1 /*
   2  * Copyright (c) 2000, 2021, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "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 "memory/resourceArea.hpp"
  39 #include "oops/oop.inline.hpp"
  40 #include "opto/compile.hpp"
  41 #include "opto/node.hpp"
  42 #include "runtime/deoptimization.hpp"
  43 #include "utilities/growableArray.hpp"
  44 
  45 // ciTypeFlow::JsrSet
  46 //
  47 // A JsrSet represents some set of JsrRecords.  This class
  48 // is used to record a set of all jsr routines which we permit
  49 // execution to return (ret) from.
  50 //
  51 // During abstract interpretation, JsrSets are used to determine
  52 // whether two paths which reach a given block are unique, and
  53 // should be cloned apart, or are compatible, and should merge
  54 // together.
  55 
  56 // ------------------------------------------------------------------
  57 // ciTypeFlow::JsrSet::JsrSet
  58 
  59 // Allocate growable array storage in Arena.
  60 ciTypeFlow::JsrSet::JsrSet(Arena* arena, int default_len) : _set(arena, default_len, 0, NULL) {
  61   assert(arena != NULL, "invariant");
  62 }
  63 
  64 // Allocate growable array storage in current ResourceArea.
  65 ciTypeFlow::JsrSet::JsrSet(int default_len) : _set(default_len, 0, NULL) {}
  66 
  67 // ------------------------------------------------------------------
  68 // ciTypeFlow::JsrSet::copy_into
  69 void ciTypeFlow::JsrSet::copy_into(JsrSet* jsrs) {
  70   int len = size();
  71   jsrs->_set.clear();
  72   for (int i = 0; i < len; i++) {
  73     jsrs->_set.append(_set.at(i));
  74   }
  75 }
  76 
  77 // ------------------------------------------------------------------
  78 // ciTypeFlow::JsrSet::is_compatible_with
  79 //
  80 // !!!! MISGIVINGS ABOUT THIS... disregard
  81 //
  82 // Is this JsrSet compatible with some other JsrSet?
  83 //
  84 // In set-theoretic terms, a JsrSet can be viewed as a partial function
  85 // from entry addresses to return addresses.  Two JsrSets A and B are
  86 // compatible iff
  87 //
  88 //   For any x,
  89 //   A(x) defined and B(x) defined implies A(x) == B(x)
  90 //
  91 // Less formally, two JsrSets are compatible when they have identical
  92 // return addresses for any entry addresses they share in common.
  93 bool ciTypeFlow::JsrSet::is_compatible_with(JsrSet* other) {
  94   // Walk through both sets in parallel.  If the same entry address
  95   // appears in both sets, then the return address must match for
  96   // the sets to be compatible.
  97   int size1 = size();
  98   int size2 = other->size();
  99 
 100   // Special case.  If nothing is on the jsr stack, then there can
 101   // be no ret.
 102   if (size2 == 0) {
 103     return true;
 104   } else if (size1 != size2) {
 105     return false;
 106   } else {
 107     for (int i = 0; i < size1; i++) {
 108       JsrRecord* record1 = record_at(i);
 109       JsrRecord* record2 = other->record_at(i);
 110       if (record1->entry_address() != record2->entry_address() ||
 111           record1->return_address() != record2->return_address()) {
 112         return false;
 113       }
 114     }
 115     return true;
 116   }
 117 
 118 #if 0
 119   int pos1 = 0;
 120   int pos2 = 0;
 121   int size1 = size();
 122   int size2 = other->size();
 123   while (pos1 < size1 && pos2 < size2) {
 124     JsrRecord* record1 = record_at(pos1);
 125     JsrRecord* record2 = other->record_at(pos2);
 126     int entry1 = record1->entry_address();
 127     int entry2 = record2->entry_address();
 128     if (entry1 < entry2) {
 129       pos1++;
 130     } else if (entry1 > entry2) {
 131       pos2++;
 132     } else {
 133       if (record1->return_address() == record2->return_address()) {
 134         pos1++;
 135         pos2++;
 136       } else {
 137         // These two JsrSets are incompatible.
 138         return false;
 139       }
 140     }
 141   }
 142   // The two JsrSets agree.
 143   return true;
 144 #endif
 145 }
 146 
 147 // ------------------------------------------------------------------
 148 // ciTypeFlow::JsrSet::insert_jsr_record
 149 //
 150 // Insert the given JsrRecord into the JsrSet, maintaining the order
 151 // of the set and replacing any element with the same entry address.
 152 void ciTypeFlow::JsrSet::insert_jsr_record(JsrRecord* record) {
 153   int len = size();
 154   int entry = record->entry_address();
 155   int pos = 0;
 156   for ( ; pos < len; pos++) {
 157     JsrRecord* current = record_at(pos);
 158     if (entry == current->entry_address()) {
 159       // Stomp over this entry.
 160       _set.at_put(pos, record);
 161       assert(size() == len, "must be same size");
 162       return;
 163     } else if (entry < current->entry_address()) {
 164       break;
 165     }
 166   }
 167 
 168   // Insert the record into the list.
 169   JsrRecord* swap = record;
 170   JsrRecord* temp = NULL;
 171   for ( ; pos < len; pos++) {
 172     temp = _set.at(pos);
 173     _set.at_put(pos, swap);
 174     swap = temp;
 175   }
 176   _set.append(swap);
 177   assert(size() == len+1, "must be larger");
 178 }
 179 
 180 // ------------------------------------------------------------------
 181 // ciTypeFlow::JsrSet::remove_jsr_record
 182 //
 183 // Remove the JsrRecord with the given return address from the JsrSet.
 184 void ciTypeFlow::JsrSet::remove_jsr_record(int return_address) {
 185   int len = size();
 186   for (int i = 0; i < len; i++) {
 187     if (record_at(i)->return_address() == return_address) {
 188       // We have found the proper entry.  Remove it from the
 189       // JsrSet and exit.
 190       for (int j = i + 1; j < len ; j++) {
 191         _set.at_put(j - 1, _set.at(j));
 192       }
 193       _set.trunc_to(len - 1);
 194       assert(size() == len-1, "must be smaller");
 195       return;
 196     }
 197   }
 198   assert(false, "verify: returning from invalid subroutine");
 199 }
 200 
 201 // ------------------------------------------------------------------
 202 // ciTypeFlow::JsrSet::apply_control
 203 //
 204 // Apply the effect of a control-flow bytecode on the JsrSet.  The
 205 // only bytecodes that modify the JsrSet are jsr and ret.
 206 void ciTypeFlow::JsrSet::apply_control(ciTypeFlow* analyzer,
 207                                        ciBytecodeStream* str,
 208                                        ciTypeFlow::StateVector* state) {
 209   Bytecodes::Code code = str->cur_bc();
 210   if (code == Bytecodes::_jsr) {
 211     JsrRecord* record =
 212       analyzer->make_jsr_record(str->get_dest(), str->next_bci());
 213     insert_jsr_record(record);
 214   } else if (code == Bytecodes::_jsr_w) {
 215     JsrRecord* record =
 216       analyzer->make_jsr_record(str->get_far_dest(), str->next_bci());
 217     insert_jsr_record(record);
 218   } else if (code == Bytecodes::_ret) {
 219     Cell local = state->local(str->get_index());
 220     ciType* return_address = state->type_at(local);
 221     assert(return_address->is_return_address(), "verify: wrong type");
 222     if (size() == 0) {
 223       // Ret-state underflow:  Hit a ret w/o any previous jsrs.  Bail out.
 224       // This can happen when a loop is inside a finally clause (4614060).
 225       analyzer->record_failure("OSR in finally clause");
 226       return;
 227     }
 228     remove_jsr_record(return_address->as_return_address()->bci());
 229   }
 230 }
 231 
 232 #ifndef PRODUCT
 233 // ------------------------------------------------------------------
 234 // ciTypeFlow::JsrSet::print_on
 235 void ciTypeFlow::JsrSet::print_on(outputStream* st) const {
 236   st->print("{ ");
 237   int num_elements = size();
 238   if (num_elements > 0) {
 239     int i = 0;
 240     for( ; i < num_elements - 1; i++) {
 241       _set.at(i)->print_on(st);
 242       st->print(", ");
 243     }
 244     _set.at(i)->print_on(st);
 245     st->print(" ");
 246   }
 247   st->print("}");
 248 }
 249 #endif
 250 
 251 // ciTypeFlow::StateVector
 252 //
 253 // A StateVector summarizes the type information at some point in
 254 // the program.
 255 
 256 // ------------------------------------------------------------------
 257 // ciTypeFlow::StateVector::type_meet
 258 //
 259 // Meet two types.
 260 //
 261 // The semi-lattice of types use by this analysis are modeled on those
 262 // of the verifier.  The lattice is as follows:
 263 //
 264 //        top_type() >= all non-extremal types >= bottom_type
 265 //                             and
 266 //   Every primitive type is comparable only with itself.  The meet of
 267 //   reference types is determined by their kind: instance class,
 268 //   interface, or array class.  The meet of two types of the same
 269 //   kind is their least common ancestor.  The meet of two types of
 270 //   different kinds is always java.lang.Object.
 271 ciType* ciTypeFlow::StateVector::type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer) {
 272   assert(t1 != t2, "checked in caller");
 273   if (t1->equals(top_type())) {
 274     return t2;
 275   } else if (t2->equals(top_type())) {
 276     return t1;
 277   } else if (t1->is_primitive_type() || t2->is_primitive_type()) {
 278     // Special case null_type.  null_type meet any reference type T
 279     // is T.  null_type meet null_type is null_type.
 280     if (t1->equals(null_type())) {
 281       if (!t2->is_primitive_type() || t2->equals(null_type())) {
 282         return t2;
 283       }
 284     } else if (t2->equals(null_type())) {
 285       if (!t1->is_primitive_type()) {
 286         return t1;
 287       }
 288     }
 289 
 290     // At least one of the two types is a non-top primitive type.
 291     // The other type is not equal to it.  Fall to bottom.
 292     return bottom_type();
 293   } else {
 294     // Both types are non-top non-primitive types.  That is,
 295     // both types are either instanceKlasses or arrayKlasses.
 296     ciKlass* object_klass = analyzer->env()->Object_klass();
 297     ciKlass* k1 = t1->as_klass();
 298     ciKlass* k2 = t2->as_klass();
 299     if (k1->equals(object_klass) || k2->equals(object_klass)) {
 300       return object_klass;
 301     } else if (!k1->is_loaded() || !k2->is_loaded()) {
 302       // Unloaded classes fall to java.lang.Object at a merge.
 303       return object_klass;
 304     } else if (k1->is_interface() != k2->is_interface()) {
 305       // When an interface meets a non-interface, we get Object;
 306       // This is what the verifier does.
 307       return object_klass;
 308     } else if (k1->is_array_klass() || k2->is_array_klass()) {
 309       // When an array meets a non-array, we get Object.
 310       // When objArray meets typeArray, we also get Object.
 311       // And when typeArray meets different typeArray, we again get Object.
 312       // But when objArray meets objArray, we look carefully at element types.
 313       if (k1->is_obj_array_klass() && k2->is_obj_array_klass()) {
 314         // Meet the element types, then construct the corresponding array type.
 315         ciKlass* elem1 = k1->as_obj_array_klass()->element_klass();
 316         ciKlass* elem2 = k2->as_obj_array_klass()->element_klass();
 317         ciKlass* elem  = type_meet_internal(elem1, elem2, analyzer)->as_klass();
 318         // Do an easy shortcut if one type is a super of the other.
 319         if (elem == elem1) {
 320           assert(k1 == ciObjArrayKlass::make(elem), "shortcut is OK");
 321           return k1;
 322         } else if (elem == elem2) {
 323           assert(k2 == ciObjArrayKlass::make(elem), "shortcut is OK");
 324           return k2;
 325         } else {
 326           return ciObjArrayKlass::make(elem);
 327         }
 328       } else {
 329         return object_klass;
 330       }
 331     } else {
 332       // Must be two plain old instance klasses.
 333       assert(k1->is_instance_klass(), "previous cases handle non-instances");
 334       assert(k2->is_instance_klass(), "previous cases handle non-instances");
 335       return k1->least_common_ancestor(k2);
 336     }
 337   }
 338 }
 339 
 340 
 341 // ------------------------------------------------------------------
 342 // ciTypeFlow::StateVector::StateVector
 343 //
 344 // Build a new state vector
 345 ciTypeFlow::StateVector::StateVector(ciTypeFlow* analyzer) {
 346   _outer = analyzer;
 347   _stack_size = -1;
 348   _monitor_count = -1;
 349   // Allocate the _types array
 350   int max_cells = analyzer->max_cells();
 351   _types = (ciType**)analyzer->arena()->Amalloc(sizeof(ciType*) * max_cells);
 352   for (int i=0; i<max_cells; i++) {
 353     _types[i] = top_type();
 354   }
 355   _trap_bci = -1;
 356   _trap_index = 0;
 357   _def_locals.clear();
 358 }
 359 
 360 
 361 // ------------------------------------------------------------------
 362 // ciTypeFlow::get_start_state
 363 //
 364 // Set this vector to the method entry state.
 365 const ciTypeFlow::StateVector* ciTypeFlow::get_start_state() {
 366   StateVector* state = new StateVector(this);
 367   if (is_osr_flow()) {
 368     ciTypeFlow* non_osr_flow = method()->get_flow_analysis();
 369     if (non_osr_flow->failing()) {
 370       record_failure(non_osr_flow->failure_reason());
 371       return NULL;
 372     }
 373     JsrSet* jsrs = new JsrSet(4);
 374     Block* non_osr_block = non_osr_flow->existing_block_at(start_bci(), jsrs);
 375     if (non_osr_block == NULL) {
 376       record_failure("cannot reach OSR point");
 377       return NULL;
 378     }
 379     // load up the non-OSR state at this point
 380     non_osr_block->copy_state_into(state);
 381     int non_osr_start = non_osr_block->start();
 382     if (non_osr_start != start_bci()) {
 383       // must flow forward from it
 384       if (CITraceTypeFlow) {
 385         tty->print_cr(">> Interpreting pre-OSR block %d:", non_osr_start);
 386       }
 387       Block* block = block_at(non_osr_start, jsrs);
 388       assert(block->limit() == start_bci(), "must flow forward to start");
 389       flow_block(block, state, jsrs);
 390     }
 391     return state;
 392     // Note:  The code below would be an incorrect for an OSR flow,
 393     // even if it were possible for an OSR entry point to be at bci zero.
 394   }
 395   // "Push" the method signature into the first few locals.
 396   state->set_stack_size(-max_locals());
 397   if (!method()->is_static()) {
 398     state->push(method()->holder());
 399     assert(state->tos() == state->local(0), "");
 400   }
 401   for (ciSignatureStream str(method()->signature());
 402        !str.at_return_type();
 403        str.next()) {
 404     state->push_translate(str.type());
 405   }
 406   // Set the rest of the locals to bottom.
 407   Cell cell = state->next_cell(state->tos());
 408   state->set_stack_size(0);
 409   int limit = state->limit_cell();
 410   for (; cell < limit; cell = state->next_cell(cell)) {
 411     state->set_type_at(cell, state->bottom_type());
 412   }
 413   // Lock an object, if necessary.
 414   state->set_monitor_count(method()->is_synchronized() ? 1 : 0);
 415   return state;
 416 }
 417 
 418 // ------------------------------------------------------------------
 419 // ciTypeFlow::StateVector::copy_into
 420 //
 421 // Copy our value into some other StateVector
 422 void ciTypeFlow::StateVector::copy_into(ciTypeFlow::StateVector* copy)
 423 const {
 424   copy->set_stack_size(stack_size());
 425   copy->set_monitor_count(monitor_count());
 426   Cell limit = limit_cell();
 427   for (Cell c = start_cell(); c < limit; c = next_cell(c)) {
 428     copy->set_type_at(c, type_at(c));
 429   }
 430 }
 431 
 432 // ------------------------------------------------------------------
 433 // ciTypeFlow::StateVector::meet
 434 //
 435 // Meets this StateVector with another, destructively modifying this
 436 // one.  Returns true if any modification takes place.
 437 bool ciTypeFlow::StateVector::meet(const ciTypeFlow::StateVector* incoming) {
 438   if (monitor_count() == -1) {
 439     set_monitor_count(incoming->monitor_count());
 440   }
 441   assert(monitor_count() == incoming->monitor_count(), "monitors must match");
 442 
 443   if (stack_size() == -1) {
 444     set_stack_size(incoming->stack_size());
 445     Cell limit = limit_cell();
 446     #ifdef ASSERT
 447     { for (Cell c = start_cell(); c < limit; c = next_cell(c)) {
 448         assert(type_at(c) == top_type(), "");
 449     } }
 450     #endif
 451     // Make a simple copy of the incoming state.
 452     for (Cell c = start_cell(); c < limit; c = next_cell(c)) {
 453       set_type_at(c, incoming->type_at(c));
 454     }
 455     return true;  // it is always different the first time
 456   }
 457 #ifdef ASSERT
 458   if (stack_size() != incoming->stack_size()) {
 459     _outer->method()->print_codes();
 460     tty->print_cr("!!!! Stack size conflict");
 461     tty->print_cr("Current state:");
 462     print_on(tty);
 463     tty->print_cr("Incoming state:");
 464     ((StateVector*)incoming)->print_on(tty);
 465   }
 466 #endif
 467   assert(stack_size() == incoming->stack_size(), "sanity");
 468 
 469   bool different = false;
 470   Cell limit = limit_cell();
 471   for (Cell c = start_cell(); c < limit; c = next_cell(c)) {
 472     ciType* t1 = type_at(c);
 473     ciType* t2 = incoming->type_at(c);
 474     if (!t1->equals(t2)) {
 475       ciType* new_type = type_meet(t1, t2);
 476       if (!t1->equals(new_type)) {
 477         set_type_at(c, new_type);
 478         different = true;
 479       }
 480     }
 481   }
 482   return different;
 483 }
 484 
 485 // ------------------------------------------------------------------
 486 // ciTypeFlow::StateVector::meet_exception
 487 //
 488 // Meets this StateVector with another, destructively modifying this
 489 // one.  The incoming state is coming via an exception.  Returns true
 490 // if any modification takes place.
 491 bool ciTypeFlow::StateVector::meet_exception(ciInstanceKlass* exc,
 492                                      const ciTypeFlow::StateVector* incoming) {
 493   if (monitor_count() == -1) {
 494     set_monitor_count(incoming->monitor_count());
 495   }
 496   assert(monitor_count() == incoming->monitor_count(), "monitors must match");
 497 
 498   if (stack_size() == -1) {
 499     set_stack_size(1);
 500   }
 501 
 502   assert(stack_size() ==  1, "must have one-element stack");
 503 
 504   bool different = false;
 505 
 506   // Meet locals from incoming array.
 507   Cell limit = local(_outer->max_locals()-1);
 508   for (Cell c = start_cell(); c <= limit; c = next_cell(c)) {
 509     ciType* t1 = type_at(c);
 510     ciType* t2 = incoming->type_at(c);
 511     if (!t1->equals(t2)) {
 512       ciType* new_type = type_meet(t1, t2);
 513       if (!t1->equals(new_type)) {
 514         set_type_at(c, new_type);
 515         different = true;
 516       }
 517     }
 518   }
 519 
 520   // Handle stack separately.  When an exception occurs, the
 521   // only stack entry is the exception instance.
 522   ciType* tos_type = type_at_tos();
 523   if (!tos_type->equals(exc)) {
 524     ciType* new_type = type_meet(tos_type, exc);
 525     if (!tos_type->equals(new_type)) {
 526       set_type_at_tos(new_type);
 527       different = true;
 528     }
 529   }
 530 
 531   return different;
 532 }
 533 
 534 // ------------------------------------------------------------------
 535 // ciTypeFlow::StateVector::push_translate
 536 void ciTypeFlow::StateVector::push_translate(ciType* type) {
 537   BasicType basic_type = type->basic_type();
 538   if (basic_type == T_BOOLEAN || basic_type == T_CHAR ||
 539       basic_type == T_BYTE    || basic_type == T_SHORT) {
 540     push_int();
 541   } else {
 542     push(type);
 543     if (type->is_two_word()) {
 544       push(half_type(type));
 545     }
 546   }
 547 }
 548 
 549 // ------------------------------------------------------------------
 550 // ciTypeFlow::StateVector::do_aaload
 551 void ciTypeFlow::StateVector::do_aaload(ciBytecodeStream* str) {
 552   pop_int();
 553   ciObjArrayKlass* array_klass = pop_objArray();
 554   if (array_klass == NULL) {
 555     // Did aaload on a null reference; push a null and ignore the exception.
 556     // This instruction will never continue normally.  All we have to do
 557     // is report a value that will meet correctly with any downstream
 558     // reference types on paths that will truly be executed.  This null type
 559     // meets with any reference type to yield that same reference type.
 560     // (The compiler will generate an unconditional exception here.)
 561     push(null_type());
 562     return;
 563   }
 564   if (!array_klass->is_loaded()) {
 565     // Only fails for some -Xcomp runs
 566     trap(str, array_klass,
 567          Deoptimization::make_trap_request
 568          (Deoptimization::Reason_unloaded,
 569           Deoptimization::Action_reinterpret));
 570     return;
 571   }
 572   ciKlass* element_klass = array_klass->element_klass();
 573   if (!element_klass->is_loaded() && element_klass->is_instance_klass()) {
 574     Untested("unloaded array element class in ciTypeFlow");
 575     trap(str, element_klass,
 576          Deoptimization::make_trap_request
 577          (Deoptimization::Reason_unloaded,
 578           Deoptimization::Action_reinterpret));
 579   } else {
 580     push_object(element_klass);
 581   }
 582 }
 583 
 584 
 585 // ------------------------------------------------------------------
 586 // ciTypeFlow::StateVector::do_checkcast
 587 void ciTypeFlow::StateVector::do_checkcast(ciBytecodeStream* str) {
 588   bool will_link;
 589   ciKlass* klass = str->get_klass(will_link);
 590   if (!will_link) {
 591     // VM's interpreter will not load 'klass' if object is NULL.
 592     // Type flow after this block may still be needed in two situations:
 593     // 1) C2 uses do_null_assert() and continues compilation for later blocks
 594     // 2) C2 does an OSR compile in a later block (see bug 4778368).
 595     pop_object();
 596     do_null_assert(klass);
 597   } else {
 598     pop_object();
 599     push_object(klass);
 600   }
 601 }
 602 
 603 // ------------------------------------------------------------------
 604 // ciTypeFlow::StateVector::do_getfield
 605 void ciTypeFlow::StateVector::do_getfield(ciBytecodeStream* str) {
 606   // could add assert here for type of object.
 607   pop_object();
 608   do_getstatic(str);
 609 }
 610 
 611 // ------------------------------------------------------------------
 612 // ciTypeFlow::StateVector::do_getstatic
 613 void ciTypeFlow::StateVector::do_getstatic(ciBytecodeStream* str) {
 614   bool will_link;
 615   ciField* field = str->get_field(will_link);
 616   if (!will_link) {
 617     trap(str, field->holder(), str->get_field_holder_index());
 618   } else {
 619     ciType* field_type = field->type();
 620     if (!field_type->is_loaded()) {
 621       // Normally, we need the field's type to be loaded if we are to
 622       // do anything interesting with its value.
 623       // We used to do this:  trap(str, str->get_field_signature_index());
 624       //
 625       // There is one good reason not to trap here.  Execution can
 626       // get past this "getfield" or "getstatic" if the value of
 627       // the field is null.  As long as the value is null, the class
 628       // does not need to be loaded!  The compiler must assume that
 629       // the value of the unloaded class reference is null; if the code
 630       // ever sees a non-null value, loading has occurred.
 631       //
 632       // This actually happens often enough to be annoying.  If the
 633       // compiler throws an uncommon trap at this bytecode, you can
 634       // get an endless loop of recompilations, when all the code
 635       // needs to do is load a series of null values.  Also, a trap
 636       // here can make an OSR entry point unreachable, triggering the
 637       // assert on non_osr_block in ciTypeFlow::get_start_state.
 638       // (See bug 4379915.)
 639       do_null_assert(field_type->as_klass());
 640     } else {
 641       push_translate(field_type);
 642     }
 643   }
 644 }
 645 
 646 // ------------------------------------------------------------------
 647 // ciTypeFlow::StateVector::do_invoke
 648 void ciTypeFlow::StateVector::do_invoke(ciBytecodeStream* str,
 649                                         bool has_receiver) {
 650   bool will_link;
 651   ciSignature* declared_signature = NULL;
 652   ciMethod* callee = str->get_method(will_link, &declared_signature);
 653   assert(declared_signature != NULL, "cannot be null");
 654   if (!will_link) {
 655     // We weren't able to find the method.
 656     if (str->cur_bc() == Bytecodes::_invokedynamic) {
 657       trap(str, NULL,
 658            Deoptimization::make_trap_request
 659            (Deoptimization::Reason_uninitialized,
 660             Deoptimization::Action_reinterpret));
 661     } else {
 662       ciKlass* unloaded_holder = callee->holder();
 663       trap(str, unloaded_holder, str->get_method_holder_index());
 664     }
 665   } else {
 666     // We are using the declared signature here because it might be
 667     // different from the callee signature (Cf. invokedynamic and
 668     // invokehandle).
 669     ciSignatureStream sigstr(declared_signature);
 670     const int arg_size = declared_signature->size();
 671     const int stack_base = stack_size() - arg_size;
 672     int i = 0;
 673     for( ; !sigstr.at_return_type(); sigstr.next()) {
 674       ciType* type = sigstr.type();
 675       ciType* stack_type = type_at(stack(stack_base + i++));
 676       // Do I want to check this type?
 677       // assert(stack_type->is_subtype_of(type), "bad type for field value");
 678       if (type->is_two_word()) {
 679         ciType* stack_type2 = type_at(stack(stack_base + i++));
 680         assert(stack_type2->equals(half_type(type)), "must be 2nd half");
 681       }
 682     }
 683     assert(arg_size == i, "must match");
 684     for (int j = 0; j < arg_size; j++) {
 685       pop();
 686     }
 687     if (has_receiver) {
 688       // Check this?
 689       pop_object();
 690     }
 691     assert(!sigstr.is_done(), "must have return type");
 692     ciType* return_type = sigstr.type();
 693     if (!return_type->is_void()) {
 694       if (!return_type->is_loaded()) {
 695         // As in do_getstatic(), generally speaking, we need the return type to
 696         // be loaded if we are to do anything interesting with its value.
 697         // We used to do this:  trap(str, str->get_method_signature_index());
 698         //
 699         // We do not trap here since execution can get past this invoke if
 700         // the return value is null.  As long as the value is null, the class
 701         // does not need to be loaded!  The compiler must assume that
 702         // the value of the unloaded class reference is null; if the code
 703         // ever sees a non-null value, loading has occurred.
 704         //
 705         // See do_getstatic() for similar explanation, as well as bug 4684993.
 706         do_null_assert(return_type->as_klass());
 707       } else {
 708         push_translate(return_type);
 709       }
 710     }
 711   }
 712 }
 713 
 714 // ------------------------------------------------------------------
 715 // ciTypeFlow::StateVector::do_jsr
 716 void ciTypeFlow::StateVector::do_jsr(ciBytecodeStream* str) {
 717   push(ciReturnAddress::make(str->next_bci()));
 718 }
 719 
 720 // ------------------------------------------------------------------
 721 // ciTypeFlow::StateVector::do_ldc
 722 void ciTypeFlow::StateVector::do_ldc(ciBytecodeStream* str) {
 723   ciConstant con = str->get_constant();
 724   if (con.is_valid()) {
 725     BasicType basic_type = con.basic_type();
 726     if (is_reference_type(basic_type)) {
 727       ciObject* obj = con.as_object();
 728       if (obj->is_null_object()) {
 729         push_null();
 730       } else {
 731         assert(obj->is_instance() || obj->is_array(), "must be java_mirror of klass");
 732         push_object(obj->klass());
 733       }
 734     } else {
 735       push_translate(ciType::make(basic_type));
 736     }
 737   } else {
 738     if (str->is_unresolved_klass_in_error()) {
 739       trap(str, NULL, Deoptimization::make_trap_request(Deoptimization::Reason_unhandled,
 740                                                         Deoptimization::Action_none));
 741     } else {
 742       // OutOfMemoryError in the CI while loading constant
 743       push_null();
 744       outer()->record_failure("ldc did not link");
 745     }
 746   }
 747 }
 748 
 749 // ------------------------------------------------------------------
 750 // ciTypeFlow::StateVector::do_multianewarray
 751 void ciTypeFlow::StateVector::do_multianewarray(ciBytecodeStream* str) {
 752   int dimensions = str->get_dimensions();
 753   bool will_link;
 754   ciArrayKlass* array_klass = str->get_klass(will_link)->as_array_klass();
 755   if (!will_link) {
 756     trap(str, array_klass, str->get_klass_index());
 757   } else {
 758     for (int i = 0; i < dimensions; i++) {
 759       pop_int();
 760     }
 761     push_object(array_klass);
 762   }
 763 }
 764 
 765 // ------------------------------------------------------------------
 766 // ciTypeFlow::StateVector::do_new
 767 void ciTypeFlow::StateVector::do_new(ciBytecodeStream* str) {
 768   bool will_link;
 769   ciKlass* klass = str->get_klass(will_link);
 770   if (!will_link || str->is_unresolved_klass()) {
 771     trap(str, klass, str->get_klass_index());
 772   } else {
 773     push_object(klass);
 774   }
 775 }
 776 
 777 // ------------------------------------------------------------------
 778 // ciTypeFlow::StateVector::do_newarray
 779 void ciTypeFlow::StateVector::do_newarray(ciBytecodeStream* str) {
 780   pop_int();
 781   ciKlass* klass = ciTypeArrayKlass::make((BasicType)str->get_index());
 782   push_object(klass);
 783 }
 784 
 785 // ------------------------------------------------------------------
 786 // ciTypeFlow::StateVector::do_putfield
 787 void ciTypeFlow::StateVector::do_putfield(ciBytecodeStream* str) {
 788   do_putstatic(str);
 789   if (_trap_bci != -1)  return;  // unloaded field holder, etc.
 790   // could add assert here for type of object.
 791   pop_object();
 792 }
 793 
 794 // ------------------------------------------------------------------
 795 // ciTypeFlow::StateVector::do_putstatic
 796 void ciTypeFlow::StateVector::do_putstatic(ciBytecodeStream* str) {
 797   bool will_link;
 798   ciField* field = str->get_field(will_link);
 799   if (!will_link) {
 800     trap(str, field->holder(), str->get_field_holder_index());
 801   } else {
 802     ciType* field_type = field->type();
 803     ciType* type = pop_value();
 804     // Do I want to check this type?
 805     //      assert(type->is_subtype_of(field_type), "bad type for field value");
 806     if (field_type->is_two_word()) {
 807       ciType* type2 = pop_value();
 808       assert(type2->is_two_word(), "must be 2nd half");
 809       assert(type == half_type(type2), "must be 2nd half");
 810     }
 811   }
 812 }
 813 
 814 // ------------------------------------------------------------------
 815 // ciTypeFlow::StateVector::do_ret
 816 void ciTypeFlow::StateVector::do_ret(ciBytecodeStream* str) {
 817   Cell index = local(str->get_index());
 818 
 819   ciType* address = type_at(index);
 820   assert(address->is_return_address(), "bad return address");
 821   set_type_at(index, bottom_type());
 822 }
 823 
 824 // ------------------------------------------------------------------
 825 // ciTypeFlow::StateVector::trap
 826 //
 827 // Stop interpretation of this path with a trap.
 828 void ciTypeFlow::StateVector::trap(ciBytecodeStream* str, ciKlass* klass, int index) {
 829   _trap_bci = str->cur_bci();
 830   _trap_index = index;
 831 
 832   // Log information about this trap:
 833   CompileLog* log = outer()->env()->log();
 834   if (log != NULL) {
 835     int mid = log->identify(outer()->method());
 836     int kid = (klass == NULL)? -1: log->identify(klass);
 837     log->begin_elem("uncommon_trap method='%d' bci='%d'", mid, str->cur_bci());
 838     char buf[100];
 839     log->print(" %s", Deoptimization::format_trap_request(buf, sizeof(buf),
 840                                                           index));
 841     if (kid >= 0)
 842       log->print(" klass='%d'", kid);
 843     log->end_elem();
 844   }
 845 }
 846 
 847 // ------------------------------------------------------------------
 848 // ciTypeFlow::StateVector::do_null_assert
 849 // Corresponds to graphKit::do_null_assert.
 850 void ciTypeFlow::StateVector::do_null_assert(ciKlass* unloaded_klass) {
 851   if (unloaded_klass->is_loaded()) {
 852     // We failed to link, but we can still compute with this class,
 853     // since it is loaded somewhere.  The compiler will uncommon_trap
 854     // if the object is not null, but the typeflow pass can not assume
 855     // that the object will be null, otherwise it may incorrectly tell
 856     // the parser that an object is known to be null. 4761344, 4807707
 857     push_object(unloaded_klass);
 858   } else {
 859     // The class is not loaded anywhere.  It is safe to model the
 860     // null in the typestates, because we can compile in a null check
 861     // which will deoptimize us if someone manages to load the
 862     // class later.
 863     push_null();
 864   }
 865 }
 866 
 867 
 868 // ------------------------------------------------------------------
 869 // ciTypeFlow::StateVector::apply_one_bytecode
 870 //
 871 // Apply the effect of one bytecode to this StateVector
 872 bool ciTypeFlow::StateVector::apply_one_bytecode(ciBytecodeStream* str) {
 873   _trap_bci = -1;
 874   _trap_index = 0;
 875 
 876   if (CITraceTypeFlow) {
 877     tty->print_cr(">> Interpreting bytecode %d:%s", str->cur_bci(),
 878                   Bytecodes::name(str->cur_bc()));
 879   }
 880 
 881   switch(str->cur_bc()) {
 882   case Bytecodes::_aaload: do_aaload(str);                       break;
 883 
 884   case Bytecodes::_aastore:
 885     {
 886       pop_object();
 887       pop_int();
 888       pop_objArray();
 889       break;
 890     }
 891   case Bytecodes::_aconst_null:
 892     {
 893       push_null();
 894       break;
 895     }
 896   case Bytecodes::_aload:   load_local_object(str->get_index());    break;
 897   case Bytecodes::_aload_0: load_local_object(0);                   break;
 898   case Bytecodes::_aload_1: load_local_object(1);                   break;
 899   case Bytecodes::_aload_2: load_local_object(2);                   break;
 900   case Bytecodes::_aload_3: load_local_object(3);                   break;
 901 
 902   case Bytecodes::_anewarray:
 903     {
 904       pop_int();
 905       bool will_link;
 906       ciKlass* element_klass = str->get_klass(will_link);
 907       if (!will_link) {
 908         trap(str, element_klass, str->get_klass_index());
 909       } else {
 910         push_object(ciObjArrayKlass::make(element_klass));
 911       }
 912       break;
 913     }
 914   case Bytecodes::_areturn:
 915   case Bytecodes::_ifnonnull:
 916   case Bytecodes::_ifnull:
 917     {
 918       pop_object();
 919       break;
 920     }
 921   case Bytecodes::_monitorenter:
 922     {
 923       pop_object();
 924       set_monitor_count(monitor_count() + 1);
 925       break;
 926     }
 927   case Bytecodes::_monitorexit:
 928     {
 929       pop_object();
 930       assert(monitor_count() > 0, "must be a monitor to exit from");
 931       set_monitor_count(monitor_count() - 1);
 932       break;
 933     }
 934   case Bytecodes::_arraylength:
 935     {
 936       pop_array();
 937       push_int();
 938       break;
 939     }
 940   case Bytecodes::_astore:   store_local_object(str->get_index());  break;
 941   case Bytecodes::_astore_0: store_local_object(0);                 break;
 942   case Bytecodes::_astore_1: store_local_object(1);                 break;
 943   case Bytecodes::_astore_2: store_local_object(2);                 break;
 944   case Bytecodes::_astore_3: store_local_object(3);                 break;
 945 
 946   case Bytecodes::_athrow:
 947     {
 948       NEEDS_CLEANUP;
 949       pop_object();
 950       break;
 951     }
 952   case Bytecodes::_baload:
 953   case Bytecodes::_caload:
 954   case Bytecodes::_iaload:
 955   case Bytecodes::_saload:
 956     {
 957       pop_int();
 958       ciTypeArrayKlass* array_klass = pop_typeArray();
 959       // Put assert here for right type?
 960       push_int();
 961       break;
 962     }
 963   case Bytecodes::_bastore:
 964   case Bytecodes::_castore:
 965   case Bytecodes::_iastore:
 966   case Bytecodes::_sastore:
 967     {
 968       pop_int();
 969       pop_int();
 970       pop_typeArray();
 971       // assert here?
 972       break;
 973     }
 974   case Bytecodes::_bipush:
 975   case Bytecodes::_iconst_m1:
 976   case Bytecodes::_iconst_0:
 977   case Bytecodes::_iconst_1:
 978   case Bytecodes::_iconst_2:
 979   case Bytecodes::_iconst_3:
 980   case Bytecodes::_iconst_4:
 981   case Bytecodes::_iconst_5:
 982   case Bytecodes::_sipush:
 983     {
 984       push_int();
 985       break;
 986     }
 987   case Bytecodes::_checkcast: do_checkcast(str);                  break;
 988 
 989   case Bytecodes::_d2f:
 990     {
 991       pop_double();
 992       push_float();
 993       break;
 994     }
 995   case Bytecodes::_d2i:
 996     {
 997       pop_double();
 998       push_int();
 999       break;
1000     }
1001   case Bytecodes::_d2l:
1002     {
1003       pop_double();
1004       push_long();
1005       break;
1006     }
1007   case Bytecodes::_dadd:
1008   case Bytecodes::_ddiv:
1009   case Bytecodes::_dmul:
1010   case Bytecodes::_drem:
1011   case Bytecodes::_dsub:
1012     {
1013       pop_double();
1014       pop_double();
1015       push_double();
1016       break;
1017     }
1018   case Bytecodes::_daload:
1019     {
1020       pop_int();
1021       ciTypeArrayKlass* array_klass = pop_typeArray();
1022       // Put assert here for right type?
1023       push_double();
1024       break;
1025     }
1026   case Bytecodes::_dastore:
1027     {
1028       pop_double();
1029       pop_int();
1030       pop_typeArray();
1031       // assert here?
1032       break;
1033     }
1034   case Bytecodes::_dcmpg:
1035   case Bytecodes::_dcmpl:
1036     {
1037       pop_double();
1038       pop_double();
1039       push_int();
1040       break;
1041     }
1042   case Bytecodes::_dconst_0:
1043   case Bytecodes::_dconst_1:
1044     {
1045       push_double();
1046       break;
1047     }
1048   case Bytecodes::_dload:   load_local_double(str->get_index());    break;
1049   case Bytecodes::_dload_0: load_local_double(0);                   break;
1050   case Bytecodes::_dload_1: load_local_double(1);                   break;
1051   case Bytecodes::_dload_2: load_local_double(2);                   break;
1052   case Bytecodes::_dload_3: load_local_double(3);                   break;
1053 
1054   case Bytecodes::_dneg:
1055     {
1056       pop_double();
1057       push_double();
1058       break;
1059     }
1060   case Bytecodes::_dreturn:
1061     {
1062       pop_double();
1063       break;
1064     }
1065   case Bytecodes::_dstore:   store_local_double(str->get_index());  break;
1066   case Bytecodes::_dstore_0: store_local_double(0);                 break;
1067   case Bytecodes::_dstore_1: store_local_double(1);                 break;
1068   case Bytecodes::_dstore_2: store_local_double(2);                 break;
1069   case Bytecodes::_dstore_3: store_local_double(3);                 break;
1070 
1071   case Bytecodes::_dup:
1072     {
1073       push(type_at_tos());
1074       break;
1075     }
1076   case Bytecodes::_dup_x1:
1077     {
1078       ciType* value1 = pop_value();
1079       ciType* value2 = pop_value();
1080       push(value1);
1081       push(value2);
1082       push(value1);
1083       break;
1084     }
1085   case Bytecodes::_dup_x2:
1086     {
1087       ciType* value1 = pop_value();
1088       ciType* value2 = pop_value();
1089       ciType* value3 = pop_value();
1090       push(value1);
1091       push(value3);
1092       push(value2);
1093       push(value1);
1094       break;
1095     }
1096   case Bytecodes::_dup2:
1097     {
1098       ciType* value1 = pop_value();
1099       ciType* value2 = pop_value();
1100       push(value2);
1101       push(value1);
1102       push(value2);
1103       push(value1);
1104       break;
1105     }
1106   case Bytecodes::_dup2_x1:
1107     {
1108       ciType* value1 = pop_value();
1109       ciType* value2 = pop_value();
1110       ciType* value3 = pop_value();
1111       push(value2);
1112       push(value1);
1113       push(value3);
1114       push(value2);
1115       push(value1);
1116       break;
1117     }
1118   case Bytecodes::_dup2_x2:
1119     {
1120       ciType* value1 = pop_value();
1121       ciType* value2 = pop_value();
1122       ciType* value3 = pop_value();
1123       ciType* value4 = pop_value();
1124       push(value2);
1125       push(value1);
1126       push(value4);
1127       push(value3);
1128       push(value2);
1129       push(value1);
1130       break;
1131     }
1132   case Bytecodes::_f2d:
1133     {
1134       pop_float();
1135       push_double();
1136       break;
1137     }
1138   case Bytecodes::_f2i:
1139     {
1140       pop_float();
1141       push_int();
1142       break;
1143     }
1144   case Bytecodes::_f2l:
1145     {
1146       pop_float();
1147       push_long();
1148       break;
1149     }
1150   case Bytecodes::_fadd:
1151   case Bytecodes::_fdiv:
1152   case Bytecodes::_fmul:
1153   case Bytecodes::_frem:
1154   case Bytecodes::_fsub:
1155     {
1156       pop_float();
1157       pop_float();
1158       push_float();
1159       break;
1160     }
1161   case Bytecodes::_faload:
1162     {
1163       pop_int();
1164       ciTypeArrayKlass* array_klass = pop_typeArray();
1165       // Put assert here.
1166       push_float();
1167       break;
1168     }
1169   case Bytecodes::_fastore:
1170     {
1171       pop_float();
1172       pop_int();
1173       ciTypeArrayKlass* array_klass = pop_typeArray();
1174       // Put assert here.
1175       break;
1176     }
1177   case Bytecodes::_fcmpg:
1178   case Bytecodes::_fcmpl:
1179     {
1180       pop_float();
1181       pop_float();
1182       push_int();
1183       break;
1184     }
1185   case Bytecodes::_fconst_0:
1186   case Bytecodes::_fconst_1:
1187   case Bytecodes::_fconst_2:
1188     {
1189       push_float();
1190       break;
1191     }
1192   case Bytecodes::_fload:   load_local_float(str->get_index());     break;
1193   case Bytecodes::_fload_0: load_local_float(0);                    break;
1194   case Bytecodes::_fload_1: load_local_float(1);                    break;
1195   case Bytecodes::_fload_2: load_local_float(2);                    break;
1196   case Bytecodes::_fload_3: load_local_float(3);                    break;
1197 
1198   case Bytecodes::_fneg:
1199     {
1200       pop_float();
1201       push_float();
1202       break;
1203     }
1204   case Bytecodes::_freturn:
1205     {
1206       pop_float();
1207       break;
1208     }
1209   case Bytecodes::_fstore:    store_local_float(str->get_index());   break;
1210   case Bytecodes::_fstore_0:  store_local_float(0);                  break;
1211   case Bytecodes::_fstore_1:  store_local_float(1);                  break;
1212   case Bytecodes::_fstore_2:  store_local_float(2);                  break;
1213   case Bytecodes::_fstore_3:  store_local_float(3);                  break;
1214 
1215   case Bytecodes::_getfield:  do_getfield(str);                      break;
1216   case Bytecodes::_getstatic: do_getstatic(str);                     break;
1217 
1218   case Bytecodes::_goto:
1219   case Bytecodes::_goto_w:
1220   case Bytecodes::_nop:
1221   case Bytecodes::_return:
1222     {
1223       // do nothing.
1224       break;
1225     }
1226   case Bytecodes::_i2b:
1227   case Bytecodes::_i2c:
1228   case Bytecodes::_i2s:
1229   case Bytecodes::_ineg:
1230     {
1231       pop_int();
1232       push_int();
1233       break;
1234     }
1235   case Bytecodes::_i2d:
1236     {
1237       pop_int();
1238       push_double();
1239       break;
1240     }
1241   case Bytecodes::_i2f:
1242     {
1243       pop_int();
1244       push_float();
1245       break;
1246     }
1247   case Bytecodes::_i2l:
1248     {
1249       pop_int();
1250       push_long();
1251       break;
1252     }
1253   case Bytecodes::_iadd:
1254   case Bytecodes::_iand:
1255   case Bytecodes::_idiv:
1256   case Bytecodes::_imul:
1257   case Bytecodes::_ior:
1258   case Bytecodes::_irem:
1259   case Bytecodes::_ishl:
1260   case Bytecodes::_ishr:
1261   case Bytecodes::_isub:
1262   case Bytecodes::_iushr:
1263   case Bytecodes::_ixor:
1264     {
1265       pop_int();
1266       pop_int();
1267       push_int();
1268       break;
1269     }
1270   case Bytecodes::_if_acmpeq:
1271   case Bytecodes::_if_acmpne:
1272     {
1273       pop_object();
1274       pop_object();
1275       break;
1276     }
1277   case Bytecodes::_if_icmpeq:
1278   case Bytecodes::_if_icmpge:
1279   case Bytecodes::_if_icmpgt:
1280   case Bytecodes::_if_icmple:
1281   case Bytecodes::_if_icmplt:
1282   case Bytecodes::_if_icmpne:
1283     {
1284       pop_int();
1285       pop_int();
1286       break;
1287     }
1288   case Bytecodes::_ifeq:
1289   case Bytecodes::_ifle:
1290   case Bytecodes::_iflt:
1291   case Bytecodes::_ifge:
1292   case Bytecodes::_ifgt:
1293   case Bytecodes::_ifne:
1294   case Bytecodes::_ireturn:
1295   case Bytecodes::_lookupswitch:
1296   case Bytecodes::_tableswitch:
1297     {
1298       pop_int();
1299       break;
1300     }
1301   case Bytecodes::_iinc:
1302     {
1303       int lnum = str->get_index();
1304       check_int(local(lnum));
1305       store_to_local(lnum);
1306       break;
1307     }
1308   case Bytecodes::_iload:   load_local_int(str->get_index()); break;
1309   case Bytecodes::_iload_0: load_local_int(0);                      break;
1310   case Bytecodes::_iload_1: load_local_int(1);                      break;
1311   case Bytecodes::_iload_2: load_local_int(2);                      break;
1312   case Bytecodes::_iload_3: load_local_int(3);                      break;
1313 
1314   case Bytecodes::_instanceof:
1315     {
1316       // Check for uncommon trap:
1317       do_checkcast(str);
1318       pop_object();
1319       push_int();
1320       break;
1321     }
1322   case Bytecodes::_invokeinterface: do_invoke(str, true);           break;
1323   case Bytecodes::_invokespecial:   do_invoke(str, true);           break;
1324   case Bytecodes::_invokestatic:    do_invoke(str, false);          break;
1325   case Bytecodes::_invokevirtual:   do_invoke(str, true);           break;
1326   case Bytecodes::_invokedynamic:   do_invoke(str, false);          break;
1327 
1328   case Bytecodes::_istore:   store_local_int(str->get_index());     break;
1329   case Bytecodes::_istore_0: store_local_int(0);                    break;
1330   case Bytecodes::_istore_1: store_local_int(1);                    break;
1331   case Bytecodes::_istore_2: store_local_int(2);                    break;
1332   case Bytecodes::_istore_3: store_local_int(3);                    break;
1333 
1334   case Bytecodes::_jsr:
1335   case Bytecodes::_jsr_w: do_jsr(str);                              break;
1336 
1337   case Bytecodes::_l2d:
1338     {
1339       pop_long();
1340       push_double();
1341       break;
1342     }
1343   case Bytecodes::_l2f:
1344     {
1345       pop_long();
1346       push_float();
1347       break;
1348     }
1349   case Bytecodes::_l2i:
1350     {
1351       pop_long();
1352       push_int();
1353       break;
1354     }
1355   case Bytecodes::_ladd:
1356   case Bytecodes::_land:
1357   case Bytecodes::_ldiv:
1358   case Bytecodes::_lmul:
1359   case Bytecodes::_lor:
1360   case Bytecodes::_lrem:
1361   case Bytecodes::_lsub:
1362   case Bytecodes::_lxor:
1363     {
1364       pop_long();
1365       pop_long();
1366       push_long();
1367       break;
1368     }
1369   case Bytecodes::_laload:
1370     {
1371       pop_int();
1372       ciTypeArrayKlass* array_klass = pop_typeArray();
1373       // Put assert here for right type?
1374       push_long();
1375       break;
1376     }
1377   case Bytecodes::_lastore:
1378     {
1379       pop_long();
1380       pop_int();
1381       pop_typeArray();
1382       // assert here?
1383       break;
1384     }
1385   case Bytecodes::_lcmp:
1386     {
1387       pop_long();
1388       pop_long();
1389       push_int();
1390       break;
1391     }
1392   case Bytecodes::_lconst_0:
1393   case Bytecodes::_lconst_1:
1394     {
1395       push_long();
1396       break;
1397     }
1398   case Bytecodes::_ldc:
1399   case Bytecodes::_ldc_w:
1400   case Bytecodes::_ldc2_w:
1401     {
1402       do_ldc(str);
1403       break;
1404     }
1405 
1406   case Bytecodes::_lload:   load_local_long(str->get_index());      break;
1407   case Bytecodes::_lload_0: load_local_long(0);                     break;
1408   case Bytecodes::_lload_1: load_local_long(1);                     break;
1409   case Bytecodes::_lload_2: load_local_long(2);                     break;
1410   case Bytecodes::_lload_3: load_local_long(3);                     break;
1411 
1412   case Bytecodes::_lneg:
1413     {
1414       pop_long();
1415       push_long();
1416       break;
1417     }
1418   case Bytecodes::_lreturn:
1419     {
1420       pop_long();
1421       break;
1422     }
1423   case Bytecodes::_lshl:
1424   case Bytecodes::_lshr:
1425   case Bytecodes::_lushr:
1426     {
1427       pop_int();
1428       pop_long();
1429       push_long();
1430       break;
1431     }
1432   case Bytecodes::_lstore:   store_local_long(str->get_index());    break;
1433   case Bytecodes::_lstore_0: store_local_long(0);                   break;
1434   case Bytecodes::_lstore_1: store_local_long(1);                   break;
1435   case Bytecodes::_lstore_2: store_local_long(2);                   break;
1436   case Bytecodes::_lstore_3: store_local_long(3);                   break;
1437 
1438   case Bytecodes::_multianewarray: do_multianewarray(str);          break;
1439 
1440   case Bytecodes::_new:      do_new(str);                           break;
1441 
1442   case Bytecodes::_newarray: do_newarray(str);                      break;
1443 
1444   case Bytecodes::_pop:
1445     {
1446       pop();
1447       break;
1448     }
1449   case Bytecodes::_pop2:
1450     {
1451       pop();
1452       pop();
1453       break;
1454     }
1455 
1456   case Bytecodes::_putfield:       do_putfield(str);                 break;
1457   case Bytecodes::_putstatic:      do_putstatic(str);                break;
1458 
1459   case Bytecodes::_ret: do_ret(str);                                 break;
1460 
1461   case Bytecodes::_swap:
1462     {
1463       ciType* value1 = pop_value();
1464       ciType* value2 = pop_value();
1465       push(value1);
1466       push(value2);
1467       break;
1468     }
1469   case Bytecodes::_wide:
1470   default:
1471     {
1472       // The iterator should skip this.
1473       ShouldNotReachHere();
1474       break;
1475     }
1476   }
1477 
1478   if (CITraceTypeFlow) {
1479     print_on(tty);
1480   }
1481 
1482   return (_trap_bci != -1);
1483 }
1484 
1485 #ifndef PRODUCT
1486 // ------------------------------------------------------------------
1487 // ciTypeFlow::StateVector::print_cell_on
1488 void ciTypeFlow::StateVector::print_cell_on(outputStream* st, Cell c) const {
1489   ciType* type = type_at(c);
1490   if (type == top_type()) {
1491     st->print("top");
1492   } else if (type == bottom_type()) {
1493     st->print("bottom");
1494   } else if (type == null_type()) {
1495     st->print("null");
1496   } else if (type == long2_type()) {
1497     st->print("long2");
1498   } else if (type == double2_type()) {
1499     st->print("double2");
1500   } else if (is_int(type)) {
1501     st->print("int");
1502   } else if (is_long(type)) {
1503     st->print("long");
1504   } else if (is_float(type)) {
1505     st->print("float");
1506   } else if (is_double(type)) {
1507     st->print("double");
1508   } else if (type->is_return_address()) {
1509     st->print("address(%d)", type->as_return_address()->bci());
1510   } else {
1511     if (type->is_klass()) {
1512       type->as_klass()->name()->print_symbol_on(st);
1513     } else {
1514       st->print("UNEXPECTED TYPE");
1515       type->print();
1516     }
1517   }
1518 }
1519 
1520 // ------------------------------------------------------------------
1521 // ciTypeFlow::StateVector::print_on
1522 void ciTypeFlow::StateVector::print_on(outputStream* st) const {
1523   int num_locals   = _outer->max_locals();
1524   int num_stack    = stack_size();
1525   int num_monitors = monitor_count();
1526   st->print_cr("  State : locals %d, stack %d, monitors %d", num_locals, num_stack, num_monitors);
1527   if (num_stack >= 0) {
1528     int i;
1529     for (i = 0; i < num_locals; i++) {
1530       st->print("    local %2d : ", i);
1531       print_cell_on(st, local(i));
1532       st->cr();
1533     }
1534     for (i = 0; i < num_stack; i++) {
1535       st->print("    stack %2d : ", i);
1536       print_cell_on(st, stack(i));
1537       st->cr();
1538     }
1539   }
1540 }
1541 #endif
1542 
1543 
1544 // ------------------------------------------------------------------
1545 // ciTypeFlow::SuccIter::next
1546 //
1547 void ciTypeFlow::SuccIter::next() {
1548   int succ_ct = _pred->successors()->length();
1549   int next = _index + 1;
1550   if (next < succ_ct) {
1551     _index = next;
1552     _succ = _pred->successors()->at(next);
1553     return;
1554   }
1555   for (int i = next - succ_ct; i < _pred->exceptions()->length(); i++) {
1556     // Do not compile any code for unloaded exception types.
1557     // Following compiler passes are responsible for doing this also.
1558     ciInstanceKlass* exception_klass = _pred->exc_klasses()->at(i);
1559     if (exception_klass->is_loaded()) {
1560       _index = next;
1561       _succ = _pred->exceptions()->at(i);
1562       return;
1563     }
1564     next++;
1565   }
1566   _index = -1;
1567   _succ = NULL;
1568 }
1569 
1570 // ------------------------------------------------------------------
1571 // ciTypeFlow::SuccIter::set_succ
1572 //
1573 void ciTypeFlow::SuccIter::set_succ(Block* succ) {
1574   int succ_ct = _pred->successors()->length();
1575   if (_index < succ_ct) {
1576     _pred->successors()->at_put(_index, succ);
1577   } else {
1578     int idx = _index - succ_ct;
1579     _pred->exceptions()->at_put(idx, succ);
1580   }
1581 }
1582 
1583 // ciTypeFlow::Block
1584 //
1585 // A basic block.
1586 
1587 // ------------------------------------------------------------------
1588 // ciTypeFlow::Block::Block
1589 ciTypeFlow::Block::Block(ciTypeFlow* outer,
1590                          ciBlock *ciblk,
1591                          ciTypeFlow::JsrSet* jsrs) : _predecessors(outer->arena(), 1, 0, NULL) {
1592   _ciblock = ciblk;
1593   _exceptions = NULL;
1594   _exc_klasses = NULL;
1595   _successors = NULL;
1596   _state = new (outer->arena()) StateVector(outer);
1597   JsrSet* new_jsrs =
1598     new (outer->arena()) JsrSet(outer->arena(), jsrs->size());
1599   jsrs->copy_into(new_jsrs);
1600   _jsrs = new_jsrs;
1601   _next = NULL;
1602   _on_work_list = false;
1603   _backedge_copy = false;
1604   _has_monitorenter = false;
1605   _trap_bci = -1;
1606   _trap_index = 0;
1607   df_init();
1608 
1609   if (CITraceTypeFlow) {
1610     tty->print_cr(">> Created new block");
1611     print_on(tty);
1612   }
1613 
1614   assert(this->outer() == outer, "outer link set up");
1615   assert(!outer->have_block_count(), "must not have mapped blocks yet");
1616 }
1617 
1618 // ------------------------------------------------------------------
1619 // ciTypeFlow::Block::df_init
1620 void ciTypeFlow::Block::df_init() {
1621   _pre_order = -1; assert(!has_pre_order(), "");
1622   _post_order = -1; assert(!has_post_order(), "");
1623   _loop = NULL;
1624   _irreducible_entry = false;
1625   _rpo_next = NULL;
1626 }
1627 
1628 // ------------------------------------------------------------------
1629 // ciTypeFlow::Block::successors
1630 //
1631 // Get the successors for this Block.
1632 GrowableArray<ciTypeFlow::Block*>*
1633 ciTypeFlow::Block::successors(ciBytecodeStream* str,
1634                               ciTypeFlow::StateVector* state,
1635                               ciTypeFlow::JsrSet* jsrs) {
1636   if (_successors == NULL) {
1637     if (CITraceTypeFlow) {
1638       tty->print(">> Computing successors for block ");
1639       print_value_on(tty);
1640       tty->cr();
1641     }
1642 
1643     ciTypeFlow* analyzer = outer();
1644     Arena* arena = analyzer->arena();
1645     Block* block = NULL;
1646     bool has_successor = !has_trap() &&
1647                          (control() != ciBlock::fall_through_bci || limit() < analyzer->code_size());
1648     if (!has_successor) {
1649       _successors =
1650         new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1651       // No successors
1652     } else if (control() == ciBlock::fall_through_bci) {
1653       assert(str->cur_bci() == limit(), "bad block end");
1654       // This block simply falls through to the next.
1655       _successors =
1656         new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1657 
1658       Block* block = analyzer->block_at(limit(), _jsrs);
1659       assert(_successors->length() == FALL_THROUGH, "");
1660       _successors->append(block);
1661     } else {
1662       int current_bci = str->cur_bci();
1663       int next_bci = str->next_bci();
1664       int branch_bci = -1;
1665       Block* target = NULL;
1666       assert(str->next_bci() == limit(), "bad block end");
1667       // This block is not a simple fall-though.  Interpret
1668       // the current bytecode to find our successors.
1669       switch (str->cur_bc()) {
1670       case Bytecodes::_ifeq:         case Bytecodes::_ifne:
1671       case Bytecodes::_iflt:         case Bytecodes::_ifge:
1672       case Bytecodes::_ifgt:         case Bytecodes::_ifle:
1673       case Bytecodes::_if_icmpeq:    case Bytecodes::_if_icmpne:
1674       case Bytecodes::_if_icmplt:    case Bytecodes::_if_icmpge:
1675       case Bytecodes::_if_icmpgt:    case Bytecodes::_if_icmple:
1676       case Bytecodes::_if_acmpeq:    case Bytecodes::_if_acmpne:
1677       case Bytecodes::_ifnull:       case Bytecodes::_ifnonnull:
1678         // Our successors are the branch target and the next bci.
1679         branch_bci = str->get_dest();
1680         _successors =
1681           new (arena) GrowableArray<Block*>(arena, 2, 0, NULL);
1682         assert(_successors->length() == IF_NOT_TAKEN, "");
1683         _successors->append(analyzer->block_at(next_bci, jsrs));
1684         assert(_successors->length() == IF_TAKEN, "");
1685         _successors->append(analyzer->block_at(branch_bci, jsrs));
1686         break;
1687 
1688       case Bytecodes::_goto:
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::_jsr:
1697         branch_bci = str->get_dest();
1698         _successors =
1699           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1700         assert(_successors->length() == GOTO_TARGET, "");
1701         _successors->append(analyzer->block_at(branch_bci, jsrs));
1702         break;
1703 
1704       case Bytecodes::_goto_w:
1705       case Bytecodes::_jsr_w:
1706         _successors =
1707           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1708         assert(_successors->length() == GOTO_TARGET, "");
1709         _successors->append(analyzer->block_at(str->get_far_dest(), jsrs));
1710         break;
1711 
1712       case Bytecodes::_tableswitch:  {
1713         Bytecode_tableswitch tableswitch(str);
1714 
1715         int len = tableswitch.length();
1716         _successors =
1717           new (arena) GrowableArray<Block*>(arena, len+1, 0, NULL);
1718         int bci = current_bci + tableswitch.default_offset();
1719         Block* block = analyzer->block_at(bci, jsrs);
1720         assert(_successors->length() == SWITCH_DEFAULT, "");
1721         _successors->append(block);
1722         while (--len >= 0) {
1723           int bci = current_bci + tableswitch.dest_offset_at(len);
1724           block = analyzer->block_at(bci, jsrs);
1725           assert(_successors->length() >= SWITCH_CASES, "");
1726           _successors->append_if_missing(block);
1727         }
1728         break;
1729       }
1730 
1731       case Bytecodes::_lookupswitch: {
1732         Bytecode_lookupswitch lookupswitch(str);
1733 
1734         int npairs = lookupswitch.number_of_pairs();
1735         _successors =
1736           new (arena) GrowableArray<Block*>(arena, npairs+1, 0, NULL);
1737         int bci = current_bci + lookupswitch.default_offset();
1738         Block* block = analyzer->block_at(bci, jsrs);
1739         assert(_successors->length() == SWITCH_DEFAULT, "");
1740         _successors->append(block);
1741         while(--npairs >= 0) {
1742           LookupswitchPair pair = lookupswitch.pair_at(npairs);
1743           int bci = current_bci + pair.offset();
1744           Block* block = analyzer->block_at(bci, jsrs);
1745           assert(_successors->length() >= SWITCH_CASES, "");
1746           _successors->append_if_missing(block);
1747         }
1748         break;
1749       }
1750 
1751       case Bytecodes::_athrow:     case Bytecodes::_ireturn:
1752       case Bytecodes::_lreturn:    case Bytecodes::_freturn:
1753       case Bytecodes::_dreturn:    case Bytecodes::_areturn:
1754       case Bytecodes::_return:
1755         _successors =
1756           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1757         // No successors
1758         break;
1759 
1760       case Bytecodes::_ret: {
1761         _successors =
1762           new (arena) GrowableArray<Block*>(arena, 1, 0, NULL);
1763 
1764         Cell local = state->local(str->get_index());
1765         ciType* return_address = state->type_at(local);
1766         assert(return_address->is_return_address(), "verify: wrong type");
1767         int bci = return_address->as_return_address()->bci();
1768         assert(_successors->length() == GOTO_TARGET, "");
1769         _successors->append(analyzer->block_at(bci, jsrs));
1770         break;
1771       }
1772 
1773       case Bytecodes::_wide:
1774       default:
1775         ShouldNotReachHere();
1776         break;
1777       }
1778     }
1779 
1780     // Set predecessor information
1781     for (int i = 0; i < _successors->length(); i++) {
1782       Block* block = _successors->at(i);
1783       block->predecessors()->append(this);
1784     }
1785   }
1786   return _successors;
1787 }
1788 
1789 // ------------------------------------------------------------------
1790 // ciTypeFlow::Block:compute_exceptions
1791 //
1792 // Compute the exceptional successors and types for this Block.
1793 void ciTypeFlow::Block::compute_exceptions() {
1794   assert(_exceptions == NULL && _exc_klasses == NULL, "repeat");
1795 
1796   if (CITraceTypeFlow) {
1797     tty->print(">> Computing exceptions for block ");
1798     print_value_on(tty);
1799     tty->cr();
1800   }
1801 
1802   ciTypeFlow* analyzer = outer();
1803   Arena* arena = analyzer->arena();
1804 
1805   // Any bci in the block will do.
1806   ciExceptionHandlerStream str(analyzer->method(), start());
1807 
1808   // Allocate our growable arrays.
1809   int exc_count = str.count();
1810   _exceptions = new (arena) GrowableArray<Block*>(arena, exc_count, 0, NULL);
1811   _exc_klasses = new (arena) GrowableArray<ciInstanceKlass*>(arena, exc_count,
1812                                                              0, NULL);
1813 
1814   for ( ; !str.is_done(); str.next()) {
1815     ciExceptionHandler* handler = str.handler();
1816     int bci = handler->handler_bci();
1817     ciInstanceKlass* klass = NULL;
1818     if (bci == -1) {
1819       // There is no catch all.  It is possible to exit the method.
1820       break;
1821     }
1822     if (handler->is_catch_all()) {
1823       klass = analyzer->env()->Throwable_klass();
1824     } else {
1825       klass = handler->catch_klass();
1826     }
1827     Block* block = analyzer->block_at(bci, _jsrs);
1828     _exceptions->append(block);
1829     block->predecessors()->append(this);
1830     _exc_klasses->append(klass);
1831   }
1832 }
1833 
1834 // ------------------------------------------------------------------
1835 // ciTypeFlow::Block::set_backedge_copy
1836 // Use this only to make a pre-existing public block into a backedge copy.
1837 void ciTypeFlow::Block::set_backedge_copy(bool z) {
1838   assert(z || (z == is_backedge_copy()), "cannot make a backedge copy public");
1839   _backedge_copy = z;
1840 }
1841 
1842 // ------------------------------------------------------------------
1843 // ciTypeFlow::Block::is_clonable_exit
1844 //
1845 // At most 2 normal successors, one of which continues looping,
1846 // and all exceptional successors must exit.
1847 bool ciTypeFlow::Block::is_clonable_exit(ciTypeFlow::Loop* lp) {
1848   int normal_cnt  = 0;
1849   int in_loop_cnt = 0;
1850   for (SuccIter iter(this); !iter.done(); iter.next()) {
1851     Block* succ = iter.succ();
1852     if (iter.is_normal_ctrl()) {
1853       if (++normal_cnt > 2) return false;
1854       if (lp->contains(succ->loop())) {
1855         if (++in_loop_cnt > 1) return false;
1856       }
1857     } else {
1858       if (lp->contains(succ->loop())) return false;
1859     }
1860   }
1861   return in_loop_cnt == 1;
1862 }
1863 
1864 // ------------------------------------------------------------------
1865 // ciTypeFlow::Block::looping_succ
1866 //
1867 ciTypeFlow::Block* ciTypeFlow::Block::looping_succ(ciTypeFlow::Loop* lp) {
1868   assert(successors()->length() <= 2, "at most 2 normal successors");
1869   for (SuccIter iter(this); !iter.done(); iter.next()) {
1870     Block* succ = iter.succ();
1871     if (lp->contains(succ->loop())) {
1872       return succ;
1873     }
1874   }
1875   return NULL;
1876 }
1877 
1878 #ifndef PRODUCT
1879 // ------------------------------------------------------------------
1880 // ciTypeFlow::Block::print_value_on
1881 void ciTypeFlow::Block::print_value_on(outputStream* st) const {
1882   if (has_pre_order()) st->print("#%-2d ", pre_order());
1883   if (has_rpo())       st->print("rpo#%-2d ", rpo());
1884   st->print("[%d - %d)", start(), limit());
1885   if (is_loop_head()) st->print(" lphd");
1886   if (is_irreducible_entry()) st->print(" irred");
1887   if (_jsrs->size() > 0) { st->print("/");  _jsrs->print_on(st); }
1888   if (is_backedge_copy())  st->print("/backedge_copy");
1889 }
1890 
1891 // ------------------------------------------------------------------
1892 // ciTypeFlow::Block::print_on
1893 void ciTypeFlow::Block::print_on(outputStream* st) const {
1894   if ((Verbose || WizardMode) && (limit() >= 0)) {
1895     // Don't print 'dummy' blocks (i.e. blocks with limit() '-1')
1896     outer()->method()->print_codes_on(start(), limit(), st);
1897   }
1898   st->print_cr("  ====================================================  ");
1899   st->print ("  ");
1900   print_value_on(st);
1901   st->print(" Stored locals: "); def_locals()->print_on(st, outer()->method()->max_locals()); tty->cr();
1902   if (loop() && loop()->parent() != NULL) {
1903     st->print(" loops:");
1904     Loop* lp = loop();
1905     do {
1906       st->print(" %d<-%d", lp->head()->pre_order(),lp->tail()->pre_order());
1907       if (lp->is_irreducible()) st->print("(ir)");
1908       lp = lp->parent();
1909     } while (lp->parent() != NULL);
1910   }
1911   st->cr();
1912   _state->print_on(st);
1913   if (_successors == NULL) {
1914     st->print_cr("  No successor information");
1915   } else {
1916     int num_successors = _successors->length();
1917     st->print_cr("  Successors : %d", num_successors);
1918     for (int i = 0; i < num_successors; i++) {
1919       Block* successor = _successors->at(i);
1920       st->print("    ");
1921       successor->print_value_on(st);
1922       st->cr();
1923     }
1924   }
1925   if (_predecessors.is_empty()) {
1926     st->print_cr("  No predecessor information");
1927   } else {
1928     int num_predecessors = _predecessors.length();
1929     st->print_cr("  Predecessors : %d", num_predecessors);
1930     for (int i = 0; i < num_predecessors; i++) {
1931       Block* predecessor = _predecessors.at(i);
1932       st->print("    ");
1933       predecessor->print_value_on(st);
1934       st->cr();
1935     }
1936   }
1937   if (_exceptions == NULL) {
1938     st->print_cr("  No exception information");
1939   } else {
1940     int num_exceptions = _exceptions->length();
1941     st->print_cr("  Exceptions : %d", num_exceptions);
1942     for (int i = 0; i < num_exceptions; i++) {
1943       Block* exc_succ = _exceptions->at(i);
1944       ciInstanceKlass* exc_klass = _exc_klasses->at(i);
1945       st->print("    ");
1946       exc_succ->print_value_on(st);
1947       st->print(" -- ");
1948       exc_klass->name()->print_symbol_on(st);
1949       st->cr();
1950     }
1951   }
1952   if (has_trap()) {
1953     st->print_cr("  Traps on %d with trap index %d", trap_bci(), trap_index());
1954   }
1955   st->print_cr("  ====================================================  ");
1956 }
1957 #endif
1958 
1959 #ifndef PRODUCT
1960 // ------------------------------------------------------------------
1961 // ciTypeFlow::LocalSet::print_on
1962 void ciTypeFlow::LocalSet::print_on(outputStream* st, int limit) const {
1963   st->print("{");
1964   for (int i = 0; i < max; i++) {
1965     if (test(i)) st->print(" %d", i);
1966   }
1967   if (limit > max) {
1968     st->print(" %d..%d ", max, limit);
1969   }
1970   st->print(" }");
1971 }
1972 #endif
1973 
1974 // ciTypeFlow
1975 //
1976 // This is a pass over the bytecodes which computes the following:
1977 //   basic block structure
1978 //   interpreter type-states (a la the verifier)
1979 
1980 // ------------------------------------------------------------------
1981 // ciTypeFlow::ciTypeFlow
1982 ciTypeFlow::ciTypeFlow(ciEnv* env, ciMethod* method, int osr_bci) {
1983   _env = env;
1984   _method = method;
1985   _has_irreducible_entry = false;
1986   _osr_bci = osr_bci;
1987   _failure_reason = NULL;
1988   assert(0 <= start_bci() && start_bci() < code_size() , "correct osr_bci argument: 0 <= %d < %d", start_bci(), code_size());
1989   _work_list = NULL;
1990 
1991   int ciblock_count = _method->get_method_blocks()->num_blocks();
1992   _idx_to_blocklist = NEW_ARENA_ARRAY(arena(), GrowableArray<Block*>*, ciblock_count);
1993   for (int i = 0; i < ciblock_count; i++) {
1994     _idx_to_blocklist[i] = NULL;
1995   }
1996   _block_map = NULL;  // until all blocks are seen
1997   _jsr_records = NULL;
1998 }
1999 
2000 // ------------------------------------------------------------------
2001 // ciTypeFlow::work_list_next
2002 //
2003 // Get the next basic block from our work list.
2004 ciTypeFlow::Block* ciTypeFlow::work_list_next() {
2005   assert(!work_list_empty(), "work list must not be empty");
2006   Block* next_block = _work_list;
2007   _work_list = next_block->next();
2008   next_block->set_next(NULL);
2009   next_block->set_on_work_list(false);
2010   return next_block;
2011 }
2012 
2013 // ------------------------------------------------------------------
2014 // ciTypeFlow::add_to_work_list
2015 //
2016 // Add a basic block to our work list.
2017 // List is sorted by decreasing postorder sort (same as increasing RPO)
2018 void ciTypeFlow::add_to_work_list(ciTypeFlow::Block* block) {
2019   assert(!block->is_on_work_list(), "must not already be on work list");
2020 
2021   if (CITraceTypeFlow) {
2022     tty->print(">> Adding block ");
2023     block->print_value_on(tty);
2024     tty->print_cr(" to the work list : ");
2025   }
2026 
2027   block->set_on_work_list(true);
2028 
2029   // decreasing post order sort
2030 
2031   Block* prev = NULL;
2032   Block* current = _work_list;
2033   int po = block->post_order();
2034   while (current != NULL) {
2035     if (!current->has_post_order() || po > current->post_order())
2036       break;
2037     prev = current;
2038     current = current->next();
2039   }
2040   if (prev == NULL) {
2041     block->set_next(_work_list);
2042     _work_list = block;
2043   } else {
2044     block->set_next(current);
2045     prev->set_next(block);
2046   }
2047 
2048   if (CITraceTypeFlow) {
2049     tty->cr();
2050   }
2051 }
2052 
2053 // ------------------------------------------------------------------
2054 // ciTypeFlow::block_at
2055 //
2056 // Return the block beginning at bci which has a JsrSet compatible
2057 // with jsrs.
2058 ciTypeFlow::Block* ciTypeFlow::block_at(int bci, ciTypeFlow::JsrSet* jsrs, CreateOption option) {
2059   // First find the right ciBlock.
2060   if (CITraceTypeFlow) {
2061     tty->print(">> Requesting block for %d/", bci);
2062     jsrs->print_on(tty);
2063     tty->cr();
2064   }
2065 
2066   ciBlock* ciblk = _method->get_method_blocks()->block_containing(bci);
2067   assert(ciblk->start_bci() == bci, "bad ciBlock boundaries");
2068   Block* block = get_block_for(ciblk->index(), jsrs, option);
2069 
2070   assert(block == NULL? (option == no_create): block->is_backedge_copy() == (option == create_backedge_copy), "create option consistent with result");
2071 
2072   if (CITraceTypeFlow) {
2073     if (block != NULL) {
2074       tty->print(">> Found block ");
2075       block->print_value_on(tty);
2076       tty->cr();
2077     } else {
2078       tty->print_cr(">> No such block.");
2079     }
2080   }
2081 
2082   return block;
2083 }
2084 
2085 // ------------------------------------------------------------------
2086 // ciTypeFlow::make_jsr_record
2087 //
2088 // Make a JsrRecord for a given (entry, return) pair, if such a record
2089 // does not already exist.
2090 ciTypeFlow::JsrRecord* ciTypeFlow::make_jsr_record(int entry_address,
2091                                                    int return_address) {
2092   if (_jsr_records == NULL) {
2093     _jsr_records = new (arena()) GrowableArray<JsrRecord*>(arena(),
2094                                                            2,
2095                                                            0,
2096                                                            NULL);
2097   }
2098   JsrRecord* record = NULL;
2099   int len = _jsr_records->length();
2100   for (int i = 0; i < len; i++) {
2101     JsrRecord* record = _jsr_records->at(i);
2102     if (record->entry_address() == entry_address &&
2103         record->return_address() == return_address) {
2104       return record;
2105     }
2106   }
2107 
2108   record = new (arena()) JsrRecord(entry_address, return_address);
2109   _jsr_records->append(record);
2110   return record;
2111 }
2112 
2113 // ------------------------------------------------------------------
2114 // ciTypeFlow::flow_exceptions
2115 //
2116 // Merge the current state into all exceptional successors at the
2117 // current point in the code.
2118 void ciTypeFlow::flow_exceptions(GrowableArray<ciTypeFlow::Block*>* exceptions,
2119                                  GrowableArray<ciInstanceKlass*>* exc_klasses,
2120                                  ciTypeFlow::StateVector* state) {
2121   int len = exceptions->length();
2122   assert(exc_klasses->length() == len, "must have same length");
2123   for (int i = 0; i < len; i++) {
2124     Block* block = exceptions->at(i);
2125     ciInstanceKlass* exception_klass = exc_klasses->at(i);
2126 
2127     if (!exception_klass->is_loaded()) {
2128       // Do not compile any code for unloaded exception types.
2129       // Following compiler passes are responsible for doing this also.
2130       continue;
2131     }
2132 
2133     if (block->meet_exception(exception_klass, state)) {
2134       // Block was modified and has PO.  Add it to the work list.
2135       if (block->has_post_order() &&
2136           !block->is_on_work_list()) {
2137         add_to_work_list(block);
2138       }
2139     }
2140   }
2141 }
2142 
2143 // ------------------------------------------------------------------
2144 // ciTypeFlow::flow_successors
2145 //
2146 // Merge the current state into all successors at the current point
2147 // in the code.
2148 void ciTypeFlow::flow_successors(GrowableArray<ciTypeFlow::Block*>* successors,
2149                                  ciTypeFlow::StateVector* state) {
2150   int len = successors->length();
2151   for (int i = 0; i < len; i++) {
2152     Block* block = successors->at(i);
2153     if (block->meet(state)) {
2154       // Block was modified and has PO.  Add it to the work list.
2155       if (block->has_post_order() &&
2156           !block->is_on_work_list()) {
2157         add_to_work_list(block);
2158       }
2159     }
2160   }
2161 }
2162 
2163 // ------------------------------------------------------------------
2164 // ciTypeFlow::can_trap
2165 //
2166 // Tells if a given instruction is able to generate an exception edge.
2167 bool ciTypeFlow::can_trap(ciBytecodeStream& str) {
2168   // Cf. GenerateOopMap::do_exception_edge.
2169   if (!Bytecodes::can_trap(str.cur_bc()))  return false;
2170 
2171   switch (str.cur_bc()) {
2172     // %%% FIXME: ldc of Class can generate an exception
2173     case Bytecodes::_ldc:
2174     case Bytecodes::_ldc_w:
2175     case Bytecodes::_ldc2_w:
2176       return str.is_unresolved_klass_in_error();
2177 
2178     case Bytecodes::_aload_0:
2179       // These bytecodes can trap for rewriting.  We need to assume that
2180       // they do not throw exceptions to make the monitor analysis work.
2181       return false;
2182 
2183     case Bytecodes::_ireturn:
2184     case Bytecodes::_lreturn:
2185     case Bytecodes::_freturn:
2186     case Bytecodes::_dreturn:
2187     case Bytecodes::_areturn:
2188     case Bytecodes::_return:
2189       // We can assume the monitor stack is empty in this analysis.
2190       return false;
2191 
2192     case Bytecodes::_monitorexit:
2193       // We can assume monitors are matched in this analysis.
2194       return false;
2195 
2196     default:
2197       return true;
2198   }
2199 }
2200 
2201 // ------------------------------------------------------------------
2202 // ciTypeFlow::clone_loop_heads
2203 //
2204 // Clone the loop heads
2205 bool ciTypeFlow::clone_loop_heads(Loop* lp, StateVector* temp_vector, JsrSet* temp_set) {
2206   bool rslt = false;
2207   for (PreorderLoops iter(loop_tree_root()); !iter.done(); iter.next()) {
2208     lp = iter.current();
2209     Block* head = lp->head();
2210     if (lp == loop_tree_root() ||
2211         lp->is_irreducible() ||
2212         !head->is_clonable_exit(lp))
2213       continue;
2214 
2215     // Avoid BoxLock merge.
2216     if (EliminateNestedLocks && head->has_monitorenter())
2217       continue;
2218 
2219     // check not already cloned
2220     if (head->backedge_copy_count() != 0)
2221       continue;
2222 
2223     // Don't clone head of OSR loop to get correct types in start block.
2224     if (is_osr_flow() && head->start() == start_bci())
2225       continue;
2226 
2227     // check _no_ shared head below us
2228     Loop* ch;
2229     for (ch = lp->child(); ch != NULL && ch->head() != head; ch = ch->sibling());
2230     if (ch != NULL)
2231       continue;
2232 
2233     // Clone head
2234     Block* new_head = head->looping_succ(lp);
2235     Block* clone = clone_loop_head(lp, temp_vector, temp_set);
2236     // Update lp's info
2237     clone->set_loop(lp);
2238     lp->set_head(new_head);
2239     lp->set_tail(clone);
2240     // And move original head into outer loop
2241     head->set_loop(lp->parent());
2242 
2243     rslt = true;
2244   }
2245   return rslt;
2246 }
2247 
2248 // ------------------------------------------------------------------
2249 // ciTypeFlow::clone_loop_head
2250 //
2251 // Clone lp's head and replace tail's successors with clone.
2252 //
2253 //  |
2254 //  v
2255 // head <-> body
2256 //  |
2257 //  v
2258 // exit
2259 //
2260 // new_head
2261 //
2262 //  |
2263 //  v
2264 // head ----------\
2265 //  |             |
2266 //  |             v
2267 //  |  clone <-> body
2268 //  |    |
2269 //  | /--/
2270 //  | |
2271 //  v v
2272 // exit
2273 //
2274 ciTypeFlow::Block* ciTypeFlow::clone_loop_head(Loop* lp, StateVector* temp_vector, JsrSet* temp_set) {
2275   Block* head = lp->head();
2276   Block* tail = lp->tail();
2277   if (CITraceTypeFlow) {
2278     tty->print(">> Requesting clone of loop head "); head->print_value_on(tty);
2279     tty->print("  for predecessor ");                tail->print_value_on(tty);
2280     tty->cr();
2281   }
2282   Block* clone = block_at(head->start(), head->jsrs(), create_backedge_copy);
2283   assert(clone->backedge_copy_count() == 1, "one backedge copy for all back edges");
2284 
2285   assert(!clone->has_pre_order(), "just created");
2286   clone->set_next_pre_order();
2287 
2288   // Insert clone after (orig) tail in reverse post order
2289   clone->set_rpo_next(tail->rpo_next());
2290   tail->set_rpo_next(clone);
2291 
2292   // tail->head becomes tail->clone
2293   for (SuccIter iter(tail); !iter.done(); iter.next()) {
2294     if (iter.succ() == head) {
2295       iter.set_succ(clone);
2296       // Update predecessor information
2297       head->predecessors()->remove(tail);
2298       clone->predecessors()->append(tail);
2299     }
2300   }
2301   flow_block(tail, temp_vector, temp_set);
2302   if (head == tail) {
2303     // For self-loops, clone->head becomes clone->clone
2304     flow_block(clone, temp_vector, temp_set);
2305     for (SuccIter iter(clone); !iter.done(); iter.next()) {
2306       if (iter.succ() == head) {
2307         iter.set_succ(clone);
2308         // Update predecessor information
2309         head->predecessors()->remove(clone);
2310         clone->predecessors()->append(clone);
2311         break;
2312       }
2313     }
2314   }
2315   flow_block(clone, temp_vector, temp_set);
2316 
2317   return clone;
2318 }
2319 
2320 // ------------------------------------------------------------------
2321 // ciTypeFlow::flow_block
2322 //
2323 // Interpret the effects of the bytecodes on the incoming state
2324 // vector of a basic block.  Push the changed state to succeeding
2325 // basic blocks.
2326 void ciTypeFlow::flow_block(ciTypeFlow::Block* block,
2327                             ciTypeFlow::StateVector* state,
2328                             ciTypeFlow::JsrSet* jsrs) {
2329   if (CITraceTypeFlow) {
2330     tty->print("\n>> ANALYZING BLOCK : ");
2331     tty->cr();
2332     block->print_on(tty);
2333   }
2334   assert(block->has_pre_order(), "pre-order is assigned before 1st flow");
2335 
2336   int start = block->start();
2337   int limit = block->limit();
2338   int control = block->control();
2339   if (control != ciBlock::fall_through_bci) {
2340     limit = control;
2341   }
2342 
2343   // Grab the state from the current block.
2344   block->copy_state_into(state);
2345   state->def_locals()->clear();
2346 
2347   GrowableArray<Block*>*           exceptions = block->exceptions();
2348   GrowableArray<ciInstanceKlass*>* exc_klasses = block->exc_klasses();
2349   bool has_exceptions = exceptions->length() > 0;
2350 
2351   bool exceptions_used = false;
2352 
2353   ciBytecodeStream str(method());
2354   str.reset_to_bci(start);
2355   Bytecodes::Code code;
2356   while ((code = str.next()) != ciBytecodeStream::EOBC() &&
2357          str.cur_bci() < limit) {
2358     // Check for exceptional control flow from this point.
2359     if (has_exceptions && can_trap(str)) {
2360       flow_exceptions(exceptions, exc_klasses, state);
2361       exceptions_used = true;
2362     }
2363     // Apply the effects of the current bytecode to our state.
2364     bool res = state->apply_one_bytecode(&str);
2365 
2366     // Watch for bailouts.
2367     if (failing())  return;
2368 
2369     if (str.cur_bc() == Bytecodes::_monitorenter) {
2370       block->set_has_monitorenter();
2371     }
2372 
2373     if (res) {
2374 
2375       // We have encountered a trap.  Record it in this block.
2376       block->set_trap(state->trap_bci(), state->trap_index());
2377 
2378       if (CITraceTypeFlow) {
2379         tty->print_cr(">> Found trap");
2380         block->print_on(tty);
2381       }
2382 
2383       // Save set of locals defined in this block
2384       block->def_locals()->add(state->def_locals());
2385 
2386       // Record (no) successors.
2387       block->successors(&str, state, jsrs);
2388 
2389       assert(!has_exceptions || exceptions_used, "Not removing exceptions");
2390 
2391       // Discontinue interpretation of this Block.
2392       return;
2393     }
2394   }
2395 
2396   GrowableArray<Block*>* successors = NULL;
2397   if (control != ciBlock::fall_through_bci) {
2398     // Check for exceptional control flow from this point.
2399     if (has_exceptions && can_trap(str)) {
2400       flow_exceptions(exceptions, exc_klasses, state);
2401       exceptions_used = true;
2402     }
2403 
2404     // Fix the JsrSet to reflect effect of the bytecode.
2405     block->copy_jsrs_into(jsrs);
2406     jsrs->apply_control(this, &str, state);
2407 
2408     // Find successor edges based on old state and new JsrSet.
2409     successors = block->successors(&str, state, jsrs);
2410 
2411     // Apply the control changes to the state.
2412     state->apply_one_bytecode(&str);
2413   } else {
2414     // Fall through control
2415     successors = block->successors(&str, NULL, NULL);
2416   }
2417 
2418   // Save set of locals defined in this block
2419   block->def_locals()->add(state->def_locals());
2420 
2421   // Remove untaken exception paths
2422   if (!exceptions_used)
2423     exceptions->clear();
2424 
2425   // Pass our state to successors.
2426   flow_successors(successors, state);
2427 }
2428 
2429 // ------------------------------------------------------------------
2430 // ciTypeFlow::PreOrderLoops::next
2431 //
2432 // Advance to next loop tree using a preorder, left-to-right traversal.
2433 void ciTypeFlow::PreorderLoops::next() {
2434   assert(!done(), "must not be done.");
2435   if (_current->child() != NULL) {
2436     _current = _current->child();
2437   } else if (_current->sibling() != NULL) {
2438     _current = _current->sibling();
2439   } else {
2440     while (_current != _root && _current->sibling() == NULL) {
2441       _current = _current->parent();
2442     }
2443     if (_current == _root) {
2444       _current = NULL;
2445       assert(done(), "must be done.");
2446     } else {
2447       assert(_current->sibling() != NULL, "must be more to do");
2448       _current = _current->sibling();
2449     }
2450   }
2451 }
2452 
2453 // ------------------------------------------------------------------
2454 // ciTypeFlow::Loop::sorted_merge
2455 //
2456 // Merge the branch lp into this branch, sorting on the loop head
2457 // pre_orders. Returns the leaf of the merged branch.
2458 // Child and sibling pointers will be setup later.
2459 // Sort is (looking from leaf towards the root)
2460 //  descending on primary key: loop head's pre_order, and
2461 //  ascending  on secondary key: loop tail's pre_order.
2462 ciTypeFlow::Loop* ciTypeFlow::Loop::sorted_merge(Loop* lp) {
2463   Loop* leaf = this;
2464   Loop* prev = NULL;
2465   Loop* current = leaf;
2466   while (lp != NULL) {
2467     int lp_pre_order = lp->head()->pre_order();
2468     // Find insertion point for "lp"
2469     while (current != NULL) {
2470       if (current == lp)
2471         return leaf; // Already in list
2472       if (current->head()->pre_order() < lp_pre_order)
2473         break;
2474       if (current->head()->pre_order() == lp_pre_order &&
2475           current->tail()->pre_order() > lp->tail()->pre_order()) {
2476         break;
2477       }
2478       prev = current;
2479       current = current->parent();
2480     }
2481     Loop* next_lp = lp->parent(); // Save future list of items to insert
2482     // Insert lp before current
2483     lp->set_parent(current);
2484     if (prev != NULL) {
2485       prev->set_parent(lp);
2486     } else {
2487       leaf = lp;
2488     }
2489     prev = lp;     // Inserted item is new prev[ious]
2490     lp = next_lp;  // Next item to insert
2491   }
2492   return leaf;
2493 }
2494 
2495 // ------------------------------------------------------------------
2496 // ciTypeFlow::build_loop_tree
2497 //
2498 // Incrementally build loop tree.
2499 void ciTypeFlow::build_loop_tree(Block* blk) {
2500   assert(!blk->is_post_visited(), "precondition");
2501   Loop* innermost = NULL; // merge of loop tree branches over all successors
2502 
2503   for (SuccIter iter(blk); !iter.done(); iter.next()) {
2504     Loop*  lp   = NULL;
2505     Block* succ = iter.succ();
2506     if (!succ->is_post_visited()) {
2507       // Found backedge since predecessor post visited, but successor is not
2508       assert(succ->pre_order() <= blk->pre_order(), "should be backedge");
2509 
2510       // Create a LoopNode to mark this loop.
2511       lp = new (arena()) Loop(succ, blk);
2512       if (succ->loop() == NULL)
2513         succ->set_loop(lp);
2514       // succ->loop will be updated to innermost loop on a later call, when blk==succ
2515 
2516     } else {  // Nested loop
2517       lp = succ->loop();
2518 
2519       // If succ is loop head, find outer loop.
2520       while (lp != NULL && lp->head() == succ) {
2521         lp = lp->parent();
2522       }
2523       if (lp == NULL) {
2524         // Infinite loop, it's parent is the root
2525         lp = loop_tree_root();
2526       }
2527     }
2528 
2529     // Check for irreducible loop.
2530     // Successor has already been visited. If the successor's loop head
2531     // has already been post-visited, then this is another entry into the loop.
2532     while (lp->head()->is_post_visited() && lp != loop_tree_root()) {
2533       _has_irreducible_entry = true;
2534       lp->set_irreducible(succ);
2535       if (!succ->is_on_work_list()) {
2536         // Assume irreducible entries need more data flow
2537         add_to_work_list(succ);
2538       }
2539       Loop* plp = lp->parent();
2540       if (plp == NULL) {
2541         // This only happens for some irreducible cases.  The parent
2542         // will be updated during a later pass.
2543         break;
2544       }
2545       lp = plp;
2546     }
2547 
2548     // Merge loop tree branch for all successors.
2549     innermost = innermost == NULL ? lp : innermost->sorted_merge(lp);
2550 
2551   } // end loop
2552 
2553   if (innermost == NULL) {
2554     assert(blk->successors()->length() == 0, "CFG exit");
2555     blk->set_loop(loop_tree_root());
2556   } else if (innermost->head() == blk) {
2557     // If loop header, complete the tree pointers
2558     if (blk->loop() != innermost) {
2559 #ifdef ASSERT
2560       assert(blk->loop()->head() == innermost->head(), "same head");
2561       Loop* dl;
2562       for (dl = innermost; dl != NULL && dl != blk->loop(); dl = dl->parent());
2563       assert(dl == blk->loop(), "blk->loop() already in innermost list");
2564 #endif
2565       blk->set_loop(innermost);
2566     }
2567     innermost->def_locals()->add(blk->def_locals());
2568     Loop* l = innermost;
2569     Loop* p = l->parent();
2570     while (p && l->head() == blk) {
2571       l->set_sibling(p->child());  // Put self on parents 'next child'
2572       p->set_child(l);             // Make self the first child of parent
2573       p->def_locals()->add(l->def_locals());
2574       l = p;                       // Walk up the parent chain
2575       p = l->parent();
2576     }
2577   } else {
2578     blk->set_loop(innermost);
2579     innermost->def_locals()->add(blk->def_locals());
2580   }
2581 }
2582 
2583 // ------------------------------------------------------------------
2584 // ciTypeFlow::Loop::contains
2585 //
2586 // Returns true if lp is nested loop.
2587 bool ciTypeFlow::Loop::contains(ciTypeFlow::Loop* lp) const {
2588   assert(lp != NULL, "");
2589   if (this == lp || head() == lp->head()) return true;
2590   int depth1 = depth();
2591   int depth2 = lp->depth();
2592   if (depth1 > depth2)
2593     return false;
2594   while (depth1 < depth2) {
2595     depth2--;
2596     lp = lp->parent();
2597   }
2598   return this == lp;
2599 }
2600 
2601 // ------------------------------------------------------------------
2602 // ciTypeFlow::Loop::depth
2603 //
2604 // Loop depth
2605 int ciTypeFlow::Loop::depth() const {
2606   int dp = 0;
2607   for (Loop* lp = this->parent(); lp != NULL; lp = lp->parent())
2608     dp++;
2609   return dp;
2610 }
2611 
2612 #ifndef PRODUCT
2613 // ------------------------------------------------------------------
2614 // ciTypeFlow::Loop::print
2615 void ciTypeFlow::Loop::print(outputStream* st, int indent) const {
2616   for (int i = 0; i < indent; i++) st->print(" ");
2617   st->print("%d<-%d %s",
2618             is_root() ? 0 : this->head()->pre_order(),
2619             is_root() ? 0 : this->tail()->pre_order(),
2620             is_irreducible()?" irr":"");
2621   st->print(" defs: ");
2622   def_locals()->print_on(st, _head->outer()->method()->max_locals());
2623   st->cr();
2624   for (Loop* ch = child(); ch != NULL; ch = ch->sibling())
2625     ch->print(st, indent+2);
2626 }
2627 #endif
2628 
2629 // ------------------------------------------------------------------
2630 // ciTypeFlow::df_flow_types
2631 //
2632 // Perform the depth first type flow analysis. Helper for flow_types.
2633 void ciTypeFlow::df_flow_types(Block* start,
2634                                bool do_flow,
2635                                StateVector* temp_vector,
2636                                JsrSet* temp_set) {
2637   int dft_len = 100;
2638   GrowableArray<Block*> stk(dft_len);
2639 
2640   ciBlock* dummy = _method->get_method_blocks()->make_dummy_block();
2641   JsrSet* root_set = new JsrSet(0);
2642   Block* root_head = new (arena()) Block(this, dummy, root_set);
2643   Block* root_tail = new (arena()) Block(this, dummy, root_set);
2644   root_head->set_pre_order(0);
2645   root_head->set_post_order(0);
2646   root_tail->set_pre_order(max_jint);
2647   root_tail->set_post_order(max_jint);
2648   set_loop_tree_root(new (arena()) Loop(root_head, root_tail));
2649 
2650   stk.push(start);
2651 
2652   _next_pre_order = 0;  // initialize pre_order counter
2653   _rpo_list = NULL;
2654   int next_po = 0;      // initialize post_order counter
2655 
2656   // Compute RPO and the control flow graph
2657   int size;
2658   while ((size = stk.length()) > 0) {
2659     Block* blk = stk.top(); // Leave node on stack
2660     if (!blk->is_visited()) {
2661       // forward arc in graph
2662       assert (!blk->has_pre_order(), "");
2663       blk->set_next_pre_order();
2664 
2665       if (_next_pre_order >= (int)Compile::current()->max_node_limit() / 2) {
2666         // Too many basic blocks.  Bail out.
2667         // This can happen when try/finally constructs are nested to depth N,
2668         // and there is O(2**N) cloning of jsr bodies.  See bug 4697245!
2669         // "MaxNodeLimit / 2" is used because probably the parser will
2670         // generate at least twice that many nodes and bail out.
2671         record_failure("too many basic blocks");
2672         return;
2673       }
2674       if (do_flow) {
2675         flow_block(blk, temp_vector, temp_set);
2676         if (failing()) return; // Watch for bailouts.
2677       }
2678     } else if (!blk->is_post_visited()) {
2679       // cross or back arc
2680       for (SuccIter iter(blk); !iter.done(); iter.next()) {
2681         Block* succ = iter.succ();
2682         if (!succ->is_visited()) {
2683           stk.push(succ);
2684         }
2685       }
2686       if (stk.length() == size) {
2687         // There were no additional children, post visit node now
2688         stk.pop(); // Remove node from stack
2689 
2690         build_loop_tree(blk);
2691         blk->set_post_order(next_po++);   // Assign post order
2692         prepend_to_rpo_list(blk);
2693         assert(blk->is_post_visited(), "");
2694 
2695         if (blk->is_loop_head() && !blk->is_on_work_list()) {
2696           // Assume loop heads need more data flow
2697           add_to_work_list(blk);
2698         }
2699       }
2700     } else {
2701       stk.pop(); // Remove post-visited node from stack
2702     }
2703   }
2704 }
2705 
2706 // ------------------------------------------------------------------
2707 // ciTypeFlow::flow_types
2708 //
2709 // Perform the type flow analysis, creating and cloning Blocks as
2710 // necessary.
2711 void ciTypeFlow::flow_types() {
2712   ResourceMark rm;
2713   StateVector* temp_vector = new StateVector(this);
2714   JsrSet* temp_set = new JsrSet(4);
2715 
2716   // Create the method entry block.
2717   Block* start = block_at(start_bci(), temp_set);
2718 
2719   // Load the initial state into it.
2720   const StateVector* start_state = get_start_state();
2721   if (failing())  return;
2722   start->meet(start_state);
2723 
2724   // Depth first visit
2725   df_flow_types(start, true /*do flow*/, temp_vector, temp_set);
2726 
2727   if (failing())  return;
2728   assert(_rpo_list == start, "must be start");
2729 
2730   // Any loops found?
2731   if (loop_tree_root()->child() != NULL &&
2732       env()->comp_level() >= CompLevel_full_optimization) {
2733       // Loop optimizations are not performed on Tier1 compiles.
2734 
2735     bool changed = clone_loop_heads(loop_tree_root(), temp_vector, temp_set);
2736 
2737     // If some loop heads were cloned, recompute postorder and loop tree
2738     if (changed) {
2739       loop_tree_root()->set_child(NULL);
2740       for (Block* blk = _rpo_list; blk != NULL;) {
2741         Block* next = blk->rpo_next();
2742         blk->df_init();
2743         blk = next;
2744       }
2745       df_flow_types(start, false /*no flow*/, temp_vector, temp_set);
2746     }
2747   }
2748 
2749   if (CITraceTypeFlow) {
2750     tty->print_cr("\nLoop tree");
2751     loop_tree_root()->print();
2752   }
2753 
2754   // Continue flow analysis until fixed point reached
2755 
2756   debug_only(int max_block = _next_pre_order;)
2757 
2758   while (!work_list_empty()) {
2759     Block* blk = work_list_next();
2760     assert (blk->has_post_order(), "post order assigned above");
2761 
2762     flow_block(blk, temp_vector, temp_set);
2763 
2764     assert (max_block == _next_pre_order, "no new blocks");
2765     assert (!failing(), "no more bailouts");
2766   }
2767 }
2768 
2769 // ------------------------------------------------------------------
2770 // ciTypeFlow::map_blocks
2771 //
2772 // Create the block map, which indexes blocks in reverse post-order.
2773 void ciTypeFlow::map_blocks() {
2774   assert(_block_map == NULL, "single initialization");
2775   int block_ct = _next_pre_order;
2776   _block_map = NEW_ARENA_ARRAY(arena(), Block*, block_ct);
2777   assert(block_ct == block_count(), "");
2778 
2779   Block* blk = _rpo_list;
2780   for (int m = 0; m < block_ct; m++) {
2781     int rpo = blk->rpo();
2782     assert(rpo == m, "should be sequential");
2783     _block_map[rpo] = blk;
2784     blk = blk->rpo_next();
2785   }
2786   assert(blk == NULL, "should be done");
2787 
2788   for (int j = 0; j < block_ct; j++) {
2789     assert(_block_map[j] != NULL, "must not drop any blocks");
2790     Block* block = _block_map[j];
2791     // Remove dead blocks from successor lists:
2792     for (int e = 0; e <= 1; e++) {
2793       GrowableArray<Block*>* l = e? block->exceptions(): block->successors();
2794       for (int k = 0; k < l->length(); k++) {
2795         Block* s = l->at(k);
2796         if (!s->has_post_order()) {
2797           if (CITraceTypeFlow) {
2798             tty->print("Removing dead %s successor of #%d: ", (e? "exceptional":  "normal"), block->pre_order());
2799             s->print_value_on(tty);
2800             tty->cr();
2801           }
2802           l->remove(s);
2803           --k;
2804         }
2805       }
2806     }
2807   }
2808 }
2809 
2810 // ------------------------------------------------------------------
2811 // ciTypeFlow::get_block_for
2812 //
2813 // Find a block with this ciBlock which has a compatible JsrSet.
2814 // If no such block exists, create it, unless the option is no_create.
2815 // If the option is create_backedge_copy, always create a fresh backedge copy.
2816 ciTypeFlow::Block* ciTypeFlow::get_block_for(int ciBlockIndex, ciTypeFlow::JsrSet* jsrs, CreateOption option) {
2817   Arena* a = arena();
2818   GrowableArray<Block*>* blocks = _idx_to_blocklist[ciBlockIndex];
2819   if (blocks == NULL) {
2820     // Query only?
2821     if (option == no_create)  return NULL;
2822 
2823     // Allocate the growable array.
2824     blocks = new (a) GrowableArray<Block*>(a, 4, 0, NULL);
2825     _idx_to_blocklist[ciBlockIndex] = blocks;
2826   }
2827 
2828   if (option != create_backedge_copy) {
2829     int len = blocks->length();
2830     for (int i = 0; i < len; i++) {
2831       Block* block = blocks->at(i);
2832       if (!block->is_backedge_copy() && block->is_compatible_with(jsrs)) {
2833         return block;
2834       }
2835     }
2836   }
2837 
2838   // Query only?
2839   if (option == no_create)  return NULL;
2840 
2841   // We did not find a compatible block.  Create one.
2842   Block* new_block = new (a) Block(this, _method->get_method_blocks()->block(ciBlockIndex), jsrs);
2843   if (option == create_backedge_copy)  new_block->set_backedge_copy(true);
2844   blocks->append(new_block);
2845   return new_block;
2846 }
2847 
2848 // ------------------------------------------------------------------
2849 // ciTypeFlow::backedge_copy_count
2850 //
2851 int ciTypeFlow::backedge_copy_count(int ciBlockIndex, ciTypeFlow::JsrSet* jsrs) const {
2852   GrowableArray<Block*>* blocks = _idx_to_blocklist[ciBlockIndex];
2853 
2854   if (blocks == NULL) {
2855     return 0;
2856   }
2857 
2858   int count = 0;
2859   int len = blocks->length();
2860   for (int i = 0; i < len; i++) {
2861     Block* block = blocks->at(i);
2862     if (block->is_backedge_copy() && block->is_compatible_with(jsrs)) {
2863       count++;
2864     }
2865   }
2866 
2867   return count;
2868 }
2869 
2870 // ------------------------------------------------------------------
2871 // ciTypeFlow::do_flow
2872 //
2873 // Perform type inference flow analysis.
2874 void ciTypeFlow::do_flow() {
2875   if (CITraceTypeFlow) {
2876     tty->print_cr("\nPerforming flow analysis on method");
2877     method()->print();
2878     if (is_osr_flow())  tty->print(" at OSR bci %d", start_bci());
2879     tty->cr();
2880     method()->print_codes();
2881   }
2882   if (CITraceTypeFlow) {
2883     tty->print_cr("Initial CI Blocks");
2884     print_on(tty);
2885   }
2886   flow_types();
2887   // Watch for bailouts.
2888   if (failing()) {
2889     return;
2890   }
2891 
2892   map_blocks();
2893 
2894   if (CIPrintTypeFlow || CITraceTypeFlow) {
2895     rpo_print_on(tty);
2896   }
2897 }
2898 
2899 // ------------------------------------------------------------------
2900 // ciTypeFlow::is_dominated_by
2901 //
2902 // Determine if the instruction at bci is dominated by the instruction at dom_bci.
2903 bool ciTypeFlow::is_dominated_by(int bci, int dom_bci) {
2904   assert(!method()->has_jsrs(), "jsrs are not supported");
2905 
2906   ResourceMark rm;
2907   JsrSet* jsrs = new ciTypeFlow::JsrSet();
2908   int        index = _method->get_method_blocks()->block_containing(bci)->index();
2909   int    dom_index = _method->get_method_blocks()->block_containing(dom_bci)->index();
2910   Block*     block = get_block_for(index, jsrs, ciTypeFlow::no_create);
2911   Block* dom_block = get_block_for(dom_index, jsrs, ciTypeFlow::no_create);
2912 
2913   // Start block dominates all other blocks
2914   if (start_block()->rpo() == dom_block->rpo()) {
2915     return true;
2916   }
2917 
2918   // Dominated[i] is true if block i is dominated by dom_block
2919   int num_blocks = block_count();
2920   bool* dominated = NEW_RESOURCE_ARRAY(bool, num_blocks);
2921   for (int i = 0; i < num_blocks; ++i) {
2922     dominated[i] = true;
2923   }
2924   dominated[start_block()->rpo()] = false;
2925 
2926   // Iterative dominator algorithm
2927   bool changed = true;
2928   while (changed) {
2929     changed = false;
2930     // Use reverse postorder iteration
2931     for (Block* blk = _rpo_list; blk != NULL; blk = blk->rpo_next()) {
2932       if (blk->is_start()) {
2933         // Ignore start block
2934         continue;
2935       }
2936       // The block is dominated if it is the dominating block
2937       // itself or if all predecessors are dominated.
2938       int index = blk->rpo();
2939       bool dom = (index == dom_block->rpo());
2940       if (!dom) {
2941         // Check if all predecessors are dominated
2942         dom = true;
2943         for (int i = 0; i < blk->predecessors()->length(); ++i) {
2944           Block* pred = blk->predecessors()->at(i);
2945           if (!dominated[pred->rpo()]) {
2946             dom = false;
2947             break;
2948           }
2949         }
2950       }
2951       // Update dominator information
2952       if (dominated[index] != dom) {
2953         changed = true;
2954         dominated[index] = dom;
2955       }
2956     }
2957   }
2958   // block dominated by dom_block?
2959   return dominated[block->rpo()];
2960 }
2961 
2962 // ------------------------------------------------------------------
2963 // ciTypeFlow::record_failure()
2964 // The ciTypeFlow object keeps track of failure reasons separately from the ciEnv.
2965 // This is required because there is not a 1-1 relation between the ciEnv and
2966 // the TypeFlow passes within a compilation task.  For example, if the compiler
2967 // is considering inlining a method, it will request a TypeFlow.  If that fails,
2968 // the compilation as a whole may continue without the inlining.  Some TypeFlow
2969 // requests are not optional; if they fail the requestor is responsible for
2970 // copying the failure reason up to the ciEnv.  (See Parse::Parse.)
2971 void ciTypeFlow::record_failure(const char* reason) {
2972   if (env()->log() != NULL) {
2973     env()->log()->elem("failure reason='%s' phase='typeflow'", reason);
2974   }
2975   if (_failure_reason == NULL) {
2976     // Record the first failure reason.
2977     _failure_reason = reason;
2978   }
2979 }
2980 
2981 #ifndef PRODUCT
2982 // ------------------------------------------------------------------
2983 // ciTypeFlow::print_on
2984 void ciTypeFlow::print_on(outputStream* st) const {
2985   // Walk through CI blocks
2986   st->print_cr("********************************************************");
2987   st->print   ("TypeFlow for ");
2988   method()->name()->print_symbol_on(st);
2989   int limit_bci = code_size();
2990   st->print_cr("  %d bytes", limit_bci);
2991   ciMethodBlocks* mblks = _method->get_method_blocks();
2992   ciBlock* current = NULL;
2993   for (int bci = 0; bci < limit_bci; bci++) {
2994     ciBlock* blk = mblks->block_containing(bci);
2995     if (blk != NULL && blk != current) {
2996       current = blk;
2997       current->print_on(st);
2998 
2999       GrowableArray<Block*>* blocks = _idx_to_blocklist[blk->index()];
3000       int num_blocks = (blocks == NULL) ? 0 : blocks->length();
3001 
3002       if (num_blocks == 0) {
3003         st->print_cr("  No Blocks");
3004       } else {
3005         for (int i = 0; i < num_blocks; i++) {
3006           Block* block = blocks->at(i);
3007           block->print_on(st);
3008         }
3009       }
3010       st->print_cr("--------------------------------------------------------");
3011       st->cr();
3012     }
3013   }
3014   st->print_cr("********************************************************");
3015   st->cr();
3016 }
3017 
3018 void ciTypeFlow::rpo_print_on(outputStream* st) const {
3019   st->print_cr("********************************************************");
3020   st->print   ("TypeFlow for ");
3021   method()->name()->print_symbol_on(st);
3022   int limit_bci = code_size();
3023   st->print_cr("  %d bytes", limit_bci);
3024   for (Block* blk = _rpo_list; blk != NULL; blk = blk->rpo_next()) {
3025     blk->print_on(st);
3026     st->print_cr("--------------------------------------------------------");
3027     st->cr();
3028   }
3029   st->print_cr("********************************************************");
3030   st->cr();
3031 }
3032 #endif