120   while (pos1 < size1 && pos2 < size2) {
 121     JsrRecord* record1 = record_at(pos1);
 122     JsrRecord* record2 = other->record_at(pos2);
 123     int entry1 = record1->entry_address();
 124     int entry2 = record2->entry_address();
 125     if (entry1 < entry2) {
 126       pos1++;
 127     } else if (entry1 > entry2) {
 128       pos2++;
 129     } else {
 130       if (record1->return_address() == record2->return_address()) {
 131         pos1++;
 132         pos2++;
 133       } else {
 134         // These two JsrSets are incompatible.
 135         return false;
 136       }
 137     }
 138   }
 139   // The two JsrSets agree.
 140   return true;
 141 #endif
 142 }
 143 
 144 // ------------------------------------------------------------------
 145 // ciTypeFlow::JsrSet::insert_jsr_record
 146 //
 147 // Insert the given JsrRecord into the JsrSet, maintaining the order
 148 // of the set and replacing any element with the same entry address.
 149 void ciTypeFlow::JsrSet::insert_jsr_record(JsrRecord* record) {
 150   int len = size();
 151   int entry = record->entry_address();
 152   int pos = 0;
 153   for ( ; pos < len; pos++) {
 154     JsrRecord* current = record_at(pos);
 155     if (entry == current->entry_address()) {
 156       // Stomp over this entry.
 157       _set->at_put(pos, record);
 158       assert(size() == len, "must be same size");
 159       return;
 160     } else if (entry < current->entry_address()) {
 161       break;
 162     }
 163   }
 164 
 165   // Insert the record into the list.
 166   JsrRecord* swap = record;
 167   JsrRecord* temp = NULL;
 168   for ( ; pos < len; pos++) {
 169     temp = _set->at(pos);
 170     _set->at_put(pos, swap);
 171     swap = temp;
 172   }
 173   _set->append(swap);
 174   assert(size() == len+1, "must be larger");
 175 }
 176 
 177 // ------------------------------------------------------------------
 178 // ciTypeFlow::JsrSet::remove_jsr_record
 179 //
 180 // Remove the JsrRecord with the given return address from the JsrSet.
 181 void ciTypeFlow::JsrSet::remove_jsr_record(int return_address) {
 182   int len = size();
 183   for (int i = 0; i < len; i++) {
 184     if (record_at(i)->return_address() == return_address) {
 185       // We have found the proper entry.  Remove it from the
 186       // JsrSet and exit.
 187       for (int j = i+1; j < len ; j++) {
 188         _set->at_put(j-1, _set->at(j));
 189       }
 190       _set->trunc_to(len-1);
 191       assert(size() == len-1, "must be smaller");
 192       return;
 193     }
 194   }
 195   assert(false, "verify: returning from invalid subroutine");
 196 }
 197 
 198 // ------------------------------------------------------------------
 199 // ciTypeFlow::JsrSet::apply_control
 200 //
 201 // Apply the effect of a control-flow bytecode on the JsrSet.  The
 202 // only bytecodes that modify the JsrSet are jsr and ret.
 203 void ciTypeFlow::JsrSet::apply_control(ciTypeFlow* analyzer,
 204                                        ciBytecodeStream* str,
 205                                        ciTypeFlow::StateVector* state) {
 206   Bytecodes::Code code = str->cur_bc();
 207   if (code == Bytecodes::_jsr) {
 208     JsrRecord* record =
 209       analyzer->make_jsr_record(str->get_dest(), str->next_bci());
 210     insert_jsr_record(record);
 211   } else if (code == Bytecodes::_jsr_w) {
 212     JsrRecord* record =
 213       analyzer->make_jsr_record(str->get_far_dest(), str->next_bci());
 214     insert_jsr_record(record);
 215   } else if (code == Bytecodes::_ret) {
 216     Cell local = state->local(str->get_index());
 217     ciType* return_address = state->type_at(local);
 218     assert(return_address->is_return_address(), "verify: wrong type");
 219     if (size() == 0) {
 220       // Ret-state underflow:  Hit a ret w/o any previous jsrs.  Bail out.
 221       // This can happen when a loop is inside a finally clause (4614060).
 222       analyzer->record_failure("OSR in finally clause");
 223       return;
 224     }
 225     remove_jsr_record(return_address->as_return_address()->bci());
 226   }
 227 }
 228 
 229 #ifndef PRODUCT
 230 // ------------------------------------------------------------------
 231 // ciTypeFlow::JsrSet::print_on
 232 void ciTypeFlow::JsrSet::print_on(outputStream* st) const {
 233   st->print("{ ");
 234   int num_elements = size();
 235   if (num_elements > 0) {
 236     int i = 0;
 237     for( ; i < num_elements - 1; i++) {
 238       _set->at(i)->print_on(st);
 239       st->print(", ");
 240     }
 241     _set->at(i)->print_on(st);
 242     st->print(" ");
 243   }
 244   st->print("}");
 245 }
 246 #endif
 247 
 248 // ciTypeFlow::StateVector
 249 //
 250 // A StateVector summarizes the type information at some point in
 251 // the program.
 252 
 253 // ------------------------------------------------------------------
 254 // ciTypeFlow::StateVector::type_meet
 255 //
 256 // Meet two types.
 257 //
 258 // The semi-lattice of types use by this analysis are modeled on those
 259 // of the verifier.  The lattice is as follows:
 260 //
 261 //        top_type() >= all non-extremal types >= bottom_type
 262 //                             and
 263 //   Every primitive type is comparable only with itself.  The meet of
 264 //   reference types is determined by their kind: instance class,
 265 //   interface, or array class.  The meet of two types of the same
 266 //   kind is their least common ancestor.  The meet of two types of
 267 //   different kinds is always java.lang.Object.
 268 ciType* ciTypeFlow::StateVector::type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer) {
 269   assert(t1 != t2, "checked in caller");
 270   if (t1->equals(top_type())) {
 271     return t2;
 272   } else if (t2->equals(top_type())) {
 273     return t1;
 274   } else if (t1->is_primitive_type() || t2->is_primitive_type()) {
 275     // Special case null_type.  null_type meet any reference type T
 276     // is T.  null_type meet null_type is null_type.
 277     if (t1->equals(null_type())) {
 278       if (!t2->is_primitive_type() || t2->equals(null_type())) {
 279         return t2;
 280       }
 281     } else if (t2->equals(null_type())) {
 282       if (!t1->is_primitive_type()) {
 283         return t1;
 284       }
 285     }
 286 
 287     // At least one of the two types is a non-top primitive type.
 288     // The other type is not equal to it.  Fall to bottom.
 289     return bottom_type();
 290   } else {
 291     // Both types are non-top non-primitive types.  That is,
 292     // both types are either instanceKlasses or arrayKlasses.
 293     ciKlass* object_klass = analyzer->env()->Object_klass();
 294     ciKlass* k1 = t1->as_klass();
 295     ciKlass* k2 = t2->as_klass();
 296     if (k1->equals(object_klass) || k2->equals(object_klass)) {
 297       return object_klass;
 298     } else if (!k1->is_loaded() || !k2->is_loaded()) {
 299       // Unloaded classes fall to java.lang.Object at a merge.
 300       return object_klass;
 301     } else if (k1->is_interface() != k2->is_interface()) {
 302       // When an interface meets a non-interface, we get Object;
 303       // This is what the verifier does.
 304       return object_klass;
 305     } else if (k1->is_array_klass() || k2->is_array_klass()) {
 306       // When an array meets a non-array, we get Object.
 307       // When objArray meets typeArray, we also get Object.
 308       // And when typeArray meets different typeArray, we again get Object.
 309       // But when objArray meets objArray, we look carefully at element types.
 310       if (k1->is_obj_array_klass() && k2->is_obj_array_klass()) {
 311         // Meet the element types, then construct the corresponding array type.
 312         ciKlass* elem1 = k1->as_obj_array_klass()->element_klass();
 313         ciKlass* elem2 = k2->as_obj_array_klass()->element_klass();
 314         ciKlass* elem  = type_meet_internal(elem1, elem2, analyzer)->as_klass();
 315         // Do an easy shortcut if one type is a super of the other.
 316         if (elem == elem1) {
 317           assert(k1 == ciObjArrayKlass::make(elem), "shortcut is OK");
 318           return k1;
 319         } else if (elem == elem2) {
 320           assert(k2 == ciObjArrayKlass::make(elem), "shortcut is OK");
 321           return k2;
 322         } else {
 323           return ciObjArrayKlass::make(elem);
 324         }
 325       } else {
 326         return object_klass;
 327       }
 328     } else {
 329       // Must be two plain old instance klasses.
 330       assert(k1->is_instance_klass(), "previous cases handle non-instances");
 331       assert(k2->is_instance_klass(), "previous cases handle non-instances");
 332       return k1->least_common_ancestor(k2);
 333     }
 334   }
 335 }
 336 
 337 
 338 // ------------------------------------------------------------------
 339 // ciTypeFlow::StateVector::StateVector
 340 //
 341 // Build a new state vector
 342 ciTypeFlow::StateVector::StateVector(ciTypeFlow* analyzer) {
 343   _outer = analyzer;
 344   _stack_size = -1;
 345   _monitor_count = -1;
 346   // Allocate the _types array
 347   int max_cells = analyzer->max_cells();
 348   _types = (ciType**)analyzer->arena()->Amalloc(sizeof(ciType*) * max_cells);
 349   for (int i=0; i<max_cells; i++) {
 350     _types[i] = top_type();
 351   }
 352   _trap_bci = -1;
 353   _trap_index = 0;
 354   _def_locals.clear();
 355 }
 356 
 357 
 358 // ------------------------------------------------------------------
 359 // ciTypeFlow::get_start_state
 360 //
 361 // Set this vector to the method entry state.
 362 const ciTypeFlow::StateVector* ciTypeFlow::get_start_state() {
 363   StateVector* state = new StateVector(this);
 364   if (is_osr_flow()) {
 365     ciTypeFlow* non_osr_flow = method()->get_flow_analysis();
 366     if (non_osr_flow->failing()) {
 367       record_failure(non_osr_flow->failure_reason());
 368       return NULL;
 369     }
 370     JsrSet* jsrs = new JsrSet(NULL, 16);
 371     Block* non_osr_block = non_osr_flow->existing_block_at(start_bci(), jsrs);
 372     if (non_osr_block == NULL) {
 373       record_failure("cannot reach OSR point");
 374       return NULL;
 375     }
 376     // load up the non-OSR state at this point
 377     non_osr_block->copy_state_into(state);
 378     int non_osr_start = non_osr_block->start();
 379     if (non_osr_start != start_bci()) {
 380       // must flow forward from it
 381       if (CITraceTypeFlow) {
 382         tty->print_cr(">> Interpreting pre-OSR block %d:", non_osr_start);
 383       }
 384       Block* block = block_at(non_osr_start, jsrs);
 385       assert(block->limit() == start_bci(), "must flow forward to start");
 386       flow_block(block, state, jsrs);
 387     }
 388     return state;
 389     // Note:  The code below would be an incorrect for an OSR flow,
 390     // even if it were possible for an OSR entry point to be at bci zero.
 391   }
 392   // "Push" the method signature into the first few locals.
 393   state->set_stack_size(-max_locals());
 394   if (!method()->is_static()) {
 395     state->push(method()->holder());
 396     assert(state->tos() == state->local(0), "");
 397   }
 398   for (ciSignatureStream str(method()->signature());
 399        !str.at_return_type();
 400        str.next()) {
 401     state->push_translate(str.type());
 402   }
 403   // Set the rest of the locals to bottom.
 404   Cell cell = state->next_cell(state->tos());
 405   state->set_stack_size(0);
 406   int limit = state->limit_cell();
 407   for (; cell < limit; cell = state->next_cell(cell)) {
 408     state->set_type_at(cell, state->bottom_type());
 409   }
 410   // Lock an object, if necessary.
 411   state->set_monitor_count(method()->is_synchronized() ? 1 : 0);
 412   return state;
 413 }
 414 
 415 // ------------------------------------------------------------------
 416 // ciTypeFlow::StateVector::copy_into
 417 //
 418 // Copy our value into some other StateVector
 419 void ciTypeFlow::StateVector::copy_into(ciTypeFlow::StateVector* copy)
 420 const {
 421   copy->set_stack_size(stack_size());
 422   copy->set_monitor_count(monitor_count());
 423   Cell limit = limit_cell();
 424   for (Cell c = start_cell(); c < limit; c = next_cell(c)) {
 425     copy->set_type_at(c, type_at(c));
 426   }
 427 }
 428 
 429 // ------------------------------------------------------------------
 430 // ciTypeFlow::StateVector::meet
 431 //
 432 // Meets this StateVector with another, destructively modifying this
 433 // one.  Returns true if any modification takes place.
 434 bool ciTypeFlow::StateVector::meet(const ciTypeFlow::StateVector* incoming) {
 435   if (monitor_count() == -1) {
 436     set_monitor_count(incoming->monitor_count());
 437   }
 438   assert(monitor_count() == incoming->monitor_count(), "monitors must match");
 439 
 440   if (stack_size() == -1) {
 441     set_stack_size(incoming->stack_size());
 442     Cell limit = limit_cell();
 443     #ifdef ASSERT
 444     { for (Cell c = start_cell(); c < limit; c = next_cell(c)) {
 445         assert(type_at(c) == top_type(), "");
 446     } }
 447     #endif
 448     // Make a simple copy of the incoming state.
 449     for (Cell c = start_cell(); c < limit; c = next_cell(c)) {
 450       set_type_at(c, incoming->type_at(c));
 451     }
 452     return true;  // it is always different the first time
 453   }
 454 #ifdef ASSERT
 455   if (stack_size() != incoming->stack_size()) {
 456     _outer->method()->print_codes();
 457     tty->print_cr("!!!! Stack size conflict");
 458     tty->print_cr("Current state:");
 459     print_on(tty);
 460     tty->print_cr("Incoming state:");
 461     ((StateVector*)incoming)->print_on(tty);
 462   }
 463 #endif
 464   assert(stack_size() == incoming->stack_size(), "sanity");
 465 
 466   bool different = false;
 467   Cell limit = limit_cell();
 468   for (Cell c = start_cell(); c < limit; c = next_cell(c)) {
 469     ciType* t1 = type_at(c);
 470     ciType* t2 = incoming->type_at(c);
 471     if (!t1->equals(t2)) {
 472       ciType* new_type = type_meet(t1, t2);
 473       if (!t1->equals(new_type)) {
 474         set_type_at(c, new_type);
 475         different = true;
 476       }
 477     }
 478   }
 479   return different;
 480 }
 481 
 482 // ------------------------------------------------------------------
 483 // ciTypeFlow::StateVector::meet_exception
 484 //
 485 // Meets this StateVector with another, destructively modifying this
 486 // one.  The incoming state is coming via an exception.  Returns true
 487 // if any modification takes place.
 488 bool ciTypeFlow::StateVector::meet_exception(ciInstanceKlass* exc,
 489                                      const ciTypeFlow::StateVector* incoming) {
 490   if (monitor_count() == -1) {
 491     set_monitor_count(incoming->monitor_count());
 492   }
 493   assert(monitor_count() == incoming->monitor_count(), "monitors must match");
 494 
 495   if (stack_size() == -1) {
 496     set_stack_size(1);
 497   }
 498 
 499   assert(stack_size() ==  1, "must have one-element stack");
 500 
 501   bool different = false;
 502 
 503   // Meet locals from incoming array.
 504   Cell limit = local(_outer->max_locals()-1);
 505   for (Cell c = start_cell(); c <= limit; c = next_cell(c)) {
 506     ciType* t1 = type_at(c);
 507     ciType* t2 = incoming->type_at(c);
 508     if (!t1->equals(t2)) {
 509       ciType* new_type = type_meet(t1, t2);
 510       if (!t1->equals(new_type)) {
 511         set_type_at(c, new_type);
 512         different = true;
 513       }
 514     }
 515   }
 516 
 517   // Handle stack separately.  When an exception occurs, the
 518   // only stack entry is the exception instance.
 519   ciType* tos_type = type_at_tos();
 520   if (!tos_type->equals(exc)) {
 521     ciType* new_type = type_meet(tos_type, exc);
 522     if (!tos_type->equals(new_type)) {
 523       set_type_at_tos(new_type);
 524       different = true;
 525     }
 526   }
 527 
 528   return different;
 529 }
 530 
 531 // ------------------------------------------------------------------
 532 // ciTypeFlow::StateVector::push_translate
 533 void ciTypeFlow::StateVector::push_translate(ciType* type) {
 534   BasicType basic_type = type->basic_type();
 535   if (basic_type == T_BOOLEAN || basic_type == T_CHAR ||
 536       basic_type == T_BYTE    || basic_type == T_SHORT) {
 537     push_int();
 538   } else {
 539     push(type);
 540     if (type->is_two_word()) {
 541       push(half_type(type));
 542     }
 543   }
 544 }
 545 
 546 // ------------------------------------------------------------------
 547 // ciTypeFlow::StateVector::do_aaload
 548 void ciTypeFlow::StateVector::do_aaload(ciBytecodeStream* str) {
 549   pop_int();
 550   ciObjArrayKlass* array_klass = pop_objArray();
 551   if (array_klass == NULL) {
 552     // Did aaload on a null reference; push a null and ignore the exception.
 553     // This instruction will never continue normally.  All we have to do
 554     // is report a value that will meet correctly with any downstream
 555     // reference types on paths that will truly be executed.  This null type
 556     // meets with any reference type to yield that same reference type.
 557     // (The compiler will generate an unconditional exception here.)
 558     push(null_type());
 559     return;
 560   }
 561   if (!array_klass->is_loaded()) {
 562     // Only fails for some -Xcomp runs
 563     trap(str, array_klass,
 564          Deoptimization::make_trap_request
 565          (Deoptimization::Reason_unloaded,
 566           Deoptimization::Action_reinterpret));
 567     return;
 568   }
 569   ciKlass* element_klass = array_klass->element_klass();
 570   if (!element_klass->is_loaded() && element_klass->is_instance_klass()) {
 571     Untested("unloaded array element class in ciTypeFlow");
 572     trap(str, element_klass,
 573          Deoptimization::make_trap_request
 574          (Deoptimization::Reason_unloaded,
 575           Deoptimization::Action_reinterpret));
 576   } else {
 577     push_object(element_klass);
 578   }
 579 }
 580 
 581 
 582 // ------------------------------------------------------------------
 583 // ciTypeFlow::StateVector::do_checkcast
 584 void ciTypeFlow::StateVector::do_checkcast(ciBytecodeStream* str) {
 585   bool will_link;
 586   ciKlass* klass = str->get_klass(will_link);
 587   if (!will_link) {
 588     // VM's interpreter will not load 'klass' if object is NULL.
 589     // Type flow after this block may still be needed in two situations:
 590     // 1) C2 uses do_null_assert() and continues compilation for later blocks
 591     // 2) C2 does an OSR compile in a later block (see bug 4778368).
 592     pop_object();
 593     do_null_assert(klass);
 594   } else {
 595     pop_object();
 596     push_object(klass);
 597   }
 598 }
 599 
 600 // ------------------------------------------------------------------
 601 // ciTypeFlow::StateVector::do_getfield
 602 void ciTypeFlow::StateVector::do_getfield(ciBytecodeStream* str) {
 603   // could add assert here for type of object.
 604   pop_object();
 605   do_getstatic(str);
 606 }
 607 
 608 // ------------------------------------------------------------------
 609 // ciTypeFlow::StateVector::do_getstatic
 610 void ciTypeFlow::StateVector::do_getstatic(ciBytecodeStream* str) {
 611   bool will_link;
 612   ciField* field = str->get_field(will_link);
 613   if (!will_link) {
 614     trap(str, field->holder(), str->get_field_holder_index());
 615   } else {
 616     ciType* field_type = field->type();
 617     if (!field_type->is_loaded()) {
 618       // Normally, we need the field's type to be loaded if we are to
 619       // do anything interesting with its value.
 620       // We used to do this:  trap(str, str->get_field_signature_index());
 621       //
 622       // There is one good reason not to trap here.  Execution can
 623       // get past this "getfield" or "getstatic" if the value of
 624       // the field is null.  As long as the value is null, the class
 625       // does not need to be loaded!  The compiler must assume that
 626       // the value of the unloaded class reference is null; if the code
 627       // ever sees a non-null value, loading has occurred.
 628       //
 629       // This actually happens often enough to be annoying.  If the
 630       // compiler throws an uncommon trap at this bytecode, you can
 631       // get an endless loop of recompilations, when all the code
 632       // needs to do is load a series of null values.  Also, a trap
 633       // here can make an OSR entry point unreachable, triggering the
 634       // assert on non_osr_block in ciTypeFlow::get_start_state.
 635       // (See bug 4379915.)
 636       do_null_assert(field_type->as_klass());
 637     } else {
 638       push_translate(field_type);
 639     }
 640   }
 641 }
 642 
 643 // ------------------------------------------------------------------
 644 // ciTypeFlow::StateVector::do_invoke
 645 void ciTypeFlow::StateVector::do_invoke(ciBytecodeStream* str,
 646                                         bool has_receiver) {
 647   bool will_link;
 648   ciSignature* declared_signature = NULL;
 649   ciMethod* callee = str->get_method(will_link, &declared_signature);
 650   assert(declared_signature != NULL, "cannot be null");
 651   if (!will_link) {
 652     // We weren't able to find the method.
 653     if (str->cur_bc() == Bytecodes::_invokedynamic) {
 654       trap(str, NULL,
 655            Deoptimization::make_trap_request
 656            (Deoptimization::Reason_uninitialized,
 657             Deoptimization::Action_reinterpret));
 658     } else {
 659       ciKlass* unloaded_holder = callee->holder();
 660       trap(str, unloaded_holder, str->get_method_holder_index());
 661     }
 662   } else {
 663     // We are using the declared signature here because it might be
 664     // different from the callee signature (Cf. invokedynamic and
 665     // invokehandle).
 666     ciSignatureStream sigstr(declared_signature);
 667     const int arg_size = declared_signature->size();
 668     const int stack_base = stack_size() - arg_size;
 669     int i = 0;
 670     for( ; !sigstr.at_return_type(); sigstr.next()) {
 671       ciType* type = sigstr.type();
 672       ciType* stack_type = type_at(stack(stack_base + i++));
 673       // Do I want to check this type?
 674       // assert(stack_type->is_subtype_of(type), "bad type for field value");
 675       if (type->is_two_word()) {
 676         ciType* stack_type2 = type_at(stack(stack_base + i++));
 677         assert(stack_type2->equals(half_type(type)), "must be 2nd half");
 678       }
 679     }
 680     assert(arg_size == i, "must match");
 681     for (int j = 0; j < arg_size; j++) {
 682       pop();
 683     }
 684     if (has_receiver) {
 685       // Check this?
 686       pop_object();
 687     }
 688     assert(!sigstr.is_done(), "must have return type");
 689     ciType* return_type = sigstr.type();
 690     if (!return_type->is_void()) {
 691       if (!return_type->is_loaded()) {
 692         // As in do_getstatic(), generally speaking, we need the return type to
 693         // be loaded if we are to do anything interesting with its value.
 694         // We used to do this:  trap(str, str->get_method_signature_index());
 695         //
 696         // We do not trap here since execution can get past this invoke if
 697         // the return value is null.  As long as the value is null, the class
 698         // does not need to be loaded!  The compiler must assume that
 699         // the value of the unloaded class reference is null; if the code
 700         // ever sees a non-null value, loading has occurred.
 701         //
 702         // See do_getstatic() for similar explanation, as well as bug 4684993.
 703         do_null_assert(return_type->as_klass());
 704       } else {
 705         push_translate(return_type);
 706       }
 707     }
 708   }
 709 }
 710 
 711 // ------------------------------------------------------------------
 712 // ciTypeFlow::StateVector::do_jsr
 713 void ciTypeFlow::StateVector::do_jsr(ciBytecodeStream* str) {
 714   push(ciReturnAddress::make(str->next_bci()));
 715 }
 716 
 717 // ------------------------------------------------------------------
 718 // ciTypeFlow::StateVector::do_ldc
 719 void ciTypeFlow::StateVector::do_ldc(ciBytecodeStream* str) {
 720   ciConstant con = str->get_constant();
 721   BasicType basic_type = con.basic_type();
 722   if (basic_type == T_ILLEGAL) {
 723     // OutOfMemoryError in the CI while loading constant
 724     push_null();
 725     outer()->record_failure("ldc did not link");
 726     return;
 727   }
 728   if (basic_type == T_OBJECT || basic_type == T_ARRAY) {
 729     ciObject* obj = con.as_object();
 730     if (obj->is_null_object()) {
 731       push_null();
 732     } else {
 733       assert(obj->is_instance() || obj->is_array(), "must be java_mirror of klass");
 734       push_object(obj->klass());
 735     }
 736   } else {
 737     push_translate(ciType::make(basic_type));
 738   }
 739 }
 740 
 741 // ------------------------------------------------------------------
 742 // ciTypeFlow::StateVector::do_multianewarray
 743 void ciTypeFlow::StateVector::do_multianewarray(ciBytecodeStream* str) {
 744   int dimensions = str->get_dimensions();
 745   bool will_link;
 746   ciArrayKlass* array_klass = str->get_klass(will_link)->as_array_klass();
 747   if (!will_link) {
 748     trap(str, array_klass, str->get_klass_index());
 749   } else {
 750     for (int i = 0; i < dimensions; i++) {
 751       pop_int();
 752     }
 753     push_object(array_klass);
 754   }
 755 }
 756 
 757 // ------------------------------------------------------------------
 758 // ciTypeFlow::StateVector::do_new
 759 void ciTypeFlow::StateVector::do_new(ciBytecodeStream* str) {
 760   bool will_link;
 761   ciKlass* klass = str->get_klass(will_link);
 762   if (!will_link || str->is_unresolved_klass()) {
 763     trap(str, klass, str->get_klass_index());
 764   } else {
 765     push_object(klass);
 766   }
 767 }
 768 
 769 // ------------------------------------------------------------------
 770 // ciTypeFlow::StateVector::do_newarray
 771 void ciTypeFlow::StateVector::do_newarray(ciBytecodeStream* str) {
 772   pop_int();
 773   ciKlass* klass = ciTypeArrayKlass::make((BasicType)str->get_index());
 774   push_object(klass);
 775 }
 776 
 777 // ------------------------------------------------------------------
 778 // ciTypeFlow::StateVector::do_putfield
 779 void ciTypeFlow::StateVector::do_putfield(ciBytecodeStream* str) {
 780   do_putstatic(str);
 781   if (_trap_bci != -1)  return;  // unloaded field holder, etc.
 782   // could add assert here for type of object.
 783   pop_object();
 784 }
 785 
 786 // ------------------------------------------------------------------
 787 // ciTypeFlow::StateVector::do_putstatic
 788 void ciTypeFlow::StateVector::do_putstatic(ciBytecodeStream* str) {
 789   bool will_link;
 790   ciField* field = str->get_field(will_link);
 791   if (!will_link) {
 792     trap(str, field->holder(), str->get_field_holder_index());
 793   } else {
 794     ciType* field_type = field->type();
 795     ciType* type = pop_value();
 796     // Do I want to check this type?
 797     //      assert(type->is_subtype_of(field_type), "bad type for field value");
 798     if (field_type->is_two_word()) {
 799       ciType* type2 = pop_value();
 800       assert(type2->is_two_word(), "must be 2nd half");
 801       assert(type == half_type(type2), "must be 2nd half");
 802     }
 803   }
 804 }
 805 
 806 // ------------------------------------------------------------------
 807 // ciTypeFlow::StateVector::do_ret
 808 void ciTypeFlow::StateVector::do_ret(ciBytecodeStream* str) {
 809   Cell index = local(str->get_index());
 810 
 811   ciType* address = type_at(index);
 812   assert(address->is_return_address(), "bad return address");
 813   set_type_at(index, bottom_type());
 814 }
 815 
 816 // ------------------------------------------------------------------
 817 // ciTypeFlow::StateVector::trap
 818 //
 819 // Stop interpretation of this path with a trap.
 820 void ciTypeFlow::StateVector::trap(ciBytecodeStream* str, ciKlass* klass, int index) {
 821   _trap_bci = str->cur_bci();
 822   _trap_index = index;
 823 
 824   // Log information about this trap:
 825   CompileLog* log = outer()->env()->log();
 826   if (log != NULL) {
 827     int mid = log->identify(outer()->method());
 828     int kid = (klass == NULL)? -1: log->identify(klass);
 829     log->begin_elem("uncommon_trap method='%d' bci='%d'", mid, str->cur_bci());
 830     char buf[100];
 831     log->print(" %s", Deoptimization::format_trap_request(buf, sizeof(buf),
 832                                                           index));
 833     if (kid >= 0)
 834       log->print(" klass='%d'", kid);
 835     log->end_elem();
 836   }
 837 }
 838 
 839 // ------------------------------------------------------------------
 840 // ciTypeFlow::StateVector::do_null_assert
 841 // Corresponds to graphKit::do_null_assert.
 842 void ciTypeFlow::StateVector::do_null_assert(ciKlass* unloaded_klass) {
 843   if (unloaded_klass->is_loaded()) {
 844     // We failed to link, but we can still compute with this class,
 845     // since it is loaded somewhere.  The compiler will uncommon_trap
 846     // if the object is not null, but the typeflow pass can not assume
 847     // that the object will be null, otherwise it may incorrectly tell
 848     // the parser that an object is known to be null. 4761344, 4807707
 849     push_object(unloaded_klass);
 850   } else {
 851     // The class is not loaded anywhere.  It is safe to model the
 852     // null in the typestates, because we can compile in a null check
 853     // which will deoptimize us if someone manages to load the
 854     // class later.
 855     push_null();
 856   }
 857 }
 858 
 859 
 860 // ------------------------------------------------------------------
 861 // ciTypeFlow::StateVector::apply_one_bytecode
 862 //
 863 // Apply the effect of one bytecode to this StateVector
 864 bool ciTypeFlow::StateVector::apply_one_bytecode(ciBytecodeStream* str) {
 865   _trap_bci = -1;
 866   _trap_index = 0;
 867 
 868   if (CITraceTypeFlow) {
 869     tty->print_cr(">> Interpreting bytecode %d:%s", str->cur_bci(),
 870                   Bytecodes::name(str->cur_bc()));
 871   }
 872 
 873   switch(str->cur_bc()) {
 874   case Bytecodes::_aaload: do_aaload(str);                       break;
 875 
 876   case Bytecodes::_aastore:
 877     {
 878       pop_object();
 879       pop_int();
 880       pop_objArray();
 881       break;
 882     }
 883   case Bytecodes::_aconst_null:
 884     {
 885       push_null();
 886       break;
 887     }
 888   case Bytecodes::_aload:   load_local_object(str->get_index());    break;
 889   case Bytecodes::_aload_0: load_local_object(0);                   break;
 890   case Bytecodes::_aload_1: load_local_object(1);                   break;
 891   case Bytecodes::_aload_2: load_local_object(2);                   break;
 892   case Bytecodes::_aload_3: load_local_object(3);                   break;
 893 
 894   case Bytecodes::_anewarray:
 895     {
 896       pop_int();
 897       bool will_link;
 898       ciKlass* element_klass = str->get_klass(will_link);
 899       if (!will_link) {
 900         trap(str, element_klass, str->get_klass_index());
 901       } else {
 902         push_object(ciObjArrayKlass::make(element_klass));
 903       }
 904       break;
 905     }
 906   case Bytecodes::_areturn:
 907   case Bytecodes::_ifnonnull:
 908   case Bytecodes::_ifnull:
 909     {
 910       pop_object();
 911       break;
 912     }
 913   case Bytecodes::_monitorenter:
 914     {
 915       pop_object();
 916       set_monitor_count(monitor_count() + 1);
 917       break;
 918     }
 919   case Bytecodes::_monitorexit:
 920     {
 921       pop_object();
 922       assert(monitor_count() > 0, "must be a monitor to exit from");
 923       set_monitor_count(monitor_count() - 1);
 924       break;
 925     }
 926   case Bytecodes::_arraylength:
 927     {
 928       pop_array();
 929       push_int();
 930       break;
 931     }
 932   case Bytecodes::_astore:   store_local_object(str->get_index());  break;
 933   case Bytecodes::_astore_0: store_local_object(0);                 break;
 934   case Bytecodes::_astore_1: store_local_object(1);                 break;
 935   case Bytecodes::_astore_2: store_local_object(2);                 break;
 936   case Bytecodes::_astore_3: store_local_object(3);                 break;
 937 
 938   case Bytecodes::_athrow:
 939     {
 940       NEEDS_CLEANUP;
 941       pop_object();
 942       break;
 943     }
 944   case Bytecodes::_baload:
 945   case Bytecodes::_caload:
 946   case Bytecodes::_iaload:
 947   case Bytecodes::_saload:
 948     {
 949       pop_int();
 950       ciTypeArrayKlass* array_klass = pop_typeArray();
 951       // Put assert here for right type?
 952       push_int();
 953       break;
 954     }
 955   case Bytecodes::_bastore:
 956   case Bytecodes::_castore:
 957   case Bytecodes::_iastore:
 958   case Bytecodes::_sastore:
 959     {
 960       pop_int();
 961       pop_int();
 962       pop_typeArray();
 963       // assert here?
 964       break;
 965     }
 966   case Bytecodes::_bipush:
 967   case Bytecodes::_iconst_m1:
 968   case Bytecodes::_iconst_0:
 969   case Bytecodes::_iconst_1:
 970   case Bytecodes::_iconst_2:
 971   case Bytecodes::_iconst_3:
 972   case Bytecodes::_iconst_4:
 973   case Bytecodes::_iconst_5:
 974   case Bytecodes::_sipush:
 975     {
 976       push_int();
 977       break;
 978     }
 979   case Bytecodes::_checkcast: do_checkcast(str);                  break;
 980 
 981   case Bytecodes::_d2f:
 982     {
 983       pop_double();
 984       push_float();
 985       break;
 986     }
 987   case Bytecodes::_d2i:
 988     {
 989       pop_double();
 990       push_int();
 991       break;
 992     }
 993   case Bytecodes::_d2l:
 994     {
 995       pop_double();
 996       push_long();
 997       break;
 998     }
 999   case Bytecodes::_dadd:
1000   case Bytecodes::_ddiv:
1001   case Bytecodes::_dmul:
1002   case Bytecodes::_drem:
1003   case Bytecodes::_dsub:
1004     {
1005       pop_double();
1006       pop_double();
1007       push_double();
1008       break;
1009     }
1010   case Bytecodes::_daload:
1011     {
1012       pop_int();
1013       ciTypeArrayKlass* array_klass = pop_typeArray();
1014       // Put assert here for right type?
1015       push_double();
1016       break;
1017     }
1018   case Bytecodes::_dastore:
1019     {
1020       pop_double();
1021       pop_int();
1022       pop_typeArray();
1023       // assert here?
1024       break;
1025     }
1026   case Bytecodes::_dcmpg:
1027   case Bytecodes::_dcmpl:
1028     {
1029       pop_double();
1030       pop_double();
1031       push_int();
1032       break;
1033     }
1034   case Bytecodes::_dconst_0:
1035   case Bytecodes::_dconst_1:
1036     {
1037       push_double();
1038       break;
1039     }
1040   case Bytecodes::_dload:   load_local_double(str->get_index());    break;
1041   case Bytecodes::_dload_0: load_local_double(0);                   break;
1042   case Bytecodes::_dload_1: load_local_double(1);                   break;
1043   case Bytecodes::_dload_2: load_local_double(2);                   break;
1044   case Bytecodes::_dload_3: load_local_double(3);                   break;
1045 
1046   case Bytecodes::_dneg:
1047     {
1048       pop_double();
1049       push_double();
1050       break;
1051     }
1052   case Bytecodes::_dreturn:
1053     {
1054       pop_double();
1055       break;
1056     }
1057   case Bytecodes::_dstore:   store_local_double(str->get_index());  break;
1058   case Bytecodes::_dstore_0: store_local_double(0);                 break;
1059   case Bytecodes::_dstore_1: store_local_double(1);                 break;
1060   case Bytecodes::_dstore_2: store_local_double(2);                 break;
1061   case Bytecodes::_dstore_3: store_local_double(3);                 break;
1062 
1063   case Bytecodes::_dup:
1064     {
1065       push(type_at_tos());
1066       break;
1067     }
1068   case Bytecodes::_dup_x1:
1069     {
1070       ciType* value1 = pop_value();
1071       ciType* value2 = pop_value();
1072       push(value1);
1073       push(value2);
1074       push(value1);
1075       break;
1076     }
1077   case Bytecodes::_dup_x2:
1078     {
1079       ciType* value1 = pop_value();
1080       ciType* value2 = pop_value();
1081       ciType* value3 = pop_value();
1082       push(value1);
1083       push(value3);
1084       push(value2);
1085       push(value1);
1086       break;
1087     }
1088   case Bytecodes::_dup2:
1089     {
1090       ciType* value1 = pop_value();
1091       ciType* value2 = pop_value();
1092       push(value2);
1093       push(value1);
1094       push(value2);
1095       push(value1);
1096       break;
1097     }
1098   case Bytecodes::_dup2_x1:
1099     {
1100       ciType* value1 = pop_value();
1101       ciType* value2 = pop_value();
1102       ciType* value3 = pop_value();
1103       push(value2);
1104       push(value1);
1105       push(value3);
1106       push(value2);
1107       push(value1);
1108       break;
1109     }
1110   case Bytecodes::_dup2_x2:
1111     {
1112       ciType* value1 = pop_value();
1113       ciType* value2 = pop_value();
1114       ciType* value3 = pop_value();
1115       ciType* value4 = pop_value();
1116       push(value2);
1117       push(value1);
1118       push(value4);
1119       push(value3);
1120       push(value2);
1121       push(value1);
1122       break;
1123     }
1124   case Bytecodes::_f2d:
1125     {
1126       pop_float();
1127       push_double();
1128       break;
1129     }
1130   case Bytecodes::_f2i:
1131     {
1132       pop_float();
1133       push_int();
1134       break;
1135     }
1136   case Bytecodes::_f2l:
1137     {
1138       pop_float();
1139       push_long();
1140       break;
1141     }
1142   case Bytecodes::_fadd:
1143   case Bytecodes::_fdiv:
1144   case Bytecodes::_fmul:
1145   case Bytecodes::_frem:
1146   case Bytecodes::_fsub:
1147     {
1148       pop_float();
1149       pop_float();
1150       push_float();
1151       break;
1152     }
1153   case Bytecodes::_faload:
1154     {
1155       pop_int();
1156       ciTypeArrayKlass* array_klass = pop_typeArray();
1157       // Put assert here.
1158       push_float();
1159       break;
1160     }
1161   case Bytecodes::_fastore:
1162     {
1163       pop_float();
1164       pop_int();
1165       ciTypeArrayKlass* array_klass = pop_typeArray();
1166       // Put assert here.
1167       break;
1168     }
1169   case Bytecodes::_fcmpg:
1170   case Bytecodes::_fcmpl:
1171     {
1172       pop_float();
1173       pop_float();
1174       push_int();
1175       break;
1176     }
1177   case Bytecodes::_fconst_0:
1178   case Bytecodes::_fconst_1:
1179   case Bytecodes::_fconst_2:
1180     {
1181       push_float();
1182       break;
1183     }
1184   case Bytecodes::_fload:   load_local_float(str->get_index());     break;
1185   case Bytecodes::_fload_0: load_local_float(0);                    break;
1186   case Bytecodes::_fload_1: load_local_float(1);                    break;
1187   case Bytecodes::_fload_2: load_local_float(2);                    break;
1188   case Bytecodes::_fload_3: load_local_float(3);                    break;
1189 
1190   case Bytecodes::_fneg:
1191     {
1192       pop_float();
1193       push_float();
1194       break;
1195     }
1196   case Bytecodes::_freturn:
1197     {
1198       pop_float();
1199       break;
1200     }
1201   case Bytecodes::_fstore:    store_local_float(str->get_index());   break;
1202   case Bytecodes::_fstore_0:  store_local_float(0);                  break;
1203   case Bytecodes::_fstore_1:  store_local_float(1);                  break;
1204   case Bytecodes::_fstore_2:  store_local_float(2);                  break;
1205   case Bytecodes::_fstore_3:  store_local_float(3);                  break;
1206 
1207   case Bytecodes::_getfield:  do_getfield(str);                      break;
1208   case Bytecodes::_getstatic: do_getstatic(str);                     break;
1209 
1210   case Bytecodes::_goto:
1211   case Bytecodes::_goto_w:
1212   case Bytecodes::_nop:
1213   case Bytecodes::_return:
1214     {
1215       // do nothing.
1216       break;
1217     }
1218   case Bytecodes::_i2b:
1219   case Bytecodes::_i2c:
1220   case Bytecodes::_i2s:
1221   case Bytecodes::_ineg:
1222     {
1223       pop_int();
1224       push_int();
1225       break;
1226     }
1227   case Bytecodes::_i2d:
1228     {
1229       pop_int();
1230       push_double();
1231       break;
1232     }
1233   case Bytecodes::_i2f:
1234     {
1235       pop_int();
1236       push_float();
1237       break;
1238     }
1239   case Bytecodes::_i2l:
1240     {
1241       pop_int();
1242       push_long();
1243       break;
1244     }
1245   case Bytecodes::_iadd:
1246   case Bytecodes::_iand:
1247   case Bytecodes::_idiv:
1248   case Bytecodes::_imul:
1249   case Bytecodes::_ior:
1250   case Bytecodes::_irem:
1251   case Bytecodes::_ishl:
1252   case Bytecodes::_ishr:
1253   case Bytecodes::_isub:
1254   case Bytecodes::_iushr:
1255   case Bytecodes::_ixor:
1256     {
1257       pop_int();
1258       pop_int();
1259       push_int();
1260       break;
1261     }
1262   case Bytecodes::_if_acmpeq:
1263   case Bytecodes::_if_acmpne:
1264     {
1265       pop_object();
1266       pop_object();
1267       break;
1268     }
1269   case Bytecodes::_if_icmpeq:
1270   case Bytecodes::_if_icmpge:
1271   case Bytecodes::_if_icmpgt:
1272   case Bytecodes::_if_icmple:
1273   case Bytecodes::_if_icmplt:
1274   case Bytecodes::_if_icmpne:
1275     {
1276       pop_int();
1277       pop_int();
1278       break;
1279     }
1280   case Bytecodes::_ifeq:
1281   case Bytecodes::_ifle:
1282   case Bytecodes::_iflt:
1283   case Bytecodes::_ifge:
1284   case Bytecodes::_ifgt:
1285   case Bytecodes::_ifne:
1286   case Bytecodes::_ireturn:
1287   case Bytecodes::_lookupswitch:
1288   case Bytecodes::_tableswitch:
1289     {
1290       pop_int();
1291       break;
1292     }
1293   case Bytecodes::_iinc:
1294     {
1295       int lnum = str->get_index();
1296       check_int(local(lnum));
1297       store_to_local(lnum);
1298       break;
1299     }
1300   case Bytecodes::_iload:   load_local_int(str->get_index()); break;
1301   case Bytecodes::_iload_0: load_local_int(0);                      break;
1302   case Bytecodes::_iload_1: load_local_int(1);                      break;
1303   case Bytecodes::_iload_2: load_local_int(2);                      break;
1304   case Bytecodes::_iload_3: load_local_int(3);                      break;
1305 
1306   case Bytecodes::_instanceof:
1307     {
1308       // Check for uncommon trap:
1309       do_checkcast(str);
1310       pop_object();
1311       push_int();
1312       break;
1313     }
1314   case Bytecodes::_invokeinterface: do_invoke(str, true);           break;
1315   case Bytecodes::_invokespecial:   do_invoke(str, true);           break;
1316   case Bytecodes::_invokestatic:    do_invoke(str, false);          break;
1317   case Bytecodes::_invokevirtual:   do_invoke(str, true);           break;
1318   case Bytecodes::_invokedynamic:   do_invoke(str, false);          break;
1319 
1320   case Bytecodes::_istore:   store_local_int(str->get_index());     break;
1321   case Bytecodes::_istore_0: store_local_int(0);                    break;
1322   case Bytecodes::_istore_1: store_local_int(1);                    break;
1323   case Bytecodes::_istore_2: store_local_int(2);                    break;
1324   case Bytecodes::_istore_3: store_local_int(3);                    break;
1325 
1326   case Bytecodes::_jsr:
1327   case Bytecodes::_jsr_w: do_jsr(str);                              break;
1328 
1329   case Bytecodes::_l2d:
1330     {
1331       pop_long();
1332       push_double();
1333       break;
1334     }
1335   case Bytecodes::_l2f:
1336     {
1337       pop_long();
1338       push_float();
1339       break;
1340     }
1341   case Bytecodes::_l2i:
1342     {
1343       pop_long();
1344       push_int();
1345       break;
1346     }
1347   case Bytecodes::_ladd:
1348   case Bytecodes::_land:
1349   case Bytecodes::_ldiv:
1350   case Bytecodes::_lmul:
1351   case Bytecodes::_lor:
1352   case Bytecodes::_lrem:
1353   case Bytecodes::_lsub:
1354   case Bytecodes::_lxor:
1355     {
1356       pop_long();
1357       pop_long();
1358       push_long();
1359       break;
1360     }
1361   case Bytecodes::_laload:
1362     {
1363       pop_int();
1364       ciTypeArrayKlass* array_klass = pop_typeArray();
1365       // Put assert here for right type?
1366       push_long();
1367       break;
1368     }
1369   case Bytecodes::_lastore:
1370     {
1371       pop_long();
1372       pop_int();
1373       pop_typeArray();
1374       // assert here?
1375       break;
1376     }
1377   case Bytecodes::_lcmp:
1378     {
1379       pop_long();
1380       pop_long();
1381       push_int();
1382       break;
1383     }
1384   case Bytecodes::_lconst_0:
1385   case Bytecodes::_lconst_1:
1386     {
1387       push_long();
1388       break;
1389     }
1390   case Bytecodes::_ldc:
1391   case Bytecodes::_ldc_w:
1392   case Bytecodes::_ldc2_w:
1393     {
1394       do_ldc(str);
1395       break;
1396     }
1397 
1398   case Bytecodes::_lload:   load_local_long(str->get_index());      break;
1399   case Bytecodes::_lload_0: load_local_long(0);                     break;
1400   case Bytecodes::_lload_1: load_local_long(1);                     break;
1401   case Bytecodes::_lload_2: load_local_long(2);                     break;
1402   case Bytecodes::_lload_3: load_local_long(3);                     break;
1403 
1404   case Bytecodes::_lneg:
1405     {
1406       pop_long();
1407       push_long();
1408       break;
1409     }
1410   case Bytecodes::_lreturn:
1411     {
1412       pop_long();
1413       break;
1414     }
1415   case Bytecodes::_lshl:
1416   case Bytecodes::_lshr:
1417   case Bytecodes::_lushr:
1418     {
1419       pop_int();
1420       pop_long();
1421       push_long();
1422       break;
1423     }
1424   case Bytecodes::_lstore:   store_local_long(str->get_index());    break;
1425   case Bytecodes::_lstore_0: store_local_long(0);                   break;
1426   case Bytecodes::_lstore_1: store_local_long(1);                   break;
1427   case Bytecodes::_lstore_2: store_local_long(2);                   break;
1428   case Bytecodes::_lstore_3: store_local_long(3);                   break;
1429 
1430   case Bytecodes::_multianewarray: do_multianewarray(str);          break;
1431 
1432   case Bytecodes::_new:      do_new(str);                           break;
1433 
1434   case Bytecodes::_newarray: do_newarray(str);                      break;
1435 
1436   case Bytecodes::_pop:
1437     {
1438       pop();
1439       break;
1440     }
1441   case Bytecodes::_pop2:
1442     {
1443       pop();
1444       pop();
1445       break;
1446     }
1447 
1448   case Bytecodes::_putfield:       do_putfield(str);                 break;
1449   case Bytecodes::_putstatic:      do_putstatic(str);                break;
1450 
1451   case Bytecodes::_ret: do_ret(str);                                 break;
1452 
1453   case Bytecodes::_swap:
1454     {
1455       ciType* value1 = pop_value();
1456       ciType* value2 = pop_value();
1457       push(value1);
1458       push(value2);
1459       break;
1460     }
1461   case Bytecodes::_wide:
1462   default:
1463     {
1464       // The iterator should skip this.
1465       ShouldNotReachHere();
1466       break;
1467     }
1468   }
1469 
1470   if (CITraceTypeFlow) {
1471     print_on(tty);
1472   }
1473 
1474   return (_trap_bci != -1);
1475 }
1476 
1477 #ifndef PRODUCT
1478 // ------------------------------------------------------------------
1479 // ciTypeFlow::StateVector::print_cell_on
1480 void ciTypeFlow::StateVector::print_cell_on(outputStream* st, Cell c) const {
1481   ciType* type = type_at(c);
1482   if (type == top_type()) {
1483     st->print("top");
1484   } else if (type == bottom_type()) {
1485     st->print("bottom");
1486   } else if (type == null_type()) {
1487     st->print("null");
1488   } else if (type == long2_type()) {
1489     st->print("long2");
1490   } else if (type == double2_type()) {
1491     st->print("double2");
1492   } else if (is_int(type)) {
1493     st->print("int");
1494   } else if (is_long(type)) {
1495     st->print("long");
1496   } else if (is_float(type)) {
1497     st->print("float");
1498   } else if (is_double(type)) {
1499     st->print("double");
1500   } else if (type->is_return_address()) {
1501     st->print("address(%d)", type->as_return_address()->bci());
1502   } else {
1503     if (type->is_klass()) {
1504       type->as_klass()->name()->print_symbol_on(st);
1505     } else {
1506       st->print("UNEXPECTED TYPE");
1507       type->print();
1508     }
1509   }
1510 }
1511 
1512 // ------------------------------------------------------------------
1513 // ciTypeFlow::StateVector::print_on
1514 void ciTypeFlow::StateVector::print_on(outputStream* st) const {
1515   int num_locals   = _outer->max_locals();
1516   int num_stack    = stack_size();
1517   int num_monitors = monitor_count();
1518   st->print_cr("  State : locals %d, stack %d, monitors %d", num_locals, num_stack, num_monitors);
1519   if (num_stack >= 0) {
1520     int i;
1521     for (i = 0; i < num_locals; i++) {
1522       st->print("    local %2d : ", i);
1523       print_cell_on(st, local(i));
1524       st->cr();
1525     }
1526     for (i = 0; i < num_stack; i++) {
1527       st->print("    stack %2d : ", i);
1528       print_cell_on(st, stack(i));
1529       st->cr();
1530     }
1531   }
1532 }
1533 #endif
1534 
1535 
1536 // ------------------------------------------------------------------
1537 // ciTypeFlow::SuccIter::next
1538 //
1539 void ciTypeFlow::SuccIter::next() {
1540   int succ_ct = _pred->successors()->length();
1541   int next = _index + 1;
1542   if (next < succ_ct) {
1543     _index = next;
1544     _succ = _pred->successors()->at(next);
1545     return;
1546   }
1547   for (int i = next - succ_ct; i < _pred->exceptions()->length(); i++) {
1548     // Do not compile any code for unloaded exception types.
1549     // Following compiler passes are responsible for doing this also.
1550     ciInstanceKlass* exception_klass = _pred->exc_klasses()->at(i);
1551     if (exception_klass->is_loaded()) {
1552       _index = next;
1553       _succ = _pred->exceptions()->at(i);
1554       return;
1555     }
1556     next++;
1557   }
1558   _index = -1;
1559   _succ = NULL;
1560 }
1561 
1562 // ------------------------------------------------------------------
1563 // ciTypeFlow::SuccIter::set_succ
1564 //
1565 void ciTypeFlow::SuccIter::set_succ(Block* succ) {
1566   int succ_ct = _pred->successors()->length();
1567   if (_index < succ_ct) {
1568     _pred->successors()->at_put(_index, succ);
1569   } else {
1570     int idx = _index - succ_ct;
1571     _pred->exceptions()->at_put(idx, succ);
1572   }
1573 }
1574 
1575 // ciTypeFlow::Block
1576 //
1577 // A basic block.
1578 
1579 // ------------------------------------------------------------------
1580 // ciTypeFlow::Block::Block
1581 ciTypeFlow::Block::Block(ciTypeFlow* outer,
1582                          ciBlock *ciblk,
1583                          ciTypeFlow::JsrSet* jsrs) {
1584   _ciblock = ciblk;
1585   _exceptions = NULL;
1586   _exc_klasses = NULL;
1587   _successors = NULL;
1588   _state = new (outer->arena()) StateVector(outer);
1589   JsrSet* new_jsrs =
1590     new (outer->arena()) JsrSet(outer->arena(), jsrs->size());
1591   jsrs->copy_into(new_jsrs);
1592   _jsrs = new_jsrs;
1593   _next = NULL;
1594   _on_work_list = false;
1595   _backedge_copy = false;
1596   _has_monitorenter = false;
1597   _trap_bci = -1;
1598   _trap_index = 0;
1599   df_init();
1600 
1601   if (CITraceTypeFlow) {
1602     tty->print_cr(">> Created new block");
1603     print_on(tty);
1604   }
1605 
1606   assert(this->outer() == outer, "outer link set up");
1607   assert(!outer->have_block_count(), "must not have mapped blocks yet");
1608 }
1609 
1610 // ------------------------------------------------------------------
1611 // ciTypeFlow::Block::df_init
1612 void ciTypeFlow::Block::df_init() {
1613   _pre_order = -1; assert(!has_pre_order(), "");
1614   _post_order = -1; assert(!has_post_order(), "");
1615   _loop = NULL;
1616   _irreducible_entry = false;
1617   _rpo_next = NULL;
1618 }
1619 
1620 // ------------------------------------------------------------------
1621 // ciTypeFlow::Block::successors
1622 //
1623 // Get the successors for this Block.
1624 GrowableArray<ciTypeFlow::Block*>*
1625 ciTypeFlow::Block::successors(ciBytecodeStream* str,
1626                               ciTypeFlow::StateVector* state,
1627                               ciTypeFlow::JsrSet* jsrs) {
1628   if (_successors == NULL) {
1629     if (CITraceTypeFlow) {
1630       tty->print(">> Computing successors for block ");
1631       print_value_on(tty);
1632       tty->cr();
1633     }
1634 
1635     ciTypeFlow* analyzer = outer();
1636     Arena* arena = analyzer->arena();
1637     Block* block = NULL;
1638     bool has_successor = !has_trap() &&
1639                          (control() != ciBlock::fall_through_bci || limit() < analyzer->code_size());
1640     if (!has_successor) {
1641       _successors =
1642         new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1643       // No successors
1644     } else if (control() == ciBlock::fall_through_bci) {
1645       assert(str->cur_bci() == limit(), "bad block end");
1646       // This block simply falls through to the next.
1647       _successors =
1648         new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1649 
1650       Block* block = analyzer->block_at(limit(), _jsrs);
1651       assert(_successors->length() == FALL_THROUGH, "");
1652       _successors->append(block);
1653     } else {
1654       int current_bci = str->cur_bci();
1655       int next_bci = str->next_bci();
1656       int branch_bci = -1;
1657       Block* target = NULL;
1658       assert(str->next_bci() == limit(), "bad block end");
1659       // This block is not a simple fall-though.  Interpret
1660       // the current bytecode to find our successors.
1661       switch (str->cur_bc()) {
1662       case Bytecodes::_ifeq:         case Bytecodes::_ifne:
1663       case Bytecodes::_iflt:         case Bytecodes::_ifge:
1664       case Bytecodes::_ifgt:         case Bytecodes::_ifle:
1665       case Bytecodes::_if_icmpeq:    case Bytecodes::_if_icmpne:
1666       case Bytecodes::_if_icmplt:    case Bytecodes::_if_icmpge:
1667       case Bytecodes::_if_icmpgt:    case Bytecodes::_if_icmple:
1668       case Bytecodes::_if_acmpeq:    case Bytecodes::_if_acmpne:
1669       case Bytecodes::_ifnull:       case Bytecodes::_ifnonnull:
1670         // Our successors are the branch target and the next bci.
1671         branch_bci = str->get_dest();
1672         _successors =
1673           new (arena) GrowableArray<Block*>(arena, 2, 0, NULL);
1674         assert(_successors->length() == IF_NOT_TAKEN, "");
1675         _successors->append(analyzer->block_at(next_bci, jsrs));
1676         assert(_successors->length() == IF_TAKEN, "");
1677         _successors->append(analyzer->block_at(branch_bci, jsrs));
1678         break;
1679 
1680       case Bytecodes::_goto:
1681         branch_bci = str->get_dest();
1682         _successors =
1683           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1684         assert(_successors->length() == GOTO_TARGET, "");
1685         _successors->append(analyzer->block_at(branch_bci, jsrs));
1686         break;
1687 
1688       case Bytecodes::_jsr:
1689         branch_bci = str->get_dest();
1690         _successors =
1691           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1692         assert(_successors->length() == GOTO_TARGET, "");
1693         _successors->append(analyzer->block_at(branch_bci, jsrs));
1694         break;
1695 
1696       case Bytecodes::_goto_w:
1697       case Bytecodes::_jsr_w:
1698         _successors =
1699           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1700         assert(_successors->length() == GOTO_TARGET, "");
1701         _successors->append(analyzer->block_at(str->get_far_dest(), jsrs));
1702         break;
1703 
1704       case Bytecodes::_tableswitch:  {
1705         Bytecode_tableswitch tableswitch(str);
1706 
1707         int len = tableswitch.length();
1708         _successors =
1709           new (arena) GrowableArray<Block*>(arena, len+1, 0, NULL);
1710         int bci = current_bci + tableswitch.default_offset();
1711         Block* block = analyzer->block_at(bci, jsrs);
1712         assert(_successors->length() == SWITCH_DEFAULT, "");
1713         _successors->append(block);
1714         while (--len >= 0) {
1715           int bci = current_bci + tableswitch.dest_offset_at(len);
1716           block = analyzer->block_at(bci, jsrs);
1717           assert(_successors->length() >= SWITCH_CASES, "");
1718           _successors->append_if_missing(block);
1719         }
1720         break;
1721       }
1722 
1723       case Bytecodes::_lookupswitch: {
1724         Bytecode_lookupswitch lookupswitch(str);
1725 
1726         int npairs = lookupswitch.number_of_pairs();
1727         _successors =
1728           new (arena) GrowableArray<Block*>(arena, npairs+1, 0, NULL);
1729         int bci = current_bci + lookupswitch.default_offset();
1730         Block* block = analyzer->block_at(bci, jsrs);
1731         assert(_successors->length() == SWITCH_DEFAULT, "");
1732         _successors->append(block);
1733         while(--npairs >= 0) {
1734           LookupswitchPair pair = lookupswitch.pair_at(npairs);
1735           int bci = current_bci + pair.offset();
1736           Block* block = analyzer->block_at(bci, jsrs);
1737           assert(_successors->length() >= SWITCH_CASES, "");
1738           _successors->append_if_missing(block);
1739         }
1740         break;
1741       }
1742 
1743       case Bytecodes::_athrow:     case Bytecodes::_ireturn:
1744       case Bytecodes::_lreturn:    case Bytecodes::_freturn:
1745       case Bytecodes::_dreturn:    case Bytecodes::_areturn:
1746       case Bytecodes::_return:
1747         _successors =
1748           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1749         // No successors
1750         break;
1751 
1752       case Bytecodes::_ret: {
1753         _successors =
1754           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1755 
1756         Cell local = state->local(str->get_index());
1757         ciType* return_address = state->type_at(local);
1758         assert(return_address->is_return_address(), "verify: wrong type");
1759         int bci = return_address->as_return_address()->bci();
1760         assert(_successors->length() == GOTO_TARGET, "");
1761         _successors->append(analyzer->block_at(bci, jsrs));
1762         break;
1763       }
1764 
1765       case Bytecodes::_wide:
1766       default:
1767         ShouldNotReachHere();
1768         break;
1769       }
1770     }
1771   }
1772   return _successors;
1773 }
1774 
1775 // ------------------------------------------------------------------
1776 // ciTypeFlow::Block:compute_exceptions
1777 //
1778 // Compute the exceptional successors and types for this Block.
1779 void ciTypeFlow::Block::compute_exceptions() {
1780   assert(_exceptions == NULL && _exc_klasses == NULL, "repeat");
1781 
1782   if (CITraceTypeFlow) {
1783     tty->print(">> Computing exceptions for block ");
1784     print_value_on(tty);
1785     tty->cr();
1786   }
1787 
1788   ciTypeFlow* analyzer = outer();
1789   Arena* arena = analyzer->arena();
1790 
1791   // Any bci in the block will do.
1792   ciExceptionHandlerStream str(analyzer->method(), start());
1793 
1794   // Allocate our growable arrays.
1795   int exc_count = str.count();
1796   _exceptions = new (arena) GrowableArray<Block*>(arena, exc_count, 0, NULL);
1797   _exc_klasses = new (arena) GrowableArray<ciInstanceKlass*>(arena, exc_count,
1798                                                              0, NULL);
1799 
1800   for ( ; !str.is_done(); str.next()) {
1801     ciExceptionHandler* handler = str.handler();
1802     int bci = handler->handler_bci();
1803     ciInstanceKlass* klass = NULL;
1804     if (bci == -1) {
1805       // There is no catch all.  It is possible to exit the method.
1806       break;
1807     }
1808     if (handler->is_catch_all()) {
1809       klass = analyzer->env()->Throwable_klass();
1810     } else {
1811       klass = handler->catch_klass();
1812     }
1813     _exceptions->append(analyzer->block_at(bci, _jsrs));
1814     _exc_klasses->append(klass);
1815   }
1816 }
1817 
1818 // ------------------------------------------------------------------
1819 // ciTypeFlow::Block::set_backedge_copy
1820 // Use this only to make a pre-existing public block into a backedge copy.
1821 void ciTypeFlow::Block::set_backedge_copy(bool z) {
1822   assert(z || (z == is_backedge_copy()), "cannot make a backedge copy public");
1823   _backedge_copy = z;
1824 }
1825 
1826 // ------------------------------------------------------------------
1827 // ciTypeFlow::Block::is_clonable_exit
1828 //
1829 // At most 2 normal successors, one of which continues looping,
1830 // and all exceptional successors must exit.
1831 bool ciTypeFlow::Block::is_clonable_exit(ciTypeFlow::Loop* lp) {
1832   int normal_cnt  = 0;
1833   int in_loop_cnt = 0;
1834   for (SuccIter iter(this); !iter.done(); iter.next()) {
1835     Block* succ = iter.succ();
1836     if (iter.is_normal_ctrl()) {
1837       if (++normal_cnt > 2) return false;
1838       if (lp->contains(succ->loop())) {
1839         if (++in_loop_cnt > 1) return false;
1840       }
1841     } else {
1842       if (lp->contains(succ->loop())) return false;
1843     }
1844   }
1845   return in_loop_cnt == 1;
1846 }
1847 
1848 // ------------------------------------------------------------------
1849 // ciTypeFlow::Block::looping_succ
1850 //
1851 ciTypeFlow::Block* ciTypeFlow::Block::looping_succ(ciTypeFlow::Loop* lp) {
1852   assert(successors()->length() <= 2, "at most 2 normal successors");
1853   for (SuccIter iter(this); !iter.done(); iter.next()) {
1854     Block* succ = iter.succ();
1855     if (lp->contains(succ->loop())) {
1856       return succ;
1857     }
1858   }
1859   return NULL;
1860 }
1861 
1862 #ifndef PRODUCT
1863 // ------------------------------------------------------------------
1864 // ciTypeFlow::Block::print_value_on
1865 void ciTypeFlow::Block::print_value_on(outputStream* st) const {
1866   if (has_pre_order()) st->print("#%-2d ", pre_order());
1867   if (has_rpo())       st->print("rpo#%-2d ", rpo());
1868   st->print("[%d - %d)", start(), limit());
1869   if (is_loop_head()) st->print(" lphd");
1870   if (is_irreducible_entry()) st->print(" irred");
1871   if (_jsrs->size() > 0) { st->print("/");  _jsrs->print_on(st); }
1872   if (is_backedge_copy())  st->print("/backedge_copy");
1873 }
1874 
1875 // ------------------------------------------------------------------
1876 // ciTypeFlow::Block::print_on
1877 void ciTypeFlow::Block::print_on(outputStream* st) const {
1878   if ((Verbose || WizardMode) && (limit() >= 0)) {
1879     // Don't print 'dummy' blocks (i.e. blocks with limit() '-1')
1880     outer()->method()->print_codes_on(start(), limit(), st);
1881   }
1882   st->print_cr("  ====================================================  ");
1883   st->print ("  ");
1884   print_value_on(st);
1885   st->print(" Stored locals: "); def_locals()->print_on(st, outer()->method()->max_locals()); tty->cr();
1886   if (loop() && loop()->parent() != NULL) {
1887     st->print(" loops:");
1888     Loop* lp = loop();
1889     do {
1890       st->print(" %d<-%d", lp->head()->pre_order(),lp->tail()->pre_order());
1891       if (lp->is_irreducible()) st->print("(ir)");
1892       lp = lp->parent();
1893     } while (lp->parent() != NULL);
1894   }
1895   st->cr();
1896   _state->print_on(st);
1897   if (_successors == NULL) {
1898     st->print_cr("  No successor information");
1899   } else {
1900     int num_successors = _successors->length();
1901     st->print_cr("  Successors : %d", num_successors);
1902     for (int i = 0; i < num_successors; i++) {
1903       Block* successor = _successors->at(i);
1904       st->print("    ");
1905       successor->print_value_on(st);
1906       st->cr();
1907     }
1908   }
1909   if (_exceptions == NULL) {
1910     st->print_cr("  No exception information");
1911   } else {
1912     int num_exceptions = _exceptions->length();
1913     st->print_cr("  Exceptions : %d", num_exceptions);
1914     for (int i = 0; i < num_exceptions; i++) {
1915       Block* exc_succ = _exceptions->at(i);
1916       ciInstanceKlass* exc_klass = _exc_klasses->at(i);
1917       st->print("    ");
1918       exc_succ->print_value_on(st);
1919       st->print(" -- ");
1920       exc_klass->name()->print_symbol_on(st);
1921       st->cr();
1922     }
1923   }
1924   if (has_trap()) {
1925     st->print_cr("  Traps on %d with trap index %d", trap_bci(), trap_index());
1926   }
1927   st->print_cr("  ====================================================  ");
1928 }
1929 #endif
1930 
1931 #ifndef PRODUCT
1932 // ------------------------------------------------------------------
1933 // ciTypeFlow::LocalSet::print_on
1934 void ciTypeFlow::LocalSet::print_on(outputStream* st, int limit) const {
1935   st->print("{");
1936   for (int i = 0; i < max; i++) {
1937     if (test(i)) st->print(" %d", i);
1938   }
1939   if (limit > max) {
1940     st->print(" %d..%d ", max, limit);
1941   }
1942   st->print(" }");
1943 }
1944 #endif
1945 
1946 // ciTypeFlow
1947 //
1948 // This is a pass over the bytecodes which computes the following:
1949 //   basic block structure
1950 //   interpreter type-states (a la the verifier)
1951 
1952 // ------------------------------------------------------------------
1953 // ciTypeFlow::ciTypeFlow
1954 ciTypeFlow::ciTypeFlow(ciEnv* env, ciMethod* method, int osr_bci) {
1955   _env = env;
1956   _method = method;
1957   _methodBlocks = method->get_method_blocks();
1958   _max_locals = method->max_locals();
1959   _max_stack = method->max_stack();
1960   _code_size = method->code_size();
1961   _has_irreducible_entry = false;
1962   _osr_bci = osr_bci;
1963   _failure_reason = NULL;
1964   assert(0 <= start_bci() && start_bci() < code_size() , err_msg("correct osr_bci argument: 0 <= %d < %d", start_bci(), code_size()));
1965   _work_list = NULL;
1966 
1967   _ciblock_count = _methodBlocks->num_blocks();
1968   _idx_to_blocklist = NEW_ARENA_ARRAY(arena(), GrowableArray<Block*>*, _ciblock_count);
1969   for (int i = 0; i < _ciblock_count; i++) {
1970     _idx_to_blocklist[i] = NULL;
1971   }
1972   _block_map = NULL;  // until all blocks are seen
1973   _jsr_count = 0;
1974   _jsr_records = NULL;
1975 }
1976 
1977 // ------------------------------------------------------------------
1978 // ciTypeFlow::work_list_next
1979 //
1980 // Get the next basic block from our work list.
1981 ciTypeFlow::Block* ciTypeFlow::work_list_next() {
1982   assert(!work_list_empty(), "work list must not be empty");
1983   Block* next_block = _work_list;
1984   _work_list = next_block->next();
1985   next_block->set_next(NULL);
1986   next_block->set_on_work_list(false);
1987   return next_block;
1988 }
1989 
1990 // ------------------------------------------------------------------
1991 // ciTypeFlow::add_to_work_list
1992 //
1993 // Add a basic block to our work list.
1994 // List is sorted by decreasing postorder sort (same as increasing RPO)
1995 void ciTypeFlow::add_to_work_list(ciTypeFlow::Block* block) {
1996   assert(!block->is_on_work_list(), "must not already be on work list");
1997 
1998   if (CITraceTypeFlow) {
1999     tty->print(">> Adding block ");
2000     block->print_value_on(tty);
2001     tty->print_cr(" to the work list : ");
2002   }
2003 
2004   block->set_on_work_list(true);
2005 
2006   // decreasing post order sort
2007 
2008   Block* prev = NULL;
2009   Block* current = _work_list;
2010   int po = block->post_order();
2011   while (current != NULL) {
2012     if (!current->has_post_order() || po > current->post_order())
2013       break;
2014     prev = current;
2015     current = current->next();
2016   }
2017   if (prev == NULL) {
2018     block->set_next(_work_list);
2019     _work_list = block;
2020   } else {
2021     block->set_next(current);
2022     prev->set_next(block);
2023   }
2024 
2025   if (CITraceTypeFlow) {
2026     tty->cr();
2027   }
2028 }
2029 
2030 // ------------------------------------------------------------------
2031 // ciTypeFlow::block_at
2032 //
2033 // Return the block beginning at bci which has a JsrSet compatible
2034 // with jsrs.
2035 ciTypeFlow::Block* ciTypeFlow::block_at(int bci, ciTypeFlow::JsrSet* jsrs, CreateOption option) {
2036   // First find the right ciBlock.
2037   if (CITraceTypeFlow) {
2038     tty->print(">> Requesting block for %d/", bci);
2039     jsrs->print_on(tty);
2040     tty->cr();
2041   }
2042 
2043   ciBlock* ciblk = _methodBlocks->block_containing(bci);
2044   assert(ciblk->start_bci() == bci, "bad ciBlock boundaries");
2045   Block* block = get_block_for(ciblk->index(), jsrs, option);
2046 
2047   assert(block == NULL? (option == no_create): block->is_backedge_copy() == (option == create_backedge_copy), "create option consistent with result");
2048 
2049   if (CITraceTypeFlow) {
2050     if (block != NULL) {
2051       tty->print(">> Found block ");
2052       block->print_value_on(tty);
2053       tty->cr();
2054     } else {
2055       tty->print_cr(">> No such block.");
2056     }
2057   }
2058 
2059   return block;
2060 }
2061 
2062 // ------------------------------------------------------------------
2063 // ciTypeFlow::make_jsr_record
2064 //
2065 // Make a JsrRecord for a given (entry, return) pair, if such a record
2066 // does not already exist.
2067 ciTypeFlow::JsrRecord* ciTypeFlow::make_jsr_record(int entry_address,
2068                                                    int return_address) {
2069   if (_jsr_records == NULL) {
2070     _jsr_records = new (arena()) GrowableArray<JsrRecord*>(arena(),
2071                                                            _jsr_count,
2072                                                            0,
2073                                                            NULL);
2074   }
2075   JsrRecord* record = NULL;
2076   int len = _jsr_records->length();
2077   for (int i = 0; i < len; i++) {
2078     JsrRecord* record = _jsr_records->at(i);
2079     if (record->entry_address() == entry_address &&
2080         record->return_address() == return_address) {
2081       return record;
2082     }
2083   }
2084 
2085   record = new (arena()) JsrRecord(entry_address, return_address);
2086   _jsr_records->append(record);
2087   return record;
2088 }
2089 
2090 // ------------------------------------------------------------------
2091 // ciTypeFlow::flow_exceptions
2092 //
2093 // Merge the current state into all exceptional successors at the
2094 // current point in the code.
2095 void ciTypeFlow::flow_exceptions(GrowableArray<ciTypeFlow::Block*>* exceptions,
2096                                  GrowableArray<ciInstanceKlass*>* exc_klasses,
2097                                  ciTypeFlow::StateVector* state) {
2098   int len = exceptions->length();
2099   assert(exc_klasses->length() == len, "must have same length");
2100   for (int i = 0; i < len; i++) {
2101     Block* block = exceptions->at(i);
2102     ciInstanceKlass* exception_klass = exc_klasses->at(i);
2103 
2104     if (!exception_klass->is_loaded()) {
2105       // Do not compile any code for unloaded exception types.
2106       // Following compiler passes are responsible for doing this also.
2107       continue;
2108     }
2109 
2110     if (block->meet_exception(exception_klass, state)) {
2111       // Block was modified and has PO.  Add it to the work list.
2112       if (block->has_post_order() &&
2113           !block->is_on_work_list()) {
2114         add_to_work_list(block);
2115       }
2116     }
2117   }
2118 }
2119 
2120 // ------------------------------------------------------------------
2121 // ciTypeFlow::flow_successors
2122 //
2123 // Merge the current state into all successors at the current point
2124 // in the code.
2125 void ciTypeFlow::flow_successors(GrowableArray<ciTypeFlow::Block*>* successors,
2126                                  ciTypeFlow::StateVector* state) {
2127   int len = successors->length();
2128   for (int i = 0; i < len; i++) {
2129     Block* block = successors->at(i);
2130     if (block->meet(state)) {
2131       // Block was modified and has PO.  Add it to the work list.
2132       if (block->has_post_order() &&
2133           !block->is_on_work_list()) {
2134         add_to_work_list(block);
2135       }
2136     }
2137   }
2138 }
2139 
2140 // ------------------------------------------------------------------
2141 // ciTypeFlow::can_trap
2142 //
2143 // Tells if a given instruction is able to generate an exception edge.
2144 bool ciTypeFlow::can_trap(ciBytecodeStream& str) {
2145   // Cf. GenerateOopMap::do_exception_edge.
2146   if (!Bytecodes::can_trap(str.cur_bc()))  return false;
2147 
2148   switch (str.cur_bc()) {
2149     // %%% FIXME: ldc of Class can generate an exception
2150     case Bytecodes::_ldc:
2151     case Bytecodes::_ldc_w:
2152     case Bytecodes::_ldc2_w:
2153     case Bytecodes::_aload_0:
2154       // These bytecodes can trap for rewriting.  We need to assume that
2155       // they do not throw exceptions to make the monitor analysis work.
2156       return false;
2157 
2158     case Bytecodes::_ireturn:
2159     case Bytecodes::_lreturn:
2160     case Bytecodes::_freturn:
2161     case Bytecodes::_dreturn:
2162     case Bytecodes::_areturn:
2163     case Bytecodes::_return:
2164       // We can assume the monitor stack is empty in this analysis.
2165       return false;
2166 
2167     case Bytecodes::_monitorexit:
2168       // We can assume monitors are matched in this analysis.
2169       return false;
2170   }
2171 
2172   return true;
2173 }
2174 
2175 // ------------------------------------------------------------------
2176 // ciTypeFlow::clone_loop_heads
2177 //
2178 // Clone the loop heads
2179 bool ciTypeFlow::clone_loop_heads(Loop* lp, StateVector* temp_vector, JsrSet* temp_set) {
2180   bool rslt = false;
2181   for (PreorderLoops iter(loop_tree_root()); !iter.done(); iter.next()) {
2182     lp = iter.current();
2183     Block* head = lp->head();
2184     if (lp == loop_tree_root() ||
2185         lp->is_irreducible() ||
2186         !head->is_clonable_exit(lp))
2187       continue;
2188 
2189     // Avoid BoxLock merge.
2190     if (EliminateNestedLocks && head->has_monitorenter())
2191       continue;
2192 
2193     // check not already cloned
2194     if (head->backedge_copy_count() != 0)
2195       continue;
2196 
2197     // Don't clone head of OSR loop to get correct types in start block.
2198     if (is_osr_flow() && head->start() == start_bci())
2199       continue;
2200 
2201     // check _no_ shared head below us
2202     Loop* ch;
2203     for (ch = lp->child(); ch != NULL && ch->head() != head; ch = ch->sibling());
2204     if (ch != NULL)
2205       continue;
2206 
2207     // Clone head
2208     Block* new_head = head->looping_succ(lp);
2209     Block* clone = clone_loop_head(lp, temp_vector, temp_set);
2210     // Update lp's info
2211     clone->set_loop(lp);
2212     lp->set_head(new_head);
2213     lp->set_tail(clone);
2214     // And move original head into outer loop
2215     head->set_loop(lp->parent());
2216 
2217     rslt = true;
2218   }
2219   return rslt;
2220 }
2221 
2222 // ------------------------------------------------------------------
2223 // ciTypeFlow::clone_loop_head
2224 //
2225 // Clone lp's head and replace tail's successors with clone.
2226 //
2227 //  |
2228 //  v
2229 // head <-> body
2230 //  |
2231 //  v
2232 // exit
2233 //
2234 // new_head
2235 //
2236 //  |
2237 //  v
2238 // head ----------\
2239 //  |             |
2240 //  |             v
2241 //  |  clone <-> body
2242 //  |    |
2243 //  | /--/
2244 //  | |
2245 //  v v
2246 // exit
2247 //
2248 ciTypeFlow::Block* ciTypeFlow::clone_loop_head(Loop* lp, StateVector* temp_vector, JsrSet* temp_set) {
2249   Block* head = lp->head();
2250   Block* tail = lp->tail();
2251   if (CITraceTypeFlow) {
2252     tty->print(">> Requesting clone of loop head "); head->print_value_on(tty);
2253     tty->print("  for predecessor ");                tail->print_value_on(tty);
2254     tty->cr();
2255   }
2256   Block* clone = block_at(head->start(), head->jsrs(), create_backedge_copy);
2257   assert(clone->backedge_copy_count() == 1, "one backedge copy for all back edges");
2258 
2259   assert(!clone->has_pre_order(), "just created");
2260   clone->set_next_pre_order();
2261 
2262   // Insert clone after (orig) tail in reverse post order
2263   clone->set_rpo_next(tail->rpo_next());
2264   tail->set_rpo_next(clone);
2265 
2266   // tail->head becomes tail->clone
2267   for (SuccIter iter(tail); !iter.done(); iter.next()) {
2268     if (iter.succ() == head) {
2269       iter.set_succ(clone);
2270     }
2271   }
2272   flow_block(tail, temp_vector, temp_set);
2273   if (head == tail) {
2274     // For self-loops, clone->head becomes clone->clone
2275     flow_block(clone, temp_vector, temp_set);
2276     for (SuccIter iter(clone); !iter.done(); iter.next()) {
2277       if (iter.succ() == head) {
2278         iter.set_succ(clone);
2279         break;
2280       }
2281     }
2282   }
2283   flow_block(clone, temp_vector, temp_set);
2284 
2285   return clone;
2286 }
2287 
2288 // ------------------------------------------------------------------
2289 // ciTypeFlow::flow_block
2290 //
2291 // Interpret the effects of the bytecodes on the incoming state
2292 // vector of a basic block.  Push the changed state to succeeding
2293 // basic blocks.
2294 void ciTypeFlow::flow_block(ciTypeFlow::Block* block,
2295                             ciTypeFlow::StateVector* state,
2296                             ciTypeFlow::JsrSet* jsrs) {
2297   if (CITraceTypeFlow) {
2298     tty->print("\n>> ANALYZING BLOCK : ");
2299     tty->cr();
2300     block->print_on(tty);
2301   }
2302   assert(block->has_pre_order(), "pre-order is assigned before 1st flow");
2303 
2304   int start = block->start();
2305   int limit = block->limit();
2306   int control = block->control();
2307   if (control != ciBlock::fall_through_bci) {
2308     limit = control;
2309   }
2310 
2311   // Grab the state from the current block.
2312   block->copy_state_into(state);
2313   state->def_locals()->clear();
2314 
2315   GrowableArray<Block*>*           exceptions = block->exceptions();
2316   GrowableArray<ciInstanceKlass*>* exc_klasses = block->exc_klasses();
2317   bool has_exceptions = exceptions->length() > 0;
2318 
2319   bool exceptions_used = false;
2320 
2321   ciBytecodeStream str(method());
2322   str.reset_to_bci(start);
2323   Bytecodes::Code code;
2324   while ((code = str.next()) != ciBytecodeStream::EOBC() &&
2325          str.cur_bci() < limit) {
2326     // Check for exceptional control flow from this point.
2327     if (has_exceptions && can_trap(str)) {
2328       flow_exceptions(exceptions, exc_klasses, state);
2329       exceptions_used = true;
2330     }
2331     // Apply the effects of the current bytecode to our state.
2332     bool res = state->apply_one_bytecode(&str);
2333 
2334     // Watch for bailouts.
2335     if (failing())  return;
2336 
2337     if (str.cur_bc() == Bytecodes::_monitorenter) {
2338       block->set_has_monitorenter();
2339     }
2340 
2341     if (res) {
2342 
2343       // We have encountered a trap.  Record it in this block.
2344       block->set_trap(state->trap_bci(), state->trap_index());
2345 
2346       if (CITraceTypeFlow) {
2347         tty->print_cr(">> Found trap");
2348         block->print_on(tty);
2349       }
2350 
2351       // Save set of locals defined in this block
2352       block->def_locals()->add(state->def_locals());
2353 
2354       // Record (no) successors.
2355       block->successors(&str, state, jsrs);
2356 
2357       assert(!has_exceptions || exceptions_used, "Not removing exceptions");
2358 
2359       // Discontinue interpretation of this Block.
2360       return;
2361     }
2362   }
2363 
2364   GrowableArray<Block*>* successors = NULL;
2365   if (control != ciBlock::fall_through_bci) {
2366     // Check for exceptional control flow from this point.
2367     if (has_exceptions && can_trap(str)) {
2368       flow_exceptions(exceptions, exc_klasses, state);
2369       exceptions_used = true;
2370     }
2371 
2372     // Fix the JsrSet to reflect effect of the bytecode.
2373     block->copy_jsrs_into(jsrs);
2374     jsrs->apply_control(this, &str, state);
2375 
2376     // Find successor edges based on old state and new JsrSet.
2377     successors = block->successors(&str, state, jsrs);
2378 
2379     // Apply the control changes to the state.
2380     state->apply_one_bytecode(&str);
2381   } else {
2382     // Fall through control
2383     successors = block->successors(&str, NULL, NULL);
2384   }
2385 
2386   // Save set of locals defined in this block
2387   block->def_locals()->add(state->def_locals());
2388 
2389   // Remove untaken exception paths
2390   if (!exceptions_used)
2391     exceptions->clear();
2392 
2393   // Pass our state to successors.
2394   flow_successors(successors, state);
2395 }
2396 
2397 // ------------------------------------------------------------------
2398 // ciTypeFlow::PostOrderLoops::next
2399 //
2400 // Advance to next loop tree using a postorder, left-to-right traversal.
2401 void ciTypeFlow::PostorderLoops::next() {
2402   assert(!done(), "must not be done.");
2403   if (_current->sibling() != NULL) {
2404     _current = _current->sibling();
2405     while (_current->child() != NULL) {
2406       _current = _current->child();
2407     }
2408   } else {
2409     _current = _current->parent();
2410   }
2411 }
2412 
2413 // ------------------------------------------------------------------
2414 // ciTypeFlow::PreOrderLoops::next
2415 //
2416 // Advance to next loop tree using a preorder, left-to-right traversal.
2417 void ciTypeFlow::PreorderLoops::next() {
2418   assert(!done(), "must not be done.");
2419   if (_current->child() != NULL) {
2420     _current = _current->child();
2421   } else if (_current->sibling() != NULL) {
2422     _current = _current->sibling();
2423   } else {
2424     while (_current != _root && _current->sibling() == NULL) {
2425       _current = _current->parent();
2426     }
2427     if (_current == _root) {
2428       _current = NULL;
2429       assert(done(), "must be done.");
2430     } else {
2431       assert(_current->sibling() != NULL, "must be more to do");
2432       _current = _current->sibling();
2433     }
2434   }
2435 }
2436 
2437 // ------------------------------------------------------------------
2438 // ciTypeFlow::Loop::sorted_merge
2439 //
2440 // Merge the branch lp into this branch, sorting on the loop head
2441 // pre_orders. Returns the leaf of the merged branch.
2442 // Child and sibling pointers will be setup later.
2443 // Sort is (looking from leaf towards the root)
2444 //  descending on primary key: loop head's pre_order, and
2445 //  ascending  on secondary key: loop tail's pre_order.
2446 ciTypeFlow::Loop* ciTypeFlow::Loop::sorted_merge(Loop* lp) {
2447   Loop* leaf = this;
2448   Loop* prev = NULL;
2449   Loop* current = leaf;
2450   while (lp != NULL) {
2451     int lp_pre_order = lp->head()->pre_order();
2452     // Find insertion point for "lp"
2453     while (current != NULL) {
2454       if (current == lp)
2455         return leaf; // Already in list
2456       if (current->head()->pre_order() < lp_pre_order)
2457         break;
2458       if (current->head()->pre_order() == lp_pre_order &&
2459           current->tail()->pre_order() > lp->tail()->pre_order()) {
2460         break;
2461       }
2462       prev = current;
2463       current = current->parent();
2464     }
2465     Loop* next_lp = lp->parent(); // Save future list of items to insert
2466     // Insert lp before current
2467     lp->set_parent(current);
2468     if (prev != NULL) {
2469       prev->set_parent(lp);
2470     } else {
2471       leaf = lp;
2472     }
2473     prev = lp;     // Inserted item is new prev[ious]
2474     lp = next_lp;  // Next item to insert
2475   }
2476   return leaf;
2477 }
2478 
2479 // ------------------------------------------------------------------
2480 // ciTypeFlow::build_loop_tree
2481 //
2482 // Incrementally build loop tree.
2483 void ciTypeFlow::build_loop_tree(Block* blk) {
2484   assert(!blk->is_post_visited(), "precondition");
2485   Loop* innermost = NULL; // merge of loop tree branches over all successors
2486 
2487   for (SuccIter iter(blk); !iter.done(); iter.next()) {
2488     Loop*  lp   = NULL;
2489     Block* succ = iter.succ();
2490     if (!succ->is_post_visited()) {
2491       // Found backedge since predecessor post visited, but successor is not
2492       assert(succ->pre_order() <= blk->pre_order(), "should be backedge");
2493 
2494       // Create a LoopNode to mark this loop.
2495       lp = new (arena()) Loop(succ, blk);
2496       if (succ->loop() == NULL)
2497         succ->set_loop(lp);
2498       // succ->loop will be updated to innermost loop on a later call, when blk==succ
2499 
2500     } else {  // Nested loop
2501       lp = succ->loop();
2502 
2503       // If succ is loop head, find outer loop.
2504       while (lp != NULL && lp->head() == succ) {
2505         lp = lp->parent();
2506       }
2507       if (lp == NULL) {
2508         // Infinite loop, it's parent is the root
2509         lp = loop_tree_root();
2510       }
2511     }
2512 
2513     // Check for irreducible loop.
2514     // Successor has already been visited. If the successor's loop head
2515     // has already been post-visited, then this is another entry into the loop.
2516     while (lp->head()->is_post_visited() && lp != loop_tree_root()) {
2517       _has_irreducible_entry = true;
2518       lp->set_irreducible(succ);
2519       if (!succ->is_on_work_list()) {
2520         // Assume irreducible entries need more data flow
2521         add_to_work_list(succ);
2522       }
2523       Loop* plp = lp->parent();
2524       if (plp == NULL) {
2525         // This only happens for some irreducible cases.  The parent
2526         // will be updated during a later pass.
2527         break;
2528       }
2529       lp = plp;
2530     }
2531 
2532     // Merge loop tree branch for all successors.
2533     innermost = innermost == NULL ? lp : innermost->sorted_merge(lp);
2534 
2535   } // end loop
2536 
2537   if (innermost == NULL) {
2538     assert(blk->successors()->length() == 0, "CFG exit");
2539     blk->set_loop(loop_tree_root());
2540   } else if (innermost->head() == blk) {
2541     // If loop header, complete the tree pointers
2542     if (blk->loop() != innermost) {
2543 #ifdef ASSERT
2544       assert(blk->loop()->head() == innermost->head(), "same head");
2545       Loop* dl;
2546       for (dl = innermost; dl != NULL && dl != blk->loop(); dl = dl->parent());
2547       assert(dl == blk->loop(), "blk->loop() already in innermost list");
2548 #endif
2549       blk->set_loop(innermost);
2550     }
2551     innermost->def_locals()->add(blk->def_locals());
2552     Loop* l = innermost;
2553     Loop* p = l->parent();
2554     while (p && l->head() == blk) {
2555       l->set_sibling(p->child());  // Put self on parents 'next child'
2556       p->set_child(l);             // Make self the first child of parent
2557       p->def_locals()->add(l->def_locals());
2558       l = p;                       // Walk up the parent chain
2559       p = l->parent();
2560     }
2561   } else {
2562     blk->set_loop(innermost);
2563     innermost->def_locals()->add(blk->def_locals());
2564   }
2565 }
2566 
2567 // ------------------------------------------------------------------
2568 // ciTypeFlow::Loop::contains
2569 //
2570 // Returns true if lp is nested loop.
2571 bool ciTypeFlow::Loop::contains(ciTypeFlow::Loop* lp) const {
2572   assert(lp != NULL, "");
2573   if (this == lp || head() == lp->head()) return true;
2574   int depth1 = depth();
2575   int depth2 = lp->depth();
2576   if (depth1 > depth2)
2577     return false;
2578   while (depth1 < depth2) {
2579     depth2--;
2580     lp = lp->parent();
2581   }
2582   return this == lp;
2583 }
2584 
2585 // ------------------------------------------------------------------
2586 // ciTypeFlow::Loop::depth
2587 //
2588 // Loop depth
2589 int ciTypeFlow::Loop::depth() const {
2590   int dp = 0;
2591   for (Loop* lp = this->parent(); lp != NULL; lp = lp->parent())
2592     dp++;
2593   return dp;
2594 }
2595 
2596 #ifndef PRODUCT
2597 // ------------------------------------------------------------------
2598 // ciTypeFlow::Loop::print
2599 void ciTypeFlow::Loop::print(outputStream* st, int indent) const {
2600   for (int i = 0; i < indent; i++) st->print(" ");
2601   st->print("%d<-%d %s",
2602             is_root() ? 0 : this->head()->pre_order(),
2603             is_root() ? 0 : this->tail()->pre_order(),
2604             is_irreducible()?" irr":"");
2605   st->print(" defs: ");
2606   def_locals()->print_on(st, _head->outer()->method()->max_locals());
2607   st->cr();
2608   for (Loop* ch = child(); ch != NULL; ch = ch->sibling())
2609     ch->print(st, indent+2);
2610 }
2611 #endif
2612 
2613 // ------------------------------------------------------------------
2614 // ciTypeFlow::df_flow_types
2615 //
2616 // Perform the depth first type flow analysis. Helper for flow_types.
2617 void ciTypeFlow::df_flow_types(Block* start,
2618                                bool do_flow,
2619                                StateVector* temp_vector,
2620                                JsrSet* temp_set) {
2621   int dft_len = 100;
2622   GrowableArray<Block*> stk(dft_len);
2623 
2624   ciBlock* dummy = _methodBlocks->make_dummy_block();
2625   JsrSet* root_set = new JsrSet(NULL, 0);
2626   Block* root_head = new (arena()) Block(this, dummy, root_set);
2627   Block* root_tail = new (arena()) Block(this, dummy, root_set);
2628   root_head->set_pre_order(0);
2629   root_head->set_post_order(0);
2630   root_tail->set_pre_order(max_jint);
2631   root_tail->set_post_order(max_jint);
2632   set_loop_tree_root(new (arena()) Loop(root_head, root_tail));
2633 
2634   stk.push(start);
2635 
2636   _next_pre_order = 0;  // initialize pre_order counter
2637   _rpo_list = NULL;
2638   int next_po = 0;      // initialize post_order counter
2639 
2640   // Compute RPO and the control flow graph
2641   int size;
2642   while ((size = stk.length()) > 0) {
2643     Block* blk = stk.top(); // Leave node on stack
2644     if (!blk->is_visited()) {
2645       // forward arc in graph
2646       assert (!blk->has_pre_order(), "");
2647       blk->set_next_pre_order();
2648 
2649       if (_next_pre_order >= MaxNodeLimit / 2) {
2650         // Too many basic blocks.  Bail out.
2651         // This can happen when try/finally constructs are nested to depth N,
2652         // and there is O(2**N) cloning of jsr bodies.  See bug 4697245!
2653         // "MaxNodeLimit / 2" is used because probably the parser will
2654         // generate at least twice that many nodes and bail out.
2655         record_failure("too many basic blocks");
2656         return;
2657       }
2658       if (do_flow) {
2659         flow_block(blk, temp_vector, temp_set);
2660         if (failing()) return; // Watch for bailouts.
2661       }
2662     } else if (!blk->is_post_visited()) {
2663       // cross or back arc
2664       for (SuccIter iter(blk); !iter.done(); iter.next()) {
2665         Block* succ = iter.succ();
2666         if (!succ->is_visited()) {
2667           stk.push(succ);
2668         }
2669       }
2670       if (stk.length() == size) {
2671         // There were no additional children, post visit node now
2672         stk.pop(); // Remove node from stack
2673 
2674         build_loop_tree(blk);
2675         blk->set_post_order(next_po++);   // Assign post order
2676         prepend_to_rpo_list(blk);
2677         assert(blk->is_post_visited(), "");
2678 
2679         if (blk->is_loop_head() && !blk->is_on_work_list()) {
2680           // Assume loop heads need more data flow
2681           add_to_work_list(blk);
2682         }
2683       }
2684     } else {
2685       stk.pop(); // Remove post-visited node from stack
2686     }
2687   }
2688 }
2689 
2690 // ------------------------------------------------------------------
2691 // ciTypeFlow::flow_types
2692 //
2693 // Perform the type flow analysis, creating and cloning Blocks as
2694 // necessary.
2695 void ciTypeFlow::flow_types() {
2696   ResourceMark rm;
2697   StateVector* temp_vector = new StateVector(this);
2698   JsrSet* temp_set = new JsrSet(NULL, 16);
2699 
2700   // Create the method entry block.
2701   Block* start = block_at(start_bci(), temp_set);
2702 
2703   // Load the initial state into it.
2704   const StateVector* start_state = get_start_state();
2705   if (failing())  return;
2706   start->meet(start_state);
2707 
2708   // Depth first visit
2709   df_flow_types(start, true /*do flow*/, temp_vector, temp_set);
2710 
2711   if (failing())  return;
2712   assert(_rpo_list == start, "must be start");
2713 
2714   // Any loops found?
2715   if (loop_tree_root()->child() != NULL &&
2716       env()->comp_level() >= CompLevel_full_optimization) {
2717       // Loop optimizations are not performed on Tier1 compiles.
2718 
2719     bool changed = clone_loop_heads(loop_tree_root(), temp_vector, temp_set);
2720 
2721     // If some loop heads were cloned, recompute postorder and loop tree
2722     if (changed) {
2723       loop_tree_root()->set_child(NULL);
2724       for (Block* blk = _rpo_list; blk != NULL;) {
2725         Block* next = blk->rpo_next();
2726         blk->df_init();
2727         blk = next;
2728       }
2729       df_flow_types(start, false /*no flow*/, temp_vector, temp_set);
2730     }
2731   }
2732 
2733   if (CITraceTypeFlow) {
2734     tty->print_cr("\nLoop tree");
2735     loop_tree_root()->print();
2736   }
2737 
2738   // Continue flow analysis until fixed point reached
2739 
2740   debug_only(int max_block = _next_pre_order;)
2741 
2742   while (!work_list_empty()) {
2743     Block* blk = work_list_next();
2744     assert (blk->has_post_order(), "post order assigned above");
2745 
2746     flow_block(blk, temp_vector, temp_set);
2747 
2748     assert (max_block == _next_pre_order, "no new blocks");
2749     assert (!failing(), "no more bailouts");
2750   }
2751 }
2752 
2753 // ------------------------------------------------------------------
2754 // ciTypeFlow::map_blocks
2755 //
2756 // Create the block map, which indexes blocks in reverse post-order.
2757 void ciTypeFlow::map_blocks() {
2758   assert(_block_map == NULL, "single initialization");
2759   int block_ct = _next_pre_order;
2760   _block_map = NEW_ARENA_ARRAY(arena(), Block*, block_ct);
2761   assert(block_ct == block_count(), "");
2762 
2763   Block* blk = _rpo_list;
2764   for (int m = 0; m < block_ct; m++) {
2765     int rpo = blk->rpo();
2766     assert(rpo == m, "should be sequential");
2767     _block_map[rpo] = blk;
2768     blk = blk->rpo_next();
2769   }
2770   assert(blk == NULL, "should be done");
2771 
2772   for (int j = 0; j < block_ct; j++) {
2773     assert(_block_map[j] != NULL, "must not drop any blocks");
2774     Block* block = _block_map[j];
2775     // Remove dead blocks from successor lists:
2776     for (int e = 0; e <= 1; e++) {
2777       GrowableArray<Block*>* l = e? block->exceptions(): block->successors();
2778       for (int k = 0; k < l->length(); k++) {
2779         Block* s = l->at(k);
2780         if (!s->has_post_order()) {
2781           if (CITraceTypeFlow) {
2782             tty->print("Removing dead %s successor of #%d: ", (e? "exceptional":  "normal"), block->pre_order());
2783             s->print_value_on(tty);
2784             tty->cr();
2785           }
2786           l->remove(s);
2787           --k;
2788         }
2789       }
2790     }
2791   }
2792 }
2793 
2794 // ------------------------------------------------------------------
2795 // ciTypeFlow::get_block_for
2796 //
2797 // Find a block with this ciBlock which has a compatible JsrSet.
2798 // If no such block exists, create it, unless the option is no_create.
2799 // If the option is create_backedge_copy, always create a fresh backedge copy.
2800 ciTypeFlow::Block* ciTypeFlow::get_block_for(int ciBlockIndex, ciTypeFlow::JsrSet* jsrs, CreateOption option) {
2801   Arena* a = arena();
2802   GrowableArray<Block*>* blocks = _idx_to_blocklist[ciBlockIndex];
2803   if (blocks == NULL) {
2804     // Query only?
2805     if (option == no_create)  return NULL;
2806 
2807     // Allocate the growable array.
2808     blocks = new (a) GrowableArray<Block*>(a, 4, 0, NULL);
2809     _idx_to_blocklist[ciBlockIndex] = blocks;
2810   }
2811 
2812   if (option != create_backedge_copy) {
2813     int len = blocks->length();
2814     for (int i = 0; i < len; i++) {
2815       Block* block = blocks->at(i);
2816       if (!block->is_backedge_copy() && block->is_compatible_with(jsrs)) {
2817         return block;
2818       }
2819     }
2820   }
2821 
2822   // Query only?
2823   if (option == no_create)  return NULL;
2824 
2825   // We did not find a compatible block.  Create one.
2826   Block* new_block = new (a) Block(this, _methodBlocks->block(ciBlockIndex), jsrs);
2827   if (option == create_backedge_copy)  new_block->set_backedge_copy(true);
2828   blocks->append(new_block);
2829   return new_block;
2830 }
2831 
2832 // ------------------------------------------------------------------
2833 // ciTypeFlow::backedge_copy_count
2834 //
2835 int ciTypeFlow::backedge_copy_count(int ciBlockIndex, ciTypeFlow::JsrSet* jsrs) const {
2836   GrowableArray<Block*>* blocks = _idx_to_blocklist[ciBlockIndex];
2837 
2838   if (blocks == NULL) {
2839     return 0;
2840   }
2841 
2842   int count = 0;
2843   int len = blocks->length();
2844   for (int i = 0; i < len; i++) {
2845     Block* block = blocks->at(i);
2846     if (block->is_backedge_copy() && block->is_compatible_with(jsrs)) {
2847       count++;
2848     }
2849   }
2850 
2851   return count;
2852 }
2853 
2854 // ------------------------------------------------------------------
2855 // ciTypeFlow::do_flow
2856 //
2857 // Perform type inference flow analysis.
2858 void ciTypeFlow::do_flow() {
2859   if (CITraceTypeFlow) {
2860     tty->print_cr("\nPerforming flow analysis on method");
2861     method()->print();
2862     if (is_osr_flow())  tty->print(" at OSR bci %d", start_bci());
2863     tty->cr();
2864     method()->print_codes();
2865   }
2866   if (CITraceTypeFlow) {
2867     tty->print_cr("Initial CI Blocks");
2868     print_on(tty);
2869   }
2870   flow_types();
2871   // Watch for bailouts.
2872   if (failing()) {
2873     return;
2874   }
2875 
2876   map_blocks();
2877 
2878   if (CIPrintTypeFlow || CITraceTypeFlow) {
2879     rpo_print_on(tty);
2880   }
2881 }
2882 
2883 // ------------------------------------------------------------------
2884 // ciTypeFlow::record_failure()
2885 // The ciTypeFlow object keeps track of failure reasons separately from the ciEnv.
2886 // This is required because there is not a 1-1 relation between the ciEnv and
2887 // the TypeFlow passes within a compilation task.  For example, if the compiler
2888 // is considering inlining a method, it will request a TypeFlow.  If that fails,
2889 // the compilation as a whole may continue without the inlining.  Some TypeFlow
2890 // requests are not optional; if they fail the requestor is responsible for
2891 // copying the failure reason up to the ciEnv.  (See Parse::Parse.)
2892 void ciTypeFlow::record_failure(const char* reason) {
2893   if (env()->log() != NULL) {
2894     env()->log()->elem("failure reason='%s' phase='typeflow'", reason);
2895   }
2896   if (_failure_reason == NULL) {
2897     // Record the first failure reason.
2898     _failure_reason = reason;
2899   }
2900 }
2901 
2902 #ifndef PRODUCT
2903 // ------------------------------------------------------------------
2904 // ciTypeFlow::print_on
2905 void ciTypeFlow::print_on(outputStream* st) const {
2906   // Walk through CI blocks
2907   st->print_cr("********************************************************");
2908   st->print   ("TypeFlow for ");
2909   method()->name()->print_symbol_on(st);
2910   int limit_bci = code_size();
2911   st->print_cr("  %d bytes", limit_bci);
2912   ciMethodBlocks  *mblks = _methodBlocks;
2913   ciBlock* current = NULL;
2914   for (int bci = 0; bci < limit_bci; bci++) {
2915     ciBlock* blk = mblks->block_containing(bci);
2916     if (blk != NULL && blk != current) {
2917       current = blk;
2918       current->print_on(st);
2919 
2920       GrowableArray<Block*>* blocks = _idx_to_blocklist[blk->index()];
2921       int num_blocks = (blocks == NULL) ? 0 : blocks->length();
2922 
2923       if (num_blocks == 0) {
2924         st->print_cr("  No Blocks");
2925       } else {
2926         for (int i = 0; i < num_blocks; i++) {
2927           Block* block = blocks->at(i);
2928           block->print_on(st);
2929         }
2930       }
2931       st->print_cr("--------------------------------------------------------");
2932       st->cr();
2933     }
2934   }
2935   st->print_cr("********************************************************");
2936   st->cr();
2937 }
2938 
2939 void ciTypeFlow::rpo_print_on(outputStream* st) const {
2940   st->print_cr("********************************************************");
2941   st->print   ("TypeFlow for ");
2942   method()->name()->print_symbol_on(st);
2943   int limit_bci = code_size();
2944   st->print_cr("  %d bytes", limit_bci);
2945   for (Block* blk = _rpo_list; blk != NULL; blk = blk->rpo_next()) {
2946     blk->print_on(st);
2947     st->print_cr("--------------------------------------------------------");
2948     st->cr();
2949   }
2950   st->print_cr("********************************************************");
2951   st->cr();
2952 }
2953 #endif